A method for determining reference values of a sensor is provided. The reference values correspond to a disengaged operating condition or to an engaged operating condition of a form-locking shift element (A, F). With the aid of the sensor, at least one operating parameter of the shift element (A, F) determinable during a disengagement and during an engagement of the shift element (A, F). A torque, an actuation force of the shift element (A, F), and a differential speed between shift-element halves of the shift element (A, F) are varied during the determination of the reference values of the sensor in such that the form-locking shift element (A, F) is transferred into the disengaged operating condition or into the engaged operating condition.

Provided is a transmission which eliminates torque loss during gear shift and with which the processing of components can be simplified. An axial force is generated in a protrusion by means of a first portion during gear shift from a low gear to a high gear, and when a low-speed transmission gear and a clutch ring separate from each other, a high speed transmission gear and the clutch ring interlock. Since relative movement of the protrusion in a neutral direction is suppressed by means of a first retaining portion during coasting, gear disengagement whereby the transmission gears and the clutch ring separate from each other can be suppressed. Since the first retaining portion can be formed in a first wall when providing a groove portion, an increase in the component processing workload can be suppressed.

A shifting mechanism whose axial length is reduced without increasing a manufacturing cost. The shifting mechanism comprises: a cylindrical cam; a serpentine cam groove formed on the cam; a cam follower contacted to the guide section to be reciprocated in an axial direction; and a shift fork connected to the cam follower. The cam follower is pushed onto one of walls of a cam groove serving as a guide wall by a pushing member.

A method for monitoring a signal of a sensor is provided. With the aid of the sensor, a current actuating-travel position of at least one movable shift-element half of a form-locking shift element (A, F) of a transmission (3) is detected during a disengagement or an engagement of the shift element (A, F). A malfunction of the sensor is detected when the current actuating-travel position of the movable shift-element half is located outside the actuating-travel range defined by the end positions and is spaced apart from the first end position or from the second end position by an extent greater than a threshold value. Additionally, it is determined, during a subsequent actuation of the shift element (A, F), depending on rotational speeds of components of the transmission (3), whether the movable shift-element half is located in a demanded end position.

Torque reduction control is executed for temporarily reducing a torque capacity of a reaction engagement device during a transition of a shift. The reaction engagement device is maintained in an engaged state from before the shift to after the shift such that a predetermined rotating element in an automatic transmission bears a reaction caused by progress of the shift resulting from a change of an engaging-side engagement device into an engaged state. Therefore, without delaying a change of the engaging-side engagement device into the engaged state, transmission of torque that is generated as a result of rattling during a transition of a shift is reduced. Thus, in shift control over the automatic transmission, shock at the time of rattling is reduced while a stop of a shift due to a delay in change of the engaging-side engagement device into the engaged state is prevented.

A control apparatus for a vehicular transmission including at least one dog clutch each having a first dog member mounted on a first shaft such that the first dog member is rotated together with the first shaft, and at least one second dog member each mounted to be axially adjacent to the first dog member and rotatable relative to the first shaft, first gears each mounted to be rotatable relative to the first shaft and provided with the second dog member, second gear which are mounted such that the second gears are rotated together with a second shaft parallel to the first shaft, and which mesh with the respective first gears, and a shifting mechanism for selectively placing each dog clutch in an engaged or released state. The control apparatus includes: a first calculating portion for detecting to a rotary angular position of the first shaft, and calculating a rotary angular position of the first dog member on the basis of the detected rotary angular position of the first shaft; a second calculating portion for detecting a rotary angular position of the second shaft, and calculating a rotary angular position of each second dog member on the basis of the detected rotary angular position of the second shaft; and an engagement control portion for controlling the shifting mechanism on the basis of the rotary angular positions of the first and second dog members, for engagement of the first and second dog members with each other.

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.

In a control device of a vehicle including a first power transmission path transmitting a power through a belt-type continuously variable transmission and a second power transmission path transmitting a power through a reduction gear mechanism in parallel between an input shaft and an output shaft and including a dog clutch in series with the reduction gear mechanism in the second power transmission path, when the dog clutch is in an engagement transition state and a rotational speed change of the output shaft is equal to or greater than a predetermined value, the engagement transition state of the dog clutch is canceled to release the dog clutch.

Methods and system are described for changing a gear ratio of an axle gearbox that does not include friction clutches and that may or may not include synchronizers. The axle gearbox may receive propulsive force via an electric machine. The methods and systems permit the axle gearbox to be shifted from a high gear range to a low gear range while a vehicle that includes the axle gearbox is moving.

Methods and systems are provided for controlling engine operation in response to a request to shift a transmission gear. In one example, a method may include maintaining operating conditions of an engine and redirecting electric power generated via the engine from a traction motor to a battery in response to a request to shift a transmission while the driveline is operating in a series mode. In this way engine efficiency may be improved and a time frame for shifting a transmission gear may be reduced responsive to a gear shift request while the powertrain is operating in series mode.