Rotor with a squirrel cage winding

Abstract

The invention discloses a rotor (5) of a rotary electric machine (1), wherein the rotor (5) has the following features: - at least one magnetically conductive body having essentially axially extending slots (10) distributed along the circumference, - at least one squirrel cage winding (8) having electrical conductors (7) arranged in the slots (10), which are electrically contacted at both end sides (9) of the rotor (5) by means of assigned short-circuit rings (8), - the magnetically conductive body has a base body (12) and at each end side (9) at least two further additional bodies (11, 28), which are connected to the base body (12) in axial direction, wherein a first additional body (11) is connected in axial direction directly to the end side of the base body (12) and a second additional body and if necessary further additional bodies are connected in axial direction to the first additional body, respectively, - the slots or slot sections (17) are exposed radially in the axial end region of the rotor (5), so that a radial outward movement of the conductors (7) is enabled.

Description

Technical Field

[0001] This invention discloses a rotor having a cage-like armature and an electric motor having such a rotor. Furthermore, this invention discloses a method for manufacturing such a rotor having a cage-like armature. Background Technology

[0002] The rotor of an electric motor, particularly an asynchronous motor, with a cage-type armature, is manufactured at low cost using cast rotor windings. Here, a short-circuit ring abuts against the end of the rotor lamination assembly and is mechanically and electrically fixedly connected to a conductor rod, for example.

[0003] Due to the thermodynamic expansion and / or centrifugal stress of the motor during operation, the short-circuit ring extends radially more than the laminations of the rotor with cast rods. This generates shear stress at the conductor rod-short-circuit ring connection. The level of this shear stress limits the maximum possible speed and maximum permissible temperature of the motor.

[0004] The cap ring on the outer circumference of the short-circuit ring used to achieve higher speeds is unsuitable or only applicable in a limited way, because it cannot avoid shear stresses, for example, that are thermodynamically limited.

[0005] Therefore, cast cage windings can no longer be used when the permissible measurement limits are exceeded.

[0006] Therefore, the squirrel-cage winding, also known as the short-circuit winding, is made of individual introduced rods and brazed or welded short-circuit rings. These windings, based on a manufacturing method, have axial rod margins at the ends of the laminations, which allows for thermodynamic expansion of the short-circuit rings and thus enables higher speeds and / or higher temperatures. The use of cap rings allows for further speed increases in this motor. Summary of the Invention

[0007] Therefore, the object of this invention is to provide a rotor for an electric motor with squirrel-cage windings, which can be easily manufactured and is suitable for relatively high speeds. Furthermore, a corresponding electric motor should also be provided.

[0008] The solution to this objective is achieved through the rotor of a rotary electric motor, wherein the rotor has the following characteristics:

[0009] - At least one magnetic conductor having slots that are substantially axially extended and distributed around the circumference.

[0010] - At least one squirrel-cage winding having electrical conductors arranged in slots, which are electrically contacted at both ends of the rotor by means of assigned short-circuit rings.

[0011] - The magnetic conductor has a base and at least two additional bodies on each end side, the additional bodies being axially connected to the base, wherein a first additional body is directly axially connected to the end side of the base, and a second additional body and, if necessary, additional additional bodies are axially connected to the first additional body.

[0012] - Radially exposed slots or slot sections enable radially outward movement of the conductor in the axial end region of the rotor.

[0013] The solution to this objective is also achieved by a method for manufacturing a rotor of a rotary electric motor with squirrel-cage windings according to the present invention, the method comprising the steps of:

[0014] - Manufacture a magnetic conductor having slots that are substantially axially extended and distributed along the circumference.

[0015] - Manufacture a squirrel-cage winding having electrical conductors arranged in slots, which are electrically contacted at both ends of the rotor by means of short-circuit rings.

[0016] - Material removal is performed axially from the end side of the rotor at the radial outer edge to expose the conductor in this region, thereby enabling radial movement of the conductor.

[0017] The magnetic conductor has a base and at least two additional attachments on each end, which are axially connected to the base. Here, a first attachment is directly axially connected to the end of the base, and a second attachment and, if necessary, additional attachments are axially connected to the first attachment. The first attachment is a disk or disc, which largely matches the contour of the base.

[0018] In order to enable the thermodynamic expansion of the short-circuit ring relative to the lamination assembly during motor operation according to the present invention, the slots, particularly the slots at the ends of the lamination assembly, are designed segment by segment in the first attachment, on the second attachment, and, if necessary, on additional attachments, so that the rod can move radially outward.

[0019] To address this, a slot geometry is provided at the ends of the magnetic conductor, particularly in the second and additional attachments, which is not undercut and therefore has parallel sides or is radially outwardly oriented. In other words, the slot walls have parallel sides or radially extend outwardly to increase the spacing between them.

[0020] In low-pressure casting methods, the groove geometry can be designed to be closed or open. Here, the casting cover is responsible for sealing the radially outward open groove geometry or conductor. Secondary attachments and additional attachments, i.e., the open rod or conductor areas, can be designed in a laminated or solid disc form, having a multi-fold laminate thickness (5 to 20 times). The disc material can also be the same as the laminate material or (electrically) a lower value than the standard.

[0021] In medium-pressure and high-pressure casting methods used to manufacture conductors, a closed groove is required (firstly) based on the manufacturing process. In the case of a closed groove, the rod or conductor is then exposed at the end of the lamination assembly by turning the outer diameter. Therefore, a groove geometry without undercut is also proposed, which allows radial movement based on thermodynamic effects and / or centrifugal force. In other words, the groove walls are designed to be parallel or have a certain angle.

[0022] Because the electric laminations are typically designed to be 0.5 mm or 0.65 mm thick, and in the absence of a first attachment, sections of varying torsion or tearing intensities are generated on the laminations at the end of free expansion.

[0023] According to the invention, this is achieved such that a corresponding axially thicker disk or disc is attached to the base as a first attachment, so that free expansion ends in the homogeneous material of the disk, i.e., the first attachment.

[0024] The area between the short-circuit ring and the first additional body, i.e., the disk, can be designed as a stacked structure and / or even as a solid structure at the end of free expansion. The groove geometry must conform to the above standards in all cases.

[0025] In other words, the second and other attachments can be designed as stacked pieces and can also be designed as solid.

[0026] To further increase the motor speed, a cap ring can be additionally used on the outer circumference of the short-circuit ring. Depending on the desired speed level of the motor, it may have an additional cover, either only in the region of the short-circuit ring or in the region of the radially open slot.

[0027] Therefore, according to the present invention, a low-cost manufacturing method for the cast cage windings for the rotor can now also provide higher speeds for the motor. Here, the short-circuit ring is located directly on the end side of the magnetic conductor. This also reduces the axial leading edge of the rotor, thereby achieving a compact motor.

[0028] In particular, this advantage is particularly relevant for conventionally manufactured copper rotors when using aluminum die casting and centrifugal casting techniques.

[0029] According to the present invention, from now on, the application of casting technology using the design scheme of the groove end according to the present invention results in a conductor or rod with radial movement at the end of the magnetic conductor, so as to allow radial movement based on thermodynamic effects and / or centrifugal force.

[0030] By additionally employing a cap ring, such a rotor can be adapted to higher speed ranges of the motor. Attached Figure Description

[0031] The invention and its alternative designs are described in detail based on the embodiments shown in the principle diagram; as shown herein:

[0032] Figure 1 This shows a partial longitudinal section of the squirrel cage winding.

[0033] Figure 2 This shows a partial cross-section of the squirrel cage winding.

[0034] Figure 3 , Figure 4 This shows another portion of the longitudinal section of the squirrel cage winding.

[0035] Figure 5 The treated partial longitudinal section of the squirrel cage winding is shown.

[0036] Figure 6 This shows a partial cross-section of the squirrel cage winding.

[0037] Figure 7 , Figure 8 This shows the longitudinal section of the motor in principle. Detailed Implementation

[0038] Figure 1 A partial longitudinal section of rotor 5 is shown, which is constructed as a squirrel-cage winding and has a magnetic conductor with slots 10 that extend substantially axially and are distributed circumferentially. The different slot configurations shown there are exemplary and can also be designed in other configurations.

[0039] The magnetic conductor has a base body 12 and multiple additional bodies 11, 28 arranged sequentially along the axial direction.

[0040] A squirrel-cage winding 6 with electrical conductors 7 arranged in slots 10 is provided in the magnetic conductor. The electrical conductors 7 are electrically contacted at both ends 9 of the rotor 5 by means of assigned short-circuit rings 8.

[0041] Here, the conductor 7 in the groove 10 is generated using aluminum die casting or centrifugal casting techniques, or by pre-manufacturing the conductor rod. In casting techniques, the short-circuit ring 8 is generated by casting. In the pre-manufacturing conductor rod, post-construction electrical contact between the conductor rod and the pre-manufacturing short-circuit ring 8 is required, at least at the end.

[0042] Although the squirrel cage winding is theoretically operable in this state, thermal stress and / or centrifugal stress cause (as designed above) harmful shear stress at the connection points of the conductor 7 and short-circuit ring 8 arranged in slot 10 during motor operation.

[0043] The attachments 11 and 28 connected axially to the base 12 are configured as disks in the first attachment 11 and as disks and / or sub-staples in the subsequent attachments 28.

[0044] The rotor 5 can have additional torque composition features besides the squirrel-cage winding 8, such as a design as a reluctance rotor and / or permanent magnet. This then allows the motor 1 to be started directly on the grid without the intermediate circuitry of a converter.

[0045] Preferably, the base 12 is designed in a stacked manner, and the first attachment 11 is connected to the base as a disk along the axial direction. Additional disks and / or sub-stacking groups are then connected to it along the axial direction.

[0046] The conductor 7 has at least one step 19 in the axial direction, which manifests as a cross-sectional enlargement in the first attachment 11 and a further cross-sectional enlargement in the additional attachment 28. This improves stability.

[0047] The short-circuit ring 8 protrudes radially inward on the end side 9 of the last attachment 28 along the axial direction and abuts against the end side 9.

[0048] The shape of the slot 10 in the base 12 can be designed approximately arbitrarily. However, in the addendum 28, according to Figure 2 The groove wall 15 of the groove 10 has parallel sides or is designed as an open groove wall with a slight angle. Therefore, from now on, it is possible to perform radial outward movement of the conductor 7 in the attachment 28 during operation of the motor 1 by turning the radially outer edge from the disc and / or sub-laminate assembly to the conductor 7 according to the invention.

[0049] Figure 3 , Figure 4 The design of the other attachment 28 is different. Firstly, the second attachment 28 is also a disk. Figure 4 The additional component 28 is a sub-stack. Figure 1 The additional component 28 is a disk and sub-laminated assembly. All these embodiments mean that the first component 11 is designed as a disk. Here, the disk corresponds to a multiple (4 to 15 times) the lamination thickness in its axial thickness.

[0050] Crucially, the material removal process during turning ends axially inside the disc of the first attachment 11. The turned section 17 extends axially from the outside of the short-circuit ring 8 into the first attachment 11.

[0051] Therefore, the free expansion or material removal ends in the homogeneous material of the corresponding axially thicker disk or disc, which is attached to the base as a first attachment.

[0052] Material removal along the axial direction is not permitted before this point, because otherwise the material removal may end in the sub-stack, resulting in stacks with varying degrees of torsion or even torn stack segments.

[0053] Therefore, the radial end of conductor 7 is exposed axially in the additional attachment 28 and only partially exposed axially in the first attachment 11.

[0054] Figure 5 It shows that according to Figure 1 The longitudinal section of the squirrel cage winding after processing. Here, starting from the short-circuit ring 8, the tooth tip is machined in the region of the last attachment 28 and part of the slot 10 of the first attachment 11 along the axial direction.

[0055] According to the present invention, this also allows for radial deviation of the short-circuit ring 8 under thermodynamic stress, without generating shear stress at the connection point to the conductor 7.

[0056] By according to Figure 6 The slot shape design in the attachments 28 and 11 allows conductor 7 to move radially.

[0057] according to Figure 7 or Figure 8 Such a machine has axially continuous magnetic conductors for the rotor 5 and the stator 2, or it consists of a sub-base lamination group 26 so that it is also radially cooled.

[0058] Here, the airflow 23 is either diverted by the motor 1 or exists in a closed internal cooling cycle. The airflow 23 is provided by the shaft fan 22 and / or an external fan.

[0059] These sub-basic stacks 26 also form the base 12, where the aforementioned material removal is not performed.

[0060] This invention can also be used for trapezoidal rotors.

Claims

1. A rotor (5) of a rotary electric motor (1), wherein, The rotor (5) has the following characteristics: - At least one magnetic conductor having axially extending grooves (10) distributed circumferentially. - At least one squirrel cage winding having an electrical conductor (7) arranged in the slot (10), the electrical conductor being electrically contacted at both ends (9) of the rotor (5) by means of distributed short-circuit rings (8). - The magnetic conductor has a base (12) and at each of the end sides (9) at least two additional bodies (11, 28) connected axially to the base (12), wherein the base (12) is designed as a laminate and is continuous axially, or the base is composed of sub-base laminate groups (26), wherein a first additional body (11) is directly connected axially to the end side of the base (12), and a second additional body and the additional bodies (28) are respectively connected axially to the first additional body, wherein the first additional body (11) is made of a homogeneous material, and the axial thickness of the first additional body corresponds to a multiple of the laminate thickness. - A slot or slot segment (17) is radially exposed in the axial end region of the rotor (5) to enable radially outward movement of the conductor (7), wherein the radially exposed slot or slot segment (17) is provided at least in the axially external attachment (28) at each of the end sides (9) of the magnetic conductor, and the slot or slot segment is provided only for a predetermined axial segment in the first attachment (11) located directly at the base (12).

2. The rotor (5) of the rotary electric motor (1) according to claim 1, characterized in that, The first attachment (11) is a disk and the other attachment (28) is a disk and / or a sub-staple assembly.

3. The rotor (5) of the rotary electric motor (1) according to claim 1 or 2, characterized in that, The base (12) has a disc at the end side (9) of the base, the disc having a pre-defined axial section with a groove (10) exposed along the axial direction, and the base also has additional discs and / or sub-stacks with exposed grooves.

4. The rotor (5) of the rotary electric motor (1) according to claim 1 or 2, characterized in that, The grooves (10) of the axial sections of the base (12) and the first attachment (11) are either partially open or closed.

5. The rotor (5) of the rotary electric motor (1) according to claim 1 or 2, characterized in that, In addition to the squirrel cage winding, the rotor (5) also has the additional torque-forming features of a synchronous motor, such as the features of forming permanent magnets and / or magnetic reluctance torque.

6. A method for manufacturing a rotor (5) according to claim 1 for a rotary electric motor (1) having a squirrel-cage winding, the method comprising the following steps: - Manufacture a magnetic conductor having axially extending grooves (10) distributed along the circumference, - Manufacture a squirrel cage winding having electrical conductors (7) arranged in the slot (10), the electrical conductors being electrically contacted at both ends (9) of the rotor (5) by means of short-circuit rings (8). - Material removal is performed axially from the end side (9) of the rotor (5) at the radial outer edge to expose the conductor (7) radially in this region, thereby enabling radial mobility of the conductor (7), wherein, The radially exposed groove or groove segment (17) is provided at least in the axially external attachment (28) at each of the end sides (9) of the magnetic conductor, and the groove or groove segment is provided only for a predetermined axial segment in the first attachment (11) directly on the base (12).

7. The method according to claim 6, characterized in that, The magnetic conductor is constructed axially from a base (12) and additional bodies (11, 28).

8. The method according to claim 6 or 7, characterized in that, The conductor (7) of the squirrel cage winding is manufactured by die casting or centrifugal casting.

9. The method according to claim 8, characterized in that, The conductor (7) is manufactured by centrifugal casting by covering the radially open or partially open slots (10) during the manufacturing process.

10. The method according to claim 8, characterized in that, The conductor (7) is manufactured by die casting, wherein all the grooves (10) of the base (12) and the attachments (11, 28) are designed to be closed before removal.

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