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(11) | EP 0 957 208 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Shovel arm for earth-moving vehicles |
| (57) The present invention relates to a shovel arm for earth-moving vehicles comprising:
a support arm (8) connected to the body of an earth-moving vehicle (3) by means of
a first hinge (11) and to a working part (5) by means of a second hinge (13); a raising
actuator (6) mounted on the body of the vehicle (3) by means of a third hinge (14)
and connected to the support arm (8) by means of a fourth hinge (16); an operating
actuator (7) also connected to the body of the vehicle (3) by means of a fifth hinge
(17) and to a first end (18) of a lever (19) by means of a sixth hinge (20). The lever
(19) is in turn connected, at its second end (21), to the support arm (8) and to the
raising actuator (6) by means of the fourth hinge (16). A connecting rod (22) is also
provided, being connected to the working part (5) by means of a seventh hinge (24)
and connected to the operating actuator (7) and to the first end (18) of the lever
(19) by means of the sixth hinge (20). |
[0002] The shovel arm in question may be advantageously used in the front part of earth-moving vehicles to support a bucket or a pallet-raising fork or a snow-clearing blade or a multiple-use bucket or a mixing bucket for concrete or other working parts.
[0003] Below reference will be made to a shovel arm for supporting a bucket, it being understood that the comments made below may equally well refer to an arm for supporting and moving any other working part.
[0004] At present, as is known, the moving of shovel arms is performed by means of a kinematic system which involves a plurality of mechanical parts which are operationally connected together so as to allow raising and movement of the bucket.
[0005] In particular it is known that, during raising of the arm by means of actuation of a hydraulic raising jack, the bucket must be able to move upwards, remaining substantially parallel to itself. This is in fact to ensure that the load present in the bucket does come out during raising of the arm.
[0006] For this purpose two different types of operating systems are commonly used to ensure correct execution of the arm moving operations.
[0007] A first type of system is based on the principle of hydraulic compensation of the bucket position. As is known, the bucket is mounted on the free end of the shovel arm by means of hinges which allow rotation thereof about an axis transverse to the arm itself, controlled by a bucket moving jack.
[0008] Therefore, during raising and lowering of the arm, the hydraulic compensation system automatically actuates rotation of the bucket so as to allow optimum positioning at whatever height the bucket is situated. In particular, therefore, this system allows the bucket to remain substantially parallel to itself when only raising of the load is envisaged.
[0009] This system, in order to operate, needs a fairly complicated hydraulic control circuit which requires a large number of components which result in difficult assembly and the execution of difficult and repetitive adjustments.
[0010] A second type of operating system is based on the principle of mechanical compensation by means of which, via a composite structure of mechanical parts which are connected together, movement of the arm is permitted, allowing the bucket to be kept always in the correct operating position.
[0011] Figures A and B show two different shovel arms of the known type, both based on the said principle of mechanical compensation.
[0012] As can be noted, both the shovel arms shown comprise, on each side of the shovel arm, a support arm (a) hinged at one end on with a bucket (b) and at the other end with the body of the earth-moving vehicle (not shown) at (o).
[0013] Two hydraulic jacks are also provided, consisting of a jack (c) for raising the shovel arm, hinged at one end with the support arm (a) and at the other end with the body of the vehicle at (w), and a jack (d) for operating the bucket (b), designed to connect the body of the vehicle to the bucket (b) by means of a mechanical transmission mechanism comprising various parts.
[0014] In particular, in the arm of the known type illustrated in Fig. A, the jack (d) for operating the bucket (b) is hinged at (v) with the vehicle and at the other end with a middle point of a lever (e) hinged in turn at one end with the support arm (a) and at the other end with a connecting rod (f) connected via a hinge to the bucket (b).
[0015] The operating jack (d) of the shovel arm shown in Fig. B is hinged at one end with a lever (g) in turn hingeably mounted in a central zone on the support arm (a) and hinged at the opposite end to the operating jack (d) with a crank (m) connected to the body of the vehicle. The other end of the operating jack (d) is connected to the bucket (b) by means of connecting rod (p) and to the support arm (a) by means of a second lever (r).
[0016] As can be clearly seen from Figures A and B, the mechanical structures which make up the two shovel arms illustrated are subject to geometric modifications depending on the movements of the arms themselves, which are controlled by the jack performing raising between two end positions, i.e. a fully raised position and a full lowered position. By means of these geometric modifications, the mechanical structures of the arms allow the buckets (b) to remain substantially always parallel to themselves in any position of the shovel arm (obviously this refers to operations in which only raising or lowering of the bucket is performed).
[0017] The geometric structures of the mechanical parts which make up the various shovel arms all satisfy a plurality of requirements of a technical nature.
[0018] In particular, it must be remembered, in order to understand more fully the reasons underlying the complexity of the kinematic systems for moving the shovel arms, that the mechanical structures of the arms are the result not only of requirements of a kinematic nature relating to movement of the working part but also structural requirements relating to distribution of the forces as well as the need to connect the hydraulic jacks, in precise positions, to the body of the vehicle so as to allow the jacks themselves to work in an optimum manner.
[0019] In accordance with the known art, the need to satisfy these requirements of a technical nature has hitherto always resulted in the realization of mechanical structures for shovel arms which are provided with a plurality of hinging points in order to obtain correct operation of the bucket moving mechanisms.
[0020] In fact, as can be seen from the two examples shown in the accompanying Figures A and B, the shovel arms have respectively nine and eleven different hinging points. This results in a high degree of complexity with regard to assembly of the shovel arms and the need to use a large number of mechanical components and therefore, ultimately, the drawback of a high degree of play and areas subject to wear.
[0021] It should also be remembered that mechanical structures composed of numerous elements such as those of the known type mentioned above result in fairly large dimensional volumes, this negatively affecting, in some operating conditions, good visibility from the operating cab. In other words, the operator must be able to view the movement of the bucket from the operating cab and may therefore be penalized when carrying out his duties by large dimensions of the shovel arm.
[0022] Therefore the highly articulated structure of the shovel arms known hitherto represents per se a further disadvantage of the mechanical structures of the known type which make up the arms themselves.
[0023] The main object of the present invention is therefore that of eliminating the drawbacks of the art known hitherto by providing an improved shovel arm for earth-moving vehicles, which is able to satisfy all the constructional requirements of a technical nature and in particular the requirements relating to movement of the operating parts connected thereto, by means of the use of a mechanical structure provided with a limited number of hinging points and mechanical components.
[0024] Another object of the present invention is that of providing a shovel arm provided with a mechanical structure of small dimensions able to allow good visibility from the operating cab of the vehicle.
[0025] A further object of the present invention is that of providing a shovel arm provided with a mechanical structure which is constructionally simple, easy to assemble, operationally entirely reliable and suitable for performing any manoeuvre within the limits of the operational requirements of the vehicles associated therewith.
[0026] These and still further objects are all achieved by the shovel arm in question, which comprises a support arm connected to the body of an earth-moving vehicle, by means of a first hinge, and to a working part, by means of a second hinge, a linear raising actuator mounted on the body of the vehicle, by means of a third hinge, and connected to the support arm, by means of a fourth hinge, and a linear operating actuator connected to the body of the earth-moving vehicle, by means of a fifth hinge, and to a lever, by means of a sixth hinge. This lever is also connected to the support arm and to the linear raising actuator by means of the abovementioned fourth hinge. A connecting rod is also provided, being connected to the working part, by means of a seventh hinge, and jointly to the linear operating actuator and to the lever by means of the abovementioned sixth hinge. In accordance with a further characteristic feature of the invention, the arm occupies a small volume so as not to adversely affect the visibility from the operating cab of the vehicle.
[0027] The technical features of the invention, in accordance with the abovementioned objects, may be clearly determined from the contents of the claims indicated below and the advantages thereof will emerge more clearly from the detailed description which follows, with reference to the accompanying drawings which show a purely non-limiting example of embodiment thereof, in which:
- Figure 1 shows schematically a side view of the improved shovel arm according to the present invention in two different operating positions, i.e. a lowered position and raised position, respectively;
- Figure 2 shows schematically a side view of the shovel arm according to Fig. 1 mounted on an earth-moving vehicle;
- Figure 3 shows schematically a top plan view of the shovel arm according to Fig. 2.
[0028] In accordance with the figures of the accompanying drawings, 1 denotes in its entirety the shovel arm according to the present invention.
[0029] As can be seen, the shovel arm 1 in reality consists of two side-pieces which are identical to each other and connected by a front cross-piece. Below, for the sake of simplicity of illustration, the term shovel arm 1 will be used to indicate one of these two side-pieces.
[0030] The arm 1 is connected at one of its ends 2 to the front part of an earth-moving vehicle 3 and supports, at the other end 4, a working part consisting in the case of the example according to Fig. 2 of a bucket 5.
[0031] The connection of the shovel arm 1 to the body of the vehicle 3 is performed by means of two linear actuators, namely a raising actuator 6 and an operating actuator 7, consisting preferably of two hydraulic jacks, and a support arm 8 to which the bucket 5 is directly connected.
[0032] Operationally speaking, the raising bucket 6 is used to perform raising and lowering manoeuvres of the shovel arm 1 and therefore of the bucket 5 connected thereto.
[0033] The latter may also be actuated by the operating jack 7 via a transmission mechanism 9 described in detail below, so as to perform the programmed working manoeuvres in accordance with all the possible operational requirements of the earth-moving vehicle.
[0034] In other words, as a result of actuation of the operating jack 7, the bucket 5 is able to rotate about an axis Y transverse with respect to the shovel arm 1 and thereby remove the material, for example, from the ground, loading it inside the bucket 5 itself.
[0035] Structurally speaking, the shovel arm 1 according to the present invention has a plurality of mechanical components (the body of the vehicle 3, the two hydraulic jacks, i.e. the raising jack 6 and operating jack 7, the support arm 8, the transmission mechanism 9 and the bucket 5) which are connected together so as to form a single mechanical structure provided with connections for interlinking its components, which are described hereinbelow.
[0036] The support arm 8 is connected at one end 10 to the body of the vehicle 3 by means of a first hinge 11, and at its other end 12 to the bucket 5 by means of a second hinge 13.
[0037] The raising jack 6 is in turn connected to the body of the vehicle 3 by means of a third hinge 14 arranged in a lower position than the first hinge 11. At the other end it is connected to the central arm 8 in the region of a central zone 15 of the latter close to the bottom edge by means of a fourth hinge 16.
[0038] The operating jack 7 is also connected at one end to the body of the vehicle 3 by means of a fifth hinge 17 and at the other end to a first end 18 of a lever 19 by means of a sixth hinge 20. The fifth hinge 17 therefore represents the third hinging point of the shovel arm 1 with the body of the vehicle 3 and is arranged at a greater height than the first hinge 11 and the third hinge 14.
[0039] The lever 19 is also connected at its second end 21 both to the support arm 8 and to the raising jack 6 by means of the fourth hinge 16.
[0040] The transmission mechanism 9 mentioned above comprises, in addition to the lever 19, also a connecting rod 22 which is connected at its first end 23 to the bucket 5 by means of a seventh hinge 24 and connected at the second end 25 both to the operating jack 7 and to the first end 18 of the lever 19 by means of the sixth hinge 20.
[0041] Therefore, on the basis of the geometry defined by the mechanical structure described, the bucket 5 is connected to the shovel arm 1 by means of the two hinges 13 and 24 and is able to perform rotations about the axis Y passing through the second hinge 13, when the operating jack 7 is actuated so as to extend (for example in order to empty a load from the bucket 5) or retract (for example in order to allow the bucket 5 to load material inside it). The two extending and retracting movements of the operating jack 7 cause rotations of the bucket 5 which correspond to rotations of the shovel arm 1 during lowering and during raising thereof, respectively.
[0042] With reference to Fig. 1, two different operating positions of the shovel arm 1 have been illustrated, namely a fully raised position, indicated by 26, and fully lowered position, indicated by 27.
[0043] Taking as reference points for determining the inclination of the bucket 5 a horizontal plane P passing through the second hinge 13 and an axis R joining the two points where the shovel arm 1 is hinged with the bucket 5 (namely the second hinge 13 and the seventh hinge 24), it is possible to define an angle A indicating the angular position of the bucket 5 with respect to the shovel arm 1.
[0044] Advantageously, following movement of the shovel arm 1 from the fully lowered position 26 to the position fully extended forwards (not shown in the accompanying figures and substantially corresponding to an intermediate position of the shovel arm 1 between the two end positions 26 and 27 indicated), the bucket 5 varies its inclination with respect to the horizontal plane P, rotating through an angle of between about 1 and 10 degrees and therefore correspondingly reducing the angle A by an equivalent value.
[0045] As is known, in fact, when the shovel arm 1 of an earth-moving vehicle is arranged in a substantially intermediate position between the fully raised position and the fully lowered position (such as those illustrated in Fig. 1), it exerts a high force (maximum moment) with respect to its connection to the vehicle body. Especially when there are heavy loads carried by the bucket 5, forwards tipping of the vehicle through a few degrees may occur.
[0046] This is principally due to the resilient deformation of the tyres of the vehicle itself which cause precisely slight tipping at the front with consequent slight lowering of the shovel arm.
[0047] In order to overcome this drawback, the mechanical structure of the shovel arm 1 described here is provided with a system for automatic compensation of these tipping movements, causing rotation of the bucket 5 with respect to the horizontal plane P through an angle of between about 1 and 10 degrees (rotation in a clockwise direction in Fig. 1).
[0048] Similarly, it is also envisaged, following movement of the shovel arm 1 between the fully lowered position 26 and the fully raised position 27, that the bucket 5 is able to rotate with respect to the horizontal plane P through an angle of between about 10 and 20 degrees, therefore correspondingly varying the angle A by an equivalent value (rotation again in the clockwise direction in Fig. 1). This rotation, resulting from the geometry of the mechanical structure which makes up the shovel arm 1 in question, is not operational disadvantageous for operative purposes and instead allows the abovementioned compensation of forwards tipping of the vehicle 3 to be achieved when the arm 1 is in the fully extended (i.e. forwards) position.
[0049] It should also be noted that, in accordance with that described above, the movement of the shovel arm 1 is achieved by means of a limited number of hinges and a limited number of mechanical components, Consequently the entire structure of the arm has overall dimensions which are fairly small and certainly smaller than those of the corresponding conventional arms.
[0050] In this way the visibility from the operating cab 50 is improved compared to that which is permitted by the structures used hitherto on earth-moving vehicles. This allows an operator who is performing manoeuvres to view more easily the operating movements of the bucket 5 from the operating cab 50 also under more difficult operating conditions. In order to further improve the visibility of the bucket 5 for the operator, a special lower design (see Fig. 3) has been developed for the front bonnet 51 of the vehicle 3 and the front windscreen 54 of the operating cab 50 which, as can be seen in Fig. 3, also extends along a part 52 of the roof 53 of the operating cab 50. This allows the visibility of bucket 5 to be improved, in particular when the arm 1 is arranged in the fully raised position 27, while complying with the safety regulations.
1. Improved shovel arm for earth-moving vehicles comprising: a support arm (8) connected
at one of its ends (10) to the body of an earth-moving vehicle (3) by means of a first
hinge (11) and at the other end (12) to a working part (5) by means of a second hinge
(13); a raising actuator (6) mounted on said body of the vehicle (3) by means of a
third hinge (14) and connected to said support arm (8) by means of a fourth hinge
(16) substantially for performing the raising and lowering movement of the shovel
arm (1); an operating actuator (7) also able to move said working part (5) in accordance
with programmed operational requirements by means of a transmission mechanism (9)
designed to perform a mechanical connection between said working part (5) and said
body of the vehicle (3), characterized in that said operating actuator (7) is connected
at one of its ends to said body of the vehicle (3) by means of a fifth hinge (17)
and at the other end to a first end (18) of a lever (19) by means of a sixth hinge
(20), said lever (19) being in turn connected, at its second end (21), to said support
arm (8) and to said raising actuator (6) by means of said fourth hinge (16), said
transmission mechanism (9) comprising a connecting rod (22) connected at its first
end (23) to said working part (5) by means of a seventh hinge (24) and connected at
its second end (25) to said operating actuator (7) and to said first end (18) of said
lever (19) by means of said sixth hinge (20), said raising actuator (6) and operating
actuator (7), said support arm (8), said lever (19) and said connecting rod (22) thus
occupying a small volume so as not to limit the visibility of the working part (5)
from the operating cab (50) of the vehicle (3).
2. Shovel arm according to Claim 1, characterized in that said first hinge (11) is arranged
at a height lying between the height of said fifth hinge (17) and the height of said
third hinge (14).
3. Shovel arm according to Claim 1, characterized in that said working part (5), as a
result of the movement of the shovel arm (1) between said fully lowered position (26)
and said fully raised position (27), varies its inclination, defined by means of an
angle (A) comprised between a horizontal plane (P) passing through said second hinge
(13) and an axis (R) geometrically joining said second hinge (13) and said seventh
hinge (24), by a value of between about 10 and 20 degrees.
4. Shovel arm according to Claim 3, characterized in that said working part (5) varies
said inclination by an angle value of between 1 and 10 degrees following the movement
of the shovel arm (1) from the fully lowered position (26) to the fully extended position
forwards with respect to the earth-moving vehicle (3), in order to compensate angularly
for possible tipping movements of the vehicle (3) itself.
5. Shovel arm according to Claim 1, characterized in that said fourth hinge (16) is formed
substantially in a central zone (15) of the bottom edge of said support arm (8).
6. Shovel arm according to Claim 3, characterized in that said working part (5) causes
variation of said angle (A) during movement of the shovel arm (1) between said fully
lowered position (26) and said fully raised position (27) in the same direction as
rotation of the shovel arm (1).
7. Shovel arm according to Claim 1, characterized in that the operating cab (50) is provided
with a front windscreen (54) which extends over a part (52) of the roof (53) of the
operating cab (50) in order to improve the visibility of the working part (5) from
the operating cab itself (50).
8. Shovel arm according to Claim 1, characterized in that said lever (19) is connected
exclusively to said hinges (16) and (20).