Throttle Aspirator Controls Compressor Recirculation Valve
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Solution Overview
Problem
Turbocharger surge occurs in natural gas engines during transient throttle closing, leading to unstable operation, vibrations, and varying torque output, as existing systems fail to effectively control turbocharger operation without external control systems.
Innovation Solution
An engine system with a compressor recirculation valve (CRV) and gate valve that operate based on pressure changes within the system, forming a self-resetting loop, where the CRV is directly connected to a throttle aspirator, and a gate valve controls fluid communication with a vacuum reservoir, allowing compressed air to bypass the compressor and maintain stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a throttle is closed quickly in a natural gas engine, then the engine response time is improved, but surge occurs in the turbocharger causing unstable operation and vibrations
Solution Approach 1:
The aspirator is pre-configured in the control line of the compressor recirculation valve. When surge conditions occur, the aspirator automatically activates to modulate the recirculation valve, allowing compressed air to bypass the compressor inlet and stabilize the turbocharger before the full surge condition develops. This preliminary action prevents the instability that would otherwise result from quick throttle closing.
2Measurement precision
If an external control system is used to monitor and activate the CRV, then surge control precision is improved, but device complexity increases
Solution Approach 1:
The aspirator serves itself by using the pressure differential that naturally occurs during surge conditions to activate the control mechanism. The aspirator draws control air from the compressor outlet through its motive port, creating a vacuum at its suction port that automatically opens the recirculation valve when surge occurs. This self-service mechanism eliminates the need for external sensors, controllers, and power sources while maintaining precise surge control.
Solution Approach 2:
The aspirator acts as an intermediary device between the compressor outlet and the recirculation valve control chamber. It translates the pressure conditions during surge into a control signal that modulates the valve opening, providing precise control without requiring direct electronic intervention or complex control systems.
3Stability of the object's composition
If the CRV opens to allow compressed air to bypass the compressor, then surge is minimized, but compression pressure decreases
Solution Approach 1:
The recirculation valve is designed to dynamically modulate its opening based on the severity of surge conditions. The aspirator continuously adjusts the valve position in response to changing pressure differentials, allowing the system to maintain optimal balance between surge control and compression pressure. When surge is severe, the valve opens more to stabilize operation; when surge is minimal, the valve closes to maintain compression pressure.
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 minimizes surge during boost without an external control system, allowing the CRV and gate valve to automatically adjust based on pressure changes, ensuring stable turbocharger operation and reducing engine vibrations and torque variations.
Implementation Method 1
In a throttle closing transient this loss of compression causes the turbocharger to speed up, while simultaneously the flow rate of air into the engine is decreased
Implementation Method 2
increased flow occurs through the throttle aspirator thereby generating greater suction vacuum than during the steady state with no boost which evacuates the pneumatic control chamber of the compressor recirculation valve
Data Source
AI summary
An engine system having a compressor coupled to an engine and supplying air to an intake manifold, a throttle controlling the supply of air from the compressor to the intake manifold, a compressor recirculation valve (CRV) having a pneumatic control chamber, and a throttle aspirator having its motive section in fluid communication with an inlet of the throttle and its discharge section in fluid communication with an outlet of the throttle and its suction port in fluid communication with the pneumatic control chamber of the CRV. Such an engine system automatically minimizes surge during boost without a control system activating the CRV. Here, the CRV operates purely on the changes in pressure within the system forming a loop that resets itself. In another embodiment, a gate valve and a vacuum canister may be included rather than having the throttle aspirator directly connected to the CRV's pneumatic control chamber.