Method for controlling the outlet temperature of an oil injected compressor or vacuum pump and oil injected compressor or vacuum pump implementing such method

A method for controlling an outlet temperature of an oil injected compressor or vacuum pump comprising a compressor or vacuum element provided with a gas inlet, an element outlet, and an oil inlet, said method comprising the steps of:

• measuring an outlet temperature at the element outlet;
• and
• controlling a position of a regulating valve in order to regulate a flow of oil flowing through a cooling unit connected to said oil inlet;
• wherein the step of controlling the position of the regulating valve comprises applying a fuzzy logic algorithm on the measured outlet temperature;
• and
• the method further comprises the step of controlling a speed of a fan cooling the oil flowing through the cooling unit by applying the fuzzy logic algorithm based on the position of the regulating valve,
• wherein the method further comprises the step of measuring an inlet temperature, an inlet pressure at the gas inlet and an outlet pressure at the element outlet,
• wherein the method further comprises the step of maintaining the outlet temperature at approximately a predetermined target value, said predetermined target value being calculated by determining an atmospheric dew point based on the measured inlet temperature, inlet pressure and outlet pressure and an estimated or measured relative humidity of the gas flowing through the gas inlet, and
• wherein the fuzzy logic algorithm comprises the step of determining a first error by subtracting the predetermined target value from a first measured outlet temperature and determining a second error by subtracting the predetermined target value from a subsequent measured outlet temperature.