JP6197370B2 - Motorcycle engine - Google Patents

Description

  The present invention relates to an engine in which a center of a cylinder is offset from a center of a crankshaft in a vehicle such as a motorcycle.

  In a so-called offset crank engine in a motorcycle engine, by specifying the arrangement of each shaft (balancer shaft, counter shaft, drive shaft, starter motor shaft, etc.) disposed around the crankcase, the engine becomes compact and the vehicle Are being made smaller and lighter.

  For example, Patent Document 1 or Patent Document 2 discloses a publicly known public relation regarding shaft arrangement in this type of offset crank engine. In Patent Document 1, the balancer shaft is disposed on the opposite side offset from the center of the crankshaft. Further, in Patent Document 2, only the balancer shaft is offset, and the starter motor is disposed on the offset opposite side.

Japanese Patent No. 4551412 Japanese Patent No. 4451234

  In the conventional example as described above, since the cell motor and the balancer are disposed in the space at the rear of the cylinder, the position of the counter shaft in the transmission is restricted, that is, it cannot be disposed upward. For this reason, the clutch arranged on the countershaft shaft is close to the oil level of the lubricating oil, and the mechanical loss (mechanical loss) due to the resistance by the lubricating oil tends to increase. In order to avoid such a problem, there is a method in which the cylinder tilt angle is tilted forward. However, with such a cylinder arrangement, the overall length of the engine becomes long, which hinders the reduction in size and weight of the vehicle.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motorcycle engine that can effectively reduce the size and weight while simplifying the configuration.

The motorcycle engine of the present invention includes a crankshaft provided with a crank web, a cylinder whose axis is offset to one side with respect to the center of the crankshaft, a balancer weight, and the crankshaft. A balancer shaft and a starter motor shaft arranged in parallel to each other, wherein the balancer shaft and the starter motor shaft have a cylinder axis offset with respect to the crankshaft center. The starter motor shaft is arranged near the lower end of the cylinder on the cylinder side of the balancer shaft , and the tightening direction of the left and right crankcase is the same as the tightening direction of the starter motor in the crankcase Set, and the tightening screw portion of the crankcase projects integrally with the crankcase. And ends at the inner side than the engine center-side end face of the starter motor mounting arms have, characterized in that it is a step to the magneto cover mating surface.

  Further, in the motorcycle engine of the present invention, a rotation locus of the balancer weight of the balancer shaft and a rotation locus of the crank web of the crankshaft overlap with each other when viewed from the crankshaft direction, and the balancer weight of the balancer shaft The rotation trajectory is overlapped with the downward extension line parallel to the cylinder axis from the outer peripheral surface of the cylinder sleeve on the side where the cylinder axis is offset with respect to the crankshaft center in the crankshaft direction view. Features.

  The motorcycle engine of the present invention is characterized in that an engine suspension is disposed between the balancer shaft and the starter motor shaft.

  In the motorcycle engine of the present invention, a frame is disposed in front of the engine, and the balancer shaft and the starter motor shaft are disposed between the frame and the cylinder axis. .

  In the motorcycle engine of the present invention, the counter shaft and the drive shaft arranged in parallel to the crank shaft are arranged on the opposite side of the balancer shaft and the starter motor shaft with respect to the cylinder axis. It is characterized by.

  Further, in the motorcycle engine according to the present invention, the counter shaft is disposed on substantially the same plane as a plane orthogonal to the cylinder axis intersecting the balancer axis center when viewed in the crankshaft direction. To do.

  In the present invention, the balancer shaft and the starter motor are disposed on one side where the cylinder shaft center is offset with respect to the crankshaft center, and the counter shaft and the drive shaft are disposed on the other side, and between the balancer shaft and the starter motor shaft. An engine suspension with a frame arranged in the front is provided. In particular, the starter motor can be brought closer to the crankshaft, so that the number of parts can be reduced and the weight can be reduced.

1 is a side view showing an overall configuration of a motorcycle according to the present invention. Fig. 2 is a side view showing a state in which a periphery of the motorcycle according to the present invention is removed. FIG. 3 is a right side view showing the periphery of the engine mounted on the vehicle body frame in the motorcycle according to the present invention. FIG. 3 is a left side view showing the periphery of the engine mounted on the vehicle body frame in the motorcycle according to the present invention. 1 is a perspective view showing an embodiment of a motorcycle engine of the present invention. 1 is a right side view showing a state where a clutch cover is removed in an embodiment of a motorcycle engine of the present invention. 1 is a cross-sectional view showing an internal structure in an embodiment of a motorcycle engine of the present invention. 1 is a left side view and a partially enlarged view showing a state where a magnet cover is removed in an embodiment of a motorcycle engine of the present invention. FIG. 3 is a partial perspective view showing the periphery of the starter motor mounting portion in the embodiment of the motorcycle engine of the present invention. FIG. 2 is a partial right side view and a partial left side view showing the periphery of a starter motor mounting portion in an embodiment of a motorcycle engine of the present invention.

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

  The motorcycle 100 is configured by forming a vehicle body skeleton by a vehicle body frame made of steel or aluminum alloy and mounting various parts on the vehicle body frame. Although a specific configuration of the vehicle body frame will be described later, a main frame extends obliquely downward and rearward from the steering head pipe 101 coupled to the front upper end portion thereof, and a seat rail and the like are coupled in the vicinity of the rear portion of the main frame. . The power unit including the engine 10 is supported by the vehicle body frame at a substantially central portion of the vehicle body.

  The steering head pipe 101 rotatably supports a front fork 102, and a handle bar 103 is coupled to the upper end side of the front fork 102. A front wheel 104 is rotatably supported on the lower end side of the front fork 102. The upper part of the front wheel 104 is covered with a front fender 105. A swing arm 106 that can swing in the vertical direction via a pivot shaft is supported by the vehicle body frame behind the engine 10, and a rear wheel 107 is rotatably supported at the rear end portion of the swing arm 106. A shock absorber 108 is mounted between an appropriate position in the front-rear direction intermediate portion of the swing arm 106 and the vehicle body frame side. The rear wheel 107 is covered with a rear fender 109, and a seat 110 on which a rider sits is disposed above the rear wheel 107. . A fuel tank 111 is mounted on the front side of the seat 110.

  In this example, the engine 10 is an air-cooled four-cycle single-cylinder (two or more cylinders) engine. Although a detailed description of the basic configuration of the engine 10 is omitted here, a crankcase 11 that rotatably supports and accommodates a crankshaft horizontally disposed in the left-right direction, and an upper axis of the crankcase 11 are coupled to the crankcase 11. Is configured to include a cylinder 12 that is tilted forward moderately and set in a substantially vertical direction, a cylinder head 13 that is coupled to the upper portion of the cylinder 12, and a cylinder head cover 14 that covers the cylinder head 13.

  Referring also to FIG. 2, in the intake system of the power unit, a throttle body 112 is disposed between the engine 10 and an air cleaner (not shown), and an air-fuel mixture having a predetermined mixture ratio is supplied from the throttle body 112 to the intake port of the engine 10. Is done. Further, the combustion gas that has exploded and burned in the cylinder 12 of the engine 10 is discharged from the engine 10 in the exhaust system. That is, the combustion gas generated in the engine 10 passes through the exhaust pipe 113 (exhaust pipe) connected to the exhaust port of the engine 10 as exhaust gas, and is finally exhausted from the muffler 114 (exhaust silencer).

  As for the appearance of the vehicle, as shown in FIG. 1, various body covers such as a shroud 115 disposed near the upper outside of the cylinder head 13 and the cylinder head cover 14 and the side cover 116 and the rear cover 117 are supported at appropriate positions such as a body frame. To be attached. A headlamp 118 is mounted above the front wheel 104, and blinkers 119, 120, etc. are mounted before and after the vehicle.

  Further, the area around the vehicle body frame will be described with reference to FIGS. A main frame 121 extends obliquely downward and rearward from the steering head pipe 101. The main frame 121 curves downward at a substantially center in the front-rear direction of the vehicle. The pair of left and right side frames 122 in the vicinity of the lower end of the main frame 121 have a substantially portal shape. So that they are connected to the left and right. A plurality of brackets for engine mounting project from the main frame 121 and the side frame 122 to support the engine 10. A down tube 123 extends downward from the steering head pipe 101 and supports the front portion of the engine 10 (crankcase 11) via a bracket for engine mounting.

A pair of left and right seat rails 124 are coupled to the vicinity of the rear portion of the main frame 121, and the seat rails 124 extend to above the rear wheels 107. Further, a pair of left and right pillars 125 are coupled to the vicinity of the shoulder portion of the side frame 122, and these pillars 125 are coupled to the vicinity of the rear end of the seat rail 124. A body frame having a three-dimensional structure is constituted by these frame members, and high support rigidity for the engine 10 is ensured.
Further, as described above, the rear wheel 107 is supported by the swing arm 106, and the swing arm 106 can swing up and down via the pivot shaft 126. A rear cushion unit as a shock absorber 108 is mounted between the swing arm 106 and the vehicle body frame.

  The engine 10 will be further described. In the engine 10, as shown in FIG. 5, the axis 12A of the cylinder 12 coupled to the upper part of the crankcase 11 tilts appropriately forward, and a crankshaft, which will be described later, horizontally disposed in the left-right direction is rotatable in the crankcase 11. Supported. In general, this type of shaft member is referred to as a crankshaft or the like, but in the following description, the crankshaft and other shaft members are also referred to as shafts, and their shaft centers extend substantially linearly. And In this example, the crankcase 11 is divided into two by left and right cases 11L and 11R, and a clutch chamber or the like formed on the right outer side thereof is covered with a clutch cover 15. The magneto chamber formed on the left outer side of the crankcase 11 is covered with a magneto cover 16. A transmission chamber that houses the transmission device is formed on the rear side of the crankcase 11.

  6 and 7, the engine 10 has a crankshaft 17 provided with a crank web 18 and an axis 12A offset to one side (in this example, forward) with respect to the crankshaft center 17A. The (offset amount t) cylinder 12, the balancer weight 20, the balancer shaft 19 disposed in parallel to the crankshaft 17, and the starter motor shaft 21 as the rotation shaft of the starter motor 22 are disposed. .

  6 and 7, a counter shaft 23 is arranged in parallel at a predetermined interval as shown in FIGS. 6 and 7, and although not shown, a primary driven gear arranged around the counter shaft 23, It meshes with a primary drive gear arranged around the shaft 17. A clutch device is attached to the shaft end of the counter shaft 23, and power transmission between the crank shaft 17 and the counter shaft 23 is connected and disconnected via the clutch device. Further, a drive shaft 24 is arranged in parallel behind the counter shaft 23 at a predetermined interval. Each of the counter shaft 23 and the drive shaft 24 is provided with a gear train for shifting, and a transmission device that changes the gear ratio by appropriately setting the meshing relationship between the gears included in these gear trains. Composed. A sprocket is attached to the shaft end of the drive shaft 24, and the output of the drive shaft 24 is transmitted through a chain wound between the sprocket and a sprocket attached to the axle of the rear wheel 107 (FIG. 1). 107.

  As shown in FIGS. 5 to 7 and the like, the front and rear portions of the crankcase 12 are provided with a plurality of engine mount portions 25 (four locations in the example of FIG. 6) for mounting the engine 10 on the vehicle body frame. . These engine mounts 25 are coupled to the vehicle body frame (main frame 121, side frame 122, and down tube 123) directly or via a bracket, whereby the engine 10 is rigidly mounted at a predetermined position of the vehicle body frame. The cylinder head 13 is also provided with an engine mount.

  Next, main features of the engine 10 of the present invention will be described. First, the balancer shaft 19 and the starter motor shaft 21 are arranged on the side where the axis 12A of the cylinder 12 is offset with respect to the crankshaft center 17A as shown in FIG. The starter motor shaft 21 is disposed near the lower end of the cylinder 12 on the cylinder 12 side of the balancer shaft 19, that is, above the balancer shaft 19.

  Here, a starter idle shaft 26 is arranged between the starter motor shaft 21 and the crankshaft 17 in parallel with them, as shown in FIGS. The starter motor shaft 21 and the crankshaft 17 are connected to each other through a starter idle gear 27 attached around the starter idle shaft center 26A of the starter idle shaft 26. That is, first, the starter motor is arranged on the side where the axis 12A of the cylinder 12 is offset with respect to the crankshaft center 17A, as opposed to the structure in which the starter motor is arranged on the opposite side where the cylinder is offset as in the prior art. The starter motor 22 can be brought closer to the crankshaft 17. As a result, the starter idle gear 27 can be arranged with only one of the starter idle shafts 26, so that the number of parts can be reduced and the size and weight can be reduced.

  Further, as shown in FIG. 7, the rotation locus 20 </ b> A of the balancer weight 20 of the balancer shaft 19 and the rotation locus 18 </ b> A of the crank web 18 of the crankshaft 17 overlap in the crankshaft direction view (left-right direction). Further, the rotation locus 20A of the balancer weight 20 of the balancer shaft 19 is parallel to the axis 12A of the cylinder 12 from the outer peripheral surface 28a of the cylinder sleeve 28 on the side where the axis 12A of the cylinder 12 is offset from the crankshaft center 17A. It overlaps with the downward extension line 28A in the crankshaft direction view. The extension line 28 </ b> A extends downward from the foremost bus on the outer peripheral surface 28 a (cylindrical side surface) of the cylinder sleeve 28.

  By arranging the balancer weight 20 in this way, the balancer shaft 19 can be arranged closer to the crankshaft 17, and in particular, a reduction in size and weight around the crankcase 11 can be achieved. As shown in FIG. 6, the balancer shaft 19 and the crankshaft 17 are connected via a balancer idle gear 29. Such downsizing makes it easy to secure the space for the frame line of the vehicle body frame and the space for the engine suspension. Since the balancer shaft 19 is arranged on the front side of the crankcase 11, it is easy to secure the arrangement space for the down tube 123 and the engine mount 25, and the degree of freedom in designing them can be expanded. Further, as can be seen from FIG. 7 and the like, since the balancer shaft 19 is disposed below the crankshaft 17, the engine 10 and thus the motorcycle 100 as a whole can have a low center of gravity, which contributes to running stability.

Further, as shown in FIG. 6, FIG. 7, etc., an engine mount 25 is disposed between the balancer shaft 19 and the starter motor shaft 21. That is, in particular, the front engine mount 25 </ b> A is disposed substantially between the balancer shaft 19 and the starter motor shaft 21.
In this case, a down tube 123, which is a frame, is disposed in front of the engine 10 as shown in FIG. 2, and the balancer shaft 19 and starter motor shaft 21 are located between the down tube 123 and the cylinder axis 12A as can be seen from FIG. Is arranged.

  With this configuration, the distance between the down tube 123 and the pivot shaft 126 (see FIG. 3 and the like) is reduced by bringing the down tube 123 in front of the engine 10 closer to the engine 10. As a result, the front wheel 104 can be brought closer to the pivot shaft 126. As a result, the wheel base of the vehicle can be shortened, which also contributes to the reduction in size and weight.

Further, as shown in FIG. 7 and the like, the counter shaft 23 and the drive shaft 24 arranged in parallel with the crankshaft 17 are on the opposite side of the cylinder axis 12A from the arrangement side of the balancer shaft 19 and the starter motor shaft 21. Be placed.
In this case, when viewed from the side, that is, when viewed in the crankshaft direction, the counter shaft 23 is disposed on substantially the same plane as the surface 19B intersecting the balancer shaft center 19A of the balancer shaft 19 and orthogonal to the cylinder axis 12A as shown in FIG. ing.

  With this configuration, the counter shaft 23 can be arranged at a high position in the crank chamber without being affected by the starter motor shaft 21 and the balancer shaft 19. The clutch device is coaxially attached to the shaft end of the counter shaft 23. However, by increasing the height position of the counter shaft 23, the clutch does not soak deeply into the oil surface of the lubricating oil. Reduce.

  Here, the crank case 11 (see FIG. 5) including the left and right cases 11L and 11R is tightened as a tightening direction from the right case 11R side. In particular, as shown in FIG. 9, in the crankcase tightening portion 30 set at the lower end of the cylinder 12 on the cylinder 12 side of the starter motor shaft 21, the boss portion 32 through which the tightening bolt 31 is inserted into the right case 11R. The left case 11L has a screw portion 33 into which the fastening bolt 31 is screwed. The starter motor 22 is mounted on the front upper portion of the crankcase 11 as shown in FIG. 5 or FIG. 6, but as shown in FIG. 9, the starter motor 22 is integrally formed with the left case 11L and protrudes forward. The arm 34 for attachment is inserted and fixed from the right side as indicated by an arrow A in FIG.

In the above case, in FIG. 9, the screw portion 33 ends on the inner side of the end surface on the engine center (cylinder axis 12 </ b> A) side of the starter motor mounting arm portion 34, so It is a step.
Further, as shown in FIGS. 10A and 10B, the upper end of the crankcase 11 has a cylinder base surface 36 that is a mating surface for coupling with the cylinder 12. The outer peripheral surface such as the boss portion 32 of the crankcase tightening portion 30 formed in the crankcase 11 is processed below the cylinder base surface 36 (FIGS. 10A and 10B, the direction of arrow C), that is, Does not protrude upward.

  As a result, the starter motor 22 can be mounted closer to the cylinder 12, so that the longitudinal length of the engine 10 can be particularly shortened, and the wheel base of the vehicle can be shortened accordingly. In particular, in the case of an offset cylinder in which the cylinder 12 is offset forward as in this example, the front-rear length tends to be long as it is, but the effect of bringing the starter motor 22 toward the cylinder 12 is extremely great.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
Although the example in which the crankcase 11 in the above embodiment is divided into two parts by the left and right cases 11L and 11R has been described, the present invention can be similarly applied to an integral crankcase.
Moreover, although this embodiment was demonstrated with the example of the motorcycle, even if it applies with respect to another vehicle, the effect similar to the said embodiment can be acquired.

10 Engine, 11 Crankcase, 11L, 11R Case, 12 Cylinder, 13 Cylinder head, 14 Cylinder head cover, 15 Clutch cover, 16 Magnet cover, 17 Crankshaft, 18 Crank web, 19 Balancer shaft, 20 Balancer weight, 21 Starter motor Shaft, 22 starter motor, 23 counter shaft, 24 drive shaft, 25 engine mount, 26 starter idle shaft, 27 starter idle gear, 28 cylinder sleeve, 29 balancer idle gear, 30 crankcase tightening portion, 31 tightening bolt, 32 boss part, 33 screw part, 34 starter motor mounting arm part, 35 mating surface, 36 cylinder base surface, 100 motorcycle.

Claims (6)

A crankshaft provided with a crank web, a cylinder whose axis is offset on one side with respect to the center of the crankshaft, a balancer shaft provided with a balancer weight and disposed parallel to the crankshaft, and a starter motor A motorcycle engine having a shaft disposed thereon,
The balancer shaft and the starter motor shaft are arranged on the side where the cylinder axis is offset with respect to the crankshaft center,
The starter motor shaft is disposed near the lower end of the cylinder on the cylinder side of the balancer shaft ,
The tightening direction of the left and right crankcase is set to the tightening direction of the starter motor in the crankcase,
The tightening screw portion of the crankcase ends on the inner side of the engine center side end surface of the starter motor mounting arm protruding integrally with the crankcase, and is a step with the magnet cover mating surface. Motorcycle engine. A rotation locus of the balancer weight of the balancer shaft and a rotation locus of the crank web of the crankshaft overlap in the crankshaft direction view,
A rotation locus of the balancer weight of the balancer shaft includes a downward extension line parallel to the cylinder axis from the outer peripheral surface of the cylinder sleeve on the side where the cylinder axis is offset with respect to the crankshaft center, and the crankshaft. The motorcycle engine according to claim 1, wherein the motorcycle engine overlaps in a direction view.   The engine for a motorcycle according to claim 1 or 2, wherein an engine suspension is disposed between the balancer shaft and the starter motor shaft.   The frame is disposed in front of the engine, and the balancer shaft and the starter motor shaft are disposed between the frame and the cylinder axis. The motorcycle engine described.   The counter shaft and the drive shaft that are arranged in parallel to the crankshaft are arranged on the opposite side of the balancer shaft and the starter motor shaft with respect to the cylinder axis. The motorcycle engine according to claim 1.   The engine for a motorcycle according to claim 5, wherein the counter shaft is disposed on substantially the same plane as a plane that intersects with a balancer shaft center and is orthogonal to the cylinder axis when viewed in the crankshaft direction. .

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