ES2575134T3 - Electric heater - Google Patents

Abstract

Electric heater, which is inserted with a heating section (2) in a housing of a component to be thermostatically regulated, with heating elements (34, 36) supplied with current through power supply lines (14, 16 ), which can be placed directly or indirectly in thermal contact with a wall of the housing, characterized by an activation pin (20), which can be moved from a release position to an activation position, to move the heating elements (34, 36) from a mounting position, in which they are not or are only in small measure in thermal contact with the wall or in electrical contact with the power supply lines (14, 16) associated, to an active position, in the that the thermal contact and / or the electrical contact is guaranteed, the heater having at least two heating elements (34, 36) facing each other, to which it is associated in each case a spring element (52, 54), the activation pin (20) being put in its activation position between both spring elements (42, 44), to request the heating elements with an elastic pretension in the direction of the wall or in the direction of a contact.

Description

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DESCRIPTION

Electric heater

The invention relates to an electric heater according to the preamble of claim 1.

This type of electric heaters can be used for example in the blow-by system of combustion engines or to heat a tank of an RCS system (selective catalytic reduction). On the website
www.dbk-group.de are examples of this type of electric heating. According to them, they have a heating section, which is inserted into a correspondingly shaped housing of the component to be thermostatically regulated, for example a reservoir or a flow path of the blow gas. This heating section is extended with a plug or contact part, in which the power supply lines for the heater are arranged. In the known heaters, resistance elements are used, for example PTC heating elements, which are supplied with current through the power supply lines of the contacting part and are adjacent, as far as possible by the entire surface, to a wall area of the housing section, so that heat is transmitted directly through the wall of the heating section and the adjacent wall of the component to be thermostatically regulated. In this regard it is important that, in order to improve heat transmission, a large area of thermal exchange is present on the one hand and that no insulating air space is also provided in the heat transmission path.

In this regard, it is problematic that, due to manufacturing tolerances and temperature fluctuations in the operation of the heater or of the component to be heated, an insulating air gap can be produced in the area where the heating element is adjacent to the wall. This disadvantage can be ruled out when the areas to be held by the heating elements are adjusted to perfection, but then the assembly of the heater is relatively complicated due to the required perfect fit dimensions, so that in particular with use of PTC modules there is a risk that the heating element will be damaged.

From US 5 262 619 A a heating device for heating flowing media is known, which has a heat exchanger that can be heated by means of PTC resistors, which includes a recess-like cavity. A parallelepiped shaped substrate body is adapted in its shape to the shape of the cavity and can be introduced therein. The surfaces of the substrate body have recesses for the housing of the PTC resistors and a contact spring. The surfaces directed towards each other of the substrate body and the cavity are chamfered from the introduction side inwards.

In EP 1375997 A a solution is disclosed in which a heating section is pressed against a face of the component to be heated, so that heat transmission occurs in the adjacent area on one side of the section of heating. Such a solution has the disadvantage that the heat exchange area is reduced, and therefore the possible heat input to the component is reduced due to the reduced power density.

In contrast to this, the invention is based on the objective of creating an electric heater in which an optimal heat transmission with a simple assembly is guaranteed.

This objective is achieved by means of an electric heater with the characteristics of claim 1.

Advantageous improvements of the invention are subject to the dependent claims.

The electric heater according to the invention has a heating section, which can be inserted into a housing of a component to be thermostatically regulated. The heater also has heating elements supplied with current through power supply lines. According to the invention the heater is made with an activation pin, which can be moved from a release position to an activation position. In the release position, the respective heating element is in a mounting position with play, in which the heating element is not or is only irrelevant in thermal contact with the wall or in electrical contact with the lines of power supply With the movement of the activation plug to the activation position, the heating element or the power supply line is moved to an active position, in which the thermal and / or electrical contact is established essentially without play and by whole surface

With the solution according to the invention, a heater is therefore created, in which the heating elements are initially located, with play, in a non-compact manner, adjacent to the wall to be heated or to the power supply lines. For activation of the heater, the activation pin is then moved, so that the heating elements move or push into their active position. This essentially simplifies the assembly of the heater, since the heating elements are initially housed with a relatively large clearance in the housing. In the activation position of the activation pin, this game is

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then canceled, so that the desired thermal and electrical contact is established with a very good heat transfer.

The thermal and / or electrical contact established thanks to the displacement of the activation pin is preferably also accompanied by a mechanical contact, which ensures that the heating elements are pressed against the corresponding wall of the component housing. Mechanical contacting can occur additionally to, or independently of, thermal and electrical contacting. In this respect, the mechanical contacting of the heating elements can occur indirectly, that is to say through interposed construction elements, or directly.

In the invention, the heater has at least two heating elements facing each other, a spring element is associated in each case, the activation pin lying in its activation position between both spring elements, to request the heating elements. heating by means of the spring force in the direction of the wall or in the direction of contact. In the first variant, two heating elements can therefore be pressed against walls, facing each other, of the housing of the component to be heated, so that, thanks to the improved heat transmission area with respect to the state of the technique cited in the Introduction of the description, a considerably improved heat input with higher power density can be implemented.

In an exemplary embodiment of the preferred invention, the activation pin has an activation projection that is cantilevered from a housing section and an activation section on the side of the heating element, which enters into active connection with the control element. heating for the activation of the heater by means of the displacement of the activation projection, the activation pin being able to be located directly or indirectly adjacent to the heating element.

It is also advantageous that, with the activation pin located in the release position, no complementary electrical plug can be plugged in. This implements a simple security measure against incorrect use.

The heater structure is especially simple when at least one of the power supply lines is configured with a spring element, which in the active position of the activation pin requests the heating element in the direction of the wall.

In a variant of the invention, a spring element is attached to a power supply line. This can be retained, for example, by means of tightening tabs of the power supply line.

In an example of embodiment of the invention, at least one of the power supply lines is configured with spring elasticity, so that by means of the spring action tolerance deviations can be compensated and a contiguous arrangement is guaranteed over the entire surface of the heating element in its active position.

The power supply line can have an approximately U-shaped structure, a concave bulge that provides the spring action being configured on a U-base.

According to the invention it is preferred that both power supply lines are configured with spring elasticity and / or with spring elements, through which at least one heating element in the direction of its active position can be requested, for example, in each case. .

A variant of the invention provides that four heating elements are provided, facing two to two, and between which spring elements and an activation pin are arranged.

The activation pin can be made of metal, as a curved die cut piece with a retracted activation section, or plastic.

In a refinement of the invention, the activation pin is fixed in place in its activation position by hooking, by dragging force or shape, with another construction element of the heater, for example the plug part mentioned above.

This fixation in place can take place, for example, by interlocking, with which a tongue fits into a recess of the activation pin or, kinematically in reverse, a projection of the activation pin fits into a recess of the plug part or of another fixed heater housing section.

According to the invention it is preferred that the electric heater is made of PTC resistor elements.

It is also advantageous in the described embodiment that the heater can be disassembled again. After deactivation of the activation plug, the heater can be removed without force and can be replaced by

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example in case of breakdown. In this regard, however, care must be taken that the heater is not removed arbitrarily. In this case it is practical to use a special tool.

An example of embodiment of the preferred invention is explained in more detail below with the help of schematic drawings. They show:

Figure 1 a three-dimensional view of an electric heater according to the invention;

Figure 2 a top view of a heater according to Figure 1;

Figure 3 the heater of Figure 1 without insulating sheet;

Figure 4 a plug part of the heater of Figure 1;

Figure 5 a three-dimensional view of the heater according to Figure 1 without housing;

Figure 6 the arrangement according to Figure 5 in another view;

Figure 7 a side view of the heater of Figure 1 without housing;

Figure 8 an individual representation of a first power supply line of the heater according to Figure 1;

Figure 9 an individual representation of a heater spring element of Figure 1; Figure 10 an individual representation of a heater activation pin of Figure 1; Figure 11 an individual representation of a second power supply line of the heater of Figure 1 and

Figure 12 the heater of Figure 1 inserted into a cavity.

Figure 1 shows a view of a heater 1, which in principle consists of a heating section 2 and a plug part 4. As will be explained in more detail below, in this plug part 4 the power lines are arranged of current for bringing the heater into contact 1. The heating section 2 is inserted into a housing or cavity of a component to be heated, for example an RCS tank, the heating section 2 being adjacent, all over the surface , to the wall of this housing, so that a good heat transfer is guaranteed. In the exemplary embodiment shown, an electrically non-conductive insulating sheet 6 that optimizes heat transfer is provided in the area adjacent to the housing not shown in the heating section 2, which will be described in more detail below. A plug contour is incorporated in the area of the plug part 4, to which a correspondingly profiled plug-in connection of the electrical supply is applied, this plug contour 8 being made in such a way that a correct orientation assembly is guaranteed .

Figure 2 shows a top view of the plug part 4 of Figure 1. A plug flange 10 is recognized, which in the view according to Figure 2 covers the heating section 2 and also acts as an introduction limit for the same. The profiled plug part 4 surrounds a peripheral wall 12 with a peripheral wall, in which the above-mentioned plug is inserted into the power supply at least in sections. At the bottom of this plug space 12 two power supply lines 14, 16 of the heating section 2 are recognized, in the form of tabs that enter therein, and an activation projection 18 of an activation plug 20 , which also enters, in cantilever, in this plug space 12. This activation projection 18 is supported by two spring tongues 22, 24 of the plug part 4 and extends through the bottom of the plug space 12 and entering in the heating section 2. The spring tabs 22, 24 have in each case an interlocking projection, which is inserted in notches 26, 78 of the activation pin 20. In the release position of the activation pin 20, the spring tabs 22, 24 are engaged in the notch 78 of the activation pin 20, so that it is fixed in place against an error movement. If the activation projection 18 with a pushing force is requested, in the representation according to figure 2 from the viewpoint of the observer, then the spring-elastic coupling of the spring tabs 22, 24 is released, so that the activation pin 20 can move in the direction of the heating section 2. In the active position the spring tabs 22, 24 are then engaged in the notch 26 of the activation pin and locked. This function will be explained in more detail below.

Figure 3 shows the heater 1 according to Figure 1 with the insulating sheet 6 removed. In this way the heating section 2 itself can be seen, which will be explained in more detail below with the help of Figures 5 and 6. Figure 4 shows the plug part 4 alone without heating section 2. According to it, retention arms 28, 30 arranged on both sides of the heating section (figure 3) extend from the plug flange 10 moving downwards, which in practice form front walls of the heating section 2. These arms of retention 28, 30 are in turn made with a profile 32, which allows a fixation in place in the housing of the component to be heated. The plug part 4 of the heater 1 is preferably manufactured by the plastic injection molding process. On the side faces oriented towards each other of the retention arms 28, 30 in each case an interlocking shoulder 33, 35 is made, through which the heating section 2 between the retention arms can be fixed in place . The locking projections 33, 35 absorb the force (activation force) that occurs when the activation pin 20 is inserted into the heating insert according to figures 5 and 6.

Figure 5 shows a representation of the heater 1 with the plug part 4 removed. The U-shaped insulating sheet 6, whose open lateral areas are covered by the retaining arms 28, 30, is clearly recognized.

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described above, not visible in figure 5. In this representation both power supply lines 14, 16 and the activation pin 20 are also recognized with their activation projection 18. In this, the notch 26 described above is configured in the that the spring tongues 22, 24 (not visible) with spring elasticity are engaged, this coupling can be nullified with spring elasticity relatively easily.

The heating section 2 of the heater 1 is configured in this case with four heating elements PTC 34a, 34b and 36a, 36b, which can be seen well in the view according to figure 6, which shows the heater 1 shown without plug part 4 in a view rotated approximately 90 ° with respect to Figure 5. According to it, in each case two heating elements PTC 34a, 34b and 36a, 36b are placed facing two to two, the major areas of these resistance elements running PTC parallel to the major areas of the insulating sheet 6. In the space between the PTC resistor elements 34a, 34b and 36a, 36b a first contact element 38, configured approximately U-shaped, is inserted from the power line of current 16, whose structure can be deduced especially well from figure 6 and from the individual representation according to figure 8. According to it, this first contact element 38 has two electrode plates 40, 42, qu e are in each case adjacent to one of the pairs of resistance elements PTC 34a, 34b, or 36a, 36b and whose base area corresponds approximately to that of the associated resistance element pair. Both electrode plates 40, 42 are joined on the front side in each case by a base part 44a, 44b. Each of these base parts 44a, 44b is made with a concave bulge 46a, 46b, so that both electrode plates 40, 42 can move with spring elasticity by elastic deformation of the base parts 44a, 44b and the concave bulges 46a, 46b associated and in parallel with respect to each other. According to figure 5, in the lateral edges of the electrode plates 40, 42, interlocking notches 47, 49 are configured for interlocking with the interlocking projections 33, 35. In addition to the interlocking, the notches 47, 49 also absorb the force of activation.

According to the representations in Figures 5, 6 and 8, the contact tongue 48 is connected through a contact arm 50 curved approximately U-shaped with the electrode plate 40.

In both electrode plates 40, 42 of the power supply line 16, a spring element 52, 54 is retained in each case (see Figures 6 and 7). In the exemplary embodiment shown, for fixing in place these spring elements 52, 54 on each electrode plate 40, 42, two clamping tabs 56a, 56b or 58a, 58b are made (see Figure 8), which in each case they surround laterally an upper crossbar 60, 62 of the respective spring element 52, 54. Both spring elements 48, 50 also have, according to the individual representation in figure 9 and figures 6 and 7, lower cross bars 64 , 66 which run parallel to the upper crossbars 60, 62 and between which two spring bridges 68a, 68b or 70a, 70b are spaced apart from each other. In the representations according to figures 6 and 7, in each case only the spring bridges 68a, 70a located in the direction of observation can be seen, while the corresponding spring bridges 68b or 70b are covered in the view according to figure 7 by the spring bridges 68a or 70a and are not visible in the view according to figure 6. On the narrow side edges of the upper crossbars 60, 62, two recesses 61a, 61b are configured in each case, which in the assembled state are surrounded by clamping tabs 56a, 56b; 58a, 58b, for mechanically joining the spring elements 52, 54 with the corresponding power supply lines 14, 16.

Each spring element 52, 54 is therefore supported with its upper and lower crossbars 60, 64 or 62, 66 on the corresponding electrode plate 40, 42, producing a fixation at its lateral site through the clamping tabs 56a , 56b or 58a, 58b configured on each electrode plate 40, 42. Both apices 72, 74 (figure 7) of the spring bridges 68, 70 are at a relatively short distance from each other. As can be deduced in particular from the representation according to Figure 7, in this state of assembly of the heater 1 both electrode plates 42, 40 are somewhat spaced from the resistance elements PTC 34b, 36b, so that in each case there is an interstitium s, which allows the PTC heating elements 34, 36 to be inserted practically without force and therefore carefully. According to the representation in Figure 7, an activation section 76 of the activation pin 20 is inserted in the area between the spring bridges 68, 70 facing each other, but without being in physical contact with the spring elements 52, 54 in the mounting position or release position (see figure 7).

By inserting the activation pin 20 between the spring elements 52, 54, the cross bars 60, 62 are fixed in place, due to their union established by means of the clamping tabs 56a, 56b; 58a, 58b, with respect to electrode plates 40, 42. The cross bars 64, 66 in the spring elements 52, 54 are pushed when the activation pin 20 is inserted, so they do not retain their position.

According to the individual representation of the activation pin 20 in Figure 10, it has an approximately fork-shaped structure, the projection 18 projecting upwardly with the notch 26 and another opening 78 (seen according to Figure 10) from a link portion 80 positioned slightly with respect to the plane of the activation section 76, from which two arms 82, 84 extend, which together form the activation section 76. These arms have a retracted end section 86, 88 , which is curved backwards, by a curvature procedure, in the plane of the part of the incorporation side of the arms 82,

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84, then the front face areas 90, 92 being at the end side curved in turn slightly out of this plane. By bending out the front face areas 90, 92, an assurance is possible in case of failure of the spring tabs 22, 24. If these do not interlock the activation pin, it can only move up to the height of the spring elements. This avoids an electrical short circuit, which could occur in case of contact of the activation plug 20 with the power supply line 14. The activation plug 20 is guided, through appropriate guides, so that it can move in the plug part 4 (vertically in figure 6).

Figure 11 shows an individual representation of the second power supply line 14, which has a structure analogous to the power supply line 16 explained with the aid of Figure 8 and which according to the representations in Figures 5 and 6 is interspersed with the same. The power supply line 14 has two electrode plates 94, 96 with approximately the same base area as electrode plates 40, 42. Both electrode plates 94, 96 are joined together with spring elasticity again through of base parts 98a, 98b, linked on the front side, with in each case a concave bulge 100a, 100b. As can be deduced in particular from Figure 6, the electrode plates 94, 96 and the base parts 98a, 98b are located outside the corresponding construction elements of the power supply line 16, the elements of which are arranged PTC resistor 34a, 34b between electrode plates 42 and 96 and PTC resistor elements 36a, 36b between electrode plates 40 and 94 (see Figure 7). A contact tongue 102 is linked through a U-shaped part 104 with the electrode plate 94. Both current supply lines 14, 16 are configured as curved die-cut pieces. According to Figure 11, a fixing element 110 is configured on the electrode plate 96, which can be clearly seen in the illustration according to Figure 5. During assembly, this fixing element 110 is engaged in a corresponding recess of the part of plug 4, to set the heating section 2.

Figure 12 shows a heater 1 inserted in a housing or in a cavity of a container to be heated, the heating section 2 being housed flush in the cavity 106 and the plug part 4 being seated with the plug flange 10 on an outer face 108. In this regard, the insulating sheet 6 sits on the entire surface against the perimeter walls of the cavity 106, although the front face of the heating section 2 may be distanced from a bottom of the cavity. As already explained, for insertion in the cavity 106, the activation pin 20 is left in its position shown in Figure 7, in which the electrode plates 40, 42 and 94, 96 are not brought into contact. with resistance elements PTC 34, 36 with pretension. Furthermore, correspondingly in the mounting position according to Figure 7, the insulating sheet 6 is not pressed against the wall of the cavity 106.

As explained, in the mounting state the gap between the electrode plates 40, 42 located inside and the resistance elements PTC 34a, 34b is present; 36a, 36b associated in each case. After insertion of the heater 1 in the housing 106, practically without force due to the predefined play, the activation pin 20 is pushed, either by the plug applied or by an appropriate tool, through the activation projection 18 which is enters the plug space 12, downwards from the representation according to figure 6 (figure 12), so that both folded end sections 86, 88 in each case come into contact with the associated spring bridges 52, 54, which they run parallel to them and deform them, in such a way that a pretension force is applied on the associated electrode plates 40, 42 and these are prestressed over the entire surface and with a relatively high pretension force against the resistance elements PTC 34a, 34b, 36a, 36b adjacent, so that the gap is closed. Through this spring force the electrode plates 94, 96 located outside are also pressed, with the insulating sheet 6 surrounding them, all over the surface against the wall of the component housing, so that a transfer of optimal heat

In the representation according to figure 12 it is clearly recognized that in the activation position shown the spring tabs 22, 24 (in figure 12 only the spring tongue 24 is visible) of the plug part 4 fit the notch 26, so that the activation pin 20 is fixed in place in its vertical position (figure 12). In the mounting position (figure 6) the spring tabs 22, 24 with their locking projections are inserted into the opening 78 of the activation pin 20, which has a somewhat larger area. In this way the activation pin 20 is preset in the mounting position. The force F is sufficient to overcome the engagement of the projections of the spring tongues 22, 24 with the notch 78.

If the component housing is made of metallic material, the insulating sheet 6 serves as electrical insulation. Likewise, the insulating sheet can also serve as compensation for slight irregularities in the component housing.

A particular advantage of this construction is that manufacturing tolerances that are eventually present and temperature-determined measurement oscillations can be compensated by the considerable spring force of the spring bridges 74a, 74b, so that a mechanical, thermal contact is always guaranteed. and electric enough. Furthermore, the assembly of the heater 1 itself and its insertion in the housing are facilitated by means of the set s.

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In principle, this design can be simplified even more, if the activation projection 18 of the activation plug 20 acts as a power supply line, so that the current supply is only possible if the activation pin 20 is moved to its activation position.

The constructive principle that forms the basis of the invention can be easily adapted to various sizes and yields.

An electric heater with at least one heating element is disclosed, which can be brought into thermal contact with a wall of a component to be heated. This heating section is provided with an activation pin, which can be moved from a release position to an activation position, to move the heating element, after its insertion in the housing, to an active position, in which it is guaranteed a sufficient thermal and / or electrical contact.

List of reference numbers

 one

 Heater

 2

 heating section

 4

 plug part

 6

 insulating sheet

 8

 plug outline

 10

 plug flange

 12

 plug space

 14

 power supply line

 16

 power supply line

 18

 outgoing activation

 twenty

 activation pin

 22

 spring tongue

 24

 spring tongue

 26

 notch

 28

 retention arm

 30

 retention arm

 32

 profile

 33

 interlocking highlight

 3. 4

 PTC resistance element

 35

 interlocking highlight

 36

 PTC resistance element

 38

 contact element

 40

 electrode plate

 42

 electrode plate

 44

 base part

 46

 concave bulge

 47

 interlocking notch

 48

 contact tab

 49

 interlocking notch

 fifty

 contact arm

 52

 spring element

 54

 spring element

 56

 tightening flange

 58

 tightening flange

 60

 upper crossbar

 61

 recess

 62

 upper crossbar

 64

 lower crossbar

 66

 lower crossbar

 68

 spring bridge

 70

 spring bridge

 72

 apex

 74

 apex

 76

 activation section

 78

 opening

 80

 link part

 82

 arm

 84

 arm

 86

 folded end section

 88

 folded end section

 90

 front face area

92

94

96

98

100

102

104

106

108

110

front face area electrode plate electrode plate base part bulging concave contact tongue U part cavity face

fixing element

Claims (14)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 1. Electric heater, which is inserted with a heating section (2) in a housing of a component to be regulated thermostatically, with heating elements (34, 36) supplied with current through power supply lines (14 , 16), which can be placed directly or indirectly in thermal contact with a wall of the housing, characterized by an activation pin (20), which can be moved from a release position to an activation position, to move the heating elements ( 34, 36) from a mounting position, in which they are not or are only in small measure in thermal contact with the wall or in electrical contact with the power supply lines (14, 16) associated, to an active position, in which the thermal contact and / or the electrical contact is guaranteed, the heater having at least two heating elements (34, 36) facing each other, to which an element is associated in each case spring (52, 54), putting the activation pin (20) in its activation position between both spring elements (42, 44), to request the heating elements with an elastic pretension in the direction of the wall or in the Sense of a contact. 2. Heater according to claim 1, wherein the activation pin (20) has a cantilever activation projection (18) and an activation section (76) on the side of the heating element, which for activation is set in active connection with one of the heating elements (34, 36). 3. Heater according to claim 2, wherein the power supply lines (14, 16) enter a plug space (12) of a plug part (4), in which the projection of activation (18) of the activation pin (20). 4. Heater according to one of the preceding claims, wherein at least one of the power supply lines (14, 16) is associated with a spring element (52, 54), which in the active position of the power plug activation (20) requests one of the heating elements in the direction of the wall or in the direction of an electrical contact. 5. Heater according to claim 4, wherein the spring element (52, 54) is attached to the power supply line (14, 16). 6. Heater according to claim 5, wherein the spring element (52, 54) is fastened through tightening flanges (56, 58). 7. Heater according to claims 4 or 5, wherein the power supply lines (14, 16) are configured with spring elasticity. 8. Heater according to claim 7, wherein each power supply line (14, 16) has an approximately U-shaped structure, being configured, to provide the spring effect, on a base part (44, 98 ) in each case a concave bulge (46, 100). 9. Heater according to claim 7, wherein both power supply lines (14, 16) are made with spring elasticity. 10. Heater according to one of claims 1 to 9, wherein four heating elements (34a, 34b; 36a, 36b) are provided, facing each other two to two and between which the spring elements (52, 54), to which an activation pin (20) is associated together. 11. Heater according to one of the preceding claims, wherein the activation pin (20) is configured as a curved die-cut piece with two folded end sections (86, 88) that form the activation section (76). 12. Heater according to one of the preceding claims, wherein in the activation position the activation pin (20) is fixed in place with force or shape drag. 13. Heater according to one of the preceding claims, wherein the heating elements are PTC resistance elements (34, 36). 14. Heater according to one of the preceding claims, wherein the heating section (2) has an insulating sheet (6) in the area adjacent to the wall.