Micrometer Constant Pressure Mechanism Axial Length Reduction

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Solution Overview

Problem

Conventional micrometers with constant pressure mechanisms have a large axial length due to the inclusion of coil springs and rotation transmitting rings, resulting in an increased size of the device.

Innovation Solution

A micrometer design featuring a ratchet ring with sawtooth projections and a biasing unit, where the ratchet claw and coil spring are positioned within the ratchet ring orthogonal to the spindle's axial direction, allowing for a shortened constant pressure mechanism and reduced overall size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coil spring and rotation transmitting rings are used in the constant pressure mechanism, then the constant pressure function is achieved, but the axial length of the mechanism increases

Engineering Contradiction:
Improveconstant pressure functionVSAvoidaxial length of constant pressure mechanism
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent repositions the coil spring from an axial arrangement to a radial arrangement within the ratchet ring. The spring acts radially inward on the ratchet爪, which converts this radial force into axial constant pressure through the ratchet engagement mechanism. This dimensional change eliminates the need for axial space previously occupied by the spring and rotation transmitting rings.

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

Solution Approach 2:

The patent integrates the coil spring, ratchet爪, and ratchet ring into a compact assembly where the spring is positioned within the ratchet ring structure. The rotation transmitting function is merged with the constant pressure function through the ratchet engagement, eliminating the need for separate rotation transmitting rings and reducing the overall mechanism length.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If the constant pressure mechanism includes traditional components (coil spring, rotation transmitting rings), then measurement accuracy is maintained, but the overall micrometer size increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidoverall micrometer size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent nests the coil spring within the ratchet ring structure, with the spring positioned radially inward. The ratchet爪 is integrated into this nested arrangement, allowing all three components (spring, ratchet爪, ratchet ring) to occupy a compact radial space rather than extending axially. This nesting maintains the constant pressure measurement function while significantly reducing the overall micrometer volume.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Length of moving object

If the ratchet claw and coil spring are positioned within the ratchet ring orthogonal to the axial direction, then the constant pressure mechanism length is shortened, but the structural complexity increases

Engineering Contradiction:
Improveconstant pressure mechanism lengthVSAvoidstructural complexity
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent employs asymmetric positioning of the coil spring and ratchet爪 within the ratchet ring, with the spring offset radially to engage the ratchet爪 at a specific point. This asymmetric arrangement efficiently converts radial spring force into axial constant pressure through the ratchet engagement geometry, achieving compact dimensions without requiring complex additional components or mechanisms.

Inventive Principle:
Principle #4Asymmetry

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 design effectively reduces the size of the micrometer by housing the ratchet claw and coil spring within the ratchet ring, enhancing usability and reducing production costs while maintaining accurate constant pressure measurement.

Implementation Method 1

a coil spring that biases the second rotation transmitting ring toward the first rotation transmitting ring

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2131140B1Micrometer
Publication Date: 2017.04.26 MITUTOYO CORP
  • EP2131140B1 patent drawingFigure 1
  • EP2131140B1 patent drawingFigure 2
  • EP2131140B1 patent drawingFigure 3

AI summary

A constant pressure mechanism (40) includes: a support shaft (41) including a shaft portion (411) that is provided on a base end of a spindle (20) coaxially with a center axis of the spindle (20) and inserted into a ratchet ring (33) of an operation section (30) and a head (412) of a diameter larger than the shaft portion (411) that is provided on a base end of the shaft portion (411); a ratchet claw (43) that is rotatable around a shaft (432) held by the head (412) and is provided with a sawtooth second projection (434) to be engaged with a first projection (332) on a lateral side thereof, the ratchet claw (43) being disposed within the ratchet ring (33); and a biasing unit (44) that biases the ratchet claw (43) toward the first projection (332). Since the above-described members (41,43,44) are disposed in a space within the ratchet ring (33) orthogonal to the axial direction of the spindle (20), the constant pressure mechanism (40) can be shortened in length along the axial direction of the spindle (20), thereby reducing the size of the micrometer.