Thermostat controller

Abstract

A refrigeration system ( 10 ) has a compressor ( 12 ), condensor ( 13 ) and evaporator ( 14 ) connected in a refrigeration circuit. A controller ( 16 ) has probes ( 19, 20 ) for sensing the temperatures of the evaporator ( 14 ) and condensor ( 13 ) respectively. The controller controls the operation of the compressor, and hence the refrigeration circuit, so that the compressor does not start unless the evaporator temperature is above a preselected value (T start ), and stops the compressor if the evaporator temperature falls below T disable . An alarm ( 21 ) is activated if the condensor temperature rises above T alarm , and the controller ( 16 ) stops the compressor ( 12 ) if the condensor temperature rises above a higher temperature T shutdown .

1 . A refrigeration system having 
 a refrigeration mechanism for cooling an object, the refrigeration mechanism including a compressor, condensor and evaporator in a refrigeration circuit,    a thermostat means for regulating the operation of the refrigeration mechanism in response to the temperature of the object, and    wherein the refrigeration system further includes control means for controlling the refrigeration mechanism in response to the temperature of at least one component of the refrigeration mechanism, the control means overriding the normal operation of the thermostat means.    
     
     
         2 . A refrigeration system as claimed in    claim 1   , including a first sensor for sensing the temperature of the evaporator, the sensor being connected to the control means, 
 wherein the control means is responsive to the sensed temperature of the evaporator to control the operation of the refrigeration mechanism.    
     
     
         3 . A refrigeration system as claimed in    claim 2   , wherein the control means is responsive to the sensed evaporator temperature to stop operation of the refrigeration mechanism if the sensed evaporator temperature falls below a first predetermined temperature.  
     
     
         4 . A refrigeration system as claimed in    claim 3   , wherein the control means is responsive to the sensed evaporator temperature to prevent commencement of operation of the refrigeration mechanism if the sensed evaporator temperature is below a second predetermined temperature, the second predetermined temperature being higher than the first predetermined temperature.  
     
     
         5 . A refrigeration system as claimed in    claim 2   , including a second sensor for sensing the temperature of the condenser, the sensor being connected to the control means, 
 wherein the control means is responsive to the sensed temperature of the condenser to control the operation of the refrigeration mechanism.    
     
     
         6 . A refrigeration system as claimed in    claim 5   , further including an alarm, the alarm being activated by the control means if the sensed condensor temperature rises above a predetermined third temperature.  
     
     
         7 . A refrigeration system as claimed in    claim 6   , wherein the control means is responsive to the sensed condensor temperature to disable operation of the refrigeration mechanism if the sensed condensor temperature rises above a predetermined fourth temperature.  
     
     
         8 . A refrigeration system as claimed in    claim 1   , including a sensor for sensing the temperature of the condensor, the sensor being connected to the control means, 
 wherein the control means is responsive to the sensed temperature of the condenser to control the operation of the refrigeration mechanism.    
     
     
         9 . A refrigeration system as claimed in    claim 8   , further including an alarm, the alarm being activated by the control means if the sensed condensor temperature rises above a predetermined third temperature.  
     
     
         10 . A refrigeration system as claimed in    claim 9   , wherein the control means is responsive to the sensed condensor temperature to disable operation of the refrigeration mechanism if the sensed condenser temperature rises above a predetermined fourth temperature.  
     
     
         11 . A refrigeration system as claimed in    claim 1   , wherein the thermostat means and the control means are incorporated in an electronic control circuit.  
     
     
         12 . An electronic controller for a refrigeration system having a refrigeration mechanism for cooling an object, the refrigeration mechanism including a compressor, condenser and evaporator connected in a refrigeration circuit, the electronic controller including 
 a thermostat for regulating the operation of the refrigeration circuit in response to the temperature of the object,    at least one temperature sensor for sensing the temperature of at least one component of the refrigeration mechanism, and    an electronic control circuit responsive to the sensed temperature of the component(s) for controlling the operation of the refrigeration mechanism, the electronic control circuit overriding the operation of the thermostat.    
     
     
         13 . An electronic controller as claimed in    claim 12   , having a temperature sensor for sensing the temperature of the evaporator, the electronic control circuit being responsive to the evaporator temperature sensed by the sensor to disable operation of the refrigeration mechanism if the sensed evaporator temperature falls below a first predetermined value.  
     
     
         14 . An electronic controller as claimed in    claim 12   , having a temperature sensor for sensing the temperature of the condenser, the electronic control circuit being responsive to the condensor temperature sensed by the sensor to disable operation of the refrigeration mechanism if the sensed condensor temperature rises above a second predetermined value.  
     
     
         15 . An electronic controller as claimed in    claim 13   , having a second temperature sensor for sensing the temperature of the condenser, the electronic control circuit being responsive to the condensor temperature sensed by the second sensor to disable operation of the refrigeration mechanism if the sensed condenser temperature rises above a second predetermined value.  
     
     
         16 . A method of operating a refrigeration system having a refrigeration mechanism for cooling an object, the refrigeration mechanism including a compressor, condensor and evaporator connected in a refrigeration circuit, the method including the steps of using a thermostat to regulate the operation of the refrigeration mechanism in response to the temperature of the object, and overriding the normal operation of the thermostat and controlling the operation of the refrigeration mechanism in response to the sensed temperature of at least one component of the refrigeration mechanism.  
     
     
         17 . A method as claimed in    claim 16   , wherein the operation of the refrigeration mechanism is controlled in response to the sensed temperature of the evaporator, including the step of disabling operation of the refrigeration mechanism if the sensed evaporator temperature falls below a first predetermined value.  
     
     
         18 . A method as claimed in    claim 16   , wherein the operation of the refrigeration mechanism is controlled in response to the sensed temperature of the condenser, including the step of disabling operation of the refrigeration mechanism if the sensed condensor temperature rises above a second predetermined value.  
     
     
         19 . A method as claimed in    claim 17   , wherein the operation of the refrigeration mechanism is also controlled in response to the sensed temperature of the condensor, including the step of disabling operation of the refrigeration mechanism if the sensed condenser temperature rises above a second predetermined value.