Heat-generating element and electric heating device containing such

Abstract

A heat-generating element for an electric heating device includes a heating element casing which comprises a casing element formed from a ceramic material and a casing mating element formed from a ceramic material. The two casing elements bear against each other in a sealing manner and enclose, in a sealing manner between each other, a PTC element and conductor tracks. The conductor tracks bear, in an electrically conductive manner, against the PTC element and are assigned different polarities for energizing the PTC element. The heating element casing carries contact strips connected in an electrically conductive manner to the associated conductor tracks. At least one of the conductor tracks is formed by an electrically conductive element which is provided with through holes and which, in a height direction of the conductor track, comprises discrete points of support that bear against the PTC element and one of casing element and casing mating element. The present invention further relates to an electric heating device with at least one heater casing with a heat-generating element of the type described here that is arranged in a circulation chamber with a heating element casing joining at least one PTC element and contact strips energizing the PTC element as a structural unit. The heat generating element has the contact strips electrically connected to the PTC element projecting over itself. A partition wall separates the circulation chamber from a connection chamber of the heater casing. The contact strips of the PTC heating element protrude through the partition wall and are exposed and electrically connected.

Claims

1. A heat-generating element for a motor vehicle comprises: a heating element casing which comprises a casing element formed from a ceramic material and a casing mating element formed from a ceramic material, wherein the two casing elements bear against each other in a sealing manner and enclose, in a sealing manner between each other, a PTC element and conductor tracks, wherein the conductor tracks bear, in an electrically conductive manner, against the PTC element and are assigned different polarities for energizing the PTC element, wherein the heating element casing carries contact strips connected in an electrically conductive manner to the associated conductor tracks, and wherein at least one of the conductor tracks is formed by an electrically conductive element which is provided with through holes and which, in a height direction of the conductor track, comprises discrete points of support that bear against the PTC element and one of casing element and casing mating element.

2. The heat-generating element according to claim 1, wherein the electrically conductive element is a mesh, a knit fabric, or a fabric, each comprising or consisting of electrically conductive threads or fibers, or is an expanded metal.

3. The heat-generating element according to claim 1, wherein the through holes are filled with an adhesive mass.

4. The heat-generating element according to claim 1, wherein that at least one of the casing elements is formed to be shell-shaped.

5. The heat-generating element according to claim 1, wherein one of casing element and the casing mating element comprises a circumferential sealing groove, wherein the other of casing element and casing mating element comprises a sealing web engaging in the sealing groove, and wherein the sealing web is immersed in a sealing aid filled into the sealing groove.

6. The heat-generating element according to claim 1, wherein the conductor track and the associated contact strip are formed by a uniform electrically conductive element provided with through holes.

7. The heat-generating element according to claim 1, wherein one of the casing elements forms a flange through which the contact strips protrude.

8. The heat-generating element according to claim 1, wherein the projection surface of one of the main side surfaces of the PTC element onto the outer surfaces of the casing element runs plane-parallel to the main side surface of the PTC element.

9. The heat-generating element according to claim 1, wherein the electrically conductive element is a mesh, a knit fabric, or a fabric, each comprising or consisting of electrically conductive threads or fibers, or is expanded metal and that the through holes are filled with an adhesive mass.

10. The heat-generating element according to claim 1, wherein at least one of the casing elements is formed to be shell-shaped, and wherein one of casing element and casing mating element comprises a circumferential sealing groove, wherein the other of casing element and casing mating element comprises a sealing web engaging in the sealing groove, and wherein the sealing web is immersed in a sealing aid filled into the sealing groove.

11. The heat-generating element according to claim 10, wherein one of the casing elements forms a flange through which the contact strips protrude.

12. The heat-generating element according to claim 11, wherein the conductor track and the associated contact strip are formed by a uniform electrically conductive element that is provided with through holes.

13. An electric heating device comprising: at least one heater casing with a heat-generating element arranged in a circulation chamber, a heating element casing joining at least one PTC element and the PTC element and contact strips as a structural unit, wherein the contact strips are electrically connected to the PTC element projecting over itself, a partition wall separating the circulation chamber from a connection chamber of the heater casing in which the contact strips of the PTC heating element that protrude through the partition wall are exposed and electrically connected, and wherein the heat-generating element comprises a heating element casing which comprises a casing element formed from a ceramic material and a casing mating element formed from a ceramic material, wherein the two casing elements bear against each other in a sealing manner and enclose, in a sealing manner between each other, a PTC element and conductor tracks, wherein the conductor tracks bear, in an electrically conductive manner, against the PTC element and are assigned different polarities for energizing the PTC element, wherein the heating element casing carries contact strips connected in an electrically conductive manner to the associated conductor tracks, and wherein at least one of the conductor tracks is formed by an electrically conductive element which is provided with through holes and which, in a height direction of the conductor track, comprises discrete points of support that bear against the PTC element and one of casing element and casing mating element.

14. The electric heating device according to claim 13, wherein the heat-generating element is inserted into the partition wall in a sealing manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the present invention shall become apparent from the following description of an embodiment in combination with the drawing, in which:

(2) FIG. 1 shows a perspective explosion representation of an embodiment of the heat-generating element according to the invention

(3) FIG. 2 shows a sectional view of the embodiment shown in FIG. 1 and

(4) FIG. 3 shows a perspective partially cut-out representation of an electric heating device which receives several embodiments of the heat-witnessing element.

DETAILED DESCRIPTION

(5) FIG. 1 shows all the components of the embodiment of a heat-generating element which are prepared with a predetermined geometry and configuration for the creation of the heat-generating element.

(6) The heat-generating element in FIG. 2 marked with reference numeral 20 has a heating element casing 21 which is formed by a shell-shaped casing element 22 and a flat casing mating element 24 formed like a kind of cover. The shell-shaped casing element 22 has a base 26 (cf. FIG. 1) which is formed in a planar manner and with its outer surface 28 defines a heat-dissipating outer surface of the heating element casing which runs plane-parallel to the inner side of the base 26. A metal fabric marked with reference numeral 30 as an embodiment of an electrically conductive element provided with through holes is placed on this base 26. This metal fabric 30 as a uniform component forms a conductor track 32 and a planar and flat contact strip 34 associated with the conductor track 32. The conductor track 32 bears against the base 26 of the casing element 22. The conductor track 32 protrudes through a passage opening 36 which is recessed in a flange 38 of the casing element 22.

(7) Reference numeral 40 indicates a rectangular block-shaped PTC element whose main side surfaces 42, 44 are contacted by associated metal fabrics 30. A conductor track marked with reference numeral 46 is formed to be identical to the previously described conductor track 32, but placed inverted onto the PTC element 40, so that the latter's contact strip 34 is led out through the flange 38 in the longitudinal direction of the flange 38 offset relative to the other contact strip 34. The flange 38 forms a passage opening 48 also for this purpose. The corresponding arrangement of the contact strips 34 increases the air and creep distance between the two polarities which are associated with the conductor tracks 32, 46 inside and outside the heating element casing 22, 24.

(8) The shell-shaped casing element 22 has a circumferential sealing groove marked with reference numeral 50. As illustrated by the detail of the sectional representation according to FIG. 2, a sealing web 52 engages in this sealing groove 50. The sealing web 52 is immersed in permanently elastic adhesive 54, so that a circumferential seal of the interior of the heating element casing 42, 24 receiving the PTC element 40 and the conductor track 32 is created.

(9) The two casing elements 22, 24 are made of aluminum oxide. These are sintered parts produced in final contour.

(10) The two casing elements 22, 24 are evidently shaped in such a way that the outer surfaces 28, 56 formed by these casing elements 22, 24 comprise a projection surface to the main side surface 44 or 42 the PTC element 40, respectively, which is plane-parallel to these main side surfaces 42, 44. The heat dissipation from the heating element casing 22, 24 can be effected directly adjacent to the main side surface 42 or 44 to the PTC element. The heat dissipated from the main side surfaces 42, 44 of the PTC element 40 therefore in a direction perpendicular to the main side surfaces 42, 44 passes through only thin flat layers to reach the outer surface 56.

(11) The abutment segment 58 of the casing element 24 adapted to the contour of the flange 38 lies beyond a projection surface onto the PTC element 40. In other words, in a top view onto the outer surface 56 or 58, respectively, the PTC element 40 is located laterally next to the flange or the flange 38 or the abutment segment 58, respectively. For the production of the embodiment shown, the two casing elements 22,24 are first produced as sintered parts. First, the shell-shaped casing element 22 is provided with the metal fabric 30. Its contact strip 34 is passed through the passage opening 36. Before the placement onto the metal fabric 30, a predetermined amount of adhesive material is typically first applied over the surface onto the base 36 of the casing element 22. After the metal fabric 30 has been inserted into the casing element 22, the PTC element 40 is inserted. The PTC element is there pressed against the metal fabric 30, so that the discrete points of support formed by the metal fabric 30 are abutted against the surface of the PTC-element 40 in an electrically conductive manner. In a corresponding manner, the points of support are abutted directly against the base 26 in a heat-conductive manner. The adhesive is there displaced. It fills a gap between the circumferential surface of the PTC element 30 and the edge surrounding the base 24 and formed by the casing element 22.

(12) The adhesive is applied to the free upper side of the TPC element 40. Here as well, the application of the adhesive is effected as much over the surface as possible. The contact strip 34 of the further metal fabric 30 is subsequently inserted into the passage opening 48 provided for this. Also, the further conductor track 46 is for direct electrical contact of the PTC element at its main side surface 44 pressed against the same, thus displacing the adhesive. When applying the adhesive to the PTC element 40, the former can also be introduced into the sealing groove 50. The adhesive used within the heating element casing 22, 24 can be identical to the adhesive that connects the two casing elements 22, 24 to each other and seals them against each other. Introducing the adhesive between the metal fabric 30 and the two casing elements 22, 24 results in a firm connection between the casing elements 22, 24 and a holding function between them by introducing the adhesive into the sealing groove 50.

(13) The casing element 24 is finally mounted, whereby the sealing web 52 is introduced into the sealing groove 50. This results in circumferential sealing of the PTC element 40.

(14) Thereafter, pressure is applied typically from the outside against the outer surface 28 or 56, respectively, of the casing elements 22, 24 to ensure that the conductor tracks 32, 46 directly contact the associated inner surfaces of the casing elements 22, 24 and the main side surfaces 42, 44 of the PTC element 40 when the adhesive cures.

(15) Curing takes place under this external pressure at an increased temperature, so that the adhesive can cross-link faster. For this purpose, the heat-generating element can be electrified and thus heated.

(16) The accommodation of the embodiment of the heat-generating element discussed with reference to FIGS. 1 and 2 in an electric heating device of a motor vehicle is illustrated in FIG. 3.

(17) The electric heating device has a heater casing 1 made of plastic material and marked with reference numeral 1. The casing 1 forms inlet and outlet ports 2 which each define inlet or outlet openings 3, respectively, which lead to a circulation chamber 4 which is via a cover 5 separated in a fluid-tight manner from a connection chamber marked with reference numeral 6 and forms receptacles 7 which are formed as female plug elements of a fluid-tight plug connection which is effected by insertion of a sealing collar 8 into the receptacle 7. The sealing collar 8 is there formed circumferentially around the flange 38 and the abutment segment 58. The sealing collar 8 typically consists of a resiliently soft plastic material, in particular silicone. The sealing collar 8 can be formed by injection mold coating the heat-generating element 20. The flange 38 and the abutment segment 58 can have configurations formed in an adapted manner which lead to improved sealing and/or holding of the sealing collar 8 on the heat-generating element 20.

(18) In the position shown in FIG. 3, the contact strips 34 with their exposed ends protrude into the connecting chamber 6 and can there be electrically connected, as this is basically described in EP 3 334 244 A1. In the example presently shown, the cover 5 forms the partition wall which seals the circulation chamber 4 in a fluid-tight manner against the connection chamber 6 and forms the receptacles 7. In the embodiment shown, cover 5 is inserted as a separate component made of plastic material into the heater casing. Other configurations are also conceivable, in which, for example, a base of the heater casing 1 is formed as a separate cover element and the cover 5 together with the walls of the heater casing 1 defining the connecting chamber 6 or the circulation chamber 4, respectively, and extending substantially perpendicular to the base are formed integrally.