FR2966535A1 - Transmission joint i.e. cardan joint, for use in control device of aircraft, has bearings that permit relative rotational movement between covers and associated pivots, where bores of covers form track or sliding path for bearings - Google Patents

Abstract

The joint has a brace (50) that is equipped with four pivots (54). Two covers (24) are connected by the brace. Each of the covers is provided with a set of bores (34, 36) that are arranged longitudinally in a direction of opposing two pins of the brace. A set of bearings (60) permit relative rotational movement between each cover and associated pivots. Each bore of the cover forms a track or sliding path for the bearings. An independent claim is also included for a control device comprising a housing.

Description

The present invention relates to the field of universal transmission joints, conventionally called cardan joints, allowing in particular the transmission of a rotational movement between two concurrent non-aligned shafts. The present invention relates more particularly to a transmission joint of the type comprising a spider provided with four journals and two clevises each rotatably mounted on two opposite journals. A particularly interesting use of the invention relates to the mechanical transmission of the flight controls of an aircraft. Another interesting use of the invention may relate to the automotive field. In this field, patent US-B2-6,520,859 discloses a transmission joint comprising a spider with four journals, cups or sleeves mounted on the journals, and plain bearings each mounted radially between one of the journals and the associated socket so to allow a relative rotational movement between these two elements. The transmission joint also comprises two clevises each provided with two bores adapted to receive the sleeves mounted on two opposite journals of the spider.

The transmission joint described in this document has the major disadvantage of having a large number of parts to assemble and a large radial size. The present invention aims to remedy these disadvantages. More particularly, the present invention aims to provide a transmission joint having a limited number of parts, reduced radial size and low weight. The present invention also aims to provide an economic connection assembly, easy to manufacture and assemble. In one embodiment, the transmission joint comprises a spider provided with four pins, two yokes interconnected by said spider and each comprising two bores arranged longitudinally in the direction of two opposite journals of the spider for mounting said journals, and bearings each mounted on a journal to allow relative rotational movement between each yoke and the two associated journals. Each bore of the clevises forms a rolling or sliding track for the associated bearing. The use of each of the bores of the yokes to form a raceway or sliding for the associated bearing limits the number of parts to manufacture, store, handle and assemble to form the transmission joint. By providing direct contact between the bearings and the bores of the yokes, the intermediate mounting bushes used in the previous transmission joints are omitted. There is therefore a radially more compact transmission joint and reduced overall weight. In addition, the radial clearance between the spider and the yokes is more easily controllable. Moreover, the radial interposition of the bearings directly between the bores of the yokes and the trunnions makes it possible to increase the load capacity in the radial direction of the transmission joint.

Preferably, the transmission joint comprises rolling bearings provided with a plurality of rolling elements. In one embodiment, the bores of the yokes form cylindrical raceways. The rolling elements of the rolling bearings may comprise needles.

In one embodiment, the rolling bearings comprise a cage for maintaining the regular circumferential spacing of the rolling elements. Each rolling bearing may consist of rolling elements and the holding cage. Preferably, the cage is made in one piece, in particular by molding a synthetic material such as a polyamide loaded or not with mineral fibers. The cage can also be made in one piece of metal material, in particular from a sidewall of thin sheet by cutting and stamping.

Preferably, the yokes are made of steel. This makes it possible to obtain rolling or sliding tracks of satisfactory hardness without the need for a specific surface treatment.

In one embodiment, the spider comprises a central body and the journals made in one piece with said body. Alternatively, the pins are reported on the main body. Alternatively, the spider may comprise two shafts assembled one on the other and forming the trunnions.

In one embodiment, the transmission joint further comprises sealing caps each closing an axial end of one of the bores of the yokes. The invention also relates to an aircraft flight control device comprising a housing, a control lever movable relative to the housing, a transmission shaft connected to said lever and a transmission joint as defined above, in which one of the clevises is attached to the drive shaft and the other clevis is mounted on the housing. The present invention will be better understood on studying the detailed description of embodiments taken as non-limiting examples and illustrated by the appended drawings, in which: FIG. 1 is a schematic perspective view of a device FIGS. 2 to 4 are perspective views of a transmission joint of the device of FIG. 1; FIG. 5 is a sectional view of a connection assembly. FIG. of the transmission joint of FIGS. 2 to 4, FIG. 6 is a sectional view along the axis VI-VI of FIG. 4, and FIGS. 7 and 8 are perspective and sectional views, respectively. connecting link for transmission joint according to other embodiments. FIG. 1 is a diagrammatic illustration of an aircraft flight control device 10 comprising a control box 12 and a control lever 14 movable relative to the box about a roll axis 16 and a pitch axis. 18 to allow control of the rudder of the aircraft. The roll 16 and pitch 18 axes are perpendicular.

To ensure the mechanical transmission of the movement of the control lever 14, a transmission joint 20 illustrated in FIGS. 2 to 4 is mounted inside the housing 12. The transmission joint 20 comprises a first yoke 22 designed to be mounted on the control box, a second yoke 24 fixed to a transmission shaft (not shown) connected to the control lever and a linkage assembly 26 mounted between the yokes so as to enable the yoke 24 to be swiveled relative to the yoke 22. The yoke 24 comprises a tubular base 28 provided with a bore to allow mounting of the transmission shaft and two arms 30, 32 opposite extending from said base. Each arm 30, 32 comprises a cylindrical recess or bore 34, 36 arranged longitudinally along the roll axis 16. The yoke 22 comprises a cylindrical portion 40 enclosing inside which is mounted in part the yoke 24 and comprising two recesses or cylindrical bores 42, 44 extending along the pitch axis 18. At an upper axial end of the cylindrical portion 40 is provided a flat portion 46. As illustrated in Figure 5, the assembly 26 of connection comprises a cross 50 provided with a central body 52, of generally cubic shape, and four trunnion shafts 54, of axis 56, extending outwardly from said body being circumferentially spaced apart. The journals 54 are arranged in a single plane and at right angles to each other. An annular radial shoulder 58 is formed between each trunnion 54 and the central body 52. In the illustrated embodiment, the trunnions 56 are made in one piece with the central body 52. The assembly 26 of connection also comprises rolling bearings 60 mounted each on an outer cylindrical surface 62 of one of the pins 54 and identical to each other. Each rolling bearing 60 comprises rolling elements 64, constituted in the embodiment illustrated by a row of needles, and a cage 66 for holding. The outer cylindrical surface 62 of each trunnion 54 forms a cylindrical track or raceway for the rolling elements 64 of the associated rolling bearing. Each cage 66, of generally annular shape, comprises a plurality of windows 68 for housing the rolling elements 64 and their maintenance with a regular circumferential spacing. An axial end of the cage 66 is located axially in the vicinity of the shoulder 58 of the associated pin while remaining at a distance therefrom. The other axial end of the cage 66 remains axially recessed with respect to the end surface 54a of the associated pin 54. Each cage 66 is preferably made in one piece by molding a synthetic material having a low coefficient of friction. The cages 66 may for example be made of polyamide, filled or not with mineral fibers. Alternatively, the cages 66 may be made of metal material, for example from a thin sheet metal flank by cutting and stamping. In the illustrated embodiment, each set 26 of connection is constituted by the rolling elements 64 and the cage 66 holding.

As illustrated in FIG. 6, two rolling bearings 60 of the assembly 26 arranged on two opposite pins 54 of the spider are mounted directly inside the bores 34, 36 of the yoke 24 to mount the spider 50 on said clevis. The rolling bearings 60 are fully housed in the bores 34, 36 in the axial direction. The rolling bearings 60 remain axially recessed relative to the axial ends of the bores 34, 36. The bores 34, 36 each form a cylindrical track or raceway for the rolling elements 64 of the associated rolling bearing. The rolling elements 64 bear directly against the arms 30, 32 of the yoke 24 without the interposition of an intermediate mounting sleeve as is conventionally the case in the transmission joints of the prior art. This limits the number of parts forming the transmission joint by using the bores 34, 36 of the yoke 24 to form raceways for the rolling elements 64 of the rolling bearings 60. The radial size and the overall weight of the seal of transmission 20 are reduced. The bores 34, 36 of the yoke 24 are each centered on an outer cylindrical surface 69 of the central body 52 extending the large diameter edge of the shoulder 58 axially on the opposite side to the cylindrical surface 62. To limit the intrusion of At the level of the rolling bearings 60, each arm 30, 32 of the yoke 24 comprises a sealing cover 70 closing the axial end of the bore 34, 36 located axially opposite the cylindrical surface 69. exterior of the central body 52 of the spider. Each sealing cap 70 comprises a cylindrical sealing portion 72 which is housed in the bore 34, 36 associated and closed, at one axial end, by a bottom wall 74 situated axially in the vicinity of the end surface 54a. radial journal 54 of the spider while remaining at a distance from it. Each cover 70 also comprises a radial annular collar 76 extending the closure portion 72 axially opposite the bottom wall 74 and extending outwardly. The flange 76 bears against the outer surface of the arm 30, 32. The covers 70 are fixed on the yoke 24 by any appropriate means, for example by screwing, gluing, etc. The sealing caps 70 may be made in one piece by molding a synthetic material or metal material.

The two rolling bearings 60 of the assembly 26 left free by the yoke 24 are mounted inside the bores 42, 44 of the yoke 22 to obtain the mounting of the spider 50 on said yoke 22. The mounting of the two bearings to Bearing 60 in the bores 42, 44 is made identically to that previously described for the yoke 24. The bores 42, 44 each form a cylindrical raceway for the rolling elements 64 of the rolling bearing 60 associated. Sealing caps (not shown) are also mounted on the yoke 22, similarly to the yoke 24, so as to limit the intrusion of polluting particles at the rolling bearings 60. The yokes 22, 24 are advantageously made of steel so that the raceways formed by the bores 34, 36, 42, 44 have a satisfactory hardness to cooperate directly with the rolling elements 64 of the rolling bearings 60 without the need to provide a treatment specific surface area on said bores. In the embodiment previously described, the yokes 22, 24 are made in one piece. Alternatively, it is possible to make the clevises in two parts assembled against each other, for example by screwing, so as to form, after assembly, for each yoke two bores extending longitudinally in the direction of two journals 54 opposite of the spider 50 and forming cylindrical races for the rolling elements 64 of the rolling bearings 60. In an alternative embodiment, it is also possible, without departing from the scope of the present invention, to use sliding bearings or plain bearings as a replacement for rolling bearings.

In the embodiment previously described, the spider 50 of the assembly 26 of connection is made in one piece. In a variant, it is possible, as illustrated in FIG. 7, to provide a spider 80 provided with a central body 82 of generally cubic shape and comprising four tubular portions 84 extending outwardly from said body while being circumferentially equally spaced. The tubular portions 84 are disposed in a single plane and at right angles to each other. The spider 80 also comprises four shafts 86 fixed inside the tubular portions 84 of the central body 82 and projecting outwardly to form trunnions, of axis 88. The shafts 86 are fixed on the central body 82 by any suitable means, for example by gluing, crimping, fitting, welding, etc. As a variant, it is still possible to provide, as illustrated in FIG. 8, a spider 90 comprising two shafts 92, 94 assembled one on the other so as to form four journals 96, of axis 98, arranged in a only plane and at right angles to each other. The shaft 94 comprises a recess 100 passing through which is axially mounted on either side the shaft 92. The shafts 92, 94 can be assembled by any appropriate means, for example by gluing, fitting, welding, etc. Thanks to the invention, there is a transmission joint in which the number of parts to be manufactured, manipulated and assembled is reduced, more compact radially and in which the overall weight is decreased.

Claims (11)

REVENDICATIONS1. Transmission joint comprising a spider (50) provided with four pins (54), two yokes (24, 22) interconnected by said spider and each comprising two bores (34, 36, 42, 44) arranged longitudinally in the direction of two opposite journals of the spider for mounting said journals, and bearings (60) for allowing a relative rotational movement between each screed and the two associated journals, characterized in that each bore (34, 36, 42, 44) of the screeds forms a rolling or sliding track for the associated bearing (60). Transmission joint according to claim 1, comprising rolling bearings (60) provided with a plurality of rolling elements (64). Transmission joint according to claim 2, wherein the bores (34, 36, 42, 44) form cylindrical raceways, the rolling elements (64) comprising needles. 4. Transmission joint according to claim 2 or 3, wherein the rolling bearings (60) comprise a cage (66) for maintaining the regular circumferential spacing of the rolling elements. 5. Transmission joint according to claim 4, wherein each rolling bearing (60) consists of the rolling elements and the holding cage. 6. Transmission joint according to any one of the preceding claims, wherein the yokes (22, 24) are made of steel. 7. Transmission joint according to any one of the preceding claims, wherein the spider (50) comprises a central body (52) and the pins (54) made integral with said body. 8. Transmission joint according to any one of claims 1 to 6, wherein the spider comprises a main body and journals attached to said body. 9. Transmission joint according to any one of claims 1 to 6, wherein the spider comprises two shafts (92, 94) assembled on one another and forming the trunnions. 10. Transmission joint according to any one of the preceding claims, comprising sealing caps (70) each closing an axial end of one of the bores of the yokes. Aircraft flight control device comprising a housing (12), a lever (14) for movable control relative to the housing, a transmission shaft connected to said lever and a transmission joint (20) according to any of the preceding claims, wherein one of the yokes is attached to the transmission shaft and the other yoke is mounted on the housing.