JP2004003397A - Arrangement for controlling torque of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a stable torque control to be performed in a mode which gives priority to the stability of a torque control even when ignition timing is computed to timing which was late for calculation of a fuel oil consumption. <P>SOLUTION: In response mode which gives priority to the response of the torque control, the fuel oil consumption is computed based on the condition torque newest to the fuel oil consumption calculation timing, and the response of the torque control is raised by computing an ignition timing based on the indication torque newest to subsequent ignition timing calculation timing. On the other hand, in a stability mode which gives priority to the stability of the torque control, the fuel oil consumption is computed based on the latest indication torque under the fuel oil consumption calculation timing, and the stability of the torque control is raised by computing the ignition timing based on the former indication torque (indication torque in the fuel oil consumption calculation timing in front of for example) to subsequent ignition timing calculation timing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a torque control device for an internal combustion engine that controls a fuel injection amount (for example, whether or not fuel is cut) and an ignition timing based on a command torque of the internal combustion engine.
[0002]
[Prior art]
In recent automobiles, for example, as shown in Japanese Patent No. 3211512, when performing traction control or the like for preventing idle rotation (slip) of drive wheels, the fuel of each cylinder is set so that the output torque of the engine becomes the specified torque. In some cases, “torque control” for controlling an injection amount (for example, whether or not fuel is cut) and an ignition timing is performed.
[0003]
[Problems to be solved by the invention]
In an intake port injection type engine, which is the most common internal combustion engine today, the fuel injected from the fuel injection valve is sucked into the cylinder by the end of the intake stroke, as shown in FIG. By the end of the fuel injection (normally, the fuel injection is stopped before the exhaust stroke to prevent blow-through during the valve overlap period), the ignition plug is energized in the compression stroke and The mixture is burned (exploded) by ignition. Therefore, a delay of, for example, about 360 to 720 ° CA occurs from the start of fuel injection to the start of energization of the spark plug.
[0004]
Therefore, in order to perform torque control with good responsiveness to a change in the instruction torque, the fuel injection amount calculation timing and the ignition timing calculation timing are set immediately before the fuel injection start timing and the ignition plug energization start timing, respectively. As shown in FIG. 4A, at the fuel injection amount calculation timing, the fuel injection amount is calculated based on the latest instruction torque at that time, and then the ignition timing calculation timing (for example, after elapse of 360 to 720 ° CA) Then, it is possible to calculate the ignition timing based on the latest instruction torque at that time.
[0005]
However, in this torque control method, as shown in FIG. 4A, if the indicated torque changes, the indicated torque value used for calculating the fuel injection amount and the indicated torque value used for calculating the ignition timing differ. Therefore, if the amount of the change is large, the fluctuation of the output torque with respect to the instructed torque may increase as in the example described below, resulting in unstable torque control.
[0006]
For example, as shown by the solid line in FIG. 4A, in a certain cylinder, the command torque at the fuel injection amount calculation timing does not require the fuel cut, but at the subsequent ignition timing calculation timing, the command torque decreases. If the command torque is too low to be realized by the ignition retard, the torque obtained during the explosion stroke of this cylinder becomes larger than the command torque at the ignition timing calculation timing. Further, as indicated by a two-dot chain line in FIG. 4A, in the cylinder in which fuel is cut, the command torque at the fuel injection amount calculation timing does not require the fuel return (restart of fuel injection), but the subsequent ignition At the timing of the timing calculation, the indicated torque is increasing, and even if it is necessary to return the fuel to achieve the indicated torque, it is already too late to perform the fuel return, and the torque obtained during the cylinder's explosion stroke is ignited. It becomes smaller than the instruction torque at the timing calculation timing.
[0007]
Further, in order to reduce the torque shock at the time of fuel cut or fuel return (restart of fuel injection) of the internal combustion engine, when increasing the number of fuel cut cylinders of the internal combustion engine, the normal fuel injection order of each cylinder is reduced. Sequential cuts in which fuel injection is cut in the order of one cylinder at a time, or fuel injection in the order of one cylinder at a time compared to the normal fuel injection order of each cylinder when reducing the number of fuel cut cylinders in the internal combustion engine There is a method in which a sequential return is performed to restart the operation.
[0008]
Conventionally, when performing such a sequential cut (or sequential return), a subsequent fuel cut cylinder (or fuel return cylinder) is set by a map or the like according to the first fuel cut cylinder (or fuel return cylinder), Alternatively, there is an engine in which the next fuel cut cylinder (or fuel return cylinder) is determined by integrating crank angles. However, in such a control method, since the fuel cut cylinder (or the fuel return cylinder) is not controlled in accordance with the command torque, it is necessary to perform the sequential cut (or sequential return) accurately reflecting the command torque. Can not.
[0009]
The present invention has been made in consideration of these circumstances, and a first object is to perform stable torque control even when the ignition timing is calculated at a timing delayed from the calculation of the fuel injection amount. The second object is to enable a sequential cut or a sequential return that accurately reflects the indicated torque.
[0010]
[Means for Solving the Problems]
In order to achieve the first object, a torque control device for an internal combustion engine according to claim 1 of the present invention calculates a command torque by a command torque calculation means at each predetermined command torque calculation timing, and performs a predetermined fuel injection. The fuel injection amount is calculated by the fuel injection amount calculating means based on the instruction torque at each amount calculation timing, and the ignition timing is ignited based on the instruction torque at each predetermined ignition timing calculation timing that is later than the fuel injection amount calculation timing. It is calculated by the timing calculating means. When calculating the ignition timing during the stability mode operation in which the stability of the torque control is prioritized, the ignition timing is calculated based on the past instruction torque calculated before the instruction torque at the ignition timing calculation timing. This is calculated.
[0011]
When calculating the ignition timing at the ignition timing calculation timing that is later than the fuel injection amount calculation timing, if the past instruction torque is used, the deviation between the instruction torque used for the fuel injection amount calculation and the instruction torque used for the ignition timing calculation is calculated. Since the output torque can be reduced, the fluctuation of the output torque with respect to the instruction torque can be reduced, and the stability of the torque control can be improved. Therefore, if the ignition timing is calculated based on the past instruction torque during the stability mode operation in which the stability of the torque control is prioritized, the ignition timing is calculated at the ignition timing calculation timing that is later than the fuel injection amount calculation timing. Is calculated, stable torque control can be realized.
[0012]
In this case, when calculating the ignition timing during the stability mode operation, the instruction torque at the immediately preceding fuel injection amount calculation timing may be used as the past instruction torque. With this configuration, the fuel injection amount and the ignition timing can be calculated based on the same instruction torque (instruction torque at the fuel injection amount calculation timing), so that more stable torque control can be realized.
[0013]
By the way, if the ignition timing is calculated based on the past command torque, the responsiveness of the torque control may be reduced. As a countermeasure, the command torque may be calculated based on the future rotation speed predicted by the future rotation speed prediction means during the stability mode operation. In this way, the command torque taking into account the behavior of the future rotational speed of the internal combustion engine can be calculated, so that even when the ignition timing is calculated based on the past command torque, the response of the torque control can be improved. Can be improved.
[0014]
In this case, the future rotational speed can be obtained by integrating the shaft torque of the internal combustion engine. However, when the integration is used, the calculation load on the control device increases.
[0015]
Therefore, the rotation speed of the internal combustion engine is detected by the rotation speed detection means, and the shaft torque is calculated by the shaft torque calculation means based on the intake air amount of the internal combustion engine. The future rotation speed may be calculated based on the calculated rotation speed and the shaft torque calculated by the shaft torque calculation means. Since the subsequent behavior of the rotation speed is determined by the behavior of the shaft torque, the future rotation speed is accurately calculated based on the latest rotation speed by using the rotation speed and the shaft torque detected by the rotation speed detection means. In addition, the integration becomes unnecessary, and the calculation load of the control device can be reduced.
[0016]
On the other hand, when calculating the ignition timing during the response mode operation giving priority to the responsiveness of the torque control, the ignition timing is calculated based on the instruction torque at the ignition timing calculation timing. good. With this configuration, in the response mode in which the responsiveness of the torque control is prioritized, when calculating the ignition timing, the ignition timing can be calculated based on the latest instruction torque, and the torque control with good responsiveness is performed. be able to.
[0017]
Here, when switching between the response mode and the stability mode, when the command torque used for calculating the ignition timing is instantaneously switched between the latest command torque and the past command torque, the change amount is large. In such a case, the command torque used for calculating the ignition timing changes abruptly, so that the output torque may change abruptly and adversely affect drivability.
[0018]
As a countermeasure, when switching between the response mode and the stability mode, the command torque used for calculating the ignition timing may be gradually changed by the command torque gradually changing means. In this way, when switching between the response mode and the stability mode, it is possible to prevent a sudden change in the instruction torque used for calculating the ignition timing, and to prevent a sudden change in the output torque, thereby preventing deterioration in drivability. can do.
[0019]
Further, when performing a sequential cut or a sequential return in which fuel injection is cut or restarted in an order skipped by a predetermined number of cylinders with respect to a normal fuel injection order of each cylinder, as in claims 7 and 8, The sequential control means changes the torque generation rate, which is the ratio of the command torque to the output torque when fuel is injected in all cylinders, by a predetermined amount at predetermined intervals, and changes the number of fuel cut cylinders according to the torque generation rate. Therefore, it is preferable to execute the sequential cut or the sequential return.
[0020]
The torque generation rate can directly correspond to the number of fuel cut cylinders. For example, in an internal combustion engine having five cylinders, when the torque generation rate is 0.8 (= 4/5), only one cylinder needs to be cut. Focusing on this point, if the torque generation rate is reduced (or increased) by a predetermined change amount in a predetermined cycle, the torque generation rate is reduced (or increased) at such a rate that sequential cut (or sequential return) is performed. If the number of fuel cut cylinders is increased (or decreased) according to the torque generation rate thus changed, sequential cut (or sequential return) can be performed. As a result, it is possible to realize a sequential cut or a sequential return that accurately reflects the instruction torque (torque generation rate).
[0021]
In this case, in the internal combustion engine in which the total number of cylinders is Y cylinders (where Y is an integer of 3 or more), n cycles (where n is an integer of 0 or more) are performed with respect to the normal fuel injection order of each cylinder. In the case where the sequential cut or the sequential return is executed in the order of skipping every X cylinders (where X is an integer of 1 or more) every other cycle, the predetermined cycle for changing the torque generation rate is set to the normal ignition interval of the internal combustion engine ( = 720 ° C. A / Y), and the predetermined change amount is preferably set to 1 / Y / (X + 1 + n × Y).
[0022]
For example, in a case where a sequential cut or a sequential return is performed in an internal combustion engine having a total number of five cylinders in a sequence of skipping one cylinder at a time every 0 cycles (every cycle) with respect to a normal fuel injection sequence of each cylinder. Substitutes Y = 5, n = 0, and X = 1 into 1 / Y / (X + 1 + n × Y), and sets the predetermined change amount to 1/5 / (1 + 1 + 0 × 5) = 0.1. In this case, the torque generation rate can be decreased or increased by 0.1 for each ignition, so that the torque generation rate is generated for every two ignitions (that is, in the order of skipping one cylinder at a time with respect to the normal fuel injection order). The rate can be decreased or increased by 0.2 (that is, a torque generation rate corresponding to fuel cut or fuel return for one cylinder of a five-cylinder internal combustion engine). Thus, in the five-cylinder internal combustion engine, the sequential cut or the sequential return can be executed in the order in which the normal fuel injection order of each cylinder is skipped one by one.
[0023]
By the way, even if the torque generation rate is changed at a fixed rate (by a predetermined change amount in a predetermined cycle) so that the sequential cut or the sequential return is performed, the fuel injection amount calculation timing (that is, the fuel cut or the fuel return in accordance with the torque generation rate). When the fuel injection amount is calculated, the change in the torque generation rate received at each fuel injection amount calculation timing may not be constant, and the fuel cut order and the fuel return order may be disturbed. Further, if the fuel injection timing is not fixed, it is difficult to determine in advance whether fuel cut or fuel return is in time, and it becomes difficult to specify a cylinder to be fuel cut or fuel returned next.
[0024]
As a countermeasure, the fuel injection amount calculation timing and the fuel injection timing may be fixed during execution of the sequential cut and / or the sequential return. If the fuel injection amount calculation timing is fixed, the change in the torque generation rate received at each fuel injection amount calculation timing can be made a constant rate. Sequential cut and sequential return can be executed in the same order. Further, if the fuel injection timing is fixed, it is possible to easily determine in advance the cylinder in which fuel cut or fuel return will be in time, and easily identify the cylinder in which fuel cut or fuel return will be performed next.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of the entire engine control system will be described with reference to FIG. For example, a five-cylinder engine 11, which is an internal combustion engine, has five cylinders of a first cylinder (# 1) to a fifth cylinder (# 5), and an air cleaner is provided at the most upstream portion of an intake pipe 12 of the engine 11. An air flow meter 14 for detecting the amount of intake air is provided downstream of the air cleaner 13. A throttle valve 15 is provided downstream of the air flow meter 14, and the opening of the throttle valve 15 (throttle opening) is detected by a throttle opening sensor 16.
[0026]
Further, a surge tank 17 is provided downstream of the throttle valve 15, and the surge tank 17 is provided with an intake pipe pressure sensor 18 for detecting an intake pipe pressure. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached near an intake port of the intake manifold 19 of each cylinder. I have.
[0027]
An ignition plug 21 is attached to a cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 21. Further, a cooling water temperature sensor 22 for detecting a cooling water temperature and a crank angle sensor 23 (rotation speed detection means) for detecting an engine rotation speed are attached to a cylinder block of the engine 11.
[0028]
On the other hand, a catalyst 25 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas is provided in an exhaust pipe 24 of the engine 11, and an air-fuel ratio or a lean An exhaust gas sensor 26 (an air-fuel ratio sensor, an oxygen sensor, etc.) for detecting the air / rich ratio is provided.
[0029]
The outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 27. The ECU 27 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), thereby controlling the fuel injection amount of the fuel injection valve 20 according to the engine operating state. The ignition timing of the ignition plug 21 is controlled.
[0030]
The ECU 27 executes the torque control programs shown in FIGS. 12 to 25 to be described later when performing traction control for preventing idling of the drive wheels (slip), fuel cut during deceleration, and the like. In addition to controlling the fuel cut and fuel return (restart of fuel injection) of each cylinder so that the output torque of the cylinder becomes the instructed torque, "torque control" for controlling the ignition timing of each cylinder is performed.
[0031]
Hereinafter, an outline of the torque control executed by the ECU 27 will be described.
When performing the torque control, the ECU 27 selects one mode from the sequential cut mode, the sequential return mode, the all cylinder cut mode, and the all cylinder return mode based on the operating conditions.
[0032]
As shown in FIG. 2, in the sequential cut mode, when the number of fuel cut cylinders of the engine 11 is increased, the normal fuel injection order of each cylinder (# 1 → # 2 → # 4 → # 5 → # 3) is satisfied. A sequential cut is performed in which fuel injection is cut in a predetermined number of cylinders (for example, one cylinder) (in FIG. 2, # 3 → # 2 → # 5 → # 1 → # 4). Further, in the sequential return mode, when the number of fuel cut cylinders of the engine 11 is reduced, the order of skipping a predetermined number of cylinders (for example, one cylinder) with respect to the normal fuel injection order of each cylinder (# 5 → # in FIG. 2) (1 → # 4 → # 3 → # 2), a sequential return to restart the fuel injection is executed. In the present embodiment, the sequential cut mode and the sequential return mode are set to the stability mode in which the stability of the torque control is prioritized.
[0033]
On the other hand, in the all-cylinder cut mode, all-cylinder cut in which fuel injection is cut in the normal fuel injection order of each cylinder to cut fuel injection in all cylinders is executed. In the all-cylinder return mode, all-cylinder return in which fuel injection is restarted in the normal fuel injection order of each cylinder and fuel injection of all cylinders is restarted. In the present embodiment, the all-cylinder cut mode and the all-cylinder return mode are response modes in which the responsiveness of torque control is prioritized.
[0034]
As shown in FIG. 3, generally, there is a delay of, for example, 360 to 720 ° CA from the start of fuel injection to the start of energization of the spark plug. Therefore, during the response mode (all-cylinder cut mode and all-cylinder return mode) operation, the ECU 27 performs the fuel injection amount calculation timing and the ignition timing calculation timing in order to perform torque control with good response to a change in the command torque. Are set immediately before the fuel injection start timing and the spark plug energization start timing, respectively, and as shown in FIG. 4A, at the fuel injection amount calculation timing, the fuel injection amount is set based on the latest instruction torque at that time. Then, at the subsequent ignition timing calculation timing, the ignition timing is calculated based on the latest instruction torque at that time.
[0035]
However, in the torque control method during the response mode operation, as shown in FIG. 4A, when the command torque changes, the command torque value used for calculating the fuel injection amount and the command torque value used for calculating the ignition timing are changed. Therefore, if the amount of the change is large, the fluctuation of the output torque with respect to the command torque becomes large, and unstable torque control may be performed. Therefore, during the stability mode (sequential cut mode and sequential return mode) operation, as in the response mode, the latest instruction torque is used when calculating the fuel injection amount and when calculating the ignition timing, respectively. In spite of the stability mode in which control stability is prioritized, unstable torque control may occur.
[0036]
Therefore, during the stability mode operation, the ECU 27 calculates the fuel injection amount based on the latest command torque at that time at the fuel injection amount calculation timing as shown in FIG. At the timing calculation timing, the ignition timing is calculated based on the past instruction torque calculated before the instruction torque at the ignition timing calculation timing (for example, the instruction torque at the immediately preceding fuel injection amount calculation timing). As a result, the deviation between the command torque used for calculating the fuel injection amount and the command torque used for calculating the ignition timing is reduced (or set to 0), the fluctuation of the output torque with respect to the command torque is reduced, and the stability of torque control is improved. Let it.
[0037]
By the way, as described above, during the stability mode operation, since the ignition timing is calculated based on the past command torque, the responsiveness of the torque control may be reduced. As a countermeasure, the ECU 27 predicts the future rotation speed of the engine 11 during the stability mode operation, calculates the indicated torque based on the future rotation speed, and sets the ignition timing based on the past indicated torque. Even when calculating, the response of the torque control is improved.
[0038]
The future rotation speed is obtained as follows. As shown in FIG. 5, the engine rotation speed Ne is detected by the crank angle sensor 23 at a predetermined cycle (for example, 360 ° A cycle), and the estimated shaft torque T for each cylinder is calculated. According to the method of calculating the estimated shaft torque T for each cylinder, the estimated shaft torque T0 is calculated based on the actual intake air amount detected by the air flow meter 14, and the estimated shaft torque T0 includes the ignition timing efficiency and the presence or absence of fuel injection (1 or 0) to obtain the cylinder-specific estimated shaft torque T.
T = T0 x ignition timing efficiency x presence or absence of fuel injection (1 or 0)
[0039]
The stability mode (sequential cut mode and sequential return mode) is selected when the state of the drive transmission system (gear or clutch) connected to the engine 11 is stable (for example, fuel cut operation during deceleration). The behavior of the subsequent rotational speed Ne is substantially determined by the behavior of the estimated shaft torque T for each cylinder. Therefore, the relationship between the fluctuation amount of the estimated shaft torque T for each cylinder and the fluctuation amount of the rotation speed Ne can be expressed as the following equation.
{Ne (i) -Ne (i-1)} / {T (i-1) -T (i-2)} = {ENe-Ne (i)} / {T (i) -T (i-1) )｝
[0040]
Here, Ne (i-1) is the rotation speed one time before (for example, before 360 ° A), Ne (i) is the current rotation speed, and ENe is the future rotation speed for the next time (for example, after 360 ° A). , T (i-2) is the cylinder estimated shaft torque two times before (for example, 720 ° C. before), T (i-1) is the cylinder shaft estimated one time before (for example, 360 ° A before), T (I) is the current estimated cylinder torque for each cylinder.
[0041]
By solving the above equation for the future rotation speed ENe, the following equation (1) can be obtained.
ENe = {T (i) -T (i-1)} / {T (i-1) -T (i-2)} × {Ne (i) -Ne (i-1)} + Ne (i) ... … (1)
[0042]
The ECU 27 calculates the future rotation speed ENe using the engine rotation speed Ne and the cylinder-specific estimated shaft torque T according to the above equation (1), and calculates the instruction torque based on the future rotation speed ENe during the stability mode operation. I do.
[0043]
Further, as described above, in the response mode, the ignition timing is calculated based on the latest instruction torque, whereas in the stability mode, the ignition timing is calculated based on the past instruction torque. For this reason, as shown in FIG. 6, when switching between the response mode and the stability mode, the command torque used for calculating the ignition timing is switched between the latest command torque and the past command torque (for example, the command torque before three ignitions). If the amount of change is large, the command torque used for calculating the ignition timing changes abruptly, so that the output torque may change suddenly and adversely affect drivability.
[0044]
As a countermeasure, as shown in FIG. 7, when switching between the response mode and the stability mode, the ECU 27 executes a smoothing process for gradually changing the instruction torque used for calculating the ignition timing, thereby making it possible to calculate the ignition timing. A sudden change in the used instruction torque is prevented, and a sudden change in the output torque is prevented.
[0045]
Hereinafter, in the response mode, the ignition timing is calculated based on the latest instruction torque RT (i). In the stability mode, the ignition timing is calculated based on the instruction torque RT (in) before n ignitions (for example, three ignitions before). The case where the ignition timing is calculated will be described.
[0046]
As shown in FIG. 7, in the response mode, the counter value S of the smoothing counter is maintained at the maximum value Smax (for example, 4), and when the mode is switched from the response mode to the stability mode, the smoothing counter is switched every normal ignition interval. The counter value S is decremented by “1”, and is decreased from the maximum value Smax to 0. On the other hand, in the stability mode, the counter value S of the smoothing counter is maintained at 0, and when switching from the stability mode to the response mode, the counter value S of the smoothing counter is incremented by "1" at each normal ignition interval. From 0 to the maximum value Smax.
[0047]
Then, the instruction torque rRT used for calculating the ignition timing is calculated by the following equation.
rRT = RT (in) + {RT (i) -RT (in)} × S / Smax (2)
In the response mode, in order to maintain the counter value S of the smoothing counter at the maximum value Smax, the command torque rRT used for calculating the ignition timing is maintained at the latest command torque RT (i) according to the above equation (2).
[0048]
Further, when switching from the response mode to the stability mode, the counter value S of the smoothing counter is decremented by 1 from the maximum value Smax to 0, and therefore, the command torque rRT used for calculating the ignition timing is calculated by the above equation (2). Gradually changes from the latest command torque RT (i) to the command torque RT (in) before n ignitions.
[0049]
On the other hand, in the stability mode, in order to maintain the counter value S of the smoothing counter at 0, the command torque rRT used for calculating the ignition timing is maintained at the command torque RT (in) before n ignitions, according to the above equation (2). Is done.
[0050]
When the mode is switched from the stability mode to the response mode, the counter value S of the smoothing counter is incremented by “1” from 0 to the maximum value Smax in increments of “1”. Gradually changes from the instruction torque RT (in) before n ignitions to the latest instruction torque RT (i).
[0051]
The expression (2) need not always be used in all modes, and may be used in at least one of switching from the response mode to the stability mode and switching from the stability mode to the response mode.
[0052]
Next, a description will be given of a sequential cut or a sequential return in which fuel injection is cut or restarted in an order skipped by a predetermined number of cylinders with respect to a normal fuel injection order of each cylinder.
[0053]
If the torque generation rate (the ratio of the instruction torque to the output torque when fuel injection is performed in all cylinders) is not the instruction torque itself, it can directly correspond to the number of fuel cut cylinders. For example, in the case of the engine 11 having a total of five cylinders, when the torque generation rate is 0.8 (= 4/5), it is sufficient to cut off the fuel for only one cylinder.
[0054]
Therefore, the ECU 27 reduces or increases the torque generation rate at a constant rate (by a predetermined change amount in a predetermined cycle), and increases or decreases the number of fuel cut cylinders in accordance with the torque generation rate, so that the designated torque (torque generation rate) is reduced. ) Is accurately reflected, and a sequential cut or a sequential return is realized.
[0055]
A predetermined cycle and a predetermined change amount (hereinafter, referred to as a “torque generation rate change amount”) when the torque generation rate is changed at a constant rate are set as follows. In an engine 11 having a total number of cylinders of Y cylinders (where Y is an integer of 3 or more), X cylinders (where X is 1) every n cycles (where n is an integer of 0 or more) with respect to the normal fuel injection order of each cylinder. When executing the sequential cut or the sequential return in the order skipped by the above integers, the predetermined cycle for changing the torque generation rate is set to the normal ignition interval of the engine 11 (= 720 ° C. A / Y). Then, the torque generation rate change amount ΔTCR is set by the following equation (3).
ΔTCR = 1 / Y / (X + 1 + n × Y) (3)
[0056]
Therefore, in the sequential cut mode, the torque generation rate TCRate is reduced by the following equation at each normal ignition interval by a torque generation rate change amount ΔTCR = 1 / Y / (X + 1 + n × Y).
TCrate (i) = TCrate (i-1) -1 / Y / (X + 1 + n * Y)
[0057]
On the other hand, in the sequential return mode, the torque generation rate TCRate is increased by a torque generation rate change amount ΔTCR = 1 / Y / (X + 1 + n × Y) by the following equation at each normal ignition interval.
TCrate (i) = TCrate (i−1) + 1 / Y / (X + 1 + n × Y)
[0058]
Hereinafter, the case where the engine 11 has five cylinders will be described.
In the five-cylinder engine 11, the output torque decreases by 20% each time the number of fuel cut cylinders increases by one cylinder. Therefore, as shown in FIG. 8A, in the sequential cut mode, the determination of the torque generation rate TCrate is performed. The value is set at intervals of 0.2 (for example, 0.8 → 0.6 → 0.4 → 0.2 → 0), and the number of fuel cut cylinders decreases by 1 every time the torque generation rate TCRate decreases by 0.2. It is designed to increase by cylinder.
[0059]
In addition, in the five-cylinder engine 11, the output torque increases by 20% each time the number of fuel return cylinders (5-fuel cut cylinder number) increases by one cylinder. Therefore, as shown in FIG. In the return mode, the determination value of the torque generation rate TCRate is set at intervals of 0.2 (for example, 0 → 0.2 → 0.4 → 0.6 → 0.8), and the torque generation rate TCRate is only 0.2. Each time the number of cylinders is increased, the number of fuel return cylinders is increased by one cylinder.
[0060]
Note that the determination value of the torque generation rate TCRate in each mode is an appropriate factor. For example, when 0 <TCrate ≦ 0.2, misfire occurs beyond the adjustment range when adjusting the torque at the ignition retard angle. In the case of the sequential cut mode, the number of fuel cut cylinders may be set to 5 in a range of TCrate ≦ 0.1 in the case of the sequential cut mode.
[0061]
When the engine 11 having five cylinders performs the sequential cut or the sequential return in the order of skipping one cylinder at a time every 0 cycles (that is, every cycle) with respect to the normal fuel injection order of each cylinder. Substitutes Y = 5, n = 0, and X = 1 into the above equation (3) to determine the torque generation rate change amount ΔTCR.
ΔTCR = 1/5 / (1 + 1 + 0 × 5) = 0.1
[0062]
By setting the torque generation rate change amount ΔTCR in this way, as shown in FIG. 9, the torque generation rate TCRate can be decreased or increased by 0.1 for each ignition, so that every two ignitions (that is, The torque generation rate is 0.2 (that is, the torque generation rate corresponding to fuel cut or fuel return for one cylinder of the five-cylinder engine 11) in increments of one cylinder at a time with respect to the normal fuel injection order. It can be reduced or increased. Thus, the five-cylinder engine 11 can execute the sequential cut or the sequential return in the order in which the cylinders are skipped one by one with respect to the normal fuel injection order of each cylinder.
[0063]
By the way, when the torque generation rate change amount ΔTCR is calculated by the above equation (3), the calculation result of the torque generation rate change amount ΔTCR becomes an infinite decimal number as in the case where the total number of cylinders is three or six. Sometimes. For example, in the engine 11 having a total number of six cylinders, the sequential cut or the sequential return is executed in the order in which the cylinders are skipped one by one every 0 cycles (that is, every cycle) with respect to the normal fuel injection order of each cylinder. In this case, when the torque generation rate change ΔTCR is calculated by substituting Y = 6, n = 0, and X = 1 into the above equation (3), the torque generation rate change ΔTCR becomes an infinite decimal number as follows. Become.
ΔTCR = 1/6 / (1 + 1 + 0 × 6) = 0.08333
[0064]
Therefore, as shown in FIG. 10A, first, the number of digits after the decimal point of the determination value of the torque generation rate TCRate is set so as not to cause a problem in control, and then the decimal point of the torque generation rate change amount ΔTCR is set. The torque generation rate change amount ΔTCR is set to, for example, 0.0833 by the round-down method so that the following digits are equal to the determination value. However, if the torque generation rate change amount ΔTCR is set by the truncation method, when the torque generation rate TCRate is decreased by the torque generation rate change amount ΔTCR (for example, 0.0833) in order to perform the sequential cut, the torque generation rate TCRate is set. Is insufficient, and the timing for increasing the number of fuel cut cylinders is shifted.
[0065]
Therefore, as shown in FIG. 10B, the torque generation rate change ΔTCR is set to, for example, 0.0834 by the round-up method so that the number of decimal places of the torque generation rate change ΔTCR becomes the same as the determination value. Need to be done. When the torque generation rate change amount ΔTCR is set in the round-up method as described above, when the torque generation rate TCRate is decreased by the torque generation rate change amount ΔTCR (for example, 0.0834) in order to perform the sequential cut, the torque generation rate is changed. The minimum value of TCrate becomes a negative value. Therefore, in order to prevent the torque generation rate TCRate from becoming a negative value, it is conceivable to perform a guard process by setting the minimum value of the torque generation rate TCRate to 0.
[0066]
However, if the minimum value of the torque generation rate TCRate is guarded by 0, then the torque generation rate TCRate is changed from the guarded minimum value (0) to the torque generation rate change amount ΔTCR (for example, 0) in order to perform sequential return. 0.0834), the timing of increasing the number of fuel return cylinders may be shifted. In addition, the case where the torque generation rate TCRate is subjected to the guard processing and the case where the guard processing is not performed (the case where the torque generation rate TCRate is increased before the torque generation rate TCRate is reduced to the minimum value due to a change in the operating conditions). Therefore, there is also a problem that the torque generation rates become different values.
[0067]
As a countermeasure, as shown in FIG. 10 (c), the torque generation rate TCRate used for determining the number of fuel cut cylinders and the number of fuel return cylinders is not subjected to guard processing, and is used as it is even if it takes a negative value. It is good to treat it as 0 at the stage of conversion into a control value. In this manner, the sequential cut and the sequential return can be performed without shifting the timing of increasing the number of fuel cut cylinders and the number of fuel return cylinders. Further, by increasing the number of digits of the torque generation rate change amount ΔTCR to be larger than the number of digits of the determination value of the torque generation rate TCRate, it is possible to prevent the accuracy from being deteriorated during integration.
[0068]
By the way, even if the torque generation rate TCRate is changed at a constant rate (by a predetermined change amount in a predetermined cycle) so as to perform a sequential cut or a sequential return, the fuel injection amount calculation timing (that is, the fuel cut or the fuel cutoff in accordance with the torque generation rate TCRate). When the fuel return timing changes, the change in the torque generation rate TCRate received at each fuel injection amount calculation timing may not be constant, and the fuel cut order and the fuel return order may be disturbed. Further, if the fuel injection timing is not fixed, it is difficult to determine in advance whether fuel cut or fuel return is in time, and it becomes difficult to specify a cylinder to be fuel cut or fuel returned next.
[0069]
As a countermeasure, the ECU 27 fixes the fuel injection amount calculation timing and the fuel injection timing in the stability mode (sequential cut mode and sequential return mode). For example, as shown in FIG. 11A, during sequential cut, the fuel injection amount calculation timing is fixed two ignitions before the ignition timing calculation timing, and at the time of sequential recovery, the fuel injection amount calculation timing is three ignitions before the ignition timing calculation timing. The injection amount calculation timing is fixed. The fuel injection timing is fixed immediately after each fuel injection amount calculation timing.
[0070]
In this case, the required fuel injection amount changes depending on the engine operating state such as the engine rotation speed, the engine temperature, and the load. Therefore, the fuel injection amount calculation timing and the fuel injection timing should be set to timings allowing injection with some allowance. The point is that once in the stability mode, the fuel injection amount calculation timing and the fuel injection timing need not be changed during the stability mode operation. The first fuel injection amount calculation timing and the fuel injection timing may be set by assuming a subsequent change in the engine operating state. Even if it is assumed that the engine operation state will change afterwards, it is sufficient to consider the operation state in which the stability mode should be continued, so if the accelerator is depressed or there is a sharp decrease in the rotation speed, the smoothing process will also be bypassed. Since these should be switched to the response mode, these cases do not need to be considered.
[0071]
The torque control by the ECU 27 described above is executed in accordance with the torque control programs shown in FIGS. Hereinafter, the processing contents of these programs will be described.
[0072]
[Future rotation speed calculation]
The future rotation speed calculation program shown in FIG. 12 is executed at a predetermined cycle (for example, 360 ° A cycle). When this program is started, first, in step 101, the engine rotation speed Ne detected by the crank angle sensor 23 is read.
[0073]
Thereafter, the routine proceeds to step 102, where the estimated shaft torque T0 is calculated based on the intake air amount detected by the air flow meter 14, and the estimated shaft torque T0 is multiplied by the ignition timing efficiency and the presence or absence of fuel injection (1 or 0). To obtain an estimated shaft torque T for each cylinder. The processing of step 102 serves as a shaft torque calculating means referred to in the claims.
[0074]
Thereafter, the routine proceeds to step 103, where the future rotational speed ENe is calculated by the following equation.
ENe = {T (i) -T (i-1)} / {T (i-1) -T (i-2)} × {Ne (i) -Ne (i-1)} + Ne (i)
The processing in step 103 plays a role as a future rotation speed prediction means in the claims.
[0075]
[Calculation of torque generation rate]
The torque generation rate calculation program shown in FIG. 13 is executed at regular ignition intervals (for example, at 144 ° C. in the case of a five-cylinder engine). When this program is started, first, in step 201, it is determined whether or not the torque cut mode TCMode is set to “1”.
[0076]
The torque cut mode TCMode is set to one of “1”, “2”, “3”, and “0” by a torque cut mode determination program (not shown). The torque cut mode TCMode = 1 means the sequential cut mode, and the torque cut mode TCMode = 2 means the all cylinder cut mode. Further, the torque cut mode TCMode = 3 means the sequential return mode, and the torque cut mode TCMode = 0 means the all cylinder return mode.
[0077]
For example, when all the deceleration fuel cut / return conditions such as the idling state, the gear is not neutral, and the engine rotation speed Ne is higher than a predetermined rotation speed are satisfied, the stability of the torque control should be prioritized. It is determined that the state is the state, and the torque cut mode TCMode = 1 is set to select the sequential cut mode. Alternatively, the torque recovery mode TCMode is set to 3, and the sequential return mode is selected.
[0078]
On the other hand, when the deceleration fuel cut / return condition is not satisfied, it is determined that the responsiveness of the torque control should be given priority, and the torque cut mode TCMode is set to 2 to select the all cylinder cut mode. Alternatively, the torque cut mode TCMode = 0 is set and the all-cylinder return mode is selected.
[0079]
In step 201, it is determined whether or not the sequential cut mode is selected based on whether or not the torque cut mode TCMode is set to “1”, and the sequential cut mode is selected (torque cut mode TCMode = If determined as 1), the process proceeds to step 202, where it is determined whether or not the previous time was also the sequential cut mode.
[0080]
When it is determined that the previous time is not the sequential cut mode, that is, in the case of the first processing after switching to the sequential cut mode, the process proceeds from step 202 to step 203, where the torque generation rate TCrate is set to “1”. , Proceed to step 204.
[0081]
On the other hand, if it is determined in the step 202 that the previous time is also the sequential cut mode, that is, the second and subsequent times after switching to the sequential cut mode, the process proceeds from the step 202 to the step 204.
[0082]
In step 204, the torque generation rate TCRate is reduced by the change amount ΔTCR of the torque generation rate TCRate according to the following equation. However, the minimum value of the torque generation rate TCrate is 0.
TCRate = TCRate-ΔTCR
[0083]
Here, in the engine 11 having the total number of cylinders of 5, the sequential cut or the sequential return is performed every 0 cycles (that is, every cycle) with respect to the normal fuel injection order of each cylinder in the order of skipping one cylinder at a time. When executing, the torque generation rate change amount ΔTCR is set by substituting Y = 5, n = 0, and X = 1 into the following equation.
ΔTCR = 1 / Y / (X + 1 + n × Y)
= 1/5 / (1 + 1 + 0 × 5) = 0.1
[0084]
Thus, in the sequential cut mode, the torque generation rate TCRate is reduced by 0.1 for each ignition, and the torque is generated for every two ignitions (that is, in the order of skipping one cylinder at a time with respect to the normal fuel injection order). The rate TCRate is decreased by 0.2 (that is, a torque generation rate corresponding to a fuel cut for one cylinder of the five-cylinder engine 11).
[0085]
On the other hand, if it is determined in step 201 that the sequential cut mode is not selected (torque cut mode TCMode # 1), the process proceeds to step 205, and whether the torque cut mode TCMode is set to "2" is determined. Thus, it is determined whether or not the all-cylinder cut mode is selected.
[0086]
If it is determined in step 205 that the all-cylinder cut mode is selected (torque cut mode TCMode = 2), the process proceeds to step 206, where the torque generation rate TCrate is set to “0”.
TCrate = 0
[0087]
If it is determined in step 205 that the all-cylinder cut mode is not selected (torque cut mode TCMode # 2), the process proceeds to step 207, and whether the torque cut mode TCMode is set to "3" is determined. Whether or not the sequential return mode has been selected is determined depending on whether or not it is determined.
[0088]
If it is determined in step 207 that the sequential return mode has been selected (torque cut mode TCMode = 3), the process proceeds to step 208, where the torque generation rate TCrate is increased by the torque generation rate change amount ΔTCR according to the following equation. However, the maximum value of the torque generation rate TCrate is 1.
TCrate = TCrate + ΔTCR
[0089]
Thus, in the sequential return mode, the torque generation rate TCRate is increased by 0.1 for each ignition, and the torque is generated for every two ignitions (that is, in the order of skipping one cylinder at a time with respect to the normal fuel injection order). The rate TCRate is increased by 0.2 (that is, a torque generation rate corresponding to fuel return for one cylinder of the five-cylinder engine 11).
[0090]
When it is determined in step 207 that the sequential return mode is not selected (torque cut mode TCMode # 3), it is determined that the all-cylinder return mode is selected (torque cut mode TCMode = 0). Then, the routine proceeds to step 209, where the torque generation rate TCrate is set to "1".
TCrate = 1
[0091]
[Instruction indicated torque calculation]
The indicated indicated torque calculation program shown in FIG. 14 is executed at each normal ignition interval, and plays a role as indicated torque calculation means in claims. When this program is started, first, in step 301, it is determined whether or not the torque generation rate TCrate is “1”.
[0092]
If the torque generation rate TCRate is "1", that is, in the case of the all-cylinder return mode, the routine proceeds to step 302, where a loss torque (torque according to the load of external accessories, etc.) is added to the driver-specified shaft torque. The designated indicated torque RITrq is obtained.
RITrq = driver indicated shaft torque + loss torque
[0093]
On the other hand, if the torque generation rate TCRate is not "1", that is, if the sequential cut mode, the sequential return mode, or the all-cylinder cut mode, the process proceeds to step 303, where the map is generated based on the future rotational speed ENe and the intake air amount. After calculating the estimated indicated torque EITrq in the case where fuel is injected in all cylinders, the process proceeds to step 304, and the indicated indicated torque RITrq is obtained by multiplying the estimated indicated torque EITrq by the torque generation rate TCRate.
RITrq = EITRq × TCrate
[0094]
[Fuel cut / return decision]
The fuel cut / return determination program shown in FIGS. 15 and 16 is executed at each normal ignition interval, and plays a role as a fuel injection amount calculation means referred to in the claims. When the program is started, first, in step 401, it is determined whether or not the estimated indicated torque EITrq ≠ 0. If it is determined that the estimated indicated torque EITrq = 0, in order to prevent a division by zero, Proceeding to step 402, the torque ratio rTrate is set to "1".
[0095]
On the other hand, if it is determined in step 401 that the estimated indicated torque EITrq ≠ 0, the process proceeds to step 403, where the indicated indicated torque RITrq is divided by the estimated indicated torque EITrq to obtain a torque ratio rTrate (= torque generation rate TCRate). Ask.
rTRate = RITrq / EITRq
[0096]
Thereafter, the routine proceeds to step 404, where it is determined whether or not the torque cut mode TCMode = 1 (sequential cut mode). If the torque cut mode TCMode is the sequential cut mode, the routine proceeds to step 405, where the fuel cut cylinder order shown in FIG. Execute the setting program.
[0097]
Thereafter, the process proceeds to step 406, where it is determined whether or not the torque cut mode TCMode = 3 (sequential return mode). If the mode is the sequential return mode, the process proceeds to step 407, and the fuel return cylinder order shown in FIG. Execute the setting program.
[0098]
Thereafter, the process proceeds to step 408 in FIG. 16, and the injection rate rIRate is calculated by the following equation using the total number of cylinders Y (for example, 5) and the current number of fuel cut cylinders FCL.
rIRate = (5-FCL) / 5
[0099]
Then, in the next step 409, it is determined whether or not the torque cut mode TCMode = 1 (sequential cut mode). If the mode is the sequential cut mode, the process proceeds to step 410, where a sequential fuel cut process shown in FIG. The program is executed to perform a sequential cut in which fuel injection is cut in a sequence skipped by a predetermined number of cylinders (for example, one cylinder) with respect to a normal fuel injection sequence of each cylinder.
[0100]
Thereafter, the process proceeds to step 411, where it is determined whether or not the torque cut mode TCMode = 3 (sequential return mode). If the mode is the sequential return mode, the process proceeds to step 412, where a sequential fuel return process shown in FIG. The program is executed to perform a sequential return in which fuel injection is restarted in the order in which a predetermined number of cylinders (for example, one cylinder) are skipped in the normal fuel injection order of each cylinder.
[0101]
Then, in the next step 413, it is determined whether or not the torque cut mode TCMode = 2 (all cylinder cut mode). If it is the all cylinder cut mode, the process proceeds to step 414 to execute the all cylinder fuel cut process. Then, the fuel injection is cut in the normal fuel injection order of each cylinder to cut the fuel injection of all cylinders.
[0102]
Thereafter, the process proceeds to step 415, where it is determined whether or not the torque cut mode TCMode is 0 (all cylinders return mode). If the mode is the all cylinders return mode, the process proceeds to step 416 to execute the all cylinder fuel return process. Then, fuel injection is resumed in the normal fuel injection order of each cylinder, and fuel injection of all cylinders is resumed.
[0103]
Then, in the last step 417, after calculating the current number of fuel cut cylinders FCL, the present program is ended.
[0104]
[Set fuel cut cylinder order]
When the fuel cut cylinder order setting program (step 405 in FIG. 15) shown in FIG. 17 is started, first, in step 501, the count value (crank rotation position) of the crank counter CCunt is read. As shown in FIG. 11B, the crank counter CCunt is incremented by “1” every 36 ° C., so that 4 counts of the crank counter CCnt correspond to a normal ignition interval (144 ° C.), Twenty counts of the crank counter CCnt correspond to one cycle (720 ° C.). Note that the crank counter CCunt is reset to “0” when it reaches “20”.
[0105]
Further, the crank rotation position of the crank counter CCunt = 0 is equivalent to the ignition timing calculation timing of # 5, and the crank rotation positions of the crank counter CCunt = 4, 8, 12, and 16 are # 3, # 1, and # 2, respectively. , And # 4.
[0106]
First, in step 501, the count value (crank rotation position) of the crank counter CCunt is read, and then in step 502, it is determined whether or not the crank counter CCunt = 0 (ignition timing calculation timing of # 5). As a result, if it is determined that the crank counter CCnt = 0 (ignition timing calculation timing of # 5), the process proceeds to step 503, where rCylord (1) = 3, rCylord (2) = 1, rCylord (3) = 2. By setting rCylord (4) = 4 and rCylord (5) = 5, the priority order of the cylinders to be fuel cut is set in the order of # 3, # 1, # 2, # 4, # 5.
[0107]
On the other hand, if it is determined in step 502 that the crank counter CCunt is not 0 (ignition timing calculation timing of # 5), the process proceeds to step 504, and the crank counter CCunt = 4 (ignition timing calculation timing of # 3). Is determined. If it is determined that the crank counter CCunt = 4 (ignition timing calculation timing of # 3), the process proceeds to step 505, where rCylord (1) = 1, rCylord (2) = 2, rCylord (3) = 4, rCylord ( 4) = 5, rCylord (5) = 3, so that the priority order of the cylinders for which fuel is cut is set in the order of # 1, # 2, # 4, # 5, # 3.
[0108]
If it is determined in step 504 that the crank counter CCunt is not 4 (ignition timing calculation timing of # 3), the process proceeds to step 506, and the crank counter CCunt = 8 (ignition timing calculation timing of # 1). Is determined. As a result, if it is determined that the crank counter CCunt = 8 (ignition timing calculation timing of # 1), the process proceeds to step 507, where rCylord (1) = 2, rCylord (2) = 4, rCylord (3) = 5. By setting rCylord (4) = 3 and rCylord (5) = 1, the priority order of the cylinders for fuel cut is set in the order of # 2, # 4, # 5, # 3, # 1.
[0109]
If it is determined in step 506 that the crank counter CCunt is not 8 (ignition timing calculation timing of # 1), the process proceeds to step 508, and the crank counter CCunt = 12 (ignition timing calculation timing of # 2). Is determined. As a result, if it is determined that the crank counter CCunt = 12 (ignition timing calculation timing of # 2), the process proceeds to step 509, where rCylord (1) = 4, rCylord (2) = 5, rCylord (3) = 3. By setting rCylord (4) = 1 and rCylord (5) = 2, the priority order of the cylinders to be fuel cut is set in the order of # 4, # 5, # 3, # 1, # 2.
[0110]
If it is determined in step 508 that the crank counter CCunt is not 12 (ignition timing calculation timing of # 2), it is determined that the crank counter CCunt = 16 (ignition timing calculation timing of # 4). Proceeding to step 510, by setting rCylord (1) = 5, rCylord (2) = 3, rCylord (3) = 1, rCylord (4) = 2, rCylord (5) = 4, the cylinder of the fuel cut cylinder is set. The priorities are set in the order of # 5, # 3, # 1, # 2, # 4.
[0111]
[Fuel return cylinder setting]
When the fuel return cylinder order setting program (step 407 in FIG. 15) shown in FIG. 18 is started, first, in step 601, the count value (crank rotation position) of the crank counter CCunt is read, and then the process proceeds to step 602. It is determined whether or not crank counter CCunt = 8 (ignition timing calculation timing of # 1). As a result, if it is determined that the crank counter CCunt = 8 (ignition timing calculation timing of # 1), the process proceeds to step 603, where rCylord (1) = 4, rCylord (2) = 5, rCylord (3) = 3. By setting rCylord (4) = 1 and rCylord (5) = 2, the priority order of the cylinders that return fuel is set in the order of # 4, # 5, # 3, # 1, # 2.
[0112]
On the other hand, if it is determined in step 602 that the crank counter CCunt is not 8 (ignition timing calculation timing of # 1), the process proceeds to step 604, and the crank counter CCunt = 12 (ignition timing calculation timing of # 2). Is determined. As a result, if it is determined that the crank counter CCunt = 12 (ignition timing calculation timing of # 2), the process proceeds to step 605, where rCylord (1) = 5, rCylord (2) = 3, rCylord (3) = 1. By setting rCylord (4) = 2 and rCylord (5) = 4, the priority order of the cylinders that return fuel is set in the order of # 5, # 3, # 1, # 2, # 4.
[0113]
If it is determined in step 604 that the crank counter CCunt is not 12 (ignition timing calculation timing of # 2), the process proceeds to step 606, and the crank counter CCunt = 16 (ignition timing calculation timing of # 4). It is determined whether or not. As a result, when it is determined that the crank counter CCunt = 16 (ignition timing calculation timing of # 4), the process proceeds to step 607, where rCylord (1) = 3, rCylord (2) = 1, and rCylord (3). = 2, rCylord (4) = 4, and rCylord (5) = 5, the priority order of the cylinders that return fuel is set in the order of # 3, # 1, # 2, # 4, and # 5.
[0114]
If it is determined in step 606 that the crank counter CCunt is not 16 (ignition timing calculation timing of # 4), the process proceeds to step 608, where crank counter CCunt = 0 (ignition timing calculation timing of # 5). It is determined whether or not. As a result, when it is determined that the crank counter CCunt = 0 (ignition timing calculation timing of # 5), the process proceeds to step 609, where rCylord (1) = 1, rCylord (2) = 2, and rCylord (3). By setting = 4, rCylord (4) = 5, and rCylord (5) = 3, the priority order of the cylinders that return fuel is set in the order of # 1, # 2, # 4, # 5, and # 3.
[0115]
If it is determined in step 608 that the crank counter CCunt is not 0 (ignition timing calculation timing of # 5), it is determined that crank counter CCunt = 4 (ignition timing calculation timing of # 3), and step 610 is determined. By setting rCylord (1) = 2, rCylord (2) = 4, rCylord (3) = 5, rCylord (4) = 3, and rCylord (5) = 1, the priority order of the cylinders returning to fuel is set. Are set in the order of # 2, # 4, # 5, # 3, # 1.
[0116]
[Sequential fuel cut processing]
When the sequential fuel cut processing program (step 410 in FIG. 16) shown in FIG. 19 is started, first, in step 701, a value obtained by subtracting 0.2 from the injection rate rIRate is equal to or more than the torque ratio rTRate (rIRate−0.2). ≧ rTrate) is determined. If it is determined that rIRate-0.2 <rTrate, the program ends.
[0117]
Thereafter, when it is determined that rIRate−0.2 ≧ rTrate, the routine proceeds to step 702, where a cylinder-specific fuel cut request rCCReq {rCylord (n)} is set to “0” meaning fuel return, and The cylinder-based intake fuel amount rIFel {rCylord (n)} is 0. Among rCylord (n), the one with the highest priority is selected as the fuel cut cylinder. During the subsequent stability mode (sequential cut mode) operation, the fuel injection amount calculation timing and the fuel injection timing are fixed.
[0118]
Thereafter, the routine proceeds to step 703, where the cylinder-specific fuel cut request rCCReq {rCylord (n)} is set to "1" indicating the fuel cut for the rCylord (n) selected in step 702, and then proceeds to step 704. , The injection rate rIRate is reduced by 0.2.
[0119]
In the sequential cut mode, the torque ratio rTRate (= torque generation rate TCRate) is reduced by 0.1 for each ignition, and the torque ratio rTRate is reduced by 0.2 for each two ignitions. Every time (that is, in the order of skipping one cylinder at a time with respect to the normal fuel injection order), a sequential cut in which the number of fuel cut cylinders is increased one by one can be executed.
[0120]
[Sequential fuel return processing]
When the sequential fuel return processing program (step 412 in FIG. 16) shown in FIG. 20 is started, first, in step 801, it is determined whether the torque ratio rTrate is equal to or more than the injection rate rIRate (rTrate ≧ rIRate). As a result, if it is determined that rTrate <rIRate, the program ends.
[0121]
Thereafter, when it is determined that rTRate ≧ rIRate, the routine proceeds to step 802, where the cylinder-specific fuel cut request rCCReq {rCylord (n)} is set to “1” meaning fuel cut rCylord (n) Among them, the one with the highest priority is selected as the fuel return cylinder. During the subsequent stability mode (sequential return mode) operation, the fuel injection amount calculation timing and the fuel injection timing are fixed.
[0122]
Thereafter, the routine proceeds to step 803, where the cylinder-specific fuel cut request rCCReq {rCylord (n)} is set to "0", which means fuel return, for the rCylord (n) selected at step 802, and then proceeds to step 804. , Increase the injection rate rIRate by 0.2.
[0123]
In the sequential return mode, the torque ratio rTRate (= torque generation rate TCRate) is increased by 0.1 for each ignition, and the torque ratio rTRate is increased by 0.2 for every two ignitions. Every time (that is, in the order of skipping one cylinder at a time with respect to the normal fuel injection order), a sequential return in which the number of fuel return cylinders is increased one by one can be executed.
[0124]
The fuel cut cylinder order setting program shown in FIG. 17, the fuel return cylinder order setting program shown in FIG. 18, the sequential fuel cut program shown in FIG. 19, and the sequential fuel return program shown in FIG. It serves as a sequential control means.
[0125]
[Calculation of ignition timing retard amount]
The ignition timing retard amount calculation program shown in FIG. 21 is executed at regular ignition intervals, and plays a role as ignition timing calculation means described in the claims. When the program is started, first, in step 901, it is determined whether or not the torque cut mode TCMode is 1 (sequential cut mode). If it is the sequential cut mode, the process proceeds to step 902, and FIG. The sequential cut processing program shown in FIG.
[0126]
Thereafter, the process proceeds to step 903, where it is determined whether or not the torque cut mode TCMode = 3 (sequential return mode). If the mode is the sequential return mode, the process proceeds to step 904 to execute a sequential return processing program shown in FIG. Execute
[0127]
Then, in the next step 905, it is determined whether or not the torque cut mode TCMode = 0 or 2 (all cylinder return mode or all cylinder cut mode). Proceeding to 906, the all cylinder return or all cylinder cut processing program shown in FIG.
[0128]
Thereafter, the process proceeds to step 907, in which the value of rTCMode (old) is updated with the current TCMode, and then the process proceeds to step 908, where the ignition timing is determined by using an instruction torque rRTrq, an estimated torque rETrq, and the number of fuel cut cylinders rCL described later. The torque ratio rTrate for calculating the retard amount is calculated by the following equation.
rTRate = rRTrq / {rETrq × (5-rCL) / 5}
[0129]
Then, in the next step 909, after executing the previous value update processing program shown in FIG. 25, the process proceeds to step 910, in which a map of the ignition timing retard amount TCRert shown in FIG. 26 is searched, and the map corresponding to the torque ratio rTrate is retrieved. An ignition timing retard amount TCRert is obtained.
[0130]
[Sequential cut processing]
When the sequential cut processing program (step 902 in FIG. 21) shown in FIG. 22 is started, first, in step 1001, it is determined whether or not rTCMode (Old) = 0 (previous is all-cylinder return mode). If the previous time was determined to be the all-cylinder return mode, that is, the first time after switching to the sequential cut mode, the process proceeds to step 1002, and the counter value of the smoothing counter SCnt is set to the maximum value Smax (for example, 3).
[0131]
Thereafter, the process proceeds to step 1003, where 3 is the initial value of the instruction torque rRTrq (old3) before ignition, 2 is the initial value of the instruction torque rRTrq (old2) before ignition, and 1 is the initial value of the instruction torque rRTrq (old) before ignition. , Set the current indicated indicated torque RITrq. These values of rRTrq (old3), rRTrq (old2) and rRTrq (old) are updated by a previous value update processing program shown in FIG.
[0132]
Thereafter, the process proceeds to step 1004, where the initial value of the estimated torque rETrq (old3) before 3 ignitions, the initial value of the estimated torque rETrq (old2) before 2 ignitions, and the initial value of the estimated torque rETrq (old) before 1 ignition are determined. , Set the current estimated indicated torque EITrq. The values of rETrq (old3), rETrq (old2) and rETrq (old) are updated by a previous value update processing program shown in FIG.
[0133]
On the other hand, if it is determined in step 1001 that the previous time is not the all-cylinder return mode, that is, from the second time after switching to the sequential cut mode, the process proceeds to step 1005, and the counter value of the smoothing counter SCnt is set to “1”. It is decremented (however, SCnt = 0 is set to the minimum value).
[0134]
Thereafter, the process proceeds to step 1006, where, for example, when the fuel injection amount calculation timing at the time of the sequential cut is two ignitions before the ignition timing calculation timing, the instruction torque rRTrq used for calculating the ignition timing retard amount is calculated by the following equation.
rRTrq = rRTrq (old2) + {rRITrq−rRTrq (old2)} × SCnt / 3
[0135]
Thus, when switching from the all-cylinder return mode (response mode) to the sequential cut mode (stability mode), the counter value of the smoothing counter SCnt is decremented by 1 from the maximum value Smax (for example, 3) to 0. Therefore, the command torque rRTrq used for calculating the ignition timing retard amount by the above equation gradually changes from the latest commanded indicated torque rRITrq to the command torque rRTrq (old2) two ignitions before, and during the stability mode, In order to maintain the counter value of the smoothing counter SCnt at 0, the command torque rRTrq used for calculating the ignition timing retard amount by the above equation is the command torque rRTrq (old2) before two ignitions, that is, the command used for calculating the fuel injection amount. The torque is maintained. The process of step 1006 plays a role as a command torque gradually changing means referred to in the claims.
[0136]
Thereafter, the process proceeds to step 1007, in which the estimated torque rETrq used for calculating the ignition timing retard amount is set to the estimated torque rETrq (old2) before two ignitions, and then the process proceeds to step 1008, which is used for calculating the ignition timing retard amount. The fuel cut cylinder number rCL is set to the fuel cut cylinder number rCL (old) one ignition before.
[0137]
[Sequential return processing]
When the sequential return processing program (step 904 in FIG. 21) shown in FIG. 23 is started, in step 1101, for example, if the fuel injection amount calculation timing at the time of sequential return is three ignitions before the ignition timing calculation timing, the ignition timing The instruction torque rRTrq used for calculating the retard amount is set to the instruction torque rRTrq (old3) before ignition, that is, the instruction torque used for calculating the fuel injection amount, and the estimated torque rETrq used for calculating the ignition timing retard amount is set to 3. The estimated torque rETrq (old3) before ignition is set, and the number rCL of fuel cut cylinders used for calculating the ignition timing retard amount is set to the number rCL (old) of fuel cut cylinders before one ignition.
[0138]
[All cylinder return or all cylinder cut processing]
When the all cylinder return or all cylinder cut processing program (step 906 in FIG. 21) shown in FIG. 24 is started, in step 1201, the instruction torque rRTrq used for calculating the ignition timing retard amount is changed to the current instruction indicated torque RITrq. It sets the estimated torque rETrq used for calculating the ignition timing retard amount to the current estimated indicated torque EITrq, and sets the fuel cut cylinder number rCL used for calculating the ignition timing retard amount to the current fuel cut cylinder number FCL. set.
[0139]
[Previous value update process]
When the previous value update processing program (step 909 in FIG. 21) shown in FIG. 25 is started, first, in step 1301, the instruction torque rRTrq (old3) before three ignitions is changed to the instruction torque rRTrq (old2) before two ignitions. The instruction torque rRTrq (old2) before the second ignition is updated with the instruction torque rRTrq (old) before the first ignition, and the instruction torque rRTrq (old) before the first ignition is updated with the current indicated indicated torque RITrq.
[0140]
Thereafter, the routine proceeds to step 1302, where the estimated torque rETrq (old3) before three ignitions is updated with the estimated torque rETrq (old2) before two ignitions, and the estimated torque rETrq (old2) before two ignitions is estimated for one ignition before. While updating with rETrq (old), the estimated torque rETrq (old1) one ignition before is updated with the current estimated indicated torque EITrq.
[0141]
Thereafter, the routine proceeds to step 1303, where the fuel cut cylinder number rCL is updated with the current fuel cut cylinder number FCL, and the program ends.
[0142]
According to the present embodiment described above, in response modes (all-cylinder cut mode and all-cylinder return mode) in which the responsiveness of torque control is prioritized, the fuel injection amount calculation timing is based on the latest instruction torque at that time. The fuel injection amount is calculated, and at the subsequent ignition timing calculation timing, the ignition timing is calculated based on the latest instruction torque at that time, so that torque control with good response to a change in the instruction torque is performed. be able to.
[0143]
However, in the stability mode (sequential cut mode and sequential return mode) where the stability of torque control is prioritized, the latest instruction torque is calculated when calculating the fuel injection amount and when calculating the ignition timing, as in the response mode. If this is used, the command torque value used for calculating the fuel injection amount and the command torque value used for calculating the ignition timing will be different. Therefore, as shown in the simulation result of FIG. (Output torque) may vary, leading to unstable torque control.
[0144]
Therefore, in the present embodiment, in the stability mode, the fuel injection amount is calculated based on the latest instruction torque at that time at the fuel injection amount calculation timing, and at the subsequent ignition timing calculation timing, the fuel injection amount is calculated at the ignition timing calculation timing. Since the ignition timing is calculated based on the past command torque calculated before the command torque (for example, the command torque at the immediately preceding fuel injection amount calculation timing), the command torque and the ignition used for the fuel injection amount calculation are calculated. The deviation from the command torque used for timing calculation can be reduced (or set to 0), and as shown in the simulation result of FIG. 28, the variation of the cylinder-based total estimated torque (output torque) with respect to the command torque is reduced. Thus, stable torque control can be realized.
[0145]
Note that the command torque used for calculating the ignition timing is not limited to the command torque at the fuel injection amount calculation timing, but may be the past command torque calculated before the command torque at the ignition timing calculation timing. The command torque before and after the command torque at the calculation timing may be used.
[0146]
In the stability mode, since the ignition timing is calculated based on the past command torque, as shown in FIG. 28, there is a possibility that the responsiveness of the cylinder-based total estimated torque (output torque) to the command torque may decrease. In the present embodiment, the future rotation speed of the engine 11 is predicted during the stability mode operation, and the instruction torque is calculated based on the future rotation speed. Is taken into account, and the responsiveness of the torque control can be improved even when the ignition timing is calculated based on the past command torque.
[0147]
Further, the future rotational speed can be obtained by integrating the shaft torque of the engine 11, but using the integration increases the calculation load of the ECU 17. In this regard, in the present embodiment, the future rotation speed is calculated using the rotation speed detected by the crank angle sensor 23 and the shaft torque calculated based on the intake air amount. In addition, the future rotational speed can be calculated with high accuracy, and integration becomes unnecessary, and the calculation load of the ECU 27 can be reduced.
[0148]
However, the calculation method of the future rotation speed may be appropriately changed, and the future rotation speed may be obtained by integrating the shaft torque of the engine 11.
Further, it is not always necessary to calculate the instruction torque based on the future rotation speed, and the calculation method of the instruction torque may be appropriately changed such that the instruction torque may be calculated based on the current rotation speed.
[0149]
Further, in the present embodiment, when switching between the response mode and the stability mode, the command torque used for calculating the ignition timing is gradually changed. Therefore, when switching between the response mode and the stability mode, the ignition timing is changed. It is possible to prevent the command torque used for the calculation from changing suddenly, and prevent the output torque from changing suddenly, thereby preventing the drivability from deteriorating.
[0150]
Further, in the present embodiment, in the engine 11 in which the total number of cylinders is Y (where Y is an integer of 3 or more), every n cycles (where n is an integer of 0 or more) with respect to the normal fuel injection order of each cylinder. When sequential cut or sequential return is executed in the order skipped by X cylinders (where X is an integer of 1 or more), a predetermined cycle for changing the torque generation rate is set to a normal ignition interval (= 720 ° C. A / Y). , And the predetermined amount of change is set to 1 / Y / (X + 1 + n × Y), so that the torque generation rate is reduced (or increased) at such a rate as to achieve a desired sequential cut (or sequential return). The number of fuel cut cylinders can be increased (or decreased) in accordance with the torque generation rate thus changed, so that the sequence in which the indicated torque (torque generation rate) is accurately reflected. It is possible to realize a Yarukatto and sequential return.
[0151]
Further, in the present embodiment, since the fuel injection amount calculation timing and the fuel injection timing are fixed during the execution of the sequential cut or the sequential return, it is possible to prevent the fuel cut order and the fuel return order from being disordered, Sequential cut and sequential return can be reliably executed in a predetermined order, and the cylinder that is ready for fuel cut or fuel return can be easily determined in advance. Can be specified.
[0152]
The scope of the present invention is not limited to a five-cylinder engine, and the present invention may be applied to an engine having four or less cylinders or six or more cylinders.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an entire engine control system according to an embodiment of the present invention.
FIG. 2 is a time chart for explaining a sequential cut and a sequential return.
FIG. 3 is a time chart for explaining a relationship between a fuel injection timing and an ignition timing.
4A is a time chart for explaining a relationship between a command torque used for calculating a fuel injection amount and a command torque used for calculating an ignition timing in a response mode, and FIG. 4B is a time chart for calculating a fuel injection amount in a stability mode; Chart for explaining the relationship between the command torque used for ignition and the command torque used for ignition timing calculation
FIG. 5 is a time chart for explaining a calculation method of a future rotation speed.
FIG. 6 is a time chart showing a case in which, when switching between the response mode and the stability mode, the command torque used for calculating the ignition timing is instantaneously switched between the latest command torque and the past command torque;
FIG. 7 is a time chart showing a case where the command torque used for calculating the ignition timing is gradually changed when switching between the response mode and the stability mode;
FIG. 8
(A) is a diagram showing the relationship between the torque generation rate in the sequential cut mode and the number of fuel cut cylinders, and (b) is a diagram showing the relationship between the torque generation rate in the sequential return mode and the number of fuel return cylinders.
FIG. 9
Time chart for explaining sequential cut and sequential return according to torque generation rate
FIG. 10
(A) to (c) are diagrams for explaining a countermeasure method when the calculation result of the torque generation rate change amount is an infinite decimal number.
FIG. 11
(A) is a diagram showing an example of a relationship between a fuel injection amount calculation timing and an ignition timing calculation timing, and (b) is a diagram showing a relationship between a count value of a crank counter and each stroke of each cylinder.
FIG.
Flow chart showing the processing flow of the future rotation speed calculation program
FIG. 13
Flow chart showing the flow of processing of the torque generation rate calculation program
FIG. 14
Flowchart showing the flow of processing of the indicated indicated torque calculation program
FIG.
Flow chart showing the flow of processing of the fuel cut / return determination program (part 1)
FIG.
Flow chart showing the flow of processing of the fuel cut / return determination program (part 2)
FIG.
Flow chart showing the processing flow of the fuel cut cylinder order setting program
FIG. 18 is a flowchart showing the flow of processing of a fuel return cylinder order setting program.
FIG. 19 is a flowchart showing a processing flow of a sequential fuel cut processing program;
FIG. 20 is a flowchart showing a processing flow of a sequential fuel return processing program;
FIG. 21 is a flowchart showing the flow of processing of an ignition timing retard amount calculation program;
FIG. 22 is a flowchart showing the flow of processing of a sequential cut processing program
FIG. 23 is a flowchart showing the flow of processing of a sequential return processing program
FIG. 24 is a flowchart showing the flow of processing of an all cylinder return or all cylinder cut processing program;
FIG. 25 is a flowchart showing the flow of processing of a previous value update processing program;
FIG. 26 is a diagram conceptually showing a map of an ignition timing retard amount.
FIG. 27 is a time chart showing a simulation result when the ignition timing is calculated based on the latest indicated torque.
FIG. 28 is a time chart showing a simulation result when an ignition timing is calculated based on a past instruction torque;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 15 ... Throttle valve, 20 ... Fuel injection valve, 21 ... Spark plug, 23 ... Crank angle sensor 23 (rotation speed detecting means), 24 ... Exhaust Pipe, 27 ... ECU (instruction torque calculation means, fuel injection amount calculation means, ignition timing calculation means, future rotation speed prediction means, shaft torque calculation means, instruction torque gradual change means, sequential control means).

Claims (10)

Command torque calculating means for calculating a command torque at each predetermined command torque calculation timing;
Fuel injection amount calculation means for calculating a fuel injection amount based on the command torque at each predetermined fuel injection amount calculation timing;
Ignition timing calculation means for calculating an ignition timing based on the command torque at each predetermined ignition timing calculation timing delayed from the fuel injection amount calculation timing,
The ignition timing calculation means, when calculating the ignition timing during the stability mode operation giving priority to the stability of the torque control, based on the past instruction torque calculated before the instruction torque at the ignition timing calculation timing. A torque control device for an internal combustion engine, wherein an ignition timing is calculated by using the torque control device. 2. The ignition timing calculation means according to claim 1, wherein when calculating the ignition timing during the stability mode operation, the instruction torque at the immediately preceding fuel injection amount calculation timing is used as the past instruction torque. Internal combustion engine torque control device. A future rotation speed prediction means for predicting a future rotation speed of the internal combustion engine,
3. The internal combustion engine according to claim 1, wherein the command torque calculation unit calculates the command torque based on a future rotation speed predicted by the future rotation speed prediction unit during the stability mode operation. 4. Torque control device. Rotation speed detection means for detecting the rotation speed of the internal combustion engine,
Shaft torque calculation means for calculating shaft torque based on the intake air amount of the internal combustion engine,
The said future rotation speed prediction means calculates the said future rotation speed based on the rotation speed detected by the rotation speed detection means and the shaft torque calculated by the shaft torque calculation means. Internal combustion engine torque control device. The ignition timing calculation means calculates the ignition timing based on the command torque at the ignition timing calculation timing when calculating the ignition timing during the response mode operation giving priority to the responsiveness of the torque control. Item 5. The torque control device for an internal combustion engine according to any one of Items 1 to 4. When switching between the response mode operation and the stability mode operation, the ignition timing calculation unit includes an instruction torque gradual change unit that gradually changes an instruction torque used for calculating an ignition timing. The torque control device for an internal combustion engine according to claim 5. When increasing the number of fuel cut cylinders of the internal combustion engine, a sequential cut in which fuel injection is cut in a sequence skipped by a predetermined number of cylinders with respect to the normal fuel injection order of each cylinder, and a fuel cut cylinder number of the internal combustion engine Sequential control means for executing at least one of sequential return to restart fuel injection in an order skipped by a predetermined number of cylinders with respect to the normal fuel injection order of each cylinder when decreasing,
The sequential control means changes the torque generation rate, which is the ratio of the command torque to the output torque when fuel is injected in all cylinders, by a predetermined change amount in a predetermined cycle, and changes the number of fuel cut cylinders according to the torque generation rate. The torque control device for an internal combustion engine according to any one of claims 1 to 6, wherein the sequential cut or the sequential return is performed by performing the control. When increasing the number of fuel cut cylinders of the internal combustion engine, a sequential cut in which fuel injection is cut in a sequence skipped by a predetermined number of cylinders with respect to the normal fuel injection order of each cylinder, and a fuel cut cylinder number of the internal combustion engine The internal combustion engine is provided with a sequential control means for performing at least one of a sequential return in which fuel injection is restarted in a sequence skipped by a predetermined number of cylinders with respect to a normal fuel injection sequence of each cylinder when decreasing. In the torque control device,
The sequential control means changes the torque generation rate, which is the ratio of the command torque to the output torque when fuel is injected in all cylinders, by a predetermined change amount in a predetermined cycle, and changes the number of fuel cut cylinders according to the torque generation rate. The torque control device for an internal combustion engine performs the sequential cut or the sequential return by causing the torque control to be performed. In an internal combustion engine having a total number of cylinders of Y cylinders (where Y is an integer of 3 or more), X cylinders (where X is 1) every n cycles (where n is an integer of 0 or more) with respect to the normal fuel injection order of each cylinder. When executing the sequential cut or the sequential return in the order skipped by (the above integer),
8. The method according to claim 7, wherein the predetermined cycle for changing the torque generation rate is set to a normal ignition interval of the internal combustion engine, and the predetermined change amount is set to 1 / Y / (X + 1 + n * Y). 9. The torque control device for an internal combustion engine according to claim 8. The torque control device for an internal combustion engine according to any one of claims 7 to 9, wherein a fuel injection amount calculation timing and a fuel injection timing are fixed during the execution of the sequential cut and / or the sequential return.

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