METHOD FOR CONTROLLING SHIFTS IN AN AUTOMATED STEP-DOWN TRANSMISSION
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Abstract
A method of controlling an automated step-down transmission, arranged in a drivetrain between an engine and a drive axle, which includes a multi-stage main transmission and a range group. The main transmission has an intermediate transmission style with a countershaft having a transmission brake and an input shaft connected, via a clutch, to the engine. The main transmission shifts, without being synchronized, and the range group shifts, after synchronization, such that the engaged gear ratio of the main transmission remains engaged during a range shift operation. The range shift is accomplished by firstly reducing drive engine torque; secondly, disengaging the existing gear ratio of the range group; thirdly, remotely synchronizing the target gear ratio in the range group; fourthly, engaging the target gear ratio in the range group; and fifthly, increasing the drive engine torque.
30 Citations
34 Claims
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1-17. -17. (canceled)
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18. A method for controlling an automated step-down transmission (CT), the automated step-down transmission (CT) being arranged in a drivetrain of a motor vehicle, between either a drive engine or a hybrid drive and an drive axle, and comprising at least a multi-stage main transmission (HG) and a range group (GP) connected downstream from the main transmission (HG), the main transmission (HG) has an intermediate transmission configuration and at least one countershaft (WVG1) that is engaged by a transmission brake (Br), an input shaft (WGE) being connected, via a controllable separator clutch (K), to the drive engine or the hybrid drive, the main transmission (HG) being shiftable without synchronization and the range group (GP) being shifted, after synchronization, such that during a range shift, a transmission ratio step (R) that is engaged in the main transmission (HG), before the range shift, remains engaged after the range shift, the method of controlling the step-down transmission (CT) during the range shift comprising the steps of:
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reducing a load, which is transmitted by the step-down transmission (CT), by reducing torque that is output by the drive engine or the hybrid drive; disengaging a current ratio step (L;
S) that is engaged in the range group (GP=N) before the range shift was initiated;synchronizing a target ratio step (S;
L) in the range group (GP) that is the objective of the range shift;engaging the target ratio step (S;
L) in the range group (GP); andincreasing the load, which is transmitted by the step-down transmission (CT), by increasing the torque that is output by the drive engine or the hybrid drive. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 32)
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26. A method of controlling an automated step-down transmission (CT), in which the automated step-down transmission (CT) is arranged in a drivetrain of a motor vehicle between either a drive engine or a hybrid drive and an drive axle, comprises at least a multi-stage main transmission (HG) and a range group (GP), which is connected downstream from the main transmission (HG), the main transmission (HG) having an intermediate transmission configuration and at least one countershaft (WVG1) that is engaged by a transmission brake (Br), an input shaft (WGE) being connected, via a controllable separator clutch (K), to the drive engine or the hybrid drive, the main transmission (HG) being shiftable without synchronization and the range group (GP) being shifted after synchronization such that during a range shift a transmission ratio step (R) that is engaged in the main transmission (HG), before the range shift, remains engaged after the range shift, the method of controlling the step-down transmission (CT) during the range shift comprises the steps of:
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reducing a load, which is transmitted by the step-down transmission (CT), by reducing torque that is output by the drive engine or the hybrid drive; disengaging a current ratio step (L;
S) that is engaged in the range group (GP=N) before the range shift was initiated;remotely synchronizing a target ratio step (S;
L) in the range group (GP) that is the objective of the range shift by an specifying an offset value for a target speed of the target ratio step (S;
L), by which the target speed is corrected;engaging the target ratio step (S;
L) in the range group (GP); andincreasing the load, which is transmitted by the step-down transmission (CT), by increasing the torque that is output by the drive engine or the hybrid drive. - View Dependent Claims (27, 28, 29, 30, 31, 33, 34)
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Specification