Stator segments with clamping elements

Abstract

The invention relates to a stator for an electric motor, in particular as a drive for a machine tool, containing at least one first and second tooth device, each of which comprises a radially arranged web element for receiving a coil winding. Each tooth device contains an arched ring section and a connecting device with a first and second connecting element, wherein the first and second connecting element have a respective wedge-shaped design such that in a connected state, a first contact surface, which runs diagonally to a tooth segment plane, of the first connecting element rests against a second contact surface, which runs diagonally to the tooth segment plane, of the second connecting element. The first connecting element has a first elevation which faces radially outwards, and the second connecting element has a second elevation which faces radially outwards. The first connecting element is formed with a first undercut, and the second connecting element is formed with a second undercut, said undercuts being designed to receive and hold at least one clamping element.

Description

[0001] Stator segments with clamp elements

[0002] The present invention relates to a stator for an electric motor, in particular as a drive for a machine tool, comprising at least a first and a second tooth device, each with a radially arranged web element for receiving a coil winding.

[0003] Stators as a component for electric motors according to the state of the art essentially comprise a ring element and a number of toothed elements. The toothed elements extend from an inner surface of the ring element to a center point of the ring element. A circular free space remains at the free end of the toothed elements for a rotor. Each toothed element serves to accommodate and hold a wound coil on conductive coil wire to generate a magnetic field.

[0004] Especially for small stators, winding the individual tooth elements with coil wire is usually a complex technical undertaking. The available space between adjacent tooth elements is often limited, so quickly and, above all, neatly winding a coil around a tooth element requires a lot of time, requires a complex winding device, and is expensive.

[0005] It is therefore an object of the present invention to solve the problem described above.

[0006] The problem is solved by the subject matter of independent patent claim 1.

[0007] Advantageous embodiments of the subject matter of the invention are contained in the dependent claims.

[0008] The object is achieved in particular by a stator for an electric motor, in particular as a drive for a machine tool, comprising at least a first and a second tooth device, each with a radially arranged web element for receiving a coil winding.

[0009] According to the invention, each tooth device contains an arcuate ring section and a connecting device with a first and a second connecting element, wherein the first and second connecting elements are each wedge-shaped, so that in a connected state a first contact surface of the first connecting element running obliquely to a tooth segment plane bears against a second contact surface of the second connecting element running obliquely to the tooth segment plane, and wherein the first connecting element contains a first radially outwardly facing elevation and the second connecting element contains a second radially outwardly facing elevation, and wherein the first connecting element has a first undercut and the second connecting element has a second undercut, which are designed to receive and hold at least one clamp element.

[0010] The fit can also be understood as the degree of fit or accuracy of fit.

[0011] According to a further advantageous embodiment, it may be possible for the connecting device to contain at least a first and a second undercut.

[0012] According to a further advantageous embodiment, it may be possible for the first and second connecting elements to be designed such that a connecting line has both a section running obliquely to the tooth segment plane and a section running radially.

[0013] According to a further advantageous embodiment, it may be possible for the section running obliquely to the tooth segment plane to be longer than the radial section.

[0014] According to a further advantageous embodiment, it may be possible for the path length of the connecting line between the first and second connecting element to be longer than a width of a tooth device.

[0015] The dividing lines between the connecting points required to divide the tooth elements impair the magnetic circuit and the structural integrity of the stator as a whole. This can adversely affect the power density, stability, and / or noise behavior of the entire electric motor. Particularly in the case of dividing lines formed as punched edges, their negative influence on the electromagnetic properties of a stator lamination must be considered.

[0016] To minimize these disadvantages, it has proven advantageous that, according to a further alternative embodiment, at least one first connection point of the first and second connecting elements lies substantially in a plane through a toothed device. This allows a region of the magnetic circuit through the stator with a high magnetic flux density to lie in the radial extension of a toothed element, thereby optimizing the magnetic flux.

[0017] According to a further advantageous embodiment, it may be possible for the first and second connecting elements, in a closed state, to create at least one positive, non-positive, and / or material-to-material connection to one another. This allows a simple connection of the connecting elements. In addition to a mechanical connection, i.e., a positive or non-positive connection, it is also possible to provide a material-to-material connection in the form of an adhesive between the adjacent ring sections.

[0018] According to a further advantageous embodiment, it may be possible for the connecting device to be designed as a snap connection. This allows a reliable and removable connection of the connecting elements to be achieved in a simple manner.

[0019] According to a further advantageous embodiment, it may be possible for the connecting device to be designed as a joining connection. This allows a releasable connection of the connecting elements to be achieved in a simple manner, which does not require elastic deformability of the connecting elements or parts of the connecting elements. For releasable connection or separation, the connecting elements can simply be displaced relative to or against each other along a stator axis.

[0020] According to a further advantageous embodiment, it may be possible for at least a first dividing line of the joint between the first and second connecting elements to run parallel to a central axis of the stator, so that the first and second connecting elements can be displaced relative to one another and parallel to the central axis of the stator. This allows a relatively secure and resilient connection of the connecting elements to be achieved in a simple manner.

[0021] According to a further advantageous embodiment, it may be possible for the path of the separating line of the joining connection between the first and second connecting elements to be longer than the width of a toothed device. This results in the longest possible connecting line or separating line between adjacent connecting elements, whereby the magnetic flux between these adjacent connecting elements is minimally negatively affected.

[0022] Further advantages will become apparent from the following description of the figures. The figures illustrate various embodiments of the present invention.

[0023] 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.

[0024] They show:

[0025] Figure 1 is a schematic side view of a machine tool with a drive according to an exemplary embodiment;

[0026] Figure 2 is a perspective side view of a stator and rotor as part of the drive;

[0027] Figure 3 is a perspective side view of the stator according to an exemplary embodiment;

[0028] Figure 4 is a front view of the stator according to a first embodiment;

[0029] Figure 5 is a detailed view of the stator with toothed devices and arcuate first and second ring sections according to the first embodiment;

[0030] Figure 6 is a front view of the stator according to a second embodiment; and

[0031] Figure 7 is a detailed view of the stator with toothed devices and arcuate first and second ring sections according to the second embodiment.

[0032] Examples of implementation:

[0033] Figure 1 shows a machine tool 1 in the form of a cordless screwdriver according to an exemplary embodiment.

[0034] Alternatively, the machine tool 1 can also be designed in the form of a hammer drill, combination hammer, drilling machine, saw, grinder or the like.

[0035] As shown in Figure 1, the machine tool 1 according to the exemplary embodiment essentially contains a housing 2, a tool holder 3, a handle 4 and a power supply 5.

[0036] The housing 2 has a top side 2a, a bottom side 2b, a front end 2c and a rear end 2d.

[0037] Positioned at the front end 2c of the housing 2 is the tool holder 3, which serves to receive and hold a tool 6. In the present case, the tool 6 is designed as a screwdriver bit (or simply called a bit).

[0038] The handle 4 serves to hold and guide the machine tool 1 by a user (not shown in the figures). The handle 4 has an upper end 4a, a lower end 4b, a front side 4c, and a rear side 4d. The upper end 4a of the handle 4 is connected to the underside 2b of the housing 2 of the machine tool 1.

[0039] As can be seen in Figure 1, an actuating switch 7 is positioned on the front side 4c of the handle 4. The actuating switch 7 serves to activate the machine tool 1. A control device 8 of the machine tool 1 is positioned inside the handle 4 and serves to control and regulate the functions of the machine tool 1.

[0040] A foot device 8 with a machine tool interface 9 is provided on the underside 2b of the housing 2 of the machine tool 1. The machine tool interface 9 serves to releasably connect the machine tool 1 to the power supply 5.

[0041] In the present embodiment, the power supply 5 is configured as a rechargeable battery. According to an alternative embodiment not shown in the figures, the power supply 5 can also be configured as a power cable for releasably connecting the machine tool 1 to a mains power source (also called a power outlet).

[0042] Furthermore, a drive 10, a transmission device 11, and a drive shaft 12 are provided inside the housing 2 of the machine tool 1. In the present embodiment, the drive 10 is configured as an electric motor and serves to generate torque. The drive 10, configured as an electric motor, the transmission device 11, and the drive shaft 12 are arranged or positioned relative to one another in the housing 2 such that a torque generated by the drive 10 can be transmitted via the transmission device 11, the drive shaft 12, and ultimately to the tool holder 3.

[0043] The drive 10 essentially contains a stator 13 and a rotor 14 positioned in the stator 13 and rotatable relative to the stator 13, see Figure 2. The rotor 14 rotates about a central axis MA of the stator 13.

[0044] As can be seen in Figures 3 to 5, the stator 13 according to the exemplary embodiment contains six tooth devices 20. According to alternative embodiments, the stator 13 can also contain more or fewer than six tooth devices 20.

[0045] Each individual toothed device 20 serves to accommodate a coil winding 15 made of a conductive wire. The material of the conductive wire can be, for example, copper or a copper alloy.

[0046] Each tooth device 20 includes a web element 16 as well as an arcuate first ring section 17 and second ring section 18. As can be seen in Figures 3 and 4, the individual ring sections 17, 18 form a closed, circular ring R when combined.

[0047] The web element 16 has a first end 16a and a second end 16b, with the coil winding 15 being mounted between the first and second ends 16a, 16b. The respective first end 16a of the web element 16 is positioned on an inner surface of the ring R formed by the individual ring sections 17, 18. The second end 16b of the web element 16 projects to a center point M of the ring R. The length of the web elements 16 is selected such that a circular recess remains inside the stator 13. The rotor 14 can be placed in this recess.

[0048] As can be seen particularly in Figures 4 to 7, both the first and second ring sections 17, 18 each have a first and second end 17a, 17b, 18a, 18b. The first end 17a of the first ring section 17 is positioned at the first end 16a of the web element 16. The first end 18a of the second ring section 18 is also positioned at the first end 16a of the web element 16. The two ring sections 17, 18 extend in opposite directions around the ring R. The first ring section 17 has a longer first circular arc KB1 than the second circular arc KB2 of the second ring section 18. In other words, the first ring section 17 has a larger volume than the second ring section 18. In the illustrated embodiment, the volume of the second ring section 18 corresponds essentially to 1 / 3 or 30% of the volume of the first ring section 17.According to alternative embodiments (not shown in the figures), the volume of the second ring section 18 may also correspond to more or less than 1 / 3 or 30% of the volume of the first ring section 17.

[0049] Furthermore, a connecting device 19 with a first and second connecting element 19a, 19b is provided on the first and second ring sections 17, 18. The first connecting element 19a is positioned on the first ring section 17, and the second connecting element 19b is positioned on the second ring section 18.

[0050] The first and second connecting elements 19a, 19b are each wedge-shaped. When the first and second connecting elements 19a, 19b are connected, a first contact surface 21a of the first connecting element 19a, which extends obliquely to a tooth segment plane, rests against a second contact surface 21b of the second connecting element 19b, which extends obliquely to the tooth segment plane E.

[0051] As can also be seen in the figures, the first connecting element 19a contains a first radially outwardly facing elevation 22a and the second connecting element 19b contains a second radially outwardly facing elevation 22b.

[0052] Figures 4 and 5 show the stator 13 and the connecting device 19 according to a first embodiment. As can be seen in particular in Figure 5, the first elevation 22a of the first connecting element 19a is designed with a semicircular cross-sectional area and has a first substantially straight end face 25a. The second elevation 22b of the second connecting element 19b is also designed with a semicircular cross-sectional area and has a second substantially straight end face 25b. The first and second elevations 22a, 22b are configured to correspond such that the two elevations 22a, 22b form a continuous semicircular elevation 26 in a connected state (as shown in Figure 5), when the first and second end faces 25a, 25b are in contact with one another.

[0053] Furthermore, the first connecting element 19a contains a first undercut 23a and the second connecting element 19b contains a second undercut 23b. The first and second undercuts 23a, 23b are designed to receive and hold a clamp element 24. The clamp element 24 has a first end 24a and a second end 24b. The clamp element 24 is brought from a substantially straight state into a bent state. In the bent state, the clamp element 24 is connected to the first and second connecting elements 19a, 19b. The first end 24a of the clamp element 24 then projects into the first undercut 23a and the second end 24b of the clamp element 24 projects into the second undercut 23b. The clamp element 24 is held on the connecting device 19 by the first and second undercuts 23a, 23b. At the same time, the clamp element 24 serves to hold together the first and second connecting elements 19a, 19b.

[0054] Figures 6 and 7 show the stator 13 and the connecting device 19 according to a second embodiment. The connecting device 19 according to the second embodiment differs from the connecting device 19 according to the first embodiment in that the first elevation 22a of the first connecting element 19a has a substantially rectangular cross-sectional area and the second elevation 22b of the second connecting element 19a also has a substantially rectangular cross-sectional area. When the first and second connecting elements 19a, 19b are connected to one another, the two connecting elements 19a, 19b form a semicircular recess 27 between them. A material-to-material connection in the form of a welded or adhesive connection can be accommodated in this recess 27. No material-to-material connection between the first and second connecting elements 19a, 19b is shown in the figures.As can be seen particularly in Figures 4 to 7, a connecting line VL or the joining point of the connecting device 19 lies approximately in a tooth segment plane E through a tooth device 20.

[0055] Reference symbol

[0056] 1 machine tool

[0057] 2 Machine tool housing

[0058] 2a Top of the machine tool housing

[0059] 2b Bottom of the machine tool housing

[0060] 2c front end of the machine tool housing

[0061] 2d rear end of the machine tool housing

[0062] 3 tool holder

[0063] 4 Handle

[0064] 4a upper end of the handle

[0065] 4b lower end of the handle

[0066] 4c Front of the handle

[0067] 4d Back of the handle

[0068] 5 Energy supply

[0069] 6 Tools

[0070] 7 operating switches

[0071] 8 Control device

[0072] 9 Machine tool interface

[0073] 10 Drive

[0074] 11 Gear device

[0075] 12 Drive shaft

[0076] 13 Stator

[0077] 14 Rotor

[0078] 15 coil winding

[0079] 16 web element

[0080] 16a first end of the web element

[0081] 16b second end of the web element

[0082] 17 first ring section

[0083] 17a first end of the first ring section

[0084] 17b second end of the first ring section 18 second ring section

[0085] 18a first end of the second ring section

[0086] 18b second end of the second ring section

[0087] 19 Connecting device

[0088] 19a first connecting element

[0089] 19b second connecting element

[0090] 20 Dental equipment

[0091] 21a first contact area

[0092] 22b second contact surface

[0093] 22a first survey

[0094] 22b second survey

[0095] 23a first undercut

[0096] 23b second undercut

[0097] 24 clamp element

[0098] 24a first end of the clamp element

[0099] 24b second end of the clamp element

[0100] 25a first front face

[0101] 25b second front face

[0102] 26 continuous elevations

[0103] 27 semicircular recess

[0104] E Tooth segment plane

[0105] M center

[0106] MA central axis

[0107] N radial direction

[0108] R circular ring

[0109] VL connecting line

[0110] KB1 first circular arc

[0111] KB2 second arc

[0112] BZ width of the tooth device

Claims

Patent claims 1. Stator (13) for an electric motor, in particular as a drive for a machine tool, comprising at least a first and a second toothed device (20), each with a radially arranged web element for receiving a coil winding, characterized in that each toothed device (20) comprises an arcuate ring section (17, 18) and a connecting device (19) with a first and a second connecting element (19a, 19b), wherein the first and second connecting elements (19a, 19b) are each wedge-shaped, so that in a connected state, a first contact surface (21a) of the first connecting element (19a), which extends obliquely to a tooth segment plane (E), bears against a second contact surface (21b) of the second connecting element (19b), which extends obliquely to the tooth segment plane (E),and wherein the first connecting element (19a) includes a first radially outwardly facing elevation (22a) and the second connecting element (19b) includes a second radially outwardly facing elevation (22b), and wherein the first connecting element (19a) includes a first undercut (23a) and the second connecting element (19b) includes a second undercut (23b), which are designed to receive and hold at least one clamp element (24).

2. Stator (13) according to claim 1, characterized in that the first and second connecting elements (19a, 19b) are designed such that a connecting line (VL) has both a section running obliquely to the tooth segment plane (E) and a section running radially.

3. Stator (13) according to claim 1 or 2, characterized in that the section running obliquely to the tooth segment plane (E) is longer than the radially running section.

4. Stator (13) according to at least one of claims 1 to 5, characterized in that the path length of the connecting line (VL) between the first and second connecting element (19a, 19b) is longer than a width (BZ) of a toothed device (20).

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