Patent ID: 8701813
Filing Date: 2014-04-22
Classification: F01N,F02D

Abstract:
1. A two-wheeled motor vehicle, comprising: a body frame; an engine mounted to the body frame for driving a rear wheel; an exhaust passage extending from the engine for discharging exhaust gas from the engine; a muffler provided at an outlet of the exhaust passage for reducing exhaust noise; an intake passage connected to the engine for supplying intake air into the engine; a throttle valve disposed in the intake passage for adjusting the amount of fuel gas to be supplied to the engine; a throttle grip rotatable by the driver to change the degree of opening of the throttle valve; and a noise-reduction device which, when a throttle ratio which is a ratio of the angle of operation of the throttle grip to a maximum rotation angle of the throttle grip is between zero and a predetermined value, reduces noise emitted from the engine, wherein said noise-reduction device comprises a control unit configured to achieve a noise reduction effect most efficiently when the following three conditions are fulfilled: (a) the vehicle speed is within a predetermined speed range, (b) a variation in speed is equal to or smaller than a predetermined value, and (c) the throttle ratio is within a predetermined range wherein the noise reduction device comprises an exhaust valve connected to and driven by the throttle grip via a cable, the exhaust valve being configured to change a cross-sectional area of the exhaust passage and also to reduce the noise most efficiently when the exhaust valve has a minimum degree of opening, wherein the noise-reduction device further comprises a lost motion mechanism incorporated in the cable between the throttle grip and the exhaust valve and configured to provide a lag in motion transmitted from the throttle grip to the exhaust valve such that when the throttle ratio is in a range of from zero to the predetermined value, the exhaust valve continues to retain the minimum degree of opening, and wherein the lost motion mechanism is switchable between an operable state and a disabled state, and the lost motion mechanism includes an electromagnetic valve configured to switch the lost motion mechanism between the operable state and the disabled state.