Dual Bimetal Current Interruption for EV Load Overheating
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Solution Overview
Problem
Existing vehicle safety devices fail to reliably interrupt current supply to a load when an abnormality occurs, as the current can be resumed even after initial interruption.
Innovation Solution
A vehicle safety device with a first bimetal switch that interrupts the current when the load reaches a first set temperature and a second bimetal switch that ensures the supply line remains interrupted at a higher second set temperature, preventing re-energization, is implemented in hybrid or electric vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control means open the switch on the basis of signal from temperature detecting means, then current interruption is achieved, but reliability of current interruption deteriorates because current may be resumed when abnormality occurs in control means
Solution Approach 1:
The interrupting mechanism is divided into two independent segments: a first interrupting mechanism that interrupts current when temperature reaches a first set temperature, and a second interrupting mechanism that interrupts current when temperature reaches a second set temperature (higher than the first). This segmentation ensures that if one mechanism fails due to abnormality, the other can still perform current interruption, thereby improving reliability without requiring a single complex mechanism.
Solution Approach 2:
The second interrupting mechanism is designed to operate at a higher temperature threshold as a preliminary safety measure. When the first interrupting mechanism fails to interrupt current due to control means abnormality, the second mechanism provides a backup interruption capability at an elevated temperature, preventing catastrophic failure before it occurs.
2Reliability
If single interrupting mechanism is used, then device complexity is reduced, but reliability deteriorates because current may be resumed after interruption when abnormality occurs
Solution Approach 1:
The two interrupting mechanisms are differentiated by their operating temperature parameters. The first mechanism operates at a lower temperature threshold while the second operates at a higher temperature threshold. This parameter differentiation allows the system to maintain reliability through multiple mechanisms while keeping each individual mechanism relatively simple and well-defined.
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 enhances the reliability of current interruption by ensuring that the supply line cannot be returned to an energized condition even if an abnormality occurs, thereby maintaining safety and preventing overheating.
Implementation Method 1
first bimetal switch that interrupts the current when the load reaches a first set temperature
Implementation Method 2
second bimetal switch that ensures the supply line remains interrupted at a higher second set temperature
Data Source
AI summary
A vehicle safety device installed in a hybrid electric vehicle or an electric vehicle is provided to be capable of interrupting a current supplied from a power supply to a load via a supply line. The vehicle safety device includes first interrupting mechanism adapted to set the supply line in an interrupted condition when a temperature of the load reaches a first set temperature and second interrupting mechanism adapted to set the supply line in the interrupted condition such that the supply line cannot be returned to an energized condition when the temperature of the load reaches a second set temperature that is higher than the first set temperature.