Motor with yoke winding

Abstract

The invention relates to an electric machine, in particular an electric motor, having an encapsulated magnetic air gap and having windings of a loop ring of a stator instead of pole shoes. The invention also relates to a method for producing an electric machine.

Description

Field of the Invention

[0001] The present invention relates to an electric machine having a ring-shaped winding (yoke winding) with a stator circuit, and more particularly to a brushless electric machine. Background Art

[0002] Brushless motors belong to the prior art. They include widely spread asynchronous motors and mainly permanent magnet excited synchronous motors, which are also increasingly used in power tools due to their high power density.

[0003] Power tools transmit high continuous power, so the power semiconductors of the motor and the electronic device must be cooled. The preferred cooling medium is ambient air, but due to most of the machining processes of power tools, this ambient air contains dust. The compromise between cooling and dust prevention can be achieved by different dust filters or by components with appropriate encapsulation. Especially during metalworking, dust that can conduct electricity and magnetism is generated. Angle grinders generate particularly fine dust. But mineral or organic dust (wood) can also block the cooling air path inside the machine. Therefore, the dusty ambient air is a disturbing variable that limits the service life. As a result, repairs and maintenance are required.

[0004] For brushless drives, due to the open poles in the magnetic circuit, the magnetic air gap between the rotor and the stator is a key area for dust that needs to be encapsulated. Known structures encapsulate the entire motor. Thereby, the stator windings with particularly high losses are also encapsulated together, and there are disadvantages compared with structures in which only the air gap is separated from the cooling air. This structure seals the air gap by injection molding or by pushing wedges into the slots. The strategy of encapsulating the drive components has proven effective especially for angle grinders.

[0005] There are various strategies to deal with the dust in the ambient air. This situation often occurs, but not only in one's own machining process. That is, machines that only produce coarse chips themselves but are used at a usage site where, for example, adjacent grinding operations are performed also face risks. Therefore, this problem exists not only for power tools such as angle grinders.

[0006] Contrary to the commonly used strategy of keeping dust away from the machine interior with a dust guard, dust sometimes also passes through the largest possible gap sizes and guides through the encapsulated components.

[0007] There is also the following method: filtering the dust in the machine interior from the air and thus using clean air for cooling, without the need for complete encapsulation (such as the cyclone principle), but exactly the particularly fine dust poses a danger, and the above method is only effective in the case of a rotating drive. However, even when the machine is shut down, dust exists inside and invades the openings due to position changes.

[0008] It seems to be a targeted technical solution to solve the inevitable dust with limited size by encapsulating key system components and guiding them through with the best heat exchange with the system components to be cooled without being hindered as much as possible.

[0009] Radial flux motors can be divided into motors with an inner rotor or motors with an outer rotor. The inner rotor has greater power potential here and is generally more suitable for the requirements of power tools.

[0010] A permanent magnet excited synchronous motor with a stator ring winding is known from US 4,547,713, which is implemented as a pure ring without forming slots or teeth. Thus, the width of the magnetic air gap between the rotor and the stator is adversely affected by the winding itself, because the air gap must be at least as wide as the winding constructed on the rotor-facing side of the stator.

[0011] US 6,924,574 also describes a ring-wound radial flux motor, which not only has an inner rotor but also an outer rotor. For this purpose, the stator ring has teeth both inwards and outwards, whereby the magnetic air gap can be kept narrow on the one hand and a larger area can be opened up on the other hand. The disadvantage is that the stator winding in the gap between its two rotors can only be cooled with difficulty, and due to the rotors moving in all directions, the dust protection of the magnetic air gap is also designed complicatedly.

[0012] A switched reluctance motor is known from US2014 / 0125155, which allows two anti-phase stator fields (each stator field having a 180° pitch) to rotate synchronously with a large number of coils and commutation devices. The rotor aligns according to its reluctance, and the system forms a rotating electromagnet, the torque of which is constant and the rotational speed can be adjusted by the turnover speed of the two stator fields.

[0013] The stator is distinguished between a stator with concentrated windings and a stator with distributed windings. Associated with electronic control, a variety of design variants are produced, which of course also have an impact on costs and production technology. Due to easy manufacturability, concentrated windings are the standard in power tools.

[0014] The present invention mainly relates to the stator and its windings. A classical stator consists of teeth (pole shoes) and the spaces between their teeth (i.e., slots). The windings are applied to the teeth in a classical manner. For high efficiency, many ampere-turns are required here (high turns in the case of as thick a wire as possible). Accordingly, the slots must be filled with copper as optimally as possible. The so-called slot fill factor is also evaluated for estimating the efficiency. At the same time, the maximum losses under load are in the copper itself, so it should also be surrounded by cooling air as optimally as possible. These two requirements are contradictory, because there can only be either a lot of copper or a large cross-section for cooling in the slot.

[0015] However, the pin winding machine for concentrated windings can neither achieve a high slot fill factor nor leave a large cross-section for penetration ventilation (due to the limited wire tension and the windings constructed thereby). The optimization of the geometric parameters is also in conflict between the largest possible air gap diameter and a high slot fill factor, since a high ampere-turn number usually requires a large amount of radial installation space, and with a constant rotor radius, the cross-section of the air gap for ventilation decreases.

[0016] In the case of a single-tooth winding, windings can be manufactured that are precisely and closely adjacent to each other, and thus a high slot fill factor can be achieved. However, the competition between a high slot fill factor and a large cross-section for penetration ventilation still exists. Summary of the Invention

[0017] Therefore, the object of the present invention is to provide an electric motor with improved winding cooling.

[0018] This object is solved by the electric motor according to claim 1 and the method for manufacturing the same according to claim 15. Preferred embodiments of the present invention are the subject matter of the dependent claims and are furthermore derived from the further description of the present invention.

[0019] The present invention particularly relates to an electric motor having an EC motor, the electric motor having:

[0020] A stator having a magnetic circuit ring concentrically surrounding an axial direction A, the magnetic circuit ring having a plurality of pole shoes at a first side extending concentrically, the pole shoes delimiting a concentrically extending, cylindrical or hollow cylindrical rotor receiving space,

[0021] A rotor arranged concentrically with the stator in the rotor receiving space,

[0022] A coolant flow space extending axially along a second side of the circuit ring opposite to the first side; and

[0023] Wherein the stator has a plurality of windings having conductor wires, the windings being wound around an axially extending segment section of the circuit ring and the windings being adjacent to the coolant flow space.

[0024] The electric motor according to the present invention has the following advantages: The stator windings are at least partially directly arranged in the cooling air flow of the coolant flow space. In this way, the windings are effectively cooled. The air gap between the rotor and the stator can be effectively prevented from dust entry by sealing devices (especially covers arranged at the axial ends of the stator and the rotor). By the present invention, the conflict between the slot fill factor and the cooling air flow existing in the prior art due to the tooth winding is eliminated.

[0025] Furthermore, it is advantageous that, compared to a machine with a classical tooth winding, the diameter of the cylindrical circumferential magnetic air gap measured about the center point M given by the axis A can be increased, since the teeth are only necessary for conducting the magnetic flux, but not for the setting of the winding or as a cooling intermediate space.

[0026] Another advantage that has been determined is that the rotor can be increased in diameter with respect to its property as a mechanical energy storage and thereby improve its power capacity. The energy storage supports the dynamic power output during load peaks. The energy stored as rotational momentum in the rotor can be immediately tapped at the output of the machine. On the other hand, an electrical energy storage must be called only via a controller (e.g., software) and converted (delayed) by an electromagnetic system. In addition, they must be implemented as a multiple (1 / efficiency) of the electromagnetic conversion of the mechanical energy storage. The power capacity of many types of power tools is based on the mechanical energy storage in the rotating components.

[0027] According to the first embodiment to be protected, an air gap is constructed between the pole shoe and the rotor, which air gap is in particular cylindrical circumferential and in particular extends concentrically with respect to the axis A. The electric machine of this embodiment has at least one sealing device for sealing the air gap.

[0028] In addition to the first embodiment to be protected, in other embodiments of the electric machine according to the invention it is preferably also provided that an air gap is constructed between the pole shoe and the rotor. Preferably, such an electric machine has at least one sealing device for sealing the air gap.

[0029] The sealing device is preferably at least one covering element, which is arranged at the axially oriented ends of the stator and the rotor, in particular at both ends. The covering element can comprise at least one cover element. In the case where the electric machine is constructed as an inner rotor, the covering element extends in the radial direction between the axis (A) and the second side of the circuit ring and preferably does not engage into the coolant flow space. In the case where the electric machine is constructed as an outer rotor, the covering element extends in the radial direction between the second side of the circuit ring and the outer side of the rotor, and preferably does not engage into the coolant flow space arranged inside the stator.

[0030] According to the second embodiment to be protected of the electric machine according to the invention, the winding extends into the coolant flow space and is spaced apart from the second side of the circuit ring in the radial direction.

[0031] By means of this arrangement it is achieved that the winding itself can be cooled more effectively by the flowing air stream, which enables a more effective dissipation of the heat losses generated in the winding. At the same time, the lossy iron of the circuit ring (i.e., the yoke) also benefits from the improved cooling, since due to the spatial separation between the winding and the second side of the yoke, the air stream can circulate unhindered and conduct the heat away from the yoke.

[0032] Such structural measures ensure that not only the windings but also the circuit loops have optimized air cooling. The distance between the outer edge of the circuit loop at the second side and the windings allows an air flow to flow around the circuit loop and carry away the heat generated in the iron-containing material there.

[0033] It is proposed that the distance measured in the radial direction between the second side of the yoke and the windings should be at least 0.5 mm, preferably between 1 mm and 2 mm or between 1 mm and 5 mm, in order to ensure sufficient air flow and thus optimal cooling. Such a distance ensures that the cooling generated by the air flow is evenly distributed, and both the windings and the circuit loops benefit from improved heat dissipation.

[0034] Preferably, in the second embodiment claimed, the windings are designed in the outer region, i.e., in the radially outward direction along the second yoke side, such that they are spread out or fan-shaped, whereby a defined distance appears between the individual winding wires. This distance is preferably at least 0.5 mm or greater, especially between 0.5 mm and 5.0 mm, which significantly improves the thermal properties of the windings. By spreading out the windings, an increased surface is created along which the flowing air stream can flow. This enlarged surface enables more efficient heat dissipation, since the air stream can better extract the heat generated from the winding wires.

[0035] By spreading out, it is ensured that the air stream can penetrate deeper into the windings and thus achieve stronger cooling. The distance between the winding wires furthermore results in the wires being positioned at an angle to each other in the radial direction. This not only causes the air stream to be better distributed over the entire winding, but also causes uniform cooling of the wires. The radial angle at which the winding wires are relative to each other furthermore contributes to the fact that the heat development is not concentrated at individual locations but is evenly distributed.

[0036] In the preferred case where the electric machine is constructed as an inner rotor, a coolant flow space is preferably constructed between the jacket (especially the housing) of the electric machine and the second side of the circuit loop.

[0037] The housing can in particular be the housing or a housing section of a device or a power tool containing the electric machine.

[0038] The electric machine is preferably constructed as an outer rotor, wherein the coolant flow space is preferably constructed in the cylindrical cavity of the stator.

[0039] Preferably, the circuit loop has at least two pole shoes that enter the circuit loop at two spaced-apart locations along the circumferential direction of the circuit loop. The section of the circuit loop arranged between these locations (referred to as the segment region) in particular has windings with conductor wires. In particular, the cross-section of this conductor wire can have various shapes, such as circular, flat or rectangular, or a combination of these shapes.

[0040] In particular, the circuit ring has a number N of pole shoes and a number N of segment regions. The circuit ring preferably has at least N pole shoes which enter the circuit ring at correspondingly spaced-apart locations in the circumferential direction, wherein the section of the circuit ring arranged between two adjacent locations has a segment region which in particular carries a winding. The pole shoes are in particular integrally connected to the circuit ring. Preferably 3 ≤ N ≤ 24. The number N is preferably an integer multiple of 3, so in particular N = M * 3, where M ≥ 1.

[0041] The winding extends in particular annularly around the segment region, such that the inner side of the circuit ring in the radial direction (i.e., the first side of the circuit ring in the case of an inner rotor; but the second side in the case of an outer rotor) and the outer side in the radial direction (i.e., the second side of the circuit ring in the case of an inner rotor; but the first side in the case of an outer rotor) are covered by the winding.

[0042] The stator preferably has an axially extending cavity, in particular a number N of cavities, wherein the cavity is delimited by a segment region of the circuit ring, two adjacent pole shoes and at least one column circumferential surface section. The column circumferential surface section is in particular arranged at the radial end of the pole shoe and is arranged parallel to the rotor in the axial direction and is in particular part of the pole shoe. In particular, an air gap exists between the column circumferential surface section and the rotor. This air gap is kept as small as possible in order to minimize the magnetic resistance. The column circumferential surface section may have an axially extending recess or opening. These cavities correspond to the slots provided between the teeth in a classical stator with a toothed winding, where they are also referred to as inter-tooth spaces. However, since half of the winding is arranged outside the slot in the case of a yoke winding, the cavities can in particular be formed smaller in the radial direction compared to the case of a classical stator with a toothed winding. Thereby, the diameter of the rotor can be increased with almost the same structural dimensions and thus the power can be increased.

[0043] The teeth preferably do not carry a winding. However, a winding can additionally be provided on at least one tooth, a plurality of teeth or all teeth.

[0044] Independently of the fact that the slots or inter-tooth spaces can be very small in the winding and control concept of the EC motor according to the invention, it is feasible that one or more of these slots or these inter-tooth spaces have devices for detecting measured values, in particular data, such as rotor position, temperature, etc. Here, these devices can for example comprise one or more sensors, in particular Hall sensors, windings, etc. The control device is preferably set or programmed to detect at least one measured value of at least one device for detecting measured values and in particular to use it to control the motor.

[0045] The circuit loop is preferably composed of several individual segment sections. The segment sections preferably contain a plurality of segment regions, or in particular a two-segment region or a three-segment region having two or three segment regions. The structure of the circuit loop composed of a plurality of segment sections provides the advantages of a more compact and generally simpler winding of the circuit loop and thus more economical production. The individual segment regions can preferably be form-fittingly connected.

[0046] The circuit loop preferably has a plurality of individual segment sections, wherein each segment section can have one, two, three or more segment sections. Each segment section can have at least one or exactly one pole shoe, which can in particular be integrally connected to the segment section. In particular, the circuit loop can have at least one connecting section, which is in particular used to connect two adjacent segment sections in the circumferential direction. The connecting section can in particular be form-fittingly connected to at least one or two segment sections.

[0047] In this regard, the circuit loop can be formed by a plurality of individual components. At least one of these components, in particular the connecting section, can have at least one fixing device for fixing the connection of these components, in particular the connection of two adjacent components, such as the connection of two connecting sections or the connection of a connecting section and two segment sections. The connecting device can have at least one (in particular exactly one) pole shoe of the circuit loop.

[0048] The fixing device can in particular contain a slit in at least one connecting section, which is in particular introduced into the connecting section from the outside to the inside in the radial direction. Preferably, at least one wedge element is provided, which is form-fittingly introduced into the slit in the engaged position in order to generate a tension in the circumferential direction, by means of which the plurality of components of the circuit loop are caulked. Alternatively, the fixing device can contain at least one pin element, in particular a threaded part, by means of which adjacent, in particular screwable, components are fixed.

[0049] The at least one wedge element can extend in the axial direction over the entire axial length of the circuit loop or only over a partial section of the length of the circuit loop.

[0050] The wedge element can have a locking device by means of which the wedge element is fixed in the engaged position to prevent the wedge element from undesirably exiting in the radial direction. The locking device can be a protrusion of the wedge element, which engages into a receiving part of the connecting section in the engaged position. Correspondingly, the locking device can be a receiving part of the wedge element, into which a protrusion of the connecting section engages in the engaged position.

[0051] Preferably, the arrangement consisting of the rotor and the stator has a maximum radius R; the stator preferably has a maximum extension L in the radial direction, where preferably, L ≤ f*R, where preferably, 0.1 ≤ f ≤ 0.5, preferably 0.2 ≤ f ≤ 0.45. In the case of an inner rotor, the maximum extension L of the stator in the radial direction is in particular less than 0.5 times the radius R of the rotor. Thereby, the rotor can be made more massive in order to improve its properties as an energy storage.

[0052] The pole shoes preferably have no windings. Thereby, in particular, their radial extension can be minimized.

[0053] Preferably, in the case of an inner rotor, the rotor is only arranged inside the stator and not outside the stator.

[0054] Preferably, in the case of an outer rotor, the rotor is only arranged outside the stator and not inside the stator.

[0055] The electric machine is preferably constructed as an electric motor, in particular an EC motor, in particular as a permanently magnetically excited synchronous motor.

[0056] The electric machine is preferably constructed as an inner rotor.

[0057] The electric machine is preferably constructed as an outer rotor.

[0058] The invention also relates to a power tool having an electric machine according to the invention, in particular a hand-held power tool, in particular a angle grinder or a drill.

[0059] The invention also relates to a method for manufacturing an electric machine according to the invention, having the following steps:

[0060] * Providing a stator having a loop ring and a plurality of pole shoes,

[0061] * Winding the loop ring with conductor wire, in particular with a number N of windings,

[0062] * Arranging the stator coaxially with the rotor,

[0063] * Providing a coolant flow space adjacent to the second side of the loop ring,

[0064] * Preferably: Sealing the air gap between the stator and the rotor with at least one sealing device.

[0065] In this method, it is in particular provided that a loop ring consisting of a plurality of individual segment sections is provided. Here, it is preferred that the segment sections are first wound before being assembled, in particular joined together, to form the loop ring or the stator. This manufacturing or winding method can be carried out particularly economically. Description of the Drawings

[0066] Further advantages, features and possible applications of the invention result from the following description in conjunction with the drawings:

[0067] Figure 1a A schematic front view of an EC motor according to the prior art is shown.

[0068] Figure 1b A perspective view of an EC motor according to the prior art is shown.

[0069] Figure 2a A schematic front view of an EC motor according to the prior art is shown.

[0070] Figure 2b A schematic front view of an EC motor according to the invention according to an embodiment is shown.

[0071] Figure 2c A schematic front view of an EC motor according to the invention according to an embodiment is shown.

[0072] Figure 3a A schematic front view of an EC motor designed as an outer rotor according to the prior art is shown.

[0073] Figure 3b A schematic front view of an EC motor designed as an outer rotor according to the invention according to an embodiment is shown.

[0074] Figure 4 In comparison with Figure 2c A schematic front view of an EC motor according to the invention is shown, without windings.

[0075] Figure 5 Shows Figure 4 The perspective arrangement of a segment section of the yoke of an EC motor, with windings.

[0076] Figure 6 A comparison of the electromagnetic effects between an EC motor with tooth windings according to the prior art and an EC motor with yoke windings according to the invention is shown, with their phases energized differently.

[0077] Figure 7 A perspective view of an EC motor according to the invention according to an embodiment is shown, with the housing open.

[0078] Figure 8 Shows a cross-section through Figure 7 the axial cross-section of an EC motor.

[0079] Figure 9 A cross-section through the axial cross-section of an EC motor with an axial seal is shown.

[0080] Figure 10Shows an axial cross-section of an EC motor having windings spaced apart on the second yoke side.

[0081] Figure 11 Shows Figure 10 a radial cross-section of the EC motor of Detailed Description

[0082] Figure 1a Shows a schematic front view of an EC motor according to the prior art. The EC motor is implemented as an inner rotor: a rotor 20 rotating about an axis rotates within a stator 10 with a drive shaft (not shown). The stator 10 has teeth 11 made of a material with high magnetic permeability, such as iron, which serve as pole shoes and are connected via an external loop ring 15 (also called a yoke 15). Slots 12 are formed between the teeth 11, which have slot openings 13 constructed between adjacent tooth heads 14 in the direction of the rotor 20.

[0083] Each tooth has a winding 16 with copper wire. The connection of the windings corresponds to a three-phase system. Here, two radially opposite windings are associated with one phase each, since it is a motor with two pole pairs and thus 6 teeth / slots. In the case of a three-phase motor, an arrangement with a multiple of the number of windings (here: teeth) corresponding to three is in principle possible. In Figure 1a one of the six teeth is not shown for better identification of the tooth geometry.

[0084] When the three phases are energized with three-phase current, a rotating magnetic field is constructed at the motor. Its field lines are basically in the iron circuit consisting of the teeth 11, the loop ring (yoke 15) and the rotor 20. The field lines also extend through the magnetic air gap 30 constructed between the rotor and the tooth head, and it is constructed as narrow as possible for a small magnetic resistance. Since the field lines pass through the air gap in the radial direction, it is also called a radial flux motor.

[0085] The rotor has four permanent magnets 21, which have different pole polarities, where two magnets with the same pole polarity are radially opposite each other in pairs.

[0086] In Figure 2a again shows a known EC motor according to Figure 1a which has three phases u, v, w, each of which is formed by two radially opposite teeth.

[0087] Figure 2b Shows a schematic front view of an EC motor 100 according to the invention according to an embodiment. The rotor 120 is the same as the rotor 20. The stator 110 is the same as the stator 10 except for the windings 16 / 116. Instead of as in Figure 2aWindings arranged around the teeth as in [reference], where winding 116 is guided around yoke 115 here, more precisely around segment section 117 placed between coupling parts of adjacent teeth 118. Thus, the winding can be called toroidal, as is the case with toroidal core coils.

[0088] In addition, in Figure 2b the copper windings are not applied to the teeth in multiple layers as in, for example, Figure 2a but are applied to the circuit loop (yoke) in fewer layers ( Figure 2b , 2c ).

[0089] Figure 2c Only a truncated view of the coolant flow space 150 of the motor is shown in [reference]. In reality, the coolant flow space extends cylindrically as a cavity between the second side 152 of the circuit loop and the jacket of the stator, such as the jacket of the motor housing (not shown). The coolant flow space 150 extends in the axial direction along the second side 152 of the circuit loop, which is opposite to the first side 151 of the circuit loop. Here, the first side 151 of the circuit loop points radially inwards and the second side 152 points radially outwards. The windings 116 are wound around the axially extending segment areas of the segment sections 117 of the circuit loop and enter the coolant flow space 150. Thus, the windings are effectively and directly cooled by the coolant (here air) flowing in the axial direction in the coolant flow space.

[0090] Figure 2c Shows an arrangement that is basically corresponding to Figure 2b where the space within yoke 115 obtained by transferring the windings from the teeth is used to increase the diameter D of rotor 120 and minimize the radial length of teeth 118. In addition, the slot openings are omitted and the teeth 118 are connected radially internally, resulting in a radially enclosed bushing 119 for the motor.

[0091] The possible increase in the outer diameter of the rotor also provides the possibility of equally increasing the inner diameter of the rotor or the outer diameter of the shaft (not shown) connected to the rotor. Thus, the stability of the shaft can be increased. Additionally, the increase in the inner diameter of the rotor provides the possibility of using an insulated or coated drive shaft.

[0092] Many parameters are positively affected by the arrangement according to the invention.

[0093] In most cases, a circuit ring 115 located at the outer circumference of the motor only guides all magnetic fluxes that are regarded as necessary magnetism, and according to the present invention, it becomes the location of the winding 116. Thus, the teeth 118 can become smaller in the radial direction, and thus the distance between the magnetic air gap 130 and the axis center point M can be increased, and therefore the diameter D of the air gap 130 can be selected to be larger. The arrangement composed of the rotor and the stator has a maximum radius R, and the rotor has a maximum diameter D, where approximately D = 1.4 * R. Therefore, in Figure 2c the rotor 120 is designed to be particularly massive.

[0094] Since the winding of the circuit ring 115 according to the present invention is a toroidal winding 116, the stator can be formed by segments or segment sections, and these segment sections 117 can be wound individually independently of each other. For example, Figure 4 shows a stator 110 having 3 segment sections 117. Thus, precise and economical individual segment winding of each segment section 117 can be achieved.

[0095] Figure 3a shows a schematic front view of an EC motor designed as an outer rotor according to the prior art, which has a tooth winding.

[0096] Figure 3b shows a schematic front view of an EC motor 400 according to the present invention designed as an outer rotor according to an embodiment. The electric motor 400 has a stator 410, and a rotor (outer rotor) 420 rotates around the stator 410 in an external circumferential manner. The internally placed stator has an axially concentrically surrounded circuit ring 415 (yoke 415; more precisely: circuit hollow cylinder 415), and teeth 418 of the circuit ring 415 extend radially outward from the circuit ring 415. The winding 416 is also wound around the segment sections 417 of the yoke 415 here, and the teeth are also shortened and not wound here.

[0097] Figure 3b also shows a coolant flow space 450 of the motor. The coolant flow space 450 extends in the axial direction along a second side 452 of the circuit ring, and this second side is opposite to a first side 451 of the circuit ring. Here, the first side 451 of the circuit ring points radially outward, and the second side 452 points radially inward. The winding 416 is wound around the axially extending segment sections 417 of the circuit ring respectively and reaches into the coolant flow space 450. Thus, the winding is effectively and directly cooled by the coolant (here air) flowing in the coolant flow space in the axial direction.

[0098] Figure 4 shows a top view of a so-called sheet segment. The stator or the rotor is formed by a large number of individual sheets to limit the adverse effects of eddy currents.

[0099] Figure 4 As shown, in the case of an even number of teeth / slots, single-tooth winding can also be advantageously implemented by winding the double-segment section 122. This double-segment section 122 is a segment section having two segment regions respectively provided for winding. Figure 4 The unwound stator 110 shown has a yoke 115 composed of three double-segment sections 122. The double-segment sections 122 are respectively centered on the radially outer contact portions 123 of the teeth 118 and are connected to the adjacent teeth 118 at the connection portions 124 at their ends. All the teeth 118 are preferably formed together by a firm internal sheet metal cutout. In the case of an odd number of teeth / slots, single-tooth winding can be achieved in a similar manner by a three-segment section.

[0100] In Figure 5 an example of the wound double-segment section 122 can be seen. With a 2-layer winding 116, more ampere-turns can be achieved than in the case of a 4-layer tooth winding 16 ( Figure 3a ), thereby enabling better cooling of the (multiple) internal copper layers as well.

[0101] The fixed part of the sheet metal cutout 118 not only ensures the concentric arrangement of the individual teeth in the case of a centering bearing end cover but also ensures a seamless seal of the magnetic air gap. It also reduces the cogging torque of the EC motor.

[0102] The larger rotor 120 due to the increased air gap diameter enables mechanical energy storage increasing with the square of the diameter D to be used for smoothing the rotational speed at load peaks and due to control gaps in, for example, network machines with a slender intermediate circuit (AC ripple). If a short braking time is standard, the rotor can of course also be implemented with a lower moment of inertia by a larger plastic core or by openings in the sheet metal cutout.

[0103] The larger air gap diameter D also results in a higher torque constant. It is mostly given in mNm / A in its preferred power class here and has an impact on the continuous power and efficiency of the motor.

[0104] Figure 6 shows the electromagnetic effect generated by the conventionally wound stator 10 ( Figure 2a ) when it is energized alternately in two phases. In parallel, it shows how the stator 110 according to the invention must be energized to achieve the same electromagnetic effect: This is shown based on the magnetic flux generated related to the position of the rotating permanent magnet. It has been found that for the same electromagnetic effect, the control of the motor phase should be changed according to Figure 6 .

[0105] To completely seal the magnetic air gap, as a preferred design feature, it is arranged that the bearing end cover of the motor or the end cover without ball bearings is connected to the fixed part of the stator plate cut-out in such a way that the opening on the end side of the magnetic air gap is closed, as can be seen from the comparison with Figure 2c in Figure 2b . From this and due to the missing slot opening 114, dust cannot penetrate into the magnetic air gap and adhere to it.

[0106] At the same time, the bearing end cover can be centered relative to the air gap. For self-supporting motors, it can be used on both bearing sides.

[0107] Figure 7 and Figure 8 show an EC motor 300 according to the invention, which has a stator 310 with a winding 316 around the yoke, the winding 316 being wound around a segment section while the teeth 318 are not wound. The motor electronics 340 extends axially from the interior space of the motor housing 339 into the handle area 341.

[0108] The motor 300 has a rotor 320 with a drive shaft 331 fastened therein.

[0109] For the drive 300, only the rear bearing 332 (B side) is centered at the stator, and on the A side, the shaft 331 is accommodated via a ball bearing 333 in a drive mechanism head (not shown) centered relative to the motor housing 339. Thereby, centering relative to the air gap is also achieved there, and the stator 310 is correspondingly accommodated and centered by the tool housing 339.

[0110] The cover element 335 arranged at the end of the stator / rotor or the motor and the cover element or bearing end cover 336 arranged at the other end form a sealing device and seal the motor area located within the yoke 315 in the axial direction in such a way that dust cannot reach this motor area. At the same time, the second side 352 of the yoke 315 and the winding 316 are directly located in the air-cooled coolant flow space 350, here the intermediate space 350 between the motor and the motor housing, in which the air flow generated by the fan 334 has an optimal cooling effect in the axial direction.

[0111] An advantageous type of interconnecting the motor windings is to use cut-clamp contacts (Schneid-Klemm-Kontakten), which are themselves connected to one of four interconnect types via a printed circuit board (for a three-phase system: star or delta and series or parallel).

[0112] Known BLDC motors (EC motors) have a stator outer diameter of 48 mm. However, fully encapsulated motors (in which the stator is also fully encapsulated) are constructed with bearing end caps made of die-cast aluminum, which is also a key cost factor. Here, the maximum outer diameter reaches 58 mm. For the present invention, this diameter difference can be used for larger motors with greater power or for removing dust or for smaller gripping dimensions.

[0113] Figure 9 An axial seal of the entire internal space including the magnetic air gap is drafted. The seal of the magnetic air gap here should meet two requirements: First, as much of the copper winding 116 as possible should be in contact with the coolant to ensure optimal heat dissipation. Second, the magnetic air gap should be hermetically sealed to ensure the functionality of the system.

[0114] For the winding 116(1) at the yoke 115, the two requirements are met by the sealing profile shown by the outer one of the two dash-dotted lines. At least half of the winding 116(1) is arranged in the cooling air flow here, and the seal can be completely formed as a cover placed axially on the motor, that is, it can be placed on the end side of the motor in a basically flat and two-dimensional manner. This structural method ensures high manufacturing precision because the winding 116(1) is only slightly coated at the axial winding head.

[0115] In contrast, in the unloaded toothed winding 116(2), a suitable sealing profile can only be achieved with a considerable amount of effort. The seal shown by the inner one of the two dash-dotted lines is only achieved by a combination of axial and three-dimensional sealing measures. Only in this way can it be achieved that not only a considerable part of the copper winding 116(2) is in contact with the coolant but also the magnetic air gap remains completely sealed.

[0116] Figure 10 An axial section of an EC motor according to the second embodiment to be protected is shown, which has preferably multi-piece loop rings and windings 116 extending into the coolant flow space 150. In the illustrated embodiment, the loop rings each include three substantially identical components 115(1) and 115(2), which are arranged alternately to form the loop rings. The components of the group 115(2) (also respectively called the connecting sections of the loop rings) additionally each have a slit at their radially outer ends, so that a wedge (not shown) can be introduced into this slit to caulk the stator. In this way, the already form-fitting connection of the adjacent components of the loop ring is further fixed.

[0117] In addition, Figure 10 It is shown that the winding 116 extends into the coolant flow space 150 and is radially spaced from the second side 152 of the loop rings 115(1) and 115(2).

[0118] Due to this arrangement, a more efficient cooling of the winding 116 is achieved by the air flow passing through the coolant flow space 150, which results in a better thermal dissipation of the losses generated in the winding 116. At the same time, the lossy iron of the loop also benefits from the optimized cooling because, due to the spatial separation between the winding 116 and the loop, the air flow can circulate unobstructed and thus dissipate heat from the loop.

[0119] This construction ensures that not only the winding 116 but also the loop benefits from the improved air cooling. The distance between the outer edge of the loop at the second side 152 and the winding 116 enables the air flow in the coolant flow space 150 to flow around the loop and dissipate the heat generated in the iron of the loop there.

[0120] In the illustrated embodiment, the windings 116 are designed in the outer region such that they are unfolded or fan-shaped, thereby creating a defined distance between the individual winding wires. By unfolding the windings 116, a larger surface is created along which the passing air flow can flow. This increased surface enables more efficient heat dissipation because the air flow can better extract the generated heat from the winding wires.

[0121] This unfolding furthermore ensures that the air flow in the coolant flow space 150 can penetrate deeper into the windings 116 and thus achieves stronger cooling. The distance between the winding wires furthermore causes the wires to be arranged at an angle to one another in the radial direction. This not only results in a better distribution of the air flow in the coolant flow space 150 over the entire winding 116 but also in a uniform cooling of the wires. The radial angle of the winding wires 116 contributes to the fact that the heat development is evenly distributed and does not concentrate at individual locations.

[0122] Figure 11 is shown Figure 10 an embodiment in which the distance between the winding 116 and the second side of the loop 115 is 1 mm here. This ensures a sufficient air throughput and thus optimal cooling. Such a distance also ensures an even distribution of the cooling, and both the winding 116 and the loop 115 benefit from the improved heat removal.

[0123] List of reference numerals:

[0124] 10 Stator

[0125] 11 Teeth

[0126] 12 Slots

[0127] 13 Slot openings

[0128] 15 Yoke, loop

[0129] 16 Windings

[0130] 20 Rotor

[0131] 21 Permanent Magnet

[0132] 30 Air Gap

[0133] 100, 200, 300, 400 Motors

[0134] 110, 210, 310, 410 Stators

[0135] 130 Air Gap

[0136] 114 Slot Mouths

[0137] 115, 215, 315, 415 Yokes, Loop Rings

[0138] 116, 216, 316, 416 Windings

[0139] 117, 417 Sections

[0140] 118, 218, 318, 418 Teeth, Pole Shoes

[0141] 119 Bushing

[0142] 120, 320 Rotors

[0143] 122 Double Section

[0144] 123 Contact Part

[0145] 124 Connection Part

[0146] 150, 350, 450 Coolant Flow Spaces

[0147] 151, 351, 451 First Side of Loop Ring

[0148] 152, 352, 452 Second Side of Loop Ring

[0149] 331 Drive Shaft

[0150] 332 Bearing

[0151] 333 Ball Bearing

[0152] 334 Fan

[0153] 335, 336 Cover Elements, Bearing End Covers

[0154] 339 Motor Housing

[0155] 340 Control Electronics

[0156] 341 Handle area

[0157] 420 Rotor, outer rotor

[0158] D Air gap diameter

[0159] Center point of M 331

[0160] R Stator radius

[0161] A Stator thickness.

Claims

1. An electric machine, in particular an EC motor, having a stator (110; 210; 310; 410) with a magnetic circuit ring (115; 215; 315; 415) concentrically surrounding an axial direction A, the magnetic circuit ring having a plurality of pole shoes (118; 218; 318; 418) at a first side (151; 351; 451) extending concentrically, the pole shoes delimiting a concentrically extending, cylindrical or hollow cylindrical rotor receiving space, a rotor (120, 320) arranged concentrically with the stator in the rotor receiving space, the electric machine having a coolant flow space (150; 350; 450) extending axially along a second side (152; 352; 452) of the circuit ring opposite to the first side (151; 351; 451); and the stator (110; 210; 310; 410) having a plurality of windings (116; 216; 316; 416) with conductor wires, the windings being wound around axially extending segment sections (117; 417) of the circuit ring (115; 215; 315; 415) respectively and the windings being adjacent to the coolant flow space (150; 350; 450), characterized in that an air gap (130) is formed between the pole shoes (118; 218; 318; 418) and the rotor (120, 320), and wherein the electric machine has at least one sealing device (335, 336) for sealing the air gap.

2. An electric machine having an EC motor, the electric machine having: a stator (110; 210; 310; 410) with a magnetic circuit ring (115; 215; 315; 415) concentrically surrounding an axial direction A, the magnetic circuit ring having a plurality of pole shoes (118; 218; 318; 418) at a first side (151; 351; 451) extending concentrically, the pole shoes delimiting a concentrically extending, cylindrical or hollow cylindrical rotor receiving space, a rotor (120, 320) arranged concentrically with the stator in the rotor receiving space, the electric machine having a coolant flow space (150; 350; 450) extending axially along a second side (152; 352; 452) of the circuit ring opposite to the first side (151; 351; 451); and the stator (110; 210; 310; 410) having a plurality of windings (116; 216; 316; 416) with conductor wires, the windings being wound around axially extending segment sections (117; 417) of the circuit ring (115; 215; 315; 415) respectively and the windings being adjacent to the coolant flow space (150; 350; 450); characterized in that The winding (116; 216; 316; 416) extends into the coolant flow space (150; 350; 450) and is radially spaced from the second side (152; 352; 452) of the circuit ring.

3. The motor according to claim 2, wherein The winding (116; 216; 316; 416) is spread out so that there is a distance between the individual winding wires.

4. The electric machine according to any one of claims 1 to 3, wherein, The rotor includes at least one or more permanent magnets.

5. The electric machine according to any one of claims 1 to 4, wherein the electric machine is configured as an inner rotor, The coolant flow space is configured between the jacket of the electric machine, in particular the housing (339), and the second side of the circuit ring.

6. The electric machine according to any one of claims 1 to 4, wherein the electric machine is configured as an outer rotor, The coolant flow space is configured in the cylindrical cavity of the stator.

7. The electric machine according to any one of the preceding claims, wherein, The circuit ring has at least two pole shoes that enter the circuit ring at two spaced-apart locations along the circumferential direction of the circuit ring, wherein the section of the circuit ring arranged between these locations has this segment area.

8. The electric machine according to any one of the preceding claims, wherein, The circuit ring consists of a plurality of individual segment sections (117, 417).

9. The motor according to claim 8, wherein, The segment section includes a plurality of segment areas, in particular in such a way that a double segment section (122) has two segment areas, and a winding is arranged around each segment area.

10. The electric machine according to any one of the preceding claims, wherein, The arrangement consisting of the rotor and the stator has a maximum radius R, and wherein the stator has a maximum extension L in the radial direction, where L ≤ f * R, and preferably 0.1 ≤ f ≤ 0.5, preferably 0.2 ≤ f ≤ 0.

45.

11. The electric machine according to any one of the preceding claims, wherein, The pole shoes do not have windings.

12. The electric machine according to any one of the preceding claims, wherein the electric machine is configured as an electric motor, in particular an EC motor, in particular as a permanent magnet excited synchronous motor.

13. The electric machine according to any one of claims 1 to 12, wherein the electric machine is configured as an inner rotor.

14. The electric machine according to any one of claims 1 to 12, wherein the electric machine is configured as an outer rotor.

15. A method for manufacturing an electric machine according to any one of claims 1 to 14, having the following steps: * providing the stator, which has a circuit ring and a plurality of pole shoes, * winding the circuit ring with conductor wires, * arranging the stator coaxially with the rotor, * providing the coolant flow space adjacent to the second side of the circuit ring.

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