JPS63222963A - Acceleration slip control method for vehicle - Google Patents

Abstract

PURPOSE:To attempt improvement of control property of acceleration slip. at the beginning of acceleration slip control, by maintaining an electromagnetic value boosting and reducing brake hydraulic pressure to driving wheels in the boosted state continuously for the time longer than one cycle of a pulse state exciting current. CONSTITUTION:When a controlling device 60 detects stepping in of an accelerator pedal 18 by a sensor 20 and judges acceleration state, it reads signals from front wheel speed sensors 66 and 68 and a driving wheel speed sensor 70. And when they exceed a certain slip rate, it drives hydraulic pressure brakes 38 and 40 of driving wheels by the pressure boosting/reducing speed according to the pressure boosting/reducing by an electromagnetic directional control valve 56 and the duty ratio of a solenoid exciting current of an electromagnetic flow amount control valve 58 and executes acceleration slip control. At the beginning of this acceleration slip control, the controlling device 60 maintains the electromagnetic valve 58 in the boosted state continuously for the time longer than one cycle of a pulse state exciting current, ad after the end of the initial control, the electromagnetic valve 58 is controlled by the duty ratio. In this way, control property of acceleration slip can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the invention because the driving torque applied to the driving wheels during vehicle acceleration is excessive in relation to the coefficient of friction of the road surface.
The present invention relates to an acceleration slip control method that prevents the slip ratio of drive wheels from becoming excessively high.

Conventional Technology One type of acceleration slip control method described above is to increase or decrease the brake fluid pressure of a hydraulic brake that suppresses the rotation of the drive wheels by controlling a solenoid valve with a pulsed excitation current, thereby reducing the acceleration slip of the drive wheels. There are things that keep it at an almost appropriate value. for example,
As described in Japanese Unexamined Patent Publication No. 58-202142, an electromagnetic directional control valve and an electromagnetic flow control valve are connected in series in the middle of a liquid passage connecting a hydraulic pressure source such as an accumulator and a hydraulic brake. The hydraulic brake is selectively connected to the hydraulic pressure source and the reservoir by switching the electromagnetic directional control valve, and a pulsed excitation current is supplied to the solenoid of the electromagnetic flow control valve to periodically open and close the on-off valve. , thereby increasing or decreasing brake fluid pressure at a desired gradient. Note that the pulsed excitation current herein means a pulsed current in a narrow sense that does not include continuous excitation or demagnetization with a duty ratio of O or 100.

It is also possible to increase or decrease the brake fluid pressure by controlling a solenoid valve using a continuous excitation current (instead of using a pulsed excitation current). However, in this case, it is possible to increase or decrease the brake fluid pressure at a desired gradient. Normally, the gradient of pressure increase/decrease is too steep, resulting in a large overshoot, making it difficult to properly control brake fluid pressure. Therefore, a solenoid valve is used that can open, close, or switch in extremely short cycles. What is done is done.

Problems to be Solved by the Invention However, in this type of conventional acceleration slip control method, there is a large delay in the effectiveness of the hydraulic brake at the start of acceleration slip control, which deteriorates the acceleration slip control characteristics. was there. Hydraulic brakes are typically designed to provide brake clearance in the released state. That is, a minute gap is created between the brake rotor and the friction member, or between the friction member and the member that presses it against the brake rotor. This is done because if the friction material continues to contact the brake rotor even when the brake is released, the life of the friction member will be shortened, the brake will heat up, or energy will be lost. Furthermore, it is inevitable that some degree of elastic deformation will occur in the high-pressure rubber hoses and sealing members in the piping before a substantial braking effect is produced by the hydraulic brake, and this initial elastic deformation also causes a delay in the effectiveness of the brake. .

On the other hand, in the conventional acceleration slip control method in which the solenoid valve is controlled using a pulsed excitation current, the pulsed excitation current is supplied to the solenoid valve even at the beginning of acceleration slip control, and the solenoid valve is supplied with a pulsed excitation current from a hydraulic pressure source such as an accumulator. Since brake fluid was being supplied to the hydraulic brakes, the flow rate of brake fluid was kept low, resulting in a considerable delay in brake effectiveness.

Means for Solving the Problems In order to solve the above problems, the present invention provides an acceleration slip control method for controlling a solenoid valve with the pulsed excitation current, in which the solenoid valve is excited in a pulsed manner at the beginning of acceleration slip control. An initial control step is provided in which the pressure is continuously maintained in an increased state for a period longer than one cycle of current.

Function and Effect As described above, if the solenoid valve is kept in a pressure increasing state for a certain period of time at the beginning of acceleration slip control, the flow rate of brake fluid supplied from the hydraulic pressure source to the hydraulic brake increases, and the brake clearance is reduced. The initial elastic deformation of the high-pressure rubber hose and the like is completed in a short time, reducing the delay in brake effectiveness and improving the control characteristics of acceleration slip.

Furthermore, after the initial control stroke is completed, the solenoid valve is controlled by a pulsed excitation current, and the brake fluid pressure is increased and decreased at an appropriate gradient, reducing overshoot and stabilizing acceleration slip to keep it at an appropriate value. It can fall.

EXAMPLE Hereinafter, an acceleration slip control method which is an example of the present invention will be explained in detail with reference to the drawings showing an apparatus for carrying out the method.

The acceleration slip control device shown in Figure 1 is installed in a vehicle in which the front wheels are idle wheels and the rear wheels are drive wheels, and it reduces engine output in order to suppress the rotation of the drive wheels. This is a combination of means and a hydraulic brake device.

In the figure, 10 is an engine, and its intake manifold 1
2 has a main throttle valve 14 and an auxiliary throttle valve 1.
6 are provided in series, and the output torque of the engine 10 is adjusted by opening and closing these. The main throttle valve 14 is opened and closed by operating an accelerator pedal 18, and the depression of the accelerator pedal 18 is detected by an accelerator sensor 20. Further, the opening degree of the main throttle valve 14 is detected by a main throttle sensor 21. The sub-throttle valve 16 is opened and closed by a sub-throttle control motor 22, and its opening degree is detected by a sub-throttle sensor 24.

At the bottom of Figure 1, left and right front wheels 26.28 and left and right rear wheels 3
0.32 is shown. Rear wheels 30 and 32 are connected to the engine 10 through a power transmission mechanism (not shown) and are driven by the engine 10. Each wheel 26 to 32 is provided with a hydraulic brake 34 to 40, respectively, and these hydraulic brakes are connected to the main mask cylinder 4.
It is operated by brake fluid supplied from 2.

The main mask cylinder 42 generates equal height hydraulic pressure in two independent pressurizing chambers when the brake pedal 44 is depressed, and the hydraulic pressure generated in one pressurizing chamber is passed through a liquid passage 46. The hydraulic pressure generated in the other pressurizing chamber is transmitted to the hydraulic brakes 34, 36 of the front wheels, and the hydraulic pressure generated in the other pressurizing chamber is transmitted to the hydraulic brakes 38, 40 of the rear wheels via the liquid passage 48.

A change valve 50 is provided in the middle of the liquid passage 48, and a sub mask cylinder 52 is connected to the change valve 50 in parallel with the main mask cylinder 42. The change valve 50 transmits the higher hydraulic pressure of both the main and sub mask cylinders to the hydraulic brake 38.4'O.

The sub-mask cylinder 52 is operated by hydraulic fluid supplied from the accumulator 54 via the electromagnetic directional control valve 56 and the electromagnetic flow control valve 58 .

The electromagnetic directional switching valve 56 selectively communicates the accumulator 54 and the reservoir 61 with the sub-mask cylinder 52 under the control of the control device 60, so that brake fluid is supplied from the sub-mask cylinder 52 to the hydraulic brake 38.40. It increases or decreases the pressure. Further, the electromagnetic flow control valve 58 switches the flow rate into two stages, large and small, by changing the duty ratio of the solenoid excitation current supplied from the control device 60, and increases or decreases the pressure of the sub-mask cylinder 52 in two stages, slow and fast. At the same time, the hydraulic pressure in the sub-mask cylinder 52 can be kept constant by continuous excitation.

The hydraulic fluid pumped up by the pump 62 from the reservoir 61 is accumulated in the accumulator 54.
The hydraulic pressure of the accumulator 54 is detected by a hydraulic pressure sensor 64, and based on the detection result, the control device 60
Starting and stopping of a pump motor 65 that drives the pump 62 is controlled, so that the accumulator 54 always stores hydraulic fluid within a constant hydraulic pressure range.

The rotational speeds of the left and right front wheels 26.28 are detected by left and right front wheel speed sensors 66.68, respectively, and the rotational speeds of the left and right rear wheels 30.32 are detected by a rear wheel speed sensor 70. The rear wheel speed sensor 70 connects the engine 10 and the rear wheel 3.
The rotational speed of the rear wheels 30.32 is detected based on the rotational speed of the output shaft of the transmission provided between the rear wheels 30.32 and 30.32. These speed sensors 66, 68, 70 are connected to the control device 60.

As shown in FIG. 2, the control device 60 includes a CPU 72, an RO
M74. It is mainly a computer equipped with a RAM 76, a bus 78, etc., and this computer has an input section 8.
The respective sensors are connected via the output section 82
via the auxiliary throttle control motor 22. Electromagnetic directional valve 56. Electromagnetic flow control valve 58 and pump motor 65
is connected.

The ROM 74 stores various control programs including a brake control routine shown in the flowchart of FIG. 3, and a pressure increase/decrease mode table shown in FIG.

FIG. 5 shows an example of drive wheel slip control by the acceleration slip control device configured as described above. If the opening degree γ of the main throttle valve 14 is increased as indicated by the broken line in the center of the figure by depressing the accelerator pedal 18, the vehicle speed becomes ■.

(the average value of the speeds of the front wheels 26.28) increases as shown at the bottom of the figure, but in that case, the first reference speed ■1 and the second reference speed ■2 are respectively ■, The value is determined to be larger by a predetermined value. When the driving wheel speed, that is, the rear wheel speed ■, exceeds the first reference speed ■1, the output of the engine 10 is reduced by reducing the opening degree β of the sub-throttle valve 16, The rear wheel speed ■ is controlled to be approximately equal to the first reference speed Vl. However, when the drive wheel speed V further increases and exceeds the second reference speed V2, the brake fluid pressure Pr is transmitted to the hydraulic brake 38.40, causing the rotation of the left and right rear wheels 30.32. is suppressed. In this embodiment, the secondary throttle valve 16. The auxiliary throttle control motor 22 and the like constitute the main driving wheel rotation suppressing means, and the hydraulic brakes 38 and 40 constitute the auxiliary rotation suppressing means. By doing so, it is possible to suppress the rotation of the drive wheels while eliminating waste of energy and avoiding shortening of the life of the brake friction material as much as possible.

As is clear from FIG. 5, the sub-throttle valve 16 is activated as soon as the vehicle speed Vr exceeds the first reference speed ■1.
It is rapidly rotated in the closing direction, and after its opening degree β becomes equal to the opening degree γ of the main throttle valve 14, it is slowly rotated in the closing direction. When the rear wheel speed (V) becomes smaller than the first reference speed (V), the opening is increased, and when it becomes larger than the first reference speed (V), the opening is decreased.This engine output control Since it is not directly related to the present invention, a detailed explanation will be omitted, and the control of the hydraulic brake will be explained in detail below based on the flowchart of FIG. 3.

While the vehicle's key switch is in the ON state, the computer executes the brake control routine shown in Figure 3 for a certain period of time.
For example, it is executed every 5 m5ec. First, step S
At step 1 (hereinafter simply referred to as 31; the same applies to other steps), it is determined whether or not the accelerator sensor is ON, that is, whether or not the accelerator pedal 18 is depressed. If the accelerator pedal 18 is not depressed,
Since the vehicle is not in acceleration mode, the other steps are bypassed and one execution of the brake control routine is completed.

When the accelerator pedal 18 is depressed, the vehicle speed ■2. Rear wheel speed■7. Rear wheel acceleration α1 is calculated. The vehicle speed V is calculated as the average value of the speeds of the left and right front wheels 26.28, which are idle wheels, and the speed ■ and acceleration α2 of the rear wheels, which are driving wheels, are calculated based on the output signal of the rear wheel speed sensor 70. be done. Next, in 84, a predetermined constant value is added to the vehicle body speed ■1 calculated in S3, or a value corresponding to a constant slip rate is multiplied, and the first reference speed ■1 and the second Standard speed■2
is calculated.

Then, in S5 and S6, it is determined whether the continuous pressurization flag and the brake control flag are set, respectively. Initially, both of these determinations are No, and in S7, the rear wheel speed , is larger than the second reference speed v2. Since the result of this determination is usually NO, the execution of the program returns to the main routine (not shown), and the execution of one brake control routine ends.

While the above steps are being executed, if the rear wheel speed (2) exceeds the second reference speed (2) as shown in FIG. 5, the determination result in S7 becomes YES, and S8 is executed. Rear wheel speed■
It is determined whether the count number N of a counter for measuring the elapsed time after , exceeds the second reference speed 2 is smaller than a set value N1. Initially, the result of this determination is YES, so the continuous pressurization flag is set in S9, the count number is incremented by 1 in SIO, and the execution of one brake control routine is completed. Then, when step 85 is executed next, the determination result becomes YES, so step S6. S7 is bypassed, S8 is executed, and the same process is repeated.

As a result of this repetition, the count number N becomes the set value N.

If it becomes equal to , the determination result of S8 becomes No,
The continuous pressurization flag is reset in Sll, and 312
The counter is reset at .

That is, when the continuous pressurization flag is set in S9 a predetermined number of times, the continuous pressurization flag is reset in Sll, and this brake control routine is executed every 5 m5ec, and the counter Since the set value N1 is 4 (these values should be determined appropriately for each device), the continuous pressurization flag is 20 m5ec.

It is held in the set state for a period of time and then reset. While the continuous pressurization flag is set, the output section 82 of the control device 60 continuously supplies excitation current to the electromagnetic directional control valve 56, and the electromagnetic flow control valve 58 is kept in a demagnetized state. is the auxiliary mask cylinder 5
2 Qmsec on 2.

The communication state is maintained continuously for a period of time. Rear wheel speed V.

for 20m5ec after exceeding the second reference speed V2,
The solenoid valves 56,58 are kept in a continuously increasing pressure state, and during this initial control, hydraulic fluid is supplied at a sufficient flow rate to the auxiliary mask cylinder 52 so that the rear wheels 30,3
Brake fluid is supplied to the hydraulic brakes 38 and 40 of No. 2 at a sufficient flow rate, and the brake clearance is quickly eliminated, and the initial elastic deformation of the high-pressure rubber hose and the like is quickly terminated. Therefore, the braking effect of the hydraulic brake 38.40 appears after a very short time after the rear wheel speed ■ exceeds the second reference speed ■2, and the delay in the rise of acceleration slip control is shorter than before. , good control will be achieved.

Since the result of the determination in S5 executed after the continuous pressurization flag is reset in Sll is No, S6 is executed, but the result of this determination is YES.

The brake control flag is the rear wheel speed V, and the second reference speed V2
This is because it is set when the brake fluid pressure exceeds O, and is reset when the brake fluid pressure returns to O again after the hydraulic brakes 38 and 40 are operated. Whether or not the brake fluid pressure has returned to O can be determined by directly detecting the brake fluid pressure, but it can also be determined by comparing the sum of pressure increase times and the sum of pressure decrease times. The pressure increase time and the pressure decrease time can be detected based on control signals from the electromagnetic directional switching valve 56 and the electromagnetic flow rate control valve 58, and in this way, there is no need to provide a hydraulic sensor. However, since the pressure increase gradient within a unit pressurization time and the pressure reduction gradient within a unit depressurization time are usually not the same, the sum of the pressurization time and the sum of the decompression time should be compared with this in mind. It is necessary.

Note that the setting and resetting of the brake control flag is not necessarily essential to understanding the present invention, so a detailed explanation will be omitted.

As mentioned above, if the determination result of S6 is YES, S1
3, the pressure increase/decrease mode is determined. The pressure increase/decrease mode is determined from the pressure increase/decrease mode table in FIG. 4 based on the first and second reference speeds V, , Va, the rear wheel speed ■ calculated in S2, and the rear wheel acceleration α1. It is. For example, even after the above-described initial control is executed, the rear wheel speed V remains constant.

is equal to or higher than the second reference speed 72, the rear wheel acceleration α
1 is the negative set acceleration C; if it is smaller, it is determined to be a gradual pressure reduction; if it is 01 or more, it is determined to be a gradual pressure increase; and if it is G2 or more, it is determined to be a rapid pressure increase. Then, the electromagnetic directional control valve 56 and the electromagnetic flow control valve 58 are controlled based on the determination, so that the hydraulic brake 38.4
The zero hydraulic pressure is increased/decreased or maintained at a constant pressure. However, the rapid pressure increase here is different from the continuous pressure increase in the initial control, and is a pressure increase in which ground pressure and holding pressure are repeated in short cycles. Since the pressure holding time is shorter than in gradual pressure increase, the average pressure increase gradient is steeper, but the pressure increase gradient is gentler than in continuous pressure increase, and overshoot is smaller, resulting in acceleration slip control. can be performed well.

By performing the above brake control and the engine output control described above, the rear wheel speed v1 is controlled to a value approximately equal to the first reference speed ■1, and the rear wheel 30.3, which is the driving wheel, is
The acceleration slip of No. 2 is maintained at an appropriate value.

In this embodiment, the electromagnetic valves (the electromagnetic directional control valve 56 and the i4 magnetic flow control well 58
) is kept in a state of continuous pressure increase, but
For example, it is also possible to maintain the pressure increasing state continuously until the rear wheel acceleration α1 or the rear wheel speed (2) reaches O.

If the pressure is continuously increased for a period longer than one cycle of the pulsed excitation current, the control delay can be made smaller than before, the brake clearance disappears, and the initial elastic deformation of the high-pressure rubber hose etc. is reduced. It is particularly desirable to maintain the pressure increase continuously until the end of the process.

Furthermore, in this embodiment, the engine output reducing means constitutes the main rotation suppressing means, and the hydraulic brake main device constitutes the auxiliary rotation suppressing means, but it is possible to reverse the main and sub rotation suppressing means. That is, it is also possible to make the hydraulic brake function as the main rotation suppressing means. It is also possible to omit the engine output reduction means and configure the rotation suppression means only from the hydraulic brake.
In these cases, the effects of the present invention can be particularly effectively enjoyed.

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an apparatus for implementing an acceleration slip control method according to an embodiment of the present invention. Figure 2 shows
FIG. 2 is a block diagram showing details of the control device in FIG. 1; FIG. 3 is a flowchart showing only a portion of the control program stored in the ROM shown in FIG. 2 that is particularly relevant to the present invention. FIG. 4 is a diagram showing a pressure increase/decrease mode selection table stored in the ROM for use in executing the flowchart of FIG. 3. FIG. 5 is a graph showing an example of control by the acceleration slip control device shown in FIG. 10: Engine 14: Main throttle valve 16: Sub-throttle valve 18; Accelerator pedal 20: Accelerator sensor 22: Sub-throttle control 1111 Motor 24: Sub-throttle sensor 26: Left front wheel 28: Right front wheel 30: Left rear wheel 32 : Right rear wheel 34.36, 38.40: Hydraulic brake 50: Change valve 52: Sub-mask cylinder 54: Accumulator 56 = Electromagnetic directional switching valve 58: Electromagnetic flow control valve 60:
Control device 66: Left front wheel speed sensor 68: Right front wheel speed sensor 70: Rear wheel speed sensor

Claims (1)

[Claims] In the acceleration slip control method, the brake fluid pressure of the hydraulic brake that suppresses the rotation of the drive wheels is increased or decreased by controlling a solenoid valve with a pulsed excitation current, and the acceleration slip of the drive wheels is maintained at an approximately appropriate value. An acceleration slip control method for a vehicle, characterized in that, at the beginning of slip control, an initial control step is provided in which the solenoid valve is continuously kept in an increased pressure state for a period longer than one cycle of the pulsed excitation current.