Spider Gear CVT Assembly for High-Torque Ratio Variation
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Solution Overview
Problem
Continuously variable transmissions (CVTs) face limitations in torque transmission due to frictional engagement and have a high number of moving parts, which affects durability and increases design, manufacturing, and maintenance costs.
Innovation Solution
A transmission assembly that uses a spider gear system with roller bearings and a hydraulic circuit to provide a continuously variable gear ratio without relying on belts or chains, featuring a load controller and powertrain controller to manage torque and rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a belt or chain frictionally engages a pair of rotatable pulleys to provide continuous variable gear ratios, then the transmission can continuously vary the rotational speed of the output device, but the amount of torque that may be transmitted is limited
Solution Approach 1:
The patent replaces the traditional belt-and-pulley friction-based mechanical system with a gear-based mechanical system. Specifically, it uses a planetary gear set with a sun gear, planet gears, and a ring gear, where gear teeth provide positive mechanical engagement instead of frictional contact. This substitution enables higher torque transmission capacity while maintaining continuously variable gear ratio capability through controlled engagement and disengagement of gear teeth.
Solution Approach 2:
The patent introduces a hydraulic system with a piston, cylinder, and controllable valve to manage the engagement and disengagement of the planet gears with the ring gear. By using hydraulic pressure, the system can smoothly control the mechanical engagement state, enabling continuous variation of the effective gear ratio while handling high torque loads that would be impossible with friction-based systems alone.
2Adaptability or versatility
If a CVT includes a relatively large number of moving parts to achieve continuous variable gear ratios, then the gear ratio can be continuously adjusted, but the durability is limited and the effort and cost to design, manufacture, maintain, and repair increases
Solution Approach 1:
The patent merges multiple functions into the planetary gear set structure. The sun gear, planet gears, ring gear, and carrier assembly work together as an integrated mechanism that provides both the structural framework and the gear ratio variation capability. This consolidation reduces the need for separate components and mechanisms that would otherwise be required in traditional CVT designs, thereby reducing overall part count and complexity.
Solution Approach 2:
The planetary gear set serves multiple functions simultaneously: it provides the mechanical structure for gear ratio variation, transmits high torque through gear tooth engagement, and enables continuous adjustment through hydraulic control of planet gear engagement. This multi-functionality eliminates the need for dedicated components for each function, reducing the total number of moving parts while maintaining CVT capabilities.
3Adaptability or versatility
If a CVT uses frictional engagement between belt and pulley, then continuous variable gear ratio is achieved, but mechanical wear occurs and maintenance costs increase
Solution Approach 1:
The patent replaces the friction-based belt-pulley interaction with gear-tooth meshing. The planet gears engage with the ring gear through interlocking teeth that provide positive mechanical contact rather than frictional sliding. This eliminates the wear and heat generation associated with frictional engagement, significantly improving reliability and reducing maintenance requirements while preserving continuous variable gear ratio functionality.
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 solution enhances torque transfer efficiency and durability by allowing continuous rotation of spider gears and varying gear ratios without mechanical wear, reducing maintenance and production costs.
Implementation Method 1
a hydraulic circuit in fluid communication with the load applicator and configured to receive the force from the load applicator
Implementation Method 2
A transmission assembly that uses a spider gear system with roller bearings and a hydraulic circuit to provide a continuously variable gear ratio
Implementation Method 3
a ring gear with a plurality of gear teeth disposed on an outer surface, the plurality of gear teeth of the ring gear being in meshed engagement with the plurality of gear teeth of the input gear
Data Source
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AI summary
A transmission assembly includes a ring gear configured to receive an input torque from a power source, a carrier assembly coupled to the ring gear, the carrier assembly configured to rotate about a first axis and including a housing, and a spider gear rotatably coupled to the housing, a carrier outlet shaft including a carrier outlet gear in meshed engagement with the spider gear, wherein the carrier outlet shaft is configured to transmit an output torque to a driveshaft, a control shaft including a control gear in meshed engagement with the spider gear, and a load applicator coupled to the control shaft, wherein the load applicator is configured to provide a resistive torque to the control shaft to resist rotation of the control shaft and vary a gear ratio between the driveshaft and the input shaft.