Engine Torque Control via CVVD Intake Valve Timing
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Solution Overview
Problem
Existing engine control methods, particularly those using electronic throttle control (ETC) devices, suffer from reduced responsiveness and fuel economy losses when compensating for torque changes, either by adjusting air flow rates or ignition timing.
Innovation Solution
A method employing a continuous variable valve duration (CVVD) device to control intake valve timing and an ETC device to adjust air supply, allowing for rapid torque compensation by advancing or retarding intake valve closure and adjusting air volume in the combustion chamber, thereby enhancing engine responsiveness and preventing fuel economy deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ETC device adjusts air flow rate to compensate for torque changes, then torque compensation is achieved, but responsiveness is reduced and fuel economy deteriorates
Solution Approach 1:
The intake valve closure timing is adjusted in advance to prepare for torque changes. By controlling when the intake valve closes, the system pre-configures the combustion chamber conditions before combustion occurs, enabling faster torque response without waiting for air flow rate adjustments to take effect.
Solution Approach 2:
The invention changes the timing parameter of intake valve closure to control torque output. By varying the closure timing angle, the system directly influences the amount of air trapped in the combustion chamber, thereby adjusting torque output more rapidly and efficiently than air flow rate adjustment alone.
2Power
If ignition timing is changed to reduce engine torque, then torque reduction is achieved, but engine efficiency is reduced and fuel economy is lost
Solution Approach 1:
The intake valve closure timing is adjusted in advance to prepare for torque changes. By controlling when the intake valve closes, the system pre-configures the combustion chamber conditions before combustion occurs, enabling faster torque response without waiting for air flow rate adjustments to take effect.
Solution Approach 2:
The invention changes the timing parameter of intake valve closure to control torque output. By varying the closure timing angle, the system directly influences the amount of air trapped in the combustion chamber, thereby adjusting torque output more rapidly and efficiently than air flow rate adjustment alone.
3Speed
If CVVD device changes intake valve duration to adjust torque, then torque control responsiveness is improved, but device complexity increases
Solution Approach 1:
The camshaft mechanism is designed to serve multiple functions: it simultaneously controls both the opening and closing timing of the intake valve, as well as the duration of valve opening. By making the camshaft profile adjustable, a single component performs what would otherwise require multiple separate control mechanisms, reducing overall system complexity.
Solution Approach 2:
The camshaft profile is made dynamically adjustable to change the intake valve duration based on operating conditions. Instead of using fixed cam profiles, the system can modify the camshaft geometry in real-time, allowing the valve duration to be optimized for different torque requirements without adding complex control systems.
Data Source
AI summary
A method of controlling an engine which has a continuous variable valve duration (CVVD) device that controls an operation of opening or closing an intake valve, and an ETC device that controls an operation of opening or closing a throttle valve and adjusts the amount of air to be introduced into a combustion chamber, may include determining whether it is necessary to increase or decrease engine torque; changing a duration of the intake valve by using the CVVD device when it is necessary to increase or decrease the engine torque; and adjusting the amount of air introduced through the ETC device in a state in which the duration of the intake valve is changed.