Inlet Valve Control Arrangement for Variable Closure Delay
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Solution Overview
Problem
Four-stroke internal combustion engines, especially two-stage turbocharged engines, face challenges in ensuring sufficient air intake during compression strokes, particularly at low engine loads and start-up, due to shorter cam nose forms and lower boost pressures, which complicates inlet valve timing and emission control.
Innovation Solution
A control arrangement with multiple flow ducts and control means allows for selective delay in inlet valve closure by routing hydraulic medium flow between chambers, enabling adjustable delay times based on engine load and conditions, utilizing pneumatic control systems and charge air from the turbocharger to manage valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inlet valve opening time is extended to provide sufficient air during low load and start-up conditions, then air intake is improved, but emissions control deteriorates because the inlet valve must close early before bottom dead centre to minimise emissions
Solution Approach 1:
The inlet valve closure timing is made variable through a control arrangement that delays closure using hydraulic medium pressure. The system dynamically adjusts the valve closure timing based on engine operating conditions, allowing extended opening times during low load and start-up while maintaining early closure during normal operation for emissions control
Solution Approach 2:
The system changes the timing parameter of inlet valve closure by using hydraulic pressure to delay closure. The control arrangement modifies the closure timing parameter from the cam profile specification by applying hydraulic force to the piston device, enabling adaptation to different operating conditions
2Device complexity
If a single flow duct is used for delaying inlet valve closure, then the construction is simple, but only one fixed delay time is available which cannot adapt to different operating conditions
Solution Approach 1:
The single flow duct is segmented into multiple parallel flow ducts (first, second, third flow ducts), each providing a different delay time. This segmentation allows the system to offer multiple delay options while keeping each individual duct relatively simple in structure
Solution Approach 2:
The control arrangement is designed to be multi-functional by incorporating multiple flow ducts that can be selectively activated. The system can adapt to different operating conditions (low load, start-up, normal operation) by selecting appropriate delay times, making it universally applicable across various engine operating scenarios
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 a reliable and adaptable mechanism for extending inlet valve opening times, improving air intake and reducing emissions by allowing for variable inlet valve closure, optimizing engine performance across different load conditions.
Implementation Method 1
a control arrangement for an inlet valve (3) in a piston engine (1), comprising a cam device (5) for operating the inlet valve (3), a piston device (9) in force transmission connection with the valve mechanism (6) and arranged to be movable between a first position corresponding to closed valve position and a second position corresponding to open valve position, a guide member (10) in engagement with and urged by a spring (11) towards a roller (12), which receives its guidance from a cam profile (5/) of the cam device (5), whereby the changes in cam profile (5/) are transmitted so as to affect the opening and closing of the inlet valve (3), a body part (8) defining a first chamber (13) into which hydraulic medium can be selectively fed via a feed duct (14) for providing a delay in the closing of the inlet valve (3)
Implementation Method 2
The control means are with advantage arranged to be operated pneumatically by making use of the control systems included in the engine. Specifically charge air from a turbocharger of said piston engine can be utilised for controlling the control means.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a control arrangement for an inlet valve in a piston engine adapted between a cam device (5) of a camshaft (4) of the engine (1 ) and an inlet valve mechanism (6) arranged to open and close the inlet valve (3) in association with a cylinder of the engine, which control arrangement (7) comprises a body part (8), in which a piston device (9) is movably arranged to be in force transmission connection with the camshaft (4) and the valve mechanism (6), said body part (8) and the piston device (9) together defining a first chamber (13), into which hydraulic medium can be selectively fed, and a second chamber (19) connected to the first chamber via duct means (18,18', 18"), the flow of hydraulic medium from the first chamber (13) to the second chamber (19) being controlled for providing a delay in the closing of the inlet valve (3). The body p a r t ( 8 ) i s provided with two or more flow ducts (18a,18b,18c;18'a,18'b;18"a,18"b,18"c) for arranging different routes for the flow of hydraulic medium from the first chamber (13) to the second chamber (19). Control means (17, 17', 17") are provided for selecting the route of flow to be utilised in each case to provide different closing delay.