Asymmetrical Ring Varistor Layout for Welding Fracture Resistance
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Solution Overview
Problem
Existing ring varistors face issues with substrate rupture during welding due to thermal and mechanical shocks, which affects their installation and performance in DC micromotors.
Innovation Solution
A ring varistor design with asymmetrical electrode gaps and nonlinear volt-ampere characteristics, featuring non-orthogonal electrode gaps and asymmetrical electrode structures, is used to improve heat shock resistance and thermal conductivity uniformity, incorporating strontium titanate or zinc oxide substrates with specific electrode materials and a preparation process that includes doping and asymmetrical electrode printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If symmetrical electrode gaps are used in ring varistor, then manufacturing process is simple, but welding fracture resistance is poor
Solution Approach 1:
The patent applies asymmetry principle by designing electrode gaps with non-uniform widths and non-orthogonal arrangements. Specifically, adjacent electrode gaps have different widths, and the straight edges of electrodes are not parallel to form non-orthogonal gaps. This asymmetric structure creates more uniform stress distribution during welding, preventing substrate rupture while maintaining manufacturing feasibility through screen printing processes.
2Productivity
If higher welding temperature is used to improve welding efficiency, then productivity increases, but substrate rupture risk increases
Solution Approach 1:
The patent changes the geometric parameters of electrode gaps (width, orientation, shape) to modify thermal stress distribution. The non-orthogonal and asymmetric gap designs alter heat flow patterns during welding, reducing thermal concentration at critical substrate points. This allows higher welding temperatures to be used without increasing substrate rupture risk, thereby improving productivity while maintaining reliability.
3Reliability
If electrode gaps are made larger to reduce thermal stress, then heat shock resistance improves, but electrical performance deteriorates
Solution Approach 1:
The patent applies local quality principle by creating electrode gaps with varying widths in different locations. Some gaps are larger to provide thermal stress relief and improve heat shock resistance, while other gaps are smaller to maintain electrical performance. The asymmetric design allows optimization of each gap's dimensions based on local thermal and electrical requirements, achieving both heat shock resistance and electrical performance simultaneously.
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 reduces welding fractures and enhances heat shock resistance, improving the varistor's ability to withstand thermal and mechanical stresses, while maintaining electrical performance and increasing capacitance for better electromagnetic interference suppression.
Implementation Method 1
the glass slurry melts, wets the ring resistor body and penetrates into the ring resistor body, to form a canine-like mating state, thereby forming a mechanical interlocking connection
Implementation Method 2
A ring varistor design with asymmetrical electrode gaps and nonlinear volt-ampere characteristics, featuring non-orthogonal electrode gaps and asymmetrical electrode structures, is used to improve heat shock resistance and thermal conductivity uniformity
Implementation Method 3
The voltage sensitivity characteristic can be used to absorb transient spark generated on the commutator to protect the motor brush and the winding
Implementation Method 4
The capacitive characteristic can be used to inhibit electromagnetic interference, prolong the working life of the micromotor, and improve the working quality of the micromotor
Data Source
AI summary
The present invention provides a ring varistor for use in DC micromotor including a ring varistor substrate having nonlinear volt-ampere characteristics and at least three independent electrodes evenly sintered on an end face of the ring varistor substrate. The electrode gap between two adjacent electrodes consists of two straight parallel edges of the two adjacent electrodes, and an inner and an outer concentric arc on the substrate ring, the electrode gap is not orthogonal to the ring. Due to the asymmetry arrangement of the surface electrodes and the electrode gaps, the electrode materials and the substrate materials with different thermal conductivity have no contact cross distribution with each other at the radial electrode gap. During welding, the heat shock is transmitted asymmetrically through the asymmetric electrodes, to improve the uniformity of the heat conduction distribution of the varistor and reduce the defective rate of the substrate welding fracture.