Connection element for electrically connecting a fluid-coolable individual line, fluid-coolable individual line unit, and charging cable

Abstract

The invention relates to a connection element for electrically connecting an individual line which has a concentric conductor arrangement (32) and a central passage (33) for a cooling fluid. The connection element comprises an electrically conductive housing (2) with a sleeve-shaped pressing portion which is suitable for producing a press connection to the concentric conductor arrangement (32). The electrically conductive housing (2) here has an internal cooling passage (10) with a connection opening (11) for an external cooling line, said cooling passage leading into a space surrounded by the sleeve-shaped pressing portion. In addition, the connection element comprises a counterpressure element (3) which can at least partially lie in the space surrounded by the sleeve-shaped pressing portion. The counterpressure element (3) is furthermore configured to support the concentric conductor arrangement (32) on the inner side thereof when the sleeve-shaped pressing portion is compressed during the production of a press connection. The invention furthermore relates to a fluid-coolable individual line unit and to a charging cable having a charging connector.

Claims

1. A fluid-coolable individual line unit for a charging cable, comprising a first connection element, said first connection element including: an electrically conductive housing, a sleeve-shaped compression section, the electrically conductive housing having an internal cooling channel with a connection opening for an external cooling line, said cooling channel leading into a space surrounded by the sleeve-shaped compression section, the connection element furthermore comprising a counterpressure element, which can lie at least partially in the space surrounded by the sleeve-shaped compression section, an individual line having a first and a second end, the individual line comprising: a concentric conductor arrangement, at least one central channel for a cooling fluid, which is enclosed by the conductor arrangement, and an insulation directly enclosing the conductor arrangement, said insulation being impenetrable and electrically insulating for the cooling fluid, and a first stripped end piece at the first end of the individual line, on which the insulation is axially set back with respect to the conductor arrangement, wherein an inner circumferential surface of the compression section of the first connection element is in a radial compression joint with the conductor arrangement on the stripped end piece, as a result of which an electrical connection between the connection element and the concentric conductor arrangement is established, wherein the counterpressure element is arranged in the central channel of the individual line so that it lies at least partially in the space surrounded by the sleeve-shaped compression section, and supports the concentric conductor arrangement on the inside thereof and, at the same time, is in a compression joint with the concentric conductor arrangement, said counterpressure element permitting a fluid connection through the central channel of the individual line between the internal cooling channel of the first connection element and the second end of the individual line, wherein the individual line comprises a support structure in the form of a helix, which is arranged in the central channel and has a longitudinal extent which is directly enclosed by the conductor arrangement, said helical support structure being arranged along said counterpressure element and between the counterpressure element and the sleeve-shaped compression section, and wherein a sealing means in the form of a flexible hose is partially arranged on the sleeve-shaped compression section and partially on the insulation in the area of the first end of the individual line to create a fluid-tight connection between the sleeve-shaped section and the insulation.

2. The fluid-coolable individual line unit as claimed in claim 1, wherein the conductor arrangement can be penetrated by the cooling fluid in the central channel.

3. The fluid-coolable individual line unit as claimed in claim 1, the flexible hose being a shrink-on hose.

4. The fluid-coolable individual line unit as claimed in claim 1, wherein a second connection element is arranged at the second end of the individual line, wherein the second connection element comprises means for the electrical connection of the individual line to an electric charging station, and wherein the means for electrical connection is provided for connecting the fluid-coolable individual line to a power connection or to a terminal or plug system of the electric charging station.

5. A charging cable having a charging plug connector, comprising a first and a second fluid-coolable individual line unit as claimed in claim 1, and a common protective sheath, wherein the charging plug connector comprises a charging plug housing.

6. The charging cable as claimed in claim 5, wherein the charging cable comprises at least one hose made of a fluidtight material surrounded by the common protective sheath and connected to at least one of the external cooling connections of the two first connection elements, wherein a cooling fluid passed through one of the central channels of the two fluid-coolable individual line units can be returned in the opposite direction through the at least one hose.

7. A connection element for electrically connecting an individual line which has a concentric conductor arrangement and a central channel for a cooling fluid, the connection element comprising: an electrically conductive housing, having a sleeve-shaped compression section which is suitable for producing a compression joint with the concentric conductor arrangement, wherein the electrically conductive housing has an internal cooling channel having a connection opening for an external cooling line, said cooling channel leading into a space surrounded by the sleeve-shaped compression section, wherein the connection element furthermore comprises a counterpressure element, which can lie at least partially in the space surrounded by the sleeve-shaped compression section, wherein the counterpressure element is furthermore configured to support a concentric conductor arrangement on the inner side thereof when the sleeve-shaped compression section is compressed during the production of a compression joint, and is designed to be fluid-permeable in the pressed state in order to ensure a fluid connection through the counterpressure element, wherein the counterpressure element is dimensioned such that a helical support structure of the individual line may be arranged along said counterpressure element and between the counterpressure element and the sleeve-shaped compression section, and wherein the connection element comprises a sealing means in the form of a flexible hose which may be arranged partially on the sleeve-shaped compression section and an insulation of the individual line.

8. The connection element as claimed in claim 7, wherein the counterpressure element substantially has a cylindrical outer contour.

9. The connection element as claimed in claim 8, wherein the counterpressure element is hollow-cylindrical and ensures fluid connection through a central through-opening.

10. The connection element as claimed in claim 8, wherein the counterpressure element is arranged on the housing.

11. The connection element as claimed in claim 10, wherein the counterpressure element is formed in one piece or as a single part with the housing.

12. The connection element as claimed in claim 7, wherein the counterpressure element has a profile on its outer casing, which profile permits a positive connection to the conductor arrangement during the production of the compression joint.

13. The connection element as claimed in claim 7, wherein the housing of the connection element is produced from copper or a copper-containing alloy.

14. The connection element as claimed in claim 7, wherein the connection element comprises a contact part, wherein the contact part has a female socket which is suitable for use in a DC charging plug connector for an electric vehicle.

15. The connection element as claimed in claim 14, wherein the contact part is coated with a wear-resistant, electrically highly conductive coating, wherein the coating is, in particular, a silver, gold or nickel platinum coating.

16. The connection element as claimed in claim 15, wherein the conductive contact part is detachably connected to the housing of the connection element.

17. The connection element as claimed in claim 15, wherein the conductive contact part can be connected to the housing by means of a screw connection, wherein the housing of the connecting element preferably has an internal thread, which can be screwed to an external thread of the contact part.

18. The connection element as claimed in claim 7, wherein the internal cooling channel opens axially into the space surrounded by the sleeve-shaped compression section.

19. The connection element as claimed in claim 7, wherein the connection opening is arranged perpendicularly to a connection direction of the individual line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings used to explain the exemplary embodiment:

(2) FIG. 1a shows a perspective view of a connection element having a contact part and a separate counterpressure element;

(3) FIG. 1b shows a sectional view of the housing of the connection element according to FIG. 1a;

(4) FIG. 1c shows a sectional view of the counterpressure element according to FIG. 1a;

(5) FIG. 1d shows a sectional view of the contact part according to FIG. 1a;

(6) FIG. 2a shows a detail of an axial section of a first embodiment of the inventive fluid-coolable individual line unit, which comprises a connection element according to FIGS. 1a-1d;

(7) FIG. 2b shows a cross section through the individual line of the fluid-coolable individual line unit according to FIG. 2b;

(8) FIG. 2c shows the distribution of the cooling fluid in the individual line of FIG. 2b;

(9) FIG. 3 shows a detail of an axial section of a second embodiment of the inventive fluid-coolable individual line unit;

(10) FIG. 4 shows a detail of an axial section of a third embodiment of the inventive fluid-coolable individual line unit;

(11) FIG. 5 shows an oblique view of a charging plug connector of an inventive DC charging cable;

(12) FIG. 6 shows a cross section through a charging cable having two individual lines, a neutral conductor, eight signal lines, and two hoses, and

(13) FIG. 7 shows a schematic illustration of a DC charging cable having two fluid-coolable individual line units and a charging plug connector.

(14) In principle, identical parts are provided in the figures with the same reference signs.

WAYS OF CARRYING OUT THE INVENTION

(15) FIGS. 1a-d show a first embodiment of the inventive connection element 1 for connecting an individual line having a concentric conductor arrangement and a central channel for a cooling fluid. The connection element 1 comprises an electrically conductive housing 2, a counterpressure element 3 and a contact part 4. FIG. 1a shows a perspective illustration of the various non-assembled individual components. The individual parts of the connection element are each shown in axial section in FIGS. 1b-1d: the electrically conductive housing 2 is shown in FIG. 1b, the counterpressure element in FIG. 1c and the contact part in FIG. 1d.

(16) The electrically conductive housing 2 has a substantially cylindrical shape and is preferably produced from copper or a copper alloy. As an axial extension of a main section 5, it comprises a sleeve-shaped compression section 6. In the context of this application, this sleeve-shaped compression section is also referred to as a compression sleeve. This has a substantially constant wall thickness, for example a 2.5 mm wall thickness, before pressing. Only toward the open end is the wall thickness of the compression section tapered outwards at its inner circumferential surface 7, thereby simplifying the introduction of the concentric conductor arrangement of the individual line to be connected. In addition, owing to the larger inside diameter in this region, it is possible to partially accommodate the insulation of the individual conductor to be connected, thereby simplifying the sealing of the individual line from the outside. FIGS. 1a and 1b show the shape of the housing 2 after pressing. Therefore, the press indentations 8a and 8b (shown in greatly simplified form) on the outer circumferential surface 9 of the compression section are also shown, these being produced by the pressing operation in two different axial positions. The total of six press indentations 8a arranged radially on the outer circumferential surface 9 result from a first pressing operation with a two-part hexagonal pressing tool, and the six further press indentations 8b arranged radially on the outer circumferential surface 9 result from a second pressing operation. Only three of the total of six press indentations 8a, 8b are visible in FIG. 1a. The electrical housing 2 comprises an internal cooling channel 10 having a connection opening 11 arranged radially in the main section 5 of the cylindrical housing 6. The connection opening 11 is thus arranged perpendicularly to the compression sleeve axis or to the connection direction of the individual line. The internal cooling channel 10 opens axially and centrally into the space 12 surrounded by the sleeve-shaped compression section 6. The connection opening 11 has an internal thread 13, on which a hose connection element can be mounted or screwed.

(17) The counterpressure element 3 has a substantially hollow-cylindrical shape. It is produced from a threaded pin made of stainless steel. The inside diameter of the central through-opening 14 of the counter-pressure element 3 is, for example, approximately 5 mm and the wall thickness of the hollow cylinder is, for example, approximately 2 mm. The dimensions must be selected in such a way that sufficient pressure resistance is ensured during pressing and the central through-opening is kept open even after pressing. On the outer circumferential surface 15, the counterpressure element has a structure which is formed by a helically formed groove 16 in the outer circumferential surface 15. At the front end, the outer circumferential surface 15 of the counterpressure element 3 has a chamfer 17, which simplifies the introduction of the counterpressure element 3 into the concentric conductor arrangement of the individual line.

(18) The contact part 4 is produced from a copper-containing alloy. However, it can also be produced from other electrically highly conductive materials, in particular from electrically highly conductive alloys. The contact part of this exemplary embodiment is silver-coated. However, other wear-resistant, highly conductive compounds, such as gold and nickel-platinum coatings, are also suitable. The contact part forms a female socket 20 for mating with a pin-shaped contact. At the end opposite the socket 20, the contact part comprises a threaded bolt with an external thread 21. This is provided for screwing to the main section 5 of the housing 2. For this purpose, the main section comprises a blind hole 18 with an internal thread 22 on the side facing away from the compression section 6. For securing the screw connection, a spring ring (not shown) is used as screw locking device between the housing 2 and the contact part 4. A square profile 23 arranged on the contact part makes it possible to screw on the contact part 4 with a double open-end wrench. In order to prevent rotation of the housing 2 in a plug connector housing (not shown in FIG. 1a), the housing 2 has a hexagonal profile, which can be paired with a corresponding hexagonal recess in the plug connector housing.

(19) FIGS. 2a-c show a first embodiment of the inventive fluid-coolable individual line unit 30. FIG. 2a shows a detail of fluid-coolable individual line unit 30. This embodiment of the fluid-coolable individual line unit 30 comprises a connection element 1 of the kind shown in FIGS. 1a-1d, as well as an individual line 31 having a concentric conductor arrangement 32 and a central channel 33.

(20) However, FIG. 2a does not show the contact part 4 of the connection element 1 but only the components which are directly required for the connection of the individual line, namely the electrically conductive housing 2 with the sleeve-shaped compression section 6 and the counterpressure element 3. The partial view 2a furthermore shows a stripped end of the fluid-coolable individual line 31 in longitudinal section.

(21) FIG. 2b schematically shows a cross section of the individual line 31 for a region in which the individual line 31 is not stripped of insulation. In FIG. 2b, the region in which the conductor arrangement 32 is arranged has a gray background. It comprises a conductor braid 34 (only visible in FIGS. 2b and 2c but not in FIG. 2a) and stranded conductors 35 (likewise only visible in FIGS. 2b and 2c, not in FIG. 2a) arranged on the conductor braid 34. In the central channel 33, which is enclosed by the conductor arrangement or by the conductor braid 34, a helix 36 is arranged as a support structure, wherein the conductor braid 34 directly encloses the helix 36 in this case. The stranded conductors 35 rest on the conductor braid 34. The conductor braid 34 and the stranded conductors 35 are in electric contact with one another and jointly conduct the current which flows through the individual line 31. The stranded conductors 35 are directly enclosed by insulation 37. The central channel 33, in which the helix 36 is also located, is bounded by the conductor braid 34.

(22) However, this boundary is not sealed against cooling fluid, and therefore the cooling fluid 38 can spread in the radial direction as far as the insulation 37. FIG. 2c shows the distribution of the cooling fluid 38 in the individual line 31. The cooling fluid 38 is shown in gray. Starting from the channel 33, it is distributed through the conductor braid 34 between the stranded conductors 35 as far as the insulation 37. The insulation 37 is fluidtight. The conductor braid 34 consists of many conductor wires and leaves free spaces between at least some of these conductors. The stranded conductors 35 themselves are as a rule fluid-impermeable, but the fluid is distributed in the free spaces. Finally, it achieves the distribution shown, in which substantially all the stranded conductors 35 are in contact with the fluid over a large part of their surface and thus very good cooling is achieved.

(23) As can be seen from FIG. 2a, the insulation 37 is set back with respect to the conductor arrangement 32 at the stripped end 39 of the individual line. In the region of this stripped end 39, the counterpressure element 3 is arranged within the central channel 33. The stripped section 39 of the conductor arrangement 32 is arranged in the space 12 surrounded by the sleeve-shaped compression section 6 (see FIG. 1a). In this case, the counterpressure element 3 is arranged in the central channel 33 in such a way that it lies for the most part in the space 12 surrounded by the sleeve-shaped compression section 6. At the same time, the counterpressure element 3 supports the concentric conductor arrangement 32 on its inner side 40 in the axial region in which the conductor arrangement 32 is in a compression joint with the compression section 6. In this exemplary embodiment, the inner side 40 of the concentric conductor arrangement 32 is formed by the inner circumferential surface of the conductor braid 34, which is illustrated in FIGS. 2b and 2c but not in FIG. 2a. Said axial region is the region in which pressing of the compression sleeve section 6 with the concentric conductor arrangement 32 has been carried out by two pressing operations in different positions offset axially with respect to one another. The axial press indentations 8a, 8b are shown schematically in FIG. 2a. When the counterpressure element 3 was introduced, the helix 36 was compressed in the direction of the opposite end (not shown) of the individual line in such a way that the helix 36 lies between the counterpressure element 3 and the opposite end of the individual line 31.

(24) In FIG. 2a, a possible flow direction of the cooling fluid is shown by means of arrows 41-43. In the illustrated case, the cooling fluid flows from the individual line end (not shown) opposite the connection element 1, through the central channel 33 of the individual line 31 and through the through-opening 14 of the counterpressure element into the internal cooling channel 10 of the connection element and from there to the connection opening 11. Although the conductor arrangement 32 is compressed in the stripped region 39 by the pressing action, the conductor arrangement 32 can still have fluid permeability there, depending on the degree of compression. Likewise, there is no appreciable compression directly at the outer edge of the compression section. Liquid could therefore escape to the outside between the insulation 37 and the compression section 6 without any countermeasure. Depending on the degree of compression, a small amount of liquid can also flow past the counterpressure element 3 through the conductor arrangement 32, as indicated by the arrow 44. The sealing hose 45 serves as a sealing means in order to prevent an unwanted escape of the cooling fluid 38 through the gap between the insulation and the compression section 6. A shrink-on hose is particularly suitable as sealing hose 45. In addition to the sealing hose, a sealing adhesive tape and silicone are advantageously used for sealing. However, it would also be possible to use other sealing means, such as a sealing ring or a hose fastened with clamps. The flow direction indicated by the arrows 41-44 can of course also be reversed.

(25) FIG. 3 shows a second embodiment of the inventive fluid-coolable individual line unit 50. It shows a detail of an axial section through the fluid-coolable individual line unit 50. This embodiment largely corresponds to the first embodiment of the individual line unit 30. In contrast to the first embodiment, in this embodiment the counterpressure element 53 is formed in one piece with the electrically conductive housing 52. It is also possible to provide a separate counterpressure element 53 and to arrange it on the housing 52. A separate counterpressure element makes it possible to use another material, in particular a material with a higher strength and/or stiffness. This makes it possible, for example, to select the diameter of the through-opening of the counterpressure element to be larger and thus to achieve a higher flow rate.

(26) FIG. 4 is a schematic partial view of an axial section through a third embodiment of the inventive fluid-coolable individual line unit 60. This embodiment largely corresponds to the first embodiment of the fluid-coolable individual line unit 30. In contrast to the first embodiment, in this embodiment the helix 66 surrounds the counterpressure element 63. The counterpressure element is thus designed in such a way that it can be pushed into the central channel parallel to the open support structure. In the case of the helix 66 and the hollow-cylindrical counterpressure element 63, the outer diameter of the counterpressure element is thus selected in such a way that it can be pushed into the helix. In this case, too, the counterpressure element can be formed in one piece with the housing 62, and it is also possible in this case to arrange the separate counterpressure element 63 on the housing 62.

(27) FIGS. 5-7 show various views of a DC charging cable.

(28) FIG. 5 illustrates the charging plug connector 70 in an oblique view. It comprises an IEC 62196-3 standardized charging plug housing 71, only half of which is illustrated here. The charging plug connector 70 has a first and a second DC plug contact 72, 72′, which are in each case formed by contact parts of the inventive connection elements and are connected by these to fluid-cooled individual lines. In this example, only the first individual line 73 with a first connection element 74 is shown. The cooling liquid is returned by means of the cooling hose 75, which is connected to the connection opening of the connection element 74 via a fluid connection piece 76. The charging plug connector also comprises a neutral conductor pin 77 and two a first and a second signal pin 78, 78′.

(29) A cross section through the DC charging cable 80 is shown in FIG. 6. This comprises the first and a second individual line 73, 73′, the neutral conductor 81, eight signal lines, which are each combined in pairs in the four sheaths 82, and two cooling hoses 75, 75′. The cooling hoses are made of a flexible, heat-resistant and fluidtight material and have a round cross section. Depending on the application and above all on the cooling fluid used, polyurethane, polyethylene, silicone, polyvinyl and polyamide are suitable, for example. The signal lines are shielded by an aluminum/polyester tape. However, it is also possible to use other shielding tapes. The neutral conductor 81 is constructed as a shielding braid and encloses all the abovementioned lines and hoses: the individual lines 73, 73′, the sheaths 82 with the signal lines, and the cooling hoses 75, 75′. All of this is surrounded by a common protective jacket 85. It combines individual lines 73, 73′, the neutral conductor 81 and the signal lines within a common protective jacket 85 and connects the charging plug connector 70 to the charging station. The protective jacket 85 has the shape of a round hollow cylinder with an inside diameter which results from twice a single line diameter and twice the thickness of the shielding braid of the neutral conductor 81. The first and second individual lines 73, 73′ both have a round cross section and the same diameter. The first individual line 73 uses a helix 86 and the second individual line 73′ an open star-shaped profile 87 as a support structure. The different support structures are shown here only to illustrate the possible use of different support structures. Advantageously, however, both individual lines have the same support structure. Both individual lines have a conductor arrangement 88, 88′ which comprises two conductor braid layers arranged concentrically to one another.

(30) The first and the second individual line 73, 73′ are arranged adjacent to one another and touch one another. The two cooling hoses 75, 75′, which return the cooling fluid of the individual lines 73, 73′, are each arranged in such a way that they are in contact with one of the individual lines 73 and 73′ and the neutral conductor 81. This results in a compact arrangement of all components of the DC charging cable 80 and of the two individual lines 73, 73′. In addition, there are eight contact points in this arrangement which support the insulation 85.

(31) At an outside diameter of 31 mm, the DC charging cable has a conductor cross section of 35 mm.sup.2 and is designed to be able to transmit a continuous DC current of 700 A over 7 m without the surface temperature of the DC charging cable becoming hotter than 50° when cooled with water at a temperature of 20° C. and a flow rate of 1.81/min.

(32) FIG. 7 shows schematically the charging cable connected to a DC charging station 91 according to the exemplary embodiment shown in FIGS. 5 and 6. In the greatly simplified illustration, the signal lines and the neutral conductor as well as the pins are not shown. Two of the eight signal lines are connected to the signal pins 78 (FIG. 5). The remaining signal lines can be used, inter alia, for moisture and temperature sensors in the charging plug.

(33) The two individual lines 73, 73′ each comprise a first connection element 74, 74′ and a second connection element 89, 89′ at their two ends. The first connection elements 74, 74′ are arranged in the charging plug housing 71. Both connection elements each have a contact part 95, 95′ with a female socket. The cooling fluid cooled down by the DC charging station is supplied to both connection elements via the central channel of the respective individual line 73, 73′. The return takes place via the cooling hose 75, 75′ connected in each case to the connection opening of the first connection element 74, 74′. The individual lines 73, 73′ are each connected to the DC charging station 91 via a second connection element 89, 89′. The cooled cooling fluid is in each case supplied to the central channel of the respective individual line 73, 73′ via a fluid outlet line 93, 93′ and the respective connection opening of the second connection element 89, 89′. In this exemplary embodiment, the connection opening is embodied axially or parallel to the compression section of the respective second connection element 89, 89′. The second connection element 89, 89′ in each case has a means for the electrical connection of the respective individual line 73, 73′ to one of the two power connections 94, 94′ of the electric charging station, for example to a busbar.

(34) In summary, it may be stated that a connection element has been provided which makes possible a mechanically robust and at the same time inexpensive connection to a fluid-cooled conductor which has a central fluid channel surrounded by a concentric conductor. The connection elements are suitable both for the connection of the charging connector to the individual lines and for the connection of the individual lines to a charging station. As a result, fluid-coolable DC charging cables become more robust and at the same time less expensive.