Stator segment with deformable connecting 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 connecting element contains a deformable part, and the second connecting element contains a receiving region for receiving and holding the deformable part. The deformable part is deformed upon being inserted into the receiving region such that the first and second connecting element are connected together in a form-fitting manner.

Description

[0001] Stator segment with deformable connecting 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 comprises an arcuate ring section and a connecting device with a first and a second connecting element, wherein the first connecting element comprises a deformable portion and the second connecting element comprises a receiving area for receiving and holding the deformable portion, and wherein the deformable portion is deformed upon insertion into the receiving area such that the first and second connecting elements are positively connected to one another.

[0010] The deformable part can be plastic or elastic.

[0011] The fit can also be understood as the degree of fit or accuracy of fit.

[0012] According to a further advantageous embodiment, it may be possible for the connecting device to contain at least a first and a second undercut.

[0013] According to a further advantageous embodiment, it may be possible for the compensating element to at least partially contain a curable material. The curable material may be, for example, a polymer, synthetic resin, or the like.

[0014] According to a further advantageous embodiment, it may be possible for the first connecting element to be positioned at a free end of the arcuate ring section and the second connecting element to be positioned substantially at a first end of the web element.

[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 to create at least one positive, non-positive and / or material-locking connection to one another in a closed state. This makes it possible to connect the connecting elements in a simple manner. In this case, in addition to a mechanical connection, i.e. a positive or non-positive connection, it is also possible to provide a material-locking connection in the form of an adhesive between the adjacent ring sections. According to a further advantageous embodiment, it may be possible for the connecting device to be designed as a snap connection. This makes it possible to achieve a reliable and removable connection between the connecting elements in a simple manner.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] According to a further advantageous embodiment, it may be possible to provide an elastically or plastically deformable contact element between the first and second connecting elements. This makes it possible to easily achieve a reliable snap connection between adjacent connecting elements and to remove an individual tooth device from a stator assembly. Further advantages will become apparent from the following description of the figures. The figures illustrate various exemplary embodiments of the present invention.

[0022] The figures, the description, and the claims contain numerous features in combination. The skilled person will expediently consider the features individually and combine them into further meaningful combinations.

[0023] They show:

[0024] Figure 1 is a schematic side view of a machine tool with a drive according to an exemplary embodiment;

[0025] Figure 2 is a perspective side view of a stator and rotor as part of the drive;

[0026] Figure 3 is a perspective side view of the stator with a number of

[0027] dental equipment;

[0028] Figure 4 is a front view of two adjacent dental devices with a

[0029] Connecting device comprising a first and second connecting element according to a first embodiment in a separated state;

[0030] Figure 5 is a front view of two adjacent dental devices with a connecting device comprising a first and second connecting element according to the first embodiment in a connected state;

[0031] Figure 6a is a front view of two adjacent dental devices with a connecting device comprising a first and second connecting element according to a second embodiment in a separated state;

[0032] Figure 6b shows a front view of two adjacent tooth devices with a connecting device containing a first and second connecting element according to a second embodiment in a deformed state; and

[0033] Figure ? a front view of two adjacent dental devices with a connecting device containing a first and second connecting element according to the second embodiment in a final connected state. Examples of embodiments:

[0034] Figure 1 shows a machine tool 1 in the form of a cordless screwdriver according to an exemplary embodiment.

[0035] 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.

[0036] 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.

[0037] The housing 2 has a top side 2a, a bottom side 2b, a front end 2c and a rear end 2d.

[0038] 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).

[0039] 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.

[0040] 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.

[0041] 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.

[0042] In the present embodiment, the power supply 5 is designed as a rechargeable battery. According to an alternative embodiment not shown in the figures, the power supply 5 can also be designed as a power cable for releasably connecting the machine tool 1 to a mains power source (also called a power outlet).

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] As can be seen in the figures, 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.

[0050] Figure 4 shows a toothed device 20 according to a first embodiment, wherein 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 substantially to 1 / 4 or 25% of the volume of the first ring section 17.

[0051] In addition, each tooth device includes a connecting device 19 with a first and second connecting element 19a, 19b. 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.

[0052] In the present embodiment, the connecting device 19 is designed as a joining connection. The connecting device 19, designed as a joining connection, serves to detachably connect the individual ring sections 17, 18 and thus the individual toothed device 20 to form a continuous annular stator 13.

[0053] The first connecting element 19a on the first ring section 17 is configured with a deformable portion. The deformable portion can be plastic or elastic. In the first embodiment, the deformable portion of the first connecting element 19a is configured essentially in the form of a radially inwardly directed pin.

[0054] In Figure 4, the first connecting element 19a and in particular the plastically deformable portion of the first connecting element 19a is shown in an original or undeformed state.

[0055] The second connecting element 19b on the second ring section 18 is in turn designed as a receiving area which is designed to be able to receive the first connecting element 19a designed as a pin, see Figure 4. The volume of the receiving area is slightly larger than the volume of the pin, so that the undeformed pin can be positioned in the receiving area with some play.

[0056] In Figure 4, the first and second connecting elements 19a, 19b are shown in a separated state, wherein the first and second connecting elements 19a, 19b are not engaged with each other.

[0057] To connect the first and second connecting elements 19a, 19b, as indicated in Figure 4, the first connecting element 19a, designed as a pin, is brought downwards in the radial direction into the second connecting element 19b, designed as a receiving area. When the first connecting element 19a, designed as a pin, is located in the second connecting element 19b, designed as a receiving area, a certain force is exerted downwards in the radial direction on the first connecting element 19a, designed as a pin. This exerted force deforms the pin and takes on the shape of the receiving area, see Figure 5. The first and second connecting elements 19a, 19b are thus in a form-fitting connection.Furthermore, Figure 4 shows that the first connecting element 19a has a first contact surface 21a extending obliquely to a tooth segment plane E, and the second connecting element has a second contact surface 21b extending obliquely to the tooth segment plane E. When the first and second connecting elements 19a, 19b are connected to one another, a connecting line between the first and second contact surfaces runs obliquely to the tooth segment plane E.

[0058] Furthermore, the first and second connecting elements 19a, 19b each have a raised portion 23a, 23b. Each raised portion 23a, 23b extends radially, or outwardly, from the outer surface of the stator 13. The raised portion 23a on the first connecting element 19a contains a long circular arc, and the raised portion 23b on the second connecting element 19b contains a short circular arc. As can be seen in Figure 4, both the raised portion 23a, 23b of the first and second connecting elements 19a, 19b have a side surface that extends substantially radially outward.

[0059] However, the elevations 23a, 23b on the first and second connecting elements 19a, 19b can also have a circular arc of substantially equal length.

[0060] When the first and second connecting elements 19a, 19b are connected to one another, the two elevations 23a, 23b complement one another to form a substantially continuous elevation 23 on the outer surface of the stator 13, said continuous elevation 23 having a substantially rectangular cross-sectional area.

[0061] The continuous elevation 23 on the outer surface of the stator 13 serves for the correct orientation or alignment of the stator 13 during the assembly of a drive 10 for a machine tool 1.

[0062] Figure 6a shows a tooth device 20 according to a second embodiment in a separated state.

[0063] The tooth device 20 according to the second embodiment essentially corresponds to the first embodiment in Figure 5. In the second embodiment, the first ring section 17 also has a longer first circular arc KB1 than the second circular arc KB2 of the second ring section 18.

[0064] In contrast to the first embodiment, in the second embodiment, the deformable portion of the first connecting element 19a is essentially designed in the form of a ring. The ring has a circular opening.

[0065] In Figure 6b, a certain force is exerted downward in a radial direction on the first connecting element 19a, designed as a ring. This force deforms the ring into an elongated, elliptical shape so that it can be inserted into the second connecting element 19b, designed as a receiving area. The material of the first connecting element 19a is softer than the material of the second connecting element 19b, so that when the force is exerted downward in a radial direction, only the first connecting element 19a and not the second connecting element 19b deforms.

[0066] Figure 7 shows the first and second connecting elements 19a, 19b in a connected state. When the first connecting element 19a, designed as a ring, is completely located within the receiving area of ​​the second connecting element 19b due to the application of force, the first connecting element 19a, designed as a deformed ring, is returned to a certain circular ring shape by applying a certain force in the radial direction N. As a result, the first connecting element 19a adapts to the shape of the second connecting element 19b, so that the first and second connecting elements 19a, 19b are in a positive connection and are thus guided radially.

[0067] A cylindrical insert element in the form of a pin with a circular cross-sectional area is then inserted into the opening of the second connecting element 19b.

[0068] Reference symbol

[0069] 1 machine tool

[0070] 2 Machine tool housing

[0071] 2a Top of the machine tool housing

[0072] 2b Bottom of the machine tool housing

[0073] 2c front end of the machine tool housing

[0074] 2d rear end of the machine tool housing

[0075] 3 tool holder

[0076] 4 Handle

[0077] 4a upper end of the handle

[0078] 4b lower end of the handle

[0079] 4c Front of the handle

[0080] 4d Back of the handle

[0081] 5 Energy supply

[0082] 6 Tools

[0083] 7 operating switches

[0084] 8 Control device

[0085] 9 Machine tool interface

[0086] 10 Drive

[0087] 11 Gear device

[0088] 12 Drive shaft

[0089] 13 Stator

[0090] 14 Rotor

[0091] 15 coil winding

[0092] 16 web element

[0093] 16a first end of the web element

[0094] 16b second end of the web element

[0095] 17 first ring section

[0096] 17a first end of the first ring section

[0097] 17b second end of the first ring section 18 second ring section

[0098] 18a first end of the second ring section

[0099] 18b second end of the second ring section

[0100] 19 Connecting device

[0101] 19a first connecting element

[0102] 19b second connecting element

[0103] 20 Dental equipment

[0104] 21a first contact area

[0105] 21 b second contact surface

[0106] 23 Survey

[0107] 23a first survey

[0108] 23b second survey

[0109] E Tooth segment plane

[0110] M center

[0111] MA central axis

[0112] N radial direction

[0113] R circular ring

[0114] KB1 first circular arc

[0115] KB2 second circular arc

[0116] ZB 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) contains an arcuate ring section and a connecting device (19) with a first and a second connecting element (19a, 19b), wherein the first connecting element (19a) contains a deformable portion and the second connecting element (19b) contains a receiving area for receiving and holding the deformable portion, and wherein the deformable portion is deformed upon insertion into the receiving area such that the first and second connecting elements (19a, 19b) are positively connected to one another.

2. Stator (13) according to claim 1, characterized in that the first connecting element (19a) is positioned at a free end of the arcuate ring section and the second connecting element (19b) is positioned substantially at a first end of the web element (19a, 19b).

3. Stator (13) according to claim 1 or 2, characterized in that the connecting device (19) is designed as a joining connection.

4. Stator (13) according to at least one of claims 1 to 3, characterized in that the path length of the separating line of the joining connection between the first and second connecting element (19a, 19b) is longer than a width (ZB) of a tooth device (20).

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