Hybrid Vehicle Torque Control to Suppress Particulate Matter
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Solution Overview
Problem
Hybrid vehicles with internal combustion engines and forced induction devices face challenges in managing particulate matter emissions and drivability, particularly in low-rotation, high-torque regions where increased load during boosting leads to elevated particulate matter generation, resulting in deteriorated emissions and drivability issues.
Innovation Solution
A control method for hybrid vehicles that includes restricting the torque increasing rate of the internal combustion engine and utilizing the rotating electrical machine to complement the restricted torque, thereby avoiding the particulate matter generating region, and using the rotating electrical machine to supplement the output when necessary to maintain drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the output of the internal combustion engine is restricted to avoid the PM generating region, then emission is improved, but drive torque or drive force cannot be generated and drivability deteriorates
Solution Approach 1:
The patent combines the output of the internal combustion engine with the output of the rotating electrical machine to meet the requested drive torque. When the engine operating point would fall in the PM generating region, the controller restricts engine torque increase rate and supplements the torque deficit with the rotating electrical machine, thereby avoiding high PM emissions while maintaining sufficient total drive torque for good drivability.
Solution Approach 2:
The patent changes the control parameter from simple output restriction to torque increasing rate restriction. By controlling the rate at which torque increases rather than restricting absolute torque levels, the system can gradually transition through the PM generating region, reducing PM emissions while still delivering the required drive force to maintain drivability.
2Object-generated harmful factors
If the torque increasing rate is restricted to avoid the PM generating region, then particulate matter emission is suppressed, but the requested drive torque cannot be fully met
Solution Approach 1:
The controller merges the restricted engine torque with torque from the rotating electrical machine to achieve the requested drive torque. When engine torque increase is limited to avoid the PM generating region, the rotating electrical machine provides supplementary torque, ensuring that the combined output meets the vehicle's power requirements while keeping engine PM emissions suppressed.
Solution Approach 2:
The rotating electrical machine acts as an intermediary that compensates for the torque limitation imposed on the internal combustion engine. By introducing this intermediate power source, the system can restrict engine operation to low PM regions while the electrical machine bridges the torque gap, maintaining sufficient total power output.
Data Source
AI summary
A vehicle includes: a motor generator; an engine having a forced induction device; and a HV-ECU. An operation region of the engine includes a PM generating region in which an amount of particulate matters included in exhaust gas of the engine is more than a predetermined amount due to a load of the engine being abruptly increased during boosting by the forced induction device. The PM generating region is a low-rotation and high-torque region. When assistance by the motor generator is sufficiently obtained and the engine is operated in the PM generating region, the HV-ECU restricts an increasing rate of the torque of the engine to be less than or equal to an upper limit rate. The HV-ECU complements, by the torque of the motor generator, the torque of the engine restricted by restricting the increasing rate of the torque of the engine.