Abstract: A steering system includes a steering unit which can be configured to convert an operation input to an input shaft into an arbitrary amount of rotation or an arbitrary turning force and output the arbitrary amount of rotation or the arbitrary turning force from an output shaft. A steering handlebar can be configured to be coupled to the input shaft. A support bracket can be configured to be coupled to the output shaft and to support a front wheel of the vehicle. A housing can be configured to accommodate the steering unit. The steering unit can be configured to be mounted to a front end portion of a vehicle body frame of the vehicle integrally therewith by the housing.

Abstract: A steering system includes a steering unit which can be configured to convert an operation input to an input shaft into an arbitrary amount of rotation or an arbitrary turning force and output the arbitrary amount of rotation or the arbitrary turning force from an output shaft. A steering handlebar can be configured to be coupled to the input shaft. A support bracket can be configured to be coupled to the output shaft and to support a front wheel of the vehicle. A housing can be configured to accommodate the steering unit. The steering unit can be configured to be mounted to a front end portion of a vehicle body frame of the vehicle integrally therewith by the housing.

Abstract: A fuel supply port portion incorporates tank fittings such as a fuel pump and a residual fuel meter unit integrally therein as a tank fittings assembly. The fuel supply port portion is formed as a separate body from a tank body of a fuel tank and is removably attached to the tank body. The structure of the tank body can be simplified, and in the case where the tank body is made of a resin, it is not necessary to perform an insert molding operation. Consequently, it is possible to fabricate the tank body easily and also possible to thin the tank body, thereby ensuring a sufficient capacity of the fuel tank. Further, since tank fittings mounting portions are concentrated in the fuel supply port portion, it is possible to assemble the fuel tank in an efficient manner.

Abstract: A method and device are provided for adjusting the height of a motorcycle equipped with a motorcycle-height changing device for increasing and decreasing the height of the motorcycle in accordance with the operation of an actuator controlled in accordance with information on the speed of the motorcycle. Thus, an operational delay can be prevented from occurring when stopping the motorcycle by an abrupt deceleration. In addition, the height of the motorcycle can be increased to a high value quickly even at the time the motorcycle is started. A first piece of set speed information is set for starting the operation of the actuator to decrease the height of the motorcycle, and a second piece of set speed information different from the first set speed information is set for starting the operation of the actuator to increase the height of the motorcycle.

Abstract: A shock absorber link mechanism linking a rear shock absorber to a swing arm of a motorcycle is capable of varying the suspension height and the height of a vehicle. The shock absorber link mechanism includes a first link arm pivotally attached to the frame, a second link arm pivotally attached to a swing arm, a shock absorber link arm pivotally attached to the shock absorber, and an arm connecting shaft. A motor driven actuator varies the link ratio (height) and link form (load characteristic) of the shock absorber link mechanism by rotating the shock absorber link arm via a motion transmission member, pulley, sectoral gear and arm connecting shaft. Further, a sub-wire driven by the actuator compresses the shock absorber when the suspension is lowered.

Abstract: A target slippage ratio setting device has sensors respectively mounted on driven and driving wheels so as to detect rotational velocities thereof, a body accelerometer attached to a main body of a vehicle, a steering angle sensor mounted on a handle, and a control unit. In the target slippage ratio setting device, a target slippage ratio at which the optimum braking force is obtained, can be determined from a coefficient of friction calculated by a friction coefficient calculating circuit, a banking angle calculated by a banking angle calculating circuit and an estimated velocity of the vehicle calculated by an estimated vehicle velocity calculating circuit, based on the peripheral velocities of the front and rear wheels and the acceleration or deceleration of the vehicle.

Abstract: A brake control system for obtaining the optimal slippage ratio for stable braking of a vehicle, has a friction coefficient detecting device, a target slippage ratio setting device, a correction coefficient setting device and a target slippage ratio correcting device. The friction coefficient detecting device detects the coefficient of friction between each of wheels and a road surface. The target slippage ratio setting device sets up a target slippage ratio based on the coefficient of friction. The correction coefficient setting device detects the rate of change in the coefficient of friction and sets a first correction coefficient for calculating the target slippage ratio based on the rate of change in the coefficient of friction. The target slippage ratio correcting device multiplies the target slippage ratio by the first correction coefficient thereby to correct the target slippage ratio. Thus, the vehicle can be smoothly driven.

Abstract: A device for controlling the braking force of a motorcycle in two controlling modes: a normal mode and an antilocking mode, comprises tachometers mounted on front and rear wheels of the motorcycle, an accelerometer mounted on the motorcycle body, and a control circuit. The control circuit calculates a peripheral acceleration of each wheel based on the peripheral velocity of each wheel, and a slippage ratio of each wheel based on the peripheral velocity of the wheel and the acceleration of the motorcycle body. When the slippage ratio and the peripheral acceleration of one wheel meets given conditions, the control circuit starts, prior to entering into the antilocking mode from the normal mode, to calculate the coefficient of friction between the road surface and the one wheel. For the other wheel, the coefficient of friction is calculated in the same manner.

Abstract: A road surface condition sensor for judging if there is an appreciable unevenness on a road surface to provide a desirable braking performance for a vehicle, which comprises a vehicle speed estimating circuit for estimating the running speed of the vehicle, a steering angle sensor for detecting a steering angle of the vehicle, and a judging circuit for making a judgement as to whether the magnitude of a time-derivative of the steering angle indicative of the unevenness of a road surface is greater than a threshold value which is determined according to the estimated running speed of the vehicle, and for outputting a road surface condition signal representing results of the judgement.