EP-4499984-B1 - SCROLL PUMP

EP4499984B1EP 4499984 B1EP4499984 B1EP 4499984B1EP-4499984-B1

Inventors

SCHOFIELD, NIGEL PAUL
HOLBROOK, ALAN ERNEST KINNAIRD
BEDWELL, DAVID

Dates

Publication Date: 20260506
Application Date: 20230330

Claims (11)

A non-contacting scroll pump (100), the non-contacting scroll pump comprising: a housing (110); an orbiting scroll (130) located within the housing; and a thrust bearing assembly (170) located within the housing for axially supporting the orbiting scroll, wherein the thrust bearing assembly comprises: a first plate (171) fixed to the orbiting scroll; a second plate (172) spaced apart from the first plate; a ball bearing (174) located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and a coupling structure (175) extending between the housing and the second plate to couple the housing to the second plate, wherein the second plate comprises a recess (172a) and an end (175b) of the coupling structure is located within the recess, and wherein the coupling structure is engaged with the second plate such that the second plate is rotatable relative to the coupling structure.
The non-contacting scroll pump (100) of claim 1, wherein the coupling structure is a pin (175).
The non-contacting scroll pump (100) of any preceding claim, further comprising: a first ball bearing cage (173a) sandwiched between the first plate and the second plate; and a second ball bearing cage (173b) sandwiched between the first plate and the second plate, wherein the first and second ball bearing cages house the ball bearing to constrain movement of the ball bearing.
The non-contacting scroll pump (100) of claim 3, wherein the first ball bearing cage is fixed to the first plate and the second ball bearing cage is fixed to the second plate.
The non-contacting scroll pump (100) of claim 3 or 4, wherein the first and second ball bearing cages each comprise a hole, the hole of the first ball bearing cage overlapping with the hole of the second ball bearing cage, and wherein the ball bearing is accommodated within the overlapped holes of the ball bearing cages.
The non-contacting scroll pump (100) of any preceding claim, wherein the end of the coupling structure and the recess of the second plate together form a ball and socket joint.
The non-contacting scroll pump (100) of claim 6, wherein the end of the coupling structure has a rounded surface and the recess is tapered.
The non-contacting scroll pump (100) of any preceding claim, wherein the non-contacting scroll pump comprises three of the thrust bearing assemblies of claim 1, wherein each of the three thrust bearing assemblies comprises: a first plate fixed to the orbiting scroll; a second plate spaced apart from the first plate; a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the second plate comprises a recess and an end of the coupling structure is located within the recess, and wherein the coupling structure is engaged with the second plate such that the second plate is rotatable relative to the coupling structure, wherein the three thrust bearing assemblies are evenly angularly distributed around the rotation axis of the orbiting scroll in a triangular formation.
The non-contacting scroll pump (100) of any preceding claim, wherein the coupling structure is for adjusting the axial position of the orbiting scroll.
A vacuum pumping system comprising a plurality of vacuum pumps, wherein one of the vacuum pumps is the non-contacting scroll pump of any preceding claim.
Use of the non-contacting scroll pump of any of claims 1 to 9 to pump fluid.

Description

FIELD OF THE INVENTION The present invention relates to scroll pumps. BACKGROUND Scroll pumps are a known type of pump used in various different industries to pump fluid. Scroll pumps operate by using the relative motion of two intermeshed scrolls (known as a fixed scroll and an orbiting scroll) to pump fluid. Each of the fixed and orbiting scrolls includes a spiral wall extending from a base. One type of scroll pump is a non-contacting scroll pump. In a non-contacting scroll pump, there is no contact between the tip (i.e. the end of the spiral wall) of each of the fixed and orbiting scrolls and the other scroll. Furthermore, in a non-contacting scroll pump, there is no tip seal between the tip of each of the fixed and orbiting scrolls and the other scroll. Therefore, in non-contacting scrolls pumps, there is a small gap (or clearance), e.g. of 10-20 microns, between the tip of each of the fixed and orbiting scrolls and the other scroll. In order to maintain said gap, non-contacting scroll pumps typically include a thrust bearing assembly engaged with one of the scrolls to keep the scroll in the correct axial position relative to the other scroll. JPH11280673A discloses a non-contacting scroll pump comprising a thrust bearing assembly located within the housing of the pump for axially supporting the orbiting scroll, wherein the thrust bearing assembly comprises a first and a second load receiving portion formed in a circular plate shape with spherical bodies provided in-between. An advancing/ retreating mechanism is provided which comes into contact with one of the load receiving portion through a movable mechanism. GB2595283A and WO2017/220961A1 disclose other examples of non-contacting scroll pump. SUMMARY OF INVENTION In an aspect of the invention, there is provided a non-contacting scroll pump, the non-contacting scroll pump comprising a housing, an orbiting scroll located within the housing, and a thrust bearing assembly located within the housing for axially supporting the orbiting scroll. The thrust bearing assembly comprises a first plate fixed to the orbiting scroll, a second plate spaced apart from the first plate, and a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll. The thrust bearing assembly further comprises a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure is engaged with the second plate such that the second plate is rotatable relative to the coupling structure. The coupling structure may be a pin. According to the invention, the second plate comprises a recess and an end of the coupling structure is located within the recess. The non-contacting scroll pump may further comprise a first ball bearing cage sandwiched between the first plate and the second plate, and a second ball bearing cage sandwiched between the first plate and the second plate, wherein the first and second ball bearing cages house the ball bearing to constrain movement of the ball bearing. The first ball bearing cage may be fixed to the first plate and the second ball bearing cage may be fixed to the second plate. The first and second ball bearing cages may each comprise a hole, the hole of the first ball bearing cage overlapping with the hole of the second ball bearing cage, and wherein the ball bearing is accommodated within the overlapped holes of the ball bearing cages. The end of the coupling structure and the recess of the second plate may together form a ball and socket joint. The end of the coupling structure may have a rounded surface and the recess may be tapered. The non-contacting scroll pump may comprise three thrust bearing assemblies. Each of the three thrust bearing assemblies comprises a first plate fixed to the orbiting scroll, a second plate spaced apart from the first plate, and a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll. Each of the three thrust bearing assemblies further comprises a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure is engaged with the second plate such that the second plate is rotatable relative to the coupling structure. The three thrust bearing assemblies may be evenly angularly distributed around the rotation axis of the orbiting scroll in a triangular formation. The coupling structure may be for adjusting the axial position of the orbiting scroll. In another aspect of the invention, there is provided a vacuum pumping system comprising a plurality of vacuum pumps, wherein one of the vacuum pumps is the non-contacting scroll pump of the above aspect. In yet another aspect of the invention, there is provided the use of the