Exhaust gas heater

Abstract

The present invention relates to an exhaust heater for an exhaust device for an internal combustion engine, the exhaust heater comprising: a support arrangement structure (24); a heat conductor arrangement structure (18) supported on the support arrangement structure (24), the heat conductor arrangement structure having at least one current-carrying heat conductor (14, 16), the at least one heat conductor (14, 16) being electrically insulated about the support arrangement structure (24) by at least one support arrangement structure support unit (38, 40) or / and at least one heat conductor (14) being electrically insulated about another heat conductor (16) by at least one heat conductor support unit (42); a connection arrangement structure (31) for fixedly connecting the heat conductor arrangement structure (18) to the support arrangement structure (24); and a length compensation arrangement structure (44) for compensating for different thermal expansion of the exhaust heater components.

Description

Technical Field

[0001] The present invention relates to an exhaust heater that can transfer heat in the exhaust system of a motor vehicle to the exhaust gas flowing in the exhaust system and injected from the internal combustion engine, so as to bring the system area with respect to the exhaust heater, such as the catalytic converter or particulate filter, to the operating temperature more quickly, especially during the start-up phase of the internal combustion engine. Background Technology

[0002] An exhaust heater is known from the later-published German patent application DE102021109568, in which two heat conductors of a heat conductor arrangement, provided by being separated from flat materials, are successively arranged between two plate-shaped, substantially plate-like support elements of a support arrangement structure along the main exhaust flow direction corresponding to the longitudinal direction of the exhaust heater. The layered structure of the support elements and the heat conductors arranged therebetween is held together by a connecting arrangement structure having multiple bolt-like connecting elements. To achieve electrical insulation of the heat conductors with respect to the support elements or with respect to each other, multiple support units made of electrically insulating materials, such as ceramic materials, are respectively arranged between them. The layered structure of the support elements, heat conductors, and support units arranged therebetween is held together by the connecting elements of the connecting arrangement structure. Summary of the Invention

[0003] The objective of this invention is to provide an exhaust heater in which the support arrangement structure and the heat conductor arrangement structure are stably maintained together regardless of temperature.

[0004] According to the present invention, the task is solved by an exhaust heater for an exhaust system of an internal combustion engine, the exhaust heater comprising:

[0005] Support structure layout;

[0006] A heat conductor arrangement structure supported on the support arrangement structure, the heat conductor arrangement structure having at least one current-carrying heat conductor, the at least one heat conductor being electrically insulated from the support arrangement structure by at least one support arrangement structure support unit or / and at least one heat conductor being electrically insulated from another heat conductor by at least one heat conductor support unit;

[0007] A connection arrangement structure for fixing the heat conductor arrangement structure to the support arrangement structure;

[0008] Length compensation arrangement structure used to compensate for different thermal expansion of exhaust heater components.

[0009] Because the different components of such an exhaust heater—specifically, the support arrangement, the heat conductor arrangement, the support units that support the heat conductor arrangement, and the connecting arrangement that provides a fixed connection—are typically constructed of different materials, they experience different thermally induced expansions when heated by the exhaust gas flowing through the exhaust heater. At lower temperatures, the components held together by the connecting arrangement—the support arrangement, the heat conductor arrangement, and the support units—provide a stable composite structure. If, for example, the connecting arrangement expands more strongly than the components of the exhaust heater held together by them when heated by the exhaust gas flowing through the exhaust heater, the clamping may be lost, potentially causing relative movement of the exhaust heater with respect to the movable components, at least to a small extent, leading to damage and / or noise. This is avoided in the construction according to the invention by using a length-compensating arrangement to compensate for these different thermal expansions of the different components of the exhaust heater, such that the components are stably held together by the connecting arrangement regardless of the temperature of the exhaust heater components.

[0010] For ease of implementation, the connection arrangement may include at least one preferably bolt-shaped connection element, and the length compensation arrangement may include at least one length compensation element in the force transmission path between at least one connection element and the support arrangement or / and the heat conductor arrangement.

[0011] The support arrangement may include two successive support elements along the longitudinal axis of the exhaust heater, with the heat conductor arrangement accommodating therebetween. To reliably provide length compensation in such a layered configuration, the length compensation arrangement includes at least one length compensation element in the support path between at least one of the support elements and the heat conductor arrangement, or / and in the support path between two heat conductors of the heat conductor arrangement, or / and in the support path between at least one support element and at least one connecting element, in conjunction with at least one connecting element.

[0012] For this purpose, it can be specified, for example, that at least one, preferably each, length compensation element is disposed between the support element and the support unit of the support element, or / and at least one, preferably each, length compensation element is disposed between two heat conductors, or / and at least one, preferably each, length compensation element is disposed between the support area of ​​the support element and the connecting element supported on the support element.

[0013] To ensure that the length compensation arrangement is defined and positioned within the exhaust heater, it is proposed that at least one, preferably each, connecting element passes through at least one length compensation element and through at least one support element and / or at least one heat conductor support unit. Thus, a stack consisting of one or more support units and one or more length compensation elements, held together by said at least one connecting element, is provided in a manner corresponding to the at least one connecting element.

[0014] To provide length compensation functionality, at least one, preferably each, length compensation element can be constructed of a material having a larger coefficient of thermal expansion than the material of the at least one connecting element. This ensures that such a length compensation element expands more strongly than the one or more connecting elements when heated, so that the clamping of the different components of the exhaust heater generated by the connecting elements is also maintained when heated.

[0015] For example, when the at least one connecting element is constructed of a nickel-chromium alloy, the at least one length compensation element may be constructed of steel, preferably 1.4980 steel.

[0016] In another design, the length compensation function can be implemented by including at least one, preferably each, length compensation element as a preload element that can be elastically deformed.

[0017] For example, at least one, preferably each, length compensation element can be constructed as a disc spring or a wave spring.

[0018] For mechanical stability and resistance to exhaust, the support arrangement can be constructed of a metallic material. The heat conductor arrangement can also be constructed of a metallic material, particularly a metallic material that heats up due to its resistance when voltage is applied.

[0019] The present invention also relates to an exhaust device for an internal combustion engine, said exhaust device comprising at least one exhaust heater constructed according to the present invention. Attached Figure Description

[0020] The invention will then be described in detail with reference to the accompanying drawings. In the drawings:

[0021] Figure 1 A perspective view of the exhaust heater is shown;

[0022] Figure 2 Show Figure 1 A longitudinal sectional view of the exhaust heater;

[0023] Figure 3 The diagram shows a longitudinal sectional view of an exhaust heater, which has a support unit of a bracket arrangement structure arranged in a manner that is matched with connecting elements and a length compensation element of a length compensation arrangement structure.

[0024] Figure 4 This illustrates an alternative design type corresponding to Figure 3 The illustration;

[0025] Figure 5 This illustrates another corresponding alternative design type. Figure 3 The illustration. Detailed Implementation

[0026] exist Figure 1 and Figure 2 The diagram shows an exhaust heater 10 for an exhaust system 12 of an internal combustion engine, for example, in a motor vehicle. The exhaust heater 10 has two heat conductors 14 and 16 arranged sequentially along the longitudinal axis L of the exhaust heater, which are allowed to flow through the exhaust gas in the main exhaust flow direction H and have a heat conductor arrangement structure generally indicated by 18. These heat conductors are essentially circulated sequentially by the exhaust gas flowing in the main exhaust flow direction H. The heat conductors 14 and 16 are constructed substantially in a plate-like shape or from a flat material, and their structure, provided by utilizing multiple sections extending in a corrugated structure, is produced by separating them from a flat material blank, particularly a metal blank.

[0027] On the sides of the two heat conductors 14 and 16 that are opposite to each other along the longitudinal axis L of the exhaust heater, there are support elements 20 and 22 of a generally plate-like construction, which are generally indicated by 24. The plate-like support elements 20 and 22 are fixed to the generally cylindrical support housing 26 on their outer peripheral regions.

[0028] The two thermal conductors 14 and 16 can be connected in series or in parallel. For electrical connection to a power source, two connection units 28 and 30 are provided that penetrate the support housing 26 and are electrically connected to the thermal conductors 14 and 16 within the internal space surrounded by the support housing 26.

[0029] To achieve a stable composite structure, the two support elements 20, 22 and the heat conductors 14, 16 disposed therebetween and directly adjacent to each other are fixedly connected to each other by a connection arrangement structure 31 having multiple bolt-like connecting elements 32. The connecting elements 32 may, for example, be constructed as bolts having a rod 34 and a head 36. Nut elements 37 may, for example, be tightened onto the rod 34 to clamp the layered structure of the support elements 20, 22 and the heat conductors 14, 16 between the head 36 and the nut elements 37.

[0030] To achieve electrical insulation of the heat conductors 14 and 16 with respect to the support elements 20 and 22, which are typically constructed of metallic material, with respect to the support arrangement structure 24, a support arrangement structure support unit 38, constructed of an electrically insulating material, such as ceramic, and with its openings extending through the area of ​​the connected element 32, is provided between the heat conductor element 14 and the support element 20, for example, in a manner that mates with each connecting element 32. Similarly, a support element support unit 40 is provided between the heat conductor 16 and the support element 22, for example, in a manner that mates with each connecting element 32. The support element support units 38 and 40 may, for example, be substantially identical in structure to each other.

[0031] To support the two side-by-side heat conductors 14, 16 with electrical insulation relative to each other, heat conductor support units 42 are provided, for example, in a manner that corresponds to each connecting element 32. Each heat conductor support unit 42 is also constructed substantially in a plate-like form as one or more discs and is made of ceramic material. Where the heat conductors 14, 16 are penetrated by the connecting element 32, a sleeve-shaped insulating element 43 can be inserted into the opening formed in the heat conductors 14, 16 to achieve the defined positioning of the connecting element 32 within the opening provided in the heat conductors 14, 16.

[0032] Figure 3 The construction of the exhaust heater 10 is shown in relation to the connecting element 32, in which the different thermal expansions of the different components of the exhaust heater 10 are compensated by providing a length-compensating arrangement structure, generally indicated by 44. It should be considered that in the layered construction consisting of two support elements 20, 22 and heat conductors 14, 16, and support element support units 38, 40 or heat conductor support units 42 disposed therebetween, these different components have different structural materials, particularly different from the structural materials of the connecting element 32. Such different structural materials generally have different coefficients of thermal expansion, which may result in different thermally induced expansions when heated by the exhaust gas flowing through the exhaust heater 10, leading to losses in the clamping of the connecting element 32 in the cold state. The components of the exhaust heater 10 held between the head 36, which provides the support area for the connecting element 32, and the nut element 37 can then reach a state in which the components have a movement clearance relative to each other in the direction of the longitudinal axis L of the exhaust heater.

[0033] Such different thermal expansions are compensated for by the length compensation arrangement 44, so that the components of the exhaust heater 10, which are also held together by the connecting elements 32, are stably held together when clamped. To achieve this, the length compensation arrangement 44 includes, for example, a disc-shaped or washer-shaped length compensation element 46 configured to be matched with each connecting element 32. This length compensation element may pass through the connecting elements 32 or their rods 34, which are also matched as the different support units 38, 40, 42, so that a stack consisting of the support units 38, 40, 42 and the length compensation element 46 is stably held together transversely to the longitudinal axis L of the exhaust heater.

[0034] In the illustrated design example, a length compensation element 46 provided for the illustrated connecting element 32 is disposed between the support element 22, which is loaded by and supports the head 36 of the connecting element 32, and the adjacent support element support unit 40. The length compensation element 46 is constructed of a material having a larger coefficient of thermal expansion than the structural material of the connecting element 32. If the connecting element 32 expands along the longitudinal axis L of the exhaust heater when heated, the length compensation element 46 also expands in that direction, and more precisely, to a greater extent than the connecting element 32. It is also considered that the connecting element 32 has a much larger extension length along the longitudinal axis L of the exhaust heater than the length compensation element 46. Because the thermally induced relative length change of the connecting element 32 results in a relatively large absolute length change due to its relatively large extension length along the longitudinal direction L of the exhaust heater, the length compensation element 46 is constructed of a material whose relative length change is so large when heated that, although the extension length of the length compensation element 46 along the longitudinal axis L of the exhaust heater is shorter, the absolute length change of the length compensation element 46 at least compensates for the absolute length change of the connecting element 32. Also considered here are the other components of the exhaust heater 10 disposed between the two support elements 20, 22, namely the different support units 38, 40, 42, and the heat conductors 14, 16; and the support elements 20, 22 themselves, which, due to their heating, also experience at least a slight increase in their extended length along the longitudinal axis L of the exhaust heater, and thus have thereby compensated for a portion of the length variation of the connecting element 32. Only the portion of the absolute length variation of the connecting element 32 that is not compensated for by the length variation of these components must be compensated for by the length variation of the length compensation element 46.

[0035] If, for example, in Figure 3In the configuration shown, the two support elements 20 and 22 are constructed of steel plate material, the heat conductors 14 and 16 are constructed of metal material that can be heated by their resistance when voltage is applied, the different support units 38, 40, and 42 are constructed of ceramic material, and the connecting element 32 is constructed of metal material, such as nickel-chromium alloy material. The length compensation element 46 can be constructed of steel material, such as 1.4980 steel, in order to achieve compensation for the length variation of the connecting element 32.

[0036] It should be noted that the length compensation arrangement structure 44 preferably has such a length compensation element 46 in a manner that is matched with each connecting element 32 of the exhaust heater 10. It should also be noted that such a length compensation element 46 can also be provided at another location. For example, the length compensation element can be provided between the support element 20 and the support element support unit 38, or between the support element support units 38, 40 and the heat conductors 14 or 16 directly adjacent to them. The length compensation element 46 can also be positioned between two heat conductors 14, 16, for example between the heat conductor support unit 42 and one of the heat conductors 14, 16, or between the two disc-shaped components of the heat conductor support unit 42.

[0037] In relation to the extent to which thermally induced length changes of the connecting element 32 are compensated, it is also possible that multiple length compensation elements 46 are arranged, for example, at the positions listed above in the stacked composite structure.

[0038] An alternative design form in Figure 4 As shown in the diagram. This design differs substantially from the previously described construction in that the bolt-like connecting element 32 is fixedly connected to two support elements 20, 22 at their axial end regions by welding 48, 50 material lock-in. In this construction, the stack consisting of the support elements 20, 22, the heat conductors 14, 16, and the support units 38, 40, 42 can be clamped together during assembly, and in this state, the connecting element 32 is fixedly connected to the support elements 20, 22 at their two axial end regions by welding 48, 50. Here, a length compensation arrangement structure 44 with at least one length compensation element 46 is also provided in a manner preferably associated with each connecting element 32.

[0039] Another alternative design type is Figure 5As shown in the diagram. In this configuration, the length compensation element 46, which is configured to cooperate with the connecting element 32, for example, which is configured as a bolt, is constructed as an elastically deformable preload element, particularly as a disc spring. Due to its axial preload, the length compensation element 46 also holds the overlapping components of the exhaust heater 10—namely, the two support elements 20, 22, the heat conductors 14, 16, and the support units 38, 40, 42 disposed therebetween—in the case of thermally induced length changes in the connecting element 32. Especially when designed as a disc spring or wave spring constructed of metallic material, such a length compensation element 46 ensures that the preload force generated by this length compensation element is reliably maintained within the temperature range where the exhaust heater 10 experiences temperature changes.

[0040] Finally, it should be noted that the length compensation arrangement described above can vary in many different ways. As already mentioned, multiple length compensation elements can also be positioned at different axial locations in conjunction with one or more connecting elements. Alternatively or additionally, the length compensation element can also be positioned on the outer side of one or two support elements 20, away from the heat conductor, such that the length compensation element is positioned between the respective support element 20, 22 and the support area of ​​the connecting element, i.e., for example, the head 36 or the nut element 37. In such a design, the length compensation element 46 can also be constructed as an elastically deformable preload element that generates a preload force, i.e., constructed as a disc spring or wave spring, or it can be constructed from a material whose large coefficient of thermal expansion compensates for the relatively large absolute length variation of the connecting element 32.

Claims

1. An exhaust heater for an exhaust system of an internal combustion engine, the exhaust heater comprising: Support arrangement structure (24); A heat conductor arrangement structure (18) supported on the support arrangement structure (24) has at least one current-carrying heat conductor (14, 16), at least one heat conductor (14, 16) being electrically insulated about the support arrangement structure (24) by at least one support arrangement structure support unit (38, 40) or / and at least one heat conductor (14) being electrically insulated about another heat conductor (16) by at least one heat conductor support unit (42); A connection arrangement structure (31) for fixing the heat conductor arrangement structure (18) to the support arrangement structure (24), the connection arrangement structure (31) including at least one connection element (32). The feature is that it is provided with a length compensation arrangement structure (44) for compensating for different thermal expansion of the exhaust heater component, the length compensation arrangement structure (44) including at least one length compensation element (46) in the connection force transmission path between at least one connecting element (32) and the support arrangement structure (24) or / and the heat conductor arrangement structure (18).

2. The exhaust heater according to claim 1, characterized in that, The connection arrangement structure (31) includes at least one bolt-shaped connecting element (32).

3. The exhaust heater according to claim 1, characterized in that, The support arrangement structure (24) includes two successive support elements (20, 22) along the longitudinal axis (L) of the exhaust heater and between which the heat conductor arrangement structure (18) is accommodated, and the length compensation arrangement structure (44) includes at least one length compensation element (46) in a support path between at least one of the support elements (20, 22) and the heat conductor arrangement structure (18) or / and in a support path between two heat conductors (14, 16) of the heat conductor arrangement structure (18) or / and in a support path between at least one support element (20, 22) and at least one connection element (32) in a manner that is coupled with at least one connection element (32).

4. The exhaust heater according to claim 3, characterized in that, The length compensation arrangement structure (44) includes at least one length compensation element (46) in a manner that is coupled to each connecting element (32) in the support path between at least one of the support elements (20, 22) and the heat conductor arrangement structure (18) or / and in the support path between two heat conductors (14, 16) of the heat conductor arrangement structure (18) or / and in the support path between at least one support element (20, 22) and at least one connecting element (32).

5. The exhaust heater according to claim 3 or 4, characterized in that, At least one length compensation element (46) is disposed between the support element (20, 22) and the support element support unit (38, 40), or / and at least one length compensation element (46) is disposed between two heat conductors (14, 16), or / and at least one length compensation element (46) is disposed between the support element (20, 22) and the support area of ​​the connecting element (32) supported on the support element (20, 22).

6. The exhaust heater according to claim 3 or 4, characterized in that, Each length compensation element (46) is disposed between the support element (20, 22) and the support element support unit (38, 40), or / and each length compensation element (46) is disposed between two heat conductors (14, 16), or / and each length compensation element (46) is disposed between the support element (20, 22) and the support area of ​​the connecting element (32) supported on the support element (20, 22).

7. The exhaust heater according to any one of claims 1 to 4, characterized in that, At least one connecting element (32) passes through at least one length compensation element (46) and through at least one support element support unit (38, 40) and / or at least one thermal conductor support unit (42).

8. The exhaust heater according to claim 7, characterized in that, Each connecting element (32) extends through at least one length compensation element (46) and through at least one support element support unit (38, 40) and / or at least one thermal conductor support unit (42).

9. The exhaust heater according to any one of claims 1 to 4, characterized in that, At least one length compensation element (46) is constructed of a material having a larger coefficient of thermal expansion than the material of the at least one connecting element (32).

10. The exhaust heater according to claim 9, characterized in that, Each length compensation element (46) is constructed of a material having a larger coefficient of thermal expansion than the material of the at least one connecting element (32).

11. The exhaust heater according to claim 9, characterized in that, The at least one connecting element (32) is constructed of nickel-chromium alloy, and the at least one length compensation element (46) is constructed of steel.

12. The exhaust heater according to claim 11, characterized in that, The at least one length compensation element (46) constructed of steel is made of 1.4980 steel.

13. The exhaust heater according to any one of claims 1 to 4, characterized in that, At least one length compensation element (46) includes an elastically deformable preload element.

14. The exhaust heater according to claim 13, characterized in that, Each length compensation element (46) includes a preload element that can be elastically deformed.

15. The exhaust heater according to claim 13, characterized in that, At least one length compensation element (46) is constructed as a disc spring or a wave spring.

16. The exhaust heater according to claim 15, characterized in that, Each length compensation element (46) is constructed as a disc spring or a wave spring.

17. The exhaust heater according to any one of claims 1 to 4, characterized in that, The support arrangement (24) is constructed of metal, and / or the heat conductor arrangement (18) is constructed of metal.

18. An exhaust device for an internal combustion engine, said exhaust device comprising at least one exhaust heater (10) according to any one of claims 1 to 17.

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