Solid rotor core, rotor assembly and motor

Abstract

The invention provides a solid rotor iron core, a rotor assembly and a motor, the solid rotor iron core comprises an iron core body, the outer circumferential wall of the iron core body is provided with a plurality of annular grooves arranged at intervals along the axial direction of the iron core body, the depth of each annular groove is b, the depth b of a fundamental wave magnetic flux generated in the operation process of a motor applying the iron core body into the outer circumferential wall of the iron core body is larger than or equal to 7% and smaller than 7%. According to the solid rotor iron core, a harmonic eddy current loop is effectively cut off on the outer circumferential wall of the iron core body while closed-loop flow of fundamental wave eddy current in the iron core body is not hindered, so that the harmonic eddy current loss of the solid rotor iron core is greatly reduced, the efficiency and mechanical characteristics of a solid rotor motor are improved, and the service life of the solid rotor motor is prolonged. And popularization and application of the solid rotor iron core in the industry are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of motor design, and in particular relates to a solid rotor core, a rotor assembly and a motor. Background Art

[0002] The working principle of the solid rotor induction motor is the same as that of the ordinary induction motor. When the current is passed through the multi-phase winding of the motor stator, a synthetic rotating magnetic field is generated, and an induced electromotive force and current are generated in the solid rotor. The interaction generates electromagnetic force and electromagnetic torque, which causes the rotor to rotate and converts electrical energy into mechanical energy. The stator structure of the solid rotor induction motor is the same as that of the ordinary induction motor. The rotor is a solid ferromagnetic cylinder, which is both the core part of the magnetic circuit and the winding of the circuit. The two are integrated into one, which is the key difference between the solid rotor induction motor and the ordinary induction motor.

[0003] Solid rotors have a simple structure, high mechanical strength and balance, and are suitable for frequent heavy-load starting or long-term operation in braking conditions. However, the disadvantages of solid rotors are also obvious, which greatly affects the application and development of solid rotors. On the one hand, the large rotor loss causes the motor efficiency to be too low, which makes the mechanical characteristics of the solid rotor motor softer and the rated working state slip larger; on the other hand, the depth of the harmonic magnetic flux penetrating into the rotor surface is small, but the eddy current loss caused by the harmonic magnetic flux is large, which leads to low efficiency of the motor, seriously affecting the promotion and application of this type of motor.

[0004] The present invention is proposed to at least partially solve the aforementioned deficiencies in the prior art. Summary of the invention

[0005] Therefore, the present invention provides a solid rotor core, a rotor assembly and a motor, which can solve the technical problem that the solid rotor core in the prior art has large eddy current losses caused by harmonic magnetic flux, resulting in low efficiency of the motor, which seriously affects the promotion and application of this type of motor.

[0006] In order to solve the above problems, the present invention provides a solid rotor core, including a core body, wherein the outer circumferential wall of the core body is provided with a plurality of annular grooves spaced along its axial direction, the depth of the annular grooves is b, and the depth of the fundamental wave magnetic flux generated in the motor used in the core body during operation penetrating into the outer circumferential wall of the core body is △, 7% △≤b<△.

[0007] In some embodiments, Among them, ρ is the rotor resistivity, s is the slip rate, μ0 is the magnetic permeability of the vacuum material, μ1 is the magnetic permeability of the rotor core material, and ω is the power supply angular frequency.

[0008] In some embodiments, the width of each annular groove is a, 0<a<b.

[0009] In some embodiments, the core body is further configured with a plurality of ventilation holes penetrating through both axial ends thereof.

[0010] The present invention further provides a rotor assembly, comprising the above-mentioned solid rotor core, wherein a rotating shaft is inserted into the rotating shaft hole of the solid rotor core.

[0011] In some embodiments, the rotating shaft and the rotating shaft hole are interference fit.

[0012] In some embodiments, conductive and non-magnetic end rings are respectively provided at both ends of the core body, and the radial ring width of the conductive and non-magnetic end rings is c, and c>△.

[0013] In some embodiments, when ventilation holes are configured on the core body, the inner ring wall of the conductive and non-magnetic end ring is located radially outside each of the ventilation holes.

[0014] In some embodiments, the conductive and non-magnetic end rings are welded to the core body.

[0015] The present invention also provides a motor, comprising the above-mentioned rotor assembly.

[0016] A solid rotor core, a rotor assembly and a motor provided by the present invention have the following beneficial effects:

[0017] By providing an annular groove arranged along the circumferential direction on the outer circumferential wall of the core body, and limiting the depth b of the annular groove, the depth b of the annular groove is not greater than the penetration depth of the fundamental magnetic flux, i.e., the aforementioned △, and not less than the penetration depth area of ​​the harmonic magnetic flux, i.e., the aforementioned 7% △, so as to effectively cut off the harmonic eddy current circuit on the outer circumferential wall of the core body without hindering the closed-loop flow of the fundamental eddy current in the core body. In this way, the harmonic eddy current loss (i.e., the additional loss) of the solid rotor core is greatly reduced, which improves the efficiency and mechanical properties of the solid rotor motor (i.e., overcomes the disadvantage of the soft mechanical properties of the solid rotor motor in the prior art), which is conducive to the promotion and application of the solid rotor core in the industry;

[0018] a<b can minimize the adverse effects on the stator-rotor air gap width and ensure that the magnetic flux density of the radial air gap is at a high level;

[0019] Conductive and non-magnetic end rings are respectively arranged at the two axial ends of the core body, so that the reactance at the ends of the core body is greatly reduced, which is equivalent to reducing the end coefficient, thereby reducing the impedance of the solid rotor, improving the power density and force energy index of the motor, and making c>△ able to ensure that most of the eddy currents generated by the fundamental wave magnetic flux of the solid rotor are closed through the conductive and non-magnetic end rings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0021] Figure 1 1 is a schematic diagram of the three-dimensional structure of a solid rotor core according to an embodiment of the present invention (partial cross-section);

[0022] Figure 2 is a schematic diagram of the three-dimensional structure of a rotor assembly according to an embodiment of the present invention;

[0023] Figure 3 yes Figure 2 Side view of

[0024] Figure 4 yes Figure 3 Left view of;

[0025] Figure 5 is a schematic diagram of a simulation of a flow path of harmonic eddy currents in a solid rotor core according to an embodiment of the present invention;

[0026] Figure 6 is a schematic diagram of a simulation of a flow path of a fundamental wave eddy current in a solid rotor core according to an embodiment of the present invention;

[0027] Figure 7 is a schematic diagram of the three-dimensional structure of a rotor assembly according to another embodiment of the present invention;

[0028] Figure 8 is a schematic diagram of the three-dimensional structure of a motor according to an embodiment of the present invention;

[0029] Fig. 9 yes Figure 8 A schematic diagram of a three-dimensional structure of a motor after partial sectioning;

[0030] Fig.10 When a<b, the simulation diagram of the air gap flux density in the stator and rotor air gap shows that the maximum value of the air gap flux density is 0.5610T;

[0031] Fig.11 When a>b, the simulation diagram of the air gap magnetic flux in the stator and rotor air gap shows that the maximum value of the air gap magnetic flux is 0.4538T.

[0032] The accompanying drawings are marked as follows:

[0033] 1. Core body; 11. Ring groove; 12. Ventilation hole; 13. Shaft hole; 2. Shaft; 3. Conductive and non-magnetic end rings; 4. Stator assembly; 41. Stator core; 42. Stator winding; 5. End cover; 51. Threaded fasteners; 6. Bearings. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90° or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0038] See also Figure 1 and Fig.11As shown, according to an embodiment of the present invention, a solid rotor core is provided, including a core body 1 (made of ferromagnetic material), and a plurality of annular grooves 11 are arranged along the axial direction thereof on the outer circumferential wall of the core body 1, and the depth of the annular grooves 11 is b, and the depth of the fundamental wave magnetic flux generated in the motor used in the core body 1 during operation penetrating into the outer circumferential wall of the core body 1 is △, 7%△≤b<△, it can be understood that the aforementioned depth △ is objectively a relatively determined parameter after the specifications and models of the motor used in the core body 1 are determined, and according to research, because the total harmonic distortion rate of the total harmonic content accounts for the fundamental wave content is generally less than 7%, when b is not less than 7%△, most of the harmonic eddy currents can be effectively cut off.

[0039] In this technical solution, an annular groove 11 is arranged on the outer circumferential wall of the core body 1 along the circumferential direction thereof, and the depth b of the annular groove 11 is limited so that the depth b of the annular groove 11 is not greater than the fundamental magnetic flux penetration depth, i.e., the aforementioned △, and is not less than the harmonic magnetic flux penetration depth area, i.e., the aforementioned 7% △, thereby achieving effective cutting off of the harmonic eddy current circuit on the outer circumferential wall of the core body 1 while not hindering the closed-loop flow of the fundamental eddy current in the core body 1. In this way, the harmonic eddy current loss (i.e., additional loss) of the solid rotor core is greatly reduced, which improves the efficiency and mechanical properties of the solid rotor motor (i.e., overcomes the deficiency of the soft mechanical properties of the solid rotor motor in the prior art), which is conducive to the promotion and application of the solid rotor core in the industry.

[0040] In a preferred embodiment, the annular grooves 11 are evenly spaced apart along the axial direction of the core body 1 , so that the machining process of forming the annular grooves 11 on the outer circumferential wall of the core body 1 by machining can be simplified.

[0041] The above △ can be obtained by finite element simulation or according to the formula The preferred method is to use the formula It can be obtained, where ρ is the rotor resistivity, in Ω·m; s is the slip rate, in percentage and dimensionless; μ0 is the magnetic permeability of the vacuum material, in H / m; μ1 is the magnetic permeability of the rotor core material, in H / m; ω is the power supply angular frequency, in rad / s. In this way, after the material selection of the rotor core and the motor design performance are clarified, the design value range of the groove depth of the annular groove 11 can be further clarified through the above formula, thereby simplifying the selection process of the design parameters of the annular groove 11 for a specific rotor core.

[0042] Specifically, when s=1, that is, the penetration depth △ value is the smallest during startup, and when running at a small slip rate, the △ value is larger. For the fundamental magnetic flux (magnetic field), since the penetration depth of the magnetic flux is larger, most of the fundamental magnetic flux will pass through the convex portion between two adjacent annular grooves 11 and penetrate into the inner side of the annular groove 11, ensuring that the additional loss caused by the harmonic eddy current is reduced while the effective output force energy index of the motor is not affected, thereby improving the efficiency of the motor.

[0043] In a specific embodiment, b has a value ranging from 0.01 to 0.015 cm.

[0044] In some embodiments, the width of each annular groove 11 is a, 0<a<b, that is, the axial width of each annular groove 11 should be smaller than its depth, so as to minimize the adverse effect on the width of the stator and rotor air gap. If a>b, it is equivalent to a relative increase in the radial air gap between the stator and rotor of the motor. The air gap is the core of the motor energy conversion. The larger the air gap, the lower the motor efficiency. For example, the simulation comparison data of a certain motor, see Fig.10 and Fig.11 As shown, when a<b, the maximum radial air gap magnetic flux density is a higher value of 0.5610T, while when a>b, the maximum radial air gap magnetic flux density is a lower value of 0.4538T.

[0045] In some embodiments, the core body 1 is further configured with a plurality of ventilation holes 12 penetrating through both axial ends thereof, so as to effectively cool and dissipate the heat of the core body 1 during operation of the core body 1 and prevent excessive temperature rise of the motor.

[0046] See Figures 2 to 7 As shown, according to an embodiment of the present invention, a rotor assembly is further provided, comprising the above-mentioned solid rotor core, wherein a rotating shaft 2 is inserted into the rotating shaft hole 13 of the solid rotor core to output torque externally. In a specific embodiment, the rotating shaft 2 and the rotating shaft hole 13 are interference-fitted, and the interference-fitting method is used to achieve the matching between the rotating shaft 2 and the rotating shaft hole 13, and the process is mature and relatively convenient to implement.

[0047] In some embodiments, conductive and non-magnetic end rings 3 are respectively provided at both ends of the core body 1, and the radial ring width of the conductive and non-magnetic end rings 3 is c, c>△. Specifically, the material of the conductive and non-magnetic end rings 3 can be a good conductor of non-ferromagnetic material, such as copper, aluminum, gold, silver, etc., and copper or aluminum can be used based on cost considerations.

[0048] In this technical solution, conductive non-magnetic end rings 3 are respectively arranged at the two axial ends of the core body 1, so that the reactance at the ends of the core body 1 is greatly reduced, which is equivalent to a reduction in the end coefficient, thereby reducing the impedance of the solid rotor, improving the power density and force energy index of the motor, and making c>△ able to ensure that most of the eddy currents generated by the fundamental wave magnetic flux of the solid rotor are closed through the conductive non-magnetic end rings 3.

[0049] When ventilation holes 12 are constructed on the core body 1, the inner ring wall of the conductive non-magnetic end ring 3 is located radially outside each of the ventilation holes 12. This can reduce the difficulty of structural design of the conductive non-magnetic end ring 3 and thus reduce manufacturing costs. That is, there is no need to set and process the structure corresponding to the ventilation holes 12 thereon.

[0050] In a preferred embodiment, the conductive non-magnetic end ring 3 is welded to the core body 1, so that there is good electrical contact between the conductive non-magnetic end ring 3 and the core body 1, thereby ensuring the smooth flow of fundamental eddy current and improving the structural installation reliability of the rotor core. In a specific embodiment, the conductive non-magnetic end ring 3 and the core body 1 are connected by fusion welding.

[0051] The aforementioned solid rotor core can be manufactured by machining or die-casting, and the aforementioned conductive and non-magnetic end rings 3 can also be manufactured by machining or die-casting.

[0052] According to an embodiment of the present invention, there is also provided a motor, comprising the above-mentioned rotor assembly. Figure 8 and Fig. 9 As shown, the motor further includes a stator assembly 4 and end caps 5 at both ends of the stator assembly 4. The stator assembly 4 includes a stator core 41 (which is formed by pressing a plurality of silicon steel sheets) and a stator winding 42 wound on the stator teeth of the stator core 41. The outer side of the stator core 41 is coated with an insulating layer, and the stator winding 42 is wound on the outer side of the insulating layer. The stator assembly 4 is sleeved on the outer side of the rotor assembly via the stator core 41. The two ends of the rotating shaft 2 in the rotor assembly are supported on the two end caps 5 by bearings 6. The end caps 5 at both ends form an axial clamping on the stator core 41 via threaded fasteners 51. When current is passed through the stator winding 42, a synthetic rotating magnetic field is generated, and an induced electromotive force and current are generated in the solid rotor core. The interaction generates electromagnetic force and electromagnetic torque, so that the rotor assembly rotates.

[0053] The assembly process of the motor of the present invention is described in detail below:

[0054] Step 1: using a special stamping die to laminate silicon steel sheets with excellent magnetic conductivity into a specific stator core (i.e., the aforementioned stator core 41, the same below), and then plastic-coating the stator core for insulation, and then winding a stator winding with a specific number of turns (i.e., the aforementioned stator winding 42, the same below) onto the stator core insulation material layer, the stator winding material is preferably enameled copper wire or enameled aluminum wire, and the stator is manufactured;

[0055] Step 2: Use a dedicated die-casting mold to die-cast a solid rotor core of a specific shape and size, or use a CNC machine tool to fine-turn a solid rotor core of a specific shape (that is, the aforementioned solid rotor core, the same below). The solid rotor core material is preferably a ferromagnetic material with excellent magnetic conductivity;

[0056] Step 3: Use a special die-casting mold to die-cast an end ring of a specific shape and size (i.e., the conductive and non-magnetic end ring 3 mentioned above, the same below), and then weld the core body 1 to the end ring. The end ring and the rotor core should have good electrical contact and a certain mechanical strength. The end ring material is preferably a non-magnetic material with excellent conductive properties, such as aluminum, copper, etc.

[0057] Step 4: Use a hydraulic press to press the shaft (i.e. the shaft 2 mentioned above, the same below) into the solid rotor shaft hole (i.e. the shaft hole 13 mentioned above) to complete the manufacture of the rotor assembly;

[0058] Step 5: Assemble and tighten the stator assembly, rotor assembly, end cover, fastening screws (i.e. the aforementioned threaded fasteners 51), bearings and other components in a specific order to complete the manufacture of the solid rotor motor.

[0059] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A solid rotor core, characterized in that: The invention comprises an iron core body (1), wherein the outer circumferential wall of the iron core body (1) is provided with a plurality of annular grooves (11) arranged at intervals along the axial direction thereof, the depth of the annular grooves (11) being b, the depth of the fundamental wave magnetic flux generated in the motor used in the iron core body (1) during operation penetrating into the outer circumferential wall of the iron core body (1) being △, and 7% △≤b<△.

2. The solid rotor core according to claim 1, characterized in that: Among them, ρ is the rotor resistivity, s is the slip rate, μ0 is the magnetic permeability of the vacuum material, μ1 is the magnetic permeability of the rotor core material, and ω is the power supply angular frequency.

3. The solid rotor core according to claim 1, characterized in that: The groove width of each annular groove (11) is a, 0<a<b.

4. The solid rotor core according to claim 3, characterized in that: The iron core body (1) is also provided with a plurality of ventilation holes (12) penetrating through both axial ends thereof.

5. A rotor assembly, characterized in that: It comprises the solid rotor core according to any one of claims 1 to 4, wherein a rotating shaft (2) is inserted into a rotating shaft hole (13) of the solid rotor core.

6. The rotor assembly according to claim 5, characterized in that The rotating shaft (2) and the rotating shaft hole (13) are interference fit.

7. The rotor assembly according to claim 5, characterized in that: Both ends of the core body (1) are respectively provided with conductive and non-magnetic end rings (3), and the radial ring width of the conductive and non-magnetic end rings (3) is c, where c>Δ.

8. The rotor assembly according to claim 7, characterized in that When ventilation holes (12) are configured on the core body (1), the inner ring wall of the conductive and non-magnetic end ring (3) is located radially outside each ventilation hole (12).

9. The rotor assembly according to claim 7, characterized in that: The conductive and non-magnetic end ring (3) is welded to the iron core body (1).

10. A motor, characterized in that: A rotor assembly comprising any one of claims 5 to 9.

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