WO2005021379A1

WO2005021379A1 - Inertia wheel for space vehicle

Info

Publication number: WO2005021379A1
Application number: PCT/FR2004/001821
Authority: WO
Inventors: Philippe Faucheux; Pascal Michel Noël GUAY
Original assignee: Eads Astrium Sas
Priority date: 2003-07-28
Filing date: 2004-07-09
Publication date: 2005-03-10
Also published as: FR2858294A1

Abstract

The invention concerns an inertia wheel comprising at least one inertia mass (1) rotatably mounted through a bearing (2) to at least one ball-bearing whereof the stationary part is designed to be fixed on the space vehicle. The inertia mass (1) incorporates at least one rotating ring (5) of the bearing (2), and said rotating ring (5) is tightly secured to the inertia mass (1). The invention is useful for making inertia wheels, reaction wheels and satellite gyrodynes.

Description

SPARE VEHICLE INERTIA WHEEL

The present invention relates to a wheel intended to be driven in a rotational movement about its axis, and to be used as a flywheel, or as a reaction wheel, for equipping space vehicles. For this reason, in the present specification as in the claims which follow it, the term “flywheel” covers both the flywheels used to create an on-board angular momentum, or the flywheels mounted on gimbal to make gyroscopic actuators (or gyrodynes or CMG), or the reaction wheels intended to create torque by varying their rotational speed, or any other use intended for the equipment of attitude control systems and satellite orientation. Examples of reaction wheels and gyrodynes are given in patents US-3, 968,352, US-6, 135,392 and US-6,305,647, which will be referred to for more details on their subject. We know that a flywheel, standard or custom made, of a space vehicle generally consists of at least one rolling bearing on which is attached at least one mass called “inertia”, making it possible to create the desired inertia, the rotation of which at high constant speed will create an on-board kinetic moment, or the acceleration of which will create the desired reaction torque. By way of example, inertia wheels with an inertia mass added to one or two bearing bearings are shown in FIGS. 1, 4 and 3 respectively of the three aforementioned US patents. This added mass is generally screwed onto an interface piece intended to secure it to the rolling bearing or bearings. It must be extremely precisely centered with respect to the rolling bearing (s) so as to limit dynamic disturbances (during the rotations of the inertia mass around the axis of the bearing (s)), and by consequently the microvibrations, which are generated by the rotation of the mass of inertia, and which are transmitted to equipment on board the satellites, the performance of which can therefore be significantly reduced. For the same reasons, this mass of inertia must be balanced after transfer to the rolling bearing. A major drawback of the known embodiments of flywheels for space vehicles lies in the fact that the centering and balancing faults of the rotating member consisting of the rolling bearing (s) on which it is reported. the mass of inertia will necessarily be amplified typically by a factor of ten compared to the initial settings, when the wheel is subjected, during ground tests or during launching into very unfavorable mechanical vibration environments. This amplification results from uncontrollable displacements between the different parts which constitute the rotating member, that is to say the mass of inertia on the one hand, and the interface part to which it is screwed on the other hand . The aim of the present invention is to reduce the problems and drawbacks linked to the lack of centering and balancing of the inertia masses and to their uncontrollable increase observed after ground vibration tests or after launch, in order to limit its impact in terms of micro-vibrations, and improve its stability. To this end, the invention provides a flywheel for a space vehicle, the wheel comprising at least one flywheel rotatably mounted by a bearing with at least one bearing, the fixed part of which is intended to be fixed to the spacecraft, and which is characterized in that said at least one mass of inertia of the wheel integrates at least one rotating ring of said one bearing, said rotating ring being made integral without play of said mass of inertia. By these terms, it should be understood that said rotating ring and said mass of inertia consist of a single piece or of several pieces hooped together or assembled without play by any technique allowing any relative play between the pieces to be eliminated. The proposed embodiment therefore consists in using part of the bearing structure or at least one of the bearings of the bearing, namely at least one rotating bearing ring, as an integrated part in one piece or hooped together or assembled without play with the mass of inertia. Such an embodiment has the following advantages: the mass of inertia being in one piece or hooped together or assembled without play with at least one rotating ring of at least one bearing, unbalances can thus be minimized by manufacture; in particular, the centering faults, due to the assembly by screwing of the inertia mass on the corresponding bearing or bearings, are eliminated; - the assemblies of the inertia mass (s) on the bearing (s) being eliminated, the phenomena of shake due to vibrations at the interfaces between inertia mass (s) and bearing (s) are eliminated, which guarantees a stability of the imbalance, and therefore stability of micro-vibrations, despite the strong vibrations undergone by the wheel during mechanical tests or when the spacecraft is launched. For these reasons, and advantageously from the point of view of inertia, due to the larger radius of an outer ring relative to an inner bearing ring, the flywheel according to the invention is such that said mass d inertia is in one piece or shrunk together or assembled without play with at least one outer ring of the rolling bearing, another configuration, generally less favorable, being that the mass of inertia is in one piece or shrunk together or assembled without play with at least one internal ring of the rolling bearing. Preferably, the mass of inertia is in one piece or hooped together or assembled without play with a single external ring, or possibly internal, of a bearing comprising two bearings, therefore two rows of rolling elements, with balls or with tapered rollers, mounted face-to-face or, preferably, back-to-back. When this bearing is a rolling bearing comprising a single row of rolling elements, the latter have four points of contact with the inner and outer rings of the bearing. Advantageously, moreover, in order to obtain high inertia, in a limited space, and without thoughtlessly increasing the mass concerned, said mass of inertia comprises: - a full veil or with shelving in sticks, preferably of conical shape or of any other shape radial, relative to the axis of the bearing and which is in one piece or hooped together or assembled without play with said rotating ring of at least one of the bearings of the bearing, and - an external peripheral rim, of a single piece or hooped together or assembled without play with said veil. Advantageously, moreover, and in order to optimize the centering, the value of the inertia for a given mass, in a given size, the rim and the outer ring are bodies of revolution around the axis of the outer ring, and are in one piece or hooped together or assembled without play with said veil, at the respectively external and internal radial ends of the latter. To improve the axial guidance, it is advantageous that the rolling bearing is a preloaded bearing by back-to-back mounting of two rows of rolling elements, axially spaced from one another between a single rotating ring and two non-rotating rings which may or may not be separated from each other by at least one axial spacer. In the first case, as an exemplary embodiment, the rolling bearing can be preloaded with two rows of balls, of the oblique contact type or of the deep groove type, between the rotating ring, preferably external and the two fixed rings, preferably internal. The use of flywheels according to the invention makes it possible to significantly reduce imbalances (typically by a factor of 10), and consequently micro-vibrations, which makes it possible to significantly improve the pointing performance of satellites. . The structure of the inertia wheels according to the invention is all the more suitable for wheels rotating at high speeds, for which small imbalances can cause significant micro-dynamic disturbances, since the effect of these disturbances is proportional to the square the speed of rotation of the wheel. Other advantages and characteristics of the invention will emerge from the description, given below without implied limitation, of embodiments described with reference to the appended drawings in which: - Figure 1 represents a schematic view in axial section of 'a first example of a flywheel according to the invention, and - Figure 2 shows, substantially similar to Figure 1, a second example of a flywheel according to the invention. The flywheel shown in FIG. 1 comprises a flywheel mass 1 rotatably mounted on a rolling bearing 2, around the axis XX of this bearing 2. The flywheel mass 1 consists of a rim 3, external device, having a symmetry of revolution about the axis XX, and preferably in one piece with a veil 4, but which can be hooped together, or assembled without play and connected, on the side of its internal face, with the peripheral external radial end of the web 4, in the form of a frustoconical solid disc of axis XX, and itself in one piece or hooped together, or assembled without play by its internal radial end, with the external rotating ring 5 of the rolling bearing 2. The veil 4 can be full, with symmetry of revolution about the axis XX, or perforated, with a shelving in sticks, the radii of which are inclined in axial planes. The web 4 is linked by its external and internal radial ends respectively to the middle, in the axial direction (along the axis XX), of the internal radial face of the rim 3, and to the external radial face of an end part. axial 5a (upper in FIG. 1) of the rotating external ring 5. The veil 4 can also be planar and radial, solid or perforated with radial spokes or have any other shape making it possible to improve its rigidity while minimizing its mass. The inertia mass 1, preferably consisting of a single piece forming the rim 3, the web 4 and the outer ring 5, therefore integrates the latter, the mass of which contributes to providing the inertia necessary for the inertia wheel . The rim 3, the web 4 and the outer ring 5 are therefore advantageously made of a single piece constituting the mass of inertia 1. But as a variant, the latter can be made up of several pieces hooped together without play, or assembled without play any other way. The mass of inertia 1 thus formed, of a metal or metallic alloy, is balanced and centered on the axis XX of the rolling bearing 2, and this mass of inertia 1 can advantageously be of revolution around the axis XX. Like the rim 3, in the external radial position on the mass 1, the external ring 5, in the internal radial position on the mass 1, is also a body of generally cylindrical shape, and, in the example shown, the rim 3 and the outer ring 5 have substantially the same axial dimension

(parallel to the X-X axis) to minimize the size of the wheel. In the example shown in Figure 1, the bearing 2 is composed of two preloaded bearings and advantageously mounted back-to-back, comprising two rows of balls 7a and 7b, which are offset from one another according to the axis XX, and each located between an axial end portion 5a or 5b of the common rotating external ring 5, radially outward, and respectively one of two non-rotating or fixed internal rings 6a and 6b, either directly in contact with each other, or spaced axially from each other by a tubular spacer 8, radially inward., and intended to be fixed to the structure of the satellite. In this assembly, the rings 5, 6a and 6b are coaxial around the axis X-X of the rolling bearing

2, and although FIG. 1 represents a bearing with two deep groove ball bearings 7a and 7b, the rolling bearing 2 can have two angular contact ball bearings, as shown schematically by the axes in solid lines crossing the balls 7a and 7b between their points of contact with the two corresponding rings, with an orientation which, in FIG. 1, indicates a preload of the bearings mounted back-to-back. The use of a single rotating external ring 5 and two fixed internal rings 6a and 6b provides better stability and allows easier assembly. To facilitate the positioning of the rolling bearing 2, the two internal rings 6a and 6b of which must be supported on the platform of the satellite or on a box of equipment on board the satellite, it may be advantageous that, as shown in the figure 1, the axial dimension of the two internal rings 6a and 6b as well as of the tubular spacer 8 which separates them is substantially equal to the axial dimension of the single external ring 5. The example of a flywheel in FIG. 2 also comprises a mass of inertia 9, comprising, substantially like the mass of inertia 1 of FIG. 1, an external peripheral rim 11, similar to the rim 3, and in one piece with a frustoconical web 12, similar to the wall 4 of FIG. 1, and itself in one piece with an axial end part of a rotating ring of a bearing 10 with two ball bearings mounted preloaded, preferably back-to-back, as level 2 of figure 1. May s, in this second example, the web 12 is in one piece with the internal rotating ring 14, which is common to the two ball bearings, the two rows of balls 15a and 15b are axially offset and located between one respectively of two axial end portions 14a and 14b of the single common rotating inner ring 14 and one respectively of the two fixed outer rings 13a and 13b of the bearings. These fixed external rings 13a and 13b can bear axially against each other, or, as shown in FIG. 2, kept spaced apart by an axial tubular spacer 16, inside a sleeve 13 of tubular support. attached to the supporting structure. As a variant, the mass of inertia 9 can be produced by assembling its three components, the rim 11, the web 12 and the internal rotating ring 14, without play, or of component parts of these components, for example by hooping together and without play of these parts or components. The mass of inertia 9, like the mass of inertia 1 of FIG. 1, is balanced and centered on the axis XX of the bearing 10 with two bearings, and can advantageously be of revolution around this axis XX. Such flywheels therefore have a flywheel mass 1 or 9 which can be centered extremely precisely with respect to the rolling bearing 2 or 10, because the balancing and centering of the flywheel mass 1 or 9 which incorporates the single external ring 5 or internal 4 of the rolling bearing 2 or 10, as well as their good resistance over time after having undergone severe vibratory environments, are facilitated compared to the achievements of the prior art. The manufacture of such a mass of inertia 1 or 9 makes it possible to reduce imbalances and to overcome the problems of connection between the mass of inertia and the rotating ring of the bearing or bearings, of which the mass of inertia is integral in rotation. Such a mass of inertia 1 or 9 is particularly suitable for producing inertia wheels rotating at high speed, such as those used on small satellites which, because of their low mass and inertia, are very sensitive to micro-vibrations. .

Claims

1. Inertia wheel, for a space vehicle, the wheel comprising at least one inertia mass (1, 9) rotatably mounted by a bearing with at least one bearing (2, 10), the fixed part of which is intended to be fixed to said spacecraft, characterized in that said at least one mass of inertia (1, 9) integrates at least one rotating ring (5, 14) of said bearing (2, 10), said rotating ring (5, 14) being made integral without play of said mass of inertia (1, 9).

2. Flywheel according to claim 1, characterized in that said rotating ring (5, 14) and said flywheel (1, 9) consist of a single piece, or of several pieces hooped together, or assembled by any technique to eliminate any relative play between the parts.

3. Flywheel according to claim 2, characterized in that said flywheel mass (1) is in one piece or hooped together or assembled without play with at least one outer ring (5) of said bearing (2) .

4. Flywheel according to claim 3, characterized in that said flywheel mass (1) is in one piece or hooped together or assembled without play with a single outer ring (5) of said bearing (2).

5. Flywheel according to claim 2, characterized in that said flywheel mass (9) is in one piece or hooped together or assembled without play with at least one internal ring (14) of said bearing (10) .

6. Flywheel according to claim 5, characterized in that said flywheel mass (9) is in one piece or hooped together or assembled without play with a single internal ring (14) of said bearing (10).

7. Flywheel according to any one of claims 1 to 6, characterized in that the bearing is a rolling bearing comprising a single row of rolling elements with four points of contact with the inner and outer rings of the bearing .

8. Flywheel according to any one of claims 1 to 6, characterized in that the bearing is a rolling bearing with two rows rolling elements (7a, 7b; 15a, 15b), with balls or tapered rollers, mounted face-to-face or preferably back-to-back.

9. Flywheel according to any one of claims 1 to 8, characterized in that said flywheel mass (1 or 9) comprises: - a web (4, 12) full or with shelving in sticks, preferably of conical shape or any other radial shape, with respect to the axis (XX) of the bearing (2, 10) and which is in one piece or hooped together or assembled without play with said rotating ring of at least one bearings of the bearing (5, 14), - an outer peripheral rim (3, 11), in one piece or hooped together or assembled without play with said web (4, 12).

10. Flywheel according to claim 8, characterized in that the rolling bearing is a preloaded bearing, preferably back-to-back, or face-to-face, with two rows of rolling elements, balls or rollers conical (7a / 7b, 15a / 15b), axially spaced from each other between a single rotating ring (5, 14) and two fixed rings (6a / 6b, 13a / 13b) separated or not one of the other by at least one axial spacer (8, 16).

11. Flywheel according to claim 10, characterized in that said rolling bearing (2, 10) is a bearing with two rows of balls or conical rollers (7a / 7b, 15a / 15b), with oblique contact or with deep grooves, between said rotating external ring (5, 14) and the two fixed internal rings (6a / 6b, 13a / 13b).