METHOD FOR DRIVER SUPPORT ON AN INSTALLATION CONVEYOR

Description

[0001] The invention relates to a method for driver assistance in a forklift truck. In particular, the invention relates to a method for driver assistance in monitoring the load capacity limits of a forklift truck, wherein the forklift truck has a lifting mast with a load-handling device, in particular a load fork, which is guided vertically on the lifting mast, and wherein an optically readable lifting height indicator is attached to the lifting mast, which is formed from a scale and a marking that interacts with this scale, wherein the scale and the marking are arranged on parts of the lifting mast and / or load-handling device that move relative to each other during a lifting movement, and the forklift truck has a control device with a display device and detection means for a load weight.

[0002] In the prior art, industrial trucks, in particular counterbalance forklifts, reach trucks, and other industrial trucks with lifting devices, are known in which a height-adjustable load-handling attachment, in particular a load fork, can be moved vertically along a lifting mast. Lifting masts are known in designs with a fixed mast and one or more extendable masts. Furthermore, so-called free-lift masts are known as variants, in which the load-handling attachment is first moved to its highest possible position, and only then are the extendable mast(s) raised, so that loads can be lifted to approximately the height of the fixed mast without increasing the overall height of the industrial truck.

[0003] To inform the driver or operator of such a forklift truck about the lifting height, devices are known that measure the lifting height and display it on a display device, for example, a screen at the driver's workstation. These can be ultrasonic or laser measuring devices, but also a mechanical measuring device such as one using a cable pull whose unwound length is measured.

[0004] A disadvantage of this state of the art is that it requires a relatively high level of effort and the risk of damage in harsh everyday use is not insignificant.

[0005] Solutions for displaying the lifting height are therefore known in which a scale is marked on the mast or mast sections, and when the respective inner extension mast is extended or when the load-handling device is raised, a mark opposite the scale indicates the lifting height. Such a prior art is disclosed, for example, in EP 0 949 191 B1.

[0006] DE 10 2011 012 416 A1 discloses a display device for showing the stability reserve of an industrial truck.

[0007] DE 102 07 017 A1 discloses a device for measuring the lifting height of a load-carrying device of an industrial truck.

[0008] EP 2 172 413 A1 discloses a method for indicating permissible loads of an industrial truck.

[0009] The load-bearing capacity, and in particular the maximum load capacity, of a forklift truck is specified using a load capacity diagram, which primarily relates a load weight to a maximum permissible lifting height. As a rule, for reasons of stability, it is not permissible to use the maximum lifting height with the maximum load weight. Thus, the load capacity diagram indicates for each load weight the maximum lifting height, or whether lifting to the maximum height is permitted.

[0010] To assist an operator or driver in estimating the load weight, it is known to provide a device for measuring the load weight. A known load weight measuring device, in the case of hydraulic lifting devices, particularly hydraulic cylinders, measures the pressure in the hydraulic system and, taking into account the weight of the lifted mast elements and components, determines the load weight from this pressure. The determined load weight can then be displayed on a display device, such as a screen, at the operator's workstation.

[0011] A disadvantage of the previously described state of the art is that a relatively high effort is required for an exact and electronic measurement of the height and / or a driver has to read the lifting height corresponding to a load weight in a load capacity diagram.

[0012] The present invention is therefore based on the objective of providing a method for driver support in a forklift truck that avoids the aforementioned disadvantages and with which compliance with the permissible lifting heights to load weights can be monitored in the simplest possible way.

[0013] This problem is solved by a method having the features of independent claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0014] The object of the invention is achieved in a method for assisting driving in monitoring the load limits of an industrial truck, wherein the industrial truck has a lifting mast with a load handling device, in particular a load fork, which is guided vertically on the lifting mast, and wherein an optically readable lifting height indicator is attached to the lifting mast, which is formed from a scale and a marking that interacts with this scale, wherein the scale and the marking are arranged on parts of the lifting mast and / or load handling device that move relative to each other during a lifting movement, the industrial truck has a control device with a display device and detection means for a load weight, the control device determines a load weight from a signal from the detection means, determines a maximum lifting height for this load weight and displays it on the display device.

[0015] This approach offers the advantage of increased safety and ultimately also the performance of the forklift, as the operating limits are easily discernible for the driver or operator. As soon as the control unit receives a signal from the load weight sensors indicating that a load has been picked up, the load weight is determined, and from this, the maximum permissible lifting height for that load weight is calculated. This can be done, for example, using a stored characteristic map or a table. The maximum permissible height for the load weight is displayed on the display. Additionally, the load weight can be displayed, possibly only for a short period. From the position of the marker relative to the scale on the mast, the operator or driver can see the achieved lifting height and monitor that the maximum permissible lifting height is not exceeded.The described method is easy and inexpensive to implement. In particular, no complex and expensive device for electronically measuring the lifting height is required.

[0016] In a further development of the method, the lifting mast has a hydraulic lifting device and the measuring means for the load weight record the hydraulic pressure of the hydraulic lifting device.

[0017] This method of measuring load weight is very robust and insensitive to contamination and damage. By measuring the hydraulic pressure, which can be achieved not only with a pressure sensor but also, for example, through other methods such as measuring the starting currents of pump motors, no sensor is required on the load-handling device, and no signal cable needs to be routed through the lifting mast.

[0018] The detection devices can consist of a pressure sensor.

[0019] In a further embodiment of the method, the lifting mast has at least one extension mast, the scale is located on the extension mast and the marking is located on a guide part of the lifting mast that is external to the extension mast, in particular a support mast.

[0020] In a lifting mast consisting of a fixed mast and at least one inner extension mast, the scale can be located on the extension mast, and the marker, for example, a triangle as a stylized arrowhead, can be located at the top of the fixed mast. When the inner extension mast is raised, the scale moves along the marker and indicates the respective lifting height. For a lifting mast with multiple extension masts, a second, further inward extension mast can, according to the same principle, have a scale that interacts with a marker on the extension mast that guides it, or on the central section in the case of a triplex mast.

[0021] The marker can be an arrowhead.

[0022] The scale advantageously features several colors.

[0023] The scale can display a sequence of colors from green to yellow to red as the lifting height increases.

[0024] Often, the full lifting height can be utilized up to a certain load weight. Conversely, even at maximum load weight, a specific lifting range can always be used. Therefore, if this range is displayed in green, for example, it immediately becomes clear to the driver or operator that there is no danger and no additional attention is required. In a transition zone, this can be clarified by a change in color, and increased attention can be drawn, particularly in the area of ​​maximum lifting height, for example, by a red zone.

[0025] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiment shown in the schematic figures. Here, Fig. 1 schematically shows a forklift truck in which the method according to the invention is applied, Fig. 2 shows a section of a triplex mast of the forklift truck. Fig. 1 , Fig. 3 the upper section of the fully raised triplex mast of the Fig. 2 , Fig. 4 a first screen representation of the display device and, Fig. 5 a second screen representation of the display device.

[0026] The Fig. 1 Figure 1 schematically shows a forklift truck 1 in which the method according to the invention is applied. The forklift truck 1 is a high-lift pallet truck 2, which is controlled via a tiller 3 and is designed as a pedestrian-operated vehicle, in which the operator walks alongside the vehicle. A lifting mast 4 is designed as a triplex mast 5 and enables the lifting of a load-handling device (not shown here). As indicated by the first, shorter arrow 6, in an initial lifting range, a control device determines the load weight after a load has been picked up. The maximum permissible height for the load is displayed on a display device. In a further lifting range, indicated by the second arrow 7, the operator can visually monitor compliance with the permissible height on the lifting mast 4.

[0027] The Fig. 2 shows a section of the triplex mast 5 of the industrial truck 2 of the Fig. 1 with a fixed mast 8, a first extendable mast 9, and a second extendable mast 10, which is guided on the first extendable mast 9. A load-handling device 11 is guided on the second extendable mast 10. A piston rod 12 of a lifting cylinder with pulleys 13 is part of a hydraulic lifting device. A marker 14 in the form of a triangle 15, resembling a stylized arrowhead, is arranged on the fixed mast 8. A scale 16 on the first extendable mast 9 indicates a lifting height relative to the marker 14 when the first extendable mast 9 is raised.

[0028] In the lifting range effected by the lifting cylinder with the piston rod 12, for example a free lift, with which the load handling device 11 is first raised to the highest position on the second extension mast 10 before the extension masts 9, 10 are raised, a further marking 17 on the piston rod 12 opposite a second scale 18 on the second extension mast 10 also indicates a lifting height.

[0029] The Fig. 3 shows the upper section of the fully raised triplex mast 5 of the Fig. 2 with the second extension mast 9 fully raised and the piston rods 12 fully extended from a hydraulic cylinder 19.

[0030] The Fig. 4 Figure 1 shows a first screen display of the display device 20, in which the load weight detected and determined by the control device is displayed on a stylized load fork 21; in this example, 1250 kg. A maximum lifting height is also displayed; in this example, 0.4 m. This is a forklift truck that can handle increased loads within a small lifting range of, for example, 500 mm, for which greater lifting heights are not permissible.

[0031] The Fig. 5A second screen display of the display device 20 is shown. This displays a warning that the load weight is too high for 0.6 m. This can occur, for example, if an attempt is made to lift an increased load from a shelf compartment above 500 mm.

Claims

1. Method for supporting a driver when monitoring the load-carrying limits in an industrial truck (1), wherein the industrial truck (1) has a mast (4) having a load-receiving means (11), in particular a load fork, which is guided so as to be height-adjustable on the mast (4), an optically readable lifting height display which is formed by a graduation (16, 18) and a marking (14, 17) interacting with this graduation (16, 18) being attached to the mast (4), wherein the graduation (16, 18) and the marking (14, 17) are disposed on parts of the mast (4) and / or of the load-receiving means that move relative to one another during a lifting movement, characterized in that the industrial truck has a control device having a display device (20) and detection means for a load weight, wherein the control device determines from a signal of the detection means a load weight, and determines and displays on the display device (20) a maximum lifting height associated with this load weight.

2. Method according to Claim 1, characterized in that the mast (4) has a hydraulic lifting device, and the detection means for the load weight detect the hydraulic pressure of the hydraulic lifting device.

3. Method according to Claim 2, characterized in that the detection means are composed of a pressure sensor.

4. Method according to one of Claims 1 to 3, characterized in that the mast (4) has at least one extendible mast (9, 10), the graduation (16) being disposed on the extendible mast (9) and the marking (14) being disposed on a guiding part of the mast that in terms of the extendible mast is an outer guiding part, in particular a vertical mast (8).

5. Method according to one of Claims 1 to 4, characterized in that the marking (14) is the tip of an arrow (15).

6. Method according to one of Claims 1 to 5, characterized in that the graduation (16, 18) has a plurality of colours.

7. Method according to Claim 6, characterized in that the graduation (16, 18), as the lifting height increases, has a sequence of colours from green via yellow to red.