Hybrid Vehicle Engine Control for Forced Induction Lag
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Solution Overview
Problem
Hybrid vehicles with forced induction devices experience acceleration lag due to response delay in boost pressure, leading to poor drivability when the accelerator is quickly re-engaged after being turned off, especially in sport running modes where fuel efficiency improvements are not prioritized.
Innovation Solution
A hybrid vehicle control method that sets a smaller upper limit for the change in engine operating points during forced induction, slowing down the change in boost pressure and engine rotation speed, thereby maintaining boost pressure and preventing quick engine stoppages, which reduces acceleration lag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped or power is lowered when the accelerator is turned off to improve fuel efficiency, then fuel efficiency is improved, but acceleration lag occurs when the accelerator is quickly re-engaged due to boost pressure response delay
Solution Approach 1:
The control system dynamically adjusts the upper limit value of operating point change based on the engine's current operating state. When the engine is in the forced induction range (turbocharger active), a smaller upper limit is applied to maintain boost pressure. When outside this range, a larger upper limit allows faster response. This dynamic adaptation resolves the contradiction by optimizing behavior for different operating conditions.
Solution Approach 2:
The invention changes the control parameter (upper limit value of operating point change) based on the engine's operating range. By detecting whether the engine is in the forced induction range and adjusting the upper limit accordingly, the system achieves both fuel efficiency improvement and acceleration responsiveness without physical modifications to the engine or turbocharger.
2Speed
If the operating point changes rapidly to respond to accelerator input, then acceleration responsiveness is improved, but boost pressure cannot be maintained leading to acceleration lag
Solution Approach 1:
The system dynamically determines the upper limit value based on the current operating state. When in the forced induction range, the smaller upper limit maintains boost pressure stability. When outside this range, the larger upper limit enables rapid response. This dynamic control resolves the contradiction between responsiveness and stability.
Solution Approach 2:
The control system continuously monitors the engine's operating state (detecting whether it is in the forced induction range) and uses this feedback to adjust the upper limit value of operating point change. This closed-loop control ensures that the system maintains appropriate behavior for the current state, resolving the contradiction between rapid response and boost pressure maintenance.
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 effectively suppresses acceleration lag and improves drivability by maintaining boost pressure and controlling engine speed changes, even when the accelerator is quickly re-engaged, enhancing vehicle performance in sport running modes.
Implementation Method 1
an engine 13 including a forced induction device 47
Implementation Method 2
a motor generator 14 that generates electric power by using motive power of the engine 13
Data Source
AI summary
An HV-ECU performs processing including calculating requested system power, calculating requested engine power when an engine activation request has been issued, setting an operating point on a predetermined operating line, setting an upper limit value of magnitude of an amount of lowering in engine rotation speed to a first value when a vehicle is in a sport running state and when the previous operating point is within a forced induction range, setting the upper limit value to a second value when the vehicle is not in the sport running state or when the previous operating point is not within the forced induction range, correcting the operating point, and outputting an engine operation state command, a first MG torque command, and a second MG torque command.