U.S. patent application number 10/578989 was filed with the patent office on 2007-04-12 for multi-stage friction vacuum pump.
Invention is credited to Heinrich Englander.
Application Number | 20070081889 10/578989 |
Document ID | / |
Family ID | 34559626 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070081889 |
Kind Code |
A1 |
Englander; Heinrich |
April 12, 2007 |
Multi-stage friction vacuum pump
Abstract
A multi-stage vacuum pump includes at least one turbo-compressor
stage (11) and is equipped with a circular compressor stage (33) on
the pressure side of the turbo-compressor stage. The pump has small
axial dimensions, enabling the compression to be increased without
significantly increasing the space requirement.
Inventors: |
Englander; Heinrich;
(Linnich, DE) |
Correspondence
Address: |
Fay Sharpe Fagan Minnich & McKee
1100 Superior Avenue
Seventh Floor
Cleveland
OH
44114-2579
US
|
Family ID: |
34559626 |
Appl. No.: |
10/578989 |
Filed: |
October 28, 2004 |
PCT Filed: |
October 28, 2004 |
PCT NO: |
PCT/EP04/12196 |
371 Date: |
May 11, 2006 |
Current U.S.
Class: |
415/90 |
Current CPC
Class: |
F04D 17/02 20130101;
F04D 19/046 20130101; F04D 17/168 20130101; F04D 17/127
20130101 |
Class at
Publication: |
415/090 |
International
Class: |
F01D 1/36 20060101
F01D001/36 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2003 |
DE |
103 53 034.7 |
Claims
1. A multi-stage friction vacuum pump comprising: at least one
axially compressing turbo-compressor stage with a rotor rotating
about its axis and having rotor discs projecting between stationary
stator discs; a radially compressing circular compressor stage
arranged on the compressor side of the turbo-compressor stage, said
circular compressor stage comprising a rotor having axially
projecting rotor blades arranged on circular paths and a stator
having axially projecting stator blades arranged on circular paths,
the stator blades engaging in radial gaps between adjacent circular
paths of rotor blades.
2. The friction vacuum pump of claim 1, wherein the rotor blades of
the circular compressor stage are arranged on a rotor body of the
turbo-compressor stage carrying the rotor discs.
3. The friction vacuum pump of claim 1, wherein the stator blades
are arranged on a stator body of the turbo-compressor stage
carrying the stator discs.
4. The friction vacuum pump of claim 1, as a multi-inlet pump,
further including: at least two axially spaced, serially
compressing turbo-compressor stages between which an intermediate
inlet is situated, and a circular compressor stage on the
compressor side of the first turbo-compressor stage.
5. The friction vacuum pump of claim 1, as a multi-inlet pump,
further including: at least two axially spaced, serially
compressing turbo-compressor stages between which an intermediate
inlet is situated, and a circular compressor stage on the
compressor side of the second turbo-compressor stage.
6. The friction vacuum pump of claim 1, wherein the circular
compressor stage compresses radially inward.
7. The friction vacuum pump of claim 1, wherein in that the
circular compressor stage is designed with at least two stages and
alternately compresses one of radially inward and radially
outward.
8. The friction vacuum pump of claim 1, wherein the rotor blades
have an axial length that tapers in a direction of compression.
Description
BACKGROUND
[0001] The invention refers to a multi-stage friction vacuum pump
with at least one axially compressing turbo-compressor stage having
a rotor rotating about its axis and comprising rotor discs
projecting between stationary stator discs.
[0002] Turbomolecular pumps belong in the group of friction vacuum
pumps with which a high vacuum can be created, for example for
recipients used in semi-conductor manufacturing or for mass
spectrometers. A multi-stage friction vacuum pump described in U.S.
Pat. No. 7,011,491 comprises one or a plurality of turbo-compressor
stages each formed by a rotor with radially projecting rotor discs
and a stator with radially projecting stator discs. The rotor discs
and the stator discs mesh in a comb-like manner with little space
between them. They cause a molecular flow axial to the rotor axis.
In addition to the turbo-compressor stage, a circular compressor
stage may be provided which comprises a rotor with axially
projecting rotor blades arranged on a circular line and a stator
with axially protruding stator blades arranged on a circular line.
The rotor blades and the stator blades mesh alternately and cause a
molecular flow that is directed either radially inward or radially
outward, depending on the sense of rotation and the angle of attack
of the blades.
[0003] It is the object of the invention to provide a multi-stage
friction vacuum pump with at least one turbo-compressor stage,
wherein the stages are arranged in series in the flow path and
which is to yield higher compression.
SUMMARY
[0004] The vacuum pump comprises a turbo-compressor stage and a
circular compressor stage arranged downstream in the flow path.
Whereas the turbo-compressor stage is suited to generate a high
vacuum, the downstream circular compressor stage serves to effect a
pressure increase. As a consequence, since the gas volume is
reduced by compression, the circular compressor stage can have
small dimensions. The circular compressor stage has a small axial
dimension since it is flown through mainly in the radial direction.
The overall dimensions of the friction pump are not significantly
increased by the circular compressor stage, but the compression is
clearly intensified with respect to single-stage friction vacuum
pumps. The present combination of an upstream turbo-compressor
stage and a downstream circular compressor stage offers the
advantage of requiring little space while having a high compression
capacity.
[0005] According to a preferred embodiment of the invention, the
turbo-compressor stage and the circular compressor stage are
integrated in a common combination of rotor and stator. This means
that the rotors of both compressor stages are formed by a single
combined rotor and the stators of both compressor stages are also
formed by a single combined stator. Thus, the dimensions and the
weight can be reduced further.
[0006] The present friction vacuum pump is preferably designed as a
multiple inlet pump. It comprises at least two axially spaced,
serially compressing turbo-compressor stages between which an
intermediate inlet is located. A circular compressor stage is
arranged on the compressor side of the first turbo-compressor stage
and/or the second turbo-compressor stage. Such a pump is
particularly suited for use in the context of mass spectrometers.
Due to the increased gas flow at the intermediate inlet to which
the analyzing means of the mass spectrometer is connected, the gas
flow at the intermediate inlet is increased without a negative
effect on the pressure at the high vacuum inlet. The increase in
the gas flow at the intermediate inlet means an increased
sensitivity of the mass spectrometer.
[0007] Depending on the compression ratio, different types and
structures may be used for the circular compressor stages, such as
described in U.S. Pat. No. 7,011,491.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The following is a detailed description of embodiments of
the invention with reference to the drawings. These embodiments
should not be seen as limiting the scope of protection of the
present invention. Rather, this scope is defined by the claims and
the equivalents thereof.
[0009] In the Figures:
[0010] FIG. 1 illustrates a longitudinal section through a friction
vacuum pump of the present invention,
[0011] FIG. 2 is an illustration of the circular compressor
stage,
[0012] FIGS. 3 and 4 are longitudinal sections through different
embodiments of circular compressor stages.
DETAILED DESCRIPTION
[0013] The friction vacuum pump illustrated in FIG. 1 comprises a
housing 10 of substantially cylindrical design, which has a high
vacuum port HV at one end. In the housing wall an intermediate
inlet ZE1 is provided that is open to the side. The intermediate
inlet ZE1 is bridged by webs 18 that connect the stator parts with
each other.
[0014] In the front portion 10a of the housing 10, a first
turbo-compressor stage 11 formed by a stator 12 and a rotor 13 is
arranged. The stator 12 has a plurality of stator discs 15 directed
radially inward from a circumferential wall 14. The rotor 13 has a
plurality of rotor discs 16 projecting radially outward between the
stator discs 15. A drive 17 including a fast rotating electric
motor drives the rotor 13 at a number of rotations between 30,000
and 60,000 rpm.
[0015] A second turbo-compressor stage 21 is arranged on the
compressor side of the first turbo-compressor stage 11 and has its
inlet connected with the intermediate inlet ZE1. The
turbo-compressor stage 21 is formed by a stator 22 and a rotor 23.
The stator 22 comprises a plurality of stator discs 25 directed
radially inward from a circumferential wall 22. The rotor 23
comprises a plurality of rotor discs 26 projecting radially outward
between the stator discs 25. The rotors 13 and 23 are fixedly
interconnected and are driven together by the drive 17.
[0016] In the housing 10, a further compressor stage 30 follows the
second turbo-compressor stage 21, this further compressor stage
being additionally connected with an intermediate inlet ZE2. For
example, the compressor stage 30 is a Holweck stage or another
molecular pump, for example a Gaede pump, a Siegbahn pump, an
Englander pump or a side channel pump.
[0017] In the present embodiment, a circular compressor stage 33 is
provided following the first turbo-compressor stage 11. It
comprises a rotor disc 34 which is a part of the rotor 13 of the
turbo-compressor stage 11, and a stator disc 32 which is a part of
the stator 12. The rotor disc 34 comprises rotor blades 35 arranged
on concentric circles, and the stator disc 32 comprises stator
blades 36 also arranged on concentric circles and engaging in gaps
between the rotor circles, as is illustrated in FIG. 2. The stator
blades and the rotor blades are inclined oppositely with respect to
the radial direction. Depending on the sense of rotation of the
rotor, the circular compressor stage 33 conveys either radially
outward or radially inward. In the present embodiment, the
conveying direction is indicated by the arrow 37. The gas transport
passes from the high vacuum inlet HV through the turbo-compressor
stage 11 and radially inward from the circumference thereof through
the circular compressor stage 33 and from there through a gap 38 to
the intermediate inlet ZE1. From the intermediate inlet ZE1, the
turbo-compressor stage 21 conveys the gas to the compressor stage
30. The second intermediate inlet ZE2 also opens into the
compressor stage 30. The compressor stage 30 conveys to an outlet
(not illustrated).
[0018] One of the rotor discs 16 of the turbo compressor stage 11
is the supporting disc for the rotor blades of the circular
compressor stage 33. The stator disc of the circular compressor
disc simultaneously forms the end wall of the pressure-side end of
the turbo-compressor stage 11.
[0019] It is a special advantage that the circular compressor stage
33 is quasi integrated in the turbo-compressor stage 11. The only
additional effort required are the rotor and stator blades 35, 36
additionally provided at the rotor and the stator of the turbo
compressor stage.
[0020] As an alternative to the present embodiment, a circular
compressor stage 33 may also be provided behind the second
turbo-compressor stage 21. The circular compressor stage arranged
on the pressure side of the respective turbo-compressor stage and
integrated in the turbo-compressor stage increases the gas flow on
the pressure side. For a mass spectrometer connected thereto, this
means an increase in sensitivity.
[0021] FIG. 3 illustrates the gas flow 40 through the circular
compressor stage 33 flowing radially from the outside inward.
[0022] In the embodiment of FIG. 4, the blade surface of the rotor
disc 34 is conical. The rotor blades 35 have an axial length that
decreases as the radius of the circular path decreases.
[0023] It is also possible to use a circular compressor stage with
a plurality of discs and alternately outward and inward directed
flow paths, as is generally illustrated in FIG. 7 of U.S. Pat. No.
7,011,491.
[0024] The invention has been described with reference to the
preferred embodiments. Modifications and alterations may occur to
others upon reading and understanding the preceding detailed
description. It is intended that the invention be constructed as
including all such modifications and alterations insofar as they
come within the scope of the appended claims or the equivalents
thereof.
* * * * *