Abstract
An electric heating includes a housing having a partition wall which separates a connection chamber from a heating chamber for dissipating heat and from which at least one receiving pocket, protruding into the heating chamber as a heating rib, preferably tapering towards its lower and closed end, protrudes. A PTC heating element, including at least one PTC element and conductor tracks for energizing the PTC element with different polarities, is accomodated in the housing with the coductor tracks being electrically conductively connected to the PTC heating element and being are electrically connected in the connection chamber. A pressure element is received in the housing and holds heat extraction surfaces of the PTC element abutted against oppositely disposed inner surfaces of the receiving pocket. To reduce mechanical stress on the PTC element or an insulating layer and, while at the same time retaining the PTC heating element in the receiving pocket, at least one web acts in a positive-fit and/or force-fit manner on the pressure element.
Claims
1. An electric heating device comprising: a housing having a partition wall which separates a connection chamber from a heating chamber for dissipating heat and from which at least one receiving pocket, protruding into the heating chamber as a heating rib protrudes, a PTC heating element accommodated in the housing, the PTC heating element including at least one PTC element and conductor tracks for energizing the PTC element with different polarities, the conductor tracks being electrically conductively connected to the PTC element and being electrically connected in the connection chamber; and a pressure element accommodated in the housing, wherein the pressure element holds heat extraction surfaces of the PTC element abutted against oppositely disposed inner surfaces of the receiving pocket; and at least one web which acts in at least one of a positive-fit or a force-fit manner on the pressure element for retaining the PTC heating element in the receiving pocket.
2. The electric heating device according to claim 1, wherein the web acts in a positive-fit and a force-fit manner on the pressure element.
3. The electric heating device according to claim 1, wherein the web is provided in at least one of the receiving pocket and in the connection chamber.
4. The electric heating device according to claim 4, wherein the web is provided in the connection chamber.
5. The electric heating device according to claim 4, wherein the web is provided in the receiving pocket.
6. The electric heating device according to claim 1, wherein a web provided in the connection chamber and interacts with at least one of a free end of the pressure element, the PTC element, the conductor track, and an insulating layer provided in the receiving pocket.
7. The electric heating device according to claim 5, wherein the web provided in the connection chamber is connected to a cover element covering the connection chamber.
8. The electric heating device according to claim 1, wherein at least one deformation projection is held under preload between at least one of the inner surfaces of the receiving pocket and an associated heat extraction surface of the PTC element.
9. The electric heating device according to claim 8, wherein the deformation projection is clamped under preload in the receiving pocket between one of the inner surfaces of the receiving pocket and the associated heat extraction surface of the PTC element and abuts against the inner surface.
10. The electric heating device according to claim 8, wherein the deformation projection is formed obliquely relative to the heat extraction surface in a direction toward an inlet opening of the connection chamber and in a direction toward the connection chamber.
11. The electric heating device according to claim 8, wherein the deformation projection comprises a tip that claws into the inner surface of the receiving pocket.
12. The electric heating device according to claim 8, wherein the deformation projections are attached to the pressure element.
13. The electric heating device according to claim 8, wherein at least one respective deformation projection is provided between each of the heat extraction surfaces and the associated inner surfaces of the receiving pocket.
14. The electric heating device according to claim 8, wherein two PTC elements are provided in the receiving pocket between which at least one deformation projection is provided.
15. The electric heating device according to claim 8, further comprising a pocket-shaped pressure element which accommodates the PTC element and at least one of the conductor tracks and which is provided with the at least one deformation projection on at least one of its outer surfaces adjoining the heat extraction surfaces.
16. The electric heating device according to claim 8, wherein the deformation projections are formed discretely and are distributed in a planar manner over the heat extraction surfaces.
17. The electric heating device according to claim 5, wherein the pressure element comprises at least one web.
18. The electric heating device according to claim 12, wherein the pressure element has a wedge-like cross-sectional shape.
19. The electric heating device according to claim 17, wherein the pressure element comprises at least one side section which is provided between one of the heat extraction surfaces and the associated inner surface and from which a plurality of webs protrude.
20. The electric heating device according to claim 18, wherein webs provided at an upper end of the receiving pocket near the connection chamber are longer than the webs provided at a lower end of the receiving pocket.
21. The electric heating device according to claim 20, wherein the webs are clamped under preload in the receiving pocket between the inner surface of the receiving pocket and the associated heat extraction surface.
22. The electric heating device according to claim 21, wherein the webs are formed obliquely relative to the heat extraction surface and inclined in the direction toward the connection chamber.
23. The electric heating device according to claim 17, wherein the webs are formed integrally with the pressure element.
24. The electric heating device according to claim 17, wherein the pressure element is an extruded section integrally forming the oppositely disposed side sections and a base section connecting them.
25. A method for the manufacture of an electric heating device comprising a housing having a partition wall which separates a connection chamber from a heating chamber for dissipating heat and from which at least one receiving pocket, protruding into the heating chamber as a heating rib protrudes, a PTC heating element being accommodated in the housing, the PTC heating element including at least one PTC element and conductor tracks for energizing the PTC element with different polarities, the conductor paths being electrically conductively connected to the PTC element and which being electrically connected in the connection chamber, and a pressure element accommodated in the housing and holding heat extraction surfaces of the PTC element abutted against oppositely disposed inner surfaces of the receiving pocket, the method comprising: introducing the PTC heating element into the receiving pocket; then introducing a pressure element into the receiving pocket for heat-conductive abutment of the heat extraction surfaces of the PTC element against the oppositely disposed inner surfaces of the receiving pocket and then, at least one of 1) deforming deformation projections so as to be distributed in a planar manner over the heat extraction surfaces, and 2), when the connection chamber is closed with a housing cover, providing a holding web on the housing cove in abutment against the PTC heating element.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] 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:
[0052] FIG. 1 shows a perspective top view of an embodiment of a pressure element according to an embodiment of the invention;
[0053] FIG. 2 shows a perspective side view of an embodiment of a heater housing with the pressure element according to FIG. 1;
[0054] FIG. 3 shows a cross-sectional view of the embodiment shown in FIG. 2;
[0055] FIG. 4 shows a top view onto the embodiment shown in FIGS. 2 and 3;
[0056] FIG. 5 shows a perspective face view of an embodiment of an electric heating device with the heater housing partially removed;
[0057] FIG. 6 shows a cross-sectional view of the embodiment shown in FIG. 5;
[0058] FIG. 7 shows the detail of FIG. 6 in an enlarged view;
[0059] FIG. 8 shows a side view of an alternative embodiment of a heater housing for realizing the present invention;
[0060] FIG. 9 shows a top view of the heater housing shown in FIG. 8;
[0061] FIG. 10 shows a perspective side view of the embodiment of a heater housing shown in FIGS. 8 and 9 after the deformation;
[0062] FIG. 11 shows a cross-sectional view of the heater housing according to FIGS. 8 to 10 together with the PTC element accommodated therein;
[0063] FIG. 12 shows an illustration according to FIG. 6 for a further embodiment of the present invention;
[0064] FIG. 13 shows a side view of an embodiment of a pressure element for realizing an embodiment of the present invention;
[0065] FIG. 14 shows a top view of the pressure element shown in FIG. 13;
[0066] FIG. 15 shows a perspective side view of the embodiment of a pressure element shown in FIGS. 13 and 14 after the deformation;
[0067] FIG. 16 shows a cross-sectional view of the pressure element according to FIGS. 13 to 15, together with the PTC element accommodated therein
[0068] FIG. 17 shows a perspective face view of an embodiment of an electric heating device, with the pressure element partially removed;
[0069] FIG. 18 shows a cross-sectional view of the embodiment shown in FIG. 17 and
[0070] FIG. 19 shows the detail of FIG. 18 in an enlarged view.
DETAILED DESCRIPTION
[0071] FIG. 1 shows an embodiment of a pressure element 2 according to the invention comprising a sheet metal strip identified with reference number 4 from which deformation elements 6 are worked out by punching and bending. The deformation elements 6 are formed by punching out lateral edges 7 and bending webs 8 resulting therefrom. The webs 8 are each connected with one of their two end sides to the base material of the sheet metal strip 4. A deformation projection 6 projecting from the sheet metal strip 4 with a relatively high spring rigidity is formed by each of the webs 8.
[0072] A straight line can be applied at the respective outer surface points of the individual deformation elements 6. The oppositely disposed lines connecting the sheet metal strip 4 forms an angle of less than 10 with the plane of the sheet metal strip 4 (cf. FIG. 1). Details of the PTC heating element can be gathered from FIGS. 2 to 4. The PTC heating element is identified there with reference number 10 and has a heater housing 12 made of plastic material which is formed to be frame-shaped with an upper rim 14 projecting beyond the frame in the thickness direction and a frame opening 16 in which four PTC elements 18 are provided one above the other. As shown in FIG. 3, conductor tracks in the form of contact plates 20 abut in an electrically conductive manner against both sides of the PTC elements 18. The contact plates 20 are connected to the heater housing 12, for example, by adhesive bonding. On one side (the right one in FIG. 3), the contact plate 20 is covered with an insulating layer 22. This insulating layer can be a plastic film or a ceramic plate or a combination of a ceramic plate with a plastic film. The plastic film is typically located on the outer side of the ceramic plate, which has the advantage that the plastic film can compensate for a certain roughness on an inner surface of a receiving pocket and thus absorb stress peaks that could impair the ceramic layer. The receiving pocket is marked with reference number 24 in FIGS. 5 and 6, the inner surface with reference numeral 26 in FIG. 6.
[0073] On the side opposite the insulating layer 22, the contact plate 20 there forms the outer surface of the layer structure. The pressure element 2 already described in FIG. 1 is disposed adjoining this outer surface. FIGS. 2 and 3 show the pressure element 2 before the layer structure is braced in the receiving pocket 24. The pressure element 2 is in a raised position. The upper end 28 of the pressure element 2 is located in the region of the rim 14. The lower end of the pressure element 2, identified with reference numeral 30, is located at the medium height of the lower PTC element 18.
[0074] The assembly of the heater housing 12 and the pressure element 2 shall be explained below with reference to FIGS. 5 and 6. They show an embodiment of an electric heating device with a housing base 102 and a housing cover 104. The housing base 102 comprises a circulation chamber 106 which is connected via ports, of which only one port 108 is shown in FIG. 5, to a line for a liquid fluid to be heated. The electric heating device is, in particular, an electric heating device in a motor vehicle.
[0075] The circulation chamber 106 is penetrated by several heating ribs 110 extending in the longitudinal direction of the housing base 102 and in a cross-sectional view having a substantially U-like cross-sectional shape and are circumferentially enclosed with respect to the circulation chamber 106. These heating ribs 110 form the previously mentioned receiving pocket 24. In the embodiment shown, the electric heating device has adjacently disposed pockets which extend substantially over the entire length of the housing base 102. The receiving pockets 24 are considerably longer than the heater housing 12. In the longitudinal direction of the receiving pocket 24, several heater housings 12 fit one behind the other into the receiving pocket 24 (cf. FIG. 5).
[0076] The housing base 102 forms a partition wall 112, which separates the circulation chamber 106 from a connection chamber 114, in which connection strips are exposed which are electrically conductively connected to the contact plates 20, are presently formed integrally thereon. In the embodiment shown in FIGS. 5 and 6, two connection lugs 32 are provided for each PTC heating element 10 for energizing the PTC elements 18 with different polarities.
[0077] The embodiment according to FIGS. 2 to 4 can be guided by the contemplation that the power current for energizing the PTC elements 18 drops to ground, which in the present case can be formed by the housing base 102, so that only one of the contact plates 20 needs to be connected to a connection lug 32, whereas the other polarity is given through the electrical connection of the housing base 102 to ground. The power current then flows over the inner surface 26 and through the pressure element 2.
[0078] Both connection options are conceivable.
[0079] For the assembly, the PTC heating element 10 is pushed into the receiving pocket 24 until a stop 34 formed by the rim 14 abuts against the upper side of the partition wall 112. As a result, the heater housing 12 and therefore the PTC heating element 10 is positioned relative to the housing 100. The insulating layer 22 is then disposed immediately adjacent to the corresponding inner surface 26. On the opposite side, the pressure element 2 is in its initial position between the inner surface 26 and the associated contact plate 20. The layers of the layer structure are not yet abutted against each other under preload.
[0080] The pressure element 2 is now pushed towards the lower end of the receiving pocket which is identified with reference numeral 36. The deformation segments 6 are resiliently preloaded with this relative motion of the pressure element 2. In the same way, the layers of the layer structure are abutted against one another and the insulating layer 22 against the associated inner surface 26 of the receiving pocket 24. The introduction of the pressure element 2 in this manner can be path-controlled or force-controlled. The force there is the degree of tension in the layers of the layer structure. After a certain preload force corresponding to an axial compressive force for introducing the pressure element 2 has been reached, the insertion motion of the pressure element 2 into the receiving pocket 24 can terminate.
[0081] Alternatively or in addition, a lower stop can be provided which defines the maximum insertion distance of the pressure element 2. Such a lower stop can be formed, for example, by a cross web formed at the lower end of the heater housing 12 and drawn in with reference numeral 38 in FIGS. 2 and 3. Alternatively, such a cross web 38 can be omitted, so that the insertion motion of the pressure element 2 is defined by the lower end 36 of the receiving pocket 24. The sheet metal strip 4 can equally well be provided wider than a sliding guide for the pressure element 2, identified with reference numeral 40, which is formed on the heater housing 12 and can be seen in FIG. 2. This widening on the upper side forms a stop which interacts with the rim 14 and defines the maximum insertion depth of the pressure element 2.
[0082] FIG. 6 shows the pressure element 2 in the receiving pocket 24 on the right-hand side after the introduction into the receiving pocket 24 and in the receiving pocket 24 provided on the left-hand side adjacent thereto prior to the introduction for bracing the elements of the layer structure. The deformation projections 6 have deformed resiliently as a result of the insertion and abut against the inner surface 26. The layers of the layer structure are abutted against each other. The layer structure is abutted in a planar manner on the side opposite the pressure element 2 against the inner surface 26 provided there. Pressing the pressure element 2 into the receiving pocket 24 can be carried out with a tool which on one face side has a groove that is adapted to receive the sheet metal strip 4 and that grips the sheet metal strip 4 at the end.
[0083] Thereafter, a preferably permanently elastic plastic mass, to which good heat-conductive but electrically non-conductive filler particles are added, for example, particles made of aluminum oxide, can be filled into the receiving pocket 24 in order to fill it entirely and to displace the air remaining therein. This results in good heat conduction between the elements of the layer structure and all surfaces defining the receiving pocket 24 on the inside.
[0084] FIG. 7 shows an enlarged detail of FIG. 6. As shown, the deformation projections 6 are provided by edges having a sharp-edged tip 42. The tip 42 acts like a barb that inhibits any movement in the opposite direction. The sheet metal strip can be firmly connected to the PTC heating element, for example, be adhesively bonded thereto. The deformation projections 6 are inclined in the direction toward the insertion opening of the receiving pocket 24 which is closed on the underside. When the sheet metal strip 4 is introduced, the deformation projections 6 are bent in the direction toward the sheet metal material of the sheet metal strip 4. The sheet metal strip 4 can optionally be introduced into the receiving pocket 24 together with other elements of the PTC heating element 10, while the deformation projections 6 are bent due to their inclination in the direction toward the planar sheet metal strip 4. In this way, the PTC heating element 10 can be introduced into the receiving pocket 24 while the deformation projections 6 scrape along the inner surface 26. In the installation position shown in FIG. 7, the tips 42 are clawed to the inner surface 26 of the receiving pocket 24 and are therefore connected in a positive-fit or force-fit manner, respectively.
[0085] To better retain the installation position of the PTC heating element 10 in the receiving pocket 24, the PTC element 18 can be adhesively bonded to the contact plates 20 and the sheet metal strips 4, optionally to further layers within the receiving pocket 24, such as an insulating layer 22.
[0086] In FIG. 7, the sheet metal strip 4 shown on the left-hand side abuts directly against the associated contact surface. The deformation projections 6 claw to the inner surface 26 of the receiving pocket 24. This results in electrical contact between the metallic housing 100 and the contact plates 20. The PTC element 18 is therefore connected to the ground on the left-hand side in FIG. 7, which is formed by the housing 100.
[0087] The insulating layer 22 is located on the right-hand side according to FIG. 7 between the sheet metal strip 4 and the contact plate 20. The contact plate 20 provided there is provided with a connection lug, not shown in FIG. 7, which projects beyond the opening of the receiving pocket 24 and is exposed in the connection chamber 114. In contrast, the extension of the contact plate 20 on the left-hand side is limited to the region of the receiving pocket 24.
[0088] FIG. 8 shows a side view of an alternative embodiment of a heater housing 44 which is presently configured as an extruded section made of a metal and in a top view according to FIG. 9 has a basically rectangular base area. Retaining webs 46 protrude from opposite end faces of this rectangular base area, and, as illustrated in FIG. 8, each protrude from the same surface of the section. The side view further illustrates that the section forms a base section 48 as well as two basically identical side sections 50. Integral hinges 52 are formed by reducing the material thickness of the profile between the respective sections 48, 50.
[0089] Each of the side sections 50 has a wedge-like cross-sectional shape. A plurality of deformation projections 6 formed integrally on the section protrude from an outer surface. As illustrated in FIG. 10, the deformation projections 6 are presently designed as ribs that are formed end-to-end over the width of the extruded section. The deformation projections 6 taper sharply toward their free end identified with reference numeral 54.
[0090] For the producing the embodiment, the extruded section according to FIGS. 8 and 9 is first drawn. Lengths are thereafter cut off as illustrated in FIG. 9. The side sections 50 are bent relative to the base section 48 around the integral hinges 52. This results in a receptacle 56 for the PTC heating element which is shown in FIG. 11 with the PTC elements 18 and the contact plates 20 abutting thereagainst on oppositely disposed main side surfaces. The main side surface of the PTC element 18 is formed by the largest side surface of this PTC element 18. The main side surface corresponds to the heat extraction surface which is identified with reference numeral 58. There is an insulating layer 22 respectively disposed on the side of the contact plate 20 opposite to the heat extraction surface. The PTC heating element 10 according to FIG. 11 is accordingly electrically separated from the heater housing 44 by the insulating layers 22. Each individual contact plate 20 forms a connection lug 32 for the electrical connection of the PTC heating element 10. The retaining webs 46 evidently protrude over the upper PTC element 18. The retaining webs 46 can be designed as engagement elements which secure the side sections 50 with the PTC heating element 10 against one another when the pressure element 44 is fitted. Even more, however, the retaining webs 46 prevent the PTC heating element 10 from migrating out of the heater housing 44 after it has been installed in the receiving pocket 24.
[0091] For assembly, the heater housing 44 is first equipped with the insulating layers 22 and the PTC heating element 10. The retaining webs 46 are then locked, whereby the pressure element 44 is closed. The unit thus preassembled is introduced into the receiving pocket 24. The deformation webs 6 deform in this process. Due to their sharply tapering ends 54, the deformation webs 6 in the installed position claw into the inner surface 26 of the receiving pocket 24, so that the heater casing 44 together with the PTC heating element 10 is permanently held securely in the installed position within the receiving pocket 24. In one variant, the heater housing 44 can also be formed having several parts. For example, an extruded section can define the wedge-shaped configuration which corresponds substantially to the geometry of the receiving pocket 24. A sheet metal strip 4, which has been described with reference to FIGS. 1-6, can be abutted on the outer side against this extruded section. Deformation projections 6 can there protrude from the sheet metal strip 4 on both sides in order to interact, firstly, with the inner surface 26 of the receiving pocket and, secondly, with the outer surface of the heater housing 44.
[0092] FIG. 12 shows an alternative embodiment based on the illustration according to FIG. 6. Identical components are marked with the same reference symbols.
[0093] The embodiment according to FIG. 12 shows the housing 100 covered with a housing cover 104 which forms a cover element of the invention. This housing cover 104 seals the connection chamber 114 and can have plug contacts for introducing the power current and/or for control signals of a control device provided in the connection chamber 114. The housing cover 104 carries a holding element 60 manufactured from plastic material from which holding webs 62 protrude. The holding webs 62 are each associated with a connection lug 32. A female plug element identified with reference numeral 64 is pushed onto the connection lug 32 and connected to a connecting cable, the wire of which is identified with reference numeral 66. The holding web 62 abuts against the free end of this female plug element 64. It has a U-shaped receptacle that engages around the female plug element 64 in the region of the wire 66. In this way, firstly, the electrical plug connection between the connection lug 32 and the female plug element 64 is secured. Secondly, the holding web 62 presses indirectly against the connection lug 32, as a result of which the heater housing 12 and therefore the PTC heating element 10 are secured in position in the receiving pocket 24. The U-shaped receptacle can be formed to be funnel-shaped at its open end.
[0094] FIG. 13 shows a side view of a pressure element 202 which in the present case is configured as an extruded section made of a metal and in a top view according to FIG. 2 has a basically rectangular base area. Retaining webs 204 protrude from opposite end faces of this rectangular base area, and, as illustrated in FIG. 13, each protrude from the same surface of the profile which is a boundary surface 206 of a receptacle identified with reference numeral 208 (cf. FIG. 3). The side view further illustrates that the section forms a base section 210 as well as two basically identical side sections 212. Integral hinges 214 are formed by reducing the material thickness of the profile between the respective sections 210, 212.
[0095] Each of the side sections 212 has a wedge-like cross-sectional shape. A plurality of webs 216 formed integrally on the section protrude from an outer surface. As illustrated in FIG. 15, the webs 216 are presently designed as ribs that are formed end-to-end over the width of the extruded section. The webs 16 taper sharply toward their free end identified with reference numeral 218.
[0096] For the producing the embodiment, the extruded section according to FIGS. 13 and 14 is first drawn. Lengths are thereafter cut off as illustrated in FIG. 14. The side sections 212 are bent relative to the base section 10 around the integral hinges 214. This results in the receptacle 208 for a PTC heating element 220 which is shown in FIG. 16 with the PTC elements 222 and the contact plates 224 abutting thereagainst on oppositely disposed main side surfaces. The main side surface of the PTC element 222 is formed by the largest side surface of this PTC element 222. The main side surface corresponds to the heat extraction surface which is identified with reference numeral 226. There is an insulating layer 228 respectively disposed on the side of the contact plate 224 opposite to the heat extraction surface 226. The PTC heating element 220 according to FIG. 16 is accordingly electrically separated from the pressure element 202 by the insulating layers 228. Each individual contact plate 224 forms a connecting lug 230 for the electrical connection of the PTC heating element 220. The retaining webs 204 evidently protrude over the upper PTC element 222. The retaining webs 204 can be designed as engagement elements which secure the side sections 212 against one another when the pressure element 202 is fitted with the PTC heating element 220. Even more so, however, the retaining webs 204 prevent the PTC heating element 210 from migrating out of the receptacle 208 of the pressure element 202 after it has been installed in a receiving pocket.
[0097] The receiving pocket, which is dealt with in FIG. 17 et. seq., can taper conically towards its lower closed end. The pressure element has an outer contour adapted to this cross-sectional shape, which is presently defined by a connecting line L that connects the free, sharply tapering ends 218 to one another and is identified with reference symbol L in FIGS. 13 and 16. The two connecting lines L marked in FIG. 16 form an angle of presently about 10. A base body of the pressure element, from which the webs 216 protrude, already has a slightly wedge-like basic shape. The webs 216 protruding from a lower end 232 of the pressure element 202 are shorter than the webs 16 protruding in the region of an upper end 234 of the pressure element. This reinforces the wedge shape predetermined by the base body.
[0098] In the assembled state, at least the boundary surfaces 206 extend parallel to one another and abut in a planar manner against the insulating layers.
[0099] The assembly of the pressure element 202 shall be explained below with reference to FIGS. 17 and 18. They show an embodiment of an electric heating device with a housing 100 having a housing base 102 and a housing cover 104. The housing base 102 comprises a circulation chamber 106 which is connected via ports, of which only one port 108 is shown in FIG. 17, to a line for a liquid fluid to be heated. The electric heating device is, in particular, an electric heating device in a motor vehicle.
[0100] The housing base 102 forms a partition wall 112 that separates the circulation chamber 106 from a connection chamber 114.
[0101] The circulation chamber 106 is penetrated by several heating ribs 110 extending in the longitudinal direction of the housing base 102 and in a cross-sectional view having a substantially U-like cross-sectional shape and are circumferentially enclosed with respect to the circulation chamber 106. These heating ribs 110 form receiving pocket 116
[0102] In the embodiment shown, the electric heating device has adjacently disposed pockets which extend substantially over the entire length of the housing base 102. The receiving pockets 116 are considerably longer than the pressure elements 202. In the longitudinal direction of the receiving pocket 116, several pressure elements 202 fit one behind the other into the receiving pocket 116 (cf. FIG. 5). The receiving pockets 116 on their longitudinal sides form oppositely disposed inner surfaces 118.
[0103] The connection lugs 230 are exposed in the connection chamber and are connected in an electrically conductive manner to the contact plates 116, which are presently formed integrally thereon. In the embodiment shown in FIGS. 17 and 18, two connecting lugs 232 are provided for each PTC heating element 210 for energizing the PTC elements 218 with different polarities.
[0104] For the assembly, the pressure element 2 is first fitted the insulating layers 22, the contact plates 224, and the PTC elements 222. For this purpose, these layers are introduced into the funnel-shaped receptacle 208 which has not yet been completely closed and is shaped approximately as shown in FIG. 15. The retaining webs 204 are then locked, whereby the pressure element 202 is closed. The unit thus preassembled is introduced into the receiving pocket 116. The webs 216 deform in this process. Due to their sharply tapering ends 218, the webs 206 in the installed position grip the inner surface 118 of the receiving pocket 116, so that the pressure element 202 together with the PTC heating element 220 is permanently held securely in the installed position within the receiving pocket 116.
[0105] FIG. 19 illustrates how the webs 216 grip into the inner surface 118 of the receiving pocket 116. This results in a positive-fit connection between the pressure element 202 and the metallic housing 100. The pressure element 202 is then possibly connected to ground which can be formed by the housing 100. A possible failure of the insulating layer 228 can then be determined by way of a ground monitor, which can be significant for high-voltage applications of the invention e.g. in the field of electromobility.
[0106] FIGS. 18 and 19 in particular illustrate that the webs 216 provided at a lower end of the receiving pocket 116 are shorter than the webs provided at the opposite end opening toward the connection chamber 114. Corresponding to the wedge shape of the receiving pocket 116, the pressure element 202 with its outer contour assumes a wedge shape, whereas the layers of the PTC heating element have a parallel orientation relative to one another and to the boundary surfaces 206 of the pressure element 202. The webs 216 are provided inclined toward the upper end of the receiving pocket and accordingly toward the inlet opening provided there which opens into the connection chamber 114. This results in a positive-fit connection of the webs 16, which taper sharply at the front, to the inner surface 118. The pressure element then holds the heat extraction surfaces 226 of the PTC element 222, with the interposition of the associated contact plate 224 and the associated insulating layer 228, against the inner surface 118 of the receiving pocket 116.
