A TRACK FOR EQUIPPING A VEHICLE
The technical field of the invention is that of tracks intended to equip a vehicle.
The tracks include, in a conventional way, a strip forming a closed loop, the strip including a running surface intended to come into contact with the ground and an inner surface intended to cooperate with at least one drive sprocket and at least one guide roller.
Conventional tracks consist of metal links articulated to each other and which can bear a shoe at the running surface.
So-called flexible tracks are also known, which are made of reinforced elastomer material, and which have the advantage of being light, silent and of allowing the vehicle to move at a higher speed.
All tracks, whether formed of links or made of elastomer, have the drawback of not decoupling the stresses associated with guidance and with the load, from the stresses associated with the contact with the ground.
The guiding and loading stresses are received mainly by the inner surface.
Loads associated with the contact with the ground are received by the running surface of the track.
A perturbation in the guiding of the track, which is caused by the contact with the ground, results therefrom.
The above causes excessive wear to the inner surface and to the teeth of the drive sprockets and can lead, in extreme cases, to untracking.
The goal of the invention is to propose a track which does not have such drawbacks.
Thereby, the track according to the invention makes it possible to decouple the function of driving by the motor of the vehicle and the function of connecting the track with the ground.
A reliable track drive, reducing wear and risk of untracking, results therefrom. A better road holding for the vehicle also results therefrom. Moreover, the track according to the invention makes it possible to limit the pressure on the ground.
U.S. patents US2011/301785 Al, US2010/282526 AL, US3934664 A, US2748827 A and US2746812 A disclose a track according to the preamble of claims 1 and 4. Thereby, the invention relates to a track intended to equip a vehicle, the track comprising a strip forming a closed loop, the strip comprising a running surface intended to come into contact with the ground and an inner surface intended to cooperate with at least one drive sprocket of the vehicle and at least one guide roller, in which track the strip comprises at least one first closed inner band that bears the inner surface and at least one second closed outer band that bears the running surface, the first band and the second band being arranged at a distance from one another and connected to one another by at least one linking means, the track being made from at least one elastomer material and the linking means being formed by slats, the track being characterised in that the slats comprise at least one metal] material embedded in elastomer and are locally overmolded with the first band and the second band. The slats can be evenly distributed along the strip. According to a particular embodiment, the track includes a first set of slats, or outer slats, distributed along the two lateral edges of the track and a second set of slats, or inner slats, arranged between the outer slats. The invention also relates to a track intended to equip a vehicle, the track comprising a strip forming a closed loop, the strip comprising a running surface intended to come into contact with the ground and an inner surface intended to cooperate with at least one drive sprocket of the vehicle and at least one guide roller, in which track the strip comprises at least one first closed inner band that bears the inner surface and at least one second closed outer band that bears the running surface, the first band and the second band being arranged at a distance from one another and connected to one another by at least one linking means, the linking means being formed by profiles comprising at least one elastomer material, the profiles extending transversely from one lateral] edge to the other lateral] edge of the track and being evenly distributed over the entire length of the track, the track being characterised in that the profiles comprise hollow hexagonal shapes connected to the band by arms.
The invention also relates to a track intended to equip a vehicle, the track comprising a strip forming a closed loop, the strip comprising a running surface intended to come into contact with the ground and an inner surface intended to cooperate with at least one drive sprocket of the vehicle and at least one guide roller, in which track the strip comprises at least one first closed inner band that bears the inner surface and at least one second closed outer band that bears the running surface, the first band and the second band being arranged at a distance from one another and connected to one another by at least one linking means, the linking means being formed by profiles comprising at least one elastomer material, the profiles extending transversely from one lateral edge to the other lateral edge of the track and being evenly distributed over the entire length of the track, the track being characterised in that the profiles comprise two sets of tongues, each set of tongues extending from one of the bands to a median slat, the tongues linked to the inner band being arranged alternating with the tongues linked to the outer band.
Advantageously, each band can comprise at least one ply of metal reinforcing cables.
The inner surface borne by the first band can comprise two lateral zones at which notches will be arranged which are intended to cooperate with teeth of the drive sprocket(s) of the vehicle.
The inner surface of the track can bear at least one guide block intended to cooperate with at least one slot borne by the sprocket(s) and the guide roller(s).
The inner surface of the track may bear at least one longitudinal tongue intended to cooperate with at least one groove carried by the sprocket(s) and the guide roller(s).
The invention will be better understood upon reading the detailed description thereafter of different embodiments, the description being made with reference to the enclosed drawings wherein:
— Figure 1 schematically shows a vehicle equipped with tracks according to the invention; — Figure 2a is a cross-sectional view of an embodiment of a track according to the invention, the cross-sectional view made along the plane, the trace AA of which is identified in Figure 1, and therefore at the sprocket;
- Figure 2b is a partial side view of the sprocket alone;
= Figure 2c is a partial sectional view of the track isolated from the sprocket, the track being cut by a plane, the trace BB of which is identified in Figure 2a;
= Figures 3a, 3b, 3c and 3d are partial side views of variants of embodiments of the track according to the invention.
Referring to Figure 1, a track-eguipped armored vehicle 1 includes a body 2 which is connected to the ground at each lateral] side of the body by at least one track 3. Such vehicle includes herein two tracks 3 which extend over substantially the entire length of the vehicle.
Fach track 3 is connected to propulsion means (such as a power train), not shown, by drive means.
The drive means rotate at least one drive sprocket 4 which cooperates with the track by teeth 17 which engage into notches 18 of the track 3
5 (see Figures 2b and 2c).
The track 3 is herein a flexible track which is made of at least one elastomer material, such as rubber, and the track includes a strip forming a closed loop.
The strip has a running surface 3a intended to come into contact with the ground and which can bear reliefs (not shown) facilitating its grip on the ground.
The belt also has an inner surface 3b which is intended to cooperate with the drive sprocket 4.
The track 3 is furthermore wound on a rear wheel 5 which also bears teeth 17.
Once installed on the vehicle, the track thus includes, in a conventional way, a lower link 7a which is in contact with the ground and onto which the vehicle 1 bears by means of the sprocket 4, the rear wheel 5 and guide rollers 6. Wheel 5, sprocket 4 and rollers 6 are connected to the body 2 of the vehicle by suspension means (not shown).
The sprocket 4, the rear wheel 5 and the guide rollers 6 further bear a median slot 22 which receives guide blocks 23 (Figures 2a and 2c) integral with the inner surface 3b of the track 3. To complete the guiding, the sprocket, the rear wheel and the guide rollers further bear circular grooves 24 (herein four grooves) which are arranged on both sides of the median slot 22 and which receive tongues 25 integral with the inner surface 3b of the track.
The tongues 25 form protuberances with smaller height than the height of the guide blocks 23. The tongues complete the guiding by increasing the relative contact surface between the inner band 9 and the sprocket, the wheel and the rollers.
The tongues complete the guiding provided by the guide blocks 23.
The track 3 further comprises an upper link 7b the movements of which are reduced in amplitude by tensioning rollers 8 connected to the body 2 of the vehicle. Figures 2a and 2c make it possible to specify the structure of the track according to the invention. The strip of the track 3 includes at least one first inner closed band 9 which bears the inner surface 3b and at least one second outer closed band 10 which bears the running surface 3a. Thereby, according to the invention, the first band 9 and the second band 10 are arranged at a distance from one another. They are connected to one another by at least one linking means 11. The distance between the first band 9 and the second band 10 is to be chosen depending upon the features of the vehicle to be equipped and the desired performance. The linking means consist herein of slats 11 comprising at least one metal material embedded in elastomer and which are locally overmolded with the first band 9 and the second band
10. Figure 2c schematically shows a plurality of slats 11 which are spaced apart from one another by empty zones 26. Each slat 11 includes a metal framework 27, which is schematically represented by dotted lines in the figure, and which extends from one band 9 to the other band 10. Said framework is embedded in elastomer material and hooks onto metal reinforcements 28 and 29 which are overmolded in the first band 9 and in the second band 10, respectively. Such a structure is similar to the structure of the carcass of a radial tire and the techniques for manufacturing such tires can be transposed to the production of the track according to the invention. According to the embodiment shown in Figures 2a and 2c, the track 3 includes two sets of slats:
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- a first set of slats called outer slats lla, which are distributed along the two lateral edges 3c and 3d of the track 3 (Figure 2a);
- a second set of slats called inner slats 1lb arranged between the outer slats lla (Figures 2a and 2c).
According to the configuration shown herein, the inner slats 1lb are connected to the first band 9 in the vicinity of the two lateral edges thereof and the slats are connected to the second band 10 in the vicinity of a median part 12 of the track 3, the part being situated at a median plane P of symmetry, perpendicular to the first band 9 and to the second band 10.
Thereby, according to the section of Figure 2a, the assembly of the inner slats lla and 1lb has substantially the general shape of the letter M.
As can be seen in Figure 1, the outer slats lla are also separated from one another by empty zones 26.
The structure of the outer slats 11 is identical to the structure of the inner slats lib.
These slats thus include a metal framework which extends from one band 9 to the other band 10. Said framework is embedded in elastomer material and hooks onto metal reinforcements 28 and 29 which are overmolded in the first band 9 and in the second band 10, respectively.
The slats 11 keep the two bands 9 and 10 at a distance from one another while imparting a certain flexibility to the connection.
The track 3 thus has a certain transverse flexibility permitting localized deformations of the outer band 10 caused by stones or obstacles situated on the ground.
Such deformations received by the outer band 10 are not transmitted to the inner band 9 and are absorbed by the slats 11 which form a carcass transverse to the track.
A driving comfort similar to the comfort which could be obtained with a wheeled vehicle, results therefrom.
Furthermore, the distance maintained between the bands 9 and 10 provides thermal insulation between the two bands.
Lesser heating of the track 3 results therefrom.
Finally, the track according to the invention can have (as represented in Figure 2a) an outer band 10 which is wider than the inner band 9. A reduction in ground pressure results therefrom, hence an improvement in the traction performance.
As can be seen in Figure 2a, each band 9 and 10 further includes a ply 13 of metal reinforcing cables 14. Such plies are conventional in the field of flexible tracks.
They serve to limit the elongation of the track 3 and improve the mechanical strength thereof.
It will be possible to provide one or a plurality of plies 13 on each band 9, 10, depending upon the desired performance.
It can be seen in Figures 2a and 2b that the sprocket 4 includes a median cylindrical part 15 which bears a disk 16 on each of the surfaces thereof.
The disks 16 bear (just like the rear wheel 5) peripheral teeth 17 which mesh in notches 18 which are arranged on lateral zones 20a and 20b of the inner surface 3b of the first band 9.
The guiding of the track is provided, as specified hereinabove, by the cooperation of the guide blocks 23 with the median slot 22, as well as by the cooperation of the circular grooves 24 with the tongues 25.
The drive of the track by the teeth 17 is thus carried out without excessive wear, the track being positioned laterally by the slot 22 and the grooves 24.
Figures 3a to 3d show other embodiments of the track according to the invention.
These embodiments all differ from the previous one in that the linking means between the bands 9 and 10 are not formed by longitudinal slats distributed along the perimeter of the two bands but consist of profiles 21 made of elastomer material which extend transversely from one lateral] edge 3c to the other lateral edge 3d of the track 3. Moreover, the profiles 21 are evenly distributed over the entire length of the track
3. The profiles 21 can have various shapes depending on the damping features desired for the connection between the two bands 9 and 10. Figure 3a thereby shows a track in which the profiles 21 have the form of transverse slats 21 which connect the inner band 9 and the outer band 10. During the motion of the vehicle 1, each slat 21 can crush and dampen the shocks. The slats 21 extend over the entire width of the track 3. The slats are made of the same elastomer material as the bands 9 and 10 and during the same injection manufacturing phase. The slats could (as in the previous embodiment) be provided with metal reinforcements which will hook onto metal reinforcements overmolded with the first band and the second band. Figure 3b shows a track 3 in which the profiles 21 comprise hollow hexagonal shapes 2la connected to the bands 9 and 10 by arms 21b. Such structure of the profiles provides greater rigidity. The rigidity can be adapted by varying the dimensions and the section of the hexagonal shapes. Figure 3c shows a track 3 in which the profiles 21 comprise two sets of tongues 2la and 21b which extend from one of the bands 9 or 10 to a median slat 21c. The tongues 2la linked to the inner band 9 are arranged alternating with the tongues 21b linked to the outer band 10. Such embodiment imparts the track 3 greater rigidity than the embodiment shown in Figure 3a. Finally, Figure 3d shows a track 3 in which the profiles 21 further include a median slat 21c and tongues 2la and 21b which connect the median slat 21c to the inner band 9 and to the outer band 10, respectively. Such embodiment differs from the previous one in that the tongues 2la and 21b are no longer perpendicular to the bands 9 and 10 but are arranged in an inclined way and thereby form triangles, the vertices of which are arranged alternately at the bands and at the median slat. Other shapes can be envisaged for producing the profiles
21. The profiles 21 can also be made of elastomer and obtained by simultaneous injection with the bands 9 and 10. The profiles could also be secured to a metal structure and overmolded with the bands 9 and 10. Additive manufacturing technologies could also be used. The invention has been described in embodiments for which the track has two closed bands of elastomer material (so- called flexible track). It is also possible to implement the invention with a metal track consisting of articulated links. In such case, e.g. an inner band will be made, consisting of articulated metal links and an outer band made of elastomer material will be attached around the inner band, connected to the inner band by linking means. The latter can comprise metal slats articulated on the links of the inner band and overmolded on metal reinforcements of the outer band. In any case, the architecture of the track according to the invention makes it possible to decouple the driving function which is provided by the inner band 9 and the function of connecting the track to the ground provided by the outer band 10.