EP1545157B1 - Tube and process for compression-fitting of functional elements in such a tube - Google Patents

Abstract

Method for clamping PTC heating elements etc. in hollow holder (1), such as tube, with two concave ceiling wall region (1.5,1.6) opposite to each other and to flat sides of PTC heating elements (2). PTC heating elements are clamped by pressure application to further side walls, orthogonally to ceiling wall regions. Preferably side walls are pressurised in direction of their surface normal. Pressure application typically reduces spacing of side walls in application direction, with regions of side walls providing clamping of PTC elements. Independent claims are included for tube holding PTC heating elements and its use and heater.

Description

The invention relates to a method for clamping functional elements in a hollow receiving means, such as a tube with two mutually and flat sides of the functional elements opposite, at least partially concave top wall areas. Furthermore, the invention relates to a pipe, in particular for receiving functional elements, such as PTC heating elements, with two mutually and flat sides of the functional elements opposite, at least partially concave top wall areas. Furthermore, the invention relates to uses of such a tube.

Electric heaters, in which resistance heating elements in the form of PTC elements are used for generating a heating power, are known today in a variety of fields of technology, for example in the automotive industry. There, the said heaters are used, for example, for heating vehicle interiors, as long as alternative heating methods using the engine cooling water as the heating medium due to insufficient engine heating not yet working efficiently. In this case, the electric heater can be carried out both separately be integrated as well as in a flowing through the cooling water fins / tube block, for example, by a part of the cooling water-flowed tubes is replaced by PTC tubes. With such heaters, individual PTC elements are regularly arranged in hollow receiving means, such as profile tubes, which are plastically deformed to clamp the PTC elements by pressurizing their cover walls. For this purpose, according to the state of the art, by means of a suitable tool, two opposing cover walls exert a compressive pressure on the hollow receiving means, so that correspondingly an inner spacing of the cover walls decreases until they come into contact with the PTC elements received in the receiving means and set this.

A generic tube for use with an electrical heating element is known from US 4,942,289. This heating element comprises a contact unit formed from at least one PTC element and contact plates resting on both sides thereof and a tubular housing, wherein the housing, when not pressed, has an inner wall facing convexly facing the contact arrangement with a finite radius of curvature. In the subsequent mechanical pressing a spring tension is built up, which is present as a pressing force on the contact surfaces of the PTC elements.

It is to be regarded in particular as disadvantageous that after a relief of the press used, the deformed cover walls of the receiving means inevitably spring back to a certain extent due to an existing partial elasticity, so that a holding force for the PTC elements decreases. Furthermore, for plastic deformation of the receiving means comparatively high pressing forces in an equivalent order of magnitude of 40 tons required, which further requires a complex structure of the pressing tools to be used.

In addition, in addition to the above-described heating tubes (receiving means and PTC elements), said heating devices regularly have heat-emitting fins in the form of fins or the like, which are connected to the heating tubes in a manner which is highly thermally conductive. In the case of the previously known heating devices or methods for their production, the lamella assembly must take place in a subsequent, additional process step, resulting in disadvantageously long production times and corresponding cost increases.

The invention has for its object to provide a method and a profile tube, which can overcome the disadvantages enumerated above.

According to the invention this object is achieved in a method of the type mentioned above in that the functional elements are braced by pressurizing the substantially perpendicular to the concave top wall areas extending side walls. The object is also achieved by a tube, which is characterized by further substantially perpendicular to the concave top wall portions extending further side walls, which are acted upon to reduce a clearance between the retracted top wall portions with a compression pressure.

The pressurization or the action of a compressive force is thus substantially perpendicular to the flat sides of the functional elements, exactly perpendicular to its surface normal to the other side walls - if they are flat - and exactly perpendicular to the flat sides of the functional elements stand, which does not have to be, then parallel to the surface normal of the other side walls. By this pressure or force the first partially concave preformed top walls are pressed against the functional element, so that this is braced in the pipe.
In this way, only a small pressing force is required according to the invention for clamping the receiving means (tubes), since no plastic deformation has to be achieved in the pressing direction. Accordingly, the tools to be used are simple.

According to a preferred embodiment of the method, it is provided that the side walls are pressurized substantially in the direction of their surface normal, wherein accordingly the tube is preferably formed such that the side walls are pressurizable substantially in the direction of their surface normal. The statement that the pressurization takes place substantially in the direction of the surface normal of the side walls, in particular, that the forces exerting the pressurization forces have a predominant or main component parallel to the surface normal of the side walls, although the forces are not exactly parallel to the surface normal.

In the course of the inventive method, the clamping of the functional elements is preferably such that the pressurization reduces a clear distance between the opposing top walls, with regions of the concave top wall areas approaching one another for clamping the functional elements. During a It is provided in an extremely preferred embodiment that a distance between partial sections of at least one concave top wall area is reduced by the application of pressure and that between these at least one attachment part, such as a metal lamella or rib, is permanently clamped. It is possible in this way to integrate the attachment of attachment parts in the pressing process.

In a further development of the profiled tube according to the invention, it is provided that, by means of cover walls of the retracted cover wall regions, an outwardly widening free space region with essentially an isosceles trapezoidal cross-section is defined prior to pressurization. The free space area is preferably designed to accommodate at least one complementary end area of at least one attachment part, such as a metal lamella or rib. In an extremely preferred embodiment of the profile tube according to the invention, the attachment part is substantially positively enclosed after pressurization by the cover walls of the concave top wall area and held in this way by clamping. Thus, a composite device to be produced using the profile tubes according to the invention, such as a heater, with the already mentioned heat transfer ribs in the course of bracing the PTC elements in only one process step produced.

For secure holding of the attachment parts can furthermore be provided that define the cover walls of the retracted top wall areas after pressurization undercuts for receiving complementary corner regions of the attachment part. Due to the low pressing forces required, in addition to the prior art, longitudinally ribbed profiles can be processed, which have hitherto been built up regularly in a complex manner from two separate half profiles. Correspondingly, in a preferred development, the profile tube according to the invention has rib elements in at least one of the cover or side wall regions which preferably have an extension component in the longitudinal direction of the profile tube. For optimal heat dissipation, the rib elements may also have an extension in cross-section substantially perpendicular to a local course of the cover and / or Have sidewall areas or the top and / or side walls.

The above-described profile tubes are generally suitable for providing a composite device of a number of profile tubes and connecting connecting parts, wherein the attachment parts are held by the profile tubes, and are preferably used in a radiator with an arrangement of heat-dissipating fins.

Fig. 1

einen Querschnitt durch ein erfindungsgemäßes Profilrohr mit eingebrachtem PTC-Heizelement vor dem Verpressen;

Fig. 2a

einen weiteren möglichen Querschnitt eines erfindungsgemäßen Profilrohrs;

Fig. 2b

eine weitere Querschnittsansicht des Profilrohrs gemäß Fig. 2a mit eingezogenen Deckwand-Bereichen und eingebrachtem PTC-Element ;

Fig. 3a

ein erfindungsgemäßes Profilrohr mit eingebrachtem PTC-Element und Ansatzteilen vor dem Verpressen;

Fig. 3b

das Profilrohr der Fig. 3a nach erfolgtem Verpressen;

Fig. 4a

eine Seitenansicht des erfindungsgemäßen Profilrohrs gemäß der Fig. 3b;

Fig. 4b, c

Längsschnitte durch alternative Ausgestaltungen eines erfindungsgemäßen Profilrohrs gemäß der Fig. 3b;

Fig. 5a

einen Querschnitt durch einen unter Verwendung erfindungsgemäßer Profilrohre aufgebauten Heizkörper;

Fig. 5b

eine Seitenansicht des Heizkörpers der Fig. 5a; und

Fig. 6a,b

einen weiteren möglichen Querschnitt eines erfindungsgemäßen Profilrohrs vor bzw. nach dem Verpressen.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. Show it:

Fig. 1

a cross section through an inventive profile tube with inserted PTC heating element before pressing;

Fig. 2a

a further possible cross section of a profile tube according to the invention;

Fig. 2b

a further cross-sectional view of the profile tube of Figure 2a with retracted top wall areas and incorporated PTC element.

Fig. 3a

an inventive profile tube with incorporated PTC element and attachment parts before compression;

Fig. 3b

the profile tube of Figure 3a after completion of pressing.

Fig. 4a

a side view of the profile tube according to the invention according to FIG. 3b;

Fig. 4b, c

Longitudinal sections through alternative embodiments of a profile tube according to the invention according to FIG. 3b;

Fig. 5a

a cross section through a constructed using profile tubes according to the invention radiator;

Fig. 5b

a side view of the radiator of Fig. 5a; and

Fig. 6a, b

a further possible cross section of a profile tube according to the invention before or after the pressing.

The invention will be described in the following with reference to a number of exemplary embodiments, which relate in particular in the form of to profile tubes for use in electric heaters. However, it should be emphasized that the method according to the invention or the profile tube according to the invention are not limited to such applications, but can generally be used wherever functional elements are to be clamped inside a hollow receiving means.

Fig. 1 shows an extruded, inventive profile tube 1 with a substantially rectangular cross-section. Inside 1.1 of the profile tube 1, a flat PTC heating element 2 consisting of a PTC resistor 2.1, a contact track 2.2, a ceramic insulation 2.3 and a contact frame 2.4 is arranged. The PTC heating element 2 in particular has flat sides 2a, 2b. The structure of such PTC elements 2 is familiar to the person skilled in the art and is not the subject of this invention per se.

The profile tube 1 according to the invention has top wall portions 1.2, 1.3 which are retracted inwardly relative to a strictly rectangular cross-section of the profile tube 1, i. show a concave training. By retracted top wall portions 1.2, 1.3 of the profile tube 1 are outwardly expanding free space areas 1.4 defined, of which in Fig. 1 by way of example only one dashed line is shown. The cover walls 1.5, 1.6 of the profile tube 1 have in the retracted, concave top wall portions 1.2, 1.3 an inner distance a, which is greater than a corresponding dimension a 'between the flat sides 2a, 2b of the PTC element 2. Furthermore, the Profile tube 1 further side walls or side wall portions 1.7, 1.8, which extend substantially perpendicular to the concave top wall portions 1.2, 1.3 and whose clear distance b is greater than a corresponding dimension b 'of the PTC element 2, where: (b-b ')> (a-a').

In the illustrated embodiment of Fig. 1, the profile tube 1 according to the invention also has along its outer contour rib members 3, which are perpendicular to the plane of the drawing, i. extend in the profile longitudinal direction and are aligned in cross section substantially perpendicular to a local extension direction of the cover and side walls 1.5-1.8.

The clamping of the PTC element 2 in the interior 1.1 of the profile tube 1 according to the invention is carried out by lateral pressure (arrows P) on the side walls 1.7, 1.8. This will be explained in more detail below with reference to FIGS. 3a, b.

2a, b show a further possible embodiment of the profile tube 1 according to the invention, here initially (FIG. 2a) as a seamlessly drawn or welded tube with a circular cross section, which, as shown in FIG. 2b, for forming concave top wall regions 1.2, 1.3 (see Fig. 1) is to profile accordingly, for example using a suitable roller system (not shown here).

Fig. 3a, b show in detail the already mentioned pressing process by pressurization (arrows P) of the side walls 1.7, 1.8 of the profile tube according to the invention 1. This is according to Fig. 3a, b substantially as already explained in Fig. 1, has but no ribs on. In the area of the retracted, concave top wall portions 1.2, 1.3 formed free spaces 1.4 (see Fig. 1) are used in the subject of Fig. 3a, b respectively neck portions 4 in the form of flat metal fins. Starting from a main body 4.1, these have an end region in the form of a projection 4.2, which first tapers conically in a first region 4.2a adjoining the main body 4.1 and subsequently widens slightly conically in a second region 4.2b, so that in FIG Area of a peak 4.2c of the projection 4.2 4.2d corners are formed. A length L of the projection 4.2 is dimensioned larger than a insertion depth T of the top wall portions 1.2, 1.3, so that the attachment part 4 with its projection 4.2 in the free space area 1.4 can be introduced, the tip 4.2c each side wall 1.5, 1.6 touched without the main body 4.1 of the attachment part 4 in turn already with the side walls 1.5, 1.6 of the profile tube 1 comes into contact.

In Fig. 3b, the arrangement of Fig. 3a is shown again after the application of pressure P. The pressing pressure P first causes the pressurized side walls 1.7, 1.8 to move towards each other while reducing their spacing b (FIG. 1). At the same time due to effective in the top walls 1.5, 1.6 each inwardly directed forces of the indentation in the top wall areas 1.2, 1.3, until a = a 'deepens (Fig. 1), so that the PTC element 2 inside 1.1 of the profile tube 1 via its flat sides 2a, 2b between the top walls 1.5, 1.6 is clamped and clamped. The latter are in this case formed slightly convexly curved to form the largest possible contact surface for heat transfer with the PTC element 2 via its flat sides 2a, 2b on their inner sides 1.5a, 1.6a (cf., Fig. 1, 3a). At the same time, convexities 1.9 of the cover walls 1.5, 1.6 are formed in the retracted, concave top wall areas 1.2, 1.3, so that the formerly trapezoidal free space area 1.4 (cf., FIGS. 1, 3a) now has undercuts 1.10. This results in a form-fitting engagement of the attachment part 4 in the area of the projection 4.2 (corners 4.2d) and the bulges 1.9 or undercuts 1.10 in the top wall areas 1.2, 1.3, as shown in FIG. 3b, so that the attachment part 4 clamps on the profile tube 1 is held. The slightly S-shaped course of the cover walls 1.5, 1.6 in the region of the bulge 1.9 or undercut 1.10, which is also recognizable in FIG. 3b, also makes it possible to compensate for height differences and / or tolerances of both the PTC element 2 and of the spring due to a certain spring effect Profile tube 1.

Due to the preformed confiscation of the cover walls 1.5, 1.6 of the profiled tube 1 shown in FIGS. 1, 2b, 3a, in the context of the invention, a significantly reduced pressure P compared with previously known methods is sufficient for the connection between the attachment parts 4 and 3 shown in FIG to produce the profile tube 1, wherein also the distortion of the PTC elements 2 and the assembly of the attachment parts 4 done in one and the same step. The already mentioned S-shaped course of the cover walls 1.5, 1.6 after pressurization P further causes the profile tube 1 according to the invention after elimination of the pressurization P, ie after removal of a corresponding pressing tool (not shown) due to a stored clamping force in the material no longer automatically can open (self-locking). In this way, a significant of the initially listed disadvantages of corresponding previously known methods or devices is reliably avoided.

4a shows a side view of the profile tube 1 according to the invention according to the Fig. 3a, b with a plurality of mutually parallel aligned attachment parts 4 in the form of metal lamellae. FIGS. 4b, c show sections through a profile tube-lamella arrangement according to FIG. 4a. The embodiments according to FIGS. 4b and 4c differ in that the attachment parts 4 shown in FIG. 4c in the outer region 4.2b of the projection 4.2 have a substantially rectangular bend 4.2e, through which a heat-conducting contact between the attachment parts 4 and the profile tube 1 can be improved.

In FIGS. 5a, 5b it is shown how a number of profile tubes 1 according to the invention with inserted PTC elements 2 can be connected to an assembled device via an arrangement of attachment parts 4, in the exemplary embodiment shown specifically to a heating element 5. In terms of process technology, the overall structure of the heating element 5 shown in FIGS. 5a, b can be assembled beforehand and still be kept unstressed by means of a suitable holding tool (not shown). Subsequently, the bracing of the entire heater 5 by pressurizing the side walls 1.7, 1.8 of the profile tubes 1 in a single operation, as shown above with reference to FIGS. 1, 2b, 3a.

Finally, Figures 6a, b show a further embodiment of the profile tube 1 according to the invention before or after the pressing (pressurization P, Figure 6a). The concave configuration of the cover walls 1.5, 1.6 results from a cross-sectional two-legged construction with legs 1.5b, 1.5c and 1.6b, 1.6c, which include an obtuse angle α before pressing. The side walls 1.7, 1.8 and the legs 1.5b, 1.6b are arranged in pairs at a slightly obtuse angle to each other. As a result, zakkenartige projections 3 'are formed by the side walls 1.7, 1.8 and the legs 1.5c, 1.6c (Fig. 6a).

When lateral pressure is applied, the legs 1.5c, 1.6c, reducing the angle α (Fig. 6a) to about 90 ° (angle α ', Fig. 6b) to the side walls 1.7, 1.8, in turn, the clearances between the side walls 1.7, 1.8 and between the top walls 1.5, 1.6 or their legs 1.5b, 1.6b decrease, so that according to the invention functional elements (not shown here) can be tense in the interior 1.1 of the profile tube 1. The protrusions 3 "of FIG. 6b, which result from the protrusions 3 'of FIG. 6a, can be understood and used as rib elements (see reference 3 in FIG.

LIST OF REFERENCE NUMBERS

1

section tube

1.1

inner space

1.2, 1.3

Retracted top wall area

1.4

free space area

1.5, 1.6

top wall

1.5a, 1.6a

inside

1.5b, c

leg

1.6b, c

leg

1.7, 1.8

Side wall

1.9

bulge

1.10

undercut

2

PTC heating element

2.1

PTC resistor

2.2

contact track

2.3

insulation

2.4

contact frame

3

rib element

3 ', 3 "

head Start

4

Attachment part, metal lamella

4.1

main body

4.2

head Start

4.2a, b

Area

4.2c

top

4.2d

corner

4.2e

turn

5

radiator

a

distance

a '

dimension

b

distance

b '

dimension

L

length

P

injection pressure

T

depth

α, α '

angle

Claims (16)

1. Method for bracing functional elements in a hollow receiving means (1) with two at least partly concave cover wall areas (1.5, 1.6) facing one another and the flat sides of the functional elements (2-2.4), characterized in that the functional elements (2-2.4) are braced by pressurizing the further side walls (1.7, 1.8) extending substantially perpendicular to the concave cover wall areas (1.5, 1.6).
2. Method according to claim 1, characterized in that the side walls (1.7, 1.8) are pressurized substantially in the direction of their surface normal.
3. Method according to claim 1 or 2, characterized in that through the pressurization there is a reduction to the inside clearance of side walls (1.7, 18) subject to pressurization, the areas of the concave cover walls (1.5, 1.6) approach one another for clamping the functional elements (2-2.4).
4. Method according to one of the claims 1 to 3, characterized in that through the pressurization a clearance between portions (1.5a, 1.6a, 1.5b, 1.6b) of at least one of the concave cover wall areas (1.5, 1.6) is reduced and between the same is permanently clamped at least one attached piece (4), such as a metal lamina or corrugated rib.
5. Tube (1) for receiving functional elements, having two at least partly concave cover wall areas (1.2, 1.3) facing one another and the flat sides (2a, 2b) of the functional elements, characterized by further side walls (1.7, 1.8) extending substantially perpendicular to the concave cover wall areas (1.2, 1.3) and which can be pressurized with a pressure (P) for reducing an inside spacing (a) between the concave cover wall areas (1.2, 1.3).
6. Tube according to claim 5, characterized in that the side walls are pressurizable substantially in the direction of their surface normal.
7. Tube according to claim 5 or 6, characterized in that through cover walls (1.5, 1.6) of the concave cover wall areas (1.2, 1.3) prior to pressurization (P) is defined an outwardly widening, free space area (1.4) with a cross-sectional essentially corresponding to an equal-sided trapezium.
8. Tube according to one of the claims 5 to 7, characterized in that the free space area (1.4) is constructed for receiving at least one complimentary end region (4.2) of an attached piece (4), such as a metal lamina or corrugated rib.
9. Tube according to claim 8, characterized in that the cover walls (1.5, (1.6) of the concave cover wall areas (1.2, 1.3) substantially positively surround the end region (4.2) of attached piece (4) after pressurization (P), so that clamping retention thereof takes place.
10. Tube according to one of the claims 5 to 8, characterized in that the cover walls (1.5, 1.6) of the concave cover wall areas (1.2, 1.3), following pressurization (P), define undercuts (1.10) for receiving complimentary corner regions (4.2d) of attached piece (4).
11. Tube according to one of the claims 5 and 6, characterized in that the cover and/or side walls (1.5-1.8) have rib elements (3).
12. Tube according to claim 11, characterized in that the rib elements (3) have an extension component in the longitudinal direction of tube (1).
13. Tube according to claim 11 or 12, characterized in that cross-sectionally the rib elements (3) have an extension substantially perpendicular to a local path of the cover and/or side walls (1.5-1.8).
14. Use of a tube according to one of the claims 5 to 13 for creating a composite device (5) from a plurality of tubes (1) and attached pieces (4) for connecting the same, the attached pieces (4) being retained by the tubes (1).
15. Use of a tube according to one of the claims 5 to 14 in a heater (5) with an arrangement of heat emission ribs (4).
16. Heater with an arrangement of heat emission ribs, characterized by a plurality of tubes (1) according to one of the claims 5 to 15.

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