JPH1086801A - Braking force distributing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a braking force by an ideal distribution without causing any complication of a hydraulic circuit nor increase in costs. SOLUTION: A sensor 9 detecting a fluid pressure of a master cylinder 2 is arranged. A control device ECU 30, which is arranged in the subject system, controls a control fluid pressure, which is fed from an external fluid pressure supply source 4 to a wheel cylinder 3, by means of a fluid pressure control valve on the basis of the detection result from the sensor 9. A target wheel cylinder pressure, which is used for bringing a braking force close to an ideal distribution, is varied according to a pressure increasing speed of the master cylinder pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force distribution system for controlling a hydraulic pressure of a brake for a vehicle such as an automobile.

[0002]

2. Description of the Related Art In recent years, a brake fluid pressure control device having an external fluid pressure supply source is known. The brake fluid pressure control device equipped with this external fluid pressure supply source detects the master cylinder pressure when the brake pedal is depressed, and, based on the result of the detection, detects the master cylinder pressure according to the master cylinder pressure from the external fluid pressure supply source. It supplies hydraulic pressure to the wheel cylinders of the wheels, and this type of brake hydraulic pressure control device controls the hydraulic pressure from an external hydraulic pressure supply source to the wheel cylinders of each wheel to control the wheel pressure. It is known to incorporate an anti-lock brake system to prevent locking.

By the way, when a brake is applied, the load applied to the front wheels of the vehicle increases, while the load applied to the rear wheels decreases, and the rear wheels tend to lock in advance. For this reason, in the above-mentioned brake fluid pressure control device, a system having a braking force distribution control function provided with a proportioning valve has been developed. This proportioning valve operates so that when the input-side hydraulic pressure exceeds a certain value, the output-side hydraulic pressure rise is suppressed at a predetermined rate in relation to the input-side hydraulic pressure rise. By interposing this in the hydraulic circuit connecting the master cylinder and the wheel cylinder on the rear wheel side, the distribution of the braking force of the front and rear wheels can be made closer to the ideal distribution, and the rear wheel leading lock is prevented. Become so.

[0004]

By the way, in the above-described brake fluid pressure control device, when a proportioning valve is provided to add a braking force distribution control function,
There is a problem that the hydraulic circuit becomes complicated and the cost increases.

The present invention has been made in view of the above circumstances, and it is possible to control the braking force of the wheels to an ideal distribution at low cost without complicating the hydraulic circuit of the brake hydraulic pressure control device. It is intended to provide a possible braking force distribution system.

[0006]

According to a first aspect of the present invention, there is provided a braking force distribution system comprising: a master cylinder for generating a hydraulic pressure by operating a brake pedal; and a sensor for detecting the master cylinder pressure. A brake fluid pressure control device that applies a control fluid pressure from an external fluid pressure supply source to a wheel cylinder in response to a detection signal from the sensor. A controller for controlling a control hydraulic pressure of an external hydraulic pressure supply source is provided to gradually bring the cylinder pressure closer to the target wheel cylinder pressure.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brake fluid pressure control device provided with a braking force distribution system according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a brake pedal, and the master cylinder 2 generates a hydraulic pressure when the brake pedal 1 is depressed. Reference numeral 3 denotes a wheel cylinder that generates a braking force by hydraulic pressure, reference numeral 4 denotes an external hydraulic pressure supply source, and reference numeral 5 denotes an action from the external hydraulic pressure supply source 4 to the wheel cylinder 3 based on the output of the master cylinder 2. This is a hydraulic pressure control valve for adjusting the pressure.

An accumulator 7 is connected to a pipe line on the output side of the master cylinder 2 via a switching valve 6, and the wheel cylinder 3 is connected via a switching valve 8 as a fail-safe valve. . In addition,
Reference numerals 9 and 10 denote sensors for measuring the hydraulic pressure, and their outputs are supplied to the control unit ECU 30. The control device ECU 30 controls the hydraulic pressure control valve 5 based on the pressure detected by the sensor 9.
To control the drive current of the coil (described later) that operates the.

The internal structure of the external hydraulic pressure supply 4 will be described. Reference numeral 4a denotes a hydraulic pump.
a is driven by a motor 4c to generate a hydraulic pressure. An accumulator 4b is connected to the output side of the hydraulic pump 4a so as to store the generated high hydraulic pressure. The hydraulic pump 4a is provided with a reservoir 4
The liquid sucked from d is pressurized and supplied to the liquid pressure control valve 5. Reference numeral 4E denotes a pressure sensor for detecting the pressure in the accumulator 4b, and a control unit ECU based on the detection result from the pressure sensor 4E.
When the pressure of the accumulator 4b becomes a predetermined value or less, the motor 30 drives the motor 4c to pressurize the hydraulic pump 4a. Reference numeral 4F denotes a relief valve for releasing excess hydraulic pressure in the accumulator 4b to the reservoir 4d.

Next, the structure of the hydraulic control valve 5 will be described. Reference numeral 11 denotes a body, and a valve hole 12 is provided inside the body 11, and a hydraulic pressure supply port 13, a drain port 14, and an output port 15 communicating with the valve hole 12 are provided. It is open in the valve hole 12. That is, the hydraulic pressure supply port 1
3 is connected to an external hydraulic pressure supply source 4, the drain port 14 communicates both ends of the valve hole 12 with each other and is connected to a reservoir 4d and is opened to the atmosphere, and the output port 15 is connected to the wheel through a fail-safe valve 8. Cylinder 3
It is connected to the.

A spool 16 is slidably housed in the valve hole 12. The center of the spool 16 is reduced in diameter, and forms an annular communication groove 16a for communicating the hydraulic pressure supply port 13 with the output port 15. By providing the annular communication groove 16a, a variable throttle s is formed between the hydraulic pressure supply port 13 and the spool 16, and a variable throttle t is defined between the drain port 14 and the spool 16. Is formed. Therefore, when the spool 16 moves to the left in the figure, the variable throttle s opens and the variable throttle t closes, and the pressure at the output port 15 increases. When the spool 16 moves to the right in the figure, the pressure increases. Decrease.

The output of the output port 15 is connected to a reaction chamber 18 at one end of the hydraulic pressure control valve 5 through a pipe 17 branched from a pipe toward the wheel cylinder 3. A reaction force generating means 19 is provided therein.
The reaction force generating means 19 is fitted into the end of the valve hole 12, and a pin 20 projecting from the center of the end of the spool 16 is slidably inserted into a through hole provided in the center. ing. Further, a compression spring 21 is provided between the reaction force generating means 19 and the spool 16 as means for applying an elastic force to the spool 16 rightward in the drawing.

A control force generating means 22 is provided at the other end of the pressure control valve 5. This control force generating means 2
2 is a mover 23 provided coaxially with the valve hole 12 and movable in the axial direction, a coil 24 and a yoke 25 provided to apply a thrust to the mover 23 in the axial direction. A compression spring 26 is provided between the mover 23 and the yoke 25 to apply an elastic force to the left in the figure.

Reference numeral 27 denotes a pipeline operated to apply the pressure of the output port 15 to the fail-safe valve 8 to connect the output port 15 to the wheel cylinder 3, and reference numeral 28 denotes a valve for switching the pressure of the output port. 6 is a pipe line operated to connect the master cylinder 2 to the accumulator 7 by giving it to the accumulator 7.

A pipeline between the accumulator 4b of the external hydraulic pressure supply source 4 and the hydraulic pressure supply port 13 of the hydraulic pressure control valve 5 having the above structure is driven to open and close by a signal from the control unit ECU30. A hydraulic passage opening / closing valve 29 is provided. That is, the supply passage of the hydraulic pressure from the external hydraulic pressure supply source 4 to the hydraulic control valve 5 is opened and closed by the hydraulic passage opening / closing valve 29. A hydraulic pressure amplifying device 31 is provided between the output port 15 of the hydraulic pressure control valve 5 and the switching valve 8.

The hydraulic pressure amplifying device 31 includes a cylinder body 41 having two cylinder portions 41a and 41b having different diameters, a large-diameter plunger portion 34a and a small-diameter plunger portion 3.
4b, the large-diameter plunger portion 34
a is a large-diameter cylinder portion 41a, and a small-diameter plunger portion 34b
The plunger body 34 is slidably disposed on the small-diameter cylinder portion 41b. The large-diameter cylinder portion 41a and the large-diameter plunger portion 34
a is defined as the input-side hydraulic chamber 33, the small-diameter cylinder portion 41b and the small-diameter plunger portion 34b.
The space defined by the above is an output side hydraulic chamber 35. The output port 15 of the hydraulic pressure control valve 5 is connected to the input-side hydraulic chamber 33 via the flow path 32, and the switching valve 8 is connected to the output-side hydraulic chamber 35 via the flow path 36. Have been.

A compression spring is provided in the output-side hydraulic chamber 35, and the plunger body 34 is urged toward the large-diameter cylinder portion 41a by the compression spring.

The input hydraulic chamber 33 of the hydraulic amplifying device 31 is connected to an external hydraulic pressure source 4 through a hydraulic pressure control valve 5.
, The pressurized brake fluid is supplied, and the hydraulic pressure causes the plunger body 34 to be pressed and slid in the direction of arrow A in the figure against the urging force of the compression spring. Thus, the output-side hydraulic chamber 35 is compressed by the small-diameter plunger portion 34b, and the internal brake fluid is pressurized and sent to the switching valve 8 via the flow path 36.

Here, the hydraulic pressure of the brake fluid sent out from the output side hydraulic chamber 35 through the flow path 36 is increased by the ratio of the area of each of the plungers 34a and 34b. That is, the relationship between the hydraulic pressure Pin in the input-side hydraulic chamber 33 and the hydraulic pressure Pout in the output-side hydraulic chamber 35 depends on the input-side hydraulic chamber 3.
3, the pressure receiving area of the large diameter plunger portion 34a is Ain, and the pressure receiving area of the small diameter plunger 34b of the output side hydraulic chamber 35 is A.
If it is out, it can be expressed by the following equation.

Pout = Ain / Aout · Pin

That is, the brake fluid is pressurized by the ratio of the respective pressure receiving areas of the large-diameter plunger 34a and the small-diameter plunger 34b.

Next, the operation of the brake fluid pressure control device having the above configuration will be described. When the brake pedal 1 is depressed, the liquid is pushed out from the master cylinder 2, and this pressure is detected by the sensor 9. When the controller 9 detects that the brake fluid has been pushed out of the master cylinder 2 by the sensor 9, the control device ECU 30 supplies a control current to the hydraulic passage opening / closing valve 29 to open the hydraulic passage opening / closing valve 29, and The flow path between the pressure supply source 4 and the hydraulic pressure control valve 5 is communicated. Further, the control device ECU 30 controls the exciting current of the coil 24 based on the pressure detected by the sensor 9, and the mover 23 moves to the left in FIG. The spool 16 moves in the same direction.
By this movement, the reaction force spring 21 is compressed, and FIG.
An elastic force is generated in the middle right direction, applying a reaction force to the spool 16 in accordance with the amount of elastic deformation, and closing the variable throttle t to cut off communication between the annular communication passage 16a and the drain port 14.

When the spool 16 moves further to the left, the variable throttle s is opened to communicate the annular communication passage 16 a with the hydraulic pressure supply port 13, and a high brake hydraulic pressure is applied from the output port 15 to the hydraulic amplifying device 31. It is sent to the input side hydraulic chamber 33. As a result, the plunger body 34 of the hydraulic pressure amplifying device 31 moves in the direction of the arrow A in the figure against the urging force of the compression spring 37, and pressurizes from the output-side hydraulic chamber 35 based on the above-described equation. The supplied brake fluid is supplied to the wheel cylinder 3 via the switching valve 8, and the wheels are braked. In a state where the brake fluid pressure is normally applied from the output port 15 via the fluid pressure amplifying device 31, since the switching valves 6 and 8 are both switched to the opposite sides as shown in the drawing, the fluid pressure amplifying device 31 Is connected to the wheel cylinder 3, and the master cylinder 2 and the wheel cylinder 3
Is shut off, while the hydraulic pressure is supplied to the accumulator 7 to give the brake pedal 1 an appropriate operation feeling.

When the output port 15 and the hydraulic pressure supply port 13 are communicated as described above, the reaction chamber 1
8, the internal pressure rises and the reaction force pin 20 is urged together with the reaction force spring 21 so that the spool 1
6 is pressed toward the mover 23 side. Therefore, the spool 16
When the pressing force of the mover 23 is larger than the pressing force of the reaction force pin 20, the slider slides leftward in the figure, but slides rightward when smaller. When the spool 16 slides to the right,
The variable throttle s is closed and the hydraulic pressure supply port 1 of the output port 15 is closed.
3 is cut off, and further sliding to the right opens the variable throttle t to connect the output port 15 to the drain port 14. As a result, the hydraulic pressure acting on the reaction force chamber 18 also decreases. According to this operation, the spool 16 stops when the pressing force between the mover 23 and the reaction force pin 20 is finally balanced, and the hydraulic pressure at the output port 15 is reduced by the exciting current (the pressure of the master cylinder 2). ), And at the same time, the control hydraulic pressure acts on the wheel cylinder 3 to generate a predetermined braking force.

When the foot is released from the brake pedal 1 to release the braking from the braking state, a decrease in pressure is detected by the sensor 9, and the exciting current of the coil 24 is controlled by the control unit ECU 30 so that the movable element 23 Is moved rightward in FIG. 1, and the spool 16 is
Is moved to the right. Thereby, the variable aperture s
And the communication between the annular communication passage 16a and the hydraulic pressure supply port 13 is cut off. Further, when the spool 16 is moved to the right, the variable throttle t is opened to communicate the annular communication passage 16a with the drain port 14, and the brake fluid is supplied from the wheel cylinder 3 to the drain 4d via the hydraulic pressure amplifying device 31. Will be returned. At this time, the plunger body 34 of the hydraulic amplification device 31
Is pushed back to the input hydraulic chamber 33 by a compression spring provided in the output hydraulic chamber 35. Then, as described above, when the hydraulic pressure of the wheel cylinder 3 is reduced and the brake is released, and the decrease in the hydraulic pressure is detected by the sensor 10, the control device ECU 30 causes the hydraulic pressure passage opening / closing valve 2 to operate.
9 to close the hydraulic passage opening / closing valve 29,
The flow path between the external hydraulic pressure supply source 4 and the hydraulic pressure control valve 5 is shut off.

As described above, according to the brake fluid pressure control device of the above embodiment, the external fluid pressure supply source 4 and the fluid pressure control valve 5
Is provided with a hydraulic passage opening / closing valve 29 that communicates only when braking, so that the pressurized brake fluid is sent to the hydraulic pressure control valve 5 when braking is not performed. 5, a pressure drop in the accumulator 4b of the external hydraulic pressure supply source 4 due to leakage from the variable throttle s having a relatively weak sealing property can be prevented. That is, the external hydraulic pressure source 4
Loss in the pump 4
The operation frequency of “a” can be reduced. Further, since the hydraulic pressure amplifying device 31 is provided for mechanically further amplifying the hydraulic pressure of the brake fluid sent from the external hydraulic pressure supply source 4 via the hydraulic pressure control valve 5, the pressure in the external hydraulic pressure supply source 4 is increased. The amount of pressure can be reduced. Thus, the load on the pump 4a of the external hydraulic pressure supply source 4 can be reduced.

According to the brake fluid pressure control device, when the pressure from the output port 15 of the fluid pressure control valve 5 does not increase, a fail-safe operation state is established, and the switching valves 6 and 8 are provided with respective springs. Are returned to the state shown in the figure. In this state, the connection between the master cylinder 2 and the accumulator 7 is cut off, and the hydraulic pressure acts directly on the wheel cylinder 3, so that the rigidity of the hydraulic system from the master cylinder 2 to the wheel cylinder 3 does not decrease. Therefore, high brake responsiveness can be maintained.

The control unit ECU 30 determines the slip state of the wheel based on the detected data on the wheel rotational speed, and based on the determination result, determines whether the coil 24
The anti-skid control for increasing / decreasing the exciting current and the traction control can be performed.

In the above embodiment, the hydraulic pressure of the hydraulic control valve 5 is detected by detecting the hydraulic pressure of the master cylinder 2 by the sensor 9 and controlling the exciting current based on the detected data to move the spool 16. Is electrically controlled, but the hydraulic pressure may be controlled only by the physical action by moving the spool 16 by an actuator directly driven by the hydraulic pressure of the master cylinder 2.

In the above embodiment, the output port 1
The hydraulic pressure of the valve 5 is switched by directly acting on the switching valve 6 and the fail-safe valve 8, and when no hydraulic pressure is applied, the hydraulic pressure is automatically returned to a predetermined position by the action of a spring provided on each valve. However, it goes without saying that a system may be used in which the hydraulic pressure is detected by a sensor and the valve is electrically switched according to the detected hydraulic pressure. Further, in the above-described embodiment, the hydraulic pressure passage opening / closing valve 29 and the hydraulic pressure amplifying device 31 are provided, respectively. It goes without saying that the load on the pump 4a of the hydraulic pressure supply source 4 can be reduced.

Next, the control flow of the braking force distribution system provided in the above-described brake fluid pressure control device will be described with reference to flowcharts shown in FIGS.

First, a wheel speed sensor 4 provided for each wheel
The control device ECU 30 calculates each wheel speed based on the detection data from Step 4 (Step S1), filters the largest one of the obtained wheel speeds, and calculates the simulated vehicle speed (Step S1). S2). Then, the slip ratio of each wheel is calculated from the calculated simulated vehicle body speed and each wheel speed based on the following equation (step S3).

Slip ratio = [simulated vehicle speed−wheel speed] / simulated vehicle speed

After the slip ratio of each wheel is calculated, the difference between the front and rear wheels on the left and right sides of the vehicle is calculated based on the following equation (step S4).

Slip ratio difference = Front wheel slip ratio−Rear wheel slip ratio

Next, the control device ECU 30 determines whether or not the braking force distribution control is being performed based on the control flag X (step S5). Here, the control flag X
Is determined as being controlled, and when the flag X is being controlled, it is determined that the vehicle is not being controlled.

If it is determined that the braking force distribution control has not been performed, the slip ratio difference is compared with a predetermined value (step S6). The power distribution control is started, the control flag X is set to 1 (step S7), and the timer Y is operated from that time (step S8). Here, this timer Y
It is decremented for each control cycle. During operation, the timer Y is set to a predetermined time ty.

Then, the rear target wheel cylinder pressure at the start of the control is calculated according to the flowchart shown in FIG. 4 (step S9). First, the pressure increase speed of the master cylinder pressure is calculated based on the detection value of the sensor 9 (step S101). Next, the rear target wheel cylinder pressure at the start of the control is calculated based on the relationship between the master cylinder pressure increasing speed and the target wheel cylinder pressure set in advance as data (step S).
102).

Here, the concept of calculating the target wheel cylinder pressure in step S102 will be described. In this control, the braking force distribution of the front and rear wheels is controlled approximately to the broken line OAB 'so that the ideal distribution curve OAB as shown in FIG. 5 is obtained. Note that the straight OAD is a front and rear wheel 1: 1.
, That is, the master cylinder pressure is boosted to the front and rear wheels in the front and rear wheel 1: 1 distribution, and can be regarded as substantially proportional to the master cylinder pressure. Further, with respect to the rear wheel braking force, a region where the straight line OAD exceeds the ideal distribution curve OAB is a necessary control region of the braking force distribution system.

Based on these points, the relationship between “slow brake” in FIG. 6 and “fast brake” in FIG. 7 will be described. “Exceeding the threshold value” means that the straight line OA in FIG.
D (ie, master cylinder pressure) is the ideal distribution curve OAB
When the rear wheel braking force is larger than the rear wheel braking force, the value on the broken line OAB 'is set as the target wheel cylinder pressure of the rear wheel so as to approximate the rear wheel braking force to the ideal distribution curve OAB. It is. The “slow brake” and the “fast brake” are represented by a straight line O in FIG.
In relation to the control cycle on AD, for example, t0, t1, t2
Or t0 ', t1', t2 '
The difference between the wheel cylinder pressure of the rear wheel when it is determined that the control needs to be started and the target wheel cylinder pressure of the rear wheel at that time is different.

The present control is based on this. "Fast braking" means that the wheel cylinder pressure of the rear wheel when the necessity of the control start is determined and the target wheel cylinder pressure of the rear wheel at that time. 7, and as shown by a solid line (slip ratio difference B, rear W / C pressure B) in FIG.
Since the vehicle behavior is destabilized by the rapid pressure reduction control, the object is to eliminate the destabilization.

In steps S101 and S102, when "the slip ratio difference exceeds the control start threshold value" in FIGS. 6 and 7, the target wheel cylinder pressure of the rear wheel is immediately set to Pc in FIG. Instead of driving the brake fluid pressure control device, the target wheel cylinder pressure at the start of the control is set to be higher in order to gradually reduce the wheel cylinder pressure of the rear wheel to the target wheel cylinder pressure. That is, the chain line in FIG. 7 (slip ratio difference C, rear W / C pressure B)
As shown in FIG. 1, the pressure reduction is moderated to stabilize the behavior of the vehicle.

Next, the control unit ECU 30 determines whether or not the ABS control flag is set for each wheel, and if the ABS control flag is not set,
Based on the slip ratio of each wheel, it is determined whether or not each wheel has a tendency to lock. If it is determined that there is a tendency to lock, the ABS control flag is set to 1 and this tendency to lock is eliminated. Until the ABS control flag is reset to 0, target wheel cylinder pressures such as pressure reduction, holding, and pressure increase are set for each control cycle with respect to the current wheel cylinder pressure. On the other hand, when the ABS control flag is not set and the result of determining whether or not each wheel has a lock tendency based on the slip ratio of each wheel is not the ABS control, the ABS control is not performed. No target wheel cylinder pressure is set (step S1).
0).

Next, a target wheel cylinder pressure corresponding to a signal from the sensor 9 is calculated as normal booster control (step S11).

Then, only one of the target wheel cylinder pressure in the ABS control, the target wheel cylinder pressure in the braking force distribution control, and the target wheel cylinder pressure in the booster control is selected in consideration of the priority order. Thus, the brake fluid pressure control device is driven (step S12). Here, the priority order of these target wheel cylinder pressures is as follows: (ABS control)> (braking force distribution control)> (booster control).

Here, when the ABS control is not performed, the brake fluid pressure control device is driven by the target wheel cylinder pressure in the braking force distribution control. As a result, the target wheel cylinder pressure at the start of the braking force distribution control acts on the rear wheels.

Then, in the next control cycle, since the braking force distribution control is being performed, that is, the control flag X is set to 1, the process shifts to another control (step S5), and the timer Y is set to 0
If not (step S13), 1
(Step S14), and the target wheel cylinder pressure at the time when n time (n control cycles) has elapsed from the start of the braking force distribution control is calculated by, for example, the following formula (step S15).

Target wheel cylinder pressure = (target wheel cylinder pressure in current control cycle)-(predetermined value set in advance by the master cylinder pressure increasing speed)

However, this predetermined value is set in advance according to the speed at which the master cylinder pressure is increased.

Next, it is determined whether to terminate the braking force distribution control (step S16). Here, this determination is made for each control cycle based on whether or not the slip ratio difference is a predetermined value for determining the end (for example, 0 or less) and continues for a predetermined time. Next, the brake fluid pressure control device is driven to perform braking with the current target wheel cylinder pressure (step S12).

When the above control cycle is repeated and the timer Y becomes 0 (step S13), the target wheel cylinder pressure for performing the normal braking force distribution control is calculated (step S17). The brake fluid pressure control device is driven to perform braking by the pressure (step S12). Thereafter, when it is determined that the braking force distribution control is to be terminated because the slip ratio difference has continued for a predetermined time at the termination determination predetermined value, the control flag X is set to 0 (step S18) and the timer Y is reset to 0. (Step S19), the brake fluid pressure control device is driven to perform control using the normal target wheel cylinder pressure (Step S12), and the braking force distribution control is in a standby state until the slip ratio difference becomes a predetermined value or more again. Becomes

As described above, according to the above-described braking force distribution system, the front hydraulic pressure and the rear hydraulic pressure can be distributed very well, and thereby the behavior of the vehicle during braking can be improved. Can be stabilized. Also,
The braking force distribution device distributes the braking force without using expensive components such as a proportioning valve in the hydraulic circuit, so that the device can be simplified and the cost can be reduced. Further, since the target hydraulic pressure of the rear hydraulic pressure at the start of the braking force distribution control is reduced with time, it is possible to eliminate a sense of instability caused by a large hydraulic pressure fluctuation, and to further improve riding comfort. it can.

[0053]

As described above, according to the braking force distribution system of the present invention, the following effects can be obtained. According to the braking force distribution system according to the first aspect, the distribution of the front hydraulic pressure and the rear hydraulic pressure can be performed extremely well, whereby the behavior of the vehicle during braking can be satisfactorily stabilized. Further, since the braking force is distributed without using expensive components such as a proportioning valve in the hydraulic circuit, the device can be simplified and the cost can be reduced. Further, since the target hydraulic pressure of the rear hydraulic pressure at the start of the braking force distribution control is reduced with time, it is possible to eliminate a sense of instability caused by a large hydraulic pressure fluctuation, and to further improve riding comfort. it can.

[Brief description of the drawings]

FIG. 1 is a hydraulic system diagram of a brake hydraulic pressure control device illustrating an embodiment of a braking force distribution system according to the present invention.

FIG. 2 is a flowchart illustrating a flow of braking force distribution control for explaining an embodiment of the braking force distribution system of the present invention.

FIG. 3 is a flowchart illustrating a flow of braking force distribution control for explaining an embodiment of the braking force distribution system of the present invention.

FIG. 4 is a flowchart illustrating a flow of braking force distribution control for explaining an embodiment of the braking force distribution system of the present invention.

FIG. 5 is a graph illustrating an ideal distribution curve of braking force of front and rear wheels.

FIG. 6 is a graph showing changes in a rear wheel cylinder pressure and a slip ratio difference between front and rear wheels.

FIG. 7 is a graph showing changes in rear wheel cylinder pressure and a difference in slip ratio between front and rear wheels.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake pedal 2 master cylinder 3 wheel cylinder 4 external hydraulic pressure supply source 9 sensor 30 control unit ECU (controller)

Claims (1)

[Claims] 1. A master cylinder for generating a hydraulic pressure by operating a brake pedal, and a sensor for detecting the master cylinder pressure, wherein an external hydraulic pressure supply source is supplied to a wheel cylinder in accordance with a detection signal from the sensor. In the brake fluid pressure control device for applying the control fluid pressure, the control fluid pressure of the external fluid pressure supply source is adjusted so that the wheel cylinder pressure of the rear wheel gradually approaches the target wheel cylinder pressure in accordance with the speed at which the master cylinder pressure is increased. A braking force distribution system comprising a controller for controlling the braking force.