WO2011128459A1

WO2011128459A1 - Mobile lifting device with electrohydraulic drive

Info

Publication number: WO2011128459A1
Application number: PCT/EP2011/056170
Authority: WO
Inventors: Andreas Hauck
Original assignee: Georg Kramp Gmbh & Co. Kg
Priority date: 2010-04-16
Filing date: 2011-04-18
Publication date: 2011-10-20
Also published as: DE102010015115A1

Abstract

The invention relates to a mobile lifting device (1) with an electrohydraulic drive and position control of the hydraulic cylinder (7), said drive and position control enabling simplified and safer use when lifting heavy loads. Furthermore, it is possible to synchronously control multiple lifting devices (1) via a common remote control and to ensure that the load is lifted by each lifting device (1) in a uniform manner as a result of the position control that is present on each lifting device.

Description

Mobiles Hebegerät mit elektro-hydraulischem AntriebMobile lifter with electro-hydraulic drive

Mobile lifters for lifting heavy loads, such as machine tools, presses, have been successfully marketed by the Applicant for decades. These lifting devices have a hydraulic cylinder to which a lever lug is attached and a hand-operated hydraulic pump. The hydraulic cylinder and the hydraulic pump are combined in a frame.

If you position such a lifting device with its lever ashes under the load to be lifted, then this load can be raised by operating the manual hydraulic pump. For larger loads several such lifting devices must be used if the load is to be raised evenly at all points or the lifting capacity of a lifting device is insufficient.

The invention has for its object to improve such a lifting device in terms of manageability, applicability and safety even further.

This object is achieved in that the hydraulic pump is driven by an electric motor. This makes it possible to lift the load regardless of the physical strength of the operator. At the same time, it can be ensured that, by means of a suitable torque limitation of the electric motor or via hydraulic pressure limiting valves, no loads that are too heavy are lifted by a lifting device. Thus, in a simple manner, the usability, but also the reliability of the mobile lifting device has been significantly improved.

In a further advantageous embodiment of the invention it is provided that means are provided for detecting a position of the hydraulic cylinder. These means for detecting the position of the hydraulic cylinder may be formed as a rotation angle sensor or as a magnetic system for detecting the revolutions, which detect the rotation angle or the number of revolutions of a positive displacement hydraulic pump or the electric motor. Alternatively, it is also possible that the position of the hydraulic cylinder is detected directly, for example via inductive or magneto-inductive distance or displacement sensors or a cable pull sensor.

Regardless of the operating principle of the means for detecting the position of the hydraulic cylinder, it is possible in this way to compare the stroke of several lifting devices used to increase a load with each other and to synchronize. This will ensure that all lifting equipment used to lift a load will make the same stroke. As a result, the load is raised in parallel, tilting or tilting of the load is excluded. In addition, it is ensured that the different lifting devices move in and out evenly under different load.

Namely, if one of the lifting devices would carry an unacceptably large proportion of the total load, then opens a pressure relief valve in the hydraulic part of the lifting device, so that the hydraulic cylinder drops slightly and as a result take over the other hydraulic cylinder a correspondingly higher load.

In a further advantageous embodiment of the invention, the hydraulic cylinder is designed as a double-acting hydraulic cylinder. This makes it possible to actively control the lifting and lowering of the load for each of the lifting devices used. As a result, it is ensured even when lowering the load that the load does not tip, but is lowered evenly. Furthermore, a better load distribution is achieved within the various lifting devices.

In order to further improve the handling of the mobile lifting devices according to the invention, it is provided that the electric motor is supplied with electrical energy by a rechargeable accumulator, preferably a lithium-ion accumulator. This eliminates the need for a power supply to the mobile lifting equipment and the lifting equipment can be operated anywhere, regardless of a power grid.

In a further advantageous embodiment of the invention, a control device is provided, which controls the electric motor in response to the signals of a remote control and / or the output signals of the means for detecting a position of the hydraulic cylinder. This makes it possible, via a remote control, which may be wired or wireless, the hydraulic cylinder by a defined amount on or extend. By the inventively provided means for detecting the position of the hydraulic cylinder, a position control can be performed so that the predetermined stroke is achieved with great accuracy.

In order to further simplify the use of the mobile lifting devices according to the invention and to make working with these lifting devices even safer, it is further provided that several lifting devices are controlled by a remote control. For then it is possible, for example, to arrange four independent lifting devices according to the invention at the four corners of a machine and to control all lifting devices with a remote control. This allows, together with the position controls of the lifting device according to the invention a uniform lifting of the machine. This avoids tilting the load.

A frequently occurring situation in practice is characterized in that the force application points of the lever ashtrays on a machine to be lifted are of different heights. In order to ensure a uniform lifting of the machine in these cases, can be inventively provided that the lever ashes are initially driven with a very small force from below to the load to be lifted. After the lifting lugs are in contact with the load, the individual positions of the hydraulic cylinders or the associated lifting lugs are stored as the zero point of the lifting operation in the control units of the lifting devices. This process of starting is done with such a low hydraulic pressure that the load is not raised thereby.

Only when in a second step via the remote control, the control signal to lift the load, the hydraulic cylinders are subjected to the full operating pressure and consequently raised the load. Now, if all participating lifting devices, starting from their individual zero point, have carried out the same stroke, it is ensured that, firstly, all lifting devices take up approximately the same load and, secondly, the load is lifted in parallel and without jamming. This positive effect is also present when the center of gravity of the load to be lifted is not in the middle between the lifting devices, but lies off-center.

This process of starting an individual zero point of the lever ashes of all involved lifting equipment is referred to as synchronizing before the start of the lifting process. During the lifting process, a further synchronization is made so that all lifters execute the same stroke. This synchronization takes place during the actual stroke and also when reaching the end position of the hydraulic cylinder when the load has been fully raised.

Independently or in addition to the communication of each lifting device with the remote control, the lifting devices can also communicate with each other wirelessly or by wire. This communication can be done during synchronization or during the lifting process. So when lifting the situation may occur that a single lifter is overloaded and as a result, the pressure in the hydraulic cylinder is reduced. This has the consequence that at least one adjacent lifting device is additionally loaded. If now also this neighboring lifter should be overloaded, it could come to an unwanted chain reaction. This can be prevented by a communication of the lifting devices with each other, for example, by all lifting equipment even settle the load to be lifted again.

The object underlying the invention is also achieved by a method for lifting heavy loads by means of at least two mobile lifting devices, wherein the mobile lifting devices are each equipped with a hydraulic cylinder, a hydraulic pump and means for detecting a position of the hydraulic cylinder. According to the invention it is provided that the hydraulic pump or the electric motor which drives the hydraulic pump, in response to the signals of a remote control and / or the output signals of the means for detecting a position of the hydraulic cylinder is driven.

This makes it possible to raise a load uniformly with the help of several hydraulic cylinders, so that the load to be lifted does not tilt and also all lifting devices are charged in the first approximation equal.

A load-independent and synchronous lifting of a load can be achieved according to the invention in that the number of revolutions of the electric motor or the number of pump strokes is the same for all lifting devices. This can be achieved by communication between the lifting devices with each other and / or with the remote control. For example, a further pump stroke can not be released until all lifting devices have communicated the execution of a pump stroke to the other lifting devices and / or the remote control. This makes it possible to uniformly and safely lift a load with unequal weight distribution.

In a further embodiment of the method according to the invention it is provided that before lifting the heavy load, the attached to the hydraulic cylinders lever pockets are brought into abutment with the load to be lifted and the case occupied by the hydraulic cylinders positions are used as reference points for the control of the subsequent lifting operation , For loads to be lifted, the points of force application for the lever ashes of the lifting devices are not always mounted at the same height, so that until the beginning of the actual lifting the hydraulic cylinders of the various lifting devices must be extended differently far.

If this operation takes place before the actual lifting with low working pressure in the hydraulic cylinders, in this way, the lifting tabs of the hydraulic cylinders are brought into abutment with the load to be lifted, without the load of the actual lifting takes place already to the effect that the load is lifted vertically and the load distribution is made uniform.

In a further advantageous embodiment of the method according to the invention, the lifting operation can be controlled away and / or force controlled. By means of a force control, it is possible to distribute the load on the various lifting devices so that none of the lifting devices is overloaded.

Further advantages and advantageous embodiments of the invention are the following drawings, the description and the claims removable. All of the features disclosed in the drawing, the description and the claims can be essential to the invention both individually and in any combination with one another.

drawing

Show it:

FIG. 1 shows an isometric illustration of an exemplary embodiment of a lifting device according to the invention with a wired remote control,

FIG. 2 shows a longitudinal section through the exemplary embodiment according to FIG. 1,

FIGS. 3 to 5 show different configurations of a plurality of lifting devices according to the invention used to lift a load;

Figure 6 is a hydraulic diagram of a lifting device according to the invention.

Description of the embodiments

1 shows a first embodiment of a lifting device 1 according to the invention with a wired remote control 3 is shown isometrically. The lifter 1 comprises a frame 5, a hydraulic cylinder 7 and a lever ashtray 9 fastened to the hydraulic cylinder 7. The lever tab 9 can be fixed in different positions on the hydraulic cylinder 7, depending on the height at which the load application points on the load to be lifted (not shown) ) available. On the frame 5, two feet 11 are attached, which ensure a secure state of the lifting device even at full load. On the frame 5, a hydraulic unit, a control unit and a power supply in the form of an accumulator 13 are arranged. The hydraulic power unit, comprising two electrically driven positive displacement pumps, a reservoir and various switching valves, and the control unit are covered in Figure 1 by a cover 15.

The accumulator 13 can be designed as a commercially available lithium-ion accumulator with an operating voltage of 14.4 V and a storage capacity of, for example, 2.2 ampere hours, as are known from cordless screwdrivers or other hand tools. A charging station for the accumulator 13 is not shown in FIG.

The work with the lifting device 1 according to the invention is very simple. In order to lift a load, the lever tab 9 is positioned below a suitable point of application of force against the load to be lifted. Subsequently, the hydraulic cylinder 7 is slightly extended via the remote control 3, so that the lever tab 9 comes from below in contact with the intended force application point on the load to be lifted. Subsequently, the actual lifting operation begins by the hydraulic cylinder 7 is extended via the remote control 3 so far until the load was raised by the desired stroke.

This procedure is already possible with conventional and commercially available lifting devices with manual hydraulic pump. However, it is required that the working pressure for the hydraulic cylinder 7 is applied by a hand pump, so that a person is required for this. Of course, this person can not at the same time monitor the actual lifting operation of a heavy and large machine, since it must be in close proximity to the lifter 1 to operate the hydraulic pump. Thus, the electro-hydraulic drive of the lifting device according to the invention already achieved a substantial work and an increase in occupational safety. The operator of the lifting device 1 can raise the load with sufficient safety distance to the load to be lifted via the remote control 3 while observing the lifting operation and in the event of unexpected occurring unexpected situations even cancel the lifting process.

FIG. 2 shows the lifting device 1 according to FIG. 1 in longitudinal section. The same components are provided with the same reference numerals, and the same applies with regard to FIG. 1.

The hydraulic cylinder 7 is designed as a double-acting hydraulic cylinder. The first working space 41, which is increased in volume for lifting the load, is not visible in FIG. 2, since it is formed between the upper end of a fixedly installed piston rod 17 and a top plate 19. In the lowest position of the hydraulic cylinder shown in Figure 2, the top plate 19 sits on the upper end of the fixed piston rod 17, so that the volume of the first working chamber 41 is zero in this position.

A first delivery line via which the first working space 41c is supplied with hydraulic oil is provided with the reference number 21 in FIG. A second working space 23 of the double-acting hydraulic cylinder 7 is supplied with hydraulic oil via a second delivery line 25. The second working space 23 is limited in the radial direction on the outside by a cylinder tube 27 and internally by the piston rod 17. Since double-acting hydraulic cylinders 7 have long been part of the prior art, a detailed structural description of the hydraulic cylinder 7 is omitted here.

It is important to point out, however, that the lever ashtray 11 is arranged only indirectly on the hydraulic cylinder 7 and a linear guide between the frame 5 and the movable part of the hydraulic cylinder 7 is provided, so that the hydraulic cylinder 7 no lateral forces resulting from the load to be lifted , must record.

In Figure 2, a reservoir 29 for the hydraulic fluid and various valves are arranged on the left of the hydraulic cylinder 7. Furthermore, an electric motor 31, which is preferably designed as an electronically or mechanically commutated DC motor, a transmission 33 and a hydraulic pump 35 are shown. The various main components, namely the hydraulic cylinder 7, the reservoir 29, and the hydraulic pumps 35 are connected to each other via a so-called valve plate 38, in which various valves are arranged.

Furthermore, a control unit 37 is still visible in Figure 2, which evaluates the output signals of the means, not shown, for detecting the position of the hydraulic cylinder and the electric motor 31 drives.

The electric motor 31 may be formed, for example, as an electronically commutated DC motor. In this case, a rotation angle sensor is present anyway in the electric motor 31, which according to the invention can also be used to detect the position of the hydraulic cylinder 7. This is possible because the hydraulic pump 35 is designed as a positive displacement pump, so that the volume of the first working space 41 and / or the second working space 23 of the hydraulic cylinder 7 can be determined depending on the number of revolutions which the electric motor 31 has performed. Depending on this, the position of the hydraulic cylinder 7 or the lever ashtray 9 can then also be determined. These calculations are performed by the controller 37 and used for a position control according to the invention of the lever ashtray 9 and the stroke of the hydraulic cylinder 7. Of course, other means for detecting the position of the hydraulic cylinder can be used. It is conceivable, for example, for a cable pull sensor to be used directly on the hydraulic cylinder or for a rotational angle sensor to be arranged on the shaft of the hydraulic pump. Since the position of the hydraulic cylinder 7 only needs to be detected with a comparatively low accuracy, many commercially available and also cost-effective position sensors can be used.

At the left in Figure 2 end of the frame 5, a roller 39 is provided, which make it possible to roll the lifting device 1 according to the invention to the place of use.

The electrohydraulic drive of the lifting devices 1 according to the invention and the position regulation of the lifting devices according to the invention make it possible to control a plurality of lifting devices with a remote control 3 and at the same time to ensure that the load to be lifted is lifted uniformly by the lifting devices 1 used.

FIG. 3 shows a first configuration in which two identical lifting devices 1 are controlled via a common remote control. The data exchange between the remote control 3 and the lifting devices 1 is wired via lines. Alternatively, it is of course also possible to establish wireless communication between the lifting devices 1 and the remote control 3. Because the controls of each lifter and remote control must operate independently of the number of lifters used, it is helpful to use a bus system such as a CAN bus to communicate information and communicate with the device. This bus system can work wired or wireless.

It is quite obvious from FIG. 3 that the load to be lifted can be doubled by inserting two structurally identical lifting devices 1. At the same time it is ensured that both lifting devices perform an equal stroke and thus the load to be lifted (not shown) is raised evenly.

FIGS. 4 and 5 show further configurations with three or four lifting devices 1 and one remote control 3, respectively.

The circuit diagram shown in Figure 6 showed a variant in the first working space 41 and the second working space 23 of the double-acting hydraulic cylinder 7 are each connected to its own hydraulic pump 35.1 and 35.2.

The hydraulic connection of both hydraulic pumps 35.1 and 35.2 is as follows:

The suction sides of the hydraulic pumps 35.1 and 35.2 are connected via suction lines 43.1 and 43.2 to the storage containers Via conveying

lines

21 and 25, the hydraulic pumps 35.1 and 35.2 convey hydraulic fluid into the working

spaces

41 or 23. Relief lines 45 branch off from the conveying

lines

21, 25 with a controllable pressure limiting valve 47. When the pressure relief valve 47 is open, the hydraulic fluid delivered by the hydraulic pump 35 is returned to the reservoir 29.

In both conveying

lines

21, 25 check valves 49 are provided, whose function is apparent from the circuit diagram. The check valve 49.6 can be unlocked by a connected to the feed line 21 auxiliary line 51, so that whenever there is a high pressure in the feed line 21, the check valve 49.6 is unlocked and consequently the second working space 23 is depressurized.

Of course, it would also be possible to supply the double-acting hydraulic cylinder 7 with a pump 35. For this the circuit diagram would have to be changed a bit. Since such circuits are well known, a detailed description will be omitted.

Claims

Mobile lifting device for lifting heavy loads, comprising a frame (5), a hydraulic cylinder (7) and at least one hydraulic pump (35), characterized in that the hydraulic pump (35) is driven directly or via a gear (33) by an electric motor (31). is driven.
Mobile lifting device according to one of the preceding claims, characterized in that means for detecting a position of the hydraulic cylinder (7) are provided.
Mobile lifting device according to claim 2, characterized in that the means for detecting a position of the hydraulic cylinder (7) are formed as a rotation angle sensor, and that the rotation angle sensor detects the rotation angle of a shaft of the hydraulic pump (35) or the electric motor (31).
Mobile lifting device according to claim 3, characterized in that the means for direct detection of a position of the hydraulic cylinder (7) are designed as a Hall sensor, and in that this Hall sensor, the number of revolutions of a shaft of the at least one hydraulic pump (35) or the at least one electric motor ( 31).
Mobile lifting device according to claim 2, characterized in that the means for direct detection of a position of the hydraulic cylinder (7) are designed as cable pull sensor or as inductive or magneto-inductive distance or displacement sensors.
Mobile lifting device according to one of the preceding claims, characterized in that the hydraulic cylinder (7) is designed as a double-acting hydraulic cylinder.
Mobile lifting device according to one of the preceding claims, characterized in that the electric motor (31) and a control device (37) of a rechargeable accumulator (13) is supplied with electrical energy.
Mobile lifting device according to one of the preceding claims, characterized in that a control device (37) is provided, which the electric motor (31) in response to the signals of a remote control (3) and / or the output signals of the means for detecting a position of the hydraulic cylinder ( 7).
Mobile lifting device according to one of the preceding claims, characterized in that a plurality of lifting devices (1) are controlled by a remote control (3).
Mobile lifting device according to claim 8, characterized in that the positions of the hydraulic cylinders (7) of the lifting devices (3) via the common remote control (3) and / or the control devices (37) of the lifting devices (1) are synchronized.
Mobile lifting device according to one of the preceding claims, characterized in that the lifting devices (1) have means for wireless or wired communication with each other.
Method for lifting heavy loads by means of at least two mobile lifting devices (1), the mobile lifting devices (1) each being equipped with a hydraulic cylinder (7), an electrically driven hydraulic pump (35) and means for detecting a position of the hydraulic cylinder (7) , characterized in that the hydraulic pump (35) or the electric motor (31) in response to the signals of a remote control (3) and / or the output signals of the means for detecting a position of the hydraulic cylinder (7) is driven.
A method according to claim 12, characterized in that prior to the lifting of the load on the hydraulic cylinders (7) mounted lifting lugs (9) are brought into abutment with the load to be lifted and thereby occupied by the hydraulic cylinders (7) positions as reference points for the Control of the subsequent lifting operation are taken.
A method according to claim 12 or 13, characterized in that the lifting operation is controlled away and / or force controlled.
Method according to one of claims 12 to 14, characterized in that the lifting members (1) communicate with each other and / or with the remote control (3).