EP3286126B1 - Arm assembly of the scissor-type for a scissor-type lifting mechanism of a lifting platform - Google Patents

Description

The present invention relates to the field of mobile elevating work platforms (also referred to as PEMP) still commonly referred to as aerial work platforms. It relates more particularly to scissor lifts.

Scissor lifts are machines designed to allow one or more people to work at height. They include a frame, a work platform and a lifting mechanism of the work platform. The chassis is mounted on wheels to allow movement of the aerial platform to the ground. The work platform includes a tray surrounded by a railing. It is intended to accommodate one or more people and possibly also loads such as tools or other material, materials such as paint, cement, etc ... The working platform is supported by the lifting mechanism which is mounted on the chassis. The lifting mechanism lifts the work platform from a lowered position on the frame to the desired working height, usually by means of one or more hydraulic cylinders. Depending on the models concerned, the maximum working height generally varies between 6 and 18 meters.

The Figures 1 and 2 illustrate such a lifting platform of the prior art which is marketed by the applicant in its range called Optimum: the frame is referenced 1, the scissor lift mechanism 2, the work platform 3, the hydraulic cylinder of actuation of the lifting mechanism of the work platform 4.

As can be seen in the enlarged view of the figure 3 , the scissor lift mechanism comprises pairs of tubular beams hinged together at their center in the manner of scissors, a plurality of such scissors being mounted one above the other by their ends hinged together: cf. the four pairs (21, 22), (23, 24), (25, 26) and (27, 28). These four pairs of stacked scissors constitute a first set of stacked scissors. As is the most common case, the scissor mechanism comprises a second set of stacked scissors which is identical to the first set and parallel thereto while being offset laterally with respect to the first: cf. the four pairs (31, 32), (33, 34), (35, 36) and (37, 38). The use of two sets of parallel scissors ensures the horizontal stability of the work platform. We are talking about double scissor lift in this case. In this case, the lifting mechanism 2 comprises 4 stages of scissors indicated by the references 11 to 14, but there may be more or less. Scissor beams are also commonly referred to as scissor arms.

The hydraulic cylinder 4 is mounted at both ends to the sets of scissors, each to another stage of scissors. In this way, the cylinder can open and close the scissors to raise and lower the work platform. For other aerial platforms of the prior art, one of the ends of the hydraulic cylinder 4 is mounted on the chassis of the aerial platform. In order to allow the opening and closing of the scissors, the lower ends of two homologous beams of the first stage 11 are pivotally mounted on the frame 1 by an axis 15 while the lower ends of the two other homologous beams of the same stage are traversed by an axle 16 which is slidably mounted on the frame 1. Similarly, the upper ends of two homologous beams of the last stage 14 are pivotally mounted under the working platform 3 by an axis 17 while the lower ends of the two other homologous beams of the same floor are traversed by an axis 18 which is slidably mounted under the working platform 3.

To provide overall rigidity to the lifting mechanism and avoid deformations of the two sets of scissors in the lateral direction of the aerial platform, the latter are interconnected generally on all floors. More specifically, the inner beams of the same scissor stage are rigidly interconnected by spacers so as to form a one-piece assembly. The figure 4 illustrates the case of the inner beams 24 and 34 of the second scissors stage 12 which are interconnected by a respective spacer 40, 41 at each end. A third spacer connecting the inner beams is arranged in their center for the other scissors stages 11, 13 and 14, because it does not interfere with the cylinder 4. As can be seen on the figure 5 these spacers are mounted in holes in the inner beams. More specifically, the spacers pass through the inner beams and are welded to each side of the inner beams.

Furthermore, these spacers have a cylindrical section and serve as a mounting housing at each end for a respective pivot axis 42, 43 for the corresponding inner and outer arms 24, 25 and 34, 35. The pivot axes 42, 43 are blocked in the spacer by a respective bolt 44, 45. The outer beams 25, 35 each comprise a through hole in which is housed a bushing 50, respectively 51. The bushes 50, 51 are welded on each side to the outer beam corresponding 25, respectively 35. The bushings 50, 51 define the mounting housing pivot axes 42, 43 respectively. For this, the bushes 50, 51 are each provided with a plain bearing ring 52, 53 respectively. A respective elastic ring 54, 55 blocks the sliding of the outer arms 25, 35 on the corresponding pivot axis 42, 43.

There are other scissor lifts in the market in which the connecting struts of the inner beams of the scissor lift mechanism do not receive the pivot axes of the inner and outer beams. In this case, the spacers are welded to the inner beams at a location offset from the pivot axis of the beams. The latter are each received in the internal beams by means of a socket fixed in a passage hole similarly to the case of the outer arms.

The manufacture of such a lifting mechanism is in practice difficult and expensive. Indeed, the passages of the pivot axes in the inner and outer beams must be arranged accurately, especially since the positioning defects are passed from one scissor stage to another. Otherwise, the lifting mechanism may be subject to premature fatigue. However, welding operations both sockets in the scissor beams and connecting struts in or on the inner beams, depending on whether they serve as a housing pivot axes or not, lead to deformations of the beams and sets monobloc constituted by the inner arms of each scissors stage. These deformations lead to relative positioning errors of the pivot axis housings which must be kept to a minimum. In addition, the weld seams at the boss of the sleeves or spacers passing through the beams can be the seat of significant stress concentrations that limit their fatigue life. Therefore, it is generally necessary to resume, once the welding operations have been completed, the bores of the bushings welded in the beams and, where appropriate, those of the spacers welded in the inner beams at their two ends serving to accommodate the pins. pivoting in order to control the level of mechanical stresses in the axes and in the weld seams of the sleeves and spacers on the beams. In the case of spacers, the machining is even more complicated because of the size of the one-piece assembly constituted by the inner beams connected together.

As regards the mounting, in the scissor beams, bushings housing the pivot axes, US 2008/0105498 A1 proposes to replace the welding by a plastic deformation operation of the ends of the sleeve after mounting in the passage hole of the beam to keep it in place in the beam. This solution can pose difficulties in terms of the precision of the parts. In addition, it requires placing a spacer in the beam through which the sleeve is received, which makes more complex the manufacture of the scissor beam. It is also necessary to make an opening in the tubular beam to introduce the spacer, which weakens the beam. Alternatively, it is necessary to use beams with a U-shaped profile which have less mechanical strength than the tubular beams.

Moreover, it is known to US 5,113,972 A a scissor arm assembly of a scissor lift mechanism of the work platform of an aerial work platform, comprising two scissor arms pivotally mounted together about an axis extending through both arms. Each arm is formed by a tubular beam. The tubular beam of one of the arms has a local reinforcing plate welded to the outer surface of one side of the beam facing the other arm. This first arm has a first hole for the passage of the axis formed in the reinforcing plate and the corresponding side of the beam, and a second hole for the passage of the axis formed in the opposite side of the beam. The axis is circumferentially supported in the first through hole by both the beam and the backing plate and in the second through hole only through the beam. The axis is free of support inside the beam between the two through holes and is welded to the outer surface of the beam around the second through hole. The second arm has two holes formed in two opposite sides of the tubular beam in which is mounted a same sleeve which receives the axis.

The object of the present invention is to at least partially overcome the aforementioned drawbacks.

• chacun des bras est formé par une poutre tubulaire laquelle présente :
  • ∘ une première plaque de renfort locale soudée sur la surface extérieure d'un premier côté de la poutre ; et
  • ∘ une deuxième plaque de renfort locale soudée sur la surface extérieure d'un deuxième côté de la poutre qui est opposé au premier côté de la poutre ;
• chacun des bras présente :
  • ∘ un premier trou de passage de l'axe réalisé dans la première plaque de renfort et le premier côté de la poutre, et
  • ∘ un deuxième trou de passage de l'axe réalisé dans la deuxième plaque de renfort et le deuxième côté de la poutre ;
  dans lequel :
  • ∘ l'axe est supporté circonférentiellement dans le premier trou de passage à la fois par la poutre et la première plaque de renfort ;
  • ∘ l'axe est supporté circonférentiellement dans le deuxième trou de passage à la fois par la poutre et la deuxième plaque de renfort ; et
  • ∘ l'axe est libre de support à l'intérieur de la poutre entre le premier trou de passage et le deuxième trou de passage.

To this end, the present invention proposes, in a first aspect, a scissor arm assembly for a scissor lift mechanism of the work platform of an aerial work platform, comprising a first scissor arm and a second scissor arm. scissors mounted together pivotably about an axis traversing the two arms, wherein:

• each of the arms is formed by a tubular beam which presents:
  • A first local reinforcing plate welded to the outer surface of a first side of the beam; and
  • A second local reinforcing plate welded to the outer surface of a second side of the beam which is opposite to the first side of the beam;
• each of the arms presents:
  • A first hole for passing the pin made in the first reinforcing plate and the first side of the beam, and
  • A second hole for passage of the axis made in the second reinforcing plate and the second side of the beam;
  in which :
  • The axis is supported circumferentially in the first through hole by both the beam and the first reinforcing plate;
  • The axis is supported circumferentially in the second through hole both by the beam and the second reinforcing plate; and
  • ∘ the axis is free of support inside the beam between the first through hole and the second through hole.

It is indeed unnecessary for the pivot axis to be supported over the entire width of the scissor beam as is generally the case in the prior art. It will be understood that those skilled in the art will dimension the reinforcing plates, in particular their thickness, so that the width of the through holes is appropriate to properly support the pivot axis which is received with respect to the mechanical stresses. to which they will be subjected within the aerial platform.

This way of achieving the assembly of the scissor arms avoids the use of housing parts of the pivot pins which pass right through the scissor beams and which are welded to them on each side. In other words, it eliminates the need, as was the case in the prior art, for housing bushings in scissor beams and welded on both sides thereof, and in the case of double scissor lifts, to penetrate and traverse the scissor beams by welding them into on both sides of the connecting struts of the inner arms. Since the shape and size of the reinforcing plates are not directly imposed by those of the pivot axis or a part receiving the axis as is the case of the sleeve or spacer in the Prior art, these may be chosen by those skilled in the art so as to limit the stress concentrations in the weld bead that binds them to the beams to improve its fatigue life. From this point of view, the length of the weld bead - which is determined by the perimeter of the reinforcing plates - may advantageously be chosen greater than that of the weld bead usually applied at the boss of the sleeves or spacers passing through the beam. in the case of the prior art. Moreover, unlike US 2008/0105498 A1 the solution of the invention makes it possible to use a tubular beam without having to weaken it with openings.

The two holes for passage of the axis can advantageously be made - or finished in case of pre-drilling - after the welding operation of the reinforcing plates. In this way, the possible deformations of the beam due to welding will not influence the positioning of the through holes. Furthermore, the machining operations of the through holes are minimized because the cumulative depth of the two axis passage holes is less than the width of the scissor beam unlike the case of bushings or spacers in the prior art.

Of course, how to achieve the assembly of the scissor arms according to the invention can be used for each of the pivotal connections between an arm and other arms. It is advantageous for all pivotal connections between one arm and other arms to be made in this way.

In the case of scissor lift aerial work platforms, it is particularly advantageous to combine the assembly of the scissor arms according to the invention with a rigid connection solution of the inner beams without welding. It can nevertheless also be used with its own advantages in the case where the spacers are welded to the internal beams at off-axis locations. In this case, the machining of the passage holes of the pivot axes in the inner arms is preferably performed after the welding of the spacers.

It will be understood that the assembly of the scissor arms according to the invention can also be used for single scissor lifts, that is to say which comprise only one set of stacked scissors.

• l'axe est bloqué en translation par rapport aux deux bras ;
• l'axe est bloqué en rotation par rapport au premier bras ;
• une bague de palier lisse respective est agencée dans le premier trou de passage et dans le deuxième trou de passage du deuxième bras ;
• un élément d'arrêt est fixé de manière amovible au premier bras et interfère avec l'axe par coopération de forme pour arrêter la translation de l'axe par rapport au premier bras ;
• l'élément d'arrêt interfère avec l'axe par coopération de forme pour bloquer l'axe également en rotation par rapport au premier bras ;
• l'axe présente au moins une rainure engagée par l'élément d'arrêt pour bloquer l'axe à la fois en translation et en rotation par rapport au premier bras ;
• l'élément d'arrêt est fixé au premier bras par des vis ;
• l'élément d'arrêt est en forme de plaque ;
• l'assemblage comprend une plaque de montage pour un actionneur du mécanisme de levage en ciseaux, la plaque de montage étant montée au premier bras ;
• une extrémité de la plaque de montage est montée au premier bras par le biais de l'axe, la plaque de montage étant montée sur l'axe et prise en sandwich entre l'élément d'arrêt et le premier bras ;
• l'assemblage comprend au moins un deuxième axe par le biais duquel une extrémité de la plaque de montage est montée au premier bras et dans lequel :
  • ∘ la poutre formant le premier bras présente :
    • une troisième plaque de renfort locale soudée sur la surface extérieure du premier côté de la poutre ;
    • une quatrième plaque de renfort locale soudée sur la surface extérieure du deuxième côté de la poutre ;
    • un premier trou de passage du deuxième axe réalisé dans la troisième plaque de renfort et le premier côté de la poutre et dans lequel le deuxième axe est supporté circonférentiellement à la fois par la poutre et la troisième plaque de renfort ; et
    • un deuxième trou de passage du deuxième axe réalisé dans la quatrième plaque de renfort et le deuxième côté de la poutre et dans lequel le deuxième axe est supporté circonférentiellement à la fois par la poutre et la quatrième plaque de renfort ; et
  • ∘ la plaque de montage est montée sur le deuxième axe et pris en sandwich entre le premier bras et un deuxième élément d'arrêt fixé de manière amovible au premier bras, le deuxième élément d'arrêt interférant avec le deuxième axe par coopération de forme pour bloquer la translation du deuxième axe par rapport au premier bras ;
• le deuxième élément d'arrêt est identique au premier élément d'arrêt ;
• l'assemblage comprend deux autres bras de ciseaux montés ensemble de manière pivotante autour de l'axe, les deux autres bras étant distant axialement des premier et deuxième bras, les deux autres bras de ciseaux étant identiques aux premier et deuxième bras de ciseaux et maintenus sur l'axe de la même manière que les premier et deuxième bras de ciseaux.

According to preferred embodiments, the scissor arm assembly according to this first aspect of the invention comprises one or more of the following features:

• the axis is locked in translation relative to the two arms;
• the axis is locked in rotation relative to the first arm;
• a respective plain bearing ring is arranged in the first through hole and in the second through hole of the second arm;
• a stop member is removably attached to the first arm and interferes with the axis by shape cooperation to stop translation of the shaft relative to the first arm;
• the stop member interferes with the axis by shape cooperation to lock the axis also in rotation relative to the first arm;
• the axis has at least one groove engaged by the stop element to block the axis both in translation and in rotation with respect to the first arm;
• the stop element is fixed to the first arm by screws;
• the stop member is plate-shaped;
• the assembly comprises a mounting plate for an actuator of the scissor lift mechanism, the mounting plate being mounted to the first arm;
• one end of the mounting plate is mounted to the first arm through the axis, the mounting plate being mounted on the axis and sandwiched between the stop member and the first arm;
• the assembly comprises at least a second axis through which one end of the mounting plate is mounted to the first arm and wherein:
  • ∘ the beam forming the first arm presents:
    • a third local reinforcing plate welded to the outer surface of the first side of the beam;
    • a fourth local reinforcing plate welded to the outer surface of the second side of the beam;
    • a first hole for passing the second axis made in the third reinforcing plate and the first side of the beam and wherein the second axis is supported circumferentially by both the beam and the third reinforcing plate; and
    • a second hole for passing the second axis made in the fourth reinforcing plate and the second side of the beam and wherein the second axis is supported circumferentially by both the beam and the fourth reinforcing plate; and
  • ∘ the mounting plate is mounted on the second axis and sandwiched between the first arm and a second stop member removably attached to the first arm, the second stop element interfering with the second axis by shape cooperation for block the translation of the second axis relative to the first arm;
• the second stop element is identical to the first stop element;
• the assembly comprises two further scissor arms pivotally mounted together about the axis, the other two arms being axially spaced from the first and second arms, the other two scissor arms being identical to the first and second scissor arms and held on the axis in the same way as the first and second scissor arms.

According to a second aspect, the invention proposes a lifting platform comprising a chassis, a work platform and a scissor lift mechanism mounted on the frame and supporting the work platform to move it upwards, in which the scissor lift mechanism comprises at least one scissor arm assembly according to the first aspect. It is advantageous that all the scissor arms at their different pivotal connection areas with the other scissor arms of the lifting mechanism and the manner of pivotably assembling them are made in accordance with the scissor arm assembly such as defined according to the first aspect of the invention.

• Les figures 1 et 2 représentent chacune une vue en perspective d'une même nacelle élévatrice à double ciseaux de l'art antérieur, sa plate-forme de travail étant respectivement en position abaissée et à l'état levé.
• La figure 3 est une vue en perspective du mécanisme de levage en ciseaux de la nacelle élévatrice des figures 1 et 2.
• La figure 4 est une vue en perspective de l'ensemble monobloc formé par les poutres intérieures du deuxième étage de ciseaux du mécanisme de levage de la figure 3.
• La figure 5 est une vue en coupe partielle de l'assemblage, à une extrémité, de l'ensemble monobloc de la figure 3 avec les poutres extérieures du troisième étage de ciseaux.
• La figure 6 est une vue en perspective du mécanisme de levage en ciseaux selon un mode de réalisation de l'invention qui est destiné à remplacer celui de la figure 3 pour la nacelle élévatrice des figures 1 et 2, celui-ci étant regardé d'un point de vue placé de l'autre côté du mécanisme de levage par rapport à la figure 3.
• La figure 7 est une vue en coupe partielle montrant l'assemblage de deux bras de ciseaux intérieurs du deuxième étage avec les deux bras extérieurs du troisième étage du mécanisme de levage de la figure 6.
• Les figures 8 et 9 représentent chacune une vue en perspective d'un bras de ciseaux intérieur du deuxième étage du mécanisme de levage de la figure 6, la première montrant le côté vers l'extérieur de la nacelle élévatrice et la deuxième montrant le côté vers l'intérieur de la nacelle élévatrice, c'est-à-dire le côté du bras qui fait face à l'autre ensemble de ciseaux empilés.
• La figure 10 est une vue en perspective d'une plaque d'arrêt utilisée dans l'assemblage illustré par la figure 7.
• La figure 11 est une vue en perspective d'un axe de pivotement de bras du mécanisme de levage de la figure 6.
• La figure 12 est une vue en coupe locale faite perpendiculairement à l'axe de pivotement au niveau de l'une des plaques d'arrêt de la partie de l'assemblage montrée à la figure 7.
• La figure 13 est une vue locale en perspective du mécanisme de levage de la figure 6 faite au niveau des plaques de montage d'une extrémité du vérin hydraulique d'actionnement.
• La figure 14 est une vue en perspective d'une des plaques de montage de vérin visible sur la figure 13.
• La figure 15 est une vue en coupe locale à travers les bras auxquels sont montés les plaques de montage du vérin de la figure 13.

Other aspects, characteristics and advantages of the invention will appear on reading the following description of a preferred embodiment of the invention, given by way of example and with reference to the appended drawing.

• The Figures 1 and 2 each represent a perspective view of the same double scissor lift platform of the prior art, its working platform being respectively in the lowered position and in the raised state.
• The figure 3 is a perspective view of the scissor lift mechanism of the aerial lift Figures 1 and 2 .
• The figure 4 is a perspective view of the one-piece assembly formed by the internal beams of the second scissor stage of the lifting mechanism of the figure 3 .
• The figure 5 is a partial sectional view of the assembly, at one end, of the monobloc assembly of the figure 3 with the external beams of the third floor of scissors.
• The figure 6 is a perspective view of the scissor lift mechanism according to one embodiment of the invention which is intended to replace that of the figure 3 for the aerial lift Figures 1 and 2 , the latter being viewed from a point of view placed on the other side of the lifting mechanism with respect to the figure 3 .
• The figure 7 is a partial sectional view showing the assembly of two inner scissors arms of the second stage with the two outer arms of the third stage of the lifting mechanism of the figure 6 .
• The Figures 8 and 9 each represent a perspective view of an inner scissor arm of the second stage of the lifting mechanism of the figure 6 , the first showing the outward side of the aerial work platform and the second showing the inward side of the aerial platform, ie the side of the arm facing the other set of scissors stacked.
• The figure 10 is a perspective view of a stop plate used in the assembly illustrated by the figure 7 .
• The figure 11 is a perspective view of an arm pivot axis of the lifting mechanism of the figure 6 .
• The figure 12 is a local sectional view taken perpendicular to the pivot axis at one of the stop plates of the part of the assembly shown in FIG. figure 7 .
• The figure 13 is a local perspective view of the lifting mechanism of the figure 6 made at the mounting plates of one end of the hydraulic actuating cylinder.
• The figure 14 is a perspective view of one of the jack mounting plates visible on the figure 13 .
• The figure 15 is a sectional view through the arms to which are mounted the cylinder mounting plates of the figure 13 .

We will describe below a preferred embodiment of the invention with reference to Figures 6 to 15 .

The figure 6 shows an overview of the scissor lift mechanism which is intended to replace that of the prior art of the figure 3 in the aerial lift Figures 1 and 2 .

The general configuration of the lifting mechanism is similar to that of the figure 3 . Like this one, it includes two sets of scissors parallel and distant from each other. Each set of scissors comprises pairs of tubular beams hinged together in their center in the manner of scissors, a plurality of such scissors being mounted one above the other by their ends hinged together: cf. the four pairs (121, 122), (123, 124), (125, 126) and (127, 128) defining the first set of stacked scissors and the four pairs of scissors (131, 132), (133, 134) , (135, 136) and (137, 138) defining the second set of stacked scissors. The section of the tubular beams is preferably rectangular or square, but may be different. The lifting mechanism also includes 4 stages of scissors referenced from 11 to 14, but there may be more or less. It also includes the axes 15 and 16 mounted at the lower ends of the beams of the first stage 11 to be mounted on the frame 1 pivotally connected to the first and slidably connected to the second. In the same way, there are the axes 17 and 18 mounted at the upper ends of the beams of the last stage 14 to be mounted under the working platform 3 in pivotal connection for the first and in sliding connection for the second . There is also the hydraulic cylinder 4 for actuating the scissor mechanism which is mounted between the first and third scissor stages 11, 13. Alternatively, the cylinder 4 can be mounted between other scissor stages or between the chassis 1 and one of the scissor stages. It can also be provided several cylinders 4 instead of one, each can be mounted on different scissor stages.

In the following, we will describe the specificities of the lifting mechanism of the figure 6 .

With reference to Figures 7 to 12 , we will describe more particularly the structure of the scissor arms and how to assemble them pivotally between them, as well as the manner in which the two sets of parallel scissors are rigidly connected to each other.

The figure 7 shows the structure of the inner beam 124 and the outer beam 125 of the first set of scissors stacked at their pivotal connection, and how to assemble them. It is the same for the inner beam 134 and the outer beam 135 of the second set of stacked scissors. We will limit the description to the case of the beams 124, 125 because the structure of the beams 134, 135 and their pivoting assembly are identical. More generally, the structure of all the scissor beams at their different pivotal connection areas with the other scissor beams of the lifting mechanism and the manner of pivotally assembling them are preferably always the same. Therefore, the following description applies to any pivotal connection between any scissor beam with another scissor beam of the lifting mechanism, whether it is a connection in their central part or in their zone. end, any differences in implementation being mentioned where appropriate.

The Figures 8 and 9 show in isolation the beam 124 on both sides, it being specified that this description also applies to the beam 134. There are three pivot axis passages which traverse the beam 124 from one side to the other: one at each end for mounting in pivotal connection with the beams 121 and 125 and one which is central for mounting in pivotal connection with the beam 123. At each axis passage, a reinforcing plate is welded on each side of the beam 124 of preferably over the entire contour of the reinforcement plate: cf. the reinforcing plates 80 and 81 at each end axis passage of the beam 124 and the reinforcing plates 80A, 81A at the central axis passage of the beam 124. The reinforcing plates 81 are identical to the reinforcing plates 80, but they are crossed in addition by two threads - visible, but not referenced - which also cross the side of the beam 124 on which they are welded. These threads are intended to receive screws 95 visible on the figure 7 . The reinforcing plates 80A and 81A are identical to the reinforcing plates 80 and 81 respectively, except to note that the axis passage y is centered while the axis passage is off-center for the reinforcing plates 80 and 81 because of its arrangement towards the end of the beam. The threads are placed symmetrically on either side of the axis passage in the case of the plates 81 and 81A.

Each of the axis passages is made up of two axis passage holes 103, 104. The axis passage hole 103 is defined by the hole passing through the reinforcing plate 80, respectively 80A and the side wall. beam 124 on which it is welded. Similarly, the axis passage hole 104 is defined by the through hole together the reinforcing plate 81, respectively 81A and the side wall of the beam 124 on which it is welded.

With reference to the figure 7 the axis passage defined by the holes 103, 104 of the beam 124 is traversed by a pivot axis 70. The axis 70 is supported circumferentially in the first through hole 103 by both the reinforcing plate 80 and the wall of the beam 124 on which it is welded. Similarly, the axis 70 is circumferentially supported in the second through hole by both the reinforcing plate 104 and the wall of the beam 124 on which it is welded. Is visible on the figure 7 the fact that the axis passage of the beam 124 is free of socket or similar piece connecting the two opposite walls of the beam 124 unlike the case of the prior art. In other words, the scissors arm formed by the beam 124 with its reinforcing plates 80, 81 circumferentially supports the axis only by means of the two through holes 103, 104. Therefore, the skilled person will choose the thickness reinforcing plates 80, 81, respectively 80A, 81A, suitably for the pivot axis 70 to be supported satisfactorily by the two through-holes 103, 104.

The outer scissors arms formed by the beams 125, 135 are preferably identical to the inner ones 124, 134, with two exceptions that will be mentioned hereinafter.

The beams 125, 135 each have a reinforcing plate 82 welded to each side of the beam at the axis passage through which the axis 70 passes, but - first difference - there are no threads to receive screws 95.

The reinforcing plates 82 are preferably identical to the reinforcing plates 80. As for the beam 124, each of the axis passages consists of two axial passage holes 101, 102. All the considerations mentioned above concerning the circumferential support of the axis 70 in the axis passage holes 103, 104 are also valid for the axis passage holes 101, 102, unless specified - second difference with the beam 124 - that a plain bearing ring 83 respective is mounted in each axis passage hole 101, 102 to reduce friction with the axis 70. As is visible on the figure 7 , each smooth bearing ring 83 is stopped axially towards the inside of the beam 125 by a shoulder formed in the corresponding through-hole 101, 102. This difference is related to the fact that the beam 125 is free to pivot about the axis 70 while it is locked in rotation relative to the beam 124 as we shall see. Alternatively, the axis passage holes 101, 102 are free of plain bearings, but are machined and optionally surface treated or coated to form plain bearings. Locking the axis 70 in rotation with respect to the beam 124 avoids having to also arrange smooth bearings in the through holes 103, 104. Alternatively, the two beams 124, 125 are free to rotate relative to the axis 70.

A washer 100 is preferably mounted on the axis 70 between the beams 124 and 125 in order to limit the friction between them during their pivoting.

The axis 70 is locked in translation relative to the two beams 124, 125, and also with respect to the beams 134, 135. This can be achieved by any appropriate means, for example an elastic ring 85 on the side of the outer beam 125 and a shoulder on the axis 70 on the side of the inner beam 124.

But in the preferred case where the axis 70 is locked in rotation relative to the beam 124, it can advantageously be resorted to a stop member removably attached to the beam 124 and interfering with the axis 70 by cooperation of form to stop both translation and rotation of the axis 70 relative to the beam 124.

The stop member is preferably made in the form of a plate 90 illustrated in FIG. figure 10 . The stop plate 10 has a notch 92 having two parallel edges and two smooth holes 91. As can be seen on the figure 7 , the two smooth holes 91 serve to fix the stop plate 90 on the reinforcing plate 81 of the beam 124 by means of screws 95 screwed into the two tappings formed in the reinforcing plate 81 and the corresponding wall of the beam 124. The parallel edges of the notch 92 serve to engage two parallel and diametrically opposed grooves 71 formed in the axis 70 for this purpose: cf. the local cut perpendicular to the axis 70 at the two grooves 71 of the figure 12 . The stop plate 90 thus engages in the grooves 71 in the manner of a flat key. In this way, the stop plate 90 blocks both the axis 70 in translation and in rotation with respect to the beam 124. The figure 11 shows the axis 70 in perspective: it shows only one of the two grooves 71 for the connection of the axis 70 with the beam 124 due to the prospect. For the same reason, it also shows only one of the grooves 71 for the connection of the axis 70 with the beam 134. It also shows two grooves 72 which are not visible on the figure 7 because optional, but whose utility will be seen later. There is still a groove 73 at each end to receive the corresponding elastic ring 85. It will be noted that the manufacture of the stop plates 90 and the realization of the grooves 71 - and also 72 if necessary - on the axis 70 are very simple. Alternatively, the axis 70 is provided with a single groove 71 with which the stop plate 90 cooperates instead of two diametrically opposed grooves 71 in which case the shape of the notch 92 of the stop plate is adapted in result. However, the embodiment with two grooves 71 diametrically opposed is preferable from the mechanical point of view.

Alternatively, such a stop member removably attached to the beam 124 and interfering with the axis 70 by shape cooperation is used to stop only the translation of the axis 70 relative to the beam 124 in the case where we do not want to block the rotation of one relative to the other. For example, it suffices to replace the grooves 71 by a circumferential groove formed in the axis 70 intended to be engaged by the edges of the notch 92 of the stop plate 90.

Alternatively, the stop element is permanently fixed on the beam 124, but it is preferable that it is fixed removably as this advantageously allows to disassemble the lifting mechanism in case of failure of an axis of pivoting or scissor arm to replace it.

Alternatively, the translation and rotation of the axis 70 with respect to the outer beam 125 is blocked instead of the inner beam 124, in which case the above-mentioned stop element can be provided on the side of the outer beam 125. to be removably attached.

It will be noted that the axis 70 makes it possible to rigidly connect the inner beams 124, 134 to each other, in view of the locking in translation of the axis 70 with respect to the internal beams 124, 134. The two sets of parallel scissors are therefore rigidly connected to each other without the use of spacers. This avoids any welds spacers scissor beams that tend to deform the beams. In addition, the result is a weight gain because a common axis has a material section smaller than that of a spacer.

In addition, the use of a stop element, including in the form of the stop plate 90, which has just been described can also be applied to a short axis of pivoting of scissor beams. that is, receiving only two scissor beams instead of four. This is the case for example of the axis of pivoting in the central part of the beams 123, 124 of the first set of scissors and the axis of pivoting in the central part of the beams 133, 134 of the second set of scissors because that an axis common to these four beams would interfere with the lifting cylinder 4. This is also the case in our example of the central pivoting axis of the beams 125, 126 and the central pivoting axis of the beams 135, 136 as we see distinctly on the figure 13 .

Furthermore, the passages for the axes 15 and 16 in the lower ends of the scissor arms of the first stage 11, and those for the axes 17 and 18 in the upper ends of the scissor arms of the last stage 1 may advantageously be made of the same way as the passages of the axes of pivoting of the beams between them. These axes 15 to 18 can advantageously be maintained in the scissor arms by means of stop elements interfering with these axes in the same manner as described for the axes of pivoting of the scissor arms together, in particular by means of stop plates 90.

With reference to Figures 13 to 15 , we describe the mounting of one end of the actuating cylinder 4, in this case its rod, the inner beams of scissors third stage 13, it being specified that the other end of the cylinder is preferably mounted in the same way to the inner beams of scissors on the first floor 11.

The cylinder rod 4 is mounted to each of the inner scissor beams 126, 136 by means of a respective mounting plate 200 of generally triangular shape. Each mounting plate 200 is mounted in the same way to the scissor beam concerned. As a result, it will only be described for beam 126.

The figure 14 shows a mounting plate 200. It comprises a projection 201 forming a housing for receiving an end of an axis on which is articulated the end of the rod of the cylinder 4. It comprises at each end an axis passage hole 202 respectively 203, and two smooth holes 204, 205 respectively, made on either side of the axis passage hole.

As is visible on the Figures 13 and 15 one end of the mounting plate 200 is mounted on the end axis 70 pivotally connecting the scissor beams 123, 126 on the one hand and the scissor beams 133, 136 on the other hand. Since the pivotal assembly of these beams is identical - with one exception - to that described with reference to the Figures 7 to 12 , the same reference numbers have been used to designate identical elements. The only difference from the figure 7 is that the mounting plate 200 is further mounted on the axis 70 which passes through the through hole 203, the mounting plate 200 being sandwiched between the stop plate 90 and the reinforcing plate 81 of the beam 126. The screws 95 are screwed into the reinforcing plate 81 and the corresponding wall of the beam 126 through both the holes 91 of the stop plate 90 and the holes 205 of the mounting plate 200. material thickness of the mounting plate 200, the stop plate 90 engages the grooves 72 of the axis 70 provided for this purpose instead of the grooves 71. The grooves 72 are identical to the grooves 71 and serve for the same function - already described above - blocking the axis 70 relative to the inner beam of scissors through the stop plate 90. The grooves 72 are therefore only axially offset with respect to the grooves 71, as can be seen on the figure 11 , in order to take account of the material thickness of the mounting plate 200. Of course, the grooves 71 are not used in this case and could therefore be omitted from the axis 70.

The other end of the mounting plate 200 - which corresponds to the through hole 202 - is not mounted on a pivot axis of scissor beams because the mounting plate 200 does not extend to the axis of central pivoting scissor beams 125, 126. Such can obviously be the case and the mounting of this other end of the mounting plate on the central pivot axis would be in the same way as for the end corresponding to the hole passage 203 which has just been described.

In the case shown, the other end of the mounting plate 200 is mounted on a mounting axis 170 dedicated for this purpose alone. The axis 170 is received in an axis passage made in the beam 126 which is reinforced by a reinforcing plate 180, 181 welded on each side of the beam, in the same way as for the case of the pivot axis passages. scissor beams. These reinforcing plates are also preferably identical to the reinforcing plates 80A, 81A. The mounting plate 200 is mounted on the axis 170 which passes through the through hole 202. The holding of the mounting plate 200 against the beam 126 is ensured in the same way as at its other end, which is why the same reference numbers were used to designate identical elements. In other words, the mounting plate 200 is sandwiched between the reinforcing plate 181 of the beam 126 and a stop plate 90 screwed into the reinforcing plate 181 and the beam 126 by screws 95 passing through the holes 204 provided in FIG. this effect. This stop plate 90 also cooperates with grooves - similar to the grooves 72 of the axis 70 - formed in the axis 170 to block the translation of the axis 170 relative to the beam 126. As a result, the plate stop 90 also maintains the axis 170 in the beam 126.

Alternatively, both ends of the mounting plate may be mounted on a respective dedicated mounting shaft as described, but it is more advantageous to mount the jack mounting plates on at least one pivot axis of scissor beams. or two, for the sake of simplification of manufacture.

It will be understood that the different ways of mounting the mounting plate 200 to a scissors arm just described can also be used in the case of a single scissor lift to attach a support to a scissor arm. for mounting an end of the actuating cylinder of the scissor lift mechanism which comprises a plate identical or similar to the mounting plate 200.

Of course, the present invention is not limited to the embodiment and variants previously described and shown, but it is capable of many variants accessible to those skilled in the art.

It will also be understood that rigidly connecting together the two sets of parallel scissors - without the use of spacers - by means of pivot pins common to the scissor beams of the two sets of parallel scissors and stop elements. Interfering with the axes as described above, in particular in the form of stop plates 90, can be implemented independently of the structure of the pivot axis passages of the scissor beams according to the invention.

Claims (15)

1. An assembly of scissor arms for a scissor lifting mechanism of the work platform of an aerial work platform, comprising a first scissor arm (124) and a second scissor arm (125) mounted together pivotally around a shaft (70) crossing both arms, wherein:

   - each of the arms is formed with a tubular beam which has:

   ∘ a first local reinforcement plate (80; 82) welded on the outer surface of a first side of the beam; and

   ∘ a second local reinforcement plate (81; 82) welded on the outer surface of a second side of the beam which is opposite to the first side of the beam;

   - each of the arms has:

   ∘ a first shaft passage hole (101; 103) made in the first reinforcement plate and the first side of the beam, and

   ∘ a second shaft passage hole (102; 104) made in the second reinforcement plate and the second side of the beam;

   wherein:

   ∘ the shaft is circumferentially supported in the first passage hole both by the beam and the first reinforcement plate;

   ∘ the shaft is circumferentially supported in the second passage hole both by the beam and the second reinforcement plate; and

   ∘ the shaft is free of any support inside the beam between the first passage hole and the second passage hole.
2. The assembly according to claim 1, wherein the shaft is blocked in translation relatively to both arms.
3. The assembly according to claim 2, wherein the shaft is blocked in rotation relatively to the first arm (124).
4. The assembly according to claim 3, wherein a respective smooth bearing ring (83) is arranged in the first passage hole and in the second passage hole of the second arm (125).
5. The assembly according to any one of claims 2 to 4, comprising a stop element (90) attached removably to the first arm (124) and interfering with the shaft (70) by shape cooperation for stopping the translation of the shaft relatively to the first arm.
6. The assembly according to claim 5, wherein the stop element (90) interferes with the shaft by shape cooperation for also blocking the shaft (70) in rotation relatively to the first arm (124).
7. The assembly according to claim 6, wherein the shaft (70) has at least one groove (71) engaged by the stop element (90) for blocking the shaft (70) both in translation and in rotation relatively to the first arm (124).
8. The assembly according to any one of claims 5 to 7, wherein the stop element (90) is attached to the first arm with screws (95).
9. The assembly according to any one of claims 5 to 8, wherein the stop element has the shape of a plate (90).
10. The assembly according to any one of claims 5 to 9, comprising a mounting plate (200) for an actuator of the scissor lifting mechanism, the mounting plate being mounted to the first arm.
11. The assembly according to claim 10, wherein an end of the mounting plate (200) is mounted to the first arm (126) by means of the shaft (70), the mounting plate being mounted on the shaft and sandwiched between the stop element (90) and the first arm (126).
12. The assembly according to claim 10 or 11, comprising at least one second shaft (170) by means of which an end of the mounting plate is mounted to the first arm (126) and wherein:

    - the beam forming the first arm has:

    ∘ a third local reinforcement plate (180) welded on the outer surface of the first side of the beam;

    ∘ a fourth local reinforcement plate (181) welded on the outer surface of the second side of the beam;

    ∘ a first passage hole of the second shaft (170) made in the third reinforcement plate (180) and the first side of the beam and in which the second shaft is circumferentially supported both by the beam and the third reinforcement plate; and

    ∘ a second passage hole of the second shaft (170) made in the fourth reinforcement plate (180) and the second side of the beam and in which the second shaft is circumferentially supported both by the beam and the fourth reinforcement plate; and

    - the mounting plate (200) is mounted on the second shaft (170) and sandwiched between the first arm and a second stop element (90) removably attached to the first arm (126), the second stop element interfering with the second shaft by shape cooperation for blocking the translation of the second shaft (170) relatively to the first arm.
13. The assembly according to claim 12, wherein the second stop element is identical with the first stop element.
14. The assembly according to any one of claims 2 to 13, comprising two other scissor arms (134, 135) mounted together pivotally around the shaft (70), the two other arms being axially distant from the first and second arms (124, 125), the two other scissor arms being identical with the first and second scissor arms and maintained on the shaft (70) in the same way as the first and second scissor arms.
15. An aerial work platform, comprising a chassis (1), a work platform (3) and a scissor lifting mechanism (2) mounted on the chassis and supporting the work platform (3) for displacing it in height, wherein the scissor lifting mechanism comprises at least one assembly of scissor arms according to any one of claims 1 to 14.

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