| 摘要 |
<p>PURPOSE: To improve compression efficiency by providing a check valve on a discharge port provided in the neighbourhood of a central part of a fixed spiral vane part and forming a valve seat part of this check valve in a recessed part of roughly the same shape as the check valve at height larger than lift quantity of the check valve. CONSTITUTION: Gas compressed in a compression working space 10 pushes and opens a check valve 23 from a discharge port 22 formed on a fixed spiral vane part 4 and it is discharged to a high pressure chamber 24 of a discharge cavity. A valve seat part of the check valve 23 is formed in a recessed part 31 of roughly the same shape as the check valve 23 and at height larger than lift quantity 30 of the check valve 23. Consequently, when a back flow phenomenon of gas to flow in the compression working space 10 from the high compression chamber 24 of the discharge cavity takes place due to closing delay of the check valve 23, back flow gas comes to pass a narrow clearance part between the side wall of the recessed part 31 of roughly the same shape as the check valve 23 and the check valve 23, back flow high pressure gas is restrained by the amount of passage resistance to be increased, and deterioration of compression efficiency for re-expansion is reduced.</p> |
