Pumps – Expansible chamber type – Having pulsation dampening fluid receiving space
Patent
1990-08-10
1992-03-17
Bertsch, Richard A.
Pumps
Expansible chamber type
Having pulsation dampening fluid receiving space
417542, F04B 1100
Patent
active
050964003
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention is related to a damping device for hydraulic positive-displacement pumps.
BACKGROUND OF THE INVENTION
Due to the intermittent drive of the recuperator piston, hydraulic positive-displacement pumps generate pressure pulsations which, create undesirable noise.
Such pumps serve, for example, for the hydraulic fluid supply of hydraulic brake units or of hydraulic power steering assemblies in automotive vehicles. The damping device serves to reduce pulsations of the pressure and of the delivery flow. Damping devices are employed both for the purpose of noise reduction and to avoid pressure surges in the system to be operated. A pump of this kind is known from German published patent application No. 32 09 296, the damping device being, however, configurated in the shape of an additional damping chamber requiring considerable space and including a housing of its own with guiding devices incorporated therein.
In another prior-art positive-displacement pump (German printed and examined patent application No. 15 28 359) an elastic element enclosing a gas volume is positioned both in the range of the suction connection and in the range of the delivery connection for damping of the pressure pulsation. Although suction-side pressure pulsations can be damped in a satisfactory manner by the use of an enclosed compressible gas cushion since the pressure pulsations take place at a very low pressure level, no appreciable damping of pulsations can be achieved by the disclosed arrangement in the delivery range, in particular as far as high pressure pumps are concerned, since the gas cushion loses its damping capacity very rapidly as the pressure rises.
SUMMARY OF THE INVENTION
It is, therefore, the object of the invention to provide a hydraulic pump of the kind mentioned above which features a simple and compact design and simultaneously guarantees a particularly low pressure pulsation, being, at the same time, distinguished by a particularly sturdy design.
This object is attained in a preferred embodiment of the present invention, in which the duct is connected to the annular chamber square with the blind-end bore. A sharp deviation of the delivery flow is achieved in this manner, as a result whereof the degree of damping is increased. A further deviation of the hydraulic fluid flow is attained in that the outlet openings are routed radially out of the closing element toward the outside.
A further improvement of the damping quality is achieved in that the outlet openings end up in a collecting chamber positioned in the cylinder block. In one embodiment of the invention offering particular ease of mounting the annular chamber and the collecting chamber are divided from each other by the screw coupling of the closing element. A decisive improvement of the damping is achieved when an elastic element is positioned between the outlet valve and the pump outlet. In this manner, a pulsation damping is obtained by the elastic deformation of an elastomeric shaped element which protrudes into a cavity under the effect of pressure. Besides the compressibility of the elastomer, the property of absorbing energy of deformation is utilized.
This characteristic of the damping device can be varied by the particular shape of the elastomeric element or by the contour of the rigid wall which is preferably located at the pump housing or at a closing element being associated with the pump housing.
Depending on the desired elastic, and corresponding damping properties, the cavity may contain an enclosed volume of air or may be connected to the ambient air by means of an atmosphere bore.
The damping characteristic cam be influenced in an especially effective way when a spring element is placed between the shaped element and the rigid wall. The effect of the pressure chamber acting as a damping chamber can be increased when a restriction point is provided between the delivery-side connection and the pressure chamber. That restriction point may be placed in the valve housing of a non-return valve being posi
REFERENCES:
patent: 3366067 (1966-04-01), Kocolowski
patent: 4721444 (1988-01-01), Pareja
Budecker Ludwig
David Anton
Guse Hans-A.
Obersteiner Georg
Schweighoefer Bernd
Alfred Teves GmbH
Bertsch Richard A.
Freay Charles G.
Lewis J. Gordon
Seitter Robert P.
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