JPH0313106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a housing having an inner bore, an inlet portion for coupling with a source of high pressure working fluid, and an outlet portion for coupling with a reservoir of working fluid; a booster piston operative in the bore to actuate the master cylinder assembly, and in operation, the booster piston operates in the bore in response to an increase in pressure in the booster chamber by working fluid from the working fluid supply. the pressure conditions in the booster chamber are controlled by a valve arrangement operable to control fluid communication between the inlet and the booster chamber and between the booster chamber and the outlet;
This valve system relates to a fluid-operated booster for a vehicle brake system of the type operable in response to a load applied to a pedal-actuated input member.

In order to facilitate mounting on a vehicle, it is advantageous for the booster to be as short as possible in the axial direction. One way to obtain short length assemblies is to
the piston has a relatively small diameter central portion;
The booster piston and bore have a stepped profile around which annular chambers are defined for connection to the inlet and outlet sections. 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 the sealing diameter between the inner hole and the booster piston at the rear and front ends of the annular chamber is larger than the sealing diameter between the inner hole and the booster piston at the center. means. For this reason,
A problem arises in the assembly in that extra elements must be inserted into the bore to obtain a relatively small diameter for the central seal.

Boosters of the above-mentioned type have an internal bore and a booster piston with stepped contours, the diameter of which is such that the diameter of the internal bore and the booster piston is such that the sealing action of the booster piston at the rear end of the annular chamber a diameter larger than a sealing diameter of the booster piston at the front end of the annular chamber;
The annular chamber is configured and sealed to surround the booster piston and provide an annular chamber coupled with the inlet so as to create a radial gap between the booster piston and the bore at the forward end of the annular chamber. , the front seal between the bore and the booster piston at the front end of the annular chamber is radially deformable and capable of allowing a radial gap between the bore and the booster piston. Some are attached to the wall of the hole.

An object of the present invention is to provide a booster of this type with a simple structure in which a booster piston can be easily installed.

The present invention provides a booster of the type described above in which the front seal is radially deformed to permit passage of a relatively large rear seal working diameter of the booster piston, and The two sealing diameters of the booster piston are selected such that the booster piston can be inserted from the front end of the inner hole by returning to the sealing state. be.

Since the booster of the present invention can be assembled by simply inserting the booster piston from the front end of the inner hole of the housing, the structure is simple, easy to assemble, and manufacturing and assembly costs are reduced.

Preferably, the front seal is in the form of a polytetrafluoroethylene (PTFE) ring lined with an O-ring. This type of seal can tolerate a radial gap between the surfaces in which it has a sealing effect of up to 0.4 mm, but can withstand pressure differences of up to 200 bar.

The diameter of the inner bore and the booster piston may 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 provides an output response in which the reaction sensed at the pedal is dependent on the load applied to the master cylinder assembly and is independent of the magnitude of the boosting force acting on the booster piston. It is of type. Loads from the master cylinder assembly are transmitted to the pedal-operated input member through a damping mechanism and valving mechanism comprising a rubber 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 of FIG. 1 has a longitudinally step-shaped internal bore 2 and an inlet 3 for connecting an accumulator 63 to a source of suitably high-pressure working fluid.
and an outlet portion 4 for connection 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 coupled to a pedal (not shown), which rod 10 is connected to a spherical head 1 held by the input member 7.
1. The valve arrangement 12 also acts on a relatively small diameter section 13 of the bore 6 of the booster piston to close a rear seal 15 in the housing.
and rear seal 16 in booster piston 5
The pressure state of the booster chamber 14 defined in the inner bore 2 at the back of the booster piston 5 is controlled between the booster piston 5 and the booster chamber 14 .

The diameters of the booster piston 5 and the inner bore 2 are:
An annular chamber 17 connected to the inlet portion 3 is configured to surround the booster piston 5 . This high-pressure chamber 17 is defined between a rear seal 16 on the booster piston 5 and a front seal 18 on the wall of the bore 2 at the point where the booster piston 5 is spaced from the bore 2. be done. 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 working diameter of the rear seal 16 is larger than the working diameter of the front seal 18 so that the high pressure fluid in the high pressure chamber 17 acts to bias the booster piston 5 rearwardly. Seals 15, 16 and 18 are all made of polytetrafluoroethylene (P.
The sealing ring 21 is made of TFE. These seals, which have a small hysteresis characteristic and are therefore particularly suitable for use in high pressure systems, also have a limited directional 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, a radial passage 24 connects the annular chamber 19 to the bore portion 13 and an inclined passage 25 connects the booster chamber 14 to the bore portion 13. Communication between these passages is controlled by a valve arrangement 12.

The valve device 12 includes a cylindrical spool 26 acting in the bore portion 13 and biased rearwardly by a spring 27. 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 connects the chamber 31 in the illustrated retracted position such that the booster chamber 14 communicates with the reservoir chamber 19.
It is open inward.

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 part 13. The amount of movement of this auxiliary piston 32 is limited by an end member 34 located in the bore portion 13. 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 sealed inside the bore 6 by seals 37 and 38, respectively.

It can be seen that the structure of the booster is relatively simple and compact, which facilitates assembly of the booster. Once these parts are assembled inside the booster piston 5, the rear seals 15 and 18
is in place, the booster piston 5
is inserted from the front end of the bore 2, and the front seal 18
deforms elastically to pass through the relatively large sealing diameter of the rear seal 16 and then returns to the sealing condition against the booster piston 5. As mentioned above, the front seal 18 has a loaded PTFE ring as its sealing surface, so that it does not get pushed out and creates a relatively large diametrical gap between the booster piston 5 and the bore 2. void, in this example
There is a margin of 0.5mm. Although such a seal can in practice permit a diametric gap of 0.8 mm, the diameter is selected such that the high pressure chamber 17 can deliver working fluid to the passageway 24 from a high pressure working fluid source. The reservoir 19 connects the outlet 4 to the inclined passage 23 during all stages of piston travel.

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 in the high pressure chamber 17 is the booster piston 5
acts to bias backward. When the pedal is operated, a load is applied to the input member 7 by the input rod 10. This input member 7 moves forward and advances the spool 26 against the force of the spring 27. Movement of spool 26 blocks inclined passage 23 from chamber 31 and thus booster chamber 14
cut off from Further movement of spool 26 opens communication between passageways 24 and 25 through port 28, allowing high pressure working fluid to flow 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 32 is such that in this stage of action, the acting force acting on the booster piston 5 in the forward direction is smaller than the acting force acting on the booster piston 5 in the rearward direction. or are configured to be equal to this. In the present example, this means that the booster chamber 14 is larger than or equal to the active area of the auxiliary piston 32 (ignoring spring and frictional forces). The increased pressure in the chamber 31 therefore acts on the auxiliary piston 32 to advance it and the output rod 36 relative to the booster piston 5, actuating the master cylinder and absorbing the void within the brake system. The auxiliary piston 32 engages the end member 34 and thus the booster piston 5
Further movement of the auxiliary piston 32 relative to the piston 32 is prevented.

When the auxiliary piston 32 engages the end member 34,
Auxiliary piston 32 for increased pressure in chamber 31
The force acting on the booster piston 5 is transmitted against the booster piston 5 to counteract the rearwardly acting force due to the increased pressure in the chamber 31 acting directly on the booster piston 5. Therefore, the rearward acting force on the booster piston 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 spool 26 is equal to the load applied from the pedal, booster piston 5 moves forward relative to spool 26, interrupting communication between passage 24 and port 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, spool 26 moves rearwardly to open inclined passage 23 and connect chamber 31 and booster chamber 14 to the hydraulic fluid reservoir. Spool 26 and booster piston 5 move rearwardly and spring 35 shifts auxiliary piston 32 to its retracted position when the build-up pressure decreases to a lower level.

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 arrangement 12 and the use of a relaxation mechanism 39 in place of the auxiliary piston 32 which makes the booster output responsive rather than input responsive.

The overall structure of booster piston 5 is thus similar to that of FIG. It acts inside the hole 6. However, the valve device 12 is a two-part spool 40 and the spring 41 acts between an enlarged shoulder 42 at the rear end of the spool 40 and a step 43 in the bore 6 to move the spool rearwardly. The first spool portion 44 at the biasing front end has a port 45 permanently coupled to the inclined passage 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 . The spool part 49 is provided at its rear end with a diametrical passage 50 connecting said bore 48 with a chamber 51 in the part of the bore 6 on which the input member 7 acts. The pressure within the chamber 51 acts rearward on the input member 7;
1 has a passage 50 so that this pressure is constant,
Inner holes 48, 47, port 45, and inclined passage 23
It is always connected to the storage chamber 17 by.

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 32, a relief mechanism 39 consisting of a rubber block 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 arrangement 12 back to the input member 7 to produce a feeling of action on the pedal. Therefore, the present booster has the effect of increasing pressure on the first
It is an output response type rather than an input response type as shown in the figure.

The booster assembly of FIG. 2 is similar to that of FIG. 1 in which the assembled booster piston 5 is inserted into the housing 1 from the front end of the bore 2;
For this purpose, the sealing radius at the rear seal 16 is elastically deformed radially past the front seal 18, after which the 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 in the reservoir chamber 1.
Connected to 9. When a load is applied to the pedal, the input member 7 moves forward and the spool 40
is moved against the force of spring 41 into contact with block 56. Initially, the port 53 cuts off communication between the booster chamber 14 and the reservoir chamber 19,
Annular port 52 then opens into 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 applied to block 56.
and is transmitted via the output rod 36.

The reaction of the load applied to the master cylinder acts in a rearward direction and is transmitted through the output rod 36 to the block 56 causing it to deform. 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 or feel in the pedal.

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

If the input load is reduced, block 56 will force spool 40 rearwardly a further distance until the booster chamber 14 reaches an equilibrium position again.
This ensures communication between the storage chamber 19 and the storage chamber 19 again.

When the input load is completely removed, the spool 40
moves to post-equilibrium and converts the booster chamber 14 into the storage chamber 19.
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 shows a fluid action booster in longitudinal section, and FIG. 2 shows a further fluid action booster in longitudinal section. 10...Input rod, 11...Head, 12...
... Valve device, 13 ... Inner hole portion, 14 ... Booster chamber, 15, 16 ... Rear seal, 17 ... High pressure chamber, 18, 20 ... Front seal, 19 ... Storage chamber, 21 ... Seal Retaining ring, 22...O ring, 2
3... Inclined passage, 24... Passage, 25... Inclined passage, 26... Spool, 27... Spring, 28...
Port, 29... passage, 30... blind hole, 31...
Chamber, 32...Auxiliary piston, 33...Large diameter portion,
34... End member, 35... Spring, 36... Output rod, 37... Seal, 38... Seal, 39...
...relaxation mechanism, 40...spool, 41...spring,
42...shoulder part, 43...step part, 44...spool part, 45...port, 46...passage, 47...
Blind hole, 48... Inner hole, 49... Spool part, 5
0... Passage, 51... Chamber, 52, 53... Port, 54... Passage, 55... Passage, 56... Block, 63... Accumulator, 64... Working fluid reservoir.

Claims (1)

[Scope of Claims] A housing having an inner bore 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 piston having a stepped profile for acting within the bore and actuating the master cylinder assembly; a valve device is provided that is advanced in the bore in response to an increase in pressure in the chamber and controls the pressure condition of the booster chamber in response to a load applied to the input member; A hydraulic fluid booster for a vehicle braking system, the actuating fluid booster being operable to control communication between a section and a booster chamber and between the booster chamber and an outlet section, the hydraulic fluid booster comprising:
The bore and the diameter of the booster piston are configured and sealed to provide an annular chamber surrounding the booster piston and connected to the inlet, such that the booster piston at the rear end of the annular chamber is sealed.
The sealing diameter of the piston is larger than the sealing diameter of the booster piston at the front end of the annular chamber, and a radial gap is provided between the booster piston and the bore at the front end of the annular chamber. ,
A front seal between the inner bore and the booster piston at the front end of the annular chamber is arranged such that the front seal is radially deformable and the inner bore and the booster piston are radially deformable.
In the working fluid booster provided on the wall of the inner bore, allowing the passage of a relatively large rear sealing working diameter of the booster piston 5, so as to be able to absorb the radial gap between it and the piston. The front seal 18 is radially deformed so that the front seal 18 deforms radially and returns to sealing a relatively small front seal working diameter, thereby allowing the booster piston to be installed from the front end of the bore 2. A booster characterized in that said two sealing diameters of the booster piston 5 are selected to be . 2. The booster according to claim 1, wherein the front seal 18 is a polytetrafluoroethylene ring having an O-ring behind it. 3 the diameter of the inner bore 2 and the booster piston 5 form a second annular chamber 1 connected to the outlet 4;
9 is formed around the booster piston 5, and the front seal 18 is configured to seal between the high pressure annular chamber 17 and the second annular chamber 19. A booster according to claim 1 or 2.