EP3731595A1 - Ptc heating element and electric heating device comprising such a ptc heating element and method for producing a ptc heating element - Google Patents

Abstract

The present invention relates to a PTC heating element (22) for an electrical heating device, an electrical heating device with such a PTC heating element (22) and a method for producing the PTC heating element (22). The PTC heating element (22) has a housing (72) which contains at least one PTC element (30), conductor tracks (38) electrically connected to the PTC element (30) and insulating layers which are thermally conductive against the PTC element (30) (34) inserts as a unit and is surmounted by contact tongues (42) which are electrically conductively connected to the conductor tracks (38) with different polarity in order to energize the PTC element (30). To improve the heat extraction from the PTC element, the present invention proposes the receiving space (78) in a cross-sectional view through two opposing inner surfaces (88) that overlap the PTC element (30) and adjoining the inner surfaces (88) to delimit the longitudinal edges (88) of the housing (72) forming concave cavities, the diameter of which is greater than the distance between the inner surfaces (88). The electrical heating device has at least one PTC heating element (22) according to the invention arranged in a circulation chamber (14). In the method according to the invention, the housing (72) is first formed. The PTC element (30), the conductor tracks (38) and the insulating layers (34) are then introduced into the receiving space (78) through an opening (74) in the deep-drawn part (72) and finally the housing (72) is pushed through to edge areas deformation forces acting on the housing (72) are transformed so that opposing inner surfaces of the housing (72) are placed against the insulating layers (34).

Description

The present invention relates to a PTC heating element for an electrical heating device. The PTC heating element according to the invention has a housing which adds at least one PTC element, conductor tracks electrically connected to the PTC element and thermally conductive insulating layers lying against the PTC element as a unit and is surmounted by the contact tongues that supply current to the PTC element are electrically conductively connected with the conductor tracks with different polarity.

Such a PTC heating element is off, for example EP 2 190 256 A1 known. This PTC heating element has a frame which has frame openings extending through the frame, in each of which at least one PTC element is received, which is provided on both sides with contact plates forming the conductor tracks. There is an insulating layer on the side opposite the PTC element. These elements are coated with an adhesive, whereby the components of the PTC heating element carrying the power current are supposed to be sealed in from the outside of the PTC heating element.

A similar elongated PTC heating element is disclosed in US Pat EP 2 724 086 B1 , in which the aforementioned components forming a heating cell, namely the PTC element and the conductor tracks lying on it on both sides, are accommodated in a flat tube in the form of contact sheets with an insulating layer in between.

These two previously known proposals for a PTC heating element have the disadvantage that the tubes have to be closed on one side, as a result of which the PTC heating elements are longer than necessary. Such housings, designed as rectangular, round or oval tubes, are usually closed at the end by laser or electron welding. This additional process makes the production of the PTC element more expensive.

In addition, the required from EP 2 190 256 A1 known solution a large number of parts to seal the PTC element and the current-carrying conductor tracks from the environment. Leaks can occur at the phase boundaries between the individual components, which endangers electrical safety.

The same applies to the off EP 2 428 746 A1 known solution in which the PTC element is received in a tubular sheet metal which is formed by a sheet metal profile closed at the end. The flanging proposed for this in a cross-sectional view of the PTC heating element free ends of the sheet metal can also not ensure the necessary tightness.

The present applicant has with DE 10 2017 209 990 A1 a PTC heating element of the type mentioned is proposed, in which the current-carrying parts are arranged and sealed in ceramic shells. Here, too, there may be leaks at the joint between the two shell elements. The production of the previously known PTC heating element is also relatively expensive.

The same applies to the off EP 3 334 242 A1 known solution, in which the PTC element and the contact plates which are in contact with it as conductor tracks in an electrically conductive manner are encapsulated together with an insulation provided on the outside with a plastic frame that leaves the insulation free. In addition to the complex production, this solution has the disadvantage that the medium to be heated can reach the current-carrying parts between the frame and the surface of the insulating layer. A complete sealing of the current-carrying parts within the housing requires a particularly precise process control and inspection of the PTC heating elements produced.

The present invention is based on the problem of specifying a PTC heating element of the type mentioned above, which can be manufactured inexpensively and which allows the heat generated by the PTC element to be dissipated well.

To solve this problem, the present invention proposes a housing which forms a receiving space which is designed to be adapted to receive the PTC element, the conductor tracks and the insulating layers. This receiving space is formed by the housing, preferably by a deep-drawn part, the deep-drawn part already being closed on the underside after the forming process in the context of deep-drawing. Thus, the housing or the deep-drawn part has a cup-shaped configuration that is closed on the underside and is only open on one side. On this side, the contact tongues protrude beyond the housing so that the PTC element can be electrically connected on this side.

Insofar as the description of the present invention focuses on deep drawing, it is also to be understood as a synonym for extrusion.

The housing is preferably formed from sheet metal by forming. A die and a punch preferably work together, the punch penetrating into the sheet metal material this drives ahead. The sheet metal is diverted from the die and follows the movement of the punch. At the end, a pot-shaped component is obtained which is closed on the underside. The component consists of a metal sheet, so that the walls delimiting the receiving space are made of a material with good thermal conductivity. The sheet can for example be a copper sheet or an aluminum sheet. The housing is preferably formed from a cylindrical profile that is closed on one side and initially produced as an endless material. The housing is preferably made of Al 99.5 or aluminum with a low proportion of Si, the proportion of Si not exceeding 5% by weight.

According to the invention, the receiving space is delimited in a cross-sectional view by two opposing, regularly aligned parallel to one another and covering the PTC element, flat inner surfaces and cavities, which adjoin the inner surfaces. These cavities are delimited on the outside by outer longitudinal edges of the housing which extend in the vertical direction of the PTC element. Deformation segments, which are plastically deformed in the direction of the receiving space, are provided between these outer longitudinal edges and the flat inner surfaces. The deformation segments are plastically deformed with respect to the inner surfaces and preferably the longitudinal edges. The deformation segments are then plastically deformed relative to the inner surfaces and preferably the outer longitudinal edges. The deformation segments usually adjoin the inner surface directly. In a cross-sectional view, the deformation segments lie in the edge region of the receiving space and thus of the housing, but within the outer longitudinal edge. As a result of the plastic deformation, the inner surfaces are placed against the PTC element under elastic pretension and with the insulating layer and the conductor track in between.

The cavities are preferably concave on the outside, for example polygonal, oval or circular segment-shaped and have a diameter which is greater than the distance between the inner surfaces. This specification relates to the finished product as well as the housing before forming, in which the inner surfaces, which initially leave a free space for introducing the insulating layer together with the conductor tracks and the PTC element, are moved towards one another in order to be preloaded against the outer surfaces of the Apply insulation layer. The PTC element or elements in the receiving space are covered by the inner surfaces. The inner surface of the housing thus covers the main side surface of the PTC element and can preferably only protrude slightly above it. The special design of the receiving space facilitates the elastic contact of the inner surfaces against the outer surfaces of the insulating layers.

In the method according to the invention, the deformation takes place in the area of the cavities, i.e. by a deformation force acting exclusively against the longitudinal edges of the housing. However, the diameter is not necessarily only to be understood as the inner dimension of a cavity with a circular segment shape in cross section. The cavity can also have other shapes. It can have an oval or polygonal cross-sectional shape. Above all, it is essential that the dimension of the cavity in the direction of the distance between the inner surfaces is greater than this distance and that the outer surface of the cavity or the deformation segments the outer surface of the housing where the housing is to be placed with its inner surface on the insulating layer, towers. This is because a forming tool acting against the edge regions of the housing engages this outer surface of the housing and applies the inner surfaces to the insulating layers with a certain prestress.

The insulating layer preferably comprises a layer made of an elastomer or silicone. The thickness of the insulating layer should be a few tenths of a millimeter. For example, 1/10 to 3/10 mm. The insulating layer should have certain damping properties in order to compensate for local stresses when pressing the housing in such a way that the PTC element does not break. The insulating layer can have a ceramic plate, in particular an Al ₂ O ₃ plate, preferably as a further layer in connection with the above-mentioned plastic layer and optionally an adhesive layer.

The housing preferably has at least one reinforcement, preferably formed by the deep-drawn part, which holds at least two of the PTC element, conductor track and insulating layer against one another under prestress in the housing. The PTC element, the conductor tracks and the insulating layers provided on the outside are usually received as parallel layers in the receiving space. The insulating layers can be made in one piece, for example by turning over a film that connects two insulating layers to one another via a lower fold. In the present case, that area of the PTC element which is provided close to the closed end of the deep-drawn part is referred to as the bottom. The closed end is usually that end which is provided in front of the punch in the direction of movement of the punch during deep drawing.

The reinforcement of the housing is preferably provided in the area of the outer longitudinal edges and / or in the area of the inner surfaces. In contrast, the deformation segments in which the plastic deformation takes place are less pronounced. The reinforcement can be formed by shaping and / or thicker walls. The aforementioned spherical design is a type of reinforcement of the housing in the area of the outer longitudinal edges.

The reinforcement on the housing can be formed by a stiffening rib produced by means of deep drawing or a spherical configuration of opposite main side walls of the housing or parts of these walls. This spherical configuration is shown on the outside of the housing, whereas the inner surfaces corresponding to it are plane-parallel and bear against the insulating layers. In the case of a convex configuration, the inner surface is flat and extends parallel to a main side surface of the PTC element, whereas the outer side of the housing is convex opposite to the main side surface. Accordingly, in a cross-sectional view, the housing has a greater thickness in the center of the inner surface than at the edge of the inner surface. The convex design can be essential to the invention, i.e. the features of claim 3 can define a PTC heating element according to the invention with the preamble features of claim 1.

In a cross-sectional view, the thickness ratio between the largest and smallest wall thickness of the housing should be between 3/1 and 5/1. The smallest wall thickness should preferably not be greater than 1mm.

In any case, the present invention proposes to improve or ensure the close contact of the PTC element, conductor tracks and insulating layers, which is preferable for good heat extraction, by means of a pretensioning force established by the housing. Of course, the above-mentioned parts can first be glued in the context of pre-assembly. The bond between the PTC element and the conductor tracks is usually cured under pressure so that these layers are kept as close as possible to one another until the adhesive has cured. The same applies to the insulation layers. In any case, the pretensioning ensures that the housing rests on the outside against the insulating layer under pretension, the pretensioning being passed on to the phase boundary to the conductor track and / or the PTC element even in the case of previous gluing.

The conductor track can be electrically contacting and connected to the main side surface of the PTC element. The conductor track can be a continuous sheet of metal. The conductor track can also be formed by a metal structure provided with openings, for example a metal grid, an expanded metal or a metal mesh. The conductor tracks can be applied entirely or partially in an electrically conductive manner against the end faces of the PTC element. In this case, the main side surfaces of the PTC element are usually hardly or not at all covered with the conductor track. Thus, the heat extraction does not have to take place via the main side surface through the conductor track.

The main side area of the PTC element is usually understood to be the largest area of the PTC element. PTC elements are usually cuboid or plate-shaped. An edge surrounding the main side surfaces usually has a height of less than one tenth of the length or the width of the PTC element, the width and length spanning the main side surface.

According to a preferred development of the present invention, the PTC heating element according to the invention has a ground connection tongue that is electrically connected to the housing. This ground connection tongue can protrude from the housing in a direction parallel to the extension direction of the contact tongues. The ground connection tongue is used for the electrical connection of the housing to a ground pole. Furthermore, the housing can have a retaining rib opposite the contact tongues. In the case of a housing designed as a deep-drawn part, this retaining rib is usually formed by deep-drawing. After deep-drawing, the housing does not require any post-processing to form the corresponding retaining rib. The holding rib is usually provided in order to position the housing in a heating housing, which for this purpose has a receptacle adapted to receive the holding rib on its arch, as is basically the case EP 3 334 242 A1 is known for another example of a PTC heating element. If the heater housing has electrically conductive properties or at least forms an electrically conductive base, the housing of the PTC heating element according to the invention can be electrically connected via the retaining rib. The PTC heating element with its housing is connected to ground via the bottom of the heater housing.

According to a preferred development of the present invention, the PTC heating element according to the invention has a sealing element made of a flexible plastic, which seals an opening in the housing and is protruded by the contact tongues. This seal is usually shaped as a labyrinth seal. This sealing element consists e.g. made of a flexible plastic such as silicone or TPE.

The housing usually forms a collar which is circumferentially surrounded by a labyrinth seal of the sealing element. This collar leads to a certain stiffening in the area of the seal, so that the sealing element can be inserted with good press-in force into a female plug contact receptacle of a heater housing, which has a connection chamber for the electrical connection of the PTC element and a circulation chamber that is separated from each other via a partition of the heater housing are separated fluid-tight. This results in a good seal in the area of the female plug-in element receptacle. In addition, that PTC heating element positioned through the plug contact in the partition and held at least temporarily for assembly purposes.

With a view to compensating for tolerances and for improved sealing within the female plug contact receptacle, it is proposed according to a preferred embodiment of the present invention that the sealing element protrudes beyond the housing in the longitudinal direction of the contact tongues. When it is inserted into the female plug-in element receptacle of the heater housing, the sealing element can accordingly be compressed in the insertion direction, so that the sealing element expands in the female plug-in element receptacle and fills it as completely as possible, thereby improving the tightness.

According to a preferred development of the present invention, the housing has a retaining edge in particular to counter this compression movement of the sealing element. The sealing element rests against this retaining edge. The retaining edge is usually formed by the deep-drawn part itself and is therefore the result of a deformation of the sheet metal material during deep-drawing of the housing.

The PCT heating element preferably has a lead-through segment made of an electrically insulating material, which is inserted in the manner of a plug into a free end of the deep-drawn part through which the contact tongues protrude and which forms lead-through channels for the contact tongues. This lead-through segment gives the contact tongues a lateral guide in the area in which they are extended beyond the housing. In addition, the leadthrough segment prevents direct electrical contact between the contact tongues and the housing made of sheet metal, so that the insulation of the electrically conductive housing is not impaired. The lead-through segment is preferably designed in one piece with a frame which surrounds the PTC element at least partially, usually completely. The frame usually forms a receiving opening for the at least one PTC element, which is formed by frame spars completely surrounding the PTC element, which are usually arranged as thin webs between the PTC element and the inner wall of the deep-drawn part.

The bushing segment can be formed in one piece with the aforementioned frame and form half-shells for guiding the contact tongues, in which the contact tongues are circumferentially guided, held and insulated after a bushing segment cover has been placed on the bushing segment. The connection between the frame and the leadthrough segment cover is usually made by hot caulking of pegs, which penetrate holes recessed in the contact tongues, so that the contact tongues and the conductor tracks attached to them are prepositioned. The conductor tracks are preferably formed from sheet metal as contact sheets. They usually have form-locking elements at their lower end, which are formed from the sheet metal material by punching and bending and are engaged in receptacles that are formed by the frame, in particular by our cross member of the frame. Thus, a preassembled assembly can be generated by the frame, which combines the frame, the lead-through segment and the two contact plates and the PTC element (s) provided in between to form a unit. The bushing segment consists of the bushing segment provided on the frame side and the bushing segment cover.

According to its independent claim, the present invention proposes an electrical heating device with at least one PTC element of the type described above arranged in a circulation chamber, the contact tongues protruding from the housing protruding through a partition into a connection chamber of a heater housing, in which the contact tongues are used for energizing of the PTC element are connected to a power source with different polarity. The partition of the heater housing forms a female plug contact receptacle in which the PTC element is usually inserted in a sealed manner, preferably held in a frictionally engaged manner via the sealing element, at least for assembly purposes.

With its further secondary aspect, the present invention proposes a method for producing a PTC heating element of the type mentioned at the beginning. In this method, the PTC element, the conductor tracks and the insulating layer are introduced into a receiving space of the housing through an opening formed through the housing. The housing was preferably designed as a deep-drawn part beforehand. The direction in which the punch drives the sheet metal material in front of it corresponds to the direction in which the aforementioned elements are introduced into the receiving space. The deep-drawing only forms one opening to the receiving space. Opposite the opening, the deep-drawn part is closed, since only the formed sheet metal is provided on this side.

In a further process step, the housing is finally reshaped by circumferential forces acting solely on the edge areas of the housing, so that opposing inner surfaces of the housing are placed against the components introduced into the receiving space, i.e. the PTC element, the conductor tracks and / or the insulating layer . The function of the insulating layer, which is one or more layers, is to interact directly with the inner surfaces of the housing, ie to rest against them. These inner surfaces are usually parallel to the main side surfaces of the PTC element.

The deformation forces act exclusively on those areas of the deep-drawn part which, as an edge, lie outside a projection surface of the main side surfaces of the PTC element on the inner surface of the housing. Accordingly, the deformation forces do not act directly against the main side surfaces of the PTC element and the layers resting against them, for example the insulating layers. A gentle deformation of the housing is achieved in this way. In addition, the material of the housing can be reshaped between the lateral edges, which in the preferred deep-drawing usually extend parallel to the direction of movement of the punch, and the layers provided in the receiving space, so that a certain pretension can be achieved by externally convex curvature of the edge areas, with which the inner surfaces rest against the layers introduced into the receiving space. To this end, it is preferable to arrange a frame made of an insulating material, in particular made of plastic, with its longitudinal spars immediately adjacent to the edges of the deep-drawn part and to provide a free space between these longitudinal spars and the PTC element in which the sheet metal material the housing is pushed during forming. This free space may be covered by the insulating layer, which can be applied as a plastic film over the PTC element or the conductor track and at the same time at least partially covers the longitudinal bars. This ensures that the deformation of the housing does not lead to any direct electrical contact between parts of the housing, for example with the circumferential edge of the PTC element or with a conductor track lying against it.

The reshaping is preferably carried out in a die with an upper part and a lower part, which have shaped surfaces that interact with the outside of the deep-drawn part outside the PTC element, that is to say laterally next to the PTC element as described above.

The deep-drawn part is preferably formed in the die with a block pressing. In the context of this block pressing, at least the opposing longitudinal edges of the housing are framed both on the upper and lower sides in the direction of movement of the die and at right angles thereto and thus on the edge side. This prevents the metallic material of the deep-drawn part from evading the forming movement to the outside. Rather, this results in a deformation of the inwardly directed curvature of a usually convex longitudinal edge of the housing. Depending on the tolerances of the housing, but in particular of the components accommodated in the receiving space, the deformation can be more or less pronounced. However, the process is set in such a way that the forming movement results in a pretensioned contact between the components of the PTC heating element accommodated in the receiving space.

Figur 1

eine perspektivische Seitenansicht eines Ausführungsbeispiels einer elektrischen Heizvorrichtung;

Figur 2

eine perspektivische Seitenansicht des Ausführungsbeispiels nach Figur 1 nach Anschluss der PTC-Heizelemente;

Figur 3

eine perspektivische Explosionsdarstellung des PTC-Heizelementes der in den Figuren 1 und 2 gezeigten elektrischen Heizvorrichtung;

Figur 4

eine perspektivische Seitenansicht des in Figur 3 verdeutlichten Ausführungsbeispiels eines PTC-Heizelementes;

Figur 5

eine perspektivische Längsschnittansicht entlang der Linie V-V gemäß der Darstellung in Figur 4 vor dem Verpressen des PTC-Heizelement;

Figur 6

eine perspektivische Querschnittansicht entlang der Linie VI-VI gemäß der Darstellung in Figur 4 vor dem Verpressen des PTC-Heizelement;

Figur 7

eine perspektivische Längsschnittansicht entlang der Linie V-V gemäß der Darstellung in Figur 4 nach dem Verpressen des PTC-Heizelement;

Figur 8

eine perspektivische Querschnittansicht entlang der Linie VI-VI gemäß der Darstellung in Figur 4 nach dem Verpressen des PTC-Heizelement und

Figur 9

eine Querschnittansicht des Ausführungsbeispiels des PTC-Heizelementes nach den Figur 3 bis 8 beim Verpressen in einem Gesenk.

Further details and advantages of the present invention emerge from the following description of an exemplary embodiment in conjunction with the drawing. In this show:

Figure 1

a perspective side view of an embodiment of an electrical heating device;

Figure 2

a perspective side view of the embodiment according to Figure 1 after connecting the PTC heating elements;

Figure 3

a perspective exploded view of the PTC heating element of the electrical heating device shown in Figures 1 and 2;

Figure 4

a perspective side view of the in Figure 3 illustrated embodiment of a PTC heating element;

Figure 5

a perspective longitudinal sectional view along the line VV as shown in FIG Figure 4 before pressing the PTC heating element;

Figure 6

a perspective cross-sectional view along the line VI-VI as shown in FIG Figure 4 before pressing the PTC heating element;

Figure 7

a perspective longitudinal sectional view along the line VV as shown in FIG Figure 4 after pressing the PTC heating element;

Figure 8

a perspective cross-sectional view along the line VI-VI as shown in FIG Figure 4 after pressing the PTC heating element and

Figure 9

a cross-sectional view of the embodiment of the PTC heating element according to Figures 3 to 8 when pressing in a die.

Figure 1 shows a perspective top view of a heater housing, identified with reference number 2, of an electrical heating device designed as a water heater. The heater housing 2 has a housing pan element 4 made of plastic. The heater housing 2 forms an inlet connector 6 and an outlet connector 8, which in the present case are formed in one piece on the housing pan element 4. The nozzles 6, 8 are designed as hose connection nozzles and form an inlet opening 10 or an outlet opening 12 to a circulation chamber identified by reference numeral 14.

The circulation chamber 14 is separated from a connection chamber 18 by a partition 16 made of plastic and is sealed off from the latter. The partition 16 forms female plug-in element receptacles 20 for PTC heating elements 22, which are inserted sealingly into the female plug-in element receptacles 20 and are supported on a base 24 of the housing pan element 4.

The Figures 3 to 9 illustrate details of the PTC heating element 22, which in the present case only has one PTC element 30, which is covered with an insulating layer 34 on its mutually opposite main side surfaces 32. In the present case, the insulating layers 34 are formed by a plastic film, for example from Kapton. The PTC element 30 is designed as a plate with a width B and a length L which are greater by a factor of at least 10 than a thickness which corresponds to the distance between the two main side surfaces 32.

Contact plates 38 are provided on opposite main side surfaces 32, which are glued to the PTC element 30 and thus connected in an electrically conductive manner to a surface metallization of the PTC element 30, which can be applied as a layer by means of PVD or CVD. The contact plates 38 can also only be placed on the PTC element 30. Each contact sheet 38 forms a contact surface 40 which rests in an electrically conductive manner on the main side surface 32 of the PTC element 30, a contact tongue 42 protruding beyond the PTC element 30 on one side and a latching tongue 44 protruding on the opposite side, hereinafter referred to as the underside out. In the present case, the contact surface 40 is provided congruently with the main side surface 32 of the PTC element 30. The insulating layer 34 lies on the side facing away from the PTC element 30 on the contact sheet 38 and covers it.

The PTC element 30 is received in a frame 46 which for this purpose has a frame opening 48 which is delimited by longitudinal spars 50 and transverse spars 52, 54. The lower transverse bar 54 has two locking openings 56 for receiving the locking tongues 44. The upper transverse bar 52 is formed in one piece with a lead-through element base 58 which, together with a lead-through segment cover 60, forms a type of plug over which a stop collar 61 projects. This stop collar 61 is surmounted by half-shells 62 formed by the frame 46, from which pins 64 protrude. Corresponding to this, the leadthrough segment cover 60 has bores 66 and half-shells 68 aligned with these.

For assembly, one of the contact plates 38 is first inserted with its contact tongue 44 into the half-shell 62. The pin 64 is in this case through a bores cut out on the contact tongue 44 carried out. The latching tongue 44 of the contact plate 38 is introduced into the associated locking opening 56. Connected in this way, the frame 46 has a base formed by the contact plate 38 on which the PTC element 30 is placed. The further contact sheet 38 is then inserted into the other of the two half-shells 62 in the manner described above and placed on the main side surface 32 of the PTC element 30.

The lead-through segment cover 60 is then applied so that the pins 64 are inserted into the bores 66 and the half-shells 68 of the cover 60 complete the half-shells 62 of the base 58. Thereafter, the respective contact tongues 42 are accommodated in an insulating manner in a feed-through channel 70 formed by the half-shells 62, 68 and extended beyond the frame 46 (cf. Figure 4 ). The pins 64 can then be heat staked to secure the base 58 and cover 60 together.

The structural unit produced in this way is covered with insulating layer 34. For this purpose, the plastic film forming the insulating layer 34 is folded over around the lower cross member 54 at the lower end of the frame, so that parallel legs are produced which are each formed by the uniform film and form the insulating layers 34.

The unit produced in this way is placed in a housing 72, which in the present case is formed from sheet metal by deep drawing and is provided with a single opening 74, the area of the housing 72 opposite the opening 74 being closed and provided with a retaining rib 76 which is connected in a the bottom 24 of the heater housing 2 recessed receiving groove for positioning the PTC heating element 22 in the heater housing 2 cooperates. The preassembled unit is introduced into a receiving space 78 of the deep-drawn part 72 through the opening 74. At the end of the introduction movement, the stop collar 61 strikes the edge of the opening 74, whereby the installation position of the frame 46 and thus the components of the PTC heating element 22 held by the frame 46 and placed around the frame 46 is predetermined.

Below the opening 74, the deep-drawn part 72 forms a retaining edge 80 which runs parallel to the edge of the opening 74 around the deep-drawn part 72 and between it and the opening 74 forms a collar 82 which forms a contact surface for a sealing element 84. The sealing element 84 is made of a flexible plastic, for example TPE or silicone, and has passage openings 86 for the half-shells 62, 68 connected to one another. The sealing element 84 can be produced separately and joined to the frame 46 and the deep-drawn part 72. Alternatively, it is also possible to connect the sealing element 84 to the frame 46 and the deep-drawn part 72 by insert molding.

In any case, the sealing element 84 is supported on the retaining edge 80, which is formed by the deep-drawn part 72 itself and is formed by deep-drawing the sheet metal material. All of the contours and projections provided on the deep-drawn part 72 are realized by deep-drawing and are the result of the metal sheet metal forming process. Only the opening 74 is formed by cutting off the excess sheet metal and optionally deburring it.

As the Figure 4 As illustrated, the contact tongues 44 protrude beyond the free ends of the joined half-shells 62, 68 and can be used as male plug-in elements of a plug-in connection to the PTC heating element 22. The sealing element 84 is located at a distance from the end face of the joined half-shells 62, 68.

The economical introduction of the above-mentioned elements into the receiving space 78 means that initially the insulating layers 34 do not bear against the associated inner surfaces of the receiving space 78 in a sufficiently thermally conductive manner, which the Figures 5 and 6 clarify. Thus, after the components have been assembled, the deep-drawn part 72 is reshaped in the region of its longitudinal edges 88. For this purpose, the deep-drawn part 72 is introduced into a die 90 with an upper part 92 and a lower part 94, which are basically identical in shape.

Figure 9 It can be seen that the two parts 92, 94 each form a deforming edge 96 which is placed against the outer surface of the deep-drawn part 72. The point of application of the forming edge 96 lies laterally in the sectional view next to the transverse extension of the PTC element 30 and the associated contact plates 40. The forming edge 96 engages in a free space between the associated longitudinal spar 50 and the PTC element 30 or the contact surface 40 is left free and is only bridged by the insulating layer 34, which at least partially projects beyond the respective longitudinal spar 50.

The deep-drawn part 72 is thus formed only in the area of its longitudinal edges 88. The curvature of the longitudinal edges 88 of the deep-drawn part 72 produced by deep-drawing, initially basically semicircular-shaped by deep-drawing, are bent more inward, as a result of which the inner surfaces of the deep-drawn part extending parallel to the main side surfaces 32 are placed under pretension against the surfaces of the insulating layers 34.

It can be seen that the die 90 grips the respective longitudinal edges 88 both in the direction of movement of the two parts 92, 94 and on the outside of the deep-drawn part 72. Thus, the deep-drawn part 72 inserted into the die 90 touches with its outer sides defined by the longitudinal edges 88 the die 90. The metallic material of the deep-drawn part 72 can accordingly only be formed in the direction of the PTC element 30.

The deformation edge 96 does not act directly against the PTC element 30, so that damage to it during deformation is largely avoided. In addition, the reshaping results in an elastic pre-tension, which results in reliable heat dissipation through good heat conduction from the PTC element 30 through the contact plates 40 and the insulating layer 34 to the inner surface of the deep-drawn part 62 and through this through heat conduction to the outside.

It can be seen that the deep-drawn part 72 is convex with its main side surface. An inner surface 98 extends flatly towards the main side surface 32 of the PTC element 30, whereas the outer side of the deep-drawn part 72 opposite the main side surface 32 is convex. Accordingly, the deep-drawn part 72 in a cross-sectional view in the middle of the inner surface 98 has a greater thickness than at the edge of the inner surface 98. This configuration improves the pretension and strength of the deep-drawn part 72 for applying an external contact pressure to the elements of the PTC heating element mounted in the receiving space 78 22nd

The flat inner surface 98 of the deep-drawn part 72 merges at the edge into a basically circular segment-shaped cavity. The aforementioned deformation of the deep-drawn part 72 takes place only in the area of this cavity. In the Figure 6 The still open C-shaped claw formed by the cavity is after the forming and in Figure 8 clearly more closed. In other words, the diameter of each cavity of the deep-drawn part 72 provided on the longitudinal edges of the deep-drawn part 72 is reduced by the forming processing, as a result of which the opposing inner surfaces 98 are placed against one another and under pretension against the insulating layer 34.

Specifically, a deformation segment 99 is formed by the housing between an outer longitudinal edge 97 and the inner surface 98. This deformation segment 99 is plastically deformed in the direction of the receiving space 78. In the embodiment shown, four such deformation segments 99 are provided. On the top as well as on the bottom according to Figure 8 two deformation segments 99 are provided between the inner surface 98 and the outer longitudinal edge 97. It is sufficient, however, for the preloaded contact of the inner surfaces 98 against the PTC element 30 to merely provide appropriate deformation segments 99 on the upper side, for example, and to plastically deform them in order to introduce an internal preload force into the housing. It does not matter whether the housing is manufactured by deep drawing or otherwise. When the deformation segments 99 are deformed, the outer longitudinal edge 97 remains undeformed in the present case.

Like comparing the Figures 5 or 6 with the Figures 7 8 and 8, the inner surface 98 of the deep-drawn part 62 lies down after the deformation according to FIG Figure 9 flush with the insulating layer 34.

The Figure 2 illustrates the electrical connection of the PTC heating elements 22. For the electrical connection, metal sheets are provided as busbars 100, 102, 104 in the connection chamber 18, which have contact projections 106 formed by punching and bending, which rest against the contact tongues 42 under elastic pretension and these to contact. The contact projections 106 protrude into receiving openings 108 which are recessed in the sheet metal strips of the busbars 100, 102, 104. In the same way, connecting tongues identified with reference numeral 110 are connected, which are in contact with an equipped printed circuit board that is received in a control housing 112. The connection of the busbar 102 takes place directly via the connecting tongue 110, whereas the connection of the busbars 100, 102 is made via a power transistor 114 that is contacted with punched leads 116 that are electrically connected to the associated connecting tongues 110.

List of reference symbols

2

Heater housing

4th

Housing pan element

6th

Inlet port

8th

Outlet port

10

Inlet opening

12

Outlet opening

14th

Circulation chamber

16

partition wall

18th

Connection chamber

20th

female plug-in element receptacle

22nd

PTC heating element

24

ground

30th

PTC element

32

Main face

34

Insulating layer

38

Contact sheet

40

Contact area

42

Contact tongue

44

Locking tongue

46

frame

48

Frame opening

50

Longitudinal spar

52

upper cross member

54

lower cross bar

56

Locking opening

58

Feedthrough element base

60

Feed-through element cover

61

Stop collar

62

Half shell

64

pen

66

drilling

68

Half shell

70

Feed-through channel

72

Deep-drawn part

74

opening

76

Retaining rib

78

Recording room

80

Retaining edge

82

collar

84

Sealing element

86

Passage opening

88

Longitudinal edge

90

Die

92

Top

94

Lower part

96

Forming edge

97

outer longitudinal edge

98

Inner surface

99

Deformation segment

100

Busbar

102

Busbar

104

Busbar

106

Contact advantage

108

Receiving opening

110

Connection tongue

112

Control housing

114

Power transistor

116

Feeder

118

Connector housing power current

120

Connector housing control signals

Claims (15)

PTC heating element (22) for an electrical heating device, with a housing (72) containing at least one PTC element (30), conductor tracks (38) electrically connected to the PTC element (30) and thermally conductive to the PTC element ( 30) inserts adjacent insulating layers (34) as a unit and is surmounted by contact tongues (42) which are electrically conductively connected to the conductor tracks (38) with different polarity in order to energize the PTC element (30), the housing having a PTC Element (30), the conductor tracks (40) and the insulating layers (38) receiving the receiving space (78), characterized in that the receiving space (78) in a cross-sectional view through two opposite and the PTC element (30) overlapping flat inner surfaces (88), deformation segments (99) adjoining the inner surfaces (98) and outer longitudinal edges (88) of the housing (72), the deformation segments (99) in a cross-sectional view between one of the inner surfaces (98) and the associated outer longitudinal edge (88) are provided, the deformation segments (99) being plastically deformed in the direction of the receiving space and with respect to the inner surfaces and the outer longitudinal edges of the housing (72). PTC heating element according to Claim 1, characterized in that the housing (72) has at least one reinforcement (80) which holds at least two of the PTC element (30), conductor track (40) and insulating layer (38) under prestress in the housing ( 72) holds against each other. PTC heating element according to claim 2, characterized in that the reinforcement (80) is formed by a spherical configuration of opposite main side walls of the housing (72), the inner surfaces (88) of which are flat in a cross-sectional view of the housing (72) and on the PTC -Element (30) and which are thicker in the middle of the PTC element (30) than at the edge of the PTC element (30). PTC heating element according to one of the preceding claims, characterized by a ground connection tongue (76) electrically connected to the housing (72). PTC heating element according to one of the preceding claims, characterized by a sealing element (84) made of a flexible plastic which seals an opening (74) in the housing (72) and is protruded by the contact tongues (42). PTC heating element according to Claim 5, characterized in that the sealing element (84) projects beyond the housing (72) in the direction of the longitudinal extension of the contact tongues (42). PTC heating element according to Claim 5 or 6, characterized in that the housing (72) forms a retaining edge (80) holding the sealing element (84). PTC heating element according to one of the preceding claims, characterized by a lead- through element (58, 60) made of an electrically insulating material which is inserted like a plug into a free end of the housing (72) protruding by the contact tongues (42) and lead-through channels (70) for the contact tongues (42). PTC heating element according to one of the preceding claims, characterized in that the housing is a deep-drawn part (72). PTC heating element according to Claim 9, characterized by a retaining rib (76) provided opposite the contact tongues (42) and formed by the deep-drawn part (72). Electrical heating device with at least one PTC heating element (22) arranged in a circulation chamber (14) with a housing (72), the at least one PTC element (30), conductor tracks (38) electrically connected to the PTC element (30) and thermally conductive insulation layers (34) against the PTC element (30) are inserted as a unit and overlooked by contact tongues (42) which are electrically conductively connected to the conductor tracks (38) with different polarity to energize the PTC element (30),
characterized,
that the PTC heating element (22) is designed according to one of claims 1 to 10. A method for producing a PTC heating element (22) for an electrical heating device, having a housing, the at least one PTC element (30), conductor tracks (38) electrically connected to the PTC element (30) and thermally conductive to the PTC element (38) inserts adjacent insulating layers (34) as a unit and is surmounted by contact tongues (42) which are electrically conductively connected to the conductor tracks (38) in order to energize the PTC element (30) with different polarity, in which the PTC element (30), the conductor track (38) and the insulating layers (34) are introduced through an opening (74) in the housing (72) into a receiving space (78) formed by the housing (72) and the housing (72) through to edge areas deformation forces acting on the housing (72) are transformed so that opposing inner surfaces of the housing (72) are placed against the insulating layers (34). Method according to Claim 12, characterized in that the deformation forces act exclusively on an edge of the housing (72) which lies outside a projection surface of main side surfaces of the PTC element to be placed against the insulating layers on an inner surface (98) of the housing (72). Method according to claim 12 or 14, characterized in that the forming forces are applied through a die (90) with upper and lower part (92, 94), the shaped surfaces (96) of which with the outside of the housing (72) outside the PTC element ( 30) cooperate and that in the die (90) the opposite longitudinal edges of the housing (72) in the direction of movement of the die are enclosed on the top and bottom and at right angles thereto. Method according to one of Claims 12 to 14, characterized in that the housing (72) is formed by deep drawing.

Images