Control circuit for refrigeration compressor motor

Claim 2

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means operatively coupling said supply with said motor comprising means for controllably conducting current from said supply to said motor in accordance with the temperature of said medium; under-voltage sensing means operatively coupled with said motor input circuit means to sense the voltage of said supply, said under-voltage sensing means comprising means responsive to a first under-voltage condition of said supply for providing a control signal in time delayed relation to occurrence of the condition, means responsive to a second undervoltage condition of said supply for providing said control signal substantially contemporaneously with occurrence of said second condition; means responsive to said control signal for inhibiting current flow from said supply to said motor; wherein the voltage of said power supply at which said first under-voltage condition occurs has a larger magnitude than the voltage at which said second under-voltage condition occurs; wherein said motor input circuit means includes solid state electronic switching means and temperature responsive means providing switch control signals in accordance with cooling demand, said temperature responsive means being D. C. isolated from said solid state electronic switch means, said switch control signals being magnetically coupled to said solid state electronic switching means; and including photocoupler means interlocking said under-voltge sensing means with said temperature responsive means for preventing generation of said switch control signals when said control signal is given by said under-voltage sensing means.

Claim 3

In combination: a refrigeration system for providing cooling to a medium to be cooled including an A.C. refrigeration compressor motor; an A.C. supply for supplying electrical power to said motor; means operatively coupling said supply and said motor including electronic semi-conductor switch means having a triggering means, said switch means conducting current from said supply to said motor in response to application of trigger pulse signals to said triggering means; a control circuit for controlling the operation of said switch means including temperature responsive means for providing a temperature signal indicative of a need for cooling in the medium to be cooled, and an oscillator means responsive to said temperature signal for producing oscillations; a magnetic coupling means operatively coupling said oscillator means and said triggering means for applying trigger pulse signals to said triggering means in response to oscillations of said oscillator means; supply sensing means operatively coupled with said supply for providing a control signal in response to a predetermined condition of said supply; and a photoresponsive solid state semi-conductor device operatively coupling said supply sensing means and said control circuit for preventing the generation of said oscillations in response to said control signal.

Claim 4

In combination: a refrigeration system for providing cooling to a medium to be cooled including an A.C. refrigeration compressor motor; an A.C. supply for supplying electrical power to said motor; means operatively coupling said supply and said motor including electronic semi-conductor switch means having a triggering means, said switch means conducting current from said supply to said motor in response to application of trigger pulse signals to said triggering means; a control circuit for controlling the operation of said switch means including temperature responsive means for providing a temperature signal indicative of a need for cooling in the medium to be cooled, and an oscillator means responsive to said temperature signal for producing oscillations; a magnetic coupling means operatively coupling said oscillator means and said triggering means for applying trigger pulse signals to said triggering means in response to oscillations of said oscillator means; supply sensing means operatively coupled with said supply for providing a control signal in response to a predetermined condition of said supply; and a photoresponsive solid state semi-conductor device operatively coupling said supply sensing means and said control circuit for preventing the generation of said oscillations in response to said control signal.

Claim 5

The combination of claim 2 wherein said photoresponsive device comprises a phototransistor electrically connected in said oscillator means and a photodiode electrically connected in said supply sensing means.

Claim 6

The combination of claim 2 wherein the frequency of oscillations of said oscillator means is substantially greater than the frequency of the A.C. supply.

Claim 7

The combination of claim 2 wherin said supply sensing means includes means giving said control signal in time-delayed relation to the occurrence of a first under-voltage condition and means giving said control signal substantially contemporaneously with a second under-voltage condition.

Claim 8

The combination of claim 5 wherein said second undervoltage condition occurs at a supply voltage less than the supply voltage at which said first under-voltage condition occurs.

Claim 9

The combination of claim 2 including electronic timing circuit means responsive to said control signal for delaying the resumption of current to said motor for at least a given minimum delay period.

Claim 10

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means via which said electrical power supply is coupled with said motor, said input circuit means including temperature responsive circuit means for permitting current to flow from said supply to said motor when the temperature of said medium exceeds a given level; supply sensing circuit means operatively coupled with said motor input circuit means to sense the voltage of said supply, said supply sensing circuit means including pulse generating means for generating pulses so long as the voltage of said supply remains above a given minimum and detection circuit means for providing a control signal in response to the continuous absence of pulses from said pulse generating means for a predetermined time; and coupling circuit means operativey coupling said supply sensing circuit means and said motor input circuit means for inhibiting current flow from said supply to said motor in response to said control signal.

Claim 11

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means via which said electrical power supply is coupled with said motor, said input circuit means including temperature responsive circuit means for permitting current to flow from said supply to said motor when the temperature of said medium exceeds a given level; supply sensing circuit means operatively coupled with said motor input circuit means to sense the voltage of said supply, said supply sensing circuit means including pulse generating means for generating pulses so long as the voltage of said supply remains above a given minimum and detection circuit means for providing a control signal in response to the continuous absence of pulses from said pulse generating means for a predetermined time; and coupling circuit means operativey coupling said supply sensing circuit means and said motor input circuit means for inhibiting current flow from said supply to said motor in response to said control signal.

Claim 12

The combination of claim 8 wherein said electrical power supply is A.C. and said pulse generating means comprises means responsive to the peak amplitude of said A.C. for providing pulses so long as the peak amplitude remains above a given level.

Claim 13

The combination of claim 8 wherein said supply sensing circuit means includes means for generating said control signal substantially contemporaneously in response to another condition of the supply.

Claim 14

The combination of claim 10 wherein said control signal is given in response to a continuous absence of said pulses for a period of approximately several seconds.

Claim 15

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means via which said electrical power supply is coupled with said motor, said input circuit means including temperature responsive circuit means for permitting current to flow from said supply to said motor when the temperature of said medium exceeds a given level; a time delay circuit operatively coupled with said motor input circuit for providing at least a given minimum delay period between successive applications of current to said motor from said supply, said time delay circuit including a timer circuit whose timing period defines the duration of said minimum delay period; and supply sensing circuit means operatively coupled with said motor input circuit means and said timer circuit to sense the voltage of said supply and permit said timer circuit to time only if the voltage of said supply remains above a given magnitude.

Claim 16

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means via which said electrical power supply is coupled with said motor, said input circuit means including temperature responsive circuit means for permitting current to flow from said supply to said motor when the temperature of said medium exceeds a given level; a time delay circuit operatively coupled with said motor input circuit for providing at least a given minimum delay period between successive applications of current to said motor from said supply, said time delay circuit including a timer circuit whose timing period defines the duration of said minimum delay period; and supply sensing circuit means operatively coupled with said motor input circuit means and said timer circuit to sense the voltage of said supply and permit said timer circuit to time only if the voltage of said supply remains above a given magnitude.

Claim 17

The combination of claim 12 wherein the timing period of said timer circuit commences in response to termination of current flow from said supply to said motor so long as the voltage of said supply remains above said given magnitude.

Claim 18

The combination of claim 13 wherein said timer circuit includes a ramp generator and a comparator.

Claim 19

The combination of claim 13 wherein said motor input circuit means includes a solid state electronic switch means and an input of said timer is connected across said electronic switch means to sense the voltage rise in response to termination of current through the solid state electronic switch means.

Claim 20

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means comprising solid state switch means connecting said motor and said supply; temperature responsive circuit means for providing triggering signals to said solid state switch means when the temperature of said medium exceeds a desired level, said solid state switch means conducting current from said supply to said motor in response to said triggering signals; timing interlock circuit means for interlocking said motor input circuit means with said temperature responsive circuit means such that at least a given minimum time delay occurs between successive applications of current from said supply to said motor, said timing interlock circuit means comprising a comparator circuit having a pair of inputs and an output, means operatively coupling said motor input circuit means with one of said comparator inputs such that in response to termination of current flow from said supply to said motor a reference signal is supplied to said one comparator input causing the output of said comparator to assume a first state, a ramp generator circuit operatively coupled with the other input of said comparator for supplying a ramp waveform thereto, means operatively coupling said ramp generator circuit with said motor input circuit means such that generation of said ramp waveform is initiated in response to termination of current flow from said supply to said motor, the output of said comparator switching from the first state to a second state when the ramp attains a certain relation to the reference signal applied to said one comparator input, and means operatively coupling said comparator circuit with said temperature responsive circuit means such that when the output of said comparator circuit is in said first state the transmission of triggering pulses from said temperature responsive circuit means to said solid state switch means is inhibited and when the output of said comparator circuit is in said second state the transmission of triggering pulses from said temperature responsive circuit means to said solid state switch means is permitted.

Claim 21

In combination: a refrigeration system for providing cooling to a medium to be cooled including an electrical compressor motor; an electrical power supply; motor input circuit means comprising solid state switch means connecting said motor and said supply; temperature responsive circuit means for providing triggering signals to said solid state switch means when the temperature of said medium exceeds a desired level, said solid state switch means conducting current from said supply to said motor in response to said triggering signals; timing interlock circuit means for interlocking said motor input circuit means with said temperature responsive circuit means such that at least a given minimum time delay occurs between successive applications of current from said supply to said motor, said timing interlock circuit means comprising a comparator circuit having a pair of inputs and an output, means operatively coupling said motor input circuit means with one of said comparator inputs such that in response to termination of current flow from said supply to said motor a reference signal is supplied to said one comparator input causing the output of said comparator to assume a first state, a ramp generator circuit operatively coupled with the other input of said comparator for supplying a ramp waveform thereto, means operatively coupling said ramp generator circuit with said motor input circuit means such that generation of said ramp waveform is initiated in response to termination of current flow from said supply to said motor, the output of said comparator switching from the first state to a second state when the ramp attains a certain relation to the reference signal applied to said one comparator input, and means operatively coupling said comparator circuit with said temperature responsive circuit means such that when the output of said comparator circuit is in said first state the transmission of triggering pulses from said temperature responsive circuit means to said solid state switch means is inhibited and when the output of said comparator circuit is in said second state the transmission of triggering pulses from said temperature responsive circuit means to said solid state switch means is permitted.

Claim 22

The combination of claim 16 wherein said timing interlock means is connected across said solid state switch means to supply said reference signal.

Claim 23

The combination of claim 16 including under-voltage sensing means responsive to the voltage of said electrical power supply for preventing operation of said ramp generator whenever the supply voltage drops below a given magnitude.

Claim 24

In a refrigeration system for supplying cooling to a medium, said system having an electrical compressor motor which is energizeed from an electrical power supply whose voltage magnitude is subject to variation, the combination comprising: a motor input circuit means comprising solid state switch means connecting said motor and said supply; temperature responsive circuit means operatively coupled with said solid state switch means to initiate conduction thereof when the temperature of the medium exceeds a given level; supply sensing circuit means operatively coupled with said motor input circuit means to sense the voltage of said supply and to supply a timer stop signal when the voltage of said supply drop below a given magnitude; switch sensing circuit means operativey coupled with said motor input circuit means to sense conduction of said solid state switch means and to supply a timer start signal when nonconduction of said solid state switch means is sensed; and a timer circuit means comprising a run input circuit operatively coupled with said switch sensing circuit means, a stop input circuit operatively coupled with said supply sensing circuit means, and an output circuit operatively coupled with said motor input circuit means; said timer circuit means further comprising an electronic timer circuit which is tripped by said timer start signal but which is prevented from timing out by said timer stop signal; said timer circuit means providing at its output circuit a signal which inhibits conduction of said solid state switch means when said timer circuit is tripped.

Claim 25

In a refrigeration system for supplying cooling to a medium, said system having an electrical compressor motor which is energizeed from an electrical power supply whose voltage magnitude is subject to variation, the combination comprising: a motor input circuit means comprising solid state switch means connecting said motor and said supply; temperature responsive circuit means operatively coupled with said solid state switch means to initiate conduction thereof when the temperature of the medium exceeds a given level; supply sensing circuit means operatively coupled with said motor input circuit means to sense the voltage of said supply and to supply a timer stop signal when the voltage of said supply drop below a given magnitude; switch sensing circuit means operativey coupled with said motor input circuit means to sense conduction of said solid state switch means and to supply a timer start signal when nonconduction of said solid state switch means is sensed; and a timer circuit means comprising a run input circuit operatively coupled with said switch sensing circuit means, a stop input circuit operatively coupled with said supply sensing circuit means, and an output circuit operatively coupled with said motor input circuit means; said timer circuit means further comprising an electronic timer circuit which is tripped by said timer start signal but which is prevented from timing out by said timer stop signal; said timer circuit means providing at its output circuit a signal which inhibits conduction of said solid state switch means when said timer circuit is tripped.