Electric heating device

Abstract

The invention relates to an electrical heating device (2) with improved thermal properties, comprising a housing (4) and a layered structure (14) located within the housing (4), the layered structure (14) comprising at least one heat-generating layer (18) formed by an electrical heating device (24) and at least one heat-dissipating layer (16) which is connected to the heat-generating layer (18) in a thermally conductive manner, the invention relates to a heat-generating layer (18), in particular for a motor vehicle, comprising a heat-generating layer (18) and formed by a meandering curved metal strip (30) which forms heating fins (32) extending substantially perpendicular to the heat-generating layer (18), two adjacent heating fins (32) being connected to each other by a bending region (34) which bears against the heat-generating layer (18) in a heat-conducting manner, the bending region (34) forming a flattened heat output surface (38).

Description

Technical Field

[0001] This invention relates to an electric heating device, comprising a housing and a layered structure located within the housing. The layered structure includes at least one heating layer and at least one heat dissipation layer. The at least one heating layer is typically formed by an electric heating device. Background Technology

[0002] For example, such an electric heating device is known from EP2298582A1.

[0003] The heating layer is composed of meandering metal strips. After this meandering, the metal strips have heating ribs extending substantially perpendicular to the heating layer. Therefore, the heating ribs correspondingly bridge the distance between the heating layer and the opposing layers in the layered structure. In this invention, the opposing layers can also be composed of metal strips that separate another heating layer from the adjacent heating layer and form a contact surface for two adjacent corrugated rib layers. However, this opposing surface can also be the contact surface of another heating layer.

[0004] Due to the meandering bends of the metal strips, each corrugated rib layer has a bending region. These bending regions form the contact areas with adjacent layers. In the prior art, the individual heating ribs of the corrugated rib layer are connected to each other only through simple bending regions. Because as many heating ribs as possible must be arranged sequentially within the narrow longitudinal space of each layer, the bending radius is relatively small. Therefore, in the prior art, the bending regions only adhere to the heating layer in a linear fashion. In a cross-sectional view of the layered structure, the bending regions adhere to the heating layer at specific points. The linear shape is determined by the width of the metal strips constituting the corrugated rib layer. Summary of the Invention

[0005] The present invention is intended to provide an apparatus of the type described above with higher thermal performance.

[0006] To address this problem, the present invention proposes to provide a flattened heat output surface for the curved region.

[0007] By flattening the surface, the heat output surface between adjacent heating fins is expanded, thereby improving the heat transfer between the heating layer and the heat dissipation layer, thus achieving improved thermal performance of the electric heating equipment.

[0008] The flattened heat output surface can be formed by a suitable metal strip forming process. The flattened heat output surface can also be formed by post-processing the corrugated rib layer and its curved areas, in particular by grinding or similar post-processing, to flatten the initially strictly convex curved areas, thereby forming a substantially flattened heat output surface that can be closely attached to the regularly flattened outer surface of the heating layer.

[0009] This invention represents an improvement over the prior art. In the aforementioned prior art, adjacent heating fins intersect at a point that determines the height of the heating layer and thus defines the corresponding area where the corrugated fin layer abuts against the heat dissipation layer.

[0010] According to a preferred design of the invention, the curved region may include a first curved portion and a second curved portion. These two curved portions are spaced apart from each other longitudinally and abut against the heating layer in a thermally conductive manner. Therefore, the curved region no longer has only one curved portion formed by bending, as in the prior art, in which two heating ribs intersect at a point or line and abut against the heating layer in the form of convex protrusions. Preferably, at least two, and possibly three or more, such protrusions are provided in a curved region.

[0011] To provide a defined contact surface between the heat dissipation layer and the heat generation layer, a groove is preferably provided between the first and second curved portions. The curved portions are typically formed as strictly convex shapes. Therefore, there is a concave region between the two curved portions (viewed from the contact surface of the heat generation layer), which ensures that the convex curved portion abuts against the heat generation layer in a predetermined manner.

[0012] Of course, the aforementioned feasible solution for increasing the heat output surface can be configured with opposite sides along the height direction of the corrugated fin layer. According to this solution, the increase in heat output surface originates entirely from improvements to the meandering metal strips constituting the corrugated fin layer. The heating layer can be bonded or welded to the heat dissipation layer. This connection method can expand the thermally conductive contact area between the corrugated fin layer and the heating layer. However, according to the present invention, the heat output surface is entirely composed of meandering metal strips. Therefore, solder or adhesive is not considered in expanding the heat output surface.

[0013] As known from EP2298582A1 or EP1564503A1, the layered structure is preferably disposed within the housing in a thermally conductive manner by the preload of an elastic element. This elastic element preferably extends as a spring element along the entire length of the layered structure, supporting the layers against each other. Therefore, this preferred embodiment eliminates the need for material locking connections between the layers, and in particular, eliminates the need to bond or weld the corrugated rib layer to the heating layer.

[0014] The shell can be a frame-like shell with shell openings that are opposite each other, allowing the medium to be heated to pass through, and the layered structure is substantially exposed between the shell openings.

[0015] The heating layer may have contact plates arranged parallel to each other in a conventional manner, which serve as conductive elements in contact with the electric heating elements. Typically, multiple electric heating elements are arranged sequentially along the longitudinal direction of the layered structure. The electric heating elements are preferably composed of PTC elements. Each electric heating element can be fixed between two contact plates by a positioning frame, thereby giving the heating elements a predetermined distribution in the longitudinal direction of the layered structure. Attached Figure Description

[0016] More details and advantages of the present invention can be derived from the description of the embodiments in conjunction with the accompanying drawings, wherein:

[0017] Figure 1 A cross-sectional view of an embodiment of the electric heating device is shown;

[0018] Figure 2 Show Figure 1 Enlarged view of detail II in the middle;

[0019] Figure 3A The bending area of ​​the conventional heating layer is shown;

[0020] Figure 3B The curved region of the second embodiment of the present invention is shown. Detailed Implementation

[0021] Figure 1 A cross-sectional view of the electric heating device 2 with a housing 4 is shown, the housing being formed as a plastic frame with longitudinal beams 6 and transverse beams 8. The elastic preload device 10 and... Figure 1 The longitudinal beams 8 shown extend adjacently and parallel to each other. The elastic preload device has a spring element 12 as an elastic element, which can be initially inserted into the housing 4 without being tightly closed as described in EP2298582A1, and can be tightly closed in the housing by relative movement.

[0022] Reference numeral 14 indicates a layered structure comprising multiple heat dissipation layers 16, with heat-generating layers 18 housed between them. In this case, the heat-generating layers include two parallel contact plates 20 and PTC elements 22 disposed therebetween. These PTC elements are arranged sequentially along the longitudinal direction L and constitute heating elements according to the present invention. The two contact plates 20 and the PTC elements 22 constitute an electric heating device 24.

[0023] Figure 2The image shows enlarged details of the heat dissipation layer 16. This layer 16 comprises meandering metal strips 30 forming multiple heating ribs 32 extending perpendicular to the longitudinal direction L. These heating ribs 32 are shaped by uniformly bending the metal strips 30. The bending creates corresponding bending regions 34 at the respective ends in the height direction H. In this case, the corresponding bending region 34 begins at a convex bend 36 inclined from the heating rib 32.

[0024] According to Figure 2 In this embodiment, a substantially linear heat output surface 38 is formed on the end of the convex bend 36 and between the heating ribs 32 forming the corresponding bend 36 (specifically, at the front convex end of each convex bend 36). Between the two heat output surfaces 38, a groove 40 is provided at the connection formed between adjacent heating ribs 32 by a bent metal strip 30. Both the groove 40 and the convex bend 36 have the same bending radius. In this embodiment, the bending radius is 0.5. In this embodiment, the extension of the bent region 34 in the longitudinal direction L is approximately 2 mm.

[0025] The convex bending portion 36 forms a first bending portion 42 and a second bending portion 44, forming a groove 40 between the first bending portion and the second bending portion, and transitioning to a heating rib 32 on the outside.

[0026] like Figure 2 As shown, adjacent curved regions 34 are in direct contact with each other. Therefore, the outer surfaces of the heating ribs 32 forming different curved regions 34 are in direct contact with or slightly outside the curved regions 34 in the height direction H.

[0027] This makes the heat output surface 38 in each curved region 34 larger than in a conventional design due to the flattening process.

[0028] Figure 3A The conventional design is shown. Here, the curved region 50 forms a single convex tip 52, and the corresponding heat dissipation layer 16 is attached to the associated heat dissipation surface with this tip.

[0029] Figure 3B An alternative embodiment of the invention is shown. Compared to the prior art, the tip 52 is here flattened by machining, for example, grinding. According to this variation of the invention, the curved region 34 correspondingly forms a flat heat output surface 38, which is flatter than... Figure 3A The heat output surface 54 of the prior art shown is larger, at least 5 times larger.

[0030] This surface is at least 4 times larger than the heat output surface formed by the tip 52, preferably at least 5 times larger. According to Figure 3AThe cross-sectional view shows that the heat output surface is dotted, thus appearing as a line across the entire width of the metal strip 30.

[0031] Of course, according to Figure 2 The illustrated embodiments can also be used with Figure 3B The modified design shown is combined to further increase the heat output surface 38 of the heat dissipation layer 16. In addition, besides Figure 3B In addition to the two curved sections 42 and 44 shown, a third or fourth curved section can also be formed by a single curved region 34.

[0032] List of reference numerals

[0033] 2. Electric heating equipment

[0034] 4. Shell

[0035] 6 Longitudinal beams

[0036] 8 crossbeams

[0037] 10. Elastic preload device

[0038] 12 Spring Elements

[0039] 14 Layered structure

[0040] 16 Heat dissipation layer

[0041] 18 Heating Layer

[0042] 20 Contact Plate

[0043] 22 PTC components

[0044] 24 Electric heating device

[0045] 30 Metal strips

[0046] 32 heating fins

[0047] 34. Curved area

[0048] 36. Convex bending section

[0049] 38 Heat output surface

[0050] 40 grooves

[0051] 42 First bending section

[0052] 44 Second bending section

[0053] 50 Curved area

[0054] 52 Tip

[0055] 54 Heat output surface

[0056] L longitudinal

[0057] H (height direction)

Claims

1. An electric heating device (2), comprising a housing (4) and a layered structure (14) located within the housing (4), wherein, The layered structure (14) includes at least one heating layer (18) formed by an electric heating device (24) and at least one heat dissipation layer (16), the heat dissipation layer being thermally connected to the heating layer (18) and formed by meandering metal strips (30), the metal strips forming heating ribs (32) extending substantially perpendicular to the heating layer (18), wherein two adjacent heating ribs (32) are connected to each other by a curved region (34) that abuts against the heating layer (18) in a thermally conductive manner. Its features are, The curved region (34) forms a flattened heat output surface (38).

2. The electric heating device (2) according to claim 1, characterized in that, The curved area (34) is flattened by post-processing the metal strip (30).

3. The electric heating device (2) according to claim 1, characterized in that, The curved region (34) includes a first curved portion (42) and a second curved portion (44), wherein the first curved portion (42) and the second curved portion (44) are spaced apart from each other along the longitudinal direction of the heating layer (18) and are attached to the heating layer (18) in a thermally conductive manner.

4. The electric heating device (2) according to claim 3, characterized in that, A groove (40) is provided between the first curved portion (42) and the second curved portion (44).

5. The electric heating device (2) according to claim 1, characterized in that, Adjacent curved areas (34) are directly adjacent to each other.

6. The electric heating device (2) according to claim 1, characterized in that, The thickness of the metal strip (30) is between 0.1 mm and 0.5 mm.

7. The electric heating device (2) according to claim 1, characterized in that, The layers (16, 18) of the layered structure (14) are brought into contact with each other in a thermally conductive manner by the pre-tightening force of the elastic element (12).

8. The electric heating device (2) according to claim 7, characterized in that, Adjacent curved areas (34) are directly adjacent to each other.

9. The electric heating device (2) according to claim 1, characterized in that, The heating layer (18) includes contact plates (20) arranged parallel to each other and electric heating elements, particularly PTC elements (22), disposed between the contact plates and in electrical contact with the contact plates.

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