US3848711A - Electrical coupling between elements in relative motion in respect of each other - Google Patents

Abstract

The electrical coupling of two components A and B, which execute a relative motion to one another, is achieved by means of one or more curved conductive blades operating below their elastic limit, and guided along surfaces over which they roll without slip, with a substantially constant radius of curvature; the blades are inserted at their ends to the conductive portions of said surfaces.

Description

United States Patent [191 Brenot et al.

ELECTRICAL COUPLING BETWEEN ELEMENTS IN RELATIVE MOTION IN RESPECT OF EACH OTHER Inventors: Claude Brenot; Gaston Mollard, both of Paris, France Assignee: Thomson-CSF, Paris, France Filed: July 12, 1973 Appl. No.: 378,628

Related US. Application Data Continuation of Ser. No. 180,003, Sept. 13, 1971, abandoned.

US. Cl. 191/12 R, 339/5 R Int. Cl H02g 11/00 Field of Search 191/12 R; 339/6 R, 6 A,

References Cited UNITED STATES PATENTS 11/1968 Ober 191/12 R Nov. 19, 1974 3,505,544 4/1970 Helms ..3l0/13 3,599,165 8/1971 Wendell ..339/5 Primary Examiner-Robert S. Ward, Jr. Assistant Examiner-D. W. Keen Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT The electrical coupling of two components A and B, which execute a relative motion to one another, is achieved by means of one or more curved conductive blades operating below their elastic limit, and guided along surfaces over which they roll without slip, with a substantially constant radius of curvature; the blades are inserted at their ends to the conductive portions of said surfaces.

2 Claims, 6 Drawing Figures PATENM; nuv 1 9 I974 SHEET 2 OF 3 P'I XTIiNTEL NOV 1 91974 SHEET 3 OF 3 ELECTRICAL COUPLING BETWEEN ELEMENTS IN RELATIVE MOTION IN RESPECT OF EACH OTHER This is a continuation of application Ser. No. 180,003, filed Sept 13, 1971, now abandoned.

The present invention relates to a device for the transmission of multiple electrical data between two elements between which there is relative movement. In numerous devices, as for example gyroscopes, incidence detectors, electrical data have to be transmitted between components between which there is relative, generally linear or circular motion, this without any risk of wear and poor contacting (phenomena which do occur in the case of sliding contacts). On the other hand, in certain instances and in particular in the context of gyroscopes, the mechanical forces generated by the electrical coupling device have to be kept very small.

The device in accordance with the invention meets all these requirements; moreover, it has the advantage over the known kind of flexible connections employed in telephone systems, that it is more resistant to vibration; finally, it enables the transmission of relatively heavy currents (as much as some few amps, for example), which is practically impossible under the same circumstances, when using wire connections, which can only carry a few milliamps.

.According to the invention, there is provided an assembly for the electrical coupling of two elements in relative motion, in respect of each other, said assembly comprising two components respectively integral with said elements, said components having respective walls with the same centre of curvature, and at least one flat conductive spring, said spring having ends respectively attached to said components, said spring being arranged to roll without slip, with a substantially constant curvature, on said walls in the course of said motion, the mechanical characteristics of'the spring being such that during the movement the elastic limit is not reached.

For a better understanding of the invention and to show how the same may be carried into effect, reference will be made to the drawings accompanying the ensuing description and in which:

' FIGS. 1 and 2 are diagrams illustrating the principle of the coupling system in accordance with the invention; and

FIGS. 3, 4, 5 and 6 illustrate elevational and sectional views of an embodiment of the invention.

In order to describe the principle of the invention, it will be first assumed that each element carries only one electrical terminal and that this coincides with the point of attachment of the connecting device.

FIG. 1 relates to the case of elements A and Bin rectilinear relative motion in respect of each other and FIG. 2 to the case of components which have a circular relative motion about a centre for purposes of explanation, it will be assumed that B is fixed; the arrows F, and F indicate the direction of displacement of the component A. A leafspring R, made for example of beryllium bronze, is attached at its ends respectively to the terminals a and b on the elements A and B, so that during the relative motion, the springstrip rolls on the corresponding walls of A and B, without any sliding.

Where the elements A and B are not suitably designed;

to permit this rolling motion to take place, respective components, suitably designed, aremade integral respectively with these elements, references A and B being now used to designate the component parts on which the springs roll.

In the case of FIG. 1, the mutually opposite walls of A and B are therefore retilinear, parallel to the direction of displacement. In the case of FIG. 2, these walls are circular and concentric. The springs are fixed, for example inserted, at a and b in FIGS. 1 and 2; however, it goes without saying that the terminals 0 and b may as well not be located on the mutually opposite faces of A and B: in all cases, the points of casing must be in permanent electrical contact with the terminals. With the exception of the points of attachment, there is no electrical contact between the springs and the components A and B, either because the springs are covered with an insulating film or because components A and B themselves are made of an insulating material. It goes without saying that 11 pairs of terminals such as those a, b can be provided, which may be interconnected by an appropriate number of respective springs. In both cases, i.e., that of rectilinear motion and that of circular motion, the radius of curvature r of the springstrip remains constant: the elastic energy stored in the spring. remains constant in the first case, where there is no couple; in the second case, it varies a little because of the variation of the lengths of the spring portions having respectively the radii of curvature R and R The radius of curvature r will be made sufficiently large to keep the elastic stresses low: under these conditions, the springstrips roll on the walls A and B without slip.

FIG. 3 is an elevational view of an embodiment of the invention. In this example, the two components A and B are concentric and in a relative circular motioninrespect of each other, the components comprise 12 pairs of terminals a b a b the terminals a, ( i 1,2...n) being fixed to the component A and the terminals b, to the component B. It is assumed that the relative movement between the two sets of terminalsis an alternating movement limited to an angle of 1- 35.

The spring blades are arranged in two axially offset groups; one of the groups comprises-the springs R,, R R R R and R coupling the. terminals ag, b',.of odd order i,.whilst the second group comprises the springs R R R R R and R which couple the terminals of even order i; the springsof the two groups are. in thisexample staggered in a circular sense, thus avoiding-interleaving of the connections of the two groups. of springs.

Of course, this is not an essential. feature; the springscouldi equally-well not be staggered. at all: it would merely suffice to extend the. electrical contacts of the. points of attachment of the. springs in one:of thegroups, in order to connect them to-offset terminals. Also, and. this depends essentially upon the application desired, the terminals associated with the two groups couldibe. arranged on opposite faces of'theflat' pieces which-here: constitute the components A and. B;

For example, the terminals (1 b, could be soldered to.

studs 0,, d, themselves soldered. to. printed circuits 011 the respective pieces A and B;

FIG. 4 diagrammatically illustrates a section in a planepassing through the shaft X'to whichthecompo nent Bis fixed; in order to simplifythefigure, it will be. assumed here, that the two groups are. not angularly, offset from one another; the. drawingiis: not' to-scale: This figure simply illustrates the. axial. offset between the two groups of leaf-springs; the attachment, connection and insulation details of the springs, have not been illustrated. It is assumed that the springs a, and a, 1 are fixed in the same plane of section.

In reality, because of the axial offset or stagger between the two groups, only one spring can be seen at a time in a section taken in a plane passing through the axis; the springs of the two groups can be seen in FIG. 5, the latter being a sectional view through the device of FIG. 3 on halfplanes defined by (10 and B respectively.

In this example, the springs of one and the same group are identical with each other but this of course is not a characteristic feature of the invention; in particular, the width of the springs will be determined by the current which they have to carry. The springs are guided by the faces of the casings, so that there shall be no friction on the lateral surfaces. The odd number springs, being designed in this example to carry the heavier current, are wider than shown in FIGS. 5 and 6 and they are also longer.

Grooves are formed in the components A and B at 1 1 and 21 for the springs of the first group and at 12 and 22 for those of the second; these springs roll within these grooves. The springs are soldered to studs c, and d, ( i 1,2.....n) to which the terminals are attached, so that the leaf of each spring remains tangential to the opposite walls of the rollers A and B ( grooves 11, 21 and 12, 22) as shown in FIG. 6, the latter being a partial sectioned view along the line 7 'y. The terminals themselves are in electrical contact with various elements which have not been shown and, to this end, printed circuits are formed on components A and B as stated hereinbefore.

Self-evidently, the invention is not limited to the embodiments described and illustrated here, purely by way of example. In particular the relative sizes of the spring blades and their attachment on the pieces A and B, may be varied provided that there is not discontinuity into the spring, which, at the attachment points, should be tangential to the walls along which it is to roll. Last, the invention is not limited to the electrical coupling of components which execute a relative linear or circular motion, but applies generally to any move ment in which the potential energy of the elastic springs can be maintained substantially constant, that is to say that the variation in the radii of curvature of the faces guiding the spring strip remains small and that the radius of curvature r of the spring itself remains substantially constant, the shape of the walls on which the spring rolls having to be matched to the movement in question; in all cases, the essential thing is that the coupling springs should roll on the guide surfaces without any slip and that, during this movement, the electric limit of the spring material should not be reached.

What is claimed is:

1. A rotary electrical coupler between two elements relatively rotatable about an axis of rotation over a limited angular displacement comprising, in combination:

a. said two elements each of which include a first element and a second element, said first element being positioned radially inwardly with respect to its associated second element, said first and second elements having respective cylindrical walls concentric with respect to said axis of rotation, said walls having at least one pair of opposite walls which are respectively integral with said first and second elements;

b. a plurality of conductive springs, each of said springs having a U shape forming two ends, two linear portions and a curved intermediate portion, said two ends being respectively attached to said first and second elements, said two linear portions applying pressure respectively on the two opposite walls of a said pair of walls, said springs rolling without slip on said walls during said limited angular displacement and including one group of springs for each of said pair of walls, the springs in each of said groups being staggered regularly and circularly about said axis of rotation; and

c. terminals for connecting said springs, each of said springs being connected by its two ends to two respective terminals for transmitting an electrical datum, said springs transmitting separate electrical data between said elements.

2. A rotary electrical coupler between two elements relatively rotatable about an axis of rotation over a limited angular displacement comprising, in combination:

a. said two elements each of which include a first element and a second element, said first element being positioned radially inwardly with respect to its. associated second element, said first and second elements having respective cylindrical walls concentric with respect to said axis of rotation, said walls having at least two pairs of opposite walls which are respectively integral with said first and second elements;

b. a plurality of conductive springs, each of said springs having a U shape forming two ends, two linear portions and a curved intermediate portions, said two ends being respectively attached to said first and second elements, said two linear portions applying pressure respectively on the two opposite walls of a said pair of walls, said springs rolling without slip on said walls during said limited angular displacement and including one group of springs for each of said pair of walls, the springs in each of said groups being staggered regularly and circularly about said axis of rotation, said springs being distributed in at least two groups offset parallel to said axis of rotation, said first and second elements having separate pairs of cylindrical concentric walls respectively associated with said groups of springs; and

c. terminals for connecting said springs, each of said springs being connected by its two ends to two respective terminals for transmitting an electrical datum, said springs transmitting separate electrical data between said elements.

Claims (2)

1. A rotary electrical coupler between two elements relatively rotatable about an axis of rotation over a limited angular displacement comprising, in combination: a. said two elements each of which include a first element and a second element, said first element being positioned radially inwardly with respect to its associated second element, said first and second elements having respective cylindrical walls concentric with respect to said axis of rotation, said walls having at least one pair of opposite walls which are respectively integral with said first and second elements; b. a plurality of conductive springs, each of said springs having a ''''U'''' shape forming two ends, two linear portions and a curved intermediate portion, said two ends being respectively attached to said first and second eLements, said two linear portions applying pressure respectively on the two opposite walls of a said pair of walls, said springs rolling without slip on said walls during said limited angular displacement and including one group of springs for each of said pair of walls, the springs in each of said groups being staggered regularly and circularly about said axis of rotation; and c. terminals for connecting said springs, each of said springs being connected by its two ends to two respective terminals for transmitting an electrical datum, said springs transmitting separate electrical data between said elements.

2. A rotary electrical coupler between two elements relatively rotatable about an axis of rotation over a limited angular displacement comprising, in combination: a. said two elements each of which include a first element and a second element, said first element being positioned radially inwardly with respect to its associated second element, said first and second elements having respective cylindrical walls concentric with respect to said axis of rotation, said walls having at least two pairs of opposite walls which are respectively integral with said first and second elements; b. a plurality of conductive springs, each of said springs having a ''''U'''' shape forming two ends, two linear portions and a curved intermediate portions, said two ends being respectively attached to said first and second elements, said two linear portions applying pressure respectively on the two opposite walls of a said pair of walls, said springs rolling without slip on said walls during said limited angular displacement and including one group of springs for each of said pair of walls, the springs in each of said groups being staggered regularly and circularly about said axis of rotation, said springs being distributed in at least two groups offset parallel to said axis of rotation, said first and second elements having separate pairs of cylindrical concentric walls respectively associated with said groups of springs; and c. terminals for connecting said springs, each of said springs being connected by its two ends to two respective terminals for transmitting an electrical datum, said springs transmitting separate electrical data between said elements.

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