Hybrid EV Start Control for Combustion Torque Shock Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid electric vehicles, the initial combustion torque can cause torque shock to the drive wheels, which is undesirable and needs to be suppressed.
Innovation Solution
A control device sets a target throttle valve opening degree based on the motor's rotational speed and engine coolant temperature to half-engage the clutch, allowing the motor to crank the engine, and initiates fuel injection and ignition only after the rotational speed difference between the motor and engine becomes smaller than a threshold, ensuring the clutch is fully engaged, thereby controlling the in-cylinder air amount to minimize initial combustion torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fuel injection and ignition are started immediately after clutch engagement, then the engine starts quickly, but the initial combustion torque increases causing torque shock to the drive wheels
Solution Approach 1:
The control device performs preliminary control of the throttle valve opening degree before fuel injection and ignition are started. By adjusting the throttle valve opening degree in advance based on motor rotational speed and coolant temperature, the in-cylinder air amount is controlled to ensure that when combustion starts, the initial combustion torque is suppressed to around zero, preventing torque shock to the drive wheels.
Solution Approach 2:
The control device changes the throttle valve opening degree parameter dynamically based on motor rotational speed and coolant temperature. By selecting appropriate throttle valve opening degrees from a map table according to these parameters, the control device optimizes the in-cylinder air amount to suppress initial combustion torque while ensuring reliable engine start.
2Ease of operation
If the clutch is half-engaged to crank the engine by the motor, then the engine can be started, but the rotational speed difference between motor and engine causes control complexity
Solution Approach 1:
The clutch serves as an intermediary element between the motor and the engine. By controlling the clutch to be half-engaged during the cranking phase and then fully engaged before combustion starts, the system enables smooth power transfer from the motor to the engine while minimizing rotational speed differences and simplifying the overall control process.
3Reliability
If the throttle valve opening degree is not optimized, then the engine can start, but the in-cylinder air amount causes increased initial combustion torque
Solution Approach 1:
The control device optimizes the throttle valve opening degree parameter based on motor rotational speed and coolant temperature to control the in-cylinder air amount. By selecting appropriate throttle valve opening degrees from a map table, the system ensures that when combustion starts, the initial combustion torque is suppressed to around zero, preventing torque shock while maintaining reliable engine start.
Data Source
AI summary
In start control for controlling an engine, a motor, and a clutch, a target throttle valve opening degree is set based on a rotational speed of the motor and a coolant temperature of the engine to control the engine such that the clutch is half-engaged to crank the engine by the motor, and fuel injection and ignition of the engine are started after a rotational speed difference between the rotational speed of the motor and a rotational speed of the engine becomes smaller than a threshold value and the clutch is engaged.