Electric heating device

Abstract

An electric heating device, particularly for a motor vehicle, comprising a first housing part (2) surrounding a first circulation chamber (42) and a second housing part (4) surrounding a second circulation chamber (42), wherein the first and second circulation chambers (42) are in contact with each other, wherein the housing parts (2, 4) are in contact with each other with an interposed PTC heating device (24) comprising a first cover element (26) covering the first circulation chamber (42) of the first housing part (2) and a second cover element (28) covering the second circulation chamber (42) of the second housing part (4), and at least one PTC element (36) provided between the first and second cover elements (26, 28), characterized in that an electrically conductive element is provided on the inside of each of the respective cover elements (26, 28) for the PTC element (36). The electrode field (30) is provided for the PTC element (36) that is contacted.wherein the cover element (26, 28) is formed by an electrically insulating material and the electrode field (30) by a metallization applied to the electrically insulating material, or the cover element (26, 28) is formed by a sheet provided with a non-electrically conductive layer which is recessed in the area of ​​the electrode field (30).

Description

[0001] The present invention relates to an electric heating device. In particular, the present invention relates to an electric heating device for a motor vehicle comprising a first housing part surrounding a first circulation chamber and a second housing part surrounding a second circulation chamber, wherein the two circulation chambers are in a position abutting each other. Such an electric heating device is known from EP 2 440 004 A1. A similar electric heating device is known from EP 2 797 382 B1.

[0002] In the heating device known from EP 2 440 004 A1, the respective circulation chambers are formed from a metallic housing into which fully enclosed heating fins project, each forming a receiving pocket. PTC heating elements are provided in the corresponding receiving pockets. These elements comprise a PTC element energized with opposite polarity, which generates heat within the pocket. This heat is conducted through the pocket and into the circulation chamber, where it is released. The heat is then dissipated on the outside of the pocket by the fluid being heated.

[0003] According to the prior art EP 2 440 004 A1, a sealing plate is located between the opposing housing parts. This plate seals the two housing parts against each other but has a hole allowing communication between the respective circulation chambers. Inlet and outlet ports for the fluid to be heated are provided on one of the end faces.

[0004] Electric heating devices, especially for motor vehicles, must be vibration-resistant. Furthermore, they must be compact and lightweight. They must operate reliably. Due to the self-regulating properties of PTC elements, good electrical contact is also essential to ensure a reliable power supply and efficient heat dissipation into the circulation chamber.

[0005] The present invention aims to provide an electric heating device of the type mentioned above, which meets the above requirements in an improved manner. In particular, the present invention aims to provide an electric heating device with a simple design. The electric heating device is intended to be suitable for heating liquid media, especially for heating a water circuit within a vehicle.

[0006] In this respect, the present invention provides an electric heating device with the features of claim 1. In this electric heating device, a PTC heating element is provided between the two housing parts. The housing parts rest against each other with this PTC heating element in between. Thus, the heat-generating cell of the electric heating device is located between the two housing parts. These are typically designed in the form of boxes, with the open top of each box sealed against the PTC heating element. The PTC heating element covers the first circulation chamber of the first housing part and the second circulation chamber of the second housing part. For this purpose, the PTC heating element has a first and a second cover element. At least one PTC element is provided between these two cover elements. The PTC element is energized between the two cover elements.While the circulation chamber is directly sealed by the outer surface of the cover element, which is wetted or coated with the fluid to be heated, the PTC element is located on the opposite inner surface of the respective cover element. An electrode array is provided on the inner surface of the first and second cover elements, respectively, which is electrically connected to the PTC element.

[0007] The two cover elements lie in parallel layers between the two housing parts. The two housing parts typically rest directly against the cover elements. Direct contact in this sense also includes contact with an interposed seal. Such a configuration is preferable because, firstly, it creates a fluid-tight seal between the respective circulation chamber and the associated cover element. Furthermore, a sealing element can also be used to store compression force, for example, to apply preload to a ribbed element, which is located in the circulation chamber and electrically connected to the PTC element, against the cover element, preferably between two adjacent PTC elements. The respective PTC elements are located above a flow channel, which is bounded laterally by the ribbed element, below by a base, and above by the cover element with the PTC element.Between the two parallel cover elements, one, preferably several, PTC element(s) are provided. The electrode fields for the respective PTC elements are usually adapted to the size of the PTC elements. Individual electrode fields can be connected in series. For this purpose, each cover element has a conductor track that connects adjacent electrode fields on a single cover element. Typically, one cover element is assigned to a first polarity and the other to a second polarity for energizing the PTC element. Thus, the PTC element can be energized via the respective cover element. The cover element can consist of, or be formed from, an insulating material, for example, a ceramic plate, in particular an aluminum oxide plate. A metallization is usually applied to the inside of such a plate, which forms the electrode field.The metallization can be achieved through sputtering, printing, or vapor deposition. Alternatively, the cover element can be formed by a sheet metal component coated with a non-conductive layer, which is omitted in the area of ​​the electrode field. In this way, the sheet metal component forms the busbar for supplying current to the PTC element(s). Outside the electrode field, the sheet metal component can be coated with an electrically non-conductive layer to improve air and creepage distances between cover elements of different polarities. Typically, within the housing components, the sheet metal component is completely surrounded by the electrically non-conductive layer, except in the area of ​​the electrode fields.

[0008] In the case of a cover element formed from a sheet metal panel, the surface of the cover element that covers the circulation chamber is typically designed to be electrically non-conductive. For example, a sheet metal panel can be coated with an electrically non-conductive film or with an electrically non-conductive layer, such as a ceramic layer. The cover element is preferably designed such that the fluid to be heated, which is located in the circulation chamber, does not directly wet the electrically conductive elements of the cover element.

[0009] According to a preferred embodiment of the present invention, the respective housing parts are each formed by a plastic tray, which has at least one nozzle leading to the circulation chamber and projecting from the plastic tray. The housing parts are preferably identical. This allows identical components to be used to form both housing parts of the present invention, which reduces production costs.

[0010] Furthermore, it is preferable that each of the housing parts has only a single nozzle and that the two circulation chambers are fluidically connected to each other via a hole passing through the PTC heating element. This allows the advantages known from EP 2 440 004 A1 to be utilized, i.e., a compact electrical heating device requiring only a few components. It is understood that the hole passing through the PTC element is sealed from the interior of the PTC element so that the medium to be heated cannot reach the PTC elements and the electrode fields. The hole can, for example, be surrounded between the first and second cover elements by an insulating compound or a sealing element, which is clamped, glued, or positioned between the two cover elements.

[0011] According to a further preferred embodiment, in which a finned element is provided between a base of the first or second housing part and the PTC heating element, and this finned element is thermally connected to at least one of the PTC elements, improved heat transfer to the medium to be heated is achieved within a trough-shaped housing part. Such a measure is particularly advantageous when the housing part is shaped as a trough made of plastic.

[0012] The finned element is made of a material with high thermal conductivity. It can be made of ceramic or metal. The finned element can be a simple metallic disc. It can also be designed with perforations or as a relatively complex radiator element, which may be made of bent sheet metal or extruded profiles, particularly of aluminum. The finned element is typically supported by the base of the associated housing part and by the cover element that protects this housing part, forming a separate component. It can be attached by bonding or a positive fit.

[0013] Preferably, the ribbed element is applied under preload against the point of the cover element located between two PTC elements. This ensures reliable and efficient heat dissipation from the heat generated by the PTC element. The ribbed element can be applied under elastic preload against the cover element and thus thermally connected to the PTC elements. The ribbed element can also connect to a side wall that completely encloses the tank, preferably in such a way that the flow path is routed between the ribbed element and the adjacent side wall. In this way, the ribbed element preferably projects from the bottom, the cover element, and the adjacent side wall in such a way that the flow can only pass through the end face of the ribbed element opposite the side wall.

[0014] Preferably, several rib elements are arranged one behind the other and offset from each other in the direction of extension of the respective circulation chamber, and are preferably attached laterally to the side wall of the respective housing, preferably in such a way that a meandering flow channel is formed by the rib elements. The fluid flowing through the circulation chamber in the direction of extension is accordingly deflected over the respective rib elements and guided through the circulation chamber in a meandering pattern, thereby increasing the surface area of ​​the rib elements swept by the fluid to be heated. The direction of extension of the housing can be longitudinal or transverse. The vertical direction separates the bottom from the cover element.Typically, the aforementioned nozzle is located on one end face of the housing part, and adjacent to the opposite end face is the hole through which the PTC heating device passes, transferring the flow from one housing part to the other housing part.

[0015] As a further measure to improve the air and creepage distances between electrode fields of different polarity, a preferred embodiment proposes that an edge of the electrode field projecting beyond the PTC element be covered by a bead of insulating material. This bead projects beyond the electrode field in such a way that the PTC element is positively engaged between opposing beaded sections. Such beaded sections are typically assigned to each of the two electrode fields, corresponding to one PTC element each. The beaded sections also provide a positive-engagement hold for the PTC element on the electrode plate. The respective PTC element can only be moved up to the beaded section. Thus, the PTC element is merely clamped between the electrode fields and not otherwise directly connected to the covering element. Preferably, the bead is formed from an insulating adhesive material.The bead can also be used to completely or partially seal the PTC element and its surrounding edge. This surrounding edge extends perpendicular to the cover element and between the electrode fields of differing polarity. If the electrode field has a smaller base area than the PTC element, the corresponding bead is adhered directly to the cover element and the edge of the PTC element.

[0016] The bead can, for example, consist of a silicone adhesive that is applied to the inner surface of the cover element and / or the electrode field and / or the edge of the PTC element, or that completely seals the PTC element.

[0017] As mentioned previously, a compressible seal is preferably provided between the two housing parts. This compressible seal stores a certain amount of compression, which in particular applies preload to the rib elements against the point of the cover element opposite the PTC element. The housing parts typically have an opening lying in a single plane. The planes of the two openings of the first and second housing parts preferably run parallel to each other. Each of the openings is preferably provided with a compressible seal against which the associated cover element rests. Another compressible sealing element may be provided between the opposing cover elements. The interior between the two cover elements is usually sealed to the outside by a compressible compound applied close to the edge of the cover elements, which connects both cover elements.

[0018] Preferably, the cover elements each have at least one conductive track leading to the respective electrode field. One end of the conductive track is preferably exposed on the outside of the associated housing part, forming a contact with a corresponding section of the cover element. The power current is typically introduced at this point. This section is usually located outside the aforementioned compressible seal.

[0019] Further details and advantages of the present invention will become apparent from the following description of an exemplary embodiment in conjunction with the drawing. The drawing shows: Fig. 1 an exploded view of the embodiment in a side view; Fig. 2 a top view of a housing part of the exemplary embodiment; and Fig. 3 a sectional view through the PTC heating device of the exemplary embodiment.

[0020] The Fig. Figure 1 shows two identically designed housing parts. 2 , 4 , of which the one with reference mark 2 marked housing part as first housing part 2 and the further housing part shown below as the second housing part 4 is referred to as the respective housing parts. 2 , 4 They are shaped like troughs and have openings opposite each other. The illustration according to Fig. 1 allows a view into the second part of the housing 4 to. Within the trough-shaped housing parts 2 , 4 are several rib elements 6 arranged. The meandering arrangement of the rib elements 6 can be particularly Fig. Remove 2. The rib elements 6 leaned against a ground 8 the housing parts 2 , 4 and are connected to it in such a way that between the respective rib element 6 and the ground8 No passage of fluid to be heated is possible. The rib elements 6 are in the with reference number 10 The main extension direction, which corresponds to the longitudinal direction, is offset from each other. The free ends of the rib elements 6 They overlap in the latitudinal direction, i.e., perpendicular to the direction of extension. 10 according to Fig. 2. considerably. This creates a meandering flow channel. 12 shaped. This is indicated by a reference mark. 14 marked spigot into the respective housing part 2 , 4 The incoming fluid is forced against the first rib element in the direction of flow. 6 flowing towards it and deflected. There must be an end side. 16 of the rib element to pass between the first and the second rib element 6 to get there. Opposite side walls 18 of the housing part 4are equipped with through holes 20 provided. At the end of the meandering flow channel 12 and opposite the stub 14 is with reference mark 22 A hole is indicated, which is in a PTC heating device. 24 It is recessed. There, the fluid flow is diverted by the second housing part. 4 into the first housing part 2 transferred.

[0021] The PTC heating element 24 is with its components in particular Fig. 1. The PTC heating element 24 has a first cover element 26 and a second cover element 28 The first housing part 2 covering outer surface of the first cover element 26 is provided with an insulating layer or is designed to be insulating. This allows the first and second cover elements to be used together. 26 , 28for example, it could be made of a ceramic plate. On the opposing inner surfaces of the respective cover elements. 26 , 28 are a multitude of electrode fields 30 arranged. These are produced in this case by applying an electrically conductive material to the ceramic material. The different electrode fields 30 a single cover element 26 , 28 are via a conductor track 32 connected in series. The conductor track 32 Ending at a section 34 of the associated cover element. The conductor track is located there. 32 Free at the edges. The corresponding section 34 The housing parts are regularly checked. 2 , 4 protrude so that the electrical contact of the conductor track is not possible at that section 32 can be done.

[0022] Regarding the electrode fields 30 These are all PTC elements. 36provided for, which via the electrode fields 30 can be contacted and supplied with power. It goes without saying that the in Fig. 1. Unrecognizable inner side of the first cover 26 is designed accordingly. The two cover elements 26 , 28 are placed under the intermediate layer of PTC elements 36 Placed against each other. One with a reference mark. 38 The marked compressible seal is placed on the edge of the respective housing part. 2 , 4 Placed underneath. With the PTC heating element in between. 24 will the two housing parts 2 , 4 positioned against each other. Through the through holes 20 Tension pins are inserted, which preload the two housing parts 1, 2 against each other. This preload pressure acts not only on the edges of the outer walls of the housing parts. 2 , 4but also against the free ends of the respective rib elements 6 The rib elements 6 They are each positioned against the cover elements. 26 , 28 on, specifically at a point between the PTC elements 36 This also creates a certain preload with which the rib elements 6 between the ground 8 and the associated cover element 26 , 28 are tensioned, via a pre-tensioning of the sheet metal cover elements 26 , 28 on the PTC elements 36 is transferred. This is how the PTC elements are transferred. 36 under bias against the electrode fields 30 This design improves the introduction of power flow into and the extraction of heat from each PTC element 36. This results in good heat dissipation from the PTC heating element. 24 into the respective circulation chambers, which are in Fig. 1 and Fig. 2 with reference numeral 42 are marked. The circulation chambers 42 are through the seals 38 fluid-tight.

[0023] The Fig. Figure 3 shows a sectional view of the PTC heating element. 24 The PTC element is clearly visible. 36 between the two cover elements 26 , 28 clamped and contacts the associated electrode field 30 Its free edges are each bordered with a bead. 44 covered, which covers the electrode field 30 exceeds and also a certain height of the PTC element 36 covered. By this bulge 44 is the PTC element 36 positively locking on the electrode field 30 secured.

[0024] This embodiment is easy to manufacture. The two housing parts 2 , 4They are identically designed. This results in good heat dissipation, not least because of the circulation chambers. 42 each with a multitude of rib elements 6 are equipped with components that dissipate the heat from the PTC element. 36 from the PTC heating element 24 divert and into the respective circulation chamber 42 transfer. The meandering flow pattern ensures optimal heat dissipation from the respective fin elements. 6The heating element is created within the fluid to be heated. This fluid is typically a liquid, especially water, which usually circulates in the heating circuit of a motor vehicle. Preferred applications of the heating device according to the invention are, in particular, electric vehicles. The electric heating device described above can be used, in particular, to heat the vehicle interior. However, other electrical or electronic components within an electric vehicle can also be heated with the electric heating device. Reference symbol list 2 first housing part 4 second housing part 6 rib element 8 Floor 10. Direction of extension 12 Flow channel 14 stubs 16 End page 18 side wall 20 through holes 22 holes 24 PTC heating element 26 first cover element 28 second cover element 30 electrode field 32 conductor tracks Section 34 36 PTC elements 38 Seal 40. Location opposite the PTC element on the outside of the cover element 42 Circulation chamber 44 bulge QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2440004 A1 [0001, 0002, 0003, 0010] EP 2797382 B1

[0001]

Claims

[1] Electric heating device, in particular for a motor vehicle, comprising a first housing part (2) surrounding a first circulation chamber (42) and a second housing part (4) surrounding a second circulation chamber (42), wherein the first and the second circulation chamber (42) are in contact with each other, characterized by , that the housing parts (2, 4) are in contact with each other with an interposition of a PTC heating device (24), which comprises a first cover element (26) covering the first circulation chamber (42) of the first housing part (2) and a second cover element (28) covering the second circulation chamber (42) of the second housing part (4), and at least one PTC element (36) which is provided between the first and the second cover element (26, 28) and to which an electrode field (30) is provided on the inside of the respective cover elements (26, 28) which is electrically conductively contacted on the PTC element (36). [2] Electric heating device according to claim 1, characterized by , that the housing parts (2, 4) are each formed by a plastic tray which has at least one nozzle (14) leading to one of the circulation chamber (42) and projecting from the plastic tray. [3] Electric heating device according to claim 2, characterized by , that each of the housing parts (2, 4) has only one nozzle (14) and that the two circulation chambers (42) are flow-connected to each other via a hole (22) passing through the PTC heating device (24). [4] Electric heating device according to any one of the preceding claims, characterized by , that a finned element (6) is provided between a base (8) of the first or second housing part (2, 4) and the PTC heating device (24), which is thermally connected via the associated cover element (26, 28) to at least one of the PTC elements (36) of the cover element (26, 28). [5] Electric heating device according to any one of the preceding claims, characterized by , that several rib elements (6) are provided one behind the other and offset from each other in an extension direction (10) of the respective circulation chambers (42) and that the rib elements (6) are attached laterally to a side wall (18) of the respective housing part (2, 4) and are dimensioned such that a meandering flow channel (12) is formed by the rib elements (6). [6] Electric heating device according to any one of the preceding claims, characterized by , that the covering element (26, 28) is formed by an aluminum oxide plate and that the electrode field (30) is formed by a metallization applied to the aluminum oxide plate. [7] Electric heating device according to any one of claims 1 to 5, characterized by, that the cover element (26, 28) is formed by a sheet metal which is provided with a non-electrically conductive layer which is recessed in the area of ​​the electrode field (30). [8] Electric heating device according to any one of the preceding claims, characterized by , that at least one edge of the electrode field (30) projecting beyond the PTC element (36) is covered by a bead (44) made of an insulating material, which projects beyond the electrode field (30) in such a way that the PTC element (36) is provided in a form-fitting manner between the two cover elements (26, 28) between opposing bead (44). [9] Electric heating device according to any one of the preceding claims, characterized by , that the two housing parts (2, 4) are tightly in contact with each other with at least one compressible seal (38) in between. [10] Electric heating device according to any one of the preceding claims, characterized by, that a compressible seal (38) is provided between each of the housing parts (2, 4) and the associated cover element (26, 28) and that the two housing parts (2, 4) are pre-tensioned against each other with the compressible seal (38) in between, such that the rib element (6) is clamped between the electrode field (30) and the bottom (8) of the respective housing part (2, 4). [11] Electric heating device according to any one of the preceding claims, characterized by , that the two cover elements (26, 28) have a conductor track (32) leading to the respective electrode field (30) and that one end of the conductor track (32) with an associated section (34) of the cover element (26, 28) on the outside of the associated housing part (2, 4) is exposed to form a contact.

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