Hydrocarbon Sensor Canister Load Estimation
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Solution Overview
Problem
Existing methods for determining the load of a fuel vapor canister in vehicles, such as using exhaust gas sensors or temperature changes, are inadequate, especially in hybrid vehicles where engine operation is intermittent, leading to reduced fuel economy and inaccurate load estimation.
Innovation Solution
A method utilizing a three-way valve and a single hydrocarbon sensor to route purge, refueling, and breakthrough vapors through the sensor, allowing for accurate load estimation without engine operation, by measuring the amount of fuel vapors during these events and calculating the canister load based on sensor output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaust gas sensors are used to determine canister load, then load estimation is possible, but the engine must be operational and combusting purged fuel vapors, which reduces fuel economy in hybrid vehicles
Solution Approach 1:
A three-way valve is introduced as an intermediary component to route vapor flows (purge, refueling, breakthrough) through a single hydrocarbon sensor. This mediator enables the sensor to access canister load information without requiring engine operation or vapor combustion, thus maintaining measurement accuracy while preserving fuel economy in hybrid vehicles.
2Measurement precision
If canister temperature is monitored to estimate load, then load indication is obtained, but the temperature equalizes with ambient temperature over time, making the indicator unreliable when the engine is non-operational
Solution Approach 1:
The patent replaces the thermal-based measurement system (temperature monitoring) with a chemical-based measurement system (hydrocarbon sensor). This substitution eliminates the problem of temperature equalization with ambient conditions, providing reliable canister load indication regardless of how long the engine has been non-operational or parked.
3Measurement precision
If multiple sensors are used to measure purge, refueling, and breakthrough vapors, then accurate load determination is achieved, but hardware complexity and cost increase
Solution Approach 1:
A single hydrocarbon sensor is designed to perform multiple measurement functions by detecting different vapor flows (purge, refueling, and breakthrough vapors) routed through it by the three-way valve. This multi-functional approach maintains comprehensive canister load determination capability while reducing hardware complexity and cost compared to using multiple separate sensors.
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 approach enables accurate estimation of the fuel vapor canister load in hybrid vehicles without affecting fuel economy, using a single sensor to measure vapors during different operations, thereby improving emissions compliance and reducing hardware costs.
Implementation Method 1
routing each of a purge flow from a fuel vapor canister, a loading flow into the fuel vapor canister, and a breakthrough flow from the fuel vapor canister through a hydrocarbon sensor
Implementation Method 2
adjusting a three-way valve to a first position to flow purge vapors from a canister through a hydrocarbon sensor, adjusting the three-way valve to a second position to flow refueling vapors from a fuel tank into the canister via the hydrocarbon sensor
Implementation Method 3
The fuel vapors may be stored in the fuel vapor canister, which contains adsorbent material, such as activated carbon, capable of adsorbing hydrocarbon (HC) fuel vapor
Data Source
AI summary
Methods and systems are provided for determining a load of a canister included in an evaporative emissions system of a vehicle. One example method comprises flowing each of purge vapors, refueling vapors, and breakthrough vapors through a common hydrocarbon sensor and using output from the hydrocarbon sensor based on the flowing of different vapors to estimate the load of the canister.