JP4029890B2 - Secondary balancer support structure for motorcycles - Google Patents

Description

  The present invention relates to a secondary balancer support structure for a motorcycle.

  A four-cycle engine mounted on a vehicle is likely to generate vibration based on the reciprocating motion of a piston. Therefore, some engines include a balancer device for removing this vibration. The balancer device is, for example, a primary balancer device in which a web is integrally formed on a crankshaft, and a balancer weight corresponding to the total mass of a piston, a connecting rod, etc. is provided on the balancer shaft, and the engine is operated by rotating this weight in conjunction with the crankshaft There is a secondary balancer device that eliminates vibrations of time.

  In a conventional secondary balancer for a motorcycle, for example, a balancer shaft is press-fitted and fixed to a crankcase, and a balancer weight is rotatably supported on the outer periphery of the balancer shaft via a needle bearing. That is, the balancer weight rotates relative to the fixed balancer shaft.

  However, since the balancer weight rotates at twice the number of rotations of the crankshaft in the secondary balancer device, the roller of the needle bearing is likely to wear, and if the roller wears, the gap on the sliding contact surface will expand and play will occur. However, the malfunction that rotation behavior becomes large arises.

  Moreover, when the clearance gap of the sliding contact surface expands, the oil film breakage of the sliding contact surface occurs, and the lubrication performance of the secondary balancer device decreases.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a secondary balancer support structure for a motorcycle in which rotational behavior is reduced.

In order to solve the above-described problem, the secondary balancer support structure for a motorcycle according to the present invention is a parallel four-cylinder engine having a crankshaft and a secondary balancer device separately as described in claim 1. A power generator is provided at one end of the crankshaft, and a cam drive sprocket that is operatively connected via a cam chain to a valve gear provided in the cylinder head at the other end, and on the outermost side opposite to the power generator. A primary drive gear is integrally formed on a crank web for a cylinder disposed, and the power generator of the crankshaft is a cylinder separated from the crank web provided with the primary drive gear by one cylinder. Kurankuji between the central second cylinder of the crank web for the cylinder adjacent to the cylinder which is disposed on the mounting portion side outermost Formed integrally with the balancer drive gear crank web located on the far side from Naru section, the balancer shaft constituting the secondary balancer device driven in this balancer drive gear a front of the crankshaft the crank shaft A balancer that is disposed on the ground side and on the opposite side of the oil pan with respect to the height direction from the bearing portion to the crankcase of the crankcase, and that has a balancer weight that constitutes the secondary balancer device driven by the balancer drive gear. It is characterized by being arranged on the side closer to the crank journal portion between the central two cylinders with respect to the driven gear .

In order to solve the above-described problem, as described in claim 2, the parallel four-cylinder engine has a cylinder block that is inclined forward, and in the vehicle side view, the cylinder block is disposed below the cylinder block and the crank block. The front side of the crankcase located in front of the shaft bulges toward the front of the vehicle, and the secondary balancer device is disposed inside the crankcase .
Furthermore, in order to solve the above-described problem, as described in claim 3, the secondary balancer device is supported by a crankcase in front of a cylinder of a crank web on which the balancer drive gear is formed. .

According to the secondary balancer support structure for a motorcycle according to the present invention, the burden on the crankshaft when driving the secondary balancer device whose rotational speed is increased from the crankshaft is reduced, and the rotational behavior is reduced. be able to. In addition, the front and rear length of the engine can be shortened and the engine can be made compact, and the mass can be concentrated, thereby improving the steering stability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a left side view showing an example of a motorcycle to which the present invention is applied.

  As shown in FIG. 1, the motorcycle 1 has a body frame 2, and a head pipe 3 is provided in front of the body frame 2. The head pipe 3 is provided with a suspension mechanism (not shown) and is provided with a steering mechanism 7 including a pair of left and right front forks 5 and a handle bar 6 that rotatably supports the front wheel 4. Is steered so as to be pivotable left and right.

  On the other hand, the body frame 2 is, for example, a twin-tube type, and is expanded to the left and right immediately after the head pipe 3 and then a pair of left and right main frames 8 that also serve as tank rails extending in the rear obliquely downward direction. A pair of left and right center frames 9 connected to the rear end of the main frame 8 and extending substantially upward and downward, and a pair of left and right seat rails 10 extending rearward from the rear upper end of the center frame 9 are configured. .

  A fuel tank 11 is disposed above the main frame 8, and an operation seat 12 is disposed above the seat rail 10. Further, a pivot shaft 13 is installed at a substantially central lower portion of the center frame 9, and a swing arm 14 is pivotally attached to the pivot shaft 13 so as to be swingable around the pivot shaft 13, and at the rear end of the swing arm 14. The wheel 15 is pivotally supported. An engine 16 is attached to the main frame 8 below the center of the vehicle body and below the fuel tank 11.

  Further, in the motorcycle 1, the front portion of the vehicle body is covered with a streamlined cowling 17 so as to reduce air resistance during traveling and to protect the rider from traveling wind pressure.

  FIG. 2 is a left side view of the engine 16, most of which is shown in a longitudinal section. As shown in FIG. 2, the engine 16 is, for example, a four-cycle parallel four-cylinder engine, and has an outer shape mainly composed of a cylinder head cover 18, a cylinder head 19, a cylinder block 20, and a crankcase 21.

  The crankcase 21 is of a split type, and is composed of, for example, an upper crankcase 21a, a center crankcase 21b, and a lower crankcase 21c, which are divided into three in the vertical direction in the figure and in which the cylinder block 20 is integrally formed.

  FIG. 3 is a diagram simply illustrating the relationship between the divided state of the crankcase 21 and shafts described later. As shown in FIGS. 2 and 3, the cylinder block 20 is disposed at a slight forward inclination from the upright position, and the split surfaces of the crankcases 21a, 21b, 21c are forwardly lowered perpendicularly to the central axis 22 of the cylinder block 20 ( The lower surface of the lower crankcase 21c, which is the lower crankcase 21, is formed substantially horizontally.

  FIG. 4 is a plan view of the center crankcase 21b, and the devices arranged on the split surfaces of the upper crankcase 21a and the center crankcase 21b are shown in cross section.

  A crankshaft 23 extending in the width direction of the engine 16 is rotatably supported on a split surface between the upper crankcase 21a and the center crankcase 21b. Further, behind the crankshaft 23, a countershaft 24 and a drive shaft 25 that extend in the width direction of the engine 16 (arranged in parallel with the crankshaft 23) are rotatable on the split surfaces of the center crankcase 21b and the lower crankcase 21c. Supported by

  A power generator 26 is provided at one end of the crankshaft 23. On the other hand, a cam drive sprocket 27 is provided at the other end of the crankshaft 23. The cam drive sprocket 27 is operatively connected via a cam chain (not shown) to a cam driven sprocket (not shown) provided at the end of the camshaft 29 of a valve gear 28 provided in the cylinder head 19. Then, the rotation of the crankshaft 23 is transmitted to the camshaft 29 via the cam chain, whereby the valve operating device 28 is operated and the intake / exhaust valve 30 is opened / closed. The upper part of the cylinder head 19 is closed by the cylinder head cover 18.

  A crank web 31 as a primary balancer device is formed on the crankshaft 23 corresponding to each cylinder. A primary drive gear 33 that is operatively connected to a primary driven gear 32 formed on the countershaft 24 is formed integrally with a cylinder crank web 31 that is disposed on the opposite side of the power generation device 26. Further, a balancer drive gear 34 is integrally formed on a crank web 31 for a cylinder separated from at least one cylinder from the end of the crankshaft 23 on the power generator 26 attachment portion side.

  A large end portion 36 a of a connecting rod 35 is connected to the crankshaft 23, and a piston 37 is connected to a small end portion 36 b of the connecting rod 35. A piston 37 is accommodated in the cylinder block 20 so as to be slidable in the direction of the central axis 22 of the cylinder block 20 in FIG. A combustion chamber 38 is formed in the space between the cylinder head 19 and the piston 37, and a spark plug (not shown) is screwed to the center of the combustion chamber 38 from the outside.

  The reciprocating stroke of the piston 37 is converted into a rotational motion by the crankshaft 23 and transmitted to a clutch mechanism (not shown) provided on the countershaft 24 via both primary gears 32 and 33. A transmission mechanism 39 is provided between the countershaft 24 and the drive shaft 25, and the rotational movement of the crankshaft 23 is finally driven by the drive wheels via the drive shaft 25 and the drive chain 40 (see FIG. 1). It is transmitted to a certain rear wheel 15.

  Incidentally, the air-fuel mixture supply means to the engine 16 used in the motorcycle 1 is a fuel injection type, and a throttle body 43 having a fuel injector 42 is connected to an intake port 41 formed in the cylinder head 19. The throttle body 43 is disposed on the rear upper side of the engine 16, and an air cleaner 44 is connected to the upstream side of the throttle body 43.

  The engine 16 is provided with an engine lubrication device. Lubricating oil stored in an oil pan 45 provided in the lower portion of the lower crankcase 21c is supplied to the crankshaft 23 via an oil filter 46 by an oil pump (not shown). Or the valve operating device 28, the transmission mechanism 39, and the like.

  The engine 16 includes a secondary balancer device 47 in addition to the primary balancer device provided on the crankshaft 23. As shown in FIGS. 2 to 4, the secondary balancer device 47 is provided on a split surface between the upper crankcase 21 a and the center crankcase 21 b on which the crankshaft 23 is rotatably supported, and in front of the crankshaft 23. Placed in.

  5 is an enlarged view of the secondary balancer device mounting portion shown in FIG. 4, and FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. As shown in FIG. 5, the secondary balancer device 47 is composed of a balancer shaft 48 and a balancer weight 49 formed integrally with the balancer shaft 48. As shown in FIG. 6, the balancer shaft 48 is composed of an upper crankcase. 21a and the center crankcase 21b are rotatably supported via a metal bearing 50 on a split surface. Further, the metal bearing 50 is of a half type, and is arranged such that its crankcase split surface coincides with the split surfaces of the upper crankcase 21a and the center crankcase 21b.

  Further, a balancer driven gear 51 operatively connected to the balancer drive gear 34 is attached to the balancer shaft 48 so as to rotate integrally. A damper 52 made of an elastic body is interposed between the balancer shaft 48 and the balancer driven gear 51.

  Next, the operation of this embodiment will be described.

  The crankcase 21 is divided into three in the vertical direction, the cylinder block 20 formed integrally with the upper crankcase 21a is inclined forward, and the crankcases 21a, 21b, 21c perpendicular to the central axis 22 of the cylinder block 20 are divided. Of the surfaces, the balancer shaft 48 and the crankshaft 23 are arranged on the upper crankcase splitting surface, in this embodiment the splitting surfaces of the upper crankcase 21a and the center crankcase 21b, and the countershaft 24 and the driveshaft 25 Are arranged on the lower crankcase splitting surface, in this embodiment, the splitting surfaces of the center crankcase 21b and the lower crankcase 21c, so that the shafts 23, 24, 25, and 48 are aligned in a straight line. The front and rear length of the engine 16 has been shortened With compact becomes possible come, it is possible to mass concentration, the steering stability is improved.

  In addition, since the crankshaft 23 and the balancer shaft 48 are sources of vibrations, the crankshaft 23 and the balancer shaft 48 are arranged on a crankcase split surface different from the countershaft 24 and the drive shaft 25. If only the fastening force of the crankcase split surface on which the balancer shaft 48 is arranged, in this embodiment, the split surface of the upper crankcase 21a and the center crankcase 21b, is set higher than the fastening force of the other crankcase split surface. As it is good, the efficiency at the time of assembly improves.

  Further, the secondary balancer device 47 is composed of a balancer shaft 48 and a balancer weight 49 formed integrally with the balancer shaft 48, and the balancer shaft 48 is a metal bearing on a split surface between the upper crankcase 21a and the center crankcase 21b. Since it is rotatably supported via 50, the number of parts can be reduced and the assembling property is improved. Further, it is difficult to form a gap on the sliding contact surface between the balancer shaft 48 and the metal bearing 50, and play, that is, rotational behavior is suppressed, and oil film breakage on the sliding contact surface is less likely to occur, and the secondary balancer device 47 is lubricated. Performance is improved.

  Furthermore, the metal bearing 50 is of a half-split type, and the split surface thereof is arranged so as to coincide with the split surfaces of the upper crankcase 21a and the center crankcase 21b, so that the secondary balancer device 47 can be assembled. Will improve.

  By the way, since the power generator 26 and the primary drive gear 33, which are heavy rotating bodies, are provided at both ends of the crankshaft 23, the parts that do not place a relatively heavy burden on the crankshaft 23, in this embodiment, the power generator 26 mounting portion. By providing the balancer drive gear 34 for driving the secondary balancer device 47 on the crank web 31 for the cylinder separated at least one cylinder from the side end, the secondary speed is increased to twice the rotational speed of the crankshaft 23. The burden on the crankshaft 23 when driving the balancer device 47 is reduced.

  Further, the secondary balancer device 47 that is accelerated to twice the number of revolutions of the crankshaft 23 responds sensitively to fluctuations in the rotation of the engine 16, but a damper made of an elastic body between the balancer shaft 48 and the balancer driven gear 51. Since the damper 52 is interposed, the damper 52 can absorb the rotational fluctuation of the engine 16.

1 is a left side view of a motorcycle showing an embodiment of a secondary balancer support structure for a motorcycle according to the present invention. The left view of an engine. The figure which represents easily the division | segmentation state of a crankcase, and the relationship with shafts. The top view of a center crankcase. The enlarged view of the secondary balancer apparatus attaching part shown in FIG. Sectional drawing which follows the VI-VI line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motorcycle 16 Engine 19 Cylinder head 21a Upper crankcase 21b Center crankcase 21c Lower crankcase 23 Crankshaft 26 Electric power generating device 27 Cam drive sprocket 28 Valve operating device 31 Crank web (primary balancer device)
33 Primary drive gear 34 Balancer drive gear 47 Secondary balancer device 48 Balancer shaft

Claims (3)

In a parallel four-cylinder engine having a crankshaft and a secondary balancer device separately, a power generator is provided at one end of the crankshaft, and the other end is operatively connected to a valve gear provided in the cylinder head via a cam chain. Cam drive sprocket to be installed,
A primary drive gear is integrally formed on a crank web for a cylinder disposed on the outermost side opposite to the power generation device, and the cylinder is separated from the crank web provided with the primary drive gear by one cylinder. And a balancer drive gear on the crank web located on the far side from the crank journal portion between the center two cylinders of the crank web for the cylinder adjacent to the cylinder arranged on the outermost side of the crankshaft on the power generator mounting portion side. Integrally formed,
The balancer shaft that constitutes the secondary balancer device driven by the balancer drive gear is disposed in front of the crankshaft and sandwiches an oil filter with respect to the ground side and the height direction from the bearing portion of the crankshaft to the crankcase. Place it on the opposite side of the oil pan ,
The balancer weight of the motorcycle is characterized in that the balancer weight constituting the secondary balancer device is arranged on the side closer to the crank journal portion between the central two cylinders with respect to the balancer driven gear driven by the balancer drive gear. Construction. The cylinder block of the parallel four-cylinder engine is disposed forwardly, and in front of the vehicle, the front of the crankcase located below the cylinder block and in front of the crankshaft bulges toward the front of the vehicle. The secondary balancer support structure for a motorcycle according to claim 1, wherein the secondary balancer device is disposed on the inside thereof. The secondary balancer support structure for a motorcycle according to claim 1 or 2, wherein the secondary balancer device is supported by a crankcase in front of a cylinder of a crank web on which the balancer drive gear is formed.

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