Vehicular Drive Control Device for Shifting Shock Reduction
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Solution Overview
Problem
Vehicular drive systems with electrically controlled differential mechanisms and automatic transmissions face inadequate shifting control due to improper engine speed management, leading to inefficiencies in fuel economy and vehicle performance.
Innovation Solution
A control device that determines the speed ratios of continuously-variable and automatic transmissions based on target vehicle output and running speed to establish an optimal engine operating point, ensuring adequate shifting control and improved engine output management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the differential mechanism and automatic transmission are controlled independently, then each component can operate at its optimal performance, but the overall shifting control becomes inadequate and engine speed synchronization is lost
Solution Approach 1:
The control device merges the control of the differential mechanism and automatic transmission into a single integrated control system. The control device determines speed ratios for both transmissions simultaneously based on target vehicle output and running speed, ensuring coordinated operation and proper engine speed synchronization during shifting operations.
2Reliability
If the engine speed is not properly managed during shifting, then the shifting control becomes inadequate, but implementing complex speed management reduces system simplicity
Solution Approach 1:
The control device performs preliminary determination of the optimal engine operating point before shifting operations. By calculating the target speed ratios for both transmissions based on desired vehicle output and current running speed, the system prepares the engine speed in advance to ensure proper synchronization during the actual shifting process.
Data Source
AI summary
Upon shifting control of differential mechanism 10, speed ratio γ0 of continuously-variable transmission portion 11 and speed ratio γ of automatic transmission portion 20 are determined by vehicle-output control device 82 on the basis of target engine output PE* and vehicle speed V, so as to establish an operating point of engine 8 which provides the target engine output PE* and which follows an optimum-fuel-economy curve, and the shifting control of the continuously-variable transmission portion 11 and the shifting control of the automatic transmission portion 20 are effected substantially concurrently, so that engine speed NE continuously changes, and the differential mechanism 10 is shifted with a reduced shifting shock. Further, the speed ratio γ0 of the continuously-variable transmission portion 11, in other words, the engine speed NE is changed by using first electric motor M1 and/or second electric motor M2, permitting an improvement in shifting response of the differential mechanism 10.