Electric machine

Abstract

The invention relates to an electric machine

Description

The invention relates to an electrical machine according to the preamble of claim 1. Electric machines are used to convert electrical energy into mechanical energy or vice versa. An electric machine designed as a drive machine for a motor vehicle is particularly suitable for use within the powertrain of a hybrid or fully electric vehicle. The stator, and potentially also the rotor, of such an electric machine consists of a cylindrical, magnetically flux-carrying base body in which a multitude of circumferentially distributed slots are provided for receiving the electrical conductors of the coil. The slot openings, which form radially around the base body and alternate with tooth-like areas created by these slots, are often closed by appropriately dimensioned slot closures. These closures have a length, a width, and a thickness. The length is essentially determined by the axial length of the cylindrical base body, and the width is essentially determined by the circumferential width of the slot opening. Furthermore, the width and thickness are such that the closure can be inserted into the slot opening and fixed within it. It is generally known to fill cracks, cavities, or gaps within the grooves between the electrical conductors and the side walls of the base body with a curable filler, usually resin-based. It is also known to use the so-called trickle method for this purpose, in which, for example, liquid resin is trickled onto an axial end face of the assembly consisting of the base body and coil assembly, such as from a winding head. This resin is then drawn axially into the respective groove by gravity and capillary action, where it subsequently hardens. However, such trickle methods via the winding head side are relatively complex to implement, as the resin requires a considerable amount of time to fill the groove along its entire axial length. Furthermore, there is the disadvantage that any excess filler residue on the axial end faces must be laboriously removed from the winding heads. From DE 10 2020 215 736 A1, it is known that a slot filling device is arranged to fill cavities in the rotor of an electric machine with pronounced cylindrical slots in the respective slots, wherein the slot filling element has a channel for the flow of a curable filler, and the channel has an inlet and at least one outlet, and wherein the outlet is arranged at the windings. However, due to the pronounced cylindrical slot shape, the channel shapes in the slot filling device disclosed here are very complex. In an application filed by the applicant under file number 10 2023 131 891.8 on September 8, 2023, an electric machine and a trickle impregnation process are described in which a groove sealing means has at least one radial opening through which a curable filler can flow into the respective groove, if the cylindrical base body is sprinkled with the curable filler at a specific axial position on its radial side - i.e. not via the winding head sides - and if, after flowing through the at least one opening, the filler can distribute itself both radially and axially in the grooves. The object of the present invention is now to provide an electric machine in which openings for drip impregnation can be dispensed with in the groove closure means. According to the invention, this problem is solved by the electric machine with the features of claim 1. Advantageous further developments of the invention are defined in the respective dependent claims. Because the tooth-like areas between the slots of a base body, such as a stator, in an electric machine have at least one opening on at least one of their two side surfaces facing the adjacent slots, and this opening extends radially beyond the thickness of the slot closure, a curable filler can flow radially from outside the slot into the slot during manufacturing. This filler fills gaps, cavities, or spaces within the slots between the electrical conductors themselves and / or between the electrical conductors and the side walls of the base body. Openings in the slot closures themselves can thus be avoided, which does not impair their rigidity and therefore simplifies their assembly. If the opening area of ​​at least one recess has a greater extent in the axial direction of the base body than in the circumferential direction, the opening area formed by the recess can be chosen to be large enough to achieve a high-quality filling of the groove in a short dosing time. Furthermore, the smaller circumferential extent of at least one recess ensures that the required magnetic properties of the magnetic flux-carrying element, whether a stator or a rotor body, can still be maintained. The radial opening can, for example, be a recess with a round, square, oval, or any other suitable partial cross-section. This allows for a particularly flexible design of the opening, which can be selected depending on the specified parameters of the electric machine. The shape and number of recesses in the tooth-like areas are independent of the properties of the groove closure means and therefore do not affect their stiffness, because, according to the invention, the one or more recesses are located predominantly or exclusively in these tooth-like segments formed by the circumferential grooves, i.e., the stator teeth and / or, if applicable, also in the rotor teeth. If one or more recesses extend close to the bottom of the groove, the curable filler, such as a trickle resin, can penetrate more effectively to the bottom of the groove, which can have a positive effect on the processing time. This is particularly advantageous with higher viscosity trickle resins. Furthermore, it is advantageous if several recesses are provided as openings on both side surfaces of the tooth-like areas facing the respective adjacent grooves, and if these are also arranged offset from each other in the axial direction on the two side surfaces. The numerous recesses distributed around the groove closure element allow the dripping process to be further improved and optimized because the dripping resin can flow more evenly into the grooves. Ultimately, the shape and number of cutouts can be freely chosen. In principle, all shapes that can be punched into the laminations of the stator or rotor body are conceivable. The shape and radial depth of the cutout can be formed by stacking the individual, appropriately punched laminations. The invention is explained in more detail by way of example with reference to the figures. They show schematically and not to scale: Fig. 1 a stator as a magnetic flux-carrying element with base body; Fig. 2 a detail of the base body; Fig. 3 a detail of the stator base body with two slots; Fig. 4 a detail view of a slot opening. Figure 1 shows a stator as a magnetic flux-carrying element 1, which has a cylindrical base body 2 and, as can be seen more clearly in Figure 3, several grooves 3 circumferentially formed in the base body 2 with tooth-like sections 18 formed between them. In a stator, the grooves in the cylindrical base body 2 are open radially inwards. Appropriately designed and adapted groove closure elements 7 can then be inserted into these groove openings of the grooves 3 of the base body 2 in the usual manner and fastened or clamped there. Fig. 2 shows a detailed section of the base body 2 with several groove closure elements 7 in the corresponding groove openings. The opening surfaces of the openings 8 according to the invention are clearly visible in a preferred embodiment. These openings 8, formed as recesses in the base body 2, are located next to the groove closure elements 7 in the circumferential direction of the base body. Specifically, there are three elongated openings 8, uniformly spaced and extending axially in the direction of the base body 2, on one side of each groove closure element 7. A curable filler, such as a drip resin with a viscosity of up to 30 mPas, can be applied to the groove closure elements 7 from the radial inside, i.e., from the direction of the center of the cylindrical base body, using a drip lance as schematically indicated in Fig. 1. From there, it can flow through the openings 8 into the grooves. Fig. 3 shows a section of the stator, i.e., the magnetic flux-carrying element 1, with the base body 2 and two grooves 3 formed therein. Between the individual grooves 3, the tooth-like areas 18 formed by the grooves 3 can be seen in the circumferential direction of the base body 2. The grooves 3 have a groove base 10 and two lateral groove walls, which correspond to the side surfaces A1 and A2 of the tooth-like areas 18. The grooves 3 can be filled with electrical conductors 4 and closed radially at the groove openings with groove closures 7. In the case of a cylindrical base body 2, such as that of a stator consisting of a plurality of sheets stacked axially along the cylindrical base body 2, these groove openings are directed radially inwards and can thus be dripped with the filler material using the drip lance shown in Fig. 1. According to the invention, as schematically shown in Fig. 4, at least one opening 8, designed as a recess, is formed on at least one of the two side surfaces A1 of the tooth-like areas 18 facing the respective adjacent grooves 3. This opening 8 extends in the radial direction of the base body 2 beyond the thickness d of the groove closure means 7 so that the curable filler can flow into the groove in the radial direction of the base body 2 through at least one of the recesses. Reference symbol list 1 Magnetic flux-carrying element 2 Base body 3 Groove 4 Electrical conductor 5 Coil 7 Groove closure means 8 Opening 10 Groove base 18 Tooth-like area A1 First side surface of the tooth-like area A2 Second side surface of the tooth-like area QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature DE 10 2020 215 736 A1

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Claims

An electric machine with a magnetic flux-carrying element (1) and a current-carrying element, wherein the magnetic flux-carrying element (1) has a cylindrical base body (2) and several grooves (3) formed circumferentially in the base body (2) with tooth-like areas (18) formed between them, and wherein a coil (5) forming an electrical conductor (4) is positioned in the grooves (3), and wherein the grooves (3) are each closed with a groove closure means (7) having a thickness (d), characterized in that the tooth-like areas (18) have at least one opening (8) formed as a recess on at least one of their two side surfaces (A1, A2) facing the respective adjacent grooves (3), wherein the opening (8) extends in the radial direction of the base body (2) beyond the thickness (d) of the groove closure means (7) to such an extent thatthat a curable filler can flow into the groove in the radial direction of the base body (2) via at least one of the recesses. Electric machine according to claim 1, characterized in that the at least one opening (8) is a recess whose opening area has a greater extent in the axial direction of the base body (2) than in the circumferential direction. Electric machine according to one of claims 1 or 2, characterized in that the at least one opening (8) is a recess with a round, angular or oval partial cross-section. Electric machine according to one of the preceding claims, characterized in that several recesses are provided as openings (8) in the axial direction of the base body (2) evenly distributed over the axial length of the base body (2). Electric machine according to claim 4, characterized in that on both side surfaces (A1, A2) of the tooth-like areas (18) facing the respective adjacent grooves (7) several recesses are provided as openings (8) evenly distributed over the axial length, and these are arranged offset from each other in the axial direction on the two side surfaces (A1, A2). Electric machine according to one of the preceding claims, characterized in that the at least one recess extends in the radial direction of the base body to near a groove base (10) of the grooves (7).

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