JP2009162192A - Lubrication structure of valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the lubrication structure of a valve train, miniaturizing a cylinder head by arranging a head bolt in a position overlapping with a cam holder, and sufficiently maintaining introduction of lubricating oil into the intra-axial hollow oil passage of a camshaft. <P>SOLUTION: In this lubrication structure of the valve train, bolt fastening operation holes 138i, 138e are formed in some of the lower bearing surfaces 135i, 135e of a cam bearing portion 135, the cam holder 150 is formed with a first holder inner oil passage E6 communicating with the communication port of the head inner oil passage E4 of the cylinder head 13 and arranged in a position above the bolt fastening operation holes 138i, 138e and second holder inner oil passages E7, E8 extending from the first holder inner oil passage E6 to the axial directions of the camshafts and having communication ports opened in the positions of upper bearing surfaces 150i, 150e at least dislocated from the positions above the bolt fastening operation holes 138i, 138e, and introduction oil passages 66vh, 67vh formed by penetrating through a radial direction at a journal portion from the intra-axial hollow oil passages F, F formed in the camshafts 66, 67 communicate with the communication port of the second holder inner oil passage E8 of the cam holder 150. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lubricating structure in a valve mechanism of an internal combustion engine.

  In a valve operating mechanism in which a cam bearing portion and a cam holder formed on a cylinder head are rotatably supported so that the cam shaft is sandwiched between corresponding semicircular bearing surfaces, lubricating oil discharged from an oil pump is Guided to the annular oil groove formed on the bearing surface, introduced from the annular oil groove to the hollow oil passage in the cam shaft via the introduction oil passage drilled in the cam journal, and operated from the hollow oil passage in the shaft. Patent Document 1 discloses a lubricating structure in which lubricating oil is supplied to each sliding portion of the mechanism for lubrication.

JP 2004-293435 A

  In the lubrication structure of the valve mechanism disclosed in Patent Document 1, the bolt hole of the head bolt that fastens the cylinder head to the crankcase together with the cylinder block is used to guide the lubricating oil to the cam holder. Is formed at a position away from the bearing portion of the cam bearing portion in the axial direction.

If a bolt fastening operation hole for fastening the head bolt is provided in the bearing portion of the cam bearing portion so that the head bolt overlaps with the cam holder, the cam journal portion of the cam shaft is exposed at the bolt fastening operation hole, and the upper side of the cam holder Lubricating oil to be introduced from the annular oil groove formed in the bearing surface into the camshaft hollow oil passage easily leaks from the exposed surface of the cam journal to the bolt fastening work hole. Lubricating oil is not sufficiently introduced into the inner hollow oil passage, and the other lubricating parts of the valve operating mechanism cannot be well lubricated.
Therefore, in the cited document 1, the bolt hole is provided in the axial direction away from the bearing portion of the cam bearing portion, and therefore it is difficult to reduce the size of the cylinder head.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a head bolt at a position overlapping with the cam holder to reduce the size of the cylinder head and to lubricate the cam shaft to the hollow oil passage in the shaft. This is to provide a lubrication structure for a valve mechanism that can maintain the introduction of oil well.

In order to achieve the above object, the invention according to claim 1 is configured such that an internal combustion engine is configured by stacking a cylinder block and a cylinder head sequentially on a crankcase and fastening them with a head bolt,
A cam bearing portion in which a lower bearing surface is formed on the cylinder head is formed, and cam holders in which an upper bearing surface is formed opposite to the lower bearing surface of the cam bearing portion, In the valve mechanism coupled to the cam bearing portion so as to be pivotally supported by pinching, a bolt fastening work hole of the head bolt is formed in a part of the lower bearing surface, and the cam head is formed in the cylinder head. An in-head oil passage that opens a connection port is formed in a coupling surface of the bearing portion with the cam holder, and the cam holder communicates with the connection port of the in-head oil passage and is disposed above the bolt fastening work hole. A first holder oil passage, and a connecting port that opens from the first holder oil passage in the axial direction of the cam shaft and opens at a position away from at least an upper position of the bolt fastening work hole on the upper bearing surface. Second holder An oil passage is formed, and an introduction oil passage formed by penetrating in a radial direction from a hollow oil passage in the cam shaft in the journal portion communicates with a connection port of the oil passage in the second holder of the cam holder. A lubrication structure for the valve operating mechanism was adopted.

  According to a second aspect of the present invention, in the lubricating structure for a valve operating mechanism according to the first aspect, the cam shaft is formed in a thrust receiving groove formed in a circumferential direction above the bolt fastening work hole on the lower bearing surface. The flange formed in the journal portion of the cam shaft is slidably fitted to restrict the axial movement of the cam shaft, and the cam holder penetrates upward from the thrust receiving groove to form an oil recovery hole. It is characterized by.

  According to a third aspect of the present invention, in the lubricating structure for a valve operating mechanism according to the first or second aspect, the second holder internal oil passage of the cam holder extends in an axial direction from the first holder internal oil passage. A directional oil passage and an end of the coaxial oil passage that extends in a circumferential direction to a position off the upper position of the bolt fastening work hole of the upper bearing surface and opens a connection port toward the journal portion of the cam shaft It is characterized by comprising an annular oil groove.

  According to a fourth aspect of the present invention, in the lubrication structure for a valve operating mechanism according to the third aspect, the first holder internal oil passage and the annular oil groove of the cam holder are parallel to each other perpendicular to the cam shaft. A holder fixing bolt hole of a bolt that is formed along and connects the cam holder to the cam bearing portion of the cylinder head is drilled between the oil path in the first holder and the annular oil groove in the axial direction of the cam shaft. It is characterized by being.

  According to a fifth aspect of the present invention, in the lubricating structure for a valve operating mechanism according to any one of the first to fourth aspects, the oil passage in the head of the cylinder head is in the axial direction of the cam shaft. It is characterized by being formed at the same position as the bolt fastening work hole.

  According to the lubricating structure of the valve mechanism according to claim 1, the bolt fastening work hole of the head bolt is formed in a part of the lower bearing surface of the cam bearing portion, and the head bolt is disposed at a position overlapping the cam holder. Since it is a structure, size reduction of a cylinder head can be achieved.

  The cam holder is formed with a first holder oil passage communicating with the connection port of the head oil passage and a second holder oil passage opening the connection port at a position away from the upper position of the bolt fastening work hole, Since the lubricating oil is guided to the in-shaft hollow oil passage through the introduction oil passage of the camshaft communicating with the connection port, the cam is taken from the connection port of the second holder internal oil passage at a position away from the upper position of the bolt fastening work hole. With a simple oil passage configuration in which the lubricating oil is introduced into the shaft hollow oil passage of the shaft, leakage of the lubricating oil to the bolt fastening work hole is suppressed, and the lubricating oil is sufficiently introduced into the hollow oil passage in the shaft. The lubricating oil can be smoothly supplied from the in-shaft hollow oil passage to each required lubricating portion of the valve operating mechanism for good lubrication.

  According to the lubricating structure of the valve mechanism according to claim 2, the flange formed in the journal portion of the cam shaft in the thrust receiving groove formed in the circumferential direction above the bolt fastening work hole in the upper bearing surface of the cam holder. The sliding movement of the camshaft is restricted so that the cam shaft is prevented from moving in the axial direction, and an oil recovery hole is formed by penetrating upward from the thrust receiving groove. The lubricating oil entering the oil recovery hole opened above the cam holder reaches the thrust receiving groove, lubricates the sliding part with the flange of the cam holder, and does not leak the lubricating oil directly into the bolt fastening work hole. Can be used.

  According to the lubricating structure of the valve mechanism according to claim 3, the oil path in the second holder of the cam holder communicates with the axial oil path and the end of the coaxial oil path, and the bolt fastening work hole of the upper bearing surface is formed. It consists of an annular oil groove that extends in the circumferential direction away from the upper position and opens the connection port toward the journal part of the camshaft. Lubricating oil is efficiently introduced into the hollow oil passage in the shaft from the annular oil groove formed extending in the circumferential direction at a position off the upper position of the hole through the introduction oil passage in the journal portion of the cam shaft.

According to the lubricating structure of the valve mechanism according to claim 4, the first holder internal oil passage and the annular oil groove of the cam holder are formed along mutually parallel surfaces perpendicular to the cam shaft, and the cam holder is connected to the cylinder head. Since the holder fixing bolt hole of the bolt coupled to the cam bearing portion is drilled between the first holder oil passage and the annular oil groove in the axial direction of the cam shaft, the first holder oil passage and the annular oil groove Can be formed close to the camshaft, and the valve mechanism can be further reduced in size and weight.
Further, since the first holder oil passage and the annular oil groove are formed along mutually parallel surfaces perpendicular to the cam shaft, the axial width of the cam holder can be made as small as possible.

  According to the lubricating structure of the valve mechanism according to claim 5, since the oil passage in the head of the cylinder head is formed at the same position as the bolt fastening work hole in the axial direction of the cam shaft, the oil passage in the head is the head. The bolt hole of the bolt and the axial direction of the camshaft are located at the same position, making it easy to drill the head oil passage communicating with the bolt hole and disposing it from the head oil passage above the bolt fastening hole. The communication with the oil path in the 1st holder provided can be comprised short.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
The internal combustion engine E according to the present embodiment is mounted on a motorcycle with a transmission M integrally provided behind the internal combustion engine E.
In the present embodiment, the front, rear, left and right coincide with the front, rear, left and right when the vehicle is used as a reference.

Referring to FIG. 1 which is a partially omitted side view of a motorcycle, a main frame 3 which is divided into two forks from a head pipe 2 of a body frame 1 and extends obliquely downward rearwardly bends a rear portion downward. The pivot plate 3p is formed, and the support shaft 4a at the lower end of the bracket 3b suspended from the position near the head pipe 2 from the center of the pair of left and right main frames 3, and the support shaft 4b at the upper and lower portions of the pivot plate 3p, The internal combustion engine E is suspended from the main frame 3 by three support shafts 4a, 4b, and 4c of 4c.
A rear fork 6 that supports a rear wheel (not shown) is pivotally supported at a front end so as to be swingable on a pivot shaft 5 installed at a center height position of the pair of left and right pivot plates 3p.

  The internal combustion engine E is a water-cooled single-cylinder four-stroke internal combustion engine. Referring to FIGS. 2 and 3, a crankcase 11 that supports the crankshaft 20 in the left-right direction that is also the vehicle width direction of the vehicle. Forms a crank chamber Cc in which the crankshaft 20 is disposed, and a transmission chamber Cm that is partitioned by a vertical partition wall 11m and accommodates the transmission M is formed behind the crank chamber Cc. An oil pan chamber Co that stores oil by being partitioned by a substantially horizontal partition wall 11o is integrally formed below.

  The single-cylinder four-stroke internal combustion engine E is connected to the cylinder block 12 having one cylinder 12a on the crank chamber Cc of the crankcase 11, and to the upper part of the cylinder block 12 by a head bolt h1 and h2 via a gasket. The engine main body is composed of a cylinder head 13 and a cylinder head cover 14 coupled to the upper part of the cylinder head 13.

The cylinder block 12, the cylinder head 13, and the cylinder head cover 14 stacked on the crankcase 11 extend upward from the crankcase 11 in a slightly tilted posture.
Thus, the upper half of the crankcase 11 of the internal combustion engine E in which the cylinder is tilted backward is the crank chamber Cc, and the latter half is the mission chamber Cm.
The oil pan chamber Co below the crank chamber Cc is a chamber inside the oil pan 15 that extends downward from the crankcase 11 and is integrally formed.

  The internal combustion engine E supported by the main frame 3 is suspended below the main frame 3 between the bracket 3b and the pivot plate 3p, and is inclined upward from the lower crankcase 11 and extends upward. , Of the cylinder head 13 and the cylinder head cover 14, the cylinder head 13 and the cylinder head cover 14 are located between the pair of left and right main frames 3, 3.

In the transmission chamber Cm of the crankcase 11, a main shaft 21 and a counter shaft 22 of the transmission M are arranged in parallel with the crankshaft 20 in the horizontal direction, and the countershaft 22 is arranged in the crankcase 11. To the left and projecting outward to form an output shaft, and a drive chain sprocket 23 is fitted to the projecting left end.
The counter shaft 22 is located near the front of the pivot shaft 5 that supports the rear fork 6, and a drive chain 24 wound around a drive chain sprocket 23 fitted to the counter shaft 22 is provided at the rear end of the rear fork 6. A chain transmission mechanism is constructed over a driven chain sprocket (not shown), and power is transmitted to the rear wheel side.

The cylinder head 13 has an intake passage 16i that is an extension of the intake port 13i obliquely upward from the front surface, and a throttle body 17 is connected between the pair of left and right main frames 3, 3 to the intake passage 16i. The upstream side of 17 intake passages is open.
An exhaust passage 16e, which is an extension of the exhaust port 13e, extends rearward substantially horizontally from the rear surface of the cylinder head 13 tilted slightly rearward, and an exhaust pipe 18 is connected to the left and right main frames 3 in the exhaust passage 16e. , 3 are connected.

  A piston pin 38 is installed between a pair of pin bosses projecting from the back surface of the piston top of the piston 30, a small end is pivotally supported by the piston pin 38, and a large end is a large end metal on the crank pin 20p of the crankshaft 20. A piston 30 and a crankshaft 20 are connected by a connecting rod 39 supported by a shaft 39a to form a crank mechanism.

The crankcase 11 is formed with a chain chamber on the left side, the left side of the crankshaft 20 passes through the chain chamber, and further penetrates the opening on the left side wall of the crankcase 11, and an oil pump is provided in a portion corresponding to the chain chamber A drive sprocket (not shown) and a drive cam chain sprocket 20cs are formed.
On the other hand, a balancer drive gear and a main drive gear (not shown) are fitted on the right side of the crankshaft 20.

  The transmission M disposed in the transmission chamber Cm behind the crank chamber Cc has a shift operated by the main shaft 21 and the counter shaft 22 provided with a main gear group 21g and a counter gear group 22g, respectively, and a shift operation mechanism. And a gear change mechanism 52 having a drum 53 and shift forks 54a, 54b, 54c (see FIG. 3).

  Therefore, the power of the internal combustion engine E is transmitted from the crankshaft 20 to the transmission M, and the output that is shifted in meshing between the main gear group 21g and the counter gear group 22g of the transmission M is transferred from the countershaft 22 to the chain transmission mechanism. Is transmitted to a chain driven sprocket (not shown), and further transmitted to a rear wheel via a secondary reduction mechanism (not shown).

  A radiator 110 is disposed in front of the internal combustion engine E as shown by a two-dot chain line in FIG. 1, and a radiator hose 111 connects an upper tank 110u of the radiator 110 and a water outlet 13we protruding forward of the cylinder head 13 to each other. A radiator hose 112 connects the lower tank 110 l of the radiator 110 and the water suction port of the water pump provided at the right front portion of the crankcase 11.

  The internal combustion engine E includes a DOHC type valve mechanism. Referring to FIG. 5, the cylinder head 13 has a combustion chamber 60 corresponding to the cylinder 12a and facing the piston 30 in the cylinder axial direction. The combustion chamber 60 has a pair of intake ports 13i that open to the left and right in the front half, and the exhaust port 13e that has a pair of openings in the left and right of the rear half. Is attached to the combustion chamber 60.

  An intake valve 62 and an exhaust valve 63, which are slidably supported by valve guides 64i and 64e integrally fitted to the cylinder head 3, are driven by a valve operating device 65 provided in the internal combustion engine E, and are thus connected to an intake port. The intake opening of 13i and the exhaust opening of the exhaust port 13e are opened and closed in synchronization with the rotation of the crankshaft 20.

  The valve operating device 65 is provided in a valve operating chamber 14v formed by the cylinder head 13 and the cylinder head cover 14, and is an intake camshaft 66 disposed in the left-right direction above the pair of left and right intake valves 62. An exhaust camshaft 67 disposed on the left and right exhaust valves 63 so as to be directed in the left-right direction is rotatably supported so as to be sandwiched between the cylinder head 13 and the cam holders 150 and 160.

  The cam lobe 66c of the intake camshaft 66 is in contact with the upper surface of the valve lifter 62l that covers the upper end of the intake valve 62 biased upward by the valve spring 62s, and the intake valve 62 is rotated by the rotation of the cam lobe 66c integrated with the intake camshaft 66. Similarly, the cam lobe 67c of the exhaust camshaft 67 is in contact with the upper surface of the valve lifter 63l that covers the upper end of the exhaust valve 63 biased upward by the valve spring 63s, and is integrated with the exhaust camshaft 67. The exhaust valve 63 is opened / closed at a required timing by the rotation of the cam lobe 67c.

  The intake camshaft 66 and the exhaust camshaft 67 are fitted with driven cam chain sprockets 66s and 67s at their left shaft ends, respectively, and the left shaft body of the two driven cam chain sprockets 66s and 67s and the crankshaft 20 A cam chain 69 is bridged between the drive cam chain sprocket 20cs formed in 20L (see FIG. 4), and the rotational power of the crankshaft 20 passes between the intake camshaft 66 and the exhaust camshaft 67 via the cam chain 69. The rotation is transmitted, and the intake cam shaft 66 and the exhaust cam shaft 67 rotate in synchronization with the crankshaft 20, and the intake valve 62 and the exhaust valve 63 are driven to open and close.

  Referring to FIG. 4, a chain guide 110 for guiding the cam chain 69 between the driven cam chain sprocket 66s of the intake camshaft 66 on the front side and the drive cam chain sprocket 20cs slightly inward (rear) is provided. The lower end of the crankcase 11 is supported by a support shaft 111 projecting forward from the crankshaft 20 and is provided so as to extend long in the upward direction.

  On the other hand, a tension slipper 115 that curbs and holds the cam chain 69 between the driven cam chain sprocket 67s of the exhaust camshaft 67 on the rear side and the drive cam chain sprocket 20cs in an arcuate shape inside (front) has a lower end at the crankcase. 11 is supported by a support shaft 116 projecting rearward from the crankshaft 20, and is provided so as to extend long.

The tension slipper 115 whose lower end is supported by the support shaft 116 and extends upward in a bow shape is pressed by a hydraulic tensioner lifter 117 provided at the rear portion of the cylinder block 12 at the center portion thereof, and the swinging force of the tension slipper 115 Thus, the cam chain 69 is pressed down and a constant tension is applied to the cam chain 69.
Further, in addition to the hydraulic tensioner lifter 117, the manual tensioner lifter 118 provided at the rear part of the cylinder head 13 presses the portion near the upper end of the tension slipper 115 appropriately. The resonance of the ripper 115 is suppressed.

Next, a lubricating system provided in the internal combustion engine E and through which lubricating oil circulates will be described.
Referring to FIG. 3, a partition wall 11o that divides the crank chamber Cc of the crankcase 11 from the lower oil pan chamber Co has a substantially arcuate shape in the lower half of the crank chamber Cc along the rotation locus of the crank web 20w. A rotor accommodating chamber 71 of the trochoidal scavenge pump 70 is formed at the rear thereof.

A suction oil passage A1 is formed between the partition wall 11o and a horizontal wall 11h extending along the partition wall 11o on the upper side of the partition wall 11o forward from the rotor storage chamber 71. The mouth A2 opens upward.
The scavenge pump 70 is in the upper part of the oil pan chamber Co, and the discharge oil port A2 is open to the upper space behind the oil pan chamber Co.

  Therefore, the oil that has returned to the crank chamber Cc partitioned by the partition walls 11o and 11m from the respective lubrication sites above the crank chamber Cc such as the crank chamber Cc and the cylinder block 12 accumulates on the partition wall 11o, and reaches the crank web. It is swung up by rotation of 20w and sprayed again on the lubrication part such as the crankshaft 20, and is sucked from the suction oil passage A1 at the center of the left and right of the crankcase 11 formed along the partition wall 11o by driving the scavenge pump 70. Then, the oil is discharged upward from the discharge oil port A2 and efficiently discharged into the upper space of the oil pan chamber Co.

A trochoid feed pump 80 is provided on the left side of the scavenge pump 70 with a rotor housing chamber 81 formed in the crankcase 11 (see FIG. 2).
The feed pump 80 and the scavenge pump 70 rotate integrally with a pump drive shaft 72 in common.

  An oil pump driven sprocket 86s is fitted to the end of the pump driving shaft 72 protruding leftward from the lid member 82, and an oil pump driving sprocket (not shown) formed on the oil pump driven sprocket 86s and the crankshaft 20 is fitted. ), An oil pump drive chain 87 is laid over, the rotational power of the crankshaft 20 is transmitted to the pump drive shaft 72, and the scavenge pump 70 and the feed pump 80 are driven.

2, passage wall 81a extends forward from the suction port of rotor accommodating chamber 81 of feed pump 80, and the upper end of oil absorption pipe 91 is connected to the front end opening thereof.
The oil absorption pipe 91 has an upper end connected to the front end opening of the passage wall 81a and extends leftward in the crankcase 11, and then bends downward and then linearly extends obliquely downward in the oil pan chamber Co. Is disposed in the vicinity of the lowest bottom surface at the front of the oil pan chamber Co.

  Therefore, the oil stored in the oil pan chamber Co of the oil pan 15 is purified by the oil strainer 90 by the drive of the feed pump 80, and is sucked up the suction oil passage B1 in the oil suction pipe 91, and the suction case in the passage wall 81a. Inhaled through oil passage B2.

  Referring to FIG. 2, a discharge case oil passage B3 is formed obliquely downward and rearward from the discharge port of the rotor accommodating chamber 81 of the feed pump 80 in the crankcase 11, and the crankcase 11 is formed from the rear portion of the discharge case oil passage B3. A discharge case oil passage B4 is formed by bending leftward along the peripheral wall.

A discharge case oil passage B5 (not shown) that communicates with the discharge case oil passage B4 at its mating surface extends to the oil filter 92 on the left side cover 40 that covers the crankcase 11 from the left. Yes.
The oil filter 92 is provided by forming a bottomed cylindrical filter housing 93 between a cylindrical portion 41 covering the left end portion of the crankshaft 20 in the crankcase 11 and a portion corresponding to the discharge case oil passage B4 at the rear end. It is done.

  An outflow case oil passage B6 for guiding oil flowing out from the oil filter 92 is formed in the filter lid member 94 covering the left end opening of the oil filter 92, and a case oil passage B7 communicating with the outflow case oil passage B6 The left side cover 40 is formed to extend into the cylindrical portion 41 that covers the left end portion of the crankshaft 20 (see FIG. 2).

Referring to FIG. 2, a case oil passage D <b> 1 extends from the cylindrical portion 41 of the left side cover 40 in the side wall of the left side cover 40 in an obliquely rearward upward direction, and then a case oil passage D <b> 2 bent in the right direction is connected to the crankcase 11. It extends to the mating surface.
The case oil passage D2 further communicates with the piston jet oil passage J2 (see FIG. 3) of the crankcase 11.

Referring to FIG. 2, a case oil passage E1 is branched upward from a connecting portion between the case oil passage D2 of the crankcase 11 and the piston jet oil passage J2.
The case oil passage E1 opens into a case oil groove E2 formed on the mating surface with the cylinder block 12, and the case oil groove E2 communicates with the cylinder oil passage E3 using the bolt hole of the left rear head bolt h2. The upper end of the cylinder oil passage E3 communicates with the head oil passage E4 formed in the cylinder head 13 at the mating surface with the cylinder head 13, and oil is supplied to the cam holder 150 from the head oil passage E4 extending upward. The required part of the device 65 is lubricated.

Referring to FIG. 5 which is a top view of the cylinder head 13, the upper end surface of the substantially rectangular peripheral wall 130 is a mating surface 130 s with the cylinder head cover 14, and the portions extended to the front and rear of the left side portion of the peripheral wall 130 are A cam chain chamber 131 is formed.
In the rectangular portion to the right of the cam chain chamber 131, a pair of left and right lifter guide holes 132i for guiding the valve lifter 62l of the intake valve 62 are formed in the front half, and lifter guide holes 132e for guiding the valve lifter 63l of the exhaust valve 63 are formed. A pair of left and right are formed in the rear half, and a spark plug mounting hole 133 for mounting the spark plug 61 is formed in the center of the four lifter guide holes 132i and 132e.

Bolt holes 134 of the head bolts h1 and h2 are formed at four oblique outer sides of each of the four lifter guide holes 132i and 132e.
The mounting seat surface 134s of the bolt hole 134 is at a position much lower than the mating surface 130s of the peripheral wall 130 (see FIG. 12).

Referring to FIG. 5, a cam bearing portion 135 having a narrow left and right width is provided so as to define a cam chain chamber 131 between the front and rear walls of the peripheral wall 130.
A cavity 139 is formed below the cam bearing portion 135, and forms a shape in which a flat plate-like column 136 integrally supports the lower surface center portion of the cam bearing portion 135 (see FIG. 12).

  A lower bearing surface 135i, which is a semicircular arc surface that supports the intake camshaft 66, is formed on the upper end surface of the cam bearing portion 135 at substantially the same front and rear position as the lifter guide hole 132i, and supports the exhaust camshaft 67. A lower bearing surface 135e is formed at substantially the same front-rear position as the lifter guide hole 132e.

On the upper end surface of the cam bearing portion 135, three portions excluding the front and rear lower bearing surfaces 135i and 135e and the front and rear end portions in the vicinity of the peripheral wall 130 form a mating surface 135s with the cam holder 150, and the mating surface 135s. Is at the same height as the upper end mating surface 130s of the peripheral wall 130.
Holder fixing bolt holes 137 are formed before and after the lower bearing surfaces 135i and 135e of the mating surface 135s.

Of the four bolt holes 134 and the mounting seat surface 134s of the head bolts h1 and h2, the left and right bolt holes 134 and the mounting seat surface 134s are lower bearings before and after the cam bearing portion 135 in a top view (FIG. 5). Bolt fastening operation holes 138i and 138e are formed in a substantially semicircular arc shape in the cam bearing portion 135 so as to cut out the lower bearing surfaces 135i and 135e. .
The bolt fastening operation holes 138i, 138e and the bolt holes 134, 134 are coaxial, and the diameter of the bolt fastening operation holes 138i, 138e is substantially the same as the diameter of the mounting seat surface 134s.
Below the bolt fastening operation holes 138i and 138e, there is a cavity 139 through which the bolt holes 134 and 134 and the mounting seat surfaces 134s and 134s are located.

Head bolts h1 and h2 screwed to the crankcase 11 project from the bolt holes 134 and 134 of the cylinder block 12 and the cylinder head 13 to the male threaded portion at the upper end through the washers w1 and w2 and the flanged nuts n1 and n1. N2 is screwed, and in this screwing operation, bolt fastening operation holes 138i and 138e of the cam bearing portion 135 that are directly above the head bolts h1 and h2 are used.
That is, the flanged nuts n1 and n2 are screwed into the head bolts h1 and h2 by fasteners inserted from above into the bolt fastening operation holes 138i and 138e.

  The cylinder block 12 and the cylinder head 13 are integrally fastened to the crankcase 11 by screwing and tightening the flanged nuts n1 and n2 by a fastener using the bolt fastening operation holes 138i and 138e.

In the cam bearing portion 135, the rear mating surface 135s bulges slightly to the right, and the connection port of the head oil passage E4 opens in the bulging mating surface 135s (see FIG. 5).
The head oil passage E4 is drilled in the same position as the left bolt hole 134 in the left-right direction.
Since the head oil passage E4 communicates with the bolt hole 134 of the left rear head bolt h2 at the mating surface of the cylinder block 12 and the cylinder head 13, the head oil passage E4 and the bolt hole 134 are in the same position in the left-right direction. The drilling operation of the head oil passage E4 is facilitated.

Another cam bearing portion 141 is formed in parallel with the cam bearing portion 135 between the left and right lifter guide holes 132i, 132i and between the lifter guide holes 132e, 132e (see FIG. 5).
Lower end bearing surfaces 141i and 141e are also formed on the front and rear positions of the upper end surface of the cam bearing portion 141 at substantially the same front and rear positions as the lifter guide holes 132i and 132e, and the three portions excluding the lower bearing surfaces 141i and 141e are the cam holder 160 and The mating surface 141s is at the same height as the upper end mating surface 130s of the peripheral wall 130.

The center mating surface 141 s of the cam bearing portion 141 has an annular shape due to the spark plug mounting hole 133.
Holder fixing bolt holes 142 are formed before and after the lower bearing surfaces 141i and 141e of the mating surface 141s.

  The intake camshaft 66 is supported on the lower bearing surfaces 135i and 141i of the left and right cam bearing portions 135 and 141 of the cylinder head 13, and the exhaust camshaft 67 is supported on the lower bearing surfaces 135e and 141e. It is sandwiched from and pivotally supported.

The cam holder 150 corresponding to the cam bearing portion 135 is connected to the wide front and rear bearing portions formed with the upper bearing surfaces 150i and 150e, which are semicircular arc surfaces, by a narrow connecting portion with reference to FIGS. Is formed.
The mating surface 150s of the cam holder 150 facing the mating surface 135s of the cam bearing portion 135 is formed in front of and behind the upper bearing surfaces 150i and 150e, and the holder fixing bolt hole 137 corresponds to the holder fixing bolt hole 137 on the mating surface 150s. 152 is drilled.

  The front and rear bearing portions of the cam holder 150 are wider than the cam bearing portion 135, and the upper bearing surfaces 150i and 150e and the mating surface 150s are larger than the lower bearing surfaces 135i and 135e and the mating surface 135s of the cam bearing portion 135 and protrude to the right side. The fixed and protruding upper bearing surfaces 150i and 150e and the mating surface 150s do not have the opposing cam bearing portion 135.

On the rear mating surface 150s of the cam holder 150, a connection port of the in-holder vertical oil passage E5 communicating with the head oil passage E4 on the cam bearing portion 135 side is opened.
A small-diameter orifice 151 is provided near the connection port of the longitudinal oil passage E5 in the holder.
The in-holder vertical oil passage E5 communicates with a first in-holder oil passage E6 that is perforated in the front-rear direction slightly above the upper bearing surfaces 150i and 150e.
The first holder oil passage E6 is formed so as to be long from the longitudinal oil passage E5 in the holder over the upper side bearing surface 150e on the exhaust side to the upper side bearing surface 150i on the intake side through the connecting portion. .

  At the uppermost part of the upper bearing surfaces 150i and 150e, axial oil grooves E7 and E7, each having one end communicating with the first holder oil passage E6 and extending to the left in the axial direction, are formed as grooves that are opened to the outside. The axial oil passages E7, E7 extend in the axial direction beyond the position of the holder fixing bolt hole 152 to the vicinity of the left side surface of the bearing portion, and at the same position, annular oil grooves E8, E8 are formed extending in the front-rear circumferential direction. Communicating with

A holder fixing bolt hole 152 is provided between the first holder oil passage E6 and the annular oil grooves E8, E8 in the axial direction of the cam shafts 66, 67.
The axial oil grooves E7, E7 and the annular oil grooves E8, E8 with respect to the first holder oil passage E6 correspond to the second holder oil passage, and both open toward the journal portion of the camshaft, In particular, the annular oil grooves E8 and E8 are open as connection ports.

  On the right side of the left-side annular oil grooves E8 and E8 on the upper bearing surfaces 150i and 150e of the cam holder 150, annular thrust receiving grooves 155 and 155 are formed in the circumferential direction. The flanges 66f and 67f formed on the intake cam shaft 66 and the exhaust cam shaft 67 are rotatably fitted to restrict movement of the intake cam shaft 66 and the exhaust cam shaft 67 in the axial direction.

A portion of the thrust receiving grooves 155 and 155 located rearward is pulled upward to form oil recovery holes 156 and 156.
The oil recovery hole 156 is a flat oblong hole that is long in the front-rear direction, and has an opening area that increases upward.

A U-shaped rib 157 is formed so as to surround the opening on the upper surface of the cam holder 150 of the oil recovery hole 156 (see FIG. 6).
Note that mounting boss portions 158 and 158 for mounting the cylinder head cover 14 protrude from the upper surface of the front and rear bearing portions of the cam holder 150.

Unlike the cam holder 150 described above, the cam holder 160 corresponding to the cam bearing portion 141 does not have a lubricating oil passage, and only has a bearing structure having a semicircular bearing surface.
However, a spark plug mounting hole is formed at the center.

Next, the intake camshaft 66 will be briefly described with reference to FIG.
The intake camshaft 66 is formed with a mounting flange 66a for mounting the driven cam chain sprocket 66s at the left end, and a journal portion 66j, an intake cam lobe 66c, a journal portion 66j, and an intake cam lobe 66c are formed in this order from the mounting flange 66a. It reaches the right end flange 66b.
An oil supply groove 66v and a thrust receiving flange 66f are formed on the left journal 66j on the left and right in an annular shape in the circumferential direction.

The intake camshaft 66 has a cylindrical shape, the openings on both sides are closed with seal plugs 66p, 66p, and the inside is an in-shaft hollow oil passage F. The oil supply groove 66v is introduced oil communicating with the in-shaft hollow oil passage F A plurality of passages 66vh are perforated in the circumferential direction, and outlet oil passages 66jh, 66ch, 66ch communicating with the hollow oil passage F in the shaft are respectively perforated in the right journal portion 66j and the left and right intake cam lobes 66c, 66c. Yes.
The exhaust camshaft 67 has substantially the same structure, and the exhaust camshaft 67 is equipped with an auto decompression mechanism 180 (which can be a manual decompression mechanism) that presses the exhaust valve 63 to reduce the pressure in the combustion chamber at the start. It has been.

  The journal portions 66j and 66j of the intake camshaft 66 are placed on the lower bearing surfaces 135i and 141i of the left and right cam bearing portions 135 and 141 of the cylinder head 13, and the exhaust camshaft 67 journal is placed on the lower bearing surfaces 135e and 141e. The parts 67j and 67j are placed, the cam holder 150 is overlapped on the left cam bearing part 135, the bolt 170 is passed through the four holder fixing bolt holes 152, and screwed into the holder fixing bolt holes 137, and is sucked by the upper bearing surfaces 150i and 150e. The left journal portion 66j of the camshaft 66 and the left journal portion 67j of the exhaust camshaft 67 are rotatably held. Similarly, the cam holder 160 is overlapped on the right cam bearing portion 141 and the right journal portion 66j of the intake camshaft 66 and the exhaust camshaft The right journal part 67j of 67 is clamped rotatably.

11 to 13 show a state in which the intake cam shaft 66 and the exhaust cam shaft 67 are rotatably supported by the left and right cam bearing portions 135 and 141 of the cylinder head 13 sandwiched from above by the cam holders 150 and 160, respectively. .
The left journal portion 66j of the intake camshaft 66 supported by the cam holder 150 and the left journal portion 67j of the exhaust camshaft 67 are in sliding contact with the upper bearing surfaces 150i and 150e of the cam holders 150 and 160, respectively. The lower half arc surface has a right end portion that is in sliding contact with the lower bearing surfaces 135e and 141e of the cam bearing portion 135, and the other portions are exposed facing the bolt fastening operation holes 138i and 138e (see FIG. 13).

  The left journal portion 66j of the intake cam shaft 66 and the right flanges 66f and 67f of the left journal portion 67j of the exhaust cam shaft 67 are rotatably fitted in the semicircular arc shaped thrust receiving grooves 155 and 155 of the cam holder 150. Movement of the intake cam shaft 66 and the exhaust cam shaft 67 in the axial direction is restricted.

  The vertical oil passage E5 in the holder of the cam holder 150 is connected to the head oil passage E4 on the cam bearing portion 135 side of the cylinder head 13, and the oil rising up the head oil passage E4 is the vertical oil passage E5 in the holder of the cam holder 150. Is further raised through the orifice 151, moved to the first holder oil passage E6, and pumped forward.

The oil supply grooves 66v and 67v of the left journal portions 66j and 67j of the intake camshaft 66 and the exhaust camshaft 67 are opposed to the semicircular annular oil grooves E8 and E8 of the cam holder 150, respectively.
Therefore, the oil that has reached the annular oil grooves E8 and E8 from the first holder oil passage E6 of the cam holder 150 through the axial oil grooves E7 and E7, and the intake camshaft 66 and the exhaust cam facing the annular oil grooves E8 and E8. The oil is introduced into the in-shaft hollow oil passages F and F from the oil supply grooves 66v and 67v of the shaft 67 through the inlet oil ports 66vh and 67vh.

The left journal portions 66j and 67j of the intake camshaft 66 and the exhaust camshaft 67 are lubricated by the oil in the axial oil groove E7 and the annular oil groove E8, and the oil in the hollow oil passage F in the intake camshaft 66 is derived oil. Derived from the port 66jh and lubricates the right journal 66j of the intake camshaft 66, the oil derived from the derived oil ports 66ch and 66ch lubricates the surfaces of the intake cam lobes 66c and 66c.
The right journal portion of the exhaust camshaft 67 and the exhaust cam lobe are also supplied with oil in the in-shaft hollow oil passage F and lubricated.

  The cylinder head 13 is provided with head bolts h1 and h2 at positions overlapping the cam holder 150 in the vertical direction in order to reduce the size, and bolt fastening operation holes 138i and 138e for fastening the head bolts h1 and h2 are provided. A structure in which a part of the lower bearing surfaces 135i and 135e of the cam bearing portion 135 is cut out is formed, and the cylinder head 13 is reduced in size.

In the cam holder 150 attached to the cam bearing portion 135, the upper bearing surfaces 150i and 150e are located above the bolt fastening operation holes 138i and 138e formed in the cam bearing portion 135 and extend in the front-rear direction in the cam holder 150. The first holder oil passage E6 is disposed above the bolt fastening operation holes 138i and 138e.
The axial oil grooves E7, E7 extending leftward from the first holder internal oil passage E6 have their left ends disengaged from the positions above the bolt fastening work holes 138i, 138e, and the annular oil grooves E8, E8 are also bolt fastening work holes 138i, It is off from the upper position of 138e.

  Accordingly, the axial oil grooves E7 and E7 are closed at the lower open portions by the left journal portions 66j and 67j of the intake camshaft 66 and the exhaust camshaft 67, and the oil directly enters the lower bolt fastening operation holes 138i and 138e. Leakage is restrained and sent to the semicircular arc-shaped annular oil grooves E8, E8, where the annular oil grooves E8, E8 are the upper semicircular portions of the oil supply grooves 66v, 67v over the entire circumference of the left journal portions 66j, 67j. The lower semicircular arc portions of the oil supply grooves 66v and 67v are closed by the lower bearing surfaces 135i and 135e of the cam bearing portion 135, so that the oil can be leaked through the inlet oil ports 66vh and 67vh without leaking except for lubrication. The oil is sufficiently introduced into the in-shaft hollow oil passages F and F, and the introduced oil is supplied from the in-shaft hollow oil passages F and F to the right journal portion and the sliding contact portion of the cam lobe and can be well lubricated.

  That is, despite the configuration in which the head bolts h1 and h2 are arranged at positions that overlap the cam holder 150 in the vertical direction to reduce the size of the cylinder head 13, the lubrication structure of the valve operating mechanism 65 is the same as that of the intake camshaft 66. The required lubricating portion of the exhaust camshaft 67 can be well lubricated.

  Thrust receiving grooves 155, 155 are formed in the circumferential direction above the bolt fastening operation holes 138i, 138e on the upper bearing surfaces 150i, 150e of the cam holder 150, and journals of the cam shafts 66, 67 are formed in the thrust receiving grooves 155, 155. The flanges 66f and 67f formed on the portions 66j and 67j are slidably fitted to restrict movement of the cam shafts 66 and 67 in the axial direction.

  Since the oil collection holes 156 and 156 are formed through the thrust receiving grooves 155 and 155 formed in the upper bearing surfaces 150i and 150e which are the lower surfaces of the cam holder 150, the cam shafts 66 and 67 Of the oil that has been scattered with the rotation and dropped onto the upper surface of the cam holder 150, the oil that has entered the oil recovery holes 156, 156 opened above the cam holder 150 reaches the thrust receiving grooves 155, 155, and the flange 66f, The sliding portion with 67f can be lubricated and oil can be used effectively without directly leaking into the bolt fastening operation holes 138i and 138e.

Since the upper surface of the cam holder 150 fixed to the cam bearing portion 135 of the cylinder head 13 in a slightly tilted posture is also inclined so that the rear is lowered, the oil that has fallen on the upper surface of the cam holder 150 tends to flow backward. .
A U-shaped rib 157 is formed on the upper surface of the cam holder 150 so as to surround the opening of the oil recovery hole 156 so that the oil that falls on the upper surface of the cam holder 150 and flows backward is forward. The U-shaped ribs 157 with the holes opened can be efficiently collected and recovered in the oil recovery hole 156.

  Since the first holder oil passage E6 and the annular oil groove E8 of the cam holder 150 are formed along mutually parallel surfaces perpendicular to the cam shafts 66 and 67, the axial width of the cam holder 150 should be made as small as possible. Can do.

  First holder internal oil passage formed with holder fixing bolt holes 137 and 152 for connecting the cam holder 150 to the cam bearing portion 135 of the cylinder head 13 along surfaces parallel to each other in the axial direction of the cam shafts 66 and 67. Since it is drilled between E6 and the annular oil groove E8, the holder fixing bolt holes 137 and 152 can be formed close to the camshaft between the first holder oil passage E6 and the annular oil groove E8. The valve operating mechanism can be further reduced in size and weight.

  The in-head oil passage E4 of the cylinder head 13 is formed at the same position as the bolt hole 134 of the head bolt h2 in the axial direction of the cam shafts 66 and 67. That is, the in-head oil passage E4 is connected to the bolt hole 134 of the head bolt h2 and the cam. The drilling of the oil passage E4 in the head that is in the same position in the axial direction of the shafts 66 and 67 and communicates with the bolt hole 134 is easy, and the bolt fastening work holes 138i and 138e are connected to the oil passage E4 in the head. The in-holder vertical oil passage E5, which is a communication passage to the first holder oil passage E6 disposed at the upper position, can be configured to be short.

In addition, an oil return oil passage 190 in the head is opened at the right rear portion of the upper surface in the head of the cylinder head 13 tilted backward, and the oil return oil passage 190 in the head perforates the cylinder head 13 and the cylinder block 12. The oil collected in the rear part of the rearwardly tilted cylinder head 13 is guided to the hydraulic tensioner lifter 117 provided in the cylinder block 12.
Since the hydraulic tensioner lifter 117 is also provided on the left side of the cylinder block 12 but on the rear side, the oil return oil passage 190 in the head that opens to the right rear portion of the upper surface inside the head can be formed concentrated on the rear portion. It can be shortened and simplified.

1 is a partial side view of a motorcycle on which an internal combustion engine according to an embodiment of the present invention is partially omitted. It is a left view of an internal combustion engine. FIG. 3 is a left sectional view taken along a mating surface of a crankcase of an internal combustion engine. It is the left view which removed the left side cover of the internal combustion engine. It is a top view of a cylinder head. It is a top view of a cam holder. It is the same bottom view. It is the VIII-VIII sectional view taken on the line of FIG. It is the IX-IX sectional view taken on the line of FIG. It is the side view made into the partial cross section of the intake cam shaft. It is a top view which shows the valve operating mechanism comprised by the cylinder head. It is the XII-XII sectional view taken on the line of FIG. It is the XIII-XIII sectional view taken on the line of FIG.

Explanation of symbols

E3 ... Cylinder oil passage, E4 ... Head oil passage, E5 ... Vertical oil passage in the holder, E6 ... First oil passage in the holder, E7 ... Axial oil groove, E8 ... Annular oil groove, F ... Hollow oil passage in the shaft,
E ... Internal combustion engine, M ... Transmission, h1, h2 ... Head bolt,
11 ... Crank case, 12 ... Cylinder block, 13 ... Cylinder head, 14 ... Cylinder head cover, 15 ... Oil pan, 20 ... Crank shaft,
66 ... intake camshaft, 66c ... cam lobe, 66f ... thrust receiving flange, 66j ... journal section, 66v ... oil supply groove, 66vh ... inlet oil port, 66jh, 66ch, 66ch ... outlet oil port, 67 ... exhaust camshaft, 67v ... Lubrication groove, 67vh ... Introduction oil port,
134 ... Bolt hole, 134s ... Mounting seat surface, 135 ... Cam bearing, 135i, 135e ... Lower bearing surface, 135s ... Mating surface, 137 ... Holder fixing bolt hole, 138i, 138e ... Bolt fastening work hole, 139 ... Hollow , 141 ... cam bearing part, 141i, 141e ... lower bearing surface, 142 ... holder fixing bolt hole,
150 ... cam holder, 150i, 150e ... upper bearing surface, 150s ... mating surface, 151 ... orifice, 152 ... holder fixing bolt hole, 155 ... thrust receiving groove, 156 ... oil recovery hole, 157 ... rib, 158 ... mounting boss, 160 ... Cam holder.

Claims (5)

The cylinder block and the cylinder head are sequentially stacked on the crankcase and fastened by a head bolt to constitute an internal combustion engine.
A cam bearing portion having a lower bearing surface formed on the cylinder head is formed,
A valve operating valve coupled to the cam bearing portion so that a cam holder having an upper bearing surface facing the lower bearing surface of the cam bearing portion is rotatably supported with the cam shaft interposed between the bearing surfaces. In the mechanism,
A bolt fastening work hole for the head bolt is formed in a part of the lower bearing surface,
In the cylinder head, an oil passage in the head that opens a connection port is formed on a coupling surface of the cam bearing portion with the cam holder,
A first holder oil passage that communicates with the connection port of the oil passage in the head to the cam holder and is disposed at a position above the bolt fastening work hole, and an axial direction of the camshaft from the oil passage in the first holder. A second holder oil passage that extends and opens a connection port at a position that is at least above the bolt fastening work hole on the upper bearing surface;
A valve operating system characterized in that an introduction oil passage formed through a journal portion in a radial direction from an in-shaft hollow oil passage in the cam shaft communicates with a connection port of the second holder internal oil passage of the cam holder. Lubrication structure of the mechanism. A flange formed on the journal portion of the cam shaft is slidably fitted into a thrust receiving groove formed in the circumferential direction above the bolt fastening work hole on the lower bearing surface, and the cam shaft Axial movement is restricted,
2. The lubrication structure for a valve operating mechanism according to claim 1, wherein the cam holder penetrates upward from the thrust receiving groove to form an oil recovery hole.   The oil passage in the second holder of the cam holder communicates with an axial oil passage extending in an axial direction from the oil passage in the first holder and an end portion of the coaxial oil passage, and the bolt fastening work hole in the upper bearing surface. 3. The motion according to claim 1, further comprising an annular oil groove that extends in a circumferential direction to a position deviated from an upper position of the cam shaft and opens a connection port toward a journal portion of the cam shaft. Lubrication structure of valve mechanism. The first holder oil passage and the annular oil groove of the cam holder are formed along mutually parallel surfaces perpendicular to the cam shaft;
A holder fixing bolt hole of a bolt that couples the cam holder to the cam bearing portion of the cylinder head is drilled between the oil path in the first holder and the annular oil groove in the axial direction of the cam shaft. The lubricating structure for a valve operating mechanism according to claim 3.   The oil path in the head of the cylinder head is formed at the same position as the bolt fastening work hole in the axial direction of the camshaft. Lubrication structure of the valve mechanism.

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