Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Patent
1989-12-20
1992-03-03
Bertsch, Richard A.
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
417 18, F04B 4906
Patent
active
050927396
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an electronic control means, which is particularly intended to be used to control the operation of a pump.
In common use is a small electric pump, operated by a D.C. motor, the operation of the motor, and hence the flow rate of fluid supplied by the pump, being controlled by a voltage applied to the pump. In many circumstances, for example when applying a potent and expensive weedkiller to an area of land, it is important to deliver a quantity of fluid which can be accurately measured and controlled. In such circumstances, it is important to be able to supply to the pump an input signal which may be varied with the particular operating conditions, but which may be accurately maintained once set.
Moreover, in known weedkiller delivery units, the delivery device itself is a hand-held piece of equipment, used by an operator walking across the area to which the weedkiller is to be applied. In these circumstances, it is advantageous if any control means for the pump additionally forms part of the hand-held equipment, in which case it must be made small, light and robust.
According to the present invention, there is provided an electronic control means for a pump, the control means comprising:
input means, for accepting input signals, the input signals being indicative of the values of variable quantities which determine a desired fluid flow rate which, in use, is to be supplied by a pump;
an electronic memory, comprising a plurality of memory locations, each memory location corresponding to a particular combination of values of the variable quantities and containing a stored control signal corresponding to the desired fluid flow rate determined by those values; and
output means, for supplying the control signal, in use, to the pump.
In a preferred embodiment of the invention, the variable quantities, which may be input by an operator, and which determine the desired fluid flow rate, are the width of a strip of land which is to be sprayed, the volume of fluid which is to be applied to a unit area of that land, and the linear speed of the distribution means along the strip.
More specifically, the present invention provides equipment suitable for distributing a fluid over an area of land, the equipment comprising distribution means, to which fluid is supplied by a pump driven by an electric motor, the delivery rate of the fluid from the pump being a function of the operating speed of the pump, the equipment further comprising control means for controlling the operating speed of the pump, the control means comprising a memory in which are stored data representing desired delivery rates of fluid under different operating conditions of the equipment, the stored data being output when information concerning the operating conditions is supplied to the control means, and output data being supplied to the electric motor to control the operation thereof.
For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
FIG. 1 is a block diagram illustrating the known control system associated with a conventional pump;
FIG. 2 is a plot of the pump speed/flow rate characteristic of a known pump;
FIG. 3 shows, schematically, an electronic control means in accordance with an embodiment of the invention;
FIG. 4 shows, in more detail, the circuitry of the embodiment illustrated in FIG. 3;
FIG. 5 illustrates the type of equipment which may be provided with control means according to the present invention;
FIG. 6 is an enlarged perspective view of the handle of the equipment shown in FIG. 5; and
FIG. 7 is a different perspective view of the handle shown in FIG. 6.
FIG. 1 illustrates the control system which is associated with conventional pumps. A pump control 1 acts upon an input voltage VIN to cause a pump 2 to rotate at a speed proportional to the applied voltage.
FIG. 2 illustrates the characteristic of the system. Thus, increasing the speed of rotation of the motor in the pump 2 p
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Bertsch Richard A.
Nomix Manufacturing Company Limited
Scheuermann David W.
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