Claims
- 1. In a vehicle having brakes, an engine, a transmission having fluid actuated clutch means having first and second actuating chamber means, and an inching control system having a reservoir, a pump fluidly connected to the reservoir and driven at engine speed, selector valve means fluidly connected to the outlet of the pump and operative to selectively port fluid therefrom to one of said actuating chamber means, and control valve means fluidly connected to the pump for decreasing the pressure applied to the selected actuating chamber means in response to increases in brake actuation forces, an improvement wherein:
- A. a restriction is fluidly connected in series between said pump and a portion of said transmission whereby the outlet pressure of said pump is caused to vary in response to changes in the speed of said engine;
- B. said selector valve means, said control valve means, and said restriction are fluidly connected to the outlet of said pump through a pump outlet conduit in parallel fluid relationship with one another, and
- C. said control valve means is operative to sense brake actuation force and to decrease the outlet pressure of said pump in response to an increase in said actuation force above a predetermined value.
- 2. The improvement as defined in claim 1 wherein said control valve means is further operative, when said brake actuation force is less than said predetermined value, to substantially maintain the outlet pressure of said pump at a predetermined magnitude in response to an increase in the speed of said engine above a predetermined speed.
- 3. The improvement as defined in claim 1 wherein said control valve means is operative to cause an increasing portion of the outlet flow of said pump to bypass said restriction in response to said increases in brake actuation force.
- 4. The improvement as defined in claim 3 and including inching control discharge conduit means for directing said bypass flow portion in parallel flow relationship to said reservoir and to said transmission portion and means for limiting the pressure of said bypass flow portion.
- 5. The improvement as defined in claim 1 wherein said brakes are fluidly actuated and said control valve means includes inlet port means fluidly communicating with the outlet of said pump, discharge port means fluidly communicating with said transmission portion and said reservoir, and a valve member normally biased to a closed position wherein fluid communication between said inlet port means and said discharge port means is prevented and moveable therefrom to positions wherein said fluid communication is permitted, and said control valve means further includes piston means for sensing the actuation pressure of said brakes, said piston means being mechanically connected to said valve member to move said valve member from said closed position in response to increases in said actuation pressure above a predetermined value.
- 6. In a vehicle having brakes, an engine, a transmission having fluid actuated clutch means, having first and second actuating chamber means, and an inching control system having a reservoir, a pump fluidly connected to the reservoir and driven at engine speed, selector value means fluidly connected to the outlet of the pump and operative to selectively port fluid therefrom to one of said actuating chamber means, and control valve means fluidly connected to the pump for decreasing the pressure applied to the selected actuating chamber means in response to increases in brake actuation forces, an improvement wherein:
- A. a restriction is fluidly connected in series between said pump and a portion of said transmission whereby the outlet pressure of said pump is caused to vary in response to changes in the speed of said engine;
- B. said selector valve means, said control valve means, and said restriction are fluidly connected to the outlet of said pump through a pump outlet conduit in parallel fluid relationship with one another, and
- C. said control valve means is operative to sense the pressure in said outlet conduit upstream of said restriction and, upon sensing a given pressure representative of a predetermined engine speed, to substantially maintain said given pressure.
- 7. In a vehicle having brakes, an engine, a transmission having fluid actuated clutch means having first and second actuating chamber means, and an inching control system having a reservoir, a pump fluidly connected to the reservoir and driven at engine speed, selector valve means fluidly connected to the outlet of the pump and operative to selectively port fluid therefrom to one of said actuating chamber means, and control valve means fluidly connected to the pump for decreasing the pressure applied to the selected actuating chamber means in response to increases in brake actuation forces, an improvement wherein;
- A. a restriction is fluidly connected in series between said pump and a portion of said transmission whereby the outlet pressure of said pump is caused to vary in response to changes in the speed of said engine;
- B. said selector valve means, said control valve means, and said restriction are fluidly connected to the outlet of said pump through a pump outlet conduit in parallel fluid relationship with one another, and
- C. said control valve comprises:
- (1) inlet port means fluidly connected to the outlet of said pump;
- (2) outlet port means fluidly connected to means communicating with said reservoir;
- (3) valve means normally biased to a closed position wherein fluid communication between said ports is prevented;
- (4) means for sensing the outlet pressure of said pump and for moving said valve means to an open position wherein fluid communication between said ports is permitted upon sensing an increase in said pressure to a predetermined magnitude corresponding to a given engine speed, thereby substantially maintaining said outlet pressure at said predetermined magnitude; and
- (5) means for sensing the actuation force of said brakes and for moving said valve means from said closed position in response to an increase in said actuation force above a predetermined magnitude to thereby decrease the outlet pressure of said pump.
- 8. The improvement as defined in claim 7 wherein said communicating means comprises:
- A. a first conduit whereby fluid is directed to said transmission portion downstream from said restriction;
- B. a second conduit arranged fluidly in parallel with said first conduit whereby fluid is directed to said reservoir; and
- C. means for limiting the pressure in said first and second conduits.
- 9. The improvement as defined in claim 7 wherein said brakes are fluidly actuated and include fluid cylinder means containing fluid at a pressure proportional to said brake actuation force and wherein said brake sensing and moving means comprises piston means fluidly connected to said fluid cylinder means at one end and abutting said valve means at the other end.
Parent Case Info
This is a continuation of application Ser. No. 732,822, filed Oct. 15, 1976, now abandoned, which is a continuation-in-part of Ser. No. 637,556, filed Dec. 4, 1975, now abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1131032 |
Oct 1968 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
732822 |
Oct 1976 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
637556 |
Dec 1975 |
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