Switch for controlling the motor of a piston pump

Details Switch for controlling the motor of a piston pump Switch for controlling the motor of a piston pump

2000-06-22

2002-07-16

Freay, Charles G. (Department: 3746)

Pumps

Condition responsive control of pump drive motor

By control of electric or magnetic drive motor

C417S053000, C417S307000, C417S308000, C200S08200C, C200S08200C, C073S745000

Reexamination Certificate

active

06419456

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a pump. More particularly, the present invention relates to a liquid pump useful for pumping liquid paints, stains, and the like.
BACKGROUND OF THE INVENTION
There is a need for inexpensive yet reliable and effective pumps for pumping fluids, including paint, stains, and the like to a dispenser of such fluids. Such pumps are primarily intended for use in a household environment, as distinct from a commercial environment. Accordingly, the emphasis is on cost containment, while having the requisite durability for the environment of the intended use. The pumps should be readily throttleable for use with very high flow rates and high pressures and for use with relatively low flow rates and low pressures. An example of high flow rates and high pressures would be the use of a spray gun dispenser with relatively viscous paint. Dispensing a relatively low viscosity stain through a spray gun typically requires significantly lower pressures, but the flow rate is high. A further type of dispensation is by means of a roller that is supplied with paint from the pump. Such means of dispensation require a relatively low fluid volume at relatively low fluid pressure for delivery of the viscous paint. There is a need in the industry for a pump that is throttleable to accommodate all the exemplary types of dispensation listed above and other types of dispensation as well.
There is a further need in the industry to enhance the reparability of such pumps. A potential problem area with such pumps is the pump assembly. If there is difficulty with the pump assembly, it is desirable that the pump assembly be readily removable from the housing in which it is disposed for repair or replacement. In existing pumps, the pump assembly is not readily removable.
There is a further need to simplify as much as possible the construction of the pump. A reduction in the number of component parts is one path to such simplification. One area in which such simplification is desirable is in the area of the pressure switch assembly. In the past, such assemblies were complex and required rather lengthy plumbing between the pump assembly and the position on the side of the motor housing where the pressure switch assembly was mounted. Another area of needed simplification is that, in the existing pumps, the main gear housing and the pump assembly housing are formed as two separate components. A desired simplification of the structure of the pump would be to combine the main gear housing and the pump housing into a single component. A further area of needed simplification is in the number of cast components as distinct from more costly screw machined parts.
SUMMARY OF THE INVENTION
The present invention substantially meets the aforementioned needs of the industry. Simplification of the piston pump of the present invention is evident in a single main housing that incorporates a housing for both the pump assembly and the pump drive assembly. Additionally, the pump housing is machinable from a single direction to simplify production. A further benefit of this is that it allows the pump assembly installed in the pump housing to be fully serviceable from that same direction.
Additionally, the pressure switch assembly of the present invention is greatly simplified in construction with respect to the pressure switch assemblies of the prior art. And, the pressure switch assembly of the present invention allows for greatly varying the flow rate and flow pressure of the liquid pumped by the piston pump of the present invention, unlike pressure switch assemblies of the prior art. The pressure switch assembly advantageously has a certain compliance built in to accommodate an over pressure condition without damage to any pressure switch assembly components.
Another area of simplicity in the design of the piston pump of the present invention is in the design of the pump assembly. The pump assembly is elongate in design and is readily extractable from the pump housing bore for repair as necessary. Further, a number of key components are now cast, where previous components performing the same function were screw machined, a significantly more costly operation.
The present invention is a fluid pump having a motor operably coupled to a pump assembly, the motor and pump assembly acting cooperatively to pressurize a fluid includes a pressure switch being in communication with the fluid under pressure and being in communication with the motor for sensing the fluid pressure and controlling the operation of the motor to maintain a selected fluid pressure. The present invention is further a method of controlling fluid pressure in a fluid pump, the fluid pressure being generated by activating a pump motor to operate a pump assembly, including the steps of:
selecting a desired fluid pressure by manual actuation of a set screw assembly;
positioning a micro switch relative to a pressure sensor assembly by means of such selection;
engaging the micro switch by means of a pressure sensor assembly at the selected fluid pressure;
sending a signal to the pump motor by means of the micro switch upon engagement by the pressure sensor assembly; and
deactivating the pump motor responsive to the signal sent from the micro switch.


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