System and method initiating defrost in response to speed or torque of evaporator motor

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for initiating a defrost cycle in response to a defrost enable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost initiating circuit generating the defrost enable signal when the speed/torque signal indicates a change in the motor speed/torque or a change in the motor torque whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure of the air flow;
• and
• wherein the energizing circuit includes a circuit controlling the speed/torque of the motor to maintain a motor speed for a period of time after the defrost cycle wherein the maintained motor speed corresponds to greater air flow than the air flow during the constant motor speed.

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for initiating a defrost cycle in response to a defrost enable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• a defrost initiating circuit generating the defrost enable signal when the speed/torque signal indicates a change in the motor speed/torque or a change in the motor torque whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure of the air flow;
• and
• a fast cool down circuit for operating the motor at an increased speed, torque or air flow rate for a period of time after a defrost cycle.

An apparatus for use with a refrigeration system including:

• a compartment to be refrigerated;
• a temperature sensor for sensing the temperature in the compartment;
• a compressor responsive to the temperature sensor for compressing a working fluid evaporated in an evaporator for cooling the compartment and condensed in a condenser remote from the compartment;
• and
• a defrosting circuit for defrosting the evaporator during a defrost cycle in response to a defrost enable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor to maintain a substantially constant air flow rate over the evaporator;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost initiating circuit responsive to the speed/torque signal and generating the defrost enable signal when the speed/torque signal indicates a change in the motor speed or a change in the motor torque whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure of the air flow.

A method of operating a refrigeration system including a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser, said method comprising the steps of:

• driving an air moving assembly with a motor to move air over the evaporator at a substantially constant air flow rate to cool a compartment;
• sensing a speed/torque of the motor;
• and
• initiating a defrost cycle in response to the sensed speed/torque of the motor when the motor speed changes or when the motor torque changes whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increase static pressure of the air flow.

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for initiating a defrost cycle;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit to maintain a substantially constant air flow rate over the evaporator;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• a defrost cycle sensing circuit responsive to the speed/torque signal and generating a defrost cycle signal provided to the control circuit when the speed/torque signal indicates a change in the motor speed or torque representing an defrost cycle;
• and
• wherein the control circuit deenergizes the motor for a first period of time in response to the defrost cycle signal whereby the motor does not rotate the air moving assembly during the defrost cycle.

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for initiating a defrost cycle in response to a defrost enable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost initiating circuit generating the defrost enable signal when the speed/torque signal indicates a change in the motor speed/torque or a change in the motor torque whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure of the air flow;
• and
• wherein the control circuit energizes the motor at a first speed or torque for a second period of time following the first period of time and wherein the control circuit energizes the motor at a second speed or torque different than the first speed or torque following the second period of time.

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for initiating a defrost cycle in response to a defrost enable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit to maintain a substantially constant air flow rate over the evaporator;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost initiating circuit responsive to the speed torque signal and generating the defrost enable signal when the speed/torque signal indicates that the air flow rate is less than a reference air flow rate whereby the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure of the air flow.

An apparatus for use with a refrigeration system including:

• a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser;
• and
• a control circuit for initiating operation of a refrigeration cycle and for defrosting the evaporator during a defrost cycle and for terminating the defrost cycle in response to a defrost disable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor in response to the control circuit;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost terminating circuit responsive to the speed/torque signal and generating the defrost disable signal when the speed/torque signal indicates a change during the defrost cycle in the motor speed/torque or a change during the defrost cycle in the motor torque whereby the defrost cycle is terminated in response to improvement of the refrigeration cycle as indicated by a reduction of frost or ice on the evaporator which increases air flow through the evaporator and decreases static pressure of the air flow.

An apparatus for use with a refrigeration system including:

• a compartment to be refrigerated;
• a temperature sensor for sensing the temperature in the compartment;
• a compressor responsive to the temperature sensor for compressing a working fluid evaporated in an evaporator for cooling the compartment and condensed in a condenser remote from the compartment;
• and
• a defrosting circuit for defrosting the evaporator during a defrost cycle and for terminating the defrost cycle in response to a defrost disable signal;
• the apparatus driving an air moving assembly moving air over the evaporator, said apparatus comprising:
• a motor including a rotatable assembly in driving relation to the air moving assembly;
• an energizing circuit selectively energizing the motor;
• a sensing circuit generating a speed/torque signal representative of a speed or a torque of the motor;
• and
• a defrost terminating circuit responsive to the speed/torque signal and generating the defrost disable signal when the speed/torque signal indicates a change during the defrost cycle in the motor speed or a change during the defrost cycle in the motor torque whereby the defrost cycle is terminated in response to improvement of the refrigeration cycle as indicated by a reduction of frost or ice on the evaporator which increases air flow through the evaporator and decreases static pressure of the air flow.

A method of operating a refrigeration system including a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser, said method comprising the steps of:

• driving an air moving assembly with a motor to move air over the evaporator to cool a compartment;
• sensing a speed/torque of the motor;
• and
• terminating a defrost cycle in response to the sensed speed/torque of the motor when the motor speed changes during the defrost cycle or when the motor torque changes during the defrost cycle whereby the defrost cycle is terminated in response to improvement of the refrigeration cycle as indicated by a reduction of frost or ice on the evaporator which increases air flow through the evaporator and decreases static pressure of the air flow.