Refrigeration apparatus control

Claim 2

A refrigeration apparatus comprising a refrigerant compressor; an air-cooled refrigerant condenser; refrigerant throttling means; and a refrigerant evaporator respectively serially connected in a closed refrigerant circuit wherein that portion of said refrigerant circuit extending from said compressor through said condenser to said throttling means is the high-pressure side; a fan disposed to pass cooling air over said refrigerant condenser; an electric fan motor drivingly connected to said fan; an alternating-current power source for said motor, a gated semiconductor switch; a first electric circuit means serially connecting said alternating-current power source, said gated semiconductor switch and said electric fan motor; a fluid pressure-electrical resistive transducer; means connecting said transducer to said high-pressure side of said refrigeration system to respond to the refrigerant pressure therein; and second electric circuit means including said electrical resistive transducer, said alternating current power source, and the gate of said gated semiconductor switch connected for controlling said gate in response to the pressure at said transducer.

Claim 3

The apparatus as defined in claim 1 wherein said transducer includes a piezoresistive component.

Claim 4

The apparatus as defined by claim 2 wherein said piezoresistive component is a semiconductor.

Claim 5

The apparatus as defined by claim 3 wherein said semiconductor is a crystalline element.

Claim 6

The apparatus as defined by claim 1 wherein said gated semiconductor switch is a symmetrical gated switch and said second electric circuit means includes a directional diode switch in series with the gate of said symmetrical gated switch.

Claim 7

A refrigeration apparatus comprising: a refrigerant compressor; an air-cooled refrigeration condenser, refrigerant throttling means; and a refrigerant evaporator respectively serially connected in a cooled refrigerant circuit wherein that portion of said refrigerant circuit extending from said compressor through said condenser to said throttling means is the high-pressure side; a fan disposed to pass cooling air over said refrigerant condenser; a first electric motor drivingly connected to said fan; an alternating-current power source; a first electric circuit for said electric motor; a second electric circuit for said second electric motor; control means connected to said power source for cyclically energizing said first and second circuits in response to the load on said refrigeration apparatus; protector means for said pressure in said high-pressure side; means for operating said fan to maintain the refrigerant pressure in said high-pressure side below said abnormally high refrigerant pressure immediately following energization of said first circuit and above a predetermined minimum pressure during the run cycle of said refrigeration apparatus; said last-mentioned means including a pressure-electrical transducer responsive to variations in refrigerant pressure of said high-pressure side, and a gated semiconductor switch in said second circuit connected for varying the current to said second motor and thus the speed of said fan in response to the electrical side of said pressure-electrical transducer.

Claim 8

A refrigeration apparatus comprising: a refrigerant compressor; an air-cooled refrigeration condenser, refrigerant throttling means; and a refrigerant evaporator respectively serially connected in a cooled refrigerant circuit wherein that portion of said refrigerant circuit extending from said compressor through said condenser to said throttling means is the high-pressure side; a fan disposed to pass cooling air over said refrigerant condenser; a first electric motor drivingly connected to said fan; an alternating-current power source; a first electric circuit for said electric motor; a second electric circuit for said second electric motor; control means connected to said power source for cyclically energizing said first and second circuits in response to the load on said refrigeration apparatus; protector means for said pressure in said high-pressure side; means for operating said fan to maintain the refrigerant pressure in said high-pressure side below said abnormally high refrigerant pressure immediately following energization of said first circuit and above a predetermined minimum pressure during the run cycle of said refrigeration apparatus; said last-mentioned means including a pressure-electrical transducer responsive to variations in refrigerant pressure of said high-pressure side, and a gated semiconductor switch in said second circuit connected for varying the current to said second motor and thus the speed of said fan in response to the electrical side of said pressure-electrical transducer.

Claim 9

In a refrigeration system, a condenser, means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and thereby condense the refrigerant circulAting therethrough, an electric motor for driving said fan, and control means including an element capable of directly sensing the head pressure in said refrigeration system and having an electrical output with a magnitude proportional to the sensed pressure, switch means connected in series with the fan motor and source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, and cyclically operating switch-controlling circuit means for opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle of said circuit means as the magnitude of the output of the sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes to prevent the pressure in the system from falling below a predetermined minimum.

Claim 10

In a refrigeration system, a condenser, means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and thereby condense the refrigerant circulAting therethrough, an electric motor for driving said fan, and control means including an element capable of directly sensing the head pressure in said refrigeration system and having an electrical output with a magnitude proportional to the sensed pressure, switch means connected in series with the fan motor and source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, and cyclically operating switch-controlling circuit means for opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle of said circuit means as the magnitude of the output of the sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes to prevent the pressure in the system from falling below a predetermined minimum.

Claim 11

In a refrigeration system, a condenser means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and whereby condense the refrigerant circulating therethrough, an electric motor for driving said fan, and control means for varying the speed of said motor and thereby the fan speed as the head pressure changes in said system to prevent the pressure from falling below a predetermined minimum during operation of said system, said control means including an element capable of directly sensing the head pressure in said refrigeration system, switch means connected in series with the fan motor and a source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, and switch-controlling circuit means for alternatively opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle thereof as the pressure sensed by said sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes.

Claim 12

In a refrigeration system, a condenser means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and whereby condense the refrigerant circulating therethrough, an electric motor for driving said fan, and control means for varying the speed of said motor and thereby the fan speed as the head pressure changes in said system to prevent the pressure from falling below a predetermined minimum during operation of said system, said control means including an element capable of directly sensing the head pressure in said refrigeration system, switch means connected in series with the fan motor and a source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, and switch-controlling circuit means for alternatively opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle thereof as the pressure sensed by said sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes.

Claim 13

The combination of an electric fan motor and control means for regulating the speed of the fan motor as to vary said speed in accord with changes in the pressure of a specified body of fluid, said control means including switch means adapted to connect the fan motor in series with a source of operating voltage, whereby said fan motor is connected across said source of operating voltage and thereby energized when said switch means is closed and cyclically operating switch-controlling circuit means including a sensing element directly responsive to pressure for opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle of said circuit means as the pressure sensed by said sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes.

Claim 14

The combination of an electric fan motor and control means for regulating the speed of the fan motor as to vary said speed in accord with changes in the pressure of a specified body of fluid, said control means including switch means adapted to connect the fan motor in series with a source of operating voltage, whereby said fan motor is connected across said source of operating voltage and thereby energized when said switch means is closed and cyclically operating switch-controlling circuit means including a sensing element directly responsive to pressure for opening and closing said switch means and for varying the duration of the period for which said switch means is closed in each operating cycle of said circuit means as the pressure sensed by said sensing element varies, whereby the speed of the fan motor is varied as the sensed pressure changes.

Claim 15

In a refrigeration system, a condenser, means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and thereby condense the refrigerant circulating therethrough, an electric motor for driving said fan, and control means including a pressure-responsive element capable of directly sensing the head pressure in said refrigeration system for varying the speed of said fan and the head pressure changes to prevent pressure from falling below a predetermined minimum during operation of said system, switch means connected between the fan motor and a source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, a source of control voltage, and cyclically operating circuit means connected between said source of control voltage and said switch means for opening and closing said switch means, said circuit means including means for varying the duration of the period for which said switch means is closed In each operating cycle of said circuit means as the control voltage applied to said circuit means is varied, said pressure-responsive element including a variable resistor connected between said control voltage source and said circuit means and means for varying the resistance of said resistor and therefore the control voltage applied to said circuit means as the sensed pressure changes, thereby varying the duration of the period for which the switch means is closed in each operating cycle of the circuit means and therefore the fan motor speed as the sensed pressure changes.

Claim 16

In a refrigeration system, a condenser, means for circulating a refrigerant through said condenser, a fan for circulating air across said condenser to reduce the temperature of and thereby condense the refrigerant circulating therethrough, an electric motor for driving said fan, and control means including a pressure-responsive element capable of directly sensing the head pressure in said refrigeration system for varying the speed of said fan and the head pressure changes to prevent pressure from falling below a predetermined minimum during operation of said system, switch means connected between the fan motor and a source of operating voltage, whereby said motor is connected across said source of operating voltage and thereby energized when said switch means is closed, a source of control voltage, and cyclically operating circuit means connected between said source of control voltage and said switch means for opening and closing said switch means, said circuit means including means for varying the duration of the period for which said switch means is closed In each operating cycle of said circuit means as the control voltage applied to said circuit means is varied, said pressure-responsive element including a variable resistor connected between said control voltage source and said circuit means and means for varying the resistance of said resistor and therefore the control voltage applied to said circuit means as the sensed pressure changes, thereby varying the duration of the period for which the switch means is closed in each operating cycle of the circuit means and therefore the fan motor speed as the sensed pressure changes.