Sewing Machine Needle Bar Switching Mechanism for Noise Reduction
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Solution Overview
Problem
Sewing machines generate noise and vibration due to contact between the needle bar and a contact member at the top dead point, even when the needle bar is connected to the drive source and moving up and down.
Innovation Solution
A sewing machine with a switching mechanism that positions a contact member to either not contact or contact the needle bar based on the machine's operational state, preventing contact when the needle bar is connected to the drive source and moving up and down, and allowing contact during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the contact member is positioned to contact the needle bar at the top dead point, then the needle bar positioning accuracy is improved, but noise and vibration are generated during normal operation
Solution Approach 1:
The contact member is made movable between a first position (where it contacts the needle bar) and a second position (where it does not contact the needle bar). The switching mechanism dynamically adjusts the contact member's position based on the operational state: during normal operation, it is positioned to avoid contact and prevent noise/vibration, while during threading operations, it is positioned to contact the needle bar for accurate positioning.
Solution Approach 2:
The position parameter of the contact member is changed based on operational conditions. The switching mechanism alters the contact member's location between two distinct positions, changing the contact parameter from engaged to disengaged state, thereby controlling when positioning function is active and when noise prevention is prioritized.
2Reliability
If the contact member constantly contacts the needle bar, then positioning function is maintained, but noise and vibration occur during connected operation
Solution Approach 1:
The contact member transitions from a static contact position to a dynamic, adjustable position. During connected operation, the switching mechanism moves the contact member to a position where it does not interfere with the needle bar's reciprocating motion, eliminating noise and vibration while maintaining positioning capability when needed during threading operations.
3Device complexity
If a fixed contact member position is used, then the structure is simple, but it cannot prevent contact during connected operation
Solution Approach 1:
The contact member is equipped with a switching mechanism that allows it to move between positions. This dynamic capability, achieved through mechanisms like cam followers, eccentric mechanisms, or linkage systems driven by the existing drive shaft, enables the contact member to avoid contact during connected operation while maintaining structural simplicity through the use of conventional mechanical elements.
Data Source
AI summary
A sewing machine includes a needle bar, a needle bar release mechanism, a drive portion, a contact member, and a switching mechanism. The needle bar is configured to move up and down. The needle bar release mechanism is configured to connect and disconnect the transmission of the driving force between the drive shaft and the needle bar. The drive portion is configured to drive the needle bar release mechanism. The contact member is configured to come into contact with the needle bar in a case where the needle bar is positioned at a top dead point of the range within which the needle bar is able to move up and down. The switching mechanism is configured to switch the position of the contact member between a first position and a second position.