JP5685294B2 - Exhaust gas purification device - Google Patents

Description

  The present invention relates to an exhaust gas purification device mounted on a diesel engine or the like, and more particularly to an exhaust gas purification device that removes particulate matter (soot, particulates) and the like contained in exhaust gas. .

  Conventionally, a diesel particulate filter (hereinafter referred to as DPF) is provided as an exhaust gas purification device (post-treatment device) in the exhaust path of a diesel engine, and the exhaust gas discharged from the diesel engine is purified by the DPF. Is known (see, for example, Patent Document 1).

  In addition, a technique for providing a temperature sensor for detecting the temperature of exhaust gas discharged from a diesel engine and a pressure sensor for detecting the pressure of exhaust gas discharged from a diesel engine in the DPF is also known (for example, Patent Documents 1 to 3). 2).

  Further, in the DPF, a technique is known in which an inner case is provided in a double structure inside an outer case, and an oxidation catalyst or a soot filter is provided in the inner case (see, for example, Patent Document 3).

  Further, in the DPF, a technique is also known in which a case in which an oxidation catalyst is placed and a case in which a soot filter is placed are detachably connected via a flange fastened by a bolt (see, for example, Patent Documents 4 to 5). .

JP 2004-263593 A JP 2001-73748 A JP 2005-194949 A JP 2009-228516 A JP 2009-91982 A

  In the prior art, an exhaust gas that detects the temperature of exhaust gas discharged from a diesel engine in a structure that connects a single structure case in which an oxidation catalyst is installed and a single structure case in which a soot filter is installed. When a temperature sensor or an exhaust gas pressure sensor that detects the pressure of exhaust gas is provided, the exhaust gas temperature sensor support part and the exhaust gas extraction part for pressure detection are disposed between the oxidation catalyst and the soot filter. By forming it in a case having a structure, the exhaust gas temperature inside the case tends to decrease, and the outer surface of the case tends to become high temperature.

  That is, when the exhaust gas temperature inside the case is lowered, particulate matter in the exhaust gas is likely to be clogged in the soot filter, and it is necessary to regenerate the soot filter at a high frequency, and the exhaust gas purification performance cannot be improved. There are problems such as. On the other hand, since the case outer surface becomes high temperature, it is necessary to perform maintenance of the diesel engine after the case is cooled, and there is a problem that handling workability cannot be improved.

  Therefore, the present invention seeks to provide an exhaust gas purifying apparatus that has been improved by examining these current conditions.

The present invention includes a plurality of gas purification bodies for purifying exhaust gas discharged from the engine, a plurality of inner cases for installing the gas purification bodies, and a plurality of outer cases for installing the inner cases. In the exhaust gas purifying apparatus, the flange body of one of the outer cases and the flange body of the other outer case are abutted and connected to each other, and the inner surface of one inner case is connected to the inner surface of the other inner case. A heat shield case extended to the outer surface of the case is provided, and the other inner case is inserted into the heat shield case, while the heat shield case is disposed on the outer peripheral surface on the inner side of the end surface of the one inner case. One end side is fixed, and the other end side of the heat shield case is connected to the flange body of one of the outer cases, and an exhaust gas sensor support sensor is provided on the outer peripheral surface of the heat shield case. With fixing the scan body, it is obtained by extending the sensor boss body laterally outward of the outer casing.

According to the present invention, an exhaust gas comprising a plurality of gas purification bodies for purifying exhaust gas discharged from an engine, a plurality of inner cases in which the gas purification bodies are installed, and an outer case in which the inner cases are installed. In the gas purification apparatus, the flange body for joining the outer case is connected to the other end side of the heat shield case extended from one inner case to the outer surface of the other inner case. It is possible to easily prevent the exhaust gas from leaking from the purifier to the outer case. And the fall of the exhaust gas temperature of a gas purification body, the raise of the surface temperature of an outer case, etc. can be reduced by the heat insulation effect | action of an outer case and a heat insulation case. By maintaining the exhaust gas temperature inside the inner case, particulate matter in the exhaust gas can be reduced from staying inside the gas purifier (soot filter), and the gas purifier is regenerated at a high frequency. There is no need to improve the exhaust gas purification performance. On the other hand, since an increase in the outer surface temperature of the outer case is suppressed, maintenance of the engine can be performed before the engine or the like is cooled, and handling workability can be improved.

According to the present invention, a heat shielding case is provided on the outer surface of one inner case, and the other inner case is inserted into the heat shielding case, while the outer peripheral surface is located on the inner side of the end surface of the one inner case. Since one end side of the heat shield case is fixed, the outer case and the heat shield case can be extended to a portion where the gas purifiers face each other. The exhaust gas temperature can be easily maintained. In addition, while the inner cases can be formed to have the same diameter, the opposing spacing of the gas purifiers can be formed to the shortest dimension. As a result, the total length of the DPF can be shortened, and the DPF can be easily mounted on various devices. The exhaust gas sensor can be brought close to the end face of the gas purifying body, and control performance such as automatic regeneration of the DPF can be improved.

  In the present invention, the outlet end portion of the inner case on the upstream side of the exhaust gas and the inlet end portion of the inner case on the downstream side of the exhaust gas are overlapped to form a double structure, and the exhaust gas is exhausted on the outlet end portion of the dual structure or the outer surface of the inlet end portion By arranging a sensor boss body for supporting the gas sensor and extending the sensor boss body to the outside of the outer case, an exhaust gas temperature sensor and an exhaust gas pressure sensor pipe can be easily assembled via the sensor boss body. Can be attached. Further, the sensor boss body is fixed to the outer peripheral surface of the heat shield case in the vicinity of the end face of one inner case, so that the inner case tube expansion allowance and the sensor boss body The distance between the end face of the gas purifier and the mounting position of the exhaust gas sensor can be formed to the shortest dimension (zero or arbitrary dimension) without being affected by the radius, welding allowance, and the like.

  Further, by forming the inner diameter of the fixing portion of the sensor boss body in the heat shield case larger than the outer diameter of the inner case, the heat shield case and the inner side inserted in the heat shield case By forming a gap between the case, the heat shield case and the inner case can be easily extracted. And the heat insulation of the opposing site | part of each said gas purification body can be improved with the said heat shielding case and the said outer case. The processing temperature of the particulate matter collected by the gas purifier can be easily maintained.

  Further, by fitting one end side of the heat shield case to the inner case and connecting the other end side of the heat shield case to a flange body for joining the outer cases, the inner case and The heat shield case can be supported with high rigidity by the flange body. It is possible to easily prevent the exhaust gas in the inner case from leaking toward the outer case through a gap with the heat shield case. An increase in the surface temperature of the outer case can be reduced.

  In addition, since the sensor mounting hole of the outer case is closed by the heat shielding case, the sensor boss body protrudes outward from the outer case, and the exhaust gas sensor can be easily connected to the measurement unit. . Electrical wiring and piping can be easily extended from the sensor boss body side. In addition, it is possible to easily prevent the exhaust gas in the inner case from leaking from the sensor mounting hole. An increase in the surface temperature of the outer case can be reduced.

  In addition, a gap is formed between the outer peripheral side of the other inner case where the other end side of the heat shield case is extended and the inner peripheral side of the heat shield case. On the other hand, the other inner case can be easily put in and out, and each inner case and each outer case can be easily joined or separated. Maintenance workability of each gas purifier or the exhaust gas sensor can be improved.

  Further, the inner case, the heat shield case, and the outer case are provided in a three-layer structure, the side end of the heat shield case is formed to be shorter than the side end of the outer case, and from the side end of the heat shield case. In addition, by forming the side end of the inner case in a short length, the temperature drop of the exhaust gas can be reduced, and the processing efficiency of the particulate matter in the exhaust gas can be improved. An increase in the surface temperature of the outer case can be reduced, and workability such as maintenance of the diesel engine that is required during operation can be improved.

It is a section explanatory view of DPF which shows a 1st embodiment. It is an external appearance perspective view of DPF. It is an external appearance top view of DPF. It is an external appearance bottom view of DPF. It is an external appearance front view of DPF. It is an external appearance side view of DPF. It is a cross-sectional side view of the upstream of DPF. It is a cross-sectional side view of the downstream of DPF. It is decomposition | disassembly cross-section explanatory drawing of DPF. It is a separation side view of a clamping flange (semi-arc body). It is an expanded side sectional view of a catalyst side joining flange. It is an expanded sectional view showing the attachment part of a sensor boss body. It is a top view of the diesel engine which provided DPF. It is an expanded sectional view which shows the attachment part of the sensor boss body of 2nd Embodiment. It is an expanded sectional view which shows the attachment part of the sensor boss body of 3rd Embodiment. It is an expanded sectional view showing the attachment part of the sensor boss body of a 4th embodiment. It is an expanded sectional view showing the attachment part of the sensor boss body of a 5th embodiment. It is an expanded sectional view showing the attachment part of the sensor boss body of a 6th embodiment.

  A first embodiment of an exhaust gas purifying apparatus embodying the present invention will be described below with reference to FIGS. 1 to 13. A continuously regenerating diesel particulate filter 1 (hereinafter referred to as DPF 1) as an exhaust gas purification device is provided. In addition to the removal of particulate matter (PM) in the exhaust gas of the diesel engine 70, the DPF 1 is configured to reduce carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas of the diesel engine 70. Yes.

  As shown in FIGS. 1, 6, and 13, the DPF 1 as an exhaust gas purification device is for collecting particulate matter (PM) and the like in the exhaust gas. The DPF 1 is configured in a substantially cylindrical shape extending long in the left-right direction intersecting the output shaft (crankshaft) of the diesel engine 70 in plan view. The DPF 1 is disposed on the flywheel housing 78 of the diesel engine 70. An exhaust gas inlet pipe 16 (exhaust gas intake side) and an exhaust gas outlet pipe 34 (exhaust gas discharge side) are provided on the left and right sides of the DPF 1 (one end side and the other end side in the exhaust gas movement direction). It distributes to the left and right. The exhaust gas inlet pipe 16 on the exhaust gas intake side of the DPF 1 is detachably bolted to the exhaust manifold 71 of the diesel engine 70. A tail pipe 107 is connected to the exhaust gas outlet pipe 34 on the exhaust gas discharge side of the DPF 1.

  As shown in FIGS. 1 to 6, a DPF 1 includes a DPF casing 60 made of a heat-resistant metal material and a diesel oxidation catalyst 2 such as platinum and a soot filter 3 having a honeycomb structure through a cylindrical inner case 4 or 20. It is a structure accommodated in series. The DPF 1 is attached to the flywheel housing 78 via a flange side bracket leg 61 and a casing side bracket leg 62 as a support. In this case, one end side of the flange-side bracket leg 61 is detachably bolted to the outer peripheral side of the DPF casing 60 via a flange 26 described later. One end side of the casing side bracket leg 62 is integrally fixed to the outer peripheral surface of the DPF casing 60 by welding.

  On the other hand, as shown in FIGS. 1 to 6 and 13, the other end side of the flange side bracket leg 61 is detachably fastened to the upper surface (DPF attachment portion) of the flywheel housing 78 with two retrofitting bolts 88. The The other end side of the casing side bracket leg 62 is detachably fastened to the upper surface (DPF attachment portion) of the flywheel housing 78 with a front bolt 87 and a rear bolt 88. On the other end side of the casing side bracket leg 62, a notch hole 89 for engaging the attaching bolt 87 is formed.

  That is, when the DPF 1 is assembled to the diesel engine 70, first, the leading bolt 87 is screwed incompletely on the upper surface of the flywheel housing 78. Then, the operator lifts the DPF 1 with both hands, and the casing-side bracket leg 62 is locked to the leading bolt 87 through the notch hole 89 to temporarily fix the DPF 1 to the diesel engine 70. In this state, the operator can release both hands from the DPF 1. Thereafter, the inlet flange body 17 is fastened to the exhaust manifold 71, and the exhaust gas inlet pipe 16 is fixed to the exhaust manifold 71.

  On the other hand, the flange side bracket leg 61 and the casing side bracket leg 62 are fastened to the upper surface of the flywheel housing 78 by three retrofitting bolts 88. Further, the front bolt 87 is also completely fastened, and the DPF 1 is detachably fixed to the upper surface of the flywheel housing 78. The DPF 1 can be removed in the reverse procedure. As a result, the DPF 1 is stably connected and supported to the rear part of the diesel engine 70 by the bracket legs 61 and 62 and the exhaust manifold 71 at the upper part of the flywheel housing 78 that is a highly rigid member. Moreover, the attachment or detachment operation | work of DPF1 to the diesel engine 70 can be performed by one operator.

  With the above configuration, the exhaust gas of the diesel engine 70 flows from the exhaust manifold 71 of the diesel engine 70 to the diesel oxidation catalyst 2 side in the DPF casing 60, and moves from the diesel oxidation catalyst 2 to the soot filter 3 side for purification. It is processed. Particulate matter in the exhaust gas cannot pass through the porous partition walls between the cells in the soot filter 3. That is, the particulate matter in the exhaust gas is collected by the soot filter 3. Thereafter, exhaust gas that has passed through the diesel oxidation catalyst 2 and the soot filter 3 is discharged to the tail pipe 107.

  When the exhaust gas passes through the diesel oxidation catalyst 2 and the soot filter 3, the exhaust gas temperature exceeds the reproducible temperature (for example, about 300 ° C.). NO (nitrogen monoxide) is oxidized to unstable NO2 (nitrogen dioxide). The particulate matter collected by the soot filter 3 is oxidized and removed by O (oxygen) released when NO2 returns to NO. In addition, when particulate matter accumulates on the soot filter 3, the particulate matter is oxidized and removed by maintaining the temperature of the exhaust gas at a temperature higher than the regenerative temperature. Is recovered (the soot filter 3 is regenerated).

  With reference to FIG.1 and FIG.9, the structure which assembles | assembles the diesel oxidation catalyst 2 which is an example of the exhaust-gas purification body (filter) which purifies the exhaust gas which the diesel engine 70 discharged | emitted is demonstrated. The diesel oxidation catalyst 2 is provided in a substantially cylindrical catalyst inner case 4 made of a heat-resistant metal material. The catalyst inner case 4 is formed in a substantially cylindrical catalyst outer case 5 made of a heat-resistant metal material. That is, the catalyst inner case 4 is fitted on the outside of the diesel oxidation catalyst 2 via the ceramic heat insulating material 6 made of ceramic fiber. A catalyst heat insulating material 6 is press-fitted between the diesel oxidation catalyst 2 and the catalyst inner case 4 to protect the diesel oxidation catalyst 2.

  Further, the catalyst outer case 5 is fitted on the outer side of the catalyst inner case 4 via an end plate L-shaped support 7. The catalyst outer case 5 is one of the elements that constitute the DPF casing 60 described above. Note that the diesel oxidation catalyst 2 is protected by the catalyst heat insulating material 6. The stress (mechanical vibration, deformation force) of the catalyst outer case 5 transmitted to the catalyst inner case 4 is reduced by the thin plate support 7.

  As shown in FIGS. 1 and 9, a disk-like side lid 8 is fixed to one end of the catalyst inner case 4 and the catalyst outer case 5 by welding. An outer lid body 9 is fastened to the outer surface side of the side lid body 8 with bolts and nuts. The gas inflow side end face 2a of the diesel oxidation catalyst 2 and the side lid 8 are separated by a certain distance L1 (gas inflow space 11). An exhaust gas inflow space 11 is formed between the gas inflow side end face 2 a of the diesel oxidation catalyst 2 and the left lid 8. An exhaust gas inlet 12 facing the exhaust gas inflow space 11 is opened in the catalyst inner case 4 and the catalyst outer case 5. A closing ring body 15 is fixed between the opening edge of the catalyst inner case 4 and the opening edge of the catalyst outer case 5 in a sandwiched manner. Since the gap between the opening edge of the catalyst inner case 4 and the opening edge of the catalyst outer case 5 is closed by the closing ring 15, the exhaust gas flows between the catalyst inner case 4 and the catalyst outer case 5. Can be prevented.

  As shown in FIGS. 1 to 6 and 9, an exhaust gas inlet pipe 16 is disposed on the outer surface of the catalyst outer case 5 in which the exhaust gas inlet 12 is formed. An inlet flange body 17 is welded and fixed to one open end of the exhaust gas inlet pipe 16. The inlet flange body 17 is detachably bolted to the exhaust manifold 71 of the diesel engine 70. One end of the exhaust gas inlet pipe 16 communicates with the exhaust manifold 71. The other open end of the exhaust gas inlet pipe 16 is welded to the outer surface of the catalyst outer case 5 so as to cover the exhaust gas inlet 12 from the outside. A pair of reinforcing bracket bodies 18 are fixed by welding between the outer surface of the catalyst outer case 5 and the side edges of the inlet flange body 17 to ensure the connection strength between the exhaust manifold 71 and the exhaust gas inlet pipe 16.

  With the above configuration, the exhaust gas of the diesel engine 70 enters the exhaust gas inlet pipe 16 from the exhaust manifold 71 and enters the exhaust gas inflow space 11 from the exhaust gas inlet pipe 16 through the exhaust gas inlet 12, and the diesel oxidation catalyst 2 is supplied from the gas inflow side end surface 2a on the left side. Nitrogen dioxide (NO 2) is generated by the oxidation action of the diesel oxidation catalyst 2.

  With reference to FIG.1 and FIG.9, the structure which assembles the soot filter 3 which is an example of the exhaust-gas purification body (filter) which purifies the exhaust gas which the diesel engine 70 discharged | emitted is demonstrated. The soot filter 3 is provided in a substantially cylindrical filter inner case 20 made of a heat-resistant metal material. The filter inner case 20 is provided in a substantially cylindrical filter outer case 21 made of a heat-resistant metal material. That is, the filter inner case 20 is fitted on the outside of the soot filter 3 through the mat-shaped filter heat insulating material 22 made of ceramic fiber. The filter outer case 21 is one of the elements constituting the DPF casing 60 described above together with the catalyst outer case 5. In addition, the filter heat insulating material 22 is press-fitted between the soot filter 3 and the filter inner case 20 to protect the soot filter 3.

  As shown in FIGS. 1 and 9, the catalyst inner case 4 formed in a cylindrical shape with a straight ridge line is a downstream side into which an upstream side cylinder portion 4 a for accommodating the diesel oxidation catalyst 2 and a filter inner case 20 described later are inserted. It is comprised by the side cylinder part 4b. In addition, the upstream side cylinder part 4a and the downstream side cylinder part 4b are cylinders of substantially the same diameter. Furthermore, a thin plate-shaped ring-shaped catalyst side joining flange 25 that is welded and fixed to the outer periphery of the catalyst inner case 4 and a thin plate-shaped ring-shaped filter side joint flange 26 that is welded and fixed to the outer periphery of the filter inner case 20 are provided. The catalyst-side joining flange 25 and the filter-side joining flange 26 are formed in a donut shape having an L-shaped cross section.

  The inner peripheral side of the L-shaped cross-section end face of the catalyst side joining flange 25 is welded and fixed to the end portion of the downstream side cylinder portion 4 b of the catalyst inner case 4. The outer peripheral side of the L-shaped cross-section end face of the catalyst side joining flange 25 is projected toward the outer peripheral side (radial direction) of the catalyst outer case 5. A step portion 25 a is formed at the bent corner portion of the L-shaped end face of the catalyst side joining flange 25. The downstream end of the catalyst outer case 5 is fixed by welding to the step portion 25a.

  On the other hand, the inner peripheral side of the L-shaped cross-section end face of the filter side joining flange 26 is welded and fixed to the middle part of the outer periphery of the filter inner case 20 in the exhaust gas movement direction. The outer peripheral side of the L-shaped cross-section end face of the filter-side joining flange 26 is projected toward the outer peripheral side (radial direction) of the filter outer case 21. A step portion 26 a is formed at the bent corner of the L-shaped end face of the filter-side joining flange 26. The upstream end of the filter outer case 21 is fixed by welding to the step portion 26a. In addition, the filter inner case 20 is formed in a cylindrical shape whose ridgeline is a straight line. The exhaust gas upstream end and the downstream end of the filter inner case 20 are cylinders having substantially the same diameter.

  Further, the outer diameter of the diesel oxidation catalyst 2 and the outer diameter of the soot filter 3 are formed to be equal. Compared with the thickness of the filter heat insulating material 22, the thickness of the catalyst heat insulating material 6 is formed larger. On the other hand, the catalyst inner case 4 and the filter inner case 20 are formed of the same plate thickness material. The outer diameter of the filter inner case 20 is made smaller than the inner diameter of the downstream cylindrical portion 4 b of the catalyst inner case 4. A downstream gap 23 is formed between the inner peripheral surface of the catalyst inner case 4 and the outer peripheral surface of the filter inner case 20. The downstream gap 23 is formed to have a dimension (for example, 2 millimeters) larger than the thickness (for example, 1, 5 millimeters) of each of the cases 4 and 20. For example, even if the cases 4 and 20 are rusted or thermally deformed, the exhaust gas upstream end of the filter inner case 20 can be easily put in and out of the downstream cylindrical portion 4 b of the catalyst inner case 4.

  As shown in FIGS. 1 to 5, 9, and 12, the catalyst-side joining flange 25 and the filter-side joining flange 26 are abutted with each other through the gasket 24. The joint flanges 25 and 26 are sandwiched from both sides in the exhaust gas movement direction by a pair of thick plate-like central clamping flanges 51 and 52 surrounding the outer peripheral sides of the outer cases 5 and 21. The catalyst outer case 5 and the filter outer case 21 are detachably connected by fastening the center clamping flanges 51 and 52 with the bolts 27 and the nuts 28 and clamping the joining flanges 25 and 26.

  As shown in FIGS. 1 and 12, the upstream end of the filter outer case 21 is connected to the downstream end of the catalyst outer case 5 through the center clamping flanges 51 and 52 and the joint flanges 25 and 26. Then, a catalyst downstream space 29 is formed between the diesel oxidation catalyst 2 and the soot filter 3. That is, the downstream end of the diesel oxidation catalyst 2 and the upstream end of the soot filter 3 (filter inner case 20) face each other with a distance L2 for sensor attachment.

  As shown in FIGS. 1 and 9, the cylindrical length L4 of the catalyst outer case 5 in the exhaust gas movement direction is longer than the cylindrical length L3 of the upstream cylinder portion 4a of the catalyst inner case 4 in the exhaust gas movement direction. To do. The cylindrical length L6 of the filter outer case 21 in the exhaust gas movement direction is shorter than the cylindrical length L5 of the filter inner case 20 in the exhaust gas movement direction. A length (L2 + L3 + L5) obtained by adding the sensor mounting interval L2 in the catalyst downstream space 29, the cylinder length L3 of the upstream cylinder portion 4a of the catalyst inner case 4 and the cylinder length L5 of the filter inner case 20 is It is configured to be substantially equal to a length (L4 + L6) obtained by adding the cylindrical length L4 of the catalyst outer case 5 and the cylindrical length L6 of the filter outer case 21.

  Further, the upstream end portion of the filter inner case 20 protrudes from the upstream end portion of the filter outer case 21 by a difference in length between the cases 20 and 21 (L7≈L5−L6). Therefore, in a state in which the filter outer case 21 is connected to the catalyst outer case 5, the upstream side dimension L 7 of the filter inner case 20 protruding from the filter outer case 21 is the downstream side of the catalyst outer case 5 (the downstream side of the catalyst inner case 4). The upstream end of the filter inner case 20 is inserted into the cylindrical part 4b). That is, the upstream side of the filter inner case 20 is inserted into the downstream side cylinder portion 4b (catalyst downstream side space 29) so as to be extractable.

  With the above configuration, nitrogen dioxide (NO 2) generated by the oxidation action of the diesel oxidation catalyst 2 is supplied into the soot filter 3 from one side end face (intake side end face) 3 a. Particulate matter (PM) contained in the exhaust gas of the diesel engine 70 is collected by the soot filter 3 and continuously oxidized and removed by nitrogen dioxide (NO2). In addition to the removal of particulate matter (PM) in the exhaust gas of the diesel engine 70, the content of carbon monoxide (CO) and hydrocarbon (HC) in the exhaust gas of the diesel engine 70 is reduced.

  As shown in FIGS. 1, 8, and 9, the silencer 30 for attenuating exhaust gas noise discharged from the diesel engine 70 is made of a heat-resistant metal material and is made of a substantially cylindrical silencer inner case 31 and made of a heat-resistant metal material. A cylindrical silencer outer case 32 and a disk-like side lid 33 fixed to the downstream side end of the silencer outer case 32 by welding. A silencer inner case 31 is provided in the silencer outer case 32. The muffler outer case 32 and the catalyst outer case 5 and the filter outer case 21 constitute the DPF casing 60 described above. The diameter of the cylindrical silencer outer case 32 is substantially the same as the diameter of the cylindrical catalyst outer case 5 or the diameter of the cylindrical filter outer case 21.

  Disc-shaped inner lid bodies 36 and 37 are fixed to both ends of the muffler inner case 31 in the exhaust gas movement direction by welding. A pair of exhaust gas introduction pipes 38 is provided between the inner lid bodies 36 and 37. The upstream end of each exhaust gas introduction pipe 38 passes through the upstream inner lid 36. The downstream end portion of each exhaust gas introduction pipe 38 is closed by a downstream inner lid body 37. A plurality of communication holes 39 are formed in an intermediate portion of each exhaust gas introduction pipe 38. An expansion chamber 45 is communicated with each exhaust gas introduction pipe 38 through a communication hole 39. The expansion chamber 45 is formed inside the silencer inner case 31 (between the inner lids 36 and 37).

  Exhaust gas outlet pipes 34 arranged between the exhaust gas introduction pipes 38 are passed through the silencer inner case 31 and the silencer outer case 32. One end side of the exhaust gas outlet pipe 34 is closed by an outlet lid 35. A large number of exhaust holes 46 are formed in the entire exhaust gas outlet pipe 34 inside the silencer inner case 31. Each exhaust gas introduction pipe 38 communicates with the exhaust gas outlet pipe 34 via a plurality of communication holes 39, an expansion chamber 45 and a number of exhaust holes 46. A tail pipe 48 is connected to the other end side of the exhaust gas outlet pipe 34. With the above configuration, the exhaust gas that has entered the both exhaust gas introduction pipes 38 of the silencer inner case 31 passes through the exhaust gas outlet pipe 34 via the plurality of communication holes 39, the expansion chambers 45, and the numerous exhaust holes 46. The sound is discharged out of the silencer 30 through the tail pipe 48.

  As shown in FIGS. 1 and 9, the inner diameter side of the filter outlet side joining flange 40 having a thin ring shape is welded and fixed to the downstream end of the filter inner case 20. The outer diameter side of the filter outlet side joining flange 40 is projected toward the outer peripheral side (radius outside, radial direction) of the filter outer case 21. The downstream end of the filter outer case 21 is fixed by welding to the outer peripheral side of the filter outlet side joining flange 40 (corner corner of the end face L shape). A thin-plate-like silencer-side joining flange 41 that protrudes from the outer peripheral side (radius outside) of the silencer outer case 32 is welded and fixed to the upstream end of the silencer inner case 31. In addition, the upstream side of the silencer inner case 31 is protruded by a predetermined cylindrical dimension L10 on the exhaust gas upstream side of the silencer side joining flange 41. The upstream end of the silencer outer case 32 is fixed by welding to the outer peripheral surface of the silencer inner case 31 on the downstream side of the silencer side joining flange 41.

  As shown in FIG. 1 and FIG. 7 to FIG. 10, a pair of thick plates that butt the filter outlet side joining flange 40 and the muffler side joining flange 41 through the gasket 24 and surround the outer peripheral sides of the outer cases 21 and 32. The outlet flanges 53 and 54 hold the joint flanges 40 and 41 from both sides in the exhaust gas movement direction. The filter outer case 21 and the silencer outer case 32 are detachably connected by fastening the outlet clamping flanges 53 and 54 to the joint flanges 40 and 41 with bolts 42 and nuts 43, respectively.

  As shown in FIG. 1 and FIG. 9, the cylindrical length L9 of the silencer outer case 32 in the exhaust gas movement direction is shorter than the cylindrical length L8 of the silencer inner case 31 in the exhaust gas movement direction. The upstream end of the silencer inner case 31 protrudes from the upstream end (joining flange 41) of the silencer outer case 32 by a difference in length between the cases 31 and 32 (L10≈L8−L9). . In other words, in a state where the silencer outer case 32 is connected to the filter outer case 21, the downstream end (filter outlet side joining flange 40) of the filter outer case 21 is only the dimension L10 where the upstream end of the silencer inner case 31 protrudes. The upstream end portion of the muffler inner case 31 is inserted into the filter downstream space 49 formed inside.

  As shown in FIGS. 1 and 7 to 10, the thick plate-like central clamping flange 51 (52) is divided into a plurality (two in the embodiment) in the circumferential direction of the catalyst outer case 5 (filter outer case 21). The semicircular arc bodies 51a and 51b (52a and 52b) are used. The semicircular arc bodies 51a and 51b (52a and 52b) of the embodiment are formed in an arc shape (substantially semicircular horseshoe shape). In a state where the filter outer case 21 is connected to the catalyst outer case 5, the respective end portions of the semicircular arc bodies 51a and 51b (52a and 52b) come into contact with each other. That is, the semicircular arc members 51a and 51b (52a and 52b) are configured so that the outer peripheral side of the catalyst outer case 5 (filter outer case 21) is annularly surrounded.

  The central clamping flange 51 (52) is provided with a plurality of bolt fastening portions 55 with through holes at equal intervals along the circumferential direction. In the embodiment, eight bolt fastening portions 55 are provided on one set of central clamping flanges 51. When viewed in units of the semicircular arc bodies 51a and 51b (52a and 52b), the bolt fastening portions 55 are provided at four locations at equal intervals along the circumferential direction. On the other hand, bolt holes 56 corresponding to the respective bolt fastening portions 55 of the center clamping flange 51 (52) are formed through the catalyst side joining flange 25 and the filter side joining flange 26.

  When connecting the catalyst outer case 5 and the filter outer case 21, the outer peripheral side of the catalyst outer case 5 is surrounded by the catalyst-side semicircular arcs 51 a and 51 b, and the outer peripheral side of the filter outer case 21 is both on the filter side. The catalyst-side joining flange 25 and the filter-side joining flange 26, which are enclosed by the semicircular arc bodies 52a and 52b and sandwich the gasket 24, are joined from both sides in the exhaust gas movement direction by these semicircular arc bodies (center clamping flanges 51 and 52). Hold it.

  In this state, the bolts 27 are inserted into the bolt fastening portions 55 of the center clamping flanges 51 and 52 on both sides and the bolt holes 56 of the joint flanges 25 and 26 and tightened with the nuts 28. As a result, the joint flanges 25 and 26 are sandwiched and fixed by the center sandwich flanges 51 and 52, and the connection between the catalyst outer case 5 and the filter outer case 21 is completed. Here, the abutting portions of the ends of the catalyst-side semicircular arcs 51a and 51b and the filter-side semicircular arcs 52a and 52b are configured to be positioned with a phase shift of 72 °.

  As shown in FIGS. 1 and 7 to 10, the thick plate-shaped outlet pinching flange 53 (54) is divided into a plurality (two in the embodiment) in the circumferential direction of the filter outer case 21 (silencer outer case 32). The semicircular arc bodies 53a and 53b (54a and 54b) are used. The semicircular arc bodies 53a, 53b (54a, 54b) of the embodiment have basically the same form as the semicircular arc bodies 51a, 51b (52a, 52b) of the center clamping flange 51 (52). The outlet clamping flange 53 (54) is also provided with a plurality of bolt fastening portions 57 with through holes at equal intervals along the circumferential direction. On the other hand, bolt holes 58 corresponding to the respective bolt fastening portions 57 of the outlet clamping flange 53 (54) are formed through the filter outlet side joining flange 40 and the silencer side joining flange 41.

  When connecting the filter outer case 21 and the silencer outer case 32, the outer periphery side of the filter outer case 21 is surrounded by both semicircular arcs 53 a and 53 b on the filter outlet side, and the outer periphery side of the silencer outer case 32 is the silencer side. The filter outlet side joining flange 40 and the muffler side joining flange 41, which are surrounded by both the semicircular arc bodies 54a and 54b and sandwich the gasket 24, are arranged in the exhaust gas movement direction by these semicircular arc bodies (exit sandwiching flanges 53 and 54). Clamp from both sides.

  In this state, the bolts 42 are inserted into the bolt fastening portions 57 of the outlet clamping flanges 53 and 54 on both sides and the bolt holes 58 of the joint flanges 40 and 41 and tightened with the nuts 43. As a result, both the joining flanges 40 and 41 are sandwiched and fixed by the both outlet sandwiching flanges 53 and 54, and the connection between the filter outer case 21 and the silencer outer case 32 is completed. Here, the abutting portions of the ends of the semicircular arc bodies 53a and 53b on the filter outlet side and the semicircular arc bodies 54a and 54b on the silencer side are configured to be positioned with a phase shift of 72 °.

  As shown in FIGS. 1 and 7 to 10, at least one of the sandwiching flanges 51 to 54 has a left bracket leg as a support for supporting the DPF casing 60 (outer cases 5, 21, 32) on the diesel engine 70. 61 is attached. In the embodiment, in one of the semicircular arc bodies 53a of the outlet holding flange 53 on the filter outlet side, the support body fastening portion 59 with a through hole is integrated at two locations so as to be positioned between the adjacent bolt fastening portions 57. Is formed. On the other hand, the left bracket leg 61 is integrally formed with a mounting boss portion 86 corresponding to the support body fastening portion 59 described above.

  With the above configuration, the mounting boss portion 86 of the left bracket leg 61 is bolted to the support fastening portion 59 of one semicircular arc member 53a on the filter outlet side, so that the left side of the outlet clamping flange 53 on the filter outlet side The bracket leg 61 is detachably fixed. One end side of the right bracket leg 62 is welded and fixed to the outer peripheral side of the DPF casing 60 (catalyst outer case 5), and the other end sides of the left and right bracket legs 61 and 62 are DPF formed on the upper surface of the flywheel housing 78. As described above, the bolts are fastened to the attachment portion 80. As a result, the DPF 1 is stably connected and supported on the upper portion of the flywheel housing 78 that is a highly rigid member by the left and right bracket legs 61 and 62 and the exhaust gas exhaust pipe 103 of the turbine case 101.

  As shown in FIGS. 1 and 7 to 10, the gas purifier (diesel oxidation catalyst 2, soot filter 3) that purifies the exhaust gas exhausted by the engine 70, and the respective interiors in which the diesel oxidation catalyst 2 and soot filter 3 are built. It has cases 4, 20, and 31 and outer cases 5, 21, and 32 that house the inner cases 4, 20, and 31, respectively. The inner cases 4, 20, 31 are connected to the outer cases 5, 21, 32 via joint flanges 25, 26, 40, 41 that protrude from the outer peripheral side of the outer cases 5, 21, 32. . The gas purifier (diesel oxidation catalyst 2, soot filter 3), a plurality of combinations of the inner cases 4, 20, 31 and the outer cases 5, 21, 32 are provided, and the joining flanges 25, 26 (40, 41) are provided. A plurality of outer cases 5, 21, 32 are connected by being clamped and fixed by a pair of clamping flanges 51, 52 (53, 54).

  Therefore, the adjacent joining flanges 25 and 26 (40, 41) can be clamped (contacted) by being sandwiched from both sides by the sandwiching flanges 51, 52 (53, 54). In addition, since the sandwiching flanges 51 to 54 are configured separately without being welded to the outer cases 5, 21, 32, the stress caused by welding in the relationship between the sandwiching flanges 51 to 54 and the outer cases 5, 21, 32. There is no risk of concentration or distortion problems. Therefore, a substantially uniform pressure contact force can be applied to the entire joining flanges 25 and 26 (40, 41), and the surface pressure of the sealing surfaces (clamping surfaces) of the clamping flanges 51 to 54 can be maintained at a high level. As a result, it is possible to reliably prevent exhaust gas leakage from between the joint flanges 25 and 26 (40 and 41).

  As shown in FIG. 1 and FIGS. 7 to 10, each of the holding flanges 51 to 54 has horseshoe-shaped semicircular arcs 51 a and 51 b (52 a, 52 b, and 53 a) that are divided into a plurality in the circumferential direction of the outer cases 5, 21, and 32. 53b, 54a, 54b), and is configured to surround the outer peripheral side of the outer cases 5, 21, 32 by a plurality of semicircular arc members 51a, 51b (52a, 52b, 53a, 53b, 54a, 54b). Yes. Therefore, although it is the clamping flanges 51-54 comprised by several semi-arc body 51a, 51b (52a, 52b, 53a, 53b, 54a, 54b), it will be in the same assembly | attachment state as an integrated object. For this reason, it is easy to assemble the holding flanges 51 to 54 as compared with the ring-shaped one, and the assembling workability can be improved. Moreover, DPF1 with high sealing performance can be comprised, suppressing processing cost and assembly | attachment cost.

  Next, the detailed structure of each joint flange 25, 26, 40 will be described with reference to FIG. Since each of the joining flanges 25, 26, 40 has basically the same structure, the catalyst side joining flange 25 that is welded and fixed to the catalyst inner case 4 and the catalyst outer case 5 will be described as a representative example. FIG. 11 shows an enlarged side sectional view of the catalyst side joining flange 25 in the embodiment. As shown in FIG. 11, the catalyst-side joining flange 25 has a step portion 25a whose end face in the cross section is bent in a step shape in the middle of the L shape. The downstream end portion of the catalyst outer case 5 is fitted on the step portion 25 a, and the step portion 25 a is welded and fixed to the downstream end portion of the catalyst outer case 5.

  On the other hand, an L-shaped inner diameter side end 25b of the catalyst side joining flange 25 extends in the extending direction (exhaust gas movement direction) of the catalyst inner case 4 (catalyst outer case 5). The inner diameter side end portion 25 b is fitted on the downstream end portion of the catalyst inner case 4, and the inner diameter side end portion 25 b is welded and fixed to the catalyst inner case 4. On the other hand, an L-shaped outer diameter side end portion 25c of the catalyst side joining flange 25 is extended from the outer periphery of the catalyst outer case 5 in the radial direction (vertical direction). The high rigidity of the catalyst side joining flange 25 is ensured by the cross-sectional end face L shape of the catalyst side joining flange 25 and the formation of the step portion 25a.

  The clamping flanges 51, 52 and the joining flanges 25, 26 are inserted into the clamping flanges 51, 52 and the joining flanges 25, 26 through the respective bolt holes 56, and the nuts 28 are screwed together. The outer diameter side end 25c of the catalyst side joining flange 25 is clamped by the clamping flanges 51 and 52 as described above.

  Next, as shown in FIGS. 1 and 12, the upstream gas temperature sensor 109 (downstream gas temperature sensor 112) attached to the DPF 1 will be described. One end of the cylindrical sensor boss body 110 is welded and fixed to the outer peripheral surface of the catalyst inner case 4 between the upstream cylinder portion 4 a and the downstream cylinder portion 4 b of the catalyst inner case 4. From the sensor mounting opening 5a of the catalyst outer case 5, the other end side of the sensor boss body 110 is extended in the radial direction toward the outside of the case 5. A sensor mounting bolt 111 is screwed to the other end side of the sensor boss body 110. For example, a thermistor type upstream gas temperature sensor 109 is passed through the sensor mounting bolt 111, and the upstream gas temperature sensor 109 is supported by the sensor boss body 110 via the sensor mounting bolt 111. A detection portion of the upstream gas temperature sensor 109 is inserted into the catalyst downstream space 29.

  With the above configuration, when exhaust gas is discharged from the gas outflow side end surface 2 b of the diesel oxidation catalyst 2, the exhaust gas temperature is detected by the upstream gas temperature sensor 109. In the same manner as described above, as shown in FIG. 1, for example, a thermistor type downstream gas temperature sensor 112 is attached to the sensor boss body 110 via a sensor mounting bolt 111, and the other end face (discharge end face) 3b of the soot filter 3 is attached. The downstream gas temperature sensor 112 detects the temperature of the exhaust gas.

  Next, a differential pressure sensor 63 attached to the DPF 1 will be described as shown in FIG. The differential pressure sensor 63 is for detecting the pressure difference of the exhaust gas between the upstream side and the downstream side across the soot filter 3 in the DPF 1. Based on the pressure difference, the amount of particulate matter deposited on the soot filter 3 is converted, and the clogged state in the DPF 1 can be grasped. That is, based on the pressure difference of the exhaust gas detected by the differential pressure sensor 63, the regeneration control of the soot filter 3 can be automatically executed by operating an accelerator control means or an intake throttle control means (not shown), for example. It is configured.

  The sensor bracket 66 is bolted to the mute-side outlet clamping flange 54 described above, and the sensor bracket 66 is disposed on the upper surface side of the DPF casing 60. A detection main body 67 of the differential pressure sensor 63 is attached to the sensor bracket 66. An upstream pipe joint body 64 and a downstream pipe joint body 65 are connected to a detection main body 67 of the differential pressure sensor 63 via an upstream sensor pipe 68 and a downstream sensor pipe 69, respectively. Similar to the sensor boss body 110, the sensor boss body 113 is disposed in the DPF casing 60. The upstream side pipe joint body 64 (downstream side pipe joint body 65) is fastened to the sensor boss body 113 by the pipe joint bolt 114.

  Next, a second embodiment of the DPF 1 (exhaust gas purification device) according to the present invention will be described with reference to FIG. FIG. 14 is an enlarged cross-sectional view showing a mounting portion of the sensor boss body of the second embodiment. The catalyst inner case 4 includes an upstream cylinder portion 4a that houses the diesel oxidation catalyst 2 and a downstream cylinder portion 4b into which the filter inner case 20 is inserted. The upstream cylindrical portion 4a is formed in a small diameter cylindrical shape with respect to the downstream cylindrical portion 4b. The upstream side cylinder part 4a and the downstream side cylinder part 4b are integrally connected via the step part 4c. The sensor boss body 110 is welded and fixed to the outer peripheral surface of the upstream cylindrical portion 4a located near the stepped portion 4c in the outer peripheral surface of the upstream cylindrical portion 4a. The sensor boss body 110 can be fixed to the highly rigid position of the upstream cylindrical portion 4a close to the stepped portion 4c by using the upstream cylindrical portion 4a. The gas temperature sensors 109 and 112 can be supported close to the gas outflow side end surface 2b of the diesel oxidation catalyst 2. In addition, the small diameter upstream cylinder part 4a and the filter inner case 20 are formed in a cylindrical shape having the same diameter.

  Next, a third embodiment of the DPF 1 (exhaust gas purification device) according to the present invention will be described with reference to FIG. FIG. 15 is an enlarged cross-sectional view showing a mounting portion of the sensor boss body of the third embodiment. The catalyst inner case 4 includes an upstream cylinder portion 4a that houses the diesel oxidation catalyst 2 and a downstream cylinder portion 4b into which the filter inner case 20 is inserted. The upstream side cylinder part 4a is formed in a cylindrical shape with a smaller diameter than the downstream side cylinder part 4b. The upstream side cylinder part 4a and the downstream side cylinder part 4b are integrally connected via the step part 4c. The sensor boss body 110 is welded and fixed to the outer peripheral surface of the upstream cylindrical portion 4a located near the stepped portion 4c and the stepped portion 4c among the outer peripheral surface of the upstream cylindrical portion 4a. The sensor boss body 110 can be fixed to the highly rigid position of the catalyst inner case 4 using the upstream side cylinder part 4a and the step part 4c. Mechanical vibrations of the gas temperature sensors 109 and 112 can be reduced. In addition, the small diameter upstream cylinder part 4a and the filter inner case 20 are formed in a cylindrical shape having the same diameter.

  Next, a fourth embodiment of the DPF 1 (exhaust gas purification device) according to the present invention will be described with reference to FIG. FIG. 16 is an enlarged cross-sectional view showing a mounting portion of the sensor boss body of the fourth embodiment. The filter inner case 20 includes an upstream cylinder portion 20 a into which the catalyst inner case 4 is inserted and a downstream cylinder portion 20 b that houses the soot filter 3. The catalyst inner case 4 is formed in a smaller diameter cylindrical shape than the filter inner case 20. That is, the catalyst inner case 4 and the filter inner case 20 have a cylindrical shape with a straight ridge line, and have the same diameter on both ends. On the other hand, the sensor boss body 110 is fixed to the upstream cylindrical portion 20a, and the gas temperature sensor 109 is inserted into the upstream cylindrical portion 20a which is the catalyst downstream space 29. The end of the upstream cylinder portion 20a is detachably fixed to the outer peripheral surface of the catalyst inner case 4 via the joining flanges 25 and 26 on the upstream side of the gas outflow side end surface 2b of the diesel oxidation catalyst 2. Yes. The fourth embodiment has the same effect as the first embodiment.

  Next, with reference to FIG. 17 and FIG. 18, 5th Embodiment and 6th Embodiment of DPF1 (exhaust gas purification apparatus) which concerns on this invention are described. FIG. 17 is an enlarged cross-sectional view showing a mounting portion of the sensor boss body of the fifth embodiment. FIG. 18 is an enlarged cross-sectional view showing a mounting portion of the sensor boss body of the sixth embodiment. As shown in FIG. 17 or FIG. 18, a heat shielding case 190 is provided on the outer surface of one of the catalyst inner case 4 and the catalyst inner case 4. The catalyst inner case 4 and the filter inner case 20 are formed in a cylindrical shape having the same diameter. That is, the catalyst inner case 4 and the filter inner case 20 have a cylindrical shape with a straight ridge line, and have the same diameter on both ends. A downstream gap 23 similar to that of the first embodiment is formed between the outer peripheral surfaces of the catalyst inner case 4 and the filter inner case 20 and the inner peripheral surface of the heat shield case 190.

  As shown in FIG. 17 or FIG. 18, the upstream side of the heat shield case 190 is formed in a cylindrical shape having a smaller diameter than the downstream side, and the small diameter cylindrical upstream end of the heat shield case 190 is formed on the outer peripheral surface of the catalyst inner case 4. The upstream side of the heat shield case 190 is welded and fixed to the catalyst inner case 4. One end side of the heat shielding case 190 is fixed to the outer peripheral surface on the inner side of the downstream end surface of the one catalyst inner case 4. On the other hand, the upstream side (exhaust gas intake side end) of the other filter inner case 20 is inserted into the heat shield case 190. Between the gas outlet side end surface 2b of the diesel oxidation catalyst 2 in the catalyst inner case 4 and one side end surface (intake side end surface) 3a of the soot filter 3 in the filter inner case 20, the same catalyst downstream as in the first embodiment. A side space 29 is formed.

  As shown in FIG. 17 or FIG. 18, the inner cases 4, 20, the heat shield case 190, and the catalyst outer case 5 are provided in a three-layer structure, and the downstream end of the heat shield case 190 rather than the downstream end of the catalyst outer case 5. And the downstream end of the catalyst inner case 4 is formed shorter than the downstream end of the heat shield case. That is, one end side (upstream side) of the heat shield case 190 is fitted to one catalyst inner case 4, and the heat shield case is connected to the catalyst side joint flange 25 as a flange body for joining the outer cases 5 and 21. The end side is connected by welding. The sensor mounting opening 5 a of the catalyst outer case 5 is closed by a heat shield case 190. On the other hand, the other end side (downstream side) of the heat shielding case 190 extended to the outer surface of the other filter inner case 20 is connected to the catalyst side joint flange 25 as a flange body for joining the outer cases 5 and 21. doing. A downstream gap 23, which is a space, is formed between the outer peripheral side of the other filter inner case 20 where the other end side (downstream side) of the heat shield case 190 is extended and the inner peripheral side of the heat shield case 190. Yes.

  As shown in FIG. 17 or FIG. 18, the sensor boss body 113 or 110 is fixed to the outer peripheral surface of the heat shield case 190 in the vicinity of the end face of one catalyst inner case 4. The inner diameter of the sensor boss body 113 or 110 fixing portion in the heat shield case 190 is formed larger than the outer diameter of the catalyst inner case 4 (filter inner case 20).

  As shown in FIG. 17, an upstream gap 23 a is formed between the catalyst inner case 4 and the heat shielding case 190 on the upstream side of the downstream end portion of the catalyst inner case 4. One end side of the cylindrical sensor boss body 113 is welded and fixed to the upstream outer peripheral surface of the heat shielding case 190. The upstream side pipe joint body 64 is fastened to the sensor boss body 113 by the pipe joint bolt 114. A detection main body 67 of a differential pressure sensor 63 is connected to the upstream pipe joint body 64 via an upstream sensor pipe 68.

  As shown in FIG. 17, a sensor opening 190b that allows the hollow portion of the sensor boss body 113 to communicate with the upstream gap 23a is formed. When exhaust gas is discharged from the gas outflow side end face 2b of the diesel oxidation catalyst 2 to the catalyst downstream space 29, a part of the exhaust gas in the catalyst downstream space 29 becomes an upstream gap 23a, a sensor opening 190b, a sensor boss. It is configured to move to the detection main body 67 side through the hollow portion of the body 113, the hollow portion of the upstream side pipe joint body 64, and the upstream side sensor pipe 68.

  With the above configuration, when the exhaust gas in the catalyst downstream space 29 moves in the direction of the sensor opening 190b, the particulate matter contained in the exhaust gas is blocked from the corners of the downstream end of the catalyst inner case 4. Deposits between thermal cases 190. Therefore, the amount of particulate matter deposited on the edge of the sensor opening 190b is reduced as compared with the structure in which the sensor opening is directly opened toward the catalyst downstream space 29. The exhaust gas inflow pressure of the sensor opening 190b can be maintained below a predetermined pressure.

  In particular, since the area of the upstream gap 23a formed over the entire circumference between the catalyst inner case 4 and the heat shield case 190 can be made larger than the area of the sensor opening 190b, the catalyst inner case 4 and the heat shield case can be formed. Even if the particulate matter accumulates in a part of the upstream gap 23a between 190, the exhaust gas is supplied from the other upstream gap 23a to the sensor opening 190b. That is, the diesel engine 70 can be continuously operated over a long period of time so that the particulate matter accumulates in the entire area of the upstream gap 23a formed over the entire circumference between the catalyst inner case 4 and the heat shielding case 190. . The maintenance work interval for removing the particulate matter accumulated in the sensor opening 190b can be set longer. While the diesel engine 70 can be continuously operated for a long time, the detection accuracy of the differential pressure sensor 63 can be maintained for a long time.

  As shown in FIG. 18, one end side of the cylindrical sensor boss body 110 is welded and fixed to the outer peripheral surface of the heat shield case 190 (part where the catalyst downstream space 29 is formed). The other end side of the sensor boss body 110 is extended in the radial direction from the sensor mounting opening 5 a of the catalyst outer case 5 toward the outside of the case 5. A sensor mounting bolt 111 is screwed to the other end side of the sensor boss body 110. A thermistor-type upstream gas temperature sensor 109 is passed through the sensor mounting bolt 111, and the upstream gas temperature sensor 109 is supported by the sensor boss body 110 via the sensor mounting bolt 111. A detection portion of the upstream gas temperature sensor 109 is inserted into the catalyst downstream space 29.

  With the above configuration, for example, a part of the sensor boss body 110 can be positioned on the upstream side of the gas outflow side end surface 2b of the diesel oxidation catalyst 2 until the gas oxidization catalyst 2 comes into contact with the gas outflow side end surface 2b. The sensor boss body 110 can be arranged on the outer peripheral surface of the heat shield case 190 so that the upstream gas temperature sensor 109 approaches the gas outflow side end surface 2b. Further, by increasing the thickness of each outer case 5, 21, the thickness of each inner case 4, 20 and the heat shielding case 190 can be reduced, and the soot filter 3 can be maintained at a regeneration temperature or higher. Nevertheless, the weight of the DPF 1 can be reduced.

  As shown in FIGS. 1, 9, 12, and 14 to 18, a diesel oxidation catalyst 2 or soot filter 3 for purifying exhaust gas discharged from the diesel engine 70 and a diesel oxidation catalyst 2 or soot filter 3 are provided internally. The catalyst inner case 4 or the filter inner case 20 is provided, and the catalyst outer case 5 or the filter outer case 21 in which the catalyst inner case 4 or the filter inner case 20 is installed is provided. Then, the outlet end portion (gas outflow side end portion) of the catalyst inner case 4 on the exhaust upstream side and the inlet end portion (gas intake side end portion) of the filter inner case 20 on the exhaust downstream side are polymerized into a double structure, Sensor boss bodies 110 and 113 for supporting an exhaust gas sensor are arranged on the outer end face of the dual structure outlet end or inlet end, and the sensor boss bodies 110 and 113 are extended outward of the catalyst outer case 5. A differential pressure sensor (exhaust gas pressure sensor) 63 and an upstream gas temperature sensor (exhaust gas temperature sensor) 109 are provided as exhaust gas sensors.

  Therefore, the upstream gas temperature sensor 109 (exhaust gas temperature sensor), the pipe 68 of the differential pressure sensor 63 (exhaust gas pressure sensor), and the like can be easily assembled via the sensor boss bodies 110 and 113. In addition, it is possible to easily reduce the exhaust gas temperature in the catalyst inner case 4 or the filter inner case 20 from being lowered by the heat insulating (warming) action of the catalyst outer case 5 or the filter outer case 21. By maintaining the exhaust gas temperature inside the filter inner case 20, it is possible to reduce the stagnation of particulate matter in the exhaust gas inside the soot filter 3, and it is not necessary to regenerate the soot filter 3 at a high frequency. Gas purification performance can be improved. On the other hand, since an increase in the outer surface temperature of the catalyst outer case 5 or the filter outer case 21 is suppressed, maintenance of the diesel engine 70 and the like can be performed before the DPF 1 or the diesel engine 70 is cooled. Can be improved.

  As shown in FIG. 17 or FIG. 18, a heat shield case 190 is provided on the outer surface of one catalyst inner case 4, and the other filter inner case 20 is inserted into the heat shield case 190, while one catalyst inner case 4 One end of the heat shield case 190 is fixed to the outer peripheral surface on the inner side of the end surface, and the sensor boss body 110 is fixed to the outer peripheral surface of the heat shield case 190 near the end surface of one catalyst inner case 4.

  Therefore, the catalyst outer case 5 and the heat shield case 190 can be extended to the part where the diesel oxidation catalyst 2 and the soot filter 3 face each other, and the exhaust gas temperature in the filter inner case 20 can be easily set by the catalyst outer case 5 and the heat shield case 190. Can be maintained. Moreover, while the catalyst inner case 4 and the filter inner case 20 can be formed to have the same diameter, the facing distance L2 between the diesel oxidation catalyst 2 and the soot filter 3 can be formed to the shortest dimension. In other words, compared with the conventional structure in which the enlarged diameter portion is provided, the end face of the diesel oxidation catalyst 2 and the upstream gas temperature sensor 109 can be attached without being affected by the expansion allowance of the catalyst inner case, the radius of the sensor boss body, the welding allowance, and the like. The position interval can be formed to the shortest dimension (zero or arbitrary dimension). As a result, the total length of the DPF 1 can be shortened, and the DPF 1 can be easily mounted on various devices. The upstream gas temperature sensor 109 can be brought close to the end surface of the diesel oxidation catalyst 2 until it comes into contact with the end surface of the diesel oxidation catalyst 2, and the control performance such as automatic regeneration processing of the DPF 1 can be improved.

  As shown in FIG. 17 or FIG. 18, the inner diameter of the portion of the heat shield case 190 to which the sensor boss body 110 is fixed is formed larger than the outer diameter of the catalyst inner case 4 or the filter inner case 20. By forming the downstream gap 23 between the heat shield case 190 and the filter inner case 20 inserted in the heat shield case 190, the filter inner case 20 can be easily extracted from the heat shield case 190. . In addition, the heat insulation case 190 and the catalyst outer case 5 can improve the heat insulation of the part where the diesel oxidation catalyst 2 and the soot filter 3 face each other. The oxidation treatment temperature (regeneration temperature) of the particulate matter in the exhaust gas collected by the soot filter 3 can be easily maintained.

  As shown in FIG. 17 or FIG. 18, one end side of the heat shielding case 109 is fitted to the catalyst inner case 4, and the heat shielding case 190 is attached to the catalyst side joining flange 25 (flange body) for joining the outer cases 5 and 21. Therefore, the heat shield case 190 can be supported by the catalyst inner case 4 and the catalyst side joining flange 25 with high rigidity. It is possible to easily prevent the exhaust gas in the catalyst inner case 4 or the filter inner case 20 from leaking from the downstream gap 23 to the heat shielding case 190 toward the outer cases 5 and 21. An increase in the surface temperature of each outer case 5, 21 can be reduced.

  As shown in FIG. 17 or FIG. 18, the sensor mounting opening 5 a (sensor mounting hole) of the catalyst outer case 5 is closed by the heat shield case 190. The upstream sensor pipe 68 of the differential pressure sensor 63 or the upstream gas temperature sensor 109 (exhaust gas sensor) can be easily connected to the measurement unit. Electrical wiring and piping can be easily extended from the sensor boss bodies 110 and 113 side. Moreover, it is possible to easily prevent the exhaust gas in the catalyst inner case 4 or the filter inner case 20 from leaking from the sensor mounting opening 5a. An increase in the surface temperature of the catalyst outer case 5 or the filter outer case 21 can be reduced.

  As shown in FIG. 17 or FIG. 18, a downstream gap 23 is formed between the outer peripheral side of the other filter inner case 20 with the other end of the heat shielding case 190 extended and the inner peripheral side of the heat insulating case 190. Therefore, the other filter inner case 20 can be easily moved in and out of the heat shield case 190, and the inner cases 4 and 20 and the outer cases 5 and 21 can be easily joined or separated. Maintenance workability of the diesel oxidation catalyst 2 as the gas purifier, the soot filter 3, or the gas temperature sensor 109 as the exhaust gas sensor, the downstream gas temperature sensor 112, the differential pressure sensor 63, and the like can be improved.

  As shown in FIG. 17 or FIG. 18, a heat shielding case 190 extended to the outer surface of the other filter inner case 20 on the catalyst side joining flange 25 (flange body) for joining the catalyst outer case 5 and the filter outer case 21. Therefore, it is possible to easily prevent the exhaust gas from leaking from the diesel oxidation catalyst 2 toward the outer cases 5 and 21. Due to the heat insulating action of the outer cases 5 and 21 and the heat shielding case 190, it is possible to reduce a decrease in the exhaust gas temperature of the soot filter 3, an increase in the surface temperature of the outer cases 5 and 21, and the like.

  As shown in FIG. 17 or FIG. 18, the catalyst inner case 4 (filter inner case 20), the heat shield case 190, and the catalyst outer case 5 (filter outer case 21) are provided in a three-layer structure. The side end of the heat shield case 190 is formed shorter than the side end of the outer case 21), and the side end of the catalyst inner case 4 (filter inner case 20) is formed shorter than the side end of the heat shield case 190. Therefore, the temperature drop of the exhaust gas can be reduced, and the processing efficiency of the particulate matter in the exhaust gas can be improved. An increase in the surface temperature of the catalyst outer case 5 (filter outer case 21) can be reduced, and the workability such as maintenance of the diesel engine 70 required during operation can be improved.

1 DPF (diesel particulate filter)
2 Diesel oxidation catalyst (gas purifier)
3 Soot filter (gas purifier)
4 Catalyst inner case 5 Catalyst outer case 5a Sensor mounting opening (sensor mounting hole)
20 Filter inner case 21 Filter outer case 25 Catalyst side joint flange 63 Differential pressure sensor (exhaust gas sensor)
70 Diesel engine 109 Upstream gas temperature sensor (exhaust gas sensor)
110 Sensor boss body 113 Sensor boss body

Claims (1)

An exhaust gas purifying apparatus comprising a plurality of gas purifying bodies for purifying exhaust gas discharged from an engine, a plurality of inner cases in which the gas purifying bodies are provided, and a plurality of outer cases in which the inner cases are provided. In
The flange body of one of the outer cases and the flange body of the other outer case are abutted and connected,
A heat shield case extended from one inner case to the outer surface of the other inner case is provided on the outer surface of one inner case, and the other inner case is inserted into the heat shield case. Fixing one end side of the heat shield case to the outer peripheral surface on the inner side of the end surface of the inner case, and connecting the other end side of the heat shield case to the flange body of one of the outer cases,
An exhaust gas purification apparatus characterized in that a sensor boss body for supporting an exhaust gas sensor is fixed to the outer peripheral surface of the heat shield case, and the sensor boss body is extended outward of the outer case .

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