Hybrid Vehicle Engine Speed Control for Supercharger Response Delay
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Solution Overview
Problem
Hybrid vehicles with superchargers experience acceleration performance degradation due to engine output shortages caused by supercharging response delays, which cannot be adequately supplemented by rotary machines due to battery constraints during control for producing acceleration feeling.
Innovation Solution
A control device for hybrid vehicles that sets a target engine rotation speed lower than optimal fuel efficiency, increasing it based on vehicle speed and time, and uses a drive control unit to supplement engine power shortages through rotary machines, with initial rotation speed and lower limits adjusted according to supercharging pressure and its change rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If control for producing acceleration feeling is performed by setting target engine rotation speed to initial rotation speed lower than optimal fuel efficiency, then acceleration response is improved, but engine output power becomes insufficient due to supercharging response delay
Solution Approach 1:
The control device increases the initial rotation speed before acceleration begins, and sets a higher rotation speed increase rate during acceleration. This preliminary preparation ensures that the engine reaches optimal operating conditions faster, compensating for the supercharger's response delay and maintaining sufficient output power throughout the acceleration process.
Solution Approach 2:
The system dynamically adjusts the rotation speed increase rate based on acceleration demand and supercharging pressure conditions. By making the rotation speed profile adaptive rather than fixed, the engine can optimize its response characteristics in real-time, balancing acceleration performance with power availability despite supercharger lag.
2Power
If rotary machine is used to supplement engine power shortage, then acceleration performance is maintained, but battery constraints limit the supplementation capability
Solution Approach 1:
By increasing the initial rotation speed and optimization rate before and during acceleration, the engine produces sufficient power earlier in the acceleration process. This reduces or eliminates the need for rotary machine supplementation, thereby preserving battery energy while maintaining acceleration performance.
3Use of energy by moving object
If target engine rotation speed is set lower than optimal fuel efficiency, then fuel efficiency is improved, but acceleration performance deteriorates due to supercharging delay
Solution Approach 1:
The control device prepares the engine by increasing initial rotation speed and setting higher increase rates before acceleration begins. This preliminary action ensures that when acceleration is demanded, the engine is already closer to optimal operating conditions, reducing the negative impact of supercharging delay and maintaining both fuel efficiency and acceleration performance.
Data Source
AI summary
When an acceleration request is issued, an electronic control unit for a hybrid vehicle performs control for producing an acceleration feeling of setting a target engine rotation speed to an initial rotation speed (=basic initial value+initial value correction value) which is lower than an optimal-fuel-efficiency rotation speed at which required engine power is able to be most efficiently output and increasing the engine rotation speed from the initial rotation speed to the optimal-fuel-efficiency rotation speed at a rotation speed increase rate (=basic increase rate+increase rate correction value) based on the elapse of time. When the target supercharging pressure is high, the initial value correction value is set to a greater value and the increase rate correction value is set to a greater value than when the target supercharging pressure is low.