Watercraft Propulsion Piston Structure for Longer Rod Stroke
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Solution Overview
Problem
Cylinder devices used in watercraft propulsion systems have limited piston rod stroke lengths, restricting their operational efficiency and versatility.
Innovation Solution
A piston structure body design featuring a through hole and inner and outer circumferential portions, where the first end face of the inner circumferential portion is positioned closer to the first face than the second end face of the outer circumferential portion, allowing for increased piston rod stroke length by offsetting the annular member and fixation member positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional piston structure is used, then the structure is simple and easy to manufacture, but the stroke length of the piston rod is limited
Solution Approach 1:
The piston is divided into distinct circumferential portions (first, second, third, and fourth circumferential portions) with different functions. The first portion interfaces with the piston rod, the second portion forms the through-hole, the third portion provides sealing surfaces, and the fourth portion supports the annular member. This segmentation allows each portion to be optimized independently, enabling increased stroke length while maintaining manufacturability.
Solution Approach 2:
The invention introduces a radial dimension to the piston structure by creating circumferential portions at different radial positions. The annular member is positioned radially outward from the piston rod, and the fixation members extend radially to secure it. This radial arrangement allows the piston rod to achieve greater axial stroke length without increasing the overall radial footprint of the piston assembly.
2Productivity
If the piston rod stroke length is increased, then operational efficiency improves, but the structural stability may be compromised
Solution Approach 1:
The annular member is pre-positioned on the piston rod before the piston reaches the end of its stroke. The fixation members (such as keys or set screws) are installed in advance to secure the annular member at a predetermined location. This preliminary positioning ensures that when the piston rod achieves maximum stroke length, the annular member remains stably fixed, preventing structural instability during operation.
Solution Approach 2:
The annular member acts as an intermediary element between the piston rod and the piston body. It distributes the mechanical loads from the piston rod across a larger area of the piston structure, reducing stress concentrations. The fixation members serve as intermediaries that mechanically connect the annular member to the piston rod, ensuring stable load transfer even when the stroke length is increased.
Data Source
AI summary
A piston structure body includes: a piston that includes a through hole, an inner circumferential portion, and an outer circumferential portion, the through hole being a hole that is formed to penetrate the piston axially through a center of a first face that is an end face on one end side in an axial direction, the inner circumferential portion defining the through hole and connected to the first face, the outer circumferential portion disposed to surround the inner circumferential portion and connected to the first face; and a piston rod that is inserted through the through hole. A first end face that is an end face of the inner circumferential portion on a back face side of the first face is positioned more closely to the first face than a second end face that is an end face of the outer circumferential portion on the back face side.