DE102012109768A1 - Radiator element for electric heater, for heating air current in combustion engine of motor vehicle, has fin element comprising curved corrugated fins that are electrically connected to contact element by screw made of hard material - Google Patents

Abstract

The element has a heat exchange surface-providing corrugated fin element (8) comprising meandering curved corrugated fins (10) that are electrically connected to a contact element by a screw i.e. self-tapping screw, made of hard material. The screw and the contact element are firmly bonded. The contact element and the screw are fixed with a common surface layer. The corrugated fins are connected with each other by crimping tabs (16). The screw passes through an end face of each of the corrugated fins. Independent claims are also included for the following: (1) a heating stage (2) a method for manufacturing a radiator element.

Description

The invention relates to a radiator element for an air heater according to the preamble of claim 1, a running with such a radiator element heating stage and a method for producing such a radiator element.

For use in motor vehicles, especially with consumption-optimized internal combustion engines electrical heaters are often used for heating air streams. Such heaters can be used for high-voltage and low-voltage applications in the automotive industry, but also in industrial technology, for example in control cabinet heaters, auxiliary heaters for low-energy houses, etc.

The basic structure of such heaters is for example in the EP 0 350 528 B1 the applicant discloses. Accordingly, the heating device has a plurality of heating stages, which are controllable depending on the heating power to be retrieved and in principle consist of two radiator elements between which heating elements, preferably PTC heating elements (positive temperature coefficient) are arranged. In the prior art, these radiator elements are designed as corrugated ribs, which are bent meander-shaped from a sheet metal strip, wherein the individual corrugated ribs in the adjacent regions to their vertices mutually abut each other.

Especially in applications that provide protection against contact or low-voltage applications, these corrugated fins are electrically contacted and thus have a dual function: First, the enlargement of the heat exchange surface through which the heat generated by the PTC resistor elements to the medium flowing through the heater, in particular air becomes; On the other hand, the corrugated rib elements also serve as electrical connection elements, via which the PTC resistor elements are supplied with current.

At the time of the EP 0 350 528 B1 known solution, the electrical contacting of the corrugated fin elements via metal strips, which are made for example of aluminum, brass or copper. These sheet metal strips (cover plates) abut against the crests of the corrugated fins, wherein the electrical contacting to the outside, for example in a housing with electronics, via contact elements. In the known solution, these contact elements are designed as flat plug connections, which are connected to the respective metal bands, for example by riveting or a Toxverbindung. In principle, it is also possible to form these connections directly on the sheet metal strip.

In order to ensure the electrical and mechanical contacting of the corrugated rib elements with the PCT resistance elements, the heating stages are braced by spring elements in a frame, so that even under unfavorable conditions, for example, strong vibrations and large temperature changes sufficient electrical and mechanical contact is ensured.

In the EP 1 327 834 B1 There is a further development of the radiator elements to the effect that the sheet metal strips / cover plates are crimped with the corrugated fin elements, so that a "popping" of the corrugated fin elements is reliably prevented and their installation compared to the solutions described above is significantly simplified because the unit of corrugated fin element with crimped cover plate dimensionally stable is and thus easier to handle than the flexible corrugated rib elements, which are connected by clamping (adhesion) with the cover plates.

Also in the EP 1 790 916 A1 radiator elements are described in which corrugated rib elements via metal strips - here contact plates called - are contacted.

Instead of a clamping connection, the radiator elements can also be glued or connected in any other way.

A disadvantage of the known solutions that for the preparation of the radiator elements a significant device-technical effort is required. Furthermore, the assembly is relatively complicated due to the stack structure with the insertion of the cover plates.

In contrast, the invention has for its object to provide a radiator element, running with such a radiator element heating stage and a method for producing a radiator element, by which the device complexity is reduced compared to the solutions described above.

This object is achieved with respect to the radiator element by the combination of features of claim 1, with regard to the heating stage by the features of the independent claim 7 and in terms of the method by the feature combination of the further independent claim 10.

Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, the radiator element is provided for a heater, in particular an air heater, and has at least one corrugated fin element, which forms a heat exchange surface and has a plurality of meander-shaped unfolded corrugated fins. The corrugated fin element is electrically connected to a contact element. According to the invention, this contacting takes place by means of a screw element, which is attached directly to the corrugated fin.

In other words, the contact element is screwed via the screw with the corrugated fin, so that no cover plate or the like must be provided for electrical contact. Due to the omission of these cover plates on the one hand the device complexity is significantly reduced compared to the solutions described above, on the other hand, the assembly is simplified, since the stack construction is much simpler than in the prior art.

Accordingly, the method according to the invention initially forms a corrugated fin element which has a multiplicity of meandering corrugated ribs and, in a subsequent operation, screwing a screw element which in turn is connected to a contact element in a pre-assembly step or is connected to this contact element after being screwed in. In this case, the screw is screwed directly into the corrugated fin element, so that it preferably passes through a plurality of corrugated fins. By this screw can be dispensed with the cover plates, so that the number of components of the radiator element is reduced and the assembly is simplified.

This screw can be designed as a self-tapping screw, so that eliminates the need to carry out a pilot hole. In principle, it is also possible to provide a pilot hole and then screw the screw.

The screw and the contact element can be cohesively connected to each other or else formed in one piece.

In particular, in solutions in which screw and contact element are not made in one piece, these can be provided after connection with an optimized depending on the application surface layer, such as a silver layer or a Teflon layer.

The mechanical stability of the corrugated fin element can be improved if at least one crimping lug is formed on each corrugated fin, which is then bent in the formation of the corrugated fin element, so that it engages around the adjacent corrugated fin. Such solutions are in the not yet published applications EP 12 158 839.6 and DE 10 2012 106 157.2 disclosed. The content of these applications belongs to that of the present application, so that with regard to details of this crimp connection, the description in the earlier applications can be used.

The attachment of the screw is simplified if this is made of a harder material than the corrugated fins. The material of the attached to the screw contact element can then be selected again with regard to an optimal contact.

Accordingly, the heating stage of the air heater according to the invention has at least two such radiator elements, between which at least one PTC resistance element is received, wherein the radiator elements and the resistance elements are electrically contacted. The connection can, as mentioned above, take place by bracing by means of a spring arrangement or else by gluing or the like.

In order to prevent overheating of the heating stages in the region of the contact elements, the nearest PTC resistance element may be slightly spaced from the contact elements. This spacing can be formed by a spacer ("dummy block") made of ceramic or heat-resistant plastic.

The feed when screwing the screw in the corrugated fin element is preferably selected so that a deformation of the corrugated fin element or more precisely their corrugated fins is minimized. This can be done for example by suitable guidance of the contact element or the screw, so that a deflection of the screw can be prevented during the screwing of the intended screw axis.

As will be explained in more detail below, the screw is preferably carried out with a kind of "screw head", which when screwed into abutment against the outer corrugated fin and thus ensures optimum contact. The contact can be improved in mechanical terms, if the screw is provided with a roughening, which improves the frictional engagement and thus the holding force.

Preferred embodiments of the invention and other possible developments are explained in more detail below with reference to schematic drawings. Show it:

1 a first embodiment of a heating stage according to the invention with two radiator elements according to the invention;

2 an assembly step in the manufacture of such a radiator element;

3 a detailed representation of a radiator element according to 1 ;

4 a screw and a contact element of the embodiment according to 3 in a raw state;

5 the arrangement according to 4 in the connected state;

6 . 7 and 8th Variants of contact elements with a screw according to 4 are connected and

9 a corrugated fin element for a further embodiment of a radiator element.

1 shows a heating stage 1 an air heater for the automotive sector. Such a heating stage 1 consists essentially of two radiator elements 2 . 4 between the heating elements, in the illustrated embodiment PTC resistor elements 6 are arranged. These are mechanical and electrical with the radiator elements 2 . 4 contacted. The radiator elements 2 . 4 serve on the one hand to increase the heat exchange surface with the air stream to be heated and on the other hand to power the PTC resistor elements 6 ,

Each of the radiator elements 2 . 4 has a corrugated fin element 8th Made from a variety of corrugated ribs 10 is formed, which are bent meander-shaped, so that in each case two adjacent corrugated fins 10a . 10b along to their vertices 12 adjacent investment areas 14 mutually abut each other. In these investment areas 14 are at every corrugated rib 10 crimp lugs 16 formed, this for mutual positional fixation of the corrugated fins 10 be bent over so that they are the adjacent corrugated rib 10 engage behind. To improve this facility can be attached to this adjacent corrugated fin 10 again a investment pocket 18 be formed on the the Crimplasche 16 rests after crimping. In this way, a very stable corrugated rib structure is obtained in which a bending of the corrugated fins / fins is reliably prevented.

The electrical contacting of the corrugated rib elements 8th (Power supply, current dissipation) via contact body 20 . 22 inserted in the lateral end sections (left in 1 ) of the respective corrugated fin element 8th are screwed in and doing several corrugated fins 10 prevail, being the axis 24 the contact body 20 . 22 closer to a vertex area of the respective corrugated fin element 8th is offset. In the embodiment according to 1 is the contact body 20 the radiator element 2 closer to the PTC resistor elements 6 arranged while the contact body 22 of the radiator element 4 closer to the in 1 lying below the vertices, that is arranged to the distant from the PTC resistor elements vertices. As will be explained in more detail below, these contact bodies 20 . 22 in the respective radiator element 2 . 4 screwed.

2 shows the radiator element 2 with the corrugated fin element 8th and the contact body 20 before this screwing. The corrugated fin element 8th is in the manner described above to increase the structural stability by means of the bent Crimplaschen 16 stabilized. The contact body 20 consists in principle of a contact element 26 and a screw 28 , which are preferably connected cohesively with each other. This will be explained in more detail below. The basic structure of the screw element 28 is similar to that of a self-tapping screw, with a screw thread 30 is designed as a self-tapping thread, so that it is not necessary in principle, a threaded hole or a pilot hole at the end portion 32 form, in the contact body 20 should be screwed. The screw element 28 is with a head 34 provided, with regard to the connection to the contact element 26 and in view of the optimum electrical contact with the corrugated fin element 8th is designed.

As will be explained in more detail later, the contact element 26 and the screw 28 are first executed as separate components and then connected via a suitable method, such as stud welding, soldering, friction welding or the like with each other. The contact body 20 is then via a suitable device in the end portion 32 screwed, wherein this device is designed so that the screwing takes place with a predetermined feed, which is chosen so that a deformation of the corrugated fins 10 is avoided.

3 shows the end section 32 of the radiator element 2 after screwing in the contact body 20 , You can see in this presentation quite well the Crimplaschen 16 , on both sides of the corrugated fins 10 are arranged and the wall of the adjacent corrugated fin 10a reach behind, each crimping bag 16 in a punched out 36 dips through the free cut of the attachment flap 18 is trained. These attachment tabs 18 are particularly clear at the end section 32 in 3 visible, noticeable. For further details of this crimping and stabilization of the corrugated fin structure, reference is made to the earlier applications mentioned above.

As already mentioned, the contact body 20 with its screw element 28 screwed without pre-drilling the corrugated fins, ie the screw 28 is a self-tapping / self-tapping screw with a tapered conical core 38 educated. At this core 38 , the screw head 34 and / or at the thread 30 suitable roughenings can be provided which limit the frictional engagement between the screw element 28 and the corrugated ribs 10 improve. Of course, additional securing means can be provided to the screw 28 Able to fix.

According to 3 extends the screw 28 over ten alternate vertices into the corrugated fin element 8th in; The depth of this screwing can be varied depending on the application. In the screwed state is the screw 28 along a peripheral portion of the screw head 34 on the inner peripheral wall of the resulting by screwing hole 40 The same applies to the areas in which the thread 30 is in threaded engagement with the corrugated fins, so that an optimal electrical and mechanical contact between the corrugated fin element 8th and the contact body 20 is guaranteed. As mentioned, the screwing takes place in such a way that the original corrugated fin structure is not or only minimally deformed, wherein such deformation when screwing through the stiffener by means of Crimplaschen / attachment tabs 16 . 18 is minimized. To improve the guidance during screwing, can on the screw 28 and / or on the contact element 26 suitable guide means are provided which allow a position positioning in the feed device. Thus, for example, a kind of "key surface" on the contact body 20 are provided, which is brought into positive engagement with a corresponding receptacle of the feed device.

4 shows the contact body 20 in a state in which the contact element 26 not yet with the screw 28 connected is. The screw element 28 is designed with respect to the choice of material and the geometry on the one hand so that the simplest possible, deformation-free screw connection with the corrugated fin element 8th can be produced. On the other hand, the geometry of the screw head 34 with regard to optimum contact with the corrugated fin element 8th and also the optimal connection with the contact element 26 designed. In the illustrated embodiment, the head 34 with a comparatively flat connection surface 42 executed, which is a simple cohesive connection with the contact element 26 allows. This can, for example, by stud welding with the head 34 get connected.

To further improve this connection is in the illustrated embodiment on the contact body 20 a radially extended radial collar 44 formed, which is also designed with a flat face, so that an optimal investment in the connection surface 42 is guaranteed.

To simplify the assembly can in the faces of the Radialbundes 44 and / or the connection surface 42 be provided centering or the like. To simplify the welding process, in particular the friction or stud welding, can at the connection surface 42 an increase 43 be provided.

The material of the contact element 26 can consist of various metallic materials, which can be followed by a suitable choice of geometry and the material of the customer's wishes for the respective connector or for the requirements for contacting the electronics. The screw element 28 is preferably made of a harder material than the corrugated fin element 8th executed, which is usually made of a comparatively soft aluminum alloy.

In principle, a galvanized steel or brass screw is used, whereby in the selection of the material and a good electrical and thermal conductivity should be kept in mind.

The connection between the contact element 26 and the screw 28 takes place, as indicated, for example by resistance welding, stud welding with tip ignition or by soldering.

In the illustrated embodiment, the contact element 26 of the contact body 20 designed as a contact pin, which is provided for example for contacting in a housing with an electronics.

5 shows the contact body 20 after the cohesive connection of the contact element 26 with the screw 28 , One recognizes that contact element 26 and screw element 28 are arranged coaxially to each other, wherein the radial collar 44 to the connection area 42 of the screw head 34 is scheduled. In order to improve the electrical contacting, after the cohesive connection, a two components ( 26 . 28 ) common coating, for example by silvering, are provided so that the contact body 20 is executed with a homogeneous, uniform surface. Instead of such a silvering, which improve the electrical contact would, for example, a coating of a PTFE material with embedded nickel to improve the screwing while maintaining the electrical conductivity can be provided.

To overheat the heating stage in the area of electrical contact (contact body 20 . 22 ), the PTC resistor elements can be reset in the connection area, so that the electrical discharge point (screw area) is not additionally connected via the PTC resistor elements 6 is overheated. For this purpose, for example, in this critical area a dummy block 46 (please refer 1 ) are provided, which is used in place of a PTC resistor element. This dummy module 46 is then together with the PTC resistor elements 6 by clamping, gluing or otherwise with the radiator elements 2 . 4 mechanically connected.

6 shows a variant of the contact body 20 in which the contact element 26 is designed as a flat plug, wherein the insertion plane of the tab is located approximately in the plane in which the screw axis of the screw 28 is arranged.

7 shows a variant with designed as a flat plug contact element 26 this being with a connecting leg 48 is formed, which extends at right angles to the insertion plane of the tab and on the large surface of the screw 28 is scheduled. Accordingly, in the embodiment according to 7 the flat connector axis offset from the screw axis.

8th shows a variant of a contact body 20 in which the contact element 26 as a double flat connector with two flat connector sections 26a . 26b is executed by means of a base 50 are connected to each other, so that the contact element 26 U-shaped. To the outside large area of this base 50 then is the center of the screw 28 set so that both tab levels are offset from the screw axis.

In the embodiments explained above, the corrugated rib elements are 8th the radiator elements 2 . 4 over the Crimplaschen 16 and possibly the attachment tabs 18 stiffened. However, the invention is by no means limited to such an embodiment but can also be used in conventional corrugated rib structures, as described, for example, in US Pat 9 is shown. In such a corrugated fin element 8th are the corrugated fins, similar to the embodiment described above meandering folded, in this embodiment, the investment areas 14 that are adjacent to the crests 12 are arranged significantly smaller than in the embodiment described above, since no connection via the tabs 16 . 18 he follows. It is thus a corrugated rib structure, as used in the prior art described above. Since such corrugated fins in the unassembled state, ie in not yet with the PTC resistor elements 6 glued or jammed state are relatively unstable, it may be advantageous in the end section 32 to provide a pilot hole, the insertion of the screw 28 facilitates and reduces the risk of deformation of the corrugated fin structure. In principle, however, it is also possible with suitable feed selection, such a conventional corrugated fin structure with a self-tapping screw 28 to provide.

The above-described solutions in which the electrical contacting of the radiator elements 2 . 4 by screwing a contact body in the respective corrugated fin element 8th takes place, is characterized by a very simple structure, since it can be dispensed with the cover sheets used in conventional solutions. Another significant advantage is that the flow-through cross-section is reduced only slightly by the screw, so that the pressure drop when flowing through the radiator element is minimal. Furthermore, such a solution can be easily adapted to different requirements by suitable choice and design of the contact elements and the screw. The solution according to the invention can, as stated, be used in high-voltage and low-voltage applications, in particular in automotive applications, but also for industrial applications, such as cabinet heaters, auxiliary heaters for low-energy houses, etc. The described contact bodies can be used for different corrugated rib structures, so that a modular structure simple way is feasible.

Disclosed are a radiator element for an air heater, a heating stage of such an air heater and a method for producing a radiator element, in which a corrugated fin element is electrically contacted directly by screwing a contact body.

LIST OF REFERENCE NUMBERS

1

 heating stage

2

 radiator element

4

 radiator element

6

 PTC resistive element

8th

 Corrugated fins element

10

 corrugated fin

12

 vertex

14

 plant area

16

 Crimplasche

18

 application tab

20

 Contact body

22

 Contact body

24

 axis

26

 contact element

28

 screw

30

 thread

32

 end

34

 screw head

36

 punching

38

 core

40

 drilling

42

 bonding surface

43

 increase

44

 radial collar

46

 dummy block

48

 connecting leg

50

 Base

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 0350528 B1 [0003, 0005]
• EP 1327834 B1 [0007]
• EP 1790916 A1 [0008]
• EP 12158839 [0020]
• DE 102012106157 [0020]

Claims (14)

Radiator element for an air heater, comprising at least one corrugated fin element providing a heat exchange surface (US Pat. 8th ) with a plurality of approximately meander-shaped curved corrugated fins ( 10 ), which is electrically connected to a contact element, characterized in that the contact element ( 26 ) by means of a screw element ( 28 ) to the corrugated fin element ( 8th ) is set. Radiator element according to claim 1, wherein the screw element ( 28 ) is a screw that has several corrugated fins ( 10 ) penetrated frontally. Radiator element according to claim 1 or 2, wherein the screw element ( 28 ) is self-fulfilling. Radiator element according to one of the preceding claims, wherein the screw element ( 28 ) and the contact element ( 26 ) are integrally formed or materially connected to each other. Radiator element according to one of the preceding claims, wherein contact element ( 26 ) and screw element ( 28 ) are provided with a common surface layer. Radiator element according to one of the preceding claims, wherein adjacent corrugated fins ( 10 ) with each other, preferably by Crimplaschen ( 16 ) are connected. Radiator element according to one of the preceding claims, wherein the screw element ( 28 ) of a harder material than the corrugated fin element ( 8th ) is trained. Heating stage of an air heater with at least two radiator elements according to one of the preceding claims, between which PTC resistance elements ( 6 ) received via the radiator elements ( 2 . 4 ) are electrically contacted. Heating stage according to claim 8, wherein a screw element side PTC resistance element ( 6 ) is reset. Heating stage according to claim 8 or 9, wherein the connection of the radiator elements ( 2 . 4 ) and the PTC resistor elements ( 6 ) cohesively or by bracing. Method of producing a radiator element comprising the steps of: producing a corrugated fin element ( 8th ), which has a plurality of meandering corrugated ribs ( 10 ) and screwing one with a contact element ( 26 ) can be brought into operable or operatively connected screw element ( 28 ) such that it has at least one corrugated fin ( 10 ) penetrated frontally. Method according to claim 11, wherein the contact element ( 26 ) and the screw element ( 28 ) are materially connected or executed in one piece. Method according to claim 11 or 12, wherein adjacent corrugated fins ( 10 ) are joined together, preferably by crimping. Method according to one of the claims 10 to 13, wherein when screwing in the screw element ( 28 ) a feed is selected such that a deformation of the corrugated fins ( 10 ) is minimized.

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