Motor shaft structure

Abstract

To make the diameter of a motor shaft smaller when the shaft is scraped off and reduce the amount of trash to be produced.SOLUTION: The motor shaft structure of the present invention includes: a ring-like laminated rotor core (6) provided in a rotor core receiver (2) of a motor shaft (1); a magnet (5) in the ring-like laminated rotor core (6); and an end plate (7) coaxially inserted in the motor shaft (1), the end plate having an abutting unit (7C) abutting against a step unit (21) of the rotor core receiving unit (2). One end surface (7B) of the end plate (7) has a function of preventing removal of the magnet (5)) from the ring-shaped laminate rotor core (6).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor shaft structure, and in particular to a new improvement that uses an independent end plate instead of the conventional flange portion integral with the motor shaft, thereby enabling the abutment of the annular laminated rotor core, the prevention of magnets from falling out, and the axial positioning of the first bearing. [Background technology]

[0002] Conventionally, this type of motor shaft structure has been configured such that multiple holes are provided around the periphery of the rotor core, and a pair of end plates are provided through these holes to fasten the rotor core, as shown in FIG. 6 of Patent Document 1. Further, although no patent document or the like is disclosed, the configuration shown in FIG. 4 manufactured and sold by the present applicant can be mentioned. That is, in Figure 4, what is indicated by the symbol 1 is a motor shaft having first and second shaft portions 3 and 4 extending in different directions on both sides of a rotor core receiving portion 2, and an annular laminated rotor core 6 having a magnet 5 is fitted to the outer periphery 2A of the rotor core receiving portion 2.

[0003] A disk-shaped flange portion 7 is provided adjacent to the annular laminated rotor core 6 on the motor shaft 1, and this flange portion 7 is formed by cutting out the solid shaft material RA integrally when cutting the motor shaft 1.

[0004] First and second bearing portions 8, 9 are formed integrally with the motor shaft 1 at both sides of the rotor core receiving portion 2, and first and second bearings 10, 11 are provided in the bearing portions 8, 9, respectively. Figure 5 is an enlarged cross-sectional view of the main part of Figure 4, in which a second relief R portion 2B is formed at the end of the rotor core receiving portion 2, and a first relief R portion 8B is also formed at the end of the first bearing portion 8.

[0005] FIG. 6 shows the state in which the conventional motor shaft 1 of FIG. 4 is machined from a solid shaft material RA. The outer diameter of this cylindrical shaft material RA matches the outer diameter of the flange portion 7. The hatched area in FIG. 6 is the machining allowance R1, and the motor shaft 1 is completed by machining down to the outer diameters of the first and second shaft portions 3, 4, the first and second bearing portions 8, 9, and the rotor core receiving portion 2. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-146186 Summary of the Invention [Problem to be solved by the invention]

[0007] The conventional motor shaft structure, configured as described above, has the following problems. That is, in the case of the configuration shown in FIG. 6 of the above-mentioned Patent Document 1, a pair of end plates and a plurality of connecting rods are required, resulting in a complicated structure. Furthermore, in the case of the conventional configuration shown in Figures 4 to 6, the rotor core receiving portion 2 and the flange portion, i.e., the end plate 7, are cut out as a single unit. Because the outer diameter of the solid shaft material RA matches the outer diameter of the flange portion 7, the cutting allowance R1 is large for each of the shaft portions 3 and 4, the rotor core receiving portion 2, and each of the bearing portions 8 and 9 other than the flange portion 7, and the amount of waste material from cutting increases with mass production, resulting in a huge loss. Furthermore, it is necessary to form the first relief R portion 8B due to the installation of the first bearing 10 and the second relief R portion 2B due to the installation of the annular laminated rotor core 6, which is a factor in increasing costs. [Means for solving the problem]

[0008] The motor structure according to the present invention comprises an annular laminated rotor core provided on a rotor core receiving portion of a motor shaft, a magnet provided within the annular laminated rotor core, and an end plate inserted coaxially on the motor shaft and having an abutment portion that abuts against a stepped portion of the rotor core receiving portion, one end face of the end plate abutting against the entire end face of the magnet to prevent the magnet from coming off the annular laminated rotor core, a first bearing and a second bearing disposed on both sides of the rotor core receiving portion of the motor shaft, and a cylindrical portion provided on the other end face of the end plate, Tip surface of is configured to contact only the inner ring of the first bearing and to have the function of axially positioning the first bearing, and by having chamfered corners at the corners of the abutting portion of the end plate against the stepped portion, it is not necessary to form a relief R portion in the first bearing portion and rotor core receiving portion of the motor shaft, and the motor shaft is formed by cutting out a solid shaft material, and the end plate is formed as a single component from a separate member that is unrelated to the cutting out of the shaft material, and the outer diameter of the shaft material is the same as the outer diameter of the rotor core receiving portion. [Effects of the Invention]

[0009] The motor shaft structure according to the present invention is configured as described above, and therefore has the following advantages. That is, it comprises an annular laminated rotor core provided in the rotor core receiving portion of the motor shaft, a magnet provided within the annular laminated rotor core, and an end plate inserted coaxially on the motor shaft and having an abutment portion that abuts against a stepped portion of the rotor core receiving portion, and one end face of the end plate is configured to have the function of preventing the magnet from coming out of the annular laminated rotor core. This eliminates the need to provide a separate flange on the motor shaft to position the laminated rotor core or a step to position the bearing, making it easier to process and manage the dimensions of the motor shaft. Furthermore, axial positioning control in the assembly equipment becomes unnecessary, and assembly yields are improved. The motor shaft further comprises a first bearing and a second bearing arranged on both sides of the rotor core receiving portion, and a cylindrical portion provided on the other end surface of the end plate. The cylindrical portion is configured to contact only the inner ring of the first bearing and to have the function of positioning the first bearing in the axial direction, thereby eliminating bearing play and enabling the motor shaft to be positioned at the axial center position without any post-operation. Furthermore, by providing a chamfered corner at the abutting portion of the end plate against the stepped portion, it is possible to achieve a configuration in which it is not necessary to form a relief R portion in the first bearing portion and rotor core receiving portion of the motor shaft. Furthermore, since the motor shaft is formed by cutting out a solid shaft material and the end plate is formed as a single component from a separate material unrelated to the cutting out of the shaft material, the outer diameter of the shaft material can be made significantly smaller than conventional outer diameters, and the amount of shavings can also be significantly reduced. Furthermore, because the outer diameter of the shaft material is the same as the outer diameter of the rotor core receiving portion, the outer peripheral surfaces of the shaft material and the rotor core receiving portion are flush, which allows the outer diameter of the shaft material to be reduced as in the previous section, significantly contributing to cost reduction. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing the overall configuration of a motor shaft structure according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main part of FIG. [Figure 3] FIG. 2 is a cross-sectional view of the motor shaft material of FIG. 1 before cutting. [Figure 4] FIG. 1 is a cross-sectional view showing the overall configuration of a conventional motor shaft structure. [Figure 5] FIG. 5 is an enlarged cross-sectional view of a main part of FIG. 4. [Figure 6] FIG. 10 is a cross-sectional view of a shaft material of a conventional motor shaft structure before cutting. DETAILED DESCRIPTION OF THE INVENTION

[0011] The motor shaft structure of the present invention uses an independent end plate instead of the conventional flange that is integral with the motor shaft. This allows the outer diameter of the shaft material to be smaller than conventional shafts, making it possible to butt the annular laminated rotor core, prevent the magnet from falling out, and even position the first bearing in the axial direction. [Example]

[0012] Hereinafter, preferred embodiments of the motor shaft structure according to the present invention will be described with reference to the drawings. In addition, parts that are the same as or equivalent to those in the conventional example are denoted by the same reference numerals. In Figure 1, the reference numeral 1 denotes a motor shaft having first and second shaft portions 3 and 4 extending in different directions on either side of a rotor core receiving portion 2, and an annular laminated rotor core 6 having a magnet 5 is fitted to the outer periphery 2A of the rotor core receiving portion 2.

[0013] A disk-shaped end plate 7 is provided adjacent to the annular laminated rotor core 6 on the motor shaft 1, and this end plate 7 is formed as a single component from an entirely separate material, rather than being cut out from a solid shaft material RA by cutting as in the conventional method.

[0014] First and second bearing portions 8, 9 are formed integrally with the motor shaft 1 on both sides of the rotor core receiving portion 2 of the motor shaft 1, and first and second bearings 10, 11 are provided in the bearing portions 8, 9, respectively.

[0015] FIG. 2 is an enlarged cross-sectional view showing the main part of FIG. 1, in which an annular laminated rotor core 6 having magnets 5 is fitted or otherwise attached to the outer periphery 2A of the rotor core receiving portion 2, and the end plate 7 is fitted or otherwise attached to the outer periphery 8A of the first bearing portion 8. The abutment portion 7C consisting of one end face 7B of the end plate 7 abuts against the end faces of the magnet 5 and the annular laminated rotor core 6, preventing the magnet 5 from popping out or slipping out of the annular laminated rotor core 6, providing a so-called anti-pullout function, and preventing the annular laminated rotor core 6 from popping out in the same manner as described above.

[0016] The cylindrical portion 20 formed integrally at the center of the end plate 7 is fitted onto the outer periphery 8A of the first bearing portion 8, as shown in Figures 1 and 2, and a corner chamfer 10B is formed at the corner 10A of this cylindrical portion 7. The tip end surface 20A of the cylindrical portion 20 abuts only against the inner ring 10a of the first bearing 10, thereby achieving positioning of the first bearing 10.

[0017] The end plate 7 is arranged coaxially with the motor shaft 1, and is available in a variety of shapes depending on the size, such as cylindrical or flanged. The end plate 7 is inserted into the stepped portion 21 of the motor shaft 1 by abutting against it, but it does not matter whether it is bonded, press-fitted, simply inserted, or fixed. One end of the end plate 7 functions as a butt for the annular laminated rotor core 6 and as a cover for preventing the magnet 5 from falling off, that is, for prevention, but it does not matter whether both or only one of them is used. By making the corner chamfer 10B of the abutting portion 7C of the end plate 7 large, machining of the first and second relief R portions 8B, 2B etc. shown in the conventional example of FIG. 4 becomes unnecessary, thereby shortening the machining time and reducing costs. The material of the end plate 7 may be either non-magnetic or magnetic.

[0018] FIG. 3 shows the state in which the motor shaft 1 according to the present invention is manufactured by cutting out a cutting allowance R1 from a solid shaft material RA. As is clear from a comparison of the outer diameter of the shaft material RA in Figures 3 and 6, as mentioned above, the outer diameter of the shaft material RA is determined by whether the end plate 7 is integrated with the motor shaft 1 or is a separate body, and the outer diameter of the shaft material RA of the motor shaft 1 in this embodiment is smaller than that of the conventional one. In Figure 3, R1 indicates the cutting allowance, and R2 and R3 indicate the outer diameters of the shaft portions 3 and 4 of the shaft material RA, which clearly shows how the configuration of the motor shaft 1 of this embodiment requires a smaller outer diameter. [Industrial Applicability]

[0019] In the motor shaft structure of the present invention, the end plates for holding the axial laminated rotor core on the motor shaft are not machined integrally with the motor shaft, but are machined separately and attached after the motor shaft is machined. This reduces the amount of material that needs to be machined from the motor shaft material, eliminates the need to form a relief R portion on the motor shaft, and allows for an inexpensive motor shaft to be obtained. [Explanation of symbols]

[0020] 1 Motor shaft 2 Rotor core support 2A outer circumference 3 First shaft 4 Second shaft 5. Magnet 6 Annular laminated rotor core 7 End plate 7A Other end surface 7B One end face 7C Stop part 8 1st bearing part 8A Outer circumference 9 Second bearing part 10 First bearing 10A Corner 10a Inner Ring 10B Corner chamfer 11 Second bearing 20 Cylinder part 20A tip surface 21 Step R1 Cutting allowance RA shaft material

Claims

1. a ring-shaped laminated rotor core (6) provided on a rotor core receiving portion (2) of a motor shaft (1); a magnet (5) provided in the ring-shaped laminated rotor core (6); and an end plate (7) inserted coaxially on the motor shaft (1) and having an abutment portion (7C) abutting against a stepped portion (21) of the rotor core receiving portion (2); a first bearing (10) and a second bearing (11) disposed on both sides of the rotor core receiving portion (2) of the motor shaft (1), and a cylindrical portion (20) provided on the other end surface (7A) of the end plate (7), One end surface (7B) of the end plate (7) is configured to abut against the entire end surface of the magnet (5) and has a function of preventing the magnet (5) from slipping out of the annular laminated rotor core (6), a tip end surface (20A) of the cylindrical portion (20) that abuts only against an inner ring (10a) of the first bearing (10) and that has a function of axially positioning the first bearing (10).

2. 2. The motor shaft structure according to claim 1, wherein a corner (10A) of the abutting portion (7C) against the stepped portion (21) of the end plate (7) has a chamfered portion (10B), thereby eliminating the need to form a relief R portion in the first bearing portion (8) and the rotor core receiving portion (2) of the motor shaft (1).

3. 3. The motor shaft structure according to claim 1, wherein the motor shaft (1) is formed by cutting out a solid shaft material (RA), and the end plate (7) is formed as a single component from a separate member unrelated to the cutting out of the shaft material (RA).

4. 4. The motor shaft structure according to claim 3, wherein the outer diameter of the shaft material (RA) is the same as the outer diameter of the rotor core receiving portion (2).

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