Intake Valve Hydraulic Adjuster for Early Closing
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Solution Overview
Problem
Internal combustion engines face challenges in controlling combustion phasing, leading to misfires and cylinder-to-cylinder variability, especially at high EGR rates, due to poor calibration and non-uniform EGR distribution, which can result in increased NOx emissions and the need for expensive exhaust after-treatment systems.
Innovation Solution
A mechanism for variable valve actuation (VVA) in individual engine cylinders, specifically controlling intake valve closing, is introduced, combined with a turbocharger system and EGR control, using a hydraulic actuator and snubber to manage cylinder compression ratio and reduce NOx emissions without de-rating the engine or using costly after-treatment systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If expensive exhaust after-treatment systems (LNT or SCR catalyst) are used to limit NOx emissions, then NOx emissions are reduced, but engine power is de-rated and system cost increases
Solution Approach 1:
The hydraulic actuator performs preliminary action by closing the intake valve early in the compression stroke, before combustion occurs. This early valve closing pre-conditions the cylinder to achieve lower compression ratios and reduced peak temperatures, thereby preventing NOx formation at the source rather than treating it after emission
Solution Approach 2:
The system dynamically adjusts the intake valve closing timing based on real-time combustion phasing feedback from ion sensing technology. The hydraulic actuator can vary the valve closing point throughout the compression stroke, creating dynamic control over compression ratio and in-cylinder conditions to optimize combustion and minimize NOx without power loss
2Object-generated harmful factors
If expensive exhaust after-treatment systems (LNT or SCR catalyst) are used to limit NOx emissions, then NOx emissions are reduced, but system cost increases
Solution Approach 1:
The invention extracts the NOx control function from the exhaust system and relocates it to the intake valve actuation system. By implementing compression ratio control through variable intake valve timing, the system eliminates the need for separate exhaust after-treatment components like LNT or SCR catalysts, thereby reducing overall system cost and complexity
Solution Approach 2:
The patent replaces complex chemical after-treatment systems with a mechanical/hydraulic valve actuation system. The hydraulic actuator mechanism substitutes for chemical catalysts by physically controlling compression parameters to prevent NOx formation, achieving emission control through mechanical means rather than chemical treatment
3Ease of operation
If hydraulic actuator is used to control intake valve closing timing, then combustion phasing control is improved, but device complexity increases
Solution Approach 1:
The hydraulic actuator serves multiple functions: it controls intake valve closing timing, adjusts compression ratio dynamically, and responds to combustion feedback signals. This multi-functionality consolidates several control tasks into a single device, managing complexity by making one component perform multiple roles rather than adding separate mechanisms for each function
Solution Approach 2:
The system implements closed-loop feedback control where ion sensing technology monitors combustion phasing in real-time and feeds this information back to the hydraulic actuator. This feedback mechanism enables automatic adjustment of valve timing to maintain optimal combustion, simplifying operation while the control algorithm manages the complexity of real-time adjustments
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
This solution provides improved control over engine operation, reduces NOx emissions effectively, and avoids the need for expensive exhaust after-treatment systems by allowing for precise control of intake valve timing and compression ratio, enhancing engine efficiency and reducing emissions.
Implementation Method 1
A hydraulic actuator hydraulically locks the relocatable axis against relocation as the one valve is being increasingly opened by the rocker, and with the one valve open, unlocks the relocatable axis to allow the valve spring to increasingly expand and simultaneously force the one valve toward the valve seat and the relocatable axis to relocate
Implementation Method 2
The variable volume chamber of the snubber is cooperatively defined by a snubbing element and by a body with respect to which the snubbing element is extendable and retractable. The snubbing element and the snubber body collectively comprise a variable restriction through which the variable volume chamber of the snubber is in fluid communication with the accumulator
Implementation Method 3
A hydraulic fluid pressure source delivers hydraulic fluid through a first check valve to a variable volume chamber of a hydraulic snubber and through a second check valve to a variable volume chamber of the actuator
Implementation Method 4
with the one valve open, unlocks the relocatable axis to allow the valve spring to increasingly expand and simultaneously force the one valve toward the valve seat
Implementation Method 5
to a hydraulic accumulator that is in fluid communication with the snubber chamber and a first port of a control valve
Data Source
AI summary
A mechanism (40) for enabling an engine cylinder valve (18) to close at various times during engine cycles has a hydraulic actuator (58) and a control valve (60) controlling the hydraulic actuator a) to constrain a pivot axis of a valve rocker (52) against relocation while the cylinder valve is being forced increasingly open, and b) to release the constraint after the cylinder valve has been forced open for enabling the pivot axis to relocate so that the intake valve can close early thereby providing early IVC. A hydraulic snubber (64) snubs closing motion of the cylinder valve through a scheduling geometry to a hydraulic accumulator (62). The control valve opens to the accumulator to allow the rocker pivot axis to relocate and provide early IVC and closes to return the pivot axis to a location that doesn't provide early IVC.