Needle Bar Driving System Torque Balancing
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Solution Overview
Problem
Conventional sewing machines experience vibrations and noise due to unbalanced needle bar driving systems, particularly at high speeds, leading to instability and reduced accuracy, and existing solutions either fail to adequately reduce vibrations or introduce unbalance issues.
Innovation Solution
A reciprocating linear counterbalance system is implemented, where a counterweight piston moves oppositely to the needle bar, ensuring equal but opposite torques on the armshaft, eliminating horizontal unbalance and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an asymmetric counterbalance weight is used to compensate vertical inertia forces, then vibration reduction is achieved at low to medium speeds, but horizontal unbalance develops causing strong vibrations at high speeds
Solution Approach 1:
The patent applies counterweight principles by introducing a dedicated counterbalance mechanism with counterbalance arms and counterweights that rotate in opposition to the needle bar driving forces. This creates opposing inertial forces that cancel out both vertical and horizontal vibration components, enabling high-speed operation without the horizontal unbalance problems of conventional asymmetric counterbalance designs
Solution Approach 2:
The patent segments the counterbalance function into separate components: the armshaft with crank mechanism for needle bar driving, and a separate counterbalance shaft with counterbalance arms and weights for vibration compensation. This segmentation allows independent optimization of each function and enables effective cancellation of both vertical and horizontal vibration forces
2Ease of manufacture
If conventional asymmetric counterbalance designs are used, then manufacturing simplicity is maintained, but vibration and noise increase at high speeds
Solution Approach 1:
The patent uses counterweight mechanisms with counterbalance arms and weights that generate opposing forces to cancel vibration-induced noise. The counterweights are positioned and sized to create inertial forces that counteract the forces generated by the needle bar and presser foot, significantly reducing operational noise
3Stability of the object's composition
If a rigid heavy housing is used to resist vibration forces, then stability is provided, but machine weight increases and design becomes less adaptable
Solution Approach 1:
The patent employs counterbalance mechanisms that actively cancel vibration forces before they can affect housing stability. By using counterweights on the counterbalance shaft to generate opposing inertial forces, the system eliminates the need for heavy rigid housings, achieving stability through dynamic balancing rather than static mass
Solution Approach 2:
Instead of using a heavy housing to resist vibration forces passively, the patent inverts the approach by using active counterbalancing mechanisms that generate forces to cancel vibrations. This transforms the solution from passive resistance through mass to active cancellation through dynamic forces
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 achieves a well-balanced system that reduces noise, enables higher speed operation, and allows for a lighter design by eliminating vibrations and maintaining stability.
Implementation Method 1
a counterweight piston driven by the counterweight driving assembly, the counterweight piston performs also a reciprocating linear guided movement along an axis parallel to said axis
Implementation Method 2
the combined torque of the counterweight piston and the counterweight driving assembly acting on the armshaft is substantially equal to the combined torque of the needle bar and the needle bar driving assembly acting also on the armshaft, but these two torques have opposite direction
Data Source
AI summary
Improved needle bar driving system for sewing machines, that comprises an armshaft rotating with a predetermined speed; a needle bar driving assembly driven by the armshaft and has a needle bar that performs a reciprocating guided linear movement along a substantially vertical axis; a counterweight driving assembly is driven by the armshaft; and a counterweight piston driven by the counterweight driving assembly, and the counterweight piston also performs a reciprocating linear guided movement along an axis parallel to the axis, wherein the movements of the counterweight driving assembly and of the counterweight piston are always opposite to the movement of the needle bar driving assembly and of the needle bar, wherein the combined torque of the counterweight piston and the counterweight driving assembly acting on the armshaft is substantially equal to the combined torque of the needle bar and needle bar driving assembly acting also on the armshaft, but the two torques have opposite direction, whereby the armshaft gets substantially balanced.