Abstract:
Endless V-shaped belt, provided with longitudinal elements allowing the increase of the power transmitted with a conventional belt, comprises a rigid transverse part, integral with the longitudinal armature, used for the transmission of the motion by contact and pressure in the groove of a pulley, each transverse part being provided as a thin V-shaped plaquette (1), cut at the upper or lateral portion thereof to allow the passage and seating of the longitudinal armature.

Description:
This application is a continuation of application Ser. No. 539,610, filed 10/6/83, now abandoned, which is a continuation-in-part of application Ser. No. 217,003, filed 11/21/80, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to power transmissions of the &#34;belt&#34; or &#34;chain&#34; and grooved pulley type, allowing, for equal power, the space required therefor to be considerably reduced, so as to be applied more particularly to speed variators of this type. 
     As is known, very numerous types of variators exist in industry. All are heavy and cumbersome with respect to the power transmitted, which practically prohibits use thereof in vehicles. We find among them variators of the V-belt or chain and grooved pulley type. The belt variator is cumbersome because of the fragility of its textile belt. The chain variator, in addition to its less smooth operation, is also cumbersome because of the smallness of the surfaces in contact with the driven pulleys. 
     Other known variators are lighter and they use belts made of metallic strip-irons and with a direct metallic bearing-surface into the groove of the pulleys, of the type described in the German Patent Application published before Examination (Offenlegungsschrift) to HEYNAU No. 2 505 228 and in U.S. Pat. No. 3,949,621 to VARITRAC; those variators allow the transmission of more power than the belts having an elastomeric surface bearing on metal of the type described in the German Patent Application to VARITRAC No. 2 821 698 to which corresponds U.S. Pat. No. 4,213,350 to HOROWITZ; they, however, require a very high tensil stress and are very heavy; moreover, the strip-irons in contact with the transverse elements tend to wear and their manufacture is very complicated due to the necessity of using concentric strip-irons, without weld. 
     The belt according to the present invention in which the transverse elements are integral with an armature made of steel cable uses the principle of transmission metal on metal and a very strong armature able to take a high tensile stress, while eliminating the drawbacks of the belts made of strip-irons. 
     SUMMARY OF THE PRESENT INVENTION 
     The belt in accordance with the invention comprises a series of transverse plaquettes made either from a material increasing the friction, or from metal, for example treated wear-resistant steel or else from any other material, magnetic or not, able to provide the connection by friction. These plaquettes may be provided with a recess for receiving the cable or any other components capable of serving as a longitudinal armature (strip, braid, etc. . .). The plaquettes are solidly locked with each other and with the armature by means of an elastomer in which the assembly is embedded at the contact level of the armature and the plaquettes. The elastomer may be chosen so as to be oil-resistant (nitrile rubber, for example). 
     Besides the above arrangements, the invention comprises further arrangements which will become clear from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood with the help of the complement of description which follows, which refers to the accompanying drawings, in which: 
     FIG. 1 is a cross section of the belt, with an embodiment of the plaquette; 
     FIG. 2 is a longitudinal section of a part of the endless belt; 
     FIG. 3 is an elevational view of an embodiment having transverse rods; 
     FIG. 4 is a sectional view of the embodiment of FIG. 3; 
     FIG. 5 is a cross section of another embodiment of the plaquette, and 
     FIGS. 6a to 6d are embodiments of the toe of a plaquette. 
     It will of course be understood that these drawings and the corresponding descriptive parts are given solely by way of illustration of the subject of the invention of which they form in no manner a limitation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown, the belt comprises transverse plaquettes 1 having an external V shape, sufficiently cut-out at their upper part to receive, in the vicinity of the median plane perpendicular to the height of the trapezium, a single row composed of one or more cables 2 of metallic or similar fibers wound symmetrically with respect to the plane of symmetry of the belt, this arrangement, in the case of an even number of cables 2, avoiding the parasite deformations of the belt under traction. The cables 2 form the longitudinal armature of this endless belt. 
     Said armature rests directly into the cut-out part of the plaquettes 1. The winding of cable 2 must be the most even possible in order to avoid the parasite stresses during working of the belt. To this end, a machining of notches 5 (FIG. 5) having 1 to a few tenths of mm depth may be performed onto the surface 6 of the plaquettes 1, said notches 5 being used for positioning exactly cable 2. The cable path formed by the notches 5 has to be made helical according to the winding pitch of cable 2. Said winding pitch, which is of the order of one and a half diameter of the cable, must allow the presence of elastomer between two adjacent parts of the wound cable. Plaquettes 1 may comprise a toe 1a (see FIG. 6a) situated below the level of the cables, perpendicular to the surface of the trapezium and intended to distribute the pressure of the wound cable 2, at the moment when the plaquettes pass over the pulleys. The width of toe 1a is limited by the space between two successive plaquettes 1. This toe may have various shapes, namely: 
     shape 1a which has just been described, which is asymetrical and which is obtained by folding; 
     shape 1b (see FIG. 6b) made of two plaquettes 1 of half-depth each of which comprises a shape 1a, welded back to back. The advantage of such shape 1b lies in the symetry of the bearing of the longitudinal armature; 
     shape 1c (see FIG. 6c) to form 1b but obtained in one piece by forging plaquette 1; 
     shape 1d (see FIG. 6d) made of a rider inlaid onto plaquette 1. 
     In all cases, the total width of the plaquette must be smaller than the pitch of the concerned plaquettes. The sizes of the thicknesses of the plaquettes and of the spaces between the plaquettes are of the order of one to a few millimeters. The pitch of the plaquettes may be uneven in order to avoid resonance phenomena. Moreover, for the same purpose, the number of plaquettes may be chosen odd and preferably prime. An elastomer 3 joins the whole together by a known means, which consists in causing it to adhere strongly to the metal. The elastomer 3 does not run over laterally from the belt in order that the contact metal on metal with the grooves of the pulleys may be obtained. 
     According to an advantageous embodiment, the elastomer may be set back with respect to the plaquette 1, above and under the belt, in order to increase the flexibility. 
     For reasons of strength, the armature must be largely embedded (about two to three times the width of the cable). The shape of the set back for avoiding separation of the elastomer confers a festoon-look above the belt and an arch-look under it. 
     It is evident that the plaquettes described could also be cut-out or indented on both sides and then comprise a toe on each side, the introduction of the armatures being then effected laterally, or else be quite simply replaced by rods passing through the belt, so that their skew-shaped ends contact the internal faces of the grooves of the pulleys. 
     This latter embodiment is shown in FIGS. 3 and 4 which show that the rods 4, which may be circular, polygonal, and namely rectangular, in section, are in the same plane as the plaquettes 1 of FIGS. 1 and 2 which they replace. The armature cables 2 are supported on said rods 4. They could, finally, be replaced by any other pattern of rigid part solid with the movement of the armature of the belt, capable of transmitting the motion by contact with the grooves of the pulleys. 
     The armature instead of being formed of twisted metallic fiber cable strip, or braid, may be formed of a band of a few tenth of mm in depth, a width equal to the width of the bearing surface 6 of the plaquettes 1, and made of natural, synthetic or artificial woven fibers (such as &#34;Kevlar&#34; for instance). 
     The length of such a band might be such that when wound around itself, around the plaquettes 1, it might form an armature of about 1 to 2 mm in depth. In order to ensure a good penetration of the elastomer into the armature the band will have to be woven loose. 
     The belt, forming the subject matter of the invention, which may operate preferably in an oil bath, may be used anywhere where a power transmission is required, on a fixed machine or on a vehicle, whether it is a matter of a constant or variable ratio. It will preferably bear on V groove pulleys, made from an appropriate material: either an alloy increasing the friction or a treated wear-resistant metal. In order to increase the pressure of the belt in the groove of the pulley, the angle between the bearing faces of the belt may be reduced in comparison with that of a textile belt; it may be from 15° to 35°. 
     A particularly interesting application of this belt is represented by the equipment of variators which, because of the reduced space required therefor, may henceforth be advantageously fitted to motor vehicles in place of the gear boxes known up to present. 
     As is evident from what has gone before, the invention is in no wise limited to those of its embodiments and modes of application which have just been described more explicitly; it embraces, on the contrary, all variations which may occur to a technician skilled in the art, without departing from the scope or spirit of the present invention.