Pumps – With condition responsive pumped fluid control – Fluid flow rate responsive
Patent
1997-12-12
1999-12-14
Freay, Charles G.
Pumps
With condition responsive pumped fluid control
Fluid flow rate responsive
417310, F04B 4908
Patent
active
060009144
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a vane cell pump having a cam ring, supported in the housing, and a rotor with radial slots that is drivable by a drive shaft. Inserted into the radial slots are work slides that sealingly slide radially along in the cam ring. Between the cam ring, the rotor and the work slides, work chambers are formed that are defined in the axial direction by control plates. Built into the housing is a flow regulating valve, acted upon on one side by the delivery pressure against a spring force, which carries oil from a pressure chamber into a spray channel. A further orifice is also provided from the pressure chamber to an outlet channel.
2. Brief Description of the Invention
One such pump is known for instance from German Patent Application DE-A 41 08 126. In the control plate of this pump, an orifice with an orifice insert is provided between the pressure chamber and the outlet channel. This orifice brings about a descending characteristic curve of the flow rate over the rpm. In many cases, however, it is desirable to achieve a constant flow rate characteristic curve, for instance for use in power steering systems.
3. Summary of the Invention
The object of the invention is to attain a horizontal course of the characteristic curve. This object is attained by the characteristic features of the invention. The orifice seated in the outlet channel has a frustum flat face oriented toward the pressure chamber. By means of the frustum flat face, the inflow of oil into the orifice is varied in such a way that the desired constant, horizontal characteristic curve results. By means of the length of the orifice, a viscosity dependency is also attained, and as a result better cold-starting performance of the pump is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in further detail below in conjunction with the drawings shown are:
FIG. 1, a longitudinal section through a vane cell pump according to the invention; and
FIG. 2, the flat face of the orifice on a larger scale.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The vane cell pump is used to feed pressure fluid in the form of oil from a container, not shown, to a consumer, not shown, for instance for a power steering system. In the drawing, a rotor set 3 is inserted into an oil-filled pressure chamber 1 of a housing 2. The rotor set 3 comprises a cam ring 4 and a rotor 5. The rotor 5 is disposed in the interior of the cam ring 4 and has radially oriented slots in which vanes 6 can be displaced. Between the cam ring 4, the rotor 5 and the vanes 6, work chambers are formed which are defined in the axial direction by control faces of adjacent control plates 7 and 8. The pump is embodied as a double-stroke version.
The housing 2 is composed of a bearing housing 10 and an end-loaded housing cap 11. The rotor 5 is seated in a manner fixed against relative rotation on a drive shaft 12 that is supported in the bearing housing 10. The bearing point in the bearing housing 10 is the sole bearing of the drive shaft 12. This means that the drive shaft 12 is not supported in the radial direction in the housing cap 11. The drive shaft is instead supported in the axial direction on the housing cap 11.
Along with an intake connection, not shown, for connecting the container and a pressure connection, also not shown, for the consumer, a flow regulating valve 13 for regulating the pressure fluid carried to the pressure connection is provided in the bearing housing 10. The embodiment of the flow regulating valve 13 and of a pressure limiting valve, also present but not shown, is well known, for instance from U.S. Pat. No. 5,098,259 and will therefore not be described in further detail here. The pressure channels that connect the work chambers to the flow regulating valve 13 and the pressure limiting valve are also disposed in the bearing housing 10. These pressure channels are also well known and will therefore not be described in detail.
According to the invention, the control plate
REFERENCES:
patent: 3385220 (1968-05-01), Dymond
patent: 3989414 (1976-11-01), Rieber et al.
patent: 4207038 (1980-06-01), Strikis
patent: 4298316 (1981-11-01), Strikis
patent: 5209648 (1993-05-01), Ishizaki et al.
Eppli Konrad
Zellner Uwe
Evora Robert Z.
Freay Charles G.
ZF Friedrichshafen AG
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