Piston Engine Inlet Valve Control Arrangement
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Solution Overview
Problem
Two-stage turbocharged engines face challenges in ensuring sufficient air intake during low engine loads and engine start due to shorter inlet valve opening times caused by high pressures and sharp cam nose forms, which existing control arrangements fail to adequately address.
Innovation Solution
A control arrangement featuring a cam profile with a portion under the base circle to control the delay in inlet valve closing, utilizing a hydraulic medium and guide member to extend the inlet valve opening time, and a separate cam device for auxiliary air supply, ensuring reliable air compensation under low load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure and sharp cam nose forms are used to increase charging action, then charging efficiency is improved, but inlet valve opening time is reduced
Solution Approach 1:
The invention uses a variable inlet valve closure arrangement where the inlet valve closing timing is dynamically adjusted based on engine operating conditions. Through a cam-operated mechanism with a piston device and hydraulic medium, the valve closure is delayed under specific conditions (low engine load, engine start) to extend the effective opening time when charging action is needed most
Solution Approach 2:
The invention changes the timing parameter of inlet valve closure based on engine operating conditions. A cam profile with a portion under the base circle controls a piston device that delays valve closure by controlling hydraulic medium flow. This parameter change allows extended opening time during low load and start conditions while maintaining normal timing during regular operation
2Object-affected harmful factors
If inlet valve closes early before bottom dead centre to minimise emissions, then emission control is improved, but air supply under low load is insufficient
Solution Approach 1:
The invention dynamically adjusts inlet valve closure timing based on engine load conditions. During low load operation and engine start, the variable closure arrangement delays valve shutdown to extend air intake duration. During normal operation, the valve closes at the optimized early timing to maintain emission control. This dynamic adaptation resolves the contradiction between emission control and air supply sufficiency
Solution Approach 2:
The cam-operated mechanism automatically detects and responds to engine operating conditions through the interaction of cam profiles, piston devices, and hydraulic pressure. The system self-adjusts valve closure timing without external intervention, extending opening time when air supply is critical (low load/start) while maintaining emission-optimized timing during normal operation
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 compensates for air deficits during low load situations and engine start by delaying inlet valve closure and enhancing air supply, maintaining smooth operation and reducing emissions without increasing total opening time.
Implementation Method 1
hydraulic medium can be selectively fed into the first chamber (13) for providing a delay in the closing of the inlet valve (3)
Implementation Method 2
the portion of the cam profile under the base circle is arranged to be utilised for controlling the releasing of pressure in the first chamber (13)
Data Source
Figure 1
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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 camshaft (4) and the valve mechanism (6). The cam device (5) includes a cam profile (5') having a portion (5c) arranged under a base circle (5a) of the cam profile (5'). Said portion (5c) of the cam profile (5') is arranged to control gas exchange through the inlet valve (3), specifically for providing a delay in the closing of the inlet valve (3).