JPH0623545B2 - Engine control device in vehicle with automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine control device in a vehicle with an automatic transmission, and particularly to control during downshift.

(Prior Art) Generally, an automatic transmission automatically shifts gears based on a shift pattern preset according to a running state of a vehicle, that is, a shift position corresponding to a vehicle speed and an engine load (throttle opening). A preset shift pattern is stored in the control unit, and the shift is controlled according to this shift pattern.

In a vehicle equipped with such an automatic transmission,
A fuel supply device as disclosed in, for example, Japanese Patent Laid-Open No. 56-96129 is known as a device for controlling an engine in connection with an automatic transmission. This device
When the automatic transmission shifts up, for example, from the first speed to the second speed, or from the second speed to the third speed, the output shaft torque of the automatic transmission temporarily increases after the shift-up signal is received. Focusing on the fact that there is a time, in order to suppress the torque increase, the fuel supply amount is reduced and the engine output is reduced at the time of the upshift.

By the way, in the above-mentioned conventional technology, only the torque fluctuation at the time of shift-up is focused, but there is a shift shock at the time of shift-down. There is a peak torque that occurs near the end of the operation. That is, in an automatic transmission, a downshift is automatically performed in response to a change in throttle opening during acceleration or a decrease in vehicle speed during deceleration. The transmission gear mechanism actually starts switching operation with some operation delay, and the output shaft torque of the automatic transmission fluctuates according to this switching operation. In this case, since the torque value after the downshift is higher than the torque value before the downshift, the output shaft torque increases relatively rapidly as the switching operation proceeds, but near the end time of the switching operation. By the time the output shaft torque converges to the torque value after downshifting, there is a tendency for it to rise excessively to generate peak torque, and a shock feeling is given if this peak torque is high. For such a problem, it is possible to reduce the engine output in synchronism with the shift signal. However, if this is done, for example, the acceleration performance in the early stage of the downshift is impeded during the downshift during acceleration, and it is sufficiently effective. It is not a countermeasure. Further, the height of the peak torque changes depending on the degree of increase (how quickly the output shaft torque increases) when the switching operation of the transmission gear mechanism progresses and the output shaft torque increases rapidly. The control of the peak torque cannot be appropriately performed by the control of reducing the output by a certain amount.

(Object of the Invention) In view of the above circumstances, the present invention reduces the shift shock caused by the peak torque by reducing the engine output when the automatic transmission is downshifted, and particularly, during the period of engine output reduction and the engine. The present invention provides an engine control device for a vehicle with an automatic transmission, which can appropriately adjust the amount of output reduction and effectively reduce shift shock.

(Structure of the Invention) As shown in the structure explanatory view of FIG. 1, the present invention relates to a vehicle including an automatic transmission 1 that shifts gears based on a shift pattern preset according to the running state of the vehicle, An engine output adjusting means 3 for adjusting the output of the engine 2 and a detecting means 4 for detecting that a shift operation is in progress after the shift gear mechanism actually starts switching when the automatic transmission 1 is downshifted. In accordance with this detection, the engine output control means 5 for outputting to the engine output adjusting means 3 a control signal for reducing the engine output while the switching operation is in progress.
A turbine rotation speed detection means 7 for detecting the turbine rotation speed of the torque converter in the automatic transmission 1; and a turbine rotation speed increase degree during downshift based on the detection by the turbine rotation speed detection means 7, Control signal setting means 8 is provided for increasing the engine output decrease amount due to the control signal of the rising engine output control means 5 as the turbine rotation speed increase degree increases.

In this configuration, the switching operation in progress means a period during which the output shaft torque of the automatic transmission is in the process of increasing due to the progress of the switching operation of the transmission gear mechanism, and for example, the turbine rotation speed becomes equal to a predetermined reference rotation speed. It is the period from the time when the shift is reached to the time when the shift is completed. Further, the turbine rotation speed increase degree means the turbine rotation speed increase amount per fixed time.

With this configuration, the following effects can be obtained.

That is, the automatic transmission 1 is controlled by the control unit 6 which stores the shift pattern, and at the time of downshifting, the shift gear mechanism in the automatic transmission 1 has a certain operation delay according to the downshift signal from the control unit 6. Switching operation is performed. In this case, the engine output is controlled to decrease within the period during which the torque is relatively rapidly increasing during the switching operation, and the engine output increases as the turbine rotation speed increase degree increases. The amount of decrease is increased. As a result, the above-mentioned peak torque is appropriately suppressed.

(Embodiment) FIG. 2 shows the entire structure of an automatic transmission 1, an engine 2, and a control system for them.
A control unit (ECU) 10 comprehensively controls the automatic transmission 1 and the engine 2. The automatic transmission 1 includes a torque converter, a speed change gear mechanism, and a hydraulic circuit that drives the speed change gear mechanism. A plurality of solenoid pulps 11 incorporated in the hydraulic circuit are provided in the control unit 10.
The shift is performed by being controlled by. Since the speed change gear mechanism of the automatic transmission 1 is generally known, detailed description and illustration thereof will be omitted, but various gear elements combined with a predetermined planetary gear structure, and a brake for controlling the movements thereof, It is composed of various friction elements such as a clutch and a one-way clutch, and the gear ratio is changed according to the operation of the friction elements.
The automatic transmission 1 includes a vehicle speed sensor 12 that detects the vehicle speed from the rotation of its output shaft, an inhibitor switch 13 that detects neutral and parking states, and a turbine speed sensor 14 (which detects the turbine speed of the torque converter). (Equivalent to the turbine speed detection means 7 in FIG. 1)
Are attached, and signals from these are input to the control unit 10.

On the other hand, for the engine 2, an intake passage 15 and an exhaust passage 16, a fuel system including a fuel injection valve 17, a fuel pump 18, and the like, and an ignition system including an ignition plug 19, a distributor 20, an igniter 21, and the like are provided. A throttle valve 22 is arranged in the intake passage 15. Reference numeral 23 is an air flow meter for detecting the intake air amount, 24 is a crank angle sensor attached to the distributor 20, 25 is a throttle opening sensor for detecting the opening of the throttle valve 22, and 26 is an O ₂ provided in the exhaust passage 16. These are sensors, and signals from these are also input to the control unit 10.

Further, the control unit 10 includes a signal (1, 2, D range signal) 27 for designating the range of the automatic transmission 1,
A signal 28 or the like from the ignition switch is input. Besides this, control of the automatic transmission 1 and engine 2
The control unit 10 sends various signals necessary for controlling
You can input it in.

Then, the control unit 10 uses the automatic transmission 1 in advance.
A shift pattern in which the shift position is set according to the vehicle speed and the throttle opening is stored, and a signal for controlling the automatic transmission 1 is output to the solenoid valve 11 based on this shift pattern. A signal for controlling the ignition system and the like is output to the fuel injection valve 17, the fuel pump 18, the igniter 21, and the like. Particularly, at the time of downshifting, the engine output is controlled by outputting a control signal for correcting the fuel injection amount to the fuel injection valve 17 as described later. Therefore, the control unit 10 includes the control unit 6, the detection unit 4, the engine output control unit 5 and the control signal setting unit 8 shown in the configuration diagram of FIG. The output adjusting means 3 is configured.

The control of the automatic transmission 1 and the control of the engine 2 may be performed by separate control units, but in this case, communication may be performed between the control units.

An outline of the control operation by the control unit 10 will be described with reference to a time chart of FIG. 3. According to a change in throttle opening due to acceleration and a change in vehicle speed due to deceleration,
When the calculated value of the shift speed based on the shift pattern changes to the low speed side and the downshift signal is output to the solenoid valve 11 at that time T ₀ , the shift gear mechanism switches accordingly with some delay. Works, and with this,
The output shaft torque of the automatic transmission fluctuates as shown by line A, and the turbine speed changes as shown by line B. That is, the output shaft torque is temporarily reduced by the resistance of the rotating body when the transmission gear mechanism actually starts switching, and then rapidly increases as the switching operation progresses, but near the end timing of the switching operation. Then, there is a tendency that the torque temporarily increases excessively and a peak torque (line A ₁ ) is generated before the torque value after the downshift converges. Further, the turbine rotational speed rises according to the change in the gear ratio from the time when the transmission gear mechanism starts switching, and becomes stable when the switching operation ends. The more the turbine speed changes rapidly, the more rapidly the torque changes, and the greater the peak torque.

Therefore, based on the detection of the change in turbine rotational speed, for example, when the turbine rotational speed reaches a reference rotational speed Nb that is set to be somewhat lower than the expected convergent rotational speed Nc, this is detected to actually switch the transmission gear mechanism. The engine output is reduced by detecting the timing t ₁ in the torque increasing process after the start and correcting the fuel injection amount in the decreasing direction from this timing t ₁ . Then, the fuel correction amount Vh in this case is set in accordance with the degree of increase in turbine rotation speed (the amount of increase per unit time) ΔN, and as shown in FIG. 4, the fuel correction amount Vh increases as the degree of increase ΔN increases. Is increased, that is, the reduction amount of the fuel injection amount is increased to increase the engine output reduction amount. In addition to this, it is desirable to change the correction amount Vh depending on the gear position, the hydraulic pressure, the throttle opening degree, and the like at the time of downshift related to the torque fluctuation. Further, the end time of the fuel correction is time t ₂ when the turbine speed reaches the expected convergent speed Nc. Alternatively, since the turbine rotation speed rises above the expected convergent rotation speed Nc during shift down due to acceleration (line B ′), even if the correction is terminated at a point in time after the turbine rotation speed has risen and has become stable in consideration of such a case. Good.

This control will be described with reference to the flow chart of FIG.
Start with N, perform initial setting in step S ₁ ,
After that, the processing from step S ₂ onward is repeated.

In step S ₂ sensors, reads information from the switch, in step S _3, the calculation of the basic injection amount Vb of the fuel according to the intake air amount and the engine rotational speed and the like. Subsequently, in step S _4, performs the computation of the gear position based on the shift pattern in accordance with the vehicle speed and the throttle opening degree, outputs a control signal corresponding thereto to the solenoid valve 11 (Step S _5). Next, in step S _6, whether it is during the shift to the shift operation is completed from the start in response to the down-shifting signal is examined on the basis of the turbine speed detection or the like. If the determination result is NO, step S ₇
In step S, the basic injection amount Vb is set as the final injection amount V.
_{At 8} , the control signal corresponding to the final injection amount V is output to the fuel injection valve (injector) 17, and then the process returns to step S ₂ .

When the determination in step S ₆ is YES, the correction amount of the fuel injection amount is checked whether the determined or not in step S _9.
Then, if the correction amount undetermined, as a process of determining the correction timing and the correction amount determined expected convergence speed Nc on the basis of the turbine speed increases previous value Na and the gear ratio in step S _10, step At S ₁₁ , the above predicted convergent rotation speed Nc
Is multiplied by a constant coefficient K to set the reference rotation speed Nb (see FIG. 3), the turbine rotation speed increase degree ΔN is calculated in step S ₁₂ , and the increase degree ΔN is calculated in step S _13.
The correction amount Vh is set in accordance with the above, and then the process proceeds to step S ₁₄ . In addition, the correction amount has been determined (step S ₉
If the determination result of YES), the flow proceeds to step S ₁₄ without passing through step S ₁₀ to S _13.

In step S ₁₄ turbine speed increases a reference rotational speed Nb
Checks whether reached, until it reaches the reference rotational speed Nb does not perform the correction by moving to step S _7. After reaching the reference rotational speed Nb determines whether reached predicted convergence speed Nc in step S _15. Until the reaching expected convergence speed Nc shifts to step S _16,
The value obtained by subtracting the correction amount Vh from the basic injection amount Vb to a final injection amount V, then step S through step S ₈
Return to ₂ . After reaching the expected convergence speed Nc, step S
_The correction is completed by moving to ₇ .

By the control as described above, the peak torque generated near the end timing of the switching operation of the transmission gear mechanism is reduced during the downshift. That is, as described above, the output shaft torque of the automatic transmission increases rapidly from the time when the operation progresses to some extent according to the switching operation of the speed change gear mechanism during downshifting as described above. To
The fuel injection amount is corrected in the decreasing direction by the correction amount Vh according to the turbine rotation speed increase degree ΔN, and the engine output decreases,
This suppresses a rapid torque increase at the end of the switching operation. Therefore, as shown by line A ₂ in FIG. 3, the output shaft torque smoothly shifts to the torque value after downshifting, the peak torque becomes smaller than that of the conventional one (line A ₁ ), and the shock feeling is reduced. Will be done.

In the above embodiment, the correction control of the engine output at the time of downshifting is performed by the fuel injection amount, but instead of this, the ignition timing may be controlled. In this case,
The ignition timing may be corrected to the retard side at the above-mentioned predetermined timing. In addition to this, control of the engine output at the time of downshifting can be performed by the exhaust gas recirculation amount or the like.

(Effects of the Invention) As described above, the present invention reduces the engine output during the period in which the switching operation of the transmission gear mechanism progresses and the output shaft torque increases during the downshift of the automatic transmission. Since the correction control is performed, it is possible to control the peak torque that occurs when the torque value after the shift down shifts to the torque value through the torque increasing process. In particular, according to the degree of increase in turbine speed during downshifting, the larger this value, the larger the amount of decrease in engine output. Therefore, the shift shock caused by the peak torque can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of the present invention, FIG. 2 is a schematic diagram of the entire structure showing an embodiment of the present invention, FIG. 3 is a time chart showing an outline of control operation at the time of downshifting, and FIG. 4 is downshifting. Fig. 5 is a diagram showing the relationship between the degree of increase in turbine speed and the correction amount of the fuel injection amount, and Fig. 5 is a flowchart showing a specific example of control. 1 ... Automatic transmission, 2 ... Engine, 3 ... Engine output adjusting means, 4 ... Detection means, 5 ... Engine output control means, 10 ... Control unit.

Claims (1)

[Claims] 1. A vehicle equipped with an automatic transmission that shifts gears based on a preset shift pattern according to the running state of the vehicle, and engine output adjusting means for adjusting the output of the engine, and shift of the automatic transmission. Detecting means for detecting that the switching operation is in progress after the transmission gear mechanism actually starts switching when down, and the control symbol for reducing the engine output during the switching operation according to the detection. An engine output control means for outputting to the engine output adjusting means, a turbine rotation speed detection means for detecting a turbine rotation speed of a torque converter in an automatic transmission, and a turbine at the time of downshift based on the detection by the turbine rotation speed detection means. The degree of increase in the number of revolutions of the turbine is calculated, and the larger the degree of increase in the number of revolutions of the turbine is, The engine control apparatus in a vehicle with automatic transmission, characterized in that a control signal setting means for increasing the engine output reduction amount.