Exhaust gas heating element

Abstract

Exhaust gas heating element (1) comprising a substantially cylindrical plate (2) with axis (A) and with a circular, elliptical or rectangular cross-section (S) with rounded corners made of metal foam, extending perpendicular to axis (A) of a large dimension (D) and along axis (A) of a thickness (E), a flexible, electrically insulating film (3) covering an edge of the plate (2) with an overlap (R) on each side, a rigid, substantially cylindrical connecting ring (4) with the same cross-section (S) covering the edge of the plate (2) with an overlap (R) on each side of the same cross-section (S) and covering the film (3) with an overlap (R) on each side, a substantially cylindrical housing (5) with axis (A) and the same cross-section (S) that can accommodate the ring (4) and two electrodes (6, 7), characterized in that the ring (4) is formed from a large truncated cylinder (D),in which at least a first edge is toothed in such a way that the plate (2) and the foil (3) can be fixed in the ring (4) by folding the teeth (T) essentially by 90°.

Description

Technical field

[0001] The invention relates to an exhaust gas heating element of the type with a metal foam plate that can be heated by the Joule effect. State of the art

[0002] It is known to use a metal foam plate to heat an exhaust gas flowing in a pipe that is usually located at the outlet of an internal combustion engine.

[0003] The plate is arranged transversely to the pipe in which the exhaust gas flows, with the axis of the plate coinciding with the axis of the pipe.

[0004] The porosity of the metal foam allows the exhaust gas to flow through the plate. The metal foam forms the substrate, which is heated by the Joule effect via at least two electrodes, so that its heat is transferred to the exhaust gas flowing through the plate.

[0005] However, the metal foam alone lacks mechanical strength and must be reinforced. Furthermore, in order to apply an electric current to the metal foam plate via electrodes, the plate must be electrically insulated from the conductor, which is usually made of metal.

[0006] US 5,463,206 A and US 6,423,276 B1 describe examples of known exhaust gas heating elements.

[0007] The object of the present invention is to provide an exhaust gas heating element with which the functions of stiffening and electrical insulation are achieved. Summary of the invention

[0008] This problem is solved by an exhaust gas heating element comprising a substantially cylindrical plate with a circular, elliptical or rectangular cross-section with rounded corners, made of metal foam, extending perpendicular to the axis of a large dimension and along the axis of a thickness, a compliant, electrically insulating film covering an edge of the plate with an overlap on each side, a rigid connecting ring of the same cross-section, which is substantially cylindrical along the axis and covers the film with an overlap on each side, and a substantially cylindrical housing with the axis and the same cross-section, which can accommodate the ring and two electrodes, wherein the ring is formed from a truncated cylinder of large dimensions, in which at least a first edge is toothed such that the plate and the film can be fixed in the ring by folding the teeth substantially by 90°.

[0009] Special features or embodiments, which can be used individually or in combination, include the following: - a second edge of the ring is toothed in such a way that the plate and the foil can be fixed in the ring by folding the teeth over at an angle of essentially 90°, - the second edge of the ring is essentially spaced from the first edge of the ring by the thickness plus two overlaps, - a second edge of the ring is stamped out in such a way that it has a reduction in size similar to that obtained by folding over the teeth, where a small dimension is equal to the large dimension of the plate minus two overlaps, - the teeth have a length that essentially corresponds to the overlap, - a sheet has the shape of a truncated cylinder, the dimension of which is essentially equal to the large dimension and which is essentially identical to the ring, each of the edges being symmetrically toothed such that the plate can be enclosed by folding the teeth substantially by 90°, the teeth having a length that is essentially equal to the overlap, - a foil has the shape of a flat crown, with an inner dimension essentially equal to the small dimension, an outer dimension essentially equal to the inner dimension plus twice the thickness of the plate and four overlaps, wherein the outer dimension is toothed such that the plate can be enclosed by folding the teeth substantially twice by 90°, wherein the teeth have a length essentially equal to the thickness plus one overlap, - the number of teeth is between 2 and 50, preferably between 4 and 40 and further preferably between 10 and 30, - the teeth are folded with a radius between 0.1 and 5 mm, preferably between 0.2 and 2 mm, - the overlap is between 5 and 20 mm, preferably between 8 and 15 mm and more preferably 11 mm. Brief description of the drawings

[0010] The invention will be better understood by reading the following description, which is only exemplary and refers to the accompanying figures. These figures show: Fig. 1 a heating element in a perspective exploded view, Fig. 2 a subassembly with a ring, a foil and a plate in a perspective view, Fig. 3 a subassembly according to a first embodiment in a perspective view, Fig. 4 a ring according to a further embodiment in a perspective view, Fig. 5 a film according to a further embodiment, Fig. 6 a subassembly according to a further embodiment in a perspective view. Description of the embodiments

[0011] With reference to Fig. Figure 1 shows a heating element 1 for exhaust gas in a perspective exploded view. This heating element 1 has a plate 2. This plate 2, made of metal foam, is essentially cylindrical with an axis A, where the axis A coincides with the axis of the exhaust pipe.

[0012] Here and throughout this document, a cylinder is understood to be a general cylinder, i.e., a volume described by the displacement of any cross-section S along an axis A.

[0013] The exhaust gas flow is essentially parallel to direction A.

[0014] The plate 2 has a cross-section S, which is preferably circular, elliptical, or rectangular with rounded corners. Furthermore, its principal extent runs perpendicular to the axis A along a large dimension D. This large dimension D generally defines the extent of the plate 2. For an elliptical cross-section, this large dimension D is determined successively by the minor or major axis of the ellipse. For a circular cross-section, this large dimension D is determined by the diameter. For a rectangular cross-section, this large dimension D is determined successively by the minor or major side.

[0015] The extent of plate 2 along axis A is called thickness E.

[0016] To provide electrical insulation around the plate 2, an insulating film 3 covers the plate 2 at the points that can come into contact with metal parts, namely at the edge of the plate 2. To ensure an insulating edge, the film 3 is extended by at least one overlap R on each side of the plate 2. The film 3 is made of a flexible textile material and can be shaped by folding. The thickness of the film 3 is so small that it is negligible. The dimensions of the film 3 arranged around the plate 2 correspond essentially to the dimensions of the plate 2, i.e., it is a general cylinder with the large dimension D, cross-sectional area S, and thickness E.

[0017] A rigid connecting ring 4 surrounds the assembly of plate 2 and foil 3 to fix and hold the foil 3 in position and simultaneously stiffen the subassembly of ring 4, foil 3, and plate 2. This ring 4 is made of sheet metal. The thickness of the sheet metal is small. The dimensions of the ring 4 arranged around the foil 3 and the plate 2 correspond essentially to the dimensions of the plate 2, namely a general cylinder with the large dimension D, the cross-section S, and the thickness E.

[0018] The shape of ring 4 is essentially identical to that of foil 3, so that it essentially covers the latter. Ring 4 has a similar cross-section S to foil 2, covers foil 2 at its edge, and has an overlap R on each of its sides with foil 2.

[0019] The assembly, consisting of a plate 2, a foil 3, and a ring 4, is then arranged in a housing 5, which is located in the exhaust pipe. The latter is essentially cylindrical with axis A and the same cross-section S as the plate 2.

[0020] The assembly is supplemented by two electrodes 6, 7. The electrodes 6, 7 are preferably arranged radially in openings 8 of the housing 5. These openings 8 correspond to openings 8' in the ring and openings 8'' in the foil 3, so that the electrodes 6, 7 can bring the electric current into contact with the plate 2 for heating it.

[0021] The invention relates to the embodiment of ring 4 in such a way that a sub-assembly, as in Fig. 2 is shown, formed, which includes a ring 4 that clamps a foil 3 around a plate 2.

[0022] According to a first characteristic, which is particularly in Fig. As illustrated in Figure 3, the ring 4 is made from a truncated cylinder, here again a general cylinder with the same cross-section S as the plate 2 with the large dimension D.

[0023] According to an advantageous feature, at least one first edge of this truncated cylinder is toothed. By folding the teeth T essentially by 90°, it is thus possible to form a stop with which the plate 2 and the foil 3 can be fixed in the ring 4. As in Fig. As illustrated in Figure 2, a ring 4 is formed by folding over the teeth T of the upper edge.

[0024] According to the in Fig. In the embodiment shown in Figure 3, the ring 4 has a further, second edge, which is also toothed. According to this embodiment, the ring 4 is thus symmetrical, and the two edges make it possible to form two axial stops, an upper and a lower stop, which are suitable for fixing the plate 2 and the film 3 in the ring 4 by folding the teeth T essentially by 90°.

[0025] To be like in Fig. As shown in Figure 3, to clamp a plate 2 and a foil 3, the height of the truncated cylinder can cover the edge of the plate 2. This height also corresponds to the thickness E of the plate 2. Furthermore, this height is extended upwards and downwards by a series of teeth T. The height of one tooth T corresponds to one overlap R. Thus, the height of the ring 4 before the teeth T are folded over essentially corresponds to the thickness E of the plate 2 plus two overlaps R.

[0026] According to a further embodiment, which is particularly found in the Fig. 4, Fig. 5 to Fig. As illustrated in Figure 6, the second edge of ring 4 is produced by punching. As shown in Figure 6. Fig. As shown in Figure 4, the aim of the punching process is to form a stop with a reduction in dimensions similar to that obtained by folding over the teeth T. This stop has a small dimension d, which corresponds to the large dimension D of plate 2 minus two overlaps R.

[0027] This embodiment produces a shape that is essentially identical to that obtained by folding over the teeth T of a toothed edge. However, it advantageously has better stiffness than its toothed counterpart.

[0028] However, only a single edge can be produced by die-cutting.

[0029] In both embodiments, at least one edge must be toothed to allow the arrangement of the plate 2 and the foil, with the teeth T enabling closure after arrangement.

[0030] According to another feature, the teeth T, both the teeth of ring 4 and the teeth of foil 3, have a length that essentially corresponds to the desired overlap R.

[0031] The foil 3 can be manufactured in at least two embodiments, independent of the embodiment of the ring 4.

[0032] According to another characteristic, which is particularly in Fig. As shown in Figure 3, a sheet 3 is cut in a pattern similar to that of the ring 4 of the first embodiment, i.e., a pattern in the shape of a truncated cylinder with a dimension substantially equal to the large dimension D, wherein each of the edges is symmetrically toothed such that the plate 2 can be enclosed by folding the teeth T substantially by 90°. In this case, the teeth T have a length substantially equal to the overlap R.

[0033] It should be noted that such a foil 3 for a ring 4 according to the first embodiment, in Fig. 3 illustrated, and furthermore for a ring 4 according to the second embodiment, in Fig. 4 illustrates, suitable.

[0034] According to another characteristic, a film can be in a format such as in Fig.The cut pattern shown in Figure 5 is used. A sheet 3 then has the shape of a flat crown. The inner cutout has an inner dimension that is essentially equal to the small dimension d, i.e., dimension D minus two overlaps R. The outer dimension is essentially equal to the inner dimension plus twice the thickness E of the sheet 2 and four overlaps R. Furthermore, the outer contour is toothed such that the sheet 2 can be enclosed by folding the teeth T essentially twice by 90°. The plane of the sheet 3 coincides here with one side of the sheet 2. The teeth T must also be folded once to cover the edge of the sheet 2 and a second time to cover the opposite side of the sheet 2. The teeth T must also have a greater length compared to the other embodiment, i.e., a length that is essentially equal to the thickness E plus one overlap R.

[0035] According to another feature, the number of teeth is between 2 and 50, preferably between 4 and 40, and more preferably 26.

[0036] According to a further feature, the teeth T are folded according to a folding radius that is between 0.1 and 5 mm, preferably between 0.2 and 2 mm. This applies to both the teeth T of the foil 3 and the teeth T of the ring 4.

[0037] According to a further feature, the overlap R is between 5 and 20 mm, preferably between 8 and 15 mm and more preferably 11 mm.

[0038] The invention is illustrated and described in detail in the drawings and the preceding description. This description is to be understood as illustrative and exemplary, and not as limiting the invention solely to this description. Numerous embodiments are possible. Reference symbol list 1 heating element, 2 tiles, 3 insulating foil, 4 connecting rings, 5 cases, 6, 7 electrode, 8, 8', 8" opening, Axis A D large dimension, d small dimensions, E thickness R Overlap, S cross-section, T tooth

Claims

Exhaust gas heating element (1) comprising a substantially cylindrical plate (2) with axis (A) and with a circular, elliptical or rectangular cross-section (S) with rounded corners made of metal foam, extending perpendicular to the axis (A) of a large dimension (D) and along the axis (A) of a thickness (E), a compliant, electrically insulating film (3) covering an edge of the plate (2) with an overlap (R) on each side, a rigid, substantially cylindrical connecting ring (4) with the same cross-section (S) covering the edge of the plate (2) with an overlap (R) on each side of the same cross-section (S) and covering the film (3) with an overlap (R) on each side, a substantially cylindrical housing (5) with axis (A) and the same cross-section (S) that can accommodate the ring (4) and two electrodes (6, 7), characterized in that the ring (4) is formed from a large truncated cylinder (D),in which at least a first edge is toothed in such a way that the plate (2) and the foil (3) can be fixed in the ring (4) by folding the teeth (T) essentially by 90°. Heating element (1) according to claim 1, wherein a second edge of the ring (4) is toothed such that the plate (2) and the foil (3) can be fixed in the ring (4) by folding the teeth (T) substantially by 90°. Heating element (1) according to claim 2, wherein the second edge of the ring (4) is spaced substantially apart from the first edge of the ring (4) by the thickness (E) plus two overlaps (R). Heating element (1) according to claim 1, wherein a second edge of the ring (4) is stamped such that it has a diameter reduction similar to that obtained by folding over the teeth, wherein a small dimension (d) is equal to the large dimension (D) of the plate (2) minus two overlaps (R). Heating element (1) according to one of the preceding claims, wherein the teeth (T) have a length which substantially corresponds to the overlap (R). Heating element (1) according to one of claims 1 to 5, wherein a film (3) has the shape of a truncated cylinder whose dimensions correspond substantially to the large dimension (D) and which is substantially identical to the ring (4), wherein each of the edges is symmetrically toothed such that the plate (2) can be enclosed by folding the teeth (T) substantially by 90°, wherein the teeth (T) have a length that substantially corresponds to the overlap (R). Heating element (1) according to one of claims 1 to 5, wherein a foil (3) has the shape of a flat crown, with an inner dimension that is essentially equal to the small dimension (d), an outer dimension that is essentially equal to the inner dimension plus twice the thickness (E) of the plate (2) and four overlaps (R), wherein the outer dimension is toothed such that the plate (2) can be enclosed by folding the teeth (T) substantially twice by 90°, wherein the teeth (T) have a length that is essentially equal to the thickness (E) plus one overlap (R). Heating element (1) according to one of the preceding claims, wherein the number of teeth (T) is between 2 and 50. Heating element (1) according to one of the preceding claims, wherein the teeth (T) are folded with a radius between 0.1 and 5 mm. Heating element (1) according to one of the preceding claims, wherein the overlap (R) is between 5 and 20 mm.

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