Purge Pump and HC Sensor Cold Start Fuel Vapor Control
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Solution Overview
Problem
Conventional evaporative emissions (EVAP) control systems are ineffective during engine cold starts due to the lack of engine vacuum and unknown fuel vapor composition, leading to increased hydrocarbon (HC) emissions.
Innovation Solution
An EVAP control system and method utilizing a purge pump and HC sensor to deliver a desired amount of fuel vapor to the engine, controlled by a controller that detects imminent cold starts and adjusts the purge pump and purge valve operations based on measured HC levels, ensuring efficient HC vapor delivery and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine vacuum is used to deliver fuel vapor from the vapor canister to the engine, then the system structure is simple, but the system cannot deliver fuel vapor during cold starts when engine vacuum is insufficient
Solution Approach 1:
The purge pump is activated before the engine start (pre-crank period) to deliver fuel vapor to the engine in advance, ensuring adequate fuel vapor is available when the engine needs it during cold start conditions
Solution Approach 2:
The purge pump acts as an intermediary device that replaces the insufficient engine vacuum during cold starts, providing the necessary pressure differential to move fuel vapor from the canister to the engine when the natural vacuum mechanism fails
2Measurement precision
If fuel vapor composition is unknown, then the system operation is simple, but the control precision of fuel vapor delivery is poor leading to increased HC emissions
Solution Approach 1:
The HC sensor provides real-time feedback on the composition and concentration of fuel vapor in the vapor line, allowing the controller to adjust the purge pump operation and purge valve timing to deliver the optimal amount of fuel vapor during cold starts
Solution Approach 2:
The HC sensor replaces the need for complex mechanical composition analysis systems by using an electronic sensor to detect hydrocarbon concentration, providing precise measurement data to the controller for optimized fuel vapor delivery
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 effectively decreases HC emissions during cold starts by providing a controlled amount of fuel vapor, improving combustion and catalyst light-off, thereby reducing raw fuel exhaustion and emissions.
Implementation Method 1
a purge pump configured to pump fuel vapor trapped in a vapor canister to an engine of the vehicle via a vapor line
Implementation Method 2
a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump
Implementation Method 3
the fuel vapor resulting from evaporation of a liquid fuel stored in a fuel tank of the engine
Data Source
AI summary
An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor to an engine of the vehicle via a vapor line and a purge valve. The system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. A controller is configured to: detect an imminent cold start of the engine and, in response to the detecting, perform the cold start of the engine by controlling at least one of the purge pump and the purge valve, based on the measured amount of HC, to deliver a desired amount of fuel vapor to the engine, which decreases HC emissions by the engine.