CNG Fill Hose Interlock for Drive-Off Accident Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing safety systems for filling compressed natural gas vehicles do not adequately prevent drive-off accidents, which can lead to catastrophic gas leaks and explosions due to the high pressure of natural gas, as they are not applicable to the unique hazards of compressed natural gas and do not provide redundant safety measures.
Innovation Solution
A multiply-redundant system using multiple electrical proximity sensors and mechanical microswitches to lock out the vehicle's ignition or disable it if the high-pressure gas fill system is not correctly disconnected, combined with optional mechanical and electrical override mechanisms to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing safety systems are used for filling compressed natural gas vehicles, then the filling process can be completed, but drive-off accidents can occur leading to catastrophic gas leaks and explosions
Solution Approach 1:
The system performs preliminary detection of the filling hose connection status before allowing the vehicle to start or move. Multiple sensors (electrical proximity sensors and mechanical microswitches) check whether the filling hose is properly disconnected, and the ignition is locked out until the safe state is confirmed, preventing drive-off accidents before they can occur.
Solution Approach 2:
The system implements redundant safety measures with multiple independent sensors (electrical proximity sensors and mechanical microswitches) that detect filling hose connection status. This redundancy provides a backup detection mechanism to ensure accurate identification of the filling state, preventing false readings that could lead to unsafe vehicle operation.
2Measurement precision
If multiple sensors and microswitches are used to detect filling hose connection, then detection accuracy improves, but system complexity increases
Solution Approach 1:
The system uses an intermediary control unit that receives signals from multiple independent sensors (electrical proximity sensors and mechanical microswitches) and processes them to determine the filling hose connection status. This intermediary component coordinates the inputs from various sensors and generates the appropriate ignition lockout signal, managing system complexity through centralized control logic.
Solution Approach 2:
The system combines electrical proximity sensors with mechanical microswitches to detect filling hose connection status. The electrical sensors provide non-contact detection capability, reducing mechanical wear, while the mechanical microswitches provide redundant verification. This hybrid approach balances measurement precision with manageable system complexity.
3Reliability
If the ignition is locked out when filling hose is attached, then safety is improved, but ease of operation decreases
Solution Approach 1:
The system continuously monitors the filling hose connection status through multiple sensors and provides feedback to the ignition control system. When the filling hose is properly disconnected, the sensors generate a safe state signal that automatically enables vehicle operation. This feedback mechanism ensures safety without requiring manual intervention, maintaining ease of operation after the filling process is complete.
Data Source
AI summary
A multiply-redundant system that prevents a driver from starting and/or moving a vehicle if a compressed natural gas fill system is not correctly and completely disconnected from the vehicle. One or more sensors in combination with one or more optional microswitches combine to lock-out the vehicle's ignition or otherwise prevent it from starting and/or moving. For different levels of safety, different combinations of sensors can be used with the lowest level having a single proximity sensor sensing the presence or absence of a high-pressure fill hose. The highest level of safety being achieved by having separate proximity sensors on the fuel fill hose fitting, the gas cap cover and a manual safety valve along with a redundant microswitch. An optional override that may be restricted as to the number of times it can be used can allow starting with a faulty sensor in order to allow maintenance.