Blind pore piston pump with internal valve and stroke limiting s

Details Blind pore piston pump with internal valve and stroke limiting s Blind pore piston pump with internal valve and stroke limiting s

1996-11-22

1999-04-27

Freay, Charles G.

Pumps

Expansible chamber type

Valved piston

417501, 417552, 417554, F04B 5312

Patent

active

058973036

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention relates to a piston pump with a piston drivable to execute a reciprocating motion, which has a longitudinal bore in which a valve closing body is disposed that is pressed against a valve seat by a valve spring also located in the longitudinal bore.
Such a piston pump is known from international patent disclosure WO 95/00759. In the known piston pump, the valve seat is embodied on a pressure-side mouth of the longitudinal bore of the piston. The valve closing body of the known piston pump has a valve plate, whose sealing face rests on the valve seat when the valve is closed. A shaft extends freely from the valve plate into the longitudinal bore of the piston. The free end of the shaft is engaged by the smaller-diameter end of the winding of a frustoconically wound helical compression spring. The larger-diameter end of the winding is braced against an inner annular shoulder, near the pressure-side mouth of the longitudinal bore of the piston, and thus presses the valve plate against the mouth of the longitudinal bore. This has the disadvantage that the valve plate covers the longitudinal bore, and thus blocks the view of the valve spring located in the longitudinal bore; visually checking the correct seating of the valve spring is thus impossible, or at best difficult. Another disadvantage is that the valve spring covered by the valve plate is not accessible during installation.
To enable installing the valve spring, which is attached to the valve shaft, in the piston, the inner annular shoulder in the longitudinal bore of the piston, which acts as a spring seat, has an interruption or protrusion at one point of its circumference. The valve closing body is introduced into the longitudinal bore together with the valve spring attached to it, with the valve shaft leading, and is rotated. In this process the windings of the frustoconically wound helical compression spring that widen in the direction of the larger-diameter end of the winding come into engagement with the interruption or protrusion of the inner annular shoulder and"screw" into place behind the inner annular shoulder, until the larger-diameter winding end of the helical compression spring has overcome the annular shoulder and rests on the face of the shoulder that points into the longitudinal bore. Such an installation process has the disadvantage that in addition to the axial motion of the valve closing body, a rotary motion is necessary, and assurance must be provided that the valve spring gets all the way behind the inner annular shoulder. The interruption or protrusion of the inner annular shoulder must also be fabricated, which involves additional expense in piston production.


ADVANTAGES OF THE INVENTION

In the piston pump of the invention, the valve closing body is located in the interior of the longitudinal bore of the piston; the valve closing spring is located on the side toward the pressure-side mouth of the longitudinal bore, which has the advantage that the valve spring is visible through the pressure-side mouth of the longitudinal bore of the piston, through which the installation of the valve closing body and the valve spring is accomplished, and its correct seating can be checked by sight. Installation does not have to be done "blind", and the valve spring is directly accessible during installation. Another advantage of the invention is that the closing spring is installed longitudinally of the piston; a rotary motion is unnecessary.
An inner annular shoulder, which may also be part of an inner flange, and which is embodied in either fully encompassing or split form can serve as the spring seat. It is also possible for radially inwardprotruding lugs, distributed over the circumference of the longitudinal bore of the piston, to serve as the spring seat.
The valve spring continues, from its windings acting as a spring and located between the valve closing body and the spring seat, on through the larger-diameter end of the winding resting on the spring seat, into a stroke limiting portion of small diameter wh

REFERENCES:
patent: 5067880 (1991-11-01), Finsterwalder et al.
patent: 5110271 (1992-05-01), Hofman
patent: 5562430 (1996-10-01), Schuller et al.
patent: 5588817 (1996-12-01), Zirps et al.
patent: 5688113 (1997-11-01), Bareiss et al.

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