JPH0545831B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a shift control device for an automatic transmission for a vehicle, and more particularly to a technique for easing shift shock.

BACKGROUND ART Vehicles are known that are equipped with an automatic transmission that has a plurality of gears and is automatically switched to that gear when a shift request is made. In such automatic transmissions, a shift diagram corresponding to the current gear is usually selected from a plurality of shift diagrams determined in advance, and the vehicle speed, throttle valve opening, etc. are determined from the selected shift diagram. Based on this, the shift timing and gear stage to be selected are determined. and,
The actuator of the transmission is actuated to automatically shift the transmission so that the gear position to be selected is obtained.

Generally, when automatically changing the gear stage of a transmission, first, the actuator is operated.
After the previously established gear is released, a new gear is immediately established; however, in the case of upshifting, the speed ratio obtained by the new gear causes the engine to rotate rapidly. may be lowered. This decrease in engine speed is
Changes in the rotational speed of the engine are used as driving force for the vehicle, but because these changes occur in a short period of time, an unpleasant shift shock occurs in the vehicle. In addition, this shift shock was also a factor in causing the drive wheels to slip on roads where the road surface friction coefficient was small.

On the other hand, when the transmission is to be upshifted, it has been considered to advance the ignition timing to reduce the engine output, or to lengthen the shift time to ease the shift shock.

Problems to be Solved by the Invention However, such conventional shift control devices have the following disadvantages. In other words, the method of reducing engine output by advancing the ignition timing takes time to respond to reduce engine output and cannot directly absorb changes in rotational speed, so it is difficult to adjust the speed change shock and drive wheels based on this method. Slip could not be suppressed sufficiently.
In addition, the method of relaxing the shift shock by lengthening the shift time usually involves half-engaging the friction engagement device for establishing the next gear in order to lengthen the shift time while maintaining power transmission. As a result, the durability of the frictional engagement device is impaired, and the shift response is poor due to the long shift time.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is to suppress the rotation of wheels, as shown in the claim correspondence diagram in Fig. 12. In a vehicle equipped with a braking device and an automatic transmission having a plurality of gears and automatically changing the gear when a shift request is made, a shift for changing the gear of the automatic transmission. The control device includes an engine rotation speed detection means for detecting an actual engine rotation speed, an upshift determination means for determining an upshift of the automatic transmission, and an actual engine rotation speed and after the upshift when an upshift is determined. a rotational speed difference calculating means for calculating a rotational speed difference between the rotational speed of the engine and the engine rotational speed; and a braking torque for suppressing temporary acceleration of the vehicle due to a change in the engine rotational speed during an upshift based on the rotational speed difference. and a braking control means for causing the braking device to generate the braking torque during the period in which the temporary acceleration occurs.

Effects of the Invention In this way, when the transmission is upshifted, the braking device of the vehicle is operated to suppress temporary acceleration of the vehicle caused by changes in engine rotational speed, so that the shift shock is prevented. In addition to accurately relieving the load, the slippage of the driving wheels caused by the gear shifting shock is eliminated. Furthermore, since the frictional engagement device for establishing the next gear stage is not brought into a semi-engaged state, durability of the frictional engagement device can be achieved and suitable speed change responsiveness can be obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIG. 1, hydraulic oil is supplied from a master cylinder 12 which is actuated by operating a brake pedal 10 to front wheel brakes 16, 16 provided on front wheels 14, 14 and rear wheels 18, 18 of the vehicle. It is designed to be force-fed to the rear wheel brakes 20, 20. The hydraulic pump 22 pumps the hydraulic oil in the reservoir tank 24 to the accumulator 2.
Pressure builds up within 6. The hydraulic oil accumulated in this accumulator 26 is transferred to the rear wheel brake 2 through a 3-position control valve 28, an oil passage 30, and a 2-position control valve 32.
0 and 20, the rear wheel brakes 20 and 20 are operated.

The two-position control valve 32 is connected to the master cylinder 12.
The hydraulic oil output from the rear wheel brakes 20, 20
Manual operation position and hydraulic pump 2
Hydraulic oil pumped from 2 to the rear wheel brakes 20, 2
It is positioned as an alternative to the automatic operation position for supplying to zero, and is switched and controlled by the controller 34. Moreover, the 3-position control valve 28 is
A supply position where the hydraulic oil pumped from the hydraulic pump 22 is supplied to the rear wheel brakes 20, 20, a position where the flow of the hydraulic oil pumped from the hydraulic pump 22 is cut off, and the oil passage 30 and the return oil passage 36. The rear wheel brakes 20, 20 are selectively positioned to communicate with each other and release the rear wheel brakes 20, 20, and are switched and controlled by the controller 34. The controller 34 controls the braking force of the rear wheel brakes 20, 20 by duty-controlling the three-position control valve 28.

The controller 34 includes a front wheel 14 and a rear wheel 1.
A signal representing the rotation of the accelerator pedal 40 is supplied from rotation sensors 38 and 39 provided on the front wheels 14 and rear wheels 18, respectively, to determine the speed of the vehicle, and a signal representing the amount of operation of the accelerator pedal 40 is supplied from the accelerator pedal. It is supplied from the sensor 41. Further, a signal representing the rotation of the engine 42 and a signal representing the range selected by the shift lever 43 are supplied from the engine rotation sensor 44 and the shift operation position sensor 45 to the controller 34, respectively. The controller 34 is a so-called microcomputer, and in terms of shift control of the transmission 46, it determines the vehicle speed based on signals from the rotation sensors 38 and 39, and also determines the current gear from a plurality of pre-stored shift diagrams. A shift diagram corresponding to the gear is selected, and a shift direction and shift timing are determined from the selected shift diagram based on the vehicle speed and the operation amount of the accelerator pedal 40, and a shift signal for obtaining a new gear is determined. is supplied to the transmission 46.

The transmission 46 includes an input shaft 50 connected to the engine 42 and an output shaft 52 connected to the rear wheels 18, 18 via a differential gear device (not shown), and changes the rotation speed of the engine 42. Rear wheel 18,1
It is a stepped transmission that transmits information to 8. For example, as shown in FIG. 2, the transmission 46 is provided with a plurality of planetary gear mechanisms, and a plurality of friction engagement devices for establishing a plurality of gear stages, that is, clutches C ₀ and C ₁ . , C ₂ and brakes B ₀ , B ₁ , B ₂ , and B ₃ are selectively actuated by hydraulic actuators (not shown). The plurality of frictional engagement devices are a combination of the operating states of the first solenoid valve 54 and the second solenoid valve 56 and the shift lever 43.
The transmission 46 is operated as shown by the circle in FIG. It's summery.

FIG. 4 shows a shift control circuit provided in the vehicle. The controller 34 is the CPU 58,
It is a so-called microcomputer equipped with a ROM 60 and a RAM 62, and the CPU 58 processes input signals according to a program stored in advance in the ROM 60 while utilizing the storage function of the RAM 62, and processes input signals in accordance with a program stored in advance in the ROM 60. Supplies drive signals to. Controller 34 operates, for example, according to the steps shown in FIG.

Hereinafter, the operation of the controller 34 will be explained according to the flowchart shown in FIG. First, step S1 is executed to read each input signal, and step S2 is executed to calculate the actual vehicle speed V, accelerator operation amount A _CC , and engine rotation speed N _e according to the input signals. be done. Subsequently, in step S3, a shift diagram corresponding to the actual gear stage of the transmission 46 is selected from a plurality of previously stored shift diagrams, and in step S4, the actual vehicle speed V and accelerator operation amount A are determined from the shift diagram. A shift command is determined based on _CC . This shift command specifies the gear position to be changed from the current gear position. Further, since the above-mentioned speed change diagram is a well-known diagram that is normally used in automatic transmissions, a description thereof will be omitted.

If it is determined in step S4 that a shift command has not been issued, steps S5 and S6 are skipped, but if it is determined that a shift command has been issued in step S4, the drive signal for changing gears is electromagnetic in step S5. Valve 5
4 or 56 as well as step S6.
Braking at the time of shifting is performed. For example, if the shift command is to change from the third gear to the fourth gear, in step S5, the operation of the second solenoid valve 56 is maintained and the second solenoid valve 56 is maintained in the operating state until then. At the same time, the first solenoid valve 54 is deactivated, and the step
In S6, a braking control routine during a shift shown in FIG. 6 is executed.

At step SS1 in FIG. 6, it is determined whether the shift command is an upshift or a downshift. If it is a downshift, no acceleration shock occurs during automatic shifting, so this routine is terminated, but if it is an upshift, steps SS2 and below are performed to perform braking to prevent acceleration shock during automatic shifting. is executed.
In step SS2, the current engine speed N _e
The rotation speed difference ΔN _e between the engine rotation speed N _e ′ after the gear change and the engine rotation speed N e ′ is determined. The engine rotational speed N _e ' after the gear change is calculated from the current vehicle speed V, the gear ratio of the transmission 46 at the new gear, the diameter of the rear wheel 18, and the like. In the following step SS3, the braking torque B _T is determined based on the actual rotational speed difference ΔN _e from the predetermined relationship shown in FIG. 7, for example. The relationship shown in FIG. 7 determines the optimal braking torque that should be applied to the rear wheels 18, 18 in order to prevent temporary acceleration (shift shock) of the vehicle that occurs due to changes in the rotational speed of the engine 42 during a shift. It was determined in advance that the In addition, the above braking torque B _T
corresponds to the hydraulic pressure supplied to the rear wheel brake 20 through the oil passage 30.

Next, in step SS4, the delay time is calculated based on the actual vehicle speed V from the relationship shown in FIG.
T _D is calculated. This relationship has been determined experimentally in advance so that it coincides with the time until temporary acceleration (shift shock) based on a change in engine rotational speed is started during a shift. Since the line oil pressure supplied to the actuator that operates each frictional engagement device in the hydraulic circuit in the transmission 46 is normally regulated as a function of the vehicle speed V, the delay time T _D is adjusted as a function of the vehicle speed V as described above. is determined, but even if this delay time T _D is a constant time, a certain effect can be obtained.

At step SS5, the timer T is set to the delay time T _D determined at step SS4.
In step SS6, it is determined whether or not the contents of timer T have reached zero, but since it has not reached zero initially, step SS7 is executed and 1 is subtracted from the contents of timer T. Step like this
While SS6 and SS7 are being executed, when the contents of the timer T reach zero, in other words, when the delay time T _D has elapsed since the shift command, step SS8 is executed and the 2-position control valve 32 and the 3-position control valve 28
As a result, hydraulic oil from the hydraulic pump 22 is supplied to the rear wheel brakes 20, 20 through the oil passage 30 and the two-position control valve 32, and their braking operation is started. In this case, braking is performed by duty-controlling the operating position of the three-position control valve 28 at a predetermined frequency so that the braking torque B _T determined in step SS3 is supplied to the rear wheel brakes 20, 20. Adjust the hydraulic pressure.

In the following step SS9, it is determined whether the rotational speed difference ΔN _e has reached zero. Rotational speed difference△
If N _e does not reach zero, step SS
Steps 8 to SS9 are repeatedly executed, and when step SS10 is reached, step SS10 is executed and the 2-position control valve 3
2 is operated to the automatic operating position shown in FIG.
The braking operation of the rear wheel brakes 20, 20 is ended by being positioned at the position where the operation of the rear wheel brakes 20, 20 is released.

Therefore, in this embodiment, the above step SS
2 corresponds to the rotation speed difference calculation means, and step SS
3 corresponds to the braking torque calculation means, and step SS
4 to SS10 correspond to the braking control means.

In addition, as shown in FIG. 9, in this embodiment, when the gear stage of the transmission 46 is automatically changed in response to a shift command, when the temporary acceleration of the vehicle occurs, Since appropriate braking force is applied to the rear wheels 18, 18, changes in the acceleration α of the vehicle are suppressed, and shift shocks during automatic shifting are suitably prevented, and slippage of the driving wheels caused by shift shocks is also prevented. It will be resolved. Note that point S in FIG. 9 indicates the point in time when a shift command is issued.

Furthermore, in this embodiment, since the frictional engagement device for establishing the next gear stage is not in a semi-engaged state,
The durability of the frictional engagement device can be achieved, as well as suitable speed change responsiveness.

Incidentally, FIG. 10 shows the change in vehicle acceleration when the gear stage of the transmission 46 is automatically shifted and no means for suppressing the shift shock based on the change in the rotational speed of the engine 42 is provided. Figure 11 shows engine 4 during automatic shift.
2 shows the change in vehicle acceleration when the ignition timing of No. 2 is retarded. Even in the latter case, engine 42
Since it takes time to respond to reduce the output of the engine and changes in rotational speed cannot be directly absorbed, the shift shock is not sufficiently suppressed.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be implemented in other embodiments.

For example, the relationship used in step SS3 of the above embodiment is the relationship between vehicle speed V and braking torque B _T
It may be a relationship with

In addition, in the above-mentioned embodiment, the rear wheel brake 2
0 and 20, the front wheel brakes 16, 16, or the front wheel brakes 16, 16 and the rear wheel brakes 20, 20 may be braked.

In addition, in the above-mentioned embodiment, the three-position control valve 2
The braking torque is changed by controlling the duty of the hydraulic pump 22, but by providing a hydraulic sensor that detects the output hydraulic pressure of the hydraulic pump 22, the step
The rotation of the hydraulic pump 22 may be controlled or a pressure regulating valve for regulating the output oil pressure of the hydraulic pump 22 may be operated so that the braking torque B _T determined at SS3 is obtained.

In addition, the above-mentioned Step SS2 or Step SS
It is preferable that the relationship used in step 3 is one selected from a plurality of relationships corresponding to the gear positions stored in advance in accordance with the actual gear position of the transmission 46.

Note that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a shift control device for a vehicle according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of the configuration of the transmission shown in FIG. 1. FIG. 3 is a diagram showing the relationship between the frictional engagement device and gear stages in the transmission of FIG. 1. FIG. 4 is a circuit diagram showing the configuration of the controller shown in FIG. 1. 5 and 6 are flowcharts illustrating the operation of the controller of FIG. 4. 7 and 8 are diagrams showing the relationships used in FIG. 6, respectively. 9th
The figure is a time chart illustrating the operation of each part of the apparatus shown in FIG. FIG. 10 and FIG. 11 are diagrams showing changes in acceleration during shifting in a conventional vehicle, respectively. FIG. 12 is a diagram corresponding to claims of the present invention. 18: Rear wheel (wheel), 20: Rear wheel brake (braking device), 42: Engine, 44: Engine rotation sensor (engine rotation speed detection means), 45: Shift operation position sensor (upshift determination means),
46: Transmission (automatic transmission), Step SS2: Rotational speed difference calculation means, Step SS3: Braking torque calculation means, Step SS10: Braking control means.

Claims (1)

[Claims] 1. A vehicle comprising: a braking device for suppressing rotation of wheels; and an automatic transmission having a plurality of gears and automatically changing the gears when a shift request is made. A shift control device for switching gears of the automatic transmission in a vehicle, comprising: engine rotational speed detection means for detecting an actual engine rotational speed; upshift determination means for determining an upshift of the automatic transmission; a rotational speed difference calculation means for calculating a rotational speed difference between an actual engine rotational speed and an engine rotational speed after an upshift when an upshift is determined; and a rotational speed change of the engine during an upshift based on the rotational speed difference. a braking torque calculation means for calculating a braking torque for suppressing temporary acceleration of the vehicle caused by the vehicle; and a braking control means for causing the braking device to generate the braking torque during a period in which the temporary acceleration occurs. A shift control device for an automatic transmission for a vehicle, characterized by the following.