Drive Belt Element Assembly to Prevent Hoop Detachment

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Solution Overview

Problem

The existing drive belt configurations, such as those described in JP 2017-516966 A, face issues with elements detaching from the hoop due to increased clearance between adjacent elements caused by elongation, abrasion, or buckling, leading to potential disengagement and detachment under vibrations.

Innovation Solution

The drive belt design incorporates a hoop with an inner and outer peripheral surface and side surfaces, along with elements featuring a base portion, pillars, hooks, and displacement-restriction surfaces, where the first and second hooks have specific dimensions and orientations to securely assemble and maintain the elements in a loop, preventing detachment by restricting relative displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If only one large hook is provided on each element, then the element and hoop can be easily assembled together, but the element may detach from the hoop under vibrations when clearance increases

Engineering Contradiction:
Improveease of assemblyVSAvoidretention reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies local quality by providing different hook sizes at different locations on the element. The first hook (larger size) is positioned to facilitate easy assembly with the hoop, while the second hook (smaller size) is positioned to provide secure retention and prevent detachment under vibrations. This differential hook design allows each local region of the element to serve its specific function optimally.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies preliminary action by pre-positioning two hooks on the element before assembly with the hoop. The first hook is preliminarily configured to guide and receive the hoop during assembly, while the second hook is preliminarily configured to engage with the hoop to prevent future detachment. This preliminary configuration ensures both easy assembly and reliable retention without requiring additional components or steps.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the second hook is made significantly smaller to avoid interference during assembly, then assembly is easier, but the hook cannot reliably prevent detachment under vibrations

Engineering Contradiction:
Improveease of assemblyVSAvoidholding strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent applies local quality by making the second hook significantly smaller than the first hook. The smaller second hook is positioned to engage with the hoop in a way that prevents interference during assembly while still providing sufficient holding strength to prevent detachment under vibrations. The local optimization of hook size at this specific location resolves the contradiction between ease of assembly and holding strength.

Inventive Principle:
Principle #3Local quality

3Duration of action of moving object

If clearance between adjacent elements increases due to elongation or wear, then the element becomes more prone to disengagement, but the hoop structure remains the same

Engineering Contradiction:
Improveservice lifeVSAvoidengagement reliability
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-configuring two hooks on each element before assembly with the hoop. The first hook is preliminarily positioned to facilitate easy assembly, while the second hook is preliminarily positioned to provide secure retention. This preliminary dual-hook configuration ensures that even when clearance increases due to elongation or wear during service life, the elements remain reliably engaged with the hoop and do not detach.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3462056B1Drive belt
Publication Date: 2021.08.18 TOYOTA JIDOSHA KK
  • EP3462056B1 patent drawingFigure 1
  • EP3462056B1 patent drawingFigure 2
  • EP3462056B1 patent drawingFigure 3

AI summary

A drive belt (1) includes a hoop (2) and multiple elements (3) joined together in a loop by the hoop (2). Each element (3) has an assembly space (17) into which one end portion (2f) of the hoop (2) is inserted during assembly. Each element (3) is configured such that a first opening width (W1), which is a distance between a first hook (8) and a second hook (9), is less than a width (WF) of the hoop (2), and a second opening width (W2), which is a distance between the second hook (9) and a contact site (6f) where the one end portion (2f) of the hoop (2) housed in the assembly space (17) contacts a first pillar (6), is greater than the width (WF) of the hoop (2). The first hook (8) and the second hook (9) respectively include a first displacement-restriction surface (14) and a second displacement-restriction surface (15) each configured to restrict relative displacement between the element (3) and the hoop (2) by contacting a corresponding one of edges (2c) of the hoop (2).