Scroll Compressor, Tip seal, Leakage
Scroll compressors are widely used in room air conditioning cycles, package air conditioning cycles, refrigeration, water heater and automobile air conditioning cycles as well as air compressors, helium compressors and vacuum pump. There are two main leakage paths in a compression chamber formed by a fixed scroll and an orbiting scroll. One is the leakage path through a radial clearance between the wraps of fixed and orbiting scroll. The leakage through the radial clearance is prevented by pressing the orbiting scroll radially against the fixed scroll by a mechanism such as a compliance mechanism. Oil inside the compression chamber also has the sealing effect and reduces the leakage through the radial clearance. Another leakage path is an axial clearance which is the clearance between a tip of the scroll wrap and a base plate. A tip seal is often used to prevent the leakage through the axial clearance. Although there have been many studies on the tip seal, the seal mechanism of the tip seal is not thoroughly clarified yet, and the influence of design parameters on efficiency of the tip seal is unclear. In addition, the relationship between the sealing effect and a frictional loss of the tip seal is also not validated well. In this study, a test apparatus which can evaluate the sealing effect and the frictional loss of the tip seal simultaneously is developed. The influence of several design parameters on the sealing effect and the frictional loss is examined with the test apparatus. By measuring pressure distribution around the tip seal in a tip seal groove, the sealing mechanism of the tip seal is clarified and a design guideline of the tip seal groove is obtained.