JPH10291470A - Antiskid brake control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antiskid brake control system requiring no motor-driven pump, made lightweight at a low cost, and reducing noises and kickback. SOLUTION: When a negative-pressure booster 4 is not operated, a solenoid selector valve 59 is set to the atmospheric air communication position 1, and a vacuum-driven pump 51 is not operated. When a pressure difference is generated between a variable-pressure chamber 24 and a constant-pressure chamber 23, the solenoid selector valve 59 is set to the vacuum communication position 11 to introduce a negative pressure, the vacuum-driven pump 51 is operated, and the brake fluid in the vacuum-driven pump 51 is discharged to a master cylinder(MCY) 5 side. When the pressure difference between both chambers 24, 23 is resolved, the solenoid selector valve 59 is again set to the atmospheric air communication position 1, the vacuum-driven pump 51 is not operated, and the brake fluid in a pump device 10 is sucked into the vacuum-driven pump 51. The vacuum-driven pump 51 is operated by the pressure difference between both chambers 24, 23, and the brake fluid in the sump device 10 is fed to the MCY 5 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle such as an automobile, which boosts the depression force of a brake pedal by a vacuum booster and eliminates the locking tendency when the wheels become locked during braking. Then, the brake fluid in the brake cylinder of the wheel is discharged to the low-pressure accumulator to reduce the pressure, and the discharged brake fluid in the low-pressure accumulator is returned to the master cylinder side to reduce and increase the brake pressure, thereby increasing the braking force. The present invention belongs to the technical field of an anti-skid brake control system (hereinafter, also referred to as ABS) that performs anti-skid control (hereinafter, also referred to as ABS control) for adjusting.

[0002]

2. Description of the Related Art A brake system for a vehicle such as an automobile is provided with a negative pressure booster for boosting a brake pedal depressing force to obtain a large brake pressure. Therefore, various brake systems including an ABS that performs ABS control when a brake wheel tends to lock have been proposed. One of such conventional ABSs
One is a return pump type ABS.

FIG. 7 is a diagram showing an example of a conventional brake system provided with a vacuum booster and a return pump type ABS. As is clear from FIG. 7, the brake system 1 is a two-system hydraulic brake system in which the front and rear wheels F and R are independent, and has an ABS 2 for each brake system. Among the components in each brake system, the same components are denoted by the same reference numerals.

In FIG. 7, 3 is a brake pedal, 4 is a negative pressure booster, and 5 is a tandem master cylinder (hereinafter referred to as M
CY), 6 is a reservoir for the master cylinder 5, 7 is a normally-open ABS control holding valve composed of a solenoid valve in which a communication position I and a shutoff position II are set, and 8 is a brake fluid passage to the master cylinder 5. , Wheel cylinders (hereinafter also referred to as W / C), 9 is a shut-off position
Normally closed A consisting of a solenoid valve with I and communication position II set
BS control pressure reducing valve, 10 is a sump device which is a low pressure accumulator, 11 is a motor driven ABS control pump (hereinafter also simply referred to as a pump), 12 is an ABS control holding valve 7, an ABS control pressure reducing valve 9 and a sump. An ABS control modulator 13 including a device 10 and a pump 11 is a proportioning valve (hereinafter, also referred to as PV) for reducing a rising gradient of a brake pressure when the rear wheel pressure is equal to or higher than a predetermined pressure.

FIG. 7 shows the brake system 1 only for the left front wheel _FL and the left rear wheel _RL.
Are provided in the same manner for each BS control modulator 12 is the right front wheel F _R and the right rear wheel R _R.

In the conventional hydraulic brake system 1 having the ABS 2, the pump 11 is stopped without being driven when the brake pedal 3 is not depressed and the brake is not operated. Both the ABS control pressure reducing valves 9 are set at the position I shown in the figure. Accordingly, the W / Cs 8 of the front and rear wheels F and R are both in communication with the reservoir 6 of the MCY 5, and no W / C pressure in the W / C 8, ie, no brake fluid pressure is generated.

At the time of normal braking by depressing the brake pedal 3, the input shaft 4a of the negative pressure booster 4 advances, and the control valve (not shown) of the negative pressure booster 4 is switched, so that the negative pressure booster is operated. Atmosphere is introduced into the transformer room. This allows
The negative pressure booster 4 operates to boost the pedal depression force to generate an output, and the MCY 5 is operated by the output. MCY5
Generates an MCY pressure, and this MCY pressure passes through the ABS control holding valve 7 on the front wheel brake system side, and the W / C 8
At the rear wheel brake system side, is sent to the W / C 8 through the ABS control holding valve 7 and the PV 13 to generate brake fluid pressure in each W / C 8, and the front and rear wheels F,
R is braked respectively. At this time, MCY
Both the pressure and the W / C pressure are high pressure boosted by the negative pressure booster 4.

When the brake is released by releasing the brake pedal 3, the negative pressure booster 4 and the MCY 5 are deactivated, the MCY pressure disappears, and the brake fluid pressure in each W / C 8 disappears. , R are both released.

During normal braking, when an electronic control unit (not shown) determines that at least one of the front and rear wheels F and R has a locking tendency, it shuts off the ABS control holding valve 7 in the ABS control modulator 12 of the front and rear wheels F and R. By setting the position to the position II, the brake fluid pressure in the W / C 8 is maintained at the brake fluid pressure at that time, and the locking tendency is suppressed from further strengthening. Further, when the electronic control unit determines that at least one of the wheels that tend to lock does not release the lock tendency even when the brake fluid pressure is maintained, the electronic control unit sets the ABS control pressure reducing valve 9 corresponding to the wheel to the communication position. II, and the brake fluid of W / C8 of the wheel is supplied to the sump device 10
And the brake fluid pressure of the W / C 8 is reduced, and the pump 11 corresponding to the wheel is driven.

When the wheel lock tendency is eliminated by the reduction of the brake fluid pressure and the wheel speed is recovered to some extent, the electronic control unit sets the ABS control pressure reducing valve 9 to the shut-off position I and sets the ABS control holding valve 7 To the communication position I. Thus, the hydraulic pressure from the pump 11 is supplied to the W / C 8 together with the MCY pressure, and the brake hydraulic pressure of the W / C 8 is increased again.

In this way, the electronic control unit operates the ABS control holding valve 7, the ABS control pressure reducing valve 9, and the pump 11
Control of the brake fluid pressure,
ABS control by pressure reduction and pressure increase is performed until the tendency to lock the wheels is completely eliminated.

[0012]

By the way, in the brake system 1 provided with such an ABS 2, AB
High S / C boosted by negative pressure booster during S control decompression
Since the pressure is reduced, the amount of the brake fluid discharged to the sump device 10 increases. Then, the low-pressure brake fluid discharged to the sump device 10 is returned to the MCY pressure side considerably higher than the brake fluid, so that the pump 11 has a large capacity as a return pump (for example, 25 MPa; 2 cc / sec) is required.
In addition, a motor for driving such a large-capacity pump requires a large-capacity motor, which causes not only an extremely large weight but also a high cost and a high noise level. Also, since the pump 11 returns the brake fluid of the sump device 10 to the high MCY pressure side, kickback to the brake pedal 3 increases,
There was also a problem that pedal feeling was bad.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the weight and cost by eliminating the need for a motor-driven pump and to reduce both noise and kickback. It is to provide a brake control system.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention provides a brake operating member, a constant-pressure chamber in which a negative pressure is constantly introduced, and a non-operating negative pressure in which a negative pressure is introduced and activated. A variable pressure chamber into which atmospheric pressure is introduced, and a control valve is operated by operation of the brake operating member to introduce air into the variable pressure chamber, thereby boosting the operating force of the brake operating member and outputting the same. Negative pressure booster, a master cylinder that operates by the output of the negative pressure booster to generate a master cylinder pressure, a brake cylinder that receives the master cylinder pressure to generate a braking force, and a brake cylinder A low-pressure accumulator from which the brake fluid is discharged, a normally-open first solenoid on-off valve for controlling the introduction of the atmosphere to the negative pressure booster, and a direct communication between the constant-pressure chamber and the variable-pressure chamber and control of shut-off Normally closed A second electromagnetic on-off valve, a normally open third electromagnetic on-off valve provided in a passage connecting the master cylinder and the brake cylinder, and controlling communication and shutoff of these two cylinders; A normally-closed fourth electromagnetic on-off valve that is provided in a passage connecting an accumulator and controls communication and disconnection between the brake cylinder and the low-pressure accumulator, and the variable-pressure chamber and the constant-pressure chamber of the negative pressure booster; It operates according to the pressure difference of
A vacuum drive pump that sucks in the brake fluid of the low-pressure accumulator and discharges the brake fluid from the third solenoid on-off valve to the master cylinder side, and further controls the introduction and discharge of negative pressure and atmospheric pressure to and from the vacuum drive pump. An electromagnetic switching valve, wherein the vacuum drive pump discharges the brake fluid to the master cylinder side when the negative pressure is introduced by the electromagnetic switching valve, and the negative pressure is discharged by the electromagnetic switching valve. When atmospheric pressure is introduced, the low pressure accumulator is set so as to suck the brake fluid.

The invention according to claim 2 is characterized in that the electromagnetic switching valve is controlled to be switched in accordance with the pressure difference between the variable pressure chamber and the constant pressure chamber of the negative pressure booster. Furthermore, the invention according to claim 3 is characterized in that the vacuum drive pump has a constant pressure chamber in which atmospheric pressure is constantly introduced and an atmospheric pressure from the electromagnetic switching valve is introduced when not operating and a negative pressure from the electromagnetic switching valve is introduced when operating. A diaphragm made of rubber for partitioning the pressure chamber, a diaphragm plate abutting on the surface of the diaphragm on the side of the pressure chamber, and one end of the diaphragm abutting on the diaphragm plate, to operate the diaphragm and the diaphragm plate. A pump piston that sucks and discharges the brake fluid by reciprocating in conjunction therewith, wherein the central portion of the diaphragm is formed in a cylindrical block shape, and the vacuum drive pump is provided in the central portion of the cylindrical block shape. A projection is formed which can abut on a housing defining a constant pressure chamber of the diaphragm plate, and the diaphragm plate has A cylindrical bulging portion bulging to the side opposite to the diaphragm side is formed, and a cylindrical block-shaped center portion of the diaphragm fits into a concave portion formed on the diaphragm side of the diaphragm plate by the cylindrical bulging portion. The diaphragm and the diaphragm plate are always urged toward the constant pressure chamber of the vacuum drive pump by a return spring contracted in the variable pressure chamber of the vacuum drive pump.

According to a fourth aspect of the present invention, an annular retainer having a hole at the center is interposed between the return spring and the diaphragm plate, and an inner peripheral edge of the retainer is inclined toward the diaphragm plate. And the pump piston and the retainer are integrally connected by penetrating one end of the pump piston through a hole of the retainer from the side opposite to the diaphragm plate to the diaphragm plate side. It is characterized by being done.

[0017]

According to the present invention thus constructed, AB
During the S control, the vacuum drive pump is driven by the electromagnetic switching valve according to the pressure difference between the variable pressure chamber and the constant pressure chamber of the negative pressure booster, and the brake discharged from the brake cylinder to the low pressure accumulator when the ABS control is depressurized. The liquid is supplied to the MCY side from the third solenoid on-off valve. As described above, since the brake fluid discharged from the W / C is returned to the MCY side, the amount of the brake fluid sent from the MCY to the W / C is reduced, and the low-pressure accumulator can be reduced.

Further, in the ABS of the present invention, since the vacuum drive pump and the electromagnetic switching valve are used as described above, the conventional motor drive pump and its motor are not required. Therefore, the weight of the ABS control pump is reduced, the cost is reduced, and the noise is reduced.

According to the second aspect of the present invention, since the vacuum drive pump is driven and controlled in accordance with the pressure difference of the negative pressure booster, when the brake fluid is returned to the MCY side by the vacuum drive pump, the brake operation is performed. The kickback to the member is reduced, and the operation feeling is improved.

Further, according to the third aspect of the present invention, there is no need for a holder which is provided at the center of the diaphragm to provide an operating force to the pump piston and a screw for fixing the diaphragm to the holder, which are components of the power piston. Therefore, the number of parts is reduced and the structure is simplified,
Assembling becomes easy. This reduces the cost of the vacuum drive pump.

Further, according to the present invention, the power piston is urged through the retainer by the return spring contracted in the variable pressure chamber of the vacuum drive pump, and the retainer is driven by the teeth on the inner peripheral edge of the retainer. And the pump piston are integrally connected, so that a return spring for urging the pump piston to the inoperative position is not required. This shortens the overall length of the vacuum drive pump and eliminates the need for a spring case for supporting this return spring.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing an example of an embodiment of an anti-skid brake control system according to the present invention. The same components as those of the conventional anti-skid brake control system shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, the ABS 2 of the present embodiment includes a normally open first solenoid on-off valve 14 for controlling the introduction of the atmosphere into the negative pressure booster 4, and a power piston of the negative pressure booster 4. Normally closed second solenoid on-off valve 1 for controlling communication and shutoff between the chambers on both sides of the valve
5 are provided. The vacuum booster 4 will be described in detail. As shown in FIG. 2, the vacuum booster 4 includes a front shell 16 and a rear shell 17 that are connected to each other by, for example, bayonet coupling.

A valve body 18 is disposed so as to penetrate the rear shell 17 between a space formed by the front shell 16 and the rear shell 17 and a space outside the space. Rear shell 1
It is airtightly and slidably supported by the seal member 7 and the seal member 19. The valve body 18 has two shells 16, 1
The power piston member 20 arranged in the space inside 7 is connected. A diaphragm 21 is provided between the shells 16 and 17 and the valve body 18 on the back of the power piston member 20. A power piston 22 is formed by the power piston member 20 and the diaphragm 21. The power piston 22 allows the two shells 16,
The space inside 17 is divided into a constant pressure chamber 23 and a variable pressure chamber 24.

The valve body 18 is formed with a concave fitting portion 25 which opens into the constant pressure chamber 23. The bottom of the concave fitting portion 25 has a central portion protruding toward the constant pressure chamber 23 side.
a is formed. A first hole 26 that opens to the concave fitting portion 25 is formed substantially at the center of the protruding portion 18a, and the rear portion (right side in the drawing) is continuous with the first hole 26.
A second hole 27, a third hole 28, a fourth hole 29, and a fifth hole 30 opening at the rear end of the valve body 18 are formed in this order. Further, an axial passage 31 communicating the constant pressure chamber 23 and the fourth hole 29 is formed in the valve body 18.

A valve plunger 32 is slidably fitted in the first hole 26 and the second hole 27 of the valve body 18. An input shaft 4a linked to a brake pedal (not shown) is connected to the right end of the valve plunger 32. A radial hole 33 is formed in the valve body 18 so as to be orthogonal to the second hole 27, and a key member 34 is fitted through the hole 33 to the valve plunger 32 so as to be relatively movable in the axial direction. ing. The key member 34 can move in the axial direction by the width of the hole 33 together with the valve plunger 32, and the key member 34 prevents the valve plunger 32 from coming out of the valve body 18. Further, a passage 35 is formed in the valve body 18 so as to open to the variable pressure chamber 24 so as to be orthogonal to the second hole 27. This passage 35 also communicates with the third hole 28.

A control valve 36 is provided in the fifth hole 30 of the valve body 18. The control valve 36 is attached to the valve body 18 and is constantly urged in the direction of the valve plunger 32 by a resilient force of a spring 37 interposed between the control valve 36 and the input shaft 4a. A first valve seat 39 formed on the right end of the valve body and a second valve seat 40 formed on the valve body 18. This control valve 36
Means that the valve body 38 is seated on the first valve seat 39 and the second valve seat 40
When the valve is disengaged from the first valve seat 39, the communication between the constant pressure chamber 23 and the variable pressure chamber 24 and the communication between the variable pressure chamber 24 and the atmosphere are interrupted.
When seated on the valve seat 40, the constant pressure chamber 23 and the variable pressure chamber 2
The switching control is performed so as to cut off the communication with the pressure chamber 4 and to connect the variable pressure chamber 24 with the atmosphere. Therefore, the valve body 38 and the first valve seat 39 constitute an atmosphere valve for controlling the introduction of the atmosphere, and the valve body 38 and the second valve seat 40 constitute a vacuum valve for controlling the introduction of the vacuum. ing.

A large-diameter portion on the right end of the output shaft 41 is provided in the concave fitting portion 25 of the valve body 18. The concave portion formed in the large-diameter portion on the right end slides on the projecting portion 18 a of the valve body 18. They are freely fitted. A reaction disk 42 is housed in the concave portion of the right end large diameter portion between the projection 18 a of the valve body 18 and the output shaft 41. A predetermined gap is interposed between the valve plunger 32 and the reaction disk 42.

The output shaft 41 is prevented from coming out of the valve body 18 by a retainer 44 urged rightward by a return spring 43 for returning the valve body 18 to the inoperative position. Further, the left end of the output shaft 41 is interlocked with a primary piston 5a (shown in FIG. 1) of the master cylinder 5 attached to the front shell 16.

The valve body 18 and each of the power pistons 22 connected thereto are normally held in an inoperative position shown by a return spring 43. In this non-operating state, the key member 34 abuts against the inner surface of the rear shell 17 to regulate the rightward movement of the valve plunger 32 and hold the valve plunger 32 at the retreat limit position. And
When the input shaft 4a is not actuated, the key member 34 is at a position advanced with respect to the valve body 18, and at this time, the valve body 38 is seated on the first valve seat 39, and is slightly different from the second valve seat 40. The gap is maintained, and the variable pressure chamber 24 is isolated from the atmosphere and communicates with the constant pressure chamber 23. Therefore, at the time of braking, as soon as the valve plunger 32 is actuated by the advancement of the input shaft 4a, the valve body 38 is seated on the second valve seat 40, separated from the first valve seat 39, and communicates with the variable pressure chamber 24 and the atmosphere. Are immediately in communication.

The constant-pressure chamber 23 is always in communication with a vacuum source 46 (shown in FIG. 1) such as an intake manifold of an engine via a negative pressure introducing pipe 45 attached to the front shell 16. Therefore, a negative pressure is always introduced into the constant pressure chamber 23.

The rear shell 17 is further formed with a cylindrical projecting portion 17a projecting rearward.
A hermetic boot 46 made of an elastic material such as rubber is provided between the input shaft 7a and the input shaft 4a so as to completely cover the rear end of the valve body 18 and seal the inside. The first air introduction passage 47 is formed in the boot 46, and the first air introduction passage 47 and the fifth air introduction passage 47 are provided between the inner peripheral surface of the boot 46 and the outer peripheral surface of the rear end of the valve body 18. Annular second air supply passage 48 communicating with the hole 30
Are formed. The first air introduction passage 47 is capable of communicating with the atmosphere via a third air introduction passage 49. In the third air introduction passage 49, a communication position I and a cutoff position II are set. An open first solenoid on-off valve 14 is provided.

The constant-pressure chamber 23 and the variable-pressure chamber 24 can communicate with each other through an inter-chamber communication passage 50. In the inter-chamber communication passage 50, a cutoff position I and a communication position II are set. The above-mentioned normally closed second electromagnetic on-off valve 15 is provided.

Further, the ABS 2 is provided with a vacuum drive pump 51. As shown in FIG. 3, the vacuum drive pump 51 includes a first housing 5 made of a thin plate.
2 and a second housing 53 in the form of a cylinder block. The first and second housings 52, 53 are connected to each other with a power piston 54 interposed therebetween. The power piston 54 includes an annular rubber diaphragm 54 a having an outer peripheral edge interposed between the first and second housings 52 and 53,
An annular diaphragm plate 5 arranged on the back of 4a
4b penetrate through the holes of these annular diaphragm 54a and diaphragm plate 54b and
A holder 54d for fixing and supporting the inner peripheral edges of the 4a and 54b with screws 54c, and a rubber member 54e fixed to the holder 54d and preventing a collision sound when the holder 54d contacts the first housing 52. I have.

The space formed between the first and second housings 52 and 53 is airtightly partitioned into a constant pressure chamber 55 and a variable pressure chamber 56 by the power piston 54. The constant pressure chamber 55 is communicated with the atmosphere through a hole 57 formed in the first housing 52 and is always maintained at the atmospheric pressure. The variable pressure chamber 56 is formed in the second housing 53. Through the passage hole 58, the electromagnetic switching valve 5
9 is always in communication. The electromagnetic switching valve 59 is connected to an atmosphere communication position I that communicates the transformation chamber 56 with the atmosphere,
The vacuum source 46 and the constant pressure chamber 23 of the negative pressure booster 4
Is set to a vacuum communication position II that communicates with
At the time of non-operation, it is set to the illustrated atmosphere communication position I and communicates the transformation chamber 56 with the atmosphere. And this electromagnetic switching valve 59 is
When the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 of the negative pressure booster 4 is equal to or larger than a predetermined value, the electronic control unit of the ABS 2 switches to the vacuum communication position II. Therefore, the operation of the vacuum drive pump 51 is controlled according to the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 of the negative pressure booster 4.

A stepped cylinder hole 60 is formed in the second housing 53 so as to penetrate in the axial direction. In the cylinder hole 60, a stepped pump piston 61 is slidable in a liquid-tight manner. Is provided. One end of the pump piston 61, that is, the large-diameter end, is supported in contact with the concave portion of the pump piston holding portion 54f provided at the center of the holder 54d of the power piston 54, and the other end, that is, the small-diameter end. Project out of the second housing 53. A spring force of a return spring 63 supported by a spring case 62 fixed to the second housing 53 is constantly applied to the other end of the pump piston 61 via a retainer 64, so that the pump piston 61 is not operated at all times. Direction (rightward in FIG. 3). When the vacuum drive pump 51 is not operating, the pump piston 61 is set to the inoperative position shown in FIG. 3, and at this time, the rubber member 54e of the power piston 54 abuts on the first housing 52, and the pump piston 61 is moved to the right end. Position.

Further, on the small diameter side of the pump piston 61,
An O-ring 65 for sealing between the small diameter side of the pump piston 61 and the large diameter side of the cylinder bore 60;
An O-ring 66 is provided for sealing between the small diameter side of the cylinder bore 1 and the small diameter side of the cylinder hole 60.

Further, two Os
A suction hole 67 and a discharge hole 68 are formed in a direction orthogonal to the cylinder hole 65 so as to open to the large diameter side of the cylinder hole 60 between the rings 65 and 66. The suction hole 71 is communicated with the sump device 10.
A suction-side check valve 69 that allows only the flow of the brake fluid toward the suction port is provided. In addition, the discharge hole 68 is M
The discharge hole 68 is provided with a discharge-side check valve 70 that allows only the flow of the brake fluid from the cylinder hole 61 to the MCY 5.

In the rightmost position of the pump piston 61, an annular chamber 71 formed between the large diameter side of the cylinder hole 60 and the small diameter side of the pump piston 61 between the two O-rings 65 and 66 has a maximum volume. Has become. When the power piston 54 advances due to the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56, the pump piston 61 advances to reduce the volume of the annular chamber 71 and generate a discharge pressure in the annular chamber 71.
In that case, the power piston 54 and the pump piston 6
1 is set so that the discharge pressure becomes larger than the MCY pressure of the MCY 5 generated at that time by the output of the negative pressure booster 4.
At the time of forward movement of 1, the brake fluid in the annular chamber 71 is discharged to the MCY5 side. The other brake system is the same as the above-mentioned one brake system, so that illustration and description thereof are omitted.

Next, the operation of the brake system 1 having the ABS 2 of this embodiment will be described. Negative pressure booster 4
Is in the inoperative position shown in the figure, the valve body 38 of the control valve 36 is seated on the first valve seat 39, maintains a slight gap with the second valve seat 40, and the atmosphere valve is closed. In the state, the vacuum valve is in the open state. Therefore, since both the constant pressure chamber 23 and the variable pressure chamber 24 have a negative pressure, the negative pressure booster 4 does not operate.

The first solenoid on-off valve 14 is set at the communication position I to communicate the third air supply passage 49 to the atmosphere, and the second solenoid on-off valve 15 is set at the shut-off position I to set the space between the rooms. The connection passage 50 is shut off. Therefore, the fifth hole 3
0 communicates with the atmosphere via a second air supply passage 48, a first air supply passage 47, a third air supply passage 49, and an open first electromagnetic on-off valve 14, and a constant pressure chamber of the negative pressure booster 4. 23 and the transformation chamber 24 do not communicate with each other via the inter-room connection passage 50. Further, the ABS control holding valve 7 is set at the communication position I, and the ABS control pressure reducing valve 9 is set at the cutoff position I. Further, since the electromagnetic switching valve 59 is set at the atmosphere communication position I and the constant pressure chamber 55 and the variable pressure chamber 56 of the vacuum drive pump 51 are both at atmospheric pressure, the vacuum drive pump 51 does not operate.

In this state, when the brake pedal 3 is depressed and a normal brake operation is performed, the input shaft 4a moves forward toward the valve body 18. As the input shaft 4a advances, the valve plunger 32 moves forward with respect to the key member 34 and the valve body 18, and the valve body 38 of the control valve 36 is seated on the second valve seat 40, and the valve body 38 One valve seat 39 is released, and the vacuum valve closes and the atmosphere valve opens.
Accordingly, the atmosphere communicating with the fifth hole 30 flows into the variable pressure chamber 24 through the gap between the valve body 38 and the first valve seat 39, the third hole 28, and the passage 35.

Since a pressure difference is generated between the variable pressure chamber 24 and the constant pressure chamber 23 due to the atmosphere flowing into the variable pressure chamber 24, the power piston 22 operates and the valve body 18 moves forward.
The negative pressure booster 4 generates an output from the output shaft 41, and the pistons 5a and 5b of the MCY 5 are operated and the MCY
Generate pressure. This MCY pressure is supplied to the W / C 8 through the first solenoid on-off valve 7 in the same manner as in the above-described conventional case, and the normal brake is operated. At this time, the MCY pressure is prevented from being supplied to the annular chamber 71 of the vacuum drive pump 51 by the check valve 70.

When the valve body 38 is seated on the first valve seat 39 and the atmosphere valve is closed, the atmosphere stops flowing into the variable pressure chamber 24,
The advance of the valve body 18 stops. Thus, the negative pressure booster 4 generates a boosted output at a predetermined servo ratio corresponding to the input.

The variable pressure chamber 24 and the constant pressure chamber 23 of the negative pressure booster 4
When the pressure difference between the pressure and the pressure becomes equal to or more than the predetermined value, the electronic control unit switches the electromagnetic switching valve 59 to the vacuum communication position II.
The transformation chamber 56 of the vacuum drive pump 51 is shut off from the atmosphere and is connected to the vacuum source 46. Therefore, a vacuum is introduced into the variable pressure chamber 56, a pressure difference is generated between the variable pressure chamber 56 and the constant pressure chamber 55, and the power piston 54 is operated, and the pump piston 61 moves forward. Occur. When the pressure in the annular chamber 71 becomes larger than the MCY pressure at that time, the annular chamber 7
1 brake fluid passes through check valve 70
And the first solenoid on-off valve 7. At this time, the brake fluid in the annular chamber 71 is supplied to the check valve 6.
9 prevents it from flowing towards the sump device 10.

When the brake pedal 3 is released, the input shaft 4
a is retracted, and the valve plunger 32 is
4 is relatively retracted with respect to the valve body 18 until the 4 comes into contact with the rear surface of the hole 33. When the valve plunger 32 is retracted, the valve body 38 is separated from the second valve seat 40 and the vacuum valve is opened, and the air introduced into the variable pressure chamber 24 passes through the passage 35, the third hole 28, the valve body 38 and the 2 through the gap with the valve seat 40, the passage 31, the constant pressure chamber 23 and the negative pressure introducing pipe 45.
6, the pressure in the transformer room 24 decreases, and the transformer room 2
The pressure difference between the pressure chamber 4 and the constant pressure chamber 23 is almost eliminated. Thus, the spring force of the return spring 43 causes the valve body 18
And the power piston 22 are retracted, and the negative pressure booster 4 shown in FIG. Therefore, MC
Y5 is also deactivated, the brake fluid pressure of W / C8 disappears, and the normal brake is released.

At this time, since the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 becomes lower than a predetermined value, the electronic control unit switches the electromagnetic switching valve 59 to the atmosphere communication position I. Therefore, the atmosphere is introduced into the variable pressure chamber 56 of the vacuum drive pump 51 through the electromagnetic switching valve 59 and the passage hole 58, and the negative pressure in the variable pressure chamber 56 disappears.
And the pressure difference disappears. Thereby, the pump piston 61 and the power piston 54 are both retracted by the spring force of the return spring 63, the rubber member 54e abuts on the first housing 52, and the vacuum drive pump 51 is also in a non-operating state. When the pump piston 61 retreats, the volume of the annular chamber 71 increases, so that the brake fluid is sucked from the sump device 10 into the annular chamber 71 via the check valve 69. The power piston 54
The rubber member 54e abuts on the first housing 52, so that noise at the time of abutment is prevented.

When the electronic control unit detects at least one locking tendency of the wheels during braking by the operation of the negative pressure booster 4, as in the case of the conventional general ABS control, the first and second solenoid on-off valves 14 , 15 are turned on to close the first solenoid on-off valve 14 and open the second solenoid on-off valve 15. Therefore, the fifth hole 30 is shielded from the atmosphere, and the variable pressure chamber 24 communicates with the constant pressure chamber 23 via the inter-room connection passage 50 and the open second electromagnetic switching valve 15. As a result, the air in the variable pressure chamber 24 flows toward the constant pressure chamber 23, so that the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 is reduced, the output of the negative pressure booster 4 is reduced, and the M
The CY pressure, that is, the W / C8 brake pressure is reduced. At this time, the air in the constant pressure chamber 55 of the vacuum drive pump 51 also flows through the variable pressure passage 57 toward the constant pressure chamber 23 of the negative pressure booster 4.

At this time, the output of the negative pressure booster 4 is reduced, so that the valve body 18 is retracted, and the valve body 38 is moved to the first valve seat 3.
9. Separate from 9 and open the air valve. However, since the fifth hole 30 is shielded from the atmosphere, the air in the cab does not flow into the variable pressure chamber 24 even when the atmosphere valve is opened, and the output of the negative pressure booster 4 does not increase.

Further, since the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 of the negative pressure booster 4 becomes smaller and lower than a predetermined value, similarly, the constant pressure chamber 55 of the vacuum drive pump 51
The pressure difference between the pressure change chamber 56 and the pressure change chamber 56 also becomes small, and the electromagnetic switching valve 59, which has been switched to the valve communication position II by the operation of the negative pressure booster 4, is switched to the atmosphere communication position I. Therefore, the pump piston 61 and the power piston 54 are respectively retracted, and the brake fluid is sucked into the annular chamber 71 from the sump device 10 via the check valve 69 as described above.

When the brake pressure is reduced due to the decrease in output of the negative pressure booster 4, the tendency of the wheels to be locked does not disappear, and if further reduction is required, the electronic control unit shuts off the ABS control holding valve 7. At the same time as the position II, the pressure reducing valve 9 for ABS control is set at the communication position II. Thereby, W /
C8 is cut off from MCY5 and sump device 10
The brake fluid in the W / C 8 is communicated with the sump device 10.
And the brake pressure of the W / C 8 is further reduced.

When the wheel speed recovers to a predetermined speed due to the reduction of the brake pressure, the electronic control unit sets the ABS control holding valve 7 to the communication position I, the ABS control pressure reducing valve 9 to the cutoff position I, The electromagnetic on-off valve 14 is set at the communication position I, and the second electromagnetic on-off valve 15 is set at the shut-off position I.

Therefore, the fifth hole 30 communicates with the atmosphere again, and the variable pressure chamber 24 is cut off from the constant pressure chamber 23 through the inter-room connection passage 50. Further, the W / C 8 communicates with the MCY 5 and shuts off the sump device 10. As a result, the flow of the air in the variable pressure chamber 24 to the constant pressure chamber 23 is stopped, and the air again flows into the variable pressure chamber 24. Therefore, the output of the negative pressure booster 4 increases, and the brake pressure increases. Is increased. At this time, when the pressure difference between the variable pressure chamber 24 and the constant pressure chamber 23 increases to a predetermined value or more, the electromagnetic switching valve 59 is switched to the valve communication position II as described above. Will be introduced again. Thereby, the power piston 54 and the pump piston 61 of the vacuum drive pump 51 also advance again, and the brake fluid in the annular chamber 71 is discharged to the passage between the MCY 5 and the ABS control holding valve 7.

In this manner, the electronic control unit operates the ABS control holding valve 7 until the locking tendency of the wheels is completely eliminated.
ABS control pressure reducing valve 9, first and second solenoid on-off valves 1
By repeatedly controlling on / off of 4,15,
ABS that repeats pressure reduction control and pressure increase control of brake pressure
Perform control. Each time the pressure reduction and pressure increase control is repeated, the brake fluid of the sump device 10 discharged from the W / C 8 is returned to the MCY 5 again.

According to the ABS 2 of this embodiment, since the vacuum drive pump 51 is used, the motor drive pump 11 and its motor, which are heavy and costly and have high noise, as in the prior art shown in FIG. Becomes unnecessary.
Therefore, the weight of the ABS control pump is reduced, the cost is reduced, and the noise is further reduced.

Since the vacuum drive pump 51 is driven and controlled in accordance with the pressure difference between the two chambers 23 and 24 of the negative pressure booster 4, when the vacuum drive pump 51 returns the brake fluid to the MCY 5 side, The kickback to the brake pedal 3 is reduced, and the pedal feeling is improved.

Further, since the brake fluid discharged from the W / C 8 is returned to the MCY 5, the amount of the brake fluid to be sent from the MCY 5 to the W / C 8 can be reduced, and the sump device 10 can be reduced in size. it can.

FIG. 4 is a view similar to FIG. 3, partially showing a vacuum drive pump 51 according to another embodiment of the present invention. The same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 4, the vacuum drive pump 51 of this embodiment includes a variable pressure chamber 56 and the second housing 53 of the above-described example, a housing shell 53a defining the variable pressure chamber 56, and a pump. The piston 61 is slidably fitted, and the annular chamber 71, the suction hole 67, the discharge hole 68
And a housing block 53b provided with both check valves 69 and 70.

The diaphragm 54a of the power piston 54 is formed in a disk shape instead of an annular shape as in the above-described example.
It has a cylindrical block shape protruding to the side. On the surface of the central portion 54g facing the first housing 52, a projection 54h for preventing the generation of a collision sound when contacting the first housing 52 is formed.
A substantially hemispherical concave portion 54i is formed on the surface of the g in the pressure transformation chamber 56 side. Furthermore, the diaphragm plate 54b also
As in the above-described example, it is formed in a disk shape instead of an annular shape, and has a central portion formed as a cylindrical bulging portion 54j bulging toward the transformation chamber 56 side. The central portion of the cylindrical bulging portion 54j is a spherical bulging portion 54k that bulges substantially hemispherically toward the constant pressure chamber 55 side.

The block-shaped central portion 54g of the diaphragm 54a is fitted into the concave portion of the cylindrical bulging portion 54j of the diaphragm plate 54b. In that case,
The surface of the center portion 54g of the diaphragm 54a on the side of the transformation chamber 56 is in contact with the inner surface of the concave portion of the cylindrical bulging portion 54j over substantially the entire surface.

Transformation chamber 56 of diaphragm plate 54k
On the side, an annular retainer 72 is provided so as to surround the cylindrical bulging portion 54j.
A return spring 73 is contracted between the housing 2 and the housing shell 53a. Therefore, the power piston 54 is constantly urged in the non-operation direction (rightward in FIG. 4) by the spring force of the return spring 73. The inner peripheral edge of the retainer 72 has a diaphragm plate 54b
A predetermined number of teeth 72a inclined to the side are formed, and an annular concave portion 61a is formed at the spherical rear end of the pump piston 61. And the pump piston 61
When the spherical rear end is inserted into the center hole of the retainer 72 from the left side in the figure, the spherical rear end is inserted while elastically deforming the teeth 72a. When the annular concave portion 61a comes to the position of the teeth 72a, the teeth 72a Is restored by elasticity and the teeth 72a
Of the pump piston 6 enters the annular concave portion 61a.
1 and the retainer 72 are integrally connected. A rubber member 74 is fixed to a surface of the retainer 72 facing the housing shell 53a, and the retainer 72 is attached to the housing shell 53 by the rubber member 74.
The impact force and the collision sound when abutting on a are reduced.

The center 54g of the diaphragm 54a
Is merely fitted in the concave portion of the cylindrical bulging portion 54j of the diaphragm plate 54b, but when the vacuum drive pump 51 is not operated, the central portion 54g of the diaphragm 54a and the cylindrical bulge of the diaphragm plate 54b are not fitted. The projection 54j is sandwiched between the retainer 72 and the first housing 52 by the spring force of the return spring 73, and during operation, the central portion 54g is caused by the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56. It is configured to be prevented from coming off from the cylindrical bulging portion 54j. But the central part 5
In order to surely prevent the 4 g from coming off from the cylindrical bulging portion 54j, a projection is provided on the diaphragm 54a, and this projection is pressed into a hole formed in the diaphragm plate 54b to press the diaphragm 54a and the diaphragm plate 5 with each other.
4b may be fixed, or the diaphragm 54
a and the diaphragm plate 54b may be joined by an adhesive.

The housing shell 53a is provided with a hole 75 corresponding to the passage hole 58 of the above-described example. Through this hole 75, the variable pressure chamber 56 is connected to the electromagnetic switching valve 59. Other configurations of the vacuum drive pump 51 and the brake system 1 in this example are the same as those in the above-described example.

In the ABS 2 of the present embodiment thus constructed, the electromagnetic switching valve 59 is in the atmosphere communication position I and the vacuum drive pump 51 is not operated so that the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56 does not occur. At this time, the vacuum drive pump 51 is in the illustrated state, and the projection 54h is in contact with the first housing 52 by the spring force of the return spring 73.

The variable pressure chamber 23 and the constant pressure chamber 24 of the negative pressure booster 4
When the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56 is changed to a predetermined value, the electromagnetic switching valve 59 is switched to the vacuum communication position II, and the vacuum 54 and the pump piston 61 move forward, and the brake fluid in the annular chamber 71 becomes MCY.
5 is discharged. The transformation chamber 2 of the negative pressure booster 4
When the pressure difference between the pressure chamber 3 and the constant pressure chamber 24 drops below a predetermined value, the electromagnetic switching valve 59 is switched to the atmosphere communication position I, air is introduced into the variable pressure chamber 54, and the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56 is changed. Is resolved, the power piston 54 retreats toward the inoperative position via the retainer 72 by the spring force of the return spring 73. Since the retainer 72 and the pump piston 61 are integrated, the pump piston 61 also retreats in conjunction with the retraction of the retainer 72, and the sump device 1
Zero brake fluid is sucked into the annular chamber 71.

According to the vacuum drive pump 51 of this example, the screw 54c and the holder 54d of the example of FIG. 3 are different from the vacuum drive pump 51 of the example shown in FIG.
Is unnecessary, the number of parts is reduced, the structure is simplified, and assembly is facilitated. Thereby, the cost of the vacuum drive pump 51 is reduced.

The vacuum drive pump 51 of this example
According to the description, the return spring 73 is
4 and a retainer 72 and a housing shell 53 a
And the retainer 72 and the pump piston 61 are integrally connected by the teeth 72a on the inner peripheral edge of the retainer 72.
The return spring 63 as shown in the example of FIG. This shortens the overall length of the vacuum drive pump 51 and eliminates the need for the spring case 62. Other functions and effects of the brake system 1 of this example are the same as those of the above-described example.

FIG. 5 is a view similar to FIG. 1 schematically showing still another example of the embodiment of the present invention, and FIG. 6 is a sectional view of a pilot valve used in this example. is there.
Note that the same components as those in the above-described respective examples are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the ABS 2 shown in FIG. 1 described above, the vacuum drive pump 51 and the electromagnetic switching valve 59 are directly connected. However, the ABS 2 in this example has the vacuum driving pump 51 and the electromagnetic switching valve 59 as shown in FIG. A pilot valve 76 composed of a relay valve is provided between the pilot valve 76 and the solenoid valve 59. The negative pressure from the electromagnetic switching valve 59 acts as a pilot pressure for controlling the operation of the pilot valve 76, and the pilot valve 76 Negative pressure is introduced into the vacuum drive pump 51 through 76 without passing through the electromagnetic switching valve 59.

As shown in FIG.
Is provided with a diaphragm piston 80 which partitions a constant pressure chamber 78 and a variable pressure chamber 79 in a housing 77. The transformation chamber 79 is connected to the electromagnetic switching valve 51, and the electromagnetic switching valve 5
Atmosphere is introduced at the atmosphere communication position I, and negative pressure is introduced at the vacuum communication position II, and the constant pressure chamber is always in communication with the atmosphere. In addition, the housing 77 is always in communication with the vacuum source 46 and the constant pressure chamber 23 of the negative pressure booster 4 and the inlet 8 through which the negative pressure is constantly introduced.
1 and an outlet 82 that constantly communicates with the vacuum drive pump 51 and guides the negative pressure from the inlet 81 to the vacuum drive pump 51.

A normally open negative pressure discharge valve 83 is provided in a passage between the constant pressure chamber 78 and the outlet 82, and a normally closed negative pressure outlet is provided in a passage between the inlet 81 and the outlet 82. A pressure introduction valve 84 is provided. The negative pressure discharge valve 83 includes a first valve seat 85 provided in the housing 77 and a discharge valve 86 that can be seated on the first valve seat 85.
4 includes a second valve seat 87 provided on the housing 77 and an introduction valve body 88 that can be seated on the second valve seat 87. The two valve bodies 86 and 88 are provided integrally, and their opening and closing are controlled by a pump piston 89 connected to the diaphragm piston 80. In this case, when the pilot valve 76 is not operated, the atmospheric pressure is introduced into the variable pressure chamber 79 and the constant pressure chamber 78
The pressure difference between the pressure chamber 79 and the pressure change chamber 79 does not occur, so that the pump piston 89 moves downward by the spring force of the return spring 90, and the introduction valve body 88 is seated on the second valve seat 87 as shown in FIG. When the body 86 is separated from the first valve seat 85 and the pilot valve 76 is operated, a negative pressure is introduced into the variable pressure chamber 79 to generate a pressure difference between the constant pressure chamber 78 and the variable pressure chamber 79. The pressure difference causes the diaphragm piston 80 to bend upward and the pump piston 89 to move upward, so that the introduction valve body 88 is separated from the second valve seat 87 and the discharge valve body 86 is seated on the first valve seat 85. Has become.

The vacuum drive pump 51 of this example
Uses a vacuum drive pump 51 shown in FIG. Other configurations of the ABS 2 of this example are the same as those of the above-described examples.

In the ABS 2 thus constructed, when the electromagnetic switching valve 59 is at the atmospheric communication position I, the atmospheric pressure is introduced into the variable pressure chamber 79 of the pilot valve 76 and the constant pressure chamber 78 and the variable pressure chamber When the pressure difference from the pressure pump 79 does not occur, the pilot valve 76 is in a non-operating state in which the negative pressure discharge valve 83 shown in FIG. 5
6 is introduced. Therefore, the vacuum drive pump 5
The pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56 does not occur, the vacuum drive pump 51 is also in the non-operating state shown in the drawing, and the projection 54h is in contact with the first housing 52 by the spring force of the return spring 73. It has become.

The variable pressure chamber 23 and the constant pressure chamber 24 of the negative pressure booster 4
Is greater than or equal to a predetermined value, the electromagnetic switching valve 59 is switched to the vacuum communication position II, and the pilot valve 7
6, when a negative pressure is introduced into the variable pressure chamber 79 and a pressure difference is generated between the constant pressure chamber 78 and the variable pressure chamber 79, the negative pressure discharge valve 83 is closed and the negative pressure introduction valve 84 is opened to operate the pilot valve 76. The negative pressure is introduced into the transformation chamber 56 of the vacuum drive pump 51. Therefore, a pressure difference occurs between the constant pressure chamber 55 and the variable pressure chamber 56 of the vacuum drive pump 51, and the vacuum drive pump 51 also operates, and the brake fluid in the annular chamber 71 is discharged to the MCY5 side.

When the pressure difference between the variable pressure chamber 23 and the constant pressure chamber 24 of the negative pressure booster 4 drops below a predetermined value, the electromagnetic switching valve 59 is switched to the atmosphere communication position I, and the variable pressure chamber 79 of the pilot valve 76 is changed. When the atmospheric pressure is introduced into the pressure chamber and the pressure difference between the constant pressure chamber 78 and the variable pressure chamber 79 does not occur, the negative pressure discharge valve 8
3 is opened and the negative pressure introduction valve 84 is closed, the pilot valve 76 is deactivated, and the atmospheric pressure is again introduced into the variable pressure chamber 56 of the vacuum drive pump 51. Therefore, the atmosphere is introduced into the variable pressure chamber 54 of the vacuum drive pump 51, the pressure difference between the constant pressure chamber 55 and the variable pressure chamber 56 is eliminated, and the power piston 54 is deactivated via the retainer 72 by the spring force of the return spring 73. Retreat to the position. As a result, the pump piston 61 also retracts, and the sump device 10
Is sucked into the annular chamber 71.

According to the ABS 2 of this example, the supply and discharge of the atmospheric pressure and the negative pressure to and from the vacuum drive pump 51 are performed via the pilot valve 76, and the electromagnetic switching valve 5
Since the switching is not performed via the switch 9, the capacity of the electromagnetic switching valve 59 can be reduced, and the electromagnetic switching valve 59 can be reduced in size.

[0078]

As apparent from the above description, according to the ABS of the present invention, since the vacuum drive pump is used, the conventional motor drive pump and its motor are not required, and the ABS control pump is not required. Can be reduced in weight, cost can be reduced, and noise can be further reduced.

Further, since the brake fluid discharged from the brake cylinder is returned to the MCY side, the amount of the brake fluid sent from the MCY to the brake cylinder can be reduced, and the low-pressure accumulator can be reduced.

In particular, according to the second aspect of the present invention, since the drive of the vacuum drive pump is controlled in accordance with the pressure difference of the negative pressure booster, when the brake fluid is returned to the MCY side, the vacuum operation pump is operated to the brake operating member. Kickback can be reduced, and the operation feeling can be improved.

According to the third aspect of the present invention, the number of components of the power piston can be reduced, the structure of the power piston can be simplified, and the assembling becomes easier.
Thus, the cost of the vacuum drive pump can be reduced.

According to the fourth aspect of the present invention, since the return spring for urging the pump piston to the non-operating position is not required, the total length of the vacuum drive pump can be shortened, and the spring case for supporting the return spring is provided. Can also be eliminated.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment of an anti-skid brake control system according to the present invention.

FIG. 2 is a longitudinal sectional view of the negative pressure booster shown in FIG.

FIG. 3 is a longitudinal sectional view of the vacuum drive pump shown in FIG.

FIG. 4 is a longitudinal sectional view partially showing another example of the vacuum drive pump.

FIG. 5 is a diagram schematically showing another example of the embodiment of the present invention.

6 is a longitudinal sectional view of the pilot valve shown in FIG.

FIG. 7 is a diagram schematically illustrating an example of a conventional brake system including an ABS.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Brake system, 2 ... Anti-skid brake control system (ABS), 4 ... Negative pressure booster, 5 ... Master cylinder (MCY), 7 ... ABS control holding valve, 8 ... Wheel cylinder (W / C), 9 ... A pressure reducing valve for ABS control
Reference numeral 10: sump device, 14: normally open first solenoid on-off valve, 15
... A normally closed second solenoid on-off valve, 22 ... Power piston, 23
... constant pressure chamber, 24 ... variable pressure chamber, 36 ... control valve, 41 ... output shaft, 45 ... negative pressure introduction pipe, 46 ... vacuum source, 50 ... inter-room connection passage, 51 ... vacuum drive pump, 52 ... first
Housing 53, second housing 54, power piston 54g central part 54h projection 54j cylindrical bulging part 55 constant pressure chamber 56 variable pressure chamber 59 electromagnetic switching valve 61 pump piston , 61a: concave portion, 69: suction side check valve, 70: discharge side check valve, 71
... annular chamber, 72 ... retainer, 72a ... teeth, 73 ... return spring, 76 ... pilot valve

Claims (4)

[Claims] 1. A brake operating member, comprising a constant pressure chamber into which a negative pressure is always introduced, and a variable pressure chamber into which a non-operating negative pressure is introduced and an atmosphere is introduced at the time of operation. A control valve is operated to introduce air into the variable pressure chamber, thereby boosting the operating force of the brake operating member and outputting the boosted force. A master cylinder that generates master cylinder pressure;
A brake cylinder that generates a braking force by the introduction of the master cylinder pressure, a low-pressure accumulator from which the brake fluid of the brake cylinder is discharged, and a normally open first that controls the introduction of the atmosphere to the negative pressure booster. An electromagnetic on-off valve, a normally closed second electromagnetic on-off valve for controlling direct communication and shutoff between the constant pressure chamber and the variable pressure chamber, and a passage connecting the master cylinder and the brake cylinder; A normally open third solenoid on-off valve for controlling communication and shutoff of a cylinder, and a passage for connecting the brake cylinder and the low-pressure accumulator are provided in a passage for connecting and disconnecting the brake cylinder and the low-pressure accumulator. A fourth solenoid valve which is closed and which operates according to a pressure difference between the variable pressure chamber and the constant pressure chamber of the negative pressure booster, and operates the block of the low pressure accumulator. At least a vacuum drive pump that sucks in the fluid and discharges the vacuum fluid from the third solenoid on-off valve to the master cylinder side, and further controls switching between introduction and discharge of negative pressure and atmospheric pressure to and from the vacuum drive pump. The vacuum drive pump discharges the brake fluid to the master cylinder side when a negative pressure is introduced by the electromagnetic switching valve, and discharges the negative pressure by the electromagnetic switching valve to reduce the atmospheric pressure. An anti-skid brake control system characterized in that when introduced, the low pressure accumulator is set to draw in brake fluid. 2. The anti-skid brake control system according to claim 1, wherein the switching of the electromagnetic switching valve is controlled according to a pressure difference between a variable pressure chamber and a constant pressure chamber of the negative pressure booster. 3. A vacuum drive pump comprising: a constant pressure chamber in which atmospheric pressure is constantly introduced; and a variable pressure in which atmospheric pressure is introduced from said electromagnetic switching valve when not operating and negative pressure is introduced from said electromagnetic switching valve when operating. A diaphragm made of rubber for partitioning the chamber, a diaphragm plate abutting on the surface of the diaphragm facing the transformer chamber, and one end of the diaphragm abutting on the diaphragm plate, interlocking with the operation of the diaphragm and the diaphragm plate. A pump piston for sucking and discharging the brake fluid by reciprocating; a center portion of the diaphragm is formed in a cylindrical block shape; and a constant pressure chamber of the vacuum drive pump is formed in the center portion of the cylindrical block shape. A projection that can be in contact with a housing that defines the diaphragm; A cylindrical bulging portion that bulges out on the side opposite to the diaphragm side is formed, and a cylindrical block-shaped central portion of the diaphragm fits into a concave portion formed on the diaphragm side of the diaphragm plate by the cylindrical bulging portion. Wherein the diaphragm and the diaphragm plate are constantly urged toward the constant pressure chamber of the vacuum drive pump by a return spring contracted into the variable pressure chamber of the vacuum drive pump. Item 3. An anti-skid brake control system according to item 1 or 2. 4. An annular retainer having a hole at the center is interposed between the return spring and the diaphragm plate, and teeth which are formed on the inner peripheral edge of the retainer are inclined toward the diaphragm plate. The pump piston and the retainer are integrally connected by passing one end of the pump piston through a hole of the retainer from the side opposite to the diaphragm plate toward the diaphragm plate. The anti-skid brake control system according to claim 3, wherein