JP5998832B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine.

  There is known an internal combustion engine that includes a main lubricating oil passage connected to the discharge side of an oil pump and a cylinder-side oil passage that guides the lubricating oil to a lubricating portion of a cylinder head. The main lubricating oil passage includes a first oil supply passage that guides lubricating oil to the cylinder-side oil passage and a second oil supply passage that guides lubricating oil to an oil passage other than the cylinder-side oil passage. The first oil supply path and the second oil supply path branch off at the coupling surface of the crankcase. An orifice that defines the flow rate of the lubricating oil in the first oil supply passage is incorporated into the cylinder block from the coupling surface side of the cylinder block (see, for example, Patent Document 1).

JP 2007-170314 A

  In the conventional engine, the flow rate of the lubricating oil in the first oil supply passage is defined by an orifice provided in the cylinder block, and the flow rate of the lubricating oil in the second oil supply passage is defined as the remaining amount.

  By the way, if the flow rate of the lubricating oil supplied to the cylinder block is compared with the flow rate of the lubricating oil supplied to other than the cylinder block, the flow rate of the lubricating oil supplied to the cylinder block is considerably small. Specifically, since the conventional engine requires an orifice having a small orifice diameter, individual members for forming the orifice are prepared, and fine holes are drilled and incorporated into the cylinder block.

  Thus, preparing the orifices individually and incorporating them into the cylinder block or the like complicates the structure of the engine and increases the number of parts and the number of assembly steps.

  Accordingly, an object of the present invention is to provide an internal combustion engine capable of forming a throttle mechanism that adjusts the flow rate of lubricating oil integrally with a crankcase without requiring individual members.

In order to solve the above problems, an internal combustion engine according to the present invention includes a crankcase having a crank chamber and a transmission chamber, a crankshaft accommodated in the crank chamber, a transmission device accommodated in the transmission chamber, A cylinder block coupled to a crankcase; a cylinder head joined to the cylinder block; a valve mechanism accommodated in the cylinder head; an oil pump provided in the crankcase for discharging lubricating oil; A main lubricating oil passage fluidly connected to a discharge side of an oil pump; a first oil supply passage branched from the main lubricating oil passage to guide the lubricating oil to the cylinder head and lubricate the valve mechanism; and A second branching from the main lubricating oil passage to guide the lubricating oil to the transmission chamber and lubricate the transmission Connecting an oil passage, and a third oil supply passage for lubricating said crankshaft guiding the lubricating oil to the crank chamber is branched from the main lubricating oil passage, is formed in the crankcase upstream to the main lubricating oil passage And an oil passage portion for branching the first oil supply passage and the second oil supply passage on the downstream side, and provided in the oil passage portion to branch from the main lubricating oil passage to the first oil supply passage and the second oil supply passage. A throttle mechanism that collectively restricts the flow rate of the lubricating oil, the throttle mechanism being formed integrally with the crankcase, and formed in the partition and downstream from the upstream side of the oil passage portion. and an orifice hole that defines the flow rate of lubricating oil flowing to the side, that have a.

  ADVANTAGE OF THE INVENTION According to this invention, the internal combustion engine which can form the throttle mechanism which adjusts the flow volume of lubricating oil integrally with a crankcase, without requiring a separate member can be provided.

1 is a left side view showing a motorcycle to which an internal combustion engine according to an embodiment of the present invention is applied. The perspective view which shows the engine which concerns on embodiment of this invention from the right rear. The disassembled perspective view which shows the crankcase of the engine which concerns on embodiment of this invention. The block diagram which shows the lubrication structure of the engine which concerns on embodiment of this invention. The right view which shows the engine which concerns on embodiment of this invention. Sectional drawing which shows the crankshaft oiling path of the engine which concerns on embodiment of this invention. 1 is a cross-sectional view showing an engine throttle mechanism according to an embodiment of the present invention. The partial top view which shows the principal part of the engine which concerns on embodiment of this invention.

  An embodiment of an engine according to the present invention will be described with reference to FIGS.

  FIG. 1 is a left side view showing a motorcycle to which an internal combustion engine according to an embodiment of the present invention is applied.

  In the present embodiment, expressions of front and rear, top and bottom, and left and right are based on the occupant of the motorcycle 1.

  As shown in FIG. 1, a motorcycle 1 according to the present embodiment is disposed in front of a vehicle body frame 2 that extends in the front and rear of the vehicle, an engine 3 that is an internal combustion engine mounted on the vehicle body frame 2, and the vehicle body frame 2. A steering mechanism 5 that can be steered in the left-right direction of the vehicle, a front wheel 6 that is disposed in front of the vehicle body frame 2 and is rotatably supported by the steering mechanism 5, and a vehicle wheel that is disposed behind the vehicle body frame 2 in the vertical direction of the vehicle. A rear wheel suspension device 7 that is supported so as to be freely swingable, and a rear wheel 9 that is disposed behind the vehicle body frame 2 and is rotatably supported by the rear wheel suspension device 7.

  The body frame 2 is connected to a head pipe 11 disposed in the foremost part of the body frame 2, a pair of left and right main frames (not shown) extending obliquely rearward and downward from the head pipe 11, and a rear end portion of the main frame. A pivot frame (not shown) that hangs downward, a down tube 15 that extends downward from the head pipe 11, bends backward to protect the lower side of the engine 3 and is connected to the lower end of the pivot frame, and the main frame 12. A rear frame (not shown) connected to the rear end portion and extending rearward.

  The main frame also serves as a tank rail, supports the fuel tank 21 disposed above, and mounts the engine 3 below the fuel tank 21.

The pivot frame includes a pivot shaft (not shown). The pivot shaft is installed substantially at the lower center of the pair of left and right pivot frames and supports the swing arm 23 so as to be swingable in the vertical direction. The rear frame is a pair of left and right seat rails extending rearward from the rear end of the main frame ( (Not shown) and a pair of left and right seat pillar tubes that extend obliquely rearward and upward from the pivot frame and are connected to the rear portion of the seat rail (not shown). The seat rail supports the seat 27 and a rear fender 28 that extends rearward of the seat 27 and covers the rear wheel 9.

  The engine 3 is a four-cycle internal combustion engine, for example, and is mounted between the main frame 12 and the down tube 15 with a center line of a cylinder (not shown) directed in the vertical direction of the motorcycle 1. The engine 3 is connected to the exhaust muffler 29 via an exhaust pipe (not shown) that extends rearward of the vehicle body and exhausts the exhaust gas of the engine 3.

  The steering mechanism 5 is steered left and right around the head pipe 11. The steering mechanism 5 includes a pair of left and right front forks 31, a front fender 32 provided on the front fork 31 and covering the front wheel 6, and a handle 33 provided on the top of the steering mechanism 5.

  The front fork 31 includes a suspension mechanism (not shown) to ground the front wheel 6.

  The front wheel 6 is rotatably supported by front wheel shafts (not shown) installed on the lower ends of the pair of left and right front forks 31.

  The rear wheel suspension device 7 swings around the pivot shaft. The rear wheel suspension device 7 includes a swing arm 23 extending from the front end portion supported by the pivot shaft to the rear of the vehicle, and a rear cushion unit 35 installed between the swing arm 23 and the vehicle body frame 2.

  The rear wheel 9 is rotatably supported by a rear wheel shaft (not shown) provided at the rear end portion of the swing arm 23. The rear wheel 9 includes a driven sprocket 36. The rear wheel 9 obtains driving force from the engine 3 by a drive chain (not shown) wound around a driven sprocket (not shown).

  The motorcycle 1 further includes a frame cover 39 that covers the left and right sides of the space below the seat 27.

  Next, the engine 3 according to the present embodiment will be described in detail.

  FIG. 2 is a perspective view showing the engine according to the embodiment of the present invention from the right rear side.

  As shown in FIG. 2, the engine 3 according to the present embodiment is a four-cycle single cylinder engine, and includes a crankcase 41, a cylinder block 42, a cylinder head 43, and a head cover 45.

  The crankcase 41 can be divided into left and right. The crankcase 41 includes a pair of left and right crankcase halves 48 and 51 that are combined at a coupling surface 47 that is substantially orthogonal to the rotation center line C of the crankshaft 46. The crankcase 41 includes a left crankcase cover 49 as a left side wall provided on the left side of the left crankcase half 48 and a right crankcase cover 52 as a right side wall provided on the right side of the right crankcase half 51. .

  The left crankcase cover 49 is a magneto cover, and the right crankcase cover 52 is a clutch cover.

  The cylinder block 42 is coupled to the upper half of the upper surface of the crankcase 41 in a substantially upright state. The cylinder block 42 has a cylindrical cylinder bore 55 that houses a piston 53 that is slidable in a substantially vertical direction.

  The cylinder head 43 is coupled to the upper surface of the cylinder block 42 to block the upper side of the cylinder bore 55 and partitions a combustion chamber (not shown) between the piston 53 and the cylinder head 43. The piston 53 reciprocates by combustion of the air-fuel mixture that occurs periodically in the combustion chamber.

  The cylinder block 42 and the cylinder head 43 are fastened to the crankcase 41 with bolts 56.

  The head cover 45 is coupled to the upper surface of the cylinder head 43.

  FIG. 3 is an exploded perspective view showing a crankcase of the engine according to the embodiment of the present invention.

As shown in FIG. 3, the crankcase 41 of the engine 3 according to this embodiment includes a left crankcase half 48, a right crankcase half 51, a left crankcase cover 49, a right crankcase cover 52, Is provided. The crankcase 41 includes a crank chamber 57 and a transmission chamber 58. The left crankcase half 48 and the right crankcase half 51 are connected to each other by a coupling surface 47 that is substantially orthogonal to the rotation center line C of the crankshaft 46. They are combined and can be divided in the direction of the rotation center line C of the crankshaft 46. The left crankcase half 48 and the right crankcase half 51 partition a crank chamber 57 that houses the crankshaft 46 and a transmission chamber 58 that houses the transmission 59. The crank chamber 57 is disposed on the front side of the engine 3, and the transmission chamber 58 is disposed on the rear side of the engine 3. That is, the crank chamber 57 and the transmission chamber 58 are adjacent to the front and rear of the engine 3.

  The right crankcase half 51 and the right crankcase cover 52 partition the clutch chamber 61. A coupling surface 62 (second coupling surface) between the right crankcase half 51 and the right crankcase cover 52 is disposed in parallel to a coupling surface 47 between the left crankcase half 48 and the right crankcase half 51. The

  The left crankcase half 48 and the left crankcase cover 49 partition the magnet chamber 63. The magnet chamber 63 is connected to the crank chamber 57. The coupling surface between the left crankcase half 48 and the left crankcase cover 49 is also arranged in parallel to the coupling surface 47 between the left crankcase half 48 and the right crankcase half 51.

  The crankshaft 46 passes through the clutch chamber 61, the crank chamber 57 and the magnet chamber 63. The crankshaft 46 is rotatably supported by the left crankcase half 48 and the right crankcase half 51.

  FIG. 4 is a block diagram showing an engine lubrication structure according to an embodiment of the present invention.

  As shown in FIG. 4, the engine 3 according to this embodiment includes a crankshaft 46 housed in a crank chamber 57, a piston 53 in a cylinder bore 55, a transmission 59 housed in a transmission chamber 58, and valves of the cylinder head 43. A lubrication structure 67 that circulates lubricating oil to a valve operating mechanism 66 accommodated in the chamber 65 is provided.

  The lubricating structure 67 includes an oil pump 68, a main lubricating oil passage 69, a cylinder-side oil supply passage 71 (first oil supply passage), a transmission-side oil supply passage 72 (second oil supply passage), and a crankshaft oil supply passage 73 ( A third oil supply passage), a piston oil supply passage 75 (fourth oil supply passage), and a throttle mechanism 76.

  The oil pump 68 is provided in the crankcase 41 and pumps up and discharges the lubricating oil in the clutch chamber 61.

  The main lubricating oil passage 69 is fluidly connected to the discharge side of the oil pump 68.

  The cylinder-side oil supply passage 71 is branched from the main lubricant passage 69 and guides the lubricant to the cylinder head 43 to lubricate the valve mechanism 66. Specifically, the cylinder side oil supply passage 71 supplies lubricating oil to journal bearings (not shown) of the intake side camshaft 77 and the exhaust side camshaft 78.

  The transmission side oil supply passage 72 is branched from the main lubricating oil passage 69 and guides the lubricating oil to the transmission chamber 58 to lubricate the transmission 59. Specifically, the transmission side oil supply passage 72 supplies lubricating oil to a journal bearing (not shown) of the transmission 59.

  The crankshaft oil supply passage 73 is branched from the main lubricant oil passage 69 to guide and lubricate the lubricant. Specifically, the crankshaft oil supply passage 73 supplies lubricating oil to a journal bearing (not shown) or the like via an in-shaft oil supply passage 79 in the crankshaft 46.

  The piston oil supply path 75 guides the lubricating oil to the piston jet 81 that jets the lubricating oil toward the bottom of the piston 53 and lubricates the piston 53.

  The throttle mechanism 76 collectively limits the flow rate of the lubricating oil that branches from the main lubricating oil passage 69 to the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72.

  The lubricating oil supplied to each part of the engine 3 such as the valve operating mechanism 66, the transmission 59, the crankshaft 46, the piston 53, etc. returns to the clutch chamber 61 via the bottom of the crank chamber 57, and again by the oil pump 68. Circulated.

  FIG. 5 is a right side view showing the engine according to the embodiment of the present invention.

  FIG. 5 is shown with the right crankcase cover 52 removed.

  As shown in FIG. 5, the engine 3 according to this embodiment includes an oil pump 68 inside the right crankcase cover 52. The oil pump 68 is driven by the rotation of the crankshaft 46.

  The right crankcase half 51 includes a main lubricating oil passage 69 through which lubricating oil flows from a discharge port 82 connected to an oil pump 68. The oil pump 68 is driven along with the operation of the engine 3 and discharges the lubricating oil pumped up from the bottom of the clutch chamber 61 to the main lubricating oil passage 69.

  The main lubricant passage 69 extends over the right crankcase half 51 and the right crankcase cover 52. The main lubricating oil passage 69 is a combination of grooves formed by casting on the coupling surface 62 of the right crankcase half 51 and the right crankcase cover 52. The main lubricating oil passage 69 has a larger cross-sectional area than downstream oil passages such as the cylinder-side oil passage 71, the transmission-side oil passage 72, the crankshaft oil passage 73, the piston oil passage 75, and the like. Functioning as a storage chamber for temporarily storing the oil, to reduce fluctuations in the amount of lubricating oil discharged from the oil pump 68, and to stabilize the supply of lubricating oil in the downstream oil passage.

  The main lubricating oil passage 69 may be formed by casting in either the right crankcase half 51 or the right crankcase cover 52.

  The crankshaft oil supply passage 73 is provided in the right crankcase cover 52. Crankshaft oil supply passage 73 has an upstream end connected to main lubricant passage 69. That is, the main lubricating oil passage 69 branches into the crankshaft oil supply passage 73, and the lubricating oil in the main lubricating oil passage 69 is diverted to the crankshaft oil supply passage 73.

  The piston oil supply passage 75 is provided in the right crankcase half 51. Piston oil supply passage 75 has an upstream end connected to main lubricant oil passage 69. That is, the main lubricating oil passage 69 branches into the piston oil supply passage 75, and the lubricating oil in the main lubricating oil passage 69 is also branched into the piston oil supply passage 75.

  The throttle mechanism 76 is provided in the right crankcase half 51. The throttle mechanism 76 is connected to the downstream end of the main lubricant passage 69. That is, the main lubricating oil passage 69 branches to the throttle mechanism 76, and the lubricating oil in the main lubricating oil passage 69 is also diverted to the throttle mechanism 76. The diverted lubricating oil is supplied to the cylinder side oil supply passage 71 and the transmission side oil supply passage 72 through the throttle mechanism 76.

  Each of the crankshaft oil supply passage 73 and the piston oil supply passage 75 branches off from the main lubricant oil passage 69 in the middle until the lubricant in the main lubricant passage 69 reaches the throttle mechanism 76.

  6 is a cross-sectional view showing the crankshaft oil supply passage of the engine according to the embodiment of the present invention, taken along line VI-VI in FIG.

  As shown in FIG. 6, the crankshaft oil supply passage 73 of the engine 3 according to the present embodiment passes through the wall of the right crankcase cover 52, and is one end portion (here, the right end portion) of the crankshaft 46. And fluidly connected to an in-shaft oil supply passage 79 provided in the crankshaft 46. The crankshaft oil supply passage 73 and the in-shaft oil supply passage 79 are relatively rotatably connected.

  FIG. 7 is a cross-sectional view showing the throttle mechanism of the engine according to the embodiment of the present invention, taken along the line VII-VII in FIG.

  As shown in FIG. 7, the throttle mechanism 76 of the engine 3 according to this embodiment is a so-called orifice. The throttle mechanism 76 linearly extends in a direction orthogonal to the coupling surface 47 between the left crankcase half 48 and the right crankcase half 51 and extends from the main lubricating oil passage 69 to the cylinder side oil supply passage 71 and the transmission side oil supply passage. 72 is provided in a straight oil passage 83 for branching 72. The throttle mechanism 76 has an orifice hole 85 that defines the flow rate of the flowing lubricating oil.

  The throttle mechanism 76 is closer to the coupling surface 47 than the bolt hole 86 that fastens the bolt 56 that fastens the cylinder block 42 to the crankcase 41, and is connected to a boss 87 having the bolt hole 86.

  The diameter of the orifice hole 85 is smaller than the diameter of the straight oil passage portion 83.

  The straight oil passage 83 is formed by casting on the upstream large diameter portion 88 formed by casting on the coupling surface 62 side of the right crankcase half 51 and by casting on the coupling surface 47 side of the right crankcase half 51. And a downstream large-diameter portion 89. The upstream large-diameter portion 88 and the downstream large-diameter portion 89 are disposed on substantially the same line and face each other with the throttle mechanism 76 interposed therebetween.

  The upstream large diameter portion 88 has an upstream end connected to the main lubricating oil passage 69. That is, the main lubricating oil passage 69 is branched into the straight oil passage portion 83, and the lubricating oil in the main lubricating oil passage 69 is also branched into the straight oil passage portion 83. The lubricating oil in the upstream large-diameter portion 88 flows into the downstream large-diameter portion 89 after the flow rate is determined by the throttle mechanism 76.

  The orifice hole 85 is formed by drilling using a drill after integrally forming a partition wall 91 in which the upstream large diameter portion 88 and the downstream large diameter portion 89 face each other in the right crankcase half 51 by casting.

  FIG. 8 is a partial plan view showing a main part of the engine according to the embodiment of the present invention. FIG. 8 is shown with the cylinder block 42 removed.

  As shown in FIG. 8, the throttle mechanism 76 of the engine 3 according to the present embodiment overlaps the coupling surface 92 between the cylinder block 42 and the crankcase 41 when viewed in the direction of the center line of the cylinder bore 55.

  The cylinder-side oil supply passage 71 has an upstream end that is provided in the right crankcase cover 52 and connected to the downstream large-diameter portion 89 of the linear oil passage portion 83. That is, the straight oil passage 83 and thus the main lubricating oil passage 69 branch to the cylinder-side oil supply passage 71, and the lubricating oil in the main lubricating oil passage 69 is divided into the cylinder-side oil supply passage 71. The cylinder-side oil supply passage 71 reaches the valve operating mechanism 66 through the cylinder block 42 and the cylinder head 43. A portion of the cylinder-side oil supply passage 71 provided on the right crankcase cover 52 is formed by drilling from the coupling surface 92 of the crankcase 41 using a drill.

  The lubricating oil that has passed through the cylinder-side oil supply passage 71 and lubricated the valve operating mechanism 66 returns to the crankcase 41 through the cam chain tunnel 93 provided on the side of the cylinder block 42.

  The transmission side oil supply passage 72 has an upstream end connected to the downstream end of the downstream large diameter portion 89 of the linear oil passage portion 83. The transmission side oil supply passage 72 is formed by casting on the coupling surface 47 side of the right crankcase half 51. The transmission side oil supply passage 72 extends to the rear side of the engine 3 along the coupling surface 47 between the left crankcase half 48 and the right crankcase half 51 and supplies lubricating oil to the transmission 59. Note that the transmission-side oil supply passage 72 may be formed by casting on the coupling surface 47 side of the left crankcase half 48.

  Incidentally, the flow rate of the lubricating oil required for the cylinder side oil supply passage 71 and the transmission side oil supply passage 72 is very small compared to the flow rate of the lubricating oil required for the piston oil supply passage 75 and the crankshaft oil supply passage 73. On the other hand, when the orifice hole 85 is drilled by drilling using a drill, the minimum opening diameter of the orifice diameter depends on the diameter of the drill. Therefore, when the orifice diameter when the flow rates of the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72 are individually controlled is smaller than the minimum dimension of the drill diameter, the orifice has a theoretically required opening diameter. It will be larger than that, and excess lubricating oil will be supplied.

  Therefore, the engine 3 according to the present embodiment collectively limits and regulates the flow rate of the lubricating oil that branches from the main lubricating oil passage 69 to the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72 by the throttle mechanism 76. . Accordingly, the engine 3 according to the present embodiment can define the total flow rate supplied to the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72 by the throttle mechanism 76, and the cylinder-side oil supply passage 71 and the transmission device can be specified. The opening diameter (orifice diameter) of the orifice hole 85 can be defined relatively large as compared with the case where the flow rate of the side oil supply passage 72 is individually regulated. Thereby, the engine 3 according to the present embodiment can optimize the flow rate of the lubricating oil that branches from the main lubricating oil passage 69 to the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72. In addition, the engine 3 according to the present embodiment can be integrally formed with a throttle mechanism 76 in the crankcase 41, unlike a conventional engine in which an orifice is prepared by a separate member in order to reduce the orifice diameter. In addition, it is possible to provide an orifice hole 85 having a diameter larger than that of a conventional engine directly in the crankcase 41 by drilling.

  Further, the engine 3 according to the present embodiment has the crankshaft oil passage 73 and the piston oil passage by optimizing the flow rate of the lubricating oil branched from the main lubricant passage 69 to the cylinder side oil passage 71 and the transmission side oil passage 72. It becomes easy to ensure the flow rate of the lubricating oil branched to 75.

  Furthermore, the engine 3 according to the present embodiment optimizes the flow rate of the lubricating oil that branches from the main lubricating oil passage 69 to the cylinder-side oil supply passage 71 and the transmission-side oil supply passage 72, and the crankshaft oil supply passage 73 and the piston oil supply passage. By facilitating the securing of the flow rate of the lubricating oil branching to 75, the total flow rate of the lubricating oil can be optimized, and a smaller and less expensive oil pump 68 can be selected.

  In addition, the engine 3 according to the present embodiment has a throttle mechanism 76 disposed in a linear oil passage 83 that extends linearly in a direction orthogonal to the coupling surface 47 of the crankcase 41, so Without requiring such separate parts, the partition wall 91 of the drawing mechanism 76 can be formed by casting, which can contribute to the reduction of the number of parts and the processing cost at the same time.

  Further, the engine 3 according to the present embodiment is provided with a main lubricating oil passage 69 in the coupling surface 62 between the right crankcase half 51 and the right crankcase cover 52, and the left crankcase half 48 and the right crankcase half 51. By providing the transmission side oil supply passage 72 on the coupling surface 47, the main lubricating oil passage 69 and the transmission side oil supply passage 72 can be formed by casting. Moreover, the main lubricating oil passage 69 and the transmission side oil supply passage 72 can be collected in either one of the crankcase halves 48 and 51.

  By the way, in the case of the engine 3 according to the present embodiment, the cylinder block 42 is coupled to the crankcase 41 across the pair of left and right crankcase halves 48 and 51. Then, the coupling surface 92 between the cylinder block 42 and the crankcase 41 may be deformed unevenly between the crankcase halves 48 and 51 due to an imbalance in the tightening force of the bolts 56. In addition, if a hollow portion such as the straight oil passage 83 is formed in the vicinity of the coupling surface 92, the rigidity of the portion may be reduced, and as a result, the deformation non-uniformity may be increased. Therefore, the engine 3 according to this embodiment can suppress the reduction in rigidity around the coupling surface 92 and alleviate the unevenness of deformation by disposing the throttle mechanism 76 closer to the coupling surface 47 than the bolt hole 86. . As a result, the engine 3 according to the present embodiment can alleviate uneven deformation around the coupling surface 92 and prevent leakage of lubricating oil in the cylinder-side oil supply passage 71 across the coupling surface 92. This effect is exhibited more remarkably by overlapping the throttle mechanism 76 on the coupling surface 47 between the cylinder block 42 and the crankcase 41 when viewed in the direction of the center line of the cylinder bore 55.

  In addition, the engine 3 according to the present embodiment can integrate the throttle mechanism 76 while suppressing the rigidity of the crankcase 41 by connecting the throttle mechanism 76 to the boss having the bolt hole 86.

  Therefore, according to the engine 3 according to the present embodiment, the throttle mechanism 76 that adjusts the flow rate of the lubricating oil integrally with the crankcase 41 can be formed without requiring individual members.

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 3 Engine 5 Steering mechanism 6 Front wheel 7 Rear wheel suspension device 9 Rear wheel 11 Head pipe 15 Down tube 21 Fuel tank 23 Swing arm 27 Seat 28 Rear fender 29 Exhaust muffler 31 Front fork 32 Front fender 33 Handle 35 Rear Cushion unit 39 Frame cover 41 Crankcase 42 Cylinder block 43 Cylinder head 45 Head cover 46 Crankshaft 47 Joint surface 48 Left crankcase half 49 Left crankcase cover 51 Right crankcase half 52 Right crankcase cover 53 Piston 55 Cylinder bore 56 Bolt 57 Crank chamber 58 Transmission chamber 59 Transmission 61 Clutch chamber 62 Coupling surface 63 Magneto chamber 65 Valve chamber 66 Valve Mechanism 67 Lubrication structure 68 Oil pump 69 Main lubricating oil passage 71 Cylinder side oil supply passage 72 Transmission side oil supply passage 73 Crankshaft oil supply passage 75 Piston oil supply passage 76 Throttle mechanism 77 Intake side camshaft 78 Exhaust side camshaft 79 In-shaft oil supply passage 81 Piston jet 82 Discharge port 83 Straight oil passage 85 Orifice hole 86 Bolt hole 87 Boss 88 Upstream large diameter portion 89 Downstream large diameter portion 91 Partition 92 Binding surface 93 Cam chain tunnel

Claims (6)

A crankcase having a crank chamber and a transmission chamber;
A crankshaft housed in the crank chamber;
A transmission housed in the transmission chamber;
A cylinder block coupled to the crankcase;
A cylinder head joined to the cylinder block;
A valve operating mechanism housed in the cylinder head;
An oil pump that is provided in the crankcase and discharges lubricating oil;
A main lubricating oil passage fluidly connected to the discharge side of the oil pump;
A first oil supply passage branched from the main lubricant passage and guiding the lubricant to the cylinder head to lubricate the valve mechanism;
A second oil supply passage branched from the main lubricant passage and guiding the lubricant to the transmission chamber to lubricate the transmission;
A third oil supply passage branched from the main lubricant passage and guiding the lubricant to the crank chamber to lubricate the crankshaft;
An oil passage portion formed in the crankcase and having an upstream side connected to the main lubricant passage and branching the first oil passage and the second oil passage on the downstream side;
A throttle mechanism that collectively provides a flow rate of the lubricating oil that is provided in the oil passage and branches from the main lubricating oil passage to the first oil supply passage and the second oil supply passage ;
The throttle mechanism has a partition wall formed integrally with the crankcase, and an orifice hole that is formed in the partition wall and defines a flow rate of lubricating oil flowing from the upstream side to the downstream side of the oil passage portion. Internal combustion engine. The crankcase includes a pair of left and right crankcase halves combined at a coupling surface substantially orthogonal to the rotation center line of the crankshaft,
The diaphragm mechanism according to claim 1 provided in the oil passage portion for branching the first oil supply passage and the second oil supply passage from the main lubricating oil passage extends linearly in a direction perpendicular to the binding surface Internal combustion engine. The crankcase includes a crankcase cover that closes one of the pair of left and right crankcase halves at a second coupling surface substantially parallel to the coupling surface;
The main lubricating oil passage is provided in the second coupling surface;
The internal combustion engine according to claim 2, wherein the second oil supply passage is provided on the coupling surface of one of the left and right pair of crankcase halves. A bolt for fastening the cylinder block to the crankcase;
4. The internal combustion engine according to claim 2 , wherein the throttle mechanism is closer to the coupling surface than a bolt hole for tightening the bolt. 5. 5. The internal combustion engine according to claim 1, wherein the throttle mechanism overlaps a coupling surface between the cylinder block and the crankcase when viewed in a cylinder bore center line direction of the cylinder block. The internal combustion engine according to claim 4, wherein the throttle mechanism is connected to a boss having the bolt hole.

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