EP3723448A1 - Heating device - Google Patents

Abstract

A heating device is described with a ceramic heating resistor (2), a contact plate (3, 4) on which the heating resistor (2) rests, an insulation layer (5) that covers a side of the contact plate (4) facing away from the heating resistor (2). covered, wherein the heating resistor (2), the contact plate (3, 4) and the insulation layer (5) form a stack, a receiving part (1) in which the stack is arranged, and a spring clip (6), which the stack with a pressing force (F) presses against the receiving part (1), the receiving part (1) forming an abutment on which a first end (6a) of the spring clip (6) is supported. According to the invention, it is provided that the abutment is designed in such a way that it allows a pivoting movement of the spring clip (6) around its first end (6a) during assembly of the spring clip (6) in order to bring the spring clip (6) into its working position which he applies the contact pressure (F) to the stack.

Description

The invention is based on a heating device with the features specified in the preamble of claim 1, as for example from the DE 10 2017 209 568 A1 is known.

Such heating devices contain one or more ceramic heating resistors and at least one contact plate which makes electrical contact with the heating resistor or the heating resistors. A second contact plate or a receiving part in which the heating resistor or the heating resistors and contact plate (s) are arranged can serve as the ground contact. The receiving part is part of a housing of a pump, delivery module or other device that is heated with the heating device.

Contact plate (s), heating resistor or heating resistors and an insulation layer form a stack that is pressed against the receiving part by a spring clip and thus ensures good thermal contact between the receiving part and the stack cares. In the case of the DE 10 2017 209 568 A1 known heating device, the bracket has an approximately U-shaped cross-section, so that a central part of the bracket running parallel to the contact plate rests against the stack. For assembly, two legs of the bracket running transversely to the middle part are inserted into the receiving part and fastened there.

The object of the present invention is to show a way in which assembly can be facilitated.

This object is achieved by a device with the features specified in claim 1 and by a method according to claim 11. Advantageous further developments are the subject of subclaims.

According to the invention, the spring clip is not inserted into the receiving part with its two legs at the same time, but first only one end of the spring clip is inserted into the receiving part and then a pivoting movement of the spring clip is carried out through which the spring clip comes into its working position and its second end to the Recording part is brought. In a heating device according to the invention, the receiving part forms an abutment which is designed in such a way that, when the spring clip is installed, it allows the spring clip to pivot about its first end in order to bring the spring clip into its working position in which it applies the contact pressure to the stack .

An advantageous development of the invention provides that the abutment, on which the first end of the spring clip is supported, positively absorbs a counterforce acting parallel to the contact force. In other words, the form fit acts parallel to the direction of the contact pressure. For example, the abutment can be a slot or undercut in which the first end of the spring clip is inserted. In this case, the spring clip can be L-shaped, so that only the second end is angled from the central part of the spring clip. Another possibility is that the first end of the spring clip is bent in an L-shape and is inserted in an opening, a slot and / or an undercut of the receiving part, in particular in an undercut opening. The L-shaped The bent end of the spring clip can run transversely to the middle part of the spring clip pressing on the stack, so that initially a section of the L-shaped end running transversely to the middle part connects to the middle part and then a transverse end section to this section.

The second end of the spring clip can for example be screwed or riveted to the receiving part. A separate fastening element, e.g. a screw or rivet can be used. However, it is also possible to design one or more rivets in one piece as a projection of the receiving part. During assembly, such a projection can be inserted through an opening in the spring clip and the projection can then be pressed flat or bent over, thereby forming a riveted connection.

Alternatively, the second end of the spring clip can also latch with the receiving part or snap into a recess provided for this purpose. For this, it is advantageous if the second end of the spring clip is pressed against the receiving part by a bias of the spring clip, the bias of the spring clip pressing the second end against the receiving part in a direction which runs transversely to the contact pressure with which the spring clip is Stack presses against the receiving part.

Both when the second end of the spring clip engages in this way and when the spring clip is riveted or screwed to the receiving part, the second end of the spring clip preferably runs transversely to the central part of the spring clip pressing on the stack. The second end of the spring clip is then bent in an L-shape. Alternatively, instead of the bent end, the front part can also have only two lateral approaches, in particular tabs, which are attached to the receiving part on both sides under tension, or the second end of the spring clip extends beyond the stack and its installation space so that a fastening between the spring clip and receiving part can be done.

A further advantageous development of the invention provides that the spring clip is designed asymmetrically within the scope of its manufacturing tolerances, preferably the two ends of the spring clip are designed differently within the framework of the manufacturing tolerances. The various embodiments disclosed in the application are characterized by the asymmetrical design of the spring clip ends and the receptacle for this purpose on the receptacle part. In an advantageous further development, the type of fastening of the two bracket ends is also different, for example in that the first end of the spring bracket is inserted into the receiving part and the second end of the spring bracket is screwed, riveted or latched to the receiving part. The main advantage of such an asymmetry is the saving in installation space. In addition, the stack can thus advantageously be protected on three sides from an encapsulation pressure. The fourth side is extremely advantageously excluded from extrusion coating.

The spring clip can be, for example, a leaf spring or an extruded profile, in particular made of aluminum or an aluminum-based alloy. In this way, the spring clip can advantageously dissipate heat from the rear side of the stack, which faces away from the receiving part, and introduce it into the receiving part, whereby the efficiency of the heating device is increased. Another advantageous development of the invention provides that the spring clip is a metal strip.

Another advantageous development of the invention provides that the stack contains a plastic frame which positions the heating resistor or the heating resistors and also holds the contact plate, one of the contact plates or both contact plates and / or the insulation layer. The assembly can be simplified by such a plastic frame, since the stack can thus be combined into an easily manageable unit and the stack can also be positioned on the receiving part.

During manufacture, the receiving part can be processed before the stack is placed on top of it in such a way that the heat transfer surface of the receiving part is transferred to the receiving part via the heat generated by the PTC heating resistor passes over, is leveled. The receiving part is preferably leveled by plastic deformation, for example by pressing on a stamp.

The receiving part is preferably made of metal, for example aluminum or an aluminum-based alloy. The receiving part and the stack are preferably at least partially surrounded by a plastic jacket, in particular encapsulated, which advantageously protects the heating device from an aggressive medium. For this purpose, the stack is extremely advantageously surrounded on three sides by a wall of the receiving part, extremely preferably by a wall which is higher than the stack on all three sides. As a result, the stack is well protected against the plastic material that hits it with high pressure during injection molding. The remaining open front side with the electrical connections can also be largely covered by the spring clip, if present also by the frame, so that the PTC resistor is adequately protected here as well. However, the connection front is extremely preferably excluded from the extrusion coating.

Fig.1

ein Ausführungsbeispiel einer erfindungsgemäßen Heizvorrichtung;

Fig. 2

eine Schnittansicht zu Fig. 1;

Fig. 3

eine schematische Ansicht eines weiteren Ausführungsbeispiels;

Fig. 4

eine schematische Ansicht eines weiteren Ausführungsbeispiels;

Fig. 5

eine schematische Ansicht eines weiteren Ausführungsbeispiels.

Fig. 6

eine schematische Ansicht eines weiteren Ausführungsbeispiels.

Fig. 7

eine schematische Ansicht eines weiteren Ausführungsbeispiels

Further details and advantages of the invention are explained using exemplary embodiments of the invention with reference to the accompanying drawings. Identical and corresponding components are provided therein with the same reference numbers. Show it:

Fig.1

an embodiment of a heating device according to the invention;

Fig. 2

a sectional view too Fig. 1 ;

Fig. 3

a schematic view of a further embodiment;

Fig. 4

a schematic view of a further embodiment;

Fig. 5

a schematic view of a further embodiment.

Fig. 6

a schematic view of a further embodiment.

Fig. 7

a schematic view of a further embodiment

The ones in the Figures 1 and 2 The heating device shown has a receiving part 1 which is heated by one or more ceramic PTC heating resistors 2. The receiving part 1 is only partially shown in the figures for the sake of simplicity. The receiving part 1 can, for example, be a housing of a delivery module for urea solution or a pump housing or a part of such a housing. In the figures, therefore, only those areas of the receiving part 1 are shown that are relevant for understanding the heating device.

In the exemplary embodiment shown, at least one ceramic heating resistor 2 is arranged between two contact plates 3, 4. If the receiving part is made of metal, one of the contact plates 3, 4 can be dispensed with and the receiving part 1 can be used as a ground contact. The contact plates 3, 4 rest on the heating resistor 2 and ensure electrical contact. On its side facing away from the heating resistor 2, the contact sheet 4 has an insulating layer 5, for example made of electrically insulating ceramic, such as aluminum oxide, or plastic.

The heating resistor 2, the contact plates 3, 4 and the insulation layer 5 form a stack which is pressed against the receiving part 1 by a spring clip 6. The receiving part 1 forms an abutment on which a first end 6a of the spring clip 6 is supported. The abutment can for example be an undercut 9 in which the first end 6a of the spring clip 6 is inserted. The spring clip 6 generates a pressing force F with which the stack is pressed against the receiving part 1. The abutment, on which the first end 6a of the spring clip 6 is supported, positively absorbs a counterforce G acting parallel to the contact force F. The form fit thus acts in the direction of the counterforce G and thus limits a movement of the first end 6a of the spring clip 6 in the direction of the counterforce G.

The abutment is designed in such a way that it allows a pivoting movement of the spring clip 6 about its first end 6a during the assembly of the spring clip 6, by which the spring clip 6 is brought into its working position, in which it applies the pressing force to the stack. After this pivoting movement, the second end 6b of the spring clip 6 is then attached to the receiving part 1.

In the figures, the second end 6b of the spring clip 6 is fastened to the receiving part 1 by means of one or more screws 7. Alternatively, the spring clip 6 can, for example, also be riveted or latched to the receiving part 1.

The one in the Figures 1 and 2 The embodiment shown, the second end 6b of the spring clip 6 is bent L-shaped and the spring clip 6 is L-shaped overall. It is possible to deviate from this shape, for example in that the spring clip 6 is overall I-shaped and the second end 6b is screwed or riveted to the receiving part 1. Another possibility is that the first end 6a of the spring clip 6 is L-shaped, for example in FIG Figures 3 and 4 shown schematically. In the schematically illustrated embodiment of the Fig. 3 the second end 6b of the spring clip 6 is screwed to the receiving part 1. In Fig. 4 the second end 6b of the spring clip 6 is locked to the receiving part 1.

The second end 6b of the spring clip 6 is in the embodiment of Fig. 4 is pressed against the receiving part 1 by a bias of the spring clip 6. The bias of the spring clip 6 presses the second end 6b in a direction Q against the receiving part 1, which runs transversely to the contact pressure F with which the spring clip 6 presses the stack against the receiving part 1.

In Fig. 5 shows the receiving part 1 as in FIG Fig. 1, 2 an undercut 9, the upper wall of the undercut 9 also having a slot 10. At its first end, the spring clip 6 has an attachment which is suitable for engaging the slot 10 in a form-fitting manner. The second ending is like in Fig. 4 designed. This design advantageously allows the stack to be surrounded on three sides, including the spring clip, with a wall so that the stack is well protected from the overmolding pressure.

Figures 6 and 7 still show variants Fig. 5 . At Fig. 6 the undercut 9 is directed away from the stack and the first bracket end is configured approximately U-shaped. The advantage of this variant is that there is no need for an additional slot in the receiving part. In a variant after Fig. 7 if the receiving part has a straight extension which has only one slot 10. The spring clip itself can as with Fig. 5 be designed.

The spring clip 6 is a metal strip in the illustrated embodiments. In this way, a large-area contact with the stack is advantageously generated, so that generated heat can be introduced not only from a front side of the stack directly into the receiving part 1 but also from the rear of the stack via the spring clip 6 into the receiving part 1. The spring clip 6 can be a leaf spring which is bent in a suitable manner. However, the spring clip 6 is preferably an extruded profile, for example made of aluminum or an aluminum-based alloy.

In order to simplify the assembly, the stack can contain a plastic frame 8 which connects the heating resistor (s) 2, the contact plate (s) 3, 4 and / or the insulation layer 5 to form an easily manageable unit.

List of reference symbols

1

Receiving part

2

Heating resistor

3

Contact sheet

4th

Contact sheet

5

Insulation layer

6th

Spring clip

6a

first end

6b

second end

7th

screw

8th

Plastic frame

9

Undercut

10

slot

F.

Contact pressure

G

Counterforce

Q

direction

Claims (11)

Heater with a ceramic heating resistor (2), a contact plate (3, 4) on which the heating resistor (2) rests, an insulation layer (5) which covers a side of the contact plate (4) facing away from the heating resistor (2), the heating resistor (2), the contact plate (3, 4) and the insulation layer (5) forming a stack, a receiving part (1) in which the stack is arranged, and a spring clip (6) which presses the stack with a pressing force (F) against the receiving part (1), the receiving part (1) forming an abutment on which a first end (6a) of the spring clip (6) is supported, characterized in that the abutment is designed in such a way that when the spring clip (6) is installed it allows a pivoting movement of the spring clip (6) around its first end (6a) in order to bring the spring clip (6) into its working position, in which it applies the contact pressure ( F) applies to the stack. Heating device according to Claim 1, characterized in that the abutment on which the first end (6a) of the spring clip (6) is supported positively receives a counterforce (G) acting parallel to the contact pressure (F). Heating device according to one of the preceding claims, characterized in that the first end (6a) of the spring clip (6) is inserted into the receiving part (1). Heating device according to one of the preceding claims, characterized in that a second end (6b) of the spring clip (6) is screwed or riveted to the receiving part (1). Heating device according to one of Claims 1 to 4, characterized in that the second end (6b) of the spring clip (6) is latched to the receiving part (1). Heating device according to one of the preceding claims, characterized in that the second end (6b) of the spring clip (6) is bent in an L-shape. Heating device according to one of the preceding claims, characterized in that the second end (6b) of the spring clip (6) is pressed against the receiving part (1) by prestressing the spring clip (6), the prestressing of the spring clip (6) being the second end (6b) presses against the receiving part (1) in a direction (Q) which runs transversely to the pressing force (F) with which the spring clip (6) presses the stack against the receiving part (1). Heating device according to one of the preceding claims, characterized in that the spring clip (6) is L-shaped. Heating device according to one of the preceding claims, characterized in that the spring clip (6) is a metal strip. Heating device according to one of the preceding claims, characterized in that the spring clip (6) is designed asymmetrically within the framework of its manufacturing tolerances, preferably the two ends (6a, 6b) of the spring clip (6) are designed differently within the framework of the manufacturing tolerances. Method for assembling a heating device, wherein a stack of at least one contact sheet (3, 4), a ceramic heating resistor (2) and an insulating part (5) is arranged in a receiving part (1), and a spring clip (6) is attached to the receiving part (1), which then presses the stack against the receiving part (1), characterized in that
a first end (6a) of the spring clip (6) is inserted into an abutment formed by the receiving part (1), the spring clip (6) then through a Pivoting movement is brought into its working position and the second end (6b) of the spring clip (6) is attached to the receiving part (1).

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