Rotating electric machines

Abstract

To provide a rotary electric machine with reduced windage.SOLUTION: A rotary electric machine 1 with a gap between a rotor 20 and a stator 10, when the outer radius of the rotor 20 is ri, the inner radius of the stator 10 is ro, the dynamic viscosity coefficient of the fluid in the gap is v, the rotation speed of the rotor 20 is p, and the tolerance is aMAX, the maximum height δMAX of the gap-facing surfaces of the rotor 20 and the stator 10 is determined on the basis of the following formula.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] In rotating electrical machines such as radial gap motors, the rotor and stator face each other in the radial direction of the rotating shaft, forming a gap between them. A fluid, such as air, is present in this gap. By smoothing the rotor and stator surfaces facing the gap, the air resistance can be reduced and windage loss can be suppressed. One method for reducing windage loss is to fill the slot opening grooves in the stator of a rotating electrical machine with a spacer or the like, thereby eliminating surface irregularities (see, for example, Patent Document 1). Because it is difficult to create a cylindrical surface on the inner diameter side of the stator by filling only the slot opening grooves, Patent Document 1 uses a resin spacer formed by injecting and molding resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-133920 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not specifically describe how smooth the rotor and stator surfaces facing the gap should be when smoothing them to suppress windage loss, which makes it unclear how smooth the rotor and stator surfaces facing the gap should be when actually designing.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a rotating electric machine in which the rotor surface and stator surface are specifically designed to suppress windage loss. [Means for solving the problem]

[0006] A rotating electric machine according to one aspect of the present invention is a rotating electric machine that is composed of an inner cylindrical tube and an outer cylindrical tube formed around the same axis, and has a gap between the inner cylindrical tube and the outer cylindrical tube, and the outer radius of the inner cylindrical tube is r i , the inner radius of the cylindrical outer tube is r o , the dynamic viscosity coefficient of the fluid in the gap is v, the rotation speed of the rotating tube of the cylindrical inner tube or the cylindrical outer tube is p, The degree of suppression of windage loss between the cylindrical inner pipe and the cylindrical outer pipe and the maximum height δ of the surface facing the gap MAX The minimum value of the parameter a in the range in which the change in the windage loss relative to the change in the parameter a relating the windage loss and the windage loss is equal to or less than a predetermined value. Let the tolerance be a MAX If so, based on the following formula, Last Large height δ MAX but decision It has been

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[0007] According to a rotating electric machine of one aspect of the present invention, the rotor surface and the stator surface are specifically designed to suppress windage loss. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a rotating electric machine according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged view showing the configuration of part A in FIG. [Figure 3] 1 is a conceptual diagram of a rotating electric machine design device for implementing a rotating electric machine design method. [Figure 4] 10 is a graph showing an example for setting a tolerance level. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0010] The configuration of an example of a rotating electric machine 1 to which the method for designing a rotating electric machine according to this embodiment can be applied will be described using Fig. 1. Fig. 1 is a diagram showing an example of the rotating electric machine 1 according to this embodiment. The rotating electric machine 1 includes a stator 10 around which coils 12 are wound, a rotor 20 on which permanent magnets (not shown) are arranged, and a motor shaft fitted into the iron core of the rotor 20 along an axis X.

[0011] The rotating electric machine 1 of this embodiment is an inner rotor type rotating electric machine in which a cylindrical rotor 20 is disposed on the inner diameter side of a cylindrical stator 10. The rotating electric machine 1 has a double cylindrical pipe structure, and the stator 10 and the rotor 20 are configured to extend around the same axis X in the axial direction of the axis X.

[0012] The rotating electric machine 1 of this embodiment is a radial gap type rotating electric machine 1. That is, a radial gap (space) is formed between the inner diameter side of the stator 10, which is a cylindrical outer tube, and the outer diameter side of the rotor 20, which is a cylindrical inner tube. A fluid such as air inside the rotating electric machine 1 flows through this gap. With this structure, in the rotating electric machine 1, the stator 10 is fixed, and the rotor 20, which is the cylindrical inner tube, rotates about the axis X.

[0013] The stator 10 has slots 11 that accommodate the coils 12. The slots 11 are arranged at equal intervals in the circumferential direction of the stator 10. In this embodiment, the stator 10 has 24 slots 11 formed therein, but the number of slots is not limited to this.

[0014] The detailed configuration of the slot 11 will be described using FIG. 2. FIG. 2 is an enlarged view showing the configuration of portion A in FIG. 1. In this embodiment, the slot 11 has an opening 11a that opens into the inner diameter surface 10a of the stator 10. The opening 11a opens into the inner diameter surface 10a in the circumferential direction of the stator 10 with a predetermined width w and has a predetermined groove depth d. In this embodiment, the groove depth d of the opening 11a refers to the length from the position where it opens into the inner diameter surface 10a to the plate 14. However, if the plate 14 is not required, the height of the side surface 13 of the opening 11a may be considered to be the groove depth d.

[0015] The configuration of an apparatus for implementing the rotating electric machine design method of this embodiment will be described with reference to Figure 3. A rotating electric machine design apparatus 50 has an input unit 51, a computer C that performs design based on information input from the input unit 51, and a display unit 56 that displays the results obtained by the computer C.

[0016] The input unit 51 is an input means such as a keyboard. A user or the like inputs information relating to the stator 10 and rotor 20 of the rotating electric machine 1 to the input unit 51 (input process). Note that the input to the input unit 51 does not have to be manual input by the user, and may be a method in which only data is input from outside. The information input to the input unit 51 is transmitted to the computer C.

[0017] The computer C has a CPU 52 that performs arithmetic processing. The CPU 52 has an arithmetic processing unit 53 that performs arithmetic processing of input information, and a control unit 54 that controls the computer C and each unit connected to the computer C. The computer C has a storage unit 55 that stores programs, input data, etc. The storage unit 55 has memory such as ROM and RAM that serves as a work area for the CPU 52. With this configuration, the CPU 52 and the program stored in the storage unit 55 work together to perform calculations by the arithmetic processing unit 53 (arithmetic processing step). This allows the computer C to realize a rotating electric machine design method, which will be described in detail later. The rotating electric machine design information obtained by the computer C is displayed on the display unit 56 (display step), allowing the user to recognize it.

[0018] Next, a method for designing a rotating electric machine according to this embodiment will be described in detail. In this embodiment, the rotating electric machine design method will be described using the above-described rotating electric machine 1, which is configured with a stator 10 that is a cylindrical outer tube and a rotor 20 that is a cylindrical inner tube formed around the same axis X, as a model.

[0019] In the method for designing a rotating electric machine according to this embodiment, information about the rotating electric machine 1 is input from the input unit 51, and the computer C performs calculations using a program related to the following formula stored in the storage unit 55. As a result, the maximum height δ of the stator 10 and rotor 20 facing the gap is calculated. MAX Design.

[0020] Specifically, the outer radius of the rotor 20 as a cylindrical inner tube is r i [m], the inner radius of the stator 10 as a cylindrical outer tube is r o [m], the dynamic viscosity of the fluid in the gap is v[m 2 / S], the rotation speed of the rotor 20 as a rotating tube is p [min -1 ], the tolerance is a MAX When [-] (described later) is used, the maximum height δ of the stator 10 and the rotor 20 is calculated based on the following formula: MAX Determine the maximum height δ MAX In the case of the stator 10 of this embodiment, is the same as the depth d of the groove of the opening 11a of the slot 11 of the stator 10.

[0021]

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[0022] In the above formula, the maximum height δ is determined by the rotation speed p of the rotor 20. MAX The formula for calculating ρ is changed. In other words, the value is made larger at high rotation speeds than at low rotation speeds. This is because the size of the vortex of the working fluid formed in the gap changes depending on the rotor rotation speed.

[0023] Next, the tolerance a in the above formula MAXThis section explains how to set the tolerance level a. MAX The parameter a that is the basis of this is the degree of windage loss suppression and the maximum height δ of the surface irregularities facing the gap. MAX This is the parameter that relates the

[0024] Figure 4 shows the tolerance level a MAX 4 is a graph showing an example for setting the parameter a and the rate of change of fluid friction torque in the gap R T The values ​​used to calculate this figure are the outer radius r of the rotor 20. i =0.0788[m], inner radius r of stator 10 o =0.081 [m], width w of opening 11a of slot 11 =2.8 [°], number of slots 11 =24.

[0025] As shown in Figure 4, the rate of change of fluid friction torque R T The change in the fluid friction torque, i.e., the change in the windage loss, can be expressed by the parameter a. As shown in the graph in Figure 4, when the value of the parameter a is 100 or more, the rate of change in the fluid friction torque R T If it is recognized that there is almost no change in the tolerance level a MAX is set to 100. Tolerance level a MAX If we set = 100, the maximum height δ of the unevenness on the surface facing the gap MAX can be expressed as in the following table:

[0026] [Table 1]

[0027] In this embodiment, the tolerance a MAX is set to 100, but it is not limited to this. MAX can be set appropriately by the user according to the characteristics and needs of the rotating electrical machine to be designed.

[0028] As described above, according to this embodiment, the tolerance a is calculated using the parameter a. MAX By setting the maximum height δ of the asperities on the surface facing the gap,MAX can be easily calculated. MAX In this method, the rotor rotation speed is set to be different when the rotor rotation speed is low and when the rotor rotation speed is high. Therefore, by designing a rotating electric machine based on this rotating electric machine design method, it is possible to provide a rotating electric machine in which the rotor surface and stator surface are specifically designed to suppress windage loss.

[0029] Furthermore, by designing a rotating electric machine based on the rotating electric machine design method described in this embodiment, the rotor surface and the stator surface of the rotating electric machine can be configured to suppress windage loss. That is, when configuring a rotating electric machine, the unevenness of the surfaces of the stator 10 and the rotor 20 facing the gap is set to a maximum height δ MAX Specifically, the maximum height δ of the unevenness on the surface facing the gap is MAX To achieve this, for example, the shape of the mold used to form the opening 11a of the slot 11 may be adjusted, or a material to fill the opening 11a may be inserted into the opening 11a, but this is not a limitation.

[0030] Furthermore, if the rotating electrical machine design method described in this embodiment is programmed and executed by a computer, a rotating electrical machine capable of suppressing windage loss can be designed using the computer.

[0031] In the above embodiment, an inner rotor type configuration was described as an example of the rotating electric machine 1, but this is not limited thereto, and as long as the rotating electric machine has a double cylindrical tube structure, the above-described rotating electric machine design method can be applied to configure the rotating electric machine. For example, even if the rotating electric machine has an outer rotor type configuration in which the cylindrical outer tube is the rotor and the cylindrical inner tube is the stator, the above-described rotating electric machine design method can be applied to configure the rotating electric machine.

[0032] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0033] 1... rotating electric machine, 10... stator, 10a... inner diameter surface, 11... slot, 11a... opening, 12... coil, 13... side surface, 14... plate, 20... rotor, 50... rotating electric machine design device, 51... input unit, 52... CPU, 53... calculation processing unit, 54... control unit, 55... storage unit, 56... display unit, C... computer

Claims

[Claim 1] A rotating electric machine comprising an inner cylindrical tube and an outer cylindrical tube formed around the same axis, with a gap between the inner cylindrical tube and the outer cylindrical tube, The outer radius of the cylindrical inner tube is r ｉ , the inner radius of the cylindrical outer tube is r ｏ , the dynamic viscosity coefficient of the fluid in the gap is v, the rotation speed of the rotating tube of the cylindrical inner tube or the cylindrical outer tube is p, and a parameter a relating the degree of suppression of windage loss between the cylindrical inner tube and the cylindrical outer tube to the maximum height δ MAX of the surface facing the gap is changed. The parameter a is the minimum value of the parameter a within a range in which the change in the windage loss with respect to the change is equal to or less than a predetermined magnitude. ＭＡＸ In this case, the maximum height δ is calculated based on the following formula: ＭＡＸ has been determined [Equation 1] A rotating electric machine characterized by:

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