Electric heating device

Abstract

The invention relates to an electric heating device, in particular for motor vehicles, which has a first housing part surrounding a first circulation chamber and a second housing part surrounding a second circulation chamber, wherein the first circulation chamber and the second circulation chamber abut against each other. The compact and easy-to-produce electric heating device according to the invention is characterized in that the housing parts abut against each other when a PTC heating device is inserted, the PTC heating device comprising: a first cover element covering the first circulation chamber of the first housing part; a second cover element covering the second circulation chamber of the second housing part; and at least one PTC element arranged between the first cover element and the second cover element, in each case a field electrode being arranged on the PTC element on the inner side of the respective cover element, the field electrode being in conductive contact with the PTC element.

Description

Technical Field

[0001] The invention relates to an electric heating device. In particular, the invention relates to an electric heating device for a motor vehicle, the electric heating device having a first housing part surrounding a first circulation chamber and a second housing part surrounding a second circulation chamber, wherein the two circulation chambers abut against 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. Background Art

[0002] In the heating device known from EP 2 440 004 A1, each circulation chamber is formed by a metal housing into which circumferentially closed heating fins protrude, each forming a receiving pocket. A PTC heating device is arranged in the corresponding receiving pocket, which has a PTC element energized with different polarities, which generates heat in the pocket by energizing, the heat passes through the pocket by thermal conduction and into the circulation chamber, and the heat is dissipated in the circulation chamber. The heat is accordingly dissipated to the outside of the pocket by the fluid to be heated.

[0003] In the prior art according to EP 2 440 004 A1, there is a sealing plate between the housing parts arranged opposite each other, which seals the two housing parts from each other, but the sealing plate is provided with a hole so that the individual circulation chambers can be connected through the hole. The inlet and outlet connectors for the fluid to be heated are arranged on one end face.

[0004] Electric heating devices, in particular for motor vehicles, must be constructed to withstand vibrations. In addition, they must be compactly constructed. The electric heating device must be lightweight. It must operate without interference. Due to the self-regulating properties of the PTC element, it is also necessary that the PTC element be well contacted electrically so that the power current can be introduced into the PTC element with a high degree of reliability while ensuring good dissipation of the heat generated by the PTC element into the circulation chamber. Summary of the invention

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

[0006] In view of this, the present invention provides an electric heating device having the features of claim 1. In the electric heating device, a PTC heating device is arranged between two housing parts. The housing parts are abutted when the PTC heating device is inserted. Therefore, the heating unit of the electric heating device is located between the two housing parts. These housing parts are usually configured in the form of a box, and the open upper side of the corresponding box is in sealing contact with the PTC heating device. Therefore, the PTC heating device covers the first circulation chamber of the first housing part and the second circulation chamber of the second housing part. To this end, the PTC heating device has a first cover element and a second cover element, respectively. At least one PTC element is arranged between the two cover elements. The PTC element between the two cover elements is energized. While the circulation chamber is directly closed by the outer surface of the upper side of the cover element that is wetted or coated with the fluid to be heated, the PTC element is located on the opposite inner surface of the corresponding cover element. Field electrodes are respectively arranged inside the first cover element and the second cover element, and the field electrodes are in conductive contact with the PTC element.

[0007] The two cover elements are located between the two housing parts as parallel layers. The two housing parts usually directly abut the cover elements. In this sense, direct abutment is also abutment in the case of inserting a seal. This abutment is preferred because on the one hand the corresponding circulation chamber abuts the associated cover element in a fluid-tight manner. In addition, the sealing element can also be used as a reservoir for compressive force, for example, in the case of preloading the cover element, to apply a heat sink element, which is accommodated in the circulation chamber and is in conductive contact with the PTC element, and the heat sink element is preferably located between two adjacent PTC elements. Each PTC element is located above a flow channel, which is laterally bounded by the heat sink element, bounded by the base on the bottom side, and bounded by the cover element with the PTC element at the top. A (preferably multiple) PTC element is provided between the two cover elements extending in parallel. The field electrodes of the corresponding PTC elements are usually suitable for the size of the PTC element. The various field electrodes can be connected in series. For this purpose, each cover element has a strip conductor, which usually directly connects the adjacent field electrodes on a single cover element. Typically, one of the cover elements is assigned to the first polarity, and the other cover element is assigned to the second polarity to energize the PTC element. Therefore, the PTC element can be energized by the corresponding cover element. The cover element can be made of or formed by an insulating material, such as a ceramic plate, in particular an aluminum oxide plate. A metallization layer is usually applied to the inner side of such a plate, which forms a field electrode. The metallization layer can be formed by sputtering, printing or vapor deposition. Alternatively, the cover element can be formed by a metal sheet provided with a non-conductive layer recessed in the region of the field electrode. Therefore, the metal sheet forms a busbar for energizing one or more PTC elements. The metal sheet can be provided with a non-conductive layer on the outside of the field electrode to improve the gap and creepage distance between the cover elements of different polarities. Typically, the metal sheet is completely surrounded by a non-conductive layer inside the housing component away from the field electrode.

[0008] In case the cover element is formed by a metal sheet, the surface of the cover element covering the circulation chamber is usually configured to be non-conductive. Thus, the metal sheet can be covered with a non-conductive foil or coated with a non-conductive layer, such as a ceramic layer. Preferably, the cover element is configured so that the fluid to be heated and located in the circulation chamber does not directly wet the conductive elements of the cover element.

[0009] According to a preferred improvement of the invention, each housing part is formed by a plastic groove, which has at least one connection piece, which leads to the circulation chamber and protrudes from the plastic groove. Preferably, the housing parts are formed identically. Therefore, the same parts can be used to form the two housing parts of the invention, which reduces production costs.

[0010] It is further preferred that each housing part has only a single connector and the two circulation chambers are fluidically interconnected by a hole through the PTC heating device. In this way, the advantages known from EP 2 440 004 A1 in this respect can be used, i.e., a compact electric heating device can be produced that requires only a few components. It is understood that the hole penetrating the PTC device is sealed relative to the interior of the PTC device so that the medium to be heated cannot reach the PTC element and the field electrode. The hole can be surrounded between the first cover element and the second cover element, for example, by an insulating block or a sealing element, which is clamped, glued or arranged between the two cover elements.

[0011] According to another preferred configuration, a heat sink element is arranged between the base of the first housing part or the second housing part and the PTC heating device, and the heat sink element is connected to at least one PTC element in a heat-conducting manner, thereby improving the heat dissipation result of the medium to be heated in the trough-shaped housing part. This measure is particularly advantageous when the housing part is formed as a trough made of plastic.

[0012] The heat sink element is made of a material with good thermal conductivity. It can be made of ceramic or metal. The heat sink element can be formed as a simple metal disk. The heat sink element can also be formed with openings or as a relatively complex heat sink element, which can be formed from a bent metal sheet or an extruded profile, in particular from aluminum. The heat sink element is usually supported on a base of the associated housing part and a cover element that covers the housing part as a separate component. The fixing can be done by gluing or positive locking.

[0013] Preferably, the heat sink element is preloaded against a point of the cover element between two PTC elements. This reliably achieves good heat dissipation of the heat generated by the PTC elements. The heat sink element can be elastically preloaded against the cover element and connected to the PTC element in a thermally conductive manner. The heat sink element can also be connected to a side wall that closes the groove in the circumferential direction, preferably so that the flow path is located between the heat sink element and the adjacent side wall. Therefore, the heat sink element preferably protrudes from the base and the cover element and the adjacent side wall so that the flow can only pass through the end side of the heat sink element opposite to the side wall.

[0014] Preferably, a plurality of heat sink elements are arranged so that one heat sink element is behind another heat sink element and staggered with each other in the extension direction of the corresponding circulation chamber, and are therefore preferably attached to the side wall of the corresponding housing laterally, and preferably a tortuous flow channel is formed by the heat sink elements. Therefore, the fluid flowing through the circulation chamber in the extension direction is deflected by the corresponding heat sink element and is guided through the circulation chamber in a tortuous manner, with the result that the surface of the heat sink element covered by the fluid to be heated is increased. The extension direction of the housing can be the longitudinal or width direction of the housing. The height direction separates the base from the cover element by a certain distance. Usually, the above-mentioned connector is provided on one end face of the housing component, and a hole penetrating the PTC heating device is provided near the end face opposite to the above-mentioned connector, which transfers the flow from one housing component to another housing component.

[0015] As another measure to improve the gap and creepage distance between field electrodes of different polarities, it is proposed according to another preferred improvement scheme that the edge of the field electrode protruding beyond the PTC element is covered by a weld bead of insulating material protruding beyond the field electrode, so that the PTC element is rigidly held between the relative weld beads. Such a weld bead is usually associated with two field electrodes to form a PTC element each. The weld bead also provides rigid retention of the PTC element on the electrode metal sheet. Individual PTC elements can only move upward to the weld bead. Therefore, the PTC element can only be sandwiched between the field electrodes and cannot be directly connected to the cover element in other ways. Preferably, the weld bead is formed by an insulating adhesive material. Therefore, the weld bead can also be used to completely or partially seal in the PTC element with its circumferential edge. The circumferential edge extends at right angles to the cover element and extends between field electrodes of different polarities. As long as the field electrode has a bottom area smaller than that of the PTC element, the corresponding weld bead is directly bonded to the edge of the cover element and the PTC element.

[0016] The weld bead may, for example, consist of a silicone adhesive which bonds to the inner surface of the cover element and / or to the field electrode and / or to the edge of the PTC element or completely seals the PTC element.

[0017] As mentioned above, a compressible seal is preferably provided between the two housing parts. The compressible seal stores a certain amount of compressive force, which applies the heat sink element to the part of the cover element opposite to the PTC element, especially under preload. The housing parts usually have openings located in a single plane. The planes of the two openings of the first housing part and the second housing part preferably extend parallel to each other. Each opening is preferably provided with a compressible seal, on which the associated cover element abuts. Another compressible sealing element may be provided between the opposing cover elements. Typically, the interior between the two cover elements is sealed from the exterior by a compressible substance close to the edge of the cover element and connecting the two cover elements.

[0018] Preferably, each cover element has at least one strip conductor leading to the respective field electrode. One end of the strip conductor is preferably exposed when the associated part of the cover element is located outside the associated housing part to form a contact. The power current is usually introduced here. The associated part of the cover element is usually located outside the above-mentioned compressible seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] More details and advantages of the present invention can be obtained through the following description of the embodiments in conjunction with the accompanying drawings.

[0020] Figure 1 An exploded view of the embodiment is shown in side view;

[0021] Figure 2 A top view of a housing component of an embodiment is shown; and

[0022] Figure 3 A cross-sectional view showing a PTC heating device of an embodiment is shown. DETAILED DESCRIPTION

[0023] Figure 1 Two housing parts 2, 4 of identical design are shown, wherein the housing part denoted by reference numeral 2 is referred to as the first housing part 2 and the other housing part shown below it is referred to as the second housing part 4. The individual housing parts 2, 4 are designed as grooves and have openings facing each other. Figure 1 The illustration allows the second housing part 4 to be seen. A plurality of heat sink elements 6 are arranged inside the groove-shaped housing parts 2, 4. The meandering arrangement of the heat sink elements 6 can be particularly Figure 2 The fin elements 6 are supported on a base 8 of the housing parts 2, 4 and are connected to the base 8 in such a way that no passage of the fluid to be heated is possible between the respective fin element 6 and the base 8. The fin elements 6 are arranged offset from one another in a main extension direction corresponding to the longitudinal direction indicated by the reference numeral 10. The free ends of the fin elements 6 are arranged in a width direction (i.e. transversely to the longitudinal direction according to Figure 2 The two connecting pieces 10 of the housing 4 overlap each other to a large extent (in the direction of the extension direction 10 of the housing 4). A tortuous flow channel 12 is thus formed. The fluid entering the corresponding housing parts 2, 4 through the connecting piece denoted by the reference numeral 14 flows against the first heat sink element 6 in the flow direction and is deflected. The fluid must pass through the end side 16 of the heat sink element in order to reach between the first heat sink element and the second heat sink element 6. A through hole 20 is provided on the opposite side wall 18 of the housing part 4. At the end of the tortuous flow channel 12 opposite to the connecting piece 14, there is a hole denoted by the reference numeral 22, which is recessed in the PTC heating device 24. There, the fluid flow is transmitted from the second housing part 4 to the first housing part 2.

[0024] The PTC heating device 24 and its components can be used in particular Figure 1 . The PTC heating device 24 has a first cover element 26 and a second cover element 28. The outer surface of the first cover element 26 covering the first housing part 2 is provided with an insulating layer or is constructed in an insulating manner. Thus, for example, the first cover element 26 and the second cover element 28 can be formed by a ceramic plate. A plurality of field electrodes 30 are arranged on the opposite inner surfaces of the respective cover elements 26, 28. In the present case, these field electrodes are made by applying an electrically conductive material to a ceramic material. The different field electrodes 30 of the individual cover elements 26, 28 are connected in series via strip conductors 32. The strip conductors 32 end at a portion 34 of the associated cover element. There, the strip conductors 32 are exposed at the edge. The corresponding portion 34 will regularly protrude beyond the housing parts 2, 4 so that an electrical contact of the strip conductor 32 can be made at this portion.

[0025] Each field electrode 30 is provided with a PTC element 36 which can be contacted via the field electrode 30 and to which a power current can be applied. Figure 1 The inner side which cannot be seen in the drawing is formed in a corresponding manner. The two cover elements 26, 28 are placed against each other with the PTC element 36 inserted. The compressible seal indicated by the reference numeral 38 is placed on the edge of the corresponding housing part 2, 4. The two housing parts 2, 4 are applied against each other with the PTC heating element 24 inserted. The clamping pin passes through the through hole 20, which pre-tightens the two housing parts 1, 2 against each other. This pre-tightening pressure acts not only on the edge of the outer wall of the housing parts 2, 4, but also on the free end of the corresponding heat sink element 6. The heat sink elements 6 each rest on the cover elements 26, 28 at a point between the PTC elements 36. Therefore, a certain pre-tightening force used to pre-tighten the heat sink element 6 between the base 8 and the associated cover elements 26, 28 is also transmitted to the PTC element 36 by the pre-tightening of the cover elements 26, 28 formed by the metal sheet. The PTC elements 36 are thus preloaded against the field electrodes 30, which improves the introduction of power current into the respective PTC elements 36 and the dissipation of heat from the respective PTC elements 36. This results in good heat dissipation from the PTC heating devices 24 into the respective circulation chambers, which are located in the Figure 1 and 2 The circulation chamber 42 is indicated by reference numeral 42. The circulation chamber 42 is kept fluid-tight by the seal 38.

[0026] Figure 3A cross-section of a PTC heating element 24 is shown. It is evident that the PTC element 36 is clamped between the two cover elements 26, 28 and is in contact with an associated field electrode 30, the free edges of which are each covered by a weld bead 44 which protrudes beyond the field electrode 30 and also covers a certain height of the PTC element 36. The weld bead 44 fixes the PTC element 36 rigidly to the field electrode 30.

[0027] The embodiment is easy to manufacture. The two housing parts 2 and 4 are constructed identically. A good heat dissipation effect is produced, not only because the circulation chambers 42 are each equipped with a plurality of heat sink elements 6, which dissipate the heat of the PTC element 36 from the PTC heating device 24 and transfer the dissipated heat to the corresponding circulation chambers 42. The tortuous flow path allows the heat to be dissipated from the corresponding heat sink elements 6 to the fluid to be heated as best as possible. The fluid is usually a liquid fluid, especially water, which is usually circulated in the heating circuit of a motor vehicle. The preferred application of the heating device according to the present invention is especially electric vehicles. The above-mentioned electric heating device can be used in particular for heating the interior of the vehicle. However, other electrical or electronic components in the electric vehicle can also be heated with the electric heating device.

[0028] Reference numerals list

[0029] 2 First housing part

[0030] 4 Second housing part

[0031] 6 Heat sink components

[0032] 8 Base

[0033] 10 Extension direction

[0034] 12 Flow channel

[0035] 14 Connectors

[0036] 16 End side

[0037] 18 Sidewall

[0038] 20 Through Holes

[0039] 22 holes

[0040] 24 PTC heating device

[0041] 26 first cover element

[0042] 28 Second cover element

[0043] 30 Field electrodes

[0044] 32 Strip conductor

[0045] 34 parts

[0046] 36 PTC components

[0047] 38 Seals

[0048] 40 On the outer side of the cover element, opposite to the PTC element

[0049] 42 Circulation Chamber

[0050] 44 weld passes

Claims

1. An electric heating device for a motor vehicle, the electric heating device having a first housing part surrounding a first circulation chamber and a second housing part surrounding a second circulation chamber, wherein: The first circulation chamber and the second circulation chamber abut against each other, The housing parts abut against each other when a PTC heating device is inserted therein, and the PTC heating device comprises: a first cover element, the first cover element being made of an insulating material and covering the first circulation chamber of the first housing component; a second cover element made of an insulating material and covering the second circulation chamber of the second housing member; and A plurality of PTC elements, which are arranged between the first cover element and the second cover element, characterized in that in each case a plurality of field electrodes are arranged on the inner side of the respective cover element, wherein each of the plurality of field electrodes is in conductive contact with a corresponding one of the plurality of PTC elements, and each of the first cover element and the second cover element has a strip conductor which is configured to connect in series the field electrodes arranged on the cover elements.

2. The electric heating device according to claim 1, wherein: The housing parts are each formed by a plastic groove, which includes at least one connection piece which opens into at least one of the first circulation chamber and the second circulation chamber and protrudes from the plastic groove.

3. The electric heating device according to claim 2, wherein: Each housing part has only one connection piece, and the two circulation chambers are fluidically connected to one another via a bore that penetrates the PTC heating device.

4. The electric heating device according to claim 1, wherein: A heat sink element is arranged between the base of the first housing part or the second housing part and the PTC heating device, and is connected to at least one of the PTC elements of the cover element in a heat-conducting manner via an associated cover element.

5. The electric heating device according to claim 1, wherein: A plurality of heat sink elements are arranged one behind another and are offset from one another in the extension direction of the corresponding circulation chamber, wherein the heat sink elements are connected to at least one of the PTC elements of the cover element in a heat-conducting manner via an associated cover element, and wherein the heat sink elements are transversely attached to the side walls of the corresponding housing component and are dimensioned such that a tortuous flow channel is formed by the heat sink elements.

6. The electric heating device according to claim 1, wherein: The cover element is formed by an aluminium oxide plate, and wherein the field electrode is formed by a metallization layer applied to the aluminium oxide plate.

7. The electric heating device according to claim 1, wherein: The cover element is formed by a metal sheet which is provided with a non-conductive layer which is recessed in the region of the field electrode.

8. The electric heating device according to claim 1, wherein: At least one edge of the field electrode protruding beyond the PTC element is covered by a bead of insulating material, which protrudes beyond the field electrode such that the PTC element is arranged between opposing bead in a form-fitting manner between two cover elements.

9. The electric heating device according to claim 1, wherein: The two housing parts are brought into tight contact with one another with the interposition of at least one compressible seal.

10. The electric heating device according to claim 1, wherein: A compressible seal is provided in each case between one of the housing parts and the associated cover element, and wherein the two housing parts are preloaded against one another with the insertion of the compressible seal, so that the heat sink element is clamped between the field electrode and the base of the respective housing part.

11. The electric heating device according to claim 1, wherein: One end of the strip conductor is exposed with the associated portion of the cover element located outside the associated housing component for making contact.

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