Heating system

Abstract

An electric heating device with a profile tube (1) in which a heating element (2) is arranged and from which a contact plate (3) projects, wherein the contact plate (3) forms a contact spring which resiliently presses against the heating element (2), characterized in that the contact plate (3) has at least two pressure areas which are displaceable relative to each other against spring force, wherein the pressure areas are planar and more than two pressure areas are arranged one behind the other in the longitudinal direction of the contact plate (3).

Description

[0001] The invention relates to a heating device comprising a profiled tube in which an electric heating element is arranged. Such a heating device with the features specified in the preamble of claim 1 is known from US 3,996,447 A. Similar heating devices are known from DE 10 2006 055 216 A1 and DE 10 2008 052 918 A1.

[0002] From DE 38 15 306 A1, a heating device is known which has a sleeve in which a heating element and a contact plate, which forms a contact spring that resiliently presses against the heating element, are arranged. A similar heating device is known from US 5 262 619 A.

[0003] From DE 103 60 159 A1, an electric heating device for heating the passenger compartment of automobiles is known, comprising a profile tube in which a heating element is arranged and from which a contact plate protrudes. Such heating devices have the advantage that the heating elements are well protected within the profile tubes, and direct contact with the medium to be heated is avoided. However, good heat dissipation from the heating element to the profile tube must be ensured. To achieve this, DE 103 60 159 A1 discloses the method of crimping the profile tubes after the heating elements have been inserted. In this process, two walls of the profile tube, running parallel to the plate-shaped heating element, are pressed inwards. In the finished heating device, the profile tube then has two concave walls between which the heating element is clamped.

[0004] The object of the present invention is to demonstrate a way in which the heat coupling of a heating element to a surrounding profile tube in an electric heating device can be improved.

[0005] This problem is solved by a heating device with the features specified in claim 1. Advantageous embodiments of the invention are the subject of dependent claims.

[0006] In a heating device according to the invention, the contact plate forms a contact spring that resiliently presses against the heating element. Therefore, crimping the profile tube is not necessary in a heating device according to the invention. Surprisingly, heating devices manufactured according to the invention exhibit better thermal coupling of the heating elements to the surrounding profile tubes than crimped profile tubes. When the side walls of a profile tube are crimped conventionally, ceramic PTC heating elements often break. While a heating device can still function with broken heating elements, the fragments are poorly positioned within the profile tube, resulting in reduced thermal coupling.

[0007] In contrast, the manufacture of a heating device according to the invention advantageously avoids any significant risk of breakage for ceramic heating elements. Because the contact plate forms a contact spring that resiliently presses against the heating element, consistently good contact across the entire surface of a heating element, and thus correspondingly good heat transfer, can be achieved in all heating devices of a production series without risk of breakage.

[0008] The contact plate forms a contact spring by having at least two pressure areas that are displaceable relative to each other against a spring force. One pressure area can thus press against one or more heating elements. This pressure area is displaceable against one or more further pressure areas that contact heating elements on the other side of the contact plate or carry an insulating layer and press against an inner wall of the profile tube.

[0009] Pressure zones can be formed, for example, by spring tabs that are cut out of the contact plate and bent outwards. It is possible to bend these spring tabs outwards from the plate on both sides. However, it is preferable for the spring tabs to be bent outwards from the plate only on one side. The remaining sections of the plate between and beside the spring tabs can then form further pressure zones that press against heating elements on the other side of the contact plate or against the inside of the profile tube.

[0010] Another way to create pressure points is to provide the contact plate with a series of raised and recessed areas. In the simplest case, the contact plate can be designed as a corrugated sheet, for example. However, it is better to make the raised and recessed areas flat, as this results in larger contact surfaces. The raised and recessed areas each form pressure points. Pressure points are preferably connected to adjacent pressure points via a sloping surface.

[0011] Further details and advantages of the invention are explained using the exemplary embodiment with reference to the accompanying drawings. Identical and corresponding components are designated by matching reference numerals. The drawings show: Fig. 1 an embodiment of a heating device in a longitudinal section; Fig. 2 a cross-sectional view of Fig. 1; Fig. 3 a longitudinal section of a further embodiment; Fig. 4 a cross-section to Fig. 3; Fig. 5 a longitudinal section of a further embodiment which is not the subject of the patent claims; Fig. 6 a cross-section to Fig. 5; and Fig. 7 a cross-section of a further embodiment which is not the subject of the patent claims.

[0012] The Fig. 1 and Fig. Figure 2 shows a longitudinal section of an electric heating device. The heating device has a profile tube 1 made of metal, for example, an aluminum-based alloy, in which ceramic PTC elements 2, for example, based on barium titanate, are arranged as resistance heating elements. In the illustrated embodiment, the heating elements 2 are electrically contacted on one side by the profile tube 1. On the other side, the heating elements 2 are contacted by a contact plate 3 that projects from the profile tube 1. The contact plate 3 forms a contact spring that resiliently presses against the heating elements 2. Fig. As shown in Figure 1, the contact plate 3 has a series of raised and recessed areas which form longitudinally arranged pressure zones. The pressure zones are flat and can be displaced against spring force perpendicular to a surface normal of the pressure zones. Adjacent pressure zones are connected to each other by inclined surfaces.

[0013] The contact plate 3, designed as a contact spring, can be manufactured cost-effectively as a stamped and bent part and presses the heating elements 2 against the inner walls of the profile tube 1 with a spring force, resulting in good thermal and electrical contact.

[0014] In the Fig. 3 and Fig. Figure 4 shows a further embodiment of a heating device in a longitudinal section and a cross-section. This heating device also consists of a profile tube 1 in which at least one ceramic PTC heating element 2 is arranged, which is electrically contacted by a contact plate 3 projecting from the profile tube 1. Fig. Figure 4 shows that the contact plate 3 is designed as a contact spring, having a C-shaped cross-section. This contact plate 3 also has several pressure zones, which, however, unlike the previous embodiment, do not extend consecutively along the longitudinal direction of the contact plate 3. Instead, longitudinal edges of the contact plate 3 each form a pressure zone that can be resiliently displaced relative to an intervening central zone.

[0015] Another difference from the exemplary embodiment of Fig. 1 and Fig. 2 consists in the fact that the contact plate 3 is not arranged between heating elements 2. In the exemplary embodiment of the Fig. 3 and Fig. 4 Only one inner wall of the profile tube 1 comes into contact with the heating element 2 or heating elements 2. An electrical insulating layer 4, for example a ceramic strip, is located against the opposite inner wall, against which the contact plate 3 presses.

[0016] In the Fig. 5 and Fig. Figure 6 shows another embodiment of a heating device in a longitudinal section and a cross-section. In this embodiment, the contact plate 3 forms a contact spring by having contact tongues cut out of it that spring against one or more PTC heating elements 2. Similar to the embodiment of Fig. 3 and Fig. 4 The contact plate 3 has an electrical insulation layer 4 on one side, for example made of aluminium oxide, which is pressed resiliently against an inside of the profile tube 1 by the contact plate 3.

[0017] In Fig. Figure 7 shows another embodiment of a heating device in cross-section. The contact plate 3 forms a contact spring by being bent around a bending axis running in its longitudinal direction. The contact plate thus has a C-shaped bend that extends in the longitudinal direction of the profile tube 1 essentially over its entire length. In contrast to the embodiment of the Fig. 4. However, this bend faces a side wall of the profile tube. The contact plate can therefore, with one of its two spring legs connected to each other via the bend, bear against one or more PTC heating elements 2 with an advantageously large surface area. Preferably, one of these two spring legs is flat to allow for maximum contact area.

[0018] In all described embodiments, the profile tube 1 electrically contacts the heating elements 2. However, it is also possible to electrically insulate the profile tube 1 from the heating elements 2 and to provide additional contact plates for contacting the PTC elements 2. These contact plates have an electrical insulating layer on their back side, which rests against the inside of the profile tube. The additional contact plate(s) can also be designed as contact springs. However, this is not necessary. The additional contact plate(s) can also be designed as simple sheet metal strips, since a single contact plate designed as a contact spring is sufficient to clamp all the components arranged in the profile tube against each other. Reference figures 1 profile tube 2 heating elements 3 Contact plate 4 Insulation layer

Claims

[1] Electric heating device with a profile tube (1) in which a heating element (2) is arranged and from which a contact plate (3) protrudes, wherein the contact plate (3) forms a contact spring which springs against the heating element (2), characterized by that the contact plate (3) has at least two pressure areas which are displaceable relative to each other against spring force, wherein the pressure areas are planar and more than two pressure areas are arranged one behind the other in the longitudinal direction of the contact plate (3). [2] Heating device according to claim 1, characterized by , that the pressure areas are movable relative to each other perpendicular to a surface normal of one of the pressure areas [3] Heating device according to one of the preceding claims, characterized by , that at least one of the pressure areas is formed by a spring tongue cut out of the contact plate (3). [4] Heating device according to one of the preceding claims, characterized by , that at least one of the pressure areas is arranged between two pressure areas, to which it is connected by an inclined surface. [5] Heating device according to any of the preceding claims, characterized by that the pressure areas are designed as a series of raised and recessed areas [6] Heating device according to any of the preceding claims, characterized by , that the contact plate (3) is a stamped and bent part.

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