Outboard Motor Steering System with Nested Dual-Motor Feed Screw
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Solution Overview
Problem
Conventional electric steering apparatuses for outboard motors have large longitudinal dimensions due to projecting drive system components, which can interfere with other boat components and expose protective boots to seawater, leading to potential damage.
Innovation Solution
A compact steering apparatus design featuring a dual-electric motor system with a feed screw rotated by both motors, housed within a cover member with protective boots that expand and contract, reducing the radial dimension and protecting the boots from damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional electric steering apparatus uses a rack and pinion with projecting drive system components, then the steering function is achieved, but the longitudinal dimension becomes large and components interfere with other boat parts
Solution Approach 1:
The feed screw is rotated by two electric motors positioned at opposite ends, with the motors nested within the cover member structure. The protective boots are disposed inside the cover member, nesting the feed screw and protective boots within the compact cover member housing, reducing the overall longitudinal dimension while preventing interference with other boat components
2Reliability
If protective boots are exposed to the outside in conventional designs, then the rack and pinion are protected from seawater, but the protective boots can be damaged by cables and fuel supply pipes
Solution Approach 1:
The protective boots are disposed inside the cover member, nesting them within the protected interior space. This positioning protects the protective boots from external damage by cables and fuel supply pipes while maintaining their function of protecting the rack and pinion from seawater erosion
Solution Approach 2:
The cover member acts as an intermediary structure that houses and protects both the feed screw mechanism and the protective boots. It provides a protective environment that shields the boots from external hazards while allowing them to perform their waterproofing function
3Ease of operation
If drive system components project downward when outboard motor is tilted up, then the steering mechanism remains accessible, but the components interfere with members on the boat body
Solution Approach 1:
The feed screw, protective boots, and electric motors are all nested within the cover member housing. This compact nesting arrangement ensures that when the outboard motor is tilted up, the drive system components do not project downward to interfere with boat body members, while the steering mechanism remains accessible through the helm
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 compact design minimizes interference with boat components and prevents protective boot damage by housing the feed screw and boots within a cover member, ensuring reliable operation and protection from seawater.
Implementation Method 1
a feed screw disposed along the cover member inside the cover member and configured to be rotated by respective torques of the first and second electric motors
Implementation Method 2
a nut member threadedly engaged with the feed screw and configured to move along an axis of the feed screw inside the cover member as the feed screw rotates
Implementation Method 3
protective boots disposed inside the cover member that cover the feed screw in such a manner that the protective boots can expand and contract along the axis of the feed screw
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Support arms (40, 41) are disposed on a tilting shaft (32) on a bracket (30) of an outboard motor. An electric actuator (50) is mounted between the support arms (40, 41). The electric actuator (50) includes a cover member (51), first and second electric motors (52, 53) disposed individually on the opposite ends of the cover member (51), a feed screw (54) configured to be rotated by the electric motors (52, 53), a nut member (70) configured to move along an axis (X1) as the feed screw (54) rotates, a drive arm (71) configured to move integrally with the nut member (70) and transversely relative to the boat body (11), and protective boots (80, 81). The drive arm (71) is connected to a steering arm (35) through an engaging member (73). If the drive arm (71) moves in the direction of the axis (X1) along the cover member (51), the steering angle of the steering arm (35) changes depending on the degree of movement of the drive arm (71).