Pumps – Expansible chamber type – Having pumping chamber pressure responsive distributor
Patent
1991-10-31
1992-09-15
Smith, Leonard E.
Pumps
Expansible chamber type
Having pumping chamber pressure responsive distributor
417571, F04B 2106
Patent
active
051471892
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a maximum-pressure plunger pump with, coaxial with its longitudinal axis, a compression valve and a suction valve, with a sleeve that floats on a plunger and rests on the end facing the head of the pump on an inset provided with a seat area for the body of the suction valve and with suction channels, whereby the sleeve has a bushing and the suction valve is in the form of a disk with a spring-loaded annular body that rests on the valve-seat area that the suction channels open out of in the insert in the pump head.
A maximum-pressure plunger pump of this genus is known (U.S. Pat. No. 4 174 194). The end of the sleeve that faces the pump head tapers conically in, and the plunger's bushing extends only over the sleeve's cylinder section.
This pump can be used at pressures of up to approximately 1000 bars. At higher pressures, the hydraulic force on the face of the bushing is so powerful that it overcomes the force of adhesion between the bushing and the sleeve. The components become mutually displaced and lead to malfunction.
Compression medium can also penetrate between the bushing and the sleeve, forcing the bushing against the plunger and also resulting in malfunction.
Furthermore, a high surface-to-surface pressure must be maintained between the face of the sleeve and the insert to generate a metallic seal.
The object of the present invention is a maximum-pressure plunger pump of the aforesaid genus that can be operated at pressures of 2000 to 4000 bars on the transition between the sleeve and the insert with little stress on either.
This object is attained in accordance with the invention in that the plunger's bushing extends to the end of the sleeve that faces the head of the pump with its face against the insert and in that a sealing sleeve that overlaps the area of impact between the insert and the sleeve is accommodated in the flow channel demarcated by the bushing and the insert.
The position of the sealing sleeve severely decreases the surface-to-surface pressure in the vicinity of the area of impact between the insert and the sleeve that surrounds the plunger because the pressure of the fluid being conveyed acts toward the area of impact on only a small annular area on the bushing. In the absence of such a sealing sleeve, the materials, even extremely high-quality steels, will reach the limits of their strength very rapidly because a very high surface-to-surface pressure will be required to create a seal at the area of impact.
The sleeve and bushing can also be manufactured as a single unit if a material can be found that simultaneously possesses enough reversed-stresses fatigue strength for the sleeve and the sliding and emergency-operations properties needed for the bushing.
The design in accordance with the invention considerably diminishes the stresses on these components. Depending in fact on the shape of the sealing sleeve and on how thick its wall is, for example, the stresses can be decreased by one half.
Another effect of the sealing sleeve is that it prevents pressure medium from leaking out through the seam between the face of the sleeve around the plunger and the insert, preventing the medium from inducing wear in the aforesaid components that surround the joint.
Further characteristics of the invention will be evident from the subsidiary claims.
One embodiment of the invention will now be specified with reference to the drawing, wherein
FIG. 1 is a longitudinal section through a maximum-pressure plunger pump and
FIG. 2 is an enlarged detail of FIG. 1.
The maximum-pressure plunger pump illustrated in FIG. 1 consists essentially of a housing 1, a head 2 that is connected to the housing, a suction valve 4 and compression valve 5 that are coaxial with the pump's longitudinal axis 3, and a sleeve 7 that floats on a plunger 6 with a bushing 9 in its cylindrical bore 8. The plunger travels back and forth in the bushing.
Bushing 9 extends over the total length of sleeve 7. In the vicinity of the motion of plunger 6, the bushing has an inside diameter D, and, in the vici
REFERENCES:
patent: 4174194 (1979-11-01), Hammelmann
McAndrews Roland
Paul Hammelmann Maschinenfabrik GmbH
Smith Leonard E.
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