Electric Actuator Shock Absorbing Mechanism
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Solution Overview
Problem
Hydraulic cylinder devices used in tilt-trim devices for outboard motors are complex, heavy, and prone to oil leaks, making them difficult to reduce in size and weight, and pose an environmental risk due to their structure and operation.
Innovation Solution
An electric actuator with a screw shaft and nut mechanism that converts rotary motion into linear motion, incorporating a releasing mechanism and damping system to absorb impact loads, allowing the actuator to freely extend and retract without the need for hydraulic components, thus reducing size, weight, and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hydraulic cylinder device is used to raise/lower the outboard motor, then the motor can be positioned out of/into water, but the device becomes heavy and large in size
Solution Approach 1:
The patent replaces the hydraulic cylinder device with an electric actuator comprising an electric motor, screw shaft, and nut member. The electric motor rotates the screw shaft, which moves the nut member and output rod linearly through threaded engagement, eliminating the need for hydraulic fluid and complex valve systems while achieving the same motor positioning function.
Solution Approach 2:
The electric actuator is divided into distinct functional modules: the electric motor for power generation, the screw shaft for motion conversion, the nut member for linear displacement, and the output rod for force transmission. This segmentation allows for compact design and easier manufacturing compared to integrated hydraulic systems.
2Reliability
If a hydraulic cylinder device is used to protect from external force, then the swivel bracket can release freely under impact, but the structure becomes complicated with multiple valves and pipes
Solution Approach 1:
The patent removes the complex hydraulic valve and pipe system entirely, retaining only the essential mechanical components needed for impact protection. The releasing mechanism uses simple mechanical elements (engagement/projection features) rather than hydraulic control systems, achieving the same safety function with minimal complexity.
Solution Approach 2:
The releasing mechanism automatically responds to impact loads through mechanical force detection. When external force exceeds a threshold, the projection is forced out of the engagement groove, allowing automatic release without requiring hydraulic pressure changes or valve operations. The system self-regulates based on the applied load.
3Power
If a hydraulic cylinder device is used for motor positioning, then the function is achieved, but oil leakage occurs through pipes and valves
Solution Approach 1:
The patent eliminates hydraulic fluid and sealing requirements by replacing the hydraulic cylinder with a dry mechanical screw-nut mechanism. The electric motor drives the screw shaft, which directly converts rotational motion to linear motion of the output rod without requiring any fluid medium, thereby completely preventing oil leakage.
4Power
If a hydraulic cylinder device is used to raise/lower the motor, then positioning is achieved, but weight and size reduction becomes difficult
Solution Approach 1:
The output rod is designed to be retractable into the housing when not in use, similar to a nested structure. The screw shaft and nut member are compactly arranged within the housing, allowing the entire actuator to occupy minimal space while maintaining full positioning capability when activated.
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 electric actuator effectively replaces hydraulic cylinder devices by providing a compact, lightweight solution that prevents breakage from impact loads and eliminates the risk of oil leakage, ensuring safer and more environmentally friendly operation.
Implementation Method 1
a screw shaft, which is held by the housing so as to be rotatable, inserted into the hollow portion of the output rod, and is rotated by an electric motor as appropriate; and a nut member, which is provided to the output rod, mounted to the screw shaft, and is moved in an axial direction in accordance with rotation of the screw shaft
Implementation Method 2
a releasing mechanism provided between the drive cylinder and the movable cylinder, for engaging the movable cylinder with the drive cylinder and for allowing the movable cylinder to move with respect to the drive cylinder when a predetermined or more of axial force is applied to the movable cylinder fixed to the second structure
Data Source
AI summary
An electric actuator is capable of easily achieving reduction in weight and size when compared to a hydraulic cylinder device, capable of being used in place of the hydraulic cylinder device, and capable of freely extending in response to a suddenly-applied impact load. An electric actuator converts rotation of an electric motor into advancing/retracting motion of an output rod using a screw shaft and a nut member mounted to the screw shaft. The output rod includes: a drive cylinder, to which the nut member is provided, the drive cylinder being arranged around the screw shaft; and a movable cylinder arranged to overlap the drive cylinder around the screw shaft and freely advancing and retreating with respect to the drive cylinder. The electric actuator further includes a releasing mechanism provided between the drive cylinder and the movable cylinder, for engaging the movable cylinder with the drive cylinder.