Hybrid Vehicle Mode Control for Manual Transmission EV Hold
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Solution Overview
Problem
In hybrid vehicles with manual transmission units, the existing mode switching technologies based on vehicle speed and accelerator opening degree often shift to HEV mode unnecessarily, leading to insufficient fuel efficiency improvements.
Innovation Solution
A control device that includes a manual transmission unit, an engine, a clutch, an electric motor, and a control unit that maintains the EV mode until the accelerator opening degree ratio exceeds a higher limit as the shift stage becomes a higher speed stage, using virtual engine rotation speed calculations and driver request torque maps to determine mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If mode switching is determined only by vehicle speed and accelerator opening degree, then the control system is simple, but the fuel efficiency improvement is insufficient due to unnecessary HEV mode shifts
Solution Approach 1:
The patent introduces driver request torque as an additional parameter for mode switching determination. The control unit calculates driver request torque based on accelerator opening degree and vehicle speed, and uses this parameter to determine whether to switch between EV mode and HEV mode. This additional parameter enables more accurate judgment of driver intent, preventing unnecessary mode shifts while maintaining control simplicity.
2Ease of operation
If the EV mode is maintained with a fixed accelerator opening degree threshold, then the control logic is simple, but driver comfort deteriorates due to frequent mode changes in higher gear stages
Solution Approach 1:
The patent makes the EV mode maintenance threshold dynamic by adjusting it according to the current gear stage. The control unit stores multiple threshold values corresponding to different gear stages (1st gear threshold, 2nd gear threshold, etc.), and selects the appropriate threshold based on the current gear stage. This dynamic adjustment reduces mode switching frequency in higher gear stages, improving driver comfort while keeping the control logic relatively simple through pre-stored threshold values.
3Loss of energy
If the accelerator opening degree threshold is lowered to prevent premature HEV mode shifts, then fuel efficiency improves, but the vehicle responsiveness to driver demand deteriorates
Solution Approach 1:
The patent uses driver request torque, calculated from accelerator opening degree and vehicle speed, as the basis for mode switching determination. By incorporating vehicle speed into the torque calculation, the system achieves more accurate reflection of driver intent. This allows the use of appropriate threshold values for different operating conditions, maintaining both fuel efficiency and responsive mode switching without requiring overly low fixed thresholds.
Data Source
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AI summary
[Problem to be Solved] To provide a control device for a hybrid vehicle capable of improving fuel efficiency by suppressing a shift to an HEV mode not required by a driver. [Solution] A control device for a hybrid vehicle includes: a manual transmission unit 4 allowing a driver to manually select an arbitrary shift stage; an engine 2 driving a drive wheel 6 through the manual transmission unit 4; a clutch 7 enabling or disabling the transmission of power between the engine 2 and the manual transmission unit 4; a motor generator 3; and an ECU 10 switching an EV mode allowing the vehicle to run only using the motor generator 3 as a drive source and an HEV mode allowing the vehicle to run using the engine 2 and the motor generator 3 as a drive source and maintaining the EV mode until a ratio with respect to an upper limit of an accelerator opening degree becomes larger as the shift stage of the manual transmission unit 4 becomes a higher speed stage.