JP2770236B2 - Valve timing control method for an internal combustion engine of a vehicle having an automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve timing control method for an internal combustion engine, and more particularly to a valve timing control method for shifting an internal combustion engine mounted on a vehicle having an automatic transmission.

(Related Art and Problems Thereof) Generally, in an internal combustion engine mounted on a vehicle equipped with an automatic transmission, the engine output torque at the time of shifting is reduced in order to reduce shift shock during shifting of the automatic transmission. It is known. Further, some methods for determining the amount of decrease in the engine output torque at the time of shifting of the automatic transmission have been conventionally proposed. However, according to these proposed methods, the operating state of the engine is detected based on various parameters, and the amount of decrease in the engine output torque is determined by complicated processing according to the detected operating state.

On the other hand, the valve timing of at least one of the intake valve and the exhaust valve is set at a low valve speed in which a relatively large engine output torque is obtained in the low rotation region in the low rotation region of the internal combustion engine, and in a high rotation region in the high rotation region. 2. Description of the Related Art There has been known an internal combustion engine capable of switching to a high-speed valve timing capable of obtaining a relatively large engine output torque so as to ensure a sufficient engine output torque over the entire rotation range of the engine (for example, Japanese Patent Publication No. Sho 49-49). -33289
issue).

(Object of the Invention) The present invention has been made in order to solve the above-mentioned problems of the prior art, and always reduces the engine output torque at the time of gear shifting without complicated processing, thereby achieving good gear shifting with little shifting shock. It is an object of the present invention to provide a valve timing control method for an internal combustion engine of a vehicle having an automatic transmission capable of obtaining characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a valve operating state of at least one of an intake valve and an exhaust valve which is suitable for a low-speed valve timing suitable for a low rotation region and a high rotation region of an internal combustion engine. A valve operating mechanism switchable between high-speed valve timing and a valve timing control method for an internal combustion engine mounted on a vehicle equipped with an automatic transmission, wherein at least one of the intake valve and the exhaust valve is in an operating state. When the automatic transmission is shifted in one of the low-speed and high-speed valve timings, the valve operating state is switched to the other of the low-speed and high-speed valve timings.

Incidentally, the switching of the valve timing referred to in this specification means
This refers to switching both or one of the valve opening period and the valve lift amount.

Embodiment An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a control device to which the control method of the present invention is applied. In FIG. 1, reference numeral 1 denotes a DOHC in-line four-cylinder engine in which each cylinder is provided with a pair of an intake valve and an exhaust valve. is there.

In the middle of the intake pipe 2 of the engine 1, a throttle body 3
And a throttle valve 3 ′ is disposed therein. Throttle valve opening (θth)
A sensor 4 is connected, and outputs an electric signal corresponding to the opening of the throttle valve 3 ′ and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

The fuel injection valve 6 is provided for each cylinder between the engine 1 and the throttle valve 3 'and slightly upstream of the intake valve (not shown) of the intake pipe 2. Each injection valve is connected to a fuel pump (not shown). And is electrically connected to ECU5
The valve opening time of fuel injection is controlled by a signal from the ECU 5.

An ignition plug 22 provided for each cylinder of the engine 1 is connected to the ECU 5 via a drive circuit 21, and the ECU 5 controls the ignition timing θig of the ignition plug 22.

An electromagnetic valve 23 for performing valve timing switching control described later is connected to the output side of the ECU 5, and the opening and closing operation of the electromagnetic valve 23 is controlled by the ECU 5.

On the other hand, an intake pipe absolute pressure (P _BA ) sensor 8 is provided immediately downstream of the throttle valve 3 ′ via a pipe 7. The absolute pressure signal converted into an electric signal by the absolute pressure sensor 8 is supplied to the ECU 5. Supplied to Further, the downstream mounted an intake air temperature (T _A) sensor 9 is supplied to the ECU5 outputs an electric signal indicative of the sensed intake air temperature T _A.

The engine water temperature (Tw) sensor 10 mounted on the main body of the engine 1 is composed of a thermistor or the like, detects the engine water temperature (cooling water temperature) Tw, outputs a corresponding temperature signal, and supplies it to the ECU 5. The engine speed (Ne) sensor 11 and the cylinder discrimination (CYL) sensor 12 are mounted around the camshaft or the crankshaft of the engine 1. Engine speed sensor 11
Outputs a pulse (hereinafter referred to as a “TDC signal pulse”) at a predetermined crank angle position every time the crankshaft of the engine 1 rotates 180 degrees, and the cylinder discriminating sensor 12 outputs a signal pulse at a predetermined crank angle position of a specific cylinder. Output
Each of these signal pulses is supplied to the ECU 5.

The three-way catalyst 14 is disposed in the exhaust pipe 13 of the engine 1 and purifies components such as HC, CO, and NOx in the exhaust gas. O ₂ sensor 15 as an exhaust gas concentration detector outputs a three-way catalyst 14 is mounted on the upstream side of the signal corresponding to the detected value by detecting the oxygen concentration in the exhaust gas in the exhaust pipe 13 ECU 5 To supply.

An output shaft of the engine 1 has an automatic transmission 19 described later.
Is connected.

The ECU 5 is further connected to a vehicle speed sensor 16, a gear position sensor 17 for detecting a shift position of the automatic transmission, and a hydraulic pressure sensor 18 for detecting a hydraulic pressure in an oil supply passage (48 in FIG. 2 (b)) of the engine 1, which will be described later. The detection signals of these sensors are
Supplied to ECU5.

The ECU 5 shapes input signal waveforms from various sensors, corrects a voltage level to a predetermined level, and converts an analog signal value to a digital signal value. The input circuit 5a has a function of a central processing unit (hereinafter referred to as a “CPU”). 5b, a storage means 5c for storing various calculation programs executed by the CPU 5b, calculation results, and the like, an output circuit 5d for supplying drive signals to the fuel injection valve 6, the drive circuit 21, and the solenoid valve 23, and the like. .

Based on the various engine parameter signals described above, the CPU 5b determines various engine operation states such as a feedback control operation area and an open loop control operation area corresponding to the oxygen concentration in the exhaust gas, and determines the next according to the engine operation state. The fuel injection time Tout of the fuel injection valve 6 synchronized with the TDC signal pulse is calculated based on the equation (1).

Tout = Ti × K ₁ + K ₂ (1) where Ti is the basic fuel amount, specifically the engine speed
This is a basic fuel injection time determined according to Ne and the intake pipe absolute pressure _PBA. The Ti map for determining the Ti value includes a low-speed valve timing (Ti _L map) and a high-speed valve timing (Ti _L map). two maps of Ti _H map) is stored in the memory means 5c.

K ₁ and K ₂ are other correction coefficients and correction variable computed according to various engine parameter signals, so that the fuel consumption characteristic according to engine operating conditions, the optimization of various properties such as the engine acceleration characteristics can be achieved Is determined to be a predetermined value.

CPU5b further absolute intake pipe and engine rotational speed Ne pressure P _BA
The ignition timing θig is determined accordingly. Similar to the Ti map, two maps for the low-speed valve timing (θig _L map) and for the high-speed valve timing (θig _H map) are stored in the storage means 5c as the θig map for determining the ignition timing. .

The CPU 5b controls the opening and closing of the solenoid valve 23 by outputting a valve timing switching instruction signal by a method shown in FIG.

The CPU 5b outputs a signal for driving the fuel injection valve 6, the drive circuit 21, and the solenoid valve 23 via the output circuit 5d based on the result calculated and determined as described above.

FIG. 2 shows an intake valve-side valve train 30 for driving the intake valve 40 of each cylinder of the engine 1. A valve train of basically the same configuration is provided on the exhaust valve side. The valve gear 30 is moved halfway from a crankshaft (not shown) of the engine 1.
And a high-speed cam 34 and a low-speed cam 32, 33 provided on the camshaft 31 corresponding to each cylinder, and are fixedly arranged in parallel with the camshaft 31. A rocker shaft 35, a first drive rocker arm 36, a second drive rocker arm 37, and a free rocker arm 38 pivotally supported by the rocker shaft 35 corresponding to each cylinder, and each rocker arm 36, 37, 38 corresponding to each cylinder.
And a connection switching mechanism 39 provided between them.

In FIG. 2 (b), a connection switching mechanism 39 includes a first switching pin 41 capable of connecting the first drive rocker arm 36 and the free rocker arm 38, and a second switching pin 41 capable of connecting the free rocker arm 38 and the second drive rocker arm 37. A second switching pin 42, a regulating pin 43 for regulating movement of the first and second switching pins 41 and 42,
A return spring 44 for biasing each of the pins 41 to 43 toward the connection release side.

The first drive rocker arm 36 has a bottomed first guide hole 45 opened to the free rocker arm 38 side in parallel with the rocker shaft 35, and a first switching pin 41 slides in the first guide hole 45. The hydraulic chamber 46 is movably fitted between the one end of the first switching pin 41 and the closed end of the first guide hole 45. Further, a passage 47 communicating with the hydraulic chamber 46 is formed in the first drive rocker arm 36, and an oil supply passage 48 is formed in the rocker shaft 35.
The oil supply passage 48 is always in communication with the hydraulic chamber 46 via the passage 47 irrespective of the swinging state of the first drive rocker arm 36.

A guide hole 49 corresponding to the first guide hole 45 is formed in the free rocker arm 38 in parallel with the rocker shaft 35 between both side surfaces, and one end of the first switch pin 41 is abutted on the other end. The second switching pin 42 is slidably fitted in the guide hole 49.

A second guide hole 50 having a bottom corresponding to the guide hole 49 is formed in the second drive rocker arm 37 so as to open toward the free rocker arm 38 and is formed in parallel with the rocker shaft 35.
The disc-shaped regulating pin 43 that contacts the other end of the switching pin 42 is the second
It is slidably fitted in the guide hole 50. In addition, a guide cylinder 51 is fitted into the closed end of the second guide hole 50, and a shaft portion 52 slidably fitted in the guide cylinder 51 is coaxially and integrally protruded from the regulating pin 42. You. The return spring 44 is inserted between the guide cylinder 51 and the regulating pin 43, and the pins 41, 42, and 43 are urged toward the hydraulic chamber 46 by the return spring 44.

In the connection switching mechanism 39, the first switching pin 41 is fitted in the guide hole 49 and the second switching pin 42 is fitted in the second guide hole 50 by increasing the hydraulic pressure in the hydraulic chamber 46,
Each rocker arm 36, 38, 37 is connected. When the oil pressure in the hydraulic chamber 46 decreases, the contact surface of the first switching pin 41 with the second switching pin 42 returns to a position corresponding to between the first drive rocker arm 36 and the free rocker arm 38 by the spring force of the return spring 44, Since the contact surface of the second switching pin 42 with the regulating pin 43 returns to a position corresponding to between the free rocker arm 38 and the second drive rocker arm 37, the connected state of each rocker arm 36, 38, 37 is released.

The oil supply passage 48 in the rocker shutter 35 is connected to the oil pump 25 via the switching valve 24, and the switching operation of the switching valve 24 causes the oil pressure in the oil supply passage 48, and thus the connection switching mechanism.
The hydraulic pressure in the 39 hydraulic chamber 46 is switched between high and low. The switching valve 24 is connected to the solenoid valve 23, and the switching operation of the switching valve 24 is controlled by the ECU 5 via the solenoid valve 23.

Intake side valve train of engine 1 configured as described above
30 works as follows. Note that the exhaust-side valve gear operates in the same manner.

When a valve opening command signal is output from the ECU 5 to the solenoid valve 23, the solenoid valve 23 opens, the switching valve 24 opens, and the oil pressure in the oil supply passage 48 increases. As a result, the connection switching mechanism 39
Is activated and each rocker arm 36, 38, 37 is connected,
The rocker arms 36, 38, and 37 are integrally operated by the high-speed cam 34, and the pair of intake valves 40 are opened and closed at a high-speed valve timing in which the valve opening period and the lift amount are relatively large.

On the other hand, when a valve closing command signal is output from the ECU 5 to the solenoid valve 23, the solenoid valve 23 and the switching valve 24 close and the oil supply passage 48
Oil pressure drops. As a result, the connection switching mechanism 39 operates in the opposite direction to the above, the connection state of each rocker arm 36, 38, 37 is released, and the corresponding rocker arms 36, 37 are operated by the low speed cams 32, 33, respectively, and a pair of The intake valve 40 operates at a low valve timing in which the valve opening period and the lift amount are relatively small.

FIG. 3 shows the configuration of the automatic transmission shown in FIG. 1. The output of the engine 1 is transmitted from a crankshaft 71 of the vehicle through a torque converter T as a fluid transmission, an auxiliary transmission M, and a differential Df in that order. To the left and right drive wheels W, W 'to drive them.

The torque converter T includes a pump wheel 72 connected to a crankshaft 71, a turbine wheel 73 connected to an input shaft 75 of the auxiliary transmission M, and a stator shaft 74a rotatably supported on the input shaft 75. It is constituted by a stator wheel 74 connected via a one-way clutch 78.

A first speed gear train G ₁ , a third speed gear train G ₃ , a fourth speed gear train G ₄ , and a reverse gear train Gr are arranged in parallel between the mutually parallel input / output shafts 75 and 76 of the transmission M. Is provided. Further, an idle shaft 77 is provided in parallel with the output shaft 76, and a second speed gear train is provided on the idle shaft 77.
G ₂ is provided.

The first speed gear train G ₁ is connected to the input shaft via a first speed clutch G _1.
A drive gear 87 connected to the gear 75, and an output shaft meshed with the gear 87;
76 through the one-way clutch C ₀ consists of driven gear 88. connectable. The second speed gear train G ₂ includes a driven gear 89 connectable to the idle shaft 77 via the second speed clutch C ₂ , and a drive gear 90 fixed to the output shaft 76 and meshing with the gear 89. The third speed gear train G ₃ includes a drive gear 91 fixed to the input shaft 75, and a driven gear 92 connected to the output shaft 76 via a third speed clutch C ₃ and meshable with the gear 91. The fourth speed gear train G ₄
It is a fourth gear via a clutch C ₄ and the driving gear 93 which is connected to the input shaft 75, driven gear 94. which is coupled to an output shaft 76 via the switching clutch Cs is meshed with the gear 93. Further reverse gear train Gr includes a fourth speed drive gear 93 and the driving gear 95 provided integrally with the gear train G _4, and the driven gear 97 which is coupled via a switching clutch Cs to the output shaft 76 gears The idle gear 96 meshes with the gears 95 and 97. The switching clutch Cs
Is provided in the middle of the driven gears 94 and 97, and shifts the selector sleeve S of the clutch Cs to the left forward position or the right reverse position in the drawing, so that the driven gears 94 and 97 are connected to the output shaft 76. Can be selectively connected. The one-way clutch C ₀ only the transmission drive torque from the engine 1, the torque in the opposite direction is not transmitted.

And Thus, when the selector sleeve S is held in the forward position as illustrated, by connecting only the first speed clutch C _1, the first speed gear train driving gear 87 is connected to the input shaft 75
G ₁ is established, the output shaft from the input shaft 75 via the gear train G ₁
The torque is transmitted to 76. Then stay connected to the first speed clutch C _1, by connecting the second speed clutch C _2, the drive gear
90 second speed gear train G ₂ is established is connected to the input shaft 75, the torque is transmitted to the output shaft 76 from the input shaft 75 via the gear train G _2. At this time, the first speed clutch C ₁ is also engaged, but now the second speed does not become the first speed by the action of the one-way clutch C _0, which is the third speed, even when the fourth speed The same is true. By connecting the third speed clutch C ₃ to release the second speed clutch C _2, the third-speed gear train G ₃ is established driven gear 92 is connected to the output shaft 76, and the third speed clutch C ₃ if connected through a fourth speed clutch C ₄ to release the drive gear 93 and the fourth speed gear train G ₄ is connected is established to the input shaft 75. Further moved rightwards selector sleeve S of the switching clutch Cs, by connecting only the fourth speed clutch C _4, drive gear 95 is connected to the input shaft 75, reverse gear driven gear 97 is connected to the output shaft 76 A train Gr is established, and reverse torque is transmitted from the input shaft 75 to the output shaft 76 via the gear train Gr.

The torque transmitted to the output shaft 76 is transmitted from the output gear 98 provided on an end portion of the shaft 76 to the large diameter gear D _G of the differential Df.

FIG. 4 is a graph showing the characteristics of the engine output torque according to the valve timing control method according to the present invention.
T ”), high-speed valve timing (hereinafter“ high-speed V / T ”)
2) shows the relationship between the engine speed and the engine output torque T when the engine speed is controlled.

The engine speed Ne ₁ is the lower limit speed at which the engine output obtained at the low valve timing always exceeds the engine output obtained at the high valve timing. The engine speed Ne ₂ is the engine output obtained at the high valve timing. Is the upper limit engine speed that always exceeds the engine output obtained by Switching of the valve timing is carried out in a region between the rotational speed Ne ₁ and Ne _2, with a hysteresis in this embodiment the switching from the low-speed valve timing to the high-speed valve timing and switching of the opposite, Ne
₁ for example 4800rpm / 4600rpm, Ne ₂ for example 5900rpm / 5700r
Set to pm.

In FIG. 4, when the engine rotational speed Ne is in a low rotational speed region where the engine rotational speed Ne is equal to or less than the predetermined engine rotational speed Ne ₁ (Ne <Ne ₁ ), the output torque by the low speed V / T is higher than the high speed V It is larger than the output torque by / T. On the other hand, when the engine speed Ne is the predetermined engine speed Ne ₂ or more high speed region (Ne> Ne _2), larger than the output torque direction of the output torque due to high-speed V / T is due to the low speed V / T. This is because the volumetric efficiency of the engine is improved in the low speed region (Ne <Ne ₁ ) with the low speed V / T, and in the high speed region (Ne> Ne ₂ ) with the high speed V / T. .

Therefore, in order to obtain the best output torque characteristics, the valve timing is usually set to the low speed V / T in the low rotation region (Ne <Ne ₁ ) and to the high speed V / T in the high rotation region (Ne> Ne ₂ ). Control.

Next, the magnitude of the shift impact generated during shifting of the automatic transmission is smaller when the output torque of the engine is smaller. This is because, when the output torque of the engine is small, the absolute value of the hydraulic pressure for controlling the engagement and disengagement of the clutch of the automatic transmission, that is, the hydraulic pressure from the oil pump driven by the engine is reduced, and the absolute value of the hydraulic pressure from the start of engagement is completely reduced. This is because the change per hour of the engaging friction force until the engagement can be reduced, and as a result, the shift impact can be reduced.

Therefore, according to the method of the present invention, the engine output is reduced in order to reduce the impact during shifting, that is, as shown in FIG. When shifting in the range, the valve timing is switched to the high-speed V / T. On the other hand, when shifting in the high-speed range controlled by the high-speed V / T, the valve timing is switched to the low-speed V / T to change the valve timing. Reduce engine output torque.

Next, the valve timing control according to the present invention will be described in detail with reference to FIGS.

First, FIG. 5 is a flowchart of a program for detecting whether or not the automatic transmission used for the valve timing switching control at the time of shifting is shifting. This program is TD
This is executed in synchronism with this every time a C signal pulse is generated.

First, in steps 501 and 502, the flag F _VTSHTH or F
It is determined whether or not _VTSHTL is set to 0.
The flag F _VTSHTH is set to 1 when shifting is in progress in the low engine speed range, and is set to 0 when shifting is not in progress.
The flag F _VTSHTL is set to 1 when the gear is being _shifted in the high speed region of the engine, and is set to 0 when the gear is not being _shifted . If the gear is not being shifted, that is, if both the flags are 0 as a result of the determinations in steps 501 and 502, it is determined in step 503 whether or not a shift command has been issued. If the answer is negative (No), the flag F is determined in steps 504 and 505. _VTSHTH and F _VTSHTL are each reset to 0. If the answer to the step 503 is affirmative (Yes), that is, if it is determined that the shift is commanded, the step 50 is executed.
In 6 it is determined whether the valve timing is low speed V / T,
If the answer is negative (No), that is, if the engine is operating in the high speed region and the valve timing is high speed V / T, the flag _FVTSHTL is set to 1 in step 507. Next, at step 508, the engine speed change ΔNe is monitored.At step 509, it is determined whether or not the change ΔNe is smaller than a predetermined engine speed change guard value Δη, that is, whether or not the shift is completed. Determine. If the answer to step 509 is affirmative (Yes), the flag F _VTSHTL is reset to 0 (step 510).

If the answer to step 509 is negative (No), that is, if it is determined that the shift has not been completed, the process returns to step 501. In this case, since the flag F _{VTSHTH in} step 501 is set to 0 and the flag F _{VTSHTL in} step 502 is set to 1, the steps 508 and 509 are executed until the shift is completed.

On the other hand, if the answer to step 506 is affirmative (Yes), that is, if the engine is operating in the low rotation speed region and the valve timing is low speed V / T, the engine speed Ne is determined in step 511.
_Is higher than the predetermined engine speed N _VTSHT , and if the answer is negative (No), the _routine jumps to step 512 and the flag F _VTSHTH is reset to 0 (step 51).
2). That is, when a shift is commanded while the engine is in the low rotation region and is operating at the low speed V / T, if the valve timing is switched to the high speed V / T by the program of FIG. Since the torque decreases, engine stall may occur at a predetermined engine speed N _VTSHT or lower. Therefore, when the engine is operated at a rotation speed equal to or lower than the predetermined engine rotation speed N _VTSHT , the valve timing is not switched.

If the answer to step 511 is affirmative (Yes), that is, if it is determined that the engine speed Ne is larger than the predetermined engine speed N _VTSHT and engine stall does not occur even if the valve timing is switched to high-speed V / T. , Step 513
Sets the flag F _VTSHTH to 1. Next, similarly to steps 508 and 509, steps 514 and 515 are executed. If the answer to step 515 is affirmative (Yes), that is, if it is determined that the shift has been completed, the flag F _VTSHTH is reset to 0 (step 512). If the answer to step 515 is negative (No), that is, if it is determined that the shift has not been completed, the process returns to step 501. In this case, since the flag F _{VTSHTH of} step 501 is set to 1, the steps 514 and 515 are executed. Executed until termination.

FIG. 6 is a flowchart of a program for executing the valve timing switching control according to the present invention. This program is also executed in synchronism with the generation of each TDC signal pulse.

First, in step 601, it is determined whether or not signals are normally input from the various sensors to the ECU 5 or whether or not an abnormality has already occurred in another control system, that is, whether or not fail-safe should be performed.

Specifically, an intake pipe absolute pressure (P _BA ) sensor 8, a cylinder discrimination (CYL) sensor 12, an engine speed (TDC) sensor 11,
Abnormal output from the engine water temperature sensor 10 and vehicle speed sensor 16, abnormal ignition timing control signal output and abnormal fuel injection control output, abnormal current flowing through the valve timing control solenoid valve 23, valve timing control solenoid valve 23 Abnormal change such that a normal oil pressure change in an outlet port (not shown) in the switching valve 24 and communicating with the oil supply passage 48 cannot be confirmed by the oil pressure switch in the oil pressure sensor 18 even after a lapse of a predetermined time according to the opening and closing of the valve Is detected and it is determined that the engine is in the operating state to be fail-safe. Note that a cylinder discrimination (CYL) sensor and T
When one of the DC sensors has an abnormality, the other output is used in place of the one output.

When the answer to step 601 is affirmative (Yes), that is, when fail-safe should be performed, the process proceeds to step 636 described below, and negative (No)
If so, the process proceeds to step 602 and subsequent steps.

Steps 602 to 609 are steps for determining whether or not the engine output can be reduced. Step 602
Then, it is determined whether or not the engine is being started based on the engine speed Ne or the like. Step 603 is the remaining time t of the delay timer.
s _T is the step of determining whether it is 0, ts _T
Is set to a predetermined time (for example, 5 seconds) during the start (step 604), and the timing operation is started after the start. 605 is a step for determining whether or not the engine water temperature Tw is lower than a set temperature Tw ₁ (for example, 60 ° C.), that is, whether or not warm-up has been completed; 606 is a set vehicle speed V _{1 at which the} vehicle speed V is extremely low (with hysteresis) , For example, 8 km / 5 km), 607 is a step of determining whether the engine-equipped vehicle is a manual vehicle (MT), 608 is an automatic vehicle (A
The step of the shift lever is determined whether or not it is the parking (P) range or the neutral (N) range if the T), 609 is a step Ne, it is determined whether or not the lower limit value Ne ₁ or more, Fail safe (Step 601
Is affirmative (Yes)), during start-up (answer in step 602 is affirmative (Yes)), after the start, before the delay time set time ts _T elapses (answer in step 603 is negative (No)), during warm-up ( If the answer to step 605 is affirmative (Yes), the vehicle is stopped or running slowly (step
If the answer of 606 is affirmative (Yes), and if it is in the P, N range (the answer of step 608 is affirmative (Yes)), the solenoid valve 23 is closed and the valve timing is set to the low speed valve timing as described later. Hold.

If Ne <Ne ₁ (the answer in step 609 is negative (N
o)), At step 610, it is determined whether the flag F _VTSHTH is 1 or 0. The flag F _VTSHTH is set to 1 in step 513 of FIG.
2 is set to 0 each. When the flag F _VTSHTH is 1, that is, when the engine is shifting, the engine speed is _{equal to} or higher than the predetermined speed N _{VTSHT and} equal to or lower than Ne ₁ (in the low speed region and the high
When the switching to the high-speed V / T is permitted because the engine stall does not occur even if the switching to the high-speed V / T is performed, step 620 is executed to open the solenoid valve 23 to switch the valve timing to the high-speed V / T. . When the flag F _VTSHTH is 0, that is, when the shift is not in progress, or when the engine speed is _lower than the predetermined speed N _VTSHT during the shift, the switching to the high-speed V / T is prohibited. The valve 23 is closed to maintain the valve timing at the low-speed valve timing.

When it is determined in step 609 that Ne ≧ Ne ₁ holds, in step 611, a Ti _L map and a Ti _H map are searched, and the Ti value of the Ti _L map according to the current Ne and P _BA (hereinafter, referred to as Ti)
Ti _L ) and the Ti value of the Ti _H map (hereinafter referred to as Ti _H ) are obtained, and then in step 612, a T _VT corresponding to Ne is read from a T _VT table set according to the AT car and the MT car. , Step
At 613, this T _VT is compared with T _{OUT of the} previous loop, and T _OUT ≧
It is determined whether or not T _VT is satisfied, that is, whether or not the _engine is in a high load state in which the air-fuel mixture is enriched. The answer is negative (No), ie T
_{If OUT} < _TVT , the routine proceeds to step 614, where Ne
There discriminates whether the upper limit value Ne ₂ or more. Step 6
When the answer to 14 is negative (No), that is, when Ne <Ne ₂ holds, the routine proceeds to step 615, where Ti _L obtained in step 611 is determined.
And comparing the Ti _H. As a result, when Ti _L > Ti _H is satisfied, it is determined whether or not the timer value t _VTOFF of the delay timer set in step 618 described later is zero (step 61).
6) If this answer is affirmative (Yes), the flag F
It is determined whether _VTSHTH is 1 or 0.

When the flag F _VTSHTH is 1 as in the step 610,
That is, when the engine is in the low rotation region and shifting, the above-described step 620 is executed, the electromagnetic valve 23 is opened, and the valve timing is switched to the high-speed V / T. When the shift is completed, the flag _FVTSHTL is set to 0 in step 512 of FIG. 5, so step 621 is executed, the solenoid valve 23 is closed, the valve timing is switched to the low speed V / T, and the normal valve Return to the timing. Steps 613, 614, 61
When any of T _OUT ≧ T _VT , Ne ≧ Ne ₂ , and Ti _L ≦ Ti _H is satisfied in each step of 5, the timer value of the solenoid valve opening delay timer is set to t _VTOFF (for example, 3 seconds). And start (step 618), and flag F in step 619
It is determined whether _VTSHTL is 1 or 0. The flag F
_VTSHTL is set to 1 at step 507 in the program of FIG.
Alternatively, they are set to 0 in steps 505 and 510, respectively. When the flag F _VTSHTL is 1, that is, when the engine is in the high rotation region and shifting, step 621 is executed, the solenoid valve 23 is closed, and the valve timing is switched to the low speed V / T. When the shift is completed, the flag F is set at step 510 in FIG.
_{Since VTSHTL} is set to 0, step 620 is executed, and the solenoid valve 23 is opened to speed up the valve timing.
Switch to V / T to return to normal valve timing.

When a valve closing command is issued in step 621, it is determined in step 622 whether or not the hydraulic switch in the hydraulic sensor 18 has been turned on, that is, whether or not the hydraulic pressure in the oil supply passage 48 has become low. When the answer is affirmative (Yes), that is, when the hydraulic switch is turned on, it is determined in step 623 whether or not the remaining time t _LVT of the low-speed valve timing switching delay timer has become zero. The answer to step 623 is affirmative (Yes), that is, t _LVT
When = 0, the remaining time t _HVT of the high-speed valve timing switching delay timer is set to a set time (for example, 0.1 second) in step 624, and then the Ti map and ignition used in the fuel injection control routine are set in step 625. A process of selecting a Ti _L map and a low-speed valve timing ignition timing map (θig _L map) is performed as a timing map, and in a subsequent step 626, it is determined whether or not the flag F _VTSHTL is 1 or 0. performs processing for the Reburimitta value N _HF c the value N _HF c ₁ for the low-speed valve timing in step 627 when.

The step 626 is performed when the engine is in the high rotation region and is operating at the high speed V / T, and once the speed is switched to the low speed V / T in steps 619 and 621 of the present program. _This is to prevent _HF c from being changed to the low-speed V / T rev limiter value N _HF c ₁ , that is, to maintain the rev limiter value at the high-speed V / T rev limiter value N _HF c ₂ . Therefore, once the low speed V /
If the flag F _VTSHTL of step 626 is set to 1 to switch to T, step 632 is executed and N _HF c
_Is maintained at the value N _HF c ₂ for high-speed V / T.

On the other hand, when the valve opening command is issued in step 620, it is determined in step 628 whether or not the hydraulic switch in the hydraulic sensor 18 has been turned off, that is, whether or not the hydraulic pressure in the oil supply passage 48 has become high. When the answer is affirmative (Yes), that is, when the hydraulic switch is turned off, it is determined in step 629 whether or not the remaining time t _HVT of the high-speed valve timing switching delay timer has become zero. When the answer to step 629 is affirmative (Yes), that is, when t _HVT = 0, at step 630, the remaining time t _LVT of the low-speed valve timing switching delay timer is set to a set time (for example, 0.2 seconds). fast N _HF c in performs a process of selecting a respective Ti _H map and the high-speed valve timing for ignition timing map (? ig _H map) as Ti map and ignition timing map for use in injection control routine of the fuel, in the following step 632 A process for setting the value N _HF c ₂ for valve timing is performed.

By the way, both switching delay timers t _HVT , t _LVT described above
Is set in accordance with the response delay time from when the solenoid valve 23 is opened and closed to when the switching valve 24 is switched, the oil pressure in the oil supply passage 48 changes, and the switching operation of the connection switching mechanism 39 of all cylinders is completed. When the solenoid valve 23 is switched from open to closed, until the hydraulic switch in the hydraulic sensor 18 is turned on,
The program proceeds in the order of 622 → 629 → 630 → 631 → 632, and after turning on, proceeds in the order of 622 → 623 → 631 → 632 until the connection switching mechanism 39 of all cylinders switches to the low speed valve timing side, and the solenoid valve Even when a valve closing command is issued due to a failure of the switching valve 24, the switching valve 24 does not switch to the closing side, and even when the hydraulic switch in the hydraulic sensor 18 does not turn on for a long time, 622 → The process proceeds in the order of 629 → 630 → 631 → 632, and as long as the connection switching mechanism 39 of all the cylinders does not switch to the low-speed valve timing side, the fuel injection control is maintained at the high-speed valve timing. When switching the solenoid valve 23 from the closed state to the open state, in the same manner as described above, unless the connection switching mechanism 39 of all the cylinders is switched to the high-speed valve timing side, the fuel injection control is adapted to the low-speed valve timing. Will be maintained.

On the other hand, the answer in step 602 is affirmative (Yes), or the answer in step 603 is negative (No), or
When the answer to 06 is affirmative (Yes), that is, during the start and before the elapse of the set time after the start, during the warm-up, during the stop, or during the slow running, the process proceeds to step 633 to issue a valve closing command of the electromagnetic valve 23,
From step 633, proceed in the order of 624 → 625 → 626 → 627. In the case of the N and P ranges in step 608, step 6
Proceed to 34 to determine whether to select the Ti _H maps the last loop, and the flag F _VTSHTH in step 610 is 0
Also at step 634, the process proceeds to step 634. When the answer to step 634 is affirmative (Yes), that is, when selecting the last loop Ti _H map, the timer value t _VTOFF of the solenoid valve opening delay timer to zero (step 635), the step 621 proceeds, when the answer to step 634 is negative (No), i.e. the previous Ti _H
When the map is not used, in other words, when the connection switching mechanisms 39 of all the cylinders are not switched to the high-speed valve timing side, 633 → 624 → 625 → 626 →
Proceeding in the order of 627, fuel injection control suitable for low-speed valve timing is performed irrespective of the hydraulic switch in the hydraulic sensor 18. This is a countermeasure when the hydraulic switch in the hydraulic sensor 18 is kept off due to disconnection or the like.

Incidentally, N _HF c ₁ described above is set higher than Ne _2, the valve timing before the normally Ne rises N _HF c ₁ is switched to the high-speed valve timing, N _HF value of c N _HF c
_Since it is switched to ₂ , the fuel cut at _NHF c ₁ is not performed. In contrast, steps 602 to 608 to step 633
In the operating state proceeding, since Ne by racing and the like are held in the low-speed valve timing even exceed the Ne _2, the fuel cut at the N _HF c ₁ is performed. Also, even if the low-speed valve timing is switched to the high-speed valve timing, the fuel cut at N _HF c ₁ is performed until t _HVT becomes 0, that is, until the coupling mechanism 39 is actually switched to the high-speed valve timing. .

If the answer to the above step 601 is affirmative (Yes), that is, if the fail-safe operation is being performed, a command to close the solenoid valve 23 is issued (step 636), and fail-safe processing is performed (step 63).
7) Go to step 627.

(Effects of the Invention) As described in detail above, the present invention provides a valve operating state of at least one of an intake valve and an exhaust valve for a low-speed valve timing suitable for a low-speed region and a high-speed valve suitable for a high-speed region of an internal combustion engine. It has a valve actuation mechanism that can be switched with timing,
In a valve timing control method for an internal combustion engine mounted on a vehicle equipped with an automatic transmission, the automatic transmission is controlled when at least one of the intake valve and the exhaust valve is in one of the low-speed and high-speed valve timings. When the speed of the automatic transmission is changed, the valve operating state is switched to the other of the low speed and the high speed valve timing, so that the output torque of the engine is controlled to be lower at the time of shifting of the automatic transmission, and the clutch engagement of the automatic transmission is performed. Can be reduced by a simple method without requiring complicated processing unlike the conventional method.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an engine and a control device to which a valve timing control method of the present invention is applied, FIG. 2 is a diagram showing a valve train of an engine and a control system thereof, and FIG. FIG. 4 is a diagram showing the relationship between the engine speed Ne and the torque by the valve timing control according to the present invention, and FIG. 5 is used for valve timing switching control during gear shifting according to the present invention. FIG. 6 is a flowchart of a program for detecting whether or not the automatic transmission is shifting, and FIG. 6 is a flowchart of a valve timing switching control routine. 1 ... internal combustion engine, 5 ... electronic control unit (ECU), 6 ... fuel injection valve, 11 ... engine speed sensor, 19 ... automatic transmission, 23 ... solenoid valve, 24 ... switching valve, 30 …… valve drive, 40 …… intake or exhaust valve, 48 ……
Refueling channel.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 13/00 301 F01L 1/34 F02D 13/02

Claims (1)

(57) [Claims] 1. A valve operating mechanism capable of switching at least one of an intake valve and an exhaust valve between a low-speed valve timing suitable for a low-speed region and a high-speed valve timing suitable for a high-speed region of an internal combustion engine. In the valve timing control method for an internal combustion engine mounted on a vehicle having an automatic transmission, the automatic operation may be performed when at least one of the intake valve and the exhaust valve is in one of the low-speed and high-speed valve timings. A valve timing control method for an internal combustion engine, wherein the valve operating state is switched to the other of the low-speed and high-speed valve timings when the transmission is shifted.