Chain Tensioner With Intersecting Tabs For Compact Mounting

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional chain tensioners are difficult to mount due to the need to manually keep the plunger retracted, and they tend to be large and heavy, making them cumbersome and inefficient.

Innovation Solution

A chain tensioner design featuring a radially elastically deformable setting ring with tabs that intersect the central axis, allowing the plunger to be easily retained in a retracted position within a stepped setting groove, reducing the housing size and weight while enabling easy mounting and automatic tension release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the tabs of the setting ring extend radially outwardly from the body of the setting ring to enable radial compression, then the setting ring can be easily compressed and engaged, but the housing outer diameter increases and weight increases

Engineering Contradiction:
Improveease of setting ring compressionVSAvoidhousing weight
Core Design Contradiction:
Ease of operationVSWeight of stationary object

Solution Approach 1:

The tabs extend in directions that intersect a plane perpendicular to the central axis of the setting ring, changing the orientation from radial to axial/intersecting. This dimensional change allows the tabs to be accessed and operated from the open end of the housing without increasing the radial outer diameter, thus reducing housing size and weight while maintaining ease of compression operation

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the plunger is always biased outwardly by the return spring to maintain chain tension, then the chain tension is maintained, but the housing must be fixed in position with the plunger kept pushed in, making mounting extremely troublesome

Engineering Contradiction:
Improvechain tension maintenanceVSAvoidmounting ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The setting ring is pre-configured to engage with the plunger and hold it in a retracted position before the chain tensioner is mounted. This preliminary action of pre-setting the plunger position eliminates the need to manually keep the plunger retracted during mounting, making installation easy while maintaining the reliability of chain tension through the return spring bias

Inventive Principle:
Principle #10Preliminary action

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

The design allows for effortless mounting and automatic tension adjustment, reducing the chain tensioner's size and weight, enhancing ease of installation and operational reliability.

Implementation Method 1

a return spring mounted in said housing and biasing said plunger outwardly of said housing

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

a radially elastically deformable setting ring having two separate opposed circumferential ends and received in said setting groove in a radially compressed state

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

A pushing force applied to the plunger from the chain is dampened by the oil in the pressure chamber, which is supplied into the pressure chamber through the oil supply passage

Methodology Applied
Scientific EffectViscous damping: Viscous Damping

Data Source

PatentEP2131066B1Chain tensioner
Publication Date: 2012.12.19 NTN CORP
  • EP2131066B1 patent drawingFigure 1
  • EP2131066B1 patent drawingFigure 2~3
  • EP2131066B1 patent drawingFigure 4~5

AI summary

The object is to provide a chain tensioner of which the plunger can be kept in a retracted position and of which the housing is small in size and light in weight. The chain tensioner comprises a cylindrical housing 1, a plunger 3 slidably mounted in the housing 1, and a return spring 7 mounted in the housing 1 and biasing the plunger 3 outwardly of the housing 1. The housing 1 is formed with a stepped setting groove 12 in a radially inner surface thereof near its open end. The setting groove 12 comprises a deep portion 12a and a shallow portion 12b. A radially elastically deformable setting ring 13 having two separate circumferential ends and received in the setting groove 12 in a radially compressed state. The setting ring 13 includes a pair of tabs 13a provided at the two separate circumferential ends, respectively, and received in a cutout 14 formed in the housing 1 at the open end. The setting ring 13 can be radially compressed by operating the tabs 13a. The plunger 3 can be retained in a position where the plunger 3 is pushed in the housing 1 by engaging the setting ring 13 in an engaging groove 15 formed in a radially outer surface of the plunger 3 near its front end, while keeping the setting ring 13 in elastic contact with a bottom of the shallow portion 12b of the setting groove 12. Thus, the tensioner can be easily mounted in position. The tabs 13a of the setting ring 13 extend in directions that intersect a plane perpendicular to a central axis of the setting ring 13. This makes it possible to reduce the wall thickness of the housing 1 and thus its size and weight.