Automated Group Gear Shift Control via Parallel Synchronization
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Solution Overview
Problem
Automated group transmissions with synchronized sub-transmissions experience long shifting times during gear changes, particularly during range shifts, which can be annoying for drivers and impair vehicle dynamics.
Innovation Solution
Implementing a method for shift control that synchronizes the main transmission and range group in parallel using external synchronization aids, allowing overlapping shifting processes and eliminating the need for a neutral position in the range group, thereby reducing overall shifting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential shifting is used in synchronized sub-transmissions, then shifting reliability is maintained, but shifting time becomes excessively long
Solution Approach 1:
The input shaft of the main transmission is synchronized to the target speed using external synchronization aids (engine and separating clutch) before the actual gear engagement. This preliminary speed matching allows the subsequent gear shifting to occur without speed differential, enabling parallel execution of synchronization and gear ratio changes in the range group, thereby reducing total shifting time while maintaining reliability
Solution Approach 2:
The shifting process is made continuous by eliminating the neutral position requirement in the range group. The gear ratio change occurs without interruption or disconnection, allowing the shifting operation to proceed without stopping the power flow or requiring intermediate idle states, thus significantly reducing shifting time
2Reliability
If neutral position is required for range group switching, then shifting safety is ensured, but shifting complexity increases
Solution Approach 1:
The neutral position requirement is extracted and removed from the range group switching process. The invention enables direct gear ratio changes without requiring the range group to pass through a neutral state, simplifying the shifting sequence and reducing the number of switching steps while safety is maintained through external synchronization control
Solution Approach 2:
Speed synchronization is performed in advance on the input shaft using external aids before the range group gear change. This preliminary action ensures that when the gear is engaged, speeds are already matched, eliminating the need for neutral position as an intermediate safety state and directly reducing shifting complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly shortens shifting times, enhances shifting comfort, and reduces wear on transmission components by allowing simultaneous synchronization of transmission groups, ensuring faster and more efficient gear changes without fully disconnecting the drive train.
Implementation Method 1
the synchronizing devices for the main transmission each having two shift positions for the relevant gear ratio steps and one shift position for a neutral position
Implementation Method 2
The rotating free masses of the main transmission and the splitter group are then slowed down by a transmission brake to a switchable low speed that is permissible for disengagement
Data Source
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AI summary
The invention relates to a method for shift control of an automated group gear, wherein the group gear has at least one multi-speed main gear (HG) and an at least two-speed range group (GP) which is arranged downstream of the main gear (HG) in drive terms and is drive-connected to the latter by means of a main shaft (5), and with which an input shaft (4) of the main gear (HG) can be drive-connected or is drive-connected to a drive device (1) and with which the main gear (HG) and the range group (GP) have synchronisation devices (SP1, SP2, SP3, SP4) with shifting clutches, wherein the synchronisation devices (SP1, SP2, SP3) for the main gear (HG) each have two shift positions for the relevant gear speed and one shift position for a neutral position, wherein the at least one synchronisation device (SP4) of the range group (GP) has only two shift positions for the relevant gear speeds, and with which a change between two gear speeds takes place in each case in the main gear (HG) and in the range group (GP) during a range shift. In order to achieve short shift times, the input shaft (4) of the main gear (HG), which has previously been shifted to neutral by controlling external synchronisation aids (1, 3) which act on the input shaft (4), is synchronised to a target rotation speed (n_Ziel) during synchronisation of the range group (GP) on range shifting, and once the target rotation speed has been reached, either after synchronisation and shifting of the gear speed of the range group (GP) or independently of the instantaneous synchronisation state of the range group (GP), the new transmission stage is engaged in the main gear (HG).