JP2006170236A - Shift drum driving mechanism for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size of a shift drum driving mechanism for a vehicle including a lost motion mechanism in the shift drum driving mechanism for the vehicle used for cutting out or connecting a power transmission route in a drive force transmitting mechanism or switching the shift stages of a transmission. <P>SOLUTION: This shift drum driving mechanism for the vehicle comprises a shift fork, a shift drum, a shift drum shaft inserted into the shift drum, rotatably supporting the shift drum, and rotatably supported on a plurality of support parts, and the lost motion mechanism installed on the shift drum shaft and transmitting the rotation of the shift drum shaft to the shift drum through a lost motion spring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicular shift drum drive mechanism that is used to cut off or connect a power transmission path in a driving force transmission mechanism or to switch a gear position in a transmission.

  There is an example of a vehicle shift drum drive mechanism having a lost motion mechanism provided on a shift drum shaft provided separately from the shift drum outside the bearing that rotatably supports the shift drum (for example, (See Patent Document 1). In such a structure, since the lost motion mechanism protrudes from the side of the shift drum, the shift drum drive mechanism including the lost motion mechanism not only occupies a large space, but also supports the both ends of the shift drum. In addition to this, a bearing portion for supporting one end of the shift drum shaft is required, resulting in an increase in the size of the transmission, a complicated mechanism, and an increase in the number of parts.

Japanese Patent No. 3044498.

  An object of the present invention is to eliminate the drawbacks of the prior art and to reduce the size of a vehicle shift drum drive mechanism including a lost motion mechanism.

  The present invention solves the above-mentioned problems, and the invention according to claim 1 is a vehicle used to cut off or connect a power transmission path in a driving force transmission mechanism, or to switch a gear position in a transmission. A shift fork, a shift drum, and a shift drum shaft that is inserted into the shift drum and rotatably supports the shift drum and is rotatably supported by a plurality of support portions. And a lost motion mechanism that is provided on the shift drum shaft and transmits the rotation of the shift drum shaft to the shift drum via a lost motion spring. is there.

  According to a second aspect of the present invention, in the vehicle shift drum drive mechanism according to the first aspect, the lost motion mechanism is provided on an input transmission member (shift drum shaft drive wheel) provided at one end of the shift drum shaft. On the other hand, it is arranged in the vicinity of the other shift drum shaft end.

  According to a third aspect of the present invention, in the vehicle shift drum drive mechanism according to the first or second aspect, the lost motion mechanism is provided adjacent to the shift drum. .

  According to a fourth aspect of the present invention, in the vehicle shift drum drive mechanism according to the first to third aspects, the lost motion mechanism is used as a drive force transmission mechanism that is switched by a single shift fork. It is characterized by this.

  According to a fifth aspect of the present invention, in the vehicular shift drum drive mechanism according to the first to fourth aspects, the shift drum shaft side abutment is provided on the shift drum shaft so as to be integrally rotatable and abuts on the lost motion spring. And a shift drum side abutting portion that is provided on the shift drum so as to be integrally rotatable and abuts on the lost motion spring, is provided between the lost motion spring and the shift drum.

  According to a sixth aspect of the present invention, in the vehicle shift drum drive mechanism according to the first to fifth aspects, the position detector for detecting the position of the shift drum is a detector with respect to the axial direction of the shift drum. Are arranged in a direction orthogonal to each other.

  According to the first aspect of the present invention, since the lost motion mechanism is provided on the shift drum shaft, the shift drum and the lost motion mechanism can be supported by the support portion that supports the shift drum shaft, thereby reducing the number of support portions. The shift drum drive mechanism including the lost motion mechanism can be made compact and the number of parts can be reduced.

  According to the invention of claim 2, the lost motion mechanism and the input transmission member (shift drum shaft drive wheel) are arranged separately at both ends of the shift drum shaft, so that when these are concentrated on one side, As compared with this, it is possible to prevent the shift drum drive mechanism from being protruded in the axial direction and to make the shift drum drive mechanism more compact.

  According to the invention of claim 3, since the lost motion mechanism is provided adjacent to the shift drum, the length of the shift drum and the lost motion mechanism in the axial direction can be shortened, and the shift drum drive mechanism can be made more compact.

  According to the invention of claim 4, since the lost motion mechanism is used for the driving force transmission mechanism that is switched by a single shift fork, the shift drum can be reduced in size, and the axial length can be further shortened, and the shift can be performed. The drum drive mechanism can be made compact.

  According to the invention of claim 5, the shift drum shaft side contact portion that contacts the lost motion spring and the shift drum side contact portion that contacts the lost motion spring are provided between the lost motion spring and the shift drum. Therefore, not only can the axial length of the lost motion mechanism be shortened to make the shift drum drive mechanism more compact, but also the path for transmitting the rotation of the lost motion mechanism is shortened and the structure is simplified. it can.

  According to the invention of claim 6, since the position detector for detecting the position of the shift drum is arranged in the direction in which the central axis of the detector is orthogonal to the axial direction of the shift drum, the conventional technique of arranging in the coaxial direction is adopted. On the other hand, the shift drum drive mechanism can be reduced in size in the axial direction by preventing the detector from protruding in the axial direction.

  FIG. 1 is a side view of a motorcycle 1 having a power unit 2 according to an embodiment of the present invention. The motorcycle 1 includes a pair of main frames 4 that are connected to the head pipe 3 and are inclined downward and downward. The motorcycle 1 descends downward from the lower portion of the head pipe 3 and curves backward. A pair of sub-frames 5 connected to the section are provided.

  The power unit 2 in which the internal combustion engine 6 and the transmission 7 are integrated is mounted in a substantially triangular space formed by the main frame 4 and the sub frame 5. A front fork 8 is rotatably supported on the head pipe 3, a steering handle 9 is mounted on the upper end, and a front wheel 10 is pivotally supported on the lower end. A pair of rear forks 11 are pivotally supported at the rear portion of the main frame 4 and can swing in the vertical direction. A rear cushion (not shown) is mounted between the center portion of the rear fork 11 and the rear end portion of the main frame 4. A rear wheel 12 is pivotally supported at the rear end of the rear fork 11.

  The internal combustion engine 6 is a water-cooled V-type two-cylinder internal combustion engine, and the cylinder is opened in a V-shape in the front-rear direction. The crankshaft of the internal combustion engine 6 is orthogonal to the vehicle traveling direction and is arranged in the left-right direction of the vehicle. The transmission shaft of the transmission 7 is parallel to the crankshaft. The rear wheel drive shaft (not shown) is connected to a connecting shaft 85 (FIG. 2) perpendicular to the output shaft of the transmission, extends rearward of the vehicle, reaches the rotating shaft of the rear wheel 12, and To drive.

  The exhaust pipe 13 connected to the exhaust port of the two cylinders provided in the longitudinal direction of the vehicle extends to the front of the internal combustion engine 6, goes under the transmission 7 to the rear of the vehicle body, and is connected to the exhaust silencer 14. Has been. A fuel tank 17 is mounted on the upper part of the vehicle body frame 4, and a seat 18 is mounted behind the fuel tank 17. The internal combustion engine 6 is water-cooled, and the cooling water whose temperature has been raised in the course of cooling the cylinder and oil is cooled by a radiator 19 attached to the front surface of the sub-frame 5.

  FIG. 2 is a left side view of the power unit 2 mounted on the motorcycle. An arrow F points to the front when the vehicle is mounted (the same applies to other drawings). Since the front cylinder 24F and the rear cylinder 24R have the same internal structure, only the rear cylinder 24R is shown in cross section. The crankcase portion shows a state in which the left crankcase cover has been removed, and shows the positions of the main rotary shaft, gears and sprockets inside.

  3 is a developed sectional view taken along the line III-III in FIG. This figure is a developed view of a cross section including the rear cylinder 24R, the crankshaft 30, and the transmission shaft 66 of the hydrostatic continuously variable transmission 55. The rear cylinder 24R is a cylinder that holds a piston 33 connected to the left crankpin 31.

  2 and 3, the main outer shell of the power unit 2 is a crankcase 20 comprising a left crankcase 20L and a right crankcase 20R, a left crankcase cover 21L, a right crankcase cover 21R, and a front cylinder 24F and a rear cylinder. The cylinder block 25, the cylinder head 26, and the cylinder head cover 27 are provided for each of the side cylinders 24R. The cylinder portion described below will be described based on the rear cylinder 24R.

  In FIG. 3, a crankshaft 30 is rotatably supported by a left bearing 28 and a right bearing 29 held by left and right crankcases 20L and 20R. A connecting rod 32 and a piston 33 are connected to the left crank pin 31 of the crankshaft 30, and the piston 33 is slidably held in a cylinder hole 34 of the cylinder block 25. A combustion chamber 35 is formed in a portion of the cylinder head 26 that faces the piston 33, and a spark plug 36 that penetrates the wall of the cylinder head 26, has a front end facing the combustion chamber 35, and a rear end exposed to the outside. It is provided.

  In FIG. 2, an exhaust port 40 and an intake port 41 are connected to the combustion chamber 35. The exhaust port 40 extends forward in the front cylinder 24F and rearward in the rear cylinder 24R. The intake port 41 extends upward in the space between both cylinders in any cylinder. The exhaust port 40 is provided with an exhaust valve 42, and the intake port 41 is provided with an intake valve 43. Further, a cam shaft 44 is provided in the cylinder head cover 27, and an exhaust rocker arm shaft 45 and an intake rocker arm shaft 46 are provided above the cam shaft 44, and an exhaust rocker arm 47 provided on these arm shafts. The intake rocker arm 48 is driven by the cams 44a and 44b of the cam shaft 44, and pushes the stem tops of the exhaust valve 42 and the intake valve 43 to open and close the valves. 3, the camshaft 44 is driven by a camshaft drive chain 51 that is wound around a camshaft driven sprocket 49 provided at an end portion thereof and a camshaft drive sprocket 50 provided on a crankshaft 30.

  In FIG. 2, an oil pump assembly 90 in which a low pressure oil pump and a high pressure oil pump are integrated via an oil pump shaft 91 is provided at the lower part of the crankcase 20. The low pressure oil pump sends oil toward the internal combustion engine 6, and the high pressure oil pump sends oil toward the hydrostatic continuously variable transmission 55. The oil pump assembly sucks the oil in the oil pan 92 through the lower oil strainer 93. The oil pump assembly 90 is an internal combustion engine by an oil pump drive chain 96 wound around an oil pump shaft driven sprocket 94 fitted to the oil pump shaft 91 and an oil pump shaft drive sprocket 95 provided on the crankshaft 30. It is driven by the engine 6. An oil cooler 97 and a low pressure oil filter 98 are visible at the rear of the crankcase. The high pressure oil filter is not shown because it is provided on the right side of the crankcase.

  In FIG. 3, a crankshaft output gear 37 provided at the left end of the crankshaft 30 is a gear that functions in combination with an adjacent cam type torque damper 38, and is a swash plate type hydraulic pump 57 of the hydrostatic continuously variable transmission 55. Is engaged with a transmission input gear 60 that is integrally coupled to the casing 61. The crankshaft output gear 37 and the cam type torque damper 38 are configured on a collar 100 that is splined to the crankshaft 30. The crankshaft output gear 37 is rotatably fitted on the collar 100, and a concave cam 37a having an arcuate concave surface is formed on the side surface thereof. A lifter 101 is fitted to a spline on the outer periphery of the collar 100 so as to be movable in the axial direction. A convex cam 101a having an arcuate convex surface is formed on an end surface of the lifter 101, and the convex cam 101a meshes with the concave cam 37a. A spring holder 102 is fixed to the end of the collar 100 by a spline and a cotter. A disc spring 103 is provided between the spring holder 102 and the lifter 101 to urge the convex cam 101a toward the concave cam 37a.

  In the case of steady speed operation, the torque of the crankshaft 30 is transmitted in the order of the collar 100, the lifter 101, the convex cam 101a, the concave cam 37a, and the crankshaft output gear 37, and the crankshaft output gear 37 rotates together with the crankshaft 30. . When excessive torque is input to the crankshaft 30, the convex cam 101a slides in the circumferential direction on the cam surface of the concave cam 37a and moves in the axial direction against the biasing force of the disc spring 103 to absorb the excessive torque. And relieve shock.

  The crankshaft output gear 37 is a backlash reducing gear, and includes a thick main gear 104 at the center, a thin sub gear 105 held coaxially with respect to the main gear 104, and the sub gear 105. The auxiliary gear biasing coil spring 106 biases the main gear 104 in the circumferential direction. When the backlash reduction gear meshes with a normal gear, the secondary gear that is biased in the circumferential direction and closes out fills the backlash gap that occurs between the main gear and the normal gear. Reduced and quiet. In this case, the meshing between the crankshaft output gear 37 and the transmission input gear 60 is quiet.

  In FIG. 3, a hydrostatic continuously variable transmission 55 provided behind the crankshaft 30 combines a centrifugal governor clutch 56, a swash plate hydraulic pump 57, and a swash plate hydraulic motor 58 through a transmission shaft 66. Device. The casing 62 of the centrifugal governor clutch 56 is integrally connected to the casing 61 of the swash plate hydraulic pump 57. When the rotational speed of the casing 61 of the swash plate hydraulic pump 57 rises above a predetermined speed, a centrifugal weight 63 (for example, a steel roller or a steel ball) accommodated in the casing 62 of the centrifugal governor clutch 56 causes the moving member 64 to move. The hydraulic circuit switching rod 65 connected to this moves in the transmission shaft 66, closes the oil passage for circulating the discharge oil of the swash plate hydraulic pump 57 in the swash plate hydraulic pump 57, and The discharge oil of the pump 57 is switched to flow toward the swash plate hydraulic motor 58.

  The swash plate type hydraulic pump 57 and the swash plate type hydraulic motor 58 are connected at a gear ratio according to the inclination state of the swash plate 67 of the swash plate type hydraulic motor 58, and the rotational force thus changed is output to the output part of the swash plate type hydraulic motor 58. And a transmission output gear 68 fixed to a transmission shaft 66 integral with the transmission shaft 66. The inclination angle of the swash plate 67 of the swash plate type hydraulic motor 58 is changed by a swash plate drive mechanism (not shown) driven by an electric motor.

  4 is a cross-sectional view taken along the line IV-IV in FIG. This shows a power transmission path from the transmission shaft 66 to the connecting shaft 85. Parallel to the transmission shaft 66, the clutch shaft 76 of the neutral / drive switching clutch 75 for switching between the neutral state and the drive state is rotatably supported by the right crankcase 20R and the right crankcase cover 21R via ball bearings. ing. In parallel with the clutch shaft 76, an output shaft 80 is rotatably supported by the left crankcase 20L and the right crankcase 20R via ball bearings. Further, a connecting shaft 85 is rotatably supported by a connecting shaft support portion 84 provided near the left end portion of the output shaft 80 so as to be orthogonal to the output shaft 80. The connecting shaft support portion 84 is attached to the outside of the left crankcase 20L (see also FIG. 2).

  FIG. 5 is a cross-sectional view of the inside of the crankcase 20 as viewed from the right side with the right crankcase cover 21R removed. In the figure, the transmission shaft 66 of the hydrostatic continuously variable transmission 55, the clutch shaft 76 of the neutral drive switching clutch 75, the output shaft 80, and the neutral drive switching mechanism 110 can be seen.

  4 and 5, a gear 68 is fixed to the transmission shaft 66. A gear 77 is loosely fitted to the clutch shaft 76 so as to be rotatable with respect to the shaft. The gear 77 meshes with a transmission output gear 68 fixed to the transmission shaft 66. Adjacent to the gear 77, a sliding member 78 (FIG. 4) having engaging teeth 78a is loosely fitted to the clutch shaft 76 so as to be slidable in the axial direction. The clutch shaft 76, the gear 77, and the sliding member 78 constitute a neutral drive switching clutch 75 capable of intermittently transmitting power from the transmission shaft 66 to the output shaft 80. When the engaging tooth 78a of the sliding member 78 is disengaged from the gear 77, the neutral drive switching clutch 75 is not transmitted to the clutch shaft 76, so the power transmission path is cut off and the neutral drive state is established. When the sliding member 78 is slid along the clutch shaft 76 and the engaging teeth 78a are engaged with the engaging portion of the gear 77, the rotation of the gear 77 is transmitted to the clutch shaft 76. Connected and in drive state.

  In FIG. 4, a gear 79 is fitted on the clutch shaft 76 adjacent to the gear 77 on the side opposite to the sliding member 78 of the gear 77. A gear 81 that meshes with the gear 79 of the clutch shaft 76 is fitted to the right end of the output shaft 80 (see also FIG. 5). A bevel gear 82 is formed integrally with the other end of the output shaft 80. A bevel gear 86 is integrally formed at the front end of the connecting shaft 85 and meshes with the bevel gear 82 of the output shaft 80. A spline 85a is provided at the rear end of the connecting shaft 85 so that a rear wheel drive shaft (not shown) can be connected. By these shafts and gears, the rotational output of the hydrostatic continuously variable transmission 55 is transmitted to the rear wheel drive shaft.

  In FIG. 5, the neutral drive switching mechanism 110 includes a shift fork support shaft 111, a shift fork 112 rotatably supported on the support shaft 111, a shift drum shaft 121, a shift drum shaft driving wheel 113, a shift drum shaft. The shift drum shaft drive wire 114 and the stopper roller assembly 140 that are wound around the drive wheel 113 and whose ends extend obliquely upward are visible. The distal end of the shift drum shaft drive wire 114 is connected to a manual or electric neutral drive switching operation unit 115 (not shown). The neutral drive switching operation unit 115, the shift drum shaft drive wire 114, and the shift drum shaft drive wheel 113 constitute a shift drum shaft drive mechanism 118. FIG. 5 shows a neutral sensor 116 and a drive sensor 117 for detecting the drum rotation position.

  FIG. 6 is a developed sectional view of the neutral drive switching mechanism 110. This is a developed view taken along the line VI-VI in FIG. 5, and is a developed sectional view connecting the clutch shaft 76, the shift fork support shaft 111, the shift drum shaft 121, and the stopper roller assembly support bolt 141. The shift fork 112 that engages with the shift drum 132 through the guide pin 112a and moves in the axial direction of the clutch shaft 76 engages with the peripheral groove 78b of the sliding member 78 and pushes the sliding member 78 in the axial direction. Then, the sliding member 78 and the gear 77 are intermittently connected.

  7 is an enlarged cross-sectional view of the shift drum drive mechanism 120, FIG. 8 is a diagram in which the shift fork 112 and the neutral sensor 116 are added to the right side view of the shift drum 132 in FIG. 7, and FIG. 10 is a two-side view of the driven plate 134. FIG. 9A is a front view of the leading plate 133, and FIG. 9B is a view as viewed from the arrow B in FIG. 10A is a front view of the driven plate 134, and FIG. 10B is a cross-sectional view taken along the line BB in FIG.

  In FIG. 7, the shift drum drive mechanism 120 includes a shift drum shaft 121, a coil spring support cylinder 122, a washer 123, a bolt 124, a rotating member 130, a leading plate 133, a driven plate 134, and a lost motion coil spring 125. ing. The shift drum shaft 121 is rotatably supported by the right crankcase 20R and the right crankcase cover 21R (FIG. 6). One end of the shift drum shaft is a mounting portion for the shift drum shaft driving wheel 113. The central portion of the shift drum shaft 121 is a large diameter portion 121a, and the other end portion is a small diameter portion 121b. A pair of leading plate locking flat surfaces 121c are formed at the boundary between the large diameter portion 121a and the small diameter portion 121b, and the leading plate 133 (FIG. 9) is non-rotatably fitted to the shift drum shaft 121. . A coil spring support tube 122 is fitted to the small diameter portion 121b of the shift drum shaft 121, and is pushed and fixed in the axial direction by a bolt 124 via a washer 123. The leading plate 133 is pushed by the end surface of the coil spring support cylinder 122 and fixed to the shift drum shaft 121. A lost motion coil spring 125 is rotatably fitted around the periphery of the coil spring support tube 122 so as to be able to rotate.

  A rotating member 130 is rotatably mounted on the large diameter portion 121a of the shift drum shaft 121. The rotating member 130 is formed by integrally forming a boss portion 131 and a shift drum 132 that are long in the axial direction. The shift drum 132 formed at one end of the boss 131 of the rotating member 130 includes a cam groove 132a (FIGS. 7 and 8), and the guide pin 112a of the shift fork 112 slides in the cam groove 132a. (Fig. 8). A pair of driven plate locking flat surfaces 131a is formed at the other end of the boss portion (FIG. 7), and the driven plate 134 (FIG. 10) is fitted to the rotating member 130 so as not to rotate. . A stopper roller assembly 140 is provided below the shift drum drive mechanism 120 to stabilize the rotational position of the shift drum 132, and the stopper roller 144 is engaged with the outer periphery of the driven plate 134.

  The shift drum 132 is provided with a shift drum position detecting convex portion 132b, and the neutral sensor 116 and the drive are positioned at positions (FIGS. 5 and 8) that oppose the convex portion at the neutral position and the drive position of the shift drum 132. A sensor 117 is fixed to the right crankcase cover 21R. The sensor is arranged in a direction in which the central axis of the sensor is orthogonal to the axial direction of the shift drum. The position of the shift drum 132 is detected when the position detecting convex portion 132b comes into contact with any one of the sensor tip detecting portions.

  11 is a cross-sectional view taken along the line XI-XI of FIG. 7 when the shift drum is in the neutral state, FIG. 12 is a two-sided view of the lost motion coil spring 125, and FIG. 12A is an arrow of FIG. FIG. 12B is a view of the lost motion coil spring 125 viewed from the XII direction, and FIG. In FIG. 11, the shift drum shaft 121 and the leading plate 133 rotate together, and the rotation member 130 and the driven plate 134 rotate together. The shift drum shaft 121 and the rotation member 130 can be rotated relative to each other.

  In FIG. 12, two parallel leading leg portions 125a and driven leg portions 125b are formed at both ends of the lost motion coil spring 125. As shown in FIGS. 9 and 10, coil spring engaging convex portions for engaging the leg portions 125 a and 125 b of the lost motion coil spring 125 with the leading plate 133 and the driven plate 134, respectively. 133a and 134a are formed. The lost motion mechanism 126 is configured by the leading plate 133, the driven plate 134, and the lost motion coil spring 125.

  11, in the neutral state, the leading plate 133 is positioned according to the rotational position of the shift drum shaft 121 set in the neutral drive switching operation unit 115 (the tip of the wire 114 in FIG. 5). The coil spring engagement convex portion 133a is also positioned. The coil spring engaging convex portion 133a of the leading plate 133 and the coil spring engaging convex portion 134a of the driven plate 134 are strongly sandwiched between the leg portions 125a and 125b of the lost motion coil spring 125 (FIG. 12). The driven plate 134 that can rotate relative to the plate 133 is also positioned at the neutral position. As a result, in the drawing, the coil spring engaging convex portions 133a and 134a of both plates are overlapped. In FIG. 11, the coil spring engaging convex portion 134a of the driven plate is visible because it is on the near side, but the coil spring engaging convex portion 133a of the leading plate is not visible because it overlaps the other side. The shift drum 132 that rotates integrally with the driven plate 134 and the shift fork 112 that follows the shift drum 132 are also in the neutral position, and the neutral drive switching clutch 75 is disconnected. Next to the coil spring engaging convex portion 133a of the leading plate 133 (FIG. 9), a stopper convex portion 133b having a bent tip is provided. This is to prevent the unnecessary displacement of the leading plate 133 to one side by contacting the side surface of the coil spring engaging convex portion 134a of the driven plate 134.

  7 and 11, a stopper roller assembly 140 for stabilizing the shift drum rotation position is provided below the shift drum drive mechanism 120. The stopper roller assembly 140 is rotated by a support bolt 141 fixed to the right crankcase 20R, an arm 142 rotatably held around the support bolt 141, and a roller shaft 143 at the tip of the arm 142. An arm 142 is attached to press the stopper roller 144 against the peripheral surface of the star-shaped uneven portion 134b of the driven plate.The stopper roller 144 is held around the cylindrical member 145 held by the support bolt 141. A stopper roller urging coil spring 146 is provided. There are two concave portions of the star-shaped uneven portion 134b of the driven plate 134, the upper concave portion in FIG. 10 is a neutral corresponding concave portion 134N, and the lower concave portion is a drive corresponding concave portion 134D. They are separated by a central angle of 60 degrees. When the stopper roller 54 is fitted into and pressed against either the neutral or the concave portion of the driven plate 134 corresponding to the drive, the rotational position of the shift drum 132 that rotates integrally with the driven plate 134 is stably maintained. In FIG. 11, the stopper roller 144 is pressed against the neutral corresponding recess 134N, and the neutral position of the shift drum 132 is stably maintained.

  As described above, the neutral drive switching mechanism 110 includes the shift drum shaft driving mechanism 118, the shift drum driving mechanism 120, the lost motion mechanism 126, the shift fork 112, the neutral drive switching clutch 75, and the stopper roller assembly 140. Has been. Next, the operation of the lost motion mechanism 126 will be described.

  When the driver issues a drive command from the neutral state of FIG. 11 via a shift switch or the like provided on the steering wheel, the neutral drive provided at the end of the shift drum shaft drive wire 114 (FIGS. 5 and 6). In the switching operation unit 115, one of the shift drum shaft drive wires 114 is pulled, the shift drum shaft drive wheel 113 rotates, and the shift drum shaft 121 ( 6 and 7) rotate in the direction of arrow W in FIG. In this embodiment, since the cam groove 132a is designed so that the neutral drive can be switched when the shift drum 132 rotates 60 degrees, the neutral drive switching rotation angle of the shift drum shaft 121 is designed. Is also 60 degrees.

  The leading plate 133 connected to the shift drum shaft so as to rotate integrally is rotated 60 degrees in accordance with the rotation of the shift drum shaft 121. At this time, the coil spring engaging convex portion 133a of the leading plate 133 pushes one leading side leg portion 125a of the coil spring in the rotating direction. Since the other driven leg portion 125b of the coil spring is connected to the leading leg portion 125a via the coil portion 125c of the coil spring, the coil spring engaging convex portion 134a of the driven plate 134 is driven on the driven side of the coil spring 125. The coil spring engaging convex portions 133a and 134a of both plates are rotated by 60 degrees while being sandwiched between the leg portions 125a and 125b of the coil spring 125, and the shift drum 132 is also moved together therewith. It rotates 60 degrees and stops at the drive state position. The shift fork 112 moves in accordance with the rotation of the shift drum 132, and the power transmission path is connected by the neutral / drive switching clutch 75 to switch to the drive state.

  FIG. 13 is a cross-sectional view of shift drum drive mechanism 120 when the switching to the drive state is completed as described above. The coil spring engaging convex portions 133a and 134a of both plates are rotated 60 degrees from the neutral position. The stopper roller 144 is fitted and pressed into a drive-corresponding recess 134D provided 60 degrees apart from the neutral-corresponding recess 134N to stabilize the drive state.

  There is a case where the neutral drive switching is not smoothly performed for some reason, and the shift fork 112 and the shift drum 132 are instantaneously stopped. Even in this case, the shift drum shaft 121 can be rotated by the action of the lost motion mechanism 126 if there is a command from the neutral drive switching operation unit 115. That is, even if the driven plate 134 that rotates integrally with the shift drum 132 is in a stopped state, the leading plate 133 that rotates together with the shift drum shaft 121 can rotate. At this time, the coil spring engagement convex portion 133a of the leading plate 133 and the coil spring engagement convex portion 134a of the driven plate 134 are relatively rotated and separated from each other, whereby both the leg portions 125a and 125b of the lost motion coil spring 125 are also separated. The lost motion coil spring 125 is elastically deformed.

  FIG. 14 is a cross-sectional view of the shift drum drive mechanism 120 in a state where the coil spring engaging convex portions 133a and 134a of both plates rotate relative to each other and the legs 125a and 125b of the lost motion coil spring 125 are separated as described above. FIGS. 15A and 15B are two views of the lost motion coil spring 125 in an elastically deformed state, FIG. 15A is a view of the coil spring viewed from the direction of the arrow XV in FIG. 14, and FIG. It is a B arrow directional view of (a). The coil spring 125 is designed to be able to handle the relative rotation of the plates 133 and 134 by 60 degrees. Since the lost motion mechanism 126 functions as described above, if the neutral drive switching operation unit 115 connected to the shift drum shaft driving wire 114 is an electric type, an overload is applied to the electric motor. Is avoided. As described above, the coil spring engaging convex portions 133a and 134a of both plates 133 and 134 which are relatively rotated and separated from each other are made elastic so that the both engaging convex portions 133a and 134a of the lost motion coil spring 125 approach each other. Since the force acts, when the stop phenomenon as described above is canceled for some reason, the driven plate 134 is rotated to the position of the leading plate 133 by the elastic force, and the drive state is established.

  As described above, when the neutral drive switching operation is performed by the electric motor, even if the shift drum 132 is temporarily stopped, the operation of the lost motion mechanism 126 prevents the electric motor from being overloaded. In addition, even when the neutral drive switching operation is performed manually, it is possible to prevent an excessive load from being applied to the neutral drive switching operation unit 115. In this case, the neutral drive can be switched smoothly.

  The shift drum drive mechanism of the present invention can also be applied to a transmission that is used in a motorcycle and whose gear stage is switched according to the rotation of the shift drum that is driven by a driver's shift transmission operation. .

As described in detail above, the present embodiment provides the following effects.
(1) Since the lost motion mechanism is provided on the shift drum shaft, the shift drum and the lost motion mechanism can be supported by the support portion that supports the shift drum shaft, and the number of support portions can be reduced. The shift drum drive mechanism including the motion mechanism can be made compact, and the number of parts can be reduced.
(2) Since the lost motion mechanism and the input transmission member (shift drum shaft drive wheel) are arranged separately at both ends of the shift drum shaft, compared to the case where these are concentrated on one side, Protruding in the axial direction can be prevented, and further compactness can be achieved.
(3) Since the lost motion mechanism is provided adjacent to the shift drum, the axial lengths of the shift drum and the lost motion mechanism can be shortened to make the system more compact.
(4) Since the lost motion mechanism is used as a driving force transmission mechanism that is switched by a single shift fork, the shift drum can be miniaturized, and the axial length can be further shortened to make it compact. it can.
(5) Since the shift drum shaft side contact portion that contacts the lost motion spring and the shift drum side contact portion that contacts the lost motion spring are provided between the lost motion spring and the shift drum, Not only can the axial length of the motion mechanism be shortened to make it even more compact, but also the path for transmitting the rotation of the lost motion mechanism can be shortened and the structure can be simplified.
(6) Since the position detector for detecting the position of the shift drum is arranged in a direction in which the central axis of the detector is orthogonal to the axial direction of the shift drum, the detection is performed in comparison with the conventional technique arranged in the coaxial direction. It is possible to reduce the size of the device in the axial direction while preventing the container from protruding in the axial direction.

1 is a side view of a motorcycle including a power unit according to an embodiment of the present invention. It is a left view of the power unit mounted in the said motorcycle. FIG. 3 is a developed sectional view taken along the line III-III in FIG. 2. It is IV-IV sectional drawing of FIG. It is sectional drawing which looked at the inside of a crankcase from the right side. 2 is a cross-sectional development view of a neutral drive switching mechanism 110. FIG. 3 is an enlarged cross-sectional view of a shift drum drive mechanism 120. FIG. It is the figure which attached the shift fork to the right view of a shift drum. It is a 2nd page figure of a leading plate. It is a 2nd page figure of a driven plate. It is sectional drawing of the shift drum drive mechanism at the time of a neutral state. It is a 2nd page figure of a lost motion coil spring. It is sectional drawing of a shift drum drive mechanism when the switch to a drive state is completed. It is sectional drawing of the shift drum drive mechanism in the state in which both the leg parts of the lost motion coil spring are spaced apart. It is a 2nd view of the lost motion coil spring of the state which elastically deformed.

Explanation of symbols

110 ... Neutral drive switching mechanism, 112 ... Shift fork, 113 ... Shift drum shaft drive wheel, 114 ... Shift drum shaft drive wire, 115 ... Neutral drive switching operation unit, 116 ... Neutral sensor, 117 ... Drive sensor, 120 ... Shift drum drive mechanism, 121 ... shift drum shaft, 125 ... lost motion coil spring, 125a ... leading leg, 125b ... driven leg, 126 ... lost motion mechanism, 132 ... shift drum, 132a ... cam groove, 132b ... Shift drum position detecting convex part 133... Leading plate 133 a... Coil spring engaging convex part 134.

Claims (6)

In a vehicle shift drum drive mechanism used to cut off or connect a power transmission path in a driving force transmission mechanism, or to switch a gear position in a transmission,
A shift drum, a shift drum shaft that is inserted into the shift drum and rotatably supports the shift drum, and is rotatably supported by a plurality of support portions;
A vehicular shift drum drive mechanism comprising a lost motion mechanism provided on the shift drum shaft and transmitting the rotation of the shift drum shaft to the shift drum via a lost motion spring. The lost motion mechanism is disposed in the vicinity of an end portion of the other shift drum shaft with respect to an input transmission member (shift drum shaft driving wheel) provided at one end portion of the shift drum shaft. Item 2. The vehicle shift drum drive mechanism according to Item 1. 3. The vehicle shift drum drive mechanism according to claim 1, wherein the lost motion mechanism is provided adjacent to the shift drum. 4. The vehicle shift drum drive mechanism according to claim 1, wherein the lost motion mechanism is used in a drive force transmission mechanism that is switched by a single shift fork. A shift drum shaft side contact portion which is provided on the shift drum shaft so as to be integrally rotatable, and which contacts the lost motion spring;
A shift drum side contact portion that is provided so as to be integrally rotatable with the shift drum and that contacts the lost motion spring,
The vehicle shift drum drive mechanism according to claim 1, wherein the vehicle is provided between the lost motion spring and the shift drum. The position detector for detecting the position of the shift drum is arranged in a direction in which the central axis of the detector is orthogonal to the axial direction of the shift drum. Vehicle shift drum drive mechanism.

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