Hybrid ECU Correction Driving Force for Shift Comfort
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Solution Overview
Problem
Hybrid vehicles experience discomfort in driving feeling due to engine rotation speed changes during gear shifts, leading to insufficient acceleration force, especially after upshifts, as existing systems fail to effectively manage power distribution and engine rotation speed in response to shifting.
Innovation Solution
A hybrid vehicle system incorporating an electronic control unit that adjusts the target engine rotation speed and correction driving force based on shift stages and vehicle speed, utilizing power from the second motor to charge or discharge the battery, ensuring balanced power distribution and maintaining acceleration performance without altering engine power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the stepped gearshift upshifts with increase in vehicle speed, then fuel efficiency is improved through optimal engine operation, but the driver feels discomfort due to perceived decrease in acceleration force
Solution Approach 1:
The electronic control unit calculates a correction driving force in advance based on the elapsed time after upshift and the increase in vehicle speed after upshift. This correction force is applied to the base driving force before the upshift completes, ensuring that the driver perceives sufficient acceleration force while the engine operates at fuel-efficient rotation speeds.
2Ease of operation
If the target rotation speed of the engine is set for each shift level to limit required driving force, then driving feeling is improved, but acceleration force after upshifting becomes insufficient
Solution Approach 1:
The system dynamically adjusts the correction driving force based on real-time conditions including elapsed time after upshift and vehicle speed increase. This dynamic correction ensures that acceleration force is enhanced when needed (immediately after upshift) while allowing the engine to operate at optimal rotation speeds for fuel efficiency.
3Use of energy by moving object
If the engine operates without changing rotation speed during upshift, then fuel efficiency is maintained, but the driver does not perceive the expected speed change feeling
Solution Approach 1:
The electronic control unit continuously monitors the elapsed time after upshift and the increase in vehicle speed, using this feedback to calculate and apply an appropriate correction driving force. This feedback mechanism ensures that the driver perceives adequate acceleration force while the engine maintains fuel-efficient operation at constant rotation speed.
Data Source
AI summary
A hybrid vehicle includes an engine, a first motor, a planetary gear mechanism, a second motor, a battery, and an electronic control unit. The electronic control unit is configured to: set a shift stage based on a depression amount of an accelerator and a vehicle speed or a driver's operation; set a base driving force based on the degree of the depression amount of the accelerator, the vehicle speed, and a target rotation speed; set a correction driving force such that the correction driving force increases with an increase in elapsed time after upshifting or an increase in the vehicle speed after upshifting when the shift stage upshifts; and control the engine, the first motor, and the second motor such that a driving force obtained by correcting the base driving force using the correction driving force is output to the drive shaft.