Hybrid Vehicle Controller for Downshift Power Management
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Solution Overview
Problem
In hybrid vehicles with engines and rotary machines, the necessary discharging electric power required for downshifts often exceeds the upper-limit discharging electric power, leading to deterioration in gear shift responsiveness due to extended time requirements.
Innovation Solution
A controller with a prediction unit and control unit that adjusts the compressor rotation speed of the supercharger to increase its rate of increase as upper-limit discharging electric power decreases, ensuring the necessary discharging electric power does not exceed the limit and improving gear shift responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the time required for downshift progress is extended to prevent necessary discharging electric power from exceeding upper-limit discharging electric power, then the power storage device discharge limitation is respected, but gear shift responsiveness deteriorates
Solution Approach 1:
The invention changes the parameter of compressor rotation speed increase rate dynamically. When downshift is required and upper-limit discharging electric power is low, the controller increases the compressor rotation speed at a higher rate, which rapidly increases engine torque and reduces the assist torque needed from the rotary machine, thereby reducing necessary discharging electric power. This parameter change resolves the contradiction by allowing faster downshift execution without exceeding discharge limits.
2Speed
If the compressor rotation speed increase rate is increased to reduce necessary discharging electric power, then gear shift responsiveness is improved, but the control system complexity increases
Solution Approach 1:
The controller implements feedback control by continuously monitoring upper-limit discharging electric power (determined from power storage device state) and adjusting the compressor rotation speed increase rate accordingly. The prediction unit predicts necessary discharging electric power based on current operating conditions, and the control unit adjusts compressor speed in response to this prediction and the measured upper-limit power, creating a closed-loop control system that manages complexity through structured feedback mechanisms.
Solution Approach 2:
The prediction unit performs preliminary calculation of necessary discharging electric power before the downshift is executed. This preliminary action allows the control system to determine in advance whether the power storage device can handle the required discharge, and pre-adjust the compressor rotation speed increase rate accordingly, avoiding the need for complex real-time adjustments during the downshift execution.
3Reliability
If the necessary discharging electric power is reduced by increasing compressor rotation speed rate, then the power storage device is protected from overload, but energy consumption by the supercharger increases
Solution Approach 1:
The invention applies partial excessive action by increasing the compressor rotation speed at a rate higher than normal specifically during the downshift period when power storage device protection is critical. This temporary excessive action is confined to the necessary time window for downshift execution and does not represent continuous excessive energy consumption. The high increase rate is applied only partially in time and only when predicted necessary discharging electric power would otherwise exceed upper limits.
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 prevents necessary discharging electric power from exceeding upper-limit discharging electric power, thereby curbing deterioration in gear shifting responsiveness by optimizing the rate of increase in compressor rotation speed and supercharging pressure.
Implementation Method 1
a supercharger SC that includes an exhaust turbine type supercharger 18 and an electric supercharger 48... a compressor rotation speed sensor 94 that detects a compressor rotation speed Ncmp of the supercharger SC... controlling the compressor rotation speed such that a rate of increase of the compressor rotation speed increases
Data Source
AI summary
A controller for a hybrid vehicle predicts whether necessary discharging electric power from a power storage device which is required to perform downshift in a transmission exceeds upper-limit discharging electric power of the power storage device when downshift in the transmission is performed in a hybrid vehicle travel mode and controls a compressor rotation speed such that a rate of increase of the compressor rotation speed of a supercharger at the time of performing downshift in the transmission increases as the upper-limit discharging electric power decreases when it is predicted that the necessary discharging electric power exceeds the upper-limit discharging electric power.