JP2016186302A - Heat insulation cover for exhaust emission control unit, and exhaust emission control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maintainability of an exhaust emission control unit and to prevent water from being infiltrated to the inside of a heat insulation cover.SOLUTION: The heat insulation cover comprises: a horizontal piping cover 18 that is mounted in a portion of an exhaust emission control unit 1 at a vehicle front side; and a lower piping cover 15 that is detachably mounted in a portion of the exhaust emission control unit 1 at a vehicle rearer-side than the horizontal piping cover 18. A vehicle rear-side end of the horizontal piping cover 18 is covered by a vehicle front-side end of the lower piping cover 15. In a portion of the lower piping cover 15 that is covered by the horizontal piping cover 18, a rib 180B that protrudes closer to the horizontal piping cover 18 is formed in a direction that crosses a longitudinal direction of a vehicle. In the horizontal piping cover 18, a groove 18B in which the rib 180B is fitted is formed along the rib 180B.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heat insulating cover attached to an exhaust purification unit, and an exhaust purification unit.

  As an exhaust gas purification unit for reducing and purifying nitrogen compounds (NOx) in exhaust gas discharged from an internal combustion engine, a front stage portion including an oxidation catalyst and a filter for collecting particulate matter (hereinafter referred to as PM) in exhaust gas, and urea water And a rear stage portion that includes a selective reduction catalyst (hereinafter referred to as SCR catalyst) that purifies nitrogen compounds (hereinafter referred to as NOx) in exhaust gas using ammonia generated from the reducing agent as a reducing agent (for example, Patent Documents) 1).

  In the exhaust gas purification unit described in Patent Document 1, a front casing that accommodates an oxidation catalyst and a filter and a rear casing that accommodates an SCR catalyst are arranged in parallel, and an upstream end of a straight connection pipe disposed between them and The downstream ends are respectively connected to the outlet of the front casing and the inlet of the rear casing. A urea water injection device is arranged at the upstream end of the connecting pipe, and urea water is added to the exhaust gas introduced from the front casing to the rear casing, and the urea water is hydrolyzed in the exhaust gas to generate ammonia. The ammonia is supplied to the SCR catalyst as a reducing agent, so that NOx in the exhaust gas is reduced and purified.

JP 2009-36109 A

  In the exhaust purification unit described in Patent Document 1, in order to maintain the catalyst temperature at an activation temperature or higher and to promote the hydrolysis of urea water, the temperature reduction of the exhaust gas and the heat radiation from the exhaust purification device are suppressed. There is a need. Therefore, it is conceivable to cover the exhaust purification unit with a heat insulating cover, but the heat insulating cover is a thing to be removed at the time of maintenance. In addition, in order to configure the heat insulating cover so that it can be attached and detached, it is necessary to connect the covers divided into a plurality of parts with bolts or to overlap them, but from the overlapped portion of the heat insulating cover to the inside of the heat insulating cover. It is necessary to prevent water from entering.

  The disclosed heat insulation cover is intended to improve the maintainability of the exhaust purification unit and prevent water from entering the inside of the heat insulation cover.

  The heat insulation cover for the disclosed exhaust purification unit is a heat insulation cover that is attached to the exhaust purification unit that purifies the exhaust gas discharged from the internal combustion engine, and is a first part that is attached to a portion of the exhaust purification unit on the front side of the vehicle. A cover, and a second cover that is detachably attached to a portion of the exhaust purification unit on the rear side of the vehicle with respect to the first cover. A convex portion projecting toward the first cover is provided in a direction intersecting the vehicle front-rear direction at a portion of the second cover that is covered with the rear end portion of the vehicle. The first cover is formed with a recess along which the protrusion fits.

  Further, the disclosed exhaust purification unit is an exhaust purification unit including a unit main body provided in an exhaust system of an internal combustion engine for purifying exhaust gas, and a heat insulation cover attached to the unit main body, wherein the heat insulation cover includes: A first cover that is attached to a portion of the exhaust unit body on the front side of the vehicle; and a second cover that is detachably attached to a portion of the unit body that is on the rear side of the vehicle with respect to the first cover. A vehicle front side end portion of the cover is covered with a vehicle rear side end portion of the first cover, and a portion of the second cover covered by the first cover protrudes toward the first cover side. A convex portion is formed along a direction intersecting the vehicle front-rear direction, and a concave portion into which the convex portion is fitted is formed along the convex portion in the first cover.

  According to the heat insulating cover of the disclosure, it is possible to improve the maintainability of the exhaust purification unit and prevent water from entering the inside of the heat insulating cover.

It is a perspective view which shows the exhaust gas purification unit which concerns on one Embodiment from diagonally upward. It is a perspective view which shows the exhaust gas purification unit which concerns on one Embodiment from diagonally downward. It is a perspective view which shows the exhaust gas purification unit in the state with which the heat insulation cover was mounted | worn from diagonally upward. It is a perspective view which shows the exhaust gas purification unit in the state with which the heat insulation cover was mounted | worn from diagonally downward. It is sectional drawing which shows the coupling structure of a pipe horizontal cover and a pipe lower cover. It is sectional drawing which shows the state from which the piping lower cover was removed. It is sectional drawing which shows the coupling structure of the pipe horizontal cover and pipe lower cover which concern on a comparative example. It is sectional drawing which shows the coupling structure of the piping horizontal cover and piping lower cover which concern on other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an exhaust purification unit 1 according to an embodiment from obliquely above, and FIG. 2 is a perspective view showing the exhaust purification unit 1 from obliquely below. In these drawings, an exhaust purification unit (corresponding to a unit main body in claims) 1 with a heat insulating cover 10 (see FIGS. 3 and 4) removed is shown.

  The exhaust purification unit 1 includes a front casing 20, a mixer chamber 23, a urea water injection valve 30, a connection pipe 24, and a rear casing 40 in order from the exhaust upstream side.

  The front-stage casing 20 and the rear-stage casing 40 have a cylindrical shape, are arranged in parallel so that their axes are parallel to each other, and are connected by a connection pipe 24 arranged therebetween. The connection pipe 24 includes a cylindrical first pipe 24 </ b> A, and is arranged so that the axis of the pipe 24 </ b> A is parallel to the axes of the front casing 20 and the rear casing 40.

  The front-stage casing 20 includes a first casing 20A and a second casing 20B arranged coaxially on the exhaust downstream side of the first casing 20A. An annular flange is provided at the exhaust downstream end of the first casing 20A and the exhaust upstream end of the second casing 20B, and both flanges are fastened by bolts and nuts. Further, the first casing 20A contains the first oxidation catalyst 21, and the second casing 20B contains the filter 22.

  The first oxidation catalyst 21 is, for example, a catalyst component or the like supported on the surface of a ceramic carrier such as a cordierite honeycomb structure. The first oxidation catalyst 21 oxidizes unburned hydrocarbons (HC) supplied by post injection or exhaust pipe injection to raise the exhaust temperature.

  In the filter 22, for example, a large number of cells partitioned by porous partition walls are arranged along the flow direction of the exhaust gas, and the upstream side and the downstream side of these cells are alternately plugged. The filter 22 collects particulate matter (hereinafter referred to as PM) in the exhaust gas in the pores and surfaces of the partition walls, and burns PM when the estimated amount of PM deposition reaches a predetermined amount and so-called forced filter regeneration is performed. Remove. Here, the forced filter regeneration is by supplying unburned hydrocarbons to the first oxidation catalyst 21 on the exhaust upstream side by exhaust pipe injection or post injection, and raising the exhaust temperature flowing into the filter 22 to the PM combustion temperature. Done.

  The mixer chamber 23 is disposed at the exhaust downstream end of the second casing 20B, and has a first chamber 23A having an arc-shaped side surface, and a second chamber 23B having an arc-shaped side surface extending from the side surface of the first chamber 23A to the rear casing 40 side. It has. The first chamber 23A is arranged coaxially with the second casing 20B. The diameter of the second chamber 23B is smaller than the diameter of the first chamber 23A, and the boundary between both is curved in an arc shape.

  An annular flange is provided at the exhaust downstream end of the second casing 20B and the exhaust upstream end of the first chamber 23A, and both flanges are fastened by bolts and nuts.

  The connection pipe 24 includes a cylindrical first pipe 24A connected to the second chamber 23B, and a second pipe 24B that connects the first pipe 24A and the exhaust upstream end of the rear casing 40. The first pipe 24 </ b> A is arranged coaxially with the injection shaft of the urea water injection valve 30.

  The second pipe 24B is an elbow pipe, and the exhaust downstream end is formed in a disk shape. The straight portion of the second pipe 24B is arranged coaxially with the first pipe 24A, and an annular flange is provided at the exhaust downstream end of the first pipe 24A and the exhaust upstream end of the second pipe 24B. Are fastened with bolts and nuts. An annular flange is provided at the exhaust downstream end of the second pipe 24B and the exhaust upstream end of the rear casing 40, and both flanges are fastened with bolts and nuts.

  The urea water injection valve 30 is provided in the second chamber 23B. The injection shaft of the urea water injection valve 30 is aligned with the axis of the first pipe 24A, and urea water is injected (sprayed) from the urea water injection valve 30 to the exhaust downstream side of the connection pipe 24.

In the connection pipe 24, urea water injected from the urea water injection valve 30 and exhaust gas flowing from the mixer chamber 23 to the rear casing 40 are mixed, and the urea water is hydrolyzed by the exhaust heat to be ammonia (NH ₃ ). Is generated. The produced ammonia is supplied to the SCR catalyst 41 on the exhaust downstream side by the flow of the exhaust gas.

  The rear casing 40 contains an SCR catalyst 41 and a second oxidation catalyst 42 disposed on the exhaust downstream side of the SCR catalyst 41.

  The SCR catalyst 41 is, for example, one in which zeolite or the like is supported on a porous ceramic carrier. The SCR catalyst 41 adsorbs ammonia supplied as a reducing agent from the urea water injection valve 30 and selectively reduces and purifies NOx from the exhaust gas with the adsorbed ammonia.

  The second oxidation catalyst 42 is, for example, a catalyst component or the like supported on the surface of a ceramic carrier such as a cordierite honeycomb structure, and has a function of oxidizing ammonia slipped from the SCR catalyst 41 to the exhaust downstream side. doing.

  Here, the first casing 20A, the second casing 20B, and the rear casing 40 have a configuration in which a pair of semi-cylindrical members are coupled by bolts and nuts, and can be removed by releasing the fastening by the bolts and nuts. it can. At the time of maintenance, the first casing 20A, the second casing 20B, and the rear casing 40 are detached.

  FIG. 3 is a perspective view showing the exhaust purification unit 1 with the heat insulation cover 10 attached thereto obliquely from above, and FIG. 4 is a perspective view showing the exhaust purification unit 1 in this state obliquely from below. As shown in these drawings, the heat insulating cover 10 includes a chamber cover 11 that covers the entire mixer chamber 23, a front upper cover 12 that covers the upper side of the second casing 20B, and a front lower cover that covers the bottom side of the second casing 20B. Cover 13, pipe upper cover 14 covering the upper side of connection pipe 24, pipe lower cover 15 covering the bottom side of connection pipe 24, rear upper cover 16 covering the upper side of rear casing 40, and bottom side of rear casing 40 And a pipe lateral cover 18 that covers the disc-shaped portion on the exhaust downstream side of the second pipe 24B.

  The chamber cover 11 has the same shape as the mixer chamber 23 and is slightly larger in size. The chamber cover 11 is fitted to the outside of the chamber cover 11 and covers the entire chamber cover 11. The front upper cover 12 has the same shape as the upper part of the second casing 20B and is slightly larger in size, and is fitted to the upper part of the second casing 20B to cover the upper part of the second casing 20B. The front upper cover 12 includes a horizontal portion 12A extending horizontally above the first piping 24A of the connection piping 24, a flange portion 12B provided on the opposite side of the horizontal portion 12A, and a chamber cover in the vicinity of the flange portion 12B. 11 and a flange portion 12 </ b> C provided to cover 11. The flange portion 12C is fastened to the chamber cover 11 with bolts.

  The front lower cover 13 is formed so as to cover the bottom and sides of the second casing 20B and the side of the first casing 20A on the connection pipe 24 side. A bottom portion 13A of the front lower cover 13 is placed on the bottom portion of the chamber cover 11, and an overlapping portion of the front lower cover 13 and the chamber cover 11 is fastened with a bolt. A flange (not shown) is provided at the upper end of the arc-shaped portion of the front lower cover 13, and the flange and the flange portion 12 </ b> B of the front upper cover 12 are fastened with bolts.

  The pipe upper cover 14 is a rectangular flat plate disposed on the upper side of the connection pipe 24. One end in the width direction of the pipe upper cover 14 is covered with the horizontal portion 12A of the front upper cover 12, and these overlapping portions are fastened with bolts.

  The pipe lower cover 15 includes a flat bottom 15A disposed below the connection pipe 24, a semi-cylindrical curved part 15B that covers the connection pipe 24 from the lower side, and a curved part 15B on the lower side of the rear casing 40. And a horizontal portion 15C extending horizontally from the upper end of the. The bottom portion 13A of the front lower cover 13 is covered with the bottom portion 15A of the pipe lower cover 15, and these overlapping portions are fastened with bolts. Here, the pipe lower cover 15 constitutes a part of a cover that covers the front casing 20 and the rear casing 40 on the vehicle rear side of the pipe lateral cover 18.

  The rear upper cover 16 has the same shape as the upper part of the rear casing 40 and is slightly larger in size. The rear upper cover 16 is fitted to the upper part of the rear casing 40 and covers the upper part of the rear casing 40. A flange portion 16A is provided at one end portion in the circumferential direction of the rear upper cover 16, and the flange portion 16A is put on the pipe upper cover 14 and fastened with bolts.

  The rear lower cover 17 includes a bottom portion (not shown) where the bottom portion 15A of the pipe lower cover 15 is covered, and a side portion 17A that covers the lower side of the rear casing 40. The bottom of the rear lower cover 17 and the bottom 15A of the pipe lower cover 15 are fastened with bolts. Further, the upper end of the side portion 17A is put on the lower end of the rear upper cover 16, and these overlapping portions are fastened with bolts.

  The pipe horizontal cover 18 is formed in a lid shape so as to cover the exhaust downstream side portion of the connection pipe 24, and a wall 18A is formed at the peripheral edge. A bracket 19 is provided on the upper side of the pipe horizontal cover 18, and a bracket 43 is provided at the exhaust upstream end of the rear casing 40. By fastening the bracket 19 and the bracket 43 with bolts and nuts, The pipe lateral cover 18 is fixed to the rear casing 40.

  Here, as shown in FIG. 4, at one end of the curved portion 15B of the pipe lower cover 15 in the longitudinal direction (direction parallel to the connecting pipe 24), a coupling portion 180 that overlaps the wall portion 18A of the pipe lateral cover 18 is formed. Is provided. A wall portion 180 </ b> A that overlaps the wall portion 18 </ b> A is formed at the periphery of the coupling portion 180.

  FIG. 5 is a cross-sectional view showing a coupling structure between the pipe horizontal cover 18 and the pipe lower cover 15. As shown in this figure, the vehicle front side end portion of the wall portion 180 </ b> A of the coupling portion 180 is covered with the vehicle rear side end portion of the wall portion 18 </ b> A of the pipe lateral cover 18. Here, a bent rib 180B that is bent inward of the cover is formed at the tip of the wall portion 180A. The rib 180B is continuously formed at the tip of the wall portion 180A along a direction orthogonal to the vehicle longitudinal direction.

  On the other hand, a groove 18B into which the rib 180B is fitted is formed in the wall portion 18A. The groove 18B is a recess having a rectangular cross section formed continuously along the rib 180B.

  By the way, at the time of maintenance of the exhaust purification unit 1, the first casing 20A, the second casing 20B, and the rear casing 40 are removed, and the catalyst inside thereof is cleaned or replaced. Therefore, it is necessary to remove the pipe lower cover 15, the front lower cover 13, the rear lower cover 17, and the like.

  Here, the pipe lower cover 15 is combined with the pipe horizontal cover 18 and the chamber cover 11 in a state of covering (see FIG. 4). Therefore, as shown in FIG. 6, the pipe lower cover 15 can be removed with the pipe side cover 18 and the chamber cover 11 attached to the exhaust purification unit 1.

  Since the front lower cover 13 is combined with the front cover 13 while being covered with the chamber cover 11, the front lower cover 13 can be removed while the chamber cover 11 is attached to the exhaust purification unit 1. . Further, since the rear lower cover 17 is not combined with the pipe side cover 18 and the chamber cover 11, the rear lower cover 17 can be removed in a state where the chamber cover 11 is attached to the exhaust purification unit 1.

  As described above, the pipe lower cover 15, the front lower cover 13, and the rear lower cover 17 are removed from the exhaust purification unit 1 with the chamber cover 11 mounted on the exhaust purification unit 1, and the first casing 20A and the second casing are removed. 20B and the rear casing 40 can be removed and the internal catalyst can be cleaned or replaced.

  FIG. 7 is a view showing a coupling structure of the pipe horizontal cover 18 and the pipe lower cover 15 according to the comparative example. As shown in this figure, in the coupling structure according to this comparative example, the above-described rib 180B and groove 18B are not provided on the wall portions 180A and 18A, and the wall portion 180A is only covered on the wall portion 18A. It is.

  Here, the pipe lateral cover 18 is disposed at the foremost part of the exhaust purification unit 1 in the vehicle front-rear direction and receives the traveling wind W. Therefore, when it rains, rainwater hits the front surface of the horizontal pipe cover 18 and reaches the wall 18A. Since the wall portion 180A is covered with the wall portion 18A, rainwater may enter the cover from between the wall portion 18A and the wall portion 180A.

  On the other hand, as shown in FIG. 5, in the joint structure of the pipe lateral cover 18 and the pipe lower cover 15 according to the present embodiment, a rib 180B is provided at the tip of the wall part 180A that covers the wall part 18A. A groove 18B into which the rib 180B is fitted is provided in the wall portion 18A. As a result, rainwater reaching the wall portion 18A from the front surface of the pipe lateral cover 18 is blocked by the ribs 180B and the grooves 18B.

  As described above, according to the heat insulating cover 10 according to the present embodiment, the pipe lower cover 15 combined with the chamber cover 11 can be removed while the chamber cover 11 is attached to the exhaust purification unit 1, and the chamber Intrusion of rainwater into the heat insulating cover 10 due to the traveling wind W hitting the cover 11 can be prevented.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement. For example, in the above-described embodiment, the rib 180B has a shape in which the end portion of the coupling portion 180 is bent. However, as shown in FIG. 8, the rib 180B may have a shape protruding from the position of a predetermined length from the end portion.

  In the above-described embodiment, the present invention has been described by taking the exhaust purification unit including the oxidation catalyst and the SCR catalyst as an example, but the present invention is also applied to other exhaust purification units such as the exhaust purification unit including the NOx storage reduction catalyst. The invention can be applied.

DESCRIPTION OF SYMBOLS 1 Exhaust purification unit, 10 Thermal insulation cover, 11 Chamber cover, 12 Front stage upper cover, 12A Horizontal part, 12B Flange part, 12C Flange part, 13 Front stage lower cover, 13A Bottom part, 14 Piping upper cover, 15 Piping lower cover, 15A Bottom part , 15B Bent part, 15C Horizontal part, 16 Rear stage upper cover, 16A Flange part, 17 Rear stage lower cover, 17A Side part, 18 Pipe side cover, 18A Wall part, 18B Groove, 19 Bracket, 20 Front stage casing, 20A First casing , 20B second casing, 21 first oxidation catalyst, 22 filter, 23 mixer chamber, 23A first chamber, 23B second chamber, 24 connection piping, 24A first piping, 24B second piping, 30 urea water injection valve, 40 Rear casing, 41 SCR catalyst, 42 Second oxidation catalyst, 43 bracket, 180 joint, 180A wall, 180B rib

Claims (4)

A heat retaining cover attached to an exhaust purification unit for purifying exhaust gas discharged from an internal combustion engine,
A first cover attached to a vehicle front side portion of the exhaust purification unit;
A second cover that is detachably attached to a portion of the exhaust purification unit on the rear side of the vehicle relative to the first cover;
The vehicle front side end portion of the second cover is covered with the vehicle rear side end portion of the first cover,
A convex portion protruding toward the first cover is formed along a direction intersecting the vehicle front-rear direction at a portion of the second cover that is covered with the first cover.
The first cover is provided with a concave portion into which the convex portion is fitted along the convex portion. The first cover is disposed on the vehicle front side with respect to a catalyst provided in the exhaust purification unit and a casing housing the catalyst, and covers a pipe connected to the casing.
The heat insulation cover for the exhaust gas purification unit according to claim 1, wherein the second cover constitutes a part of a cover that covers the casing on a vehicle rear side with respect to the first cover. A third cover disposed on the vehicle rear side of the second cover and covering a portion of the exhaust purification unit on the vehicle rear side of the casing;
The heat insulation cover for an exhaust gas purification unit according to claim 2, wherein a vehicle rear side end portion of the second cover is covered with a vehicle front side end portion of the third cover. An exhaust purification unit comprising a unit main body provided in an exhaust system of an internal combustion engine for purifying exhaust gas, and a heat insulating cover attached to the unit main body,
The heat insulating cover is
A first cover mounted on a front side of the unit main body;
A second cover that is detachably attached to a portion of the unit body that is closer to the rear of the vehicle than the first cover;
The vehicle front side end portion of the second cover is covered with the vehicle rear side end portion of the first cover,
A convex portion protruding toward the first cover is formed along a direction intersecting the vehicle front-rear direction at a portion of the second cover that is covered with the first cover.
An exhaust purification unit in which the concave portion into which the convex portion is fitted is formed in the first cover along the convex portion.

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