Trim and Tilt Device Rod Guide Stepped Configuration
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Solution Overview
Problem
Existing trim and tilt devices for boat propulsion systems face wear issues due to increased forces on sliding components when the outboard motor outputs high thrust, which can lead to premature wear, and increasing the length of these components to reduce pressure results in a shortened movable range, limiting the achievable tilt angle.
Innovation Solution
The design modifies the axial lengths of the rod guide and piston surfaces to reduce wear by making the outer peripheral surface of the rod guide shorter and the inner surface longer, and the outer peripheral surface of the piston longer and inner surface shorter, allowing for reduced pressure distribution without shortening the movable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the length of the sliding portion is increased to reduce pressure and prevent wearing, then the wearing of the sliding portion is reduced, but the movable range of the piston is shortened
Solution Approach 1:
The invention changes the dimensional configuration of the rod guide by making the axial length of the inner peripheral surface longer than that of the outer peripheral surface. This creates a stepped configuration where the rod guide has different lengths in different radial dimensions, allowing the sliding portion to be extended in the axial direction without increasing the overall size of the rod guide in other dimensions. This resolves the contradiction by enabling increased sliding portion length while maintaining compact overall dimensions that preserve piston movable range.
Solution Approach 2:
The invention applies local quality by creating a stepped configuration on the rod guide where only the specific region that contacts the rod (the inner peripheral surface) is extended in length, while the outer peripheral surface maintains a shorter length. This localized extension of the sliding portion allows increased wearing resistance at the critical contact area without requiring a uniform increase in the overall size of the rod guide, thereby preserving the piston's movable range.
2Reliability
If the axial length of the rod guide outer peripheral surface is increased to reduce pressure on the sliding portion, then the wearing is reduced, but the overall size of the trim and tilt device increases
Solution Approach 1:
The invention resolves the contradiction between wearing resistance and device size by changing the dimensional configuration of the rod guide. Instead of uniformly increasing the axial length of the entire rod guide outer peripheral surface, the invention extends only the inner peripheral surface that contacts the rod, creating a stepped configuration. This allows increased sliding portion length for better wearing resistance while keeping the overall outer dimensions compact, thus preventing device size increase.
Solution Approach 2:
The invention applies local quality by selectively extending only the critical sliding contact region (inner peripheral surface) of the rod guide while keeping the outer peripheral surface at a shorter length. This localized extension concentrates the wear-reduction function in the specific area where it is needed, without requiring a uniform increase in the overall size of the rod guide, thereby maintaining compact device dimensions.
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 reduces wear on sliding components while maintaining the necessary movable range, ensuring effective tilt angle adjustment and preventing component wear, even under high thrust conditions.
Implementation Method 1
When the supply and discharge device supplies the hydraulic oil to an oil chamber in the cylinder, the piston in the cylinder moves in an axial direction and the rod moves forward and backward relative to the cylinder
Data Source
AI summary
A trim and tilt device includes: a cylinder; a piston; a rod; and a rod guide. The rod includes a first end to which the piston is fixed, and the piston includes an insertion hole to which the first end of the rod is inserted. Over an entire periphery of the rod guide, a lower end of an outer peripheral surface of the rod guide that is in contact with the inner peripheral surface of the cylinder is located closer to a second end of the rod than a lower end of a first inner peripheral surface of the rod guide where the outer peripheral surface of the rod is slidable. An upper end of an outer peripheral surface of the piston is located closer to the second end of the rod than an upper end of the insertion hole.