Heating Cell and PTC Heating Device Comprising Such

Abstract

A heating cell includes a frame made of electrically insulating material. A PTC element, which is received in a frame opening of the frame. Insulating layers accommodate the PTC element between themselves, are connected to the frame, and at least partially cover a respective main side surface of the PTC element exposed in the frame opening and a frame surface defining the frame opening. Abutment projections project beyond the frame surface and at least partially enclose a circumferentially encircling edge of the insulating layer between themselves.

Claims

1. A heating cell comprising: a frame which is made of electrically insulating material; a PTC element which is received in a frame opening of the frame; insulating layers which accommodate the PTC element between themselves, which are connected to the frame, and by which a respective main side surface of the PTC element that is exposed in the frame opening and a frame surface that defines the frame opening are at least partially covered; wherein the frame has abutment projections that project beyond the frame surface and that at least partially enclose a circumferentially encircling edge of each of the insulating layers between themselves.

2. The heating cell according to claim 1, wherein two abutment projections are associated with a corner of the insulating layer and are provided and enclose the insulating layer between themselves on oppositely disposed sides of the corner.

3. The heating cell according to claim 2, wherein an adhesion chamber is formed between the two abutment projections, wherein the adhesion chamber is defined on an inside thereof by the insulating layer and on an outside thereof by a connection segment located between the abutment projections, and wherein an adhesive that connects the insulating layer to the frame is received in the adhesion chamber.

4. The heating cell according to claim 3, wherein the adhesive is cured by UV rays.

5. The heating cell according to claim 1, wherein the abutment projections do not project beyond the insulating layers in a thickness direction of the insulting layers.

6. The heating cell according to claim 3, wherein the connection segment does not project beyond the insulating layers in a thickness direction of the insulating layers.

7. The heating cell according to claim 1, wherein the abutment projection is formed integrally on the frame.

8. The heating cell according to claim 3, wherein the connection segment is formed integrally on the frame.

9. The heating cell according to claim 1, wherein connection lugs project beyond opposite sides of the frame and abut against the PTC element in an electrically conductive manner for energizing the PTC element with different polarities, and wherein each insulating layer forms a respective connection lug receiving chamber which is recessed relative to an abutment surface of the insulating layer, with which the insulating layer abuts in a planar manner against the PTC element, and which is adapted to receive one of the connection lugs.

10. The heating cell according to claim 9, wherein each connection lug is formed by a piece of sheet metal forming at least one spring tongue which is formed integrally on the connection lug and which abuts against the PTC element subject to bias and which is held by the abutment of the connection lugs against the insulating layer.

11. The heating cell according to claim 9, wherein each connection lug is formed by a piece of sheet metal forming at least one latch tongue which is formed integrally on the connection lug and which is received in a latch receptacle formed by the frame.

12. A PTC heating device comprising: a casing that encloses a PTC heating cell, the PTC heating cell including a frame made of electrically insulating material; a PTC element which is received in a frame opening of the frame; insulating layers which accommodate the PTC element between themselves, which are connected to the frame, and by which a respective main side surface of the PTC element that is exposed in the frame opening and a frame surface that defines the frame opening are at least partially covered; wherein the frame has abutment projections that project beyond the frame surface and that at least partially enclose a circumferentially encircling edge of the insulating layer between themselves, wherein the casing encloses the PTC heating cell in such a way that the insulating layers each abut in a planar manner against an inner surface of the casing and the abutment projections do not project beyond the insulating layers associated with them in a thickness direction of the insulation layers, and wherein the casing has connection lugs projecting beyond itself which abut on oppositely disposed sides against the PTC element in an electrically conductive manner for energizing the PTC element with different polarities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further details and advantages of the present invention shall become apparent from the following description of an embodiment in combination with the drawing, in which:

[0025] FIG. 1 shows an exploded view of the embodiment of a heating cell;

[0026] FIG. 2 shows a top view onto the embodiment according to FIG. 1 after all components have been assembled;

[0027] FIG. 3 shows an enlarged detail of a corner according to the illustration of FIG. 2;

[0028] FIG. 4 shows an upper top view onto the heating cell; and

[0029] FIG. 5 shows a sectional view along the line V-V according to FIG. 2.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a perspective exploded view of the components of an embodiment of a heating cell with a frame 2 which comprises oppositely disposed frame surfaces 4 that define an edge to a frame opening 6 and that each comprise four surface segments extending orthogonally to one another. Abutment projections 8 project in the region of the corners from the frame surface 4. Two such abutment projections 8 are provided for each corner. A connection segment 10 extends in each corner between these abutment projections 8 and bridges the corner of the frame 2 and directly adjoins the abutment projections 8. An adhesion chamber 12 is formed at each corner between the abutment projections 8 provided in pairs of each corner and surrounded on the outside by the connection segment 10.

[0031] Reference numeral 14 in FIG. 1 denotes a PTC element which fits into the frame opening 6 and can accordingly be arranged between the frame surfaces 4. Reference numeral 16 denotes insulating layers which on the outside form a flat outer surface of the heating cell and on the inside likewise have a flat abutment surface for direct contact with the PTC element 14, which abutment surface, however, being interrupted in the upper region by a connection lug receiving chamber 18 which is stepped in the direction toward the outer surface and is formed to be adapted to receive one of the connection lugs denoted by reference numeral 20.

[0032] These connection lugs 20 presently each have two spring tongues 22 which by punching and bending project from the plane of the sheet metal material forming the connection lug 20 in the direction towards the PTC element 14 and can be abutted in a resilient manner against the PTC element 14. A latch tongue 24 formed by punching and bending projects in the same direction from the sheet metal material of the connection lug. In an installed position, webs 26 abut on the upper side against a receiving box 28 which is formed integrally on the frame 2 and forms a latch opening 30 for receiving the latch tongue 24. The receiving boxes 28 each have a longitudinal slot 32 which is adapted to receive the connection lug 20 and, in the assembled state, is aligned with the connection lug receiving chamber 18 (cf. FIG. 4).

[0033] To assemble the heating cell, one of the insulating layers 16 is first abutted against the frame surface 4 of the previously injection-molded frame 2. UV-curing adhesive is then introduced into each of the adhesion chambers 12. In the embodiment shown, this adhesive bonds in the region of adhesion surfaces which are denoted by reference numeral 34 in FIG. 3. Each of the four corners in the embodiment is respectively provided with an adhesion chamber 12 on each of the frame surfaces 4. However, it is also considered sufficient for attaching the insulating layer 16 to the frame 2 to form abutment projections 8 with associated connection segments 10 and therefore adhesion chambers 12 only at diagonally oppositely disposed corners. As illustrated in FIG. 2, the insulating layer 16 then is disposed entirely over the main side surface of the PTC element and covers the frame surface 4 at least in part.

[0034] The sectional view according to FIG. 5 illustrates that the abutment projection 8 and the connection segment 10 do not project beyond the insulating layer 16 in the thickness direction. The outer surface of the heating cell extending parallel to the main side surface of the PTC element 14 is accordingly formed by the outer surface of the insulating layers 16.

[0035] After the insulating layer 16 has been applied on one side and connected to the frame 2, the PTC element 14 is introduced into the frame opening 6 which is now closed on the underside. The other insulating layer 16 is then applied thereafter from the oppositely disposed side, as described above, and adhesively bonded to the frame 2.

[0036] Thereafter, the connection lugs 20 are typically introduced via the longitudinal slots 32 into the connection lug receiving chambers 18 associated with the former. The heating cell preassembled in this manner can be handled as an integral component and introduced into a casing of a PTC heating device. This casing can be a sheet metal sleeve which abuts, subject to resilient expansion, against the outer surface of the heating cell when the PTC heating cell is introduced, so that good heat transfer to the outer side of the casing is created. Alternatively, the casing can also be deformed after the heating cell has been introduced, so that the casing is also abutted without an air gap and/or adhesive against the outer surfaces of the heating cell in the main direction of extension of the PTC element 14.

[0037] If necessary, the heating cell can also be inserted into a wedge element which can be inserted into a casing in the form of a heating rib and braced there so that good heat dissipation from the heating cell into a heating chamber is possible.

[0038] The example of a PTC heating cell shown in the figures can be exposed in a casing within this casing in a heating chamber for heating a fluid. Such a casing made of elongate tubular sheet metal material can be gathered, for example, from EP 3 273 177 A1. The heating cell according to the invention can also be used in an electrical heating device produced in such a way.

[0039] The heating cell can also be introduced into an envelopment as is known from EP 2 440 004 A1. Such an envelopment projects from a partition wall which separates a connection chamber from a heating chamber. The envelopment is typically formed to be wedge-shaped and the receptacle for the heating cell then also has outer walls that run at an angle to one another. The aforementioned heating cell can be introduced, for example, into a housing that forms wedge surfaces which together with the housing directly contact the inner surfaces of the receptacle in a thermally conductive manner after the heating cell has been introduced. Finally, it is also possible to surround the previously mentioned heating cell with a frame made of an insulating plastic material according to EP 3 101 364 A1 which by itself forms the above-mentioned partition wall or is plug-connected thereto. The heating cell can also be received in a sleeve-shaped casing closed on the underside, where the end of this casing, beyond which the connection lugs project, is provided with a sealing collar which is received in a plugged manner sealed in a plug-in receptacle which is recessed in the partition wall, as is described in DE 20 2019 005 220.