JP6291949B2 - engine - Google Patents

Description

  The present invention relates to a dry sump engine suitable for use in a straddle-type vehicle or the like.

  Conventionally, a dry sump type engine in which engine oil collected in each crank chamber is forcibly discharged from the crank chamber by using a scavenging pump is known as an engine used in a motorcycle such as a saddle-ride type vehicle. Yes. In Patent Document 1, the crank chamber is axially divided into three independent crank chambers that are separated from each other in a substantially sealed state by two intermediate support walls that rotatably support the two intermediate journal portions of the crankshaft. A multi-cylinder four-cycle internal combustion engine in which a scavenging pump for sucking lubricating oil and blow-by gas in each independent crank chamber is provided for each independent crank chamber is disclosed. According to the multi-cylinder four-cycle internal combustion engine of Patent Document 1, the sealed crank chamber is divided into a plurality of independent crank chambers by the intermediate support wall. The flow range of the lubricating oil is limited to a narrow range, and gas inflow and outflow between adjacent independent crank chambers can be almost eliminated.

JP 2002-276317 A

  However, the multi-cylinder four-cycle internal combustion engine disclosed in Patent Document 1 has a problem that since the scavenging pump is provided for each independent crank chamber, the engine is increased in size and cannot be reduced in weight. In particular, when a multi-cylinder four-cycle internal combustion engine is used in a straddle-type vehicle such as a motorcycle, if the engine is enlarged, the tiltable angle of the vehicle body is reduced, and the turning performance may be reduced.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the size and weight of an engine that sucks engine oil in each crank chamber with a scavenging pump.

An engine of the present invention is an engine including a crankcase that houses a crankshaft, and a scavenging pump that sucks engine oil collected in a crank chamber of the crankcase through an oil suction passage. The case is formed with a plurality of crank chambers partitioned by a crankshaft support, and the oil suction passage is formed to extend from an opening formed at the bottom of each crank chamber, and at least some of the The oil suction passage is joined by a joining portion, connected to one scavenging pump, and further, the oil suction passage has a throttle portion in which a passage cross-sectional area gradually decreases from the opening to the joining portion. It is characterized by having .

  According to the present invention, the number of scavenging pumps can be reduced, and the engine can be reduced in size and weight.

1 is a left side view of a motorcycle having an engine according to an embodiment. It is a side view showing the whole engine composition. It is sectional drawing which cut | disconnected a part of crankcase. It is the figure which looked at the lower case of a crankcase from the direction orthogonal to a split surface. It is the perspective view which looked at the structure around the counter shaft and the drive shaft from the front side. It is sectional drawing which cut | disconnected a part of crankcase. It is the enlarged view to which a part of crankcase was expanded. It is sectional drawing which cut | disconnected a part of crankcase. It is the perspective view which cut | disconnected a part of crankcase. It is the figure which looked at the crankcase which removed the oil pan from the lower side.

Hereinafter, preferred embodiments of the engine of the present invention will be described with reference to the drawings.
FIG. 1 is a left side view of a motorcycle having an engine according to the present embodiment. First, the overall configuration of the motorcycle 100 will be described with reference to FIG. In the following description including FIG. 1, the front side of the vehicle is indicated by arrow Fr, the rear side of the vehicle is indicated by arrow Rr, and the right side of the vehicle is indicated by arrow R as necessary. The left side is indicated by an arrow L.

  In FIG. 1, two front forks 103 are provided at the front of a body frame 101 (main frame) made of steel or aluminum alloy so as to be turnable left and right by a steering head pipe 102. A handle bar 104 is fixed to the upper end of the front fork 103, and grips 105 are provided at both ends of the handle bar 104. A front wheel 106 is rotatably supported at the lower portion of the front fork 103, and a front fender 107 is fixed so as to cover the upper portion of the front wheel 106. The front wheel 106 has a brake disc 108 that rotates integrally with the front wheel 106.

  The vehicle body frame 101 is integrally coupled to the rear portion of the steering head pipe 102, branches into a bifurcated pair of left and right sides toward the rear side, and extends from the steering head pipe 102 while being widened rearward and obliquely downward. Here, the body frame 101 is a so-called twin spar frame that is applied to a vehicle that requires high-speed performance. Note that the seat rail 101A extends from the vicinity of the rear portion of the vehicle body frame 101 to the rear oblique upper side and extends rearward to support a seat 118 described later. A swing arm 109 is swingably coupled to the rear portion of the body frame 101, and a rear shock absorber is mounted between the body frame 101 and the swing arm 109. A rear wheel (drive wheel) 111 is rotatably supported at the rear end of the swing arm 109. The rear wheel 111 is rotationally driven via a driven sprocket 113 around which a chain 112 that transmits power of the engine 10 described later is wound. An inner fender 114 that covers the vicinity of the front upper portion is provided in the immediate vicinity of the rear wheel 111, and a rear fender 115 is disposed above the inner fender 114.

  The engine 10 mounted on the vehicle body frame 101 is supplied with air-fuel mixture including air and fuel supplied from an air cleaner and a fuel supply device (not shown), and exhaust gas after combustion in the engine 10 is exhaust pipe. And exhausted from the muffler. A fuel tank is mounted on the upper side of the engine 10, and the fuel tank is covered with a tank cover 117. A seat 118 is connected to the rear side of the fuel tank.

  In the vehicle exterior, the front and side portions of the vehicle are mainly covered by the fairing 120 and the side cowl 121, and a side cover or a seat cowl 122 is attached to the rear of the vehicle, and these exterior members have a so-called streamline type. The appearance form of the vehicle is formed.

Next, the configuration of the engine 10 as an internal combustion engine will be described.
FIG. 2 is a side view showing the overall configuration of the engine 10 in the present embodiment. The engine 10 of this embodiment uses a parallel multi-cylinder engine, specifically, a 4-cycle parallel 4-cylinder engine. The engine 10 is integrally coupled to the vehicle body frame 101 via a plurality of engine mounts, and acts as a rigid member of the vehicle body frame 101 by itself.
The engine 10 includes a crankcase 11 that accommodates and rotatably supports a crankshaft 12, a cylinder 13 that accommodates a piston in a vertically movable manner, a cylinder head 14 that accommodates a valve operating device, and a lid attached to the cylinder head 14. The cylinder head cover 15 is connected to the cylinder head cover 15. The engine 10 according to the embodiment is inclined so that the cylinder axis of the cylinder 13 is directed obliquely upward from the crankshaft 12. Further, in the engine 10 of the present embodiment, the valve gear housed in the cylinder head 14 is driven from the crankshaft 12 via a gear train (not shown).

In the engine 10 of the present embodiment, the crankcase 11 includes, in addition to the crankshaft 12, an idle shaft 16 positioned on the diagonally rear side of the crankshaft 12, a counter shaft 17 positioned on the rear side of the idle shaft 16, and a counter shaft 17 A drive shaft 18 located on the lower side is rotatably supported.
The rotation of the crankshaft 12 is transmitted in the order of the idle shaft 16, the counter shaft 17, and the drive shaft 18, and then transmitted to the chain 112 from the drive sprocket 19 that is attached to the end of the drive shaft 18. In addition, since each shaft is transmitted through a gear, the rotation direction is opposite between the upstream shaft and the downstream shaft in the power transmission direction.

  Since the engine 10 of the present embodiment has more gears than a normal engine, such as transmitting the rotation of the crankshaft 12 to the valve gear as described above, the gyro effect during running is effective. It will be bigger. Therefore, the crankshaft 12 is rotated in a direction different from the drive shaft 18 (see the arrow shown in FIG. 2) to suppress the gyro effect. Accordingly, since the rotation direction of the crankshaft 12 is opposite to the rotation direction of the normal engine, the above-described idle shaft 16 is interposed between the crankshaft 12 and the countershaft 17, so that the countershaft 17 and the drive shaft The rotational direction of 18 is returned to the rotational direction in which the vehicle moves forward.

Hereinafter, the structure around the crankcase 11 and the crankcase 11 will be described.
FIG. 3 is a cross-sectional view in which a part of the crankcase 11 is cut.
The crankcase 11 is divided into two parts, an upper case 11A and a lower case 11B, with a split surface P connecting the axis C of the crankshaft 12 and the axis of the idle shaft 16 separated. A crank chamber 20 is formed in the crankcase 11 by being partitioned by a crankshaft support portion described later.

A plurality of crank chambers 20 are formed between the upper case 11A and the lower case 11B in parallel in the vehicle width direction.
Here, a specific configuration of the crank chamber 20 will be described with reference to FIG. FIG. 4 is a view of the lower case 11B shown in FIG. 3 as viewed in the direction of the arrow perpendicular to the split surface P, that is, the II line shown in FIG.
The crankcase 11 corresponds to the first crank chamber 20a corresponding to the first cylinder, the second crank chamber 20b corresponding to the second cylinder, and the third cylinder in order from the left side along the vehicle width direction (left-right direction). A third crank chamber 20c and a fourth crank chamber 20d corresponding to the fourth cylinder are formed. The first crank chamber 20a to the fourth crank chamber 20d are configured to be independently sealed.

The first crank chamber 20a to the fourth crank chamber 20d are configured by dividing the crankshaft support portions 21 respectively formed in the upper case 11A and the lower case 11B with the split surface P. The split surface P of the crankshaft support portion 21 of the lower case 11B shown in FIG. 4 is formed with a knock pin insertion hole for alignment with the upper case 11A and a screw hole for coupling with the upper case 11A. .
The first crank chamber 20a to the fourth crank chamber 20d accommodate the crankshaft 12 rotatably supported by the crankshaft support portion 21, the side wall 22 of the first crank chamber 20a, and the side wall 22 of the fourth crank chamber 20d. Yes. As shown in FIG. 3, the crankshaft 12 is connected to a connecting rod 24 via a crankpin 23. A piston 25 is swingably attached to the tip of each connecting rod 24, and the piston 25 reciprocates up and down in the cylinder 13. Further, the inner wall surfaces of the first crank chamber 20a to the fourth crank chamber 20d are formed in a smooth cylindrical shape substantially concentric with the axis C of the crankshaft 12. Therefore, the distance between the rotating object such as the connecting rod 24 and the crank web rotated by the reciprocating motion of the piston 25 and the inner wall surface of the crank chamber 20 can be made constant, and the pumping loss between the rotating object and the inner wall surface is reduced. can do.

  As shown in FIG. 4, the crankshaft 12 has a crank web 26 and a crank drive gear 27 mounted in the first crank chamber 20a, and a pair of crank shafts in the second crank chamber 20b to the fourth crank chamber 20d. A web 26 is pivoted. The crank drive gear 27 in the first crank chamber 20 a transmits the rotation of the crankshaft 12 to the idle shaft 16. In the first crank chamber 20 a of this embodiment, the crank drive gear 27 is disposed in the crank chamber 20 by replacing one of the pair of crank webs 26 with the crank drive gear 27.

  Further, in the first crank chamber 20a to the third crank chamber 20c, the idle shaft 16 rotatably supported by the crankshaft support portion 21 is accommodated. The idle shaft 16 has a crank driven gear 28 mounted in the first crank chamber 20a, a generator drive gear 29 mounted in the second crank chamber 20b, and a balancer weight 30 mounted in the third crank chamber 20c. Has been. The crank driven gear 28 is a gear that meshes with the crank drive gear 27. The generator drive gear 29 is a gear that drives a generator disposed in the generator chamber 34 shown in FIG. The balancer weight 30 attenuates the vibration of the engine 10 caused by the rotation of the crankshaft 12.

  A primary drive gear 31 is pivotally attached to one end (right side) of the idle shaft 16. The primary drive gear 31 transmits the rotation of the idle shaft 16 to the counter shaft 17. The primary drive gear 31 is disposed outside the crank chamber 20, specifically, on the upper oblique rear side of the fourth crank chamber 20d.

Returning to FIG. 3, a mission chamber 32 is formed on the rear side of the crank chamber 20 by being separated by a case partition wall of the crankcase 11. A clutch chamber 33 is formed on the right side of the mission chamber 32, and a generator chamber 34 is formed on the upper side of the crank chamber 20.
In the mission chamber 32, a counter shaft 17 and a drive shaft 18 are rotatably supported in parallel with the crankshaft 12.

  The configuration around the counter shaft 17 and the drive shaft 18 will be described with reference to FIG. FIG. 5 is a perspective view of the configuration around the counter shaft 17 and the drive shaft 18 as seen from the front side. As shown in FIG. 5, on the right side of the countershaft 17, a primary driven gear 35 that rotates integrally with the countershaft 17 and always meshes with the above-described primary drive gear 31 is mounted. The primary driven gear 35 is disposed in the clutch chamber 33, and a clutch 36 is provided on the right side of the primary driven gear 35 (see FIG. 4). The clutch 36 is covered with a clutch cover (not shown) from the right side of the crankcase 11. The clutch 36 intermittently transmits rotation from the primary driven gear 35 to the countershaft 17 in accordance with an operation by the occupant via the clutch lever.

  The countershaft 17 is provided with a plurality of transmission gears 37. The drive shaft 18 is also provided with a plurality of transmission gears 38. In response to a shift operation by the occupant, a part of the transmission gear 37 of the countershaft 17 or a part of the transmission gear 38 of the drive shaft 18 moves in the axial direction. The combination of the transmission gears 37 and 38 that transmits the rotation from the counter shaft 17 to the drive shaft 18 is changed by the movement of the transmission gears 37 and 38 in the axial direction. Accordingly, the rotation of the crankshaft 12 passes through the idle shaft 16 and is then shifted between the counter shaft 17 and the drive shaft 18 according to the combination of the transmission gears 37 and 38 and is output to the drive sprocket 19.

Further, a shift cam 39 is rotatably supported in parallel with the crankshaft 12 below the drive shaft 18 in the mission chamber 32 (see also FIG. 3). The shift cam 39 rotates step by step by a certain angle according to the shift operation by the occupant. A plurality of cam grooves 40 are formed in the shift cam 39, and a shift fork 41 is engaged (see FIG. 3). The shift fork 41 is pivotally supported by the shift fork shaft 42 supported in parallel with the crankshaft 12 on the rear upper side of the shift cam 39 so as to be movable in the axial direction. The shift fork 41 is engaged with a part of the transmission gear 37 of the counter shaft 17 or a part of the transmission gear 38 of the drive shaft 18.
When the shift cam 39 rotates according to the shift operation by the occupant, the shift fork 41 moves along the axial direction of the shift fork shaft 42 according to the shape of the cam groove 40. Accordingly, a part of the transmission gear 37 or a part of the transmission gear 38 moves in the axial direction, and the combination of the transmission gears 37 and 38 that transmits the rotation from the counter shaft 17 to the drive shaft 18 is changed.

Further, as shown in FIG. 5, the oil pump 45, the scavenging pumps 46 (46a, 46b), and the water pump 47 are arranged on the lower side in the mission chamber 32 and obliquely below the front of the drive shaft 18 from the right side. They are arranged separately in parallel in the vehicle width direction. The oil pump 45, the scavenging pumps 46 (46a, 46b) and the water pump 47 are arranged linearly on the same axis as the drive shaft 48 which is parallel to the crankshaft 12 and rotatably supported by the crankcase 11. . The drive shaft 48 is rotated by transmitting the rotation of the primary driven gear 35 pivotally attached to the counter shaft 17 via the transmission gear portion 49. Since the countershaft 17 on which the primary driven gear 35 is attached rotates in accordance with the rotation of the crankshaft 12, the drive shaft 48 rotates in conjunction with the crankshaft 12.
Further, as shown in FIG. 5, the scavenging pump 46 (46a, 46b) is formed with a connecting portion 50 that becomes a passage through which engine oil flows toward the front side.

6 is a cross-sectional view taken along line II-II shown in FIG. As shown in FIG. 6, the drive shaft 48 is configured by connecting a plurality of shafts in the axial direction, and the oil pump 45, the scavenging pump 46, and the water pump 47 are driven by rotating. Further, as will be described later, the scavenging pump 46 of the present embodiment is configured with a smaller number (two in this case) than the number of the crank chambers 20, and an oil pump 45 and a water pump 47 are provided in the vacant spaces on both sides. Is arranged.
At this time, as shown in FIG. 6, in the engine plan view, the oil pump 45 is located on the inner side of the vehicle width from the outer end of the fourth crank chamber 20d located on the outer side of the vehicle width (see the broken line L1). Is located inside the vehicle width from the outer end of the first crank chamber 20a located outside the vehicle width (see the broken line L2). Therefore, the vehicle width direction of the crankcase 11 can be reduced, the tiltable angle of the vehicle body can be expanded, and the turning performance can be improved.

The scavenging pump 46 forcibly sucks the engine oil collected in the crank chamber 20 after lubricating the crankshaft support 21 that supports the crankshaft 12 and the piston 25 and discharges it to the mission chamber 32.
FIG. 7 is an enlarged view of FIG. 3 partially enlarged. As shown in FIG. 7, the scavenging pump 46 is disposed in the mission chamber 32, on the lower side and the rear side with respect to the axis C of the crankshaft 12 and on the lower side of the transmission gear 38. . Further, the scavenging pump 46 has a discharge hole 51 for discharging the sucked engine oil formed upward. Accordingly, the scavenging pump 46 discharges the sucked engine oil from the discharge hole 51 toward the transmission gear 38 and lubricates the transmission gear 38.

  The scavenging pump 46 of the present embodiment sucks engine oil in several crank chambers 20 with one scavenging pump 46. Specifically, the engine oil collected in the first crank chamber 20a and the second crank chamber 20b is sucked by one scavenging pump 46a and collected in the third crank chamber 20c and the fourth crank chamber 20d. The number of scavenging pumps 46 is reduced by sucking engine oil with one scavenging pump 46b.

  Here, the structure in which the scavenging pump 46 sucks the engine oil collected in the crank chamber 20 will be described with reference to FIGS. 8 is a cross-sectional view taken along the line III-III shown in FIG. 9 is a cross-sectional view taken along the line IV-IV shown in FIG.

An opening 61 is formed on the inner wall surface of the bottom 60 of each of the first crank chamber 20a to the fourth crank chamber 20d of the present embodiment. As shown in FIG. 8, the opening 61 is formed over the chamber width of each of the first crank chamber 20a to the fourth crank chamber 20d. Further, as shown in FIG. 7, the opening 61 is formed at a position overlapping with a straight line that hangs down from the axis C of the crankshaft 12. Further, an oil suction passage 63 serving as an engine oil passage is formed integrally with the lower case 11B from the opening 61 to the insertion hole 62 connected by the connection portion 50 of the scavenging pump 46 being inserted. The
Specifically, the oil suction passage 63 is inclined from the opening 61 toward the front obliquely lower side, and is folded and extended to the rear side via the substantially V-shaped bent portion 64. Up to 62 are formed. The folding angle of the bent portion 64 is set to an angle at which the insertion hole 62 and the connecting portion 50 are connected at a short distance.

  Here, the oil suction passage 63 extending from the opening 61 to the bent portion 64 extends toward the front side and extends in the tangential direction of the cylindrical shape of the crank chamber 20. In the crank chamber 20, the engine oil moves in the same direction as the rotation direction of the crankshaft 12 (the arrow direction shown in FIG. 7) by being stirred by the crank web 26. Therefore, by extending the oil suction passage 63 from the opening 61 to the bent portion 64 as described above, the engine oil can enter the oil suction passage 63 while maintaining kinetic energy. Further, by forming the bent portion 64, even when the rotation direction of the crankshaft 12 is reverse to the rotation direction of the normal engine, the scavenging pump 46 disposed on the rear side of the axis C of the crankshaft 12 is used. Can guide the engine oil up to.

  In the bent portion 64, a chamber portion 65 having a passage cross-sectional area larger than the passage cross-sectional area of the passage from the opening 61 to the bent portion 64 is formed. Therefore, the pressure loss can be reduced by forming the chamber portion 65 in the bent portion 64 where the pressure loss occurs when the engine oil is sucked by the scavenging pump 46 to increase the passage cross-sectional area, and the efficiency of the engine oil suction is increased. Can be improved.

  Further, as described above, in order to suck the engine oil in several crank chambers 20 by one scavenging pump 46, several oil suction passages 63 are formed by merging by merging portions 66 (66a, 66b). Is done. Specifically, as shown in FIGS. 8 and 9, a joining portion in which the oil suction passage 63 of the first crank chamber 20 a and the oil suction passage 63 of the adjacent second crank chamber 20 b are formed in the chamber portion 65. 66a. Here, the junction 66a is formed on the front side of the opening 61 of the second crank chamber 20b. Accordingly, the oil suction passage 63 extending from the opening 61 of the second crank chamber 20b extends straight forward from the opening 61 to the junction 66a. On the other hand, the oil suction passage 63 extending from the opening 61 of the first crank chamber 20a reaches the junction 66a via a passage along the width direction toward the center in the vehicle width direction. One oil suction passage 63 joined by the joining portion 66a extends rearward at a position overlapping the second crank chamber 20b in the plan view of the engine, and is connected to the scavenge via the insertion hole 62 and the connecting portion 50. Connected to the ring pump 46a.

  Similarly, as shown in FIGS. 8 and 9, an oil suction passage 63 of the third crank chamber 20c and an oil suction passage 63 of the adjacent fourth crank chamber 20d are formed by a joining portion 66b formed in the chamber portion 65. Merged. Here, the merging portion 66b is formed on the front side of the opening 61 of the third crank chamber 20c. Accordingly, the oil suction passage 63 extending from the opening 61 of the third crank chamber 20c extends straight forward from the opening 61 to reach the junction 66b. On the other hand, the oil suction passage 63 extending from the opening 61 of the fourth crank chamber 20d reaches the junction 66b via a passage along the width direction toward the center in the vehicle width direction. One oil suction passage 63 joined by the joining portion 66b extends rearward at a position overlapping the third crank chamber 20c in the engine plan view, and is connected to the scavenge via the insertion hole 62 and the connecting portion 50. Connected to the ring pump 46b.

  As described above, the number of the scavenging pumps 46 can be reduced by joining several oil suction passages 63 by the joining portions 66a and 66b and connecting to the scavenging pumps 46, and the engine 10 can be reduced in size and weight. Can be achieved. In this embodiment, since the oil suction passages 63 connected to the adjacent crank chambers 20 are joined together, the joining portions 66a and 66b can be formed in a simplified manner. Further, when the oil suction passage 63 is merged, the oil suction passage 63 extending from the opening 61 of the crank chamber 20 located outside in the vehicle width direction extends along the width direction toward the center portion in the vehicle width direction. Since it reaches the junctions 66a and 66b via the passage, the vehicle width direction of the crankcase 11 can be reduced, the tiltable angle of the vehicle body can be expanded, and the turning performance can be improved.

  Further, as shown in FIG. 8, each oil suction passage 63 is formed with a throttle portion 67 whose passage cross-sectional area gradually decreases from the opening 61 to the joining portions 66 a and 66 b. As in the present embodiment, by joining the oil suction passages 63 connected to the crank chamber 20, the crank chambers 20 are communicated with each other via the joining portions 66a and 66b. Therefore, even if a pressure difference occurs between the crank chambers 20 due to pumping of the piston 25, the influence of the pressure exerted by one crank chamber 20 on the other crank chamber 20 can be reduced by the throttle portion 67 that gradually decreases.

As shown in FIG. 7, an oil pan 70 is coupled to the lower end surface F of the crankcase 11 via a plurality of fixing screws 71. A part of the oil pan 70 protrudes from the right side of the exhaust pipe so as not to interfere with the exhaust pipe.
Here, in FIG. 7, the oil pan 70 and the scavenging pump 46 are removed, and the state seen from the axial direction (direction of arrow A shown in FIG. 7) of the insertion hole 62 of the oil suction passage 63 is described with reference to FIG. explain.

  As shown in FIG. 10, the insertion hole 62 of the oil suction passage 63 extending rearward from the merging portion 66a and the insertion hole 62 of the oil suction passage 63 extending rearward from the merging portion 66b Is accommodated in an opening 72 surrounded by a lower end surface F of the crankcase 11. Therefore, for example, a drill blade can be inserted from the direction of arrow A shown in FIG. 7 through the opening 72, and post-processing of the insertion hole 62 can be easily performed. That is, the angle in the axial direction of the insertion hole 62 is set to an angle that allows the shortest connection with the connection portion 50 of the scavenging pump 46 among the angles at which the post-processing of the insertion hole 62 can be performed. Yes.

  As shown in FIG. 3, an oil cooler 75 is supported via a plurality of stays at a position on the front side of the crankcase 11 and the oil pan 70 and away from the crankcase 11 and the oil pan 70. One end of the inlet hose 76 is coupled to the upper portion of the oil cooler 75, and one end of the outlet hose 77 is coupled to the lower portion. The other end of the inlet hose 76 is coupled to the front surface of the lower case 11 </ b> B of the crankcase 11 and is connected to the oil pump 45 in the crankcase 11. The other end of the outlet hose 77 is coupled to a substantially corner portion formed by the front surface and the right side surface of the lower case 11B via the lower case 11B of the crankcase 11 and the front side of the oil pan 70, and the right side of the lower case 11B. The oil filter 78 is detachably mounted on the surface.

  Therefore, the engine oil stored in the oil pan 70 is sucked by the oil pump 45 and is pumped to the oil cooler 75 via the inlet hose 76. The engine oil pumped to the oil cooler 75 is cooled and pumped from the outlet hose 77 to the oil filter 78. The engine oil pumped to the oil filter 78 is supplied to each part of the engine 10 after the foreign matters contained in the engine oil are removed and cleaned. Specifically, the engine oil is supplied to, for example, the valve operating device of the cylinder head 14, the transmission gears 37 and 38, the crankshaft support 21 and the piston 25. The engine oil that has lubricated the transmission gears 37, 38, etc. is collected in the oil pan 70 through the mission chamber 32, and the engine oil that has lubricated the crankshaft support portion 21, the piston 25, etc. is in the first crank chamber 20a to the fourth crank chamber. Recovered to 20d.

  The engine oil and blow-by gas collected in the first crank chamber 20 a to the fourth crank chamber 20 d are forcibly sucked from the openings 61 toward the oil suction passage 63 by the scavenging pump 46. At this time, since the first crank chamber 20a to the fourth crank chamber 20d are independently formed, the scavenging pump 46 can efficiently suck engine oil and blow-by gas. Therefore, the engine oil does not remain in the first crank chamber 20a to the fourth crank chamber 20d and can be sufficiently discharged.

  Engine oil that has passed through the oil intake passages 63 is merged by the merging portions 66 a and 66 b and is discharged toward the transmission gear 37 from the discharge hole 51 of the scavenging pump 46. Here, the scavenging pump 46 does not discharge engine oil directly to the engine oil stored in the oil pan 70 but discharges it toward the transmission gear 37. Therefore, since the engine oil in the oil pan 70 is not agitated, the generation of bubbles can be suppressed. The engine oil discharged from the discharge hole 51 and lubricating the transmission gear 37 is dropped and collected in the oil pan 70.

  As described above, according to the present embodiment, the number of scavenging pumps 46 can be reduced by joining several oil suction passages 63 by the joining portions 66a and 66b and connecting them to the scavenging pump 46. 10 can be reduced in size and weight. Moreover, by reducing the number of scavenging pumps 46, the vehicle width direction of the crankcase 11 can be reduced, the tiltable angle of the vehicle body can be expanded, and the turning performance can be improved.

  Further, in the present embodiment, each oil suction passage 63 is formed with a throttle portion 67 in which the passage cross-sectional area gradually decreases from the opening 61 to the joining portions 66a and 66b. Therefore, even if a pressure difference occurs between the crank chambers 20 due to pumping of the piston 25, the influence of the pressure exerted by one crank chamber 20 on the other crank chamber 20 can be reduced by the throttle portion 67 that gradually decreases.

  In the present embodiment, the bent portion 64 is formed with a chamber portion 65 whose passage cross-sectional area is larger than the passage cross-sectional area of the passage from the opening 61 to the bent portion 64. Therefore, the pressure loss can be reduced by forming the chamber portion 65 in the bent portion 64 where the pressure loss occurs when the engine oil is sucked by the scavenging pump 46 to increase the passage cross-sectional area, and the efficiency of the engine oil suction is increased. Can be improved.

  In the present embodiment, the inner wall surfaces of the first crank chamber 20a to the fourth crank chamber 20d are formed in a smooth cylindrical shape substantially concentric with the axis C of the crankshaft 12. Therefore, the distance between the rotating object such as the connecting rod 24 and the crank web 26 that is rotated by the reciprocating motion of the piston 25 and the inner wall surface of the crank chamber 20 can be made constant, and the pumping loss between the rotating object and the inner wall surface can be reduced. Can be reduced.

  In the present embodiment, the oil suction passage 63 extending from the opening 61 to the bent portion 64 extends in the cylindrical tangential direction of the crank chamber 20. Therefore, engine oil that moves in the same direction as the rotation direction of the crankshaft 12 can enter the oil intake passage 63 while maintaining kinetic energy, and the efficiency of intake of engine oil can be improved.

  Further, in the present embodiment, the opening 61 of each crank chamber 20 is formed at a position that overlaps with a straight line hanging from the axis C of the crankshaft 12. Therefore, the engine oil that adheres to the inner wall surface of the crank chamber 20 and hangs down is collected by the opening 61. In addition, since the engine oil that has dropped and adhered to the inner wall surface is swept away by the engine oil that moves in the same direction as the rotation direction of the crankshaft 12, the efficiency of intake of the engine oil can be improved.

  In the present embodiment, the scavenging pump 46 is formed with a discharge hole 51 for discharging the sucked engine oil facing upward. Therefore, since the engine oil in the oil pan 70 is not agitated, the generation of bubbles can be suppressed and the transmission gear 37 can be lubricated.

  In the present embodiment, the oil pump 45 is positioned on the vehicle width inner side than the outer side of the fourth crank chamber 20d of the crankcase 11, and the water pump 47 is positioned on the vehicle width side of the outer side of the first crank chamber 20a of the crankcase 11. Located inside. Therefore, the vehicle width direction of the crankcase 11 can be reduced, the tiltable angle of the vehicle body can be expanded, and the turning performance can be improved.

As mentioned above, although this invention was demonstrated using embodiment mentioned above, this invention is not limited only to embodiment mentioned above, A change etc. are possible within the scope of the present invention.
In the above-described embodiment, the case where the rotation direction of the crankshaft 12 is reverse to the rotation direction of the normal engine has been described. However, the present invention is not limited to this case, and even if the rotation direction is the same as the rotation direction of the normal engine. Good.
In the above-described embodiment, the case where the engine 10 is a parallel four-cylinder engine has been described.
In the above-described embodiment, the case where the engine 10 is applied to a motorcycle has been described. However, the present invention is not limited to this case, and can be applied to a vehicle having a similar structure.

  10: Engine 11: Crankcase 11A: Upper case 11B: Lower case 12: Crankshaft 13: Cylinder 14: Cylinder head 16: Idle shaft 17: Counter shaft 18: Drive shaft 20: Crank chamber 20a-20d: First crank chamber Fourth crank chamber 21: Crankshaft support 22: Side wall 31: Transmission chamber 32: Clutch chamber 45: Oil pump 46 (46a, 46b): Scavenging pump 47: Water pump 48: Drive shaft 49: Transmission gear section 51: Discharge hole 61: Opening part 63: Oil suction passage 64: Bending part 65: Chamber part 66 (66a, 66b): Junction part 67: Restriction part 100: Motorcycle

Claims (8)

An engine comprising: a crankcase that houses a crankshaft; and a scavenging pump that sucks engine oil collected in a crank chamber of the crankcase through an oil suction passage.
The crankcase is formed with a plurality of crank chambers partitioned by a crankshaft support.
The oil suction passage is formed to extend from an opening formed at the bottom of each crank chamber,
At least some of the oil suction passages are joined by a junction and connected to one of the scavenging pumps ;
Furthermore, the oil suction passage has a throttle portion in which a passage cross-sectional area gradually decreases from the opening to the junction . The oil suction passage has a bent portion from the opening to the scavenging pump, and a chamber portion having an enlarged passage cross-sectional area is formed in the bent portion. engine according to 1. The engine according to claim 1 or 2 , wherein an inner wall surface of the crank chamber has a smooth cylindrical shape substantially concentric with an axis of the crankshaft. The engine according to claim 3 , wherein the oil suction passage is formed to extend in a tangential direction of the cylindrical shape from the opening in a side view of the engine. The engine according to any one of claims 1 to 4 , wherein the opening is formed at a position overlapping a straight line depending from an axis of the crankshaft in a side view of the engine. The scavenging pump is disposed at a lower side and a rear side with respect to an axis of the crankshaft in a side view of the engine, and below a transmission gear disposed at a rear side of the crank chamber,
The engine according to any one of claims 1 to 5 , wherein a discharge hole of the scavenging pump is formed upward. The scavenging pump is arranged in parallel with a separate oil pump in the vehicle width direction, and the drive shaft is coaxial.
The engine according to any one of claims 1 to 6 , wherein the oil pump is located inside the vehicle width from the outer end of the crank chamber located outside the vehicle width in a plan view of the engine. The scavenging pump is arranged in parallel with a separate water pump in the vehicle width direction and the drive shaft is coaxial.
The engine according to any one of claims 1 to 7 , wherein the water pump is located inside the vehicle width from the outer end of the crank chamber located outside the vehicle width in a plan view of the engine.

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