Compressor or vacuum pump device, a liquid return system for such a compressor or vacuum pump device and a method for draining liquid from a gearbox of such a compressor or vacuum pump device

A compressor or vacuum pump device with a liquid-injected compressor or vacuum pump element (2),

• which compressor or vacuum pump device (1) further comprises a liquid return system (7), a motor (4) to drive the liquid-injected compressor or vacuum pump element (2), a gearbox (3) provided between the motor (4) and the liquid-injected compressor or vacuum pump element (2), and a liquid separator vessel (5) in fluid connection with an outlet (6) of the liquid-injected compressor or vacuum pump element (2),
• wherein the liquid return system (7) comprises a main body (8) with a chamber provided with an outlet (16) and a first inlet (9),
• wherein the first inlet (9) is in fluid connection with the liquid separator vessel (5) and receives a first compressed gas flow (11) from the liquid separator vessel (5), and
• wherein the outlet (16) is in fluid connection with an injection point (17) of the liquid-injected compressor or vacuum pump element (2),
• wherein the chamber is also provided with a second inlet (12) which is in fluid connection with the gearbox (3) and receives a second fluid flow (15) from the gearbox (3), and
• wherein the chamber is configured to mix the aforementioned first compressed gas flow (11) and a second fluid flow (15) together into a third fluid flow (20), which third fluid flow (20) leaves the chamber via the outlet (16) and is directed via the injection point (17) into the liquid-injected compressor or vacuum pump element (2).