Compressor Trim Control for Deceleration Relief Whine
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Solution Overview
Problem
Internal combustion engines experience instability and noise issues due to backflow of compressed gas during transitions from acceleration to deceleration, leading to vibration excitation and hissing sounds, which existing solutions like bypass air systems and sound-absorbing elements are costly and space-consuming.
Innovation Solution
Implementing a trim control mechanism with a trimmer to variably cover the inlet cross-section of the compressor impeller, adjusting it during load removal to prevent backflow and minimize vibration excitation, combined with a throttle valve control to manage gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bypass air system is integrated into the compressor to avoid hissing sound during pressure relief, then the noise issue is resolved, but the cost and device complexity increase significantly
Solution Approach 1:
The invention extracts and eliminates the harmful backflow phenomenon by removing the marginal section of the inlet cross-section where backflow occurs. The trimmer covers the outer 10-30% of the inlet cross-section, taking out the problematic flow path and preventing compressed gas from flowing back over the impeller, thereby eliminating hissing noise without adding complex bypass systems
Solution Approach 2:
The invention converts the harmful backflow effect into a beneficial control mechanism by using the trimmer to deliberately restrict the inlet cross-section. This restriction prevents backflow during deceleration while maintaining or even improving compressor efficiency during normal operation by optimizing the flow distribution over the impeller blades
2Object-affected harmful factors
If sound-absorbing elements are integrated into the fresh gas line upstream of the compressor inlet to reduce hissing noise, then the noise issue is resolved, but the cost and installation space requirements increase
Solution Approach 1:
The invention extracts and eliminates the noise source at its origin by preventing backflow through trimmer control of the inlet cross-section. By covering the marginal section where backflow occurs, the system eliminates the vibration excitation and hissing sound before they can propagate through the fresh gas line, removing the need for downstream sound-absorbing elements and their associated space requirements
3Object-affected harmful factors
If the trim control is adjusted to cover the inlet cross-section during deceleration to prevent backflow, then noise and vibration are reduced, but the compressor efficiency may be affected
Solution Approach 1:
The invention implements dynamic control of the inlet cross-section area through the trimmer, which can be adjusted in real-time based on engine operating conditions. During deceleration, the trimmer covers the marginal section to prevent backflow and reduce noise. During acceleration and steady-state operation, the trimmer opens to maintain optimal flow and compressor efficiency, creating a dynamic adaptation to varying operational requirements
Solution Approach 2:
The invention applies local quality control by selectively covering only the marginal section (outer 10-30%) of the inlet cross-section while leaving the central flow path open. This localized restriction prevents backflow at the problematic edges without significantly impeding the main flow through the compressor, thereby minimizing the impact on overall compressor efficiency while effectively eliminating noise and vibration
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
Optimizes engine operation by preventing backflow and reducing noise, maintaining efficiency and reducing costs and space requirements compared to existing methods.
Implementation Method 1
The resulting nozzle effect of the trimmer allows the gas flow to be focused more strongly on the hub-adjacent inlet cross-section of the compressor impeller as the control intervention increases
Implementation Method 2
In the compressor of an internal combustion engine, the fresh gas supplied to the engine via a fresh gas stream is compressed
Implementation Method 3
Above an operating-point-dependent threshold for the incidence, the so-called surge line, the flow separates at the leading edges, and the flow within the compressor becomes unstable
Data Source
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AI summary
A method for operating an internal combustion engine is provided, wherein the internal combustion engine comprises at least one combustion engine and a fresh gas stream, and wherein a compressor is integrated into the fresh gas stream, to which a trim control is assigned. This trim control allows for variable coverage of a marginal portion of the inlet cross-section of a compressor impeller. In the enabled position (Sn) of the trim control, the marginal portion of the inlet cross-section is relatively little covered, and in the covered position (ST2) of the trim control, it is relatively extensively covered. The trim control is designed to be moved to the covered position (ST2) during the transition from acceleration (Sn) to deceleration (S2) of the combustion engine. This prevents or minimizes the so-called relief whine.