Sewing Machine Presser Foot Force Control via Feed Dog Synchronization
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Solution Overview
Problem
The mechanism for adjusting the pressing force applied to the presser foot of a sewing machine is complex and requires complicated operations to synchronize with the sewing machine motor, especially when accommodating changes in the thickness and hardness of the sewing object.
Innovation Solution
A sewing machine design that includes a presser spring, a restriction portion, and a change member to simplify the operation of adjusting the urging force applied to the presser foot by changing the distance between first and second members, allowing the transmission of the presser spring's force to be controlled in synchronization with the sewing machine motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanism is designed to change the pressing force applied to the presser foot in synchronization with the sewing machine motor rotation, then the sewing machine can accommodate changes in the thickness and hardness of the sewing object, but the mechanism becomes complex and the adjustment operation becomes complicated
Solution Approach 1:
The presser bar mechanism is divided into multiple segments: the presser bar itself, the adjustment portion that can move independently, and the restriction portion that controls force transmission. This segmentation allows each part to perform a specific function, simplifying the overall control mechanism while maintaining the ability to adapt pressing force to different sewing objects.
Solution Approach 2:
The adjustment portion is designed to move dynamically in the up-down direction based on the position of the feed dog. The restriction portion selectively restricts or allows transmission of urging force from the presser spring to the presser bar, creating a dynamic system that automatically adapts pressing force without complex manual adjustment mechanisms.
2Adaptability or versatility
If a mechanism is designed to change the pressing force applied to the presser foot in synchronization with the sewing machine motor rotation, then the sewing machine can accommodate changes in the thickness and hardness of the sewing object, but the adjustment operation becomes complicated
Solution Approach 1:
The adjustment portion automatically moves up and down in response to the feed dog position, and the restriction portion automatically restricts or allows force transmission based on this position. This self-service mechanism eliminates the need for complicated manual adjustment operations while maintaining adaptability to different sewing objects.
Solution Approach 2:
The system uses the position of the feed dog as feedback to control the movement of the adjustment portion and the restriction of force transmission. This feedback mechanism ensures that the pressing force is automatically adjusted in synchronization with the sewing machine motor rotation without requiring complex user intervention.
3Force
If the adjustment portion contacts with the presser bar holder to transmit urging force, then the presser foot applies sufficient pressing force to the sewing object, but the mechanism requires complex coordination to prevent contact at inappropriate times
Solution Approach 1:
The restriction portion acts as an intermediary between the presser spring and the presser bar. It selectively allows or restricts the transmission of urging force based on the position of the adjustment portion, which is determined by the feed dog position. This intermediary mechanism simplifies the coordination required to apply sufficient pressing force at the appropriate times.
4Adaptability or versatility
If the adjustment portion is spaced apart from the presser bar holder to prevent transmission of urging force, then the presser foot can accommodate thick or hard sewing objects, but the mechanism requires complex control to ensure proper spacing
Solution Approach 1:
The adjustment portion automatically moves to the appropriate position (contacting or spaced from the presser bar holder) in response to the feed dog position. This self-service behavior eliminates the need for complex control mechanisms to manage the spacing required for handling thick or hard sewing objects.
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 design simplifies the operation of adjusting the pressing force applied to the presser foot, making it easier to adapt to different sewing objects by controlling the transmission of urging force with a simple operation, enhancing the sewing machine's ability to handle both straight stitching and curved line sewing.
Implementation Method 1
The presser spring is configured to apply an elastic force to the presser bar in a downward direction via the adjustment portion and the presser bar holder
Implementation Method 2
The restriction portion is configured to restrict transmission of the elastic force from the presser spring to the presser bar when the restriction portion contacts with the adjustment portion
Data Source
AI summary
The sewing machine includes a sewing machine motor, a needle plate, a feed dog, a presser bar, a presser bar holder, an adjustment portion, a presser spring, a restriction portion, and a change member having a first member and a second member. In a first period in which a feed dog upper end is above a plate upper surface and the adjustment portion is spaced apart from the restriction portion, the adjustment portion contacts with the presser bar holder to cause the urging force of the presser spring to be transmitted to the presser bar. In a second period in which the feed dog upper end is beneath the plate upper surface and the adjustment portion contacts with the restriction portion, the adjustment portion is spaced apart from the presser bar holder to prevent the urging force of the presser spring from being transmitted to the presser bar.