JPH05270375A - Rear wheel braking force control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rear wheel braking force control device capable of readjusting the rear wheel braking force distribution even when the rear wheel braking force is too high for road conditions. [Structure] Pressure sensor 38 for detecting master cylinder pressure
And control valve means 18 ₁ , 18 ₂ , 26, 2 capable of variably setting the break point pressure at which the braking force distribution characteristics of the front and rear wheels change.
7, and front and rear wheel anti-lock brake devices 14, 17, 20, 2 which prevent the front and rear wheels from locking.
2, break point pressure setting means 37 for setting the master cylinder pressure detected by the pressure sensor 38 as the break point pressure when the rear wheel anti-lock brake device is operated, and the master detected by the pressure sensor 38. When the cylinder pressure becomes equal to or higher than the break point pressure set by the break point pressure setting means, the control valve means is operated to change the brake force distribution characteristics of the front and rear wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel braking force control device for controlling distribution of front wheel braking force and rear wheel braking force.

[0002]

2. Description of the Related Art When a brake pedal is depressed, a brake hydraulic pressure generated in a master cylinder (hereinafter referred to as a master cylinder pressure) is transmitted to four wheel cylinders, and a braking force is generated in each wheel.

If the brake pedal is stepped on more, the braking force generated on each wheel will increase, and the deceleration of the vehicle will increase. When the deceleration of the vehicle is increased, the load on the rear wheels is reduced, so that the groundability of the rear wheels is reduced. Braking such that the deceleration of the vehicle becomes large in this way (high G braking)
Under a braking condition that causes the rear cylinder, if the master cylinder hydraulic pressure is distributed and transmitted to the wheel cylinders of the front and rear wheels with almost the same distribution, the ground contact of the rear wheel is reduced, and the rear wheel locks first. However, there is a problem that the braking stability of the vehicle deteriorates.

Therefore, when the braking force is small, the master cylinder pressure is transmitted as it is to the wheel cylinder of the rear wheel,
When the master cylinder pressure exceeds the set pressure, the rear wheel wheel
A proportioning valve (PCV) that functions to prevent the early locking of the rear wheels by reducing the rate of increase in hydraulic pressure transmitted to the cylinder is incorporated in the brake system.

Further, a bypass valve for bypassing this proportioning pulp is provided, and the bypass valve is opened up to the break point pressure higher than the set pressure described above, and when the pressure exceeds the set pressure, the bypass valve is closed and the proportioning valve is opened. A rear wheel braking force control device has been considered in which the braking force distribution to the rear wheels is suitably controlled by variably setting the pressure at the break point so that the braking force can be effectively utilized.
315660).

[0006]

The setting of the break point pressure in such a rear wheel braking force control device predicts the load of the rear wheel, for example, by detecting the displacement of the suspension, and based on this rear wheel load, The break point pressure for closing the bypass valve that bypasses the proportioned pulp is set. However, depending on road surface conditions, the rear wheels may start slipping before the set break point pressure is reached.

The present invention has been made in view of the above points, and an object thereof is to lower the break point pressure when a sign that the rear wheel is locked is detected before the break point pressure that has been set once is reached. An object of the present invention is to provide a rear wheel braking force control device capable of suitably controlling the braking force distribution to the rear wheels without causing the rear wheels to lock under any road surface condition by adjusting.

[0008]

A rear wheel braking force control device according to a first aspect of the present invention comprises a master cylinder pressure detecting means for detecting a master cylinder pressure, and a rear wheel braking force with respect to a front wheel braking force. The control valve means capable of variably setting the pressure at the break point, the rear wheel anti-lock brake device for preventing the rear wheel from being locked, and the above-mentioned when the rear wheel anti-lock brake device is operated. The break point pressure setting means for setting the master cylinder pressure detected by the master cylinder pressure detecting means as the break point pressure, and the master cylinder pressure detected by the master cylinder pressure detecting means are set by the break point pressure setting means. When the pressure exceeds the break point pressure, the control valve means is operated to reduce the ratio of the braking force of the rear wheels to the braking force of the front wheels.

According to a second aspect of the present invention, there is provided a rear wheel braking force control device in which the ratio of the brake force of the rear wheel to the brake force of the front wheel and the master cylinder pressure detecting means for detecting the master cylinder pressure is reduced. Control valve means capable of variably setting the point pressure,
The slip ratio calculating means for calculating the slip ratio of the rear wheels, and the master cylinder pressure detected by the master cylinder pressure detecting means when the slip ratio of the rear wheels calculated by the slip ratio calculating means becomes a predetermined value or more, When the master cylinder pressure reaches the break point pressure set by the break point pressure setting means, the control valve means is operated to operate the rear wheel against the brake force of the front wheel. And a control means for reducing the ratio of the breaking force.

The master cylinder pressure detected by the master cylinder pressure detecting means when the holding signal is output to the rear wheel anti-lock brake device in the rear wheel braking force control device according to the third aspect of the invention is the break point. After the pressure is set, when the pressure reduction signal is output to the rear wheel anti-lock brake device, the already set break point pressure is updated to be further reduced.

In the rear wheel braking force control device according to the fourth aspect, the break point pressure setting means is a rear wheel antilock brake.
After setting the master cylinder pressure detected when the key device is operated as the above break point pressure, it is already set when the operation signal is output to the rear wheel anti-lock brake device earlier than the front wheel anti-lock brake device. It has been updated to further reduce the break point pressure.

The control valve means and the rear wheel anti-skid brake device in the rear wheel braking force control device according to the fifth aspect are provided for each of the left and right rear wheels, and the break point pressure setting means is the rear wheel. The break point pressure is updated for each of the left and right wheels of the, and the updated break point pressure is held for a predetermined time.

[0013]

According to the first aspect of the present invention, the master cylinder pressure when the rear wheel anti-lock brake device is operated is set as the break point pressure, and when the master cylinder pressure exceeds the break point pressure, the control valve means is activated. It is operated to reduce the ratio of the braking force of the rear wheels to the braking force of the front wheels.

According to the second aspect of the present invention, the master cylinder pressure is set as the break point pressure when the slip ratio of the rear wheels calculated by the slip ratio calculating means exceeds a predetermined value, and the master cylinder pressure is set as the break point pressure. In the above case, the control valve means is operated to reduce the ratio of the braking force of the rear wheels to the braking force of the front wheels.

According to a third aspect of the present invention, when the pressure reducing signal is output to the rear wheel anti-lock brake device, the master cylinder pressure is set when the holding signal is output to the rear wheel anti-lock brake device. The pressure at the break point is updated so as to be further lowered, and even if the break point pressure is set to be relatively high, the pressure is updated to be low to effectively prevent the rear wheel from being locked.

In claim 4, after the break point pressure is set by the master cylinder pressure when the rear wheel anti-lock brake device is operating, the rear wheel anti-lock brake device is faster than the front wheel anti-lock brake device. When the operating signal is output to the rear wheel, the pressure at the break point is updated to be further lowered, and even when the break point pressure is set to be relatively high, the pressure is updated to be low to effectively prevent the rear wheel from being locked. ..

In the fifth aspect, the control valve means and the rear wheel anti-skid brake device are provided for each of the left and right rear wheels, and the break point pressure setting means sets the break point pressure for each of the left and right rear wheels. By updating and maintaining the updated break point pressure for a predetermined time, it is possible to obtain an optimum rear wheel braking force even during split road or turning braking, and by maintaining the break point pressure for a predetermined time, It prevents changes in the braking feel.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rear wheel braking force control system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a rear wheel braking force control device according to an embodiment of the present invention, FIGS. 2 and 3 are flowcharts for explaining the operation of the same embodiment, and FIG. 4 is a controller. FIG. 5 is a block diagram for explaining the functional means of FIG. 5, and FIG. 5 is a diagram showing the input / output characteristics of the proportioning valve.

In FIG. 1, reference numeral 11 is a brake pedal. The pedaling force of the brake pedal 11 is amplified by the booster 12 and then transmitted to the tandem master cylinder 13.

The master cylinder 13 is provided with two hydraulic pressure generators (not shown) which generate a brake hydraulic pressure according to the amount of depression of the brake pedal 11. One hydraulic pressure generator is ABS (anti-skid brake system) 1
4 through the pipe 15 attached to the front wheel of the left front wheel
Wheel cylinder 16 ₄ for the right rear wheel through a pipe 19 connected to the ABS 17 and PCV 18 ₂ while being connected to the cylinder 16 ₁ and branched from the middle of the pipe 15.
Connected to.

Further, the other hydraulic pressure generator right front wheel Hui via a pipe 21 which ABS20 is attached - is connected to Rushirinda 16 _2, branched ABS22 and PCV18 ₁ is attached from the middle of the pipe 21 It is connected to the wheel cylinder 16 ₃ of the left rear wheel via a pipe 23.

When the braking force is small, the PCVs 18 ₁ and 18 ₂ transmit the master cylinder pressure as it is to the wheel cylinder of the rear wheel, and when the master cylinder pressure exceeds the set pressure, it is transmitted to the wheel cylinder of the rear wheel. It is a known proportioning valve that functions to reduce the rate of pressure increase.

That is, as shown by the solid line C in FIG. 5, the characteristic curves of the PCVs 18 ₁ and 18 ₂ have an inclination of "1" in the region where the master cylinder pressure is smaller than the set pressure Po, and the master cylinder pressure is the set pressure Po. When it exceeds, the inclination of the rear wheel braking force with respect to the master cylinder pressure changes so as to become smaller. This set pressure Po is uniquely determined by the mechanical requirements of the PCVs 18 ₁ and 18 ₂ .

A bypass pipe 24 is provided between the upstream side and the downstream side of the PCV 18 ₁ , and a bypass pipe 25 is provided between the upstream side and the downstream side of the PCV 18 ₂ . The bypass pipes 24 and 25 are provided with PCV bypass valves 26 and 27, which are normally open electromagnetic on-off valves, respectively.

Therefore, the PCV bypass valves 26, 2
By setting the master cylinder pressure for closing 7 to be variable, the rear wheel braking force can be controlled within the shaded area in FIG. 5, which is higher than the braking force indicated by the ideal braking force curve B. It is possible to generate braking force on the rear wheels.

Further, 31 is a wheel speed sensor for detecting the wheel speed VFL of the left front wheel, 32 is a wheel speed sensor for detecting the wheel speed VFR of the right front wheel, and 33 is a wheel speed VRL of the left rear wheel.
And a wheel speed sensor 34 for detecting the rear wheel speed V of the right rear wheel.
A wheel speed sensor that detects RR and a vehicle speed sensor 35 that detects a vehicle speed V. Wheel speeds VFL, VFR, VRL, VRR
The signal and the vehicle speed V signal are input to the ABS controller 36.

The ABS controller 36 is composed of a microcomputer and its peripheral circuits, and the slip ratio of each wheel is determined based on the wheel speeds VFL, VFR, VRL, VRR and the vehicle speed V. ABS valve 14, 20, 22, 1 provided for each wheel
The ABS signals a1 to a4 are output to 7 respectively. This A
The BS signals a1 to a4 are, for example, pressure boosting signals for injecting the brake fluid into the wheel cylinders 16 _{1 to} 16 ₄ depending on the signal level, and the brake signals in the wheel cylinders 16 _{1 to} 16 _4.
Hold signal for holding liquid, wheel cylinders 16 ₁ to 1
Shake 6 ₄ - key solution under reduced pressure signal means respectively removing the. The ABS controller 36 first outputs a hold signal and then a pressure reduction signal when the wheel slip ratio exceeds a predetermined value.

The ABS controller 36 receives the ABS signal a1.
To a4 are output to the controller 37 including, for example, a microcomputer and its peripheral circuits. Further, the master cylinder pressure P output from the pressure sensor 38 for detecting the master cylinder pressure PM provided in the pipe 15 is output.
The M signal is input to the controller 37. The controller 36 independently controls the opening / closing control of the PCV bypass valves 26 and 27.

This controller 37 is a PCV of the left rear wheel.
The master cylinder pressure that closes the PCV bypass valve 26 that bypasses 18 ₁ , that is, the left rear wheel break point pressure PL
Memory m1, closing the PCV bypass valve 27 for bus passes the PCV18 ₂ of the right rear wheel master cylinder pressure for storing, i.e. memory m2, braking 0.6G a high μ road for storing crossover pressure PR of the right rear wheel The memory m3 for storing the break point pressure P1 in the case of performing The controller 37 stores a control program for setting the break point pressures PL and PR in the memories m1 and m2 based on the input ABS signals a1 to a4. The controller 36 has a predetermined sampling time. The master cylinder P and the break point pressures PL and PR set in the memories m1 and m2 are compared for each case, and when "P≥PL", the PCV bypass valve 2 for bypassing the PCV18 _{1 of the} left rear wheel 2
When 6 is closed and "P≥PR", PCV of the right rear wheel
The PCV bypass valve 27 that bypasses 18 ₂ is controlled to be closed.

For example, as shown in FIG. 5, the break point pressure PL
When (P R) is set to a pressure P1 higher than the set pressure Po, the PCV bypass valve 26 (27) is opened until the master cylinder pressure becomes P1, so the rear wheel braking force is indicated by A. The rear wheel braking force increases.

The flow charts shown in FIGS. 2 and 3 are control programs for setting a break point pressure PL for closing the PCV bypass valve 26 that bypasses the PCV 18 ₁ of _one of the rear wheels, for example, the left rear wheel. The flow chart for setting the break point pressure PR that closes the PCV bypass valve 27 that bypasses the PCV 18 ₂ of the right rear wheel.
Since the chart has the same contents, its description is omitted.

Next, the operation of the embodiment of the present invention configured as described above operates. First, the pressure P1 stored in the memory m3 is set as an initial value in the memory m1 that stores the break point pressure PL that closes the PCV bypass valve 26 that bypasses the PCV 18 _{1 of the} left rear wheel (step S1). The ABS output to the ABS valve 22 on the left rear wheel
The signal a3 is judged and it is judged whether the signal is a holding signal (step S2). In the judgment of this step S2, "YE
If it is determined to be "S", the ABS valve 1 on the left front wheel
4 to determine the ABS signal a1 output to
Is operating, that is, whether the holding signal or the pressure reducing signal is output to the device 14 (step S
3). If it is determined in step S3 that the ABS valve 14 on the left front wheel is not operating, step S4
Through the subsequent processing, the processing for updating the break point pressure PL set in the memory m1 in step S1 is performed. That is, when it is determined that the left rear wheel is slipping earlier than the left front wheel, a correction process is performed to lower the break point pressure PL of the left rear wheel. Specifically, step S3
When it is determined to be "NO" in step S4, the master cylinder pressure PM detected by the pressure sensor 38 is read and the memory m1 is updated (steps S4 and S5). Then, the timer 1 starts the timing operation, and A is output to the ABS valve 22 on the left rear wheel before the timer 1 counts a predetermined time.
When the depressurization signal is detected as the BS signal a3 (steps S6 to S8), the process proceeds to step S9 and subsequent steps, and a correction process is performed to further lower the break point pressure PL of the left rear wheel.

By the way, the pressure reducing signal is not output as the ABS valve signal a3 output to the ABS valve 22 of the left rear wheel within the predetermined time counted by the timer 1 after the content of the memory m1 is updated in step S5 described above. In this case, the process returns from step S8 to step S7 and the process is repeated until the timer 1 counts a predetermined time.
The break point pressure PL set to m1 is held at the value updated in step S5. That is, if the slip of the rear wheel is progressing, A output to the ABS valve 22 of the left rear wheel is output.
The BS signal a3 is switched from the hold signal to the pressure reduction signal. However, the fact that the pressure reduction signal does not occur within a predetermined time after the hold signal is output means that the rear wheels have not slipped. It is determined that the braking force distribution to the rear wheels is appropriate, and the break point pressure PL is maintained for a predetermined time. When the timer 1 finishes counting the predetermined time in step S7, the process returns to step S1 and the same process is repeated.

By the way, in the judgment of the step S8, "Y
ES ", that is, the ABS signal a output to the ABS valve 22 on the left rear wheel before the timer 1 counts a predetermined time.
When the pressure reduction signal is detected as 3, the processing for updating the break point pressure PL set in the memory m1 to a further lowering direction by a map (not shown) is performed (step S).
9). Then, the time counting operation of the timer 2 is started, and the operation signal is not output as the ABS signal a1 output to the ABS valve 14 of the left front wheel before the timer 2 counts a predetermined time, that is, the holding signal is also depressurized. ABS valve 22 on the left rear wheel with no signal output
When the actuation signal, that is, the holding signal or the pressure reducing signal is output as the ABS signal a3 output to, the break point pressure PL set in the memory m1 is set to zero by proceeding to the processing after step S14 described later. Move to processing.

That is, as the case for setting the break point pressure PL to zero, the break point pressure P is set in the above-described step S9.
Only after L is set to be lowered, the operation signal is output only to the left rear wheel within a predetermined time. In such a case, since the braking force of the left rear wheel is too high, it is judged that the left rear wheel is slipping, and the break point pressure PL is reduced to zero in order to further reduce the braking force of the rear wheel.

The operation signal (holding signal or pressure reducing signal) is output as the ABS signal a1 output to the ABS valve 14 of the left front wheel within the predetermined time counted by the timer 2 after the content of the memory m1 is updated in step S9. Is output, or when the operation signal (holding signal or pressure reduction signal) is not output as the ABS signal a1 output to the ABS valve 14 of the left front wheel, the ABS output to the ABS valve 22 of the left rear wheel. When the operation signal is not output as the signal a3, the flow returns to step S11 described above and the process is repeated until the timer 2 counts a predetermined time and the break point pressure PL is set in the memory m1.
Is held at the value set in step S9. That is,
When the ABS valve 14 on the left front wheel is activated within a predetermined time, the pressure AB at the break point is maintained for a predetermined time.
The control of the S controller 36 performs a process for preventing the front wheels from slipping.

By the way, when it is judged "YES" in step S13, the break point pressure PL set in the memory m1 is set.
Is set to zero, and the time counting operation of the timer 3 is started.
Until the timer 3 counts a predetermined time, the memory
The break point pressure PL set to m1 is held at zero.

That is, the break point pressure P set in the memory m1
Since the condition of "P≥PL" is always satisfied when L is set to zero, the controller 37 can always close the PCV bypass valve 26. For this reason, the PCV 18 ₁ always operates, the braking force distribution shown by the solid line C in FIG. 5 is made due to the characteristics of the PCV 18 ₁ , and the break point pressure is maintained at Po shown in FIG. The slip ratio is effectively suppressed.

When the timer 3 counts a predetermined time and the result of the determination in step S16 is "YES", the process returns to step S1 and the initial value P1 of the break point pressure PL is set in the memory m1. It

That is, after the pressure P1 as shown in the figure is set as the break point pressure PL, when the rear wheel slip is detected by the ABS signal, the break point pressure is gradually decreased. Even after the break point pressure is once set, the break point pressure can be lowered and the rear wheel braking force can be adjusted so as to be increased within a range in which the rear wheel does not slip.

Further, the left and right PCV bypass valves 2
Since the break point pressures PL and PR for closing 6 and 27 are set independently to control the opening and closing, it is optimal even when braking on a road surface where the friction coefficient of the road surface with respect to the left and right wheels is different, that is, on a split road or during turning braking. It is possible to obtain a proper braking force.

Further, after the break point pressure is set, the value is held for a certain period of time by the timer management, so the setting change of the target value can be reduced and the change of the braking feeling can be prevented. You can

The function of the controller 36 is shown in a block diagram in FIG. In FIG.
The holding signal MAI (RL) of the left rear wheel is ABS controller 3
If the ABS signal a3 output from 6 to the ABS valve 22 is a holding signal, it becomes H level, and if it is any other signal, it becomes L level.
(FL) is ABS controller 14 to ABS valve 14
If the ABS signal a1 output to the terminal is a decompression signal, it is at H level, and if it is other signal, it is at L level. The MAI (FL) is a logical signal from the ABS controller 36 to the ABS
If the ABS signal a1 output to the valve 14 is a holding signal, it becomes H level, and if it is any other signal, it becomes L level. The left rear wheel pressure reduction signal REL (FL) is AB.
If the ABS signal a1 output from the S controller 36 to the ABS valve 14 is a holding signal, it is at H level, and if it is any other signal, it is at L level.

The hold signal MAI (RL) is input to one input terminal of the AND circuit 41, and the reduced pressure signal REL (FL) or the hold signal MAI (FL) is input to the other input of the AND circuit 41 via the inverter 42. Input to the terminal.

The output of the AND circuit 41 is input to the input terminal of the timer 1. The output of the AND circuit 41 of the timer 1 is H
After reaching the level, the H level state is maintained for a predetermined time.

The output of the timer 1 is input to one input terminal of the AND circuit 43. The reduced pressure signal REL (RL) is input to the other input terminal of the AND circuit 43. The output of the AND circuit 43 is input to the timer 2. The timer 2 holds the H level for a predetermined time after the output of the AND circuit 43 rises to the H level.

The output of the timer 1 is the second of the break point pressure.
The target value P2 is input to the holding unit 44. The master cylinder pressure PM output from the pressure sensor 37 is input to the holding portion 44. This holding unit 44 holds the master cylinder pressure PM only while the output of the timer 1 is in the H level state.

The output of the holding unit 44 is input to the holding unit 45. This holding portion 45 has a third target value P3 of the break point pressure.
Is input to the holding unit 45 that holds the. The output of the timer 2 described above is input to the holding unit 45, and the timer 2
While the output of is in the H level state, the value obtained by multiplying the break point pressure PM output from the holding unit 44 by “0.7” is held.

The second target value P held in the holding unit 44
2 and the third target value P3 held in the holding unit 45 are input to the minimum value selection unit 46. An initial value P1 of the break point pressure set in the memory m1 is input to the minimum value selection unit 46.

Further, the REL (FL) signal is input to the first input terminal of the AND circuit 48 via the inverter 47, and RE
The L (RL) signal and the output of the timer 2 are input to the second and third input terminals of the AND circuit 48, respectively.

The output of the AND circuit 48 is input to the timer 3. The timer 3 holds the H level for a predetermined time after the output of the AND circuit 48 becomes the H level. The output of the timer 3 is the holding unit 4 that holds the fourth target value P4 of the break point pressure.
9 is input. An initial value P1 of the break point pressure stored in the memory m3 is input to the holding unit 49, and the holding unit 49 holds a value obtained by multiplying the initial value P1 by 0.01 as the fourth target value P4. The output of the holding unit 49 is input to the minimum value selection unit 46. In this way, the initial value P1 is set to 0.
Since it has been known in advance that the pressure becomes smaller than the set pressure Po in FIG. 5 when multiplied by 01, it is multiplied by 0.01.
As the target value P4, zero may be set in the same manner as in the flow chart described above, or may be a value smaller than Po. The breaking point pressures P1 to P4 are shown in FIG.

Further, the break point pressure PM is "0.7 times" in the holding portion 45.
It may be obtained by a map like the processing of G. It goes without saying that the opposite can be applied to the processing of the flow chart described above.

The minimum value selection unit 46 selects the minimum value from the first to fourth target values P1 to P4 to be input and selects the target pressure PL.
To the comparison unit 50. The comparison unit 50 compares the master cylinder pressure PM output from the pressure sensor 37 with the target pressure PL output from the minimum selection unit 46, and “PM ≧
If it is "PL", a control start signal for closing the PCV bypass valve 26 is output to a drive circuit (not shown).

In the above embodiment, the break point pressure is adjusted based on the ABS signals a1 to a4 output from the ABS controller 36, but the slip of each wheel calculated by the ABS controller 36 is adjusted. Rate the controller 37
Alternatively, if the slip ratio exceeds a predetermined value instead of the process of step S2, the same process may be performed.

[0055]

As described above in detail, according to the present invention, when a sign that the rear wheels are locked is detected before the set break pressure is reached, the break pressure is adjusted to be lowered. As a result, it is possible to provide a rear wheel braking force control device that can appropriately control the braking force of the rear wheels without causing the rear wheels to be locked under any road surface condition.

[Brief description of drawings]

FIG. 1 is a block diagram showing a rear wheel braking force control device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.
Part of the.

FIG. 3 is a flowchart for explaining the operation of the embodiment.
Part of the.

FIG. 4 is a block diagram for explaining the functional means of the controller.

FIG. 5 is a diagram showing input / output characteristics of a proportioning valve.

[Explanation of symbols]

12 ... Booster device, 14, 17, 20, 22 ... ABS valve, 16 _{1 to} 16 ₄ ... Wheel cylinder, 18 ₁ , 18
₂ ... PCV, 26, 27 ... PCV bypass valve, 36
... ABS controller, 37 ... controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromichi Yasunaga Inventor Hiromichi Yasunaga 5-3-8, Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (5)

[Claims] 1. A master cylinder pressure detecting means for detecting a master cylinder pressure, and a control valve means capable of variably setting a breaking pressure at which a ratio of a rear wheel breaking force to a front wheel breaking force decreases. A rear wheel anti-lock brake device for preventing the rear wheel from being locked, and a master cylinder pressure detected by the master cylinder pressure detecting means when the rear wheel anti-lock brake device is operated as the break point pressure. When the master cylinder pressure detected by the break point pressure setting means and the master cylinder pressure detecting means exceeds the break point pressure set by the break point pressure setting means, the control valve means is operated to move the front wheel. A rear wheel braking force control device comprising: a control means for reducing the ratio of the braking force of the rear wheel to the braking force. 2. A master cylinder pressure detecting means for detecting a master cylinder pressure, and a control valve means capable of variably setting a break point pressure at which a ratio of a brake force of a rear wheel to a brake force of a front wheel decreases. The slip ratio calculating means for calculating the slip ratio of the rear wheels, and the master cylinder pressure detected by the master cylinder pressure detecting means when the slip ratio of the rear wheels calculated by the slip ratio calculating means exceeds a predetermined value. The break point pressure setting means for setting the break point pressure, and when the master cylinder pressure reaches the break point pressure set by the break point pressure setting means, the control valve means is operated to operate the rear wheel against the brake force of the front wheel. And a control means for decreasing the ratio of the braking force of the rear wheel. 3. The break point pressure setting means sets the master cylinder pressure detected by the master cylinder pressure detecting means as the break point pressure when a holding signal is output to the rear wheel anti-lock brake device. 2. The rear wheel braking force control device according to claim 1, wherein when the pressure reduction signal is output to the rear wheel anti-lock brake device, the pressure at the break point that has already been set is further updated. 4. A front wheel anti-lock brake device for preventing the front wheel from being locked, wherein the break point pressure setting means uses the master cylinder pressure detected when the rear wheel anti-lock brake device is operated. After setting as the break point pressure, when the operation signal is output to the rear wheel anti-lock break device earlier than the front wheel anti-lock break device, the set break pressure is updated to be further lowered. The braking force control device according to claim 1. 5. The control valve means and the rear wheel anti-skid brake device are provided for each of the left and right rear wheels, and the break point pressure setting means updates the break point pressure for each of the left and right rear wheels. The braking force control device according to claim 1, wherein the updated break point pressure is maintained for a predetermined time.