A vacuum pump comprises: a rotary body including a rotor blade and a rotor shaft; a case rotatably housing the rotary body; a motor configured to drive the rotor shaft of the rotary body; a bearing arranged at an end portion of the rotor shaft; and at least three balance correction portions including a first balance correction portion provided on one end side of the rotary body in an axial direction, a second balance correction portion provided on the other end side of the rotary body in the axial direction, and a third balance correction portion provided between the first balance correction portion and the second balance correction portion. Balance correction by an n-plane method, where n 3, is available such that any of the three balance correction portions is accessible from an outside of the case.

A fan apparatus comprises a stator unit, a rotor unit comprising an impeller, and a casing that houses the stator unit and the rotor unit. The casing comprise a side wall portion that surrounds a periphery of the impeller, a base portion that holds the stator unit and the rotor unit, and a plurality of connection portions that connect the side wall portion and the base portion. The casing is formed by at least two members including a first member and a second member coupled to the first member. The first member includes at least one of the connection portions and at least part of the base portion, and the second member includes at least one of the connection portions.

A windage shield system comprises first and second hollow cylindrical elements, the longitudinal axes of the outer and inner surfaces of each element being parallel and mutually displaced. The elements are mounted to the downstream end of a fan disc such that the longitudinal axes of the inner surface of the first element and the outer surface of the second element coincide with the rotational axis of the disc. The centres of mass of the elements are mountable with azimuthal offsets .sub.1, .sub.2 with respect to the fan disc, each being selectable from a large number of values in the range 0 to 360. The first element is integral with a windage shield. The system allows a fan disc to be provided with a windage shield and the resulting assembly to be balanced at its rear plane in cases where access to the rear of the fan disc is difficult.

Blades (20a to 20c) of a propeller fan (10) have different circumferential pitches 1, 2, and 3. The blades (20a to 20c) have different masses so that the center of gravity of the propeller fan (10) is positioned on a rotational center axis (11) of the propeller fan (10). Blade body portions (42c) of the blades (20a to 20c) have different thicknesses. In contrast, camber lines of the blades (20a to 20c) in blade cross section have the same shape, projections of the blades (20a to 20c) on a plane perpendicular to the rotational center axis (11) of the propeller fan (10) have the same shape, and leading edge portions (41a to 41c) of the blades (20a to 20c) have the same shape. As a result, a propeller fan (10) having reduced noise and vibrations can be achieved.

An electrically driven pump is provided, which includes a rotor assembly. The rotor assembly includes an impeller, a rotor and a shaft sleeve assembly. The impeller is arranged on one end of a shaft sleeve, and the rotor is arranged on another end of the shaft sleeve away from the end on which the impeller is mounted. The rotor includes a rotor core, a permanent magnet and a shield. The permanent magnet is arranged around an outer peripheral surface of the rotor core and fits the outer peripheral surface of the rotor core. The shield is fixed to the shaft sleeve, and an accommodating portion configured to accommodate the rotor core and the permanent magnet is formed between the shield and the shaft sleeve. The electrically driven pump has a simple structure and is easy to manufacture.

A rotational body 1 includes a rotational shaft 2, an impeller 3, and a nut 6. The impeller includes a hub portion 4 having a peripheral surface 4s inclined to the axial direction of the rotational shaft and having an insert hole 4h in which the rotational shaft is inserted, and a blade portion 5. At least one of the rotational shaft or the insert hole of the hub portion has an interference fit portion 10 for fit between the rotational shaft and the impeller, where the outside diameter of the rotational shaft is larger than the inside diameter of the insert hole of the hub portion. The interference fit portion is formed in a region which does not include the largest outside diameter portion 4B where the hub portion has a largest outside diameter, with the rotational shaft and the impeller mating with each other.

A gas turbine engine rotor including a disc adapted to be mounted for rotation about an axis, the disc including an annular balancing flange integrally connected thereto, the balancing flange having a first radial dimension around a first arc angle and a second radial dimension greater than the first radial dimension around a second arc angle, the second arc angle corresponding to 360 minus the first arc angle, the second arc angle being less than 180 degrees, the balancing flange around the second arc angle defining a protuberance, the protuberance being defined through machining of the balancing flange, the protuberance compensating for an unbalance of the rotor.

A turbomolecular pump is provided. In one arrangement, a stator stack and rotor stack have corresponding conical or frustum shapes that allow for adjusting the clearance between the stator vanes and rotor vanes of the pump to provide adjustable compression ratios and/or to adjust clearances. In another arrangement, the actuator or drive mechanism of the pump is formed from coils attached to the upper stage of rotor vanes which are controlled to interact with a plurality of stationary magnets attached to the housing of the pump to rotate the stator stack. In another arrangement, a control system of the pump utilizes the coils of the rotor drive to dynamically balance the pump during operation.

An example method of balancing a shaft includes inserting a balancing insert into one of a plurality of cavities. The plurality of cavities are radially inside an outermost surface of the shaft.

A method of reducing loads in a rotor assembly during an imbalance condition, a shape memory alloy recoupler device, and a hybrid bearing support system are provided. The hybrid bearing support system includes a shaft extension fixedly coupled to a rotatable member at a radially inner end of the shaft extension, a radially outer end of said shaft extension fixedly coupled to a rotatable race of a bearing supporting the rotatable member, and a recoupler device formed of a shape memory alloy (SMA) material coupled in parallel with at least a portion of said shaft extension between the radially inner end and the radially outer end.