Driverless transport vehicle for individual goods

Abstract

Driverless transport vehicle for individual goods, comprising a loading area (3) for at least one individual item, which is arranged on a chassis (4), wherein the loading area (3) has a holding element (6) on at least one side, and comprising a vehicle control system which is configured to always align the vehicle during transport of the goods in such a way that the acceleration when starting off, cornering and decelerating presses the at least one individual item against the holding element (6), characterized in that the surface (3a) of the loading area (3) has two regions with different friction values, wherein the second region (X) only borders on the holding element (6), the first region (Y) is arranged on the side of the loading area facing away from the holding element (6), and the first region (Y) has a reduced friction value compared to the second region (X).

Description

The invention relates to a rodless transport vehicle according to claim 1.Transport vehicles, in particular autonomous or keyless transport vehicles, which serve as carriers of goods are known. For example, US 2013 / 0 054 005 A1 discloses so-called autonomous "bots" which move mobile racks.Corresponding transport vehicles for individual goods or cargo are also known, for example, from CN 2 08 018 986 U, in which the goods rest on a loading surface on the top side of the transport vehicle.DE 10 2019 122 055 A1 likewise describes a small autonomous transport vehicle for individual goods, which stabilizes a goods item accommodated on a load surface on the vehicle during the movement in that a raised wall is present on one side of the load surface. The vehicle is always rotated during the transport of the goods such that the acceleration during starting, when cornering and when decelerating presses the goods against this elevated wall. Thus, dropping is prevented.For delivering the individual goods, the movement vector of the vehicle is changed immediately before or upon arrival at an unloading station and the vehicle is oriented by the vehicle controller and / or by at least one guide device arranged in the region of the unloading station before arrival at the unloading station such that the movement path of the goods moving away from the loading surface due to the change in the speed vector ends in a receiving region of the unloading station. In other words, the article continues to move with the original vector before the change and thus slips off the loading surface of the transport vehicle by the force of gravity or inertia of the movement.It is additionally described that the coefficient of friction of the entire loading surface can be actively changed by rolling. These are initially located below the load surface and can be raised relative to the load surface for unloading, so that they come into direct contact with the goods through openings in the load surface. This simplifies the dispensing of goods by means of inertia, since the goods can be dispensed via the roller surface with less friction. During transport, the rollers are lowered and the goods are securely held on the load surface by the comparatively higher friction.The raising and lowering of the rollers, however, requires a corresponding mechanism which must be activated and actuated. This requires energy to be (additionally) provided, for example with a battery. On the other hand, such a mechanism and power sources increase the weight of the vehicle and thus degrade the energy balance and decrease the payload, respectively. By raising and lowering, the mechanism requires additional vertical installation space. As a result, the load is transported at a greater height and the load transport is thus more unstable. It must also be ensured that the mechanism does not accidentally reduce friction during transportation, as this would involve the risk of loss of load. Small accelerations-triggered, for example, by unevenness of the floor-could lead to the goods slipping. Thus, corresponding monitoring and securing are necessary.These mechanisms make the vehicle more complicated and complex and thus increase the probability of failure, whereby the reliability is reduced.In contrast, the object of the present invention is to provide a corresponding improved transport vehicle which does not have the above disadvantages.This object is achieved by the transport vehicle as set forth in claim 1. Advantageous embodiments are evident from the dependent claims and the description.According to the present invention, it has been recognized that when the surface of the load surface has two regions having different friction values, it becomes possible to improve the unloading operation.The loading surface thus comprises two areas, one with high friction on the holding element and one area with low friction on the delivery side.During the receiving, the item to be loaded or the item is stripped (e.g. by the holding element for receiving on the loading surface) and lies on the loading surface both in the first and in the second region.During transport, the vehicle is always rotated, as described in the above-mentioned patent applications, in such a way that the goods item are pressed against a corresponding holding element (e.g. raised wall) by the accelerations applied. Slipping due to small accelerations, for example in the case of small unevenness in the ground, is prevented by the high friction in the second region.For the load delivery by means of inertia, a delivery of the goods over the delivery edge is provided. For this purpose, the vehicle, for example, starts the transfer station with the delivery edge leading, decelerates greatly shortly before the load delivery is reached, so that the goods or cargo can slide over the load surface onto the load delivery station with sufficiently low friction.In other words, it has been recognized that this type of load output is improved by the two-part configuration of the load surface with regions of different friction.This will be explained by the example shown below:The homogeneous load 20 of mass m having a square base and a height of one quarter of the edge surface is to be discharged with a delay equal to the acceleration of gravity. For simplification, it is assumed that the cargo only rests on the load surface 23 at its edges 21 and 22, symbolized in the image by the arrows: In the first case according to the prior art, the entire loading surface is provided with a surface with a certain friction. During deceleration, a (adhesion) frictional force must then be overcome, which can be calculated as the product of the coefficient of friction, the mass of the cargo and the acceleration due to gravity.In the second present case according to the invention, the coefficient of friction on the side facing the load delivery station is lowered, for example, to one tenth of the coefficient of friction assumed previously. Then, the frictional force that must be overcome to discharge the load drops to about 1 / 3 of the frictional force of the first case. With this reduction, charge delivery is substantially simplified.By means of the invention, cargo items can therefore be safely discharged by inertia without substantially increasing the mass and the overall height of the transport vehicles. At the same time, slipping of the load during transport is prevented. No sensors or actuators are necessary, so that the reliability is given and the structure of the vehicle is simplified.According to the invention, the second region adjoins only the holding element and the first region is correspondingly arranged on the side of the load surface facing away from the holding element.The first region is therefore that region which simplifies the above-described discharge function during discharge and lies closer to the "discharge edge".Accordingly, the first region has a reduced coefficient of friction compared to the second region.In particular, the coefficient of friction of the first region is permanently reduced. In other words, it is not actively changed as in the prior art, but is statically lower than that of the second region.Low friction of the first region can be achieved, for example, by the use of rollers, balls, special materials with low friction or smooth surface. It is also conceivable to generate low friction by using a passive belt conveyor in which a belt is wound around two passive rollers.It is also possible for the coefficient of friction of the first region to be reduced only in a preferred direction. Lateral movements could thus be prevented for this purpose. The preferred direction is expediently the discharge direction; thus extends away from the holding element in the direction of the side of the load surface facing away from the holding element. Thus, rollers fixedly installed in the first region with an axis oriented transversely to the preferred direction could be used. It is also conceivable to equip the surface of the second region with a scale-like coating which reduces the friction only in one direction and "locks" in other directions.A coefficient of friction of the surface in the first range of less than or equal to 5%, preferably less than or equal to 3%, and particularly preferably less than or equal to 1% has proven to be particularly suitable. These values apply in particular when using rollers fixedly installed in the first region.In addition, it can be provided that the discharge edge forms a third region with an even reduced coefficient of friction.It is also conceivable for the first region and / or the third region to be set slightly lower (1-3 mm) than the second region, so that dispensing is facilitated once again.It is understood that the individual product, a product itself or a container or tray, etc., can be filled with product(s).In addition, goods can be designed as a stack of two goods units, in particular if they are each present in containers which engage one another and thus prevent slipping with respect to one another.Depending on the size of the load surface or the article(s), two or more articles can also be transported or picked up on the load surface simultaneously.The holding element can be formed as a simple raised wall on a side of the load surface (facing away from the unloading direction). In addition, the holding element can also comprise lateral regions of the load surface adjacent to the side facing away, so that transverse accelerations of the goods are also well absorbed.Further details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing, in which FIG. 1 shows a schematic view of a transport vehicle according to the invention during an unloading process; FIG. 2 shows a top view of a first variant of an embodiment of the loading surface of the transport vehicle from FIG. 1 ; FIG. 3 shows a top view of a second variant of an embodiment of the loading surface of the transport vehicle from FIG. 1 ; and FIG. 4 shows a plan view of a further variant of an embodiment of the loading surface of the transport vehicle from FIG. 1 show.In the figures, a sensorless transport vehicle for individual articles denoted as a whole by 1 is shown, having a loading surface 3 for at least one individual article 2 which is arranged on a driven chassis 4. The transport vehicle in the present case has a substantially cylindrical shape. It is understood that deviations therefrom are also possible.The load surface 3 is designed as a flat surface on the top side and has a holding element 6 in the form of a raised wall at least on one side.The transport vehicle also comprises a vehicle controller 5, which is configured to always align the vehicle during transport of the item such that the acceleration during starting, cornering and deceleration presses the at least one individual item against the holding element 6. For this purpose, the vehicle controller 5 comprises, in addition to the drive controller, also a corresponding sensor system.The holding element 6 is designed as a partially circular wall in the present case and thus also offers certain restraining forces against the goods slipping laterally.The chassis 4 comprises correspondingly indicated individually driven wheels etc. which allow omnidirectional movement of the transport vehicle 1.As shown in FIG. 1, the transport vehicle 1 moves at high speed in the direction of an unloading station 7, where the goods 2 are discharged.For this purpose, the transport vehicle 1 decelerates or brakes sharply shortly before reaching the unloading station 7, so that the goods 2 on the load surface 3 start to slide over the load surface 3 due to inertia in the direction of the unloading station 7 (see arrow 8 - unloading direction) and ultimately land on or in the unloading station 7.According to the invention, the surface of the load surface 3 is divided into several areas. These differ in the coefficient of friction or the friction experienced by the article there.For this purpose, various exemplary embodiments or variants are explained in FIGS. 2 to 4.In all variants, the loading surface 3 has a first region Y with a first coefficient of friction and a second region X with a second coefficient of friction, wherein the first coefficient of friction is reduced or reduced compared to the second coefficient of friction, so that the product experiences less friction in this region or slides faster and better during deceleration for dispensing.The second region X adjoins the holding element 6 and the first region Y is arranged on the side of the loading surface 3 facing away from the holding element 6, i.e. lies in the unloading direction 8.The coefficients of friction are permanently reduced in the present case, i.e. they do not change actively as in the prior art, where an active mechanism lifts rollers, etc.In the embodiment of FIG. 2, a smooth teflon coating is applied in the first region X and a smooth stainless steel surface in the third region Z for setting the reduced coefficient of friction or reduction of friction.In the embodiment of FIG. 3, the reduced friction is achieved by means of a plurality of rollers 9 which are fixedly installed in the surface of the first region Y and the orientation or axis 10 of which is configured such that they rotate only in the preferred direction of the unloading direction 8.In the embodiment of FIG. 3, the reduced friction is achieved by means of a plurality of flakes 11 made of teflon, which are arranged in the region Y, which is also located 2 mm lower from the level in comparison with the second region X on the holding element 6.

Claims

A rodless transport vehicle for individual goods, comprising a loading surface (3) for at least one individual goods, which is arranged on a chassis (4), wherein the loading surface (3) comprises a holding element (6) at least on one side, and comprising a vehicle controller, which is configured to always align the vehicle during transport of the goods such that the acceleration during starting, cornering and deceleration presses the at least one individual goods against the holding element (6), characterized in that the surface (3a) of the loading surface (3) comprises two regions with different coefficients of friction, wherein the second region (X) only adjoins the holding element (6), the first region (Y) is arranged on the side of the load surface facing away from the holding element (6), and the first region (Y) has a coefficient of friction which is reduced in comparison with the second region (X).Transport vehicle according to Claim 1, characterized in that the coefficient of friction of the first region (Y) is permanently reduced.Transport vehicle according to claim 2, characterised in that the coefficient of friction of the first region is reduced by using rollers (9), balls or special materials (11) with low friction present in the first region (Y).Transport vehicle according to one of Claims 1 to 3, characterized in that the coefficient of friction of the first region is reduced only in a preferred direction (8).Transport vehicle according to claim 4, characterised in that the preferred direction extends away from the holding element (6) in the direction of the side of the loading surface (3) facing away from the holding element (6).Transport vehicle according to one of the preceding claims, characterized in that the height of the first region (Y) is slightly lowered with respect to the height of the second region (X).Transport vehicle according to one of the preceding claims, characterized in that it is controlled by the correspondingly set-up vehicle controller in such a way that the vector of the speed of the vehicle (1) changes immediately before or upon arrival at an unloading station (7) and the transport vehicle (1) is aligned by the vehicle controller (5) and / or by at least one guide device arranged in the region of the unloading station (7) before arrival at the unloading station (7) in such a way that the movement path of the individual product (2) moving away from the loading surface (3) on account of the change in the speed vector ends in a receiving region (14) of the unloading station (7).

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