FR2479486A1 - Spherical telescope or radar bowl mounting - has sphere supported on two rings by ball bearings or pads to permit pivoting in all directions - Google Patents

Abstract

The spherical telescope (1) mounting has a sphere (4) supported on a support block (13) and can pivot in all directions about its centre. The support has a number of independent pads supporting the sphere. Each has a shoe pressing on the sphere via ball bearings (11) or by fluid bearings. These are concentric with the sphere. The pads can be moved by a type of jack. The annular support block is placed below the sphere with its vertical axis passing through the sphere centre. There can be two movable rings (9,10) joined to the first and second pad groups.

Description

 The present invention relates to spherical mounts comprising a support device pivoting around the center of the sphere, usable in particular as telescope mounts.

 The technical sector of the invention is that of the construction of pivoting mounts of orientable devices such as telescopes, radars and solar collectors.

Known telescopes include a concave mirror which reflects the light rays towards means for observing, recording or analyzing images. This mirror is carried by an adjustable frame to follow the movement of the stars.

Telescopes are known, the swivel mount of which consists of a sphere. Such a spherical mount has the advantage of being orientable in all directions by rotations around the center of the sphere which remains fixed. It is thus possible to place in the center a mirror for returning the light beam to an observation laboratory. Networks of telescopes are known in particular which are arranged around an observation laboratory in which the images of the same celestial body, captured by the various telescopes, are recombined. This technique is known as aperture synthesis or interferometry. It increases the angular resolution which we know is inversely proportional to the opening diameter.

 Spherical telescope mounts are particularly suitable for the construction of such telescope arrays.

Spherical mounts also have advantages when used as individual telescope mounts.

Indeed, it is known to build hollow spherical reinforced concrete shells having a thickness of the order of 50 mm, inside which one can accommodate a cylindrical concrete tube supporting a parabolic mirror with a large opening diameter.

The spherical geometry means that the inertia of the frame, and consequently its deformations, are appreciably constant for the various positions of the sphere and this advantage is very important due to the very high geometric precision to which these devices must respond.

A spherical mount resting on a suitable base which makes it possible to pivot the sphere around its center, makes it possible to aim practically n? matter what point of the sky.

 However, the realization of a device making it possible to support a concrete sphere and to drive it in rotation around its center, according to a determined movement, poses difficult problems.

 Hollow concrete spheres, used as telescope mounts, are very bulky and very heavy volumes. The diameter of these spheres is for example of the order of 4 to 8 m and the weight of the order of several hundred tonnes. In addition, these spheres generally have a meridian opening intended for the passage of the beam of reflected light.

 To support the sphere in a rotary way, one could think of placing it on a concave spherical cap of the same radius and of inserting a film of liquid between the external surface of the sphere and the cap. This solution cannot be suitable, because the concrete surface of the sphere is not waterproof and the meridian opening prohibits this solution.

One could also think of placing the sphere on trains of cylindrical balls or rollers, but in this case, the contacts between the sphere and the balls or the rollers are punctual and the stresses which one arrives exceed the compressive strength of the concrete .

The objective of the present invention is to provide new devices which make it possible to support a concrete sphere used as a telescope mount and to drive the latter in rotation around its center in all directions, by controlling the rotations to the movement of 'a star.

This objective is achieved by means of a device which comprises a plurality of supports which support said sphere and each of these supports comprises a shoe which bears against the external face of said sphere, two spherical surfaces which are concentric with said sphere and between which are placed balls or fluid bearings allowing a relative displacement of the two bearings, a disengageable cylinder which makes it possible to maintain alternately a first and a second group of pads pressed against the sphere and means for moving said pads step by step .

A device according to the invention comprises a fixed annular support in the form of a torus, which is arranged below the sphere, the vertical axis of which passes through the center of the sphere and on which said supports rest. It further comprises two movable rings which are connected respectively to the first and to the second group of pads. Each movable ring comprises at least three jacks which connect it to the fixed annular support and which make it possible to rotate the ring in all directions around the center of the sphere. Preferably, each movable ring comprises two pairs of diametrically opposite jacks and the two jacks of each pair have rods which converge towards a same point on the movable ring around which they are articulated.

Each actuator actuating the movable rings is equipped with a linear displacement sensor and is supplied with compressed fluid through a solenoid valve and the various solenoid valves are controlled automatically so that the linear displacements of the actuators follow programmed values which correspond to the trajectory of a given star.

 The invention results in new orientable support devices for a spherical telescope mount or an orientable device.

 The devices according to the invention have the advantage of being able to support loads of several hundred tonnes which correspond to the weight of concrete spheres, without the stresses in the points of support of the sphere on the pads, exceeding the resistance compression of concrete. You just have to choose the number of pads and the support surface of each one properly.

 Another advantage of the devices according to the invention is that they make it possible to obtain rotations of the sphere, around its center, of very large angular opening and they therefore make it possible to follow a star with a telescope throughout its visible trajectory.

 Another advantage of the devices according to the invention is that they make it possible to control the movements of the sphere which are obtained by jacks whose linear displacement can be easily measured, which makes it possible to control the movement of the sphere to follow a programmed movement corresponding to the trajectory of a determined star.

 The following description refers to the appended drawings which represent, without any limiting nature, exemplary embodiments of devices according to the invention.

 Figure 1 shows an axial section of a spherical mount telescope according to the invention.

 Figure 2 is an elevational view of an embodiment of a device according to the invention for supporting a spherical telescope mount.

 Figures 3, 4 and 5 are partial views of devices according to Figure 2.

 Figures 6 and 7 are vertical sections through two planes perpendicular to each other of an alternative embodiment of a dispos tif according to the invention.

 FIG. 1 represents a telescope 1 comprising a parabolic mirror 2 with a large aperture and an axis z zi. The mirror 2 is mounted in the bottom of a coaxial cylindrical tube 3 which is carried by a spherical mount 4 whose center 0 is located on the axis z zi. The tube 3 carries a first deflection mirror 5 placed at the focal point of the parabolic mirror and a second deflection mirror, inclined at 45 on the axis z zl, and placed at the center 0. The drawing of a incident light ray I parallel to the axis z zl, which is successively reflected by the mirrors 2, 5 and 6. The cylindrical tube 3 and the sphere 4 each have a narrow opening 7 and 8 through which the rays reflected by the mirror 6 pass to go towards a laboratory in which one can superimpose the images provided by several identical telescopes to observe, record or analyze them.

One of the problems to be solved is to support the sphere 4, so that it is free to rotate in any direction around the center 0, to maintain the axis z zl pointed towards a star. The mirror 2 has an opening diameter of, for example, between 1 m and 4 m and the sphere 4 has a diameter of the order of 4 to 8 m.

 The sphere 4 and the tube 3 are constructed for example of reinforced concrete. They include a concrete reinforcement, covered with several layers of wire mesh, onto which concrete is sprayed forming a shell having a splinter of the order of 50 mm. The total weight is of the order of a few tens to several hundred tonnes.

 At the end of cementing, the fresh cement is scraped from the external surface with a gauge cut out in the shape of an arc of a circle and mounted on a pivot.

Then the external surface is machined very precisely by a lapping technique using an abrasive polisher having the shape of a spherical cap.

 The sphere 4 is placed on two circular rings 9 and 10 situated around the parallel 450 and below the center 0. The rings 9 and 10 have a spherical convex external face of center 0, parallel to the surface of the sphere 4. The external surfaces rest on balls 11 which can be replaced by hydrostatic pads. The balls 11 roll on the concave and spherical surface 12 of an annular support 13 placed on the ground. The height of the support 13 is such that the lowest point of the sphere is above the ground.

 The balls 11 can roll on the surface 12 in all directions so that by using three hydraulic, pneumatic or electric jacks acting in planes tangent to the sphere 4 in non-parallel directions and by varying the relative displacements of these jacks , it is possible to rotate the sphere around any axis passing through the center 0.

 The problem that arises is that of limiting the angular movement of the sphere. Indeed, when the sphere rotates, the balls 11 roll on the spherical surface 12 and when they arrive at the limit thereof, it is not possible to go any further.

 The device according to 1 invention makes it possible to solve this difficulty by means of two independent movable rings 9 and 10 which alternately support the sphere 4 thanks to a clutch device which makes it possible to separate the sphere alternately from one or the other of the two rings. Thus, the angular movement of the sphere 4 becomes unlimited because the rotational movement started on a first ring continues on the second while the first returns to its initial position. One finally obtains an unlimited movement step by step according to a principle analogous to that which is used for walking by taking support alternately on one leg then on the other. Obviously, the alternating movement of the two rings 9 and 10 includes a phase in which the two rings both support the sphere.

In order to provide a practical device for alternately supporting the sphere 4 on independent mobile supports, the sphere is placed on a plurality of supports, for example on 24 radial supports distributed all around a small circle of the sphere.

FIG. 2 represents a view in elevation on a larger scale of the device used. The reference 14 represents a fixed support in the form of a torus whose vertical axis z z1 passes through the center of the sphere. This support 14 fulfills the same function as the support 13 of FIG. 1. The support 14 carries a plurality of concave spherical bearing surfaces 15 concentric with the sphere 4 which have the same function as the bearing surfaces 12 of FIG. 1 and on each of which rolls a ball 16.

Short stroke cylinders 17 maintain, on the one hand, a shoe 18 pressed against the sphere 4 and they maintain, on the other hand, a convex spherical bearing 19, coaxial with the sphere 4, pressed against the ball 16.

 There is shown in Figure 2 only two cylinders 17a and 17b so as not to obscure the drawing. The jack 17a is fixed by gussets 20a to a movable ring 21. The jack 17b is fixed by gussets 20b to a movable ring 22.

 The jacks 17 form two assemblies, the elements of which are fixed alternately to the ring 21 and to the ring 22 and a hydraulic control device alternately presses the jacks of the group 17a and the jacks of the group 17b. The weight of the sphere is supported by the pads 18 and the surface thereof is calculated so that the stresses exerted on the sphere at the points of contact of the pads are less than the compressive strength of the concrete of the sphere . The weight of the sphere is transmitted by the group of jacks which are pressurized to the fixed support 14. The balls 16, which roll on the spherical bearings 15 and 19, force the sphere to pivot around its center.

 All the rotational movements of the sphere around its center can be obtained with a minimum of three jacks acting on each movable ring 21 or 22, to move it around the center 0, in any direction. A first movable ring is moved, at the same time as the jacks 17, which are fixed to this ring, apply the pads 18 against the sphere, so that the movement of the ring which is moved is transmitted to the sphere by a group of pads 18, while the other ring, and the other group of pads 18 remain stationary and separated from the sphere.

 After having thus displaced the sphere 4 by a sufficiently small angle so that the balls 16 of the jacks 17, which carry the sphere, do not risk escaping the spherical bearings 15 and 19, the sphere is supported on the other group of pads 18 which are connected to the second movable ring and the second movable ring is moved while the first movable ring is brought back to its initial position and so on, the movements of the two movable rings 21 and 22 are alternated, each of these returning to take its initial position while the second drives the sphere.

 A preferred way of placing the jacks is shown in part in FIG. 2.

 Each movable ring 21 and 22 is moved by two pairs of jacks which push on two points of each ring which are for example two diametrically opposite points.

 There is shown in Figure 2 two cylinders 23 and 24 which are fixed on a bracket 34 carried by the ring 14 and which respectively push the movable ring 21 and the movable ring 22. These two jacks are located substantially in a plane tangent to sphere 4.

FIG. 4 shows a pair of jacks 23 and 28 whose rods converge towards a point 27 of the movable ring 21 around which they are articulated as well as a pair of jacks 24 and 29 whose rods converge on a point 30 of the movable ring 22 around which they are articulated.

 By composing the relative displacements of the two cylinders of each pair 23, 28 or 24, 29, it is possible to vary the direction of movement of the junction point 27 or 30. By acting on the two pairs of diametrically opposite cylinders of each ring mobile, we can rotate each of the mobile rings in any direction around the center O of the sphere by driving the sphere in this rotation through the pads 18 connected to the mobile ring. One of the four cylinders that push each ring can be a passive cylinder or a spring applying a constant restoring force to the mobile ring, and the other three cylinders are single acting. Each cylinder has a linear displacement sensor which is connected to a control computer.

 The numerical values of the linear displacements of the various cylinders are programmed so that the axis of the telescope remains pointed towards the same star, whose movement is well known.

The fluid supply of each actuator comprises a solenoid valve which is remotely controlled by the computer which compares the displacement values measured by the sensors with the programmed values and which acts automatically on the solenoid valves to make these values coincide.

 Thus, by combining the movements of the thrust cylinders of the movable rings and the clutching and disengaging cycles of the jacks 17, it is possible to obtain any programmed movement of the sphere 4 around its center.

 The orientation of the sphere can be measured at any time by means of angular displacement sensors mounted on controlled bubble levels or on inertial platforms or by means of interferometric devices allowing counting of fringes in coherent light.

FIG. 3 represents, on a larger scale, a partial median section of the sphere 4 and of an embodiment of one of the supports of the sphere on the fixed annular support 14. This figure shows one of the cylinder cylinders 25, fixed to the fixed ring 14 and the piston 26 of the clutch cylinder 17 which is a very short stroke piston.

 The piston 26 supports a rolling surface. There is a ball 16 which rolls between the concave spherical surface 15 and the convex spherical surface 19. The extension of the spherical surfaces 15 and 19 is shown in dotted lines. These two spans are made of hard steel and machined according to spherical surfaces concentric with sphere 4.

 FIG. 3 shows one of the pads 18 which is kept pressed against the external surface of the sphere by the thrust of the jack 17.

 The face of the pad 18, which is in contact with the surface of the sphere, is machined along a spherical surface of the same radius as the sphere.

It is preferably lined with a layer of plastic, for example polytetrafluoroethylene. The shoe 18 shown in FIG. 1 is connected to the movable ring 21 by a gusset 20.

The device comprises 24 pads 18, 12 of which are connected to the ring 21 and 12 to the ring 22.

 Figure 4 is a partial view from the center of the sphere of the support and orientation device of the sphere, the sphere being removed. This figure shows the fixed ring 14 and the two movable rings 21 and 22. We see six of the 24 pads 18 which are divided into two groups, a group of pads 18a, connected to the ring 21 by gussets 20a and a group of pads 18b connected to the ring 22 by gussets 20b. This figure shows the two cylinders 23 and 28 whose rods are articulated around the same point 27 fixed to the movable ring 21 and the two cylinders 24 and 29 whose rods are articulated around the same point 30 which is fixed to the movable ring 22.

Figure 5 shows a section on a larger scale passing through the axis of one of the support cylinders 17. We find in this view the sphere 4 placed on a pad 18, which is connected by gussets 10 and by a cylindrical ring 32 to the movable ring 21. We also see the concentric spherical surfaces 15 and 19 on which the ball rolls 16. We finally see the disengageable cylinder 17 composed of a cylinder 25 which is welded to the fixed support 1 and piston with short stroke 26. This drawing 11 shows the arrival of pressurized oil 31 which feeds the jack and which allows the clutch which alternately disengages and engages the jacks which control the group of pads 18a and those which control the group pads 18b. The servo solenoid valves are arranged on the oil pipes which lead to the oil inlets 31.

 FIG. 5 also shows a cage 33 which prevents the balls 16 from falling outside the spherical bearings 15 and 19. It will be recalled that the balls 16 can be replaced by fluid bearings.

 Figures 6 and 7 show sections through two axial planes VI-VI and VII-VII perpendicular to each other of an alternative embodiment of a device according to the invention. These figures show the sphere 4 without the telescope and three axes x xl, y y1 and z zl passing through the center 0 of the sphere. Preferably, these axes are orthogonal although this arrangement is not necessary.

 The support device comprises a pivot 35 which makes it possible to rotate the sphere around the vertical axis z z1. The pivot 35 carries two oti several trains of rollers, rollers, balls or ball bearings 36 and 37, parallel to the axis y y1.

On the upper generators of the rollers or rollers or on the tops of the balls, is supported a cylindrical track 38 of radius
R2 and axis y y1. This cylindrical track is the lower surface of an intermediate support 39 which also carries at least two trains 40 and 41 of rollers, rollers, balls or the like, whose axes are parallel to the axis x xl.

On the upper generators of the rollers 40 and 41 or on the tops of the balls, a cylindrical track 42 of radius R1 and axis x x2 is supported. The track 42 is the underside of a support 43 whose concave and spherical upper face follows the shape of the sphere 4 that it supports.

By combining the rotational movements around the three axes x xl, y y1 and z z1, we can rotate the sphere 4 in any direction around the center 0.

 It is possible to fragment each track or each train of rolls into three sections A central section for example the sections 37a, 41a and 43a and into two lateral sections for example the two sections 37b, 41b and 43b and engage alternately on the sphere, ie the section central, that is to say the lateral sections while the other section returns to the initial position, which thus makes it possible to obtain an alternating movement step by step, similar to that of walking on two legs and therefore a possibility of unlimited angular movement despite a limited length of the cylindrical tracks. The vertical pivot can remain permanently engaged. The roller, roller or ball trains can be replaced by fluid bearings comprising a fluid arranged between two parallel cylindrical tracks, which fluid bearings constitute a technical equivalent of a ball or roller bearing.

The foregoing description relates to a telescope, but it is clearly stated that the same spherical mount could be used to support any orientable device, such as for example a radar or a solar collector.

Of course, without departing from the scope of the invention, the various constituent elements of the support devices which have just been described by way of example may be replaced by equivalent elements fulfilling the same functions.

Claims (8)

R E Y E N D I C A T I O N S 1 - Spherical mount, in particular of telescope, comprising a sphere which is  placed on a support device and swivels in all directions  around its center, characterized in that said device  support comprises a plurality of independent supports which support the said sphere and each of these supports has a pad which leans against  the outer face of said sphere, two spherical bearings which are con centric with said sphere and between which balls are placed or fluid bearings allowing relative movement of the two spans, a disengageable cylinder which allows alternately to maintain a first and a second group of skates leaning against the sphere and means  to move said pads step by step. 2 - Frame according to claim 1, characterized in that it comprises a fixed annular support in the form of a torus arranged below said  sphere, the vertical axis of which passes through the center of the sphere and. on ^ the-  what are the said supports. 3 - Frame according to claim 2, characterized in that it comprises  two movable rings which are connected respectively to the first and to the  second group of skates. 4 - Frame according to claim 3, characterized in that it comprises  at least three jacks connecting said fixed annular support to each of two movable rings. 5 - Frame according to claim 4, characterized in that it comprises  two pairs of diametrically opposite cylinders, connecting said support  annular fixed to each of the movable rings. 6 - Frame according to claim 5, characterized in that the two  cylinders in each pair have rods that converge at the same point of said movable ring around which they are articulated. 7 - Frame according to any one of claims 4 to 6, characterized  in that each actuator actuating the movable rings is equipped with a  linear displacement sensor and is supplied with compressed fluid at  through a solenoid valve and the different solenoid valves are controlled  automatically, so that the movements of the cylinders follow  programmed values which correspond to the trajectory of a determined star. 8 - Frame according to claim 1, characterized in that said sphere  is placed on a support which has a vertical pivot, two cy tracks  lindrics whose axes are orthogonal and pass through the center of the  sphere and trains of rollers, rollers, balls rolling on  said cylindrical tracks, which trains are divided into a section  central and in two lateral sections and the device comprises means for alternately engaging on said sphere either the central section or the lateral sections and for moving these step by step.