CH346084A - Pivoting device for the moving assembly of a precision device - Google Patents

Description

The subject of the present invention is a device for pivoting the mobile equipment of a precision device, in particular a measuring or control device, which is characterized in that it comprises two extremities of axes shaped in the shape of a point and each cooperating with a stone forming a flange, one of these stones being arranged to slide in a tube and being subjected to the action of a spring constantly applying it against the end of the corresponding pin, in order to avoid any longitudinal play between stones and pivots.

The drawing shows, by way of example, two embodiments of the device according to the invention. fig. 1 is an axial sectional view of the First embodiment; fig. 2 is a similar view, relating to the second embodiment. In the example shown in FIG. 1, this is a compass comprising a case 1 inside which a disc 2 can rotate, integral with an axis 3. As is known, the disc 2 carries magnetic pieces 4. which one can observe the graduation that bears the 1st disc 2.

The two extremities 6, 7 of the axis 3 are both fashioned in the shape of a point ending in a portion of a sphere of very small radius. The end 6 presses against the fand of a hollow of a toadstone 8 (ruby) fixed in a housing 9 of the fand of the case 1, the radius of curvature of the fand of the hollow being a little greater than that of the end of the the Point 6. As for the Point 7, it cooperates with a similar hollow of a toad stone 10 able to slide axially inside a tube 11 Passing with hard friction through a central path of the glass 5 to which it is fixed by gluing for example. A helical compression spring 12 is arranged between the fand 13 of the tube 11 and the mobile stone 10, so as to constantly apply, with a certain pressure, this stone against the end 7 of the axis 3.

The second form of execution (fig. 2) differs from the first in certain elements only. To simplify the explanation, the Parts of this second form of execution which are identical to Parts of the First, are designated by the same reference number as in FIG. 1, but accompanied by the subscript a.

The fand 14 of the case presents a central boss 15, in which is practiced a blind hole 16 in which a tube 17 is driven. - dine for the lower end 6a of Faxe 3a. A compression spring 20, arranged between the stone 18 and the end of the shaft 16, constantly urges this stone to remain in contact, through the end of its recess 19, with the lower end 6a of the pivot 3a.

The upper pivot 7a cooperates with a center plate 10a, the assembly of which is completely identical to that indicated in FIG. 1.

In the embodiment according to FIG. 2, there are two crowns 21, 22, made of rubber or other elastic material, each fixed at the location of the open end of one of the tubes 11a, 17. These crowns are cylindrical in shape on the outside, conical on the outside. inside, and are embedded at their base,

in cavities made at the end of 11a and 15. The circular edge 23, respectively 24, resulting from the cylindrical-cone intersection, emerges from the corresponding cavity and flexibly receives the shocks of the moving equipment (pivot , dial, magnet) which result from axial movements insufficiently damped by the springs. Indeed, at the start of an impact against one of the edges 23, 24, the elasticity is great, thanks to this edge shape, but an increase in the compression creates a rapidly increasing resistance.

This arrangement offers, with respect to that according to FIG. 1, The additional advantage of a so-called shock mounting.

In the two cases that Fon has just described, fax 3, 3a cannot oscillate laterally, so that disc 2 remains constantly parallel to glass 5, 5a and can consequently be very close to this glass; which avoids parallax errors in. reading, an obviously important advantage.

Of course, a screw intended to adjust the tension of the spring or springs (12, 12a, 20) can be added to the devices described.

In a variant, one could provide the two stones carried by the disc 2, at least one of them being spring-loaded. In this case, one of the tips such as 6 would be fixed to the bottom of the case, while the other would be fixed relative to the glass 5.

Instead of using stones with a hollow, one could also use the bearings employed in watchmaking and comprising two stones, one pierced, forming a bearing for the axis which crosses it, and the other plate forming a plate. In this case, the slight lateral clearance between the face and the wall of the drilled stone hole corresponded to a possible inclination of the axis which is quite negligible in practice.

The devices described have the following advantages: a) absence of disturbances resulting from temperature variations; b) automatic recovery of pivot wear; c) preservation of the pivot, because the contact between the pivot and the jewels is here maintained at all times, which avoids, after the shock, on returning to the normal position, the pernicious collision of the steel point against the jewel; d) lowering of the cost price, since it is not necessary to work with high precision to obtain a perfect adjustment of the stones and the pivot.

Compared to devices comprising a single pivot, on which the mobile equipment rests - as is the case in the usual compasses - the devices described have the following advantages: e) blocking of the mobile equipment during transport is superfluous; f) possibility of having a minimal and strictly constant distance between the dial and the overlying graduated glass, hence always correct readings.

In addition, in the case which provides for rubber stops, the preservation of the points is perfectly ensured. As already noted, the invention is not limited to the case of compasses. It could apply, for example, to the mounting of the balance wheel of certain timepieces, to electrical measuring devices such as voltmeters and ammeters, to rev counters or the like, to on-board devices intended to be mounted on aircraft, to various control devices, used in particular in ballistic missiles or in rockets, to small electric motors of the Ferrari type for example, to photoelectric devices, or even synchronous electric devices commonly called syncs.

Experience has shown that the d & rit device gives complete satisfaction, particularly in watchmaking. If the pressure exerted by the spring 12 (respectively by the springs 12a and 20) is suitably chosen, a correct operation is obtained, ensuring the durable adjustment of the pivot between the bearings. This avoids the inconvenience of assemblies on a single point, which not only constitute an inconvenience and a waste of time for their transport and for reading, but also a risk of deterioration due to collisions and hammering. - p6t6 of the point against the stone.

In the assemblies described, which practically eliminate all longitudinal play between pivot and ruby, there is less friction and consequently braking than in the various assemblies using ball bearings. For certain devices which must be both sensitive and transportable (the compass being just one example), the arrangement described may therefore be more suitable than ball bearings.

Claims (1)

CLAIM Device for pivoting the moving assembly of a precision device, characterized in that it comprises two shaft ends shaped in the shape of a point and each cooperating with a stone forming a plate, one at least of these stones being arranged to slide in a tube and being subjected to the action of a spring applying it constantly against the end of the corresponding axis, in order to avoid any longitudinal play between stones and pivot.