JP2009185639A - Variable valve gear of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear of an engine which allows a camshaft to become compact, reduction in torque required for an actuator and the fine adjustment of a lift amount. <P>SOLUTION: A camshaft 58 including a valve system cam 57 forcing a valve driving member 63 interlocked with an engine valve and making a coupled valve driving member 63 to abut thereon includes a recess 74 opening to the outside so as to notch a part of the valve system cam 57. A separate cam 59 formed separately from the valve system cam 57 by making a cam profile different from that of the valve system cam 57 is accommodated in the recess 74 by allowing the movement in the axial direction of the camshaft 58 between positions that forces abutment to a valve driving member 63 and avoids the abutment thereto. An actuator 80 for exerting power axially driving the rod 76 is interlocked with and coupled to a rod 76 fixed to the separate cam 59, and fitted in the camshaft 58 so as to be coaxial and axially movable. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus for an engine that can change an operation mode of an engine valve in accordance with an operation of an actuator.

During the compression stroke after the intake valve is closed, the exhaust valve is temporarily opened, and the mixture is effectively activated by the exhaust gas to stabilize combustion in the partial load operation region (for example, patents) There is literature 1). In addition, a valve cam in which two cam portions having different cam profiles are adjacent to each other in the axial direction of the camshaft has a position where one cam portion abuts the valve drive member, and the other cam portion serves as a valve drive member. A variable valve apparatus that is driven in the axial direction between the contact position and the contact position is already known, for example, in Patent Document 2.
JP 2006-233961 A Japanese Patent Laid-Open No. 61-212615

  However, the one disclosed in Patent Document 1 is configured to temporarily lift the exhaust valve by directly pushing the rocker arm with an actuator, so that the lift amount of the exhaust valve is gradually increased as the valve is opened. It was difficult to finely adjust the lift amount such as Further, in the variable valve operating device disclosed in Patent Document 2, the valve cam itself, which is relatively heavy, is moved relatively large in the axial direction of the camshaft. High torque is required. Moreover, since the width of the valve cam in the axial direction of the camshaft increases, the camshaft axial length increases.

  The present invention has been made in view of such circumstances, and enables the reduction of torque required for the actuator and the fine adjustment of the lift amount while enabling the camshaft to be made compact. An object of the present invention is to provide a variable valve operating device for an engine.

  In order to achieve the above object, a first aspect of the present invention is a variable valve operating apparatus for an engine in which the operation mode of the engine valve can be changed in accordance with the operation of the actuator. A camshaft provided with a valve cam for contacting a valve drive member linked to and connected to the engine valve to the cylinder head is rotatably supported, and a part of the valve cam is notched outward. A position where a separate cam formed on the camshaft and having a cam profile different from that of the valve cam and formed separately from the valve cam contacts the valve drive member. And the position where the contact with the valve drive member is avoided, the camshaft can be moved in the axial direction, is accommodated in the recess, is fixed to the separate cam and is The rod is engaged axially movably fitted coaxially and in Mushafuto, wherein the actuator to exert a force for driving the rod in the axial direction is interlocked, is connected.

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the separate cam overlaps a part of a base circle portion of the valve cam as viewed from the axial direction of the camshaft. And a base circle portion formed in an arc shape centering on the axis of the camshaft, and projecting outward from the base circle portion and smoothly connecting both ends in the circumferential direction to the base circle portion. And a high-order portion.

  According to a third aspect of the invention, in addition to the configuration of the first or second aspect of the invention, the actuator has an operating axis parallel to the cylinder axis and a part of the actuator as viewed from the axial direction of the camshaft. It is attached to the side wall of the cylinder head so as to overlap the block.

  In addition to the configuration of any of the first to third aspects of the present invention, the engine body is supported on a vehicle body frame so as to be able to swing, and any one of the camshafts in the axial direction is provided. The engine body and the vehicle body frame are connected to each other via a link mechanism on one side, and the actuator is attached to a side wall of the cylinder head on the side where the link mechanism is disposed.

  The exhaust valve 45 of the embodiment corresponds to the engine valve of the present invention, the exhaust valve cam 57 of the embodiment corresponds to the valve cam of the present invention, and the exhaust side rocker arm 63 of the embodiment is the valve drive of the present invention. Corresponding to the member, the solenoid 80 of the embodiment corresponds to the actuator of the present invention.

  According to the first aspect of the invention, the operation mode of the engine valve can be changed between a state in which the valve drive member is brought into contact with the valve cam and a state in which the valve drive member is brought into contact with a separate cam, It is possible to change the operation mode of the engine valve by driving a separate cam, which is a separate body from the valve cam, in the axial direction of the camshaft. In addition, since the actuator only needs to demonstrate the power to drive the separate cam, the load required for the actuator can be reduced compared to the conventional one that has driven the entire valve cam. Since a part of the valve cam is cut out and accommodated in a recess formed in the camshaft, it is not necessary to set a large width of the valve cam in order to change the operation mode of the engine valve. The camshaft can be made compact by shortening the length. Moreover, when operating the valve drive member with a separate cam, the engine valve lifts in response to the cam profile of the separate cam, so the engine valve can be opened smoothly by setting the cam profile of the separate cam as appropriate. It is also easy to gradually increase the lift amount so that it can be reduced.

  According to the second aspect of the present invention, since both ends in the circumferential direction of the high-order portion of the separate cam are smoothly connected to the base circle portion, the opening / closing operation of the engine valve in a state where the valve drive member is in contact with the separate cam is performed. As a smooth one, it is possible to reduce the operating noise generated when the valve is opened.

  According to the invention described in claim 3, by making the operating axis of the actuator parallel to the cylinder axis, the width of the entire engine body in the direction along the axis of the camshaft can be suppressed, and a part of the actuator is cam Since it overlaps with the cylinder block when viewed from the axial direction of the shaft, it is possible to concentrate the mass of the engine body by arranging the actuator at a position closer to the center of gravity of the engine body.

  According to the fourth aspect of the present invention, the vibration applied to the actuator can be suppressed by arranging the actuator at a position close to the link mechanism.

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

  1 to 8 show an embodiment of the present invention. FIG. 1 is a left side view of a scooter type motorcycle, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. 3-3 is a sectional view taken along line 3-3, FIG. 4 is a view showing valve lifts of intake and exhaust valves, FIG. 5 is a partially cutaway side view as seen from the direction of arrow 5 in FIG. 2, and FIG. FIG. 7 is a sectional view taken along line -6, FIG. 7 is a sectional view taken along line 7-7 in FIG. 6, and FIG.

  First, in FIG. 1, a body frame 15 of a scooter type motorcycle includes a front fork 16 that pivotally supports a front wheel WF and a head pipe 18 that supports a steering handle 17 connected to the front fork 16 so as to be steerable. The down tube 19 extending rearwardly downward from the head pipe 18, a pair of left and right lower frame pipes 20... Which are fixed to the lower sides of the down tube 19 and extending rearward, and a rear end of the lower frame pipe 20. A pair of left and right rear frame pipes 21 are provided. The rear frame pipe 21 extends rearward from the rear end of the lower frame pipe 20 and extends rearward from the rear end of the inclined frame portion 21a. The rear frame pipes 21... Are connected to each other. It is.

  A bracket 22 is provided at an integrally connected portion of both the lower frame pipes 20 and the rear frame pipes 21 in the vehicle body frame 15, and the power unit P swings up and down via the link mechanism 23 in the bracket 22. The rear wheel WR arranged on the right side of the rear portion of the power unit P is pivotally supported on the rear portion of the power unit P. A rear cushion unit 24 is provided between the rear part of the left rear frame pipe 21 and the rear part of the power unit P among the rear frame pipes 21.

  A fuel tank 25 supported by the lower frame pipes 20 is disposed between the lower frame pipes 20 in front of the power unit P, and two helmets can be accommodated above the power unit P, for example. A storage box 26 formed on the rear frame pipe 21 is supported by the rear frame pipe 21.

  The vehicle body frame 15 is covered with a vehicle body cover 27 made of synthetic resin. The vehicle body cover 27 is provided under the leg shield 28 for covering the front of the driver's feet and the leg shield 28 for placing the rider's feet. A tandem type that includes a step floor 29 that continuously covers the fuel tank 25 and a side cover 30 that continues to the step floor 29 and covers the rear portion of the vehicle body from both sides. The storage box 26 can be opened and closed on the side cover 30 from above. Is provided.

  The power unit P includes a single-cylinder four-cycle engine E disposed in front of the rear wheel WR and a continuously variable transmission M provided between the engine E and the rear wheel WR.

  2 and 3 together, the engine body 34 of the engine E includes a crankcase 35 that rotatably supports a crankshaft 33 (see FIG. 1) having a rotation axis parallel to the rotation axis of the rear wheel WR. (Refer to FIG. 1), a cylinder block 36 having a cylinder bore 39 into which a piston 40 connected to the crankshaft 33 is slidably fitted, and a combustion chamber 41 facing the top of the piston 40 are provided in the cylinder block 36. And a head cover 38 that is coupled to the cylinder head 37 on the opposite side of the cylinder block 36. The axis of the cylinder bore 39, that is, the cylinder axis C is substantially the same. It is arranged with a slight forward tilt until it becomes horizontal. Further, the link mechanism 23 is provided between the front left side of the crankcase 35 in the engine body 34 and the bracket 22 of the body frame 15.

  As shown in FIG. 1, the crankcase 35 is provided with a transmission case 32 that houses the continuously variable transmission M and extends to the left side of the rear wheel WR. A rear wheel WR is pivotally supported at the rear portion, and a lower end portion of the rear cushion unit 24 is connected to a rear portion of the transmission case 32.

  An intake port 42 that can communicate with the combustion chamber 41 is provided on the upper side surface of the cylinder head 37, and an exhaust port 43 that can communicate with the combustion chamber 41 is provided on the lower side surface of the cylinder head 37. An intake valve 44 that opens and closes the intake port 42 and an exhaust valve 45 that serves as an engine valve that opens and closes the exhaust port 43 are arranged in a substantially V shape on a projection onto a plane orthogonal to the rotational axis of the crankshaft 33. It is disposed on the cylinder head 37 and is spring-biased in the direction of closing the intake port 42 and the exhaust port 43. A spark plug 46 facing the combustion chamber 41 is attached to the right side surface of the cylinder head 37 with the motorcycle facing forward in the direction of travel.

  An intake pipe 48 that forms an intake passage 47 that communicates with the intake port 42 is connected to the upper side surface of the cylinder head 37, and the intake pipe 48 is bent in an arc shape toward the rear side of the motorcycle. It is formed. The upstream end of the intake pipe 48 is connected to the downstream end of the throttle body 49 (see FIG. 1). 1). Further, a fuel injection valve 51 for injecting fuel toward the intake port 42 is attached to the intake pipe 48.

  An exhaust pipe 52 (see FIG. 1) leading to the exhaust port 43 is connected to the lower side surface of the cylinder head 37, and the downstream end of the exhaust pipe 52 is an exhaust muffler 53 (located on the right side of the rear wheel WR). 1).

  A variable valve device 55 that opens and closes the intake valve 44 and the exhaust valve 45 is accommodated between the cylinder head 37 and the head cover 38. The variable valve device 55 has an axis parallel to the axis of the crankshaft 33. And the camshaft 58 on which the intake valve cam 56 and the exhaust valve cam 57 are provided, and the exhaust valve cam 57 have different cam profiles. A separate cam 59 that is movable in the axial direction of the camshaft 58, an intake side and exhaust side rocker shafts 60, 61 that have an axis parallel to the camshaft 58 and are supported by the cylinder head 37, and the intake An intake side rocker arm 62 that is swingably supported on the intake side rocker shaft 60 so as to drive the intake valve 44 by following the valve operating cam 56; And an exhaust-side rocker arm 63 which is swingably supported on the exhaust side rocker shaft 61 as being driven by the said exhaust valve operating cam 57 or the separate body cam 59 for opening and closing the exhaust valve 45.

  The camshaft 58 includes a driven sprocket 64 fixed to the left end portion of the camshaft 58 in a state of facing forward in the traveling direction of the motorcycle, and a cam chain 65 wound around the driven sprocket 64. The rotational power of the crankshaft 33 is transmitted by a transmission mechanism 66 at a reduction ratio of 1/2, and the cam chain 65 is a chain travel passage 67 formed across the cylinder block 36, the cylinder head 37, and the head cover 38. It is housed inside so as to be able to run.

  The intake valve cam 56 and the exhaust valve cam 57 project from the arcuate base circles 56a and 57a centering on the axis of the camshaft 58 and outward from the base circles 56a and 57a. As described above, the base circle portions 56a and 57a have high-order portions 56b and 57b that connect both ends in the circumferential direction, and are provided integrally with the camshaft 58 with the phases of the high-order portions 56b and 57b shifted.

  A roller 70 that is in rolling contact with the intake valve cam 56 is pivotally supported at one end portion of the intake side rocker arm 62 supported so as to be swingable by the intake side rocker shaft 60, and is connected to the other end portion of the intake side rocker arm 62. The tappet screw 71 that contacts the intake valve 44 is screwed so that the advance / retreat position can be adjusted. In addition, a roller 72 that is in rolling contact with the exhaust valve cam 57 and is also capable of rolling with the separate cam 59 is attached to one end portion of the exhaust rocker arm 63 that is swingably supported by the exhaust rocker shaft 61. A tappet screw 73 that is pivotally supported and abuts against the exhaust valve 45 is screwed to the other end of the exhaust side rocker arm rocker arm 63 so that the forward / backward position can be adjusted.

  The separate cam 59 is accommodated in a recess 74 provided in the camshaft 58 so as to open outward, and the recess 74 cuts a part of the exhaust valve cam 57. The camshaft 58 is provided between the exhaust valve cam 57 and the intake valve cam 56. In this embodiment, the concave portion 74 is directed substantially opposite to the high position portion 57b of the exhaust valve cam 57. It is formed to open.

  The separate cam 59 is located in the vicinity of the exhaust valve cam 57 in a rolling contact with the roller 72 of the exhaust rocker arm 64, and is separated from the exhaust valve cam 57 and the roller of the exhaust rocker arm 64. The camshaft 58 is accommodated in the recess 74 so that the camshaft 58 cannot be rotated around the axis while the camshaft 58 can move in the axial direction between the position where 72 avoids rolling contact.

  The separate cam 59 has an arc-shaped base circle portion 59a centering on the axis of the camshaft 58 and a high-order portion 59b protruding outward from the base circle portion 59a. The circular portion 59 a is formed so as to overlap a part of the base circular portion 57 a of the exhaust valve cam 57 as viewed from the axial direction of the cam shaft 58.

  Further, as shown in FIG. 4, the high-order part 59b slightly protrudes from the base circle part 59a at a phase corresponding to the valve closing end of the high-order part 56b in the intake valve cam 56. Both ends in the circumferential direction are connected to the base circle 59a so as to draw a smooth curve. Thus, when the separate cam 59 is moved to a position where the roller 72 of the exhaust side rocker arm 64 is brought into rolling contact with the exhaust side rocker arm 64, the exhaust side rocker arm 64 opens the exhaust valve 45 by the high position portion 57 b of the exhaust valve cam 57. The valve closing state is maintained by contacting the base circular portion 57a of the exhaust valve cam 57 after rotating in such a manner, but it is separated at the end of the closing operation after the intake valve 44 is opened. The exhaust-side rocker arm 64 is slightly rotated so that the exhaust valve 45 is slightly opened by the high position portion 59 b of the cam 59. As a result, as shown in FIG. 4, the exhaust valve 45 can be temporarily opened during the compression stroke, the combustion of the air-fuel mixture in the combustion chamber 41 is activated by the exhaust gas, the NOx emission amount is reduced, and the engine output It is possible to improve the fuel consumption and reduce fuel consumption. Further, if the valve opening timing is changed, a decompression state in which the exhaust valve 45 is opened slightly in order to reduce the compression pressure of the combustion chamber 41 at the time of starting the engine E or the like is set. It can also be obtained. On the other hand, when the valve body cam 59 is moved to a position where the exhaust side rocker arm 64 avoids contact with the roller 72, the exhaust side rocker arm 64 is rotationally driven only by the exhaust valve cam 57, and the exhaust valve 45 is exhausted. The opening / closing operation is performed in an operation mode corresponding to the cam profile of the valve cam 57. That is, the opening / closing operation mode of the exhaust valve 45 corresponding to the cam profile of the exhaust valve cam 57 and the timing when the valve valve is originally closed while the opening / closing operation corresponding to the cam profile of the exhaust valve cam 57 is temporarily closed. The operation mode of the exhaust valve 45 that is adapted to obtain the valve open state can be switched by the movement of the separate cam 59 along the axial direction of the cam shaft 58.

  The camshaft 58 and the driven sprocket 64 are provided with a coaxial through hole 75, and a rod 76 is fitted into the through hole 75 so as to be axially movable so that one end thereof protrudes from the driven sprocket 64. The separate cam 59 is fixed to the rod 76. In addition, a cap 77 that closes the through hole 75 is fixed to the camshaft 58 at the end opposite to the driven sprocket 64 by, for example, screwing, and a coil is interposed between the cap 77 and the rod 76. The spring 78 is contracted. The spring 78 urges the rod 76 toward the side where one end of the rod 76 protrudes from the driven sprocket 64 becomes larger, and the separate cam 59 separates from the exhaust valve cam 57. Thus, the spring 78 is biased by the spring 78 to a position where the roller 72 of the exhaust side rocker arm 64 avoids rolling contact.

  A solenoid 80 serving as an actuator that exerts power for driving the rod 76 in the axial direction is linked and connected to the rod 76 via a transmission means 79. The solenoid 80 has an output shaft 80a that operates in the axial direction, and is attached to the side wall of the cylinder head 37 in a posture in which the operation axis, that is, the axis of the output shaft 80a is parallel to the cylinder axis C, that is, the axis of the cylinder bore 40. .

  The solenoid 80 is supported by a pair of bolts 81 and 81 on the side wall of the cylinder head 37 on the same side as the link mechanism 23 that connects the engine body 34 and the vehicle body frame 15 on either one of the axial directions of the camshaft 58. Since the link mechanism 23 is provided between the front left side of the crankcase 35 in the engine main body 34 and the bracket 22 of the vehicle body frame 15 in this embodiment, the link mechanism 23 is supported by the member 82. Is attached to the lower part of the left side wall of the cylinder head 37, and the solenoid 80 is attached to the lower part of the left side wall of the cylinder head 37 via the support member 82. Moreover, the solenoid 80 supported by the support member 82 attached to the cylinder head 37 is disposed so that a part of the solenoid 80 overlaps the cylinder block 36 when viewed from the axial direction of the camshaft 58. As shown in FIG. 1, a solenoid 80 is disposed immediately above the engine swing shaft 95 in the link mechanism 23.

  Referring to FIGS. 5 to 8, the transmission means 79 includes a first lever 83 that abuts the tip of the rod 76 on one end of the rod 76, and a relative rotation of one end on the base end of the first lever 83. A connecting shaft 84 that is immovably connected, a second end 85 that is connected to the other end of the connecting shaft 84 so that the base end portion cannot be relatively rotated, and a second lever 85 that is adjustable in advancing / retreating position. A screw member 86 that contacts the output shaft 80a of the solenoid 80;

  The left side wall of the cylinder head 37 corresponding to one end of the rod 76 is integrally provided with a protruding portion 37a protruding outward, and the first lever 83 can be rotated on the protruding portion 37a. A recess 87 opened to the side of the chain travel passage 67 is formed so as to be accommodated in the shaft, and a support hole 88 through which one end of the connecting shaft 84 extending in the vertical direction is rotatably inserted is provided. One end portion of the connecting shaft 84 inserted through 88 is connected to the base end portion of the first lever 82 in the recess 87 so as not to be relatively rotatable. That is, one end of the connecting shaft 84 is formed in a non-circular shape with a flat surface 84a at a part of the outer periphery thereof, and the first lever has a non-circular shape corresponding to the cross-sectional shape of the one end of the connecting shaft 84. One end portion of the connecting shaft 84 is inserted into the pair of connecting holes 90, 90 formed in the base end portion of the 83 so that the one end portion of the connecting shaft 84 is connected to the first lever 83 so as not to be relatively rotatable. An annular seal member 89 is interposed between the inner periphery of the support hole 88 and the outer periphery of the connecting shaft 84.

  The support member 82 is formed so as to cover the connecting shaft 84 that protrudes outward from the raised portion 37a and extends downward from the outside. A cover portion 82a that covers the second lever 85 from below is integrally formed. Thus, the other end portion, that is, the lower end portion of the connecting shaft 84 is connected to the base end portion of the third lever 85 so as not to rotate relative to the upper portion of the cover portion 82a. A pair of connecting walls 85 a and 85 a that are opposed to each other with a space therebetween in the vertical direction are integrally provided at the base end portion of the third lever 85. The other end portion of the connecting shaft 84 has a flat surface 84b on a part of the outer periphery thereof and is formed in a non-circular shape, and has a non-circular shape corresponding to the cross-sectional shape of the other end portion of the connecting shaft 84. The other end portion of the connecting shaft 84 is inserted into the connecting holes 91 formed in the both connecting walls 85a, so that the other end portion of the connecting shaft 84 is connected to the second lever 85 so as not to be relatively rotatable.

  A nut 92 is fixed to the tip of the second lever 85, and the screw member 86 screwed to the nut 92 so as to adjust the advance / retreat position contacts the tip of the output shaft 80 a of the solenoid 80. A retaining nut 93 that contacts the nut 92 on the opposite side of the solenoid 80 is screwed into the screw member 86.

  According to such a transmission means 79, when the solenoid 80 is actuated to project the output shaft 80a, the connecting shaft 84 and the first lever 83 rotate in the clockwise direction of FIG. 2 via the second lever 85. Then, the rod 76 is pushed against the spring biasing force of the spring 78, and the separate cam 59 moves close to the exhaust valve cam 57 to a position where the roller 72 of the exhaust-side rocker arm 64 is brought into rolling contact. When the solenoid 80 is in an inoperative state, the separate cam 59 is moved away from the exhaust valve cam 57 by the spring force of the spring 78 and moved to a position where the rolling contact with the roller 72 of the exhaust rocker arm 64 is avoided. It will be.

  Next, the operation of this embodiment will be described. In the cylinder head 37, a camshaft 58 provided with an exhaust valve cam 57 for contacting an exhaust side rocker arm 63 linked to and connected to the exhaust valve 45 is rotatable. The camshaft 58 is provided with a recessed portion 74 that is supported by the camshaft 58 and is opened outwardly so as to cut out a part of the exhaust valve cam 57. The camshaft 58 has a cam profile that is different from that of the exhaust valve cam 57. A separate cam 59 formed separately from the valve cam 57 is located between the position where the exhaust rocker arm 63 abuts and the position where the exhaust rocker arm 63 avoids contact. The rod 7 is accommodated in the recess 74 so as to be movable in the axial direction, is fixed to the separate cam 59, and is coaxially fitted to the cam shaft 58 so as to be movable in the axial direction. The solenoid 80 to exert a force for driving the rod 76 in the axial direction is interlocked, they are connected.

  Therefore, the operation mode of the exhaust valve 45 changes between a state in which the exhaust side rocker arm 64 is in contact with the exhaust valve cam 57 and a state in which the exhaust side rocker arm 64 is in contact with the separate cam 59 and the exhaust valve cam 57. The operating mode of the exhaust valve 45 can be changed by driving a separate cam 59 that is a separate body from the exhaust valve cam 57 in the axial direction of the camshaft. In addition, since the solenoid 80 only needs to exhibit the power to drive the separate cam 59, the load required for the solenoid 80 can be reduced as compared with the conventional one that has driven the exhaust valve cam 57 as a whole. Further, the separate cam 59 is housed in a recess 74 formed in the camshaft 58 by cutting out a part of the exhaust valve cam 57, so that the exhaust valve 45 is changed in order to change the operation mode of the exhaust valve 45. It is not necessary to set the width of the cam 57 large, and the cam shaft 58 can be made compact by shortening the axial length of the cam shaft 58.

  Moreover, when the exhaust rocker arm 64 is operated by the separate cam 59, the exhaust valve 45 is lifted corresponding to the cam profile of the separate cam 59, so that the exhaust valve 45 can be set by appropriately setting the cam profile of the separate cam 59. It is also easy to gradually increase the lift amount so as to smoothly open the valve.

  Further, the exhaust valve cam 57 and the separate cam 59 protrude outwardly from the arcuate base circles 57a and 59a centering on the axis of the camshaft 58 and the base circles 57a and 59a. The base circle portion 59a of the separate cam 59 is part of the base circle portion 57a of the exhaust valve cam 57 when viewed from the axial direction of the cam shaft 58. Since both ends of the high position portion 59b of the separate cam 59 are smoothly connected to the base circular portion 59a of the separate cam 59, the exhaust in the state where the exhaust rocker arm 64 is in contact with the separate cam 59. By making the opening and closing operation of the valve 45 smooth, it is possible to reduce the operation noise generated when the valve is opened.

  Further, since the solenoid 80 is arranged with its operating axis parallel to the cylinder axis C, the width of the entire engine body 34 in the direction along the axis of the camshaft 58 can be suppressed. Since the shaft 58 is attached to the side wall of the cylinder head 37 so as to partially overlap the cylinder block 36 when viewed from the axial direction, the solenoid 80 is disposed at a position closer to the center of gravity of the engine body 34 and the mass of the engine body 34 is increased. Can be centralized.

  Further, since the solenoid 80 is attached to the side wall of the cylinder head 37 on the side where the link mechanism 23 provided between the vehicle body frame 15 and the engine body 34 is disposed, the solenoid 80 is disposed at a position close to the link mechanism 23. Thus, vibration applied to the solenoid 80 can be suppressed. In addition, since the solenoid 80 is disposed immediately above the engine swing shaft 95 in the link mechanism 23, vibration applied to the solenoid 80 can be more effectively suppressed.

  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.

It is a left view of a scooter type motorcycle. FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is a figure which shows the valve opening lift of an intake valve and an exhaust valve. FIG. 5 is a partially cutaway side view seen from the direction of arrow 5 in FIG. 2. FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. It is a disassembled perspective view which shows the structure of a transmission means.

Explanation of symbols

15 ... Body frame 23 ... Link mechanism 34 ... Engine body 36 ... Cylinder block 37 ... Cylinder head 45 ... Exhaust valve 55 as engine valve ... Variable valve operating device 57- ..Valve exhaust cams 57a, 59a, which are valve cams, base circular portions 57b, 59b, high position portion 58, cam shaft 59, separate cam 63, valve drive member Exhaust-side rocker arm 74 ... Recess 76 ... Rod 80 ... Solenoid C as actuator ... Cylinder axis

Claims (4)

  In a variable valve operating apparatus for an engine in which the operation mode of the engine valve (45) can be changed according to the operation of the actuator (80), a cylinder head (part of the engine body (34) together with the cylinder block (36)) 37), a camshaft (58) provided with a valve cam (57) for contacting a valve drive member (63) linked and connected to the engine valve (45) is rotatably supported. The camshaft (58) is provided with a recess (74) that opens outwardly so as to cut out a part of (57), and has a cam profile different from that of the valve cam (57). A position where a separate cam (59) formed separately from the cam (57) contacts the valve drive member (63) and a position where contact with the valve drive member (63) is avoided; Between the camshafts (5 ) Is accommodated in the recess (74), is fixed to the separate cam (59), and is coaxially fitted to the cam shaft (58) so as to be axially movable. A variable valve operating system for an engine, characterized in that an actuator (80) that exerts power for driving the rod (76) in the axial direction is interlocked and coupled to the rod (76).   The separate cam (59) overlaps a part of the base circle (57a) of the valve cam (57) when viewed from the axial direction of the camshaft (58). A base circle portion (59a) formed in an arc shape centered on the axis, and projects outwardly from the base circle portion (59a) and smoothly connects both circumferential ends to the base circle portion (59a). 2. The variable valve operating apparatus for an engine according to claim 1, wherein the variable valve operating apparatus is formed to have a leveled high-order part (59b).   The actuator (80) has its operating axis parallel to the cylinder axis (C) and partly overlaps the cylinder block (36) when viewed from the axial direction of the camshaft (58). 37) The variable valve operating apparatus for an engine according to claim 1 or 2, wherein the variable valve operating apparatus is attached to a side wall of 37).   The engine body (34) is swingably supported on a vehicle body frame (15) of a vehicle, and the space between the engine body (34) and the vehicle body frame (15) is on either side of the camshaft (58) in the axial direction. The first and second actuators are connected via a link mechanism (23), and the actuator (80) is attached to a side wall of the cylinder head (37) on the side where the link mechanism (23) is disposed. 4. The variable valve operating apparatus for an engine according to any one of 3 above.

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