JPH10250563A - Brake hydraulic control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute the brake forces on the front wheels and on the rear wheels while carrying out the increase of the brake pressure. SOLUTION: In the cargo loading condition, a load detecting lever 23 is lowered relatively to an axle 24 so as to make the extension of a tensile spring 25 (the spring force) in the minimum value. As a result, since the force of a pressing member 26 to press a valve plunger 14' is made the minimum, the crossover points of a rear wheel side pressure intensifier valve 13' is made lower, the same as the crossover point of a front wheel side pressure intensifier valve 13. That is, the brake forces in the front and the rear wheels are distributed at the same value in the cargo loading condition. In the cargo unloaded condition, the load detecting laver 23 is raised relatively to the axle 24, so as to make the spring force of the tensile spring 25 are maximum. Consequently, since the force of the pressing member 26 to press the plunger 14' is made the maximum, the crossover point of the rear wheel side pressure intensifier valve 13' is made higher. That is, the brake force of the rear wheel is distributed smaller than the front wheel brake force in the unloaded condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a brake fluid pressure control device capable of obtaining a large brake pressure by increasing a fluid pressure generated by a master cylinder in an automobile, for example, and particularly, a large load. A brake fluid pressure control device that controls the increase in the rear wheel brake pressure due to the rear axle load that affects the front and rear wheels so that the braking force of the front and rear wheels is properly distributed between when the vehicle is empty and when the vehicle is loaded. It belongs to the technical field.

[0002]

2. Description of the Related Art Conventionally, for example, in an automobile, for example, a hydraulic brake system has generally been adopted in which hydraulic pressure generated in a master cylinder is introduced into a wheel cylinder to operate a brake. As one example of a conventional hydraulic brake system, for example, a hydraulic booster as shown in FIG. 10 boosts a pedaling force and outputs the boosted pressure, and the output is used to operate a master cylinder to generate a large brake pressure. There is a brake boost system. In the figure, 1 is a hydraulic brake booster, 2 is a brake pedal, 3 is a hydraulic booster, 4 is a pump, 5 is a motor M, 6 is an accumulator,
7 is a reservoir for a booster, 8 is a tandem master cylinder (hereinafter also referred to as MCY), 9 is a reservoir for MCY, 1
0,10 'is a wheel cylinder (hereinafter also referred to as W / C).

In such a hydraulic brake booster system 1, when the motor 5 is driven to operate the pump 4, the hydraulic fluid in the booster reservoir 7 is supplied to the hydraulic booster 3 and the accumulator. 6 and a predetermined hydraulic pressure is stored in the accumulator 6. In this state,
When the brake pedal 2 is depressed, the control valve (not shown) of the hydraulic booster 3 is switched, and the hydraulic pressure of the accumulator 6 is introduced into the power chamber (not shown) of the hydraulic booster 3 according to the pedaling force. The power piston (not shown) boosts the pedal effort by the hydraulic pressure introduced into the power chamber and outputs the boosted power. The output of the hydraulic booster 3 is used to output MCY8.
The MCY 8 generates a MCY pressure Pm by actuating a piston (corresponding to the hydraulic pressure generating device of the present invention).
m is supplied to the W / Cs 10, 10 'as brake fluid pressure to apply the brake. At this time, the pedaling force is boosted by the hydraulic booster 3, so that the braking force is large.

[0004] As another example of the conventional hydraulic brake system, there is a vacuum brake booster system for boosting and outputting a pedal depression force by a negative pressure as shown in FIG. 11, for example. In the figure, reference numeral 11 denotes a negative pressure brake booster, and 12 denotes a negative pressure booster. Since the negative pressure booster 12 is very well known, its detailed structure is not shown, but for example, refer to JP-A-2-164656.

[0005] Such a negative pressure brake booster system 11
In (2), the negative pressure booster 12 includes a diaphragm piston (not shown) that partitions a constant pressure chamber into which a negative pressure is always introduced and a variable pressure chamber. When the brake pedal 2 is depressed, a control valve (not shown) of the negative pressure booster 12 is switched, and the atmosphere is introduced into the variable pressure chamber according to the pedal depression force. The atmospheric pressure introduced into the transformer chamber causes the diaphragm piston to boost the pedal effort and output. Similarly, the piston of the MCY 8 is operated by the output of the negative pressure booster 12, and the MCY pressure Pm generated by the MCY 8 becomes W /
Supplied to C10, 10 'and braked.
At this time, the pedaling force is boosted by the negative pressure booster 12, so that the braking force is large.

The brake booster system employs various power sources such as a positive pressure air pressure or an electromagnetic force in addition to a hydraulic pressure and a negative pressure as a power source for the above-described boosting. There is a brake boost system. In addition, there are various types of boosters in a brake booster system using the same power source.

[0007]

In the brake boosting system such as the hydraulic brake boosting system 1 and the negative pressure brake boosting system 11 described above,
Boosters such as the hydraulic booster 3 and the negative pressure booster 12 are relatively large and expensive. The output of such a booster is limited by its capacity.
In order to increase the output of the booster beyond the limit, it is necessary to increase the capacity of the booster. However, if the capacity of the booster is increased, the booster becomes larger.

Therefore, as shown in FIG. 12A, for example, the MCY pressure Pm generated by the pedal depression force is increased without using the hydraulic booster 3 or the negative pressure booster 12 as described above. A brake boosting system that increases the braking force is conceivable.

As shown in FIG. 12A, in this brake booster system, a pressure increasing valve 13 is provided in a brake passage connecting the MCY 8 and the W / C 10. The pressure increasing valve 13 includes a valve plunger 14 having a valve portion 14a, a valve seat 15 formed of a rubber sheet on which the valve portion 14a can be seated, and a valve plunger 14 in a direction in which the valve portion 14a is separated from the valve seat 15. Spring 19 that constantly urges
And In this case, the effective pressure receiving area S1 of the seat portion of the valve plunger 14 when the valve portion 14a is seated on the valve seat 15 is larger than the cross-sectional area S2 of the portion (small diameter portion 14b) of the valve plunger 14 where pressure is not received (S1> S).
2) It is set. As the pressure increasing valve 13, a proportioning valve (P valve) which has been widely used in the past can be used in reverse. The P-valve is for reducing the rear wheel brake pressure when the brake pressure is equal to or higher than a predetermined pressure, thereby preventing the rear wheel from being locked early during braking. However, the pressure increasing valve is not limited to the P valve, and may have any structure as long as it has the above-described configuration.

The motor 16 is operated by the MCY.
Pump 1 for supplying the brake fluid to the W / C 10
7 bypasses the pressure-intensifying valve 13 and
3, and a pedal switch 18 for detecting depression of the brake pedal 2 is provided.

In this brake booster system, when the brake pedal 2 is depressed, the pedal switch 18
Detects this, the motor 16 is driven and the pressure increasing pump 17 is operated. As means for detecting a brake operation by depressing the brake pedal 2, there are various detection means other than the pedal switch 18, such as a pressure switch or pressure sensor for detecting the MCY pressure Pm, a stroke sensor for detecting the pedal stroke, and the like. .

When the brake pedal 2 is depressed, MC
Since the MCY pressure Pm is generated at Y8, the valve plunger 14 immediately strokes, and the valve portion 14a is seated on the valve seat 15. Then, the W / C pressure Pw is increased by the discharge pressure of the pressure increasing pump 17. And W / C pressure P
When w rises, the valve plunger 14 is pushed back to the left, and the valve portion 14a separates from the valve seat 15. As a result, the increased W / C pressure Pw escapes to the MCY 8 side and falls, so that the valve plunger 14 again strokes rightward, and the valve portion 14a is seated again on the valve seat 15 to balance. Thereafter, when the MCY pressure Pm rises, the W / C pressure Pw required to move the valve plunger 14 to the left and separate the valve portion 14a from the valve seat 15 is increased by the MCY pressure Pw.
It increases in accordance with the increase in the pressure Pm. Thus, the W / C pressure P
w is increased as the MCY pressure Pm increases. At this time, the MC on the input side of the pressure increasing valve 13
The relationship between the Y pressure Pm and the W / C pressure Pw on the output side is:

[0013]

(Equation 1)

Is given by

If the spring force SPG of the spring 19 is set to be extremely small, the term of the SPG in the equation (1) becomes almost zero, so that the pressure-intensifying valve 13 has an input / output characteristic as shown by a solid line in FIG. Will have.

As described above, according to the brake booster system shown in FIG. 12A, it is possible to increase the MCY pressure by the pedal depression force without using the hydraulic booster 3 or the negative pressure booster 12. It becomes possible.

Incidentally, in the pressure boosting valve 13 of such a brake booster system, the valve plunger 14
The spring force of the spring 19 that constantly urges the valve portion 14a in the direction away from the valve seat 15 applies the MCY pressure Pm to the MCY8.
Is set to be very weak so that the valve plunger 14 immediately strokes when pressure occurs, so that the pressure-intensifying valve 13 immediately increases the pressure of this input and outputs it as soon as there is an input.

However, in the brake booster system, the input / output characteristics of the pressure increasing valve 13 are as shown in FIG.
As shown in the above, the output is performed without increasing the pressure until the MCY pressure Pm reaches a predetermined level, and when the MCY pressure Pm is equal to or higher than the predetermined level, the break point is output while increasing the MCY pressure Pm. In some cases, input / output characteristics having a (pressure increase start point) are required. Therefore, the spring force of the spring 19 is M
Until the CY pressure Pm reaches the predetermined pressure, the valve plunger 1
By setting the size of the pressure increasing valve 4 so as not to make a stroke to the right, the pressure increasing valve 13 has such a configuration as shown in FIG.
The following input / output characteristics can be provided.

On the other hand, in an automobile, the rear wheel load is generally set to be larger than the front wheel load. Particularly, in a vehicle such as a bus or a truck in which the change in the loaded load is large, the rear wheel load is not available. It changes greatly between time and when loading. In addition, during braking, a moment is generated in the vehicle body in the direction in which the rear wheels are lifted, so that the contact pressure of the rear wheels decreases and the contact pressure of the front wheels increases. For this reason, if the front wheel braking force and the rear wheel braking force are equally distributed irrespective of the vehicle loading situation, the empty rear wheels tend to lock early. Therefore, conventionally, a P-valve is provided in the rear wheel brake system, and the MCY pressure P
In a region where the pressure m is equal to or higher than the predetermined pressure, the brake pressure of the rear wheels is reduced, and the braking forces of the front and rear wheels are appropriately distributed. In particular, a load sensing proportioning valve (hereinafter, referred to as LSPV), which is a P valve adapted to change the start of pressure reduction of the rear wheel brake pressure in accordance with the loaded load, is provided. The braking force of the front and rear wheels is appropriately distributed according to the loaded load.

From the above, the above-described pressure increasing valve 1
Also in the brake booster system using No. 3, the brake pressure is increased by controlling the brake pressure increase on the rear wheel brake system side and distributing the brake force of the front and rear wheels in the same manner as described above. Therefore, it is desired that the braking force of the front and rear wheels is appropriately distributed.

The present invention has been made in view of such circumstances, and an object of the present invention is to make it possible to increase the brake pressure and to appropriately distribute the braking force of the front and rear wheels. It is an object of the present invention to provide a brake fluid pressure control device that can perform the control.

[0022]

According to a first aspect of the present invention, there is provided a brake fluid pressure control device used in a two-system brake system. In addition, a pressure increase control device for the rear wheel brake pressure is provided, and the pressure increase characteristic of the pressure increase control device for the rear wheel brake pressure is at least partly increased by the pressure increase control device for the front wheel brake pressure. By setting the characteristics differently from the characteristics, the braking force of the front and rear wheels is appropriately distributed.

According to a second aspect of the present invention, the pressure increasing characteristic of the rear wheel brake pressure increasing control device is such that at least a part of the pressure increasing characteristic is controlled to increase the front wheel brake pressure according to the load of the vehicle. By setting the pressure increasing characteristic different from the pressure increasing characteristic of the device, the braking force of the front and rear wheels is appropriately distributed.

According to a third aspect of the present invention, a front wheel brake system for braking the front wheels by introducing the hydraulic pressure of the master cylinder to the front wheel brake cylinder and the hydraulic pressure of the master cylinder are introduced to the rear wheel brake cylinder. In a two-brake brake fluid pressure control system comprising a rear wheel brake system for applying a brake to a rear wheel, a front wheel side which increases the hydraulic pressure of the master cylinder to the front wheel brake system and outputs it to the front wheel side brake cylinder A pressure-intensifying valve is provided, and the front-wheel-side pressure-intensifying valve is used to derive an output port from which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a pressure-increasing pressure from a front-wheel-side hydraulic pressure source. When the hydraulic pressure of the master cylinder is smaller than a first predetermined pressure, the output port through which the hydraulic pressure is introduced is communicated with the input port and the output port to connect the output port to the front. The hydraulic pressure of a master cylinder is derived from the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, the pressure between the input port and the output port is shut off. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure by introducing the pressure-increasing hydraulic pressure to an output port, and A rear wheel-side pressure increasing valve that increases the hydraulic pressure of the master cylinder and outputs it to the rear wheel-side brake cylinder, and a break point that is a second predetermined pressure at which the rear wheel-side pressure increasing valve starts increasing the pressure. There is provided a load-response break point control means for performing change control in accordance with the load, and the rear wheel side pressure increasing valve derives an input port through which hydraulic pressure from the master cylinder is introduced, and an output hydraulic pressure. After and after An output port through which a pressure-increasing hydraulic pressure from the side pressure-increasing hydraulic pressure source is introduced, and a communication between the input port and the output port when the hydraulic pressure of the master cylinder is smaller than a second predetermined pressure; The hydraulic pressure of the master cylinder is derived from the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the second predetermined pressure, the pressure between the input port and the output port is shut off. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder by introducing the pressure-increasing hydraulic pressure to the output port as the output hydraulic pressure; The means is characterized in that the valve plunger is set so as to act on the valve plunger with a pressing force corresponding to the load of the vehicle so as to oppose the hydraulic pressure of the input port.

According to a fourth aspect of the present invention, a front wheel brake system for applying a brake to a front wheel by introducing a hydraulic pressure of a master cylinder to a front wheel brake cylinder and a hydraulic pressure of the master cylinder are introduced to a rear wheel brake cylinder. In a two-brake brake fluid pressure control system comprising a rear wheel brake system for applying a brake to a rear wheel, a front wheel side which increases the hydraulic pressure of the master cylinder to the front wheel brake system and outputs it to the front wheel side brake cylinder A pressure-intensifying valve is provided, and the front-wheel-side pressure-intensifying valve is used to derive an output port from which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a pressure-increasing pressure from a front-wheel-side hydraulic pressure source. When the hydraulic pressure of the master cylinder is smaller than a first predetermined pressure, the output port through which the hydraulic pressure is introduced is communicated with the input port and the output port to connect the output port to the front. The hydraulic pressure of a master cylinder is derived from the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, the pressure between the input port and the output port is shut off. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure by introducing the pressure-increasing hydraulic pressure to an output port, and A rear-wheel-side pressure-intensifying valve for increasing the hydraulic pressure of the master cylinder and outputting the pressure to the rear-wheel-side brake cylinder; and connecting the master cylinder and the rear-wheel-side brake cylinder through the rear-wheel-side pressure increasing valve. A bypass passage connecting the master cylinder and the rear wheel brake cylinder bypassing the rear wheel pressure increasing valve; and a bypass passage connecting the master cylinder and the rear wheel brake cylinder. A passage switching means for selectively connecting to a rear wheel-side brake cylinder via the pressure increasing valve side passage when the vehicle is loaded, and via the bypass passage when the vehicle is empty; A rear-wheel pressure-intensifying valve has an input port through which hydraulic pressure from the master cylinder is introduced, and an output port through which output hydraulic pressure is derived and pressure-increasing hydraulic pressure from the rear wheel-side hydraulic pressure source is introduced. And, when the hydraulic pressure of the master cylinder is smaller than a second predetermined pressure, communicating between the input port and the output port to derive the hydraulic pressure of the master cylinder as the output hydraulic pressure from the output port, The hydraulic pressure of the master cylinder is
When the pressure is equal to or higher than a predetermined pressure, the pressure between the input port and the output port is shut off, and the hydraulic pressure of the master cylinder is increased by introducing the pressure increasing hydraulic pressure to the output port. A valve plunger derived from the output port as a hydraulic pressure.

Further, according to a fifth aspect of the present invention, when the hydraulic pressure of the master cylinder reaches a third predetermined pressure in the bypass passage, the hydraulic pressure of the master cylinder is reduced and output to the rear wheel side brake cylinder. In addition, a proportioning valve is provided.

According to a sixth aspect of the present invention, in the bypass passage, the hydraulic pressure of the master cylinder at the break point where pressure increase starts with the same configuration as that of the rear wheel pressure intensifier valve is the break point of the rear wheel pressure intensifier valve. A second rear wheel side pressure increasing valve set to be higher than the hydraulic pressure of the master cylinder.

Further, the invention of claim 7 is characterized in that the pressure increasing gradient of the second rear wheel pressure increasing valve is set smaller than the pressure increasing gradient of the rear wheel pressure increasing valve.
The invention according to claim 8 is characterized in that the passage switching means includes an electromagnetic on-off valve.

According to a ninth aspect of the present invention, a front wheel brake system for braking the front wheels by introducing the hydraulic pressure of the master cylinder to the front wheel side brake cylinder and the hydraulic pressure of the master cylinder are introduced to the rear wheel side brake cylinder. In a two-brake brake fluid pressure control system comprising a rear wheel brake system for applying a brake to a rear wheel, a front wheel side which increases the hydraulic pressure of the master cylinder to the front wheel brake system and outputs it to the front wheel side brake cylinder A pressure-intensifying valve is provided, and the front-wheel-side pressure-intensifying valve is used to derive an output port from which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure and a pressure-increasing pressure from a front-wheel-side hydraulic pressure source. When the hydraulic pressure of the master cylinder is smaller than a first predetermined pressure, the output port through which the hydraulic pressure is introduced is communicated with the input port and the output port to connect the output port to the front. The hydraulic pressure of a master cylinder is derived from the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, the pressure between the input port and the output port is shut off. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure by introducing the pressure-increasing hydraulic pressure to an output port, and A rear-wheel-side pressure-intensifying valve that increases the hydraulic pressure of the master cylinder and outputs the pressure to the rear-wheel-side brake cylinder; and a turning point that is a second predetermined pressure at which the rear-wheel-side pressure-increasing valve starts increasing pressure. A deceleration response break point control means for performing change control according to the deceleration is provided, and the rear wheel side pressure increasing valve is configured to control an input port through which hydraulic pressure from the master cylinder is introduced, and an output hydraulic pressure. After derivation An output port through which a pressure-increasing hydraulic pressure from the side pressure-increasing hydraulic pressure source is introduced, and a communication between the input port and the output port when the hydraulic pressure of the master cylinder is smaller than a second predetermined pressure; The hydraulic pressure of the master cylinder is derived from the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the second predetermined pressure, the pressure between the input port and the output port is shut off. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder by introducing the pressure-increasing hydraulic pressure into the output port, as the output hydraulic pressure, and the deceleration response break point control. The means is set so as to control the start of pressure increase of the valve plunger in accordance with the deceleration of the vehicle.

Further, according to a tenth aspect of the present invention, the deceleration response break point control means detects a break point control piston for changing a break point at which the pressure increase of the valve plunger is started, and a predetermined deceleration of the vehicle. And a deceleration detecting means that operates and controls the break changing operation of the break control piston.

[0031] The invention according to claim 11 is characterized in that a breaking point which is the first predetermined pressure of the pressure increasing valve of the front wheel brake system,
When the vehicle is loaded, the second predetermined pressure of the pressure increasing valve of the rear wheel brake system is set to be equal.

[0032]

In the brake hydraulic pressure control apparatus according to the first aspect of the present invention, at least a part of the pressure increase characteristics of the rear wheel brake pressure increase control apparatus is a front wheel brake pressure increase control apparatus. Is set so as to be different from the pressure increasing characteristics, so that the braking forces of the front and rear wheels are appropriately distributed. In this way, in the first aspect of the present invention, by controlling the increase in the brake pressure of the rear wheel to be different from the increase in the brake pressure of the front wheel, the braking force of the front and rear wheels is appropriately distributed.

In particular, in the second aspect of the present invention, the brake pressure of the rear wheels is controlled to be different from the brake pressure of the front wheels in accordance with the load of the vehicle. Is more appropriately distributed according to the load of the vehicle.

Further, according to the third aspect of the invention, the start of pressure increase of the rear wheel pressure increasing valve of the rear wheel brake system is controlled by the load load response break point control means in accordance with the load of the vehicle. Become. Therefore, when the vehicle is empty,
By increasing the master cylinder pressure at the break point at the start of boosting of the rear wheel side booster valve from the break point of the front wheel side booster valve, the braking force of the rear wheel becomes smaller than the braking force of the front wheel when the vehicle is idle. , The braking force of the vehicle is distributed.
When the vehicle is empty, there is no load, so the rear wheels may lock earlier than the front wheels during braking.However, the braking force of the rear wheels is distributed so as to be smaller than the braking force of the front wheels. By doing so, early locking of the rear wheels is prevented, and the brakes of the vehicle can be more effectively applied according to the load of the vehicle.

When the vehicle is loaded, the break point of the rear wheel pressure intensifier valve is set near the break point of the front wheel pressure intensifier valve. , The braking force of the vehicle is distributed. When the vehicle is loaded, the loaded load is large, so there is almost no risk that the rear wheels will lock earlier than the front wheels during braking, and by distributing the braking forces of the front and rear wheels closer to each other, The brakes can be applied more effectively.

Further, in each of the fourth to eighth aspects of the present invention, when the vehicle is loaded, the pressure switching valve-side passage is selected by the passage switching means in the rear wheel brake system. Therefore, since the pressure increasing effect of the rear wheel pressure increasing valve is performed,
Similarly to the first aspect, the braking force of the vehicle is distributed such that the braking force of the rear wheels approaches the braking force of the front wheels. When the vehicle is idle, a bypass passage is selected by the passage switching means in the rear wheel brake system. Therefore, since the pressure increase of the rear wheel brake is not performed, the brake force of the vehicle is distributed such that the brake force of the rear wheel is smaller than the brake force of the front wheel, as in the first aspect of the invention. In particular, according to the third aspect of the invention, when the vehicle is idle, the braking force of the vehicle is distributed by the proportioning valve such that the braking force of the rear wheel is even smaller than the braking force of the front wheel. According to the fourth and fifth aspects of the present invention, when the vehicle is idle, the braking force of the vehicle is reduced by the second rear-wheel-side pressure-intensifying valve so that the braking force of the rear wheel is much smaller than the braking force of the front wheel. Distributed.

Further, in each of the ninth and tenth aspects of the present invention, the break point of the rear wheel pressure increasing valve of the rear wheel brake system is changed by the vehicle deceleration response break point control means in accordance with the deceleration of the vehicle. Become controlled. Then, when the deceleration of the vehicle reaches the predetermined deceleration while the hydraulic pressure of the master cylinder is small, the break point of the rear wheel side pressure increasing valve is set higher than the break point of the front wheel side pressure increasing valve. That is, when the deceleration of the vehicle reaches the predetermined deceleration while the hydraulic pressure of the master cylinder is small, the vehicle is idle, and therefore, when the vehicle is idle, the braking force of Is smaller than the braking force of the front wheels. Further, when the deceleration of the vehicle becomes a predetermined deceleration when the hydraulic pressure of the master cylinder becomes relatively large, the breaking point of the rear wheel side pressure increasing valve is made closer to the bending point of the front wheel side pressure increasing valve. That is, when the hydraulic pressure of the master cylinder increases and the deceleration of the vehicle reaches the predetermined deceleration, it is during loading of the vehicle. The braking force of the vehicle is distributed such that the braking force approaches the braking force of the front wheels.

Further, according to the eleventh aspect of the present invention, the break point of the front wheel side pressure intensifying valve is set to be equal to the break point of the rear wheel side pressure intensifying valve when the vehicle is loaded.
The braking forces of the front and rear wheels are equally distributed.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a negative pressure brake booster system to which a first embodiment of a brake hydraulic pressure control device according to the present invention is applied. Note that FIG.
1 and the same components as those of the brake system shown in FIG. 12 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

As shown in FIG. 1, the brake fluid pressure control device of the first embodiment is applied to a negative pressure brake boosting system 11 similar to that shown in FIG. The system 11 comprises two systems, a front wheel brake system A and a rear wheel brake system B.

In the front wheel brake system A, a pressure increasing valve 13, a pump driving motor 16, and a pressure increasing pump 17 are provided as in the brake boosting system shown in FIG. 12A, a valve plunger 14 having a valve portion 14a, a valve seat 15 on which the valve portion 14a can be seated, and the valve portion 14a having a valve seat 15 similar to the pressure booster valve 13 shown in FIG. And a spring 19 for constantly biasing the valve plunger 14 in a direction away from the user. The spring force of the spring 19 is as shown in FIG.
The input / output characteristics are set so as to have the same break points as shown in FIG. In this case, the pressure increasing valve 13
Is set at a position where the break point is lower than the input / output characteristics shown in FIG. Hereinafter, regarding the break point in the description of the present invention, a low position means that the break point is set at a position where the input is small, and a high position means that the break point is set at a position where the input is large. . Therefore, the pressure increasing valve 13 is set so that the pressure increasing starts with a relatively small input.

The pressure increasing valve 13 shown in FIG.
Similarly, when the valve portion 14a is seated on the valve seat 15, the effective pressure receiving area on the MCY8 side of the valve plunger 14 is S1.
And the area of the non-pressure receiving portion of the valve plunger 14 is set to a value S2 smaller than the pressure receiving area S1.

Further, the front wheel brake system A is provided with a hydraulic pressure sensor 20 for detecting the MCY pressure Pm, and this hydraulic pressure sensor 20 is electrically connected to an electronic control unit (ECU) 21. MCY pressure Pm from hydraulic pressure sensor 20
Is supplied to the ECU 21. Further, the ECU 21 is connected to the driving motor 16 of the pressure increasing pump 17, and when the MCY pressure Pm becomes close to the pressure at the break point of the pressure increasing valve 13 based on the detection signal from the hydraulic pressure sensor 20. , The operation of the driving motor 16, that is, the pressure increasing pump 17 is started.

On the other hand, the rear wheel brake system B is also provided with a pressure increasing valve 13 ', a pump driving motor 16', a pressure increasing pump 17 ', and a hydraulic pressure sensor 20' similar to the front wheel brake system A. ing. In the following description,
The components of the rear wheel brake system B that are the same as the components of the pressure boosting valve 13 of the front wheel brake system A will be described by adding the same reference numerals with “′”. Further, the pressure-intensifying valve 13 'of the rear wheel brake system B is provided with a load-response break point control mechanism 22 that detects a load and changes and controls a break point in accordance with the load.

This loading load response break point control mechanism 22
An L-shaped load detection lever 23 having one end 23a swingably locked to a housing 13c 'of the pressure increasing valve 13';
A tension spring 25 is provided between the other end 23b of the load detection lever 23 and the axle 24, and applies a pulling force that constantly pulls the load detection lever 23 downward in the figure, and is attached to one side of the load detection lever 23. A pressing member 26 arranged to apply a pressing force F to the valve plunger 14 'in a direction away from the valve seat 15', and a pressing member 26 which is always attached to the valve plunger 14 'in a direction separating the pressing member 26 from the valve plunger 14'. And a biasing spring 27.

Further, although not shown, a load sensor for detecting a load is provided, and a load detection signal from the load sensor is input to the ECU 21. The ECU 21 controls the operation of the booster pump 17 'of the rear wheel brake system B based on the detection signal from the load sensor and the detection signal from the hydraulic pressure sensor 20'. Note that the load sensor is not always necessary and can be omitted. In this case, the start of driving of the pressure boosting pump 17 'is adjusted to the time when the break point in the full vehicle state is the lowest, so that the booster valve 13' does not operate when the break point becomes high. , The pressure increasing pump 17 'is merely driven and the pump discharge liquid is merely circulated, and the pressure increasing effect is not performed. However, when this load sensor is provided, the pressure-intensifying pump 17 'can be driven only when necessary, which is effective in terms of energy saving.

The booster valves 1313 'of the front and rear wheel brake systems A and B are both mounted on a chassis (not shown). Therefore, when the distance between the chassis and the axle changes according to the load, the amount of extension of the tension spring 25 changes. That is, the tensile force of the tension spring 25 changes according to the load, and the pressing force F with which the pressing member 26 presses the valve plunger 14 ′ changes according to the load. When the vehicle is fully loaded, the rear wheel brake system B is set so that the break point of the pressure boost valve 13 'of the rear wheel brake system B is the same as the break point of the pressure boost valve 13 of the front wheel brake system A. Spring 1 of pressure increasing valve 13 '
The spring force of the spring 9 and the spring force of the tension spring 25 and the spring 27 of the loading load response break point control mechanism 22 are set. Note that, in this example, the booster valve 1
Although the break points of 3, 13 'are set to be the same in the front and rear wheel brake systems A, B, it is needless to say that the break points are not necessarily limited to these and may be different from each other. Other configurations of the negative pressure brake booster system 11 in this example are the same as those in FIGS. 11 and 12.

Next, the pressure increasing valve 1 thus configured
Negative pressure brake booster system 1 including a hydraulic pressure control device composed of 3, 13 'and a load-response break point control mechanism 22
1 will be described.

When the vehicle is fully loaded and the brakes are not operated,
Both pressure-intensifying valves 1313 'and the load-load-response break point control mechanism 22 are in the states shown in the drawings. That is, the valve portions 14a, 14a 'of the two booster valves 13, 13'.
Is separated from the valve seats 15 and 15 ', and the input ports 13a and 13
a 'is in communication with the output ports 13b, 13b'. In addition, since the loaded load is maximized, the chassis relatively descends toward the axle 24, and the extension of the tension spring 25 is minimized. Therefore, the tension force by which the tension spring 25 pulls the load detection lever 23 is also minimized. I have.

In this state, when the brake pedal 2 is depressed and the normal brake operation is performed, the control valve (not shown) of the negative pressure booster 12 is switched, similarly to the conventional negative pressure brake booster system. As a result, the negative pressure booster 12 is activated to generate an output of a magnitude obtained by boosting the pedal depression force, and the output of the negative pressure booster 12 activates the piston (not shown) of the MCY 8 to cause the MCY 8 to operate. Generates the MCY pressure Pm, and the hydraulic fluid of the MCY pressure Pm is introduced into the input ports 13a of the pressure increasing valves 13 of both brake systems.

Further, the hydraulic fluid introduced into each of the input ports 13a, 13a 'is supplied to the valve portions 14a, 14a' and the valve seat 15,
It flows out of each output port 13b, 13b 'through a gap with 15', and flows into each W / C 10, 10 '. In this way, the MCY pressure Pm becomes the W / C1
The normal service brake is applied to both the front and rear wheels. In this case, the pedaling force is boosted by the vacuum booster 12, so that the braking force is large.

At this time, the output ports 13b, 13b '
The W / C pressures Pw, which are the output pressures from, are not controlled at all by the pressure-intensifying valves 13 and 13 ', and become the same as the MCY pressure Pm. That is, the W / C pressures Pw of the front and rear wheels are the same as the MCY pressure Pm and increase with the increase of the MCY pressure Pm, and the input / output characteristics of the pressure intensifying valves 13 and 13 ′ from the origin O as shown in FIG. The characteristics are along the straight line a having a 45-degree inclination.

Further, the MCY pressure Pm is set to
The direction in which the valve portions 14a, 14a 'are respectively seated on the valve seats 15, 15' on the valve plungers 14, 14 'of 3, 13',
That is, they act in a direction against the spring force of the springs 19 and 19 ', and the force is given by Pm × S2. However, in the front wheel brake system A, the force Pm × S2 acting on the valve plunger 14 is
In the range of the MCY pressure Pm smaller than the spring force, the valve plunger 14 does not move downward in FIG. In the rear wheel brake system B, the force Pm × S2 acting on the valve plunger 14 'is
In the range of the MCY pressure Pm smaller than the resultant force of the spring force of 9 'and the pressing force F of the pressing member 26, the valve plunger 14'
Does not move upward in FIG.

Similarly, when the MCY pressure Pm is in this range, the ECU 21 operates based on the detection signal of the MCY pressure Pm from the hydraulic pressure sensors 20 and 20 '.
7 'does not work. Therefore, the pressure increasing valves 13, 1
3 'does not increase the pressure. When the brake pedal 2 is released in this range of the MCY pressure Pm, the W / C pressure Pw becomes M
As the CY pressure Pm drops, it drops along the straight line a, and the brake is released.

In the front wheel brake system A, the MCY pressure P
m rises and the MCY pressure Pm falls within a range where the force Pm × S2 acting on the valve plunger 14 is larger than the spring force of the spring 19, the valve plunger 14 resists the spring force of the spring 19, as shown in FIG. Move downward, the valve portion 14a is seated on the valve seat 15, and the input port 13a
And the output port 13b are shut off. Also, the MCY at this time
At the pressure Pm, also in the rear wheel brake system B, the valve plunger 14 'moves upward in FIG. 1 against the resultant force of the spring force of the spring 19' and the pressing force F of the pressing member 26, and the valve portion 14a ' Is seated on the valve seat 15 'and the input port 1
3a 'and the output port 13b' are cut off.

On the other hand, when the MCY pressure Pm is
When the pressure near the pressure for moving the 4,14 'is reached, the ECU 21
Operates the pressure-increasing pumps 17, 17 'based on the detection signal of the MCY pressure Pm from the hydraulic pressure sensors 20, 20'.
Thereby, the pressure increasing valve 13 shown in FIG.
As in the case of the booster pump 17, each booster pump 1
The discharge liquids 7, 17 'are supplied to the respective W / Cs 10, 10', respectively, and are supplied to output ports 13b, 13b 'of the pressure increase valves 13, 13', respectively.
Performs a pressure increasing action. That is, the pressure increasing valves 13, 13 '
In FIG. 2, the input / output characteristic is a characteristic along a line c having a pressure increasing gradient larger than the inclination of the line a from the break point b. At this time, the relationship between the MCY pressure Pm and the W / C pressure Pw is given by the above-described formula 1 in the front wheel brake system A, and in the rear wheel brake system B,

[0057]

(Equation 2)

Is given by Although the constant terms seem to be different between Equation 1 and Equation 2, as described above, when the vehicle is in a fully loaded state, the booster valve 1 of the rear wheel brake system B
The break point 3 'is the pressure increasing valve 13 of the front wheel brake system A.
Is set to be the same as the break point of the front wheel brake system A, and the combined force of the spring force of the spring 19 of the front wheel brake system A, the spring force of the spring 19 ′ of the rear wheel brake system B, and the pressing force F of the pressing member 26. Therefore, both constant terms of Expressions 1 and 2 are equal to each other, and Expressions 1 and 2 are the same.

Due to the pressure-intensifying action of these pressure-increasing valves 13 and 13 ′, the negative-pressure brake booster system 11 causes the pressure-intensifying action of the pressure-intensifying valves 13 and 13 ′ to increase the boosting action of the negative-pressure booster 12. Is added, so both front and rear wheels have large W / C pressure Pw
And the braking force becomes extremely large. As a result, the brake of the fully loaded vehicle is reliably applied.

When the brake pedal 2 is released in this range of the MCY pressure Pm, the W / C pressure Pw drops along the straight line c, the break point b, and the straight line a with the drop of the MCY pressure Pm, and the brake is released. I do.

On the other hand, when the vehicle is idle and the brakes are not operated, the pressure increasing valve 13 of the front wheel brake system A is the same as that of the full load vehicle, but the pressure increasing valve 1 of the rear wheel brake system B is not used.
3 'is different from the full car state. In other words, when the vehicle is empty, there is no load, so the chassis of the vehicle is
Relative to the pressure increase valve 1
3 'and the load detection lever 23 and the pressing member 26 of the loading load response break point control mechanism 22 also move relatively upward with respect to the axle 24, and the extension of the extension spring 25 is maximized. Power is also maximum. Therefore, the pressing force F of the pressing member 26 is also maximum.

When the brake pedal 2 is depressed in this state, in the front wheel brake system A, the pressure increasing valve 1
3 operates in the same manner as in the above-described full vehicle condition, so that the W / C pressure Pw of the front wheel brake system A increases along the straight line a, the break point b, and the straight line c shown in FIG. I do. On the other hand, in the rear wheel brake system B, a pressing force F by which the pressing member 26 presses the valve plunger 14 ′.
Is maximized, the valve plunger 14 'of the pressure-intensifying valve 13' does not move upward even if the MCY pressure Pm exceeds the break point b. That is, the pressure increasing valve 13 'of the rear wheel brake system B has not yet performed the pressure increasing operation, and the W / C pressure Pw of the rear wheel brake system B is equal to the MCY pressure Pm.
Along with the straight line a shown in FIG. 2 without increasing the pressure.

When the MCY pressure Pm rises, the force for pushing the valve plunger 14 'of the pressure increasing valve 13' of the rear wheel brake system B upward is caused by the spring force of the spring 19 'and the pressing member 26.
Exceeds the resultant force with the pressing force F, the valve plunger 14 'moves upward against the resultant force, and the valve portion 14a'
Is seated on the valve seat 15 ′, and the input port 13 a ′ and the output port 13
b 'is cut off. The ECU 21 receives the detection signal from the hydraulic pressure sensor 20 'and the detection signal from the load sensor.
Operates the pressure increasing pump 17 ', so that the pressure increasing valve 1
3 'performs a pressure increasing action. That is, the input / output characteristic of the pressure increasing valve 13 'is a characteristic along a straight line e having the same pressure increasing gradient as the straight line c from the break point d in FIG.

At this time, the relationship between the MCY pressure Pm and the W / C pressure Pw is given by the above-described formula 1 in the front wheel brake system A, and by the formula 2 in the rear wheel brake system B. In the case of the empty vehicle, since the pressing force F of the pressing member 26 in the constant term of Expression 2 is large, both constant terms of Expression 1 and Expression 2 are different from each other. Also, when the brake is released, the W / C pressure Pw of the rear wheel brake system B falls along exactly the opposite direction as when the brake was released.

Further, when the vehicle is in a loaded state between the empty state and the full state, the pressing member 26 presses the valve plunger 14 'in the pressure increasing valve 13' of the rear wheel brake system B as described above. Since the pressing force F changes in accordance with the loading situation, the W / C pressure Pw of the rear wheel brake system B becomes MCY
As the pressure Pm rises, a straight line a and a break point b in FIG.
And the break point f between the break point d and the straight line g having the same pressure increasing gradient as the straight lines c and e. Also, when the brake is released, the W / C pressure Pw of the rear wheel brake system B falls along exactly the opposite direction as when the brake was released. On the other hand, the W / C pressure Pw of the front wheel brake system A rises along the straight line a, the break point b, and the straight line c as described above because the input / output characteristics of the pressure increasing valve 13 are not affected by the loaded state of the vehicle. I do.

As described above, according to the negative pressure brake booster system 11 of the first example, when the vehicle is in a full load state, both the pressure increasing valves 13 and 13 'of the front and rear wheel brake systems perform the same operation. Therefore, the W / C pressure Pw of both brake systems is
Increase or decrease in exactly the same way. That is, when the vehicle is fully loaded, the braking forces of the front and rear wheels are equally distributed. In the fully loaded state of this vehicle, since the loaded load is extremely large, there is almost no possibility that the rear wheels lock earlier than the front wheels during braking, and thus, by equally distributing the braking forces of the front and rear wheels, The vehicle can be more effectively braked.

Further, in a state other than the full load state of the vehicle,
Since the booster valves 13 and 13 'of the front and rear wheel brake systems operate differently from each other, the W / C pressure Pw of the rear wheel brake system B becomes higher than the W / C pressure Pw of the front wheel brake system A in a range exceeding the predetermined MCY pressure Pm. / C pressure Pw. That is, in a state other than the full-vehicle state of the vehicle, the braking force of the vehicle is distributed such that the braking force of the rear wheels is smaller than the braking force of the front wheels. In a state other than the full-vehicle state of the vehicle, the loaded load is not so large, and the rear wheels may lock earlier than the front wheels during braking,
By distributing the braking force of the rear wheels so as to be smaller than the braking force of the front wheels in this way, it is possible to prevent early locking of the rear wheels, and to more effectively apply the brake of the vehicle according to the load of the vehicle. Can be used.

FIG. 3 is a view similar to FIG. 1, showing a negative pressure brake booster system having a second embodiment of the brake fluid pressure control device according to the present invention. The same components as those in the negative pressure brake booster system of the first example shown in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 3, the negative pressure brake booster system 11 of the second embodiment is different from the negative pressure brake booster system 11 of the first embodiment shown in FIG. The load-load-response break point control mechanism 22 provided at 13 'is deleted, and the hydraulic pressure sensor 20' of the rear wheel brake system B is also deleted. In the rear wheel brake system B, there is provided a bypass passage 28 for directly connecting the MCY 8 and the W / C 10 'by bypassing the pressure increasing valve 13'.

Further, an electromagnetic switching valve 30 is provided in a passage 29 connecting the MCY 8 and the input port 13a 'of the pressure increasing valve 13'. The solenoid on-off valve 30 is set with a shut-off position I that shuts off the passage 29 and a communication position II that communicates with the passage 29, and is a normally closed valve that is normally set to the shut-off position I. An electromagnetic opening / closing valve 31 is provided in the bypass passage 28. The electromagnetic opening / closing valve 31 has a communication position I for communicating with the bypass passage 28 and a shutoff position II for shutting off the bypass passage 28. Normally, the valve is normally opened at the communication position I. These first
The second solenoid on-off valve and the second solenoid on-off valve are both connected to the ECU 21, and the opening and closing of these are controlled by the ECU 21. Other configurations of the negative pressure brake booster system 11 of the second example are the same as those of the negative pressure brake booster system 11 of the first example.

In the negative pressure brake booster system 11 of the second example configured as described above, the pressure increasing valve 13 of the front wheel brake system A operates the front wheel brake in the aforementioned first example regardless of the loaded state of the vehicle. It performs exactly the same operation as the pressure increasing valve 13 of the system A. Therefore, the W / C pressure Pw of the front wheel brake system A increases and decreases along a straight line a having a 45-degree slope, a break point b, and a straight line c having a pressure increasing gradient as shown in FIG.

On the other hand, in the rear wheel brake system B, first, when the vehicle is idle, the ECU 21 moves the first solenoid on-off valve 30 to the shut-off position I as shown in FIG. The electromagnetic on-off valve 31 is set to the communication position I. Therefore, W of the rear wheel brake system B
/ C10 'directly communicates with the MCY8 without the intermediary of the pressure increasing valve 13'.

In this state, when the brake pedal 2 is depressed and the MCY pressure Pm is generated, the MCY pressure Pm becomes W /
It is directly introduced into C10 'without increasing or decreasing the pressure. That is, the W / C pressure Pw of the rear wheel brake system B increases or decreases along the straight line a as shown in FIG. Therefore, also in the negative pressure brake booster system 11 of the second example, when the vehicle is empty, the W / C pressure Pw of the rear wheel brake system B in the range exceeding the break point b of the MCY pressure Pm.
Is smaller than the W / C pressure Pw of the front wheel brake system A. That is, when the vehicle is idle, the braking force of the vehicle is distributed such that the braking force of the rear wheels is smaller than the braking force of the front wheels.

When the vehicle is loaded, the ECU 21 sets the first solenoid on-off valve 30 to the communication position II and sets the second solenoid on-off valve 31 to the shut-off position II according to the detection signal from the load sensor. Therefore, W of the rear wheel brake system B
/ C10 'communicates with MCY8 via a pressure-intensifying valve 13'. This pressure-intensifying valve 13 'is provided with a front wheel brake system A
, The W / C pressure Pw of the rear wheel brake system B follows the straight line a, the break point b, and the straight line c just like the front wheel brake system A. Will increase or decrease. That is, in the loaded state of the vehicle, the braking force of the vehicle is distributed such that the braking force of the rear wheels is exactly equal to the braking force of the front wheels.

In this example, the pressure increasing characteristics of the front and rear wheels are exactly the same in the loaded state. However, the present invention is not necessarily limited to this. It can be set as follows. Other operations and effects of the negative pressure brake booster system 11 of the second example are the same as those of the first example.

FIG. 5 is a view similar to FIG. 3 showing a negative pressure brake booster system having a third embodiment of the brake fluid pressure control device according to the present invention. Note that the same components as those of the negative pressure brake booster system of the second example shown in FIG. 3 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 5, the negative pressure brake booster system 11 of the third example is different from the negative pressure brake booster system 11 of the second example shown in FIG. P valve 32 on the W / C 10 'side from
Are arranged. This P valve 32 is a pressure increasing valve 1
3 and 13 ', the components of which are described in correspondence with the components of the pressure-intensifying valve 13. The valve plunger 33 is
The valve portion 33a is in the valve portion 14a, the small diameter portion 33b is in the small diameter portion 14b, the valve seat 34 is in the valve seat 15, the spring 35 is in the spring 19, the pressure receiving area S3 is in the pressure receiving area S1, and the cross-sectional area S2 is in section. Each corresponds to the area S4. Also, P
The input and output ports of the valve 32 are opposite to those of the pressure increasing valve 13. That is, the input port 3 of the P valve 32
2a is closer to the small diameter portion 33b than the valve seat 34, and the input port 32a is connected to the MCY 8 via the second electromagnetic on-off valve 31. The output port 32b of the P valve 32 is located closer to the valve portion 33a than the valve seat 34,
The output port 32b is connected to the W / C 10 '. Then, the set spring force of each area S3, S4 of the P-valve 32 and the spring 35 becomes the pressure at the break point h at which the MCY pressure Pm is a predetermined pressure larger than the pressure at the break point b in FIG. The valve plunger 33 is set to start moving. Other configurations of the negative pressure brake booster system of the third example are the same as those of the second example.

In the negative pressure brake booster system 11 of the third example configured as described above, the front wheel brake system A and the rear wheel brake system B when loading are operated in exactly the same manner as in the second example. That is, in the front wheel brake system A, the W / C pressure Pw increases and decreases along the straight line a, the break point b, and the straight line c regardless of the loaded state of the vehicle in FIG. In addition, the rear wheel brake system B when loading the vehicle is provided with the first solenoid on-off valve 3
0 is in the communication position II, and the second solenoid valve 31 is in the shut-off position.
Since they are set to I, respectively, the W / C pressure Pw similarly increases and decreases along the straight line a, the break point b, and the straight line c. Therefore, in the loaded state of the vehicle, the braking force of the vehicle is distributed such that the braking force of the rear wheel is exactly equal to the braking force of the front wheel. It should be noted that the pressure increasing characteristics of the front and rear wheels may be set differently when the vehicle is loaded.

On the other hand, in the rear wheel brake system B when the vehicle is empty, the first solenoid valve 30 is set to the shut-off position I and the second solenoid valve 31 is set to the communication position I.
And the W / C 10 ′ are connected via the P valve 32. Accordingly, in the range of the MCY pressure Pm up to the break point h where the valve plunger 33 of the P valve 32 starts to move, the W / C pressure Pw increases and decreases along the straight line a, and in the range of the MCY pressure Pm exceeding the break point h. , W / C pressure Pw increases and decreases along a straight line i having a pressure reduction gradient smaller than the gradient of the straight line a. At this time, the MCY pressure Pm and the W / C pressure P
The relationship with w

[0080]

(Equation 3)

Is given by Therefore, in the third example, when the vehicle is idle, the braking force of the vehicle is distributed such that the braking force of the rear wheel is much smaller than the braking force of the front wheel as compared with the second example. Other operational effects of the negative pressure brake booster system 11 of the third example are the same as those of the second example.

FIG. 6 is a view similar to FIG. 5, showing a negative pressure brake booster system having a fourth embodiment of the brake fluid pressure control device according to the present invention. The same components as those of the negative pressure brake booster system of the third example shown in FIG. 5 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, the negative pressure brake booster system 11 of the fourth embodiment is similar to the negative valve brake booster system 11 of the third embodiment shown in FIG. 32, the second pressure increasing valve 3
6 is provided in the bypass passage 28. The second pressure-intensifying valve 36 has exactly the same configuration as the pressure-increasing valve 13 '. The components of the second pressure-increasing valve 13' will be described in correspondence with the components of the pressure-increasing valve 13 '.
Is the valve plunger 14 ', and the valve portion 37a is the valve portion 14
a, the small diameter portion 37b corresponds to the small diameter portion 14b ', the valve seat 38 corresponds to the valve seat 15', and the spring 39 corresponds to the spring 19 '. The pressure receiving area of the valve portion 37a and the sectional area of the small diameter portion 37b are the same as those of the pressure increasing valve 13 ', and are set to S1 and S2, respectively. Also,
The set spring force of the spring 39 of the second pressure increasing valve 36 is set to be larger than the set spring force of the spring 19 'of the pressure increasing valve 13'. Therefore, the break point of the second pressure increasing valve 36 is, as shown in FIG.
The break point j is located at a position higher than the break point b of 3 '.

Negative pressure brake booster system 1 of the fourth example
The other configuration of 1 is the same as that of the third example.

In the negative pressure brake booster system 11 of the fourth example configured as described above, the front wheel brake system A and the rear wheel brake system B when loading are operated in exactly the same manner as the second and third examples. In FIG. 7, each W / C pressure P
w increases and decreases along a straight line a, a break point b, and a straight line c. Therefore, in the loaded state of the vehicle, the braking force of the vehicle is distributed such that the braking force of the rear wheel is exactly equal to the braking force of the front wheel.

On the other hand, in the rear wheel brake system B when the vehicle is empty, the first solenoid on-off valve 30 is in the shut-off position as in the second and third examples.
I and the second electromagnetic on-off valve 31 are set at the communication position I, respectively, so that the MCY 8 and the W / C 10 ′ are connected via the second pressure increasing valve 36. Therefore, in the range of the MCY pressure Pm up to the break point j at which the valve plunger 37 of the second pressure increasing valve 36 starts moving, W
The / C pressure Pw increases and decreases along the straight line a, and in the range of the MCY pressure Pm exceeding the break point j, the W / C pressure Pw increases and decreases along the straight line k having the same pressure increasing gradient as the straight line c. At this time, the relationship between the MCY pressure Pm and the W / C pressure Pw is:

[0087]

(Equation 4)

Is given by Therefore, when the vehicle is empty, the braking force of the vehicle is distributed such that the braking force of the rear wheels is smaller than the braking force of the front wheels.

The valve portion 37a of the second pressure increasing valve 36
Assuming that the pressure receiving area is S5 different from S1 and the sectional area of the small diameter portion 37b is S6 different from S2, the second pressure increasing valve 3
6 can be different from the pressure increasing gradient of the pressure increasing valve 13 '. In that case, S5-S6 = S1-S2, and [S5 / (S5-S6) <S1 / (S1-S
2)], as shown in FIG. 7, the characteristic is along a straight line k 'having a pressure increasing gradient smaller than the pressure increasing gradient of the straight line k at the same break point j as shown in FIG. In this way, the braking force of the vehicle is distributed such that the braking force of the rear wheel is even smaller than the braking force of the front wheel. (If the above inequality is reversed, the pressure increase of the straight line k ' It goes without saying that the gradient is larger than the pressure increasing gradient of the straight line k).

Further, although not shown, a predetermined number of bypass passages similar to the bypass passage 28 are provided in parallel with the bypass passage 28, and these bypass passages are provided with the same electromagnetic on / off valves as the second electromagnetic on / off valve 31, respectively. The pressure intensifier valves have the same structure as the second pressure intensifier valve 36, and have different break points and the same or different pressure intensification gradients. These solenoid on / off valves are individually opened and closed by the ECU 21 according to the load. By controlling, various characteristics such as a break point m and straight lines n and n 'can be obtained as shown in FIG. Other functions and effects of the negative pressure brake booster system 11 of the fourth example are the same as those of the third example.

FIG. 8 is a diagram partially showing a negative pressure brake booster system having a fifth embodiment of the brake fluid pressure control device according to the present invention. The same components as those in the negative pressure brake booster system of the first example shown in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the first example shown in FIG. 1 described above, there is provided a load-response break point control mechanism 22 for changing the break point of the pressure-intensifying valve 13 'of the rear wheel brake system B in accordance with the load. However, in the negative pressure brake booster system 11 of the fifth example, the loading load response break point control mechanism 22
Instead, as shown in FIG. 8, a deceleration response break point control mechanism 40 for changing and controlling the break point of the pressure increasing valve 13 'of the rear wheel brake system B according to the vehicle deceleration is provided.

The deceleration response break point control mechanism 40 includes a break point control piston 41 for pressing the valve plunger 14 'of the pressure increasing valve 13', and a break point control piston 41.
And a deceleration detection valve 42 (hereinafter, also referred to as a G valve) that controls the hydraulic pressure acting on the valve according to the deceleration.

The spring force of the spring 43 is applied to one surface 41a of the break point control piston 41.
In the direction of the valve plunger 14 '. In this case, a spring 44 is contracted between the valve plunger 14 'and the break point control piston 41, and the spring force of the spring 44 acts on the valve plunger 14 in the same direction as the spring 19'. . Further, a chamber 45 is provided on the other surface 41b side of the break point control piston 41, and this chamber 45 can communicate with the output port 13b 'of the pressure increasing valve 13'. That is, the other surface 41b of the break point control piston 41 has W /
The C pressure Pw is applied in a direction to separate the break point control piston 41 from the valve plunger 14 '.

By controlling the set length L of the spring 44 according to the position of the break point control piston 41, the spring force of the spring 44 acting on the plunger 14 'is controlled, and the break point of the pressure increasing valve 13' is controlled. Is controlled to change.

In this case, the set spring force of each of the springs 19 'and 44 is such that the MCY pressure Pm at which the valve plunger 14' of the pressure-intensifying valve 13 'starts moving when the vehicle is loaded is:
The valve plunger 14 of the pressure-intensifying valve 13 of the front wheel brake system A is set to be equal to the MCY pressure Pm at which movement is started (note that, without being limited to this, the two MCY pressures Pm may be different. Needless to say).

On the other hand, the G valve 42 is disposed in a passage 46 between the output port 13b 'and the chamber 45, and when the vehicle deceleration exceeds a predetermined deceleration, the inertia ball ( The G ball 47 is formed of a valve seat 48 on which the G ball 47 can be seated. Normally, the G ball 47 is set so as to be separated from the valve seat 48 and communicate with the passage 46, and when the vehicle is decelerated at a predetermined deceleration or more, the G ball 47 moves and sits on the valve seat 48, The passage 46 is shut off.

In this case, the predetermined deceleration at which the G ball 47 starts to move is M within a range not exceeding the MCY pressure Pm at the break point b (shown in FIG. 9) of the pressure increasing valve 13 'when the vehicle is loaded.
The deceleration is set to a magnitude generated by the CY pressure Pm. In this example, the predetermined deceleration is set in this way so that the braking forces of the front and rear wheels are equally distributed when the vehicle is loaded, but the braking forces of the front and rear wheels are different when the vehicle is loaded. The allocation is not limited to this. Other configurations of the negative pressure brake booster system 11 of the fifth example are the same as those of the first example.

In the negative pressure brake booster system 11 of the fifth example configured as described above, the front wheel brake system A operates in exactly the same manner as in the first example, and the W / C pressure Pw of the front wheel brake in FIG. Increases or decreases along a straight line a, a break point b, and a straight line c regardless of the loaded state of the vehicle.

On the other hand, the rear wheel brake system B has the following pressure increasing characteristics. When the vehicle is loaded, the same MCY pressure P is applied when the brakes are applied as compared to when the vehicle is empty.
Even at m, the vehicle deceleration is small. Therefore, when loading,
While the MCY pressure Pm is relatively small, the G ball 47 does not move and the chamber 45 is not sealed, but a predetermined deceleration occurs in the vehicle at the MCY pressure Pm before the MCY pressure Pm becomes the pressure at the break point b. Then, the G ball 47 moves and sits on the valve seat 48. Then, the passage 46 is shut off and the chamber 45 is sealed,
The MCY pressure Pm at that time is sealed in the chamber 45, and the break point control piston 41 is fixed at the position at that time. When loading, the G ball 47 starts moving M
Since the CY pressure Pm is larger than when the vehicle is empty, the fixed position of the break point control piston 41 is the rightmost position in FIG.

Accordingly, the set length L of the spring 44 for pressing the valve plunger 14 'of the pressure increasing valve 13' in the rear wheel brake system B when the vehicle is loaded is determined by this fixed position of the break point control piston 41. . In this case, since the break point control piston 41 is fixed at the rightmost position, the set length L of the spring 44 during loading is the longest. In other words, the spring 44
, The set spring force at the time of loading is determined to be the minimum, and the breaking point of the pressure increasing valve 13 ′ at the time of loading is at a low position. In that case,
As described above, the resultant force of the set spring force of the spring 44 and the set spring force of the spring 19 'at this time is equal to the set spring force of the spring 19 of the pressure increasing valve 13 of the front wheel brake system A. After all, the booster valve 13 '
Is the same as the break point b of the front wheel brake system A. Therefore, in the loaded state of the vehicle, the braking force of the vehicle is distributed such that the braking force of the rear wheel is exactly equal to the braking force of the front wheel.

On the other hand, when the vehicle is idle, a predetermined deceleration occurs in the vehicle with a relatively small MCY pressure Pm.
And the break point control piston 41 is fixed. Since the MCY pressure Pm enclosed in the chamber 45 is small, the fixed position of the break point control piston 41 is the leftmost position in FIG.

Therefore, the set length L of the spring 44 when the vehicle is empty is the shortest, so that the spring 44
Since the set spring force when the vehicle is empty is determined to be the maximum, the breaking point of the booster valve 13 'when the vehicle is empty becomes a bending point p at a high position. Thus, in the range of the MCY pressure Pm up to the break point p at which the valve plunger 14 'of the pressure increasing valve 13' starts moving, the W / C pressure Pw increases and decreases along the straight line a, and the MCY pressure exceeding the break point p In the range of Pm, the W / C pressure Pw increases and decreases along the straight line q having the same pressure increasing gradient as the straight line c. At this time, the relationship between the MCY pressure Pm and the W / C pressure Pw is:

[0104]

(Equation 5)

Is given by Therefore, when the vehicle is empty, the braking force of the vehicle is distributed such that the braking force of the rear wheels is smaller than the braking force of the front wheels. Other functions and effects of the negative pressure brake booster system 11 of the fifth example are the same as those of the first example.

In the fifth example, the spring 44 is provided on the small diameter portion 14b 'side of the valve plunger 14'.
The spring force of the spring 44 is applied to the valve plunger 14 '.
The valve portion 14a acts in a direction away from the valve seat 15 '.
4 'on the valve portion 14a side, the spring force of the spring 44 is applied to the valve plunger 14', and the valve portion 14a is
It can be made to act in the direction of sitting. In this case, the spring force of the spring 44 is applied to the break point control piston 41 for controlling the set length L of the spring 44 in a direction in which the break point control piston 41 moves away from the valve plunger 14 ', and the G valve 42 The hydraulic pressure in the chamber 45 controlled by the break point control piston 41
May act in a direction approaching the valve plunger 14 '.

As a means for fixing the break point control piston 41, a G valve 42 composed of a G ball 47 and a valve seat 48 is used. When a predetermined deceleration of the vehicle occurs, the predetermined deceleration is detected. Any means may be used as long as it fixes the break point control piston 41 at the position at that time.

In the above description, one output port of the MCY 8 is connected to the W / C 10 of the front wheel brake, and the other output port is connected to the W / C 10 ′ of the rear wheel brake. Output port is connected to W / C10 of the left front wheel brake and W / C10 'of the right rear wheel brake, and the other output port is connected to the W / C10 of the right front wheel brake and the left rear wheel brake. The present invention can also be applied to a two-system brake system of X piping and a two-system brake system of J piping connected to the W / C 10 '. In this case, the pressure increasing valve 13 and the pressure increasing pump 17 are arranged on the front wheel brake side of the same brake system, and the pressure increasing valve 13 'and the pressure increasing pump 17' are arranged on the rear wheel brake side. do it.

Further, the present invention has been described by applying the present invention to the negative pressure brake booster system 11, but the present invention is not limited to this, and the hydraulic brake booster system and the positive pressure air pressure brake The present invention can be applied to a booster system or a brake booster system having various types of brake boosters even with the same power source, and also to a brake system not having a brake booster.

[0110]

As is apparent from the above description, according to the brake fluid pressure control device of the present invention, the increase of the brake pressure of the rear wheel is controlled to be simply different from the increase of the brake pressure of the front wheel. Thereby, the braking forces of the front and rear wheels can be appropriately distributed.

Further, by controlling the increase in the brake pressure of the rear wheels differently from the increase in the brake pressure of the front wheels in accordance with the load of the vehicle, the braking force of the front and rear wheels is controlled in accordance with the load of the vehicle. Even more appropriate distribution can be achieved.

Further, when the vehicle is idle, the break point at the start of pressure increase of the rear wheel side pressure intensifier valve is set higher than the break point of the front wheel side pressure intensifier valve, so that the braking force of the rear wheel is smaller than the brake force of the front wheel. Thus, the braking force of the vehicle can be distributed. Therefore, by controlling the break point of the rear wheel pressure intensifier valve when the vehicle is idle, it is possible to prevent early locking of the rear wheel, and to more effectively apply the brake of the vehicle according to the load of the vehicle. Become.

Further, when the vehicle is loaded, the breaking point of the rear wheel pressure intensifying valve is set near the breaking point of the front wheel pressure intensifying valve so that the braking force of the rear wheel approaches the braking force of the front wheel. , The braking force of the vehicle can be distributed. Therefore, the vehicle can be more effectively braked during loading.

[Brief description of the drawings]

FIG. 1 is a diagram showing a negative pressure brake boosting system using a first example of an embodiment of a brake fluid pressure control device according to the present invention.

FIG. 2 is a diagram showing input / output characteristics of the brake fluid pressure control device of the example shown in FIG.

FIG. 3 is a diagram showing a negative pressure brake boosting system using a second example of the embodiment of the present invention.

FIG. 4 is a diagram showing input / output characteristics of the brake fluid pressure control device of the example shown in FIGS. 3 and 5;

FIG. 5 is a diagram partially showing a negative pressure brake booster system using a third example of the embodiment of the present invention.

FIG. 6 is a diagram partially showing a negative pressure brake boosting system using a fourth example of an embodiment of the present invention.

7 is a diagram showing input / output characteristics of the brake fluid pressure control device of the example shown in FIG.

FIG. 8 is a diagram partially showing a negative pressure brake booster system using a fifth example of an embodiment of the present invention.

9 is a diagram showing input / output characteristics of the brake fluid pressure control device of the example shown in FIG.

FIG. 10 is a diagram showing a conventional general hydraulic brake booster system.

FIG. 11 is a diagram showing a conventional general negative pressure brake booster system.

FIG. 12 is a diagram showing an example of a conceivable brake system for increasing the brake fluid pressure without using a booster.

[Explanation of symbols]

2… Brake pedal, 8… Master cylinder (MCY),
10, 10 ': wheel cylinder (W / C), 12: negative pressure booster, 13, 13': booster valve, 13a, 13
a ', 32a, 36a ... input ports, 13b, 13b', 32
b, 36b: output port, 14, 14 ', 33, 37: valve plunger, 14a, 14a', 33a, 37a: valve section, 1
4b, 14b ', 33b, 37b ... small diameter portion, 15, 15',
34, 38, 48 ... valve seats, 17, 17 '... pressure boosting pumps,
19,19 ', 35,39,43,44 ... spring, 20,
20 ': hydraulic pressure sensor, 21: electronic control unit (ECU),
22: load response break point control mechanism, 23: load detection lever, 24: axle, 25: tension spring, 26: pressing member,
28: bypass passage, 30: first electromagnetic on / off valve, 31: second electromagnetic on / off valve, 32: proportioning valve (P valve), 36: second pressure increasing valve, 40: deceleration response break point control mechanism, 41: break point control piston, 42: deceleration detection valve, 45: chamber, 46: passage, 47: inertia ball (G ball), A: front wheel brake system, B: rear wheel brake system, L: spring 44 setting length

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hidefumi Inoue 2-11-6 Shinmeicho, Higashimatsuyama-shi, Saitama Automobile Equipment Co., Ltd. Matsuyama Plant (72) Inventor Mamoru Sawada 1-1-1 Showacho, Kariya-shi, Aichi Prefecture Address: Inside Denso Corporation (72) Inventor Shuichi Yonemura 1-1-1, Showa-cho, Kariya City, Aichi Prefecture Inside Denso Corporation (72) Inventor Takahiro Goshima 1-1-1, Showa-cho, Kariya City, Aichi Prefecture Inside Denso Corporation

Claims (11)

[Claims] 1. A brake fluid pressure control device used in a two-system brake system, comprising a front wheel brake pressure increase control device, a rear wheel brake pressure increase control device, and a rear wheel brake pressure increase device. By appropriately setting the pressure increasing characteristic of the pressure increasing control device such that at least a part of the pressure increasing characteristic is different from the pressure increasing characteristic of the front wheel brake pressure increasing pressure controlling device, the braking force of the front and rear wheels is appropriately distributed. A braking fluid pressure control device characterized by the above. 2. A pressure increasing characteristic of the rear wheel brake pressure increasing control device, wherein at least a part of the pressure increasing characteristic is based on a pressure increasing characteristic of the front wheel brake pressure increasing control device according to the load of the vehicle. 2. The brake fluid pressure control device according to claim 1, wherein the braking force of the front and rear wheels is appropriately distributed by setting differently. 3. A front wheel brake system for applying a brake to a front wheel by introducing a hydraulic pressure of a master cylinder to a front wheel side brake cylinder and a brake for a rear wheel by introducing a hydraulic pressure of the master cylinder to a rear wheel side brake cylinder. A front-wheel-side pressure-intensifying valve for increasing the hydraulic pressure of the master cylinder and outputting the same to the front-wheel-side brake cylinder in a front-wheel brake system. The front-wheel-side pressure-intensifying valve has an input port through which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a pressure-increasing hydraulic pressure from the front-wheel-side hydraulic pressure source. When the output port and the hydraulic pressure of the master cylinder are smaller than a first predetermined pressure, the output port communicates with the input port and the output port to communicate with the master cylinder. From the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, shuts off the connection between the input port and the output port, and increases the pressure to the output port. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure by introducing a hydraulic pressure for the master cylinder; A rear-wheel-side pressure-intensifying valve for increasing pressure and outputting the pressure to the rear-wheel-side brake cylinder, and a break point, which is a second predetermined pressure at which the rear wheel-side pressure-increasing valve starts increasing pressure, is changed in accordance with the load. And a load-response break point control means for controlling the rear-wheel-side pressure-increasing valve. From hydraulic pressure source When the output pressure at which the pressure-increasing hydraulic pressure is introduced and the hydraulic pressure of the master cylinder are smaller than a second predetermined pressure, the output port communicates with the input port to output the hydraulic pressure of the master cylinder. The hydraulic pressure is derived from the output port, and when the hydraulic pressure of the master cylinder is equal to or higher than the second predetermined pressure, the pressure between the input port and the output port is shut off. And a valve plunger that derives a hydraulic pressure increased from the master cylinder as the output hydraulic pressure from the output port by introducing a hydraulic pressure of the master cylinder. A brake fluid pressure control device characterized in that it is set so as to apply a pressing force according to the load of the vehicle so as to oppose the fluid pressure at the mouth. 4. A front wheel brake system for applying a brake to a front wheel by introducing a hydraulic pressure of a master cylinder to a front wheel side brake cylinder and a brake for a rear wheel by introducing a hydraulic pressure of the master cylinder to a rear wheel side brake cylinder. A front-wheel-side pressure-intensifying valve for increasing the hydraulic pressure of the master cylinder and outputting the same to the front-wheel-side brake cylinder in a front-wheel brake system. The front-wheel-side pressure-intensifying valve has an input port through which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a pressure-increasing hydraulic pressure from the front-wheel-side hydraulic pressure source. When the output port and the hydraulic pressure of the master cylinder are smaller than a first predetermined pressure, the output port communicates with the input port and the output port to communicate with the master cylinder. From the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, shuts off the connection between the input port and the output port, and increases the pressure to the output port. A valve plunger that derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure by introducing a hydraulic pressure for the master cylinder; A rear-wheel-side pressure-intensifying valve that increases pressure and outputs the pressure to the rear-wheel-side brake cylinder; and a pressure-intensifying valve that connects the master cylinder and the rear wheel-side brake cylinder through the rear-wheel-side pressure-increasing valve. A bypass passage for connecting the master cylinder and the rear wheel side brake cylinder by bypassing the rear wheel side pressure increasing valve; and a bypass passage for connecting the master cylinder and the rear wheel side brake cylinder. A passage switching means for selectively connecting to the rear wheel through the pressure increasing valve side passage when the vehicle is loaded, and via the bypass passage when the vehicle is empty. The pressure valve has an input port through which the hydraulic pressure from the master cylinder is introduced, an output port through which an output hydraulic pressure is derived and a pressure-increasing hydraulic pressure from a rear-wheel-side pressure-increasing hydraulic pressure source, and the master port. When the hydraulic pressure of the cylinder is smaller than the second predetermined pressure, the hydraulic pressure of the master cylinder is derived from the output port as the output hydraulic pressure by communicating between the input port and the output port, and the When the hydraulic pressure is equal to or higher than the second predetermined pressure, the pressure between the input port and the output port is shut off, and the hydraulic pressure of the master cylinder is increased by introducing the hydraulic pressure for pressure increase into the output port. The output hydraulic pressure as the output hydraulic pressure A brake fluid pressure control device comprising a valve plunger derived from an output port. 5. A proportioning valve for reducing the hydraulic pressure of the master cylinder and outputting the reduced hydraulic pressure to the rear wheel side brake cylinder when the hydraulic pressure of the master cylinder reaches a third predetermined pressure is provided in the bypass passage. The brake fluid pressure control device according to claim 4, wherein the brake fluid pressure control device is provided. 6. The hydraulic pressure of the master cylinder at the break point of the rear wheel-side pressure-intensifying valve, wherein the hydraulic pressure of the master cylinder at the break point at which the pressure increase starts in the bypass passage is the same as that of the rear wheel-side pressure-intensifying valve. 5. The brake fluid pressure control device according to claim 4, further comprising a second rear wheel pressure increasing valve set higher. 7. The brake fluid according to claim 6, wherein the pressure increasing gradient of the second rear wheel pressure increasing valve is set smaller than the pressure increasing gradient of the rear wheel pressure increasing valve. Pressure control device. 8. The brake fluid pressure control device according to claim 4, wherein said passage switching means includes an electromagnetic switching valve. 9. A front wheel brake system for applying a brake to a front wheel by introducing a hydraulic pressure of a master cylinder to a front wheel side brake cylinder and a brake for a rear wheel by introducing a hydraulic pressure of the master cylinder to a rear wheel side brake cylinder. A front-wheel-side pressure-intensifying valve for increasing the hydraulic pressure of the master cylinder and outputting the same to the front-wheel-side brake cylinder in a front-wheel brake system. The front-wheel-side pressure-intensifying valve has an input port through which the hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a pressure-increasing hydraulic pressure from the front-wheel-side hydraulic pressure source. When the output port and the hydraulic pressure of the master cylinder are smaller than a first predetermined pressure, the output port communicates with the input port and the output port to communicate with the master cylinder. From the output port as the output hydraulic pressure, and when the hydraulic pressure of the master cylinder is equal to or higher than the first predetermined pressure, shuts off the connection between the input port and the output port, and increases the pressure to the output port. And a valve plunger that derives the output pressure from the output port as a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder by introducing a hydraulic pressure for the master cylinder. A rear wheel-side pressure increasing valve for increasing pressure and outputting the pressure to the rear wheel-side brake cylinder; and a turning point which is a second predetermined pressure at which the rear wheel side pressure increasing valve starts increasing pressure, according to the vehicle deceleration. A deceleration response break point control means for performing change control is provided, and the rear wheel side pressure increasing valve is configured to derive an input port through which hydraulic pressure from the master cylinder is introduced, an output hydraulic pressure, and a rear wheel pressure. From hydraulic pressure source for side pressure increase When the hydraulic pressure of the master cylinder is lower than a second predetermined pressure, the output port through which the pressure-increasing hydraulic pressure is introduced is communicated with the input port and the output port to output the hydraulic pressure of the master cylinder to the output port. The hydraulic pressure is derived from the output port, and when the hydraulic pressure of the master cylinder is equal to or higher than the second predetermined pressure, the pressure between the input port and the output port is shut off, and the pressure increasing hydraulic pressure is applied to the output port. And a valve plunger which derives from the output port a hydraulic pressure obtained by increasing the hydraulic pressure of the master cylinder as the output hydraulic pressure, and the deceleration response break point control means increases the hydraulic pressure of the valve plunger. A brake fluid pressure control device characterized in that the start is changed and controlled according to the deceleration of the vehicle. 10. The deceleration response break point control means operates by detecting a break point control piston for changing a break point at which the pressure increase of the valve plunger is started, and a predetermined deceleration of the vehicle. 10. The brake fluid pressure control device according to claim 9, further comprising deceleration detection means for controlling a breaking point changing operation of the control piston. 11. A break point which is the first predetermined pressure of the pressure increasing valve of the front wheel brake system and the second predetermined pressure of the pressure increasing valve of the rear wheel brake system when the vehicle is loaded are set to be equal. The brake fluid pressure control device according to any one of claims 3 to 10, wherein