A vehicle includes an all-wheel-drive powertrain having an electric machine configured to power wheels. A controller is programmed to output a first calculated vehicle speed derived from integrating a measured longitudinal acceleration of the vehicle and output a second calculated vehicle speed based on the measured longitudinal acceleration and a speed of one of the wheels. The controller is further programmed to, responsive to a flag being present, command a speed to the electric machine that is based on the first vehicle speed to reduce wheel slip, and responsive to a flag not being present, command a speed to the electric machine that is based on the second vehicle speed to reduce wheel slip.

Provided is a master cylinder unit including a communication path that causes a master cylinder and a stroke simulator to communicate with each other. The stroke simulator includes a bottomed tube-shaped simulator piston and a simulator cylinder in which a simulator piston slides. The simulator piston is such that a bottom portion of the simulator cylinder and an opening portion of the simulator piston face each other. The communication path is open over an outer circumferential portion and an inner circumferential portion of the opening portion of the simulator piston, is connected to the bottom portion of the simulator cylinder, and is provided such that the communication path extends upward in a vertical direction from the bottom portion of the simulator cylinder as approaching to a pressure chamber.

Provided is a master cylinder unit including a communication path that causes a master cylinder and a stroke simulator to communicate with each other. The stroke simulator includes a bottomed tube-shaped simulator piston and a simulator cylinder in which a simulator piston slides. The simulator piston is such that a bottom portion of the simulator cylinder and an opening portion of the simulator piston face each other. The communication path is open over an outer circumferential portion and an inner circumferential portion of the opening portion of the simulator piston, is connected to the bottom portion of the simulator cylinder, and is provided such that the communication path extends upward in a vertical direction from the bottom portion of the simulator cylinder as approaching to a pressure chamber.

The embodiments of the present application disclose a stability control system and a stability control method for a four-wheel drive electric vehicle and the four-wheel drive electric vehicle. In the stability control system, when the lateral acceleration is equal to or greater than an acceleration threshold, at least one of a first braking force signal, a second braking force signal, a first logic signal and a second logic signal is obtained. When the first logic signal is obtained, the body of the electric vehicle is controlled to keep stable. When the first braking force signal and the second logic signal are obtained, a motor is controlled to apply braking force to an outside front wheel. When the second braking force signal and the second logic signal are obtained, motors are controlled to apply braking force to the outside front wheel and an inside rear wheel.

A control device of a four-wheel drive vehicle that includes a central axle disposed between paired left and right control couplings and coupled to the paired control couplings and that is switched between a two-wheel drive state and a four-wheel drive state selects between provision and stop of a slip prevention control in which when at least one of the main drive wheel slips during running of the vehicle, a brake is automatically operated to the at least one slipping main drive wheel, and when the stop of the slip prevention control is selected and it is detected that the at least one main drive wheel has slipped in the four-wheel drive state, a rotation speed of the central axle is made lower than that at the time of detection of the slip of the at least one main drive wheel.

An apparatus for controlling a four-wheel drive vehicle includes a tire friction circle calculator that calculates the size of a tire friction circle of each wheel on the basis of vehicle information including a tire vertical load, a resultant force calculator that calculates the magnitude of a resultant force of tire lateral and longitudinal forces for each wheel, a tire-friction-force usage rate calculator that calculates a tire-friction-force usage rate of each wheel that is the ratio of the magnitude of the resultant force to the size of the tire friction circle, and a driving-braking force adjustment controller that adjusts driving force or braking force applied to each wheel. When the tire-friction-force usage rate of any wheel exceeds a predetermined threshold of less than one, the driving-braking force adjustment controller restrains an increase in the driving force or the braking force of the wheel while increasing the driving force or the braking force of at least one of the other wheels that is selected on the basis of driving operation information indicative of the state of a driving operation by a driver.

A method for updating a vehicle reference speed for a vehicle is disclosed. The method includes increasing brake pressure to at least one wheel of the plurality of wheels and determining, via an electronic control unit, that a first wheel speed of the at least one wheel is less than a second wheel speed of another wheel of the plurality of wheels. The method also includes estimating the vehicle reference speed of the vehicle based upon the first wheel speed of the at least one wheel.

A vehicle includes a pair of electric machines each coupled to a laterally-opposing wheel to output a wheel torque. The vehicle also includes a controller programmed to command a combined regenerative braking torque output of the electric machines based on a lesser of a braking torque limit of each individual electric machine. The controller is also programmed to command a regenerative braking torque from each electric machine to be within a predetermined torque threshold of each other in response to a yaw rate exceeding a yaw threshold.

A vehicle includes a pair of electric machines each coupled to a laterally-opposing wheel to output a wheel torque. The vehicle also includes a controller programmed to command a combined regenerative braking torque output of the electric machines based on a lesser of a braking torque limit of each individual electric machine. The controller is also programmed to command a regenerative braking torque from each electric machine to be within a predetermined torque threshold of each other in response to a yaw rate exceeding a yaw threshold.

A control apparatus for a four-wheel drive vehicle is configured to acquire wheel speed differences, which are differences between wheel speeds of respective wheels and a reference speed, and execute traction control of causing a braking device to apply braking forces to wheels having wheel speed differences equal to or more than a predetermined control start value, the control apparatus being configured to, when a temperature of an actuator in a hydraulic circuit of the braking device is equal to or higher than a predetermined first temperature threshold value, select, as the reference speed, a wheel speed higher than a wheel speed that is selected as the reference speed when the temperature of the actuator is lower than the first temperature threshold value.