EP2025541B1 - Heating element of an electric heating device - Google Patents

Description

The present invention relates to a heat generating element of an electric heating device with the preamble features of claim 1.

Such a heater for air conditioning the interior of a motor vehicle is for example from the EP 1 564 503 known. The heat-generating elements of the heating block usually comprise a plurality of one above the other in a plane provided PTC heating elements, which are arranged between conductor tracks, which are usually formed by metal strips. These tracks are energized with different polarity. The PTC elements can be glued to these tracks. It is also possible to apply the printed conductors under prestress against the PTC heating elements. In any case, it must be ensured that there is good contact between the conductor tracks and the PTC heating elements for decoupling the heat generated by the PTC heating elements and for coupling in current.

One or more heat-generating elements may be provided as part of the heating block. The heat generated by the heat-generating elements is discharged through heat-emitting elements to the medium to be heated, ie the air. This flows through the housing through the two frame openings, which receive the flat heating block between them. The frame openings are usually parallel to each other on opposite sides of a substantially flat, frame-shaped housing. With a view to the most cost-effective production of the electric heater, the heat-emitting elements are usually formed of meandering bent metal strips that form corrugated fins. These corrugated ribs rest on one or both sides of heat-emitting elements. Accordingly, the heating block comprises a plurality of layers of heat-emitting and heat-generating elements, wherein care must also be taken with regard to the heat extraction that the heat-emitting elements abut well on the heat-generating elements. Also for this purpose, the heat-emitting elements can be firmly connected to the heat-generating elements and / or applied by at least one received in the housing spring element under bias. Instead of a meandering sheet-metal strip, the heat-emitting element can also be formed by an extruded aluminum profile which forms webs which extend substantially perpendicular to the layers of the layer structure comprising the heat-emitting and the heat-generating elements. In such a case, the conductor track, ie, the generally planar contact surface for the PTC heating element can be formed by the outer surface of such an extruded aluminum profile. In both alternatives corrugated fin element or extruded profile, the contact surface for the PTC heating elements are designed to be electrically conductive and electrically connected to the housing usually held in isolation from each other held contacts. In the former case, the contacts are usually formed by the exposed ends of the metal strips.

The layered heating block of parallel heat-emitting and heat-generating elements, optionally with the addition of one or more parallel thereto extending spring elements is preferably held in a housing having a U-shaped cross-section. When loading the layer structure with a spring, the frame should be dimensioned so that the spring force can hold permanently even at the elevated temperatures. It should be noted that the insulating frame is nowadays produced not least for economic reasons as an injection molded part. Usual housing today consist of a lower housing part and a housing upper part. The lower housing part forms a receptacle for the individual elements of the heating block and, if necessary, the spring element. In this lower housing part, the individual elements of the heating block are arranged. Thereafter, the heating block is enclosed by joining the upper housing part and the lower housing part in the housing. For this purpose, edges surrounding the frame openings may partially cover the heating block, so that the heating block is enclosed between the frame openings and held in the housing. The two housing parts are then connected to each other, for example via a latching connection.

In this type of assembly, the problem arises that the individual layers of the heating block must be arranged at a predetermined location in the housing. Since not each heat generating element own contacts are assigned, the electrical conditions within the heating block must be taken into account during assembly. However, in order to reduce the production costs, there is also the desire to design the parts of the heating block as standardized as possible, so that identical components can be used for different positions of the heating block.

The present invention relates to a heat-generating element for an electric heater and is based on an electric heater, as shown by the EP 1 061 776 A1 given is. In this prior art, the heat-generating element comprises a positioning frame with receiving openings for receiving at least one PTC heating element. On both sides of the PTC elements are printed conductors, which are latched to the position frame via elastic locking lugs, which overlap the edges of the conductor tracks and fix them relative to the position frame.

The present invention is based on the problem of specifying an improved heat-generating element.

To solve this problem, the present invention provides a heat generating element having the features of claim 1.

The heat generating element according to the invention is characterized in that the holding webs are molded integrally on the position frame by means of injection molding and, after laying the strip conductors on the position frame by forming the interconnects are plastically deformed across.

As a result, a secure structural unit of the position frame, the PTC elements recorded therein and created the PTC elements in the recesses and this thermally contacting tracks.

Accordingly, the holding webs fix the loosely placed and preferably realized in the form of metal strips strip conductors relative to the position frame, whereby a pre-assembled assembly is created, the parts are captively connected to each other. Accordingly, the heat generating element can be easily handled and easily inserted into the housing. Furthermore, the holding webs are applied to the conductor tracks, so that the elements of the heat-emitting element are closely connected to each other and also the PTC heating elements through Concerns are fixed to the inner sides of the conductor tracks in the receptacles, so that, for example, a plurality of PTC heating elements can be arranged and fixed in a receptacle at predetermined locations.

Preferred developments of the heat-generating element according to the invention are specified in claims 2 to 5.

Fig. 1

eine perspektivische Seitenansicht eines Ausführungsbeispiels der elektrischen Heizvorrichtung;

Fig. 2

eine Seitenansicht auf ein Gehäuseunterteil mit darin eingebautem Heizblock des in Fig. 1 gezeigten Ausführungsbeispiels;

Fig. 3

einen vergrößerten Ausschnitt der Darstellung gemäß Fig. 2;

Fig. 4

eine perspektivische Explosionsdarstellung eines wärmeerzeugenden Elementes der elektrischen Heizvorrichtung nach Fig. 1;

Fig. 5

eine Schnittdarstellung entlang der Linie VII-VII gemäß der Darstellung in Fig. 6 eines montierten wärmeerzeugenden Elementes;

Further details and advantages will become apparent from the following description of an embodiment in conjunction with the drawings. In this show:

Fig. 1

a side perspective view of an embodiment of the electric heater;

Fig. 2

a side view of a housing base with built-in heating block of in Fig. 1 shown embodiment;

Fig. 3

an enlarged section of the illustration according to Fig. 2 ;

Fig. 4

an exploded perspective view of a heat generating element of the electric heater according to Fig. 1 ;

Fig. 5

a sectional view taken along the line VII-VII as shown in Figure 6 of a mounted heat-generating element.

The Fig. 1 shows a perspective side view of an embodiment of the electric heater with a housing 2, consisting of a lower housing part 4 and an upper housing part 6. Both housing parts 4, 6 are positively connected to each other and take in a heating block 8, which arranged from a plurality of parallel layers to each other heat-generating elements 10 and heat-emitting elements 12 consists. The heat-emitting elements 12 are formed as corrugated rib elements of meandering bent sheet metal strip.

At one end face of the housing 2, this is surmounted by five contact tongues 15 arranged one above the other in the transverse direction. The contact tongues pass through recesses 16 which are recessed on the housing 2 and which in each case receive a contact tongue and are predominantly formed by the housing lower part 4, but are rounded off at one end by the housing upper part 6.

The housing 2 has two opposite frame openings, of which in Fig. 1 only the frame opening 16 formed by the upper housing part 6 can be seen. The formed by the lower housing part 4 frame opening is in Fig. 4 and identified by reference numeral 18. The frame openings 16, 18 are each interspersed with struts 20 which extend at right angles to the layers of the heating block 8 and connect the opposing longitudinal beams of the lower housing part 4 and upper housing part 8 with each other.

The Fig. 2 shows details of the heating block 8 and its inclusion in particular in the lower housing part 4 and shows the lower housing part 4 in a plan view with the housing upper part removed. The heat-emitting elements 12 are only incompletely shown at the respective front ends of the housing lower part 4. Accordingly, the illustration in Fig. 2 also a view of the frame opening 18 formed by the lower housing part 4 free.

As can be seen, the exemplary embodiment shown has four heat-generating elements 10, which are each accommodated in the housing lower part 4 in an insulating manner and with a certain mobility transverse to the layers of the layer structure (heating block 8). The lower housing part 4 has for this purpose fitting element receptacles 22 which open a receptacle 24, which is formed essentially by the housing lower part 4 and accommodates the heating block 8. At each end face of the lower housing part 4, two different types of fitting element receptacles 22a, 22b are provided in the exemplary embodiment shown (cf. Fig. 3 ). Corresponding to the geometry of the fitting element receptacles 22, the heat-generating elements 10 have at their front ends fitting elements 26a, 26b which respectively fit only in the corresponding corresponding fitting element receptacle 22a or 22b. In the present case, the corresponding fitting element receptacles 22 are matched to the fitting elements 26 provided corresponding thereto, that the heat-generating elements 10 are movable by a few tenths of a millimeter transversely to the longitudinal extent of the layers of the heating block 8 in the housing 2. The outer fitting elements 26a are designed as a hammer head and engage in correspondingly formed fitting element receptacles 22a. These are substantially shorter in the longitudinal direction of the heat-generating element 10 than the second, centrally provided fitting element receptacles 22a. The fitting elements 26b associated with these elongated fitting element receptacles 22b are rod-shaped and less wide than the hammer-head-like fitting elements 26a. Due to this particular configuration, the central heat-generating elements 10 do not fit in the outer positions for heat-generating elements 10 of the heating block. In appropriate Way, the outer heat-generating elements can not be arranged in the middle of the heating block, ie insert into the housing 2.

While the heat-generating elements 10 can not be used anywhere in the housing 2, the heat-emitting corrugated fin elements 12 are nonspecific and as lengths of a meandering curved first sheet metal strip as manufactured and cut from this continuous material to length. Each individual heat-emitting element 12 can be used at any position for a heat-emitting element within the heating block 8.

The fitting elements 26 are integrally formed on a positioning frame 28, which in the 4 and 5 can be seen and explained in more detail below with reference to these figures. The positioning frame 28 is made of an insulating material and serves for the positioning of PTC heating elements 30. In the present case, a receptacle 32 in the positioning frame 28 is recessed for each individual PTC heating element 30, which surrounds this PTC heating element and thus defines it. On both sides of the respective PTC heating elements 30, which are arranged side by side in a plane, are sheet metal strips 34, 36, which form electrical conductors for energizing the PTC heating elements 30 and via which the heat generated by the PTC heating elements to the heat-emitting elements 12 is passed by heat transfer. These lie directly on the metal bands 34, 36 at.

The front ends of the positioning frame 28 are extended over a fitting element web 38 on the position of the metal strips 34, 36 addition. At the outer end of the fitting element webs 38 are the respective fitting elements 26 of the positioning frame 28. As the cross-sectional view along the in Fig. 4 illustrated line VII-VII (cf. Fig. 5 ), the vast extent of the position frame 28 in the width direction of the respective metal bands 34, 36 is taken. In cross-sectional view laterally next to the metal bands 34, 36, the positioning frame on holding webs 40 which are provided immediately adjacent to the lateral edge of the metal strips 34, 36 and the corresponding metal strips 34, 36 project beyond the top and these overlap on the outside, preferably with the tracks 34, 36 in contact and abut this. The holding webs 40 are formed in the embodiment shown in one piece by way of injection molding initially as a right angle to the main extension direction of the position frame 28 outgoing projections. The distance of opposing projections is selected so that the sheet metal strip 34 or 36 just fits between these projections. The one-piece component produced in this way by injection molding is then provided with the essential parts of the heat-generating element 10, ie the PTC heating elements 30 are inserted into the corresponding receptacle 32 and surrounded on both sides by the metal bands 34, 36. Thereafter, the projections are plastically deformed inwardly and so the interconnects 34, 36 formed across. Here, usually a hot forming is used, in which the holding webs 40 forming material locally in the area of the metal strips 34, 36 warms up and thus softened. The means used in each case can locally heat the position frame 28, for example by means of hot air or by heat conduction. In the case of heating by heat conduction, the heating effecting agent is preferably formed by a tool which simultaneously performs the transformation of the retaining webs 40.

The holding webs 40 are not formed continuously in the longitudinal direction of the heat-generating element 10, but are provided in sections 40.1 to 40.5. These sections 40.1 to 40.5 leave between them a passage 41 free, which is designed such that in each case a strut 20 in the width direction between the sections 40.1; 40.2; 40.3; 40.4 or 40.5 fits. In any case, the section formed by the passage 41 projects inwards in relation to the outer surface of the retaining webs 40 so far that at least half the thickness of the struts 20 fits between the retaining webs 40 and is received there.

However, there is a lack of a positive engagement between the struts 20 and the positioning frame 28 in a direction transverse to the layers of the heating block 8, so that a movement is transverse to the layers of the heating block 8 between the struts 20 of the housing parts 4, 6, the may also be referred to as the first strut, and the retaining webs 40, which may be referred to as the second strut 43.

The heat-generating element 10 is formed as a preassembled component and can thus be handled during assembly, without the risk that the conductor tracks 34, 36 or even the inserted in the position frame 28 PTC heating elements 30 are lost. It should be noted, however, that usually the holding webs only fix the metal strips 34, 36 in the position frame, but not with a contact force against the PTC heating elements 30 put, which is sufficient to energize the PTC heating elements 30 during operation safe. This is in any case effected in the embodiment discussed in the context of the present invention by a spring element, which will be explained in more detail below with reference to FIGS. 8 to 10.

First, however, will continue to discuss those features that ensure that parts of the heating block 8 can not be installed at any point within the housing 2.

As in particular the Fig. 3 and 4 can be seen, is a metal strip, namely in Fig. 4 shown sheet metal strip 34, bent out of the plane of the heat generating element 10. Accordingly, an offset 42 results between the plane in which the sheet metal strip 34 abuts against the PTC heating elements 30, and a free end 44, which by repeated, but opposite bending extends parallel to the first-mentioned main portion of the sheet metal strip 34. Again Fig. 3 can be seen, this free end 44 is mechanically and electrically connected by a crimp 46 to the associated contact tongue 14.

In the Fig. 3 labeled with reference numerals 10.3 and 10.4 upper heat-emitting elements have an outgoing from the upper sheet metal strip 34 offset 42.3 and 42.4. The lower heat generating element 10.1 has a downwardly outgoing offset 42.1. The metal strips 34, 36 of the heat generating element 10 marked with reference numeral 10.2 are on both sides to form an offset 42.20 or 42.21 arc and each provided with a contact tongue 14. Due to these differences, it is possible to avoid exchanging the positions for the heat-generating elements 10.3 and 10.2 within the housing 2. In the present case, the embodiment allows that the two middle heat-generating elements 10.2 and 10.3 can be interchanged with one another due to the design of contact tongue receivers 48. A corresponding interchangeability is also given for the two outer heat-generating elements 10.1 and 10.4.

The previously mentioned with reference to Fig. 1 mentioned slits 15 go from the outside of the housing 2 and terminate in the opposite to the slots 15 each widened Kontaktzungenaufnahmen 48. Behind this Kontaktzungenaufnahme 48 turn a narrowed slot 50 is formed, which is a contact tongue 14 formed by punching sheet metal piece and the free end of the 44th can accommodate the associated sheet metal strip 34.

The lower housing part 4 can be molded in an injection mold that can be produced cost-effectively, since all areas significant for the housing 4 extend parallel or at right angles to the frame opening 18 of the housing lower part 4.

Thus, the lower housing part 4 initially substantially mutually perpendicular frame surfaces 52a-d, which surround the heating block 8 circumferentially and perpendicular to the plane containing the frame opening 18 includes. At the end face on which the contact tongues 14 are led out of the lower housing part 4, the corresponding frame surface 52b opens outward via four fitting element web receivers 54 whose main walls likewise extend at right angles to the plane containing the frame opening 18. A corresponding extension have those functional surfaces of the housing lower part 4, which form the contact tongue receptacle 48 and the here leading slots 15 and 50 substantially and those walls which limit the fitting element receptacle 22 and in Fig. 3 are shown. The receptacles 15, 22, 50 and 54 described above are bounded on the side of the lower housing part 4 by a bottom which runs parallel to the plane containing the frame opening 18 of the housing lower part 4.

The particular design of the heat generating elements 10 allows for easier assembly, since the grid assembly formed by the first and second struts 20, 43 is not completely part of the housing, but the second struts are formed with the frame 28 and thus is located where the PTC heating elements 30 come to rest within the heating block 8.

Since the heat-emitting element 12 is prepared as a preassembled unit and further ensured by the fitting elements 26 and the associated receptacles 22 that the heat-generating elements 12 can be installed only at predetermined locations within the housing 2, the manufacture of the electric heater, in particular the assembly of the items also be done by less experienced staff.

The specific embodiment of the embodiment provides an unambiguous assignment of different components of the electric heater. If this clear assignment is not met, the components of the electric heater can not be mounted.

LIST OF REFERENCE NUMBERS

2

casing

4

Housing bottom

6

Housing top

8th

heating block

10

heat generating element

12

heat-emitting element

14

contact tongue

15

slot

16

Frame opening, housing top

18

Frame opening, lower housing part

20

Strut / first strut

22

Pass element receptacle

24

Recording for the heating block

26

pass element

28

position frame

30

PTC heating element

32

Mount for PTC heating element

34

metal strip

36

metal strip

38

Pass bridge element

40

retaining webs

40.1 to 40.5

Sections of the retaining bars

41

passage

42

offset

43

Second strut

44

free end of the sheet metal strip 34

46

Vercrimpungselement

48

Contact tongue receiving

50

slot

52

frame surface

54

Shim web recording

64

longeron

66

longeron

68

pin guide

70

pin guide

72

pin guide

74

window

90

bulge

Claims (5)

1. A heat generating element (10) of an electric heater, comprising:

   a positional frame (28) made of an insulating material, which defines receptacles (32) arranged side by side for receiving at least one PTC heating element (30), which are arranged between conductor paths (34, 36), against which the PTC heating elements (30) are placed in an electrically conductive manner, wherein the positional frame (28) comprises retaining ridges (40) surrounding and limiting the conductor paths (34, 36), which retaining ridges (40) externally overlap the conductor paths (34, 36) and abut on the conductor paths (34, 36),

   characterized in that,
   the retaining ridges (40) are formed integrally with the positional frame (28) by injection molding and are plastically deformed after placing the conductor paths (34, 36) on the positional frame (28) to externally overlap the conductor paths (34, 36) after plastic deformation.
2. The heat generating element according to claim 1, wherein the retaining ridges (40) abut on the conductor paths (34, 36) merely on an edge side thereof.
3. The heat generating element according to claim 1 or 2, wherein the retaining ridges (40) are formed in a plurality of sections with a passage (41) between adjacent sections (40).
4. The heat generating element according to claim 3, wherein the passage (41) extends to the conductor path formed by a continuous sheet metal band (34, 36).
5. The heat generating element according to claim 1, wherein the retaining ridges (40) are bent over the conductor paths (34, 36) by thermoforming.

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