Methods and systems are provided for controlling an engine speed in a hybrid vehicle system during steady-state conditions and in response to transient acceleration and/or deceleration requests. In one example, an engine speed is controlled to an optimal engine speed for fuel economy during steady-state conditions, and in response to an acceleration or deceleration request, a target engine speed is obtained from a rate-limited optimal engine speed to vehicle speed ratio, and the engine is controlled to the target engine speed provided the target speed is below a threshold difference from optimal engine speed. In this way, the vehicle system may simulate a fixed ratio transmission during accelerations and decelerations, while maintaining optimal engine speed for fuel economy at steady state.

A hybrid vehicle includes an engine, a motor, and a belt stepless speed changer device having a driving rotary body, a driven rotary body, a first shaft member supporting the driving rotary body with allowing rotation thereof in unison, a second shaft member supporting the driven rotary body with allowing rotation thereof in unison, and an endless belt wound around the driving rotary body and the driven rotary body. The vehicle further includes a transmission case configured to receive the powers from the engine and the motor via the belt stepless speed changer device and a centrifugal clutch incorporated in a power transmission line extending form the engine to the first shaft member. The motor is disposed on the side opposite the engine across the driving rotary body, and the driving power of the motor is inputted to the first shaft member.

A shifting control method for a hybrid vehicle may include motor torque determination step, of determining the condition of a motor torque, by a controller, in a power-off downshift shifting process, gear mesh step, by the controller, of releasing a clutch of a releasing side and meshing a target shifting stage gear connected to a clutch of engaging side when the motor torque is positive (+) torque, an assist control step, of controlling, by the controller, the motor torque to 0 Nm, a rising step, by the controller, of controlling the motor speed to rise and follow a target motor speed predetermined higher than at least an input shaft speed of an engaging side after releasing the assist control, and an engaging step, by the controller, of engaging the clutch of the engaging side by a clutch torque of the engaging side when the motor speed exceeds the input shaft speed of the engaging side.

The present disclosure provides a shift control method for a hybrid electric vehicle including: controlling a speed of a vehicle driving source; simultaneously controlling a release element and a connection element in a transmission based on a rotation acceleration of a transmission output shaft when shifting by a power-on down shift.

A method of shifting ranges within a transmission is provided. The method of an embodiment includes determining an intention to change from a first mode to a second mode in the transmission, determining the first mode of the transmission, which includes a first range clutch in an engaged condition and a first synchronizer in a first engaged condition, determining the second mode of the transmission, which includes a second range clutch in an engaged condition and a second synchronizer in a first engaged condition, engaging the second synchronizer in the first engaged condition, disengaging the first range clutch, engaging the second range clutch, and disengaging the first synchronizer from the first engaged condition.

Provided is a control device for a vehicle. A control device for a vehicle includes a vehicle that includes an engine and a main motor, and a transmission equipped with first and second input shafts which are respectively connected to the engine via first and second clutches, an output shaft through which power is output to drive wheels, first and second transmission mechanisms which respectively includes a plurality of transmission gears selectively joined to the first and second input shaft respectively, and an ECU. When the main motor is driven and when the engine is stopped, the ECU determines that the vehicle travels using power of the engine using the transmission gears of one of transmission mechanisms in a case where defective engagement release occurs such that a transmission gear of the other transmission mechanism is not disengaged.

A hybrid electric vehicle which may effectively determine a point in time of shift pattern change and a method of controlling a shift pattern therefor are disclosed. The method includes determining whether or not a request for shift pattern change is received, determining HEV mode related conditions, in response to a determination that the request for shift pattern change is received, and changing a shift pattern according to the request for shift pattern change, in response to a determination that the HEV mode related conditions are satisfied.

A shift strategy is provided for a hybrid electric vehicle to cause a speed of a motor to approach a target motor speed to increase fuel economy for an engine operating in a hybrid drive mode. A controller shifts the transmission according to a magnitude of a driver torque demand, the current rotor or impeller speed, and whether the motor is consuming or producing current. The controller shifts the transmission according to one shift schedule when the motor is motoring, and according to another shift schedule when the motor is generating power.

Disclosed herein is a technique for improving drivability of a vehicle by controlling the driving of the vehicle by a double clutch when the clutch of a double clutch transmission (DCT) is overheated. There is provided a shift control method for a hybrid vehicle with a DCT. In particular, where it is desired to perform shifting when one of clutches of the DCT is overheated, double-clutch shifting is performed using a non-overheated clutch and an engine clutch without using the overheated clutch, thereby reducing disharmonic shifting in virtue of a small difference in gear ratio during shifting and improving shifting and driving performance.

An electronic control unit of a hybrid vehicle controls an engine and an inverter to execute inverterless traveling. The inverterless traveling is a traveling state where the inverter is set to a gate blocking state, and where a reaction force of a torque that is output by a rotating electric device when the rotating electric device to be rotated by output of the engine generates electric power is applied to an output shaft. The electronic control unit controls a converter to adjust a voltage of an electric power line to a predetermined maximum voltage or a voltage within a predetermined range from the maximum voltage when a shift range of the hybrid vehicle is switched to a non-forward range from a forward range during the inverterless traveling.