EP3873174B1 - Electric heating device and method for its production - Google Patents

Description

The present invention relates to an electric heating device with a housing which has a partition wall which separates a connection chamber from a heating chamber for dissipating heat. At least one PTC heating device protrudes from the partition in the direction of the heating chamber. This PTC heating device is exposed in the heating chamber in the manner of a heating rib. The PTC heating element has at least one PTC element and conductor tracks connected thereto in an electrically conductive manner, which are assigned different polarities for energizing the PTC element. These conductor tracks are electrically connected to the power current in the connection chamber.

Such a heater is off, for example EP 1 872 986 A1 or EP 2 337 425 A1 known. Another electric heater of the same generic type is off EP 3 334 242 A1 known. In this prior art, the PTC heating element is first produced as a separate component and as such is inserted into a heating element mount formed on the partition wall, so that the end of the heating element housing on the connection side is sealed in the heating element mount of the partition wall and the conductor tracks with their free, connection-side ends are exposed in the connection chamber in order to be electrically connected there.

In the prior art mentioned above, the PTC heating element preassembled in this way is held in the heating element receptacle by friction. For this purpose, the PTC heating element has a labyrinth seal formed by the heating element housing, which is pressed into the heating element receptacle.

According to the teaching of EP 3 334 242 A1 should the attachment of the PTC heating element be suitable at least for the assembly of the individual components of the previously known electrical heating device. After the assembly of all components of the electrical heating device, the PTC heating element is supported on its underside opposite the connection side on a base, which closes off the heating chamber in the previously discussed example. In this way, the PTC heating element is clamped between the floor and the heating element holder and secured in its installation position.

DE 20 2019 005223 discloses an electric heater according to the preamble of claim 1.

The present invention is based on the problem of specifying an electric heating device that is improved with regard to the sealing of the PTC heating device and a method for producing such a heating device.

In order to solve the device-related problem, an electric heating device with the features of claim 1 is specified with the present invention.

In this electrical heating device, the heater housing is sealed off from the receptacle with a seal, as is known per se from the prior art. The seal surrounds the heater housing. The receptacle thus forms a female plug-in element of a mechanical coupling of the heater housing together with the seal. The seal can be connected to the heater housing in a manner known per se before the heater housing is installed on the partition, in particular by injection molding an elastomeric plastic materially connected to the heater housing. Alternatively, the seal can also be manufactured separately and inserted in a form-fitting manner in a seal receptacle formed on the heater housing.

The seal consists of a flexible plastic, usually elastomer, the seal is particularly preferably made of silicone.

According to the present invention, a press ring is arranged in the socket, which press ring surrounds the circumference of the heater housing and secures the seal in the socket. The press ring is pressed into the receptacle and is thereby pressed between the heater housing and a wall of the partition that defines the receptacle. The pressing ring can be held in a form-fitting and/or force-fitting manner. The press ring thus secures the heater housing in the receptacle and prevents the seal from becoming detached from the receptacle.

Ideally, both the heater housing and the seal are secured in the receptacle with the press ring. For this purpose, the compression ring can be located between the seal and the heating chamber and accordingly prevent the seal from slipping out of the receptacle in the direction of the heating chamber. Alternatively, the seal with the press ring can also be designed as a single component. In this case, the compression ring is embedded in the material of the seal when the seal is manufactured. In the direction of insertion of the heater housing into the receptacle, the area of the press ring can be provided at the rear end of this unit made up of press ring and seal, whereas the elastomeric material of the seal is provided at the front end without an inserted press ring and alone effects the seal.

The press ring can have a metallic structure. The compression ring is preferably designed to be electrically conductive. In this case, the press ring rests in an electrically conductive manner against the outer peripheral surface of the heater housing and the inner peripheral surface of the receptacle. By the heater housing around the PTC element and the contact plates formed shielding is thus electrically conductively connected to a shield that includes the partition and shields control components inside the connection chamber. Accordingly, the heater housing is electrically connected via the compression ring to a ground pole of the housing, which is used to shield the electrical heating device as a whole. The ground pin is exposed on the outside of the electric heater for connection of a ground wire. It is usually a bolt which is electrically conductively connected to a part of the heater housing, in particular that part which surrounds the connection chamber.

Improved heat conduction between the heater housing and the housing is also created by the compression ring. In the area of the receptacle, the heat from the heater housing is accordingly dissipated in an improved manner directly to the housing, which in this respect can make a greater contribution to heat extraction than in the prior art. The thermal entry into control electronics that are separated by the partition wall and placed beyond the receptacle is also reduced.

The compression ring is preferably secured in the receptacle by caulking the housing. For this purpose, the areas surrounding the receptacle, which are formed by the housing, are caulked, so that the walls of the receptacle, which are initially cylindrical before assembly and extend in the direction of insertion of the heater housing, are shaped inwards at their free end, so that they form the compression ring and/or protrude beyond the seal. Accordingly, the partition wall in the wall of the receptacle is plastically deformed during caulking. The plastic deformation can be a cold deformation, in particular if the partition wall is made of a metallic material. However, the deformation can also be a hot deformation. This procedure is to be preferred in particular in the case of a dividing wall made of plastic. The respective effective temperature simplifies the plastic deformation of the plastic.

To complete the shielding, a connection bolt is usually provided in the area of the receptacle in such a configuration, which is electrically contacted with the compression ring after assembly in order to electrically connect the shielding provided by the heater housing around the PTC element with a shielding of the electrical heating device . This shielding can be formed, for example, by a shielding housing placed in the connection chamber or by a metallic connection or control housing surrounding the connection chamber.

According to a preferred development of the present invention, the compression ring has a plurality of contact projections which protrude on its outer peripheral surface and usually extend in the direction of insertion. These projections dig into the inner peripheral surface of the wall of the receptacle and bring about a secure connection between the compression ring and the receptacle.

The press ring located in the receptacle improves the retention of the gasket and accordingly improves the sealing between the heater housing and the partition. This reliably prevents a fluid located in the area of the heating chamber from spilling over into the connection chamber. This results in increased electrical safety, in particular when operating the electrical heating device with high voltage, for example in an electrically operated motor vehicle. The field of application of the electrical heating device is in particular in the field of motor vehicle technology. An electric heater installed in a motor vehicle is subject to considerable vibration. Due to the additional securing of the seal in the receptacle with the press ring, the electrical heating device is designed to be vibration-resistant to an increased extent.

To solve the procedural problem, a method with the features of claim 7 is specified with the present invention. A preferred development of the method is specified in claim 8.

Fig. 1

eine perspektivische Explosionsdarstellung des Ausführungsbeispiels der elektrischen Heizvorrichtung;

Fig. 2

eine Längsschnittansicht der PTC-Heizeinrichtung (des Ausführungsbeispiels ohne Dichtung;

Fig. 3

eine perspektivische Seitenansicht eines Details der elektrischen Heizvorrichtung vor dem Fügen der PTC-Heizeinrichtung;

Fig. 4

das Detail gemäß Fig. 3 in einer vergrößerten Ansicht beim Fügen der PTC-Heizeinrichtung;

Fig. 5

eine Ansicht gemäß Fig. 4 am Ende des Fügens der PTC-Heizeinrichtung, die noch in dem Setzwerkzeug aufgenommen ist;

Fig. 6

eine Ansicht Fig. 4 oder 5 nach dem Fügen der PTC-Heizeinrichtung nach dem Entfernen des Setzwerkzeugs;

Fig. 7

eine perspektivische Seitenansicht der PTC-Heizeinrichtung nach dem Verstemmen und

Fig. 8

eine Draufsicht auf die PTC-Heizeinrichtung nach dem Verstemmen.

Further details and advantages of the present invention result from the following description of an exemplary embodiment in conjunction with the drawing. In this show:

1

an exploded perspective view of the embodiment of the electric heater;

2

a longitudinal sectional view of the PTC heater (the embodiment without seal;

3

a perspective side view of a detail of the electrical heating device before joining the PTC heating device;

4

the detail according to 3 in an enlarged view when joining the PTC heating device;

figure 5

a view according to 4 at the end of the joining of the PTC heating device, which is still accommodated in the setting tool;

6

a view Fig. 4 or 5 after joining the PTC heating device after removing the setting tool;

7

a perspective side view of the PTC heating device after caulking and

8

a plan view of the PTC heater after caulking.

the figure 1 12 shows an exemplary embodiment of an electrical heating device 100 with a multi-part housing, which comprises a lower housing part 102 made of plastic and an upper housing part 104 made of metal in one piece by means of die casting.

The lower housing part 102 is trough-shaped and encloses a heating chamber 106 for which inlet and outlet connectors 110 projecting from a floor 106 are provided.

Between the upper housing part 104 and the lower housing part 102 is in the figure 1 a multiplicity of PTC heating devices 112 are shown, which have a PTC element 113 within a heater housing 111 which is closed on the circumference and on the underside and is electrically connected to it, which has conductor tracks 115, cf. Figure2 . The conductor tracks 115 are electrically connected via contact tongues 114 . The PTC heating devices 112 are held with plug-in contacts in receptacles 116 provided for this purpose in a partition wall 117 of the upper housing part 104 . A seal 119 is also provided in this receptacle 116 , which surrounds the heater housing 111 and is pressed into the receptacle 116 .

Details of this embodiment are in the applicant's EP 3 334 242 A1 described.

Further elements of the heating device 100 are shown between the lower housing part 102 and the upper housing part 104 . Reference number 118 denotes a high-voltage plug-in element, which is screwed to the lower housing part 104 and has contact elements protruding into a connection chamber 120 of the upper housing part 104 . These contact elements are electrically connected to a printed circuit board identified by reference number 122, which can be accommodated in the trough-shaped upper housing part 104. Reference number 124 denotes a seal which seals the lower housing part 102 in relation to the upper housing part 104 and thus the heating chamber 106 .

A contacting device 130 is arranged above the upper housing part 104 and below the printed circuit board 122, which electrically connects all contact tongues 114 and groups individual PTC heating devices 112 into heating circuits. An electrical connection is established between the contacting device 130 and the printed circuit board 122 via contact tongues 132 protruding from the contacting device 130 . Connected to the printed circuit board 142 and projecting therefrom is shown at 134 a control signal plug. This control signal plug-in element 134 is screwed against the circuit board 122 .

A further circumferential seal 136 and a control housing cover 138 are shown above the printed circuit board 122, through which the connection chamber 120 of the upper housing part 104 is covered and sealed. The control housing cover 138 is made of metal in order to shield together with the upper part 104 of the housing from electromagnetic radiation which is produced within the control housing 104, 136, 138 as a result of the switching of the power current. Between the control housing cover 138 and the printed circuit board 122 there is a supporting framework 140, which supports compression elements 142 between itself and the printed circuit board 122 in order, for example, to press power transistors mounted on the printed circuit board 122 against cooling surfaces which are thermally conductively connected to cooling domes extended into the heating chamber 106. The cooling surfaces are thermally connected to the power transistors.

After assembly, connecting rods 144 engage behind locking projections 145 which are provided on the lower housing part 102 and the upper housing part 104 in order to connect the two parts 102, 104 to one another in a form-fitting and captive manner. Details are in the EP 2 796 804 A1 described.

The control housing cover 138 forms a control housing 146 together with the upper housing part 104 and the seal 136 . Due to their metallic materials, the control housing cover 138 and the housing upper part 104 form a shield around the control device 148 accommodated in this control housing 146, which is essentially formed by the printed circuit board 122. A connecting bolt 150 protrudes from the control housing 146 in the direction of the plug-in elements 118 , 134 110 . This connection bolt 150 is used to connect the metal control housing 146 to a ground phase and is screwed to the control housing 146 .

The assembly of the PTC heating device 112 in the receptacle 116 results in particular from the following description of FIG Figures 3 to 8 .

while showing 3 an exploded side view with the housing upper part 102, the partition wall 117 forms a plurality of receptacles 116 into which the PTC heating devices 112 are to be inserted. One of the PTC heaters 112 is in 3 shown aligned with a setting tool 200 . As can be seen, the PTC heating device 112 carries the seal 119 which is already mounted on the heater housing 111 .

As 4 can be seen, the PTC heating device 112 is first inserted into the associated receptacle 116 . In the process, the seal 119 is pressed into the receptacle. This alone results in adequate sealing of the PTC heating device 112 in the associated receptacle 116.

The setting tool 200 carries a pressing ring 202 at its front end. This pressing ring 202 is arranged at the front end of the chamber-shaped setting tool 200 . The chamber of the setting tool 200 is designed in such a way that it can basically completely accommodate the heating device 112 (cf. figure 5 ). A mounting tool holder (not shown in detail) for releasably attaching the compression ring 202 is provided with deformation projections 204 directly adjacent to the compression ring 202 counter to an insertion direction marked E. When the setting tool 200 is slipped over the PTC heating device 112 together with the pressing ring 202, the pressing ring 202 is firstly pushed into the receptacle 116 and pressed in in the process. Contact projections 206 provided on the compression ring 202, which extend in the insertion direction E and protrude beyond the otherwise smooth outer peripheral surface of the compression ring 202, dig into the inner wall of the receptacle 116. In the present case, the compression ring 202 is made entirely of metal. Due to the direct contacting of the inner peripheral surface of the receptacle 116, it is in electrical contact with the upper housing part 102. However, it is also in contact with the outer peripheral surface of the heater housing 111 after it has been pressed into the receptacle 116. By pressing in the pressing ring 202, electrical contact is made between the heater housing 111 and the housing upper part 102 causes. Accordingly, the heater housing 111 is electrically integrated into the shielding of the upper part of the housing.

As part of the insertion movement of the setting tool 200, the deformation projections 204 are pressed against the front edge of the receptacle 116, which leads to a plastic deformation of the edges of the receptacle 116. As a result of this caulking, the initially extending exclusively in the insertion direction E and defining the receptacle 116 becomes Material also deformed radially inward and toward heater housing 111. After caulking, parts of the partition wall 117 overlap the press ring 202, which is thus secured in the receptacle 116 in a form-fitting manner.

The corresponding deformation areas are in the Figures 7 and 8 identified as caulking deformations 208. The caulking deformation 208 is deformed downwards in the insertion direction E and also radially inwards relative to the free edge of the receptacle 116, which is identified by reference numeral 210. As can be seen, adjacent receptacles 116 can share a common wall (cf. 6 ), so that when the edge 210 is caulked, a plurality of previously inserted compression rings 202 are secured in a form-fitting manner in the associated receptacle 116 in the manner described above.

Claims (8)

1. Electric heating device (2) comprising a housing (102, 104, 138) with a partition wall (117), which separates a connection chamber (120) from a heating chamber (106) for dissipating heat and from which at least one PTC heating element (112) with a heater casing (111) protrudes in the direction toward said heating chamber (106), in which heater casing at least one PTC element (113) and conductor tracks (115) that are electrically connected in said connection chamber (28) for energizing said PTC element (113) with different polarities and connected to the latter in an electrically conductive manner are supported in an insulated manner and which is sealed against said partition wall (117) by way of a seal (119) arranged in a receptacle (116) of said partition wall (117) circumferentially surrounding said heater casing (111),
   characterized by
   a press ring (202) arranged in said receptacle (116) and circumferentially surrounding said heater casing (111) and securing said seal (119) in said receptacle (116).
2. Electric heating device according to claim 1, characterized in that said PTC element (113) and said conductor tracks (115) are received in a shielded manner in said heater casing (111) and that said press ring (202) is electrically conductive and connects said heater casing (111) electrically to a ground terminal of said housing (102, 204, 138).
3. Electric heating device according to claim 1 or 2, characterized in that said press ring (202) and said seal (119) are realized in a unitary component.
4. Electric heating device according to claim 1 or 2, characterized in that said press ring (202) is arranged between said seal (119) and said heating chamber (106).
5. Electric heating device according to one of the preceding claims, characterized in that said press ring (202) is secured in said receptacle (116) by press-fit stemming said housing (102, 204, 138).
6. Electric heating device according to one of the preceding claims, characterized in that said press ring (202) on its outer circumferential surface comprises several contact projections (206) extending in a direction of insertion (E) of said receptacle and abutting at least in part under plastic deformation in said receptacle (116).
7. Method for producing an electric heating device, in which a housing (102, 204, 138) with a partition wall (117) which separates a connection chamber (120) from a heating chamber (106) for dissipating heat and at least one PTC heating device (112) with a heater casing (111), in which heater casing at least one PTC element (113) and conductor tracks (115) that are supported in an insulated manner in said heating element housing (111) for energizing said PTC element (113) with different polarities and connected to the latter in an electrically conductive manner are first produced, and said PTC heating device (112) is introduced into a receptacle (116) of said partition wall (117) such that it protrudes from said partition wall (117) in the direction toward said heating chamber (106), characterized in that a press ring (202) is introduced into said receptacle (116) and secured in position in said receptacle.
8. Method according to claim 7, characterized in that said press ring (202) is secured in position by press-fit stemming said housing (102, 204, 138).

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