Device for heating exhaust gas flow with tolerance compensation

Abstract

The invention relates to a device for heating an exhaust gas flow in an exhaust gas section, comprising: an electrically heatable heating base body (1); a support structure (3, 8) which is connected to the heating base body (1) by means of a plurality of support pins (2) and which can be mounted in a housing of an exhaust section, the heating base body (1) having a plurality of flow channels which can extend in a main flow direction from an end face forming an inflow side to an end face forming an outflow side, the support structure (3, 8) being formed in a grid-like manner, the support pins (2), which are located upstream and / or downstream of the heating base body (1), are inserted into the heating base body (1) and protrude from the inflow side and / or the outflow side, are integrally connected to the support structures (3, 8), the support structures (3) having solder reservoirs (6, 7, 9, 10) on the surface facing the heating base body (1), in which solder reservoirs the free ends (4, 5) of the respective support pins (2) are inserted.

Description

Field of the Invention

[0001] The present invention relates to a device for heating an exhaust gas flow in an exhaust section / exhaust passage, the device having: a heating matrix that can be electrically heated; a support structure that is connected to the heating matrix by a plurality of support pins, wherein the device can be installed in a housing of the exhaust section, wherein the heating matrix has a plurality of flow channels that can extend from an end face forming an inflow side to an end face forming an outflow side along a main flow direction, wherein the support structure is formed in a grid pattern and is located upstream and / or downstream of the heating matrix, and wherein the support pins inserted into the heating matrix and protruding from the inflow side and / or the outflow side are connected to the support structure in a material-locking manner. Background Art

[0002] In order to heat the exhaust gas in the exhaust section downstream of an internal combustion engine or to heat the exhaust gas flowing in the exhaust section, electric heating elements are nowadays commonly used. Here, the aim is to reach a temperature threshold more quickly, above which the harmful substances carried in the exhaust gas can be converted more effectively. This is necessary because the catalytically active surface of the catalytic converter installed in the exhaust section for exhaust gas aftertreatment can only achieve sufficient conversion of the corresponding harmful substances above a minimum temperature, i.e., the so-called light-off temperature.

[0003] Known solutions in the prior art include so-called heated catalytic converters, which have a metal structure connected to a voltage source or a ceramic structure with a metal coating that can be heated using ohmic resistance.

[0004] The heatable metal structure can, for example, include a honeycomb body made of metal foil. For this purpose, a plurality of smooth and / or at least partially structured metal foils are stacked together and wound around at least one pivot point to form a honeycomb body. The matrix formed by the metal foil can be electrically contacted and heated using ohmic resistance.

[0005] For this purpose, the matrix must be arranged in the exhaust section and be located upstream or downstream of the catalytic converter designed for exhaust gas aftertreatment in the flow direction of the exhaust gas.

[0006] In order to position and support the matrix in the exhaust section and in particular to resist mechanical and thermal loads, a bracket, i.e., a so-called support structure, must be provided. For this purpose, the support structure is designed to absorb and withstand the thermal cyclic loads and strong and irregular mechanical loads in the exhaust section. The support structure itself is fixed to the housing of the exhaust section.

[0007] In order to establish a material-locking connection between the heating substrate and the support structure, so-called support pins are used which are inserted into a chamber of the heating substrate and connected to the support structure. All components themselves have certain manufacturing tolerances. In addition, other tolerances can arise during the assembly process, so that the individual tolerances can accumulate into an unfavorable tolerance chain and result in an unacceptable overall tolerance which endangers the structural integrity of the components.

[0008] A disadvantage of the known solutions in the prior art is in particular that, although sometimes relatively high tolerances occur and the final position of the support pins relative to the support structure does not correspond to the actually planned position, there are currently no suitable means to reliably achieve the connection between the support pins and the support structure in a process-reliable manner. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide an improved device which enables a reliable connection between the support structure and the support pins to be achieved even under the influence of relatively large tolerances.

[0010] The object related to the device is achieved by a device having the features of claim 1.

[0011] An embodiment of the present invention relates to a device for heating an exhaust gas flow in an exhaust section, the device having: a heating substrate which can be electrically heated; a support structure which is connected to the heating substrate by a plurality of support pins, wherein the device can be installed in a housing of the exhaust section, wherein the heating substrate has a plurality of flow channels which can extend along a main flow direction from an end face forming an inlet side to an end face forming an outlet side, wherein the support structure is formed in a grid pattern and is located upstream and / or downstream of the heating substrate, wherein the support pins inserted into the heating substrate and protruding from the inlet side and / or the outlet side are connected to the support structure in a material-locking manner, and wherein the support structure has solder reservoirs on a surface facing the heating substrate, and the free ends of the respective support pins are inserted into these solder reservoirs (Lotreservoir).

[0012] During the manufacture of the individual components of the device, production-related tolerances which cannot be completely avoided occur. During assembly, the individual component tolerances can accumulate negatively, so that large tolerances occur as a result. In the case of the support pins, this can lead to different lengths of the support pins protruding from the heating substrate. Since the support structure is a substantially planar structure, not all of the support pins may abut against the support structure due to positional tolerances and component tolerances. This can prevent the formation of a durable material-locking connection between the support pins and the support structure. In extreme cases, defective connections or no connections may occur, which can lead to loose support pins. This affects the durability and stability of the device and, in the worst case, can lead to the destruction of the device.

[0013] According to the present invention, the support structure is configured with a plurality of solder storage portions, wherein a solder storage portion is correspondingly allocated for each support pin. The solder storage portion serves as a connection area between the support pin and the support structure.

[0014] Particularly preferably, the solder storage portion is formed by a recess in the support structure. The solder storage portion configured as a recess in the support structure can compensate for the positional tolerance of the support pin relative to the support structure. In an ideal design of the device, all support pins protrude from the heating substrate by the same length, such that the free ends of the support pins lie in the same common plane. In practice, the free ends of most support pins are slightly in front of or behind this common plane in a specific randomly distributed manner.

[0015] In order to obtain a sufficient connection between the support structure and the support pins, the support structure is positioned relative to the free ends of the support pins such that all support pins extend into the solder storage portion allocated for each support pin by a predetermined length. Therefore, the depth of the solder storage portion can be selected such that it is ensured that each support pin has a sufficient insertion depth in the solder storage portion, so that a brazed connection with sufficient strength can be produced.

[0016] Equally advantageously, the support pins extend into the solder storage portion. In the brazing process, a sufficient connection between the support pins and the support structure can only be produced by the free ends of the support pins extending into the solder storage portion. Due to the positional tolerance of the support pins, the corresponding free ends of the support pins are at different positions relative to the bottom of the corresponding solder storage portion of the support structure for each support pin. For a sufficient connection, it must be ensured that even for the support pin that is farthest from the bottom of the solder storage portion, a sufficient insertion depth is guaranteed.

[0017] The preferred embodiment is characterized in that the solder storage portion has a net opening width greater than the diameter of the support pin. By the net opening width of the solder storage portion being greater than the diameter of the free end of the support pin, in addition to compensating for the positional tolerance in the normal direction of the plane of the support structure, the tolerances in two spatial directions of the plane of the support structure can also be achieved. In the final assembled state, the free ends of the support pins do not have to be arranged precisely at the center of the solder storage portion, but can also be arranged offset from the solder pool.

[0018] Equally preferably, the solder storage portion is formed in the support structure by machining. Particularly advantageously, the solder storage portion is formed by a blind hole. In addition, it is advantageous that the solder storage portion is produced by a forming process on the support structure. The solder storage portion can be produced, for example, by stamping into the support structure.

[0019] Furthermore, it is advantageous that the solder storage is filled with solder paste and / or solder powder. The pre-filled solder storage can be easily melted during subsequent soldering processes in order to create a material-locking connection with the support pins joined into the solder storage.

[0020] Equally suitable is that at least a first quantity of support pins are placed on the bottom of their respective solder storage in the final assembled state. Depending on the relationship between the available insertion depth of the solder storage and the corresponding positional tolerances of the support pins, in the final assembled state, the free ends of a certain quantity of support pins directly abut the bottom area of the solder storage.

[0021] Advantageous refinements of the invention are described in the dependent claims and in the following description of the figures. Description of the Figures

[0022] The invention is explained in detail below with reference to the figures by way of examples. Among them:

[0023] Figure 1 A cross-sectional view of a heating substrate with inserted support pins is shown, wherein the support pins are joined into the solder storage of upstream and downstream support structures, and

[0024] Figure 2 Two cross-sectional views of support structures with solder storage of corresponding different designs are shown. Detailed Description of the Embodiment

[0025] Figure 1 A cross-sectional view of the heating substrate 1 is shown, from both sides of which the support pins 2 project. Support structures 3 are arranged upstream and downstream of the heating substrate 1. The respective free ends 4, 5 of the support pins 2 extend into the solder storage 6, 7 constructed in the support structures 3. By means of the soldering process, the soldering material filled into the solder storage 6, 7 melts and a lasting connection is established with the support pins 2 and the support structures 3 extending into the solder storage 6, 7.

[0026] Figure 2 A cross-sectional view of the support structure 8 is shown, wherein on the left-hand part of the figure the solder storage 9 produced by machining is shown. On Figure 2 the right-hand part, the solder storage 10 produced by shaping, for example stamping, is shown.

[0027] Figures 1 to 2 The embodiments of... are not restrictive features in particular, but are only used to illustrate the concept of the invention.

[0028] List of Reference Numerals:

[0029] 1 Heating substrate

[0030] 2 Support pin

[0031] 3 Support structure

[0032] 4 Free end of the support pin

[0033] 5 Free end of the support pin

[0034] 6 Solder storage part

[0035] 7 Solder storage part

[0036] 8 Support structure

[0037] 9 Solder storage part

[0038] 10 Solder storage part

Claims

1. A device for heating an exhaust gas flow in an exhaust section, the device having: a heating matrix (1) that can be electrically heated; a support structure (3, 8) that is connected to the heating matrix (1) by a plurality of support pins (2), wherein, The device can be installed in the housing of the exhaust section. Among them, the heating matrix (1) has a plurality of flow channels, and these flow channels can extend from the end face forming the inflow side to the end face forming the outflow side along the main flow direction. Among them, the support structures (3, 8) are formed in a grid pattern, upstream and / or downstream of the heating matrix (1). Among them, the support pins (2) inserted into the heating matrix (1) and protruding from the inflow side and / or the outflow side are connected to the support structures (3, 8) in a material-locking manner. It is characterized in that the support structure (3) has solder storage parts (6, 7, 9, 10) on the surface facing the heating matrix (1), and the free ends (4, 5) of the respective support pins (2) are inserted into the solder storage parts.

2. The device according to claim 1, characterized in that The solder storage parts (6, 7, 9, 10) are formed by recesses in the support structures (3, 8).

3. The device according to any one of the preceding claims, characterized in that, The support pins (2) extend into the solder storage parts (6, 7, 9, 10).

4. The device according to any one of the above claims, characterized in that, The solder storage parts (6, 7, 9, 10) have a net opening width larger than the diameter of the support pins (2).

5. The device according to any one of the above claims, characterized in that, The solder storage part (9) is formed in the support structure (8) by a machining method.

6. The device according to any one of the above claims, characterized in that, The solder storage part (10) is produced by a forming process on the support structure (8).

7. The device according to any one of the above claims, characterized in that The solder storage parts (6, 7, 9, 10) are filled with solder paste and / or solder powder.

8. The device according to any one of the above claims, characterized in that At least a first number of support pins (2) are placed on the bottom of their respective solder storage parts (6, 7, 9, 10) in the final assembled state.

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