Hybrid Vehicle Engine RPM Control for Smooth Shifting
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Solution Overview
Problem
In hybrid vehicles, inexperienced drivers face issues with irregular torque changes and excessive engine RPM fluctuations during starting and shifting, leading to reduced ride comfort and anxiety due to the lack of effective engine and transmission control systems that correct for slow reactivity and jerking phenomena.
Innovation Solution
A method of controlling engine RPM and transmission by determining engine and transmission target RPMs and slopes, using PID control to synchronize engine RPM with target values, and controlling clutch actuator strokes to ensure linear starts and smooth shifting, even with inexperienced driver operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the vehicle uses conventional clutch operation control without separate transmission control, then the device complexity is reduced, but the ride comfort deteriorates due to irregular torque changes and excessive engine RPM fluctuations
Solution Approach 1:
The control system is segmented into two independent control loops: engine RPM control and transmission RPM control. The engine control unit manages engine speed while the transmission control unit manages transmission speed, allowing each to operate optimally without interfering with the other, thereby resolving the contradiction between simplicity and comfort
Solution Approach 2:
A separate transmission control unit acts as an intermediary between the driver's clutch operation and the transmission system. This intermediary provides smooth transmission control and compensates for abrupt clutch operations, improving ride comfort without significantly increasing overall system complexity
2Speed
If the engine RPM is allowed to fluctuate rapidly during shifting, then the response speed is improved, but the ride comfort deteriorates due to severe vehicle rumble and unstable engine RPM change
Solution Approach 1:
The transmission control unit dynamically adjusts the transmission RPM based on real-time operating conditions, clutch actuator position, and driver input. This dynamic control allows the transmission to respond quickly to shifting demands while simultaneously dampening RPM fluctuations that cause vehicle rumble, resolving the contradiction between response speed and ride comfort
3Ease of operation
If the clutch is coupled directly according to driver's pedal operation without separate actuator control, then the ease of operation is improved, but the manufacturing precision deteriorates due to inability to correct inexperienced driver operations
Solution Approach 1:
The transmission control unit automatically monitors and corrects clutch actuator position based on pre-stored optimal coupling characteristics. The system self-adjusts to compensate for inexperienced driver operations, maintaining precise clutch coupling without requiring the driver to have specialized skills, thus resolving the contradiction between ease of operation and coupling precision
Data Source
AI summary
A method of controlling an engine and a transmission of a hybrid vehicle includes steps of: determining whether the vehicle starts, determining an engine RPM and a gear stage of a transmission if the vehicle has started, determining whether the engine RPM has reached an engine speed control point, determining an engine target RPM and an engine target RPM slope of the vehicle when it is determined that the engine RPM has reached the engine speed control point, controlling the engine RPM of the vehicle to follow the engine target RPM and the engine target RPM slope, determining whether the engine RPM has slipped compared to the target engine RPM, and performing PID control to follow the engine target RPM if the engine RPM slips compared to the engine target RPM.