Vehicle Drivetrain Sailing Mode Shift Element Control
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Solution Overview
Problem
Existing vehicle drivetrain systems face challenges in efficiently activating and deactivating sailing operating states, leading to increased fuel consumption and higher production costs due to the need for additional hydraulic components.
Innovation Solution
A method for operating a vehicle drivetrain with a gearbox configured with positively engaging and frictionally engaging shift elements, allowing for seamless activation and deactivation of sailing modes by strategically managing shift element states and torque transfer capacities to optimize transmission ratios and reduce hydraulic fluid requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an electric auxiliary pump is added to supply hydraulic fluid to the gearbox during sailing operation, then the gearbox can be supplied with hydraulic fluid, but the structural space requirement and production costs increase
Solution Approach 1:
The patent extracts and removes the electric auxiliary pump from the system. Instead of adding a pump to supply hydraulic fluid during sailing operation, the invention uses the existing hydraulic pump integrated into the gearbox, which is already driven by the engine through the gearbox input shaft. This eliminates the need for additional components while maintaining hydraulic supply capability.
Solution Approach 2:
The existing hydraulic pump in the gearbox is made multi-functional. It serves both the normal operation of the gearbox and the sailing operation mode. By controlling the shift elements to be in specific states during sailing, the same hydraulic system that operates during normal driving continues to supply sufficient hydraulic fluid without requiring a separate auxiliary pump.
2Use of energy by moving object
If an electric auxiliary pump is added to supply hydraulic fluid to the gearbox during sailing operation, then the gearbox can be supplied with hydraulic fluid, but the production costs increase
Solution Approach 1:
The patent extracts and removes the electric auxiliary pump from the system. Instead of adding a pump to supply hydraulic fluid during sailing operation, the invention uses the existing hydraulic pump integrated into the gearbox, which is already driven by the engine through the gearbox input shaft. This eliminates the need for additional components while maintaining hydraulic supply capability.
Solution Approach 2:
The existing hydraulic pump in the gearbox is made multi-functional. It serves both the normal operation of the gearbox and the sailing operation mode. By controlling the shift elements to be in specific states during sailing, the same hydraulic system that operates during normal driving continues to supply sufficient hydraulic fluid without requiring a separate auxiliary pump.
3Speed
If shift elements are actuated quickly to enable spontaneous state transitions, then sailing operation can be activated and deactivated with high spontaneity, but the torque transfer capacity must be carefully managed to avoid excessive loads
Solution Approach 1:
The patent applies preliminary action by pre-positioning shift elements in specific states before sailing operation is activated. The control unit prepares the hydraulic system and shift element positions in advance, so when sailing mode is requested, the transitions occur rapidly and smoothly without sudden torque shocks. This preparatory positioning enables spontaneous activation while managing torque loads.
Solution Approach 2:
The patent uses dynamic control of shift element actuation. The control unit continuously monitors operating conditions and dynamically adjusts the actuation of shift elements based on current torque demands, vehicle speed, and sailing mode requirements. This dynamic approach enables fast state transitions while adapting torque transfer capacity to current operating conditions, avoiding excessive loads during spontaneous transitions.
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 enables efficient fuel savings, spontaneous state transitions, and reduced production costs by eliminating the need for an electric auxiliary pump, while maintaining gearbox performance and dynamics.
Implementation Method 1
multiple frictionally engaging shift elements, by which multiple toothed gear pairings of a gear set of the gearbox can be engaged and disengaged
Data Source
AI summary
A method for operating a vehicle drivetrain (1) includes decoupling, in the presence of a demand for realizing a sailing operating state of the vehicle drivetrain (1) during which a drive machine (2) is active and the power flow between the drive machine (2) and a drive output (3) is disconnected in a gearbox (4), the active drive machine (2) from the drive output (3) by opening of one of a plurality of shift elements (A to F) that is held in a closed operating state in order to realize the operating state present before the demand for decoupling of the active drive machine (2). The method also includes then actuating the plurality of shift elements (A to F) in a manner dependent on the present operating state profile of the vehicle drivetrain (1) and with the active drive machine (2) decoupled from the drive output (3).