Reversible Variable Transmission Pressure Control Near Traction Limit
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Solution Overview
Problem
Current reversible variable transmissions face limitations in power density and efficiency due to design constraints, particularly in sustaining high squeezing pressures and optimizing torque transfer, leading to internal losses and reduced performance near the traction limit.
Innovation Solution
The design enhances power density by increasing normal forces on traction wheels, integrating a control method to operate closer to the traction limit, and incorporating improvements such as a double mantle planet wheel structure, asymmetric planet fork legs, and advanced bearing configurations to reduce power losses and vibrations, along with electronic and mechanical slip protection mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If normal forces on traction wheels are increased to improve power density, then power transmission capability is improved, but internal losses and power losses increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the squeezing pressure within an optimal range (20-150 bar) to maximize power transmission while minimizing internal losses. The electronic control system continuously adjusts operational parameters to maintain optimal efficiency, preventing excessive pressure that would cause disproportionate energy losses.
Solution Approach 2:
The patent implements feedback mechanisms through electronic control systems that monitor transmission performance and adjust operational parameters in real-time. This feedback loop ensures the transmission operates close to the traction limit without exceeding optimal pressure thresholds, thereby maximizing power density while controlling internal losses.
2Force
If squeezing pressure is increased to improve torque transfer, then torque transmission is improved, but power losses increase
Solution Approach 1:
The patent optimizes the balance between squeezing pressure and torque transfer by maintaining pressure within the 20-150 bar range. This parameter optimization ensures sufficient normal forces for effective torque transmission while preventing excessive pressure that would cause disproportionate power losses in the rolling contacts.
3Power
If the transmission operates closer to the traction limit to improve efficiency, then power density is improved, but reliability and slip protection become more challenging
Solution Approach 1:
The patent employs electronic control systems with feedback mechanisms that continuously monitor transmission slip and operational parameters. When approaching the traction limit, the system provides slip protection by adjusting squeezing pressure or operational conditions, ensuring reliable operation while maintaining high power density near the optimal efficiency point.
4Loss of energy
If advanced bearing configurations and structural improvements are implemented to reduce power losses, then efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the planet wheel into a double-mantle structure, allowing independent optimization of each mantle for reduced power losses. The asymmetric planet fork legs are another example of segmentation, where each leg can be optimized for its specific functional requirements, reducing overall power losses while maintaining manageable complexity through modular design.
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 enhanced design achieves higher power density and efficiency by maintaining optimal squeezing pressures, reducing internal losses, and ensuring reliable torque transfer, thereby improving the overall performance and durability of the transmission system.
Implementation Method 1
The planets consist of a planet wheel with basically a conical rolling surface, preferably hardened or coated to transmit tractional and compressive forces
Implementation Method 2
The ring wheel, planets and sun wheel are squeezed against each other so that the rolling surfaces are in contact with each other and that the contact pressures are high enough to transmit the required torque
Data Source
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AI summary
The invention provides design modifications to increase the power density of a reversible variable transmission system for vehicles such as cars, buses, trucks, off-road vehicles, lift trucks, telescopic boom handlers and the like. The transmission can also be used in systems such as windmills etc. and other industrial applications that require power to be transferred at variable speeds.