Variable Valve Timing Control Arrangement for Turbocharged Piston Engine
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbocharged piston engines face inefficiencies at low load operations due to compressor surging, inadequate air supply for self-ignition, and overheating of valves and components resulting from inefficient scavenging.
Innovation Solution
A control arrangement that adjusts the timing of inlet valve opening and closing, utilizing an asymmetric cam nose and a hydraulic medium-filled chamber to advance valve opening and provide a delay function, enhancing scavenging efficiency and cooling at low loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compressor operates at high pressure ratios to increase charge pressure, then the engine output and efficiency are improved, but the compressor is prone to surging at low load conditions which reduces pressure and flow supply
Solution Approach 1:
The patent implements dynamic valve timing control that adjusts the inlet valve opening timing based on engine load conditions. At low load conditions, the valve opens earlier to improve scavenging and prevent compressor surge. At high load conditions, normal timing is maintained to preserve high pressure ratio operation and engine output.
Solution Approach 2:
The patent changes the timing parameter of inlet valve opening dynamically. By advancing the inlet valve opening timing at low load conditions, the scavenging process is improved, allowing the compressor to operate stably without surge while maintaining adequate air supply for combustion.
2Device complexity
If the inlet valve opens later with standard cam timing, then the valve timing is simpler, but at low load situations the cylinders do not receive enough air for self-ignition during compression stroke
Solution Approach 1:
The patent applies preliminary action by opening the inlet valve earlier than the standard cam timing would dictate. This advance opening allows the cylinder to be pre-filled with air before compression begins, ensuring sufficient air quantity for self-ignition even at low load conditions where the turbocharger provides limited boost pressure.
3Productivity
If the valve timing is optimized for high pressure charging, then the charging action occurs in shorter time, but the valves and components overheat at low load situations due to inefficient scavenging
Solution Approach 1:
The patent dynamically adjusts valve timing based on operating conditions. At low load conditions, the inlet valve opens earlier to improve scavenging efficiency, which increases cooling airflow through the cylinder and valve components, preventing overheating. At high load conditions, the standard sharp cam timing is maintained to preserve fast charging action and high productivity.
4Reliability
If the inlet valve open time is extended for better scavenging, then low load cooling is improved, but the peak phase of valve opening must remain unchanged to maintain normal charging characteristics
Solution Approach 1:
The patent applies local quality by making only the initial portion of the valve opening event different from standard timing. The inlet valve opens earlier at the beginning of the stroke to improve scavenging, but the peak opening phase and closing timing remain unchanged to maintain normal charging characteristics. This localized modification achieves improved reliability without fundamentally altering the valve timing 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
This solution prevents compressor surging at full loads, improves scavenging efficiency, and allows for independent delay functions, ensuring better engine efficiency and reliability across varying load situations.
Implementation Method 1
a guide member (10) arranged at the lower end of the piston device (9) within the body part (8) and in engagement with and urged by a spring (11) towards a roller (12), which receives its guidance from a cam profile (5') of a cam device (5). The guide member (10) is provided with an auxiliary piston (13) movably fitted within it and which together with the guide member (10) define a chamber (14), into which hydraulic medium can be selectively fed for providing an advance in the time of opening of the inlet valve (3).
Data Source
Figure 1
Figure 2~2a
Figure 3~3a
AI summary
The invention relates to a control arrangement for gas exchange 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 cam device (5) and the valve mechanism (6), and a guide member (10) arranged in the body part (8) between the cam device (5) and the piston device (9) to be movably responsive with the movements of cam device (5). The control arrangement includes means for adjusting timing of valve opening of the inlet valve, said means cooperating with said piston device (9).