JP3160356U - Engine exhaust purification system - Google Patents

Abstract

Disclosed is an engine exhaust purification device that prevents blow-by gas from being mixed in secondary air supplied to a catalyst as much as possible. An extension pipe 27 is provided in a clean side chamber 14 of the air cleaner to project a blow-by gas flowing in from an outlet 35 of a duct 31 to the engine side. A suction port 28 for supplying secondary air to the catalyst is opened at one corner of the upper portion of the clean side chamber 14. The outflow port 35 is formed at the front end portion of the duct 31 and closer to the bottom surface, and is in a positional relationship far away from the suction port 28 formed in the upper portion of the clean side chamber 14 at the back thereof. Blow-by gas is less likely to be mixed. Since the suction port 28 is located above the opening surface 27A of the extension pipe 27 and outside the opening width region of the opening face 27A, the suction force of the secondary air is affected by the suction force from the extension pipe 27. The situation of decline can be eased. [Selection] Figure 4

Description

  The present invention relates to an exhaust emission control device for an engine.

  Generally, in a system in which exhaust from an engine is processed by a purification device using a catalyst, clean secondary air is supplied to the catalyst. The following Patent Document 1 is known as such a conventional technique.

  In the structure disclosed herein, the engine side and the clean side chamber side of the air cleaner are connected by a blow-by gas extraction passage, and the secondary air is provided from the middle of the blow-by gas extraction circuit. And is supplied to the catalyst side. Therefore, both the air purified in the clean side chamber of the air cleaner and the blow-by gas are sucked into the secondary air supply passage. Blow-by gas is also processed by the catalyst, but in order to reduce the processing burden of the catalyst, a heat storage member is provided at a position immediately before the catalyst, and heat treatment is performed on the heat storage member prior to the treatment with the catalyst. .

Japanese Utility Model Publication No. 63-45535

  However, in the structure in which blow-by gas is actively taken into the catalyst as in the above-mentioned patent document, the catalyst cannot be protected from oil contamination unless an oil treatment facility such as a heat storage member is provided.

  An object of the present invention is to protect the catalyst from oil contamination by avoiding the situation where blow-by gas is mixed in the secondary air supplied to the catalyst as much as possible.

  As means for achieving the above-mentioned object, the present invention is an engine purification device provided with an exhaust purification catalyst in an engine exhaust passage, and an air cleaner to which an upstream end of an engine intake passage is connected. A secondary air passage for connecting the air cleaner and the exhaust passage to supply secondary air to the catalyst, and a blow-by gas for introducing the blow-by gas generated in the engine by connecting the engine and the air cleaner to the air cleaner The passage is characterized in that the upstream end of the secondary air passage that opens into the air cleaner and the downstream end of the blow-by gas passage that opens into the air cleaner are arranged apart from each other.

  The blow-by gas introduced into the air cleaner through the blow-by gas passage returns to the engine through the intake passage. Since blow-by gas exists inside the air cleaner, there is a concern that mist components in the blow-by gas may be mixed into the secondary air supplied to the catalyst side through the secondary air passage. However, since the part where the upstream end of the secondary air passage opens in the air cleaner is located away from the part where the downstream end of the blow-by gas passage opens, the situation of mixing mist components into the secondary air is effectively mitigated. Thus, the influence on the catalyst can be suppressed.

1 is a schematic configuration diagram of an exhaust purification device according to Embodiment 1. FIG. Plan view of air cleaner Sectional drawing which expands and shows the duct part which is a part of blow-by gas passage Front view of the cleaner case viewed from the rear of the vehicle with the cover and elements removed FIG. 4 equivalent diagram according to the second embodiment FIG. 4 equivalent diagram according to Embodiment 3 Side view of air cleaner according to embodiment 4. Schematic configuration diagram of an exhaust purification device according to Embodiment 5

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an outline of an exhaust emission control device in the present embodiment. In the figure, reference numeral 1 denotes an engine mounted on a motorcycle, which is implemented, for example, as a unit swing type that is swingably mounted on a body frame. An intake passage 2 is connected to the intake port of the engine 1. A fuel supply device 3 (a carburetor or a fuel injection) is disposed in the vicinity of the intake port of the engine 1 in the intake passage 2. An air cleaner 4 is provided at the upstream end of the fuel supply device 3 in the intake passage 2.

  An exhaust passage 5 is connected to the exhaust port of the engine 1. The downstream end of the exhaust passage 5 is connected to a muffler 6 for silencing. In the case of the present embodiment, a first catalyst 7 mainly for the purpose of reducing action is disposed in the muffler 6 and a second catalyst mainly arranged for the purpose of oxidizing action with a space 9 disposed downstream of the first catalyst 7. 8 are provided.

  The first catalyst 7 can reduce and purify NOx if the air-fuel ratio is richer than the stoichiometric air-fuel ratio. On the other hand, the second catalyst 8 has an excess of oxygen, that is, oxygen is required for combustion. If it is present in a larger amount, CO and HC can be oxidized and purified.

  In the muffler 6, one end side of an air conduit 12 constituting the secondary air passage 11 is connected to a space 9 provided between the first catalyst 7 and the second catalyst 8, that is, upstream of the second catalyst 8. Yes. The other end side (upstream end side) of the air conduit 12 is connected to the clean side chamber 14 of the air cleaner 4. A reed valve 15 functioning as a check valve is interposed in the air conduit 12. The reed valve 15 allows the secondary air to flow only from the air cleaner 4 side to the muffler 6 side, and blocks the flow in the opposite direction. Specifically, negative pressure is generated in the exhaust passage 5 due to exhaust pulsation caused by opening and closing of an intake / exhaust valve (not shown) of the engine 1. The negative pressure at this time sucks air from a clean side chamber 14 in the air cleaner 4 described later, and reaches the space 9 in the muffler 6 through the secondary air passage 11.

  The crankcase of the engine 1 is provided with a breather chamber 16 communicating with the crankcase. The breather chamber 16 is connected to the upstream end side of a blow-by gas conduit 17 constituting a blow-by gas passage. On the other hand, the downstream end side of the blow-by gas conduit 17 is connected to the air cleaner 4 and communicates with the clean side chamber 14.

  The air cleaner 4 includes a cleaner case 19, an element 18 and a cover 20. The opening surfaces of the cleaner case 19 and the cover 20 are abutted with the element 18 sandwiched therebetween, and the four corners are bolted in the abutted state. It is assembled by tightening. Thus, the interior of the air cleaner 4 is divided into two chambers with the element 18 as a boundary, one is a dirty side chamber 13 formed inside the cover 20 and into which outside air flows, and the other is formed inside the cleaner case 4A. Clean side chamber 14 into which clean air filtered by element 18 flows.

  The cleaner case 19 is formed of a synthetic resin material in a hollow box shape, and is formed so as to open to one side (the rear side when the entire air cleaner 4 is mounted on the vehicle body). That is, as shown in FIG. 4, the cleaner case 19 has vertical walls 19A to 19C on both sides in the vehicle width direction and three sides in front of the vehicle, and further has a ceiling wall 19D and a bottom wall 19E. ing.

  A portion extending from the upper part of the vertical wall 19C to the ceiling wall 19D located on one side in the vehicle width direction in the cleaner case 19 (on the right side of the vehicle when mounted on the vehicle body) to the ceiling wall 19D is provided with an overhanging portion 21 projecting inward in a substantially L shape. It has been. In the cleaner case 19, the outer surface side of the portion where the overhanging portion 21 is provided is recessed due to the provision of the overhanging portion 21, and this hollow portion is held by the covering member 22 in a state of having a space inside. It is covered (see FIG. 2). The covering member 22 opens to the front of the vehicle, and outside air enters the space surrounded by the covering member 22 through this opening.

  A rear wall 23 is provided on the front side of the overhanging portion 21, and an inlet pipe 24 for taking outside air into the dirty side chamber 13 is attached to the central portion of the rear wall 23 in a horizontal posture. It is supported at the center of the. The inlet pipe 24 is formed with a vertically long oval cross section in the vertical direction, and its front end side (the front end side of the vehicle) protrudes into the space surrounded by the covering member 22, and the front end portion has a trumpet shape. is doing. A rear end portion of the inlet pipe 24 is thrust into the dirty side chamber 13 through a relief hole 26 formed in the frame body 25 to which the element 18 is attached. The opening on the dirty side chamber 13 side in the inlet pipe 24 is formed so that the opening surface faces obliquely upward.

An extension pipe 27 that constitutes a part of the intake passage 2 for intake air to the engine 1 is supported on the vertical wall 19A located in front of the vehicle in the clean side chamber 14.
The extension pipe 27 penetrates the cleaner case 19 inward and outward in the vehicle front-rear direction, and a portion protruding forward of the vehicle is bent so as to form an arc shape in the right direction in the vehicle width direction in plan view. The end of a pipe constituting the intake passage 2 is connected to the end. On the other hand, the portion located inside the cleaner case 19 is configured as follows.
That is, the position at which the extension pipe 27 is supported on the vertical wall 19A is the central portion of the vertical wall 19A in the vehicle width direction and the height direction, and the extension pipe 27 extends obliquely upward from here. ing. This extending direction is a direction in which the secondary air is sucked away from a suction port 28 described later. In other words, the direction in which the extension pipe 27 extends in the clean side chamber 14 is an arcuate direction in a plan view as shown in FIG. 2, and the extension direction outside the cleaner case 19. Is set to be continuous with almost the same curvature. Thereby, the air sucked out from the clean side chamber 14 flows smoothly toward the engine 1 side. And the edge part in the clean side chamber 14 of the extension pipe 27 opens, The opening surface 27A has faced substantially horizontal and upwards. The opening surface 27 </ b> A is formed in an approximately elliptical shape, and the center position is slightly closer to the back (front of the vehicle) from the center in the depth direction of the clean side chamber 14.

  As shown in FIG. 4, a suction port 28 serving as an upstream end of the secondary air passage 11 is opened at the upper left corner of the vertical wall 19 </ b> A located in front of the vehicle in the clean side chamber 14 in the vehicle width direction. The force for sucking the secondary air from the suction port 28 is based solely on the negative pressure of the exhaust pulsation. The height at which the center of the suction port 28 is located is set to be higher than the height position of the opening surface 27A of the extension pipe 27 (height indicated by the line CC in FIG. 4). . This is because the blow-by gas blown up into the clean side chamber 14 is sucked from the opening surface of the extension pipe 27 so that the blow-by gas is not easily sucked from the suction port 28, as will be described later. Further, as shown in FIG. 2, the place where the suction port 28 is provided is a pedestal 29 that protrudes toward the front (rear side of the vehicle) toward the adjacent vertical wall 19 </ b> B.

  On the other hand, the portion that forms the suction port 28 protrudes into the clean side chamber 14, so that a recess is formed on the outer surface side of the portion, and the connection port 30 extends from the opening edge of the suction port 28 into the recess. Projecting toward the front of the vehicle. A pipe constituting the secondary air passage 11 is connected to the connection port 30. However, the tip of the connection port 30 is set to a length that does not protrude outward from the recess so that interference with a foreign object is avoided.

  In addition, a duct 31 extends along the depth direction at a corner connecting the vertical wall 19B on the opposite side (left side in the vehicle width direction) of the clean side chamber 14 to the bottom wall 19E. It is integrally formed. The duct 31 is for introducing blow-by gas into the clean side chamber 14. The inside of the duct 31 and the inside of the clean side chamber 14 are partitioned by an upper surface wall 31A and a side wall 31B, and both wall surfaces 31A and 31B are formed over almost the entire length of the clean side chamber 14 in the depth direction.

  As shown in FIG. 2 and the like, the back wall 32 in the duct 31 is disposed at a substantially central position in the depth direction. An inlet 33 for introducing blow-by gas into the duct 31 is opened in the back wall 32. A connecting port 34 is formed to project outward from the opening edge of the inflow port 33 along the vehicle front-rear direction, and one end of the blow-by gas conduit 17 is connected. The other end side of the conduit 17 is connected to the breather chamber 16 side. On the outer surface side of the duct 31 (the outer surface side of the cleaner case 19), the back side (vehicle front side) of the duct 31 is a recess. The above-described connecting port 34 is disposed within the length range in which the concave portion is provided, and does not protrude outward so that it does not easily interfere with foreign matter.

  The duct 31 constitutes a part of the downstream end side of the blow-by gas passage, and when the cleaner case 19 is in a single state, the front side (vehicle rear side) surface is formed so as to be entirely open. On the other hand, a portion of the frame 25 of the element 18 that faces the opening of the duct 31 is formed with a bulging portion 25A that protrudes toward the opening, as shown in FIG. The opening is closed by a closing surface 25B of the bulging portion 25A. Since the closing surface 25B is positioned opposite to the blow-by gas inlet 33 in the axial direction, the blow-by gas flowing into the duct 31 collides with the closing surface 25B. As shown in FIG. 3, a portion of the side wall 31 </ b> B constituting the duct 31 (a portion near the upper surface wall 31 </ b> A) is cut into a substantially semicircular shape at the opening edge of the duct 31, thereby flowing into the duct 31. An outlet 35 for allowing blow-by gas to flow into the clean side chamber 14 is opened.

  As a result, the outlet 35 is lower than the opening surface 27A of the extension pipe 27, and the positional relationship projected on the horizontal plane, that is, in plan view (see FIG. 2), the outlet 35 and the inlet 28 are the air cleaner 4. Are both separated in the depth direction (the longitudinal direction of the vehicle, the horizontal direction) and the vehicle width direction (the left-right direction in FIG. 4). Further, the distance D1 between the portion P1 closest to the outlet 35 in the opening surface 27A of the extension pipe 27 and the outlet 35 is equal to the portion P2 closest to the outlet 35 in the opening edge of the suction port 28. The distance D2 to the outlet 35 (both the distances D1 and D2 are distances between two points in the three-dimensional space, but in FIG. 2 and FIG. 4, both are shown in plan for convenience of illustration. ) Is shorter. The suction port 28 is located outside the projection area (area indicated by S in FIG. 2) when the opening surface 27A of the extension pipe 27 is projected onto the vertical wall 19A.

  In the duct 31, a drain hole 36 for discharging the extracted oil from the blow-by gas accumulated in the duct 31 to the outside is opened at the center in the length direction. The drain hole 36 is opened such that the lower edge portion of the opening edge substantially coincides with the bottom surface in the duct 31. From the opening edge of the drain hole 36, it protrudes to the outside of the cleaner case 19 as a discharge port 37, and a removable cap 38 is attached to the discharge port 37 to collect oil at substantially the same level as in the duct 31. be able to. The cap 38 is formed of a transparent resin material, and the accumulation of oil in the duct 31 can be visually recognized from the outside.

  The first embodiment is configured as described above. When the engine 1 is started, clean air in the clean side chamber 14 near the opening surface of the extension pipe 27 is sucked through the intake passage 2. As the exhaust from the engine 1 is performed through the exhaust passage 5, the secondary air sucked from the suction port 28 passes through the secondary air passage 11 and passes through the reed valve 15 in the middle to reach the second in the muffler 6. 1 is supplied between the second catalyst 7 and the second catalyst 8. As a result, the exhaust gas from the engine 1 is discharged to the outside air after being subjected to the purification action of both the catalysts 7 and 8. On the other hand, blow-by gas generated in the engine 1 is introduced into the air cleaner 4 through the blow-by gas conduit 17. The blow-by gas flows into the duct 31 from the inlet 33 in the air cleaner 4. At that time, the mist component adhering to the wall surface in the duct 31 flows down to the bottom surface and flows out from the drain hole 36 into the cap 38. The user can visually recognize the state of accumulation in the cap 38, remove the cap 38 at an appropriate time, and extract the oil accumulated in the duct 31.

  As described above, blow-by gas removes oil to some extent in the process of passing through the duct 31, and then blows out into the clean side chamber 14 from the outlet 35 under the circumstances. At this time, the suction port 28 and the outflow port 35 are positioned substantially at the upper and lower ends in the clean side chamber 14, and the front end and the back side are also provided in the longitudinal direction of the vehicle (the depth direction of the clean side chamber 14). As the end portion is arranged far away, blow-by gas is hardly sucked from the suction port 28. Therefore, the influence on the catalysts 7 and 8 can be avoided as much as possible.

The following technical ideas can be extracted from the first embodiment.
(A) An extension pipe 27 that constitutes a part of the intake passage 2 of the engine 1 and has an open end projects from the air cleaner 4, and from the opening (outlet 35) at the downstream end of the blow-by gas passage, The distance (D1 dimension shown in FIGS. 2 and 4) from the opening 27A of the extension pipe 27 to the portion P1 closest to the opening (outlet 35) at the downstream end of the blow-by gas passage is downstream of the blow-by gas passage. Distance from the end opening (outlet 35) to the portion P2 closest to the downstream end opening (outlet 35) of the blow-by gas passage in the upstream end opening (suction port 28) of the secondary air passage ( In this configuration, the position of the opening 27A of the extension pipe 27 is set so as to be shorter than the dimension D2 shown in FIGS.

  In the above configuration, the distance (D1 dimension) from the opening of the blow-by gas passage (outlet 35) to the opening of the extension pipe 27 reaches the opening at the upstream end of the secondary air passage. Therefore, the blow-by gas blown into the air cleaner from the opening of the blow-by gas passage (outflow port 35) is sucked in preference to the opening of the extension pipe 27. In addition, coupled with the fact that the suction force by the extension pipe 27 is larger than the suction force from the secondary air passage, it is effective for avoiding the introduction of blow-by gas into the secondary air passage.

  (B) The projecting direction of the extension pipe 27 is configured to be substantially away from the upstream end opening (suction port 28) of the secondary air passage.

  Due to the large negative pressure generated by driving the engine, the purified air in the air cleaner is sucked into the opening of the intake passage with a large suction force. On the other hand, since the suction force of the secondary air sucked through the secondary air passage is based on the negative pressure of the exhaust pulsation, which is smaller than the engine negative pressure, the opening of the secondary air passage and the intake passage Depending on the positional relationship with the opening, there may be a problem in the supply of secondary air to the catalyst. On the other hand, if the projecting direction of the extension pipe is set in a direction substantially away from the opening of the secondary air passage so as to eliminate the influence of the engine negative pressure as much as possible, the secondary air from the secondary air passage will be removed. Suction is ensured.

(C) In the air cleaner 4, a portion where the downstream end of the blow-by gas passage opens (outflow port 35) is positioned below a portion where the upstream end of the secondary air passage opens (suction port 28). .
In general, blowby gas containing a mist component has a higher specific gravity than air. Therefore, if the opening part (outflow port 35) of the blow-by gas passage is arranged at the lower position and the opening part (suction port 28) of the secondary air passage is arranged at the upper position, it is possible to avoid mixing mist into the secondary air passage. It is valid.

(D) In the positional relationship projected with respect to the horizontal plane, the portion where the downstream end of the blow-by gas passage opens (outflow port 35) and the portion where the upstream end of the secondary air passage opens (suction port 28) are horizontal. It is the structure which is spaced apart in the direction.
In other words, even if the portion where the downstream end of the blow-by gas passage opens and the portion where the upstream end of the secondary air passage opens are separated in the horizontal direction, it is effective for avoiding the mixing of mist in the secondary air passage. .

  (E) In the air cleaner 4, a duct 39 that constitutes a part of the blow-by gas passage and can extract mist oil from the blow-by gas is away from the opening portion (suction port 28) at the upstream end of the secondary air passage. This is a structure in which an opening (outflow port 35) at the downstream end of the blow-by gas passage is provided at the end of the duct 39 in the length direction.

  If comprised as mentioned above, since mist oil is extracted in a blowby gas in a duct and it introduce | transduces in an air cleaner after that, mixing of the mist component to a secondary air path can be eased. Thus, the opening of the blow-by gas passage can be moved away from the opening of the secondary air passage using the duct for extracting mist oil from the blow-by gas. Moreover, since the structure for extracting the mist oil from the blow-by gas is provided using the internal space of the air cleaner, it is not necessary to set a special structure for extraction.

  (F) The opening (suction port 28) at the upstream end of the secondary air passage is provided on the wall surface in the air cleaner 4, and the duct 39 is provided so as to extend along a direction orthogonal to the wall surface. .

  According to said structure, the opening of a secondary air path and the opening of a blow-by gas path can be spaced apart perpendicularly | vertically with respect to a wall surface using a duct.

  (G) The opening of the secondary air passage (suction port 28) is provided on the wall surface in the air cleaner 4, while the opening 27A at the tip of the extension pipe 27 is projected onto the wall surface when the opening of the secondary air passage is opened. The (suction port 28) is configured to be located outside the projection region of the opening 27A of the extension pipe 27.

  If the opening of the secondary air passage is set so as to be located outside the projection region of the opening of the extension pipe, the influence of the suction to the intake passage is further eliminated and the supply of the secondary air to the secondary air passage is performed. It becomes more effective in securing the amount.

(H) The height position of the opening 27A of the extension pipe 27 is such that the downstream end of the blow-by gas passage opens (outlet 35) and the upstream end of the secondary air passage opens (suction port 28). It is the structure provided between.
Even if blow-by gas is blown up into the air cleaner from the opening of the blow-by gas passage, the blow-by gas is sucked from the intake passage due to a large engine negative pressure and mixed into the opening of the secondary air passage higher than this. Can be relaxed.

  (I) The opening 27A of the extension pipe 27 is formed so as to face upward.

  Since the extension pipe 27 is opened upward in the air cleaner 4, the blow-by gas is located above the opening portion 27A of the extension pipe 27, that is, around the upstream end opening (suction port 28) of the secondary air passage. Even if it blows up into the space, it is captured and mixed into the secondary air passage.

(J) The opening (suction port 28) and the extension pipe 27 at the upstream end of the secondary air passage are provided on the same wall surface in the air cleaner 4 and extend when the wall surface is viewed from the direction perpendicular to the wall surface. The pipe 27 is configured to extend obliquely in a direction away from the upstream end opening (suction port 28) of the secondary air passage.
Outside the air cleaner, when the secondary air passage and the intake passage for the engine are brought closer, the piping around the air cleaner is consolidated, and space efficiency is improved. In that case, the opening of the secondary air passage and the base of the extension pipe are arranged close to each other in the clean side room. However, if the extension pipe protrudes obliquely, it extends from the opening of the secondary air passage. The opening of the tube can be easily moved away.

  (K) At least an opening of the secondary air passage is provided on a wall surface in the air cleaner, and in the positional relationship projected onto the wall surface, the opening of the secondary air passage is the same as the opening of the blow-by gas passage. A part of the extension pipe overlaps on the axis connecting the two and is disposed at a position adjacent to the base of the extension pipe.

  When the opening of the secondary air passage is viewed from the opening of the blow-by gas passage, the opening of the secondary air passage is located on the back side of the extension pipe, so the extension pipe functions as a blow-by gas shielding member. This is effective in reducing the mixing of blow-by gas into the next air passage.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the inlet port 28 for the secondary air is provided near the ceiling wall 19D of the clean side chamber 14, and the outlet port 35 for the blowby gas is provided near the bottom wall 19E. A sufficient height difference from the outlet 35 is utilized to mitigate the situation where blow-by gas is mixed into the secondary air supplied to the catalyst.

  However, in the second embodiment, the extension pipe 27 protruding into the clean side chamber 14 is used as a shielding wall against blow-by gas, not due to the height difference. Specifically, when the secondary air suction port 28A is provided in the vertical wall 19A, the extension tube 27 overlaps with a straight line connecting the blow-by gas outlet 35 at a position near the extension tube 27. I have to.

  The distance D3 (distance between two points in the three-dimensional plane) between the portion P3 closest to the outflow port 35 and the outflow port 35 in the opening surface 27A of the extension pipe 27 is the opening edge of the suction port 28A. The point which is shorter than the distance D2 (distance between two points in the three-dimensional plane) between the portion P4 closest to the outlet 35 and the outlet 35 is the same as in the first embodiment.

  As described above, since the suction port 28A is positioned almost directly behind the extension pipe 27 with respect to the flow direction of the blow-by gas, the suction of the blow-by gas from the suction port 28A hardly occurs. Further, since the suction port 28A is disposed in the vicinity of the extension pipe 27, there is a concern about the influence of the suction force from the extension pipe 27. Therefore, the arrangement is lower than the height of the opening surface of the extension pipe 27. is there.

  Since other configurations are the same as those of the first embodiment, the same reference numerals are given in the drawings, and description thereof is omitted.

<Embodiment 3>
FIG. 6 shows Embodiment 3 of the present invention. In this embodiment, the duct 39 is disposed below the overhanging portion 21. As in the second embodiment, the positional relationship between the suction port 28B and the outflow port 35 is such that the extension pipe 27 exists on a straight line connecting these. The distance D5 (distance between two points in the three-dimensional plane) between the portion P5 closest to the outlet 35 in the opening surface 27A of the extension pipe 27 and the outlet 35 is the opening edge of the suction port 28B. The point which is made shorter than the distance D6 (distance between two points in the three-dimensional plane) between the part P6 closest to the outlet 35 and the outlet 35 is the same as in the first embodiment.

  In the second embodiment, the extension pipe 27 is disposed closer to the outflow port 35. However, if the arrangement of the present embodiment is adopted, the distance between the extension pipe 27 and the inflow port 33A is widened. This is more effective for avoiding mixing of blow-by gas away from the outlet 35.

The following technical ideas can be extracted from the second and third embodiments. That is, at least the opening of the secondary air passage (suction ports 28A, 28B) is provided on the wall surface in the air cleaner 4, and the opening of the secondary air passage (suction ports 28A, 28B) in the projected position relative to the wall surface. ) Is located at a position where a part of the extension pipe 27 overlaps and is adjacent to the base of the extension pipe 27 on the axis connecting the opening (suction inlets 28A, 28B) and the opening (outlet 35) of the blow-by gas passage. It is the composition which is arranged.
With such a configuration, when the secondary air passage opening (suction ports 28A, 28B) is viewed from the blow-by gas passage opening (outlet 35), the secondary air passage openings (suction ports 28A, 28B). ) Is located on the back side of the extension pipe 27, and the extension pipe 27 functions as a blow-by gas shielding member, which is effective in mitigating the mixing of blow-by gas into the secondary air passage.

<Embodiment 4>
For example, what is shown in Unexamined-Japanese-Patent No. 2006-220019 is conventionally known as what provided the reed valve in the exhaust gas purification device. In general, the reed valve has been independently mounted on the body frame or the like away from the air cleaner. Therefore, a member for mounting the reed valve has to be provided at an appropriate place.

  In Embodiment 4 shown in FIG. 7, a reed valve 15 that is interposed in the middle of the secondary air passage 11 and allows the flow direction of the secondary air only in the catalyst direction is mounted on the outer surface of the air cleaner 4. In this way, since the reed valve 15 can be mounted using the air cleaner 4, it is not necessary to set a special member for mounting the reed valve 15.

  Specifically, the mounting portion 40 for mounting to the reed valve 15 is the outer surface of the vertical surface 41 on the left side in the vehicle width direction (the side where the duct is provided) of the cleaner case 19 and the front end surface in the vehicle front-rear direction. Is formed. The mount portion 40 is provided at a position slightly retracted inward in the vehicle width direction from the outer surface of the vertical surface 41 and is formed in a thick plate shape protruding toward the front of the vehicle. Here, although not shown in detail, a pair of upper and lower bolt holes are provided therethrough.

  The reed valve 15 has a bracket portion 15B on the outside of the valve main body portion 15A, and the reed valve 15 as a whole is attached by tightening bolts into the bolt holes (not shown) in the bracket portion 15B. Yes. In this embodiment, consideration is given to keeping the mounting state of the reed valve 15 as compact as possible.

  In the vehicle front-rear direction, the reed valve 15 is mounted so as to be within the projecting range of the extension pipe 27 that is disposed adjacent to the mounting location and projects forward of the vehicle. With respect to the vertical direction, the cleaner case 19 is mounted so as to be within the vertical height range. In the vehicle width direction, as described above, the mounting position of the mount portion 40 is formed in a state where the step 42 is provided inwardly by one step from the outer surface of the vertical surface 41. And the cover 20 are not projected in the vehicle width direction from the outer edges of the flanges 19A and 20A.

Other configurations are the same as those in the first to third embodiments.
In short, the engine purification apparatus of this embodiment includes an exhaust purification catalyst in the exhaust passage of the engine, and connects the air cleaner, the clean side chamber, and the catalyst to the catalyst. A secondary air passage for supplying secondary air, and a reed valve interposed in the middle of the secondary air passage and allowing the flow of secondary air in the secondary air passage only to the catalyst side, and The reed valve is mounted on the air cleaner.

The air cleaner 4 may be integrally formed with a mount portion 40 for attaching a reed valve.
An extension pipe 27 to which the intake passage 2 for the engine is connected protrudes from the air cleaner 4, and at least a part of the reed valve 15 is overlapped with the extension length range of the extension pipe 27. May be.

  The reed valve 15 may be at least partially overlapped with the height range of the air cleaner 4. Further, at least a part of the reed valve 15 may overlap with the length range of the air cleaner 4 in the vehicle width direction.

<Embodiment 5>
FIG. 8 shows Embodiment 5 of the present invention. In the first embodiment, the downstream end of the secondary air passage is connected between the first catalyst 7 and the second catalyst 8 with respect to the muffler 6. Although this connection position was shown to be closer to the first catalyst 7 in FIG. 1 showing the first embodiment, the configuration at that point is further clarified in FIG.

  In the muffler 6, one end side of the air conduit 12 constituting the secondary air passage 11 is connected to the space 9 provided between the first catalyst 7 and the second catalyst 8, that is, the upstream side of the second catalyst 8. A secondary air inlet 43 is opened in the space 9 described above. The positional relationship between the secondary air inlet 43 and the first and second catalysts 7 and 8 is closer to the first catalyst 7 on the upstream side with respect to the exhaust flow direction (from the center of the secondary air inlet 43 to the first When the distance to the end of the catalyst 7 is L1, and the distance to the second catalyst 8 is L2, the relationship is L1 <L2.

  Other configurations are the same as those of the first embodiment, and thus the same functions and effects can be exhibited. However, the functions and effects to be emphasized in the present embodiment are as follows.

  When the secondary air flows between the first and second catalysts 7 and 8 through the secondary air inlet 43, normally, the secondary air is exclusively along the exhaust flow along the second catalyst 8. It is thought that it flows to the side. However, in reality, under the influence of exhaust pulsation, the secondary air also moves back and forth in the space 9 in the normal flow direction and the reverse flow direction of the exhaust gas. In particular, since the secondary air inlet 43 is disposed closer to the first catalyst 7, the exhaust tends to come into contact with the first catalyst 7 during the reverse flow. Then, an oxidizing action is also performed on the downstream end side of the first catalyst 7. That is, the first catalyst 7 can assist the oxidizing action originally performed by the second catalyst 8. This is particularly true even when the second catalyst 8 has not reached the activation temperature, such as when the engine 1 is cold (before completion of the warm-up operation). Since 7 reaches the activation temperature sooner, the auxiliary oxidation action by the first catalyst 7 is extremely effective for exhaust purification.

Further, when there is a high possibility that oil will be mixed into the secondary air passage 11 as in the prior art, there is a concern that the oil will adhere to the downstream side of the first catalyst 7 and reduce the above-described oxidation action. In particular, since the location where the oil component adheres to the noble metal in the first catalyst 7 is a location that is a “shade of the flow” for the flow of exhaust gas, the oil component is unlikely to peel off, and the state of reduced oxidation action continues. There is a fear. However, in this embodiment, since mixing of oil in the secondary air is avoided, the oxidizing action by the first catalyst 7 can be maintained for a long time.
It should be noted that the effects of the fifth embodiment described above can also be exhibited in the first embodiment as long as the same configuration as that of the first embodiment is disclosed in FIG. 1 showing the first embodiment.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In the first embodiment, the case where two types of catalysts 7 and 8 are provided in the muffler 6 is shown, but one type of catalyst may be used. Further, the catalyst is not necessarily arranged inside the muffler 6 and may be arranged outside.

  (2) In any of the embodiments, the structure in which the extending pipe 27 protrudes into the clean side chamber 14 is shown. However, this protruding structure is eliminated, and only the opening leading to the intake passage of the engine is provided in the vertical wall 19A. It may be a structure.

  (3) The extending direction of the extending pipe 27 in the clean side chamber 14 is not limited to the oblique direction, and may extend straight along the depth direction. Conversely, the blow-by gas duct 31 is not formed along the depth direction, but may have a structure extending obliquely.

  (4) Although the first and second catalysts 7 and 8 are both installed in the muffler 6 in the fifth embodiment, the first catalyst 7 may be arranged near the engine 1 on the upstream side of the muffler 6. Also in that case, the connection position of the downstream end of the secondary air passage 11 is in the vicinity of the downstream side of the first catalyst 7. In this way, the degree of freedom of arrangement of the first catalyst 7 can be increased, and the oxidation action by the first catalyst 7 can be received at a position where the exhaust temperature is higher, so that the oxidation function for the exhaust can be further enhanced. it can.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake passage 4 ... Air cleaner 5 ... Exhaust passage 7, 8 ... 1st, 2nd catalyst 11 ... Secondary air passage 13 ... Dirty side chamber 14 ... Clean side chamber 15 ... Reed valve 16 ... Breather chamber 27 ... Extension pipe 28, 28A, 28B ... Suction port 31, 39 ... Duct 35 ... Outlet

Claims (14)

An exhaust purification device for an engine comprising an exhaust purification catalyst in an exhaust passage of the engine,
An air cleaner to which an upstream end of the intake passage of the engine is connected;
A secondary air passage for connecting the air cleaner and the exhaust passage to supply secondary air to the catalyst;
A blow-by gas passage for connecting the engine and the air cleaner to introduce blow-by gas generated in the engine into the air cleaner;
An exhaust emission control device for an engine, wherein an upstream end of the secondary air passage that opens into the air cleaner and a downstream end of the blow-by gas passage that opens into the air cleaner are spaced apart from each other.   A plurality of the exhaust purification catalysts are spaced apart from each other in the exhaust passage, and the secondary air passage is connected between the plurality of catalysts in the exhaust passage. Item 2. An exhaust emission control device for an engine according to Item 1.   The engine exhaust purification according to claim 2, wherein the connection position of the secondary air passage to the exhaust passage is closer to the catalyst located upstream in the exhaust flow direction of the plurality of catalysts. apparatus. In the air cleaner, an extending pipe that constitutes a part of the intake passage of the engine and that opens at the tip protrudes, and
The distance from the opening at the downstream end of the blowby gas passage to the portion closest to the opening at the downstream end of the blowby gas passage among the openings of the extension pipe is from the opening at the downstream end of the blowby gas passage, The position of the opening of the extension pipe is set to be shorter than the distance from the opening at the upstream end of the secondary air passage to the portion closest to the opening at the downstream end of the blow-by gas passage. The exhaust emission control device for an engine according to claim 1.   5. The engine exhaust gas purification apparatus according to claim 4, wherein a protruding direction of the extension pipe is a direction substantially away from the opening at the upstream end of the secondary air passage.   2. The engine exhaust gas purification apparatus according to claim 1, wherein a portion where the downstream end of the blow-by gas passage is opened in the air cleaner is positioned below a portion where the upstream end of the secondary air passage is opened. 3. .   The position where the downstream end of the blow-by gas passage opens and the portion where the upstream end of the secondary air passage opens in the positional relationship projected with respect to the horizontal plane are separated in the horizontal direction. The exhaust emission control device for an engine according to claim 1 or 4.   In the air cleaner, a duct that constitutes a part of the blow-by gas passage and can extract mist oil from the blow-by gas extends in a direction away from the opening portion at the upstream end of the secondary air passage. The engine exhaust gas purification apparatus according to claim 1, wherein an opening at a downstream end of the blow-by gas passage is provided at an end portion in a length direction.   The opening at the upstream end of the secondary air passage is provided on a wall surface in the air cleaner, and the duct is provided to extend along a direction orthogonal to the wall surface. The engine exhaust gas purification apparatus as described.   The opening of the secondary air passage is provided on a wall surface in the air cleaner, while the opening of the secondary air passage is projected onto the wall surface when the opening portion at the tip of the extension tube is projected onto the wall surface. 5. The engine exhaust gas purification apparatus according to claim 4, wherein the engine exhaust gas purification apparatus is located outside a projection region of the opening of the engine.   In the air cleaner, an extension pipe that forms a part of the intake passage of the engine and has a tip opened is provided, and the height position of the opening of the extension pipe is located downstream of the blow-by gas path. The engine exhaust gas purification apparatus according to claim 6, wherein the engine exhaust gas purification apparatus is provided between a portion where the end opens and a portion where the upstream end of the secondary air passage opens.   The engine exhaust purification device according to claim 4, wherein the opening of the extension pipe is formed facing upward.   The opening at the upstream end of the secondary air passage and the extension pipe are provided on the same wall surface in the air cleaner, and when the wall surface is viewed from a direction perpendicular to the wall surface, the extension pipe is the secondary pipe. 6. The exhaust emission control device for an engine according to claim 5, wherein the exhaust gas purification device extends obliquely in a direction away from the opening at the upstream end of the air passage.   At least an opening of the secondary air passage is provided on a wall surface in the air cleaner, and the opening of the secondary air passage connects the opening and the opening of the blow-by gas passage in a positional relationship projected onto the wall surface. The engine exhaust gas purification apparatus according to claim 4, wherein a part of the extension pipe overlaps on an axis and is disposed adjacent to a base portion of the extension pipe.

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