Abstract:
A check valve retainer for a scroll compressor includes a retaining lip that fits into a recess formed in a scroll. The retaining lip may be manufactured as an integral part of the check valve retainer for press fitting or may be formed by an expansion fit locking member having a protrusion that forces a portion of check valve retainer wall into the recess. The retaining lip ensures that the check valve retainer stays attached to the scroll without risking scroll deformation.

Description:
TECHNICAL FIELD 
     The invention relates to scroll compressors, and more particularly to a retainer structure for a compressor check valve. 
     BACKGROUND OF THE INVENTION 
     Scroll compressors are widely used in refrigerant compression applications. A scroll compressor typically includes two interfitting scroll members. Each scroll member has a base with a generally spiraling scroll wrap extending from the base. The wraps interfit to define a plurality of compression chambers. One scroll member acts as a non-orbiting scroll member and maintains a fixed position while the other scroll member acts as an orbiting scroll member and rotates relative to the non-orbiting scroll member. The relative rotation causes the wrap in the orbiting scroll member to orbit relative to the wrap in the non-orbiting scroll member, changing the volume of the compression chambers. This changing volume compresses refrigerant trapped in the compression chambers. 
     When the compressor is shut down residual pressure caused by compressed gas trapped between the wraps and contained within other compressor components, such as in a discharge plenum, discharge lines and/or a condenser, may drive the orbiting scroll in a reverse direction. This reverse rotation may continue until pressures on the high pressure side of the system equalize with pressures on the low pressure side of the system. This prolonged reverse rotation is undesirable. 
     To minimize or prevent reverse rotation from occurring, scroll compressors often have a check valve that moves between an open position and a closed position. The check valve opens when the compressor is compressing refrigerant, but quickly closes when the compressor shuts down. The check valve therefore prevents the flow of compressed refrigerant back into the compressor chambers upon shutdown, limiting the amount of trapped gas communicating with the compression chambers and reducing the occurrence of reverse rotation. 
     If the check valve is a disc-type check valve, a check valve retainer keeps in the check valve within a discharge cavity. The check valve retainer may be held in the non-orbiting scroll member via an interference fit, but interference fits often require precise tolerances to ensure proper seating of the check valve. If there is too little interference between the check valve and the bore, the check valve retainer tends to unseat itself, but too much interference may cause distortion of the non-orbiting scroll. 
     There is a desire for a check valve retainer structure that reliably fits into the non-orbiting scroll. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a scroll compressor having a check valve retainer with a retaining lip that keeps the check valve retainer in a scroll. The retaining lip fits into a recess formed on an inner wall of a discharge cavity in the scroll. To attach the check valve retainer to the scroll, an expansion fit locking member having a protrusion forces a portion of check valve retainer wall into the recess. The retaining lip ensures that the check valve retainer stays attached to the scroll without risking scroll deformation. 
     In an alternative embodiment, the retaining lip is manufactured as an integral part of the check valve retainer. The check valve retainer is then press fit into the scroll, allowing the retaining lip to flow into the recess. Other possible embodiments include separate locking devices that wedge the retainer into the scroll. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a portion of a scroll compressor incorporating one embodiment of the check valve retainer before full assembly; 
     FIG. 2 illustrates the check valve retainer in FIG. 1 after full assembly; 
     FIG. 3 illustrates another embodiment of the inventive check valve retainer; 
     FIG. 4 illustrates a further embodiment of the inventive check valve retainer; 
     FIG. 5 illustrates yet another embodiment of the inventive check valve retainer; 
     FIGS. 6 and 7 illustrate a further embodiment of the inventive check valve retainer; and 
     FIG. 8 illustrates a scroll in which the check valve retainer may be incorporated. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIGS. 1 and 2 illustrate a scroll  100   a  incorporating a check valve retaining structure  101  according to one embodiment of the invention. FIG. 8 illustrates an operating environment of the check valve retaining structure; as shown in FIG. 8, the check valve retaining structure is disposed in the fixed scroll  100   a  while an orbiting scroll  100   b  orbits within the fixed scroll  100   a . As shown, the non-orbiting scroll  100  has a discharge cavity  104 . A check valve assembly includes a valve member, such as a check valve disc  106 , which is disposed in the cavity  104  and seated on a valve seat  107 , and a check valve retainer  108  having an outlet port  109  and side walls  110 . During compressor operation, the check valve disc  106  prevents return flow of compressed gas within the compressor and therefore limits reverse orbital movement of the orbiting scroll member. 
     More particularly, the check valve disc  106  moves up and down within the discharge cavity  104 , thereby opening and closing a discharge port  111 , due to gas pressure differences between the discharge port  111  and the discharge cavity  104 . As gas pushes the check valve disc  106  upward in the discharge cavity  104 , the disc  106  stops against retainer  108  and gas escapes through the discharge port  111  around the edges of the check valve disc  106  and openings  107  around the edge of the retainer  108 . When the compressor shuts down, gas rushes through the outlet port  109  and forces the check valve disc  106  back down to the valve seat  107 . 
     In the embodiment shown in FIGS. 1 and 2, a recess  112  is formed into an inner wall of the discharge cavity  104  and the check valve retainer  108  is slip-fitted into the cavity  104 . The recess  112  may be formed via any manufacturing process, such as cutting or coining. Further, although the Figures illustrate a recess  112  having a rectangular cross-section, the recess  112  may have any desired cross section, such as triangular, curved, etc. 
     A locking member  116  having a protrusion  118  formed around its outer surface is placed inside the check valve retainer  108  so that the side walls  110  of the check valve retainer  108  are sandwiched between the inner wall of the discharge cavity  104  and the locking member  116 . As shown in FIG. 1, the recess  112  and protrusion  118  align with each other, trapping a portion of the check valve retainer side wall  110  therebetween. The locking member  116  preferably is an expansion fit component designed to expand when a mandrel, power screw, hydraulic tool, or other similar tool (not shown) is pushed into the component. 
     As shown in FIG. 2, forcing a mandrel into the locking member  116  expands the locking structure  116  outward as shown by arrows A, pushing the protrusion  118  outward toward the recess  112 . During expansion, the protrusion  118  pushes against and deforms the check valve retainer side wall  110 , forcing a portion of the side wall  110  into the recess  112  to form a retaining lip  120  that holds the check valve retainer  108  within the discharge cavity  104 . For this embodiment, the check valve retainer  108  preferably is made of a deformable material that can flow into the recess  112  while maintaining sufficient strength to hold the retainer  108  in the cavity  104 . 
     Although FIGS. 1 and 2 illustrate forming the retaining lip  120  in the check valve retainer using an expansion fit locking member  116 , any other structures (e.g., clips, expanding coils, etc.) may act as the locking member  116  without departing from the scope of the invention. 
     FIG. 3 illustrates a non-orbiting scroll incorporating a check valve retaining structure according to another embodiment of the invention. In this embodiment, the check valve retainer  300  has a retaining lip  120  integrally formed around at least a portion of its circumference. Because the retaining lip  120  is already manufactured into the check valve retainer  300 , this embodiment does not require a separate locking member to form the lip  112  and lock the check valve retainer  300  in place. Instead, the check valve retainer  300  in this embodiment is simply press-fitted into the discharge cavity  104  so that the retaining lip  120  snaps into the recess  112  automatically. One or more splits  302  cut into the check valve retainer  300  allows the retainer  300  to deform slightly as it is pressed into the discharge cavity and spring back into its proper shape when the retainer  300  reaches the correct depth to allow the lip  120  to engage with the recess  112 . The check valve retainer  300  material preferably has some resilience so that the check valve retainer  300  can slip into the cavity  104  while still providing enough outward force to keep the retaining lip  120  securely in the recess  112 . 
     Note that other possible engagement structures may be incorporated into the check valve retainer and the recess without departing from the scope of the invention. For example, the retaining lip  120  and the recess  112  may be threaded to stop the retainer when it is at a desired orientation within the cavity  104 . Further, the recess  112  does not need to be one continuous recess  112 , but may instead be a series of short grooves or dimples encircling the inner wall of the cavity  104 . 
     FIGS. 4 through 6 illustrate alternative embodiments that incorporate retention interfaces other than a retaining lip and recess structure inside the cavity. FIG. 4 illustrates a check valve retainer  400  that is placed inside the discharge cavity  104  and held in place by a retaining pin  402  inserted through holes  404  in the scroll  100 . In one embodiment, the retaining pin  402  wedges itself against the check valve retainer  400  to create an interference fit. As a result, the retainer  400  itself does not need to be machined to form an interference fit itself inside the cavity  104 . 
     FIG. 5 illustrates another embodiment of the invention. In this embodiment, an interference fit between the retainer  500  and the inside of the discharge cavity may also be formed by placing a staking pin  502  on the scroll  100  after a retainer  500  has been inserted into the cavity  104  and imparting a blow to the staking pin  502  to deform the scroll  100  slightly to hold the retainer  500  in place through an interference fit. More particularly, the staking pin  502  forms one or more staked points  504  when struck, pushing the scroll  100  material downward and inward against the retainer  500 . Like the embodiment in FIG. 4, this embodiment creates an interference fit for the retainer  500  after the retainer  500  has been inserted into the cavity  104 . 
     FIGS. 6 and 7 illustrate yet another possible embodiment of the invention. In this embodiment, the scroll  100  has a groove  600  formed on an outer wall of the discharge cavity  104  and the check valve retainer  602  is formed with a flange  604 . During assembly, the check valve retainer  602  is inserted into the cavity  104  with the flange  604  disposed outside of the cavity  104 . The flange  604  is then crimped or rolled into the groove  600  to form a lip  606  that engages with the groove  600 , holding the retainer  602  in place. This embodiment makes it easy to deform the retainer  602  without requiring any modification of the inside of the cavity  104 . 
     As a result, one embodiment of the inventive structure incorporates a recess in an inner wall of the discharge cavity and a complementary retaining lip in the check valve retainer to hold the check valve retainer in place. The retaining lip can either be formed as a integral part of the check valve retainer during manufacturing (allowing the retainer to be press fit into the cavity) or by forcing an expansion fit member having a protrusion into the check valve retainer, deforming a portion of the check valve retainer to form the retaining lip. The retaining lip keeps the check valve retainer in place without relying upon an interference fit that may distort the non-orbiting scroll or not provide enough retention force. Other embodiments of the invention include deforming the scroll and/or the check valve retainer after they are coupled together to form an interference fit or other gripped fit between the two components. 
     Although preferred embodiments of this invention have been disclosed, a worker of ordinary skill in the 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.