A hydraulic control device for a vehicle is provided wherein a determination of “base neutral” is made when a difference between a command hydraulic pressure and an actual hydraulic pressure of a hydraulic clutch is within a predetermined minute value range, and when the difference is out of the minute value range, a determination of “base raising” is made if the command hydraulic pressure is larger than the actual hydraulic pressure, and a determination of “base lowering” is made if the command hydraulic pressure is smaller than the actual hydraulic pressure. The determination of “sub raising” is made when an inclination of command torque subjected to low-pass filter processing is positive for a predetermined time or more, and the determination of “sub lowering” is made when the inclination is negative for the predetermined time or more, whereby a rising or dropping tendency of the command torque is determined.

A drive device includes: an actuator rotating, around a rotation axis, a shift drum having a lead groove formed on an outer peripheral surface; and an angle correction unit correcting a detection value of a rotation angle sensor that detects a rotation angle of the shift drum. The angle correction unit calculates the rotation angle of the shift drum at a reference position as a learning angle based on a correspondence between a displacement amount of a first engaging portion and a change amount of the rotation angle of the shift drum per a predetermined time of rotation of the shift drum at a predetermined speed. Then, the angle correction unit corrects the detection value of the rotation angle sensor based on an amount of deviation between the learning angle and a design angle.

A transmission combination includes a hydrostatic transmission and a mechanical transmission having a clutch and a control device for calibrating a grinding point of the clutch. A traction drive includes the transmission combination. A method includes calibrating the clutch.

A method is provided for calibrating a control algorithin of a clutch control unit of a vehicle. The method includes requesting, clutch disengagement, or engagement, monitoring clutch actuator position, determining a time interval that starts with the clutch disengagement or engagement request and ends when the clutch actuator has reached a predetermined position, and calibrating an estimated time interval of the control algorithm starting with clutch disengagement or engagement bequest and when the clutch actuator has reached a predetermined position based on the determined time interval. A computer program for implementing the method, as well as a vehicle comprising a clutch control unit calibrated according to the method, are also provided.

This clutch control device is provided with: a supply valve and a supply valve control unit, which control the supply of an operating fluid to a pressure chamber; a first discharge valve and a first discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber; and a second discharge valve and a second discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber. When it is determined that the engagement and disengagement switching of a clutch device 2, which is necessitated by the discharge of the operating fluid in the pressure chamber, is required, the first discharge valve is controlled to be opened and then the second discharge valve is controlled to be opened.

Controlling a clutch by means of an actuator, wherein at least one first shaft can be torque-transmittingly connected to a second shaft by means of the clutch, the clutch in one of at least three states, where in an disengaged first state, a torque cannot be transmitted, in a second state, a torque can be transmitted such that the speeds of the first shaft and the second shaft are synchronized in the second state, and in an engaged third state, a required torque can be transmitted; wherein, in various states and in an operating mode associated with the particular state, the actuator is adjusted at a different speed in order to adjust the clutch.

A control method of a clutch for a vehicle may include determining whether or not learning of clutch characteristics is possible; learning the clutch characteristics when the learning of the clutch characteristics is possible; determining a clutch torque for controlling the clutch in consideration of a change amount in the clutch torque before and after the learning and controlling the clutch by the determined clutch torque; and determining whether or not it is difficult to continue to learn the clutch characteristics.

A method sets a predefined position of a clutch actuator comprising a friction spring element. An activation path of the clutch actuator that actuates the clutch is predefined by a coupling torque via a coupling characteristic curve, wherein the predefined position (zo, zu) to be assumed by the clutch actuator is set by a closed-loop controller. To enable the predefined position of the clutch actuator to be set precisely without using additional energy, the predefined position (zo, zu) is corrected by a turning back value (ro, ru) of the friction spring element and the corrected position (zo+ro; zu−ru) of the clutch actuator is approached by the closed-loop controller. After reaching the corrected position (zo+ro; zu−ru) the closed-loop controller is switched off by dissipating the potential energy stored in the friction spring element.

Controlling a clutch by means of an actuator, wherein at least one first shaft can be torque-transmittingly connected to a second shaft by means of the clutch, the clutch in one of at least three states, where in an disengaged first state, a torque cannot be transmitted, in a second state, a torque can be transmitted such that the speeds of the first shaft and the second shaft are synchronized in the second state, and in an engaged third state, a required torque can be transmitted; wherein, in various states and in an operating mode associated with the particular state, the actuator is adjusted at a different speed in order to adjust the clutch.

A method sets a predefined position of a clutch actuator comprising a friction spring element. An activation path of the clutch actuator that actuates the clutch is predefined by a coupling torque via a coupling characteristic curve, wherein the predefined position (zo, zu) to be assumed by the clutch actuator is set by a closed-loop controller. To enable the predefined position of the clutch actuator to be set precisely without using additional energy, the predefined position (zo, zu) is corrected by a turning back value (ro, ru) of the friction spring element and the corrected position (zo+ro; zu−ru) of the clutch actuator is approached by the closed-loop controller. After reaching the corrected position (zo+ro; zu−ru) the closed-loop controller is switched off by dissipating the potential energy stored in the friction spring element.