Patent ID: 7232295

Claim:
A method of tempering a screw type vacuum pump which includes: a pump housing including a pump chamber housing and a gear/motor housing having a gear chamber and a motor chamber, screw rotors mounted in said pump chamber housing and suspended in a cantilevered manner; said screw rotors being equipped with shafts penetrating said gear chamber and said motor chamber, cooling means for cooling the pump; controlling means for controlling the cooling means in dependence of an operational status of the pump; sensing means including a first and a second temperature sensor, the first temperature sensor supplying signals corresponding to the temperature of said pump chamber housing, the second temperature sensor supplying signals corresponding to the temperature of the rotors, said sensors being connected to the controlling means and said controlling means being connected to the cooling means, the method comprising: with the control means controlling the cooling means in dependence of the sensed temperatures of the pump housing and the rotors in such a manner that a width of a gap between the rotors and the pump housing remains essentially constant.