Electrically heated seat control system

Claim 2

Apparatus for heating a motor vehicle seat by energizing a resistive heating element embedded within the motor vehicle seat comprising energizing means coupled to a motor vehicle ignition switch to couple a voltage across the heating element; sensing means to sense a temperature of said heating element and generate a control signal output related to said temperature; switch means coupled to the control signal output to control current through said heating element; and failure detection means coupled to said energizing means for de-energizing said heating element in the event said failure detection means senses a malfunction in the apparatus.

Claim 3

The apparatus of Claim 1 where the failure detection means comprises means for detecting excessive current through the heating element.

Claim 4

The apparatus of Claim 1 where the energizing means comprises a relay having a coil and a contact that closes when the coil is energized, and where the failure detection means de-activates the coil in the event of a malfunction in the apparatus.

Claim 5

The apparatus of Claim 1 where the switch means comprises a gate controlled transistor which turns on to carry current passing through said heating element.

Claim 6

The apparatus of Claim 1 additionally comprising delay means coupled between the sensing means and the switch means for imposing a time delay between a change in the control signal output from said sensing means and receipt of the change in the control signal output by the switch means.

Claim 7

The apparatus of Claim 1 additionally comprising means for suppressing spurious transient signals originating at the energizing means from reaching the sensing means, the switch means, and the failure detection means.

Claim 10

The method of Claim 7 where the temperature sensing step includes the steps of sensing a voltage at the juncture between the heating element and impedance device and generating a control signal based on said voltage to energize a switch to bypass the impedance device and wherein the monitoring step additionally comprises the step of monitoring the control signal and comparing said control signal with a signal corresponding to the voltage at the juncture to sense a short circuit across the heating element or the switch.

Claim 11

The method of Claim 8 wherein the step of applying an energization signal is accomplished by closing a relay contact when a vehicle ignition switch is closed and said relay contact is opened if a short is sensed across the heating element or the switch.

Claim 12

A heated seat control for energizing a resistive heating element embedded within a vehicle seat comprising: a) an energization circuit coupled to an ignition signal of a vehicle, said energization circuit including a relay coil, relay contact, and energizing transistor for energizing the relay coil to couple the ignition signal to the heating element through the relay contact; b) temperature sensing means including a comparator circuit for comparing a temperature signal from the heating element with an operator adjusted refer­ence signal; c) a switching transistor having a control input coupled to an output from the comparator to adjust current passing through the heating element and control the temperature of the heating element; and d) fault sensing logic circuitry coupled to the heating element and the switching transistor to monitor energizing voltages, said fault sensing logic circuitry having a logic output coupled to said energizing transistor to turn off said energizing transistor and open the relay contact in the event said energizing voltages indicate a fault condition.

Claim 13

A heated seat control for energizing a resistive heating element embedded within a vehicle seat comprising: a) an energization circuit coupled to an ignition signal of a vehicle, said energization circuit including a relay coil, relay contact, and energizing transistor for energizing the relay coil to couple the ignition signal to the heating element through the relay contact; b) temperature sensing means including a comparator circuit for comparing a temperature signal from the heating element with an operator adjusted refer­ence signal; c) a switching transistor having a control input coupled to an output from the comparator to adjust current passing through the heating element and control the temperature of the heating element; and d) fault sensing logic circuitry coupled to the heating element and the switching transistor to monitor energizing voltages, said fault sensing logic circuitry having a logic output coupled to said energizing transistor to turn off said energizing transistor and open the relay contact in the event said energizing voltages indicate a fault condition.

Claim 14

The heated seat control of Claim 10 wherein the fault sensing logic comprises a logic gate with first and second inputs, said first input electrically coupled to the control input of said switching transistor and said second input coupled to said heating element, said logic gate producing a fault signal at said logic output when the two inputs are both above or both below a logic gate threshold level.