Turbocharger Speed Control for Piston Engine Load Management
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Solution Overview
Problem
Turbochargers in piston engines are inefficient at low load operations and inefficient in high load operations due to compressor surging, which affects engine performance and fuel consumption.
Innovation Solution
A method of controlling turbocharger speed by adjusting intake and exhaust valve lift profiles and using a waste gate to manage charge air pressure, with the engine operating in two modes: one below a predetermined load and another above it, where the intake valve closes earlier and the waste gate is closed to increase boost pressure and air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a waste gate is used to bypass exhaust gases under higher load operation, then the compressor surge problem is mitigated, but specific fuel consumption increases
Solution Approach 1:
The patent applies dynamics by making the waste gate controllable and adjustable based on operating conditions. The waste gate is opened only when necessary to prevent compressor surge, and closed when not needed, allowing the system to adapt dynamically between different operating modes (surge prevention mode vs. efficiency mode) rather than being fixed in one state
Solution Approach 2:
The patent changes the operational parameters of the waste gate based on engine load and compressor operating conditions. By monitoring parameters such as compressor speed, charge air pressure, and engine load, the system adjusts the waste gate position to optimize both surge prevention and fuel efficiency, moving the operating point along the compressor map to maintain optimal efficiency
2Productivity
If high pressure ratios are used in the compressor to increase charge pressure, then engine performance improves, but compressor surge risk increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring compressor operating parameters (speed, charge air pressure, mass flow) and using this information to adjust the waste gate position and engine operating parameters. This closed-loop feedback system maintains the compressor operating point within the safe surge-free region while maximizing charge pressure for optimal engine performance
Solution Approach 2:
The system takes preliminary action by proactively adjusting the waste gate and engine parameters before the compressor reaches critical surge conditions. By anticipating surge risks based on predicted operating trends and pre-adjusting control parameters, the system prevents surge before it occurs rather than reacting after surge begins
3Power
If the engine operates at high load conditions, then power output increases, but thermal load on the engine increases
Solution Approach 1:
The patent converts the harmful effect of high thermal load into a beneficial control parameter by using exhaust gas temperature and charge air temperature as feedback signals to optimize the waste gate operation. The thermal load information is utilized to determine the optimal waste gate position that balances power output with thermal management, turning the thermal stress indicator into a useful control input
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 approach enhances turbocharger efficiency, reduces specific fuel consumption, and minimizes thermal load, while also reducing NOx emissions by advancing the inlet valve closing, thereby improving engine performance across varying load conditions.
Implementation Method 1
combustion air pressurised with the compressor part of the turbocharger arrangement
Implementation Method 2
utilizes energy of the exhaust gas of the engine. Thus, by using a turbocharger it is possible e.g. to increase the output and efficiency of the engine
Implementation Method 3
Combustion of fuel in a compression ignition internal combustion engine and converting the energy of the fuel into mechanical work
Data Source
Figure 1
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Figure 4~5
AI summary
Invention relates to method of controlling turbocharger speed of a piston engine in which method the engine is operated below or at a predetermined load and combustion air is pressurised with the compressor part, the intake valve is controlled by a first intake valve lift profile and fuel is combusted in the engine (10), the exhaust valve is controlled by a first exhaust valve lift profile. The engine is run in a second mode of operation above the predetermined load during which the closing of the inlet valve is advanced compared to that of the first mode of operation and the air flow between an outlet of the compressor part and an inlet of the turbine part is increased allowing more combustion air to flow through the compressor part (25.1).