Stationary Spindle Linear Drive for Ship Steering

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Solution Overview

Problem

Conventional ship steering gear linear drives face challenges in reliability and exposure to water, leading to potential failure and noise issues, especially in submerged submarines where external pressure is significant.

Innovation Solution

A linear drive design with a stationary spindle and movable spindle nut, sealed within a housing and connected to a thrust tube, utilizing a pressure equalization system and redundant electric motors to maintain operation and reduce noise, while keeping the spindle thread protected from water exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the spindle is made movable to drive the rudder directly, then the actuating force is improved, but the reliability deteriorates due to water exposure of the threaded spindle

Engineering Contradiction:
Improveactuating forceVSAvoidreliability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

Instead of making the spindle movable to drive the rudder, the invention inverts the approach by making the spindle stationary and the spindle nut movable. The spindle nut moves along the stationary threaded spindle, and this movement is transferred to the rudder through a thrust tube. This inversion protects the threaded spindle from water exposure while maintaining the necessary actuating force.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention extracts the threaded spindle from the water environment by making it stationary and enclosed. The movable component (spindle nut) operates in a protected environment, and only the necessary force transmission function is exposed to the water through the thrust tube mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

2Force

If the threaded spindle is exposed to water for direct rudder actuation, then the actuating capability is improved, but the noise increases due to water contact

Engineering Contradiction:
Improveactuating capabilityVSAvoidnoise
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

The invention inverts the conventional approach by making the spindle stationary and the spindle nut movable. This inversion prevents the threaded spindle from contacting water, thereby eliminating the noise generated by water contact while maintaining full actuating capability through the thrust tube mechanism.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If the spindle is made stationary with a movable spindle nut, then the reliability is improved by protecting the thread, but the device complexity increases due to the thrust tube requirement

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the functions of the spindle nut movement and rudder actuation by integrating the thrust tube mechanism. The thrust tube both transmits the linear movement of the spindle nut and provides structural support, combining multiple functions into a single integrated component that reduces overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If the spindle is made stationary, then the reliability is improved, but the power consumption increases due to the pressure equalization system

Engineering Contradiction:
ImprovereliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The pressure equalization system operates passively using the natural movement of the spindle nut and thrust tube. As the spindle nut moves, it automatically equalizes the pressure in the sealed housing without requiring additional power input. The system serves itself by utilizing the mechanical movement already present in the drive mechanism.

Inventive Principle:
Principle #25Self-service

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 enhances reliability and quiet operation by preventing water exposure and reducing power consumption, allowing the rudder to be held in position even if the electrical system fails, and ensures continued functionality with redundant motor arrangements.

Implementation Method 1

the first seal forms a sealing connection with the first housing; the second seal forms a sealing connection with the first housing

Methodology Applied
Scientific EffectSealing:

Implementation Method 2

the fluid has spindle-lubricating properties

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

a pressure equalization system

Methodology Applied
Scientific EffectPressure equalization:

Data Source

PatentEP3429920B1Linear drive for a ship steering engine
Publication Date: 2020.04.29 THYSSENKRUPP AG
  • EP3429920B1 patent drawingFigure 1

AI summary

The present invention relates to a linear drive for a ship steering engine comprising a spindle (10) and a spindle nut (20). The spindle nut (20) is connected to a propulsion pipe (30). The spindle (10) is fixedly mounted and the spindle nut (20) and the propulsive pipe (30) are moved linearly.