Pumps – Three or more cylinders arranged in parallel – radial – or... – Radial cylinders
Reexamination Certificate
1999-10-15
2001-09-04
Freay, Charles G. (Department: 3746)
Pumps
Three or more cylinders arranged in parallel, radial, or...
Radial cylinders
C417S470000
Reexamination Certificate
active
06283724
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a piston pump which is intended for use particularly in a slip-controlled hydraulic vehicle brake system.
One such piston pump is known from German patent application DE 41 07 979 A1. The known piston pump has a pump housing, into which a bush is inserted. A piston is axially displaceably received in the bush and can be driven to execute an axially reciprocating stroke motion by mean of an eccentric element that can be driven to rotate by an electric motor. The known piston pump has an inlet valve and an outlet valve that control a flow direction of fluid pumped by the piston pump; in the known piston pump, these valves are embodied as spring-loaded check valves. The outlet valve is disposed on the outlet side of a bush bottom that is integral with the bush. The inlet valve is disposed on a piston face end that is located in the bush and faces toward the bush bottom. The fluid inlet takes place through the piston, which to this end has intersecting transverse bores and is provided with an axial blind bore, beginning at these transverse bores, that leads to a valve seat of the inlet valve.
OBJECT AND SUMMARY OF THE INVENTION
In the piston pump of the invention, both of the valves that control the flow direction are disposed on or in the bush. This has the advantage that geometrically, the piston can take the form of a cylinder and can be produced without any bore, undercut, or the like at all, and hence can be made economically. A roller or needle of a roller or needle bearing can for instance be used as the piston; these parts, being mass-produced, can be procured inexpensively.
Another advantage is that no valve is disposed on the piston; this reduces the mass to be moved when the piston pump is in operation. The opening and closing performance of the valve, which in the invention is stationary inside the bush, is more favorable than a valve mounted on the piston, which necessarily goes along with the reciprocating motion of the piston, thus subjecting a valve closing body to considerable acceleration.
The piston pump of the invention is intended in particular as a pump in a brake system of a vehicle and is used to control the pressure in wheel brake cylinders. Depending on the type of brake system, the abbreviations ABS, TCS, ESP and EHB are used for such brake systems. In the brake system, the pump serves for instance to return brake fluid from one or more wheel brake cylinders to a master cylinder (ABS) and/or to pump brake fluid out of a supply container into one or more wheel brake cylinders (TCS or ESP or EHB). The pump is needed for instance in a brake system with wheel slip control (ABS or TCS) and/or a brake system serving as a steering aid (ESP) and/or an electrohydraulic brake system (EHB). With wheel slip control (ABS or TCS), locking of the wheels of the vehicle during a braking event involving strong pressure on the brake pedal (ABS) and/or spinning of the driven wheels of the vehicle in the event of strong pressure on the gas pedal (TCS) can for instance be averted. In a brake system serving as a steering aid (ESP), a brake pressure is built up in one or more wheel brake cylinders independently of an actuation of the brake pedal or gas pedal, for instance to prevent the vehicle from breaking out of the track desired by the driver. The pump can also be used in an electrohydraulic brake system (EHB), in which the pump pumps the brake fluid into the wheel brake cylinder or cylinders if an electric brake pedal sensor detects an actuation of the brake pedal, or in which the pump is used to fill a reservoir of the brake system.
REFERENCES:
patent: 3597119 (1971-08-01), Gratzmuller
patent: 5123819 (1992-06-01), Schuller et al.
patent: 5125808 (1992-06-01), Sekiguchi
patent: 5213482 (1993-05-01), Reinartz et al.
patent: 5232273 (1993-08-01), Eckstein
patent: 5320498 (1994-06-01), Fuchida
patent: 5947441 (1999-09-01), Zenker et al.
patent: 6079961 (2000-06-01), Schuller et al.
patent: 6126418 (2000-10-01), Sinnl
patent: 19 11 534 A (1970-09-01), None
patent: 41 07 979 A1 (1992-09-01), None
Alaze Norbert
Fritsch Siegfried
Weh Andreas
Freay Charles G.
Gray Michael K.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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