Lifting magnet device for magnetic load receiving excavator, excavator, and method for lifting loads using such lifting magnet device

Abstract

The invention relates to a lifting magnet device for an excavator for picking up magnetic loads, comprising a spacer, a permanent magnet element, a lifting device, and a movable shielding device for shielding a magnetic field. The lifting magnet device further comprises a picking-up position and a release position, wherein the permanent magnet element is located closer to the spacer in the picking-up position than in the release position, and the permanent magnet element and / or the spacer are movable via the lifting device. Furthermore, the movable shielding device is located between the permanent magnet element and the spacer in the release position. The invention also relates to an excavator comprising a lifting magnet device and a method for lifting loads using an excavator.

Description

[0001] The present invention relates to a lifting magnet device for an excavator for receiving magnetic loads, an excavator comprising a lifting magnet device, and a method for lifting loads using a lifting magnet device.

[0002] The demolition of buildings and infrastructure structures generates large quantities of concrete rubble, most of which is reinforced concrete. To separate the reinforcing steel, also known as rebar, from the concrete, mobile excavators equipped with magnets are typically used.

[0003] Such lifting magnet devices for excavators, especially for removing reinforcing steel in construction debris, are known from the prior art.

[0004] Such lifting magnet devices, as described, for example, in CN 213802519 U or EP 2918732 B1, are typically operated by an electromagnet consisting of a coil and a steel core. The magnetic field is generated by a generator coupled to a hydraulic motor. The hydraulic motor is powered by the excavator's hydraulic fluid, requiring operating pressures of 200 bar to 350 bar and flow rates of up to 200 L / min. These high hydraulic flow rates necessitate excavators with an operating weight of 14 t or more. Only such large excavators possess a hydraulic system capable of supplying both the excavator itself and an attachment with such demanding requirements. However, these excavators are more expensive to operate and maintain than smaller ones. Furthermore, due to space constraints, such large excavators cannot be used on every construction site.

[0005] CN 211541264 U describes a lifting magnet device for excavators consisting of two adjacent permanent magnets. To release the load, one permanent magnet is rotated 180° so that the two magnets repel each other and the load is released. However, this also generates high forces within the lifting magnet device. Furthermore, the lifting magnet device must be sufficiently large to allow one permanent magnet to rotate within it.

[0006] CN 210163961 U describes a lifting magnet device for excavators consisting of a permanent magnet housed in a box and moved up and down by two hydraulic cylinders. To remove the magnetic load from the bottom of the box, the permanent magnet is lifted within the box. A portion of the magnetic load may remain attached to the box. To prevent this, the box would have to be uneconomically tall and the stroke of the two hydraulic cylinders uneconomically long.

[0007] The object of the invention is to overcome the disadvantages of the prior art. In particular, the lifting magnet device should be usable by excavators with a dead weight of less than 14 t, and no magnetic forces should act on the magnetic load when it is released.

[0008] The problem is solved by a lifting magnet device for an excavator for receiving magnetic loads, an excavator comprising a lifting magnet device and a method for lifting loads using an excavator.

[0009] In particular, the problem is solved by a lifting magnet device for an excavator for picking up magnetic, especially ferromagnetic, loads. The lifting magnet device comprises a spacer, a permanent magnet element having a height H, a lifting device, and a movable shielding device for shielding a magnetic field. The lifting magnet device further comprises a picking-up position and a release position, wherein the permanent magnet element has a smaller distance to the spacer in the picking-up position than in the release position. The permanent magnet element and / or the spacer are movable via the lifting device. The movable shielding device is located between the permanent magnet element and the spacer in the release position.

[0010] In this case, a lifting magnet device refers to a device that can be attached to an excavator and can lift a magnetic load using a permanent magnetic element.

[0011] In this context, an excavator refers to a construction machine used for loosening and / or moving materials. The magnetic load, particularly a ferromagnetic load, can include reinforcing steel or rebar, pieces of construction debris, or other magnetic objects. The magnetic load need not consist exclusively of magnetic components but can also contain non-magnetic elements.

[0012] The spacer serves to spatially separate the permanent magnet element from the load. The spacer may come into direct contact with the load during lifting. The spacer is preferably made of non-magnetic and wear-resistant material, such as manganese steel or chromium-nickel-molybdenum steel. The use of wear-resistant material can improve the service life of the lifting magnet device, as the spacer may come into direct contact with the magnetic load.

[0013] A permanent magnet element can consist of a single magnet or multiple magnets. The permanent magnet element serves to generate the magnetic field that is used to hold the magnetic load.

[0014] The lifting device serves to move the permanent magnet element and / or the spacer, thereby reaching the pickup and release positions. In the pickup position, the distance between the permanent magnet element and the spacer is smaller than in the release position. Due to this smaller distance, the magnetic load is attracted to the permanent magnet element. By increasing the distance between the permanent magnet element and the spacer in the release position, the magnetic attraction force acting on the load is weaker than in the pickup position.

[0015] A movable shielding device is a device that can be moved between the permanent magnet element and the spacer, thereby shielding the magnetic field of the permanent magnet from the load. Due to the combination of the shielding device and the increased distance between the load and the permanent magnet element, virtually no magnetic forces act on the load when it is released.

[0016] The permanent magnet element can be moved between the receiving and release positions via the lifting device. This offers the advantage that the spacer can be permanently installed, thus enabling a more robust design for the lifting magnet device.

[0017] In the receiving position, the distance D1 between the permanent magnet element and the spacer can be between 5 mm and 30 mm, preferably between 10 mm and 15 mm, and in the releasing position, the distance D2 between the permanent magnet element and the spacer can be between 1.5 times the height H and 3 times the height H, preferably 2 times the height H. In this case, the distances D1 and D2 between the permanent magnet element and the spacer correspond to the minimum distance between the permanent magnet element and the spacer.

[0018] Such a distance in the lifting position ensures secure handling of the magnetic load. This distance D2, in combination with the movable shielding device, guarantees minimal magnetic forces acting on the load, while maintaining a compact design for the lifting magnet. This prevents objects from becoming stuck to the lifting magnet. Increasing the distance D2 further is conceivable, but would result in a less compact design. Reducing the distance D2 is also possible, but would then provide less space for the movable shielding device.

[0019] The permanent magnet element can comprise at least one magnet made of a neodymium-iron-boron alloy. Magnets made of a neodymium-iron-boron alloy possess a high magnetic energy density, which enables a compact design of the permanent magnet element. This also allows for the lifting of heavy magnetic loads. Alternatively, the permanent magnet element can also comprise an aluminum-nickel-cobalt alloy, a samarium-cobalt alloy, bismanol, ferrite, or other materials with permanent magnetic properties.

[0020] The lifting device can be electrically, pneumatically, or hydraulically driven. This offers the particular advantage of allowing the use of flexible connections between the excavator and the lifting magnet if the lifting device is powered by an external energy source. This is especially beneficial when the lifting magnet's position is constantly changing. For example, transmitting hydraulic fluid or, in the case of pneumatic transmission, air via flexible lines is less complex than mechanical power transmission. The same applies to the use of flexible electrical cables.

[0021] The lifting device can be designed as a double-acting hydraulic cylinder and the lifting magnet device can include at least two hydraulic hose connections.

[0022] In this context, a double-acting hydraulic cylinder refers to a cylinder comprising two opposing piston surfaces that can be pressurized with hydraulic fluid. Hydraulic hose connections serve to supply the double-acting hydraulic cylinder with hydraulic fluid. The hydraulic cylinder can be supplied with hydraulic fluid via an internal or external hydraulic system. If an existing hydraulic system is used, the lifting magnet device does not require its own power supply and is therefore less complex. By using a double-acting hydraulic cylinder instead of a hydraulic motor, less hydraulic fluid is required to operate the lifting magnet device. Therefore, such a lifting magnet device can also be operated by excavators with an operating weight of less than 14 tons and thus with a less powerful hydraulic system.

[0023] The lifting magnet device can comprise a housing consisting of a housing wall, a housing base, and a housing cover, wherein the housing base can be designed as a spacer and wherein the permanent magnet element can be located within the housing. In this case, a housing refers to a casing that encloses the permanent magnet element. The housing preferably comprises a non-magnetic material such as stainless steel and serves to protect the permanent magnet element. The housing wall can be made of sheet metal. The housing cover preferably comprises a cover plate made of mild steel, the thickness of which is preferably 20 mm.

[0024] The lifting magnet device can include a shielding device that is stationary relative to the housing. This shielding device can be located on the inside or outside of the housing wall, or it can be formed as the housing wall itself. The stationary shielding device protects the magnetic field of the permanent magnet element from the outside of the housing. This prevents magnetic dust or small particles from accumulating on the lifting magnet device. Furthermore, it prevents the permanent magnet element from posing a risk to individuals with pacemakers, implanted defibrillators, or other implants.

[0025] The stationary shielding device and / or the movable shielding device may be made of ferromagnetic material, in particular ferromagnetic steel.

[0026] The use of ferromagnetic materials, due to their high magnetic permeability, enables efficient shielding of the magnetic field. The use of ferromagnetic steel allows for cost-effective shielding. Alternatively, materials such as mu-metals or ferromagnetic amorphous metals can also be used.

[0027] The movable shielding device can be positioned between the housing wall and the permanent magnet element. By positioning the movable shielding device between the housing wall and the permanent magnet element, the magnetic field can propagate unimpeded towards the ground and thus towards the load. This enables the lifting magnet device to handle a maximum load. Alternatively, the movable shielding device can also be positioned between the housing cover and the permanent magnet element or moved out of the housing.

[0028] The movable shielding device can be moved via a joint using a lifting mechanism. By using a joint, the permanent magnet element and the lifting mechanism can be moved with only one actuator. This minimizes the risk of a potential collision between the permanent magnet element and the movable shielding device. Furthermore, the use of only one actuator allows for a more compact design of the lifting magnet mechanism.

[0029] The movable shielding device can consist of at least two blades. In this case, a blade refers to a scoop-shaped shielding device. By using two or more blades, the overall size of the movable shielding device can be kept constant, while the size of the individual blades can be kept small. This allows for more flexible positioning of the movable shielding device in the receiving position and enables a compact design of the lifting magnet device.

[0030] A shovel can have a constant or variable thickness. Furthermore, a shovel can have a maximum thickness between 15 mm and 40 mm. Specifically, the shovel can have a maximum thickness of 18 mm, 22 mm, 27 mm, or 35 mm.

[0031] The lifting magnet device can include a quick-change attachment system. In this context, a quick-change attachment system is a device that allows the excavator operator to change attachments quickly without leaving the cab. This enables fast and safe mounting and dismounting of the lifting magnet device. Such a quick-change attachment system can be mounted on the housing cover of the lifting magnet device. Alternatively, the quick-change attachment system can also be mounted on the side of the housing of the lifting magnet device.

[0032] The problem is further solved by an excavator comprising a lifting magnet device as described above, an excavator arm, and a hydraulic system. The lifting magnet device is preferably connectable to the excavator arm by means of a quick-change device, and the hydraulic hose connections can be connected to the excavator's hydraulic system.

[0033] In this case, an excavator arm, also called a boom arm, refers to an arm-shaped structure of an excavator, which serves, among other things, to accommodate attachments.

[0034] A hydraulic system of an excavator is understood to be a system that uses a hydraulic pump, hydraulic fluid, and hydraulic cylinders to perform the movements of the excavator. The hydraulic pump serves to circulate the hydraulic fluid. It is also conceivable that the lifting magnet device can be connected to the excavator arm using a conventional device or is permanently attached to the excavator arm.

[0035] It is also conceivable that the lifting magnet device can be controlled via an external hydraulic system or via an integrated hydraulic system located within the lifting magnet device. Furthermore, it is conceivable that the lifting magnet device can be controlled via an internal or external pneumatic system or an internal or external electrical system.

[0036] The object of the invention is further achieved by a method for lifting loads using an excavator as described above. Picking up a load can include switching on the lifting magnet device, which moves the lifting magnet device into the picking-up position, extending the lifting device, and thereby moving the movable shielding device between the permanent magnet element and the housing wall, and moving the permanent magnet element towards the spacer.

[0037] This method enables the safe and efficient lifting of a magnetic load. The lifting magnet device can be activated by the excavator operator from the excavator cab. Alternatively, the lifting magnet device can be activated via a remote control. The movable shielding device can also be positioned between the housing cover and the permanent magnet element or removed from the housing.

[0038] Releasing the load can include switching off the lifting magnet device, which retracts the lifting device and thereby moves the movable shielding device between the permanent magnet element and the spacer and moves the permanent magnet element away from the spacer (4).

[0039] This method enables the safe and efficient release of a magnetic load. The lifting magnet device can be switched off by the excavator operator from the operator's cab, similar to the switch-on process. Alternatively, the lifting magnet device can be switched off via remote control. A gap is defined as any position that is not located between the permanent magnet element and the spacer.

[0040] The invention is explained in more detail in the following figures.

[0041] They show: FIG 1: Perspective view of a lifting magnet device with housing, FIG 2: Perspective view of a lifting magnet device without housing, FIG 3: Front view of a lifting magnet device in the receiving position, FIG 4: Sectional view of a lifting magnet device in the receiving position, FIG 5: Front view of a lifting magnet device in the release position, FIG 6: Sectional view of a lifting magnet device in the release position, FIG 7: FEM simulation of the magnetic flux density in the receiving position, FIG 8: FEM simulation of the magnetic flux density in the release position, FIG 9: Schematic representation of an excavator with a lifting magnet device.

[0042] Figure 1Figure 1 shows a perspective view of a lifting magnet device 1. The housing 12 consists of a housing wall 13, a housing cover 15, and a housing base 14. In this embodiment, the spacer 4 is designed as the housing base 14. The lifting magnet device 1 is attached to an excavator 2 (not shown) via the housing cover 15. The hydraulic cylinder (not shown) is operated via the hydraulic connections 11.

[0043] Figure 2 shows a perspective view of the in FIG 1 The lifting magnet device 1 shown is without housing 12. The lifting magnet device 1 is in the receiving position 8. In this embodiment, the lifting device 6 is designed as a double-acting hydraulic cylinder 10. The movable shielding device 7, which in this embodiment is designed as blades 18, is located between the permanent magnet element 5 (not visible) and the housing 12 (not shown, see figure). FIG 3 The shovels 18 are made of normal steel and have a maximum thickness of 22 mm.

[0044] Figure 3 shows a front view of the in FIG 2 The lifting magnet device 1 shown is without housing 12. The lifting magnet device 1 is in the receiving position 8. The permanent magnet element 5 has been extended via the lifting device 6. Furthermore, the movable shielding device 7, which in this embodiment is designed as blades 18, is located between the permanent magnet element 5 and the housing wall 13 (not shown). The movement of the movable shielding device 7 is also effected via the lifting device 6.

[0045] The lifting device 6 is movably connected to a bucket 18 by means of a joint 17. Each joint 17 consists of two legs (25, 26), with a first leg 25 rotatably connected to the lifting device 6 and a second leg 26 rigidly connected to a bucket 18. The two legs 25 and 26 are rotatably connected to each other. The buckets 18 are each mounted to rotate about an axis 27. By extending the lifting device 6, the buckets 18 can be rotated about the axes 27 by means of the joints 17.

[0046] Figure 4 shows a section of the in FIG 3 The lifting magnet device 1 shown is in the receiving position 8. This means that the distance D1 between the permanent magnetic element 5 and the spacer 4 is smaller than in the release position 9. In this embodiment, the distance D1 is 10 mm.

[0047] The lifting device 6 is designed as a double-acting hydraulic cylinder 10, which can be operated via the hydraulic connections 11. In this version, the permanent magnet element 5 consists of a neodymium-iron-boron alloy.

[0048] Figure 5 shows a front view of the in FIG 2 The lifting magnet device 1 shown is without housing 12. The lifting magnet device 1 is in the release position 9, in which the permanent magnet element 5 has been inserted via the lifting device 6. Furthermore, the movable shielding device 7, which in this embodiment is designed as blades 18, is located between the permanent magnet element 5 and the spacer 4 (not shown). The movement of the blades 18 is also effected via the lifting device 6 and the joints 17.

[0049] Figure 6 shows a section of the in FIG 5The lifting magnet device 1 shown is in the release position 9. This means that the distance D2 to the spacer 4 is greater than in the receiving position 8. In this configuration, the distance D2 is 160 mm.

[0050] In this embodiment, the permanent magnet element 5 consists of a neodymium-iron-boron alloy. The height H corresponds to the height of the permanent magnet element and is 94 mm in this embodiment.

[0051] Figure 7 shows an FEM simulation of the magnetic flux density of the in FIG 1 The lifting magnet device 1 shown is in the receiving position 8. The brightness of the simulation results corresponds to the magnetic flux density, with darker areas corresponding to a higher magnetic flux density.

[0052] In this embodiment, the distance D1 between the permanent magnet element 5 and the spacer 4 is 10 mm. The spacer 4, which in this embodiment is designed as the housing base 14, is made of non-magnetic, wear-resistant manganese steel. In this embodiment, the stationary shielding device 16 is located on the inner side 13a of the housing wall 13 and is made of mild steel.

[0053] Figure 8 shows an FEM simulation of the magnetic flux density of the in FIG 1 The lifting magnet device 1 shown is in the release position 9. The brightness of the simulation results corresponds to the magnetic flux density, with darker areas corresponding to a higher magnetic flux density.

[0054] In this embodiment, the distance D2 between the permanent magnetic element 5 and the spacer 4 corresponds to 160 mm.

[0055] Figure 9Figure 1 shows a schematic representation of an excavator 2 with a lifting magnet device 1, which lifts a magnetic load 24.

[0056] The lifting magnet device 1 is connected to the excavator arm 20 of the excavator 2 by means of a quick-change device 19. The hydraulic system of the excavator 21 is connected to the hydraulic connections 11 of the lifting magnet device 1 by means of hydraulic hoses 23. This allows the excavator operator to operate the lifting magnet device 1 from the operator's cab.

Claims

1. Lifting magnet device (1) for an excavator (2) for receiving a magnetic, in particular ferromagnetic, load (3) comprising: - a spacer (4) - a permanent magnetic element (5) comprising a height H - a lifting device (6) - a movable shielding device (7) for shielding a magnetic field characterized by the fact that the lifting magnet device (1) comprises a receiving position (8) and a release position (9), wherein the permanent magnetic element (5) in the receiving position (8) has a smaller distance (D1) to the spacer (4) than in the release position (9) and the permanent magnetic element (5) and / or the spacer (4) are movable via the lifting device (6) and the movable shielding device (7) is located between the permanent magnetic element (5) and the spacer (4) in the release position (9).

2. Lifting magnet device (1) for an excavator (2) according to claim 1, characterized by the fact thatthe permanent magnetic element (5) can be moved via the lifting device (6) into the receiving position (8) and the release position (9).

3. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that in the receiving position (8) the distance (D1) between permanent magnetic element (5) and spacer (4) is between 5 mm and 30 mm, preferably between 10 mm and 15 mm, and in the releasing position (9) the distance (D2) between permanent magnetic element (5) and spacer (4) is between 1.5*H and 3*H, preferably 2*H.

4. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the permanent magnetic element (5) comprises at least one magnet made of a neodymium-iron-boron alloy.

5. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact thatthe lifting device (6) can be driven electrically, pneumatically or hydraulically.

6. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the lifting device (6) is designed as a double-acting hydraulic cylinder (10) and the lifting magnet device (1) comprises at least two hydraulic hose connections (11).

7. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the lifting magnet device (1) comprises a housing (12) which includes a housing wall (13), a housing base (14) and a housing cover (15), wherein the housing base (14) is designed as a spacer (4) and wherein the permanent magnetic element (5) is located in the housing (12).

8. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact thatthe lifting magnet device (1) comprises a shielding device (16) that is immovable relative to the housing (12) and is located on the inside (13a) or outside (13b) of the housing wall (13) or is designed as a housing wall (13).

9. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the stationary shielding device (16) and / or the movable shielding device (7) consists of ferromagnetic material, in particular ferromagnetic steel.

10. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the movable shielding device (7) is located in the receiving position (8) between the housing wall (13) and the permanent magnetic element (5).

11. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact thatthe movable shielding device (7) can be moved via a joint (17) by means of a lifting device (6).

12. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the movable shielding device (7) comprises at least two blades (18).

13. Lifting magnet device (1) for an excavator (2) according to one of the preceding claims, characterized by the fact that the lifting magnet device (1) comprises a quick-change device (19).

14. Excavator (2) comprising a lifting magnet device (1) according to one of claims 1-13, an excavator arm (20) and a hydraulic system (21) characterized by the fact that the lifting magnet device (1) can preferably be connected to the excavator arm (20) by means of a quick-change device (19) and that the hydraulic hose connections (11) can be connected to the hydraulic system of the excavator (21).

15. Method for lifting loads using an excavator according to claim 14, characterized by the fact thatThe picking up of a load includes switching on the lifting magnet device (1), which moves the lifting magnet device (1) into the picking position (8), which extends the lifting device (6) and moves the movable shielding device (7) between the permanent magnet element (5) and the housing wall (13) and moves the permanent magnet element (5) towards the spacer (4).

16. Method for lifting loads using an excavator according to claim 14, characterized by the fact that The release of the load includes switching off the lifting magnet device (1), which retracts the lifting device (6) and thereby moves the movable shielding device (7) between the permanent magnetic element (5) and the spacer (4) and moves the permanent magnetic element (5) away from the spacer (4).

Images