JPH09163663A - Induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction motor of long life wherein reverse rotation is prevented by using a fluid bearing, in an induction motor used for a ventilation fan. SOLUTION: In this induction motor, a shaft 2 wherein a snap ring 1 is fixed, and a fluid bearing having a dynamic pressure generating trench 3 on either one of the outer periphery of the shaft 2 or the inner peripheries of two sliding bearings 4 are used. A washer 7 having a protrusion 6 is fixed on an end surface 5 of the bearing of one side. Thereby an induction motor of long life which can prevent reverse rotation of a ventilation fan can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of reverse rotation of a ventilation fan induction motor mounted on a wall or the like.

[0002]

2. Description of the Related Art Conventionally, an electric motor using a fluid bearing is disclosed in JP-A-3-98435. The bearing structure is shown in FIG. 7, and as shown in FIG.
Reference numeral 1 denotes a bearing in which the inner diameter portion 105 is made of a magnetic material in which the groove groove 102 is formed, and the blade side in the drawing is magnetized to the N pole and the opposite blade side to the S pole. An outer diameter portion 103 of the bearing 101 is opposed to a magnetized inner diameter portion 105 by a magnetic body 104, and like the inner diameter portion 105 of the bearing, the blade side of this magnetic body 104 in the drawing is the N pole and the opposite blade side is the opposite side. It is a shaft magnetized to the south pole.

In the above construction, since the shaft 103 does not rotate when the motor is stopped, no dynamic pressure is generated, but the inner diameter portion 105 of the bearing 101 and the outer diameter portion 106 of the shaft 103 are not generated.
Since the opposite parts of are magnetized to have the same polarity,
A magnetic repulsive force is generated between the shaft 103 and the bearing 101.
It is possible to obtain an electric motor having a long-life bearing that is not in contact with each other and is not damaged by abrasion.

[0004]

In such a conventional induction motor structure, the ventilation fan can exhibit a long life when it is operated in the forward rotation direction, but it can rotate backward due to outside wind or the like when the operation is stopped. However, there is a problem that the grease in the bearing disappears in a short period of time when rotating in the reverse direction and the life becomes shorter than that of the conventional slide bearing.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a long-life induction motor capable of preventing reverse rotation of a ventilation fan.

[0006]

In the induction motor of the present invention, the first means is to apply a dynamic pressure to either the shaft to which the retaining ring is fixed, or the outer circumference of the shaft or the inner circumference of the two slide bearings. A fluid bearing having a generating groove is used, and a washer having a protrusion at one end of the bearing is fixed.

According to the present invention, it is possible to obtain the long-life induction motor capable of preventing the reverse rotation of the ventilation fan.

Further, in order to achieve the above object, the second
The means is configured to fix a permanent magnet to the inner bottom of the motor housing on the side opposite to the blade.

Further, in order to achieve the above object, a third
This means has a hole in which the end face of the shaft on the side opposite to the blade is tapered only in one direction, and a notch having a size insertable into this hole is provided in the motor housing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is such that a dynamic pressure generating groove is provided on either the shaft to which the retaining ring is fixed, or the outer circumference of the shaft or the inner circumference of the two slide bearings. This is a configuration of an induction motor in which a fluid bearing is used, and a washer with a protrusion is fixed on one end of the bearing. Since the shaft is in the opposite direction, the force that pushes the shaft against the slide bearing end face opposite to that during operation works, and the retaining ring fixed to the shaft engages with the washer fixed to the slide bearing end face to stop the rotation. It has the effect of being able to.

The invention according to claim 2 is the structure of the induction motor according to claim 1 in which a permanent magnet is fixed to the inner bottom part of the motor housing on the side opposite to the blades, and the blades of the ventilation fan rotate in the reverse direction, and the shaft Since the retaining ring fixed to and the washer fixed to the end surface of the sliding bearing are engaged, and after the rotation is stopped, the end surface of the shaft is attracted and fixed to the permanent magnet.
It does not easily rotate until the operation is started, and has an effect of preventing reverse rotation.

According to a third aspect of the present invention, the end surface of the shaft on the side opposite the blade has a hole tapered in only one direction, and a notch having a size that can be inserted into this hole is provided in the motor housing. According to the constitution of the induction motor of item 1, when the blade of the ventilation fan rotates in the reverse direction, the thrust of the blade pushes the shaft to the side opposite to the blade, and the notch provided in the motor housing is in one direction of the shaft end surface. It has the function of being inserted into the tapered hole and preventing reverse rotation. In addition, since the hole is tapered, the notch can be easily removed from the hole during normal rotation.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) As shown in FIGS. 1 and 2, reference numeral 1 denotes a retaining ring, which is a commercially available E-type retaining ring or K-type retaining ring. The shaft 2 to which the retaining ring 1 is fixed is the shaft 2
It is held by two slide bearings 4 each having a dynamic pressure generating groove 3 on the outer periphery of one of them, and a projection 6 is formed on the inner end surface portion 5 of one slide bearing 4.
The washer 7 provided with is press-fitted and fixed. A stator 8 is fixed to the motor housing 9 together with the slide bearing 4. Reference numeral 10 is a blade of a ventilation fan fixed to the shaft 2.

In the induction motor of the ventilation fan thus constructed, during normal operation, the rotation of the blade 10 causes wind to flow toward the induction motor, the thrust of the blade 10 acts on the blade 10 side, and the shaft 2 moves toward the blade 10 side. The plain bearing 4 is pressed and rotates. However, if the blade 10 rotates in the reverse direction due to outside wind when the operation is stopped, the thrust of the blade 10 will be in the opposite direction to that in the normal rotation, so that the shaft 2 will be pressed against the slide bearing 4 on the side opposite the blade 10 to rotate. However, a washer 7 having a projection 6 is fixed to the end surface of the plain bearing 4, and the rotation can be stopped by engaging with a retaining ring 1 fixed to the shaft 2.

In the drawing, the direction of the wind at the time of forward rotation is the induction motor side, but the opposite rotation direction is forward rotation and the washer 7 provided with the projection 6 is fixed to the slide bearing 4 on the blade 10 side. The same effect can be obtained without any change in action.

Further, in the figure, a washer 7 having a projection 6 is provided.
Is press-fitted and fixed to the end surface portion 5 of the slide bearing 4,
Even if it is fixed by a different method such as adhesion, the action is the same and the same effect can be obtained.

(Second Embodiment) A description will be given with reference to FIG.
The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG.
A washer 7 provided with a protrusion 6 is press-fitted and fixed to the inner end surface portion 5 of the side slide bearing 4. In addition, anti-blade 1
A permanent magnet 11 is provided on the inner bottom of the motor housing 9 on the 0 side.
Has been fixed.

In the induction motor of the ventilation fan constructed as described above, the action of stopping the reverse rotation of the blades 10 is the same as that of the first embodiment, but at the same time it stops, the end portion 1 of the shaft 2 is stopped.
Since 2a is attracted and fixed to the permanent magnet 11, it does not easily rotate until the operation is started, and it is possible to prevent reverse rotation.

(Third Embodiment) A third embodiment will be described with reference to FIGS. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 4, a washer 7 provided with a protrusion 6 is press-fitted and fixed to the inner end surface portion 5 of the slide bearing 4 on the side opposite the blade 10. Also,
The end surface 12b of the shaft 2 on the side opposite to the blade 10 has a hole 14 having a taper 13 only in the forward rotation direction.
A notch 15 sized to be inserted into the motor housing 9
It is provided in.

In the induction motor of the ventilation fan constructed as described above, when the blade 10 starts to rotate in the reverse direction, the thrust of the blade 10 pushes the shaft 2 toward the side opposite to the blade 10 and the notch provided in the motor housing 9. 15 is a taper 13
At the same time as being inserted into the hole 14 so as to be guided to, the retaining ring 1 and the projection 6 provided on the washer 7 are engaged with each other to prevent reverse rotation as in the first embodiment. When the blade 10 rotates forward, the taper attached to the hole 14
The notch 15 does not easily come off the hole 14 and prevent rotation.

In the embodiment, the motor housing 9
Although the notch 15 is provided by cutting a part of the above, the same effect can be obtained even if another member is fixed by welding or the like.

[0022]

As described above, according to the present invention, there is an advantageous effect that a long-life induction motor for a ventilation fan that uses a fluid bearing and can prevent reverse rotation can be provided at a low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an induction motor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a slide bearing and a washer of an induction motor according to the same embodiment.

FIG. 3 is a sectional view showing an induction motor according to another embodiment of the present invention.

FIG. 4 is a sectional view showing an induction motor according to another embodiment.

FIG. 5 is a side view showing a shaft end portion of an induction motor according to another embodiment.

FIG. 6 is a front view showing a shaft end portion of an induction motor according to another embodiment.

FIG. 7 is a sectional view showing a fluid bearing portion of a conventional induction motor.

[Explanation of symbols]

 1 snap ring 2 shaft 3 dynamic pressure generating groove 4 fluid bearing 5 fluid bearing end surface portion 6 protrusion 7 washer 11 permanent magnet 12a shaft end portion 12b shaft end surface 13 taper 14 hole 15 notch

Claims (3)

[Claims] 1. A shaft having a retaining ring fixed thereto and a hydrodynamic bearing having a dynamic pressure generating groove on either the outer periphery of the shaft or the inner periphery of two slide bearings are used, and one end face of the bearing has a protrusion. An induction motor with a fixed washer. 2. The induction motor according to claim 1, wherein a permanent magnet is fixed to the inner bottom of the motor housing on the side opposite the blade. 3. The induction motor according to claim 1, wherein the shaft end surface on the side opposite to the blade has a hole tapered in only one direction, and a notch having a size insertable into this hole is provided in the motor housing.