Drum Strainer Cam Mechanism for Stable Snare Positioning
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Solution Overview
Problem
Existing strainer devices for drums require complex configurations with separate members like lock pins and springs to maintain the ON and OFF positions of the snare wire, which complicates the mechanism and can lead to unintentional position changes during transport.
Innovation Solution
A strainer device with a fixing portion, a rotatable operation portion, a movable portion, a cam portion with a cam surface, and a follower that uses a torsion spring to maintain the snare wire's position through a cam mechanism, allowing stable ON and OFF states without the need for additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate members such as lock pin and spring are provided to hold the snare wire at ON and OFF positions, then the snare wire position can be maintained, but the mechanism configuration becomes complex
Solution Approach 1:
The patent combines the lock pin and spring into a single integrated member. The lock pin is configured with an elastic portion that functions as the spring, eliminating the need for separate components. This integrated member is rotatably coupled to the movable portion and can simultaneously provide both the locking function (through the lock pin extending into the concave portion) and the elastic restoring force (through the elastic portion), thereby maintaining the snare wire position while simplifying the mechanism configuration
Solution Approach 2:
The integrated lock pin member performs multiple functions: it acts as both the locking element (lock pin) and the elastic restoring element (spring). The member can be rotated to extend the lock pin into the concave portion for positioning, and the elastic portion provides the necessary spring force. This multi-functional design reduces the number of components while maintaining the required functionality for holding the snare wire at designated positions
2Ease of operation
If the drum is turned upside down during transport, then the drum can be carried conveniently, but the lever rotates by its own weight causing unintentional position change of the snare wire
Solution Approach 1:
The patent applies preliminary anti-action by designing the mechanism to counteract the harmful effect of gravitational force on the lever before the problem occurs. The elastic portion of the integrated lock pin member is pre-loaded to provide a restoring force that opposes any unintended rotation of the lever. Additionally, the cam mechanism is designed with a cam surface and follower that create a mechanical interlock, preventing the lever from rotating freely under its own weight when the drum is transported in any orientation, thus maintaining the snare wire position stability during convenient drum carrying
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 solution allows for stable maintenance of the snare wire's ON and OFF states with a simple configuration, improving operability and preventing unintended position changes during transport.
Implementation Method 1
a pressing member; a cam portion including a cam surface provided on one of the movable portion or the operation portion; and a follower provided on the other of the movable portion or the operation portion, and configured to be relatively displaced with respect to the cam portion between a first position and a second position in the cam portion in accordance with the rotation of the operation portion while the pressing member is pressing against the cam surface of the cam portion
Data Source
AI summary
A strainer device for a drum includes a fixing portion attachable to a shell of the drum, an operation portion, a movable portion moved with respect to the fixing portion to change a snare wire between an ON state and an OFF state, a pressing member, a cam portion including a cam surface, and a follower configured to be relatively displaced with respect to the cam portion between a first position and a second position in the cam portion while the pressing member is pressing against the cam surface. A direction of a force acting on the follower with respect to the cam portion is directed to: a side of the first position within the cam portion in a state where the follower is disposed in the first position, and a side of the second position in a state where the follower is disposed in the second position.