JP2020133449A - engine - Google Patents

Abstract

To provide an engine which enables reduction of vibration sounds generated in a cylinder head with a simple structure.SOLUTION: An opening 46 which opens a cam chain chamber 53 to outdoor air is formed on a side wall 45 of a cylinder head 35, and a lid member 47 which closes the opening 46 from the outside is fitted in the opening 46. The lid member 47 includes a contact boss 47b extending from a lid body 47a which closes the opening 46 to a support wall 51. The contact boss 47b is fastened to the support wall 51 by a fastening member 75 while contacting with the support wall 51.SELECTED DRAWING: Figure 4

Description

The present invention has a support wall that rotatably supports the camshaft, and partitions a cam chain chamber for accommodating a cam chain connected to the cam shaft between the side wall facing the support wall and the support wall. The present invention relates to an engine provided with a cylinder head, the side wall of the cylinder head is formed with an opening for opening a cam chain chamber to the outside air, and a lid member for closing the opening is fitted in the opening.

Patent Document 1 discloses a cylinder head that is coupled to a cylinder block and has a side wall that partitions a cam chain chamber. On the side wall of the cylinder head, the first opening used for mounting the camshaft by opening the cam chain chamber to the outside air and the second opening used for mounting the rocker arm by opening the cam chain chamber to the outside air. An opening is formed. After the camshaft attachment work, the first opening is closed by the first lid member. After the rocker arm attachment work, the second opening is closed by the second lid member.

Japanese Patent No. 3966778

By the way, since the engine is required to be lighter in weight, the side wall of the cylinder head tends to be thinner. As the wall thickness becomes thinner, the rigidity of the side wall decreases, vibration is likely to occur, and vibration noise may be generated. The above-mentioned first opening and the second opening cause the rigidity of the side wall to be further reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine capable of reducing vibration noise generated in a cylinder head with a simple structure.

According to the first aspect of the present invention, a cam chain having a support wall that rotatably supports the camshaft and connected to the camshaft is provided between the side wall facing the support wall and the support wall. A cylinder head for partitioning a cam chain chamber to be accommodated is provided, and an opening for opening the cam chain chamber to the outside air is formed in the side wall of the cylinder head, and the opening is a lid member for closing the opening from the outside. In the engine into which the lid member is fitted, the lid member comprises a contact boss extending from the lid closing the opening toward the support wall, and the contact boss is fastened to the support wall in contact with the support wall. An engine that is fastened by a member is provided.

According to the second side surface, in addition to the configuration of the first side surface, a rocker arm shaft that swingably supports a rocker arm that swings according to the rotation of the camshaft is inserted into the support wall from the outside. The lid member has a retainer that extends from the lid body toward the support wall and contacts the end surface of the rocker arm shaft from the outside.

According to the third side surface, in addition to the configuration of the second side surface, the rocker arm shaft is connected to the intake valve and swings the rocker arm that causes the intake valve to open / close in response to the rotation of the camshaft. Includes an intake-side rocker arm shaft that supports the exhaust valve and an exhaust-side rocker arm shaft that swingably supports the rocker arm that is connected to the exhaust valve and causes the exhaust valve to open and close in response to rotation of the camshaft. The retainer comes into contact with the intake side rocker arm shaft and the exhaust side rocker arm shaft, respectively.

According to the fourth side surface, in addition to the configuration of any one of the first to third side surfaces, the contact boss projects at a first height from the abutting surface that hits the wall surface of the support wall, and the support wall. A support shaft pin that is rotatably inserted around the center of the shaft and a support shaft pin that is arranged at a position radially deviated from the support shaft pin and protrudes from the abutting surface at a second height that is smaller than the first height. It is provided with a knock pin to be inserted into a positioning hole formed on the wall surface.

According to the fifth side surface, in addition to the configuration of the fourth side surface, the fastening member is arranged coaxially with the support shaft pin, and the outer surface of the lid is centered toward the support wall with respect to the outer edge. It dents.

According to the sixth side surface, in addition to the configuration of the fifth side surface, the fastening member is located closer to the support wall side than the outer surface of the side wall.

According to the seventh side surface, in addition to the configuration of the sixth side surface, an O-ring that contacts the side wall on a cylindrical surface coaxial with the support shaft pin is mounted on the outer edge of the lid, and the support shaft pin is attached. In the axial direction of, the distance between the O-ring and the tip of the knock pin is set to be larger than the distance between the wall surface of the support wall and the outer surface of the side wall.

According to the eighth side surface, in addition to the configuration of any one of the first to sixth side surfaces, the engine is a sealing member sandwiched between the outer edge of the lid and the side wall in the axial direction of the support shaft pin. To be equipped.

According to the first side surface, since the lid member is fixed to the support wall having higher rigidity than the side wall, the vibration of the side wall is suppressed through the lid member. Therefore, with a simple structure, the vibration noise generated in the cylinder head is reduced.

According to the second side surface, since the lid member is provided with the rocker arm shaft retaining, the rocker arm shaft can be prevented from coming off without increasing the number of parts.

According to the third aspect, since the lid member is provided with a plurality of rocker arm shafts to prevent them from coming off, it is possible to prevent the rocker arm shafts from coming off without further increasing the number of parts.

According to the fourth side surface, when the support shaft pin is inserted into the support wall while ensuring a distance larger than the second height between the wall surface of the support wall and the abutting surface of the contact boss, the lid member becomes the support shaft. It can rotate around the axis of the pin. The knock pin can be positioned with respect to the positioning hole according to the rotation of the lid member. When the support shaft pin is further inserted, the knock pin can be inserted into the positioning hole. In this way, the lid member can be fixed to the support wall at the rotation position designated around the axis of the support shaft pin. Positioning is easily achieved.

According to the fifth side surface, since the fastening member is arranged in the recess on the outer surface of the lid body, the protrusion of the fastening member from the outer surface of the side wall can be reduced (avoided) when fastening the lid member.

According to the sixth side surface, when the lid member is fastened, the fastening member can be prevented from protruding from the outer surface of the side wall.

According to the seventh side surface, when the lid member rotates around the axis of the support shaft pin with the knock pin disengaged from the positioning hole, the O-ring separates from the opening of the side wall. Therefore, the contact friction of the O-ring does not affect the rotation of the lid member. Positioning of the lid member around the axis of the support shaft pin can be satisfactorily realized. When the knock pin is inserted into the positioning hole, the O-ring enters the side wall opening and seals between the outer edge of the lid and the side wall. The side wall openings are liquidtightly closed.

According to the eighth side surface, since the seal member restrains the side wall in the axial direction of the support shaft pin, the vibration suppressing effect can be further improved and the vibration noise can be further effectively reduced.

It is a side view which shows roughly the whole structure of the motorcycle which concerns on one Embodiment. It is a side view which shows roughly the whole structure of a motorcycle with the body cover removed. It is an enlarged right side view of a cylinder head. It is an enlarged perspective view of a cylinder head. It is the enlarged right side view of the cylinder head which broke the side wall. It is an enlarged sectional view of the engine which shows the structure of the valve operation mechanism schematicly. It is sectional drawing which follows the 7-7 line of FIG. It is an enlarged perspective view of a lid member. FIG. 7 is a conceptual diagram schematically showing a knock pin positioning operation corresponding to FIG. 7. It is sectional drawing which shows the lid member which corresponds to FIG. 7 and concerns on another specific example.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, the top, bottom, front, back, left, and right of the vehicle body shall be defined based on the viewpoint of the occupant who got on the motorcycle.

FIG. 1 schematically shows an overall image of a motorcycle which is a saddle-riding vehicle according to an embodiment of the present invention. The motorcycle 11 includes a vehicle body frame 12 and a vehicle body cover 13 mounted on the vehicle body frame 12. The vehicle body cover 13 has a front cowl 14 that covers the vehicle body frame 12 from the front, and a tank cover 17 that is continuous from the outer surface of the fuel tank 15 to the front and is connected to the occupant seat 16 behind the fuel tank 15. Fuel is stored in the fuel tank 15. When driving the motorcycle 11, the occupant straddles the occupant seat 16.

The body frame 12 includes a head pipe 18, a pair of left and right main frames 21 extending rearward from the head pipe 18 and having a pivot frame 19 at the rear lower end, and a position below the main frame 21 below the head pipe 18. It has a down frame 22 extending to the main frame 21 and integrated with the main frame 21, and left and right seat frames 23 extending rearward from the curved region 21a of the main frame 21 to form a truss structure. The occupant seat 16 is supported by the seat frame 23.

A front fork 24 is supported on the head pipe 18 so as to be steerable. The front wheel WF is rotatably supported on the front fork 24 around the axle 25. A steering handle 26 is coupled to the upper end of the front fork 24. The driver grips the left and right grips of the steering wheel 26 when driving the motorcycle 11.

A swing arm 28 is connected to the vehicle body frame 12 at the rear of the vehicle so as to swing up and down around the pivot 27. The rear wheel WR is rotatably supported around the axle 29 at the rear end of the swing arm 28. An engine 31 that generates a driving force transmitted to the rear wheel WR is mounted on the vehicle body frame 12 between the front wheel WF and the rear wheel WR. The engine 31 is connected to and supported by the down frame 22 and the main frame 21. The power of the engine 31 is transmitted to the rear wheel WR via the transmission device.

As shown in FIG. 2, the engine body of the engine 31 has engine hangers 32a and 32b connected to the main frame 21 at the upper and lower ends of the rear wall, and rotates the crankshaft around the rotation axis Rx to generate power. A crankcase 33 to output, a cylinder block 34 having a cylinder axis C connected to the front portion of the crankcase 33 from above and located in a vertical plane orthogonal to the rotation axis Rx and standing up against a horizontal plane, and a cylinder. A cylinder head 35 having an engine hanger 32c connected to the upper end of the block 34 and connected to the down frame 22 on the front wall and supporting the valve operating mechanism, and a cylinder head 35 connected to the upper end of the cylinder head 35. A head cover 36 for covering the upper valve mechanism is provided.

The cylinder head 35 has an intake device 38 that sprays fuel on the air purified by the air cleaner 37 to generate an air-fuel mixture and supplies the air-fuel mixture to the combustion chamber covered by the cylinder head 35, and is discharged from the combustion chamber. The exhaust gas after combustion is purified by the catalyst 39, and is connected to an exhaust device 41 that discharges the exhaust gas to the rear of the vehicle body while lowering the temperature of the exhaust gas. The exhaust device 41 includes an exhaust pipe 42 that passes under the crankcase 33, extends along the side of the rear wheel WR, and supports the catalyst 39 below the crankcase 33.

As shown in FIG. 3, a lid member 47 that closes the opening 46 is fitted from the outside into the side wall 45 (right side) that constitutes the outer wall of the cylinder head 35. The opening 46 has a circular contour. As shown in FIG. 4, the side wall 45 rotatably faces the support wall 51 that supports the intake side camshaft 48 and the exhaust side camshaft 49. The intake side camshaft 48 and the exhaust side camshaft 49 rotate around an axis parallel to the rotation axis of the crankshaft. Here, since the support wall 51 supports the intake side camshaft 48 and the exhaust side camshaft 49, the support wall 51 is formed to be thicker than the side wall 45 and has high rigidity.

As shown in FIGS. 4 and 5, the cylinder head 35 partitions a cam chain chamber 53 accommodating a cam chain 52 connected to two cam shafts 48 and 49 between the support wall 51 and the side wall 45. To do. The cam chain 52 includes a gear 54a fixed to the intake side camshaft 48 in the cam chain chamber 53, a gear 54b fixed to the exhaust side camshaft 49 in the cam chain chamber 53, and a crank in the cam chain chamber 53. It is wound around a gear (not shown) fixed to a shaft (not shown).

The intake side rocker arm shaft 55 and the exhaust side rocker arm shaft 56 are inserted into the support wall 51 of the cylinder head 35 from the outside. As shown in FIG. 6, the rocker arm 57 on the intake side rocker arm shaft 55 is swingably supported around the axis of the loacker arm shaft 55 on the intake side. The tip of the rocker arm 57 comes into contact with the upper end of the intake valve 58 at a position away from the axis of the intake side rocker arm shaft 55. The rocker arm 59 on the exhaust side is supported by the rocker arm shaft 56 so as to swing around the axis of the loacker arm shaft 56 on the exhaust side. The tip of the rocker arm 59 comes into contact with the upper end of the exhaust valve 61 at a position away from the axis of the exhaust side rocker arm shaft 56.

A cylinder 63 for accommodating the piston 62 is partitioned in the cylinder block 34. The cylinder 63 guides the linear reciprocating motion of the piston 62 along the cylinder axis C. A combustion chamber 64 is partitioned between the cylinder head 35 and the piston 62. In the combustion chamber 64, an intake passage 65 formed in the cylinder head 35 and connected to the air passage of the intake device 38 and an exhaust passage 66 formed in the cylinder head 35 and connected to the exhaust pipe 42 are opened. To do. The piston 62 is connected to the crankshaft by a connecting rod (not shown). The crankshaft rotates around the rotation axis Rx according to the linear reciprocating motion of the piston 62.

The intake valve 58 includes a valve head 58a that faces the combustion chamber 64 and opens and closes the opening of the intake passage 65, and a valve stem 58b that is coupled to the valve head 58a at the lower end and connected to the rocker arm 57 at the upper end. The valve stem 58b is supported by the cylinder head 35 so as to be displaced in the axial direction. A retainer 68 is attached to the upper end of the valve stem 58b by the action of a cotter 67. A string-wound spring 69 is sandwiched between the cylinder head 35 and the retainer 68 in a compressed state. The string-wound spring 69 exerts an elastic force to hold the valve head 58a in the closed position.

A slipper 57a for receiving the cam 48a of the intake side camshaft 48 is formed at the tip of the rocker arm 57. When the intake side camshaft 48 rotates, the cam 48a slides on the slipper 57a. The cam 48a presses the tip of the rocker arm 57 against the upper end of the valve stem 58b. The rocker arm 57 swings around the axis of the intake side rocker arm shaft 55 in response to the rotation of the intake side camshaft 48. The rocker arm 57 causes the intake valve 58 to open and close in response to the rotation of the intake side camshaft 48.

The exhaust valve 61 includes a valve head 61a that faces the combustion chamber 64 and opens and closes the opening of the exhaust passage 66, and a valve stem 61b that is coupled to the valve head 61a at the lower end and connected to the rocker arm 59 at the upper end. The valve stem 61b is supported by the cylinder head 35 so as to be displaced in the axial direction. A retainer 72 is attached to the upper end of the valve stem 61b by the action of a cotter 71. A string-wound spring 73 is sandwiched between the cylinder head 35 and the retainer 72 in a compressed state. The string-wound spring 73 exerts an elastic force that holds the valve head 61a in the closed position.

A slipper 59a for receiving the cam 49a of the exhaust side camshaft 49 is formed at the tip of the rocker arm 59. When the exhaust side camshaft 49 rotates, the cam 49a slides on the slipper 59a. The cam 49a presses the tip of the rocker arm 59 against the upper end of the valve stem 61b. The rocker arm 59 swings around the axis of the exhaust side rocker arm shaft 56 in response to the rotation of the exhaust side camshaft 49. The rocker arm 59 causes the exhaust valve 61 to open and close in response to the rotation of the exhaust side camshaft 49.

As shown in FIG. 7, the opening 46 formed in the side wall 45 of the cylinder head 36 opens the cam chain chamber 53 into the space of the outside air. The lid member 47 includes a contact boss 47b extending from the lid body 47a closing the opening 46 toward the support wall 51. The contact boss 47b hits the wall surface of the support wall 51 at the abutting surface 74 at the tip. The abutting surface 74 is formed on a flat surface that contacts the wall surface of the support wall 51. The contour of the lid 47a is formed in a circular shape to match the contour of the opening 46.

The contact boss 47b is fastened to the support wall 51 by a bolt (fastening member) 75 in a state of being in contact with the support wall 51. A mounting hole 76 is formed in the support wall 51 coaxially with the contour of the opening 46. The mounting holes 76 are formed at a first depth inward from the wall surface and surrounded by a cylindrical surface, and a second depth from the inner end of the insertion hole 76a, and have a smaller diameter than the insertion hole 76a. A screw hole 76b having a female screw 77 carved on the inner peripheral surface thereof is provided. A male screw 78 screwed into a female screw 77 of a screw hole 76b is engraved on the shaft 75a of the bolt 75. The outer surface of the lid 47a is recessed toward the support wall 51 on the center side with respect to the outer edge. The head 75b of the bolt 75 is located closer to the support wall 51 than the reference plane PL including the outer surface of the side wall 45.

As shown in FIG. 8, the contact boss 47b is arranged at a position radially deviated from the support shaft pin 79 and the support shaft pin 79 protruding from the abutting surface 74 at the first height Hf. It includes a knock pin 81 protruding from the abutting surface 74 at a second height Hs smaller than one height Hf. The support shaft pin 79 has an axial center coaxial with the contour of the lid 47a. The knock pin 81 has an axial center parallel to the axial center of the support shaft pin 79.

As shown in FIG. 7, the support shaft pin 79 is rotatably inserted into the insertion hole 76a of the support wall 51 around the axis. The bolt 75 is arranged coaxially with the support shaft pin 79 and penetrates the support shaft pin 79. The support shaft pin 79 can be composed of a sleeve that is coaxially fitted to the contour of the lid 47a at the tip of the contact boss 47b. The sleeve may be press-fitted into the tip of the contact boss 47b.

As shown in FIG. 5, a positioning hole 82 having a central axis parallel to the central axis of the mounting hole 76 is formed on the wall surface of the support wall 51. The positioning hole 82 is arranged inside the virtual cylindrical surface 83 set coaxially with the mounting hole 76 together with the intake side rocker arm shaft 55 and the exhaust side rocker arm shaft 56. The size of the virtual cylindrical surface 83 overlaps with the contour of the opening 46 at the maximum.

The positioning hole 82 partitions a cylindrical space that receives the knock pin 81. The distance Df between the central axis of the positioning hole 82 and the central axis of the mounting hole 76 is equal to the distance Ds between the axis of the support shaft pin 79 and the axis of the knock pin 81. The knock pin 81 is inserted into the positioning hole 82.

As shown in FIG. 8, an O-ring 84 is attached to the outer edge of the lid 47. The O-ring 84 continuously surrounds the outer circumference of the lid 47 without interruption. The O-ring 84 is formed from, for example, an elastic body made of resin. As shown in FIG. 7, the O-ring 84 contacts the side wall 45 on a cylindrical surface coaxial with the support shaft pin 79. In this way, the opening 46 is airtightly closed by the lid 47a. As shown in FIG. 9, the distance Lf between the O-ring 84 and the tip of the knock pin 81 is set to be larger than the distance Ls between the wall surface of the support wall 51 and the outer surface of the side wall 45 in the axial direction of the support shaft pin 79. To.

As shown in FIG. 4, the lid member 47 extends from the lid body 47a toward the support wall 51 and comes into contact with the end surface of the intake side rocker arm shaft 55 from the outside, and is supported by the first retaining 85a and the lid body 47a. It has a second retaining 85b that extends toward the wall 51 and comes into contact with the end surface of the exhaust side rocker arm shaft 56 from the outside. As shown in FIG. 8, the first retaining 85a is formed with a notch 86 that escapes the trajectory of the gear 54a of the intake side camshaft 48. Therefore, as shown in FIG. 5, the intake side rocker arm shaft 55 is arranged at a position as close to the intake side camshaft 48 as possible, while the intake side camshaft 48 is partially extended on the extension of the intake side rocker arm shaft 55. Even if the gear 54a interferes, the retaining mechanism can be secured by the first retaining 85a that crosses the cam chain chamber 53. Similarly, the second retaining 85b is formed with a notch 87 for escaping the trajectory of the gear 54b of the exhaust side camshaft 49. Therefore, as shown in FIG. 5, the exhaust side rocker arm shaft 56 is arranged at a position as close to the exhaust side camshaft 49 as possible, while the exhaust side camshaft 49 is partially extended on the extension of the exhaust side rocker arm shaft 56. Even if the gear 54b interferes, the stopper can be secured by the second retaining 85b that crosses the cam chain chamber 53.

Next, the operation of this embodiment will be described. The engine 31 includes a cylinder head 35 that partitions the cam chain chamber 53 between the support wall 51 and the side wall 45 facing the support wall 51. An opening 46 is formed in the side wall 45 of the cylinder head 35 to open the cam chain chamber 53 in the space of the outside air. The lid member 47 is fitted into the opening 46 from the outside. The lid member 47 includes a contact boss 47b extending from the lid body 47a closing the opening 46 toward the support wall 51. The contact boss 47b is fastened to the support wall 51 by a bolt 75 in a state of being in contact with the support wall 51. Since the lid member 47 is fixed to the support wall 51 having higher rigidity than the side wall 45, the vibration of the side wall 45 is suppressed via the lid member 47. Therefore, with a simple structure, the vibration noise generated by the cylinder head 35 is reduced.

In the engine 31 according to the present embodiment, the intake side rocker arm shaft 55 that swingably supports the rocker arm 57 is inserted into the support wall 51 from the outside, and the exhaust side rocker arm that swingably supports the rocker arm 59. The shaft 56 is inserted from the outside. The lid member 47 extends from the lid body 47a toward the support wall 51 and comes into contact with the end surface of the intake side rocker arm shaft 55 from the outside, and extends from the lid body 47a toward the support wall 51 and outside. It has a second retaining 85b that comes into contact with the end surface of the rocker arm shaft 56 on the exhaust side. In this way, since the lid member 47 is provided with the intake side rocker arm shaft 55 and the exhaust side rocker arm shaft 56 to prevent them from coming off 85a and 85b, respectively, the rocker arm shafts 55 and 56 can be prevented from coming off without increasing the number of parts. .. In particular, since the lid member 47 is provided with the rocker arm shafts 55 and 56 to prevent the rocker arm shafts 55 and 56 from coming off 85a and 85b, the rocker arm shafts 55 and 56 can be prevented from coming off without further increasing the number of parts.

In the engine 31 according to the present embodiment, the outer surface of the lid 47a is recessed toward the support wall 51 on the center side with respect to the outer edge. Then, the bolt 75 is arranged coaxially with the support shaft pin 79. Since the bolt 75 is arranged in the recess on the outer surface of the lid body 47a, the bolt 75 is prevented from protruding from the outer surface of the side wall 45 when the lid member 47 is fastened. Moreover, since the lid 47a only enters the empty space in the cam chain chamber 53 when forming the recess of the lid 47a, the distance between the side wall 45 and the support wall 51 is not increased, and the size of the engine 31 is increased. Be avoided. Since the bolt 75 is located closer to the support wall 51 than the reference plane PL including the outer surface of the side wall 45, the bolt 75 is prevented from protruding from the outer surface of the side wall 45 when the lid member 47 is fastened.

When the support shaft pin 79 is inserted into the insertion hole 76a of the support wall 51 while ensuring a distance larger than the second height of the knock pin 81 between the wall surface of the support wall 51 and the abutting surface 74 of the contact boss 47b, The lid member 47 can rotate around the axis of the support shaft pin 79. The knock pin 81 does not come into contact with the support wall 51. The knock pin 81 can be positioned with respect to the positioning hole 82 according to the rotation of the lid member 47. When the support shaft pin 79 is further inserted after the knock pin 81 is positioned, the knock pin 81 can be inserted into the positioning hole 82. In this way, the lid member 47 can be fixed to the support wall 51 at the rotation position designated around the axis of the support shaft pin 79. Positioning is easily achieved. Depending on the positioning, the first retaining 85a and the second retaining 85b can be abutted against the intake side rocker arm shaft 55 and the exhaust side rocker arm shaft 56, respectively.

In the present embodiment, the distance Lf between the O-ring 84 and the tip of the knock pin 81 is set larger than the distance between the wall surface of the support wall 51 and the outer surface of the side wall 45 in the axial direction of the support shaft pin 79. Therefore, when the lid member 47 rotates around the axis of the support shaft pin 79 with the knock pin 81 detached from the positioning hole 82, the O-ring 84 separates from the opening 46 of the side wall 45. The contact friction of the O-ring 84 does not affect the rotation of the lid member 47. Positioning of the lid member 47 around the axis of the support shaft pin 79 is well realized. When the knock pin 81 is inserted into the positioning hole 82, the O-ring 84 enters the opening 46 of the side wall 45 and seals between the outer edge of the lid 47a and the side wall 45. The opening 46 of the side wall 45 is airtightly closed.

As shown in FIG. 10, the lid member 47 may be equipped with a seal member 88 sandwiched between the outer edge of the lid 47a and the side wall 45 in the axial direction of the support shaft pin 79. Here, the lid 47a includes a flange 89 that extends outward from the opening 46 of the side wall 45 and overlaps the outer surface of the side wall 45. The flange 89 continues on the outer circumference of the lid 47a without interruption. The seal member 88 is formed from, for example, an elastic body made of resin. The seal member 88 is sandwiched between the flange 89 and the outer surface of the side wall 45. Since the seal member 88 restrains the side wall 45 in the axial direction of the support shaft pin 79, the vibration suppressing effect can be further improved and the vibration noise can be further effectively reduced. In addition, the lid member 47 is configured in the same manner as the lid member 47 described above.

31 ... engine, 35 ... cylinder head, 45 ... side wall (of cylinder head), 46 ... opening, 47 ... lid member, 47a ... lid, 47b ... contact boss, 48 ... camshaft (intake side camshaft), 49 ... camshaft (exhaust side camshaft), 51 ... support wall, 52 ... camchain, 53 ... camchain chamber, 55 ... rocker arm shaft (intake side rocker arm shaft), 56 ... rocker arm shaft (exhaust side rocker arm shaft) ), 57 ... (intake side) rocker arm, 58 ... intake valve, 59 ... (exhaust side) rocker arm, 61 ... exhaust valve, 74 ... (contact boss) abutting surface, 75 ... fastening member (bolt), 79 ... Support shaft pin, 81 ... Knock pin, 82 ... Positioning hole, 84 ... O ring, 85a ... Retainer (first retainer), 85b ... Retainer (second retainer), 88 ... Seal member, Hf ... ( 1st height (of the support shaft pin), Hs ... 2nd height (of the knock pin).

Claims (8)

A camshaft has a support wall (51) that rotatably supports the camshafts (48, 49) and is located between the side wall (45) facing the support wall (51) and the support wall (51). A cylinder head (35) for partitioning a cam chain chamber (53) for accommodating a cam chain (52) connected to (48, 49) is provided.
An opening (46) for opening the cam chain chamber (53) to the outside air is formed in the side wall (45) of the cylinder head (35).
In the engine (31) in which the lid member (47) that closes the opening (46) is fitted into the opening (46) from the outside.
The lid member (47) includes a contact boss (47b) extending from a lid (47a) that closes the opening (46) toward the support wall (51), and the contact boss (47b) is the contact boss (47b). An engine characterized in that it is fastened to the support wall (51) by a fastening member (75) in a state of being in contact with the support wall (51). In the engine according to claim 1, a rocker arm shaft that swingably supports a rocker arm (57, 59) that swings according to the rotation of the camshaft (48, 49) on the support wall (51). (55, 56) is inserted from the outside, and the lid member (47) extends from the lid body (47a) toward the support wall (51) and extends from the outside to the end surface of the rocker arm shaft (55, 56). An engine characterized by having retaining stoppers (85a, 85b) that come into contact with the engine. In the engine according to claim 2, the rocker arm shafts (55, 56) are
An intake side rocker arm shaft (55) that is connected to an intake valve (58) and swingably supports a rocker arm (57) that is connected to the intake valve (58) and causes an opening / closing operation of the intake valve (58) according to the rotation of the camshaft (48). )When,
The exhaust side rocker arm shaft (56) that swingably supports the rocker arm (59) that is connected to the exhaust valve (61) and causes the opening / closing operation of the exhaust valve (61) in response to the rotation of the camshaft (49). ) And
The engine is characterized in that the retaining (85a, 85b) comes into contact with the intake side rocker arm shaft (55) and the exhaust side rocker arm shaft (56), respectively. In the engine according to any one of claims 1 to 3, the contact boss (47b) projects at a first height (Hf) from the abutting surface (74) that hits the wall surface of the support wall (51). The support shaft pin (79), which is rotatably inserted into the support wall (51) around the axis, is arranged at a position radially deviated from the support shaft pin (79) to have the first height. It is characterized by including a knock pin (81) that protrudes from the abutting surface (74) at a second height (Hs) smaller than (Hf) and is inserted into a positioning hole (82) formed in the wall surface. Engine to do. In the engine according to claim 4, the fastening member (75) is arranged coaxially with the support shaft pin (79), and the outer surface of the lid (47a) is centered on the center side with respect to the outer edge. An engine characterized by denting toward 51). The engine according to claim 5, wherein the fastening member (75) is located closer to the support wall (51) than the outer surface of the side wall (45). In the engine according to claim 6, an O-ring (84) that contacts the side wall (45) on a cylindrical surface coaxial with the support shaft pin (79) is attached to the outer edge of the lid (47a). The distance (Lf) between the O-ring (84) and the tip of the knock pin (81) in the axial direction of the support shaft pin (79) is the distance (Lf) between the wall surface of the support wall (51) and the side wall (45). An engine characterized in that it is set larger than the distance (Ls) from the outer surface. In the engine according to any one of claims 1 to 6, a seal member (88) sandwiched between the outer edge of the lid (47a) and the side wall 45 in the axial direction of the support shaft pin (79). An engine characterized by being equipped with.