Proportioning brake control device with bypass

• US 3,937,523 A
• Filed: 11/29/1974
• Issued: 02/10/1976
• Est. Priority Date: 08/30/1973
• Status: Expired due to Term

• Current Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Doerfler, Roger E., Stelzer, William, Ayers, David T. Jr.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Butler, Douglas C.
• Application Number:
  US05/528,475
• Time in Patent Office: 438 Days
• Field of Search: 303/6 C, 303/6 R, 303/84, 188/349, 188/151 A, 137/110
• US Class Current: 303/9.72
• CPC Class Codes: B60T 11/34 Pressure reducing or limiting valves for arrangements for adjusting wheel-braking force responsive to vehicle weight or load B60T8/1831
• CPC Class Codes: B60T 8/26 characterised by producing differential braking between front and rear wheels using electrical circuitry or regulation means B60T8/17

Abstract

A device for varying the proportion of brake pressure delivered to the front and rear brakes of a vehicle, and including a differential area piston for decreasing the proportion delivered to the rear brakes between the first and second inlet pressures, and an additional valve assembly actuatable in response to a predetermined pressure differential between the fluid pressure delivered to the piston and the fluid pressure delivered thereby to the rear brakes so as to establish a decreasing pressure differential between the pressure delivered to the front and rear brakes.

Claims

1. A device for a dual brake system including a master cylinder and front and rear brake actuators,

said device being located in said system between said master cylinder and said rear brake actuator and including,

a housing having a first bore, a fluid inlet adapted to receive fluid from said master cylinder and a fluid outlet through which fluid is adapted to be displaced to said rear brake actuator, said inlet being communicable with one portion of said first bore and said outlet being communicable with another portion of said first bore,

first valve means actuatable in response to fluid pressure at said inlet in excess of a first predetermined pressure for decreasing the transmission of fluid pressure from said inlet to said outlet,

said first valve means being disposed in a second bore different from said first bore,

second valve means having a first area exposed to the fluid pressure at said outlet and a second area different from said first area exposed to the fluid pressure at said inlet and actuatable in response to a predetermined pressure differential between said inlet and said outlet to provide a flow path circumventing said first valve means and permitting fluid to flow directly from said inlet to said outlet,

said second valve means being disposed in said first bore and movable longitudinally therein to provide said direct flow path, and

bypass means in said first bore for sensing a predetermined pressure condition in an ancillary brake system for providing a direct flow path from said inlet to said outlet and bypassing said first and second valve means.

2. The invention as set forth in claim 1 wherein said first valve means comprises a proportioning valve.

3. The invention as set forth in claim 2 wherein one of said areas of said second valve means is exposed to the outlet pressure from said proportioning valve.

4. The invention as set forth in claim 1 which includes means resiliently biasing said second valve means toward a position blocking said flow path.

5. The invention as set forth in claim 1 wherein said first valve means has a first total area exposed to fluid pressure at said inlet and a second total area exposed to fluid pressure at said outlet, and wherein the ratio of said first and second total areas is established so as to provide movement of said valve means in response to fluid pressure at said inlet.

6. The invention as set forth in claim 5 wherein said second total area is greater than said first total area of said first valve means.

7. The invention as set forth in claim 1 which includes means within said bore resiliently biasing said second valve means toward said inlet.

8. The invention as set forth in claim 1 wherein the larger of said areas is exposed to fluid pressure at said inlet, and wherein a portion of said second valve means is exposed to the atmosphere.

9. The invention as set forth in claim 1 wherein said another portion of said bore is communicable with one side of said first valve means.

10. The invention as set forth in claim 9 which includes spring means resiliently biasing said second valve means toward said portion of said bore communicable with said first valve means.

11. The invention as set forth in claim 1 wherein said first valve means comprises a proportioning valve having a valve member movable along a first axis and wherein said second valve means comprises a valve element movable along an axis different from said first mentioned axis.

12. The invention as set forth in claim 11 wherein the inlet of said second valve means comprises the outlet of said proportioning valve.

13. The invention as set forth in claim 11 wherein the inlet of said second valve means is communicable with the inlet of said proportioning valve.

14. The invention as set forth in claim 1 wherein said first valve means comprises a first proportioning valve and said second valve means comprises a second proportioning valve.

15. The invention as set forth in claim 1 wherein the axis of said second bore is substantially perpendicular to the axis of said central bore.

16. A device for a dual brake system including a master cylinder and front and rear brake actuators,

said device being located in said system between said master cylinder and said rear brake actuator and including,

a housing having a fluid inlet adapted to receive fluid from said master cylinder and a fluid outlet through which fluid is adapted to be displaced to said rear brake actuator,

a first modulating valve assembly having an inlet communicable with said fluid inlet and an outlet communicable with said fluid outlet,

said first valve assembly being adapted for movement in response to fluid pressure at said fluid inlet for decreasing the transmission of fluid pressure from said fluid inlet to said fluid outlet,

a second modulating valve assembly having a valve member with a first area exposed to the fluid pressure at said outlet of said first valve assembly and a second area exposed to the fluid pressure at the inlet of said first valve assembly,

means defining a first flow path from said fluid inlet to the inlet of said first valve assembly and from the outlet of said first valve assembly through said second valve assembly and finally from said second valve assembly to said fluid outlet,

said valve member of said second modulating valve assembly being actuatable in response to a predetermined fluid pressure differential between said inlet and outlet of said first valve assembly to provide a second flow path at least partially different from said first flow path for communicating fluid directly from said fluid inlet to said fluid outlet, and

bypass means for sensing a predetermined pressure condition in an ancillary brake system for providing a direct flow path from said fluid inlet to said fluid outlet and bypassing said first and second valve assemblies.

17. The invention as set forth in claim 16 wherein said first modulating valve assembly includes differential area means adapted for movement in response to fluid pressure at said fluid inlet for decreasing the transmission of fluid pressure from said fluid inlet to said fluid outlet, and which includes resilient means for applying a force to said differential area means for preventing movement of said differential area means and consequent decreasing the transmission of fluid pressure thereby below a first predetermined fluid level at said fluid inlet, said resilient means yielding to allow movement of said differential area means to decrease the transmission of fluid pressure from said fluid inlet to said fluid outlet above said first predetermined fluid pressure level.

18. The invention as set forth in claim 16 which includes means resiliently biasing said valve member of said second valve assembly toward a position blocking said second flow path.

19. The invention as set forth in claim 16 wherein said housing is formed with a bore, wherein said fluid inlet is communicable with one portion of said bore and said fluid outlet is communicable with another portion of said bore, wherein said second valve assembly is disposed in said bore and is movable longitudinally therein to open and close said second flow path.

20. The invention as set forth in claim 19 which includes means within said bore resiliently biasing said second valve means toward said fluid inlet.

21. The invention as set forth in claim 20 wherein said first valve assembly includes a valve member having first and second areas exposed to said fluid inlet and said fluid outlet and wherein the larger of said areas is exposed to fluid pressure at said outlet.

22. The invention as set forth in claim 16 wherein said housing is formed with a bore, wherein said second valve means is disposed in said bore, and wherein a portion of said bore is communicable with said fluid outlet and another portion of said bore is communicable with one side of said first valve assembly.

23. The invention as set forth in claim 22 which includes spring means resiliently biasing said valve member of said second valve assembly toward said portion of said bore communicable with said first valve assembly.

24. The invention as set forth in claim 23 wherein said first valve assembly comprises a proportioning valve having a valve member movable along a first axis and wherein said valve member of said second valve assembly is movable along an axis different from said first mentioned axis.

25. A device for a dual brake system including a master cylinder and front and rear brake actuators,

said device being located in said system between said master cylinder and said rear brake actuator and including,

a housing having a central longitudinal bore and a second bore different from said central bore,

said housing having a fluid inlet and a fluid outlet, said inlet adapted to receive fluid from said master cylinder and being communicable with one portion of said central bore, and said outlet adapted to displace fluid to said rear brake actuator and being communicable with a second portion of said central bore,

first proportioning valve means actuatable in response to fluid pressure at said inlet in excess of a first predetermined pressure for decreasing the transmission of fluid pressure from said inlet to said outlet,

said first proportioning valve means being disposed in said second bore and being movable longitudinally therein,

second proportioning valve means being disposed in said central bore and being movable longitudinally therein,

means defining a first flow path from said fluid inlet to the inlet of the first proportioning valve means and from the outlet of said first proportioning valve means through at least part of said second proportioning valve means and finally to said fluid outlet,

said second proportioning valve means actuatable in response to a predetermined pressure differential between said inlet and said outlet to provide a second flow path at least partially different from said first flow path and circumventing said first proportioning valve means and permitting fluid to flow directly from said inlet to said outlet,

bypass means for sensing a predetermined pressure condition in an ancillary brake system for providing a direct flow path from said fluid inlet to said fluid outlet and bypassing said first and second proportioning valve means, and

said bypass means being disposed in said central bore and being movable longitudinally therein in substantial coaxial relationship with said second proportioning valve means.

26. The invention as set forth in claim 25 wherein the axis of said second bore is perpendicular to the axis of said central bore.

27. The invention as set forth in claim 25 which includes means resiliently biasing said second proportioning valve means toward a position blocking said second flow path.

28. The invention as set forth in claim 25 wherein said first proportioning valve means has a first total area exposed to fluid pressure at its inlet and a second total area greater than said first total area exposed to fluid pressure at its outlet, and wherein the ration of said first and second total areas is established so as to provide movement of said first proportioning valve means in response to fluid pressure at its inlet.

29. The invention as set forth in claim 25 which includes means within said central bore resiliently biasing said second proportioning valve means toward said inlet.

30. The invention as set forth in claim 25 wherein said second proportioning valve means has a third total area exposed to fluid pressure at its outlet and a fourth total area larger than said third total area exposed to fluid pressure at its inlet.

31. The invention as set forth in claim 25 wherein the inlet of the second proportioning valve means is communicable with the inlet of the first proportioning valve means.