JP3133173B2 - Brake fluid pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device capable of controlling output fluid pressure relative to supply fluid pressure.

[0002]

2. Description of the Related Art Conventionally, as a brake fluid pressure control device,
For example, the one described in JP-A-4-88767 is known.

This conventional brake fluid pressure control device comprises a master cylinder for generating a master cylinder pressure based on a brake operation, an external fluid pressure supply source for supplying a fluid pressure higher than the master cylinder pressure, and an external fluid pressure supply source. And a second plunger as a pressure-intensifying actuator for actuating the spool in the output hydraulic pressure increasing direction by receiving the master cylinder pressure by receiving the master cylinder pressure and a spool that adjusts the output hydraulic pressure by sliding the supply hydraulic pressure from the hydraulic pressure source as a hydraulic pressure source A hydraulic pressure control valve having a large-diameter first plunger for reducing the rigidity of the brake, and an output hydraulic pressure from the hydraulic pressure control valve and a master cylinder pressure connected to each other so that when no output hydraulic pressure is generated, the master cylinder The pressure is supplied directly to the wheel cylinder, and when the output hydraulic pressure is generated, the output hydraulic pressure increased based on the pressure receiving area difference of the step plunger is used as the master cylinder. It was equipped with a brake pressure combiner having a supply failsafe function.

[0004]

However, in such a conventional brake fluid pressure control device, as described above, the output fluid pressure from the fluid pressure control valve due to the occurrence of an abnormality in the external fluid pressure supply source or the like, as described above. When the occurrence of the brake is eliminated, the master cylinder pressure is directly supplied to the wheel cylinders by the fail-safe operation of the brake pressure synthesizer, so that during the fail-safe operation, the rigidity of the wheel system is added to the rigidity of the brake system. In such a case, there is a problem that the brake response becomes poor and the driver feels uneasy.

The present invention has been made in view of the above-mentioned conventional problems, and is intended to prevent a decrease in the rigidity of a brake system during a fail-safe operation, thereby improving brake responsiveness. It is intended to provide a device.

[0006]

In order to achieve the above-mentioned object, a brake hydraulic pressure control device according to the present invention comprises a master cylinder for generating a master cylinder pressure based on a brake operation, and a hydraulic pressure higher than the master cylinder pressure. The output hydraulic pressure is increased by receiving the master cylinder pressure and the spool that regulates the output hydraulic pressure by sliding using the external hydraulic pressure supply source, the supply hydraulic pressure from the external hydraulic pressure supply as the hydraulic pressure source A hydraulic control valve having a pressure increasing actuator for operating a spool in the direction, a wheel cylinder for generating a braking force for each wheel by receiving an output hydraulic pressure from the hydraulic control valve, and an output of the hydraulic control valve When the hydraulic pressure drops, a fail-safe valve that supplies hydraulic pressure based on the master cylinder pressure to the wheel cylinders instead of the output hydraulic pressure, and a A stroke accumulator for securing the stroke amount of the cylinder, a cut valve for stopping the operation of the stroke accumulator by receiving the supply hydraulic pressure from the external hydraulic pressure supply source, and also for ensuring the operation of the stroke accumulator by reducing the supply hydraulic pressure. The fail-safe valve has a large-diameter piston portion at both ends.
And a stepped piston formed with a small-diameter piston section and
The large-diameter piston portion is slidably housed and
Master cylinder pressure is introduced to the outer end face side of the piston part.
The large-diameter cylinder chamber and the small-diameter piston
And the outer end face side of the small-diameter piston portion is
The small-diameter cylinder chamber communicated with the
Formed between the large diameter piston and the small diameter piston.
An intermediate chamber connected to the output side of the hydraulic pressure control valve.
A valve body and a front side provided in the valve body.
A pusher for urging the stepped piston toward the large-diameter cylinder chamber
And the stepped piston is formed on the stepped piston.
A communication hole communicating between the intermediate chamber and the small-diameter cylinder chamber;
Sliding of the stepped piston toward the small-diameter piston part
A check valve that acts in the direction to close the communication hole.
It has a configuration that.

[0007]

In the brake fluid pressure control device of the present invention, since it is configured as described above, when the output fluid pressure from the fluid pressure control valve is normal, the supply fluid from the external fluid pressure supply source is provided. Since the pressure is also acting on the cut valve, the cut operation of the cut valve is stopped, and the stroke accumulator is operable.

When the supply of hydraulic pressure from the external hydraulic pressure supply source stops, the operation of the stroke accumulator is stopped by the cut action of the cut valve, thereby reducing the rigidity of the brake system during the fail-safe operation. As a result, the responsiveness of the brake can be increased.
In addition, the occurrence of an abnormality in the external hydraulic pressure supply
When the output hydraulic pressure becomes zero, the fail-safe valve
Because the supply fluid pressure to
Pressing force to the left due to pressure receiving area difference from small diameter piston
Is in the state of 0. So, in this state brake
When the operation is performed, the master cylinder pressure of the master cylinder
Increases according to the operation, and the master cylinder pressure becomes
It is supplied to the large-diameter cylinder chamber of the fail-safe valve,
The master cylinder pressure must be received by the large-diameter piston.
The stepped piston resists the biasing force of the spring
Press and slide in the direction of the small diameter cylinder chamber.
The communication hole is closed from the small-diameter cylinder chamber side by the check valve.
And the communication between the intermediate chamber and the small-diameter cylinder chamber is released.
The stepped piston slides, and the small-diameter piston
To compress the fluid in the small-diameter cylinder chamber,
Increase the hydraulic pressure of the wheel cylinder to
Power can be secured. And this wheel
Master cylinder pressure is larger than that of small diameter cylinder
With the pressure increased by the pressure receiving area ratio with the diameter cylinder.
Which is used during fail-safe operation.
Function to boost the brake operation force (hydraulic brake)
And a strong braking force can be obtained.
Become so.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. (First Embodiment) First, the configuration of the first embodiment will be described. In this embodiment, a drive wheel side brake fluid pressure control device will be described.

FIG. 1 is an overall configuration diagram showing a brake fluid pressure control device according to an embodiment of the present invention. As shown in FIG. 1, the brake fluid pressure control device according to this embodiment includes a brake pedal 2a.
Master cylinder 2 for generating a master cylinder pressure corresponding to the operation amount of the vehicle, a wheel cylinder 3 provided in a wheel brake device, an external hydraulic pressure supply source 6, a drive wheel hydraulic pressure control valve 7, and a cut valve 8 And the fail-safe valve 10
, A brake controller 13, a stroke accumulator 20, and a solenoid valve 21.

The external hydraulic pressure source 6 includes a hydraulic pump 6a
And a check valve 6b for preventing backflow, an accumulator 6c for storing high-pressure liquid, and a relief valve 6e provided in the middle of the hydraulic pressure supply liquid passage 14 of the hydraulic pump 6a.

FIG. 2 is a sectional view showing the drive wheel hydraulic pressure control valve 7. In the figure, reference numeral 1 denotes a valve body, in which a valve hole 11 is formed. ing. A hydraulic pressure supply port 11a and a drain port 11b are formed in the valve hole 11, and an output port 11 is located between the ports 11a and 11b.
c is formed.

As shown in the system diagram of FIG. 1, the hydraulic pressure supply port 11a is connected to an external hydraulic pressure source 6 through a hydraulic pressure
1b is connected to the drain tank T via the drain-side connection port 1b and is at atmospheric pressure, and the output port 11c is connected to the wheel cylinder 3 via the fail-safe valve 10.

The valve spool 4 is slidably housed in the valve hole 11. The valve spool 4 has an annular communication groove 4a for communicating between the hydraulic pressure supply port 11a and the output port 11c, and the output port 1
An annular communication groove 4b is formed to allow communication between the drain communication port 1c and the drain port 11b, and the two annular communication grooves 4a, 4b are formed.
A throttle land 4c is formed between the output ports 11c so as to overlap with the output port 11c.
The variable apertures s and t are formed between the variable apertures 1 and 2.

That is, when the valve spool 4 slides to the left in the drawing, the variable throttle s is shut off and the variable throttle t is opened, so that the hydraulic pressure at the output port 11c changes in a direction to increase. When the valve spool 4 slides rightward in the drawing, contrary to the above, the variable throttle s opens and the variable throttle t
Shuts off. As a result, the output hydraulic pressure of the output port 11c changes in a decreasing direction.

A solenoid 5a for a traction control system (hereinafter abbreviated as TCS), which slides the valve spool 4 by a suction force generated by energization, is provided at an outer peripheral position of both right and left ends of the valve spool 4; A solenoid 5b for a brake system (hereinafter abbreviated as ABS) is provided, and when the solenoid 5a for TCS is energized, the valve spool 4 is slid to the left in the drawing to increase the hydraulic pressure of the output port 11c.
Conversely, when the ABS solenoid 5b is energized, the valve spool 4 is slid rightward in the drawing to decrease the output hydraulic pressure of the output port 11c.

Each of the solenoids 5a and 5b has solenoid body portions B ₁ and B ₂ , coil portions K ₁ and K ₂ , and plunger portions 54a and 54b.

The solenoid body portions B ₁ and B ₂ include bases 51a and 51b fixed to end faces of the valve body 1 by bolts 60a and 60b, and bases 51a and 51b.
The intermediate cylinders 56a and 56b fitted and fixed to the intermediate cylinders 56a and 56b, and the suction members 58 fitted to the intermediate cylinders 56a and 56b
a, 58b.

The coil portions K ₁ and K ₂ include coils 53 a and 53 _b for generating a magnetic field, and coils 53 a and 53 _b.
Hobbins 55a, 55b made of non-magnetic material wound with b
And coil casings 52a and 52b that cover the outer periphery of the hobbins 55a and 55b. The coil portions K ₁ and K ₂ are detachably mounted on the outer circumferences of the solenoid body portions B ₁ and B ₂ , and are screwed around the outer circumferences of respective ends of an adjustment member 9 and the suction member 58 b described later. The lock nut 72 and the fastening nut 59 are exchangeably attached to each other.

At the center of the bases 51a and 51b,
Plunger chambers 62a, 62b larger in diameter than valve hole 11
Are formed, and the plunger portions 54a and 54b are slidably accommodated in the through holes 57a and 57b via bushes 100a and 100b. And both ends of the valve spool 4
The plunger portion 62a extends to the inside of the plunger chamber 62a. The plunger portions 54a and 54b are restricted from moving in the axial direction by two E-shaped rings 41a and 41b, respectively, on the outer periphery of the end portion. Is installed in a state where it is possible.

The suction members 58a and 58b, the coil casings 52a and 52b, and the bases 51a and 51b
, Bushes 100a, 100b, and plunger portion 54
a and 54b are each formed of a magnetic material, and a magnetic loop is formed by these members. Magnetic leakage portions 61a, 61b having a triangular cross section for generating a force for attracting the plunger portions 54a, 54b are formed on the inner end surfaces of the suction members 58a, 58b.

In the through hole 71 of the suction member 58a,
The adjusting member 9 is screwed. And this adjusting member 9
Return spring 4d between the valve spool 4
Are mounted in a compressed state, and the repulsive force presses and biases the valve spool 4 rightward in the drawing. Therefore, in a state where the power is not supplied to both the solenoids 5a and 5b, the valve spool 4 is pressed rightward in the drawing, and the output hydraulic pressure of the output port 11c is in the atmospheric pressure state. The set force of the return spring 4d can be arbitrarily adjusted by changing the screwing amount of the adjusting member 9 into the suction member 58a.

A stopper pin 80 is provided at the axial center of the inner end face of the adjusting member 9 so as to protrude toward the end face of the valve spool 4, while the end face of the valve spool 4 facing the stopper pin 80 is provided. A piston sliding hole 63 communicating with the output port 11c is formed in the shaft center, and a cylindrical reaction force piston 64 is formed in the piston sliding hole 63.
Are slidably provided.

On the other hand, a pilot chamber 66 into which a cylindrical pilot piston 65 is slidably formed is formed at the axial center of the inner end surface of the suction member 58b.
The outer end face of the pilot chamber 8b is provided with an orifice 68 for preventing the pilot piston 65 from damping.
A master cylinder pressure introduction port 67 communicated with 6 is formed. The master cylinder pressure inlet 67 is
As shown in FIG. 1, it is connected to the master cylinder 2 via a master cylinder pressure fluid path 15.

The axial center of the end face of the plunger 62b facing the inner end face of the pilot piston 65 includes:
A stopper pin 42 whose protrusion contacts the pilot piston 65 is press-fitted and fixed.

The plunger chambers 62a and 62b
Is the orifice 1 for preventing damping of the valve spool 4
2 and are connected to the reservoir tank T via the drain side connection port 1b.

Next, as shown in FIG. 3, the cut valve 8 includes a master cylinder pressure introducing chamber 8a for introducing a master cylinder pressure and an external hydraulic pressure introducing chamber 8b for introducing a high external supply pressure. Is defined by a partition wall 8c, and between the two chambers 8a and 8b is communicated with each other by a valve port 8d opened at the center of the partition wall 8c. A ball valve 8f urged in a direction to close the valve port 8d by a spring 8e is accommodated in the master cylinder pressure introducing chamber 8a, and an external supply hydraulic pressure is accommodated in the external hydraulic pressure introducing chamber 8b. And a spring 8h that presses and slides the piston 8g in a direction away from the master cylinder pressure introduction chamber 8a and accommodates the piston 8g. The piston 8g slides in the direction of the master cylinder pressure introducing chamber 8a, so that the valve port 8d
There is provided a pressing pin 8j for pressing the ball valve 8f in a direction to open the ball valve 8f. The stroke accumulator 20 is provided in communication with the external hydraulic pressure introduction chamber 8b near the partition 8c.

As shown in detail in FIG. 4, the fail-safe valve 10 has a stepped piston 10 having a large-diameter piston portion 10a and a small-diameter piston portion 10b formed at both ends.
c, the large-diameter piston portion 10a is slidably housed, and the large-diameter cylinder chamber 10d and the small-diameter piston portion 10b, into which the master cylinder pressure is introduced, are slidably housed on the outer end surface side of the large-diameter piston portion 10a. The hydraulic control valve 7 is formed between the small-diameter cylinder chamber 10e and the large-diameter piston section 10a and the small-diameter piston section 10b, and the outer end face side of the small-diameter piston section 10b communicates with the wheel cylinder 3.
A valve body 10g having an intermediate chamber 10f connected to the output port 11c, a spring 10h provided in the valve body 10g, for urging the piston 10c toward the large-diameter cylinder chamber 10d, and a piston 10c. A communication hole 10j that communicates between the intermediate chamber 10f and the small-diameter cylinder chamber 10e, and a check valve 10k that acts in a direction to close the communication hole 10j by sliding the piston 10c toward the small-diameter piston portion 10b. It has a structure.

As shown in FIG. 1, the solenoid valve 21 has a normal position in which the master cylinder pressure fluid path 15 is simply in a communicating state when the solenoid is not energized, and a master cylinder pressure through a throttle in a state in which the solenoid is energized. Fluid 1
5 and two ABS positions for making the communication state.

Next, the brake controller 13
As shown in FIG. 1, based on input signals from a vehicle speed sensor 18 and a wheel rotation sensor 19, the TCS solenoid 5a
And an ABS control unit for controlling the driving of the ABS solenoid 5b.

Next, the operation of the embodiment will be described.

(A) Non-braking When the brake pedal 2a is not depressed, the master cylinder pressure of the master cylinder 2 at each wheel becomes 0. Therefore, the hydraulic pressure control valve 7 is controlled by the set force of the return spring 4d. The spool 4 is pressed and slid in the right direction in FIG. 2, and the output hydraulic pressure of the output port 11c is O.

Therefore, the hydraulic pressure supplied to each wheel cylinder 3 is also O, and the brake device is inoperative.

(B) Normal braking At this time, the cut valve 20 is in the normal position state after the power supply to the solenoid is released, and the master cylinder pressure is reduced to the master cylinder pressure inlet 67 of the hydraulic pressure control valve 7. It is supplied to both the large-diameter cylinder chamber 10 d of the fail-safe valve 10 and the external hydraulic pressure introduction chamber 8 b of the cut valve 8.
, A high external hydraulic pressure is introduced, and FIG.
As shown in the figure, the piston 8g is pressed and slid in the left direction in the drawing, and the pressing pin 8j is opened in the direction in which the valve port 8d is opened.
f, the stroke accumulator 20 is in communication with the master cylinder pressure liquid passage 15.

Then, when the brake pedal 2a is depressed, the master cylinder pressure of the master cylinder 2 rises in accordance with the depressing force, and the hydraulic pressure is applied to the hydraulic pressure control valve 7 via the master cylinder pressure inlet 67 and the orifice 68. The pilot piston 65 receives pressure and the pilot piston 6
2, the valve spool 4 is pressed and slid leftward in FIG. 2 against the set force of the return spring 4d by this pressing force. By increasing the output hydraulic pressure of the output port 11c, the supply hydraulic pressure to the wheel cylinder 3 increases.

On the other hand, the output hydraulic pressure of the output port 11c is received by the reaction force piston 64,
When the sliding of the reaction force piston 64 is restricted by the stopper pin 80, the pressure receiving reaction force of the reaction force piston 64 acts on the valve spool 4 as a feedback force. Thereby, the valve spool 4 is pushed back to the right in FIG.

That is, the valve spool 4 applies the pressing force of the pilot piston 65 and the pressure receiving reaction force of the reaction force piston 64 +
It is arranged at a position where the set force of the return spring 4d is balanced. In this case, since the pressure receiving cross-sectional area of the pilot piston 65 is larger than that of the reaction force piston 64, the output hydraulic pressure (W / W) with respect to the master cylinder pressure (M / CYL pressure) as shown in the boosting function characteristic of FIG. / CYL pressure) is increased by the pressure receiving cross-sectional area ratio of the pistons 65 and 64, whereby the master cylinder pressure for the wheel cylinder 3 is increased to a predetermined magnification (about 9 times in the embodiment).
Is supplied in a state where the pressure is increased, that is, the brake pedal 2
The boosting function (hydraulic pressure booster function) for boosting the pedaling force a is exhibited, and a strong braking force can be obtained.

As shown in FIG. 4, the output hydraulic pressure of the hydraulic pressure control valve 7 is introduced into the intermediate chamber 10f of the fail-safe valve 10 and then passed through the communication hole 10j and the small-diameter cylinder chamber 10e. It is in a state of being supplied to the cylinder 3.

At this time, the master cylinder pressure is supplied to the large-diameter cylinder chamber 10d of the fail-safe valve 10, and the pressing force F for pressing the piston 10c rightward in FIG.
₁ is acting, but the urging force of the spring 10h acts in the direction of pressing the piston 10c leftward in FIG. 4, and the increased output hydraulic pressure is supplied to the intermediate chamber 10f. , A pressing force F ₂ having the pressure receiving area difference between the large-diameter piston portion 10a and the small-diameter piston portion 10b.
There have been acting in the direction of pressing in the left direction of the piston 10c in FIG. 4, in particular, the pressing force F ₂ is the master cylinder pressure as described above is boosted at a predetermined magnification (about 9 times in the embodiment) Pressure F
₂ + biasing force> pressing force F ₁
Accordingly, the piston 10a is pressed to the left in FIG. 4, and the communication hole 10j is kept open.

Accordingly, the stiffness of the brake system at this time is such that the stiffness of the stroke of the stroke accumulator 20 is added to the stiffness of the stroke of the master cylinder 2, thereby eliminating the feeling of stepping on the stone when the brake pedal 2a is operated. can do.

(C) At the time of ABS operation At the time of sudden braking or at the time of braking on a low μ road such as a snowy road, the frictional resistance of the tire to the road surface becomes smaller than the braking frictional resistance of the wheel by the braking device, and the tire slips. Then, the wheels are locked.

Therefore, AB of the brake controller 13
In the S control unit, when the slip state of the tire is detected from the vehicle speed detected by the vehicle speed sensor 18 and the wheel rotation speed detected by the wheel rotation sensor 19, the hydraulic pressure for the driving wheel is determined according to the slip amount. The drive current is applied to the control valve 7 and the ABS solenoid 5b of the driven wheel brake fluid pressure control device 8, and the drive current is also applied to the solenoid of the solenoid valve 21 to be in the ABS position state. Therefore, the master cylinder pressure is supplied to the master cylinder pressure inlet 67 of the hydraulic pressure control valve 7 and the large-diameter cylinder chamber 10d of the fail-safe valve 10 via the throttle.

As described above, A of the hydraulic pressure control valve 7
When a current is applied to the BS solenoid 5b, the suction member 58b, the coil casing 52b, and the base 51b
The bush 100b and the plunger portion 54b form a magnetic loop, and the plunger portion 54b is slid rightward in FIG. 2 to a magnetic leakage portion 61b having a triangular cross section formed on the inner end surface of the attraction member 58b. A suction force is generated, which causes the valve spool 4 to return the return spring 4
It is pushed back to the right in FIG. 2 by the set force of d.

That is, the pressing force of the pilot piston 65 generated by the brake operation, the pressure receiving reaction force of the reaction force piston 64 + the set force of the return spring 4d + the suction force,
The valve spool 4 is arranged at a position where the pressure is balanced, that is, the valve spool 4 is pushed back to the right in FIG. 2 by an amount corresponding to the suction force, whereby the output hydraulic pressure (the hydraulic pressure supplied to the wheel cylinder 3) decreases. Then, as the braking force of the wheels decreases, the slip amount of the wheels decreases.

Then, AB of the brake controller 13
In the S control unit, the detected slip amount is constantly compared with a preset appropriate slip amount (braking force), and the current applied to the ABS solenoid 5b is adjusted so that the detected slip amount becomes an appropriate slip amount. Is controlled. That is, the output hydraulic pressure (W / CY) with respect to the master cylinder pressure (M / CYL pressure) is within the range of the ABS function shown in FIG.
L pressure) characteristics can be changed.

During the ABS control, as described above, since the solenoid valve 21 is in the ABS position, the master cylinder pressure is supplied to the master cylinder pressure inlet 67 of the hydraulic pressure control valve 7 via the throttle. Thus, the fluctuation of the hydraulic pressure of the wheel cylinder 3 due to the change in the depression force of the brake pedal 2a is suppressed.

(D) At the time of TCS operation When the vehicle suddenly starts or accelerates, the accelerator torque depresses and the engine torque sharply increases. This engine torque overcomes the frictional force of the driving wheel tire on the road surface. A tire slip phenomenon occurs. That is, the rotation speed of the wheels becomes higher than the vehicle speed, and if left unattended, the steering becomes unstable.

Therefore, the TC of the brake controller 13
In the S control unit, when the slip state of the tire is detected from the vehicle speed detected by the vehicle speed sensor 18 and the wheel rotation speed detected by the wheel rotation sensor 19, the hydraulic pressure for the driving wheel is determined according to the slip amount. A drive current is applied to the TCS solenoid 5a of the control valve 7.

As described above, when a current is applied to the TCS solenoid 5a, a magnetic loop is formed by the suction member 58, the coil casing 52a, the base 51a, the bush 100a, and the plunger portion 54a, and the suction is performed. Attraction force to slide the plunger portion 54a leftward in FIG. 2 is generated in the magnetic leakage portion 61a having a triangular cross section formed on the inner end surface of the member 58, and the suction force is transmitted through the E-ring 41 to the valve spool. 4, the valve spool 4 is pressed and slid in the leftward direction in FIG. 2, thereby increasing the output hydraulic pressure of the output port 11c and increasing the supply hydraulic pressure to the wheel cylinder 3.

On the other hand, the output hydraulic pressure of the output port 11c is received by the reaction force piston 64,
When the sliding of the reaction force piston 64 is restricted by the stopper pin 80, the pressure receiving reaction force of the reaction force piston 64 acts on the valve spool 4 as a feedback force. Thereby, the valve spool 4 is pushed back rightward in FIG. That is, the valve spool 4 is disposed at a position where the suction force by the TCS solenoid 5a and the pressure receiving reaction force of the reaction force piston 64 + the set force of the return spring 4d are balanced.
The valve spool 4 is pressed and slid in the leftward direction in FIG. 2 by the suction force. As a result, the output hydraulic pressure (the supply hydraulic pressure to the wheel cylinder 3) increases despite no brake operation. As a result, a wheel braking force is generated, thereby reducing the wheel slip amount.

The TC of the brake controller 13
In the S control unit, the detected slip amount is constantly compared with a preset appropriate slip amount (driving force), and the applied current value to the TCS solenoid 5a is adjusted so that the detected slip amount becomes an appropriate slip amount. Is controlled. That is, the output hydraulic pressure (W / CYL pressure) can be generated within the range of the TCS function shown in FIG.

(E) Fail safe operation When the output hydraulic pressure of the hydraulic pressure control valve 7 becomes 0 due to the occurrence of an abnormality in the external hydraulic pressure supply source 6, the fail safe valve 10 shown in FIG.
In this case, since the supply pressure to the intermediate chamber 10f becomes zero, the leftward pressing force due to the pressure receiving area difference between the large-diameter piston portion 10a and the small-diameter piston portion 10b is zero.

When the brake pedal 2a is depressed in this state, the master cylinder pressure of the master cylinder 2 increases in accordance with the depression force, and this master cylinder pressure is supplied to the large-diameter cylinder chamber 10d of the fail-safe valve 10. By receiving the master cylinder pressure at the large-diameter piston portion 10a, the piston 10c
4 is pressed and slid rightward in FIG. 4 against the urging force of h.

When the piston 10c slides rightward in FIG. 4, the communication hole 10j is first closed from the small-diameter cylinder chamber 10e side by the check valve 10k, and the communication between the intermediate chamber 10f and the small-diameter cylinder chamber 10e is established. When the piston 10c is further slid to the right in FIG. 4, the fluid in the small-diameter cylinder chamber 10e is compressed by the small-diameter piston 10b, whereby the hydraulic pressure of the wheel cylinder 3 is increased, and A braking force can be secured.

The master cylinder pressure is supplied to the wheel cylinder 3 in a state where the master cylinder pressure is increased according to the pressure receiving area ratio between the small-diameter cylinder 10b and the large-diameter cylinder 10a. In this case, the boosting function (hydraulic pressure booster function) for boosting the depression force of the brake pedal 2a is exhibited, and a strong braking force can be obtained.

At this time, the cut valve 8
As shown in (b), since the hydraulic pressure in the external hydraulic pressure introduction chamber 8b is lost, the piston 8g is pressed and slid in the direction away from the master cylinder pressure introduction chamber 8a by the urging force of the spring 8h. Accordingly, the ball valve 8f is pressed in a direction to close the valve port 8d by the urging force of the spring 8e.

Accordingly, since the communication between the stroke accumulator 20 and the master cylinder pressure fluid path 15 is stopped, the rigidity of the brake system at this time is determined by the rigidity of the master cylinder 2 due to the stroke. The rigidity of the safe valve 10 due to the stroke of the piston 10k is increased, but the rigidity of the stroke accumulator 20 due to the stroke is lost, so that the rigidity of the entire brake system does not decrease.

As described above, this embodiment has the following advantages.

It is possible to prevent a decrease in the rigidity of the brake system during the fail-safe operation, thereby improving the responsiveness of the brake. Further, when the external hydraulic pressure source 6 is lowered,
At the time of fail-safe operation, the wheel cylinder 3
The master cylinder pressure is smaller than that of the small-diameter cylinder chamber 10e.
Pressure increased by the pressure receiving area ratio with the cylinder chamber 10d
By providing the fail-safe valve 10 supplied in a state,
Even during the fail-safe operation, the brake pedal 2a
Boost function (hydraulic pressure booster function) that boosts the pedal effort
As a result, a strong braking force can be obtained.

The hydraulic pressure control valve 7 has a structure in which a hydraulic booster mechanism that exhibits a boosting function is compactly incorporated, so that the brake hydraulic pressure control system as a whole can be reduced in weight and size, and can be mounted on a vehicle. Get higher.

(Second Embodiment) Next, a brake fluid pressure control device according to a second embodiment will be described. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only the differences from the first embodiment will be described.

That is, this embodiment is different from the first embodiment in that a stroke accumulator 22 having a built-in cut valve function is used as shown in the system diagram of FIG.

That is, the stroke accumulator 22
As shown in FIG. 7, an annular stopper member 2 is provided between a master cylinder pressure introducing chamber 22a communicating with each other and an external hydraulic pressure introducing chamber 22b into which a high external supply hydraulic pressure is introduced.
2c is provided, and the master cylinder pressure introduction chamber 22a is provided.
A first piston 22d is slidably housed therein, and a second piston 22e is slidably housed in the external hydraulic pressure introduction chamber 22b. A second spring 22f is interposed between the pistons 22d and 22e, and the piston 2d is provided on the master cylinder pressure receiving side of the first piston 22d.
A first spring 22g that presses and biases 2d toward the external hydraulic pressure introduction chamber 22b is provided. The first spring 22g has a smaller urging force than the second spring 22f. The inner peripheral surface of the stopper member 22c has an air communication hole 22h communicating the inside and the outside.
Are formed.

The stroke accumulator 2 of this embodiment
2 is configured as described above, and when the supply hydraulic pressure from the external hydraulic pressure supply source 6 is supplied to the external hydraulic pressure introduction chamber 22b in a normal state, as shown in FIG. Since the second piston 22e is pressed leftward in the drawing by receiving the high supply liquid pressure, the first piston 22d is pressed and slid leftward in the drawing by the urging force of the second spring 22g. ing. Accordingly, in this state, when the master cylinder pressure is supplied into the master cylinder pressure introduction chamber 22a, the first piston 22d is pressed and slid rightward in the drawing, that is, the first piston 22d and the second piston The stroke accumulator function can be exhibited with the spring 22f.

Next, when the supply of hydraulic pressure to the external hydraulic pressure introduction chamber 22b stops due to the occurrence of an abnormality in the external hydraulic pressure supply source 6, the first piston 2g is biased by the first spring 22g.
Since the 2d and the second piston 22e are pressed and slid in the right direction in the drawing, and the first piston 22d comes into contact with the stopper member 22h, the stroke accumulator function is stopped. That is, in this embodiment, the cut valve function can be exhibited by the external hydraulic pressure introduction chamber 22b into which the supply hydraulic pressure from the external hydraulic pressure supply source 6 is introduced, the second piston 22e, and the second spring 22f. .

Therefore, also in the second embodiment, the same effects as in the first embodiment can be exhibited.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. Included in the invention.

[0068]

As described above, in the brake fluid pressure control device of the present invention, a stroke accumulator interposed in the middle of the master cylinder pressure fluid passage to secure the stroke amount of the master cylinder, A cut valve that stops the operation of the stroke accumulator by ensuring the operation of the stroke accumulator by receiving the supply hydraulic pressure from the external hydraulic pressure supply source and lowering the supply hydraulic pressure provides The effect is obtained that the responsiveness of the brake can be improved by preventing the reduction in the rigidity of the brake system. Also outside
When failsafe operation is performed when the hydraulic pressure supply source drops
The master cylinder pressure against the wheel cylinder
Depending on the pressure receiving area ratio between the small-diameter cylinder chamber and the large-diameter cylinder chamber,
Equipped with a fail-safe valve that is supplied under pressure
As a result, even during fail-safe operation, the brake
Demonstrate the boost function (hydraulic pressure booster function) to boost the operating force
It is said that it will be possible to obtain a strong braking force
The effect is obtained.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing a hydraulic pressure control valve in the brake hydraulic pressure control device of the first embodiment.

FIG. 3 is a cross-sectional view illustrating details of a cut valve and its operation in the brake fluid pressure control device according to the first embodiment.

FIG. 4 is a sectional view showing details of a fail-safe valve.

FIG. 5 is a hydraulic pressure characteristic diagram of the brake hydraulic pressure control device of the first embodiment.

FIG. 6 is an overall system diagram showing a brake fluid pressure control device according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating details of a cut valve and its operation in a brake fluid pressure control device according to a second embodiment.

[Explanation of symbols]

 2 Master cylinder 3 Wheel cylinder 4 Valve spool 6 External hydraulic pressure supply source 7 Hydraulic pressure control valve 8 Cut valve 10 Fail safe valve 15 Master cylinder pressure hydraulic fluid path 20 Stroke accumulator 22 Stroke accumulator 22b External hydraulic pressure introduction chamber (cut valve) 22e 2nd piston (cut valve) 22f 2nd spring (cut valve) 65 Pilot piston (actuator for pressure increase)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T 8/00-8/96 B60T 15/36

Claims (1)

(57) [Claims] 1. A master cylinder for generating a master cylinder pressure based on a brake operation, an external hydraulic pressure supply source for supplying a hydraulic pressure higher than the master cylinder pressure, and a hydraulic pressure supply from the external hydraulic pressure source A hydraulic pressure control valve having a spool that regulates the output hydraulic pressure by sliding as a source and a pressure increasing actuator that operates the spool in the output hydraulic pressure increasing direction by receiving the master cylinder pressure; and The wheel cylinder that generates braking force for each wheel by receiving the output hydraulic pressure of the wheel, and supplies the wheel cylinder with hydraulic pressure based on the master cylinder pressure instead of the output hydraulic pressure when the output hydraulic pressure of the hydraulic pressure control valve decreases A fail-safe valve, a stroke accumulator interposed in the master cylinder pressure fluid path to secure the stroke of the master cylinder, and an external hydraulic pressure supply. And a cut valve for stopping the operation of the stroke accumulator due to a decrease in supply pressure while ensuring the operation stroke accumulator by pressure supply fluid pressure from sources, the fail-safe valve, large diameter at both ends Piston and small
A stepped piston formed with a diameter piston portion;
The large diameter piston is accommodated slidably in the large diameter piston.
The master cylinder pressure is introduced to the outer end face side of the ton section.
Diameter cylinder chamber and the small diameter piston section are slidably housed.
And the outer end face side of the small-diameter piston portion is
Small-diameter cylinder chamber that communicates with the
Formed between the stone part and the small diameter piston part,
A valve having an intermediate chamber connected to the output side of the hydraulic pressure control valve;
A valve body and the step provided in the valve body.
Spring that presses and biases a piston with a handle toward the large-diameter cylinder chamber.
And the intermediate piston formed on the stepped piston.
A communication hole communicating between the chamber and the small-diameter cylinder chamber;
The above-mentioned communication is performed by sliding the attached piston toward the small-diameter piston.
A check valve that acts in a direction to close the hole .