Hydraulic CVT Race Shifter for Stable Planetary Alignment
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Solution Overview
Problem
Existing continuously variable transmission (CVT) devices face challenges in efficiently adjusting transmission ratios due to limitations in axial separation mechanisms, leading to undesirable consequences such as axial displacement and potential damage from misalignment of planetary members.
Innovation Solution
The implementation of a hydraulic shifting mechanism that adjusts axial separation of radially inner and outer race structures through a hydraulic cavity system, utilizing torque-sensitive couplings and inclined plane structures to balance torque transmission and contact pressures, allowing for precise control of transmission ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical shifting mechanisms (springs, electric drive motors) are used to adjust axial separation of races, then transmission ratio can be changed, but axial displacement and misalignment of planetary members occur causing potential damage
Solution Approach 1:
The patent employs a hydraulic cavity system with hydraulic fluid to actuate the axial movement of inner and outer races. Hydraulic pressure applied to the cavity causes the races to move axially in a controlled manner, adjusting the transmission ratio without the misalignment and damage issues associated with mechanical shifting mechanisms like springs or electric motors.
2Power
If axial separation of races is increased to change transmission ratio, then torque transmission capability improves, but axial float of planetary members increases reducing stability
Solution Approach 1:
The patent incorporates torque-sensitive couplings that automatically adjust the axial separation of races in response to applied torque. When torque is applied to the input shaft, the coupling senses this and adjusts the race separation to maintain optimal contact pressure and planetary member alignment, providing feedback control that maintains stability while enabling torque transmission.
Solution Approach 2:
The system dynamically changes the axial separation parameter of the races based on operating conditions. The hydraulic cavity pressure and race axial position are adjusted as parameters to maintain optimal transmission characteristics across different torque loads, preventing excessive axial float while enabling adequate torque transmission capability.
3Measurement precision
If hydraulic cavity system is used to adjust axial separation, then transmission ratio control precision improves, but device complexity increases
Solution Approach 1:
The hydraulic cavity system serves multiple functions simultaneously: it acts as both the actuation mechanism for axial race movement and the control system for transmission ratio adjustment. The same hydraulic fluid pressure that moves the races also provides the force for torque transmission, eliminating the need for separate mechanical shifting mechanisms and reducing overall system complexity despite the hydraulic components.
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 solution enables efficient and compact transmission of torque between input and output shafts in both directions of rotation, maintaining symmetry and reducing axial 'float' of planetary members, thus enhancing the stability and efficiency of the CVT device.
Implementation Method 1
a hydraulic shifting mechanism that adjusts axial separation of radially inner and outer race structures through a hydraulic cavity system
Implementation Method 2
utilizing torque-sensitive couplings and inclined plane structures to balance torque transmission and contact pressures
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4C
AI summary
An outer race assembly for a continuously variable transmission includes a hydraulic cavity housing, a first radially outer race structure spaced along an axis from a second radially outer race structure to form a radially outer race, and planetary members in rolling contact with the radially outer race. The first radially outer race structure includes nesting engagement with the hydraulic cavity housing, and a hydraulic cavity sealed between the hydraulic cavity housing and the first radially outer race structure to control axial movement of the first radially outer race structure.