Electric machine with a rotor and a short-circuit cage

Abstract

The invention relates to an electric machine having a rotor and a short-circuit cage, wherein the short-circuit cage has two mutually axially spaced rings which are connected to one another by bars, wherein the rotor has axially through-going notches for accommodating the bars, wherein the notches are mutually spaced in the circumferential direction, wherein the rotor has axially grooves which open radially outwards, wherein the radial distance area covered by the axially grooves comprises the radial distance area covered by the bars.

Description

Technical Field

[0001] This invention relates to an electric motor having a rotor and a short-circuit cage / squirrel cage winding. Background Technology

[0002] It is generally known that motors with short-circuit cages can operate as asynchronous motors. Summary of the Invention

[0003] Therefore, the object of the present invention is to improve the motor.

[0004] According to the invention, this objective is achieved by a motor according to the features given in claim 1.

[0005] In terms of motors having a rotor and a short-circuit cage, an important feature of the present invention is that the short-circuit cage has two axially spaced rings, particularly along the direction of the rotor's rotation axis, interconnected by bar / cage bar connections, and particularly electrically connected.

[0006] The rotor has an axially penetrating opening for accommodating the rod.

[0007] The openings are spaced apart from each other in the circumferential direction.

[0008] The rotor has an axial groove that opens radially outward.

[0009] The radial distance region covered by the axial groove includes the radial distance region covered by the bar.

[0010] The advantage here is that it is possible to achieve motor operation in a simple combination, acting as both an asynchronous motor and a reluctance motor. The motor is thus improved to enable advantageous starting and continuous operation synchronized with the frequency of the rotating field generated by the motor's stator. Furthermore, it can be manufactured very simply, as only axial slots need to be milled into the rotor of the asynchronous motor to enable reluctance operation.

[0011] In an advantageous design, the ring, particularly a circular ring, has its ring axis oriented coaxially with the rotor's rotation axis. This has the advantage of aligning the short-circuit cage coaxially with the rotor shaft.

[0012] In an advantageous design, the axial groove has a zero helix angle. The advantage here is that reluctance operation can be implemented in parallel with asynchronous operation.

[0013] In an advantageous design, the axial groove has a first helix angle.

[0014] The bar has a second helix angle, which is different from the first helix angle.

[0015] Specifically, the first helix angle is zero, and the second helix angle has a value between 5° and 30°. The advantage here is that asynchronous operation produces a different polarization than reluctance operation, thus resulting in a reduction in overall polarization.

[0016] In an advantageous design, the range of circumferential angles covered by the corresponding axial grooves at their respective axial positions is independent of the axial position. The advantage here is that the axial grooves extend only in the axial direction and thus, unlike the bars of the short-circuit cage, cause a different pole positioning, thereby reducing the amplitude of the superposition of positioning torque fluctuations during motor rotation.

[0017] In an advantageous design, the axial groove has a cross-section independent of its axial position. The advantage here is that the axial groove can be easily manufactured by allowing a milling tool to move along the rotor in the axial direction.

[0018] In an advantageous design, the circumferential angle range covered by the corresponding axial slot at the corresponding axial position is numerically larger than the range covered by the corresponding bar in the circumferential direction, especially at least three times larger. The advantage here is that, particularly at the synchronous speed of the motor, the effect of the corresponding slot can be greater than that of a single bar, because the slot width results in a reluctance pole of a correspondingly defined size.

[0019] In one advantageous design, the corresponding ring is fixed to the rotor by means of a bayonet connection.

[0020] Specifically, the method is as follows: the ring has an elongated hole extending in the circumferential direction, a screw screwed into an axially threaded hole of the rotor passes through the elongated hole, and the screw head presses the ring against the end of the bar. The axial wall thickness of the ring increases either as the circumferential angle increases or decreases in the edge region of the elongated hole. The advantage here is that a simple yet reliable fixation is achieved, which enables load-bearing contact / connection.

[0021] In an advantageous design, the openings are regularly spaced apart in the circumferential direction in the respective circumferential corner regions that are not interrupted by axial grooves. The advantage here is that the short-circuit cage has bars that are regularly spaced apart in the circumferential direction, especially in the regions not interrupted by axial grooves.

[0022] In an advantageous design, the rotor material has a higher permeability than the rotor shaft material. This has the advantage of generating a sufficiently strong magnetoresistance effect. In particular, the rotor material contains iron and silicon and / or contains iron silicides.

[0023] In an advantageous design, the axial grooves are regularly spaced apart from each other in the circumferential direction.

[0024] In particular, the number of axial slots is between three and nine. An advantage of this is that synchronous operation of the motor can be achieved through the magnetoresistive effect.

[0025] In an advantageous design, axial slots are arranged axially through / continuously on the rotor. The advantage here is that the maximum possible reluctance effect can be achieved.

[0026] In a favorable design, the rotor is designed as a laminated assembly / laminated core.

[0027] In particular, the rotor is constructed as a stack of single laminations / single plates, each lamination being manufactured as a stamped part. The laminations are welded together and / or pressed together by means of tie rods axially extending through the stack.

[0028] In particular, the stacking direction is parallel to the axial direction. An advantage here is that despite the presence of a rotating field, especially an alternating magnetic field, minimal losses are generated. The stacking direction is parallel to the axial direction. Electrical steel sheets or silicon steel sheets, especially iron-containing silicide metal plates, are preferably used as the stacked sheets.

[0029] By casting openings with material, particularly aluminum or copper, the stacked sheets are mechanically stabilized after the material cools, making it possible to introduce them into the grooves via milling.

[0030] In an advantageous design, the first bar of the short-circuit cage connects the two rings to each other, and the other bars end blindly in their respective slots, especially after the slots are introduced into the bar-stabilized laminations of the rotor by milling. The advantage here is that simple manufacturing is achieved by first pouring material into the opening and then milling the slots.

[0031] Other advantages arise from the dependent claims. The invention is not limited to the combination of features of the claims. For those skilled in the art, particularly for purposes presented and / or by comparison with the prior art, other meaningful combinations of claims and / or individual claim features and / or specification features and / or drawing features are possible. Attached Figure Description

[0032] The invention will now be explained in detail with the aid of schematic diagrams.

[0033] exist Figure 1 The motor according to the invention is shown in an exploded perspective view.

[0034] exist Figure 2 The motor is shown in a slanted view.

[0035] exist Figure 3 The image shows a perspective view of the rotor mounted on rotor shaft 2.

[0036] exist Figure 4 The short-circuit cage is shown in a slanted view.

[0037] exist Figure 5 The oblique view in the middle shows the rotor without the short-circuit cage.

[0038] exist Figure 6 The rotor with a short-circuit cage is shown in a perspective view.

[0039] exist Figure 7 The front view of the rotor is shown in the image.

[0040] List of reference numerals in the attached diagram:

[0041] 1. Stator housing

[0042] 2 Rotor shaft

[0043] 3. Bearing cover

[0044] 4 Bearing flange

[0045] 5. Fans

[0046] 6. Fan cover

[0047] 7 rings

[0048] 8. Rotors, especially rotors with polar regions

[0049] 30 slots

[0050] 50 Cavities in the bars of the short-circuit cage Detailed Implementation

[0051] As shown in the figure, the motor has a stator housing 1, on the outside of which heat sinks are formed and a junction box is provided.

[0052] The bearing cover 3 and the bearing flange 4 are connected to the stator housing 1, wherein the stator housing 1 is arranged between the bearing cover 3 and the bearing flange 4.

[0053] The rotor shaft 2 is supported by a first bearing housed in the bearing cover 3 and a second bearing housed in the bearing flange 4. On the side of the bearing cover 3 opposite to the stator housing 1, the fan 5 is pushed onto the rotor shaft 2 and is connected to the rotor shaft in a non-rotational manner.

[0054] The fan cover 6 surrounds the fan 5 and is fixed to the bearing cover 3.

[0055] The rotor 8, preferably formed in an annular shape, is pushed onto the rotor shaft 2 and connected to the rotor shaft 2, especially in a force-locking manner.

[0056] The rotor 8 is made of a material with a higher magnetic permeability than the rotor shaft 2. Preferably, the rotor shaft 2 is made of carburized steel / surface-hardened steel.

[0057] The rotor 8 has axially extending openings, particularly cavities 50, which are configured to accommodate the bars of the short-circuit cage. For this purpose, liquid aluminum-containing or liquid copper-containing material is injected into the openings, thereby manufacturing the bars after the material cools.

[0058] Ring 7 is pressed against rotor 8 on both axial sides. The ring is in electrical contact with the bars, especially the axial ends of the bars, thus completing the short-circuit cage. For this purpose, the ring has elongated holes extending in the circumferential direction through which screws pass. The corresponding screw heads, in a bayonet-type connection, increasingly press the ring 7 axially against rotor 8 as the ring 7 rotates relative to rotor 8, because the wall thickness of the area of ​​ring 7 accommodating the elongated holes increases in the circumferential direction.

[0059] The openings are implemented with a helical angle. Therefore, the openings extend increasingly in the circumferential direction in the axial direction. Here, these openings are always positioned at the same radial distance.

[0060] The axially oriented slots 30 without helix angle are radially outwardly opened and / or machined into the rotor 8, wherein the slots 30 are arranged at a constant radial distance and always remain at the same circumferential angular position in the axial direction, i.e., not increasingly extending in the circumferential direction.

[0061] The slots 30 are spaced apart from each other in the circumferential direction, and in particular, are spaced evenly. Preferably, four slots 30 are provided on the outer periphery of the rotor 8.

[0062] By introducing the axially oriented slots 30 that are radially external to the environment on the rotor 8, some openings, along with the injected material, lead to the corresponding slots 30. This means that the corresponding bars terminate blind-end in the corresponding slots, thus preventing current from flowing from one ring to another. This is because the slots 30 are introduced into the rotor 8 only after the material has been injected and cooled.

[0063] The originally cylindrical rotor 8 has a region reserved in the circumferential direction between the slots 30, which serves as a pole region capable of reluctance operation. Because the reserved region protrudes radially from the slots and is oriented to minimize the magnetic field lines, a torque is generated during reluctance operation, achieving a rotational motion of the rotor as synchronized as possible within the rotating field generated by the stator.

[0064] Additionally, rotor 8 also has a short-circuit cage, which enables it to operate as an asynchronous motor. Overall, this allows for improved starting of the motor, which operates synchronously in a rotating field after startup.

[0065] The circumferential width of the groove is less than the circumferential spacing between two adjacent circumferentially adjacent grooves.

[0066] Preferably, the rotor 8 is made of silicon steel because iron silicides have very high magnetic permeability. In this way, the rotor 8 can have a higher magnetic permeability than the rotor shaft 2.

Claims

1. An electric motor having a rotor and a short-circuit cage, The short-circuit cage has two axially spaced rings, that is, rings spaced apart from each other along the rotation axis of the rotor, and these two rings are electrically connected to each other by a bar. The rotor has an axially through opening for accommodating the rods. The openings are spaced apart from each other in the circumferential direction. Its features are, The rotor has axial grooves that open radially outward. The radial distance region covered by the axial groove includes the radial distance region covered by the bar. The axial groove has a first helix angle, and the bar has a second helix angle, which is different from the first helix angle. After the axial slots are introduced into the rotor’s bar-stabilized laminations by means of milling, the first bar of the short-circuit cage electrically connects the two rings to each other, while the other bars terminate blindly in their respective axial slots.

2. The motor according to claim 1, Its features are, The ring axis is oriented coaxially with the rotation axis of the rotor.

3. The motor according to claim 1 or 2, Its features are, The axial groove has a first helix angle of zero.

4. The motor according to claim 1 or 2, Its features are, The second helix angle has a value between 5° and 30°.

5. The motor according to claim 1 or 2, Its features are, The range of circumferential angles covered by the corresponding axial groove at the corresponding axial position is independent of the axial position.

6. The motor according to claim 1 or 2, Its features are, The axial groove has a cross-section that is independent of its axial position.

7. The motor according to claim 1 or 2, Its features are, The range of circumferential angles covered by the corresponding axial groove at the corresponding axial position is numerically greater than the range covered by the corresponding bar in the circumferential direction, and the range of circumferential angles covered by the corresponding axial groove at the corresponding axial position is numerically at least three times larger than the range covered by the corresponding bar in the circumferential direction.

8. The motor according to claim 1 or 2, Its features are, The corresponding rings are fixed to the rotor by means of bayonet connections. The method is as follows: the ring has an elongated hole extending in the circumferential direction, a screw screwed into the axially pointing threaded hole of the rotor passes through the elongated hole, the screw head presses the ring against the end of the bar, and the axial wall thickness of the ring increases with the increase of the circumferential angle or increases with the decrease of the circumferential angle in the edge region of the elongated hole.

9. The motor according to claim 1 or 2, Its features are, In the corresponding circumferential angular region that is not interrupted by the axial groove, the openings are regularly spaced apart from each other in the circumferential direction.

10. The motor according to claim 1 or 2, Its features are, The rotor material has a higher magnetic permeability than the rotor shaft material. The rotor is made of iron and silicon and / or iron silicides.

11. The motor according to claim 1 or 2, Its features are, The axial grooves are regularly spaced apart from each other in the circumferential direction. The number of axial grooves is between three and nine.

12. The motor according to claim 1 or 2, Its features are, The axial groove is axially through the rotor.

13. The motor according to claim 1 or 2, Its features are, The rotor is configured as a laminated assembly. The rotor is constructed as a stack of single laminations, each of which is manufactured as a stamped part. The single laminations are welded together and / or pressed together by means of tie rods extending axially through the stack. The stacking direction is parallel to the axial direction orientation.

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