Angled Step Seal Geometry for Low-Leakage Refrigerant Compressors
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Solution Overview
Problem
Conventional refrigerant compressors experience significant refrigerant leakage due to the design of traditional seals, which affects the efficiency and performance of refrigeration systems, particularly in HVAC chiller systems.
Innovation Solution
The implementation of a step seal design in refrigerant compressors, featuring a rotor and stator configuration with angled teeth and abradable portions, which creates recirculation zones and minimizes leakage by trapping fluid between the moving and stationary components, thereby reducing total leakage by 40-80% compared to conventional seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional seals are used in refrigerant compressors, then the structure is simple and ease of manufacture is improved, but refrigerant leakage increases significantly reducing system efficiency
Solution Approach 1:
The seal is divided into multiple discrete teeth (typically 3-7 teeth) arranged in a circular pattern around the rotor-stator interface. Each tooth creates an individual sealing zone, and the segmented structure allows refrigerant to be trapped in multiple separate cavities rather than one large leakage path. This segmentation dramatically reduces overall refrigerant leakage while maintaining manufacturing simplicity through standard machining processes.
Solution Approach 2:
The seal transitions from a conventional single-plane contact interface to a three-dimensional stepped structure with teeth extending radially outward from the rotor surface. The teeth create multiple radial and axial sealing zones, adding dimensional complexity to the sealing mechanism. This multi-dimensional approach traps refrigerant in cavities formed between teeth and the stator, reducing leakage paths in multiple directions simultaneously.
2Loss of substance
If the gap between rotor and stator is minimized to improve sealing, then refrigerant leakage is reduced, but the risk of mechanical contact and wear increases
Solution Approach 1:
The stator surface is equipped with localized abradable material zones positioned precisely where the rotor teeth make contact or come close during operation. This abradable material (typically a softer alloy or composite) is applied only in the critical sealing regions rather than throughout the entire stator. When minor contact occurs, the abradable material wears away locally to maintain proper clearance, preventing catastrophic failure while preserving the minimal gap needed for effective sealing.
Solution Approach 2:
The abradable material on the stator serves as a pre-positioned sacrificial layer that cushions against potential mechanical contact between the rotor and stator. This cushioning layer is installed beforehand during manufacturing, providing a buffer zone that absorbs minor impacts and vibrations during operation. The abradable material gradually wears to maintain optimal clearance, preventing direct metal-to-metal contact and catastrophic failure while allowing the system to operate reliably with minimal gaps.
3Device complexity
If traditional seal designs are used, then device complexity is low, but refrigerant leakage reduces system efficiency and performance
Solution Approach 1:
The seal is divided into multiple discrete teeth (typically 3-7 teeth) arranged in a circular pattern around the rotor-stator interface. Each tooth creates an individual sealing zone, and the segmented structure allows refrigerant to be trapped in multiple separate cavities rather than one large leakage path. This segmentation dramatically reduces overall refrigerant leakage while maintaining manufacturing simplicity through standard machining processes.
Solution Approach 2:
The step seal structure creates self-regulating flow patterns where refrigerant leakage naturally generates recirculation zones between the teeth. These recirculation zones automatically form due to pressure differentials and fluid dynamics, creating a self-service sealing mechanism that enhances efficiency without requiring external control systems or complex active components. The geometry itself generates the beneficial flow patterns.
Data Source
AI summary
In some aspects, the techniques described herein relate to a refrigerant compressor, including: a stator; a rotor configured to rotate with respect to the stator; and at least one step seal between the rotor and the stator, wherein the step seal includes a first tooth and a second tooth extending from the rotor toward the stator, wherein a downstream surface of the first tooth and an upstream surface of the second tooth are arranged at an angle relative to one another, wherein the angle is less than 90°.