Hybrid Vehicle Engine Control for Sliding Down Speed
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Solution Overview
Problem
In hybrid vehicles, the sliding down speed becomes large due to limited torque from the second motor when permissible charge electric power is small, leading to inefficient electric power consumption and prolonged engine rotational speed increase.
Innovation Solution
The hybrid vehicle employs an electronic control unit to manage battery power within defined ranges, starting the engine and maintaining self-sustained operation by the first motor when sliding down is detected, and adjusting rotational speed to increase electric power consumption, thereby preventing significant torque limitation from the second motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the permissible charge electric power of the battery is small, then the battery can be protected from overcharge, but the torque from the second motor is significantly limited causing the sliding down speed to become large
Solution Approach 1:
The engine is started in advance when sliding down is tentatively detected (before confirmed detection) and when permissible charge electric power is equal to or smaller than the first prescribed electric power. This preliminary engine start ensures that the engine is already running and can quickly increase rotational speed when sliding down is confirmed, avoiding delays in power consumption increase that would otherwise limit the second motor's torque and cause large sliding down speeds.
2Ease of operation
If the engine is started after detection of sliding down, then the engine can begin operation, but it takes long time to increase rotational speed of the engine, thus taking long time to increase electric power consumption of the first motor
Solution Approach 1:
The engine start operation is performed in advance based on tentative detection of sliding down condition, rather than waiting for confirmed detection. This preliminary action ensures the engine is already running when sliding down occurs, enabling immediate or rapid increase in rotational speed and power consumption, thereby resolving the time delay issue.
Solution Approach 2:
The control strategy dynamically adjusts engine operation based on sliding down detection status and permissible charge electric power. When sliding down is tentatively detected and permissible charge electric power is low, the engine is started and its rotational speed is increased to a target value larger than before sliding down. This dynamic adjustment optimizes the balance between ease of operation and time to increase rotational speed.
3Power
If the torque from the second motor is limited to a small value, then the battery charge electric power can be managed within permissible limits, but the sliding down speed becomes relatively large
Solution Approach 1:
The control strategy changes the parameter of engine rotational speed to a target value that is larger than the rotational speed before sliding down was detected. This parameter change increases the electric power consumption of the first motor, which allows the second motor to operate at higher torque values without causing excessive battery charging, thereby reducing the sliding down speed while managing power within permissible limits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach promptly increases engine rotational speed and electric power consumption, preventing large sliding down speeds and ensuring adequate torque from the second motor, while protecting the battery by limiting drive control when voltage or charge is low.
Implementation Method 1
the first motor such that the engine is driven by the first motor
Implementation Method 2
electric power that is generated by regenerative operation of the generator motor
Data Source
AI summary
In a hybrid vehicle, an electronic control unit is configured to: control an engine such that the engine is started and a self-sustained operation is performed in a case where i) torque for forward traveling is output from a second motor, ii) sliding down of the vehicle is tentatively detected before the sliding down is detected, and iii) permissible charge electric power is equal to or smaller than first prescribed electric power and rotation of the engine is in a stopped state; and execute drive control such that fuel injection is stopped and the engine is driven by a first motor at a rotational speed larger than that before the sliding down is detected in a case where i) the sliding down is detected thereafter and ii) the permissible charge electric power is equal to or smaller than second prescribed electric power.