Hybrid Vehicle ACC Torque Control for EV-to-HEV Switching
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Solution Overview
Problem
In hybrid vehicles with small motor output, especially mild hybrids, the adaptive cruise control (ACC) function faces challenges in achieving sufficient acceleration when starting from a standstill, leading to inadequate ability to follow the vehicle ahead due to insufficient motor torque, impacting both fuel efficiency and following performance.
Innovation Solution
A driving control apparatus that dynamically adjusts torque demands based on the acceleration rate of the vehicle ahead, switching from EV driving mode to HEV mode by executing a second torque demand with greater inclination, ensuring timely transition to engine-assisted acceleration, thereby enhancing the ability to follow the lead vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the vehicle operates in EV driving mode to enhance fuel efficiency, then fuel efficiency is improved, but acceleration performance and the ability to follow the vehicle ahead deteriorate due to insufficient motor torque
Solution Approach 1:
The patent implements dynamic switching between EV driving mode and HEV driving mode based on real-time detection of the lead vehicle's acceleration. When the lead vehicle accelerates, the system dynamically transitions from EV mode to HEV mode to provide sufficient acceleration, and can return to EV mode when acceleration is no longer required, optimizing both fuel efficiency and acceleration performance
Solution Approach 2:
The system changes the operating parameters by switching between different driving modes (EV and HEV) based on the acceleration state of the lead vehicle. This parameter change allows the vehicle to adapt its powertrain configuration to match the required acceleration performance while maintaining fuel efficiency during steady-state operation
2Speed
If the vehicle switches to HEV driving mode immediately to improve acceleration responsiveness, then the ability to follow the vehicle ahead is improved, but fuel efficiency deteriorates due to engine operation
Solution Approach 1:
The system dynamically determines the optimal driving mode based on the lead vehicle's acceleration state. Instead of operating in HEV mode continuously, the system switches to HEV mode only when the lead vehicle accelerates, and operates in EV mode during steady-state following, thereby achieving acceleration responsiveness when needed while maintaining fuel efficiency during normal operation
3Force
If the motor torque is increased to improve acceleration performance in EV mode, then the ability to follow the vehicle ahead is improved, but the complexity of the powertrain system increases
Solution Approach 1:
Instead of increasing motor torque through hardware modifications, the system dynamically manages torque delivery by switching between EV mode (motor-only) and HEV mode (engine+motor). This dynamic mode switching allows the system to achieve high acceleration performance when needed while maintaining a relatively simple powertrain architecture without requiring oversized motors or complex additional components
Data Source
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AI summary
[Problem to be Solved] To provide a driving control apparatus for a hybrid vehicle that achieves both enhancement of fuel efficiency and the ability to follow a vehicle ahead in an ACC function. [Solution] In a driving control apparatus for a hybrid vehicle (1) which has an ACC function that performs a constant speed cruising in accordance with a target vehicle speed when another vehicle ahead is not present in the vehicle's cruising lane and performs a following cruising with keeping a predetermined inter-vehicle time when the vehicle ahead is present in the vehicle's cruising lane, the driving control apparatus is configured, when the vehicle ahead which is being followed accelerates, to (i) execute acceleration control according to a first torque demand (T1) determined by an acceleration rate of the vehicle ahead in an engine driving mode or an HEV driving mode, and to (ii) execute acceleration control according to a second torque demand (T2) determined by an acceleration rate of the vehicle ahead in the EV driving mode, and the second torque demand (T2) increases with a greater inclination than the first torque demand.