Patent Description:
Housings for electronic components usually require a plurality of electrical feedthroughs in order to enable electrical connections from outside to the inner part of the housing, which accommodates e.g. parts of an electronic compressor in the housing. The electrical feedthroughs should be fluid tight or even hermetic in order to protect the components inside the housing from the environment and/or to contain gases or fluids in the housing. In order to provide such fluid-tight or hermetic feedthroughs for an electric conductor arranged in an opening of the housing, glass-to-metal seals may be used. A fixation material, for example a glass material, is used to seal the opening and to hold the conductor within the opening. The fixation material also provides an electrical insulation between the conductor and the housing.

In order to provide additional electrical insulation between the housing and the conductor and, if more than one conductor is present between the conductors, it is known to arrange an additional insulation element on the electrical feedthrough. The insulation element at least partially surrounds the conductor and enlarges a so-called creepage distance between a conductor and the housing and/or between two conductors. The insulation element for extending the creepage distance may be, for example, a rubber or plastic sleeve, which at least partially surrounds a conductor.

For connecting such an insulation element to the feedthrough, in particular to a base body of the feedthrough, it is known to use injection molding, wherein the insulation element is directly molded onto the base body. International patent application <CIT> discloses a housing part comprising a feedthrough. The feedthrough comprises a base body and a conductor which is fed through an opening of the base body. A glass material is provided to hold the conductor in the opening and to electrically insulate the conductor from the base body. A plastic, rubber and/or elastic material is directly molded onto the feedthrough and at least partially encloses a conductor of the feedthrough so that the risk for a short circuit in case of the presence of a water film is reduced.

Direct molding allows for tight connection between a base body of the feedthrough and the insulation element. However, specialized molding tools are required for each feedthrough type, as the half-finished feedthrough must be inserted into the mold. Also, any casting burr must be removed after molding. Still further, the molding tools as well as the material injected into the mold will exert forces onto the feedthrough, in particular onto the fixation material, which may damage the feedthrough and may be a cause of low yield of good feedthrough elements.

Such additional insulating elements may also be prepared as separate parts and can then be attached to the glass-to-metal-seal feedthrough, for example by means of an epoxy-glue. Glue is applied onto the insulting element and/or onto the feedthrough and then the insulating element is placed onto the feedthrough, wherein the conductor(s) slide through openings of the insulating element. However, it is difficult to reliably apply the correct amount of glue such that the insulating element is securely attached without any gaps in the glue and without excess glue overflowing onto other parts of the feedthrough. Overflowing glue may block parts of the feedthrough assembly required for mounting to a housing or may cover parts of the conductor which are intended to make electrical contact, for example with a connector. Further, any corrections to an alignment between the parts must be completed before the glue has cured.

<CIT> discloses a sealed terminal device for a motor-driven compressor comprising an insulating element. The insulating element includes a groove or a cavity to increase a creepage distance for insulation between two terminals.

It is an object of the present invention to provide a feedthrough assembly having at least one sealed conductor and an additional insulation element for extending of a creeping distance between the conductor and a base body of the feedthrough, which is easy to manufacture and has a secure and reliable connection between the insulation element and the base body.

An electrical feedthrough assembly is proposed, preferably configured as an e-compressor terminal, especially in form of a plate like element, for the attachment to a housing, preferably a housing of an e-compressor. The feed through assembly comprises a base body with at least one opening for at least one conductor embedded in a fixation material that is fed into each of the respective openings and thus sealing the respective opening.

The electrical feedthrough assembly further comprises at least one insulation element affixed to the base body, the insulation element having at least an insulation section for a conductor, the insulation section having an conductor opening through which the respective conductor is fed, the insulation element being configured and arranged such that a cavity is formed between the base body and the insulation section. The insulation section further comprises at least one further opening allowing access to the cavity, the cavity being at least partially filled with an adhesive for forming a connection between the base body and the insulation section of the insulation element.

The proposed cavity serves as a confinement for the adhesive. The adhesive is in particular confined to a space comprising the exposed surface of the fixation material and portions of the surfaces of the base body, the conductor and the insulation element.

Preferably, the cavity is completely filled with the adhesive. Further, the adhesive in the cavity is particularly preferably free from any air bubbles trapped inside the adhesive. The at least one further opening is configured to allow access to the inside of the cavity from the outside and thus enables introduction of the adhesive into the cavity. In order to compensate for manufacturing tolerances, the volume provided by one or more further openings may be used as a reservoir for receiving any excess adhesive after the cavity has been completely filled. Accordingly, the number and size of the further openings is preferably configured to provide a sufficiently large reservoir volume.

The insulation element is preferably arranged over the conductors such that the cavity at least partially surrounds the respective conductor.

In case more than one conductor is fed through the base body, the feedthrough assembly may comprise one insulation element comprising individual conductor opening for each of the conductors. Alternatively, the feedthrough assembly may comprise more than one insulation element, wherein each of the insulation elements has respective insulation sections with conductor openings for a certain number of conductors, for example two or three conductors, or has a single conductor opening for a single conductor. In the latter case, the number of insulation elements corresponds to the number of conductors.

Similarly, an insulation section of the insulation element may have a single conductor opening for a single conductor or may have several, e.g. two or three conductor openings and may thus accommodate several conductors, one conductor per conductor opening.

Preferably, a wall of the conductor opening touches the respective conductor. It is particularly preferred that the wall of the conductor opening creates a seal with the conductor so that the cavity is sealed with respect to the conductor.

Preferably, the insulation element has at least one inner sealing section touching the base body so that the formed cavity is sealed against the surface of the base body. Particularly preferably, the insulation section has a cylindrical portion having an inner sealing section touching the base body, thereby sealing each formed cavity against the respective surface of the base body. Thus, any overflow of adhesive introduced into the cavity onto neighboring portions of the base bodies surface is avoided.

Preferably, the cavity of the insulation section comprises a top wall, which is preferably arranged parallel to a top surface of the base body, wherein the top wall comprises the conductor opening and the at least one further opening.

Preferably, each formed cavity has <NUM> to <NUM>, preferably <NUM> to <NUM>, especially preferably <NUM> to <NUM> further openings. In case an insulation section has exactly one cavity, the insulation section accordingly comprises <NUM> to <NUM>, preferably <NUM> to <NUM>, especially preferably <NUM> to <NUM> further openings. Preferably, the further openings are symmetrically arranged around the conductor opening.

The insulation element is preferably configured to provide a sealing function so that the insulation element may serve as a sealing element between the base body of the feedthrough assembly and e.g. a housing or a housing part of a device such as an electric compressor. Accordingly, it is preferred that the insulation element comprises an outer sealing section, which surrounds all insulation sections of the insulation element and is configured to touch the base body. Preferably, the outer sealing section has an O-ring like shape. Further, it is preferred to form the outer sealing section as single piece together with the insulation element. Alternatively to arranging a single outer sealing section which surrounds all insulation sections, each of the insulation sections may be provided with a respective outer sealing section which may have an O-ring like shape. This is in particular useful for embodiments in which a separate insulation element is arranged for each of the individual conductors. In such cases, the outer sealing section may also serve as inner sealing section to seal the cavity against the base body.

Suitable materials for the insulation element may be selected from resilient material. Preferred resilient materials include in particular natural or synthetic rubbers, in particular fluoroelastomers, ethylene propylene diene monomer (EPDM) rubbers, hydrogenated nitrile-butadiene rubbers (HNBR) and silicone rubbers.

Further suitable materials for the insulation element include thermoplastic or thermosetting plastic materials.

With respect to a housing of an electrical compressor, to which the electrical feedthrough assembly may be attached, the insulation element may be arranged on the side facing towards the outside of the housing. Additionally or alternatively, the insulation element may be arranged on the side facing towards the inside of the housing. In particular, the assembly may comprise two insulation elements, one arranged on the outside facing side and one on the inside facing side.

For example, when the proposed electrical feedthrough assembly is connected to a housing of an electric compressor, it is preferred to use a silicone rubber for an insulation element on the side of the assembly facing towards the inverter. For insulation elements facing towards the motor side, it is preferred to use a HNBR rubber.

In principle, the adhesive may be selected from any known electrically insulating adhesive material. However, the adhesive is preferably an epoxy adhesive. Further, electrically insulating casting materials may be used as adhesive.

The fixation material is preferably selected from a glass, a ceramic or a glass ceramic material. Preferably, the fixation material is a glass material so that a glass-to-metal seal (GTMS) is provided between the base body, the conductor and the fixation material.

It is preferred that the fixation material is arranged such that the fixation material does not extend beyond the at least one opening in the base body, at least on the side facing towards the insulation element. In particular, a glass meniscus surrounding the conductor and extending beyond the base body should be avoided.

Arranging the fixation material such that it does not extend beyond the base body allows bending of the conductors without damaging the fixation material. For example, when a glass material is used as fixation material, a formed glass meniscus surrounding the conductor and extending beyond the opening would be subject to strong forces when the conductor is bent which could lead to cracks or damages to the glass. Thus, the proposed arrangement of the fixation material allows bending of the conductors as required. Further, the shape of such a glass meniscus is subject to strong variation making it difficult to determine the correct amount of adhesive.

Preferably, the material of the base body is a metal. More preferably, the base body comprises as a material steel, especially stainless steel, most preferred structural steel, preferably microalloyed steel, most preferred structural steel in form of microalloyed steel. Microalloyed steel is a type of alloy steel that contains small amounts of alloying elements (<NUM>,<NUM> to <NUM>,<NUM> %), including niobium, vanadium, titanium, molybdenum, zirconium, boron and rare-earth metals. They are used to refine the grain microstructure or facilitate precipitation hardening. The yield strength of microalloyed steel is between <NUM> and <NUM> MPa without heat treatment. Weldability is good, and can even be improved by reducing carbon content while maintaining strength. Fatigue life and wear resistance are superior to similar heat-treated steels. Cold-worked microalloyed steels do not require as much cold working to achieve the same strength as other carbon steel; this also leads to greater ductility. By using microalloyed steel as material, a high bending stiffness and strength could be provided.

Preferably, the base body, the least one conductor and the fixation material form a compression seal. Accordingly, a first coefficient of thermal expansion of the base body is preferably chosen to be larger than a second coefficient of thermal expansion of the fixation material. Preferably, for obtaining a compression seal, a difference between the first coefficient of thermal expansion is at least <NUM> ppm/K and more preferably the difference between the first coefficient of thermal expansion is at least <NUM> ppm/K. A third coefficient of thermal expansion of the conductor material is preferably chosen to be about equal to or less than the second coefficient of thermal expansion of the fixation material. Two coefficients of thermal expansion are considered to be about equal if the difference is less than <NUM> ppm/K.

Alternatively to a compression seal, the material of the base body, the fixation material and the conductor material may be chosen such that their respective coefficients of thermal expansion are about equal, wherein a difference of less than <NUM> ppm/K is considered to be about equal.

Preferably, the formed seal between the opening of the base body, the fixation material and the conductor is a hermetical seal. In particular a feedthrough having a He leakage rate of better than <NUM>•<NUM>-<NUM> mbar I/s, especially <NUM>•<NUM>-<NUM> mbar l/s for a pressure difference of <NUM> bar is considered to be hermetic.

Preferably, a part of the surface of the base body, in particular a part of the surface of the base body defining a wall of the cavity, is configured as an adhesion area having a roughness e.g. provided by a stamping or an embossing process for enhancing adhesion of the adhesive. The adhesion area may in particular define a wall of the cavity. The roughness can also be provided by a rolled textured sheet material or by a rolled texture with a stamping step by a tool. Due to the good adhesion a connection between the material of the base body and the adhesive is improved. Additionally or alternatively, structures such as tenons and/or pins and/or spigots can be provided within the adhesion area. Further, structures such as a ring embossing and/or ring shaped grooves can be formed to improve the adhesion. Such tenons can be formed from the sheet, eventually in form of a mushroom shaped head part. A ring embossing around the fixation material in which the conductor is fed through the base body would be possible. In any case by the structure of the surface of the base body within the adhesion area, the connection of adhesive to the base body can be improved. In addition or alternatively to structuring a part of the surface of the base body it is also conceivable to provide such structures on parts of the surface of the insulation element.

Preferably, a part of the surface of the base body, in particular a part of the surface arranged adjacent to the inner sealing section or the outer sealing section of the insolation element, is configured as a sealing area. In the sealing area, it is preferred that the surface of the base body is smooth and flat. In particular, it is preferred that within the sealing area the surface of the base body has a flatness according to DIN ISO <NUM> of at least <NUM>, preferably at least <NUM>, most preferably from <NUM> to <NUM>. Such a smooth and/or flat area facilitates creating a good and tight seal. A surface roughness is preferably Rz<NUM> or better.

Preferably, the base body of the feedthrough assembly comprises mounting means to facilitate attaching of the feedthrough assembly to a housing or housing part of a device, such as an electric compressor. Preferably, the mounting means are configured as attachment bores or screw bores, wherein the base body preferably comprises at least two of said bores. The base body may additionally or alternatively comprise centering means such as protrusions or indentations to facilitate exact placement of the base body and thus of the feedthrough assembly with respect to a housing or part of a housing of a device.

The base body may be configured to have an elongated shape in which all the openings for the conductors are arranged along a line. However, other configurations, for example a round base body where the openings are evenly distributed along a circle, are also possible.

Preferably, the base body comprises means for improving resistance against deformation such as bending. In one embodiment, the base body may comprise a pulled up edge, which fully or partially surrounds the base body. In case the base body has an elongated shape, it is preferred to arrange pulled up edges on the long sides of the base body.

The pulled up edge and the base body may be configured as a single part or the pulled up edge may be configured as a separate part, which could be joined with the base body by fusing. The advantage of the pulled up edge to be a separate part is that production of both parts - base body and pulled up edge - could be organized separately.

However, in an alternative embodiment, the base body is reshaped in order to provide the pulled up edge. Such a reshaping process could be e.g. stamping a plate like precursor element in order to form the base body.

The pulled up edge is in both embodiments a part arranged along an edge of the base body and is thus not interfering with the openings of the base body or a sealing area arranged on a surface of the base body.

Additionally or alternatively, the base body may comprise one or more elevated area(s) and/or one or more recess area(s). Such an elevated area may be a single area encompassing all openings of the base body. In an alternative embodiment, the base body could comprise several separated elevated areas, wherein each of the elevated areas encompasses a single one of the openings.

The elevated area(s) and recess area(s) may, for example be formed into a plate like precursor of the base body e.g. by means of a stamping process to form the base body.

The insulation element increases an electrical insulation distance or creeping distance between a conductor and the base body and/or between two conductors. Thus, the insulation element contributes to reduce the risk of short circuits, especially in case of wet or humid environments. In such environments, a water layer and/or dirt layer or the like might deposit on the surfaces of the feedthrough assembly, in particular on a surface of the fixation material insulating a conductor from the base body. Such a water film wetting the materials of the feedthrough assembly can in particular occur easily in an e-compressor with the feedthrough assembly configured as an e-compressor terminal. This is because the e-compressor has a very low temperature e.g. of lower than e.g. <NUM> or even negative temperatures, whereas the ambient temperature e.g. in the summer time might be higher than <NUM>. In such a case, a water film may form due to condensation. By additionally insulating the conductor from the material of the base body and thus from a housing of a device comprising the feedthrough assembly, for example in e-compressor applications, short circuits due to conductive water and/or dirt films can be prevented.

Using an adhesive for mounting the insulation element allows the insulation element to be prepared as a separate part. In contrast to known adhesive attachments of known insulation elements, the proposed cavity and the sealing of the cavity by means of the inner sealing section confines the adhesive material to a defined space and avoids any spilling or overflow of the adhesive onto sensitive areas of the feedthrough assembly. In particular, areas intended for creating a tight seal, such as a sealing area of the base body, as well as portions of the conductor intended for establishing a good electrical contact remain free from any undesired contamination with the adhesive.

Preferably, the cylindrical section of the insulation element has an extension portion, which extends beyond the top wall. Preferably, the extension portions surrounds the conductor at a distance and extends an insulation distance or creeping distance further. The extension portion may be provided with ribs, ridges or grooves configured to form a form-fit connection with a connector that may be slid over the conductor to form an electrical connection. By means of the ridges or grooves, such a connector may be secured in place. Further, the ribs, ridges or grooves may provide a seal to prevent dirt or fluids from entering the space between the conductor and the extension portion when a connector is attached. The ribs, rings, ridges and/or grooves can be arranged such that an annular ring or groove is formed. Preferably, such ribs, rings, ridges or grooves are arranged on the side of the extension portion facing towards the conductor, thus allowing sealing any gap between the insulation element and a connector. Additionally or alternatively, the extension portion may be provided with ribs, in particular in the form of one or more annular rings, ridges or grooves arranged on the outside facing wall. It is also possible to arrange set-in-rings over the outside facing wall of the extension portions. Such a set-in-ring may, for example, be secured in a groove arranged in the outside facing wall of the extension portion.

In one embodiment of the invention, further insulation to the conductors is only provided on one side of the feedthrough assembly, for example on a bottom side of the base body. Alternatively, insulation elements may be arranged and attached to the base body on both sides, e.g. an upper side and a bottom side, so that both sides of the fed through conductors are protected by insulation elements. Both insulation elements may be attached and fixed to the base body as described herein by means of an adhesive material located within a cavity defined by the base body and the insulation element.

A further aspect of the invention relates to a method for manufacturing of such an electrical feedthrough assembly. In a first step, an electrical feedthrough assembly is provided. The base body assembly comprises a base body having at least one conductor embedded in fixation material that is fed through an opening of the base body providing a glass-to-metal seal (GTMS). If required, the surfaces of the base body can be cleaned or pretreated to improve adhesion.

In a subsequent second step, at least one insulation element is provided and placed onto the base body such that the at least one conductor is fed through a conductor opening of an insulation section of the insulation element. Further, the insulation element is configured and arranged such that a cavity is formed between the base body and the insulation section. As no adhesive material is present, yet, there is no time restriction, for example by a cure time, for carefully placing and aligning the base body and the insulation element.

In a subsequent third step, an adhesive is injected into the cavity. Preferably, the adhesive is injected into the cavity through at least one further opening in the insulation element allowing access to the cavity. For example, an injection needle may be introduced into one of the further openings for injecting the adhesive into the respective cavity. The cavity is at least partially filled with adhesive in this step. Preferably, the cavity is completely filled with the adhesive and in particular does not comprise air bubbles. In order to allow venting of air, it is preferred that the insulation element has more than one further opening allowing access to the cavity.

During the injection of the adhesive, the insulating element is preferably pressed against the base body in order to ensure that an inner sealing section of the insulation element is firmly touching the base body and seals the cavity against the base body. After injection of the adhesive, the adhesive is cured.

Preferably, the cavity is completely filled with the adhesive. In order to compensate for manufacturing tolerances, the volume provided by the further openings may be used as a reservoir for receiving any excess adhesive after the cavity has been completely filled. For example, a set dosage volume of the adhesive may be chosen such that in average the volume provided by the further openings is half filled with the adhesive.

Introduction of the adhesive is preferably performed such that no air bubbles remain trapped within the cavity so that the adhesive inside the cavity is free from any voids or bubbles. This may be achieved by keeping at least one of the further openings of each insulation section open during the introduction of the adhesive so that air contained in the cavity may vent out of the cavity through the respective further opening.

The proposed injection of the adhesive material into the defined cavity has the particular advantage that the adhesive material is confined to the space inside the closed cavity and cannot flow freely. This allows the use of adhesive materials without the usual limitations to adhesives having high viscosities. Adhesives having relatively low viscosities can be more precisely dosed and any remaining air bubbles can more easily be removed so that a gap-free and bubble-free adhesive film covering at least the entire surface of the base body and the fixation material exposed within the cavity may be obtained. Thus, a reliable electrical insulation is ensured. Additionally, it is no longer required to apply the adhesive before the insulation element is brought into contact with the base body as the proposed further openings allow direct access to the cavity intended for receiving the adhesive. Accordingly, the two parts may be brought into contact and may be carefully adjusted into the correct relative position without any restrictions by a cure time of an adhesive as in the proposed method the adhesive is only introduced into the cavity after the parts have been correctly placed and aligned. All cavities may be filled simultaneously with the adhesive e.g. by providing at least one injection needle per cavity.

In an optional subsequent fourth step, curing of the adhesive may be performed and/or accelerated by subjecting the formed feed through to heat and/or radiation suitable for curing the adhesive.

The electrical feedthrough assembly described herein is particularly suited for use as a connection terminal for an electric compressor. The feedthrough assembly may be configured as part of a housing of the electric compressor or may be attached to a housing or a part of a housing for an electric compressor.

Accordingly, it is a further aspect of the invention to provide an electric compressor comprising one of the electrical feedthrough assemblies described herein.

It is to be understood that the features mentioned above and those to be explained below can be used not only in the combination indicated in each case, but also in other combinations or alone, without leaving the scope of the present invention.

Preferred embodiments of the invention are shown in the figures and will be explained in more detail in the following description, wherein identical reference signs refer to identical or similar components or elements.

<FIG> show an exemplary embodiment of a feedthrough assembly <NUM>. <FIG> shows the feedthrough assembly <NUM> in bottom view. <FIG> shows a first cross section along a plane marked with A-A in <FIG> and <FIG> shows a second cross section along a plane marked with B-B in <FIG>. The feedthrough assembly <NUM> comprises a base body <NUM>. In this exemplary embodiment, the feedthrough assembly <NUM> comprises three conductors <NUM>, which are fed through the base body <NUM>.

The base body <NUM> 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 <FIG>, screw bores <NUM> 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 <NUM> to a housing. The base body <NUM> as shown in <FIG> is a flat piece.

As can be seen in the cross-section views of <FIG> and <FIG>, each of the three conductors <NUM> is fed through an opening <NUM> in the base body <NUM> and is held by a fixation material <NUM>. The fixation material <NUM> is, for example, selected from a glass and is electrically insulating. Further, the fixation material <NUM> is arranged such that it does not protrude beyond the opening <NUM>. In particular, the fixation material <NUM> does not form a glass meniscus surrounding the conductor <NUM> and extending beyond the base body <NUM>. In the embodiment of <FIG>, the base body <NUM> has an elongated shape in which the three openings <NUM> are arranged along a line. Other configurations, for example where the openings <NUM> are evenly distributed along a circle, are also possible.

In order to further improve an electrical insulation between the base body <NUM> and the conductors <NUM>, an insulation element <NUM> is provided. In the exemplary embodiment of <FIG>, the insulation element <NUM> is attached to a bottom side of the base body <NUM>. However, the insulation element <NUM> could also be arranged on a top side of the base body <NUM> and it is also possible to provide two insulation elements <NUM>, one attached to the bottom side and one attached to the top side of the base body <NUM>.

The insulation element <NUM> comprises in the shown exemplary embodiment three insulation sections <NUM>, one for each of the conductors <NUM>. Each of the insulation sections <NUM> has a cylindrical section <NUM>, which surrounds a part of the conductor <NUM> in a distance. Further, each insulation section <NUM> has a top wall <NUM> having a conductor opening <NUM>. The insulation element <NUM> is mounted to the base body <NUM> such that the conductors <NUM> are fed through the conductor openings <NUM>.

A cavity <NUM> is defined in a space between the top wall <NUM> and a bottom surface of the base body <NUM>. A part of the cylindrical section <NUM> of the insulation section <NUM> forms a side wall of said cavity <NUM> and the conductor <NUM> is fed through the cavity <NUM>. At the interface between the part of the cylindrical section <NUM> forming a side wall of the cavity <NUM> and the bottom surface of the base body <NUM>, an inner sealing section <NUM> is arranged. The inner sealing section <NUM> is shaped similar to an O-ring and is formed as single piece together with the insulation element <NUM>. The inner sealing section <NUM> provides a seal between the cylindrical section <NUM> of the insulation section <NUM> and thus seals the cavity <NUM> in the direction of the base body <NUM>.

The insulation element <NUM> as depicted in <FIG> further comprises an outer sealing section <NUM>, which is shaped like an O-ring and surrounds all insulation sections <NUM> of the insulation element <NUM>. The outer sealing section <NUM> is formed as single piece together with the insulation element <NUM>. The outer sealing section <NUM> may be used, for example, as a sealing element when the electrical feedthrough assembly <NUM> 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 outer sealing section <NUM> and the base body <NUM> and/or to provide a good seal between the inner sealing section <NUM> and the base body <NUM>, it is preferred to arrange a sealing area <NUM> on the surface of the base body <NUM> in which the surface of the base body <NUM> is smooth and preferably free from any damages such as scratches.

The insulation sections <NUM> of the exemplary embodiment further comprise an extension portion <NUM> so that the cylindrical section <NUM> extends beyond the top wall <NUM> defining the cavity <NUM>. The extension portions <NUM> surrounds the conductor <NUM> at a distance and extends an insulation or creeping distance further. The extension portion <NUM> may be provided with ribs or ridges <NUM> configured to form a form-fit connection with a connector that may be slid over the conductor <NUM> to form an electrical connection. By means of the ridges <NUM>, such a connector may be secured in place. Further, the ridges <NUM> may provide a seal to prevent dirt or fluids from entering the space between the conductor <NUM> and the extension portion <NUM> when a connector is attached.

For secure attachment of the insulation element <NUM> to the base body <NUM> and in order to provide additional electrical insulation, an adhesive <NUM> such as glue or a casting material fills the cavity <NUM>. In the shown exemplary embodiment, the adhesive <NUM> fills the entire cavity <NUM>. The adhesive <NUM> has been introduced into the cavity after placement of the insulation element <NUM> onto the base body <NUM> and thus after formation of the cavity <NUM> through a further opening <NUM> in the top wall <NUM> of the insulation section <NUM>. In the exemplary embodiment of <FIG>, each insulation section <NUM> has four further openings <NUM>, which allow direct access to the cavity <NUM> from the outside. For example, one or more needles may be inserted through one or more of the further openings <NUM> to inject the adhesive <NUM> into the cavity <NUM>. Introduction of the adhesive <NUM> is carried out for each of the insulation sections <NUM> and thus for each of the cavities <NUM> so that the insulation element <NUM> is securely attached and insulated. Introduction of the adhesive <NUM> can be performed simultaneously for all insulation sections <NUM>, for example by providing multiple injection needles. Preferably, at least one of the further openings <NUM> of each insulation section <NUM> remains open during the introduction of the adhesive <NUM> so that air contained in the cavity <NUM> may vent out through the respective further opening <NUM>. This allows for a bubble-free filling of the cavity <NUM>.

In order to improve adhesion of the adhesive <NUM> to the base body <NUM>, it is preferred to arrange an adhesion area <NUM> on the surface of the base body <NUM> in which the surface of the base body <NUM> is roughened. The roughened surface within the adhesion area <NUM> provides structures such as indentations and grooves, which increase the surface area and may even provide undercuts for improving adhesion of the adhesive <NUM>.

The cavity <NUM> can be filled partially or completely with the adhesive <NUM>. In case of a partial fill, sufficient adhesive <NUM> is injected to cover the surface of the base body <NUM>, the exposed surface of the fixation material <NUM> and parts of the surfaces of the cylindrical section <NUM> forming the sidewall of the cavity <NUM> as well as a part of the surface of the conductor <NUM>. The remaining part of the volume of the cavity <NUM> can serve as a reservoir to compensate for tolerances in the dosing of the adhesive <NUM>. Preferably, the cavity <NUM> is completely filled with the adhesive <NUM>. In this case, the volume of the further openings <NUM> serves as a reservoir for any excess adhesive <NUM>. An overflow of adhesive <NUM> out of the space defined by the cavity <NUM> can thus be avoided. In particular, the sealing area <NUM> of the base body <NUM> as well as the electrical conductor <NUM> in the region of the extension portion <NUM> are not covered by adhesive <NUM>. The sealing area <NUM> can thus provide a smooth surface suitable for forming a seal and the surface of the portion of the electrical conductor <NUM> located within the extension portion <NUM> is suitable for forming a reliable electrical contact.

<FIG> shows a perspective view of the insulation element <NUM> of the exemplary embodiment of the electrical feedthrough assembly <NUM> shown in <FIG>.

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

The insulation element <NUM> as depicted in <FIG> is configured as a single piece made from an electrical insulating material. The insulation element <NUM> is preferably obtained as a mold part, for example by means of injection molding. In particular, all insulation sections <NUM> as well as the outer sealing section <NUM> as well as the inner sealing section <NUM>, see <FIG> and <FIG>, are a single piece.

Preferably, the material of the insulation element <NUM> is a resilient material such as a rubber material. However, other electrically insulating materials such as thermoplastic or thermosetting plastic materials are also possible.

<FIG> show a second embodiment of a base body <NUM> suitable for a feedthrough assembly <NUM> as described with respect to <FIG>. <FIG> shows a first cross section view from the side and <FIG> shows a second cross section view along the plane marked with C-C in <FIG>. The base body <NUM> has an elongated shape similar to the base body <NUM> of the embodiment of <FIG> and also has three openings <NUM> for allowing conductors <NUM>, see <FIG>, to be fed through the base body <NUM>.

In contrast to the base body <NUM> of <FIG>, the second embodiment of the base body <NUM> is not flat and comprises means for improving resistance against deformation such as bending. In the example depicted in <FIG>, the base body comprises pulled up edges <NUM> as well as an elevated area <NUM> and a corresponding recess area <NUM>'.

The pulled up edges <NUM> extend along the long sides of the elongated shape of the base body <NUM> and provide increased strength against deformation of the base body <NUM>. The elevated area <NUM> is in this exemplary embodiment of <FIG> a single area encompassing all openings <NUM>. In an alternative embodiment, the base body could comprise several separated elevated areas <NUM>, wherein each of the elevated areas <NUM> encompasses a single one of the openings <NUM>.

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

<FIG>show an embodiment of the electrical feedthrough assembly <NUM> having individual insulation elements <NUM> for each of the conductors. <FIG> shows a top-view, <FIG> shows a front-view with partial cross-section, <FIG> shows a bottom view and <FIG> a side view.

The base body <NUM> is in this embodiment configured as a flat elongated plate with two parallel straight sides and two curved sides. The base body <NUM> comprises two screw bores <NUM> and three openings <NUM>. The electrical feedthrough assembly <NUM> of <FIG> comprises three conductors <NUM>, wherein each conductor <NUM> is fed through one of the openings <NUM> and is held within the respective opening <NUM> by means of a fixation material <NUM>.

As can best be seen in <FIG>, the fixation material <NUM> is arranged such that it does not extend beyond the respective opening <NUM> on the top-facing side. On the bottom-facing side, the fixation material <NUM> extends beyond the respective opening <NUM> and forms a meniscus around the respective conductor <NUM>.

In the embodiment of <FIG>, the electrical feedthrough assembly <NUM> comprises three insulation elements <NUM>, wherein each if the insulation elements <NUM> has a single insulation section <NUM>, each associated with one of the conductors <NUM>.

Around each of the openings <NUM>, the base body <NUM> has a recess area <NUM>', which is shaped and arranged such that one of the insulation elements <NUM> is partially received within the formed recess. Walls of the recess area <NUM>' and an outer sealing section <NUM> of an insulation element <NUM> form a seal so that within the insulation section <NUM> a cavity <NUM> is formed surrounding a conductor <NUM>.

The shape of the insulation section <NUM> of an insulation element <NUM> is similar to the embodiment described with respect to <FIG>, but the extension portion <NUM> of the embodiment of <FIG>does not feature annular grooves <NUM> located on the inwards facing wall. Instead, the embodiment of <FIG>has annular ribs <NUM> arranged on the outward facing wall. In further embodiments it is possible to arrange grooves and/or ribs <NUM> on both the outside and the inside facing walls of the extension portion <NUM>.

<FIG>show an embodiment of a feedthrough assembly <NUM> comprising set-in-rings. The embodiment of <FIG> corresponds to the embodiment described with respect to <FIG>, except for the configuration of the annular ribs <NUM>. In the embodiment of <FIG>, set-in-rings are arranged in corresponding grooves in the outer wall of the extension portions <NUM>. Such an arrangement allows the use of a material for the annular rubs <NUM> which is different from the material of the cylindrical wall forming the extension portion <NUM>.

Claim 1:
Electrical feedthrough assembly (<NUM>) comprising a base body (<NUM>), for the attachment to a housing, with at least one opening (<NUM>) for at least one conductor (<NUM>) embedded in a fixation material (<NUM>) that is fed into each of the respective openings (<NUM>) and sealing the respective opening (<NUM>), wherein
said electrical feedthrough assembly (<NUM>) further comprises
at least one insulation element (<NUM>) affixed to the base body (<NUM>), the insulation element (<NUM>) having at least an insulation section (<NUM>) for a conductor (<NUM>), the insulation section (<NUM>) having an conductor opening (<NUM>) through which the respective conductor (<NUM>) is fed, the insulation element (<NUM>) being configured and arranged such that a cavity (<NUM>) is formed between the base body (<NUM>) and the insulation section (<NUM>), characterized in that the insulation section (<NUM>) further comprises at least one further opening (<NUM>) allowing access to the cavity (<NUM>), the cavity (<NUM>) being at least partially filled with an adhesive (<NUM>) for forming a connection between the base body (<NUM>) and the insulation section (<NUM>) of the insulation element (<NUM>).