Electric heating device and method for its production

Abstract

An electric heating device includes a housing having a partition wall which separates a connection chamber from a heating chamber for dissipating heat and from which at least one receiving pocket protrudes into the heating chamber as a heating rib. A PTC heating device with at least one PTC element and conductor tracks for energizing the PTC element with different polarities, which are electrically conductively connected to the latter and which are electrically connected in the connection chamber, are received in the housing. The PTC element and at least one of the conductor tracks are received in a heater casing. The heater casing is pressed into the receiving pocket subject to plastic deformation of the heater casing and/or the receiving pocket.

Claims

1. An electric heating device comprising: a housing having a partition wall which separates a connection chamber from a heating chamber for dissipating heat, wherein at least one receiving pocket protrudes into the heating chamber as a heating rib; a PTC heating device received in the housing, the PTC heating device including at least one PTC element and conductor tracks for energizing the PTC element with different polarities, the conductor tracks being electrically connected to the PTC element and being electrically connected in the connection chamber, wherein the PTC element and the at least one conductor track are received in a heater casing, and wherein the heater casing is pressed into the receiving pocket subject to plastic deformation of the heater casing and/or the receiving pocket; and wherein the heater casing is cold-welded to the receiving pocket.

2. The electric heating device according to claim 1, wherein at least one surface of the heater casing abutting against the receiving pocket is convex.

3. The electric heating device according to claim 1, further comprising at least one fixation lip which is formed by an undercut on the heater casing by pressing the heater casing into the receiving pocket, the fixation lip being defined in a thickness direction thereof by oppositely disposed inner surfaces, and being plastically deformed, at least in sections, and abutted against an inner surface of the receiving pocket.

4. The electric heating device according to claim 3, wherein the heater casing comprises two legs and a heater casing bottom connecting the legs to one another so as to form a substantially U- or V-shaped receiving space for the PTC element and the at least one conductor track, and wherein at least one fixation lip is provided on at least one of the legs, or two fixation lips are provided on oppositely disposed sides of the heater casing bottom.

5. The electric heating device according to claim 3, wherein the heater casing comprises two legs and a heater casing bottom connecting the legs to one another so as to form a substantially U- or V-shaped receiving space for the PTC element and the at least one conductor track, and wherein at least one fixation lip is provided on at least one of the legs, and two fixation lips are provided on oppositely disposed sides of the heater casing bottom.

6. The electric heating device according to claim 1, wherein the heater casing comprises an abutment surface which, in a press-in direction thereof, is arranged at a rear end thereof and is adapted for the application of a pressing tool.

7. The electric heating device according to claim 1, wherein the heater casing comprises at least one inwardly facing locking projection.

8. The electric heating device according to claim 1, wherein the heater casing is an extruded heater casing.

9. The electric heating device according to claim 1, wherein the heater casing is a pultruded heater casing.

10. A method for producing an electric heating device, comprising: providing a housing with a partition wall which separates a connection chamber from a heating chamber for dissipating heat and from which at least one receiving pocket protrudes into the heating chamber as a heating rib protrudes; introducing a PTC heating device into a heater casing of the PTC heating device, the PTC heating device including at least one PTC element and conductor tracks for energizing the PTC element with different polarities which are electrically conductively connected to the PTC element; and pressing the heater casing into the receiving pocket subject to plastic deformation of at least one of the heater casing and the receiving pocket; and wherein the heater casing is cold-welded to the receiving pocket.

11. The method according to claim 10, wherein the heater casing is introduced into the receiving pocket in such a way that a heater casing bottom is plastically deformed in the bottom of the receiving pocket.

12. The method according to claim 10, wherein the PTC element and the at least one conductor track are first introduced into the heater casing and the heater casing thus populated then is introduced into the receiving pocket.

13. The method according to claim 12, wherein the heater casing is gripped for insertion by an insertion tool, by which the heater casing is abutted against the PTC element subject to deformation before the heater casing is inserted into the receiving pocket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the present invention shall arise from the following description of embodiments in combination with the drawing, in which:

(2) FIG. 1 shows a perspective side view of an embodiment of an electric heating device with the housing partially removed;

(3) FIG. 2 shows a cross-sectional view of the housing base, identified by reference numeral 102 in FIG. 1, with a first variant of a heater casing which is pressed into a receiving pocket;

(4) FIG. 3 shows a perspective sectional view of the receiving pocket with a second variant of a heater casing prior to being completely introduced into the receiving pocket;

(5) FIG. 4 shows a perspective sectional view of the receiving pocket with a third variant of a heater casing prior to being completely introduced into the receiving pocket;

(6) FIG. 5 shows a perspective sectional view of the receiving pocket with a fourth variant of a heater casing prior to being completely introduced into the receiving pocket;

(7) FIG. 6 shows a perspective sectional view of the receiving pocket with a fifth variant of a heater casing prior to being completely introduced into the receiving pocket; and

(8) FIG. 7 shows the embodiment according to FIG. 6 in a side view with an entire heating rib.

DETAILED DESCRIPTION

(9) FIG. 1 shows a housing 100 of an electric heating device which comprises a bottom element 102, a housing base 104, and a housing cover 106. In the embodiment shown, the housing base 104 forms a partition wall 108 extending parallel to the housing bottom 102 and separating a circulation or heating chamber 110, respectively, from a connection chamber 112. In the embodiment shown, at least the housing base 104 is produced integrally formed from aluminum. Heating ribs 114 protrude from the partition wall 108 in the direction toward the heating chamber 110. These heating ribs are formed to taper conically at an angle of approximately 2.5° towards their fine end and form a receiving pocket 116 with oppositely disposed inner surfaces 118. The interior of the heating rib 114 and the connection chamber 112 are fluidically separated from the heating chamber 110.

(10) Connections presently lead to the heating chamber 110 on oppositely disposed face sides of the housing base 104. These connections are formed as hose or pipe connection ports 120 and protrude on the exterior from the actual wall of the housing base 104. They are used to connect hoses or lines that carry liquid fluid to be heated, which is to be heated in the heating chamber 110.

(11) For this purpose, the receiving pockets 116 are each equipped with PTC heating devices 2. One or more of these PTC heating devices 2 can be inserted one behind the other in the longitudinal direction of the heating ribs 114 into the individual receiving pockets 116.

(12) The essential structure of the PTC heating device 2 for the variants discussed below is basically identical. The PTC heating device 2 has a respective heater casing 4 which comprises oppositely disposed legs 6 which are connected to one another pivotable via a heater casing base 8. The heater casing 4 is open on the side opposite the heater casing bottom 8. It typically has contact plates 10 protruding over itself which directly abut against a PTC element 12 in an electrically conductive manner and form connection lugs 14, formed integrally by punching and bending sheet metal material forming the contact plates 10, as contact strips for the plugged contact of the PTC heating device 2. These connection lugs 14 are shown in FIG. 2. Detailing the connection lugs is dispensed with in the other illustrations according to FIG. 3 et. seqq.

(13) As shown in the sectional view according to FIG. 2, the PTC element 12 is disposed in a circumferentially enclosed receptacle of a positioning frame 16 made of insulating material, of which only the upper and lower frame struts 18, 20 can be seen in FIG. 1. The PTC element 12 typically protrudes in the thickness direction, i.e. a thickness direction of the receiving pocket 116, over the frame struts 18, 20 so that the electrically conductive abutment of the contact plates 10 against the PTC element 12 is not impaired by the positioning frame 16.

(14) On the side opposite the PTC element 12, an insulating layer 22 abuts against the outside of the contact plates 10. This insulating layer 22 is formed integrally and wraps around the positioning frame 16 on the underside.

(15) The elements of the PTC heating device 2 described above are received in the heater casing 4 which is presently formed from aluminum and produced by extrusion and cut to length. The width of this heater casing 4 presently corresponds approximately to the width of the PTC element 12. The width direction extends transverse to the plane of illustration according to FIG. 2. The further dimension of the PTC element 12 that can presently be seen in addition to the thickness is the length. This extension roughly corresponds to the direction of insertion of the PTC heating device 2 into the receiving pocket 116.

(16) The right-hand leg 6 of the heater casing 4 in FIG. 2 is formed to be thickened as compared to the left-hand leg and has an abutment surface 26 which extends substantially transverse to the direction of insertion and which is formed planar and end-to-end over the width of the heater casing 4. Above this abutment surface 26, the right-hand leg 6, like the left-hand leg 6, is formed as a substantially thin and planar plate.

(17) The sectional view shows fixation lips 28 which protrude from the bottom in the width direction, and which protruded further in the transverse direction before the heater casing 4 was inserted into the receiving pocket 116, and were deformed parallel to the inner surfaces 118 during the introduction into the receiving pocket 16. These fixation lips 28 can act like barbs.

(18) The heater casing 4 is plastically deformed in the receiving pocket 116 due to the application of force in a planar manner upon the abutment surface 26. With this plastic deformation, the heating rib 114 can also permanently deform. In any case, a cold weld results due to the plastic deformation. For this purpose, pressure can be applied against the abutment surface 26 with a pressing force between 1400 and 3000 Newtons. The aluminum material of the heater casing 4 then flows and bonds with the inner surfaces 118 of the receiving pocket 116 in a positive substance-fit manner.

(19) The components of the PTC heating device that are received within the heater casing 4, namely the PTC element 12 previously inserted into the receptacle of the positioning frame 16, the contact plates 10 abutting thereagainst, and the insulating layer 22 can typically be introduced as a unit between the legs 6 of the heater casing 4 before the latter is introduced into the receiving pocket 116 and pressed thereinto.

(20) FIGS. 3 to 7 show variants of the heater casing 4. For the remainder, the same components like in the previous description are provided with the same reference numerals. In the representations according to FIGS. 3 to 7, the respective heater casing 4 with the components received therein has not yet been fully inserted into the receiving pocket 116. Instead, it projects in part beyond the partition wall 108.

(21) In the previously discussed embodiment, the heater casing 4 forms legs 6 with planar outer surfaces. These outer surfaces, while diverging, are flat, i.e. planar.

(22) In the variant shown in FIG. 3, the legs 6 are formed to be slightly convex. They have a radius of between 500 and 1000 mm. The fixation lips 28 are dispensed with in this embodiment. Instead of a positioning frame 16, only an electrically non-conductive plastic web 30 is provided between a bottom of the heating rib 114 and the PTC element 12. The abutment surfaces 26 are formed on both sides of the PTC element 12 on the two legs 6. When the pressing force is applied on both sides of the PTC element, the material forming the heater casing 4 flows and therefore a more uniform bond arises between the heater casing and the inner surfaces 118. In addition, the PTC element 12 can be arranged at the center of the receiving pocket 116 so that the same heat dissipation conditions prevail on both main side surfaces of the PTC element 12. The main side surface is that surface which extends in the longitudinal direction and in the width direction of the PTC element 12.

(23) In the variant according to FIG. 4, a plurality of fixation lips 28 is formed disposed opposite the main side surfaces of the PTC element 12. They are confined to the upper region of the PTC element 12. For the remainder, the third variant shown in FIG. 4 corresponds to the second variant according to FIG. 3.

(24) In the fourth variant according to FIG. 5, fixation lips 28 are formed only in the region of the heater casing bottom 8. These fixation lips 28 deform inter alia in the bottom of the receiving pocket 116. Two abutment surfaces 26 are formed there as well. The outer surfaces of the legs 6 are convex.

(25) The variant shown in FIG. 6 combines the variant according to FIGS. 4 and 5.

(26) FIG. 7 shows a view of the entire width extension of the receiving pocket 116 and the PTC heating device 12. At the face side of the PTC heating device, a certain gap to the face side boundary of the receiving pocket 116 remains. After the introduction of the PTC heating device 2 into the receiving pocket 116, the remaining free space within the receiving pocket 116 can be filled with a typically electrically insulating mass that is thermally well conductive.

(27) FIG. 7 exemplifies an inwardly facing locking projection 32. In the completed product, this locking projection 32 bears in planar manner in the direction toward the PTC element 12, in the present case against the insulating layer 22. The locking projection 32 acts like a barb which prevents the PTC element 12 from being accidentally released from the heater casing 4. After the plastic deformation of the heater casing 4, this locking projection 32 is basically integrated into a flat abutment surface that extends parallel to the insulating layer 22.