Low charge protection vent

Abstract

A vent is included into a scroll compressor for protecting a refrigerant system in the event of loss of charge. The vent selectively taps an entrapped compression chamber to a housing chamber which surrounds the motor. In the event of a low charge, the gas in the compression chamber will be at a high temperature, and will heat the motor when the vent opens. The vented heated gas will then actuate a temperature protection device on the motor, causing the motor to stop rotation. In further embodiments, the compression chamber which supplies the tapped fluid is the discharge port.

1. A compressor comprising:
 a motor for driving a compressor element;  
 a protection device for said motor, said rotation device being actuated if  when  a predetermined temperature is exceeded at said motor;  
 a housing for enclosing said motor, said housing defining a housing chamber housing said motor;  
 a compression chamber for compressing a refrigerant, and said refrigerant passing through said housing chamber to said compression chamber, such that said refrigerant cools said motor; and  
 a vent for selectively communicating a fluid directly from an intermediate pressure portion of said compression chamber to said housing chamber, if  when conditions in a chamber intermediate a suction chamber and a discharge port occur because of a loss of charge in a system associated with said compressor, said vent allowing gas at an elevated temperature to move into said housing chamber and contact said motor, and actuate said protection device.  
 
     
     
       2. A compressor as recited in  claim 1 , wherein said compressor is a scroll compressor. 
     
     
       3. A compressor as recited in  claim 2 , wherein said vent is placed in a non-orbiting scroll of said scroll compressor. 
     
     
       4. As recited in  claim 1 , wherein said vent communicates with a discharge port. 
     
     
       5. A scroll compressor as recited in  claim 4 , wherein a valve is moveable dependent on the pressure difference between a suction tap and a tap to a compression chamber prior to discharge to selectively communicate said discharge pressure tap to said housing chamber. 
     
     
       6. A scroll compressor comprising:
 a housing defining a housing chamber;  
 an electric motor received in said housing chamber, said electric motor being provided with a protection device which is actuated when said motor reaches a predetermined temperature to stop rotation of said motor;  
 a supply of suction fluid communicating with said housing chamber such that said suction fluid cools said motor;  
 a first scroll member having a base and a generally spiral wrap extending from said base and a second scroll member having a base and a generally spiral wrap extending from said base, said wraps of said first and second scroll members interfitting to define compression chambers;  
 said motor driving said first scroll member to orbit relative to said second scroll member; and  
 a vent for selectively venting gas directly from an intermediate pressure portion of said compression chambers to said housing chamber, in the event that  when conditions in a chamber intermediate a suction chamber and a discharge port occur because of a loss of charge in a system associated with said compressor.  
 
     
     
       7. A scroll compressor as recited in  claim 6 , wherein said vent is mounted in said base of said second scroll member. 
     
     
       8. A scroll compressor as recited in  claim 7 , wherein a tap from said at least one compression chamber selectively passes to said housing chamber, said tap being selectively closed by a valve, said valve being held at a position allowing flow from said tap to said housing chamber, and said valve moving to a position blocking flow from said tap to said housing chamber if a pressure differential between the pressure in said compression chamber and said housing chamber exceeds a predetermined differential. 
     
     
       9. A scroll compressor as recited in  claim 8 , wherein a spring biases said valve toward a stop surface and to said position allowing flow from said tap to said housing chamber, and the pressure in said compression chamber selectively overcoming said spring force to move said valve to a position blocking flow from said tap to said housing chamber. 
     
     
       10. A scroll compressor as recited in  claim 8 , wherein a magnetic force holds said valve at a position allowing flow from said tap to said housing chamber, and the pressure in said compression chamber selectively overcoming said magnetic force and moving said valve to a position blocking flow from said tap to said housing chamber. 
     
     
       11. A scroll compressor as recited in  claim 8 , wherein a temperature sensitive element is associated with said valve, and holds said valve at a position blocking flow from said tap to said housing chamber until a predetermined temperature is exceeded at said element, said element being of a bi-metal composition which snaps to a second position once a predetermined temperature has been exceeded, said valve being capable of moving to said position allowing flow when said bi-metal element has moved to said second position. 
     
     
       12. A scroll compressor as recited in  claim 8 , wherein a temperature sensitive element is associated with said valve and holds said valve at a position blocking flow from said tap to said housing chamber until a predetermined temperature is exceeded at said element. 
     
     
       13. A scroll compressor as recited in  claim 8 , wherein said valve includes a spool valve and a closure valve, said pressure in said compression chamber communicating to a chamber acting on said closure valve and causing said closure valve to be biased toward said spool valve, an opposed side of said spool valve being communicated to said housing chamber pressure, and said closure valve being spring-biased to allow flow from said compression chamber to said opposed side of said spool valve, said compression chamber force biasing said closure valve to a first position blocking such flow unless the difference in pressure between said compression chamber and said housing chamber is less than a predetermined difference. 
     
     
       14. A scroll compressor as recited in  claim 13 , wherein said spool valve selectively closes a tap to discharge pressure when held in said first position, but allows flow from both said compression chamber and a discharge pressure tap when moved away from said first position. 
     
     
       15. A scroll compressor as recited in  claim 13 , wherein said spool valve selectively closes a tap to discharge pressure when held in said first position but allows flow from said discharge pressure tap when moved away from said first position. 
     
     
       16. A scroll compressor as recited in  claim 6 , wherein said compression chamber is a discharge port. 
     
     
       17. A scroll compressor as recited in  claim 16 , wherein a valve is moveable dependent on the pressure difference between a suction tap and a tap to a compression chamber prior to discharge to selectively communicate said discharge pressure tap to said housing chamber. 
     
     
       18. A scroll compressor comprising:
 a housing defining a housing chamber;  
 an electric motor received in said housing chamber, said electric motor being provided with a protection device which is actuated when said motor reaches a predetermined temperature to stop rotation of said motor;  
 a supply of suction fluid, said suction fluid communicating with said housing chamber such that said suction fluid cools said motor;  
 a first scroll member having a base and a generally spiral wrap extending from said base and a second scroll member having a base and a generally spiral wrap extending from said base, said wraps of said first and second scroll members interfitting to define compression chambers;  
 said motor driving said first scroll member to orbit relative to said second scroll member; and  
 a vent mounted in said base of said second scroll member, said vent including a valve biased towards a position selectively venting gas directly from an intermediate pressure portion of at least one of said compression chambers to said housing chamber, and said valve being moved to a position blocking venting of gas if  when conditions in a chamber intermediate a suction chamber and a discharge port corresponds to the compressor operating properly.  
 
     
     
       19. A scroll compressor comprising:
 a housing defining a housing chamber;  
 a first scroll member having a base and a generally spiral wrap extending from said base and a second scroll member having a base and a generally spiral wrap extending from said base, said wraps of said first and second scroll members interfitting to define compression chambers; and  
 a vent mounted in said base of said second scroll member, said vent including a valve biased towards a position selectively venting gas directly from an intermediate pressure portion of at least one of said compression chambers to said housing chamber, and said valve being moved to a position blocking venting of gas if  when conditions in a chamber intermediate a suction chamber and a discharge port corresponds to the compressor operating properly.  
 
     
     
       20. A scroll compressor as recited in  claim 19 , wherein said vented gas actuates a motor protection device of an electric motor which drives said first scroll member. 
     
     
       21. A scroll compressor as recited in  claim 19 , wherein said valve has a first face which is exposed to suction pressure and a second face exposed to a pressure within said at least one compression chamber, a bias member biasing said valve to a position allowing venting, and against a pressure from said at least one said compression chamber. 
     
     
       22. A compressor comprising:
   a motor driving compressor elements;        a protection device for said motor, said protection device being actuated when a predetermined temperature is exceeded at said motor;        a housing for enclosing said motor, said housing defining a housing chamber around said motor;        a compression chamber for compressing a refrigerant, and said refrigerant passing through said housing chamber to said compression chamber such that said refrigerant cools said motor; and        a vent for selectively communicating a discharge pressure refrigerant which has been compressed in said compression chamber to said housing chamber when conditions in an intermediate pressure chamber at a pressure intermediate a suction pressure and a discharge pressure occur because of a loss of charge in a system associated with said compressor, said vent allowing said discharge pressure refrigerant to move into said housing chamber and contact said motor, and actuate said protection device, and said vent including a valve which has one surface exposed to an intermediate pressure in said intermediate pressure chamber, and an opposed surface exposed to the suction pressure, with a spring biasing said valve in a direction against said intermediate pressure, said valve being biased by said spring towards a position which communicates said discharge pressure refrigerant to said housing chamber, with said intermediate pressure forcing said valve against a force from said spring to a position blocking flow of said discharge pressure refrigerant to said housing chamber.     
     
     
       23. A compressor as set forth in  claim 22 , wherein a tap to said discharge pressure refrigerant extends into a valve chamber from a position outward of an outer peripheral surface of said valve. 
     
     
       24. A compressor as set forth in  claim 23 , wherein said discharge pressure refrigerant does not bias said valve, with said valve being biased by said suction pressure, said intermediate pressure and said spring. 
     
     
       25. A compressor as set forth in  claim 22 , wherein said discharge pressure refrigerant is tapped from a discharge port on said compressor elements. 
     
     
       26. A compressor as set forth in  claim 22 , wherein said compressor elements include a scroll compressor. 
     
     
       27. A compressor comprising:
   a motor for driving a scroll compressor;        a protection device for said motor, said protection device being actuated when a predetermined temperature is exceeded at said motor;        a housing for enclosing said motor, said housing defining a housing chamber around said motor;        a compression chamber for compressing a refrigerant, and said refrigerant passing through said housing chamber to said compression chamber such that said refrigerant cools said motor; and        a vent for selectively communicating a discharge pressure refrigerant which has been compressed in said compression chamber to said housing chamber when conditions in an intermediate pressure chamber at a pressure intermediate a suction pressure and a discharge pressure occur because of a loss of charge in a system associated with said compressor, said vent allowing said discharge pressure refrigerant to move into said housing chamber and contact said motor, and actuate said protection device, and said vent including a valve which has one surface exposed to an intermediate pressure in said intermediate pressure chamber, and an opposed surface exposed to the suction pressure, with a spring biasing said valve in a direction against said intermediate pressure, said valve being biased by said spring towards a position which communicates said discharge pressure refrigerant to said housing chamber, with the pressure in said intermediate pressure chamber forcing said valve against a force from said spring to a position blocking flow of said discharge pressure refrigerant to said housing chamber, a tap to said discharge pressure refrigerant extending into a valve chamber for said valve from a position outward of an outer peripheral surface of said valve.     
     
     
       28. A compressor comprising:
   a motor for driving compressor elements;        a protection device for said motor, said protection device being actuated when a predetermined temperature is exceeded at said motor;        a housing for enclosing said motor, said housing defining a housing chamber around said motor;        a compression chamber for compressing a refrigerant, and said refrigerant passing through said housing chamber to said compression chamber such that said refrigerant cools said motor; and        a vent for selectively communicating a tapped refrigerant which has been compressed in said compression chamber to said housing chamber when conditions in an intermediate pressure chamber at a pressure intermediate a suction pressure and a discharge pressure occur because of a loss of charge in a system associated with said compressor, said vent allowing said tapped refrigerant to move into said housing chamber and contact said motor, and actuate said protection device, and said vent including a valve which has one surface exposed to an intermediate pressure in said intermediate pressure chamber, and an opposed surface exposed to the suction pressure, with a spring biasing said valve in a direction against said intermediate pressure, said valve being biased by said spring towards a position which communicates said tapped refrigerant to said housing chamber, with said intermediate pressure forcing said valve against a force from said spring to a position blocking flow of said tapped refrigerant to said housing chamber.     
     
     
       29. A compressor as set forth in  claim 28 , wherein said tapped refrigerant is at a discharge pressure. 
     
     
       30. A compressor as set forth in  claim 28 , wherein said compressor is a scroll compressor. 
     
     
       31. A compressor comprising:
   a motor for driving compressor elements;        a protection device for said motor, said protection device being actuated when a predetermined temperature is exceeded at said motor;        a housing for enclosing said motor, said housing defining a housing chamber around said motor;        a compression chamber for compressing a refrigerant, and said refrigerant passing through said housing chamber to said compression chamber such that said refrigerant cools said motor; and        a vent for selectively communicating a discharge pressure refrigerant which has been compressed in said compression chamber to said housing chamber when conditions in an intermediate pressure chamber at a pressure intermediate a suction pressure and a discharge pressure occur because of a loss of charge in a system associated with said compressor, said vent allowing said discharge pressure refrigerant at an elevated temperature to move into said housing chamber and contact said motor, and actuate said protection device, and said vent including a valve which has one surface exposed to an intermediate pressure in said intermediate pressure chamber, and an opposed surface exposed to the suction pressure, said discharge pressure refrigerant communicating through a chamber which contains said valve from a position radially outward of an outer peripheral surface of said valve, with said intermediate pressure forcing said valve to a position blocking flow of said discharge pressure refrigerant to said housing chamber.