SELF-LEVELLING DEVICE

Abstract: Self-levelling lifting device for a platform (1) loaded with articles, such as container packed foodstuffs, comprising a translation device (3) for the upward and downward movement of the platform (1), said levelling device comprising two inextensible belt-like elements (8) with a middle portion lying under the platform (1) and with an upwardly and downwardly directed section, said middle portions crossing (S) each other.

Description: Sel -levelling device. BACKGROUND OF THE INVENTION The invention relates to a device for upwardly and down¬ wardly guiding a platform between two end positions using a translation device which is fixed to the platform, whereby the translation device consists of a positively driven element located next to the platform for raising and lowering the platform, an arrangement being provided for maintaining the horizontal position of the platform consisting of two inextensible cable-like elements, each of which is guided by two guiding devices located under¬ neath the platform, one device being provided on that side of the platform where the translation device is located whilst the other guiding device is present on the opposite side, in such a way that each cable-like element proceeds upwardly from a level close to the lowest end position and is guided upwardly over the first-mentioned guiding device, then passes underneath the second guiding device and from this point proceeds upwardly to a level close to the top extreme position of the platform. Various embodiments of such a device are known, serving mainly to keep a wide variety of identical utensils, such as dinner plates, within manual reach. According to French Patent 833 872 this device is used for the vertical up and down movement of a lift bridge for cars. The arrangement for maintaining the horizontal position of the lift-bridge consists αccording to Fig. 7, of α single translation device in combination with two parallel cable-like elements and a third cable-like element. The embodiment shown in Fig. 8 of said French Patent also utilizes three elements * / Accordingto Figs. 1-6 a further embodiment is known com¬ prising two translation devices in combination with two parallel cable-like elements. When only a singe translation device is employed for guiding the platform, the problem arises that in the event of unbalanced loading the platform has the tendency to adopt a slanting position with the result that jamming can occur whilst at the same time the objects present on the plat¬ form can slip and hence increase the tendency of the plat¬ form to adopt a sloping position. This has tijen to be levelled. SUMMARY OF THE INVENTION The present invention aims at providing a simple design solution for the said problem, to which end the device in accordance with the invention differs in that it pro¬ vides facilities for maintaining the horizontal state of the platform, consisting of two belt-like elements each of which are employed, the* portions lying underneath the platform crossing each other while - where viewed from the .top - the translation element and the upwardly-directed sections of both belt-like elements form the corners of a triangle, within which the centre of gravity of the plat¬ form is located. By these means the platform is only supported at one position along its periphery by the translation device, whilst on the opposite side the plat- form is supported by two upwardly directed sections of the inextensible elements. It should be noted that the expression "belt-likeelement" is understood to signify a flat member occupying little space, provided that this is inextensible. The indicated triangular configuration guarantees the stability of the platform, even during the positive upward and downward movement of the platform. Since the said arrangement con¬ sists of only two inextensible elements, the translation device which is effective against the underside of the platform can restrict itself to exercising a vertical force and no bending or twisting couples will be exerted upon said device. The invention relates particularly to a device, the translation element of which consists of a threaded rod cooperating with a nut, such as employed in the packaging unit according to European Patent 0.001.316. Herein the respective platform has a rectangular shape. In accordance with the invention, the said two belt-like elements are located in two mutually perpendicular planes, whereby the element in one plane interacts with the translation device positioned near a corner of the platform, whilst the elements cross each other at a point which is located closer to the two sections of both elements facing downwardly underneath the platform, than to the sections facing upward¬ ly above the platform. In this embodiment also a single translation device will suffice and this engages eccentrically with the platform, this eccentric loading being compensated for by the / *-^ j RE_ < ξ αscending sections of the inextensible elements which are located as far as possible away from the translation device. The triangular configuration thus obtained favourably influences the stability of the platform. In the application of the invention to a device in which the translation device is not positively driven, the translation device is formed by at least one elastic rubber band on which the platform rests, the said band proceeding upwardly on either side of this platform and then proceeding downwardly via a roller to the level of the lowest extreme position. The rubber band has a considerable length and can thus serve to carry the platform from the topmost level (in the unloaded state) down to the lowest level (in the fully loaded state). BRIEF SURVEY OF THE DRAWINGS: Figure 1 is a perspective view of the essential components of the device and the arrangement employed therewith. Figures 2 and 3 are sections through planes II and III respectively, in Fig. 1. Figures 4-ό are three very schematical further embodiments of the arrangement in accordance with the invention. DESCRIPTION OF PREFERRED EMBODIMENTS; Figure 1 is a rectangular platform or loading table 1 which can be designed as a flat plate or any desired flat rigid and possible hollow construction. This loading table 1 will usually be present as a carrying platform in an enclosure 2, e.g. designed as a box-shaped packaging unit. -5- The platform 1 interacts with a translation device 3 which in the embodiment of figs. 1-3 is designed as a nut 4, inter¬ acting with a threaded rod 5, which at its top end carries a head 6. This head is designed to cooperate with a lever 1ό, shown in Fig. 4, for rotating the threaded rod and the resultant upward of downward movement of the nut 4. The drive for the threaded rod can naturally also be undertaken in a different way and, for example, be provided by a motor using an interposed reduction drive. The platform 1 rests on the translation device 3, for which purpose the nut 4 is provided with a lip 7 which is fastened to the ^ platform 1, or possibly is inserted into the latter. This lip 7 possesses a limited length, so that only that portion of the platform 1 adjacent to the translation device 2 is engaged. The invention provides an arrangement by means of which the portion of the platform 1 which is far removed from the translation device 3 is so carried and supported that during the upward and downward movement of the translation device 3, it maintains the horizontal position of the platform 1. This arrangement consists of two mutually crossing in- extensible belt-like elements 8, each of which passes around two guiding devices 9, 10 located underneath the platform 1. One guiding device 9 is located on the side of the platform 1 where the translation device 3 is located and the second guiding device 10 is on the opposite side. Each element 8 is now passed in such a way past the guiding devices 9, 10 that the element proceeds upwardly from a level near the underside of the enclosure 2 and is guided -6- upwαrdly and over the first-mentioned guiding device 9. Subsequently the element 8 extends underneath the platform 1, is thereupon passed underneath the second guide device 10 and then from this point proceeds upwardly to a level at the top face of the enclosure 2. As shown in the embodiments of Figs. 1-3 the inextensible belt-like element 8 is of restricted length and is at its ends fastened close to the bottom and °P side respectively, of the enclosure 2. However, it is also feasible to make the element 8 endless (8* in Fig. 2). In that case the fastening devices 11 can be dispensed with. By means of this arrangement the horizontal position of the platform 1 is maintained as the lip 7 provides a support for one side, and the upwardly facing, sections of the elements '8 with the guide device 10 for the opposite side of the platform. The embodiment of Figs. 1-3 is provided with two inexten¬ sible elements 8 which are located in two mutually perpen¬ dicular planes II and III. The element 8 in the first plane II interacts with the translation device 3 (Fig. 2). It should be noted that in each embodiment the plane II is located eccentrically i.e. that this plane does not pass through the centre of gravity G of the platform 1 (See Fig. 1). The element 8 from the second plane III is in this embodiment located in the centre area of the platform 1. The elements 8 cross each other at a location S which is located closer to the two portions directed downwardly underneath the platform of the two elements 8 than to the sections directed upwardly above the platform. This is shown most clearly in Fig. 1. Fig. 4 illustrates a practical embodiment wherein, in a αnner similar to the embodiment of Figs. 1-3, a single translation device 3 is used, whereupon a crank \6 is placed. In this case the belt-like elements 8 are accommo¬ dated within the enclosure 2. Due to the flat shape of three belts 8 very little additional space is required, whilst the products lying upon the platform cannot be damaged. The use of the two inextensible elements 8 as described hereinbefore ensures the maintenance of a hori¬ zontal position for the platform with the trays loaded with articles stacked upon said platform in the two mutually vertical directions of the platform during the raising and lowering of the platform. In the variant of Fig. 5 the platform 1 does not possess a . rectangular or polygonal shape, but is circular. The ele- ments 8 which interact with the single translation device 3 are lying in two mutually perpendicular planes of the platform 1. In order to be able to differentiate between the ascending and descending sections of the elements 8 in the top view of said Fig. 5, this diagram is annotated at the appropriate positions with a plus sign and a minus sign respectively. The triangular configuration of the support point is denoted with a dotted line. The embodiment of Fig. ό does not comprise a positively displaceable translation device, as used in the other variations. The translation device consists in this embo¬ diment of an elastic rubber band 12 on which the platform 1 rests. This band then proceeds upwardly on either side of the platform, via a roller 13, proceeding downwardly until being level with the lowest extreme position of the platform. As α result the latter embodiment appertains to the type of levelling devices, that is a device on which a large number of objects, e.g. packaged foodstuffs, can be placed. The strength of the band 12 is so matched to the weight of the objects that the topmost layer is always located at the same level, independent of the load on the platform. The considerable length of the band 12 renders a substantial displacement distance possible for the platform 1. The elements 8 are incorporated in a manner similar to that employed in Fig. 1. Instead of the rubber band 12 a spring 14 can be employed. In Fig. 6 too the triangular configuration is encountered. It should be noted that provisions can be made for in¬ creasing or reducing the tension of the rubber band 12. In this way the platform can be raised or precisely lowered to an extra extent if a requirement for this should exist (See arrow 15 in Fig. 6). Furthermore it should be noted that the triangular confi¬ guration according to the invention avoids the occureπce of a considerable bending couple in the nut 4, so that the lever arm of the load effective on the lip 7 can be taken extremely short, as opposed to the state of the art. the It is obvious that scope of the translation device 3 is not restricted to a threaded rod with nut, but can also exhibit different embodiments.

Claims: -9 - WHAT IS CLAIMED IS: 1. Device for the upward and downward guidance of a plat¬ form between two end positions using a translation device which is fixed to the platform, whereby the translation device consists of a positively driven element located next to the platform for raising and lowering the platform, an arrangement being provided for maintaining the horizontal position of the platform consisting of two inextensible cable-like elements, each of which is guided by two guiding devices located underneath the platform, one device being provided on that side of the platform where the translation device is located, whilst the other guiding device is present on the opposite side, in such a way that each cable¬ like element proceeds upwardly from a level close to the lowest end position and is guided upwardly over the first- mentioned guiding device, then passes underneath the second guiding device and from this point proceeds upwardly to a level close to the top extreme position of the platform, characterized in that two belt-like elements (8) are employed, the portions lying underneath the platfor , crossing each other, while - where viewed from the top - the translation device and the upwardly direction sections of both belt-like elements form the corners of a triangle, within which the centre of gravity of the platform is located. 2. Device according to claim 1, wherein the platform has a rectangular shape, characterized in that the two belt-like (8) elements are located in two mutually perpendicular planes and that the ele eπτ In one plane interacts with the translatio positioned near a corner of the platform deviceTfwhereby the elements cross each other at a point which is located closer to the two sections of both elements facing downwardly underneath the platform than to the upwardly directed sections located above the platform. 3. Device according to claim 1, in which the platform has a round shape, characterized in that the belt-like (8) elements are positioned in two mutually perpendicular diagonal planes of the platform, the downwardly facing sections of both elements lying at either side of the translation device. (3) 4. Device according to claim 1 in which the translation device is not positively driven, characterized in that the said translation device is formed by at least one elastic rubber bana "wi which the platform rests, said band proceeding ' upwardly on either side of said platform and proceeding downwardly via a roller 03) to the level of the lowest extreme position. -fTJRE-A

Inventors: BRINKERS G
Applicants: BRINKERS G
Application year: 1981
Main classification: B65G1
IPC codes: B65G1