Variable Pitch Propeller Friction Lock Assembly
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Solution Overview
Problem
Existing variable pitch boat propellers face issues with loosening of threaded securing means due to vibrations, making installation and removal difficult and prone to component disassembly or damage, and often require complex disassembly of bolts and nuts.
Innovation Solution
A variable pitch boat propeller design that uses retaining means, including elastic elements and abutting surfaces, to keep components assembled, eliminating the need for screws, bolts, or other threaded securing means, and ensuring the lock nut remains coupled with the external cylindrical body during installation and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If threaded securing means (bolts, screws) are used to assemble the external cylindrical body parts and secure them to the internal cylindrical body, then the structural integrity and strength are improved, but the reliability deteriorates due to loosening from vibrations during operation
Solution Approach 1:
The patent replaces the threaded mechanical securing system (bolts, screws, nuts) with a friction-based mechanical interference system. The external cylindrical body parts are secured to the internal cylindrical body through friction engagement between complementary tapered surfaces, eliminating threaded fasteners that are prone to vibration-induced loosening. This substitution maintains structural integrity while significantly improving reliability by removing the loosening mechanism entirely.
2Stability of the object's composition
If multiple threaded securing means are used to assemble the propeller components, then the strength and stability of the assembly are improved, but the ease of operation deteriorates due to the complexity of installation and removal
Solution Approach 1:
The patent replaces the multi-bolt threaded fastening system with a friction-based tapered interface system. Instead of requiring multiple bolts to be tightened and loosened, the external cylindrical body parts are assembled by simply pushing them together along the axis, allowing the friction engagement to automatically secure them. This dramatically simplifies installation and removal operations while maintaining assembly stability through the friction lock.
3Reliability
If a lock nut is used to secure the internal cylindrical body to the motor shaft, then the reliability of the connection is improved, but the ease of operation deteriorates due to the difficulty of tightening and loosening the lock nut
Solution Approach 1:
The patent replaces the lock nut threaded fastening system with a friction-based tapered interface between the internal cylindrical body and the motor shaft. The internal cylindrical body is secured by pushing it onto the motor shaft, where friction engagement through complementary tapered surfaces provides a secure connection without requiring a lock nut. This eliminates the difficult tightening and loosening operations while maintaining connection security.
4Manufacturing precision
If threaded securing means are used to assemble the propeller components, then the manufacturing precision and structural integrity are improved, but the device complexity increases due to the large number of parts and assembly steps
Solution Approach 1:
The patent replaces the complex multi-component threaded fastening system with a simplified friction-based tapered interface system. Instead of multiple bolts, nuts, and washers, the design uses complementary tapered surfaces that engage through friction. This dramatically reduces the number of parts and assembly steps while maintaining manufacturing precision through the precise tapered geometry that ensures proper alignment and secure engagement.
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 simplifies and secures the installation and removal of the propeller, preventing component damage and disassembly risks, allowing for easy reinstallation and reducing the complexity of maintenance operations.
Implementation Method 1
at least one elastic element positioned between the internal cylindrical body and the external cylindrical body... which acts as a retaining means of the external cylindrical body with respect to the internal cylindrical body
Data Source
Figure 1
Figure 2
AI summary
There is described a variable pitch boat propeller, comprising at least one internal cylindrical body and at least one blade pivoted to an external cylindrical body of the propeller constituted by one or more juxtaposed parts, and coaxial to the internal cylindrical body which is in turn fitted coaxially to a motor shaft and constrained thereto by means of a nut. The propeller also comprises retaining means, which cooperate with the internal cylindrical body of the propeller, to keep in assembled position, with interlocking, at least the internal cylindrical body, the external cylindrical body and the blades. The propeller is characterized in that it comprises means to constrain by coupling the nut, which allows the propeller to be constrained to the motor shaft, to the external cylindrical body of the propeller, or with at least a part thereof.