Scroll compressor with back pressure regulation mechanism

Abstract

A back pressure regulation mechanism is incorporated in a scroll compressor. The compressor includes a fixed scroll and a spacing member fixed inside a casing to define a high pressure chamber behind the fixed scroll. The back pressure regulation mechanism includes a boss formed on the fixed scroll and extending through the spacing member into the high pressure chamber whereby a first force caused by pressure difference acts upon the boss and thus the fixed scroll, a plurality of bores defined in the spacing member, each bore being in communication with the high pressure chamber and the fixed scroll, and a back pressure regulation device accommodated in each bore and including a pin received in the bore and movable between upper and lower limit positions, a washer engaging the fixed scroll and a disk spring arranged between the pin and the washer. A second force caused by the pressure difference acts upon the pin and is transmitted to the fixed scroll via the disk spring and the washer. The second force is proportional to the pressure difference when the pin is moving from the upper limit position to the lower limit position and the second force becomes a constant when the pin reaches the lower limit position. The first and second forces together provide a back pressure to the fixed scroll.