Vehicle Engine Valve Timing Control for Stop State Comfort
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Solution Overview
Problem
Existing vehicle systems fail to adequately control the open-close timing of intake and exhaust valves, leading to uncomfortable driver experiences, especially during engine operation in stop states due to insufficient oil supply for variable valve timing mechanisms.
Innovation Solution
A vehicle control method that adjusts the open-close timing of intake and exhaust valves using an operating fluid supply with the engine's output shaft, ensuring the engine operates at specific rotation speeds corresponding to predefined restrictions, thereby reducing driver discomfort and improving valve timing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates at high rotation speed to ensure sufficient oil supply for variable valve timing mechanism, then the valve timing control reliability is improved, but the driver experiences uncomfortable or odd feelings during vehicle stop state
Solution Approach 1:
The patent applies dynamics by making the oil supply system adjustable rather than fixed. The control valve dynamically adjusts the oil supply amount based on operating conditions (vehicle stop state vs. driving state), allowing the system to adapt between reliability requirements and comfort requirements. The camshaft rotation speed is dynamically controlled to match the actual oil supply capability, resolving the contradiction between maintaining reliable valve timing control and avoiding driver discomfort during stop states.
Solution Approach 2:
The patent changes key parameters (oil supply amount and camshaft rotation speed) based on operating conditions. During vehicle stop state, the control valve reduces oil supply amount and the engine control device lowers camshaft rotation speed, allowing the engine to operate at lower speeds without compromising valve timing reliability. During driving state, full oil supply and higher rotation speeds are restored. This parameter adjustment resolves the contradiction by matching system performance to actual operational needs.
2Adaptability or versatility
If the open-close timing of valves is changed by utilizing oil supply from the oil pump, then the variable valve timing function is achieved, but the oil supply becomes insufficient at certain engine rotation speeds
Solution Approach 1:
The system dynamically adjusts camshaft rotation speed to match oil supply capability. The control valve regulates oil flow based on actual supply conditions, and the engine control device adjusts camshaft speed accordingly. This dynamic coordination ensures the variable valve timing function remains reliable across different engine rotation speeds, resolving the contradiction between timing adaptability and oil supply reliability.
Solution Approach 2:
The system implements feedback control where the control valve monitors oil supply conditions and adjusts oil flow accordingly. The engine control device receives feedback about actual camshaft rotation and oil supply status, then adjusts control parameters to maintain reliable variable valve timing function. This closed-loop control ensures the system adapts to varying oil supply conditions and maintains timing reliability.
3Object-affected harmful factors
If the engine is controlled to operate at low rotation speed during vehicle stop state, then driver comfort is improved, but the oil supply for variable valve timing mechanism becomes insufficient
Solution Approach 1:
The system dynamically coordinates three elements: control valve opening degree, camshaft rotation speed, and engine rotation speed. During vehicle stop state, the control valve adjusts oil supply amount, the camshaft speed is lowered to match reduced oil flow, and the engine operates at lower speeds. This coordinated dynamic adjustment maintains sufficient oil supply for valve timing control while enabling low-speed operation for driver comfort.
Solution Approach 2:
The system changes multiple parameters simultaneously: control valve opening degree (affecting oil flow), camshaft rotation speed, and engine operation point. By coordinating these parameter changes, the system achieves sufficient oil supply at lower engine speeds, resolving the contradiction between driver comfort (low speed) and timing reliability (sufficient oil supply).
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 method effectively reduces driver discomfort by maintaining optimal engine operation at lower rotation speeds during stop states and ensures efficient valve timing adjustments, enhancing the overall driving experience.
Implementation Method 1
The variable valve timing mechanism may be structured to change the open-close timing of the intake valve by utilizing a supply of oil from an oil pump with rotation of the crankshaft of the engine
Data Source
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AI summary
When a power demand Pe* is not less than a preset reference value Pref2 in a vehicle stop state (steps S110 and S260), a target rotation speed Ne* of an engine is set to a rotation speed of not lower than a relatively low minimum rotation speed Nemin2 (step S290). A target timing VT* is set according to the set target rotation speed Ne* to have a smaller degree of advance, compared with the setting of the target timing VT* in an engine operating state for driving the vehicle (step S300). The engine is accordingly driven at the target rotation speed Ne* with an open-close operation of an intake valve at the target timing VT*. Such drive control effectively reduces the driver's uncomfortable feeling or odd feeling triggered by operation of the engine at a relatively high rotation speed in the vehicle stop state. The drive control also ensures the better open-close timing of the intake valve according to the operating condition of the engine and enables more appropriate control of a variable valve timing mechanism configured to adjust the open-close timing of the intake valve.