Scroll pump with floating motor coupler

Abstract

A scroll pump includes first and second scroll members connected together by a plurality of idler assemblies configured to allow the second scroll member to move in an orbital path with respect to the first scroll member. A rotary bearing is connected to an end plate of the orbiting scroll member. A motor and motor coupler are coupled to the rotary bearing to move the bearing in an orbital path corresponding to the orbital path followed by the second scroll member. The rotary bearing may roll freely within the coupler.

1 . A scroll pump comprising:
 a pump housing;   a fixed scroll member fixedly connected to the pump housing;   an orbiting scroll member floatingly contained within the pump housing and in orbiting engagement with the fixed scroll member;   a rotary bearing rotatingly connected to the orbiting scroll member, the rotary bearing having a radius and diameter and an axis of rotation;   a motor fixedly connected to the housing, the motor comprising a motor shaft, the motor shaft having an axis of rotation parallel to and radially offset from the axis of rotation of the rotary bearing; and   a coupler fixedly connected to the motor shaft and operably engaged with the rotary bearing;   wherein the coupler comprises a sidewall having an inner surface, the inner surface of the coupler engaged with a corresponding bearing surface of the rotary bearing;   wherein the rotary bearing is unconstrained by the coupler in at least one direction perpendicular to the axis of rotation of the motor shaft;   wherein rotation of the coupler causes the rotary bearing and the orbiting scroll member to orbit with respect to the fixed scroll member.   
     
     
         2 . The scroll pump of  claim 1  wherein the inner surface of the coupler includes a first bearing surface and a second bearing surface spaced from the first bearing surface. 
     
     
         3 . The scroll pump of  claim 1  wherein the inner surface of the coupler includes a third bearing surface extending in a direction from the first bearing surface to the second bearing surface. 
     
     
         4 . The scroll pump of  claim 3  wherein the inner surface of the coupler further comprises a third bearing surface extending between the first bearing surface and the second bearing surface and connecting the first bearing surface to the second bearing surface. 
     
     
         5 . The scroll pump of  claim 4  wherein the first bearing surface, the second bearing surface, and the third bearing surface are connected together by at least one curvilinear connecting surface. 
     
     
         6 . The scroll pump of  claim 4  wherein the at least one curvilinear connecting surface has a radius nominally equal to the diameter of the rotary bearing. 
     
     
         7 . The scroll pump of  claim 4  wherein the first bearing surface is parallel to a tangent of the rotary bearing, and wherein the second bearing surface is parallel to the first bearing surface. 
     
     
         8 . The scroll pump of  claim 7  wherein the third bearing surface is perpendicular to at least one of the first bearing surface and the second bearing surface. 
     
     
         9 . The scroll pump of  claim 7  wherein the third bearing surface is perpendicular to the first bearing surface and the second bearing surface. 
     
     
         10 . The scroll pump of  claim 7  wherein the third bearing surface is oriented with respect to the first bearing surface at a first included angle of greater than 90 degrees and the second bearing surface is oriented with respect to the first bearing surface at a second included angle of less than 90 degrees. 
     
     
         11 . The scroll pump of  claim 7  wherein a perpendicular distance between the first bearing surface of the coupler and the second bearing surface of the coupler is nominally greater than the diameter of the rotary bearing so that the rotary bearing is free to roll on the first bearing surface and the second bearing surface. 
     
     
         12 . The scroll pump of  claim 1  wherein the coupler is weighted to counteract unbalanced centrifugal forces imparted thereto by the orbiting scroll during operation of the scroll pump. 
     
     
         13 . A method of assembling a scroll pump, comprising:
 providing a first scroll member having a first end plate and a first involute extending from the first involute;   providing a second scroll member having a second end plate and a second involute extending from the second involute;   providing a plurality of idler camshafts, each having a first shaft portion and a second shaft portion;   fitting the first shaft portions of the idler camshafts to the first scroll member;   axially fixing the first shaft portions of the idler camshafts to the first scroll member;   providing a shim having a thickness corresponding to a predetermined clearance between the first end plate and the second involute;   fitting the second scroll member to the first scroll member with the first end plate adjacent the second involute and the second end plate adjacent the first involute;   fitting the shim between the first scroll member and the second scroll member to set the predetermined clearance between the first end plate and the second involute;   fitting the second shaft portions of the idler camshafts to the second scroll member;   axially fixing the second shaft portions of the idler camshafts to the second scroll member by expanding an end of the idler camshaft against a bearing connected and axially fixed to the second scroll member.   
     
     
         14 . The method of  claim 13  further comprising removing the shims. 
     
     
         15 . The method of  claim 14  wherein the step of fixing the idler assembly axially to the second scroll member comprises removably fixing the idler assembly axially to the second scroll member. 
     
     
         16 . The method of  claim 14  wherein the step of fixing the idler assembly axially to the second scroll member comprises permanently fixing the idler assembly axially to the second scroll member. 
     
     
         17 . A method of assembling a scroll pump, comprising:
 providing a first scroll member having a first end plate and a first involute extending from the first involute;   providing a second scroll member having a second end plate and a second involute extending from the second involute;   providing a plurality of idler camshafts, each having a first shaft portion and a second shaft portion;   fitting the first shaft portions of the idler camshafts to the first scroll member;   axially fixing the first shaft portions of the idler camshafts to the first scroll member;   fitting the second scroll member to the first scroll member with the first end plate adjacent the second involute and the second end plate adjacent the first involute with a predetermined clearance between the first end plate and the second involute;   fitting the second shaft portions of the idler camshafts to the second scroll member;   axially fixing the second shaft portions of the idler camshafts to the second scroll member by expanding an end of the idler camshaft against a bearing connected and axially fixed to the second scroll member.   
     
     
         18 . The method of  claim 17  further comprising:
 providing a fixture configured to hold the first scroll member and the second scroll member with the predetermined clearance between the first end plate and the second involute; and 
 fitting the first scroll member in the fixture; and 
 fitting the second scroll member in the fixture with the predetermined clearance between the first end plate and the second involute.