Transport system

Abstract

Transport system (10) for transporting objects, comprising a stationary sliding track (11) defining a continuous sliding path free of interruptions, a mobile unit (12) movable on the sliding track (11) in a direction of advance (A), and drive means to move the mobile unit (12) on the sliding track (11). The transport system (10) comprises an inner rolling guide (16) and an outer rolling guide (17), which are arranged on an inner side (30) and on an outer side (31), respectively, of said sliding track (11), and an inner rolling unit (18) and an outer rolling unit (19) which are configured to cooperate, according to a rolling relationship, with the inner and outer rolling guides (16, 17), respectively.

Description

[0001] “TRANSPORT SYSTEM”

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns a system for transporting objects, in particular but not only, along a closed-loop path comprising both straight segments and also curved segments. Preferably, the transport system according to the present invention provides to use electromagnetically driven linear motors, but more generally it can find advantageous application in indexed, or moved “stepwise”, belt / chain transport systems.

[0004] BACKGROUND OF THE INVENTION

[0005] In the field of industrial automation, automated transport systems capable of transporting objects, typically between different processing stations provided in an industrial processing line, are well known.

[0006] Such transport systems comprise a conveying member, which defines a path along which the objects move.

[0007] In some solutions known in the art, the conveying members are configured as belts, chains or other similar transport components, closed in a loop on at least one pair of pulleys, wherein at least one pulley is motorized to determine, with its rotation, the advance of the aforementioned conveying members on which the aforementioned objects lie resting.

[0008] In other solutions known in the art, the conveying members are configured as a plurality of transport trolleys, each supporting one or more objects, and sliding on a fixed linear guide. The guide comprises straight and curved segments, which develop in such a way as to allow the trolleys conveying the objects to follow the advance path provided. An example of this type of solutions, in which transport trolleys are guided by means of rollers on fixed guides, is described in European patent EP-B 1-2544974, by the same Applicant, which describes a transport system according to the preamble of the independent claim 1.

[0009] A technology widely used in solutions known in the art is that of linear motors with electromagnetic drive. This provides that each transport trolley comprises a permanent magnet cooperating with a plurality of electromagnets that are drowned in the fixed guide, in such a position as to be facing the aforementioned permanent magnets, with the interposition of a magnetic gap between them. The permanent magnets, in cooperation with the electromagnets, allow to drive the transport trolleys by selectively activating the electromagnets when a particular transport trolley is to be driven, which moves thanks to the electromagnetic field generated, according to modes known in the art.

[0010] The transport systems that employ linear motors with electromagnetic drive have long been used in many industrial sectors, such as in that of packaging products into primary or secondary packaging, for example. These linear motors, in fact, have very high performance levels, since they allow to have high accelerations and to command the movement of the transport trolleys independently.

[0011] A disadvantage of traditional transport systems is the presence of significant design constraints, in particular to allow the correct advance of the transport trolleys in closed paths formed by straight segments and curved segments. In fact, the geometry of the transport trolleys depends strictly on the characteristics of the curved segments, in particular their radius of curvature. As will be easily understood, in the passage from the straight segments to the curved segments, the trolley must be able to follow the path without any interruption.

[0012] Therefore, the transition of the transport trolleys from the straight segments to the curved segments, and vice versa, entails considerable design constraints that designers have to face. In fact, in the transition between these segments, the transport trolley tends to deviate from the guide due to the fact that the instantaneous variation of the direction of the speed vector in this transition entails a discontinuity of the acceleration, which causes the transport trolley to detach from the linear guide.

[0013] To try to overcome these disadvantages, the Applicant has devised and developed a perfected transport system, described in international patent application WO 2022 / 03745, in which there are provided transport trolleys mobile along a stationary sliding track which is provided with a plurality of shaped guides defining cam profiles on which respective rolling elements slide. The shape of the shaped guides, in particular in the curved segments of the track and / or in the transition segments between the straight segments and the curved segments, is such as to allow the above-described disadvantages of the state of the art to be overcome. However, in the transport system described by WO 2022 / 03745 the relative arrangement between the rolling elements and the stationary sliding track is such as to guarantee the correct advance of the trolleys only with limited load capacities. In fact, the excessive weight of the objects transported, and / or their asymmetrical arrangement not barycentric with respect to the trolley, could determine the accidental disengagement between the rolling elements and the sliding track, in particular while the trolleys travel the curved segments and / or the transition segments.

[0014] It is evident that this is disadvantageous because it constitutes a constraint with regards to the nature, weight and overall dimensions of the objects that have to be transported, because this system is able to safely transport only light objects of reduced volume.

[0015] There is therefore the need to perfect a transport system that can overcome at least one of the disadvantages of the state of the art. In particular, one purpose of the present invention is to provide a transport system that is reliable during use, to guarantee the system operates correctly, in particular while the transport trolleys make the transition from the straight segments to the curved ones, and vice versa.

[0016] Another purpose of the present invention is to provide a transport system in which each transport trolley has a greater load capacity than the trolleys known in the state of the art, so as to be able to move heavier and bulkier objects than those transportable with trolleys known in the state of the art.

[0017] Another purpose of the present invention is to provide a transport system in which the objects can remain arranged in a stable manner on the transport trolleys, in particular even along the curved segments and / or in the transition between the straight segments and the curved segments.

[0018] Another purpose of the present invention is to provide a transport system in which the anchoring of the transport trolleys to the sliding track is firm, resistant and whose coupling clearances between rolling elements and guides remain constant in any segment that the trolleys travel along the path, in particular in the segments of transition between the straight segments and the curved segments.

[0019] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0020] SUMMARY OF THE INVENTION

[0021] The present invention is set forth and characterized in the independent claims.

[0022] The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0023] In accordance with the above purposes, a transport system for transporting objects is provided which overcomes the limits of the state of the art and eliminates the defects present therein.

[0024] According to one aspect of the present invention, the transport system comprises:

[0025] - a sliding track having an inner side and an outer side opposite to and distanced from each other;

[0026] - a mobile unit movable on the sliding track along a sliding path having at least a curved path portion and at least a straight path portion; - drive means configured to move the mobile unit on the sliding track.

[0027] The sliding track comprises:

[0028] - an inner rolling guide on the inner side of the sliding track, wherein the inner rolling guide has at least one inner straight portion, at least one inner curved portion and an inner transition portion interposed between the inner straight portion and the inner curved portion, and wherein the inner rolling guide comprises a first and a second cams having, respectively, an inner upper rolling surface and an adjacent inner lower rolling surface,

[0029] - an outer rolling guide on the outer side of the sliding track, wherein the outer rolling guide has at least one outer straight portion, at least one outer curved portion and an outer transition portion interposed between the outer straight portion and the outer curved portion, and wherein the outer rolling guide comprises a third and a fourth cams having, respectively, an outer upper rolling surface and an adjacent outer lower rolling surface, wherein the inner upper rolling surface and the outer upper rolling surface are parallel to each other along the entire sliding path, while the inner lower rolling surface and the outer lower rolling surface are parallel to each other along the entire sliding path.

[0030] The mobile unit comprises: - at least one inner rolling unit configured to engage with the inner rolling guide and comprising a first and a second rolling element which are configured, respectively, to roll over the inner upper and lower rolling surfaces, the first and second rolling elements rotating around respective first and second rolling axis which are parallel to each other,

[0031] - an outer rolling unit configured to engage with the outer rolling guide, comprising a third and a fourth rolling element which are configured, respectively, to roll over the outer upper and lower rolling surfaces, the third and fourth rolling elements rotating, respectively, around third and fourth rolling axis which are parallel and distant from each other.

[0032] According to one aspect of the present invention, the first and third rolling elements are arranged opposite to each other and the second and fourth rolling elements are arranged opposite to each other.

[0033] According to another aspect of the present invention, on the inner and outer transition portions, the upper rolling surfaces, respectively inner and outer, follow a profile which is different from the profile followed by the lower rolling surfaces, respectively inner and outer, so as to define a varying outer cam profile deviation between the outer upper rolling surface and the outer lower rolling surface along the outer transition portion, and a varying inner cam profile deviation between the inner upper rolling surface and the inner lower rolling surface along the inner transition portion, so as to simultaneously maintain all four of the rolling elements in contact with the inner and outer transition portions during movement along the sliding track.

[0034] According to one aspect of the present invention, a distance between the inner upper rolling surface and the outer upper rolling surface, as well as between the inner lower rolling surface and the outer lower rolling surface is invariable and remains constant along the inner and outer transition portions, respectively; the distance being measured perpendicular to a plane tangent point-by-point to the rolling surfaces. An advantage of the transport system according to the present invention is eliminating the design constraints which in the state of the art significantly limit the load capacity of the mobile units, thus being able to transport objects of larger sizes and weight compared to the solutions known in the state of the art, and of providing a transport system in which the anchoring of the transport trolleys to the sliding track is firm, resistant and whose coupling clearances between rolling elements and guides remain constant in any segment that the trolleys travel along the path, in particular in the portions of transition between the straight segments and the curved segments.

[0035] This is possible, on the one hand, thanks to the presence of the inner and outer cam profile deviations, which are variable in the transition portions, which allows the mobile unit to be arranged, with respect to the sliding track, in such a way as not to detach from the track itself, since the profile of the rolling surfaces is such as to compensate for the different point-by-point curvature in which the mobile unit is located in these transition portions, and on the other hand thanks to the fact that the rolling elements constrain the mobile unit to remain in contact with both the inner side and the outer side of the sliding track.

[0036] The mobile unit is therefore constrained to the sliding track both on the inner and also on the outer side.

[0037] This makes the anchoring to the track much more stable compared to solutions known in the state of the art, such as for example the one described by WO 2022 / 03745, in which the mobile units are constrained to the track only at one side, specifically the outer one. This configuration of the mobile units allows to have a more balanced distribution of forces, which does not lead to dynamic imbalances during the movement of the mobile units along the sliding track.

[0038] DESCRIPTION OF THE DRAWINGS

[0039] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of an embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

[0040] - fig. 1 is a schematic and simplified perspective view of a transport system in accordance with the teachings of the present invention;

[0041] - fig. 2 is a schematic and simplified top plan view of an enlarged portion of the transport system of fig. 1 ; - fig. 3 is a schematic section view taken along the trace line III-III of fig. 4;

[0042] - figs. 4, 5 and 6 are simplified and schematic section views, taken along trace lines IV-IV, V-V and VI- VI, respectively, of fig. 2;

[0043] - figs. 7 and 8 are schematic, simplified and enlarged top plan views of a mobile unit comprised in the transport system of fig. 1 , shown while it is traveling along a transition portion between a straight segment and a curved segment;

[0044] - fig. 9 is a Cartesian graph showing the trend of the cam profile deviation along the sliding path. To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

[0045] DESCRIPTION OF SOME EMBODIMENTS We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings, by way of a nonlimiting illustration. The phraseology and terminology used here is also for the purposes of providing non-limiting examples.

[0046] With reference to fig. 1, a transport system for transporting objects is described, which is indicated as a whole with reference number 10.

[0047] The objects, which are not shown in the attached drawings, can for example be products to be assembled, within the context of an automated production line, in particular in the packaging sector. It is quite evident that the transport system in accordance with the present invention is suitable to transport many different types of objects, without the type, shape and sizes of the objects affecting the scope of protection of the present invention.

[0048] The transport system 10 comprises a stationary sliding track 11 extending along a continuous sliding path free from interruptions.

[0049] The transport system 10 also comprises a guide base 33, the shape of which can follow that of the stationary sliding track 11 , arranged below the latter.

[0050] In the example shown, visible in fig. 1 , the sliding track 11 has a long and narrow shape, substantially inscribable within a rectangle, and comprises two straight portions and two curved portions reciprocally connected according to an alternating sequence. It should be noted that the sliding path, indicated with reference A in fig. 1 , can be closed, as in the case shown in fig. 1 and described here, or open. It is evident that the shape of the sliding track 11 defines the profile of the sliding path A.

[0051] The transport system 10 comprises a mobile unit or trolley, indicated with reference number 12, movable along the sliding track 11.

[0052] As will be clear below, the relative arrangement between the mobile trolley 12 and the sliding track 11 changes point-by-point, in particular in some portions of the sliding path A. For this reason, the sliding path A is defined as the trajectory followed by the geometric center of the mobile trolley 12.

[0053] In some variants of the transport system 10, a plurality of mobile trolleys 12 are provided, all sliding on the sliding track 11 in a reciprocally coordinated manner.

[0054] The mobile trolley comprises a rest plane 32 for the objects, which has been removed for reasons of clarity in the attached drawings 1-3 and 5-8, being schematically shown only in fig. 4. The rest plane 32 is substantially horizontal, in such a position as to be centered with respect to the sliding track 11. Preferably, the trace of a symmetry plane Y thereof passes through the underlying sliding track 11.

[0055] The mobile trolley 12 moves on the sliding track 11 between two or more operating stations, not shown, arranged along the sliding path A. Preferably, the mobile trolley 12 can move along the sliding track 11 in a bidirectional manner, as indicated by the arrow F in fig. 1.

[0056] The mobile trolley 12 comprises an upper wall 12a, oriented in such a way as to be horizontal and adjacent to the sliding track 11, immediately below the latter. The mobile trolley 12 also comprises a lower wall 12b, parallel to the upper wall 12a and connected to the latter by a connection wall 12c, arranged perpendicular to the upper 12a and lower 12b walls, in particular arranged vertically.

[0057] In the example given here, the mobile trolley 12 is shaped as a “C”, with the guide base 33 being received, at least in part, in the recess of the “C”, as visible in the section of fig. 4.

[0058] The mobile trolley 12 is moved along the sliding track 11 by means of drive means.

[0059] In the embodiment shown in particular in figs. 1 and 4, the transport system 10 comprises a linear motor 13 comprising primary windings 13a interacting with permanent magnets 13b to determine the movement of the mobile trolley 12 on the sliding track 11, by suitably controlling the electromagnetic field determined between them.

[0060] In particular, the linear motor 13 comprises a plurality of primary windings 13a, which are preferably distributed uniformly along the guide base 33. In particular, the primary windings 13a are arranged both on an upper surface 34 of the guide base 33, facing the upper wall 12a, and also on a lower surface 35 of the guide base 33, facing the lower wall 12b, as visible in the section of fig. 4. Furthermore, the linear motor 13 comprises at least one permanent magnet 13b, operatively associated with the mobile trolley 12, in particular housed in a suitable seating obtained in the trolley. Preferably, the shape of such seating is mating with the shape of the permanent magnet 13b. In the example given here, two permanent magnets 13b are associated with each mobile trolley 12, one arranged below its upper wall 12a and the other arranged above its lower wall 12b.

[0061] In any case, the movement of the mobile trolleys 12 is achieved, according to modes well known in the art, by selectively activating, according to a sequential progression, the primary windings 13 a. The electromagnetic field that is generated determines a movement of the mobile trolley 12, thanks to the interaction of the electromagnetic field with the permanent magnets 13b on board the trolley.

[0062] Although hereafter we will only refer to the use of linear motors, what described can also be applied to other types of transport systems, such as indexed-type chain or belt conveyors, etc., in which the mobile trolleys are moved stepwise.

[0063] The transport system 10 comprises an inner rolling guide 16 and an outer rolling guide 17, which develop along the sliding path A, configured to allow the movement of the mobile trolleys 12 on the sliding track 11.

[0064] The inner rolling guide 16 is arranged on an inner side 30 of the sliding track 11 , while the outer rolling guide 17 is arranged on an outer side 31 of the sliding track 11. In the example given, the sliding track 11 has a closed profile.

[0065] Each mobile trolley 12 comprises a first rolling unit 18 and a second rolling unit 19, cooperating with the inner and outer rolling guides 16, 17, respectively, in modes that will be described in greater detail below.

[0066] Each inner and outer rolling guide 16, 17 comprises respective inner and outer straight portions, indicated with reference numbers 16a, 17a, and respective inner and outer curved portions, indicated with reference numbers 16b, 17b.

[0067] The passage from a respective straight portion 16a, 17a to a respective curved portion 16b, 17b occurs at a respective transition portion, indicated by the numerical reference 16c, 17c (figs. 1-3), also referred to hereafter as “inner transition portion 16c” and “outer transition portion 17c”.

[0068] Furthermore, each inner and outer rolling guide 16, 17 comprises a pair of cams, each defining a respective rolling surface. Purely for the purposes of a clear disclosure, hereafter we will refer to the pair of cams comprised in the inner rolling guide 16 with the expressions “inner upper cam” and “inner lower cam”, indicated with reference numbers 20 and 21, respectively, while we will refer to the pair of cams comprised in the outer rolling guide 17 with the expressions “outer upper cam” and “outer lower cam”, indicated with reference numbers 22 and 23, respectively. Each one of these cams comprises a respective rolling surface: the inner upper cam 20 comprises an inner upper rolling surface 20a, the inner lower cam 21 comprises an inner lower rolling surface 21a, the outer upper cam 22 comprises an outer upper rolling surface 22a, and the outer lower cam 23 comprises an outer lower rolling surface 23 a. Preferably, the inner upper cam 20 is adjacent to the inner lower cam 21.

[0069] Preferably, the outer upper cam 22 is adjacent the outer lower cam 23. In the example shown here, the inner upper rolling surface 20a is opposite to and face the outer upper rolling surface 22a, and the inner lower rolling surface 21a is opposite to and face the outer lower rolling surface 23a. The inner and outer rolling guides 16, 17 are reciprocally distanced by a distance D, substantially equal to the width of the sliding track 11, measured along a segment perpendicular with respect to the inner and outer sides 30, 31.

[0070] Specifically, the distance D is the distance separating the inner upper rolling surface 20a from the outer upper rolling surface 22a, measured along a segment that point- by-point is perpendicular to two planes tangent to such surfaces at the measurement point.

[0071] Similarly, the inner lower rolling surface 21a is also distanced from the outer lower rolling surface 23a by the same distance D, measured along a segment that point-by-point is perpendicular to two planes tangent to such surfaces at the measurement point.

[0072] This distance D is substantially constant along the entire sliding path A, both whether it is measured between the upper cams 20, 22, and also whether it is measured between the lower cams 21, 23. The rolling surfaces 20a, 21a, 22a, 23a of the cams 20, 21, 22, 23 are arranged at respective rolling heights with respect to the sliding track 11. These rolling heights are indicated with the numerical references Hl, H2, H3 and H4 for, in order, the rolling surfaces 20a, 21a, 22a, 23a (see in particular figs. 5 and 6). The rolling heights H 1 , H2, H3 and H4 are measured as a distance to a respective fixed reference surface, shown with dashed lines in figs. 5 and 6, which identifies a plane passing through the central directrix placed in the center of the sliding track 11, taken along a segment perpendicular to the fixed reference surface. For example, this fixed reference surface can correspond to the symmetry plane Y, and coincide with the trajectory defined by the sliding path A followed by the geometric center of the mobile trolley 12.

[0073] In the example given here, the inner upper surface 20a and the outer upper surface 22a, which are parallel to each other along the entire sliding path A, have the same profile along the straight portions 16a, 17a and along the curved portions 16b, 17b, and are therefore arranged at the same rolling height Hl, H3 in such portions.

[0074] The inner lower surface 21a and the outer lower surface 23 a, which are parallel to each other along the entire sliding path A, have the same profile along the straight portions 16a, 17a and along the curved portions 16b, 17b, and are therefore arranged at the same rolling height H2, H4 in such portions.

[0075] In some embodiments, in the inner and outer transition portion, 16c, 17c, the first rolling height Hl of the inner upper rolling surface 20a can be approximately equal to the fourth rolling height H4 of the outer lower rolling surface 23 a, while the second rolling height H2 of the inner lower rolling surface 21a can be approximately equal to the third rolling height H3 of the outer upper rolling surface 23a.

[0076] In particular, the difference, in absolute value, between the value of the first and second rolling height Hl, H2, which have to be measured in an identical point of the sliding path, defines an inner cam profile deviation Si, better visible in the enlargements of figs. 5 and 6.

[0077] In a completely similar way, the difference, in absolute value, between the value of the third and fourth rolling height H3, H4, measured in an identical point of the sliding path, also defines an outer cam profile deviation Se, also better visible in the enlargements of figs. 5 and 6.

[0078] Hereafter in the present description, whenever reference is made to the inner Si or outer Se cam profile deviation, this is to be understood as measured with the heights of the two cams of the inner rolling guide 16, or the outer rolling guide 17, taken in the same point.

[0079] The first and second rolling height Hl , H2, as well as the third and fourth rolling height H3, H4, are arranged so that the cam profile deviation S has values that vary, in particular point-by -point, only when measured in the respective transition portion 16c, 17c. The trend of the inner Si and outer Se cam profile deviations is shown in the graph of fig. 5, in which it can clearly be seen that this parameter assumes a nonzero value only in the transition portions 16c, 17c.

[0080] In the example given here, the values of the inner cam profile deviation Si are greater than, for example about double, the values of the outer cam profile deviation Se, at least for a segment of the transition portions 16c, 17c.

[0081] As can be seen by comparing figs. 2 and 5 with figs. 3 and 6, in the example shown in the inner and outer transition portions 16c, 17c that the mobile trolley 12 will encounter first (at the top in figs. 2 and 3) the inner and outer upper cams 20, 22 have substantially the same profile when viewed from above (fig. 2), while in the section of fig. 3 the inner cam profile deviation Si and - although less accentuated because it is smaller in absolute value - the outer cam profile deviation Se are visible in a more accentuated manner; both deviations being better visible in the section of fig. 5. In the inner and outer transition portions 16c, 17c that the mobile trolley 12 will encounter second (at the bottom in figs. 2 and 3) the inner and outer upper cams 20, 22 have a conformation such that, in the top view (fig.

[0082] 2), the inner cam profile deviation Si and - although less accentuated because it is smaller in absolute value - the outer cam profile deviation Se are visible in a more accentuated manner; both deviations being better visible in the section of fig. 6.

[0083] Consequently, the inner rolling surfaces, respectively upper 20a and lower 21a, have a curvilinear profile different from each other in the inner transition portion

[0084] 16c. Similarly, also the outer rolling surfaces, respectively upper 22a and lower 23a, have a curvilinear profile different from each other in the outer transition portion 17c. Each of the inner rolling surfaces, respectively upper and lower 20a, 21a, and each of the outer rolling surfaces, respectively upper and lower 22a, 23 a, comprises respectively at least two inflection points, along the respective inner and outer transition portions 16c, 17c, clearly visible in the graph of fig. 5. At these points, the concavity of the rolling surfaces changes.

[0085] At a qualitative level, for one segment of the transition portions 16c, 17c the inner Si and outer Se cam profile deviations have a similar trend, in the remaining segment of the transition portions the inner Si and outer Se cam profile deviations have a similar gradient to each other, although offset in space. The first rolling unit 18 of the mobile trolley 12 comprises a first and a second rolling element 24, 25 configured, respectively, to roll over the inner upper and lower rolling surfaces 20a, 21a around respective first and second rolling axis, indicated with references XI and X2.

[0086] Similarly, the second rolling unit 19 of the mobile trolley 12 comprises a third and a fourth rolling element 26, 27 configured, respectively, to roll over the outer upper and lower rolling surfaces 22a, 23a around a respective third and fourth rolling axis, indicated with references X3 and X4.

[0087] Preferably, the first, second, third and fourth rolling axis, respectively XI, X2, X3 and X4, are parallel to each other, fixed, arranged substantially vertically, and perpendicular to the sliding path A.

[0088] In the embodiment shown, the first, second, third and fourth rolling elements 24, 25, 26, 27 are wheels rotatable around respective pins projecting upward from the upper wall 12a, but it is entirely clear that they can be configured as any rolling element whatsoever able to roll, such as for example wheels, rolls, rollers, of a known type or one that will be developed in the future.

[0089] The width of the respective rolling surfaces 20a, 21a, 22a, 23a is sized and conformed as a function of the size and shape of the respective rolling elements 24, 25, 26, 27 configured to roll thereon.

[0090] The first and third rolling elements 24, 26 are arranged at a raised vertical height, indicated with QI and Q3, respectively, which is higher than a lowered vertical height, indicated with Q2 and Q4, respectively, at which the second and fourth rolling elements 25, 27 are located (figs. 4-6). All the vertical heights, both raised and lowered, are measured starting from a reference plane in which the lower surfaces of the rolling elements 25, 27 lie (fig. 4).

[0091] It is evident that the upper rolling surfaces, respectively inner 20a and outer 22a, on which the first and third rolling elements 24, 26, respectively, roll are arranged at the raised vertical height QI, Q3.

[0092] Similarly, the lower rolling surfaces, respectively inner 21a and outer 23a, on which the second and fourth rolling elements 25, 27, respectively, roll are arranged at the lowered vertical height Q2, Q4.

[0093] Preferably, the raised vertical height QI , Q3 and the lowered vertical height Q2, Q4 are constant along the entire sliding path A.

[0094] Figs. 7 and 8, in which the cam profile deviations have been enlarged in an exaggerated manner for the benefit of clarity, show the interaction between the inner and outer rolling units 18 and 19 of the mobile trolley 12, with the inner and outer rolling guides 16, 17, respectively.

[0095] The choice of having different cam profiles in the inner and outer transition portion is due to the fact that, in this way, two rails are created (the upper rolling surface and the lower rolling surface) having a different profile from each other for the first and the second rolling element of the trolley. In particular, two rails are created on the inner side 30 and another two rails are created on the outer side 31.

[0096] In the inner transition portion 16c from the inner straight portion 16a to the inner curved portion 16b (inner side 30), the first rolling height Hl varies and is greater than the second rolling height H2, since the inner upper rolling surface 20a protrudes, with reference to the fixed reference surface, by an amount greater than the amount that the inner lower rolling surface 21a protrudes, with reference to the same reference surface, the inner lower rolling surface 21a being recessed inward, as shown with a dashed line. As mentioned, the difference in absolute value between the two heights Hl and H2 determines the inner cam profile deviation Si which - in the first transition portion 16c - is variable locally, that is, point-by- point.

[0097] In the outer transition portion 17c from the outer straight portion 17a to the outer curved portion 17b (second outer side 31), the third rolling height H3 varies and is smaller than the fourth rolling height H4, since the outer upper rolling surface 22a protrudes, with reference to the fixed reference surface, by an amount smaller than the amount that the outer lower rolling surface 23a protrudes, with reference to the same surface, the outer lower rolling surface 23 a being protruding outward, as shown with a dashed line. As mentioned, the difference in absolute value between the two heights H3 and H4 determines the outer cam profile deviation Se which - in the second transition portion 17c - is variable locally, that is, point-by-point. In other embodiments, that is, in transition portions with a different conformation from the one shown, the relative arrangement of the inner and outer rolling surfaces can also be interchanged, provided that one remains more protruding than the other, which instead remains more recessed.

[0098] The rolling heights of the four surfaces at the same vertical height are correlated in such a way that the sliding track always maintains a constant transverse width, equal to the distance D.

[0099] In particular, to a more protruding inner upper rolling surface 20a there correspond both an inner lower rolling surface 21a that is more recessed (Hl greater than H2), and also an outer upper rolling surface 22a that is more recessed than the outer lower rolling surface 23 a, which is more protruding (H4 greater than

[0100] H3).

[0101] Alternatively, to a more recessed inner upper rolling surface 20a there correspond both an inner lower rolling surface 21a that is more protruding (H2 greater than Hl), and also an outer upper rolling surface 22a that is more protruding than the outer lower rolling surface 23a, which is more protruding (H3 greater than H4).

[0102] It should be noted that the transport system 10 according to the present invention provides that in the inner straight portions 16a and in the inner curved portions 16b, the inner cam profile deviation Si between the inner upper and lower rolling surfaces 20a, 21a of the first and second cams 20, 21 is constant. Similarly, it is provided that in the outer straight portions 17a and outer curved portions 17b, the outer cam profile deviation Se is also constant between the upper and lower rolling surfaces 22a, 23a of the third and fourth cams 22, 23. In other words, the first and second cams 20, 21, as well as the third and fourth cams 22, 23, are configured and arranged in such a way that both the first and second rolling heights Hl, H2, and the aforementioned third and fourth rolling heights H3, H4, respectively, are invariable along the inner and outer straight portions 16a and 17a and along the inner and outer curved portions 16b and 17b. In this way, the inner cam profile deviation Si and the outer cam profile deviation Se are constant both in the inner and outer straight portions 16a, 17a and also in the inner and outer curved portions 16b, 17b, while at least one of either the first or second rolling height Hl, H2 and consequently at least one of either the third or fourth rolling height H3, H4 have a variable value along the respective inner and outer transition portions 16c, 17c, so that the inner and outer cam profile deviations Si and Se also have a variable value along these transition portions 16c, 17c, as shown in the graph of fig. 5.

[0103] According to a specific embodiment, in the inner and outer straight portions 16a, 17a and in the inner and outer curved portions 16b, 17b of the rolling guides 16,

[0104] 17, the rolling heights Hl, H2, H3 and H4 of the rolling surfaces 20a, 21a, 22a, 23a are the same as each other.

[0105] The geometrical arrangement of the rolling elements 24, 25, 26 and 27 means that a center distance I (figs. 2, 7 and 8) between the pair of rolling elements 24, 25 comprised in the inner rolling unit 18 is equal to a center distance I between the pair of rolling elements 26, 27 comprised in the outer rolling unit 19, as shown in fig. 2. These center distances are defined as the distance between the rolling axes XI -X2 and X3-X4 of the rolling elements 24-25 and 26-27.

[0106] The value of the inner Si and outer Se cam profile deviation in the transition portion 16c, 17c is proportionate to the center distance I, therefore as the center distance I increases, there will be a greater cam profile deviation S value, as well as a longer length of the transition portion 16c, 17c.

[0107] Advantageously, the transport system 10 according to the present invention allows to arrange the rolling elements 24, 25, 26 and 27 in such a way as to define center distances I which can reach values defined as desired, and which in general can reach values that are double or triple the center distances that typically characterize trolleys of this type known in the art, with the same radius of curvature of the sliding path. In addition, the transport system 10 according to the present invention allows to guarantee an anchoring of the mobile trolleys 12 to the sliding track 11 that is firm, resistant and whose coupling clearances between the rolling elements 24, 25, 26 and 27 and the inner and outer guides 16 and 17 remain constant in any segment that the trolleys travel along the path, in particular in the inner and outer transition portions 16c, 17c. It should be noted that the different conformation of the lower and upper rolling surfaces, and therefore the different rolling heights of the rolling surfaces, both at the inner side 30 and also at the outer side 31, determine inner Si and outer Se cam profiles deviations which, since they are variable point-by-point along the inner and outer transition portions 16c, 17c, define a variable advance inclination of the mobile trolley 12.

[0108] According to some embodiments, the transport system 10 according to the present invention can also comprise at least one position sensor, for example an encoder, not shown, which is configured to cooperate with the sliding track 11 to determine the position of the mobile trolley 12.

[0109] According to some variants, the transport system 10 provides that the rolling heights Hl and H2, as well as H3 and H4, are different from each other also in the inner and outer straight portions 16a, 17a and in the inner and outer curved portions 16b, 17b. In this case, to guarantee the correct sliding of the mobile trolley 12, the different rolling elements 24, 25, 26 and 27 can have different diameters from each other, suitably correlated to the profile of the respective rolling surfaces 20a, 21a, 22a, 23a on which they roll. Alternatively, or in combination with these variants, the different rolling elements 24, 25, 26 and 27 can all have the same diameter but the respective rolling axes XI, X2, X3 and X4 are each arranged at a suitable distance from the sliding track 11 , this distance being correlated to the profile of the rolling surfaces 20a, 21a, 22a, 23a on which the rolling elements 24, 25, 26 and 27 roll.

[0110] It is clear that modifications and / or additions of parts may be made to the transport system 10 as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

[0111] It is also clear that, although the present invention has been described with reference to some specific embodiment examples, a person of skill in the art will certainly be able to achieve many other equivalent forms of transport systems, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. In the following claims, the sole purpose of the reference numbers and symbols in brackets is to facilitate the reading of the claims and they must not be considered as restrictive factors with regard to the field of protection defined thereby.

Claims

CLAIMS1. Transport system (10) for transporting objects comprising:- a sliding track (11) having an inner side (30) and an outer side (31) opposite to and distanced from each other; - a mobile unit (12) movable on said sliding track (11) along a sliding path (A) having at least a curved path portion and at least a straight path portion;- drive means configured to move said mobile unit (12) on said sliding track (11); wherein said sliding track (11) comprises:- an inner rolling guide (16) on said inner side (30) of said sliding track (11), wherein said inner rolling guide (16) has at least one inner straight portion (16a), at least one inner curved portion (16b) and an inner transition portion (16c) interposed between the inner straight portion (16a) and the inner curved portion (16b), and wherein said inner rolling guide (16) comprises a first and a second cams (20, 21) having, respectively, an inner upper rolling surface (20a) and an adjacent inner lower rolling surface (21a); and- an outer rolling guide (17) on said outer side (31) of said sliding track (11), wherein said outer rolling guide (17) has at least one outer straight portion (17a), at least one outer curved portion (17b) and an outer transition portion (17c) interposed between the outer straight portion (17a) and the outer curved portion (17b), and wherein said outer rolling guide (17) comprises a third and a fourth cams (22, 23) having, respectively, an outer upper rolling surface (22a) and an adjacent outer lower rolling surface (23a), said inner upper rolling surface (20a) and said outer upper rolling surface (22a) being parallel to each other along the entire sliding path (A), and said inner lower rolling surface (21a) and said outer lower rolling surface (23a) being parallel to each other along the entire sliding path (A); and said mobile unit (12) comprises:- at least one inner rolling unit (18) configured to engage with said inner rolling guide (16), and comprising a first and a second rolling element (24, 25) which are configured, respectively, to roll over said inner upper and lower rolling surfaces(20a, 21a), said first and second rolling elements (24, 25) rotating around respective first and second rolling axis (XI, X2), which are parallel to and distant from each other,- an outer rolling unit (19) configured to engage with said outer rolling guide (17), comprising a third and a fourth rolling element (26, 27) which are configured, respectively, to roll over said outer upper and lower rolling surfaces (22a, 23 a), said third and fourth rolling elements (26, 27) rotating, respectively, around third and fourth rolling axis (X3, X4), wherein said first and third rolling elements (24, 26) are arranged opposite to each other, and said second and fourth rolling elements (25, 27) are arranged opposite to each other, and wherein on said inner transition portion (16c), said inner upper rolling surface (20a) follows a profile which is different from a profile followed by the inner lower rolling surface (21a), so as to define a varying inner cam profile deviation (Si) between the inner upper rolling surface (20a) and the inner lower rolling surface (21a), along said inner transition portion (16c), characterized in that said third and fourth rolling axis (X3, X4) are parallel to and distant from each other, wherein on said outer transition portion (17c), the outer upper rolling surface (22a) follows a profile which is different from a profile followed by the outer lower rolling surface (23 a), so as to define a varying outer cam profile deviation (Se) between the outer upper rolling surface (22a) and the outer lower rolling surface (23 a), along said outer transition portion (17c), such as to simultaneously maintain said first, second, third and fourth rolling element (24-27) in contact with the respective inner and outer transition portion (16c, 17c) during movement along the sliding track (11), and wherein a distance (D) between said inner upper rolling surface (20a) and said outer upper rolling surface (22a), as well as between said inner lower rolling surface (21a) and said outer lower rolling surface (23a) is invariable and remains constant along said inner and outer transition portions (16c, 17c), respectively; said distance (D) being measured perpendicular to a plane tangent point-by-point to the rolling surfaces.

2. System (10) as in claim 1, characterized in that said first, second, third and fourth rolling axis (XI, X2, X3, X4) are parallel to each other.

3. System (10) as in claim 1 or 2, characterized in that said first, second, third and fourth rolling axis (XI, X2, X3, X4) are perpendicular to the sliding path (A).

4. System (10) as in any claim hereinbefore, characterized in that said first, second, third and fourth rolling axis (XI, X2, X3, X4) are fixed.

5. System as in any claim hereinbefore, characterized in that said inner upper rolling surface (20a) is opposite to and face said outer upper rolling surface (22a) and in that said inner lower rolling surface (21a) is opposite to and face said outer lower rolling surface (23a).

6. System (10) as in any claim hereinbefore, characterized in that each of said inner rolling surfaces, respectively upper and lower (20a, 21a), and each of said outer rolling surfaces, respectively upper and lower (22a, 23a), respectively comprise two inflection points, along the respective inner and outer transition portion (16c, 17c).

7. System (10) as in any claim hereinbefore, characterized in that said drive means comprise a linear motor (13) comprising primary windings (13a) arranged on a fixed wall (34) and at least one permanent magnet (13b) housed in said mobile unit (12) and configured to interact with said primary windings (13a).

8. System (10) as in in any claim hereinbefore, characterized in that in said inner transition portion (16c), said inner upper and lower rolling surfaces (20a, 21a) are arranged at a respective first and second rolling height (Hl, H2) with respect to said sliding track (11), wherein the difference, in absolute value, between the value of said first and said second rolling height (Hl , H2) measured in an identical point of said inner transition portion (16c) defines said inner cam profile deviation (Si) having a punctually variable value, wherein said first and second rolling height (Hl, H2) are measured as distances to a fixed reference extending along a central directrix placed in the center of said sliding track (11), where said distances are taken along a segment perpendicular to said fixed reference.

9. System (10) as in in any claim hereinbefore, characterized in that in said outer transition portion (17c), said outer upper and lower rolling surfaces (22a, 23a) are arranged at a respective third and fourth rolling height (H3, H4) with respect to said sliding track (11), wherein the difference, in absolute value, between the value of said third and said fourth rolling height (H3, H4) measured in an identical point of said outer transition portion (17c) defines said outer cam profile deviation (Se) having a punctually variable value, wherein said third and fourth rolling height (H3, H4) are measured as distances to a fixed reference extending along a centraldirectrix placed in the center of said sliding track (11), where said distances are taken along a segment perpendicular to said fixed reference.

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