AC Compressor Rear Housing Pulsation Reduction
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Solution Overview
Problem
Existing compressors, such as air conditioning compressors, generate significant noise, vibration, and harshness (NVH) due to fluid pressure pulsations, and existing noise control solutions like mufflers increase the compressor's size and induce flow loss.
Innovation Solution
A rear housing design with an annular outer and inner wall structure, featuring a tubular member with multiple holes that connect the discharge chamber to a passageway, allowing minimal flow loss while reducing pressure pulsations and NVH, by matching the number and size of holes to the pulsation frequencies and amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a built-in flow noise control device such as a muffler is added to the compressor, then NVH is reduced, but the overall size and mass of the compressor increases significantly
Solution Approach 1:
The noise control function is merged with the existing discharge chamber structure. The discharge chamber itself is configured to act as a flow noise control device through its specific geometry and the discharge passageway design, eliminating the need for a separate bulky muffler while maintaining NVH reduction benefits
Solution Approach 2:
The discharge chamber serves multiple functions: it collects discharged fluid, controls flow noise, and acts as part of the noise reduction system. This multi-functionality allows the existing structure to reduce NVH without adding extra components that would increase mass
2Object-affected harmful factors
If a built-in flow noise control device such as a muffler is added to the compressor, then NVH is reduced, but the overall size of the compressor increases significantly
Solution Approach 1:
The noise control functionality is integrated into the existing discharge chamber volume. By configuring the discharge chamber and discharge passageway with specific geometric features, the system achieves NVH reduction without requiring additional space for separate noise control components
Solution Approach 2:
The discharge passageway is nested within the discharge chamber structure. The tubular member with holes is positioned inside the discharge chamber, utilizing the existing spatial arrangement to achieve noise control without increasing the overall compressor envelope
3Object-affected harmful factors
If channels linking the muffler and compressor are designed, then noise control is achieved, but large flow loss occurs
Solution Approach 1:
The discharge passageway is designed with optimized local geometry including smooth transitions and specific curvature radii. The tubular member features holes with specific diameter and spacing patterns that minimize flow resistance while effectively reducing noise, achieving local optimization of both flow and acoustic properties
Solution Approach 2:
The system uses specific geometric parameters (curvature radius ratios, hole diameters, hole spacing, passageway cross-sectional areas) to optimize the balance between flow efficiency and noise reduction. By carefully selecting these parameters, the design achieves minimal flow loss while maintaining effective noise control
4Loss of energy
If the combined cross-sectional area of holes is made substantially equal to the discharge passageway area, then flow loss is minimized, but NVH reduction effectiveness must be maintained
Solution Approach 1:
The design uses specific parameter relationships (hole diameter to passageway diameter ratio, number of holes, spacing patterns) to achieve the dual objective. The combined hole area is substantially equal to the passageway area to minimize flow loss, while the distributed hole pattern and spacing create effective noise reduction through turbulence and pressure equalization
Solution Approach 2:
The holes are distributed around the tubular member with specific spacing patterns that create local flow disturbances beneficial for noise reduction. The non-uniform or equidistant spacing patterns create localized effects that reduce NVH while the total area constraint maintains flow efficiency
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
The solution effectively reduces NVH without increasing the compressor's size or inducing flow loss, maintaining over 80% of compressor performance with minimal weight addition, by tuning the hole configuration to specific pulsation frequencies and amplitudes.
Implementation Method 1
The plurality of holes fluidically connecting the discharge chamber and the discharge passageway... The higher pressure fluid in the discharge chamber has pulsations... reducing pressure pulsations and NVH
Data Source
AI summary
A rear housing for a compressor reduces NVH without increasing the overall size of the compressor or inducing flow loss. Generally, the compressor includes a cylinder block receiving lower pressure fluid from the rear housing and providing higher pressure fluid back to the rear housing. The rear housing includes an annular outer wall and an annular inner wall defining a suction chamber and a discharge chamber. An inlet is in fluid communication with the suction chamber. An outlet is in fluid communication with the discharge chamber. The outlet includes a discharge passageway having a tubular member projecting into the discharge chamber. The tubular member is defined by a side wall and a closed end wall. The side wall includes a plurality of holes fluidically connecting the discharge chamber and the discharge passageway.