ELECTRICAL FEEDTHROUGH ASSEMBLY WITH INSULATION ELEMENT

Abstract

An electrical feedthrough assembly is disclosed having a base body with at least one opening for a conductor embedded in a fixation material that is fed into each of the respective openings and sealing the respective opening. The electrical feedthrough assembly further includes an insulation element made from a material having a first glass-transition temperature t.sub.g1, wherein the insulation element is affixed by an adhesive material arranged between the insulation element and the fixation material.

Claims

1. An electrical feedthrough assembly, comprising a base body with at least one opening for a conductor embedded in a fixation material that is fed into each of the respective openings and sealing the respective opening, wherein said electrical feedthrough assembly further comprises an insulation element made from an ethylene propylene diene monomer (EPDM) rubber, or a hydrogenated nitrile-butadiene rubber (HNBR), or a nitrile-butadiene rubber (NBR), or a fluoroelastomer material (FKM), wherein the insulation element is affixed by an adhesive material arranged between the insulation element and the fixation material and optionally between the insulation element and the base body, wherein the adhesive material is electrically insulating, wherein within an operating temperature range of from 45 C. to 120 C., an absolute value of a difference between a first coefficient of thermal expansion 1 of the adhesive material and a second coefficient of thermal expansion 2 of the fixation material is in the range of from 10.Math.10.sup.6 K.sup.1 to 180.Math.10.sup.6 K.sup.1, and wherein when i) the adhesive material is laterally enclosed by a sidewall, the lateral expansion of the adhesive material is restricted, and the adhesive material has a thickness of between 0.3 mm and 1.0 mm, and when ii) the adhesive material is not laterally enclosed by a sidewall, the lateral expansion of the adhesive material is possible, and the adhesive material has a thickness of between 0.1 mm and 0.6 mm.

2. The electrical feedthrough assembly according to claim 1, wherein a pocket for the adhesive material having a side wall is defined by the base body and the fixation material, wherein the side wall is a slanted side wall.

3. The electrical feedthrough assembly according to claim 1, wherein a first glass transition temperature t.sub.g1 of the insulation element is at most 0 C. and/or wherein a second glass transition temperature t.sub.g2 of the adhesive material is higher than 50 C. and/or wherein a difference between a second glass-transition temperature t.sub.g2 and a first glass-transition temperature t.sub.g1 is at least 30 K.

4. The electrical feedthrough assembly according to claim 1, wherein within the operating temperature range from 45 C. to 120 C., the first coefficient of thermal expansion 1 of the adhesive material is in the range of from 20.Math.10.sup.6 K.sup.1 to 140.Math.10.sup.6 K.sup.1 for temperatures below the glass transition temperature of the adhesive material, and 1 is in the range of from 120.Math.10.sup.6 K.sup.1 to 200.Math.10.sup.6 K.sup.1 for temperatures from the glass transition temperature and/or wherein the second coefficient of thermal expansion 2 of the fixation material is in the range of from 4.Math.10.sup.6 K.sup.1 to 12.Math.10.sup.6 K.sup.1.

5. The electrical feedthrough assembly according to claim 1, wherein the adhesive material has a Shore D hardness of from 40 to 95.

6. The electrical feedthrough assembly according to claim 1, wherein the adhesive material has a modulus of elasticity of at least 2000 MPa.

7. The electrical feedthrough assembly according to claim 1, wherein the material of the base body is steel.

8. The electrical feedthrough assembly according to claim 1, wherein the fixation material is a glass.

9. The electrical feedthrough assembly according to claim 1, wherein the adhesive material is an acrylate adhesive, a polyurethane adhesive, a silicone adhesive, or an epoxy adhesive.

10. The electrical feedthrough assembly according to claim 1, wherein the adhesive material and/or the material of the insulation element have a specific electrical resistance of at least 1.Math.10.sup.10 cm.

11. The electrical feedthrough assembly according to claim 1, wherein the adhesive material and the material of the insulting element comprises an inorganic filler material.

12. The electrical feedthrough assembly according to claim 11, wherein the total amount of filler material in the adhesive material and the material of the insulting element is at least 30% by weight.

13. The electrical feedthrough assembly according to claim 1, wherein a surface energy of the material of the insulation element is at least 22 J/m.

14. The electrical feedthrough assembly according to claim 1, wherein a difference between a third coefficient of thermal expansion 3 of the base body and the second coefficient of thermal expansion 2 of the fixation material is less than 2 ppm/K.

15. The electrical feedthrough assembly according to claim 1, wherein the base body, the conductor and the fixation material form a compression seal, and wherein a difference between a third coefficient of thermal expansion 3 of the base body and the second coefficient of thermal expansion 2 of the fixation material is at least 2 ppm/K.

16. The electrical feedthrough assembly according to claim 1, wherein the insulation element has a cylindrical section surrounding the conductor, wherein grooves and/or annular rings are arranged on the cylindrical section, and/or wherein the insulation element has an extension section surrounding the conductor in a distance such that a gap is formed, wherein grooves and/or annular rings are arranged on the wall of the extension section facing towards the conductor.

17. An electric compressor comprising an electrical feedthrough assembly according to claim 1.

18. The electrical feedthrough assembly according to claim 3, wherein a first glass transition temperature t.sub.g1 of the insulation element is at most at most 10 C.; and/or wherein a second glass transition temperature t.sub.g2 of the adhesive material is higher than 70 C.; and/or wherein a difference between a second glass-transition temperature t.sub.g2 and a first glass-transition temperature t.sub.g1 is at least 70 K.

19. The electrical feedthrough assembly according to claim 18, wherein a first glass transition temperature t.sub.g1 of the insulation element is at most 25 C. and/or wherein a second glass transition temperature t.sub.g2 of the adhesive material is higher than 100 C. and/or wherein a difference between a second glass-transition temperature t.sub.g2 and a first glass-transition temperature t.sub.g1 is at least 130 K.

20. The electrical feedthrough assembly according to claim 9, wherein the adhesive material is an epoxy adhesive selected from an amine epoxy or a bisphenol F epoxy.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0080] FIG. 1 shows an example embodiment of a feedthrough assembly comprising a base body and an insulation element in top view,

[0081] FIG. 2 shows a cross-section of the example feedthrough assembly of FIG. 1 along the line marked A-A,

[0082] FIG. 3 shows a cross-section of an example embodiment of a base body,

[0083] FIG. 4 shows a second cross-section of the base body of FIG. 3,

[0084] FIG. 5 shows a perspective view of an insulation element having three sections,

[0085] FIG. 6A shows a top view of a second embodiment of a feedthrough assembly,

[0086] FIG. 6B shows a side view with partial cross-section of the second embodiment,

[0087] FIG. 6C shows a bottom view of the second embodiment of the feedthrough assembly,

[0088] FIG. 6D shows a front view of the second embodiment,

[0089] FIG. 7 shows a third embodiment of a feedthrough assembly in a cross-sectional view, and

[0090] FIG. 8 shows a fourth embodiment of a feedthrough assembly in a cross-sectional view.

[0091] FIGS. 1 and 2 show a first exemplary embodiment of a feedthrough assembly 1. FIG. 1 shows the feedthrough assembly 1 in top view. FIG. 2 shows a cross section along a plane marked with A-A in FIG. 1. The feedthrough assembly 1 comprises a base body 10. In this exemplary embodiment, the feedthrough assembly 1 comprises three conductors 12, which are fed through the base body 10.

[0092] The base body 10 is preferably made from a metal and is configured for attachment to a housing or a part of a housing of a device such as an e-compressor (not shown). In the exemplary embodiment depicted in FIGS. 1 and 2, screw bores 15 are provided to facilitate a screw connection to a housing (not shown). Other embodiments may comprise different or additional mounting and/or alignment means for attachment of the feedthrough assembly 1 to a housing. The base body 10 as shown in FIGS. 1 and 2 is a flat piece.

[0093] As can be seen in the cross-section view of FIG. 2, each of the three conductors 12 is fed through an opening 14 in the base body 10 and is held by a fixation material 16. In the embodiment of FIGS. 1 and 2, the base body 10 has an elongated shape in which the three openings 14 are arranged along a line. Other configurations, for example where the openings 14 are evenly distributed along a circle, are also possible.

[0094] The fixation material 16 is, for example, selected from a glass and is electrically insulating. In order to further improve an electrical insulation between the base body 10 and the conductors 12, an insulation element 20 is provided. In the shown embodiment, the fixation material 16 is arranged such that it does not protrude beyond the opening 14 on the side of the base body 10 facing towards the insulation element 20. In particular, the fixation material 16 does not form a glass meniscus surrounding the conductor 12 and extending beyond the base body 10 on the side facing towards the insulation element 20. Further, in the particular embodiment shown in FIG. 2, the fixation material 16 is flush with the upper side of the base body 10. On the opposite side, the fixation material 16 protrudes from the opening 14 and forms a glass meniscus surrounding the conductor 12. Such a glass meniscus as shown in FIG. 2 can be used to provide some extension of an insulation or creepage distance. However, a further insulation element 20 could also be arranged on the opposite side the base body 10 so that one insulation element is attached to the bottom side and one is attached to the top side of the base body 10. In such a case it is preferred that the fixation material does not protrude beyond the opening 14 on both sides of the base body 10.

[0095] The insulation element 20 comprises in the shown exemplary embodiment three insulation sections 22, one for each of the conductors 12. Each of the insulation sections 22 has a cylindrical section 32, which surrounds and touches a part of the conductor 12. Further, each insulation section 22 has a top wall 34 having a conductor opening 24. The insulation element 20 is mounted to the base body 10 such that the conductors 12 are fed through the conductor openings 24. Further, as can be seen in FIG. 2, an insulation section 22 may have an extension section 34 which extends from a top wall 34 and surrounds a part of the conductor 12 in a distance.

[0096] The insulation element 20 as depicted in FIGS. 1 and 2 further comprises a sealing section 29, which is shaped like an O-ring and surrounds all insulation sections 22 of the insulation element 20. The sealing section 29 is formed as single piece together with the insulation element 20. The sealing section 29 may be used, for example, as a sealing element when the electrical feedthrough assembly 1 is mounted to a housing or a part of a housing of a device such as an e-compressor. In order to provide a good seal between the sealing section 29 and the base body 10 and/or to provide a good seal between the inner sealing section 28 and the base body 10, it is preferred to arrange a sealing area on the surface of the base body 10 in which the surface of the base body 10 is smooth and preferably free from any damages such as scratches.

[0097] For secure attachment of the insulation element 20 to the base body 10 and in order to provide additional electrical insulation, an adhesive 40 such as glue or a casting material is arranged between a bottom surface of the insulation element 20 and the fixation material 16 and a part of the base body 10. In the shown embodiment, the adhesive 40 covers the entire surface of the insulation element 20 which is facing towards the fixation material 16 and the base body 10.

[0098] In order to improve adhesion of the adhesive 40 to the base body 10, it is preferred to arrange an adhesion area on the surface of the base body 10 in which the surface of the base body 10 is roughened. The roughened surface within the adhesion area provides structures such as indentations and grooves, which increase the surface area and may even provide undercuts for improving adhesion of the adhesive 40. Further, in order to enlarge the area of the adhesive bond between the insulation element 20 and the base body 10, the insulation element 20 may have a foot section 26.

[0099] In the embodiment shown in FIGS. 1 and 2, the adhesive material 40 is not laterally restricted so that a lateral thermal expansion is possible. For such a configuration, a thickness of the adhesive material 40 of 0.1 mm to 0.6 mm has been found to minimize the amount of strain occurring due to temperature changes, in particular at the interface between the adhesive material 40 and the fixation material 16.

[0100] FIGS. 3 and 4 show a second embodiment of a base body 10 suitable for a feedthrough assembly 1 as described with respect to FIGS. 1 and 2. FIG. 3 shows a first cross section view from the side and FIG. 4 shows a second cross section view along the plane marked with C-C in FIG. 3. The base body 10 has an elongated shape similar to the base body 10 of the embodiment of FIGS. 1 and 2 and also has three openings 14 for allowing conductors 12, see FIGS. 1 and 2, to be fed through the base body 10.

[0101] In contrast to the base body 10 of FIGS. 1 and 2, the second embodiment of the base body 10 is not flat and comprises means for improving resistance against deformation such as bending. In the example depicted in FIGS. 3 and 4, the base body comprises pulled-up edges 17 as well as an elevated area 18 and a corresponding recess area 18.

[0102] The pulled-up edges 17 extend along the long sides of the elongated shape of the base body 10 and provide increased strength against deformation of the base body 10. The elevated area 18 is in this exemplary embodiment of FIGS. 5 and 6 a single area encompassing all openings 14. In an alternative embodiment, the base body could comprise several separated elevated areas 18, wherein each of the elevated areas 18 encompasses a single one of the openings 14.

[0103] The pulled-up edges 17 as well as the elevated area 18 and corresponding recess area 18 may be formed into a plate like precursor e.g. by means of a stamping process to form the base body 10. Such a stamping process provides for both the elevated area 18 as well as the recess areas 18. Although by the stamping process the elevated area 18 as well as the recess area 18 are provided, the elevated area 18 and the recess area 18 do not necessarily have a complementary geometry. Especially the form of side walls 19 of the recess area 18 and/or the elevated area 18 can be different. Furthermore, each of the measures, the pulled-up edges 17, the recess area 18 as well as the elevated area 18 provide for a higher stiffness and pressure resistance of the base body 10.

[0104] FIG. 5 shows a perspective view of the insulation element 20 of the exemplary embodiment of the electrical feedthrough assembly 1 shown in FIGS. 1 and 2.

[0105] The insulation element 20 of the exemplary embodiment has three insulation sections 22 of which the cylindrical sections 32 are clearly visible in the perspective view of FIG. 5. In further embodiments, the insulation element 20 may comprise a different number of insulation sections 22, in particular one for each conductor 12. However, it is also possible to configure an insulation section 22 such that a single insulation section 22 could accommodate more than one conductor 12, for example two, three or four conductors 12.

[0106] The insulation element 20 as depicted in FIG. 5 is configured as a single piece made from an electrical insulating material. The insulation element 20 is preferably obtained as a mold part, for example by means of injection molding. In particular, all insulation sections 22 as well as the sealing section 29, see FIGS. 1 and 2, are a single piece.

[0107] Preferably, the material of the insulation element 20 is a resilient material such as a rubber material.

[0108] FIG. 6A to 6D show a second embodiment of the electrical feedthrough assembly 1, wherein FIG. 6A shows a top view, FIG. 6B shows a side view with partial cross-section, FIG. 6C shows a bottom view, and FIG. 6D shows a front view.

[0109] The second embodiment of FIGS. 6A to 6D is similar to the embodiment described with respect to FIGS. 1 and 2, but instead of a single insulation element 20 having three insulation sections 22 three insulation elements 20 are provided and attached to the base body 10. The base body 10 is in this example made from a metal and is configured for attachment to a housing or a part of a housing of a device such as an e-compressor (not shown) and comprises screw bores 15 to facilitate a screw connection to a housing (not shown). The base body 10 is a flat piece but could alternatively be configured to comprise elevations and/or depressions, just as shown in FIGS. 3 and 4.

[0110] As can be seen in the cross-section view of FIG. 6B, each of the three conductors 12 is fed through an opening 14 in the base body 10 and is held by a fixation material 16. The fixation material 16 is, for example, selected from a glass and is electrically insulating. In the embodiment of FIGS. 6A to 6D, each of the conductors 12 is provided with an insulation element 20 having a single insulation section. At least on the side facing towards the insulation elements, the fixation material 16 is arranged such that it does not protrude beyond the opening 14 on the side of the base body 10.

[0111] In the example depicted in FIGS. 6A to 6D, each of the insulation sections 22 of the insulation elements 20 are provided with annular ribs 38 configured to form a form-fit connection with a connector that may be slid over the respective conductor 12 to form an electrical connection. By means of the annular ribs 38, such a connector may be secured in place. Further, the annular ribs 38 provide a seal to prevent dirt or fluids from entering the space between a connector and the conductor 12 and/or the insulation section 22.

[0112] For secure attachment of the insulation elements 20 to the base body 10 and in order to provide additional electrical insulation, an adhesive 40 such as glue or a casting material is arranged between a bottom surface of the insulation element 20 and the fixation material 16 and a part of the base body 10. In order to enlarge the area of the adhesive bond between the insulation elements 20 and the base body 10, the insulation element 22 of FIGS. 6A to 6D have a foot section 26. In order to reduce the risk that adhesive material 40 flows onto sealing surfaces of the base body 10, the base body 10 comprises pockets 50 surrounding the respective conductor 12 for receiving the adhesive material 40.

[0113] In the embodiment shown in FIGS. 6A to 6D, the adhesive material 40 is laterally restricted by sidewalls of the pockets 50 so that a lateral thermal expansion is restricted. For such a configuration, a thickness of the adhesive material 40 of 0.3 mm to 1 mm has been found to minimize the amount of strain occurring due to temperature changes, in particular at the interface between the adhesive material 40 and the fixation material 16.

[0114] FIG. 7 shows a third embodiment of the feedthrough assembly 1 in a cross-sectional view.

[0115] The base body 10 is similar to the base body described with respect to FIG. 3 but does not feature the pulled-up edges 17. The feedthrough assembly of the third exemplary embodiment comprises three insulation elements 20, each having a single insulation section 22. Each of the insulation sections 22 is arranged to surround one of the conductors 12 in order to extend an insulation distance between the respective conductor 12 and the base body 10. In order to further enhance the insulation distance or creepage distance, the top wall 34 of the insulation sections 22 is provided with a groove 39.

[0116] The insulation elements are affixed to the fixation material 16 by means of the adhesive material 40. The fixation material 16 and a part of the base body 16 are configured to form a pocket 50 which receives the adhesive material 40. The side walls 52 of the pocket 50 serve as a barrier to prevent any excess adhesive material 40 from flowing onto other areas of the base body, in particular onto areas serving as sealing areas.

[0117] In the third exemplary embodiment, the side walls 52 of the pockets 50 are slanted or chamfered. In the depicted example, an angle between the side wall 52 and the surface of the fixation material is about 135. Such a chamfered or slanted side wall still serves as a flow boundary and restricts lateral thermal expansion, but allows air bubbles within the adhesive material to escape.

[0118] FIG. 8 shows a fourth exemplary embodiment of the feedthrough assembly 1 which is similar to the first embodiment described with respect to FIGS. 1 and 2. The fourth embodiment differs from the first embodiment in the configuration of the insulation element 20.

[0119] The insulation element 20 of the fourth embodiment has an extension section 36 surrounding the at least one conductor 12 in a distance such that a gap 37 is formed. This gap 37 allows receiving of a connector for establishing an electrical connection with the conductor 12. Annular rings 38 are arranged on a wall of the extension section 36 facing towards the at least one conductor 12. The annular rings 38 serve as sealing means to seal the space between the insulation element 20 and the connector.

[0120] Although the present invention has been described with reference to preferred examples of embodiments, it is not limited thereto but can be modified in a variety of ways.

LIST OF REFERENCE NUMERALS

[0121] 1 electrical feedthrough assembly [0122] 10 base body [0123] 12 conductor [0124] 14 opening [0125] 15 screw bore [0126] 16 fixation material [0127] 17 pulled up edge [0128] 18 elevated area [0129] 18 recess area [0130] 19 side wall of opening [0131] 20 insulation element [0132] 22 insulation section [0133] 24 conductor opening [0134] 26 foot section [0135] 29 seal section [0136] 32 cylindrical section [0137] 34 top wall [0138] 36 extension section [0139] 37 gap [0140] 38 annular ribs [0141] 39 groove [0142] adhesive [0143] 50 pocket [0144] 52 side wall of pocket