Automated Transmission Shift Control Using Active Synchronization
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Solution Overview
Problem
Existing methods for shift control in automated group transmissions with unsynchronized range groups are inefficient, particularly when there is no upstream splitter group, as they require deceleration of the drive motor to reach synchronous speed before engaging the target gear ratio, slowing down the shifting process.
Innovation Solution
A method that involves load reduction of the drive motor, disengagement of the separating clutch, synchronization of the target gear ratio using a transmission brake, and sequential engagement of the target gear ratios in both the range and main transmissions, allowing for faster and more convenient range upshifts and downshifts, applicable to transmissions with or without an upstream group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive motor is decelerated to reach synchronous speed before engaging the target gear ratio, then the gear engagement is smooth and reliable, but the shifting time is prolonged and shifting speed is reduced
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the speed of the input shaft and the target gear ratio components using a synchronization device before the actual gear engagement. This allows the dog clutch to engage without requiring deceleration of the drive motor, thus maintaining shifting speed while ensuring reliable engagement. The synchronization is achieved in advance through the synchronization mechanism that equalizes the speeds of the moving and stationary parts before clutch engagement.
Solution Approach 2:
The patent segments the shifting process into two independent parts: speed synchronization (handled by the synchronization device) and gear engagement (handled by the dog clutch). This segmentation allows the drive motor to maintain its speed while the synchronization device independently equalizes the speeds of the gear components, eliminating the need to decelerate the motor for synchronization and thus reducing shifting time.
2Ease of operation
If synchronized clutches are used in the range group, then the shifting process is simplified and can be performed automatically, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces a synchronization device as an intermediary mechanism that enables the use of simpler unsynchronized dog clutches. The synchronization device acts as a mediator that equalizes the speeds of the gear components before engagement, allowing the dog clutch to engage smoothly without requiring the complex synchronized clutch structure. This intermediary device maintains ease of automatic shifting operation while reducing overall device complexity.
Solution Approach 2:
The patent replaces the complex synchronized clutch mechanical system with a combination of a simple synchronization device and an unsynchronized dog clutch. The synchronization device uses a different mechanical approach (friction-based speed equalization) to achieve the same functional result as synchronized clutches, but with simpler engagement mechanics that allow for more straightforward automatic control.
3Duration of action of stationary object
If the range group is synchronized, then the service life of the transmission is extended, but the space requirement and manufacturing cost increase
Solution Approach 1:
The synchronization device acts as an intermediary that protects the unsynchronized dog clutch from excessive wear by ensuring smooth engagement. This allows the use of simpler, more compact unsynchronized clutch structures that would otherwise have short service lives, thereby extending transmission service life without requiring the larger space needed for fully synchronized clutch packages.
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 method significantly shortens the shifting time and enhances shifting comfort by actively synchronizing dog-shifted sub-transmissions using controllable elements, enabling faster range shifts with improved efficiency and convenience.
Implementation Method 1
the countershaft and/or the main shaft connected to it via the still engaged actual transmission stage of the main transmission are braked by a corresponding actuation of the transmission brake
Implementation Method 2
the input shaft is connected to the drive motor via a controllable separating clutch
Data Source
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AI summary
The invention relates to a method for the shift control of an automated range transmission, which is arranged in a drive train of a motor vehicle between a drive motor and an axle drive and comprises at least one multi-stage main transmission (HG, HG') and a downstream two-stage range group (GP), wherein the main transmission (HG, HG') is designed as a reduction gear with at least one countershaft (WVG1, WVG) equipped with a controllable transmission brake (Br), the input shaft (WGE) is connected to the drive motor via a controllable disconnect clutch (K), and the main transmission (HG, HG') and the range group (GP) are each switchable via unsynchronized dog clutches grouped in pairs in a common shift package (S1, S2, S1' - S3', SP) with two shift positions and a neutral position (N), wherein during range shifting both in the main transmission (HG,In both the HG' and the range group (GP), a change between two gear ratios takes place. To achieve a short overall shift time and high shift comfort, a procedure is proposed for range upshifting and range downshifting, which includes active synchronization of the dog-clutch-shifted sub-transmissions (HG, HG', GP) using the transmission brake (Br) and the disconnect clutch (K).