Articulated lifting device with reduced parasitic forces
Patent Information
- Application Number
- FR2021013251
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-12-10
- Publication Date
- 2025-02-21
- Estimated Expiration
- 2041-12-10
Smart Images
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Abstract
Description
Title of the invention: Articulated lifting device with reduced parasitic forces FIELD OF THE INVENTION
[0001] The present invention relates to the field of lifting and more particularly to the field of articulated lifting arms.
[0002] BACKGROUND OF THE INVENTION
[0003] A lifting device is known comprising a base on which a lifting arm is articulated and which comprises a motorized drum connected to a cable at a first guide point.
[0004] The lifting arm generally comprises a first segment articulated on a second segment about a first axis using a first pivot so as to allow rotation of the second segment relative to the first segment about the first axis. The distal end of the second segment generally comprises a first pulley for guiding the cable towards a load to be lifted. The arm also comprises a second cable return pulley conventionally mounted for rotation about the first axis. The sizing of lifting devices often results in a pulley diameter greater than twenty-five times the diameter of the cable.
[0005] With such a device, when the second segment is moved relative to the first, the tension of the cable creates a resistive torque around the first axis which opposes the relative movement of the segments. Such a torque can prove difficult or even impossible to overcome manually when lifting heavy loads. Incidentally, a displacement of the load is observed caused by the winding of the cable around the pulley. This displacement is all the greater the greater the winding of the cable on the pulley - and therefore the amplitude of the displacement of the second segment relative to the first - is.
[0006] Thus, the prior art articulated arm lifting devices do not allow easy handling of large mass loads over the entire operating range of the arm, nor a constant height of the load during a relative movement of the segments of the articulated arm, unless the arm is instrumented to control the lifting actuator to maintain the load at a constant height. It is then necessary to install a second actuator controlling the articulation between the segments and to instrument the arm to be able to control this actuator in order to maintain intuitive collaborative operation. Such an actuator and its control are expensive and can be dangerous because the actuator generates significant forces which can injure a user and / or their environment. Finally, it is born necessary to control the first actuator according to the relative position of the two segments to compensate for variations in load height. Such equipment increases the manufacturing costs of the arm, increases maintenance costs and provides unsatisfactory ergonomics for the user.
[0007] SUBJECT OF THE INVENTION
[0008] The invention aims in particular to improve the ergonomics and / or the cost of an articulated arm lifting device. Summary of the invention
[0009] For this purpose, a lifting apparatus is provided comprising a base to which a lifting arm is connected and a first actuator connected to a member for transmitting a lifting force by a first guide element which collaborates with the transmission member at a first guide point. The lifting arm comprises a first segment and a second segment. The first segment comprises a first end connected to the base and a second end articulated on a third end of the second segment around a first axis using a first pivot so as to allow rotation of the second segment relative to the first segment around the first axis over a first angular sector. A fourth end of the second segment comprises a second guide element for the transmission member which collaborates with the transmission member at a second guide point.According to the invention, the apparatus comprises a third guide element of the transmission member which collaborates with the transmission member at a third guide point of the transmission member and which is arranged in such a way that a first straight line passing through the second guide point and the third guide point or passing through the first guide point and the third guide point is intersecting with the first axis for a plurality of relative positions of the first segment and the second segment, the plurality of positions covering a portion of the first angular sector at least equal to half of the first angular sector.
[0010] Thus, the first straight line being intersecting with the first axis 01, the device eliminates any parasitic torque that could oppose the rotation of the first segment relative to the second segment around the first axis. The user no longer has to exert any effort to combat a parasitic torque. A passive embodiment, that is to say without actuation other than that of the first actuator, makes it possible to obtain an economical, reliable and efficient device.
[0011] No variation in the height of the load is obtained during the relative rotation of the first and second elements when the third guide element is arranged so that a length of the transmission member between the first guide point and the second guide point is constant for the plurality of relative positions of the first segment and the second segment. This makes it possible to avoid having to instrument the first actuator and allows control of the first actuator in a fixed position.
[0012] The ergonomics and comfort of use of the device are improved when the first angular sector is substantially equal to one hundred and eighty degrees and / or the first portion is substantially equal to one hundred percent of the first angular sector.
[0013] A simple design of the apparatus is obtained when the third guide element comprises a first return of the transmission member mounted in a movably manner relative to the first segment and to the second segment, the apparatus comprising first path means which define a first trajectory of a first center of the first return of the transmission member.
[0014] The apparatus is particularly economical to produce when at least a first roller is connected to the first return of the transmission member and the first routing means comprise at least a first rolling path of the first roller.
[0015] Advantageously, the first trajectory is an involute type trajectory and / or the first trajectory depends on the distance which separates the first guide point and the first axis and / or the first trajectory also depends on a first winding radius of the transmission member around the first return.
[0016] According to a preferred embodiment, the first trajectory groups together all the points M whose coordinates in an orthonormal reference frame centered on the first axis and in which an abscissa axis coincides with a second straight line connecting the first guidance point and the first axis solve the following system of equations:
[0017] [Math.l] ' L [. (1 - cosÔ)+^.( / i7.cosô - sin / 5) - r b + sin# ) = 0 1 - L^sinS + r v ( ^7.sinô + cosÔ ) - ( / ? r sin0 - cos# ) = 0 ^ + / ^+3-5-^ = 0
[0018] With
[0019] X, an abscissa of the point M such that X= rl*(Pl*cos0 + sinO);
[0020] Y, an ordinate of the point M such that Y= rl*(|31*sin0 - cosO);
[0021] 0 an angle formed by the first segment and the second segment;
[0022] rl: the first radius of winding of the transmission member around the first return.
[0023] Preferably, the first straight line passes through the second guide point and the third guide point and the first routing means are integral with the first segment. Alternatively, the first straight line passes through the first guide point and the third guide point and the first means of routing are integral with the second segment.
[0024] The reliability of the apparatus is improved when the first pathing means comprise a first stop and a second end-of-travel stop.
[0025] Advantageously, the first routing means comprise a second roller connected to the first return of the transmission member and the first routing means comprise a second rolling path of the second roller.
[0026] The intervention range is increased when the third guide element comprises a second return of the transmission member mounted in a movably manner relative to the first segment and to the second segment, the lifting apparatus comprising second path means which define a second trajectory of a second center of the second return of the transmission member.
[0027] Preferably again, at least one third roller is connected to the second cable return and the second routing means comprise at least one third rolling path of the third roller and / or the first return of the transmission member and the second return of the transmission member are rigidly connected to each other.
[0028] The reliability of the apparatus is further improved when the second pathing means comprise a third stop and a fourth end-of-travel stop.
[0029] The adaptability of the apparatus is further improved when the second segment is configured such that a distance separating the second guide point and the first axis is modifiable. Use of the apparatus is facilitated when the apparatus comprises a second actuator for modifying the distance separating the second guide point and the first axis.
[0030] It is possible to install a pulley or to carry out actuation of the load in two directions when the second guide element and / or the third guide element are arranged to collaborate with a plurality of transmission members.
[0031] A simple and robust device is obtained when the transmission member is a cable.
[0032] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. Brief description of the drawings
[0033] Reference will be made to the accompanying drawings, among which:
[0034] [Fig-1] [Fig.l] is a schematic perspective view of a lifting device according to a first embodiment of the invention;
[0035] [Fig.2] [Fig.2] is a partial schematic perspective view of the apparatus of lifting of the [Fig.l];
[0036] [Fig.3] [Fig.3] is a partial schematic perspective view of detail of the lifting apparatus of [Fig.l];
[0037] [Fig.4] [Fig.4] is a partial planar schematic representation of the apparatus of lifting of the [Fig.l];
[0038] [Fig.5] [Fig.5] is a partial schematic perspective view of the apparatus of lifting according to a second embodiment of the invention;
[0039] [Fig.6] [Fig.6] is a detailed perspective view of a third guide point according to a second embodiment of the invention;
[0040] [Fig.7] [Fig.7] is a partial planar schematic representation of the apparatus of lifting of [Fig.5];
[0041] [Fig.8] [Fig.8] is a partial schematic cross-sectional representation of the apparatus lifting according to a third embodiment of the invention;
[0042] [Fig.9] [Fig.9] is a detailed perspective view of a third guide point according to a fourth embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION
[0043] With reference to [Fig. 1], the lifting apparatus according to the invention and generally designated 1, comprises a base 2 comprising a foot 3 connected to a support 4, here horizontal in the representations of figures 1 to 4.
[0044] The base 2 comprises a vertical tube 5 on the upper end 6 of which a lifting arm 10 is articulated.
[0045] The apparatus 1 comprises a geared motor 20 connected to a lifting cable 21 by a drum 22 which collaborates with the cable 21 at a first guide point 23 corresponding here to the point of tangency of the cable 21 on the drum 22. The arm 10 comprises a first segment 30 and a second segment 40 articulated relative to each other around a first axis 01, here a vertical axis. The segment 30 comprises a first end 31 articulated on the base 2 around a second axis 02, here substantially parallel to the axis 01, and a second end 32 articulated on a third end 41 of the segment 40 around the axis 01 using a first pivot 11 comprising, in a known manner, a vertical shaft not shown for the sake of clarity. The pivot 11 allows a rotation of the segment 40 relative to the segment 30 around the axis 01 on a first angular sector Sal here equal to one hundred and sixty degrees, an angle of one hundred and eighty degrees corresponding to an alignment of the segments 30 and 40..
[0046] The segment 40 comprises a fourth end 42 provided with a sheave 43 mounted to rotate along a third horizontal axis 03 and which collaborates with the cable 21 at a second guide point 44 - corresponding here to any one of the points of tangency of the cable 21 on the sheave 43. The first guide point 23 is separated from the axis 01 by a first distance L1 (see [Fig.2] and 4), corresponding substantially to a first length of the first segment 30. The second guide point 44 is separated from the axis 01 by a second distance L2, corresponding substantially to a second length of the segment 40.
[0047] The apparatus 1 comprises a third guide element 50 for the cable 21 which collaborates with the cable 21 at a third guide point 51 for the cable 21. The element 50 comprises a first pulley 52 of first radius rl mounted to rotate around a first shaft 53 (visible [Fig. 3]) substantially vertical which passes through a first center of rotation 54 of the pulley 52. The upper end 53.1 of the shaft 53 is provided with a first roller 55 and the lower end 53.2 of the shaft 53 is provided with a second roller 56. The element 50 also comprises a first raceway 60 and a second raceway 61 both integral with the segment 30. The races 60 and 61 respectively define the position of the rollers 55 and 56 and, incidentally, define a first trajectory 57 of the center 54. Trajectory 57 is here an involute type trajectory.The third guide point 51 corresponds, here, to the point of tangency of the cable 21 on the pulley 52 which is closest to the point 44.
[0048] The trajectory 57 can be defined as grouping together all the points M (X; Y) whose coordinates in an orthonormal reference frame O(w,v) linked to the first segment 30, centered on the axis 01 of axes (Ox, Oy) and in which the abscissa axis Ox coincides with a second straight line D0 connecting the first guidance point 23 and the first axis 01 solve the following system of equations:
[0049] [Math.l] 'L^ 1-cosô) +^.( / ^£085-810(5) -r^^^.cos^ + sin^) -0 1 -Lj.sin<5 + r } .( / î23dn5 + œ^ -r].( / î r sin0-cos0) =0
[0050] With
[0051] X, an abscissa of the point M such that X= rl*(|31*cos0 + sinO);
[0052] Y, an ordinate of the point M such that Y= rl*(|31*sin0 - cosO);
[0053] L1 a first distance separating the first guide point 23 from the first axis 01;
[0054] rl: the first winding radius of the first pulley 52;
[0055] 0 an angle formed by the first segment 30 and the second segment 40;
[0056] the angles [31 and [32 each represent an angular portion of winding of the cable on the pulley 52, the angle δ being defined by the last equation of the system of equations above.
[0057] The equation system Math 1 includes three equations, three unknowns [31, [32 and ô and a parameter 0. Thus, the equation system Math 1 can be written in the form f([31,0)=0. For a value of the angle 0 between twenty and one hundred and eighty degrees, it is easy to determine [31 and then deduce the position of point M for this value of 0. We then proceed by successive calculations to determine the trajectory 57 for a value of angle 0 between 0 and one hundred and eighty degrees.
[0058] The first trajectory 57 thus defined depends, here, on the first distance L1 which separates the first guide point 23 and the first axis 01. The first trajectory 57 also depends on the first radius rl of winding of the cable 21 around the first pulley 52.
[0059] The equation system Math 1 represents a particular mathematical expression, among other possible ones, of an arrangement of the apparatus 1 which allows the following conditions to be respected when varying the angle between the two segments: a. a first straight line DI passing through the second guide point 44 and the third guide point 51 is secant with the first axis 01; b. a length L21 of the cable 21 between the first guide point 23 and the second guide point 44 is constant.
[0060] The inventor has found that the function defined implicitly in the form f([31,0)=0 is derivable and continuous for values of the angle 0 included in the first angular sector Sal not reduced to a point included or equal to the interval between twenty and one hundred and eighty degrees, and that thus f([31,0)=0 makes a single value of [31 correspond to each value of the angle 0 of the first angular sector Sal.
[0061] As visible in figures 2 and 3, the first raceway 60 comprises at its end 60.1 a first upper end-of-travel stop 70.1 and at its end 60.2 a second upper end-of-travel stop 70.2.
[0062] The second upper stop 70.2 comprises a first rectilinear section 70.3 which extends tangentially to the rolling path 60 to connect a first wall 70.4 which extends substantially orthogonally to the first section 70.3.
[0063] Identicaly, the second raceway 61 comprises at its end 61.1 a first lower end-of-travel stop 71.1 and at its end 61.2 a second lower end-of-travel stop 71.2. The second lower stop 71.2 comprises a second rectilinear section 71.3 which extends tangentially to the raceway 61 to connect a second wall 71.4 which extends substantially orthogonally to the second section 71.3.
[0064] In operation, when an operator moves the segment 40 relative to the segment 30 between two points of the first angular sector Sal, the center 54 of the pulley 52 moves along the trajectory 57 thanks to the paths 60 and 61 with which the rollers 55 and 56 collaborate. This arrangement guarantees that the length L21 remains constant and that thus a height of a load 100 coupled to the cable 21 does not vary during the relative movement of the segments 30 and 40 over the entire angular sector Sal when a rotation of the drum 22 is blocked. The fact that the first straight line DI remains secant with axis 01 eliminates any parasitic torque which could oppose the rotation of segment 30 relative to segment 40 around axis 01.
[0065] Elements similar or analogous to those previously described will bear a numerical reference identical to these in the following description of a second, third and fourth embodiment of the invention.
[0066] According to a second embodiment shown in figures 5 to 7, the pivot 11 allows a rotation of the segment 40 relative to the segment 30 around the axis 01 on an angular sector Sal here equal to three hundred and twenty degrees. The element 50 comprises a second pulley 80 of second radius r2 - here equal to rl - mounted to rotate around a second substantially vertical shaft 81 which passes through a second center of rotation 82 of the pulley 80. The upper end 81.1 of the shaft 81 is provided with a third roller 83 and the lower end 81.2 of the shaft 81 is provided with a fourth roller 84. The element 50 also comprises a third raceway 85 and a fourth raceway 86 both integral with the segment 30. The races 85 and 86 respectively define the position of the rollers 83 and 84 and, incidentally, define a second trajectory 87 of the center 82.The trajectory 87 is here an involute type trajectory and can be defined as being the symmetrical curve of the trajectory 57 with respect to the plane defined by the first axis 01 and the first guide point 23.
[0067] As seen in [Fig.6], an arm 88 connects the shaft 53 and the shaft 81. The arm 88 comprises an upper flange 88.1 and a lower flange 88.2.
[0068] As seen in Figures 5 and 7, the third raceway 85 comprises at its ends 85.1 and 85.2 a third upper end-of-travel stop 90.1 and a fourth upper end-of-travel stop 90.2. Identicaly, the fourth raceway 86 comprises at its ends 86.1 and 86.2 a third lower end-of-travel stop 91.1 and a fourth lower end-of-travel stop 91.2.
[0069] The stop 70.2 comprises, in this second embodiment, a first upper wall 70.5 which extends substantially parallel to the first section 70.3 to form a substantially C-shaped housing for receiving the roller 55. Similarly, the stop 71.2 comprises a first lower wall 71.5, which extends substantially parallel to the second section 71.3 to form a substantially C-shaped housing for receiving the roller 56.
[0070] The third upper stop 90.1 comprises a third rectilinear section 90.3 which extends tangentially to the rolling track 85 to connect a third wall 90.4 which extends substantially orthogonally to the third section 90.3. A third upper wall 90.5 extends substantially parallel to the third section 90.3 to form a substantially C-shaped housing for receiving the roller 83.
[0071] Similarly, the fourth lower stop 91.1 comprises a fourth rectilinear section 91.3 which extends tangentially to the rolling path 86 to connect a fourth wall 91.4 which extends substantially orthogonally to the fourth section 91.3. A fourth lower wall 91.5 extends substantially parallel to the fourth section 91.3 to form a substantially C-shaped housing for receiving the roller 84.
[0072] In operation, when an operator moves the segment 40 relative to the segment 30 between two points of the first angular sector Sal, the center 54 of the pulley 52 moves along the trajectory 57 thanks to the paths 60 and 61 with which the rollers 55 and 56 collaborate when the angle 0 is between twenty and one hundred and eighty degrees. During this movement of the rollers 55 and 56, the rollers 83 and 84 move along the paths 85 and 86 on the sections 90.3 and 91.3. When the angle 0 reaches one hundred and eighty degrees, the rollers 55 and 56 are respectively in contact with the stops 70.1 and 71.1, and the rollers 83 and 84 are respectively in contact with the stops 90.1 and 91.1. Cable 21 is then tangent to pulleys 52 and 80 ([Fig.7]).
[0073] When an operator moves the segment 40 relative to the segment 30 so that the angle 0 is between one hundred and eighty degrees and three hundred and forty degrees, the center 82 of the pulley 80 moves along the trajectory 87 thanks to the paths 85 and 86 with which the rollers 83 and 84 collaborate. During this movement of the rollers 83 and 84, the rollers 55 and 56 move along the paths 60 and 61 on the sections 70.3 and 71.3.
[0074] This arrangement ensures that the length L21 remains constant and that thus a height of a load 100 coupled to the cable 21 does not vary during the relative movement of the segments 30 and 40 over the entire angular sector Sal when a rotation of the drum 22 is blocked. The fact that the first straight line DI remains secant with the axis 01 eliminates any parasitic torque which could oppose the rotation of the segment 30 relative to the segment 40 around the axis 01.
[0075] According to a third embodiment shown in [Fig.8], the segment 40 is telescopic and comprises a first part 45 which receives a second sliding part 46. The part 45 carries the third end 41 and the part 46 carries the fourth end 42.
[0076] The segment 40 comprises a pneumatic cylinder 47 whose body 48 is connected to the part 45 and the rod 49 is connected to the part 46. It is then possible to modify the distance L2 by acting on the cylinder 47.
[0077] According to a fourth embodiment shown in [Fig.9], the shaft 53 can receive a plurality of first pulleys. As seen in [Fig.9], the shaft 53 comprises a first upper pulley 52.1, a first middle pulley 52.2 and a third lower pulley 52.3. Consequently, the end 42 then comprises several 43 sheaves.
[0078] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.
[0079] In particular,
[0080] - although here the arm is articulated at the base, the invention also applies to other types of connection of the arm to the base such as a recessed connection. The base can also consist of a vertical or oriented wall in any way to which the arm is connected;
[0081] - although here the apparatus comprises a cable connected to an actuating geared motor of a drum, the invention also applies to other types of members for transmitting a lifting force and their associated actuators such as for example a toothed wheel which meshes with a chain, a toothed or non-toothed belt or a ribbon and a wheel, a hybrid member comprising connecting rods connected by cable, or any jack applying a traction force to any other type of transmission member;
[0082] - although here the first angular sector is equal to one hundred and sixty degrees, the invention also applies to other values of the first sector between zero and three hundred and sixty degrees;
[0083] - although here the apparatus comprises a sheave, the invention also applies to other types of second guide element of the transmission member such as for example an eyelet, or a fixed shaft;
[0084] - although here the third guide element comprises a pulley, the invention also applies to other types of transmission member return such as for example an axle, a toothed wheel, a sheave, a guide eyelet or a chute;
[0085] - although here the cable cooperates with a first pulley of first radius, the invention also applies to other types of first cable return whose winding radius is a function of their design, thus, a cylindrical return effecting a cable return by rolling or sliding has a cable winding radius equal to the radius of the cylinder, a cable return by eyelet has a rolling radius equal to the radius of the eyelet, a return by articulated chute includes a winding radius corresponding to the distance separating the point of contact of the cable from the articulation;
[0086] - although here the first cable return is rotatably mounted on a shaft provided with rollers which cooperate with a path, the invention also applies to other methods of producing a mobile connection of the first return relative to the first segment and to the second such as for example a shaft whose surface would be treated or not to limit friction and which would collaborate with a light, or even a slide mounted on a guide rail;
[0087] - although here the first shaft is provided with two rollers collaborating with two tracks rolling, the invention also applies to a single roller collaborating with a single track or more than two rollers collaborating with more than two tracks;
[0088] - although here the third guide element comprises two rolling paths, the invention also applies to other means of routing such as for example a single rolling path, a sliding track, a light in a solid, a slide on a rail or any other means of defining a trajectory of an element;
[0089] - although here the first trajectory depends on the first distance and the radius winding, the invention also applies to a first trajectory depending only on the first radius or the first distance or another parameter;
[0090] - although here the system is arranged so that the first straight line is secant with the first axis over the whole of a first angular sector between zero and one hundred and eighty degrees, the invention also applies to other arrangements of the system which make it possible to fulfill this condition for a plurality of positions covering a portion of the first angular sector at least equal to half of the first angular sector, such as for example an arrangement of the system which respects the condition of intersection of the first straight line and the first axis only over a portion equal to seventy-five percent of the first angular sector;
[0091] - although here the cable cooperates with a second pulley of second radius, the invention also applies to other types of second cable return whose winding radius is a function of their design, thus, a cylindrical return effecting a return of the cable by rolling or sliding has a winding radius of the cable equal to the radius of the cylinder, a cable return by eyelet has a rolling radius equal to the radius of the eyelet, a return by articulated chute comprises a winding radius corresponding to the distance separating the point of contact of the cable from the articulation;
[0092] - although here an arm connects the first support shaft of the first pulley and the second shaft supporting the second pulley, the invention also applies to other means of rigidly connecting the first and second pulleys to each other, such as for example a connecting rod, a lattice structure or arms integral with the ends of the shafts;
[0093] - although here the second segment comprises a pneumatic cylinder, the invention also applies to other types of second actuator such as for example a geared motor / pulley / cable assembly, a hydraulic cylinder, a motorized rack. The invention also applies to a configuration of the second segment which allows its length to be modified without using an actuator such as for example manual action on the two parts of the second segment and the activation of a manual pin type lock for example;
[0094] - although here the first shaft comprises three first pulleys and the second guide element comprises three sheaves, the invention also applies to other arrangements of the second and third guide points making it possible to receive a plurality of cables, such as for example two pulleys per guide point, or more than three.
[0095] - although here the first means of travel are integral with the first segment, the invention also applies to a kinematic inversion of the third guide element according to which the first path means would be integral with the second arm segment when the first straight line passes through the first guide point and the second guide point.
Claims
Claims
1. Lifting apparatus (1) comprising a base (2) to which a lifting arm (10) is connected and a first actuator (20) connected to a transmission member (21) of a lifting force by a first guide element (22) which collaborates with the transmission member (21) at a first guide point (23), the lifting arm (10) comprising a first segment (30) and a second segment (40), the first segment (30) comprising a first end (31) connected to the base (2) and a second end (32) articulated on a third end (41) of the second segment (40) around a first axis (01) using a first pivot (11) so as to allow rotation of the second segment (40) relative to the first segment (30) around the first axis (01) on a first angular sector (Sal),a fourth end (42) of the second segment (40) comprising a second guide element (43) of the transmission member (21) which collaborates with the transmission member (21) at a second guide point (44), characterized in that the apparatus (1) comprises a third guide element (50) of the transmission member (21) which collaborates with the transmission member (21) at a third guide point (51) of the transmission member (21) and which is arranged so that a first straight line (Dl) passing through the second guide point (44) and the third guide point (51) or passing through the first guide point (23) and the third guide point (51) is intersecting with the first axis (01) for a plurality of relative positions of the first segment (30) and the second segment (40), the plurality of positions covering a portion of the first angular sector (Sal) at least equal to half of the first angular sector (Sal),wherein the third guide element (50) is arranged so that a length of the transmission member (21) between the first guide point (23) and the second guide point (44) is constant for the plurality of relative positions of the first segment (30) and the second segment (40), wherein the third guide element (50) comprises a first return (52) of the transmission member (21) mounted movably relative to the first segment (30) and the second segment (40), 1 r F ' lifting apparatus (1) comprising first tracking means (60, 61) which define a first trajectory (57) of a first center (54) of the first return (52) of the transmission member (21). ^Claim 2] L se F ^Claim 3] LF t FF ^Claim 4] t F ^Claim 5] L c 1 ^Claim 6] L cr F ^Claim 7] t F cc ( r Lifting apparatus (1) according to claim 1, wherein the first angular sector (Sal) is substantially equal to one hundred and eighty degrees and / or the first portion is substantially equal to one hundred percent of the first angular sector (Sal). Lifting apparatus (1) according to claim 1, wherein at least one first roller (55, 56) is connected to the first return (52) of the transmission member (21) and the first routing means (60, 61) comprise at least one first rolling path (60, 61) of the first roller (55, 56).Lifting apparatus (1) according to claim 1 or 3, wherein the first trajectory (57) is an involute type trajectory. Lifting apparatus (1) according to any one of claims 2 to 4, wherein the first trajectory (57) depends on the distance which separates the first guide point (23) and the first axis (01). Lifting apparatus (1) according to any one of claims 2 to 5, wherein the first trajectory (57) also depends on a first path (rl) of winding of the transmission member (21) around the first return (52). Lifting apparatus (1) according to claims 5 and 6, in which the first trajectory (57) groups together all the points M whose coordinates in an orthonormal reference frame centered on the first axis (01) and in which an abscissa axis coincides with a second straight line (DO) connecting the first guide point (23) and the first axis (01) solve the following system of equations: ' Lp ( 1 - cosÔ ) + r [. ( {3?.cosÔ - sinÔ ) -1^.( f^cosO + sin0 ) = 0 - L^sinô + rb ( P2.sinô + cosÔ ) - q. ( P rsin0 - cos0 ) = 0 ^+^ + 0-0-31 = 0 t ; 5 E ra \.vec C, an abscissa of the point M such that X= rl*(01*cosO + sinO) ; f, an ordinate of the point M such that Y= rl*(|31*sin0 - cosO) ; an angle formed by the first segment and the second segment; 1: the first winding radius of the transmission member (21) around the first return (52).
8. Lifting apparatus (1) according to any one of claims 2 to 7, in which the first straight line (D1) passes through the second guide point (44) and the third guide point (51) and the first routing means (60, 61) are integral with the first segment (30).
9. Lifting apparatus (1) according to any one of claims 2 to 7, in which the first straight line (D1) passes through the first guide point (23) and the third guide point (51) and the first routing means (60, 61) are integral with the second segment (30).
10. Lifting apparatus (1) according to any one of claims 2 to 9, wherein the first path means (60, 61) comprise a first end-of-travel stop (70.1, 70.2) and a second end-of-travel stop (71.1, 71.2).
11. Lifting apparatus (1) according to any one of claims 2 to 10, in which the first path means (60, 61) comprise a second roller (56) connected to the first return (52) of the transmission member (21) and the first path means (60, 61) comprise a second raceway (61) of the second roller (56).
12. Lifting apparatus (1) according to any one of claims 2 to 11, in which the third guide element (50) comprises a second return of the transmission member (80) mounted movably relative to the first segment (30) and to the second segment (40), the lifting apparatus (1) comprising second path means (85, 86) which define a second trajectory (87) of a second center (82) of the second return (80) of the transmission member (21).
13. Lifting apparatus (1) according to claim 12, in which at least one third roller (83, 84) is connected to the second return (80) of the transmission member (21) and the second routing means comprise at least one third rolling path (85) of the third roller (83).
14. Lifting apparatus (1) according to claim 13, wherein the first return (52) of the transmission member (21) and the second return (80) of the transmission member (21) are rigidly connected to each other.
15. Lifting apparatus (1) according to any one of claims 12 to 15. 14, wherein the second path means (85, 86) comprise a third end-of-travel stop (90.1, 90.2) and a fourth end-of-travel stop (91.1, 91.2).
16. Lifting apparatus (1) according to any one of the preceding claims, wherein the second segment (40) is configured such that a distance (L2) separating the second guide point (44) and the first axis (01) is modifiable.
17. Lifting apparatus (1) according to claim 16, comprising a second actuator (47) for modifying the distance (L2) separating the second guide point (44) and the first axis (01).
18. Lifting apparatus (1) according to any one of the preceding claims, wherein the second guide element (43) and the third guide element (50) are arranged to collaborate with a plurality of transmission members (21).
19. Lifting apparatus (1) according to any one of the preceding claims, in which the transmission member (21) is a cable.