2202G1JE-DA-M-N_2010.01.
2 Configuration and Specification of Compressor
Reciprocating Compressor M Series 2.1 Configuration of Compressor
2-6
When the solenoid valve is not energized (OFF), oil supply from the pump is stopped. At the
same time, the oil discharge route opens and the oil in the unloader cylinder is discharged. Then,
the pressure decreases. The pressure which presses the unloader piston decreases, and the piston
is pressed back by the force of unloader device spring. Then, the piston becomes unload.
2.1.4 Unloader Mechanism
Fig. 2-12 Unloader mechanism
The capacity control (unloader) mechanism controls the operation of suction valve using unloader piston. By
controlling the operation of suction valve, it changes the number of cylinder which compresses gas to change the
suction capacity (performance).
The details of mechanism are as below.
The suction valve (suction plate valve) are attached on the top of cylinder sleeve (flange). Gas enters
into the cylinder from the passage between the external and internal seats. A lift pin which moves
upward and downward is installed in the gas passage at the center of these seats. The top side of lift pin
contacts the suction valve. The bottom of lift pin is on the inclined surface of cam ring on the cylinder
which rotates on the diameter of cylinder sleeve. This cylinder cam ring is rotated by the rod which is
moved by the unloader piston. This rotation moves the lift pin upward and downward.
If the lift pin is moved downward to below the seats surface, the suction valve (suction plate valve)
operates depending on the pressure difference. However, when the lift pin pushes up and retains the
suction valve by the rotation of cam ring, the suction valve does not close even if pressure difference is
generated. In this state, even though the piston moves upward and downward in the cylinder, the gas
only passes in and out from the suction opening. Due to this, the pressure does not increase and the gas
is not discharged. At this time, this cylinder is in unload state. As described above, this mechanism
controls the capacity by changing the number of cylinder which compresses gas.
The cam ring is moved by oil pressure and the spring. If the unloader piston is not pressurized by oil, it
becomes unload by the force of spring. Therefore, the capacity can be controlled by cutting off the oil
pressure during machine operation. This is performed by a three-way solenoid valve.
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