Marine Steering Actuator Layout for Axial Constraint and Torque Transfer
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Solution Overview
Problem
Existing marine steering systems face challenges in efficiently and reliably providing steering movement and torque distribution due to limitations in the design of electric actuators, particularly in terms of axial movement inhibition and reaction torque constraint.
Innovation Solution
The electric actuator design includes a housing with a reciprocating output shaft, a motor with a radial drive mechanism such as a belt or idler gear, a position sensor with gear reduction, and a clutch functioning as a brake, all integrated within a T-shaped housing profile to ensure effective steering and torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional electric actuator design is used with the motor output shaft aligned with the actuator output shaft, then the structure is simpler, but the motor cannot remain within the actuator housing in all propulsion unit positions
Solution Approach 1:
The drive mechanism is positioned on a plane radial to the longitudinal axis of the motor output shaft, transitioning from a coaxial arrangement to a radial plane arrangement. This dimensional change allows the motor to remain within the actuator housing while accommodating the propulsion unit in tilted positions, as the radial drive mechanism can accommodate angular displacement better than a coaxial arrangement.
2Ease of operation
If the output shaft is allowed to move axially freely, then the reciprocating motion is easier to achieve, but axial movement inhibition is required for proper steering operation
Solution Approach 1:
The output shaft is segmented into a threaded portion and a smooth portion. The threaded portion engages with the rotor threads to enable reciprocating motion through rotational movement, while the smooth portion passes through the housing to allow rotational constraint without axial movement. This segmentation allows the output shaft to achieve reciprocating motion through rotation rather than direct axial movement, eliminating the need for separate axial constraint mechanisms.
3Volume of moving object
If the housing is designed with a compact profile, then the actuator size is reduced, but adequate space for all components including wiring and drive mechanism is required
Solution Approach 1:
Wiring is routed along the longitudinal axis of the actuator output shaft, utilizing the axial dimension rather than requiring radial or lateral space. This allows wiring to be accommodated within the compact housing volume without interfering with the radial drive mechanism or other components, maintaining a compact overall size while providing adequate space for all components.
Solution Approach 2:
The T-shaped housing profile with longitudinally extending arm portions serves multiple functions: it provides structural support, defines the compact envelope, and creates pathways for wiring and mounting. The arm portions extend to accommodate wiring along the longitudinal axis while maintaining a compact overall footprint, making the housing structure multi-functional and highly space-efficient.
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 configuration enhances the marine steering system's ability to provide precise and reliable steering by inhibiting axial movement, distributing torque effectively, and allowing for precise position sensing and control, while maintaining a compact and adaptable design.
Implementation Method 1
The drive mechanism may include a belt which couples the output shaft of the electric actuator to the rotor. The belt may be provided with a tensioner.
Implementation Method 2
The drive mechanism includes an idler gear which couples the output shaft of the electric actuator to the rotor.
Data Source
AI summary
An electric actuator for a marine steering system comprises a housing and an output shaft reciprocatingly received by the housing. There is a rotor disposed within the housing. The rotor is coupled to the output shaft of the electric actuator. Rotation of the rotor causing the output shaft of the electric actuator to reciprocate relative to the housing. There is a motor disposed within the housing. The motor has an output shaft coupled to the rotor. A longitudinal axis of the output shaft of the motor is parallel with a longitudinal axis of the output shaft of the electric actuator. There is also a drive mechanism disposed within the housing. The drive mechanism couples the output shaft of electric actuator to the rotor. The drive mechanism is on a plane radial to a longitudinal axis of the output shaft of the motor.