DE2801260A1 - ELECTRIC CONTACT ASSEMBLY - Google Patents

Description

Patent attorneys ΟίρΙ.-lng. Curt Wallach Dipl.-Ing. Günther Koch Dipl.-Phys. Dr Tino Haibach Dipl.-Ing. Rainer Feldkamp

D-8000 Munich 2 Kaufingerstraße 8 Telephone (0 89) 24 02 75 Telex 5 29 513 wakai d

Date:

Our reference: 16 126 - Fk / Ne

Sperry Rand Corporation
New York, USA

Electrical contact assembly

Ö0962Ö / 06U

Patent Attorneys D: pl.-Ing. Curt Wallach

280126 (1 Dipl.-Ing.Günther Koch

^V Dipl.-Phys. Dr Tino Haibach

Dipl.-Ing. Rainer Feldkamp

D-8000 Munich 2 KaufingerstraBe 8 Telephone (0 89) 24 02 75 Telex 5 29 513 wakai d

D «tum:

Under sign: 16 126 - Fk / lJe

Sperry Rand Corporation New York, USA

Electrical contact assembly

The invention relates to electrical contact assemblies for transmitting electrical energy between two relative components rotatable with respect to one another as well as methods for assembling such contact assemblies.

The invention is particularly, but not exclusively, related on contact assemblies for the transmission of electrical currents between stator and rotor parts of measuring instruments, e.g. between the gimbal frames of gyroscopes that can be rotated relative to one another.

Rolling electrical contact assemblies are known per se and have been suggested for use in place of conventional slip ring and brush assemblies. Such a rolling contact resulting assemblies are, for example, in US patents 2,467,758 and 3,259,727. These However, contact assemblies have not been widely and specifically not by manufacturers of sensitive precision instruments used, e.g. for gyroscopes. The true

809823/0844 '''

The apparent reason is that none of the contact assemblies described in the aforementioned patents is suitable for such applications.

As would be the case for those skilled in the art of gyroscopes is well known, slip rings and "hair wire" brushes, which are held in brush blocks for many years to transmit electrical power and signal currents used between the relatively rotatable gimbal axes of gyroscopes. Although such contact arrangements showed generally satisfactory results, yet they gave rise to serious manufacturing and maintenance problems, which resulted in fairly high failure rates for repairs and overhauls. These contact assemblies are extreme sensitive and require a high level of knowledge during assembly and a time-consuming adjustment, thus a preload is achieved, which corresponds to a minimal sliding friction in environments with vibrations and shocks.

Furthermore, these are contact arrangements that are normally used during a repair and overhaul of the gyroscope exposed, subject to damage during handling. In operation, especially when operated in aircraft, such gyroscopic devices are exposed to vibrations and because a If there is sliding contact between the brushes and the slip rings, there is a risk of abrasion masses building up, which cause an electrical short circuit and / or interruptions, so that a removal of the contact assemblies cleaning and / or replacement is required, which in turn can be difficult, time consuming and costly Process represents. Furthermore, with autopilot systems, the speeds and movements of the aircraft with Using position circles3Ln by differentiating the gyro position signals generate the electrical noise interference that is more common with this type of slip ring contact assembly amplified so that the rate signal in undesirable catfish Interference and requires strong filtering so that

809829/0844

the quality of the rate signal is reduced. In addition, conventional slip rings can be used for digital encoders, for example cause very annoying digital interference. As is known to those skilled in the art of gyroscopes, furthermore, slip ring and brush assemblies reduce the long-term accuracy of gyroscopes due to the relative high torques caused by friction caused by the usually large number of slip rings and brushes which are required in modern electrical gyroscopic devices.

In view of the foregoing it is understood that devices for the transmission of currents between parts of sensitive instruments that can be rotated relative to one another, e.g. between the cardan frame axes of Gyroscopic devices should have the following desirable properties as far as possible: friction values and values of the clutch torque of substantially Oj, relatively stable current transmission even in shock and vibration environments; long reliable service life, low manufacturing and assembly costs and no vibrational sliding friction contact, so that the build-up of abrasive masses is eliminated.

The rolling electrical contact assemblies according to the US patents mentioned at the beginning may be used for some applications although they have not found general application in industry, they are suitable for institutions unsuitable that require low friction and low clutch torques and where it is required is that self-holding forces are generated without varying coupling torques between the two relative to each other rotatable parts are introduced.

For example, in U.S. Patent 2,467,758, a Roller strip conductor for use as a "slip ring" for an AC motor and as a rolling contact for an electrical

80982Q / 08U ./.

tric switch potentiometer or a rheostat described. It can be seen that in these applications friction or Coupling torques generated by the roller bandIelter itself together with its holding mechanism, do not represent a design point of view, because in all Cases a contact part is driven by a mechanical power source. In some applications, for example sensitive instruments such as gyroscopes carry whatever is caused by the electrical contact assemblies Friction to an undesired torque on the mounted component, so that an undesired drift or precession is caused and the effectiveness of the gyro as an accurate long-term reference is reduced. Will continue in the known rolling contact assembly, the roller strip conductor does not by itself on its orbital path between the conductor rings but requires retaining flanges or pin and hole retaining assemblies. Such flanges or Pin-hole retainer assemblies and the like are completely useless in some applications because they are tall Cause frictional torques and a changing clutch torque amplitude caused by the bands that connect to the flanges or the pin and hole surfaces come into contact or rub against them while the contact assembly rotates. If a number of electrical Circling is required, this high and changing torque is multiplied accordingly, so that these arrangements are completely unsuitable for low torque applications. Furthermore, these are known Contact assemblies the ratio between the free diameter of the contact ring and the radial distance between the inner and outer conductor elements very large, so that when the contact ring is compressed in the radial gap becomes, this contact ring is very badly dented, resulting in a clutch torque hysteresis as well as a premature metal fatigue and breakage. Furthermore, this deformation can be one bulging and another non-uniform Produce torque. Therefore, a contact

809829/0844 /

ring, which is severely deformed when assembled, is not suitable for applications in which a coupling torque of substantially O is desired or required.

The further cited US Pat. No. 3,259,327 describes a flexible current transmission component which has a rolling element and in which the current transmission properties are said to be improved over the aforementioned US patent. This improvement is to be achieved in that the conductive rings of the relatively movable parts are designed in the form of a deep or pointed ^M V ^M , so that the roller contact element wedges itself into the V-shaped groove, so that a sole process is achieved to get good electrical contact. The contact ring of this US patent is formed by a small diameter spring which is self-contained to form a circular ring, the diameter of which is very large compared to the radial distance between the V-shaped grooves, so that the circular ring in assembled condition forms a severely deformed rolling element which wedges itself into the steep V-shaped walls, so that a high clutch torque is generated. As an alternative, a flat band is described, but this band, like the circular spring ring, wedges between the steep side walls of the V-shaped groove. It can be seen without further ado that this contact assembly is completely unsuitable for applications in which it is necessary that very little friction and very low coupling torques are exerted by the contact assembly on the supported rotatable components, because in this known contact assembly a very large one Sehleif- or sliding friction force and uncompensated bending moments occur, which are generated when the tongue or tape enters or leaves the V-shaped grooves.

It is therefore to be noted that the known elements with rolling working contact assemblies not designed in such a

809829/0844 ./.

can be that they have low friction and low clutch torques. Furthermore, this is known Contact assemblies give no indication of how the circular rings or contact rings in the radial gap can be installed between the conductor rings.

The invention is based on the object of providing an improved contact assembly for the transmission of electrical power and / or to create signals between two relatively rotatable parts in which efficient and reliable transmission is possible of electrical energy at substantially zero friction and clutch torque between the two rotatable parts results.

According to a basic idea of the invention, an electrical contact assembly for the transmission of electrical energy between two components rotatable relative to one another about a common axis is created, which is characterized in that first and second circular coplanar electrically conductive rings are provided, that one of these rings on one of the components is arranged, while the other ring is rotatably arranged on the other of the components about the axis, that the respective diameters of the rings form a relatively large radial gap between these rings, and that at least one of the mutually facing surfaces of the rings has a relatively flat arcuate concave shape in the direction of the gap that an elastic wire-shaped electrically conductive circular ring with a free diameter which is larger than the gap and with a generally flat outer surface is provided that the circular ring is compressed in the gap, so that the circle sring rolls on the or each concave ring surface substantially without friction during a relative rotation between the components and that the circular ring in this way pretensioning forces between the flat circular ring surface and the or each concave ring surface with force components in such directions

809829/0844 * ^A

creates that the annulus is held within the or each concave surface.

According to a further basic idea of the invention, a method of assembling the inventive Contact assembly created the steps of attaching one of the rings to one of the components such that it is of from a normal coaxial position with respect to the other ring into an eccentric position with respect to this component is so that a larger gap is formed on one side of the other ring, which is larger than the free one The diameter of the annulus is, while a smaller gap is formed on the opposite side, of the movement of the one ring in the eccentric position, the insertion of the circular ring in the larger gap, the alignment of the Annular ring such that it is substantially coplanar with the inner and outer rings, and the movement of the a ring in the normal coaxial position such that the annulus is between the inner and outer rings is squeezed.

Further advantageous refinements and developments of the invention emerge from the subclaims.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing.

In the drawing show:

Fig. 1 is a sectional view (along the line 1-1 to

Fig. 2) an embodiment of the contact assembly, the one on one of the gimbal axes of a gyroscope is used;

Fig. La is a schematic plan view of a typical gyroscope;

809829 / 08U

-H-

Pig. Figure 2 is an end view of the contact assembly of Figure 1 with a protective cover removed;

2a is an end view of the contact assembly suitable for

the installation of the circular rings or contact rings is prepared;

Figure 3 is a sectional view taken along line 3-3 of Figure 2;

Fig. 3a is a fragmentary view showing part of the Assembly according to FIG. 3 when considering its shows right end;

4 is a greatly enlarged view of typical circular ring-conductor ring interfaces;

Figure 4a is an illustration showing the generalized geometry of the annulus / ring interfaces;

Fig. 5-8 representations showing the force vectors and the moments through which the annulus or the contact ring aligns itself and is held by itself;

9 and 9a representations which are used to explain the basic ideas of the invention are appropriate;

10 and 10a further sectional views to explain the method according to the invention.

In the following, reference is first made to FIG. 1 a, in which a vertical gyro unit IO is shown schematically although it will be understood that the invention is applicable to any instruments employing electrical contacts with low torque between relative to each other

809829/0844

rotatable parts are desired. The gyroscope 10 has a rotor 11, which with the help of suitable (not shown) Pivot bearings is rotatably mounted in a rotor housing 12 and at high speed around a normally vertical Axis 13 revolves. The rotor 11 is in turn in a normal horizontal cardan frame 14 mounted about a first normally horizontal axis 15 and the cardan frame 14 is in turn mounted in a fixed housing 16 about a second horizontal axis 17 perpendicular to the first axis 15.

It is well known that when the rotor 11 is rotated at high speed and when the bearings supporting the housing 12, as well as the gimbal 14 and electrical contact assemblies, have zero torque coupling, the rotor axis of rotation maintains its position in space indefinitely . Signal generators are normally arranged on the gimbal axes and signals proportional to the deviations of the housing 16, for example of an aircraft, from the horizontal plane can be generated and used for aircraft control and / or display purposes. Such generators are shown schematically at 18 and 19 in Fig. La. Because a smooth mounting of the gimbals is not possible, it is necessary to exert torques on the gimbals in order to align the rotor to gravity reference values and to achieve other control purposes, these torques being exerted with the aid of torque transducers 20 and 21, which are shown schematically are. The rotor housing 12 is usually mounted for rotation about the axes 15 and 17 with the aid of precision ball bearings 22 (Pig. 1). Because modern gyroscopes are usually powered electrically, i. E. the rotor is driven by an electric motor and the signal generators 18 and 19 and the torque transducers 20 and 21 are also usually electrical components, devices must be provided to provide electrical power and electrical signals between the housing 16 and the gimbal frame, which can be rotated relative thereto

809829/0844

as well as to be transmitted between the cardan frame 14 and the rotor housing 12, which is rotatable relative thereto.

So far, this electrical energy transfer has been carried out with the help of a number of insulated slip rings on attached to a journal extending from the bearing support structure, a corresponding number is attached by brushes to a brush block which is arranged on the support structure. Each of these brushes is common Formed by two very delicate springy wires that are carefully bent to make a pressure contact (and thus frictional contact) with the opposite sides of the slip ring. Because usually a big one Large number of circuits for operating the gyroscope is required and these circles must each have a contact arrangement, it is necessary to have one to use an appropriate number of slip rings and brushes, so that the frictional torques are multiplied. As is well known, the axis of rotation of the gyroscope tends to drift from a reference position at a rate determined in large part by frictional torques applied to gimbal axles 15 and 17 occur. The precision ball bearings contribute to this free gyro drift rate to some extent, but are based the greatest contribution on the slip rings and brushes.

If the contribution of the clutch torque of the electrical power transmission devices could be reduced almost to zero, there would be a considerable improvement in the quality of the gyroscope. This reduction is one of the aims of the described embodiment. Furthermore, because many gyroscopes are used to stabilize and steer vehicles, they are subject to shock and vibration in this vehicle. It has been found that in such applications the brushes tend to slide on the surfaces of the slip rings, with the result that abrasive masses are deposited on each other

809829/0844 ./.

Form contacting surfaces that actually lift the brush from the slip ring after a certain time can, so that an interruption is caused. The gyro must then be periodically put out of operation and has been overhauled, so that the costs for the owner of the gyro device are increased. Another goal of the described Embodiment is therefore a power transmission device to create that does not have this abrasion mass problem.

As mentioned earlier, the brush and slip ring assemblies are extremely delicate; they require great care is taken in the initial assembly so that manufacturing and maintenance costs are increased. Farther the assembled device must be handled with great care so that the exposed sensitive Brushes are not damaged. The embodiment described is therefore intended to provide an electrical power transmission assembly that is easy to assemble and that is fully protected and shielded.

In Fig. 1 an enlarged partial section of the gyroscope according to Fig. La is shown, in particular the electrical Energy transmission device is shown associated with the bearing between the cardan frame 14 and the housing 16 is. As shown, the card frame 14 is in the stationary rotor housing 16 in the precision ball bearing 22 about a bearing pin 25 of the cardan frame 14 umdie Axis 17 rotatably mounted. The bearing pin 25 is hollow and has a channel for electrical leads from the electrical contact assembly. An extension 28 of the bearing pin 25 along the axis 17 results in a fastening arrangement for an inner circular conductor, as this will be explained in more detail. Two clamping nuts 29, 29 ′ are screwed into the housing 16 and onto the extension 28 and serve to clamp the ball bearing 22 in place.

809829/0844

The electrical contact assembly 30 is used to transmit electrical power and / or signals between the stationary Housing 16 and the cardan frame 14 rotatable relative thereto, with a friction and clutch torque of essentially 0 can be exerted on the sensitive gimbal frame. The contact assembly 30 includes an outer cylindrical housing 31 (preferably made of insulating material such as molded plastic material) with a mounting flange 26, the is attached to the outer end surface of the housing 16 by means of screws 27, 27 'via an adapter plate 24. Washers can be added if required is to achieve alignment of the ladder rings. Uniformly along the inner surface 32 of the housing 31 a number of circular concave conductor rings 33 is distributed, which are referred to below as outer conductor rings will. Each ring, as shown in greater detail in FIG. 4, may be made of a gold alloy, conventionally is used for such applications and applied by electroplating to the concave grooves 33 of the housing 31 is applied, with a electrical connection is made with a corresponding electrical connection pin 34 which is in the housing 3I is molded to achieve an external circuit connection.

An inner cylindrical member 36, also made of molded plastic insulating material, is in the journal extension 28 (for example by epoxy glue) attached. Along the outer surface 37 of the cylindrical part 36 is a corresponding number of circular concave conductor rings 38 uniformly distributed, hereinafter referred to as inner conductor rings are referred to. Each ring 38 is preferably made of gold obtained by electroplating the corresponding concave surfaces 38 'of the part 36 are applied and electrically connected to a corresponding electrical Conductor (for example a wire) 39 connected

809829/0844 * ^A

which is embedded in the part 36 for circuit connections to manufacture electrical components carried by the gimbal 14. Every inner ladder ring is arranged on the part 36 so that it is precisely aligned with a corresponding outer conductor ring 33 on the housing 3I so that a number of ring sets 33, 38 are formed with the two rings of each set within of machining tolerances concentric and coplanar are and washers are inserted in the required manner between the adapter plate 24 and the housing l6.

The relative diameters of the ring sets, i.e. the inside diameter of the surface 32 with respect to the outer diameter of the surface 37, are selected so that a relatively large Radial gap 41 is formed between the two concentric rings of each set. To the contact assembly 30 opposite Sealing off dust and other contaminating materials and providing protection during handling is a Plastic cover 43 on housing 31 by means of spring tabs 44 fastened in the manner of fastening a hub cap.

A corresponding number of elastic, electrically conductive thread-like or wire-like circular rings or contact rings 42 are arranged in the radial gap 41, one contact ring 42 being provided per ring set 33 * 38. The outer generally flat surfaces of the contact rings 42 contact and roll over the conductive concave surfaces of the concentric conductor rings 33 and 38 so that an electrical connection between the terminal pins 34 and the electrical components on the gimbal 14 via the conductors 39 is made. The critical design parameters of the conductor ring surfaces and the contact ring properties are discussed in more detail below. The main considerations that determine the selection of these design parameters consist in reducing any torques as far as possible, which are caused by the contact ring

809829 / 08U

Lelterring-Orenzflfiohe exercised on the cardan frame 14 the greatest possible enlargement of the self-holding properties of the Kontaktrlng-ZLelterrlng-Grenifläohe if steps and vibrations occur without significant Increase in the coupling torques as far as possible Enlargement of the power supply properties of the contact ring / Conductor ring surface and the greatest possible increase in the randomness and service life of the contact assembly.

FIG. 2 shows one end of the contact assembly 30, which is the normally required arrangement of the contact rings 42 (after a certain period of operation) in the radial space or gap 41. It can be seen from FIGS. 1 and 2 that the sensitive high contact rings 42 and the conductor rings 33, 38 are all located within the contact module housing J51 and are therefore not exposed, so that no undesirable effects occur during normal handling of the sensitive gyroscope Touching or jumping out of the contact rings can occur.

4, there is shown a greatly enlarged detailed view of two typical contact ring / outer conductor ring interfaces. The contact ring / inner conductor ring interfaces can be essentially the same. The arcuate concave surface of the conductor rings 33 results in an automatic catching and holding of the contact rings 42, the depth of the concavity being selectable depending on the strength of the shocks and vibrations that can occur during operation of the gyroscope, as will be explained below. It will be understood that in some applications this arcuate surface need only be formed in one of the concentric conductor parts if the intended application does not result in high stresses. After the concave grooves 33 ^f are machined with the desired radius and depth.

809829/0844

belted or otherwise formed, they can be suitably covered and the gold alloy is electroplated onto the groove or concave surface to the desired thickness, typically 2/1000 mm (80/1000 of an inch) ) to form the conductor rings 55. The connection pins are cast into the molded housing 11 and carefully exposed by machining the groove so that the gold is deposited on these contact stubs and the contact pins form an external electrical connection possibility for the gold rings 55. If so desired, alternatively separate copper rings can be cast into the plastic housing 51 and then machined to the desired concave shape, whereupon nickel and gold (or other suitable material combinations) are successively evaporated, for example, to form the concave conductor rings 55 . Each contact ring 42 is also plated with gold, as shown in FIG. 4, to improve the electrical conductivity of the contact assembly.

The contact ring retention properties of the assembly can be easily adapted to a wide range of vibration and shock loads without any constraints from assembly considerations. If, for example, the measuring instrument having the contact assembly is to be operated in a quiet or favorable environment, the depth of the grooves y? be very shallow, as indicated by the dashed line XX of Fig. 4, which shows a small arc length, while on the other hand, if the vibrations and shocks are very strong, it may be necessary to increase the groove depth, ie the arc length increase, as indicated by the dash-dotted line YY, in order to prevent the contact ring from jumping out. It should be noted, however, that the relatively flat radius of curvature remains the same for both cases. The lines shown in full

· /. 809829/0844

The illustration shown in FIG. 4 is a typical construction for operation with moderate impacts and vibrations, as is to be expected, for example, in applications of gyroscopic devices in aircraft. For example, for an aircraft gyroscope, the radius of each groove was 53 * 0.625 mm (0.025 inch), while the groove depth (for a 4.8 mm / 0.19 inch diameter metal alloy contacting, had a diameter of 0.5 ma / 0.02 inch and with a preload of 9.07 g / 0.020 IbB. 0.02 mm / 0.008 inch and one of the contact rings x 42 popped out when the contact assembly vibrated at random with an amplitude of zero , 2 g / Hz.

Although the preferred embodiment of the invention has been explained and described on the basis of sensitive instruments such as gyroscopes, in which in most cases the contact assemblies are very small, there are many other applications in which the contact assemblies must be considerably larger and still have their own -The contact assembly must have holding and catching properties. Thus, the geometry of the ring concavity, the contact ring dimensions and the radial gap can be generalized to accommodate a variety of applications in the following manner, for which purpose reference is made to Figure 4a. In general, the radius of curvature of the conductor ring surface or groove R "should be equal to or smaller than half the dimension of the radial gap, ie

where R _{Q is} the radius of the contact point of the contact ring with the outer conductor ring as defined below and R _{1 is} the radius of the contact point of the contact ring with the inner conductor ring, as defined below.

The dimensions of R and R ₁ are complex functions of the groove radius and the contact ring width, as can be seen from the following

809829/0844

The following equations give:

^R 0 - ^R IG ^{+ R} G I ¹ - ^Cos ^ ^Tan ^ J < ²⁾

and

^R I * ^R 0G * 0 ^R G ^l - Cos

(Tan " ¹ ψ) \ O)

therein R _{IQ is} the radius from the axis 17 of the contact assembly group to the bottom of the inner annular groove, R _{00 is} the radius from the axis 17 of the contact assembly to the bottom of the outer annular groove, and W is the width of the contact ring.

Furthermore , the axial restoring or self-relieving forces F ^, which are caused by the contact ring conductor ring height , can be expressed as follows!

^P AH- ^f

- R.

I I 1

if

C-

¹ ^ l

2R ₀

Looking at the construction of the contact ring 42 it should be remembered that, as stated above, when the contact ring is installed in the radial gap 41, the free diameter of the contact ring is greater than the radial distance between the conductor rings, the The ratio of the free diameter to the radial distance determines the preload on the contact ring. This relationship is chosen so that a clearly rolling and thus essentially frictionless contact of the contact ring with the conductor ring surfaces is achieved with a relative rotation between the cardan frame 14 and the housing 16. This Criterion is explained in Fig. 9, in which the properties of contact ring 42 are selected to maintain exclusive rolling contact with rings j5j5 and 58. As explained in more detail below

809829/0844

it can be seen that to achieve point contacts between the contact ring surface and the conductor ring surfaces the contact ring diameter is theoretically exactly the same the dimension of the radial gap £ i.e. the asymptote Fig. 9. This is of course not practical, in particular then not when shocks and vibrations occur. There must therefore be a compromise between the theoretical and the practical contact ring properties, as explained below.

It has been found that when the maximum free diameter of the contact ring is exceeded, the contact ring is deformed during its assembly between the conductor rings that the contact ring surfaces the conductor ring surfaces do not touch uniformly and that the contact ring surfaces between the ring ends try to each other bulging or bulging away from the adjacent ring surfaces so that there is positive contact ring contact at four points along the contacts ingobe surface shows how this is indicated in the upper part of FIG. Due to the geometric relationships, this means that no real There is rolling contact between the contact ring and the conductor rings, so that sliding occurs at the interface, so that frictional torques are caused. This exaggerated "kidney" or "bean" shape continues to work in the Meaning of an overstressing of the contact ring material, so that a material fatigue and a breakage of the contact ring after a relatively few revolutions, so that the life expectancy is unacceptably short. In particular, calls such an exaggerated "kidney" or "bean" shape of the built-in contact ring when the components are rotated uncompensated moment in the contact ring with a resulting increase in clutch torques. This can be seen as a torque dependence on the angular position of the contact ring around the gap.

809829/0844

In most practical applications of the contact assembly described, and particularly in applications for gyroscopes is an absolute and continuous concentricity between the inner and outer conductor rings due to the Properties of the bearing ball bearing, the machining tolerances and a flexibility caused by environmental influences of the device cannot be achieved. Therefore, the contact ring diameter is selected to have the desired preload at the maximum eccentric gap position during such anomalies. This means that at the minimum eccentric gap position, the preload on the contact ring is greater than desired. When the contact ring has too large a free diameter, the radii of the ends of the contact ring are not the same and coupling torques are transmitted from the contact ring to the rotatable part exercised. This is exaggerated in the upper part of FIG. 9 by the position shown with dashed lines kidney-shaped contact ring shape shown. Hence the one you want free diameter of the contact ring such that these radii of the contact ring ends are essentially the same remain even during operations where the conductor rings are not precisely concentric.

To the desired contact ring Z conductor ring contact preload without achieving buckling, a number of interrelated contact ring parameters must should be considered. In general, the radial dimensions of the gap (R - R,) and the axial width of the W of the contact ring are through the desired basic Dimensions of the contact assembly established; for example, in one embodiment the radial dimension was of the gap about 5 nm and the axial width W des Contact ring was on the order of about 0.5 mm. Second, the contact ring material is selected. This selection is based on a number of requirements including resistance to deformation that a material has with a requires high modulus of elasticity, and the ability to do without

809829/0844 ^{β /}

2801280

To be deformed fracture, so that a material having a high yield stress is required. In one embodiment, a material successfully used was a 95 # nickel alloy with a Young's modulus of 2.11 x 10 -4 kg / cm (30.10 psi) and a yield stress of 14,000 kg / cm ² (200,000 psi). Such an alloy can be obtained from Mechmetals Corp., Culver City, California. After the above parameters have been selected as constants, the remaining dimensions to be determined are the free radius R _{p of} the contact ring and the radial thickness t of the contact ring in order to achieve the desired contact ring / conductor ring preload F _n when the contact ring is around a Amount Y _{T is} deflected into the gap 41 during assembly.

At this point it should be noted that in the inventive Assembly method as well as a wide range of parameters is possible for the contact assembly to suit one to meet a wide range of environmental requirements. For example, without the assembly method according to the invention the maximum free diameter of the contact ring, the contact ring material and possibly its thickness combined with the depth of the concave conductor rings limited by the amount by which the contact ring must be deformed in order to make it to be inserted in the radial distance between the conductor rings. Due to the assembly method according to the invention most of the contact ring and groove design parameters are not limited by mechanical assembly or constraints.

The preload force can be approximated by the following equation;

(5) F /

is in it

Y _T - contact ring deflection,

809829/0844 ./.

E = modulus of elasticity of the contact ring material Wp = contact ring width
t = contact ring thickness

R "= free radius of the contact ring.

Jt?

9 is a diagram of the contact ring thickness t versus the free radius Rp of this contact ring (where the contact ring width Wp is now continuously 0.5, R _Q - R ₁ is 3.8 mm and where the modulus of elasticity is 2.11 · 10 kp / cm, while the yield stress is 14100 kp / cm) for a group of curves with constant preload F ^. It can be seen that the maximum preload or preload is a function of the size of the contact ring and conductor ring diameters, and that the maximum desirable preload occurs for a free radius of the contact ring of approximately 2.916 mm (0.115 inches). It can also be seen that for free radii of the contact ring that are larger than the maximum desirable radius, the preload leads to undesirable contact properties, ie bulging, while for radii smaller than this maximum desirable radius, of course, larger than R _Q - R ₃ . are, the preload results in the desired contact properties, ie a pure rolling contact. Therefore, if the parameters R _Q - R ₁ as well as W are determined by basic design reasons, any desired preload F _n can be determined; see for example the point B of FIG. 9, which shows that, at a predetermined contact ring thickness of for example 0.0228 mm (0.0009 inches) at a desired preload of 9 ₄ O7 P (0.020 lbs) of a free radius of the contact ring of 2 .44 mm (0.096 in) is required. If a higher preload is desired, for example 13.6 ρ (0.03 lt »s), the free radius can be maintained and the thickness increased to about 0.035 mm (0.0013 inches). It can be seen that for the selected thickness there are two free radii (A, B according to FIG. 9) which give the desired preload, but one is

809829/0844

2801280

Free radius (B) so large that it causes undesirable buckling of the contact ring when it is inserted into the gap will. In general, it is best to keep the contact ring deformation small by selecting the strength is that a predetermined preload is achieved in order to achieve an optimal contact ring bending moment compensation in this way to maintain, which leads to a minimal dependence of the torque on changes in the radial gap.

In the following, the self-locking and holding properties of the contact assembly having a rolling contact ring are described with reference to FIGS. 5 to 8 again with reference to the groove geometry according to FIG. 4a. As has been shown, these self-locking properties are achieved without the use of V-shaped grooves or vertical guide walls on either side of the ladder rings because such walls would introduce significant coupling torque in use. Concave relatively shallow grooves on at least one of the relatively rotatable parts cooperate with a generally flat outer surface of the contact ring 42 in such a way that force vectors (due to the preload) are generated which act on the contact ring in such a way that it is held within the grooves. These forces are generated during rolling contact and therefore only contribute insignificant coupling torques between the rotatable components. Furthermore, this self-holding property extremely advantageous of the contact ring, if the grooves of one component are not precisely aligned with the grooves of the other component or exactly coplanar with this, so that the manufacturing cost can be reduced (as it was mentioned above, can be simple washers can be used to achieve this alignment with sufficient precision.) Furthermore, the contact rings are held in the grooves by these jerks during operation when normal movements of the gyro or the aircraft in the sense of a displacement of the contact rings in the axial direction relative to the Slot center acted *

809829/0844 ^<A

Figures 5, 6, 7 and 8 show three typical cases of misalignment or disruption of the alignment of the contact rings with respect to the conductor rings. 5 shows a lateral or axial displacement of the contact ring (possibly due to a steady curve of the aircraft). The force vector generated by F _n under these conditions includes lateral or axial components that cause a restoring force and act to return the contact ring to an equilibrium force position. In Fig. 6 an axial misalignment is shown (caused, for example, by a non-planar condition between the inner and outer rings.) In this case too, an examination of the force vectors involved shows that resultant force components are generated which act so that the Contact ring is held centered in the grooves. Finally, as shown in Figures 7 and 8, any twisting misalignment θ results in the generation of restoring moments M due to the points of contact of the flat surface of the contact ring with the concave surface of the conductor ring. FIG. 7 shows a case in which the contact ring has carried out an angular movement around a radius of the assembly, while FIG. 8 shows a case in which the contact ring has carried out an angular movement out of the plane of the axis of rotation.

At this point it should be noted that a right-angled groove or a V-shaped groove regardless of whether this groove is flat or is deep, the self-catching forces described above are not can generate when the conductor rings are misaligned in the axial direction. Such axial misalignments can occur accidentally during the operation of an aircraft gyroscope when g-forces occur during flight. A right-angled groove cannot generate such restoring forces because the contact ring only counteracts the side walls of the groove abuts, so that a deformation of the contact ring and the generation of high frictional torques results. Similarly, with a V-groove, itself leads to

809829/0844 /

a shallow groove, axial misalignment of the ladder rings to forces that are actually divergent, i.e. instead of acting in the sense of restoring the contact ring into the groove, these forces act in such a way that the contact ring is pushed out of the groove.

The combination of the concave groove and the flat outer surface of the contact ring results in redundant contact ring contact points, so that a reliable electrical transmission is ensured.

The working with the rolling contact ring contact assembly is designed so that the sensitive contact rings 42 in the radial gap between the inner and outer concave conductor rings 33 »38 without deformation, overstretching, scratching or other damage to this contact ring can be installed. This is extremely important because if the contact ring when handling it, for example with tweezers or the like, only a little is scratched or notched, each Contact ring surface imperfection becomes a cause of torque changes and continues to be the possibility of one Breakage at this point can result after a short period of operation.

Furthermore, without the assembly method according to the invention and the associated device, the contact rings would have to be deformed using some type of spreader tool to insert them into gap 41 can. The spreading tool itself could be the contact ring scratch or nick. In addition, such a tool would be a very skilled person to use prerequisite for assembly so that the contact ring is inserted into the gap and aligned with the conductor rings, which is an extremely difficult and time consuming process represents. The assembly method according to the invention and the associated device eliminates all of the above assembly problems, so that the procedure can be carried out in a very short time by people with little experience,

809829/0844

^"31-2801280

as this will be explained in more detail. The assembly method according to the invention and the associated device furthermore advantageously enable the installation of contact rings with different free diameters or preloads in concave inner and outer conductor rings with different depths depending on the strength of the vibration and shock loads of the device in which the contact assembly is installed.

The assembly process and the associated device are explained below with reference to FIGS. 2, 2a, J5 and ^ a. The method includes the use of an adapter plate 24 and an assembly tool or fixture 50 (Fig. 5). As mentioned above, the adapter plate 24 is fitted between the housing j51 and the instrument housing 16. A number of different adapter plates can be designed for different gyro shapes. The adapter plate 24 is generally circular and includes an inner annular lip 51 which finally fixes the conductor assembly relative to the gyro housing bearing and the journal opening 52 and aligns it concentrically therewith. The outer surface 53 of the adapter plate 24 has an outer recess 54 which receives an inner shoulder j5j5 (Fig. 1) of the housing 3> 1, the shoulder 55 over the holding or fastening flange 26 to the depth of the recess 54 of the Adapter plate extends. The flat recess 54 forms a first substantially semicircular stop 56 (FIGS. 2a and 3) which is concentric with the lip 51 and the opening 52 and which is also concentric with the outer peripheral surface of the housing 3I , so that the normal assembled concentric position of the Housing j51 is set with respect to the ring part 36. The planar recess 54 extends beyond the normal position of the housing Jl opposite to the stop 56 and forms a second radially offset, substantially semicircular stop 57 which is concentric to the outer peripheral surface of the housing, so that a position for

809829/0844 ^{m /} '

the housing 31, which is eccentric with respect to the inner conductor part 36, is fixed. The overall shape of the recess 54 makes it possible to pivot or rotate the outer conductor housing 3H about one of the screws 27, 27 'securing the assembly, for example about the screw 27, so that a pivoting from a normal or closed position concentric to the inner Ladder portion 36 is possible to an open or "loading" position that is eccentric with respect to portion J> 6 . Therefore, in the "loading" position or the open position, a relatively large radial distance is formed on one side between the inner and outer conductor rings of the contact assembly. This large radial spacing allows the various diameter contact rings 42 to be installed. Indeed, this arrangement can allow contact rings of a diameter to be installed which will give the maximum preload (without buckling as described above).

Instead of pivoting the housing 31 about one of its fastening screws according to FIGS. 2, 2a and 3, the recess 54 of the adapter plate 24 according to FIGS. 10 and 10a can alternatively be designed eccentrically with respect to the bearing pin and the inner conductor part 36 and an extension 31 'of the housing 31 can fit into the recess 54 and be set correspondingly eccentrically with respect to the inner axis of symmetry of the housing 3I, so that in its normal position the inner axis of symmetry is aligned with the axis of the inner component 36. Therefore, a rotation of the adapter plate 24 (before inserting the fastening screws 27, 27 ') offsets the housing 3I eccentrically, so that the increased radial distance for installing the contact rings is formed, as shown in FIG. 10a is shown.

The contact ring installation device or tool 50 is shown in FIGS. 2, 3 and 3a and, when used, enables rapid installation of the contact rings

./. 809829/0844

without handling these contact rings with tweezers or other sharp objects that scratch the contact rings or notch. The tool 50 is preferably molded from a suitable plastic material and has a circular base splash section 6o with a diameter which is larger than the inner diameter of the housing 31 » so that this Planschteil can bridge the housing and the axial surface of the housing Jl as an alignment stop for the Tool serves when this is used. An extension or hub 61 and a button 62 on one side of the base flange enable easy handling and operation of the tool. From the center of the opposite side of the Base flange 60 extends a hollow cylinder or guide part 6j with an inner diameter which has a sliding fit the inner conductor part 36 enables and a sufficient Has length so that this guide part extends beyond the inner conductor 38 of the part 36 which is located furthest inward extends. A part of the side of the guide part 63 that on the enlarged gap 41 is directed, is cut away at 64 according to FIG. 2a, so that an engagement of the contact rings with the inner conductor rings 38 is made possible. Laterally offset with respect to the guide part 63 and opposite to the cut-away part of this guide part, a rod 65 made of plastic material is arranged, which with Sliding fit in a mounting hole 66 in the extension or hub 6l is fitted. How to recognize this 3sb shows the rod 65 has a diameter which is substantially smaller than the normal gap 41 and the rod is at one end provided with a number of recesses 67 which have a spacing corresponding to the ring spacing while on the other A button 68 is arranged at the end of the rod. Suitable low pressure ball detent assemblies 69 are provided in order to define clear rod positions when using the tool. However, it is understandable that the rod 65 can be used alone, with the person performing the assembly manually inserting the rod the enlarged gap 41 introduces.

809829 / 08U /

by;

During assembly, the person in charge of the assembly shakes some contact rings out of their containers, preferably in a clean, dust-free room, onto a soft, fiber-free surface (such as foam rubber or foam plastic material) and using the tool 50 with the rod 65 in the extended latching position (whereby the recesses 67 are aligned with the ring pairs during assembly, as described herein) at least the number of contact rings to be loaded onto the rod end is accommodated, whereupon the tool is actuated, for example by tapping, so that one contact ring is free in each of the recesses 67 depends. The end of the cylinder or guide member 63 is then placed on the outer end of the inner component 36 with the axis of the inner component J> 6 oriented horizontally and rotated so that a mark 70 on the plate 24 with an arrow 71 on the flange 6O is aligned (so as to ensure proper alignment of the rod 65 with the enlarged radial opening 41) whereupon the tool 50 is moved fully forward until the inner surface of the flange 60 abuts the outer surface of the housing Jl. Now, all of the contact rings are coplanar with their respective inner and outer conductors rings J5, aligned 38th The housing 31 is then rotated on the screw 27 so that the shoulder 55 abuts against the recess stop 56, so that the contact rings are compressed between the conductor rings and the desired preload is achieved. Then the screw 27 'is inserted through the hole in the mounting flange 26 of the housing 21 and the hole in the adapter plate 24 and the screw 27 is slightly tightened. The rod 65 is then withdrawn, the tool still being held in place to ensure that the rod does not undesirably contact any of the contact rings as it is withdrawn. Finally, the tool 50 is carefully withdrawn without rotation so that the

809829/0844

open walls of the guide part 6] 5 do not have the contact rings touch un3 both visual screws 27, 27 'with the desired Torque tightened. The protective cap 4j5 is then on your Snap in place to seal the inside of the contact assembly from any foreign matter.

Although specific exemplary embodiments have been described in the above description, it is understood that other embodiments are also possible. For example, the adapter plate 24 can be omitted from the assembly process and associated apparatus, if desired, and the guide and stop devices formed by components 54, 56 and 57 can be formed directly as part of the bearing member. Furthermore, other guide and stop devices or arrangements can be used; for example the plate 24 with its recess 54 and stops 56, 57 can be omitted and a simple arrangement with a pin and an arcuate slot can be used. In this case, the pin can be fixed and extend through an arcuate slot in one of the flanges 26 in the bearing part l6, wherein the ends of the slot provide stops the pivotal movement of the ring housing Jl between the normal coaxial position and the eccentric or "charge "Position.

The preferred embodiment forms an electrical contact assembly that can operate under vibrational and shock conditions, the depth of the concave surface of the circular ring conductors being such that the power transmission contact ring is held and aligned by itself and maintains an electrical connection under these conditions without that frictional and clutch torques are exerted on the sensitive element due to the retaining mechanism for the contact ring. The current transmission element is self-aligning if any axial and / or angular misalignments of the conductor rings and / or the contact ring occur, this being done without the exertion of friction.

809829/0844 ./.

-JS-

and coupling torques on the sensitive instrument is achieved. Furthermore, there will be normal axial and radial misalignments of the two concave contact surfaces automatically compensated due to the fact that the radii of the two concave surface areas are less than half radial spacing and due to the fact that the smaller and larger axes of the loaded contact ring are approximately the same.

In the preferred method, the contact rings are placed in the shoulders of the concave surfaces of the inner and outer circular conductor rings without deformation, overstretching or Scratching of the contact rings built in, which is essential for a long reliable operation and a uniform and suitable clutch torque is achieved.

809829/0844

rs e it

Claims (13)

Patent Attorneys D-pl.-lng. Curt Wallach Dipl.-Ing. Günther Koch 2 8 0 1 9 6 fl Dipl.-Phys. Dr Tino Haibach Dipl.-Ing. Rainer Feldkamp D -8000 Munich 2 Kaufingerstraße 8 Telephone (0 89) 24 02 75 Telex 5 29 513 wakai d Date: Our reference: ig 126 - Fk / Ne Claims λ Electrical contact assembly for the transmission of electrical V, / energy between two components rotatable relative to each other about a common axis, thereby geke η η draws that first and second circular coplanar electrically conductive rings {~ 53, 38) are provided that one of these rings is arranged on one of the components (14, 16) while the other ring is rotatably arranged on the other of the components about the axis (1?) that the respective diameter of the rings (j53, jj8) has a relatively large radial gap (41) between form these rings and that at least one of the mutually facing surfaces of the rings (j53, 38) has a relatively flat arcuate concave shape in the direction of the gap, that an elastic wire-shaped, electrically conductive circular ring (42) with a free diameter greater than that Gap (41) is, and is provided with a generally flat outer surface that the circular ring in the gap (41) is compressed so that the circle ring (42) rolls on the or each concave ring surface essentially without friction during a relative rotation between the components (14, 16) and that the circular ring (42) in this way pretensioning forces between the flat circular ring surface and the or each concave ring surface with force components in such directions generated that the S09829 / 08U ORIGINAL INSPECTED Annular ring (42) within the or each concave upper r area is held. 2. Contact assembly according to claim 1, characterized in that both rings (33, 38) the relative have flat arcuate concave shape in the direction of the gap (41). 3. Contact assembly according to claim 1 or 2, characterized in that the components (14, 16) include inner and outer cylindrical parts (36, 31) made of insulating material with generally cylindrical outer and inner walls, that at least one of the cylindrical parts is relatively annular has flat arcuate concave surface (38 ^f or 33 ') on its wall, and that the corresponding conductive ring is formed by a thin metal film deposited on the concave surface of the wall. 4. Contact assembly according to one of the preceding claims, characterized in that the maximum free diameter of the circular ring (42) is such that when the circular ring is compressed in the gap (41), the circular ring surface contact with the ring surfaces is continuous, so that no clutch torques occur the components are exercised due to a bulging of the circular ring. 5. Contact assembly according to one of the preceding claims, characterized in that the or each concave ring surface has a predetermined radius of curvature and the width (W) of the outer surface of the Kr e Isring (42) is smaller than the width of the or each concave ring surface that the biasing force is force vectors generally parallel to the given radius at the points of contact between the flat outer surface of the 809829/0844 ^{# / #} Annular ring and the or each concave ring surface causes, and that the force vectors have unbalanced components when the circular ring (42) in the axial direction and / or angularly opposite the or each concave generally parallel to the axis of rotation Surface is misaligned and that the unbalanced components in the sense of holding the annulus in the or any concave surface. 6. Contact assembly according to one of the preceding claims, characterized in that the radius of curvature the concave shape of the rings has a predetermined relationship to the dimensions of the radial gap between the components. 7 · Contact assembly according to claim 3> characterized in that one of the cylindrical parts (31, 36) is fixed in the radial direction to one of the components (14, 16) with respect to the axis that fastening devices for movably attaching the other movable part to the other component between a normal coaxial Position with respect to the one component and an eccentric position with respect to the one component provided and that the size of this movement results in an enlarged radial gap which is larger than the free one Diameter of the annulus is so that the annulus can be used in the gap at the eccentric position can without it being bent and it is compressed in the normal position between the rings. 8. Contact assembly according to claim 7, characterized in that the fastening devices are adapter devices (24) between the outer cylindrical ring part (31) and the component (16), guide devices (53) on the adapter devices (24), which determine the normal position, and shoulder elements (55) on the outer cylindrical 809829/0844 * ^{/ #} include drical ring member (31) engageable with the guide means for movement of the component carrying the outer ring from the eccentric position to the normal position. 9. Contact assembly according to claim 8, characterized in that the guide devices (53) are formed by a channel (54) in the adapter devices to accommodate the component having the outer ring, that the channel (54) first stop parts (56) for arrangement of the cylindrical member (3I) of the inner cylindrical ring portion (36) and a second stop member (57) including the outer ring in the normal coaxial position with respect to the outer ring member (31) in the eccentric position with respect dee inner BauteiJs to hold, and that pivoting devices (? 6, 27) are arranged on the component of the outer ring in order to hold the component of the outer ring in the channel and to guide it between the first and second stop parts. 10. Contact assembly according to claim 9, characterized in that g e k e η η ze refuses that the outer cylindrical ring part has flange elements (26) extending therefrom in the radial direction extend, and that screw elements (27) are provided through the flange to this on the To hold component of an instrument, the pivoting devices also include screw elements. 11. A method of assembling the electrical contact assembly according to any one of claims 1 to 10, characterized by the steps of attaching the one of the rings (33 or 38) to one of the components (16 or 14) such that it is of a normal coaxial position with respect to the other ring can be moved into an eccentric position with respect to this component, so that a larger gap is formed on one side of the other ring which is larger than the free diameter of the circular ring, S0962Ö / 0ÖU · / · while a smaller gap is formed on the opposite side, the movement of one ring (33 or 38) in the eccentric position, the insertion of the circular ring (42) in the larger gap, the alignment of the annulus such that it is substantially coplanar with the inner and outer rings, and the movement of the one ring in the normal coaxial position such that the circular ring (42) between the inner and outer rings (33, 38) is compressed. 12. The method according to claim 11, characterized in that that the steps of inserting and aligning the circular ring on the arrangement of the circular ring (42) a rod (65) with a diameter that is smaller than the normal gap, the insertion of the rod (65) and the annulus (42) in the larger gap, aligning the annulus (42) with the inner and outer Include wrestling and removing the rod (65) after the rings are in their normal coaxial position are located. 13. The method according to claim 11 or 12, characterized in that g e k e η η ζ e i chne t that the contact assembly has a number of Includes ring and annulus assemblies that expose the axis are distributed that the rod is elongated and includes a corresponding number of grooves (67) in are distributed in a corresponding manner along its length, and that the method is the accumulation of a corresponding Number of circular rings (42) on the rod, the handle of the rod (65) such that a circular ring (42) in each the grooves (67) hangs, inserting the rod (65) into the larger gap and aligning the rod (65) such that each annulus (42) lies substantially in the plane of its respective rings. 80982Ö / 08U