JPS6261886B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to improvements in devices for transmitting electrical current between two relatively rotatable members within the class of slip-rings, and more particularly to improvements in devices for transmitting electrical current between two relatively rotatable members, generally included in the class of slip-rings, and more particularly, An improved apparatus for continuously transmitting current with substantially zero friction and coupling torque between a child member and a rotor member such as a relatively rotatable gimbal member of a gyro instrument. A current transmission device (electrical contact assembly) according to the invention comprises a specifically shaped contact surface of a radially spaced conductor ring located concentrically and in the same plane on two relatively rotatable members. An elastic fiber conductor loop is used which is compressed to a predetermined preload value in between. The conductor loop is self-captured on the contact surface and rolls over it during relative rotation when misalignment between the conductor rings or movement of the conductor loop occurs in a vibration-shock environment, causing the relative rotation to occur. A torque substantially equal to zero occurs between the two movable parts.

Rolling type electrical contact assemblies are generally not new and have been proposed in the past as an alternative to conventional slip ring-brush assemblies. Devices of this type are known, for example, in US Pat. No. 2,467,758 and US Pat.
Described in No. 3259727. To the applicant's knowledge, the devices disclosed in these US patents have not generally been put into practice by industry, particularly by manufacturers of precision sensing instruments such as gyro instruments.
The reason for this is probably that the form of contact assembly disclosed in these US patents was unsuitable for practical use in such applications.

As is well known to gyro engineers, slip rings and brushes supported by brush support blocks have long been used to transmit power and electrical signals across the relatively rotatable gimbal axes of gyro equipment. It was used. Although this system was satisfactory in terms of the main body, it was problematic in manufacture and use, and required frequent replacement of brushes or slip rings for repair and overhaul. Thus, the slip-spring-brush assembly is very delicate and requires a high degree of skill during installation and laborious adjustment work to achieve a preload or preload for minimal sliding friction under vibration-shock environments. and requires. Additionally, the assembly is typically exposed during repair or overhaul of the gyro instrument and is therefore susceptible to damage during handling. Gyro instruments, especially those installed on aircraft, operate in a vibrating environment and there is sliding friction between the brushes and slip rings, which can lead to the formation of frictional polymers that can cause shorts or opens, which can be time-consuming and labor-intensive. Very difficult removal operations are required for cleaning or replacement.
More importantly, in an autopilot system that derives the aircraft's airframe rate from a displacement gyro by differentiation of the gyro displacement signal, the characteristic noise of the slip spring brush assembly is amplified and the rate signal becomes undesirable noise. This means that it comes to include This requires high-altitude waves, which degrades the quality of the rate signal. Furthermore, conventional slip rings also generate harmful digital noise, for example in digital encoders. In addition, the slip spring-brush assembly, as is well known to gyro engineers, is relatively large due to the typically large number of slip springs and brushes required in modern electrically powered gyro equipment. Torque due to friction reduces the long-term accuracy of the gyro device.

With the above in mind, desirable properties for a contact assembly device that transfers electrical current between a relatively large number of relative pivoting members of a sensing instrument, such as two gimbal axes of a gyro device, are friction and coupling torque. virtually zero current, continuous current transfer even in shock-vibration environments, long service life, low manufacturing and assembly costs, and no vibratory sliding contacts. As a result, friction polymers are not generated.

The rolling type device disclosed in the above-mentioned US patent is
Although it may be suitable for some applications, it is inappropriate for sensing instruments where it is necessary to create a self-restraint or self-retention force between two relatively rotating members and to reduce friction and coupling torque. be.
Thus, U.S. Pat. No. 2,467,758 discloses a roller band conductor for use as a slip ring in an AC motor and as an electric switch potentiometer or variable resistor. 1 in any case
Because the two contact members are driven by a mechanical power source, in all applications intended or suggested by the assignee of U.S. Pat. It seems that this was not a design consideration. In applications such as sensing instruments, such as gyro instruments, friction due to electrical contact assemblies can cause undesirable torques on the supported members and therefore undesirable drift or preset, making it difficult to use the gyro as an accurate long-period reference. reduce the effectiveness of the device. Also, in that patent, the roller band is not self-captured or self-retained on the track path between both conductor rings, but requires a retaining flange or pin-pin hole type retaining device. Such flange and pin-pin hole type holding devices are often used because of their high frictional torque and variable coupling torque caused by the roller band coming into contact or sliding contact with the flange or pin-pin hole surface during rotation. It is unsuitable for this purpose. This variable large torque increases correspondingly when more circuits are involved, making the above-described retaining device completely unsuitable for low torque applications. Also, in that patent, the ratio of the free diameter of the loop to the radial distance between the inner and outer conductor members is quite large;
The loop distorts significantly when compressed into the radial gap, resulting in bond torque hysteresis and premature fatigue and failure of the metal material. Additionally, this distortion causes buckling and unbalanced torques. Significant distortion in the assembled loop makes it unsuitable for use in applications where substantially zero coupling torque is desired and required.

U.S. Pat. No. 3,259,727 discloses a current transfer device using flexible rolling elements with improved current transfer characteristics compared to U.S. Pat. No. 2,467,758. This improved transmission characteristic is achieved by giving the conductor ring on the relative rotating member a deep V-shape, so that the rolling contact elements wedge into the V-shaped recess, providing a wiping action and ensuring good electrical contact. This is achieved by U.S. Patent No. 3259727
The small diameter spring used in this issue closes on itself to form a torus. Since the diameter of the torus is very large compared to the radial distance between the V-shaped recesses, the assembled torus is highly distorted and engages in a wedge-like manner with the steep V-shaped wall; Creates a high torque connection. The flat band disclosed as an alternative embodiment also engages the V-shaped wall in a wedge-like manner similar to the torus. Therefore, the current transmission device described in this patent also has substantially zero friction and coupling torque due to substantial wiping or sliding friction as the rolling elements move into and out of the X-shaped recess. It is unsuitable for applications requiring a supported rotating member to be exerted by the device.

Thus, the above two U.S. patents do not propose a rolling contact assembly exhibiting low friction and coupling torque, but also disclose a method and apparatus for attaching a conductor loop in a radial gap between two conductor rings. It's not even a thing.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved electrical contact assembly for transmitting electrical power and/or electrical signals between a pair of coaxial and concentric relatively rotatable members, Substantially zero friction and coupling torque is provided by the electrical contact assembly to provide effective and reliable transmission of electrical energy. An electrical contact assembly according to the invention generally comprises an inner circular conductor having a relatively shallow concave conductive surface disposed coplanar with and concentric with the inner circular conductor, preferably having a similar concave conductive surface. an outer circular conductor having a conductive surface of . The relative diameters of the two circular conductors create a radial space or void therebetween. A fibrous conductor loop having a generally flat outer surface is disposed in the radial gap between the concave conductive surfaces of the circular conductor. The ratio of the free diameter of the conductor loop to the radial distance between the surface of the circular conductor and the thickness of the conductor loop, its elastic modulus and yield strength are such that the loop provides a given preload when installed in the air gap. , thereby maintaining a continuous redundant surface contact between the conductor loop and the concave conductive surface of the circular conductor.
The conductor loops also roll over the conductive surfaces of the circular conductors when assembled so that the conductor loops are self-locking with substantially zero friction and coupling torque as the circular conductors rotate relative to each other. The self-capturing action takes place by the inherent compensation of the bending moment occurring in each half of the conductor loop, independent of the magnitude of the preload, as long as the strain of the conductor loop does not exceed its yield strain.

Another object of the present invention is to operate in a shock or vibratory environment where the capture mechanism allows the conductor loop to self-capture to maintain electrical continuity without imparting friction and coupling torque to the sensing instrument. An object of the present invention is to provide an electrical contact assembly in which the depth of the concave conductive surface of a circular conductor is defined.

Yet another object of the present invention is to transfer current under conditions where there is angular or axial misalignment between the conductor loop and the conductor ring without imparting friction and coupling torque to the sensing instrument. The object of the present invention is to provide an electrical contact assembly in which the elements are self-aligned.

Yet another object of the invention is that the radius of the two concave conductive surfaces is less than half the radial gap and that the major and minor axes of the loaded conductor loop are approximately equal. It is therefore an object to provide an electrical contact assembly in which normal axial and radial misalignments of two conductive surfaces are automatically compensated for.

Yet another object of the present invention is to assemble conductor loops into the concave shoulders of inner and outer circular conductors without deforming, straining or damaging the conductor loops which is detrimental to service life and sustained bonding torque. An object of the present invention is to provide an assembly method and an apparatus for the same.

Next, the embodiment shown in the drawings will be explained in more detail.

Although the present invention is particularly useful in the sensing device shown schematically in FIG. 1A, it is equally useful in any other device in which low-torque electrical contact between relatively rotatable members is desired. Useful. 1st A
The detection device shown has a rotor case 12 which is supported in the rotor case 12 via a suitable spin bearing (not shown) for rotation at high speed about a normally vertical axis 13. The rotor case 12 is supported in a normally horizontal gimbal ring 14 for rotation about a first normally horizontal axis 15, and the gimbal ring 14 is mounted on a second horizontal axis perpendicular to the first horizontal axis 15. is rotatably supported in a stationary housing 16 about an axis 17 . As is well known, the rotor 11 rotates at high speed (spin motion),
When the bearings and conductive means supporting rotor case 12 and gimbal ring 14 exhibit zero torque coupling, the spin axis of rotor 11 holds its position indefinitely in space. Axes 15, 17 (gimbal axis)
are usually equipped with signal generators 18, 19, which generate signals proportional to the deflection of the housing 16 (eg, an aircraft) from the horizontal plane, which are used for aircraft control or display purposes. Rotor case 12
Since it is impossible to support the gimbal ring 14 without friction, in order to keep the rotor 11 upright with respect to the gravity reference, and for other purposes,
It is necessary to apply torque to the rotor case 2 and gimbal ring 14. This torque is Torca 20,
21. Usually rotor case 1
2 is supported for rotation about axes 15, 17 by precision ball bearings 22 (see FIG. 1). Modern gyroes are usually electric (i.e. rotor 12 is driven by an electric motor, signal generators 18, 19 and torquers 20, 21 are usually electric) and are therefore rotatable relative to housing 16. Means must be provided to transmit power and electrical signals between the gimbal ring 14 and between the gimbal ring 14 and the rotor case 12 which is rotatable relative to the gimbal ring 14 . Traditionally, this electrical energy transfer has been accomplished by a plurality of insulating slip rings mounted on a trunnion shaft extending from a bearing support structure and a plurality of corresponding brushes secured to brush support blocks secured to the bearing support structure. .
Each brush typically consists of a pair of very thin elastic wires carefully bent into pressure contact (i.e., frictional contact) with opposite sides of the slip ring. The large number of circuits normally associated with gyro operation requires a corresponding large number of slip rings and brushes, doubling the frictional torque. The spin axis of the gyro exhibits a well-known tendency to drift from its reference position at a rate substantially determined by the frictional torques present on axes 15, 17 (the gimbal axes). Precision ball bearings contribute to some extent to the drift speed of a freewheel, but the slip rings and brushes contribute the most. The quality of the gyro would be substantially improved if the coupling torque contributed by the electrical energy transfer device described above could be reduced to substantially zero. This is one objective of the invention. Also, because many gyroscopes are used for vehicle stability and control, they are affected by the vehicle's shock and vibration environment. In such environments, the brushes tend to slip on the surface of the slip ring, resulting in the formation of frictional polymers on the contact surfaces, which over time lift the brushes away from the slip ring, creating an open circuit condition. let In that case, it becomes necessary to take out the gyroscope and repair it, which increases the safety cost of the gyroscope.

Another object of the invention is to provide a current transmission device which does not have this frictional polymer problem. As mentioned above, brushes and slip rings are very delicate.
The initial installation requires maximum care, increasing manufacturing and security costs. Also, extreme care must be taken in handling the assembled equipment to avoid damaging the exposed delicate brushes. Yet another object of the present invention is to provide an electrical energy transmission device that is relatively easy to assemble, yet is completely protected and shielded.

In FIG. 1, which is an enlarged partial view of the gyroscope of FIG. 1A, the electrical energy transfer system associated with the support system between the gimbal ring 14 and the housing 16 is shown in cross-section. The housing 16 (fixed) of the gimbal ring 14 supports the gimbal ring 14 for rotation about an axis 17 in a precision ball bearing 22 via a trunnion 25 of the gimbal ring 14 . Trunnion 25 is hollow and provides passage for wires from the electrical contact assembly of the present invention. The extension 28 of the trunnion 5 provides a mounting structure for the inner circular conductor of the present invention along axis 17, which will be described below. A pair of tightening nuts 29, 29' are attached to the housing 16 and the extension 2.
8 and are used to tighten the ball bearings 22 in place.

Electrical contact assembly 30 according to the present invention serves to transfer electrical power or electrical signals between housing 16 and gimbal ring 14 with substantially zero friction and coupling torque applied to the gyroscope. Electrical contact assembly 30 generally includes an outer cylindrical housing 31, preferably of molded synthetic insulating material, having a mounting flange 26 secured to the outer end face of housing 16 by an adapter plate 24, described below, such as by screws 27, 27'. .
Shims may be added as necessary to properly align the conductor rings 33. A plurality of concave circular conductor rings (outer conductor rings) 33 are arranged along the inner surface of the housing 31 . Each outer conductor ring 33 may be a gold alloy commonly used in this type of application and is electrodeposited on the concave surface 33' of the housing 31, as shown in detail in FIG.
It is electrically connected by electroplating to a corresponding electrical terminal post 34 molded into the housing 31 to form an external circuit connection. An inner cylindrical member 36, also made of molded synthetic insulating material, is mounted within the extension 28 by, for example, epoxy cement. A plurality of corresponding concave circular conductor rings (inner conductor rings) 38 are evenly distributed along the outer surface 37 of the cylindrical member 36 .
Each inner conductor ring 38 is preferably a gold ring electrodeposited on a corresponding concave surface 38' of the cylindrical member 36, and the cylindrical conductor ring 38 is preferably a gold ring electrodeposited on a corresponding concave surface 38' of the cylindrical member 36 to provide a circuit connection with the electrical elements supported by the gimbal ring 14. It is electrically connected to a corresponding electrical terminal or lead 39 molded on member 36. Each inner conductor ring 38 is attached to the cylindrical member 3 in precise alignment with a corresponding outer conductor ring 33 of the housing 31.
6 and a plurality of conductor ring sets 3
3,38 are formed. All conductor ring sets 33, 38 are held concentrically and in the same plane within mechanical tolerances and, if necessary, by inserting shims between adapter plate 24 and housing 16. The relative diameters of the conductor ring sets 33 and 38, that is, the inner diameter of the housing inner surface 32 and the outer surface 37
The outer diameter of is selected such that a relatively large radial space or gap 41 is formed between them. to seal the electrical contact assembly 30 from dust and other contaminants to provide protection during handling;
A protective cover 43 made of synthetic material is fixed to the housing 31 in the form of a "hub cap" by elastic protrusions 44.
may be placed.

According to the invention, a plurality of corresponding continuous electrically conductive fibrous elastic loops 42 are arranged in the radial gap 41 . One conductor ring set 33, 38
One elastic conductor loop 42 is disposed for each of the rings, the generally flat outer surface of which contacts and rolls over the conductive concave surfaces of the concentric rings 33, 38. The terminal post 34 and the electric element on the gimbal ring 14 are electrically connected continuously by the conductor 39. Critical design parameters for the characteristics of the conductor ring surface and the conductor loop 42 will be described later, but the primary considerations governing the selection of such design parameters are:
Conductor loop 42 - minimizes the torque imparted on gimbal ring 14 by the interface of conductor rings 33, 38, and conductor loop 42 - in shock and vibration environments without contributing to excessive coupling torque.
To maximize the holding capacity between the conductor rings 33, 38 interface, to maximize the current carrying capacity of the conductor loop 42--conductor rings 33, 38 interface, and to maximize the reliability and life of the electrical contact assembly. .

As can be seen from the end view of FIG. 2, the conductor loops 42 of the electrical contact assembly 30 are typically randomly arranged within the radial gap 41 after a period of operation. The delicate conductor loop 42 and conductor rings 33, 38 are located inside the housing 31, as can be seen in FIGS. It is not exposed to the outside for contact.

The enlarged end view of FIG. 4 shows two conductor rings 42.
The state of the interface between the outer conductor ring 33 and the outer conductor ring 33 is illustrated. The two illustrated interfaces may be substantially the same. The concave surface of conductor ring 33 provides self-capturing and retention capabilities of conductor loop 42. The depth of the concave surface can be selected according to the severity of the shock and vibration environment of the gyroscope, as described below. Depending on the application, only one conductor ring 33 may be formed concave depending on the severity of the environment. After the concave surface 33' is formed by machining or otherwise to the desired radius and depth, the concave surface 33' is appropriately masked and a gold alloy is electrodeposited to the desired thickness (for example, 0.0000000032 mm). Terminal pillar 3
4 is molded into the housing 31 and exposed by machining of the concave surface 33' so that the gold alloy will also be deposited thereon and the external electrical connection of the conductor ring 33 will be formed. Alternatively, if desired, a separate copper ring may be molded into the synthetic material housing 31 to give the desired concave shape, and then nickel and gold or other suitable combination materials may be successively applied thereon. The concave conductor ring 33 may be formed by flash deposition. Conductor loop 42 may be gold plated as shown to improve the conductive properties of the electrical contact assembly.

The loop retention characteristics of the electrical contact assembly 30 according to the present invention allow it to be easily adapted to a wide range of vibration-shock environments without introducing distortion during assembly. By way of example, when a gyro meter incorporating an electrical contact assembly is operated in a mild environment, the depth of the concave surface 33' may be reduced as indicated by the dashed line shown as a small arc length in FIG. If the vibration-shock environment is severe, it may be necessary to increase the depth of the concave surface 33' and thus the length of the arc to prevent the loop 42 from falling off. However, it should be noted that in both cases the curvature is relatively shallow. The solid line represents a typical mild shock and vibration environment that can be expected in aircraft gyro applications. As an example, in the case of a gyro mounted on an aircraft, the radius of the concave surface 33' is
0.025″ (approx. 0.06mm), its depth is 0.19″ (approx. 4.8mm) in diameter
mm), thickness 0.02″ (approx. 0.5mm), preload 0.02lb (approx. 9
In the case of conductor loop 42 made of nickel alloy in g)
0.008″ (approximately 0.2mm), in which case 0.2g ² /Hz
None of the loops 42 fell off when subjected to random vibrations.

Although the electrical contact assembly 30 is often small in the sensing instruments described above, such as gyroscope instruments, in some applications the size of the electrical contact assembly 30 may be considerably large and the self-acquisition capability of the assembly may be ensured. It is desirable to do so. Therefore, conductor ring 3
The concave geometry of 3, the size of conductor loop 42, and the radial gap can be generalized as shown in FIG. 4A to suit various applications. Generally, the radius of curvature R _G of the recess 33' should be equal to or less than 1/2 the size of the radial gap 41.

That is, R _G ≦1/2 (R _O − R _I ) (1) where R _O is the outer conductor ring 33 defined below.
The radius of the point of contact between the inner conductor ring 38 and the conductor loop 42, R _I , is defined below
is the radius of the point of contact with

The sizes of R _O and R _I are as follows in the recess 33'
is a complex function of the radius of the conductor loop 42 and the width of the conductor loop 42.

R _O = R _IG + R _G [1-cos (tan ^-1 0.5w/R _G )] (2
) R _I = R _OG - R _G [1-cos (tan ^-1 0.5w/R _G )] (3
) where R _IG is the radius from the axis 17 to the bottom of the recess 38' for the inner conductor ring 38, and R _OG is the axis 17.
to the bottom of the outer conductor ring 33, W is the width of the conductor loop 42.

Furthermore, the axial restoring force, that is, the self-capturing force F _AR caused by the conductor loop-ring interface, is F _AR = (R _O - R _I /2R _G ) (if (R _O - R _I /2R _G )>1) 4) Next, regarding the design of the conductor loop 42, as mentioned above, the free diameter of the conductor loop 42 when incorporated into the radial gap 41 is the same as that of the conductor rings 33, 38.
The preload of the conductor loop 42 is determined by the ratio of its free diameter to the radial clearance. The value of this ratio is gimbal ring 14
The selection is such that during relative rotation between the conductor loop 42 and the conductor ring surfaces 16, a pure rolling contact between the conductor loop 42 and the conductor ring surfaces, and therefore a substantially frictionless contact between them, occurs. This criterion is as shown in FIG.
Select the characteristics of 2. In order for the surface of the conductor loop 42 to make point contact with the surfaces of the rings 33 and 38 as described later, the diameter of the conductor loop 42 should theoretically be exactly equal to the size of the radial gap 41 (see (See the asymptote in Figure 9). This is of course impractical, especially in shock-vibration environments. Therefore, a compromise between theoretical loop characteristics and actual loop characteristics is required, as will be described later. If the free diameter of the conductor loop 42 is made larger than the maximum limit, the conductor loop 42 will be significantly deformed when the conductor loop 42 is assembled between the conductor rings 33, 38, and as a result, the conductor loop surface will be No longer in even contact with the surface,
The middle conductor loop surface portion of the conductor loop ends undergoes buckling or lifts off the ring surface, and the ninth
Positive conductor loop contact occurs at four locations along the conductor loop plane, as shown in the top diagram of the figure. Geometrically, this means that there is no true rolling contact between the conductor loop 42 and the conductor rings 33, 38;
This means that friction torque is generated due to slippage at the interface. This "jinzo" or "jelly bean" shape imposes excessive strain on the conductor loop 42, causing material fatigue and failure of the conductor loop 42 after a relatively small number of revolutions, allowing for an acceptable service life. Make it as short as possible. What is even more important is that the conductor loop 42 will not bulge after assembly.
The shape or "jelly bean" shape creates uncompensated bending moments in the conductor loop 42 during rotation of the rotating member, increasing coupling torque. This is the conductor loop 4 around the air gap 41.
It can be called the torque sensitivity to the angular position of 2.

In many applications of the invention, particularly those with gyro instruments, perfect continuous concentricity between the conductor rings 33, 38 is dependent on the characteristics of the ball bearing 22, machine cutting tolerances, compliance caused by the environment of the instrument, etc. Therefore, it cannot be realized. The diameter of the conductor loop 42 is therefore selected such that the desired preload for such misalignment conditions is provided at the maximum eccentric air gap location. This means that at the position of the minimum eccentric air gap the preload of the conductor loop 42 will be greater than the desired value. If the free diameter of the conductor loop 42 is too large, the radii at its ends will be unequal and the conductor loop 42 will create a coupling torque on the rotating member. This is illustrated in the top diagram of FIG. 9 by the dashed position of the "jinzo" shaped conductor loop 42. Therefore, the preferred conductor loop 42
The free diameter of the conductor loop 42 is also maintained during operation when the conductor rings 33, 38 are no longer exactly concentric.
This value is such that the radii at both ends of the radius are approximately equal.

To obtain the desired conductor loop-to-conductor ring contact preload without buckling, many correlated conductor loop parameters must be considered. Generally, the radial size (R _O -R _I ) of air gap 41 and the axial width W of conductor loop 42 are determined by the desired basic design size of contact assembly 30. As an example, the size of the radial gap 41 is approximately 0.2″ (approximately 5.1
mm, and the axial width W is approximately 0.02″ (approximately 0.51 mm).
Second, the loop material is selected. This selection depends on several factors, including resistance to deformation (which requires the material to have a high elastic modulus) or the ability to deform without breaking (which requires the material to have a high yield strain). This will be done based on the requirements of An example of a suitable material is a 95% nickel alloy with a modulus of elasticity of 30 x 10 ⁶ and a yield strain of 200,000 psi (about 14,000 Kg/cm ² ). This alloy is sold by Metsuku Metals of California, USA. Assuming that each of the above parameters is constant, the remaining parameters to be determined are Y _T when installed in the cavity 41.
The free radius R _F and the radial thickness t of the conductor loop 42 should produce the desired conductor loop-conductor ring preload F _N when deflected by .

It should be noted here that a wide range of parameter selections are possible in the assembly method and apparatus of the present invention in order to meet a correspondingly wide range of recycling requirements. As an example, without the assembly method of the present invention, the maximum free diameter and loop material and thickness of the conductor loop 42 and the conductor ring 3
The depth of the recesses 33', 38' for 3, 38 is limited by the amount of deformation of the conductor loop 42 when inserted into the radial gap 41 between the conductor rings 33, 38. In accordance with the present invention, the design parameters of most of the conductor loops 42 and recesses 33' are not limited by mechanical assembly considerations or constraints.

The preload amount F _N expressed in pounds lb is obtained by the following approximate formula.

F _N = Y _T EW _F (t/R _F ) ³ (5) where Y _T is the deflection of the conductor loop 42, E is the elastic modulus of the link material, W _F is the width of the conductor loop 42,
t is the thickness of the conductor loop 42, R _F is the thickness of the conductor loop 4
The free radius is 2.

FIG. 9 is a diagram showing the relationship between the thickness t of the conductor loop 42 and the free radius R _F for a family of curves with a constant preload F _N . In FIG. 9, the elastic modulus of the conductor loop 42 is constant at 0.51 mm, and (R _O - R _I ) is approximately 3.8.
mm, the elastic modulus of the conductor loop 42 is 30×10 ⁶ , and the yield strain is 14000 Kg/cm ² . Obviously, the maximum preload depends on the size of the conductor loop 42 and the conductor ring 3.
3.38, the desired maximum preload occurs for a free radius of conductor loop 42 equal to approximately 2.9 mm. Also, a free radius of the conductor loop 42 larger than the radius at _the desired maximum preload will result in undesirable contact characteristics, i.e. _buckling ; It should be noted that the radius provides the desired contact characteristics, ie pure rolling contact.
Therefore, basic design considerations determine any desired preload F _N once the parameters (R _O -R _I ) and W are determined. For example, at point A in Figure 9, the loop thickness is approximately 0.023 mm, and the preload is 0.02 lls.
(approximately 9 g), the free radius of the conductor loop 42 must be 0.096'' (approximately 2.4 mm).
When the preload is 0.03lls. (approx. 13.5g), the free radius remains the same and the thickness is approximately 0.0013″ (approximately 0.03
mm). Two free radii (A in Figure 9,
B), but one value B is too large and causes undesirable buckling when attached to the air gap 41. It is generally advantageous to keep the excursion of the conductor loop 42 at a small value by selecting the above-mentioned thickness such that an optimum loop bending moment compensation is maintained which minimizes the torque sensitivity to changes in the radial gap 41. It is.

The self-acquisition and retention capabilities of the rolling conductor loop assembly will now be described with reference to FIGS. 5-8, noting the shape of recess 33' in FIG. 4A. Self-capturing capability is achieved without the use of V-grooves or vertical guide walls on each side of conductor rings 33, 38 as shown. This is because, in actual operation, this type of wall creates substantial coupling torques. In accordance with the present invention, a relatively shallow concave groove or recess formed in at least one of the relatively rotatable members cooperates with the generally flat outer surface of the conductor loop 42 to move the conductor loop 42 into the recess 33'. , 38' (due to preload)
Generates a force vector. Since these forces occur during rolling contact, they do not contribute significantly to the coupling torque between both rotating members. Such self-retaining action of conductor ring 42 is particularly advantageous when the recesses of one rotating member are not precisely aligned or coplanar with the recesses of the other rotating member, reducing manufacturing costs. (A simple system can be used to obtain alignment with sufficient precision as described above). The above-mentioned restoring force also causes the conductor loop 42 to move into the recesses 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33', 33' and 330'.
Self-retained in 8'.

5-8 illustrate three typical cases of misalignment or disturbance of the conductor loops 42 relative to the conductor rings 33, 38. FIG. 5 illustrates the lateral or axial displacement of the conductor loop 42 (possibly due to a slow turn of the aircraft). Under this condition, the force vector produced by the preload force F _N includes a lateral or axial component that creates a restoring force and tends to return the conductor loop 42 to a force equilibrium position. FIG. 6 illustrates axial misalignment of conductor loops 42 (eg, due to deviation of inner conductor ring 33 and outer conductor ring 38 from the same vertical plane). Again, as can be seen from the analysis of the force vectors, no moment is created which tends to rotate the conductor loop 42, but rather an axial force which tends to hold the conductor loop 42 in the recesses of the inner and outer conductor rings. A resultant force component is generated. 7 and 8, as a result of the kinked misalignment (represented by angle θ) of the conductor loop 42 with respect to the concave surface of the conductor ring, the edges of the outer peripheral surface of the conductor loop 42, which has a generally rectangular cross-sectional shape, is shown contacting the concave surface of , thereby generating a restoring moment M. Figure 7 shows the conductor loop 42.
is angularly translated (rotated or twisted by an angle θ) about the radial line of electrical contact assembly 30; FIG. The figure shows a case where the object is angularly translated (rotated by an angle θ, that is, twisted) away from the normal plane.

What should be noted here is that whether the rectangular or V-shaped recess is deep or shallow, the conductor rings 33, 3
The point is that the above-mentioned self-trapping force does not occur when the elements 8 are misaligned. Such axial misalignment may occur during operation of the gyro instrument in the presence of gravity during flight. In the case of a rectangular recess, the conductor loop 42 merely abuts against the side wall of the recess, distorting the conductor loop 42 and generating a high frictional torque, so that no restoring force is generated. Similarly, even if it is shallow, V
In the case of a letter-shaped recess, the axial misalignment of the conductor rings 33, 38 actually produces divergent forces. This force tends to move the conductor loop 42 out of the recess 33' without returning it into the recess 33'.

Another feature of the invention is that the recess 33' and the conductor loop 4
In combination with the flat outer surface of 2, ample conductor loop contact points are obtained, thereby forming a continuous electrical connection.

In accordance with the teachings of the present invention, the rolling conductor loop assembly is constructed such that the delicate conductor loop 42 is free from deformation, undue strain, or damage of any kind within the annular air gap between the inner conductor ring 38 and the outer conductor ring 33. It is designed to be assembled in 41. It is very important that the conductor loop 42 is not damaged for the following reasons. That is, if the conductor loop 42 is even slightly scratched when handled with tweezers or otherwise, it will not only cause a torque change, but will also be susceptible to breakage from that point after a short operating time. Furthermore, without the assembly method and apparatus of the present invention, conductor loop 42 would have to be deformed using some sort of expansion tool in order to insert conductor loop 42 into cavity 41. Therefore, the expanding tool itself may damage the conductor loop 42. Furthermore, when such a tool is used, the void 41
The conductor rings 33, 38 are guided through the conductor loops.
(This is a very tedious and time-consuming task) and requires skilled personnel. The assembly method and apparatus of the present invention solves all of these assembly problems and can be accomplished by unskilled workers in a very short time as described below. Furthermore, the assembly method and apparatus according to the invention provides various free diameters in the recesses 38', 33' of the inner conductor ring 38 and the outer conductor ring 33 with depths that vary according to the severity of the shock and vibration environment of the gyroscope. Alternatively, it is possible to install a conductor loop assembly with a preload.

The assembly method and apparatus of the present invention are described in the second, 2A,
3 and FIG. 3A will be explained. The assembly device of the invention basically includes an adapter plate 24 and an assembly tool or fixture 50 (see Figures 3 and 3A). Adapter plate 24 and screws 2 as described above.
7, 27' can be adapted to the housing 31 and the housing 16. Multiple adapter plates 24 may be designed for different gyro instrument configurations. The adapter plate 24 is generally circular;
Gyro housing bearing - has an inner annular projection 51 that ultimately positions and concentrically aligns the conductor assembly relative to the trunnion opening 52. The outer surface 53 of the adapter plate 24 is connected to the inner shoulder 55 of the housing 31.
It has an outer recess 54 for receiving (see FIG. 1). An inner shoulder 55 extends from below the mounting flange 26 to the depth of the outer recess 54. The outer recess 54 has an annular projection 51 and a first substantially semicircular stop surface 56 (second A,
3), thereby limiting the normal concentric assembly position of the housing 31 with respect to the inner conductor ring 38. A flat outer recess 54 extends beyond the normal position of the housing 31 on the side opposite the stop surface 56 and
forming a second radially offset substantially semicircular stop surface or stop portion 57 concentric with the outer circumferential surface of the stopper. This limits the eccentric position of the housing 31 with respect to the inner conductor ring 38. The overall shape of the outer recess 54 is similar to that of the housing 3.
1 is pivoted about one of the screws 27, 27, for example screw 27, from a normal or closed position concentric with respect to the inner conductor ring 38 to an open or "loaded" position eccentric to the inner conductor ring 38. make it possible to Thus, in the "loaded" or open position, a relatively large radial space is formed between each side of the inner conductor ring 38 and the outer conductor ring 33 of the contact assembly. This relatively large radial spacing allows for the assembly of conductor loops 42 of different diameters. In fact, that space allows assembly of conductor loops 42 of a diameter that provides maximum preload (without buckling, as discussed above).

Alternatively, instead of pivoting the housing 31 about its one screw 27 or 27' as shown in FIGS. 2, 2A and 3, the outer recess 54 of the adapter plate 24 can be connected to the trunnion 25 and the inner conductor. 10 and 10A with respect to the ring 38, and the extension 31' of the housing 31.
is fitted into the recess 54 and located correspondingly eccentrically with respect to the inner axis of symmetry of the housing 31;
The inner axis of symmetry may be aligned with the axis of the inner conductor ring 38 in the normal position of the housing 31. In that case, the mounting screws 27, 27'
Rotating adapter plate 24 prior to insertion moves housing 31 eccentrically to create an enlarged radial space for mounting conductor loop 42, as shown in FIG. 10A.

The fixture 50 of the assembly apparatus shown in FIGS. 2, 3, and 3A allows the conductor loop 42 to be removed easily without the need for a tool such as tweezers that can easily damage the conductor loop 42.
2 can be quickly assembled. Fitting 50 is preferably molded from a suitable synthetic material. Fitting 50 includes a circular flange-like base portion 60 having a diameter larger than and bridging the inner diameter of housing 31 so that the axial surface of housing 31 serves as an alignment stop for fitting 50 in use. have The fixture 50 has a base portion 60
It can be easily operated by an extension 61 and a knob 62 on one side. A hollow cylindrical or guide portion 63 is formed to extend from the center of the other side of the base portion 60. Guide portion 63 has an inner diameter that is a slip fit over inner conductor member 36 and preferably a length sufficient to extend beyond the innermost inner conductor ring 38 of cylindrical member 36 .
The guide portion 63 is cut out on the side opposite the enlarged gap 41, as shown at 64 in FIG. 2A, so that the conductor loop 42 can be engaged with the inner conductor ring 38 as described below.
Laterally displaced from the guide part 63, a rod 65, preferably made of synthetic material, is slid into a mounting hole 66 of the extension part 61, opposite the cutout part of the guide part 63. The rod 65 has a thickness or diameter that is substantially smaller than the size of the normal gap 41, and has a plurality of recesses 67 formed at one end at intervals corresponding to the spacing of the conductor rings 38, and an appropriate recess 67 at the other end. A knob 68 is formed. A suitable low spring pressure ball detent device 69 is provided for positive rod positioning during use. However, using only Rod 65,
The operator may manually guide the rod 65 into the enlarged cavity 41.

During operation, the operator, preferably in a clean room, unrolls several conductor loops 42 from the container onto a soft, lint-free surface such as sponge rubber or sponge plastic, and then extends the rod 65 in the extended detent position ( This causes a dent 67
Pick up at least the number of conductor rings 42 that should be inserted into the ends of the rods 65 (which are aligned with the conductor ring pairs during assembly), manipulate the fixture 50 by hand, etc., and place them in each recess 67. 1 conductor loop 4
2 can be positioned freely. Next, with the axis of the conductor member 36 in a horizontal position, the tip of the guide portion 63 is positioned on the outer end of the inner conductor member 36, and the arrow or marker 70 on the adapter plate 24 is aligned with the arrow or marker on the base portion 60. Rotate it so that it is aligned at 71. This ensures that the rod 65 is properly aligned within the enlarged radial gap 41. The fixture 50 is then advanced until the inner surface of the base portion 60 abuts the outer surface of the housing 31. This aligns all conductor loops 42 in the same plane with the corresponding inner and outer conductor rings 33,38. The operator then rotates the housing 31 about the screw 27 to compress the conductor loop 42 between the conductor rings 33, 38 and create the set preload. The screws 27' are then inserted into the holes in the mounting flange 26 of the housing 31 and the adapter plate 24, and the screws 27' are preferably lightly tightened. The operator then withdraws the rod 65 while leaving the fixture 50 in the assembled position so that the rod 65 will not inadvertently come into contact with the conductor loop 42 during removal. Finally, the fitting 50 is carefully removed without rotation so that the open wall of the guide part 63 does not come into contact with the conductor loop 42, and the screws 27, 27' are tightened to the desired torque value. A protective cap 43 is snapped into place to protect the interior of contact assembly 30 from foreign objects.

The embodiments described above are illustrative, and other embodiments are possible within the scope of the present invention. For example, in the assembly device described above, the adapter plate 24 may be omitted if desired, and the outer recess 54 and stop surfaces 56, 57 formed directly on the support member or housing 16.
Furthermore, other guiding or stopping means may be used. As an example, the adapter plate 24, along with the outer recess 54 and stop surfaces 56, 57, can be omitted and a simple pin-arc slot combination used. In this case, the pin is secured to the housing 16 and extends through an arcuate slot in one of the mounting flanges 26, the ends of which allow for a normal coaxial position and an eccentric position, the "load" position. A stop portion is formed to limit the rotation of the housing 31 between the housings 31 and 31.

Although the present invention has been described with reference to preferred embodiments, the present invention can be modified in many other ways, and the embodiments described above are merely illustrative and do not limit the present invention.

[Brief explanation of the drawing]

FIG. 1 shows the contact assembly of the present invention incorporated into one gimbal shaft of a gyroscope, and line 1 in FIG.
1A is a schematic plan view of a typical gyro device; FIG. 2 is an end view of the contact assembly of FIG. 1 with the protective cover removed; FIG.
Figure A is an end view of the contact assembly ready for attachment of the conductor loop; Figure 3 shows the arrangement for attaching the conductor loop between the conductor rings; line 3-- of Figure 2A;
4 is an enlarged view of the conductor loop-conductor ring interface; FIG. 4A is an explanatory diagram showing the general geometrical shape of the conductor loop-conductor ring interface;
5-8 are explanatory diagrams representing the force vectors and moments that cause conductor loops to self-align and self-capture; FIGS. 9 and 9A are diagrams useful in understanding the principles of the invention; FIGS. FIG. 10A is a partial side cross-sectional view showing the attachment of a conductor loop according to another embodiment. In the figure, 14 is a gimbal ring (rotating member), 16
is a housing, 17 is an axis, 30 is a contact assembly,
33, 38 are conductor rings (rings), 33', 3
8' is a concave surface, 41 is a radial gap, and 42 is a conductor loop.

Claims (1)

[Scope of Claims] 1. An electrical contact assembly for transmitting electrical energy between a first member and a second member that are relatively rotatable about a common axis, comprising: (a) about the axis; (b) first and second circular conductive rings located in the same plane, respectively disposed on the first member and the second member so as to rotate relative to each other; (b) the first ring; and the second ring define an air gap therebetween having a relatively large predetermined radial width, and the first ring and the second ring have relatively shallow arcuate concave surfaces facing each other. (c) an elastic fibrous electrically conductive circular loop consisting of an annulus having a generally rectangular cross-sectional shape and a free diameter greater than the radial width of the void; the loop is compressed in the void;
Thereby, the two mutually spaced edges of the outer peripheral surface of the loop prevent the axial and radial deviations between the first ring and the second ring that occur during relative rotation of the first member and the second member. The loop is capable of contacting the arcuate concave surface of the ring along a line of contact that varies depending on alignment and angular misalignment, and the size of the free diameter is such that the loop The compressed loops are configured to roll substantially frictionlessly along the line of contact during movement, and the compressed loops are configured to roll along the line of contact substantially frictionally, and the compressed loops are configured to roll substantially frictionally along the line of contact, even in the presence of the misalignment. and the arcuate concave surface of the ring to create a preload force having a force component in a direction to retain the loop within the arcuate concave surface.