DE102013006623A1 - Cooling jacket for an electric machine and method for producing an electrical machine with a cooling jacket - Google Patents

Abstract

The invention relates to a cooling jacket (1) for an electrical machine, which consists of at least two parts (3, 4) which together delimit a cavity (7) which is designed like a channel for a cooling fluid, the at least two parts (3, 4) 4) have mutually facing sealing surfaces (14) which enclose an intermediate space and at least one of which serves to receive an elastic sealing element (9). According to the invention, a sealing element (9) is arranged on one of the sealing surfaces (14) in an assembled state, the extent of the sealing element (9) in the radial direction to the axis of rotation of the electrical machine being less than the intermediate space and the sealing element (9 ) expanded in a state of use compared to the assembled state and the cavity (7) extends sealingly between the mutually facing sealing surfaces (14). The invention further relates to a method for producing an electrical machine with a cooling jacket (1), the invention providing that a sealing element is arranged on at least one of the mutually facing sealing surfaces (14) before the inner part (3) is arranged in the outer part (4) (9) is applied and after arranging the inner part (3) and outer part (4) one inside the other at least the sealing element (9) is heated to at least one expansion temperature.

Description

The invention relates to a cooling jacket for an electrical machine, which consists of at least two parts which delimit a cavity which is channel-like designed for a cooling fluid, wherein the at least two parts have facing sealing surfaces, of which at least one for receiving an elastic sealing element serves.

Furthermore, the invention relates to a method for producing an electrical machine with a cooling jacket, wherein the stator and the rotor of the electric machine are arranged in an inner part of the cooling jacket and the inner part is disposed in an outer part of the cooling jacket, wherein delimited between the inner part and outer part of a cavity which is designed as a channel for a cooling fluid.

Such an electric machine is from the document DE 10 2007 060 654 A1 known. This shows a method for establishing a connection between the stator of the electric machine and a housing accommodating the stator. In order to achieve a high heat dissipation, the transfer of heat between the stator and the housing must be ensured. After joining the stator and the housing, clearance between the stator and the housing is present due to the clearance requirements necessary for production, which adversely affect the heat transfer between the winding conductors and the outer boundary surface. In order to improve the thermal conductivity between the stator and the housing, it is provided according to the publication that at least a partial surface of the common contact surfaces is coated with a polymer material having a irreversibly expanding at the first time reaching a certain expansion temperature material additive prior to connecting the stator and housing, and the connected stator-housing unit is heated to at least the expansion temperature.

It is still through the document EP 2 479 874 A1 an electric machine with a cooling jacket, in which the cavity between an inner part of the cooling jacket and an outer part of the cooling jacket is sealed by at least one arranged on an end face of the substantially cylindrical cooling jacket O-ring.

The publication DE 10 2009 031 727 A1 also describes an electric machine with a cooling jacket, in which, however, for sealing the cavity, the annular seals in grooves along the lateral surface of the cylindrical cooling jacket are inserted.

Higher power electrical machines are often equipped with suitable cooling systems. In particular, servomotors are also provided for use as travel drive of a motor vehicle with such cooling systems. The production-compatible implementation and production of such cooling systems is often associated with high costs. This results in corresponding costs. Therefore, efforts are being made to be able to produce suitable cooling systems for electrical machines with the lowest possible production costs.

In addition, it is of primary importance that the cooling systems of the electrical machines each have a high efficiency. This is often achieved by providing large heat conduction surfaces in the cooling channels of the cooling system in order to achieve an optimum cooling effect.

A highly effective cooling can be achieved in particular by liquid coolant. The coolants must be sufficiently tightly sealed in the respective cooling system. This is the only way to avoid the loss of coolant in the long run.

The above-mentioned problems have been solved so far that the seal between the end shields and the cooling jacket via a flat seal or by a liquid sealant. These sealing systems can cause problems at high pressures and temperatures. In addition, there is the risk in the arrangement of the seal on the lateral surface that the sealing profile is damaged during insertion of the inner part in the outer part or a sealant for applying a dosing required.

The object of the present invention is thus to propose a cooling jacket for an electrical machine and a method for producing an electrical machine with a cooling jacket, which have low production costs and in which the cooling jacket has a high efficiency.

This object is achieved with a cooling jacket for an electrical machine according to the features of claim 1. The dependent claims relate to particularly expedient developments of the invention.

According to the invention, therefore, a cooling jacket is provided in which a sealing element is arranged on one of the sealing surfaces, the extent of which in a direction of rotation of the electric machine Radial direction in an assembled state is less than the width of a gap between the facing sealing surfaces. In a condition of use, the sealing element is expanded relative to the mounting state and seals the cavity. The expansion of the sealing element after the assembly of the inner part and outer part of the cooling jacket into one another allows a simple and safe installation of the cooling jacket, wherein the cavity is not closed in the assembled state. Only by the expansion of the sealant, the cavity is closed and made the use state. In addition, it is possible by means of a radially expanding sealing element to compensate for both deformations and tolerances and mechanical stresses between the parts as well as to center the inner part and outer part to each other. Inner part and outer part of the cooling jacket are also referred to as inner jacket or outer jacket.

An electric machine equipped with such a cooling jacket can not only be an electric motor but also a generator. In addition, not only rotary drives, but also linear drives can be provided with the cooling jacket.

It has proved favorable that the sealing element is a preferably pasty coating mass or a preferably annular profile body. Although the application of a sealant requires a metering process, however, it is suitable for producing any desired spatial contours. As usual profile body so-called O-rings with a circular cross section are known. However, the profile body used according to the invention may also have other cross-sectional profiles. For example, the tread body is produced by mixing a carrier matrix, a silicone or a thermoplastic elastomer with an expansion additive and then forming it in a mold by injection molding or compression molding under a curing temperature.

It has proved favorable that the elastic sealing element consists of a carrier matrix and an expansion additive. The carrier matrix is a thermoplastic elastomer or a silicone, for example polydimethylsiloxane. The expansion additive expands irreversibly at or after first reaching a certain expansion temperature.

As a result, the expansion of the sealing element can be influenced in a targeted manner. The time of expansion of the sealing element is switchable or controllable.

In one embodiment of a sealing element provided as a profile body, a wire is provided in the sealing element. On the one hand, the wire serves to give the elastic sealing element a minimal dimensional stability. As an electrical resistance, however, the wire is also suitable for heating the sealing element. This can be used in particular to generate the required expansion temperature.

In the material composition of the sealing element, it has proved to be useful that the expansion additive corresponds to 5% to 10% by weight of the sealing element. This amount is sufficient to achieve the usually required expansion and not weaken the sealing element.

The expansion additive consists of gas-tight hollow microspheres in which a propellant is enclosed. The hollow microspheres expand irreversibly on reaching the expansion temperature by the evaporation or expansion of the blowing agent contained in the hollow microspheres. Even after cooling of the blowing agent, the hollow microspheres retain their extended shape. Under the increase in volume of the hollow microspheres, the elastic sealing element also expands. Since the hollow microspheres are irreversibly expanded, the sealing element also retains its extended shape. The sealing element has a closed-cell foam structure.

As an irreversibly expanding expansion additive, for example, the product "Expancel" type 950 DU 120 AKZO Nobel is suitable. "Expancel" is characterized by the fact that in a gas-tight, only a few microns large plastic cover a precisely measured amount of a propellant is included. When this microsphere is heated or heated, the plastic shell softens, the propellant becomes gaseous and the microsphere expands irreversibly in a defined manner. But there are also other material additives with similar properties conceivable, including those that work on other principles of action, such as expansion due to chemical processes.

The object is also achieved with a method for producing an electrical machine according to the features of claim 6. The subclaims relate to particularly expedient developments of the invention.

According to the invention, therefore, a method is provided, in which prior to arranging the inner part in the outer part of at least one of the facing sealing surfaces, a sealing element is applied and after arranging the inner part and outer part into each other at least the sealing element is heated to at least one expansion temperature. By heating the sealing element, this expands irreversibly at and / or after the first reaching a certain expansion temperature and seals the cavity. In this case, the sealing element connects the facing sealing surfaces of the inner part and outer part. The sealing element remains elastic even after reaching the expansion temperature.

According to a special embodiment of the sealing element, this connects adhesively with the two mutually facing sealing surfaces, so that not only the sealing element generates a fluid-impermeable space closure of the cavity, but also the inner part is held by means of the sealing element on the outer part.

To activate the expansion of the sealing element, it is advantageous that the sealing element, in particular an expansion additive in the sealing element begins to expand at a temperature of about 125 ° C and preferably reaches its maximum extent at a temperature of 170 ° C to 180 ° C. This ensures that at the usual process and ambient temperatures of the production and processing of the sealing element an expansion is avoided and the expansion can be initiated only at the desired time. When reaching the maximum extent, the sealing element is extended to up to 250% of its original cross-sectional size.

According to a further development of a sealing element provided as a liquid and / or pasty coating composition, it is designed in such a way that it cures when a curing temperature is reached and / or exceeded, ie it loses its liquid and / or pasty consistency and solidifies. However, the sealing element remains elastic. The curing temperature is lower than the expansion temperature. The curing temperature is 70 ° C to 100 ° C and makes it possible to cure the sealing element on the sealing surface without initiating its expansion.

An embodiment of the method according to the invention provides that first the stator of the electric machine is arranged in the inner part or connected thereto, then on each of the sealing surfaces of the inner part, a sealing element is applied, then the outer part and the inner part are brought together and positioned one inside the other and below the effect of heat is an expansion of the sealing element, wherein the cavity is sealed, and the inner part and outer part are centered in one another. This order is particularly necessary for electrical machines that require or have a permanent or detachable connection between the inner part and stator with great effort.

By using an elastic sealing element even after reaching an expansion temperature, it becomes possible to provide an alternative embodiment of the method according to the invention. In an alternative embodiment of the method according to the invention it is provided that first a sealing element is applied to each of the sealing surfaces of the inner part, then the outer part and the inner part are brought together, then under the influence of heat, an expansion of the sealing element takes place, wherein the cavity is sealed and the inner part and outer part are centered in one another and then the stator of the electric machine is arranged in the inner part or connected thereto. This makes it possible to make the assembly of the stator after a leak test of the cooling jacket and thus to reduce the committee. The connection of the stator to the inner part can be done non-positively, since the sealing element is elastic even after its expansion and can compensate for deformations of the cooling jacket as a result of a joining process.

The invention allows numerous embodiments. To further clarify its basic principle, some of them are shown in the drawing and will be described below. This shows in

1 a schematic representation of a section through an electric machine with a cooling jacket;

2 an enlarged schematic representation of a section of a sealing element for a cooling jacket of an electrical machine;

3 a schematic representation of an early operation of a first embodiment of a method for producing an electric machine with a cooling jacket;

4 a schematic representation of another step of in 3 shown first embodiment of a method;

5 a schematic representation of another step in the 3 and 4 shown first embodiment of a method;

6 a schematic representation of another step in the 3 to 5 shown first embodiment of a method;

7 a schematic representation of an early operation of a second embodiment of a method for producing an electric machine with a cooling jacket;

8th a schematic representation of another step of in 7 shown second embodiment of a method;

9 a schematic representation of another step in the 7 and 8th shown second embodiment of a method;

10 a schematic representation of another step in the 7 to 9 shown second embodiment of a method;

11 a schematic representation of another step in the 7 to 10 shown second embodiment of a method;

12 a schematic representation of another step in the 7 to 11 shown second embodiment of a method;

13 a schematic representation of a section of a sealing element for a cooling jacket of an electric machine in an assembled state, before its expansion;

14 a schematic representation of a section of a sealing element for a cooling jacket of an electric machine in a state of use, after its expansion.

1 shows a sectional view of a cooling jacket 1 an electric machine 2 , The cooling jacket 1 consists of a stator also called inner part 3 and an outdoor part 4 , The inner part 3 and a stator 5 the electric machine 2 are connected to each other immobile relative to each other. A rotor 6 the electric machine 2 is, however, about a rotation axis 8th rotatable to the stator 5 and to the cooling jacket 1 in the stator 5 arranged. The connection of Stator 5 and inner part 3 is usually non-positive and / or positive. One between inner part 3 and outer part 4 enclosed cavity 7 serves as a channel for a cooling fluid.

2 shows a sealing element 9 , which is used to seal the cavity 7 is provided. The sealing element 9 consists of an elastic carrier matrix 10 , which is preferably a silicone. Furthermore, the sealing element comprises 9 an expansion additive 11 which irreversibly expands at and / or after a first reaching a certain expansion temperature. The expansion supplement 11 again consists of gas-tight hollow microspheres 12 in which a propellant 13 is included. The hollow microspheres are irreversibly expanded when the expansion temperature is exceeded. The sealing element 9 is at one of the facing sealing surfaces 14 Of the parts 3 . 4 of the cooling jacket 1 arranged and stretches into one in the 4 and 8th shown gap 15 the facing sealing surfaces 14 out until the gap 15 from the sealing element 9 filled and thus the cavity 7 is sealed. The elasticity of the carrier matrix 10 and according to the sealing element 9 increase with increasing extent.

In the 3 to 12 are a cooling jacket according to the invention 1 and two different methods of making such a cooling jacket 1 shown. In both illustrated method for producing an electrical machine 2 with a cooling jacket 1 become the stator 5 and the rotor 6 in an inner part 3 of the cooling jacket 1 and the inner part 3 in an outdoor part 4 of the cooling jacket 1 arranged. Before placing the inner part 3 in the outer part 4 is at least one of the facing sealing surfaces 14 a sealing element 9 applied. After arranging the inner part 3 and outdoor part 4 into each other at least the sealing element 9 heated to at least one expansion temperature. The sealing element 9 expands irreversibly at and / or after the first reaching the expansion temperature, so filling the gap 15 and seals the cavity 7 from.

The 3 to 6 show a first embodiment of the inventive method for producing an electrical machine 2 , First, the stator 5 the electric machine 2 in the inner part 3 arranged or connected to this. Then at each of the sealing surfaces 14 of the inner part 3 a sealing element 9 applied. The sealing element shown here 9 is an annular profile body with a rectangular cross-section.

3 shows how after the application of the sealing elements 9 the outer part 4 and the inner part 3 be merged. The completed relative movement of the outer part 4 and inner part 3 is by two arrows 16 indicated.

4 shows that in the outer part 4 positioned inner part 3 , By heating the sealing elements 9 to the expansion temperature, here greater than 160 ° C, the sealing elements begin 9 to stretch 17 , The expansion 17 the sealing elements 9 takes place primarily in one related to the axis of rotation 8th radial direction, as indicated by an arrow.

5 shows the progression of expansion 17 the sealing elements 9 ,

6 shows the effect of expansion 17 the sealing elements 9 on the cooling jacket 1 , The gap 15 is closed and the cavity 7 thus sealed. The extended sealing element 9 exercises on both parts 3 . 4 of the cooling jacket 1 a compressive force 18 out, which is visualized by several arrows. Tolerance deviations and deformations of the parts 3 . 4 of the cooling jacket 1 are so balanced and there is a centering of the inner part 3 and outer part 4 , The cavity 7 can now be traversed by a cooling fluid.

The 7 to 12 show a second embodiment of the method according to the invention for producing an electrical machine 2 , First, at each of the sealing surfaces 14 of the inner part 3 a sealing element 9 applied. The sealing element shown here 9 is used as a liquid and / or pasty coating on the sealing surfaces 14 and then cured, for example, under the influence of a curing temperature or UV radiation. The sealing element remains 9 elastic.

7 shows how after the application of the sealing elements 9 the outer part 4 and the inner part 3 be merged. The completed relative movement of the outer part 4 and inner part 3 is by two arrows 16 indicated.

8th shows that in the outer part 4 positioned inner part 3 , By heating the sealing elements 9 to the expansion temperature, here greater than 160 ° C, the sealing elements begin 9 to stretch 17 , The expansion 17 the sealing elements 9 takes place primarily in a relative to the axis of rotation 8th radial direction, as indicated by an arrow.

9 shows the progression of expansion 17 the sealing elements 9 ,

10 shows the effect of expansion 17 the sealing elements 9 on the cooling jacket 1 , The gap 15 is closed and the cavity 7 thus sealed. The extended sealing element 9 exercises on both parts 3 . 4 of the cooling jacket 1 a compressive force 18 out, which is visualized by several arrows. Tolerance deviations and deformations of the parts 3 . 4 of the cooling jacket 1 will be balanced. The evenly distributed over the circumference compressive force 18 also causes a centering of the inner part 3 and outer part 4 , The cavity 7 can now be traversed by a cooling fluid, for example, for a leak test.

11 shows how the stator 5 after connecting the outer part 4 and inner part 3 in the inner part 3 is arranged. The completed relative movement of stator 5 and inner part 3 is by two arrows 16 indicated.

12 shows the inside part 3 arranged stator 5 , Force-locking the stator 5 the electric machine 2 in the inner part 3 associated with this. The resulting distortion is due to the elasticity of the flexible sealing element 9 balanced, without additional residual stresses in the cooling jacket 1 or the electric machine 2 be generated.

The 13 and 14 show the operation of the sealing element 9 the example of a designed as an annular shaped body with a circular cross-section sealing element 9 , 13 shows the sealing element 9 before the expansion. For production reasons, the space between the sealing surfaces 14 Of the parts 3 . 4 of the cooling jacket 1 Tolerances on. These tolerances can with a non-expanded sealing element 9 Undichtigkeitszonen 19 have as a consequence. 14 shows the sealing element 9 after the expansion. With the expansion has the sealing element 9 the leaks zones 19 filled in and the space between the sealing surfaces 14 Of the parts 3 . 4 of the cooling jacket 1 completely closed, leaving the cavity 7 is sealed.

LIST OF REFERENCE NUMBERS

1

cooling jacket

2

electric machine

3

inner part

4

outer part

5

stator

6

rotor

7

cavity

8th

axis of rotation

9

sealing element

10

support matrix

11

additional expansion

12

Hollow microsphere

13

propellant

14

sealing surface

15

gap

16

arrow

17

expansion

18

thrust

19

Undichtigkeitszone

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007060654 A1 [0003]
• EP 2479874 A1 [0004]
• DE 102009031727 A1 [0005]

Claims (9)

Cooling jacket ( 1 ) for an electric machine ( 2 ), which consists of at least two parts ( 3 . 4 ), which together form a cavity ( 7 ), which is designed as a channel for a cooling fluid, wherein the at least two parts ( 3 . 4 ) facing each other sealing surfaces ( 14 ) having a gap ( 15 ) and of which at least one of the sealing surfaces ( 14 ) for receiving an elastic sealing element ( 9 ) is provided, characterized in that on one of the sealing surfaces ( 14 ) a sealing element ( 9 ) is arranged, which in an assembled state in a to the axis of rotation ( 8th ) of the electric machine ( 2 ) radial direction has a smaller extent than a gap ( 15 ) between the mutually facing sealing surfaces ( 14 ), and which is extended in a use state with respect to the mounting state, wherein the cavity ( 7 ) is sealed. Cooling jacket ( 1 ) for an electric machine ( 2 ) according to claim 1, characterized in that the sealing element ( 9 ) is a preferably pasty coating material or a preferably annular profile body. Cooling jacket ( 1 ) for an electric machine ( 2 ) according to claims 1 or 2, characterized in that the sealing element ( 9 ) from a carrier matrix ( 10 ), for example a thermoplastic elastomer or a silicone, preferably of a polydimethylsiloxane, and an expansion additive ( 11 ) or several expansion additives ( 11 ), whereby the expansion additive ( 11 ) irreversibly expands during and / or after a first reaching a certain expansion temperature and / or for an irreversible volume increase of the sealing element ( 9 ). Cooling jacket ( 1 ) for an electric machine ( 2 ) according to at least one of the preceding claims, characterized in that the sealing element ( 9 ) from 5% to 10% of the weight fraction of the expansion additive ( 11 ) consists. Cooling jacket ( 1 ) for an electric machine ( 2 ) according to at least one of the preceding claims, characterized in that the at least one expansion additive ( 11 ) of gas-tight hollow microspheres ( 12 ) in which a propellant ( 13 ) or more propellants ( 13 ), wherein the hollow microspheres ( 12 ) of the propellant ( 13 ) are irreversibly extended when the expansion temperature is exceeded. Method for producing an electrical machine ( 2 ) with a cooling jacket ( 1 ), wherein the stator ( 5 ) and the rotor ( 6 ) of the electric machine ( 2 ) in an inner part ( 3 ) of the cooling jacket ( 1 ) and the inner part ( 3 ) in an outer part ( 4 ) of the cooling jacket ( 1 ), wherein between inner part ( 3 ) and outer part ( 4 ) a cavity ( 7 ), which is a channel for a cooling fluid, characterized in that prior to arranging the inner part ( 3 ) in the outer part ( 4 ) on at least one of the mutually facing sealing surfaces ( 14 ) a sealing element ( 9 ) is applied and after arranging the inner part ( 3 ) and outdoor part ( 4 ) in each other at least the sealing element ( 9 ) is heated to at least an expansion temperature. Method for producing an electrical machine ( 2 ) according to claim 6, characterized in that the sealing element ( 9 ), in particular an expansion supplement ( 11 ) in the sealing element ( 9 ), at a temperature above 125 ° C begins to expand and preferably reaches its maximum extent at a temperature of 170 ° C to 180 ° C, wherein the sealing element ( 9 ) is extended to up to 250% of the original cross-sectional size. Method for producing an electrical machine ( 2 ) according to claims 6 or 7, characterized in that first the stator ( 5 ) of the electric machine ( 2 ) in the inner part ( 3 ) is arranged or connected to it, then at each of the sealing surfaces ( 14 ) of the inner part ( 3 ) a sealing element ( 9 ) is applied, then the outer part ( 4 ) and the inner part ( 3 ) and then, under the influence of heat, an expansion of the sealing element ( 9 ), wherein the cavity ( 7 ) is sealed and inner part ( 3 ) and the outer part ( 4 ) are centered in each other. Method for producing an electrical machine ( 2 ) according to at least one of the preceding claims 6 to 8, characterized in that first on each of the sealing surfaces ( 14 ) of the inner part ( 3 ) a sealing element ( 9 ) is applied, then the outer part ( 4 ) and the inner part ( 3 ), then, under the influence of heat, an expansion of the sealing element ( 9 ), wherein the cavity ( 7 ) and the inner part ( 3 ) and outer part ( 4 ) are centered in one another and then the stator ( 5 ) of the electric machine ( 2 ) in the inner part ( 3 ) is arranged or connected to this.

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