Propeller Torque Device with Helical Threads
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Solution Overview
Problem
Current marine propeller torque transmitting devices fail to effectively absorb a greater degree of relative rotation between the propeller and its shaft, particularly during sudden shifts in rotational speed, limiting their shock absorption capabilities.
Innovation Solution
A propeller torque transmitting device comprising an adapter with internal axial splines and a coupler with external axial and helical threads, along with coaxial helical springs, is designed to be assembled as a module, allowing for significant axial movement and rotation to absorb shock loads, featuring a compact preassembled unit that can be easily attached to both the propeller and propeller shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional propeller mounting devices are used, then the propeller can be attached to the propeller shaft, but the device fails to effectively absorb a greater degree of relative rotation between the propeller and shaft during sudden shifts in rotational speed
Solution Approach 1:
The coupler is designed with dynamic freedom to rotate relative to the adapter through a defined range (up to 180 degrees in each direction). This relative rotation capability allows the device to adapt to sudden changes in rotational speed between the propeller and propeller shaft, converting rotational shocks into axial spring compression while maintaining operational reliability.
Solution Approach 2:
The resilient device utilizes spring compression as a parameter change mechanism to absorb shock energy. When relative rotation occurs between the propeller and shaft, the coupler rotates relative to the adapter, compressing the spring axially. This transforms rotational kinetic energy into elastic potential energy, significantly expanding the device's ability to handle rotational discrepancies while maintaining reliable operation.
2Ease of operation
If a module design with preassembled components is implemented, then ease of assembly is improved, but the device must still accommodate significant axial movement and rotation for shock absorption
Solution Approach 1:
The adapter, coupler, and resilient device are preassembled as an integrated module before installation onto the propeller and propeller shaft. This merging of components simplifies the assembly process, as the entire shock-absorbing mechanism can be installed as a single unit. Internally, the module maintains the necessary complexity with the coupler's rotational freedom and spring compression capability to handle significant axial movement and rotation for shock absorption.
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 device achieves enhanced shock absorption by allowing up to 180 degrees of relative rotation in each direction, utilizing helical springs for axial compression, reducing radial space requirements, and facilitating a compact module design that can handle significant rotational discrepancies, thus protecting marine propulsion systems from damage.
Implementation Method 1
a resilient device, 31 and 32, shaped to urge the coupler toward a preselected position
Implementation Method 2
utilizing helical springs for axial compression
Implementation Method 3
The one or more internal helical threads of the coupler and the one or more external helical threads of the adapter are configured to mesh with each other to cause relative axial movement between the coupler and the adapter in response to relative rotational movement
Data Source
AI summary
A shock absorber for a marine propulsion device is configured to provide an adapter, coupler and resilient device which can be assembled into a unit, or module, that can be inserted into a propeller. The resilient device includes two helical springs that urge the coupler into a central position with respect to the adapter and resist relative axial motion between the adapter and coupler. The shock absorber is intended to absorb the forces which occur during a shift from neutral to forward gear of the marine propulsion device.