VACUUM PUMP

POMPE A VIDE

English Abstract

The invention relates to a vacuum pump (10) having a vacuum-tight housing (12) and having a gas-tight electrical leadthrough (20) for producing an electrical connection between an electrical component (14, 16, 18) within the housing (12) and the housing outer side. The leadthrough (20) is formed by a housing opening (22), by a sealing compound body (24) which is seated on the opening, by an electrical line in the sealing compound body (24), by a sealing ring (26) between the opening edge of the housing opening (22) and the sealing compound body (24), and by a fixing (32) for fastening the sealing compound body (24) to the housing (12).

French Abstract

L'invention se rapporte à une pompe (10) à vide comprenant un boîtier (12) étanche au vide et une traversée (20) électrique étanche au gaz pour établir une liaison électrique entre un composant (14, 16, 18) électrique à l'intérieur du boîtier (12) et le côté extérieur du boîtier. La traversée (20) est formée par une ouverture (22) de boîtier, un corps (24) de masse de scellement reposant sur l'ouverture, une ligne électrique dans le corps (24) de masse de scellement, une bague (26) d'étanchéité entre le bord d'ouverture de l'ouverture (22) de boîtier et le corps (24) de masse de scellement et un dispositif (32) de fixation pour fixer le corps (24) de masse de scellement au boîtier (12).

Claims

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Claims
1. A vacuum pump (10) comprising
a vacuum-tight housing (12),
an elastic component (14,16,18) arranged within said housing (12),
a gas-tight electrical leadthrough assembly (20) for producing an
electrical connection between an electrical component (14,16,18)
within the housing (12) and the exterior of the housing,
wherein said leadthrough assembly (20) is formed by
a housing opening (22),
a sealing compound body (24) positioned on said housing opening
(22) and enclosing an electric line (34) extending between the inte-
rior of the housing and the exterior of the housing,
a sealing ring (26) between an opening edge (28) of the housing
opening (22) and the sealing compound body (24), and
a fixing means (32) for attachment of the sealing compound body
(24) to the housing (12).
2. The vacuum pump (10) according to claim 1, characterized in that said
sealing compound body (24) is mounted to said housing opening (22)
from the outside.

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3. The vacuum pump (10) according to claim 1 or 2, characterized in that
said fixing means (32) is a sealing-compound housing (30).
4. The vacuum pump (10) according to any one of claims 1 - 3, charac-
terized in that said electric line (34) comprises a circuit board (44) ar-
ranged within the sealing compound body (24).
5. The vacuum pump (10) according to any one of claims 1 - 4, charac-
terized in that said electric line (34) comprises respectively one electric
plug (40,42) towards the interior and towards the exterior.
6. The vacuum pump (10) according to claim 4 or 5, characterized in that
said circuit board (44) comprises electronic components (46,47,48).
7. The vacuum pump (10) according to claim 6, characterized in that one
of said electronic components (46) is configured as a readable pump-
data memory.
8. The vacuum pump (10) according to any one of claims 1 - 7, charac-
terized in that the material of the sealing compound body (24) is an
epoxy resin.

Description

CA 02658744 2009-01-22
Oerlikon Leybold
Sg/Dt
Vacuum pump
The invention relates to a vacuum pump wherein the pump housing is pro-
vided with a gas-tight electrical leadthrough assembly.
Vacuum pumps normally comprise electrical components arranged within a
vacuum-tight housing, such as e.g. an electric drive motor, electric sensors,
a magnetic bearing etc. The electrical components on the vacuum side have
to be connected to the outer side of the housing through electric lines. For
this purpose, electric lines have to be led from the interior of the housing
to
the exterior of the housing via a gas-tight electrical leadthrough assembly.
Known from the state of the art are leadthrough assemblies consisting of a
contact plate provided with contact pins passing therethrough, said contact
plate being configured to close a corresponding opening of the housing.
With the aid of a sealing ring, the contact plate is sealed towards the edge
of said housing opening. The sealing of said contact pins in the contact plate
can be effected only with difficulties and will not be reliable in case that
me-
chanical stresses happen to act on the contact plate.
In view of the above, it is an object of the invention to provide a vacuum
pump whose housing is provided with a reliable gas-tight electrical lead-
through assembly.
The above object is achieved by a vacuum pump having the features de-
fined in claim 1.
The vacuum pump according to the invention comprises a vacuum-tight
housing and an electrical component arranged within the housing. The gas-

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tight electrical leadthrough assembly for producing an electrical connection
between said electrical component and the exterior of the housing is formed
by an opening in the housing; a sealing compound body seated on the
opening of the housing, with an electric line, extending between the inner
side of the housing and the outer side of the housing, passing through said
sealing compound body; a sealing ring arranged between the opening edge
of the opening of the housing and the sealing compound body; and a fixing
means for fastening the sealing compound body to the housing. Thus, the
leadthrough assembly substantially consists of three parts, namely the seal-
ing compound body having all of the electric lines cast into it, the sealing
ring for safeguarding a gas-tight and vacuum-tight sealing action between
the sealing compound body and the edge of the opening, and a sealing-
compound body fixing means which is effective to permanently press the
sealing compound body onto the opening edge of the opening of the hous-
ing.
The sealing compound has a certain elasticity, safeguarding the gas-tight
and vacuum-tight passage of the electric line or lines through the sealing
compound body. Preferably, both proximally and distally, the electric line or
lines should at least slightly project outwards from of the sealing compound
body so as to allow for the attachment of electric connection lines. The seal-
ing effect between the sealing compound body and the edge of the opening
is reliably obtained by a sealing ring.
The thickness of the sealing compound body should be at least 5 mm and
preferably 10 mm so as to guarantee a sufficiently long sealing space be-
tween the electric line and the sealing compound.
By casting all of the electric lines into a monolithic, elastic sealing com-
pound body, it is made possible to realize a reliable, vacuum-tight passage
in a relatively simple manner also in case of a large number of electric
lines.
This is of relevance particularly for vacuum pumps with magnetic bearings

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since these pumps will often require a number of 50 or more electric con-
duits to be led through the vacuum-tight housing.
According to a preferred embodiment, the sealing compound body is seated
from the outside onto the opening edge of the opening of the housing. Dur-
ing operation, under the effect of the differential pressure between the at-
mospheric air pressure acting from the outside and the vacuum prevailing in
the housing, the sealing compound body will be pressed onto the edge of
the opening of the housing. In this manner, the sealing effect between the
sealing compound body and the edge of the opening of the housing will be
additionally intensified when the vacuum pump is operated.
Preferably, the fixing means is a sealing-compound housing configured to
almost fully take up the sealing compound and to press the sealing com-
pound against the edge of the opening of the housing. The sealing-
compound housing comprises only one proximal opening and one distal
opening for the electric line or lines. The primary function of the sealing-
compound housing resides in fixing the sealing compound body in place
while, on the other hand, this housing does not primarily have a sealing
function. Nonetheless, the sealing-compound housing may in fact have a
sealing effect as well.
According to a preferred embodiment, the electric line can comprise a con-
ductive board arranged in the sealing compound. Thus, the electric line is
partially realized in the form of a conductor trace on a printed circuit
board.
The electric line can further comprise respectively one plug projecting from
the sealing compound body towards the interior of the housing, and one
plug projecting from the sealing compound body towards the exterior of the
housing. Said two electric plugs can be connected to each other by the
printed circuit board but can also be electrically connected to each other in
another manner.

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According to a preferred embodiment, the printed circuit board comprises
electronic components. Possible electronic components in this regard are all
electronic components which may serve for amplification, interference sup-
pression or another manipulation of electric signals, i.e. components such
as, for instance, amplifiers, suppressor chokes and capacitors, integrated
circuits for signal processing, etc.
Preferably, the electronic component is a readable pump-data memory
adapted for storage therein of pump-specific functional parameters, e.g. an
error history of the respective vacuum pump, and for retrieval therefrom of
such functional parameters at any time.
Preferably, the sealing compound material is an epoxy resin. Epoxy resins
are vacuum-tight and elastic and are castable at relatively low temperatures
which are not destructive to electronic components.
An embodiment of the invention will be explained in greater detail here-
under with reference to the drawing.
The Figure schematically shows a vacuum pump and, in partly sectional
view, the vacuum pump housing provided with a gas-tight electrical lead-
through assembly.
Schematically shown in the Figure is a vacuum pump 10 which can be con-
figured as a displacement pump but preferably will be configured as a high-
vacuum turbomolecular pump with magnetic bearing.
Vacuum pump 10 comprises a vacuum-tight metal housing 12 having a
housing wall 13 and accommodating a plurality of electrical components
14,16,18, notably an electric drive motor 14, a magnetic bearing 16 as well
as pump sensors 18. Drive motor 14 is operative to drive a pump rotor of
the turbomolecular pump via a shaft 17.

CA 02658744 2009-01-22
Vacuum pump 10 is provided with a gas-tight electrical leadthrough assem-
bly 20 for establishing an electrical connection between said electrical com-
ponents 14,16,18 and the exterior of said housing. Leadthrough assembly
20 is substantially formed by a housing opening 22 in housing wall 13; a
sealing compound body 24 seated on said housing opening 22 on the out-
side of the latter; an elastic sealing ring 26 between an opening edge 28 of
housing opening 22 and the sealing compound body; a fixing means 32
formed as a sealing-compound housing 30; and an electric line 34. Said
sealing ring 26 is seated in an annular groove 27 of sealing compound body
24.
Electric line 34 is formed by a proximal electric plug 40, a distal electric
plug
42, and a printed circuit board 44 comprising conductive traces and electri-
cal components 46,47,48. Said electrical components 46 - 48 are an inte-
grated circuit 46 and passive components 47,48. Said plugs 40,42 comprise
more than 50 plug pins, each one of them individually connected to conduc-
tive traces on circuit board 44.
Stored in integrated circuit 46 are functional parameters and data of vac-
uum pump 10. The functional parameters are pump-specific and include an
error history of vacuum pump 10 which, using a suitable reading device 50,
can be read out via distal plug 42 through an electrical data line 52 adapted
to be plugged onto plug 42.
All parts of electric line 34 are enclosed in a gas-tight manner within the
sealing compound body 24 cast therearound. The sealing compound mate-
rial is an epoxy resin. The epoxy resin can be provided with fine-granulated
admixtures which have a positive influence on thermal expansion, thermal
conductivity and/or other physical parameters.
Under the effect of the cup-shaped sealing-compound housing 30 forming a
fixing means 32 and being fixed, e.g. screwed, to the outside of housing 30,
the sealing compound body 24 is pressed onto said opening edge 28, result-

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ing in a gas-tight and vacuum-tight sealing condition between opening edge
28 and sealing compound body 24.

Representative Drawing