DE102021119140A1 - Rotor of an externally excited electrical machine, electrical machine, motor vehicle and method for producing a rotor - Google Patents

Abstract

The invention relates to a rotor (RO) for an externally excited electrical machine (EM) of a motor vehicle (KFZ), having a plurality of laminations (BL) arranged one behind the other in the axial direction of the rotor (RO), each lamina (BL) having an annular configuration Yoke (JO) with a yoke outside (JAS) directed outwards in the radial direction of the yoke (JO), on the yoke outside (JAS) a plurality of pole shafts (PST) are arranged spaced apart from one another in the circumferential direction, on which a rotor winding (RW) can be arranged and/or arranged, each pole shaft (PST) has a pole shoe (PSH) arranged and/or fastened on a pole shaft end (PSE) aligned in the radial direction, with a gap opening (SO) between two in the circumferential direction of the rotor (RO) pole shoes (PSH) arranged next to one another via a circumferential tube (UR) and/or via a web (ST) formed between the adjacent pole shoes (PSH), at least in sections is closed in the axial direction of the rotor (RO).

Description

The invention relates to a rotor for an externally excited electrical machine, the rotor having salient poles, so-called pole teeth, with a pole shaft and a pole shoe that can be slipped onto the pole shaft. A pre-wound rotor winding is slipped onto the pole shaft. The pole shoe is then fixed to the pole shaft. The pole teeth are connected to one another at least in sections via connecting webs or via a peripheral tube. The invention also relates to an electrical machine with the rotor according to the invention. In addition, the subject matter of the invention is a motor vehicle with the electric machine. Furthermore, the subject matter of the invention is a method for producing the rotor according to the invention.

Rotors for electrical machines in motor vehicles, in particular axle drives, are known in principle. The rotors can either be permanently excited or externally excited via a winding. Due to the limited availability of rare earths for the magnets of the permanently excited rotors and the increased sales of at least partially electrically driven vehicles, the separately excited electrical machines are becoming increasingly important. One aspect of the manufacture of separately excited rotors is, among other things, the arrangement of the winding on the pole teeth of the rotors. Due to the space available between the pole teeth, this is time-consuming and costly, as a result of which the rotors can have increased manufacturing costs.

One object of the invention is to provide a rotor for an externally excited electrical machine in a motor vehicle, which rotor can be produced inexpensively and can have increased rigidity.

This object is solved by the subject matter of patent claim 1. Preferred developments of the invention are the subject matter of the dependent claims, the following description and the drawings. Each feature described and/or shown can represent an aspect of the invention both individually and in combination, unless something to the contrary is explicitly stated in the description.

According to a first aspect, the invention relates to a rotor for a separately excited electrical machine, having a plurality of laminations arranged one behind the other in the axial direction of the rotor, each laminating sheet having a ring-shaped yoke with a yoke outside directed outwards in the radial direction of the yoke, on which On the outside of the yoke, a plurality of pole shanks are arranged spaced apart from one another in the circumferential direction, on which a rotor winding can be and/or is arranged, each pole shank has a pole shoe arranged and/or fastened on a pole shank end oriented in the radial direction, with a gap opening between two in the circumferential direction of the Rotor pole shoes arranged next to one another is closed at least in sections in the axial direction of the rotor by a circumferential tube and/or by a web formed between the adjacent pole shoes.

In other words, according to the first aspect of the invention, a rotor is provided for an externally excited electrical machine. The electrical machine is preferably used in an at least partially electrically driven motor vehicle. It is preferably provided that the electric machine is arranged in a traction drive, in particular in an axle drive, of the motor vehicle.

The rotor has a plurality of laminations arranged one behind the other in the axial direction of the rotor. Each sheet metal includes a ring-shaped yoke with a yoke outwardly directed in the radial direction of the yoke. On the outside of the yoke, a plurality of pole shafts are arranged at a distance from one another in the circumferential direction of the yoke. It is conceivable that the pole shafts are connected to the yoke in a material-to-material, form-fitting and/or force-fitting manner. Provision is particularly preferably made for the pole shafts to be connected and/or formed in one piece with the yoke. A prefabricated and/or pre-wound rotor winding can be or is arranged on each pole shaft. In this way, the rotor winding can be prefabricated separately, which means that the manufacturing time of the rotor can be accelerated. Thus, the manufacturing costs of the rotor can also be reduced.

Each pole shank has a pole shoe arranged and/or fastened on a pole shank end aligned in the radial direction. In other words, the pole shoe is formed separately from the pole shaft. Provision is also made for a gap opening between two pole shoes arranged next to one another in the circumferential direction of the rotor to be closed at least in sections in the axial direction of the rotor by a circumferential tube and/or by a web formed between the adjacent pole shoes. If a web is provided, the web connects two pole shoes arranged next to one another. Deformation of the pole shoe ends formed in the circumferential direction of the rotor can be reduced in a radial direction of the rotor during operation of the rotor via the webs. Under the influence of centrifugal force, there is a risk that the rotor winding arranged on the pole shaft will shift outwards in the radial direction and act against the pole shoes, as a result of which they can experience a slight outward deflection in the radial direction. In order to counteract a deflection of the pole shoe ends in the radial direction of the rotor, it is also possible to slide and/or shrink a circumferential tube onto the pole shoes. A center point of the tube corresponds to an axis of rotation of the rotor. The rigidity of the rotor can consequently be increased by the tube and/or the webs.

The rotor has a plurality of pole pieces. It is therefore conceivable that the rotor has two or more than two pole shafts. In an advantageous development of the invention, it is provided that the rotor has a star-shaped cross-section and has four pole shafts. Such a design can also be referred to as a rotor star. The pole shafts are arranged at regular intervals from one another on the outside of the yoke in the circumferential direction of the yoke. In this way, the pole shanks have a sufficiently large distance from one another in order to easily slide the prefabricated rotor winding over the pole shank end onto the respective pole shank. The prefabricated rotor winding is consequently plugged onto the respective pole shaft in a direction perpendicular to the longitudinal direction of the rotor.

After the rotor winding has been arranged on the respective pole shaft, an advantageous development of the invention provides that the pole shoe is or will be connected to the end of the pole shaft in a form-fitting, material-locking and/or force-fitting manner. The form fit can be produced by contours which are correspondingly formed on the pole shaft end and the pole shoe and which engage in one another. Such a contour can be, for example, a T-shaped connection structure or a dovetail-shaped connection. It is also conceivable that the pole shoe is fastened to the pole shaft via a connecting means, for example a screw or a rivet. A material connection, for example an adhesive connection, is also conceivable. The adhesive connection can preferably take place in combination with the positive connection and/or the non-positive connection.

In an advantageous development of the invention, it is provided that a pole shaft forms a pole tooth with a pole shoe arranged on the end of the pole shaft, with a pole tooth axis running in the radial direction of the rotor running centrally through each pole tooth, which divides each pole tooth into a first side and into a second side divided, wherein a flow barrier is formed exclusively on the first side or the second side. Various harmonics, for example the 2nd harmonic and/or the 3rd harmonic, can preferably be at least partially reduced via the flux barrier arranged and/or formed asymmetrically in the pole tooth, as a result of which the performance of the electrical machine can be increased.

The flux barrier is a closed-edge passage opening running through the pole tooth in the axial direction of the rotor. The passage opening can be unfilled or filled exclusively with air. It is also conceivable that the passage opening is at least partially, preferably completely, filled. The filling of the passage opening can contain or have a ferrite and/or comprise an alloy of neodymium, iron, boron (NdFeB). It is also conceivable that the filling contains an alloy of samarium (Sm) with the metal cobalt (Co).

It is advantageously provided that the flux barrier is formed exclusively in the pole shoe.

In a preferred embodiment of the invention, it is provided that the at least one flux barrier of the pole shoe is a circular and/or an elliptical passage opening. The passage opening is consequently closed at the edge. Notch stresses in the pole tooth can be reduced by the circular and/or elliptical configuration. This can increase the longevity of the rotor.

It is conceivable that the web between two pole shoes is formed in one piece with the pole shoes. For example, laminations of the rotor are provided, which are punched out, taking into account the formation of the web between the pole shoes.

In this context, it can be provided that not every sheet has a web, but for example every second, every third, every fourth, every fifth or every nth sheet, where n is preferably ≦50, preferably ≦40 and particularly preferably ≦25 . The respectively adjoining metal sheet or metal sheet lying in between is then designed without webs. Thus, the gap opening is partially or partially closed in the axial direction of the rotor. The risk of magnetic short circuits between the poles of the rotor can thus be minimized and/or reduced.

Alternatively and/or in addition to this, it is conceivable that a plurality of laminations arranged directly next to one another are formed in such a way that the web and the pole shoe or the pole shoes are formed in one piece and then further laminations follow which are formed without webs. It is therefore conceivable that preferably 5 sheets with a web are formed and then 5 sheets follow that are formed without webs. The number of rib-free sheets can differ from the number of sheets with ribs. Consequently, it is preferably conceivable that 10 metal sheets are formed with webs and then preferably 5 metal sheets without webs. The gap opening is thus closed in sections, as a result of which magnetic short circuits between the poles of the rotor can be reduced and/or avoided.

An advantageous development of the invention is that the web and/or the tube are made of a non-conductive material. This also reduces the risk of short circuits between the poles of the rotor being established and/or caused by the web or the tube. The non-conductive material may be a plastic material and/or a resin material. It is conceivable that the plastic material and/or the resin material is fiber-reinforced. Provision can therefore advantageously be made for the encircling tube and/or the web to have carbon fibers and/or glass fibers. Webs and tubes made of plastic or resin that are also fiber reinforced can have reduced weight and also increased structural rigidity.

According to a second aspect, the invention relates to an electric machine for a motor vehicle with the rotor according to the invention.

The electric machine is preferably arranged in a traction drive, in particular in an axle drive.

According to a third aspect, the invention relates to a motor vehicle with the electric machine according to the invention.

The motor vehicle is preferably an at least partially, preferably completely, electrically powered motor vehicle. The electrical machine is preferably part of a traction drive of the motor vehicle.

• - Ausstanzen von Blechen, die ein Joch mit den auf der Jochaußenseite ausgebildeten Polschäften aufweisen;
• - Aufeinanderstapeln der Bleche;
• - Vorwickeln einer Rotorwicklung;
• - Aufstecken der vorgewickelten Rotorwicklung auf den jeweiligen Polschaft;
• - Anordnung des jeweiligen Polschuhs auf dem entsprechenden Polschaft;
• - Aufschieben und/oder aufwickeln eines umlaufenden Rohres auf die Polschuhe und/oder Anordnung eines Steges zwischen zwei benachbarte Polschuhe, um die Spaltöffnung zwischen den Polschuhen zumindest abschnittsweise in Längsrichtung des Rotors zu verschließen.

According to a fourth aspect, the invention relates to a method for producing the rotor according to the invention, comprising the steps:

• - Punching out metal sheets which have a yoke with the pole shanks formed on the outside of the yoke;
• - Stacking of the sheets;
• - Prewinding a rotor winding;
• - Attaching the pre-wound rotor winding to the respective pole shaft;
• - Arrangement of the respective pole shoe on the corresponding pole shaft;
• - Sliding and/or winding a rotating tube onto the pole shoes and/or arranging a web between two adjacent pole shoes in order to close the gap opening between the pole shoes at least in sections in the longitudinal direction of the rotor.

In other words, the manufacturing method according to the fourth aspect provides that the rotor winding is prefabricated. After the metal sheets have been stacked one behind the other in the axial direction and preferably connected to one another, the prefabricated rotor winding is slipped onto the pole shafts. The rotor winding is pushed or pushed onto the pole shaft in a direction perpendicular to the longitudinal direction of the rotor. The rotor production can be accelerated by the separate production of the rotor base body and the rotor winding. Thus, the manufacturing cost of the rotor can be reduced. After the rotor winding has been slipped onto the pole shafts, a pole shoe is arranged and/or attached to the respective end of the pole shaft. Subsequently, either a web is arranged between two mutually arranged pole shoes in order to at least partially close a gap between the adjacent pole shoes, based on the longitudinal direction of the rotor, and/or a tube is pushed over the pole shoes or the rotor. A deflection of pole shoe ends in the radial direction of the rotor caused by centrifugal force can be counteracted via the tube and/or the webs, as a result of which the rigidity of the rotor can be increased.

In an advantageous development of the invention, it is provided that the pole shoes are arranged on the respective pole shoe end in a materially bonded, form-fitting and/or non-positive manner.

Provision is advantageously made for the pole shoes to be plugged onto the end of the pole shoe in the axial direction of the yoke.

It should be noted that all features described above and below in relation to one aspect of the present invention apply equally to any other aspect of the present invention. In particular, all features of the rotor can also be features of the electrical machine, features of the motor vehicle and/or also features of the method. This also applies vice versa.

Further features and advantages of the present invention result from the dependent claims and the following exemplary embodiments len. The exemplary embodiments are not intended to be limiting, but rather to be understood as exemplary. They are intended to enable those skilled in the art to carry out the invention. The applicant reserves the right to make individual and/or several of the features disclosed in the exemplary embodiments the subject of patent claims or to include such features in existing patent claims. The exemplary embodiments are explained in more detail with reference to drawings.

• 1 einen Querschnitt durch einen Rotor in einer ersten Ausgestaltung,
• 2 einen Querschnitt durch den Rotor in einer zweiten Ausgestaltung,
• 3 ein Kraftfahrzeug mit einer den Rotor aufweisenden elektrischen Maschine,
• 4 ein Verfahren zur Herstellung eines Rotors.

In these show:

• 1 a cross section through a rotor in a first embodiment,
• 2 a cross section through the rotor in a second embodiment,
• 3 a motor vehicle with an electrical machine having the rotor,
• 4 a method of manufacturing a rotor.

In 1 a cross section through a rotor RO of a separately excited electrical machine EM for a motor vehicle KFZ is shown in a first embodiment. The rotor RO has a plurality of laminations BL arranged one behind the other in the axial direction of the rotor RO. Each metal sheet BL comprises a ring-shaped yoke JO with a yoke outside JAS directed outwards in the radial direction of the yoke JO. A plurality of pole shafts PST are arranged at a distance from one another in the circumferential direction of the yoke JO on the outside of the yoke JAS. The present rotor RO has a total of four pole shafts PST, which are arranged at regular intervals from one another on the outside of the yoke JAS in the circumferential direction of the yoke JO. Such a rotor RO can also be referred to as a rotor star.

The pole shafts PST are connected and/or formed in one piece with the yoke JO. The pole shafts PST can thus be connected to the yoke JO with increased rigidity, which can have a positive effect on the noise development, in particular the noise vibration harshness behavior, of the electrical machine EM. A prefabricated and/or prewound rotor winding RW is arranged on each pole shaft PST. The rotor winding RW is prefabricated separately from the rotor RO and is plugged onto the respective pole shaft PST in a direction perpendicular to the longitudinal direction of the rotor RO. The longitudinal direction of the rotor RO runs in the direction of an axis of rotation DA of the rotor RO. The prefabrication of the rotor winding RW allows the production time of the rotor RO to be accelerated. Thus, the cost of the rotor RO can also be reduced.

Each pole shaft PST has a pole shoe PSH arranged and/or fastened on a pole shaft end PSE aligned in the radial direction of the yoke JO. In other words, the pole shoe PSH is formed separately from the pole shaft PST. After the rotor winding RW has been arranged on the respective pole shaft PST, the pole shoe PSH is pushed onto the respective pole shoe end PSE in a form-fitting manner in the longitudinal direction of the rotor RO. The positive connection can be produced by connecting contours VK which are correspondingly formed on the pole shaft end PSE and the pole shoe PSH and which engage in one another. Such a connection contour VK can, for example—as shown—be a T-shaped connection. However, other connection contours VK, such as a dovetail-shaped connection, are also conceivable.

Provision is also made for a gap opening SO between two pole shoes PSH arranged next to one another in the circumferential direction of the rotor RO to be closed at least in sections in the axial direction of the rotor RO by a web ST formed between the adjacent pole shoes PSH. The web ST can be braced between two adjacent pole shoes PSH and/or engage in them, so that it is held in a form-fitting manner between the two adjacent pole shoes PSH. Deformation of the pole shoe ends PSE formed in the circumferential direction of the rotor RO in a radial direction of the rotor RO during operation of the rotor RO can be reduced via the webs ST. Under the influence of centrifugal force, there is a risk that the rotor winding RW arranged on the pole shaft PST will shift outwards in the radial direction and act against the pole shoe ends PSE, as a result of which they can undergo a slight outward deflection in the radial direction. Thus, the rigidity of the rotor RO can be increased. In addition, the air gap between the rotor RO and a stator (not shown) surrounding the rotor RO can be reduced if a deformation of the pole shoe ends PSE in the radial direction is minimized, as a result of which the performance of the electrical machine EM can be increased.

To increase the performance of the electrical machine EM, it is also provided that a pole tooth axis PZA runs centrally through the pole shaft PST and the pole shoe PSH in the radial direction of the rotor RO, which has a pole tooth PZ formed by the pole shaft PST and the pole shoe PSH in a first side ES and divided into a second page ZS. A flux barrier FS is formed in the second side ZS of the pole tooth PZ, in particular in the pole shoe PSH. There is no flow lock FS on the first page ES. In other words, the first side ES of the pole tooth PZ is flow trained without barriers. Various harmonics, for example the 2nd harmonic and/or the 3rd harmonic, can preferably be at least partially reduced via the flux barrier FS arranged and/or formed asymmetrically in the pole tooth PZ, as a result of which the performance of the electrical machine EM can be increased.

2 shows a cross section through the rotor RO for an electric machine EM of a motor vehicle KFS in a second embodiment. Unlike that 1 the gap opening SO between two adjacent pole shoes PSH is not closed by a web ST, but by a circumferential tube UR that is pushed and/or shrunk onto the pole shoes PSH. A center point of the tube UR corresponds to the axis of rotation DA of the rotor RO. The tube UR can be used to prevent the pole shoe ends PSE from deforming outwards in the radial direction of the rotor RO under the influence of centrifugal force. The tube UR can be arranged as an alternative to the webs ST. However, it is also conceivable that both the webs ST and the tube RO are arranged accordingly.

In 3 an at least partially electrically driven motor vehicle KFZ is shown. The motor vehicle KFZ has a traction drive TA with an electric machine EM. In the electrical machine EM is a rotor RO, as for example in the 1 or 2 is shown arranged.

In 4 a method of manufacturing a rotor RO is shown.

In a first step 100, a plurality of metal sheets BL are stamped out, the metal sheets BL each having a yoke JO with the pole shafts PST formed on the outside of the yoke JAS.

In a second step 110, the metal sheets BL are stacked on top of one another and connected to one another. The connection can preferably be an adhesive connection, a welded connection and/or a caulked connection.

In a third step 120, a rotor winding RW is pre-wound. The process steps can be optimized and accelerated by the prefabrication of the rotor winding RW, since the winding process of the winding WL can take place independently of the stacking of the laminations BL.

In a fourth step 130, the prefabricated rotor winding RW is plugged onto the respective pole shaft PST in a direction perpendicular to the longitudinal direction of the rotor RO.

In a fifth step 140, a pole shoe PSH is arranged on a respective pole shaft end PSE, against which the rotor winding RW can be supported during operation of the electrical machine EM and under the influence of centrifugal force in the radial direction of the rotor RO.

In a sixth step 150, after the pole shoes PSH have been arranged on the pole shaft ends PSE, a web ST is arranged between two adjacent pole shoes PSH and/or a circumferential tube UR is pushed or wound onto the pole shoes PSH, at least around a gap opening SO between the pole shoes PSH to be closed in sections.

Claims (11)

Rotor (RO) for an externally excited electrical machine (EM) of a motor vehicle (KFZ), having a plurality of laminations (BL) arranged one behind the other in the axial direction of the rotor (RO), wherein Each metal sheet (BL) has a yoke (JO) of annular design with a yoke outside (JAS) pointing outwards in the radial direction of the yoke (JO), on the yoke outside (JAS) a plurality of pole shanks (PST) are arranged spaced apart from one another in the circumferential direction , on which a rotor winding (RW) can be arranged and/or is arranged, each pole piece (PST) has a pole piece (PSH) arranged and/or fixed on a pole piece end (PSE) aligned in the radial direction, wherein a gap opening (SO) between two pole shoes (PSH) arranged next to one another in the circumferential direction of the rotor (RO) via a circumferential tube (UR) and/or via a web (ST) formed between the adjacent pole shoes (PSH) at least in sections in the axial direction of the Rotors (RO) is closed. rotor after claim 1 , characterized in that the rotor (RO) is star-shaped in section and has four pole shafts (PST). Rotor according to one of the preceding claims, characterized in that the pole shoe (PSH) is connected to the pole shaft end (PSE) in a form-fitting, material-fitting and/or force-fitting manner. Rotor according to one of the preceding claims, characterized in that a pole shaft (PST) with a pole shoe (PSH) arranged on the pole shaft end (PSE) forms a pole tooth (PZ), centrally through each pole tooth (PZ) an in radial direction of the rotor (RO) running pole tooth axis (PZA), which divides each pole tooth (PZ) into a first side (ES) and a second side (ZS), with exclusively on the first side (ES) or the second side (ZS) a flow barrier (FS) is formed. rotor after claim 4 , characterized in that the flux barrier (FS) is formed exclusively in the pole shoe (PSH). Rotor after one of Claims 4 or 5 , characterized in that the flow barrier (FS) is a circular or elliptical passage opening. Rotor according to one of the preceding claims, characterized in that the web (ST) and/or the tube (UR) are made of a non-conductive material. rotor after claim 7 , characterized in that the encircling tube (UR) and/or the web (ST) has carbon fibers and/or glass fibers. Electrical machine (EM) for a motor vehicle (KFZ) with a rotor (RO) according to one of the preceding claims. Motor vehicle (KFZ) with an electric machine (EM) after claim 9 . Method for manufacturing a rotor (RO) according to one of Claims 1 until 8th , comprising the steps of: - stamping out metal sheets (BL) which have a yoke (JO) with the pole shanks (PST) formed on the yoke outside (JAS); - Stacking the sheets (BL); - winding a rotor winding (RW); - Attaching the rotor winding (RW) to the respective pole shaft (PST); - Arrangement of the respective pole shoe (PSH) on the corresponding pole shaft (PST); - Sliding and/or winding a rotating tube (UR) onto the pole shoes (PSH) and/or arranging a web (ST) between two adjacent pole shoes (PSH) around the gap opening (SO) between the pole shoes (PSH) at least in sections in the longitudinal direction of the rotor (RO) to close.

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