Engine heater monitor and control system

Claim 2

An engine heater monitor system comprising: a unitary housing for said system adapted for mounting on a motor vehicle; an electric power circuit including first coupling means for connecting to an electric energy supply, second coupling means for connecting to an engine heater means, and a power circuit connection between said coupling means including current responsive switching means having a solenoid serially connected between said first and second coupling means and responsive to predetermined current level approximating the rated current of said heater means for actuating associated switching circuits; and indicator means energized from said supply through said switching circuits for indicating both conditions of current level above and below said predetermined level; said indicator means comprising a first lamp responsive to electric energy from said supply applied to said first coupling means through normally closed contacts of said switching circuits, a second lamp responsive to electrical energy from said supply applied to said first coupling means through normally open contacts of said switching circuits, whereby the conditions of energized but not supplying heater current, energized and supplying heater current and de-energized are visually indicated for remote observation.

Claim 3

An engine heater monitor unit comprising: a unitary housing for said said unit adapted to be mounted on a motor vehicle; a power plug for connecting to a line voltage source; a relay having normally open and normally closed switching contacts and a current coil for actuating said contacts at a predetermined current level; a heater plug for connecting to an engine heater unit; a line circuit connecting said power plug to said heater plug with said current coil serially connected in one line; first and second visually dissimilar indicator lamps; a circuit connecting line voltage from said power plug to said first indicator lamp through said normally closed contacts; a circuit connecting line voltage from said power plug to said second indicator lamp through said normally open contacts; a third indicator lamp visually distinguishable from said first and second lamps and having rated current substantially below the rated current of a monitored engine heater; and a circuit for connecting said third indicator lamp across thermostatically controlled power contacts associated with said engine heater which said power contacts are in series circuit with said current coil; said current coil being adapted to establish said predetermined current level somewhat less than said rated current for said monitored engine heater but not low enough to actuate said relay for rated current of said third indicator lamp; whereby the conditions of energized but not supplying heater current, energized and supplying heater current, energized on stand-by waiting for thermostat demand and de-energized are visibly indicated for remote observation.

Claim 4

An engine heater monitor unit comprising: a unitary housing for said said unit adapted to be mounted on a motor vehicle; a power plug for connecting to a line voltage source; a relay having normally open and normally closed switching contacts and a current coil for actuating said contacts at a predetermined current level; a heater plug for connecting to an engine heater unit; a line circuit connecting said power plug to said heater plug with said current coil serially connected in one line; first and second visually dissimilar indicator lamps; a circuit connecting line voltage from said power plug to said first indicator lamp through said normally closed contacts; a circuit connecting line voltage from said power plug to said second indicator lamp through said normally open contacts; a third indicator lamp visually distinguishable from said first and second lamps and having rated current substantially below the rated current of a monitored engine heater; and a circuit for connecting said third indicator lamp across thermostatically controlled power contacts associated with said engine heater which said power contacts are in series circuit with said current coil; said current coil being adapted to establish said predetermined current level somewhat less than said rated current for said monitored engine heater but not low enough to actuate said relay for rated current of said third indicator lamp; whereby the conditions of energized but not supplying heater current, energized and supplying heater current, energized on stand-by waiting for thermostat demand and de-energized are visibly indicated for remote observation.