WO2009012898A1

WO2009012898A1 - Vacuum housing and method for producing an insert for a vacuum housing

Info

Publication number: WO2009012898A1
Application number: PCT/EP2008/005665
Authority: WO
Inventors: Hans-Jürgen Schlüter; Dirk Wohlers; Horst Sudholz
Original assignee: Thermo Fisher Scientific (Bremen) Gmbh
Priority date: 2007-07-20
Filing date: 2008-07-11
Publication date: 2009-01-29
Also published as: DE112008001722A5; DE102007034478A1

Abstract

The invention relates to a vacuum housing, with an insert in a housing wall, in particular as a bushing of an electrical connection, with at least one body held in the insert, which body extends through the housing wall, wherein the insert has an insert part made from a polymer material and a sealing part made from an elastomer material, and wherein the sealing part (12) seals off the body with respect to the insert part.

Description

Vacuum housing and method of making an insert for a vacuum housing

description

The invention relates to a vacuum housing, with an insert in a housing wall, in particular as performing an electrical connection, as a mechanical feedthrough, for sight glasses or for other vacuum-tight interruptions of the housing wall. Moreover, the invention relates to a method for producing an insert for a vacuum housing.

Technical-scientific apparatus or instruments may be equipped with a vacuum system. Due to the vacuum system, areas of higher pressure (also normal pressure) are separated from areas of relatively low pressure (also 10 ^'9 mbar). For this purpose, a housing with correspondingly stable walls is provided as part of the vacuum system.

Low-pressure side and high-pressure side of the vacuum system must be interconnected or coupled for a variety of purposes and applications. For example, electrical lines are led into the housing or lines for liquids and gases (also capillaries). For certain applications, sight glasses should be provided in the housing wall. In all cases, the housing wall has an interruption with a vacuum-tight arranged use.

A particularly important field of application of the invention are vacuum systems for mass spectrometers. Preferably, it is about electrical feedthroughs in walls of corresponding vacuum housing. Other applications related to vacuum systems are also within the scope of the invention.

Known electrical feedthroughs comprise a conductive pin or wire, which is usually surrounded by a ceramic insulator which is embedded in a metal part. The metal part is inserted in the housing wall vacuum-tight. The permanent connection of ceramic and metal parts is complicated and expensive. In DE 10 99 609 a vacuum-tight electrical feedthrough is shown, in which an electrical conductor seals against an insulating body by means of an annular sealing means with an adjacent screw connection. The insulating body is held in a socket which clamps the insulating body together with a sealing ring and which may be welded to a housing wall. The assembly, in particular in the region of the transition between the electrical conductor and the insulating body is relatively expensive because of the necessary screwing.

Object of the present invention is to provide a cost-effective and efficient in assembly solution for implementation on a vacuum housing. In particular, expensive ceramic sealing and insulating material should be avoided, as well as a metal part as a carrier.

The vacuum housing according to the invention has the features of claim 1. Thereafter, the use of multiple parts, with an insert of a polymer material and a sealing member made of an elastomeric material, wherein the sealing member seals the body held in use to the insert and the insert is molded or molded onto the body. The body is, for example, a conductive pin or wire, such as steel, via which an electrical connection between the interior of the vacuum housing and the outside of the same can be produced. Polymer and elastomer are to be selected as vacuum-suitable materials. In conjunction with electrical conductors, the materials should also be electrically insulated, in particular the polymer material. The insert made of the polymer material is suitably connected to the housing wall, such as by screwing or gluing and in conjunction with a sealing ring or other seal. The sealing member ensures a vacuum-tight connection between the body and polymer material, even with occurring mechanical stresses, such as thermal expansion, production-related shrinkage processes, acting on the body mechanical forces by connecting and disconnecting lines.

The insert may also contain a plurality of bodies, for example conductive wires or rods. Preferably, each body is then assigned its own sealing part, so that a plurality of sealing parts are arranged in the insert part. According to another aspect of the invention, the polymer material is injection-moldable. Accordingly, the insert is made by injection molding. Preferably, it is a polycarbonate material. The insert can be made entirely of polycarbonate by injection molding. Polycarbonate has the required tightness (low diffusion) and low outgassing after injection molding.

According to another aspect of the invention, the elastomeric material includes silicone or a silicone compound. Preferably, the sealing member is made of silicone and seals the insert against the body, even with shrinkage after injection molding, at mechanical stresses. Silicone adheres very well to many solids, especially steel. By heat and pressure during injection molding also creates an intimate connection between the silicone of the seal member and the material of the insert.

According to a further aspect of the invention, the body held in use is an electrical conductor, in particular a metallic electrical conductor. Preferably, it is one or more pins, which are guided by means of the insert through the housing wall.

According to a further aspect of the invention, the insert part is made in several parts with a preform directly on the sealing part and with a molded on the pre-molded part area. The injection-molded area preferably completely surrounds the pre-molded part, at least in the direction of the plane of the housing wall. Perpendicular to the housing wall, the pre-molded part can protrude over the molded area.

In a further development of the invention it is provided that the pre-molded part is designed in several parts with container and lid, wherein the sealing part is provided in the container. In this case, the container can be made in a first pre-injection and parallel in time or later the lid.

According to a further aspect of the invention, the pre-molded part surrounds the sealing part completely, at least in the direction or in the plane of the housing wall. If the Preimpact surrounds the sealing part completely, the body, conductor or the like extends through both parts - pre-molded part and sealing part - through.

According to the invention it is further provided that the insert part has a groove for receiving a ring seal, wherein the ring seal seals the insert to the housing wall. Advantageously, the insert outside the groove with the housing wall is firmly connected, in particular screwed.

The invention also provides a greatly simplified embodiment of a vacuum housing with a vacuum-tight interruption of a housing wall. The housing wall or even the housing as a whole can be made of a polymer material, in particular polycarbonate. An additional use of polymer material is then not mandatory. Instead, a sealing member made of an elastomeric material in the housing wall is arranged, thus sealing a guided through the wall body towards the wall from. The elastomeric material extends on or within the housing wall around the body. Preferably, the elastomeric material is silicone or other suitable elastomer.

The method according to the invention for producing an insert for vacuum housings has the following steps:

a) a preform is sprayed around a body to be embedded, such that the body protrudes from both sides of the preform, and such that a cavity around the body remains free for a sealing part.

b) the sealing part is introduced into the cavity,

c) then the preform is overmolded to obtain a desired shape of the insert to form a molded outer part of the insert.

The production takes place by injection molding. The division of the method in the production of the pre-molded part, the introduction of the sealing part and the subsequent Injection of an outer part has been found to be advantageous for the tightness and dimensional accuracy of the insert.

According to a further aspect of the invention, the preform is made in several parts, namely at least with container and lid. Accordingly, first the container is pre-injected around the body, then the sealing part is introduced into the container and then the lid is pre-injected to cover the sealing part. Lid and container are the components of the preform.

Another method according to the invention for producing an insert for a vacuum housing has at least the following steps:

a) a body protruding from the insert on both sides after production is provided with a sealing part,

b) an insert is molded around the seal member by injection molding.

As previously mentioned, the sealing member is made of an elastomer, preferably of silicone or other suitable elastomer, such as rubber or acrylic. The insert consists of an injection-moldable polymer, in particular polycarbonate.

In the device according to the invention or in accordance with the method according to the invention, the electrical conductor or, more generally, a body to be passed through the housing wall is embedded permanently and in particular in a binding manner, preferably in a preferably inelastic plastic body after curing. This is preferably done by casting or injection molding of the insert made of plastic. To avoid the formation of subsequently resulting leakage channels or cracks due to thermal and mechanical stress, an elastomer compound is integrated into the device. The elastomer mass - the sealing part - is permanently connected in the manufacturing process with the body and with the plastic of the surrounding insert part. A material which adheres well to metallic conductors as well as to sight glasses and plastics is silicone. The resulting connection is reliable and requires no further manual labor during production. Because of the adhesion of the sealing part to be performed on the body and on the Surrounding insert is per se no sealing force required. The material of the sealing part is initially plastic flowing and permanently elastic after setting.

Alternatively or in addition to the adhesive material pairings - the sealing part adheres to the insert part and the sealing part adheres to the body - the sealing part can be predominantly or completely enclosed by the insert part as far as the body. That is, the sealing member is outside the insert hardly or not accessible.

The manufacturing method can be carried out such that the body, for example an electrical conductor, is surrounded by an adhesive sealant as a sealing part.

In this case, the body already has a cast and especially cured

Preimpatch have. But this is not necessary. In the next manufacturing step, the body and the sealing member are embedded together in the insert part or in a part thereof. The embedding is preferably carried out by casting or injection molding of the insert part, possibly in conjunction with a subsequent curing or setting of the latter.

The proposed embedding of the sealing member prevents the possibility of the formation of leakage channels or cracks over time. Due to thermal or mechanical stress forces are absorbed in the region of the sealing part and there is a reliable crack-free zone, which leads to the tightness of the entire component. In this case, a sealing effect of the sealing part is advantageous but not mandatory. Also, an acting on the sealing part, additional contact force is not required. During casting of the insert, the initially plastic material flows around the body with the adjacent sealing part, then binds or hardens, and is then inelastic. In injection molding of the insert, a relatively high contact pressure acts on the cast-in sealing part, which offers additional advantages in terms of the required long-term sealing, in particular in conjunction with said adhesive material pairings.

The insert made by the method may be conventionally connected to the vacuum housing, for example by screwing it to the vacuum housing wall with the seal ring therebetween. For this purpose, the vacuum housing, for example, only has blind bores with an internal thread for the screw connection and a sufficiently large opening for use. The insert itself can be prefabricated by the manufacturer and checked for the tightness of the transition between insert and body. The end user can replace inserts himself, without having to check the tightness of the connection from the insert to the body. Instead of a sealing ring between the insert and the vacuum housing, the insert may also have an integrated seal, preferably of the same material as the embedded sealing part. The provided for the connection of the insert to the vacuum housing seal may, for. B. may be cast on the insert, such as a molded silicone gasket. This reduces the number of parts and ensures that no sealing ring is lost.

In the simplified embodiment, the housing wall of the vacuum housing is produced by casting, by injection molding, hot forming or high pressure forming and in this way the body is embedded with the molded sealing part in the housing wall. Again, preferably the sealing member is first molded or molded onto the body and then cast or embedded the resulting unit in the housing wall of a polymer material, or the housing wall is connected to the unit of body and preferably tied, elastic Seal part molded. Again, adhesive material pairings are preferred. With sufficient embedding of the sealing part in the housing wall but the adhesive material pairings are not mandatory. It is more important that the material of the housing wall is also integrally formed or cast on the body and hardens or sets.

The invention also provides a mass spectrometer with a vacuum housing in the described embodiment.

Further features of the invention will become apparent from the description, moreover, and from the claims. Advantageous embodiments of the invention are explained below with reference to figures. Show it:

1 shows a cross section through an insert for a vacuum housing,

2 shows a cross section through an insert with sight glass,

3 shows a cross section through an insert with a light guide or a capillary,

4 shows a cross section through a housing wall with performed conductor. In Fig. 1 can be seen an insert 10 for a vacuum housing, wherein the insert 10 has the function of a passage through a housing wall (not shown). An electrical conductor 11, which is designed here as a steel pin, is passed through.

The insert 10 also has a sealing part 12 and an outer part 13 and pre-molded part 14 existing insert part. The preform 14 is divided into a container 15 and a lid 16, wherein a dividing line 17 between these two parts is perpendicular to the conductor 1 1 and preferably located approximately halfway up the sealing part 12.

In the production of the insert 10, the procedure is preferably such that initially the container 15 is formed as a partial pre-molded part with the conductor 11 cast round on both sides but protruding on both sides. Subsequently, in a free cavity 18 of the container 15, a sealing compound consisting of an elastomer is introduced as the sealing part 12. In this case, the sealant or the sealing member 12 project beyond the cavity 18 and have approximately a spherical shape. At the same time the sealant is sealingly on the conductor 11 and of course on the container 15. Subsequently, the cover 16 is formed as a second partial pre-molded part for covering the sealing part 12. As a result, the sealing member 12 is arranged sunk, namely completely enclosed. It can be formed in the region of the dividing line 17, a tight connection between the container 15 and cover 16.

Finally, the outer part 13 is molded radially on the outside of container 15 and lid 16. The latter has an annular groove 19 for a voltage applied to the housing wall ring seal (not shown). In addition, 19 connection bores 20 are provided outside of the annular groove.

The electrical conductor 11 is shown here with a smooth, rod-shaped shape. Alternatively, the conductor 11 may have on its outside elevations and depressions for tighter connection with the pre-molded part 14th

The multi-step production with pre-molded part 14 and outer part 13 ensures a particularly intimate and tight connection of the individual components. Heat and pressure during injection molding of the outer part 13 ensure a good connection At the same time, the preform 14 is compressed by the high pressure with the filled sealant or the sealing member 12 and so further improves the tightness. The formation of cracks in this region is effectively prevented, so that no leak path can form.

Basically, the shape of the insert 10 depends on the application. As an alternative to the form shown, the insert may have the geometry of standardized vacuum flanges and connectors, for example in accordance with the standards for small flanges (KF) or according to the CF standard, in particular for components with an ultra-high vacuum. Instead of the annular groove with inserted sealing ring and other sealing means may be provided.

Also, special application-specific forms of the insert 10 are possible, even with clamps or screws fixed shapes. Also possible is an assembly with directly cast on the thread in a corresponding counterpart or a clip assembly with clips inside or outside the vacuum housing. The clips or tabs can also be part of the insert directly.

The vacuum housing or a wall thereof may be made in one piece with the insert. Also, a plurality of conductors 11 or body may be included in a common use, preferably with its own sealing member per body.

Instead of an electrical conductor other bodies may be provided, such as sight glasses (viewports), optical or opto-electronic couplings, glass fibers, mechanical feedthroughs (for example, rotary joints), capillaries, etc. The

Invention is basically usable for all types of feedthroughs, ie for

Performing non-plastics in general by urformed plastic parts for

Mass, energy or information transport in connection with a vacuum housing. The plastic parts can also be formed in other ways than by injection molding, for example by extrusion.

Fig. 2 shows an insert with sight glass 21 in the insert part 22. Completely embedded between sight glass 21 and insert 22 is the circumferential sealing part 12. At his Bottom, the insert 10 has a circumferential sealing edge 23. The insert is located with the sealing edge 23 on a housing wall, not shown. The sealing edge 23 acts sealingly either by sinking into a softer housing element or by deformation of the relatively narrow sealing edge in contact with a harder housing element. Preferably, the insert 10 shown in FIG. 2 is rotationally symmetrical with a correspondingly cylindrical sight glass 21.

Fig. 3 shows an insert 10 as a passage for a light guide or capillary 24. Analogous to FIG. 1 here is a preform 14 is provided, in which the fully embedded seal member 12 is held and seals against the capillary 24. Outside of the pre-molded parts 14, an outer part 13 is molded. Pre-molded part 14 and outer part 13 form here the insert part. On the underside of the outer part 13, an elastic sealing material 25 is peripherally worked directly. It may be the same material as in the seal member 12. But also possible is another elastic material.

Finally, Fig. 4 relates to a simplified embodiment. A housing wall 26 made of a polymer material accommodates directly the sealing part 12 and the electrical conductor 11 passed through. The housing wall 26 may be manufactured together with the guided conductor 11 in one operation. Preferably, then only the seal member 11 is molded. For this purpose, the housing wall 26 on the outside in the region of the conductor 11 on a recess 27 in which the seal member 12 is receiving. The latter may protrude beyond the housing wall or be provided only within the trough 27.

The invention is preferably usable in the context of mass spectrometers and with high vacuum or ultrahigh vacuum conditions in a vacuum housing. LIST OF REFERENCE NUMBERS

10 use

11 electrical conductors

12 sealing part

13 outdoor unit

14 pre-molded part

15 containers

16 lids

17 dividing line

18 cavity

19 ring groove

20 screw connection

21 sight glass

22 Insert 3 Sealing edge 4 Capillary 5 Elastic sealing material 6 Housing wall 7 Trough

Claims

claims

1. Vacuum housing with an insert (10) in a housing wall, in particular as performing an electrical connection, for a mechanical implementation, for sight glasses or other vacuum-tight interruptions of the housing wall, with at least one in use (10) held Body extending through the housing wall, the insert (10) having an insert made of a polymer material and a seal member (12) made of an elastomeric material, the seal member (12) sealing the body to the insert member, and wherein the insert is molded or molded onto the body.

2. Vacuum housing according to claim 1, characterized in that the polymer material is injection-moldable.

3. Vacuum housing according to claim 1 or 2, characterized in that the polymer material is a polycarbonate material.

4. Vacuum housing according to claim 1 or one of the further claims, characterized in that the elastomer material includes or is silicone or a silicone compound.

5. Vacuum housing according to claim 1 or one of the further claims, characterized in that the in use (10) held body is an electrical conductor (11), in particular a metallic electrical conductor.

6. Vacuum housing according to claim 1 or one of the further claims, characterized in that the insert part is multi-part, with a pre-molded part (14) directly on the sealing part (12) and with a pre-molded part (14) molded area, in particular an outer part ( 13).

7. Vacuum housing according to claim 6, characterized in that the pre-molded part (14) is designed in several parts with container (15) and cover (16), wherein in the container, the sealing part (12) is provided.

8. Vacuum housing according to claim 6 or 7, characterized in that the pre-molded part (14) completely surrounds the sealing part (12), at least in the direction of the housing wall.

9. Vacuum housing according to claim 1 or one of the further claims, characterized in that the insert part has a groove (19) for receiving a ring seal, wherein the ring seal seals the insert (10) to the housing wall.

10. Vacuum housing with a vacuum-tight interruption of a housing wall (26), in particular as an electrical connection, as a mechanical implementation, for sight glasses or other interruptions of the housing wall, with at least one body which extends through the housing wall (26), wherein the housing wall (26) consists of a polymer material, wherein a sealing part (12) of an elastomeric material between the body and the housing wall is arranged and seals the body to the housing wall.

11. A method for producing an insert (10) for vacuum housing, in particular according to one of the preceding claims, with the following steps,

a) a preform (14) is injected around a body to be embedded such that the body protrudes on both sides of the preform (14), and such that a cavity (18) around the body for a sealing part (12) free b) the sealing part (12) is introduced into the cavity (18), c) then the pre-molded part (14) is overmolded to obtain a desired shape of the insert (10) to form a molded part

External part of the insert.

12. The method according to claim 11, characterized in that the pre-molded part (14) is designed in several parts, namely at least with container (15) and cover (16), and in that first the container is pre-injected around the body, then the sealing part (12) is introduced into the container (15), and then the cover (16) is pre-injected to cover the sealing part (12).

13. A method for producing an insert (10) for a vacuum housing, in particular according to one of the preceding claims 1 to 9, with the following steps:

a) a body projecting from the insert (10) on both sides after production is provided with a sealing part (12), b) an insert part is molded around the sealing part (12) by injection molding.

14. Mass spectrometer with a vacuum housing according to one of the preceding claims 1 to 10.