Abstract: A method for determining the fatigue of the pump rotor of a gas turbopump comprises the following method steps: continuous determination of the rotational speed (n) of the pump rotor, determination of the local rotational speed maxima and minima of a temporal rotational speed profile under consideration, association of the rotational speed maxima and minima with each other to form pairs, determination of a pair fatigue value (L) for each of the rotational speed pairs, and accumulation of all pair fatigue values (L) to form a total fatigue value (Ltot). In this manner it is possible to determine the cyclic stress for the pump rotor of a vacuum pump and to include it in the calculation of a total fatigue value.

Abstract: A method for determining the fatigue of the pump rotor of a gas turbopump comprises the following method steps: continuous determination of the rotational speed (n) of the pump rotor, determination of the local rotational speed maxima and minima of a temporal rotational speed profile under consideration, association of the rotational speed maxima and minima with each other to form pairs, determination of a pair fatigue value (L) for each of the rotational speed pairs, and accumulation of all pair fatigue values (L) to form a total fatigue value (Ltot). In this manner it is possible to determine the cyclic stress for the pump rotor of a vacuum pump and to include it in the calculation of a total fatigue value.

Abstract: A turbomolecular pump (10) comprises a stator (12, 18), a pump rotor (20) a motor (28) for driving the pump rotor and a control device (42). The control device (42) controls the motor output power such that the motor output power does not exceed a permissible maximum motor output power. On the stator side of the turbomolecular pump (10), temperature sensors (32–38) for measuring the stator temperature are arranged. The control device (42) comprises a maximum output power detecting device (50) that determines the permissible maximum motor output power in dependence on the measured stator temperature. Thus, the permissible maximum motor output power is not set to a constant value but always fixed in dependence on the current, measured stator temperature. Thereby, the capacity of the motor can be fully utilized as long as the measured stator temperature lies below a maximum value.

Abstract: A turbomolecular pump (10) comprises a stator, a pump rotor, a motor (28) for driving the pump rotor and a control device (42). The control device (42) controls the motor output power such that the motor output power does not exceed a permissible maximum motor output power. On the stator side of the turbomolecular pump (10), temperature sensors (32-38) for measuring the stator temperature are arranged. The control device (42) comprises a maximum output power detecting device (50) determining the permissible maximum motor output power in dependence on the measured stator temperature. Thus, the permissible maximum motor output power is not set to a constant value but always fixed in dependence on the stator temperature. Thereby, the capacity of the motor can be fully utilized as long as the measured stator temperature lies below a maximum value.