Multi-Speed Transmission Neutral Control for Cold Drag Losses
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Solution Overview
Problem
Multi-gear vehicle transmissions face challenges in accurately determining the pre-filling of pressure medium for shifting elements, leading to undesired rolling or delayed gear engagement due to insufficient or excessive pre-filling, especially in conditions with elevated drag losses where the transmission is cold.
Innovation Solution
A method that involves determining the transmission condition with elevated drag losses and additional closure of shifting elements beyond those associated with the driving gear to prevent undesired rolling, using sensor information and temperature thresholds to manage gear shifts and ensure quick, comfortable transitions between neutral and driving gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the shifting element is pre-filled with pressure medium in neutral gear, then the gearshift into driving gear becomes faster, but the vehicle may experience undesired rolling due to excessive pre-filling
Solution Approach 1:
The patent applies preliminary action by pre-filling the shifting element with pressure medium before the actual gearshift is required. This preparation reduces the response time when shifting from neutral to driving gear, as the pressure medium is already positioned to enable rapid closure of the shifting element. The control unit monitors transmission conditions and adjusts the pre-filling amount dynamically to prevent excessive pre-filling that could cause undesired rolling.
Solution Approach 2:
The patent implements feedback by continuously monitoring transmission conditions including temperature, drag losses, and shifting element state. The control unit uses this feedback information to dynamically adjust the amount of pressure medium delivered to the shifting element during pre-filling. This closed-loop control ensures optimal pre-filling amounts under varying operating conditions, preventing both insufficient pre-filling (delayed gearshift) and excessive pre-filling (undesired rolling).
2Reliability
If the shifting element is pre-filled with insufficient pressure medium, then undesired rolling is avoided, but the gearshift becomes delayed and uncomfortable
Solution Approach 1:
The control unit performs preliminary action by delivering a calculated amount of pressure medium to the shifting element while in neutral gear. This pre-filling preparation ensures that when the driver requests a gearshift, the shifting element is already close to its closing position, significantly reducing the actual shift time and improving shift comfort. The amount is dynamically adjusted based on real-time transmission conditions.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the pre-filling amount of pressure medium based on transmission temperature and drag loss conditions. When the transmission is cold with elevated drag losses, the control unit reduces or eliminates pre-filling to prevent rolling. When the transmission is warm with normal drag losses, the control unit increases pre-filling to minimize gearshift time and improve comfort. This adaptive parameter adjustment optimizes both stability and responsiveness.
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 effectively prevents undesired rolling by bracing the vehicle transmission, allowing for quicker and more comfortable gear shifts, and helps the transmission reach operating temperature more efficiently by converting motor energy into heat.
Implementation Method 1
the actuating piston of the shifting element is pre-filled with pressure medium. During this a certain amount of pressure medium is already delivered to the actuating piston
Implementation Method 2
determining the transmission condition with elevated drag losses
Data Source
AI summary
Disclosed is method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging gears of the vehicle transmission. In a neutral gear a transmission input (1) and a transmission output (2) of the vehicle transmission are decoupled from one another. In a driving gear the transmission input (1) and the transmission output (2) of the vehicle transmission are coupled with one another by closing the shifting elements (A, B, C, D, E) associated with the driving gear in order to propel the vehicle. When the neutral gear is engaged, a transmission condition is determined, and if a transmission condition with elevated drag losses exists, then in addition to the shifting elements (A, B, C, D, E) of a driving gear, at least one further shifting element (A, B, C, D, E) of the vehicle transmission is closed.