Ship Helm Stop Mechanism with Inversion Control Pin

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Solution Overview

Problem

Conventional electric helm devices for boats face issues with the friction mechanism, where play in the engagement portion between disk tooth portions and spline members can lead to misalignment due to vibrations, making it difficult to securely cancel the locked state of the steering shaft during reversal.

Innovation Solution

A helm device with a stop mechanism that includes a rotation member, fixed and rotatable disks, an electromagnet, and an elastic member, along with an inversion control pin mechanism, which allows the steering shaft to be securely reversed by detecting the inversion allowance angle and adjusting it through the pin receiving stopper walls, enabling reliable locking and unlocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If play is provided in the engagement portion between disk tooth portions and spline members to allow reversal of the steering shaft, then the steering shaft can be reversed from the locked state, but the disks become misaligned due to vibrations during boat operation

Engineering Contradiction:
Improvereversal capabilityVSAvoiddisk alignment
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The invention introduces a wedge-shaped member as an intermediary component between the disks and the steering shaft. This wedge-shaped member fills the play in the engagement portion and transmits rotational force during reversal while maintaining disk alignment through its tapered geometry, which self-aligns the disks during the reversal motion

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention applies preliminary alignment action by using the wedge-shaped member to pre-position the disks in their correct rotational alignment before reversal occurs. The wedge shape ensures that as the steering shaft rotates during reversal, the disks are continuously guided back into alignment, preventing vibration-induced misalignment

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If an alignment mechanism is provided to maintain disk positions during reversal, then disk alignment is improved, but the structure becomes more complicated and the number of components increases

Engineering Contradiction:
Improvedisk alignmentVSAvoidstructure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The wedge-shaped member serves multiple functions simultaneously: it acts as a spacer to maintain the radial gap between disks, provides alignment during reversal through its tapered geometry, and transmits torque from the steering shaft to the disks. This multi-functionality eliminates the need for separate alignment mechanisms, reducing overall structural complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the alignment function with the existing friction mechanism components by integrating the wedge-shaped member into the space between the disks and steering shaft. This consolidation combines what would otherwise be separate alignment and friction components into a unified structure, simplifying the overall device

Inventive Principle:
Principle #5Merging (Combining)

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 solution ensures secure cancellation of the locked state during steering reversal, enhancing the reliability and safety of the helm device by allowing precise control over the steering effort and maintaining alignment despite vibrations.

Implementation Method 1

an electromagnet which produces the frictional force by pressing the fixed disk and the rotatable disk against each other

Methodology Applied
Scientific EffectElectromagnet: Electromagnet

Data Source

PatentEP2896558B1Ship helm apparatus
Publication Date: 2019.05.29 NHK SPRING CO LTD
  • EP2896558B1 patent drawingFigure 1~2
  • EP2896558B1 patent drawingFigure 3
  • EP2896558B1 patent drawingFigure 4

AI summary

A stop mechanism (23) of a helm device (16) includes a rotation member (80) which can be relatively rotated with respect to a steering shaft (22), rotatable disks (81), fixed disks (82) opposed to the rotatable disks (81), and an electromagnet (83) which presses these disks (81, 82) against one another. An inversion control pin (110) is provided in the steering shaft (22). Slits (120) are formed in a cylindrical portion (80a). Both ends of the inversion control pin (110) are inserted into the slits (120). The slits (120) are shaped to be elongated in a circumferential direction of the cylindrical portion (80a). A first pin receiving stopper wall (121) is formed on one end of the slits (120). A second pin receiving stopper wall (122) is formed on the other end of the slits (120). The inversion control pin (110) can move within the range of inversion allowance angle (θ) between the pin receiving stopper walls (121, 122).