Three-point hitch with hydraulic shock absorber

Abstract

The present invention relates to a three-point hitch for connecting a machine (3) to a tractor (5), comprising two lower arms (1) configured to be fixed by a rigid attachment at two lower points (2) of the machine (3), and by a lower link (4) articulated to the tractor (5), and an upper device (6) configured to connect a third point (7) of the machine (3), located higher than the two lower points (2), to a point of a lifting device on the tractor (5). This upper device (6) of the hitch includes a hydraulic damper (8) equipped with a cylinder (9), configured to limit the forces transmitted by the upper device (6) to the tractor (5) beyond a predetermined force. Abstract figure: [Fig. 1]

Description

Title of the invention: Three-point hitch with hydraulic shock absorber

[0001] The present invention relates to the field of hitches for machines mounted on tractors. It relates more particularly to a three-point hitch with a hydraulic shock absorber.

[0002] Roadside maintenance primarily involves articulated arm flail mowers (FAFMs) attached to agricultural tractors. The large number of work sites and the extensive road network necessitate long distances between them. To facilitate this, the mower is folded behind the tractor, allowing the tractor to be used at its maximum speed. While the maximum speed was long limited to 40 km / h, some tractors are now capable of reaching speeds of up to 60 km / h.

[0003] Most machine hitches are achieved by articulating two arms attached to the machine on axles fixed to the tractor near its rear axle. A third point on the machine is connected to a lifting device on the tractor, which allows the machine to be held, raised, or lowered.

[0004] During operation, this three-point linkage is subjected to acceptable stress. However, during transport, the forces transmitted by the machine to the three-point linkage are greater; the machine's vertical accelerations due to road irregularities amplify these forces, potentially damaging the linkage on both the machine and tractor sides. This phenomenon is exacerbated by higher travel speeds, up to 60 km / h.

[0005] There are several damping systems for the third point of a three-point hitch, in particular to reduce the shocks experienced by the driver, the tractor, or the machine.

[0006] Other solutions propose a reinforcement of the third point attachment, to support the stress peaks, or even ancillary devices for stabilizing this attachment to reduce the stress peaks.

[0007] However, this has significant drawbacks, since they do not provide satisfactory protection.

[0008] There is therefore a need for a less expensive solution for the protection of tractors, drivers and machines, making it possible to avoid excessive stress, particularly during transport phases.

[0009] The present invention aims to overcome, at least in part, these drawbacks. To this end, it proposes a three-point hitch for connecting a machine to a tractor, comprising two lower arms configured to be fixed by a rigid attachment at two lower points of the machine and by a lower articulated link to the tractor, or alternatively by an articulation at two lower points of the machine and by a rigid lower link to the tractor, and an upper device configured to connect a third point of the machine, located higher than the two lower points, to a point on a tractor lifting device. The hitch is distinctive in that said upper device includes a hydraulic damper equipped with a cylinder, configured to limit the forces transmitted by the upper device to the tractor beyond a predetermined force.

[0010] Thanks to these provisions, the machine, the coupling components, and the tractor are protected from forces exceeding a predetermined limit, which allows the life of the components to be extended.

[0011] According to other characteristics

[0012] - said hydraulic shock absorber may include an accumulation system hydraulic coupled to at least one unidirectional flow restriction, forming an efficient and reliable system of the invention,

[0013] - the predetermined effort can be set greater than the efforts applied to said third The point when the machine is in operation, and lower than the maximum forces applied at said third point possible during the transport phase, thus allowing efficient work without any disruption, and the possibility of rapid transport.

[0014] - said upper device may include a connecting rod comprising a shaft of a machine, a central axis and a cylinder axis, said connecting rod of the machine being fixed in an articulated manner by its machine axis to said third point, and by its cylinder axis to said cylinder, said upper device comprising a tractor connecting rod having a main axis and a damping axis spaced apart from each other, and fixed to a tractor lifting device, said tractor connecting rod being fixed in an articulated manner by its main axis to said central axis of the connecting rod of the machine, said upper device comprising said cylinder, fixed in an articulated manner between said cylinder axis of the connecting rod of the machine and said damping axis of the connecting rod of the tractor; such arrangements allow the selection of a commercially available cylinder to perform the complex function implemented by the invention,

[0015] - said connecting rod of the machine may have a V-shaped form, the central axis being arranged at The base of the V and the machine and cylinder axes at the two highest points of the V, allowing for optimized conditions to make cylinder selection easier.

[0016] - the cylinder axis of the machine connecting rod can be further from the central axis than the machine axis, thus reducing the force required from the cylinder,

[0017] - the two arms of the V can form an angle greater than 90° with each other, thus freeing a larger space for installing the jack,

[0018] - the damping axis of the tractor connecting rod can be arranged higher than its main axis, thus allowing the cylinder to be positioned on top of the hitch, and facilitating its connection and maintenance,

[0019] - the upper device can be connected to the tractor lifting device by several axles, allowing the coupling of heavier machines.

[0020] The advantage provided by the present invention lies mainly in the fact that it allows efficient work of the machine while allowing rapid transport with a reduced risk of damage to the machine or tractor.

[0021] The present invention will be better understood upon reading the following detailed description made with reference to the accompanying figures in which

[0022] [Fig-1] is a side view of a coupling according to the invention,

[0023] [Fig.2] is a schematic view of a hydraulic system implemented in the hitching of the [Fig.l].

[0024] The hitch according to the invention shown in [Fig.1] comprises two lower arms 1, fixed by a rigid fixing at two so-called lower points 2 of the machine 3, and by a so-called lower link 4 articulated at a fixed point of the tractor 5. It can also be provided that the rigid fixing at the two so-called lower points 2 of the machine 3 are replaced by joints, and the so-called lower link 4 is then rigid.

[0025] The coupling according to the invention comprises an upper device 6; this connects a third point 7 of the machine 3, arranged higher than the two so-called lower points 2.

[0026] According to the invention, the upper device 6 comprises a hydraulic damper 8 equipped with a cylinder 9 and configured to limit the forces transmitted by the upper device 6 to the tractor 5 beyond a predetermined force. The predetermined force can then be adjusted so that during working phases this force is not reached; the hydraulic damper 8 then behaves like a rigid rod, and the machine 3 can operate satisfactorily.

[0027] If during a transport phase the predetermined effort is exceeded, the hydraulic damper 8 comes into action and dampens the peaks of effort; it thus prevents the upper device 6 from transmitting the peaks of effort, which makes it possible to put less stress on both the machine 3 and the tractor 5, and therefore also on the driver.

[0028] According to a preferred embodiment of the invention, the upper device 6 may include a connecting rod 10 comprising a machine shaft 11, a central shaft 12 and a cylinder shaft 13, said connecting rod 10 being fixed in an articulated manner by its machine shaft 11 to said third point 7, and by its cylinder shaft 13 to said cylinder 9.

[0029] According to this same preferred embodiment of the invention, said upper device 6 comprises a lifting beam 14 having a main axis 15 and a damping axis 16 spaced apart from each other, and fixed to a tractor lifting device 5, said tractor rocker arm 14 being fixed in an articulated manner by its main axis 15 to said central axis 12 of the connecting rod of the machine 10. Said cylinder 9 is fixed in an articulated manner between said cylinder axis 13 of the connecting rod of the machine 10 and said damping axis 16 of the rocker arm 14.

[0030] According to a particular embodiment of the invention, the machine connecting rod 10 has a V-shaped form, the central axis 12 being disposed at the base of the V and the machine axes 11 and cylinder axes 13 at the two high points of the V. This arrangement is considered verified within the scope of the present invention if the three axes connected by a straight line form a V; in general the connecting rod itself takes the form of a V, but it can be imagined that the connecting rod takes a different shape, due to the addition of additional elements fulfilling other functions.

[0031] When the three axes of the connecting rod 10 form a V, this facilitates the placement of a cylinder 9 between the cylinder axis 13 and the rocker arm 14, and allows the use of a shorter connecting rod 10, rocker arm 14, and cylinders 9. This reduces the overall size of the upper device 6 and its cost.

[0032] According to another particular embodiment of the invention, the cylinder axis 13 of the machine connecting rod 10 is further from the central axis 12 than the machine axis 11; this allows the use of a cylinder 9 of less force, and again reduces costs and space.

[0033] According to another particular embodiment of the invention, the two arms of the V form an angle greater than 90° between them; this makes it possible to further reduce the bulk.

[0034] According to another particular embodiment of the invention, the upper device 6 is connected to the tractor lifting device 5 by several axes, which gives more possibilities for heavy machines in particular.

[0035] According to another embodiment illustrated in [Fig. 2], the cylinder 9 can be connected to one or more hydraulic accumulators 17 coupled to at least one unidirectional flow restriction 18, allowing adjustment of the hydraulic damper 8. When the machine undergoes downward vertical acceleration, it is inactive, and it engages when the machine ascends. The hydraulic accumulator system releases the oil stored during the descent; the damper then dissipates a large part of the energy and prevents an upward shock due to rebound following the vertical acceleration. The hydraulic damper 8 can then be adjusted so that it behaves like a rigid rod up to the predetermined force and absorbs part of the force and energy when the load exceeds the predetermined force. The predetermined force can, for example, correspond to a vertical acceleration of 2G.

[0036] According to another particular embodiment of the invention, the damping axis 16 of the tractor connecting rod 14 is arranged higher than its main axis 15; this allows better accessibility for the connections of the cylinder 9 to the hydraulic accumulator 17, and therefore facilitates the assembly of the hitch and its maintenance.

[0037] The user, when traveling to a worksite, makes the road journey with the machine folded and does not need to make any changes to the hitch. As soon as the user goes over a bump causing greater stress, the hydraulic shock absorber 8 according to the invention comes into operation, and the forces applied to the machine 3, the hitch, and the tractor 5 remain within acceptable limits.

[0038] When the user arrives at a worksite, he positions himself, then lowers the machine 3, and he is operational to carry out mowing or brush clearing, without having to change any setting on the hitch.

[0039] Although the above description is based on particular embodiments, it is in no way limiting of the scope of the invention, and modifications may be made, in particular by substitution of technical equivalents or by different combination of all or part of the features developed above.

Claims

Demands

1. A three-point hitch for connecting a machine (3) to a tractor (5), comprising two lower arms (1) configured to be fixed by a rigid attachment at two so-called lower points (2) of the machine (3), and by a so-called lower link (4) articulated to the tractor (5), or alternatively by an articulation at two lower points (2) of the machine (3), and by a so-called lower link (4) rigid to the tractor (5), and an upper device (6) configured to connect a third point (7) of the machine (3) disposed higher than the two so-called lower points (2), to a point of a lifting device of the tractor (5), characterized in that said upper device (6) comprises a hydraulic damper (8) equipped with a cylinder (9), configured to limit the forces transmitted by the upper device (6) to the tractor (5) beyond a predetermined force.

2. Coupling according to the preceding claim, wherein said hydraulic damper (8) comprises a hydraulic accumulation system (17) coupled to at least one unidirectional flow restriction (18).

3. Coupling according to any one of the preceding claims, wherein the predetermined force is set greater than the forces applied at said third point (7) when the machine (3) is in working phase, and less than the maximum of the forces applied at said third point (7) possible in transport phase.

4. Coupling according to any one of the preceding claims, wherein said upper device (6) comprises a connecting rod (10) having a machine shaft (11), a central shaft (12) and a cylinder shaft (13), said connecting rod (10) being hinged by its machine shaft (11) to said third point (7), and by its cylinder shaft (13) to said cylinder (9), said upper device (6) comprising a tractor connecting rod (14) having a main shaft (15) and a damping shaft (16) spaced apart, and attached to a tractor lifting device (5), said tractor connecting rod (14) being hinged by its main shaft (15) to said central shaft (12) of the connecting rod (10), said upper device (6) comprising said cylinder (9), hinged between said cylinder shaft (13) and said damping axis (16).

5. Coupling according to the preceding claim, wherein said connecting rod of machine (10) has a V shape, the central axis (12) being disposed at the base of the V and the axes of machine (11) and cylinder (13) at the two high points of the V.

6. Coupling according to the preceding claim, wherein the cylinder axis (13) of the machine connecting rod (10) is further from the central axis (12) than the machine axis (11).

7. Coupling according to one of claims 5 or 6, wherein the two arms of the V form an angle greater than 90° with each other.

8. Coupling according to any one of claims 5 to 7, wherein the damping axis (16) of the tractor connecting rod (14) is arranged higher than its main axis (15).

9. Coupling according to any one of the preceding claims, wherein the upper device (6) is connected to the tractor lifting device (5) by several axes.

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