Hybrid Vehicle Fuel-Cut Control for Smooth NV and Acceleration
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Solution Overview
Problem
Existing vehicle control systems face challenges in maintaining noise and vibration (NV) characteristics while ensuring responsiveness to acceleration requests after deceleration, particularly due to the deterioration of NV characteristics caused by fuel cut control and regenerative torque management.
Innovation Solution
A vehicle control device that executes fuel cut control, engages a lock-up clutch, and opens the throttle during deceleration, closes the throttle and performs motor assist during acceleration requests, resumes fuel supply when intake pressure reaches a predetermined negative pressure, and disengages the lock-up clutch to prevent torque shocks and maintain NV quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fuel cut control is executed during deceleration to improve fuel consumption and increase regenerative torque, then fuel efficiency and power generation are improved, but NV characteristics deteriorate due to engine instability
Solution Approach 1:
The lock-up clutch is engaged before fuel cut control to pre-establish a stable mechanical connection between the engine and motor generator. This preliminary action ensures that when fuel supply is stopped, the engine rotor maintains stable rotation through the locked clutch connection, preventing vibrations and noise during the fuel cut period while still allowing regenerative braking to occur.
2Power
If throttle is opened during fuel cut control to reduce pumping loss and increase regenerative torque, then power generation efficiency is improved, but engine stability and NV characteristics worsen
Solution Approach 1:
The lock-up clutch is engaged before opening the throttle during fuel cut control. This preliminary engagement ensures that when the throttle opens to increase regenerative torque, the engine rotor is already stably connected to the motor generator through the locked clutch, preventing the torque fluctuations and vibrations that would otherwise occur with sudden throttle changes.
3Speed
If acceleration request is made while lock-up clutch is engaged and throttle is opened, then vehicle responsiveness is improved, but torque shocks and NV deterioration occur
Solution Approach 1:
When an acceleration request is detected during fuel cut control with the lock-up clutch engaged, the system maintains continuous motor assist to bridge the transition period. The motor generator continues to provide torque support while the throttle is closed, ensuring smooth and continuous torque delivery to the drive wheels without interruption or shock, thereby maintaining acceleration responsiveness while preventing NV deterioration.
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
The solution effectively prevents the deterioration of NV characteristics while ensuring vehicle responsiveness to acceleration requests by managing regenerative torque and engine startup, reducing pumping losses and torque fluctuations.
Implementation Method 1
a lock-up clutch 134... configured to engage the lock-up clutch
Implementation Method 2
a torque converter 13... configured to output, to the drive wheel, power of at least one of the internal combustion engine and the electric motor transmitted via at least one of the torque converter and the lock-up clutch
Implementation Method 3
an internal combustion engine... execute a fuel cut control for stopping fuel supply to the internal combustion engine
Implementation Method 4
an electric motor coupled to the internal combustion engine... perform regenerative power generation
Data Source
AI summary
A vehicle control device is configured to: execute a fuel cut control for stopping fuel supply to the internal combustion engine in response to a deceleration request to the vehicle; engage the lock-up clutch and open a throttle of the vehicle during the execution of the fuel cut control; close the throttle and execute the motor assist in a case where there is an acceleration request to the vehicle while the lock-up clutch is engaged, the throttle is opened, and the fuel cut control is executed; end the fuel cut control and resume fuel supply to the internal combustion engine when an intake pressure of the internal combustion engine reaches a predetermined startable negative pressure after the throttle is closed; and disengage the lock-up clutch when the fuel supply to the internal combustion engine is resumed.