JP2002010544A - Permanent-magnet-type brushless dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a large-scale device unnecessary, to ensure simple processing and to prevent the break of a permanent magnet because of buckling and the like in a permanent-magnet-type brushless DC motor provided with a rotor with permanent magnets fixed inside long holes formed at equal intervals in its circumferential direction and a stator with magnetic poles wound with stator coils. SOLUTION: The long holes of the rotor are formed whose width is wider than the permanent magnets in the circumferential direction and spaces are provided at both sides in the circumferential direction of the permanent magnets set into those long holes. Both ends of non-magnetic metallic pipes inserted into the spaces are made to protrude out of the magnets and the end of the protrusions are plastically deformed to fix the magnets into the holes. The stainless steel is the most appropriate material as the metallic pipes. Available methods of plastically deforming both ends of these pipes are caulking and crushing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type brushless DC motor having a rotor in which permanent magnets are embedded at equal intervals in a circumferential direction.

[0002]

2. Description of the Related Art A permanent magnet brushless DC motor is known in which permanent magnets are embedded in a rotor at equal intervals in a circumferential direction, and the permanent magnets are opposed to magnetic poles of a stator to rotate the rotor. In this type of motor, there are an inner rotor type in which the permanent magnet of the rotor rotates facing the inner peripheral surface of the stator, and an outer rotor type in which the permanent magnet of the rotor rotates facing the outer peripheral surface of the stator. .

[0003] In a rotor used for such a motor, a magnet bush in which a thin plate of an electromagnetic steel sheet (such as a silicon steel sheet) is laminated on a drum made of a magnetic material such as iron is press-fitted and fixed, and provided on the magnet bush. A permanent magnet is loaded and fixed in the long hole. Here, the elongated hole is wide in the circumferential direction of the rotor, and penetrates the magnet bush in parallel with the rotation axis of the rotor.

A structure in which a plurality of permanent magnets are fixed at equal intervals in the circumferential direction of the rotor is usually called a magnet driving type (Interior Parmanent Magnet type, also referred to as IPM type) in this case. Air gaps are formed on both sides in the circumferential direction of the permanent magnet in order to prevent an inappropriate increase of the magnetic flux formed by the magnet (that is, leakage magnetic flux) and to effectively utilize the magnetic flux. That is, the circumferential width of the elongated hole is set to be larger than the circumferential width of the permanent magnet, and the gaps provided on both sides of the permanent magnet prevent the magnetic flux of the permanent magnet from expanding in the circumferential direction. When a permanent magnet narrower in the circumferential direction than the elongated hole is fixed in the elongated hole as described above, conventionally, an adhesive is used, or the permanent magnet is press-fitted into the elongated hole.

[0005]

When a permanent magnet is fixed with an adhesive, a thermosetting adhesive is usually used. Therefore, it is necessary to heat the permanent magnet after loading the permanent magnet in the long hole, and to dry at a high temperature. Requires a furnace. Also, the excess adhesive that overflows from the slots must be removed after curing. For this reason, the apparatus becomes large-scale and the processing is troublesome.

When a permanent magnet is press-fitted into a long hole,
A large load is applied to the permanent magnet. Some types of magnets are easily broken, and when a large load is applied to them, they are easily broken by buckling.

The present invention has been made in view of such circumstances, and when a permanent magnet is fixed to a rotor, a large-scale device is unnecessary, the processing is simple, and the permanent magnet is damaged by buckling or the like. An object of the present invention is to provide a permanent magnet type brushless DC motor which eliminates fear.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a brushless permanent magnet type comprising: a rotor having permanent magnets fixed in long holes formed at equal intervals in a circumferential direction; and a stator having magnetic poles wound with stator coils. In the DC motor, the long hole of the rotor is formed wider in the circumferential direction than the permanent magnet,
Voids are provided on both sides in the circumferential direction of the permanent magnet loaded in these long holes, both ends of the non-magnetic metal pipe inserted into these voids are projected beyond the permanent magnet, and these projected ends are plastically deformed. Thus, a permanent magnet type brushless DC motor is characterized in that a permanent magnet is fixed in the elongated hole.

The motor may be an inner rotor type or an outer rotor type. The rotor has a structure in which a magnet bush made by laminating a thin sheet of electromagnetic steel sheet is pressed and fixed on the outer circumference (inner rotor type) or the inner circumference (outer rotor type) of an aluminum drum made of a magnetic material such as an iron-based material. The hole can be loaded with a plate-shaped permanent magnet and fixed with a metal pipe. The metal pipe used here is preferably a stainless steel pipe. As a method of plastically processing the both ends of the pipe, a method of caulking or crushing can be used.

[0010]

FIG. 1 is a longitudinal sectional view of a wheel-in motor according to an embodiment of the present invention, FIG. 2 is a front view of a stator of the motor alone, FIG. 3 is a rear view thereof, and FIG.
IV line sectional view, FIG. 5 Exploded perspective view for explaining the procedure of assembling the stator, FIG. 6 is an exploded perspective view showing the structure of the bobbin and the stopper, FIG. 7 is a front view (A) and side sectional view of the magnet bush of the rotor. FIG. 8B is a partially enlarged view of a magnet bush, FIG. 9 is a view showing a method of loading a permanent magnet,
FIG. 10 is a diagram illustrating a method of caulking a pipe.

In FIG. 1, reference numeral 10 denotes a three-phase permanent magnet type brushless DC motor, which is housed in a motor case 12 which is divided into right and left parts. A special oil is put in the motor case 12, and the motor 10 is immersed in the oil to operate. The motor case 12 includes a right case half 12a fixed to a vehicle body (not shown) and a left case half 12b fixed to the right case half 12a in a liquid-tight manner.
With

An axle 14 is rotatably held by bearings 16 and 18 on the left case half 12b. The left end of the axle 14 projects from the left case half 12b, and the wheel 20 is mounted here. The wheel 20 is formed by a disc 20a and a rim 20b. A hub 22 is spline-coupled to the axle 14, and a disk 20a of the wheel 20 is bolted to the hub 22. Rim 20b
Is mounted with a tire (not shown).

An oil seal 24 is mounted between the left case half 12b and the boss of the hub 22 to prevent oil in the motor case 12 from leaking. Also hub 2
2, a brake drum portion 26 is formed integrally, and a brake shoe 30 is held on a pin 28 implanted in the left case half 12b. As a result, a well-known in-expandable drum brake that generates a braking force by pressing the brake shoe 30 against the drum portion 26 from the inside is formed.

The motor 10 is of an inner rotor type and has a stator 32 fixed to the right case half 12a and a rotor 34 rotating inside the stator 32. The rotor 34 has a drum shape and houses a planetary gear type speed reducer 36 inside thereof. Both ends of a shaft (rotor shaft) 38 integral with the rotor 34 are supported by bearings 40 and 42 on the inner surface of the right case half 12a and the axle 14, respectively.

The speed reducer 36 includes a ring gear 36a fixed to the inner surface of the left case half 12b, a sun gear 36b formed on the rotor shaft 38, and a plurality of planetary gears 36c meshing with the ring gear 36a and the sun gear 36b. have. A planet gear shaft 36d holding the planet gear 36c is fixed to a disk 14a integrally formed with the axle 14. As a result, the rotation of the rotor 34 is transmitted from the sun gear 36b to the planet gear 36c, and the planet gear 36c rotates around the sun gear 36b inside the ring gear 36a.
Therefore, the rotation of the rotor 34 is decelerated and transmitted to the axle 14.

The rotor 34 is press-fitted and fixed to an outer periphery of an aluminum drum 34a with an annular magnet bush 34b formed by laminating thin sheets of electromagnetic steel slope.
A plurality of (for example, 12) plate-like permanent magnets 36c are fixed at predetermined intervals to 6b. These permanent magnets 36c are magnetized so that the polarity alternates in the circumferential direction. The permanent magnet 36c is preferably a magnet having a high magnetic flux density, for example, a neodymium / iron / boron magnet. The method of fixing the permanent magnet 36c will be described later.

Next, the stator 32 will be described. Stator 3
The second stator core 44 is of a split type, in which an annular stator inner 46 and an annular stator outer 48 are fitted. Here, the stator inner 46 and the stator outer 48 are formed by laminating thin electromagnetic steel plates. As shown in FIG. 5, the stator inner 46 has a structure in which a number (for example, 18) of magnetic poles 50 projecting radially outward are connected in an annular shape on the inner diameter side. The stator outer 48 is annular as shown in FIG. 5, and can be fitted to the outer peripheral end of the magnetic pole 50 of the stator inner 46.

Before fitting the stator outer 48 to the stator inner 46, as shown in FIG.
2 is attached to each magnetic pole 50. After the bobbin 52 is mounted in this manner, the stator outer 48 is shrink-fitted and press-fitted as shown in FIG. Here, the bobbin 52 will be described.

The bobbin 52 is made of an insulating resin and is formed in a square thread shape as shown in FIG. That is, the flanges 56 and 58 are formed at both ends of the rectangular tube portion 54 in which the magnetic pole 50 is fitted. One of the flanges 58, that is, the magnetic pole 5
A locking claw 60 is formed integrally with the flange 58 disposed on the outer peripheral end side of the stator core 46 so as to protrude from the magnetic pole 50 in the outer diameter direction along the upper surface or the lower surface of the stator core 46.

A guide groove 62 (FIG. 6) is formed in the bobbin 52 along the inside of the rectangular tube portion 56 facing the locking claw 60. A metal stopper 64 is provided in the guide groove 62.
Can be inserted. The stopper 64 is L as shown in FIG.
It is made of a metal plate bent in a letter shape, and its tip side 64 a can be inserted into the guide groove 62. This tip side 64a
A claw-shaped protrusion 64b is formed on each of the left and right edges.
These projections 64b bite into the guide groove 62 when the distal end side 64a is inserted into the guide groove 62, and prevent the stopper 64 from dropping off.

On the inner surface of the rectangular tube portion 54 of the bobbin 52, an appropriate number of convex portions 66 (FIG. 6) are formed. When the bobbin 52 is mounted on the magnetic pole 50, these convex portions 66
0, and has a function of firmly fixing the bobbin 52 to the magnetic pole 50.

The stator 32 is assembled as follows.
First, the stator coil 68 is wound around the bobbin 52. The bobbin 52 around which the stator coil 68 is wound is positioned and mounted on the magnetic pole 50 such that the locking claw 60 is positioned on one surface (the lower surface in FIG. 5) of the stator inner 46. At this time, the locking claw 60 protrudes outward from the outer peripheral end of the magnetic pole 50 (step in FIG. 5).

Next, the stator outer 48 is mounted. That is, the stator outer 48 is moved axially (downward) from the plane (upper surface in FIG. 5) opposite to the plane of the stator inner 46 where the locking claws 60 of the bobbin 52 mounted on the magnetic pole 50 are located. The inner peripheral surface of the outer 48 is
0 and press-fitted to the outer peripheral end (step of FIG. 5). At this time, shrink fitting may be used. If the stator outer 48 is correctly fitted to the stator inner 46, the fitting portions 70 of the both will come into contact with the locking claws 60 of the bobbin 52 and positioned.

Next, the stopper 64 is mounted (step in FIG. 5). The stopper 64 is fitted into the guide groove 62 of the bobbin 52 along the surface (the upper surface in FIG. 5) of the stator outer 48 on the side opposite to the locking claw 60. The protrusion 64b of the stopper 64 bites into the inner surface of the guide groove 62,
The stopper 64 is prevented from being detached. At this time, the stopper 64 is engaged with the fitting portion 70 between the stator inner 46 and the stator outer 48.
It is fixed at the position crossing the top. As a result, the fitting portion 70
Are sandwiched between the locking claws 60 and the stoppers 64 to prevent the stator outer 48 from falling off the stator inner 46 in the axial direction.

A wiring board 72 is further mounted on the stator 32 thus assembled (step of FIG. 5). The wiring substrate 72 is annular as shown in FIGS. 2 and 5, and has seven locking holes 74 that are wide in the circumferential direction near the outer periphery (FIG. 2). The stopper 64 is
The stoppers 64 are not mounted on the bobbins 52 at positions corresponding to the locking holes 74, and the other eleven bobbins 52 are not mounted.

The wiring board 72 has a stopper 64
Is mounted on the stopper 64 such that the upright portion 64c (see FIG. 6) of the first member enters. The upright portion 64c of the stopper 64 projects through the locking hole 74 of the wiring board 72,
By mounting the solder on the protruding end, the wiring board 72 can be fixed to the stopper 64.

In this embodiment, the stator coil 68
U-, V-, and W-phase currents having a phase difference of 120 ° in electrical angle from each other are sequentially supplied to three stator coils 68 which are excited by the phase alternating current and are circumferentially adjacent to each other. Therefore, as shown in FIG. 2, annular bus bars 76 (76U, 76V, 76W) corresponding to the U, V, and W phases are attached and riveted to the wiring board 72, and these bus bars 76 are provided.
Is connected to a wiring pad facing a notch groove 78 (78U, 78V, 78W) provided on the outer periphery of the wiring board 72 via an inner layer circuit of the wiring board 72. In FIG. 2, the bus bar 7
An inner layer circuit connecting the groove 6 and the notch groove 78 is simplified and shown by a broken line.

The three adjacent stator coils 68 constitute a set, and one end of each of the three coils 68 has a notch groove 78 (78U, 78V, 7V) near each coil 68.
8W) and soldered. The other ends of the set of three coils 68 are assembled as shown in FIG. 3 and soldered together. This soldered portion is covered with an insulating material 80 (FIG. 3).

The ends of the coil 68 assembled and covered with the insulating material 80 are introduced directly from the bobbin 52 into the collecting portion (inside the insulating material 80) in FIG. In this case, there is a problem that the end of the coil 68 is easily unraveled from the bobbin 52 and the coil 68 is easily loosened. In order to solve this problem, a pair of notches 82 and 84 and an eave portion 86 located between the notches 82 and 84 are preferably provided on the flange 58 as shown in FIG. In this case, the terminal of the coil 68 is guided from one notch 82 to the other notch 84 under the eaves 86. In this way, the ends of the coil 68 are securely held by the eaves 86 and the notches 82, 84. As a result, the coil 68 does not loosen even when severe vibration is applied.

The wiring board 72 is integrally formed with wiring terminals 88 and 90 of a temperature sensor (not shown). In this embodiment, a temperature sensor such as a thermistor for detecting the temperature of the stator 32 is attached, and the leads of the temperature sensor are connected to these terminals 88 and 90.

The stator 32 thus assembled is
As shown in FIG. 1, the right case half 12 of the motor case 12
It is fixed inside a. That is, the bolt 32 is passed through three bolt holes 48a (FIGS. 2, 3, and 5) provided in the stator outer 48, and the bolt 32 is screwed into the right case half 12a to fix the stator 32. In FIG. 1, reference numeral 94 denotes a wiring plug mounted in a liquid-tight manner on the right case half 12a. The wiring passing through the wiring plug 94 is connected to the bus bar 76 (76U, 76V, 76B) of the wiring board 72.
W) terminals and temperature sensor terminals 88 and 9
Connected to 0.

Reference numeral 96 denotes an angle sensor attached to the right case half 12a. On the back surface of the drum 34a of the rotor 34 (the surface opposite to the speed reducer 36), a convex portion 98 is provided so as to correspond to every other angular position of the permanent magnet 34c. The rotor 3 is detected by detecting
4 is determined.

According to the three-phase brushless DC motor 10, a controller (not shown) determines the rotation angle of the rotor 34 based on the output of the angle sensor 96, and U, V, W corresponding to the rotation angle. Vary the phase current. As a result, the rotor 34 rotates. The drive torque is changed by, for example, performing phase shift control on the U, V, and W phase currents.

Next, a method of fixing the permanent magnet 34c to the rotor 34 will be described with reference to FIGS. An elongated hole 100 that is wide in the circumferential direction is formed in the magnet bush 34b. That is, a large number of thin plates forming the magnet bush 36b are formed by press punching.
The long holes 100 are formed by laminating thin plates that have been processed corresponding to 00.

The circumferential width of the long hole 100 is larger than the width of the permanent magnet 34c.
4c, the gap 1 is provided on both sides of the permanent magnet 34c.
02 and 102 are formed (see FIG. 8). 7 and 8
Reference numeral 104 denotes a half pierce, which is formed with a convex portion (concave portion) when a thin plate is subjected to press punching, and when the thin plates are laminated, the convex portion (concave portion) is formed as a concave portion (convex portion) of an adjacent thin plate. Has the function of aligning and joining the thin plates together.

Stainless steel pipes 106, 106 are inserted into gaps 102, 102 formed on both sides of the permanent magnet 34c when the permanent magnet 34c is loaded in the elongated hole 100. The pipe 106 has substantially the same diameter as the gap 102, and is longer than the length of the permanent magnet 34c (the length in the rotation axis direction of the rotor 34). Therefore, both ends of the pipe 106 protrude beyond the permanent magnet 34c. In this state, the permanent magnet is fixed in the long hole 100 by plastically deforming both ends of the pipe 106.

In order to plastically deform both ends of the pipe 106, it is only necessary to crimp or crush it. For example, as shown in FIG. 10, a block 108 for setting the height of the permanent magnet 34c on the lower surface 108 of the flat base 108 by touching the lower surface of the permanent magnet 34c.
a, and punches 108b, 108 for expanding the lower ends of the pipes 106, 106 by caulking. And this lower stand 1
08, the permanent magnet 34c and the pipes 106, 106 are aligned, while the other punches 110, 110 are applied to the upper ends of the pipes 106, 106 to make the punches 110, 11
Just hit 0 down.

As a result, the upper and lower ends of the pipes 106, 106 are enlarged in diameter as shown in FIG. 10, and this enlarged diameter portion engages the inner surface of the gap 102 with the edge of the permanent magnet 34c.
Is firmly fixed in the long hole 100. In this embodiment, both ends of the pipe 106 are caulked by the punches 108b and 110, but the permanent magnet 34c may be fixed to the long hole 100 by crushing with another tool. Further, a small amount of an adhesive or the like may be used in combination.

[0039]

As described above, according to the present invention, nonmagnetic metal pipes are inserted into the gaps formed on both sides in the circumferential direction of the permanent magnet, and both ends of these pipes are plastically deformed by caulking or crushing. In this case, the permanent magnet is fixed in the long hole of the rotor, so that a heating and drying device is required as in the case of fixing with an adhesive, and processing such as removal of excess adhesive is required. There is no. This simplifies the processing steps. Further, unlike the case where the permanent magnet is press-fitted into the long hole, a large load is not applied to the permanent magnet, so that the permanent magnet is hardly damaged.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention.

FIG. 2 is a front view of a stator of the motor alone.

FIG. 3 is a rear view of the same.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is an exploded perspective view showing a procedure for assembling the stator.

FIG. 6 is a perspective view showing a bobbin and a stopper.

FIG. 7 is a front view (A) and a side sectional view (B) of a magnet bush of the rotor.

FIG. 8 is a partially enlarged view of a magnet bush.

FIG. 9 is a diagram showing a method of loading a permanent magnet.

FIG. 10 is a diagram illustrating a method of caulking a pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Three-phase brushless DC motor 12 Motor case 32 Stator 34 Rotor 34a Rotor drum 34b Magnet bush 34c Permanent magnet 44 Stator core 46 Stator inner 48 Stator outer 50 Magnetic pole 52 Bobbin 68 Stator coil 100 Long hole 102 Air gap 106 Pipe 108 Lower stand 108b, 110 Punch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 29/06 H02K 29/06 Z F term (Reference) 5H002 AA07 AA08 AB07 AC09 AE08 5H019 AA10 BB01 BB04 CC03 CC04 CC09 DD01 DD10 EE09 EE10 EE14 5H621 BB10 GA01 GA04 GB10 GB14 HH01 5H622 CA02 CA05 CB03 DD02 PP03 PP12

Claims (4)

[Claims] 1. A permanent magnet brushless DC comprising: a rotor having permanent magnets fixed in long holes formed at equal intervals in a circumferential direction; and a stator having magnetic poles wound with stator coils.
In the motor, the long holes of the rotor are formed wider in the circumferential direction than the permanent magnets, voids are provided on both sides in the circumferential direction of the permanent magnets loaded in the long holes, and a nonmagnetic metal material inserted into these voids is provided. A permanent magnet brushless DC motor, wherein both ends of a pipe protrude from the permanent magnet, and the protruding ends are plastically deformed to fix the permanent magnet in the elongated hole. 2. A rotor made of a magnetic material, an annular magnet bush formed by laminating thin magnetic steel plates press-fitted and fixed to the drum, and a metal pipe loaded into an elongated hole formed in the magnet bush and fixed. The permanent magnet brushless DC motor according to claim 1, further comprising a plate-shaped permanent magnet formed. 3. The permanent magnet brushless DC motor according to claim 1, wherein the metal pipe is a stainless steel pipe. 4. The permanent magnet brushless DC motor according to claim 1, wherein both ends of the metal pipe are caulked to fix the permanent magnet in the elongated hole.