Electric heating device

Abstract

The invention relates to an electric heating device, comprising a control unit having a circuit card with a circuit, the circuit card having a power transistor, the power transistor having a power transistor housing and at least three connection electrodes, a first electrode, a second electrode and a third electrode, at least three coupling electrodes (105, 202) project from the power transistor housing (201) at the same side. According to the invention, the power transistor has an injection-molded encapsulation, the injection-molded encapsulation (207) comprising: a first region (208) in which the injection-molded encapsulation (207) extends the power transistor housing (201) in the direction of the connection electrodes (105, 202) and collectively surrounds the at least three electrodes (203, 204, 205), and a second region (208) in which the injection-molded encapsulation (207) extends the power transistor housing (201) in the direction of the connection electrodes (105, 202) and collectively surrounds the at least three electrodes (203, 204, 205). And a second region (209), in which the injection-molded encapsulation (207) individually surrounds at least one of the three connection electrodes (105, 202), in particular the second electrode (204).

Description

Technical Field

[0001] The invention relates to an electric heating device according to the generic category of the independent patent claims and to a method for producing an electric heating device according to the generic category of the coordinated patent claims. Background Art

[0002] EP 3 115 236 A1 discloses an electric heating device, in particular for a motor vehicle, comprising a heating element and a control unit, wherein the control unit comprises a circuit card with at least one electronic circuit, and wherein the control unit comprises at least one power transistor, which is electrically connected to the at least one electronic circuit, wherein the control unit comprises at least one first metal support, wherein the at least one power transistor is arranged on the at least one first metal support and is connected to the at least one first metal support.

[0003] The new generation of electric heaters operates at voltages up to 1000V or higher, requiring extensive electrical insulation to ensure passenger protection. Furthermore, open surfaces of components carrying electrical potential must maintain minimum clearances from other electrically conductive components, also known as air gaps and creepage distances. Creepage distance is defined as the shortest connection along the surface of a non-conductive component (insulator) between two conductive components, while air gap corresponds to the shortest distance through air between two conductive components. These minimum distances are regulated by various standards, such as IEC 60664, which define minimum air gaps and creepage distances based on voltage requirements and soiling levels. Summary of the Invention

[0004] The object of the present invention is to ensure the operational safety of an electric heating device under difficult environmental conditions, in particular to avoid short circuits during operation and to ensure proper functioning of the heating device.

[0005] The present invention relates to an electric heating device for heating a fluid in a vehicle. The heating device comprises a control unit having a circuit card with at least one circuit. The circuit card comprises at least one power transistor. The power transistor also comprises a power transistor housing and at least three connecting electrodes, including a first electrode, a second electrode, and a third electrode, wherein at least three connecting electrodes extend from the power transistor housing on the same side. According to the present invention, the power transistor comprises an injection molded part comprising two regions. In the first region, the injection molded part extends the power transistor housing toward the connecting electrodes and surrounds the at least three electrodes together or as a whole, while in the second region, the injection molded part individually surrounds at least one of the three connecting electrodes, in particular the second electrode.

[0006] In a particularly preferred embodiment, the injection molding surrounds at least three connecting electrodes individually in each case in the second region.

[0007] The electric heating device is connected to a voltage source that provides voltage or current. This voltage source can be, for example, a battery installed in the vehicle. The electric heating device also includes at least one heating module that converts electrical energy into heat and outputs this heat to the fluid to be heated. The power supply to the heating element is controlled and / or regulated by a control unit that includes a circuit card with at least one circuit. This circuit card, also known as a printed circuit board or circuit board, can be designed, for example, as a printed circuit card or printed circuit board (PCB). At least one power transistor is used to control and / or regulate the power supply to the at least one resistance heating element and, therefore, the heat generated.

[0008] In all embodiments, the power transistor comprises at least one power transistor housing and at least three connection electrodes, including a first electrode, a second electrode, and a third electrode. The power transistor housing preferably comprises a dielectric or electrically insulating material, such as a plastic, particularly preferably a plastic based on polyamide (PA) or silicone. The power transistor housing is preferably cuboid in shape and may also comprise recesses, such as bevels, edges, or holes, as well as raised structures, such as projections, ridges, or ribs, which can be used, for example, for fastening to and / or alignment with other components.

[0009] At least three connecting electrodes are used to electrically connect or contact the power transistor to the circuit card and, in particular, to at least one circuit. Therefore, the connecting electrodes are made of an electrically conductive material, such as aluminum or copper. Because the power transistor, with which the connecting electrodes establish electrical contact, is arranged inside the power transistor housing, the connecting electrodes are guided inward through at least one opening in the power transistor housing. The number of openings preferably corresponds to the number of connecting electrodes, so that each connecting electrode is assigned an opening. The connecting electrodes are arranged in the power transistor according to the present invention so that they extend from the power transistor housing on the same side, with each connecting electrode preferably guided through its own opening. The openings are particularly preferably sealed so that dirt and, preferably, also liquids, cannot penetrate into the interior of the power transistor housing. Furthermore, embodiments are conceivable in which the three connecting electrodes are arranged along a straight line. In this case, the second electrode is preferably arranged between the first and third electrodes. The spacing between the first and second electrodes and the spacing between the second and third electrodes are particularly preferably the same.

[0010] The injection molded part has at least two regions. The first region extends and / or lengthens the power transistor housing in the direction in which the connecting electrodes extend from the power transistor housing. Preferably, the injection molded part continues the shape of the power transistor housing, for example, a cuboid shape, in the first region. Furthermore, the injection molded part surrounds all three connecting electrodes jointly or entirely in the first region, so that no free space remains between the connecting electrodes, but is completely filled with the injection molded material. The first region also serves to compensate for possible fluctuations or deviations in the dimensions of the power transistor or the power transistor housing, which may occur, for example, due to manufacturing tolerances or mechanical deformations of the connecting electrodes.

[0011] In the second region, the injection molded coating also follows the path of the connecting electrodes in the direction in which they extend from the housing. However, in the second region, unlike the first region of the injection molded coating, at least one connecting electrode is individually surrounded by the injection molded coating, thus forming its own continuation of the injection molded coating from the commonly surrounded first region. If more than one connecting electrode is surrounded by the injection molded coating, each connecting electrode forms its own continuation of the injection molded coating, which is separate from the injection molded coatings of the other connecting electrodes. Thus, in the second region, free space remains between the connecting electrodes surrounded by the injection molded coating, which is not filled with the injection molded coating. Particularly preferably, the cross-section of the connecting electrode along its extension is completely surrounded or enclosed by the injection molded coating in the first and second regions, so that the connecting electrode is not exposed at any point in the region of the injection molded coating. It should be noted that the injection molding ends in its course along the connecting electrode at a point behind the second region of the injection molding, so that the end of the connecting electrode is exposed and can be electrically connected to the circuit there.

[0012] The cross-section of the injection-molded encapsulation in the first region or the second region along the direction of extension of the connecting electrode is preferably mostly constant. The cross-section of the injection-molded encapsulation thus changes abruptly in the transition region from the first region to the second region, wherein, for example, a chamfer or radius may be incorporated into this transition region. However, embodiments are also conceivable in which the cross-section of the injection-molded encapsulation tapers or decreases from the first region toward the second region, thereby achieving a smooth transition between the two regions.

[0013] Preferably, the injection-molded encapsulation having at least two regions subsequently expands an already existing power transistor housing. This presupposes that a power transistor having a power transistor housing and at least three terminal electrodes is already present, which is subsequently provided with the injection-molded encapsulation in order to fulfill the task according to the present invention. The injection-molded encapsulation is thus applied in addition to the already existing power transistor housing.

[0014] The electric heating device preferably has at least one resistance heating element, for example a cold conductor, which has a positive temperature coefficient or PTC (positive temperature coefficient). The resistance heating element is heated by an electric current and the heat generated thereby is subsequently dissipated to the fluid, wherein the heat is preferably transferred via one or more indirectly heat-conducting components to a separate component that is thermally connected to the fluid and dissipates the heat to the fluid, for example a fin element around which the fluid flows and / or through which it flows.

[0015] Particularly preferably, the heating element is accommodated in a heating module housing, which can be designed as a flat tube and can also have heat-conducting elements on the outside, such as corrugated ribs. A fluid then flows around the heating module housing or through the heat-conducting elements, thereby improving the heat transfer from the heating element to the fluid.

[0016] In a preferred embodiment, at least one power transistor is embodied as a bipolar transistor with an insulated gate or as an insulated gate bipolar transistor (IGBT), wherein the first electrode is embodied as an emitter, the second electrode as a collector, and the third electrode as a base or gate.

[0017] In an alternative embodiment, at least one power transistor is designed as a metal oxide semiconductor field effect transistor (MOSFET), wherein the first electrode is designed as a source, the second electrode as a drain, and the third electrode as a gate.

[0018] The circuit card preferably has n+1 power transistors, where n corresponds to the number of heating modules in the electric heating device. This allows each heating module to be controlled or regulated by its associated power transistor. Additional power transistors are used, for example, to disconnect the entire electrical circuit of the electric heating device in the event of a fault.

[0019] In an advantageous embodiment, at least one of the three connecting electrodes has at least one section in which the cross section of the connecting electrode is increased compared to the rest of the connecting electrode, wherein this section is surrounded by the second region of the injection-molded coating.

[0020] For example, to increase strength locally, the cross section of the connecting electrode can be increased, wherein the cross-sectional expansion can be realized, for example, in a rectangular or circular shape when viewed from the side. Depending on the design, the cross section of the connecting electrode is increased so that the cross section of the second region of the injection-molded coating is also increased locally, so that the cross section of the connecting electrode is surrounded at each location.

[0021] Preferably, one of the at least three connecting electrodes has at least one bend. Particularly preferably, the bend forms a 90° angle, meaning that the connecting electrode is bent 90° at at least one location. In a particularly preferred variant, all three connecting electrodes are bent in the same direction. This allows the power transistor to be fastened to the circuit card and simultaneously connected to the circuit, since the bend allows the connecting electrode to be guided through an opening in the circuit card and, there, to be electrically contacted or connected to the circuit on the circuit card.

[0022] In a particularly preferred embodiment, the second region of the injection-molded encapsulation surrounds the bend of at least one of the three connecting electrodes. This encapsulation can occur completely or partially. In principle, embodiments are also conceivable in which only one or two bends of the at least three connecting electrodes are surrounded by the injection-molded encapsulation, i.e., not all of the at least three bends are surrounded by the injection-molded encapsulation.

[0023] The bend increases the stability of the connecting electrode on the one hand and also prevents the injection-molded coating from being damaged during the production process or during operation when the connecting electrode is mechanically loaded.

[0024] In another preferred embodiment, the power transistor has a heat sink or cooling surface. The heat sink or cooling surface is preferably located on the outer surface of the power transistor housing and is designed to be in thermally conductive contact with other heat-dissipating components, such as cooling ribs. Furthermore, the heat sink or cooling surface and one of the three connecting electrodes, preferably the second electrode, are connected to the same potential. If the power transistor is designed as an IGBT, the collector potential is applied both to the collector and to the heat sink. If the power transistor is designed as a MOSFET, the drain potential is applied both to the drain and to the heat sink.

[0025] In another preferred embodiment, the injection-molded encapsulation comprises a second material that is different from the first material of the power transistor housing and / or the second material of the injection-molded encapsulation has a CTI value greater than 400, preferably between 400 and 600, or alternatively greater than 600. The comparative value for creepage distance formation or the Comparative Tracking Index (CTI) allows for a comparison of the creepage strength or dielectric strength of insulating materials on their surfaces under specific environmental conditions, such as moisture or contamination. The CTI value specifies the voltage in volts (V) at which no creepage path forms, i.e., no conductive path forms on the surface of the insulating material. Generally, CTI values ​​are dimensionless, i.e., not expressed in V.

[0026] Particularly preferably, the second material of the encapsulation comprises a polyamide (PA)-based hot melt adhesive or a silicone-based material.

[0027] In another alternative embodiment, the second material of the injection-molded encapsulation and the first material of the power transistor housing have the same chemical composition. It should be clarified that two materials can be considered different within the meaning of this patent document if they are manufactured at different times. This makes it conceivable that the second material of the manufactured power transistor housing has the same chemical composition as the material of the injection-molded encapsulation, but that the injection-molded encapsulation was manufactured at a later time than the power transistor housing.

[0028] Furthermore, protection is claimed for a method for producing an electric heater, in particular for a vehicle, for warming a fluid, the method comprising at least the following steps:

[0029] - providing a power transistor having a power transistor body and at least three connecting electrodes, including a first electrode, a second electrode and a third electrode, wherein the at least three connecting electrodes protrude from the power transistor body at the same side,

[0030] - Place the power transistor into the mold,

[0031] - close the mold so that at least three connection electrodes are clamped in the mold,

[0032] - melting the second material of the encapsulation in the extruder,

[0033] - The molten second material of the encapsulation is conveyed to the mold.

[0034] Preferably, the molten material is conveyed by a hot runner nozzle. Alternatively, it can also be conveyed by a cold runner nozzle, wherein the gate must be cut off and removed in a further step.

[0035] The method for producing an electric heater is preferably designed such that the second material of the injection-molded encapsulation is different from the first material of the power transistor housing and / or the second material of the injection-molded encapsulation has a CTI value greater than 400, preferably between 400 and 600, or alternatively greater than 600. It is also preferred that the first material of the power transistor housing and the second material of the injection-molded encapsulation are identical in terms of their chemical composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further details and advantages of the present invention will be found in the following description of exemplary embodiments in conjunction with the accompanying drawings.

[0037] Figure 1 A schematic diagram showing an embodiment of an electric heating device;

[0038] Figure 2 A schematic diagram showing a cross section of a heating module;

[0039] FIG. 3 shows a preferred embodiment of a power transistor before the application of the encapsulation in different views, wherein: Figure 3a shows a front view, Figure 3b A side view is shown and Figure 3d Shows a top view and Figure 3c Two sections AA, BB are shown and Figure 3e Section CC is shown;

[0040] FIG. 4 shows a preferred embodiment of a power transistor in different views after application of the encapsulation, wherein: Figure 4a shows a front view, Figure 4b A side view is shown and Figure 4d Shows a top view and Figure 4c Three sections AA, BB, CC are shown and Figure 4e Section DD is shown;

[0041] FIG. 5 shows another preferred embodiment of a power transistor in different views after application of the encapsulation, wherein: Figure 5a shows a front view, Figure 5b A side view is shown and Figure 5d Shows a top view and Figure 5c Three sections AA, BB, CC are shown and Figure 5e Section DD is shown;

[0042] FIG6 shows an isometric view of the top side of an exemplary embodiment of a power transistor, wherein Figure 6a The power transistor is shown before the application of the encapsulation and Figure 6b shows a power transistor after application of the injection-molded encapsulation;

[0043] FIG7 shows an isometric view of the underside of an exemplary embodiment of a power transistor, wherein Figure 7a The power transistor is shown before the application of the encapsulation and Figure 7b shows a power transistor after application of the injection-molded encapsulation;

[0044] Figure 8 An exemplary embodiment of a power transistor with an encapsulation is shown in plan view and side view with selected dimensions. DETAILED DESCRIPTION

[0045] Figure 11 shows a schematic diagram of an embodiment of an electric heating device 100. The electric heating device 100 can be arranged, for example, in an air-conditioning system (not shown) in a vehicle and / or be connected to this air-conditioning system.

[0046] The electric heating device 100 includes a control unit 101 with a control housing 102 and a circuit card 103 mounted therein. The circuit card 103 is shown as rectangular, although other more complex shapes are also possible. The circuit card 103 includes an electrical circuit (not shown) and a power transistor 104, which is electrically connected to the circuit via a terminal electrode 105.

[0047] The electric heating device also includes at least one heating module 107, which is electrically connected to the control unit 101 and the circuit card 103. The heating module 107 also includes a heating module housing 109 and a heat transfer element 108, through which the fluid to be heated flows and / or around which the fluid to be heated flows, thereby exchanging heat with the fluid. In the illustrated embodiment, the heating module 107, along with a portion of the heating module housing 109, is guided through an opening in the control housing 102, thereby enabling a simple electrical connection between the heating module 107 and the circuit card 103.

[0048] Also shown is a voltage source 106, which supplies voltage or current to the heating device 100. This can be, for example, a battery installed in the vehicle. The voltage source is electrically connected to the control unit 101 and the circuit card 103, for example, via a plug at the control housing 102 and via cables or busbars inside the control housing 102 to corresponding electrical connections on the circuit card.

[0049] The power transistor 104 , the heating module 107 , and the voltage source 106 are interconnected via a circuit so that the circuit through the power transistor 104 can supply current or voltage from the voltage source 106 to the heating module 107 , so that the heating module 107 converts the current into heat and outputs it to the fluid to be heated.

[0050] The number of power transistors 104 is based on the number of heating modules 107. In the illustrated embodiment, the electric heater 100 has two heating modules 107. Therefore, the circuit card 103 has three power transistors 104, two of which are each assigned to a heating module 107 and, by switching, control or regulate the voltage or current supplied to the corresponding heating module 107. The third power transistor 104 serves as an additional safety feature, for example, to disconnect the electrical circuit of the electric heater 100 in the event of a fault.

[0051] Figure 2A schematic cross-sectional view of a heating module 107 of an electric heating device 100 is shown. The heating module includes at least one heating element 112, which is arranged between and electrically connected to two contact electrodes 111. Both contact electrodes 111 have an insulator 110 on the side facing away from the heating element 112, which electrically insulates the contact electrodes 111 from the surrounding heating module housing 109. During operation, the contact electrodes 111 are each connected to the potential of a voltage source 106, so that current flows through the heating element 112, thereby heating it. Heat is transferred to the heating module housing 109 via the contact electrodes 111 and the insulator 110. Heat-conducting elements 108, in this case in the form of ribs, are mounted on the outside of the heating module housing 109. These heat-conducting elements are in thermal contact with the fluid to be heated, and the fluid to be heated flows around the heat-conducting elements 108 and the heating module housing 109.

[0052] FIG. 3 shows a preferred embodiment of a power transistor 200 in the initial state, ie before the application of the encapsulation, from different views, wherein: Figure 3a shows a front view, Figure 3b A side view is shown and Figure 3d A top view is shown. Figure 3c Sections AA and BB are shown in FIG, and Figure 3e The section CC is shown in The power transistor 200 comprises a power transistor body 201 and three connecting electrodes 202 , which include a first electrode 203 , a second electrode 204 and a third electrode 205 , wherein the connecting electrodes 202 project from a common side of the power transistor body 201 .

[0053] The three connecting electrodes 202 are as shown in Figure 3c As can be seen in the section AA of FIG. , the electrodes 202 have a uniform, regular cross section, wherein an embodiment is also conceivable in which one or more connecting electrodes 202 have different cross sections. All three connecting electrodes 202 also each have a section 210 with an increased cross section. Figure 3cThis can be seen in section BB. In particular, the difference between section AA, which shows a regular cross section of connecting electrode 202, and section BB, which shows a section 210 of connecting electrode 202 with an increased cross section, can be seen. It can be seen that in the illustrated embodiment, the cross-sectional change is limited to widening of connecting electrode 202 in the Y direction. However, embodiments are also conceivable in which section 210 with an increased cross section increases only in the X direction, or in both the X and Y directions. Furthermore, it can be seen that the cross-sectional changes of the three connecting electrodes 202 are not designed to be uniform, but rather that first electrode 203 and third electrode 205 have a smaller cross-sectional increase than second electrode 204.

[0054] Furthermore, the three connecting electrodes 202 each have a 90° bend 211 with a radius. Figure 3b In the side view and Figure 3e In the embodiment shown, the bend is designed uniformly for all three connecting electrodes 202. The bend 211 is arranged along the course of the connecting electrode 202, starting from the power transistor housing 201, after the section 210 with the increased cross section.

[0055] Furthermore, the power transistor 200 has a heat sink or cooling surface 206 , which is arranged on a main side of the power transistor housing 201 and is designed to be connected in a heat-conducting manner to a heat-dissipating element, such as a cooler or a heat pipe.

[0056] The three connecting electrodes 202 are designed to be connected to three different potentials via an electrical circuit. As a result, in the installed state, the first electrode 203 is connected to a first potential, the second electrode 204 is connected to a second potential, and the third electrode 205 is connected to a third potential. In the illustrated embodiment, a potential corresponding to the potential of the second electrode 204 is also applied to the heat sink 206.

[0057] In order to fix the power transistor 200 in its position, for example on a circuit card, a cutout 212 and a hole 213 are provided on the power transistor housing 201. In the embodiment shown, the cutout 212 is, for example, Figure 3b As can be seen in FIG, the holes 213 are arranged as half blind holes on both sides of the power transistor housing 201. In particular, the cutouts serve to fix the power transistor 200 in the XY plane, for example by engaging in a positive-locking manner with matching protrusions or protruding pins on the circuit card. In the present embodiment, the hole 213 is designed as a central through-hole through the power transistor housing 201 along the Z axis, as shown in FIG. Figure 3b Neutralization Figure 3eAs can be seen in the section CC of FIG. , the holes 213 serve to fasten the power transistor housing 201 to the circuit card in a form-fitting and / or friction-fitting manner, for example by screws.

[0058] FIG. 4 shows a preferred embodiment of the power transistor 200 of FIG. 3 in the final state, ie after the application of the injection-molded encapsulation 207 , from different views, wherein: Figure 4a shows a front view, Figure 4b A side view is shown and Figure 4c The cross sections AA, BB and CC along the Y axis are shown in FIG. Figure 4c The cross section DD along the X-axis is shown in FIG. Figure 4e Shown in.

[0059] As in Figure 4a 、 4b As can be seen in FIG4d, the connecting electrode 202 is partially surrounded by the injection molding 207. This injection molding is as shown in FIG4d. Figure 4e As can be seen in the cross section CC of FIG, it has a first region 208 and a second region 209. The first region 208 of the injection molded portion is seamlessly connected to the power transistor housing 201 along the direction of the X axis and therefore has the same dimensions in both the Y direction and the Z direction, as shown in FIG. Figure 4b and Figure 4d in and Figure 4e It should be noted that slight deviations may always occur when continuing the contour of the power transistor housing 201 , for example due to manufacturing tolerances.

[0060] In the first region 208 of the injection-molded coating, the three connecting electrodes 202 are completely surrounded by the injection-molded coating 207 , as shown in FIG. Figure 4c As can be seen in the cross section CC of FIG. , the space between the three connecting electrodes in the cross section CC shown is completely filled with the material of the injection molding 207. Since the contour of the power transistor housing 201 is continued, the cross section of the injection molding 207 in the first region 208 is constant.

[0061] The second region 209 of the injection-molded coating seamlessly connects to the further course along the X axis, in which second region the second electrodes 202 , 204 have a separate injection-molded coating 207 , as in Figure 4c As can be seen in the cross sections AA and BB.

[0062] and Figure 3c Similar, in Figure 4c, section BB shows the region 210 of the connecting electrode with an increased cross section, and section AA shows the region of the connecting electrode 202 with a regular cross section. It can be seen that the cross section of the injection molding 207 surrounding the second electrodes 202, 204 is larger than the region 210 of the connecting electrode with an increased cross section, and therefore completely surrounds the second electrodes 202, 204 both in the section with a regular cross section (section AA) and in the section with an increased cross section 210 (section BB).

[0063] also, Figure 4c It is also shown that the cross-section of the injection-molded part 207 around the second electrodes 202, 204 remains constant in the second region of the injection-molded part, more precisely, regardless of the change in the cross-section of the connecting electrode from the increased cross-section in the region 210 (visible in the section BB) to the regular cross-section (visible in the section AA).

[0064] It is explicitly mentioned that in the transition region from first region 208 to second region 209 and at the end of second region 209, each viewed along the X-axis, manufacturing-related deviations from a constant cross-sectional profile may occur, for example due to the necessity of providing radii or roundings in the transition region during manufacturing methods such as injection molding. Within the meaning of the present invention, these manufacturing-related geometries, both in first region 208 and in second region 209, are not considered to be deviations from the constant profile of the cross section of injection-molded coating 207.

[0065] As in Figure 4e As can be seen in the cross-section DD of FIG, the bend 211 of the second connecting electrodes 202 and 204 is also surrounded by the injection molded part 207. The bend 211 changes the direction of the connecting electrode 202. In the illustrated embodiment, the 90° angle of the bend 211 changes the direction of the connecting electrode 202 from its previous direction along the X-axis to one along the Z-axis. However, since the cross-section of the injection molded part 207 extends uniformly along the X-axis, the second electrodes 202 and 204 exit the cross-section of the injection molded part 207 after the bend and leave this cross-section. As a result, the three connecting electrodes 202 are exposed in the area behind the bend and can be electrically connected to corresponding contacts on the circuit card 103.

[0066] FIG. 5 shows another preferred embodiment of the power transistor 200 of FIG. 3 in the final state, ie after the application of the encapsulation 207 , from different views, wherein: Figure 5a shows a front view, Figure 5b A side view is shown and Figure 5cThe cross sections AA, BB and CC along the Y axis are shown in FIG. Figure 5c The cross section DD along the X-axis is shown in FIG. Figure 5e Shown in.

[0067] 4 is that in the second region 209 of the injection-molded portion, all three connecting electrodes 202 are individually surrounded by the injection-molded portion 207, as in Figure 5c As can be seen in the sections AA and BB of FIG. Thus, in the cross section shown, a free space is created between the connecting electrodes 202 , which free space does not contain the material of the injection-molded encapsulation 207 .

[0068] It can also be seen that in the illustrated embodiment, the cross-section of the injection-molded encapsulation 207 around the second electrode 204 is larger than the cross-section of the injection-molded encapsulation 207 around the first electrode 203 and the third electrode 205. This is due to the fact that the electrode cross-section of the second electrode 204 is significantly larger in the region 210 of increased cross-section than the electrode cross-sections of the first electrode 203 and the third electrode 205. The cross-section of the injection-molded encapsulation 207 is therefore adapted to the contour or cross-section of the respective connecting electrode 202 in the region having the greatest extent.

[0069] FIG6 shows an isometric view of the top side of an exemplary embodiment of a power transistor 200 , wherein Figure 6a The power transistor 200 is shown before the injection molding encapsulation 207 is applied and Figure 6b The power transistor 200 is shown after the injection molding encapsulation 207 has been applied. The power transistor housing 201 with the heat sink 206, the cutout 212, the hole 213, and the three connecting electrodes 202, 203, 204, 205 can be seen. As already mentioned above, different potentials are applied to the connecting electrode 202. In addition, a potential is also applied to the heat sink 206, wherein this potential corresponds to the potential of the second electrode 204. Figure 6a The creepage distance 214 between the first electrode 203 and the heat sink 206 or between the third electrode 205 and the heat sink 206 is plotted in FIG. As already explained, the creepage distance 214 is the shortest distance along the surface of a non-conductive component (insulator) between two conductive components. The two creepage distances 214 are also Figure 6b , wherein the creepage distance 214 is extended by the injection molding part 207, because the injection molding part 207 comprises a second non-conductive material. The creepage distance between the second electrode 204 and the heat sink 206 is not important, because the same potential is applied at both points. Figure 6bA first region 208 and a second region 209 of the injection-molded encapsulation can be seen, wherein the cross section of the injection-molded encapsulation 207 in the first region 208 follows the cross section of the power transistor housing 201 and the cross section of the injection-molded encapsulation 207 in the second region 209 provides an air-filled intermediate space between the connecting electrodes 202 .

[0070] FIG7 shows an isometric view of the underside of an exemplary embodiment of a power transistor 200 , wherein: Figure 7a The power transistor 200 is shown before the injection molding encapsulation 207 is applied and Figure 7b The power transistor 200 is shown after the application of the injection molding encapsulation 207. The power transistor housing 201 with the cutout 212 and the hole 213 as well as the three connecting electrodes 202 can be seen, wherein different potentials are applied to each of the three connecting electrodes. Figure 7a The creepage distances 214 between the first electrode 203 and the second electrode 204 or between the second electrode 204 and the third electrode 205 are drawn in FIG. Figure 7b In FIG, the creepage distance 214 is extended by the injection molding encapsulation 207, since the injection molding encapsulation 207 comprises a second non-conductive material. Figure 7b It can also be seen that the connecting electrode 202 emerges from the region of the injection-molded encapsulation 207 along the Z axis.

[0071] Figure 8The most important dimensions of an exemplary embodiment of a power transistor 200 for an electric heater are shown. The embodiment shown is designed for an electric heater that can be supplied with an 800 V battery voltage. The power transistor 200 with the injection-molded encapsulation 207 according to the present invention can be seen in top and side views. Dimension D1 indicates the width of the power transistor housing 201 in the Y direction and, in this example, is 15.45 mm. The width of the injection-molded encapsulation 207 around the centrally arranged connecting electrode 202 is 4.80 mm (denoted by D2) and 2.90 mm (denoted by D3) around each of the two lateral connecting electrodes 202. Dimension D4 indicates the spacing between the injection-molded encapsulation 207 around the connecting electrodes 202 in the second region of the injection-molded encapsulation 207 and is 1.60 mm on both sides. The height of the power transistor housing 201 in the Z direction, and therefore also the height of the injection-molded encapsulation 207 in the first region 208, is denoted by dimension D5 and is 5.00 mm. Dimension D6 describes the height of the injection-molded encapsulation 207 in the second region 209 and is 2.80 mm in the example shown. All dimensions are always taken into account for the tolerances typically encountered during plastic injection molding, which can result in dimensional deviations. The aforementioned dimensions D1 to D6 allow for a creepage distance of greater than 8 mm between the connecting electrode 202 and the heat sink 206 and a creepage distance of greater than 6 mm between the first electrode 203 and the second electrode 204 or between the third electrode 205 and the second electrode 204.

[0072] Reference Signs List

[0073] 100 electric heating device

[0074] 101 control unit

[0075] 102 control housing

[0076] 103 circuit card

[0077] 104 power transistors

[0078] 105 connecting electrode

[0079] 106 voltage source

[0080] 107 heating module

[0081] 108 heat transfer elements

[0082] 109 heating module housing

[0083] 110 insulator

[0084] 111 contact electrode

[0085] 112 heating element

[0086] 200 power transistors

[0087] 201 power transistor housing

[0088] 202 connecting electrode

[0089] 203 first electrode

[0090] 204 second electrode

[0091] 205 third electrode

[0092] 206 radiator or cooling surface

[0093] 207 Injection Molding Department

[0094] 208 first region of the injection-molded portion

[0095] 209 second region of the injection molded portion

[0096] 210 connecting the section of the electrode with the increased cross section

[0097] 211 bend

[0098] 212 blank space

[0099] 213 holes

[0100] 214 creepage distance

[0101] D1 Width of the encapsulation in the first region

[0102] D2 Width of the injection-molded encapsulation in the second region around the central connecting electrode

[0103] D3 Width of the injection-molded coating around the outer connecting electrode in the second region

[0104] D4 Distance of the injection-molded part around the connecting electrode in the second region

[0105] D5 Height of the encapsulation in the first region

[0106] D6 Height of the encapsulation in the second region

Claims

1. An electric heating device (100) for heating a fluid, in particular for a vehicle, comprising a control unit (101) comprising at least one circuit card (103) with at least one circuit, wherein: The circuit card (103) has at least one power transistor (104, 200), the power transistor having a power transistor housing (201) and at least three connecting electrodes (105, 202), wherein a first electrode (203), a second electrode (204) and a third electrode (205) are provided, wherein the at least three connecting electrodes (105, 202) extend from the power transistor housing (201) at the same side, and is characterized in that the power transistor (104, 200) has an injection-molded encapsulation portion (207), wherein the injection-molded encapsulation portion (207) includes - a first region (208), in which the injection molding (207) extends the power transistor housing (201) in the direction of the connecting electrodes (105, 202) and jointly surrounds at least three electrodes (203, 204, 205), and A second region (209) in which the injection molding (207) individually surrounds at least one of the three connecting electrodes (105, 202), in particular the second electrode (204).

2. The electric heating device (100) according to claim 1, characterized in that: In a second region (209) of the injection-molded coating, the injection-molded coating (207) surrounds the at least three connecting electrodes (105, 202) individually.

3. The electric heating device (100) according to any one of the preceding claims, characterized in that The at least one power transistor (104, 200) is implemented as a bipolar transistor (IGBT) with an insulated gate, wherein the first electrode (203) is implemented as an emitter, the second electrode (204) is implemented as a collector, and the third electrode (205) is implemented as a base.

4. The electric heating device (100) according to any one of the preceding claims, characterized in that At least one of the three connecting electrodes (105, 202) has at least one section (210) in which the cross section is enlarged compared to the remainder of the electrode, and the second region (209) of the injection-molded part surrounds the section of the at least one of the three connecting electrodes (105, 202).

5. The electric heating device (100) according to any one of the preceding claims, characterized in that At least one of the three connecting electrodes (105, 202) has at least one bend (211) preferably with an angle of 90°.

6. The electric heating device (100) according to claim 5, characterized in that: The second region (209) of the injection-molded coating surrounds the bend (211) of at least one of the three connecting electrodes (105, 202).

7. The electric heating device (100) according to any one of the preceding claims, characterized in that The power transistor (104, 200) has a heat sink or cooling surface (206), and both the heat sink or cooling surface (206) and one of the three connecting electrodes (105, 202), preferably the second electrode (204), are connected to the same potential.

8. The electric heating device (100) according to any one of the preceding claims, characterized in that The injection molding (207) comprises a second material which is different from the first material of the power transistor housing (201) and / or the second material of the injection molding (207) has a CTI value greater than 400, preferably between 400 and 600 or alternatively greater than 600.

9. A method for producing an electric heating device (100) for heating a fluid, in particular for a vehicle, comprising at least the following steps: A power transistor (104, 200) is provided, comprising a power transistor housing (201) and at least three connection electrodes (105, 202), of which a first electrode (203), a second electrode (204) and a third electrode (205) are provided, wherein: The at least three connecting electrodes (105, 202) protrude from the power transistor housing (201) at the same side, - placing the power transistor (104, 200) into a mold, - closing the mold so that the at least three connecting electrodes (105, 202) are clamped in the mold, - melting the second material of the encapsulation (207) in an extruder, - The molten second material of the encapsulation ( 207 ) is conveyed to the mold.

10. The method for manufacturing an electric heating device (100) according to claim 9, characterized in that: The second material of the injection-molded encapsulation (207) is different from the first material of the power transistor housing (201) and / or the second material of the injection-molded encapsulation (207) has a CTI value greater than 400, preferably between 400 and 600, or alternatively greater than 600.

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