Sewing Machine Auxiliary Motor Control for Fabric Feeding
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Solution Overview
Problem
Existing sewing machines lack the ability to independently control the speed and rotation direction of the lower drive wheel and upper roller, as well as the oscillation period of the needle-holding rod, which limits their performance with thick or curved materials, leading to potential fabric deformation or curling.
Innovation Solution
The sewing machine incorporates an auxiliary step-by-step motor connected to the drive wheel and roller, an encoder to detect the cam motion, and an auxiliary electronic board that adjusts the motor steps and rotation speed based on the encoder data, allowing for independent control of operating parameters and automatic reverse stitching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the lower drive wheel and upper roller are mechanically connected to the same motor, then the structure is simple, but the speed and rotation direction cannot be independently controlled
Solution Approach 1:
The patent divides the drive system into two independent motor units: a main motor for the drive wheel and an auxiliary motor for the roller. This segmentation allows each component to be controlled independently, enabling separate adjustment of speed and rotation direction for the drive wheel and roller, which is essential for processing thick or curved materials without deformation.
Solution Approach 2:
The system transitions from a fixed mechanical connection to a dynamic, independently controllable system. The auxiliary motor can be activated or deactivated based on the sewing operation requirements, and its speed can be dynamically adjusted through electronic control, allowing the roller to adapt its rotation independently from the drive wheel.
2Device complexity
If the oscillation period of the needle-holding rod is mechanically determined by the drive wheel speed, then the control is simple, but the oscillation period cannot be independently modulated
Solution Approach 1:
The patent employs an encoder that detects the rotational position of the cam and provides feedback signals to the auxiliary electronic board. This feedback mechanism enables precise measurement of the cam's rotational angle, allowing the system to accurately control and modulate the oscillation period of the needle-holding rod independently from the drive wheel speed, ensuring precise stitch length control.
Solution Approach 2:
The system replaces purely mechanical control with an electromechanical control system. The auxiliary motor, encoder, and auxiliary electronic board create an electronic control loop that substitutes for traditional mechanical linkages, enabling independent and precise control of the needle-holding rod's oscillation period through electronic signals rather than mechanical constraints.
3Ease of operation
If the roller speed is tied to the drive wheel speed, then the system is simple to operate, but the fabric feeding cannot be optimized for different material types
Solution Approach 1:
The roller is equipped with an auxiliary motor that can be independently controlled, transforming it from a passive component driven mechanically to an active component with independent speed and direction control. This dynamic capability allows the roller speed to be optimized for different fabric types and sewing operations while maintaining simple operation through electronic control interfaces.
Solution Approach 2:
The system enables independent adjustment of the roller's rotational speed parameter through the auxiliary motor and electronic control board. This parameter change capability allows optimization of fabric feeding speed for different material thicknesses and types, improving adaptability while the control keyboard maintains ease of operation.
4Device complexity
If reverse stitching is achieved by mechanical connection reversal, then the mechanism is simple, but the rotation direction reversal is not precise or flexible
Solution Approach 1:
The patent replaces mechanical reversal mechanisms with electronic control for direction reversal. The auxiliary motor's rotation direction is controlled electronically through the auxiliary electronic board, which can precisely command the motor to rotate in either direction based on the sewing operation requirements, providing flexible and precise rotation direction control without complex mechanical reversal linkages.
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 solution enables precise control over fabric feeding speed and stitch length, preventing deformation and enabling smooth operation with thick or curved materials by allowing independent modulation of wheel and roller speeds and reversing the rotation direction as needed.
Implementation Method 1
an encoder, mechanically connected to said cam for the oscillation of said needle-holding rod in order to detect the motion of said cam itself
Implementation Method 2
at least one further auxiliary motor, preferably of the step-by-step type, mechanically connected, through transmission members, to said lower drive wheel and to said upper foot roller in order to set them rotating
Data Source
Figure 1
AI summary
The invention is a sewing machine (1) comprising a main motor (8) suited to axially rotate a main shaft (3) for moving the vertical needle-holding rod (4), an auxiliary motor (9) mechanically connected to the lower drive wheel (6) and to the roller (71) of the upper presser foot (7), an encoder (10) connected to a cam (43) for the oscillation of the needle-holding rod (4) and suited to detect the motion of said cam (43), that is, of said rod (4), an auxiliary electronic board (11) communicating with said encoder (10) and with said auxiliary motor (9), and wherein said auxiliary electronic board (11) activates said auxiliary motor (9) so as to modulate the speed and/or the rotation direction of said lower drive wheel (6) and of said upper roller (71) according to the motion of said needle-holding rod (4).