Hybrid Vehicle Friction Torque Correction via Mode-Switched Calculation
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Solution Overview
Problem
Hybrid vehicles face challenges in accurately calculating friction torque of internal combustion engines due to variations in engine parts, leading to inconsistent electric power generation and potential system faults.
Innovation Solution
A control device for hybrid vehicles that includes a mode switching unit, operation state detection unit, assumed output value calculation unit, actual output value calculation unit, and friction torque calculation unit, allowing for accurate friction torque calculation by subtracting actual output values from assumed values in series mode, thereby accounting for variations in engine parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If friction torque correction based on rotational speed difference is applied to hybrid vehicles, then engine output torque correction is achieved, but accurate friction torque calculation becomes difficult due to changing load conditions
Solution Approach 1:
The patent applies dynamics by making the friction torque calculation adaptive to changing operating conditions. Instead of using a fixed correction method based on rotational speed difference, the system dynamically selects between series mode calculation (using generator power output) and parallel mode calculation (using rotational speed difference), allowing accurate friction torque determination across varying load conditions while maintaining adaptability to different driving scenarios
Solution Approach 2:
The patent implements parameter changes by switching between different calculation methods based on operating mode. In series mode, friction torque is calculated using generator electric power output parameters, while in parallel mode, rotational speed difference parameters are used. This parameter adaptation enables accurate friction torque calculation across different operational states of the hybrid vehicle
2Reliability
If engine output torque is not accurately corrected for friction variations, then vehicle operation becomes unstable, but excessive terminal voltage or insufficient state of charge occurs
Solution Approach 1:
The patent implements feedback by continuously monitoring the calculated friction torque and using it to correct engine output torque in real-time. The system feeds back the friction torque information to the engine control unit, which adjusts engine output accordingly, preventing harmful effects such as excessive terminal voltage or insufficient state of charge while maintaining reliable vehicle operation
Solution Approach 2:
The patent applies preliminary action by calculating and correcting friction torque before it causes harmful effects. The system proactively determines friction torque based on operating mode and pre-corrects engine output torque, preventing the development of excessive terminal voltage or insufficient state of charge conditions rather than reacting after problems occur
Data Source
AI summary
Assumed torque Tb is calculated based on an operation state of an engine when there is no abnormality in sensors, the engine is in a warm-up completion state, and a travel mode is a series mode, and actual torque Ta is calculated and friction torque Tf is calculated based on information on an actual amount of electric power generation of a generator. When the friction torque Tf is larger than an upper limit clip value, the upper limit clip value is the friction torque Tf, and when the friction torque Tf is smaller than the lower limit clip value, the lower limit clip value is the friction torque Tf, correction torque Tc is calculated, and an operation of an electronic control instrument of the engine is controlled so as to set the assumed torque Tb to the correction torque Tc.