TW201713846A - Engine - Google Patents

Abstract

A rocker shaft includes a shaft member and a collar member. The shaft member includes a first end and a second end. The first end is one end of the shaft member in a direction of an axis of the rocker shaft, and is supported by a first shaft support portion. The second end is the other end of the shaft member in the direction of the axis of the rocker shaft, and is supported by a second shaft support portion. The collar member is provided separately from the shaft member. The collar member is disposed between the first end and the second end in the direction of the axis of the rocker shaft. A first rocker arm and a second rocker arm are attached to the collar member. The collar member has an outer diameter larger than each of an outer diameter of the first end and an outer diameter of the second end. The shaft member is inserted into a hole provided in the collar member.

Description

Cross-seat vehicle engine

The present invention relates to an engine for a straddle type vehicle.

An engine with a variable valve mechanism exists in an engine for a straddle type vehicle. The variable valve mechanism includes a low speed rocker arm used in a low speed region of the engine rotational speed and a high speed rocker arm used in a high speed region of the engine rotational speed. For example, in Japanese Patent Laid-Open No. 2015-010552, the low speed rocker arm and the high speed rocker arm are mounted side by side on the rocking shaft in the axial direction of the rocking shaft. In the low speed region, the low speed rocker arm is driven by the low speed cam to open and close the valve. In the high speed region, the low speed rocker arm is coupled to the high speed rocker arm. Specifically, the coupling pin inserted into the hole of the low speed rocker arm is moved by the actuator and inserted into the hole of the high speed rocker arm. Thereby, the low speed rocker arm is coupled to the high speed rocker arm. In this state, the low speed rocker arm is not driven by the cam for low speed, and the high speed rocker arm is driven by the cam for high speed, thereby opening and closing the valve.

In the variable valve mechanism described above, if the connection rigidity of the rocking unit including the low speed rocker arm, the high speed rocker arm, and the rocking shaft is low, the stability of the movable valve mechanism is adversely affected. Therefore, research has been made to improve the rigidity of the joint. First, the inventors thought of increasing the diameter of the joint pin as a method of increasing the joint rigidity. However, if the diameter of the connecting pin is increased, the quality of the connecting pin is increased. Further, since the portion for inserting the connecting pin in the rocker arm is also increased, the mass of the rocker arm is also increased. Therefore, there is a problem that the behavior of the rocker arm is deteriorated due to an increase in the inertial mass of the entire rocking unit. In particular, the straddle type vehicle is used even in an area where the engine rotation speed is higher than that of the automobile, and thus the problem of the deterioration of the behavior is remarkable. Therefore, in order to suppress an increase in the inertial mass, the inventors conceived to increase the joint rigidity from the portion where the joint pin is closer to the center of rotation of the rocker arm, and it is thought to increase the diameter of the rocking shaft. According to this configuration, the cross-sectional coefficient of the rocking shaft can be increased while suppressing an increase in the inertial mass, and the connection rigidity of the rocking unit can be improved. However, if the diameter of the rocking shaft is increased, the hole provided in the shaft support portion of the cylinder head for supporting the rocking shaft is also increased. Therefore, the shaft support portion becomes thin and the rupture occurs. If the thickness of the shaft support portion is ensured in order to avoid cracking, there is a problem that the cylinder head is enlarged. The present invention improves the connection rigidity of the rocking unit, suppresses an increase in the inertial mass of the rocking unit, and breaks the shaft support portion, and suppresses the increase in the size of the cylinder head. The straddle-type vehicle engine according to the first aspect includes a cylinder head, a valve, a rocking unit, a camshaft, and an opening/closing point changing unit. The valve is mounted to the cylinder head. The shaking unit presses the valve to open and close the valve. The camshaft drives the rocking unit. When opening and closing, the point change unit changes the opening and closing timing of the valve. The rocking unit includes a rocking shaft, a first rocker arm, a second rocker arm, a pressing member, and a coupling pin. The rocking shaft is supported by the cylinder head. The first rocker arm includes a first mounting portion and a first contact portion. The first mounting portion is attached to the rocking shaft. The first contact portion is connected to the first mounting portion and is provided in contact with the cam shaft. The first rocker arm rotates about the axis of the rocking shaft by the first contact portion being in contact with the cam shaft. The second rocker arm includes a second mounting portion and a second contact portion. The second mounting portion is attached to the rocking shaft. The second contact portion is connected to the second mounting portion and is provided in contact with the cam shaft. The second rocker arm is arranged side by side with the first rocker arm in the axial direction of the rocking shaft. The second rocker arm rotates about the axis of the rocking shaft by the second contact portion being in contact with the cam shaft. The pressing member is rotated about the axis of the rocking shaft to press the valve. The connecting pin can be moved to the connecting position and the releasing position by the opening/closing point changing unit. The connecting pin connects the second rocker arm to the pressing member at the connecting position. The second rocker arm is released from the pressing member at the release position. The pressing member coupling pin presses the valve in accordance with the rotation of the first rocker arm at the release position, and the coupling pin presses the valve at the connection position as the second rocker arm rotates. The cylinder head includes a first shaft support portion and a second shaft support portion that support the rocking shaft. The rocking shaft includes a shaft member and a collar member. The shaft member includes a first end portion and a second end portion. The first end portion is one end portion in the axial direction of the rocking shaft, and the second end portion is the other end portion in the axial direction of the rocking shaft. The first end portion is supported by the first shaft support portion. The second end portion is supported by the second shaft support portion. The collar member and the shaft member are separate individuals. The collar member is disposed between the first end portion and the second end portion in the axial direction of the rocking shaft. The first rocker arm and the second rocker arm are attached to the collar member. The outer diameter of the collar member is larger than the outer diameter of the first end portion and larger than the outer diameter of the second end portion. The shaft member is inserted into the bore of the collar member. In the engine for a straddle type vehicle according to the aspect of the invention, the outer diameter of the collar member to which the first rocker arm and the second rocker arm are attached is larger than the outer diameter of the first end portion of the shaft member and larger than the second end portion of the shaft member. The outer diameter. Thereby, the connection rigidity of the rocking unit can be increased, and the increase in the inertial mass can be suppressed. Further, the outer diameter of the first end portion and the outer diameter of the second end portion are respectively smaller than the outer diameter of the collar member. Therefore, it is possible to suppress the expansion of the holes provided in the first shaft support portion and the second shaft support portion in order to support the rocking shaft. Therefore, it is possible to suppress the occurrence of cracking in the shaft support portion, and it is possible to suppress an increase in size of the cylinder head. Further, the collar member and the shaft member are independent individuals, and the shaft member is inserted into the bore of the collar member. Therefore, at the time of assembly, the first rocker arm and the second rocker arm can be temporarily assembled to the collar member, and the temporary assembly can be disposed between the first shaft support portion and the second shaft support portion. Then, the shaft member can be easily attached to the cylinder head by passing the shaft member through the hole of the first shaft support portion, the collar member of the temporary assembly, and the hole of the second shaft support portion. Thereby, the enlargement of the hole of the first shaft support portion and the second shaft support portion can be suppressed, and the assemblability can be improved. The collar member can also be rotatable with respect to the shaft member. There is a case where the first rocker arm and the second rocker arm are pressed against the rocking shaft due to the tolerance of the mounting position of the first rocker arm and the second rocker arm. In this case, the increase in the driving loss of the first rocker arm and the second rocker arm can be suppressed by rotating the collar member with respect to the shaft member. The first shaft support portion may also include a rocking shaft hole and a cam shaft hole. The first end portion can also be inserted into the rocking shaft hole. The camshaft hole may also be disposed adjacent to the rocking shaft hole. A camshaft can also be inserted into the camshaft bore. When the camshaft hole is disposed adjacent to the rocking shaft hole, it is difficult to secure the wall thickness of the first shaft support portion. However, in the engine for a straddle type vehicle of the present aspect, the outer diameter of the first end portion is smaller than the outer diameter of the collar member, so that the wall thickness of the first shaft support portion can be easily ensured. The inner diameter of the rocking shaft hole may also be smaller than the outer diameter of the collar member. In this case, the wall thickness of the first shaft support portion can be easily ensured. The pressing member may be integrally formed with the first rocker arm. In this case, the configuration of the shaking unit can be simplified. The straddle type vehicle engine may further include a poppet member that pushes the pin. In this case, the connection and release of the pressing member by the second rocker arm can be switched by a simple configuration. The first contact portion may have a slider shape integrally provided on the first rocker arm. In this case, the first rocker arm can be made lighter than in the case where the roller is provided. The second contact portion may have a slider shape integrally provided on the second rocker arm. In this case, the second rocker arm can be made lighter than in the case where the roller is provided. The first rocker arm may include a first arm portion that supports the first contact portion. The first contact portion may be a first roller that is rotatably supported by the first arm portion. The second rocker arm may include a second arm portion that supports the second contact portion. The second contact portion may be a second roller that is rotatably supported by the second arm portion. In this case, the first roller or the second roller rotates with respect to the cam shaft. Thereby, compared with the case where the slider shape is provided and the camshaft is slid, the drive loss is easily suppressed even if the contact part is not subjected to special surface treatment. The first rocker arm may include a first arm portion that supports the first contact portion. The first contact portion may be a first roller that is rotatably supported by the first arm portion. The second contact portion may be in the shape of a slider integrally provided on the second rocker arm. In this case, the advantages of the first roller and the slider shape can be sufficiently exhibited in accordance with the operation region before and after the switching. The straddle type vehicle engine may further include a head cover attached to the cylinder head. The cylinder head may also include a sidewall end that is butted to the head cover. The first shaft support portion may protrude toward the head cover side more than the side wall end. In this case, the rigidity of the portion where the first shaft support portion protrudes toward the head cover side from the side wall end is likely to be low, and the stress during the operation of the engine is likely to increase. However, in the engine for a straddle type vehicle of the present aspect, by using the collar member, the enlargement of the hole provided in the first shaft support portion can be suppressed. Thereby, the crack of the first shaft support portion can be sufficiently suppressed. The boundary between the first rocker arm and the second rocker arm may be disposed closer to the first shaft support portion side or the second shaft support portion side than the intermediate position between the first shaft support portion and the second shaft support portion. In this case, in the high-speed region of the engine rotational speed, if the rocking shaft is bent and deformed around the boundary between the first rocker arm and the second rocker arm, the first shaft support portion or the second shaft support portion may be Will cause greater stress. In the engine for a straddle type vehicle of this aspect, the bending deformation of the rocking shaft can be reduced by increasing the joint rigidity of the rocking unit. The engine can also be a single cylinder engine. The second aspect of the straddle type vehicle includes the above engine. In this case, it is possible to provide a straddle type vehicle which is excellent in layout by suppressing an engine having a small size of a cylinder head.

Hereinafter, an engine for a straddle type vehicle and a straddle type vehicle according to an embodiment will be described with reference to the drawings. FIG. 1 is a side view of a straddle type vehicle 100. The straddle type vehicle 100 is a so-called speed skating type motorcycle. As shown in FIG. 1, the straddle type vehicle 100 includes a front wheel 101, a seat portion 102, a rear wheel 103, a power unit 104, a steering device 105, and a vehicle body casing 106. The front wheel 101 is rotatably supported by the steering device 105. A handle 113 is attached to the upper end of the steering device 105. The seat portion 102 is disposed behind the steering device 105. The power unit 104 is disposed below the seat portion 102. The power unit 104 includes an engine 1 and a gearbox 107. The power unit 104 supports the rear wheel 103 and is rotatable. The body casing 106 includes a rear casing 108, a bottom casing 109, and a front casing 110. The rear outer casing 108 is disposed below the seat portion 102. The front outer casing 110 covers the periphery of the steering device 105. The bottom case 109 is disposed between the front case 110 and the rear case 108. The upper surface of the bottom case 109 includes a leg portion 111 and a channel portion 112. The channel portion 112 is provided at a central portion in the vehicle width direction of the upper surface of the bottom case 109. The channel portion 112 protrudes upward from the leg portion 111. The leg portion 111 is disposed on the left and right of the channel portion 112. The footrest portion 111 is provided in such a manner that the rider places the foot. Furthermore, the channel portion 112 can also be omitted. That is, the upper surface of the bottom case 109 may have a flat leg portion extending in the left-right direction. Fig. 2 is a cross-sectional view showing a part of the engine 1 for a straddle type vehicle according to the embodiment. In the present embodiment, the engine 1 is a water-cooled single-cylinder engine. As shown in FIG. 2, the engine 1 includes a crankcase 2, a cylinder block 3, a cylinder head 4, and a head cover 5. The crankcase 2 houses the crankshaft 6. The cylinder block 3 is connected to the crankcase 2. The cylinder block 3 and the crankcase 2 may be integral or may be independent individuals. The cylinder block 3 houses the piston 7. The piston 7 is coupled to the crankshaft 6 via a connecting rod 8. Further, in the present embodiment, the direction from the cylinder head 4 toward the head cover 5 in the cylinder axis Ax1 direction of the cylinder block 3 is referred to as "head cover side". Further, the direction from the cylinder head 4 toward the cylinder block 3 in the cylinder axis Ax1 direction is referred to as "cylinder block side". The cylinder head 4 is disposed on the head cover side of the cylinder block 3. The cylinder head 4 is mounted to the cylinder block 3. The head cover 5 is disposed on the head cover side of the cylinder head 4. The head cover 5 is mounted to the cylinder head 4. 3 is a cross-sectional view of the cylinder head 4 and the head cover 5 as viewed from a direction perpendicular to the cylinder axis Ax1 and the cam axis Ax3. As shown in Fig. 3, the cylinder head 4 includes a side wall 4a extending in the cylinder axis Ax1 direction. The head cover 5 includes a side wall 5a extending in the direction of the cylinder axis Ax1. The end portion 4b of the side wall 4a of the cylinder head 4 (hereinafter referred to as "side wall end 4b") abuts against the end portion 5b of the side wall 5a of the head cover 5 (hereinafter referred to as "side wall end 5b"). In detail, the side wall end 4b of the cylinder head 4 is butted to the side wall end 5b of the head cover 5 via the seal member 9. Furthermore, the cylinder head 4 and the cylinder block 3 may be independent bodies or may be integrated. As shown in FIG. 2, the cylinder axis Ax1 is perpendicular to the center axis Ax2 of the crankshaft 6 (hereinafter referred to as "crank axis Ax2"). The cylinder head 4 contains a combustion chamber 11. A spark plug 12 is mounted to the cylinder head 4. The front end of the spark plug 12 is disposed facing the combustion chamber 11. The base end of the Mars plug 12 is disposed outside of the engine 1. A valve actuation mechanism 13 is housed in the cylinder head 4 and the head cover 5. The valve actuation mechanism 13 is a mechanism for opening and closing the following exhaust valves 25 and 26 and the intake valves 27 and 28. The valve actuation mechanism 13 employs a SOHC (Single Over Head Camshaft) type mechanism. The valve actuation mechanism 13 employs a so-called variable valve mechanism that switches the opening and closing timing of the intake valves 27 and 28. The valve actuation mechanism 13 includes a camshaft 14. The camshaft 14 is supported by the cylinder head 4. The central axis Ax3 of the camshaft 14 (hereinafter referred to as "cam axis Ax3") is perpendicular to the cylinder axis Ax1. The cam axis Ax3 is parallel to the crankshaft axis Ax2. As shown in FIG. 3, the camshaft 14 includes a first camshaft end portion 141 and a second camshaft end portion 142. A sprocket 29 is attached to the first camshaft end portion 141. The cam chain 15 shown in Fig. 2 is wound around the sprocket 29. As shown in FIG. 2, a cam chain chamber 16 is provided in the cylinder head 4 and the cylinder block 3. The cam chain 15 is disposed in the cam chain chamber 16. The camshaft 14 is coupled to the crankshaft 6 via a cam chain 15 . The rotation of the crankshaft 6 is transmitted to the camshaft 14 via the cam chain 15, whereby the camshaft 14 is rotated. A water pump 17 is coupled to the first camshaft end portion 141. The water pump 17 is connected to a coolant passage (not shown) and a radiator 19 in the engine 1 via a coolant hose 18. The water pump 17 is driven by the rotation of the cam shaft 14, thereby circulating the coolant of the engine 1. As shown in FIG. 3, the camshaft 14 includes a rod portion 143, a first intake cam portion 144, a second intake cam portion 145, and an exhaust cam 146. The rod portion 143 is rotatably supported by the first shaft support portion 21 and the second shaft support portion 22 of the cylinder head 4. The first intake cam portion 144 , the second intake cam portion 145 , and the exhaust cam 146 are disposed on the outer circumference of the rod portion 143 . The first intake cam portion 144, the second intake cam portion 145, and the exhaust cam 146 are arranged side by side in the cam axis Ax3 direction. 4 and 5 are perspective views of the inside of the cylinder head 4. Fig. 6 is a view of the inside of the cylinder head 4 as viewed from the cylinder axis Ax1 direction. As shown in FIGS. 3 to 6 , the cylinder head 4 includes a first shaft support portion 21 and a second shaft support portion 22 . The first shaft support portion 21 and the second shaft support portion 22 are integrally formed with the cylinder head 4 . The first shaft support portion 21 and the second shaft support portion 22 are arranged side by side in the cam axis Ax3 direction. The first shaft support portion 21 and the second shaft support portion 22 support the cam shaft 14 and are rotatable. As shown in FIG. 3, the first shaft support portion 21 includes a first cam shaft hole 211 into which the cam shaft 14 is inserted. The first bearing 23 is attached to the first camshaft hole 211. The first shaft support portion 21 supports the cam shaft 14 via the first bearing 23 . The second shaft support portion 22 includes a second cam shaft hole 221 into which the cam shaft 14 is inserted. The second bearing 24 is attached to the second camshaft hole 221. The second shaft support portion 22 supports the cam shaft 14 via the second bearing 24 . The end portion 21a on the head cover side of the first shaft support portion 21 is located closer to the head cover than the side wall end 4b of the cylinder head 4. In other words, the first shaft support portion 21 protrudes toward the head cover side from the side wall end 4b of the cylinder head. The end portion 22a on the head cover side of the second shaft support portion 22 is located closer to the head cover than the side wall end 4b of the cylinder head 4. In other words, the second shaft support portion 22 protrudes toward the head cover side from the side wall end 4b of the cylinder head 4. As shown in FIG. 6, the intake valves 27 and 28 and the exhaust valves 25 and 26 are attached to the cylinder head 4. Figure 7 is a cross-sectional view of the inside of the cylinder head 4 as seen from the direction of the cam axis Ax3. As shown in FIG. 7, the cylinder head 4 includes an intake port 31 and an exhaust port 32 that communicate with the combustion chamber 11. The intake valves 27 and 28 open and close the intake port 31. As shown in FIG. 6, the intake valves 27 and 28 include a first intake valve 27 and a second intake valve 28. The first intake valve 27 and the second intake valve 28 are arranged side by side in the direction of the cam axis Ax3. As shown in FIG. 4, an intake valve spring 271 is attached to the first intake valve 27. The intake valve spring 271 pushes the first intake valve 27 in a direction in which the first intake valve 27 closes the intake port 31. Similarly to the second intake valve 28, the intake valve spring 281 is attached, and the second intake valve 28 is pushed in the direction in which the second intake valve 28 closes the intake port 31. The exhaust valves 25 and 26 open and close the exhaust port 32. The exhaust valves 25 and 26 include a first exhaust valve 25 and a second exhaust valve 26. The first exhaust valve 25 and the second exhaust valve 26 are arranged side by side in the direction of the cam axis Ax3. As shown in FIG. 5, an exhaust valve spring 251 is attached to the first exhaust valve 25. The exhaust valve spring 251 pushes the first exhaust valve 25 in a direction in which the first exhaust valve 25 closes the exhaust port 32. The exhaust valve spring 261 is attached to the second exhaust valve 26, and the second exhaust valve 26 is pushed in the direction in which the second exhaust valve 26 closes the exhaust port 32. As shown in FIG. 7, the valve actuation mechanism 13 includes an exhaust swing unit 33 and an intake swing unit 34. The exhaust swaying unit 33 presses the exhaust valves 25 and 26 to open and close the exhaust valves 25 and 26. The intake swing unit 34 presses the intake valves 27 and 28 to open and close the intake valves 27 and 28. The exhaust rocking unit 33 and the intake rocking unit 34 are driven by a camshaft 14. The exhaust swing unit 33 includes an exhaust swing shaft 35, an exhaust rocker arm 36, and a pressing member 38. The exhaust rocking shaft 35 is disposed in parallel with the cam shaft 14. The exhaust rocker shaft 35 is supported by the cylinder head 4. Specifically, the exhaust rocking shaft 35 is supported by the first shaft support portion 21 and the second shaft support portion 22 . The exhaust rocker arm 36 is swingably supported by the exhaust rocking shaft 35 around the exhaust rocking shaft 35. The exhaust rocker arm 36 can be provided to operatively operate the exhaust valves 25 and 26. The exhaust rocker arm 36 includes a roller 37 and an arm portion 39. The arm portion 39 includes a through hole 364 through which the exhaust rocker shaft 35 passes. As shown in Figure 6, the arm 39 supports the roller 37 and is rotatable. The central axis of rotation of the roller 37 is parallel to the cam axis Ax3. The roller 37 is in contact with the exhaust cam 146 and is rotated by the rotation of the exhaust cam 146. The pressing member 38 is formed integrally with the arm portion 39. As shown in FIGS. 5 and 6, the first adjustment screw 365 and the second adjustment screw 366 are provided at the front end of the pressing member 38. The front end of the first adjustment screw 365 faces the base end of the first exhaust valve 25. As shown in FIG. 7, the front end of the second adjustment screw 366 is opposed to the base end of the second exhaust valve 26. When the roller 37 is pushed up by the exhaust cam 146, the exhaust rocker arm 36 swings, whereby the pressing member 38 presses the first exhaust valve 25 and the second exhaust valve 26. Thereby, the exhaust port 32 is opened. When the roller 37 is not pushed up by the exhaust cam 146, the first exhaust valve 25 and the second exhaust valve 26 are pushed up by the exhaust valve springs 251 and 261, thereby closing the exhaust port 32. . FIG. 8 is a perspective view of the intake rocking unit 34. Figure 9 is a view of the intake rocking unit as viewed from a direction perpendicular to the cam axis. As shown in FIGS. 8 and 9, the intake rocking unit 34 includes an intake rocking shaft 41, a first rocker arm 42, a second rocker arm 43, a pressing member 44 (see FIG. 6), and a coupling pin 45. The intake rocking shaft 41 is disposed in parallel with the cam shaft 14. The intake rocking shaft 41 is supported by the cylinder head 4. Specifically, the intake rocking shaft 41 is supported by the first shaft support portion 21 and the second shaft support portion 22 . The first rocker arm 42 is swingably supported by the intake rocking shaft 41 around the intake rocking shaft 41. The first rocker arm 42 can be provided to operate the intake valves 27 and 28. As shown in FIG. 3, the first rocker arm 42 includes a first mounting portion 421. The first attachment portion 421 is provided in a hole of the first rocker arm 42. The intake rocking shaft 41 passes through the first mounting portion 421. The first rocker arm 42 includes a first connection hole 422. The first coupling hole 422 is located closer to the head cover than the intake rocking shaft 41. The first coupling hole 422 extends in the direction of the cam axis Ax3. The coupling pin 45 is inserted into the first coupling hole 422. As shown in FIG. 8 , the first rocker arm 42 includes a first arm portion 420 and a first contact portion 423 . The first contact portion 423 is provided in contact with the first intake cam portion 144. The first contact portion 423 is rotatably supported by the roller of the first arm portion 420. The first contact portion 423 is rotated by the rotation of the first intake cam portion 144. The central axis of rotation of the first contact portion 423 is parallel to the cam axis Ax3. The first rocker arm 42 rotates about the axis of the intake rocking shaft 41 by bringing the first contact portion 423 into contact with the first intake cam portion 144. As shown in FIG. 7, the second rocker arm 43 is swingably supported around the intake rocking shaft 41. The second rocker arm 43 is arranged side by side with the first rocker arm 42 in the direction of the cam axis Ax3. The second rocker arm 43 is disposed on the cam chain chamber 16 side of the first rocker arm 42. As shown in FIG. 3, the second rocker arm 43 includes a second attachment portion 431. The second attachment portion 431 is provided in a hole of the second rocker arm 43. The intake rocking shaft 41 passes through the second attachment portion 431. The second rocker arm 43 includes a second coupling hole 432. The second coupling hole 432 is located closer to the head cover than the intake rocking shaft 41. The second coupling hole 432 extends in the direction of the cam axis Ax3. The second connection hole 432 is disposed so as to overlap the first connection hole 422 in the direction of the cam axis Ax3. Therefore, the coupling pin 45 can be inserted into the second coupling hole 432 of the second coupling hole 432. As shown in FIG. 8 , the second rocker arm 43 includes a second arm portion 430 and a second contact portion 433 . The second contact portion 433 is in contact with the second intake cam portion 145 and is slidably provided to the second intake cam portion 145. The second arm portion 430 is formed integrally with the second contact portion 433. The second contact portion 433 has a slider shape integrally provided to the second rocker arm 43. For example, the second contact portion 433 includes a hardened layer formed by surface treatment. The hardened layer has a hardness higher than that of the base of the second rocker arm 43. The substrate is, for example, chromium molybdenum steel. The hardened layer is, for example, DLC (diamond-like carbon). The second rocker arm 43 is rotated about the axis of the intake rocking shaft 41 by sliding the second contact portion 433 against the second intake cam portion 145. As shown in FIG. 6, the pressing member 44 is connected to the first rocker arm 42. The pressing member 44 is formed integrally with the first rocker arm 42. The first adjustment screw 441 and the second adjustment screw 442 are provided at the front end of the pressing member 44. The front end of the first adjustment screw 441 is opposed to the base end of the first intake valve 27. The front end of the second adjustment screw 442 is opposed to the base end of the second intake valve 28. The pressing member 44 rotates in the axial direction of the intake rocking shaft 41 to press the first intake valve 27 and the second intake valve 28 . The intake swing unit 34 includes an arm spring member 46, a first support member 47, and a second support member 48. The arm spring pushing member 46 pushes the second rocker arm 43 in a direction in which the second contact portion 433 is pressed against the cam shaft 14. In the present embodiment, the arm spring pushing member 46 is a coil spring, and the intake rocking shaft 41 passes through the arm spring pushing member 46. The first support member 47 supports one end of the arm spring member 46. The first support member 47 has a pin shape and protrudes from the second rocker arm 43 in the cam axis Ax3 direction. The second support member 48 supports the other end of the arm spring member 46. The second support member 48 is composed of a bent plate material. FIG. 10 is a cross-sectional view of the vicinity of the second shaft support portion 22 and the arm spring pushing member 46. As shown in FIG. 10, the second shaft support portion 22 is provided with a step portion 222, and the second support member 48 is supported by the step portion 222. As shown in FIG. 3, the coupling pin 45 is provided to be movable in the axial direction of the cam shaft 14 and is movable to the coupling position and the release position. The coupling pin 45 is disposed at the connection position over the first connection hole 422 and the second connection hole 432. Thereby, the coupling pin 45 connects the first rocker arm 42 and the second rocker arm 43. In other words, the connecting pin 45 connects the pressing member 44 to the second rocker arm 43 via the first rocker arm 42 at the connecting position. Thereby, the pressing member 44 swings integrally with the first rocker arm 42 and the second rocker arm 43. The coupling pin 45 is disposed in the first coupling hole 422 at the release position, and is not disposed in the second coupling hole 432. Thereby, the first rocker arm 42 and the second rocker arm 43 are non-connected at the release position by the joint pin 45. In other words, the coupling pin 45 releases the second rocker arm 43 from the pressing member 44 at the release position. Thereby, the pressing member 44 and the first rocker arm 42 swing independently of the second rocker arm 43. The valve actuation mechanism 13 includes an opening/closing point changing unit 49. The opening/closing timing changing unit 49 changes the opening and closing timing of the first intake valve 27 and the second intake valve 28. The opening/closing point changing unit 49 is attached to the head cover 5. The opening/closing point changing unit 49 is an electromagnetic solenoid, and when the coupling pin 45 is pressed in the axial direction of the cam shaft 14 by energization, the position of the coupling pin 45 is switched from the release position to the connection position. When the energization of the opening/closing timing changing unit 49 is stopped, the position of the coupling pin 45 is returned from the connection position to the release position by the elastic force of the pin pushing member 59 described below. The opening/closing point changing unit 49 includes a rod 491 that presses the coupling pin 45 and a body portion 492 that drives the rod 491. The central axis of the rod 491 is parallel to the cam axis Ax3. The rod 491 is disposed so as to overlap the joint pin 45 when viewed in the direction of the cam axis Ax3 in the swing range of the joint pin 45. The lever 491 is driven by the body portion 492, thereby pressing the coupling pin 45. As shown in FIG. 3, the intake rocking unit 34 includes a pin pushing member 59. The pin spring pushing member 59 is disposed in the first coupling hole 422. The pin pushing member 59 pushes the coupling pin 45 in a direction from the connection position toward the release position. Therefore, when the joint pin 45 is not pressed by the opening/closing point changing unit 49, the joint pin 45 is held at the release position by the pin spring pushing member 59. When the joint pin 45 is pressed by the opening/closing point changing unit 49, the joint pin 45 moves from the release position to the joint position against the elastic thrust of the pin spring pushing member 59. FIG. 11 shows a state in which the second contact portion 433 is pushed up by the second intake cam portion 145 when the coupling pin 45 is at the connection position. When the joint pin 45 is at the joint position, the first rocker arm 42 is coupled to the second rocker arm 43 and swings integrally with the second rocker arm 43. Therefore, when the second contact portion 433 is pushed up by the second intake cam portion 145, the second rocker arm 43 swings around the intake rocking shaft 41, whereby the first rocker arm 42 also lowers the pressing member 44. swing. Thereby, the first intake valve 27 is pressed down at the front end of the first adjustment screw 441, and the second intake valve 28 is pressed down at the front end of the second adjustment screw 442. Thereby, the first intake valve 27 and the second intake valve 28 open the intake port 31. As a result, the pressing member 44 presses the first intake valve 27 and the second intake valve 28 in accordance with the rotation of the second rocker arm 43 when the coupling pin 45 is at the coupling position. When the second contact portion 433 is not pushed up by the second intake cam portion 145, the first intake valve 27 and the second intake valve 28 are pushed up by the intake valve springs 271 and 281 to move the intake port 31. shut down. When the joint pin 45 is at the release position, the first rocker arm 42 and the second rocker arm 43 swing independently. Therefore, when the first contact portion 423 is pushed up by the first intake cam portion 144, the first rocker arm 42 swings in the direction in which the pressing member 44 is lowered around the intake rocking shaft 41. Thereby, the first intake valve 27 is pressed down at the front end of the first adjustment screw 441, and the second intake valve 28 is pressed down at the front end of the second adjustment screw 442. Thereby, the first intake valve 27 and the second intake valve 28 open the intake port 31. As a result, the pressing member 44 presses the first intake valve 27 and the second intake valve 28 in accordance with the rotation of the first rocker arm 42 when the coupling pin 45 is at the release position. When the first contact portion 423 is not pushed up by the first intake cam portion 144, the first intake valve 27 and the second intake valve 28 are pushed up by the intake valve springs 271 and 281 to move the intake port 31. shut down. Further, the shape of the first intake cam portion 144 and the second intake cam portion 145 is such that the second intake cam portion 145 is second before the first end of the first intake cam portion 144 reaches the first contact portion 423 The contact portion 433 is pushed up to set. Therefore, when the coupling pin 45 is at the coupling position, the first rocker arm 42 is operated by the rotation of the second intake cam portion 145, whereby the rotation of the first intake cam portion 144 is not transmitted to the first rocker arm. 42. Therefore, when the coupling pin 45 is at the connection position, the first intake valve 27 and the second intake valve 28 are opened and closed in response to the rotation of the second intake cam portion 145. On the other hand, when the joint pin 45 is at the release position, the rotation of the second intake cam portion 145 is not transmitted to the first rocker arm 42. Therefore, when the joint pin 45 is at the release position, the first intake valve 27 and the second intake valve 28 are opened and closed in response to the rotation of the first intake cam portion 144. Next, the configuration of the intake rocking shaft 41 will be described in detail. Figure 12 is a perspective view of the intake rocker shaft 41. As shown in FIG. 12, the intake rocking shaft 41 includes a shaft member 51 and a collar member 52. The shaft member 51 and the collar member 52 are independent of each other. The collar member 52 has a tubular shape. The shaft member 51 is inserted into the hole 521 of the collar member 52. The shaft member 51 is not fixed to the collar member 52. Therefore, the collar member 52 can rotate with respect to the shaft member 51. The shaft member 51 includes a first end portion 511 and a second end portion 512. The first end portion 511 is one end portion of the intake rocking shaft 41 in the axial direction. The second end portion 512 is the other end portion of the intake rocking shaft 41 in the axial direction. The first end portion 511 protrudes from the collar member 52 in one of the axial directions of the intake rocking shaft 41. The second end portion 512 protrudes from the collar member 52 toward the other of the axial direction of the intake rocking shaft 41. As shown in FIG. 3, the first end portion 511 is supported by the first shaft support portion 21. The first shaft support portion 21 includes a first rocking shaft hole 212. The first rocking shaft hole 212 is disposed adjacent to the first camshaft hole 211. The first rocking shaft hole 212 penetrates the first shaft support portion 21 in the direction of the cam axis Ax3. The first end portion 511 is inserted into the first rocking shaft hole 212. The end surface of the first end portion 511 faces the cam chain chamber 16 and is disposed. The second end portion 512 is supported by the second shaft support portion 22 . The second shaft support portion 22 includes a second rocking shaft hole 223. The second rocking shaft hole 223 is disposed adjacent to the second cam shaft hole 221. The second rocking shaft hole 223 does not penetrate the second shaft support portion 22 . Further, the second rocking shaft hole 223 may also pass through the second shaft support portion 22. The second end portion 512 is inserted into the second rocking shaft hole 223. As shown in FIG. 8, the boundary B between the first connection hole 422 of the first rocker arm 42 and the second connection hole 432 of the second rocker arm 43 is intermediate to the interval L between the first end portion 511 and the second end portion 512. M is closer to the second end 512. More specifically, the distance L2 from the boundary B to the second end portion 512 is smaller than the distance L1 (L2 < L1) from the boundary B to the first end portion 511. As shown in FIG. 12, a locking groove 513 is provided on the end surface of the first end portion 511. The shaft member 51 can be attached to and detached from the first camshaft hole 211 by locking the tool to the locking groove 513. A locking hole 514 is formed in the second end portion 512. The locking hole 514 penetrates the second end portion 512 in a direction perpendicular to the axis of the shaft member 51. As shown in FIG. 5, the second shaft support portion 22 is provided with a hole 224 extending perpendicularly to the axial direction of the second rocking shaft hole 223. The hole 224 is open to the upper surface of the second shaft support portion 22. By inserting the fastening member 53 shown in FIG. 6 into the hole 224 of the second shaft support portion 22 and the locking hole 514 of the second end portion 512, the shaft member 51 is prevented from coming off the second shaft support portion 22. The collar member 52 and the shaft member 51 are separate bodies. The collar member 52 is disposed between the first end portion 511 and the second end portion 512 in the axial direction of the intake rocking shaft 41. The collar member 52 is disposed between the first shaft support portion 21 and the second shaft support portion 22 . The first rocker arm 42 and the second rocker arm 43 are attached to the collar member 52. In other words, the collar member 52 is inserted into the first mounting portion 421 of the first rocker arm 42 and the second mounting portion 431 of the second rocker arm 43. The arm spring pushing member 46 and the second support member 48 are also attached to the collar member 52. The outer diameter of the collar member 52 is larger than the outer diameter of the shaft member 51. The outer diameter of the collar member 52 is larger than the outer diameter of the exhaust rocker shaft 35. The outer diameter of the collar member 52 is larger than the outer diameter of the first end portion 511 and larger than the outer diameter of the second end portion 512. The inner diameter of the first rocking shaft hole 212 is smaller than the outer diameter of the collar member 52. The inner diameter of the second rocking shaft hole 223 is smaller than the outer diameter of the collar member 52. In the straddle-type vehicle engine 1 of the present embodiment described above, the outer diameter of the collar member 52 to which the first rocker arm 42 and the second rocker arm 43 are attached is larger than the first end portion 511 of the shaft member 51. The outer diameter is larger than the outer diameter of the second end portion 512 of the shaft member 51. Thereby, the connection rigidity of the intake and swing unit 34 can be increased, and the increase in the inertial mass can be suppressed. Further, the outer diameter of the first end portion 511 is smaller than the outer diameter of the collar member 52. Therefore, the expansion of the first rocking shaft hole 212 of the first shaft support portion 21 can be suppressed. As described above, the first rocking shaft hole 212 is disposed adjacent to the first camshaft hole 211. Therefore, when the outer diameter of the first rocking shaft hole 212 is increased, the thickness between the first rocking shaft hole 212 and the first cam shaft hole 211 is reduced, and the first shaft support portion 21 is likely to be broken. When the outer diameter of the first rocking shaft hole 212 is increased and the thickness between the first rocking shaft hole 212 and the first cam shaft hole 211 is increased, the entire first shaft support portion 21 is enlarged, and the cylinder is worried. The size of the first 4 is large. However, in the present embodiment, the expansion of the first rocking shaft hole 212 can be suppressed in accordance with the structure of the intake rocking shaft 41. Therefore, it is possible to suppress the occurrence of cracking in the first shaft support portion 21, and it is possible to suppress an increase in size of the cylinder head 4. Similarly, by making the outer diameter of the second end portion 512 smaller than the outer diameter of the collar member 52, the expansion of the second rocking shaft hole 223 of the second shaft support portion 22 can be suppressed. Therefore, it is possible to suppress the occurrence of cracking in the second shaft support portion 22, and it is possible to suppress an increase in size of the cylinder head 4. Further, in the present embodiment, the first shaft support portion 21 protrudes toward the head cover side from the side wall end 4b. Therefore, the end portion 21a on the head cover side of the first shaft support portion 21 is not supported by the other portion of the cylinder head 4 and becomes a free end. 13 and 14 show the cylinder head 4 of the first modification. In the cylinder head 4 of the first modification, the end portion 21a of the first shaft support portion 21 and the side wall end 4b are located at the same position in the cylinder axis direction so that the side wall end 4b is located closer to the head cover side. In the first modification, the end portion 21a of the first shaft support portion 21 can be connected to the side wall 4a of the cylinder head 4 to be supported. Therefore, the rigidity of the first shaft support portion 21 is high. On the other hand, when the first shaft support portion 21 protrudes toward the head cover side from the side wall end 4b as in the present embodiment, the end portion 21a of the first shaft support portion 21 is supported by the cylinder head 4 in a cantilever state. Therefore, the rigidity of the protruding portion of the first shaft support portion 21 is lowered, and the stress generated by the first shaft support portion 21 is likely to increase when the engine 1 is operated. In the present embodiment, even in such a configuration, the expansion of the first rocking shaft hole 212 can be suppressed by using the collar member 52. Thereby, the crack of the first shaft support portion 21 can be sufficiently suppressed. Further, since the second shaft support portion 22 protrudes toward the head cover side from the side wall end 4b, the rigidity of the second shaft support portion 22 is lowered as in the first shaft support portion 21, and the second shaft support portion is operated when the engine 1 is operated. The stress generated by 22 is easily increased. However, even in such a configuration, the expansion of the second rocking shaft hole 223 can be suppressed by using the collar member 52. Thereby, the rupture of the second shaft support portion 22 can be sufficiently suppressed. Further, as shown in FIG. 15, there is a case where the shaft member 51 is bent and deformed around the boundary B between the first rocker arm 42 and the second rocker arm 43. For example, when the rotation speed of the engine is increased in a state where the first rocker arm 42 and the second rocker arm 43 are not connected due to a failure of the point changing unit 49 or a breakage of the coupling pin 45, the degree of such deformation is increased. . When the position of the boundary B is closer to the second shaft support portion 22 than the first shaft support portion 21 as in the present embodiment, the degree of bending deformation at the position close to the second shaft support portion 22 is increased. In this case, the second shaft support portion 22 may generate a large stress. That is, in this case, the coupling rigidity can be increased by attaching the collar member 52 to the shaft member 51, so that the degree of bending deformation can be reduced as compared with the case where the collar member 52 is not attached. Thereby, the stress generated by the second shaft support portion 22 can be suppressed to be small. Furthermore, even if the position of the boundary B is at the intermediate position M, the same deformation occurs. In this case, the stress generated by the second shaft support portion 22 is reduced as compared with the above-described embodiment, and the stress suppressing effect by the collar member 52 can of course be obtained. Further, the collar member 52 and the shaft member 51 are independent members, and the shaft member 51 is inserted into the hole 521 of the collar member 52. Therefore, when the engine 1 is assembled, the collar member 52 is passed through the first rocking shaft hole 212 and the second rocking shaft hole 223, and only the shaft member 51 passes through the first rocking shaft hole 212 and the second rocking shaft hole 223. Thereby, the intake rocking shaft 41 can be attached to the first shaft support portion 21 and the second shaft support portion 22. Thereby, the expansion of the first rocking shaft hole 212 and the second rocking shaft hole 223 can be suppressed, and good assemblability can be ensured. Further, the first rocker arm 42 has a roller as the first contact portion 423, and the second rocker arm 43 includes a slider shape as the second contact portion 433. Since the first contact portion 423 is a roller, the driving loss of the rocking shaft in the low speed region can be reduced as compared with the case where the first contact portion 423 is formed into a slider shape and subjected to surface treatment. On the other hand, since the second contact portion 433 has a slider shape, the inertial mass which is increased in influence in the high-speed region can be reduced as compared with the case where the second contact portion 433 is used as a roller, and can be suppressed as The same drive loss. The embodiment of the present invention has been described above, but the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit and scope of the invention. The engine is not limited to a water-cooled single-cylinder engine. For example, the engine can also be air cooled. The engine can also be a multi-cylinder engine. The number of valves for exhaust is not limited to two, and may be one or three or more. The number of intake valves is not limited to two, and may be one or three or more. The configuration and arrangement of the valve mechanism 13 can also be changed. For example, the first contact portion 423 may be a slider that is integrally provided to the first rocker arm 42. That is, both the first contact portion 423 and the second contact portion 433 may be sliders. Alternatively, as in the second variation shown in FIG. 16, the first contact portion 423 is a first roller rotatably supported by the first arm portion 420, and the second contact portion 433 is rotatably supported by the second arm. The second roller of the portion 430. In the above-described embodiment, the intake valve is a mechanism for switching the opening and closing timing of the valve by the opening/closing point changing unit 49. However, this mechanism may be employed for the exhaust valve. The configuration including the rocking shaft of the shaft member 51 and the collar member 52 can also be applied to the exhaust rocking shaft. The collar member 52 can also be mounted to the shaft member 51 in a non-rotatable manner. Similarly to the third modification shown in FIG. 17, the pressing member 44 and the first rocker arm 42 and the second rocker arm 43 may be independent members. For example, when the connecting pin 45 is at the connecting position, the second rocker arm 43 and the pressing member 44 may be coupled by the connecting pin 45. When the connecting pin 45 is at the releasing position, the first rocking is performed by the connecting pin 45. The arm 42 is coupled to the pressing member 44. The joint pin 45 can also be driven by a hydraulic pump (a point change portion at the time of opening and closing). For example, in the fourth variation shown in FIG. 18, the first oil chamber 42r and the oil passage 42m are formed in the first rocker arm 42. The oil of the first oil chamber 42r can be pressurized and depressurized via the oil passage 42m. Similarly, the second oil chamber 43r and the oil passage 43m are formed in the second rocker arm 43. The oil of the second oil chamber 43r can be pressurized and depressurized via the oil passage 43m. A pin hole 45r is formed in the pressing member 44. The pin hole 45r communicates with the first oil chamber 42r and the second oil chamber 43r. A coupling pin 45 is housed in the pin hole 45r. In this configuration, the connecting pin 45 is displaced by the hydraulic pressure, whereby the pressing member 44 can be selectively coupled to the first rocker arm 42 and the second rocker arm 43. As in the fifth modification shown in FIG. 19, the first rocker arm 42 and the second rocker arm 43 may be provided with pressing members 44a and 44b, respectively. In other words, the first rocker arm 42 may be provided with the first pressing member 44a, and the second rocker arm 43 may be provided with the second pressing member 44b. In this case, when the coupling pin 45 is at the release position, the first pressing member 44a provided in the first rocker arm 42 presses the first intake valve 27 in accordance with the rotation of the first rocker arm 42. Further, when the coupling pin 45 is at the coupling position, the second pressing member 44b provided in the second rocker arm 43 presses the second intake valve 28 in accordance with the rotation of the second rocker arm 43. As shown in FIGS. 13 and 14, at least one of the side wall end 4b and at least one of the end portion 21a of the first shaft support portion 21 and the end portion 22a of the second shaft support portion 22 in the cylinder axis direction may be used. Located in the same location. Further, the end portion 21a of the first shaft support portion 21 and the end portion 22a of the second shaft support portion 22 may be located at different positions in the cylinder axis direction.

1‧‧‧ engine
2‧‧‧Crankcase
3‧‧‧Cylinder block
4‧‧‧ cylinder head
4a‧‧‧ side wall
4b‧‧‧ sidewall end
5‧‧‧ head cover
5a‧‧‧ side wall
5b‧‧‧ sidewall end
6‧‧‧ crankshaft
7‧‧‧Piston
8‧‧‧ Connecting rod
9‧‧‧Seal components
11‧‧‧ combustion chamber
12‧‧‧Mars plug
13‧‧‧Valve mechanism
14‧‧‧Camshaft
15‧‧‧Cam chain
16‧‧‧Cam chain room
17‧‧‧Water pump
18‧‧‧ coolant hose
19‧‧‧ radiator
21‧‧‧1st shaft support
21a‧‧‧End
22‧‧‧2nd axis support
22a‧‧‧End
23‧‧‧1st bearing
24‧‧‧2nd bearing
25‧‧‧1st exhaust valve
26‧‧‧2nd exhaust valve
27‧‧‧1st intake valve
28‧‧‧2nd intake valve
29‧‧‧Sprocket
31‧‧‧Intake 埠
32‧‧‧Exhaust gas
33‧‧‧Exhaust shake unit
34‧‧‧Intake Shake Unit
35‧‧‧Exhaust rocking shaft
36‧‧‧Exhaust rocker arm
37‧‧‧ Roll
38‧‧‧ Pressing members
39‧‧‧ Arms
41‧‧‧Intake shaft
42‧‧‧1st rocker
42m‧‧‧ oil road
42r‧‧‧1st oil room
43‧‧‧2nd rocker
43m‧‧‧ oil road
43r‧‧‧2nd oil room
44‧‧‧ Pressing members
44a‧‧‧1st pressing member
44b‧‧‧2nd pressing member
45‧‧‧Links
45r‧‧ pin hole
46‧‧‧arm push member
47‧‧‧1st support member
48‧‧‧2nd support member
49‧‧‧Change Department when opening and closing
51‧‧‧Axis components
52‧‧‧ collar components
53‧‧‧ fastening members
100‧‧‧Sitting vehicle
101‧‧‧ front wheel
102‧‧‧Site
103‧‧‧ Rear wheel
104‧‧‧Power unit
105‧‧‧Steering device
106‧‧‧ body shell
107‧‧‧Transmission
108‧‧‧ rear casing
109‧‧‧ bottom shell
110‧‧‧ front casing
111‧‧‧Foot
112‧‧‧Channel Department
113‧‧‧Handles
141‧‧‧1st camshaft end
142‧‧‧2nd camshaft end
143‧‧‧ Rod
144‧‧‧1st intake cam section
145‧‧‧2nd intake cam section
146‧‧‧Exhaust cam
211‧‧‧1st camshaft hole
212‧‧‧1st rocking shaft hole
221‧‧‧2nd camshaft hole
222‧‧‧
223‧‧‧2nd shaking shaft hole
224‧‧‧ holes
251‧‧‧Exhaust valve spring
261‧‧‧Exhaust valve spring
271‧‧‧Intake valve spring
281‧‧‧Intake valve spring
364‧‧‧through holes
365‧‧‧1st adjustment screw
366‧‧‧2nd adjustment screw
420‧‧‧1st arm
421‧‧‧1st installation department
422‧‧‧1st link
423‧‧‧1st contact
430‧‧‧2nd arm
431‧‧‧Second Installation Department
432‧‧‧2nd link
433‧‧‧2nd contact
441‧‧‧1st adjustment screw
442‧‧‧2nd adjustment screw
491‧‧‧ drive rod
492‧‧‧ Body Department
511‧‧‧1st end
512‧‧‧2nd end
513‧‧‧ card slot
514‧‧‧Clock hole
521‧‧‧ hole
Ax1‧‧‧Cylinder axis
Ax2‧‧‧ crankshaft axis
Ax3‧‧‧ cam axis
B‧‧‧ Junction
L‧‧‧ interval
L1‧‧‧ distance
L2‧‧‧ distance

Fig. 1 is a side view of a straddle type vehicle of an embodiment. Fig. 2 is a cross-sectional view showing a part of an engine for a straddle type vehicle according to an embodiment. Figure 3 is a cross-sectional view of the cylinder head and the head cover viewed from a direction perpendicular to the cylinder axis and the cam axis. Figure 4 is a perspective view of the interior of the cylinder head. Figure 5 is a perspective view of the interior of the cylinder head. Fig. 6 is a view of the inside of the cylinder head viewed from the cylinder axis direction. Figure 7 is a cross-sectional view of the inside of the cylinder head viewed from the direction of the cam axis. Figure 8 is a perspective view of the intake rocking unit. Figure 9 is a view of the intake rocking unit as viewed from a direction perpendicular to the cam axis. Fig. 10 is a cross-sectional view showing the vicinity of the second shaft support portion and the arm spring pushing member. Figure 11 is a cross-sectional view showing the inside of the cylinder head from the direction of the cam axis. Figure 12 is a perspective view of the intake rocking shaft. Fig. 13 is a perspective view showing the inside of the cylinder head of the first modification. Figure 14 is a cross-sectional view showing a cylinder head of a first modification. Fig. 15 is a view showing a state of change of the intake swing unit. Fig. 16 is a perspective view of the intake rocking unit of the second modification. Fig. 17 is a view showing the intake swing unit of the third modification as seen from the cylinder axis direction. Fig. 18 is a view of the intake swing unit of the fourth modification as seen from the cylinder axis direction. Fig. 19 is a view showing the inside of the cylinder head of the fifth modification from the cylinder axis direction.

4‧‧‧ cylinder head

11‧‧‧ combustion chamber

14‧‧‧Camshaft

26‧‧‧2nd exhaust valve

28‧‧‧2nd intake valve

31‧‧‧Intake 埠

32‧‧‧Exhaust gas

33‧‧‧Exhaust shake unit

34‧‧‧Intake Shake Unit

35‧‧‧Exhaust rocking shaft

36‧‧‧Exhaust rocker arm

38‧‧‧ Pressing members

39‧‧‧ Arms

41‧‧‧Intake shaft

42‧‧‧1st rocker

43‧‧‧2nd rocker

44‧‧‧ Pressing members

45‧‧‧Links

47‧‧‧1st support member

51‧‧‧Axis components

52‧‧‧ collar components

145‧‧‧2nd intake cam section

146‧‧‧Exhaust cam

261‧‧‧Exhaust valve spring

281‧‧‧Intake valve spring

364‧‧‧through holes

366‧‧‧2nd adjustment screw

423‧‧‧1st contact

433‧‧‧2nd contact

442‧‧‧2nd adjustment screw

Claims (14)

An engine for a straddle type vehicle, comprising: a cylinder head; a valve attached to the cylinder head; a rocking unit that presses the valve to open and close the valve; a cam shaft that drives the rocking unit; and a point change portion when opening and closing The rocking unit includes: a rocking shaft supported by the cylinder head; and a first rocker arm including a first mounting portion attached to the rocking shaft and connected to the first a mounting portion and a first contact portion that is disposed in contact with the cam shaft, wherein the first contact portion rotates in contact with the cam shaft about an axis of the rocking shaft; and the second rocker arm includes the above a second mounting portion of the rocking shaft and a second contact portion that is connected to the second mounting portion and that is rotatable in contact with the cam shaft, and is disposed in parallel with the first rocker arm in an axial direction of the rocking shaft The second contact portion rotates about the axis of the rocking shaft by contacting the cam shaft; the pressing member rotates about the axis of the rocking shaft to press the valve; and the connecting pin, The second rocker arm is coupled to the pressing member at the connection position, and the second rocker arm is coupled to the pressing member at the release position by the opening and closing point changing unit being moved to the connection position and the release position. The pressing member is configured such that the connecting pin presses the valve in accordance with the rotation of the first rocker arm at the releasing position, and the connecting pin presses the valve at the connecting position along with the rotation of the second rocker arm, and the cylinder The head includes a first shaft support portion and a second shaft support portion that support the rocking shaft, and the rocking shaft includes: a shaft member including a first end portion and a second end portion, wherein the first end portion is an axis of the rocking shaft One end of the direction is supported by the first shaft support portion, and the second end portion is supported by the other end portion of the rocking shaft in the axial direction and supported by the second shaft support portion; and the collar member is The shaft member is an independent individual and is disposed between the first end portion and the second end portion in the axial direction of the rocking shaft; the first rocker arm and the second rocker arm are attached to the collar structure The outer diameter of the collar member is larger than the outer diameter of the first end portion and larger than the outer diameter of the second end portion, and the shaft member is inserted into the hole of the collar member. A straddle-type vehicle engine according to claim 1, wherein said collar member is rotatable with respect to said shaft member. The engine for a straddle type vehicle according to claim 1, wherein the first shaft support portion includes: a rocking shaft hole through which the first end portion is inserted; and a cam shaft hole that is disposed adjacent to the rocking shaft hole and is provided The above camshaft is inserted. The engine for a straddle type vehicle according to claim 3, wherein the inner diameter of the rocking shaft hole is smaller than the outer diameter of the collar member. The engine for a straddle type vehicle according to claim 1, wherein the pressing member is formed integrally with the first rocker arm. The straddle-type vehicle engine of claim 1, further comprising a spring pushing member that pushes the connecting pin. The straddle-type vehicle engine according to any one of claims 1 to 6, wherein the first contact portion has a slider shape integrally provided with the first rocker arm. The straddle-type vehicle engine according to any one of claims 1 to 6, wherein the second contact portion has a slider shape integrally provided on the second rocker arm. The straddle-type vehicle engine according to any one of claims 1 to 6, wherein the first rocker arm includes a first arm portion that supports the first contact portion, and the first contact portion is rotatably supported by the first The first roller of the one arm portion, the second rocker arm includes a second arm portion that supports the second contact portion, and the second contact portion is rotatably supported by the second roller of the second arm portion. The straddle-type vehicle engine according to any one of claims 1 to 6, wherein the first rocker arm includes a first arm portion that supports the first contact portion, and the first contact portion is rotatably supported by the first The first roller of the one arm portion, and the second contact portion is integrally provided to the slider of the second rocker arm. The straddle-type vehicle engine according to claim 1, further comprising a head cover attached to the cylinder head, wherein the cylinder head includes a side wall end that is butted against the head cover, and the first shaft support portion is closer to the head cover than the side wall end Side protruding. The straddle-type vehicle engine according to claim 1, wherein a boundary between the first rocker arm and the second rocker arm is disposed at a position closer to the first position than a position between the first shaft support portion and the second shaft support portion The shaft support portion side or the second shaft support portion side. The straddle type vehicle engine of claim 1, wherein the engine is a single cylinder engine. A straddle-type vehicle having an engine as claimed in claim 1.