CVT Actuator Stroke Adjustment via Manual Nut Rotation

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Solution Overview

Problem

The existing belt-type continuously variable transmission systems face challenges in adjusting the stroke position of the threaded shaft when using a screw feed mechanism with lower reverse efficiency, making it difficult to mount the actuator on a transmission case without prior precise adjustment, and are costly due to the use of ball screws.

Innovation Solution

A belt-type continuously variable transmission system with an actuator that includes a screw feed mechanism with a nut member and threaded shaft, where the nut member can be rotated independently of the motor power, and features a restriction mechanism to limit the stroke length and prevent accidental disengagement, allowing for easier adjustment of the stroke position and improved assembly ease.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ball screw is used as the screw feed mechanism, then the reverse efficiency is high and the threaded shaft can easily carry out a stroke, but the cost increases

Engineering Contradiction:
Improvereverse efficiencyVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive ball screw with a simpler, cheaper screw feed mechanism that uses a nut member and threaded shaft without ball recirculation components. This substitution reduces manufacturing cost while maintaining sufficient functionality for the application.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Ease of manufacture

If a screw feed mechanism not employing a ball is used, then the cost decreases, but the reverse efficiency is lower and the threaded shaft cannot simply carry out a stroke

Engineering Contradiction:
ImprovecostVSAvoidstroke adjustment
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent incorporates a preliminary adjustment mechanism that allows the stroke position of the threaded shaft to be set before the actuator is mounted on the transmission case. This preliminary positioning capability compensates for the lower reverse efficiency of the non-ball screw mechanism, enabling easy installation without requiring precise pre-adjustment during assembly.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the stroke position of the threaded shaft is adjusted in advance before mounting, then the assembly precision is improved, but the ease of operation during mounting decreases

Engineering Contradiction:
Improvestroke position precisionVSAvoidmounting ease
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent makes the stroke position adjustable and adaptable during the mounting process rather than fixed in advance. The actuator design allows for dynamic adjustment of the threaded shaft stroke position after mounting, providing flexibility to accommodate variations in installation conditions while maintaining precise positioning when needed.

Inventive Principle:
Principle #15Dynamics

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

Enables easy adjustment of the stroke position of the threaded shaft even when the reverse efficiency of the screw feed mechanism is lower, improving assembly ease and preventing accidental disengagement, while reducing costs by allowing for non-precise initial adjustments.

Implementation Method 1

a screw feed mechanism that includes a nut member and a threaded shaft, the nut member being rotated by receiving rotational power of the motor, the threaded shaft converting rotation of the nut member into linear motion

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3379104B1Belt-type continuously variable transmission
Publication Date: 2020.10.07 MUSASHI SEIMITSU INDUSTRY CO LTD
  • EP3379104B1 patent drawingFigure 1
  • EP3379104B1 patent drawingFigure 2
  • EP3379104B1 patent drawingFigure 3

AI summary

Since a belt-type continuously variable transmission is provided with an operation part (25) which can rotate the nut member (21) without depending on the rotational power of the motor (19), it is possible to make the threaded shaft (13) stroke by operating the operation part (25) and rotating the nut member (21). Therefore, even when a screw feed mechanism in which the reverse efficiency of a screw is lower than the forward efficiency is used, it is possible to easily adjust the stroke position of the threaded shaft (13). Thus, it is possible to provide a belt-type continuously variable transmission that enables the stroke position of a threaded shaft to be easily adjusted even when a screw feed mechanism in which the efficiency of converting linear motion of the threaded shaft into rotary motion is lower than the efficiency of converting rotary motion into linear motion is used.