GB2258893A - Deceleration sensitive proportioning valve - Google Patents
Deceleration sensitive proportioning valve Download PDFInfo
- Publication number
- GB2258893A GB2258893A GB9117850A GB9117850A GB2258893A GB 2258893 A GB2258893 A GB 2258893A GB 9117850 A GB9117850 A GB 9117850A GB 9117850 A GB9117850 A GB 9117850A GB 2258893 A GB2258893 A GB 2258893A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bore
- deceleration
- valve
- stepped bore
- sensitive
- 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.)
- Withdrawn
Links
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
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/26—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels
- B60T8/28—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels responsive to deceleration
- B60T8/285—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels responsive to deceleration using horizontal moving mass
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Hydraulic Control Valves For Brake Systems (AREA)
Abstract
A deceleration sensitive proportioning valve (10) comprises a housing (12); an inertia sensitive member (18); a primary piston (14) downstream of the inertia sensitive member and carrying a valve member (20) engageable with the inertia sensitive member; a stepped control piston (16) slidably mounted in a stepped bore (70) in the primary piston; a primary spring (74) biasing the control piston towards the outlet and against a stop member (72); and resilient thrust means (88, 90) which exert a biasing force on the inertia sensitive member normally to space the inertia sensitive member from the valve seat. For an unladen vehicle the member (18) closes the valve (20) at a first cut in pressure and when the inlet pressure reaches a higher predetermined level the primary piston (14) moves to increase the outlet pressure in the usual way. For an laden vehicle deceleration is insufficient to close the valve until a second, higher, cut in pressure is reached. In the meantime the increasing pressure acting on the different cross-sectional areas of the control piston (16) displace it against the spring (74) to increase the bias applied by the means (88, 90) to keep the member (18) away from the valve (20). <IMAGE>
Description
DECELERATION SENSITIVE PROPORTIONING VALVE
This invention relates to a deceleration sensitive proportioning valve of the type used for regulating the pressure of the hydraulic fluid in a braking system of a motor vehicle.
A deceleration sensitive proportioning valve is positioned between a source of fluid pressure (for example, a master cylinder) of the braking system and a brake cylinder at a wheel of the motor vehicle.
The deceleration sensitive proportioning valve acts to limit or restrict the fluid pressure applied to the brake cylinder to reduce the risk of wheel lock on braking. In usual circumstances, a deceleration sensitive proportioning valve is positioned between the master cylinder and the rear wheel brake cylinders.
Various designs of deceleration sensitive proportioning valves are known, as, for example, disclosed in GB Patent No. 1563171. These known arrangements include an inertia sensitive member (usually a ball) engageable with a valve seat to restrict the flow of hydraulic fluid between the inlet and outlet of the deceleration sensitive proportioning valve. Typically, the housing of the deceleration sensitive proportioning valve is secured to the motor vehicle at an angle to the horizontal such that the outlet is above the inlet relative to the horizontal, with the outlet nearer the front of the motor vehicle. Movement of the inertia sensitive member relative to the valve seat takes place when the deceleration of the motor vehicle exceeds a fixed predetermined value. Such movement causes the inertia sensitive member to engage the valve seat to close off the inlet from the outlet.The fluid pressure at the inlet, when the valve closes, is known as the cut-in pressure. As the motor vehicle load increases, then the fluid pressure at the inlet must also increase to generate a deceleration at the predetermined level. Consequently, the value of the cut-in pressure varies dependent on the load on the motor vehicle. For vehicle decelerations below the predetermined value, fluid flow between the inlet and outlet is unrestricted.
These known deceleration sensitive proportioning valves have the disadvantage that the cut-in pressure for laden and unladen motor vehicles is actuated at the same predetermined value of deceleration. For a laden motor vehicle, this can result in "premature" closure of the deceleration sensitive proportioning valve, that is, a cut-in pressure well below the ideal value. It is the object of the present invention to overcome this disadvantage.
To this end, a deceleration sensitive proportioning valve in accordance with the present invention comprises a housing having a stepped bore means therethrough with an inlet and an outlet; an inertia sensitive member slidably mounted in the stepped bore means adjacent the inlet; a primary piston mounted in the stepped bore means between the inertia sensitive member and the outlet and normally spaced from the inertia sensitive member, the primary piston having a stepped bore therethrough; a valve member positioned in the end of the primary piston directed towards the inertia sensitive member, the valve member being substantially annular and having a central aperture opening into the stepped bore in the primary piston and defining a valve seat engageable with the inertia sensitive member; a control piston slidably mounted in the stepped bore in the primary piston, the control piston having a bore therethrough and having a first diameter portion directed towards the outlet and a second diameter portion directed towards the inertia sensitive member, the first diameter portion having a larger diameter than the second diameter portion; a primary spring positioned in the stepped bore in the primary piston and biasing the control piston towards the outlet and against a stop member secured in the stepped bore; resilient thrust means partially positioned in the bore in the control piston and extending through the central aperture in the valve member to engage the inertia sensitive member, the resilient thrust means comprising a secondary spring engaging a shoulder in the bore in the control piston to exert a biasing force on the inertia sensitive member to normally space the inertia sensitive member from the valve seat.
In this arrangement, as braking occurs, the inlet pressure increases causing the motor vehicle to decelerate. If the deceleration exceeds a predetermined level, the inertia sensitive member moves against the bias of the secondary spring to engage the valve seat and close the deceleration sensitive proportioning valve. For a laden motor vehicle (in comparison to an unladen motor vehicle) a higher inlet pressure is required to produce the same level of deceleration. In the present invention this increased inlet pressure causes the control piston to move towards the inertia sensitive member to compress the secondary spring, thereby increasing the biasing force exerted by the secondary spring on the inertia sensitive member. As a result, for laden motor vehicles, an even higher level of deceleration is required to bring the inertia sensitive member into engagement with the valve seat.
Preferably, the resilient thrust means further comprises a thrust member positioned between, and in engagement with, the secondary spring and the inertia sensitive member. In this case, the thrust member preferably comprises an elongate body having outwardly directed, longitudinally extending, ribs which are substantially equidistantly spaced apart to define flutes therebetween.
The primary piston is preferably slidably mounted in the stepped bore means for limited movement towards and away from the outlet, the primary piston having a first diameter portion directed towards the inertia sensitive member and a second diameter portion directed towards the outlet, the first diameter portion having a smaller diameter than the second diameter portion.
A plate member is preferably fixedly positioned in the stepped bore means between the inertia sensitive member and the inlet to limit the travel of the inertia sensitive member towards the inlet.
Preferably, the stop member comprises a circlip fixedly secured in a groove in the stepped bore in the primary piston.
The housing preferably comprises a body member having a bore therethrough; an end cap screw-threaded into an open end of the bore in the body member, the end cap having a bore therethrough; and a cylindrical sleeve secured in the bore in the body member between the end cap and a shoulder in the bore in the body member, the cylindrical sleeve having a stepped bore therethrough, the bores in the body member and the end cap and the stepped bore in the cylindrical sleeve defining the stepped bore means, the inertia sensitive member being positioned in the stepped bore in the cylindrical sleeve. Preferably, in this case, the bore in the body member defines the outlet and the bore in the end cap defines the inlet.
Preferably, the inertia sensitive member is a ball.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a cross-sectional view of a deceleration sensitive proportioning valve in accordance with the present invention in its normal position;
Figure 2 is a side view of the thrust member of the deceleration sensitive proportioning valve of
Figure 1;
Figure 3 is an end view of the thrust member of
Figure 2; and
Figure 4 is a graph of inlet pressure against outlet pressure for the variou stages of operation of the deceleration sensitive proportioning valve of
Figure 1.
A deceleration sensitive proportioning valve 10 is shown in Figure 1 which comprises a housing 12, a primary piston 14, a control piston 16, an inertia sensitive member in the form of a ball 18, and a valve member 20. The housing 12 comprises a body member 22 which has a bore 24 therethrough which, at one end, defines an outlet 26 for the deceleration sensitive proportioning valve 10; and an end cap 28 which is screw threaded into the other end of the bore and which has also has a bore 30 therethrough which defines an inlet 32 for the deceleration sensitive proportioning valve. A cylindrical sleeve 34 is fixedly positioned in the bore 24 of the body member 22 between the end cap 28 and a first shoulder 36 in the bore 24. The cylindrical sleeve 34 has a stepped bore 38 comprising a first portion 40 having a larger diameter than a second portion 42.The ball 18 is positioned in the first portion 40 of the stepped bore 38 and is movable relative to the cylindrical sleeve 34. A plate member 44 is fixedly positioned between the cylindrical sleeve 34 and the end cap 28 to retain the ball 18 in the first portion 40. The plate member 44 has apertures 46 therethrough to allow free passage of hydraulic fluid. A seal 48 is fixedly secured between the cylindrical sleeve 34, the end cap 28, and the plate member 44 to substantially prevent leakage of hydraulic fluid. The bores 24,30 and stepped bore 38 define stepped bore means for the housing 12.
The primary piston 14 is slidably positioned in the bore 24 between the outlet 26 and the ball 18.
The primary piston 14 is substantially cylindrical and has an outer surface 50 comprising a first portion 52 which makes a sliding fit in the second portion 42 of the stepped bore 38 of the cylindrical sleeve 34; and a second portion 54 which makes a sliding fit in a portion 56 of the bore 24 in the body member 22. The first portion 52 of the outer surface 50 defines a first diameter portion of the primary piston 14, and similarly, the second portion 54 defines a second diameter portion of the primary piston. The first diameter portion is directed towards (relative to the second diameter portion) the ball 18, and the second diameter portion is directed towards (relative to the first diameter portion) the outlet 26. The second diameter portion of the primary piston 14 has a larger diameter than the first diameter portion thereof.A shoulder 58 is formed between the first and second portions 52,54 which is engageable with an end face 60 of the cylindrical sleeve 34. Seals 62,64 are positioned between the first portion 52 of the outer surface 50 and the second portion 42 of the stepped bore 38, and between the second portion 54 of the outer surface 50 and the portion 56 of the bore 24, respectively to substantially prevent leakage of hydraulic fluid.
The valve member 20 is secured to the end of the primary piston 14 directed towards the ball 18 by a retainer 66. The valve member 20 is substantially annular and has a central aperture 67 therethrough which defines a valve seat 68 engageable with the ball 18 to close the deceleration sensitive proportioning valve 10. The other end of the primary piston 14 is directed towards a thrust washer 102 which is positioned in the bore 24 between a second shoulder 104 in the bore 24 and the primary piston.
The sliding movement of the primary piston 14 relative to the housing 12 is therefore limited by the end face 60 and the second shoulder 104.
The primary piston 14 has a stepped bore 70 therethrough. The control piston 16 is slidably mounted in the stepped bore 70 and is biased towards the outlet 26, and into contact with a stop member 72 in the stepped bore 70, by a primary spring 74. The stop member 72 is defined by a circlip positioned in a groove in the stepped bore 70. The primary spring 74 is positioned between a first shoulder 76 on the outer surface 78 of the control piston 16 and a shoulder 80 in the stepped bore 70. The outer surface 78 of the control piston 16 comprises first, second and third portions 110,108,106 respectively.
The first portion 110 of the outer surface 78 defines a first diameter portion of the control piston 16, and similarly, the second portion 108 defines a second diameter portion of the control piston, and the third portion 106 defines a third diameter portion of the control piston. The first diameter portion is directed towards (relative to the second diameter portion) the outlet 26, and the second diameter portion is directed towards (relative to the first diameter portion) the ball 18. The third diameter portion of the control piston 16 has a smaller diameter than the second diameter portion thereof, which in turn has a smaller diameter than at the first diameter portion thereof. The first shoulder 76 is defined by the step between the third and second portions 106,108 respectively.A second shoulder 77 is defined by the step between the second and first portions 108,110 respectively. The second and first portions 108,110 respectively make a sliding fit with corresponding portions of the stepped bore 70 in the primary piston 14. Seals 82,84 are positioned between the second and first portions 108,110 respectively of the outer surface 78 of the control piston 16 and the corresponding portions of the stepped bore 70 in the primary piston 14. The seals 82,84 hydraulically isolate the second and first portions 108,110 respectively.
A bore 86 extends through the control piston 16 and has positioned therein resilient thrust means comprising a thrust member 88 and a secondary spring 90. The thrust member 88 extends out of the bore 86 in the control piston 16, through part of the stepped bore 70 in the primary piston 14, and through the central aperture 67 in the valve member 20. The secondary spring 90 engages a shoulder 92 in the bore 86 of the control piston 16 and one end 94 of the thrust member 88 to bias the other end 96 of the thrust member into contact with the ball 18, and thereby normally bias the ball 18 into contact with the plate member 44 and away from the valve seat 68.
The thrust member 88 (Figures 2 and 3) comprises an elongate body 98 with three outwardly directed, longitudinally extending, ribs 100 which are substantially equidistantly spaced apart. The gaps or flutes between the ribs 100 allow free flow of hydraulic fluid.
The various bores 24,30,38,70,86 and the central aperture 67 have longitudinal axes which are aligned with one another, and with the longitudinal axis A of the deceleration sensitive proportioning valve 10. In use, the deceleration sensitive proportioning valve 10 may be mounted in any suitable position with the longitudinal axis A substantially parallel to the longitudinal axis of the motor vehicle. Preferably, however, the deceleration sensitive proportioning valve 10 is mounted substantially horizontal, with the outlet nearer the front of the motor vehicle.
The operation of the deceleration sensitive proportioning valve 10 will now be described, with reference to Figure 4. Figure 4 shows the ideal curves for inlet pressure against outlet pressure for a laden and an unladen motor vehicle, and the actual paths followed. In normal use, during braking of the motor vehicle, when the ball 18 remains in contact with the plate member 44, hydraulic brake fluid can flow between the inlet 32 and outlet 26 by way of the various bores 24,30,38,70,86, the apertures 46 in the plate 44, the central aperture 67 in the valve member 20, and the flutes in the thrust member 88. Further, the shoulder 58 on the primary piston 14 abuts the end face 60 of the cylindrical sleeve 34, and the secondary spring 90 biases the ball 18 away from the valve seat 68.When the motor vehicle is empty, and if the inlet pressure exceeds a predetermined level
PA (the cut-in pressure), then the deceleration of the motor vehicle exceeds a predetermined level which causes the ball 18 to move against the biasing force exerted by the secondary spring 90. This movement brings the ball 18 into contact with the valve seat 68 to close the deceleration sensitive proportioning valve 10. If the inlet pressure continues to rise beyond the value PAT then the fluid pressure at the outlet 26 remains constant due to the ball 18 remaining in contact with the valve seat 68. When the inlet pressure reaches a value Pxt the force exerted on the inlet side of the primary piston 14 by the fluid pressure is substantially equal to that exerted on the outlet side of the primary piston.If the inlet pressure continues to rise beyond the value Pxr then the force differential between the inlet side and the outlet side of the primary piston 14 causes the primary piston and the ball 18 to move towards the outlet 26. The pressure at the outlet 26 then rises, but the ball 18 remains in contact with the valve seat 68. The slope of the rise of inlet pressure against outlet pressure during this mode is dependent on the difference in cross-sectional area of the primary piston 14 across the first portion 52 (the first diameter portion of the primary piston 14) and the second portion 54 (the second diameter portion of the primary piston) of the outer surface 50, labelled S1 and S2 respectively.This travel of the primary piston 14 and the ball 18 (which stays in contact with the valve seat 68) continues until the inlet pressure reaches a value Pyt at which point the primary piston abuts the shoulder 104 of the bore 24 by way of the thrust washer 102. Beyond the value Py the primary piston 14 remains in abutment with the second shoulder 104 to prevent further travel, and the ball 18 remains in contact with the valve seat 68. This keeps the deceleration sensitive proportioning valve 10 closed and any further increases in inlet pressure have no effect on the outlet pressure, thereby ensuring the inlet to outlet pressure relationship remains below the ideal curve.
When the motor vehicle is laden, the inlet pressure has to be higher to provide the same amount of deceleration of the motor vehicle when compared to an unladen motor vehicle. In the laden case, the inlet pressure rises beyond PA without causing a deceleration level high enough to move the ball 18.
As the inlet pressure continues to rise, the difference in cross-sectional areas T2 and T1 of the control piston 16 across the second portion 108 and first portion 110 respectively of its outer surface 78 (that is, at the second diameter portion and the first diameter portion respectively of the control piston 16), creates a force which moves the control piston against the biasing action of the primary spring 74. As the primary spring 74 is compressed, so also is the secondary spring 90. As a consequence, the biasing force exerted on the ball 18 by the secondary spring 90 is increased, and a greater value of deceleration is required (when compared to an unladen motor vehicle) to move the ball 18 into contact with the valve seat 68 to close the deceleration sensitive proportioning valve 10.
The combined effects of the control piston 16, primary spring 74 and secondary spring 90 provide a cut-in pressure P3 for a laden motor vehicle which is much closer to the ideal curve than previously known arrangements. Further increases in inlet pressure beyond P have the same effect as described above for an unladen motor vehicle.
The values of the cross-sectional areas T2 and T1 and the rating of the primary spring 74 are chosen so as to provide little, if any, movement of the control piston 16 when the inlet pressure is below PA The rating of the secondary spring 90 is chosen to provide closure of the deceleration sensitive proportioning valve 10 at the required cut-in pressures.
As well as providing the advantage stated above, the present invention, by providing resilient thrust means acting on the ball to bias the ball away from the valve seat, substantially reduces the risk of unintentional ball cut-in due to a vehicle travelling over bumpy or uneven surfaces. This is because travel over a bump will produce a component of force in a vertical direction. With the deceleration sensitive proportioning valve of the present invention mounted in its preferred horizontal arrangement, such a vertical bump force has no effect on moving the ball towards the valve seat, unlike previously known deceleration sensitive proportioning valves which are normally mounted at an angle to the horizontal.
One alternative to the above arrangement would be to omit the thrust member and have the secondary spring act directly on the ball. However, by using the thrust member, the present invention has the additional advantages that the secondary spring is housed completely in the bore in the control piston, thereby avoiding the possibility of spring distortion, and reducing the risk of poor sealing between the valve seat and the ball due to misalignment of the secondary spring and the ball.
Having the thrust member pass through the central aperture in the valve member ensures the direction of force exerted by the secondary spring on the ball remains substantially aligned with the axis of the ball.
In some circumstances an increased length of the slope S1/S2 (see Figure 4) may be required. In this case, the size of the housing may be increased to provide a larger gap between the end of the primary piston and the second shoulder in the stepped bore in the body member, and/or an additional spring may be positioned between this second shoulder and the primary piston.
Various forms of thrust member could be used.
For example, the thrust member may comprise a hollow tube having transversely directed holes, or longitudinally extending slots, formed therein to fluidly connect the inner and outer surfaces of the thrust member.
Claims (10)
1. A deceleration sensitive proportioning valve comprising a housing having a stepped bore means therethrough with an inlet and an outlet; an inertia sensitive member slidably mounted in the stepped bore means adjacent the inlet; a primary piston mounted in the stepped bore means between the inertia sensitive member and the outlet and normally spaced from the inertia sensitive member, the primary piston having a stepped bore therethrough; a valve member positioned in the end of the primary piston directed towards the inertia sensitive member, the valve member being substantially annular and having a central aperture opening into the stepped bore in the primary piston and defining a valve seat engageable with the inertia sensitive member; a control piston slidably mounted in the stepped bore in the primary piston, the control piston having a bore therethrough and having a first diameter portion directed towards the outlet and a second diameter portion directed towards the inertia sensitive member, the first diameter portion having a larger diameter than the second diameter portion; a primary spring positioned in the stepped bore in the primary piston and biasing the control piston towards the outlet and against a stop member secured in the stepped bore; resilient thrust means partially positioned in the bore in the control piston and extending through the central aperture in the valve member to engage the inertia sensitive member, the resilient thrust means comprising a secondary spring engaging a shoulder in the bore in the control piston to exert a biasing force on the inertia sensitive member to normally space the inertia sensitive member from the valve seat.
2. A deceleration sensitive proportioning valve as claimed in Claim 1, wherein the resilient thrust means further comprises a thrust member positioned between, and in engagement with, the secondary spring and the inertia sensitive member.
3. A deceleration sensitive proportioning valve as claimed in Claim 2, wherein the thrust member comprises an elongate body having outwardly directed, longitudinally extending, ribs which are substantially equidistantly spaced apart to define flutes therebetween.
4. A deceleration sensitive proportioning valve as claimed in any one of Claims 1 to 3, wherein the primary piston is slidably mounted in the stepped bore means for limited movement towards and away from the outlet, the primary piston having a first diameter portion directed towards the inertia sensitive member and a second diameter portion directed towards the outlet, the first diameter portion having a smaller diameter than the second diameter portion.
5. A deceleration sensitive proportioning valve as claimed in any one of Claims 1 to 4, wherein a plate member is fixedly positioned in the stepped bore means between the inertia sensitive member and the inlet to limit the travel of the inertia sensitive member towards the inlet.
6. A deceleration sensitive proportioning valve as claimed in any one of Claims 1 to 5, wherein the stop member comprises a circlip fixedly secured in a groove in the stepped bore in the primary piston.
7. A deceleration sensitive proportioning valve as claimed in any one of Claims 1 to 6, wherein the housing comprises a body member having a bore therethrough; an end cap screw-threaded into an open end of the bore in the body member, the end cap having a bore therethrough; and a cylindrical sleeve secured in the bore in the body member between the end cap and a shoulder in the bore in the body member, the cylindrical sleeve having a stepped bore therethrough, the bores in the body member and the end cap and the stepped bore in the cylindrical sleeve defining the stepped bore means, the inertia sensitive member being positioned in the stepped bore in the cylindrical sleeve.
8. A deceleration sensitive proportioning valve as claimed in Claim 7, wherein the bore in the body member defines the outlet and the bore in the end cap defines the inlet.
9. A deceleration sensitive proportioning valve as claimed in any one of Claims 1 to 8, wherein the inertia sensitive member- is a ball.
10. A deceleration sensitive proportioning valve substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9117850A GB2258893A (en) | 1991-08-19 | 1991-08-19 | Deceleration sensitive proportioning valve |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9117850A GB2258893A (en) | 1991-08-19 | 1991-08-19 | Deceleration sensitive proportioning valve |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9117850D0 GB9117850D0 (en) | 1991-10-09 |
| GB2258893A true GB2258893A (en) | 1993-02-24 |
Family
ID=10700184
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9117850A Withdrawn GB2258893A (en) | 1991-08-19 | 1991-08-19 | Deceleration sensitive proportioning valve |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2258893A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2021221A (en) * | 1978-05-09 | 1979-11-28 | Girling Ltd | Vehicle Brake Pressure Control Valve Assemblies |
| US4542945A (en) * | 1982-11-03 | 1985-09-24 | Itt Industries, Inc. | Deceleration-sensitive braking pressure control unit for a vehicular hydraulic brake system |
-
1991
- 1991-08-19 GB GB9117850A patent/GB2258893A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2021221A (en) * | 1978-05-09 | 1979-11-28 | Girling Ltd | Vehicle Brake Pressure Control Valve Assemblies |
| US4542945A (en) * | 1982-11-03 | 1985-09-24 | Itt Industries, Inc. | Deceleration-sensitive braking pressure control unit for a vehicular hydraulic brake system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9117850D0 (en) | 1991-10-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |