Abstract:
A sorter conveyor having laterally tiltable transport trays, instead of comprising a conventional transport chain driven by a driving station, in which a driving wheel or worm cooperates with the chain links, these being advanced arranged with guiding rails along a small mutual spacing and carrying both the transport trays and the tilt mechanisms associated therewith, which conventional arrangement causes considerable problems with respect to tolerances for both the longitudinal pitch of the chain links and the mounting of the guiding rails, comprises carts that are advanced along mutually widely spaced guiding rails (2), whereby the tolerance demands on the latter are reduced considerably; the carts are advanced by way of stationary linear motors (26), which renders any tolerance demands on the longitudinal pitch of the tray units entirely superfluous. Also the tilting mechanisms may be given a very simple design.

Description:
This is a continuation of application Ser. No. 08/155,232 filed Nov. 22, 1993 which is in turn a continuation of application. Ser. No. No. 07/994,292, filed Dec. 21, 1992 which in turn is a continuation of application Ser. No. 07/752,664 filed Aug. 26, 1991, each of which prior applications is now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a sorting conveyor including an annular row of laterally tiltable carrier platforms, which, on movable supports, are conveyed past a loading station, in which articles to be sorted are placed on the carrier platforms or so-called trays, and past a row of unloading or receiving stations, in which the trays are actuated selectively for tilting off and unloading the articles. 
     Conventional trays are driven by way of a driving station cooperating with a chain, to which the supports of the trays being secured, to a very heavy chain, the links of which are fitted with protruding guiding rollers that cooperate with longitudinal guiding rails, such that it is the chain itself which constitutes a stabilized base for the tray supports. This arrangement requires a guiding system made with very fine tolerances if unfortunate jammings and shakings should be avoided, moreover, the chain itself should be made with fine tolerances for a current, untroubled cooperation with the driving station. There are extra demands on the chain construction if the chain is to move through both horizontal and vertical curves, because the chain links should then be mutually movable in more directions while maintaining narrow tolerances. On the other hand it will then be possible, by for example a tachometer sensing at a single place of the conveyor path, to keep control with the exact positionings of all the trays in the system, such that the actuator means for the tilting of the trays in the single unloading stations can be activated by the passage of just the respective relevant trays. 
     SUMMARY OF THE INVENTION 
     It is the purpose of the invention to provide a new construction of a sorting conveyor of the type described above by which several important advantages will be obtainable. 
     A main aspect of the invention is that the principle of effecting the drive of the conveyor by cooperation between a local driving station and a driven conveyor chain is eliminated, an instead the single tray elements with associated supports form cart units that are driven along a carrier chassis based on the use of linear motors evenly distributed along the chassis, with the single cart units being provided with marker means that are selectively detectable in the unloading stations. 
     This concept offers a number of important advantages. The single units may well be said to constitute links in a chain, but the units, as carts, may cooperate with a guiding chassis, which can have widely separated guiding rails and, for that reason, can be designed without the fine tolerances as required for conveyor chains, if they shall be advanced without jamming and without shakings or undue wear. Also the carts themselves can be built with rather coarse tolerances, particularly with respect to their length dimension; It is a characteristic of a chain driven by a driving station that the chain should have a constant and rather accurate pitch, but in connection with the invention it is without any operative significance whether the carts are even approximately of uniform lengths. In principle the carts need not even be intercoupled, when only the linear motor equipment is suitably widespread to be able to steadily serve the carts. However, it is very simple to provide for an intercoupling between the carts, since a both simple and very suitable coupling can be constituted by a central ball head connection, which will enable the coupled carts to carry out mutual turns in all possible directions. This is important when driving through horizontal and/or vertical curves, and it should be under emphasized that with intercoupled carts each cart will have to be provided with driving rollers only at its front or rear end, while the opposite end can just be centrally turnably connected with the roller carrying end of the cart to which it is coupled. Hereby the carts may also pass through twisted portions of the chassis, e.g. when the carts are moved into a laterally inclined position for running through horizontal curves, this making an operation at quite high speed possible; However the trays may be tilted into a suitably inclined position along such curves, without the carts having to be tilted. 
     The carts will be very easy to remove one by one should they need to be replaced, and it will be possible to make use of carts with different lengths. 
     The term &#34;linear motor&#34; should be understood in a wide sense, but typically the motors will be of the travelling field type, which is usually designated by this term. Preferably use is made of a plurality of such motors with an even distribution along the conveyor track, and of course the carts should be provided with parts such as longitudinally extending rail portions of aluminium for cooperation with the motors. With the use of carts that are not coupled together the motors should be located with sufficiently small spacing to ensure that each cart train will steadily be in driving connection with at least one motor. It may well be presumed that the moved carts due to their inertia will be able to move a long distance between two motors or motor areas, but at each start of the system, preferably, all cart trains should be able to start no matter in which positions they have been stopped. 
     The invention implies significant consequences for the manner in which the entire system can be controlled, but that is dealt with in more detail in a parallel patent application. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following the invention is explained in more detail with reference to the drawing, in which: 
     FIG. 1 is a perspective partial view of a sorter conveyor according to the invention, 
     FIG. 2 is a perspective view of an embodiment of a cart in the sorter a conveyor of FIG. 1. 
     FIG. 3-5 are different views of an associated tilting mechanism, and 
     FIGS. 6-7 are top and side views, respectively, of an actuation arrangement for the tilting mechanism. 
    
    
     DETAILED DESCRIPTION 
     The conveyor shown in FIG. 1 has a rigid chassis with two parallel guiding rails 2 mounted with a substantial mutual spacing, e.g. by 60 cm. Between the rails is arranged a row of carts 4 each having an upper tray 6. Each cart includes of a traverse 8 having outer driving wheels 10, which can roll in substantially C-profiled rails 2, and a carrier portion 12 that projects forwardly or rearwardly from the traverse 8. The carrier portion 12, at its opposite end is turnably coupled together with the following or the preceding cart. On the carrier portion 12 is provided a top structure 16 tiltably supporting the tray 6, which is secured to a carrier plate 18 at the top of a depending rod 20 fastened in a pivot bearing to the structure 16. Hereby the trays 6 may be tilted by a suitable lateral displacing of the lower ends of the rods 20. It should be mentioned, however, that this arrangement is shown only as an illustrative example, as it will have certain drawbacks in certain applications of the conveyor. 
     A longitudinally extending aluminum plate 24&#39;, cooperable with linear motors 26, is provided on the transverse 8 with the linear motors 26 being arranged locally along the guiding rails 2. Hereby the carts or the train of carts can be advanced without the use of any other form of fixed driving station, i.e. the carts should not be designed with accurately positioned parts for mechanical engagement with driving means of such a station. 
     In FIG. 2 is shown a more suitable embodiment, in which an aluminium plate 24 is mounted as a horizontal bottom plate underneath the central carrier portion 12, such that the linear motors 26 may effect driving centrally on the carts. The actuator rods 20 cannot then be depending underneath the middle area of the carts, but they can be placed pairwise adjacent respective opposite sides of the carts for tilting actuation of the trays 6 to one side and the other, respectively. FIG. 2 also shows in more detail that the free end of the central carrier portion is provided with a coupling head 28 to be coupled together with a ball head 30 of the neighboring cart. 
     FIGS. 3-5 show a preferred design of the tilting mechanism. On a rigid bracket 32 is mounted a single tilting body 36 having at its top a crosswise extending arm 60, which is at either end provided with a pivot bearing 62 carrying a depending pivot arm 64, which at its lower end is provided with a laterally projecting cam follower roller 66. At either side of the bracket is mounted a pair of parallel plates 68 each provided with guiding tracks 70 cooperating with rollers 72 on a cross shaft pin 74 approximately midway on the arm 64. Each of the tracks 70 has a lower portion 76 shaped with a lowermost, inwardly directed track portion 78 and with an uppermost, correspondingly inwardly directed track portion 80, which continues further upwardly in an upper track portion 82. 
     As shown in FIG. 3 and 4 the depending pivot arms 64 assume a normal position with the rollers 72 located adjacent to the innermost end of the intermediary track portions 80, whereby they are held in an associated, slightly inwardly inclined position by the action of a drawspring 83 interposed between the arms 64. The spring 83 permanently seeks to swing the lower ends of the arms inwardly. In these positions, the rollers 72 cannot be moved downwardly, i.e. the tilting mechanism will be locked against tilting to either side. 
     An actual tilting will be enabled by a selected lower cam follower roller 66 (FIG. 4), FIG. 4 being pulled outwardly and thereafter downwardly as shown in FIG. 5. When pulled outwardly the rollers 72, by the associated outward tilting of the arm 64, will be moved outwardly in the track portions 80 into a position adjacent the upper end of the lower track portions 76, such that these will thereafter, when guided down along the track portions 76, allow the arm 64 to be pulled downwardly for effecting tilting of the tilting body 36 and its associated, non-illustrated tray. During this, the rollers 72 on the opposite arm 64 will be moved upwardly through the upper track portions 82, thereby this arm can be held swung inwardly in a roughly unchanged angular position, and it will thus be ensured that its rollers 72 will be returned safely to the initial position by the following swinging down. In the right hand side--the arm 64 will be forced to swing inwardly during the very final phase of the drawing down, viz. by introduction of the rollers 72 into the the lower track end 78, this being shown in full lines in FIG. 7. Besides, all this will not normally be a question of a pulling down, but rather of a pressing down, because the conveyor tray and the load resting thereon will get the common point of gravity moved outwardly by the tilting, whereby the tilting will be positively supported. 
     For the pulling down of the roller 66 the illustrated fixed inclined rail 84 at the inside of the chassis bed 2 is used. According to FIG. 4, however, the roller 66 in its normal position will be located somewhat inside of the rail 84, such that normally a free passage of the units at the selected unloading station (FIG. 1) will be ensured, and it will be understood that an actuation of the unloading station it will require the outward tilting of the arm 64. For achieving that result there is mounted adjacent the foremost upper end of the rail 84, an L-profiled rail portion 86 having an inner upstanding flange 88, and--as shown in dotted lines in FIG. 3--assuming a normal position in straight continuation of the rail 84 and thus outside the path of movement of the roller 66. The L-profiled member 86 is pivotally connected with the front end of the lower flange of the rail 84, such that it is pivotable into the position shown in full lines in FIG. 3, in which its front end is located inside the path of movement of the roller area 66, such that this roller when passing the area, will hit contact the upstanding flange 88 and thus be forced to move into contact with the rail 84. The L-profiled member 86 is prolonged at the other side of its pivot connection with the rail 84, whereby the upstanding flange portion at this end will be swung closely towards the vertical wall of the rail 84. Thus, this wall may even be utilized as a pivot stop for the L-profiled. When the roller 66 has been guided to the end of the rail 84, the roller, during its further advancing, will abut against the thus swung-out end portion 90 of the flange portion 88 of the L-member, and since the pivot connection is located near the outer edge of the bottom flange of the substantially C-shaped fail 84, the abutment will cause the L-profiled member 86, by its engagement with the roller 66, to swing back into its initial position by the passage of the roller through the discussed area. 
     Thereafter, the roller 66 will be pulled first somewhat downwardly by its cooperation with the top flange of the inclined rail 84, whereby the rollers 72 on the arm 64 will be moved downwardly in the track portions 76 such that the roller 66 will thereafter be blocked against leaving its engagement with the rail 84, and thereafter, the roller is drawn further downwardly during its following passage along the rail 84. The system is designed such that the rail 84 at its lower end stops just where it has operated to pull the roller 66 down to a level (FIG. 5) in which the rollers 72 get the opportunity to retreat into the lower track ends 78 by the action of the spring 83, whereby the roller 66 will be pulled away from its engagement with the rail 84. 
     In the initial phase it will be the upper flange of the rail 84 that will be active for the pulling down of the arm 64, but in the following it will rather be the lower flange that is effective for a guiding down of the roller 66, namely upon the tilting having reached the point where the point of gravity of the tilted mass has been displaced considerably to the outside of the tilting axis 34. It will be appreciated that the tilting movement is thus under full control right from the beginning to the end thereof, this being a remarkable advantage. 
     It is an important condition, of course, that the actuation rollers 66 can freely pass the discussed means for guiding the rollers downwardly when passing the non-actuated unloading stations, but this is easily achievable by the rollers 66 in their normal positions (FIG. 4) not even projecting out to the area in which the rail 84 is located. 
     For the required actuation pivoting of the L-shaped rail member 86 any suitable mechanism can be used, e.g. a magnet 92 as shown in FIG. 6. It is sufficient that magnet 92, by a brief actuation impulse, swings to the L-shaped member 86 outwardly. Thereafter the magnet need not effect any holding action on the swung out L-shaped rail member 86; this member will be self supporting during the outward movement of the roller 66, and as mentioned it will swing back by a purely mechanical influence from the roller 66 itself, i.e. the actuation member used has no other effect than bringing the light L-shaped rail member 86 into its actuated position, which can be done very fast and with a minimum of energy consumption. For extra security and ease of actuation, however, it is preferred to let the L-shaped rail member 86 be spring biased for swinging into an actuated position in response to a locking pawl being released by the magnet 92: by the following swinging back of the L-shaped rail member 86 this 86 will get into a snap lock engagement with the locking pawl. 
     In the left hand side of FIG. 7 is illustrated an actuated run-through of the roller 66, while in the right hand side a non-actuated run-through is illustrated. 
     As mentioned, the actuated units will be locked in their tilted out positions by the action of the spring 83, and of course they should be brought right again before they are returned to the loading station L. However, such a righting will be easy to effect, viz. by means of rigid guiding or cam means mounted in front of the loading station so as to be able to pull out the rollers 66 from their respective lower positions (FIG. 5) and to thereafter guide the rollers upwardly into their normal positions (FIG. 4), in which they are self locking by the action of the spring 83. 
     It should be mentioned that the use of the loose tray carts or separate cart trains with a number of trays will involve the possibility of providing sorter systems, in which, with the use of rail switches, it is possible to operate on more rail sections coupled in parallel, whereby according to the requirements branchings can be provided both in the horizontal and the vertical plane. 
     It is a special possibility that on each cart chassis or on just some of them, for example, two or more trays 6 be arranged in a series. The carts should carry suitable identification means that are detectable by their passage of the unloading stations.