JP2005076538A - Exhaust manifold with built-in filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust manifold with a built-in filter, having simple, light and versatile construction permitting stable self-regeneration of the filter using exhaust gas. <P>SOLUTION: The exhaust manifold has a double tube structure with inner tubes 11, 12 and an outer tube 13 between which cavities exist. Near an exhaust inlet portion 14a of a fastening flange 14 of the exhaust manifold, a cylindrical filter case 21 embracing a particulate filter 22 is provided to be almost all housed in the outer tube 13. The filter case has an inlet end 21a connected and fixed to the exhaust inlet portion 14a and an outlet end 21b onto which the inner tubes 11, 12 are externally fitted and mounted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust manifold with a built-in filter. In particular, the present invention relates to an exhaust manifold having a double pipe structure in which a particulate filter is provided at an exhaust inlet portion.

  In general, exhaust gas discharged from a diesel engine contains particulates (particulate matter) that cause air pollution, and various devices for removing and purifying this have been proposed. For example, in the exhaust gas purification device of Patent Document 1, an electric heater (auxiliary heat source) is incorporated in a filter unit that collects particulates, and the collected particulates are burned by the electric heater to regenerate the filter. Further, in the exhaust purification device of Patent Document 2, a cylindrical member is interposed between each exhaust port of the engine cylinder head and the exhaust manifold, and a trap filter is accommodated in each cylindrical member. Then, the particulates collected by each trap filter are heated and burned with exhaust gas immediately after being discharged from the engine to regenerate the trap filter.

  However, since the device of Patent Document 1 requires an electric heater as an auxiliary heat source, not only the device structure is large and the in-vehicle property is poor, but also there is difficulty in controlling the auxiliary heat source, and the range of use of the technology is limited. On the other hand, in the apparatus of Patent Document 2, since the cylindrical member that houses the trap filter is interposed between the engine cylinder head and the exhaust manifold, the cylindrical member is exposed to the outside. For this reason, the exhaust gas passing through the trap filter is likely to be cooled due to insufficient heat insulation, and this tends to hinder the regeneration of the trap filter using the exhaust gas.

JP 11-182232 A (summary) Japanese Utility Model Publication No. 5-69311 (full text description)

  An object of the present invention is to provide an exhaust manifold with a built-in filter that is simple in structure and light in weight, excellent in versatility, and capable of stably performing self-regeneration of a filter using exhaust gas.

  According to a first aspect of the present invention, there is provided an exhaust manifold having a double pipe structure having an exhaust inlet portion corresponding to an exhaust port of an engine and having an inner pipe and an outer pipe and securing a gap between the inner and outer pipes. A cylindrical filter case containing a particulate filter is provided in the vicinity of the exhaust inlet of the manifold so that it is almost housed inside the outer tube, and the inlet end of the filter case is connected and fixed to the exhaust inlet. In addition, an exhaust manifold with a built-in filter is characterized in that the inner pipe is fitted to the outlet end of the filter case by fitting.

  According to the first aspect of the present invention, the filter case containing the particulate filter is disposed inside the outer pipe of the exhaust manifold having a double pipe structure and is not directly exposed to the outside air. Yes. In addition, the filter case has an inlet end that is in contact with the exhaust inlet portion by connecting and fixing, and an outlet end is only in contact with the manifold inner tube by fitting, so that the area where the filter case contacts the exhaust manifold. (Contact cross-sectional area) is small, and heat conduction from the filter (particulate filter and filter case) to the exhaust manifold body is small. Due to the synergistic effect of these circumstances, the temperature reduction of the exhaust gas passing through the filter is suppressed as compared with the conventional example, and the self-regeneration of the filter using the exhaust gas can be stably performed.

  According to a second aspect of the present invention, in the exhaust manifold with a built-in filter according to the first aspect, an inlet end of the inner pipe is attached to an outlet end of the filter case by an external fitting.

  According to claim 2, since the inlet end of the exhaust manifold inner pipe is only fitted by external fitting with respect to the outlet end of the filter case, there is room for the filter to thermally expand in the axial direction by the heat of the exhaust gas, At least the inner tube does not hinder the axial thermal expansion of the filter. Therefore, the degree of freedom of thermal expansion is ensured in the filter, and stress concentration on the filter is avoided. For this reason, damage to the filter due to thermal stress concentration can be prevented, and durability reliability can be improved.

  According to a third aspect of the present invention, in the exhaust manifold with a built-in filter according to the first or second aspect, an exhaust inlet portion of the exhaust manifold is formed on a fastening flange provided for fastening the exhaust manifold to the engine. It is characterized by being.

  According to the third aspect, since the inlet end of the cylindrical filter case is connected and fixed to the exhaust inlet portion formed in the fastening flange, the filter case and the particulate filter contained therein are mainly used as the fastening flange. Supported by When mounted on an actual vehicle, the fastening flange is fastened to the engine (more specifically, the cylinder head of the engine), so that the inner pipe and the outer pipe of the exhaust manifold may directly bear the load of the filter case and the particulate filter. And the support of the filter is stable.

  As described above, according to the exhaust manifold with a built-in filter of the present invention, a cylindrical filter case containing a particulate filter is provided in the vicinity of the exhaust inlet of the exhaust manifold so as to be substantially accommodated inside the outer pipe, Since the filter case has a simple, lightweight and highly versatile structure that minimizes the area (contact cross-sectional area) that contacts the exhaust manifold, it can suppress the temperature drop of the exhaust gas that passes through the filter. It is possible to stably perform self-regeneration of the filter using gas. Further, by fitting the inner tube to the outlet end of the filter case, it is possible to ensure the degree of freedom of thermal expansion of the filter and prevent the filter from being damaged due to thermal stress concentration.

  Hereinafter, an embodiment in which the present invention is embodied in an exhaust manifold for a four-cylinder diesel engine will be described with reference to the drawings.

  As shown in FIG. 1, the exhaust manifold includes a first inner pipe 11, a second inner pipe 12, an outer pipe 13, an upstream flange 14 and a downstream flange 15. These manifold components (11-15) are made of stainless steel, for example. The first and second inner pipes 11 and 12 are accommodated in the outer pipe 13, and a predetermined gap (air gap) is ensured between the inner pipes 11 and 12 and the outer pipe 13. The exhaust manifold has a double pipe structure. The first and second inner tubes 11 and 12 are fitted and connected at a substantially central position in the longitudinal direction of the outer tube 13, and an annular buffer member 17 surrounds the connecting portion of the two inner tubes 11 and 12. Thus, one end of each of the inner pipes 11 and 12 is supported in the outer pipe 13. The first inner pipe 11 guides exhaust gas discharged from the exhaust ports P1, P2 of the right two cylinders of the engine, and the second inner pipe 12 is discharged from the exhaust ports P3, P4 of the left two cylinders of the engine. The exhaust gas and the exhaust gas from the first inner pipe 11 are guided to the manifold outlet 16 provided in the downstream flange 15.

  The upstream flange 14 of the exhaust manifold is a long plate-like member extending along the longitudinal direction of the outer tube 13, and plays a role as a fastening flange for fastening the exhaust manifold to a cylinder head of a four-cylinder engine. . On the other hand, the downstream flange 15 of the exhaust manifold is provided to connect the manifold outlet 16 to an inlet portion of, for example, a catalytic converter disposed on the downstream side thereof.

  As shown in FIG. 2, the upstream flange 14 is formed with four circular openings 14a as through exhaust openings corresponding to the four exhaust ports P1 to P4 of the engine. Each of the four inlet ends 13a of the outer tube 13 is fitted and arranged in each of the circular openings 14a of the upstream flange, and the inner peripheral surface of each circular opening 14a and the outer periphery of each outer tube inlet end 13a. The upstream flange 14 and the outer tube 13 are interconnected by performing all-around welding on the overlapping portion with the surface.

  A cylindrical filter case 21 is provided in the vicinity of the circular opening 14 a of the upstream flange so as to be accommodated inside the outer tube 13. That is, the inlet end 21a of each filter case 21 is inward of each circular opening 14a (more specifically, further inside each inlet end 13a of the outer pipe welded to the inner side of each circular opening 14a). Thus, each filter case 21 is supported and fixed in the exhaust manifold by being connected by all-around welding. A cylindrical particulate filter 22 having an outer diameter substantially corresponding to the inner diameter of the filter case 21 is held inside each filter case 21. The particulate filter 22 is integrated with the filter case 21 by brazing or the like. The particulate filter 22 is formed by partitioning a number of cells extending in the axial direction by a number of partition walls made of, for example, a porous ceramic material.

  As shown in FIG. 2, the inlet ends of the first and second inner pipes 11 and 12 are fitted around the outlet end 21 b of each filter case 21. Since the outlet end 21b of each filter case and the inlet ends of the inner pipes 11 and 12 are simply fitted, the filter case 21 and the inner pipe 11 (or 12) restrain relative movement in the axial direction. They are fitted in a state where there is room for one to shift axially with respect to the other. Based on such external fitting, the first and second inner pipes 11 and 12 are mounted on the four filter cases 21 that are fixed to the upstream flange 14. That is, the first and second inner pipes 11 and 12 are surrounded by the fitting portion with the two filter case outlet ends 21 b corresponding to the two inlet ends of the respective inner pipes and the annular buffer member 17. Further, it is stably held in the outer tube 13 by being supported at at least three locations of the connecting portion with the other inner tube.

  According to the configuration shown in FIGS. 1 and 2, the hot exhaust gas discharged from the engine flows into the exhaust manifold via the exhaust ports P1 to P4 of the cylinder head. At that time, the exhaust gas passes through the particulate filter 22, is led into the inner pipes 11 and 12 of the exhaust manifold, and is further led to the manifold outlet 16.

  According to the present embodiment, the filter case 21 is disposed in the outer pipe 13 of the exhaust manifold and is not directly exposed to the outside air, so that the heat insulating property of the particulate filter 22 is excellent. In addition, the filter case 21 has an inlet end 21a connected to the upstream flange 14 and an outlet end 21b fitted and in contact with the inlet ends of the inner pipes 11 and 12, so that the filter case 21 is connected to the exhaust manifold. The contact area (contact cross-sectional area) is small, and heat conduction from the particulate filter 22 and the filter case 21 to the exhaust manifold body is small. Therefore, the temperature drop of the exhaust gas passing through the filter 22 is suppressed, and the self-regeneration of the filter 22 using the exhaust gas can be stably performed.

  According to the present embodiment, since the inlet ends of the inner pipes 11 and 12 are only fitted by external fitting with respect to the outlet end 21b of the filter case, the particulate filter 22 (and the filter case 21) is caused by the heat of the exhaust gas. There is room for thermal expansion in the axial direction, and the inner tubes 11 and 12 do not hinder the axial thermal expansion of the filter 22 (and the filter case 21). Therefore, the degree of freedom of thermal expansion is secured in the filter 22 (and the filter case 21), and stress concentration on the filter 22 is avoided. For this reason, breakage of the filter 22 can be prevented and durability reliability can be improved. The exhaust manifold with a built-in filter according to the present embodiment has a simple structure and is lightweight, and has excellent versatility.

  (Modification) The embodiment of the present invention may be modified as follows. In the above embodiment, the two inner pipes 11 and 12 are provided in the single outer pipe 13, but the two inner pipes 11 and 12 may be integrated into a single inner pipe. Further, in FIG. 2, an arrangement structure is employed in which the inlet end 13a of the outer tube is sandwiched between the inner peripheral surface of the circular opening 14a of the upstream flange and the outer peripheral surface of the inlet end 21a of the filter case. The outer peripheral surface of the inlet end 21a of the filter case may be directly connected to the inner peripheral surface of the circular opening 14a of the upstream flange without sandwiching the inlet end 13a of the outer tube.

The top view which shows the whole outline | summary of an exhaust manifold. Sectional drawing in the AA of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... 1st inner pipe, 12 ... 2nd inner pipe, 13 ... Outer pipe, 13a ... Inlet end of outer pipe, 14 ... Upstream flange (fastening flange), 14a ... Circular opening part (exhaust inlet part), DESCRIPTION OF SYMBOLS 15 ... Downstream flange, 21 ... Filter case, 21a ... Inlet end of filter case, 21b ... Outlet end of filter case, 22 ... Particulate filter, P1, P2, P3, P4 ... Exhaust port of engine

Claims (3)

In an exhaust manifold having a double pipe structure having an exhaust inlet corresponding to an exhaust port of an engine, an inner pipe and an outer pipe, and securing a gap between the inner and outer pipes,
In the vicinity of the exhaust inlet of the exhaust manifold, a cylindrical filter case containing a particulate filter is provided so as to be almost accommodated in the outer pipe, and the inlet end of the filter case is connected to the exhaust inlet. An exhaust manifold with a built-in filter, wherein the inner pipe is fixedly fitted to the outlet end of the filter case by fitting.   The exhaust manifold according to claim 1, wherein an inlet end of the inner pipe is attached to an outlet end of the filter case by external fitting.   The exhaust manifold with a built-in filter according to claim 1 or 2, wherein an exhaust inlet portion of the exhaust manifold is formed on a fastening flange provided for fastening the exhaust manifold to the engine.

Images