Optical frost detector with gas blow off

Abstract

A frost detector, system, and method for controlling frost formation on the evaporator of a device operating in a refrigeration cycle by initiating defrost cycles when frost is optically detected. The system includes apparatus for delivering gas at a volume and velocity sufficient to remove residual water and debris from the frost detector of the system that might degrade performance if not removed. When frost is detected, a signal is sent to a controller which activates a defrost cycle.

1 . A frost detector comprising:
 a body including a target and an optical sensor assembly comprising apparatus for emitting electromagnetic radiation at a selected wavelength at said target and apparatus for receiving electromagnetic radiation reflected from said target, and circuits capable of detecting changes between said emitted electromagnetic radiation and said received electromagnetic radiation caused by the presence of frost on said target,   at least one gas flow conduit configured to allow gas to be blown onto said target to remove material collected on said target.   
     
     
         2 . The frost detector of  claim 1  further comprising a controller for controlling a flow of gas through said at least one gas flow conduit. 
     
     
         3 . The frost detector of  claim 1  further comprising a source of pressurized gas in gas communication with said gas flow conduit. 
     
     
         4 . The frost detector of  claim 3  further comprising a valve for controlling a flow of said gas from said source of pressurized gas. 
     
     
         5 . The frost detector of  claim 3  wherein said source of pressurized gas is selected from the group consisting of a pressure container and a pump. 
     
     
         6 . The frost detector of  claim 4  wherein said source of pressurized gas comprises a pressure container and a pump for providing gas under pressure to said pressure container. 
     
     
         7 . The frost detector of  claim 6  further comprising a controller for controlling at least one of said pump and said valve. 
     
     
         8 . The frost detector of  claim 2  wherein said controller initiates a defrost cycle upon detection of a predetermined level of frost formation on said target. 
     
     
         9 . The frost detector of  claim 2  wherein said controller halts said deicing cycle based on input received from at least one device selected from the group consisting of said optical sensor assembly, a temperature sensor, a refrigeration gas pressure sensor, and a timer. 
     
     
         10 . The frost detector of  claim 1  further comprising at least one air flow conduit configured to allow air to be blown onto said body to remove material from said body. 
     
     
         11 . The frost detector of  claim 1  wherein said body comprises a material selected to enhance thermal conduction. 
     
     
         12 . The frost detector of  claim 1  wherein said target comprises a shape selected to enhance the shedding of condensed water droplets. 
     
     
         13 . The frost detector of  claim 1  wherein said body includes a coating material selected to enhance the shedding of condensed water droplets. 
     
     
         14 . The frost detector of  claim 1  configured to be affixed to an evaporator coil of a refrigeration assembly. 
     
     
         15 . The frost detector of  claim 1  configured to be detachably coupled to an evaporator coil of a refrigeration assembly. 
     
     
         16 . The frost detector of  claim 1 , configured, and positioned on an evaporator coil, to approximate at said target the frost forming and defrosting conditions experienced by said evaporator coil. 
     
     
         17 . The frost detector of  claim 1  further comprising a temperature sensor mounted with said body. 
     
     
         18 . The frost detector of  claim 1  further comprising at least one temperature sensor positioned on an evaporator. 
     
     
         19 . The frost detector of  claim 1  installed in a refrigeration system. 
     
     
         20 . The frost detector of  claim 1  further comprising a window covering said apparatus for emitting electromagnetic radiation at a selected wavelength at said target and said apparatus for receiving electromagnetic radiation reflected from said target. 
     
     
         21 . The frost detector of  claim 20  wherein said gas flow conduit is further configured to allow gas to be blown onto said window to remove material collected on said window. 
     
     
         22 . The frost detector of  claim 1  wherein said body further comprises a heating element.