Vehicle speed limiting system

A vehicle speed limiting system (40) having a throttle-by-wire mechanism that drives a throttle valve (28) using a motor (30),

• the vehicle speed limiting system comprising:
• a three-dimensional map (46a) that is provided to each of gear stages of a transmission (60) and from which to derive a target throttle valve opening degree (θB) of the throttle valve (28) on a basis of a throttle grip opening degree (θA) and an engine speed;
• a throttle valve driving unit (47) that drives the motor (30) in accordance with the target throttle valve opening degree,
• wherein, when a speed of a vehicle (1) is about to exceed a preset maximum speed, the throttle valve driving unit (47) drives the motor (30) in such a manner that the speed of the vehicle (1) does not exceed the preset maximum speed, irrespective of the target throttle valve opening degree (θB) derived from the three-dimensional map (46a), speed difference calculating means for calculating a difference between a current speed of the vehicle (1) and the preset maximum speed;
• acceleration calculating means for calculating an acceleration of the vehicle (1);
• and
• maximum speed limiter opening degree calculating means (43) for calculating a first maximum speed limiter opening degree by adding a first predetermined opening degree, a second predetermined opening degree, and a current throttle valve opening degree, the first predetermined opening degree being calculated by multiplying the speed difference by a preset P-term coefficient, the second predetermined opening degree being calculated by multiplying the acceleration by a preset D-term coefficient,
• wherein the throttle valve driving unit (47) is configured to drive the motor (30) on a basis of the first maximum speed limiter opening degree once the calculated first maximum speed limiter opening degree falls below the target throttle valve opening degree (θB) derived on a basis of the three-dimensional map (46a).