JPS5889450A - Working fluid booster for brake gear for car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a housing having an inner bore, an inlet for coupling with a source of high pressure working fluid, and an outlet for coupling with a reservoir of working fluid; actuating a cylinder assembly; in operation, the boost piston is responsive to pressure conditions in the booster chamber by actuating fluid from the actuating fluid source; pressure conditions in the booster chamber are controlled by a valve arrangement operable to control fluid communication between the inlet section and the booster chamber and between the booster chamber and the outlet section; The apparatus relates to a fluid-operated booster for a vehicle braking system of the type operable in response to a load applied to a pedal-actuated human power member.

It is advantageous for the booster to be as short as possible in the axial direction in order to facilitate mounting on a vehicle. One method of obtaining a short length assembly is that the piston has a relatively small diameter central portion around which annular chambers are defined for coupling to the inlet and outlet portions. The inner bore and the booster piston have a stepped profile. Advantageously, the diameter is such that the high pressure fluid in the annular chamber connected to the inlet acts to bias the piston rearwardly. However, this means that
Boosters with inner holes at the rear and front ends of the annular chamber
This means that the sealing diameter between the pistons is larger than the sealing diameter between the inner bore in the center and the booster piston. This creates a problem in the assembly in that extra elements must be inserted into the bore to obtain a relatively small diameter for the central seal.

According to the invention, in the booster of the type described above, the j base,
The bore and the booster piston have a stepped profile, the diameter of the bore and the booster piston being such that the diameter of the sealing action of the booster piston at the rear end of the annular chamber is smaller than that at the front end of the annular chamber. At the front end of the annular chamber, a radial gap is formed between the booster piston and the bore, which is larger than the sealing diameter of the booster piston, and the inlet surrounds the booster piston. 5 configured and sealed to provide an annular chamber coupled to the booster piston, the front seal between the bore and the booster piston at the forward end of the annular chamber being radially deformable and connecting the bore and the booster piston. - It is attached to the wall surface of the inner hole so as to allow a radial gap between the pistons.

This has the advantage of simplifying the construction and assembly of the booster, since the booster piston can be incorporated into the bore without the need for extra components.

The front seal is of the type with a limited tolerance for radial clearance and radial elasticity, and the sealing diameter of the booster piston is such that the relatively large rear seal of the booster piston The booster piston can be installed from the front end of the bore by radially deforming the front seal to allow passage of the stop diameter and sufficiently seal the relatively small front diameter upon return. It is selected as follows.

Preferably, the front seal is in the form of a polytetrafluoroethylene (P, T, F, E, ) ring lined with an O-ring. This type of seal can withstand pressure differences of up to 200 bar, although it can tolerate radial gaps between the surfaces with a sealing effect of up to 0.4 mm.

The diameter of the inner bore and the booster piston can be configured such that a second annular chamber is formed around the booster piston, which is connected to the outlet. The front seal provides a seal between the first or high pressure annular chamber and the second or reservoir.

In one embodiment, the booster is configured such that the actuating fluid from the source causes an initial movement of the input member to cause at least a portion of the pneumatic movement in the brake device before the booster piston is advanced within the bore. It has an auxiliary piston that acts on the piston.

In another embodiment, the booster has an output power that is such that the reaction force sensed at the pedal is dependent on the load applied to the mask-〇 cylinder assembly and is independent of the magnitude of the boosting force acting on the booster piston. It is a response type. The load from the master cylinder assembly is
It is transmitted to the human power member operated by the pedal via the damping mechanism and valve device that constitute the block.

The valve device may be a spool valve acting within a bore in the booster piston.

The pedal-actuated input member is suitably an input piston which also acts in a bore within the booster piston.

Hereinafter, two embodiments of the present invention will be described with reference to the drawings.

The booster shown in Fig. 1 has an inner hole 2 that is stepped in the longitudinal direction.
and an inlet portion 3 for coupling the accumulator 63 to a source of suitably high pressure working fluid, and an outlet portion 4 for coupling to a reservoir 64 of working fluid.

A stepped booster piston 5 acts in said bore 2, which booster piston 5 is itself provided with a stepped bore 6 in the longitudinal direction. The input member 7 acts in the rearmost part 8 of the bore 6 and is retained by a ring 9. This input member 7 is actuated by an input rod 10 connected to a pedal (not shown), which rod 10 has a spherical head 11 held by the input member 7 . The valve arrangement 12 also acts in a relatively small diameter section 13 of the bore 6 of the booster piston to close the back of the booster piston 5 between a rear seal 15 in the housing and a rear seal 16 in the booster piston 5. The pressure state of the booster chamber 14 defined in the inner hole 2 is controlled.

The diameter of the booster piston 5 and the bore 2 is equal to that of the inlet portion 3.
An annular chamber 17, which is connected to the booster piston 5, is configured to surround the booster piston 5. This high-pressure chamber 17 is located between a rear seal 16 located on the booster piston 5 and a front seal 18 provided on the wall of the bore 2 at the point where the booster piston 5 is spaced from the bore 2. defined. A further annular chamber 19 surrounds the booster piston 5 in front of the high pressure chamber 17. This chamber 19 is connected to the outlet section 4 and is defined between the aforementioned front seal 18 and a further front seal 20 on the booster piston 5. The sealing diameter of the rear seal 16 is larger than that of the front (9) seal 18 so that the high pressure fluid in the high pressure chamber 17 acts to bias the booster piston 5 rearwardly. Seal 15.
16 and 18 are all polytetrafluoroethylene (P, T, F, E,
) The sealing ring 21 is made of These seals, which have a small hysteresis characteristic and are therefore particularly suitable for use in high pressure systems, also have a limited radial radius so that they can be subjected to a certain amount of radial strain without affecting their sealing properties. It has a certain amount of elasticity. However, these seals also have relatively large radial gap tolerances without being extruded under high pressure.

In this way, the front seal 18 can seal the high pressure chamber 17 with sufficient reliability without being pushed out.

An inclined passage 23 in the booster piston 5 extends from the annular reservoir 19 to the bore portion 13.

Similarly, the radial passage 24 connects the annular chamber 19 to the inner bore portion 13.
An inclined passageway 25 connects the booster chamber 14 to the bore portion 13 . Communication between these passages is controlled by a valve arrangement 12.

(lO) This valve device 12 comprises a cylindrical spool 26 which is biased rearwardly by a spring 27 acting in said bore portion 13 . The port 28 is connected by a radial passage 29 to a blind bore 30 in the spool 26 which opens into a chamber 31 defined in the bore portion 13 forwardly of said spool 26 .

The passageway 23 opens into the chamber 31 in the illustrated retracted position so that the booth chamber 14 communicates with the reservoir chamber 19.

This chamber 31 forms an auxiliary pressure chamber, the pressure inside of which acts on an auxiliary piston/32 acting in the large diameter section 33 of the bore section 13. The amount of movement of this auxiliary piston 32 is limited by an end member 34 located in the bore portion 13. A spring 35 acts between the end member 34 and the auxiliary piston 32 to bias the auxiliary piston 32 rearwardly. Auxiliary piston 32 acts on an output rod 36 for actuating a master cylinder assembly (not shown).

The auxiliary piston 32 and the spool 26 are each The inside of the bore 6 is sealed by loops 37 and 38.

The structure of the booster is relatively simple and compact,
Therefore, it can be seen that assembly of the booster becomes easy. Once these parts are assembled inside the booster piston 5 and the rear seals 15 and 18 are in place, the booster piston 5 is inserted through the front end of the bore 2 and the front seal 18 is elastically It deforms to pass through the relatively large sealing diameter of the rear seal 16 and then returns to its sealing condition against the booster piston 5. As mentioned above, the front seal 18 has a loaded P as its sealing surface,
Since the ring is made of T, F, E, there is no extrusion and a relatively large diametrical gap is created between the booster piston 5 and the bore 2, in this example 0.5 mm. Such a seal can indeed tolerate a diametric gap of 0.8 mm, but the high pressure chamber 17
is selected such that the reservoir chamber 19 can deliver working fluid to the passageway 24 from a high pressure working fluid source.
connects the outlet part 4 to the inclined passage 23 during all (12) stages of movement of the piston.

The operation of this booster is as follows.

In the illustrated retracted position, chamber 31 and booster chamber 14 are in communication with reservoir chamber 19 .

The pressure within the high pressure chamber 17 acts to bias the booth piston 5 rearward. When the pedal is operated, a load is applied to the input member 7 by the input rod IO. This input member 7 moves forward and advances the spool 26 against the force of the spring 270. Movement of the spool 26 is isolated from the inclined passage 23 from the chamber 31 and thus from the booster chamber 14. Further movement of the spool 26 is
Port 28 is opened to establish communication between passages 24 and 25 through which high pressure working fluid flows into booster chamber 14 . At the same time, this high-pressure working fluid is introduced into chamber 31 via passage 29 and blind hole 30 and acts on auxiliary piston 32 .

The area of action of the booster piston 5 and the auxiliary piston 320 is such that in this action stage, the acting force acting on the booster piston 5 in the forward direction is greater than the acting force acting on the booster piston 5 in the backward direction. is constructed such that it is also smaller or equal to this. In this example, this means that the booster chamber 14 is % larger than or equal to the active area of the auxiliary piston 320 (ignoring spring and frictional forces). Therefore, the increased pressure in the chamber 31 acts on the auxiliary piston 32 and the output rod 36.
is advanced against the booster piston 5, and the master
Operate the cylinder to absorb the air gap inside the braking device.

The auxiliary piston 32 engages the end member 34, thus preventing further movement of the auxiliary piston 32 relative to the booth piston 5.

When the auxiliary piston 32 engages the end member 34, the force acting on the auxiliary piston 32 due to the increased pressure in the chamber 31 is transmitted to the booster piston 5 and acts directly on the booster piston 5. The rearward acting force due to the increased pressure in chamber 31 is counteracted. Therefore, the rearward acting force on the booster screw (I4) ton 5 is reduced, and the booster piston 5 moves forward inside the bore 2 to increase the power output.

This increased pressure also acts rearwardly on the spool 26, and this reaction force is transmitted to the input member 7, creating a "feel" in the pedal. When this reaction force on the spool 26 is equal to the load applied from the pedal, the booster piston 5 moves forward relative to the spool 26.
, cutting off communication between the passage 24 and the boat 28. The booster is now in its equilibrium or inactive state.

If the load on the pedal is reduced but not completely removed, the spool 26 can be moved rearwardly relative to the booster piston 5 to open the inclined passage 23, increasing the pressure until an equilibrium position is again reached. to allow the booster piston to move.

When the load on the pedal is removed, the spool 26 moves rearwardly to open the inclined passage 23 and connect (15) to the hydraulic fluid reservoir, such as the chamber 31 and the booster chamber 14. The spool 26 and booster piston 5 move rearward and the spring 35 moves back when the build-up pressure decreases to a lower level.
shifts the auxiliary piston 32 to its retracted position.

The booster shown in FIG. 2 is basically similar in construction to that shown in FIG. 1, and corresponding reference numbers have been applied to corresponding parts.

The difference lies in the structure of the valve device 12 and the auxiliary piston 32.
An alternative to this is the use of a relaxation mechanism 39 that makes the booster an output response type instead of an input response type.

The overall structure of booster piston 5 is thus similar to that of FIG. It acts inside the hole 6. 6-L, the valve device 12 is a two-part east spool 40, the spring 41 acting between the enlarged shoulder 42 at the rear end of the spool 4o and the step 43 of the bore 6. A first spool portion 44 at the forward end that biases the spool rearward has a port 45 permanently coupled (16) to the inclined passageway 23 extending to the reservoir 19. This port 45 is connected by a passageway 46 to a blind bore 47 opening into an axial bore 48 in the second spool section 49 . At its rear end, the spool portion 49 is connected to the inner hole 4.
8 into the chamber 51 in the part of the inner hole 6 where the input member 7 acts.
A diametrical passageway 50 is provided that connects with. Room 5
The pressure in 1 acts rearwardly on the input member 7, but the chamber 51 is formed into a reservoir by passage 50, bore 48, 47, port 45 and inclined passage 23 so that this pressure remains constant. 17 is always connected.

The spool portion 49 controls the communication state between the passages 24 and 25, thereby controlling the communication state between the high pressure chamber 17 and the booster chamber 14. A port 53 in spool portion 49 is connected to axial bore 48 by a diametric passageway 54 . This port 53 controls communication between the reservoir chamber 19 and a passage 55 in the booster piston 5 leading to the booster chamber 14 .

Instead of the auxiliary piston 320, a relief mechanism 39 consisting of a rubber block (17) 56 is arranged at the forward end of the bore 6 between the booster piston 5 and the output rod 36.

This block 56 transfers a portion of the load applied to the master cylinder via the valve device 12 back to the input member 7 to produce a feeling of action on the pedal. Therefore, the present booster is output responsive rather than input responsive as in FIG. 1, where the action of the augmented pressure produces a sensation in the pedal.

The booster assembly shown in Figure 2 shows the assembled booster
Similar to the assembly of FIG. 1, in which the piston 5 is inserted into the housing 1 from the front end of the bore 2.

Therefore, the sealing diameter of the rear seal 16 is elastically deformed in the radial direction through the front seal 18, and the rear-front seal 18 resumes its sealing effect on the booster piston 5.

In the illustrated inactive position, all parts are in the retracted position and the booster chamber 14 is connected to the reservoir chamber 19. When a load is applied to the pedal, the input member 7 advances and moves the spool (!8) 40 into contact with the block 56 against the force of the spring 410. First, boat 53 has booster room 1
4 and reservoir chamber 19 , and then annular port 52 opens to establish communication between passages 24 and 25 to introduce high pressure working fluid to booster chamber 14 . Booster piston 5 advances within bore 2 and applies a force to the master cylinder, which force is transmitted via block 56 and output rod 36.

The reaction of the load applied to the master cylinder acts in a rearward direction, passing through the output rod 36 to the block 56.
and deforms the block 56. The load applied to the master cylinder is reduced by block 56 and this reduced load is returned to the pedal via spool 40 and input member 7 to create a reaction window in the pedal.

When the reaction force applied to the spool 40 exceeds the load applied by the pedal, the spool (19) 40 moves relatively rearward until the communication between the passages 24 and 25 is interrupted. The booster is now in its equilibrium position.

If the input load is reduced, block 56 pushes spool 40 a further distance rearwardly to reestablish communication between booster chamber 14 and reservoir chamber 19 until the equilibrium position is again reached. .

When the input load is completely removed, spool 40 moves back to balance connecting booster chamber 14 to reservoir chamber 19 and the parts return to their illustrated retracted positions.

Thus, the present invention provides a booster that is simple in structure and easy to assemble, thereby reducing the cost of the booster.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a fluid action booster;
The figure shows a longitudinal sectional view of another fluid action booster. (20) 10...Input lot, 11...Head, 1
2... Valve device, 13... Inner hole portion, 14.
・・Booster room, 15.16・・Rear seal, 1
7... High pressure chamber, 18.20... Front seal, 1
9...Storage chamber, 21...Sealing ring, 22...
・0 ring, 23... inclined passage, 24...
passage, 25... inclined passage, 26... spool,
27...Spring, 28...Boat. 29... passage, 30... blind hole, 31... room,
32... Auxiliary piston, 33... Large diameter portion, 34... End member, 35... Spring, 3
6...Output lot, 37...Seal, 38...
・Seal, 39... Relaxation mechanism, 40... Spool % 41... Spring, 42... Shoulder, 43.
...Stepped part, 44...Spool part, 45.° Port 46...Passway, 47...Blind hole, 48...Inner hole, 4
9... Spool part, 50... Passage, 51... Chamber, 52.53... Port, 54... Passage, 55...
- Passage, 56...Block, 63...Accumulator, 64...Working fluid reservoir. (21) Patent applicant Lucas Industries Public Limited Company (22)

Claims (1)

[Claims] 1. Nozzing provided with an inner hole having a step-shaped profile, an inlet portion for connecting to a supply source of high-pressure working fluid, and an outlet portion for connecting to a reservoir of working fluid. a pedal-operated input member; and a booster having a stepped profile for actuating a master cylinder assembly acting within said bore.
a piston, the booster piston being advanced in the bore in response to an increase in pressure in the booster chamber by actuating fluid from the source and in response to a load applied to the input member. A 7°-vehicle brake system comprising a valve device for controlling the pressure state of the booster chamber, the valve device being operable to control the communication state between the inlet section and the booster chamber and between the booster chamber and the outlet section. In a working fluid booster for the device, the bore and the diameter of the booster piston are configured and sealed to provide an annular chamber surrounding the booster piston and connected with the inlet, and the diameter of the booster piston is configured and sealed to The sealing diameter of the booster piston at the rear end of the annular chamber is larger than the sealing diameter of the booster piston at the front end of the annular chamber, and there is a gap between the booster piston and the bore at the front end of the annular chamber. A radial gap is provided, and a front seal between the bore and the booster piston at the front end of the annular chamber is provided with a front seal that is radially deformable and a radial gap between the bore and the booster piston. A working fluid booth characterized in that it is provided on the wall surface of an inner hole so as to be able to absorb voids in the direction. 2. The front seal has a limited allowance for radial clearance and radial elasticity, and the booster
The sealing diameter of the piston is such that the booster piston is installed from the front end of the bore by radially deforming the front seal to allow passage of the relatively large rear sealing diameter of the booster piston. 2. A booster as claimed in claim 1, wherein the booster is selected such that it can return to a state of sealing a relatively small front diameter. 3. The booster according to claim 1 or 2, wherein the front seal is a polytetrafluoroethylene ring backed by an O-ring. 4. The inner bore and the booster piston are connected to the outlet and a second annular chamber is formed around the booster piston to form a high pressure annular chamber and a second annular chamber with the front seal. A booster according to any of the preceding claims, characterized in that the booster is configured to provide a sealed state between the VC and the VC.