JPH0312045Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a direct brushless fan motor used as an air blowing means.

[Conventional technology]

BACKGROUND ART DC brushless fan motors are often used as air blowing means for cooling equipment that generates heat or for use in blowers and the like. A DC brushless fan motor includes a frame, a stator supported by the frame, a rotating shaft rotatably supported by a pair of bearings installed in a bearing cylinder fixed to the frame, and a rotating shaft supported by the rotating shaft. It consists of a magnetic rotor with blower blades attached to the shaft.

FIG. 2 shows the structure of a conventional fan motor of this kind, in which 1 is a frame having a wind tunnel 102 and a ventilation window 105, and 2 is a frame 1
a stator attached to a bearing cylinder 6' fixed to the
3 is a rotating shaft rotatably supported by a pair of ball bearings 7A' and 7B' attached to the inner periphery of a bearing cylinder 6'; 4 is a rotating shaft having a permanent magnet 402 and a blower blade 404; 3 is a magnet rotor attached to the rotor.
A coil spring S is disposed between one of the bearings 7A' and a protrusion 6a' provided on the inner circumference of the bearing cylinder 6', and the coil springs S cause the bearings 7A' and 7B' to move around the rotation axis. 3 and the rotor boss 400. A printed circuit board 12 is also attached to the frame 1, and a predetermined current is supplied to the winding 202 of the stator 2 by a drive circuit made up of electronic components mounted on this mounting substrate, thereby driving the rotor 4. .

FIG. 3 shows another conventional example in which the support structure of the rotating shaft is different. In this example, oil-impregnated sliding bearings 8A' and 8
B' is fitted, and the rotating shaft 3 is supported by these bearings. The bearings 8A' and 8B' are held down by shield washers 9A' and 9B' fitted on the inner periphery of the bearing cylinder 6', respectively, and the thrust washer 11 fitted on the rotating shaft 3 is pressed against the boss of the magnet rotor 4. It is in contact with the end face of 400. Further, a retaining ring 10' is attached to the end of the rotating shaft 3.
A plurality of thrust washers 13 are located between the retaining ring 10' and the shield washer 9A'.
is fitted. Other points are similar to the brushless fan motor shown in FIG.

In each of the DC brushless fan motors described above, when a drive current is applied to the stator winding 202 by the drive circuit configured on the printed circuit board 12, the magnet rotor 4 rotates, so the blower blades 404 rotate in the wind tunnel 101. Then, air is sent through the ventilation window 105 in the direction of arrow A shown in the figure.

[Problem that the invention attempts to solve]

In the conventional DC brushless fan motor shown in FIG. 2, a pair of bearings 7A',
Since both 7B' were made of expensive ball bearings,
There was a problem of high costs. In addition, ball bearings have the problem of being weak against axial shock and vibration, and also generate relatively large noise.

Further, as shown in Fig. 3, when the rotating shaft is supported by a sliding bearing, the thrust washer 13
Various problems arise due to the sliding contact between the shield washer 9A' and the shield washer 9A'. That is, in this type of motor, the magnetic attraction force generated by the deviation between the magnetic center of the permanent magnet 402 of the magnet rotor 4 and the magnetic center of the stator 2 causes the rotating shaft 3 to move in the direction opposite to the air blowing direction (as shown by the arrow in the figure). B direction) is applied, and the wind pressure acting on the blower blades 404 also applies a force in the direction of arrow B to the rotary shaft 3, so that the thrust washer 13 is kept pressed against the shield washer 9A' while the motor is rotating. Ru. Therefore, heat is generated at the sliding contact surface between the thrust washer 13 and the shield washer 9A', and this heat generation has caused a problem that the life of the oil-impregnated bearing is shortened. Furthermore, since sliding noise is generated by the sliding contact between the thrust washer 13 and the shield washer 9A', there is a problem in that the original characteristic of the sliding bearing, which is low noise, cannot be utilized.

[Means for solving problems]

As shown in FIG. 1 showing an embodiment of the present invention, the present invention includes a frame 1, a stator 2 supported by the frame, a rotating shaft 3 rotatably supported by the frame, and a stator 2 supported by the frame. It consists of a magnet rotor 4 with blower blades attached to a rotating shaft, and the magnet rotor is arranged so that the magnetic center of the magnet rotor is shifted from the magnetic center of the stator to the front side in the air blowing direction by the blower blades. This is a DC brushless fan motor that is designed to reduce costs, extend life, and reduce noise.

Therefore, in the present invention, among the pair of bearings 7 and 8 that support the rotating shaft 3, one bearing 7 is located on the front side (direction of arrow A) in the direction of air blowing by the blower blades 404, and the other bearing 7 is located on the side of the front side (in the direction of arrow A) in the direction of air blowing by the blower blades 404; The other bearing 8 located on the (B direction) side consists of a ball bearing and a sliding bearing, respectively. A retaining ring 10 is attached to one end of the rotating shaft 3 on the side of the bearing 7, and this retaining ring 10 directly or indirectly (via a washer or the like) contacts the inner ring 7b of the ball bearing 7 to stop the rotation. Position the axis. Then, the retaining ring 10 is moved around the inner ring of the ball bearing 7 due to the magnetic attraction force generated between the magnet rotor 4 and the stator 2 in a direction that urges the rotating shaft 3 backward in the air blowing direction and the wind pressure acting on the air blower blades. It is adapted to be held in a state in which it is in direct or indirect contact with 7b.

[Effect of invention]

As mentioned above, if a ball bearing is used as the bearing located on the front side of the air blowing direction and a sliding bearing is used as the bearing located on the rear side of the air blowing direction, the relationship between the bearing located on the front side of the air blowing direction and the retaining ring is Since no sliding occurs between the two, heat generation and sliding noise can be prevented. In addition, by combining a ball bearing and a sliding bearing as described above, the sliding bearing can compensate for the disadvantages of ball bearings, which are relatively loud and weak against shock and vibration in the axial direction. Coupled with the fact that no heat generation or sliding noise occurs on the bearing side, a motor with low noise and long life can be obtained. Furthermore, when a ball bearing and a sliding bearing are used in combination as described above, costs can be reduced compared to when two ball bearings are used.

In addition, as mentioned above, the wind pressure caused by air blowing,
When the rotating shaft is biased by the magnetic attraction force generated between the magnet rotor and the stator and the retaining ring is held in direct or indirect contact with the inner ring of the bearing, the axial direction of the rotating shaft is It is possible to prevent vibration and ensure stable rotation.

As described above, according to the present invention, a low-noise, long-life DC brushless fan motor can be obtained by taking advantage of the respective advantages of ball bearings and sleeve bearings.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which a peripheral wall 101 of a frame 1 has an appropriate contour shape such as rectangular or circular, and a wind tunnel 102 is formed inside the peripheral wall 101. ing. Peripheral wall part 101
A cup-shaped end wall 103 is disposed at the center of one end in the axial direction, and the outer periphery of the end wall 103 is connected to the peripheral wall 101 by a number of radially provided rectifying plates 104. These many rectifying plates 10
A ventilation window 105 is formed between each of the holes 4 and 4.

A boss portion 106 is provided at the center of the end wall 103, and the bearing cylinder 6, which also serves as a stator support member, is fitted onto the inner periphery of the boss portion 106. A protrusion 601 is provided approximately at the center of the inner circumference of the bearing cylinder 6, and a pair of bearings 7 and 8 are fitted on both sides of the protrusion 601, and both bearings are brought into contact with the protrusion 601 for positioning. has been done.

Among these bearings, one bearing 7 located on the front side in the direction of air blowing by the blower blades (direction of arrow A in the figure) is a ball bearing, and the other bearing 7 is located on the rear side in the direction of air blowing (direction of arrow B in the figure). The bearing 8 is a sleeve-shaped oil-impregnated sliding bearing. A ring-shaped shield washer 9 is fitted onto the inner periphery of the end of the bearing cylinder 6 on the bearing 8 side, and this shield washer prevents the bearing 8 from coming off and prevents lubricating oil from flowing out.

In this embodiment, the inner diameter of the bearing cylinder 6 is set so that the outer ring 7a of the ball bearing 7 and the oil-impregnated bearing 8 can be fitted onto the inner periphery of the bearing cylinder 6 with a clearance fit. Makes installation easy.

A rotating shaft 3 is supported by the bearings 7 and 8, and a retaining ring 10 is fitted into a groove provided at the end of the rotating shaft 3 on the bearing 7 side. This retaining ring 10 comes into contact with the inner ring 7b of the ball bearing 7 to position the rotating shaft 3 in the axial direction.

The stator 2 has a winding 202 wound around a slot of an annular armature core 201, and the core 201 is fitted onto the outer periphery of a bearing cylinder 6.

The magnet rotor 4 has a boss 400 at one end of the rotating shaft 3.
A substantially cup-shaped yoke 401 fixed through the
and a permanent magnet 402 fixed to the inner circumference of the yoke.
A cup-shaped blower blade support member 403 is arranged to surround the yoke 402 from the outside and is also fixed to the rotating shaft 3 via the boss 400, and a cup-shaped blower blade support member 403 is provided radially around the outer circumference of the blower blade support member 403. The air blower support member 403 and the air blower blades 404 are integrally molded from synthetic resin or the like.

The magnetic pole of the permanent magnet 402 is the iron core 201 of the stator 2
In this embodiment, the magnetic center of this magnet 402 is located in front of the magnetic center of the stator core 201 in the air blowing direction (in the direction of arrow A). The magnet rotor 4 and the stator 2 are arranged so as to be shifted to the side, so that a magnetic attraction force acts between the magnet rotor 4 and the stator 2 in a direction that urges the rotating shaft 3 toward the rear in the air blowing direction (in the direction of arrow B). ing.

A thrust washer 11 is fitted to a portion of the rotating shaft 3 located between the bearing 8 and the boss 400, and the end surface of the boss 400 is in contact with the washer 11.

A printed circuit board 12 is fixed inside the end wall 103 of the frame. Although not particularly shown,
This printed circuit board 12 includes a position detection element that detects the position of the magnetic pole of the magnet rotor 4, and a drive circuit that controls the current flowing through the winding 202 of the stator 2 according to the position of the magnetic pole of the magnet rotor. electronic components are installed.

In the DC brushless fan motor described above, the rotation of the magnet rotor 4 causes the blower blades 404 to rotate, and air is sent through the blower window 105 in the direction of arrow A shown in the figure. At this time, the wind pressure acting on the blower blades 404 urges the rotary shaft 3 toward the rear in the blowing direction (in the direction of arrow B in the figure). Further, the rotating shaft 3 is urged toward the rear side in the air blowing direction by the magnetic attraction force acting between the magnet 402 and the stator core 201. This magnetic attraction force is the same as the attraction force generated between magnets of different polarities, and is generated so as to eliminate the difference between the magnetic center of the magnet rotor 4 and the magnetic center of the stator. This magnetic attractive force is an attractive force generated between the magnet 402 of the magnet rotor 4 and the stator core 201 when the stator is not excited. These urging forces keep the retaining ring 10 in contact with the inner ring 7b of the bearing 7 while the motor is rotating. The inner ring 7b of the bearing 7 rotates together with the rotary shaft 3, but when a force is applied to the rotary shaft 3 in the rear direction of the air blowing direction (in the direction of arrow B in the figure), the rotary shaft 3 tends to move in the direction in which the force is applied. . However, in this embodiment, since the retaining ring 10 is held in contact with the inner ring 7b of the bearing 7, vibration in the axial direction of the rotary shaft 3 due to wind pressure or magnetic attraction force is prevented. Further, the retaining ring 10 directly and strongly contacts the inner ring 7b of the bearing 7 and rotates together with the rotating shaft 3 due to the wind pressure and magnetic attraction force, so that the retaining ring 10 and the inner ring 7b of the bearing 7 slide together. No contact occurs, and no sliding noise or heat generation occurs due to sliding. Therefore, heat is not transferred from the bearing 7 side to the oil-impregnated bearing 8 through the rotating shaft 3 and the bearing cylinder 6, and the oil-impregnated bearing 8
The lifespan of the product will not be shortened.

In the above embodiment, the retaining ring 10 is brought into direct contact with the inner ring 7b of the bearing 7, but a washer is interposed between the retaining ring 10 and the inner ring 7b of the bearing 7, so that the retaining ring 10 is brought into contact with the inner ring 7b of the bearing 7. It may be made to contact 7b indirectly.

[Effects of the invention] As described above, according to the present invention, by using a ball bearing as the bearing located on the front side of the air blowing direction and using a sliding bearing as the bearing located on the rear side of the air blowing direction, the air blowing direction can be adjusted. In addition to preventing sliding between the bearing located on the front side of the bearing and the retaining ring, the number of noisy ball bearings has been halved, preventing heat generation and sliding noise from occurring from the bearing. This makes it possible to reduce the noise generated by the motor and extend the life of the bearing, thereby making it possible to obtain a motor with low noise and long life. Furthermore, since a ball bearing and a sliding bearing are used in combination, there is an advantage that costs can be reduced compared to the case where two ball bearings are used.

Furthermore, in this invention, the rotating shaft is biased by the wind pressure generated by the air blowing and the magnetic attraction force generated between the magnet rotor and the stator, and the retaining ring is directly or indirectly brought into contact with the inner ring of the bearing. Since the rotating shaft is held in this state, axial vibration of the rotating shaft can be prevented and stable rotation can be performed.

[Brief explanation of the drawing]

FIG. 1 is a half longitudinal sectional view showing an embodiment of the present invention;
FIGS. 2 and 3 are half longitudinal sectional views showing different conventional examples. 1... Frame, 2... Stator, 3... Rotating shaft, 4... Magnet rotor, 401... Yoke, 40
2...Permanent magnet, 404...Blower blade, 6...Bearing cylinder, 7...Ball bearing, 8...Sleeve-shaped oil-impregnated sliding bearing, 10...Retaining ring.

Claims (1)

[Claims for Utility Model Registration] A frame, a stator supported by the frame, and a rotating shaft rotatably supported relative to the frame by a pair of bearings spaced apart in the axial direction. , a magnet rotor with blowing blades attached to the rotating shaft, and the magnet rotor is arranged so that the magnetic center of the magnet rotor is shifted from the magnetic center of the stator to the front side in the direction of air blowing by the blowing blades. In a DC brushless fan motor in which a rotor is disposed, one of the pair of bearings located on the front side in the air blowing direction and the other bearing located on the rear side in the air blowing direction are a ball bearing and a sliding bearing, respectively. A direct current comprising a bearing, and a retaining ring for positioning the rotating shaft by directly or indirectly contacting the inner ring of the ball bearing is attached to the end of the rotating shaft on the one bearing side. Brushless fan motor.