JP2819978B2 - DC brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor used for driving a fan of an indoor air conditioner.

[0002]

2. Description of the Related Art Conventionally, an AC induction motor that changes the number of windings and changes the rotation speed has been used for driving such a fan. However, AC induction motors have drawbacks in that they are inefficient and do not satisfy the demand for energy saving, and that the size of the device is large. Therefore, in recent years, a DC brushless motor has begun to be used instead of an AC induction motor. As shown in FIG. 7, this DC brushless electric motor rotatably supports an output shaft 53 on a housing 51 via a bearing 52, and has a plurality of magnetic pole portions wound with coils.
3 is fixed integrally with the housing by a resin mold (see hatching in the figure) while a predetermined gap is provided between the stator 54 and a permanent magnet formed by magnetizing an annular magnet material to a plurality of poles. A rotor casing 57 in which the inside 58 is fitted and which is fitted outside the stator 54 with a gap is pressed into the knurled portion of the output shaft 53 at the center boss portion 57a. Then, when the plurality of magnetic pole portions of the inner stator 54 are sequentially excited, the outer permanent magnets 58 are successively attracted to the excited magnetic pole portions, and the rotor casing 57 rotates, and this rotation passes through the boss portion 57a. The output shaft 53 is transmitted to the output shaft 53 to rotate.

[0003]

Generally, a DC brushless motor has a structure in which a plurality of magnetic pole portions of a stator 54 are sequentially excited to attract and rotate a plurality of magnetic poles of a permanent magnet 58 of a rotor casing 57. Rotational unevenness called cogging at the switching position of each magnetic pole portion inevitably occurs. In order to reduce this cogging, in the conventional DC brushless motor described above, an annular and integral magnet material having a certain thickness is magnetized into a plurality of poles by changing the shape of the magnetizing yoke to a magnetizing force distribution such that cogging is reduced. doing. However, such a magnetization method has a drawback that work management is difficult, and the performance of the permanent magnet 58 after the magnetization varies widely. Further, in the above-described conventional DC brushless motor, since the magnetic flux generated at the magnetic pole portion does not become a sine wave due to the simplification of the structure of the stator 54, cogging also occurs in the stator 54 due to this. Since the cogging is integrally fixed in the housing 51 with a resin mold, the cogging is directly transmitted to the housing, and there is a disadvantage that vibration and noise of the electric motor increase.

In the above-described conventional DC brushless motor, the rotating output shaft 53 is supported at both ends by two bearings 52, 52 disposed on both sides of a stator 54 in a housing 51, specifically, on both ends in the housing 51. Therefore, when the motor is used for driving a fan or the like of an indoor air conditioner, there is a disadvantage that the size cannot be reduced if the size of the motor in the axial direction becomes large. Therefore, an object of the present invention is to
By devising the structure of the housing of the members in the housing and the structure of the output take-out part, the assembly is easy and the size can be reduced.
Moreover, it is an object of the present invention to provide a DC brushless motor that can reduce vibration and noise of the motor due to cogging.

[0005]

According to a first aspect of the present invention, there is provided a DC brushless electric motor, comprising: a mounting member fixed to a housing having an open front end; A central shaft 4 which does not protrude is provided, and a stator 7 is externally fitted to the central shaft 4 via a vibration-proof rubber cylinder 6 while a magnetic pole piece 40 made of a permanent magnet is provided on the stator 7 so as to have a predetermined shape. A rotor 8 fitted externally with a gap therebetween is rotatably mounted on the center shaft 4 via a support member 9, and the mounting member 3 is a bottomed cylinder having an open front end. At least three places in the circumferential direction of the cylindrical part 20 having a bottomed cylinder, penetrating 20a near the rear end from the center in the axial direction
On the other hand, between the outer peripheral surface of the cylindrical portion 20 of the bottomed cylinder and the inner peripheral surface of the housing 1, an anti-vibration rubber shell 2 having a projection 2 a fitted into the through hole 20 a is interposed. It is characterized by.

According to a second aspect of the present invention, the anti-vibration rubber shell 2 of the DC brushless motor according to the first aspect is provided such that the rear end 2c abuts on the rear end walls 12d and 16 of the housing 1 and the outer periphery of the front end. An annular groove 2b, in which an annular protrusion 14 provided on the inner periphery of the front end of the housing 1;
15 may be fitted. Further, as described in claim 3, the support member 9 of the DC brushless motor according to claim 1 or 2 is provided with a cylindrical portion 9a that accommodates a ball bearing 32 that is externally fitted to the center shaft 4, and a rear portion of the cylindrical portion 9a. And a vibration isolating rubber joint 10 for connecting to the center of the end of the driven body 43 on the outer periphery of the cylindrical portion 9a. You may.

[0007]

In the electric motor of the first aspect, the center shaft 4 is protruded from the mounting member 3 formed of a bottomed cylinder having an open front end, and the stator 7 is mounted on the center shaft 4 via the vibration-proof rubber cylinder 6. Have been. The outer peripheral surface of the bottomed cylinder 3 and the housing 1
The vibration-proof rubber shell 2 is interposed in an appropriate compressed state between the inner peripheral surface and the inner peripheral surface of the cylindrical member 20. Are respectively fitted in through holes 20a provided near the rear end from the center in the axial direction. Therefore, the cogging generated in the stator 7 at the time of driving is prevented from being transmitted to the central shaft 4 by the vibration-proof rubber cylinder 6 fitted therein, and the cogging transmitted to the bottomed cylinder 3 via the central shaft 4 is also reduced in the size of the motor. The transmission to the housing 1 is prevented by the vibration-proof rubber shell 2 which can contribute to the structure, and vibration and noise of the housing 1 due to cogging are effectively reduced. Also, since the bottomed cylinder 3 is fixed by fitting at least three projections 2a of the vibration-proof rubber shell 2 into the through-holes 20a, assembly and disassembly can be performed easily and with high accuracy, and the center of the shaft at the time of assembly can be reduced. Because there is no gap,
Even if a cross-flow fan with a long shaft is driven, noise and vibration are less generated. Further, since the through hole 20a is provided near the rear end, that is, near the bottom plate 19 of the bottomed cylinder 3, the through hole 20a has higher rigidity, is superior in strength, and generates vibration and noise as compared with the case where it is provided near the front end. Few.

According to the second aspect of the present invention, the anti-vibration rubber shell 2 of the first aspect of the present invention has the rear end 2c abutting against the rear end walls 12d and 16 of the housing 1 and the annular groove 2b formed on the outer periphery of the front end thereof. Are fitted to the annular projections 14 and 15 on the inner periphery of the front end of the motor, so that transmission of vibration and noise caused by cogging generated in the stator 7 to the center shaft 4 and the housing 1 is prevented, and assembly and disassembly are performed. , The prevention rubber shell 2 can be securely fixed in the axial direction, and the vibration and noise of the housing 1 are further reduced. In the electric motor according to the third aspect, the flange 9b of the support member 9 is fixed to the front end 8a of the rotor 8, and the ball bearing 3 housed in the cylindrical portion 9a in front of the flange 9b.
2 is fitted around the center shaft 4, and the outer periphery of the cylindrical portion 9 a and the center of the end of the driven body 43 are connected by a vibration-proof rubber joint 10. Therefore, the rotor 8 rotates smoothly, concentricity between the electric motor and the driven body 43 is ensured, and vibration and noise transmitted from the rotor 8 to the driven body 43 can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a cross-sectional view illustrating an example of a DC brushless motor used for driving a fan of an indoor air conditioner.

This DC brushless motor has an end bracket 3 as a bottomed cylindrical mounting member fitted and fixed to a vibration-proof rubber shell 2 mounted on the entire cylindrical inner peripheral surface of a housing 1, and an end bracket 3 Center hole 3a of bracket 3
A central shaft 4 protruded by press-fitting, a stator 7 having six magnetic pole portions, which are externally fitted and fixed to the central shaft 4 via a fixed seat 5 and an anti-vibration rubber cylinder 6; A rotor 8 fitted outside the stator 7 with a small gap, and a flanged cylindrical shape;
A bearing housing 9 is fixed to the front end plate 8a of the rotor by rivets 11 together with an anti-vibration rubber joint 10 to be fitted around, and the rotor 8 is rotatably mounted on the center shaft 4 as a support member. .

The housing 1 comprises a substantially half-cylindrical lower housing 12 as shown in FIG. 2 and a substantially half-cylindrical upper housing 13 as shown in FIG. As shown in FIG. 2, the lower housing 12 has a cylindrical inner peripheral surface 12 for housing the end bracket 3 (see FIG. 1) and the like.
The front end is an annular projection 14 (see FIG. 2C) slightly projecting radially inward. In order to fix the upper housing 13, rectangular holes 12 are formed on both sides of the upper surface.
b and a female screw hole 12c are provided, and a pair of knock pins 12e are provided on the upper surface of the rear end wall 12d. As can be seen from FIG. 2C, the lower housing 12 is formed of a resin molded product in which a bent thin plate is reinforced with ribs, and the bottom thereof has a fan 43 (see FIG. 2) to be driven, as shown in FIG. 1) has the same bottom plate 17 as the bottom plate of the casing. On the other hand, as shown in FIG. 3, the upper housing 13 has a similar cylindrical inner peripheral surface 13a having an annular projection 15 at the front end (see FIG. 3 (C)). A rectangular projection 13b fitted into the rectangular hole 12b and a bolt through hole 13c, and a hole 13e for inserting the knock pin 12e into a flange at the lower end of the rear end wall 16.
(See FIG. 3A). A rectangular hole 16a (FIG. 3) through which a power cord (see FIG.
(See (B)).

As shown in FIG. 4, the anti-vibration rubber shell 2 fitted to the inner peripheral surfaces 12a, 13a of the upper and lower housings 12, 13 has an integral cylindrical shape that is not divided into upper and lower parts, and has an axial center. Circular projections 2a are provided at four locations on the inner peripheral surface, which is closer to the front, up, down, left and right, and annular grooves 2b are provided on the outer periphery of the front end.
Then, the rear end 2c is connected to the rear end walls 12d, 16 of the upper and lower housings.
And the annular protrusion 1 of the upper and lower housings
4, 15 (see FIGS. 2 and 3 (C)) are fitted and fitted as shown in FIG. A rectangular notch 2d for a power cord is provided at the rear end of the side of the vibration-proof rubber shell so as to communicate with the rectangular hole 16a of the rear end wall 16 (see FIG. 1). Such an anti-vibration rubber shell 2 not only absorbs cogging, but also suppresses the swing of the driven fan 43 (see FIG. 1) and the failure of the rotor 8 while suppressing the increase in the radial dimension of the housing 1 as much as possible. It plays a role in suppressing the transmission of vibration and noise to the housing 1 due to the balance and the improper squareness of the stator 7 and the rotor 8 with respect to the center axis. Further, the integral cylindrical vibration-isolating rubber shell 2 is externally fitted to the end bracket 3 and the upper and lower housings 12 and 13 are fitted.
By fixing the vibration-proof rubber shell 2 in the radial direction and the axial direction of the housing 1 with high accuracy and reliability, it is possible to save the labor for assembly.

As shown in FIG. 5, a bottomed cylindrical end bracket 3 fitted to the vibration-proof rubber shell 2 has a bottom plate 19.
And a cylindrical portion 20. In the bottom plate 19, as shown in FIG.
a, six elliptical holes 19b around which the terminals 30 of the coil 29 of the stator 7 (see FIG. 1) pass, three rectangular holes 19c through which the Hall element 22 (see FIG. 1) passes above and outside, and the cylindrical portion 2
In the outermost circumference straddling 0, six fixing holes 19d, into which fixing springs 26 (see FIG. 1) for fixing the printed circuit board 21 are engaged,
Inside each engagement hole 19d, a small hole 19e for positioning a spacer 25 with vibration isolating rubber (see FIG. 1) sandwiched between the printed circuit board and the printed circuit board is provided. On the other hand, as shown in FIG. 5B, the cylindrical portion 20 is provided with circular through holes 20a at four positions in the upper, lower, left, and right directions in the circumferential direction near the rear end from the center in the axial direction. The circular projection 2a of the vibration rubber shell 2 is fitted as shown in FIG. This arrangement on the rear end side is for suppressing the vibration of the end bracket 3 due to cogging by providing the through hole 20a on the rear end side having the bottom plate 19 and high rigidity.

The outer diameter of the circular projection 2a and the inner diameter of the through hole 20a are set to optimal dimensions so that the end bracket 3 can be easily attached to and detached from the vibration-proof rubber shell 2 and that the transmission of cogging to the housing 1 can be reduced. Have been. The inner diameter of the housing 1, the thickness of the vibration-proof rubber shell 2, and the outer diameter of the end bracket 3 are such that when the upper and lower housings 12 and 13 are integrally fixed, the vibration-proof rubber shell 2 is separated from the housing 1 and the end bracket. 3 and is adjusted to a size that provides optimum compression to absorb vibration and noise most. In this manner, through holes 20a are provided at four places of the cylindrical portion 20 of the end bracket 3, and four circular protrusions 2a that fit into the through holes 20a are provided on the inner periphery of the integral cylindrical vibration-proof rubber shell 2. As a result, the center shaft 4 can be attached to the housing 1 at a high right angle and with a single touch, and the cross shaft with a long shaft length can be saved while reducing the assembling work as compared with a two-piece anti-vibration rubber shell. Noise and vibration can be reduced even when the flow fan 43 is driven.

A drive circuit for controlling the energization of the coil 29 of the stator 7 comprises a printed circuit board 21 fixed to the rear surface of the end bracket 3, as shown in FIG. The printed circuit board 21 includes a Hall element 22 and a driver IC 23
A rubber sheet 24 is sandwiched between the driver IC 23 and the printed circuit board 21 at one end, and a spacer 25 with vibration isolating rubber is sandwiched between the other end and the end bracket 3.
It is fixed to the end bracket 3 by six C-shaped fixing springs 26 so as to improve heat radiation from the driver IC to the end bracket. Each coil 29
The terminal 30 is axially fitted in a plurality of small holes around the center hole of the stator 7 into which the vibration-proof rubber cylinder 6 is fitted, and the front end of the terminal 30 is wound around the tip of the coil 29 and soldered. The rear end thereof is electrically connected to the printed circuit board 21 through the elliptical hole 19b of the end bracket 3 via the receptacle 27 covered with the insulating tube 28. Further, the Hall element 22 protruding from the printed board 21 penetrates through the rectangular hole 19c of the end bracket 3 and faces the inner periphery of the rear end of the pole piece 40 made of a permanent magnet of the rotor 8.

Although not shown in detail, the pole piece 40 made of a permanent magnet is held by a presser spring piece 8c (see FIG. 1).
And are arranged in a crescent shape when viewed from the fan 43 side in the central axis direction, and the thickness t in the radial direction at that time is represented by t = Tsin using the angle θ in the circumferential direction as a variable.
It has a sine wave shape represented by 2θ (θ = 1 to 90 °). The reason why the thickness of the pole piece 40 is made sinusoidal in this manner is to significantly reduce cogging generated at the switching position between the pole pieces.

FIG. 6 shows the center hole 3a of the end bracket 3.
Shows the central shaft 4 that is press-fitted. This central axis 4 is
A pair of annular grooves 4a into which E-shaped retaining rings 35a and 35b (see FIG. 1) for restricting axial movement of a pair of grooved ball bearings 31 and 32 (see FIG. 1) to be fitted are fitted. , 4b and the rear end flange 3
Seven. As shown in FIG. 6 (A), a torx-shaped seat 37a having a petal shape in the radial direction and a holding groove 3 are provided inside the flange 37.
7b and a sizing ring 37c are sequentially formed. The shape of the flange portion 37 is used in a struck method known as a press-fitting fixing method, and the center shaft 4 is, for example, a center hole 3a of the end bracket 3 mounted on a receiving die.
Is pressed by a punch 39 from above. Then, the end bracket material on the peripheral edge of the center hole 3a passes over the sizing ring 37c, and the torx-shaped seat 37a and the holding groove 37b
The center shaft 4 is firmly pressed into and fixed to the end bracket 3 easily and precisely at a right angle. The center shaft 4 is made of steel and has grooved ball bearings 31, 32.
Chrome plating is applied to the part where the loose fit
The inner rings of the two bearings can rotate smoothly.

As shown in FIG. 1, a bearing housing 9 rotatably supporting the rotor 8 on the center shaft 4 includes an outer shell comprising a cylindrical portion 9a and a flange portion 9b connected to the rear portion thereof, and a front end plate of the rotor. The first grooved ball bearing 31 in which the outer ring is tightly fitted in the bearing holding ring 8b at the center of 8a, the second grooved ball bearing 32 in which both the inner and outer rings are fitted together, and only the inner ring between the two bearings The spacer 33, which is loosely fitted in contact with the
The grooved ball bearing 32 includes a wave washer 34 that urges the outer ring of the grooved ball bearing 32 rearward in the axial direction. Then, the balls of the two bearings are sandwiched in the axial direction by the urging by the wave washer 34, so that the so-called jump during rolling is eliminated, and vibration and noise are reduced. The reason why the first grooved ball bearing 31 is in contact with the rear E-shaped retaining ring 35b is that the axial center of the permanent magnet magnetic pole piece 40 of the rotor 8 is the magnetic pole of the stator 7. This is because the rotor 8 and the bearing housing 9 are acted on by an electromagnetic force pulling rearward in an attempt to align the centers with each other because they are displaced forward from that of the portion. On the other hand, on the central shaft 4 behind the E-shaped retaining ring 35b, a resin-made stator vibration-proof rubber presser is provided so as to hold the vibration-proof rubber cylinder 6 and the vibration-proof rubber disk 41 between the fixed seat 5 and the center. 36 are fitted closely.

As shown in FIG. 1, an anti-vibration rubber joint 10 is fitted around the outer periphery of the cylindrical portion 9a of the bearing housing 9, and a pressing plate 42 for reinforcing rubber is overlaid on the flange of the anti-vibration rubber joint. These are fixed to the front end plate 8a of the rotor by rivets 11. Then, semicircular protrusions (not shown) are provided at four places on the outer periphery of the cylindrical portion of the vibration-proof rubber joint 10, and the protrusions are formed in the center holes 44 a of the rear end plate 44 of the driven fan 43.
Is inserted into a semicircular concave portion (not shown) on the inner periphery of the bearing to transmit torque from the bearing housing 9 side to the fan 43 side. In addition, the gap dimension generated by fitting these members is set to an optimum value to secure concentricity between the electric motor and the fan 43, and reduce vibration and noise transmitted from the rotor 8 to the fan 43.

On the other hand, as shown in FIG. 1, a fixed seat 5 for attaching the stator 7 to the center shaft 4 is a large-diameter flange portion which abuts against the rear end face of the vibration-proof rubber cylinder 6 to prevent backward movement. 5a and a cylindrical portion 5b whose outer periphery forms two steps of a medium diameter and a small diameter. The cylindrical part 5b is tightly fitted to the center shaft 4, and has three steps on the outer periphery of the cylindrical part 5b with a radial height of two steps. A column key portion 45 is provided.
The anti-vibration rubber cylinder 6 has a small-diameter hole 6a in the first half in the axial direction loosely fitted to the center shaft 4 and a large-diameter hole 6 connected to the rear.
b is fitted by fitting the two-step key groove 46 to the two-step key portion 45 in the axial direction with a small gap in the circumferential direction, and externally fitting the fixed seat 5. further,
The vibration-proof rubber cylinder 6 has the flange 6c abutted on the rear end face of the stator 7, and keys provided at three locations on the outer periphery are fitted into key holes in the center hole of the stator 7 to be internally fitted to the stator 7. The outer periphery of the flange 6c is cut out in a semicircular shape so that the coil terminal 30 can pass therethrough. The reason why the anti-vibration rubber cylinder 6 is interposed between the stator 7 and the center shaft 4 is that the magnetic flux generated in the coil 29 does not have a sine wave shape due to the simplification of the structure of the magnetic pole portion of the stator 7. Cogging that occurs in the stator 7
This is to prevent transmission to the central shaft 4 via the bearings 31 and 32.

The reason why the fixed seat 5 and the vibration-proof rubber cylinder 6 are fitted with the two-stage key described above is that the diameter of the fixed seat 5 is reduced by using a single-stage key.
As a result of an experiment in which the radial thickness of the vibration-proof rubber cylinder 6 was increased by that amount, it was found that noise mainly including high-frequency components was reduced by about 0.2 dB, while vibration mainly including low-frequency components was increased by about 13 μm. Therefore, this is optimal for suppressing both noise and vibration in a well-balanced manner. In addition, as a result of various experiments conducted to minimize the noise caused by cogging, the small gap in the circumferential direction was found to be 0.5 to 0.7 mm. As shown in FIG. 1, the front end face of the vibration-proof rubber cylinder 6 is located 0.5 to 1.0 mm behind the front end face of the iron core of the stator 7.
Note that the cylindrical portion 5b of the fixed seat 5 and the large-diameter hole portion 6b of the vibration-proof rubber cylinder 6 are not necessarily required to have two stages as in this embodiment, but may have only one stage.

An anti-vibration rubber disk 41 (see FIG. 1) fitted to the center shaft 4 with a gap from the front end surface of the anti-vibration rubber cylinder 6
Has six semicircular notches 41a around which the coil terminals 30 are inserted with a gap therebetween, and the edges of each notch are formed as protruding edges 41b protruding forward in the axial direction. The outer peripheral portion of the disk 41 contacts the front end face of the stator 7.
Further, the stator anti-vibration rubber presser 36 fitted between the anti-vibration rubber disc 41 and the E-shaped retaining ring 35b has substantially the same diameter as the E-shaped retaining ring 35b, and the front and rear surfaces thereof are provided on the anti-vibration rubber disc 41. And a thick portion 36a that is in close contact with the retaining ring 35b, and a thin portion 36b having six semicircular notches 36c on the outer periphery that fit into the protruding edge 41b of the vibration-isolating rubber disk 41 with a gap therebetween. Thus,
The outer circumference of the vibration-isolating rubber disk 41 reinforced by the protruding edge 41b is
The semi-circular cutouts 41a and 36c of the stator anti-vibration rubber presser 36 of the anti-vibration rubber disk 41 are in close contact with the peripheral edge of the center hole of the stator 7 to restrict the axial movement thereof.
0, with a gap provided therebetween, to allow the circumferential movement of the stator 7 and the terminal 30 to be free without restraint. And
The axial regulating force is applied to the thick portion 36a of the stator anti-vibration rubber presser 36 which is in close contact with the center of the anti-vibration rubber disk 41.
And received by the E-shaped retaining ring 35b.

The cogging reduction function and the like in the DC brushless motor having the above configuration will be described below. As shown in FIG. 1, an end bracket 3 having a central shaft 4 protruded in a struck manner is housed in a housing 1 via a vibration-proof rubber shell 2 sandwiched in an appropriate compressed state. Here, the anti-vibration rubber shell 2 is mounted such that the annular groove 2b on the outer periphery of the front end is fitted into the annular projections 14, 15 of the housing 1, and the rear end 2c is in contact with the rear end walls 12d, 16 of the housing 1. Therefore, the housing 1 is easily attached and detached, and is securely fixed in the axial direction of the housing 1. Also, the four circular projections 2a on the inner peripheral surface of the vibration-proof rubber shell 2 are appropriately and loosely fitted into through holes 20a provided in the vertical and horizontal directions of the cylindrical portion 20 of the end bracket 3 near the rear end from the center in the axial direction. I agree. Therefore, the center shaft 4 can be attached to the housing 1 at a high perpendicularity and with a single touch, and the driving of the fan 43 having a long shaft length can be performed while saving the assembling labor as compared with a two-piece anti-vibration rubber shell. Even at this time, it is possible to reduce vibration and noise caused by cogging generated in the stator 7 and transmitted from the end bracket 3 to the housing 1 via the center shaft 4. Also, the end bracket 3 to the vibration-proof rubber shell 2
In addition, since the through-hole 20a is located near the rear end, the rigidity is improved, and the vibration and noise generated by the end bracket 3 itself are reduced. Therefore, vibration and noise transmitted from the end bracket 3 to the housing 1 are effectively reduced.

Also, as shown in FIG.
A fixed seat 5 having a two-stage key portion 45 having a two-stage radial height on the outer periphery is fitted and press-fitted, and the two-stage key portion 45 is provided axially in a rear large-diameter hole portion 6b. The step key groove 46 is fitted, the center shaft 4 is fitted with the small diameter hole 6a at the front, and the vibration-proof rubber cylinder 6 is fitted to the fixed seat 5 loosely and non-rotatably. The stator 7 is externally fitted to the cylinder 6 via a key for preventing rotation. The two-stage key fitting with an appropriate gap absorbs cogging generated in the stator 7 as described above, and the fixed seat 5 is fitted only to the rear part of the vibration-proof rubber cylinder 6. Even in the case of a vibration-proof rubber cylinder that is short in the axial direction, transmission of vibration and noise to the center shaft 4 is effectively prevented. Therefore, in combination with the effects described in the previous section, the structure that the assembly and disassembly are easy and the number of man-hours during manufacture can be reduced, and the vibration and noise of the housing 1 caused by cogging generated in the stator 7 can be greatly reduced. can do.

The front end face of the stator 7 mounted with its rear end face in contact with the front end face of the flange 6c of the vibration-proof rubber cylinder 6 has a gap with the front end face of the vibration-proof rubber cylinder 6. In this state, the outer peripheral edge of the anti-vibration rubber disk 41 inserted into the center shaft 4 abuts,
The front end of the coil terminal 30 fitted to the stator 7 is inserted into the six semicircular notches 41a on the outer peripheral edge with a gap. The thick rubber portion 36a of the stator anti-vibration rubber press 36 fitted tightly to the E-shaped retaining ring 35b in front of the center shaft 4 causes the anti-vibration rubber disk 41 to be mainly driven at the central portion. , The movement in the axial direction is restricted, whereby the stator 7 is held so as to be movable in the circumferential direction with respect to the central axis 4 but immovable in the axial direction. Therefore, it is possible to prevent the stator 7 from coming off in the axial direction while restraining the circumferential movement caused by the cogging of the stator 7 and the coil terminal 30 without restraining the cogging, thereby further preventing vibration and sound from cogging. The effect is obtained. As a result, while miniaturizing the motor, cogging generated in the stator 7 at the time of driving is effectively absorbed by the vibration-proof rubber cylinder 6 or the like, so that vibration and noise are prevented from being transmitted to the center shaft 4. Can be.

In addition, in this motor, the vibration-proof rubber disk 4
The outer peripheral notch 41a has a semicircular edge that is a projecting edge 41b that protrudes in the axial direction, so that the notch 41a allows the coil terminal 30 to freely move in the circumferential direction.
Even if is increased, the stator 7 can be securely held in the axial direction by the reinforcement by the protruding edge 41b. Also, the outer peripheral thin portion 36 of the stator anti-vibration rubber press 36 in front of the anti-vibration rubber disc 41.
Since the semicircular notch 36c of b is fitted with a gap in the protruding edge 41b, there is an advantage that the positioning of the rubber vibration insulator presser 36 during assembly is facilitated. Furthermore,
The rotor 8 is so-called cantilever supported via a bearing housing 9 having a pair of grooved ball bearings 31 and 32 on the distal end side of an immovable center shaft 4 protruding from the end bracket 3. Since the driven fan 43 is connected at the location, the axial dimension of the housing 1 can be reduced and the size of the motor can be reduced as compared with the conventional example of the double-sided bearing of FIG.

In the above embodiment, since the rotational force is transmitted to the fan 43 via the vibration-proof rubber joint 10 which is fitted to the bearing housing 9 and fixed to the rotor 8 with the rivet 11, the rotation of the rotor 8 Cogging generated at the joint of the pole pieces 40 can be prevented from being transmitted to the fan 43, and vibration and noise of the entire system can be reduced. Further, only the outer ring of the first grooved ball bearing 31 is tightly fitted to the bearing holding ring 8b,
The inner ring, the inner and outer rings of the second grooved ball bearing 34 and the spacer 33
Are loosely fitted to the center shaft 4 and the bearing housing 9, and these are urged rearward by the wave washer 34, and the axial centers of the stator 7 and the rotor 8 are shifted to each other so that the bearing holding ring of the rotor 8 is electromagnetically moved. 8b is in contact with the rear E-shaped retaining ring 35b via the first grooved bearing 31, so that the inner and outer rings and balls do not slide or jump due to the rotation of the rotor 8, and vibration and noise are reduced. In addition to the further reduction, uneven wear of the rolling surface can be eliminated, the service life of the bearing can be extended, the centering can be simplified, and the assembly and disassembly of the bearing can be facilitated. Further, in the above embodiment, since the center shaft 4 is press-fitted into the end bracket 3 by the struxing method, the center shaft 4 is easily and firmly and at a high right angle to the center shaft 4 compared with fixing by the screwing method or the like. Can be protruded.
In the above embodiment, a total of four circular projections 2a on the inner circumference of the vibration-isolating rubber shell 2 and through holes 20a of the end bracket 3 are provided vertically and horizontally, respectively. Is also good.

[0028]

As is apparent from the above description, in the DC brushless motor of the present invention, the stator is mounted on the center shaft protruding from the mounting member fixed to the housing having the front end opened through the rubber cushion. On the other hand, a permanent magnet rotor externally fitted with a gap therebetween is rotatably mounted on the center shaft via a support member, and the mounting member is a bottomed cylinder having an open front end. A through hole is provided in at least three places in the circumferential direction of the cylindrical portion near the rear end from the center in the axial direction, and the through hole is fitted between the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the housing. A vibration-proof rubber shell with protruding projections is interposed, so that the center axis can be easily and highly perpendicularly mounted to the housing while saving the labor of assembly, and the motor is downsized by the vibration-proof rubber shell and the vibration-proof rubber cylinder. Occurs in the stator while trying to To effectively absorb the cogging, it is possible to reduce the vibration and noise transmitted to the central axis. In addition, the rear end of the vibration-proof rubber shell is brought into contact with the rear end wall of the housing, an annular groove is provided on the outer periphery of the front end, and this is fitted into an annular projection provided on the inner periphery of the front end of the housing. It is easy to assemble and disassemble the vibration-proof rubber shell, and the vibration-proof rubber shell can be securely fixed in the axial direction, so that vibration and noise of the housing can be further reduced. Further, the support member is constituted by a cylindrical portion accommodating a ball bearing fitted to the center shaft, and a flange connected to the rear and fixed to the front end of the rotor. Providing an anti-vibration rubber joint for connection with the center of the end of the driving body allows the rotor to rotate smoothly and ensures concentricity between the motor and the driven body, further reducing vibration and noise. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a DC brushless motor of the present invention.

FIG. 2 is a plan view, a front view, and a sectional view showing a lower housing of the embodiment.

FIG. 3 is a plan view, a front view, and a sectional view showing an upper housing of the embodiment.

FIG. 4 is a plan view, a front view, a cross-sectional view, and a rear view showing the vibration-proof rubber shell of the embodiment.

FIG. 5 is a rear view and a sectional view showing the end bracket of the embodiment.

FIG. 6 is a front view, a sectional view, and a rear view showing a central axis of the embodiment.

FIG. 7 is a sectional view showing a conventional DC brushless motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Anti-vibration rubber shell, 2a ... Circular projection, 3
... End bracket, 4 ... Center axis, 5 ... Fixing seat, 6 ... Vibration-proof rubber cylinder, 7 ... Stator, 8 ... Rotator, 8a ... Front end, 9
... bearing housing, 9a ... cylindrical part, 9b ... flange part, 10 ... vibration-proof rubber joint, 12 ... lower housing, 12d ... rear end wall, 1
Reference numeral 3 denotes an upper housing, 14, 15 an annular protrusion, 16 a rear end wall, 20 a cylindrical portion, 20a a through hole, and 32 a ball bearing with a second groove.

Claims (3)

(57) [Claims] 1. A non-rotatable center shaft (4) is projected from a mounting member (3) fixed to a housing (1) having an open front end, and a vibration-proof rubber cylinder (6) is mounted on the center shaft (4). A rotor (8) having a magnetic pole piece (40) made of a permanent magnet and externally fitted with a predetermined gap to the stator (7) is attached to the rotor (8). A DC brushless motor rotatably mounted on the central shaft (4) via a support member (9), wherein the mounting member (3) is a bottomed cylinder having an open front end; At least three circumferential positions of the cylindrical portion (20) have through holes (20a) closer to the rear end than the center in the axial direction, while the outer peripheral surface of the cylindrical portion (20) of the bottomed cylinder and the housing (1) Between the inner peripheral surface and the through hole (20
A brushless DC motor having a vibration-proof rubber shell (2) having a projection (2a) fitted into (a). 2. The vibration-proof rubber shell (2) has a rear end (2c) abutting on a rear end wall (12d, 16) of the housing (1) and has an annular groove (2b) on the outer periphery of the front end. And this annular groove (2b)
The brushless DC motor according to claim 1, wherein an annular projection (14, 15) provided on an inner periphery of a front end of the housing (1) is fitted to the housing. 3. The support member (9) is connected to a cylindrical portion (9a) accommodating a ball bearing (32) externally fitted to the center shaft (4), and is connected to the rear of the cylindrical portion (9a). Front end of rotor (8)
(8a) and a flange (9b) fixed to the cylindrical portion (9a).
The DC brushless motor according to claim 1 or 2, wherein a vibration-proof rubber joint (10) is provided on an outer periphery of (a) for connecting to a center of an end of the driven body.