1. Technical Field
The present disclosure relates to the technical field of a scroll compressor, and more particularly to a self-sealing mechanism for assisting axial sealing of an orbiting scroll through dynamic oil pressure.
2. Related Art
The working principle of a scroll compressor is that: a motor rotor rotates and drives an eccentric shaft at an output end of a main shaft, so as to drive an orbiting scroll, and restricted by a rotation prevention member. The orbiting scroll performs an engaging movement of revolution rather than rotation relative to a fixed scroll, and performs volume-changing operations such as suction, compression, and discharge on a working fluid (for example, a refrigerant) in the above movement manner.
If the scroll compressor is expected to maintain a high working efficiency, a desirable sealing condition must be maintained between the fixed scroll and the orbiting scroll. Leakage during the operation of the scroll compressor is mainly caused by changes of the clearance between the orbiting scroll and the fixed scroll.
For a scroll compressor using HFC refrigerant, the clearance between a top end of an orbiting scroll blade and a bottom plate of the fixed scroll needs to be maintained at 3 to 10 μm, so as to allow a sealing film formed by a lubricating oil film to maintain a sealing effect. In contrast, for a scroll compressor using environmental in noxious refrigerant—CO2, since the CO2 refrigerant has a surface cleaning feature, and the operating pressure of the CO2 refrigerant compressor is about 3 to 4 times as much as that of the HFC refrigerant, the lubricating oil must be continuously fed to positions between the orbiting scroll and the fixed scroll, so that the lubricating effect is maintained even when the clearance between the orbiting scroll and the fixed scroll is below 3 μm, thereby avoiding the abrasion.
Moreover, no matter which type of refrigerant is used by the compressor, due to the mutual solubility of the lubricating oil and the refrigerant, extra lubricating oil must be fed periodically, so as to ensure the constant amount of the lubricating oil in the compressor.
A common axial sealing mechanism for the scroll compressor is to provide an axial pressure during the operation of the scroll compressor, so as to achieve the axial sealing effect between the orbiting scroll and the fixed scroll. For example, the lubricating oil is supplied using an oil pump, and is filled into a back-pressure chamber formed between a back side of the orbiting scroll and the frame. Since the compressor body is filled up with a high-pressure refrigerant therein, the pressure of the high-pressure refrigerant is transmitted into the back-pressure chamber, so that an axial pushing force against the orbiting scroll is formed and pushing the orbiting scroll towards the fixed scroll, so as to eliminate the axial clearance there-between, thereby achieving a desirable sealing effect.
The axial sealing force cannot be generated unless the pressure of the back-pressure chamber is greater than a scroll separating force generated during compression of the working fluid, and the sealing force cannot be too large, so as to avoid excessively pushing the orbiting scroll towards the fixed scroll and cause the top portion of the orbiting scroll blade to contact with the bottom plate of the fixed scroll, resulting in unnecessary axial friction loss. On the contrary, if the axial sealing force is too small, the orbiting scroll may be capsized, thereby causing separation of the scrolls and thus resulting in leakage.