Rotor with releasable magnets

Abstract

Rotor for an electric motor, in particular as a drive for a machine tool, containing a rotor body with a central opening for receiving and holding a shaft, the rotor body containing at least a first and a second cutout which are positioned opposite one another and about an axis of rotation and which are each designed at least for releasably receiving a magnet. A magnet holding device is provided, which is designed to releasably fix the at least first and second magnets in a respective cutout when the magnet holding device is at least partially inserted into the cutouts.

Description

[0001] Rotor with removable magnets

[0002] The present invention relates to a rotor for an electric motor, in particular as a drive for a machine tool, comprising a rotor body with a central recess for receiving and holding a shaft, wherein the rotor body contains at least a first and second recess positioned opposite one another about a rotation axis, each of which is designed at least for releasably receiving a magnet.

[0003] Furthermore, the present invention relates to an electric motor with a rotor.

[0004] Furthermore, the present invention relates to a machine tool with a rotor.

[0005] Electric motors (in particular as drives for machine tools) are known from the prior art, which essentially comprise a stator and a rotor rotatable relative to the stator in order to generate a torque.

[0006] Rotors, as components or parts of electric motors for power tools, typically have permanent magnets to form magnetic poles, which are fitted into corresponding recesses in a rotor core. The permanent magnets are usually permanently bonded to the rotor core.

[0007] In order to remove the permanent magnets from the rotor core for recycling purposes, the rotor core must be completely broken apart.

[0008] It is therefore an object of the present invention to solve the problem described above.

[0009] The object is achieved by the subject matter of independent patent claims 1, 6 and 7. Further advantageous embodiments of the subject matter according to the invention are contained in the corresponding dependent patent claims.

[0010] The object is achieved in particular by a rotor for an electric motor, in particular as a drive for a machine tool, comprising a rotor body with a central recess for receiving and holding a shaft, wherein the rotor body contains at least a first and a second recess positioned opposite one another about a rotational axis, each of which is designed at least for releasably receiving a magnet. According to the invention, a magnet holding device is provided which is designed for releasably fixing the at least first and second magnets in a respective recess when the magnet holding device is at least partially inserted into the recesses.

[0011] According to an alternative and advantageous embodiment, it may be possible for the magnet holding device to contain a flange element and at least a first and second pin element, wherein the first and second pin elements are designed for insertion into a recess and the flange element is designed for abutting against a rotor body end.

[0012] According to a further advantageous embodiment, it may be possible for the length of a pin element to be greater than the length of the rotor body, so that in a connected state a pin element projects beyond the rotor body in the axial direction.

[0013] According to a further advantageous embodiment, it may be possible for at least one circuit board to be included with at least a first and second holding element for releasably holding a free end of a pin element.

[0014] The circuit board can also be called a Hall board.

[0015] According to a further advantageous embodiment, it may be possible for a recess to contain an elongated portion and a semicircular portion, wherein a cross-sectional area of ​​the elongated portion substantially corresponds to a cross-sectional area of ​​a magnet and the cross-sectional area of ​​the semicircular portion substantially corresponds to a cross-sectional area of ​​a pin element.

[0016] Furthermore, the task is solved by an electric motor with a rotor.

[0017] Furthermore, the task is solved by a machine tool with a rotor.

[0018] Further advantages will become apparent from the following description of the figures. The figures illustrate various embodiments of the present invention.

[0019] The figures, the description, and the claims contain numerous features in combination. The skilled person will also expediently consider the features individually and combine them into further meaningful combinations.

[0020] They show:

[0021] Figure 1 shows a schematic side view of a machine tool according to the invention according to an exemplary embodiment with an electric motor; Figure 2 shows a front view of a stator and a rotor;

[0022] Figure 3 is a perspective view of the rotor according to a first embodiment;

[0023] Figure 4 is a front view of the rotor according to the first embodiment;

[0024] Figure 5 is a front view of the rotor according to a second embodiment;

[0025] Figure 6 is a front view of the rotor according to a third embodiment; and Figure ? is a front view of the rotor according to a fourth embodiment.

[0026] Examples of implementation:

[0027] Figure 1 shows a machine tool 1 according to an exemplary embodiment. The machine tool 1 is designed in the form of a cordless screwdriver.

[0028] According to an alternative embodiment, the machine tool can also be designed in the form of a saw, a grinder, a hammer drill or the like.

[0029] The machine tool 1 designed as a drilling machine essentially contains a housing 2, a handle s, a tool holder 4 and a power supply 5.

[0030] The housing 2 has a front end 2a, a rear end 2b, an upper end 2c and a lower end 2d.

[0031] The tool holder 4 is positioned at the front end 2a of the housing 2. The tool holder 4 serves to receive and hold a tool. The tool is not shown in the figures.

[0032] In the present embodiment, the tool can be designed in the form of a drill. A first end 3a of the handle 3 is positioned at the lower end 2d of the housing 2. An interface 6 is provided at the second end 3b of the handle 3.

[0033] As shown in Figure 1, the handle 3 has an activation switch 8 with which the machine tool 1 can be set to an activation state or a deactivation state.

[0034] The power supply 5 can be releasably attached to the interface 6. In the present embodiment, the power supply 5 is designed in the form of a rechargeable battery. The power supply 5 serves to supply the machine tool with electrical energy.

[0035] According to an alternative embodiment, the power supply 5 can also be configured as a power cable for connecting the machine tool 1 to a mains power source (socket). The power supply 5 configured as a power cable is not shown in the figures.

[0036] Inside the housing 2 there is essentially positioned an electric motor 9 as a drive, a transmission device 10, a drive shaft 11 and a control device 12.

[0037] The electric motor 9, the gear mechanism 10, the drive shaft 11, and the tool holder 4 are arranged relative to one another inside the housing 2 such that a torque generated in the electric motor 9 can be transmitted to the gear mechanism 10, the drive shaft 11, and ultimately to the tool holder 4 or to the tool. The control device 12 is connected to the activation switch 8, the battery interface 6, and the electric motor 9 via corresponding lines L.

[0038] The electric motor 9 is designed in the form of a brushless electric motor and essentially contains a stator 16 and a rotor 17, see Figure 2.

[0039] The power supply 5, designed as a rechargeable battery, can be detachably connected to the machine tool 1 to supply the machine tool 1 with electrical energy. The rechargeable battery 5 essentially contains a battery housing 20, a number of energy storage cells 13, a battery interface 14, and a control device 15.

[0040] The energy storage cells 13 can also be referred to as battery cells and are arranged inside the battery housing 20.

[0041] The battery housing 20 essentially contains a cover element 20a, four side walls 20b and a base element 20c.

[0042] The battery interface 14 is arranged on the outside of the cover element 20a and serves for the electrical or electronic as well as mechanical connection of the battery 5 to the machine tool 1 or a charging device.

[0043] The charging device is used to charge the accumulator 5 with electrical energy and is not shown in the figures.

[0044] For electrical or electronic connection, the battery interface 14 has a positive contact, a negative contact, and a communication contact. The positive and negative contacts serve to create an electrical circuit when the battery 5 is connected to a machine tool 1 or a charging device. The communication contact serves to send and receive data and information in the form of electrical signals.

[0045] Alternatively or additionally, the accumulator 5 may also contain radio communication (e.g. Bluetooth) or wireless communication.

[0046] The energy storage cells 13 serve to absorb, store, and re-release electrical energy. The energy storage cells 13 are cylindrical in shape and based on lithium-ion technology. Each energy storage cell 13 contains a contact device at one end, which serves to transmit electrical energy. The individual contact devices are connected to the control device 15 of the accumulator 5 via corresponding lines.

[0047] Alternatively, the energy storage cells 13 can also be based on another suitable technology. The cylindrical shape of the energy storage cells 13 is also optional, so any other suitable shape or geometry can be selected. In particular, it is also possible for the energy storage cells 13 to be designed as pouch cells.

[0048] It is also possible for the accumulator 5 to contain both cylindrical energy storage cells 13 and pouch cells. In particular, it is possible for the accumulator 5 to contain only a single cylindrical energy storage cell 13 and a single pouch cell.

[0049] The control device 15 regulates and controls various functions of the accumulator 5. These functions include, among others, controlling the absorption and release of electrical energy into and from the energy storage cells 13. Furthermore, the control device 15 controls the amount of electrical energy to be absorbed or released by the energy storage cells 13.

[0050] As indicated in Figure 2, the rotor 17 is positioned inside the stator 16 and is also designed to be rotatable relative to the stator 16.

[0051] As shown in Figure 3, the stator 16 contains a stator lamination stack 25 with six radially inwardly directed pole teeth 19. The stator lamination stack 25 essentially consists of a number of profiled sheets stacked one above the other. The profiled sheets are not shown individually in the figures.

[0052] Two pole teeth 19 are positioned opposite each other. According to an alternative embodiment, more or fewer than six pole teeth 19 can be provided. The pole teeth 19 serve to respectively accommodate a coil wire 21 to create a coil 24. The coils 24 are connected to the power supply 5 via the control device 12 in order to apply an electrical voltage to the coils 24. In other words, the coils 24 are energized. With the help of the coils 24, an alternating magnetic field MF is generated, which rotates the rotor 17.

[0053] As shown in the figures, the rotor 17 includes a cylindrical rotor body 18 with four magnets 22. In the present embodiment, the magnets 22 are designed as permanent magnets.

[0054] Furthermore, in the present embodiment, the rotor body 18 is designed as a rotor core 26. The rotor core 26 consists of a number of laminated sheets arranged in a row. The individual sheets of the rotor core 26 are not shown in the figures. Furthermore, the rotor body 18 contains a central recess 27 for receiving and holding a rotor shaft 28. The rotor body 18 further contains a number of cutouts 23, into each of which a magnet 22 can be inserted. Two cutouts 23 are positioned opposite one another around the central recess 27 or around a rotation axis R.

[0055] In addition, a magnet holding device 30 is provided, which is designed to releasably fix the magnets 22 in a respective recess 23.

[0056] As shown in Figures 5 and 6, the magnet holding device 30 according to an exemplary embodiment includes a flange element 31 and a number of pin elements 32.

[0057] In the exemplary embodiment shown, the flange element 31 is essentially circular with a central recess 33. The shape and diameter of the flange element 31 essentially correspond to the cross-sectional shape of the rotor laminated core 26. In the present exemplary embodiment, four pin elements 32 are provided. The number of pin elements 32 corresponds to the number of magnets 22 for the rotor 17. Each pin element 32 is elongated and contains a first end 32a and a second end 32b. A pin element 32 is positioned with the first end 32a on a surface of the flange element 31 such that a pin element 32 extends orthogonally from the surface of the flange element 31. As also shown in the figures, the four pin elements 32 are arranged on a common radius on the surface of the flange element 31.

[0058] As shown in Figure 6, each recess 23 includes an elongated portion 23a and a semicircular portion 23b. A cross-sectional area of ​​the elongated portion 23a substantially corresponds to a cross-sectional area of ​​a magnet 22.

[0059] Furthermore, a cross-sectional area of ​​the semicircular portion 23b essentially corresponds to a cross-sectional area of ​​a pin element 32.

[0060] Each recess 23 is consequently designed such that both a magnet 22 and a pin element 32 can be accommodated simultaneously.

[0061] Figure 4 shows a rotor 17 in an assembled state.

[0062] To assemble the rotor 17, the rotor lamination stack 26, the rotor shaft 28, the magnets 22, and the magnet holding device 30 are connected to one another. To do this, the magnets 22 are first pushed from a first end 26a of the rotor lamination stack 26 into the corresponding recesses 23 of the rotor lamination stack 26 in the direction of arrow A. Subsequently, the pin elements 32 of the magnet holding device 30 are also pushed from the first end 26a of the rotor lamination stack 26 into the recesses 23 in the direction of arrow A. The magnets 22 are located in the respective elongated portions 23a, and the pin elements 32 are located in the semicircular portions 23b. The recesses 23 are designed such that the magnets 22 and the pin elements 32 are positioned in the recesses 23 with minimal play. Next, the rotor shaft 28 is inserted into the corresponding central recess 27.

[0063] As shown in Figure 7, the respective length LS of a pin element 32 is greater than the length LR of the rotor body 18, so that in a connected state a pin element 32 projects beyond the rotor body 18 in the axial direction.

[0064] Optimally, a printed circuit board 34 can also be positioned at a second end 26b of the rotor lamination assembly 26. As indicated in the figures, the printed circuit board 34 is circular with a central recess 34a and a number of holding elements 35. In the present embodiment, the printed circuit board 34 has four recesses 34b, each of which serves to receive and hold the free ends of the pin elements 32 by means of a positive fit.

[0065]

[0066] 1 machine tool

[0067] 2 housings

[0068] 2a front end of the housing

[0069] 2b rear end of the housing

[0070] 2c upper end of the housing

[0071] 2d lower end of the housing

[0072] 3 Handle

[0073] 3a first end of the handle

[0074] 3b second end of the handle

[0075] 4 tool holder

[0076] 5 Energy supply

[0077] 6 Interface

[0078] 8 activation switches

[0079] 9 Electric motor

[0080] 10 Gear device

[0081] 11 Drive shaft

[0082] 12 Control device

[0083] 13 Energy storage cell

[0084] 14 Battery interface

[0085] 15 Control device

[0086] 16 Stator

[0087] 17 Rotor

[0088] 18 rotor body

[0089] 19 Pole tooth

[0090] 20 battery housings

[0091] 21 coil wire

[0092] 22 Magnet

[0093] 23 Recess of the rotor body

[0094] 24 Coil 25 Stator laminated core

[0095] 26 rotor lamination package

[0096] 26a first end of the rotor lamination pact

[0097] 26b second end of the rotor lamination package

[0098] 27 central recess of the rotor body

[0099] 28 Rotor shaft

[0100] 30 Magnetic holding device

[0101] 31 flange element

[0102] 32 pin element

[0103] 32a first end of the pin element

[0104] 32b second end of the pin element

[0105] 33 central recess of the flange element

[0106] 34 circuit board

[0107] 34a central recess of the circuit board

[0108] 34b Cutouts of the circuit board

[0109] 35 Holding element on circuit board

[0110] R rotation axis

[0111] LS Length of a pin element

[0112] LR Length LR of the rotor body

Claims

Patent claims 1. Rotor (17) for an electric motor (9), in particular as a drive for a machine tool (1), containing a rotor body (18) with a central recess for receiving and holding a rotor shaft (28), wherein the rotor body (18) contains at least a first and second recess (27) positioned opposite one another about a rotation axis (R), each of which is designed at least to releasably receive a magnet (22), characterized by a magnet holding device (30) which is designed to releasably fix the at least first and second magnets (22) in a respective recess (23) when the magnet holding device (30) is at least partially inserted into the recesses (23).

2. Rotor (17) according to claim 1, characterized in that the magnet holding device (30) contains a flange element (31) and at least a first and second pin element (32), wherein the first and second pin element (32) are designed for respective insertion into a recess (23) and the flange element (31) is designed for abutment against a rotor body end (26a).

3. Rotor (17) according to claim 1 or 2, characterized in that the length (LS) of a pin element (32) is greater than the length (LR) of the rotor body (18), so that in a connected state a pin element (32) projects beyond the rotor body (18) in the axial direction.

4. Rotor (17) according to at least one of claims 1 to 3, characterized in that at least one circuit board (34) with at least a first and second holding element (35) for releasably holding a free end of a pin element (32) is included.

5. Rotor (17) according to at least one of claims 1 to 3, characterized in that a recess (23) contains an elongated portion (23a) and a semicircular portion (23b), wherein a cross-sectional area of ​​the elongated portion (23a) substantially corresponds to a cross-sectional area of ​​a magnet (22) and the one Cross-sectional area of ​​the semicircular portion (23b) substantially corresponds to a cross-sectional area of ​​a pin element (32).

6. Electric motor (9) with a rotor (17) according to at least one of claims 1 to 5.

7. Machine tool (1) with a rotor (17) according to at least one of claims 1 to 5.

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