Electric heating device

Abstract

The invention relates to an electric heating device (2), in particular for a motor vehicle, having a housing (44), which encloses a heating chamber (6.1, 6.2), which is connected to an electrically resistive element (23) in a heat-conducting manner, and which encloses a control device (36). The electric heating device (2) also has a pressure equalizing device (58) for equalizing a pressure difference between the interior of the housing (44) and the environment of the housing (44), which pressure equalizing device is sealingly inserted into a receiving bore (62) formed to receive the pressure equalizing device (58) and recessed into the housing (44).

Description

Technical Field

[0001] The invention relates to an electric heating device. Background Art

[0002] The electric heating device known from EP 3 334 242 A1 is considered to be of the same type.

[0003] In the above-mentioned prior art, the electric heating device has a control housing that is connected to plug-in contacts with contact elements for the supply current or to plug-in contacts with contact elements for control signals via corresponding interfaces. These interfaces also allow gas exchange between the interior of the housing and the environment, thereby achieving pressure equalization. Summary of the Invention

[0004] Based on this, the present invention seeks to provide an electric heating device that can be adapted to different requirements in an improved manner.

[0005] In order to solve this problem, the present invention proposes an electric heating device having the features of claim 1. The electric heating device differs from the above-mentioned prior art in that it includes a pressure equalization device for equalizing the pressure difference between the interior of the housing and the environment of the housing, and the pressure equalization device is inserted in a sealing manner into a receiving hole formed in the housing and suitable for receiving the pressure equalization device.

[0006] In the electric heating device according to the present invention, the housing is typically made of metal, at least partially surrounding the control device. The housing has a receiving hole that extends through the housing wall and thus connects the interior of the housing (particularly the portion of the housing that receives the control device) to the environment. This receiving hole is particularly suitable for accommodating a pressure equalization device. Therefore, the dimensions of the mounting hole are precisely adapted to accommodate the pressure equalization device. The pressure equalization device generally serves only to equalize the pressure difference between the interior of the housing and the surrounding environment.

[0007] In this way, the electric heating device according to the invention enables pressure equalization between the interior and the exterior, for example due to temperature changes.

[0008] According to a further preferred development of the present invention, the pressure equalization device is screwed into the receiving hole. To this end, the pressure equalization device, in particular its pressure equalization plug, is typically provided with an external thread, and the receiving hole is provided with an internal thread. Alternatively, the pressure equalization device can be mounted in the positioning hole in the form of a clip. To this end, the pressure equalization plug can be inserted into the positioning hole and provided with a locking tab on its underside, for example, which protrudes into the housing.

[0009] The pressure-equalizing plug is preferably penetrated by a pressure-equalizing channel, which typically extends centrally within the receiving opening in its longitudinal direction and is sealed by a gas-permeable, water-impermeable device. This device serves to retain moisture, particularly water in liquid or vapor form. This device can be made of metal or plastic, in particular as a membrane that provides differential permeability to gas and moisture. This property can also be provided by a filter made of plastic, natural materials (such as cellulose fibers), and / or metal.

[0010] The device is preferably arranged on the outside of the pressure-compensating plug and is particularly preferably connected to its front portion. To this end, the pressure-compensating plug preferably has a radial flange that is wider than the remainder of its outer diameter. The device can be applied to the front portion of this flange, particularly in the form of a diaphragm, and connected to it by a material bond. On the side opposite the device, a sealing ring is typically located between the radial flange and the housing, by which the pressure-equalizing device is sealed relative to the housing.

[0011] As an alternative to a separate sealing ring, it is also possible to form the seal as an integral part of the pressure compensation plug, for example by overmolding the pressure compensation plug with a soft, elastic plastic.

[0012] The diaphragm can be flexible so that it can compensate for certain pressure fluctuations within the control housing through elastic deformation. However, it is preferably air-permeable and water-tight, allowing air to escape from the control housing in the event of any overpressure or to flow into the control housing through the diaphragm in the event of a certain underpressure, thereby achieving pressure equalization within the control housing. Simple systems with only one diaphragm or multi-part systems with a multilayer membrane structure can be used for ventilation, whereby different layers of the membrane structure can have different functions, such as mechanical or retaining functions. Within the scope of the present invention, sintered filters can also be used as a means for ventilation via the pressure equalization channel.

[0013] The membrane can be welded to the pressure equalizing plug, in particular ultrasonically welded to the pressure equalizing plug.Alternatively or additionally, the diaphragm can be bonded to the pressure equalizing plug.

[0014] It has been found that a gas-permeable, liquid-impermeable membrane made of ePTFE or PTFE is preferred. The membrane should have a thickness between 120 μm and 240 μm, in particular 180 μm ±50 μm. Practical tests by the applicant have shown that such a membrane prevents water or water vapor from entering the control housing, but allows air to escape from the control housing through the membrane.

[0015] A cap is preferably provided on the outside of the housing and typically covers a diaphragm which is connected, preferably latched or pressed, to the pressure equalizing plug.

[0016] The cap can also be formed integrally on the pressure-compensating plug, for example as a uniform injection-molded component, while retaining the compensation channel within the pressure-compensating plug. In this variant in particular, the diaphragm is preferably located at the end of the pressure-compensating plug that projects into the housing and can be connected to the pressure-compensating plug in the manner described above.

[0017] This cap and / or pressure equalization plug can be made of plastics or metal.It is understandable that between cap and the front opening of pressure equalization passage, leave the compensation gap that is used for pressure equalization, and this front opening is covered by diaphragm usually.

[0018] The housing is preferably thickened in the region of the positioning opening, so that the positioning opening has a sufficient length for a secure connection to the pressure equalization device, in particular a pressure equalization plug inserted into the positioning opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further details and advantages of the present invention can be seen from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

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

[0021] Figure 2 Shows the pressure equalization device according to Figure 1 an enlarged perspective top view of a portion of a housing;

[0022] Figure 3 Shown along Figure 2 A longitudinal cross-section along line III-III is shown. DETAILED DESCRIPTION

[0023] Figure 1 An electric heating device 2 is shown having a housing base part 4 which is provided at Figure 1 The lower side of the fluid housing 10 is connected to a heating chamber cover (not shown here) to form a first heating chamber 6.1. Reference numeral 10 denotes a fluid housing, which is accommodated in a receiving space 12 formed by the housing base part 4 and forms a second heating chamber 6.2. In this receiving space 12, which is delimited on the lower side by a base 14 and bordered by a circumferential wall 16 extending from the base 14, and between the base 14 and the fluid housing 10, there are: a first insulating layer 18, which can be placed against the base 14; a first contact layer 20 and a heating device 22, which has a plurality of resistor elements 23, which in this case are in the form of PTC elements 24, and a positioning frame 26, which has a socket 28 for receiving the PTC elements 24.

[0024] A second contact layer 30 is provided on the side of the heating device 22 opposite to the first contact layer 20, and a second insulating layer 32 is arranged on the side of the second contact layer 30 opposite to the heating device 22. Therefore, the PTC element is electrically conductive relative to the contact layers 20, 30, and current is passed through these contact layers. The PTC element 24 is a ceramic rectangular parallelepiped component, which is provided with metallization layers on opposite main side surfaces for current conduction. The main side surfaces are the surfaces with the largest surface area in the rectangular parallelepiped. The main side surfaces are connected to each other by edge surfaces, which determine the height of the PTC element and do not have any metallization layer. The main side surfaces are generally five times larger than one of the edge surfaces, and preferably larger than the sum of all edge surfaces.

[0025] The second insulating layer 32 is formed as a prestressing device 33 by a silicone film, which can absorb a certain compression by elastic deformation, thereby applying the electric heating device 22 between the shell base part 10 and the shell base 14 under prestress, and resting on the shell base part 10 and the shell base 14.

[0026] The layering of the first insulation layer 18 , the first contact layer 20 , the heating device 21 , the second contact layer 30 and the second insulation layer 32 is also referred to below as a layered structure 34 .

[0027] In the illustrated embodiment, a transistor insulator 40 is located between the printed circuit board 38 forming the control device 36 and the fluid housing 10 on the side of the fluid housing 10 facing away from the layered structure 34. Reference numeral 42 designates a housing cover, which is connected to the housing base 4 to form the housing, designated by reference numeral 44. The housing base 4 and the housing cover 42, as well as any other housing components, are shielded, i.e., made of metal and / or provided with separate shielding in the interior, exterior, or walls of the individual housing components, which may be made of plastic. Preferred metal materials are aluminum or stainless steel for corrosion resistance.

[0028] The power connector 46 and the control connector 48 are Figure 1 4 are shown on the lower side of the housing base part 4 opposite the housing cover 42. The two plugs 46, 48 are connected to the housing base part 4 in a sealed manner and have various plug-in electrical plug contacts, which pass through the respective housings of the plugs 46, 48 in a sealed manner and form plug contacts in the printed circuit board 38 and are electrically connected to the conductor tracks of the printed circuit board 38 via the plug contacts. For the plug contacts, the printed circuit board 38 has recessed contact tongue sockets, which are described in EP 2 236 330 A1.

[0029] Furthermore, inlet and outlet nozzles 50, 52 are provided on the underside for connecting pipes or hoses carrying the fluid to be heated. Reference numeral 53 denotes Figure 1 , a sealing device 53 is shown below the fluid housing 10, which in this case is formed by two sealing rings 54. Reference numeral 56 denotes a screw for fixing the fluid housing 10 relative to the housing base part 4, with the layered structure 34 interposed therebetween. This screw connection places the layers of the layered structure 34 against the fluid housing 10 and the base 14 of the housing base part 4 under preload.

[0030] Figure 2 and Figure 3 Detail of the pressure equalization device 58 is shown, which is arranged adjacent to the power connector 46 on the housing base part 4. For this purpose, the housing base part 4 has a protrusion 60, by which the wall thickness of the housing base part 4 is increased (see Figure 3 ). The projection 60 is provided with a receiving hole 62 having an internal thread into which the external thread of the pressure-equalizing plug 64 is screwed. The pressure-equalizing plug 64 is penetrated by a pressure-equalizing channel 66 extending in the longitudinal direction of the receiving hole 62 and has a radial flange 68 disposed on the outer side of the projection 60. This radial flange receives a sealing ring 70 between itself and the end face of the projection 60, thereby sealing the receiving hole 62 outward. On the side opposite the sealing ring 70 and on the free end face of the pressure-equalizing plug 64, a diaphragm 74 is provided as an example of a device 72 for closing the pressure-equalizing channel 66 in a gas-permeable but water-tight manner. In the illustrated embodiment, this diaphragm 74 is welded to the pressure-equalizing plug 64. In this example, the pressure-equalizing plug 64 is made of plastic.

[0031] exist Figure 2 and Figure 3 In FIG. 6 , reference numeral 76 denotes a cap covering the diaphragm, which is connected to the pressure equalizing plug 64. Figure 3 As particularly shown in FIG, an equalization channel 78 is maintained between the outer surface of the pressure equalization plug 64 and the outer surface of the diaphragm 74, this equalization channel extending between an orifice 80 of the pressure equalization channel 66 and the end of the cap 76 facing the protuberance 60. Thus, the cap 76 allows mechanical protection of the diaphragm 74, but at the same time allows pressure equalization between the inside and the outside of the housing 44.

[0032] Reference Signs List

[0033] 2 Electric heating device

[0034] 4 Shell base

[0035] 6.1 First Heating Chamber

[0036] 6.2 Second Heating Chamber

[0037] 10 Fluid housing

[0038] 12 Reception Room

[0039] 14. Bottom cover

[0040] 16 Circumferential wall

[0041] 18 First insulation layer

[0042] 20 First contact layer

[0043] 22 Heating device

[0044] 23 Resistor

[0045] 24 PTC components

[0046] 26 Positioning frame

[0047] 28 sockets

[0048] 30 Second contact layer

[0049] 32 Second insulation layer

[0050] 33 Pre-tensioning device

[0051] 34 Hierarchical structure

[0052] 36 control unit

[0053] 38 printed circuit boards

[0054] 40 Transistor Insulator

[0055] 42 Housing cover

[0056] 44 shell

[0057] 46 Power plug

[0058] 48 plug

[0059] 50 Inlet nozzle

[0060] 52 outlet nozzle

[0061] 53 Sealing device

[0062] 54 sealing ring

[0063] 56 screws

[0064] 58 Pressure equalizing device

[0065] 60 liters of upper part

[0066] 62 mounting holes

[0067] 64 Pressure equalizing plug

[0068] 66 Pressure equalization channel

[0069] 68 radial flange

[0070] 70 sealing ring

[0071] 72 Media

[0072] 74 diaphragm

[0073] 76 blocks

[0074] 78 balanced channels

[0075] 80 Mouth.

Claims

1. An electric heating device (2), in particular an electric heating device for a motor vehicle, comprising a housing (44) enclosing a heating chamber (6.1; 6.2), the heating chamber being coupled to a resistance element (23) in a heat-conducting manner, the housing (44) enclosing a control device (36), the control device comprising a pressure equalization device (58) for equalizing pressure differences between the interior of the housing (44) and the environment of the housing (44), the pressure equalization device (58) being inserted in a sealing manner into a receiving opening (62), the receiving opening being designed to receive the pressure equalization device (58) and being recessed in the housing (44).

2. The electric heating device according to claim 1, wherein: The pressure equalization device (58) is screwed into the receiving bore (62).

3. The electric heating device according to claim 2, wherein: The pressure equalization device (58) has a pressure equalization plug (64) through which a pressure equalization channel (66) passes, which is closed by a gas-permeable but water-impermeable device (72).

4. The electric heating device according to claim 3, wherein: The gas-permeable, water-impermeable device (72) comprises a membrane (74) which is connected to the pressure-compensating plug (64), in particular by a material bond.

5. The electric heating device according to claim 4, wherein: The pressure equalization device (58) has a cap (76) covering the diaphragm (74), the cap being connected to the pressure equalization plug (64).

6. The electric heating device according to any one of claims 4 or 5, wherein: The diaphragm (74) is formed of PTFE and has a thickness between 120 μm and 240 μm, in particular between 150 μm and 190 μm.

7. The electric heating device according to claim 5, wherein: The diaphragm (74) is made of metal.

8. The electric heating device according to claim 1, wherein: The pressure equalization device comprises a sealing ring, wherein the pressure equalization device and the sealing ring are formed integrally.

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