Electric motor and machine tool

Abstract

The present invention relates to an electric motor (9), in particular for a machine tool (1), wherein the electric motor (9) has a stator (16) and a rotor (17) which can be rotated about an axis of rotation (31), wherein the stator (16) has a first and a second end face (16a, 16b) and a plurality of pole teeth (25), wherein each of the pole teeth (25) is designed to receive at least one first winding (19) for forming a first coil (26) and at least one second winding (20) for forming a second coil (26), wherein at least one first contacting element (24a) is provided for contacting the at least one first winding (19) and at least one second contacting element (24b) is provided for contacting the at least one second winding (20), wherein the at least one first contacting element (24a) and the at least one second contacting element (24b) are arranged separately from one another on the stator (16).

Description

[0001] Hilti Aktiengesellschaft in Schaan

[0002] Principality of Liechtenstein

[0003] ELECTRIC MOTOR AND MACHINE TOOL

[0004] The invention relates to an electric motor, in particular for a machine tool, wherein the electric motor has a rotor rotatably arranged about a rotating axis and a stator with a series of toothed sections. The invention further relates to a machine tool with such an electric motor.

[0005] Background of the invention:

[0006] Stators are components of electric motors that have a series of toothed sections arranged radially around the rotor's axis of rotation, extending inwards or outwards and bounded along the axis of rotation by two opposing end faces. Between adjacent toothed sections, groove-like spaces and slot-like openings are provided for receiving windings of electrically conductive wires, with the windings being configured to form electrical coils around the toothed sections.

[0007] The maximum cross-section of the electrically conductive wire to be wound is essentially limited by the width of the slot-like opening and the winding method used, thus restricting the operating range in terms of rotor speed and power output. To extend these limits, it is common practice to create multiple windings, with at least one additional electrically conductive wire being inserted simultaneously or sequentially into the same position. The resulting coils are then connected in parallel or in series, so that the effective conductor cross-section of a coil is multiplied by the number of parallel conductors, or the effective number of turns in the coil is multiplied.

[0008] Typically, all wire ends and connecting wire loops of the windings are located in the area of ​​the same end face of the stator and are brought together there in common connecting or contacting elements according to a predetermined scheme and electrically connected to each other. For the electrical connection of the wire ends or wire loops of multiple windings, it is known to provide special connecting components whose contact surfaces must be adapted to accommodate the additional wires resulting from the multiple windings, thus rendering them unsuitable for use with single windings.

[0009] This can lead to differences in the manufacturing process and parameters between stators with single and multiple windings. In particular, multi-winding stators may require complex wire end routing or loops to achieve the desired configuration, which can increase the required installation space. Furthermore, if the connection or contact elements also include busbars for forming a coil configuration, the cross-sections of these busbars in multi-winding stators may need to be adapted to the increased effective conductor cross-section of a coil, which can also result in an increase in installation space.

[0010] The object underlying the present invention is to provide an electric motor that can be formed with both a single winding and multiple windings with minimal impact on the required installation space.

[0011] The problem is solved by the subject matter of the independent claims. Advantageous embodiments relating to the subject matter of the independent claims are found in the dependent claims.

[0012] Description of the invention:

[0013] According to a first aspect, an electric motor, particularly for a machine tool, is proposed. The electric motor has a stator and a rotor rotatable about an axis of rotation. The stator has a first and a second end face and several tooth-shaped sections or pole teeth, each pole tooth being configured to receive at least one first winding to form a first coil and at least one second winding to form a second coil. In particular, the first winding and the second winding can be made of wire. The electric motor can be designed as an internal rotor, in which the rotor is arranged in an opening of the stator, or as an external rotor, in which the stator is arranged in an opening of the rotor.

[0014] To enable the electric motor to be manufactured with minimal impact on the required installation space, whether with a single or multiple windings, at least one first contacting element for contacting the first winding and at least one second contacting element for contacting the second winding are provided, with the first and second contacting elements being arranged separately on the stator. This also allows for an increase in the number of components that can be used with both single and multiple windings, such as contacting elements, busbars, etc., and also optimizes key parameters in the manufacturing process, such as the steps for electrical contacting, the forces required to crimp the various elements, currents, and / or holding times during hot crimping.to maintain the electrode geometries for hot pressing, etc. Consequently, the stator can be manufactured with essentially the same components and / or manufacturing processes, with a single winding as well as with multiple windings.

[0015] In particular, the at least one first contacting element can be configured to electrically contact the wire or wire loop forming the first winding. Similarly, the at least one second contacting element can be configured to electrically contact the wire or wire loop forming the second winding. Furthermore, the at least one first contacting element and / or the at least one second contacting element can be configured to be electrically and / or mechanically connected, directly or indirectly (i.e., via another component), to a further element.

[0016] For example, at least one first contacting element can be located in the area of ​​the first end face of the stator, and at least one second contacting element can be located in the area of ​​the second end face of the stator.

[0017] Preferably, the at least one first contact element and / or the at least one second contact element can be arranged on a lateral surface of the stator. For example, in the case of an internal rotor, the at least one first contact element and / or the at least one second contact element can be arranged on an outer lateral surface of the stator, and in the case of an external rotor, on an inner lateral surface of the stator.

[0018] According to a further embodiment, the at least one first contacting element and the at least one second contacting element can be arranged opposite each other in an axial direction of the stator such that they are located in corresponding positions. In other words, the at least one first contacting element and the at least one second contacting element can be connected in an axial direction in a straight line parallel to the axis of rotation.

[0019] Furthermore, the first winding and / or the second winding can be formed by a single continuous electrically conductive wire.

[0020] Particularly advantageous is the ability to lay the wire in such a way that, after contact with at least one first contacting element and / or at least one second contacting element, the desired connection of the coils can be achieved without the use of additional busbars. In particular, the first winding and the second winding can form a continuous winding.

[0021] According to a further embodiment, the first winding can have a first winding pattern and the second winding a second winding pattern, wherein the first winding pattern is the same as or different from the second winding pattern. For example, the second winding pattern of the second winding can be modified compared to the first winding pattern of the first winding such that the at least one first contacting element for the first winding can be electrically connected to the correspondingly directly opposite at least one second contacting element of the second winding via the shortest path in the longitudinal direction parallel to the axis of rotation.

[0022] Furthermore, at least one first contacting element can be electrically connected to a first power electronics unit by means of a first connecting element and / or at least one second contacting element can be electrically connected to a second power electronics unit by means of a second connecting element.

[0023] For example, at least one first contacting element of the first winding can be electrically connected to the first power electronics by means of stranded wires, and / or at least one second contacting element of the second winding can be electrically connected to the same or another power electronics by means of further or separate stranded wires.

[0024] In particular, the first and second power electronics can be the same or different.

[0025] Furthermore, the first contact element and the second contact element can be formed as a single piece. In other words, the first and second contact elements can form one component.

[0026] The one-piece design of the first and second contact elements can further simplify the manufacturing and assembly process, as both contact areas can be integrated into a single component, eliminating the need for separate alignment, positioning, or fixing of two individual contact elements. This reduces not only the number of components required but also the process complexity, particularly with regard to pressing or welding the winding wires, the contacting of which previously required different components and sometimes adapted geometries.

[0027] Furthermore, the first contacting element and / or the second contacting element can be designed as a hook.

[0028] According to a further embodiment, the at least one first contacting element and the at least one second contacting element can be electrically connected to each other in such a way that an electrical parallel connection of the first coil with the second coil or an electrical series connection of the first coil with the second coil results. In particular, the switching element can be configured to switch between a parallel connection and a series connection of the first and second coils. Depending on the switching state, this can make it possible to double the effective conductor cross-section of the first and second coils while keeping the effective number of turns constant, or to double the effective number of turns of the first and second coils while keeping the effective conductor cross-section constant.

[0029] According to another aspect, a machine tool with an electric motor as described above is proposed. In particular, the machine tool can be detachably connected to a power supply device, wherein the power supply device is configured to supply the machine tool with electrical energy.

[0030] Further advantages arise from the following description of the figures. The figures, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0031] In the figures, identical and similar components are numbered with the same reference symbols.

[0032] They show:

[0033] Figure 1 shows a schematic sectional drawing through a preferred embodiment of a machine tool with an electric motor according to a first embodiment.

[0034] Figure 2 shows a schematic detailed sectional drawing through a preferred embodiment of a stator of the electric motor according to the first embodiment.

[0035] Figure 3 shows a schematic side view of the stator of the electric motor according to the first embodiment.

[0036] Figure 4 shows a schematic sectional view along line I Vl V in Fig. 3,

[0037] Figure 5 shows a schematic sectional view along line VV in Fig. 3.

[0038] Figure 6 shows a schematic side view of the stator of the electric motor according to a second embodiment.

[0039] Figure 7 shows a schematic side view of the stator of the electric motor according to a third embodiment, and

[0040] Figure 8 shows a schematic side view of the stator of the electric motor according to a fourth embodiment.

[0041] Examples of implementation and description of figures:

[0042] Figure 1 shows a machine tool 1 according to an exemplary embodiment. The machine tool 1 is designed in the form of a battery-powered drill.

[0043] According to an alternative embodiment, the machine tool can also be designed in the form of a saw, a grinding machine, a hammer drill, or the like. The machine tool 1 designed as a drilling machine essentially comprises a housing 2, a handle s, a tool holder 4, and a power supply 5.

[0044] The housing 2 has a front end 2a, a rear end 2b, a top end 2c and a bottom end 2d.

[0045] 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 6.

[0046] In the present embodiment, the tool 6 is designed in the form of a drill bit. A first end 3a of the handle 3 is positioned at the lower end 2d of the housing 2. A battery interface 7 is provided at the second end 3b of the handle 3.

[0047] 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.

[0048] The power supply 5 can be detachably attached to the battery interface 7. 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.

[0049] According to an alternative embodiment, the power supply 5 can also be designed as a power cable for connecting the machine tool 1 to a mains power source (socket). The power supply 5 designed as a power cable is not shown in the figures.

[0050] Inside the housing 2, essentially a drive 9, a gear unit 10, a drive shaft 11 and a control unit 12 are positioned.

[0051] The drive 9, the gear unit 10, the drive shaft 11, and the tool holder 4 are arranged inside the housing 2 in such a way that a torque generated in the drive 9 can be transmitted to the gear unit 10, the drive shaft 11, and finally to the tool holder 4 or to the tool 6. The control unit 12 is connected to the activation switch 8, the battery interface 7, and the drive 9 by means of corresponding lines 41.

[0052] The energy supply 5, designed as a battery, can be detachably connected to the machine tool 1 to supply the machine tool 1 with electrical energy. The battery 5 essentially comprises a battery housing 40, a number of energy storage cells 13, a battery interface 14, and a control unit 15.

[0053] The energy storage cells 13 can also be called battery cells and are arranged inside the battery housing 40.

[0054] The battery housing 40 essentially contains a lid element 40a, four side walls 40b and a bottom element 40c.

[0055] The battery interface 14 is located on the outside of the cover element 40a and serves to electrically or electronically as well as mechanically connect the battery 5 to the machine tool 1 or a charging device.

[0056] The charging device is used to charge the accumulator 5 with electrical energy. The charging device is not shown in the figures.

[0057] 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 are used to create a circuit when the battery 5 is connected to a machine tool 1 or a charging device. The communication contact is used to send and receive data and information in the form of electrical signals.

[0058] Alternatively or additionally, the accumulator 5 can also be used for radio communication (e.g.

[0059] Bluetooth) or wireless communication.

[0060] The energy storage cells 13 serve to absorb, store, and release electrical energy. The energy storage cells 13 are cylindrical and based on lithium-ion technology. Each energy storage cell 13 has a contact device at one end for transferring electrical energy. The individual contact devices are connected to the control unit 15 of the accumulator 5 via corresponding lines.

[0061] Alternatively, the energy storage cells 13 can also be based on another suitable technology.

[0062] The cylindrical shape of the energy storage cells 13 is also optional, so any other suitable shape or geometry can be chosen. In particular, it is also possible for the energy storage cells 13 to be designed as pouch cells.

[0063] It is also possible that the accumulator 5 contains both cylindrical energy storage cells 13 and pouch cells. In particular, it is possible that the accumulator 5 contains only a single cylindrical energy storage cell 13 and a single pouch cell.

[0064] The control unit 15 regulates and controls various functions of the accumulator 5. These functions include, among others, controlling the input and output of electrical energy to and from the energy storage cells 13. In addition, the control unit 15 controls the amount of electrical energy to be received or released by the energy storage cells 13.

[0065] The drive 9 is designed in the form of a brushless electric motor and essentially contains a stator 16 and a rotor 17.

[0066] The rotor 17 is positioned inside the stator 16 and is also designed to rotate relative to the stator 16. Alternatively, the stator can also be positioned inside the rotor, in which case the rotor is still designed to rotate relative to the stator.

[0067] Figure 2 shows a section of a first end face 16a of the stator 16 according to an exemplary embodiment. A second end face 16b of the stator 16 is arranged opposite the first end face 16a (see Figure 3).

[0068] The stator 16, shown as an example in the figures, contains a laminated core 18, a winding support 27, and six coils 26, each consisting of several first windings 19 made of a first winding wire 21 and several second windings 20 made of a second winding wire 22. The coil 26 can also be referred to as a winding coil. The electric motor 9 shown in the figures can be configured as a synchronous three-phase motor, with the winding wires 21, 22 (also referred to as power wires) representing the U-phase, V-phase, and W-phase.

[0069] Preferably, the winding wires 21, 22 are wound continuously. That is, the winding wires 21, 22 are not interrupted after a coil has been wound around one of the pole teeth. Particularly advantageously, the wires 21, 22 can be arranged such that, after contacting the wires with the first contacting elements 24a and / or the second contacting elements 24b, the desired connection of the coils 26 can be achieved without the use of additional busbars. For example, the first contacting elements 24a and / or the second contacting elements 24b can be designed as hooks.

[0070] The laminated core 18 essentially consists of a number of stacked profiled sheets. As can be seen in Figures 2, 4, and 5, six pole teeth 25 extend towards the center of the laminated core 18. The first and second winding wires 21 and 22 are wound around each individual pole tooth 25 to form the coil 26. At each of the respective ends 16a and 16b of the stator 16, the winding support 27 is arranged to support and hold the coil 26 wound from the winding wires 21 and 22.

[0071] The coils 26, or the first and second winding wires 21, 22, are coated with a plastic material that serves to insulate the coil 26. To supply the coils 26 with electrical energy, the wires 21, 22, which form a corresponding coil 26, must be contacted. In the proposed electric motor 9, this is achieved via contact elements 24. As can be seen in Figure 3, the electric motor 9 comprises three first contact elements 24a, which are arranged on a surface 23 of the stator 16 in the region of the first end face 16a, and three second contact elements 24b, which are also arranged on the surface 23, but in the region of the second end face 16b.

[0072] These contact elements 24a, 24b are designed to connect the wires forming each coil 26, with the first contact elements 24a contacting the wires of the first winding wire 21 and the second contact elements 24a contacting the wires of the second winding wire 22. Furthermore, the contact elements 24a, 24b can serve as connections for the power supply to the winding wires 21, 22 to generate the U-phase, V-phase, and W-phase during operation of the drive 9, which is designed as an electric motor.

[0073] As can be seen in Figure 3, the first and second contact elements 24a, 24b are arranged separately on the stator 16. This allows the first and second windings 21, 22 of the coil 26 to be connected independently of each other. This makes it possible to use the same components for the first and second contact elements 24a, 24b, so that the stator 16 can be manufactured with essentially the same components and / or manufacturing processes for both single and multiple windings. That is, it is not necessary to provide special contact elements designed to contact both the first winding wires 21 and the second winding wires 22 simultaneously.

[0074] Figure 6 shows a schematic side view of an electric motor 9 according to a second embodiment. In the embodiment shown in Figure 6, the first and second contact elements 24a, 24b are arranged opposite each other in an axial direction parallel to a rotational axis 31 of the rotor 17, such that they are located at corresponding positions around their circumference. This allows the opposing first and second contact elements 24a, 24b to be connected directly to each other in a straight line, for example, to a connecting element 33 (indicated by the dashed line). The connecting element 33 can be a busbar, a wire, a stranded wire, or the like.

[0075] In particular, in the embodiment shown in Figure 6, the first winding is designed in a first winding scheme and the second winding in a second winding scheme, differing in such a way that the first and second contacting elements 24a, 24b can be electrically connected in the shortest possible way in the longitudinal direction parallel to the axis of rotation 31.

[0076] For example, the first and second winding schemes can be chosen such that an electrical parallel connection of the first coil with the second coil or an electrical series connection of the first coil with the second coil results.

[0077] Figure 7 shows a schematic side view of an electric motor 9 according to a third embodiment. The electric motor 9 shown in Figure 7 according to the third embodiment differs from the electric motor 9 shown in Figure 6 according to the second embodiment in that the connecting elements 33 connect the first and second contacting elements 24a, 24b to a power electronics 35.

[0078] The power electronics 35 are specifically designed to supply current to the respective winding wires 21, 22. Furthermore, a switching element 37 can be provided, which is configured to switch between a parallel and a series connection of the first and second windings 21, 22. Depending on the switching state, this can allow the effective conductor cross-section of the first and second coils to be doubled while maintaining the same effective number of turns, or the effective number of turns of the first and second coils to be doubled while maintaining the same effective conductor cross-section. The switching element 37 can be integrated into the power electronics or provided separately.

[0079] Figure 8 shows a schematic side view of an electric motor 9 according to a fourth embodiment. The electric motor 9 shown in Figure 8 according to the fourth embodiment differs from the electric motor 9 shown in Figure 7 according to the third embodiment in that first connecting elements 33a connect the first contacting elements 24a to a first power electronics unit 35a, and second connecting elements 33b connect the second contacting elements 24b to a second power electronics unit 35b, which is different from the first power electronics unit 35a.

[0080] In the illustrated embodiments, three first and three second contact elements 24a, 24b are shown. However, it is also conceivable that the number of first and second contact elements 24a, 24b differs. It is also possible that the proposed electric motor 9 has one, two, four, or even six contact elements 24a, 24b.

[0081] In summary, the proposed electric motor, in addition to avoiding the aforementioned disadvantages of the prior art, allows a high degree of flexibility with regard to the interconnection of a first and second winding 19, 20 and their control by means of one or more power electronics.

[0082] A stator with multiple or double windings can be constructed using the same components as a stator with a single winding. This enables a modular stator design. The separate contacting of the first and second windings allows for the use of wires with a larger cross-section, even for multiple windings, as these wires are connected in separate contact elements.

[0083] 1 machine tool

[0084] 2 cases

[0085] 2a front end

[0086] 2b rear end

[0087] 2c upper end

[0088] 2d lower end

[0089] 3 handle

[0090] 3a first end

[0091] 3b second end

[0092] 4 Tool holder

[0093] 5 Energy supply

[0094] 6 tools

[0095] 7 Battery interface

[0096] 8 activation switches

[0097] 9 Electric motor

[0098] 10 Gearbox device

[0099] 11 Drive shaft

[0100] 12 Control unit

[0101] 13 energy storage cells

[0102] 14 Battery interface

[0103] 15 Control unit

[0104] 16 Stator

[0105] 16a first end

[0106] 16b second end

[0107] 17 Rotor

[0108] 18 sheet metal package

[0109] 19 first winding

[0110] 20 second winding

[0111] 21 winding wire

[0112] 22 winding wire

[0113] 23 Surface area

[0114] 24a first contacting element 24b second contacting element 25 pole tooth

[0115] 26 coil

[0116] 27 Changing support

[0117] 31 Rotation axis

[0118] 33 Connecting element 35 Power electronics 37 Switching element

[0119] 40 battery housings 40a cover element

[0120] 40b side wall

[0121] 40c floor element

[0122] 41 lines

Claims

Patent claims 1. Electric motor (9), in particular for a machine tool (1), wherein the electric motor (9) has a stator (16) and a rotor (17) rotatable about an axis of rotation (31), wherein the stator (16) has a first and a second end face (16a, 16b) and several pole teeth (25), wherein each of the pole teeth (25) is configured to receive at least one first winding (19) to form a first coil (26) and at least one second winding (20) to form a second coil (26), wherein at least one first contacting element (24a) is provided for contacting the at least one first winding (19) and at least one second contacting element (24b) for contacting the at least one second winding (20), wherein the at least one first contacting element (24a) and the at least one second contacting element (24b) are arranged separately from each other on the stator (16).

2. Electric motor (9) according to claim 1, wherein the at least one first contacting element (24a) is arranged in the region of the first end face (16a) of the stator (16) and the at least one second contacting element (24b) is arranged in the region of the second end face (16b) of the stator (16).

3. Electric motor (9) according to claim 1 or 2, wherein the at least one first contacting element (24a) and / or the at least one second contacting element (24b) are arranged on a lateral surface (23) of the stator (16).

4. Electric motor (9) according to one of the preceding claims, wherein the at least one first contacting element (24a) and the at least one second contacting element (24b) are arranged opposite each other in an axial direction such that they are located in corresponding positions circumferentially.

5. Electric motor (9) according to any one of the preceding claims, wherein the first winding (19) and / or the second winding (20) is formed by a single continuous electrically conductive wire (21, 22).

6. Electric motor (9) according to any one of the preceding claims, wherein the first winding (19) has a first winding scheme and the second winding (20) has a second winding scheme, wherein the first winding scheme is the same as or different from the second winding scheme.

7. Electric motor (9) according to one of the preceding claims, wherein the at least one first contacting element (24a) is electrically connected to a first power electronics (35a) by means of a first connecting element (33a) and / or the at least one second contacting element (24b) is electrically connected to a second power electronics (35b) by means of a second connecting element (33b).

8. Electric motor (9) according to claim 7, wherein the first and the second power electronics (35a, 35b) are the same or different.

9. Electric motor (9) according to one of the preceding claims, wherein the at least one first contacting element (24a) and the at least one second contacting element (24b) are electrically connected to each other in such a way that an electrical parallel connection of the first coil (26) with the second coil (26) or an electrical series connection of the first coil (26) with the second coil (26) is obtained.

10. Machine tool (1) with an electric motor (9) according to one of the preceding claims.

11. Machine tool (1) according to claim 10, wherein the machine tool (1) is detachably connectable to a power supply device (5), wherein the power supply device (5) is configured to supply the machine tool (1) with electrical energy.

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