Automatic Gearbox Shift Element Control for Safe Neutral Engagement
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Solution Overview
Problem
Current automatic transmissions lack methods for safe and gentle gear engagement, particularly when shifting from neutral to forward or reverse gears, as existing methods do not ensure secure and timely torque or force transfer.
Innovation Solution
A method for operating automatic transmissions that engages at least one shift element in a controlled manner during gear shifts, with specific procedures depending on the neutral position conditions, including engaging shift elements in a controlled manner to ensure safe and efficient torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple shift elements are engaged simultaneously in a gear engagement from neutral position, then the torque transfer can be established quickly, but the gear engagement becomes unsafe and abrupt
Solution Approach 1:
The gear engagement process is segmented into multiple sequential phases: first engaging shift elements that do not yet transfer torque (pre-engagement phase), then subsequently engaging the remaining shift elements that establish torque transfer (torque engagement phase). This segmentation allows the system to achieve both quick response and safe engagement by separating the timing of different shift element engagements.
Solution Approach 2:
The method performs preliminary engagement of certain shift elements before torque transfer is required. Specifically, shift elements are engaged in advance during a pre-engagement phase, preparing the transmission for torque transfer while maintaining safety. This preliminary action ensures that when torque transfer begins, the engagement is already partially established, reducing the overall engagement time while maintaining safety.
2Loss of time
If all shift elements are engaged at once during gear engagement, then the reaction time is reduced, but the torque transfer becomes abrupt and potentially harmful
Solution Approach 1:
The engagement sequence is divided into distinct temporal segments: a first phase where initial shift elements are engaged without torque transfer, and a second phase where remaining shift elements are engaged to establish torque transfer. This time-based segmentation eliminates abrupt torque transfer while maintaining minimal reaction time, as the system is already partially engaged when torque transfer begins.
Solution Approach 2:
The method applies beforehand cushioning by engaging certain shift elements in advance during a pre-engagement phase, before torque transfer is initiated. This creates a cushioning effect where the transmission is gradually prepared for torque transfer, preventing abrupt force application. The preliminary engagement of shift elements acts as a buffer that smooths the transition into full torque transfer.
3Reliability
If shift elements are engaged in a controlled sequence, then safe and gentle gear engagement is achieved, but the control complexity increases
Solution Approach 1:
The control system dynamically adjusts the engagement sequence based on real-time transmission state. The method monitors which shift elements are engaged and automatically executes the appropriate engagement sequence, making the control system adaptive rather than static. This dynamic approach manages complexity by using state-based logic that automatically determines the correct engagement path without requiring complex external control.
Solution Approach 2:
The transmission control system performs self-service by automatically managing the engagement sequence based on its own state. The system monitors its own shift element status and executes the appropriate engagement protocol without external intervention, reducing the burden on external control systems. This self-management capability simplifies overall control complexity while maintaining safe engagement procedures.
Data Source
AI summary
A method for operating an automatic transmission of a motor vehicle, in particular a variable-speed transmission. The automatic transmission includes at least five shift elements and to transfer torque or force transfer in a forward gear and a reverse gear at least three shift of the at least five elements are engaged. When shifting the automatic transmission from a neutral position to a forward or a reverse gear, at least one of the three shift elements of the automatic transmission that are engaged in the respective forward or reverse gear, is engaged in a controlled manner.