Clutch operation assisting device, power unit for vehicle and straddle type vehicle including the same

A clutch operation-assisting device disposed in a clutch operation device, and housed in a casing of a power unit, the clutch operation device including a friction clutch having a pressure plate and a clutch spring that urges the pressure plate, the friction clutch being arranged in the casing of the power unit, the clutch operation device further including an operation element that is connected to the friction clutch through a transmission member, and is manually operated against an urging force of the clutch spring when torque transmission by the friction clutch is to be disengaged, the clutch operation-assisting device comprising:

• a sliding member that rotatably supports the pressure plate and slides in a predetermined direction together with the pressure plate;
• a first rotation member that is connected to the transmission member and slides the sliding member by rotating along with the transmission member;
• a support plate that rotatably supports the first rotation member;
• an auxiliary elastic member that changes an expansion direction and provides an urging force to rotate the first rotation member in a direction that disengages the friction clutch when the operation element is operated in a direction that disengages the friction clutch, while the operation element shifts from a disengagement starting position where the operation element receives a counter force of the clutch spring to a disengagement position where disengagement of the friction clutch is completed the expansion direction of the auxiliary elastic member does not pass through a rotation center of the pressure plate, as seen from a sliding direction of the sliding member, and the expansion direction of the auxiliary elastic member being offset from the rotation center of the pressure plate in both an operated position and a return position of the operating element;
• a second rotation member that is connected to the auxiliary elastic member and connected to the first rotation member at a connection position, and transmits the urging force of the auxiliary elastic member to the first rotation member by rotation;
• and
• a bearing member that is fixed to the support plate or integrally formed in the support plate, and rotatably supports the second rotation member,
• wherein the casing has a cover that covers the first rotation member from an outside of the clutch operation-assisting device, and
• further wherein a part of the first rotation member proximate the connection position bends away from the cover as the part approaches the connection position.