SLIDER BLOCK RADIAL COMPLIANCE MECHANISM

Abstract: A slider block radial compliance mechanism includes a slider block (20) and a bearing seat (24) which form a subassembly and are located in a circular counterbore in the crankshaft (30). The slider block (20) has a bore which received the boss (12-2) of an orbiting scroll (12). The orbiting scroll (12) and its boss (12-2) are held to an orbiting motion while the slider block (20), bearing seat (24) and crankshaft (30) rotates as a unit with respect to the boss (12-2).

Description: The present invention relates to a slider block radial compliance mechanism. In a scroll compressor the trapped volumes are in the shape of lunettes and are defined between the wraps or elements of the fixed and orbiting scrolls and their end plates. The ends of the lunettes define points of tangency or contact between the wraps of the fixed and orbiting scrolls. These points of tangency or contact are transient in that they are continuously moving towards the center of the wraps as the trapped volumes continue to reduce in size until they are exposed to the outlet port. These points of tangency or contact represent points of wear and leakage so it is desirable to permit outward radial movement of the orbiting scroll to maintain sealing contact of its wrap with that of the fixed scroll. Further, because the trapped volume may contain a liquid slug of refrigerant and/or oil it is desirable to permit inward radial movement of the orbiting scroll to permit leakage from the trapped volume(s) to relieve any excessive buildup of pressure. One approach has been to use an eccentric bushing mechanism to provide the connection between the crankshaft and the orbiting scroll. Another approach has been to use a swing link connection between the orbiting scroll and crankshaft. A slider block radial compliance device is briefly mentioned in US-A-3,924,977. In this patent, the centrifugal force of the orbiting scroll is used to activate the mechanism. The line of movement of the orbiting scroll is along the centrifugal force, i.e. along the line extending from the center of gravity of the counterweight through the center of the crankshaft to the center of the orbiting scroll. A slider block mechanism according to the preamble of claim 1 is known from US-A-3 924 977. The present invention is directed to an improved slider block radial compliance mechanism. The radial compliance mechanism of the invention according to the characterizing part of claim 1 consists of a round counterbore in the end of the eccentric shaft and a subassembly located in the counterbore, the subassembly being made up of a bearing seat and a slider block. The slider block has an eccentric bore for receiving the boss of the orbiting scroll and has a segment of a cylindrical surface circumferentially extending for at least 180°, in the preferred embodiment, and having at least one flat. The bearing seat includes a generally circular portion received in and covering the bottom of the counterbore and an axially extending portion having a first portion complementary to the flat of the slider block and a second portion complementary to said counterbore. Basically, the bearing seat and slider block rotate with the eccentric shaft and with respect to the boss of the orbiting scroll which is carried through an orbiting path relative to the axis of rotation of the eccentric shaft. Some movement of the slider block is possible within the counterbore with the movement being in the nature of a sliding motion of the slider block while engaging the generally cylindrical portion and the complementary flat portion of the bearing seat. The amount of movement permitted will generally be on the order of 0.13 to 0.25 cm (.05 to 0.1 inches). Figure 1 is a vertical sectional view of a portion of a scroll compressor employing the slider block mechanism of the present invention and corresponds to a section taken through 1-1 of Figure 2; Figure 2 is a sectional view of the slider block mechanism taken along line 2-2 of Figure 1; Figure 3 is a top view of the slider block; Figure 4 is a top view of the bearing seat; and Figure 5 is an unsectioned top view corresponding to Figure 2 and with the orbiting scroll structure removed. In Figure 1, the numeral 10 generally indicates a scroll compressor which is only partially illustrated. Scroll compressor 10 includes an orbiting scroll 12 with a wrap 12-1 and a fixed scroll 14 with a wrap 14-1. Orbiting scroll 12 has a boss 12-2 which is received in bore 20-1 of slider block 20. The line B-B represents the center of orbiting scroll as well as the axis of bore 20-1. Referring specifically to Figure 3, the slider block 20 includes a flat 20-2 and the axis B-B of bore 20-1 appears as point B. Referring now to Figure 4, bearing seat 24 is made of molded polyphenylene sulfide containing 30% glass fiber and 15% polytetrafluorethylene which has a small coefficient of friction and has a flat circular portion 24-1, an axially extending portion 24-2 having a flat 24-3, a radially extending portion 24-4 and an eccentric bore 24-5 in circular portion 24-1. As is best shown in Figures 2 and 5, slider block 20 and bearing seat 24 are received in counterbore 30-1 of crankshaft 30 as a subassembly with slider block 20 located between circular portion 24-1 and radially extending portion 24-4 such that flat 20-2 can engage flat 24-3. Radially extending portion 24-4 prevents relative axial movement of the slider block 20 in the subassembly. After the slider block 20 and bearing seat 24 are placed in counterbore 30-1, bearing seat 24 is fixed relative to crankshaft 30 by screw or pin 26 which extends through bore 30-2 into bore 24-6. As a result, bearing seat 24 rotates with crankshaft 30 as a unit. A reciprocating motion of slider block 20 in counterbore 30-1 is the only significant relative motion of slider block 20 with respect to bearing seat 24 and crankshaft 30 during operation and this movement is generally on the order of 0.13 to 0.26 cm(.05 to 0.1 inches), at most. Specifically, slider block 20 is supported on the low friction circular portion 24-1 so that flat 20-2 engages flat 24-3 such that flats 20-2 and 24-3 are parallel to a plane defined by axes A-A and B-B which appear as points A and B, respectively, in Figure 5. During operation, as crankshaft 30, counterweight 32, bearing seat 24 and slider block 20 rotate together about A-A the axis of crankshaft 30, centrifugal force acts on slider block 20 causing it to move radially outward in counterbore 30-1 relative to A-A and along the plane defined by axes A-A and B-B. The engagement of flats 20-2 and 24-3 which are parallel to the plane defined by A-A and B-B coupled with the low friction surface of flat 24-3 facilitates movement of slider block 20 since little or no oil will reach the surface between flats 20-2 and 24-3. As slider block 20 moves, it carries boss 12-2 and, therefore, orbiting scroll 12 with it. Subject to the movement of slider block 20 due to centrifugal force and the gas forces acting on wrap 12-1 and any movement due to overriding a liquid slug or the like, slider block 20 generally moves as a unit with bearing seat 24 and crankshaft 30. As crankshaft 30 rotates, oil from the sump (not illustrated) is forced into eccentric generally axial bore 30-3 which acts as a centrifugal pump. The pumped lubricant passes into counterbore 30-1, through bore 24-5 and through axial groove 20-3 where it lubricates boss 12-2. While crankshaft 30, bearing seat 24 and slider block 20 are rotating, boss 12-2 and orbiting scroll are held to an orbiting motion by Oldham ring 28. As a result, groove 20-3 traverses the cylindrical surface of boss 12-2 providing lubrication thereto. Lubricant supplied to counterbore 30-1 also is directed via bore 30-4 to provide lubrication to the bearings 34 and orbiting scroll 12. From the foregoing, it should be clear that the present invention facilitates manufacture by permitting the use of circular counterbore 30-1 and facilitates assembly by permitting the slider block 20 and bearing seat 24 to be inserted in counterbore 30-1 as a unit. Further, bearing seat 24 can be molded or extruded to shape.

Claims: A slider block radial compliance mechanism in a scroll compressor means (10) having an orbiting scroll means (12) having an axis (B-B), a fixed scroll means (14), crankshaft means (30) having a first and a second end and adapted to rotate about an axis (A-A) of said crankshaft means (30), said slider block radial compliance mechanism comprising: a recess means (30-1) formed in said first end of said crankshaft means (30), and slider block means (20) located in said recess means (30-1), said slider block means (20) and said orbiting scroll means (12) coacting to permit relative rotary motion of said axis (B-B) of said orbiting scroll means (12) about said axis (A-A) of said crankshaft means (30) so that said orbiting scroll means (12) is moved with said slider block means (20) when said slider block means (20) moves in relative reciprocating movement in said recess means (30-1), characterized in that said recess means (30-1) is circular in shape, and in further comprising bearing seat means (24) fixedly located in said circular recess means (30-1) and having a flat circular portion (24-1) and an axially extending portion (24-2), said circular recess means (30-1) and said bearing seat means (24) coacting with said slider block means (20) to limit movement of said slider block means (20) to substantially only relative reciprocating movement of said slider block means (20) with respect to said bearing seat means (24). The radial compliance mechanism of claim 1, characterized in that said slider block means (20) forms a portion of a cylinder with said cylinder having a slightly smaller diameter than said circular recess means (30-1), and said axially extending portion (24-2) and said slider block means (20) each has a flat (20-2, 24-3) with said flats coacting to permit said relative reciprocating movement of said slider block means (20). The radial compliance mechanism of claim 1, characterized in that said axially extending portion (24-2) extends from said flat circular portion (24-1) to a radially extending portion (24-4) which overlies said slider block means (20) to limit axial movement of said slider block means (20), and said axially extending portion (24-2) and said slider block means (20) each has a flat (20-2, 24-3) with said flats coacting to permit said relative reciprocating movement of said slider block means (20).

Inventors: FRASER, HOWARD HENRY, JR., GRUNWALD, STEFAN HUBERT
Applicants: CARRIER CORPORATION
Application year: 1990
Main classification: F04C29
IPC codes: F04C23, F04C18, F04C29