Constant mesh type transmission for straddled vehicle with ratchet mechanism

A constant-mesh type transmission for a straddled vehicle, the transmission being configured to be mounted on the straddled vehicle, the transmission comprising:

• an input shaft disposed to be rotatable around a first axis line, and configured to receive power from a crankshaft;
• a plurality of drive gears disposed on the input shaft so as to be coaxial with the input shaft;
• an output shaft disposed to be rotatable around a second axis line that is parallel to the first axis line;
• a plurality of driven gears disposed on the output shaft so as to be coaxial with the output shaft and rotatable relative to the output shaft, the plurality of driven gears being constantly meshed respectively with the plurality of drive gears, to respectively correspond to a plurality of gear stages;
• and
• a gear stage setting mechanism that mechanically and selectively sets power transmission active from the input shaft to the output shaft at any of the plurality of gear stages, via one of the plurality of drive gears and one of the plurality of driven gears corresponding to said any gear stage, wherein
• the gear stage setting mechanism includes a ratchet mechanism that mechanically sets the power transmission from one of any two of the plurality of driven gears, respectively in adjacent two of the plurality of gear stages, to the output shaft,
• said adjacent two of the plurality of gear stages are respectively a lower gear stage and a higher gear stage that is higher than the lower gear stage,
• said any two of the plurality of driven gears are respectively a lower-speed driven gear and a higher-speed driven gear, corresponding respectively to the lower gear stage and the higher gear stage, and
• the ratchet mechanism includes
• a set of pawls disposed at different positions with respect to a direction of the second axis line, the set of pawls being respectively
• a lower-speed accelerating pawl that is pivotable so as to, when raised, allow acceleration-directed power passing through the lower-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the acceleration-directed power to be transmitted to the output shaft;
• a lower-speed decelerating pawl that is pivotable so as to, when raised, allow deceleration-directed power passing through the lower-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the deceleration-directed power to be transmitted to the output shaft;
• a higher-speed accelerating pawl that is pivotable so as to, when raised, allow the acceleration-directed power passing through the higher-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the acceleration-directed power to be transmitted to the output shaft;
• and
• a higher-speed decelerating pawl that is pivotable so as to, when raised, allow the deceleration-directed power passing through the higher-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the deceleration-directed power to be transmitted to the output shaft;
• a rotary cam located inside the output shaft so as to be coaxial with the output shaft, the rotary cam being configured to rotate in an up-shift direction and a down-shift direction, which are opposite to each other, respectively according to an up-shift operation and a down-shift operation of the constant-mesh type transmission, the rotary cam having, on an outer peripheral surface thereof,
• a lower-speed position and a higher-speed position, which are different from each other in a circumferential direction of the rotary cam and respectively correspond to the lower gear stage and the higher gear stage, and
• a plurality of cam portions respectively corresponding to the set of pawls, each of the plurality of cam portions extending on the outer peripheral surface of the rotary cam in the circumferential direction thereof between the lower-speed position and the higher-speed position;
• and
• a plurality of sliders respectively corresponding to the set of pawls, each of the plurality of sliders having a guide object part that is guided by one of the plurality of cam portions, and being movable between a pawl-raising position and a pawl-lowering position in the direction of the second axis line, to thereby raise or lower one of the set of pawls corresponding thereto, wherein
• the plurality of cam portions are so formed that a rotation of the rotary cam in the up-shift direction and the down-shift direction causes the plurality of cam portions to guide the plurality of guide object parts to respectively move in an up-shifting movement path and a down-shifting movement path, to thereby move the set of pawls in predetermined sequences, the up-shifting and down-shifting movement paths being different from each other,
• each of the plurality of cam portions of the rotary cam is a cam groove, and has a lowered-direction drive surface and a raised-direction drive surface, the lowered-direction drive surface allowing one of the sliders corresponding to said each cam portion to move from the pawl-raising position thereof to the pawl-lowering position thereof by relative rotation between the rotary cam and the guide shaft, the raised-direction drive surface allowing the one of the sliders corresponding to said each cam portion to move from the pawl-lowering position thereof to the pawl-raising position thereof by the relative rotation between the rotary cam and the guide shaft,
• the guide shaft has a plurality of guide holes respectively corresponding to the plurality of cam grooves, the plurality of guide holes penetrating through the guide shaft in a diameter direction of the guide shaft and being formed such that a length of each guide hole in an axis line direction of the guide shaft is longer than a length of the guide hole in a circumferential direction of the guide shaft,
• the plurality of guide object parts extend in the diameter direction of the guide shaft so as to respectively pass through the plurality of guide holes and be received in the plurality of cam grooves,
• the output shaft has a plurality of through holes respectively corresponding to the set of pawls, the plurality of through holes being formed so as to penetrate through the output shaft in a diameter direction of the output shaft, and
• the ratchet control mechanism further includes a plurality of balls that are respectively received in the plurality of through holes of the output shaft, the plurality of balls being configured such that,
• when any of the plurality of sliders moves to the pawl-lowering position thereof, one of the balls that abuts against said any slider moves outward with respect to the diameter direction of the output shaft, so that one of the set of pawls corresponding to said any slider is lowered, and,
• when said any slider moves to the pawl-raising position thereof, said one of the plurality of balls moves inward with respect to the diameter direction of the output shaft, so that said one of the set of pawls is raised.

A constant-mesh type transmission for a straddled vehicle, the transmission being configured to be mounted on the straddled vehicle, the transmission comprising:

• an input shaft disposed to be rotatable around a first axis line, and configured to receive power from a crankshaft;
• a plurality of drive gears disposed on the input shaft so as to be coaxial with the input shaft;
• an output shaft disposed to be rotatable around a second axis line that is parallel to the first axis line;
• a plurality of driven gears disposed on the output shaft so as to be coaxial with the output shaft and rotatable relative to the output shaft, the plurality of driven gears being constantly meshed respectively with the plurality of drive gears, to respectively correspond to a plurality of gear stages;
• and
• a gear stage setting mechanism that mechanically and selectively sets power transmission active from the input shaft to the output shaft at any of the plurality of gear stages, via one of the plurality of drive gears and one of the plurality of driven gears corresponding to said any gear stage, wherein
• the gear stage setting mechanism includes a ratchet mechanism that mechanically sets the power transmission from one of any two of the plurality of driven gears, respectively in adjacent two of the plurality of gear stages, to the output shaft,
• said adjacent two of the plurality of gear stages are respectively a lower gear stage and a higher gear stage that is higher than the lower gear stage,
• said any two of the plurality of driven gears are respectively a lower-speed driven gear and a higher-speed driven gear, corresponding respectively to the lower gear stage and the higher gear stage, and
• the ratchet mechanism includes
• a set of pawls disposed at different positions with respect to a direction of the second axis line, the set of pawls being respectively
• a lower-speed accelerating pawl that is pivotable so as to, when raised, allow acceleration-directed power passing through the lower-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the acceleration-directed power to be transmitted to the output shaft;
• a lower-speed decelerating pawl that is pivotable so as to, when raised, allow deceleration-directed power passing through the lower-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the deceleration-directed power to be transmitted to the output shaft;
• a higher-speed accelerating pawl that is pivotable so as to, when raised, allow the acceleration-directed power passing through the higher-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the acceleration-directed power to be transmitted to the output shaft;
• and
• a higher-speed decelerating pawl that is pivotable so as to, when raised, allow the deceleration-directed power passing through the higher-speed driven gear to be transmitted to the output shaft and, when lowered, not allow the deceleration-directed power to be transmitted to the output shaft;
• a rotary cam located inside the output shaft so as to be coaxial with the output shaft, the rotary cam being configured to rotate in an up-shift direction and a down-shift direction, which are opposite to each other, respectively according to an up-shift operation and a down-shift operation of the constant-mesh type transmission, the rotary cam having, on an outer peripheral surface thereof,
• a lower-speed position and a higher-speed position, which are different from each other in a circumferential direction of the rotary cam and respectively correspond to the lower gear stage and the higher gear stage, and
• a plurality of cam portions respectively corresponding to the set of pawls, each of the plurality of cam portions extending on the outer peripheral surface of the rotary cam in the circumferential direction thereof between the lower-speed position and the higher-speed position;
• and
• a plurality of sliders respectively corresponding to the set of pawls, each of the plurality of sliders having a guide object part that is guided by one of the plurality of cam portions, and being movable between a pawl-raising position and a pawl-lowering position in the direction of the second axis line, to thereby raise or lower one of the set of pawls corresponding thereto, wherein
• the plurality of cam portions are so formed that a rotation of the rotary cam in the up-shift direction and the down-shift direction causes the plurality of cam portions to guide the plurality of guide object parts to respectively move in an up-shifting movement path and a down-shifting movement path, to thereby move the set of pawls in predetermined sequences, the up-shifting and down-shifting movement paths being different from each other, and
• the rotary cam is so configured that
• in a case that the transmission is at the lower gear stage without shifting, the rotary cam is held at the lower-speed position, to thereby cause the lower-speed accelerating pawl and the lower-speed decelerating pawl to remain raised, and the higher-speed accelerating pawl and the higher-speed decelerating pawl to remain lowered;
• in a case that the transmission is at the higher gear stage without shifting, the rotary cam is held at the higher-speed position, to thereby cause the higher-speed accelerating pawl and the higher-speed decelerating pawl to remain raised, and the lower-speed accelerating pawl and the lower-speed decelerating pawl to remain lowered;
• in a case of shifting up from the lower gear stage to the higher gear stage, the rotary cam rotates in the up-shift direction from the lower-speed position to the higher-speed position, thus performing a first ratchet operation of sequentially
• lowering the lower-speed decelerating pawl,
• raising the higher-speed accelerating pawl and the higher-speed decelerating pawl, and
• lowering the lower-speed accelerating pawl;
• and
• in a case of shifting down from the higher gear stage to the lower gear stage, the rotary cam rotates in the down-shift direction from the higher-speed position to the lower-speed position, thus performing a second ratchet operation of sequentially
• lowering the higher-speed accelerating pawl,
• raising the lower-speed accelerating pawl and the lower-speed decelerating pawl, and
• lowering the higher-speed decelerating pawl.