EP2236330B1 - Electric heater for a motor vehicle - Google Patents

Description

The present invention relates to an electrical heating device for a motor vehicle with at least one PTC heating element with essentially parallel aligned and between at least one PTC element receiving contact plates and a printed circuit board, which forms at least one recess formed by a contact plate formed by a contact tongue for the electrical connection of the PTC element to the printed circuit board is penetrated.

Such electrical heaters, which are also referred to as PTC heaters, are used for heating in the motor vehicle. For example, with the EP 1 157 867 a known as generic forming electric heating device, in which a plurality of two parallel aligned contact plates and therebetween in a plane successively arranged PTC elements formed heat-generating elements are accommodated in a frame. These heat-generating elements are provided alternately to heat-emitting elements. The layer structure thus formed is held clamped in a frame.

Selected contact plates of the individual heat-generating elements are laterally extended beyond the heating block to provide contact tongues for the electrical connection of the heating block. In the EP 1 157 867 These contact tongues are passed through recesses of a printed circuit board, which is equipped with components. On the side facing away from the heating block, the printed circuit board carries a spring element projecting over the printed circuit board, which clamps the contact tongue and makes electrical contact with the printed circuit board.

A similar structure with respect to the contact between the contact tongue and the circuit board is from the EP 1 872 986 known. In this prior art, two contact plates each take several stacked PTC elements between them. The heat-generating element thus formed is braced via an externally acting wedge element, which is supported on a pocket and pushed into this pocket, so that the individual layers abut each other with good contact. The wedge element accordingly causes the function of a spring, which in the EP 1 157 867 A1 clamped the layer structure within the frame. Also at the EP 1 872 986 Be the contact tongues formed by the contact plates by recesses of the circuit board passed through to be clamped in spring elements which project beyond the printed circuit board on the heat-generating elements facing away from the back.

The present invention is based on the problem of specifying a compact electrical heater.

To solve this problem, the present invention provides an electric heater having the feature of claim 1. This differs from the generic state of the art in that a stamped connection piece is provided, which is connected in an electrically conductive manner to a conductor track of the printed circuit board. The connecting piece has a voltage applied to the circuit board attachment portion and at least one projecting into the recess spring tongue.

A printed circuit board in the sense of claim 1 can be any printed circuit board, regardless of whether it is now equipped with components, or merely comprises conductor tracks for conducting current between two points. Such a conductor track can be provided, for example, to provide electrical connections to the electric heater at a location remote from the contact plates. Regularly, the contact sheets are extended in a straight line over the heating block and through the recess of the printed circuit board. Although punching processing can provide contact plates also in any direction at an angle to the longitudinal extension of the contact plates of the heating block aligned plug contact. For manufacturing reasons, however, such embodiments are considered limited in terms of their spatial extent. It is also of interest that the space for housing the electric heater in the motor vehicle is regularly limited.

This is where the present invention starts and proposes, for the electrical connection of the contact plate projecting through the printed circuit board, at least one spring tongue projecting into the recess. This spring tongue is part of a connecting piece, which in addition to the said spring tongue has at least one on the printed circuit board generally full-surface fitting portion. This attachment portion serves to one of the attachment of the connector to the circuit board. On the other hand, an electrical connection between the spring tongue and thus the contact plate and at least one conductor track of the printed circuit board is produced via the attachment portion regularly.

In contrast to the generic state of the art, in which the spring element for holding and electrical contact with the circuit board dominates the same considerably, resulting in a considerable extension of the circuit board and the components mounted thereon in the longitudinal direction of the contact plates, the contact plate is clamping spring tongue in the recess which is recessed by the circuit board for passing the contact tongue.

In a preferred development, which does not lead to a substantial increase in the dimension of the printed circuit board in the direction of extension of the contact sheets, the spring tongue is located substantially in the plane formed by the printed circuit board. Preferably, the spring tongue is provided in this preferred embodiment completely within the plane of the circuit board, i. the spring tongue projects beyond the printed circuit board with its free end, which is usually provided on the side of the printed circuit board facing away from the fastening section.

The spring tongue preferably extends directly from the fastening section at the level of the recess and extends from the fastening section exclusively in the direction of the recess. The trained in such a way spring tongue does not or only very insignificantly on the thickness of the circuit board. The electrical connection of the contact plate can therefore be extremely space-saving.

With a view to solid contact as possible between the spring tongue and the contact tongue is proposed according to a further preferred embodiment of the present invention to support the spring tongue with its free end to a surrounding wall of the recess of the circuit board. This wall usually extends at right angles to the top and bottom of the circuit board. The spring tongue supported in this way can exert a relatively high contact force against the contact tongue, which improves the contacting of the contact tongue on the spring tongue.

With regard to a defined contact surface between the spring tongue and the contact tongue, it is proposed according to a further preferred embodiment of the present invention that the surface of the spring tongue cooperating with the contact tongue after insertion of the contact tongue into the recess is convex. This convex configuration can preferably be done by reshaping the surface of the contact tongue. The convex configuration leads to a point or linear system between the spring tongue and the contact tongue formed usually from a flat sheet metal strip. Accordingly, the spring force caused by the spring tongue is transmitted via a small but defined contact surface on the contact tongue, resulting in a secure and reliable contact.

According to a further preferred embodiment of the present invention, respective spring tongues are formed on opposite sides of the recess. These spring tongues all protrude into the recess and are preferably connected to a common attachment portion which rests on the surface of the conductor track. The spring tongues are preferably offset from one another and provided by cutting and bending out of the sheet metal plane of the semifinished product in an alternating manner, so that the respective spring tongues are opposite walls of the recess and clamp between them the contact tongue.

In a preferred development of the attachment portion is located on the at least one PTC element facing side of the circuit board, so that upon insertion of the contact tongue under application of an elastic bias of the spring tongue, the friction force arising in this case over the contact surface between the mounting portion and the surface of the circuit board is held. In particular, it is not to be feared that the connecting piece, in particular the fastening portion, will be lifted off the printed circuit board when the contact tongue is introduced into the recess.

According to a further preferred embodiment of the present invention, the connecting piece has at least one holding web, which is produced by stamping and bending of the sheet metal strip forming the connecting piece. This retaining bar protrudes from the mounting portion, regularly at approximately right angles thereto and is engaged in a recessed on the circuit board mounting hole. By this holding web, a positionally accurate positioning of the connection piece during assembly is made possible on the one hand. The fitting is not mounted in place relative to the printed circuit board until the at least one retaining ridge is engaged in the associated mounting hole.

According to a preferred embodiment, the mounting hole is further filled with solder and the holding web is electrically connected to a conductor track of the printed circuit board. The solder regularly contacts the peripheral surface of the mounting hole, which in turn is lined with an electrically conductive coating. So the mounting hole should preferably be provided on the inside with a copper coating, via which a good electrical connection between the holding web, the solder received in the mounting hole and a conductor formed on the top and / or bottom of the circuit board and electrically connected to the peripheral coating of the mounting hole given is.

The holding web preferably has a width which corresponds approximately to the diameter of the mounting hole. This results in a positionally accurate positioning of the connector after insertion of the retaining web in the mounting hole.

According to the embodiment according to claim 10 of this positionally accurate introduction of the retaining web is promoted in the mounting hole. After this development, an intermediate web is provided between the holding web and the attachment portion which rests on the printed circuit board, which is formed curved relative to the printed circuit board. The holding web and the intermediate web are preferably cut out by punching the sheet forming the fastening portion to a strip. The gutter is bent by bending the strip curved relative to that contact surface of the printed circuit board, which is provided for the attachment portion. The protruding from the underside of the attachment portion portion of the strip accordingly extends preferably strictly perpendicular to this underside, whereby the positionally accurate insertion and positioning while maintaining a flat abutment of the attachment portion is ensured at the top of the circuit board.

Preferably, the attachment portion is particularly preferably flat over the whole area on a conductor tracks formed on the surface of the printed circuit board.

Figur 1:

eine perspektivische Ansicht eines Ausführungsbeispiels des Anschlussstü- ckes;

Figur 2:

das in Figur 1 gezeigt Ausführungsbeispiel in einer perspektivischen Drauf- sicht nach Montage an der Leiterplatte;

Figur 3:

eine Schnittansicht entlang der Linie III-III gemäß der Darstellung in Figur 2;

Figur 4:

eine Schnittansicht entlang der Linie IV-IV gemäß der Darstellung in Figur 2; und

Figur 5:

eine Schnittansicht entlang der Linie V-V gemäß der Darstellung in Figur 2 mit einer die Leiterplatte durchragenden Kontaktzunge.

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:

FIG. 1:

a perspective view of an embodiment of the Anschlussstü- ckes;

FIG. 2:

this in FIG. 1 shown embodiment in a perspective perspective view after mounting on the circuit board;

FIG. 3:

a sectional view taken along the line III-III as shown in FIG FIG. 2 ;

FIG. 4:

a sectional view taken along the line IV-IV as shown in FIG FIG. 2 ; and

FIG. 5:

a sectional view taken along line VV as shown in FIG FIG. 2 with a contact plate projecting through the printed circuit board.

The FIGS. 1 and 2 show perspective views of an embodiment of a connector for itself ( FIG. 1 ) and after installation in a printed circuit board, which is identified by reference numeral 1 and on the upper side, a conductor 2 made of copper is provided. On the conductor track 2 is a connection piece 3, whose essential components are described below with reference to the FIGS. 1 and 2 be explained.

In the middle of this mounting portion 4 are located on opposite sides of an elongated recess 5 alternately provided spring tongues 6. The spring tongues 6 are formed by punching and bending from the connecting piece 3 forming sheet metal strip. The spring tongues 6 are all to the in FIG. 1 shown lower or contact side of the connecting piece 3 is bent. Each spring tongue 6 has a convexly convex contact surface 7 with respect to the convex region of the curvature of the spring tongues 6. This contact surface 7 projects beyond the provided in the longitudinal direction of the spring tongue 6 curved outer surface of the spring tongue 6. At opposite ends and diagonally to each other 3 holding webs 8 are provided. These holding webs are made by punching and bending. In this case, first of the connecting piece 3 forming sheet metal strips in the longitudinal direction of the metal strip extending strip is cut, which is deformed between the mounting portion 4 and the holding web 8 by bending to a mounting portion 4 on the outside bent over gutter 9, the holding web 8 with the Attachment section connects.

As is apparent from the above description, the terminal 3 is formed solely by punching on a metal strip. In this case, the attachment portion 4 forms a contact surface on the circuit board 1 and thus a flat, positionally accurate positioning and contacting to the circuit board. The holding webs 8 are used for positioning and attachment and the electrical contacting of the connector 3 in the circuit board in a manner to be described.

The spring tongues 6 in the preferred embodiment of the connection piece and therefore also all the elements thereof are preferably formed from copper beryllium (BeCu25). For cost reasons, preferably only the contact surfaces 7 of the spring are provided with a coating of silver approximately 2.5 .mu.m thick.

The FIG. 2 shows the connector 3 after arranging on the circuit board. The spring tongues 6 are located in a recess 10 (see. FIG. 5 ), which is recessed on the circuit board and which is penetrated for receiving a contact tongue, which is formed by a contact plate, not shown, of this.

In FIG. 2 are further provided by rings 11 clarified areas or surfaces for the SMD handling. About these surfaces, the connector 3 is held during assembly and positioned on the circuit board.

As the FIGS. 2 to 4 can recognize, the conductor 2 forms the contact surface for the connector 3. In this case, the attachment portion 4 is located over its entire surface against the conductor 2 with its underside. The holding web 8 extends through a mounting hole 12, which is recessed in the printed circuit board 1 and coated circumferentially with the material of the conductor tracks (copper). In this mounting hole 12 of the retaining web 8 is inserted and fixed by means of solder. This results in a solid electrical contact with the conductor 2 and otherwise an attachment of the connector 3 to the circuit board 1. As in particular FIG. 4 can be seen corresponds to the width of the retaining web 8 approximately the diameter of the mounting hole 12 so that when inserting the retaining web 8 in the mounting hole 12, the connector 3 is fixed very accurately with respect to the circuit board 1.

The FIG. 5 shows a sectional view taken along line VV as shown in FIG FIG. 2 and thus a cross-sectional view through the elongated recess 5 of the printed circuit board 1. It is to be imagined that the heat-generating PTC elements and their respective contact plates with respect to the representation in FIG. 4 are arranged below the circuit board 1. As part of this heat generating element is in FIG. 5 only the end of a contact plate 13, which forms a contact tongue 14, shown. This contact tongue 14 is passed through the recess 10 of the circuit board 1, ie passes through the printed circuit board 1. The passage of the contact tongue 14 takes place between the mutually opposite spring tongues 6, which in this case are displaced in the direction of the recess 10 limiting walls 15. This displacement takes place by elastic bending of the spring tongues 6 at the point where they depart from the attachment portion 4. When inserting the contact tongue 14 between the spring tongues 6, these are finally applied with their free end against the inner wall 15 of the recess 5, resulting in an increased spring force, which is the contact tongue 14 securely contacted and pressed between the spring tongues 6. Since the introduction of the contact tongue 14 takes place from the side through the printed circuit board 1, against which the mounting portion 4 of the connector 3, this is pressed against the underside of the circuit board 1, when the spring tongues 6 of the insertion movement of the contact tongue 14 opposes a certain resistance. By this system on the underside of the circuit board 1, the connector 3 is always safely stored.

As FIG. 5 can be seen, the spring tongues 6 are located in total within the recess 10, ie between the top and bottom of the circuit board 1. It is a very compact design created over the contact tab 14 is electrically connected to a conductor 2 of the circuit board 1 in a simple manner can be. The spring tongues 6 are formed such that, for example, a contact tongue with the embodiment according to the in FIG. 4 shown contact tongue 14 can also be inserted from the opposite side into the recess 10 and contacted with the circuit board 1. It is preferable to mount all the connectors 3 from the same side on the circuit board 1. This side of the printed circuit board 1, referred to below as the component side, can also be the one which exclusively carries the components mounted on the printed circuit board 1. In such an embodiment, the finished assembly of the circuit board 1 on one side, that is done exclusively by the component side.

LIST OF REFERENCE NUMBERS

1

circuit board

2

conductor path

3

connector

4

attachment section

5

Recess, connection piece

6

spring tongue

7

contact area

8th

holding web

9

gutter

10

Recess, circuit board

11

Surface for SMD treatment

12

mounting hole

13

contact sheet

14

contact tongue

15

inner wall

Claims (11)

1. An electric heating device for a motor vehicle, comprising at least one PTC heating element with contact metal sheets (13) extending substantially parallel to one another and accommodating between them at least one PTC element, and a printed circuit board (1) having formed therein at least one opening (10) through which a contact tongue (14) projects, which is defined by a contact metal sheet (14) and which serves to establish an electric connection between the PTC heating element and the printed circuit board (1),
   characterized by
   a punched-out connection piece (3) connected to a conductor path (2) of the printed circuit board (1) in an electrically conductive manner, said connection piece (3) defining a fixing portion (4), which rests on the printed circuit board (1), and at least one spring tongue (6) projecting into the opening (10).
2. The electric heating device according to claim 1, characterized in that the spring tongue (6) is located substantially within the printed circuit board (1).
3. The electric heating device according to claim 1 or 2, characterized in that the free end of the spring tongue (6) rests on a wall (15) surrounding the opening (10).
4. The electric heating device according to any of the preceding claims, characterized in that a surface (7) of the spring tongue (6) cooperating with the contact tongue (14) is convex in shape.
5. The electric heating device according to claim 4, characterized in that a plurality of spring tongues (6) project into the opening (10) from opposite sides.
6. The electric heating device according to claim 4 or 5, characterized in that the spring tongues (6) are arranged on opposite sides of the opening (10) such that they are displaced relative to one another.
7. The electric heating device according to any of the preceding claims, characterized in that the fixing portion (4) is arranged on the printed circuit board side facing the at least one PTC element.
8. The electric heating device according to any of the preceding claims, characterized in that at least one holding lug (8) projects from the fixing portion (4), said holding lug (8) being produced by punching and bending and engaging a fastening hole (12) formed in the printed circuit board (1).
9. The electric heating device according to claim 8, characterized in that the fastening hole (12) is filled with a solder, and that the holding lug (8) is electrically connected to a conductor path (2) of the printed circuit board (1).
10. The electric heating device according to claim 8 or 9, characterized in that the holding lug (8) and an intermediate piece (9) located between said holding lug (8) and the fixing portion (4) are cut out, by punching, in the form of a strip from the metal sheet defining the fixing portion (4), and that the intermediate piece (9) is formed into a curved protruding shape by bending the strip relative to a contact surface for the fixing portion (4), said contact surface being defined by the printed circuit board (1).
11. The electric heating device according to any of the preceding claims, characterized in that the fixing portion (4) rests on a conductor path (2), which is formed on the surface of the printed circuit board (1), in planar contact therewith.

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