CVT Clutch Peak Torque Limiter for Downstream Torque Spikes

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Solution Overview

Problem

Existing CVT systems face challenges in handling high inertial torque during power-on and power-off situations, leading to downstream torque spikes, which necessitate oversized components, increasing costs and weight.

Innovation Solution

A CVT clutch with an internal peak torque limiter that allows downstream components to be sized for normal duty cycle loads, featuring a fixed and movable sheave, a spider, a cam assembly, and a bias member, where the peak torque limiter slips when torque exceeds a set maximum threshold, preventing torque spikes from being transmitted.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If downstream components are oversized to handle high inertial torque during power-on and power-off landings, then reliability is improved, but weight and cost increase

Engineering Contradiction:

Improveability to handle torque spikesVSAvoidweight of downstream components

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

A peak torque limiter device is introduced as an intermediary component between the drivetrain and downstream components. This mediator limits torque spikes to a predetermined threshold level, protecting downstream components from excessive torque while allowing them to be sized for normal operating conditions rather than peak transient loads.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The peak torque limiter provides beforehand cushioning by being pre-configured with a slip threshold that engages automatically when torque exceeds the threshold. This preemptive protection mechanism cushions downstream components from torque spikes before they can cause damage, eliminating the need for oversized protective components.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If downstream components are oversized to handle high inertial torque during power-on and power-off landings, then reliability is improved, but cost increases

Engineering Contradiction:

Improveability to handle torque spikesVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The peak torque limiter serves as a cost-effective intermediary that protects downstream components from torque spikes. By introducing this relatively simple limiting mechanism, downstream components can be manufactured at lower cost using standard sizing rather than expensive oversized components designed for peak torque conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The peak torque limiter is designed as a simpler, more economical component that can be replaced if needed, whereas downstream components are sized for normal operation and become more valuable and expensive assets. The limiter acts as a sacrificial protection device that is cheaper than the alternative of oversizing expensive downstream components.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If a peak torque limiter is added to the CVT clutch, then torque spike management is improved, but device complexity increases

Engineering Contradiction:

Improvetorque spike protectionVSAvoidclutch assembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The peak torque limiter is merged with the existing CVT clutch assembly rather than being a separate external device. The limiter utilizes the existing spider, cam assembly, and bias member structures of the clutch, integrating the torque limiting function into the clutch's normal operation and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The spider and cam assembly structures serve multiple functions: they provide the mechanical linkage for clutch operation and simultaneously serve as the torque-limiting mechanism. The bias member both engages the clutch plates and sets the torque threshold for the peak torque limiter, eliminating the need for separate dedicated torque limiting components.

Inventive Principle:

Principle #6Universality (Multi-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

Enables the use of normally sized downstream components while effectively managing torque spikes, reducing vehicle weight and cost without compromising performance.

Implementation Method 1

The PTL is configured to slip when exposed to a torque over a set maximum toque threshold

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

The bias member is configured to exert a bias force on the spider to engage the clutch pack to allow the torque transfer between the spider and the post

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11994213B2Continuously variable transmission clutch with a peak torque limiter

Publication Date: 2024.05.28 TEAM IND INC

AI summary

A continuously variable transmission (CVT) clutch that includes a post, a fixed sheave, a moveable sheave and a peak torque limiter (PTL) is provided. The fixed sheave is rotationally mounted on the post. The fixed sheave is axially fixed in relation to the post. The moveable sheave is rotationally mounted on the post. The moveable sheave is configured to move axially on the post. The PTL operationally couples at least the moveable sheave to the post. The PTL is configured to slip when exposed to a torque over a set maximum toque threshold.