Patent Application
20110091341
This application relates to properly positioning a scroll compressor crankcase and a non-orbiting scroll. Appropriate axial clearances are maintained to ensure efficient operation of the scroll compressor.
Scroll compressors have become widely utilized in refrigerant compression applications. In a typical scroll compressor, a first scroll member includes a base with a generally spiral wrap extending from the base. A second scroll member also has a base and a generally spiral wrap extending from its base. The two wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other, and as they orbit, the size of the compression chambers is decreased, compressing an entrapped refrigerant.
A separating force is created by the compressed refrigerant that tends to push the two scroll members away from each other. To entrap and define a compression chamber, the wrap of each scroll member must be in contact with the base of the other scroll member. The separating force tends to move the wraps out of engagement, and thus prevents compression. The orbiting scroll member rests on a crankcase within the scroll compressor. The crankcase holds the orbiting scroll member in position against the non-orbiting scroll member.
One challenge with scroll compressors is that the crankcase must maintain a critical axial clearance with the non-orbiting scroll member. In so doing, the crankcase and non-orbiting scroll member provide appropriate clearance for movement of the orbiting scroll member. To maintain the appropriate clearance, some crankcases include towers, which extend past the orbiting scroll member to contact the non-orbiting scroll member. These towers are often difficult to cast and machine. Further, providing packaging area for the towers constrains the size and design of other compressor components. It would be desirable to maintain appropriate clearance for the orbiting scroll member without using crankcase towers.
In a disclosed embodiment of this invention, a non-orbiting scroll member is secured to a compressor center shell and provides appropriate clearance for movement of an orbiting scroll member. A crankcase supports the orbiting scroll member, but the crankcase does not extend to contact the non-orbiting scroll member. Instead, the position of crankcase relative to the non orbiting scroll member is controlled using structural locators or spacers.
The present invention thus provides a method for maintaining adequate clearance for orbiting scroll member movement without relying on contact between the crankcase and the non-orbiting scroll member.
Features of this invention include controlling the installed position of the crankcase within a compressor center shell using a structural locator. Press tooling is typically used to install the crankcase within the compressor center shell. During assembly, the press tooling establishes the installed position of the crankcase based on the location of the structural locator. In one example, a step, a type of structural locator, on the press tooling contacts an edge of the compressor center shell to limit installation of the crankcase. As the non-orbiting scroll member attaches to the edge, appropriate clearances are maintained.
In another example, the compressor center shell includes a step for limiting installation of the crankcase. The position of the step within the compressor shell is based on the location of the edge of the compressor center shell. The step may be machined together with the edge of the compressor center shell. As the non-orbiting scroll member attaches to the edge, appropriate clearances are maintained.
Spacers may be used to position the crankcase relative to the non-orbiting scroll member. A spacer, such as a ring, positioned between the crankcase and the non-orbiting scroll member may force the crankcase into position as the non-orbiting scroll member is installed. Similarly, extensions on at least one of the crankcase, the orbiting scroll member or the non-orbiting scroll member may establish appropriate clearances. In such examples, frictional contact wears the extensions, and, after sufficient movement of the orbiting scroll member, appropriate clearance remains.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A scroll compressor 10 is illustrated in
A crankcase 42 supports the orbiting scroll member 22. A tower portion 46 of the crankcase 42 contacts the non-orbiting scroll member 26. In so doing, the tower portion 46 maintains adequate clearance between the crankcase 42 and the non-orbiting scroll member 26, which enables movement of the orbiting scroll member 22. The amount of clearance depends on the location of a tower face 50 contacting the non-orbiting scroll member 26 relative to the location of a crankcase face 54 supporting the orbiting scroll member 22. A back pressure chamber 56 biases the orbiting scroll member 22 toward the non-orbiting scroll member 26. A tap 51 taps compressed refrigerant into chamber 56.
The present invention does not rely on the tower portions 46 to maintain clearance for movement of the orbiting scroll member 22. Instead, as shown in
For example,
As is known, to assemble the crankcase 42 within the compressor center shell 58, press tooling 63 forces the crankcase 42 into the compressor center shell 58. In one example of the present invention, the press tooling 63 includes a structural locator 65 for contacting an edge portion 68 of the compressor center shell 58 to establish the appropriate installed position of the crankcase 42. Contact between the structural locator 65 and the edge portion 68 prevents the press tooling 63 from installing the crankcase 42 further into the compressor center shell 58. The structural locator 65 thereby physically prevents installation of the crankcase 42 further into the compressor center shell 58.
Once positioned within the compressor center shell 58, interference between the crankcase 42 and the compressor center shell 58 holds the crankcase 42 in position, and the press tooling 63 may be removed. Next, the non-orbiting scroll member 26 is secured in position using a compressor top shell 69 welded to the compressor center shell 58 (
The position of the step 62 is established based on a reference point 66, which is typically located near, or at, edge portion 68 of the compressor center shell 58. Tooling that forms the compressor center shell 58, and more specifically the edge portion 68 of the compressor center shell 58, also forms the step 62. Thus, a relationship between the step 62 and the reference point 66 is established when tooling the edge portion 68 of the compressor center shell 58. During assembly of the compressor 60, the non-orbiting scroll member 26 directly connects to the compressor center shell 58 at edge portion 68, which includes reference point 66. As a result, the step 62 position directly relates to position of the reference point 66 and the edge portion 68 thereby establishing an appropriate clearance between the two.
In another example, clearance C is establish using spacers 72 located on the orbiting scroll member 22, as shown in
Although in this example the spacers 72 are shown as a portion of the orbiting scroll member 22, other spacer locations are possible. For example, locating the spacers 72 on the crankcase 42 or the non-orbiting scroll member 26 may provide similar advantages.
In this example, the ring 76 is a thin ring having an axial thickness of less than 1.0 mm. Many ring 76 materials are possible, provided the material is capable of forcing the crankcase 42 into an installed position. For example, steel or plastic rings may be used.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art and having the benefit of this disclosure may recognize other modifications that would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope of coverage for this invention.
