A conveyor device

Abstract

A conveyor device (101) comprising: an endless track which follows a track path in a transport direction, which track path comprises at least one straight section (203) and multiple curved sections in horizontal direction; a plurality of carriers (111); driving means formed by an electric linear synchronous motor drive system, comprising at least one stationary stator (401) mounted on at least one straight section (203) of said endless track, and a plurality of magnets (405) mounted in a row on each carrier (111) and arranged with alternating polarity, such that the magnets (405) of adjacent carriers (111) form a single straight row of magnets (405) when the carriers (111) move along said straight sections (203); wherein the conveyor device is arranged such that when said carriers (111) move from a curved section (201, 202) to a straight section (203) of said endless track the first outer magnet (407) at the first outer end of one carrier (111) moves towards the second outer magnet (408) at the second outer end of an adjacent carrier (111), such that along said straight section (203) a continuing row of magnets (405) with alternating polarities with equal mutual pitch and without interruptions is formed.

Description

[0001] A conveyor device

[0002] The present invention relates to a conveyor device comprising: an endless track forming a closed loop which follows a track path in a transport direction, which track path comprises at least one straight section and multiple curved sections in horizontal direction, wherein at least one of said curved sections forms a left curved section and at least one other one of said curved sections forms a right curved section;

[0003] a plurality of carriers distributed along said track, wherein each carrier comprises a rectangular support surface for carrying one or more objects;

[0004] driving means for moving said plurality of carriers along said track;

[0005] wherein said driving means are formed by a linear motor drive system, comprising at least one stationary stator mounted on at least one straight section of said endless track, and a plurality of magnets mounted in a row on each carrier and arranged with alternating polarity, such that the magnets of adjacent carriers form a single straight row of magnets when the carriers move along said straight sections;

[0006] wherein a first outer magnet of said plurality of magnets is positioned at a first outer end of each carrier and a second outer magnet of said plurality of magnets is positioned at a second outer end of each carrier, such that the first outer magnet at the first outer end of one carrier is adjacent to the second outer magnet at the second outer end of an adjacent carrier.

[0007] Conveyor devices, such as cross-belt sorters, are well known, for instance as disclosed in US 6,253,901 B1 and WO 2008 / 125121. An example of such a device is shown in and described with reference to Figs. 1A-C and Fig. 2. These conveyor devices may be used in sorter systems, wherein objects, such as packages which are to be sorted and sent to many different destinations, are transported from a loading or induction position to respective receiving positions. These receiving positions are usually located along the straight sections of the endless track, at both sides thereof, and usually are formed by chutes into which the objects are ejected. Each receiving position corresponds to a (group of) different destinations or clients. The curves in the track path preferably have a small radius in order to save space (i.e. to increase the length of the straight sections and to decrease the gap between the adjacent straight sections.

[0008] WO 2008 / 125121 describes a sorter wherein the driving means are formed by an electric linear synchronous motor drive system, and wherein the magnets are mounted on the carriers such that there is agap of one magnet pitch between the first outer magnet at the first outer end of one carrier and the second outer magnet at the second outer end of an adjacent carrier, at the location of the hinge connection between the carriers.

[0009] The goal of the invention is an improved conveyor device, in particular wherein the propulsion efficiency of the drive system is improved.

[0010] To this end, the conveyor device is arranged such that when said carriers move from a curved section to a straight section of said endless track the first outer magnet at the first outer end of one carrier moves towards the second outer magnet at the second outer end of an adjacent carrier, such that along said straight section a continuing row of magnets with alternating polarities with equal mutual pitch and without interruptions is formed.

[0011] The arrangement may be such that one, more or all of the magnets are movably mounted on the carrier, but in a preferred embodiment the magnets are fixed in a stationary position on the carriers, and the movement of the magnets is achieved for instance by one of the following preferred embodiments.

[0012] According to another embodiment, the carriers are mutually connected by releasable connection means at their centre between the left-hand side and the right-hand side, wherein the connection between the carriers is constructed such that if the releasable connection means is released, the distance between the carriers is allowed to increase to a maximum distance, and with means for re-establishing the respective connection after or when the carrier enters the straight section.

[0013] Said maximum distance is preferably such that in the sharpest curved section in the endless track the distance (yleft, xright) between the carriers at the side of the inside curved section is zero or almost zero.

[0014] The above-mentioned preferred embodiments are not mutually exclusive and are preferably combined. For instance, the embodiment wherein the carriers are arranged to contact and push each other, preferably with the mentioned bumpers, is preferably combined with embodiments wherein the carriers are mutually connected by connection means at the sides and / or in the centre, so that they are also arranged to pull each other.

[0015] Preferably, said distances dstraight, yleftand xrightbetween

[0016] the support surfaces are substantially equal.

[0017] According to another embodiment, the carriers are mutually connected by releasable connection means at their left-hand side and their right-hand side, and said conveyor device provided with means for releasing the connection between the carriers at the left-handside before or when the carrier enters a right curved section, and for releasing the connection between the carriers at the right-hand side before or when the carrier enters a left curved section, and with means for re-establishing the respective connection after or when the carrier leaves the respective curve.

[0018] The respective connections may for instance be a mechanical snap or latching connection, or a magnetic or electromagnetic connection, and the connections may be self-locking and -unlocking depending on changing pull / push forces between the carriers, or they may be actively locked and / or unlocked by means of activators before and / or after each curve.

[0019] Preferably, while moving along respectively said at least one straight section, said left curved sections and said right curved sections the carriers are in contact with each other at respectively both sides, the left-hand side, and the right-hand side.

[0020] In other words, in the preferred embodiment the construction of the device is such that two adjacent carriers always touch each other, whether they are moved along a straight section, a left curve or a right curve.

[0021] According to a preferred embodiment, each of said carriers is arranged to contact and push the adjacent carrier at its front side, wherein in the left curved sections the carriers contact and push each other at the left-side and in the right curved sections the carriers contact and push each other at the right-hand side.

[0022] Preferably, each carrier is provided with bumpers at the right hand side and the left hand side.

[0023] The bumpers may reduce the noise and wear when the carriers bump into each other, and furthermore the bumpers may be deformable by the force of the contact between the carriers.

[0024] Preferably, the releasable connection means comprise mechanical activator means for unlocking the respective connection at or before the start of each respective curve.

[0025] The releasable connection means may also comprise mechanical activator means for locking the respective connection at or after the end of each respective curve.

[0026] According to a preferred embodiment, the magnets are fixed in a stationary position in a row on the carriers, and the conveyor device is arranged such that when two adjacent carriers move from a curved section to a straight section of said endless track, said two adjacent carriers are allowed to move towards each other at one lateral side, such that along said straight section said continuing row of magnets with alternating polarities with equal mutual pitch and without interruptions is formed, and when said two adjacent carriers move from a straight section to a curved section of said endless track, said twoadjacent carriers are allowed to move away from each other at one lateral side to allow the carriers to move along the curved section.

[0027] According to an embodiment, the conveyor device is configured such that:

[0028] while moving along said at least one straight section the distance between adjacent sides of two adjacent support surfaces is dstraight; while moving along said left curved sections on the right-hand side the distance between adjacent corners of said support surfaces is xleftand on the left-hand side the distance between adjacent corners of said support surfaces is yleft; and

[0029] while moving along said right curved sections on the right-hand side the distance between adjacent corners of said support surfaces is xrightand on the left-hand side the distance between adjacent corners of said support surfaces is yright;

[0030] wherein said conveyor device is further configured such that while moving along said at least one straight section the distance between adjacent sides of two adjacent support surfaces is smaller than the average distance (yleft+ xleft) / 2 between the support surfaces while moving along said left curved sections and smaller than the average distance (xright+ yright) / 2 between the support surfaces while moving along said right curved sections.

[0031] Preferably, said releasable connection means comprise a latch mechanism with a latch to establish said connection and said mechanical activator means comprise a guide surface located along the endless track which pushes against the latch when the carrier passes said guide surface in order to unlock the latch and release said connection.

[0032] Preferably, said latch is spring loaded such that the latch automatically locks and re-establishes the respective connection when the carriers move along the straight sections of the endless track.

[0033] According to an especially preferred embodiment, said support surfaces are formed by top surfaces of a cross-belt conveyor.

[0034] In a cross-belt conveyor the support surfaces of each carrier are formed by the top surfaces of a small endless conveyor belt, whereby objects on the support surface can move from and be supplied to either side of the cross-belt conveyor.

[0035] According to an especially preferred embodiment, the conveyor device is a sorter device.

[0036] The present invention will now be illustrated with reference to the drawings, where

[0037] Figure 1A is a top perspective view of a straight section of a cross-belt conveyor device;

[0038] Figure IB is a bottom perspective view the straight section ofthe cross-belt conveyor device of Fig. 1A;

[0039] Figure 1C is a rear view of a part of the straight section of the cross-belt conveyor device of Fig. 1A;

[0040] Figure 2 is a schematic top view of the conveyor device comprising a straight section as shown in Fig. 1A;

[0041] Figure 3 is a schematic top view of an embodiment of a conveyor device in accordance with the invention;

[0042] Figure 4A is a top perspective view of a straight section of the cross-belt conveyor of Fig. 3;

[0043] Figure 4B is a top view of a section of a track of a straight section of the conveyor device of Fig. 3;

[0044] Figure 4C is a bottom perspective view of a carrier of the conveyor device of Fig. 3;

[0045] Figure 5A is a bottom view of reaction elements with magnets according to the prior art;

[0046] Figure 5B is a bottom view of reaction elements with magnets according to the invention;

[0047] Figure 6A is a top perspective view of a part of a first embodiment of a cross-belt conveyor device;

[0048] Figure 6B is a bottom view of the part of the first embodiment of a cross-belt conveyor device;

[0049] Figure 6C is a detailed top perspective view of the part of the first embodiment of a cross-belt conveyor device;

[0050] Figure 7A is a top perspective view of a part of a second embodiment of a cross-belt conveyor device;

[0051] Figure 7B is a bottom perspective view of the part of the second embodiment of a cross-belt conveyor device;

[0052] Figure 7C is a detailed bottom view of the part of the second embodiment of a cross-belt conveyor device;

[0053] Figure 8A is a top perspective view of a part of a third embodiment of a cross-belt conveyor device;

[0054] Figure 8B is a detailed bottom perspective view of the part of the third embodiment of a cross-belt conveyor device;

[0055] Figure 8C is a detailed side view of the part of the third embodiment of a cross-belt conveyor device in a latched state;

[0056] Figure 8D is a detailed perspective view of the part of the third embodiment of a cross-belt conveyor device in an unlatched state without a cross belt for better visibility; and

[0057] Figs. 9A and 9B are respective schematic top views of conveyor devices in accordance with Figs. 3 and 4 respectively.

[0058] With reference to Figs. 1A-C, a cross-belt sorter of the type as disclosed in US 6,253,901 B1 and WO 2008 / 125121, the disclosures of which are incorporated herein by reference, comprises a conveyor device 101. The conveyor device 101 comprises a base frame 110 whichcarries guide rails 114, 115, together forming a track of the conveyor device 101. A plurality of carriers 111 positioned consecutively in a conveying direction, flexibly connected to each other and forming an endless conveying line for loading of objects 104 on each of the carriers 111. Each carrier 111 at the central section of its front side 112 and the central section of its rear side 113 is pivotably connected to the adjacent carrier 111. A cross-belt conveyor is mounted at a top end of each carrier 111 for receiving and subsequent delivering of an object. The cross-belt conveyor has an endless-loop conveying belt 105 which runs over two rollers that are separately positioned and extend in the conveying direction of the conveyor device 101. The top surface 103 of the cross-belt conveying belt 105 forms a rectangular support surface. An electric motor drives one of the cross-belt rollers in such a manner that the support surface 103 of the cross-belt conveying belt 105 moves in the direction perpendicular to the transport direction toward a predetermined delivery station. Each carrier 111 may comprise a multitude of cross-belt conveyors, as shown in figures 4A, 4C, 9A and 9B.

[0059] Instead of cross-belt conveyors, tilt trays or trays with a pusher element may be used.

[0060] Each carrier 111 is supported and guided by means of the wheels 116 at its lower end section on left-hand side support / guide rail 114 and right-hand side support / guide rail 115, which determine an endless track path, as schematically shown in Fig. 2.

[0061] According to the invention said endless track path may have both left curved sections 201 and right curved sections 202, as well as straight sections 203. As shown in Fig. 2, the hingeable connection between the carriers 111 of the prior art as described above is designed such that it allows for the carriers 111 with the support surfaces 103 to take both the left curved sections 201 and the right curved sections 202, wherein the carriers 111 may touch each other at the side of the inner curved sections, while leaving a gap between the carriers 111 at the side of the outer curved sections. In the straight sections 203 there is a gap between the carriers 111 on both sides.

[0062] The conveyor has an electric linear synchronous motor drive system. A propulsion system for the conveyor comprises stationary stators 401 as shown in Fig. 4B, which has a coil assembly. In addition, as shown in Fig. 4C the carriers 111 have a reaction element 404 comprising a plurality of magnets 405 mounted on a ferromagnetic magnet carrier 406 thereby providing magnetic fields. A controller 402 controls the supply of electrical power to the coil assembly such that a travelling-wave magnetic field is generated which interacts with those of the magnets 405 to provide a driving force.

[0063] To that end the stators 401 are arranged in suitable positionsalong the track path. If the carriers 111 form an endless chain, it would in principle possible to provide the conveyor device with only one (group of) stator (s) 401 at one location along the track path. However, in order to enable a more smooth and constant propulsion, it is preferred to use a plurality of (grouped) stators 401 arranged along preferably multiple straight sections 203 of the track path.

[0064] A controller 402 is connected to an encoder 403 for determining a position and a speed of one or more carriers 111. The controller 402 controls the electrical power applied to the coil assembly of the stators 401 in response to the determined position and / or speed.

[0065] Preferably, the encoder 403 is placed in connection with a stator 401 such that when a position and / or a speed of a carrier 111 is detected, this is used to synchronize the travelling-wave magnetic field of the stator 401 with the magnetic fields of the magnets 405. The location determination can be used to set a phase of the frequency of the electrical supply creating the travelling-wave magnetic field, and the speed can be used to set the frequency of the electrical supply creating the travelling-wave magnetic field.

[0066] According to a prior art embodiment, as described disclosed in WO 2008 / 125121 Al, a reaction element 404 as shown in Fig. 5A comprises a plate-like magnet carrier 406 on which a plurality of permanent magnets 405 is fixed.

[0067] The magnets 405 are arranged with alternating polarity. The magnet 407 in one end of the reaction element and the magnet 408 in the opposite end have a magnetic north pole facing upwards. The number of magnets 405 on one reaction element is uneven. The uneven number of magnets 405 of a reaction element 404 from one end of said reaction element starts and ends with a magnetic north pole, but may as well start and end with a magnetic south pole. However, reaction elements on two adjacent carriers 111 must start and end with magnets having identical polarity.

[0068] Fig. 5A shows three consecutive magnetic reaction elements belonging to three consecutive carriers 111. Linking means 418 are indicated to illustrate that the carriers 111 are connected. The linking means 418 do not connect the carriers 111 by connecting the reaction elements 404, but instead connect one end of a carrier 111 with an end of an adjacent carrier 111.

[0069] The magnets 405 are arranged with a pitch from magnet to magnet. The magnets 405 on the reaction elements may be arranged with a pitch from magnet to magnet of 50 millimeters. The surface of the magnets 405, which is facing the stators 401, is square. The surface of the magnets has an extent of from 40 to less than 50 millimeters in a longitudinal direction of the carrier 111.

[0070] The reaction elements 404 are attached to the carriers. Theplate-like magnet carrier 406 may be arranged in a horizontal position on the carriers 111 and the stationary stators 401 are arranged to interact with the reaction elements 404 from a position below the reaction elements 404 when the stator 401 and reaction elements 404 are interacting to propel the carriers 111.

[0071] Alternatively, the magnet carriers 406 may be arranged in a vertical position on the carriers 111. The stationary stators will then be arranged to interact with the reaction elements 404 from positions situated sideways to said reaction elements 404 when the stators 401 and the reaction elements 404 are interacting. In that case, the stators 401 are arranged in pairs acting from opposite sides in order to counterbalance forces induced on the reaction elements 404.

[0072] The uneven number of magnets 405 on the reaction element 404 is shown as starting with a magnetic north pole at the first magnet 407 and ending with a magnetic north pole at the last magnet 408. The first magnet 407 on an adjacent reaction element 404 belonging to a not shown adjacent carrier 111 has the same polarity as the last magnet 408 on the reaction element 404. The distance between the last magnet 408 and the first magnet of an adjacent carrier 111 is chosen as twice the magnet to magnet pitch in order that the magnets 405 of the adjacent reaction elements form a row with alternating polarity and constant pitch from magnet to magnet. A magnet is absent in the row at the transition between the carriers by the position indicated in dotted lines around linking means 418, where a magnetic south pole could have been present.

[0073] When the magnets 405 on reaction elements on adjacent or consecutive carriers 111 have identically alternating polarities, i. e. either starting and ending with a magnetic north pole or starting and ending with a magnetic south pole, the magnets may be arranged to form a continuing row of alternating polarities, said row having an interruption where a magnet 405 is absent.

[0074] According to an embodiment according to the invention as shown in Fig. 5B, the permanent magnets 405 of adjacent carriers 111 are arranged to form, when they travel along the straight sections 203 of the track path, a continuing row of alternating polarities, said row having no interruptions where a magnet 405 would be absent.

[0075] To that end, the magnet 407 at one end of the reaction element 404 of one carrier 111 and the adjacent magnet 408 at the opposite end of an adjacent carrier 111, which are spaced apart in the curved sections 201, 202 of the track path, are moved towards each other when the carriers 111 enter the straight sections 202 of the track path, such that the gap between adjacent magnets 407, 408 is substantially equal to the gap between the other magnets 405, and are moved apartwhen the carriers 111 enter the curved sections 201, 202 of the track path.

[0076] Like the prior art embodiment shown in Fig. 5A, the reaction element 404 comprises a plate-like magnet carrier 406 on which a plurality of magnets 405 is fixed. Fig. 5B shows three consecutive magnetic reaction elements 404 belonging to three consecutive carriers 111.

[0077] The magnets 405 are arranged with alternating polarity. As shown in Fig. 5B, the number of magnets 405 on one reaction element may be uneven, in which case the magnet 407 in one end of the reaction element and the magnet 408 in the opposite end may both have a magnetic north pole facing either upwards or downwards. The uneven number of magnets 405 of a reaction element 404 from one end of said reaction element may thus start and end with a magnetic north pole, but may as well start and end with a magnetic south pole. However, reaction elements 404 on two adjacent carriers 111 must start and end with magnets having opposite polarities.

[0078] In an alternative embodiment the number of magnets 405 on a reaction element 404 is even, and the magnet 407 in one end of the reaction element 404 and the magnet 408 in the opposite end of the reaction element 404 have opposite polarities.

[0079] The magnets 405 are arranged with a pitch from magnet to magnet. The magnets 405 on the reaction elements 404 may be arranged with a pitch from magnet to magnet of for instance 50 millimeters. The surface of the magnets 405, which is facing the stators 401, is preferably square. The surface of the magnets may have an extent of from 40 to less than 50 millimeters in a longitudinal direction of the carrier 111.

[0080] The reaction elements 404 are attached to the carriers 111. The plate-like magnet carrier 406 may be arranged in a horizontal position on the carriers 111 and the stationary stators 401 are arranged to interact with the reaction elements 404 from a position below the reaction elements 404 when the stator 401 and reaction elements 404 are interacting to propel the carriers 111.

[0081] Alternatively, the magnet carriers 406 may be arranged in a vertical position on the carriers 111. The stationary stators will then be arranged to interact with the reaction elements 404 from positions situated sideways to said reaction elements 404 when the stators 401 and the reaction elements 404 are interacting. In that case, the stators 401 are arranged in pairs acting from opposite sides in order to counterbalance forces induced on the reaction elements 404.

[0082] According to the invention, a maximum number of coils in the stator 401 may be active at the same time to interact with the magnets405, and the maximum amount of propulsion power is transferred to the carriers 111.

[0083] According to an embodiment of the invention as shown in Fig. 3, in order to move the magnet 407 at one end of the reaction element 404 of one carrier 111 and the adjacent magnet 408 at the opposite end of an adjacent carrier 111 towards each other when the carriers 111 enter the straight sections 202 of the track path, the driving system and / or the connection means between the carriers 111 is designed such, that in the straight sections 203 of the endless track the distance between the carriers 111 is at least smaller than as shown in Fig. 2, and, as shown in Fig. 3, in a preferred embodiment there is no distance between the carriers 111 in the straight sections 203 at all.

[0084] According to a first practical embodiment as shown in Figs. 6A-C, each carrier 111 is arranged to contact and push the adjacent carrier at its front side 112. In the left curved sections 201 the carriers contact and push each other at the left-side and in the right curved sections 202 the carriers contact and push each other at the

[0085] right-hand side. In the straight sections 203 the carriers 111 contact and push each other at both sides.

[0086] To make contact, each carrier 111 is provided with resilient bumpers 601 at the right-hand side and the left-hand side. The bumpers 601 are deformable by the force of the contact between the carriers 111 and act as shock absorbers.

[0087] One or more driving units may drive the carriers 111 forward at one or more driving locations along straight sections 203 of the endless track, such that the driven carrier 111 at said driving locations will push the carriers 111 in front of it forward.

[0088] According to a second practical embodiment as shown in Figs.

[0089] 7A-C, the carriers 111 are mutually connected by releasable connection means at their left-hand side and their right-hand side. The connection means on each side may comprise a latch 701 on the front side 112 of the carrier 111, which latch 701 may be a lever which is pivotable around a vertical shaft 710, and which is provided with a hook 702 on one outer end and a pin or wheel 703 on the other outer end. The hook 702 engages a pin 704 on the rear side 113 of the adjacent carrier 111. The latch 701 is spring loaded such that the latch automatically locks.

[0090] An unlocking guide surface 705 is provided on the respective rail 114, 115 at the location of the start of the outer curved sections, which guide surface 705 engages the pin or rotating wheel 703 of the latch of each passing carrier, such that it forces to rotate the lever and release the hook 702 from the pin 704, thereby releasing the connection between the carriers 111 at the side of the outer curved sections.Since the latch 701 is spring loaded the latch 701 automatically locks and re-establishes the respective connection when the carriers 111 enters the straight sections 203 of the endless track.

[0091] According to a third practical embodiment as shown in Figs. 8A-D, the carriers 111 are mutually connected by releasable connection means at their centre, between the left-hand side and the right-hand side.

[0092] The connection between the carriers 111 is provided by a sliding rod 811, which is fixedly connected in longitudinal direction to the front side 112 of each carrier 111, and which extend through, a slider ball joint 812 in an upright wall 813 at the rear side 113 of the adjacent carrier 111. The rod 811 is allowed to slide through said ball joint 812 in the longitudinal direction. The outer end of the rod 811 is provided with a widened stopper 814 which abuts against the inner side of the slider ball joint 812, when the rod 811 is pulled backwards through the slider ball joint 812 relative to the wall 813, as shown in Fig. 6D.

[0093] The outer end of the rod 811 is furthermore provided with a pin 804, for engagement by a hook 802.

[0094] The connection means furthermore may comprise a latch 801 at the centre of the carrier 111, which latch 801 may be a lever which is pivotable around a horizontal shaft 810, and which is provided with a hook 802 on one outer end and a pin or wheel 803 on the other outer end. The hook 802 engages the pin 804 on the outer end of the rod 811 of the adjacent carrier 111. The latch 801 is spring loaded such that the latch automatically locks.

[0095] An unlocking guide surface 805 is fixed between the rails 114, 115 at the location of the start of the curved sections, which guide surface 805 engages the pin or wheel 803 of the latch of each passing carrier, such that it forces to rotate the lever and release the hook 802 from the pin 804, thereby releasing the fixed connection between the carriers 111.

[0096] The connection between the carriers 111 is thereby constructed such, that if the connection is released by unlocking the latch 801, the distance between the carriers is allowed to increase from a minimum distance as shown in Fig. 8C to a maximum distance in the curved sections as shown in Fig. 8D, and the carriers 111 can pull the adjacent carrier 111 through the curved section.

[0097] Since the latch 801 is spring loaded the latch 801 automatically locks and re-establishes the fixed connection with the rods 811 when the carriers 111 move along the straight sections 203 of the endless track.

[0098] Reference is made to Figs. 9A and 9B. In prior art devices with left and right curved sections, as shown in Fig. 9A, the carriers are mutually connected in the centre and the distance (dstraight) betweenthe support surfaces in the straight sections is the average of the distances between the support surfaces in the curved sections, in other words: dstraight= (xleft+ yleft) / 2 = (xright+ yright) / 2.

[0099] According to the embodiment as shown in Fig. 9B, the device is constructed such that the distance (dstraight) between the support surfaces in the straight sections is substantially smaller than the average distances (xleft+ yleft) / 2 and (xright+ yright) / 2

[0100] between the support surfaces in the curved sections. Thereby, in the straight sections of the track more carriers, and thereby more support surfaces, can be accommodated than in the prior art devices. In the configurations as shown in Figs. 2 and 3 the capacity of the conveyor device according to the invention as shown in Fig. 3 ( 179 carriers ) is increased by 14 % compared to the prior art conveyor device as shown in Fig. 2 ( 157 carriers ).

[0101] Other prior art devices, which only comprise straight track parts and curved section track parts with either only left curved sections or only right curved sections, comprise carriers which are mutually connected at the inner side of the curved sections, such that the distance (dstraight) between the support surfaces in the straight sections is also substantially smaller than the average distances (xleft+ yleft) / 2 and (xright+ yright) / 2 between the support

[0102] surfaces in the curved sections. According to the embodiments described herein this principle can be carried over to tracks which have both left curved sections and right curved sections.

[0103] It should be noted that, where reference is made to a " rectangular support surface", that this does not necessarily mean that the rectangular support surface is formed and delimited by a rectangular top side of the carrier. The rectangular support surface in this respect may also be a rectangular area within a differently shaped top side of the carrier. Furthermore, a " rectangular support surface" may also be composed of more than one support surfaces on one carrier (as shown for instance in Figs. 9A and 9B).

[0104] It should furthermore be noted, that where reference is made to " left", " right", " front" and " rear", this is seen in the transport direction as indicated by the arrows in Figs. 2 and 3.

[0105] The invention has thus been described by means of preferred embodiments. It is to be understood, however, that this disclosure is merely illustrative. Various details of the structure and function were presented, but changes made therein, to the full extent extended by the general meaning of the terms in which the appended claims are expressed, are understood to be within the principle of the present invention. The description and drawings shall be used to interpret the claims. The claims should not be interpreted as meaning that the extent of the protection sought is to be understood as that defined bythe strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. For the purpose of determining the extent of protection sought by the claims, due account shall be taken of any element which is equivalent to an element specified therein. An element is to be considered equivalent to an element specified in the claims at least if said element performs substantially the same function in substantially the same way to yield substantially the same result as the element specified in the claims.

Claims

C L A I M S1. A conveyor device ( 101 ) compri sing:an endle s s t rack forming a closed loop which follows a t rack path in a t ransport direct ion, which t rack path compri se s at least one straight sect ion ( 203 ) and mult iple curved sect ions in hori zontal direct ion, wherein at least one of said curved sect ions forms a left curved sect ion ( 201 ) and at least one other one of said curved sect ions forms a right curved section ( 202 );a plurality of carriers ( 111 ) di st ributed along said track, wherein each carrier ( 111 ) compri se s a rectangular support surface ( 103 ) for carrying one or more ob ject s;driving means for moving said plurality of carriers ( 111 ) along said t rack;wherein said driving means are formed by a linear motor drive system, compri s ing at least one stat ionary stator ( 401 ) mounted on at least one st raight sect ion ( 203 ) of said endle s s track, and a plurality of magnet s ( 405 ) mounted in a row on each carrier ( 111 ) and arranged with alternat ing polarity, such that the magnet s ( 405 ) of adj acent carriers ( 111 ) form a s ingle st raight row of magnet s ( 405 ) when the carriers ( 111 ) move along said straight sect ions ( 203 );wherein a first outer magnet ( 407 ) of said plurality of magnet s ( 405 ) i s pos it ioned at a first outer end of each carrier ( 111 ) and a second outer magnet ( 408 ) of said plurality of magnet s ( 405 ) i s pos it ioned at a second outer end of each carrier ( 111 ), such that the first outer magnet ( 407 ) at the first outer end of one carrier ( 111 ) i s adj acent to the second outer magnet ( 408 ) at the second outer end of an adj acent carrier ( 111 ); wherein the conveyor device i s arranged such that when said carriers ( 111 ) move from a curved section ( 201, 202 ) to a st raight sect ion ( 203 ) of said endle s s track the first outer magnet ( 407 ) at the first outer end of one carrier ( 111 ) move s towards the second outer magnet ( 408 ) at the second outer end of an adj acent carrier ( 111 ), such that along said st raight sect ion ( 203 ) a cont inuing row of magnet s ( 405 ) with alternat ing polarit ies with equal mutual pitch and without interruptions i s formed.

2. The conveyor device ( 101 ) according to claim 1, wherein the carriers ( 111 ) are mutually connected by releasable connect ion means at their cent re between the le ft-hand s ide and the right-hand s ide, wherein the connect ion between the carriers ( 111 ) i s constructed such that i f the releasable connect ion means i s released, the di stance between the carriers ( 111 ) i s allowed to increase to a maximum distance, and with means for re-e stabli shing the re spect ive connect ion after or when the carrier ( 111 ) enters the st raight sect ion ( 203 ).

3. The conveyor device ( 101 ) according to claim 10, wherein said distance s dstraight, yleftand xrightbetween the support surface s( 103 ) are substantially equal.

4. The conveyor device ( 101 ) according to any of the claims 3, 5, 6, 7, 9 and 10, wherein the carriers ( 111 ) are mutually connected by releasable connection means at their le ft-hand s ide and their right-hand s ide, and said conveyor device ( 101 ) provided with means for releasing the connect ion between the carriers ( 111 ) at the left-hand s ide be fore or when the carrier ( 111 ) enters a right curved sect ion ( 203 ), and for releas ing the connect ion between the carriers ( 111 ) at the right-hand s ide be fore or when the carrier ( 111 ) enters a left curved sect ion ( 203 ), and with means for re-establi shing the respect ive connection after or when the carrier ( 111 ) leave s the respect ive curve.

5. The conveyor device ( 101 ) according to any of the claims 3, 9 and 10, wherein while moving along re spect ively said at least one st raight sect ion ( 203 ), said le ft curved sect ions ( 201 ) and said right curved sect ions ( 202 ) the carriers ( 111 ) are in contact with each other at respect ively both s ide s, the le ft-hand s ide, and the right-hand s ide.

6. The conveyor device ( 101 ) according to any of the claims 3, 5, 9 and 10, wherein each of said carriers ( 111 ) i s arranged to contact and push the adj acent carrier ( 111 ) at it s front s ide ( 112 ), wherein in the le ft curved sect ions ( 201 ) the carriers ( 111 ) contact and push each other at the le ft-s ide and in the right curved sect ions ( 202 ) the carriers ( 111 ) contact and push each other at the right-hand s ide.

7. The conveyor device ( 101 ) according to any of the claims 3, 5, 6, 9 and 10, wherein each carrier ( 111 ) i s provided with bumpers ( 601 ) at the right hand s ide and the le ft hand s ide.

8. The conveyor device ( 101 ) according to claim 2 or 4, wherein the releasable connection means comprise mechanical act ivator means for unlocking the re spect ive connect ion at or be fore the start of each respect ive curve.

9. The conveyor device ( 101 ) according to any of the preceding claims, wherein the magnet s ( 405 ) are fixed in a stat ionary pos it ion in a row on the carriers, and the conveyor device is arranged such that when two adj acent carriers ( 111 ) move from a curved sect ion ( 201, 202 ) to a straight sect ion ( 203 ) of said endle s s t rack, said two adjacentcarriers (111 ) are allowed to move towards each other at one lateral side, such that along said straight section (203 ) said continuing row of magnets ( 405 ) with alternating polarities with equal mutual pitch and without interruptions is formed, and when said two adjacent carriers move from a straight section (203 ) to a curved section (201, 202 ) of said endless track, said two adjacent carriers ( 111 ) are allowed to move away from each other at one lateral side to allow the carriers (111 ) to move along the curved section.

10. The conveyor device ( 101 ) according to any of the preceding claims, wherein the conveyor device ( 101 ) is configured such that: while moving along said at least one straight section (203 ) the distance between adjacent sides of two adjacent support surfaces (103 ) is dstraight;while moving along said left curved sections (201 ) on the right-hand side the distance between adjacent corners of said support surfaces (103 ) is xleftand on the left-hand side the distance between adjacent corners of said support surfaces ( 103 ) is yleft; and while moving along said right curved sections (202 ) on the right-hand side the distance between adjacent corners of said support surfaces (103 ) is xrightand on the left-hand side the distance between adjacent corners of said support surfaces ( 103 ) is yright; wherein said conveyor device ( 101 ) is further configured such that while moving along said at least one straight section (203 ) the distance dstraightbetween adjacent sides of two adjacent support surfaces (103 ) is smaller than the average distance (yleft+xleft) / 2 between the support surfaces ( 103 ) while moving along said left curved sections (201 ) and smaller than the average distance (xright+ yright) / 2 between the support surfaces ( 103 ) while moving along said right curved sections (202 ).

11. The conveyor device ( 101 ) according to any of the claims 2 to 10, wherein said releasable connection means comprise a latch mechanism with a latch to establish said connection and said mechanical activator means comprise a guide surface located along the endless track which pushes against the latch when the carrier ( 111 ) passes said guide surface in order to unlock the latch and release said connection.

12. The conveyor device ( 101 ) according to claim 11, wherein said latch is spring loaded such that the latch automatically locks and re-establishes the respective connection when the carriers ( 111 ) move along the straight sections (203 ) of the endless track.

13. The conveyor device ( 101 ) according to any of the preceding claims, wherein said support surface s ( 103 ) are formed by top surface s ( 103 ) of a cros s-belt ( 105 ) conveyor.

14. The conveyor device ( 101 ) according to any of the preceding claims, wherein the conveyor device ( 101 ) i s a sorter device ( 101 ).

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