Internal Combustion Engine Torque Control for Clutch Engagement Shock
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Solution Overview
Problem
Existing engine control methods for internal combustion engines fail to adequately address the torque step difference at clutch engagement, leading to shock and unnatural feelings for the driver during restart, particularly when transitioning from inertia travel to connected driving.
Innovation Solution
Implementing a torque down control method that sets a target torque to a predetermined lower limit value based on the driving state, including vehicle speed and accelerator position, to manage clutch engagement and reduce shock during restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clutch is engaged to restart the internal combustion engine after automatic stop, then the driving force transmission is restored, but torque step shock is generated causing unnatural feeling to the driver
Solution Approach 1:
The control device performs preliminary torque down control before clutch engagement by reducing the target torque to a predetermined lower limit value. This preliminary action prepares the engine torque in advance to match the lower torque level that will be transmitted through the clutch, preventing torque step shock when the clutch engages and restores driving force transmission.
2Object-affected harmful factors
If the target torque is reduced to minimize torque step shock, then engagement shock is suppressed, but the acceleration characteristic of the vehicle deteriorates
Solution Approach 1:
The control device dynamically adjusts the target torque parameter to a predetermined lower limit value that is higher than the minimum possible torque. This parameter change balances two requirements: reducing torque step shock by limiting the torque reduction magnitude, while maintaining adequate acceleration characteristic by ensuring the lower limit value still provides sufficient driving force for vehicle acceleration.
3Speed
If the torque lower limit value is set high to ensure acceleration characteristic, then the response characteristic is improved, but torque step shock increases
Solution Approach 1:
The control device sets the target torque to a predetermined lower limit value that represents an optimized balance point. This parameter setting ensures the torque reduction is sufficient to prevent excessive shock while maintaining high enough torque to preserve acceleration and response characteristics, resolving the contradiction between these two performance aspects.
Data Source
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AI summary
According to the present invention, torque-down control is begun when the rotational speed difference between the engine rotational speed (Re) of an internal combustion engine that has started and the rotational speed (Rp) of a primary pulley has reached a second prescribed value (B) (step S5). A target torque (Tt) for the torque-down control is set to a torque minimum value Tmin that is calculated using vehicle speed and accelerator position (step S6). Thus, a minimum value for torque control during clutch engagement is set in accordance with operating conditions, which ensures the response performance of a vehicle during restarting of an internal combustion engine that has automatically stopped and makes it possible to suppress engagement shock during clutch engagement.