JP2009085099A - Engine exhaust control device - Google Patents

Abstract

An exhaust control device for an engine, in which an exhaust control valve capable of changing an opening area of an exhaust passage is provided in an exhaust passage forming means for forming an exhaust passage, enables good exhaust control.
An exhaust control valve 71 is a rotary valve in which a part of the exhaust control valve 71 projects into the exhaust passage 67 from the inner wall of the exhaust passage 67 when the valve is closed. The outer surface of the outer surface facing the upstream side and projecting from the inner wall is formed so that the amount of projection from the inner wall gradually increases from the upstream side to the downstream side of the exhaust passage 67.
[Selection] Figure 5

Description

  The present invention provides an exhaust passage in which an exhaust valve capable of opening and closing an exhaust valve port provided in a cylinder head facing the combustion chamber is disposed in the cylinder head so as to be capable of opening and closing, and forms an exhaust passage connected to the exhaust valve port The present invention relates to an exhaust control device for an engine in which an exhaust control valve capable of changing an opening area of the exhaust passage is disposed in a forming unit.

  An exhaust control device for a motorcycle engine in which an exhaust control valve, which is a butterfly valve, is arranged in an exhaust passage connected to an exhaust valve port is known from Patent Document 1.

Further, Patent Document 2 discloses that a butterfly valve is disposed in the flow passage, and the shape of the butterfly valve is bent or refracted to reduce the load torque at the time of opening and closing the valve.
JP-A-2-049936 JP-A-4-214936

  However, in the one disclosed in Patent Document 1, a butterfly valve is arranged at substantially the center of the flow passage, and the valve main body and the shaft are always exposed in the flow passage. Reduced by the valve. On the other hand, in the one disclosed in Patent Document 2, the shape of the butterfly valve is bent or refracted to reduce the load torque, but the reduction of the passage cross-sectional area is the same as that disclosed in Patent Document 1. .

  In addition, since the butterfly valves of Patent Documents 1 and 2 change the shielding area at the center of the passage, the space between the inner wall of the passage and the butterfly valve is narrow, and turbulent flow occurs when the flow velocity is high. It becomes difficult to control.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine exhaust control device that enables good exhaust control.

  In order to achieve the above object, the invention according to claim 1 is characterized in that an exhaust valve capable of opening and closing an exhaust valve port provided in the cylinder head facing the combustion chamber is disposed in the cylinder head so as to be openable and closable. In an exhaust control device for an engine, in which an exhaust control valve capable of changing an opening area of the exhaust passage is disposed in an exhaust passage forming means that forms an exhaust passage connected to an exhaust valve port. When the exhaust control valve is closed, A rotary valve configured to partially protrude from the inner wall of the exhaust passage into the exhaust passage, and at least from the inner wall of the outer surface of the rotary valve in a closed state that protrudes into the exhaust passage and faces the upstream side. The projecting tip side outer surface is formed so as to gradually increase the projecting amount from the inner wall from the upstream side to the downstream side of the exhaust passage.

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the rotary valve has a rotation axis at a position offset from the center of the exhaust passage and is centered on the rotation axis. The valve main body having a cylindrical outer surface shape is characterized in that a passage portion constituting a part of the exhaust passage is formed so as to cut out a part of the valve main body when fully opened.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, at least a portion of the exhaust passage where the rotary valve is disposed has an elliptical cross-sectional shape, and the passage The portion is formed in the valve main body so as to be flush with a part of the circumferential direction of the inner wall of the exhaust passage when fully open.

  According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the invention, the rotary valve has a rotation axis at a position offset from the center of the exhaust passage and rotates to the exhaust passage forming means. The inner rotor is configured to be supported, and the outer rotor is linked to and coupled to the inner rotor so as to operate behind the inner rotor, and is rotatably supported by the inner rotor. To do.

  According to a fifth aspect of the present invention, in addition to the configuration of the first aspect of the invention, a plurality of rotary valves having rotational axes at positions offset from the center of the exhaust passage are linked and connected to each other to form the exhaust passage. It is arrange | positioned at a formation means, It is characterized by the above-mentioned.

  In addition to the configuration of the invention described in claim 1, the invention according to claim 6 is a circle in which the rotary valve has a rotation axis at the center of the exhaust passage and is larger in diameter than the inner diameter of the exhaust passage. A valve main body configured in a columnar shape is formed by forming a passage hole extending along one diameter line of the valve main body so as to form a shielding portion on both sides thereof, and the inner diameter of the passage hole is formed in the rotary valve. When fully opened, the exhaust passage is set to be flush with the inner surface of the exhaust passage.

  According to the first aspect of the present invention, the exhaust control valve is a rotary valve, and the rotary valve projects a part from the inner wall of the exhaust passage into the exhaust passage when the valve is closed, and is in the closed state. The outer surface of the rotary valve that protrudes into the exhaust passage and faces the upstream side gradually increases the amount of protrusion from the inner wall as it protrudes from the inner wall toward the downstream side from the upstream side of the exhaust passage. Therefore, even when the rotary valve is closed, the opening area of the exhaust passage can be made relatively large, and even when the exhaust flow rate is high, the occurrence of turbulent flow on the rotary valve surface can be prevented. Good exhaust control by opening and closing can be realized.

  According to the invention described in claim 2, since the valve main body of the rotary valve has a cylindrical outer surface shape coaxial with the rotation axis at a position offset from the center of the exhaust passage, the workability of the rotary valve is improved. Can be increased.

  According to the third aspect of the present invention, at least a portion of the exhaust passage where the rotary valve is disposed is formed to have an elliptical cross-sectional shape, and the passage portion of the rotary valve is formed on the inner wall of the exhaust passage when fully opened. Since the valve main body is formed so as to be flush with a part of the circumferential direction, the passage portion is formed in the valve main body while maintaining the cross-sectional area of the exhaust passage and the cross-sectional area shielded by the rotary valve. It is possible to increase the strength of the rotary valve by enlarging the remaining portion excluding the portion to be removed.

  According to the invention of claim 4, the rotary valve is coupled to and coupled to the inner rotor so as to be operated behind the inner rotor, and the inner rotor is rotatably supported by the exhaust passage forming means. Since it is composed of an outer rotor that is rotatably supported by the inner rotor, the inner rotor passage is designed so that a part of the area of the passage required for the entire rotary valve is borne by the inner rotor. Can be made relatively small to increase the strength of the inner rotor and increase the strength of the entire rotary valve by reinforcing the outer rotor with the inner rotor.

  According to the fifth aspect of the present invention, the plurality of rotary valves having the rotation axis at the position offset from the center of the exhaust passage are interlocked and connected to each other so as to be arranged in the exhaust passage forming means. The responsiveness can be increased by increasing the speed of changing the cross-sectional area of the exhaust passage by closing each rotary valve while increasing the strength of each rotary valve by setting the cross-sectional area of each passageway in each rotary valve small. it can.

  According to the sixth aspect of the present invention, when the rotary valve is closed, the shielding portions on both sides of the passage hole of the rotary valve project simultaneously from the inner wall of the exhaust passage into the exhaust passage. It is possible to increase the response speed by increasing the speed of changing the cross-sectional area of the passage.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 7 show a first embodiment of the present invention. FIG. 1 is a right side view of a main part of a motorcycle, and FIG. 2 is a vertical left side view of a four-cycle engine. FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 2, FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, and FIG. 5 is a fully opened (a) and fully closed position of the rotary valve. FIG. 6 is a cross-sectional view showing the state of (b) along line 5-5 in FIG. 4, FIG. 6 is a block diagram showing a control system of the rotary valve, and FIG. 7 is a diagram showing a change in output accompanying a change in the opening of the rotary valve. is there.

  1, a motorcycle body frame F, which is a small vehicle, includes a head pipe 15 at its front end, a pair of left and right main frames 16 extending rearwardly downward from the head pipe 15, and the main frames 16. A pair of left and right pivot plates 17 connected to the rear and extending downward, a down frame 18 extending downward from the head pipe 15, and a pair of left and right connecting the lower end of the down frame 18 and the pivot plates 17. A four-cycle water-cooled single cylinder engine body 24A is surrounded by the main frame 16, the pivot plate 17, the down frame 18 and the lower frame 19 ... It is supported by the vehicle body frame F so as to be arranged in a space. Further, radiators 25... Divided into left and right sides of the down frame 18 are arranged in front of the engine main body 24 </ b> A, and these radiators 25 are supported by the down frame 18.

  Referring also to FIG. 2, the engine body 24A includes a crankcase 27 that uses a crankshaft 26 that has an axis extending in the left-right direction of the motorcycle, and a cylinder bore 28. A cylinder block 29 coupled to the upper part, a cylinder head 30A coupled to the upper part of the cylinder block 29, and a head cover 31 coupled to the upper part of the cylinder head 30A are provided. Moreover, when the engine body 24A is mounted on the vehicle body frame F, the cylinder block 29 is coupled to the crankcase 27 so that the axis CB of the cylinder bore 28 is slightly inclined upward.

  A piston 32 is slidably fitted to the cylinder bore 28, and the piston 32 is connected to the crankshaft 26 via a connecting rod 33. A combustion chamber 34 is formed between the cylinder block 29 and the cylinder head 30A so that the top of the piston 32 faces.

  By the way, the crankshaft 26 rotates in the rotational direction indicated by the arrow 35 in accordance with the reciprocating sliding of the piston 32 in the cylinder bore 28. The axis CB of the cylinder bore 28 is more than the axis CC of the crankshaft 26. By setting the axis CB of the cylinder bore 28 to be offset with respect to the axis CC of the crankshaft 26 in this way, the piston 32 on the inner surface of the cylinder bore 28 is set. Wear due to sliding contact can be suppressed, and the cylinder block 29 and the combustion chamber 34 can be prevented from becoming high temperature due to the wear.

  The cylinder head 30A is provided with a pair of intake valve ports 36 and a pair of exhaust valve ports 37 facing the combustion chamber 34. A pair of intake valves 38 that individually open and close the intake valve ports 36 and a pair of exhaust valves 39 that individually open and close the exhaust valve ports 37 are disposed in the cylinder head 30A so as to be openable and closable. The two intake valves 38 are energized in the valve closing direction by the valve springs 40, and the exhaust valves 39 are energized in the valve closing direction by the valve springs 41, respectively.

  With further reference to FIG. 3, a valve operating device 44 for opening and closing the intake valves 38 and the exhaust valves 39 is accommodated between the cylinder head 30A and the head cover 31. The valve operating device 44 has an axis parallel to the crankshaft 26 and is disposed above the intake valves 38 and is rotatably supported by the cylinder head 30A, and the camshaft. , And a pair of valve lifters 46 interposed between the intake valves 38 and a pair of exhaust side cams 49 provided on the camshaft 45, respectively. Thus, the exhaust valve 39 is paired with a pair of rocker arms 47 that open and close to form an SOHC type.

  The valve lifters 46 are formed in a bottomed cylindrical shape with the upper end as a closed end, and are fitted into the cylinder head 30A so as to slide in the axial direction coaxial with the operation axis of the intake valves 38. The The upper ends of the stems 38a of the intake valves 38 are in contact with the inner surfaces of the closed ends of the valve lifters 46, and the intake cams 48 are in contact with the outer surfaces of the closed ends of the valve lifters 46. A plug insertion cylinder 50 is attached to the cylinder head 30A by inserting a spark plug (not shown) that is screwed into the cylinder head 30A so that the front end faces the combustion chamber 34. The plug insertion cylinder 50 is attached to the cylinder head 30A. The two rocker arms 47 arranged on both sides of the camshaft 45 are rotatably supported by a rocker shaft 51 having an axis parallel to the camshaft 45 and supported by the cylinder head 30A. Moreover, rollers 52 which are in rolling contact with the exhaust side cams 49 are respectively pivotally supported at one end portions of the rocker arms 47, and the other end portions of the rocker arms 47 are the stems 39a of the exhaust valves 39. It is contact | abutted at an upper end, respectively.

  In such a SOHC type valve gear 44, the angle α formed by the operation axes of the intake valves 38 and the exhaust valves 39 is set to be relatively small on the projection onto the plane orthogonal to the axis of the crankshaft 26. It is possible to reduce the size of the cylinder head 30A by arranging the intake valves 38 and the exhaust valves 39 closer to each other.

  The rotational power of the crankshaft 26 is transmitted by the timing transmission mechanism 53 at a reduction ratio of 1/2 to one end of the camshaft 45, which is the left end when the engine body 24A is mounted on the vehicle body frame F. The timing transmission mechanism 53 includes a drive sprocket (not shown) provided on the crankshaft 26 and a driven sprocket 55 fixed to one end of the camshaft 45. Wrapped around. In addition, the cylinder block 29 and the cylinder head 30A are provided with a cam chain chamber 57 for running the cam chain 56. The cam chain chamber 57 is mounted on the vehicle body frame F of the engine body 24A. 29 and the left end of the cylinder head 30A.

  The cylinder head 30A is provided with a single intake port 58 that communicates in common with the intake valve ports 36, and forms a part of the intake port 58 so as to be rearward from the rear side surface of the cylinder head 30A. An intake side connection pipe portion 59 provided integrally with the cylinder head 30A so as to project is formed with an intake passage 60 communicating with the intake port 58, and a throttle body 61 disposed behind the cylinder head 30A has an insulator. 62 is connected. A throttle valve 63 that changes the opening area of the intake passage 60 is rotatably supported on the throttle body 61, and a fuel injection valve 64 that injects fuel toward the intake port 58 is attached to the throttle body 61.

  Further, the cylinder head 30A is provided with a single exhaust port 65 that communicates in common with the exhaust valve ports 37, and a part of the exhaust port 65 is formed so that the front side surface of the cylinder head 30A is forward. An exhaust-side connecting pipe portion 66 that protrudes into the cylinder head 30A is provided integrally with the cylinder head 30A. An exhaust pipe 68 is connected to the exhaust side connection pipe portion 66 so as to form an exhaust passage 67 including the exhaust port 65, and the exhaust port 65 passes through the upstream end. The exhaust muffler 69 (see FIG. 1) is connected. Thus, a part of the cylinder head 30A integrally having the exhaust side connecting pipe portion 66 and the exhaust pipe 68 constitute an exhaust passage forming means 70 that cooperates to form an exhaust passage 67.

  The exhaust side connecting pipe portion 66 has a straight portion 65aa in part, but is integrally connected to the cylinder head 30A so that a part of the exhaust port 65 forms a bent portion 65a as a whole. The bent portion 65a is bent in the horizontal direction so as to protrude in the right direction in this embodiment in the left-right direction of the motorcycle when the engine body 24A is mounted on the vehicle body frame F. A part of the vehicle body frame F is formed so as to avoid the down frame 18 disposed in front of the cylinder head 30A, and is formed to bend to the left behind the down frame 18 and integrated with the cylinder head 30A. To be connected to.

  The upstream end of the exhaust pipe 68 is connected to the exhaust side connection pipe section 66. The exhaust pipe 68 is formed in the exhaust side connection pipe section 66 as shown in FIG. A hanging tube portion 68a that extends slightly to the left in the extending direction and then extends downward so as to wrap around the front of the down frame 18, and is bent to the right from the lower end of the hanging tube portion 68a and extends obliquely upward to the right. A first ascending pipe portion 68b and a second ascending pipe portion 68c that bends leftward from the rear end of the first ascending pipe portion 68b and extends rearward as it slightly rises toward the center in the width direction of the vehicle body frame F. .

  Referring also to FIG. 4, the curved cross-sectional area of the curved portion 65 a formed by a curved portion, that is, a part of the exhaust port 65, which is disposed at a position closest to the exhaust valve port 37. The rotary valve 71 is an exhaust control valve. The rotary valve 71 is disposed in the straight portion 65aa of the bent portion 65a.

  The rotary valve 71 is configured to change a partial passage cross-sectional area inside the bent portion 65a by projecting a part from the inner wall of the exhaust port 65 in the exhaust passage 67 into the exhaust port 65 when the rotary valve 71 is closed. The cylinder head 30A is disposed on the exhaust side connecting pipe portion 66 and is offset from the center CL of the bent portion 65a toward the inside of the curve, in this embodiment, on the opposite side to the down frame 18. At the position offset from the center CL of the exhaust port 65 toward the cam chain chamber 57, a rotary valve 71 having a rotation axis CR oriented in the vertical direction substantially parallel to the axis CB of the cylinder bore 28 is formed in the exhaust side connecting pipe 66. Arranged.

  When the rotary valve 71 is fully opened as shown in FIGS. 4 and 5A, a part of the exhaust port 65 in the exhaust passage 67 is formed on a valve main body 72 having a cylindrical outer surface centered on the rotation axis CR. The valve body 72 is formed so as to cut out a part of the valve main body 72. At both ends of the valve main body 72, rotation shaft parts 72a and 72b that are coaxial with the rotation axis CR are formed. Projecting coaxially and integrally. When the rotary valve 71 is closed, the outer surface of the rotary valve 71, that is, a part of the outer surface of the valve main body 72 protrudes from the inner wall of the exhaust port 65 in the exhaust passage 67, as shown in FIG. . Moreover, since the valve main body 72 is cylindrical, the outer surface of the rotary valve 71 in the closed state protrudes into the exhaust passage 67 and faces the upstream side at least from the inner wall protruding from the inner wall. Then, since the rotation axis CR of the rotary valve 71 is located at a position crossing the exhaust passage 67, the protruding front end side outer surface of the rotary valve 71 that protrudes into the exhaust passage 67 and faces the upstream side is projected from the inner wall. Is gradually increased from the upstream side of the exhaust passage 67 toward the downstream side, and the portion facing the upstream side of the protruding tip side is bent in the same direction as the bending direction of the exhaust port 65 in the exhaust passage 67. .

  The rotary valve 71 is accommodated in a valve housing 74 that is provided integrally with an exhaust-side connecting pipe portion 66 that is integral with the cylinder head 30A. The valve housing 74 includes an accommodating portion 74a that accommodates the valve main body 72 in a rotatable manner, and a box-shaped portion 74b that is integrally connected to an upper portion of the accommodating portion 74a. It is formed in a rectangular shape extending from the portion 74a to the opposite side to the cam chain chamber 57 and having an upper portion opened.

  The housing portion 74a is formed with a housing hole 75 that crosses the straight portion 65aa of the bent portion 65a of the exhaust port 65 at a portion near the cam chain chamber 56, and a smaller diameter than the housing hole 75. A bottomed lower support hole 76 that is coaxially connected to the hole 75 is provided, and an annular lower support surface 77 that faces upward is formed between the accommodation hole 75 and the lower support hole 76. The upper end of the accommodating hole 75 is opened in a flat coupling surface 78 formed at the upper end of the accommodating portion 74 a so as to face the box-shaped portion 74 b, and the coupling surface 78 has a valve main body of the rotary valve 71. A holding member 79 that sandwiches 72 between the lower support surface 77 and the lower support surface 77 is coupled by a plurality of bolts 80, 80, for example.

  That is, the valve main body 72 is inserted into the receiving hole 75 from above so that the rotation shaft portion 72a is rotatably fitted in the lower support hole 76, and holds the valve main body 72 from above. In this way, the pressing member 79 is fastened to the coupling surface 78. In addition, the holding member 79 is provided with an upper support hole 81 through which the rotation shaft portion 72b of the valve main body 72 is pivotably passed. An annular seal is provided between the holding member 79 and the rotation shaft portion 72b. A member 82 is interposed.

  A return spring 83 is provided between the rotary shaft portion 72 b and the pressing member 79 of the rotary valve 71, and the rotary shaft portion 72 b, that is, the rotary valve 71 is opened by the spring force of the return spring 83, that is, As shown in FIG. 5, the passage portion 73 is biased to the rotational position side that is flush with the inner surface of the exhaust port 65.

  The upper end surface of the valve housing 74, that is, the upper end surface of the box-shaped portion 74b is formed so as to be flush with the coupling surface 84 to the head cover 31 of the cylinder head 30A. A lid member 86 that forms an operation chamber 85 is fastened between the valve housing 74 and the valve housing 74.

  In the working chamber 85, a drum 87 is fixed to a rotating shaft portion 72b of the rotary valve 71, and a closed side cable 88 for rotating the rotary valve 71 to the closing side when towing is attached to the drum 87. And one end of an open-side cable 89 that rotates the rotary valve 71 to the valve-opening side when towed are wound around and engaged with each other.

  The closing cable 88 and the opening cable 89 are formed by inserting inner cables 88b and 89b movably through the outer cables 88a and 89a, and one end portions of the outer cables 88a and 89a are separated from the drum 87. Thus, one end of the inner cables 88b and 89b fixed to the side wall of the box-shaped portion 74b and projecting from one end of the outer cables 88a and 89a is connected to the drum 87.

  On the other hand, the other ends of the closing side cable 88 and the opening side cable 89 are connected to an actuator 90 having a forward and reverse electric motor and supported by the vehicle body frame F. By the actuator 90, the closing side cable 88 is connected. By pulling 88, the rotary valve 71 rotates in the valve closing direction, and by pulling the opening-side casing 89, the rotary valve 71 rotates in the valve opening side.

  By the way, on the front side surface of the cylinder head 30A, water for guiding cooling water from the water jacket 91 provided on the cylinder block 29 and the cylinder head 30A to the radiator 25. An outlet 92 is provided, and the water outlet 92 is disposed on the side opposite to the cam chain chamber 57 with respect to the exhaust port 65.

  In FIG. 1, a water pump 94 driven by power transmitted from the crankshaft 26 is attached to the outer surface of the right cover 93 fastened to the right side surface of the crankcase 27. Is connected to a pipe 95 for guiding cooling water from the lower part of the radiator 25. On the other hand, the cooling water discharged from the water pump 94 is introduced into the lower part of the water jacket 91 through the right cover 93, the crankcase 27 and the cylinder block 29, and is connected to the upper part of the water jacket 91. The water outlet 92 provided in the cylinder head 30 </ b> A and the upper portions of the radiators 25 are connected via a pipe 96.

  In FIG. 6, the operation of the actuator 90 is controlled by a control unit 98, and the control unit 98 includes an engine speed NE detected by an engine speed detector 99 and a gear position detector 100. The detected gear position GP of the transmission is input, and the control unit 98 controls the operation of the actuator 90 to open and close the rotary valve 71 based on the engine speed NE and the gear position GP. It should be noted that the throttle opening may be used instead of the engine speed NE, or both the engine speed NE and the throttle opening may be used.

  Thus, the control unit 98 fully opens the rotary valve 71 during high-speed operation of the engine, and closes more than half (for example, 57%) of the cross-sectional area of the exhaust port 65 in the exhaust passage 67 during medium-low speed operation of the engine. The actuator 90 is controlled to be in a fully closed state.

  The control unit 98 determines whether or not the motorcycle is decelerating based on at least one of the engine speed NE and the throttle opening and the gear position. When it is determined that the motorcycle is decelerating, the engine brake is applied. Accordingly, the actuator 90 is operated so as to close the rotary valve 71.

  Further, the control unit 98 determines whether or not the motorcycle is suddenly accelerating based on at least one of the engine speed NE and the throttle opening and the gear position. The actuator 91 is operated so as to temporarily close the rotary valve 71 in order to create an output reservoir.

  Next, the operation of the first embodiment will be described. Of the exhaust passage 67 formed by the exhaust passage formation means 70, the cross-sectional area of the curved portion at the curved portion 65a of the exhaust port 65 closest to the exhaust valve port 37. Among them, the partial passage cross-sectional area inside the curve is changed by the rotary valve 71, so that the rotary valve 71 is arranged at a portion where the exhaust flow velocity is close to the combustion chamber 34 and is fast even inside the curve. The exhaust control effect can be maximized without increasing the size of 71. Further, when the rotary valve 71 is closed, the exhaust gas flows only at the outer side of the bent portion 65a where the exhaust flow rate is fast, and the rotary valve 71 can reduce the exhaust amount while maintaining the exhaust flow rate. Disturbance of the exhaust flowing outside can be mitigated at the bent portion to suppress the generation of turbulent flow and good exhaust control can be achieved. Further, the rotary valve 71 is disposed at a position close to the combustion chamber 34, and the pressure control in the combustion chamber 34 by the rotary valve 71 and the opening timing of the exhaust valves 39 and the intake valves 38 are overlapped. Blow-through can be suppressed.

  In addition, the bent portion 65a of the exhaust port 65 has a straight portion 65aa extending in a straight line at a part thereof, and the rotary valve 71 is disposed on the straight portion 65aa, thereby simplifying the shape of the rotary valve 71. Thus, processing of the rotary valve 71 can be facilitated and exhaust control by the rotary valve 71 can be improved.

  Further, since the rotary valve 71 is flush with the inner surface of the exhaust port 65 in the exhaust passage 67 when fully opened, the rotary valve 71 reduces the cross-sectional area of the exhaust port 65 in the exhaust passage 67 when the rotary valve 71 is fully opened. There is no. A control unit 98 that controls an actuator 90 that opens and closes the rotary valve 71 opens the rotary valve 71 when the engine is operating at a high speed, and the passage cross-sectional area of the exhaust port 65 in the exhaust passage 67 when the engine is operating at a medium and low speed. The actuator 90 is controlled so that more than half (for example, 57%) of the actuator is in a fully closed state.

  Here, when the exhaust port 65 is in a fully open state, and when the exhaust port 65 is in a fully closed state in which more than half (for example, 57%) of the passage cross-sectional area of the exhaust port 65 is closed, the engine output changes in the operating state of the engine. As shown in FIG. 7, the exhaust gas from the combustion chamber 34 is better discharged without reducing the cross-sectional area of the exhaust port 65 in the exhaust passage 67 during high speed operation. It is possible to improve the combustion efficiency by effectively injecting air, and during the low-speed operation, the discharge of the exhaust from the combustion chamber 34 is delayed to prevent the blowout of fresh air, and the pressure in the combustion chamber 34 is increased. Thus, the engine output can be improved.

  Since the control unit 98 controls the operation of the actuator 90 to open and close the rotary valve 71 based on at least one of the engine speed NE and the throttle opening and the gear position, the control unit 98 represents the state of the combustion chamber 34. The optimal opening / closing control of the rotary valve 71 can be performed in accordance with at least one of the index, that is, the throttle opening degree and the engine speed NE, and the gear position of the transmission.

  Further, the control unit 98 determines whether or not the motorcycle is decelerating, and when it determines that the motorcycle is decelerating, the actuator 90 is operated so as to close the rotary valve 71 so as to apply the engine brake. The engine brake can be applied at the time of deceleration by the rotary valve 71.

  Further, the control unit 98 determines whether or not the motorcycle is suddenly accelerating, and when it is determined that the motorcycle is suddenly accelerating, the actuator 90 is operated so as to temporarily close the rotary valve 71 so as to create a reservoir for engine output. Therefore, the rotary valve 71 can be temporarily closed at the time of rapid acceleration, and the output can be temporarily reduced without impairing the acceleration operation feeling, so that the wheel grip can be improved.

  Incidentally, the rotary valve 71 has a rotation axis CR at a position offset from the center Cl of the exhaust port 65 so that a part of the rotary valve 71 projects into the exhaust port 65 from the inner wall of the exhaust port 65 when the valve is closed. In addition, even when the rotary valve 71 is closed, the opening area of the exhaust port 65 can be made relatively large. In addition, the outer surface of the rotary valve 71 in the closed state that protrudes into the exhaust passage 67 and faces the upstream side protrudes from the inner wall at least from the inner wall, in this embodiment, from the inner wall. Is gradually increased from the upstream side of the exhaust passage 67 toward the downstream side, and the portion facing the upstream side of the protruding tip side is bent in the same direction as the bending direction of the exhaust port 65 in the exhaust passage 67. Even when the exhaust flow rate is high, as shown by the arrow in FIG. 5 (b), the exhaust gas is allowed to flow smoothly along the surface of the rotary valve 71 to prevent the occurrence of turbulent flow on the surface of the rotary valve 71. Good exhaust control by opening and closing 71 can be realized.

  Further, the rotary valve 71 has a valve body 72 having a cylindrical outer surface shape centered on the rotation axis CR, and a passage portion 73 that constitutes a part of the exhaust port 65 when the valve is fully opened. It is formed by notching and the workability of the rotary valve 71 can be improved.

  Further, the rotary valve 71 can change the opening area of the exhaust port 65 provided in the cylinder head 30A, and is offset from the center CL of the exhaust port 65 toward the cam chain chamber 57 side. Since the rotary valve 71 that is relatively heavy is disposed in the cylinder head 30A, the rotary valve 71 is disposed on the side near the cam chain chamber 57 that is a cavity. Since it is disposed in the cylinder head 30A, the weight balance of the engine body 24A can be set appropriately, and the rotary valve 71 does not need to be replaced when the exhaust pipe 68 is replaced.

  Moreover, since the rotary valve 71 is disposed on the exhaust side connecting pipe portion 66 on the side opposite to the down frame 18, interference with the down frame 18 of the rotary valve 71 can be avoided. Further, the rotary valve 71 is disposed in the cylinder head 30A on the side close to the cam chain chamber 57. The valve operating device 44 includes a camshaft 45 disposed above the intake valves 38, and the cam. A pair of intake side cams 48 provided on the shaft 45 and a pair of valve lifters 46 respectively interposed between the intake valves 38 and a pair of exhaust side cams 49 provided on the camshaft 45 are driven to swing. Thus, the exhaust valve 39 has a pair of rocker arms 47 that open and close to form an SOHC type, and the rotary valve 71 corresponds to the cam chain chamber 57 to the camshaft 45. There is no interference with the driven sprocket 55 provided.

  Further, a water outlet 92 for guiding the cooling water from the cylinder head 30A to the radiator 25... Disposed on the front side of the engine body 24A is located on the opposite side of the exhaust port 65 from the cam chain chamber 57 and in front of the cylinder head 30A. Since it is provided on the side surface, the rotary valve 71 can be arranged so as not to interfere with the pipe 96 connected to the water outlet 92.

  By the way, in the valve gear 44 that opens and closes the intake valves 38... And the exhaust valves 39..., The exhaust cams 49 provided on the camshaft 45 disposed above the intake valves 38. It is linked to and connected to the exhaust valve 39 through rocker arms 47 that swing when driven, and such a valve operating device 44 is an intake valve on a plan view orthogonal to the axis of the crankshaft 26. 38 and the exhaust valve 39 can be set to be relatively small in angle α, and the intake valve 38 and the exhaust valve 39 are arranged closer to each other to reduce the size of the cylinder head 30A. However, since the rotation axis CR of the rotary valve 71 is set substantially parallel to the axis CB of the cylinder bore 28 in the cylinder block 29, the cylinder bore 28 and the cylinder It can be made compact engine body 24A in a direction orthogonal to the axis of the link shaft 26.

  Moreover, the rotary valve 71 is rotatably accommodated in a valve housing 74 that is integrally provided in the exhaust side connecting pipe portion 66 that is integral with the cylinder head 30A. Therefore, a valve housing that accommodates the rotary valve 71 is specially prepared. Is unnecessary, and the number of parts can be reduced.

  When the engine body 24A is mounted on the vehicle body frame F, the exhaust-side connecting pipe portion 66 is formed such that a part of the exhaust port 65 forms a bent portion 65a that bulges rightward and curves horizontally in the motorcycle. Since the rotary valve 71 is accommodated in the valve housing 74 with its rotation axis CR oriented in the vertical direction, the cylinder head 30A of the valve housing 74 is connected to the cylinder head 30A. It is possible to prevent the rotation shaft portions 72a and 72b of the rotary valve 71 from separating from the combustion chamber 34 and to prevent the rotation shaft portions 72a and 72b from reaching a high temperature. Further, the drum 87, which is a drive mechanism for driving the rotary valve 71, the closing side cable 88, the opening side cable 89, and the like are arranged on the upper portion of the valve housing 74, whereby the drum 87, the closing side cable 88 and the opening side cable 89 are arranged. Etc. can be easily protected from stepping stones from below.

  Further, the valve housing 74 is provided integrally with the outside-side connecting pipe portion 66 integral with the cylinder head 30A so that the rotary valve 71 can be assembled from above and is opened upward. However, since the cylinder head 30A is formed flush with the coupling surface 84 of the cylinder head 30A to the head cover 31, the workability of the valve housing 74 is improved and the assembly of the rotary valve 71 of the valve housing 74 is facilitated. Can do.

  Further, the engine main body 24A is configured such that the axis CB of the cylinder bore 28 is offset from the axis CC of the crankshaft 26 in the rotational direction 35 of the crankshaft 26, so that the piston to the inner surface of the cylinder bore 28 is arranged. The friction caused by the sliding contact of 32 can be suppressed, the temperature of the cylinder block 29 and the combustion chamber 34 can be prevented from becoming higher, and the thermal effect on the rotary valve 71 disposed in the exhaust port 65 can be reduced. it can.

  8 to 10 show a second embodiment of the present invention. FIG. 8 is a longitudinal left side view of a four-cycle engine corresponding to FIG. 2, and FIG. 9 is an enlarged sectional view taken along line 9-9 in FIG. FIG. 10 is an enlarged view of the main part of FIG. 8 for explaining the state when the rotary valve is fully opened (a) and fully closed (b).

  It should be noted that portions corresponding to the first embodiment are only given the same reference numerals for illustration, and detailed description thereof is omitted.

  The engine body 24B includes a crankcase 27 that rotatably uses a crankshaft 26 having an axis extending in the left-right direction of the motorcycle, and a cylinder block 29 that has a cylinder bore 28 and is coupled to the upper portion of the crankcase 27. The cylinder head 30B is coupled to the upper portion of the cylinder block 29, and the head cover 31 is coupled to the upper portion of the cylinder head 30B.

  The cylinder head 30B is provided with a single exhaust port 101 that communicates in common with the exhaust valve ports 37, and forms a part of the exhaust port 101 so as to protrude forward from the front side surface of the cylinder head 30B. The exhaust-side connecting pipe portion 102 is provided integrally with the cylinder head 30B. An exhaust pipe 104 that forms an exhaust passage 103 including the exhaust port 101 in cooperation with the exhaust side connection pipe 102 is connected to the exhaust side connection pipe 102 so that an upstream end of the exhaust pipe 104 communicates with the exhaust port 101. In addition, a part of the cylinder head 30B integrally having the exhaust-side connecting pipe portion 102 and the exhaust pipe 104 constitute exhaust passage forming means 105 that forms the exhaust passage 103 in cooperation.

  The exhaust-side connecting pipe portion 102 is integrally connected to the cylinder head 30B so that the bent portion 101a is formed by a part of the exhaust port 101, and the bent portion 101a is connected to the body of the engine main body 24A. When mounted on the frame F, it bulges upward and curves upward and downward, and the exhaust-side connecting pipe portion 102 is lowered between a pair of left and right lower frames 19 and 19 constituting a part of the vehicle body frame F. And is integrally connected to the cylinder head 30B.

  In the exhaust passage 103, a curved portion disposed at a position closest to the exhaust valve port 37, that is, a partial passage cross-sectional area inside the bent portion 101a of the exhaust port 101 is changed by a rotary valve 71 which is an exhaust control valve. I'm damned.

  The rotary valve 71 is configured to change a partial passage cross-sectional area inside the curved portion 65a by projecting a part from the inner wall of the exhaust port 101 in the exhaust passage 103 into the exhaust port 101 when the rotary valve 71 is closed. The cylinder head 30B is disposed on the exhaust side connecting pipe portion 102, and has a rotation axis CR oriented in the left-right direction of the motorcycle at a position offset from the center CL of the bent portion 101a. Arranged in the exhaust side connecting pipe 102.

  When the rotary valve 71 is fully opened as shown in FIGS. 8 and 10A, a part of the exhaust port 101 in the exhaust passage 103 is formed on a valve main body 72 having a cylindrical outer surface shape centering on the rotation axis CR. Is formed so that a part of the valve main body 72 is cut away. When the rotary valve 71 is closed, the outer surface of the rotary valve 71, that is, a part of the outer surface of the valve main body 72 protrudes from the inner wall of the exhaust port 101 in the exhaust passage 103, as shown in FIG. . Moreover, since the valve main body 72 has a cylindrical shape, the amount of protrusion from the inner wall of the distal outer surface of the portion of the outer surface of the rotary valve 71 that protrudes from the inner wall of the exhaust port 101 when the valve is closed and faces the upstream side is: It gradually increases from the upstream side to the downstream side of the exhaust port 101.

  The rotary valve 71 is accommodated in a valve housing 106 that is provided integrally with the exhaust-side connecting pipe portion 102 that is integral with the cylinder head 30B. The valve housing 106 is provided integrally with the exhaust-side connecting pipe 102 so as to extend in the left-right direction of the motorcycle, and a lid member 107 is fastened to the valve housing 106.

  Thus, the rotary valve 71 is driven to open and close by the actuator 90 (see the first embodiment) as in the first embodiment.

  According to the second embodiment, an exhaust-side connecting pipe in which a valve housing 106 that houses a rotary valve 71 that controls an opening area inside a bent exhaust port 101 that is bent in the vertical direction is integrally provided on the cylinder head 30B. Since it is integrally formed with the portion 102, the space between the cylinder head 30B and the cylinder block 29 and the exhaust side connecting pipe portion 102 is effectively used to avoid interference with the cylinder head 30B and the cylinder block 29. The housing 106 can be disposed, and the rotary valve 71 can be separated from the combustion chamber 34 to prevent the rotary valve 71 from reaching a high temperature.

  Further, when a plurality of exhaust ports 101 are arranged in parallel with the cylinder head 30B, the plurality of rotary valves 71 can be rotated by a single rotation shaft, reducing the number of parts and each exhaust port 101. The exhaust control structure can be simplified.

  FIG. 11 is a simplified front view of the cylinder head and cylinder block of the third embodiment, and FIG. 12 is a sectional view taken along line 12-12 of FIG. 11, and the same parts as those in the first and second embodiments are the same. These are only shown with reference numerals and detailed description is omitted.

  An exhaust side connecting pipe portion 111 that forms a part of the exhaust port 110 and protrudes forward is integrally formed on the front side surface of the cylinder head 30C that constitutes a part of the engine body 24C and is coupled to the cylinder block 29. Provided. The exhaust side connection pipe portion 111 is connected so that an upstream end of an exhaust pipe 113 that forms an exhaust passage 112 including the exhaust port 110 in cooperation with the exhaust side connection pipe portion 111 communicates with the exhaust port 110. In addition, a part of the cylinder head 30 </ b> C integrally having the exhaust side connecting pipe portion 111 and the exhaust pipe 113 constitute exhaust passage forming means 114 that cooperates to form the exhaust passage 112.

  The exhaust side connecting pipe portion 111 is integrally connected to the cylinder head 30C so that the bent portion 110a is formed by a part of the exhaust port 110, and the bent portion 110a is provided on either the left or right side of the motorcycle. On the other hand, it is bent so as to swell upward (to the right in this embodiment), and is disposed at a position closest to the exhaust valve port 37 (see the first and second embodiments) in the exhaust passage 112. The curved sectional area of the curved portion 110a, that is, the curved portion 110a of the exhaust port 110 is changed by the rotary valve 71 which is an exhaust control valve.

  The rotational axis CR of the rotary valve 71 is set so as to be inclined in the vertical direction so as to be located on the left or right side (right side in this embodiment) of the vehicle as it goes downward. Inside the curved portion of the portion 110a, the valve housing 115 is integrally accommodated in the exhaust side connecting pipe portion 111 so as to be rotatable.

  According to the third embodiment, it is possible to avoid interference with the cylinder head 30C and the cylinder block 29 of the valve housing 115, and the rotary valve 71 is separated from the combustion chamber 34 (see the first embodiment) and the above described. It is possible to prevent the rotary valve 71 from becoming high temperature.

  FIG. 13 shows a fourth embodiment of the present invention, which is a cross-sectional view corresponding to FIG. 3, and the parts corresponding to the first embodiment are only shown with the same reference numerals. Detailed description is omitted.

  The cylinder head 30D of the engine body 24D is provided with a single exhaust port 116 that communicates in common with the exhaust valve ports 37 (see the first embodiment). A cylinder is formed by forming a part of the exhaust port 116. An exhaust side connecting pipe portion 117 protruding forward from the front side surface of the head 30D is provided integrally with the cylinder head 30D. An exhaust pipe 119 is connected to the exhaust side connecting pipe portion 117 so as to form an exhaust passage 118 including the exhaust port 116 and to let the exhaust port 116 pass through an upstream end. Thus, a part of the cylinder head 30D integrally having the exhaust side connecting pipe portion 117 and the exhaust pipe 119 constitute exhaust passage forming means 120 that cooperates to form the exhaust passage 118.

  The exhaust side connecting pipe part 117 has a straight part 116aa in part, but is integrally connected to the cylinder head 30D so that a part of the exhaust port 116 forms a bent part 116a as a whole. The bent portion 116a is bent in the horizontal direction so as to protrude in the left direction in this embodiment in the left-right direction of the motorcycle when the engine body 24D is mounted on the vehicle body frame F. The exhaust side connecting pipe portion 117 is formed so as to be bent to the right side and is integrally connected to the cylinder head 30D.

  A curved cross-sectional area of the curved portion 116a formed by a curved portion disposed at a position closest to the exhaust valve port 37 in the exhaust passage 118, that is, a portion of the exhaust port 116, is a rotary valve 71 which is an exhaust control valve. The rotary valve 71 is disposed on the straight portion 116aa of the bent portion 116a.

  The rotary valve 71 is configured to change a partial passage cross-sectional area inside the bent portion 116 by projecting a part from the inner wall of the exhaust port 116 in the exhaust passage 118 into the exhaust port 116 when the rotary valve 71 is closed. The cylinder head 30D is disposed on the exhaust side connecting pipe portion 117 and is offset from the center CL of the bent portion 116a toward the inside of the curve, in this embodiment, from the center CL of the exhaust port 116 to the cam chain. A rotary valve 71 having a rotation axis CR oriented in the vertical direction at a position offset to the opposite side of the chamber 57 is disposed in the exhaust side connecting pipe portion 117.

  The rotary valve 71 is accommodated in a valve housing 74 that is provided integrally with an exhaust-side connecting pipe portion 117 that is integral with the cylinder head 30D. The valve housing 74 is configured to extend toward the cam chain chamber 57 opposite to the first embodiment, but has basically the same structure as the valve housing 74 of the first embodiment. Therefore, the same reference numerals are assigned to the portions corresponding to the first embodiment, and the detailed description is omitted.

  According to the fourth embodiment, since the rotary valve 71 is disposed in the exhaust port 116, the passage sectional area of the exhaust port 116 does not decrease when the rotary valve 71 is fully opened, and a relatively large rotary valve 71 is provided. The rotary valve 71 is disposed in the exhaust side connection pipe portion 117 at a position offset from the center CL of the exhaust port 116 to the opposite side of the cam chain chamber 57 even if it is disposed in the exhaust side connection pipe portion 117 of the cylinder head 30D. Therefore, it is easy to avoid the interference of the rotary valve 71 with the driven sprocket 55 provided on the camshaft 45 so as to constitute a part of the timing transmission mechanism 53, thereby reducing the size of the cylinder head 30D. Can be achieved.

  FIG. 14 is a longitudinal sectional view showing an essential part of an engine main body according to a fifth embodiment of the present invention. Between the cylinder block 121 and the cylinder head 30E constituting a part of the engine main body 24E, the cylinder bore of the cylinder block 121 is shown. A combustion chamber 126 that faces the top of the piston 125 slidably fitted to 124 is formed, and the cylinder head 30E has a pair of intake valve ports 127... Facing the combustion chamber 126 and a pair of exhaust valve ports. 128... Are provided. A pair of intake valves 129, which individually open and close the intake valve ports 127, and a pair of exhaust valves 130, which individually open and close the exhaust valve ports 128, are disposed in the cylinder head 30E so as to be opened and closed. The intake valves 129 are energized in the valve closing direction by the valve springs 131, respectively, and the exhaust valves 130 are energized in the valve closing direction by the valve springs 132, respectively.

  Between the cylinder head 30E and the head cover 123 coupled to the cylinder head 30E, a valve operating device 134 that opens and closes the intake valves 129 and the exhaust valves 130 is accommodated. The valve operating device 134 is disposed between the intake valves 129 and the exhaust valves 130 and is rotatably supported by the cylinder head 30E, and a pair of intake air provided on the cam shaft 135. A pair of intake side rocker arms 138 that opens and closes both intake valves 129 by swinging in accordance with the side cams 136, and a pair of exhaust side cams 137 that are provided on the camshaft 135 are rocked. And a pair of exhaust-side rocker arms 139 that open and close the exhaust valves 130 by moving them. The side rocker arms 138 and the exhaust side rocker arms 139 are supported by rocker shafts 140 and 141 parallel to the camshaft 135, respectively. The camshaft 135 includes a part of the timing transmission mechanism. The driven sprocket 170 is fixed.

  In such a SOHC type valve operating device 134, the angle β formed by the operation axes of the intake valves 129... And the exhaust valves 130. The cylinder head 30E can be downsized in the direction along the axis 124.

  The cylinder head 30E is provided with a single exhaust port 142 that communicates in common with both exhaust valve ports 128, and forms a part of the exhaust port 142 and projects forward from the front side surface of the cylinder head 30E. The exhaust side connecting pipe portion 147 is integrally provided in the cylinder head 30E. An exhaust pipe 144 that forms an exhaust passage 143 including the exhaust port 142 in cooperation with the exhaust side connection pipe 147 is connected to the exhaust side connection pipe 147 so that an upstream end of the exhaust pipe 144 communicates with the exhaust port 142. In addition, a part of the cylinder head 30E integrally having the exhaust side connecting pipe portion 147 and the exhaust pipe 144 constitute exhaust passage forming means 145 that cooperates to form the exhaust passage 143.

  The exhaust-side connecting pipe portion 147 is integrally connected to the cylinder head 30E so that a curved portion 142a is formed by a part of the exhaust port 142, and the curved portion 142a is a body frame of the engine body. In the mounted state, it bulges upward and curves upward, and the exhaust-side connecting pipe portion 147 is formed to bend downward and integrally connected to the cylinder head 30E.

  In the exhaust passage 143, the curved portion disposed at the position closest to the exhaust valve port 128, that is, the partial passage cross-sectional area inside the curved portion at the curved portion 142a of the exhaust port 142 is changed by the rotary valve 71 which is an exhaust control valve. To be sedated.

  The rotary valve 71 changes a partial passage cross-sectional area inside the curved portion 142a by projecting a part from the inner wall of the exhaust port 142 in the exhaust passage 143 into the exhaust port 142 when the rotary valve 71 is closed. The cylinder head 30E is disposed on the exhaust side connecting pipe portion 147 and has a rotation axis CR oriented in the left-right direction of the motorcycle at a position offset from the center CL of the bent portion 142a. Arranged in the exhaust side connecting pipe portion 147. Thus, the rotary valve 71 is accommodated in a valve housing 146 provided integrally with the exhaust side connecting pipe portion 147 that is integral with the cylinder head 30E.

  According to the fifth embodiment, the engine body 24E can be downsized in the direction along the axis of the cylinder bore 124. Further, the valve operating device 134 is configured as an SOHC type that does not have a dedicated driven sprocket for the exhaust valve 130..., And the driven sprocket 170 is attached to the camshaft 135 disposed between the intake valves 129 and the exhaust valves 130. Therefore, even if the valve housing 146 is provided integrally with the cylinder head 30E, the cylinder head 30E can be reduced in size and interference with the driven sprocket 170 of the rotary valve 71 can be avoided. .

  When a DOHC type valve is configured, a driven sprocket is provided on the exhaust camshaft, but a rotary valve is disposed inside the exhaust passage forming means that forms an exhaust passage bent in the vertical direction. By doing so, interference between the rotary valve and the driven sprocket can be avoided.

  In the first to fifth embodiments, the portion of the outer surface of the portion of the rotary valve 71 that protrudes into the intake passage that faces the upstream side in the intake passage is gently connected to the inner wall of the intake passage. However, it is also possible to smoothly connect the inner wall of the intake passage by appropriately selecting the setting position of the rotation axis CR of the rotary valve 71, so that the rotary valve 71 in the closed state can be connected. Generation of turbulence can be effectively suppressed by allowing the exhaust gas to flow smoothly on the surface.

  15 and 16 show a sixth embodiment. FIG. 15 is a sectional view of the rotary valve corresponding to FIG. 5, and FIG. 16 is a sectional view taken along line 16-16 of FIG.

  The rotary valve 148 protrudes partially into the exhaust port 150 from the inner wall of the bent portion 150a of the exhaust port 150 in the exhaust passage 149 formed by the exhaust passage forming means 154 when the valve is closed. A partial passage cross-sectional area on the inner side of the curve is changed, and is disposed in the exhaust side connecting pipe portion 151 that forms a part of the exhaust port 150 and constitutes a part of the exhaust passage forming means 154. And arranged in the exhaust side connecting pipe portion 151 so as to have a rotation axis CR at a position offset inward from the center CL of the bent portion 150a.

  The rotary valve 148 includes a valve main body 152 having a cylindrical outer surface centered on the rotation axis CR, and a passage portion 153 that constitutes a part of the exhaust port 150 when the rotary valve 148 is fully opened. Rotating shaft portions 152a and 152b that are coaxial with the rotation axis CR are coaxially and integrally provided at both ends of the valve main body 152. .

  In addition, at least a portion of the exhaust passage 149 where the rotary valve 148 is disposed, that is, a cross-sectional shape of the bent portion 150a of the exhaust port 150 is formed in an elliptical shape, and the passage portion 153 of the rotary valve 148 is fully opened. Sometimes, the exhaust port 150 is formed to be flush with a part of the inner wall of the exhaust port 150 in the circumferential direction.

  According to such a rotary valve 148, while maintaining the cross-sectional area of the exhaust port 150 in the exhaust passage 149 and the cross-sectional area shielded by the rotary valve 148, the remainder other than the portion where the passage portion 153 is formed in the valve main body 152. This portion can be enlarged to increase the strength of the rotary valve 148.

  FIG. 17 is a cross-sectional view corresponding to FIG. 15 of the rotary valve of the seventh embodiment.

  The rotary valve 157 protrudes from the inner wall of the bent portion 160a of the exhaust port 160 in the exhaust passage 159 formed by the exhaust passage forming means 158 when the rotary valve 157 is closed, thereby causing the bent portion 160a to protrude. A partial passage cross-sectional area inside the curve is changed, and is disposed in an exhaust side connecting pipe portion 161 that forms a part of the exhaust port 160 and constitutes a part of the exhaust passage forming means 158. And arranged in the exhaust side connecting pipe portion 161 so as to have a rotation axis CR at a position offset inward from the center CL of the bent portion 160a.

  In addition, the rotary valve 148 is coupled to and coupled to the inner rotor 162 so as to be operated behind the inner rotor 162 and the inner rotor 162 rotatably supported by the exhaust side connecting pipe portion 161. The outer rotor 163 is rotatably supported by the outer rotor 163.

  The inner rotor 162 includes a valve main body 164 having a cylindrical outer surface shape centered on the rotation axis CR, and a passage portion 165 constituting a part of the exhaust port 160 in the exhaust passage 159 when fully opened. The outer rotor 163 is formed to have an arcuate cross-sectional shape that surrounds the substantially half circumference of the inner rotor 162.

  In order to interlock and connect the inner rotor 162 and the outer rotor 163, for example, a protrusion 166 is provided on the outer periphery of the inner rotor 162 opposite to the passage 165 of the valve main body 164. On the other hand, a concave portion 167 into which the protrusion 166 is slidably fitted is provided on the inner periphery of the outer rotor 163 so as to extend long along the circumferential direction of the inner rotor 162.

  Thus, when the rotary valve 148 is fully opened, as shown in FIG. 17A, the inner rotor 162 is in a position where the passage portion 165 is flush with the inner surface of the exhaust port 160, and the protrusion 166 is The outer rotor 163 does not protrude into the exhaust port 160 because it is in contact with one end in the circumferential direction of the recess 167. When the rotary valve 148 is closed, first, the inner rotor 162 rotates around the rotation axis CR so that a part of the inner rotor 162 protrudes into the exhaust port 160. As shown in FIG. The outer rotor 163 does not protrude into the exhaust port 160 until the protrusion 166 contacts the other circumferential end of the recess 167. Further, when the inner rotor 162 further rotates in the valve closing direction from the state of FIG. 17B, the protrusion 166 is in contact with the other circumferential end of the recess 167, so that the outer rotor 162 is pushed by the protrusion 166. The rotor 163 rotates so as to protrude into the exhaust port 160, and the closed area of the exhaust port 160 becomes larger than when the inner rotor 162 is fully closed.

  According to the rotary valve 157 of the seventh embodiment as described above, the passage portion 165 of the inner rotor 162 is relatively made to bear a part of the area of the passage portion necessary for the entire rotary valve 157 by the inner rotor 162. It is possible to increase the strength of the rotary valve 157 by reducing the size and increasing the strength of the inner rotor 162 and reinforcing the outer rotor 163 with the inner rotor 162.

  FIG. 18 is a sectional view corresponding to FIG. 15 of the rotary valve of the eighth embodiment.

  A plurality of, for example, a pair of rotary valves 172 and 172 having a rotation axis CR at a position offset from the center CL of the exhaust passage 170 are coupled to and connected to the exhaust passage forming means 171 that forms the exhaust passage 170. The rotary valves 172... Have a rotation axis CR at a position offset from the center CL of the exhaust passage 170, as in the rotary valve 71 of the first embodiment. A valve main body 173 having a cylindrical outer surface shape centering on CR, and a passage portion 174 forming a part of the exhaust passage 170 when fully opened as shown in FIG. 18A are a part of the valve main body 173. When the valve is closed as shown in FIG. 18B, a part of the exhaust passage 170 protrudes from the inner wall of the exhaust passage 170 to the exhaust passage. It is intended to change the part cross-sectional area of 170.

  Moreover, the rotary valves 172... Are arranged at the same position in the flow direction of the exhaust passage 170. For example, gears 175 and 175 provided coaxially with the rotary valves 172. The

  According to the eighth embodiment, the rotary valves 172 are closed while the cross-sectional areas of the passage portions 174 are set small to increase the strength of the rotary valves 172. The change speed of the cross-sectional area of the exhaust passage 170 can be increased to improve the response.

  As a ninth embodiment of the present invention, as shown in FIG. 19, a pair of rotary valves 172 and 172 may be arranged in a staggered manner so as to be separated along the flow direction of the exhaust passage 170. Also in the ninth embodiment, a part of the exhaust passage 170 is constituted by the passage portions 174... Of both rotary valves 172... When fully opened as shown in FIG. When the valve is shown, a part of the rotary valves 172... Protrudes from the inner wall of the exhaust passage 170 into the exhaust passage 170.

  FIG. 20 shows a tenth embodiment of the present invention. An exhaust passage forming means 179 that forms the exhaust passage 178 is provided with a rotary valve 180 having a rotation axis CR at the center CL of the exhaust passage 178. The The rotary valve 180 includes a valve main body 181 configured in a cylindrical shape having a rotation axis CR at the center CL of the exhaust passage 178 and having an outer diameter larger than the inner diameter D1 of the exhaust passage 178. A passage hole 182 extending along one diameter line of 181 is formed so as to form shielding portions 183 and 183 on both sides thereof. The inner diameter of the passage hole 182 is exhausted when the rotary valve 180 is fully opened. In order to be flush with the inner surface of the passage 178, the inner diameter D1 of the exhaust passage 178 is set to be the same.

  Thus, when the rotary valve 180 is fully opened, as shown in FIG. 20A, the shields 183 and 183 are disposed in the exhaust passage 178 so that the passage hole 181 forms a part of the exhaust passage 178. As shown in FIG. 20B, when the valve is closed, both the shielding portions 183 and 183 protrude inward from the inner surface of the exhaust passage 178 at the same time. Become.

  According to the tenth embodiment, when the rotary valve 180 is closed, the shielding portions 183 on both sides of the passage hole 182 of the rotary valve 180 project simultaneously from the inner wall of the exhaust passage 178 into the exhaust passage 178. The speed of changing the cross-sectional area of the exhaust passage 178 by closing the valve 180 can be increased to enhance the responsiveness.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

1 is a right side view of a main part of a motorcycle according to a first embodiment. FIG. 4 is a longitudinal left side view of the 4-cycle engine, and is a longitudinal side view taken along line 2-2 in FIG. 3. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is sectional drawing which shows the state at the time of full opening (a) and a full closure (b) of a rotary valve along the 5-5 line | wire of FIG. It is a block diagram which shows the control system of a rotary valve. It is a figure which shows the output change accompanying the opening degree change of a rotary valve. FIG. 4 is a longitudinal left side view of a four-cycle engine corresponding to FIG. 2, showing a second embodiment. It is a 9-9 line expanded sectional view of FIG. It is a principal part enlarged view of FIG. 8 for demonstrating the state at the time of a fully open (a) and fully closed (b) of a rotary valve. It is the front view which simplified the cylinder head and cylinder block of 3rd Example. 12 is a cross-sectional view taken along line 12-12 of FIG. It is sectional drawing corresponding to FIG. 3 of 4th Example. It is a longitudinal cross-sectional view which shows the principal part of the engine main body of 5th Example. It is sectional drawing corresponding to FIG. 5 of the rotary valve of 6th Example. FIG. 16 is a cross-sectional view taken along line 16-16 in FIG. 15. It is sectional drawing corresponding to FIG. 15 of the rotary valve of 7th Example. It is sectional drawing corresponding to FIG. 15 of the rotary valve of 8th Example. It is sectional drawing corresponding to FIG. 15 of the rotary valve of 9th Example. It is sectional drawing corresponding to FIG. 15 of the rotary valve of 10th Example.

Explanation of symbols

30A, 30B, 30C, 30D, 30E ... cylinder heads 34, 126 ... combustion chambers 37, 128 ... exhaust valve ports 39, 130 ... exhaust valves 67, 103, 112, 118, 143, 149 , 159, 170, 178 ... exhaust passages 70, 105, 114, 120, 145, 154, 158, 171, 179 ... exhaust passage forming means 71, 148, 157, 172, 180 ... exhaust control valves Rotary valves 72, 152, 181 ... valve main bodies 73, 153 ... passage portion 162 ... inner rotor 163 ... outer rotor 182 ... passage hole 183 ... shielding portion CL ... Center CR of exhaust passage ... Rotation axis of rotary valve

Claims (6)

  Exhaust valves (39, 130) capable of opening and closing exhaust valve ports (37, 128) provided in the cylinder heads (30A, 30B, 30C, 30D, 30E) facing the combustion chambers (34, 126) are the cylinder heads. (30A-30E) is disposed so as to be openable and closable, and forms an exhaust passage (67, 103, 112, 118, 143, 149, 159, 170, 178) that communicates with the exhaust valve port (37, 128). The opening area of the exhaust passage (67, 103, 112, 118, 143, 149, 159, 170, 178) is added to the passage forming means (70, 105, 114, 120, 145, 154, 158, 171, 179). In an exhaust control device for an engine provided with an exhaust control valve (71, 148, 157, 172, 180) that can be changed, the exhaust control valve (71, 1) 8, 157, 172, 180) are exhausted from the inner wall of the exhaust passage (67, 103, 112, 118, 143, 149, 159, 170, 178) when the valve is closed. , 149, 159, 170, 178), and a part of the rotary valve projects into the exhaust passage (67, 103, 112, 118, 143, 149, 159, 170, 178) at least the outer surface of the outer surface facing the upstream side and projecting from the inner wall of the outer surface faces the upstream side, and the amount of projection from the inner wall is determined by the exhaust passage (67, 103, 112, 118, 143, 149, 159, 170), an exhaust control device for an engine, which is formed so as to gradually increase from the upstream side toward the downstream side.   The rotary valve (71, 148) has a rotation axis (CR) at a position offset from the center (CL) of the exhaust passage (67, 103, 112, 118, 143, 149) and the rotation axis ( A passage main part (73) constituting a part of the exhaust passage (67, 103, 112, 118, 143, 149) in a valve main body (72, 152) having a cylindrical outer surface shape centering on CR) when fully opened. 153) is formed so as to cut out a part of the valve main body (72, 152).   Of the exhaust passage (149), at least a portion where the rotary valve (152) is disposed is formed to have an elliptical cross-sectional shape, and the passage portion (153) is formed in the exhaust passage (149) when fully opened. The engine exhaust control device according to claim 2, wherein the valve main body (152) is formed so as to be flush with a part of a circumferential direction of an inner wall of the valve main body (152).   The rotary valve (157) has a rotational axis (CR) at a position offset from the center (CL) of the exhaust passage (159) and is rotatably supported by the exhaust passage formation means (158). An inner rotor (162) and an outer rotor (163) linked to and coupled to the inner rotor (162) so as to operate behind the inner rotor (162) and rotatably supported by the inner rotor (162) The exhaust control device for an engine according to claim 1, comprising:   A plurality of rotary valves (172, 172) having a rotation axis (CR) at a position offset from the center (CL) of the exhaust passage (170) are linked to each other and connected to the exhaust passage forming means (171). The engine exhaust control device according to claim 1, wherein the engine exhaust control device is disposed.   The rotary valve (180) has a rotation axis (CR) at the center (CL) of the exhaust passage (178) and is configured as a column having a larger diameter than the inner diameter of the exhaust passage (178). A passage hole (182) extending along one diameter line of the valve main body (181) is formed in the main body (181) so as to form shielding portions (183) on both sides thereof, and the passage hole ( 2. The engine exhaust control device according to claim 1, wherein an inner diameter of the second valve is set to be flush with an inner surface of the exhaust passage when the rotary valve is fully opened.

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