GB2427258A

GB2427258A - Electromechanical device of missile seeker head

Info

Publication number: GB2427258A
Application number: GB0610685A
Authority: GB
Inventors: Hagen Kempas; Klaus Fischer
Original assignee: Diehl BGT Defence GmbH and Co KG
Current assignee: Diehl BGT Defence GmbH and Co KG
Priority date: 2005-06-17
Filing date: 2006-05-31
Publication date: 2006-12-20
Anticipated expiration: 2026-05-31
Also published as: DE102005028248C5; GB0610685D0; FR2894341B1; DE102005028248A1; FR2894341A1; DE102005028248B4; GB2427258B

Abstract

The invention relates to an electromechanical device 4 comprising an element, in particular a mirror 10, which is rotatable about at least a first and a second axis of rotation 24, 26; a supporting structure 16; a first holder 20 which is rotatable relative to the supporting structure 16 about the first axis of rotation 24; a second holder 22 which is supported by the first holder 20 and carries the element; and an actuator 34 which acts upon the supporting structure 16 and the second holder 22 for the purpose of moving said second holder 22. To achieve a flat structural form of the electromechanical device 4 perpendicular to the axes of rotation 24, 26, it is proposed that the electromechanical device 4 has an additional actuator 28 which acts on the supporting structure 16 and the first holder 20 for the purpose of moving said first holder 20.

Description

Electromechanical device having an element which is rotatable about at

least a first and a second axis of rotation.

The invention is based on an electromechanical device which comprises an element, in particular a mirror, which is rotatable about at least a first and a second axis of rotation, as well as comprising a supporting structure, a first holder which is rotatable relative to said supporting structure about the first axis of rotation, a second holder which is supported by the first holder and carries the element, and an actuator which acts upon the supporting structure and the second holder for the purpose of moving said second holder.

DE 103 13 136 Al discloses a seeker head with a pitching/yawing internal gimbal system, in which the internal holder of the gimbal system is moved directly by actuators acting on a supporting structure and rotating the internal holder about two axes of rotation. Consequently, actuators on the external or internal holder of the gimbal system can be dispensed with and the gimbal system can have a lightweight construction. Such an internal gimbal system does, however, involve the disadvantage that it takes up a relatively large amount of space perpendicular to the two axes of rotation.

It is the objective of the present invention to propose an electromechanical device having an element which is rotatable about at least a first and a second axis of rotation and which has a flat construction, particularly in respect of its structure perpendicular to the two axes of rotation.

This objective is achieved by a device of the above-mentioned type which, according to the invention, involves an additional actuator which acts on the supporting structure and first holder for the purpose of moving said first holder. The additional actuator acting on the supporting structure and first holder can be disposed along, or in the vicinity of, one of the axes of rotation, thus resulting in a saving in installation space perpendicular to this axis of rotation. Ihanks to the fact that the first actuator acts directly on the supporting structure and second holder, the advantage of low weight in respect of the internal holder can still apply, for which reason this electromechanical device can also be lightweight in structure.

It is advantageous if the first holder is an external frame of a gimbal system. The additional actuator moving this external frame can have its relatively heavy stator fixed so as to be structurally rigid, in which case the external frame forms the rotor. Due to the predominantly structurally rigid arrangement of the additional actuator for movement of the external frame, the movable portion of the device can be lightweight and consequently very dynamic in design. The second holder is advantageously an internal frame of a gimbal system. The element may be an optical element, for example a laser or a radar transmitter or receiver, as a result of which it is possible to obtain a very dynamic and compact optical system. The element is advantageously a mirror.

This way, the angle of movement of a beam path relative to the angle of movement of the mirror can be doubled, as a result of which the movements of the second holder can be kept to a minimum and the device can be very dynamic in design. The mirror usefully lines up a beam path on an additional and, in particular, structurally rigid optical element which is movable relative to the second holder.

in an advantageous embodiment of the invention, the electromechanical device involves a detector with structurally rigid mounting, the element lining up a beam path on said detector. Due to the structurally rigid mounting of the detector, movement of the detector can be dispensed with and the movable parts of the electromechanical device can be made very lightweight. The above-described doubling of the angle of movement of the beam path can be achieved by alignment of the beam path on the structurally rigid detector via the movable element.

A compact construction of the electromechanical device can be achieved in that the two holders fonn an external gimbal system. The element, for example a mirror, does not have to be formed as an annular mirror, but can be located compactly inside the holder.

Due to the overhung mounting of at least one of the holders, there can also be a saving in terms of installation space. Owing to the omission of one of the bearings, the remaining bearing must of course be made relatively stable; however less installation space is needed for this than for two bearings. It is advantageous if at least one of the holders is a forked holder. This also contributes towards the compact design of the device. The two "fork arms" of the forked holder advantageously carry bearings, which specifically support the other holder. The first or the second holder can take the form of a forked holder, the most compact design in terms of installation space being obtained, however, if both holders are forked holders.

In a further embodiment of the invention, it is proposed that the actuator has one winding, which is provided for the purpose of moving the second holder in two opposite directions from a central position. Thus, the second holder can be moved in both directions about the axis of rotation by means of a single winding, as a result of which the second holder can be very lightweight in design.

The actuator advantageously comprises one winding for moving the second holder, and magnetic pole pairs each having two magnets forming an air gap between them, the winding being disposed so as to be movable in the air gaps and the air gaps being free of elements for fixing the winding to the second holder. A low inductance of the components disposed in the air gap can be achieved, as well as a low distortion of the power acting on the winding as a result of inductive components in the air gap.

Irrespective of the relative speed of magnets and winding, the force on the winding can always be kept proportional to the current.

The first actuator advantageously has a plurality of magnetic pole pairs acting on a multiphase winding. Torques can particularly easily be exerted in opposite directions on the winding owing to the magnetic pole pairs which, particularly relative to the axis of rotation of the second holder, are disposed so as to have subtractive polarity. A compact and predominantly structurally rigid arrangement of the first actuator can be achieved if this has a winding and a magnet holder passing through said winding.

A stable mounting of at least one of the holders can be achieved if at least one of the holders is carried by a duplex bearing. In this case, the holder is supported at one or two points involving two bearings disposed so as to be adjacent to one another. The duplex bearing is advantageously braced in X direction. A stable mounting can be achieved - especially with two points of support - without it being necessary to accept the disadvantages of static redundancy. In the case of an overhung mounting of one of the holders, the duplex bearing is advantageously braced in 0 direction, as a result of which a high rigidity of the mounting can be achieved.

The electromechanical device is advantageously disposed in a seeker head of a missile, the supporting structure being firmly attached to the missile casing. A seeker head can be produced which can be guided with great precision to a target due to a high motional dynamic of the device.

Drawings Further advantages will become apparent from the following description of the drawings, which illustrate a working example of the invention. The drawings, the description and the claims include numerous features in combination. The person skilled in the art will use Lully consider the features individually as well as combine them to form additional practical combinations.

The drawings are as follows: Fig. 1 shows a head of a missile with a schematically represented electromechanical device with two mirrors and a detector, Fig. 2 shows a perspective representation of the electromechanical device in Fig. 1 without the second mirror and detector, Fig. 3 shows the electromechanical device without mirror, Fig. 4 shows a perspective representation of the electromechanical device from the rear, Fig. 5 shows an illustration of an X-braced duplex bearing, and Fig. 6 shows a section through an alternative stator for movement of the second holder.

Description of the Working Example

A missile 2 with an electromechanical device 4 is schematically represented in Fig. 1.

The electromec1anjca1 device 4 comprises a detector 6, a first mirror 8, a second mirror and a motion mechanism 12 for moving the second mirror 10. Due to the mobility of the second mirror 10, a beam path 14, which is incident on the second mirror 10 from different directions, can be imaged on the detector 6 which is sensitive in the infrared spectral region. In this case, by a mere turning of the mirror 10 through an angle a, a large angle of movement, 13 = 2a, of the beam path can be achieved by a small movement of the mirror 10.

The motion mechanism 12 comprises a supporting structure 16, which precisely in the same way as in the case of the detector 6 - is firmly and immovably attached to the casing 18 of the missile 2. The supporting structure 16 as well as all the elements of the missile 2 or of the electromechanical device 4 which are immovable relative to said structure are thus fixed so as to be structurally rigid.

Figs. 2, 3 and 4 illustrate the electromechanical device 4 without the mirror 8 and detector 6 as viewed in perspective from three different angles, the mirror 10 being represented in Figs. 2 and 4 but omitted in Fig. 3 for the sake of clarity. The motion mechanism 12 comprises a first holder 20 and a second holder 22, which take the form of an external gimbal system. The mirror 10 is firmly attached to the second holder 22 and can be rotated by the external gimbal system relative to the supporting structure 16 about two axes of rotation 24, 26.

For moving the first holder 20 about the axis of rotation 24, the motion mechanism 12 has a first actuator 28 with a stator 30 and a rotor 32. The stator 30 is firmly attached to the supporting structure 16, and the rotor 32 is firmly attached to the first holder 20.

For moving the second holder 22 with the mirror 10, the motion mechanism 12 comprises a second actuator 34, which likewise has a stator 36 and a rotor 38. The stator 36 is attached by a retaining structure 40 (Fig. 1) to the casing 18 of the missile 2 and thus is structurally rigid. It comprises two magnetic pole pairs 42, the polarity of which is indicated in Fig. 3 by "+" and "-". The two magnetic pole pairs 42 produce, in an air gap 44 of the stator 36, magnetic fields which are aligned substantially radially and oppositely relative to the axis of rotation 26.

The rotor 38 of the second actuator 34 involves a winding 46, a part of which is disposed inside the air gap 44. When the winding 46 is acted on by a current flow, then it produces a magnetic field, which cooperates with the magnetic fields of the magnetic pole pairs 42 in such a way that a torque acts on the rotor 38 about the axis of rotation 26. Depending on the current flow through the winding 46, the torque is directed upwards or downwards. A movement of the second holder 22 about the external axis of rotation 24 essentially only gives rise to a displacement of the winding 46 within the magnetic field of the magnetic pole pairs 42 and thus is insignificant. A turning about the internal axis of rotation 26 is not associated with a turning about the external axis of rotation 24.

In Figs. 2 to 4, the rotor 38 is shown in a resting position, in which the winding 46 is disposed so as to be symmetrical relative to the magnetic pole pairs 42. As a result of a current flow through the winding 46, the rotor 38 can thus be swivelled from the resting position in one or other direction about the axis of rotation 26. For holding the magnetic pole pairs 42, the stator 36 comprises a magnet holder 48 in the form of a double fork which passes through the winding 46, its fork arms in each case carrying a magnet of the magnetic pole pairs 42.

The second holder 22 is mounted on two bearings 50. The first holder 20, on the other hand, is only mounted on one bearing 52 and thus is overhung. In order to obtain a compact and lightweight construction of the motion mechanism 12, both holders 20, 22 are designed in the form of forks, the two bearings 50 being located on the fork arms.

The resistance to bending of the fork-shaped second holder 22 is less than the resistance to bending of an annular holder. In order nevertheless to obtain a stable mounting which is not inconsistent with the flexibility of the second holder 22 and yet keeps it stable, a duplex bearing 54 is provided in each case at the bearings 50, this being schematically represented in Fig. 5. The duplex bearing 54 is braced in X direction, as a result of which the lines of force 56 of compressive forces F1 and F2 of the external bearing shells 60 and internal bearing shells - as produced by the duplex bearing 54 - on the bearing balls are disposed symmetrically in the form of an X relative to the bearing journal 58 of the second holder 22. Thus, the duplex bearing 54 has low resistance to bending and a good translatory fixture is achieved without the disadvantages of static redundancy. The X bracing is achieved by the external bearing shells 60 of the duplex bearing 54 being pressed together by means of an internal nut 62.

The bearing 52 between the supporting structure 16 and the first holder 20 is likewise provided with a duplex bearing 64 which, however, is clamped in an 0 bracing, and thus produces high resistance to bending. As a result, the first holder 20 is kept stable despite its overhung mounting. With the 0 bracing - in a similar way to the duplex bearing 54 - the two internal bearing shells are spaced apart and can be pressed towards one another by means of an internal nut, as a result of which lines of force assume a diamond- or 0-shape relative to the axis of rotation 24.

In addition to this tilt-resistant arrangement, the common centre of gravity of all components that are swivellable about the axis of rotation 24 is positioned as close as possible to the duplex bearing 64. In order to achieve this distribution of mass, the first actuator 28 is overhung on the lower side of the bearing.

The angles of rotation of the two holders 20, 22 are determined by optical angle transmitters 66, 68 measuring directly in the respective axes of rotation 24, 26. For structural reasons, the angle transmitter 68 of the internal axis of rotation 26 is only made in the form of a segment corresponding to the required angular range of the holder. Since the angular range of the external axis of rotation 24 is also limited, the electric supply lines can be carried by means of flexible cables to the angle transmitters 66, 68 and also to the winding 46.

A section through an alternative stator 36' on the second holder 22 is shown in Fig. 6.

This stator 36' has a magnet holder 48', which does not pass through the winding but is held together by two cotmecting elements 70 made of nonmetal material, of which only one is shown in Fig. 6. The magnet holder 48' bears a plurality of magnetic pole pairs 42', which in each case between their magnets form an air gap 44' in which a multiphase winding 46' is disposed. Depending on the connection of the phases, the winding 46' is moved up and down over a wide range, a great range of movement of the winding 46 and with it of the second holder 22 being achieved, which is not limited by passage of the magnet holder 48' through the winding 46'. As with the working example shown in Figs. I to 5, the winding 46' is also carried by fastening elements 72 which are disposed outside of the air gap 44'.

Reference Numerals 2 Missile 42, 42' Magnetic pole pair 4 Electromechanical device 44, 44' Air gap 6 Detector 46, 46' Winding 8 Mirror 48, 48' Magnet holder Mirror 50 Bearing 12 Motion mechanism 52 Bearing 14 Beam path 54 Duplex bearing 16 Structure 56 Line of force 18 Casing of missile 58 Bearing journal Holder 60 Bearing shell 22 Holder 62 Internal nut 24 Axis of rotation 64 Duplex bearing 26 Axis of rotation 66 Angle transmitter 28 Actuator 68 Angle transmitter Stator 70 Connecting element 32 Rotor 72 Fastening element 34 Actuator a Angle 36, 36' Stator 13 Angle of movement 38 Rotor F1 Compressive force Retaining structure F2 Compressive force

Claims

Patent C'aims An electromechanical device (4) comprising: an element, in

particular a mirror (10), which is rotatable about at least a first and a second axis of rotation (24, 26); a supporting structure (16); a first holder (20) which is rotatable relative to the supporting structure (16) about the first axis of rotation (24); a second holder (22) carried by the first holder (20) and carrying the element; and an actuator (34) acting on the supporting structure (16) and the second holder (22) for the purpose of moving said second holder (22), characterized by an additional actuator (28) acting on the supporting structure (16) and the first holder (20) for the purpose of moving said first holder (20).
2. An electromechanical device (4) according to Claim 1.

characterized by a detector (6) with a structurally rigid mounting, in which case the element lines up a beam path (14) on the detector (6).
3. An electromechanical device (4) according to Claim 1 or 2, characterized in that the two holders (20, 22) form an external gimbal system.
4. An electromechanical device (4) according to one of the preceding claims, characterized in that at least one of the holders (20, 22) is mounted in an overhung position.
5. An electromechanical device (4) according to one of the preceding claims, characterized in that at least one of the holders (20, 22) is a forked holder.
6. An electromechanical device (4) according to one of the preceding claims, characterized in that the actuator (34) has a winding (46, 46'), which is provided for moving the second holder (22) in two opposite directions from a middle position.
7. An electromechanical device (4) according to one of the preceding claims, characterized in that the actuator (34) has a winding (46, 46'), for the purpose of moving the second holder (22), and magnetic pole pairs (42, 42') each with two magnets which between them form an air gap (44, 44'), the winding (46, 46') being movably located in the air gaps (44, 44') and said air gaps (44, 44') being free of fastening elements (72) for fixing the winding (46, 46') to the second holder (22).
8. An electromechanical device (4) according to one of the preceding claims, characterized in that the actuator (34) has a plurality of magnetic pole pairs (42') acting on a multiphase winding (46').
9. An electromechanical device (4) according to one of the preceding claims, characterized in that the actuator (34) has a winding (46) and a magnet holder (48) passing through said winding (46).
10. An electromechanical device (4) according to one of the preceding claims, characterized in that at least one of the holders (20, 22) is supported by a duplex bearing (54, 64).
11. An electromechanical device (4) according to Claim 10, characterized in that the duplex bearing (54) is braced in X direction.
12. A seeker head of a missile (2) with an electromechanical device (4) according to one of the preceding claims with a missile casing (18) which is firmly attached to the supporting structure (16).
13. An electrochemical device (4) according to any of the preceding claims as substantially described herein with reference to figures 1 to 6 of the drawings.