Interlock Circuit for Motor Vehicle Power Source
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Solution Overview
Problem
Conventional electric power sources for motor vehicles fail to accurately detect the disconnected state of an interlock wire, leading to incorrect judgments about the interlock circuit failure and short-circuit conditions, resulting in inappropriate shutdowns of the contactor and potential safety hazards.
Innovation Solution
The electric power source incorporates a unique interlock circuit with a current output circuit, a first and second current detection subcircuit, and a judgment circuit that uses detectable currents to accurately determine the disconnected state of the interlock wire, employing diodes to differentiate between connected and short-circuited states, and switching between current output subcircuits to ensure reliable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single current detection circuit is used to detect the interlock wire state, then the device complexity is reduced, but the measurement precision of the interlock wire disconnected state deteriorates
Solution Approach 1:
The current detection function is segmented into two separate detection circuits: a first current detection circuit that detects current flowing through the interlock wire, and a second current detection circuit that detects current flowing through a parallel path. This segmentation allows each circuit to independently monitor different current paths, enabling accurate distinction between disconnected state and short-circuit state without requiring a single complex detection system.
Solution Approach 2:
A judgment circuit is introduced as an intermediary that receives detection results from both current detection circuits and determines the actual state of the interlock wire. The judgment circuit analyzes the combination of detection signals to distinguish between true disconnection and short-circuit conditions, acting as a mediator that resolves the ambiguity that would exist with a single detection circuit.
2Object-affected harmful factors
If the interlock wire is short-circuited to ground or power circuit, then the contactor shutdown safety is improved, but the reliability of the interlock circuit deteriorates due to false judgments
Solution Approach 1:
The detection system is divided into two independent current detection circuits that monitor different current paths. The first circuit detects current through the interlock wire while the second circuit detects current through a parallel path. This segmentation enables the system to identify short-circuit conditions by comparing the presence or absence of current in each path, preventing false shutdown judgments while maintaining safety.
Solution Approach 2:
The judgment circuit continuously monitors the output signals from both current detection circuits and provides feedback control to the contactor. By analyzing the combined feedback from both detection paths, the system can accurately determine whether an interlock wire disconnection or short-circuit condition exists, ensuring appropriate contactor operation without false positives that would compromise reliability.
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 configuration allows for precise detection of the interlock wire's disconnected state and potential short-circuits, ensuring the contactor is correctly shut off, enhancing safety and preventing false judgments about interlock circuit failures.
Implementation Method 1
employing diodes to differentiate between connected and short-circuited states
Implementation Method 2
a first current detection subcircuit for detecting the detectable current which is outputted from the current output circuit; and a second current detection subcircuit
Data Source
AI summary
An electric power source for a motor vehicle is so constructed and arranged that an interlock circuit detects a disconnected state of an interlock wire and turns off a contactor. The interlock circuit includes: a current output circuit outputting a detectable current via a diode to the interlock wire; a first current detection subcircuit connected via the interlock wire and the diode to the current output circuit; a second current detection subcircuit connected to a connection point operatively located between the current output circuit and the diode; and a judgment circuit. In the interlock circuit, when the detectable current is detected at the second current detection subcircuit and when the detectable current is not detected at the first current detection subcircuit, the judgment circuit judges the interlock wire to be in a disconnected state and cuts off the contactor.