Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Reexamination Certificate
1999-08-11
2001-01-16
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
C137S115160, C137S115200
Reexamination Certificate
active
06173730
ABSTRACT:
This invention relates to a valve through which fluid flows from a source to charge an accumulator in a brake system and which allows fluid to flow from the conduit to a reservoir in the absence of flow of fluid from the source.
BACKGROUND OF THE INVENTION
In brakes systems it has become a common practice to include a traction control function along with anti-lock brake capabilities. The traction control function utilizes may of the components necessary to achieve the anti-lock brake capabilities. However, in order for the traction control function to achieve a desired level of operation, an accumulator is often included in the brake system. The accumulator is charged to a desired pressure level by the operation of a pump in the brake system. In charging the accumulator fluid is communicated from the pump through a flexible conduit. Unfortunately, the fluid pressure developed by the pump to charge the accumulator is maintained in the conduit even after the pump has been turned off and as a result after a period of time and under some conditions it is possible that a leak may occur in the flexible conduit. In order to relieve the fluid pressure in the conduit it has been suggested that the flexible conduit be permanently connected to a reservoir through a restricted orifice. This permanent connection allows the fluid pressure in the conduit to bleed to reservoir pressure over a period of time. Unfortunately this permanent connection also allows a portion of the fluid supplied to the accumulator by the pump to flow to the reservoir during the charging function and as a result the efficiency of the pump is reduced by this flow to the reservoir.
SUMMARY OF THE INVENTION
In order to utilize the full capacity of a pump to charge an accumulator, the present invention has a valve which allows the entire output of a pump to flow to an accumulator during a charging operation and when the flow from the pump terminates thereafter allows fluid to flow from a flexible conduit to a reservoir. The valve has a housing with a first bore therein connected to the pump through an entrance port, to the accumulator through an exit port and to the reservoir through an exhaust port. A sleeve located in the first bore has a first end adjacent the entrance port and a second end adjacent the exhaust port. A second bore in the sleeve which extends from the first end to the second end has a central diameter section separated from a first end diameter section by a first shoulder and from a second end diameter section by a second shoulder. A first ball located in the first end diameter section is urged by a first spring toward the first shoulder. A flange on the second end of the sleeve retains a second ball in the second diameter section of the sleeve. Linkage located in the central diameter section has a first end, which engages the first ball, and a second end, which engages the second ball. A second spring located in the first bore urges the sleeve toward the entrance port to allow the first spring to seat the first ball on the first shoulder. With the first ball seated fluid communication is prevented through the central diameter section while permitting free communication between the exit port and the exhaust port to allow fluid in the conduit to flow to the reservoir. When the pump is activated fluid flow is communicated to the entrance port. The pressure of the fluid presented to the entrance port develops a charging force which acts on the first end of the sleeve and after overcoming the second spring initially moves the sleeve toward the exhaust port. As the sleeve approaches the exhaust port, the second ball is first to engage an exhaust seat surrounding said exhaust port. On engagement of the second ball with the seat fluid communication from the first bore to the reservoir is interrupted. Further movement of the sleeve occurs as the second spring is compressed, however, the second ball remains in a stationary position on the exhaust seat and the first ball which is connected by the linkage to the first ball also remains stationary as the first spring is now compressed with a charging seat of the first shoulder moving away from the first ball to allow fluid to flow to the accumulator by way of the second bore and exhaust port. When the accumulator is charged, flow of fluid through the second bore terminates and the fluid pressure across the sleeve equalizes such that the second spring moves the sleeve toward the entrance port and again initiate communication between the exit port and exhaust ports as the first ball is again seated on the charging seat.
An advantage of the present invention is provided by limiting the time that a flexible conduit is under high pressure.
An object of this invention is to provide a valve for charging an accumulator and for bleeding a flexible conduit when the accumulator is charged to utilize a full capacity of a pump while limiting the exposure of a conduit to high pressure.
A further advantage of this invention resides in a valve, which sequentially closes a flow communication path between an exit port and an exhaust port while opening a communication path between an entrance port and the exit port to supply pressurized fluid to an accumulator.
REFERENCES:
patent: 3604446 (1971-09-01), Brooks
patent: 3845776 (1974-11-01), Ueda
patent: 3939859 (1976-02-01), Ueda et al.
Comstock Warren
Hepperle Stephen M.
McCormick Jr. Leo H
Robert Bosch Corporation
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