Hybrid Vehicle Controller Mode Switching
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Solution Overview
Problem
Hybrid vehicles face challenges in achieving shorter mode switching times between electric vehicle (EV) and parallel hybrid vehicle (HV) modes, leading to potential driver discomfort due to response delays and clutch engagement shocks, especially at higher vehicle speeds or drive forces.
Innovation Solution
A hybrid vehicle system with a controller that dynamically switches between EV, series HV, and parallel HV modes based on vehicle speed, drive force, and driver input, ensuring the engine and clutch are engaged only when necessary, using a powertrain configuration with an engine, first motor, and second motor, and a clutch to optimize power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the clutch is engaged quickly to reduce mode switching time, then responsiveness is improved, but clutch engagement shocks and torque pulses increase causing driver discomfort
Solution Approach 1:
The controller performs preliminary actions by cranking the engine with the first motor before clutch engagement, and pre-synchronizing the clutch input and output shaft speeds using the first motor as a generator. This preparation reduces the engagement shock and allows faster switching without driver discomfort.
Solution Approach 2:
The first motor serves as an intermediary device between the engine and clutch engagement. It cranks the engine and acts as a generator to control the speed difference between clutch input and output shafts, mediating the engagement process to minimize shocks while maintaining fast switching.
2Speed
If the engine is cranked and ignited before clutch engagement, then responsiveness is improved, but engine torque fluctuations increase causing vehicle acceleration fluctuations
Solution Approach 1:
The controller continuously monitors engine speed and adjusts the first motor's generation output to maintain stable clutch input shaft speed despite engine torque fluctuations during combustion. This feedback control stabilizes vehicle acceleration while maintaining fast response.
3Object-affected harmful factors
If the clutch is engaged with synchronization control using the first motor, then engagement shocks are reduced, but mode switching time increases
Solution Approach 1:
The first motor performs preliminary speed synchronization of the clutch input shaft with the output shaft before engagement occurs. This pre-synchronization reduces the speed difference that causes shocks, enabling smooth engagement without excessive delay.
Solution Approach 2:
The controller periodically adjusts the first motor's generation output to maintain synchronization during the clutch engagement process, applying corrective actions at appropriate intervals to minimize shocks while maintaining fast switching.
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 allows for seamless mode switching without driver discomfort, reducing torque pulses, acceleration fluctuations, and engagement shocks, thereby enhancing drivability and responsiveness.
Implementation Method 1
a first motor disposed on an output side of the engine and having a function of generating electricity when driven at least by torque of the engine
Implementation Method 2
a second motor connected to drive wheels in a power transmittable manner
Data Source
AI summary
A hybrid vehicle in which a running mode can be appropriately shifted without making a driver feel uncomfortable or feel a sense of slowness. A hybrid vehicle includes an engine, a first motor, a second motor, and a clutch that selectively transmits power between the engine and drive wheels. A controller shifts a running mode to the parallel hybrid vehicle mode in a case of accelerating the hybrid vehicle in the electric vehicle mode, if the drive force is greater than a maximum drive force generatable in the electric vehicle mode, and also greater than a required additional drive force as a variable corresponding to a running resistance against the hybrid vehicle running on a predetermined running road at a predetermined vehicle speed by a predetermined drive force that is set in advance based on the vehicle speed and the drive force.