Exhaust Valve Lock Phase Control for Engine Startup Emissions
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Solution Overview
Problem
Internal combustion engines face challenges in reducing unburned hydrocarbon (HC) emissions, particularly at startup, especially in low-temperature conditions, where fuel adhering to the cylinder wall does not burn due to insufficient combustion chamber temperature.
Innovation Solution
A control device for internal combustion engines that includes a lock mechanism to maintain the relative rotation phase of the exhaust valve open when the intake valve opens, allowing combustion gas to re-enter the chamber and increase the cylinder wall temperature, ensuring fuel evaporation and combustion, thereby reducing unburned HC emissions. This device uses a phase control valve to adjust the relative rotation phase between the driving and driven rotating bodies, and a control unit to manage the lock mechanism based on ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the exhaust valve timing is advanced to maintain overlap at startup, then unburned HC emissions are reduced, but the risk of backfire increases
Solution Approach 1:
The valve timing control mechanism transitions from a static fixed timing system to a dynamic variable timing system. The ECU controls the solenoid valves to advance or retard the exhaust valve timing based on real-time engine operating conditions (temperature, load, speed), allowing the system to optimize emissions at startup while preventing backfire under other conditions.
Solution Approach 2:
The system changes the timing parameter of the exhaust valve dynamically. By adjusting the opening and closing timing of the exhaust valve relative to the intake valve, the system creates or eliminates overlap periods to control emissions and prevent backfire based on engine state.
2Adaptability or versatility
If electromagnetic valve timing control is used to freely set opening/closing timing, then valve timing flexibility is improved, but device complexity increases
Solution Approach 1:
The system replaces traditional mechanical cam-based valve timing control with an electromagnetic control system. Solenoid valves are used to control oil pressure, which actuates pistons to adjust the timing of intake and exhaust valves, providing flexible electronic control over valve timing.
Solution Approach 2:
The electromagnetic valve timing control system serves multiple functions: it controls both intake and exhaust valve timing, adjusts timing based on various engine conditions (temperature, load, speed), and prevents both emissions problems and backfire risks through a single integrated control mechanism.
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
Effectively suppresses unburned HC emissions during engine startup by maintaining the exhaust valve open during intake, ensuring fuel evaporation and combustion, and transitioning to a high fuel efficiency state within a short period.
Implementation Method 1
a phase control valve capable of controlling the relative rotation phase of the driving rotating body and the driven rotating body, and the locked state, by supplying/discharging a fluid to/from an advancing chamber or a retarding chamber
Implementation Method 2
a lock mechanism switchable between a locked state in which a relative rotation phase of the driving rotating body and the driven rotating body is held in a predetermined first lock phase
Implementation Method 3
maintaining the open state of the exhaust valve when the intake valve opens... takes a portion of the combustion gas... into the combustion chamber... raise the temperature of the combustion chamber
Implementation Method 4
ensuring fuel evaporation and combustion
Implementation Method 5
the unburned HC gas contained in the exhaust gas contributes to combustion again
Data Source
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AI summary
The present invention is equipped with: a valve opening/closing timing control mechanism that sets the opening/closing timing of an exhaust valve; and a lock mechanism that holds the rotation phase of the valve opening/closing timing control mechanism in a first lock phase, in which the open state of the exhaust valve is maintained when the intake valve opens.