EP1602617B1 - LIfting apparatus with load measuring device and method to determine the load on a lifting apparatus - Google Patents

Abstract

Hoist (1), especially a cable or chain hoist, has at least a lifting gear (4) with at least a shaft (17) and a lifted load measuring arrangement. The load measuring arrangement has at least a sensor (9) for measuring the shaft deformation. The measured deformation is used as an input value for determining the lifted load. The invention also relates to a corresponding method for determining the load lifted by a hoist.

Description

The invention relates to a cable or chain hoist, with a lifting gear having at least one rotating shaft and with a Hublastmesseinrichtung, and a method for determining the lifting load of such a cable or chain hoist. Such a cable or process is off EP 0 841 298 known.

Hoists, such as rope or chain hoists have a specified life, which is dependent on the load and the load frequency distribution. In addition, an economic use of the hoists requires a high utilization. In order to determine the remaining service life each year, at least the operating hours and the load frequency distribution are therefore required as data.

Previously, the data needed to determine operating hours and load frequency distribution was manually recorded or estimated. However, this is expensive and inaccurate. Therefore, methods and devices have been developed to automatically count the operating hours, so-called hour meters. Corresponding methods and devices for monitoring the hoists are, for example, from DE 195 14 050 C2 . DE 196 17 105 C2 . DE 199 23 824 C2 . DE 199 56 265 A1 and DE 40 38 981 A1 known.

The monitoring data are automatically detected according to these methods and with these devices, possibly stored and displayed via displays, both the devices themselves and the displays are usually located in the hoist. For this purpose, it is known to either make a manual, optical reading of the display or to read out the data electronically by means of the provided interface and corresponding reading device.

In addition to the operating hours and the load frequency distributions are logged. For this, the lifting load must be determined.

However, the lifting load measurement also serves for safety, as the hoists are designed for a maximum lifting load, which must not be exceeded.

To avoid such overloading of the hoist, it is for example from the DE 34 42 868 A1 It is known to use limit switches which, after exceeding a predetermined spring force corresponding to the maximum load, switch off the hoist. Although the safety of the hoist is ensured during operation, no direct measurement of the actual hoisting load is possible.

For the actual measurement of the hoisting load, hoist load measuring devices with measuring elements such as strain gauges are therefore often used, which permit the actual hoisting load to be determined by means of the stretching of the measuring strips. These are usually combined with limit switches.

The usual devices, however, have a number of disadvantages. They are complicated and expensive. The strain gauges are usually not directly charged with the full lifting load, but this is mechanically reduced, z. B. via suitable levers. However, this requires an increase in size, in particular the height. Furthermore, only the force acting on the cable strand (or chain) is determined, but this is dependent on the reeving of the rope, so that it must be taken into account in the absolute determination of the lifting load. Also, no measurement without shearing is possible with these devices, as measured in the load line. Overall, therefore, a relatively complex evaluation of the signals and circumstances of the lifting load measurement must be carried out, which requires special electronics for evaluation in order to obtain the desired accuracy.

From the German utility model DE 203 00 942 U1 is a force transducer for measuring axle forces that act substantially transversely to an axis known. Such a force transducer can be used, for example, for measuring the forces acting on a cable pulley in order to prevent overloading of the cable pulley or the associated device. The load cell essentially has a longitudinally extending axle body on a first section designated as a force introduction zone for supporting the cable pulley. Two force measuring zones, which have a smaller diameter than the force introduction zone and the bearing zones adjoining the force measuring zones, adjoin each of these laterally on this first force introduction section. In the area of the storage zones, the axle is stored in appropriately trained cheeks. Within the Force measuring zones are provided transversely to the longitudinal extent of the axis aligned blind holes, are arranged in the strain gauges. These blind holes are each hermetically welded to the outside with a lid, so that the force measuring system is protected from environmental influences. For reasons of redundancy, in each case a blind bore with strain gauges are arranged in the force measuring zones opposite the cable pulley. The strain gauges can be used to measure the stresses, strains and shears of the material of the axle body in the area of the force measuring zone. The determined measurement signals can then provide information about the load on the pulley.

Furthermore, from the German patent DE 195 12 103 C2 a winch with an operational data acquisition known. In addition to a determination of speed and direction of rotation, the load on the cable winch is also measured via torque sensors. This winch is characterized essentially by a one-sided cup-shaped bearing support, which serves to receive a hydraulic motor and protrudes into a cable drum of the winch. The output shaft of the hydraulic motor acts via a gear on the cable drum of the winch. On the outer circumference of the fixed pot-shaped bearing support torque sensors are arranged in the form of strain gauges, via which the load of the winch in dependence on the deformation of the bearing support can be measured.

Furthermore, from the German patent DE 35 17 849 a torque sensor for a steering shaft or a transmission shaft of a motor vehicle known. The shaft is made of a ferromagnetic material or a non-ferromagnetic material coated with a film of ferromagnetic material. The torque sensor measures contactless torque applied to the shaft by sensing the magnetic permeability of the shaft. For this purpose, the torque sensor has an exciter winding unit with two excitation coils and a sensor winding unit with two sensor coils. Since the magnetic fluxes of the AC excitation coils pass through the shaft, the electrical signals generated in the sensor coils are dependent on the magnetic permeability of the shaft and thus on the torque applied to the shaft.

The US 4,766,977 discloses a device for determining the load of an elevator in the event that the elevator is unevenly loaded by the passengers. For this purpose, the torsion on a driven shaft of a cable drum is roofed, which is generated by the difference of the load of the elevator and the counterweight. To determine the torsion, a sensor operating on the magnetostrictive principle is provided on the shaft of the cable drum outside the drive gear.

The EP 08 412 98 A2 discloses a drive and control system for a hoist having a load handler in which a sensor including a force measuring device that measures an axial force on an axle within a reduction gear between the drive motor and the cable drum is used.

The object of the invention is therefore to provide a cable or chain hoist with Hublastmesseinrichtung and a method for determining the lifting load of rope or Kettenzugen in which the determination of the lifting load is as accurate and structurally simple. In addition, the structural design of the need for little or no space. Also, the lifting load measuring device should be reliable and inexpensive. Furthermore, a measurement without reeving or regardless of the reeving should be possible.

This object is achieved by the device reproduced in claim 1 and the method specified in claim 12.

The fact that the lifting load measuring device has at least one sensor for detecting the deformation caused by the lifting load of the shaft within the lifting gear and the detected deformation as a size for determining the lifting load, the lifting load can be determined very accurately. In these sensors, the shaft in the region opposite the sensor has first and second zones annularly disposed about the shaft axis, the second zone being positioned radially inward of the first zone, one of the zones having a permanent magnetization is longitudinally oriented in the direction of the shaft axis and the other zone provides a flow return path for the flow generated by the one zone, wherein the one zone is a magnetic field external of the region having a magnetic field component in a circumferential direction with respect to the shaft axis. The shaft of the transmission with the smallest diameter is used for the measurement. However, the transmission is particularly suitable because the waves there have a low material thickness, which increases the accuracy and speed of the measurement. In addition, no additional space is required for the measuring device by the measurement within the transmission and this is also protected. Further, with the invention Hublastmesseinrichtung a measurement directly with the hook on the rope ie without reeving possible because the measurement does not have to be located at the rope fixed point.

Furthermore, the invention allows a cost-effective production of the measuring device by eliminating the usual lever mechanism. In addition, the device is wear-free, since no contact of the components must take place with the moving components. Last but not least, the invention allows far-reaching insights into the statics and kinematics of the hoist by interpreting the measuring signal and enables extensive possibilities for monitoring the hoist.

As deformation, the torsion of the shaft is measured because this type of deformation occurs when the shaft is loaded with the lifting load as the main component.

The invention is based on the recognition that the shaft in the loaded state tends to deform, ie to twist or twist substantially. This angular deviation about the longitudinal or axial axis of the shaft can be determined and used as a measure of the applied force.

Ideally, the torque transmitted by the individual transmission shafts depends not only on the fixed geometric variables but also on the load hanging on the hook. However, this only applies to the static or the uniformly moving case. In contrast, in the accelerated movement, this must be taken into account when generating the torque on the cable drum. Likewise, the efficiencies based on friction (for example, rope stiffness and bearing friction) be taken into account in the different directions of rotation each with a corresponding sign.

The transmitted torque deforms the shaft according to its geometry and material properties. The deformation of the shaft and here in particular the torsion therefore corresponds to the torque which is transmitted.

The sensors determine the torque of the shaft, as these are known and available in large numbers. From the torque, the angular deviation occurring during the torsion can be calculated.

Conveniently, the sensors work magnetostrictively. For this purpose, the region of the shaft detected by the sensor is provided with a permanent magnetization of specific orientation. The alignment is advantageously carried out in the longitudinal direction of the shaft. This magnetic field is detected by the sensor designed as a magnetic field sensor. If the shaft is deformed or twisted under load, the magnetic field of the shaft changes as a result of its deformation and / or torsion. This effect is called magnetostriction. This change can be detected by the sensor and the lifting load thus determined via the detected deformation.

For this purpose, the shaft has at least one zone of permanent magnetization in the region opposite the sensor, the magnetization being oriented essentially longitudinally in the direction of the shaft axis and generating a magnetic field externally of the region having a magnetic field component in the circumferential direction with respect to the shaft axis is detected by the sensor. The permanent magnetization in the wave is created artificially.

Corresponding magnetized waves are z. B. from the EP 1 203 209 B1 known.

The above-described deformation of the shaft by the load to be lifted or lowered in turn causes a change due to magnetostrictive effects the magnetic properties or change in the shape of the magnetic field introduced into the shaft proportional to the deformation. This change in the magnetic properties or change in the shape of the magnetic field introduced into the shaft can be detected by means of a sensor which, for. B. has one or more coaxial and symmetrically mounted at the same distance special coils. The change in the magnetic properties is thus detected by the sensor or coil and converted into an electrical signal. An appropriate electronics prepares the signal and evaluates it. Instead of coils, the sensor may also comprise other suitable magnetic field-sensitive detectors, such as Hall effect semiconductor sensors, resistance sensors, Wiegand and pulse wires, or reed switches.

Advantageously, the sensors operate without contact so that signs of wear and disturbances due to contamination are minimized.

For optimum arrangement of the sensor on the shaft, the shaft is at least partially encompassing holder provided in one embodiment. Thus, z. B. two magnetic field sensitive detectors or coils are arranged on opposite sides of the shaft, so that two measurement signals are obtained, by means of which a more accurate measurement and possibly correction of the signals of environmental influences is possible.

Particularly accurate and reliable results are obtained if in each case 2 to 8, in particular 2, 4 or 8 magnetic field-sensitive detectors or coils per area are provided, which are arranged uniformly around the area. Then, in particular, a redundant connection of the sensor or the coils or evaluation of their signals can be made.

The holder may be fixed inside and / or on the transmission housing.

For processing the raw signals of the sensors, a signal processing device is provided. This can be a separate device. Preferably, however, it is the present in the control electronics of the hoist electronics such. B. microprocessor, etc. to use for the evaluation. As a result, additional parts are saved, which for reasons of maintenance, the simplification of the structure and construction and the reduction of the susceptibility to errors is desired.

Fig. 1

eine Einschienenlaufkatze mit Hubwerk und Lasthaken bei geöffnetem Getriebegehäuse;

Fig. 2

eine vergrößerte Ansicht des Getriebes aus Fig. 1 bei geöffnetem Gehäuse und

Fig. 3

eine Getriebezwischenwelle mit Drehmomentsensor aus Fig. 2.

Further features, advantages and details of the invention will become apparent from the following description of the drawing. Show it:

Fig. 1

a monorail trolley with hoist and load hook with the gearbox housing open;

Fig. 2

an enlarged view of the transmission Fig. 1 with the housing open and

Fig. 3

a transmission intermediate shaft with torque sensor Fig. 2 ,

FIG. 1 shows a designated as a whole with 10 monorail trolley with a frame 11 and an attached hoist 1. For moving on the lower flange of a rail, not shown, the monorail trolley 10 four rollers 12, which are each pairwise opposite and one of which via a motor 13 is driven.

The hoist 1 comprises a cable drum 6 which is driven by a motor 5 via a gear 4, wherein the gear 4 is arranged on one side of the cable drum 6 and on the opposite side a control electronics 8. The transmission 4 comprises at one of its intermediate transmission shafts a sensor 9 for lifting load measurement.

To the cable drum 6, a rope 7 is wound, which runs over a guide roller 14 and a lower block 2 with hooks 3. A hanging on the hook 3 load is raised or lowered by winding or unwinding of the rope 7 on the cable drum 6 by appropriate control of the motor 5.

Thus, depending on the respective static and kinematic conditions and the inserted shearing and the geometrical dimensions, the load hanging on the hook 3 generates a torque on the cable drum 6. This torque is transmitted to the motor 5 by the transmission 4 with the corresponding ratios of the intermediate shafts. If the motor 5 generates the same moment, the load is held. If the engine generates a higher torque, the load is lifted. If the motor generates a smaller torque, the load is reduced accordingly.

FIG. 2 shows the gear 4 of the hoist 1 in an enlarged view with the housing 15 open. The motor 5 drives via a corresponding motor pinion 16, an intermediate shaft 17 and a further following intermediate shaft 18, an output shaft 19 and above the cable drum 6 at. The respective shafts 17, 18 and 19 each have a bearing designated by the additional letter "A" and a gear designated by the additional letter "B". The gears are used to transmit the rotational movement of a shaft to each subsequent.

At the intermediate shaft 17, the sensor 9 is arranged. The sensor 9 comprises a circular attachment 20, followed by a developed arm 21, which merges into an attitude 22. About the attachment 20, the sensor 9 is attached to the housing cover, not shown.
The U-shaped support 22 partially surrounds the intermediate shaft 17, which in this region 17C has a longitudinal magnetization oriented longitudinally in the direction of the shaft axis. In the intermediate shaft 17 partially surrounding bracket 22 of the sensor 9 sensor coils are arranged as magnetic field sensitive detectors.

The intermediate shaft 17 with the sensor 9 goes out FIG. 3 in more detail. The holder 22 of the sensor 9 comprises coils 23. These coils 23 are the actual magnetic field detectors and each arranged in the holder 22, which surrounds the area of permanent magnetization 17 C of the intermediate shaft 17. In the illustrated embodiment, eight coils 23 are provided, wherein on each side of the region 17C four coils are arranged, which are in turn divided into two pairs. The coils 23 are each redundantly wired together and their signals are routed via a line 24 to a signal conditioning and processing unit 25. This can, for. B. accommodated or integrated in the hoist electronic 8.

The permanent magnetization of the region 17C of the intermediate shaft 17 or its magnetic field or the change in their orientation can be with outside of the shaft measure these special high-sensitivity coils 23 and the corresponding circuit.

Ideally, the torque transmitted by the individual transmission shafts depends, in addition to the fixed geometric variables, only on the load hanging on the hook 3.

However, this only applies to the static or the uniformly moving case. In contrast, in the accelerated movement, this must be taken into account when generating the torque on the cable drum 6. Likewise, the efficiencies based on friction (for example, rope rigidity and bearing friction) must be taken into account in the different directions of rotation, each with the corresponding sign. Depending on the desired accuracy and the circumstances, these parameters are taken into account in the signal conditioning unit 25.

Thus, in the determination of the lifting load by deformation of the intermediate gear shaft 17 under load their torsion, bending and tensile-pressure deformation can be considered. Here, the number, arrangement and interconnection and the evaluation of the sensors or coils 23 find input. When determining the torsion of the shaft 17, the material (modulus of elasticity, shear modulus and transverse contraction) and the geometry of the shaft are taken into account. In the determination of the transmitted torque, the translation and the efficiency are also included, taking into account the friction in bearings and seals and teeth and the viscosity of the oil in the transmission 4 in the evaluation of the signals. In the determination of the torque on the cable drum 6 itself, the friction z flows additionally. B. at the bearings of the cable drum 6 and the drum diameter in the evaluation. Finally, to calculate the lifting load, further parameters such as traction, shearing, rope geometry, statics, kinematics and efficiencies (eg friction losses of the rope pulleys) as well as the gravitational acceleration are incorporated.

The consideration of some parameters can be omitted depending on the desired accuracy. In particular, these are the bending and tension-compression deformation, the friction in bearings and seals and gearing and also the change in oil viscosity in the gearbox with temperature changes.

Claims (15)

1. A rope or chain hoist (1), comprising a hoisting gear mechanism (4), which has at least one rotating shaft (17), and a hoisting load measuring device (9, 17, 23, 24, 25),
   characterised in that the hoisting load measuring device has at least one sensor (9, 23) for detecting the deformation of the shaft (17) caused by the hoisting load within the hoisting gear mechanism (4) and the detected deformation is included as a variable for determining the hoisting load, and
   the sensor (9) determines the torsion of the shaft (17),
   the sensor (9, 23) for detecting the deformation of the shaft (17) determines the torque, the shaft (17) in the region (17C) situated opposite the sensor (9, 23) has at least one zone of permanent magnetisation, the magnetisation being oriented substantially longitudinally in the direction of the shaft axis and generating a magnetic field externally of the region which has a magnetic field component in a circumferential direction in relation to the shaft axis and is detected by the sensor (9, 23), and the shaft (17) is the shaft of the gear mechanism (4) with the smallest diameter.
2. A rope or chain hoist according to Claim 1, characterised in that the sensor (9, 23) is a magnetic field sensor.
3. A rope or chain hoist according to Claim 2, characterised in that the sensor (9, 23) operates in a magnetostrictive manner.
4. A rope or chain hoist according to any one of Claims 1 to 3, characterised in that the sensor (9, 23) detects the deformation contactlessly.
5. A rope or chain hoist according to Claim 4, characterised in that the shaft has in the region (17C) situated opposite the sensor first and second zones which are arranged in a ring shape around the shaft axis, the second zone being positioned radially inwardly of the first zone, one of the zones having permanent magnetisation which is oriented longitudinally in the direction of the shaft axis and the other zone provides a flux return path for the flux generated by the one zone, the one zone generating a magnetic field externally of the region which has a magnetic field component in a circumferential direction in relation to the shaft axis and is detected by the sensor (9, 23).
6. A rope or chain hoist according to any one of Claims 1 to 5, characterised in that a mounting (22) is provided for the arrangement of the sensor (9, 23) on the shaft (17), the said mounting at least partly embracing the said shaft.
7. A rope or chain hoist according to Claim 6, characterised in that the mounting (22) is fixed within and/or on the gear mechanism housing.
8. A rope or chain hoist according to any one of the preceding Claims, characterised in that 2 to 8 magnetic field-sensitive detectors, in particular coils (23), are respectively provided for each region in the sensor (9), which coils are arranged in particular uniformly around the region.
9. A rope or chain hoist according to any one of the preceding Claims, characterised in that the sensor (9, 23) is wired up in a redundant manner.
10. A rope or chain hoist according to any one of the preceding Claims, characterised in that a signal processing device (25) is provided for processing the signals from the sensor or sensors (9, 23).
11. A rope or chain hoist according to Claim 10, characterised in that the signal processing device (25) is provided in the control electronics (8) of the hoist (1).
12. A method for determining the hoisting load of rope or chain hoists according to any one of Claims 1 to 11, wherein the torsion of a rotating shaft (17) of the hoisting gear mechanism (4) caused by the hoisting load is detected in a hoisting load measuring device (9, 17, 23, 24, 25) of the hoist (1) and the torsion is used as a variable for determining the hoisting load.
13. A method according to Claim 12, characterised in that the torsion is detected by way of a contactlessly operating sensor (9, 23).
14. A method according to Claim 12 or 13, characterised in that the torsion is detected by means of magnetostrictive effects.
15. A method according to any one of Claims 12 to 14, characterised in that the torsion is detected by way of the torque.

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