US 6,012,903 A · Positive-displacement liquid-metering pump with continuously variable output

Abstract

A piston-type positive-displacement liquid-metering pump with an output-control apparatus for varying the pump output volume per piston stroke by very minute amounts on a smoothly gradual and continuous basis, in which an actuator or actuation portion of the piston has an associated stop structure for limiting its allowable movement to thereby limit the output volume produced on each stroke of the piston, and an indexing member disposed in alignment with the stop structure and having a portion engageable therewith to effect the aforementioned limitation on allowable piston movement and thus define the stroke length of the piston. A continuously variable coupling is operatively disposed between the indexing member and the pump body and/or the indexing member, for changing the effective position of the stop structure relative to the pump body or indexing member and thus changing the allowable length of the piston stroke. Preferably, the stop structure comprises an abutment member such as a spring clip secured along the length of the piston, and the indexing member comprises a co-acting abutment structure disposed in a position to be contacted by the spring clip or other stop carried on the piston. The continuously variable coupling preferably comprises a threaded interconnection between the indexing member and the pump body or a coupling member carried by the body. In a particular preferred embodiment, the threaded connection just noted is implemented by cooperating structures which provide a Vernier-type readout such as that utilized in micrometers, in which an internally threaded barrel-like member has an end extremity which is movable along and relative to an underlying series of indicia, providing a desirable visual indication of the different positions of adjustment resulting from variation of the threaded engagement.

Claims26

Dependent claims

A positive-displacement liquid-metering pump having a continuously variable output, comprising in combination:

a valve body having a metering chamber and a reciprocable piston movable through said chamber to positively displace a volume of liquid therefrom, said displaced volume comprising the output of said pump;
a piston-actuator disposed in alignment with said piston to move it through said chamber in response to an applied force, said piston-actuator extending outwardly of said valve body, and a stop structure associated with said piston-actuator to limit its allowable movement;
an indexing member disposed in alignment with said stop structure and having a portion engageable therewith to limit the allowable movement of said piston-actuator and thereby define the length of stroke of said piston through said chamber;
and
a continuously variable coupling operatively disposed between said indexing member and said valve body for changing the effective position of said stop structure relative to said valve body and thereby changing the allowable movement of said piston-actuator and the stroke length of said piston.

2 more elements

Dependencies are inferred from the claim text.

Positive-displacement liquid-metering pump with continuously variable output

Life of this patent

Positive-displacement liquid-metering pump with continuously variable output

Life of this patent

Abstract

Claims26