A method (200) for the open-loop control of a gearbox (100) that comprises an input shaft (105) and a first and a second proportionally controllable shift element (A-F) is provided. The method includes disengaging (215) the first shift element (A-F) according to a first control profile and engaging (220) the second shift element (A-F) according to a second control profile. The method also includes cyclically performing the following during the disengagement and the engagement: determining (230) a difference between the rotational speed of the input shaft (105) and a rotational speed which the input shaft (105) assumes when the second shift element (A-F) has been completely engaged; determining (230) a gradient of the difference; and adapting (230) the first control profile on the basis of the gradient.

A vehicle transmission system includes a shift cam rotated by rotary power from an output torque of a gearshift actuator motor to change a gearshift position and a rotational position holding mechanism configured to hold a rotational position of the shift cam. The rotational position holding mechanism has a rotatable member that is rotated in synchronization with the shift cam and has a plurality of indented portions along a rotational direction and a stopper member inserted into the indented portion of the rotatable member to hold a rotational position of the rotatable member. An unindented portion between the plurality of indented portions on the outer circumferential surface of the rotatable member is formed on a circular arc curved surface concentric on a rotation center line.

A control system and method for controlling a multiple gear ratio automatic transmission in a powertrain for an automatic transmission having pressure activated fiction torque elements to effect gear ratio upshifts. The friction torque elements are synchronously engaged and released during a torque phase of an upshift event as torque from a torque source is increased while allowing the off-going friction elements to slip, followed by an inertia phase during which torque from a torque source is modulated. A perceptible transmission output torque reduction during an upshift is avoided. Measured torque values are used during a torque phase of the upshift to correct an estimated oncoming friction element target torque so that transient torque disturbances at an oncoming clutch are avoided and torque transients at the output shaft are reduced.

A transmission includes at least one shift element for which both the apply pressure and the release pressure are actively controlled. A controller adjusts the torque capacity of the shift element by varying the apply pressure and the release pressure in a coordinated fashion. During particular events, such as a shift event with the shift element as oncoming element or holding element, both the apply pressure and the release pressure are monotonically increased, mitigating the effect of hysteresis,

An automatic transmission for a vehicle drivetrain includes a transmission housing, an input shaft, an output shaft, and a plurality of gears within the transmission housing. The plurality of gears defines multiple mechanical gear ratios between the input shaft and the output shaft. The transmission further includes a plurality of clutches operable to selectively engage the multiple mechanical gear ratios, and a plurality of rotational speed sensors. Each rotational speed sensor is operable to measure rotational speeds relative to the transmission housing for of one of the input shaft, the output shaft, or one of the plurality of gears. The transmission further includes a transmission control system configured to receive signals representing the measured rotational speeds from the plurality of rotational speed sensors and control the plurality of clutches to change between gear ratios based at least in part on the signals representing the measured rotational speeds.

A control system and method for controlling a multiple gear ratio automatic transmission in a powertrain for an automatic transmission having pressure activated friction torque elements to effect gear ratio upshifts. The friction torque elements are synchronously engaged and released during a torque phase of an upshift event as torque from a torque source is increased while allowing the off-going friction elements to slip, followed by an inertia phase during which torque from a torque source is modulated. A perceptible transmission output torque reduction during an upshift is avoided. Measured torque values are used during a torque phase of the upshift to correct an estimated oncoming friction element target torque so that transient torque disturbances at an oncoming clutch are avoided and torque transients at the output shaft are reduced.

A transmission includes a stationary member, an input member, and gear sets each having a plurality of nodes. The transmission includes a first clutch that connects a node of one gear set to the stationary member to establish an L1 mode, and a second clutch that connects a node of another gear set to the stationary member to establish a 2L mode. A SOWC is connected between nodes of two gear sets, and a controller, in response to a requested shift L1-L2 shift while engine braking, executes a method to release the first clutch and thereby enters a neutral mode. The SOWC is released when slip across the first clutch exceeds a first threshold, then the first clutch reapplied when a SOWC slip level exceeds another threshold to thereby enter a 1.sup.st gear freewheeling mode. The second clutch is reapplied to enter the L2 mode and resume engine braking.

A shift control system for vehicle that improves an acceleration feeling while suppressing a shift shock includes a controller that controls a transmission and a hydraulic controller. The controller, during an inertia phase where an input speed of the transmission changes toward a synchronous speed in a gear stage after a shift, sets an oil pressure of a specific frictional engagement device configuring the gear stage after the shift, of a plurality of frictional engagement devices to an oil pressure that, at a time of the shift, exceeds a first oil pressure to set a transmission torque capacity equal to a first drive torque applied to the specific frictional engagement device of a drive torque outputted from a prime mover, but is less than a second oil pressure to set a transmission torque capacity equal to a second drive torque which is the first drive torque to which has been added an inertia torque generated by inertia on a prime mover side accompanying a change in speed ratio.

A control device that controls a vehicle drive transmission device including a speed change device disposed on a power transmission path connecting an internal combustion engine and wheels, and an engagement device disposed between the internal combustion engine and the speed change device, the control device including an electronic control unit.

A method for controlling a transmission to reduce or suppress vibrations of transmission elements and/or rattling sounds, in particular in dual-clutch transmissions having a first transmission line with a first clutch and having a second transmission line with a second clutch. Transmission ratios are assigned to the transmission lines so that torque is transmissible between an input shaft and an output shaft of the transmission via a selected transmission line with a transmission ratio selected. The clutch of the selected transmission line is operated with slippage in predetermined operating situations to transmit torque.