GB1598506A

GB1598506A - Gyroscope assemblies

Info

Publication number: GB1598506A
Application number: GB7832/78A
Authority: GB
Original assignee: Airbus Group SAS
Current assignee: Airbus Group SAS
Priority date: 1977-03-14
Filing date: 1978-02-28
Publication date: 1981-09-23
Also published as: DE2811448A1; IT1093327B; DE2811448C2; FR2384235B1; FR2384235A1; IT7821129A0

Description

(54) IMPROVEMENTS RELATING TO GYROSCOPE ASSEMBLIES (71) We, SOCIETE NATIONALE IN DUSTRIELLE AEROSPATIALE, S.A. a French Company of 37, boulevard de Montmorency, Paris 16eme, France, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a gyroscope assembly for guiding craft such as missiles which travel through the air and rotate about the axis along which they travel and which also are subject to slight variations in trim or in yaw, and relates more particularly to gyroscope assembly having a very short operating time, associated with a missile-guiding device and intended for furnishing a reference of the vertical.The invention also relates to craft including said gyroscope assemblies.

It is known that, in missiles which rotate in flight and have movable surfaces for guiding or correcting their path, the guide device must be associated with a gyroscope capable of furnishing a reference of the vertical, said reference allowing a correct functioning of the movable surfaces as a function of the path correcting orders furnished by the guide device determining this path (internal or external guiding, independent or ground-controlled, etc ) Gyroscopes associated with the known missile-guiding devices are hung on gimbals, this resulting in these gyroscopes being mechanically complicated and expensive, although they are used for a very short operating time and are not recoverable.

Moreover, their suspensions unsatisfactorily withstand the considerable accelerations, of the order of 10.000 g, to which they are subjected in the missiles. Furthermore, as soon as the frames of the gimbal suspension are no longer in correct position, a parasitic deflection occurs, due to the deceleration of the rotor (or top) of the gyroscope, this defect being aggravated under the effect of the acceleration of the missile. In fact, in these gyroscopes, the rotation of the rotor is not maintained. If the acceleration of the missile is considerable, the anisoelasticity of the gimbal suspension introduces a deflection proportional to the square of the said acceleration, which deflection may become preponderant.Similarly, with considerable acceleration, the roller bearings of the suspensions do not resist well and require, during the phase of maximum acceleration, the assistance of auxiliary members such as stops. However, these members themselves can cause an undesirable, if not prohibiting, side effect.

To remedy these drawbacks, it has been thought to use electrostatic vertical position detectors, which measure the maximum difference of the terrestrial electrostatic field between two points. However, these detectors do not give entire satisfaction as their indications are uncertain due to the instability of said field.

The present invention remedies these drawbacks and to this end relates to a gyroscope whose structure is such that it is mechanically simple, reliable, inexpensive and extremely light (a few tens of grams).

To this end, the invention provides a gyroscope assembly for mounting on a craft which travels through the air and rotates about the axis along which it travels, said gyroscope assembly being for giving a reference of the vertical to said craft, nothwithstanding slight variations in trim and yaw of the craft, and comprising - a sphere for mounting fast with said craft so that one of the diameters of said sphere is parallel to or coincident with the rotation axis of the craft; - an at least substantially toroidal gyroscope rotor disposed concentrically with respect to said sphere and being able to roll on the sphere, said rotor being arranged so that when the sphere is mounted on the craft, the plane of the rotor is inclined by an angle determined with respect to said rotation axis of said craft;; - said rotor having a surface of revolution which is reflecting for a determined radiation, e.g. infrared radiations; - an emitter and a receiver of said radiation for fixing on a portion of said craft so that they are, before the launching of said craft, in a determined relationship with respect to the vertical; - said emitter and receiver and said surface of revolution being for arrangement so that, after launching of said craft when this latter rotates about said axis, said receiver receives, during a small portion of each revolution of said craft, the radiation emitted by said emitter and reflected by said surface of revolution, when said emitter and said receiver occupy, during said portion, a position corresponding to said predetermined relationship with respect to the vertical.

Said angle is preferably close to 45". The rotor may be formed by two side members and a peripheral annular body joined to one another by screwing, due to the cooperation of threads provided respectively on the inner circular face of said annular body and on the peripheral edges of the two side members. Thus, the assembly of the two side members and the assembly of each side member and the annular body are effected simultaneously.

For positioning the side members with respect to each other and with respect to the annular body, it is advantageous if each side member includes a coaxial cylindrical projection, one of the projections interfitting with the other.

A coaxial annular groove is advantageously provided in each of said side members, opposite the sphere, each groove serving as ball race via which the rotor may roll on the sphere.

Due to the structure of preferred form of the gyroscope assembly according to the invention, it is easy to mount the rotor on the sphere. To this end, it suffices to bring the two side members near to said sphere, to introduce the balls in the grooves of the side members, to fit the projections of the side members in one another, then to screw the annular body on the periphery of said side members. Such a structure is simple, reliable and inexpensive.

The sphere of the gyroscope assembly is preferably adapted to be made fast with the craft by means of diametrically opposite pointed rods cooperating with corresponding recesses in said sphere, and lying on an axis of said parallel to or coincident with rotation axis, of the craft.

In the known manner, the gyroscope assembly may be started up by igniting at least one propellant charge placed inside the rotor, so that the combustion gases cause said rotor to rotate. In this case, a toroidal chamber is arranged between the side members and the annular body, which chamber contains at least one propellant charge and one igniting device, the or each igniting device including a firing conducting wire passing through said annular body through a port forming an ejection nozzle for the gases produced by the propellant charge.For two of these firing conductors to be able, likewise in known manner, to lock the rotor of the gyroscope assembly in a determined rest position before it is rotated, it is advantageous if the gyroscope assembly according to the invention comprises at least two diametrically opposite igniting devices, the firing conductors of these igniting devices, passing into the annular body through pairs of gas ejecting ports, diametrically opposite in twos.

As mentioned hereinabove, the gyroscope assembly according to the invention is intended to be mounted in a craft, such as a missile to be associated with the guiding device thereof in order to furnish it with a reference of the vertical. Such a guiding device is well known for such an application and, as, moreover, it does not form part of the invention, it will neither be shown nor described hereinafter. On the other hand, the use of a surface of revolution on the radiation reflecting surface constitutes an important feature of the present invention.

Thus, after the rotor of the gyroscope has been rapidly rotated, the guiding device may receive an impulse via said receiver, each time that, in the course of rotation of the craft, the emitter and the receiver pass through a position identical to their initial position.

Said reflecting surface of revolution is preferably made on the peripheral annular body of the rotor of the gyroscope. Moreover, the emitter and the receiver are for mounting near each other, so that their axes of emission and reception are substantially parallel to the rotation of the craft.

Preferably, the reflecting surface is a convex surface of revolution of which the centre of the axis of curvature thereof lies on the centre of the sphere.

Also according to the invention there is provided a craft which travels through the air and rotates about the axis along which it travels. including a gyroscope assembly as aforesaid.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which; Figure 1 is an axial section, in rest position, of the gyroscope assembly according to the invention; Figure 2 is a diametrical section, along line II-II of Figure 1.

Referring now to the drawings, these Figures show the gyroscope assembly according to the invention which comprises a solid sphere 1 for example made of stainless steel, made fast with a casing 2 which has been shown partially. This casing 2 is fast with a craft (not shown), and contains said gyroscope assembly. The sphere 1 and the casing 2 are connected by means of a pointed rod 3 and a pointed rod 4, diametrically opposite each other with respect to the sphere 1 and cooperating with suitable recesses therein. The axes of rods 3 and 4 are parallel to (or coincident with) the longitudinal and rotation axis of the craft.

On the sphere 1 a rotor, generally referenced at 5, may roll by means of two ball groups 6 and 7. The rotor 5 is approximately in the form of a torus, the sphere 1 being housed in the recess of the torus, concentrically with respect thereto.

The rotor 5 is formed by two side members 8 and 9 and by a peripheral annular body 10. The two side members 8 and 8 are centered with respect to each other by their respective tubular projections 11 and 12 interengaging with an easy fit, whilst the side members 8 and 9 are joined to each other and with the annular body 10 by threads 13 provided on the inner face of said body and on the periphery of said side members.

Each side member 8 and 9 comprises a coaxial annular groove 14 or 15 in which the groups of balls 6 or 7 are respectively housed.

The annular body 10 comprises four peripheral ports 16 diametrically opposite one another in twos and intended to constitute gas ejection nozzles.

In fact, the side member 8, 9 - body 10, assembly determines an inner toric cavity 17 which contains a propellent charge 18 and four igniting devices 19, diametrically opposite one another and constituting a gas generator used for driving said rotor by ejection of gas through said nozzles 16.

The wires 20 activating the igniting devices 19 are connected to a firing device (not shown) by means of the casing 2 to which they are fixed in order to maintain said rotor at an angle a determined with respect to the longitudinal axis of the missile, materialised by the axes of rods 3 and 4.

This angle a has a value of 45 , for example. At the moment of starting the spinning of the rotor 5, which coincides with the departure of the missile, said wires 10 burn and break.

Heat protection elements 21 are inserted between the propellent 18 and the walls of said toric cavity 17.

It will be noted that the tubular projections 11 and 12 form a seal. The annular body 10 of the rotor 5, made of heavy metal, comprises a curved, reflecting surface of revolution 22. The axis of curvation of the reflecting surface is centred on the centre of the sphere 1.

In initial rest postion of the rotor 5, the sectioned part 22 comprises a portion 22a substantially at right angles to the longitudinal axis of the missile.

On a face 23 of the casing 2, at right angles to the axis of the missile, there are arranged an infrared emitter 24 and an infrared receiver 25, side by side and opposite the portion 22a of the surface 22 which is located nearest thereto when the whole is in pre-operation position (rest position).

The conductors 20 pass through the nozzles 16, conical in shape and oriented tangentially so as to drive the rotor in rotation upon ejection of gas. The conductors 20 are connected to a firing device (not shown).

When the gyroscope assembly according to the invention is mounted in a missle, not only the axis of the rods 3 and 4 is disposed parallel to the longitudinal axis of said missle, but the emitter-receiver 24-25 is positioned in predetermined manner with respect to the vertical plane of said missile containing said longitudinal axis.

Upon departure of the missile, the igniting devices 19 are activated by means of the conductors 20.

They trigger off combustion of the charge 18, this producing a gas which is ejected through the nozzles 16.

The rotor 5 is then driven in rotation and its speed increases rapidly up to 20 000 r.p.m. for example, then decreases slowly to the end of the path of said missile. When said missile is launched it simultaneously enters into rotation. The rotor remains substantially parallel to itself by gyroscopic effect, but the casing 2, fast with said missile, rotates about an axis parallel to the axis of rods 3 and 4.

Consequently, the emitter-receiver 24-25, previously activated, moves away from and approaches the reflecting part 22 of the rotor 5, alternately, at each revolution.

The rays emitted by the emitter 24 are reflected by said part 22 towards the receiver 25, but only during a small portion of the revolution of the casing 2 with respect to said rotor, this being so when the emitter and the receiver pass into an angular sector determined with respect to the absolute vertical, located at the departure of the missile or by any other means.

A signal therefore appears at each revolution of autorotation of the missile at the terminals of the receiver 25, when the angular radial position of said missile is determined with respect to the vertical and corresponds to the initial position (shown by Figure 1.).

This signal enables the position of the movable surfaces to be coordinated with respect to the piloting controls.

When the missile undergoes a slight variation in yaw or in trim, the position of the rotor varies slightly, but the section of the reflecting part 22 makes it possible to continue to obtain upon each revolution of the casing 2, a connection by reflection between the emitter 24 and the receiver 25.

In fact, due to its form, said part 22 always presents a surface element 22a, substantially at right angles to the axis of the radiation emitted, at the moment when it is nearest the emitter 24 and receiver 25.

Of course, the signal form receiver 25 may be amplified and peak-clipped, or differentiated, so as to obtain a verticallocating signal with step leading edge and determining said vertical with precision.

WHAT WE CLAIM IS: 1. A gyroscope assembly for mounting on a craft which travels through the air and rotates about the axis along which it travels said gyroscope assembly being for giving a reference of the vertical to said craft, notwithstanding slight variations in trim and yaw of the craft and comprising:: - a sphere for mounting fast with said craft so that one of the diameters of said sphere is parallel to or coincident with the rotation axis of the craft; - an at least substantially toroidal gyroscope rotor disposed concentrically with respect to said sphere and being able to roll on the sphere, said rotor being arranged so that when the sphere is mounted on the craft, the plane of the rotor is inclined by an angle determined with respect to said rotation axis of said craft; - said rotor having a surface of revolution which is reflecting for a determined radiation, e.g. infrared radiation; - an emitter and a receiver of said radiation for fixing on a portion of said craft so that they are, before the launching of said craft, in a determined relationship with respect to the vertical;; - said emitter and receiver and said surface of revolution being for arrangement so that, after launching of said craft when this latter rotates about said axis, said receiver receives, during a small portion of each revolution of said craft, the radiation emitted by said emitter and reflected by said surface of revolution, when said emitter and said receiver occupy, during said portion, a position corresponding to said predetermined relationship with respect to the vertical.

2. A gyroscope assembly as claimed in Claim 1, wherein said angle is close to 45 .

3. A gyroscope assembly as claim in Claim 1 or 2, in which the rotor is formed by two side members and a peripheral annular body assembled with one another, wherein said reflecting surface of revolution is made on the peripheral annular body of the rotor of the gyroscope.

4. A gyroscope assembly as claimed in Claim 3, wherein each side member has a cylindrical projection, and one of the projections interfits in the other.

5. A gyroscope assembly as claimed in Claim 3 or 4, wherein, between the side members and the annular body, there is arranged a toroidal chamber which contains at least one propellant charge and at least one igniting device, the or each igniting device having a firing conducting wire passing through said annular body through a port forming a nozzle for ejecting the gases produced by the explosive charges and maintaining said rotor in its inclined position before firing.

6. A gyroscope assembly as claimed in Claim 5, wherein there are at least two diametrically opposite igniting devices, the conductors for firing these igniting devices passing through the annular body through pairs of gas ejection ports, diametrically opposite in twos.

7. A gyroscope assembly as claimed in any preceding claim, wherein the emitter and the receiver are for mounting near each other, so that their axes of emission and reception are substantially parallel to the axis or rotation of the craft.

8. A gyroscope assembly as claimed in any preceding claim, wherein the reflecting surface is a convex surface of revolution of which the centre of the axis of curvature thereof lies on the centre of the sphere.

9. A gyroscope assembly as claimed in any preceding claim, wherein said sphere is adapted to be made fast with the craft by means of diametrically opposite pointed rods, cooperating with corresponding recesses in said sphere, lying on an axis parallel or coincident with the rotation axis of the craft.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. angular radial position of said missile is determined with respect to the vertical and corresponds to the initial position (shown by Figure 1.). This signal enables the position of the movable surfaces to be coordinated with respect to the piloting controls. When the missile undergoes a slight variation in yaw or in trim, the position of the rotor varies slightly, but the section of the reflecting part 22 makes it possible to continue to obtain upon each revolution of the casing 2, a connection by reflection between the emitter 24 and the receiver 25. In fact, due to its form, said part 22 always presents a surface element 22a, substantially at right angles to the axis of the radiation emitted, at the moment when it is nearest the emitter 24 and receiver 25. Of course, the signal form receiver 25 may be amplified and peak-clipped, or differentiated, so as to obtain a verticallocating signal with step leading edge and determining said vertical with precision. WHAT WE CLAIM IS:

1. A gyroscope assembly for mounting on a craft which travels through the air and rotates about the axis along which it travels said gyroscope assembly being for giving a reference of the vertical to said craft, notwithstanding slight variations in trim and yaw of the craft and comprising:: - a sphere for mounting fast with said craft so that one of the diameters of said sphere is parallel to or coincident with the rotation axis of the craft; - an at least substantially toroidal gyroscope rotor disposed concentrically with respect to said sphere and being able to roll on the sphere, said rotor being arranged so that when the sphere is mounted on the craft, the plane of the rotor is inclined by an angle determined with respect to said rotation axis of said craft; - said rotor having a surface of revolution which is reflecting for a determined radiation, e.g. infrared radiation; - an emitter and a receiver of said radiation for fixing on a portion of said craft so that they are, before the launching of said craft, in a determined relationship with respect to the vertical;; - said emitter and receiver and said surface of revolution being for arrangement so that, after launching of said craft when this latter rotates about said axis, said receiver receives, during a small portion of each revolution of said craft, the radiation emitted by said emitter and reflected by said surface of revolution, when said emitter and said receiver occupy, during said portion, a position corresponding to said predetermined relationship with respect to the vertical.

10. A gyroscope assembly substantially

as described hereinabove and illustrated in the accompanying drawings.

11. A craft which travels through the air and rotates about the axis along which it travels, provided with a gyroscope assembly according to any one of the preceding claims.