Hybrid Gear Shift via Engine Torque and Motor Speed Control
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Solution Overview
Problem
Conventional gear shift methods in parallel hybrid vehicles require long synchronization times due to high inertia of the internal combustion engine, leading to prolonged shifting processes, high switching forces, and potential wear, as well as uncomfortable shifting noises and fuel inefficiencies.
Innovation Solution
A method that combines torque-controlled operation of the internal combustion engine with speed-controlled operation of the electric machine for speed synchronization, allowing the two to work together during gear changes, reducing shifting times and improving driving comfort and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric machine operates in speed control mode to synchronize the transmission speed to the target speed, then the speed synchronization is achieved, but the synchronization time becomes comparatively long due to the high inertia mass of the internal combustion engine
Solution Approach 1:
The patent combines speed-controlled operation of the electric machine with torque-controlled operation of the internal combustion engine to perform speed synchronization. The control unit coordinates both machines to work together, with the electric machine providing speed control and the internal combustion engine providing torque control, thereby reducing the synchronization time compared to using the electric machine alone.
Solution Approach 2:
The patent dynamically switches between different control modes (speed control and torque control) for the electric machine and internal combustion engine during the gear shift process. The control unit adjusts the operational mode based on the synchronization requirements, enabling faster adaptation to the target speed.
2Ease of operation
If very high switching forces are applied to achieve gear shifting at very low temperatures, then the gear shift becomes possible, but the actuator may no longer be able to supply the required forces and excessive wear or transmission damage may occur
Solution Approach 1:
The patent merges the operational capabilities of the electric machine and internal combustion engine to provide the necessary switching forces during gear shifts. By coordinating both machines, the system can generate sufficient torque at low temperatures without overloading the actuator, as the combined torque from both machines reduces the burden on individual components.
3Productivity
If the electric machine operates alone to synchronize speed during gear shifts, then the gear change is achieved, but the shifting time is prolonged and fuel consumption increases
Solution Approach 1:
The patent combines the operational strengths of both the electric machine and internal combustion engine to achieve faster gear shifts. The internal combustion engine contributes torque control while the electric machine provides speed control, resulting in reduced synchronization time and improved productivity, while the coordinated operation optimizes energy utilization and reduces overall fuel consumption.
Data Source
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Figure 3A~3B
AI summary
The invention relates to a method for implementing gear shifting in a parallel hybrid vehicle whose drivetrain comprises an internal combustion engine, an electric machine capable of both motor and generator operation, and a transmission. During a gear change, the electric motor is used to synchronize the transmission speed with a target speed of the internal combustion engine. According to the invention, speed synchronization is achieved via torque-controlled operation of the internal combustion engine and speed-controlled operation of the electric machine (S3), thereby achieving shorter shift times.