JPH05231220A - Idle rotational speed controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To make the rotational speed follow up stably a change in desired idle rotational speed according to the responsiveness of an auxiliary air control valve without being influenced by the engine operation unsteady or changed with the lapse of time. CONSTITUTION:An weighted average of desired idle rotational speed NSET is obtained to set model rotational speed Nmodel which an auxiliary air control valve 5 can follow up (S2). On the other hand, torque Tintg for error correction is set from the model rotational speed Nmodel and actual rotational speed Ne of an engine 8 (S3). Next, model output torque Tmodel needed to follow up a change in the model rotational speed Nmodel is set (S4). The error correcting torque Tintg is added to the model output torque Tmodel for correction to obtain an auxiliary air amount Q needed to follow up the model rotational speed Nmodel (S8), and control the opening of an auxiliary air control valve 5 according to the auxiliary air amount Q (S9, S10).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an internal combustion engine, and more particularly, to adjusting the responsiveness of a device for controlling the idle speed to a target speed by adjusting the amount of intake air during idle operation. Regarding technology to improve.

[0002]

2. Description of the Related Art As an idle speed control device for an internal combustion engine, an auxiliary air control valve is provided in an auxiliary air passage that bypasses a throttle valve, and the opening degree of the auxiliary air control valve is controlled during idle operation so that There is one in which the idle rotation speed is controlled by controlling the amount of auxiliary air supplied to the engine through the air passage (actual Kaihei 1-1.
79148 gazette etc.).

The auxiliary air control valve is of an electromagnetic type, and when the duty given to the auxiliary air control valve is controlled to control the opening of the auxiliary drive air control valve by controlling the pulse width of the drive pulse signal for opening the valve, the time ratio of the pulse width to the cycle is controlled. The degree of opening is controlled according to the (%). The duty ISC _ON (%) to the auxiliary air control valve is calculated, for example, by the following formula.

ISC _ON = ISC _Tw + ISC _CL where ISC _Tw is a basic control value and the engine cooling water temperature Tw
Is set by referring to the map on the ROM. I
SC _CL is a feedback correction value, which compares the engine rotation speed with the target idle rotation speed under the feedback control condition of the idle rotation speed, and based on the comparison result, brings the actual rotation speed closer to the target, for example, proportional integral control. Is set using.

Specifically, the target idle speed N _SET
Is compared with the actual engine rotation speed Ne. For example, when it is lower than the target idle rotation speed, the duty IS
C _CL is gradually increased by the integral operation amount, and the duty ISC _CL is increased and corrected according to the proportional operation amount according to the deviation between the target and the actual rotation.

[0006]

By the way, in the above idle speed control, the target idle speed N _SET is changed in accordance with the turning-on state of the auxiliary load of the air conditioner or the like, so that the auxiliary load can be divided. Is correcting the required amount of work. However, in the conventional device, the responsiveness of the auxiliary air amount control is poor because the auxiliary air amount is gradually changed over time by monitoring the actual engine rotation speed by proportional / integral control, and the target idle rotation speed is applied when the load is applied. Even if the speed is increased, the target change cannot be followed with good response, and there is a problem that a large rotation drop occurs at the initial stage of load application.

In particular, when the auxiliary air control valve uses a step motor as an actuator, the responsiveness is poorer than when a linear solenoid is used as an actuator, so the rotation drop at the initial stage of load application becomes large (Fig. 5 and FIG. 6). The above problem of the rotation drop at the time of load application can be solved to some extent by setting the proportional control operation amount in the proportional / integral control to a large extent.However, if the proportional control operation amount is increased, steady-state hunting increases. There is a problem that it will end up. Also, if the manipulated variable for proportional control can be set to an optimal value for each condition, it is possible to prevent both rotation drop when the load is turned on and hunting during steady operation. It is difficult to set the value, and a great number of matching steps are required.

In order to solve such a problem, the present applicant has
When the target idle speed changes, set the model rotation speed separately according to the response force of the auxiliary air control valve, calculate the output torque required to follow the model rotation speed, and convert this to the required auxiliary air amount. Then, a device for controlling the auxiliary air control valve so as to obtain the required amount of auxiliary air was first developed. As a result, the model rotation speed corresponding to the maximum response characteristic is accurately traced, and the occurrence of hunting is suppressed and the target change is dealt with.

However, in the above-mentioned device, the required output torque for following the model rotation speed is set using a predetermined torque calculation coefficient based on the model rotation speed.
When the engine variation and the temporal change significantly increase, the required torque may change, and it may not be possible to accurately follow the actual rotation speed with respect to the model rotation speed.

The present invention has been made in view of the above problems, and can respond to changes in the target idle rotation speed with good responsiveness and can suppress hunting during steady operation.
An object of the present invention is to provide an idle rotation speed control device that can ensure a highly accurate follow-up property without being affected by engine variations and changes over time.

[0011]

Therefore, an idle speed control device for an internal combustion engine according to the present invention includes an auxiliary air control valve in an auxiliary air passage that bypasses a throttle valve,
The amount of auxiliary air is controlled by controlling the opening of the auxiliary air control valve during idle operation to control the idle rotation speed, which is configured as shown in FIG.

In FIG. 1, the target setting means sets the target idle speed based on the engine operating conditions. Further, the model rotation setting means sets the model rotation speed which is actually the tracking target based on the target idle rotation speed set by the target setting means. Further, the model torque setting means sets the model output torque necessary for causing the actual engine rotation speed to follow the model rotation speed based on the change rate of the model rotation speed set by the model rotation setting means.

Further, the model error setting means sets a model correction torque for correcting the error in the model output torque based on the difference between the model rotation speed set by the model rotation setting means and the actual engine rotation speed. Set. Then, the model torque correction means corrects and sets the model output torque set by the model torque setting means based on the model correction torque set by the model error setting means.

Here, the required auxiliary air amount setting means sets an amount corresponding to the required auxiliary air amount based on the model output torque corrected and set by the model torque correction means and the model rotation speed, and the control means The opening degree of the auxiliary air control valve is controlled according to the amount corresponding to the required auxiliary air amount.

[0015]

With this configuration, the target idle rotation speed set based on the engine operating conditions is not set as a direct following target, but the model rotation speed that is the rotation speed actually set as the following target is set from the target idle rotation speed. To do. Then, the model output torque required to make the actual engine rotation speed follow this model rotation speed is obtained, and the auxiliary air amount is controlled so that this model output torque is actually obtained. A model correction torque corresponding to an error in the model output torque is set based on the difference from the actual engine rotation speed, and the model output torque is corrected with this model correction torque.

That is, the model output torque is set so that the actual rotation speed follows the model rotation speed, and this is converted into the required auxiliary air amount to control the opening of the auxiliary air control valve. When the model rotation speed is not accurately tracked, the error is corrected as the model correction torque so that the tracking accuracy can be maintained.

[0017]

EXAMPLES Examples of the present invention will be described below. In FIG. 2 showing the system configuration of the present embodiment, the air from the air cleaner 1 is passed through a throttle chamber 2 through a throttle valve 3 interlocking with an accelerator pedal (not shown) and an auxiliary air passage 4 bypassing the throttle valve 3. It is inhaled under the control of the mounted auxiliary air control valve 5. Then, it is mixed with the fuel injected from the fuel injection valve 7 at the branch portion of the intake manifold 6 and is sucked into the cylinder of the engine 8.

The opening of the auxiliary air control valve 5 is controlled by a control signal ISC _ON from the control unit 9, and for such control, signals from various sensors are input to the control unit 9. A crank angle sensor 10 is provided as each of the various sensors, and the engine rotation speed Ne can be calculated from the cycle T _ref of the reference signal REF output at each predetermined crank angle. A water temperature sensor 11 is provided to detect the engine cooling water temperature Tw. In addition, the idle switch 1 that is turned on when the throttle valve 3 is in the fully closed position
2. A neutral switch 13 that is turned on at the neutral position of the transmission and a vehicle speed sensor 14 for detecting the vehicle speed VSP are provided.

Here, the microcomputer in the control unit 9 controls the opening degree of the auxiliary air control valve 5 by performing arithmetic processing according to the flowchart of FIG. 3 when the feedback control condition of the idle rotation speed is satisfied. .. The feedback control condition is that the idle switch 12 is ON (throttle valve 3 is fully closed) and the neutral switch 13 is ON (neutral state), or the idle switch 12 is ON and is detected by the vehicle speed sensor 14. Vehicle speed VSP is a predetermined value (eg 8km
/ h) The condition is below.

Further, the functions of the target setting means, the model rotation setting means, the model torque setting means, the model error setting means, the model torque correction means, the necessary auxiliary air amount setting means, and the control means in this embodiment are the same as those shown in FIG. The control unit 9 is provided as software as shown in the flowchart of FIG. In the flowchart of FIG. 3, first, step 1 (denoted as S1 in the figure. The same applies hereinafter).
In the cooling water temperature Tw, A / T refers to the map storing in advance the target idle speed N _SET according to the engine operating conditions of the gear position, etc. in the target idle corresponds to the current engine operating conditions the rotational speed N _SET Ask for. The part of step 1 corresponds to the target setting means.

In the next step 2, the model rotation speed Nmodel (initial value = 0) which is the actual tracking target is set to the latest in the model rotation speed Nmodel- ₁ up to the previous time and step 1 as shown in the following equation. Target idle speed N _SET
Update and set by the weighted average value of. The step 2 corresponds to the model rotation setting means. _{Nmodel ← Nmodel -1 × r + (} 100 -r) × N SET the model rotational speed Nmodel is to vary with a predetermined response delay with respect to the target idle speed N _SET set in step 1 (FIG. 4 The weighting constant r that determines the characteristic of the response delay is set corresponding to the response of the auxiliary air control valve 5.

That is, the weighted average by the weighting constant r
The target idle speed N _SETActually follows
It is converted into a rotation speed that can be
Compared to using an actuator as aoid, the step mode
In general, the response is poor when using a
When using a promoter, the weighting constant r is
Set larger.

In step 3, the model rotation speed Nmo is set.
A model output torque Tmodel is set so as to obtain a model rotation speed Nmodel from the deviation between the engine rotation speed Ne and the model rotation speed Nmodel as a result of controlling the auxiliary air amount so as to follow del. The model correction torque Tintg (initial value = 0) for correcting the error of is calculated according to the following equation. The step 3 corresponds to the model error setting means.

Tintg ← Tintg ₋₁ + GAINE (Nmodel ₋₃ −Ne) According to the above equation, if a deviation occurs between the model rotation speed Nmodel and the actual engine rotation speed Ne, it is necessary to eliminate the deviation. The output torque is calculated as GAINE (Nmodel _-3 -Ne) using the conversion constant GAINE, the output torque is added to the model correction torque Tintg _-1 up to the previous time, and the addition result is set as a new model correction torque Tintg. To be done.

Therefore, as will be described later, the model rotation speed N
In the model output torque Tmodel calculated so that the actual engine rotation speed Ne follows the model, a calculation error occurs due to engine variation or aging, and the model rotation speed N
When the model is not followed with high accuracy, the error is corrected by the model correction torque Tintg, and the followability with respect to the target can be maintained.

Here, Nmodel- ₃ indicates the data three times before when the model rotation speed Nmodel is updated and set for each reference signal REF. That is, from the time when the opening degree of the auxiliary air control valve 5 is controlled to change the auxiliary air amount Q to the time when this actually appears as a change in the engine rotation speed Ne, a 4-cycle engine has a 1/2 cycle (360 °). Since there is a delay time of only CA), it is possible to determine whether or not the latest model rotation speed Nmodel can be followed after 360 ° CA. Therefore, the most recently detected engine rotation speed Ne is exactly the model rotation speed Nmo set before 360 ° CA.
Since we should judge whether it matches del _-3 ,
N model _-3 is compared with the latest engine rotation speed Ne to set the error amount of the output torque.

It is preferable that the model correction torque Tintg is held as data even after the ignition switch is turned off. In the next step 4,
A model output torque Tmodel, which is an output torque required to follow the change of the model rotation speed Nmodel,
The conversion constant GAINM is used for calculation according to the following equation. The step 4 corresponds to the model torque setting means.

[0028] _{Tmodel ← GAINM (Nmodel -Nmodel -1)} / T ref that is, changing the actual engine speed Ne by variation of the model rotational speed Nmodel the model output torque Tmo
It would be good to change the actual output by del.
The division of the reference signal REF by the cycle T _ref is necessary when the model rotation speed Nmodel is updated for each reference signal REF.

In the next step 5, the actual engine output torque change T _ENG is calculated according to the following equation using the conversion constant GAINM '. T _ENG ← GAINM 'The _{(Ne-Ne -1) / T} ref embodiment, since the calculated engine speed Ne based on the period T _{re f} of the reference signal REF outputted from the crank angle sensor 10, the period T _By dividing by _ref , the change rate of the rotation speed per unit time can be obtained.

In the next step 6, when there is a difference between the model rotation speed Nmodel and the actual engine rotation speed Ne under no load, the no-load output required for returning to the actual rotation speed Ne. The torque Tpump is converted into the conversion constant GAIN.
Using P, calculate according to the following formula. Tpump ← GAINP × (N model / Ne-1) In step 7, the auxiliary machine load torque T _load required for the auxiliary machine load is set to various auxiliary machine loads such as an air conditioner load and a power steering load. Presence / absence is determined and set based on information of various switches. Specifically, for example, the output torque TAC corresponding to the operation of the air conditioner compressor is set in advance, and the air conditioner load torque Tac is switched to 0 or the TAC in accordance with ON / OFF of the air conditioner switch. , Power steering load torque Tps, etc. are set in the same manner, and the accessory load torque T _load is set as the sum of these.

Then, in step 8, the auxiliary air amount Q required to make the actual engine rotation speed Ne follow the model rotation speed Nmodel is calculated according to the following equation. still,
The part of step 8 corresponds to the model torque correction means and the necessary auxiliary air amount setting means. Q ← K · Nmodel {Tmodel + (Tmodel- 3 -T ENG) + Tintg + Tpump + T load} -Q BASE above formulas are those which are set based on the basic expression that the intake air quantity Q = output torque × rotational speed Ne. Here, the coefficient K is a correction coefficient corresponding to a change in the filling efficiency,
For example, it is separately set according to the cooling water temperature Tw. Also,
Q _BASE is the amount of leaked air that is taken into the engine through another passage other than the auxiliary air control valve 5, that is, the throttle valve 3 and the like in the idle operation state.

Further, (Tmodel- ₃ -T _ENG) can also control the amount of auxiliary air according to the fixed model output torque Tmodel as to follow the change of the model rotational speed Nmodel, in fact the the model by engine variation because it may be impossible to obtain an output torque tModel, the difference between the actual torque T _ENG with respect to the torque Tmodel- ₃ requirements, is corrected as excess or deficiency by the engine variation.

Here, Tmodel- ₃ is ₃ when the model output torque Tmodel is updated and set for each reference signal REF.
Shows the previous data. That is, from the time when the opening degree of the auxiliary air control valve 5 is controlled to change the auxiliary air amount Q until this actually appears as a change in the engine output torque, a 4-cycle engine has a 1/2 cycle (360 ° CA). Since there is a delay time of), it is possible to determine whether or not the latest model output torque Tmodel is actually satisfied after 360 ° CA. Therefore, the actual torque change T detected most recently
_{To be} precise, _ENG should judge whether or not the model output Tmodel- ₃ set before 360 ° CA is satisfied.

Assuming that the engine 8 of the present embodiment is a 6-cylinder engine and the reference signal REF is output every 120 ° CA, the model output torque Tmode set before 360 ° CA.
l is the set value T at the time three times before with the reference signal REF
model- ₃ . Therefore, rather than model output torque Tmodel is calculated on the date as described above, it reads the three previous data, by comparing the the actual torque variation T _ENG This model output torque Tmodel the engine variation I am trying to get it without being affected by.

In the next step 9, in order to control the auxiliary air control valve 5 to an opening degree corresponding to the required auxiliary air amount Q obtained in step 8, a control signal corresponding to the auxiliary air amount Q required in advance. A control signal ISC corresponding to the auxiliary air amount Q currently required is referred to by referring to a map storing ISC _ON.
Search for _ON and ask. Here, it is preferable that the control signal ISC _ON or the required auxiliary air amount Q that has been set is subjected to a first-order delay correction to compensate for a control delay due to air filling in the collector portion of the intake manifold.

Then, in step 10, the set control amount ISC _ON is output to the auxiliary air control valve 5, and the auxiliary air amount set in step 6 is actually obtained via the auxiliary air control valve 5. To do so. The above steps 9 and 10 correspond to the control means. Thus, according to this embodiment, with respect to the change of the target idle speed N _SET, model rotational speed Nmode as a target that can actually follow
By setting l, the model output torque Tmo which is the output torque required in response to the change in the model rotation speed Nmodel.
The auxiliary air amount Q is controlled so that del can be obtained. Therefore, it is possible to follow the target idle rotation speed N _SET with the maximum responsiveness while suppressing the occurrence of hunting, and thereby, when the target idle rotation speed N _SET is set to be increased, a large rotation drop due to poor response occurs. It can be prevented from occurring.

Of course, it is judged whether or not the engine rotation speed Ne that actually follows the model rotation speed Nmodel is obtained, and when there is a deviation between the two due to engine variations or changes over time, such deviation is eliminated. Since the model output torque Tmodel is corrected by setting the model correction torque Tintg in the direction, high followability can be maintained without being influenced by the engine variation and the time-dependent change.

In the above embodiment, the model output torque T
In addition to the model and the model correction torque TINTG, the feedback correction amount (Tmodel- ₃ -T _ENG) or by omitting the no-load output torque Tpump and accessory load torque T _load, a final required output torque so as to set May be.

[0039]

As described above, according to the present invention, the actual engine rotation speed is set to the maximum response characteristic corresponding to the response of the auxiliary air control valve used, with respect to the change of the target idle rotation speed. Can be changed, and even if there is an error due to engine variation or change over time in the followability with respect to such a target, this can be compensated for, and a large rotation drop or hunting occurs when the target idle speed changes. It is possible to stably prevent the occurrence of.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a system schematic diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing an example of idle rotation control.

FIG. 4 is a time chart showing a relationship between a target idle rotation speed and a model rotation speed.

FIG. 5 is a time chart showing a response characteristic of idle control when an actuator having a quick response is used.

FIG. 6 is a time chart showing a response characteristic of idle control when an actuator having a slow response is used.

[Explanation of symbols]

 3 Throttle valve 4 Auxiliary air passage 5 Auxiliary air control valve 8 Engine 9 Control unit 10 Crank angle sensor 11 Water temperature sensor 12 Idle switch 13 Neutral switch 14 Vehicle speed sensor

Claims (1)

[Claims] 1. An auxiliary air control valve is provided in an auxiliary air passage that bypasses a throttle valve, and the opening amount of the auxiliary air control valve is controlled during idle operation to control the amount of auxiliary air to control the idle rotation speed. In an idle speed control device for an internal combustion engine, target setting means for setting a target idle speed based on engine operating conditions, and a model for actually following a target based on the target idle speed set by the target setting means Model rotation setting means for setting the rotation speed, and model torque for setting a model output torque necessary for causing the actual engine rotation speed to follow the model rotation speed based on the model rotation speed set by the model setting means Setting means, based on the difference between the model rotation speed set by the model rotation setting means and the actual engine rotation speed Model error setting means for setting a model correction torque for correcting the error of the model output torque, and the model output torque set by the model torque setting means to the model correction torque set by the model error setting means. Model torque correction means for making a correction setting based on the model output torque and the model output torque corrected by the model torque correction means and a necessary auxiliary air amount setting means for setting an amount corresponding to the necessary auxiliary air amount based on the model rotation speed. And control means for controlling the opening degree of the auxiliary air control valve according to the amount corresponding to the required auxiliary air amount set by the required auxiliary air amount setting means. Idle speed control device for internal combustion engine.