JPH09215235A - Brushless dc motor and holding method for its permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a brushless DC motor in which the latitude of an increase in costs due to a change in the shape of every permanent magnet can be suppressed to be small by a method wherein, when the permanent magnet is buried into every insertion part at a rotor core, a filler is filled into a gap between the magnet and the core so as to hold the permanent magnet and an identical core mold can be used even when the width size of the magnet is changed. SOLUTION: The size in the circumferential direction of every insertion part 43 is set to be larger than the size in the circumferential direction of every permanent magnet 44, and gaps which are extended in the axial direction are formed respectively on both sides in the circumferential direction of every magnet 44. In addition, solder pieces 48, 48 which are solidified in a heated and molten state so as to be filled at least partly in the axial direction of the gaps are arranged in the gaps, and every magnet 44 is held by the solder pieces 48, 48.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an embedded brushless DC motor in which a permanent magnet is embedded in each insertion portion of a rotor core, and a permanent magnet holding method for the same. Measures for common use of rotor core molds when changing the size of the rotor in the circumferential direction).

[0002]

2. Description of the Related Art Brushless DC motors are roughly classified according to a permanent magnet holding structure in a rotor.
0, a surface type having permanent magnets (b), (b), ... Arranged on the outer peripheral side of the rotor core (a), and FIG.
As shown in FIG. 4, the permanent magnets (b), (b), ... Are embedded in the insertion portions (c) of the rotor core (a), respectively. Comparing the two, the surface type is reinforced by shrink-fitting the stainless steel pipe (d) on the outer peripheral side in order to prevent the magnet (b) from peeling off due to the centrifugal force due to the rotation of the rotor. There is a need. On the other hand, in the case of the embedded type, there is no fear of such peeling of the magnet (b), and therefore, the magnet (b) is provided in each insertion portion (c) of the rotor core (a). All you have to do is press fit.

In practice, however, the magnet (b) is a sintered product similar to a seto product, is brittle, and has a large dimensional tolerance, so that the contact portion with the wall surface of the insertion portion (c) during press fitting is chipped. And easily scratched. Further, when the surface of the magnet (b) is coated for rust prevention and the like, the coating is easily peeled off. Further, when the magnet (b) is press-fitted, each laminated plate constituting the rotor core (a) is deformed unevenly so as to bulge outward in the radial direction,
As a result, unevenness is generated on the side peripheral surface of the rotor core (a), resulting in magnetic noise and torque ripple.
In order to avoid these problems, a process such as polishing is required to improve the dimensional tolerance of the permanent magnet (b), but such a separate process causes a significant cost increase. Therefore, in the case of the embedded type, the magnet (b) whose dimensional tolerance is not improved can be inserted and held in the insertion portion (c) without causing the above-mentioned problems. Ingenuity is required.

Therefore, conventionally, for example, Japanese Patent Laid-Open No. 5-83
As described in Japanese Patent Publication No. 892, a groove having a U-shaped cross section, which is open to the insertion portion and extends in the axial direction, is provided at a position on the inner peripheral side of each insertion portion of the rotor core, and After inserting a permanent magnet into the groove, a resin material is injection-molded in the groove, and the resin material is filled in a gap between the permanent magnet and the rotor core to be cured, thereby Despite variations due to dimensional tolerances, it can be inserted and held in the insertion portion without press fitting.

[0005]

Generally, in the rotor core, a large number of laminated plates punched into a predetermined shape by a core die are laminated in the axial direction of the rotor to be integrated. It is formed by Therefore, when the cross-sectional shape of the permanent magnet is changed, it is necessary to change the shape of the laminated plate accordingly, so that a new core die must be manufactured at high cost.

At this time, in the above-mentioned conventional example, since the resin material is injected into the gap between the permanent magnet and the rotor core, the cross-sectional shape of the insertion portion is made larger than the cross-sectional shape of the permanent magnet in advance. In this case, the cross-sectional shape of the permanent magnet can be dealt with by increasing / decreasing the injection amount of the resin material, so that the same core mold can be used and a large increase in cost can be avoided.

However, in the above-mentioned conventional example, since the groove for resin material injection is located in the radial direction (magnetic pole direction) between the permanent magnet and the rotor core, the groove increases the magnetic resistance. There is a problem that the main magnetic flux tends to decrease. If it is attempted to compensate for this decrease in magnetic flux, a larger magnet is required, and as a result, costs are increased.

The present invention has been made in view of the above points, and its main purpose is to provide an embedded brushless DC motor in which permanent magnets are embedded in respective insertion portions of a rotor core. When filling the gap between the magnet and the rotor core with the filling material to hold the permanent magnet, reviewing the filling position reduces the main magnetic flux when the width dimension of the permanent magnet is changed. The purpose is to allow the same core mold to be used without inviting, so that the increase in cost associated with the change in shape of the permanent magnet can be suppressed.

[0009]

In order to achieve the above object, in the present invention, the circumferential dimension of the insertion portion is made larger than the width dimension of the permanent magnet, so that the width dimension of the permanent magnet can be reduced. While making it possible to respond to changes, by interposing a filler in the gaps formed on both sides in the circumferential direction of the permanent magnet, the permanent magnet can be placed in the insertion portion regardless of variations in its width dimension and variations due to dimensional tolerances. I was able to hold.

Specifically, in the invention of claim 1, as shown in FIG. 2, the stator winding portion (33) is attached to the stator core (32).
And a stator (31) having a substantially cylindrical shape in which the rotor core (42) is rotatably arranged in the stator (31). As shown in FIG. The plate-shaped permanent magnets (44), (44), ... Are embedded in a plurality of insertion portions (43), (43) ,. A brushless DC motor with a rotor (41)

Then, as shown in FIG. 1 and FIG. 6, the dimension of each insertion portion (43) in the circumferential direction is set to be equal to that of each permanent magnet (4).
By making the dimension 4) larger in the circumferential direction, gaps extending in the axial direction are formed on both sides of the permanent magnets (44) in the circumferential direction. Then, in each of the gaps, a non-magnetic filler (48) that is solidified in a molten state so as to fill at least a part of the gap in the axial direction is arranged. ),
The permanent magnets (44) are held in the respective insertion portions (43) by (48), ....

In the above structure, the rotor core (42)
A permanent magnet (44) in each insertion part (43) of
With the (44), ... Inserted, a pair of gaps extending in the axial direction are formed between the permanent magnets (44) and the rotor core (42) on both sides in the circumferential direction. There is.
Therefore, variations in the width dimension of the permanent magnet (44) and variations due to dimensional tolerances are absorbed by the gaps on both sides,
When the width dimension of the permanent magnet (44) is changed, the same core mold can be used, and the increase in cost associated with the change in shape of the permanent magnet (44) can be suppressed to that extent.

On the other hand, a filler (48) which is solidified in a molten state so as to fill at least part of the gap in the axial direction is arranged in each of the gaps. Therefore, each of the permanent magnets (44) has the filler (48), regardless of the variation in the width dimension and the variation due to the dimension tolerance.
(48), ..., It is held in the insertion part (43).

At this time, the fillers (48), (4
Since 8), ... Are located in the gaps on both sides in the circumferential direction of each permanent magnet (44), there is a conventional radial gap (groove) between the permanent magnet (44) and the rotor core (42). Need not be provided, and a decrease in the main magnetic flux due to an increase in magnetic resistance due to such a gap does not occur. Therefore, in order to compensate for such a decrease in the main magnetic flux, a larger permanent magnet is required, resulting in no increase in cost. And the above-mentioned filler (48)
Since is a non-magnetic substance, the performance and demagnetization proof strength do not decrease due to the arrangement of the filler (48).

Further, the fillers (48), (48), ...
Is filled in the circumferential gap between the permanent magnet (44) and the rotor core (42), the permanent magnet (4 when the DC motor (30) is started, stopped, or when the load suddenly changes.
4) The wobble in the circumferential direction of 4) is suppressed by each filler (48), and the permanent magnet (44) caused by such wobble.
Will be less damaged. Further, when the permanent magnet (44) is inserted, it is not necessary to press the magnet (44) with a large force in spite of the shape change and the variation due to the dimensional tolerance. Missing or scratched,
The generation of magnetic noise and torque ripple due to the deformation of the rotor core (42) is avoided, and the insertion operation itself is facilitated.

Regarding the radial holding of the permanent magnets (44) in the respective insertion portions (43), the filler (4)
8), (48), etc., the permanent magnets (44) are rotated by the centrifugal force generated by the rotation of the rotor (41) during the operation of the motor (30) to cause the rotor core (42) to rotate. On the other hand, since it is pressed outward in the radial direction, there is practically no problem.

According to a second aspect of the present invention, in the first aspect of the present invention, the fillers (48), (48), ... Are melted by being heated and solidified by being cooled (for example, , Solder, etc.).
In the above structure, the fillers (48), (48), ...
Is melted by being heated and solidified by being cooled, so that the fillers (48), (48), ...
The melting and solidifying action of is carried out specifically and efficiently.

According to a third aspect of the present invention, as a permanent magnet holding method for a brushless DC motor according to the second aspect of the present invention, as shown in FIGS. Fillers (48), (48), ... Provided in a shape that can be inserted into the gap are used. Then, after interposing the fillers (48), (48), ... In the respective gaps, the rotor core (42) is heated to melt the fillers (48), (48) ,. To do so. In the above structure, the fillers (48), (4
Since 8), ... Are melted after being interposed in the respective gaps, workability is improved as compared with the case where the molten fillers (48), (48) ,. Will improve. In addition, in this case, the filler (48),
(48), ... Do not have to form one lump in each gap before the melting, and may be, for example, a plurality of small pieces, granules, powder or the like.

According to the invention of claim 4, in the invention of claim 3, as shown in FIGS. 8 and 9, a rotor (41)
When the rotary shaft (8) is fitted and fixed to the shaft center portion (41a) of the rotary shaft by shrink fitting, the melting temperature is lower than the shrink fitting temperature of the rotary shaft (8). Fillers (48), (48), ... Are used. And
By heating the rotor (41) to the shrink fitting temperature, the fillers (48), (48), ... Are melted. In the above structure, the fillers (48), (4
8), ... Are melted by heating performed on the rotor (41) when shrink-fitting the rotating shaft (8) on the rotor (41). Therefore, since a dedicated heating step and heating means for melting the fillers (48), (48), ... Are unnecessary, an increase in man-hours and equipment is suppressed, and the shape of the permanent magnet (44) can be changed. The cost increase associated with this can be further suppressed.

According to a fifth aspect of the present invention, in the above third aspect of the invention, as shown in FIG. 6, the permanent magnets (44) are moved in the circumferential direction while being interposed in the gaps on both sides of each permanent magnet (44). The fillers (48), (4
8), ... are used. Then, the filler (4
While the movement of each permanent magnet (44) in the circumferential direction is restricted by 8), (48), ..., The filling materials (48), (4)
8), ... are made to melt. In the above-mentioned structure, before the fillers (48), (48), ... Are melted, the respective permanent magnets in the respective insertion parts (43) by the fillers (48), (48) ,. Positioning of (44) in the circumferential direction is performed. Therefore, when the permanent magnets (44) are to be held by the fillers (48), (48), ..., No dedicated means for positioning the permanent magnets (44) in the circumferential direction is required. Therefore, the increase in cost associated with the change in shape of the permanent magnet (44) can be further suppressed.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the overall structure of a compressor for a refrigerant circuit that incorporates a brushless DC motor (30) according to an embodiment of the present invention. The compressor is installed in a refrigerant circuit (not shown) to compress the refrigerant. It is used for discharging.

In FIG. 2, (1) is a casing provided in the shape of a closed cylinder extending in the vertical direction, and a discharge pipe (2) communicating between the inside and outside of the casing (1) is provided at the upper end of this casing (1). The inner end of the casing (1) is positioned in the center of the upper end of the casing (1) and is inserted in an airtight manner.

A compression mechanism (3) for sucking the refrigerant gas, compressing it, and then discharging it into the casing (1) is fitted in the lower portion of the casing (1). The compression mechanism (3) is hermetically sealed between three disk-shaped side housings (4), (4), ... Which are arranged side by side in the vertical direction, and the side housings (4), (4) ,. It is provided with a housing portion composed of two annular annular roller housings (5), (5) which are sandwiched, and as shown in FIG. 3, each roller housing (5) has a cylindrical roller (6). ) Is located between the adjacent side housings (4), (4).

The side housings (4), (4), ...
A crankshaft (8) extending in the vertical direction is pierced in a central portion of the airtightly in an airtight manner. The crankshaft (8) has a circular cross-section that is eccentric from the center of its rotation,
It has a pair of eccentric parts (8a) and (8a). At that time, the eccentric portions (8a) and (8a) are eccentric in opposite directions with the axis of rotation interposed therebetween. Each of the rollers (6) is externally fitted to each of the eccentric parts (8a) so as to be rotatable around the eccentric axis of the eccentric part (8a), and the outer peripheral surface of the roller housing (5), The crankshaft (8) revolves around the axis of rotation while being in contact with the inner peripheral surface of (5).

A concave groove portion (5a) extending in the vertical direction is formed at a predetermined portion of the inner peripheral surface of each roller housing (5). A cylindrical rocking shaft (9) having a blade fitting insertion portion (9a) which is diametrically penetrated and extends in the vertical direction and which is cut out in a slit shape is provided in the concave groove portion (5a). It is rotatably supported with a heart. On the other hand, on the outer peripheral surface of each roller (6), a plate-shaped blade (1
0) is integrally projected. This blade (10)
Is fitted into the blade fitting portion (9a) of the swing shaft (9) and is held slidably in the fitting direction, which allows the rollers (6) to revolve around the orbital motion. The blade (10) is swung about the axis of the swing shaft (9). The blade (10) surrounds the outer peripheral surface of each roller (6), the inner peripheral surface of each roller housing (5), and the side housings (4) and (4) on both upper and lower sides, and has a crescent cross section. Space (1
1) is divided into two working chambers (12) and (12).

In the roller housing (5), an inlet port (13) and an outlet port (14) are opened on both sides in the circumferential direction with the groove (5a) (the position of the blade (10)) interposed therebetween. . The suction port (13) communicates with a downstream end of a suction pipe (15) that penetrates a side wall of the casing (1),
The upstream end of each suction pipe (15) has a casing (1).
Is connected to an accumulator (24) which is arranged laterally of and is integrally fixed to the casing (1). On the other hand, the outlet side of the discharge port (14) is opened inside the casing (1), and a discharge valve (16) as a check valve composed of a reed valve is arranged therein. In FIG. 3, (2
1) is a stopper that regulates the maximum opening of the discharge valve (16). The low-pressure refrigerant gas in the accumulator (24) is sucked into the suction pipe (1) by the revolution movement of each roller (6).
5) and the suction port (13), the suction gas is sucked into each working chamber (12), the refrigerant gas is compressed by the volume reduction of the working chamber (12) accompanying the revolving motion of the roller (6), and then the discharge port (1).
4) is discharged into the casing (1) to increase the internal pressure of the casing (1), and the high-pressure refrigerant gas in the casing (1) is discharged from the discharge pipe (2) to the outside of the casing (1). Has become. Although not shown, a safety device for terminating the operation of the compressor when the discharge temperature of the refrigerant gas reaches a predetermined value (for example, 150 ° C.) is arranged in the casing (1).

The outer peripheral surface of each eccentric portion (8a) of the crankshaft (8), the outer peripheral surface of the crankshaft (8) located above the upper eccentric portion (8a), and the lower eccentric portion (8a).
Lubricating oil discharge holes (17), (17), ... Are opened in each of the outer peripheral surfaces of the crankshaft (8) located on the lower side of the. Each lubricating oil discharge hole (17) is provided so as to pass through the axial center of the crankshaft (8), and the lower end thereof is open to the lower end surface of the crankshaft (8). Are in communication with each other. On the other hand, an oil sump (18) is provided at the bottom of the casing (1), and the lower end of the crankshaft (8) is immersed in the lubricating oil accumulated in the oil sump (18). It is done like this. Then, as the crankshaft (8) rotates, the centrifugal force is utilized to suck the lubricating oil in the oil sump (18) into the lubricating oil passage, and the lubricating oil discharge holes (17), (17),
Is supplied to the sliding portion of the compression mechanism (3). A part of the lubricating oil used for this lubrication is mixed with the refrigerant gas discharged into the casing (1) from the discharge port (14) of the compression mechanism (3) and then discharged.

A brushless DC motor (30) for driving the compression mechanism (3) is fitted in the upper part of the casing (1) with a vertical axis of rotation. This brushless DC motor (30) has a substantially cylindrical stator (31) fixed to the inner wall surface of the casing (1).
And a rotor (4) rotatably arranged in the stator (31) and rotatably connected to the crankshaft (8).
1) and are provided.

The stator (31) is a substantially cylindrical stator core (in which a large number of laminated plates are laminated and integrated in the axial direction of the DC motor (30) (vertical direction of the casing (1)). 32) and a stator winding portion (33) made up of three-phase windings arranged on the inner peripheral side of the stator core (32). The three-phase windings of the stator winding portion (33) have their one ends connected to each other to form a neutral point, while the other end of each winding serves as an input terminal. That is, the three-phase windings are Y-connected, and the stator (31) generates a rotating magnetic field by sequentially switching the voltage applied to the input terminal of each winding. In FIG. 2,
In (33a), the stator winding portion (33) has a stator core (3
It is a coil end protruding vertically from both upper and lower ends of 2). Further, (19) is a power source connecting portion attached to the outer surface of the upper end portion of the casing (1), and the power source connecting portion (19) includes three power source input lines connected to the respective windings and the respective windings. 4 terminals (20), (2) to which one signal output line connected to the neutral point is connected, respectively.
0), ... (In FIG. 2, only three terminals are visible). The signal output line is used for detecting the magnetic pole position in the rotation direction of the rotor (41) and so on.

On the other hand, as shown in FIG. 4, the rotor (41) includes a substantially cylindrical rotor core (42) formed by laminating a large number of laminated plates in the axial direction, and the rotor core (42). 42) four flat magnets (44), (4)
4), ... And. A pair of disc-shaped end plates (45), (45) are integrally joined to both axial end faces of the rotor core (42) by four fastening rivets (49), (49) ,. Has been done. In FIG. 4, (41b) is an insertion hole for each of the fastening rivets (49). Rotor (4
In the shaft center portion of 1), a shaft insertion hole (41
a) is formed, and the upper end portion of the crankshaft (8) is fitted and fixed in the shaft insertion hole (41a) by shrink fitting (shrink fitting temperature is 250 to 300 ° C., for example).

Further, on the peripheral portion of the rotor core (42), there are four insertion portions (4 having a rectangular slot-shaped cross section, each of which penetrates in the axial direction and extends in the direction orthogonal to the radial direction.
3), (43), ... Are arranged so as to form each side part of a square around the shaft insertion hole (41a), and the permanent magnet () is formed in each insertion part (43). 44), (44), ... Are embedded. further,
The rotor core (42) has a slit-shaped barrier portion (4) that penetrates the core (42) in the axial direction and extends radially outward from both sides of each insertion portion (43).
6), (46), ... Are provided. Each of the barrier portions (46) has a function of preventing a short circuit of magnetic flux in the rotor core (42).

At the upper end of the rotor (41) of the brushless DC motor (30), a disk-shaped oil separating plate (47) is integrally rotated by fastening the rivets (49), (49) ,. It is installed. This oil separation plate (47)
The rotor (41) is fixed at a predetermined distance upward from the upper end of the rotor (41), that is, in a state of facing the upper coil end (33a) of the stator winding portion (33), and is discharged from the compression mechanism (3). When the lubricating oil is discharged from the outlet (14) together with the discharge gas into the casing (1) toward the discharge pipe (2), the lubricating oil flows toward the discharge pipe (2) side so that the rotor (41). The oil separating plate (47) that rotates integrally with is used to prevent it.

In this embodiment, in the rotor (41) of the brushless DC motor (30) shown in FIG.
As shown in, the circumferential dimension of each of the insertion portions (43) is larger than the circumferential dimension of each of the permanent magnets (44). A gap extending in the axial direction is formed on each side of the circumferential direction. Then, in each of the gaps, a solder (48) as a non-magnetic filler, which is solidified in a heated and melted state so as to fill at least part of the gap in the axial direction, is arranged. Each of the permanent magnets (44) is held in each insertion portion (43) by the solders (48), (48) ,. The melting temperature of the solders (48), (48), ...
The shrink fitting temperature of the crankshaft (8) described above (in this case, 2
Lower than 50 to 300 ° C. and higher than the allowable temperature of the refrigerant gas (150 ° C. in this case) (for example, 180 to 1)
90 ° C).

Here, the permanent magnets (44), (44), and (44) are inserted in the respective insertion portions (43) of the rotor core (42).
A method of holding the ... Is described. First, as shown in FIG. 5 and FIG. 6, it is possible to insert into the gap extending from each barrier part (46) to the connection part with each insertion part (43), and in the insertion part (43) in the inserted state. Solders (48), (48), ..., Which are respectively provided in the shape of a flat plate, which can regulate the movement of the permanent magnet (44) in the circumferential direction, are used. Then, each permanent magnet (44) is inserted into each insertion portion (43),
Further, the solders (48), (48), ... Are inserted into the respective gaps, and the solders (48), (4
Positioning of each permanent magnet (44) in each insertion part (43) is performed by 8).

Next, as shown in FIG. 7, the rotor core (4
After the end plates (45) and (45) are joined to both end faces of 2) to obtain the rotor (41), the rotor (41) is cranked in a state in which its axial direction is the vertical direction. The shaft (8) is heated to a shrink fitting temperature of 250 to 300 ° C. As a result, each solder (48) melts so as to fill the lower part of the gap extending from each barrier part (46) to the connection part with each insertion part (43) as shown in FIG. . On the other hand, as shown in FIG. 8, the shaft insertion hole (41) of the rotor (41) is
The upper end of the crankshaft (8) is fitted and inserted into a) from below.

Then, by cooling the rotor (41), the solders (48), (48), ... Are solidified in close contact with the rotor core (42) and each permanent magnet (44). As a result, the permanent magnets (44) can be held in the insertion parts (43), while the crankshaft (8) is integrally rotated with the rotor (41) as shown in FIG. Connect and fix to. In the above description, the permanent magnet (44) is described as being inserted into the insertion portion (43), but the permanent magnet (44) is already magnetized at the stage of insertion. Alternatively, it may be magnetized by being applied to the stator winding portion (33) after being inserted. In particular, in the case of a magnet that generates a strong magnetic force such as a rare earth magnet, in consideration of workability at the time of insertion and contact with the rotor core (42) of the magnet (44), it is possible to magnetize after the insertion. desirable.

Therefore, according to this embodiment, in the embedded brushless DC motor (30), the permanent magnets (4) are provided in the respective insertion portions (43) of the rotor core (42).
4), (44), etc. are inserted, a pair of gaps extending in the axial direction on both sides in the circumferential direction of the respective permanent magnets (44) are formed between the permanent magnets (44) and the rotor core (42). Thus, it is possible to absorb variations in the width dimension of the permanent magnet (44) and variations due to dimensional tolerances by the gaps on both sides thereof. Therefore, when the width dimension of the permanent magnet (44) is changed, the same core mold can be used, and the width of the cost increase due to the change of the shape of the permanent magnet (44) can be reduced accordingly. Can be suppressed.

On the other hand, in each of the above-mentioned gaps, the solder (48) solidified in the state of being heated and melted so as to fill at least a part (the lower side in this example) of the gap in the axial direction,
Since (48), ... Are arranged, the permanent magnets (44) are inserted by the solder (48), (48), ... 43). In addition, since each solder (48) is heated and melted in a state of being interposed in each gap, the workability is improved as compared with the case where the molten solder (48) is poured into each gap. Can be significantly improved.

At this time, it is not necessary to provide a radial gap (groove) between the permanent magnets (44) and the rotor core (42) as described in the section of the prior art.
Such a gap does not cause a decrease in main magnetic flux due to an increase in magnetic resistance. Therefore, in order to compensate for such a decrease in the main magnetic flux, a larger permanent magnet is required, resulting in no increase in cost. Since the solder (48) is a non-magnetic material, the performance / demagnetization proof strength does not decrease due to the placement of the solder (48) as described above.

At this time, even if the permanent magnets (44) in the respective insertion portions (43) cannot be held in the radial direction by the solders (48), (48), ... Rotor (41) during operation of (30)
The permanent magnets (44) are pressed outwardly in the radial direction with respect to the rotor core (42) by the centrifugal force generated by the rotation of No. 1, so that there is no practical problem.

Further, the solders (48), (48),
Since the heat is applied to the rotor (41) by shrink-fitting the rotary shaft (8) on the rotor (41), the solder (48), ( 48),
It does not require a dedicated melting process and heating means for heating and melting ..., and can suppress an increase in man-hours and equipment,
Therefore, it is possible to further suppress the cost increase caused by changing the shape of the permanent magnet (44).

The solders (48), (48), ...
Before the solder is melted, the solder (48),
Since the permanent magnets (44) can be positioned in the circumferential direction in the insertion portions (43) by means of (48), ..., The permanent magnets (44) are soldered (48), (4).
8), ..., When holding by the permanent magnets (44), a dedicated means for positioning the permanent magnets (44) in the circumferential direction is unnecessary, and the cost associated with changing the shape of the permanent magnets (44) is correspondingly increased. It will be possible to further reduce the width of the up.

In addition, the solder (48), (48),
Are filled in the circumferential gap between the permanent magnet (44) and the rotor core (42), the DC motor (30)
It is possible to suppress the wobbling of the permanent magnet (44) in the circumferential direction at the time of startup, stop, sudden load change, etc., and reduce the damage to the permanent magnet (44) due to such wobbling. Further, when the permanent magnet (44) is inserted, it is not necessary to press the magnet (44) with a large force in spite of the shape change and the variation due to the dimensional tolerance. It is possible to avoid the occurrence of magnetic noise, torque ripple, and the like due to chipping or scratching of the core, or deformation of the rotor core (42), and the insertion operation itself can be facilitated.

In the above embodiment, each insertion portion (43)
On the other hand, solder (48), (48) with permanent magnet (44)
The permanent magnet (44) may be inserted first, or the solders (48), (48) may be inserted first.

In the above embodiment, the rotor core (4
The brushless DC motor (30) having the barrier portions (46), (46), ... In 2) has been described, but the present invention is applied to the brushless DC motor which does not have such barrier portions (46), (46) ,. Can also be applied.

Furthermore, in the above embodiment, the brushless DC motor (30) built in the compressor for the refrigerant circuit has been described, but the brushless DC motor (30) can be used in a device other than the compressor. Of course.

[0047]

As described above, according to the first aspect of the invention, in the embedded brushless DC motor in which the permanent magnets are embedded in the respective insertion portions of the rotor core, the circumference of the respective insertion portions is described. By making the dimension in the direction larger than the dimension in the circumferential direction of each permanent magnet, a gap extending in the axial direction is formed on each side of the permanent magnet in the circumferential direction. , Arranging a non-magnetic filler that is solidified in a molten state so as to be filled in at least a part of the gap in the axial direction, and holds the above-mentioned permanent magnets in their respective insertion parts by these filling members. Therefore, when the circumferential dimension (width dimension) of the permanent magnet is changed, the same core mold can be used without lowering the main magnetic flux, and the cost increase associated with changing the shape of the permanent magnet can be increased. Keep it small Can.

According to the invention of claim 2, the filler is
Since it is configured such that it is melted by being heated and solidified by being cooled, the effect of the invention of claim 1 can be obtained specifically and efficiently.

According to the third aspect of the present invention, as a permanent magnet holding method for the brushless DC motor according to the second aspect of the present invention, the filling is provided so that it can be inserted into the gaps on both sides in the circumferential direction of each permanent magnet. Since the fillers are used to interpose the fillers in the gaps, and the rotor core is heated to melt the fillers, when the molten fillers are poured into the gaps. Compared with this, workability can be improved.

According to the fourth aspect of the present invention, when the rotary shaft is fitted and fixed to the shaft center portion of the rotor by shrink fitting, the melting temperature is the shrink fitting temperature. Since the filler is lower than the above, and the filler is melted by the heating temperature at the time of shrink fitting, the melting step and heating means for heating and melting the above filler are unnecessary, and the increase in man-hours and equipment can be suppressed. Therefore, it is possible to further suppress the cost increase caused by changing the shape of the permanent magnet.

According to the fifth aspect of the present invention, the filler provided in the shape that restricts the movement of the permanent magnets in the circumferential direction while being interposed in the gap is used. Since the filler is melted in a state in which the movement is restricted, it is possible to eliminate the need for a dedicated means for positioning the permanent magnet in the circumferential direction when holding the permanent magnet in the insertion portion. Therefore, it is possible to further reduce the cost increase caused by changing the shape of the permanent magnet.

[Brief description of drawings]

FIG. 1 is a diagram showing a permanent magnet holding structure in a rotor core of a brushless DC motor according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II of FIG.

FIG. 2 is a vertical cross-sectional view showing a compressor for a refrigerant circuit having a built-in brushless DC motor.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is an exploded perspective view showing a configuration of a rotor of a brushless DC motor.

FIG. 5 is a perspective view showing a step of inserting a permanent magnet and solder into the insertion portion and the barrier portion of the rotor core.

FIG. 6 is a cross-sectional plan view showing a state in which a permanent magnet and solder are inserted in a rotor core.

FIG. 7 is a perspective view showing a heating step of a rotor.

FIG. 8 is a perspective view showing a step of fitting and fixing an upper end portion of a crankshaft into a shaft insertion hole of a rotor.

FIG. 9 is a perspective view showing a state in which a crankshaft is fitted and fixed to a rotor.

FIG. 10 is a cross-sectional view schematically showing a surface type brushless DC motor.

FIG. 11 is a cross-sectional view schematically showing an embedded brushless DC motor.

[Explanation of symbols]

 (30) Brushless DC motor (31) Stator (32) Stator core (33) Stator winding part (41) Rotor (41a) Shaft insertion hole (shaft center part) (42) Rotor core (43) Insertion part (44) Permanent magnet (48) Solder (filler)

Claims (5)

[Claims] 1. A stator winding portion (3) is attached to a stator core (32).
A substantially cylindrical stator (31) in which 3) is arranged;
A plurality of insertion parts (43), (4) rotatably arranged in the stator (31), each provided in the shape of a slot that penetrates the rotor core (42) in the axial direction and extends in the substantially circumferential direction.
3), ... Plate-shaped permanent magnets (44), (4)
4) is a brushless DC motor including a rotor (41) having embedded therein, and a dimension of each insertion portion (43) in the circumferential direction is set to each permanent magnet (4).
4) is larger than the circumferential dimension of the permanent magnets (44) to form axially extending gaps on both sides of the permanent magnets (44) in the circumferential direction, and at least a part of the gaps in the axial direction is formed in each of the gaps. A non-magnetic filler (48) that is solidified in a molten state so as to be filled in each is placed, and the permanent magnets (44) are replaced by the fillers (48), (4).
A brushless DC motor, characterized in that it is held in each insertion portion (43) by 8), .... 2. The brushless DC motor according to claim 1, wherein the fillers (48), (48), ... Are melted by being heated and solidified by being cooled. Brushless DC motor. 3. A brushless D according to the invention of claim 2.
A method for holding a permanent magnet of a C motor, comprising using fillers (48), (48), ... After the fillers (48), (48), ... Are interposed in the core, the rotor core (42) is heated to melt the fillers (48), (48) ,. A method for holding a permanent magnet of a brushless DC motor. 4. The method for holding a permanent magnet of a brushless DC motor according to claim 3, wherein the rotary shaft (8) is fitted and fixed integrally with the shaft (41a) of the rotor (41) by shrink fitting. And heating the rotor (41) to the shrink-fitting temperature using the fillers (48), (48), ... whose melting temperature is lower than the shrink-fitting temperature of the rotary shaft (8). A method for holding a permanent magnet of a brushless DC motor, characterized in that the fillers (48), (48), ... 5. The method for holding a permanent magnet of a brushless DC motor according to claim 3, wherein the permanent magnet (44) has a shape that restricts circumferential movement of the permanent magnet (44) in a state of being interposed in a gap between both sides of the permanent magnet (44). The provided fillers (48), (48), ... Are used while the movement of each permanent magnet (44) in the circumferential direction is restricted by the fillers (48), (48) ,. Four
8), (48), ... Are melted, and a permanent magnet holding method for a brushless DC motor is characterized.