JPH0356220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention regulates the supply of hydraulic fluid from a source to a motor vehicle brake by means of a regulator assembly in accordance with a skid signal from a skid sensing means, and at least one regulator assembly operating within a bore. The present invention relates to a hydraulic anti-skid brake system for a motor vehicle of the type having an actuating chamber in which a hydraulic pump containing a plunger communicates with a regulator assembly to control re-braking after skid correction.

British Patent A No. 2029914 (Japanese Unexamined Patent Publication No. 55-36187 or Japanese Patent Publication No. 1-27901) and A No. 2069640
In the case of the anti-skid brake device described in Japanese Patent Application Laid-open No. 56-128256 or Japanese Patent Publication No. 1-21024, the adjustment device assembly has a bore, and the deboost piston operates within the bore. and cooperate with the control valve assembly. The control valve assembly is adapted to control communication between the supply fluid and the brake through an expansion chamber formed between the piston and the control valve assembly. The piston is normally held in an inoperative, forward position by the entrained volume of fluid supplied by the pump, in which the valve assembly is fully open and
The effective volume of the expansion chamber is minimal. When the squid signal occurs, the fluid entrapment is released, which causes the piston to move to the retracted position, initially closing the valve assembly, isolating the supply from the brake, and then opening the expansion chamber to the active position. The volume can be further increased, thereby allowing brake application pressure to escape. After correction of the skid, pressure from the pump acts to drive the piston toward its forward position, first by pressurizing the fluid in the expansion chamber to reapply the brakes, and later by opening the valve assembly. , reestablishing communication between the supply fluid and the brake.

In the regulator assembly of GB A 2029914 and GB A 2069640, the volume of trapped fluid supplied by the pump to the deboost piston also acts on the plunger part of the pump, causing the plunger to cooperate with the drive mechanism. The actuating piston, which maintains the pump in a disabled, inoperative condition and is responsive to pressure from the source, is actuated such that the plunger engages the catch by direct cooperation with the proximal end of the piston. .
A space is defined by the proximal portion of the bore between the plunger and the proximal end of the piston for accommodating a volume of confined fluid at the same pressure as the pressure acting on the deboost piston. After correction of the skid, at the end of the unlock cycle, the volume of trapped fluid in the space acts to maintain the plunger in an advanced position in cooperation with the drive mechanism. This is usually not enough to start the pump, but it does create unwanted vibrations and noise. This tendency becomes more pronounced when the confined fluid expands, for example due to a significant increase in local temperature.

According to the invention, in a hydraulic brake system of the type described above, the regulator assembly comprises a bore in which a deboost piston operates and cooperates with a regulating valve assembly; Communication between the hydraulic fluid and the brake is adjustable.
A confined fluid volume that holds the deboost piston in an inactive, forward position is supplied to the deboost piston by a pump, which engages a plunger operating within the pump bore and drives the plunger in one opposite direction. responsive to the drive mechanism and to pressure from the source and in direct cooperation with the plunger;
an actuating piston that drives the plunger toward the drive mechanism, a volume of fluid trapped above a portion of the plunger acts to hold the plunger in an inoperative position out of cooperation with the drive mechanism, and the actuating piston stops A space is formed between the piston and the proximal end of the plunger by a proximal portion of the bore in which the plunger and actuating piston actuate, having a portion held in the retracted position against the metal, and in which the plunger and the actuating piston actuate. When the actuating pistons move apart from each other, a pressure reducing valve is actuated to allow the pressure in the space to be released.

Typically, the pressure reducing valve is actuated to relieve the pressure in the space only after the plunger and piston have moved apart from each other a predetermined distance that is less than the distance required to cause the plunger to cooperate with the drive mechanism. Therefore, it is possible to prevent the plunger from accidentally collaborating with the drive mechanism.

Preferably, the pressure reducing valve operates when the plunger and the actuating piston move a predetermined distance relative to each other to cause the fluid in the space to return to the reservoir.

The pressure reducing valve includes a valve member capable of being held in engagement with a valve seat of the plunger by a spring and isolating the space from the reservoir, an actuating piston cooperating with the plunger during operation of the pump, and further comprising a valve member that isolates the space from the reservoir; Advantageously, the valve member is withdrawn from the valve seat when the proximal end of the actuating piston is separated by the predetermined distance.

The valve member may include a headed stem connected to the actuating piston by a lost motion joint, or it may include a ball mounted in a retainer by the actuating piston. The ball is prevented from moving too much with the plunger by the retainer when the plunger leaves the working piston.

The pressure reducing valve comprises a one-way valve through which fluid is drawn into the pumping space defined by said space during the suction stroke of the plunger. Then, during the output stroke of the plunger, fluid flows from this space through the second one-way valve.
evacuated and provides a confined fluid volume.

Two embodiments of the invention are illustrated in the accompanying drawings.

The assembly shown in the accompanying drawings comprises a housing 1 with a regulator assembly 2, a hydraulic pump assembly 3 and a foot valve 4. Housing 1
A shaft 5 extending longitudinally from both ends through the housing 1 is connected at one end to the wheel to be controlled and at the other end skid sensing means (Fig. (not shown) is provided.

The foot valve 4 and the skid sensing means may be of any type disclosed in GB A 2029914, and the pump assembly 3 is of the type disclosed in GB A 2029914.
This is the same as disclosed in No. 2069640. The pump 3 is driven in one direction by an eccentric 5a on the shaft 5 and in the opposite direction by pressure from a foot-operated master cylinder 15 acting on the working piston 3a. The pump 3 will be explained in more detail later.

Regulator assembly 2 extends from foot valve 4 and includes a bore 8 within which a deboost piston 9 operates. The piston 9 is normally driven into the inoperative position by a catch, which is pressed against the wall 1 by a spring 12 at the closed end of the generally cup-shaped sleeve 11.
0, the sleeve 11 is connected to the bore 8 by means of a seal 13 for the end of the bore 8 remote from the foot valve 4.
held within.

The control valve assembly 14 housed within the sleeve 11 has a bore 8 between the piston 9 and the control valve assembly 14 itself.
The communication between the foot-operated master cylinder 15 and the wheel brakes 16 is regulated via an expansion chamber formed therein.

The control valve assembly 14 includes a continuously operated first valve 1
8 and a second valve.

The first valve 18 has an intermediate diameter portion which operates within the bore of the sleeve 11 and a maximum diameter outer portion which operates within the closure body 13.
A first of the stepped piston type, which operates in a blind bore 21 of the piston, whose inner part of smaller diameter carries an annular seal 22 forming the valve head, and whose innermost part of smallest diameter extends into a circular hole 23 in the wall 10; A valve member 20 is provided. The valve head 22 is engageable with a valve seat 29 having a ring in the wall surrounding the circular hole 23. Normally, the valve head 22 is spaced apart from the valve seat 24 by a spring 25 acting between the wall 10 and the shoulder 26 at the step between the medium diameter and small diameter portions of the piston 20.

The piston 20 has a stepped, longitudinally extending, open end bore 27 having a second valve 19 housed therein. The second valve 19 includes a ball-shaped valve member 28 engageable with a valve seat 29 formed by a shoulder in the diameter of the bore 27 . The ball 2
8 is normally urged away from the valve seat 29 by a search needle 30. The piston 9 cooperates with the groping needle 30 against the force of a light compression spring 31.

In the normal inoperative position shown, the foot valve 4 is closed, so that the piston 9 is held in the forward inoperative position, in which the second piston 19 is inserted into the searching needle 3.
0, the first valve remains open by spring 2.
5, it remains open.

When the master cylinder 15 is actuated to apply the brake, hydraulic fluid is supplied to the brake through the radial hole 33 in the wall of the sleeve 11 and also to the expansion chamber 17 through the first valve 18. . At the same time, fluid also enters the through-bore 27 through the hole 32 in the wall of the piston 20 and into the open second
Through valve 19 it can flow into the expansion chamber.
In this manner, fluid flows to the brake substantially unimpeded.

Fluid from the master cylinder acts on the valve head 22 and the stepped diameter shoulder 26 on the outer end of the wide area piston 20. Master cylinder 15
The pressure acting on the end of the widest area causes the force acting on the piston 20 to be equal to the force of the spring 25 and the pressure acting on the shoulder 26 and the valve head 22. Unrestricted communication will continue until victory is achieved. The first valve 18 is then closed, after which only a small pressure increase occurs due to the fluid passing through the unrestrained passage with the air gap between the valve seats 29.

When the skid signal is received, foot valve 4 opens to release the trapped fluid volume in bore 8.
Piston 9 can be moved back against the force of spring 12. Since the pressure at which the skid signal is generated is higher than the pressure at which the first valve 18 is closed, first,
The second valve 19 can be closed. As a result, communication between the master cylinder 15 and the brake 16 is cut off, the piston 9 continues to retreat, and the effective volume of the expansion chamber 17 continues to increase, thus releasing the pressure acting on the brake 16. I can do it. When the foot valve 4 is opened, the pump 3 becomes unbalanced and fluid is pumped through the foot valve 4 from the returning reservoir 32 into the bore 8 in a closed circuit. Since communication between the piston 3a and the master cylinder 15 is not restricted, the pump 3 can operate freely.

When the skid signal ends, foot valve 4 closes, isolating bore 8 from reservoir 32, and then
Pump 3 operates to increase the pressure within bore 8,
As a result, the piston 9 is driven to its inoperative retracted position. An initial movement of the piston 9 in this direction pressurizes the trapped fluid volume in the expansion chamber 17 and reapplies the brake 16, and a subsequent movement causes the second valve 19 to open. , fluid can flow unrestricted from the master cylinder to the expansion chamber 17 through the gap between the ball 28 and the valve seat 29. In this way, the first valve 18 closes at a predetermined pressure, regardless of the movement of the piston 9.

The second valve 19 closes when the piston 9 leaves the stopper 10 of the sleeve 11, and opens when the piston 9 moves toward the stopper 10. When the pressure from the master cylinder 15 drops below the predetermined pressure, the first valve 18 reopens and the fluid flows between the master cylinder 15 and the brake 1.
6 can flow freely and unrestricted.

The pump 3 is equipped with a plunger in the form of a differential piston 40 operating in a stepped bore 41. Seals 42 and 43 are attached to each of the two parts of the piston 40, respectively.

The working piston 3a cooperates with the proximal end of the piston 40, and the bore 44 in which the piston 3a works is connected to the stepped bore 41.

A first one-way valve 45 is housed within the piston 40 and as the piston 40 moves away from the open end closure 47 of the bore 41, fluid passes through the one-way valve and into the bores 41, 44. into the pumping space 46 formed therein. The valve is provided with a bore 44 in which the actuating piston 3a operates. As the piston 40 moves in the opposite direction, fluid engages the seal 42 and the bore 41 and flows into the pumping chamber through the axial wall of the groove housing the second one-way valve and seal formed in a known manner. 46 into the bore 8.

The one-way valve 45 has a stem 55 fitted with an enlarged head 56 which engages a valve seat 57 at the inner end of a bore 58 in the piston 40 that reaches the reservoir 32.
A spring 59 acting between the head 56 and the proximal end of the piston 3a urges the head 56 toward the valve seat 57. The stem 55 extends axially into a complementary fluid bore 60 at the proximal end of the actuating piston 3a;
It carries a horizontal pin 61. The pin 61 is fitted into a transverse bore 62 of a considerably larger diameter than the pin;
A lost motion joint is formed with the piston 3a.

To explain the operation, the piston 40 is connected to the piston 40 through the tappet 50 during the suction stroke.
The tappet 50 is biased by the spring 51 in a direction away from the eccentric 5a.

In the non-operating position where the pump 3 is inactive at bottom dead center, the operating piston 3a is located at the outer end surface 5 of the bore 44.
2 and the piston 40 is held in the retracted position against a stop formed by Well, piston 3
Retreat toward the inner edge of a. In this position, the one-way valve 45 is normally closed, so fluid is trapped within the pumping space 46.

The relative spacing between the piston 40 and the piston 3a depends on the amount of fluid trapped in the pumping space 46 at the same pressure as the pressure acting on the bore 8. At the end of the unlock cycle, tappet 50 and piston 4
0 position is not at bottom dead center and the piston 40 is separated from the piston 3a by a sufficient distance to absorb the lost motion of the joint, the valve seat 57
moves away from the valve head 56. Movement of the valve head 56 together with the piston 40 is prevented by the co-operation of the pin 61 with the wall of the bore 62. This releases the pressure in the pumping space 46 by opening the return passage to the reservoir 32 and further movement of the piston 40 in the same direction is prevented.

The one-way valve opens to ensure that the pressure in the pumping space 46 can be released before the piston 40 separates from the piston 3a by a distance sufficient for the tappet 50 to engage the eccentric 5a. , the degree of lost motion is determined.

In the modified structure shown in FIG.
5 has a ball 65, and the ball 65 is connected to the ball 6.
The valve seat 5 is biased by a spring 69 acting between the inner end of the groove of the piston 3a containing the spring and the valve seat 5.
7. The inner end of the actuating piston 3a is sealed in a retainer 66 in the form of a collar with a shrunken skirt around the piston 3a, and a ball 65 passes through the end wall and engages the valve seat 57. A central opening 67 is provided.

The piston 40 is the actuating piston 3 as described above.
When separated from a, the movement of the ball 65 with the piston 40 is restrained by the action of the spring 68, as the flange surrounding the opening 67 engages the ball 65. When piston 40 subsequently moves in the same direction relative to piston 3a, one-way valve 45 opens, releasing pumping space 46 to reservoir 32 as described above.

The structure of the one-way valve in FIG. 2 other than the above is the same as that in FIG. 1, and corresponding parts are designated by corresponding symbols.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the regulator and skid sensing assembly of a hydraulic anti-skid brake system suitable for use in motorcycles, light passenger cars or light trucks, and FIG. 2 is an enlarged cross-section of a portion of the pump according to a variant. It is a diagram. Explanation of main symbols, 1...Housing, 2...Adjusting device assembly, 3...Hydraulic pump assembly, 4...Foot valve, 5...Shaft, 6...Cylindrical guard, 8...Bore, 9...
Deboost piston, 10... Closing end wall, 11... Sleeve, 13... Sealing body, 14... Control valve assembly, 1
5... Foot-operated master cylinder, 16... Wheel brake, 18... First valve, 19... Second valve, 22... Annular seal, valve head.

Claims (1)

Claims: 1. The supply of working fluid from the supply source 15 to the vehicle brake 16 is regulated by the regulator assembly 2 in accordance with the skid signal from the skid sensing means, and the bore of the hydraulic pump 3 is adjusted to the skid position. a control valve assembly comprising an actuating chamber 46 in communication with the regulator assembly for controlling re-application of the brake after correction, the regulator assembly controlling communication between the source and the brake; a deboost piston 9 cooperating with 14 has a bore in which it slides, and fluid is supplied by the pump to the deboost pump, which is confined to hold the deboost piston in an inoperative forward position; The pump includes a plunger 40 that slides within a pump bore 41, a drive mechanism 5a that drives the plunger in one of two mutually opposite directions, and a drive mechanism 5a that is responsive to pressure from the source and that drives the plunger. an actuating piston 3a for driving the plunger towards the drive mechanism in direct cooperation with the actuating piston 3a, the trapped fluid acting on a portion 53 of the cross-sectional area of the plunger to drive the plunger towards the drive mechanism. holding said plunger in an uncooperative inactive position and in a retracted position in which said actuating piston rests against a stop 52, by means of adjacent portions of the two bores in which said plunger and actuating piston respectively slide; In the automobile hydraulic anti-static brake system in which a space 46 is defined between the adjacent ends of the actuating piston and the plunger, when the plunger and the actuating piston move away from each other, the pressure reducing valve 45 is actuated. The pressure reducing valve 45 is held in engagement with a valve seat 57 in the plunger 40 by a spring 59 to release the pressure in the space 46 from the reservoir 32. during operation of the pump, the actuating piston 3a is isolated from the plunger 40.
the valve member is retracted from the valve seat as soon as the respective adjacent ends of the plunger and the actuating piston are separated from each other by a predetermined distance. skid brake device. 2. Only after the plunger and piston 3a have moved away from each other by a predetermined distance shorter than the distance required for the plunger 40 to cooperate with the drive mechanism 5a, the pressure reducing valve 45 is closed.
2. The hydraulic anti-skid brake device according to claim 1, characterized in that the pressure in the space 46 can be released. 3 The valve member 65 is connected via the idle joint 61,
a stem with a head 5 connected to the actuating piston;
Claim 1 characterized in that it comprises:
Hydraulic anti-skid brake device described in item 1 or 2. 4 said valve member 5 consists of a ball carried by said actuating piston 3a in a retainer 66;
Claims 1 to 3, characterized in that when the plunger is separated from the working piston, the retainer 66 prevents excessive movement of the ball relative to the working piston. Hydraulic anti-skid brake device described in any one of the preceding paragraphs. 5. The pressure reducing valve 45 is a one-way valve, and during the suction stroke of the plunger, fluid is introduced into the pressure feeding space constituted by the space 46 through the one-way valve, and during the output stroke of the plunger, the fluid is introduced into the pressure-feeding space formed by the space 46. Claims 1 to 4, characterized in that the fluid is discharged through two one-way valves 42 to provide the trapped fluid.
Hydraulic anti-skid brake device described in any one of the preceding paragraphs.