Electric heating device

Abstract

The invention relates to an electric heating device (2) comprising: an electric heating device (22); a control device (36) designed to control the electric heating device (22); having at least one power switch (246) generating loss power; and a housing base (4) designed to receive the control device (36), which housing base is connected to the housing cover (42) to form a housing (44) that is sealed against the environment and which at least partially forms a heating chamber (6.1) or receives a heating chamber (6.2), to which a power switch (246) is coupled in a thermally conductive manner. In the electric heating device (2) according to the invention, a pressing element (230), which preforces the power switch (246) in the direction of the heating chamber (6.2), is arranged in the housing on the opposite side of the heating chamber (6.2) from the control device (36), and the pressing element is connected to the housing base (4).

Description

Technical Field

[0001] The invention relates to an electric heating device, comprising an electric heating device and a control device designed to control the electric heating device, the control device having at least one power switch generating power loss. In addition, the electric heating device has a housing having a housing base and a housing cover connected to the housing base, and the control device is accommodated in the housing. The housing at least partially forms a heating chamber or accommodates a heating chamber, and the power switch is connected to the heating chamber in a heat-conducting manner. Background Art

[0002] An electric heating device is known from DE 20 2019 005 223 U1, in which a cooling body is connected to a heating chamber which is formed at least partially by a housing.

[0003] In this prior art, the pressure piece is supported on the housing cover and presses the circuit breaker in a heat-conducting manner against a partition wall, from which heating ribs of the electric heating device protrude, which heating ribs extend into the heating chamber. Summary of the invention

[0004] The invention is based on the problem of providing an electric heating device of the type mentioned at the outset which can be assembled more easily.

[0005] In view of this, the present invention proposes to connect a pressing piece arranged in the housing to the housing base, the pressing piece being arranged on the side of the heating chamber opposite to the control device. Such a pressing piece preloads the power switch toward the heating chamber. Different from the above-mentioned prior art, the pressing piece is not supported on the housing cover, but is connected to the housing base.

[0006] The design according to the invention provides the possibility of assembling all components (in particular the electric heating device, the heating chamber if applicable, and the control device in any case) in the housing base and positioning them relative to one another when the housing cover is removed. The assembly also includes the pre-stressing assembly of the power switch connected to the heating chamber in a heat-conducting manner when the housing cover is still open. In contrast to the previously mentioned prior art, the proper arrangement of the pressure piece and its effectiveness for pre-stressing at least one power switch can be checked before the housing is closed.

[0007] Since the control device is accommodated in the housing in the solution according to the invention, the best possible EMC protection can be produced by suitable choice of the material forming the housing, so that other electrical and electronic components in the vehicle are not disturbed by the operation of the electric heating device. The electric heating device of the invention is particularly suitable for operation with high voltage currents, such as those used for the drive of electric vehicles. According to the invention, currents greater than 400 volts, possibly greater than 700 volts, are considered to be high voltage currents.

[0008] According to the present invention, the control device and the electric heating device are accommodated in the housing.

[0009] The housing base preferably has a generally flat housing bottom which delimits the housing, the housing bottom generally extending substantially parallel to the housing cover. These parts of the housing are generally made of a metallic material; in any case, this material has good electromagnetic shielding properties. A housing made of a synthetic material is also feasible, wherein a housing shielding device is inserted into the housing or surrounds or shields the housing, for example formed by a wire mesh. The accommodation space formed by the housing for accommodating all the components of the electric heating device is preferably limited only by the two parts, the housing base and the housing cover.

[0010] In contrast to the previously mentioned prior art, in which the medium to be heated is accommodated in a heating chamber which is surrounded and delimited on the one hand by a partition wall of the control housing and on the other hand by a fluid housing which may be made of synthetic material, it is preferred in the present invention that the fluid to be heated is at least also guided in a fluid housing which is accommodated in the housing and is designed to be suitable for guiding the medium to be heated through it. The fluid housing is usually closed and has only predetermined inlets and outlets through which the medium is introduced into the fluid housing or discharged.

[0011] The fluid housing is connected to the electric heating device in a heat-conducting manner. This is to be understood in particular as meaning that the fluid housing rests against the electric heating device in a heat-conducting manner. In order to achieve the most efficient heat output possible, the fluid housing is usually made of a material with good heat conductivity, usually a metal, such as aluminum or an aluminum alloy. With regard to the electrical insulation of the fluid housing from the electric heating device, an insulating layer can be provided between the fluid housing and the electric heating device, the insulating layer being made, for example, of a synthetic material film, a ceramic plate or a coated plate or a combination thereof, for example formed by a covering synthetic material film or a ceramic plate held in between.

[0012] According to a preferred development of the invention, the electric heating device is thermally coupled to the housing bottom of the housing base, which delimits the first heating chamber. Here, the insulating layer as described above can also be arranged between the electric heating device and the housing bottom. The electric heating device is then preferably arranged between the fluid housing and the housing bottom, usually as a flat component with an extension parallel to the housing bottom and parallel to the fluid housing, which fluid housing is preferably also designed to be flat.

[0013] In order to improve the heat output, the electric heating device bears against the housing bottom and the fluid housing under pretension. For this purpose, preferably an elastic pretensioning device is provided, in particular an elastic pretensioning device formed of a compressible material. This material can be located on the side of the fluid housing opposite to the heating direction and can act there in such a way that the fluid housing bears against the electric heating device under pretension and the electric heating device bears against the housing bottom under pretension. In this variant, the elastic pretensioning device is located between the electric heating device and the fluid housing. Alternatively or additionally, the pretensioning device can also be arranged between the electric heating device and the housing bottom.

[0014] With regard to good heat output, synthetic material films, in particular silicone films, arranged between the fluid housing and the electric heating device or between the fluid housing and the housing bottom, in which the fluid housing is screwed to the housing, in particular the housing bottom of the housing base, have also proven to be effective as elastic preload means. The corresponding films usually have a base surface that covers at least the heat-outputting base surface of the electric heating device.

[0015] It is obvious from the above description that the fluid housing forming the heating chamber can be connected to the housing base together with the electric heating device. Of course, in this configuration, the control device is arranged on a side of the fluid housing forming the heating chamber away from the electric heating device. In this configuration, the circuit board of the control device can be connected separately, especially threadedly connected to the housing base. In this configuration, the pressing piece only acts on the power switch and abuts against the fluid housing under preload. In order to properly position the pressing piece, so that the preload force caused by the pressing piece acts on the corresponding power switch in an accurately positioned manner, it is proposed according to a preferred improvement of the present invention that a positioning element extends from the housing bottom formed by the housing base, and the positioning element penetrates the positioning hole electrically connected to the power switch on the circuit board and is accommodated in the positioning accommodating portion of the pressing piece. These positioning elements are locally referenced to the pressing piece and the circuit board. Of course, the positioning element penetrates the positioning hole only with a small clearance, so that the desired relative alignment between the circuit board and the pressing piece is achieved due to the positioning element. In this design, the circuit board preferably extends parallel to the housing bottom. The positioning element usually penetrates the plane containing the fluid housing.

[0016] At least one of the positioning elements and generally all positioning elements are preferably formed by a fixing pin, particularly preferably by a fixing screw. The fixing pin can be connected to the housing bottom and / or the pressure piece. This expression means that the fixing pin is connected to the housing bottom and / or the pressure piece during assembly. If, for example, a screw is used, an internal thread is generally provided on the housing base, into which the screw for fixing the pressure piece is screwed.

[0017] According to another preferred design of the present invention, at least one power switch is arranged on the side of the circuit board facing the heating chamber. The circuit board has an opening, and the preload applied by the press piece is transmitted to the power switch through the opening. This is preferably done by an elastic compression element, which runs through the opening and is supported on the press piece on one side and on the power switch on the other side. In order to facilitate the design of assembly, the compression element is usually a part of the press piece. The press piece can have a press piece carrier, which is usually made of a hard synthetic material such as PP (polypropylene), PE (polyethylene) or PA (polyamide), and a compression element made of a soft elastic synthetic material such as TPE (thermoplastic elastomer) is installed thereon. The connection between the press piece carrier and the compression element can be achieved, for example, by composite injection molding of two different synthetic materials. Of course, the compression element can also be connected to the press piece carrier in other ways.

[0018] The electric heating device according to the invention usually has a plurality of power switches. According to a preferred development of the invention, the power switches are arranged adjacent to one another, if necessary in a row, and are usually arranged adjacent to the edge of the heating chamber. The power switch is then located above the heating chamber, but is arranged adjacent to the edge of the heating chamber. The pressure piece has a wide side on one side of the power switch and a narrow side opposite it. Both the wide side and the narrow side extend out of the heating chamber and are connected to the base of the housing. The wide side is assigned to the power switch. There are more fixing pins on the wide side than on the narrow side. Despite the lightweight design, sufficient preload force acting on each power switch is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 1 A perspective exploded view showing an embodiment of the present invention;

[0021] Figure 2 Show according to Figure 1 A perspective exploded view of a housing base and a heating chamber cover of an embodiment of the present invention;

[0022] Figure 3 Show according to Figure 1 A perspective exploded view of a fluid housing of an embodiment of the invention;

[0023] Figure 4 Show according to Figure 1 A perspective top view of a housing base partially equipped with components of an embodiment of the present invention;

[0024] Figure 5 Shown along Figure 4 A cross-sectional view of the embodiment shown along line VV;

[0025] Figure 6 A perspective exploded view showing a slightly modified embodiment;

[0026] Figure 7 a perspective top view showing the housing base equipped but not yet closed; and

[0027] Figure 8 The figure shows a perspective top view of the underside of an exemplary embodiment of a pressure piece. DETAILED DESCRIPTION

[0028] Figure 1 An electric heating device 2 is shown having a housing base 4, which is located at Figure 1 The lower side of the heating chamber is connected to the heating chamber cover 8 to form the first heating chamber 6.1, see Figure 2 Reference numeral 10 denotes a fluid housing, which is accommodated in an accommodation space 12 formed by the housing base 4. In this accommodation space 12, which is delimited on the lower side by a base 14 and on the edge by a surrounding wall 16 extending from the base 14, there is a first insulating layer 18 that can be abutted against the base 14, a first contact connection layer 20 and a heating device 22 with a plurality of heating elements 23, here in the form of PTC elements 24, and a positioning frame 26 with a receptacle 28 for receiving the PTC elements 24 between the base 14 and the fluid housing 10.

[0029] On the side of the heating device 22 opposite to the first contact connection layer 20, a second contact connection layer 30 is provided, and on the side opposite to the heating device 22, a second insulating layer 32 is provided. Therefore, the PTC element is conductively pressed against the contact connection layers 20, 30 and is energized via the contact connection layers. The PTC element 24 is a ceramic cuboid component, which is provided with a metallization portion on the opposite main side surface for current introduction. The main side surface is the surface of the cuboid with the largest planar extension. The main side surfaces are connected to each other by edge surfaces, which determine the height of the PTC element and have no metallization portion. The main side surface is usually 5 times larger than one of the edge surfaces, preferably 5 times larger than the sum of all edge surfaces.

[0030] The second insulating layer 32 is formed from a silicone film as a prestressing device 33 which can withstand a certain compression by elastic deformation and thus the electric heating device 22 between the housing base 10 and the housing bottom 14 rests against the housing base 10 and the housing bottom 14 under prestressing.

[0031] The layering of the first insulation layer 18 , the first contact-connection layer 20 , the heating device 21 , the second contact-connection layer 30 and the second insulation layer 32 is also referred to below as a layered structure 34 .

[0032] In the exemplary embodiment shown, on the side of the fluid housing 10 facing away from the layered structure 34, a transistor insulator 40 is located between a circuit board 38 forming the control device 36 and the fluid housing 10. Reference numeral 42 denotes a housing cover, which is provided for forming a Figure 5 The housing 4 is connected to the housing base 4 by the housing marked with reference numeral 44. The housing base 4 and the housing cover 42, and possibly other housing parts, are designed to be shielded, i.e. made of metal and / or a separate shield is provided inside, outside or inside the wall of the corresponding housing part. Aluminum or, preferably, stainless steel is preferably used as the metal material for corrosion resistance.

[0033] On the lower side of the housing base 4 opposite the housing cover 42, Figure 1 4 shows a power plug 46 and a control plug 48. The two plugs 46, 48 are connected to the housing base 4 in a sealed manner and have various male electrical plug contacts, which penetrate the respective housings of the plugs 46, 48 in a sealed manner and make plug contacts in the circuit board 38 and are electrically connected to the conductor tracks of the circuit board 38 via the plug contacts. Figure 4 Detailed description: For the plug contact, the circuit board 38 has a female contact tongue socket, which is described in EP 2 236 330 A1.

[0034] An inlet port 50 and an outlet port 52 are also provided on the lower side for connecting a pipe or a hose for conveying the fluid to be heated. Figure 1 , which is formed in this case by two sealing rings 54, as will be explained in more detail below. Reference numeral 56 denotes a screw for fixing the fluid housing 10 relative to the housing base 4 with the layered structure 34 in between. By means of the threaded connection, the layers of the layered structure 34 bear against the fluid housing 10 and the bottom 14 of the housing base 4 under preload.

[0035] Figure 2 An exploded view of the housing base 4 and the heating chamber cover 8 shown spaced therefrom is shown, and the interior of the first heating chamber 6.1 is shown. As shown, the ports 50, 52 are formed by separate components which align with two holes in the heating chamber cover 8 formed by a flat plate, one of which forms the inlet 58 and the other forms the outlet 60. The ports 50, 52 may be welded or glued to the heating chamber cover 8.

[0036] Reference numeral 62 denotes a distributor arranged in a plane HE containing the first heating chamber 6.1. The distributor 62 has an inlet distributor segment 64 and an outlet distributor segment 66, which are arranged independently of each other and covered by the heating chamber cover 8. The corresponding distributor segments 64, 66 are arranged symmetrically about the longitudinal axis L of the housing base 4 and are assigned an inlet branch 68 or an outlet branch 70 of the first heating chamber 6.1. In a plan view, the distributor segments 64, 66 have a base surface that is approximately triangular. Each distributor segment 64, 66 is merged into a corresponding branch 68, 70 via an overflow edge 72. The overflow edge 72 is located in the height direction between the first heating chamber bottom 74 of the first heating chamber 6.1 and the opposite covering surface of the first heating chamber 6.1 formed by the heating chamber cover 8.

[0037] Flow guide ribs 76 project from the first heating chamber bottom 74 in order to guide the flow, against which the heating chamber cover 8 rests in a fluid-tight manner.

[0038] The inlet 58 and the outlet 60 are each arranged such that they partially cover the first heating chamber 6 . 1 and partially cover the respective distributor segment 64 , 66 . Here, the overflow edge 72 runs approximately through the center of the hole forming the inlet 58 or the outlet 60 .

[0039] Details of the second heating chamber 6.2 are given in Figure 3 The fluid housing 10 is formed by a fluid housing base 78 and a fluid housing cover 80 welded thereto. The second heating chamber 6.2 also has a flow guide rib 76. A plurality of fixing holes 82 are arranged on the circumference of the fluid housing 10, and screws 56 pass through the fixing holes 82 so as to connect the fluid housing 10 to the housing bottom 14 with the electric heating device 22 placed in the middle. Figure 4 In the embodiment, the thread formed on the housing bottom 14 is denoted by reference numeral 83 .

[0040] exist Figure 4 In the embodiment of the present invention, reference numeral 84 denotes a first inlet channel segment and reference numeral 86 denotes a first outlet channel segment. These channel segments 84, 86 are formed on the housing base 4 and penetrate the housing base 4. Figure 3 Second inlet and outlet channel segments 88 , 90 are shown formed as one piece on the fluid housing base 78 .

[0041] In particular Figure 5 As shown, the second channel segments 88 , 90 are designed as tips 92 , which are each engaged in a socket end 94 formed by the first channel segments 84 , 86 , with the sealing structure 53 arranged between them and abutting against abutment shoulders 96 in axial and radial directions, and the abutment shoulders 96 are arranged at the corresponding tips 92 .

[0042] The tip end 92 and the socket end 94 have such an axial length that electric heating devices 22 having different thicknesses can be arranged between the fluid housing 10 and the housing bottom 14 without destroying the seal between the housing base 4 and the fluid housing 10. As a result, the inlet flow connection ES formed by the inlet channel segments 84, 86 can vary in length transverse to the plane E containing the electric heating device 22. The same applies to the outlet flow connection marked with the reference AS.

[0043] The fluid flow introduced into the electric heating device 2 through the inlet 58 is divided into two partial flows in the region of the distributor 62. The first partial flow T1 flows into the first heating chamber 6.1 via the overflow edge 72, while the second partial flow T2 runs through the inlet flow connection ES, flows through the second heating chamber 6.2, that is, first through the inlet branch 68, then through the outlet branch 70, and finally through the outlet flow connection AS, merges with the first partial flow T1 in the region of the distributor 62, and the fluid flow resulting from the combination of the two partial flows T1, T2 is discharged through the outlet.

[0044] Figure 4 The electrical connection principle of the circuit board 38 is also shown. The contact tongues 202 of the male plug contacts 204 protrude into the mounting plane of the circuit board 38, which can be identified by the support 200 of the circuit board 38, and are exposed at the free end of the plug (only the power plug 46 is shown) or at the free end of the connecting tab 206 of the negative contact or at the free end of the connecting tab 208 of the positive contact. After assembly, the connecting tabs 206, 208 also protrude beyond the fluid housing 10 arranged below the assembly level of the circuit board 38. The circuit board 38 can be plug-connected to all the contact tongues 202 by simply lowering it in the direction of the housing bottom 14, i.e. in a direction perpendicular to the flat extension of the housing bottom 14. The assembled circuit board 38 is placed on the support 200 and is fixed by means of screws 220 (at the bottom of the support 200) which engage with the thread of the support 200. Figure 5 and Figure 6 ) is fixed relative to the housing base 2.

[0045] about Figure 6 , reference may be made essentially to the previous description. In particular, identical components are provided with the same reference numerals and have the same function.

[0046] On the one hand, according to Figure 6 The embodiment of is characterized by a different arrangement of the plugs 46, 48. Figure 7 , reference numeral 222 denotes a grounding bolt for connecting the housing 44 to a grounding post.

[0047] In various embodiments, separate connection housings 224 made of electrically insulating material protrude from the underside of the circuit board 38. The connection housings each form a chamber 226 for one polarity that is electrically isolated from one another.

[0048] Reference numeral 230 denotes a pressing member made of synthetic material, which has a substantially triangular base. The triangular base of the pressing member 230 forms a wide side 232 and a narrow side 234. Fixing holes 236 are formed on the wide side 232. Corresponding fixing holes 236 are arranged on the opposite narrow side. These fixing holes 236 form a positioning receiving portion 240. Figure 8 A plurality of compression elements 242 are shown, which protrude from the underside of the illustrated pressure piece 230 from a pressure piece carrier 243 and are made of a soft, elastic synthetic material, while the pressure piece carrier 243 itself is made of a hard synthetic material. In the present case, the compression elements 242 are connected by overmolding with the hard synthetic material of the pressure piece 230 and thus by composite injection molding (also called multi-component injection molding).

[0049] Corresponding to these compression elements, Figure 6 The openings marked with reference numeral 42 are omitted on the side of the circuit board 38 in the circuit board 38, the openings penetrate the circuit board 38 and omit the power switches arranged on the lower side facing the fluid housing 10. These power switches are Figure 6 It is schematically marked with reference numeral 246.

[0050] like Figure 7 As shown, the screw 220 not only passes through the fixing hole 236, but also passes through the positioning hole 250 in the circuit board 38, more precisely, on the narrow side 234 and the wide side 232. Only one screw 220 and one fixing hole 236 are provided on the narrow side 234, and three corresponding configurations are provided on the wide side 232.

[0051] from Figure 7 and Figure 8 As can be seen from the overall view, the compression element 242 is assigned to the wide side 232. In a corresponding manner, the power transistor is arranged above the base surface of the fluid housing 10, but close to its longitudinal edge. The wide side 232 and the narrow side 234 protrude beyond the base surface of the fluid housing 10. A more secure mechanical connection between the pressing piece 230 and the side thereof acting on the power switch 246 is achieved by a plurality of screws 220. Therefore, the screw 220 is an example of a positioning element 252, which is designed as a positioning pin 254 in this case, which penetrates the positioning hole 250 in the circuit board 38 with a small clearance and positions the circuit board 38 accordingly relative to the housing 44, in particular relative to the pressing piece 230. Each compression element 242 is reliably engaged in the opening 244 assigned to the compression element in the circuit board 38, and thus acts on the power switch 246.

[0052] Furthermore, the pressing piece 230 is supported by screwing the screw 220 into the associated thread 83 of the housing base 4. The circuit board 38 itself is supported via the further screw 220 and the support 200. Since the compression element 242 protrudes through the opening 244, the circuit board 38 is not subjected to pressure.

[0053] Reference numerals list

[0054] 2 Electric heating equipment

[0055] 4 Shell base

[0056] 6.1 First Heating Chamber

[0057] 6.2 Second Heating Chamber

[0058] 8 Heating chamber cover

[0059] 10 Fluid housing

[0060] 12 Accommodation Space

[0061] 14 Shell bottom

[0062] 16 Surrounding wall

[0063] 18 First insulation layer

[0064] 20 First contact connection layer

[0065] 22 Heating device

[0066] 23 Heating element

[0067] 24 PTC components

[0068] 26 Positioning frame

[0069] 28 Accommodation

[0070] 30 second contact connection layer

[0071] 32 Second insulation layer

[0072] 33 Preload device

[0073] 34 Hierarchical structure

[0074] 36 Control Device

[0075] 38 Circuit Board

[0076] 40 transistor insulation

[0077] 42 Shell cover

[0078] 44 Shell

[0079] 46 Power plug

[0080] 48 control plug

[0081] 50 Inlet Port

[0082] 52 egress port

[0083] 53 Sealing structure

[0084] 54 Sealing ring

[0085] 56 Screws

[0086] 58 Entrance

[0087] 60 Exit

[0088] 62 Distributor

[0089] 64 Inlet distributor segment

[0090] 66 Outlet distributor segment

[0091] 68 Entrance Branch

[0092] 70 Exit Branch

[0093] 72 Overflow Edge

[0094] 74 first heating chamber bottom

[0095] 76 guide ribs

[0096] 78 Fluid housing base

[0097] 80 Fluid housing cover

[0098] 82 fixing holes

[0099] 83 Thread

[0100] 84 First entrance passage section

[0101] 86 First exit channel segment

[0102] 88 Second entrance passage section

[0103] 90 Second exit channel segment

[0104] 92 Tip

[0105] 94 socket end

[0106] 96 against shoulder

[0107] 200 Support

[0108] 202 tongue contact

[0109] 204 Male plug contacts

[0110] 206 Negative contact connection flag

[0111] 208 Connection flag for positive contact

[0112] 220 Screw

[0113] 222 Grounding bolt

[0114] 224 Connecting shell

[0115] 226 Chamber

[0116] 230 Pressing piece

[0117] 232 Broadside

[0118] 234 Narrow Edge

[0119] 236 Fixing holes

[0120] 240 Positioning and accommodating portion

[0121] 242 Compression element

[0122] 243 Press piece carrier

[0123] 244 Opening

[0124] 246 Power Switch

[0125] 250 Positioning hole

[0126] 252 Positioning elements

[0127] 254 Locating pin

[0128] AS Outlet Stream Connection

[0129] ES Inlet Stream Connection

[0130] E plane containing the electric heating device

[0131] HE plane containing the first heating chamber

[0132] L Longitudinal axis

[0133] T1 First shunt

[0134] T2 Secondary shunt

Claims

1. An electric heating device (2), comprising: Electric heating device (22); A control device (36) is designed to control an electric heating device (22) and has at least one power switch (246) that generates power loss; and a housing base (4) designed to accommodate the control device (36), the housing base being connected to a housing cover (42) to form a housing (44) that is sealed relative to the environment, and the housing base at least partially forming a heating chamber (6.1) or accommodating the heating chamber (6.2) in itself, the power switch (246) being connected to the heating chamber in a heat-conducting manner, The invention is characterized in that a pressing piece (230) is arranged in a housing (44), the pressing piece is arranged on the side of the heating chamber (6.2) opposite to the control device (36) and is connected to the housing base (4), and the pressing piece keeps the power switch (246) pre-tensioned in the direction of the heating chamber (6.2).

2. The electric heating device (2) according to claim 1, characterized in that: The positioning element extends from a housing bottom (14) formed by the housing base (4), passes through a positioning hole (250) in a circuit board (38) of a control device (36) that electrically connects a power switch (246), and is accommodated in a positioning accommodation portion (240) of a pressing piece (230).

3. The electric heating device (2) according to claim 1 or 2, characterized in that: At least one of the positioning elements (252) is formed by a positioning pin (220) which can be connected to the housing base (14) and / or the pressure piece.

4. An electrical heating device (2) according to any one of the preceding claims, characterized in that The heating chamber (6.2) is arranged in the housing (44) between a housing bottom (14) formed by the housing base (4) and a circuit board (38) of a control device (36) which electrically connects a power switch (246).

5. The electric heating device (2) according to claim 4, characterized in that: The power switch (246) is arranged on a side of a circuit board (38) of the control device (36) that electrically connects the power switch (246) and faces the heating chamber (6.2), and the circuit board (38) has an opening (244) for transmitting the preload applied by the pressing piece (230) to the power switch (246).

6. The electric heating device (2) according to claim 5, characterized in that: The opening (244) is penetrated by an elastic compression element (242), which is arranged under preload between the pressure piece (230) and the power switch (246).

7. The electric heating device (2) according to claim 6, characterized in that: The pressure piece (230) has a pressure piece carrier (243) formed from a hard plastic material, and the compression element (242) is connected to the pressure piece carrier (243) by overmolding.

8. An electrical heating device (2) according to any one of the preceding claims when dependent on claim 3, characterised in that The control device (36) has a plurality of power switches (246) arranged adjacent to each other, the power switches (246) being arranged adjacent to the edge of the heating chamber (6.1), the pressing piece having a wide side (232) on the side of the power switch (246) and a narrow side (234) opposite to the wide side, the wide side (232) and the narrow side (234) protruding from the heating chamber (6.1) and being respectively connected to the housing base (4), and the wide side (232) being assigned to the power switch (246), and more positioning pins (220) being arranged on the wide side than on the narrow side (234).

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