Oil return for reduced height scroll compressor

This application relates to a unique method and apparatus for returning the oil to a sump in a sealed compressor.

Sealed compressors are utilized in many refrigerant compression applications. In a typical sealed compressor, a pump unit is incorporated within a hermetically sealed housing. A refrigerant is introduced into the housing in a suction chamber through a suction tube. Typically, an electric motor drives a shaft which powers the pump unit. This refrigerant passes over the electric motor, cooling the motor. The refrigerant then passes into the pump unit, is compressed, and is passed to a discharge chamber. The suction and discharge chamber are separated by appropriate structure.

In one popular type of compressor pump unit, the compressor pump unit comprises a pair of scroll members. A scroll compressor includes two opposed scroll members each having a base and a generally spiral wrap extending from the base. One of the two scroll members is caused to be driven to orbit relative to the other. The wraps interfit, and as the wraps orbit, compression chambers defined between the wraps are reduced in volume.

Typically, sealed compressor housings have been a relatively long length. The suction tube has generally entered the chamber at a location aligned with the pump unit, or at least between the pump unit and the top end of the motor stator windings.

More recently, it has become desirable to reduce the height of sealed compressors, and in particular scroll compressors. However, certain problems become introduced with the reduced height sealed compressor. In one example, oil must be returned from the pump unit to a sump in the compressor. The oil will typically fall from the pump unit downwardly to the sump. However, it is also desirable to ensure that the oil is isolated from suction gas turbulence, as this could cause undesirable entrainment of the oil into the refrigerant entering the chamber.

This problem becomes particularly acute when the height is reduced, as it becomes more difficult to ensure that the returned oil does not pass in front of the suction tube.

In a disclosed embodiment of this invention, a sealed compressor incorporates a suction tube which is at least partially aligned with the windings on the motor stator for driving a compressor pump unit. An oil return tube returns oil from the compressor pump unit through a tube, and confines the oil return to a circumferential extent which does not include the suction tube. That is, the oil return tube ensures that the oil does not pass in front of the suction gas entering the compression chamber. Stated another way, the oil return structure prevents the returned oil from mixing with the suction gas.

In a preferred embodiment, the oil return tube is at a location generally opposed by 155° from the suction tube.

These and other features of the present invention can be best understood from the following specifications and drawings, the following of which is a brief description.

FIG. 1A is a cross-sectional view of a scroll compressor incorporating the present invention.

FIG. 1B is an enlarged view of one portion of FIG. 1 A.

FIG. 2 is a cross-sectional view of the small portion of the motor of the present invention.

FIG. 3 shows oil supply structure.

FIG. 4 shows another embodiment.

FIG. 5 shows an end view of the FIG. 4 embodiment.

FIG. 6 shows an alternative embodiment.

FIG. 7 shows yet another alternative.

A scroll compressor 20 is illustrated in FIGS. 1A and 1B incorporating a orbiting scroll 22 , and a non-orbiting or fixed scroll 24 . A motor 26 has stator windings 27 driving a shaft 28 through a motor rotor 30 . Shaft 28 and motor stator 26 are positioned above an oil sump 29 . A suction tube 31 enters a compressor housing 32 within the axial extent of the windings 27 . Tube 31 supplies refrigerant into a space 38 which communicates with the scroll compressor chambers. In the prior art, the suction tube typically was above the stator windings 27 , and perhaps aligned with the pump unit components 22 and 24 . As shown, a crankcase 33 supports the orbiting scroll 22 .

An oil return chamber 34 is defined between the crankcase 33 and the orbiting scroll 22 . An oil return passage 36 extends radially outwardly from the changer 34 . A tube 40 is pressed into the passage 36 , and has radially outer burrs 42 for being sealed within the passage 36 . The tube 40 also has a downwardly extending portion 44 extending to a radially outwardly extending spout 46 which throws the oil outwardly against an inner wall 49 of the housing 32 . The oil may then pass downwardly through a clearance 50 between the stator 26 and the inner wall 49 of the housing 32 .

The present invention provides the benefit of returning oil from the chamber 34 downwardly to the sump 29 while isolated from suction gas turbulence. Stated another way, the present invention is directed to preventing return oil from being entrained in the refrigerant entering through the suction tube 31 . The entrainment of oil into the suction tube introduced refrigerant becomes a particularly acute problem when the height of the compressor is reduced to move the suction tube to be aligned with the motor winding.

As can be appreciated from FIG. 2 and FIG. 1A, a recess 47 is formed in the outer periphery of the windings 27 to receive the tube 44 . Recess 47 can be formed by blanking the windings, as known. This allows the tube to still be closely adjacent to an inner surface 49 of the housing 32 without requiring the motor windings to be spaced from the surface 49 by an undue amount. Further, this also provides better protection separating the returned oil from the refrigerant entering space 38 .

As can be seen in FIG. 3 and FIG. 1A, an oil supply hole 60 extends through the shaft 28 , and supplies lubricant to the location of the orbiting scroll 22 . A bearing 62 supports an upper end shaft 28 within the orbiting scroll 22 .

As can be best appreciated from FIG. 3, a passage 64 communicates radially outwardly through the shaft 28 at the location of the bearing 62 . Passage 64 communicates with a passage 66 extending upwardly and having a blind end 68 . The passage 66 does not extend to the bottom end of the bearing 62 . Thus, the oil supply to the bearing will tend to flow upwardly, and then will fall into the chamber 34 . Thus, a good deal of the oil supply to the bearing 62 will be returned to the chamber 34 .

In this way, the inventive oil return structure will be likely to segregate a very large majority of the oil supplied to the compressor pump unit from the suction tube 31 .

FIG. 4 shows another embodiment 79 wherein the passage 80 in the crankcase 33 extends outwardly toward the center shell 82 . A partial tube 84 is again received in the passage 80 , in a manner similar to the earlier embodiment. The tube 84 has a lower end 86 opening into a chamber 89 . A shield 88 defines the chamber 89 . It should be understood that the shield 88 need not provide a gas-tight seal on tube 84 , as the purpose of the shield 88 is merely to prevent mixing between the returned oil and the suction gas.

In this embodiment, the winding 27 is not necessarily deformed, and the chamber 89 communicates with a clearance 90 between the stator and the shell housing 82 .

As shown in FIG. 5, the shield is planar 88 extends between two ends 92 which contact the center shell 82 . In this way, the chamber 89 is defined. That is, the shield generally extends along a line between the two ends 92 and contacts the cylindrical shell 82 at the two ends 92 .

FIG. 6 shows an alternative embodiment shield 96 , wherein ends 98 extend from a central portion toward the shell 82 . Here the chamber 100 is defined between the ends 98 and the shield 96 . The shields 88 and 96 could be formed of sheet metal, plastic, or any suitable material.

FIG. 7 shows yet another embodiment 101 , wherein the shield 102 extends from the crankcase 33 downwardly to move beyond the motor windings 27 . Essentially, this embodiment eliminates the tube 84 from the FIG. 4 embodiment. This embodiment communicates the chamber 104 at the end of the passage 80 directly into a chamber 103 defined by the shield 102 . The shield could have the configuration shown in FIG. 5 or FIG. 6 .

It should be understood that while the majority of oil being returned to the sump should pass through the oil shields, etc. of this invention, some oil may still pass through other structures back downwardly to the sump. The main purpose of this invention is to isolate a substantial quantity of the oil.

Although the invention has been disclosed with reference to a scroll compressor, it should be understood that other sealed compressors would benefit from this invention.

Although a preferred embodiment has been disclosed, a worker of ordinary skill in this art would recognize that 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.