Patent ID: 7513761

Claim:
A double-screw compressor for supplying gas to a gas consumer and comprising two interacting rotors for compressing the gas and a toothed gearing, which toothed gearing comprises: a. a housing with two opposite end walls which are made of a first material, b. two parallel gearwheel shafts, which are each connected to one of the rotors and mounted rotatably in the opposite end walls with a nominal center distance, c. two interacting gearwheels which are fixed on a respective gearwheel shaft and made of a second material, each gearwheel having involute teeth corresponding to one another and designed so as, when engagement between teeth on their respective wheels takes place, to form a nominal backlash between the teeth interacting during the engagement when the gearwheel shafts are located at the nominal center distance from one another, and further having a nominal pressure angle, d. the first and second materials having different thermal expansion coefficients, characterized in that each of the gearwheels comprises the same nominal pressure angle which is smaller than 15° in order to minimize the deviation of the actual backlash from the nominal backlash when a center distance deviates from the nominal center distance as a consequence of a change in temperature of one of the parts included in the screw compressor.