JPH031184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a servo-booster assembly for a vehicle brake system for use with a master cylinder, and more particularly to a booster housing having opposed first and second housing walls; a master cylinder coupling member disposed on the first housing wall for coupling the housing wall to the housing of the master cylinder; and a master cylinder coupling member disposed on the second housing wall for coupling the second housing wall to a bulkhead of the vehicle. a movable wall disposed between the two housing walls and dividing the interior of the booster housing into two chambers; and a control valve assembly for controlling a pressure difference between the two chambers. and an output member operatively connected to the movable wall for actuating a piston of the master cylinder.

In recent years, there has been a worldwide shortage of fossil fuel resources, and the demand for them has been on the rise, so the need for fuel saving measures is increasing. Therefore,
For example, cars tend to be lighter. Consideration has been given to reducing the basic weight of the vehicle even slightly, even if this means slightly higher production costs. Even with the use of petroleum-based plastic materials, energy savings must be achieved by manufacturing lightweight automobile components.

For this reason, it has already been found that the housing of a servo booster assembly of the type described above can be made of plastic material. However, of the two housing members that make up the housing, the rear housing member is connected to the bulkhead of the vehicle, the front housing member is connected to the master cylinder housing, and the output member passes through the front housing member. In the configuration of
The output reaction force applied by the output member to the master cylinder piston is transmitted to the vehicle bulkhead through the two housing members of the servo booster assembly.

In such a construction, the thickness of the plastic material forming the housing member is increased to provide the required strength and stiffness, and the objectives of weight reduction and material savings cannot be achieved.

It is an object of the invention to significantly reduce the weight of the housing in a servo booster assembly of the type described above.

Original invention (Patent application No. 53-129422 [Tokukosho
No. 60-48379]) provides a servo-booster assembly of the type described above, in which at least one fixed force transmission member for transmitting axial force through the booster housing is connected to the first extending from a housing wall through the movable wall to the second housing wall, the movable wall being sealed directly or indirectly to the force transmitting member, and a first end of the force transmitting member; a portion is disposed adjacent to and rigidly connected to the master cylinder connecting member, and braking reaction force is directly transmitted from the housing of the master cylinder to the force transmitting member, When the servo booster assembly is activated, the first
at least a large portion of the housing wall of the second force transmitting member is adapted to be free from the braking reaction force;
an end portion of which is disposed adjacent to the vehicle bulkhead connecting member and is rigidly connected to the vehicle bulkhead connecting member, and braking reaction force is directly transmitted from the vehicle bulkhead to the force transmitting member, At least a large portion of the second housing wall is not subject to the braking reaction force during operation of the servo booster assembly.

When the servo-booster assembly of the present invention is mounted in a conventional manner between a master cylinder and a bulkhead of a vehicle, a force transmission member transmits braking reaction force from the master cylinder housing to the bulkhead of the vehicle.

The force transmitting member transmits substantially the front part of the axial force that is applied to the housing in conventional constructions, thereby reducing the strength and therefore the importance of the housing;
An overall reduction in weight is achieved, and play in the brake pedal due to deformation of the housing is significantly reduced.

The present invention is characterized in that, in the servo booster assembly for a brake system according to the original invention described above, a fluid passage is provided in the force transmitting member.

The fluid passageway may be used to provide fluid communication between one of the chambers and an external negative pressure source or compressed air line, or between one of the chambers and the control valve assembly. It can also be used to Further, in a skewer-type (tandem-type) servo booster, it can be used to communicate fluid between a pair of chambers.

Since the servo booster assembly for a brake system of the present invention utilizes the force transmission member as a member for providing a fluid passage, the structure is simplified and the weight is further reduced.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Referring to FIG. 1, the booster has a housing 1 formed from four stamped steel sheets 2-5. Opposing housing walls 2, 3
The outer peripheries of the housing walls 2 and 3 are connected by a cylindrical housing member 4, and the outer peripheries of the housing walls 2 and 3 are connected to the cylindrical housing member 4 by engaging molded portions 6 formed at intervals in the circumferential direction. It is done in this way. The pressed product 5 forms a partition wall 5 provided between the housing walls 2 and 3.

The first and second movable walls 7, 8 each consist of a diaphragm support plate 9, 10 formed into a dish shape that supports a flexible diaphragm 11, 12, respectively, and the outer peripheral edge of the diaphragm 11. The bead 13 connects the housing wall 3 and the housing member 4
The corresponding outer peripheral bead 14 of the diaphragm 12 is sandwiched between the housing wall 2 and the outer peripheral edge of the partition wall 5. The diaphragm support plate 10 has a press-formed steel plate tip 15 welded to the rear, and an inner peripheral edge bead 16 of the diaphragm 12 is sealed to the tip. The diaphragm support plate 9 supports a corresponding bead 17 of the diaphragm 11 with a central, rearwardly projecting tubular projection 18 that extends around the outer periphery of the head 19 of the generally cylindrical valve housing 20. engaged with;
A conical washer 21 pressed onto the tubular projection 18 holds the bead 17 in place.

First and second pressure chambers 22 and 23 are defined between the housing wall 3 and the partition wall 5 and the movable wall 7, respectively.
Second and third pressure chambers 24 and 25 are defined between the movable wall 8 and the movable wall 8, respectively. When the booster is inactive, the pressure chambers 22-25 are all connected to a negative pressure source, but when the booster is in operation, the pressure chambers 22, 2 on the rear side of each movable wall are
4 is connected to the atmosphere.

Force transmission member 2 arranged diametrically symmetrically
6, 27 are the entire housing, both movable walls 7,
8 and the fixed partition wall 5 in the axial direction. Each force transmission member includes an identical tube 28 extending between opposing inner surfaces of the housing walls 2, 3 and having two series of radial ports 29, 30 spaced apart in the axial direction. is provided. The ports 29, 30 of the force transmitting member 26 are in direct communication with the pressure chambers 23, 25, respectively, and the interior of the tube 28, together with the ports 29, 30, forms a fluid passage that constantly communicates the two pressure chambers 23, 25. The tubes 28 of the two force transmitting members are arranged in opposite directions, and the ports 20, 30 of the force transmitting member 27 constantly communicate with the ports 20, 30 of the force transmitting member 26 and the offset pressure chambers 22, 24. .

Diaphragms 11, 12 of the two movable walls 7, 8
Each of the two tubular portions 31 (sealing means) is integrally formed, and the annular bead 32 provided on the tubular portion 31 connects to the corresponding tube 28 of the force transmitting member.
is fitted into the annular groove 33 of the movable wall to seal the movable wall to the tube 28 of the bidirectional force transmitting member. The bulkhead 5 closes the tube 2 of each force transmitting member by an annular sealing member 34 held by a circular flange 35 projecting rearwards thereof.
8 is sealed.

During operation, the partition wall 5 moves rearward relative to the force transmission member tube 28 due to the pressure difference between the front and rear sides of the partition wall 5. This causes the rear surface of the sealing member 34 to engage with the annular groove of the force transmission member tube 28. This is blocked by a circlip 36 held in 37. Therefore, because of the presence of the force transmitting members 26 and 27, the partition wall 5 may have a relatively low strength and its weight can be reduced.

Each of the tubes 28 is closed at its rear end with a stud 38 (vehicle bulkhead connection member), and a screw provided on the rear outer surface of the stud 38 receives a nut for tightening the housing to the vehicle bulkhead. The housing wall 3 is fastened into sealing engagement with the rear end of the tube 28 by shear riveting.

The front end of the lower tube 28 (in the figure) is stud 39.
(master cylinder connecting member), the stud 39 is identical to the stud 38, but with a resilient annular seal 40 which effectively seals the housing wall 2 when the stud 39 is tightened to the housing 41 of the master cylinder. It is done like this.

Attached to the front end of the upper (as viewed) tube 28 is a tubular connector 42 which is connected to a negative pressure supply line (not shown).
The connector 42 is provided with a hexagonal head 43,
When tightening the housing 41 of the master cylinder between the head 43 and the housing wall 2, the connector 42 is gripped by the hexagonal head 43 and rotated. Seal 44 performs the same function as seal 40.

A tubular portion 47 extending rearwardly of the valve housing 20
An input member 45 passes through an air filter 46 held within and engages an input piston 48 of a known reaction assembly 49. Reaction assembly 49 includes a resilient reaction disk 50 and a head 51 of output rod assembly 52. The output rod assembly 52 is made up of two output members 53 and 54 connected by a spring pin 55 with the support plate 10 of the second movable wall 8 sandwiched between them, and the overall length of the output rod assembly is adjusted by a shim 56. do. A compression spring 57 acts between the front housing wall 2 and the support plate 10, applying a return force to both movable walls.

Poppet valve assemblies 58 of the known type include an axially compressible valve member 59 disposed between a first annular seat 60 at the rear end of the input piston 48 and a second annular seat 61 at the valve head 19. It is something that can be engaged. When the input member 45 is in the retracted position, the valve member 5
9 is an inlet 6 that engages with the first valve seat 60 and communicates with the atmosphere.
2 from the radial port 63 communicating with the pressure chamber 22 of the valve head 19, but the valve member 59 is separated from the second valve seat 61, and the pressure chamber 23 and the second valve seat 22 are connected via ports 64, 63. to communicate. Pressure chamber 2
2 is in permanent communication with the pressure chamber 24 via the interior of the tube 28 of the lower force transmitting member 27 and ports 29, 30, and the pressure chambers 23, 25 are likewise connected to the tube 28 of the upper force transmitting member 26. 28, all pressure chambers receive negative pressure (connector 42 is connected to the negative pressure supply line). When the input member 45 is moved forward, the valve head 59 separates from the first valve seat and moves to the second valve seat.
It engages the valve seat 61 and directs air at atmospheric pressure from the inlet 62 through the port 63 into the pressure chamber 22 and, therefore, into the pressure chamber 2.
Introduced in 4.

A seal assembly 65 retained within the rear end of housing wall 3 connects housing wall 3 to valve housing 20.
This seals the space between the diaphragm 6
6 serves as a seal between the partition wall 5 and the rod 53.

Similar to the structure described in the specification of patent application No. 53-129422 (Japanese Patent Publication No. 60-48379), which is the original invention, the force transmission members 26 and 27 transmit a reaction force from the master cylinder housing 41 to the partition wall of the vehicle. The housing wall 2 and housing wall 3 serve as a means for transmitting the information and restraining the housing wall 2 and the housing wall 3 from being separated from each other. Due to this force transmission element, the housing walls 2, 3 need be of relatively low strength and can therefore be lighter than conventional ones.

The shape of the outer periphery of the housing walls 84, 85 is such that the same housing wall can be used in a servo booster having only one movable wall.
In servo boosters with only one movable wall, the housing walls 84, 85 are connected directly to each other by corresponding molded parts and the housing member 86 is not required.

Referring to FIG. 2, the rear half of a skewer-shaped hydraulic master cylinder assembly 81 is fitted into a housing 82 of a pedal-operated skewer-shaped negative pressure servo booster 83. The booster housing 82 is
Front and rear plastic molded housing walls 84,
85 and an intermediate housing member 86 of plastic molding in which is integrally molded a partition wall 87 perpendicular to the axis of the booster. Housing walls 84, 85 and housing member 86 are 8
The flexible diaphragms 91, 9 of the front and rear movable walls 93, 94 are snap-engaged with each other at 8, 89.
It holds the outer peripheral bead of No.2.

The movable walls 93, 94 have annular diaphragm support plates 95, 96 of plastic molding, the support plate 95 of the front movable wall 93 being integrally connected with an axial sleeve 97 whose inner periphery extends forward; The support plate 96 of the side movable wall 94 is integrally formed with the substantially cylindrical valve body 98. Projecting rearwardly from the valve body 98 is a tubular extension 99 in which a boppet valve assembly 100 is housed. The valve body 98 slidably engages the outer surface of the extension 99 and the boot 10.
It is sealed to the rear housing wall 85 by an annular seal 101 integral with 2. The construction of the seal 101 and the boot 102 is the subject of Japanese Patent Application No. 1986-86808 (Japanese Unexamined Patent Publication No. 55-11993).

The booster housing is divided into four chambers 103-106 by movable walls 93, 94 and a fixed bulkhead 87.
It is divided into A pair of fixed force transmission members 10
7 (only one is shown) are housing walls 84, 85,
It passes through the partition wall 87 and both movable walls 93, 94 in the axial direction. Both force transmitting elements 107 are symmetrically diametrically opposed to each other with respect to the central axis of the booster. Each force transmitting member 107 includes a central tube 108 threadedly engaged at opposite ends with stud portions 109,110. Threaded ends 111 and 112 of the stud portion protrude outside the housing 83 and constitute connecting members that are connected to a flange 113 of a master cylinder housing 114 and a vehicle bulkhead (not shown), respectively.

The flexible diaphragms 91, 92 are identical, with rolling diaphragm portions 115, 116
are integrally molded, and the rolling diaphragm portion has annular beads 117, 118 that are seated in annular grooves formed in the outer surface of force transmitting member 107. The bead 117 sealingly abuts the rear end of a sleeve 119 that is integral with the front housing wall 84 to provide a seal between the front end of the force transmitting member 107 and the housing wall 84 and to connect the chamber 103 to the chamber 1.
It has been sealed since 2004. Bead 118 is chamber 105
and the chamber 106. Another annular seal 120 is provided on the stud 110 to seal the rear end of the force transmitting member 107 against the rear housing wall 85. The sleeve 119 supports the rolling diaphragm 115 when the front movable wall 93 moves forward, and the rolling diaphragm 116 of the rear movable wall 94 extends in the circumferential direction integrally extending rearward from the partition wall 87 of the housing member 86. It is supported by a series of spaced apart fins 121. Force transmission member 1
07 are each sealed to the partition wall 87 by an annular seal 122.

To provide permanent communication between chambers 104 and 106, force transmitting members 107 are each provided with annularly spaced radial through holes 123, 124;
Both force transmitting members 107 extend in the same direction, similar to the structure of FIG.

The master cylinder assembly 81 includes a primary piston 125 integral with a booster output member 126 and a secondary piston 127 connected to the primary piston by a lost motion connection 128, both pistons being connected by a coil spring 129. separated from each other. An annular seal assembly 130 held in a counterbore at the rear end of master cylinder housing 114 by a U-shaped wire retainer 131 controls the retracted position of primary piston 125 and, therefore, the retracted position of secondary piston 127. The force acting as a determining stopper and retracting the primary piston is generated by the step 133 of the master cylinder housing 114 at the front end.
The flange 1 of the button 135 is in contact with the flange 1 of the button 135 and its rear end is fixed to the rear end of the output member 126 by a dimple 136.
34 is provided by a coil spring 132 that abuts.

The stepped tubular member 137 has a large diameter portion 138 and a small diameter portion 139, and the large diameter portion 138 is connected to the output member 1.
26 and has a forward end flange 140 extending radially outwardly and an outwardly swaged portion 141 that fits into a counterbore 142 in the inner diameter of sleeve 97. It is fixed. O-ring 123 acts as a seal between sleeve 97 and tubular member 137 to seal chambers 103 and 10.
4 and the large diameter portion 1 of the tubular member 137.
The annular seal 144 disposed in an annular groove 145 integral with the partition wall 87 of 38 is slidably sealed against the partition wall 87.

The outer diameter of the reduced diameter portion 139 of the tubular member 137 slidably fits within the aperture portion 146 at the front end of the valve body 98, and the inner diameter has the head of the button 135 slidably fitted therein. A flange 147 provided inside the small diameter portion 139 is a pedal operation input member 1.
A front end 148 of a valve control member 149 connected to the head of the valve control member 50 defines a hole into which the front end 148 of the valve control member 149 is slidably fitted.

The rear end of the valve control member 149 and the valve body 98 are formed in a conventional manner with coaxial valve seats 121, 122 for engagement by an annular portion of a poppet valve assembly 100.

Permanent communication between the chambers 103 and 105 is provided by a series of circles provided within the large diameter portion 138 of the tubular member 137 and at the step between the large diameter portion 138 and the small diameter portion 139 of the tubular member 137. This is done by circumferentially spaced axial holes 154. Because the inner diameter of the large diameter portion 138 of the tubular member 137 is relatively large, the passageway 155 in the valve body 98 allows the poppet valve assembly 110 to change the pressure in the chamber 105.
It takes almost no time to equalize the pressures in chamber 105 and chamber 105.

It should be noted that the movable walls 93, 94 are not rigidly connected to each other. Even if the rear movable wall 94 becomes stuck in the housing, the front movable wall 93 can still move axially relative to the rear movable wall, so that the front wall 93 will still be boosted. It can give you strength. An O-ring 126 is disposed in an annular groove in the outer diameter of the reduced diameter portion 139 of the tubular member 137 to provide a slidable seal between the reduced diameter portion 139 and the valve body 98 and to provide a slidable seal between the reduced diameter portion 139 and the valve body 98 .
Both movable walls 93 and 94 are movable relative to each other with the chamber 106 and the chamber 106 sealed together.

The coil spring 132 connects both pistons 125 and 127
However, in addition, both movable walls 93, 94
It is recognized that it is also useful for returning the person to the retreated position. This feature is described in detail in Japanese Patent Application No. 13471/1983 (Japanese Patent Application Laid-Open No. 54006/1983).

In the embodiment of FIG. 3, parts corresponding to those of FIG. 2 are given the same reference numerals.

Turning to FIG. 3, the main differences between that structure and the structure of FIG. A plurality of reinforcing ribs 160 are provided inside the large diameter portion 138 at intervals in the circumferential direction and extending in the axial direction,
Second, the large diameter portion 138 of the tubular member 137 is provided with a plurality of circumferentially spaced ports 154;
The difference is in the manner in which 53 is confined. In this embodiment, the reduced diameter portion 139 of the tubular member 137 is closed at its rear end with a wall 161 which is slidable directly into the bore 146 of the valve body 98 and has a reaction disk 153 of the resilient member. , rear end wall 161, hole 146
It is confined by the sleeve 162 therein and the forward end 148 of the valve control member 149 . A unitary head 135' is provided at the rear end of the output member 126, and the head is connected to the reduced diameter portion 139 of the tubular member 137.
The rear end wall 161 is engaged with the rear end wall 161 via a metal shim 163.

The force generated by the front movable wall 93 is the force generated by the rear end wall 161.
is directly transmitted to the output member 126, and the reaction disk 153 does not receive this force. The reaction disk 153 receives only the forces generated by the rear movable wall 94. This force is transferred to the output member 126 through the sleeve 162, the reaction disk 153, and the rear end wall 161.
transmitted to.

The pressure created in the elastic disk 153 therefore acts on the front end 148 of the valve control member 149 and provides a reaction force on the input member 150. This pressure is caused by the force generated by the rear movable wall 94 and has nothing to do with the force generated by the front movable wall 93. Therefore, the same members 85, 94, 98, 153, 162,
149 can be used.

In the configuration of FIG. 3, reaction disk 153 provides a seal between chambers 105 and 106, so that a seal corresponding to O-ring 156 of FIG. 2 is not provided.

In the modified embodiment shown in FIG. 4, the same reference numerals are given to parts corresponding to those in the embodiment shown in FIGS. 2 and 3. The configuration of FIG. 4 is similar to that of FIG. 3 in that the tubular member 137 is integral with the sleeve 97 of the front movable wall 93, but as in FIG. 93 and 94 transmit the sum of the forces generated.

[Additional relationship]

Original invention (Patent Application No. 129422 (1984))
No. 48379] is a servo-booster assembly for a vehicle brake system for use with a master cylinder, the booster housing having first and second opposing housing walls; a master cylinder coupling member provided on the first housing wall for coupling to the master cylinder housing;
a vehicle bulkhead connecting member provided on the second housing wall for connecting the second housing wall to the vehicle bulkhead; and a vehicle bulkhead connecting member disposed between the two housing walls to divide the interior of the booster housing into two chambers. an input member for actuating a control valve assembly for controlling a pressure differential between the chambers; and an output member operatively connected to the movable wall for actuating a piston of the master cylinder. a servo-booster assembly for a vehicle brake system having at least one fixed force transmission member for transmitting axial force through the booster housing, the at least one fixed force transmission member extending from the first housing wall through the movable wall; and extending to the second housing wall, the movable wall being directly or indirectly sealed to the force transmitting member, the first end of the force transmitting member being adjacent to the master cylinder coupling member. actuating the servo-booster assembly by directly transmitting braking reaction force from the master cylinder housing to the force transmitting member; wherein at least a majority of the first housing wall is free from the braking reaction force, and the second end of the force transmitting member is disposed adjacent to the vehicle bulkhead connection member; at least a large portion of the second housing wall during actuation of the servo-booster assembly is rigidly coupled to a vehicle bulkhead connection member and transmits braking reaction forces directly from the vehicle bulkhead to the force transmission member. A servo booster assembly characterized in that the portion is configured so as not to receive the braking reaction force described above. However, the present invention is an invention in which all of the matters essential to the structure of the original invention are made into main parts of the matters essential to the structure, and it achieves the same purpose as the original invention. be.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a booster according to an embodiment of the present invention, showing a state in which the input member and the movable wall are in the retracted position. FIG. 2 is a longitudinal cross-sectional view of a skewer-shaped servo booster connected to a skewer-shaped hydraulic master cylinder according to an embodiment of the invention, with the upper force transmitting member placed in a vertical plane for illustrative purposes. , each part is in the retracted position. 3 and 4 are similar longitudinal sectional views showing modifications of the booster of FIG. 2, respectively. DESCRIPTION OF SYMBOLS 1... Housing, 5... Partition wall, 7, 8... Movable wall, 22-25... Chamber, 26, 27... Force transmission member, 28, 29, 30... Fluid passage.

Claims (1)

Claims: 1. A servo-booster assembly for a vehicle brake system for use with a master cylinder, comprising opposed first and second housing walls 2;
3; a booster housing having 84, 85; a master cylinder connecting member 39; 111 provided on the first housing wall for connecting the first housing wall to the housing 41, 114 of the master cylinder; a vehicle bulkhead connection member 38 provided on the second housing wall for connecting the second housing wall to the vehicle bulkhead;
112; a movable wall 7 disposed between the housing walls and dividing the interior of the booster housing into two chambers; 94; and an input for actuating a control valve assembly for controlling the pressure difference between the chambers. Part 4
5; 150; and an output member 54; 126 operatively connected to said movable wall for actuating a piston of said master cylinder and for transmitting an axial force through said booster housing. one fixed force transmission member 26, 27;
107 extends from the first housing wall through the movable wall to the second housing wall, the movable wall being sealed directly or indirectly to the force transmitting member and transmitting the force. A first end of a transmission member is disposed adjacent to and rigidly connected to the master cylinder coupling member, and a braking reaction force is transmitted from the master cylinder housing to the force transmission member. The direct transmission causes at least a majority of the first housing wall to be free of the braking reaction force during actuation of the servo booster assembly, and the second end of the force transmitting member is The servo booster is disposed adjacent to the vehicle bulkhead connecting member and is rigidly connected to the vehicle bulkhead connecting member, so that braking reaction force is directly transmitted from the vehicle bulkhead to the force transmitting member. In a servo booster assembly for a brake system, in which at least a large portion of the second housing wall is not subjected to the braking reaction force during operation of the assembly, the force transmitting members 26, 27; fluid passageway 28, 29, 30; 108, 1
23 and 124, the servo booster assembly is characterized in that the servo booster assembly is provided with air passages 23 and 124 to allow air to flow into the one chamber through the fluid passageway during operation. 2. A servo-booster assembly for a vehicle brake system for use with a master cylinder, the assembly comprising opposed first and second housing walls 2,
3; a booster housing having 84, 85; a master cylinder connecting member 39; 111 provided on the first housing wall for connecting the first housing wall to the housing 41; 114 of the master cylinder; a vehicle bulkhead connection member 38 provided on the second housing wall for connecting the second housing wall to the vehicle bulkhead;
112; a movable wall 7 disposed between the housing walls and dividing the interior of the booster housing into two chambers; 94; and an input for actuating a control valve assembly for controlling the pressure difference between the chambers. Part 4
5; 150; and an output member 54; 126 operatively connected to said movable wall for actuating a piston of said master cylinder and for transmitting an axial force through said booster housing. one fixed force transmission member 26, 27;
107 extends from the first housing wall through the movable wall to the second housing wall, the movable wall being sealed directly or indirectly to the force transmitting member and transmitting the force. A first end of a transmission member is disposed adjacent to and rigidly connected to the master cylinder coupling member, and a braking reaction force is transmitted from the master cylinder housing to the force transmission member. The direct transmission causes at least a majority of the first housing wall to be free of the braking reaction force during actuation of the servo booster assembly, and the second end of the force transmitting member is The servo booster is disposed adjacent to the vehicle bulkhead connecting member and is rigidly connected to the vehicle bulkhead connecting member, so that braking reaction force is directly transmitted from the vehicle bulkhead to the force transmitting member. In a servo booster assembly for a brake system, in which at least a major portion of the second housing wall is not subjected to the braking reaction force during operation of the assembly, the movable wall 7; A second movable wall 8; 93 is provided at a distance from the movable wall so as to apply an axial force to the output member 54; 5; 87 and arranged in the axial direction 4
A second chamber 22-25; 103-106 is defined within the housing by the partition wall and the movable wall.
means 31; 115 for sealing the movable wall of the chamber to said force transmitting member 26, 27; ,30;108,12
3,124. A servo booster assembly comprising: 3,124.