A method for operating an automatic transmission is provided. The method includes initiating a synchronization of a positive shifting element of the automatic transmission. The method also includes closing a first non-positive shifting element of the automatic transmission and positioning a second non-positive shifting element of the automatic transmission at an engaged configuration of the second non-positive shifting element during the synchronization of the first positive shifting element in order to synchronize the first positive shifting element.

A method for operating an automatic transmission is provided. The method includes initiating a synchronization of a positive shifting element of the automatic transmission while the automatic transmission is operating at less than a threshold output speed. The method also includes closing a first non-positive shifting element of the automatic transmission and positioning a second non-positive shifting element of the automatic transmission at an engaged configuration of the second non-positive shifting element during the synchronization of the first positive shifting element in order to synchronize the first positive shifting element.

A method for operating an automatic transmission includes determining at least one of an elapsed time from adjusting a first one of at least one positive-locking shift element towards a closed configuration or a differential speed rotation of the first one of the at least one positive-locking shift element and shifting the automatic transmission to a substitute gear if the elapsed time from adjusting the first one of the at least one positive-locking shift element towards the closed configuration reaches or exceeds a time limit and/or the differential speed rotation of the first one of the at least one positive-locking shift element reaches or exceeds a rotational speed limit. A related transmission control device for an automatic transmission is also provided.

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.

The invention provides an engagement method for engaging a first gear element with a second gear element, at least the second gear element being mounted to move between a meshing position and a disengaged position by means of an actuator. The engagement method including a step of driving at least one of the gear elements in rotation so as to establish a non-zero difference in speed of rotation between said gear elements, and a step of controlling the actuator to perform the following in succession: moving at least the second gear element towards the meshing position; on detecting contact between the gear elements, stopping the movement of the second gear element; and on detecting an ideal angular position for engaging said gear elements, moving the second gear element as quickly as possible into the meshing position.

This application provides a two-speed transmission system. The two-speed transmission system includes a first fixed gear fastened on a first shaft, a first floating gear connected to a second shaft through rotation, a first connection mechanism, and a one-way clutch. The first connection mechanism is configured to implement connection or disconnection between the first floating gear and the second shaft. The one-way clutch is located between the first floating gear and the first connection mechanism. An inner surface of the one-way clutch is connected to the first floating gear. An outer surface of the one-way clutch abuts against the first connection mechanism. The outer surface of the one-way clutch is connected to the first connection mechanism. An acting force of the outer surface directly acts on the first connection mechanism instead of a tooth surface of the first floating gear, to reduce an impact on accuracy of gear transmission.

A variable speed control system includes a multiple-speed transmission which changes a speed of an engine output in multiple stages based on a change in meshing state of a dog clutch which is caused in association with an operation of a change pedal connected mechanically, a pedal load detection device which detects an operation load of the change pedal, and a control unit which suppresses or shuts off an engine output to the multiple-speed transmission and permits a speed change action of the multiple-speed transmission by the change pedal when a detected pedal load exceeds a pedal load threshold. The variable speed control system further includes an engine revolution speed detection sensor which detects an engine revolution speed. The control unit changes the pedal load threshold according to the engine revolution speed detected. Such variable speed control system can realize a stable speed change action irrespective of running conditions.

A transmission system for a vehicle has a shift driving mechanism which operates, under control by a control unit, at the time of shifting the gear position, to disengage a transmission gear of a current gear position and a shifter from each other after engaging a transmission gear of a next gear position and a shifter with each other in a condition where a transmission clutch that transmits power to the transmission gear of the next gear position is in an engaged state. This ensures smoother and swifter shifting of gear position.

The present invention relates to a two-speed transmission for an electric driving vehicle and the two-speed transmission for an electric vehicle has only one actuator. The transmission comprises a planetary gear mechanism (12), an elastic body (44), an armature (26) to integrally rotate with an input axis, an electromagnetic coil (46) and a multi-plate friction clutch (30). A ring gear (20) is fixed to a housing. The armature (26) comprises clutch projection portions (26-1). A dog clutch is constituted by the clutch projection portions (26-1) and recess portions (18-2) of a sun gear (18). When the electromagnetic coil (46) is not electrically energized, the dog clutch is engaged. The rotation of the input axis is reduced and is transmitted to an output axis via the sun gear (18) and a carrier (16). When the electromagnetic coil (46) is electrically energized, the armature (26) is displaced against elastic force, the dog clutch becomes a non-engaging state, a multi-plate friction clutch (30) becomes an engaging state by pressing flange portions (26-4) of the armature (26) and the rotation of the input axis is transmitted to the output axis with a one-to-one relationship. The transmission can comprise a one-way clutch to prevent torque interruption when switching the gear ratio.

A control device and a method for controlling a vehicle powertrain to overcome, or avoid, a cog-to-cog condition during gear shifting is provided. The method comprises, when an input shaft of the gearbox is rotating, controlling a synchromesh arrangement so as to induce a difference in rotational speed between a first gear wheel and a first coupling sleeve arranged to lock the first gear wheel to a main shaft of the gearbox by at least partly engaging the first gear wheel or a second gear wheel to the input shaft. Furthermore, a computer program, a computer-readable medium and a vehicle are provided.