Pumps – Processes
Reexamination Certificate
1999-05-11
2001-04-03
Freay, Charles G. (Department: 3746)
Pumps
Processes
C092S060500
Reexamination Certificate
active
06210121
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to metering pumps, and more particularly, to a method of calibrating a lost-motion metering pump.
BACKGROUND ART
In order to minimize the variation in output flow of hydraulic lost-motion metering pumps from one pump to another, it is necessary to perform a calibration procedure on each pump. The parameter that a user is most concerned with is the amount of fluid that is pumped over a given time. This parameter, in turn, is determined by the physical relationship between a bypass hole located in a hollow plunger and a control rod extending into the hollow plunger. Currently, this relationship is adjusted during a calibration procedure, which is conducted before filling of a pump reservoir, by an air gauging setup. Briefly, the air gauging setup measures the pressure drop across the bypass hole when the hollow plunger is disposed at a certain position. If a standardized pressure drop value is used for all pumps of a given configuration, then one can be assured that flow performance variations will be minimized. This pressure drop is related to the amount of air flowing through the bypass hole, which is, in turn, related to the equivalent size of the bypass hole when the plunger is at the certain position. The size of the bypass at the time that the plunger is disposed at the certain position can be adjusted by changing the position of the control rod relative to the bypass hole. Typically, a stamped metal linkage is bent to accomplish the actual adjustment of control rod position.
Bending the metal linkage to obtain the desired pressure drop value is a lengthy and tedious process. In addition, calibration must be performed very early in the assembly process. If it ever becomes necessary to re-calibrate the pump, substantial disassembly of the pump is required. Furthermore, if re-calibration of the pump is required once the pump is installed, either the pump will have to be returned to the manufacturer or an air gauge setup will have to be provided at the installation site.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a method of calibrating a lost-motion metering pump is provided wherein the pump includes a relief port, a movable hollow plunger having a bypass hole which is aligned with the relief port when the plunger is moved to an aligned position and a control rod extending into the hollow plunger. The method includes the steps of moving the plunger to the aligned position, inserting a gage pin through the relief port and the bypass hole into the plunger, moving the control rod into engagement with the gage pin and fixing the position of the control rod.
Preferably, the step of fixing comprises the step of threading a retention nut into a control rod bore in which the control rod is disposed. Also preferably, the control rod includes a bore that receives an anti-rotation pin and the method includes the further step of inserting a hollow seal cap having a slot into a pump housing and the step of moving the control rod comprises the step of inserting the control rod through the hollow seal cap such that the anti-rotation pin is disposed in the slot. Still further in accordance with the preferred embodiment, the step of fixing comprises the steps of inserting a hollow knob having a circumferential flange into the pump housing such that the hollow knob surrounds a portion of the control rod and a portion of the seal cap, securing the hollow knob to the control rod and threading a retention nut into the pump housing to capture the circumferential flange against the seal cap.
A threaded ring is preferably threaded onto the control rod and the step of securing the hollow knob to the control rod comprises the step of threading a set screw into engagement with the threaded ring.
In accordance with another aspect of the present invention, a method of calibrating a lost-motion metering pump is provided wherein the pump includes a pump housing having a control rod bore, a relief port formed in the pump housing and adapted to receive a relief valve assembly, a movable hollow plunger having a bypass hole which is aligned with the relief port when the plunger is moved to an aligned position and a control rod extending into the control rod bore and the hollow plunger. The method comprises the steps of moving the plunger to the aligned position, inserting a gage pin through the relief port and the bypass hole into the plunger while the relief valve assembly is removed from the relief port and inserting a hollow seal cap having a slot into the control rod bore. The control rod is placed into the control rod bore through the seal cap and into engagement with the gage pin. The position of the control rod is fixed by inserting a hollow knob having a circumferential flange into the second bore surrounding a portion of the control rod and a portion of the seal cap, securing the hollow knob to the control rod and threading a retention nut into the second bore to capture the circumferential flange and the seal cap against the pump housing.
In accordance with yet another aspect of the present invention, a method of calibrating a flow control assembly of a lost-motion pump is provided wherein the flow control assembly includes a control rod and a knob and the lost-motion pump includes a hollow plunger disposed in a pump housing. The method includes the steps of inserting the control rod into the hollow plunger, advancing the control rod into the hollow plunger until a particular portion of the control rod is aligned with respect to a certain portion of the pump housing and securing the knob to the control rod when the control rod is aligned with respect to the pump housing.
In accordance with a still further aspect of the present invention, a method of calibrating a flow assembly of a lost-motion pump wherein the flow control assembly includes a control rod and a knob and wherein the lost-motion pump includes a relief valve port and a hollow plunger disposed in a pump housing and having a bypass hole, includes the steps of advancing the hollow plunger to an extreme position such that the bypass hole is aligned with the relief port and installing a gauge pin through the relief valve port into the bypass hole. The control rod is inserted into the hollow plunger until the control rod contacts the gauge pin and an indicator is applied to at least one of the flow control assembly and the pump at an aligned position while the control rod is contacting the gauge pin to calibrate the flow control assembly.
In accordance with yet another aspect of the present invention, a method of calibrating a flow control assembly of a lost-motion pump, the flow control assembly including a control rod and a knob and the lost-motion pump including a hollow plunger disposed in a pump housing, includes the steps of inserting the control rod into the hollow plunger and advancing the control rod into the hollow plunger until a particular portion of the control rod is aligned with respect to a certain portion of the pump housing. An indicator is secured to at least one of the flow control assembly and the pump at an aligned position while the particular portion of the control rod is aligned with the certain portion of the pump housing to calibrate the flow control assembly.
Other aspects and advantages of the present invention will become apparent upon consideration of the following drawings and detailed description.
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patent: 5462115
Higbee Joel E.
Sprenger Henry K.
Telly Walter P.
Freay Charles G.
Milton Roy Company
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