Marine Propeller Unit with Dual Driving Force Transmission
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Solution Overview
Problem
The propeller units for marine vessel propulsion devices generate loud impact noises when traveling through rocky reef regions due to repeated collisions with rocks, and existing solutions struggle to balance shift shock reduction and driving force transmission without causing damper rupture or slipping.
Innovation Solution
A propeller unit design featuring a first driving force transmitting member made of a soft elastic material to absorb shift shock and a second driving force transmitting member that engages only when the driving force exceeds a reference level, allowing for reliable transmission of the propeller shaft's force to the outer cylinder without overloading the first member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the damper is made soft to reduce shift shock, then shift shock is alleviated, but the damper cannot reliably transmit driving force without rupture or slipping
Solution Approach 1:
The patent divides the driving force transmission system into two separate members: a first driving force transmitting member (soft damper) and a second driving force transmitting member (harder material). This segmentation allows each member to have optimized properties for its specific function, resolving the contradiction between softness for shock absorption and hardness for reliable force transmission.
Solution Approach 2:
The patent changes the material parameter (hardness) between the two driving force transmitting members. The first member uses softer material for shock absorption during shift operations, while the second member uses harder material for reliable driving force transmission during normal operation, thereby resolving the contradiction through parameter differentiation.
2Reliability
If the damper is made hard to transmit driving force reliably, then driving force transmission is improved, but shift shock cannot be effectively reduced
Solution Approach 1:
The patent segments the transmission path into two distinct members with different material properties. The soft first member handles shift shock absorption, while the hard second member ensures reliable driving force transmission, eliminating the need to compromise between these conflicting requirements.
Solution Approach 2:
The first driving force transmitting member (soft damper) acts as an intermediary between the engine and the second driving force transmitting member. It mediates the shock during shift operations while allowing the second member to maintain its hardness for reliable force transmission, thus resolving the contradiction through intermediary buffering.
3Device complexity
If a single member transmits both shift shock and driving force, then device complexity is reduced, but the member undergoes rupture or slipping under conflicting demands
Solution Approach 1:
The patent divides the single transmission member into two separate members: a first driving force transmitting member and a second driving force transmitting member. This segmentation prevents rupture and slipping by assigning different functional roles to each member, with the first member handling shock absorption and the second member handling reliable force transmission.
Solution Approach 2:
The patent effectively creates a composite transmission system using two different materials with complementary properties. The softer material of the first member and the harder material of the second member work together as a composite system, providing both shock absorption and reliable force transmission without the need for a single complex material.
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 design effectively reduces shift shock and impact noise by allowing the soft damper to absorb lower forces and the harder second member to transmit higher forces, preventing damper breakage and ensuring reliable power transmission.
Implementation Method 1
a first driving force transmitting member including a cylindrical elastic member arranged between the inner cylinder and the outer cylinder
Implementation Method 2
a second driving force transmitting member arranged between the inner cylinder or the propeller shaft and the outer cylinder
Data Source
AI summary
A propeller unit for a marine vessel propulsion device includes an inner cylinder arranged to be fixed to the propeller shaft, an outer cylinder, a first driving force transmitting member, and a second driving force transmitting member. The propeller unit for marine vessel propulsion device further includes a pair of first engaging portions, and a pair of second engaging portions provided on the outer cylinder and the second driving force transmitting member. The pair of second engaging portions are arranged such that the mutual engaging of the respective second engaging portions is disengaged when a driving force is not transmitted to the propeller shaft and are arranged such that the respective second engaging portions become mutually engaged in a driving force transmittable manner by elastic deformation of the first driving force transmitting member when a driving force that is not less than a reference driving force is transmitted to the propeller shaft.