Transmission system for a straddle type vehicle

A semi-automatic transmission system for a straddle type vehicle which comprises a body frame supported by front and rear wheels, a seat supported above said frame and a power unit supported by said frame below said seat, said transmission system comprised in said power unit and includes:

• a switching means with an up-shift and a downshift button mounted on a steering bar wherein in operation depression of said up-shift button generates an input UO and depression of said downshift button generates an input DO;
• a transmission clutch mounted on one end of a main shaft of an engine;
• a transmission having at least two speed gear trains wherein a shifter means is mounted for charging from one speed gear train to another speed gear train:
• a shift actuating means for operating said shifter means;
• a clutch actuating means for operating said transmission clutch;
• a modulated controlling means connected to the clutch actuating means;
• an Electronic Control Unit (ECU) connected to said shift actuating means, said clutch actuating means and said modulated controlling means;
• wherein, in operation an input N is provided to said ECU and is proportional to the speed of said engine, an input V is provided to said ECU which varies with speed of the vehicle and
• (a) while cue of inputs UO and Do is read by the ECU, said clutch and said shift actuating means are activated by said ECU wherein said transmission clutch is disengaged while shifting is accomplished by said shifter means;
• said shifter means being moved and positioned to either speed gear train based on the generated input;
• and
• (b) said ECU reading said inputs N and V, said ECU deactivates said clutch and said shift actuating means and activates said modulated controlling means wherein an appropriate amount of slippage is permitted between said transmission clutch and said main shaft of said engine during engagement of said transmission clutch.

An automatic transmission system for a straddle type vehicle which comprises a body frame supported by front and rear wheels, a seat supported above said frame and a power unit supported by said frame below said seat, said transmission system comprised in said power unit and includes:

• a transmission clutch mounted on one end of a main shaft of an engine, said engine when activated, producing an input N indicative of engine speed and a throttle opening input A indicative of said throttle opening;
• a transmission having at least two speed gear trains wherein a shifter means is mounted for changing from one speed gear train to another speed gear train;
• a positioning means for determining the position of the shifter means, said positioning means generating an input T;
• a shift actuating means for operating said shifter means;
• a clutch actuating means for operating said transmission clutch;
• a modulated controlling means connected to the clutch actuating means;
• an Electronic Control Unit (ECU), corrected to said shift actuating means, said clutch actuating means and said modulated controlling means;
• wherein, in operation, said input N is provided to said ECU, an input V is provided to said ECU which varies with the speed of the vehicle and
• (a) while said ECU is reading input T and determines said input N being between two predetermined values, said input A being between two predetermined values, and said input V having reached a predetermined value;
• said clutch and said shift actuating means are activated by said ECU wherein said transmission clutch is disengaged while shifting is accomplished by said shifter means;
• said shifter means being moved and positioned to either gear train based on the generated input;
• and
• (b) while input T is read by the ECU and indicates shifting is complete, said ECU reads said inputs N and V and deactivates said clutch actuating means and said shift actuating means, and activates said modulated controlling means wherein an appropriate amount of slippage is permitted between said transmission clutch and said main shaft during engagement of said transmission clutch.