Pumps – Condition responsive control of pump drive motor – With control of pump drive transmission
Reexamination Certificate
2000-04-14
2001-08-28
Walberg, Teresa (Department: 3742)
Pumps
Condition responsive control of pump drive motor
With control of pump drive transmission
C417S044100
Reexamination Certificate
active
06280147
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to pumps, and more particularly to an apparatus for adjusting the stroke length of a pump element.
BACKGROUND OF THE INVENTION
Often, it is necessary in an industrial or other process to inject a measured quantity of a flowable material into a further stream of material or a vessel. Metering pumps have been developed for this purpose and may be either electrically or hydraulically actuated.
Conventionally, an electromagnetic metering pump utilizes a linear solenoid which is provided electrical pulses to move a diaphragm mechanically linked to an armature of the solenoid. As the solenoid is energized and deenergized, the armature and the diaphragm are reciprocated in suction and discharge strokes over a range of positions. Referring to
FIG. 1
, during each suction stroke, liquid is drawn upwardly through a first fitting
51
past a first check valve
53
and enters a diaphragm recess
55
. A second check valve
57
is closed during the suction stroke. During each discharge stroke, the first check valve
53
is closed and the second check valve
57
is opened, thereby allowing the liquid to travel upwardly past the second check valve
57
and a fitting
59
and outwardly of the pump
21
.
A stroke length adjustment member sets the stroke length of the armature
31
(i.e., the distance the armature travels during each suction and discharge stroke). As shown in
FIG. 1
, the stroke length adjustment member is conventionally a combination of a screw
40
and a knob
42
. The armature
31
rests against an end of the screw
40
at the end of each suction stroke. The position of the end of the screw
40
, and thus the stroke length, can be adjusted by manually rotating the knob
42
in either a first or second direction.
When the pump is not operating, however, the screw
40
can be rotated to shorten the stroke length only when the armature
31
is spaced from the end of the screw
40
, i.e., when the armature is not at the end of a suction stroke. This is because the screw
40
is not capable of providing the required mechanical force to change the stroke length when the armature
31
is in contact with the end of the screw
40
.
SUMMARY OF THE INVENTION
In accordance with the present invention, a metering pump includes an apparatus for manually adjusting the stroke length of a pump element.
More particularly, in accordance with one aspect of the present invention, a pump includes a pump element having a stroke length movable within a range of positions, a circuit for modulating electrical power to a power unit in dependence upon the position of the pump element and an apparatus for adjusting the stroke length of the pump element including a lever wherein the apparatus contacts the pump element at a position within the range of positions to determine the stroke length of the pump element.
Preferably, the pump element includes an armature and the pump further includes a sensor for detecting the position of the pump element. Also preferably, the pump further includes a processor responsive to the sensor for applying electrical power to the pump in dependence upon the position of the pump element.
In addition, the lever preferably includes a first portion which is manually operable and a second portion. The apparatus may also include a cam having a stop surface that is coupled to the second portion of the lever, wherein the stop surface contacts the pump element to determine the stroke length of the pump element. The cam may be coupled to the second portion of the lever by a cap nut and the lever may be coupled to a bracket also by a cap nut. The first portion of the lever may include a locking surface. Furthermore, movement of the lever in a first direction decreases the stroke length of the pump element and movement of the lever in a second direction increases the stroke length of the pump element.
In the preferred embodiment, the pump comprises an electromagnetic metering pump.
In accordance with a further aspect of the present invention, a metering pump having a power unit and an armature movable over a stroke length comprises a sensor for detecting armature position and a driver circuit coupled to the power unit and delivering electrical power to the power unit. A programmed processor is responsive to the sensor for controlling the driver circuit such that electrical power is delivered to the power unit in dependence upon the position of the armature. An apparatus for adjusting the stroke length of the armature includes a lever having a first portion which is manually operable, a second portion and a cam coupled to the second portion. The cam includes a stop surface having a position which is variable as a function of the position of the first portion of the lever wherein the position of the stop surface determines the stroke length.
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Kilayko Enrique L.
Ryan Liam
Liquid Metronics Incorporated
Patel Vinod D.
Walberg Teresa
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