Reciprocating piston pump with radial cylinders based by a wire

Details Reciprocating piston pump with radial cylinders based by a wire Reciprocating piston pump with radial cylinders based by a wire

1996-10-02

1999-04-27

Freay, Charles G.

Pumps

Expansible chamber type

Plural pumping chambers

417273, 92129, 92138, 92148, 92 72, F04B 102

Patent

active

058973028

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention is based on a reciprocating piston pump as set forth hereinafter.
From German Patent Disclosure DE 22 43 137, such a reciprocating piston pump is known, in which two pistons are disposed, facing away from one another, radially to the rotary axis of an eccentric located between them. The pistons are pressed at opposed points against a circumferential face of the eccentric by a C-shaped hoop spring, which is curved around the circumference of the eccentric and whose two ends each engage one piston. For the engagement of the pistons by the hoop spring, the pistons each have a transverse bore, on their ends toward the eccentric, through which the ends of the hoop spring are inserted. The hoop spring is spread open elastically; it is prestressed, and it keeps the pistons in contact with the circumferential face of the eccentric. By rotationally driving the eccentric about its rotary axis, the two pistons are set into a reciprocating motion, in which one piston executes a working stroke at the same time as the other piston executes an intake stroke.
A disadvantage of the known reciprocating piston pump is that the two pistons must be rotated in such a way about their longitudinal axis, for the mounting of the hoop spring, that their through bores will be accessible through an assembly opening for the eccentric in the pump housing so that the ends of the hoop spring can be inserted. The bores of both pistons must also be aligned parallel to one another to allow inserting the hoop spring. Since before the hoop springs are inserted the pistons must be thrust into cylinder bores in the pump housing, only outer face ends of the pistons and on the inside the piston ends protruding into the mounting opening for the eccentric are accessible, making the pistons difficult to grasp so that they can be rotated. After the hoop spring ends have been inserted into the bores of the pistons, the hoop spring must be rotated with the pistons by a quarter turn about the longitudinal axis of the pistons, to allow the eccentric to be mounted in the arc of the hoop spring between the two pistons. Mounting the known reciprocating piston pump is difficult to accomplish and is therefore time-consuming and expensive.


ADVANTAGES OF THE INVENTION

The reciprocating piston pump according to the invention has the advantage that the hoop spring can be mounted in any angular position of the two pistons, and alignment by rotating the pistons about their longitudinal axes becomes unnecessary. The hooklike eyelets are first pressed with their orifices into the annular grooves on the opposed ends of the two pistons, until they snap into place there. The snap connection between the hoop spring and the pistons prevents the hoop spring from coming loose on its own. This enables fast, simple assembly of the reciprocating piston pump of the invention. The hoop spring is a simple bent wire part, which can be produced quickly and inexpensively without wasting material.
In a further feature of the invention, the hoop spring extends past one of its two eyelets. The extension preferably extends approximately tangentially or circumferentially with respect to the eccentric; it lengthens a region of the hoop spring that is curved around the eccentric to beyond the eyelet. Together with a stop face of the pump housing, which is disposed perpendicular to the rotary axis of the eccentric and with little or no spacing from the extension and the curved region of the hoop spring, the extension and the curved region prevent the hoop spring from rotating in the annular grooves of the pistons about their longitudinal axis. At most only a minimal pivoting motion of the hoop spring is possible. As a result, the possibility of a free end of the hoop spring striking an inner wall of the pump housing and wearing away chips from the pump housing in the reciprocating motion is averted. The free end on the eyelet of the hoop spring, which has no extension, does not extend as far as the plane in which the curved region and the extension are located. Th

REFERENCES:
patent: 2271570 (1942-02-01), Pardee
patent: 3259074 (1966-07-01), Erdman
patent: 3514224 (1970-05-01), Budecker
patent: 5573386 (1996-11-01), Schmitt et al.
patent: 5642988 (1997-07-01), Zorn
Spotts, M.F., Design of Machine Elements, Prentice Hall, pp. 156 and 172 (2 pages only), 1969.

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