JPS6048379B2 - Servo booster assembly for vehicle brake system - 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 Z for actuating the piston of the master cylinder. It concerns a booster assembly.

BACKGROUND ART Recently, fossil fuel resources have become unstable worldwide, and the demand for them has tended to continue to increase, so there is an increasing need for fuel saving measures.

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 this configuration, the output reaction force applied by the output member to the piston of the master cylinder is transmitted to the bulkhead of the vehicle 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 rigidity, 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.

The present invention 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 extends from the first housing wall upwardly. extending through a movable wall to the second housing wall, the movable wall being sealed directly or indirectly to the force transmitting member, the first end of the force transmitting member being connected to the master. The servo booster is disposed adjacent to the cylinder connecting member and is rigidly connected to the master cylinder connecting member, so that braking reaction force is directly transmitted from the housing of the master cylinder to the force transmitting member. At least a majority of the first housing wall is free from the braking reaction force during actuation of the assembly, and the second end of the force transmitting member is disposed adjacent the vehicle bulkhead connection member. ,and,
at least one of the second housing walls upon actuation of the servo-booster assembly is rigidly connected to the vehicle bulkhead connection member, and braking reaction force is transmitted directly from the vehicle bulkhead to the force transmission member. Most of them are characterized by being designed so as not to receive the above-mentioned braking reaction force.

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.

Since the force transmitting member transmits substantially all of the axial forces that would otherwise be applied to the housing in conventional constructions, the strength and therefore the importance of the housing can be reduced, resulting in an overall reduction in weight. The force transmitting member has both ends passing through the housing wall and being connected directly to an external member, or is connected to a portion of the housing wall, and has means for connecting to an external member at an adjacent portion of the housing wall. It's okay.

In the latter case, the part of the housing near one end of the force transmitting member will transmit all of the reaction force between the external member and the force transmitting member, so the cuff part of the housing must be made sufficiently strong. No. However, other parts of the housing can be made relatively thin. If the force transmitting member projects from both walls of the housing and is connected directly to an external member, there is no need to fasten the housing to the force transmitting member 5 material.

In that case, the walls of the housing are simply suspended from the force transmitting member. The need to seal the movable wall in some way to the force transmitting member to prevent fluid communication between the two booster chambers is a corollary of the insertion of the force transmitting member.

This sealing can be done in a conventional manner, but need not be done directly to the force transmitting member. For example, the movable wall can be sealed to the inner surface of one housing wall by an annular seal that surrounds but does not engage one end of the force transmitting member. Preferably, each force transmitting member comprises a pull bar.

Although in some cases one pull bar is sufficient, more than one pull bar is usually used. Each tension bar may be of circular cross-section, although other suitable cross-sections of tension bars may be used.

The tension rod may be hollow. Each sealing means may comprise a seal supported on the movable wall and slidingly engaged with the drawbar, or a rolling diaphragm member affixed to the movable wall and the drawbar.

Preferably, each pull bar laterally displaces the movable wall from an axis passing through the center.

If a plurality of drawbars are used, they are preferably equally spaced circumferentially about the axis.

Preferably, two pull rods are used and are arranged symmetrically about the axis.

When two tension rods are used, the servo booster assembly is mounted so that, in use, the plane approximately containing the two tension rods is oriented at any angle between 0° and 90° to the vertical. can.

Each force transmission member can consist of only one part, but can also consist of several parts connected to each other.

The drawbar can consist of a straight member, but can also have bent portions such that the ends are laterally displaced relative to each other.

The bent portion can be located inside or outside the booster housing or within one wall of the housing.
Preferably, the movable wall comprises a flexible diaphragm and a diaphragm support plate, and the force transmitting member extends through the diaphragm support plate.

When the movable wall comprises a flexible diaphragm, the movable wall is preferably sealed to the car transmission member by rolling portions of the guiaphragm, each rolling portion being preferably integral with the main diaphragm.

Preferably, the housing is constructed from a pair of opposed housing members, with the housing l-wall being a wall formed by each housing member.

In conventional servo booster assemblies, a pair of members are rigidly connected together by swaging their outer rims.

However, in the servo booster assembly of the present invention in which the housing comprises a pair of opposing housing members, the force transmitting member may constitute a means for holding the two housing members in a clamped condition. The servo·
Supplemental fastening means may be provided on the outer periphery of the housing members to hold the pair of housing members in engagement with each other prior to installation of the booster assembly in a vehicle; There is no need for the fastening means to be as strong as the fastening means used. The radial outer peripheries of the pair of housing members snap into engagement with each other when assembled by relative axial movement of the members. In the servo booster assembly of the present invention, at least one of the pair of housing members can be made of a transparent plastic material. The generally low strength of transparent plastic materials precludes the use of such materials in conventional servo booster assemblies. A servo booster assembly made of at least a portion of transparent plastic material allows the servo booster assembly to be assembled by an automated robot because the assembled components within the housing can be visually inspected to some extent. Where the housing is comprised of a pair of opposing housing members, the front housing member located adjacent the master cylinder in use is preferably transparent, and this housing member is preferably transparent. It is preferable to integrate it with

In a servo booster assembly, it is important to precisely position the free end of the booster output member relative to the input member of the master cylinder to which the servo booster assembly is connected in use.

The master cylinder housing is generally a servo. Positioned against the outer surface of the forward housing member of the booster assembly, the output member of the servo booster assembly generally has a length adjustment mechanism that controls the length and therefore the axial position of the free end of the output member. It is necessary to provide some means of relative adjustment to the front housing member. The incorporation of such adjustment means and adjustment operations are expensive.
Embodiments of the present invention will be described below with reference to the accompanying drawings.

The servo booster assembly shown in FIGS. 1 and 2 includes a housing 10. The servo booster assembly shown in FIGS.

The housing 10 includes two generally cup-shaped members 12,
14, and the outer peripheries of both members engage with each other! A thickened outer peripheral bead portion 16 of an elastic diaphragm 18 is tightened therebetween. The inner peripheral edge 20 of the diaphragm 18 is tightly fastened by a ring 25 within a slot 22 provided in the outer periphery of an annular support plate 24 . The support plate 24 and the diaphragm 1.8 divide the interior of the housing 10 into two chambers 26,28. The servo booster assembly includes a poppet valve arrangement 30.

The poppet valve assembly 30 includes a generally cylindrical valve body member 32 extending axially of the housing 10 and having a bore 34 therein. The bore 34 in the valve body member has sections of different diameters, with the smallest diameter section 36 slidably receiving a cylindrical thrust member 38 with a valve actuation rod 42 at the rear end of the thrust member. A ball socket 40 is formed to accommodate a ball formed at the front end. The front end of the thrust member 38 projects from the valve body member 32 toward the rear side of the rubber disk 44 . On the front side of the disc 44 is an output rod 48 extending to a brake master cylinder (not shown).
The flanged ends 46 of are engaged. The flanged end 46 of the output rod and the disc 44 are positioned relative to the valve body member 32 by a generally cup-shaped retaining plate 50 that is retained within a cylindrical inner peripheral portion 52 of the annular support plate 24. A main coil spring 54 acting between the plate 50 and the housing member 14 presses the front end of the valve body member 32 . An axially flexible valve closing member 58 is disposed within the intermediate portion 56 of the bore 34 of the valve body member 32, and the thicker rear end of the valve closing member 58 is connected to the clamp 60 and the valve actuator 42. It is held tightly against the internal bore 34 by a coil spring 62 acting between an attached collar 64.

The forward end of the valve closure member 58 also defines a thick, flat, radially extending surface 66 which is connected to the valve body member 3.
2 (outer cylindrical valve seat 68 and thrust member 38 formed in
It cooperates with an inner valve seat 70 formed at the rear end of the valve. An annular reinforcing ring 72 is embedded in the thicker front end of the valve closing member, and acts between the front end and the clamp 60 on the inner periphery of the front end. A coil spring 76 is engaged that presses the valve toward the valve seat. The rear end of the bore 34 of the valve body member communicates with the atmosphere through an air filter 34'.

The outer valve seat 68 communicates with the front chamber 26 of the housing through a passage 78 provided in the thickened front portion 80 of the valve body member 32 and a hole 82 provided in the retaining plate 50. . The rear chamber 28 of the housing communicates with a chamber 86 located in front of the inner valve seat 70 via a passage 84 provided in the valve body member 32 . The valve body member 32 is the housing 1
A fluid-tight seal 86' is disposed around the valve body member 32 within a rearwardly extending cylindrical extension 88 of the housing member 12 to permit axial sliding relative to the housing member 12. A flanged reinforcing ring 88' is embedded in this seal 86' and is fastened to the valve body by a ring 90. Seal 86' is protected from dirt and foreign material by a flexible rubber boot 92. This boots 9
The forward end of 2 connects to the cylindrical extension 88 of the housing member 12 and the rear end 13 connects to the rearmost end of the valve body member 32. The rear end of the boot 92 may be connected directly to the stem of the valve actuation rod 42. In this latter case, it will be necessary for the gate boot to have an aperture to provide communication between the bore 34 of the valve body member and the atmosphere as described above. The servo booster assembly described above operates in a conventional manner as follows.

When the servo booster assembly is in its inactive state (FIG. 1), the thrust member 38 is urged to the right in FIG.
5 engages the surface 66 of the valve closing member 58 and pushes the thicker front portion of the valve closing member to the right. Under this condition, the rear chamber 28 of the housing is isolated from the atmosphere by the first poppet valve formed by the valve seat 70 and surface 66 described above. Both chambers 26, 28 of the housing have holes 82, passages 78, chambers 86 and passages 84.
and a second valve formed by the outer o-side valve seat 68 and the surface 66.
and a poppet valve. When the servo booster assembly is in this state, both chambers 26, 28 of the housing are connected to a source of negative pressure via a negative pressure source connection 89 (FIG. 2) in the wall of the housing member 14; The servo booster assembly is under negative pressure. When the valve actuating rod 42 is moved to the left, for example by depressing a pedal, the thrust member 38 similarly moves. During this movement, initially the first poppet valve remains closed due to the action of the spring 76. When the valve closing member surface 66 engages the outer valve seat 68, it also closes the second poppet valve and isolates both chambers 26, 28 of the housing from each other. Further leftward movement of the thrust member 38 causes the valve seat 70 to move away from the surface 66 and open the first poppet valve to open the rear chamber 2 of the housing.
8 to the atmosphere. The pressure difference created before and after the diaphragm 18 and the support plate 24 displaces the support plate 24 to the left against the force of the main coil spring 54, and this movement causes the output rod 4 to displace the support plate 24 to the left.
8 to operate a master cylinder (not shown). The degree of the pressure difference created across the diaphragm 18 and the support plate 24, and therefore the power applied to the brake, depends on the degree of opening of the first poppet valve formed by the valve seat 70 and the surface 66 of the valve closing member 58, i.e. It depends on the degree of axial movement of the valve actuation rod 42. During the above-described operation of the servo booster assembly, the housing is subjected to stress due to the negative pressure conditions of the two chambers within the housing and stress due to the reaction forces of the various moving parts.

This stress has traditionally been supported by making the housing members 12,:14 from relatively thin but heavy materials, or by constructing them from light but relatively thick materials. In the illustrated embodiment, such stresses are applied to two housing members 12.
, 14 to connect these two members to each other. 2 parallel to the axis of the star assembly
Book tension rod 100 (only one shown in Figure 1)
By being supported by a force transmitting member in the form of , the housing member can be made of light and relatively thin material. Each pull rod 100 slidably passes through the support plate 24 relative to each other during operation of the servo booster assembly.
The support plate 24 can be freely displaced in the axial direction. In this embodiment, the pull rod 100 passes through a corresponding hole 102 in the support plate 24, and a flexible seal 4 (104) is press-fit between the pull rod 100 and the hole 102. A stiffener 106 and a tightening ring 108 can be included. The seal 104 can also form a grease pocket. The seal 104 has one end attached to the support plate 24 in a corresponding hole 102 and the other end attached to the housing. A flexible boot attached to the drawbar 100 in the front chamber 26 could also be substituted.

In the embodiment of FIG. 1, the right end of the drawbar 100 is permanently attached to the enlarged portion 103 of the right housing member 12 during its molding.

The flattened portion 105 of the tension bar 105 prevents rotation of the tension bar relative to the housing member. The left end of the tension rod 100 is a thickened portion 1 of the housing member 14.
08' through a corresponding hole 106', e.g.
O-ring seal 110 seals to hole 106'. As shown in FIG.
12 and the shoulder 114 when the threaded ends 116, 118 of the drawbar 100 pass through a suitable mounting plate and are attached to the mounting plate by a suitable nut 143; It can be selected to be slightly shorter than the overall length of the housing so that the two housing members 12, 14 are clamped together. The right threaded end 118 of the drawbar 100 passes through and is secured to the vehicle bulkhead, and the left threaded end 116 is secured to a flange 140 at the rear end of the housing 141 of the brake system master cylinder. It is preferable.
In this manner, housing members 12, 14 only have a tendency to flex inwardly when negative pressure is applied, which creates input and output stresses. With the construction described above, the two housing members are not tightened together until the servo booster assembly is fitted into the mounting position between the master cylinder and the bulkhead, so for transportation and storage purposes, the two housing It is necessary to provide means for holding the parts together so that they do not separate from each other.

This can be done in several ways. For example, the surface of the hole 106 through which the drawbar 100 passes can be provided with a resilient member that snaps into a corresponding circumferential groove in the surface of the drawbar. Alternatively, the two housing members can be adhesively bonded together at a point radially outward of the outer peripheral bead portion of the diaphragm 18. In a further locking method, the two housing members form engagement surfaces that snap-fit together as shown in FIG. A local reinforcement is provided in a part of the housing member 12 (or 14), one end of the draw rod 100 is connected to the reinforcement, and a connection member (stat 120 or 122) to the vehicle bulkhead or master cylinder is connected to the reinforcement. It may be connected to the reinforcing part.

A stud 120 in FIG. 4 is connected to a reinforcing portion of the housing member 12 by press fitting, and a stud 122 in FIG. 5 is connected to a similar reinforcing portion by molding. The tension rod 100 is rigidly connected to the stud 12 or 122 via local reinforcement of the housing member. In this structure, the tension rod 100 and the connecting members (stats 120, 12
2) can be slightly deviated laterally. As shown in FIG. 6, the force transmitting member may be composed of multiple parts. In the construction of FIG. 6, the housing members 12, 14 are made of sheet metal, and the drawbar 100 is provided with a threaded end 118 at its rear end that projects from the housing member 12 and is connected to the bulkhead of the vehicle. There is. Front end 146 of drawbar 100
A metal bracket 145 is riveted to and extends laterally. A short pull rod 147 is riveted to the bracket 145 at a position laterally displaced from the pull rod 100. A short pull rod 147 is inserted into the hole 149 in the housing member 14.
, with its threaded end 148 projecting forward. The drawbar 147 is connected to the housing member 14 and the shoulder 151 formed on the drawbar 147 and the front surface 1 of the bracket 145.
It is sealed to the housing member 14 by an annular elastic seal 150 sandwiched between the housing member 52 and the annular elastic seal 150 . In use, an annular resilient seal is also placed around the end 118 of the drawbar and in contact with the housing member 12 to seal the rear chamber 28 of the housing. The structure of FIG. 6 allows the pair of short pull bars 147 secured to the master cylinder housing to be spaced less than five spacings apart from each other in the pair of draw bars 100 in use.

This may be necessary, for example, to create sufficient space for the valve body member 32. In another variation (not shown), the bracket 145 is located externally to the housing member 14. If necessary, brackets can be provided at both ends of the drawbar. Still referring to FIG. 6, the movable wall of the servo booster has an inner circumferential annular beam 15 sealed in an annular groove 155 in the pull bar 100.
4 and a peripheral bead 156 having a groove on its outer surface that sealingly fits into the inner peripheral edge of the support plate 24 surrounding the hole 157.

A modification of the drawbar 100 is shown in FIG.

The drawbar is provided with a pair of axially spaced outwardly facing shoulders 112, 158, the spacing of which is equal to the distance between the inwardly facing shoulder 124 and the front surface 159 of the housing member 14. The shoulder 158 is therefore located forward of the front face 159 to engage the flange of the master cylinder housing. Housing member 14 is not subject to clamping forces between master cylinder and drawbar 100 in this case. The drawbar 100 can be provided with such protruding shoulders 158 at both ends, if desired.
In use, the negative pressure applied is applied to the housing members 12, 14.
This creates a force that crushes the guafram bead 16 inwardly, thus increasing the clamping and sealing force on the guaflamm bead 16.

Collapsing of the housing is prevented in the embodiment of FIG. 1 by engagement of shoulder 124 of housing member 14 with shoulder 112 of drawbar 100. As previously mentioned, conventional servo booster assemblies deflect under loads transmitted through the housing member itself.

As a result, at high input levels there is a movement in the brake pedal, and to compensate for this the permissible stroke J of the brake pedal must be increased. Since the housing member of the above-described construction according to the invention is not stressed by inputs and outputs, the housing member can be thinner and therefore lighter than conventional ones. The drawbar itself can be made of any material with sufficient stiffness to limit deflection under load to an acceptably low stiffness value.

Metal materials such as steel or aluminum can meet this requirement. The present invention is not limited solely to directly actuated types of servo booster assemblies in a single housing, but also to tandem units or remotely actuated (
For example, it can also be applied to embodiments that are hydraulically controlled.
Housing members 12, 14 need not necessarily be made of plastic material.

It could also be made of metal, such as aluminum, but would require a drawbar retention means other than molded. FIG. 3 shows an alternative embodiment in which the ends of the drawbar 130 are slidably received in corresponding holes 132, 134 in the housing member.

The ends of the drawbar are sealed by seals 136, 138, and the drawbar is prevented from rotating by suitable flat surfaces.
In place of the threaded ends 116, 118 of the drawbar, an externally threaded member threaded into an internally threaded hole opening in the drawbar end surface substantially flush with the outer surface of the housing members 12,14 may be used.

The servo booster assembly of FIG.
A snap fit is made at the point indicated by 3, enclosing a peripheral bead 164 of approximately trapezoidal cross section of the flexible diaphragm 1.165 therebetween.

A pair of metal pull rods 166 extend axially through the housing member and a plastic molded diaphragm support plate 167.

A pair of drawbars are disposed on one diameter of the housing on opposite sides with respect to the housing axis, and the diaphragm 165 is preferably disposed equidistant from the output bar 180 with the axes of their tensionbars disposed at the same distance from the output bar 180. and a pair of rolling portions 169, the rolling portions 169
seals the diaphragm 165 to a first sleeve 170 that is slidable with the housing member 161 relative to the central portion 171 of the drawbar 166 .

The outer surface of the first sleeve 170 is guiafra. It is smooth to form a support surface for the rolling portion 169 of the drum. A fifth sleeve 172 is integrally provided with the housing member 161 and has a free end spaced apart from a free end of the first sleeve 170. The drawbar 166 has threaded reduced diameter ends 173, 174 that connect to the vehicle bulkhead and master cylinder, respectively.

Pull rod shoulders 175, 176 project from adjacent outer surfaces of the housing member and engage the surfaces of the master cylinder and bulkhead 4, respectively. In the structure of FIG. 9, the rolling portion 169 of the diaphragm is supported by a sleeve 170 that is integral with the rear housing member 161.
In this embodiment, the sleeve 170 extends slidably through the front housing member 162, which is not provided with a sleeve.

The outer surface 178 of the front housing member 162 is connected to the sleeve 17.
A conical opening is provided around 0. The servo.
an annular housing engagement surface 182 and a recessed output rod free end engagement surface 183 for setting the axial position of the free end of the output rod 180 relative to the housing members and internal components of the booster assembly; The positioning tool 181 is
Gradually move it to the right in the figure.

The housing engagement surface 182 of the tool 181 engages the housing member 1 before the output rod free end engagement surface 183 engages the output shaft.
62 to press the radially inner portion of the housing member 162 toward the radially inner portion of the housing member 161 by utilizing the elasticity of the housing portions 161 and 162. When the engagement surface 183 engages the output rod 180, the output rod is properly axially positioned relative to the outer surface 178 of the front housing member 162. A welding tool having an annular welding head 184 is then pressed against the free end of the sleeve 170 and welded to the housing member portion 179 thereby establishing the axial spacing between the central portions of the housing members 161,162. Servo in Figure 10
No sleeve is provided around the drawbar 166 in the booster assembly.

Each drawbar 166 has a recessed and splined portion 185 around which the rear housing member 161 is molded between each drawbar 166 and the rear housing member 161. Forms a solid connection. The front housing member 162 is molded with a pair of inserts 186 consisting of a large diameter rear portion 187 with recesses and serrations and an initially smooth cylindrical front portion 188 in symmetrical positions with respect to the housing axis. ing. A portion 189 of the draw rod 166 passing through the insert 188 can initially be slid within the hole in the insert 186 to enable assembly of the two housing members 161, 162. After the housing members are assembled, the axial position of the front surface 178 of the housing member 162 is adjusted relative to the free end of the output rod 180 by applying a sufficient axial force to the front surface 178 to Portion 188 is compressed and engages three circumferential grooves 190 in portion 189 of each drawbar 166 . The servo booster assembly of FIG. 11 is similar to that of FIG. 8 in that the plastic molded housing members 161, 16:2 each have an integral sleeve 170, 172 around the pull rod 166. However, in this example, sleeve 1
70 and 172 have almost the same length.

Each pull bar 166 has a smooth cylindrical enlarged diameter section 191,19
2, 19.3, an enlarged diameter portion 194 provided with splines, a smooth reduced diameter portion 195, and a reduced diameter portion 196 provided with splines of considerable length. Part 192,
A sleeve 170 is molded around 196. Sleeve 1 is assembled using sections 192 and 196 by press-fitting pull rod 166 after molding the housing member.
Complementary splines may be formed on the inner cylindrical inner surface of 70. Splined portion 196 has a significant length so that pull bar 166 is positioned relative to housing member 161.
It does not rotate. Sleeve 172 is formed with a stepped hole, the step 198 of which abuts portion 191 of the drawbar so that the central portions of housing members 161, 162 are brought closer together by the negative pressure applied during use. The axial position of the center portion of the housing member when pressed in this manner is determined. At the end 199 of the sleeve 172 is a portion 194 of the drawbar 166.
When the tension rod 1 is press-fitted, a spline is formed on the inner surface, and the tension rod 1
66 cooperates with the spline of section 194. The diaphragm 165 has a rolling portion 200 terminating in a bead 201 wedge-shaped in cross section, the bead 201 increasing in axial width with decreasing diameter and formed between portions 192 and 194 of the drawbar 166. It is seated at the bottom of the annular recess 202.

The thin radial exterior of the bead 201 is clamped to the free ends of the sleeves 170, 172 to prevent it from being pulled radially away from the pull bar 166 when a high pressure differential is applied to the diaphragm. has been done. However, the free ends of the sleeves 170, 172 are spaced apart in the axial direction so as not to apply a tightening force to the bead that would damage the bead. As shown, the surface of the bead 201 that engages the pull rod 166 can be provided with a return recess, but this surface can also be flat. Sleeve 170,1
72 and to avoid excessive axial compression of the radial overhang of the bead 201 (the radial overhang of the bead 201 is rolling portion 200 may become distorted), it may be necessary to compress bead 201 radially between pull bar 166 and sleeves 170, 172.

It should be noted that the bead 201 not only seals the two chambers of the booster together, but also seals between the drawbar and the two housing members, thus requiring a separate seal at the end of the drawbar. That means no. The drawbar 166 is located near its forward end at a front surface 178 of the housing member 162.
A step portion 202 is provided which is axially displaced from the axial direction.

The step 202 also forms an abutment against the rear end surface of the master cylinder housing. The housing member 162 is provided with a skirt 203 that extends forward. Without the skirt 203, a gap between the rear end surface of the master cylinder housing and the surface 178 would be visible, which could cause an operator to misunderstand and pull the master cylinder into the servo booster assembly, misunderstanding that it was not tightened sufficiently. There is a risk of over-tightening the nut on the rod. Therefore, the skirt 203 is provided primarily to hide the gap between the master cylinder and the housing member 162 from view. The skirt 203 can also be configured to be a press fit around the outer circumference of the master cylinder flange to receive lateral loads on the master cylinder.

The rear housing member 161 is integrally provided with a rearwardly directed annular sealing lip 204 coaxially with the pull rod 166 .

Lip 204 is somewhat flexible and seals the vehicle bulkhead to prevent engine compartment fumes from bypassing the rear end of the drawbar and entering the servo booster assembly. This makes it stiff and does not require a separate gasket. In the embodiment of FIG. 11, the radial outer periphery of each of housing members 161, 162 is within a radially outward annular recess 206 formed between outwardly directed annular projections 207, 208 of housing member 162. A radially inwardly directed annular lip 205 is inserted leaving an axial gap and is a snap fit at a location indicated at 163.

The free end of lip 205 and projection 207 together form an abutment that limits axial movement of housing members 161, 162 toward each other under negative pressure. , thus limiting the clamping force that the housing member applies to bead 164. This construction of the outer periphery of the housing member allows the bead 164 to be assembled into the servo booster assembly with very little initial clamping force compared to, for example, the embodiments of FIGS. 8 and 9. .
When negative pressure is applied to one or both chambers of the servo booster assembly, the clamping force on the bead increases, but the maximum clamping force on the bead is between lip 205 and protrusion 2.
09 is engaged with. In the embodiment of FIG. 12, the pull bar 211 is connected to the rear housing member 212 of the servo booster assembly and the diaphragm support plate 2.
15 and a movable wall 214 consisting of a diaphragm 216.

The diaphragm 216 is a disk-shaped main diaphragm portion with an integrally formed rolling portion 217 for sealing the support plate 215 against the tension bar 211 and allowing the movable wall 214 to move in a direction parallel to the tension bar. 216''.The pull rod 211 has an annular recess 2 near one end.
18 is formed, and the housing member 212 has an annular recess 2
A thick annular portion 219 having a diameter of 20 is formed. A bead 225 with a rectangular cross section is provided around the inner periphery of the rolling portion 217 of the diaphragm. The radially inner portion of the bead 225 is received within the recess 218 and seals the bottom 222 of the recess 218, and the radially outer portion of the bead 225 is received within the annular recess 220 and seals the bottom 222 of the recess 218. The rear wall 225 of is sealed. Bead 221 thus seals drawbar 211 to housing member 212 and rolling portion 217 to the drawbar. Bead 221 is held by surfaces 223 and 225 so as not to move in the axial direction. The crawling portion 217 has a lip-like portion 226 extending radially outward in front of the connection between the portion 216″ of the diaphragm and the portion 217 by the thickness of the support plate 215 in order to fix the rolling portion to the support plate 215. The main diaphragm portion 216'' is integrally provided with a series of circumferentially spaced rearward facing projections 227 which act as bag stops for the movable wall. Referring to FIG. 13, drawbar 211 is sealed to housing member 212 by molding portion 219 of the housing member around the drawbar.

The diaphragm support plate 215 has a tubular portion 2 extending forward.
29 and a tubular flap portion 228 extending rearward thereof are integrally formed, both tubular portions 228, 229
It is coaxial with 1. The tubular portion 228 is provided at its rear end with a small radially outwardly directed annular projection 230 and a large radially inwardly directed annular projection 231. The servo·
An annular trough 234 coaxial and radially outwardly directed with the output and input members of the booster assembly is formed by an annular flange 232 coaxial and radially outwardly directed with the output and input members and the rear surface of the diaphragm support plate 215 . ing.

Gutter 234' surrounds the entire circumference of tubular portion 228. The diaphragm 216 has a first bead 233 provided on the radially inner periphery of the main diaphragm portion 216'' that is seated under tension within an annular gutter 234, and a rolling portion 217 that is seated under tension between the flange 232 and the protrusion 230. The second peripheral bead 235 is secured to the support plate 215 by a second peripheral bead 235 positioned in a loose web 236.
is connected to the main diaphragm portion 216' in the vicinity of the first bead 233. The loose web 236 is
The rolling portion 217 is the tubular portion 228 of the support plate 215.
allows the main diaphragm portion 216'' to seat on the support plate 215 without being affected by the seating on the support plate 215. Flexible web 23
Another bead 237 connected to the repeat 235 by 8 is formed, and the bead 237 is connected to the annular projection 231 at the rear end of the tubular section 228 of the support plate 215 and the tubular sections 228, 2.
29 and a smooth cylindrical surface 239 .

The cylindrical surface 239 has a small radial spacing from the cylindrical flexible portion of the rolling portion 217 and forms a support surface that prevents the rolling portion 217 from bulging when pressure differentials are high. The embodiment of FIG. 14 is similar to the embodiment of FIG. 13, except that in the embodiment of FIG. A flange 240 is provided. This flange 240 engages the drawbar 211 to guide the movement of the movable wall 214, preventing movement of the movable wall in a direction across the drawbar and preventing distortion of the diaphragm 216. Flange 240 and adjacent portions of tubular portion 229 are provided with a series of circumferentially spaced axial slits to form resilient fingers to reduce frictional forces between flange 240 and the drawbar. It's okay. In the embodiment of FIG. 15, the pull bar 211 is designated
It consists of first and second portions 242, 243 which are threadedly engaged with each other at points indicated at 44.

An annular recess 245 provided in the tension bar 211 is located in the bottom part 24
2, and a front surface 236 formed by the rear end surface of part 243;
3 to part 242, it is tightened between surfaces 246 and 247. At one end of recess 245, shoulder 2 of portion 242
51 engages the rear end surface of component 243 to limit axial compression of bead 248. Part 242 is permanently secured to the rear housing member 212 by molding the rear housing member 212 therearound, while part 24
3 slidably passes through the hole 249 of the front housing member 250.

Removal of drawbar component 243 allows inspection of the internal components of the servo booster assembly through hole 249.

FIG. 16 is a variation of the embodiment shown in FIG. 11, but the main difference from the embodiment of FIG. 11 is that the embodiment of FIG. , by varying the spacing of the drawbars between the front and rear threaded ends of the drawbars, as in the embodiment of FIG.

Another difference is that the sleeve 172 of the front housing member 162 is provided with circumferentially spaced, axially extending ribs 172'', which cause the rolling portion 200 of the diaphragm to engage the ribs 172'' during forward movement of the movable wall. There is something to support. The preferred number of tension bars is two, but 2
More than one pull bar may be used, or only one pull bar may be sufficient.

For example, in a coupling using a remote control valve, the two housing members may be clamped together by a single coaxial pull rod. In this case, the input member is located eccentrically from the axis of the servo booster assembly. The drawbar can be formed as a molded boss on one or both of the two housing members.

The present invention is also applicable to vacuum servo booster assemblies of the type in which both chambers of the housing are at atmospheric pressure when inactive.

In that case, in the inactive state there is atmospheric pressure in front and behind the movable wall, and the poppet valve device introduces negative pressure into the front chamber when the valve actuation rod is actuated. Again, in the inactive state the external forces are balanced, and in the active state atmospheric pressure forces the two housing members together. Almost the same structure can be applied to the compressed air servo booster assembly with only slight modifications.

In this case, it is necessary to tighten the two housing members around each other so as to withstand the internal air pressure. Still, the entire compressed air servo booster assembly can be lighter than conventional construction. The reason for this is that the housing member can be thinner than conventional, is allowed to expand (i.e. bulge) slightly due to internal air pressure, and axial distortion and therefore movement from the force transmitting hand. The present invention is readily applicable to non-cylindrical servo booster assemblies.

Servo booster assemblies that are oval, square or rectangular in cross section are susceptible to twisting of the movable wall in the gap between the housing member, resulting in wear and torsional stress on the flexible diaphragm, and failure. By providing the aforementioned tension rods, such twisting can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a servo booster assembly according to an embodiment of the present invention, taken along line A--A in FIG. , FIG. 2 is a front view of the servo booster assembly of FIG. 1, FIG. 3 is a view showing a modification of the pull rod, FIGS. 4 and 5 are detailed views of another modification, and FIG. Figure 7 shows an embodiment in which the tension rod has a bent end; Figure 7 shows an embodiment in which the tension rod is provided with a shoulder located in front of the front wall of the booster housing; Figure 8 shows the housing. FIG. 9 is the same as that shown in FIG. 8, showing an embodiment in which the member is provided with a sleeve coaxial with the drawbar and the diaphragm is sealed into one sleeve by a rolling part integral with the main diaphragm part; Figure 10 shows an example of the use of a welding tool to determine the spacing between the front housing member and the rear housing member in a construction similar to Figure 10, in which the front housing member is secured to each tension bar by deforming its insert. FIG. 11 shows a construction in which the inner peripheral bead of the rolling section, which is integral with the main diaphragm section, is held by the ends of two opposing sleeves through which tension rods pass, and the outer peripheral bead of the main diaphragm section is Figure 12 shows a structure with a tightening device for
Figures 13 and 14 show an embodiment in which the rolling portion of the diaphragm is sealed to the rear housing member by an inner circumferential beam of the rolling portion of the diaphragm sealing the movable wall to the pull rod; FIGS. FIG. 15 shows an embodiment in which the peripheral bead of the rolling portion of the diaphragm is placed in a recess formed between two mutually threaded parts of the tension rod; FIG. 12 shows a variation of the embodiment of FIG. 11 using a bent drawbar; FIG. 10...Housing, 12,161,212.
...One housing wall, 14,162,250
・・・・・・Other housing wall, 100, 130, 1
66,211...force transmission member, 116,147
, 174... Master cylinder connecting member, 118
, 120, 122, 173... Vehicle bulkhead connection member.

Claims (1)

Claims: 1. A servo-booster assembly for a vehicle brake system for use with a master cylinder, comprising: a booster housing having opposed first and second housing walls; a master cylinder coupling member provided on the first housing wall for coupling to the master cylinder housing; and a master cylinder coupling member provided on the first housing wall for coupling to the master cylinder housing;
a vehicle bulkhead connection member provided on the second housing wall for connecting the housing wall to the vehicle bulkhead; and a movable wall disposed between the housing walls and dividing the interior of the booster housing into two chambers. a vehicle brake having 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. In the system servo booster assembly,
at least one fixed force transmission member 100; 130 for transmitting axial force through said booster housing;
;166;211 is the first housing wall 12;1;
61; 212 through the movable wall to the second housing wall 14; 162; 250, the movable wall being directly or indirectly sealed to the force transmitting member;
a first end of the force transmitting member is located adjacent to the master cylinder coupling member 116; 147; 174;
and the first housing is rigidly connected to the master cylinder connecting member so that braking reaction force is directly transmitted from the housing of the master cylinder to the force transmitting member, so that when the servo booster assembly is operated, the first housing at least a majority of the wall is adapted to be immune to the braking reaction force, the second end of the force transmitting member is located adjacent to the vehicle bulkhead connection member 118; 120; 122; 173, and rigidly connected to the vehicle bulkhead connecting member;
A braking reaction force is transmitted directly from the vehicle bulkhead to the force transmitting member such that at least a majority of the second housing wall is not subject to the braking reaction force during operation of the servo-booster assembly. A servo booster assembly characterized by: 2. In the servo booster assembly of claim 1, it is provided that at least a majority of said housing walls are of such thickness and material that they are significantly deformed in the axial direction by said braking reaction force. Features a servo booster assembly. 3. The servo booster assembly of claim 1 or 2, wherein at least one of the rigid connections between said connecting member and a corresponding end of said force transmitting member is provided in said housing wall. A servo booster assembly characterized in that the connecting member and the ends of the force transmitting member are each independently connected to a locally reinforced small portion. 4. A servo booster assembly as claimed in any one of claims 1 to 3, wherein the force transmitting member is a drawbar. 5. The servo booster assembly of claim 4 having only one pull rod as said force transmitting member. 6. The servo booster assembly of claim 4, wherein each drawbar is laterally offset from the movable wall center axis. 7. The servo booster assembly of claim 6, wherein a plurality of pull rods are circumferentially spaced from each other at equal intervals about the central axis. 8. The servo booster assembly of claim 7, wherein only two drawbars are arranged symmetrically with respect to the central axis. 9 Any one of claims 4 to 8
In the servo-booster assembly of paragraph 1, at least one end of each of the drawbars is directly connected to the corresponding coupling member, so that the housing wall can absorb the braking reaction force during operation of the servo-booster assembly. A servo booster assembly characterized in that it is completely unaffected by. 10. Claim 9, wherein said one end of said drawbar projects outwardly through said corresponding housing wall.
Servo booster assembly. 11. The servo booster assembly of claim 10, wherein each end of said drawbar projects through a respective housing wall. 12. A servo booster assembly as claimed in claim 10 or claim 11, wherein each said protruding end of the draw rod has a thread to form said connecting member. 13. The servo booster assembly of any one of claims 10 to 12, wherein each end of the draw rod passing through a corresponding housing wall is press-fitted into a hole in the housing wall. A servo featuring
booster assembly. 14 The hole is stepped and the step of the hole corresponds to 1 of the tension rod.
14. The servo booster assembly of claim 13, wherein the servo booster assembly cooperates with an outwardly directed abutment at the end to limit inward movement of the housing wall relative to the end of the drawbar. 15. Servo booster according to any one of claims 9 to 14, wherein the drawbar has a bent section, the ends of the drawbar being laterally offset relative to each other. assembly. 16. A servo booster assembly according to any one of claims 1 to 15, wherein the housing wall is made of plastic material. 17. In the servo booster assembly according to any one of claims 1 to 16, the master cylinder connecting member is fixed to the housing of the master cylinder, and the vehicle bulkhead connecting member is fixed to the bulkhead of the vehicle. A servo booster assembly characterized in that it is fixed.