Planetary Cone CVT Layout for Bearing Durability and Efficiency
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Solution Overview
Problem
Existing continuously variable transmissions using planetary rollers face challenges in transmitting large torque without causing slippage, which can lead to reduced power transmission efficiency and deteriorated bearing durability.
Innovation Solution
The continuously variable transmission employs a configuration where the contact positions between the planetary cone and the sun roller and ring roller are maintained parallel to the input shaft axis, utilizing a ball cam mechanism and elastic members to manage contact pressures and prevent turning moments on the support shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If contact pressure between planetary rollers and input/output rings is increased to transmit larger torque, then torque transmission capability is improved, but frictional resistance increases reducing power transmission efficiency
Solution Approach 1:
The patent changes the geometric parameters of the planetary rollers, specifically using conical surfaces with optimized angles and dimensions. This allows achieving higher torque transmission through improved contact geometry rather than simply increasing contact pressure, thereby maintaining power transmission efficiency while transmitting larger torque.
Solution Approach 2:
The patent employs conical surfaces and curved contact interfaces between planetary rollers and input/output rings. The curved geometry distributes contact pressures more effectively and reduces sliding friction compared to flat surfaces, improving both torque transmission capability and power transmission efficiency simultaneously.
2Force
If contact pressure is increased to increase transmission torque, then torque transmission capability is improved, but load on supporting bearings increases deteriorating durability
Solution Approach 1:
The patent optimizes the conical angle and dimensional parameters of planetary rollers to distribute bearing loads more favorably. By changing geometric parameters rather than simply increasing contact pressure, the system achieves higher torque transmission while controlling bearing loads within acceptable limits for maintained durability.
Solution Approach 2:
The patent employs multiple planetary rollers arranged symmetrically around the input shaft, creating balanced load distribution. The gravitational and centrifugal forces on multiple rollers counterbalance each other, reducing the net load on individual supporting bearings while maintaining high torque transmission capability through the collective action of all rollers.
3Force
If contact pressure between input roller and planetary roller is increased, then torque transmission is improved, but frictional resistance increases reducing power transmission efficiency
Solution Approach 1:
The patent uses conical contact surfaces between the input roller and planetary rollers, replacing flat or cylindrical interfaces. The conical geometry provides optimal contact angles that reduce sliding friction while maintaining necessary contact pressures for torque transmission, thereby improving power transmission efficiency even at higher torque levels.
Solution Approach 2:
The patent optimizes the conical angle parameter of the contact surfaces to achieve the best balance between torque transmission and friction reduction. By precisely controlling this geometric parameter, the system maximizes power transmission efficiency while maintaining sufficient contact pressure for the required torque capacity.
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 configuration effectively prevents deterioration in bearing durability and maintains power transmission efficiency, allowing for smooth and efficient torque transmission while changing the transmission ratio.
Implementation Method 1
a loading cam mechanism generating a thrust load in the central axis direction
Implementation Method 2
an elastic member which applies an elastic force to the planetary cone 5
Data Source
Figure 1
Figure 2
Figure 3
AI summary
[Problem to be Solved] There is provided a continuously variable transmission (1) that can prevent deterioration in the durability of a bearing that supports a planetary cone and can prevent reduction in the power transmission efficiency. [Solution] In the continuously variable transmission (1), a contact position (P1) between a conical surface (14d, 15d) of a planetary cone (5) and a sun roller (2A) and a contact position (P2) between a conical surface (14d, 15d) of the planetary cone (5) and a ring roller (6) are in the same position in an axial direction of an input shaft (2). Additionally, the contact position (P1) of the conical surface (14d) of the planetary cone (5) with the sun roller (2A) and the contact position (P2) of the conical surface (15d) of the planetary cone (5) with the ring roller (6) both extend substantially parallel to the input shaft (2). Additionally, the planetary cone (5) includes an input-side planetary cone (14) in contact with the sun roller (2A), an output-side planetary cone (15) provided separately from the input-side planetary cone (14) and in contact with the ring roller (6), and an elastic member (5A) provided in a compressed state between a bottom surface (14b) of the input-side planetary cone (14) and a bottom surface (15b) of the output-side planetary cone (15).