Pumps – Combined
Reexamination Certificate
2001-01-24
2003-01-14
Freay, Charles G. (Department: 3746)
Pumps
Combined
C417S312000, C418S181000, C418S206400, C181S241000, C181S264000
Reexamination Certificate
active
06506029
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a gear pump, in particular a power steering pump for the drive unit of a motor vehicle connected to a drive.
BACKGROUND INFORMATION
Gear pumps are used in a variety of ways in modern vehicles. For example, German Published Patent Application No. 196 04 517 describes a gear pump which is used in particular for power shift transmissions in motor vehicles and in which two intermeshing gear wheels are rotatably mounted in a pump housing. Between a suction kidney and a pressure kidney there is an area in which tooth chambers located between the teeth of the gear wheels are mutually sealed by a housing contour surrounding the gear wheels. A resupply device is provided for the gear pump, so that oil under pressure can be supplied through this at least one tooth chamber, which is separated from the suction kidney and pressure kidney in the direction of rotation. The tooth chambers which were not filled completely are thus refilled so that cavitation is prevented.
German Published Patent Application No. 195 33 215 describes a gear pump for the drive unit of a power steering system of a motor vehicle, having a pump housing accommodating two intermeshing gear wheels, each rotatably mounted on a shaft and having a shaft which leads out of the pump housing and is connected to the drive unit. At least one speed reduction step is provided in the drive connection between the gear pump and the drive unit. Noise suppression is achieved because of the reduction of the high rpm of the drive shaft to the low rpm of the gear pump. However, this gear pump still has a relatively large installed volume.
One object of the present invention is to provide a gear pump which can be used in particular as a power steering pump, has a simplified design and thus a small installed volume in combination with lower production costs and also offers the possibility of simple break-in on the test bench.
SUMMARY
The above and other beneficial objects of the present invention are achieved by providing a gear pump as described herein.
Integration of the gear pump and the discharge space in the housing as well as the cover on the attached oil container result in an especially small installed volume and a very simple design.
The partitioned intake space guarantees smooth oil supply, thus reducing the noise generated.
The return flow opens into the attached oil tank, and the pressure limiting valve in the cover sprays from the discharge space into the oil tank, so that the pressure limiting valve may be blocked when breaking in the gear pump on a test bench.
The central transverse bore composed of pressure bores in the discharge space and in the gear pump and a coaxial intake bore outside the center of the pump is drilled at the height of the gland, so that the advantage of symmetrical intake through the bore and slot from the partitioned intake space is achieved, and furthermore, pulsation is reduced due to the deflection of the oil stream on the pressure side.
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Freay Charles G.
Kenyon & Kenyon
Liu Han L.
ZF Lenksysteme GmbH
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