FR2818606A1 - Tracked vehicle for use on rough ground has track supporting wheels on beam in two articulated sections - Google Patents

Abstract

The vehicle has each or its metal or elastomer tracks (40) mounted on a frame with main (20, 30) and supporting (22, 34) wheels. The frame comprises front (12) and rear (14) beams articulated about a common pivot (16). The front beam is connected to the vehicle chassis (C) by a pivoted lever (44), while the rear beam is pivoted directly to the chassis, enabling each track assembly to fold in the middle and follow variations in the surface of the ground.

Description

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The invention relates to a caterpillar device suitable for driving on uneven terrain.

Tracked devices are already known which comprise a longitudinal frame, generally in the form of a beam, suitable for being mounted on a chassis of a vehicle and supporting two main wheels, sometimes also called end wheels, and support wheels around from which the caterpillar rolls up.

Such devices are advantageously used in all-terrain vehicles, such as agricultural, viticultural and oyster-farming vehicles, or even public and forestry works vehicles.

Such vehicles are generally equipped with two tracked devices, mounted respectively on the right side and on the left side of the vehicle chassis.

In the track devices known up to now, the longitudinal frame which supports the main wheels and the support wheels is produced in the form of a monobloc beam, one of the ends of which (most often the rear end) is articulated to the chassis, while the other end (most often the front end) is connected to the chassis via a suspension member. The beam can thus oscillate relative to the chassis according to a limited angular interval, which allows it to follow the profile of the terrain on which the vehicle is moving.

Usually, the tracked devices, located respectively on the right side and on the left side of the chassis, can oscillate independently of each other with respect to the chassis.

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In these known devices, one of the main wheels, generally that located towards the front of the frame, constitutes a tension wheel, which is non-driving, while the other main wheel, generally that located towards the rear of the beam, constitutes a driving wheel. In some cases, the axis of the drive wheel may coincide with the pivot or oscillation axis of the beam.

In these known devices, the actual track consists of an endless strip which can be formed from metallic elements, also called tiles, articulated between them, or be produced in the form of a flexible endless strip, advantageously made of elastomer.

A device of this type with an endless flexible strip is described in particular in French patents Nos. 93 13211 and 97 11398 in the name of the applicant.

The Applicant has posed the problem of improving the behavior of such a tracked device so that it adapts even better to the terrain on which it is moving, especially in the event that the terrain is uneven.

It has been found that, when a vehicle fitted with conventional crawler devices changes from horizontal movement to downhill movement, the device tends to tilt forwards and this suddenly, which in certain circumstances , may cause the vehicle to overturn.

Similarly, when the device changes from horizontal to uphill traffic, the vehicle tends to straighten suddenly, which again can cause accidents.

These phenomena are particularly accentuated when the center of gravity of the vehicle is in an elevated position as is the case for certain vehicles whose structure is at a level much higher than that of

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 tracks, and / or for vehicles carrying a high load.

A typical example of such vehicles is that of grape harvesting machines, or the like, which are designed to straddle crops and therefore have a particularly high center of gravity.

It is therefore an object of the invention to provide a crawler device, of the type defined above, which exhibits improved behavior for traffic in uneven terrain.

It is also an object of the invention to provide such a tracked device which can be applied to different types of vehicles or vehicles of the all-terrain type.

To this end, the invention provides a track device of the type defined above, in which the frame is formed by an anterior beam and a posterior beam located in the extension of one another and articulated together around 'a joint joint, in which the anterior beam comprises an anterior articulation disposed substantially in the center of the support length, in which the posterior beam comprises a posterior articulation disposed substantially in the center of the support length, and in which the one of the anterior joint and the posterior joint is articulated to the chassis, while the other of these two articulations is articulated to a lever, which is itself articulated on the chassis.

The frame of the device is thus formed from the combination of two beams hinged together, which provides a deformable track which best adapts to the terrain on which the device moves. Each of these beams comprises an articulation which is arranged substantially in the center of the support length, the latter being defined as the distance which separates the two wheels furthest from the beam which are supported on the ground. generally

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 ment, this distance corresponds to that which separates the respective supports from a main wheel (or end wheel) carried by the beam and from a support wheel, or intermediate wheel.

The fact that this articulation is located substantially at the center of this support length is important because it allows balancing at the support, both of the anterior beam and of the posterior beam.

In addition, one of these beams is articulated to the chassis, while the other is articulated to the chassis by means of a lever.

Preferably, the posterior articulation is articulated to the chassis, while the anterior articulation is articulated to the lever.

In one embodiment of the invention, one of the anterior articulation and the posterior articulation is articulated directly to the chassis, while the lever, which is connected to the other of these two articulations, is also articulated directly to the chassis.

In another embodiment of the invention, one of the anterior articulation and the posterior articulation is articulated to the chassis by means of a connecting rod, while the lever, which is connected to the other of these two joints, is articulated to the chassis by means of another connecting rod to form a toggle.

Thus, the frame (formed by the anterior beam and the posterior beam) is articulated, on the one hand by a connecting rod, and on the other hand by a lever-connecting rod assembly forming a toggle joint.

Advantageously, the posterior articulation is articulated to the chassis by means of one of the connecting rods, called the posterior connecting rod, while the anterior articulation is

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 articulated to the lever which is itself articulated to the chassis via the other connecting rod, called anterior connecting rod, to form said toggle joint.

According to another characteristic of the invention, the connecting rods are articulated respectively to two supports linked to the chassis, while a connecting member of variable length is articulated each time between the connecting rod and the chassis to vary the angular position of the connecting rod to the chassis.

This connecting member can be a jack, in particular a hydraulic jack. Such an actuator can for example be controlled from an appropriate hydraulic power unit, to allow the trim of the frame to be adjusted.

In another embodiment of the invention, the connecting member is a suspension member, in particular a spring.

According to another characteristic of the invention, one of the main wheels, in particular that carried by the front beam, is a tension wheel of the track, while the other main wheel, in particular that carried by the rear beam , is a driving wheel.

The track tension wheel is advantageously connected to the front beam by means of a tensioning and damping mechanism comprising a pressure-adjusted hydraulic cylinder and a spring.

As for the drive wheel, it can be coupled either to a motor, in particular a hydraulic motor, on board the beam, or to be coupled, via a transmission, to a motor on the chassis of the vehicle.

In the latter case, a single motor is used to transmit the movement to the drive wheels, located respectively on the right side and on the left side of the vehicle.

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 According to yet another characteristic of the invention, the front beam carries a deflection roller disposed above said beam and near the common articulation to serve as a deflection to an interior face of the track when the front beam s' tilts down from the rear beam.

Advantageously also, the lever carries a return roller disposed above the track to serve as a return to an outer face of the track when the front beam straightens upward relative to the rear beam.

In a preferred embodiment of the invention, the track is an endless flexible strip based on an elastomeric material. However, it is also within the scope of the invention to produce the track from articulated metallic elements, or even from a combination of flexible elements of the rubber type and metallic elements.

In the following description, given by way of example, reference is made to the appended drawings, in which: FIGS. 1, 2 and 3 are side views of a vehicle equipped with a tracked device, according to a first embodiment of the invention, for three different configurations of land; - Figures 4 to 6 are side views of a vehicle equipped with a tracked device according to a second embodiment of the invention, for three different terrain configurations; and FIG. 7 is a view similar to FIG. 6 in which the chassis of the vehicle is in the lowered position relative to the position of FIG. 6.

Reference is first made to FIGS. 1 to 3 which show an all-terrain vehicle V, such as an agricultural machine,

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 wine or oyster, or a public works or forestry machine. This vehicle, the structure of which is shown diagrammatically, comprises a chassis C which is also shown diagrammatically. This chassis carries, on each side, two tracked devices 10 of which only one, namely that located on the left side of the chassis, is shown in the figures. The device normally moves forward, as indicated by the AV arrow.

The device 10 comprises a longitudinal frame formed by an anterior beam 12 and a posterior beam 14 which are located in the extension of one another and which are articulated together around a common articulation 16 forming a pivot which extends horizontally and transversely to the chassis of the vehicle. At the front end of the front beam 12 is provided a wheel carrier 18 which supports a main wheel 20 also called tension wheel or non-driving wheel. The front beam 12 further carries four support wheels 22A, 22B, 22C and 22D, the wheel 22A being located near the main wheel 20 and the wheel 22D being located near the joint joint 16. In the example, these four wheels have the same diameter and have a smaller diameter than that of the main wheel 20.

It should be noted that the wheels 22B and 22C are supported by a bogie 24 itself articulated around a joint 26 which is located substantially in the center of the support length A of the beam 12. This support length corresponds at the distance to the ground defined between the respective points of contact of the wheels 22A and 22D with the ground, owing to the fact that the main wheel 20 is slightly raised relative to the ground.

The rear beam 14 carries, at its rear end, a wheel carrier 28 which supports a main wheel 30 which here constitutes a drive wheel. The wheel carrier 28 carries a motor 32, which is thus embedded on the beam, and which directly drives the wheel 30. It is advantageous to use a hydraulic motor connected by suitable hoses (not

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 shown) to a hydraulic unit on the vehicle chassis. This hydraulic unit also controls the analog motor carried by the device 10 located on the right side of the chassis.

It will be noted that the wheel 30 has a diameter greater than that of the wheel 20. The beam 14 further supports four support wheels 34A, 34B, 34C and 34D, the wheel 34A being near the joint joint 16 and the wheel 34D near the drive wheel 30. These wheels have the same diameter as that of the wheels 22A to 22D. As for the front beam, the two support wheels 34B and 34D are carried by a bogie 36 mounted oscillating around a joint 38.

Around the main wheels 20 and 30 and the support wheels 22A to 22D and 34A to 34D is wound a track 40 which is advantageously constituted by an endless flexible strip advantageously made of elastomeric material.

However, it is also within the scope of the invention to use other types of tracks, and in particular tracks made up of metal links hinged together.

The posterior beam 14 has a posterior articulation 42 which is located above the beam and which is disposed substantially at the center of the support length B of the beam, this support length being defined here by the distance between the respective points of contact of the wheels 34A and 30 with the ground. The articulation 42 is here directly connected to the chassis C of the vehicle.

The articulation 26 of the bogie 24 also constitutes an anterior articulation of the anterior beam 12. On this articulation 26 is articulated the end of a lever 44 whose other end is articulated around an articulation 46 on the chassis C of the vehicle. The joints 16, 26, 42 and 46 have respective axes parallel to each other and to the transverse direction of the chassis C.

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The lever 44 is advantageously a double lever comprising two parts respectively disposed on either side of the beam 12.

The wheel support 18 is connected to the beam by means of a tensioner and shock absorber mechanism 48 comprising a hydraulic cylinder 50 with adjusted pressure and a spring 52. This mechanism is of particular importance because it makes it possible to put the track energized and absorb length variations. The cylinder is adjusted to an adjusted pressure, while the spring is designed to absorb variations in length, for example when foreign bodies (stones, branches) are received between a wheel and the track.

The front beam 12 also carries a roller 54 disposed above the beam and near the common articulation 16 to serve as a reference to an inner face of the track when the front beam 12 tilts down relative to the posterior beam 14, as shown in FIG. 1.

In addition, the lever 44 carries a roller 56 which is here coaxial with the articulation 46. This return roller 56 is disposed above the track 40 to serve as a return to an external face of this track when the front beam 12 straightens up. upwards with respect to the rear beam as shown in Figure 2.

When the vehicle passes from a substantially horizontal surface to approach a descent (Figure 1), the frame of the device "breaks in two" and the two beams 12 and 14 which, initially, were substantially aligned (Figure 3), move angularly one relative to the other. It follows that the device best matches the variations in terrain configuration. Of course, the tracked device located on the right side also deforms independently.

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When the vehicle passes from a substantially horizontal surface to approach a climb (FIG. 2), the front beam 12 straightens with respect to the rear beam 14 to adapt to the configuration of the terrain. If the slope is greater, the outer face of the track abuts against the idler roller 56. In the position of FIG. 2, the track 40 is not yet in abutment with this idler roller.

On the other hand, when the vehicle is moving on substantially flat and regular terrain (FIG. 3) the beams 12 and 14 are practically in alignment with one another and struggle slightly with respect to each other .

We now refer to Figures 4 to 7 which show a more advanced embodiment than the previous one. The elements common to the embodiment of Figures 1 to 3 are designated by the same reference numerals.

The main difference here resides in the fact that the articulation 46 of the lever, instead of being connected directly to the chassis, is articulated at the end of a connecting rod 58 whose other end is articulated around a point d articulation 60 carried by a support 62 linked to the chassis C.

In addition, the articulation 42 of the rear beam 14, instead of being connected directly to the chassis, is connected to the end of another connecting rod 64, the other end of which is articulated at a point of articulation 66 on another support 68 fixed to the chassis of the vehicle.

The assembly formed by the lever 44 and the connecting rod 58 constitutes what may be called a toggle which deforms around the articulation 46.

It will be noted that the connecting rod 58 generally extends downwards and backwards from the articulation 60 and that, likewise, the connecting rod 64 generally extends downwards and rearwards from the hinge 66. These two

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 connecting rods may extend in approximately parallel positions, while the lever 44 is generally located in a substantially vertical position or at least close to the vertical.

Furthermore, two connecting members 70 and 72 of variable length are articulated each time between the connecting rod 58, respectively 64, and the chassis C to vary the angular position of the connecting rod relative to the chassis.

In the example shown in FIGS. 4 to 7, the connecting member 70 is a jack, in particular a hydraulic jack, which comprises a body 74 articulated at 76 on the chassis and a rod 78 articulated at 80 on the connecting rod 58, at an intermediate point between the joints 46 and 60. Likewise, the connecting member 72 is a jack, in particular a hydraulic jack which comprises a body 82 articulated at 84 on the chassis and a rod 86 articulated at 88 on the connecting rod 64, at an intermediate point between the joints 42 and 66. The jacks 70 and 72 are designed above all to allow adjustment of the height or trim of the vehicle chassis relative to the two tracks. This trim adjustment can be done independently for each of the two devices.

This is particularly of interest in vehicles such as grape harvesting machines or the like, the chassis of which must be able to be raised to span crops. The hydraulic cylinders are then connected to a suitable hydraulic unit (not shown) and controlled so as to adjust the attitude of the vehicle according to the wishes of the user.

For example, the jacks can be deployed to allow the chassis to be raised as shown in FIG. 6 (displacement in horizontal or substantially horizontal terrain).

On the other hand, when the vehicle passes over substantially horizontal terrain to approach a descent (FIG. 5), or on the contrary to approach an uphill (FIG. 4), it may

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 interesting to retract the two jacks to lower the vehicle chassis and therefore its center of gravity.

As can be seen in FIG. 7, the two jacks are in the retracted position, so that the connecting rod 58 is practically horizontal and the chassis of the vehicle is lowered as far as possible. In this position, the outer face of the track comes to bear against a deflection roller 90 carried by the chassis of the vehicle.

In another alternative embodiment (not shown), the two aforementioned connecting members (jacks 70 and 72) can be replaced by simple springs or dampers.

Of course, the invention is not limited to the embodiments described above by way of example, and it extends to other variants.

Thus, the lever could be articulated to the posterior beam, instead of the anterior beam.

In addition, it can be envisaged to use different types of tracks.

Furthermore, it will be understood that the number of support wheels for each of the front and rear beams is likely to vary depending in particular on the dimensions of the device.

Claims (15)

claims  1. Tracked device, comprising a longitudinal frame suitable for being mounted on a chassis of a vehicle and supporting two main wheels (20,30) and support wheels (22,34) around which the track (40) is wound. ), characterized in that the frame is formed by an anterior beam (12) and a posterior beam (14) located in the extension of one another and articulated together around a common articulation (16 ), in that the anterior beam (16) comprises an anterior articulation (26) disposed substantially in the center of the support length (A), in that the posterior beam (14) comprises a posterior articulation (42) disposed substantially in the center of the support length (B), and in that one of the anterior articulation (26) and the posterior articulation (42) is articulated to the frame (C), while the other of these two articulations is articulated to a lever (44), which is itself articulated to the chassis (C). 2. Device according to claim 1, characterized in that the rear articulation (42) is articulated to the frame (C), while the anterior articulation (26) is articulated to the lever (44). 3. Device according to one of claims 1 and 2, characterized in that one of the anterior articulation (26) and the posterior articulation (42) is articulated directly to the frame (C), while the lever (44), which is connected to the other of these two articulations, is also articulated directly to the chassis (C). 4. Device according to one of claims 1 and 2, characterized in that one of the anterior articulation (26) and the posterior articulation (42) is articulated to the frame (C) by means of a connecting rod (64), while the lever (44), which is connected to the other of these two articulations- <Desc / Clms Page number 14>  tions, is articulated to the frame (C) via another connecting rod (58) to form a toggle. 5. Device according to claims 2 and 4, taken in combination, characterized in that the rear articulation (42) is articulated to the chassis by means of one of the connecting rods (64), called the rear connecting rod, while the 'anterior articulation (26) is articulated to the lever (44) which is itself articulated to the chassis (C) by means of the other connecting rod (58), called the anterior connecting rod, to form the said toggle joint. 6. Device according to one of claims 4 and 5, characterized in that said connecting rods (58,64) are articulated respectively to two supports (62,68) linked to the chassis (C), and in that a member of link (70,72) of variable length is articulated each time between the connecting rod (58,64) and the chassis (C) to vary the angular position of the connecting rod relative to the chassis. 7. Device according to claim 6, characterized in that the connecting member (70,72) is a cylinder, in particular a hydraulic cylinder. 8. Device according to claim 6, characterized in that the connecting member (70,72) is a suspension member, in particular a spring. 9. Device according to one of claims 1 to 8, characterized in that one (20) of the main wheels, in particular that carried by the front beam (12), is a tension wheel of the track (40) , while the other main wheel (30), in particular that carried by the rear beam (14), is a driving wheel. 10. Device according to claim 9, characterized in that the tension wheel (20) of the track is connected to the front beam (12) by means of a mechanism <Desc / Clms Page number 15>  tensioner and shock absorber (48) comprising a pressure-adjusted hydraulic cylinder (50) and a spring (52). 11. Device according to claim 9, characterized in that the driving wheel (30) is coupled to a motor (32), in particular a hydraulic motor, on board the beam (14). 12. Device according to claim 9, characterized in that the driving wheel (30) is coupled, via a transmission, to an engine on board the chassis (C) of the vehicle. 13. Device according to one of claims 1 to 12, characterized in that the front beam (12) carries a deflection roller (54) disposed above said beam and near the joint joint (16) to serve of return to an inner face of the track (40) when the front beam (12) tilts down relative to the rear beam (14). 14. Device according to one of claims 1 to 13, taken in combination with claim 2, characterized in that the lever (44) carries a deflection roller (56) disposed above the track (40) to serve as return to an outer face of the track when the front beam (12) straightens upward relative to the rear beam (14). 15. Device according to one of claims 1 to 14, characterized in that the track (40) is an endless flexible strip based on an elastomeric material.