JPH0759904B2 - 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. When the automatic transmission shifts up from, for example, the first speed to the second speed or from the second speed to the third speed, this device temporarily outputs the output shaft torque of the automatic transmission after receiving the shift-up signal. In order to suppress this torque increase, the fuel supply amount is reduced and the engine output is reduced at the time of the above-mentioned shift up.

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 sudden change in throttle opening during acceleration, etc. The transmission gear mechanism actually starts switching operation, 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. At the time of downshifting, the engine speed and the turbine speed of the automatic transmission increase due to the change in the gear ratio. The greater the degree of increase in the rotational speed, the more rapid the change in torque, and the higher the peak torque accordingly. (See Figure 3). Conventionally, sufficiently effective measures have not been taken against such problems.

(Object of the Invention) In view of the above circumstances, the present invention is caused by the peak torque as described above when an automatic downshift is automatically performed in response to a change in throttle opening during acceleration. (EN) Provided is an engine control device for a vehicle with an automatic transmission capable of reducing shift shock and adjusting the output shaft torque to an extent corresponding to the magnitude of peak torque.

(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, Rotation speed detection means 7 for detecting the engine speed or turbine speed of the automatic transmission, engine output adjusting means 3 for adjusting the output of the engine 2, and engine speed or automatic transmission when the automatic transmission 1 is downshifted. The rotation speed increase degree detecting means 4 for detecting the increase degree of the turbine rotation speed, and the engine output is reduced when the rotation speed detected by the rotation speed detecting means 7 at the time of downshifting due to acceleration becomes a predetermined value or more, And an engine output control means 5 for outputting to the engine output adjusting means 3 a control signal for increasing the engine output decrease amount as the rotation speed increase degree increases. It is a thing.

That is, the automatic transmission 1 is controlled by the control unit 6 that stores the shift pattern, and when downshifting due to acceleration,
Torque fluctuation occurs due to the switching operation of the transmission gear mechanism in the automatic transmission 1 in response to the downshift signal from the control unit 6, and the engine speed and the turbine speed also rise. By reducing the engine output by an amount according to the degree of increase in number, the peak torque is appropriately suppressed. Also, during downshifting due to acceleration, control to reduce engine output is
This is performed when the engine speed or the turbine speed detected by the speed detecting means 7 becomes a predetermined value or more, so that the timing for reducing the engine output in order to suppress the peak torque is accurately and surely. Detected by.

(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
Is composed of a torque converter, a speed change gear mechanism, and a hydraulic circuit for driving the same, and a plurality of solenoid valves 11 incorporated in the hydraulic circuit are controlled by a control unit 10 so that speed change is performed. . Although the speed change gear mechanism of the automatic transmission 1 is generally known, detailed description and illustration thereof are omitted.
It is composed of various gear elements combined with a predetermined planetary gear structure and various friction elements such as brakes, clutches, and one-way clutches that control the movements of these elements, so that the gear ratio changes according to the operation of the friction elements. Has become. 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 that detects the turbine speed of the torque converter. It is installed 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. 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, 26
Is an O ₂ sensor provided in the exhaust passage 16, and signals from these are also input to the control unit 10.

Further, the control unit 10 is supplied with a signal (1, 2, D range signal) 27 for designating the range of the automatic transmission 1, a signal 28 from an ignition switch, and the like. In addition to this, various signals necessary for controlling the automatic transmission 1 and the engine 2 may be input to the control unit 10.

Then, the control unit 10 stores a shift pattern in which the shift position of the automatic transmission 1 is set in advance according to the vehicle speed and the throttle opening, and the solenoid valve 11 outputs a signal for controlling the automatic transmission 1 based on this shift pattern. On the other hand, the signal for controlling the fuel system, the ignition system, etc. of the engine 2 is output to the fuel injection valve 17, the fuel pump 18, the igniter 21, etc. In particular, 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 according to the turbine speed as described later. Therefore, the control unit 10
Includes the control unit 6, the rotation speed increase degree detection means 4 and the engine output control means 5 shown in the configuration explanatory view of FIG.
Further, the fuel system constitutes the engine output adjusting means 3 during downshifting.

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 the time chart of FIG. 3. The calculated value of the shift speed based on the shift pattern changes to the low speed side in accordance with the change in the throttle opening due to acceleration, etc. When the downshift signal is output to the solenoid valve 11 at t ₀ , the speed change gear mechanism switches and operates with some delay accordingly, and accordingly, the output shaft torque of the automatic transmission changes as shown by line A. As the turbine speed fluctuates, line B
It changes like. 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 rises excessively and peak torque (line A ₁ ) is generated before the torque value after downshifting 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, the engine output is reduced when the turbine speed becomes equal to or higher than the reference speed (predetermined value) Nb. Specifically, the turbine speed is set to be somewhat lower than the expected convergent speed Nc. When the number of revolutions reaches Nb t ₁
This is detected, and from this time t ₁ , the engine output is reduced by correcting the fuel injection amount in the decreasing direction. Then, the fuel correction amount Vh in this case is set according to the increase degree ΔN of the turbine rotation speed, and as shown in FIG. 4, the fuel correction amount Vh is increased as the increase degree ΔN increases. In addition to this, it is desirable to change the correction amount Vh depending on the shift speed, the hydraulic pressure, the throttle opening degree, etc. at the time of downshift related to the torque fluctuation. Further, the fuel correction end time is 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 the downshift due to acceleration (line B '), even if the correction is ended at a point when the turbine rotation speed becomes stable after considering such a case. Good.

This control is explained by the flow chart in FIG. 5. This flow chart shows that the ignition switch is ON.
The initial setting is performed in step S ₁ , and thereafter, the processes in step S ₂ and subsequent steps are repeated.

In step S ₂ , information from various sensors and switches is read, and in step S ₃ , the basic injection amount Vb of fuel is calculated according to the intake air amount, the engine 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, when the shift down due to acceleration, whether or not during shifting up the speed change operation is completed from the start in response to a shift-down signal, on the basis of the turbine speed such as detection examining . When the determination result is NO, the basic injection amount Vb to a final injection amount V at step S _7, and outputs a control signal corresponding to the final injection amount V at step S ₈ the fuel injection valve to (injector) 17 From step S ₂
Return to.

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 expected convergent speed Nc is multiplied by a constant coefficient K to set the reference speed Nb (see FIG. 3).
Together, calculates the turbine speed increase of ΔN at step S _12, after setting the correction amount Vh as in the fourth diagram of above in accordance with the increase of ΔN at step S _13, step S ₁₄
Move on to. Further, when the correction amount already determined (determination result is YES in step S _9), the processing proceeds to step S ₁₄ without passing through step S ₁₀ to S _13.

Step S ₁₄ in the turbine speed is checked whether reaches the reference rotational speed Nb, until it reaches the reference rotational speed Nb does not perform the correction by moving to step S _7. Reference speed
After reaching 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 basic injection amount Vb
A value obtained by subtracting the correction amount Vh from the above is set as the final injection amount V, and then the process returns to step S ₂ via step S ₈ . After reaching the expected convergent rotation speed Nc, the correction is completed by moving to step S ₇ .

By the control as described above, the peak torque generated near the switching operation end timing of the transmission gear mechanism becomes small during the downshift due to acceleration. That is, as described above, the output shaft torque of the automatic transmission rises rapidly from the time when the operation progresses to some extent in response to the switching operation of the speed change gear mechanism at the time of downshifting. A peak torque is generated at the peak torque, and the peak torque increases as the degree of increase in turbine speed increases. On the other hand, in the above control, when the turbine speed becomes equal to or higher than the predetermined value, the fuel injection amount is reduced by an amount corresponding to the increase rate, so that the rapid torque corresponding to the turbine speed increase degree is increased. The rise is moderately suppressed. Therefore, as shown by the line A ₂ in FIG. 3, the output shaft torque smoothly shifts to the torque value after downshifting, the peak torque becomes smaller than in the conventional case (line A ₁ ), and the shock feeling is reduced. The Rukoto.

In the above embodiment, the engine output is corrected in accordance with the detection of the turbine speed during the downshift, but the engine speed also increases in the same manner as the turbine speed during the downshift. The engine speed may be detected instead of the speed. Further, the correction control of the engine output during the downshift may be performed by the ignition timing instead of the fuel injection amount,
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, according to the present invention, when the automatic transmission shifts down due to acceleration, when the engine speed or the turbine speed of the automatic transmission becomes equal to or higher than a predetermined value, the correction is performed in the direction of decreasing the engine output. Since the output torque of the automatic transmission is controlled, the peak torque generated when the output shaft torque of the automatic transmission shifts to the torque value after the downshift through the torque increasing process can be suppressed. In particular, considering that the degree of increase in the rotational speed is related to the magnitude of the peak torque, according to the degree of increase in the rotational speed, the engine output reduction degree is increased as the rotational speed increase degree increases. By appropriately suppressing the peak torque, it is possible to effectively reduce the shift shock.

[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 flowchart 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 ... Rotation speed increase detecting 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 gearshifting pattern according to a running state of the vehicle, and a rotation speed detection for detecting an engine rotation speed or a turbine rotation speed of the automatic transmission. Means, an engine output adjusting means for adjusting the output of the engine, a rotational speed increase degree detecting means for detecting an increase rate of the engine speed or the turbine speed of the automatic transmission during a downshift of the automatic transmission, and a shift due to acceleration. At the time of down, the engine output is reduced when the number of revolutions detected by the number of revolutions detecting means becomes a predetermined value or more, and the engine output is reduced by increasing the degree of increase in the number of revolutions. An engine control device for a vehicle with an automatic transmission, comprising: an engine output control means for outputting to an adjusting means.