Connecting element with integrated weighing unit for a lifting hook suspension

Description

[0001] The invention relates to a connecting element for a load hook suspension for connecting a load hook to a load receiving device for lifting equipment, having a recess for inserting and fastening the load hook.

[0002] Conventional load systems of a lifting device, particularly a crane, consist of a load-bearing unit, the so-called lower block, a load hook suspension, and a load hook. The load hook is connected to the lower block via the load hook suspension. The load hook suspension comprises a connecting element, a load hook nut, and a bearing between the connecting element and the load hook nut. The load hook is inserted into the connecting element and secured with the load hook nut. Different hook sizes can be connected to the same lower block using suitable connecting elements and can be interchanged as needed.

[0003] When operating lifting equipment, especially cranes, it is regularly necessary to weigh the load suspended from a hook. Various methods for doing this are known in the prior art.

[0004] Firstly, the lower blocks to which the lifting hook is connected are offered as special load units with integrated weighing technology. This means that to weigh a load suspended from the lifting hook, the entire lower block must be replaced during operation. This replacement or installation into existing systems, especially during operation, involves considerable time and physical effort.

[0005] Alternatively, separately attachable weighing systems are offered, which are suspended between the load hook and the load. However, this results in a significant change in the lifting height as well as the hook position where the load is suspended.

[0006] CN 202 382 832 U describes a suspended weighing device comprising a gravity sensor, an operating control circuit and a display device, wherein the suspended weighing device also includes a hook for suspending goods and a connecting piece for connecting the hook to a lifting device.

[0007] US 1,214,745 A describes, in combination with a hoist having a frame and a load-bearing element, means for weighing the load carried by the element, comprising an electrical measuring device, a control device connected to the device, a pressure-actuated device connected to the control device, a cylinder and a piston to the latter to which the load-bearing element is connected, and means for transmitting pressure from the cylinder to the pressure-actuated device. US 1,214,745 A forms the preamble of claim 1.

[0008] US 2015 / 323 377 A1 describes a detection device that detects the weight of the manipulated load and is integrated into a load-sensitive guide pin that is part of the axle bearing and can output a signal proportional to the effect caused by the load; a power source to provide drive energy for the load-sensitive guide pin; a sensor cable to transmit a drive voltage from the power source to the load-sensitive guide pin; and a calculation device that is in signal transmission connection with the load-sensitive guide pin to calculate the weight of the load corresponding to the signal from the load-sensitive guide pin.

[0009] US Patent 3,827,514 A describes a hook block device for weight measurement for cranes, which can be installed between the crane and the hook or other load-bearing device and can be used on existing cranes or as original equipment on cranes built later, comprising a hook block frame element that supports the ends of a substantially straight longitudinal bar which is elastically deformable in response to load forces applied to the bar.

[0010] The devices known from the prior art do not yet allow a weighing unit to be integrated into an existing system of load handling device and load hook without considerable effort and without loss of lifting height.

[0011] Based on this, the object of the invention is to provide a way to easily, quickly and without loss of lifting height extend a conventional load system of a lifting device by adding a weighing unit when required.

[0012] This problem is solved by the subject matter of claim 1. Preferred embodiments are found in the dependent claims.

[0013] According to the invention, a connecting element for a load hook suspension is provided for connecting a load hook to a load-bearing device of a lifting device, having a recess for inserting and fastening the load hook, wherein the connecting element comprises a weighing unit for weighing a load that can be suspended from the load hook and the connecting element comprises a crossbeam with geometric dimensions of a standard crossbeam according to DIN 15412.

[0014] When the term "load hook" is used here, it refers to a curved or bent component for suspending loads from lifting equipment. The load hook is preferably designed in accordance with DIN 15401 and / or DIN 15402. Lifting equipment is preferably understood to be a lifting device of a crane system.

[0015] When the term "recess" is used, it refers to a hole free of material into which a load hook can be inserted or passed.

[0016] A key aspect of the invention is that the connecting element linking the load hook to the load hook suspension of a load-handling device includes a weighing unit. The weighing unit does not need to be attached to the load hook, nor does it require a complex modification of the entire load system or replacement of the load-handling device for integration. A conventional connecting element is already integrated into the load system to connect the load hook to the load hook suspension. This conventional connecting element can be replaced with a connecting element according to the invention, which has an integrated weighing unit, in just a few simple steps. In this way, a conventional load system can be extended with a weighing unit as needed, without altering its external geometry. This ensures that the lifting height remains constant.

[0017] Furthermore, the connecting element includes a crossbeam, preferably a crossbeam with the geometric dimensions of a standard crossbeam according to DIN 15412. This makes the connecting element suitable for directly replacing conventional crossbeams, as the standardized geometric dimensions are identical to those of conventional connecting elements. Preferably, the load hook suspension also includes a standard load hook suspension according to DIN 15411 and / or the load-bearing device includes a lower block, preferably according to one of the standards DIN 15408, DIN 15409, or DIN 15410 and / or based on one of these standards. This ensures that the connecting element is suitable for conventional load systems consisting of standardized components and that the connecting element with integrated weighing unit can be easily replaced in existing load systems.

[0018] In principle, the weighing unit can employ different weighing technologies. According to a preferred embodiment of the invention, the weighing unit comprises at least one strain gauge. A strain gauge is a measuring device for detecting tensile and compressive deformations. Its electrical resistance changes even with slight deformations. In this way, deformations of the connecting element caused by attaching a load to the load hook coupled to the connecting element and the downward force of gravity are detected. The degree of deformation determines the change in electrical resistance. This allows conclusions to be drawn about the force of gravity or the weight attached. The measurement result is then preferably displayed via an external display unit, so that the weight of the load can be read directly at the connecting element and load hook.

[0019] According to a preferred embodiment of the invention, the connecting element has at least one cavity in which the at least one strain sensor is arranged. The strain sensor is therefore not, as is usually the case, glued onto the component under investigation. Rather, a cavity is created by drilling a hole in the connecting element, in which the strain sensor is arranged. This has the significant advantage that the geometric outer contour of the connecting element is not altered by gluing on a strain sensor.

[0020] According to a preferred embodiment of the invention, the weighing unit comprises at least two strain sensors, each arranged in a cavity. The arrangement of the strain sensors is selected such that they are point-symmetrical about the center of the recess. This has the advantage that at least two or more strain sensors are arranged point-symmetrically around the center of the recess, i.e., around the point where the weight force acts via the load hook, and that the radially propagating deformation of the connecting element can be measured optimally.

[0021] According to a preferred embodiment of the invention, the cavity is accessible from the outside and can be closed by means of a cap. In this way, the cavity simultaneously has a feed channel that allows the strain sensor to be inserted from the outside into the interior of the connecting element or into the interior of the cavity. Preferably, the strain sensor is accessible for servicing or repairs via a further service channel. Both the feed channel and the service channel can be closed during operation and protected from dirt, moisture, or contaminants.

[0022] According to a preferred embodiment of the invention, the weighing unit can be connected to a rechargeable power supply. Therefore, no precautions need to be taken regarding power cables when installing the connecting element. Preferably, the weighing unit can be connected to an external display unit, which includes the rechargeable power supply, for displaying the measurement results. The connecting element can then be connected to the battery-powered display unit. The rechargeable power supply or battery included in the display unit provides both the display unit and the weighing unit with the required current. This ensures that the connecting element does not need to be removed to recharge the rechargeable power supply. It is only necessary to disconnect the rechargeable power supply or the display unit, while the connecting element can remain installed.

[0023] According to a preferred embodiment of the invention, the weighing unit comprises an amplifier sensor coupled to each strain sensor. In this context, the amplifier sensor is understood to be a voltage amplifier, which enables the detection of minute voltages and thus changes in electrical resistance due to deformation. In this way, the weighing unit achieves increased measurement accuracy, thereby improving the overall quality of the weight measurement. Preferably, the amplifier sensor comprises a Wheatstone bridge circuit, which allows the relative change in resistance caused by deformation to be detected with high accuracy.

[0024] According to the invention, the use of a connecting element described above for connecting a load hook to a load-bearing device of a lifting device is further provided. The connecting element according to the invention with integrated weighing unit is specifically used to replace existing connecting elements without a weighing unit, so that existing systems consisting of a bottom block and load hook can also be supplemented with a weighing unit without significant effort or changes to the lifting height.

[0025] The invention will now be explained in more detail with reference to the drawings and a preferred embodiment.

[0026] The drawings show Fig. 1 schematically a load system according to the prior art, Fig. 2a schematically a connecting unit according to a preferred embodiment of the invention in a side view, Fig. 2b schematically a connecting unit according to a preferred embodiment of the invention in a top view.

[0027] Out of Fig. 1 A schematic representation of a crane's load system according to the state of the art is shown. The load system consists of a load-handling device 4 in the form of a lower block, a load hook suspension 3 attached to it, and a load hook 2 connected thereto. The load hook 2 is connected to the load hook suspension 3 by means of a conventional connecting element 1' in the form of a conventional spreader beam. A load can be suspended from the load hook 2.

[0028] If the suspended load needs to be weighed, either the entire lower block 4 can be replaced with one that has an integrated scale, or a scale can be attached to the load hook, and the load then hung from the scale, thus positioning the scale between the load hook and the load. The first option, the complete replacement of the lower block 4, has the disadvantage of being very complex and time-consuming. However, attaching an additional scale changes the lifting height. This leads to problems, as the originally intended or planned lifting height may no longer be achievable and may need to be recalculated.

[0029] To solve this problem or to avoid these disadvantages, the following is required in the Figures 2a and 2b A connecting element 1 with an integrated weighing unit 6 is shown. Figure 2a This shows a simplified schematic side view, while the Figure 2bA schematic top view is shown. The connecting element 1 is suitable for replacing the conventional connecting element 1' made of Figure 1 to replace one-to-one. This allows almost any existing load system to be extended in a particularly simple manner with the connecting element 1 according to the invention with integrated weighing unit 6.

[0030] The connecting element 1 is designed as a crossbeam. The crossbeam has the geometric dimensions of a standard crossbeam according to DIN 15412-1 and DIN 15412-2. To connect a load hook 2 to the connecting element 1, the connecting element 1 has a recess 5 into which the load hook 2 can be inserted. To the left and right of the recess 5, a cavity 8 is provided in the connecting element 1, in which a strain sensor 7 is arranged. The strain sensor 7 is mounted on the connecting element 1 within the cavity 8, for example by adhesive bonding, so that it can detect even the smallest deformations of the connecting element 1.

[0031] The strain sensors 7 are arranged symmetrically to the center 9 of the recess 5. When a load is attached to the load hook, this center 9 is the main point of application of the weight force, so that the deformation of the connecting element 1 propagates radially from the center 9. Due to the symmetrical arrangement of the strain sensors 7, this deformation can be detected uniformly. The strain sensors are accessible via both a feed channel 13 and a service channel 12, each of which can be closed by means of a cap 10. When installed, the service channels 12 are located on the front side, so they remain easily accessible.

[0032] The strain sensors 7 are coupled with amplifier sensors 11, which detect and amplify even the smallest voltages or changes in electrical resistance. In this way, even small deformations can be detected, so that the overall quality of the weighing unit can be improved, even with a connecting element 1 that has a relatively high stiffness.

[0033] In a conventional load system, such as in Figure 1As shown, the conventional standard traverse 1' can therefore be replaced by the standard traverse 1 according to the invention. A complete rebuild of the load system is no longer necessary. Only the load hook suspension needs to be modified. However, it is sufficient to remove the load hook for this purpose. The connecting element can then be replaced, so that a conventional load system can be extended with a weighing unit 6 without changing the external dimensions, in particular the overall height, or without the modifications involving increased effort. Reference symbol list

[0034] 1 Connecting element 1 'conventional connecting element' 2 Load hook 3 Load hook suspension 4 Load receiving device 5 Recess 6 Weighing unit 7 Strain sensor 8 Cavity 9 Center 10 Closure cap 11 Amplifier sensor 12 Service channel 13 Feed channel

Claims

1. Connecting element (1) for a load hook suspension (2) for connecting a load hook (2) to a load-receiving device (4) of a hoist, comprising a recess (5) for inserting and securing the load hook (2), wherein the connecting element (1) comprises a weighing unit (6) for weighing a load suspendable from the load hook (2), characterized in that the connecting element (1) comprises a traverse having the geometric dimensions of a standard traverse in accordance with DIN 15412.

2. Connecting element (1) according to claim 1 or 2, wherein the load hook suspension (3) comprises a standard load hook suspension in accordance with DIN 15411 and / or the load-receiving device (4) comprises a lower block, preferably in accordance with one of the standards DIN 15408, DIN 15409, or DIN 15410.

3. Connecting element (1) according to any of the preceding claims, wherein the weighing unit (6) comprises at least one strain sensor (7).

4. Connecting element (1) according to any of the preceding claims, wherein the connecting element (1) has at least one cavity (8) in which the at least one strain sensor (7) is arranged.

5. Connecting element (1) according to any of the preceding claims, wherein the weighing unit (6) comprises at least two strain sensors (7) each arranged in a respective cavity (8), and the strain sensors (7) are arranged point-symmetrically with respect to a centre (9) of the recess (5).

6. Connecting element (1) according to any of the preceding claims, wherein the cavity (8) is accessible from the outside and can be closed by means of a closure cap (10).

7. Connecting element (1) according to any of the preceding claims, wherein the weighing unit (6) is couplable to a rechargeable power supply.

8. Connecting element (1) according to any of the preceding claims, wherein the weighing unit (6) comprises, per strain sensor (7), an amplifier sensor (11) coupled to the strain sensor (7).

9. Use of a connecting element (1) according to any of the preceding claims for connecting a load hook (2) to a load-receiving device (4) of a hoist.