Optical Refraction Fuel Sensor for LP Warning
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Solution Overview
Problem
Conventional low fuel warning systems for liquid propane (LP) engine-powered vehicles, such as forklifts, fail to provide adequate warning time due to reliance on vapor pressure, which is affected by temperature, leading to unexpected engine stalls and increased downtime, especially in cold weather, and are prone to reliability issues with moving parts and high costs for visible fuel level sensors during tank exchanges.
Innovation Solution
A low fuel warning system that includes a fuel sensor configured to detect the liquid phase of LP in the fuel line, using an optic refraction sensor with a processor to monitor the fuel state and provide a reliable warning, independent of vapor pressure, and an auxiliary fuel tank system to extend warning time, ensuring the operator is alerted before the engine runs out of fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pressure switch based low LP fuel warning system is used, then the warning system is simple to implement, but the warning time is insufficient and the system fails in cold weather conditions
Solution Approach 1:
The patent replaces the mechanical pressure switch with an optical sensor system that detects fuel level directly without relying on vapor pressure. The optical sensor uses a light source and photodetector to detect the presence or absence of liquid fuel, eliminating the temperature-dependent mechanical pressure switch mechanism.
Solution Approach 2:
The patent changes the detection parameter from vapor pressure (which varies with temperature) to direct optical detection of liquid fuel level. This parameter change makes the warning system independent of temperature variations and provides reliable operation across all weather conditions.
2Loss of information
If a visible fuel level sensor gauge is used during tank exchanges, then the operator can see fuel level, but the cost increases and reliability decreases due to additional electrical connections
Solution Approach 1:
The patent extracts the fuel level detection function from the tank exchange process itself. The optical sensor is integrated into the fuel system and continuously monitors fuel level, providing warning information without requiring visible gauges on exchangeable tanks. This eliminates the need for additional electrical connections on temporary tank assemblies.
3Device complexity
If conventional vapor pressure based warning systems are used, then the system is simple to implement, but the warning comes on too late causing engine stalls and downtime
Solution Approach 1:
The patent implements preliminary detection by monitoring liquid fuel level directly before the vapor level drops critically low. The optical sensor detects the liquid fuel boundary early in the depletion process, providing advance warning that allows the operator to refuel before the engine stalls from vapor exhaustion.
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 system provides a more reliable and timely low fuel warning, reducing downtime and fuel costs by ensuring operators have sufficient time to refuel, even in cold conditions, and minimizing the need for premature fuel tank exchanges.
Implementation Method 1
using an optic refraction sensor with a processor to monitor the fuel state
Data Source
AI summary
The low fuel warning system includes a fuel line configured to transport fuel between an inlet port and an outlet port and a reservoir located intermediate to the inlet port and the outlet port, wherein the reservoir is configured to collect the fuel in a liquid state. The low fuel warning system further includes a fuel sensor located adjacent the reservoir and configured to detect the liquid state of the fuel and a processor in communication with the fuel sensor. The processor is configured to monitor a low fuel condition in the fuel line according to information received from the fuel sensor.