Hybrid Vehicle Control Apparatus for Engine Starting Shock Reduction
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Solution Overview
Problem
Conventional hybrid vehicle drive systems experience drivability deterioration due to engine starting shocks when operating exclusively in electric motor drive mode, primarily caused by significant differences in engine and transmission speeds.
Innovation Solution
A control apparatus that adjusts the transmission shift position based on an output-related value after engine start, minimizing the time required to transition to a hybrid drive mode by compensating shifting lines and synchronizing engine and transmission speeds, thereby reducing the duration for clutch engagement and improving drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the clutch is engaged when the difference between engine operating speed and transmission input speed is minimized, then the shock upon engine starting is reduced, but a comparatively long length of time is required before the clutch has been brought into its fully engaged state, giving rise to a risk of deterioration of the drivability of the hybrid vehicle
Solution Approach 1:
The transmission shift position is determined in advance based on the estimated engine operating speed after starting. By pre-calculating the appropriate shift position that will minimize the speed difference between engine and transmission, the system prepares the transmission for optimal clutch engagement conditions before the clutch is actually engaged, thereby reducing both shock and engagement time
Solution Approach 2:
The system changes the transmission shift position parameter based on the estimated engine operating speed. By adjusting which gear position is selected (e.g., selecting a lower gear to increase input speed or higher gear to decrease it), the system optimizes the speed matching between engine and transmission, resolving the contradiction between minimizing shock and reducing engagement time
2Device complexity
If the shift position of the transmission is not adjusted based on engine speed, then the control system remains simple, but the drivability deteriorates when the difference between engine operating speed and transmission input speed is large
Solution Approach 1:
The system dynamically changes the transmission shift position parameter based on the estimated engine operating speed after starting. This parameter adjustment allows the system to adapt to different engine speed conditions, improving drivability without requiring complex mechanical modifications to the clutch or transmission hardware
Solution Approach 2:
The system uses feedback from the estimated engine operating speed to determine the appropriate transmission shift position. By continuously monitoring and responding to engine speed conditions, the system optimizes clutch engagement performance while maintaining a relatively simple control architecture that processes speed data and selects appropriate gear positions
Data Source
AI summary
A control apparatus for a hybrid vehicle is provided with an engine, an electric motor, a clutch disposed in a power transmitting path between the engine and the electric motor, and a transmission of a step-variable type disposed in a power transmitting path between said electric motor and drive wheels, a shift position of said transmission to be established after a shift-down action thereof performed in a vehicle drive mode using said electric motor as a drive power source being selected on the basis of an output-related value after starting of said engine, and according to a predetermined relationship, when the starting of said engine is required together with said shift-down action.