JP2015178817A - Internal combustion engine valve gear oil supply structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine valve gear oil supply mechanism in which rocker arm oil passages are provided in intake and exhaust rocker arms for supplying oil to slide contact portions between the rocker arms and intake and exhaust cams, respectively, and rocker shaft internal oil passages leading to these rocker arm oil passages are provided in intake and exhaust rocker shafts, respectively, capable of ensuring a supply quantity of oil to the rocker arms irrespectively of changes in the numbers of revolutions of the cam shafts.SOLUTION: A communication oil passage 164 bypassing intake and exhaust cam shafts 77 and 79 is provided in a cam shaft support portion 82 so as to lead to an oil supply passage 165, and intake and exhaust journal oil passages 166 and 167 guiding oil to intake and exhaust cam shaft bearing portions 82a and 82b, respectively and a branch oil passage 168 continuous to the communication passage 164 so as to guide the oil to an oil passage leading to a rocker shaft oil passage are provided in the cam shaft support portion 82.

Description

  In the present invention, an intake side camshaft having an intake side cam corresponding to an intake valve and an exhaust side camshaft having an exhaust side cam corresponding to an exhaust valve are rotatably supported by a cylinder head of an engine body. An intake side rocker arm interposed between the intake valve and the intake side cam is swingably supported by the supported intake side rocker shaft, and the exhaust valve and the exhaust valve are supported by the exhaust side rocker shaft supported by the cylinder head. An exhaust-side rocker arm interposed between the exhaust-side cams is swingably supported, and oil is provided to the intake side and the exhaust-side rocker arm at the sliding contact portion between the rocker arms and the intake-side and exhaust-side cams. Rocker arm side oil passages are provided, and the rocker shaft oil passages leading to these rocker arm side oil passages are provided. Serial relates to an oil supply mechanism for an internal combustion engine valve gear respectively provided on the intake side and the exhaust side rocker within the shaft.

  Rocker arm side oil passages for supplying oil to the sliding portions of the intake side and exhaust side rocker arms and the intake side and exhaust side cams are provided in the intake side and exhaust side rocker arms, respectively, so as to communicate with these rocker arm side oil passages. Thus, the oil is supplied to the oil passage in the rocker shaft formed in the intake side and the exhaust side rocker shaft through a communication passage that branches directly from the annular lubricating oil passage that lubricates the bearing portion of the camshaft. An oil supply structure for a valve operating apparatus for an internal combustion engine is known from Patent Document 1.

Japanese Patent No. 4220415

  By the way, in what was disclosed by the said patent document 1, oil flows in into a cam shaft from the small hole provided in the cam shaft from the cyclic | annular lubricating oil path which lubricates the bearing part of a cam shaft, and the oil is others. In such a configuration, the amount of oil consumed in the bearing portion increases as the rotational speed of the camshaft increases. As a result, depending on the number of revolutions of the internal combustion engine, it is difficult to evenly distribute and supply oil from the annular lubricating oil passage that lubricates the bearing portion to the oil passages in the rocker shaft in the intake side and exhaust side rocker shafts. There is a need to improve oil supply.

  The present invention has been made in view of such circumstances, and provides an oil supply structure for a valve operating apparatus for an internal combustion engine that can secure an oil supply amount to a rocker arm regardless of changes in the rotational speed of a camshaft. The purpose is to do.

  In order to achieve the above object, the present invention provides an intake-side camshaft having an intake-side cam corresponding to an intake valve and an exhaust-side camshaft having an exhaust-side cam corresponding to an exhaust valve, which can freely rotate on a cylinder head of an engine body. And an intake side rocker arm interposed between the intake valve and the intake side cam is swingably supported on an intake side rocker shaft supported by the cylinder head, and an exhaust side supported by the cylinder head An exhaust-side rocker arm interposed between the exhaust valve and the exhaust-side cam is swingably supported on the rocker shaft, and the intake-side and exhaust-side rocker arms are provided with the rocker arms, the intake-side, and the exhaust-side. Rocker arm side oil passages for supplying oil to the sliding contact portions with the cams are respectively provided, and these rocker arm side oil passages are passed through. In an oil supply structure for a valve operating apparatus for an internal combustion engine, in which an oil passage in a rocker shaft is provided in each of the intake side and the exhaust side rocker shaft, the intake side and the exhaust side camshaft are rotatably supported and The oil provided in the cylinder head is configured such that a communication oil path that bypasses the intake side and the exhaust side cam shaft guides oil from the cylinder body side of the engine body to a cam shaft support provided in the cylinder head. Oil is led to an intake side and an exhaust side camshaft bearing portion provided in the camshaft support portion so as to communicate with the supply path and rotatably support the intake side and the exhaust side camshaft. The shim is connected to the intake side and exhaust side journal oil passages and the rocker shaft oil passages. The camshaft support portion is provided with a branch oil passage connected to the communication oil passage in parallel with the intake side and the exhaust side journal oil passage so as to guide the oil to the oil passage side provided in the cylinder head. One feature.

  According to the present invention, in addition to the configuration of the first feature, the camshaft support portion includes a bearing wall provided integrally with the cylinder head, and the intake side and exhaust side camshaft bearing portions are connected to the bearing wall. A cam holder fixed to the bearing wall so as to form in cooperation with the cam holder; a part of the oil supply path; the communication oil path leading to the oil supply path; the intake side; A second feature is that the exhaust-side journal oil passage and a part of the branch oil passage are provided.

  According to the present invention, in addition to the configuration of the second feature, the cylinder is configured such that a pair of oil passages individually communicate with the oil passages in the rocker shaft respectively provided in the intake side and exhaust side rocker shafts. A third feature is that the branch oil passage is provided in the head, and is branched and provided in the camshaft support portion so as to be divided and communicated with the pair of oil passages.

  The fourth feature of the present invention is that, in addition to the configuration of the third feature, a branch portion of the branch oil passage is provided at a joint portion of the bearing wall and the cam holder.

  According to the present invention, in addition to any of the configurations of the second to fourth features, the cam holder is integrally formed with a portion that sandwiches the intake side and the exhaust side camshaft between the bearing walls. The communication oil passage is formed to extend linearly in a direction orthogonal to the arrangement direction of the intake side and the exhaust side camshaft, and the intake side and the exhaust side journal oil passage are formed as the intake side and the exhaust side. The intake camshaft sliding contact surface and the exhaust camshaft sliding contact surface formed on the cam holder so as to be in sliding contact with the respective side camshafts and the communication oil passage are connected to each other. 5 features.

  According to the present invention, in addition to the configuration of the fifth feature, grooves for opening the intake side and the exhaust side journal oil passages are formed on the intake side and the exhaust side camshaft sliding contact surfaces of the intake side and the exhaust side. A sixth feature is that the camshaft is formed so as to extend in the axial direction of the camshaft.

  According to the present invention, in addition to the configuration of the sixth feature, a plurality of one of the intake valve and the exhaust valve are disposed for one combustion chamber and are arranged radially with respect to the combustion chamber. The other of the intake valve and the exhaust valve is disposed along a plane orthogonal to the axis of the intake side and the exhaust side camshaft, and the intake side protruding from the camshaft support portion and the exhaust valve A driven member that constitutes a part of a timing transmission mechanism that transmits rotational power from the crankshaft is fixed to the shaft end of the exhaust side camshaft. The cam holder is formed so that one camshaft sliding contact surface disposed on one valve side is offset from the other camshaft sliding contact surface toward the timing transmission mechanism. The communication oil passage is provided in the cam holder so as to pass through a central portion in the width direction of the other camshaft sliding contact surface on a plan view including planes including axes of the intake side and the exhaust side camshaft. A seventh feature is that the groove formed on the camshaft sliding contact surface is formed longer on the timing transmission mechanism side than the groove formed on the other camshaft sliding contact surface. .

  Further, according to the present invention, in addition to any of the configurations of the first to seventh features, a pair of one of the intake valve and the exhaust valve is disposed for one combustion chamber and the combustion is performed. A pair of insertion holes for inserting and fixing a pair of rocker shafts corresponding to the one valve among the intake side and the exhaust side rocker shafts are arranged with respect to the central axis of the insertion holes. A pair of communication passages are provided in the cylinder head independently of each other so that the extension lines cross each other, and a pair of communication passages for guiding oil from the oil passage to the pair of insertion holes are provided in the cylinder head. The eighth feature is that

  According to the first aspect of the present invention, the rocker shaft internal oil passages communicating with the rocker arm side oil passages provided in the intake side and exhaust side rocker arms respectively communicate with the oil passage provided in the cylinder head so as to be in the intake side and exhaust side. Provided respectively in the rocker shaft, the connecting oil passage for guiding oil from the cylinder body side is provided in the camshaft support portion of the cylinder head, bypassing the intake side and exhaust side camshafts, and the intake side and exhaust side camshafts The intake and exhaust side journal oil passages that guide oil to the bearing and the branch oil passage that guides oil to the oil passage are connected in parallel to the connecting oil passage, so the communication passage branches off from the camshaft bearing Compared to the oil supply structure in which oil is supplied to the rocker arm side oil passage via It is possible to ensure the amount of oil supplied to the rocker arm side oil passage.

  According to the second feature of the present invention, a cam holder in which the camshaft support portion is configured in cooperation with a bearing wall provided integrally with the cylinder head includes a part of the oil supply path, the communication oil path, and the intake air. Side and exhaust side journal oil passages and a part of the branch oil passage are provided, so that the connecting oil passage is processed on the cam holder side which is smaller than the cylinder head and can be separated from the cylinder head and The processing of the oil passages can be facilitated by processing the connecting portions of the plurality of oil passages.

  According to the third aspect of the present invention, the branch oil passage branches so as to directly communicate with a pair of oil passages individually communicating with the oil passages in the rocker shaft of the intake side and exhaust side rocker shafts. The oil supply amount to the oil passage in the rocker shaft of the exhaust side rocker shaft can be balanced.

  According to the fourth aspect of the present invention, the branch oil passage is formed so as to branch at the joint portion between the bearing wall and the cam holder, thereby processing the branch portion of the branch oil passage from the joint surface of the bearing wall with the cam holder. This makes it easy to process a branched branch oil passage.

  According to the fifth aspect of the present invention, the connecting oil passage is perpendicular to the arrangement direction of the intake side and exhaust side camshafts in the cam holder integrally having a portion sandwiching the intake side and exhaust side camshafts between the bearing walls. The intake-side and exhaust-side journal oil passages are connected between the intake-side camshaft sliding contact surface and the exhaust-side camshaft sliding contact surface of the cam holder and the communication oil passage. As a result, the intake side and exhaust side journal oil passages can be shortened to reduce the number of processing steps.

  According to the sixth aspect of the present invention, the grooves for opening the intake-side and exhaust-side journal oil passages extend in the axial direction of the intake-side and exhaust-side camshafts so as to be in contact with the intake-side and exhaust-side camshaft sliding surfaces. As a result, the oil supplied from the intake side and exhaust side journal oil passages is diffused in the axial direction of the intake side and exhaust side camshafts, and between the intake side and exhaust side camshafts and the camshaft support. The lubricity can be improved.

  According to the seventh feature of the present invention, a plurality of one of the intake valve and the exhaust valve are arranged for one combustion chamber and are arranged radially with respect to the combustion chamber. When one camshaft sliding contact surface on one valve side is arranged offset to the timing transmission mechanism side with respect to the other camshaft sliding contact surface, the axes of the intake side and exhaust side camshafts are included. Even if the communication oil passage is arranged so as to pass through the center in the width direction of the other camshaft sliding contact surface on the projection onto the plane, the groove formed on one camshaft sliding contact surface is the other camshaft Since it is formed longer on the timing transmission mechanism side than the groove on the sliding surface, the camshaft has a larger load in the direction perpendicular to the axis at the shaft end of the camshaft by providing the driven member. Between support and camshaft Serial also effectively can supply the oil to the portion of the driven member closer, it is possible to ensure good lubrication.

  Further, according to the eighth feature of the present invention, one of the intake valve and the exhaust valve is disposed in a pair with respect to one combustion chamber and is radially disposed with respect to the combustion chamber. Based on the above, a pair of insertion holes for inserting and fixing a pair of rocker shafts corresponding to the radially arranged valves of the intake side and exhaust side rocker shafts are provided in the cylinder head in an arrangement crossing each other, and these insertion holes are inserted. A pair of mutually independent communication paths for guiding oil to the holes are provided in the cylinder head so as to communicate with the oil path, so that oil is supplied to the insertion holes without allowing the pair of insertion holes to communicate with each other. And the rigidity of the cylinder head can be secured by shortening the overall length of the insertion hole.

1 is a side view of a motorcycle. It is a principal part vertical side view of the internal combustion engine which notches and shows a part of engine body. It is a left side view of the upper part of the engine body. FIG. 4 is a plan view of a cylinder head taken along line 4-4 of FIG. It is sectional drawing which follows the 5-5 line of FIG. It is sectional drawing which follows the 6-6 line of FIG. FIG. 7 is a sectional view taken along line 7-7 in FIG. 3. FIG. 8 is a sectional view taken along line 8-8 in FIG. 3. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 4. It is the perspective view which looked at the left side principal part of the cylinder head from back diagonally upward. It is the 11-11 line sectional view of Drawing 4. FIG. 12 is a sectional view taken along line 12-12 of FIG. 4. FIG. 13 is a sectional view taken along line 13-13 of FIG. FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. FIG. 15 is a cross-sectional view taken along line 15-15 in FIG. 4. FIG. 16 is a cross-sectional view taken along line 16-16 in FIG. FIG. 17 is a cross-sectional view taken along line 17-17 in FIG. 13. It is the figure which looked at the 1st cam holder from the 18-18 line arrow direction of FIG.

  The embodiment of the present invention will be described with reference to FIGS. 1 to 18 attached herewith. First, in FIG. 1, a body frame F of a motorcycle supports a front fork 21 that pivotally supports a front wheel WF so as to be steerable. From the head pipe 22, a pair of left and right main frames 23 extending rearwardly downward from the head pipe 22, a pair of left and right hangers 24 hanging downward from the front part of the main frames 23, and from the rear part of the main frame 23 A pair of left and right pivot frames 25 that extend downward, a pair of left and right seat rails 27 that are supported by the upper ends of columns 26 that are erected at the rear of the main frame 23 and extend rearward, and the main frame 23 And a rear stay 28 connecting the rear portion and the rear portion of the seat rail 27.

  An engine main body 29 of the internal combustion engine E is supported on a rear portion of the main frame 23 in the vehicle body frame F, a lower portion of the hanger 24, and a lower portion of the pivot frame 25. Further, the front end portion of the swing arm 30 that pivotally supports the rear wheel WR driven by the power exerted by the internal combustion engine E at the rear end portion is supported by the pivot frame 25 so as to be swingable up and down. A link 31 and a rear cushion unit 32 are provided between the column 26 of the vehicle body frame F.

  A fuel tank 33 disposed above the engine body 29 is mounted on the main frame 23, and a riding seat 34 disposed behind the fuel tank 33 is supported by the seat rail 27. Further, a radiator 35 is disposed in front of the engine body 29, and the radiator 35 is supported by the vehicle body frame F and the engine body 29.

  A part of the internal combustion engine E and a part of the body frame F are covered with a body cover 37, and the body cover 37 extends from the front of the head pipe 22 to the rear part of the main frame 23. And a front cowl 38 that covers the upper part of the internal combustion engine E, a pair of left and right side cowls 39 that are connected to the rear sides of the front cowl 38 and cover the lower part of the internal combustion engine E, and a rear cowl 40 that covers the seat rail 27 and the rear stay 28. With.

  2 and 3, the engine main body 29 of the internal combustion engine E includes a crankcase 43 that rotatably supports a crankshaft 42 having an axis extending in the vehicle width direction, and a cylinder axis C slightly tilted rearward. A cylinder body 44 coupled to the front upper end of the crankcase 43, a cylinder head 45 coupled to the upper end of the cylinder body 44, and a head cover 46 coupled to the upper end of the cylinder head 45; Consists of a single cylinder.

  A mission case 47 extending rearward is connected to the crankcase 43. A transmission (not shown) for shifting the rotational power from the crankshaft 42 is accommodated in the transmission case 47, and the output shaft 48 of the transmission protrudes from the left side wall of the transmission case 47. . A driving sprocket 49 is fixed to the output shaft 48. As shown in FIG. 1, a driven sprocket 50 is fixed to the axle of the rear wheel WR. The driven sprocket 49 and the driven sprocket 50 are endless. The chain 51 is wound around.

  4 to 7 together, combustion between the cylinder body 44 and the cylinder head 45 faces the top of a piston (not shown) slidably fitted to the cylinder body 44. A chamber 52 is formed, and a front intake side wall 45 a of the cylinder head 45 is provided with a single intake port 53 that can communicate with the combustion chamber 52. A rear side wall 45 b of the cylinder head 45 is provided with the combustion chamber 52. A pair of exhaust ports 54 that can communicate with each other is provided. The cylinder head 45 also controls an intake valve 55 for switching communication / blocking between the combustion chamber 52 and the intake port 53 to control intake air to the combustion chamber 52 and exhaust gas from the combustion chamber 52. Accordingly, an exhaust valve 56 that switches between communication and blocking between the combustion chamber 52 and the exhaust port 54 is disposed so as to be openable and closable for each combustion chamber 52.

  On the rear side wall 45 b of the cylinder head 45, an exhaust side connection cylinder portion 58 constituting a part of the pair of exhaust ports 54 is integrally projected so as to protrude rearward. The upstream end of the exhaust pipe 59 that communicates is connected to the exhaust side connecting cylinder portion 58. The exhaust pipe 59 is bent from the rear side wall 45 b of the cylinder head 45 to the left side of the engine body 29 and extends forward of the engine body 29, and is bent downward from the front of the engine body 29 to be below the crankcase 43. The downstream end of the exhaust pipe 59 is connected to an exhaust muffler 60 disposed below the mission case 47.

  On the front side wall 45a of the cylinder head 45, an intake side connection cylinder portion 61 that constitutes a part of the intake port 53 is projected integrally so as to protrude forward, and the intake side connection cylinder The downstream end of the throttle body 62 communicating with the intake port 53 is connected to the portion 61. A frame trap 63 is attached to the throttle body 62 and is formed in a hemispherical shape bulging upward by a metal mesh, and covers the upstream end opening of the throttle body 62. The throttle body 62 including the frame trap 63 is attached to the throttle body 62. The upstream portion is accommodated in an intake chamber 64 (see FIG. 1) disposed below the fuel tank 33.

  A first fuel injection valve 65 is attached to the throttle body 62 outside the intake chamber 64, and a second fuel injection valve 66 that injects fuel from the frame trap 63 toward the throttle body 62 is a support frame 67. The second fuel injection valve 66 is disposed in the intake chamber 64.

  At least one of the pair of intake valves 55 and exhaust valves 56 is arranged radially with respect to one of the combustion chambers 52. In this embodiment, the pair of intake valves 55 is radially arranged. The pair of exhaust valves 56 is normally disposed along a plane perpendicular to the axis of the crankshaft 42.

  Referring to FIG. 5, the stems 55a of the pair of intake valves 55 are slidable on a guide cylinder 68 provided in the cylinder head 45 in a radial arrangement so as to be separated from each other as the distance from the combustion chamber 52 increases. The intake valve 55 is biased in the valve closing direction by a retainer 69 fitted to the stem end 55 b of the intake valve 55 and a valve spring 70 provided between the cylinder head 45.

  Focusing on FIG. 6, the stems 56 a of the pair of exhaust valves 56 are slidable on a guide cylinder 71 that is disposed along a plane perpendicular to the axis of the crankshaft 42 and embedded in the cylinder head 45. The exhaust valve 56 is biased in the valve closing direction by a retainer 72 fixed to the stem end 56 b of the exhaust valve 56 and a valve spring 73 provided between the cylinder head 45.

  A valve operating device 75 that opens and closes the intake valve 55 and the exhaust valve 56 has a pair of intake side cams 76 individually corresponding to the pair of intake valves 55 and is rotatably supported by the cylinder head 45. An intake side camshaft 77, an exhaust side camshaft 79 having a pair of exhaust side cams 78 individually corresponding to the pair of exhaust valves 56, and rotatably supported by the cylinder head 45, the intake valve 55, A pair of intake side rocker arms 80 interposed between the intake side cams 76 and a pair of exhaust side rocker arms 81 interposed between the exhaust valve 56 and the exhaust side cam 78 are provided.

  The intake side camshaft 77 has an axis parallel to the crankshaft 42 and is disposed so as to intersect with an axis extending upward from the stem 55a of the intake valve 55. The exhaust side camshaft 79 is The exhaust valve 56 has an axis parallel to the crankshaft 42 and the intake camshaft 77 and is arranged so as to intersect with an axial extension line above the stem 56a of the exhaust valve 56. In addition, the intake side camshaft 77 and the exhaust side camshaft 79 extending in parallel with each other are rotatably supported by first and second camshaft support portions 82 and 83 provided in the cylinder head 45.

  One end portion of the pair of intake side rocker arms 80 corresponds to each intake side rocker arm 80 individually, and the intake side camshaft 77 and the exhaust side camshaft 79 as viewed from the axial direction. A pair of intake-side rocker shafts 84 supported by the cylinder head 45 so as to be disposed between the exhaust-side camshafts 79 are swingably supported. While being individually associated with the side rocker arm 81, it is arranged between the intake side camshaft 77 and the exhaust side camshaft 79 as viewed from the axial direction of the intake side camshaft 77 and the exhaust side camshaft 79. A pair of exhaust-side rocker shafts 85 supported by the cylinder head 45 are supported so as to be swingable.

  The other end portion of the intake side rocker arm 80 has a cam slipper 80 a that is in sliding contact with the intake side cam 76, and is disposed between the stem end 55 b of the intake valve 55 and the intake side cam 76. Moreover, the outer periphery of the intake side cam 76 obliquely intersects with the axis of the intake side camshaft 77 based on the radial arrangement of the intake valves 55 with respect to the combustion chamber 52. The pair of intake-side rocker shafts 84 is also supported by the cylinder head 45 with an axis that obliquely intersects with a straight line parallel to the axis of the intake-side camshaft 77. The other end of the exhaust side rocker arm 81 has a cam slipper 81 a that is in sliding contact with the exhaust side cam 78 and is disposed between the stem end 56 b of the exhaust valve 56 and the exhaust side cam 78.

  Referring to FIG. 2, the rotational power from the crankshaft 42 is transmitted to the intake side camshaft 77 and the exhaust side camshaft 79 via a timing transmission mechanism 88. The transmission mechanism 88 is wound around a drive sprocket 89 provided on the crankshaft 42, a driven sprocket 90 as a driven wheel rotatably supported by the cylinder head 45, and the drive sprocket 89 and the driven sprocket 90. A cam chain 91 as an endless transmission band; driven gears 92 and 93 fixed to shaft ends of the intake-side camshaft 77 and the exhaust-side camshaft 79 protruding from the first camshaft support portion 82; Rotate with the driven sprocket 90 so as to rotate with the driven sprocket 90. And and a drive gear 94 meshing with the common to the driven gear 92 and 93 with integrally provided.

  In addition, the driven sprocket 90 and the drive gear 94 are disposed closer to the crankshaft 42 than a straight line L connecting the central axes of the intake side camshaft 77 and the exhaust side camshaft 79.

  The crankshaft 42 and the drive sprocket 89 rotate in the direction indicated by the arrow 95 in FIG. 2, and the driven sprocket 90 and the drive gear 94 rotate in the direction indicated by the arrow 96 in FIG. The pair of driven gears 92 and 93, that is, the intake side camshaft 77 and the exhaust side camshaft 79 rotate in the same cam rotation direction indicated by an arrow 97 in FIG.

  A slipper 98 is in contact with the outer periphery of the slack side of the cam chain 91 between the drive sprocket 89 and the driven sprocket 90, which is the side fed from the drive sprocket 89 to the driven sprocket 90. A tensioner 99 abutting from the opposite side of the cam chain 91 is attached to the cylinder body 44. Further, a cam chain guide 100 is brought into contact with the outer periphery of the tension side, which is the side pulled by the drive sprocket 89, of the cam chain 91 between the drive sprocket 89 and the driven sprocket 90.

  The slipper 98 is formed in an arc shape so that a convex curved surface is slidably contacted with the outer periphery of the cam chain 91 on the relaxation side, and one end of the slipper 98 on the crankshaft 42 side is connected to the crankcase 43 via the pivot 101. Is pivotally supported. The cam chain guide 100 is formed of a synthetic resin having appropriate rigidity and elasticity so as to form a substantially arcuate shape along the cam chain 91 side, and the cam chain guide 100 on the crankshaft 42 side is formed. The end is fixed to the crankcase 43 by a bolt 102. Further, an end portion of the cam chain guide 100 on the driven sprocket 90 side is brought into contact with a contact support portion 103 provided in the cylinder head 45.

  The crankcase 43, the cylinder body 44, and the cylinder head 45 in the engine body 29 include the pair of driven gears 92 and 93, the driven sprocket 90, and the drive that constitute a part of the timing transmission mechanism 88. A housing chamber 104 for housing the gear 94 and running the cam chain 91 is formed, and the slipper 98 and the cam chain guide 100 are also housed in the housing chamber 104.

  8 and 9, the first camshaft support portion 82 includes a first bearing wall 105 that forms a part of the inner wall of the storage chamber 104 and is formed integrally with the cylinder head 45, and the intake air. An intake side camshaft bearing portion 82 a that rotatably supports the side camshaft 77 and the exhaust side camshaft 79 and an exhaust side camshaft bearing portion 82 b are formed in cooperation with the first bearing wall 105. And a first cam holder 106 fixed to one bearing wall 105.

  Referring to FIGS. 10 and 11 together, the first bearing wall 105 is in sliding contact with at least a part of the outer periphery of the intake side camshaft 77 and the exhaust side camshaft 78, in this embodiment. The cylinder head 45 is provided with a pair of arcuate camshaft sliding support surfaces 107 and 108 to be supported, and the first cam holder 106 includes the intake side camshaft 77 and the exhaust side camshaft. Camshaft sliding contact surfaces 109 and 110 are formed which are in sliding contact with the remaining part of the outer periphery of 78.

  4 and 7, the intake valve 55 and the exhaust valve are connected to the cylinder head 45 on the cylinder body 44 side of the cam shaft sliding contact support surfaces 107 and 108 of the first bearing wall 105. The number of the mounting bosses 111, 112, 113, 114 is the same as the number of 56, so that the through bolts 115 for fastening the cylinder head 45 together with the cylinder body 44 to the crankcase 43 are inserted. Provided around the intake valve 55 and the exhaust valve 56.

  Moreover, since the intake valve 55 of the intake valve 55 and the exhaust valve 56 is radially disposed with respect to the combustion chamber 52, a pair of the mounting boss portions disposed outside the intake valve 55. In order to avoid interference with the intake valve 55, the distances 111 from the central axis of the intake-side rocker shaft 84 in the direction perpendicular to the axes of the intake-side and exhaust-side camshafts 77, 79 are set. The pair of mounting boss portions 113 and 114 disposed outside the exhaust valve 56 are disposed at positions larger than the distance L2 from the central axis of the exhaust rocker shaft 85. On the other hand, on the first bearing wall 105, the mounting boss portion 111 on the first bearing wall 105 side of the mounting boss portions 111 and 112 disposed outside the intake valve 55, and the exhaust valve 56. In order to allow the through bolt 115 to be inserted into the mounting boss portion 113 on the first bearing wall 105 side of the mounting boss portions 113 and 114 arranged on the outer side of the mounting boss portion 113, 114, Arc-shaped notches 116 and 117 are formed so as to cut out part of the contact support surfaces 107 and 108, but the mounting on the outside of the intake valve 55 and on the first bearing wall 105 side is performed. Of the pair of camshaft sliding contact support surfaces 107 and 108, in order to avoid the notch portion 116 that faces the boss portion 111 from becoming large and causing the rigidity of the first bearing wall 105 to decrease. One camshaft sliding contact support surface 107 disposed on the intake valve 55 side is offset to the storage chamber 104 side relative to the other camshaft sliding contact support surface 108 disposed on the exhaust valve 56 side. A first bearing wall 105 is formed for placement.

  The first cam holder 106 is formed to have an integrated shape bent corresponding to the shape of the first bearing wall 105, and the camshaft sliding contact support surface 107 and the camshaft on the intake valve 55 side. A pair of bolts 118 disposed on both sides of the sliding contact surface 110 and a pair of bolts 119 disposed on both sides of the camshaft sliding contact support surface 108 and the camshaft sliding contact surface 111 on the exhaust valve 56 side. Fixed to the first bearing wall 105.

  Referring to FIG. 8, the driven sprocket 90 and the drive gear 94 are arranged on the first bearing wall 105 such that the driven sprocket 90 is arranged on the first bearing wall 105 side of the drive gear 94. It is rotatably supported on a fixed support shaft 121 via a ball bearing 122.

  The support shaft 121 has a small-diameter cylindrical portion 121a whose one end is fitted and fixed to the first bearing wall 105 side, and a flange portion 121b projecting radially outward from the other end of the small-diameter cylindrical portion 121, A large-diameter cylindrical portion 121c whose one end is continuous with the outer periphery of the flange portion 121b is integrally formed to have a stepped cylindrical shape. On the other hand, the first bearing wall 105 is formed to have a larger diameter than the screw hole 123 so as to fit the bottomed screw hole 123 and one end of the small diameter cylindrical portion 121a of the support shaft 121. A support shaft fitting hole 124 and a spacer fitting hole 125 having a diameter larger than that of the support shaft fitting hole 124 are formed continuously in this order. In addition, the screw hole 123, the support shaft fitting hole 124, and the spacer fitting are formed in an outer wall 126 that forms a part of the storage chamber 104 between the cylinder head 45 and the first bearing wall 105. A fitting hole 127 corresponding to the hole 125 is provided, and the large-diameter cylindrical portion 121c of the support shaft 121 is fitted into the fitting hole 127, and the outer periphery of the large-diameter cylindrical portion 121c An annular seal member 128 that is in close contact with the inner periphery of the fitting hole 127 is attached.

  A bolt 129 that is screwed into the screw hole 123 is inserted into the small-diameter cylindrical portion 121a of the support shaft 121, and the enlarged-diameter head portion 129a of the bolt 129 is brought into contact with and engaged with the flange portion 112b. Until then, the support shaft 121 is fixed to the first bearing wall 105 by screwing the bolt 129 into the screw hole 123.

  An inner ring 122 a of the ball bearing 122 surrounds the small diameter cylindrical portion 121 a of the support shaft 121, and has a fitting cylinder portion 130 a that fits into the flange portion 121 b of the support shaft 121 and the spacer fitting hole 125. Thus, it is sandwiched between the spacer 130 and the first bearing wall 105.

  The first bearing wall 105 accommodates at least a part of the driven sprocket 90, in this embodiment, a part of the driven sprocket 90 on the driven gears 92 and 93 side, for example, on the head cover 46 side. A sprocket accommodating recess 131 formed in a bulging arc shape is formed. On the other hand, on the inner surface of the outer wall 126 of the cylinder head 45, a gear receiving recess 132 for receiving a part of the drive gear 94 is formed. The gear receiving recess 132 is formed by the pair of driven gears 92, 93. In correspondence with the arrangement shape of the drive gear 94, it is formed so as to have a V shape opened to the intake side and the exhaust side camshafts 77, 79 side. In addition, a protrusion 126 a having a shape corresponding to the gear receiving recess 132 is provided on the outer surface of the outer wall 126 corresponding to the gear receiving recess 132.

  Further, as shown in FIG. 11, the first bearing wall 105 is provided with a pair of through holes 133 that sandwich the driven sprocket 90 and the drive gear 94 from both sides below the sprocket housing recess 131.

  Referring to FIG. 12, the second camshaft support portion 83 includes the intake-side and A second bearing wall 135 that extends in a direction perpendicular to the axis of the exhaust camshafts 77 and 79 and is formed integrally with the cylinder head 45, and the intake and exhaust camshafts 77 and 79 are rotatable. It comprises a second cam holder 136 fixed to the second bearing wall 135 so that the intake side and exhaust side camshaft bearing portions 83a, 83b to be supported are formed in cooperation with the second bearing wall 135.

  The second bearing wall 135 has a pair of arcuate camshaft sliding contact support surfaces 137 and 138 that are slidably supported on a part of the outer periphery of the intake side and exhaust side camshafts 77 and 79. Cam shaft sliding surfaces 139 and 140 are formed on the cylinder head 45, and the second cam holder 136 is in sliding contact with a part of the outer periphery of the intake side and exhaust side cam shafts 77 and 79. .

  The second cam holder 136 is formed so as to have an integral shape corresponding to the shape of the second bearing wall 135, and the camshaft sliding contact support surface 137 and the camshaft sliding contact surface on the intake valve 55 side. A pair of bolts 141 disposed on both sides of the 139 and a pair of bolts 142 disposed on both sides of the camshaft sliding contact surface 140 and the camshaft sliding contact surface 140 on the exhaust valve 56 side. It is fixed to the bearing wall 135.

  A spark plug (not shown) is attached to the second bearing wall 135 at the portion surrounded by the pair of intake valves 55 and the pair of exhaust valves 56 so that the tip of the combustion chamber 52 faces the tip. A plug mounting hole 143 is provided, and the second cam holder 136 is provided with a circular opening 144 leading to the plug mounting hole 143.

  The second bearing wall 135 is provided with a pair of through holes 145 disposed on both sides of the plug mounting hole 143 in order to reduce the weight of the cylinder head 45.

  In FIG. 13, the pair of exhaust-side rocker shafts 85 is inserted and fixed in an insertion hole 146 provided in the cylinder head 45 with an axis parallel to the exhaust-side camshaft 79. The insertion hole 146 is perforated from the side wall of the cylinder head 45 opposite to the accommodation chamber 104 while closing the end portion on the accommodation chamber 104 side, and the opening end of the insertion hole 146 is formed. A plug 147 that closes liquid tightly is screwed into the cylinder head 45.

  As shown in FIG. 14, an arc-shaped locking recess 148 is formed at a predetermined position on the outer periphery of the exhaust side rocker shaft 85, and the bolt 149 is engaged with the locking recess 148 so that the bolt 149 is engaged with the locking recess 148. Screwed onto the cylinder head 45. As a result, the pair of exhaust-side rocker shafts 85 are inserted and fixed at predetermined positions in the common insertion hole 146, and the slit 150 that faces a part of the exhaust-side rocker shafts 85 is formed in the cylinder head. 45. One end of the exhaust side rocker arm 81 is swingably supported by the exhaust side rocker shaft 85 in the slit 150.

  In FIG. 15, the pair of intake side rocker shafts 84 are arranged separately on both sides of the second camshaft support portion 83, and the second camshaft support of the pair of intake side rocker shafts 84 is arranged. One intake-side rocker shaft 84 disposed between the portion 83 and the storage chamber 104 has one end opened to the sprocket storage recess 131 formed in the first bearing wall 105 facing the storage chamber 104 and the other. The other intake-side rocker shaft 84 of the pair of intake-side rocker shafts 84 is opposite to the housing chamber 104 and is inserted into and fixed to an insertion hole 151 provided in the cylinder head 45 so as to close the end. Then, it is inserted through the bottomed insertion hole 152 to be drilled from the side wall side of the cylinder head 45 and fixed. Moreover, the insertion holes 151 and 152 are provided independently of each other in the cylinder head 45 so that the extension lines of the central axes C1 and C2 of the insertion holes 151 and 152 intersect each other.

  The pair of intake-side rocker shafts 84 are bolts that are screwed into the cylinder head 45 in a state where the intake-side rocker shafts 84 are inserted into predetermined positions of the pair of insertion holes 151 and 152 individually corresponding to the intake-side rocker shafts 84. By engaging 153 with the intake side rocker shaft 84, the insertion holes 151 and 152 are inserted and fixed.

  A slit 153 that faces a part of the intake side rocker shaft 84 is formed in the cylinder head 45, and one end portion of the intake side rocker arm 80 can swing to the intake side rocker shaft 84 within the slit 153. Supported by

  By the way, the outer wall 126 of the cylinder head 45 has a through hole 155 that sandwiches the storage chamber 104 with the insertion hole 151, and the intake side rocker shaft 84 is inserted into the insertion hole 151 from the through hole 155. A plug 156 that liquid-tightly closes the through hole 155 is screwed to the outer wall 126, and a plug 157 that liquid-tightly closes the outer end opening of the insertion hole 152 is screwed to the cylinder head 45. Combined.

  Referring to FIG. 5, the pair of intake side rocker arms 80 includes a rocker arm for supplying oil to a sliding contact portion between the intake side rocker arms 80 and the intake side cam 76 of the intake side camshaft 77. A side oil passage 160 is provided, and the rocker arm side oil passage 160 opens to the upper portion of a passage portion 160a extending in the longitudinal direction of the intake side rocker arm 80 and an intermediate portion in the longitudinal direction of the intake side rocker arm 80, and the passage. It is formed so as to consist of an injection hole portion 160b communicating with the portion 160a.

  Referring to FIG. 6, the pair of exhaust side rocker arms 81 includes a rocker arm for supplying oil to a sliding contact portion between the exhaust side rocker arms 81 and the exhaust side cam 78 of the exhaust side camshaft 79. A side oil passage 161 is provided, and the rocker arm side oil passage 161 opens to an upper portion of a passage portion 161 a extending in the longitudinal direction of the exhaust side rocker arm 81 and a middle portion in the longitudinal direction of the exhaust side rocker arm 81. It is formed so as to be composed of an injection hole portion 161b communicating with the portion 161a.

  Each of the pair of intake side rocker shafts 84 is provided with a rocker shaft internal oil passage 162 communicating with the passage portion 160a in the rocker arm side oil passage 160 of the intake side rocker arm 80 individually corresponding to the intake side rocker shaft 84. The pair of exhaust side rocker shafts 85 have rocker shaft internal oil passages 163 communicating with the passage portions 161a in the rocker arm side oil passages 161 of the exhaust side rocker arms 81 individually corresponding to the exhaust side rocker shafts 85, respectively. Provided.

  Referring also to FIG. 16, the first camshaft support 82 provided on the cylinder head 45 by rotatably supporting the intake side and exhaust side camshafts 77 and 79 includes the intake side and the exhaust side camshafts 77 and 79. A communication oil passage 164 that bypasses the exhaust side camshafts 77 and 79 is provided so as to lead to an oil supply passage 165 provided in the cylinder head 45 so as to guide oil from the cylinder body 44 side. The intake-side and exhaust-side journal oil passages 166, 167 for guiding oil to the intake-side and exhaust-side camshaft bearing portions 82a, 82b formed in one camshaft support portion 82, and the rocker shaft inner oil passages 162, 163 The oil is guided to the oil passages 169 and 170 provided in the cylinder head 45 so as to communicate with each other. A branch oil passage 168 air side and communicating with the communication oil passage 164 in parallel with the exhaust-side journal oil path 166 and 167, provided on the first cam shaft support portion 82.

  In addition, the first camshaft support portion 82 is formed in cooperation with the first bearing wall 105 provided in the cylinder head 45, and a part of the oil supply passage 165 and the oil The communication oil passage 164 leading to the supply passage 165, the intake side and exhaust side journal oil passages 166, 167, and a part of the branch oil passage 168 are provided.

  Meanwhile, the pair of oil passages 169 and 170 communicate with the cylinder head 45 so as to individually communicate with the rocker shaft internal oil passages 162 and 163 provided in the intake side and exhaust side rocker shafts 84 and 85, respectively. The branched oil passage 168 is provided in the first camshaft support 82 so as to be branched and communicated with the pair of oil passages 169 and 170.

  In FIG. 17, the branch oil passage 168 includes a common oil passage portion 168a communicating with the communication oil passage 164, one end portion passing through the common oil passage portion 168a, and the other end portions individually connected to the oil passages 169 and 170. The individual oil passage portions 168b and 168c to be communicated with each other, and the individual oil passage portions 168b and 168c formed in the first bearing wall 105 in the first camshaft support portion 82 are the first oil passage portions 168b and 168c. The common oil passage portion 168 a formed on the first cam holder 106 in the camshaft support portion 82 communicates with the joint portion of the first bearing wall 105 and the first cam holder 106. That is, the branch portion 168 d of the branch oil passage 168 is provided at the joint between the first bearing wall 105 and the first cam holder 106.

  Referring also to FIG. 18, the communication oil passage 164 is formed in the first cam holder 106 so as to extend linearly in a direction orthogonal to the arrangement direction of the intake side and exhaust side camshafts 77 and 79, The intake-side and exhaust-side camshafts formed in the first cam holder 106 so that the intake-side and exhaust-side journal oil passages 166, 167 are in sliding contact with the intake-side and exhaust-side camshafts 77, 79, respectively. It is formed so as to connect the topmost portions of the sliding contact surfaces 109 and 110 and the communication oil passage 164.

  Further, grooves 171 and 172 for opening the intake side and exhaust side journal oil passages 166 and 169 are formed on the intake side and exhaust side camshaft sliding contact surfaces 109 and 110 of the first cam holder 106, respectively. The exhaust camshafts 77 and 79 are formed so as to extend in the axial direction.

  Of the intake side and exhaust side camshaft sliding surfaces 109, 110, the intake side camshaft sliding surface 109 disposed on the intake valve 55 side that is radially disposed with respect to the combustion chamber 52 is connected to the exhaust side camshaft. A first cam holder 106 is formed so as to be offset from the sliding contact surface 110 toward the timing transmission mechanism 88 and the storage chamber 104, and the communication oil passage 164 has the intake side and the exhaust side. The first cam holder 106 is provided so as to pass through the central portion in the width direction of the exhaust side camshaft sliding contact surface 110 on a projected view including the axis of the camshafts 77 and 79.

  The groove 171 formed on the intake side camshaft sliding contact surface 109 corresponding to the arrangement of the communication oil passage 164 is more than the groove 172 formed on the exhaust side camshaft sliding contact surface 110. , It is formed longer on the storage chamber 104 side.

  The oil passages 169 and 170 are provided in the cylinder head 45 in parallel with the intake side and exhaust side camshafts 77 and 79 so as to be disposed between the intake valve 55 and the exhaust valve 56. The oil passage 169 is disposed below a pair of insertion holes 151 and 152 provided in the cylinder head 45 so as to pass through the intake side rocker shaft 84, and the oil passage 170 is connected to the exhaust side rocker shaft. 85 is inserted below the insertion hole 146 provided in the cylinder head 45.

  The oil passages 169 disposed below a pair of insertion holes 151 and 152 provided in the cylinder head 45 so as to be inserted through the intake side rocker shaft 84 extend independently in the vertical direction. Oil connected to the pair of insertion holes 151 and 152 via a pair of communication paths 173 and 174 provided in the cylinder head 45, and the oil guided into the insertion holes 151 and 152 via the oil passage 162 in the rocker shaft. Guided to the rocker arm side oil passage 160.

  The oil passage 170 disposed below the insertion hole 146 provided in the cylinder head 45 so as to pass through the exhaust-side rocker shaft 85 extends in a pair so as to extend vertically. The oil communicated with the insertion hole 146 through the communication path 175 and guided into the insertion hole 146 is guided to the rocker arm side oil path 161 through the rocker shaft oil path 163.

  By the way, the rocker arms provided on the intake side and the exhaust side rocker arms 80 and 81 respectively at the sliding contact portions between the intake side and the exhaust side rocker arms 80 and 81 and the intake side and the exhaust side cams 76 and 78. Oil is supplied from the side oil passages 160 and 161, and the oil supply direction from the rocker arm side oil passage 160 to the sliding contact portions of the intake side cam 76 and the intake side rocker arm 80 among the sliding contact portions thereof. 5 is the same direction as the cam rotation direction 97 as shown in FIG. 5, the oil supply direction from the rocker arm side oil passage 161 to the sliding contact portion of the exhaust side cam 78 and the exhaust side rocker arm 81 is shown in FIG. 6, the direction opposite to the cam rotation direction 97 is such that a part of the oil supplied from the rocker arm side oil passage 161 is in the exhaust side cam 78. Will be repelled by the rolling oil supply amount is likely to be insufficient to sliding contact portion of the exhaust-side cam 78 and the exhaust-side rocker arm 81. Therefore, oil is supplied from the auxiliary oil supply means 176 in the same direction as the cam rotation direction 97 to the sliding contact portions of the exhaust side cam 78 and the exhaust side rocker arm 81.

  The auxiliary oil supply means 176 extends in parallel with the axis of the intake and exhaust side camshafts 77 and 79 and communicates with an auxiliary oil supply passage 177 provided in the cylinder head 45 and the auxiliary oil supply passage 177. The exhaust valve is provided with a pair of oil injection holes 178 provided in the cylinder head 45, and is disposed along a plane orthogonal to the axis of the intake side and the exhaust side camshafts 77 and 79. The cylinder head 45 is disposed on the 56 side.

  The auxiliary oil supply path 177 leads to the oil supply path 165 provided in the cylinder head 45 so as to guide oil from the cylinder body 44 side, and the communication on the downstream side of the oil supply path 165 is performed. A pair of the oil passages 169 and 170 branched from the oil passage 164 and the auxiliary oil supply passage 177 extend in parallel with each other and are provided in the cylinder head 45.

  In addition, one of the pair of oil passages 169 and 170 is disposed at a position sandwiching the exhaust valve 56 between the auxiliary oil supply passage 177 and between the intake valve 55 and the exhaust valve 56. Placed in.

  Referring to FIG. 12, the cylinder head 45 is provided with a second camshaft support portion 83 that rotatably supports an intermediate portion between the intake side and the exhaust side camshafts 77 and 79. The camshaft support 83 and the camshaft lubrication passage 179 branched from the oil passage 169 corresponding to the intake valve 55 side of the pair of oil passages 169, 170 are the intake-side camshaft 77 and the second cam. The cylinder head 45 is provided so as to supply oil between the shaft support portion 83 and the camshaft lubrication passage 179 extends from the oil passage 169 to below the intake side camshaft 77. A passage portion 179a extending in the lateral direction, and an intake side camshaft of the second camshaft support portion 83 extending upward from the passage portion 179a. Comprising a passage 179b leading to the shift bearing portion 83a.

  A camshaft lubrication passage 180 branched from the auxiliary oil supply passage 177 is provided in the cylinder head 45 so as to supply oil between the exhaust camshaft 79 and the second camshaft support 83. The camshaft lubrication passage 180 is formed so as to extend obliquely upward from the auxiliary oil supply passage 177 and reach the exhaust camshaft bearing portion 83b of the second camshaft support portion 83.

  The pair of oil passages 169 and 170 and the auxiliary oil supply passage 177 are provided in the cylinder head 45 so as to be formed by processing from the same one side surface 45c of the cylinder head 45. The one side surface 45c accommodates a timing transmission mechanism 88 that transmits power from the crankshaft 42 to the intake side and exhaust side camshafts 77, 79 of all side surfaces of the cylinder head 45, and stores the engine body. In this embodiment, the storage chamber 104 is formed on the right side of the engine main body 29, so that the one side surface 45c is the right side surface. That is, the oil passages 169 and 170 and the auxiliary oil supply passage 177 are perforated from the side surface 45c which is the right side surface of the cylinder head 45, and the oil passages 169 and 170 and the auxiliary oil supply passage 177 at the side surface 45c are drilled. The open end of each is closed liquid-tightly by plugs 181, 182 and 183.

  Next, the operation of this embodiment will be described. Intake and exhaust side camshafts 77 and 79 individually corresponding to the intake valve 55 and the exhaust valve 56 are rotatably supported by the cylinder head 45, and A cam chain 91 that transmits rotational power from the crankshaft 42 is wound around a driven sprocket 90 that is rotatably supported, and a pair of shafts provided on the shaft ends of the intake side and exhaust side camshafts 77 and 79, respectively. A drive gear 94 that meshes in common with the driven gears 92 and 93 is provided coaxially with the driven sprocket 90, and the driven sprocket 90 and the drive gear 94 are center axes of the intake side and exhaust side camshafts 77 and 79. The pair of driven gears are disposed on the crankshaft 42 side of the straight line L connecting them 2 and 93, a first bearing wall that accommodates the driven sprocket 90 and the drive gear 94 and constitutes a part of the inner wall of the accommodating chamber 104 formed in the engine body 29 so that the cam chain 91 travels. 105 is provided on the cylinder head 45 so as to have a pair of camshaft sliding contact support surfaces 107 and 108 which are in sliding contact with and support at least a part of the outer periphery of the intake side and exhaust side camshafts 77 and 79. Since the sprocket accommodating recess 131 for accommodating at least a part of the sprocket 90 disposed on the first bearing wall 105 side with respect to the drive gear 94 is formed in the first bearing wall 105, the intake valve 55 and the exhaust gas are exhausted. At least one of the valves 56 is arranged radially with respect to the combustion chamber 52, and the intake side and exhaust side camshaft 7 , 79 while suppressing an increase in the width of the cylinder head 45 in the direction along the axis, the distance between the intake and exhaust side camshafts 77, 79 can be shortened, and the cylinder head 45 can be reduced in size. be able to.

  The intake valve 55, which is one of the intake valve 55 and the exhaust valve 56, is radially arranged, and the exhaust valve 56 is along a plane orthogonal to the axis of the intake side and the exhaust side camshafts 77 and 79. Therefore, it is possible to adopt a normal drive system as it is on the exhaust valve 56 side, and to complicate the valve drive structure by the radial arrangement of at least one of the intake valve 55 and the exhaust valve 56. The manufacturing cost can be reduced only on the valve 55 side.

  Further, the cylinder head 45 has the same number of mounting bosses 111, 112, 113, 114 as the number of the intake valves 55 and the exhaust valves 56, and through bolts 115 for fastening the cylinder head 45 to the crankcase 43. Is inserted around the intake valve 55 and the exhaust valve 56, and the first bearing wall 105 is disposed on the intake valve 55 side of the pair of camshaft sliding support surfaces 107 and 108. Since one camshaft sliding contact support surface 107 is disposed so as to be offset from the other camshaft sliding contact support surface 108 toward the storage chamber 104, the depth of the sprocket storage recess 131 is increased. By reducing the depth on the exhaust valve 56 side, which is not in a radial arrangement, the number of processing steps at the time of processing formation can be reduced.

  Further, a first cam holder 106 fixed to the first bearing wall 105 so as to sandwich the intake side and exhaust side camshafts 77 and 79 between the first bearing wall 105 includes the first bearing wall. Since the first bearing wall 105 has a bent shape, the cam holder is provided separately on the intake side and the exhaust side, since the first bearing wall 105 has a bent shape. The cost can be reduced without increasing the number of parts.

  A gear housing recess 132 for housing a part of the drive gear 94 is formed on the inner surface of the outer wall 126 that forms a part of the housing chamber 104 between the cylinder head 45 and the first bearing wall 105. In addition, since a protrusion 126 a having a shape corresponding to the gear receiving recess 132 is provided on the outer surface of the outer wall 126, a gear housing that houses a part of the drive gear 94 in the outer wall 126 of the cylinder head 45. Only the portion corresponding to the recess 132 protrudes in the axial direction of the intake side and exhaust side camshafts 77 and 79, so that the entire cylinder head 45 can be prevented from being enlarged.

  The gear receiving recess 132 has a V-shape that is open to the intake side and the exhaust side camshafts 77 and 79 corresponding to the arrangement of the pair of driven gears 92 and 93 and the drive gear 94. Therefore, when the cylinder head 45 of the drive gear 94 and the driven sprocket 90 is assembled, the drive gear 94 is dropped into the gear receiving recess 132, so that approximate positioning is possible. Improvements can be made.

  Further, a stem end 55b of an intake valve 55 which is one of the intake valve 55 and the exhaust valve 56, an intake side cam 76 of the intake side camshaft 77 which is one of the intake side and the exhaust side camshafts 77 and 79, Between the intake side and the exhaust side camshafts 77, 79, and an intake side rocker arm that is swingably supported by an intake side rocker shaft 84 that is inserted into and fixed to the cylinder head 45. 80, an insertion hole 151 through which the intake side rocker shaft 84 is inserted is provided in the cylinder head 45 with one end opened in the sprocket housing recess 131, and the housing chamber 104 is formed between the insertion hole 151 and A through-hole 155 sandwiched between the intake-side rocker shaft 84 and the through-hole 151 can be inserted into the through-hole 151. Therefore, when the intake side rocker shaft 84 inserted through the through hole 155 is inserted into one end of the insertion hole 151, the position of one end of the insertion hole 151 can be easily confirmed. Assembling property to the cylinder head 45 can be improved.

  Further, since the first bearing wall 105 is provided with a pair of through holes 133 that sandwich the driven sprocket 90 and the drive gear 94 from both sides below the sprocket housing recess 131, the crankshaft 42 and the driven sprocket 90 While a load acts on the cylinder head 45 from the driven sprocket 90 and the drive gear 94 side in the direction connecting the axes, the through hole 133 is disposed at a position avoiding the load acting direction, thereby avoiding a decrease in rigidity. Thus, the weight of the cylinder head 45 can be reduced.

  A rocker arm side oil passage 160 for supplying oil to the intake side and the exhaust side rocker arms 80, 81 to the sliding contact portions between the rocker arms 80, 81 and the intake side cam 76 and the exhaust side cam 78. 161, and rocker shaft inner oil passages 162 and 163 communicating with the rocker arm side oil passages 160 and 161, respectively, are provided in the intake side and the exhaust side rocker shafts 84 and 85, respectively. The exhaust oil camshafts 77 and 79 are rotatably supported by a first camshaft support portion 82 provided in the cylinder head 45 to communicate oil that bypasses the intake and exhaust camshafts 77 and 79. A passage 164 is provided in the cylinder head 45 so as to guide oil from the cylinder body 44 side. And an intake side formed in the first camshaft support 82 so as to rotatably support the intake side and the exhaust side camshafts 77 and 79. An oil passage 169 provided in the cylinder head 45 so as to communicate with the intake-side and exhaust-side journal oil passages 166, 167 leading the oil to the exhaust-side camshaft bearing portions 82a, 82b and the rocker shaft inner oil passages 162, 163. , 170, a branch oil passage 168 connected to the communication oil passage 164 in parallel with the intake side and exhaust side journal oil passages 166, 167 so as to guide oil to the side of the first camshaft support portion 82. Therefore, oil is supplied to the rocker arm side oil passage through the communication passage branched from the camshaft bearing. Compared to the oil supply structure so, it is possible to secure the amount of oil supplied to the rocker arm side oil passage 160 and 161 regardless of the rotational speed of the intake side and the exhaust side cam shaft 77, 79.

  Further, the first camshaft support portion 82 is connected to the first bearing wall 105 provided integrally with the cylinder head 45, and the intake side and exhaust side camshaft bearing portions 82a and 82b are connected to the first bearing wall. 105, and a first cam holder 106 fixed to the first bearing wall 105 so as to be formed in cooperation with the first bearing wall 105. The first cam holder 106 includes a part of the oil supply path 165 and the oil. Since the communication oil passage 164 communicating with the supply passage 165, the intake side and exhaust side journal oil passages 166, 167, and a part of the branch oil passage 168 are provided, the cylinder passage 45 is smaller than the cylinder head 45 and has a cylinder. On the side of the first cam holder 106 that can be separated from the head 45, the processing of the connecting oil passage 164 and the contact of the plurality of oil passages 166 to 168 with the connecting oil passage 164 are performed. So as to perform the machining of parts, it is possible to facilitate the working of the oil passage.

  A pair of oil passages 169 and 170 are provided in the cylinder head 45 so as to individually communicate with the oil passages 162 and 163 in the rocker shaft provided in the intake side and exhaust side rocker shafts 84 and 85, respectively. The branch oil passage 168 is branched into the pair of oil passages 169, 170 so as to communicate with each other, and is provided in the first camshaft support portion 82. The exhaust side rocker shafts 84 and 85 are branched so as to directly communicate with a pair of oil passages 169 and 170 that individually communicate with the oil passages 162 and 163 in the rocker shaft. The oil supply amount to the rocker shaft oil passages 162 and 163 can be balanced.

  Further, since the branch portion 168d of the branch oil passage 168 is provided at the joint portion between the first bearing wall 105 and the first cam holder 106, the joint surface of the first bearing wall 105 with the first cam holder 106 is provided. Therefore, the branch passage portion 168d of the branch oil passage 168 can be processed, and the branch branch oil passage 168 can be easily processed.

  The first cam holder 106 is formed so as to integrally have a portion sandwiching the intake side and exhaust side camshafts 77, 79 between the first bearing wall 105, and the communication oil passage 164 is formed. The intake side and the exhaust side camshafts 77 and 79 are formed to extend linearly in a direction orthogonal to the arrangement direction of the exhaust side camshafts 77 and 79, and the intake side and the exhaust side journal oil passages 166 and 167 are formed on the intake side and the exhaust side. The uppermost portion of the intake side camshaft sliding contact surface 109 and the exhaust side camshaft sliding contact surface 110 formed on the first cam holder 106 so as to be in sliding contact with the camshafts 77 and 79 and the communication oil passage 164, respectively. Since they are formed so as to be connected, the intake side and exhaust side journal oil passages 166, 167 can be shortened to reduce the number of processing steps.

  Further, grooves 171 and 172 for opening the intake side and exhaust side journal oil passages 166 and 167 are formed on the intake side and exhaust side camshaft sliding contact surfaces 109 and 110, respectively. 79, the oil supplied from the intake-side and exhaust-side journal oil passages 166, 167 is diffused in the axial direction of the intake-side and exhaust-side camshafts 77, 79, so that the intake air The lubricity between the side and exhaust side camshafts 77 and 79 and the first camshaft support portion 82 can be improved.

  Incidentally, the intake valve 55 is arranged radially with respect to the combustion chamber 52, and the exhaust valve 56 is arranged along a plane orthogonal to the axis of the intake side and the exhaust side camshafts 77, 79, and the first A driven gear that constitutes a part of a timing transmission mechanism 88 that transmits rotational power from the crankshaft 42 to the shaft ends of the intake side and exhaust side camshafts 77 and 79 protruding from one camshaft support portion 82. 92 and 93 are fixed, and one of the intake side and the exhaust side camshaft sliding contact surfaces 109 and 110 is disposed on the intake valve 55 side with one camshaft sliding contact surface 109 as the other camshaft sliding contact surface. The first cam holder 106 is formed so as to be offset from the timing transmission mechanism 88 side than 110, and the one camshaft sliding contact surface 1 is formed. 9 is formed longer on the timing transmission mechanism 88 side than the groove 72 formed on the other camshaft sliding contact surface 110, so that the intake side and exhaust side camshafts are formed. The driven gear 92 is provided even if the communication oil passage 164 is disposed so as to pass through the center portion in the width direction of the other camshaft sliding contact surface 110 on the projection view including the axes 77 and 79. As a result, although the load in the direction orthogonal to the axis is larger at the shaft end of the intake camshaft 77, the intake camshaft 77 has a portion near the driven gear 92 between the first camshaft support portion 82 and the intake camshaft 77. Also, oil can be supplied effectively, and a good lubrication state can be ensured.

  Further, a pair of insertion holes 151 and 152 for inserting and fixing a pair of intake side rocker shafts 84 corresponding to the radially arranged intake valves 55 of the intake side and exhaust side rocker shafts 84 and 85 are inserted into these insertion holes. The extension lines of the central axes C1 and C2 of the 151 and 152 are provided independently of each other in the cylinder head 45 so as to intersect with each other, and oil is supplied from the oil passages 169 and 170 to the pair of insertion holes 151 and 152. Since a pair of communication passages 173 and 174 leading to the cylinder head 45 are provided in the cylinder head 45 independently of each other, oil is supplied to the insertion holes 151 and 152 without causing the pair of insertion holes 151 and 152 to communicate with each other. This makes it possible to shorten the overall length of the insertion holes 151 and 152 and ensure the rigidity of the cylinder head 45.

  The oil supply direction from the rocker arm side oil passages 160 and 161 in the sliding contact portions of the intake side and exhaust side cams 76 and 78 and the intake side and exhaust side rocker arms 80 and 81 is opposite to the cam rotation direction 97. Oil is supplied from the auxiliary oil supply means 176 in the same direction as the cam rotation direction 97 to the sliding contact portion on the direction side, in this embodiment, the sliding contact portions of the exhaust side cam 78 and the exhaust side rocker arm 81. Therefore, a sufficient oil supply amount to the sliding contact portion in which the cam rotation direction 97 is opposite to the oil supply direction from the exhaust side rocker arm 81 can be ensured.

  The auxiliary oil supply means 176 communicates with the auxiliary oil supply passage 177 provided in the cylinder head 45 and extending in parallel with the axis of the intake side and exhaust side camshafts 77 and 79, and the auxiliary oil supply passage 177. Thus, since the oil injection hole 178 provided in the cylinder head 45 is provided, it is possible to easily adjust the oil supply amount from the auxiliary oil supply means 176 only by adjusting the diameter of the oil injection hole 178.

  Further, the intake valve 55 is arranged radially with respect to the combustion chamber 52, and the exhaust valve 56 is arranged along a plane perpendicular to the axes of the intake side and exhaust side camshafts 77, 79, and the auxiliary oil Since the supply means 176 is provided in the cylinder head 45 so as to be disposed on the exhaust valve 56 side, the oil injection holes 178 of the auxiliary oil supply means 176 are arranged on the intake line and the exhaust camshafts 77 and 79. It is not necessary to form in a complicated direction so as to face along the direction, and the structure of the auxiliary oil supply means 176 can be simplified.

  The cylinder head 45 is provided with an oil supply passage 165 for guiding oil from the cylinder body 44 side so as to communicate with the auxiliary oil supply passage 177 and a pair of branches branched from the downstream side of the oil supply passage 165. Oil passages 169 and 170 are provided in parallel with the auxiliary oil supply passage 177 so that the downstream side of the oil passages 169 and 170 communicates with the pair of rocker arm side oil passages 160 and 161, and the pair of oil passages One of the passages 169 and 170 is disposed at a position sandwiching the exhaust valve 56 between the auxiliary oil supply passage 177 and the both oil passages 169 and 170 are disposed between the intake valve 55 and the exhaust valve 56. The three passages 169, 170, 177 for guiding the oil are connected to the intake valve 55 and Are distributed on both sides of the exhaust valve 56 is arranged, it is possible to reduce the size of the cylinder head 45 by utilizing the space effectively.

  Further, the intake side and exhaust side rocker shafts 84 and 85 are inserted directly above the pair of oil passages 169 and 170 disposed below the branching portion 168d from the downstream side of the oil supply passage 165. Two sets of insertion holes 151, 152; 146 provided in the cylinder head 45 are arranged, and the oil passages 169, 170 are inserted into the rocker shaft oil passages 162, 163 via the insertion holes 151, 152; 146. The passages 173, 174, and 175 for guiding the oil are connected to the cylinder head 45 so as to extend vertically between the two sets of insertion holes 151, 152; 146 and the pair of oil passages 169, 170. Since the oil passage is provided, oil for guiding oil to the rocker arm side oil passages 160 and 161 when the internal combustion engine E is stopped is provided. Can be left stored in 69,170, quickly on the rocker arm side oil passage 160 and 161 at the start of the internal combustion engine E can supply oil, it is possible to eliminate the possibility that oil shortage occurs.

  A second camshaft support portion 83 that rotatably supports the intake side and exhaust side camshafts 77, 79 is provided in the cylinder head 45, and the intake valve 55 of the pair of oil passages 169, 170 is provided. A pair of camshaft lubrication passages 179 and 180 branched from the oil passage 169 corresponding to the side and the auxiliary oil supply passage 177, respectively, are the intake side and exhaust side camshafts 77 and 79, and the second camshaft. Since oil is supplied to the cylinder head 45 so as to supply oil between the support portion 83 and the oil passage 169 and the auxiliary oil supply passage 177, the intake side and exhaust side camshafts 77 and 79 are lubricated. Therefore, the oil passage structure can be simplified.

  Further, the pair of oil passages 169 and 170 and the auxiliary oil supply passage 177 are provided in the cylinder head 45 so as to be formed by processing from the same one side surface 45c of the cylinder head 45. The pair of oil passages 169 and 170 and the auxiliary oil supply passage 177 can be continuously formed without changing the fixing direction of the cylinder head 45, and the number of processing steps can be reduced.

  Further, the one side surface 45c of the cylinder head 45 accommodates a timing transmission mechanism 88 that transmits power from the crankshaft 42 to the intake side and exhaust side camshafts 77, 79 of all side surfaces of the cylinder head 45. Since the side surface is disposed on the opposite side of the storage chamber 104 formed in the engine body 29, there is no need to form a processing through-hole penetrating the outer wall 126 of the storage chamber 104. The rigidity of the cylinder head 45 can be ensured without reducing the rigidity.

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

29 ... Engine body 42 ... Crankshaft 44 ... Cylinder body 45 ... Cylinder head 52 ... Combustion chamber 55 ... Intake valve 56 ... Exhaust valve 76 ... Intake side cam 77 ... Intake side camshaft 78 ... Exhaust side cam 79 ... Exhaust side camshaft 80 ... Intake side rocker arm 81 ... Exhaust side rocker arm 82 ... Camshaft support 82a ... Intake side Camshaft bearing portion 82b ... exhaust side camshaft bearing portion 84 ... intake side rocker shaft 85 ... exhaust side rocker shaft 88 ... timing transmission mechanisms 92, 93 ... driven gear as a driven member 105 ... bearing wall 106 ... cam holder 109 ... intake side camshaft sliding contact surface 110 ... exhaust side camshaft sliding contact surface 151, 152 ... insertion holes 160, 161, Rocker arm side oil passages 162, 163 ... Rocker shaft inner oil passage 164 ... Communication oil passage 165 ... Oil supply passage 166 ... Intake side journal oil passage 167 ... Exhaust side journal oil passage 168 ..Branch oil passage 168d ... branch portions 169, 170 ... oil oil passages 171,172 ... grooves 173,174 ... communication passages C1, C2 ... center axis of insertion hole

Claims (8)

  The engine body includes an intake camshaft (77) having an intake cam (76) corresponding to the intake valve (55) and an exhaust camshaft (79) having an exhaust cam (78) corresponding to the exhaust valve (56). (29) is rotatably supported by the cylinder head (45), and is disposed between the intake valve (55) and the intake side cam (76) on the intake side rocker shaft (84) supported by the cylinder head (45). An intake side rocker arm (80) interposed is swingably supported, and the exhaust valve (55) and the exhaust side cam (78) are connected to the exhaust side rocker shaft (85) supported by the cylinder head (45). An exhaust-side rocker arm (81) interposed between the intake-side and the exhaust-side rocker arms (80, 81) is supported in a swingable manner. Rocker arm side oil passages (160, 161) for supplying oil to sliding contact portions with the intake side and exhaust side cams (76, 78) are provided, respectively, and these rocker arm side oil passages (160, 161) are provided. In the oil supply structure of the valve operating device for the internal combustion engine, the rocker shaft internal oil passages (162, 163) communicating with the internal combustion engine are provided in the intake side and the exhaust side rocker shafts (84, 85), respectively. The exhaust side camshaft (77, 79) is rotatably supported, and the intake side and the exhaust side camshaft (77, 79) are detoured by the camshaft support portion (82) provided in the cylinder head (45). The connecting oil passage (164) that guides oil from the cylinder body (44) side of the engine body (29). The camshaft support portion (82) is provided so as to communicate with an oil supply passage (165) provided in 45) and rotatably supports the intake side and exhaust side camshafts (77, 79). Are connected to the intake-side and exhaust-side journal oil passages (166, 167) for guiding oil to the intake-side and exhaust-side camshaft bearing portions (82a, 82b) and the rocker shaft inner oil passages (162, 163). In this way, the communication oil passage (in parallel with the intake side and exhaust side journal oil passages (166, 167) is guided so as to guide the oil to the oil passage (169, 170) provided in the cylinder head (45). 164) and a branched oil passage (168) provided in the camshaft support (82). Ill supply structure.   The camshaft support (82) is integrated with the bearing wall (105) provided integrally with the cylinder head (45), and the intake and exhaust camshaft bearings (82a, 82b) are connected to the bearing wall (105). And a cam holder (106) fixed to the bearing wall (105) so as to cooperate with the cam wall (105). The cam holder (106) includes a part of the oil supply path (165) and the oil The communication oil passage (164) communicating with the supply passage (165), the intake side and exhaust side journal oil passages (166, 167), and a part of the branch oil passage (168) are provided. An oil supply structure for a valve operating apparatus for an internal combustion engine according to claim 1.   The pair of oil passages (169, 170) individually communicates with the rocker shaft internal oil passages (162, 163) provided in the intake side and exhaust side rocker shafts (84, 85), respectively. Provided in the cylinder head (45), the branch oil passage (168) is branched into the pair of oil passages (169, 170) so as to communicate with each other, and provided in the camshaft support (82). The oil supply structure for a valve operating apparatus for an internal combustion engine according to claim 2.   The valve operating device for an internal combustion engine according to claim 3, wherein a branch portion (168d) of the branch oil passage (168) is provided at a joint portion between the bearing wall (105) and the cam holder (106). Oil supply structure.   The cam holder (106) is formed so as to integrally have a portion sandwiching the intake side and exhaust side camshafts (77, 79) with the bearing wall (105), and the communication oil passage (164). Is formed to extend linearly in a direction orthogonal to the direction of arrangement of the intake side and exhaust side camshafts (77, 79), and the intake side and exhaust side journal oil passages (166, 167) are formed as the intake side. Of the intake side camshaft sliding surface (109) and the exhaust side camshaft sliding contact surface (110) formed on the cam holder (106) so as to be in sliding contact with the exhaust side and exhaust side camshafts (77, 79), respectively. The oil supply for a valve operating apparatus for an internal combustion engine according to any one of claims 2 to 4, wherein the oil supply is formed so as to connect an uppermost part and the communication oil passage (164). Elephants.   Grooves (171, 172) for opening the intake side and exhaust side journal oil passages (166, 167) on the intake side and exhaust side camshaft sliding contact surfaces (109, 110) are provided on the intake side and the exhaust side. The oil supply structure for a valve operating apparatus for an internal combustion engine according to claim 5, wherein the oil supply structure is formed so as to extend in an axial direction of the side camshaft (77, 79).   Of the intake valve (55) and the exhaust valve (56), a plurality of one valve (55) are arranged for one combustion chamber (52) and are arranged radially with respect to the combustion chamber (52). The other valve (56) of the intake valve (55) and the exhaust valve (56) is disposed along a plane perpendicular to the axis of the intake side and exhaust side camshafts (77, 79). And a timing transmission mechanism (88) for transmitting rotational power from the crankshaft (42) to the shaft ends of the intake side and exhaust side camshafts (77, 79) protruding from the camshaft support (82). ) Are fixed, and are arranged on the one valve (55) side of the intake side and exhaust side camshaft sliding contact surfaces (109, 110). One Kamshi The cam holder (106) is formed so that the shaft sliding contact surface (109) is offset from the other cam shaft sliding contact surface (110) toward the timing transmission mechanism (88), and the communication oil passage (164) passes through the center in the width direction of the other camshaft sliding contact surface (110) on a projection view on the plane including the axes of the intake side and exhaust side camshafts (77, 79). The groove (171) provided in the cam holder (106) and formed in the one camshaft sliding contact surface (109) is formed in the groove (172) formed in the other camshaft sliding contact surface (110). The oil supply structure for a valve operating apparatus for an internal combustion engine according to claim 6, wherein the oil supply structure is longer on the timing transmission mechanism (88) side.   One of the intake valve (55) and the exhaust valve (56) (55) is disposed with respect to one combustion chamber (52) and is radially disposed with respect to the combustion chamber (52). A pair of insertion holes (151, 152) for inserting and fixing a pair of rocker shafts (84) corresponding to the one valve (55) of the intake side and exhaust side rocker shafts (84, 85). Are provided in the cylinder head (45) independently of each other so that the extension lines of the central axes (C1, C2) of the insertion holes (151, 152) intersect each other, and the oil passage (169) 170), a pair of communication passages (173, 174) for guiding oil from the insertion holes (151, 152) to the pair of insertion holes (151, 152) are provided in the cylinder head (45) independently of each other. Oil supply mechanism for an internal combustion engine for a valve gear according to any one of 7.

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