GB2074270A - Servo valves for brake boosters - Google Patents

Servo valves for brake boosters Download PDF

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Publication number
GB2074270A
GB2074270A GB8110171A GB8110171A GB2074270A GB 2074270 A GB2074270 A GB 2074270A GB 8110171 A GB8110171 A GB 8110171A GB 8110171 A GB8110171 A GB 8110171A GB 2074270 A GB2074270 A GB 2074270A
Authority
GB
United Kingdom
Prior art keywords
valve
abutment
collar
face
control member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8110171A
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GB2074270B (en
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ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Priority to GB8110171A priority Critical patent/GB2074270B/en
Publication of GB2074270A publication Critical patent/GB2074270A/en
Application granted granted Critical
Publication of GB2074270B publication Critical patent/GB2074270B/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/24—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being gaseous
    • B60T13/46—Vacuum systems
    • B60T13/52—Vacuum systems indirect, i.e. vacuum booster units
    • B60T13/57—Vacuum systems indirect, i.e. vacuum booster units characterised by constructional features of control valves

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Braking Systems And Boosters (AREA)

Abstract

A conventional vacuum booster has a valve control member (1) reciprocable in a bore of a valve body (4) and engageable at its front end with a resilient reaction disc (5), the valve control member (1) being provided at its rear end with a first annular valve seat (10) that is coaxial with a second annular valve seat (11) provided on the valve body (4), and a valve member (13) engageable with the valve seats (10, 11). The axial spacing (x) between the front face of the valve control member (1) and a support surface for the rear face of the reaction disc is set by a method having the steps of, before assembly of the reaction disc and valve member to the valve body (4), locating a first cylindrical abutment member (16) provided with an axial spigot (17) adjacent to the front face of the valve control member (1), bringing a second abutment member, in the form of a cylindrical ultrasonic welding probe (18) having a plane end face (19), upwardly into engagement with the lower most valve seat (10 or 11), and plastically deforming that valve seat until both valve seats (10, 11) are coplanar. The clearance (x) is thereby made equal to the axial length of the spigot. <IMAGE>

Description

SPECIFICATION Servo valves for brake boosters The invention relates to a method of adjusting the clearance between part of a resilient reaction disc and a valve control member in a servo booster for a vehicle braking system, and is particularly concerned with effecting this adjustment in a booster of the kind comprising a valve body provided with a stepped bore, a valve control member reciprocable in said bore and engageable at its front end with a resilient reaction disc through which output forces are transmitted to an output member, the valve control member being provided at its rear end with a first annular valve seat that is coaxial with a second annular valve seat provided on the valve body, a valve member engageable with the valve seats, and an input rod connected to the valve control member.Such a booster will hereinafter be referred to as a 'booster of the kind set forth'.
In boosters of the kind set forth it is important to control the various dimensions such that in the condition in which both valve seats are lapped by the valve member there is a predetermined axial spacing between the front end face of the control valve member and a support surface for the radially outer portion of the rear face of the reaction disc. The size of this spacing determines the amount by which the booster output force must rise before a substantial reaction is applied by the reaction disc to the control valve member.
The effect of this to increase the boost ratio during the take-up of this spacing or clearance to provide a 'jump-in' for overcoming stiction.
Since the clearance is determined by several dimensions it is normally necessary to control tolerances in each of those dimensions to a high degree which increases the manufacturing costs.
According to the invention a method of setting the axial spacing between the front face of the valve control member and a support surface for the radially outer portion of the rear face of the reaction disc in a booster of the kind set forth comprises, before assembly of the reaction disc and valve member to the valve body, locating a first abutment member adjacent to the front face of the valve control member, and locating a second abutment member adjacent to the valve seats, the first abutment member having a first abutment surface adapted for engagement with the front face of the valve control member and a second abutment surface adapted for engagement with said support surface, and the second abutment member having a third abutment surface for engagement with the first valve seat and a fourth abutment surface for engagement with the second valve seat, moving the first and second abutment members relatively together and permanently displacing at least one part of the valve assembly so that on completion of the movement all four abutment surfaces engage with their corresponding members, the relative axial positions of the first and second abutment surfaces and those of the third and fourth abutment surfaces being chosen such that in the assembled condition the desired axial spacing will have been predetermined by said displacement of said one valve part.
The permanent displacement of said valve part is preferably achieved by plastically deforming that part.
When plastic deformation is utilised this is preferably accomplished by ultra-sonic means, which conveniently comprises an ultra-sonic vibrator for one of the abutment members.
However, the deformation could be performed in other ways by the use of a heating coil for example.
Preferably the second abutment member is provided with a plain face which constitutes both said third and fourth abutment surfaces, and the first abutment member is formed with an annular second abutment surface, and with a coaxial projecting spigot of which the end face constitutes the first abutment surface. The length of the spigot determines said axial spacing in the assembled booster.
The support surface will usually be provided on a plastics collar which encircles the front end of the valve control member, and preferably the collar is the part that is plastically deformed, the axial length of the collar being reduced by the plastic deformation.
Either the collar or the adjacent part of the valve body is preferably then provided initially with at least one recess to receive the material displaced during the plastic deformation of the collar.
Instead of, or in addition to, deformation of a collar, at least one of the valve seats may be deformed by the second abutment member. When only one of the seats is intended to be deformed that seat is arranged initially to project axially rearwardly beyond the other prior to deformation.
The invention will now be further described, by way of exampie only, with reference to the accompanying schematic drawings in which: FIGURE 1 is a longitudinal cross-section of a part of a conventional brake servo booster showing the arrangement of the reaction disc and valve control member, the valve control member being shown in the position in which both valve seats are lapped; FIGURE 2 is a similar view showing application of an ultra-sonic probe to deform one of the valve seats by a first method in accordance with the invention; FIGURE 3 illustrates the use of a second method in accordance with the invention by which the collar of the assembly of Figure 1 is deformed; and FIGURE 4 illustrates a modified method in accordance with the invention for deforming the collar.
With reference to Figure 1 a cylindrical valve control member 1 is slidably guided in a reduced diameter portion 2 of a stepped bore 3 of a moulded plastics valve body 4. An elastomeric reaction disc 5 abuts at its front end a head 6 on an output rod 7, and an annular portion 8 of its rear face abuts the front face 9' of a valve body collar 9. Front face 9' constitutes a support surface for the reaction disc 5. In the lapped condition shown coaxial first and second valve seats 10 and 11 respectively on the rear end of the valve control member 1 and on the valve body 4 respectively are both engaged by a plain annular face 12 on a valve member 13. The clearance X between the radially outer part of the front surface 1 4 of the valve control member and the adjacent surface 1 5 of the reaction disc is set by the method of the invention.ClearanceX also represents the axial spacing between front face 9' of collar 9 and the front surface 14 of the valve control member.
With reference to Figure 2 a first cylindrical abutment member 16 is provided with a shallow axial spigot 1 7 of length equal to the desired clearance X and the member 1 6 is brought so that its annular surface 20, the second abutment surface, abuts the front face 9' of the collar 9.
A second abutment member in the form of an ultra-sonic welding probe 1 8 of cylindrical shape with a plain end face 1 9 is brought upwardly so that its end face 19 engages with whichever of the valve seats is iowermost, and deforms that valve seat until both valve seats 10, 11 are co-planar, with the upper face of the valve control member in engagement with the end face 21, the first abutment surface, of the spigot 1 7. The clearance X has then been determined for the lapped condition of the assembled booster. It will be appreciated that in this case the plain face 1 9 constitutes both the third and fourth abutment surfaces.
Of course, the first abutment member 1 6 could be provided with a plain end face, and the second abutment member could be provided with a spigoted end face, or both abutment members could be provided with spigoted end faces, provided that whichever configuration is adopted the axial spacing between the first and third abutment surfaces differs by the desired value X from the axial spacing between the second and fourth abutment surfaces.
With reference to Figure 3, the valve assembly in this case is substantially the same as that shown in Figures 1 and 2, except that the valve body 4 has been provided with an annular recess 22 confronting the radially outer wall 23 of the collar 9. The method in this case comprises ultrasonically vibrating the first abutment member t6 whilst the members 16 and 18 are moved relatively together, with the result that the plastics collar 9 is plastically deformed to reduce its length until the desired spacing X has been achieved.
Recess 22 accommodates material plastically displaced during the reduction in the length of the collar 9.
With reference to Figure 4, in the case the rear end of the collar 9 is provided with a series of circumferentially spaced, radially extending slots 24 so that ultrasonic deformation of the material of the collar between the slots can take place to allow the axial length of the collar to be reduced, again by ultrasonic vibration of the abutment member 1 6.
In yet another method of setting the clearance X the collar 9 is arranged initially to be a tight fit but capable of a limited amount of axial movement rearwardly relative to the valve body 4, that is downwardly in Figures 3 and 4. The fit may be sufficiently tight to maintain the collar 9 in the adjusted position after the member 1 6 and 1 8 have been moved relatively together to apply a predetermined force, or auxiliary means may be provided to lock the collar in the adjusted postion.
The auxiliary means may be an adhesive bond.

Claims (19)

1. A method of setting the axial spacing between the front face of the valve control member and a support surface for the radially outer portion of the rear face of the reaction disc in a booster of the kind set forth comprising, before assembly of the reaction disc and valve mamber to the valve body, locating a first abutment member adjacent to the front face of the valve control member, and locating a second abutment member adjacent to the valve seats, the first abutment member having a first abutment surface adapted for ,engagement with the front face of the valve control member and a second abutment surface adapted for engagement with said support surface, and the second abutment member having a third abutment surface for engagement with the first valve seat and a fourth abutment surface for engagement with the second valve seat, moving the first and second abutment members relatively together and permanently displacing at least one part of the valve assembly so that on completion of the movement all four abutment surfaces engage with their corresponding members, the relative axial positions of the first and second abutment surfaces and those of the third and fourth abutment surfaces being chosen such that in the assembled condition the desired axial spacing will have been predetermined by said displacement of said one valve part.
2. A method as claimed in Claim 1, in which the permanent displacement of said one valve part is produced by plastically deforming that part.
3. A method as claimed in Claim 2, in which ultrasonic means are used to plastically deform said valve part.
4. A method as claimed in Claim 3, in which at least one of the abutment members comprises an ultra-sonic vibrator.
5. A method as claimed in Claim 2, in which said valve part is plastically deformed by heating.
6. A method as claimed in any preceding claim, in which at least one of the abutment members is provided with a spigot projecting axially from an end face of said one abutment member, the end faces of said abutment member and of the spigot constituting a respective pair of said abutment surfaces.
7. A method as claimed in Claim 6, in which the second abutment member is provided with a plain face which constitutes both said third and fourth abutment surfaces, and the spigot projects from the end face of the first abutment member by an amount equal to said axial spacing, the end face of the spigot constituting the first abutment surface and the end face of the first abutment member constituting the second abutment surface.
8. A method as claimed in any one of Claims 2 to 7, in which the support surface is provided on a collar which encircles the front end of the valve control member.
9. A method as claimed in Claim 8, in which the collar constitutes the valve part that is plastically deformable, the axial length of the collar being reduced upon plastic deformation.
10. A method as claimed in Claim 9, in which at least one recess is initially provided in the collar or in the adjacent part of the valve body to receive the material displaced during the plastic deformation of the collar.
1 A method as claimed in Claim 10, in which the recess comprises an annular recess in the radially inner wall of the valve body.
12. A method as claimed in Claim 10, in which the rear end of the collar is provided with radially extending slots which allow reduction of the axial length of the collar by means of plastic deformation of the material of the collar between the slots.
13. A method as claimed in Claim 9, in-which the collar is arranged initially to be a tight fit, but capable of a limited amount of axial movement rearwardly relative to the valve body, -the tightness of the fit after such movement being sufficient to maintain the collar in the adjusted postion in use.
14. A method as claimed in Claim 9, in which the collar is initially capable of a limited amount of axial movement rearwardly relative to the valve body, and auxiliary means are provided to lock the collar in the adjusted position in use.
1 5. A method as claimed in any one of Claims 1 to 9, in which at least one of the valve seats constitutes said one valve part which is permanently displaced.
16. A method as claimed in Claim 1 5 as appended to Claim 7, in which one of the valve seats initially projects axially rearwardly beyond the other valve seat, the second abutment member being moved relatively towards the first abutment member so that said one valve seat is permanently displaced until both of the valve seats are co-planar.
1 7. A method of setting the axial spacing between the front face of the valve control member and a support surface for the radially outer portion of the rear face of the reaction disc in a booster of the kind set forth substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.
18. A method of setting the axial spacing between the front face of the valve control member and a support surface for the radially outer portion of the rear face of the reaction disc in a booster of the kind set forth substantially as herein described with reference to Figures 1 and 3 of the accompanying drawings.
19. A method as claimed in Claim 18, but modified substantially as herein described with reference to Figure 4 of the accompanying drawings.
GB8110171A 1980-04-16 1981-04-01 Servo valves for brake boosters Expired GB2074270B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8110171A GB2074270B (en) 1980-04-16 1981-04-01 Servo valves for brake boosters

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8012566 1980-04-16
GB8110171A GB2074270B (en) 1980-04-16 1981-04-01 Servo valves for brake boosters

Publications (2)

Publication Number Publication Date
GB2074270A true GB2074270A (en) 1981-10-28
GB2074270B GB2074270B (en) 1984-03-14

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4474103A (en) * 1981-10-01 1984-10-02 Automotive Products Plc Brake boosters
DE3318744A1 (en) * 1983-05-24 1984-11-29 Alfred Teves Gmbh, 6000 Frankfurt Vacuum-operated brake booster
FR2560134A1 (en) * 1984-02-23 1985-08-30 Teves Gmbh Alfred BRAKING EFFORT AMPLIFIER WITH LOW PRESSURE
GB2157378A (en) * 1984-02-29 1985-10-23 Teves Gmbh Alfred Vacuum-operated power brake booster
FR2582274A1 (en) * 1985-05-24 1986-11-28 Teves Gmbh Alfred PRESSURE BRAKE AMPLIFIER
EP0469937A1 (en) * 1990-07-31 1992-02-05 Alliedsignal Europe Services Techniques Threshold valve adjusting method for a pneumatic brake booster and servomotor to carry out this method
US5146837A (en) * 1990-11-22 1992-09-15 Jidosha Kiki Co., Ltd. Reaction transmitting mechanism of brake booster
US5261313A (en) * 1992-07-24 1993-11-16 Allied-Signal Inc. Plunger for a control valve with variable reaction force
US5425302A (en) * 1992-05-26 1995-06-20 Bendix Europe Services Techniques Pneumatic booster
DE19545947A1 (en) * 1995-12-08 1997-06-12 Lucas Ind Plc Brake booster and assembly method therefor
FR2809067A1 (en) * 2000-05-22 2001-11-23 Bosch Sist De Frenado Sl Servomotor for motor vehicle brakes has adjuster between front and rear faces of sensor which can be plastically
FR2855135A1 (en) * 2003-05-22 2004-11-26 Bosch Gmbh Robert Pneumatic servomotor for vehicle, has sensor immobilized between reaction plate and shroud, where predetermined gap separates front end of fitment from back end of sensor, in resting or non-braking position

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4474103A (en) * 1981-10-01 1984-10-02 Automotive Products Plc Brake boosters
DE3318744A1 (en) * 1983-05-24 1984-11-29 Alfred Teves Gmbh, 6000 Frankfurt Vacuum-operated brake booster
FR2560134A1 (en) * 1984-02-23 1985-08-30 Teves Gmbh Alfred BRAKING EFFORT AMPLIFIER WITH LOW PRESSURE
US4643075A (en) * 1984-02-23 1987-02-17 Itt Industries, Inc. Vacuum-operated brake power booster
GB2157378A (en) * 1984-02-29 1985-10-23 Teves Gmbh Alfred Vacuum-operated power brake booster
FR2582274A1 (en) * 1985-05-24 1986-11-28 Teves Gmbh Alfred PRESSURE BRAKE AMPLIFIER
GB2175659A (en) * 1985-05-24 1986-12-03 Teves Gmbh Alfred Vacuum-operated brake power booster
US5167180A (en) * 1990-07-31 1992-12-01 Bendix Europe Services Techniques Process for adjusting the value of the jump of a pneumatic brake-booster and booster for carrying out this process
FR2665409A1 (en) * 1990-07-31 1992-02-07 Bendix Europ Services Tech METHOD OF ADJUSTING THE JUMP VALUE OF A PNEUMATIC BRAKE ASSIST SERVOMOTOR AND SERVOMOTOR FOR IMPLEMENTING SAID METHOD.
EP0469937A1 (en) * 1990-07-31 1992-02-05 Alliedsignal Europe Services Techniques Threshold valve adjusting method for a pneumatic brake booster and servomotor to carry out this method
US5146837A (en) * 1990-11-22 1992-09-15 Jidosha Kiki Co., Ltd. Reaction transmitting mechanism of brake booster
US5425302A (en) * 1992-05-26 1995-06-20 Bendix Europe Services Techniques Pneumatic booster
US5261313A (en) * 1992-07-24 1993-11-16 Allied-Signal Inc. Plunger for a control valve with variable reaction force
DE19545947A1 (en) * 1995-12-08 1997-06-12 Lucas Ind Plc Brake booster and assembly method therefor
US6092453A (en) * 1995-12-08 2000-07-25 Lucas Industries Public Limited Company Brake servo unit and method assembling said unit
DE19545947C2 (en) * 1995-12-08 2002-08-22 Lucas Ind Plc Brake booster and assembly method therefor
FR2809067A1 (en) * 2000-05-22 2001-11-23 Bosch Sist De Frenado Sl Servomotor for motor vehicle brakes has adjuster between front and rear faces of sensor which can be plastically
WO2001089901A1 (en) * 2000-05-22 2001-11-29 Bosch Sistemas De Frenado, S.L. Brake servo unit comprising a bushing adjustable by deformation, and assembly for adjusting the bushing
AU774150B2 (en) * 2000-05-22 2004-06-17 Bosch Sistemas De Frenado, S.L. Brake servo unit comprising a bushing adjustable by deformation, and assembly for adjusting the bushing
FR2855135A1 (en) * 2003-05-22 2004-11-26 Bosch Gmbh Robert Pneumatic servomotor for vehicle, has sensor immobilized between reaction plate and shroud, where predetermined gap separates front end of fitment from back end of sensor, in resting or non-braking position

Also Published As

Publication number Publication date
GB2074270B (en) 1984-03-14

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PCNP Patent ceased through non-payment of renewal fee