AU2013369366B2

AU2013369366B2 - Weighing mechanism for a lift and aerial lift comprising said weighing mechanism

Info

Publication number: AU2013369366B2
Application number: AU2013369366A
Authority: AU
Inventors: Catherine COUZON; Sebastien Parot
Original assignee: Haulotte Group SA
Current assignee: Haulotte Group SA
Priority date: 2012-12-24
Filing date: 2013-12-23
Publication date: 2017-12-14
Anticipated expiration: 2033-12-23
Also published as: AU2013369366A1; CN104884914A; FR3000200A1; EP2936087A1; WO2014102240A1; CN104884914B; FR3000200B1; EP2936087B1

Abstract

This weighing mechanism for an aerial lift with a mast and a platform (7) comprises a force measuring cell (10) inserted between the mast and the platform (7). This mechanism comprises at least one first plate (30) provided with at least one first through orifice and at least one second plate (50) provided with at least one second through orifice. This mechanism also comprises at least one first slug and at least one second slug. Additionally, the cell (10) is provided with at least one first through housing and at least one second through housing. In the assembled configuration of the mechanism, the first slug is inserted into the first housing and the first orifice, and the second slug is inserted into the second housing and the second orifice.

Description

TITLE “Weighing Mechanism for a Lift and Aerial Lift Comprising said Weighing Mechanism”

Throughout this specification, unless the context requires otherwise, the word “comprise” and variations such as “comprises”, “comprising” and “comprised” are to be understood to imply the presence of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

TECHNICAL FIELD

The invention relates to a weighing mechanism for an aerial lift, and an aerial lift equipped with such a mechanism.

BACKGROUND

Any discussion of background art, any reference to a document and any reference to information that is known, which is contained in this specification, is provided only for the purpose of facilitating an understanding of the background art to the present invention, and is not an acknowledgement or admission that any of that material forms part of the common general knowledge in Australia or any other country as at the priority date of the application in relation to which this specification has been filed.

In the field of lifting loads or people, it is known and mandatory in Europe to use a load controller to block the operation of the lifting system in case of overload. The required precision is less than or equal to 20%. This value appears relatively easy to obtain, but in reality is not. One recurring issue in the field of lifting loads therefore remains the precision of the measurement of the vertical forces applied at the ends of a structure.

To offset this problem, it is known, for example from EP-A-1,630,124, to mount the platform of the lift on a deformable parallelogram with which a spring and contact system is associated making it possible to detect an overload. This is a system with two states that does not allow a proportional measurement of the weight. Furthermore, it has a risk seizing, which requires regular maintenance.

It is also known to measure the weight from a jack placed at the vertical between the arm and the chassis of a lift. The weight is calculated from the measurement of the pressure, the angle between the arm and the chassis and the length of the travel. This weighing mechanism provides a measurement sensitive to the temperature, the type of seals used and the adjustment of the machine. Furthermore, regular inspection and calibration are necessary.

It is also known to use a deformation load sensor fixed on an arm connected to the platform of a lift. The type of measurement provided in this case is very sensitive to the assembly quality between the sensor and the arm.

It is also known from EP-A-1,382,562 or DE-U-202 10 958 to use a weighing mechanism forming the connection between the arm of the lift on the one hand, and the platform of the lift on the other hand, while being fixed by screws that work by shearing. The measurement is sensitive to the tightening torque of the screws, and there is a risk of plastic deformation of the sensor. The quality of the measurement depends on the quality of the assembly.

The present invention described herein more particularly aims to resolve these drawbacks by proposing a weighing mechanism that is not very sensitive to the quality of the assembly, not requiring precise control of a tightening torque, and the mechanical strength of which does not depend on shearing forces on screwed elements.

SUMMARY OF INVENTION

In accordance with one aspect of the present invention, there is provided a weighing mechanism for an aerial lift that comprises a mast and a platform for supporting loads or people, the weighing mechanism comprising a force measuring cell inserted between the mast the platform, at least one first plate secured to a first support supported by the mast and defining a first bearing surface of the cell, said first plate being provided with at least one first through orifice, at least one second plate secured to a second support supporting the platform and defining a second bearing surface of the cell, said second plate being provided with at least one second through orifice, at least one first pin, and at least one second pin, wherein the cell is provided with at least one first through housing aligned with the first through orifice, and at least one second through housing aligned with the second through orifice, in an assembled configuration of the mechanism, and wherein, in the assembled configuration of the mechanism, the first pin is inserted into the first through housing and in the first through orifice, and the second pin is inserted in the second through housing and the second through orifice, and wherein, in a nominal usage configuration of the mechanism, each pin extends in a direction parallel to the weight of a mass supported by the platform.

Owing to the invention, described herein, the presence of the cell bearing on the surfaces of the plates and pins that pass through the cell makes it possible to have the cell work under good conditions, without risk of plastic deformation and without having to make fixing parts work by shearing. Thus, the vertical position of the pins through the housings and the through orifices makes it possible to improve the quality of the measurement of a load positioned on the platform.

According to advantageous but optional aspects of the invention, such a weighing mechanism may incorporate one or more of the following features, considered in any technically allowable combination: - the first plate and the second plate are each provided with two through orifices, the mechanism further comprises a third pin and a fourth pin, the cell is provided with two first through housings respectively aligned with the two first through orifices of the first plate and two second through housings respectively aligned with the two second through orifices of the second plate, in the assembled configuration of the mechanism, and whereas the first and third pins are inserted in the two first through housings of the cell and in the two first through orifices of the first plate and the second and fourth pins are inserted in the two second through housings of the cell and in the two second through orifices of the second plate, in the assembled configuration of the mechanism; - the mechanism comprises a third plate secured to the first support and defining a third bearing surface for the cell, said third plate being parallel to the first plate and defining, with the first plate and the first support, a first volume in which part of the cell can be inserted, the third plate being provided with at least one third through orifice, a fourth plate secured to the second support and defining a fourth bearing surface of the cell, the fourth plate being parallel to the second plate and defining, with the second plate and the second support, a second volume in which part of the cell can be inserted, the fourth plate being provided with at least one fourth through orifice, the first through housing is aligned with the third through orifice and the second through housing is aligned with the fourth through orifice, in the assembled configuration of the mechanism, and the first pin is inserted in the third through orifice and the second pin is inserted in the fourth through orifice, in the assembled configuration of the mechanism; - the third plate and the fourth plate are each provided with two through orifices, the two first housings of the cell are aligned with the two third through orifices of the third plate and the two second through housings of the cell are aligned with the two fourth through orifices of the fourth plate in the assembled configuration of the mechanism, and the first and third pins are inserted in the two third through orifices of the third plate and the second and fourth pins are inserted in the two fourth through orifices of the fourth plate in the assembled configuration of the mechanism; - a pin is immobilized relative to a plate through which it crosses using a screwed connection; - an inner thread is arranged in a plate near its through orifice and the pin is equipped with a member for stopping axial translation able to be screwed in the inner thread of the plate; - this stop member advantageously comprises a screw mounted on a tab secured to the pin and which extends radially relative to a central and longitudinal axis of the pin; - a pin is provided with at least one terminal thread on which a nut is tightened opposite the cell relative to the adjacent plate, in the assembled configuration of the mechanism; - the force measuring cell comprises a force sensor; - the force sensor is of the strain gauge type.

In accordance with another aspect of the present invention, there is provided an aerial lift comprising a chassis equipped with means for moving on the surface of the ground, a platform for supporting loads or people, a mast and means for elevating the platform relative to the chassis, wherein the aerial lift also comprises a weighing mechanism, as described above, connecting the platform and the mast.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood, and other advantages thereof will appear more clearly, in light of the following description of two embodiments of a weighing mechanism and an aerial lift according to its principle, provided solely as an example and done in reference to the appended drawings, in which: - figure 1 is an elevation block diagram of a lift according to a first embodiment of the invention; - figure 2 is an exploded perspective view of a weighing mechanism providing the connection between the platform and the arm of the lift of figure 1; - figure 3 is an enlarged partial view, with the ghost of a yoke joint, of detail III of figure 2; - figure 4 is a side view of a weighing mechanism in the assembled configuration, according to a second embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

The lift 1 shown in figure 1 is equipped with a chassis 2 resting on the surface of the ground S using four wheels, two of which are visible in this figure with references 3a and 3b. The chassis 2 bears a motor means 4 and a tower 5 that can rotate around an axis Z perpendicular to the surface of the ground S. The tower 5 in turn bears a mast 6 comprising a hub 61 as well as a part 62 telescoping relative to the hub 61. The possibility of extension of the mast 6 is shown by the double arrow F6 in figure 1. Alternatively, the mast could have more than one telescoping part.

In the upper part 6a of the mast 6, a pendular arm 63 that is part of the mast 6 is articulated and supports, by means of a weighing mechanism 100, a platform 7 on which one or more operators can stand or, alternatively, one or more loads.

The weighing mechanism 100 comprises two supports 8 and 9 and a force measuring cell 10.

The support 8 comprises a yoke joint 82 mounted by bolts 84 on a shaft 64 fastened to the end of the pendular arms 63 opposite the part 62. The yoke joint 82 is formed by a flat bottom 822 and two wings 824 and 826 perpendicular to the bottom 822 and between which the shaft 64 is received. Opposite the wings 824 and 826, the body 822 bears two parallel plates 20 and 30 that are welded on the bottom 822 and which define, between them and with the body 822, a first volume V1 in which part of the force measuring cell 10 can be inserted, in the assembled configuration of the mechanism 100.

The support 9 comprises a panel 92 welded on the floor 72 and on the railing 74 of the platform 7. Two plates 40 and 50 are welded on the face of the panel 92 opposite the railing. These plates 40 and 50 are parallel and define, between them and with the panel 92, a second volume V2 in which part of the force measuring cell 10 can be inserted, in the assembled configuration of the mechanism.

When the force measuring cell 10 is partially engaged in volumes V1 and V2, it bears against the plates 20, 30, 40 and 50. Thus, the surfaces 22, 32, 42 and 52 of the plates 20, 30, 40 and 50, turned toward the adjacent plate and which respectively define the volumes V1 and V2, constitute bearing surfaces for the cell 10. The surfaces 22 and 42 are not directly visible in figure 3, but identified by their edges.

The force measuring cell 10 comprises a housing 10A and a force sensor 10B, of the strain gauge type. The operation of the strain gauge sensors is based on the electric resistance variation of the gauge, proportionally to its deformation. Other types of sensors can be considered.

Each plate 20, 30, 40 or 50 is provided with two through orifices. References 21a and 21b denote the two orifices of the plate 20, and 31a and 31b denote the two orifices of the plate 30. The orifices 21b and 31b, like the orifices 21a and 31a, are vertically aligned. Furthermore, references 41a and 41b denote the two orifices of the plate 40, and 51a and 51b denote the two orifices of the plate 50. The orifices 41b and 51b, like the orifices 41a and 51a, are vertically aligned.

Furthermore, the housing 10A of the force measuring cell 10 is provided with two first through housings 11a, 11b and two second through housings 12a, 12b. Each of the housings is situated in one of the four corners of the force measuring cell 10, when seen from above.

In the assembled configuration of the mechanism 100, the through holes 11a and 11b are respectively aligned with the orifices 21a, 31a and with the orifices 21b, 31b. Furthermore, the through housings 12a and 12b are respectively aligned with the orifices 41a, 51a and 41b, 51b. Furthermore, in the assembled configuration of the mechanism, a first pin 23a is inserted in the housing 11a and in the orifices 21a and 31a, while another pin 23b is inserted in the housing 11b and in the orifices 21b and 31b. Likewise, pins 43a and 43b are respectively inserted in the housing 12a and in the orifices 41a and 51a, on the one hand, and in the housing 12b and the orifices 41b and 51b, on the other hand. The pins 23a, 23b, 43a and 43b are identical.

The pin 23a extends along an axis X23a that is aligned with central axes of the housing 11a and orifices 21a and 31a, in the assembled configuration. A tab 24a extends radially to the axis X23a and crosses through one end 25a of the pin 23a. The tab 24a bears a screw 26a that crosses through a terminal opening of the tab 24a. Thus, the pin 23a is kinetically connected to the screw 26a. Likewise, the pins 23b, 43a and 43b are kinematically connected to the screws 26b, 46a and 46b, by tabs 24b, 44a and 44b.

Each pin 23a, 23b, 43a and 43b is therefore respectively equipped with a stop member 33a, 33b, 53a and 53b made up of a tab 24a, 24b, 44a or 44b and a screw 26a, 26b, 46a or 46b.

Two internal threads denoted 27a and 27b are arranged in the plate 20 and emerge on the surface 28 of that plate opposite its surface 22 and the plate 30. These internal threads are respectively situated near orifices 21a and 21b. Furthermore, two internal threads 47a and 47b are arranged in the plate 40. They emerge on its surface 48 opposite the surface 42 and are respectively situated near orifices 41a and 41b. These internal threads make it possible to receive the screws 26a, 26b, 46a and 46b that belong to the stop members 33a, 33b, 53a and 53b of the pins relative to the plates 20, 30, 40 and 50.

Alternatively, the weighing mechanism only comprises one plate on each side of the weighing mechanism, i.e., for example only the plate 30 and the plate 50, or only the plate 20 and the plate 50.

Another possibility is to have a mechanism similar to that of figures 2 and 3 for which the measuring cell 10 is only provided with two through housings 11a, 12a. This implies only using two pins, a single through orifice per plate and a single thread per plate.

Figure 4 shows a second embodiment in which the weighing mechanism 100 is placed between the mast 6 and the platform 7 using two supports 8 and 9 each comprising a yoke joint 82 or 94. Below, we describe only what differs from the preceding embodiment.

The weighing mechanism 100 is only provided with two pins 23 and 43. This means that each plate 20, 30, 40 and 50 is provided with a single through orifice 21, 31, 41 or 51, the housing 10A of the cell 10 only comprises two through housings 11 and 12 opposite one another, and the first pin 23 is inserted in a first housing 11 and the first orifices 21, 31 of the plates 20 and 30, while the second pin 43 is inserted in the second housing 12 and the orifices 41, 51 of the plates 40 and 50. Furthermore, each pin is provided with two end threads denoted 29 and 29' for the first pin 23 and 49 and 49' for the second pin 43, on each of which a nut 129, 129’, 149 or 149', respectively, is tightened opposite the cell relative to the plates.

To lock the rotation of the housing 10A around the pins 23 and 43, this housing bears flatly against the yoke joints 82 and 94. More specifically, a first planar end face 102 of the housing 10A bears against a planar face 823 of the bottom 822 of the yoke joint 82, between the plates 20 and 30. Likewise, a flat end face 104 of the housing 10A bears against a flat face 943 of the bottom 942 of the yoke joint 94, between the plates 40 and 50.

In one alternative, it is possible to have only a single thread on only one end of each pin 23 or 43 on each of which a nut would be fastened, while a head would be provided at the other end.

It will be noted that regardless of the embodiment, in the nominal usage configuration of the mechanism 100, each pin extends in a direction parallel to the weight of a mass supported by the platform 7.

In an alternative, the platform 7 may be connected to the part 62 directly by means of the weighing mechanism and without the lift being equipped with a pendular arm 63.

The features of the embodiments and alternatives considered above may be combined with one another.

Alternatively, in the nominal usage configuration of the mechanism (100), each pin 23a, 23b, 43a, 43b or 23 and 43 may extend in a direction perpendicular to the weight of a mass supported by the platform.

Whilst one or more preferred embodiments of the present invention have been herein before described, the scope of the present invention is not limited to those specific embodiment(s), and may be embodied in other ways, as will be apparent to a person skilled in the art.

Modifications and variations such as would be apparent to a person skilled in the art are deemed to be within the scope of the present invention.

Claims

The claims defining the invention are as follows:

1. - A weighing mechanism for an aerial lift that comprises a mast and a platform for supporting loads or people, the weighing mechanism comprising - a force measuring cell inserted between the mast and the platform, - at least one first plate secured to a first support supported by the mast and defining a first bearing surface of the cell, the first plate being provided with at least one first through orifice, - at least one second plate secured to a second support supporting the platform and defining a second bearing surface of the cell, the second plate being provided with at least one second through orifice, - at least one first pin, and - at least one second pin, wherein the cell is provided with at least one first through housing aligned with the first through orifice, and at least one second through housing aligned with the second through orifice, in an assembled configuration of the mechanism, and wherein, in the assembled configuration of the mechanism, the first pin is inserted into the first through housing and in the first through orifice, and the second pin is inserted in the second through housing and the second through orifice, and wherein in a nominal usage configuration of the mechanism, each pin extends in a direction parallel to the weight of a mass supported by the platform.
2. - The weighing mechanism according to claim 1, wherein - the first plate and the second plate are each provided with two through orifices, - the mechanism further comprises a third pin and a fourth pin, - the cell is provided with two first through housings respectively aligned with the two first through orifices of the first plate and two second through housings respectively aligned with the two second through orifices of the second plate, in the assembled configuration of the mechanism, and - the first and third pins are inserted in the two first through housings of the cell and in the two first through orifices of the first plate and the second and fourth pins are inserted in the two second through housings of the cell and in the two second through orifices of the second plate, in the assembled configuration of the mechanism.
3. - The weighing mechanism according to any one of the preceding claims, wherein - the mechanism further comprises: - a third plate secured to the first support and defining a third bearing surface of the cell, the third plate being parallel to the first plate and defining, with the first plate and the first support, a first volume in which part of the cell can be inserted, the third plate being provided with at least one third through orifice, - a fourth plate secured to the second support and defining a fourth bearing surface of the cell, the fourth plate being parallel to the second plate and defining, with the second plate and the second support, a second volume in which part of the cell can be inserted, the fourth plate being provided with at least one fourth through orifice, - the first through housing is aligned with the third through orifice and the second through housing is aligned with the fourth through orifice, in the assembled configuration of the mechanism, and - the first pin is inserted in the third through orifice and the second pin is inserted in the fourth through orifice, in the assembled configuration of the mechanism.
4. - The weighing mechanism according to claim 3, wherein - the third plate and the fourth plate are each provided with two through orifices, - the two first through housings of the cell are aligned with the two third through orifices of the third plate and two second through housings of the cell are aligned with the two fourth through orifices of the fourth plate, in the assembled configuration of the mechanism, and - in the assembled configuration of the mechanism, the first and third pins are inserted in the two third through orifices of the third plate and the second and fourth pins are inserted in the two fourth through orifices of the fourth plate.
5. - The weighing mechanism according to any one of the preceding claims, wherein a pin is immobilized relative to a plate through which it crosses using a screwed connection
6. - The weighing mechanism according to any one of the preceding claims, wherein an inner thread is arranged in a plate near its through orifice and the pin is equipped with a member for stopping axial translation able to be screwed in the inner thread of the plate.
7. - The weighing mechanism according to claim 6, wherein the stop member comprises a screw mounted on a tab secured to the pin and which extends radially relative to a central and longitudinal axis of the pin.
8. - The weighing mechanism according to any one of claims 1 to 4, wherein a pin is provided with at least one terminal thread on which a nut is tightened opposite the cell relative to the adjacent plate in the assembled configuration of the mechanism.
9. - The weighing mechanism according to any one of the preceding claims, wherein the force measuring cell comprises a force sensor.
10. - The weighing mechanism according to claim 9, wherein the force sensor is of the strain gauge type.
11. - An aerial lift comprising a chassis equipped with means for moving on the surface of the ground, a platform for supporting loads or people, a mast and means for elevating the platform relative to the chassis, wherein the aerial lift further comprises a weighing mechanism, according to any one of the preceding claims, connecting the platform and the mast.