Intake Valve Control Reduces Engine Startup Vibrations
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Solution Overview
Problem
Internal combustion engines experience strong vibrations during startup due to increased compression torque caused by elevated intake manifold pressure, which existing control methods fail to adequately mitigate.
Innovation Solution
A control device that determines the open-closed state of intake valves and adjusts the throttle valve opening degree to a first opening degree larger than the idling setting when an intake valve is open, preventing pressure increase in the intake manifold and reducing compression torque-induced vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the throttle valve is closed during engine startup, then the amount of intake air is reduced, but the compression torque increases due to pressure increase in the intake manifold
Solution Approach 1:
The control device determines the startup state of the internal combustion engine in advance and proactively adjusts the throttle valve opening degree before the compression stroke occurs. By setting the throttle valve to a predetermined opening degree based on the determined startup state, the system prevents excessive pressure buildup in the intake manifold before it happens, thereby reducing compression torque while still limiting intake air amount.
Solution Approach 2:
The control device continuously monitors the operational state of the internal combustion engine and uses this feedback to dynamically adjust the throttle valve opening degree. By determining whether the engine is in a startup state and responding accordingly, the system creates a closed-loop control that balances intake air management with compression torque reduction, preventing the harmful effect of excessive compression torque during startup.
2Stress or pressure
If the throttle valve is fully closed during startup, then negative pressure is generated in the intake manifold, but strong vibrations occur due to increased compression torque
Solution Approach 1:
The control device changes the parameter of throttle valve opening degree to a predetermined value during startup state, rather than maintaining it at fully closed position. This parameter adjustment allows the intake manifold to maintain appropriate negative pressure for engine startup while preventing excessive compression torque that would cause strong vibrations, thus resolving the contradiction between generating negative pressure and avoiding harmful vibrations.
3Quantity of substance
If the intake valve of one cylinder is open on compression stroke while other cylinders are closed, then air is supplied to the intake manifold from the open cylinder, but pressure in the intake manifold increases
Solution Approach 1:
The control device determines the startup state and the specific opening state of intake valves in advance, and proactively adjusts the throttle valve opening degree before the compression stroke completes. By taking preliminary action based on the determined state, the system prevents pressure buildup in the intake manifold that would occur if air is supplied from the open cylinder during compression, while still allowing necessary air supply for engine operation.
Data Source
AI summary
A control device for an internal combustion engine is provided. The internal combustion engine includes a plurality of cylinders. The internal combustion engine is configured such that when an intake valve of one cylinder on a compression stroke among the plurality of cylinders is open, an intake valve of each of the remainder of the plurality of cylinders is closed. The control device includes an electronic control unit configured to: (i) determine an open-closed state of the intake valve of each of the plurality of cylinders; and (ii) adjust an opening degree of a throttle valve to a first opening degree that is larger than a second opening degree corresponding to an idling operation, when the electronic control unit determines that the intake valve of any one of the plurality of cylinders is open at the time of startup of the internal combustion engine, to reduce compression torque and vibrations.