Expansible chamber devices – Collapsible chamber wall portion – Wall portion formed of flexible material
Reexamination Certificate
2000-01-19
2001-12-11
Ryznic, John E. (Department: 3745)
Expansible chamber devices
Collapsible chamber wall portion
Wall portion formed of flexible material
Reexamination Certificate
active
06327960
ABSTRACT:
The invention relates to a diaphragm pump with a hydraulically driven diaphragm according to the preamble of claim 1.
In future, it will be possible for growing environmental protection requirements, together with strict legal conditions, to be satisfied usually only by means of hermetically sealed process installations. Leak-free fluid working machines, such as, for example, pumps and compressors, are of great importance in this context. Diaphragm pumps are an optimum solution, in particular, for the conveyance of toxic, hazardous, irritating, sensitive, abrasive, corrosive fluids and also for aseptic conditions. The diaphragm, as the central element, performs a double function as a static seal and a displacer in the form of an elastic conveying space wall. The static diaphragm seal is the basis for the hermetic leaktightness of diaphragm pumps. Furthermore, the diaphragm transmits the oscillating stroke movement of a drive to the fluid to be conveyed, thus giving rise not only to pulsating conveyance, but also to interaction with the fluid masses in the pipeline system. In the case of diaphragm pumps with a hydraulic diaphragm drive, the oscillating movement of a drive member is transmitted to the diaphragm via a hydraulic reservoir which comprises a hydraulic fluid. The hydraulically driven diaphragm always operates with pressure equalization and has to undergo only deflection stresses.
Diaphragms for hydraulic diaphragm pumps are to be as deformable as possible, in order to enclose as much volume as possible between the limits of positive and negative deformation. In this case, however, local bulging of the diaphragm may occur in an undesirable way. This results in locally high alternating bending stresses which lead relatively quickly to material fatigue.
The object on which the invention is based is to improve a diaphragm pump with a hydraulically driven diaphragm of the abovementioned type, in such a way that two concurrent conditions for the diaphragm are satisfied, specifically, on the one hand, the highest possible deformability which makes it possible to cover the largest possible volume during the working movement, and, on the other hand, a minimal tendency to local bulging actions during the movement.
This object is achieved, according to the invention, by means of a diaphragm pump of the above-mentioned type, having the features characterized in claim 1. Advantageous refinements of these are described in the further claims.
In a preferred embodiment, the waves are formed concentrically around the center point of the diaphragm. This results in a rotationally symmetric stress load on the diaphragm during operation.
There is provision, according to the invention, for the wavelength and/or the amplitude of the wavy formation of the diaphragm to be made variable in the radial direction.
The advantage of this is that, whilst the diaphragm has sufficient deformability for operating with a large stroke, sufficient rigidity against the formation of local bulges is ensured at the same time. The operating reliability and useful life of the diaphragm pump are increased thereby.
Expediently, starting from the center point of the diaphragm in the radially outward direction, the wavelength and/or the amplitude increases or first increases, reaches a maximum and then falls (decreases) again.
Supporting surfaces delimiting a working space of the diaphragm are provided for the appropriate support of the diaphragm, at least the supporting surface located on the hydraulic side having a bearing contour for the diaphragm in the deflected position of the latter, said bearing contour corresponding essentially to the wavy formation of the diaphragm. As a result, the diaphragm bears on the supporting surfaces not only with its wave crests, but over a large part of the contour. This appreciably improves the support, so that the diaphragm, without being damaged, can be pressed with pressure, for example, against the supporting surface or bearing support located on the hydraulics side.
The diaphragm is produced, for example, from an at least partially plastomeric or elastic material, in particular PTFE or PE.
In a preferred embodiment, starting from the center point of the diaphragm, as from 30% of the outer radius, a wavelength of the wavy formation is 6% to 13% of the radius and an amplitude of the wavy formation is 2% to 6% of the radius.
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Patent Abstracts of Japan vol. 1998, No. 03, (Feb. 27, 1998) and JP 09 286659, Applicant NGK Spark Plug Co Ltd, Nov. 4, 1997.
Heimueller Ralph
Schluecker Eberhard
Jacobson & Holman PLLC
LEWA Herbert Ott GmbH & Co.
Ryznic John E.
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