VACUUM PUMP

Abstract

A vacuum pump (10) has a vacuum-tight housing (12) and having 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. The leadthrough assembly (20) is formed by a housing opening (22), by a sealing compound body (24) seated on the opening, by an electric 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 means (32) for fastening the sealing compound body (24) to the housing (12).

Description

BACKGROUND

The invention relates to a vacuum pump wherein the pump housing is provided 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 mechanical 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.

SUMMARY

The vacuum pump according to the invention comprises a vacuum-tight housing and an electrical component arranged within the housing. The gas-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 sealing 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 housing.

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 sealing 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 between the electric line and the sealing compound.

By casting all of the electric lines into a monolithic, elastic sealing compound 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 since these pumps will often require a number of 50 or more electric conduits 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. During operation, under the effect of the differential pressure between the atmospheric 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 compound 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 conductive 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.

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 suppression 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.

The following is a detailed description of an embodiment of the invention with reference to the drawing.

BRIEF DESCRIPTION OF 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.

DETAILED DESCRIPTION

Schematically shown in the FIGURE is a vacuum pump 10 which can be configured 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.

Vacuum pump 10 is provided with a gas-tight electrical leadthrough assembly 20 for establishing an electrical connection between said electrical components 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 outside 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 electrical components 46,47,48. Said electrical components 46-48 are an integrated circuit 46 and passive components 47,48. Said plugs 40,42 comprise more than 50 plug pins, each one of them individually connected to conductive traces on circuit board 44.

Stored in integrated circuit 46 are functional parameters and data of vacuum 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 material 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, resulting in a gas-tight and vacuum-tight sealing condition between opening edge 28 and sealing compound body 24.

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 construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A vacuum pump comprising

a vacuum-tight housing,

an elastic component arranged within said housing,

a gas-tight electrical leadthrough assembly for producing an electrical connection between an electrical component within the housing and the exterior of the housing,

wherein said leadthrough assembly is formed by

a housing opening,

a sealing compound body positioned on said housing opening and enclosing an electric line extending between the interior of the housing and the exterior of the housing,

a sealing ring between an opening edge of the housing opening and the sealing compound body, and

a fixing means for attachment of the sealing compound body to the housing.

2. The vacuum pump according to claim 1, wherein said sealing compound body is mounted to said housing opening from the outside.

3. The vacuum pump according to claim 1, wherein said fixing means is a sealing-compound housing.

4. The vacuum pump according to claim 1, wherein said electric line comprises a circuit board arranged within the sealing compound body.

5. The vacuum pump according to claim 1, wherein said electric line comprises respectively one electric plug towards the interior and towards the exterior.

6. The vacuum pump according to claim 4, wherein said circuit board comprises electronic components.

7. The vacuum pump according to claim 6, wherein one of said electronic components is configured as a readable pump-data memory.

8. The vacuum pump according to claim 1, wherein the material of the sealing compound body is an epoxy resin.