Scroll pump having bellows providing angular synchronization and back-up system for bellows

Patent metadata

Field	Value
Publication number	US-9404491-B2
Application number	US-201313798613-A
Country	US
Kind code	B2
Filing date	Mar 13, 2013
Priority date	Mar 13, 2013
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A scroll pump has a metallic bellows that angularly synchronizes the stationary and orbiting scroll blades of the pump, and a hack-up system for the bellows. The back-up system consists of pins integral with and fixed relative to one of the stationary and orbital parts of the scroll pump, and a guide part that is integral with and fixed relative to the other of the stationary and orbital parts. The back-up system may be a non-contacting hack-up system in which there is no contact between the pins and guide part during normal operation of the pump. Therefore, no particles are created by a wearing away of such parts which would otherwise have the potential to contaminate the fluid being worked by the pump and reduce the useful life of the pump.

First claim

What is claimed is:

1. A scroll pump comprising:
a frame;
a stationary plate scroll fixed to the frame and comprising a stationary scroll blade centered about a longitudinal axis of the scroll pump, wherein the frame and the stationary plate scroll are a stationary part of the scroll pump;
an orbiting plate scroll comprising an orbiting scroll blade juxtaposed with the stationary scroll blade in a radial direction of the scroll pump such that the stationary scroll blade and the orbiting scroll blade are nested;
an eccentric drive mechanism supported by the frame and operatively connected to the orbiting scroll blade so as to cause the orbiting scroll blade to orbit about the longitudinal axis of the scroll pump, and wherein the eccentric drive mechanism supports the orbiting scroll blade so as to be rotatable about a second axis that is parallel to the longitudinal axis of the scroll pump, wherein the orbiting plate scroll is an orbital part of the scroll pump;
a metallic bellows comprising a first end and a second end, the metallic bellows being fixed at the second end to the frame, and the orbiting scroll blade being fixed to the metallic bellows at the first end such that the metallic bellows angularly synchronizes the orbiting scroll blade and the stationary scroll blade; and
a non-contacting back-up system comprising a plurality of pins extending axially in directions parallel to the longitudinal axis of the scroll pump from one of the stationary and orbital parts of the scroll pump, and a guide part fixed relative to the other of the stationary and orbital parts of the scroll pump, the guide part comprising a plurality of surfaces defining a plurality of respective openings extending axially in the directions parallel to the longitudinal axis of the scroll pump, wherein:
each of the plurality of pins extends axially into a respective one of the openings, and
each of the plurality of pins is spaced in its entirety from the other of the stationary and orbital parts of the scroll pump such that a radial clearance exists between each pin of the plurality of pins and each respective surface.

2. The scroll pump as claimed in claim 1 , wherein, for each pin of the plurality of pins and the respective opening of the plurality of openings into which the pin extends, a geometric axial center of the pin is offset from a geometric axial center of the respective opening such that the geometric axial center of the pin traverses an orbit about the geometric axial center of the respective opening as the orbiting scroll blade is being driven by the eccentric drive mechanism.

3. The scroll pump as claimed in claim 2 , wherein, for each pin of the plurality of pins and the respective opening of the plurality of openings into which the pin extends:
the pin has a width, the opening has a width, and the orbit of the geometric center of the pin has a width;
the width of the opening is the sum of the width of the pin, plus the width of the orbit of the geometric center of the pin, plus a predetermined value less than BCD*Tan (MRC/(Pitch/360)),
wherein BCD is the Bolt Circle Diameter of the pin,
MRC is the minimum radial clearance between the stationary scroll blade and the orbiting scroll blade, and
Pitch is the distance in the radial direction between successive wraps of the stationary scroll blade and the orbiting scroll blade.

4. The scroll pump as claimed in claim 1 , wherein the orbiting scroll blade is disposed at a front side of the orbiting plate scroll, each of the plurality of pins is integral with the orbiting plate scroll and extends axially from a back side thereof in a direction away from the orbiting scroll blade, and the guide part is integral with the frame.

5. The scroll pump as claimed in claim 1 , wherein the metallic bellows angularly synchronizes the orbiting scroll blade and the stationary scroll blade in the scroll pump when the load on the orbiting scroll blade is less than a predetermined rated load of the orbiting scroll blade, whereby each of the plurality of pins engages the respective surface of the guide part if the metallic bellows should fail.

6. The scroll pump as claimed in claim 1 , wherein the metallic bellows angularly synchronizes the orbiting scroll blade and the stationary scroll blade in the scroll pump when the scroll pump is operating normally, and each of the plurality of pins only engages the respective surface of the guide part when an abnormal operation of the scroll pump occurs.

7. The scroll pump as claimed in claim 1 , wherein the metallic bellows has a torsional stiffness that suppresses rotation of the orbiting plate scroll about the second axis up to a rated load of the orbiting plate scroll in the scroll pump, and the radial clearance between each of the plurality of pins and the respective surface of the guide part is maintained as long as the load on the orbiting scroll blade is less than a rated load of the scroll pump.

8. A scroll pump comprising:
a scroll blade set comprising a stationary scroll blade fixed in the scroll pump and an orbiting scroll blade juxtaposed with the stationary scroll blade in a radial direction of the scroll pump, wherein the stationary scroll blade and the orbiting scroll blade are nested;
an eccentric drive mechanism operatively connected to the orbiting scroll blade so as to cause the orbiting scroll blade to orbit about a longitudinal axis;
a metallic bellows comprising a first end and a second end, the second end being fixed in the scroll pump, and the orbiting scroll blade being operatively connected to the metallic bellows at the first end such that the metallic bellows angularly synchronizes the orbiting scroll blade and the stationary scroll blade; and
an angular synchronization back-up system for maintaining an angular synchronization between the orbiting scroll blade and the stationary scroll blade in the event that a load on the orbiting scroll blade exceeds a rated load of the scroll pump, wherein:
the angular synchronization back-up system comprises a plurality of pins extending axially in directions parallel to the longitudinal axis, and a guide part in which a plurality of openings open in the directions parallel to the longitudinal axis is defined;
the plurality of pins is fixed relative to one of the stationary and orbiting scroll blades in the scroll pump, the guide part is fixed relative to the other of the stationary and orbiting scroll blades in the scroll pump, and the pins of the plurality of pins extend axially in the directions parallel to the longitudinal axis into the plurality of openings, respectively;
the guide part comprises a plurality of surfaces respectively defining the plurality of openings into which the pins of the plurality of pins respectively extend;
a radial clearance exists in all directions between each pin of the plurality of pins and each respective surface of the plurality of surfaces, as long as the load on the orbiting scroll blade is less than the rated load; and
for each pin of the plurality of pins and the respective opening of the plurality of openings into which the pin extends, a geometric axial center of the pin is offset from a geometric axial center of the respective opening such that the geometric axial center of the pin traverses an orbit about the geometric axial center of the respective opening as the orbiting scroll blade is being driven by the eccentric drive mechanism.

9. The scroll pump as claimed in claim 8 , wherein the metallic bellows angularly synchronizes the orbiting scroll blade and the stationary scroll blade in the scroll pump when the load on the orbiting scroll blade is less than the rated load.

10. The scroll pump as claimed in claim 8 , wherein, for each pin

Assignees

• Agilent Technologies Inc

Inventors

• Forni Ronald J

Classifications

• F04C18/0215 Primary

  where only one member is moving · CPC title

• F04C2/025 Primary

  the moving and the stationary member having co-operating elements in spiral form · CPC title

• F04C25/02

  for producing high vacuum (sealing arrangements F04C27/00; silencing F04C29/06) · CPC title

• F01C17/06 Primary

  using cranks, universal joints or similar elements (F01C1/07 takes precedence) · CPC title