Compressor with capacity control

A compressor, containing a compressor element, and comprising:

• a rotor chamber connected to an inlet pipe and an outlet pipe;
• a reservoir in communication with the outlet pipe;
• a pressure regulating system including an inlet valve associated with the inlet pipe;
• a piston connected to the inlet valve and which is movable in a cylinder to open and close the inlet valve without the use of a spring acting on the piston;
• a bridge bridging said inlet valve and in which, between the inlet pipe and the rotor chamber, are successively mounted a gas stream limiter and a non-return valve which only admits gas into the rotor chamber;
• a gas pipe connecting the reservoir to a part of the bridge situated between the gas stream limiter and the non-return valve;
• and a relief valve associated with said gas pipe, wherein the piston is a double-acting piston which divides the cylinder into first and second closed cylinder chambers;
• the first cylinder chamber, on a first side of the piston facing away from the inlet valve, is connected to a part of the rotor chamber located near the inlet valve upstream the rotor chamber via a first pipe, wherein the connection is always open;
• and on a second side of the piston, the second cylinder chamber is connected to a part of the rotor chamber situated near the inlet valve and to the non-return valve via a second pipe.