U.S. patent application number 12/675219 was filed with the patent office on 2010-12-02 for current leadthrough for a vacuum pump.
This patent application is currently assigned to OERLIKON LEYBOLD VACUUM GMBH. Invention is credited to Heinrich Englaender.
Application Number | 20100303650 12/675219 |
Document ID | / |
Family ID | 40091786 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100303650 |
Kind Code |
A1 |
Englaender; Heinrich |
December 2, 2010 |
CURRENT LEADTHROUGH FOR A VACUUM PUMP
Abstract
The vacuum pump comprises a casing (10) closed by a vacuum cover
(20). Between an end wall (14) of the casing (10) and the vacuum
cover (20), a circuit board (16) is arranged for current
feedthrough. The circuit board (16) is sealed by two sealing
elements (15, 21) of different diameters so that an annular partial
region (22) is on its outer side subjected to the atmospheric
pressure and is on its inner side subjected to the vacuum. It is
avoided that the circuit board (16) laterally projects beyond the
contour of the casing (10).
Inventors: |
Englaender; Heinrich;
(Linnich, DE) |
Correspondence
Address: |
FAY SHARPE LLP
1228 Euclid Avenue, 5th Floor, The Halle Building
Cleveland
OH
44115
US
|
Assignee: |
OERLIKON LEYBOLD VACUUM
GMBH
KOELN
DE
|
Family ID: |
40091786 |
Appl. No.: |
12/675219 |
Filed: |
August 28, 2008 |
PCT Filed: |
August 28, 2008 |
PCT NO: |
PCT/EP2008/061335 |
371 Date: |
February 25, 2010 |
Current U.S.
Class: |
417/422 ;
417/423.4 |
Current CPC
Class: |
F04D 19/042 20130101;
F04D 17/168 20130101; F04D 29/083 20130101; F04D 25/0693
20130101 |
Class at
Publication: |
417/422 ;
417/423.4 |
International
Class: |
F04D 29/08 20060101
F04D029/08; F04D 19/04 20060101 F04D019/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2007 |
DE |
20 2007 012 070.2 |
Claims
1. A vacuum pump comprising a vacuum-tight casing, said casing
accommodating a motor and a pump rotor and being provided with a
pump inlet and a pump outlet, said pump further comprising a
current feedthrough, said current feedthrough including a circuit
board, an inner side of said circuit board being arranged in
abutment on an end face of the wall of the casing with
interposition of a first sealing means, and an outer side of said
circuit board being arranged in abutment on a vacuum cover of the
casing with interposition of a second sealing means, wherein said
first and second sealing means are arranged with a lateral
displacement relative to each other so that a partial region of the
circuit board is on its outer side subjected to atmospheric
pressure and is on its inner side subjected to a generated
vacuum.
2. The vacuum pump according to claim 1, further including external
electric conductors extending from said partial region and
connected to traces of the circuit board.
3. The vacuum pump according to claim 2, wherein said external
conductors are connected to a plug device fastened to the
casing.
4. The vacuum pump according to claim 1, wherein the vacuum cover
is arranged in a protective cover and is movable relative
thereto.
5. The vacuum pump according to claim 4, wherein the protective
cover is provided with a positioning means for positioning the
vacuum cover.
6. The vacuum pump according to claim 1, wherein the circuit board
is formed with an opening for pressure compensation.
7. The vacuum pump according to according to claim 1, wherein the
circuit board carries electrical components on its inner side
and/or its outer side.
8. The vacuum pump according to claim 1, wherein the circuit board
is provided with pump detection electronics.
9. The vacuum pump according to claim 1, wherein the first and
second sealing means are annular sealing elements with different
opening diameters.
10. The vacuum pump according to claim 3, wherein the plug device
is mounted to a protective cover of the casing.
11. The vacuum pump according to claim 3, wherein the first and
second sealing means are first and second O-rings, the first O-ring
being larger in diameter than the second O-ring.
12. The vacuum pump according to claim 5, wherein the positioning
means includes a shoulder of the protective cover.
13. A vacuum pump comprising: a vacuum-tight casing, the casing
holding a motor and a pump rotor and defining a pump inlet and a
pump outlet; a circuit board, an inner side of said circuit board
being arranged in abutment on an end face of the casing, and an
outer side of said circuit board facing away from the end face of
the casing: a vacuum cover covering a portion of the outer side of
the circuit board and defining a hollow space therebetween; a first
annular sealing element disposed between the casing end face and
the circuit based inner side; a second annular sealing element
being disposed between the circuit board outer face and the vacuum
cover, the second annular sealing element being smaller than the
first annular sealing element.
14. The vacuum pump according to claim 13, wherein an opening is
defined in the circuit board such that a pressure in the casing and
a pressure in the hollow space between the vacuum cover and the
circuit board outer side is balanced, such that a region of the
circuit board outer side inside the second annular sealing element
is subject to the pressure in the casing and a region of the
circuit board outside of the second annular sealing element is
subject to atmospheric pressure.
15. The vacuum pump according to claim 14, wherein the pressure in
the casing is a vacuum.
Description
[0001] The present invention relates to a vacuum pump comprising a
vacuum-tight casing accommodating a motor and a pump rotor, and
further comprising a current feedthrough including a circuit
board.
[0002] Vacuum pumps in the form of turbomolecular pumps comprise a
rotor which is configured to rotate at very high rotational numbers
and thus is adapted to generate a high vacuum. In many pumps of
this type, the rotor and the motor for driving the rotor are
supported in magnetic bearings. Within the casing, a vacuum
prevails, usually in the range below 10 mbar. The current
feedthrough devices for the motor and for the vacuum bearings are
provided in a vacuum-tight arrangement on the casing.
[0003] EP 1 757 825 A1 describes a vacuum pump wherein the current
feedthrough into the casing comprises a circuit board. An inner
side of the circuit board is arranged in abutment on the casing
with interposition of a sealing means, and an outer side is
arranged in abutment on an outer vacuum cover with interposition of
a further sealing means, said vacuum cover closing the casing in a
vacuum-tight manner. The traces of the circuit board are guided
through the gap between the two sealing means. The circuit board
comprises a projecting portion arranged externally of the casing
and provided with a connector. A further connector is arranged in
contact with the traces within the casing.
[0004] It is an object of the invention to provide a vacuum pump
wherein the current feedthrough device does not comprise circuit
board portions projecting beyond the casing, thus avoiding the risk
of damage to the circuit board and to exposed plug devices.
[0005] The vacuum pump according to the present invention is
defined by claim 1. Said vacuum pump is provided with a circuit
board having a first sealing means and a second sealing means
arranged thereon, the first sealing means and the second sealing
means being positioned with a lateral displacement relative to each
other so that a partial region of the circuit board is on its outer
side subjected to the atmospheric pressure and is on its inner side
subjected to the generated vacuum.
[0006] An advantage herein resides in that said partial region
which is exposed to a pressure difference and does not laterally
extend beyond the wall of the casing, can be used to connect
electric conductors to the board. Due to the lateral displacement
of the sealing means relative to each other, a space is created
within the wall contour which will be available for connection of
external lines. Consequently, this obviates the need for the
circuit board to extend beyond the outer contour of the casing. In
that wall portion of the circuit board where the pressure
difference is effective, it is the circuit board itself that forms
the wall of the pump. Deflection in this partial region is
prevented because the circuit board is given support by abutment on
the front-side end of the wall of the casing.
[0007] According to a preferred embodiment of the invention, the
vacuum cover forming the vacuum closure of the casing is arranged
within a protective cover and is movable relative thereto. The
possibility of movement vertically to the plane of the cover will
allow for the sealing means to be pressed into position. The vacuum
cover is held in place by the pressure difference acting on it and
is only loosely positioned by the protective cover. The protective
cover serves for avoiding damage to the vacuum cover and the
circuit board. Apart from this function, the protective cover is
useful as a support for a plug connection of the external electric
lines leading to the circuit board. The protective cover includes a
positioning means for positioning the vacuum cover but, on the
other hand, does permit the vacuum cover to undergo reactions to
the existing pressure difference. Alternatively, it is possible to
form the vacuum cover integrally with the protective cover.
[0008] Embodiments of the invention will be explained in greater
detail hereunder with reference to the accompanying drawings.
[0009] FIG. 1 is a partly sectional longitudinal view of the casing
of a vacuum pump, illustrating a first embodiment of the current
feedthrough, and
[0010] FIG. 2 is a view of a second embodiment of the current
feedthrough wherein the circuit board is additionally provided with
electric components.
[0011] In FIG. 1, the casing 10 of a turbomolecular pump is
illustrated. Located within casing 10 are a motor and a pump rotor.
Casing 10 is provided with a pump inlet 11 on one of its ends and
with a pump outlet 12 on its circumference. At said pump inlet 11,
the vacuum is generated. Said pump outlet 12 can lead to the
atmosphere or to a pre-vacuum pump.
[0012] At the rear end of an annular wall 13 of the casing, a
planar end face 14 is arranged. End face 14 is formed with a groove
accommodating an annular first sealing means 15 shaped as an
O-ring. Arranged in abutment on end face 14 is a circuit board 16
consisting of a body of insulating material provided with traces
(not shown) on one or both of its sides. Such circuit boards are
also referred to as "printed circuits". Circuit board 16 is
arranged in sealing abutment on sealing means 15. In the central
area of the circuit board, which is surrounded by end face 14, an
opening 17 is formed in the board for pressure compensation.
Circuit board 16 has an inner side 18 facing towards the interior
chamber of the pump, and an outer side 19 facing away from the
interior chamber. Said inner side 18 is arranged in abutment with
the first sealing means 15.
[0013] A vacuum cover 20 is set against the outer side 19 of the
circuit board. The vacuum cover comprises an annular groove with a
second sealing means 21 held therein. Also this sealing means is an
annular sealing in the form of an O-ring. The second sealing means
21 has a smaller opening diameter than the first sealing means 15.
Between the two sealing means 15,21, there is thus generated an
annular partial region 22 which is exposed to the existing pressure
difference since its outer side is subjected to the atmospheric
pressure and its inner side is subjected to the vacuum. Because of
the provision of opening 17, a balanced pressure prevails in the
region enclosed by the second sealing means 21, i.e. the vacuum in
the interior of the casing will in this region act on the vacuum
cover 20. Thus, vacuum cover 20 is pressed in the direction toward
wall 13 under the effect, of the atmospheric pressure.
[0014] On its front-side end, casing 10 is closed by a protective
cover 23 which has no sealing function. Protective cover 23
includes a hollow space 24 for accommodating the vacuum cover 20,
and a positioning means 25, formed as a stepped shoulder, for
positioning the vacuum cover 20. The protective cover serves for
protection of the vacuum cover as well as the circuit board and the
elements connected thereto.
[0015] From the inner side 18 of circuit board 16, electric lines
26 extend into the interior of the casing. These lines can be power
supply lines or also control or signal lines. The lines are
connected to the conductor lines of the circuit board by soldering
or plug attachment.
[0016] External electric conductors 27 are soldered or plugged to
the outer side 19 of circuit board 16. Said conductors 27 are
guided through the interior space 24 to a plug device 28 configured
as an electrical multiple plug. Plug device 28 serves for
connection of an external cable. The device is located on a side
wall of protective cover 23 but could also be located on the rear
surface.
[0017] Circuit board 16 does not laterally project beyond side wall
13. The partial region 22 between the sealing means 15 and 21 is
provided as a connection region for the electric conductors 27.
[0018] The embodiment according to FIG. 2 is different from the
embodiment according to FIG. 1 only in that the circuit board 16 is
additionally provided with electrical components 30, such as e.g.
resistors, capacitors, processors or memory devices. The components
30 can be passive and active components alike.
[0019] As in the first embodiment, vacuum cover 20 includes a
recess which is enclosed by the edge supporting the sealing means
21. In FIG. 2, said recess 31 serves for accommodation of the
components 30 fastened to the outer side 19 of the circuit
board.
* * * * *