JP6844282B2 - Electric motor - Google Patents

Description

The present invention relates to an electric motor including a rotor having a rotor core on which electrical steel sheets are laminated.

As a conventional electric motor, an inner rotor type electric motor in which a rotor having a permanent magnet is rotatably arranged inside a stator that generates a rotating magnetic field is known. This type of electric motor includes, for example, a brushless DC motor for rotationally driving a blower fan mounted on an outdoor unit of an air conditioner.

The rotor of such an electric motor penetrates in the direction of an annular permanent magnet in which a plurality of permanent magnet pieces are arranged at equal intervals, a cylindrical rotor core located on the inner diameter side of the permanent magnet, and a central axis of the rotor core. It has a shaft fixed to the through hole. In the rotor core of this rotor, for example, a plurality of laminated electromagnetic steel sheets are fixed to the shaft. Then, the rotor core and the shaft are crimped around the through hole of the rotor core into which the shaft is inserted by using a caulking jig to prevent the rotor core from coming off in the axial direction and idling in the circumferential direction.

However, such a rotor structure is particularly used in an environment where shock or vibration is applied to the electric motor itself, that is, in a situation where the blower fan mounted on the outdoor unit of the air conditioner is rotationally driven. Due to insufficient strength in the axial direction, the rotor core fixed to the shaft may be displaced or fall off from the shaft. This is because when a rotor core in which a plurality of electromagnetic steel plates are laminated is crimped, the tip of the caulking jig has a constant inclination angle with respect to the outer peripheral surface of the shaft, so that the positions of the surface layer and the deep layer in the stacking direction of the rotor core One of the causes is that the caulking allowance becomes uneven.

As a rotor for compensating for such insufficient strength, for example, a rotor core made of a plurality of laminated electromagnetic steel sheets and a shaft having a plurality of axially extending retaining grooves on the outer peripheral surface are proposed. Has been done. A plurality of rotor cores are deformed by inserting the shaft into the through hole of the rotor core and caulking the circumference of the through hole of the rotor core into which the shaft is inserted by using a caulking jig. It has a structure that allows it to enter the retaining groove (see, for example, Patent Document 1).

Utility Model Registration No. 2596085

However, in the rotor disclosed in Patent Document 1, it is difficult to process because a plurality of retaining grooves extending in the axial direction are formed on the outer peripheral surface of the shaft.

In view of the above problems, it is an object of the present invention to provide an electric motor capable of ensuring sufficient joint strength when the rotor core is crimped to the shaft by using a shaft that is easy to process.

In order to solve the above problems, the electric motor of the present invention includes a stator and a rotor arranged inside the stator, and the rotor includes an annular permanent magnet and a cylindrical rotor core and a shaft.
The rotor core is provided with a through hole through which an electromagnetic steel plate is laminated on the inner diameter side of the permanent magnet and penetrates in the direction of the central axis, and the shaft is inserted through the through hole.
Further, the shaft is provided at a position facing both end faces in the axial direction of the rotor core and has an annular retaining groove in the circumferential direction of the outer peripheral surface of the shaft, and the electromagnetic steel plate is inserted into the retaining groove. ..

According to the electric motor of the present invention, the shaft can be made into a structure that is easy to process. Further, sufficient joint strength can be ensured when the rotor core is crimped to the shaft.

It is explanatory drawing which shows the whole structure of the electric motor by this invention. It is explanatory drawing which shows the rotor of the electric motor by this invention, (a) is a plan view, (b) is a side view including a partial cross section. It is explanatory drawing which shows the rotor of the electric motor by this invention, (a) corresponds to the A arrow view part of FIG.2 (b), and is the cross-sectional view which shows the state before the rotor core is caulked by the shaft, (b). 2 corresponds to the A arrow-viewing portion of FIG. 2B, and is a cross-sectional view showing a state in which the rotor core is crimped to the shaft, and FIG. 2C shows another embodiment of the A arrow-viewing portion of FIG. 2B. Correspondingly, the cross-sectional view showing the state before the rotor core is crimped to the shaft, (d) corresponds to another embodiment of the A arrow-viewing portion of FIG. 2 (b), and the state where the rotor core is crimped to the shaft is shown. It is sectional drawing which shows.

<Overall configuration of the motor>
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 are views for explaining the configuration of the electric motor according to the present embodiment. As shown in FIGS. 1 to 3, the electric motor 1 is, for example, a brushless DC motor, and is used to rotationally drive a blower fan mounted on an outdoor unit of an air conditioner. In the following, an inner rotor type electric motor 1 in which a rotor 3 having a permanent magnet 31 is rotatably arranged inside a stator 2 that generates a rotating magnetic field will be described as an example. As shown in FIG. 1, the electric motor 1 in the present embodiment includes a stator 2, a rotor 3, a circuit board 4, a first bearing 51, a second bearing 52, and a motor outer shell 6.

<Stator, rotor and circuit board>
The stator 2 includes a stator core 21 having a cylindrical yoke portion and a plurality of teeth portions extending from the yoke portion to the inner diameter side, and a winding 23 is wound around the teeth portion via an insulator 22. The rotor 3 has an annular permanent magnet 31 and a shaft 33, and the permanent magnet 31 is integrally arranged around the shaft 33 via a rotor core 32 described later. The rotor 3 is rotatably arranged on the inner peripheral side (inner peripheral surface of the teeth portion) of the stator core 21 of the stator 2 with a predetermined gap. The circuit board 4 is equipped with a control unit for generating a rotating magnetic field, and is fixed to one end surface side (left side in FIG. 1) of the stator 2.

<1st bearing, 2nd bearing and motor outer shell>
The first bearing 51 supports one end side (output side) of the shaft 33 of the rotor 3. The second bearing 52 supports the other end side (counter-output side) of the shaft 33 of the rotor 3. For the first bearing 51 and the second bearing 52, for example, ball bearings are used.

The motor outer shell 6 includes a first bracket 61 and a second bracket 62. The first bracket 61 is made of metal (steel plate, aluminum, etc.) and covers the other end face side (right side in FIG. 1) of the stator 2 and the output side of the shaft 33 of the rotor 3. The first bracket 61 has a cylindrical first bracket main body portion 611 having a bottom surface and a first bearing accommodating portion 612 provided on the bottom surface for accommodating the first bearing 51. The first bearing accommodating portion 612 is formed in a cylindrical shape having a bottom surface, has a hole in the center of the bottom surface, and the output side of the shaft 33 projects from this hole.

The second bracket 62 is made of metal (steel plate, aluminum, etc.) and covers one end surface side (left side in FIG. 1) of the stator 2, the counter-output side of the shaft 33 of the rotor 3, and the circuit board 4. .. The second bracket 62 has a cylindrical second bracket main body portion 621 having a bottom surface and a second bearing accommodating portion 622 provided on the bottom surface for accommodating the second bearing 52. The second bearing accommodating portion 622 is formed in a cylindrical shape having a bottom surface.

In the first bracket 61, the first bearing 51 is housed in the first bearing accommodating portion 612, and one end surface side (right side in FIG. 1) of the stator core 21 of the stator 2 is accommodated in the first bracket main body portion 611. There is. In the second bracket 62, the second bearing 52 is housed in the second bearing accommodating portion 622, and the other end surface side (left side in FIG. 1) of the stator core 21 of the stator 2 is accommodated in the second bracket main body portion 621. There is. By fixing the first bracket 61 and the second bracket 62 to each other, the motor 1 in which the stator 2 and the rotor 3 are integrated with respect to the motor outer shell 6.

<Detailed configuration of rotor>
As shown in FIG. 2, the electric motor 1 configured as described above includes a rotor 3 fixed by caulking the rotor core 32 onto the shaft 33. Hereinafter, the rotor 3 will be described. As shown in FIG. 2, the rotor 3 includes a permanent magnet 31, a rotor core 32, and a shaft 33 from the outer diameter side to the inner diameter side.

The permanent magnet 31 is formed in an annular shape, and a plurality of (for example, eight) permanent magnet pieces 311 are arranged so that the north and south poles appear alternately at equal intervals in the circumferential direction. As the permanent magnet 31, a plastic magnet formed in an annular shape by solidifying the magnet powder with a resin may be used. The rotor core 32 is formed in a cylindrical shape by a laminated structure in which a plurality of electromagnetic steel sheets are laminated, and is arranged on the inner diameter side of the permanent magnet 31. The rotor core 32 is provided with a through hole 321 penetrating in the direction of the central axis O at the center. The shaft 33 is inserted into a through hole 321 provided in the rotor core 32, and the rotor core 32 is an annular shape having both end surfaces in the axial direction (one end surface in the axial direction 322 and the other end surface in the axial direction 323) in the vicinity of the through hole 321. It is pressed against the shaft 33 by being crimped in an annular shape by the tip of the shaft. As a result, the shaft 33 of the rotor core 32 is prevented from coming off in the axial direction and idling in the circumferential direction.

<Structure, action and effect of rotor characteristic of the present invention>
Next, in the electric motor 1 of the present embodiment, the structure of the rotor 3, which is a feature of the present invention, and its action and effect will be described with reference to FIGS. 2 and 3. In the configuration of the rotor 3 described above, as described in the column of background technology, the blower fan mounted on the outdoor unit of the air conditioner, which is in an environment where the electric motor 1 itself is subject to shock or vibration, is rotationally driven. When used in various situations, it has the following problems.

In the electric motor 1 mounted on the outdoor unit of an air conditioner used in an outdoor environment, the rotor core 32 fixed to the shaft 33 may be displaced or fall off from the shaft 33 due to insufficient strength in the axial direction. It was. This is because when the rotor core 32 in which a plurality of electromagnetic steel plates are laminated is crimped from the axial direction by the tip of the caulking jig, the tip of the caulking jig has a constant inclination angle with respect to the outer peripheral surface 331 of the shaft 33. Therefore, one of the causes of insufficient strength is that the caulking allowance becomes non-uniform depending on the positions of the surface layer and the deep layer in the stacking direction of the rotor core 32.

In the configuration of the rotor 3 described above, in order to compensate for such a lack of strength, a plurality of retaining grooves extending in the axial direction on the outer peripheral surface like the rotor described in Patent Document 1 described in the column of background technology. A part of the through hole of the rotor core is deformed by inserting the shaft into the through hole of the rotor core and caulking the circumference of the through hole of the rotor core into which the shaft is inserted by using a caulking jig. It is sufficient to make the structure so that it can be inserted into a plurality of retaining grooves, but there are the following problems. Since a plurality of retaining grooves extending in the axial direction are formed on the outer peripheral surface of the shaft, it is difficult to process.

Therefore, in the rotor 3 according to the present embodiment, as shown in FIG. 2B, the shaft 33 is located at a position facing the axial end surface 322 of the rotor core 32 and is annular in the circumferential direction of the outer peripheral surface 331 of the shaft 33. A retaining groove 332 is provided, and an annular retaining groove 333 is provided in the circumferential direction of the outer peripheral surface 331 of the shaft 33 at a position facing the other end surface 323 in the axial direction of the rotor core 32. Since the retaining groove 332 and the retaining groove 333 have the same structure, only the retaining groove 332 will be described below, and the description of the retaining groove 333 will be omitted.

As shown in FIG. 3A, the retaining groove 332 has a concave cross section, and its bottom surface 332a is formed so as to have a constant depth from the outer peripheral surface 331. The depth of the retaining groove 332 corresponds to the length at which the inner peripheral side of the through hole 321 of the rotor core 32 is deformed by caulking the rotor core 32 with the caulking jig K and the rotor core 32 enters the retaining groove 332. It is deep enough to do. The axial width of the retaining groove 332 is a width corresponding to the caulking depth of the tip portion K1 of the caulking jig K. The caulking depth is a depth corresponding to the thickness in the stacking direction of the electromagnetic steel sheet in which deformation occurs on the inner peripheral side of the through hole 321 of the rotor core 32.

Next, the process of caulking the rotor core 32 onto the shaft 33 will be described with reference to FIGS. 3 (a) and 3 (b). Since the rotor core 32 is crimped simultaneously with respect to the retaining groove 332 and the retaining groove 333 from the axial direction, the retaining groove 333 is not shown. Further, it is assumed that the shaft 33 is inserted into the through hole 321 of the rotor core 32 and the relative positions of the shaft 33 and the rotor core 32 are fixed before the rotor core 32 is crimped.

First, in the state of FIG. 3A, a crimping jig is used in the vicinity of the through hole 321 of the rotor core 32 with respect to the axial end surface 322 and the axial other end surface 323, which are the axial end surfaces of the rotor core 32. A caulking load is applied by the annular tip portion K1 of K. As a result, as shown in FIG. 3B, the inner peripheral side of a part of the through hole 321 of the rotor core 32 is deformed toward the bottom surface 332a of the retaining groove 332 and the bottom surface 333a of the retaining groove 333. The rotor core 32 is in a state of being inserted into the retaining groove 332 and the retaining groove 333. As shown in FIG. 3B, the amount of deformation of the through hole 321 on the inner peripheral side at this time decreases as the caulked portion becomes deeper in the stacking direction of the electromagnetic steel sheet, so that the rotor core 32 has a larger amount of deformation. It is pressed against the shaft 33 at a portion shallow in the laminating direction of the electromagnetic steel sheet.

According to the electric motor 1 according to the present embodiment described above, the shaft 33 is formed with one retaining groove 332 and one retaining groove 333, so that the shaft 33 can be easily machined. Further, when the rotor core 32 on which the electromagnetic steel sheets are laminated is crimped to the shaft 33, a part of the laminated portion of the rotor core 32 enters the retaining groove 332 and the retaining groove 333, respectively, and is pressure-welded to the bottom surface 332a and the bottom surface 333a, respectively. Therefore, it is possible to secure sufficient joint strength of the rotor core 32 with respect to the shaft 33. Then, as shown in FIG. 3B, the rotor core 32 is crimped to the bottom surface 332a of the retaining groove 332 and the bottom surface 333a of the retaining groove 333, and the deformed portion on the inner peripheral side of the through hole 321 is pressure-welded. As a result, a step S1 is formed, and the rotor core 32 is in a state of biting into the step S1, so that it is possible to strengthen the prevention of the rotor core 32 from coming off in the axial direction. Further, since the retaining groove 332 and the retaining groove 333 each have a step S2, as shown by the dotted line, the axial end surface 322 and the axial other end surface 323 of the rotor core 32 are aligned with the positions of the step S2. By setting the dimensions of the rotor core 32, the retaining groove 332, and the retaining groove 333, the step S2 serves as an axial stopper of the rotor core 32 to prevent the rotor core 32 from coming off in the axial direction. be able to.

<Groove for retaining in other examples>
Next, another embodiment of the retaining groove 332 and the retaining groove 333 provided on the shaft 33 will be described with reference to FIGS. 3 (c) and 3 (d). Since the retaining groove 332 and the retaining groove 333 have the same structure, only the retaining groove 332 will be described below, and the description of the retaining groove 333 will be omitted. Further, the bottom surface 332b of the retaining groove 332, which is a portion different from the above-described embodiment, will be mainly described.

As shown in FIG. 3C, the retaining groove 332 has a concave cross section, and its bottom surface 332b is formed so as to be inclined in the same inclination direction as the inclination of the tip portion K1 of the caulking jig K. There is. Since the bottom surface of the retaining groove 333 (not shown) is crimped from the axial direction by the tip K1 of the caulking jig K with respect to the axially opposite end surface 323 of the rotor core 32, the bottom surface of the retaining groove 332 is formed. The inclination of 332b is inclined so as to be symmetrical in the radial direction of the rotor core 32.

In the step of caulking the rotor core 32 to the shaft 33, first, in the state of FIG. 3C, in the state of FIG. 3C, the axial direction which is the axial end surface of the rotor core 32 in the vicinity of the through hole 321 of the rotor core 32, as in the above embodiment. A caulking load is applied to one end surface 322 and the other end surface 323 in the axial direction by the annular tip portion K1 of the caulking jig K from the axial direction. As a result, as shown in FIG. 3D, the inner peripheral side of a part of the through hole 321 of the rotor core 32 is deformed, and the bottom surface 332b of the retaining groove 332 and the bottom surface of the retaining groove 333 (not shown) are formed. The rotor core 32 is in a state of being inserted into the retaining groove 332 and the retaining groove 333. As shown in FIG. 3D, the deformation of the through hole 321 at this time on the inner peripheral side decreases as the caulked portion becomes deeper in the stacking direction of the electromagnetic steel sheets, as in the above-described embodiment. Since the bottom surface 332b of the retaining groove 332 and the bottom surface of the retaining groove 333 (not shown) are inclined in the same inclination direction as the inclination of the tip K1 of the caulking jig K, the retaining groove 332 The area pressed against the bottom surface 332b of the above and the bottom surface (not shown) of the retaining groove 333 is increased.

According to the electric motor 1 according to the other embodiment described above, similarly to the above-described embodiment, the shaft 33 is formed with one retaining groove 332 and one retaining groove 333, so that the shaft 33 can be processed. Can be facilitated. Further, the shaft 33 is formed so that the bottom surface 332b of the retaining groove 332 and the bottom surface of the retaining groove 333 (not shown) are inclined in the same inclination direction as the inclination of the tip end portion K1 of the caulking jig K, respectively. Therefore, when the rotor core 32 on which the electromagnetic steel plate is laminated is crimped to the shaft 33, a part of the laminated portion of the rotor core 32 enters the retaining groove 332 and the retaining groove 333, respectively, and the retaining groove 332 Since the area pressed against the bottom surface 332b and the bottom surface (not shown) of the retaining groove 333 is increased, the joint strength of the rotor core 32 with respect to the shaft 33 can be further strengthened. Then, as shown in FIG. 3D, the rotor core 32 is caulked and penetrates the bottom surface 332b of the retaining groove 332 and the bottom surface (not shown) of the retaining groove 333 as in the above-described embodiment. A step S3 is formed by pressure contacting the deformed portion on the inner peripheral side of the hole 321, and the rotor core 32 also bites into the step S3. Therefore, it is necessary to strengthen the prevention of the rotor core 32 from coming off in the axial direction. Can be done. Further, as in the above embodiment, since the retaining groove 332 and the retaining groove 333 each have a step S4, as shown by the dotted line, the axial end surface 322 and the axial other end surface 323 of the rotor core 32 are formed. By setting the dimensions of the rotor core 32, the retaining groove 332, and the retaining groove 333 so that the step S4 matches the position of the step S4, the step S4 becomes an axial stopper of the rotor core 32, and the shaft 33 of the rotor core 32 becomes. Can be prevented from coming off in the axial direction.

1 Motor 2 Steader 21 Stator core 22 Insulator 23 Winding 3 Rotor 31 Permanent magnet 311 Permanent magnet piece 32 Rotor core 321 Through hole 322 Axial one end surface 323 Axial other end surface 33 Shaft 331 Outer peripheral surface 332, 333 Retaining groove 332a 333a, 332b Bottom surface 4 Circuit board 51 1st bearing 52 2nd bearing 6 Motor outer shell 61 1st bracket 611 1st bracket main body 612 1st bearing housing 62 2nd bracket 621 2nd bracket main body 622 2nd bearing housing Part O Central axis K Caulking jig K1 Tip part S1, S2, S3, S4 Step

Claims (1)

It has a stator and a rotor placed inside the stator.
The rotor comprises an annular permanent magnet and a cylindrical rotor core and shaft.
The rotor core is provided with a through hole through which an electromagnetic steel plate is laminated on the inner diameter side of the permanent magnet and penetrates in the direction of the central axis, and the shaft is an electric motor inserted through the through hole.
The shaft is provided with an annular retaining groove in the circumferential direction of the outer peripheral surface of the shaft at a position facing both end faces in the axial direction of the rotor core.
The electromagnetic steel plate has entered the retaining groove ,
The retaining groove is inclined in the same inclination direction as the inclination direction of the tip of the caulking jig for crimping both end faces in the axial direction of the bottom surface of the retaining groove, which is closer to the retaining groove. An electric motor characterized by being formed so as to.

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