DE102017123549A1 - tank heater - Google Patents

Abstract

Described is a tank heater with a PTC heater, which includes a PTC heating resistor (1) and a contact element (2), a housing part (6) made of metal, a spring element (5) made of metal, which generates a spring force, the PTC Heater against a heat transfer surface of the housing part (6) presses, and a plastic sheath (7) surrounding the housing part (6), the spring element (5) and the PTC heater. According to the invention, it is provided that the spring element (5) is latched or caulked to the housing part (6).

Description

A tank heater with the features specified in the preamble of claim 1 is known from DE 10 2014 212 544 A1 known.

Tank heaters for heating liquids in motor vehicles, such as urea solution or water, have a metal housing in which a PTC heater is arranged with a PTC heating resistor and a contact element, and a plastic sheath, which protects the metal housing from contact with liquid. For the metal housing extruded profiles, such as in the DE 11 2006 001 103 B4 known tank heating, or castings, such as in the case of DE 10 2014 212 544 A1 known tank heating, used.

Extruded profiles allow a very good thermal coupling of the PTC heating resistor to the metal housing by simple means by the extruded profile is pressed after the introduction of the PTC heater.

However, the possible shapes of the metal housing are limited, which is why increasingly castings for metal housing of tank heaters are used. Castings also allow the use of less expensive alloys, but make it difficult a good thermal coupling of the PTC heater to the metal housing, in particular because no channels or pockets can be produced with low-cost alloys, record the PTC heater and then can be pressed.

At the time of the DE 10 2014 212 544 A1 known tank heater therefore a steel spring plate is used, which is fixed to retaining ribs of the housing part, wherein the retaining ribs are compressed after setting to press the PTC heater with sufficient pressure against a heat transfer surface of a housing part and so a sufficient thermal contact between PTC heater and Produce metal housing.

Object of the present invention is to show a way, as in a tank heater whose metal housing is a casting, the heat coupling of the PTC heater can be improved.

This object is achieved by a tank heater with the features specified in claim 1. Advantageous developments of the invention are the subject of dependent claims.

In order to improve the heat coupling, a spring element is attached to the housing part prior to the sheathing, which generates a spring force which presses the PTC heater against the heat transfer surface. The spring element is preferably made of an alloy based on aluminum. Aluminum alloys have a good thermal conductivity, so that heat generated by the PTC heater can advantageously also be dissipated via the spring element.

According to the invention, the spring element is latched or caulked to the housing part. For example, the spring element can be attached to the housing part by being clipped onto the housing part. Advantageously, such a simple production can be realized. In addition, in the latching or caulking of the spring element with the housing part less the risk that form metal chips that can cause electrical problems, as in the conventional insertion of a spring plate into a groove.

A further advantageous development of the invention provides that the housing part on opposite sides of the heat transfer surface has walls which have an undercut, with which the spring element is hooked. The spring element may for example have two strips with latching hooks, between which extends a resilient lid surface. The spring element can thus form part of the housing in this way and allow easy assembly of the housing.

A further advantageous development of the invention provides that the spring element is an extruded profile. In this way, a cost-effective production is possible. Advantageously, an extruded profile can also be well rounded prior to assembly, so that no more sharp edges are present when encapsulating with plastic.

In the manufacture of the tank heater, before being connected to the PTC heater, the casting may be machined by flattening the heat transfer surface of the housing portion that transfers the heat generated from the PTC heater resistor to the housing portion. Preferably, the housing part is flattened by plastic deformation, for example by pressing a punch. But it is also possible a leveling by a rolling tool. Another possibility is the leveling over a machining such. Milling or grinding.

The casting can be made for example by die casting, such as an alloy based on aluminum. The surfaces of a casting are generally not as flat or smooth as in an extruded profile. By machining the casting, it is therefore possible to achieve improved thermal contact between the PTC heater and the housing part. The inventively preferred Leveling of the heat contact surface by pressing a punch can be carried out with little effort, optionally, the force acting on the heat contact surface punch can be supplemented by a shaped to match the opposite surface of the housing part lower punch.

The PTC heater may include one or more PTC heating elements and one or more contact elements. In the simplest case, the metal housing is used for electrically contacting the PTC heating element or the PTC heating elements, so that a single contact element, for. B. a contact plate, sufficient. When the metal shell is electrically isolated from the PTC heater (s), two contact elements are needed. PTC heating element (s) and contact element (s) can be held by a plastic frame, which can also carry an insulator that electrically isolates the or one of the contact elements of the metallic housing part. The insulator may be, for example, a ceramic plate, such as alumina, or a plastic film. But it is also possible to use two electrically insulated housing parts for electrical contacting of the PTC heating element or the PTC heating elements.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

• 1 eine Schnittansicht einer Tankheizung;
• 2 die Tankheizung von 1 ohne Kunststoffmantel und Federelement;
• 3 das Federelement der in 1 gezeigten Tankheizung;
• 4 einen perspektivischen Längsschnitt entlang der Linie A - A durch -das Gussteil der in 1 gezeigten Tankheizung;
• 5 eine Schnittansicht eines weiteren Ausführungsbeispiels einer Tankheizung;
• 6 eine Schnittansicht eines weiteren Ausführungsbeispiels einer Tankheizung;
• 7 ein Ausführungsbeispiel eines Gehäuseteil zum Verstemmen mit einem Federelement und
• 8 ein weiteres Ausführungsbeispiel einer Tankheizung ohne den Kunststoffmantel.

Further details and advantages will be explained with reference to embodiments of the invention with reference to the accompanying drawings. Identical and corresponding components are provided therein with matching reference numerals. Show it:

• 1 a sectional view of a tank heater;
• 2 the tank heating of 1 without plastic sheath and spring element;
• 3 the spring element of in 1 shown tank heater;
• 4 a perspective longitudinal section along the line A - A through - the casting of in 1 shown tank heater;
• 5 a sectional view of another embodiment of a tank heater;
• 6 a sectional view of another embodiment of a tank heater;
• 7 an embodiment of a housing part for caulking with a spring element and
• 8th another embodiment of a tank heater without the plastic jacket.

In the 1 shown in a sectional view tank heater includes a PTC heater, the at least one PTC heating resistor 1 contains and additionally, for example, a contact element 2 as well as an insulator 3 and a plastic frame 4 which holds the various components of the PTC heater. The PTC heater is powered by a spring element 5 against a heat transfer surface 66 of the housing part 6 pressed over by the PTC heating resistor 1 generated heat on the housing part 6 passes.

In the embodiment shown, the PTC resistor is located 1 flat on the heat transfer surface 66 of the housing part, since the PTC resistor 1 over the housing part 6 is contacted electrically. In another embodiment, for example when the PTC heating resistor is electrically insulated on both sides of the housing and is electrically contacted by two contact elements, but also another component of the PTC heater can be flat on the heat transfer surface 66 abut, such as a ceramic plate or other insulator.

The housing part 6 is a casting made, for example, by die casting. Before the PTC heater with the housing part 6 is connected, the heat transfer surface 66 of the housing part 6 leveled by plastic deformation, for example by pressing a stamp. In this way, the heat coupling of the PTC heater to the housing part 6 improved.

After leveling the heat transfer surface 66 of the housing part 6 by pressing a punch, the PTC heater is placed on the heat transfer surface 66 set and the spring element 5 on the housing part 6 clipped. After that, the housing part 6 and the spring element 5 and the arranged between them PTC heater with plastic encapsulated, so that these then from a plastic sheath 7 are protected from contact with a liquid to be heated.

The housing part 6 indicates on opposite sides of the heat transfer surface 66 walls 61 on, which have an undercut, with which the spring element 5 is hooked. The undercut can, for example, by a groove 62 in the relevant side wall 61 be formed. In this case, an upper, the undercut forming boundary surface extends 64 the groove 62 parallel to the heat transfer surface 66 and a lower boundary surface 65 the groove 62 diagonally to the upper one Boundary surface of the groove 62 , In other words, the groove spreads 62 ie in their longitudinal direction. In this way, the housing part can be 6 easier to remove from its mold. In 4 are in a sectional view of the housing part 2 the hidden cut edges of a longitudinal section through the housing part 2 shown by dashed lines to illustrate this.

This in 3 isolated spring element shown 5 is with the housing part 6 locked. The corresponding positive fit acts perpendicular to the heat transfer surface of the housing part 6 , The spring element 5 can do two bars 51 with snap hook 52 have, with the undercut of the opposite side walls 61 of the housing part 6 snag. For this purpose, the boundary surface is advantageous 64 , and / or the contacting with the boundary surface contact surface 54 the locking hook 52 inclined to the heat transfer surface 66 executed, so that the spring element 5 can safely stay locked. Between the bars 51 extends a resilient ceiling wall 53 , which presses against the PTC heater, for example, against an insulator 3 , such as a ceramic tile or plastic. The spring element 5 thus has a basically U-shaped configuration. Advantageously, the ceiling inner surface 55 at least before mounting a bent towards the center of the PTC heater out contour, whereby after hooking at least the central region of the PTC heater securely conducts heat with the heat transfer surface 66 and the spring element 5 connected is.

Both the spring element 5 as well as the housing part 6 may be made of an aluminum base alloy. While a low-cost standard cast alloy can preferably be used for the casting, this is the spring element 5 preferably made of a spring-hard alloy such as an AlMgSi alloy. The spring element 5 can be produced by extrusion, so be an extruded profile. Unlike a thin steel spring plate, where it is difficult to avoid sharp edges, an aluminum-based alloy spring element can easily have rounded edges. Is the spring element z. B. produced as an extruded part, so the edges after cutting can be such z. B. be reworked by sandblasting that the edges are rounded afterwards. As a result, the danger that the plastic sheath in contact with the edges ruptures at these edges is significantly reduced.

The housing part 6 may have further walls, for example a rear wall 63 which are transverse to the opposite side walls 61 , which have the undercut, runs. As a result, the PTC heater is adequately protected against the high-pressure injection-molded material from 3 sides. The remaining open front is largely through the front wall of the plastic frame 4 covered, so that here too the PTC heater is sufficiently protected. Otherwise, namely, the pressure during encapsulation of the spring force of the spring element 5 counteract.

5 shows a sectional view of another embodiment of a tank heater, which differs from the embodiment discussed above substantially by the orientation of the latching hooks 52 of the spring element 5 different. While in the embodiment of the 1 to 4 the snap hooks 52 of the spring element 5 are directed inward and facing each other, the locking hooks in the embodiment of 5 directed outward and away from each other. In spite of this, the PTC heater is tight with side walls 61 and to be able to enclose a back wall, the undercuts are not on the side walls here 61 attached, but on further outside additional side walls 67 ,

6 shows a sectional view of another embodiment of a tank heater. This embodiment differs from the embodiments described above essentially in that the spring element 5 by caulking on the housing part 6 is attached. In the embodiment shown, the housing part 6 protruding pins 8th , preferably on the front side of the walls 61 , The pins go through 8th Openings in the spring element 5 and are caulked on the top under bias with a tool such that a positive connection is produced. In 6 there is only one pin on each face 8th recognizable. Several pens 8th on each side are also possible. The pencils 8th can be integral with the housing part 6 be formed or manufactured separately. It is particularly preferred that the pins 8th are arranged laterally offset.

In 7 an alternative embodiment is shown in which on each side a single, elongated pin 8th With slightly tapered side surfaces an elongated opening in the spring element passes through. But it is also possible a variant 8th in which the spring element 5 between the spring element 5 outstanding rails 9 is inserted and the rails 9 partially caulked at the edge such that the caulked areas 10 the spring element 5 overlap under bias at the edge and thereby fix.

LIST OF REFERENCE NUMBERS

1

PTC heating element

2

contact element

3

insulator

4

Plastic frame

5

spring element

6

housing part

7

Plastic sheath

8th

pen

9

rail

10

caulked area

51

strip

52

latch hook

53

ceiling wall

54

contact area

55

Ceiling inner surface

61

Side wall

62

groove

63

rear wall

64

upper boundary surface

65

lower boundary surface

66

Heat transfer surface

67

additional sidewall

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014212544 A1 [0001, 0002, 0005]
• DE 112006001103 B4 [0002]

Claims (8)

Tank heating with a PTC heater, which includes a PTC heating resistor (1) and a contact element (2), a housing part (6) made of metal, a spring element (5) made of metal, which generates a spring force, the PTC heater against a heat transfer surface (66) of the housing part (6) presses, and a plastic jacket (7) surrounding the housing part (6), the spring element (5) and the PTC heater, characterized in that the spring element (5) with the housing part (6) is locked or caulked. Tank heating after Claim 1 , characterized in that the housing part (6) on opposite sides of the heat transfer surface (66) side walls (61, 67) which have an undercut, with which the spring element (5) is hooked. Tank heating after Claim 2 characterized in that the undercut in each of the opposed side walls (61,67) is formed by a groove (62), an upper undercut forming surface (64) of the groove (62) being parallel to the heat transfer surface and a lower one Limiting surface (65) of the groove (62) obliquely to the upper boundary surface of the groove (62). Tank heater according to one of the preceding claims, characterized in that the PTC heater comprises a plastic frame (4) comprising the PTC heating element (1), the contact element (2) and on the side facing away from the PTC heating element (1) of the contact element (2) arranged insulator (3) holds. Tank heating after Claim 4 , characterized in that the spring element (5) rests against the insulator (3). Tank heater according to one of the preceding claims, characterized in that the spring element (5) is an extruded profile. Tank heater according to one of the preceding claims, characterized in that the spring element (5) has two strips (51) with latching hooks (52), between which extends a resilient Deckenwandlfläche (53). Tank heater according to one of the preceding claims, characterized in that the spring element (5) is made of an alloy based on aluminum.

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