Stator segments with insertable compensating element

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 can be connected together in a form-fitting manner such that in a connected state, at least one recess is provided between the first and second connecting element in order to receive a compensating element. The compensating element is designed to increase the fit between the first and second connecting element, and the recess contains at least one opening, which can be accessed in the radial direction, for inserting the compensating element.

Description

[0001] Stator segments with insertable compensating element

[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 second connecting element, wherein the first and second connecting elements can be connected to one another in a form-fitting manner such that, in a connected state, at least one recess is provided between the first and second connecting elements for receiving a compensating element, wherein the compensating element is designed to increase the fit between the first and second connecting elements and the recess contains at least one opening accessible in the radial direction for inserting the compensating 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 compensating element to at least partially contain a curable material. The curable material may be, for example, a polymer, synthetic resin, or the like.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.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.

[0017] Further advantages will become apparent from the following description of the figures. The figures illustrate various embodiments of the present invention.

[0018] 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.

[0019] They show:

[0020] Figure 1 shows a schematic side view of a machine tool with a drive according to an exemplary embodiment; Figure 2 shows a perspective side view of a stator and rotor as part of the drive;

[0021] Figure 3 is a perspective side view of the stator with a number of

[0022] dental facilities; and

[0023] Figure 4 is a front view of two adjacent dental devices with a connecting device containing a first and second connecting element according to an exemplary embodiment.

[0024] Examples of implementation:

[0025] Figure 1 shows a machine tool 1 in the form of a cordless screwdriver according to an exemplary embodiment.

[0026] 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.

[0027] 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.

[0028] The housing 2 has a top side 2a, a bottom side 2b, a front end 2c and a rear end 2d.

[0029] 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).

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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).

[0034] Furthermore, a drive 10, a gear mechanism 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 gear mechanism 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 gear mechanism 11, the drive shaft 12, and ultimately to the tool holder 3.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] The first connecting element 19a on the first ring section 17 is essentially designed in the form of a hook. The second connecting element 19b on the second ring section 18 is in turn designed as a raised portion corresponding to the hook, so that the first connecting element 19a can be engaged with the second connecting element 19b. As can be seen in Figure 4, the first connecting element designed as a hook encloses the second connecting element 19b designed as a corresponding raised portion, so that a positive connection is created between the first and second connecting elements 19a, 19b. The engagement of the first connecting element 19a in the second connecting element 19b connects the first and second ring sections 17, 18 to one another.

[0045] As shown in Figure 4, the first and second connecting elements 19a, 19b are each designed such that, in a connected state, a recess 30 remains between the first and second connecting elements 19a, 19b. The recess 30 serves to accommodate and hold a compensating element 31. The recess 30 is essentially designed in the form of an elongated gap between a first end face SF1 of the first connecting element 19a and a second end face SF2 of the second ring section 18. However, other designs for the recess 30 are also possible.

[0046] The compensating element 31 consists of a hardenable material, for example plastic or resin, and is introduced into the recess 30 in liquid form. In hardened form, the compensating element 31 remains in the recess 30. As a result, the compensating element 31 prevents the first and second connecting elements 19a, 19b from separating from one another again and, secondly, prevents the fit between the first and second connecting elements 19a, 19b from being increased. The compensating element 31 is brought into the recess 30 in the direction N. Furthermore, it can be seen in Figure 4 that the first connecting element 19a has a first contact surface 21a running obliquely to a tooth segment plane and the second connecting element 19b has a second contact surface 21b running obliquely to the tooth segment plane E.When the first and second connecting elements 19a, 19b are connected to each other, a connecting line between the first and second contact surfaces 21a, 21b runs obliquely to the tooth segment plane E.

[0047] 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.

[0048] However, the elevation on the first and second connecting elements 19a, 19b can also have a circular arc of substantially equal length.

[0049] 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.

[0050] The continuous elevation on the outer surface of the stator 13 serves for the correct orientation or alignment of the stator 13 during assembly to a drive 10 of a machine tool 1.

[0051] Reference symbol

[0052] 1 machine tool

[0053] 2 Machine tool housing

[0054] 2a Top of the machine tool housing

[0055] 2b Bottom of the machine tool housing

[0056] 2c front end of the machine tool housing

[0057] 2d rear end of the machine tool housing

[0058] 3 tool holder

[0059] 4 Handle

[0060] 4a upper end of the handle

[0061] 4b lower end of the handle

[0062] 4c Front of the handle

[0063] 4d Back of the handle

[0064] 5 Energy supply

[0065] 6 Tools

[0066] 7 operating switches

[0067] 8 Control device

[0068] 9 Machine tool interface

[0069] 10 Drive

[0070] 11 Gear device

[0071] 12 Drive shaft

[0072] 13 Stator

[0073] 14 Rotor

[0074] 15 coil winding

[0075] 16 web element

[0076] 16a first end of the web element

[0077] 16b second end of the web element

[0078] 17 first ring section

[0079] 17a first end of the first ring section

[0080] 17b second end of the first ring section 18 second ring section

[0081] 18a first end of the second ring section

[0082] 18b second end of the second ring section

[0083] 19 Connecting device

[0084] 19a first connecting element

[0085] 19b second connecting element

[0086] 20 Dental equipment

[0087] 21a first contact area

[0088] 21 b second contact surface

[0089] 23 continuous elevation

[0090] 23a first survey

[0091] 23b second survey

[0092] 30 recess

[0093] 31 Compensating element

[0094] E Tooth segment plane

[0095] SF1 first front face

[0096] SF2 second face

[0097] M center

[0098] MA central axis

[0099] N radial direction

[0100] R circular ring

[0101] KB1 first circular arc

[0102] KB2 second circular arc

[0103] 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 tooth device (20) each having a radially arranged web element for receiving a coil winding, characterized in that each tooth device (20) comprises an arcuate ring section and a connecting device (19) with a first and a second connecting element (19a, 19b), wherein the first and second Connecting elements (19a, 19b) can be connected to one another in a form-fitting manner such that, in a connected state, at least one recess (30) is provided between the first and second connecting elements (19a, 19b) for receiving a compensating element (31), wherein the compensating element (31) is designed to increase the fit between the first and second connecting elements (19a, 19b) and the recess contains at least one opening accessible in the radial direction for inserting the compensating element (31).

2. Stator (13) according to claim 1, characterized in that the compensating element (31) at least partially contains a hardenable material.

3. Stator (13) according to at least one of claims 1 to 2, 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.

4. Stator (13) according to at least one of claims 1 to 3, characterized in that the connecting device (19) is designed as a snap connection.

5. Stator (13) according to at least one of claims 1 to 3, characterized in that the connecting device (19) is designed as a joining connection.

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