EP2429257A1 - Electric heater - Google Patents

Abstract

The heater (1) has positive temperature coefficient resistor elements (34, 36) supplied with current over power supplies and directly or indirectly brought in thermal contact with a wall of a retainer. An activation pin is adjustable from a release position into an activation position. The resistor elements are adjustable from an assembly position into an effective position in which thermal and/or electrical contacts are ensured. The resistor elements are in thermal contact with the wall or in electrical contact with the power supplies in the assembly position.

Description

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

Such electric heaters can be used, for example, in the blow-by system of internal combustion engines or for heating a tank of an SCR system (Selective Catalytic Reduction). On the homepage of the applicant ( www.dbk-group.de ) examples of such electrical heaters are shown. Accordingly, these have a heating section which is inserted into a correspondingly shaped receptacle of the component to be thermostated, for example a tank or a flow path of the blow-by gas. This heating section goes into a plug or contacting part, in which the power supply lines for the heater are arranged. In the known heaters, resistance elements, for example PTC heating elements are used, which are energized via the power supply lines of the contacting and as possible abut against a wall portion of the housing portion, so that the heat transmitted directly through the wall of the heating section and the adjacent wall of the component to be thermostated becomes. It is important that on the one hand to improve the heat transfer, a large heat exchange surface is present and further no insulating air gaps are arranged in the heat transfer path.

The problem is that it may come to an insulating air gap in the area of the system of the heating element to the wall due to tolerances in the production and temperature fluctuations in the operation of the heater or the component to be heated. This disadvantage can only be ruled out if the fits for the heating elements supporting areas are very narrow, but then the installation of the heater due to the required tight fitting dimensions is relatively difficult, so that especially in the use of PTC devices the risk of Damage to the heating element is.

In the EP 1375997 discloses a solution in which a heating section is biased against a surface of the component to be heated, so that the heat transfer takes place in the region of the one-sided installation of the heating section. Such a solution has the disadvantage that the heat exchange surface and thus the possible heat input into the component due to the low power density is low.

In contrast, the invention has for its object to provide an electric heater, in which an optimal heat transfer is ensured with simple installation.

This object is achieved by an electric heater with the features of claim 1.

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

The electric heater according to the invention has a heating section which can be inserted into a receptacle of a component to be thermostated. The heater also has heating elements powered by power supply. According to the invention, the heater is designed with an activation pin, which is adjustable from a release position into an activation position. In the release position, the heating element is in a play-loaded mounting position in which the heating element is not or only slightly in thermal contact with the wall or in electrical contact with the power supply lines. By moving the activation pin in the activation position, the heating element or the power supply is adjusted to an operative position in which the thermal and / or electrical contact is formed substantially free of play and area.

With the solution according to the invention thus a heater is provided in which the heating elements are initially arranged in a game-afflicted, not in a compact system on the wall to be heated or the power supply lines. To activate the heater then the activation pin is adjusted, so that the heating elements are adjusted or moved into their operative position. In this way, the assembly of the Heater much easier, since the heating elements are initially taken up with relatively large game in the housing. In the activation position of the activation pin this game is then canceled, so that the desired thermal and electrical contact is made with very good heat transfer.

The thermal and / or electrical contacting produced by virtue of the displacement of the activation pin is preferably accompanied by mechanical contacting, which ensures that the heating elements are pressed against the corresponding wall of the receptacle of the component. The Applicant reserves the right to claim this mechanical contact additionally or independently of the thermal and electrical contact. In this case, the mechanical contacting of the heating elements indirectly, i. via intermediate components or directly.

In a preferred embodiment of the invention, the activation pin has an actuating projection projecting from a housing section and a heater-element-side activation section which comes into operative connection with the heating element for activating the heater by adjusting the actuating projection, wherein the activation pin can abut directly or indirectly on the heating element.

It is also advantageous that in the release position of the activation pin, an electrical mating connector is not pluggable. Thus, a simple hedge against misuse is realized.

The structure of the heater is particularly simple if at least one of the power supply lines is formed with a spring element which, in the active position of the activation pin, acts on the heating element in the direction of the wall.

In a variant of the invention, a spring element is attached to a power supply. This can be maintained, for example, via Crimplaschen the power supply.

In one embodiment of the invention, at least one of the power supply lines is resilient, so that by the spring action tolerance deviations can be compensated and a flat contact of the heating element is ensured in its operative position.

The power supply can have an approximately U-shaped construction, wherein on a U-base, a spring effect providing concavity is formed.

According to the invention it is preferred if both power supply lines are resilient and / or formed with spring elements, via which, for example, at least one heating element in the direction of its operative position can be acted upon.

In one embodiment of the invention, the heater has at least two opposing heating elements, each associated with a spring element in the sense of the foregoing, wherein the activation pin dips in its activation position between the two spring elements to bias the heating elements by the spring force in the direction of the wall , In this variant, two heating elements are thus pressed against mutually opposite walls of the receptacle of the component to be heated, so that a significantly improved heat input with high power density can be realized due to the improved heat transfer surface compared to the cited in the introduction of the prior art.

A variant of the invention provides that a total of four heating elements are provided which face each other in pairs and between which spring elements and an activation pin is arranged.

The activation pin can be made of metal as a stamped and bent part with a folded activation section or made of plastic.

In a further development of the invention, the activation pin is fixed in position in its activation position by frictional or positive engagement with a further component of the heater, for example, the aforementioned plug part. This fixation can be done, for example, by latching, in which a tongue snaps into a recess of the activation pin or in kinematic reversal, a projection of the activation pins in a recess of the plug part or other housing-fixed portion of the heater.

According to the invention it is preferred if the electrical heater is designed with PTC resistor elements.

An advantage of the described embodiment also that the heater is removable again. After deactivation of the activation pin, the heater is again powerless removable and can be replaced, for example, in case of service. However, it is important to ensure that the heater is not removed arbitrarily. It makes sense to use a special tool here.

• Figur 1 eine dreidimensionale Ansicht eines erfindungsgemäßen elektrischen Heizers;
• Figur 2 eine Ansicht von Oben auf einen Heizer gemäß Figur 1;
• Figur 3 den Heizer aus Figur 1 ohne Isolierfolie;
• Figur 4 ein Steckerteil des Heizers aus Figur 1;
• Figur 5 eine dreidimensionale Ansicht des Heizers gemäß Figur 1 ohne Gehäuse;
• Figur 6 die Anordnung gemäß Figur 5 in einer anderen Ansicht;
• Figur 7 eine Seitenansicht des Heizers aus Figur 1 ohne Gehäuse;
• Figur 8 eine Einzeldarstellung einer ersten Stromzuführung des Heizers gemäß Figur 1;
• Figur 9 eine Einzeldarstellung eines Federelementes des Heizers aus Figur 1;
• Figur 10 eine Einzeldarstellung eines Aktivierungspins des Heizers aus Figur 1;
• Figur 11 eine Einzeldarstellung einer zweiten Stromzuführung des Heizers aus Figur 1 und
• Figur 12 den Heizer aus Figur 1 in eine Tasche eingesetzt.

A preferred embodiment of the invention will be explained in more detail below with reference to schematic drawings. Show it:

• FIG. 1 a three-dimensional view of an electric heater according to the invention;
• FIG. 2 a view from the top on a heater according to FIG. 1 ;
• FIG. 3 the heater off FIG. 1 without insulating film;
• FIG. 4 a plug part of the heater off FIG. 1 ;
• FIG. 5 a three-dimensional view of the heater according to FIG. 1 without housing;
• FIG. 6 the arrangement according to FIG. 5 in another view;
• FIG. 7 a side view of the heater off FIG. 1 without housing;
• FIG. 8 a detailed representation of a first power supply of the heater according to FIG. 1 ;
• FIG. 9 an individual representation of a spring element of the heater off FIG. 1 ;
• FIG. 10 a single representation of an activation pin of the heater off FIG. 1 ;
• FIG. 11 a single representation of a second power supply of the heater off FIG. 1 and
• FIG. 12 the heater off FIG. 1 inserted in a bag.

FIG. 1 shows a view of a heater 1, which consists in principle of a heating section 2 and a plug part 4. As explained in more detail below, the power supply lines for contacting the heater 1 are arranged in this plug part 4. The heating section 2 is inserted into a receptacle or pocket of a component to be heated, for example an SCR tank, the heating section 2 lying flat against the wall of this receptacle so that a good heat transfer is ensured. In the illustrated embodiment, a non-electrically insulating insulating film 6 which optimizes the heat transfer is provided in the abutment region on the receptacle, not shown, on the heating section 2, which will be described in more detail later. In the region of the plug part 4, a plug contour is attached, to which a correspondingly profiled plug connection of the power supply is applied, this plug contour 8 being designed so that a correct position mounting is ensured.

FIG. 2 shows a plan view of the plug part 4 FIG. 1 , It can be seen a plug flange 10, in accordance with the view FIG. 2 covers the heating section 2 and also acts as insertion limit for this. The profiled plug part 4 engages with a peripheral wall a plug space 12, in which the above-mentioned plug of the power supply is at least partially immersed. At the bottom of this plug space 12 can be seen two projecting into this tongue-shaped power supply lines 14, 16 of the heating section 2 and also in this plug space 12 hineing protruding actuating projection 18 of an activation pin 20. This actuating projection 18 is supported on two spring tongues 22, 24 of the plug part 4 and extends through the bottom of the plug space 12 into the heating section 2. The spring tongues 22, 24 each have a locking projection which dips into recesses 26, 78 of the activation pin 20. In the release position of the activation pins 20, the spring tongues 22, 24 engage in the recess 78 of the activation pin 20, this is thus fixed in position against accidental displacement. If one acts on the actuating projection 18 in the illustration according to FIG. 2 From the viewer forth with a thrust, so the resilient engagement of the spring tongues 22, 24 is released, so that the activation pin 20 can be moved in the direction of the heating section 2. In the operative position, the Spring tongues 22, 24 then into the recess 26 of the activation pin and lock it. This feature is explained in detail below.

FIG. 3 shows the heater 1 according to FIG. 1 With removed insulating film 6. As a result, the actual heating section 2 is visible, the below with reference to FIGS. 5 and 6 is explained in more detail. FIG. 4 shows the plug part 4 alone without heating section 2. Accordingly, extending from the plug flange 10 down on both sides of the heating section ( Fig. 3 ) arranged holding legs 28, 30, which form practically end walls of the heating section 2. These holding legs 28, 30 are in turn designed with a profile 32, which allows a positional fixation in the recording of the component to be heated. The plug part 4 of the heater 1 is preferably made by injection molding of plastic. At the mutually facing side surfaces of the holding legs 28, 30 each have a latching nose 33, 35 executed, via which the heating section 2 can be fixed in position between the retaining legs. The latching lugs 33, 35 take the force (activating force) resulting from the insertion of the activation pin 20 onto the heating insert FIGS. 5 and 6 on.

FIG. 5 shows a representation of the heater 1 with removed connector part 4. It can be clearly seen the U-shaped insulating film 6, the open side areas by the above, in FIG. 5 not visible retaining legs 28, 30 are covered. In this illustration, one recognizes the two power supply lines 14, 16 and the activation pin 20 with its actuating projection 18. In this the above-described recess 26 is formed, in which the (non-visible) spring tongues 22, 24 resiliently engage, said resilient engagement relatively easily can be canceled.

The heating section 2 of the heater 1 is formed in this case with four PTC heating elements 34a, 34b and 36a, 36b, in the view according to FIG FIG. 6 are clearly visible that the heater 1 shown without plug part 4 in a view rotated by about 90 ° FIG. 5 shows. Accordingly, in each case two PTC heating elements 34a, 34b and 36a, 36b face each other in pairs, the large areas of these PTC resistance elements extending parallel to the large areas of the insulating film 6. The space between the PTC resistance elements 34a, 34b and 36a, 36b is immersed approximately U-shaped trained first contact element 38 of the power supply 16 a, whose structure is particularly good FIG. 6 and the individual presentation according to FIG. 8 is removable. Accordingly, this first contact element 38 has two electrode plates 40, 42, each of which bears against one of the PTC resistor element pairs 34a, 34b or 36a, 36b and whose base area approximately corresponds to that of the associated resistor element pair. The two electrode plates 40, 42 are each connected to the front side by a base part 44a, 44b. Each of these base parts 44a, 44b is designed with an indentation 46a, 46b, so that the two electrode plates 40, 42 are elastically and parallel movable by elastic deformation of the base parts 44a, 44b and the associated indentations 46a, 46b. According to FIG. 5 are on the side edges of the electrode plates 40, 42 locking recesses 47, 49 for locking with the locking lugs 33, 35 are formed. In addition to the latching of the recesses 47, 49 and the activation force is added.

According to the representations in the FIGS. 5, 6 and 8th the contact tongue 48 is connected to the electrode plate 40 via an approximately U-shaped bent contact leg 50.

At the two electrode plates 40, 42 of the power supply 16 is in each case a spring element 52, 54 (see FIGS. 6 and 7 ) held. In the illustrated embodiment, two Crimplaschen 56a, 56b and 58a, 58b (see FIG. 8 ), each of which laterally surround an upper transverse strut 60, 62 of the respective spring element 52, 54. The two spring elements 48, 50 further have according to the individual representation in FIG. 9 and the FIGS. 6 and 7 lower transverse struts 64, 66 which extend parallel to the upper transverse struts 60, 62 and between which two mutually spaced spring bridges 68a, 68b and 70a, 70b arch each other. In the representations according to the FIGS. 6 and 7 In each case, only the spring bridges 68a, 70a lying in the direction of viewing are visible, and the associated spring bridges 68b and 70b are in the view according to FIG FIG. 7 covered by the spring bridges 68a and 70a and in the view according to FIG. 6 not visible. At the lateral narrow edges of the upper transverse struts 60, 62 are each two recesses 61 a, 61 b formed in the mounted state of the Crimplaschen 56a, 56b; 58a, 58b are encompassed in order to connect the spring elements 52, 54 with the corresponding power supply lines 14, 16 mechanically.

Each spring element 52, 54 is thus supported with its upper and lower transverse struts 60, 64 and 62, 66 on the associated electrode plate 40, 42, wherein a lateral position fixing on the formed on each electrode plate 40, 42 Crimplaschen 56 a, 56 b and 58a, 58b takes place. The two vertices 72, 74 ( FIG. 7 ) of the spring bridges 68, 70 are at a comparatively small distance from one another. As in particular from the illustration according to FIG. 7 can be removed, stand in this mounting state of the heater 1, the two electrode plates 42, 40 slightly spaced from the PTC resistor elements 34b, 36b, so that in each case a gap s remains, which allows the PTC heating elements 34, 36 virtually powerless and thus to use gently. As shown in FIG. 7 an activation section 76 of the activation pin 20 dips into the area between the opposing spring bridges 68, 70 and is in the mounting position or release position (see FIG. 7 ) but not in touching contact with the spring elements 52, 54.

When inserting the activation pin 20 between the spring elements 52, 54 remain the cross struts 60, 62 by their means of the Crimplaschen 56 a, 56 b; 58a, 58b made fixed in position to the electrode plates 40, 42. The transverse struts 64, 66 on the spring elements 52, 54 are displaced upon insertion of the activation pin 20, so do not retain their position.

According to the detailed representation of the activation pin 20 in FIG FIG. 10 this has an approximately fork-shaped structure, wherein the actuating projection 18 with the recess 26 and a further opening 78 upwards (view FIG. 10 ) protrudes from a slightly raised to the level of the activation section 76 connection 80 from which two legs 82, 84 extend, which together form the activation section 76. These legs have a folded end portion 86, 88, which is bent back by a bending operation on the plane of the attachment-side part of the legs 82, 84, in which case the end-side end face regions 90, 92 are again slightly bent out of this plane. By bending out the end face regions 90, 92 is a fuse in case of failure of Spring tongue 22, 24 possible. If this does not lock the activation pin, it can only be moved up to the height of the spring elements. As a result, an electrical short circuit, which could arise upon contact of the activation pin 20 with the power supply 14, prevented. The activation pin 20 is displaceable via suitable guides in the plug part 4 (vertically in FIG. 6 ) guided.

FIG. 11 shows a single representation of the second power supply 14, which has a similar structure as that based FIG. 8 explained power supply 16 has and according to the representations in the FIGS. 5 and 6 is nested with this. The power supply 14 has two electrode plates 94, 96 with approximately the same base area as the electrode plates 40, 42. Both electrode plates 94, 96 are in turn connected to one another via frontally connected base parts 98a, 98b, each with a concavity 100a, 100b. In particular FIG. 6 can be removed, the electrode plates 94, 96 and the base parts 98a, 98b outside of the corresponding components of the power supply 16, wherein the PTC resistor elements 34a, 34b between the electrode plates 42 and 96 and the PTC resistor elements 36a, 36b between the electrode plates 40 and 94 are arranged (see FIG. 7 ). A contact tongue 102 is connected to the electrode plate 94 via a U-part 104. Both power supply lines 14, 16 are formed as stamped and bent parts. According to FIG. 11 is formed on the electrode plate 96, a fixing element 110, the more clearly in the figure FIG. 5 is visible. During assembly, this fixing element 110 engages in a corresponding recess of the plug part 4 in order to fix the heating section 2.

FIG. 12 shows a heater 1 used in a receptacle or pocket of a container to be heated, wherein the heating section 2 is received flush in the pocket 106 and the plug member 4 is seated with the plug flange 10 on an outer surface 108. In this case, the insulating sheet 6 sits flat against the peripheral walls of the pocket 106, wherein, however, the end face of the heating section 2 may be spaced to a bottom of the bag. As already explained, to insert the pocket 106, the activation pin 20 in its in FIG. 7 leave shown position in which the electrode plates 40, 42 and 94, 96 are not contacted with the PTC resistor elements 34, 36 with bias. Furthermore is also according to the mounting position according to FIG. 7 the insulating film 6 is not pressed against the wall of the pocket 106.

As explained, in the assembled state, the gap s between the inner electrode plates 40, 42 and the respectively associated PTC resistor elements 34a, 34b; 36a, 36b available. After by the given game s almost powerless insertion of the heater 1 in the receptacle 106 is activated either by the attached plug or by a suitable tool, the activation pin 20 via the projecting into the plug space 12 actuating projection 18 from the illustration FIG. 6 moved down ( Fig. 12 ), so that the two folded end portions 86, 88 in each case come into contact with the associated, parallel spring bridge 52, 54 and deform them such that a biasing force is applied to the associated electrode plates 40, 42 and this area and with comparatively high Biasing force against the adjacent PTC resistor elements 34a, 34b, 36a, 36b are biased so that the gap s closes. About this spring force and the outer electrode plates 94, 96 are pressed with the surrounding this insulating 6 flat against the wall of the recording of the component, so that an optimal heat transfer is ensured.

In the illustration according to FIG. 12 it can be seen clearly that in the illustrated activation position the spring tongues 22, 24 (in FIG. 12 only the spring tongue 24 visible) of the plug part 4 in the recess 26 snap, so that the activation pin 20 in its vertical position ( FIG. 12 ) is fixed in position. In the mounting position ( FIG. 6 ) plunge the spring tongues 22, 24 with their locking projections in the opening 78 of the activation pin 20, which has a slightly larger area. As a result, the activation pin 20 is pre-fixed in the mounting position. The force F is sufficient to overcome the engagement of the projections of the spring tongues 22, 24 with the recess 78.

If the recording of the component made of metallic material, the insulating film 6 serves as electrical insulation. In addition, the insulating film can also be used as a compensation for slight bumps in the recording of the component.

A particular advantage of this design is that any existing manufacturing tolerances and temperature-related dimensional variations can be compensated by the considerable spring force of the spring bridges 74a, 74b, so that a sufficient mechanical, thermal and electrical contact is always ensured. In addition, the assembly of the heater 1 itself and its insertion into the receptacle is facilitated by the game s.

In principle, this concept can be further simplified if the actuating projection 18 of the activation pin 20 acts as a power supply, so that then the energization is only possible when adjusting the activation pin 20 in its activation position.

The construction principle underlying the invention can be easily adapted to different sizes and benefits.

Disclosed is an electrical heater with at least one heating element, 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 is adjustable from a release position to an activation position to adjust the heating element after insertion into the receptacle in an operative position in which a sufficient thermal and / or electrical contact is ensured.

LIST OF REFERENCE NUMBERS

1

stoker

2

heating section

4

plug part

6

insulation

8th

plug contour

10

connector flange

12

plug compartment

14

power supply

16

power supply

18

operating projection

20

enable pin

22

spring tongue

24

spring tongue

26

recess

28

holding leg

30

holding leg

32

profile

33

locking lug

34

PTC resistive element

35

locking lug

36

PTC resistive element

38

contact element

40

electrode plate

42

electrode plate

44

base

46

concavity

47

recess

48

contact tongue

49

recess

50

contact legs

52

spring element

54

spring element

56

Crimplasche

58

Crimplasche

60

upper cross strut

61

recess

62

upper cross strut

64

lower crossbar

66

lower crossbar

68

spring bridge

70

spring bridge

72

vertex

74

vertex

76

activating section

78

breakthrough

80

connection

82

leg

84

leg

86

folded end section

88

folded end section

90

End face region

92

End face region

94

electrode plate

96

electrode plate

98

base

100

concavity

102

contact tongue

104

U-part

106

bag

108

area

110

fixing

Claims (15)

Electric heater which can be used with a heating section (2) in a receptacle of a component to be thermostated, with heating elements (34, 36) energized via power supply lines (14, 16) which can be brought directly or indirectly into thermal contact with a wall of the receptacle characterized by an activation pin (20) which is adjustable from a release position to an activation position to the heating elements 34, 36 from a mounting position in which they are not or only to a reduced extent in thermal contact with the wall or in electrical contact with the associated power supply lines (14, 16) are adjustable in an operative position, in which the thermal contact and / or electrical contact is ensured. A heater according to claim 1, wherein the activating pin (20) has a cantilevered actuating projection (18) and a heater-element-side activating portion (76) which engages the heating element (34, 36) for activation. Heater according to claim 2, wherein the power supply lines (14, 16) protrude into a plug space (12) of a plug part (4) into which the actuating projection (18) of the activation pin (20) protrudes. Heater according to one of the preceding claims, wherein at least one of the power supply lines (14, 16) is assigned a spring element (52, 54) which acts in the active position of the activation pin (20) the heating element in the direction of the wall or in the sense of an electrical contact. Heater according to claim 4, wherein the spring element (52, 54) is fixed to the power supply (14, 16). Heater according to claim 5, wherein the spring element (52, 54) via Crimplaschen (56, 58) is held. Heater according to claim 4 or 5, wherein the power supply lines (14, 16) are resilient. A heater according to claim 7, wherein each power supply (14, 16) has an approximately U-shaped structure, wherein for providing the spring action on a base part (44, 98) each have a concavity (46, 100) is formed. Heater according to claim 7, wherein both power supply lines (14, 16) are resilient. Heater according to one of the preceding claims, wherein it has at least two mutually opposite heating elements (34, 36), each associated with a spring element (52, 54), wherein the activation pin (20) in its activation position between the two spring elements (42, 44 ) dips to apply the heating elements with a spring bias in the direction of the wall or in the sense of contacting. Heater according to one of the claims related to claim 10 or according to claim 10, wherein four heating elements (34a, 34b, 36a, 36b) are provided which face each other in pairs and between which the spring elements (52, 54) are arranged, which together have an activation pin (20) is assigned. A heater as claimed in any one of the preceding claims, wherein the activating pin (20) is a stamped and bent part having two folded end portions (86, 88) forming the activating portion (76). Heater according to one of the preceding claims, wherein the activation pin (20) in the activation position non-positively or positively fixed in position. A heater according to any one of the preceding claims, wherein the heating elements are PTC resistance elements (34, 36). Heater according to one of the preceding claims, wherein the heating section (2) in the contact area to the wall has an insulating film (6).

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