LIQUID LEVEL CONTROL SYSTEM

• US 3,787,733 A
• Filed: 01/05/1973
• Issued: 01/22/1974
• Est. Priority Date: 01/05/1973
• Status: Expired due to Term

• Current Assignee: Tony Peters
• Original Assignee: Tony Peters
• Inventors: Peters, Tony
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Smith, William J.
• Application Number:
  US05/302,947
• Time in Patent Office: 382 Days
• Field of Search: 307/118 73/29R 340/244C,245,246 317/DIG.1,DIG.3 137/392
• US Class Current: 307/118
• CPC Class Codes: G05D 9/12 characterised by the use of electric means
• CPC Class Codes: Y10T 137/7306 Electrical characteristic sensing

Abstract

A liquid level control system for a sump pit utilizing solid state circuitry and being operable over a wide range of liquid resistances. A pair of electrodes are disposed in the sump pit at different depths. When the liquid rises to the height of the upper-most electrode, a transistor switch is triggered which energizes two relays connected in the collector circuit of the transistor. The energization of one of the relays activates a sump pump motor for emptying liquid from the sump pit and energization of the other relay connects the lower-most electrode to the circuitry so that transistor switch does not turn off until the liquid is emptied to a level beneath the lower-most electrode.

Claims

1. A system for controlling the level of a liquid in an enclosure wherein the liquid may vary in conductivity comprising first and second electrodes inserted in said enclosure at different depths, said first electrode being positioned above said second electrode, means including motor means for emptying liquid from said enclosure, first relay means for activating said motor means when energized, electronic switch means connected in circuit relationship with said first relay means for energizing said first relay means to empty said enclosure when turned on, means for turning said switch means on when the liquid in said enclosure is in electrical contact or is electrically connected to said first electrode and for turning said switch means off when said liquid is not electrically connected to said first electrode, and second relay means in circuit relationship with said electronic switch means for connecting said second electrode to said first electrode when said electronic switch means in turned on so that the switch means is not turned off until said liquid falls beneath the level of said second electrode.

2. The system of claim 1 wherein said electronic switch means is a transistor having a base-emitter junction and wherein said means for turning said switch means on includes a resistor and a capacitor connected across said base-emitter junction.

3. The system of claim 2 wherein said motor means is connected to a power source means through a triac having a gate circuit including said first relay means, said gate circuit being activated to turn said triac on and provide said motor means with electrical power when said first relay means is energized.

4. The system of claim 3 wherein said power source means comprises an alternating current power source means.

5. A system for controlling the level of a liquid in an enclosure wherein the liquid may vary in conductivity comprising first and second electrodes inserted in said enclosure at different depths, means including motor means for emptying liquid from said enclosure, first relay means for activating said motor means when energized, electronic switch means connected in circuit relationship with said first relay means for energizing said first relay means when turned on, a normally open ciRcuit loop including said liquid in said enclosure and said first electrode for turning said electronic switch means on when said liquid contacts said first electrode and closes said circuit loop, and second relay means in circuit relationship with said electronic switch means for connecting said second electrode at said different depth to said circuit loop when energized by the turning on of said electronic switch means, said first electrode being inserted in said enclosure above said second electrode, said circuit loop further including a direct current source of electrical power, said electronic switch means being a transistor having a base-emitter junction and said circuit loop further including a resistor and capacitor connected across said base-emitter junction, said capacitor being charged from said source of electrical power when said circuit is closed to turn said transistor on, said motor means being connected to a power source through a triac having a gate circuit including said first relay means, said gate circuit being activated to turn said triac on and provide said motor means with electrical power when said first relay means is energized, and said first and second relay means being in series circuit relationship with each other and being located in the collector circuit of said transistor.