At the time when a hydraulic actuator is operated to engage a dog clutch, after it is detected that a hydraulic pressure for operating the hydraulic actuator is higher than or equal to a predetermined hydraulic pressure, it is determined whether the dog clutch is not engaged. Therefore, non-engagement determination due to insufficient hydraulic pressure for operating the hydraulic actuator is prevented. Thus, at the time when the hydraulic actuator is operated to engage the dog clutch, it is possible to prevent consumption of time to engage the dog clutch due to unnecessary re-engagement operation.

A control device that controls an automatic transmission is provided, in which device the automatic transmission includes a variator disposed in a power transmission path between a driving source and a driving wheel of a vehicle, and a friction engaging element disposed between the variator and the driving wheel, in a manner capable of transmitting a power disconnectably via the power transmission path. The control device increases a speed ratio of the variator toward a predetermined target speed ratio with disengaging the friction engaging element during a vehicle stop of the vehicle, and executes a learning regarding a hydraulic control of the friction engaging element when the friction engaging element is disengaged during the vehicle stop. The control device decreases the target speed ratio at a time of learning when the learning is executed during the vehicle stop, compared to a time of vehicle stop other than the time of learning.

A control device of a vehicle power transmission device including a first power transmission path transmitting power by engaging a first clutch, a sub-clutch and a second power transmission path transmitting power by engaging a second clutch each disposed between an engine and drive wheels and parallel to each other, the device including a fail-safe valve for preventing simultaneous engagement of the first and second clutches, the fail-safe valve configured to be switched to a fail-safe spool position preventing simultaneous engagement of the first and second clutches by a hydraulic pressure of a hydraulic fluid supplied to the first clutch or an output pressure of a first electromagnetic valve controlling the hydraulic pressure and the hydraulic pressure of the hydraulic fluid supplied to the second clutch or an output pressure of a second electromagnetic valve controlling the hydraulic pressure, the second electromagnetic valve configured to increase the output pressure.

A vehicle includes a continuously variable transmission, a gear mechanism and a controller. The continuously variable transmission and the gear mechanism are provided in parallel with each other between an input shaft and an output shaft. The controller is configured to i) when the vehicle travels in a state where both a first clutch and a third clutch provided on the gear mechanism side are released, gradually increase a hydraulic pressure of the first clutch such that the first clutch is engaged, ii) calculate a command hydraulic pressure for setting the first clutch to a pressure regulating state on the basis of a command hydraulic pressure of the first clutch at a timing at which the amount of change in an output-side rotation speed of the first clutch becomes larger than a predetermined value, and iii) control the first clutch by using the calculated command hydraulic pressure.

A continuously variable transmission, a control system, and a method are provided. The control system and method are configured to learn a desired running pressure to be applied to a clutch that is lower than a pulley clamping pressure and higher than a pressure at which the clutch would slip (a clutch critical pressure), so that the clutch can act as a fuse to avoid pulley slip. A plurality of clutch slip tests are performed, each of which include decreasing pressure supplied to the clutch until a clutch slip occurs. Clutch slip data points are collected at the point of slip and used to determine a gain and an offset, where the gain is a clutch pressure versus clutch torque capacity gain, and the offset is a clutch pressure offset, which is used to determine the clutch critical pressure.

A starting clutch control device for an automatic transmission has a starting clutch controller. The starting control device controls a transmission torque capacity of a starting clutch interposed in a transmission path in which rotation of the power source is transmitted to wheels while shifting is underway by the automatic transmission. The starting clutch controller controls the transmission torque capacity of the starting clutch such that a rotation trajectory of the power source develops as desired in a low rotation speed range in which the transmission torque capacity control of the starting clutch is necessary. The starting clutch controller causes the transmission torque capacity of the starting clutch to change, when a shift of the automatic transmission occurs during the transmission torque capacity control by the starting clutch controller, in a direction in which the change in the rotation trajectory will occur corresponding to the shift.

A vehicle clutch hydraulic system for a vehicle is provided with a mechanical oil pump, an electric oil pump, a forward clutch and a control valve unit. In the vehicle clutch hydraulic system, a main pump oil passage fluidly connects the mechanical oil pump to the control valve unit. A sub-pump oil passage fluidly connects the electric oil pump to a forward clutch oil passage into which an oil passage outlet opens at an inside location closer to a clutch rotational axis than a clutch oil chamber of the forward clutch.

In engaging (connecting) a dog clutch by operating a synchromesh mechanism, when there occurs an uplock at the time when a first pressing force is caused to act on a hub sleeve, tooth tips of spline teeth of the hub sleeve contact with tooth tips of spline teeth of a synchronizer ring, and these spline teeth cannot be engaged. However, when a second pressing force is caused to act on the hub sleeve, the uplock is easy to be released. In addition, when torque from an engine is caused to act on the hub sleeve, a displacement is caused to occur in a rotation direction between the mutually contacting spline teeth. Thus, the uplock is reliably released.

A method of calibrating a hydraulically operated clutch in a continuously variable transmission of a vehicle, includes steps of filling the clutch as if for a shift, using a control signal value for achieving a test pressure, and determining a resulting change in a pressure condition in a hydrostatic power unit of the transmission. If the change indicates initial engagement, then a value representative of the signal value used is recorded. If greater than initial engagement is indicated, or the vehicle moved, then the clutch is emptied and tested using a lower test pressure. If initial engagement is not indicated, the clutch is emptied and refilled to a greater test pressure. An exemplary pressure condition is a difference in pressure in lines between a pump and motor of the power unit. During the calibration, the vehicle can be held stationary with a parking brake or the like.

A vehicle includes a continuously variable transmission, a gear mechanism and a controller. The continuously variable transmission and the gear mechanism are provided in parallel with each other between an input shaft and an output shaft. The controller is configured to i) when the vehicle travels in a state where both a first clutch and a third clutch provided on the gear mechanism side are released, gradually increase a hydraulic pressure of the first clutch such that the first clutch is engaged, ii) calculate a command hydraulic pressure for setting the first clutch to a pressure regulating state on the basis of a command hydraulic pressure of the first clutch at a timing at which the amount of change in an output-side rotation speed of the first clutch becomes larger than a predetermined value, and iii) control the first clutch by using the calculated command hydraulic pressure.