Abstract:
A scroll compressor has lubricant flow which passes lubricant over a portion of a compressor pump set which will be at an elevated temperature under certain adverse conditions. If the adverse conditions are occurring, then this lubricant will reach an elevated temperature. This lubricant is returned over a motor protector such that it can cause the motor protector to trip and stop further operation of the scroll compressor. The flow of lubricant can be selective, and only occur when a predetermined temperature is reached by a sensing unit, or can be ongoing.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a system which optimizes the flow of a lubricant over portions of a scroll compressor which become hot during reverse rotation or loss of charge, and then passing the heated lubricant onto a motor protector. 
     Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor a first scroll member has a base and a generally spiral wrap extending from the base. The wrap of the first scroll member interfits with the wrap from a second scroll member. The second scroll member is caused to orbit relative to the first, and refrigerant is entrapped between the scroll wraps. As the second scroll member orbits the size of the compression chambers which entrap the refrigerant are reduced, and the refrigerant is compressed. 
     There are certain design challenges with a scroll compressor. As an example, while the scroll compressor efficiently compresses refrigerant when rotated in a proper forward direction, there are undesirable side effects if the scroll compressor is driven to rotate in a reverse direction. Moreover, if the level of refrigerant or charge level, being passed through the compressor is lower than expected, there may also be undesirable side effects. Among the many undesirable side effects is an increased heat level at the scroll compressor members. 
     One safety feature incorporated into most sealed compressors is the use of a motor protector associated with the electric motor for driving the compressor. The same is true in a scroll compressor, wherein a motor protector is typically associated with the stator for the electric motor. The motor protector operates to stop rotation of the motor in the event there is an electrical anomaly, or if the motor protector senses an unusually high temperature. However, the problems mentioned above with regard to reverse rotation and loss of charge typically cause heat to increase at the compressor pump set, or the scrolls, which is relatively far from the motor. Thus, it may take an undue length of time for the additional heat being generated in the compressor pump set to pass to the motor protector. 
     SUMMARY OF THE INVENTION 
     In the disclosed embodiment of this invention, lubricant is caused to flow over a portion of the compressor pump set and be heated, at least when there are adverse conditions in the compressor pump set. This heated lubricant is then passed to a motor protector. This will cause the motor protector to trip the motor and stop further rotation. 
     In preferred embodiments, the heated portion of the compressor over which the lubricant is passed is the non-orbiting scroll. Alternatively, in some embodiments the heated lubricant can pass over the orbiting scroll. 
     In one general type of disclosed embodiment, the flow of lubricant back to the motor protector is selective, and will only occur if a particularly high temperature is reached. At other times, the lubricant is directed to a normal return path. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following which is a brief description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view through a first embodiment compressor. 
     FIG. 2 is a cross-sectional view through a second embodiment scroll compressor. 
     FIG. 3 shows a modification to the FIG. 2 embodiment. 
     FIG. 4 is an enlarged view of a portion of the FIG. 3 embodiment. 
     FIG. 5 shows yet another embodiment. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a scroll compressor  20  having a compressor pump set  22  which incorporates an orbiting scroll and a non-orbiting scroll  25 , as known. A compressor rotor  26  drives a shaft  27  to drive the orbiting scroll, as known. A motor protector  28  is associated with the motor stator  29 . A lubricant level  30  is positioned beneath the motor. An oil feed tube  32  extends upwardly from the lubricant sump  30  and a lubricant is driven through a pump  34  on the feed tube  32 . The pump  34  may be driven by any known means. As an example, a separate motor may be provided, or the motor could be driven by a power takeoff from the shaft  27 . This figure shows the pump  34  schematically, and a worker in this art would recognize how to drive the motor  34 . The tube  32  has downstream portions  36  and  38  downstream from the pump  34 . These portions pass over the non-orbiting scroll  25 . An outlet  40  is positioned above the motor protector  28 , such that heated lubricant  42  is returned onto the motor protector  28 . 
     In operation, should conditions within the compressor pump set  22  be as expected, the lubricant  42  will not be at a predetermined high temperature. That is, while the lubricant  42  may be heated, it will not be heated to a sufficient amount that it will trip the motor protector  28 . However, should there be an adverse condition in the compressor pump unit  22 , such as reverse rotation or a loss of charge situation, then the temperature of the lubricant  42  will be elevated. Once the temperature reaches a predetermined amount it will trip the motor protector  28  and cause the motor protector  28  to stop further rotation of the motor. 
     FIG. 2 shows another embodiment  50 . In embodiment  50 , the orbiting scroll  52  is associated with the non-orbiting scroll  54 . A crankcase  56  supports the orbiting scroll  52  and has a lubricant passage  58  communicating with a shaft  27 . The shaft  27 , shown schematically here, is configured to have a lubricant feed tube  59  supplying lubricant to the chamber  61 . This portion of the invention is as known in the scroll compressor art. The passage  58  communicates with a tube  60  having a tube end  62  received in an opening  64  which communicates with the passage  58 . The tube  60  further has a second end  66  inserted into a bore  68  in the non-orbiting scroll  54 . This passage  68  communicates with a further passage  70  which wraps around the body of the non-orbiting scroll  54 , and then communicates with an outlet  40  much like the outlet shown in FIG.  1 . This embodiment differs from the FIG. 1 embodiment largely in the fact the oil feed is obtained from the passage  58 , rather than directly from the sump. The pumping action of the passage  59  will drive the lubricant through its path in this embodiment. 
     FIGS. 3 and 4 shows a further embodiment  80  which is slightly modified from the FIG. 2 embodiment. In this embodiment the oil tube  82  includes a downwardly extending return opening  84  selectively closed by a plug  86 . The plug  86  is connected to a cord  88  which extends through a small passage  89  to an actuator mechanism  90 . 
     As shown in FIG. 4, the mechanism  90  incorporates a clip spring  92  having a clip end  94  positioned outwardly of a housing  104 . This holds a spring member  96  at a predetermined position. The member  92  is formed of a shape memory alloy tension spring. As this member increases in temperature, it will contract in length or size. A second spring  98  is applying a bias force through a spring end  102  sitting against a flange  100  which is part of the spring  92 . 
     During normal operation, the spring  98  holds the spring  92  and cord  88  in the position illustrated in FIGS. 3 and 4. The plug  86  is allowed to move downwardly to the position such as shown in FIG.  3 . However, should the temperature on the spring  92  increase beyond a predetermine level, it will begin to contract in size. As it contracts in size it overcomes the force from spring  98  and the cord  88  is pulled to the right in FIG.  4 . This pulls the plug  86  upwardly such that it will close the opening  84 . At that time, lubricant will flow upwardly and into the passage  68 - 70 , such as explained with reference to FIG.  2 . From the passage  70  the lubricant is returned such as through an outlet  40  directed above a motor protector  28 . This embodiment provides a system wherein the lubricant is only passed over the non-orbiting scroll in the event that a predetermined condition is likely to exist. The lubricant will thus be heated such that it will trigger the motor protector, and stop operation under adverse conditions. 
     FIG. 5 shows another embodiment  106 , wherein a passage  108  communicates with a normal oil return path tube  110 . Oil will return from passage  108  back downwardly through the tube  110 . A valve  112  selectively closes this path when a spring  114  force is overcome by a spring  116 . The spring  114  pulls the valve  112  upwardly. The spring  116  is a temperature sensitive spring and will increase in the length as its temperature increases. As the temperature surrounding the valve  112  increases, the spring  116  will force the valve  112  downwardly to close communication between passages  108  and  110 . At that time, lubricant within a chamber  118  will no longer move into the passage  108 . Instead, the lubricant will be forced upwardly into a passage  120 , and from passage  120  it will communicate with an alternative oil path  124  which is positioned above the motor protector  28 . The positioning of the passage  120  closer to the orbiting scroll  125  ensures that better heat transfer is achieved. That is, the passage  120  is closer to the orbiting scroll  125  than is passage  108 . 
     While the invention has been disclosed for reacting to a predetermined high temperature, it should be understood that other conditions could cause the actuation. As an example, high pressure ratios or low suction pressure. 
     Although preferred embodiments of this invention have been disclosed, a worker in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.