DE202009019076U1 - Electric heater and housing of an electric heater - Google Patents

Abstract

Electric heating device with an open housing, in which at least one sheet metal strips (16) with a PTC element (14) arranged therebetween PTC heating element (12) and at least one thermally conductive adjoining radiator element (10) is held, wherein the housing to the electrical connection of the at least one PTC heating element (12) carries a contact tongue (26) which is connected to a selected sheet-metal strip (16), characterized in that the contact tongue (26) via a crimp connection with the selected sheet-metal strip (16) is connected , which is exposed in a housing opening (68).

Description

The present invention relates to an electric heater and a housing for an electric heater. In particular, the present invention relates to a housing having a housing lower part and a housing upper part. The housing is open, d. H. has at least two regularly opposed openings through which air to be heated flows. In the housing, at least one PTC heating element, which usually comprises two metal strips extending in parallel and PTC elements arranged therebetween, and at least one radiator element adjoining them in heat-conducting fashion are held. Furthermore, contact tongues are supported by the housing, which are provided for the electrical connection of the PTC heating elements and connected to selected metal bands. The contact tongues usually protrude from the outside of the housing designed as a frame and are located within a plug housing, which protrudes laterally from the housing.

Such an electric heater is for example from the EP 1 564 503 B1 known.

In this prior art, the contact tongues are formed by the metal strips themselves. The contact tongues are held in slots formed on the housing which are recessed in a partition which forms a receptacle for the at least one PTC heating element and the radiator element adjacent thereto.

Electric heating devices are also described in the prior art, which also regard the present invention as preferred, and in which the individual layers within the housing, which generate the heat and deliver it to the air to be heated, are held in the housing under spring tension. These layers are formed by the PTC heating element and the adjoining radiator element. Typically, a plurality of such parallel extending layers are held in the manner of a layer structure in the housing under the bias of at least one outside spring.

With regard to a reliable electrical connection of the electric heater via the contact tongues, it is sometimes preferable to form them as separate stampings and to electrically connect with selected metal bands (see. EP 2 019 268 A2 ). Thus, in particular in the automotive industry, have found in the electric heater of the generic type widespread reliable electrical connectors required because with inaccurate contact and the required heating electric heating devices of up to about 2000 W at the given electrical system voltage of 12 V contact resistance to the Contact tongues can lead to thermal problems. Thus, the contact tongues are sometimes formed from pieces of sheet metal, which correspond by punching in a special way the geometry of a mating connector and / or are provided with a coating can be transmitted through the best possible electric current between the contact tongue and a mating connector. The sheet metal strip, however, is usually a semi-finished only cut to length, so that there is a need to reliably connect the contact tongue with the sheet metal strip.

The present invention has for its object to provide an easy to manufacture electric heater, in which the initially separately created contact tongue with a metal strip is connected in a simple manner and reliable. The present invention also seeks to specify a housing for such an electric heater, which is best suited for carrying out a method for producing the electric heater according to the invention.

To solve the device-related problem, the present invention proposes an electric heater of the type mentioned, in which the contact tongue is connected via a crimp connection with the selected sheet-metal strip and the crimp is formed during or after closing the housing.

With regard to a good electrical contact between the contact tongue and the sheet metal strip, it is proposed according to a preferred development of the electric heating device, the contact tongue with at least one integrally formed thereon Quetschlasche, which surrounds the sheet metal strip after making the crimp. Preferably, two squeezing tabs are provided, which preferably protrude from the end of the contact tongue after initial punching and form a receptacle by bending towards each other, [on itself] in which the selected contact plate can be inserted with its free end. After such preparation, only the squeeze bag must be deformed to produce a secure electrical connection, which can be done in a uniaxial motion by a tool which is perpendicular to the extension direction of sheet metal strip and contact tongue against these acted.

To improve the electrical contact, the squeezing tab has at least one deformation notch, by means of which the squeezing tab is plastically deformed into the underlying metal strip. Here, the plastic deformation passes through the entire squeeze and shows up at the Phase boundary between the pinch and the sheet metal strip as from the surface of the squeeze protruding deformation. The deformation notch can be molded with such intensity that a plastic deformation also results in the overlapping area on the sheet metal strip. In any case, the deformation notch leads to a punctual or linear transmission surface between the contact tongue and the sheet-metal strip for electrical current, which ensures reliable electrical contact between the contact tongue and the sheet-metal strip.

The deformation notch is preferably located in the edge region of the sheet-metal strip. Particularly preferably, the sheet metal strip is comprised of two squeezing loops which end approximately at the middle height of the sheet metal strip and which are reliably contacted by deformation notches in the bending or bending region where the squeezing loops are placed over the sheet metal strip. For the same reasons, according to a preferred embodiment, at least one contact projection formed by punching is provided between the sheet metal strip and the squeezing tab. This contact projection is usually formed on the prepared by punching contact tongue. The contact projections are usually opposite to the squeezing tabs and protrude inwards in the direction of the squeezing tabs, in order to effect the most accurate selective electrical contact between the contact tab and the sheet metal strip.

According to a further preferred embodiment of the present invention, squeezing tabs are provided, for example, at the ends of the metal bands opposite the contact tongues, which are electrically connected to a different metal strap short-circuiting contact bridge. This creates the possibility of electrically connecting various PTC heating elements to one another in a simple manner. It is assumed that the electrical contact is made possible to a mating connector at a front end of the housing, preferably by combined in a plug housing contact tongues, whereas the electrical connection between individual PTC heating elements within the housing via said contact bridge. This embodiment is particularly suitable for electrical heating devices in which a PTC heating element with radiator elements resting thereon is accommodated in a compartment of a housing and is kept electrically isolated by another plastic PTC heating element, so that a power transmission between adjacent PTC heating elements is achieved. Heating elements in the transverse direction, d. H. Including the radiator elements is not possible. It is also conceivable to form the contact bridge with a contact tongue and on the connection side, d. H. provided on the side at which the contact tongues are to connect several PTC heating elements on the connection side via a single contact tongue. This development has advantages, in particular in the electrical connection of the electric heater by inserting the contact tongues into a circuit board, which is seated on the housing of the electric heater. The contact bridge, which preferably short-circuits two or more sheet-metal strips to one another and extends it electrically over a single contact tongue to the outside for electrical connection, can reduce the number of contact points on the circuit board. It should be noted that nowadays the housing surrounding the board must be sealed in the region of the openings of the contact tongues regularly at contact tongues for connection to a circuit board. Furthermore, contact springs for the electrical connection of the contact tongues must be formed on the board. By reducing the number of contact blades to be connected to the board, the cost of manufacturing the electric heater can be reduced.

The method for producing the electric heater according to the invention differs from the prior art in that the contact tongue with a selected sheet metal strip are connected during or after closing the housing. In the first alternative, for example, the at least one PTC heating element and the heat-conducting adjoining the radiator element can be inserted into a part of the housing, for example the housing lower part. Likewise, a possibly the layer structure under bias holding spring can be inserted into the housing.

This is preferably done according to the from EP 1 564 503 B1 known procedure, in which initially the layer structure and the spring element are used stress-free in the housing base. The closing of the housing is preferably carried out by introducing a displacer in the housing, through which the receiving space is reduced within the housing such that the spring and thus the recorded layer structure in the housing is placed under spring tension. Therefore, a considerable force is required for the closing of the housing, since in this case not only closed the housing, but also the spring is placed under pretension.

The closing of the housing takes place in particular with a pressing tool, which has bearing surfaces for surface contact with the outside of the housing base and housing upper part. From these contact surfaces contoured pressing jaws protrude, cause the tool-assisted closing of the housing in the overlapping region between the contact tongue and the sheet metal strip a plastic deformation by which both elements are electrically connected together.

Thereafter, it is possible to close with a tool-assisted joining movement both the housing, and preferably to produce all electrical connections between selected metal bands and the contact tongues.

In an alternative process management, the housing is first closed, including PTC heating element and radiator element optionally one or more spring elements and the contact tongues. The latter have an overlap area with the metal bands. This overlap region is located in the region of the ends of selected metal strips, which are usually extended laterally beyond the length of the PTC heating element and / or the radiator element. As far as below is based on several crimp connections for contacting a plurality of metal strips with associated reeds, it should not be expressed hereby that the invention can not be implemented with only one sheet metal strip and a contact tongue. Nevertheless, there are particular advantages in terms of cost-effectiveness, if the joining by making a crimped connection covers all electrical connections between the intended reeds and sheet metal strips.

In the second alternative, the housing preferably has receptacles for the predetermined retention of the contact tongues on the housing. When loading the housing, the metal strips are preferably inserted into squeeze tabs, which are preferably formed on the contact tongue, since these can be formed as a more complicated stamped part, whereas it is preferable in terms of economic production, the sheet metal strip only by cutting if necessary bending a sheet-metal To prepare semifinished product. By introducing the free end of the sheet metal strip in the squeeze, the overlap region is created between the two elements. The thus prepared components are inserted into the housing. The housing is closed. After closing the housing, the reeds with the metal bands are electrically connected to the required safety for power transmission, d. H. by plastic deformation a crimp connection of the previously positioned in the housing sheet metal strips is effected with the contact tongues.

In the process management usually no special facilities are necessary to keep the sheet metal strip and the contact tongue for making a connection. Rather, the positioning of the metal bands and the contact tongues by insertion into the housing part. When closing or after closing the tool, the reliable electrical connection between the contact tongue and the associated sheet metal strip is then produced.

Preferably, the contact tongue with the selected sheet metal strip is connected by plastic deformation of a crimp, which takes place by pressing jaws. The pressing jaws are preferably motor-driven and designed in such a way that all the contact tongues of the electric heating device are plastically deformed with the associated metal bands as a result of the feed movement of the pressing jaws and thus are securely connected electrically. These press jaws according to a preferred development contact surfaces for joining the housing and are thus part of a joining tool, which is both suitable to close the housing and to make the electrical connection between the contact tongues and the metal bands. At this joining tool, the abutment surfaces can be designed to be movable relative to the pressing jaws in order to bring the advancing movement of the abutment surfaces to a halt after closing the housing, while at the same time the pressing jaws are moved towards each other for plastic deformation of the crimping connection.

The housing proposed by the present invention for an electric heater forms in a conventional manner a receptacle for the at least one PTC heating element and the at least one adjoining radiator element and has a lower housing part and an upper housing part (see. EP 1 564 503 B1 ). It may further comprise a receptacle for at least one spring element, by which the radiator element is applied under bias against the PTC heating element. The housing is open, ie provided with at least two opposing openings for the passage of air to be heated. This air passage opening can be interspersed, for example, with transverse and longitudinal struts. The longitudinal struts may in particular extend parallel to the PTC heating elements and cover and / or encapsulate them, so that only the radiator elements are exposed between the air passage openings. The housing further has an insertion opening for a forming tool, through which selected metal strips in the region of their ends by forming with associated contact tongues are connectable. The insertion opening preferably extends transversely to the longitudinal extent of the metal bands and / or the radiator elements and leaves a plurality of metal bands in the region of their ends free. The Insertion opening leaves at least the overlap area between the contact tongue and sheet metal strip free and is matched in terms of their dimension to the dimension of the forming tool such that it can be introduced into the housing for forming all the contact tongues. The introduction opening may be separated by webs, which stiffen the housing in the region of the introduction opening and / or increase the air resistance in the region of the introduction opening, in order to avoid a bypass flow through the introduction opening, which can lead to an insufficient heating of the air flow, if this instead of passing by the radiator elements, wholly or predominantly flows through the introduction opening. Likewise, a cover may be part of the housing, which is placed after the forming processing on the insertion opening to close this completely or partially.

According to a preferred embodiment of the present invention, the lower housing part and the upper housing part respectively form covers of the housing. These covers extend parallel to each other with the housing closed and save the air passage opening and the insertion opening. The introduction opening and the air passage opening in the cover of the lower housing part or of the upper housing part are therefore provided parallel to one another. Usually, both openings extend in the same plane, which is predetermined by the cover. The introduction opening is preferably provided in the manner of a longitudinal slot with an extension which runs parallel to a transverse spar formed by the lower housing part and the upper housing part. From this cross member protrudes a plug flange, which surrounds the usually perpendicular to the cross member extending contact tongues to form guide and retaining surfaces for the housing of a mating connector.

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

1 a plan view of a equipped with PTC Heizlementen and radiator elements housing lower part;

2 a metal band with associated contact tongue before joining;

3 the sheet metal strip and the contact tongue according to 2 after joining;

4 a contact bridge to the in 1 embodiment shown;

5 an end portion of another embodiment of an electric heater and

6 a sectional view taken along the line VI-VI according to 5 with a pressing tool.

1 shows a plan view of a reference numeral 2 characterized housing lower part, which a plurality, by on the housing lower part 2 trained partitions 4 separate compartments 6 for holding heating rods 8th formed. Every heating element 8th includes two radiator elements 10 that between them is a PTC heating element 12 lock in. The PTC heating element 12 comprises longitudinally arranged in a plane side by side PTC elements 14 between tinplate bands 16 are arranged.

Selected metal strips 16 are laterally, ie over the length of the radiator elements 10 extended and beyond the Gefach 6 , On the left side of the housing base 2 , which forms the connection side, there is a Einbringgefach 18 which passes through an intermediate wall 20 from the compartments 6 and a crossbar 22 is limited to the outside. The crossbar 22 is with recording slots 24 each provided by a contact tongue 26 are penetrated.

On the opposite transverse side is between the other outer cross member 28 and another partition and between partitions 30 another Gefach 32 formed, in which two selected metal strips 16.2 and 16.3 protrude. These metal bands 16.2 and 16.3 are via a contact bridge 34 electrically connected to each other.

In the embodiment shown, the heating elements 8th electrically isolated from each other in the compartments 6 held. Between the individual subjects 6 for the heating elements 8th there are free spaces 36 passing through a cover 38 of the housing base 2 outside are blinded. The cover 38 forms in the field of divisions 6 the bottom of the housing base 2 out. In the field of open spaces 36 can the cover 38 be offset inside. The cover 38 points in the field of open spaces 36 Air passage openings 40 on.

The 2 to 4 show elements for the energization of the electric heater according to 1 , For the electrical connection from the outside are the contact tongues 26 formed of a highly electrically conductive material and provided with a silver coating. The tongues 26 have a holding slot 42 one in the area of the receiving slot 24 remaining web of the transverse spar 22 spills over to the contact tongue 26 in the longitudinal direction of the housing lower part 2 to secure. The inner end of the contact tongue 26 is by punching with squeeze pockets 44 provided, which are first bent to each other by punch-bending processing to a recording 46 for the tongue of contact 26 associated sheet metal strip 16 train. An end area 48 of the sheet metal strip 16 has a bending offset 50 on, through which the free end 52 of the sheet metal strip 16 opposite to a contact surface 54 is aligned for the PTC elements forming plane offset.

On the squeeze pockets 44 opposite inside are at the contact tongue 26 Contact projections 56 formed by punching, that of the otherwise flat side surface of the contact tongue 26 towards the squeeze patches 44 protrude.

For connecting sheet metal strip 16 and contact tongue 26 First, the free end 52 the contact tongue 26 in the recording 46 introduced until the free end 52 the squeeze pockets 44 surmounted (cf. 3 -). In this state, first, the sheet metal strip 16 and the contact tongue 26 in the lower housing part 2 brought in.

4 clarifies the details of in 1 shown contact bridge 34 that has a middle connecting leg 58 and approximately at right angles to projecting contact legs 60 each having a squeeze tab 62 are provided. The squeezefuls 62 form between itself and the associated contact leg 60 a U-shaped recording 64 out. The contact bridge 34 is after inserting the metal strips 16.2 and 16.3 put on this, so that in the Gefach 32 protruding free ends of these metal bands 16.2 and 16.3 in the U-shaped recording 64 are included and a curvature area 66 the squeeze pockets 62 on the narrow end of the metal bands 16 rests.

The thus prepared housing base is covered in the course of production of the electric heater with an upper housing part, which in any case one, the radiator elements 10 having free opening. The upper housing part may be formed, for example, as a housing cover, which only the PTC heating elements 12 and a part of the spaces between the partitions 20 and the crossbars 22 respectively. 28 covers. In this case, the lower housing part and the upper housing part each leaves an insertion opening free, the frontal boundary in 1 indicated by dotted lines and with reference numerals 68 for the connection side and 70 marked for the opposite transverse side.

As a result, the connection points between the contact bridge 34 and the associated metal bands 16.2 and 16.3 on the one hand and the selected metal bands 16.1 . 16.3 and 16.4 and the associated contact tongues 26 free on the opposite side surfaces of the housing.

After or during the closing of the housing can take place at these locations a forming, through which the reeds 26 respectively. 62 in a predetermined manner electrically with the metal bands 16 be contacted. At the end of this forming process are the squeeze pockets 44 the tongues of contact 26 approximately parallel to its side surface, which also has the contact surface 54 of the sheet metal strip 16 forms. Due to the forming process are at the edge region of the sheet metal strip 16 deformation notches 72 formed the squeezing pockets 54 in the area of curvature 66 enforce and selective contact points between the contact tongue 26 and the tin band 16 form. These contact points usually also cause a plastic deformation of the material of the metal strips 16 , Due to the plastic deformation of the squeezing tabs 66 are otherwise the contact projections 56 with pressure against the sheet metal strip 16 created. The crimping leads to an intimate connection between the two parts 16 . 26 and a reliable contact at the phase boundary.

The same results for the forming processing of squeezing 62 the contact bridge 34 , The deformations of both the contact bridge 34 as well as the reeds 26 is preferably carried out simultaneously by simultaneous introduction of pressing jaws on both sides of each other in the insertion openings 68 respectively. 70 be introduced.

The 5 and 6 illustrate a second embodiment, wherein 5 the connection-side end of a reference numeral 74 marked housing illustrates which one by cross struts 76 and longitudinal struts 78 interspersed passages 80 for forming air to be heated. In this passage 80 are only the radiator elements 10 free. The assigned PTC heating elements are behind the individual longitudinal struts 78 and are covered by these.

The metal strips of selected PTC heating elements are laterally over the radiator elements 10 extended and each provided with a bending offset, so that their free ends with approximately uniform spacing in the transverse direction relative to each other between the opposing insertion openings 68 of the housing 74 exposed. The bending offset is indicated here by dash-dotted lines and is located behind a Glendsteg 82 , which is formed by the housing lower part or housing upper part and transversely to the crossbar 28 extends. The crossbar 28 is through a mounting flange 84 surmounted by a connector housing 86 protrudes, which all reeds 26 surrounds the heater and forms guide or mounting surfaces for a mating housing of a mating connector.

In the 6 Sectional view illustrates the deformation processing after closing the housing for establishing a secure electrical connection between the contact tongues 26 and the associated metal bands 16 , This in 6 with reference number 100 characterized pressing tool has an upper part 102 and a lower part 104 , Of each mutually associated pressing jaws 106 . 108 protrude, the wedge-shaped tapering, in the longitudinal direction of the metal strips 16 extending press recordings 110 form, from their inclined surfaces 112 two in the longitudinal direction of the metal strips 16 with spaced apart provided Quetschkeile 114 protrude.

When introducing the pressing jaws 106 . 108 in the introduction openings 68 be first by the wedge-shaped configuration of the press recordings 110 the metal bands 16 and the associated contact tongues 26 embraced on top and bottom. As the movement of upper and lower part progresses 102 . 104 Finally, the squeezing wedges act on one another 114 against the curvature areas 66 so that these finally have the deformation notches 72 form.

With this forming process all contact tongues 26 at the same time and in one with the associated metal bands 16 connected. The housing 74 serves to position the parts to be joined.

LIST OF REFERENCE NUMBERS

2

Housing bottom

4

partition wall

6

partitions

8th

heater

10

radiator element

12

PTC heating element

14

PTC element

16

metal strip

18

Einbringgefach

20

partition

22

transverse spar

24

receiving slot

26

contact tongue

28

transverse spar

30

partition wall

32

Gefach

34

Contact bridge

36

free space

38

cover

40

Air passage opening

42

retaining slot

44

squeeze

46

admission

48

end

50

bending offset

52

free end

54

contact surface

56

contact projection

58

connecting leg

60

contact legs

62

squeeze

64

U-shaped receptacle

66

curvature region

68

introduction opening

70

introduction opening

72

deformation notch

74

casing

76

crossmember

78

longitudinal strut

80

Through opening

82

blend Steg

84

mounting flange

86

plug housing

100

press tool

102

top

104

lower part

106

pressing jaw

108

pressing jaw

110

Press recording

112

sloping surface

114

Quetschkeil

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1564503 B1 [0002, 0013, 0020]
• EP 2019268 A2 [0005]

Claims (9)

Electric heating device with an open housing in which at least one metal strip ( 16 ) with an interposed PTC element ( 14 ) comprehensive PTC heating element ( 12 ) and at least one heat-conducting radiator element ( 10 ), wherein the housing for the electrical connection of the at least one PTC heating element ( 12 ) a contact tongue ( 26 ) with a selected sheet metal strip ( 16 ), characterized in that the contact tongue ( 26 ) via a crimp connection with the selected sheet metal strip ( 16 ) connected in a housing opening ( 68 ) is exposed. Electric heating device according to claim 1, characterized in that the contact tongue ( 26 ) At least one integrally formed thereon Quetschlasche ( 44 ; 62 ), which after producing the crimped connection the sheet metal strip ( 16 ) surrounds. Electric heating device according to claim 1 or 2, characterized in that the squeezing tab ( 44 ; 62 ) at least one deformation notch ( 72 ), through which the squeeze bag ( 44 ; 62 ) into the underlying metal strip ( 16 ) is plastically deformed. Electric heating device according to claim 4, characterized in that by the deformation notch ( 72 ) the sheet metal strip ( 16 ) in an edge region thereof. Electric heating device according to one of claims 1 to 4, characterized in that squeezing tabs ( 44 ; 62 ) on spaced sheet metal strips ( 16 ) are provided, which are electrically connected to a different metal strips ( 16 ) short-circuiting contact bridge ( 34 ) are connected. Electric heating device according to claim 5, characterized in that one of the squeezing tabs connected to the contact bridge ( 44 ; 62 ) is surmounted by a contact tongue. Electric heating device according to one of the preceding claims, characterized in that between the sheet metal strip ( 16 ) and the squeeze bag ( 44 ; 62 ) at least one formed by punching contact projection ( 56 ) is trained. Housing for an electrical heating device for receiving at least one metal strip ( 16 ) and an interposed PTC element ( 14 ) PTC heating element ( 12 ) and at least one thermally conductive adjoining radiator element ( 10 ) the housing having an opening for the passage of air to be heated through the housing exposed, characterized by a plurality of metal strips ( 16 ) in the region of their ends release opening ( 68 ; 70 ) for a forming tool, with the selected metal strips ( 16 ) in the region of their ends by forming with associated contact tongues ( 26 ) are connectable. Housing according to claim 8, characterized in that a housing lower part ( 82 ) and an upper housing part each form covers which extend parallel to each other and in which the at least one opening for the passage of air to be heated and the introduction openings ( 70 ; 72 ) are recessed, wherein the introduction openings ( 70 ; 72 ) substantially parallel to a through the upper housing part and the lower housing part ( 2 ) formed transverse bar ( 22 ; 28 ), from which a plug housing ( 86 ) for holding an electrical connector protrudes.

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