Electric heating device

Abstract

An electric heating device including a heater housing in which a partition separates a circulation chamber, through which a medium to be heated can flow, from a connection chamber in which electrical connections of a PTC heating element introduced into a recess of a heating rib projecting from the partition into the circulation chamber are exposed. The PTC heating element has at least one PTC element and strip conductors lying against it at both sides, of which at least one strip conductor is covered by an electrical insulation layer. To create an electric heating device which permits a delivery of heat of the PTC heating element to the environment in an improved way, the heating rib is formed by a heating rib frame which comprises at least one window in which the insulation layer is exposed.

Claims

1. An electric heating device, comprising: a heater housing in which a partition separates a circulation chamber, through which a medium to be heated can flow, from a connection chamber in which electrical connections of a PTC heating element are exposed, wherein the PTC heating element has at least one PTC element and strip conductors lying against opposed sides of the PTC element, wherein at least one of the strip conductors is covered by an electrical insulation layer, wherein the PTC heating element is introduced into a recess which is provided in a heating rib projecting from the partition into the circulation chamber, wherein the heating rib comprises a heating rib frame with at least one window in which the insulation layer is exposed to said medium, and wherein the heating rib frame of the heating rib is connected to the partition.

2. The electric heating device according to claim 1, wherein the electrical insulation layer sealingly abuts an inner side of the heating rib frame.

3. The electric heating device according to claim 1, wherein the electrical insulation layer is glued into the heating rib frame.

4. The electric heating device according to claim 1, wherein the heating rib frame forms two opposite windows in which one of the electrical insulation layers is respectively exposed, and wherein each strip conductor is respectively covered by an electrical insulation layer.

5. The electric heating device according to claim 1, wherein the heating rib frame comprises frame legs extending in parallel with the electrical insulation layer, against which the insulation layer lies circumferentially, and wherein a mass, by which the electrical insulation layer is sealed into the heating rib frame, is provided between the PTC heating element and inner walls of the recess.

6. The electric heating device according to claim 5, wherein a free space, which is provided between the insulation layers on the one hand and the PTC element and a front face of the heating rib frame provided opposite thereto on the other hand, is filled with the mass.

7. The electric heating device according to claim 5, wherein an upper free space, which is provided between the PTC element and the partition, is filled with the mass.

8. The electric heating device according to claim 5, wherein the mass surrounds the PTC element circumferentially.

9. The electric heating device according to claim 5, wherein the strip conductor is provided at a distance from the heating rib frame and is received on a front side in the mass.

10. The electric heating device according to claim 1, wherein the recess is U-shaped and opens for insertion of the PTC heating element towards the connection chamber, and wherein the circulation chamber is fitted to receive a liquid medium is sealed, and is provided with an inlet and an outlet nozzle for connection of the circulation chamber to a circuit for the liquid medium.

11. The electric heating device according to claim 10, wherein the heating rib is exposed over an entire circumference thereof in the circulation chamber.

12. The electric heating device according to claim 10, wherein the partition with the heating rib frame is made from a highly heat-resistance plastic.

13. The electric heating device according to claim 1, wherein the recess is U-shaped and opens for insertion of the PTC heating element towards the connection chamber, and wherein the circulation chamber is fitted to receive a liquid medium is sealed, and is provided with an inlet and an outlet nozzle for connection of the circulation chamber to a circuit for the liquid medium, wherein the heating rib is exposed over an entire circumference thereof in the circulation chamber.

14. The electric heating device according to claim 13, wherein the partition with the heating rib frame is made from a highly heat-resistance plastic.

15. An electric heating device, comprising: a heater housing in which a partition separates a circulation chamber, through which a medium to be heated can flow, from a connection chamber in which electrical connections of a PTC heating element are exposed, wherein the PTC heating element has at least one PTC element and strip conductors lying against opposed sides of the PTC element, wherein at least one of the strip conductors is covered by an electrical insulation layer, wherein the PTC heating element is introduced into a recess which is provided in a heating rib projecting from the partition into the circulation chamber, wherein the heating rib comprises a heating rib frame with at least one window in which the insulation layer is exposed to said medium, wherein the heating rib frame of the heating rib is connected to the partition, wherein the heating rib frame forms two opposite windows in which one of the electrical insulation layers is respectively exposed, and wherein each strip conductor is respectively covered by an electrical insulation layer.

16. The electric heating device according to claim 15, wherein the recess is U-shaped and opens for insertion of the PTC heating element towards the connection chamber, and wherein the circulation chamber is fitted to receive a liquid medium is sealed, and is provided with an inlet and an outlet nozzle for connection of the circulation chamber to a circuit for the liquid medium.

17. The electric heating device according to claim 16, wherein the heating rib is exposed over an entire circumference thereof in the circulation chamber and wherein the partition with the heating rib frame is made from a highly heat-resistance plastic.

18. An electric heating device, comprising: a heater housing in which a partition separates a circulation chamber, through which a medium to be heated can flow, from a connection chamber in which electrical connections of a PTC heating element are exposed, wherein the PTC heating element has at least one PTC element and strip conductors lying against opposed sides of the PTC element, wherein at least one of the strip conductors is covered by an electrical insulation layer, wherein the PTC heating element is introduced into a recess which is provided in a heating rib projecting from the partition into the circulation chamber, wherein the heating rib comprises a heating rib frame with at least one window in which the insulation layer is exposed to said medium, wherein the heating rib frame of the heating rib is connected to the partition, wherein the heating rib frame comprises frame legs extending in parallel with the electrical insulation layer, against which the insulation layer lies circumferentially, and wherein a mass, by which the electrical insulation layer is sealed into the heating rib frame, is provided between the PTC heating element and inner walls of the recess.

19. The electric heating device according to claim 18, wherein the mass surrounds the PTC element circumferentially.

20. The electric heating device according to claim 18, wherein the strip conductor is provided at a distance from the heating rib frame and is received on a front side in the mass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a perspective, partly cut, exploded view of an embodiment of an electric heating device;

(3) FIG. 2 is a perspective view of a heating rib with parts of a partition;

(4) FIG. 3 is a longitudinal sectional view through the heating rib according to FIGS. 1 and 2 along line IV-IV according to the illustration in FIG. 2;

(5) FIG. 4 is a longitudinal sectional view along line V-V according to the illustration in FIG. 2; and

(6) FIG. 5 shows the PTC heating element with adjoining electrical insulation layers of the embodiment.

DETAILED DESCRIPTION

(7) FIGS. 1 and 2 show parts of an electric heating device, as is e.g. known from EP 1 921 896 A1, the disclosure of which is herewith included in the content of the present application. The electric heating device has a tub-shaped housing base 2 which encloses a circulation chamber Z between a housing bottom 4, a partition 6 extending in parallel therewith and housing sidewalls 8 extending at a right angle thereto. Connection nozzles 10 project from opposite sidewalls 8 of the housing base 2 for connection of the electric heating device to a circuit for a liquid medium. Said connection nozzles 10 are sealingly connected to the housing sidewalls 8. The housing base 2 may be formed of plastic. The circulation chamber is made fluid-tight.

(8) The filling volume of the circulation chamber in water heaters of the above-described type is between 450 ml and 200 ml, preferably between 400 ml and 220 ml, and particularly preferably between 300 ml and 230 ml. This filling volume also comprises the filling volume of the nozzle. Each nozzle as such has a filling volume of about 7 ml. The illustrated embodiment is normally integrated in a cooling water circuit in a vehicle which has a volume of about 3 to 6 liters. At least one heat exchanger for heating air in the passenger compartment can be integrated into this cooling water circuit. In addition or alternatively, the cooling water circuit may also have heat exchanger surfaces for technical components of an electric vehicle to give these the necessary operating temperature in case of cold ambient temperatures.

(9) The partition 6 separates the previously mentioned circulation chamber Z from a connection chamber A, which serves the electrical connection of PTC heating elements 12 in the way to be described later. Heating ribs 14 project from the partition 6 into the circulation chamber Z. The heating ribs 14 extend at a right angle from the partition 6.

(10) FIGS. 2 to 4 illustrate details of these heating ribs 14.

(11) The heating ribs 14 have a heating rib frame 16 which is connected to the partition 6. The heating rib frame 16 is made from a high temperature-resistant material of a preferably good thermal conductivity, e.g. metal, particularly sheet metal, or however plastic. A thermoplastic is to be preferred to which thermally conductive particles have been added to enhance the thermal conductivity. The heating rib frame 16 is connected to the partition 6. The partition 6 and thus the housing base 2 may be made of plastic. This is also applicable to a housing top marked with reference numeral 18 in FIG. 1, which covers the connection chamber A at the top side as a housing cover. Thus the illustrated embodiment of an electric heating device can be produced at low costs and simply predominantly by the injection molding of plastics.

(12) The heating rib frame 16 has a respective window 22 at two opposite main side surfaces 20. Each window is confined by four frame legs 24, each extending at a right angle to one another. The frame legs 24 are integrally formed on the heating rib frame 16 and extend in parallel with the main opening of the window 22. An insulation layer 26 which is here formed by an aluminum oxide plate is visible in the window 22.

(13) As illustrated by FIGS. 3 and 4, two insulation layers 26 adjoin the outside of the FTC heating element 12 which in the present case comprises a single PTC element 30 and contact sheets 32 adjoining the same at both sides, which form strip conductors within the meaning of the present invention. The contact sheets 32 are cut free at the end side and form connecting lugs 34 integrally formed on the contact sheets 32 for the electrical connection of the FTC heating element 28. The contact sheets 32 are glued to the PTC element 30. As can further be seen in FIGS. 4 and 5, the contact sheets 32 project, just with their connecting lugs 34, over the FTC element 30 circumferentially. Otherwise, the contact sheets 32 end flush with the outer circumferential surface of the PTC element 30. By contrast, the insulation layers 26 project over the FTC element 30 on all sides.

(14) The heating rib frame 16 is fitted for the accommodation of the embodiment of the PTC heating element 12 as shown in FIG. 5. For instance, a U-shaped recess 38 of the heating rib frame 16 which opens towards the connection chamber A via an insertion opening 36 recessed in the partition 6 is dimensioned such that the insulation layers 26 just fit into the recess 38. The insulation layers 26 thereby serve as spacers to keep the PTC element 30 and the contact sheets 32, which are adhesively bonded thereto, at a distance from the front faces 40 which are formed by the heating rib frame 16 and interconnect main sidewalls in which the windows 22 and the insulation layers 26 are located.

(15) Normally, the housing parts 2, 18 are first U-shaped, for instance by plastic injection molding. The heating rib frame 26 can here be connected to the housing base 2 by overmolding. The housing bottom is here normally produced as a separate component and subsequently connected to the housing sidewalls 8. The FTC heating elements are afterwards introduced with the insulation layers 26, previously glued thereto, as an intermediate product into the U-shaped recess 38. With this way of positioning, free spaces 48 are obtained between the FTC element 30 and the front faces 40 both on the side edges, marked with reference numeral 44, of the heating rib frame 16 and on sides of a bottom 46 of the heating rib frame 16. The free spaces 48 form a U-shaped continuum which communicates with an upper free space 50, which is partly penetrated by the connecting lugs 34. A mass of good thermal conductivity which is electrically insulating is now filled in through the insertion opening 36. The free spaces 48, 50 are thereby filled. The PTC element 30 is now coupled in a heat-conducting manner also to the respectively opposite front faces 40 of the heating rib frame 16. Casting mass is filled in to such an extent that it is at about the same level as the upper edges of the insulation layer 26. This state is illustrated in FIGS. 2 and 4, the casting mass being marked with reference numeral 52. Thus, all creep distances and air gaps between the contact sheets 32 of different polarity are filled by said mass 52. The PTC heating element is thereby received in a highly insulating manner in the heating rib 14. The insulation layers 26 extend almost up to the front faces 40 and enclose the casting mass 52 thereinbetween. The casting mass cross-links at ambient temperature and sets accordingly. The cross-linking of the two-component mass 52 can be accelerated by powering and thereby heating the PTC heating element 12 during production.

(16) As is particularly illustrated in FIGS. 2 and 3, the heating rib 14 is exposed over the whole circumference in the circulation chamber. It goes without saying that the heating rib 14 is the part that projects from the partition 6. Thus, the one side surface of the heating rib 14 lies in the circulation chamber against the partition 6 also in the case of a fully circumferential exposure in the sense of the present invention. The electrical insulation layer 26 sealingly abuts an inner side of the heating rib frame 16. Thus the electrical insulation layer 26 closes the window 22 at the inner side of the heating rib frame 16.