Drive of a tail rotor of a helicopter

Abstract

The invention relates to a drive (1) of a tail rotor (12) of a helicopter (10) by a permanently excited transversal flux machine in duplex arrangement in such a way that between two stators (4), which each have a toroidal winding system (8), there is arranged a disc-shaped impeller (5), which has permanent magnets (15) and on the outer circumference of which propeller blades (14) of the tail rotor (12) are arranged.

Claims

1. A tail rotor of a helicopter having an axis and comprising: a drive constructed in the form of a permanently excited transverse flux machine in a duplex arrangement and including two hollow stators which are spaced from one another in an axial direction to form a gap therebetween and each extending concentrically about the axis of the tail rotor and a single disk-shaped rotor which is arranged in the gap axially between the two stators and also extends concentrically about the axis of the tail rotor and is symmetrical relative to the axis, said disc-shaped rotor having radially extending permanent magnets arranged on its opposite axial sides facing said stators, each said stator having a ring winding system arranged concentrically about the axis of the tail rotor with a plurality of ring windings of each ring winding system arranged inside each said stator radially one above the other relative to the axis of the tail rotor and axially facing the radially extending permanent magnets of the rotor; propeller blades arranged on a radially outer perimeter of the disk-shaped rotor on diametrically opposite sides of the latter; a radial bearing assembly arranged radially inwardly of the disc-shaped rotor and radially inside said stators and supporting the disc-shaped rotor for rotation about the axis; cans provided in each of the stators and accommodating the ring winding systems the stators in one-to-one correspondence, wherein said cans are arranged on two opposite sides of said single disc-shaped rotor and are open axially towards each other and towards the permanent magnets and each of said cans in each of said stators has a plurality of partitions spaced from each other in the radial direction and forming a plurality of radially spaced recesses which are axially open towards the radially extending permanent magnets of opposite axial sides of the rotor and in which the ring winding of the ring winding systems are received and exposed towards the permanent magnets, wherein the cans accommodating the ring winding systems facing a central element of the disc-shaped rotor from its both axial sides, the partitions of the cans are located exactly opposite to one another on same radii, and recesses of the cans are located exactly opposite to one another on same radii; and a supporting element providing a secure enclosure of components including the stators, the permanent magnets, the central element of the rotor between the stators, and the air gap and having a dimension in a direction of the axis which is greater than a total dimension in the direction of the axis of all the components together, wherein the tail rotor is configured so that its aerodynamics are designed such that air cooling of the gap between the stators which is an air gap comes about due to a venturi effect.

2. The tail rotor of claim 1, wherein the permanent magnets are laminated.

3. The tail rotor of claim 1, wherein at least the ring winding systems are oil-cooled.

4. The tail rotor of claim 1, further comprising a common axial bearing assembly which jointly with the radial bearing assembly provides support for the drive and the tail rotor, wherein the axial bearing assembly of the tail rotor is a regulated magnetic axial bearing mounting which is realized by the ring winding systems of the stators with a zero phase-sequence system of a three-phase a.c. system of the ring winding systems of the stators.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention together with advantageous embodiments of the invention are to be deduced from the attached drawing; this shows:

(2) FIG. 1 a helicopter,

(3) FIG. 2 a tail rotor drive in the helicopter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(4) FIG. 1 shows a diagram of the principle of a helicopter 10 with a main rotor 11 and a tail rotor 12, shown by way of example, which is arranged on a tail boom 13. Here, the tail rotor, which is attached in the tail boom 13 of the helicopter 10 outside the sweep of the main rotor 11, produces a horizontal thrust to counteract the turning of the body about the main axis. Apart from torque compensation, the tail rotor 12 is also used to steer the helicopter 10 about its main axis, that is for right/left turns.

(5) FIG. 2 shows a drive 1 in accordance with the invention, for a tail rotor 12 on a helicopter 10, which uses a permanently excited transverse flux machine in a duplex arrangement. Here, both on the left and on the right of a rotor 5 there is a stator 4 with ring windings 8 which are arranged concentrically about an axis 17. The rotor 5 is mounted on this axis 17 by means of radial bearings 3 in such a way that it can rotate. On the radially outer edge of the disk-shaped rotor 5, a supporting structure 2 is provided, on which are arranged the propeller blades 14 of the tail rotor 12. In this form of embodiment, the propeller blades 14 are here arranged as radial extensions of the disk-shaped rotor 5.

(6) Also encompassed by the general inventive thinking are embodiments which provide some other constructional arrangement of the propeller blades 14, e.g. on the outer surface of a pan-shaped embodiment of the supporting structure 2.

(7) The at least one radial bearing 3 only undertakes the radial mounting and accepts the radial forces, while an axial bearing mounting of the rotor 5 is effected by the two ring winding systems 8, preferably three-phase a.c. ring winding systems, in the stator 4 concerned. There is thus a magnetic axial bearing mounting. In this form of embodiment, the magnetic return path of the transverse flux motor is used for this regulated magnetic bearing. The two zero phase-sequence systems of the three-phase a.c. winding systems are regulated independently of each other in order, as appropriate, to hold or provide a bearing for the rotor 5, and hence ultimately the tail rotor 12, axially in its prescribed position.

(8) The field lines 7, which are shown in principle, are excited by the zero phase-sequence system concerned.

(9) By the weighting of the left and right zero phase-sequence current it is possible to control the attractive force in terms of its magnitude and signthat is to the left or the right.

(10) In a tail rotor 12, aerodynamic propeller forces arise mainly in an axial direction, and these are now absorbed by the magnetic axial bearing mounting.

(11) The rotor 5 with its permanent magnets 15 arranged on a disk moves in air in the air gap between the two stators 4, and is air-cooled. In one form of embodiment, the eddy current losses of the permanent magnets 15 arranged on the rotor 5 are dissipated by external ventilation.

(12) In a further particularly advantageous form of embodiment, the aerodynamics of the tail rotor 12 are designed such that air-cooling of the air gap 6 comes about due to the venturi effect. This means that it is not necessary to provide additional external fans, which on the one hand would need to be monitored for their functioning and on the other hand would unnecessarily increase the weight of the helicopter 10.

(13) However, in order to reduce the eddy current losses, the permanent magnets 15 are made in laminated form.

(14) Advantageously, the drive 1 and the tail rotor 12 will now have common radial and axial bearing mountings, and a gearbox and/or additional bearing units in the region of the tail rotor can be forgone.

(15) In order to further reduce the weight of the helicopter, the stators 4 will advantageously be provided with metallic laminates.

(16) In order to further increase the utilization of the drive 1 for the tail rotor 12, the ring windings 8 will have oil-cooling. In this case, a can 9 encloses a ring winding which runs concentrically, that is a phase of a stator 4 or the entire ring winding system of the stator 4 concerned. This is shown in principle in the lower half of FIG. 2 on the left-hand stator 4. By this means, the heat losses of the winding system are dissipated.

(17) It is also possible for an entire stator 4 with its yoke, in particular iron core stack, and its winding system to be located in an oil bath.

(18) The arrangement described for a drive 1 for a tail rotor 12 is thus constructed as a permanently excited transverse flux motor in a duplex arrangement, for a helicopter with a power of 234 kW at approx. 3600 l/min, with the drive 1 for the tail rotor 12 having an external diameter 16 of approx. 3500 mm, which corresponds to the internal diameter of the tail rotor 12.