Device and method for fastening at least one magnet in a magnet holder of a rotor core of a rotor of an electrical machine

Abstract

Device for fastening at least one magnet (14) in a magnet receptacle (22) of a rotor core (12, 46) of a rotor (10) of an electrical machine, with a receptacle (44) which is designed to receive the rotor core (46) at least temporarily, an adjusting unit (48) which is designed to carry out a lifting movement in order to thereby change a distance between a tappet (38) and the rotor laminated core (46) arranged on the receptacle (44), an embossing unit (42) arranged on the tappet (38), which has at least one punch (84), wherein the embossing unit (42) is designed such that the punch (84) penetrates at least partially into the rotor laminated core (46) in the region of the magnet receptacle (22) due to the lifting movement and the magnet (14) is clamped in the magnet receptacle (22) by the material deformation thereby occurring in the edge region of the magnet receptacle (22), and with a control unit (32) which is designed to process an adjustment path variable and a pressure force variable and to control the adjustment unit (48) as a function of the adjustment path variable and the pressure force variable, wherein the adjustment path variable represents the adjustment path by which the plunger (38) and the rotor laminated core (46) move towards one another due to the lifting movement, and the pressure force variable represents the force with which the punch (84) presses onto the rotor laminated core (46).

Description

[0001] The invention relates to a device and a method for fastening at least one magnet in a magnet receptacle of a rotor core of a rotor of an electrical machine. Furthermore, the invention relates to a stamping unit designed for fastening at least one magnet in a magnet receptacle of a rotor core of a rotor of an electrical machine.

[0002] Electric machines can be used in a variety of ways, including, more recently, as drive motors in automotive engineering. These vehicles can be designed as hybrid vehicles or electric vehicles. In a hybrid vehicle, another drive unit, usually an internal combustion engine, is used alongside the electric motor. In contrast, an electric vehicle is powered exclusively by an electric motor. The electric machines used are generally designed as internal rotor machines, in which a rotatably mounted rotor is enclosed by a stationary stator. The stator generates a rotating magnetic field that drives the rotor. The rotor carries a rotor shaft, which is operatively connected to a drive shaft of the vehicle.

[0003] Synchronous machines, especially hybrid synchronous machines, can be used to drive a vehicle. The synchronous machine can be designed as a permanently excited synchronous machine with permanent magnets incorporated into the rotor. A hybrid synchronous machine is defined here as a permanently excited synchronous machine that also exhibits a pronounced reluctance effect, caused by a suitably selected rotor geometry, which is used to generate the torque acting on the rotor.

[0004] The rotor of an electrical machine designed as a synchronous machine or a hybrid synchronous machine is typically constructed from a large number of rotor laminations, which achieve particularly favorable magnetic field behavior. Typically, several rotor laminations are structurally combined to form a rotor lamination stack. The rotor laminations have magnet holders into which the magnets or permanent magnets are inserted.

[0005] Due to the sometimes extreme operating conditions that prevail for an electric machine used as a drive motor in automotive construction, in particular because the electric machine is operated at very high speeds, the permanent magnets are fixed in the magnet holders. A common procedure for this has been to glue the permanent magnets into the magnet holders. For example, DE 11 2004 000 027 T5 shows a motor production system with a rotor assembly device that includes a magnet incorporation section for incorporating magnets into the rotor core and an adhesive curing section for solidifying the magnets with an adhesive. However, this method of gluing the permanent magnets is disadvantageous in many respects. For example, a very large amount of effort is required to ensure process-reliable dosing and positioning of the adhesive in the magnet holders.Furthermore, bonding the permanent magnets is very time-consuming, as the adhesive must be allowed to harden before the rotor core can be subjected to subsequent processing steps. While this time can be reduced to a certain extent by accelerating the curing of the adhesive by heating the rotor core, this measure results in additional energy consumption and thus causes additional costs in the manufacture of a rotor and, consequently, in the manufacture of an electrical machine. Furthermore, if the permanent magnets are inserted into the magnet holders in an initially unmagnetized state rather than in their magnetized state, a great deal of effort is required to position and hold the initially unmagnetized magnets in the magnet holders before and during the adhesive curing process.Added to this are problems with recycling bonded permanent magnets. Firstly, it requires a relatively large amount of effort to remove bonded permanent magnets from a rotor core. Secondly, it is very time-consuming to clean a removed permanent magnet of any adhesive residue. Furthermore, the handling of the adhesives used for bonding is complex, with regard to dosing, curing, and storage. Another disadvantage is that the adhesives used to attach the magnets are relatively expensive due to the demands placed on them, particularly with regard to their temperature resistance. This leads to high costs in the manufacture of a rotor and consequently in the manufacture of an electrical machine.

[0006] DE 10 2011 101 730 A1 discloses an electric motor having a rotor with multiple poles, including pole shoes, and a magnetic yoke mechanically connected to the pole shoes by holding sections. A recess is provided between the magnetic yoke and a pole shoe, in which recess at least one permanent magnet is arranged to generate a magnetic flux in this pole shoe, so that a magnet-pole shoe boundary is defined at the transition from this permanent magnet to the associated pole shoe. Adjacent to the respective recess on each side of the at least one permanent magnet, approximately in the circumferential direction, is a region of poor magnetic conductivity that borders one of the holding sections. The holding sections are designed as spring elements that act on the pole shoes toward the associated permanent magnets in order to clamp the latter firmly in the recesses provided for them.

[0007] It is therefore an object of the present invention to provide a device and a method for fastening at least one magnet or permanent magnet in a magnet holder of a rotor core of a rotor of an electrical machine, with which the magnet can be fastened quickly, easily, and cost-effectively, and with which a high degree of fixation of the magnet in the magnet holder is simultaneously ensured. A further object is to enable simple, easy, and cost-effective recycling of magnets fastened in a rotor core.

[0008] This object is achieved by a device of the type mentioned above, which has the following means: a receptacle designed to at least temporarily receive the rotor laminated core, an adjustment unit designed to perform a lifting movement in order to thereby change a distance between a tappet and the rotor laminated core arranged on the receptacle, an embossing unit arranged on the tappet, which has at least one punch, wherein the embossing unit is designed such that the punch penetrates at least partially into the rotor laminated core in the region of the magnet receptacle due to the lifting movement and the magnet is clamped in the magnet receptacle by the material deformation thereby occurring in the edge region of the magnet receptacle, and a control unit designed to process an adjustment travel variable and a compressive force variable and to control the adjustment unit depending on the adjustment travel variable and the compressive force variable,where the adjustment travel represents the adjustment travel by which the ram and the rotor core move towards each other due to the stroke movement, and the pressure force represents the force with which the ram presses on the rotor core.

[0009] The task is further solved by a method of the type mentioned above, in which the following steps take place: - Arranging a stamping unit on a ram, wherein the stamping unit has at least one punch, - Arranging the rotor core on a holder, - Inserting at least one magnet into the magnet holder, - processing an adjustment path variable and a pressure force variable in a control unit, wherein the adjustment path variable represents the adjustment path by which the ram and the rotor core move towards each other due to a lifting movement, and wherein the pressure force variable represents the force with which the ram presses on the rotor core, - Controlling an adjustment unit depending on the adjustment path size and the pressure force size to carry out the lifting movement, so that the punch penetrates at least partially into the rotor laminated core in the area of ​​the magnet holder due to the lifting movement and the magnet is clamped in the magnet holder by the material deformation resulting in the edge area of ​​the magnet holder.

[0010] The device and method according to the invention are based on the idea of ​​fastening a magnet in a magnet holder of a rotor laminated core without additional auxiliary materials, i.e. without adhesive. Instead, the magnet is clamped and thus fastened in the rotor laminated core by forming the edge region of the magnet holder. This eliminates the effort required to meter and position the adhesive in the magnet holders. Furthermore, the time required to manufacture a rotor laminated core or a rotor is reduced because there is no need to wait until the adhesive has cured. The effort required to position and hold non-magnetized magnets in the magnet holders is also reduced because the measures required for a curing process are no longer necessary.The recycling of magnets installed in a rotor lamination stack is also easier because the magnets attached according to the invention can be removed from the rotor lamination stack much more easily and the removed magnets are not contaminated by adhesive residues. Since the special measures required for handling the adhesives used for bonding with regard to dosing, curing, and storage of the adhesives are eliminated, the attachment of magnets in the magnet holders of a rotor lamination stack is simplified overall. By eliminating the relatively expensive adhesives, the costs for manufacturing a rotor and consequently for manufacturing an electrical machine are reduced. In addition, the attachment of a magnet in a magnet holder according to the invention enables a highly reliable magnet assembly despite its simplicity.Another advantageous aspect is that by eliminating the use of adhesives when attaching the magnets, the production of the rotor cores and thus of the electrical machine as a whole becomes more environmentally friendly, since no solvents originating from adhesives are released.

[0011] The above-mentioned task is therefore completely solved.

[0012] Before advantageous embodiments of the invention are presented, individual aspects of the fastening of magnets according to the invention in a magnet holder of a rotor laminated core will be explained in advance.

[0013] The rotor lamination stack arranged on the holder and the plunger are arranged or aligned with each other in such a way that a longitudinal axis of the plunger and a surface of the rotor lamination stack are orthogonal to each other, or such that the longitudinal axis is parallel to a surface normal of the surface of the rotor lamination stack and thus to an axial direction of the rotor lamination stack. At the same time, the embossing unit on the ram and the punch in the embossing unit are each arranged in such a way that a longitudinal axis of the punch is parallel to the longitudinal axis of the ram. Consequently, the punch penetrates the rotor lamination stack in the axial direction due to the lifting movement. The force thus introduced into the rotor lamination stack in the axial direction initially results in an axial material flow in the rotor lamination stack below the punch, which, with increasing penetration depth, leads to a certain extent to a radial material flow towards the magnet to be attached.The rotor laminated core is therefore deformed in both the axial and radial directions, with the deformation being significantly greater in the axial direction than in the radial direction. The stamping unit is preferably designed such that the punch penetrates the rotor laminated core at the edge region of the magnet holder that faces the inside of the magnet, as viewed in the radial direction. The material flow in the radial direction then causes the magnet to rest on the side of the magnet holder that is located on the outside in the radial direction. In other words: the magnet is pushed outwards within the magnet holder and thus clamped. As a result, the magnet can support itself on this side during operation of the electrical machine due to the centrifugal forces that occur. According to the invention, the magnet is fastened in the magnet holder by partially forming the rotor laminated core.According to the invention, the magnet is fixed in the magnet holder by a forming process known as embossing, whereby for this purpose at least one embossing point is set or introduced into the rotor core.

[0014] In an advantageous embodiment of the invention, the control unit is designed to control the adjustment unit such that the lifting movement is initially carried out as a function of the compressive force magnitude and then, after a criterion predetermined for the compressive force magnitude has been met, as a function of the adjustment travel magnitude. This two-stage procedure has the following advantage: Because the lifting movement is initially carried out as a function of the compressive force magnitude, it is ensured that the rotor laminated core is clearly fixed in relation to the punch. At the same time, this means that when the punch penetrates and thus when the rotor laminated core is deformed, setting processes do not occur, which could occur due to the material transitions that exist within a rotor laminated core because it is made up of a large number of individual rotor laminations. This ensures reproducible penetration of the punch into the rotor laminated core.The subsequent stroke movement, which is dependent on the adjustment range, ensures reproducible material deformation in both the axial and radial directions. Reproducible radial material deformation is of great importance for reliable fastening of the magnets in the magnet holder. Overall, this measure enables process-reliable fastening of the magnets while simultaneously ensuring a high degree of fixation strength.

[0015] In a further embodiment of the aforementioned measure, the criterion is the achievement of a specified threshold value for the compressive force. This ensures that the rotor core is fixed with a defined clamping force, which is also sufficiently large to prevent any settling during the actual deformation or forming process.

[0016] Advantageously, after the criterion specified for the pressure force magnitude has been met, the adjustment unit is controlled until the adjustment travel value meets a specified criterion. Preferably, the adjustment unit is controlled until the plunger and the rotor core have moved toward each other by a specified adjustment travel due to the stroke movement performed after the criterion specified for the pressure force magnitude has been met.

[0017] In a further embodiment of the invention, the adjustment unit is designed to move the plunger. Because the plunger, and not the rotor core, is moved, the point at which the punch penetrates the rotor core can be set more precisely, since the plunger with the stamping unit arranged on it can be moved more precisely and thus with less deviation than the holder with the rotor core arranged on it. This allows the penetration points or penetration locations to be positioned more precisely with respect to the edge area of ​​the magnet holder, resulting in a more reliable and thus better reproducible fastening of the magnet in the magnet holder.

[0018] Consequently, in the aforementioned embodiment, the device comprises a displacement sensor designed to detect the displacement traveled by the ram due to the lifting movement. This measure makes it easy to determine the displacement traveled by the ram and the rotor core, or more precisely, by which the ram is moved towards the rotor core. Since the stamping unit is firmly connected to the ram, and the punch is in turn firmly connected to the stamping unit, the displacement traveled by the ram also corresponds to the distance traveled by the punch. Consequently, the penetration depth of the punch into the rotor core can be easily detected and thus monitored.Alternatively, compliance with a specified penetration depth can also be ensured by, for example, providing a fixed stop on the embossing unit that represents the required penetration depth.

[0019] In a further embodiment of the invention, the holder is designed as an additional stamping unit. This feature allows a stamp to penetrate both the surface of the rotor core facing the tappet and the surface of the rotor core facing away from the tappet with a single stroke. Thus, the magnet can be secured in the magnet holder from both sides with a single stroke. No reclamping of the rotor core is required, resulting in short production times.

[0020] In a further advantageous embodiment, the embossing unit has a plurality of stamps. Depending on the design of the embossing unit or the arrangement of the stamps within the embossing unit, this makes it possible, for example, to simultaneously set multiple stamping points on a magnetic holder with a single stroke, thus securing the magnet at multiple locations. In an alternative embodiment, it is possible to set stamping points on multiple magnetic holders with a single stroke. A combination of both is also conceivable.

[0021] In a further embodiment of the invention, the stamping unit is designed such that the punch is initially concealed within the stamping unit and only partially emerges from the stamping unit after the stamping unit is in contact with the rotor core due to the lifting movement. This measure enables optimal prestressing and thus fixation of the rotor core before the actual deformation or forming process takes place.

[0022] In an advantageous embodiment, the embossing unit has at least one spring. This allows the preload force to be adjusted or built up in a defined and reproducible manner. This ensures reliable fastening of the magnets and, at the same time, a high degree of fixation strength.

[0023] In a further embodiment of the invention, the stamping unit has at least one force sensor operatively connected to the stamp. This enables particularly precise determination of the force with which the stamp presses into the rotor core. This measure also ensures process-reliable fastening of the magnets while simultaneously ensuring high fixation strength.

[0024] Preferably, the embossing unit which is used in the device according to the invention or is used within the scope of the method according to the invention has the following components: a receiving element which is designed to fasten the embossing unit to a ram or to a receptacle, a punch holding element on which at least one punch is arranged, a contact element which is movably connected to the punch holding element via at least one guide, wherein the contact element has an opening through which the punch can pass at least partially, and at least one spring which is arranged between the punch holding element and the contact element and which keeps the punch holding element and the contact element spaced apart from one another.The stamping unit designed in this way, which can also be referred to as a stamping tool, ensures, on the one hand, a defined build-up of the preload force and, on the other hand, a defined penetration of the stamp and thus a defined adjustment of the stamp's penetration depth into the rotor core. Preferably, the further stamping unit is constructed identically.

[0025] As already explained, the adjustment unit is preferably designed such that the plunger is moved and thus moves towards the rotor core arranged on the holder. To implement the movement of the plunger, the adjustment unit is correspondingly controlled by the control unit. This control is advantageously carried out in two stages or is divided into two sections. In a first stage or in a first section, the control takes place depending on the compressive force value, i.e. the compressive force value is evaluated and thus the compressive force is monitored. This first stage or this first section ends when a predetermined criterion for the compressive force value is met, in particular when the compressive force value has reached or exceeded a predetermined threshold value. In the subsequent second stage or in the second section, the control takes place depending on the adjustment travel value, i.e.the adjustment travel is evaluated and thus the adjustment travel is monitored. To do this, the adjustment travel is first set to zero, i.e. the value of the adjustment value that exists at the time at which the compressive force has reached or exceeded the specified threshold value is overwritten by the value zero. The ram is then moved further towards the rotor laminated core until the zeroed adjustment travel corresponds to a specified value or reference value that corresponds to the required or desired penetration depth of the punch into the rotor laminated core. Overall, this can achieve this: the rotor laminated core is first compressed by the stamping unit with a defined, specified preload force (first stage or first section) and then the punch penetrates or moves into the rotor laminated core to a defined, specified penetration depth (second stage or second section).Preferably, the movement of the ram is continuous, meaning there is no interruption in movement during the transition from the first to the second stage or between the two sections. Furthermore, the threshold value for the compressive force is selected such that the preload force established at the end of the first stage or section does not correspond to the spring force that the spring contained in the stamping unit would generate if the stamp holding element and the contact element were in contact with each other.

[0026] At this point, it should be explained how the formulation used in connection with the adjustment travel variable should be understood, which states that the tappet and the rotor laminated core move towards each other due to the lifting movement. This formulation should not be understood to mean that both components, i.e. the tappet and the rotor laminated core, are necessarily moved simultaneously. Rather, this formulation is intended to express that the distance between these two components is changed, which can be achieved by moving at least one of the two components, i.e. either the tappet or the rotor laminated core. It is also conceivable, however, to move both components simultaneously. Preferably, however, only the tappet is moved.

[0027] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 the structure of a rotor of an electrical machine using two partial figures, Fig. 2 the basic arrangement of first and second magnet holders in a rotor core, Fig. 3 a schematic representation of the device according to the invention, Fig. 4 a schematic representation of an embossing unit used in the device according to the invention, Fig. 5 Detailed representations of first and second permanent magnets mounted in a rotor core with differently arranged embossing points, Fig. 6 a further detailed view of a first and second permanent magnet fastened in a rotor core with embossed points.

[0028] Fig. 1 consists of two sub-figures. Fig. 1a shows an exploded view of the essential components from which a rotor 10 of an electrical machine (not shown) is constructed. In the present exemplary embodiment, the electrical machine is a synchronous machine, in particular a hybrid synchronous machine. The rotor 10 is typically constructed from rotor lamination stacks 12, with permanent magnets 14 inserted into each of the rotor lamination stacks 12. The rotor lamination stacks 12, in turn, are each constructed from a plurality of rotor laminations (not shown). The rotor lamination stacks 12 are arranged between two support disks 16. The rotor lamination stacks 12 and the support disks 16 are connected to one another by screws 18 and associated nuts 20. Each screw 18 and nut 20 together form a connecting element. Fig. 1b shows the assembled rotor 10.

[0029] In Fig. 2 shows a rotor lamination stack 12. The rotor lamination stack 12 has magnet receptacles 22, which are also referred to as caverns or magnetic pockets. The magnet receptacles 22 are designed in two types: as first magnet receptacles, one of which is designated by the reference numeral 22a, and as second magnet receptacles, one of which is designated by the reference numeral 22b. First permanent magnets 14a are incorporated into the first magnet receptacles 22a, and second permanent magnets 14b are incorporated into the second magnet receptacles 22b. For reasons of clarity, Fig. 2, the first and second permanent magnets 14a, 14b are not shown. Adjacent first permanent magnets 14a preferably have different installation positions and thus different magnetic polarity. The same applies to the second permanent magnets 14b.

[0030] A circle marked with the reference number 24 marks a partial area 26 of the rotor core 12, which will be discussed further below in connection with the Fig. 5, in which this partial area is shown enlarged. The arrangement of embossed points introduced into the rotor core 12 in the area of ​​the magnet receptacles 22 using the device according to the invention is described with reference to partial area 26.

[0031] In Fig. 3, a device according to the invention is designated in its entirety by the reference numeral 28, wherein the device 28 has a press 30 and a control unit 32 associated therewith. The press 30 has a base 34, in particular a C-shaped base, and a stand 36. A ram 38 is movably mounted in the stand 36. A stamping unit 42 is attached to the ram 38 by means of a tool holder 40. The base 34 has a holder 44 designed to receive a rotor core. Fig. 3 shows a rotor core 46 arranged on the receptacle 44. Furthermore, the device 28 has an adjusting unit 48 which is designed to perform a lifting movement in order to thereby change a distance between the tappet 38 and the rotor core 46. The lifting movement is in Fig. 3 by an arrow 50. The control unit 32 is designed to control the adjustment unit 48, which in Fig. 3 is indicated by a connection 52. The representation chosen in this regard is not intended to have a limiting effect; of course, further components contained in the press 30 can be controlled via the control unit 32. Preferably, the adjustment unit 48 is designed to move the ram 38.

[0032] With regard to the control of the adjustment unit 48, the control unit 32 is designed such that an adjustment path variable and a pressure force variable are processed for this purpose, wherein the control takes place depending on these two variables. The adjustment path variable represents the adjustment path by which the plunger 38 and the rotor core 46 move towards each other due to the lifting movement. Since the stamping unit 42 is attached to the plunger 38, the adjustment path variable similarly represents the adjustment path by which the stamping unit 42 or a stamp arranged therein, which will be described later, and the rotor core 46 move towards each other. The pressure force variable represents the force with which the stamp, which will be described later, presses on the rotor core 46. As can be seen from the illustration in Fig. 3, the device 28 has a displacement sensor 54, which is designed to detect the displacement traveled by the plunger 38 due to the stroke movement. The pressure sensor, which is provided for detecting said force, is referred to in connection with Fig. 4 received.

[0033] The control unit 32 is configured to control the adjustment unit 48 such that the lifting movement is initially performed as a function of the pressure force magnitude and subsequently, after a criterion predefined for the pressure force magnitude has been met, as a function of the adjustment travel magnitude. This criterion may be the reaching of a threshold value predefined for the pressure force magnitude.

[0034] As the above explanations show, the adjustment unit 48 is designed as a lifting unit, in such a way that the lifting movement is composed of a first partial movement and a second partial movement following the first partial movement, wherein the first partial movement is realized as a function of the pressure force magnitude and the second partial movement as a function of the adjustment path magnitude.

[0035] Preferably, the holder 44 is designed as a further stamping unit. With this configuration, it is possible to machine the rotor core 46 simultaneously from both sides, i.e., with respect to its arrangement within the press 30, from above and below.

[0036] Fig. 4 shows, in the form of a sectional view, a schematic representation of an embossing unit 42 used in the device 28 according to the invention. The embossing unit 42 has a receiving element 58, with which it is fastened to a tool holder 40 assigned to the ram 38. Thus, the embossing unit 42 is at least indirectly fastened to the ram 38. The embossing unit 42 further has a punch holding element 62, which is connected to the receiving element 58 via a pressure plate 64. The receiving element 58, the pressure plate 64, and the punch holding element 62 form a first structural unit 66, which can be referred to as the upper structural unit due to its arrangement on the ram 38.

[0037] Furthermore, the embossing unit 42 has a contact element 68, via which the embossing unit 42 rests on the rotor core 46 during the fastening of the magnets. With reference to the above nomenclature, the contact element 68 represents a second or lower structural unit. The contact element 68 is movably connected to the punch holding element 62 via guides 70, preferably at least two. The guides 70 each consist of a guide bore 72 arranged in the punch holding element 62 and a guide pin 74 connected to the contact element 68. The contact element 68 is secured to the punch holding element 62 via screws 76. For this purpose, the screws 76 are each screwed into screw holding elements 78, wherein the screw holding elements 78 are connected to the punch holding element 62. Springs 80 are arranged between the screw holding elements 78 and the contact element 68 or between the punch holding element 62 and the contact element 68.The springs 80 are compression springs, preferably designed as helical springs. As shown in . Fig. 4, in each case it should be a spring 80 surrounding the screw 76, i.e. the screw 76 is arranged within the spring 80. However, this should not have a restrictive effect. Furthermore, it is conceivable that only a single spring 80 is arranged between the contact element 68 and the punch holding element 62. In other words: the stamping unit should have at least one spring 80. Regardless of the number of springs actually used and their concrete design or arrangement within the stamping unit, the purpose of the at least one spring 80 is to create a gap 82 between the punch holding element 62 and the contact element 68. The at least one spring 80 holds the punch holding element 62 and the contact element 68 at a distance from one another. The spring or springs are preferably designed such that they generate a pretensioning force of approximately 6 to 9.5 kN.

[0038] The embossing unit 42 has at least one punch 84, which is fastened by its fixed end in the punch holding element 62. A force sensor 86 is arranged at the fixed end of the respective punch 84. In other words, the embossing unit 42 has at least one force sensor 86 operatively connected to the punch 84. At its free end, the punch 84 has a punch tip 88. The contact element 68 has a raised portion 90 in which openings 92, designed as through-bores and arranged in the contact element 68, end, through which openings the punches 84 can partially pass.

[0039] The Fig. The embossing unit 42 shown in Figure 4 is designed to fasten at least one magnet in a magnet receptacle of a rotor laminated core of a rotor of an electrical machine. For this purpose, the embossing unit 42 arranged on the tappet 38 has at least one punch 84, wherein the embossing unit 42 is designed such that the punch 84 penetrates at least partially into a (not shown) rotor laminated core in the region of a (not shown) magnet receptacle due to a lifting movement of the tappet 38 and the magnet is clamped in the magnet receptacle by the material deformation thereby occurring in the edge region of the magnet receptacle. For this purpose, the embossing unit 42 is designed such that the punch 84 is initially concealed in the embossing unit 42 and only emerges at least partially from the embossing unit 42 after the embossing unit 42 is in contact with the (not shown) rotor laminated core due to the lifting movement.The partial protrusion of the punch 84 is to be understood as meaning that at least a part of the punch tip 88 protrudes through the opening 92 from the contact element 68.

[0040] The Fig. 4, which shows a stamping unit 42 which is attached to a ram 38, and thus with reference to the illustration in Fig. 3 acting from above on the rotor core 46 should not have any restrictive effect. This also applies to the statements made in this regard. These statements also apply accordingly in the case where the receptacle 44 is designed as a further stamping unit, and thus with reference to the illustration in Fig. 3, the stamping unit acts from below on the rotor core 46. These statements also apply in the case where a stamping unit 42 is attached to the holder 44, for example via a holder element directly on the holder 44 or on a tool holder assigned to the holder 44. In both cases, the Fig. 4 arrangement is rotated by 180°, ie the stamps 84 would not be as in Fig. 4 shown from top to bottom, but from bottom to top into the rotor core.

[0041] The Fig. 4 with regard to the force sensor, the representation chosen has no restrictive effect. According to Fig. 4, the at least one force sensor is arranged in the stamping unit. Alternatively, the force sensor can also be arranged in the press itself, for example, in the area of ​​the stand.

[0042] Fig. 5 consists of five Fig. 5a to 5e, each of which, according to the explanations to Fig. 2, shows a partial area 26 of a rotor core 12 in an enlarged view. Each of the Fig. 5a to 5e each has a first magnet receptacle 22a and a second magnet receptacle 22b. A first permanent magnet 14a is inserted in the first magnet receptacle 22a and a second permanent magnet 14b is inserted in the second magnet receptacle 22b. The first and second permanent magnets 14a, 14b are fastened in the magnet receptacles 22a, 22b by means of embossed points 94. The two permanent magnets 14a, 14b shown are arranged according to a first installation position or polarity. Permanent magnets adjacent to these, ie arranged in an adjacent magnet receptacle, are arranged according to a second installation position or polarity. The permanent magnet shown in the Fig. The gap between the magnet holders and the permanent magnets, which can be seen in Figures 5a to 5e, should not have any restrictive effect. Fig. In Figures 5a to 5e, the embossing points 94 are shown without the radial material flow caused by the embossing, since these partial figures are only intended to show different arrangement possibilities of the embossing points. Fig. 5a shows a previously selected arrangement of the embossing points 94, whereas the Fig. 5b to 5e show new arrangements of the embossing points 94, which are distinguished from the previously chosen arrangement by the fact that the permanent magnets are held in the magnet receptacles with a greater holding force.

[0043] In Fig. 5a, both the first embossing points 94a assigned to the first magnet receptacle 22a and the second embossing points 94b assigned to the second magnet receptacle 22b are each arranged in the region of the corners of the magnet receptacles. With respect to a perpendicular bisector defined for the first magnet receptacle 22a or the first permanent magnet 14a, the first embossing points 94a are very far away, preferably at a maximum distance from this. The same applies to the second magnet receptacle 22b or the second permanent magnet 14b, although for reasons of clarity, the depiction of a perpendicular bisector assigned to these has been omitted. Fig. In figures 5b to 5e, the representation of the perpendicular bisector was also omitted for reasons of clarity.

[0044] In Fig. 5b, the first and second embossing points 94a, 94b are moved further into the center region of the first and second magnet receptacles 22a, 22b and the first and second permanent magnets 14a, 14b, respectively. This is the preferred arrangement of the embossing points, since the holding force acting on the permanent magnets is greatest in this arrangement.

[0045] In Fig. 5c, only one embossing point 94a, 94b is provided for each of the first and second magnet receptacles 22a, 22b or for each of the first and second permanent magnets 14a, 14b, which is preferably arranged centrally and thus on the perpendicular bisector.

[0046] In Fig. 5d, in turn, two embossing points 94a, 94b are provided for the first and second magnet receptacles 22a, 22b and the first and second permanent magnets 14a, 14b, respectively, which, in comparison to the Fig. 5b are arranged at an even smaller distance from the perpendicular bisector.

[0047] In Fig. 5e shows another alternative arrangement of the embossing points. For the second magnet holder 22b or the second permanent magnet 14b, the second embossing points 94b are arranged as shown in Fig. 5d. In contrast, the first permanent magnet 14a arranged in the first magnet receptacle 22a is fastened via three first embossing points 94a, of which the middle embossing point is preferably arranged on the perpendicular bisector and the two outer embossing points as shown in Fig. 5d are arranged. The Fig. The arrangement of the second embossing points 94b shown in Figure 5e is merely exemplary. Of course, the second embossing point(s) can also be arranged as shown in the Fig. 5b or Fig. 5c shown.

[0048] As shown in the Fig. As can be seen from Figures 5b to 5e, the permanent magnets can be attached with a different number of embossing points in the respective magnet receptacles. Accordingly, an embossing unit has at least one stamp for each magnet receptacle. Advantageously, a single embossing unit simultaneously attaches both the first permanent magnet arranged in a first magnet receptacle and the second permanent magnet arranged in a second magnet receptacle. Accordingly, one embossing unit has stamps associated with both the first magnet receptacle and the second magnet receptacle. In a preferred embodiment, a single embossing unit simultaneously attaches the permanent magnets arranged therein for both two first magnet receptacles and two second magnet receptacles, which means that this embossing unit has a corresponding number of stamps. With reference to the exemplary illustration in Figure 。 Fig. 4 this means that the embossing unit shown there must be adapted accordingly, depending on how many magnet holders the permanent magnets are to be attached to at the same time with a single stroke movement, or with how many embossing points per magnet holder this is to be done.

[0049] The arrangement of embossing points in relative proximity to the perpendicular bisector has the advantage that embossing points arranged in this way cause less magnetic field disturbance because there is only a slight or no narrowing of the air gap.

[0050] Fig. 6 shows a first permanent magnet 14a, which is secured in a first magnet receptacle 22a by means of first embossing points 94a, and a second permanent magnet 14b, which is secured in a second magnet receptacle 22b by means of second embossing points 94b. In Fig. 6, the embossing points 94a, 94b are deliberately not shown as circular. Rather, the embossing points are shown elliptically, with the major semi-axis of the ellipse aligned orthogonally to the respective magnet receptacle or to the permanent magnet arranged therein. This representation is intended to illustrate the material flow that occurs when the permanent magnets are attached by the punches penetrating the rotor laminated core. The punch penetrates the rotor laminated core in the axial direction. This introduces a force into the rotor laminated core in the axial direction. The material flow occurs predominantly or initially in the axial direction and then, i.e. to a small extent in the radial direction, towards the magnet receptacle or to the permanent magnet to be attached. The material flow in the radial direction results from the fact that, due to the material flow in the axial direction, the material that was initially moved in this way increasingly deflects in the radial direction.The material flow in the radial direction ensures that the permanent magnet rests on the outside of the magnet holder, whereby the magnet is supported there during operation of the electrical machine due to the centrifugal forces that occur.

[0051] At this point, the process of attaching permanent magnets to magnet receptacles of a rotor laminated core is summarized again: First, at least one permanent magnet is positioned in a magnet receptacle of a rotor laminated core, with the rotor laminated core being arranged on a receptacle. By means of an embossing unit arranged on a ram, the rotor laminated core is deformed in the region of the magnet receptacle, namely by a punch that penetrates the rotor laminated core in the axial direction. Preferably, the receptacle is designed as an additional embossing unit or, alternatively, an additional embossing unit is arranged on the receptacle, so that the deformation of the rotor laminated core in the region of the magnet receptacle takes place on both sides of the rotor laminated core. With respect to one side of a magnet receptacle, a permanent magnet can be attached with one, two, or a larger number of embossing points.The punch tips can preferably be cylindrical, alternatively conical or pyramidal. With the device and method according to the invention, permanent magnets are fastened in a rotor core by stamping. The permanent magnets to be inserted into the magnet receptacles can be either already magnetized or unmagnetized. If the permanent magnets to be inserted are already magnetized, the fastening of the permanent magnets according to the invention is simplified in that they are held automatically in the magnet receptacle due to the development of a magnetic force during the fastening process referred to as stamping. If, on the other hand, the permanent magnets to be inserted are not magnetized, then these permanent magnets must be held by appropriate measures until they are held due to the material deformation occurring during stamping.

[0052] As already explained, preferably, embossing points are placed on the rotor core stack from both sides simultaneously. Furthermore, this is preferably done simultaneously for two first magnet holders and two second magnet holders. If the permanent magnets are attached to each magnet holder using two embossing points ( Fig. 5b or Fig. 5d), this means that sixteen stamping points are simultaneously applied with a single stroke. Advantageously, the penetration depth of a stamp is less than the width of the gap formed between the contact element and the stamp holding element, preferably less than 1 mm. List of reference symbols 10 Rotor 12 rotor lamination stack 14 Permanent magnet 16 Support disc 18 screw 20 mother 22 Magnetic holder 24 Circle 26 sub-area 28 Device 30 Press 32 Control unit 34 Substructure 36 stands 38 tappets 40 tool holder 42 embossing unit 44 recording 46 rotor lamination stack 48 adjustment unit 50 arrows 52 Connection 54 displacement sensor 58 receiving element 62 Stamp holding element 64 printing plate 66 first building unit 68 Investment element 70 leadership 72 guide hole 74 Guide pin 76 screw 78 Screw holding element 80 spring 82 gap 84 stamps 86 force sensor 88 stamp tip 90 Survey 92 Opening 94 embossing point 96 perpendicular bisectors

Claims

[1] Device for fastening at least one magnet (14) in a magnet receptacle (22) of a rotor core (12, 46) of a rotor (10) of an electrical machine, with a receptacle (44) which is designed to receive the rotor core (46) at least temporarily, an adjusting unit (48) which is designed to carry out a lifting movement in order to thereby change a distance between a tappet (38) and the rotor laminated core (46) arranged on the receptacle (44), an embossing unit (42) arranged on the tappet (38), which has at least one punch (84), wherein the embossing unit (42) is designed such that the punch (84) penetrates at least partially into the rotor laminated core (46) in the region of the magnet receptacle (22) due to the lifting movement and the magnet (14) is clamped in the magnet receptacle (22) by the material deformation thereby occurring in the edge region of the magnet receptacle (22), and with a control unit (32) which is designed to process an adjustment path variable and a pressure force variable and to control the adjustment unit (48) as a function of the adjustment path variable and the pressure force variable, wherein the adjustment path variable represents the adjustment path by which the plunger (38) and the rotor laminated core (46) move towards one another due to the lifting movement, and the pressure force variable represents the force with which the punch (84) presses onto the rotor laminated core (46). [2] Device according to claim 1, characterized by that the control unit (32) is designed to control the adjustment unit (48) in such a way that the lifting movement is initially carried out as a function of the pressure force magnitude and then, after fulfilling a criterion predetermined for the pressure force magnitude, as a function of the adjustment path magnitude. [3] Device according to claim 2, characterized bythat the criterion is the achievement of a threshold value specified for the pressure force. [4] Device according to one of the preceding claims, characterized by that the receptacle (44) is designed as a further embossing unit. [5] Device according to one of the preceding claims, characterized by that the adjusting unit (48) is designed to move the plunger (38). [6] Device according to claim 5, characterized by that the device (28) has a displacement sensor (54) which is designed to detect the adjustment path which the plunger (38) travels due to the lifting movement. [7] Device according to one of the preceding claims, characterized bythat the embossing unit (42) is designed such that the punch (84) is initially hidden in the embossing unit (42) and only after the embossing unit (42) is in contact with the rotor laminated core (46) due to the lifting movement does it emerge at least partially from the embossing unit (42). [8] Device according to one of the preceding claims, characterized by that the embossing unit (42) has at least one spring (80). [9] Device according to one of the preceding claims, characterized by that the embossing unit (42) has at least one force sensor (86) operatively connected to the stamp (84). [10] Embossing unit, which is designed to fix at least one magnet (14) in a magnet holder (22) of a rotor core (46) of a rotor (10) of an electrical machine, with a receiving element (58) which is designed to fasten the embossing unit (42) to a plunger (38) or to a receptacle (44), a stamp holding element (62) on which at least one stamp (84) is arranged, a contact element (68) which is movably connected to the punch holding element (62) via at least one guide (70), wherein the contact element (68) has an opening (92) through which the punch (84) can pass at least partially, and with at least one spring (80) arranged between the punch holding element (62) and the contact element (68), which spring keeps the punch holding element (62) and the contact element (68) spaced apart from one another. [11] Rotor core for a rotor (10) of an electrical machine, in which at least one magnet (14) is fastened in a magnet holder (22) using a device (28) according to one of claims 1 to 8. [12] Electrical machine comprising a rotor core according to claim 11. [13] Method for fastening at least one magnet (14) in a magnet receptacle (22) of a rotor core (12) of a rotor (10) of an electrical machine, comprising the steps: - arranging an embossing unit (42) on a ram (38), wherein the embossing unit (42) has at least one punch (84), - arranging the rotor core (46) on a holder (44), - Inserting the at least one magnet (14) into the magnet holder (22), - processing an adjustment path variable and a pressure force variable in a control unit (32), wherein the adjustment path variable represents the adjustment path by which the plunger (38) and the rotor core (46) move towards each other due to a lifting movement, and wherein the pressure force variable represents the force with which the plunger (84) presses on the rotor core (46), - Controlling an adjustment unit (48) as a function of the adjustment path size and the pressure force size to carry out the lifting movement, so that the punch (84) penetrates at least partially into the rotor laminated core (46) in the region of the magnet holder (22) due to the lifting movement and the magnet (14) is clamped in the magnet holder (22) by the material deformation thereby occurring in the edge region of the magnet holder (22).

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