Electrochemical machining of scroll wraps

• US 5,320,505 A
• Filed: 03/04/1993
• Issued: 06/14/1994
• Est. Priority Date: 03/04/1993
• Status: Expired due to Fees

• Current Assignee: Tecumseh Products Company
• Original Assignee: Tecumseh Products Company
• Inventors: Bourg, John M., Misiak, Michael W.
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US08/026,522
• Time in Patent Office: 467 Days
• Field of Search: 418/55.2, 418/55.1, 29/825, 204/224 M, 204/212, 204/129.5, 204/129.7
• US Class Current: 418/55.1
• CPC Class Codes: B23H 3/00 Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
• CPC Class Codes: B23H 9/10 Working turbine blades or nozzles
• CPC Class Codes: F04C 18/0215 where only one member is moving
• CPC Class Codes: F04C 18/0246 Details concerning the involute wraps or their base, e.g. geometry
• CPC Class Codes: F04C 2230/101 by electrochemical methods
• CPC Class Codes: F04C 2270/17 Tolerance; Play; Gap
• CPC Class Codes: F05B 2230/101 by electrochemical methods
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A method and apparatus for electrochemically machine lapping a matched set of fixed and orbiting scroll members for use in a scroll compressor. The orbiting scroll member is orbited in a short stroke relative to the fixed scroll member while an electrolyte is pumped between the scroll wraps. An electric current is passed through the fixed and orbiting scroll wraps to thereby electrochemically machine away high profile areas on corresponding metal wear surfaces. During the machining process, the clearance spacing between the scrolls is tightly controlled to prevent contact between the scrolls.

Claims

1. A method for electrochemical machine lapping a set of two scroll members, said method comprising:

intermeshing said scroll members so that a clearance space exists between said scroll members;

pumping an electrolyte into said clearance space; and

applying an electric current between said scroll members and through said electrolyte, whereby electrochemical removal of metal from said scroll set takes place.

2. The method of claim 1 in which said intermeshed scroll members are orbited relative to each other, thereby causing removal of metal adjacent all wear surfaces.

3. The method of claim 1 further comprising the step of orbiting said intermeshed scroll members relative to each other in a short stroke.

4. The method of claim 3 in which said intermeshed scroll set includes a suction opening and a discharge opening, both communicating with said clearance space, said orbiting motion of said intermeshed scroll members creating suction at said suction opening.

5. The method of claim 1 in which each said intermeshed scroll member includes a wrap attached to a base plate, said intermeshed members spaced apart so that the minimum clearance space between said scroll wraps is substantially equal to the clearance space between each said wrap and an opposing scroll base plate.

6. A method of treating the surface areas of interfitting scroll members to reduce leak paths between said members, said method comprising:

orbiting said interfitting scroll members relative to one another;

exposing the surface areas between said scroll members to an electrolyte solution; and

applying a voltage across said scroll members to electrochemically remove portions of said scroll member surface areas thereby reducing leak paths therebetween.

7. The method of claim 6 further comprising preventing contact between said scroll members.

8. The method of claim 6 further comprising pumping the electrolyte between said scroll members.

9. A compressor comprising:

a housing;

a scroll set disposed within said housing, said scroll set including a fixed scroll member and an orbiting scroll member both having electrochemically machined surfaces prepared by orbiting said scroll members together, exposing areas between said scroll set to an electrolyte solution, and applying an electric charge to one of the scroll members to electrochemically remove portions of said scroll set; and

drive means to orbit said orbiting scroll relative said fixed scroll.

10. The compressor of claim 9 in which said scroll members have electrochemically machined surfaces having a finish of 70 Ra or less.

11. An apparatus for electrochemically machining the respective surfaces of a complementary pair of fixed and orbiting scroll members for use in a scroll compressor, comprising:

a mechanism for holding the fixed and orbiting scroll members in aligned positions such that the involute wrap faces of the fixed and orbiting scroll members interfit;

a supply of electrolyte between said fixed and orbiting scroll members;

a source of electric current applying electric current through said electrolyte between said fixed scroll member and said orbiting scroll member; and

driving means for orbiting said orbiting scroll member relative said fixed scroll member during the application of said current to enable electrochemical machining of the fixed and orbiting scroll members.

12. The apparatus of claim 11 in which said mechanisms holding said scroll members including associated scroll wraps holds said scroll member in a spaced relationship apart so that the minimum clearance space between said scroll wraps is substantially equal to the clearance space between each said wrap and its opposing scroll member.

13. The apparatus of claim 11 in which said drive means orbits said orbiting scroll member in a short stroke whereby radial contact between said scroll members is prevented.