Pumps – With condition responsive pumped fluid control – Bypass or relief valve controls venting by movable pump...
Patent
1995-08-07
1996-12-31
Gluck, Richard E.
Pumps
With condition responsive pumped fluid control
Bypass or relief valve controls venting by movable pump...
417296, 417297, 417307, F04B 2100
Patent
active
055888097
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
1. Field of the Invention
This invention relates generally to fluid pumps, and more particularly to metering pumps for measuring the delivery of liquids.
2. Discussion of Related Art
A prior metering pump is taught in U.S. Pat. No. 3,680,985. It is in the form of a piston diaphragm pump comprising a comparatively large pump chamber with a suction valve in its lower part, and a vent valve in its upper part, and a comparatively small metering cylinder separated from the pump chamber by a metering piston. The metering piston is seated centrally on a transport diaphragm forming the pump element, and designed to be driven back and forth. A pressure valve branches off from the metering piston to the metering line connector. During the particular compression stroke of the transport diaphragm which corresponds to the metering stroke of the metering piston, a majority of the liquid present in the pump chamber--together with any air present therein--is returned through the return line to the intake container via the vent, and a bypass valve arranged in the upper part of the pump chamber because the displacement volume of the transport diaphragm is several times the displacement volume of the metering piston. This large bypass section not only increases the energy consumption of the pump, it is also responsible for increased wear on important parts of the pump, particularly on the suction and pressure valve.
SUMMARY OF THE INVENTION
One object of the present invention is to provide an improved metering pump with adequate venting of the liquid to be metered, for enabling the necessary return flow of liquid through a vent and bypass valve kept as small as possible, for minimizing the drive energy and the susceptibility to wear.
With the problems of the prior art in mind, the present invention provides an improved metering pump by including between the pressure valve and the pump chamber, a valve chamber separated from the pump chamber by a central nonreturn valve and a displaceable control wall. The vent valve is installed in and controlled by the control wall. The vent valve opens during the suction stroke of the pump element, and closes during the compression stroke thereof. Accordingly, the invention provides a metering pump in which adequate venting of the liquid to be metered, particularly during the startup phase of the pump, is achieved via the valve chamber and the vent and bypass valve branching off therefrom without any need for a significant portion of the liquid taken into the pump chamber and displaced therefrom by the pump element to be returned to the intake container via the vent and bypass valve. Instead, the present metering pump is operated in such a way that after the initial intake and venting phase, virtually the entire volume of liquid transported by the pump element to be metered, is forced into the metering line connector via the pressure valve, while maintaining permanent automatic venting of the valve chamber via its vent and bypass valve independent of the magnitude of metering counter-pressure.
In another embodiment of the invention, a movable displacement wall under pressure is provided in the valve chamber and changes the volume thereof in the opposite direction to the control wall. This ensures that no back suction to the valve chamber is able to occur through the vent and bypass valve, during operation including the particular suction stroke of the pump element, the associated intake movement of the control wall, and the resulting opening of the vent and bypass valve. Such operation occurs at times when the displacement volume of the displacement wall acting as a diaphragm is not as great as the displacement volume of the control wall which also functions as a diaphragm. The displacement volume of the pump element, preferably consisting of a transport diaphragm designed to be driven back and forth, is always greater than that of the control diaphragm, and is preferably greater than twice the displacement volume of the control diaphragm.
The control wall together with the
REFERENCES:
patent: 3680985 (1972-08-01), Ginsberg et al.
patent: 3870436 (1975-03-01), Remy
patent: 4507054 (1985-03-01), Schoenmeyr
patent: 4776771 (1988-10-01), Kern
patent: 4865525 (1989-09-01), Kern
patent: 4990066 (1991-02-01), Kern
Hunklinger Herbert
Klein Joachim
Gluck Richard E.
Jaeschke Wayne C.
Lang Apparatebau GmbH
Szoke Ernest G.
Watov Kenneth
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