Scroll Fluid Machine Tip Seal Inversion
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Solution Overview
Problem
The stepped scroll compressor experiences significant fluid leakage and stress concentration at the step portions, leading to reduced performance and strength, particularly due to the shape of the groove bottom in the tip seal which can cause clearance issues and potential damage from the inclined wall design.
Innovation Solution
A scroll fluid machine with an inclined portion where the inter-facing surface distance between end plates decreases from the outer to the inner peripheral side, featuring a groove bottom shape with a deepest center portion and a tip seal that protrudes from both sides to minimize clearance, and optionally divided in the spiral direction to accommodate changes in wall height, ensuring effective sealing and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuously inclined portion is provided instead of step portions to reduce fluid leakage and stress concentration, then reliability is improved, but a clearance between the groove bottom center and tip seal bottom center is formed due to the groove shape, causing fluid leakage and performance reduction
Solution Approach 1:
The groove bottom shape is inverted from the conventional deepest-center design to a design where the center portion protrudes upward. This inversion eliminates the clearance problem caused by the semicircular groove shape while maintaining the benefits of the continuously inclined portion for reducing stress concentration and fluid leakage at step portions.
Solution Approach 2:
The tip seal is designed with non-uniform thickness, where the center portion in the width direction protrudes more than the side portions. This local variation in geometry compensates for the groove bottom shape and ensures optimal contact and sealing at the tip seal-groove interface throughout the inclined portion.
2Reliability
If the tip seal shape is changed to follow the inclined portion of the wall, then sealing effectiveness is improved, but the tip seal may deteriorate or be damaged
Solution Approach 1:
Instead of changing the entire tip seal shape to follow the inclined wall, only the center portion in the width direction is made to protrude. This partial modification provides sufficient sealing effectiveness at the critical center contact region while avoiding excessive deformation that would damage the tip seal.
3Ease of manufacture
If a groove portion is formed with the deepest center to accommodate the inclined portion, then manufacturing is simplified, but a fluid leakage clearance is created between the groove bottom center and tip seal bottom center
Solution Approach 1:
The groove bottom geometry is inverted from the conventional deepest-center configuration to a configuration where the center portion protrudes upward. This inversion maintains ease of manufacture using standard cutting tools while eliminating the fluid leakage clearance by ensuring the tip seal center contacts the groove bottom center without gap.
Data Source
AI summary
The present invention improves performance of a scroll fluid machine by effectively exhibiting a function of a tip seal installed at a tooth tip of a wall body even when a continuous slope is provided to the wall body. A slope in which the distance between opposing surfaces of opposing end plates continuously reduces from the outer peripheral surface toward the inner peripheral surface is provided, and a tip seal (7) that comes into contact with an opposing tooth bottom so as to seal a fluid is provided to a tip seal groove (3d) formed at a tooth tip of a wall body (3b) corresponding to the slope. A groove bottom (3d1) of the tip seal groove (3d) is formed into a shape in which the center portion (3d2) in the groove width direction deepest. The tip seal (7) is formed such that the center portion (7a1), in the width direction, of the bottom (7a) of the tip seal (7) facing the groove bottom (3d1) projects farther than both side portions (7a2).