Frictional Shifting Element Control for Rapid Vehicle Starting
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Solution Overview
Problem
Conventional automatic variable-speed transmissions in vehicle drive-trains cause significant delays between a driver's command to start and the actual movement of the vehicle, impairing spontaneity, especially in working machines like wheel loaders and forestry machines.
Innovation Solution
A method that adjusts the transmission capacity of a frictional shifting element in a continuously-variable power-branched transmission device to engage a starting transmission ratio quickly, reducing delays by varying the transmission ratio and torque applied to the shifting element, allowing for immediate implementation of a driver's start command without discomforting reaction torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuously-variable power-branched transmission system is used to adjust transmission ratio from infinite to long, then the transmission ratio can be continuously adjusted, but the spontaneity of the vehicle drive-train is impaired with perceptible time delays during starting processes
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the transmission capacity of the frictional shifting element before the actual starting command is executed. The control system prepares the shifting element with an optimized transmission capacity value that enables immediate torque transmission when the driver requests starting, thereby eliminating perceptible delays while maintaining continuous variability capability
Solution Approach 2:
The patent implements dynamics by continuously adjusting the transmission capacity of the frictional shifting element based on real-time operating conditions and driver input. The system dynamically optimizes the transmission ratio engagement process, transitioning from infinite to long transmission ratio without fixed stages, enabling spontaneous response to starting commands while maintaining adaptability
2Loss of time
If the transmission capacity of the frictional shifting element is increased to engage starting transmission ratio quickly, then the starting response time is reduced, but the load on the shifting element increases causing discomforting reaction torques
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transmission capacity parameter of the frictional shifting element during the starting process. The control system optimizes this parameter to achieve the minimum necessary value for quick engagement while preventing excessive values that would cause discomforting reaction torques, thereby balancing response time improvement with driving comfort
Solution Approach 2:
The patent implements feedback by continuously monitoring the transmission capacity of the frictional shifting element and adjusting it based on actual operating conditions. The control system uses feedback signals to prevent the transmission capacity from exceeding optimal values that would generate uncomfortable reaction torques, while ensuring it reaches sufficient values for rapid starting response
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
The method significantly reduces delays in starting processes, enhancing driving comfort and spontaneity by allowing for rapid engagement of the starting transmission ratio and efficient force flow, while minimizing load on the shifting element and maintaining driving comfort.
Implementation Method 1
a force flow between a drive mechanism and a drive output can be created with a frictional shifting element (5, 6) by appropriately adjusting the transmission capacity of the shifting element
Data Source
AI summary
A method of operating a vehicle drive-train during a starting process. The drive-train has a drive mechanism which can couple a continuously-variable power-branched transmission in which a plurality of transmission ratios can be engaged. The transmission ratios can be varied continuously by adjusting a variator, the transmission driving a drive output. A force flow between the drive mechanism and the drive output can be produced by a frictional shifting element by appropriately adjusting the transmission capacity of the shifting element. When a start command is issued, a starting transmission ratio is engaged in the area of the transmission device. During the engagement of the starting transmission ratio the transmission capacity of the frictional shifting element is adjusted to values greater than zero.