Turbocharger Speed Control via Fuel Flow Regulation
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Solution Overview
Problem
Existing control systems for turbochargers, such as those described in U.S. Pat. No. 6,192,867, are overly complex and limited in their ability to prevent turbocharger failure due to excessive speed, particularly when using variable geometry turbochargers with exhaust flow control devices, and may not accurately reflect actual turbocharger speeds.
Innovation Solution
A control system that includes a sensor to monitor turbo speed, a controller to compare the turbo speed to a predetermined limit, and a fuel system to regulate fuel flow into the engine, allowing for continuous regulation of turbo speed and air intake pressure, with the option to limit fuel flow when turbo speed exceeds the set limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a control system uses exhaust flow control devices (VGT) to regulate turbo speed, then turbocharger performance can be optimized, but the system becomes more complex and the actuator response time increases, leading to potential turbo failure
Solution Approach 1:
The patent introduces a wastegate as an intermediary device between the exhaust manifold and the turbine. This wastegate acts as a simple flow control mechanism that directly limits exhaust flow to the turbine, providing a straightforward way to control turbo speed without relying on complex VGT actuators. The wastegate serves as a mediator that simplifies the control approach while maintaining effectiveness in preventing excessive turbo speed.
Solution Approach 2:
The patent extracts the speed control function from the complex VGT actuator system and implements it separately through a dedicated wastegate mechanism. By taking out the control function and implementing it through a simpler, more direct means (wastegate), the system reduces overall complexity while maintaining the ability to prevent turbo failure. This separation allows the VGT to focus on performance optimization while the wastegate handles safety and speed limitation.
2Ease of operation
If the actuator is slow to adjust vanes to decrease turbo speed, then turbocharger failure may occur due to excessive energy passing through the turbocharger
Solution Approach 1:
The patent implements preliminary action by pre-positioning the wastegate in a closed state or near-closed state, ready to immediately limit exhaust flow when excessive turbo speed is detected. This preliminary positioning of the wastegate ensures that the system can rapidly respond to dangerous conditions without waiting for a slow VGT actuator to adjust. The wastegate is prepared in advance to provide immediate protection, thereby maintaining reliability even when the primary actuator responds slowly.
Solution Approach 2:
The wastegate serves as a backup intermediary control mechanism that can independently protect the turbocharger when the primary VGT actuator fails to respond in time. By having the wastegate positioned to provide immediate flow limitation, the system ensures that there is always a reliable backup path for speed control, thereby maintaining turbocharger reliability despite actuator delays.
3Reliability
If fuel quantity is reduced to prevent excessive turbo speed, then turbocharger failure is prevented, but the control system becomes overly complex and may not accurately reflect actual turbo speed
Solution Approach 1:
The patent uses the wastegate as a direct intermediary control mechanism that physically limits exhaust flow to the turbine based on actual turbo speed conditions. This direct mechanical control provides a simpler and more accurate method of speed limitation compared to indirect fuel quantity control. The wastegate responds directly to turbo speed sensor feedback and provides immediate, accurate flow limitation without the complexity of multi-parameter fuel management systems.
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 effectively prevents turbocharger failure by continuously regulating turbo speed and air intake pressure, improving responsiveness and reducing the risk of excessive turbo speed, especially under adverse conditions like low oil temperatures or high altitude, by combining exhaust flow control with fuel flow regulation.
Implementation Method 1
Internal combustion engines such as, for example, diesel engines, gasoline engines, and gaseous fuel powered engines, combust a mixture of air and fuel to produce power.
Implementation Method 2
A turbocharger includes a turbine, driven by exhaust of the engine, to rotate a compressor and pressurize air directed into the engine.
Data Source
AI summary
A turbocharger control system is disclosed. The control system may have an engine and a fuel system configured to regulate fuel flow into the engine. The control system may further have an air induction system configured to regulate air flow into the engine and a sensor situated to sense a speed value of the air induction system. The controller may also have a controller configured to receive the speed value and regulate fuel flow into the engine as a function of the speed value.