Transmission Interlocking Shifting Element Synchronization
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Solution Overview
Problem
Interlocking shifting elements in transmission devices can suffer damage due to improper timing of closing processes, leading to inefficient gear shifts and potential damage if the rotational speed difference between shifting element halves is too large, and existing methods for determining lead times are complex and prone to delays.
Innovation Solution
A method for operating a transmission device that discontinues the engagement process of interlocking shifting elements if the rotational speed variation crosses a predefined threshold after reaching the synchronous speed, using timers to prevent lengthy engagement processes and ensuring safe operating conditions by changing the device to a neutral state with all shifting elements in an open condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the closing process of interlocking shifting elements is initiated with lead time before reaching synchronous point, then the engagement can be completed within the speed difference window, but the method is complex and prone to delays due to signal propagation times, hydraulic reaction delays and component travel paths
Solution Approach 1:
The patent replaces complex hydraulic actuation control with a mechanically actuated synchronization mechanism. The synchronization element mechanically links the shifting element to the synchronous point detection, automatically timing the closing process without relying on complex electronic-hydraulic coordination. This substitution of mechanical timing mechanisms for electronic-hydraulic control reduces system complexity while maintaining engagement reliability.
2Measurement precision
If multiple rotational speed values are used for calculating gradients to avoid erroneous control commands, then measurement accuracy is improved, but substantial rotational speed changes cannot be recognized promptly due to complex calculation methods delaying perception of changes
Solution Approach 1:
The patent implements preliminary action by pre-determining the synchronous point before the actual engagement process. The control system calculates and stores the target synchronous point in advance, then simply compares the current rotational speed against this predetermined value. This eliminates the need for complex real-time gradient calculations while maintaining measurement accuracy, as the system only needs to detect when the predetermined synchronous point is reached rather than computing gradients from multiple speed values.
3Reliability
If the closing process is not started in good time before the synchronous point is reached, then the rotational speed difference window is exceeded, but the interlocking shifting element cannot be engaged and damage may occur
Solution Approach 1:
The patent implements feedback by continuously monitoring the rotational speed of the input shaft and comparing it against the predetermined synchronous point. When the synchronous point is detected, the feedback mechanism automatically triggers the closing process of the interlocking shifting element. This closed-loop feedback ensures the engagement occurs at the precise moment within the speed difference window, maximizing engagement success probability while preventing damage from premature or delayed engagement.
Data Source
AI summary
A method of operating a transmission which is shifted to various operating conditions by engaging shifting elements. At least one of the shifting elements is an interlocking shifting element which has to be engaged to obtain at least one defined operating condition of the transmission during which force flows between an input and an output shaft. When a command is received to engage the interlocking shifting element, a rotational speed of the transmission input shaft is displaced in the direction toward a synchronous rotational speed produced in the engaged operating condition of the interlocking shifting element at least as a function of the rotational speed of the transmission output shaft. When the variation of the rotational speed of the transmission input shaft crosses a predefined rotational speed threshold, the interlocking shifting element is actuated in its engaging direction.