Pumps – Expansible chamber type – Having pulsation dampening fluid receiving space
Patent
1999-03-04
2000-08-01
Thorpe, Timothy S.
Pumps
Expansible chamber type
Having pulsation dampening fluid receiving space
F04B 2300
Patent
active
060957735
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a vane cell pump for the delivery of hydraulic oil from a reservoir to a consumer. A pump package, consisting of a rotor, several work slides and a cam ring, has been inserted into an interior chamber of a cup-shaped case top of the vane cell pump. Work chambers, divided by the work slides, are formed between the cam ring and the rotor, which are delimited in the axial direction by control plates. A bearing housing, which contains suction and pressure ducts connecting the work chambers with the suction connector, a flow control valve and a pressure control valve, adjoins the cup-shaped case top on the one side.
BACKGROUND OF THE INVENTION
Such a vane cell pump is known from DE 44 16 077 A1. This pump is distinguished by a sturdy construction and advantageous production/assembly costs. A vane cell pump does not deliver oil continuously, but unevenly in partial volumes per revolution. The cyclically delivered volumes cause pressure fluctuations, pressure vibrations and/or pulsations, in particular on the pressure side. Intake and exhaust shocks, which are generated during the opening and closing of the work chambers, are superimposed on the pressure vibrations.
BRIEF SUMMARY OF THE INVENTION
The invention is based on such a structure of a vane cell pump and has the object of improving the noise conditions caused by the pulsations and pressure fluctuations.
This object is attained by means of the vane cell pump characterized in that the cup-shaped case top arranged on an opposite side of a bearing housing is axially extended and contains a damper for absorbing vibrations. In addition, the case top has an inwardly projecting extension for supporting the pump package. The integration of the damper into the top only requires little additional space, but constitutes a cost-effective, space-saving solution for effective pulsation absorption. The extension which is additionally provided in the housing is used by a control plate, together with the pump package, for support under high pressure and thus for good sealing.
Advantageous embodiments and further damper embodiments are recited hereafter.
Thus, for an improved effect of the damper it is possible to guide a spring-loaded piston on the extension, and the rear chamber created by the piston can be relieved through an absorption bore in the extension. In place of a spring, the piston can also be cushioned against a seal ring. This results in a particularly inexpensive absorbing arrangement.
In accordance with a preferred embodiment a piston, into which several flexible elements have been placed, is provided in the damper. In this embodiment the piston is supported on a sealed housing edge and generates a relief chamber on its rear end. Preferably conical plugs made of a plastic material have been inserted as the flexible elements into appropriate openings, which taper in the direction toward the relief chamber. It has been shown that the flexible elements are suitable for further improved vibration absorption.
In accordance with a further preferred embodiment, an annular groove with a flexible ring is provided in the piston. The annular groove is connected via small bores with a relief chamber. Good results for lowering pressure fluctuations can be achieved by the displacement of the flexible ring into the small bores.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in greater detail in what follows by means of several exemplary embodiments represented in the drawings.
Shown are in:
FIG. 1, a partial cross section through a case top of the vane cell pump in accordance with the invention with a damper chamber;
FIG. 2, a partial cross section in accordance with FIG. 1 with a cushioned piston;
FIGS. 3 and 4, partial cross sections in accordance with FIG. 1, wherein the piston is cushioned against flexible rings;
FIG. 5, a partial cross section in accordance with FIG. 1, wherein the piston contains flexible elements;
FIG. 6, a partial cross section in accordance with FIG. 1 with a flexible ri
Perry Trelita L
Thorpe Timothy S.
ZF Friedrichshafen AG
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