Electronic Fuel Injection Feedback Control for Dragster Engines
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Solution Overview
Problem
Mechanical fuel injection systems for high-performance engines, such as dragsters, become inefficient beyond peak torque as they deliver excessive fuel at high speeds, leading to a rich air-to-fuel mixture and potential engine failure due to premature combustion.
Innovation Solution
An automated self-correcting electronic fuel injection system with a feedback control scheme that adjusts the air-to-fuel ratio using an electronic control unit (ECU) and a variable flow valve, optimizing fuel delivery based on engine speed and environmental parameters to maintain an operator-specified air-to-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical fuel injection is used to deliver fuel at high engine speeds, then fuel flow increases to support higher speeds, but excessive fuel is delivered causing a rich air-to-fuel mixture and potential engine failure
Solution Approach 1:
The electronic fuel injection system incorporates feedback control by monitoring actual fuel flow with a flow sensor and comparing it to the desired fuel flow calculated from air flow measurements and target air-to-fuel ratio. The ECU continuously adjusts the fuel injection duration based on this feedback to maintain the correct air-to-fuel mixture even at high engine speeds where mechanical systems would deliver excessive fuel.
Solution Approach 2:
The patent replaces the mechanical fuel injection system with an electronic fuel injection system that uses electronic sensors, microprocessors, and electronic actuators instead of mechanical linkages and purely mechanical flow control. This substitution enables precise electronic control of fuel delivery to match the non-linear relationship between engine speed and optimal fuel flow, preventing the rich mixture condition that occurs with mechanical systems at high speeds.
2Productivity
If mechanical fuel injection delivers fuel linearly proportional to engine rpm, then fuel flow is simple to control, but fuel efficiency decreases after peak torque due to excessive fuel delivery
Solution Approach 1:
The electronic fuel injection system implements dynamic fuel flow control where the fuel injection duration is continuously adjusted based on real-time engine operating conditions. The ECU calculates the desired fuel flow based on measured air flow and target air-to-fuel ratio, then dynamically modifies injection timing and duration to optimize fuel efficiency across the entire operating range, unlike fixed mechanical systems that cannot adapt to changing conditions.
Solution Approach 2:
The system changes the control parameter from simple engine rpm-based mechanical control to a complex multi-parameter electronic control system that considers air flow, target air-to-fuel ratio, and actual fuel flow measurements. This enables the system to optimize fuel efficiency by adjusting fuel delivery based on multiple varying parameters rather than a single linear relationship with engine speed.
3Reliability
If electronic fuel injection is implemented with feedback control, then air-to-fuel ratio is optimized across broad rpm range, but system complexity increases with multiple sensors and electronic components
Solution Approach 1:
The electronic fuel injection system implements self-service through automatic feedback control where the ECU continuously monitors fuel flow with a sensor, compares it to the desired flow calculated from air flow measurements, and automatically adjusts injection duration without manual intervention. This self-regulating mechanism ensures reliable air-to-fuel ratio control across the entire operating range, compensating for the increased system complexity through automation.
Data Source
AI summary
Electronic fuel injection for an internal combustion engine maintains an operator-specified air-to-fuel ratio during engine operations in high-speed, high-volume, mixed fuel applications. A microprocessor-based controller executes a program stored in memory to calculate a fuel flow value as a function of the specified air-to-fuel ratio and specified density ratio of mixed fuels. The controller outputs a control signal to a variable fuel flow relief valve and receives feedback from an engine fuel flow sensor. The controller adjusts the control signal until the feedback matches the fuel flow value. The program optimizes the fuel flow value by accounting for engine air flow, water vapor density, and dry air density effects in the calculation, based on signals received by the controller from various environmental sensors. The system has particular application in dragster engines that burn a mixture of nitromethane and methanol.