JP2514011B2 - Vehicle brake control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake control device used for an automobile or the like, and for wheel lock prevention control during braking and acceleration slip prevention of drive wheels during starting. It is devised so that the wheel acceleration slip control can be effectively performed with a small number of constituent members.

(Prior Art) For preventing wheel lock during braking, for controlling wheel lock prevention to increase / decrease the pressure reduction supplied to the wheel cylinder according to the rotational state of the wheel with respect to a threshold value, and for preventing drive wheel slip during start. The wheel acceleration slip control, which controls the driving force by adjusting the hydraulic pressure of the wheel cylinder according to the slip state with respect to the threshold value, is conventionally configured as an individual device.

The reason for this is that the drive torque generated on the adhesive surface of the drive wheel is less than about 1/3 of the brake torque, which is a small value. This is because the rising rate must be sufficiently smaller than that used for wheel lock prevention control.

However, there is a disadvantage that the equipment cost is increased and the equipment space is widened by separately providing the control device for each control in this way.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems such as high equipment cost due to the necessity of separate devices for the wheel lock prevention control and the wheel acceleration slip control, respectively. By effectively combining common parts that can be applied to the control of No. 1, the number of parts is reduced, and a low cost brake control device is proposed.

(Means for Solving Problems) The configuration of the present invention for solving the above problems connects the master cylinder 2 that generates the brake fluid pressure, the wheel cylinders Cd, Cf of the brake device, and the master cylinder 2. A normally open gate valve GV provided in the liquid passage a and closed during wheel lock prevention control or wheel acceleration slip control during braking, and a liquid passage 3 between the gate valve GV and the wheel cylinder 2. Booster cylinder device connected
Liquid transfer chamber that is slidable inside the pressure increasing cylinder device TC with the TC and the pressure reducing cylinder device RC and is connected to the liquid passage 3 at both ends respectively.
A pressure increasing piston TP, which is divided into T ₁ and a rear chamber T _2, and a pressure reducing chamber R ₁ and a back chamber R _2, which are slidable in the pressure reducing cylinder device RC and are connected to the liquid passage at both ends. The decompression piston RP that is divided, the accumulator 6 that stores hydraulic pressure, and the wheel lock prevention control or the wheel acceleration slip control that is provided between the accumulator 6 and the rear chamber T ₂ and the back chamber R ₂ Between the normally closed first valve device BV for selectively introducing the hydraulic pressure of the accumulator 6 into the rear chamber T ₂ and the back chamber R ₂ , and between the reservoir 5 and the rear chamber T ₂ and the back chamber R _2. A vehicle brake control device comprising a certain normally closed second valve device DV.

(Operation) During normal brake operation by the brake pedal 1, the back chamber R ₂ of the pressure reducing piston RP and the rear chamber T ₂ of the pressure increasing piston TP are set to the normally closed first valve device BV and the second valve device DV. Since both are closed, the pistons RP and TP on both sides do not operate.

In wheel lock prevention control and wheel acceleration slip control,
Since the gate valve GV is closed, the first valve device BV and the second valve device DV are controlled to open and close according to the command of the control unit 11 in response to the running state of the wheel with respect to the deceleration state threshold value or the stop threshold value. The accumulator hydraulic pressure supplied to the chamber R ₂ and the rear chamber T ₂ is adjusted.

That is, in the wheel lock prevention control, the brake fluid pressure acts on the fluid delivery chamber TS, but the pressure increasing piston TP is inoperative, and the pressure reducing piston RP is braked by the operation of the first valve device BV and the second valve device DV. It moves to the right by hydraulic pressure. As a result, the brake fluid of the wheel cylinders Cf, Cd is introduced into the decompression chamber R ₁ , and the brake fluid pressure is reduced to a braking force that does not cause wheel lock. In wheel acceleration slip control, the pressure reducing piston RP remains biased to the delivery chamber R ₁ side and remains stopped, and the pressure increasing piston TP applies a driving force control hydraulic pressure proportional to the hydraulic pressure in the rear chamber T ₂ to the driving wheel Fr. It is supplied to the wheel cylinder Cd, and the braking force generated by the wheel cylinder Cd causes the vehicle to start with a driving force in a state of small slip.

In the lock prevention control, the opening and closing of the first valve device BV and the second valve device is controlled by the control unit 11, and quick brake release and braking action in the wheel lock prevention control can be performed.

In the wheel acceleration slip control, the booster piston TP rear chamber T ₂
The control unit 11 is set so as to change the hydraulic pressure of the accumulator that acts on the vehicle, and the braking force in the wheel acceleration slip control is finely adjusted to prevent the occurrence of slip at the time of starting and obtain the maximum driving force. Since the built-in valve BV and the delay valve DV are used in common for both of the above controls, the control device has a reduced number of parts and is inexpensive and compact.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a hydraulic circuit diagram, and FIG. 2 shows a control block diagram thereof.

The brake fluid pressure corresponding to the depression force of the brake pedal 1
The brake fluid pressure generated in the master cylinder 2 in the fluid chamber A of the master cylinder 2 is supplied to, for example, the A-system braking device of the front left drive wheel Fr and the right rear driven wheel Rr via the fluid path a, The brake fluid pressure in the fluid chamber B is supplied to the B-system brake devices (not shown) on the front right drive wheel and the left rear driven wheel via the fluid passage b and the gate valve. Here, only the A system will be representatively described. The brake fluid pressure that has passed through the normally open type gate valve GV is supplied from the fluid passage 3 to the wheel cylinder Cd of the brake device for the drive wheel Fr on the left front, and at the same time as the normally open type cut valve KV and known proportioning. It is supplied to the wheel cylinder Cf of the brake device for the right rear driven wheel Rr via the valve PCV.

A pressure reducing chamber R ₁ of the pressure reducing cylinder device RC and a liquid feeding chamber T ₁ of the pressure increasing cylinder TC are both connected to the liquid passage 3. The decompression piston RP of the decompression cylinder device RC is a spring installed in the back chamber R _2.
It is biased toward the decompression chamber R ₁ by RS. The pressure-increasing piston TP of the pressure-increasing cylinder device TC is biased toward the rear chamber T ₂ by the spring TS provided in the liquid feeding chamber T ₁ . The pump 4 driven by the motor M always stores the liquid pumped up from the reservoir 5 at a constant reduced pressure in the accumulator 6. This accumulator pressure reduction is supplied to the back chamber R ₂ and the rear chamber T ₂ when the normally closed second valve device DV is opened and the first valve device BV is opened. The rear chamber T ₂ is a one-way valve 15 from which only the discharge towards the liquid path 13 is free.
Is connected to the liquid path 13 via. A throttle 14 is provided in parallel with the one-way valve 15. The back chamber R ₂ and the rear chamber T ₂ are connected to the reservoir 5 via the liquid inlet / outlet passage 13 and the normally closed second valve device DV.

The gate valve GV, the cut valve KV, the first valve device BV, and the second valve device DV are, as described below, in the normal brake control wheel lock prevention control and the wheel acceleration slip control, respectively, by the depression operation of the brake pedal 1. It is controlled to open and close.

An example of the control circuit is shown as a block diagram in FIG. 2, but the rotation speeds of the drive wheel Fr and the driven wheel Rr are detected by the rotation sensors S ₁ and S ₂ . The deceleration rate of the wheel in the limit state where the wheel lock does not occur during braking is set, for example, as a deceleration state threshold value by the deceleration state threshold value setting means 7 in consideration of the deceleration state of the vehicle. _The deceleration rate that appears during braking is calculated by the deceleration state detection means 8 based on the rate of change in the detected values of ₁ and S ₂ . The slip detection means 9 calculates the slip ratio of the driving wheel Fr at the time of starting with reference to the output of the rotation sensor S ₂ of the driven wheel Rr, and the slip ratio at which the adhesion coefficient between the tire and the road surface becomes maximum is slip threshold. Set by the value setting means 10.

The deceleration state detection means 8, the slip detection means 9, the deceleration state threshold value setting means 7, the slip threshold value setting means
10 can be configured by, for example, a microcomputer, and the control unit 11, which is also configured by a microcomputer, determines that the calculated deceleration rate and slip rate have a predetermined relationship with the threshold value. Thus, in the wheel lock prevention control or the driving force control, each valve of the gate valve GV, the cut valve KV, the first valve device BV, and the second valve device DV is controlled.

That is, during normal braking by the brake pedal 1, the gate valve GV, the cut valve KV, the first valve device BV, and the second valve device DV are all controlled to be non-energized as shown in FIG. The brake fluid pressure generated in the master cylinder 2 is
The brake fluid pressure is supplied to the wheel cylinder Cd of the drive wheel Fr, and the brake fluid pressure thereof is reduced by the proportioning valve PCV and supplied to the wheel cylinder Cf of the driven wheel Rr.

The pressure reducing piston RP is stopped on the pressure reducing chamber R ₁ side by the spring piston RS, and the pressure increasing piston TP is stopped on the rear chamber T ₂ side by the brake fluid pressure and the spring TS.

The hydraulic pressure pressurized by the pump 4 is accumulated in the accumulator 6, but since the first valve device BV is closed, this hydraulic pressure does not act on both pistons RP and TP.

When the wheels are about to be locked during the brake operation by the brake pedal 1, the wheel lock prevention control illustrated in FIG. 3 as a control characteristic diagram is started.

That is, at the point d where the wheel speed falls below the deceleration state threshold value, the gate valve GV is closed by the command of the control unit 11 (that is, the wheel lock detection signal) and the brake fluid pressure in the wheel cylinders Cd, Cf and the fluid passage 3 is increased. Is contained, and the second valve device DV is opened.

As a result, the pressure reducing piston RP moves toward the back chamber R ₂ side against the spring RS, and the volume of the pressure reducing chamber R ₁ increases, so the brake fluid pressure in the wheel cylinders Cd, Cf decreases and the braking force decreases. To do. At the point e where the wheel speed is recovered and coincides with the deceleration state threshold value, the second valve device DV is closed, so that the brake fluid pressure is kept constant and the braking force also remains constant.

At the point f where the wheel speed is further recovered and coincides with the vehicle speed, for example, the first valve device BV is opened for a minute time t ₁ and
The control unit 11 controls so that the opening and closing operation of t ₂ is repeated and the accumulator hydraulic pressure is supplied to the back chamber R ₂ and the rear chamber T _2.
Issues a command. The magnitudes of the minute times t ₁ and t ₂ are set by the rise adjustment unit 12 provided in the control unit 11.

The pressure reducing piston RP moves stepwise to the pressure reducing chamber R ₁ side by repeating the above-mentioned opening / closing operation, whereby the brake fluid pressures of the fluid passage 3 and the wheel cylinders Cd, Cf are successively increased as shown in FIG. However, the braking force increases.

In this way, the brake fluid pressure is repeatedly reduced, maintained, and increased to prevent wheel lock and reduce the vehicle speed to a desired vehicle speed.

The wheel acceleration slip control for slip prevention at the time of starting is illustrated in FIG. 4 as a control characteristic diagram.
When Fr starts slipping due to a speed difference of a certain value or more with respect to the driven wheel Rr (point g), the cut valve KV and the gate valve GV are closed according to a command from the control unit 11, and the first valve device BV is very small. Open for time t ₃ .

Therefore, the accumulator hydraulic pressure acting on the rear chamber T ₂ pushes the pressure increasing piston TP toward the liquid feeding chamber T ₁ , whereby the hydraulic pressure in the liquid passage 3 is preliminarily increased to P _1. The braking device is put into a state in which it starts to operate (a so-called brake dragging state).

When the acceleration slip state advances and the drive wheel speed reaches the slip threshold value (point h), the first valve device BV is opened for a minute time t ₄ by the acceleration slip detection signal from the control unit 11, and the time t ₅ between the Kukaee closing operation to be closed pulsating manner acts accumulator fluid pressure in the rear chamber T _2, the booster piston TP is moved to the delivering chamber T ₁ side stepwise, by which the liquid The brake fluid pressure in the road 3 and the wheel cylinder Cd of the drive wheel Fr successively increases as shown in FIG. 4, and the acceleration slip decreases as the braking force increases. The opening time t ₄ of the first valve device BV is set to a sufficiently small value, and is set to a value smaller than the opening time t ₁ of the first valve device BV in the wheel lock prevention control, Moreover, since the hydraulic pressure introduced into the rear chamber T ₂ is limited by the throttle 14, the rising rate of the brake hydraulic pressure is a small value suitable for the wheel acceleration slip control.

When the drive wheel speed reaches, for example, the higher peak (point i), the first valve device BV remains closed and the brake fluid pressure is maintained. When the driving wheel speed decreases due to the braking force acting on the wheel cylinder Cd and coincides with the slip threshold, the second valve device DV is opened for a minute time t ₆ by the command of the control unit 11, and at the time t ₇ . The opening / closing operation of closing the chamber is repeated and the hydraulic pressure in the rear chamber T ₂ is discharged to the reservoir 5, and the booster piston TP is stepped in the rear chamber.
It moves to the T ₂ side, and as a result, the brake fluid pressure in the wheel cylinder Cd sequentially drops as shown in FIG. When the driving wheel speed reaches the low peak value (point k), the repetition of the opening / closing operation of the second valve device DV is stopped.

In this way, increasing and maintaining brake fluid pressure, holding and depressurization are repeated and controlled to a suitable driving force that maximizes the adhesion coefficient of the tire and tread, while excessive slip that occurs is rapidly eliminated, The vehicle speed increases.

In the wheel acceleration slip control, points h to i in FIG.
Then, the accumulator hydraulic pressure is supplied to the rear chamber T ₂ ,
Since the throttle 14 is provided between the liquid passage 13 and the rear chamber T ₂ as described above, the rise rate of the accumulator hydraulic pressure is suppressed by this throttle valve, and the accumulator hydraulic pressure is supplied to the liquid feeding chamber T ₁ of the pressure boosting piston TP. The movement toward the front gradually rises to suppress an increase in the braking force, and the braking force corresponding to the driving torque at the time of starting finely suppresses the driving force.

The slip is reduced and the accumulator hydraulic pressure is increased in the rear chamber.
When it is discharged from T ₂ , it bypasses the throttle 14 and is quickly discharged from the liquid inlet / outlet path 13 to the reservoir 5 by the one-way valve 15, and the pressure boosting piston TP quickly returns to the rear chamber T ₂ side. , The driving force control hydraulic pressure decreases rapidly, the braking force decreases rapidly,
The driving torque recovers rapidly. In this way, the slip becomes smaller, and when the desired vehicle speed is reached, the wheel acceleration slip control ends.

In the illustrated embodiment, the pressure intensifying piston TP is when you return to the rearmost end position of the rear chamber T _2, which stroke switch SW provided consisting of those such as a micro switch that operates by detecting, the stroke switch SW The control unit 11 issues a command to close the second valve device DV when the above operation is performed.

When this wheel acceleration slip control is finished by is made to return to a predetermined condition of the last end position of the booster piston TP is always the rear chamber T _2, so that the next control is reliably performed.

The logic circuit 16 including the control unit 11 and the like shows an example,
The present invention is not limited to this, and can be changed by various known techniques.

(Effects of the Invention) The vehicle brake control device according to the present invention is configured as described above, and during normal braking by the brake pedal, the normally closed first valve device and the second valve device DV are used. The pressure reducing piston RP and the pressure increasing piston TP do not operate.

In the wheel lock prevention control, the first valve device BV is controlled to open and close based on the running state of the wheel with respect to the threshold value during deceleration.
And the accumulator hydraulic pressure controlled by the second valve device DV is supplied to the decompression cylinder device RC, and the decompression piston RP operates, so that the decompression piston RP generates a stable anti-locking liquid pressure, and the braking force is suitable. Effective brake control that can be controlled and does not cause wheel lock is performed.

In the wheel acceleration slip control at the time of starting, the pressure reducing piston RP is located on the delivery chamber R ₁ side and does not operate, and the first valve device BV is controlled to be opened / closed based on the traveling state of the drive wheel Fr with respect to the threshold value at the time of starting. And the controlled hydraulic pressure provided by the second valve device DV causes only the pressure increasing piston TP to operate, and this piston TP generates a suitable driving force control hydraulic pressure, which corresponds to the adhesion coefficient between the road surface and the tire. A suitable driving force can be obtained, and the acceleration characteristic with small slip and high efficiency can be obtained.

The first valve device BV and the second valve device DV can be commonly used for both wheel lock prevention control and wheel acceleration slip control, and
What is needed for these controls is a very complicated one mainly consisting of the gate valve GV, the pressure reducing cylinder device RC and the pressure increasing cylinder device TC, and the number of parts is small and the cost is low. , The brake control device has been downsized.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a control circuit diagram,
FIG. 2 is a control block diagram, and FIGS. 3 and 4 are wheel lock prevention control characteristic charts and wheel acceleration slip control characteristic charts 2 ... master cylinder, 3 ... liquid passage, 11 ... control section ,
a ...... fluid path, Cf, Cd ...... wheel cylinders, GV ...... gate valve, R ₂ ...... back chamber, T ₂ ...... rear chamber, R ₁ ...... decompression chamber, T ₁ ......
Liquid transfer chamber, RP ... depressurizing piston, TP ... boosting piston, RC
…… Decompression cylinder device, TC …… Pressure boosting cylinder device, BV…
… First valve device, DV …… Second valve device.

Claims (1)

(57) [Claims] 1. A fluid passage that connects a master cylinder that generates brake fluid pressure to a wheel cylinder of a brake device and the master cylinder, and is closed during wheel lock prevention control during braking or during wheel acceleration slip control. A normally-open type gate valve, a pressure increasing cylinder device and a pressure reducing cylinder device connected to a liquid passage between the gate valve and the wheel cylinder, and the liquid passage is slidable inside the pressure increasing cylinder device and both ends of the liquid passage. A pressure increasing piston that is divided into a liquid feeding chamber and a rear chamber connected to the passage, and a pressure reducing chamber and a back chamber that are slidable inside the pressure reducing cylinder device and are connected to the liquid passage at both ends. The decompression piston, the accumulator that stores hydraulic pressure, and the wheel lock prevention control or the wheel acceleration slip control that are provided between the accumulator and the rear and back chambers. A normally closed first valve device for selectively and selectively introducing the hydraulic pressure of the accumulator to the rear chamber and the back chamber, and a normally closed second valve device between the reservoir and the rear chamber and the back chamber. A brake control device for a vehicle, comprising: