Hybrid Vehicle Fuel Injection Control for Rapid Deceleration
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Solution Overview
Problem
In hybrid vehicles equipped with a forced induction device, rapid decreases in engine load lead to excessive fuel injection, resulting in an over-rich air-fuel ratio during rapid deceleration, which can cause emission deterioration and accidental fires due to the prolonged period of excessive fuel injection.
Innovation Solution
A controller is implemented to manage the intake air amount by setting upper and lower limits, controlling the forced induction device, throttle valve, and variable valve timing to reduce the intake air decrease, thereby minimizing the excessive fuel injection and maintaining an optimal air-fuel ratio. Additionally, the rotating electric machine absorbs excessive torque generated during rapid deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the amount of intake air is rapidly decreased during rapid deceleration in a hybrid vehicle with forced induction device, then the fuel pressure rapidly decreases, but the actual fuel pressure cannot decrease unless fuel is injected, resulting in excessive fuel injection amount and over-rich air-fuel ratio
Solution Approach 1:
The controller predicts the future fuel pressure based on the current decrease rate and sets the target fuel pressure in advance to match the predicted future pressure. This preliminary action allows the fuel injection system to prepare for the pressure decrease, preventing excessive fuel injection by aligning the injection amount with the anticipated fuel pressure state rather than reacting to the current state.
2Manufacturing precision
If the target fuel pressure is set to rapidly decrease to match the rapid decrease in intake air amount, then the fuel injection amount becomes excessive with respect to the optimum injection amount, resulting in over-rich air-fuel ratio
Solution Approach 1:
The controller predicts the future fuel pressure and sets the target fuel pressure in advance based on this prediction. By performing this preliminary action, the system anticipates the fuel pressure state and adjusts the target accordingly, preventing the mismatch that would otherwise cause excessive fuel injection and over-rich air-fuel ratio.
3Measurement precision
If the minimum injection amount is used to maintain injection accuracy during fuel pressure decrease, then the injection amount becomes excessive with respect to the optimum injection amount, leading to deterioration of emission
Solution Approach 1:
The controller predicts the future fuel pressure and uses this prediction to set the target fuel pressure in advance. This allows the system to determine the appropriate injection amount based on the anticipated pressure state rather than using the conservative minimum injection amount, thereby maintaining injection accuracy while avoiding excessive fuel injection that would deteriorate emissions.
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 solution effectively reduces the duration and extent of over-rich air-fuel ratios, minimizing the risk of emission deterioration and accidental fires by ensuring a more precise fuel injection and torque management.
Implementation Method 1
in boosting of suctioned air by the forced induction device
Implementation Method 2
a rotating electric machine that generates electric power with an output torque of the engine
Data Source
AI summary
A vehicle includes an engine including an injector of cylinder injection type and a forced induction device, a second motor generator that generates electric power with an output torque of the engine, and an ECU that controls the engine and the second motor generator. When an amount of intake air and a fuel pressure of the engine decrease in boosting of suctioned air by the forced induction device, the ECU reduces a decrease in the amount of intake air during a period in which an injection amount is equal to a minimum injection amount, and when an excessive torque is generated in the output torque of the engine along with reducing a decrease in the amount of intake air, the ECU absorbs the excessive torque by a power generation operation of the second motor generator.