Pressure responsive motor control circuit for vehicle leveling

Claim 2

A pressure responsive motor control circuit comprising: means including a relay operated switch for energizing an electric motor, said relay operated switch having a coil, means including a pressure responsive start switch for connecting said coil to a power source to energize said motor, said pressure responsive switch responsive to a first pressure to start the motor and responsive to a reduced pressure to initiate a time delayed stop of the motor, means including a resistor and said relay operated switch to hold said coil energized following motor start and while the pressure switch senses the reduced pressure, normally open switch means shunting said coil, timer means responsive to said pressure responsive start switch to condition said normally open switch means to shunt said coil and open said relay operated switch to de-energize said motor a predetermined period after said pressure responsive start switch disconnects said coil from the power source.

Claim 3

In the combination of claim 1 normally open switch means including a three terminal solid-state device having its anode, cathode terminals connected in shunt relationship to the coil of said relay operated switch, a terminal on said device responsive to a predetermined control signal pulse to cause said device to be conductive between the anode and cathode terminals so as to shunt said relay switch coil and thereby open said first circuit means to de-energize said electric motor, said timer means including a resistance, capacitor circuit with a predetermined time delay before said signal pulse occurs on said terminal.

Claim 4

A pressure responsive motor control circuit comprising: means including a relay operated switch for energizing an electric motor, said relay operated switch having a coil, means including a pressure responsive start switch for connecting said coil to a power source to condition said relay switch to energize said motor, said pressure responsive switch having a pair of contacts and a diaphragm for moving one of said contacts to a closed and opened position, means for directing a first pressure to said diaphragm to move said contacts closed to start the motor, means including said diaphragm responding to a reduced pressure in said conduit means to open said contacts, means including a compressor operated by said motor to pump down said conduit means to a pressure less than the reduced pressure to cause said diaphragm to be biased in a direction to further separate said contacts against closure, means including a resistor and said relay operated switch to hold said coil energized following motor start and when said pressure responsive switch senses said reduced pressure, normally open switch means shunting said coil, timer means operable when said pressure responsive start switch senses said reduced pressure to initiate a delay period following which said normally open switch means is conditioned to shunt said coil and open said relay operated switch to bypass said holding circuit means and to opeN said energization circuit means thereby to de-energize said motor a predetermined period after said pressure responsive start switch senses said reduced pressure.

Claim 5

A pressure responsive motor control circuit comprising: means including a relay operated switch for energizing an electric motor, said relay operated switch having a coil, means including a pressure responsive start switch for connecting said coil to a power source to condition said relay switch to energize said motor, said pressure responsive switch having a pair of contacts and a diaphragm for moving one of said contacts to a closed and opened position, means for directing a first pressure to said diaphragm to move said contacts closed to start the motor, means including said diaphragm responding to a reduced pressure in said conduit means to open said contacts, means including a compressor operated by said motor to pump down said conduit means to a pressure less than the reduced pressure to cause said diaphragm to be biased in a direction to further separate said contacts against closure, means including a resistor and said relay operated switch to hold said coil energized following motor start and when said pressure responsive switch senses said reduced pressure, normally open switch means shunting said coil, timer means operable when said pressure responsive start switch senses said reduced pressure to initiate a delay period following which said normally open switch means is conditioned to shunt said coil and open said relay operated switch to bypass said holding circuit means and to opeN said energization circuit means thereby to de-energize said motor a predetermined period after said pressure responsive start switch senses said reduced pressure.

Claim 6

In the combination of claim 3, said normally open switch means including a three terminal solid-state device having its anode, cathode terminals connected in shunt relationship to the coil of said relay operated switch, said timer means including a resistance and capacitor circuit charged for a predetermined time delay when said pressure switch senses reduced pressure to produce a signal pulse following the time delay, a terminal on said device responsive to said signal pulse from said timer means to cause said device to be conductive between the anode and cathode terminals so as to shunt said relay switch coil and thereby cause it to be conditioned to open said first circuit means to de-energize said electric motor.