JP2008082311A - Lubrication structure of 4-stroke engine for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 4-stroke engine for a vehicle including a rocker arm, which is supported on a rocker shaft above a cam shaft so as to swing, and is interlocked and connected to a stem end of an engine vavle, and an oil passage provided on a cylinder head for guiding oil from an oil pump, and capable of supplying oil for lubrication between the stem end of the engine valve and the rocker arm without complicated drilling process. <P>SOLUTION: A center oil passage 111 is coaxially provided on the cam shaft 65, and an oil ejection hole 112 extending radially and leading to the center oil passage 111 in a position corresponding to the rocker arm 66 is provided on the cam shaft 65. A guide wall part 114 having an approximately U-shape in cross section opening to a rocker arm 66 side so as to receive oil ejected from the oil ejection hole 112, and forming an oil groove 115 of which the width is narrowed as getting upward, is fixed on an opposite side of the cylinder head 27 with respect to the rocker arm 66. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a camshaft is rotatably supported by a cylinder head coupled to a cylinder block in which an axis of a cylinder bore is inclined forward, and is provided on the camshaft on a rocker shaft disposed above the camshaft. A rocker arm having a cam abutting portion that abuts against the cam is pivotally supported, and the other end of the rocker arm is linked and connected to a stem end of an engine valve that is arranged to open and close on the cylinder head. In particular, the present invention relates to a four-cycle engine for a vehicle in which an oil passage for guiding oil from an oil pump is provided in the cylinder head, and more particularly, to an improvement in a lubricating structure for supplying lubricating oil between a stem end and a rocker arm of an engine valve.

In order to supply oil between the stem end of the intake valve and the rocker arm, an oil passage is provided in the head cover so as to communicate with the oil passage of the cylinder head (see Patent Document 1).
Japanese Patent No. 3466352

  However, the one disclosed in Patent Document 1 requires a drilling process for forming a complex oil passage in the head cover, resulting in an increase in cost due to an increase in the number of processing steps.

  The present invention has been made in view of such circumstances, and has a lubricating structure for a four-cycle engine for a vehicle that can supply lubricating oil between a stem end and a rocker arm of an engine valve without requiring a complicated drilling process. The purpose is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, a camshaft is rotatably supported by a cylinder head coupled to a cylinder block in which the axis of a cylinder bore is tilted forward, and is disposed above the camshaft. A rocker shaft having a cam abutting portion abutting on a cam provided on the camshaft at one end is supported on the rocker shaft so as to be swingable, and a stem of an engine valve disposed on the cylinder head so as to be opened and closed. In a four-cycle engine for a vehicle in which the other end of the rocker arm is interlocked and connected to an end, and an oil passage that guides oil from an oil pump is provided in the cylinder head, a central oil passage that leads to the camshaft and the oil passage Is provided coaxially and communicates with the central oil passage at a position corresponding to the rocker arm. A substantially U-shaped cross section provided with an oil ejection hole extending in a radial direction and opened to the rocker arm side so as to receive oil ejected from the oil ejection hole on the side opposite to the cylinder head with respect to the rocker arm The guide wall part which forms the oil groove which has a shape and was narrowed as it goes upwards is fixedly arranged.

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the guide wall portion covers the camshaft, the rocker shaft, and the rocker arm, and is coupled to the cylinder head; It is characterized by comprising a pair of side walls provided integrally with the head cover so as to protrude toward the cylinder head side.

  The invention according to claim 3 is characterized in that, in addition to the configuration of the invention according to claim 2, the protruding amount of the side walls from the head cover is set to increase as it goes upward.

  In addition to the structure of any one of claims 1 to 3, the invention described in claim 4 is arranged so that a roller as the cam contact portion is brought into rolling contact with the cam at one end of the rocker arm. The camshaft is pivotally supported, and the oil ejection hole is provided in the camshaft so as to open to an outer peripheral surface of the cam.

  The intake side rocker arm 66 of the embodiment corresponds to the rocker arm of the present invention, the intake side cam 68 of the embodiment corresponds to the cam of the present invention, and the intake side rocker shaft 84 of the embodiment corresponds to the rocker shaft of the present invention. .

  According to the first aspect of the present invention, a part of the oil ejected from the oil ejection hole of the camshaft is received by the oil groove of the guide wall portion and proceeds upward in the oil groove, but the width of the oil groove is upward. The oil gathered at the top of the oil groove falls from the oil groove and is supplied between the stem end of the engine valve and the rocker arm, making it unnecessary to process a dedicated oil passage. With a simple structure, lubricating oil can be supplied between the stem end of the engine valve and the rocker arm.

  According to the second aspect of the present invention, since the guide wall portion is formed integrally with the head cover, a dedicated member for forming the guide wall portion is not required, and an increase in the number of parts is avoided, and a pair of side walls are used. The strength of the head cover can be increased by reinforcing the head cover.

  According to the invention of claim 3, since the oil groove is narrowed as it goes upward, the oil collects at the upper part of the oil groove, but the protruding amount of the pair of side walls from the head cover is upward. Since the oil becomes larger as it goes, it can be guided to a desired position while holding the collected oil up to the upper part in the oil groove, and can be efficiently supplied between the stem end and the rocker arm of the engine valve, and the lubrication performance is improved.

  According to the fourth aspect of the present invention, oil can be effectively supplied between the roller and the cam, and the oil splashed up by the rotation of the roller can be effectively guided to the guide groove. The oil can be guided to the guide groove to further improve the lubrication performance.

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

  1 to 8 show an embodiment of the present invention, FIG. 1 is a side view of a motorcycle, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is 3-3 of FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 2, FIG. 5 is a sectional view taken along line 5-5 of FIG. 4, FIG. 6 is an enlarged view of a portion indicated by arrow 6 in FIG. 7 is an enlarged view, and FIG. 8 is a view of the head cover as viewed from the direction of arrows 8-8 in FIG.

  In FIG. 1, a motorcycle body frame F includes a head pipe 13 that supports a front fork 11 and a steering handle 12 that pivotally support a front wheel WF, and a main pipe that extends rearward and downward from the head pipe 13. A frame 14 and a pair of left and right rear frames 15 extending backward from the rear portion of the main frame 14 are provided. The main frame 14 has a rear portion of a swing arm 16 supported by a vehicle body frame F so as to be swingable up and down. A four-cycle engine E that exerts power to drive the rear wheel WR that is pivotally supported is supported. A rear cushion 17 is provided between the swing arm 16 and the rear frame 15.

  A luggage box 18 is disposed above the engine E so as to be supported by the rear frame 15. The fuel tank 19 disposed behind the rear box 18 is also supported by the rear frame 15. The vehicle body frame F, the luggage box 18 and the fuel tank 19 are covered with a vehicle body cover 20, and a riding seat 21 for placing a passenger is disposed on the vehicle body cover 20.

  2 and 3, the engine body 22 of the engine E has a crankcase 25 in which a pair of case halves 23 and 24 are coupled, and a cylinder bore 29 in which the axis C is tilted forward until it is substantially horizontal. A cylinder block 26 coupled to the crankcase 25, a cylinder head 27 coupled to the cylinder block 26, and a head cover 28 coupled to the cylinder head 27, and the crankcase 25 is rotatable. A piston 31 slidably fitted to the cylinder bore 29 is connected to a crankshaft 30 supported via a connecting rod 32.

  The output of the engine E, that is, the rotational power of the crankshaft 30 is transmitted to the rear wheel WR via the start clutch 35, the damper rubber 36, the transmission clutch 37, the gear transmission 38, and the chain transmission 39.

  The gear transmission 38 has a main shaft 40 and a countershaft 41 that have an axis parallel to the crankshaft 30 and are rotatably supported by the crankcase 25, and can selectively establish the mainshaft 40 and the countershaft. 41 is provided with a plurality of gear stages, for example, first to fourth gear stages G1, G2, G3, G4.

  One end of the crankshaft 30 protruding from one of the pair of case halves 23, 24 constituting the crankcase 25 is connected to a drive gear 42 via a starting clutch 35, and is driven to mesh with the drive gear 42. A gear 43 is supported on the end of the main shaft 40 projecting from the one case half 23 so as to be relatively rotatable. The driven gear 43 is connected to the clutch outer 44 of the speed change clutch 37 via the damper rubber 36. The

  The transmission clutch 37 is a multi-plate clutch that connects and disconnects between the clutch inner 46 coupled to the main shaft 40 and the clutch outer 44 by the action of the release cam mechanism 45 according to the rider's operation. The gear trains G1 to G4 can be selectively established in the disconnected state. The starting clutch 35 and the transmission clutch 37 are covered with a first crankcase cover 47 coupled to the one case half 23.

  A chain type transmission device 39 is provided between the end of the countershaft 41 protruding from the other 24 of the case halves 23 and 24 and the rear wheel WR. A driving sprocket 48 fixed to the end, a driven sprocket 49 (see FIG. 1) fixed to the axle of the rear wheel WR, and an endless chain 50 wound around the driving sprocket 48 and the driven sprocket 49.

  A rotor 52 of a generator 51 is fixed to the other end portion of the crankshaft 30 protruding from the other 24 of the case halves 23 and 24, and the other case half is covered so as to cover the generator 51. A stator 53 of the generator 51 is fixed to a second crankcase cover 54 that is coupled to the body 24.

  4 and 5 together, a combustion chamber 57 is formed between the cylinder block 26 and the cylinder head 27 so that the top of the piston 31 faces, and the cylinder head 27 includes the combustion chamber 57. An intake port 58 capable of communicating with the cylinder head 27 is provided so as to open on the upper side surface of the cylinder head 27, and an exhaust port 59 capable of communicating with the combustion chamber 57 is opened on the lower side surface of the cylinder head 27. To be provided. The cylinder head 27 is opened and closed with an intake valve 60 for switching communication / blocking between the intake port 58 and the combustion chamber 57 and an exhaust valve 61 for switching communication / blocking between the exhaust port 59 and the combustion chamber 57. The intake valve 60 and the exhaust valve 61 are urged in the valve closing direction by the valve springs 62 and 63, respectively.

  A valve operating device 64 that opens and closes the intake valve 60 and the exhaust valve 61 is accommodated between the cylinder head 27 and the head cover 28, and the valve operating device 64 has an axis parallel to the crankshaft 30. A camshaft 65 that rotates around, and an intake-side rocker arm 66 and an exhaust-side rocker arm 67 that swing according to the rotation of the camshaft 65 are provided. Thus, the camshaft 65 at a portion corresponding to the intake side rocker arm 66 protrudes outward in the radial direction from the arc-shaped base circle 68a centering on the axis of the camshaft 65 and the base circle 68a. An intake side cam 68 having a high position portion 68b is integrally provided, and a portion corresponding to the exhaust side rocker arm 67 is provided on the cam shaft 65 with an arc-shaped base circle portion 69a centering on the axis of the cam shaft 65, and An exhaust-side cam 69 having a high-order portion 69b that protrudes radially outward from the base circle portion 69a is integrally provided.

  Referring also to FIG. 6, a cam holder 70 having first and second support wall portions 70 a and 70 b arranged at intervals in a direction along the axis of the cam shaft 65 is fastened to the cylinder head 27. A small-diameter shaft 65a coaxially and integrally provided at one end of the camshaft 65 is rotatably supported on the first support wall 70a via a ball bearing 71 with a seal. The second support wall 70b has a support hole 72 having a size that allows the cam shaft 65 having the intake side cam 68 and the exhaust side cam 69 to be inserted from one end thereof. The ball bearing 73 is interposed between the inner peripheral portion of the support hole 72 and the camshaft 65.

  On the other hand, an insertion hole 74 that also opens on the coupling surface of the cylinder head 27 to the head cover 28 is provided in the cylinder head 27 corresponding to the support hole 72 and is sandwiched between the cylinder head 27 and the head cover 28. The insertion hole 74 is closed by a cap 76 integral with the gasket 75.

  Rotational power from the crankshaft 30 is transmitted to the camshaft 65 through a timing transmission mechanism 77 at a reduction ratio of 1/2. Thus, the timing transmission mechanism 77 includes a drive sprocket 78 (see FIG. 2) fixed to the crankshaft 30 between the generator 51 and the other case half 24, and the second support wall portion 70b. A driven sprocket 79 fastened to the other end of the camshaft 65 projecting from the drive shaft and an endless timing chain 80 wound around the drive and driven sprockets 78, 79, over the cylinder block 26 and the cylinder head 27. A chain passage 81 for running the timing chain 80 is provided.

  The intake side rocker arm 66 is swingably supported by an intake side rocker shaft 84 supported by the cam holder 70 above the camshaft 65, and one end of the intake side rocker arm 66 has an intake side. A roller 85 as a cam abutting portion that rolls into contact with the cam 68 is pivotally supported, and the other end of the intake side rocker arm 66 is screwed into the intake side rocker arm 66 so that the advance / retreat position can be adjusted. By being in contact with the stem end 60a of 60, the intake valve 60 is linked and connected.

  On the other hand, the exhaust side rocker arm 67 is supported so as to be swingable by an exhaust side rocker shaft 87 supported by the cam holder 70 below the camshaft 65. A roller 88 that is in rolling contact with the exhaust side cam 69 is pivotally supported, and a tappet screw 89 that is screwed so that the advance / retreat position can be adjusted is screwed to the other end of the exhaust side rocker arm 67, and the tappet screw 89 is connected to the exhaust valve 61. The stem end (not shown) is contacted.

  Referring also to FIG. 7, the exhaust valve 61 is slightly opened in the compression process by the operation of the decompression mechanism 90 in the region where the engine speed is low, and the decompression mechanism 90 is connected to the camshaft 65. A decompression shaft 91 inserted into the camshaft 65 so as to be rotatable about an axis parallel to the camshaft 65, a weight 92 fixed to a projecting end portion of the decompression shaft 91 from the camshaft 65, the weight A rotation restricting member 93 that is fastened to the camshaft 65 so as to restrict the rotation range of the weight 92 and the decompression shaft 91, surrounds the decompression shaft 91, and both ends are the weight 92 and the driven sprocket. And a torsion spring 94 engaged with 80.

  At the eccentric position of the camshaft 65, a bottomed insertion hole 95 having an inner end blocking portion corresponding to the exhaust side cam 69 and opening at the other end of the camshaft 65 is connected to the axis of the camshaft 65. The decompression shaft 91 is rotatably inserted into the insertion hole 95. In addition, the camshaft 65 at a position corresponding to the space between the intake side cam 68 and the exhaust side cam 69 has an opening that allows a portion of the decompression shaft 91 to face at a position corresponding to the base circle portion 69a of the exhaust side cam 69. 96 is provided, and at one end of the exhaust side rocker arm 67, a projecting part 97 is inserted into the opening 96 with the roller 88 in contact with the base circular part 69a of the exhaust side cam 69. Is projected. In addition, on the outer periphery of the decompression shaft 91 at a portion corresponding to the opening 96, an arc-shaped push-up surface 98 that abuts against the protrusion 97 and slightly pushes up one end of the exhaust-side rocker arm 67, and the push-up surface A concave portion 99 that is recessed radially inward from both circumferential ends of 98 is provided. When the concave portion 99 is at a position corresponding to the opening portion 96, the protrusion 97 is not pushed up by the decompression shaft 91. .

  The regulating member 93 is fastened to the camshaft 65 so as to sandwich the driven sprocket 79 between the camshaft 65 and is inserted into the regulating member 93 and the driven sprocket 79 at a position offset from the axis of the camshaft 65. A pair of bolts 100, 100 are screwed onto the camshaft 65. Further, the restricting member 93 is integrally provided with a thrust receiver 93 a that prevents the decompression shaft 91 from being detached from the insertion hole 95 by being close to and facing the outer end of the decompression shaft 91.

  The weight 92 has one end fixed to the decompression shaft 91, an arm 92a extending radially outward of the decompression shaft 91, and one end in the circumferential direction connected to the other end of the arm 92a and driven. An arc portion 92b extending in an arc shape along the outer periphery of the sprocket 79 is integrally provided.

  The restricting member 93 is in contact with the arm portion 92a of the weight 92 so as to restrict the rotation range of the weight 92 around the axis of the decompression shaft 91. The first and second stoppers 93b and 93c The torsion spring 94 exerts a spring force that urges the weight 92 in a direction in which the weight 92 is brought into contact with the first stopper 93b.

  Thus, when the camshaft 65 is rotated by the power transmission from the timing transmission mechanism 77, the weight is placed on the straight line L passing through the axis of the camshaft 65 and the axis of the decompression shaft 91 by the centrifugal force acting on the weight 92. The weight 92 is about to turn to the side where the center of gravity of 92 is located. When the camshaft 65 is in a stopped state, the weight 92 is in a position in contact with the first stopper 93b as shown by a chain line in FIG. However, when the engine speed, that is, the rotational speed of the camshaft 65 is increased, the weight 92 is rotated to a position where it comes into contact with the second stopper 93c as shown by a chain line in FIG.

  That is, when the engine speed is low, the weight 92 is not in contact with the second stopper 93c, and in this state, the push-up surface 98 of the decompression shaft 91 is at a position corresponding to the opening 96, and the exhaust cam When the base circular portion 69a of the 69 is in the rotational position corresponding to the roller 88 of the exhaust side rocker arm 67, that is, in the compression process, the protrusion 97 of the exhaust side rocker arm 67 is slightly pushed up by the push-up surface 98. The cranking torque is reduced by slightly opening 61 and reducing the pressure in the combustion chamber 57 slightly.

  Further, after the engine speed increases and the weight 92 comes into contact with the second stopper 93c, the concave portion 99 of the decompression shaft 91 is at a position corresponding to the opening 96. In this state, the protrusion of the exhaust side rocker arm 67 The pushing force from the decompression shaft 91 does not act on the portion 97, the roller 88 of the exhaust side rocker arm 67 rolls into contact with the base circle portion 68a of the exhaust side cam 69, and the exhaust valve 61 remains closed during the compression process. is there.

  Referring to FIG. 3, an oil pump 102 is fixedly disposed in the lower part of the crankcase 25, and a rotating shaft 104 of the oil pump 102 includes a drive gear 103 fixed to the crankshaft 30, Rotational power is transmitted from the crankshaft 30 by the driven gear 104 fixed to the rotary shaft 104 so as to mesh with the drive gear 103. Thus, the drive gear 103 is fixed to the crankshaft 30 outside one case half 23 in the crankcase 25.

  The oil in the precursor crankcase 25 passes through an oil strainer 106 fixedly disposed in the lower part of the crankcase 25 and is sucked up by the oil pump 102. The oil discharged from the oil pump 102 is one of the crankcases 25. Guided to an oil passage 107 provided in the case half 23.

  The cam holder 70 is fastened to the crankcase 25 together with the cylinder head 27 and the cylinder block 26 by, for example, four through bolts 108..., And the first support wall portion 70 a of the cam holder 70 among the through bolts 108. An annular oil passage 109 communicating with the oil passage 107 is formed between the through bolt 108 inserted into the cylinder head 27 and the cylinder block 26, and the oil passage 109 faces one end of the camshaft 65. In this manner, the oil reservoir 110 is formed in the first support wall 70 a of the cam holder 70.

  The camshaft 65 is coaxially provided with a central oil passage 111 having one end opened at one end of the camshaft 65 to communicate with the oil reservoir 110 and the other end closed at a position corresponding to the exhaust side cam 69. It is done. The camshaft 65 is provided with oil ejection holes 112 and 113 extending in the radial direction through the central oil passage 110 at positions corresponding to the intake-side rocker arm 66 and the exhaust-side rocker arm 67, respectively. The oil ejection hole 112 is provided in the camshaft 65 so as to open the outer end on the outer circumferential surface of the base circle portion 68 a of the intake side cam 68, and the oil ejection hole 113 is the outer circumference of the base circle portion 69 a of the exhaust side cam 69. The camshaft 65 is provided with an outer end opened on the surface.

  Referring also to FIG. 8, on the side opposite to the cylinder head 27 with respect to the intake side rocker arm 66, the intake side rocker arm 66 is adapted to receive the oil ejected from the oil ejection holes 112 provided in the intake side cam 68. A guide wall portion 114 that has an approximately U-shaped cross-sectional shape that is open to the side and that forms an oil groove 115 with a width that decreases toward the top is fixedly disposed. In addition, the guide wall portion 114 includes a head cover 28 and a pair of side walls 116 and 117 that are provided integrally with the head cover 28 so as to protrude toward the cylinder head 27. The amount of protrusion from the head cover 28 is set to increase as it goes upward.

  In addition, the intake side rocker arm 66 is linked to the stem end 60a of the intake valve 60 and the oil groove 115 flows upward in the oil groove 115 at a position corresponding to the upper portion of the connecting portion. Are provided in two stages.

  Next, the operation of this embodiment will be described. A central oil passage 111 that communicates with an annular oil passage 109 provided in the cylinder head 27 so as to surround the through bolt 108 is provided coaxially on the camshaft 65 of the valve operating device 64. In addition, an oil ejection hole 112 extending in the radial direction through the central oil passage 111 is provided at a position corresponding to the intake side rocker arm 66 supported so as to be swingable by the intake side rocker shaft 84 above the camshaft 65. The intake side rocker arm 66 has a substantially U-shaped cross-sectional shape that is open to the intake side rocker arm 66 so as to receive the oil ejected from the oil ejection hole 112 on the side opposite to the cylinder head 27. A gas groove 115 that has an oil groove 115 having a width that is narrowed toward the top. De wall 114 is fixedly disposed.

  Accordingly, a part of the oil ejected from the oil ejection hole 112 of the camshaft 65 is received by the oil groove 115 of the guide wall portion 114 and proceeds upward in the oil groove 115. Moreover, since the width of the oil groove 115 is narrowed upward, the oil gathered at the upper part of the oil groove 115 falls from the oil groove 115, and the tappet screw 86 of the stem end 60 a of the intake valve 60 and the intake side rocker arm 66. The lubricating oil is supplied between the stem end 60a of the intake valve 60 and the tappet screw 86 of the intake side rocker arm 66 with a simple structure that eliminates the need for processing of a dedicated oil passage. Can be supplied.

  In addition, the intake side rocker arm 66 is linked to the stem end 60a of the intake valve 60, and the oil groove 115 flows upward in the oil groove 115 at a position corresponding to the upper portion of the connecting portion. Since the step portions 118 and 119 that face each other are provided in two stages, oil can be effectively dropped between the stem end 60a of the intake valve 60 and the tappet screw 86 of the intake side rocker arm 66.

  Further, the guide wall portion 114 includes a head cover 28 coupled to the cylinder head 27 and a pair of side walls 116 and 117 provided integrally with the head cover 28 so as to protrude toward the cylinder head 27 side. It is possible to increase the strength of the head cover 28 by reinforcing the head cover 28 with the pair of side walls 116 and 117 while avoiding an increase in the number of parts by eliminating the need for a dedicated member for forming the portion 114.

  Further, since the protruding amount of the side walls 116, 117 from the head cover 28 is set to increase as it goes upward, the width of the oil groove 115 is narrowed as it goes upward, so that the oil groove 115 is formed at the upper part of the oil groove 115. The gathered oil is guided to a desired position while being held up to the upper part in the oil groove 115 because the protruding amount of the pair of side walls 116 and 117 from the head cover 28 increases upward. Oil can be efficiently supplied between the stem end 60a of the valve 60 and the tappet screw 86 of the intake side rocker arm 66, thereby improving the lubrication performance.

  Further, since the oil ejection hole 112 is opened on the outer peripheral surface of the intake side cam 68 that rolls and contacts the roller 85 that is pivotally supported on one end of the intake side rocker arm actuator 66, it is effective between the roller 85 and the intake side cam 68. In addition, the oil splashed by the rotation of the roller 85 can be effectively guided to the guide groove 115, so that more oil is guided to the guide groove 115 to further improve the lubrication performance. be able to.

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

1 is a side view of a motorcycle. FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is an enlarged view of a portion indicated by arrow 6 in FIG. 2. FIG. 7 is an enlarged view taken along arrow 7 in FIG. 6. It is the figure which looked at the head cover from the 8-8 line arrow direction of FIG.

Explanation of symbols

26 ... Cylinder block 27 ... Cylinder head 28 ... Head cover 29 ... Cylinder bore 60 ... Intake valve 60a as engine valve ... Stem end 65 ... Camshaft 66 ... Intake side Rocker arm 68 ... intake side cam 84 ... intake side rocker shaft 85 ... roller 102 as cam contact portion ... oil pump 109 ... oil passage 111 ... central oil passage 112 ... Oil ejection hole 114 ... guide wall 115 ... oil groove 116, 117 ... side wall C ... axis of cylinder bore

Claims (4)

  A camshaft (65) is rotatably supported by a cylinder head (27) coupled to a cylinder block (26) in which the axis (C) of the cylinder bore (29) is tilted forward, and above the camshaft (65). A rocker arm (66) having a cam abutting portion (85) abutting against a cam (68) provided on the camshaft (65) is pivotally supported on a rocker shaft (84) disposed on the camshaft (65). The other end of the rocker arm (66) is linked and connected to the stem end (60a) of the engine valve (60) arranged to be openable and closable on the cylinder head (27). In a four-cycle engine for a vehicle in which an oil passage (109) for guiding oil is provided in the cylinder head (27), the oil passage is inserted into the camshaft (65). A central oil passage (111) leading to (109) is provided coaxially, and an oil ejection hole (112) extending radially through the central oil passage (111) is provided at a position corresponding to the rocker arm (66). The rocker arm (66) is open to the rocker arm (66) side so as to receive the oil ejected from the oil ejection hole (112) on the side opposite to the cylinder head (27). A lubricating structure for a four-cycle engine for a vehicle, characterized in that a guide wall portion (114) that has an oil groove (115) that has a transverse cross-sectional shape and that narrows toward the top is fixedly arranged.   A head cover (28) in which the guide wall (114) covers the camshaft (65), the rocker shaft (84) and the rocker arm (66) and is coupled to the cylinder head (27); The lubricating of a four-cycle engine for a vehicle according to claim 1, comprising a pair of side walls (116, 117) provided integrally with the head cover (28) so as to protrude toward the (27) side. Construction.   The lubricating structure for a four-cycle engine for a vehicle according to claim 2, wherein the projecting amount of the both side walls (116, 117) from the head cover (28) increases as it goes upward.   The roller (85), which is the cam contact portion, is pivotally supported on one end of the rocker arm (66) so as to be in rolling contact with the cam (68), and the oil ejection hole (112) is provided on the cam (68). The lubricating structure for a four-cycle engine for a vehicle according to any one of claims 1 to 3, wherein the lubricating structure is provided on the camshaft (65) so as to open to an outer peripheral surface.

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