Exhaust Vane Braking With Coordinated Throttle and Cam Control
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Solution Overview
Problem
Current gasoline engine braking strategies result in undesirable torque changes and reduced brake torque capability due to insufficient coordination of airflow actuators during transitions into and out of exhaust vane braking, especially in downsized engines.
Innovation Solution
A control system and method that coordinates the throttle, vanes on the turbine, and camshaft positions to smoothly transition into and out of exhaust vane braking, minimizing torque changes by optimizing airflow and pressure differentials, using a controller to manage the positions of the throttle, vanes, and cams to achieve maximum volumetric efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the throttle is closed to increase pumping work for engine braking, then negative torque output increases, but torque changes and instability occur during transitions
Solution Approach 1:
The controller pre-positions the vanes and cams before closing the throttle to enter exhaust vane braking mode. By anticipating the transition and preparing the airflow path components in advance, the system avoids sudden torque changes and maintains stability during the braking mode switch.
Solution Approach 2:
The controller continuously monitors engine parameters and dynamically adjusts vane and cam positions based on real-time feedback. This closed-loop control ensures smooth transitions into and out of exhaust vane braking while maintaining torque stability and preventing undesirable torque jumps.
2Volume of moving object
If downsized engines are used to reduce vehicle size, then vehicle dimensions decrease, but engine brake torque capability decreases
Solution Approach 1:
The system changes the operational parameters of the downsized engine by implementing exhaust vane braking with coordinated cam and vane control. This allows the smaller engine to generate sufficient brake torque by optimizing airflow dynamics and pressure differentials, compensating for the reduced engine displacement.
Solution Approach 2:
The patent introduces dynamic control of vanes and cams to maximize airflow through the engine during braking. By continuously adjusting these components based on operating conditions, the downsized engine achieves enhanced brake torque capability that would not be possible with static configurations.
3Loss of energy
If the throttle is closed to minimize airflow for engine braking, then pumping losses increase, but torque jumps occur during transitions
Solution Approach 1:
The controller pre-positions the vanes and cams before throttle closure to ensure the airflow path is optimized in advance. This preliminary configuration of airflow components prevents sudden torque jumps while maintaining the necessary pumping losses for effective engine braking.
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
Enhances brake torque output while avoiding undesirable torque jumps by actively controlling airflow and pressure differentials, thereby improving engine braking performance in gasoline engines.
Implementation Method 1
This difference in the intake manifold pressure and exhaust pressure is what generates most of the pumping losses within the engine. This pumping work directly relates to the negative torque output of the engine (engine braking).
Implementation Method 2
the intake and exhaust camshaft positions can be optimized allow higher amounts of air to flow through the engine
Data Source
AI summary
A control system and method for operating a gasoline engine comprising a turbocharger having a compressor and a turbine is provided. The system includes a throttle, vanes on the turbine, at least one cam, and a controller. The controller controls a transition into vane braking and is configured to: command the throttle to move to the closed position; command the vanes to the open position; determine whether additional negative torque is required; activate vane braking based on the determination that additional negative torque is required; command the vanes to the closed position; command the at least one cam to a maximum volumetric efficiency position; determine whether the at least one cam is at a maximum volumetric efficiency position; and command the throttle to the open position based on the determination that the at least one cam is at the maximum volumetric efficiency position.