Transmission Shifting Element Load Transfer for Drag Reduction
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Solution Overview
Problem
Transmission devices with both frictional and positive-locking shifting elements face challenges in achieving smooth shifts without traction interruption and high comfort due to high drag torques, especially during downshifts, requiring innovative operational methods to manage shifting elements effectively.
Innovation Solution
A method for operating a transmission device with four planetary gear sets and six shifting elements, where two positive-locking shifting elements are used, involving the transfer of one positive-locking shifting element to a load-free state by increasing the transmission capacity of frictional-locking shifting elements, allowing shifts to be performed with low shifting forces and comfort, and reducing drag torques by varying the transmission capacity based on operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If positive-locking shifting elements are used to reduce drag losses, then energy efficiency is improved, but shifting time increases and shifting comfort deteriorates due to high drag torques
Solution Approach 1:
The patent applies preliminary action by pre-transferring the positive-locking shifting element to a load-free state before the actual shifting operation. This is achieved by temporarily increasing the transmission capacity of frictional-locking shifting elements to take over the load, allowing the positive-locking element to be released from its closed state without bearing high torques, thus enabling faster and more comfortable shifting while maintaining energy efficiency
2Loss of energy
If positive-locking shifting elements are used to reduce drag losses, then energy efficiency is improved, but shifting comfort deteriorates due to high mechanical loads
Solution Approach 1:
The patent applies preliminary action by pre-transferring the positive-locking shifting element to a load-free state before the actual shifting operation. This is achieved by temporarily increasing the transmission capacity of frictional-locking shifting elements to take over the load, allowing the positive-locking element to be released from its closed state without bearing high torques, thus enabling faster and more comfortable shifting while maintaining energy efficiency
3Ease of operation
If transmission capacity of frictional shifting elements is increased to transfer load, then positive-locking element can be opened, but frictional element must then be switched off requiring coordination
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the transmission capacity of frictional-locking shifting elements during the shifting process. The control system continuously monitors the shifting state and adjusts the transmission capacity in real-time, increasing it when needed to transfer load and decrease it when the positive-locking element is successfully opened, enabling automatic coordination without increasing mechanical complexity
Solution Approach 2:
The patent applies feedback by implementing a control system that monitors the transmission state and adjusts the transmission capacity of frictional shifting elements accordingly. The control device receives information about the current operating state and the state of shifting elements, and automatically adjusts the transmission capacity to ensure smooth load transfer and proper sequencing of shifting operations
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
Enables shifts with high comfort and low mechanical loads, ensuring shifts are carried out safely and without traction interruption within predefined times, even in unfavorable conditions, by effectively managing the transition of positive-locking shifting elements and frictional shifting elements.
Implementation Method 1
at least one or more of the frictional shifting elements are switched off from the power flow of a transmission device... During the engagement process of a frictional shifting element, no special synchronization measures are required to ensure the desired shifting comfort and shifting without any interruption in traction, since the desired shifting comfort and also shifting without any interruption in traction can be achieved by means of frictional shifting elements at defined contact pressures within a wide differential speed range
Implementation Method 2
at least one positive-locking shifting element must be switched on in a power flow of the transmission device in order to implement a defined shifting requirement
Data Source
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AI summary
The invention relates to a method for operating a transmission device (3) having a plurality of friction-fit shift elements (B, C, D and E) and at least one form-fit shift element (A, F) for describing different gear ratios. The form-fit shift element (A) is at least approximately transferred to a load-free state upon a requested change in operating state of the transmission device (3), during which the form-fit shift element (A) is transferred from a closed to an opened operating state, by raising the transferability of at least one friction-fit shift element (E), which is switched neither to describe the current operating state nor to describe the requested operating state in the flow of force of the transmission device (3).