FR3052430A3 - CROSS-ASSIST DEVICE - Google Patents

Abstract

The principle of the present invention is to provide a vehicle with a device allowing it to overcome obstacles too high for its wheels to allow it to cross easily. The vehicle comprises a first running gear like one or more wheels, but a second running gear is located next to the wheel 1 and connected to its support by a mechanical connection of known type. In its rest position, the second undercarriage is arranged so that it does not touch the ground and meets an obstacle first, before the wheel 1. This has the effect of moving it backwards. It then gradually lifts the vehicle until the wheel 1 can roll on the top of the obstacle. In an improved version the second undercarriage is connected to the frame by a cradle 60 which can pivot about an axis parallel to the axis of rotation of the wheel 1 when it encounters an obstacle.

Description

Crossing assistance device

Technical area

The present invention is a device that improves the crossing capacity of vehicles. Prior art

The main factor that determines the crossing capacity of a vehicle is the diameter of its wheels. The larger the diameter, the higher the vehicle can cross over obstacles. Several devices have been devised to allow vehicles to cross larger obstacles without increasing the diameter of their wheels, including those described in the two following documents: - US2002104692Al (Eiji Nakatsukasa and Al. [JP] - 2002 08 08) which discloses a vehicle comprising said laterally offset pivoting arm whose distal end can be positioned on the ground to lift the vehicle. - US8764027B1 (Délia Polla Michael [US] - 2014 07 01) which describes a foot pivotally attached to the front portion of a carriage, allowing the vehicle to be rotated around the end of this foot to assist a user to take a step up stairs. - EP0740542 (B) (Degonda & Wuethrich [CH] + 1995 11 17) which discloses a wheelchair comprising a front wheel and a steerable rear wheel and an energy storage means assisting the passage of obstacles

We also know the big idler roller serving as a fulcrum to cross the rough terrain that fitted the Citroën inset of the Yellow Cruise in 1931.

Problem

Increasing the size of the wheels increases the size and cost of a vehicle, whereas this increase only affects the crossing capacity when the vehicle encounters an obstacle. Apart from this rare case, when the vehicle is traveling on flat ground, a smaller diameter wheel would do the trick.

It is true that increasing the diameter of the wheels also results in improved comfort, but this problem can be solved by a good suspension, all the more easily as we now know how to build so-called active suspensions, which make automatically vary the height of the vehicle relative to the ground according to the profile of the road as it has been analyzed in real time by sensors of different types.

Presentation of the invention

The present invention is a crossing aid device for a vehicle comprising - a chassis 2, - a first running gear comprising one or more elements such as for example a wheel having a contact surface with the so-called ground-primary contact surface 1 permanently supporting it when it is on flat ground, - and a second undercarriage comprising an assembly 3 of one or more contact surfaces with the so-called ground-secondary contact 3 - such as crawler rollers or a pad forming a wheel portion -, said second undercarriage being connected directly or indirectly to the frame 2 of the vehicle by a mechanical connection 4, characterized in that: - said mechanical connection 4 guides an element of said contact-ground-secondary 3 to when it is pushed backwards, from a so-called rest position in which - the front part of the assembly 3 of said secondary-secondary contact (s), as the case may be, is located above and in front of the lowest point of said primary-ground contact 1 of the vehicle, - the vehicle rests on the ground by said first undercarriage, - no part of said ground-secondary-contact 3 touches the ground, towards a so-called working position in which the vehicle rests on said second undercarriage, - that no part of said ground-secondary contact 3 is in contact with the ground when the vehicle is placed by its contact-ground-primary 1 on horizontal flat ground, that said second undercarriage is provided with a return means at its rest position when it is not in contact with the ground, and that the whole of said one or more ground contacts; secondary case is shifted laterally relative to said contact-ground-primary 1, and a sufficient lateral distance thereof to not be able to get caught between said contact-ground-primary 1 and the ground. it being specified that above and hereinafter by obstacle is meant any part of the ground higher than that on which said first rolling element rests when said second running gear is in the rest position.

According to other features, an element of said second undercarriage is driven in motion either by an independent motor or by mechanical cooperation with an element of said first undercarriage; in the so-called rest position, no part of the ground-secondary contact 3 is driven in motion by a motor or by mechanical cooperation with an element of said first undercarriage; the passage of said second running gear in working position brings into contact a cooperation element 13 of said first running gear with a cooperation element 33 of said second running gear; after having passed through the so-called working position, said second undercarriage reaches a so-called retracted position in which the lowest part of said ground-secondary contact 3 is higher than the lowest part of said ground-primary contact 1 and therefore does not touch the ground; the second undercarriage is connected to said chassis 2 by means of a cradle 60 which can rotate about an axis said pivot axis substantially perpendicular to the direction of travel in a straight line of the vehicle; - The contact of an element of said contact-ground-secondary 3 with an obstacle mechanically causes the rotation of said cradle 60 about its pivot axis; the rotation of said mobile cradle in contact with an obstacle puts an element 13 of said first undercarriage into contact with an element of said second undercarriage 3; the rotation of said cradle 60 in contact with an obstacle lowers its axis of rotation; the rotation of said cradle 60 mechanically drives the downward movement of at least one element of said second undercarriage; said first undercarriage comprises only two wheels having the same axis of rotation; - the vehicle is a Segway; said second undercarriage pivots around an axis referred to as the real or virtual arm axis integral with the vehicle, said arm axis being substantially perpendicular to the direction of travel in a straight line of the vehicle; the vehicle comprises a wheel 1 and said second undercarriage is driven in motion by the rotation of said wheel 1 when it is in contact with an obstacle; said ground-secondary contact 3 is in the form of a curve, the point of which at every point crosses the vertical line passing through the center of gravity of said vehicle above this center of gravity; this curve is an arc whose center is higher than the center of gravity of said vehicle, - said contact-ground-secondary 3 is connected directly or indirectly to said frame 2 in two points, one of which is the crankpin of a crank turning about the arm axis 41; said cradle 60 is provided with a gearing 61 making it possible to move said ground-secondary contact 3 with respect to said cradle 60, and said gearing 61 is rotated by said wheel 1 when a part of said secondary undercarriage encounters an obstacle because the meeting of said secondary undercarriage with the obstacle causes a displacement of said cradle 60 contacting said gear 61 with said wheel 1; when said ground-secondary contact 3 is in its lowest position, its lowest part is substantially at the same height as said ground-primary contact 1 of said vehicle; the invention is a wheel 1 provided with at least one crossing aid device according to the invention; the invention is a vehicle provided with at least one crossing assistance device according to the invention; the vehicle comprises a front axle and a rear axle each provided with at least one device according to the invention; the vehicle is provided with a load-bearing element which can rotate relative to said chassis 2 about an axis substantially perpendicular to the direction of travel in a straight line of the vehicle; the vehicle is provided with a means for modifying the angular position relative to the frame of said load-supporting element about its pivot axis; the elasticity of a means for modifying the angular position relative to the chassis said load bearing member about its pivot axis constitutes a suspension; said ground-secondary contact 3 is connected directly or indirectly to said frame 2 by an elastic support which prevents it from cooperating with the wheel 1 when it encounters no obstacle; - An element of said contact-ground-secondary 3 rolls on the upper or lower part of a wheel 27 or two wheels 27 and 28 connected directly or indirectly to the frame 2; - Two second running gear are connected directly or indirectly to the frame 2 each by two crank pins 51a and 51b of the same crank 50, and rotate in phase shift; said secondary undercarriage is attached directly or indirectly to the frame 2 by two points which are both crankpins 50A and 50B rotating about fixed axes integral with the frame 2; - The vehicle is provided with a locking means of said secondary undercarriage in its lowest position; - The radii of the two cranks 50A and 50B are different, one of the two cranks can perform a complete revolution while the other is a round trip between two extreme positions; - The vehicle is provided with a wheel and said cradle 60 is pivotable about an axis substantially coincident with the axis of rotation of said wheel 1 with which it is associated; an elastic return prevents said primary gear 60 from cooperating with the wheel 1 when it encounters no obstacle; - The vehicle is provided with a biasing means of said secondary undercarriage in a so-called road position in which its rearmost portion 31 is kept close to or in contact with the ground; this horizontal movement consumes energy to dampen the shock with an obstacle; said ground-primary contact 1 is the lowest part of a wheel 1, and the vertical stroke of the foremost part of said secondary undercarriage is substantially greater than the radius of said wheel 1; said secondary undercarriage described during its rotation about said arm axis a circle whose radius is both greater than that of said wheel 1 and less than that of a circle of the same center as that of the rotation of said running gear secondary, but tangent to the furthest periphery of said wheel 1; said secondary undercarriage comprises a part cooperating with said wheel 1 so that, in a so-called locking position, it prevents said wheel 1 from rotating; a part of said second undercarriage is a ground connection device of a type known as a ski or an ice skate or an anti-slip means; two second running gear are arranged in series; said ground-secondary contact 3 is supported by a wheel 28 located substantially vertically from the axis of the point of tangency between said ground-secondary contact 3 and the running surface of said wheel 1; the mechanical connection between said ground-secondary contact 3 and said ground-primary contact 1 is an arm 4 whose one end is integral with said ground-secondary contact 3 and the other is fixed to the vehicle by an axis called arm 41 around which it can pivot, this arm axis being substantially perpendicular to the direction of movement of the vehicle, - said contact-ground-primary 1 is a wheel; the vertical travel of the most forward part of said ground-secondary contact 3 is substantially greater than one and a half times the radius of said wheel 1; said ground-secondary contact 3 described during its rotation about said arm axis a circle whose radius is both greater than that of said wheel 1 and less than that of a circle of the same center but tangential to the periphery the farthest from said wheel 1; said arm axis 41 is situated in front of the axis of said wheel 1, at a horizontal distance less than the length of the radius of said wheel 1; said ground-secondary contact 3 forms a wheel portion representing an arc of between 20 and 60 degrees; said ground-secondary contact 3 comprises a part cooperating with said wheel 1 so that, in a so-called locking position, it prevents said wheel 1 from rotating; - said ground-secondary contact 3 is driven in motion by the rotation of said wheel 1 when in contact with the ground; said ground contact 1 is provided with two crossing aids according to the invention situated on either side of said ground contact 1; the rolling surface of said ground-secondary contact 3 is substantially an arc of a circle; the assembly forming said contact-ground-secondary 3 is flexible to absorb shocks; said ground-secondary contact 3 is supported by a wheel 28 located substantially vertically from the axis of the point of tangency between said ground-secondary contact 3 and the running surface of said wheel 1; said caster 28 is motorized; said roller 28 is rotated by said wheel 1; said arm axis 41 can move horizontally when said ground-secondary contact 3 meets an obstacle, and comprises an elastic return towards its front position; - The crossing aid device comprises an elastic return of said arm shaft 41 to its forward position; the lowest part of said ground-secondary contact 3 is lower when said ground-secondary contact 3 goes back and forth than when it goes backwards and forwards; said arm axis 41 rolls on a first surface when the ground-secondary contact 3 goes back and forth, and follows a path in which the lowest part of the ground-secondary-contact 3 is higher when go back and forth; a part of said ground-secondary contact 3 is a ground connection device of a type known as a ski or an ice skate; - A connecting element connects by their front part two second running gear located on either side of said contact-ground-primary 1, and a stop prevents said connecting element from passing under said contact-ground-primary 1; said stop can be deactivated on command; - Two second running gear are arranged in series;

Brief description of the drawings The invention will be better understood, and other objects, advantages and characteristics thereof will appear more clearly on reading the description which follows, which is illustrated by the appended figures numbered from 1 to 61 which represent all devices according to the invention.

FIGS. 1 and 2 are side views of a device according to a preferred embodiment, in which a ground-secondary contact 3 is located at the end of an arm 4 connected to the frame 2 supporting the wheel 1, by an axis said arm axis 41 allowing the arm 4 and the contact-ground-secondary 3 to pivot back and forth. The device is in the so-called retracted position in FIG. 1 and in the so-called rest position in FIG. 2, the direction of the device being from left to right. Line portion of dashed circle makes it possible to measure the radius of the ferris wheel 1 which would have the same crossing capacity as the small wheel 1 equipped with the device according to the invention.

Figures 3 to 5 are perspective views of the same device, showing the successive steps of automatic crossing an obstacle from left to right. In FIG. 3, the ground-secondary contact 3 which is in the rest position abuts on the nose of a step, which forces it to pivot backwards by turning about said arm axis 4L. The arm 4 and the ground-secondary contact 3 which is integral thereto then pivot, as illustrated in FIG. 4, around the point of contact of the ground-secondary contact 3 with the nose of the step until said wheel 1 comes to it turns out to meet the walking nose as shown in Figure 5, which has the effect of losing the contact-ground-secondary contact with the ground 3. The arm 4 and the contact-ground-secondary 3 associated with it can then resume their rest position as shown in Figure 6.

Figures 7 to 10 are perspective views of the same device, showing the steps of the reverse movement, that of the descent of an obstacle from right to left. In FIG. 7, the ground-secondary contact 3 comes into contact with the nose of the step because said wheel 1 has left the top of the step, which forces it to pivot backwards, by turning around said arm axis 41. The arm 4 then pivots, as shown in FIG. 8, around its point of contact with the nose of the step until said wheel 1 comes in turn to meet the ground as illustrated in FIG. 9, which has the effect of losing the contact-ground-secondary 3 contact with the walking nose. The arm 4 and the contact-ground-secondary 3 associated with it can then resume their rest position as shown in Figure 10.

Figure 11 is a side view of a scooter equipped with a device according to the invention.

Figure 12 is a side view of a device according to the invention, in another embodiment. Figures 13 to 16 of the profile views of the device of Figure 12, showing the steps of crossing an obstacle from left to right. In FIG. 13, the elemental secondary-ground contact 3d comes into contact with the nose of the step, on which the whole vehicle carries its movement from left to right, its wheel 1 leaving the ground as illustrated in FIG. 14. In Figure 15, said wheel 1 comes into contact with the tread, which allows the ground-secondary contact to resume its rest position as shown in Figure 15. The vehicle then continues its route to the top of the march, ready for a new obstacle crossing.

Figures 17 to 19 show a variant of the invention which has the advantage of a smaller footprint.

Figure 20 is a perspective view of a device according to the invention operating both forward and backward. The arm 4 is disposed here in the middle of the ground-secondary contact 3, but it could as well be placed at one or other of its ends or at any other location.

Figures 21 to 23 are perspective views of a devil according to the invention. It is folded in FIG. 21 and in operation to the following, the ground-secondary contact in the rest position in FIG. 22 and working in FIG. 23.

FIGS. 24 and 25 are perspective views of an improved device comprising a pedal 37 making it possible to move it from the rest position in FIG. 24 to a locked position in FIG. 25, said wheel 1 on which the vehicle is resting being then immobilized by the faces 34a and 34b of the portion 34 of the ground-secondary contact 3.

Figures 26 to 28 illustrate another improvement of the invention, wherein said wheel 1 causes the ground-secondary contact 3 when in the working position. The arm 4 is decomposed into two parts 42 and 43 sliding one inside the other, so that the distance between said arm axis 41 and the ground-secondary contact 3 varies elastically between the rest position and the position working. In the working position, the ground-secondary contact 3 is pushed towards said arm axis 41 until it co-operates by its surface 33 with the surface 13 of said wheel 1. An elastic return moves the contact-sol- secondary 3 of said arm axis 41 when the ground-secondary contact is not in contact with any obstacle, and then suppresses this cooperation so that the arm 3 no longer rubs on said wheel 1.

Figure 29 shows a perspective view of a vehicle according to the invention, equipped with four ground-secondary contacts, one for each of its four wheels.

Figure 30 is a perspective view of a set of two devices according to the invention which are juxtaposed in series. Figure 31 is a side view of the same set.

FIGS. 32 to 34 are perspective views of the same device according to the invention, comprising two ground-secondary contacts 3a and 3b arranged in series, but sharing the same axis of arms 41.

FIG. 35 is a perspective view of a ground-secondary contact 3 connected to the chassis 2 of a vehicle by a virtual arm axis, constituted mechanically by four rollers 24A, 28B, 28C and 28D, which makes it possible to realize ground-side contacts of very large radius while limiting the size of the device.

Figures 36 and 38 are perspective views of a wheelchair according to the invention, having two pairs of ground-secondary contacts. The arms 3a and 3b in the foreground have their rear portion connected to the two cranks 51a and 51b of a crank 50 which rotates about the arm axis 4L In flat terrain, this wheelchair can roll on its wheels but it can also to cross obstacles and even to go up and down stairs with his contacts-ground-secondary which are motorized by the engine of the vehicle, which is here a Segway.

FIG. 37 is a side view of the same device according to the invention, which shows that in one of the possible positions, the ground-secondary contact 3a touches the ground and thus gives the vehicle stability at a standstill, because the center of the arc that constitutes the contact-ground-secondary is above the center of gravity of the vehicle in charge.

FIGS. 39 to 46 are perspective views of three variants of vehicles according to the invention which are two-wheeled vehicles or undercarriages having the same axis, for example gyropods, comprising secondary-ground contacts which are rails sliding around two casters secured to the frame 2. This is a particularly simple and compact way of implementing the invention.

In the first variant shown in Figures 39 to 41, the rollers 25 and 26 are fixed to the frame 2 by a block of flexible material (not visible in the figures) which allows a slight movement to each of the wheels, so as to allow the contacting the frictional friction zone 13 of the wheel 1 with the friction cooperation zone 33 of the ground-secondary contact when the ground-secondary contact encounters an obstacle, and only in this case.

In the second variant shown in Figures 42 to 46, it is a cradle 60 which receives the wheels 25 and 26, and this cradle can rotate freely about the axis of rotation of the wheels relative to the frame 2 of the vehicle. The position of the cradle can be determined by mechanical means, as is the case here by the fact that the rear part of the ground-secondary contacts is rectilinear and a slight spring (not shown) rotates the cradle around the axis of rotation of the wheel 1 until the rear part is close to the ground. Such an elastic return of the cradle 60, combined with a wheel placed at the rear of the ground-secondary contact, makes it possible to permanently maintain the rear part of the ground-secondary contact close to the ground, so that the end before the contact-ground-secondary is always the highest possible, and so he can cross the highest obstacles. Those skilled in the art can also design an electromechanical means, a sensor and a computer for defining an optimal inclination of the cradle according to the profile of the road.

Figures 45 and 46 illustrate a third variant with and without the body. We see in Figure 46 that the cradle tilts around the axis of rotation of the wheels, which allows to tilt the assembly to climb a staircase.

Figures 47 to 49 illustrate a fourth embodiment in which the second undercarriage 3 consists of two sets each consisting of three rollers and a crawler. The cradle 60 is here in two independent parts 60a and 60b, one per side, and can take different inclinations for each side. The cradle 60 is in the working position in FIGS. 47 and 48. In the rest position illustrated in FIG. 49, the ground contact 1 is the lowest point and the cradle is horizontal. When the second running gear encounters an obstacle, the front or rear roller raises and lowers the cradle. The lowest point is then the second running gear.

The track is driven by a portion 13 of the wheel 1, visible in Figure 49, which cooperates at its upper part with the interior of the central roller when the cradle 60 is in the working position.

Figures 50 to 52 illustrate a fifth variant which is a wheelchair and the second undercarriage comprises a cradle 60 supporting a crawler.

Figures 53 to 58 illustrate a sixth variant in which the ground-secondary contact 3 has the shape of a front bumper which is pivotable. It is in the rest position in FIGS. 53 and 54, and in the working position in FIGS. 55 and 56. The device is completed by a track 30 (FIGS. 53 55 and 57) or two tracks 30 and 30 A (FIGS. 58). These tracks are fixed on a secondary frame which comprises a gear connection with the wheels of the vehicle, which comes into contact with the front wheel only when said track encounters an obstacle.

Figures 59 to 61 illustrate a seventh embodiment in which the altitude of the contact-ground-secondary 3 is adjustable. The ground-secondary contact is in a rest position in FIG. 59, in the working position in FIG. 60, and in another rest position while waiting for an obstacle in FIG.

Detailed description of the invention

When an obstacle is of low height, the slope of the running surface of said wheel 1 at the point of contact with the obstacle is small, but when it is of greater height, this slope increases up to to reach 90 ° if the height of the obstacle is equal to or greater than the radius of said wheel 1. The obstacle is then impassable by the wheel 1.

The principle of the present invention consists in providing any means of support of a vehicle on the ground, such as a wheel 1 for example, a contact-ground-secondary 3 allowing it to rise gradually to the height of a obstacle to prevent him from stumbling on the obstacle. This device is not used permanently but only when the vehicle meets an obstacle, and is then returned to a rest position, either manually by the user, or preferably by an elastic return of the contact-ground-secondary 3 towards this rest position. This elastic return is not represented.

In the remainder of the description, an example is taken of a ground-primary contact 1 which is the lowest point of a wheel, but this wheel can be replaced by another means of contact between the vehicle and the ground, such as a contact-ground-secondary or a ski or a boat hull for example, or even by a first device according to the invention as illustrated in Figures 30 and 31.

The big difference with the crazy roller of the Citroëns of the Yellow Cruise in 1931 is that the diameter of this roller was very small, even lower than that of the wheels. He could not therefore cross very important obstacles, and a rock could even be crossed by the wheel and then get caught between the roller and the wheel 1.

An important advantage of the invention over the aforementioned documents US2002104692Al and US8764027B1 is that the ground-secondary contact is both the means for raising the vehicle above the obstacle, and also the detector for its implementation. automatic work, since it is the contact between the contact-ground-secondary and the obstacle that causes its passage from its so-called rest position to its so-called working position.

A second advantage over the prior art is that the device automatically resumes its so-called rest position after having been automatically put into operation, since it suffices to have a simple elastic return to obtain this repositioning when the contact-ground- secondary does not touch the ground anymore.

The ground-secondary contact 3 is located next to the ground support of the vehicle and shifted laterally so as not to conflict with it, which would occur if it were possible that, by moving back, it passes under said ground contact. -primary and gets stuck between him and the ground.

The ground-secondary contact 3 may be connected to the support of said wheel 1 by a mechanical connection 4 of any type known to those skilled in the art. FIGS. 12 to 16 show that the ground-secondary contact 3 may consist of a multitude of elementary ground-secondary contacts denoted 3a, 3b and following, which slide in a rail 32 which runs along the frame 2 supporting the wheel 1. The elementary ground-secondary contacts are connected to each other and can slide from the upper front part of the rail 32 denoted 321 to the rear end of this rail marked 322. The ground-secondary contact 3 can also cooperate with the chassis 2 by a wheel 36 which rolls on a rail 29. A wheel 28 secured to the frame 2 prevents the ground-secondary contact 3 to rise when it encounters an obstacle. The trajectory of the ground-secondary contact can be optimized by an appropriate drawing of the rail 29 and the shape of the ground-secondary contact 3.

The following four points are important: the mechanical link 4 must exist to guide the ground-secondary contact 3 when it is pushed backwards by an obstacle from its so-called rest position to its working position, then its position retracted. - The so-called rest position must be such that a front part of the ground-secondary contact 3 is situated above and in front of the ground support 1, so that this part of the ground-secondary-contact 3 comes into contact with a obstacle first, before the ground support 1. - At the end of the journey, the ground-secondary contact 3 must be in a so-called retracted position in which it must not touch the ground, to be able to return freely to the rest position . Its lowest part must therefore be located substantially above the ground support 1. - During its journey from its so-called rest position to its so-called retracted position, the ground-secondary contact 3 must pass through a position known as work in which at least a portion of the ground-secondary contact 3 is lower than its rest position. This is indeed the condition for the vehicle to be lifted by the contact-ground-secondary.

In a simple version, illustrated by FIGS. 1 to 11 and 20 to 31, the mechanical connection between the ground-secondary contact 3 and the support of said wheel 1 of the vehicle is said arm 4, one end of which is fixed to the ground contact. -secondaire 3 and the other rotates about an axis said arm axis 41 which is substantially parallel to the axis of rotation of said wheel 1. The end of the contact-ground-secondary 3 attached to the arm 4 described during this rotation a circle whose radius is less than that of a circle of the same center but tangential to the periphery of said wheel 1. In fact, if the ground-secondary contact was tangent to the periphery of said wheel 1, there is would have a stage of crossing the obstacle in which the arm and said wheel 1 would be simultaneously in contact with the obstacle, and it would be the contact-ground-secondary 3 which would then remain in contact with the obstacle, whereas that which is sought is instead that at the end of the franc hissement, it is said wheel 1 only remains in contact with the ground so that the contact-ground-secondary 3 can resume its rest position.

FIG. 31 makes it possible to understand that the lowest point of a ground-secondary contact in an arc of circle is advantageously placed at the intersection of its periphery with that of the running surface of said wheel 1, so as not to be lower down to a location further back where it would be no use and could be driven unnecessarily or hinder its return to the rest position, the center of this arc is advantageously located vertically this intersection.

Advantageously, the ground-secondary contact 3 forms a wheel portion whose axis of rotation is substantially coincident with the axis of rotation 41, and this wheel portion has a radius substantially greater than that of said wheel 1. thus replaced, only the time of crossing an obstacle, a wheel 1 by another of larger diameter, able to better cross the obstacle. This is illustrated in FIG. 2, in which the diameter of this large wheel, of which only one arc is used when necessary, has been shown by a dotted circle portion.

When the arm 4 is in its rest position, it is necessary that the lowest end of the periphery of the wheel portion formed by the ground-secondary contact 3 is substantially closer to the axis of rotation of the wheel. 1 as the periphery of the wheel 1, as this is a necessary condition for the contact-ground-secondary 3 can resume its rest position.

In a preferred embodiment, the ground-secondary contact forms a wheel portion representing an arc of between 20 and 60 degrees.

It is advantageous for the vehicle to have good longitudinal stability when it is placed on one or more ground-side contacts. For this, when the ground-secondary contact forms a wheel portion, it is necessary that the center of this arc is higher than the center of gravity of said vehicle. More generally, the curve formed by the lower part of the ground-secondary contact 3 must have at all points a normal which crosses above the center of gravity of the vehicle the vertical line passing through this center of gravity.

The ground-secondary contact 3 may comprise a rear portion opposite to the front portion, which is located above and behind the lower part of the vehicle. It can then move from the home position to the working position both forward and reverse, as shown in Figure 20.

The ground-secondary contact 3 may advantageously comprise a portion cooperating with said wheel 1 so that, in a so-called locking position, it prevents said wheel 1 from rotating. Such an improvement is shown in FIGS. 24 and 25. The resilience of the periphery of said wheel 1 is advantageously sufficient for the surface 34b to pass from one side to the other of said wheel 1 when the pedal is depressed. 37. This surface 34b, associated with the opposite surface 34a, then encloses said wheel 1 to prevent it from rotating. It must always be said wheel 1 which supports the vehicle, so that this maneuver immobilizes the device on its ground position.

The ground-secondary contact 3 can be collapsible or telescopic. Its rest position and / or its geometry can be modified to order of the user or automatically according to the inclination of the vehicle when it is a devil for example. The rest position can for example be modified so that the device takes up less space when it is not in use. The ground-secondary contact associated with a wheeled suitcase can for example be returned to the body of the bag when it is not desired to roll it, and automatically released to its so-called rest position when one draws on the handle of the bag. Those skilled in the art can also find many ways to fold the contacts-ground-secondary or any other element of the device according to the invention so that it occupies less space in storage position.

An improvement is to motorize the movement of the contact-ground-secondary when it encounters an obstacle, so that it is he who drives the movement of the vehicle. Any device for autonomous motorization or transmission to the ground-secondary contact of the energy of the main engine of the vehicle can be implemented, and the starting of this motorization of the movement of the contact-ground-secondary can be controlled by a first recoil of the ground-secondary contact when encountering an obstacle. One embodiment of this improvement, as illustrated in FIGS. 26 to 28, may be that the arm 4 is of variable length to allow or prevent the collaboration between a surface 33 of the ground-secondary contact 3 and a surface 13 of said wheel 1.

The ground-secondary contact may also be not rigid enough for its flexion when in contact with an obstacle to bring it closer to a rotating element with the wheel 1. Such a solution is shown in FIG. rear ground-secondary, right, are provided with a notched surface 33 which cooperates with a gear 13 on each of the rear wheels which are here the only drive wheels of the vehicle.

In these two variants shown in FIGS. 26 to 28 and in FIG. 29, the peripheral speed of the ground-secondary contact is not perfectly equal to that of said wheel 1, but the person skilled in the art can very easily introduce a transmission so that these speeds are perfectly equal (version not shown).

A ground-secondary contact 3 may be an arc of very great length when its axis of rotation is virtual as shown in FIGS. 35 and 39 to 46, or when its movement is not a rotational movement as in FIGS. It may even be of infinite radius, that is to say, perfectly flat, provided that its external front part, that which meets the obstacle first, is higher than the part in the center which follows. The ground-secondary contact associated with the rear wheel of a vehicle such as that represented in FIG. 29 could thus be practically flat and run from the rear of the front wheel to the rear of the rear wheel, such so that when the vehicle has crossed an obstacle with the help of its contact-ground-secondary before, its secondary contact-ground-secondary ensures the passage of the rear part. This almost flat secondary-ground contact can cooperate with a friction surface 13 of the wheel 1 with which it is associated, by its own friction surface 33.

It is often advantageous to use a flexible ground-secondary contact that can absorb shocks with the obstacles encountered. In this case, the ground-secondary contact is advantageously supported by a wheel 28 secured to the frame 2 of the vehicle. Such a wheel 28 is advantageously located substantially vertical to the axis of the point of tangency between the rolling surface of the ground-secondary contact 3 and the running surface of said wheel 1. Such a wheel 28 can be motorized by example independently or even rotated by said wheel 1.

Advantageously, the ground-secondary contact 3 can roll on the upper or lower part of two rollers 27 and 28 connected directly or indirectly to the frame 2 as shown in FIGS. 39 to 46. In these figures, the rollers roll inside the contact-ground-secondary where they are imprisoned and they guide perfectly the contact-ground-secondary 3.

The rollers 27 and 28 are advantageously fixed to the frame 2 by an elastic support which prevents the ground-secondary contact 3 from cooperating with the wheel 1 when it encounters no obstacle.

One solution for absorbing shocks is that the arm axis 41 can move elastically backward when the ground-secondary contact 3 encounters an obstacle. However, this movement must not be done simultaneously down too much, because this would affect the possibility of the contact-ground-secondary 3 to resume its rest position when not requested.

To limit the impact of the impact with an obstacle, the arm axis 41 can move substantially horizontally, for example along a slide, when it encounters an obstacle. The device of the invention can then participate in the safety of the occupants of the car in case of accident, which gives it an additional function. This horizontal movement advantageously consumes energy to dampen the shock with an obstacle.

The ground-secondary contact 3 can be fixed to the frame 2 each by two crank pins 51a and 51b of the same crank 50 and turn in phase shift. They are for example in phase opposition to Figures 36 to 38. The other ends of each of the ground-secondary contacts are attached to two other cranks 50a and 50b.

The ground-secondary contact 3 can also be fixed to the frame 2 at two points which are both crank pinches rotating about fixed axes integral with the frame 2. The radii of the two cranks may be different, one of the two cranks that can perform a complete turn while the other makes a round trip between two extreme positions.

It is advantageous in many cases that, when the ground-secondary contact 3 is in its lowest position, its lowest part is almost at the same height as said ground contact of said vehicle. By correctly determining the radius of curvature of the contact-ground-secondary, the vehicle then acquires a natural stability like a rocking chair, even when it comprises only two wheels like a Segway. In this case, the vehicle is advantageously provided with means for blocking the ground-secondary contact 3 in its lowest position. The advantage of the solution represented in FIGS. 36 to 38 is that there is a position, not shown, in which the lowest part of each of the two ground-secondary contacts is located at the same distance from the ground, and that they can both be put in the rest position so that they do not touch the small irregularities of the ground.

The vehicle can be equipped with a seat 7 or any other element supporting a load 70. In FIGS. 36 to 38, this load is a ball that represents the center of gravity of the assembly formed by the seat 7 and its passenger. (not shown) A possible improvement is that this seat can pivot about an axis perpendicular to the direction of movement of the vehicle, so that it remains stable regardless of the inclination of the frame 2. Advantageously, this axis is located above and substantially vertical to the center of gravity 70 so that the seat is in stable equilibrium. A control 71 secured to the frame 2, operated by hand or foot for example, can in this case to easily vary the position of the center of gravity 70 relative to the vehicle, which can be useful for controlling a Segway without having to move his body.

In a particular version not shown, a part of the ground-secondary contact 3 may be a ski or an ice skate, or any other mechanical device hanging better on the ground than a wheel. The commissioning of this element can be an effective backup solution when a car rolls on the ice, for example. It can also be the braking means of a roller skate or ice, serving in reverse, for example. The displacement of the ground-secondary contact 3 to put it in this configuration can be controlled by a computer. A connecting element can connect two ground-secondary contacts located on either side of said ground-primary contact 1 of a vehicle. This connecting element can be placed at the front of the device, but it is in this case desirable that a stop prevents this connecting element from passing under said contact-ground-primary. This stop may be deactivated on command, for example when the ground-secondary contact is an ice skate or a braking means.

In an improved version, two ground-secondary contacts may be arranged in series as shown in FIGS. 30 to 34. The ground-secondary contact 30 is located in front of the ground-secondary contact 3 and makes it possible to absorb the obstacles the higher. Its action is followed by that of the ground-secondary contact 3. The arrangement of Figures 32 to 34 is particularly advantageous for example to equip the wheel 1 before a scooter, because the size of the device in the retracted position is lower and that no moving element is more likely to come to touch the chassis 2 of the machine. That of Figures 30 and 31 has the advantage of reducing the inclination of the vehicle trajectory at the beginning of its ascent to a large obstacle.

A vehicle advantageously comprises a front axle and a rear axle each provided with at least one device according to the invention, but it is not essential. A particularly advantageous solution is to use several rear wheels placed one behind the other so that the vehicle is always supported by one of these wheels which can be small to increase the loading space of the vehicle. This solution is also very suitable for pallet trucks that can have multiple wheels under the blades supporting the pallets (not shown).

It is desirable that the movement of this arm axis 41 does not lower it too much, as this would impair the ability of the ground-secondary contact 3 to resume its rest position when no longer needed. However, this point becomes irrelevant when the shock is such that the designer of the device considers that the main function of the ground-secondary contact is then to limit the impact of the impact on the occupants of the vehicle.

It is advantageous to provide an elastic return to the front position of the arm axis 41, but manual or automated control can also recall it in this forward position.

An improvement not shown is to provide the contact-ground-secondary variable geometry so that it can integrate into the body when the profile of the land is not likely to make its use necessary. Those skilled in the art can even usefully provide it with an additional position in which it serves as a front shield to the vehicle, absorbing the energy of shocks with obstacles like other vehicles in case of pileup. The ground-secondary contact can also constitute in at least one of its positions a protection of mechanical members located at the front of the vehicle.

To simplify the discussion, the arm shaft 41 is always described as integral with the frame 2 of the vehicle. It may, however, without departing from the scope of the present invention to be secured to the frame 2 of the vehicle only by means of a cradle 60 which can pivot about an axis substantially perpendicular to the direction of movement of the vehicle. This makes it possible to adapt the geometry when climbing or descending a slope. Such a solution is shown in FIGS. 41 to 46. It is indeed important that the ground-primary contact of the vehicle can resume regular contact with the ground when the vehicle is traveling through a continuous series of obstacles, such as the steps of a stairway. example. Without this inclination of the cradle, steps too close together may not allow this resumption of contact, which is the necessary condition for the contact-ground-secondary can resume its rest position and therefore be ready to allow the crossing of a new obstacle by the vehicle.

Advantageously, when the vehicle is provided with a wheel 1, the cradle 60 can pivot about an axis substantially coinciding with the axis of rotation of the wheel 1 with which it is associated.

In this case, the cradle 60 is advantageously provided with one or more gears respectively referred to as the primary gear 61 and the secondary gear 62 transmitting the movement of the wheel 1 to the ground-secondary contact 3 when the latter encounters an obstacle. The elastic displacement of the cradle co-operates the zone 13 of frictional cooperation of the wheel 1 not directly with the ground-secondary contact 3 but with the primary gear 61 which in turn drives the gear 62, which displaces the contact-soil-secondary longitudinally. It is thus the encounter of the ground-secondary contact 3 with the obstacle which causes a displacement of the cradle 60 bringing the wheel 1 into contact with the primary gear 61. An elastic return prevents said primary gear 61 from touching the wheel 1 when the ground-secondary contact 3 encounters no obstacle. All transmissions may be contemplated by those skilled in the art, including the simplest such as a single belt or a single gear connecting the wheel 1 with the contact-ground-secondary when it meets an obstacle.

Figures 36 and 38 illustrate a particular implementation of such a drive of a ground-secondary contact. The cradle 60 is here provided with a cylinder 61 whose outer portion can cooperate by friction with the wheel 1 (not shown in FIG. 36 so that the cylinder 61 can be seen). When it is brought into contact with the surface 13 of the wheel 1, the cylinder 61 rotates and transmits its rotation by a toothed belt 80 to the crank 50 which causes the movement of the ground-secondary contacts 3a and 3b. Those skilled in the art can determine the radii of the cylinder 61 and of the one which is integral with the crank 50 to adjust the speed of translation of the ground-secondary contacts to that of the periphery of the wheel 1.

As shown in FIGS. 42 to 46, the rear portion of the ground-secondary-contact 3 is advantageously substantially straight so that its rear end 31 can be very close to the ground and provide a great stability to the vehicle as to a Segway or any other type of vehicle. train running at a stop. In this case in particular, the vehicle is advantageously provided with a return means of the contact-ground-secondary 3 in a so-called road position in which its rearmost portion 31 is kept very close or in contact with the ground. This means can be electronic, combining for example a ground proximity sensor and a motor modifying the orientation of the cradle relative to the chassis 2 of the vehicle, but it is also possible for simple and rustic vehicles to be content with a slight elastic return from the rear part of the ground-secondary contact to the ground so that it is the contact with the ground which determines its so-called road position. The rear part of the ground-secondary contact can be provided with a wheel for this purpose, to limit friction and noise.

In an optimized implementation for a wheelchair, represented in FIGS. 49 to 52, the cradle 60 has three main positions from rear to front, a so-called climb position illustrated in FIG. 5f, a so-called flat terrain position illustrated in FIG. FIG. 49 and a so-called descent position illustrated in FIG. 52. The cradle 60 is higher in the flat terrain position than in the other two positions, so that, in the flat ground position, the vehicle rests on said first running gear and in the up position and in the down position, it rests on said second undercarriage.

An improvement of this implementation consists in that an element 3 of said first undercarriage rotates an element of said 33 second undercarriage when the cradle is in the up position or in the descent position.

A further improvement consists in that an element 13 of said first undercarriage causes the cradle 60 to move as soon as the cradle has left its flat terrain position in the direction of its climbing position. In this case, the rotation of an element of said first undercarriage has the effect, as soon as the cradle has left its position of flat terrain, to raise the vehicle on the cradle until it reaches the position climb up if it is forward, and to get it up on the second running gear until it reaches the downhill position if it is in reverse. This cooperation between the cooperation element 13 of the first undercarriage and the cradle ceases as soon as the cradle has reached its climbing position or its descent position.

The vehicle is advantageously provided with a locking means of the cradle in the down position and in the up position.

To return from the climb position to the flat ground position, simply reverse, and to return from the downhill position to the flat terrain position, simply unlock the locking means of the cradle in the down position . The inclination of the cradle may be free or determined automatically by the soil profile. The inclination of the frame relative to the horizontal can be determined either manually or by a motor controlled by sensors as is the case for example if the vehicle is a Segway.

Advantageously, the second undercarriage is provided with freewheels and / or braking devices disengaged by the user to avoid going down a hill in forward or reverse without action of the user. The freewheel preventing going down in reverse is advantageously put into action as soon as the cradle is in the up position.

In an optimized implementation for a vehicle such as a mobile robot, represented in FIGS. 53 to 58, the ground-secondary contact 3 is substantially coincident with a part of the front bumper of the vehicle, and supplemented by one or two tracks that support the vehicle when the front wheels have crossed the obstacle. These tracks are advantageously supported by an autonomous frame 300, having a means of cooperation 310 with the drive wheels, so that they are motorized. An improvement is that this cooperation exists only when the autonomous frame 300 is pushed up when the track comes into contact with the ground. Such a solution is shown in FIGS. 53 to 58, in which the grooves 211 interacting with the lug 311 are distinguished. Those skilled in the art can arrange several devices on the different sides of a vehicle in the case where the latter is holonomic.

It is advantageous to be able to change the altitude of the contact-ground-secondary 3 because this makes it possible to better anticipate certain situations and to provide stability to the vehicle at a standstill. A vehicle with such a solution is shown in FIGS. 59 to 61. The invention is an accessory that can be added to a wheel 1 or to a vehicle, a wheel 1 provided with at least one device for assisting a vehicle. crossing according to the invention, for example two ground-side contacts according to the invention located on either side of the wheel 1, a vehicle of any kind comprising at least a device for aiding the crossing according to the invention.

applications

The present invention applies to motor vehicles including in particular off-road vehicles, tricycles and quads, two-wheelers such as bicycles, scooters and gyropods, wheelbarrows, devils, trolleys, caddies, wheeled skates, wheeled cases, wheelchairs, trolleys, robots and platforms supporting robots, toys, aircraft landing gear, boat trailers, cement mixers and Generally speaking, all equipment or objects that one wishes to be able to move easily without providing them with very large wheels.

Claims (65)

claims 1. Device for crossing a vehicle comprising: - a chassis (2), - a first undercarriage comprising one or more elements having a ground-contacting surface such as a wheel, called ground-primary contact ( 1) permanently supporting it when it is on level ground, - and a second undercarriage comprising one or more ground contact surfaces known as ground-secondary contact (3) - such as crawler rollers or a skid forming a wheel portion - said second undercarriage being connected directly or indirectly to the frame (2) of the vehicle by a mechanical connection (4), characterized in that: - said mechanical connection (4) guides an element of said ground contact -secondary (3) downwards when pushed backwards, from a so-called rest position in which - the front part of said ground-secondary contact (3) is located above and in front of the most bottom of said ground contact -primaire (1) of the vehicle, - the vehicle rests on the ground by said first undercarriage, no part of said contact-ground-secondary (3) does not touch the ground, to a so-called working position in which the vehicle rests on contact -sol-secondary (3), - that no part of said ground-secondary contact (3) is in contact with the ground when the vehicle is placed by its contact-ground-primary (1) on a flat horizontal ground said second running gear is provided with a restoring means at its rest position when it is not in contact with the ground, and said secondary-secondary contact is shifted laterally relative to contact-ground-primary audit (1), and at a sufficient lateral distance from the latter to not be able to get caught between said contact-ground-primary (1) and the ground. it being specified that above and hereinafter by obstacle is meant any part of the ground higher than that on which said first rolling element rests when said second running gear is in the rest position. 2. Crossing assistance device according to claim 1 characterized in that an element of said second undercarriage is driven in motion either by an independent motor or by mechanical cooperation with an element of said first undercarriage. 3. Assist device crossing according to claim 1 characterized in that, in the so-called rest position, no part of the ground-secondary contact (3) is driven in motion by a motor or by mechanical cooperation with an element of said first running gear. 4. Crossing assistance device according to any one of the preceding claims, characterized in that the passage of said second running gear in working position brings into contact a cooperating element (13) of said first running gear with a cooperation element. (33) of said second undercarriage. 5. Crossing assistance device according to claim 1 characterized in that, after passing through said work position, said second undercarriage reaches a so-called retracted position in which the lower part of said contact-ground- secondary (3) is higher than the lowest part of said contact-ground-primary (1), and therefore does not touch the ground. 6. assistance device crossing according to any preceding claim characterized in that the second running gear is connected to said frame (2) via a cradle (60) which can rotate around a axis said pivot axis substantially perpendicular to the direction of travel in a straight line of the vehicle. 7. Crossing assistance device according to claim 6 characterized in that the contact of an element of said contact-ground-secondary (3) with an obstacle mechanically drives the rotation of said cradle (60) about its pivot axis ; 8. Crossing assistance device according to claim 6 or claim 7, characterized in that the rotation of said mobile cradle in contact with an obstacle brings into contact an element (13) of said first undercarriage with an element of said second train. rolling (3); 9. Support device crossing according to any one of claims 6 to 8 characterized in that the rotation of said cradle (60) in contact with an obstacle lowers its axis of rotation. 10. Assist crossing device according to any one of claims 6 to 9 characterized in that the rotation of said cradle (60) mechanically drives the downward movement of at least one element of said second undercarriage. Additional claims 11. Crossing assistance device according to any preceding claim characterized in that said first undercarriage comprises only two wheels having the same axis of rotation; 12. Crossing aid device according to claim 1 characterized in that the vehicle is a Segway. 13. Crossing aid device according to claim 1 characterized in that said second undercarriage rotates about an axis called arm axis (41) real or virtual integral vehicle, said arm axis (41) being substantially perpendicular to the direction of travel in a straight line of the vehicle. Crossing assistance device according to any one of the preceding claims, characterized in that the vehicle comprises a wheel (1) and that said second undercarriage is driven in motion by the rotation of said wheel (1) when he is in contact with an obstacle. 15. Crossing assistance device according to any one of the preceding claims characterized in that said contact-ground-secondary (3) has the shape of a curve which, in every point, the normal crosses the vertical line passing by the center of gravity of the vehicle above that center of gravity. 16. Crossing aid device according to claim 1 characterized in that this curve is an arc whose center is higher than the center of gravity of said vehicle, 17. Crossing assistance device according to claim 2 and any one of claims 3 to 5 characterized in that said contact-ground-secondary (3) is connected directly or indirectly to said frame 2 in two points of which one is the crankpin of a crank turning about the arm axis 41. 18. A crossing aid device according to claim 3 and any one of claims 4 to 6, characterized in that said cradle (60) is provided with a gear (61) for moving said contact-sol- secondary (3) with respect to said cradle (60), and said gear (61) is rotated by said wheel (1) when a portion of said secondary undercarriage meets an obstacle, because the encounter of said secondary undercarriage with the obstacle causes a displacement of said cradle (60) contacting said gear (61) with said wheel (1). 19. Crossing aid device according to any one of the preceding claims, characterized in that when said ground-secondary contact (3) is in its lowest position, its lowest part is substantially at the same height. that said ground-primary contact (1) of said vehicle; 20. Wheel (1) provided with at least one crossing aid device according to the invention. 21. Vehicle provided with at least one crossing aiding device according to the invention. 22. Vehicle according to the preceding claim characterized in that it comprises a front axle and a rear axle each provided with at least one device according to the invention. 23. Vehicle according to the preceding claim provided with a load-bearing element characterized in that this element can rotate relative to said frame (2) about an axis substantially perpendicular to the direction of travel in a straight line of the vehicle. 24. Vehicle according to the preceding claim characterized in that it is provided with a means for modifying the angular position relative to the frame of said load-bearing member about its pivot axis, 25. Vehicle according to the preceding claim characterized in that the elasticity of a means for modifying the angular position relative to the frame of said load-bearing member about its pivot axis constitutes a suspension. 26. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) is connected directly or indirectly to said frame (2) by an elastic support which prevents it from cooperating with the wheel ( 1) when he does not encounter an obstacle; 27. Crossing assistance device according to claim 1 characterized in that an element of said contact-ground-secondary (3) rolls on the upper or lower part of a wheel (27) or two wheels (27 and 28) connected directly or indirectly to the frame (2). 28. Crossing assistance device according to claim 1 characterized in that two second rolling gears are connected directly or indirectly to the frame (2) each by two crank pins (51a and 51b) of the same crank (50), and rotate phase shift; 29. Crossing assistance device according to claim 1 characterized in that said secondary undercarriage is fixed directly or indirectly to the frame 2 by two points which are both crankpins (50A and 50B) rotating around axes fixed fixed to the frame (2). 30. Crossing aid device according to claim 1 characterized in that the vehicle is provided with a locking means of said secondary undercarriage in its lowest position; 31. Crossing assistance device according to claim 1 characterized in that the radii of the two cranks (50A and 50B) are different, one of the two cranks can perform a complete turn while the other makes a return trip between two extreme positions. 32. Crossing assistance device according to claim 1 characterized in that the vehicle is provided with a wheel and said cradle (60) is pivotable about an axis substantially coincident with the axis of rotation of said wheel (1) with which he is associated. 33. Crossing assistance device according to claim 1 characterized in that an elastic return prevents said primary gear (60) to cooperate with the wheel (1) when it encounters no obstacle. 34. Crossing assistance device according to claim 1 characterized in that the vehicle is provided with a return means of said secondary undercarriage in a so-called road position in which its rearmost portion (31) is maintained. near or in contact with the ground. 35. Crossing assistance device according to claim 1 characterized in that this horizontal movement consumes energy to dampen the impact with an obstacle; 36. Crossing assistance device according to any one of the preceding claims characterized in that said contact-ground-primary (1) is the lowest part of a wheel, and that the vertical stroke of the part la further forward of said secondary undercarriage is substantially greater than the radius of said wheel (1). 37. Crossing aid device according to claim 3, characterized in that said secondary undercarriage describes during its rotation about said arm axis a circle whose radius is both greater than that of said wheel (1) and less than that of a circle of the same center as that of the rotation of said secondary undercarriage, but tangential to the furthest periphery of said wheel (1). 38. Crossing aid device according to any one of claims 3 to 5 characterized in that said secondary undercarriage comprises a portion cooperating with said wheel (1) so that, in a so-called locking position, it prevents said wheel (1) to rotate. 39. Crossing assistance device according to any one of the preceding claims characterized in that a part of said second running gear is a ground connection device of a type known as a ski or an ice skate or a non-slip means . 40. Crossing assistance device according to claim 1 characterized in that two second running gear are arranged in series. 41. Crossing assistance device according to claim 3 characterized in that said contact-ground-secondary (3) is supported by a wheel (28) located substantially vertically to the axis of the point of tangency between said contact -sol-secondary (3) and the running surface of said wheel (1). 42. Crossing assistance device according to claim 1 characterized in that the mechanical connection between said contact-ground-secondary (3) and said contact-ground-primary (1) is an arm (4) whose one end is secured to said ground-secondary contact (3) and the other is fixed to the vehicle by an axis said arm axis (41) around which it can pivot, this arm axis being substantially perpendicular to the direction of movement of the vehicle, 43. Crossing assistance device according to claim 1 characterized in that said contact-ground-primary 1 is a wheel. 44. Crossing assistance device according to claim 1 characterized in that the vertical stroke of the foremost part of said ground-secondary contact is substantially greater than one and a half times the radius of said wheel (1), 45. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) described during its rotation about said axis of arms a circle whose radius is both greater than that of said wheel (1) and less than that of a circle of the same center but tangential to the furthest periphery of said wheel (1). 46. Crossing assistance device according to claim 1 characterized in that said arm axis (41) is located in front of the axis of said wheel (1) at a horizontal distance less than the length of the radius of the beam. said wheel (1). 47. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) forms a wheel portion representing an arc of between 20 and 60 degrees. 48. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) comprises a portion cooperating with said wheel (1) so that, in a so-called locking position, it prevents said wheel (1) to rotate. 49. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) is driven in motion by the rotation of said wheel (1) when in contact with the ground. 50. Crossing assistance device according to claim 1 characterized in that said ground contact (1) is provided with two crossing aids according to the invention, located on either side of said ground contact (1). ). 51. Crossing aid device according to claim 1 characterized in that the rolling surface of said contact-ground-secondary (3) is substantially a circular arc. 52. Crossing assistance device according to claim 1 characterized in that the assembly forming said contact-ground-secondary (3) is flexible to absorb shocks. 53. Crossing assistance device according to claim 1 characterized in that said contact-ground-secondary (3) is supported by a wheel (28) located substantially vertically to the axis of the point of tangency between said contact -sol-secondary (3) and the running surface of said wheel (1). 54. Crossing assistance device according to claim 1 characterized in that said wheel (28) is motorized. 55. Crossing assistance device according to claim 1 characterized in that said roller (28) is rotated by said wheel (1). 56. Crossing assistance device according to claim 1 characterized in that said arm axis (41) can move horizontally when said ground-secondary contact (3) encounters an obstacle, and comprises an elastic return towards its position. before; 57. Crossing assistance device according to the preceding claim characterized in that it comprises an elastic return of said arm axis (41) to its forward position. 58. Crossing assistance device according to claim 1, characterized in that the lowest part of said ground-secondary contact (3) is lower when said ground-secondary contact (3) goes back and forth. only when he goes back and forth. 59. Crossing assistance device according to claim 1 characterized in that said arm axis (41) rolls on a first surface when the ground-secondary contact goes back and forth, and follows a path in which the the lowest part of the ground-secondary contact is higher when it goes back and forth. 60. Crossing aid device according to claim 1 characterized in that a portion of said contact-ground-secondary (3) is a ground connection device of a type known as a ski or an ice skate. 61. Crossing assistance device according to claim 1 characterized in that a connecting element connects by their front part two second running gear located on either side of said contact-ground-primary (1), and that a stopper prevents said connecting element from passing under said ground-primary contact (1). 62. Crossing assistance device according to claim 1 characterized in that said stop can be deactivated on command. 63. Crossing assistance device according to claim 1, characterized in that two second rolling trains are arranged in series. 64. Crossing assistance device according to claim 1 characterized in that the vehicle is supported only by devices according to the invention. 65. LEGENDS 66. 192. 193. 194.