JP5062083B2 - Engine exhaust system - Google Patents

Description

  In the present invention, an exhaust device of an engine (internal combustion engine) that performs exhaust purification with a catalyst, particularly, immediately after a cold start in which the main catalyst is not activated, guides the exhaust to the bypass flow path provided with another catalyst. It relates to the improvement of the exhaust system of the type.

  Patent Document 1 is interposed in an upstream main passage for each cylinder connected to each cylinder, a downstream main passage formed by joining the upstream main passages of a plurality of cylinders, and the downstream main passage. An exhaust system is disclosed that includes a main catalyst, branches from an upstream main passage, and has a bypass passage in which a bypass catalyst is interposed.

  Further, each of the flow path switching valves for allowing the exhaust discharged from each cylinder to flow to the bypass passage when cold and for allowing the exhaust to flow to the upstream main passage after the warm-up of the main catalyst is completed. It is provided in the upstream main passage.

  Here, the two flow path switching valves are attached to a common valve support. The valve support body is integrally formed with an arm portion to which at least two valve bodies are assembled. Each valve body has a valve main body portion and a valve shaft portion standing up from the valve main body portion. The valve opening is opened and closed when the peripheral edge of the valve abuts and leaves the valve seat at the upstream end of the valve opening.

In addition, the arm portion is formed with a through hole into which the valve shaft portion is loosely fitted, and the tip portion of the valve shaft portion that protrudes through the through hole to the opposite side of the valve body portion is more than the through hole. A holding ring having a large outer diameter is fixed, and at least two valve bodies assembled to the arm portion are configured to open to the upstream side of the upstream main passage.
JP 2008-8284 A

  By the way, as shown in the pattern 2 of FIGS. 9 and 10, the flow path switching valve of Patent Document 1 includes a plurality of valve bodies (24 </ b> A) that open and close a plurality of valve openings formed side by side in the housing. 24B) are attached to independent valve supports (25n, 25f) for each valve body, and each valve support (25n, 25f) is integrated with a rotating shaft (23) rotatably supported on the housing side. In addition, an axially rotating shaft portion (25An, 25Af) includes an arm portion (25Bn, 25Bf) in which at least two valve bodies (24A, 24B) are assembled integrally for each valve body. it is conceivable that. That is, in the technique of Patent Document 1, the two valve bodies (24A, 24B) assembled to the arm portions (25Bn, 25Bf) are aligned in the axial direction of the rotating shaft 23 to rotate the rotating shaft (23). Is applied only to the left end (one end) of the rotating shaft (23), and the valve body (24B) farther from the left end of the rotating shaft (23) is the rotating shaft in the rotating direction of the rotating shaft (23). The arm portion (25Bf) to which the valve body (24B) far from the left end of the rotating shaft (23) is assembled so as to be relatively closer to the valve opening than the valve body (24A) closer to the left end of (23). ) And the arm portion (25Bn) to which the (valve body 24A) on the side close to the left end of the rotating shaft (23) is provided, and when there is a request to close the flow path switching valve, the driving force To drive the rotating shaft (23) in the valve closing direction and rotate The valve body (24B) on the side farthest from the left end of (23) is first seated on the valve seat portion, and in this state, rotation is performed by applying a further constant driving force in the valve closing direction to the rotating shaft (23). In the portion from the left end of the shaft (23) to the second position b, deformation in the twisting direction due to creep (this deformation in the twisting direction due to creep is hereinafter simply referred to as “twisting deformation”) is generated, and this rotating shaft (23). As a result of the torsional deformation of the portion from the left end to the second position b, the valve body (24A) on the side close to the left end of the rotating shaft (23) is seated on the valve seat portion, thereby two valve bodies (24A, 24B). ) Are both seated on the valve seat.

  Here, when thinking again, in order to keep the flow path switching valve in a fully closed state when the engine is cold started, the rotation is continued by applying a certain amount of driving force in the closing direction to the rotating shaft (23). The portion from the left end of the shaft (23) to the second position b is torsionally deformed, and the main catalyst is activated to drive the rotating shaft (23) in the opening direction so that the flow path switching valve is fully opened. For example, the portion from the left end of the rotating shaft (23) to the second position b returns to the initial state before the torsional deformation. Such torsional deformation and the return to the initial state before the torsional deformation utilize the characteristics of the material constituting the rotating shaft (23), but the torsional deformation and the initial state before the torsional deformation Problems may arise when the number (frequency) of return is increased. That is, if the engine is used for a long period of time, it repeats from the left end of the rotating shaft (23) on which the driving force acts to the second position b, torsional deformation and to the initial state before the torsional deformation. There is a risk that the material of the portion from the left end of the rotating shaft (23) to the second position b will eventually become fatigued and the portion may be broken.

  In order to prevent such breakage in the portion from the left end of the rotating shaft (23) to the second position b, that is, in order to ensure long-term reliability of the rotating shaft (23), the material of the rotating shaft 23 is: It is to adopt a material that is excellent in creep resistance (a property that is difficult to creep).

  However, excellent creep resistance means that the material is not easily twisted and deformed. Therefore, when the rotary shaft (23) is made of a material excellent in creep resistance, the second axis from the left end of the rotary shaft (23) is fully closed. As a result of the amount of torsional deformation up to the position b being smaller than the amount of torsional deformation of the material used in the conventional apparatus, the valve body (24A) on the side near the left end of the rotating shaft (23) is incomplete. There may be situations where you are not seated.

  Therefore, an object of the present invention is to provide an apparatus that can ensure the sealing performance even if the rotating shaft is made of a material having excellent creep resistance.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an upstream main passage (2) for each cylinder connected to each cylinder, a downstream main passage (3) formed by joining the upstream main passages (2) of a plurality of cylinders, and the upstream The upstream main passage (2) is opened and closed so that the bypass passages (11, 14) branch from the side main passage (2) and the exhaust gas discharged from each cylinder flows to the bypass passages (11, 14). And a flow path switching valve (4) that shuts off communication between the upstream main passages (2) when closed, and the flow path switching valve (4) is formed in parallel with the housing (21). A plurality of valve bodies (24) that respectively open and close the valve openings (51) are attached to at least one common valve support (25), and the one valve support (25) is located on the housing (21) side. 1 rotating shaft (23) rotatably supported by One arm portion (25B) to which the at least two valve bodies (24) are assembled is integrally formed with one shaft portion (25A) that rotates integrally, and each valve body (24) is a valve. It has a main body part (26) and a valve shaft part (28) standing up from the valve main body part (26), and a peripheral edge (26A) of the valve main body part (26) is an upstream end of the valve opening part (51). The valve opening (51) is opened and closed by coming into contact with and detaching from the valve seat portion (52), and the one arm portion (25B) is perpendicular to the axis of the valve shaft portion (28). A through hole (27) into which the valve shaft portion (28) is loosely fitted is formed by having a predetermined first gap in the through hole, and projects through the through hole (27) to the opposite side of the valve main body portion (26). A retaining ring (29) having an outer diameter larger than that of the through hole (27) is provided at the tip of the valve shaft portion (28). There is at least two valve bodies (24) that are fixed between the one arm portion (25B) and the valve body (26) leaving a predetermined second gap and assembled to the one arm portion (25B). In the engine exhaust system configured to open to the upstream side of the upstream main passage (2), at least two valve bodies (24) assembled to the one arm portion (25B) are connected to the rotating shaft (23). ), The driving force for rotating the rotating shaft (23) is applied to only one end of the rotating shaft (23), and the first arm is rotated in the rotating direction of the rotating shaft (23). Of the at least two valve bodies (24) assembled to the portion (25B), the first valve body (24A), which is the valve body on the side close to one end of the rotating shaft (23) on which the driving force acts, is driven. Of the rotating shaft (23) on which the force acts An arm portion (25B) to which the first valve body (24A) is assembled so as to be relatively closer to the valve opening (51) than the second valve body (24B) which is a valve body far from one end; An angle difference is provided between the second valve body (24B) and the arm portion (25B) to which the second valve body (24B) is assembled, and when there is a valve opening request for the flow path switching valve (4), the rotational force ( 23) is driven in the opening direction to bring the second valve body (24B) into contact with the stopper (55), so that the flow path switching valve (4) is fully opened and the flow path switching valve (4 ) In the fully open state, a further constant driving force is continuously applied to the rotating shaft (23) in the valve opening direction, and when there is a request for closing the flow path switching valve (4) thereafter, the driving force The rotary shaft (23) is driven in the valve closing direction.

  The present invention also provides an upstream main passage (2) for each cylinder connected to each cylinder, a downstream main passage (3) formed by joining the upstream main passages (2) of a plurality of cylinders, The bypass main passage (2) branched from the upstream main passage (2) and the upstream main passage (2) are opened and closed so that the exhaust discharged from each cylinder flows to the bypass passage (11, 14). And a flow path switching valve (4) that shuts off communication between the upstream main passages (2) when closed, and the flow path switching valve (4) is formed side by side with the housing (21). A plurality of valve bodies (24A, 24B) that respectively open and close the plurality of valve openings (51) are attached to independent valve supports (25n, 25f) for each valve body, and the valve supports (25n) for each valve body 25f) can be rotated to the housing (21) side The arm portions (25Bn, 25Bf) to which the at least two valve bodies (24A, 24B) are assembled are integrally formed on the shaft portions (25An, 25Af) that rotate integrally with the rotating shaft (23) supported by the shaft. Each valve body (24) has a valve main body (26) and a valve shaft (28) standing up from the valve main body (26). 26A) abuts on and disengages from the valve seat (52) at the upstream end of the valve opening (51), thereby opening and closing the valve opening (51), and arm portions (25Bn, 25Bf) for each valve body. A through hole (27) into which the valve shaft portion (28) is loosely fitted is formed by having a predetermined first gap in a direction perpendicular to the axis of the valve shaft portion (28). The through hole (27 ) Through the valve main body (26) and projecting to the opposite side of the valve stem (28) A retaining ring (29) having an outer diameter larger than that of the through hole (27) is provided between the arm portion (25Bn, 25Bf) and the valve main body (26) for each valve body. The structure is such that at least two valve bodies (24A, 24B) which are fixed with two gaps and are assembled to the arm portions (25Bn, 25Bf) for each valve body open to the upstream side of the upstream main passage (2). In the exhaust system of the engine, the at least two valve bodies (24A, 24B) assembled to the arm portions (25Bn, 25Bf) for each valve body are aligned in the axial direction of the rotary shaft (23), and the rotation The driving force for rotating the shaft (23) is applied only to one end of the rotating shaft (23), and the rotating direction of the rotating shaft (23) is assembled to the arm portion (25Bn, 25Bf) for each valve body. Is Of the at least two valve bodies (24A, 24B), the first valve body (24A), which is the valve body closer to one end of the rotating shaft (23) on which the driving force acts, is more acted on by the driving force. The first valve body (24A) is assembled so as to be relatively closer to the valve opening (51) than the second valve body (24B), which is a valve body far from one end of the rotating shaft (23). An angle difference is provided between the arm part (25Bn) and the arm part (25Bf) to which the second valve body (24B) is assembled, and when there is a request to open the flow path switching valve (4), the drive The rotary shaft (23) is driven in the opening direction by force to bring the second valve body (24B) into contact with the stopper (55), thereby opening the flow path switching valve (4). How to open the rotary shaft (23) when the flow path switching valve (4) is fully open Further continuing adding a constant driving force, when there is a closing request subsequent to said passage switching valve (4), said rotationally driven shaft (23) in the valve closing direction by the driving force.

Further, according to the present invention, the exhaust passage of the engine is a downstream side in which the upstream main passage (2) for each cylinder connected to each cylinder of the engine and the upstream main passage (2) for each cylinder merge. The main passage (3) and the bypass passages (11, 14) branched from the upstream main passage (2) are configured so that the exhaust discharged from each cylinder flows to the bypass passages (11, 14). And a plurality of flow path switching valves (4) in which the respective upstream main passages (2) are opened and closed by the driving force of the drive device, and the plurality of flow path switching valves (4) include at least two valve bodies ( 24A, 24B) to open and close by the driving device, the rotating shaft (23) orthogonal to the upstream main passage (2) and extending from the driving device, and at least provided on the rotating shaft (23) Two valve supports (2 n, 25f), and the at least two valve bodies (24A, 24B) move at a predetermined interval in a direction perpendicular to the rotation axis (23) with respect to the at least two valve support bodies (25n, 25f). In the exhaust gas purifying apparatus of the engine that can be attached, the valve support (25n) closer to the drive unit among the at least two valve supports (25n, 25f) is more than the valve support (25f) far from the drive unit. An angle difference is provided so as to be relatively close to the seating position of the flow path switching valve in the upstream main passage (2), and when there is a request to open the flow path switching valve (4), the driving force The rotary shaft (23) is driven in the opening direction to bring the valve body (24B) far from the driving device into contact with the stopper (55), so that the flow path switching valve (4) is fully opened. Road cut Wherein in the fully open state of the valve (4) rotation axis (23) continues adding more constant driving force in the opening direction relative to.

  According to the present invention, an upstream main passage (2) for each cylinder connected to each cylinder, and a downstream main passage (3) formed by joining the upstream main passages (2) of a plurality of cylinders, Bypass passages (11, 14) branched from the upstream main passage (2) and the upstream main passage (2) so that the exhaust discharged from each cylinder flows to the bypass passages (11, 14). A flow path switching valve (4) that opens and closes and blocks communication between the upstream main passages (2) when closed; the flow path switching valve (4) is formed side by side with the housing (21). A plurality of valve bodies (24) that respectively open and close the plurality of valve openings (51) are attached to at least one common valve support (25), and the one valve support (25) ) Side of one rotating shaft supported rotatably ( 3) One arm portion (25B) to which the at least two valve bodies (24) are respectively assembled is integrally formed on one shaft portion (25A) that rotates integrally with 3), or the flow path switching valve In (4), a plurality of valve bodies (24A, 24B) for opening and closing a plurality of valve openings (51) formed side by side in the housing (21) are independent valve supports (25n, 25f) for each valve body. The valve support (25n, 25f) for each valve body is a shaft portion (25An, 25Af) that rotates integrally with a rotary shaft (23) that is rotatably supported on the housing (21) side. Further, an arm portion (25Bn, 25Bf) to which the at least two valve bodies (24A, 24B) are assembled is integrally formed. Each valve body (24) includes a valve body portion (26) and the valve body. Valve stem standing up from the section (26) 28), and the peripheral edge (26A) of the valve main body (26) abuts on and separates from the valve seat (52) at the upstream end of the valve opening (51), thereby allowing the valve opening (51 ) Is opened and closed, and the first arm portion (25B) or the arm portion (25Bn, 25Bf) for each valve body has a predetermined first gap in a direction perpendicular to the axis of the valve shaft portion (28). A through hole (27) into which the valve shaft part (28) is loosely fitted is formed, and the tip end of the valve shaft part (28) that protrudes through the through hole (27) to the opposite side of the valve body part (26). A retaining ring (29) having an outer diameter larger than that of the through hole (27) is provided between the one arm portion (25B) and the valve body (26) or an arm portion for each valve body ( 25Bn, 25Bf) and the valve body (26) are fixed with a predetermined second gap between them. At least two valve bodies (24 or 24A, 24B) assembled to the arm section (25B) of 1 or at least two valve bodies (24A, 24B) assembled to the arm sections (25Bn, 25Bf) for each of the valve bodies. In the engine exhaust system configured to open to the upstream side of the upstream main passage (2), at least two valve bodies (24) assembled to the one arm portion (25B) or each valve body At least two valve bodies (24A, 24B) assembled to the arm portions (25Bn, 25Bf) are aligned in the axial direction of the rotating shaft (23), and a driving force for rotating the rotating shaft (23) is rotated. A plurality of valve bodies (24) that act on only one end of the shaft (23) and are assembled to the one arm portion (25B) in the rotational direction of the rotating shaft (23). Or at least two valve bodies assembled to at least two valve bodies (24A, 24B) assembled to the arm sections (25Bn, 25Bf) for each valve body or to the arm sections (25Bn, 25Bf) for each valve body The first valve body (24A), which is a valve body closer to one end of the rotating shaft (23) on which the driving force acts, of the rotating shaft (23) on which the driving force acts on (24A, 24B). The arm portion (25B or 25Bn) to which the first valve body (24A) is assembled so as to be relatively closer to the valve opening (51) than the second valve body (24B) which is a valve body on the side far from one end. ) And the arm portion (25B or 25Bf) to which the second valve body (24B) is assembled, and when there is a valve opening request for the flow path switching valve (4), The rotation axis ( 3) is driven in the opening direction to bring the second valve element (24B) into contact with the stopper (55), so that the flow path switching valve (4) is fully opened, and the flow path switching valve (4 ) In the fully open state, a further constant driving force is continuously applied to the rotating shaft (23) in the valve opening direction, and when there is a request for closing the flow path switching valve (4) thereafter, the driving force Since the rotating shaft (23) is driven in the valve closing direction, the rotating shaft (23) is heated by the gas (exhaust) in the fully opened state even if a material having excellent creep resistance is adopted for the rotating shaft (23). Due to the torsional deformation, the difference between the angle of the arm part to which the first valve body (24A) is assembled and the angle of the arm part to which the second valve body (24B) is assembled is eliminated. The first valve body (24A) and the second valve body (2 4B) can be reliably seated on the corresponding valve seat portion.

According to the present invention, the exhaust passage of the engine is formed by joining the upstream main passage (2) for each cylinder connected to each cylinder of the engine and the upstream main passage (2) for each cylinder. The exhaust passage is composed of a downstream main passage (3) and a bypass passage (11, 14) branched from the upstream main passage (2). Exhaust gas discharged from each cylinder flows to the bypass passage (11, 14). As described above, a plurality of flow path switching valves (4) that open and close each of the upstream main passages (2) by a driving force of the drive device are provided, and the plurality of flow path switching valves (4) include at least two valves. In order to open and close the body (24A, 24B) by the driving device, the rotating shaft (23) orthogonal to the upstream main passage (2) and extending from the driving device and the rotating shaft (23) are provided. At least two valve supports (25n, 25f), and the at least two valve bodies (24A, 24B) have a predetermined interval in a direction perpendicular to the rotation axis (23) with respect to the at least two valve support bodies (25n, 25f). In the exhaust emission control device of the engine that is movably mounted, the valve support (25n) closer to the drive device among the at least two valve supports (25n, 25f) is more than the valve support (25f) far from the drive device. Also, an angular difference is provided so as to be relatively close to the seating position of the flow path switching valve in the upstream main passage (2), and when there is a request to open the flow path switching valve (4), The rotary shaft (23) is driven in the opening direction to bring the valve body (24B) far from the driving device into contact with the stopper (55), so that the flow path switching valve (4) is fully opened. Since the rotating shaft fully opened state of the road-switching valve (4) with respect to (23) continues adding more constant driving force in the opening direction, it adopts the material having excellent creep resistance to the rotation axis (23) However, the angle difference is eliminated by the torsional deformation of the rotating shaft (23) while being warmed by the gas (exhaust gas) in the fully open state, and thereby the at least two of the at least two first states are driven during the subsequent drive to the fully closed state. The valve body (24A, 24B) can be reliably seated on the corresponding valve seat portion.

  A first embodiment in which the present invention is applied as an exhaust system for an in-line four-cylinder engine will be described below with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing the piping layout of the exhaust device. First, the configuration of the entire exhaust device will be described based on FIG. For each cylinder 1 consisting of a first cylinder (# 1 cylinder), a second cylinder (# 2 cylinder), a third cylinder (# 3 cylinder), and a fourth cylinder (# 4 cylinder) arranged in series, Is connected to the upstream main passage 2. The four upstream main passages 2 individually connected to the four cylinders merge as one downstream main passage 3 at the downstream side, and in other words, the upstream main passage 2 A flow path switching valve 4 that opens and closes the four upstream main passages 2 at the same time is provided at a portion that becomes a boundary with the downstream main passage 3. The switching valve 4 is closed when it is cold, and when closed, the upper and lower communication between the upstream main passage 2 and the downstream main passage 3 is blocked and the four upstream main passages 2 are closed. It is the structure which is made into a mutually non-communication state between.

  A main catalyst 8 is interposed in the middle of the downstream main passage 3 extending downstream from the flow path switching valve 4. The main catalyst 8 has a large capacity arranged under the floor of the vehicle, and includes a three-way catalyst and an HC trap catalyst as the catalyst. The upstream main passage 2, the downstream main passage 3, and the main catalyst 8 constitute a main flow path through which exhaust flows during normal operation.

  On the other hand, an upstream bypass passage 11 is branched from each of the upstream main passages 2 as bypass passages. The upstream bypass passage 11 has a sufficiently smaller passage cross-sectional area than the upstream main passage 2, and the branch point 12 serving as the upstream end of the upstream bypass passage 11 is set at a position as upstream as possible in the upstream main passage 2. Has been. The four upstream bypass passages 11 merge as one downstream bypass passage 14 at the downstream junction 13.

  In FIG. 1 schematically showing each passage, each upstream bypass passage 11 is drawn relatively long, but in practice it is as short as possible. In other words, the downstream bypass passage 14 joins with the shortest distance.

  The downstream end of the downstream bypass passage 14 joins the downstream main passage 3 at a junction 17 upstream of the main catalyst 8 in the downstream main passage 3. A bypass catalyst 18 using a three-way catalyst is interposed in the downstream bypass passage 14. The bypass catalyst 18 is disposed as upstream as possible in the bypass flow path. The bypass catalyst 18 is a small one having a smaller capacity than the main catalyst 8, and a catalyst excellent in low temperature activity is preferably used.

  One end of the exhaust gas recirculation passage 15 is connected to the downstream main passage 3 upstream of the junction 17 to the downstream main passage 3 of the downstream bypass passage 14. The other end of the exhaust gas recirculation passage 15 extends to the intake system of the engine via an exhaust gas recirculation control valve (not shown).

  In the engine exhaust system configured as described above, when the engine temperature after the cold start or the exhaust temperature is low when the flow path switching valve 4 is required to be closed, the flow is switched via an appropriate motor (actuator). The path switching valve 4 is closed and the main flow path is shut off. Therefore, the entire amount of exhaust discharged from each cylinder 1 flows from the branch point 12 to the bypass catalyst 18 through the upstream bypass passage 11 and the downstream bypass passage 14. Since the bypass catalyst 18 is located upstream of the exhaust system, that is, close to the cylinder 1 and is small in size, the bypass catalyst 18 is activated quickly and exhaust purification is started at an early stage. At this time, the flow path switching valve 4 is closed, so that the upstream main passages 2 of the cylinders 1 are not in communication with each other. Therefore, a phenomenon in which the exhaust discharged from a certain cylinder wraps around the upstream main passage 2 of the other cylinder is prevented, and a decrease in the exhaust gas temperature due to this wraparound is surely avoided.

  On the other hand, when there is a request to open the flow path switching valve 4, that is, when the warm-up of the main catalyst 8 proceeds and becomes activated, the flow path switching valve 4 is opened. As a result, the exhaust discharged from each cylinder 1 passes through the main catalyst 8 mainly through the upstream main passage 2 and the downstream main passage 3. At this time, the bypass flow path side is not particularly shut off, but the bypass flow path side has a smaller passage cross-sectional area than the main flow path side and the bypass catalyst 18 is interposed. Most of the flow passes through the main flow path side and hardly flows into the bypass flow path side. Therefore, the thermal deterioration of the bypass catalyst 18 is sufficiently suppressed. In addition, since the bypass flow path side is not completely shut off, at high rotation speed and high load where the exhaust flow rate becomes large, a part of the exhaust flow flows through the bypass flow path side, thereby avoiding a reduction in charging efficiency due to back pressure. it can.

  Next, the configuration of the flow path switching valve 4 will be described. However, since the basic configuration itself of the flow path switching valve 4 is publicly known (see Japanese Patent Application Laid-Open No. 2008-8284), the basic configuration of the flow path switching valve 4 is based on FIGS. I will outline it first. 2 is a partially sectional plan view of the flow path switching valve 4, FIG. 3 is a partially longitudinal sectional view of the housing 21 in a fully closed state, and FIG. 4 is a housing 21, a valve support 25, and a cover 40. FIG.

  The flow switching valve 4 for four cylinders is integrated as a single valve unit, and four cylindrical valve openings 51 are provided in a housing 21 having a substantially rectangular shape along a surface orthogonal to the flow. Openings are formed in two rows, that is, at positions that are the vertices of a square. That is, as shown in FIG. 3, four cylindrical valve openings 51 perpendicular to the housing upper surface 21 </ b> A are formed in the housing 21, and a valve main body 26 described later is formed at the upstream end of the valve opening 51. A taper-shaped valve seat portion 52 on which is seated is formed. The valve opening 51 is a part of the downstream main passage 2.

  A pair of rotating shafts 23 are arranged in parallel to each other on both sides of the housing 21. A pair of disk-shaped valve bodies 24 that open and close a pair of adjacent valve openings 51 are attached to the rotary shaft 23 via a common valve support 25.

  The valve support 25 includes a shaft portion 25A provided on the outer periphery of the rotating shaft 23, and a pair of arm portions projecting radially outward from the outer periphery of both ends of the shaft portion 25A in the axial direction, and the pair of valve bodies 24 being assembled respectively. 25B. In particular, the shaft portion 25A of the valve support 25 and the rotary shaft 23 are integrally formed. That is, the shaft portion 25A and the arm portion 25B of the valve support 25 including the rotary shaft 23 are integrally formed. ing. The arm portion 25B has a substantially rectangular plate shape, the base end portion is integrally connected to the shaft portion 25A, and as shown in FIG. 3, the distal end portion has a through-hole (mounting hole) 27 having a circular cross section. have.

  The valve body 24 includes a disc-shaped valve main body portion 26 and a valve shaft portion 28 that stands vertically from the central portion of the valve main body portion 26. The disc-shaped valve main body portion 26 has a peripheral edge 26A. And a lower surface 26B, which is a flat surface, and an upper surface 26C, which is also a flat surface. Then, the valve opening 51 is opened and closed by the peripheral edge 26 </ b> A of the valve main body 26 coming into contact with and separating from the valve seat portion 52 at the upstream end of the valve opening.

  The valve shaft portion 28 passes through the through-hole 27 through a predetermined gap (this gap is referred to as “first gap”) in a direction perpendicular to the axial direction of the valve shaft portion 28 with respect to the arm portion 25B (in FIGS. 3 and 7). It is configured to be loosely fitted in the left and right direction, that is, loosely fitted. Then, a so-called washer having a larger outer diameter than the through hole 27 is formed at the tip end of the valve shaft portion 28 that passes through the through hole 27 and protrudes to the opposite side (upper side in FIG. 3) of the valve main body portion 26. A disc-shaped retaining ring 29 is fixed. The retaining ring 29 prevents the valve body 24 from coming off from the valve support body 25. Further, as shown in FIG. 7, a base portion 28A having a diameter larger than that of the through hole 27 is provided at the base portion of the valve shaft portion 28. Between the upper surface 28B of the base portion 28A and the lower surface 25C of the arm portion 25B. The holding ring 29 is positioned in the axial direction of the valve shaft portion 28 so that a predetermined gap in the axial direction of the valve shaft portion 27 is formed in the axial direction of the valve shaft portion 27, thereby the arm portion 25B. On the other hand, the valve shaft portion 28 is loosely fitted also in the axial direction of the valve shaft portion 28 (circumferential direction around the rotation shaft 23). The base 18A may not be provided.

  Here, if the first clearance and the second clearance are collectively referred to as “clearance”, the valve body 24 is configured to be the valve shaft portion with respect to the arm portion 25B by the clearance between the valve body 24 and the arm portion 25B. 28 and the direction orthogonal to the axial direction of the valve shaft portion 28 (circumferential direction around the rotation shaft 23) are not completely fixed, and the peripheral edge 26A of the valve body portion 26 is A slight swing (so-called swinging) is possible with respect to the arm portion 25B so that the valve seat portion 52 at the upstream end of the opening 51 can be satisfactorily intimately contacted.

  From the viewpoint of ensuring sealing performance due to the pressure difference, the valve body 24 opens and closes the valve opening 51 from the upstream side, that is, as shown in FIGS. 3 and 7, the upstream side (cylinder) of the main upstream side passage 2. 1 combustion chamber side). In this case, the end (not shown) of the exhaust pipe of each cylinder that becomes the upstream main passage 2 is configured to have a substantially U-shaped cross section so as to accommodate the oscillating valve body 24, and each valve opening. Each of them is welded along the partition wall 30 of the housing 21 that surrounds 51. Therefore, the upstream main passage 2 of each cylinder is completely separated and independent on the upstream side of the housing 21.

  Each rotary shaft 23 is sandwiched between the cover 40 and the housing 21 and is rotatably supported on the housing 21 side by three bearing portions 31, 32, 33. Each cover 40 is fastened and fixed to the housing 21 at the positions of the bearing portions 31, 32, 33 by a plurality of fixing bolts 41 (see FIG. 4) with the rotating shaft 23 sandwiched therebetween. The cover 40 is formed with a plurality of bolt through holes 42 through which the fixing bolts 41 are inserted, and the housing 21 is formed with a bolt hole 43 in which a female screw into which the fixing bolt 41 is screwed is formed.

  A link plate 34 is attached to one end of the rotating shaft 23 protruding from the housing 21, and the rotating shaft 23 is driven in the rotational direction via the link plate 34. Here, the link plates 34 of the two rotating shafts 23 are interlocked with each other via an interlocking mechanism (not shown) such as an appropriate link mechanism, and are simultaneously opened and closed symmetrically by a single motor (actuator) not shown. Operate. That is, the four valve bodies 24 open and close all at once.

  Cylindrical seal bushes 44 and 45 are attached in advance to the two journal portions 23A of the rotary shaft 23 that are rotatably held between the housing 21 and the cover 40 by the bearing portions 31 and 33 on both sides. Yes. Further, a substantially annular spacer 46 is attached to the shaft portion 25A of the valve support 25 in the bearing portion 32 between the two adjacent arm portions 25B so as to fill a gap between the housing 21 and the cover 40 side. ing. As shown in FIG. 5, the spacer 46 is formed with an opening 46 </ b> A that fits into the connecting piece 25 </ b> C protruding from the outer periphery of the shaft 25 </ b> A so as to connect the two arms 25 </ b> B of the valve support 25. It is almost C-shaped.

  The mounting angle of each valve body 24 with respect to the rotating shaft 23, more specifically, the angle of the two arm portions 25B with respect to the shaft portion 25A of the valve support 25 is, for example, as follows. This will be described with reference to the reference examples shown in FIGS. 6 and 8. The angles of the two arm portions 25B with respect to the shaft portion 25A of the valve support 25 are different from each other as shown in FIGS. That is, with respect to the rotational direction of the rotating shaft 23, the link plate 34 is more than the valve body 24A (see FIG. 8) closer to the link plate 34 that is the driven point (this valve body is hereinafter referred to as “first valve body”). The first valve body 24A is assembled so that the valve body on the side far from the valve body (this valve body is hereinafter referred to as "second valve body") 24B (see FIG. 8) is relatively closer to the valve opening 51. A slight angle difference θ is provided between the arm portion 25B and the arm portion 25B to which the second valve body 24B is assembled, that is, between both arm portions 25B. Therefore, when the rotary shaft 23 is driven in the closing direction, the second valve body 24B is seated on the valve seat portion 52 corresponding to the first, and then the first valve body 24A is accompanied by the twisting deformation of the rotary shaft 23. Is seated on the corresponding valve seat portion 52. Therefore, the seal surface pressure of the second valve body 24B is increased, and a seal surface pressure substantially equal to that of the first valve body 24A is obtained. FIG. 8 shows the state of the first and second valve bodies 24A and 24B in the valve open state (fully open state).

  In order to ensure such a good sealing performance, high dimensional accuracy is required for the mounting angle of both valve bodies 24A and 24B, that is, the angle (angle difference θ) of the two arm portions 25B. However, if the two arm parts are separated and each is assembled separately to the rotating shaft 23, the angle of the arm part is highly accurate due to errors and dimension crossings during manufacture and assembly. It is difficult to ensure, and it is difficult to ensure good sealing performance.

  On the other hand, in the present embodiment, one valve support 25 is connected to one shaft portion 25A that rotates integrally with one rotation shaft 23 that is rotatably supported on the housing 21 side. It is assumed that one arm portion 25B to which each is assembled is integrally formed. For this reason, in addition to the simplification and downsizing of the structure and the simplification of the assembly work by reducing the number of parts, as compared with the case where a plurality of arm parts are individually attached to the rotating shaft as described above, It is possible to reduce assembling variation of a plurality of valve bodies due to errors during production and assembly, and to significantly improve the assembling dimensional accuracy of the valve body 24. As a result, the sealing performance and its reliability are remarkably improved. Can do.

  In addition, a cover 40 that rotatably holds the rotating shaft 23 together with the housing 21 is fixed to the housing 21 by a plurality of fixing bolts 41 with the rotating shaft 23 interposed therebetween. Compared to the above, the assembly work is simplified.

  Further, since the bushes 44 and 45 are attached in advance to the journal portion 23A of the rotating shaft 23 that is rotatably held by the bearing portions 31 and 33 of the housing 21 and the cover 40, the assembly work is simplified. These bushes 44 and 45 can reliably prevent gas leakage to the outside, and can further improve the sealing performance.

  In addition, the shaft portion 25A of the valve support 25 has a gap between the two adjacent arm portions 25B and rotatably supported by the bearing portion 32 between the housing 21 and the cover 40 side. A spacer 46 is attached so as to be buried. Accordingly, while the valve support 25 is formed in an integrated shape, the gap generated in this portion by the spacer 46 can be suppressed to the minimum, and the temperature rise performance and the seal reliability can be improved.

  Furthermore, in this embodiment, since the rotating shaft 23 and the shaft portion 25A of the valve support 25 are integrally formed, it is possible to further reduce the number of parts and improve the dimensional accuracy.

  This completes the outline of the basic configuration of the flow path switching valve 4 of the reference example.

  Now, as described above, the pair of link plates 34 are interlocked with each other via an interlocking mechanism (not shown) such as an appropriate link mechanism, and the four valve bodies 24 are simultaneously connected by a single motor (actuator or driving device) (not shown). Open and close symmetrically. Specifically, as described in the reference examples shown in FIGS. 6 and 8, the second valve body 24B (see FIG. 8) is more in the first valve body 24A (see FIG. 8) with respect to the rotation direction of the rotating shaft 23. A slight angle difference θ is provided between the arm portions 25B so as to be relatively closer to the valve opening 51. Therefore, when the rotary shaft 23 is driven in the closing direction, the second valve body 24B is seated on the valve seat portion 52 corresponding to the first, and then the first valve body 24A is accompanied by the twisting deformation of the rotary shaft 23. Is seated on the corresponding valve seat portion 52.

  This will be further described with reference to FIGS. Here, in the reference example described above, one valve support 25 is connected to one shaft 25A that rotates integrally with one rotation shaft 23 that is rotatably supported on the housing 21 side, and two valve bodies 24A. Unlike the reference example, in FIG. 9 and FIG. 10, the valve support 25 is separately provided for each of the valve bodies 24A and 24B. It is formed by the body. Hereinafter, the valve support body on the first valve body 24A side is “25n”, the valve support body on the second valve body 24B side is “25f”, and the shaft portion and the arm constituting the valve support body 25n on the first valve body 24A side The parts are designated as “25An” and “25Bn”, respectively, and the shaft part and the arm part constituting the valve support 25f on the second valve body 24B side are distinguished as “25Af” and “25Bf”, respectively. However, the valve support is separately provided for each valve body for the sake of consideration. Similarly to the above-described reference example, one valve support 25 is rotatably supported on the housing 21 side. It does not matter if one arm portion 25B to which the two valve bodies 24A and 24B are respectively assembled is integrally formed with one shaft portion 25A that rotates integrally with the rotary shaft 23.

  Now, let us say that a set of parts in which one rotating shaft 23, two valve bodies 24A and 25B, and valve support bodies 25n and 25f for each valve body are integrated is called a "valve assembly". FIG. 10 is an elevation view of the valve assembly. However, FIG. 10 shows three patterns (pattern 1, pattern 2, pattern 3) in which the angles of the two arm portions 25Bn and 25Bf for each valve element are different.

  In FIG. 10, the position near the link plate 34 serving as the driven point in the rotating shaft 23 is the first position a, the position far from the link plate 34 serving as the driven point is the third position c, and the first position a. And the center position of the 3rd position c is made into the 2nd position b. The reason why the three positions a, b, and c are determined in the axial direction of the rotating shaft 23 in this way is to identify a portion where torsional deformation occurs.

  In the above reference example, the rotary shaft 23 and the two valve bodies 24A and 24B are in the initial position shown by the pattern 2 in FIG. 10, and the second valve body 24B is seated on the corresponding valve seat portion 52 when fully closed. Thereafter, by further applying a driving force to the rotating shaft 23 in the valve closing direction by the motor, the portion from the left end (one end) of the rotating shaft 23 on which the motor driving force acts to the second position b is twisted, and the first valve The body 24A is seated on the corresponding valve seat portion 52, so that the rotation shaft 23 is in a state where the angle difference between the arm portions 25Bn and 25Bf is zero, that is, the state of the pattern 1 in FIG. . This is based on the following concept. That is, in order to satisfy the sealing performance of the flow path switching valve 4, it is desired to eliminate the angle difference (phase difference) between the arm portions 25Bn and 25Bf. Therefore, the initial state of the rotary shaft 23 and the two valve bodies 24A and 24B is ideally the pattern 1 in FIG. 10 having no angle difference between the arm portions 25Bn and 25Bf. Within the range, the angle difference between the two arm portions 25Bn and 25Bf varies. Accordingly, the initial state of the rotary shaft 23 and the two valve bodies 24A and 24B is set in advance as pattern 2 in FIG. 10, and the rotary shaft 23 is driven in the closing direction in this initial state, and the valve seat portion 52 corresponding to the second valve body 24B. After being seated on the armature, as a second stage, the rotational shaft 23 is twisted and deformed to absorb the variation caused in the angle difference between the arm portions 25Bn and 25Bf.

  Here, reconsidering again, when fully closed, a constant amount of motor driving force is continuously applied to the rotating shaft 23 in the closing direction, so that the second end from the left end (one end) of the rotating shaft 23 on which the motor driving force acts is applied. If twisting deformation is caused to the position b and the rotating shaft 24 is driven in the opening direction to be in the fully opened state, the portion from the left end of the rotating shaft 23 to the second position b is in an initial state before twisting deformation. Return to. Such torsional deformation and the return to the initial state before the torsional deformation utilize the creep characteristics of the material constituting the rotating shaft 23, but the torsional deformation and the return to the initial state before the torsional deformation are performed. If the number of times (frequency) is increased, a problem may occur. That is, if the engine is used over a long period of time, it is repeatedly applied to the portion from the left end of the rotating shaft 23 on which the motor driving force acts to the second position b, torsional deformation, and return to the initial state before the torsional deformation. As a result, fatigue may occur in the material of the portion from the left end of the rotating shaft 23 to the second position b, and the portion may be broken.

  In particular, not only when the engine is cold-started (operating conditions where the flow-path switching valve is required to close), but also when the main catalyst 8 becomes inactive again after the cold start (similarly, the flow-path-switching valve is closed). In the operating condition where the valve is required), the rotation shaft 24 is driven in the closing direction to switch the flow path switching valve 4 from the fully open state to the fully closed state. Since the number of occurrences of the return of the increase further increases, the possibility of breakage is considered to increase.

  In order to prevent such a breakage of the rotating shaft 23, that is, to ensure long-term reliability of the rotating shaft 23, the material of the rotating shaft 23 is made of a material excellent in creep resistance (a property that is difficult to creep). It is to be.

  However, excellent creep resistance means that the material is difficult to twist and deform. Therefore, when the rotary shaft 23 is made of a material excellent in creep resistance, the second position b from the left end of the rotary shaft 23 when fully closed. As a result of the amount of torsional deformation in the portion up to that being less than the amount of torsional deformation of the material used in the above reference example, the first valve body 24A is seated only incompletely and the sealing performance is insufficient. It is conceivable that

  Therefore, the first embodiment of the present invention changes the concept, and the initial state of the rotary shaft 23 and the two valve bodies 24A and 24B is shown in the pattern 3 of FIG. A slight angle difference θ is provided between the arm portions 25Bn and 25Bf so that the single valve body 24A is relatively closer to the valve opening 51 than the second valve body 24B. This is because the operation time in the market is overwhelmingly longer when the flow path switching valve 4 is in the fully open state than when it is in the fully closed state, and when the temperature at the time of torsional deformation occurring in the rotating shaft 23 is fully open. It pays attention to the fact that there is a big difference between when fully closed and when fully closed.

  More specifically, when the rotating shaft 23 is driven in the opening direction (when there is a request to open the flow path switching valve 4), the rotating shaft 23 is driven in the opening direction by the motor driving force, and the second valve As shown in FIG. 11, the body 24B is first brought into contact with the stopper 55 for determining the fully open position, whereby the flow path switching valve 4 is fully opened, and in this fully open state, the valve opening direction is set with respect to the rotary shaft 23. Further, a constant motor driving force is continuously applied. In this case, the flow path switching valve 4 is fully opened after the warm-up of the main catalyst 8 is completed, and therefore the gas (exhaust gas) is at a high temperature. In this high temperature atmosphere, the amount of torsional deformation of the portion from the left end of the rotating shaft 23 on which the motor driving force acts to the second position b is an effect of the motor driving force immediately after the engine is cold started (low temperature state). Since the amount of twist deformation of the portion from the left end of the rotating shaft 23 to the second position b is larger by the temperature difference, the material excellent in the creep resistance than the material used in the above reference example for the rotating shaft 23 However, if a constant motor driving force is continuously applied to the rotating shaft 23 in the valve opening direction when fully opened, the portion from the left end of the rotating shaft 23 on which the motor driving force acts to the second position b is removed. Unlike the state immediately after the cold start of the engine (low temperature state), it becomes possible to torsionally deform as required, and the rotary shaft 23 and the two valve bodies 24A, 24B are placed between both arm portions 25Bn, 25Bf. Zero angle difference That may be the state of the pattern 1 in FIG. 10. In FIG. 11, the cover 40 in the reference example shown in FIG. 4 is not shown, but the cover 40 can also be provided in this embodiment as in the reference example.

  When the main catalyst 8 is deactivated again due to a change in operating conditions after the activation of the main catalyst 8, the rotating shaft 23 is driven in the closing direction and the flow path switching valve 4 is changed from the fully open state to the fully closed state. Switched to At this time, since the rotary shaft 23 and the two valve bodies 24A, 24B are in the state of the pattern 1 in FIG. 10, the two valve bodies 24A, 24B are seated on the corresponding valve seat portions 52 almost simultaneously. As described above, in this embodiment, the portion from the left end of the rotating shaft 23 on which the motor driving force acts to the second position b is twisted and deformed when the gas is at a high temperature after activation of the main catalyst 8. 10 is generated and brought into the state of pattern 1 in FIG. 10, from the left end of the rotating shaft 23 on which the motor driving force acts to the second position b when the main catalyst 8 is not fully activated immediately after the cold start. Thus, no torsional deformation is caused in this part.

  On the other hand, in the above reference example, when the rotary shaft 23 is driven in the opening direction and the flow path switching valve 4 is fully opened, the torsional deformation is removed from the rotary shaft 23 and the initial pattern 2 shown in FIG. In this initial state, even if the motor driving force is further applied in the valve opening direction to the rotating shaft 23 as in the present embodiment, the second position b to the third position c are continued. Since the portion is in a free state, only the portion from the left end of the rotating shaft 23 on which the motor driving force acts to the first position a is twisted, and the angle difference between the arm portions 25Bn and 25Bf is eliminated. It will never be done.

  On the other hand, in this embodiment, when the rotary shaft 23 and the two valve bodies 24A, 24B adopting a material excellent in creep resistance are in the initial state shown in the pattern 3 of FIG. The torsional deformation of the portion from the left end of the rotating shaft 23 on which the force acts to the second position b is insufficient, and the second valve body 24B is seated incompletely on the corresponding valve seat portion 52. In other words, the angle difference (phase difference) between the two arm portions 25Bn and 25Bf is resolved after the end of the torsional deformation of the rotating shaft 23 when fully opened, but both arm portions are fully closed immediately after the engine cold start. The sealing performance of the valve body 24B on the side far from the link plate 34 serving as a non-driving point is insufficient due to the angle difference between 25Bn and 25Bf.

  Further, even if the rotary shaft 23 and the two valve bodies 24A and 24B are in the state of the pattern 1 in FIG. 10 and the two valve bodies 24A and 24B are seated on the corresponding valve seat portion 52, if time passes. It is conceivable that the rotating shaft 23 returns to the initial state before the torsional deformation (pattern 3 in FIG. 10), and after returning to the initial state, the angle difference (phase difference) between the arm portions 25Bn and 25Bf. As a result, the sealing performance of the valve body 24B on the side far from the link plate 34, which is a non-driving point, becomes insufficient.

  In order to cope with this, in the present embodiment, the above-described clearance for the valve body 24 (clearance between the valve body 24 and the arm portion 25B) is used to connect the two valve bodies 24A and 24B together. 52 is surely seated. At that time, further, the clearance between the first valve body 24A and the arm portion 25Bn to which the first valve body is assembled is determined between the second valve body 24B and the arm portion 25Bf to which the second valve body is assembled. Less than the clearance.

  Here, the reason why the clearance between the valve body and the arm portion is smaller in the first valve body 24A than in the second valve body 24B is as follows. That is, in consideration of the angle difference between the arm portions 25Bn and 25Bf in the initial state shown in the pattern 3 of FIG. 10 in the first embodiment, the valve seat portions 52 corresponding to the two valve bodies 24A and 24B. The sealing performance of the flow path switching valve 4 can also be ensured by equally providing clearance that can be seated on the flow path.

  However, until the angular difference between the arm portions 25Bn and 25Bf is eliminated by the torsional deformation of the rotary shaft 23 in the fully opened state, only the second valve body 24B is held by the stopper 55 when fully opened. Since the valve body 24A is not held, the first valve body 24A flickers (oscillates / vibrates), and the durability of the first valve body 24A becomes a problem. This is because the first valve body 24A hits a corresponding stopper (not shown) until the angular difference (phase difference) between the arm portions 25Bn and 25Bf is eliminated by the torsional deformation of the rotating shaft 23 in the fully opened state. Since the first valve body 24A is exposed to high-temperature and high-pressure exhaust in a free state in which a gap is provided between the stopper and the stopper, the first valve body 24A is not exposed to the arm portion 25Bn. Because it swings and vibrates).

  In this case, if the clearance that can be seated on the corresponding valve seat portion 52 is given to the two valve bodies 24A and 24B equally, the clearance between the first valve body 24A and the arm portion 25Bn is large. The flutter generated in the body 24 also increases.

  Therefore, in order not to give more than necessary clearance for the first valve body 24A, the clearance between the first valve body 24A and the arm portion 25Bn is smaller than the clearance between the second valve body 24B and the arm portion 25Bf. To do. That is, the clearance of the first valve body 24A is made smaller than that of the second valve body 24B, thereby preventing the first valve body 24A from fluttering (swinging / vibrating) as much as possible and the durability of the first valve body 24A. I tried to improve the performance.

  In this way, in the present embodiment, there is an angle difference between the arm portions 25Bn and 25Bf at the time of cold start of the engine, or the rotating shaft 23 is in the state of pattern 1 in FIG. The two valve bodies 24A, 24B return to the initial state (pattern 3 in FIG. 10) before the rotary shaft 23 is twisted and deformed after a lapse of time after sitting on the corresponding valve seat portions 52, and both arm portions 25Bn, 25Bf. 10 can be absorbed by the clearance between the valve bodies 24A and 24B and the arm portions 25Bn and 25Bf for each valve body, as shown in pattern 3 in FIG. Even in the initial state or when the initial state shown in the pattern 3 of FIG. 10 is restored, the two valve bodies 24A and 24B can be seated together on the corresponding valve seat portions 52. Both in subsequent open state can be first valve body 24A as much as possible to prevent flapping.

  Thus, according to the present embodiment (the invention according to claim 2), the upstream main passage 2 for each cylinder connected to each cylinder and the upstream main passages 2 of a plurality of cylinders merge. The downstream main passage 3, the bypass passages 11 and 14 branching from the upstream main passage 2, and the upstream main passage 2 is opened and closed so that the exhaust discharged from each cylinder flows to the bypass passages 11 and 14. A flow path switching valve 4 that shuts off communication between the upstream main passages 2 when closed, and the flow path switching valve 4 opens and closes a plurality of valve openings 51 formed side by side in the housing 21. Four (a plurality of) valve bodies are attached to independent valve supports 25n and 25f for each valve body, and the valve support bodies 25n and 25f for each valve body are rotatably supported on the housing 21 side. Rotate with 23 Arm portions 25Bn and 25Bf to which two (at least two) valve bodies 24A and 24B are respectively assembled are formed integrally with the shaft portions 25An and 25Af. Each valve body 24 includes a valve body portion 26 and the valve body. A valve shaft portion 28 rising from the portion 26, and the valve opening 51 is opened and closed by the peripheral edge 26 </ b> A of the valve main body portion 26 coming in contact with and separating from the valve seat portion 52 at the upstream end of the valve opening 51, A through hole 27 in which the valve shaft portion 28 is loosely fitted is formed in the arm portions 25Bn and 25Bf for each valve body by having a predetermined first gap in a direction orthogonal to the axis of the valve shaft portion 28. A holding ring 29 having an outer diameter larger than that of the through hole 27 is provided at the distal end portion of the valve shaft portion 28 that penetrates the outer side of the valve body portion 26 and penetrates the valve body portion 26. Leaving a predetermined second gap between In the engine exhaust system, two (at least two) valve bodies 24A, 24B assembled to the arm portions (25Bn, 25Bf) for each valve body are configured to open upstream of the upstream main passage 2. The two valve bodies 24A and 24B assembled to the arm portions 25Bn and 25Bf for each valve body are aligned in the axial direction of the rotary shaft 23, and a driving force for rotating the rotary shaft 23 is used as the rotary shaft 23. Of the rotary shaft 23 on which the driving force acts, out of two (at least two) valve bodies 24A and 24B assembled to the arm portions 25Bn and 25Bf for each valve body in the rotation direction of the rotary shaft 23. The first valve body 24A which is a valve body closer to one end is relatively closer to the valve opening 51 than the second valve body 24B which is a valve body farther from one end of the rotating shaft 23 on which the driving force acts. Near Therefore, when there is an angle difference between the arm portion 25Bn to which the first valve body 24A is assembled and the arm portion 25Bf to which the second valve body 24B is assembled, and there is a request to open the flow path switching valve 4, By driving the rotary shaft 23 in the opening direction by the driving force and bringing the second valve body 24B into contact with the stopper 55, the flow path switching valve 4 is fully opened, and the flow path switching valve 4 is rotated in the fully opened state. When a constant driving force is further applied to the shaft 23 in the valve opening direction, and the valve switching valve 4 is subsequently requested to close, the rotating shaft 23 is driven in the valve closing direction by the driving force. Even if a material excellent in creep resistance is adopted for the shaft 23, the angle of the arm portion 25Bn to which the first valve body 24A is assembled by the torsional deformation of the rotating shaft 23 while being heated by the gas (exhaust) in the fully opened state, Second valve body 24 This eliminates the difference from the angle of the arm portion 25Bf to which the first and second valve bodies 24B and 24B are seated on the corresponding valve seat portions when driving to the fully closed state. be able to.

  According to the present embodiment (the invention described in claim 3), since the material of the rotating shaft 23 is a material excellent in creep resistance, the twisting deformation acting on the rotating shaft 23 and the initial state before the twisting deformation are achieved. Even if the return of the rotation repeatedly occurs, the durability of the rotating shaft 23 can be enhanced.

  According to this embodiment (the invention described in claim 7), the first valve body 24A is smaller in the first gap and the second gap than the second valve body 24B. Immediately after 4 is changed from the fully closed state to the fully opened state, the first valve body 24A is heated to a high temperature in a free state in which a gap is provided between the first valve body 24A and the stopper with which the first valve body 24A abuts. Even when exposed to high-pressure exhaust, flutter (swing / vibration) generated in the first valve body 24A can be suppressed, and the durability of the first valve body 24 can be improved.

  Further, according to the present embodiment (the invention described in claim 8), the exhaust passage of the engine has an upstream main passage 2 for each cylinder connected to each cylinder of the engine, and an upstream side for each cylinder. The main passage 2 is composed of a downstream main passage 3 and a bypass passage (11, 14) branched from the upstream main passage 2. Exhaust gas discharged from each cylinder is bypassed (11, 14). Are provided with a plurality of flow path switching valves 4 in which the respective upstream main passages 2 are opened and closed by the driving force of the driving device. The plurality of flow path switching valves 4 include at least two valve bodies 24A and 24B. In order to open and close by the driving device, the rotating shaft 23 is orthogonal to the upstream main passage 2 and extends from the driving device, and at least two valve supports 25n and 25f provided on the rotating shaft 23, and the number is small. In the engine exhaust purification apparatus, the two valve bodies 24A and 24B are attached to the at least two valve support bodies 25n and 25f so as to be movable at a predetermined interval in a direction perpendicular to the rotation shaft 23 (vertical direction in FIG. 9). Of the at least two valve supports 25n and 25f, the valve support 25n closer to the drive device is more relative to the seating position of the flow path switching valve 4 in the upstream main passage 2 than the valve support 25f far from the drive device. Therefore, even if a material having excellent creep resistance is adopted for the rotating shaft 23, the rotating shaft 23 is twisted and deformed while being heated by gas (exhaust) in a fully opened state. The above-mentioned angular difference is eliminated, so that at least the two valve bodies 24A and 24B are securely seated on the corresponding valve seats when driven to the fully closed state. It can be.

  As described above, the present invention has been described based on specific embodiments. However, the present invention is not limited to the above embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, the invention is not limited to a four-cylinder engine as in the above embodiment, or a configuration in which two valve bodies 24 share one rotating shaft 23, but a configuration in which three or more valve bodies share a rotating shaft. The present invention is also applicable. Further, in the above-described valve shaft portion 28, the portion where the retaining ring 29 is press-fitted and fixed is made smaller than the portion where the through hole 27 of the arm portion 25B is loosely fitted. Is optional. The engine may be either a gasoline engine or a diesel engine.

  In the embodiment, the first valve body 24A has been described as having the first gap and the second gap smaller than the second valve body 24B, but the first valve body 24A is the second valve body. The first gap or the second gap may be made smaller than 24B (the invention according to claim 5).

The schematic diagram of the piping layout of an exhaust apparatus. The partial cross section top view of the flow-path switching valve of a reference example. The partial longitudinal cross-sectional view of a housing when the flow-path switching valve of a reference example is in a fully closed state. The perspective view which shows the housing of the reference example, a valve support body, and a cover. Explanatory drawing which shows the spacer assembled | attached to the axial part of the valve support body of a reference example. Explanatory drawing at the time of providing an angle difference in the two arm parts of a reference example. The partial longitudinal cross-sectional view of the housing at the time of valve opening drive of the flow-path switching valve of a reference example. Explanatory drawing which shows the mode of two valve bodies in the valve opening state of the flow-path switching valve of a reference example. The top view of the valve assembly of 1st Embodiment. The elevational view in the initial state of the valve assembly shown about three patterns. Explanatory drawing which shows the mode of the 2nd valve body in the valve opening state of the flow-path switching valve of 1st Embodiment.

Explanation of symbols

2 ... Upstream side main passage 3 ... Downstream side main passage 4 ... Flow path switching valve 8 ... Main catalyst 11, 14 ... Bypass passage 18 ... Bypass catalyst 21 ... Housing 23 ... Rotary shaft 24 ... Valve body 24A ... First valve body 24B ... 2nd valve body 25 ... Valve support body 25A ... Shaft part 25B ... Arm part 25Bn ... Arm part to which the first valve body is assembled 25Bf ... Arm part to which the second valve body is assembled 26 ... Valve body part 26A ... Peripheral 28 ... Valve shaft part 51 ... Valve opening part 52 Valve seat part 55 ... Stopper

Claims (8)

An upstream main passage for each cylinder connected to each cylinder;
A downstream main passage formed by joining upstream main passages of a plurality of cylinders;
A bypass passage branched from the upstream main passage,
A flow path switching valve that opens and closes the upstream main passage so that the exhaust discharged from each cylinder flows to the bypass passage, and shuts off the communication between the upstream main passages when closed.
In the flow path switching valve, a plurality of valve bodies that respectively open and close a plurality of valve openings formed side by side in the housing are attached to at least one common valve support body. A single arm portion, to which the at least two valve bodies are assembled, is integrally formed on a single shaft portion that rotates integrally with a single rotation shaft that is rotatably supported by
Each of the valve bodies has a valve main body portion and a valve shaft portion standing up from the valve main body portion,
The valve opening is opened and closed by the peripheral edge of the valve main body contacting and leaving the valve seat at the upstream end of the valve opening,
A through hole in which the valve shaft portion is loosely fitted is formed in the one arm portion by having a predetermined first gap in a direction orthogonal to the axis of the valve shaft portion, and the valve body passes through the through hole. A holding ring having an outer diameter larger than that of the through hole is fixed to the tip end portion of the valve shaft portion protruding to the opposite side of the portion, leaving a predetermined second gap between the first arm portion and the valve body. And
In an exhaust system for an engine configured to open at least two valve bodies assembled to the one arm portion to the upstream side of the upstream main passage,
Aligning at least two valve bodies assembled to the one arm portion in the axial direction of the rotary shaft;
A driving force for rotating the rotating shaft is applied only to one end of the rotating shaft;
Regarding the rotation direction of the rotation shaft, the first valve body which is the valve body on the side closer to one end of the rotation shaft on which the driving force acts among the at least two valve bodies assembled to the one arm portion is driven. An arm portion to which the first valve body is assembled and the second valve so as to be relatively closer to the valve opening than a second valve body which is a valve body far from one end of the rotating shaft on which a force acts; An angle difference is provided between the arm part to which the body is assembled,
When there is a request to open the flow path switching valve, the flow path switching valve is fully opened by driving the rotating shaft in the opening direction by the driving force and bringing the second valve body into contact with a stopper. Along with the fully open state of the flow path switching valve, a constant driving force is continuously applied to the rotating shaft in the valve opening direction,
When there is a request for closing the flow path switching valve thereafter, the rotary shaft is driven in the valve closing direction by the driving force. An upstream main passage for each cylinder connected to each cylinder;
A downstream main passage formed by joining upstream main passages of a plurality of cylinders;
A bypass passage branched from the upstream main passage,
A flow path switching valve that opens and closes the upstream main passage so that the exhaust discharged from each cylinder flows to the bypass passage, and shuts off the communication between the upstream main passages when closed.
In the flow path switching valve, a plurality of valve bodies that respectively open and close a plurality of valve openings formed side by side in a housing are attached to independent valve supports for each valve body. An arm portion to which the at least two valve bodies are assembled is integrally formed on a shaft portion that rotates integrally with a rotation shaft that is rotatably supported on the housing side,
Each of the valve bodies has a valve main body portion and a valve shaft portion standing up from the valve main body portion,
The valve opening is opened and closed by the peripheral edge of the valve main body contacting and leaving the valve seat at the upstream end of the valve opening,
A through hole in which the valve shaft portion is loosely fitted is formed in the arm portion of each valve body by having a predetermined first gap in a direction orthogonal to the axis of the valve shaft portion. A holding ring having an outer diameter larger than that of the through hole is provided at a distal end portion of the valve shaft portion protruding to the opposite side of the valve body portion, and a predetermined second gap is provided between the arm portion and the valve body for each valve body. Fixed, leaving
In an exhaust system for an engine configured to open at least two valve bodies assembled to an arm portion of each valve body to the upstream side of the upstream main passage,
Aligning at least two valve bodies assembled to the arm portion of each valve body in the axial direction of the rotary shaft;
A driving force for rotating the rotating shaft is applied only to one end of the rotating shaft;
Regarding the rotation direction of the rotary shaft, the first valve body which is the valve body on the side close to one end of the rotary shaft on which the driving force acts is selected among at least two valve bodies assembled to the arm portion for each valve body. An arm portion to which the first valve body is assembled so as to be relatively closer to the valve opening than a second valve body which is a valve body far from one end of the rotating shaft on which the driving force acts; An angle difference is provided between the arm part to which the two valve bodies are assembled,
When there is a request to open the flow path switching valve, the flow path switching valve is fully opened by driving the rotating shaft in the opening direction by the driving force and bringing the second valve body into contact with a stopper. Along with the fully open state of the flow path switching valve, a constant driving force is continuously applied to the rotating shaft in the valve opening direction,
When there is a request for closing the flow path switching valve thereafter, the rotary shaft is driven in the valve closing direction by the driving force.   The engine exhaust device according to claim 1 or 2, wherein the rotating shaft is made of a material having excellent creep resistance. Comprising a main catalyst interposed in the downstream main passage,
The engine exhaust system according to claim 1 or 2, wherein the operation condition in which the flow path switching valve is requested to open is when the main catalyst is activated.   The engine exhaust system according to claim 1 or 2, wherein the operating condition in which the flow path switching valve is requested to close is when the main catalyst is in an inactive state.   The engine exhaust system according to claim 1 or 2, wherein the first valve body is configured such that the first gap or the second gap is smaller than the second valve body.   3. The engine exhaust device according to claim 1, wherein the first valve body is configured such that the first gap and the second gap are smaller than those of the second valve body. 4. The exhaust passage of the engine
An upstream main passage for each cylinder connected to each cylinder of the engine;
A downstream main passage formed by joining the upstream main passages for each cylinder;
A bypass passage branched from the upstream main passage,
A plurality of flow path switching valves that open and close each upstream main passage by a driving force of a driving device so that exhaust discharged from each cylinder flows to the bypass passage;
The plurality of flow path switching valves are
A rotating shaft that is orthogonal to the upstream main passage and extends from the driving device to open and close at least two valve bodies by the driving device;
And at least two valve supports provided on the rotating shaft,
In the exhaust emission control device for an engine, the at least two valve bodies are attached to the at least two valve support bodies so as to be movable at a predetermined interval in a direction orthogonal to the rotation axis.
Of the at least two valve supports, the valve support close to the drive device is angled relatively closer to the seating position of the flow path switching valve in the upstream main passage than the valve support far from the drive device. Make a difference ,
When there is a request to open the flow path switching valve, the flow path switching valve is fully opened by driving the rotating shaft in the opening direction by the driving force and bringing a valve body far from the driving device into contact with a stopper. In addition, an exhaust system for an engine , wherein a constant driving force is continuously applied to the rotating shaft in the valve opening direction when the flow path switching valve is fully opened .

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