Wabco Gmbh & Co Ohg

Other

Gerhard B&ouml;ckmann

Andreas B&ouml;hm

Jon M Huber

A method for controlling a transmission of an engine-driven vehicle having a plurality of gears, the vehicle including a service module actuable by a driver of the vehicle to select a desired gear, the service module being connected to a transmission control system which automatically changes gears in response to actuation of the service module, the vehicle further including an engine braking system connected to the transmission control system which is actuable to brake the vehicle engine during a gear change, the method comprising: monitoring the transmission input rotational speed (N ) and the transmission output rotational speed (N ); calculating a synchronous rotational speed (N ) of the desired gear; actuating the engine braking system to reduce the rotational input speed (N ) and synchronize it with the synchronous rotational speed (N ) so that the desired gear change can be effected; and disabling the engine braking system when a predetermined switch-off threshold is reached at a point in time before an expected synchronization of the rotational speeds (N ) and (N ) occurs. In one preferred embodiment, the engine braking system is disabled when the difference (D ) between rotational speeds (N ) and (N ) becomes equal to or less than a predetermined rotational differential value (D ). In another preferred embodiment, the engine braking system is disabled at a point in time which precedes the expected time of synchronization by fixed delay time (T ) which is typical for the engine braking system. By disabling the engine braking system before synchronization of the rotational speeds (N ) and (N ) actually occurs, the method accounts for hysteresis effects and the process of changing gears is speeded up.

Method for the control of a transmission

A method for controlling a transmission in a motor vehicle by operation of a transmission control system which evaluates the actuating wishes of the driver and by an electrical/pneumatic adjusting device, permits rapid shifting of gears in a non-synchronized transmission. In certain cases, for example when traveling uphill, the speed of the vehicle may decrease by the end of the gear changing process to such an extent that an engagement of the gear selected by the driver would lead to a drop below the engine idling speed. Similarly, the corollary applies to the highest acceptable engine speed, for example during down-hill travel. Therefore, the evolution in time of the actual transmission input speed or of the engine speed during a gear changing process is compared with the transmission input speed calculated on the basis of the gear ratio of the selected gear and the speed to be expected in case of synchronization of both speeds is calculated in advance. If the engine speed calculated in advance does not fall within the acceptable engine speed, another gear resulting in a rotational speed within the acceptable engine speed range is selected automatically.

Method of controlling a transmission

A shift by wire vehicle transmission system includes control methods that are especially useful for controlling the transmission under start-from-stop conditions. Since the master clutch must be manually operated under such conditions, the invention includes a method of determining whether the clutch is open or closed. The rotational speed of the engine output shaft is compared to the rotational speed of the transmission input shaft and if the difference between those speeds is greater than a preselected value, the clutch is determined to be open. Another use of the disclosed method is to provide an indication to the driver whether a desired gear has been engaged. A visual or audible signal indicates to the driver that the desired gear is not yet engaged. Once engagement is confirmed, the signal is turned off and the driver knows that the desired shift has been accomplished.

Growing community of inventors

Laatzen, Germany

Gerhard Böckmann

Growing community of inventors

Laatzen, Germany

Gerhard B&ouml;ckmann

Gerhard Böckmann