Liquid level control

Claim 2

A liquid level control device comprising a. upper and lower sensors positioned in vertically spaced relation in a fluid reservoir and individually operable between conductive and non-conductive states in response to the level of fluid in said reservoir, b. a motor control device operative between ''''on'''' and ''''off'''' states in response to a current of predetermined magnitude, c. a source of electric operating potential, d. a switching element having electrode means for coupling the switching element electrically between said motor control device and said source and further having a control electrode, said switching element being operable between conductive and non-conductive states in response to the presence and absence, respectively, of a control signal between said electrode means and said control electrode, e. first biasing circuit means consisting of passive circuit elements coupled to said electrode means and coupled to said control electrode through said lower sensor for applying a first control signal between said electrode means and said control electrode when said lower sensor changes between conductive and non-conductive states, f. second biasing circuit means consisting of passive circuit elements coupled to said electrode means and coupled to said control electrode through the upper sensor for applying a second control signal between said control electrode and electrode means when said upper sensor changes between conductive and non-conductive states to turn said switching element ''''on'''', said switching element remaining ''''on'''' until said lower sensor changes back to its original state.

Claim 3

The device of claim 1 wherein said switching element is a triac, said source being an alternating current source, said first control signal being an alternating current signal shifted in phase with respect to said source current.

Claim 4

The device of claim 2 wherein said control gate is connected to ground.

Claim 5

The device of claim 1 wherein said first biasing circuit includes a resistor and a capacitor connected electrically in parallel between switching element and said lower sensor.

Claim 6

The device of claim 4 wherein said biasing circuit includes a voltage divider having a tap between its ends, said voltage divider being connected electrically in parallel with said switching element, said tap being connected to said upper sensor.

Claim 7

The device of claim 4 wherein said second biasing circuit includes a potentiometer connected electrically in parallel with said switching element, said potentiometer including a wiper connected to said upper sensor.

Claim 8

The device of claim 1 wherein said upper and lower sensors includes upper and lower electrodes and a common electrode, said upper and lower electrodes being disposed in spaced-apart relationship to said common electrode, said common electrode being connected to ground.

Claim 9

The device of claim 3 further including a noise suppressing capacitor connected between one element of said triac and said control gate.

Claim 10

The device of claim 7 wherein said motor control device is an alternating current relay having a relay coil connected electrically in series with the load circuit of said triac.

Claim 11

The device of claim 2 wherein said source of operating potential includes a step-down transformer having a pair of output terminals, said triac including first and second electrodes, one of said triac electrodes being connected to one of said transformer output terminals, said motor control device including an alternating current relay having an operating coil connected eleCtrically in series between the other of said triac electrodes and the other of said transformer output terminals, said first biasing circuit including a resistor and capacitor connected electrically in parallel between said other of said transformer terminals and said lower sensor, said second biasing circuit including a voltage divider connected electrically in parallel with said triac and having a voltage tap connected to said upper sensor, said upper and lower sensors including upper and lower sensor electrodes, respectively, and a common electrode disposed in spaced-apart relationship thereto, said common electrode being connected to said control gate, said control gate being connected to ground, and a noise suppressing capacitor connected between said other triac electrode and said control gate.

Claim 14

The device of claim 11 wherein said control gate is grounded, said first biasing circuit means being a resistive circuit, said second biasing circuit means including a reactive element.

Claim 15

A liquid level control device comprising a. upper and lower sensors positioned in vertically spaced relation in a fluid reservoir and individually operable between conductive and non-conductive states in response to the level of fluid in said reservoir, b. a motor control device operative between ''''on'''' and ''''off'''' states in response to a current of predetermined magnitude, c. a source of alternating current operating potential having two terminals, d. a bi-directional conductive switching element having two coupling electrodes, one of said coupling electrodes being connected to one terminal of said source of alternating current and the other of said coupling electrodes being connected to said motor control device, said motor control device being connected to the other terminal of said source of alternating current operating potential, e. said bi-directional conductive switching element having a control electrode, said switching element being operable between conductive and non-conductive states in response to the presence and absence, respectively, of a control signal between said control electrode and said coupling electrodes, f. first biasing circuit means connected to said control electrode through one of said sensors for applying a firSt alternating current control signal between said coupling electrodes and said control electrode, when said one sensor changes between a conductive and non-conductive state to cause said switching element to become conductive, g. second biasing circuit means connected to said control electrode through the other of said sensors for applying a second alternating current control signal between one of said coupling electrodes and said control electrode when said other sensor changes between a conductive and non-conductive state when said switching element is rendered conductive by said first biasing circuit, said switching element remaining conductive until said second sensor changes back to its original state.

Claim 16

A liquid level control device comprising a. upper and lower sensors positioned in vertically spaced relation in a fluid reservoir and individually operable between conductive and non-conductive states in response to the level of fluid in said reservoir, b. a motor control device operative between ''''on'''' and ''''off'''' states in response to a current of predetermined magnitude, c. a source of alternating current operating potential having two terminals, d. a bi-directional conductive switching element having two coupling electrodes, one of said coupling electrodes being connected to one terminal of said source of alternating current and the other of said coupling electrodes being connected to said motor control device, said motor control device being connected to the other terminal of said source of alternating current operating potential, e. said bi-directional conductive switching element having a control electrode, said switching element being operable between conductive and non-conductive states in response to the presence and absence, respectively, of a control signal between said control electrode and said coupling electrodes, f. first biasing circuit means connected to said control electrode through one of said sensors for applying a firSt alternating current control signal between said coupling electrodes and said control electrode, when said one sensor changes between a conductive and non-conductive state to cause said switching element to become conductive, g. second biasing circuit means connected to said control electrode through the other of said sensors for applying a second alternating current control signal between one of said coupling electrodes and said control electrode when said other sensor changes between a conductive and non-conductive state when said switching element is rendered conductive by said first biasing circuit, said switching element remaining conductive until said second sensor changes back to its original state.

Claim 17

A liquid level control device for controlling the liquid level in a liquid container comprising first and second sensor means for sensing the level of the liquid in the container and being individually operable between conductive and non-conductive states in response to liquid levels corresponding to said first and second means position in the container, respectively, means for altering said liquid level from one to the other of said liquid levels, current responsive means for controlling operation of said altering means between ''''on'''' and ''''off'''' conditions, a solid-state alternating current switch having a control gate and being operable between conductive and non-conductive states in response to the presence and absence of a control signal between said switch and said control gate, respectively, for selectively applying current to said current responsive means, first biasing circuit means coupled to said switch and to said control gate through said first sensor for applying a first control signal between said switch and said control gate when said first sensor is conductive, and second biasing circuit means coupled to said switch and to said control gate through said second sensor for generating and applying a second control signal between said gate and said switch when said second sensor is conductive and said solid-state current switch is conductive, said switch including high and low electrodes, said first biasing circuit means generating a first gating signal of sufficient magnitude to render said switch conductive, said second biasing circuit means generating a second gating signal, said second gating signal being an alternating current signal shifted in phase with respect to the alternating current flowing through said high and low electrodes.

Claim 18

A liquid level control device for controlling the liquid level in a liquid container comprising first and second sensor means for sensing the level of the liquid in the container and being individually operable between conductive and non-conductive states in response to liquid levels corresponding to said first and second means position in the container, respectively, means for altering said liquid level from one to the other of said liquid levels, current responsive means for controlling operation of said altering means between ''''on'''' and ''''off'''' conditions, a solid-state alternating current switch having a control gate and being operable between conductive and non-conductive states in response to the presence and absence of a control signal between said switch and said control gate, respectively, for selectively applying current to said current responsive means, first biasing circuit means coupled to said switch and to said control gate through said first sensor for applying a first control signal between said switch and said control gate when said first sensor is conductive, and second biasing circuit means coupled to said switch and to said control gate through said second sensor for generating and applying a second control signal between said gate and said switch when said second sensor is conductive and said solid-state current switch is conductive, said switch including high and low electrodes, said first biasing circuit means generating a first gating signal of sufficient magnitude to render said switch conductive, said second biasing circuit means generating a second gating signal, said second gating signal being an alternating current signal shifted in phase with respect to the alternating current flowing through said high and low electrodes.

Claim 19

The device of claim 14 wherein said control gate is grounded, said first biasing circuit means being a resistive circuit, said second biasing circuit means including a reactive element.