Patent ID: 7621721

Claim:
A vacuum pumping device for evacuating a chamber (CV), said vacuum pumping device experiencing in use a plurality of different identifiable operating phases, comprising: an oil mechanical pump (P) comprising: a housing ( 1 ) with a suction port ( 3 ) and a discharge port ( 5 ), the housing having a cylindrical chamber ( 7 ) and a rotor ( 9 ) disposed eccentric with respect to said chamber ( 7 ) said rotor having radial vanes ( 11 ), loaded by springs ( 13 ), said housing being equipped with an electric motor (M) for rotating said rotor ( 9 ); an oil bath ( 15 ), with said oil mechanical pump being immersed therein; and an electronic control device (C) for supplying said electric motor (M) with power by a voltage signal S U , said electronic control device (C) comprising: a frequency converter, which controls an excitation frequency F ecc of the voltage signal S U powering said motor as a function of the value of at least a measured current drain I meas of said (M), the variation range of said excitation frequency Fecc being in any case limited in accordance with the upper limiting value for the maximum power P MAX that can be delivered by said electronic control device (C) a different value of said upper limiting value being set for each of said plurality of different identifiable operating phases, and an oil temperature detector ( 17 ) sending to said electronic control device (C) a signal representative of the temperature of said oil bath in the vacuum pump, said plurality of different operating phases being identified in accordance with said signal representative of the temperature of said oil bath, wherein said upper limiting value takes a value P reg during a steady state operation of the pump, and a value P start1 during a cold start phase of the pump, wherein P reg <P start1 , said upper limiting value takes said value P start1 when the temperature of said oil bath is lower than a predetermined limiting value for the temperature of said oil bath.