Rotor of a rotating electric machine

Abstract

This utility model discloses a rotor for a rotary electric machine. The objective is to reduce the surface pressure acting on the mating surfaces while ensuring the strength of the rotor core when pressing the shaft into the rotor core. The rotor core of the rotary electric machine includes a plurality of elongated holes, which are spaced apart in the circumferential direction, extending along the shaft hole along the circumferential direction of the rotor core and along the central axis of the shaft hole along the axial direction of the rotor core. The inner circumferential surface of the elongated holes includes: a pair of first surfaces extending along the circumferential direction and radially opposite the rotor core; two second surfaces forming the circumferential ends of the elongated holes; and four third surfaces, each having a radius of curvature larger than that of the surface contained in the second surfaces and continuous with the corresponding first and second surfaces.

Description

Technical Field

[0001] This utility model relates to a rotor of a rotary electric motor, which includes an annular rotor core and a shaft pressed into a shaft hole in the rotor core. Background Technology

[0002] Conventionally, a rotor core for a rotating electric machine is known, comprising: a key formed on the inner circumferential surface of a shaft hole into which a rotor shaft is pressed, protruding toward a central axis; and recesses provided on both circumferential sides of the key and recessed radially outward to form non-contact inner circumferential contact surfaces with the pressed rotor shaft (for example, see Patent Document 1). In this rotor core, a plurality of elongated holes are perforated circumferentially, including portions that separate radially outward from the contact end, which serves as a switching portion between the inner circumferential contact surface and the recess, by a predetermined wall thickness. Each elongated hole extends toward the key side by a predetermined first angle relative to a reference line intersecting the central axis and the contact end, and extends toward the side opposite to the key side by a predetermined second angle or more. Thus, in a rotor core including these elongated holes, the contact end and the adjacent inner circumferential contact surface can be released (deformed) radially outward when the rotor shaft is pressed in, thereby reducing the surface pressure on the contact end when the rotor shaft is pressed in.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-58697 Utility Model Content

[0004] In a rotary electric machine including a rotor core with an elongated hole as described above, when the rotor shaft rotates, the elongated hole expands circumferentially due to the centrifugal force acting on the rotor core, and stress is generated around both ends of the elongated hole, causing the inner portion of the elongated hole to press against the rotor shaft. Furthermore, as with the rotor core described in Patent Document 1, if the curvature of the portions forming the two ends of the elongated hole is small, stress concentrates in these portions, potentially causing stress in the rotor core to exceed its allowable stress. In contrast, by forming the two ends of the elongated hole into concave cylindrical surfaces with a diameter close to the radial length of the rotor core containing the elongated hole, stress concentration can be suppressed by ensuring the curvature of the portions forming the two ends of the elongated hole. However, in this case, the strength of the rotor core may be insufficient due to the increased opening area at both ends of the elongated hole.

[0005] Therefore, the main objective of this invention is to reduce the surface pressure acting on the mating surface when pressing the shaft into the rotor core, and to ensure the strength of the rotor core.

[0006] The rotor of the rotary electric motor of this invention includes an annular rotor core and a shaft pressed into a shaft hole in the rotor core. The rotor core includes a plurality of elongated holes, which are spaced apart in the circumferential direction, extending along the shaft hole along the circumferential direction of the rotor core and extending axially along the central axis of the shaft hole. The inner circumferential surface of each elongated hole includes: a pair of first surfaces extending along the circumferential direction and radially opposite the rotor core; two second surfaces forming the ends of the elongated holes in the circumferential direction; and four third surfaces each having a radius of curvature larger than that of the surface contained in the second surfaces, and continuous with the corresponding first and second surfaces.

[0007] In the rotor core of the rotary electric motor of this invention, a plurality of elongated holes extend circumferentially along the shaft hole of the rotor core and axially along the central axis of the shaft hole, and are spaced apart circumferentially. This reduces the surface pressure acting on the mating surfaces when the shaft is pressed into the rotor core, thereby suppressing burrs on the outer circumferential surface of the shaft or scratches on the inner circumferential surface of the shaft hole (rotor core). Furthermore, the inner circumferential surface of the elongated holes includes a pair of first surfaces, two second surfaces, and four third surfaces. The pair of first surfaces extends circumferentially along the rotor core and is radially opposed to the rotor core. The two second surfaces form the ends of the elongated holes circumferentially in the rotor core. The four third surfaces each have a radius of curvature larger than the radius of curvature of the surface included in the second surfaces, and are continuous with the corresponding first and second surfaces. This ensures the radius of curvature of the surfaces included in the second surface and increases the radius of curvature of the third surface to suppress the increase in the opening area at the end of the elongated hole, thereby suppressing stress concentration around the end of the elongated hole and ensuring rigidity. As a result, the surface pressure acting on the mating surface when pressing the shaft into the rotor core can be reduced, and the strength of the rotor core can be well ensured. Attached Figure Description

[0008] Figure 1 This is a schematic structural diagram showing the rotor of the rotary electric motor of this utility model.

[0009] Figure 2 This is a top view showing the elongated hole in the rotor core of the rotary electric motor formed in this invention.

[0010] Figure 3 This is an enlarged view of the main part of the elongated hole in the rotor core of the rotary electric motor formed in this invention. Detailed Implementation

[0011] Next, with reference to the accompanying drawings, specific embodiments of the present invention will be described.

[0012] Figure 1 This is a schematic structural diagram of the rotor 1 of the rotary electric motor of this utility model. Figure 1 The rotor 1 shown, together with the stator (not shown), constitutes a rotating electric motor (e.g., a three-phase AC motor), which is a so-called embedded magnet type (IPM type) rotor. As shown, the rotor 1 includes an annular rotor core 2, a plurality of permanent magnets 3 embedded in the rotor core 2 in such a manner as to form a plurality of magnetic poles, and a rotor shaft 4 fixed to the rotor core 2.

[0013] The rotor core 2 is formed by stacking multiple core plates 20, which are formed into annular shapes from electromagnetic steel sheets, for example, by stamping, in an axial direction. It includes a shaft hole 21, multiple (in this embodiment, for example, 16) magnet holding holes 22, and multiple (in this embodiment, for example, 8) elongated holes 23. The shaft hole 21, each magnet holding hole 22, and each elongated hole 23 are all formed by connecting the respective holes (slits) of the multiple core plates 20 stacked in the axial direction. Alternatively, the rotor core 2 can be formed, for example, by pressurizing and sintering strongly magnetic powder.

[0014] The shaft hole 21 of the rotor core 2 is a through hole with the axis of the rotor core 2 as its center. Furthermore, a plurality of magnet holding holes 22 are arranged on the rotor core 2 at predetermined intervals (in this embodiment, for example, 45° intervals) in pairs, each penetrating the rotor core 2 axially. A permanent magnet 3 is disposed (fixed) within each magnet holding hole 22. Thus, in this embodiment, eight magnetic poles are formed in the rotor core 2. Moreover, the plurality of elongated holes 23 are generally arc-shaped openings (slits), each formed at intervals in the circumferential direction along the shaft hole 21 and extending axially along the central axis of the shaft hole 21.

[0015] The rotor shaft 4 is made of metal, and an expanded portion (not shown) extends radially outward from the outer circumference, pressing into the shaft hole 21 to abut against one end face of the rotor core 2, thereby fixing it to the rotor core 2. Furthermore, a heat medium passage (not shown) is formed on the rotor shaft 4, through which a liquid heat medium (in this embodiment, such as ATF or other working oil) is supplied by a pump (not shown). The liquid heat medium supplied to the heat medium passage of the rotor shaft 4 flows through the radial hole formed in the rotor shaft 4 into the heat medium passage (not shown) formed in the rotor core 2, and exchanges heat with the rotor core 2, etc.

[0016] Figure 2 This is a top view showing the elongated hole 23 formed on the rotor core 2 of rotor 1. Figure 3These figures show enlarged views of the main portion of the elongated hole 23. As shown in these figures, the inner circumferential surface 230 of the elongated hole 23 includes a pair of first surfaces 231a and 231b, two second surfaces 232a and 232b, and four third surfaces 233a, 233b, 233c, and 233d. The pair of first surfaces 231a and 231b extend circumferentially along the rotor core 2 and are radially opposed to the rotor core 2. In this embodiment, the first surface 231a is a concave cylindrical surface, and the first surface 231b is a convex cylindrical surface.

[0017] Two second surfaces 232a and 232b respectively form the circumferential ends of the elongated holes 23 in the rotor core 2, and are formed symmetrically about the center line of the elongated holes 23 in this circumferential direction. In this embodiment, as... Figure 3 As shown, the second surface 232a includes a first concave cylindrical surface 232i continuous with the first surface 231a, a second concave cylindrical surface 232j continuous with the first surface 231b, and an intermediate surface 232m continuous with both the first and second concave cylindrical surfaces 232i and 232j. The radius of curvature of the first concave cylindrical surface 232i and the second concave cylindrical surface 232j can be the same or different from each other. In this embodiment, the intermediate surface 232m is a flat surface. The intermediate surface 232m can be a concave cylindrical surface with a radius of curvature larger than that of the first and second concave cylindrical surfaces 232i and 232j. Furthermore, the intermediate surface 232m can be omitted, or the first and second concave cylindrical surfaces 232i and 232j can be directly continuous.

[0018] In this embodiment, the four third surfaces 233a, 233b, 233c, and 233d are all concave cylindrical surfaces. The center lines of the third surfaces 233a and 233c are formed symmetrically with respect to the center lines of the elongated hole 23 in the circumferential direction, and the center lines of the third surfaces 233b and 233d are formed symmetrically with respect to the center lines of the elongated hole 23 in the circumferential direction.

[0019] Furthermore, the third surface 233a has a radius of curvature larger than the larger of the radii of curvature of the first concave cylindrical surface 232i and the second concave cylindrical surface 232j of the second surface 232a, and is continuous with both the first surface 231a and the first concave cylindrical surface 232i of the second surface 232a. Similarly, the third surface 233b has a radius of curvature larger than the larger of the radii of curvature of the first concave cylindrical surface 232i and the second concave cylindrical surface 232j of the second surface 232a, and is continuous with both the first surface 231b and the second concave cylindrical surface 232j of the second surface 232a. Furthermore, the third surface 233c has a radius of curvature larger than the larger of the radii of curvature of the first concave cylindrical surface (not shown) and the second concave cylindrical surface of the second surface 232b, and is continuous with both the first surface 231a and the first concave cylindrical surface of the second surface 232b. Furthermore, the third surface 233d has a radius of curvature larger than that of the first concave cylindrical surface and the second concave cylindrical surface of the second surface 232b, and is continuous between the first surface 231b and the second concave cylindrical surface of the second surface 232b.

[0020] In the rotor 1 constructed as described above, a plurality of elongated holes 23 extend circumferentially along the shaft hole 21 of the rotor core 2 and axially along the central axis of the shaft hole 21 of the rotor core 2, thus being spaced apart circumferentially. This reduces the surface pressure acting on the mating surface when the rotor shaft 4 is pressed into the shaft hole 21 of the rotor core 2, thereby suppressing the formation of burrs on the outer circumferential surface of the rotor shaft 4 or dents on the inner circumferential surface of the shaft hole 21 (rotor core 2). Furthermore, the number of elongated holes 23 in the rotor core 2 is not limited to eight, and can be arbitrarily determined according to the required degree of surface pressure reduction.

[0021] Furthermore, the inner circumferential surface 230 of the elongated hole 23 includes a pair of first surfaces 231a and 231b, two second surfaces 232a and 232b, and four third surfaces 233a, 233b, 233c, and 233d. The pair of first surfaces 231a and 231b extend circumferentially along the rotor core 2 and are radially opposed to the rotor core 2. The two second surfaces 232a and 232b form the ends of the elongated hole 23 in the circumferential direction of the rotor core 2. The four third surfaces 233a, 233b, 233c, and 233d each have a radius of curvature larger than that of the first concave cylindrical surface (curved surface), the second concave cylindrical surface 232i, 232j, etc., included in the second surfaces 232a and 232b, and are continuous with the corresponding first surface 231a or 231b and second surface 232a or 232b.

[0022] Therefore, it is possible to prevent the radii of curvature of the first concave cylindrical surface 232i, the second concave cylindrical surface 232j, etc., included in the second surfaces 232a and 232b from becoming too small, and to increase the radii of curvature of the third surfaces 233a, 233b, 233c, and 233d to suppress the increase in the opening area at both ends of the elongated hole 23. That is, if the ends of the elongated hole 23 are divided by a concave cylindrical surface having a diameter close to the radial length of the rotor core 2 of the elongated hole 23 (see reference). Figure 3 Comparing the dashed lines in the diagram, then in rotor 1, as shown... Figure 3 As shown, the second surfaces 232a and 232b can be formed by extending along the concave cylindrical surfaces shown by the dashed lines in the figure, and the radii of curvature of the first concave cylindrical surface 232i and the second concave cylindrical surface 232j are sufficiently ensured. Furthermore, by making the radii of curvature of the third surfaces 233a, 233b, 233c, and 233d larger than the radii of curvature of the first concave cylindrical surface 232i and the second concave cylindrical surface 232j, the third surfaces 233a and 233b can be brought closer together, and the third surfaces 233c and 233d can be brought closer together, thereby ensuring that the area around the elongated hole 23... Figure 3 The flesh is increased within the shaded area of ​​the hole. Therefore, stress concentration can be suppressed around both ends of the elongated hole 23, and rigidity can be ensured. As a result, in the rotor 1, when the rotor shaft 4 is pressed into the rotor core 2, the surface pressure acting on the mating surface can be reduced, and the strength of the rotor core 2 can be well ensured.

[0023] Furthermore, this utility model is not limited to the above-described embodiments, and various modifications can be made within the scope of this utility model. Moreover, the above-described embodiments are merely one specific way of describing the utility model content as recorded in the summary section of the utility model, and are not limited to the elements of the utility model as recorded in the content section of the utility model.

[0024] Industrial availability

[0025] The utility model disclosed herein can be used in industries such as the manufacturing of rotating electric machines.

[0026] Symbol Explanation

[0027] 1-Rotor, 2-Rotor core, 3-Permanent magnet, 4-Rotor shaft, 20-Core plate, 21-Shaft hole, 22-Magnet holding hole, 23-Elongated hole, 230-Inner circumferential surface, 231a, 231b-First surface, 232a, 232b-Second surface, 232i-First concave cylindrical surface, 232j-Second concave cylindrical surface, 232m-Intermediate surface, 233a, 233b, 233c, 233d-Third surface.

Claims

1. A rotor of a rotary electric machine characterized by comprising: It includes a ring-shaped rotor core and a shaft press-fitted into a shaft hole of the rotor core, wherein The rotor core includes a plurality of long holes formed at intervals in a circumferential direction along the rotor core along the shaft hole, respectively, and extending in an axial direction of the rotor core along a central axis of the shaft hole, Inner circumferential surfaces of the long holes include a pair of first surfaces respectively extending along the circumferential direction and facing diametrically opposite to the rotor core, two second surfaces respectively forming end portions of the long holes in the circumferential direction, and four third surfaces respectively having a curvature radius larger than that of a curved surface included in the second surfaces and being continuous with the corresponding first surfaces and the second surfaces.

Images