JPH0652995B2 - Small electric fan device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used as, for example, a small brushless electric fan for circulating indoor air to a temperature sensor of a car air conditioner and a cooling fan for a circuit of a personal computer or a computer. . It is especially effective as a small fan for local cooling. Further, the cooling fin of the electronic circuit can be integrated with the cooling fin so that the cooling effect can be remarkably increased as compared with the natural convection, and an effective means can be provided.

[Conventional technology]

In order to achieve the same purpose as described above, various types of brushless small electric fans have been proposed.

As a type similar to the device of the present invention, a fan of about 30 mm to 40 mm is provided on the rotary shaft of a known DC commutator motor having a diameter of about 20 mm to 30 mm.

Further, there is a brushless electric motor having the above-mentioned configuration.

[Problems to be Solved by the Present Invention]

Since the above-mentioned fan motor is a commutator motor, it has a mechanically worn portion, its service life is short, and it is difficult to achieve a general demand of 20,000 hours.
There is a problem.

Further, the second problem is that mechanical noise is generated.

When the brushless electric motor is used, the first and second problems are solved, but the third problem that the cost is increased and the size is increased occurs. Further, if the one-phase brushless motor is used, the price is small and the size is small, but there is a fourth problem that efficiency is remarkably deteriorated.

The above-mentioned conventional one-phase semiconductor motor has the following problems. At the desired and final stage when rotating 180 degrees in electrical angle, especially at the final stage, the counter electromotive force is zero, and the magnetic core is magnetically saturated, causing an excessive armature current to flow and torque. This causes a large amount of jule loss that does not contribute to the reduction of efficiency. Even when it is not saturated, a large current is flowing because there is no counter electromotive force, which also causes a decrease in efficiency.

Since the shape is generally elongated, there is a fifth problem that it is difficult to integrate the cooling fin and the fan motor into one component in order to blow air to the cooling fin to enhance the cooling effect. is there.

[Means for solving problems]

Since it is an abduction type one-phase semiconductor motor, the first, second, and
Solves the third problem.

Since the electric current of about 40 degrees is cut off at the end of energization without conducting the electric current of 180 degree at the electric angle, the efficiency is increased to 60% or more. Therefore, the fourth problem is solved.

Since it has a special structure as shown in FIG. 1, a relatively flat electric motor can be obtained. Therefore, it becomes easy to integrate the cooling fins, and the fifth problem is solved.

[Action]

According to the above-mentioned means of the present invention, there is an effect that the problems or drawbacks of the conventional techniques are eliminated.

That is, noise is reduced, efficiency is increased, it can be made flat, lightweight and inexpensive, and a fan with a diameter of 35 mm or less can be used. Also, since it is a semiconductor motor, the service life can be set to 20000 hours or more.

Furthermore, in the initial stage of energization of the armature coil, in the case of an electric motor with a magnetic core or core, its inductance is about 15 millihenries (in the case of an electric motor with an output of about 0.5 Watts),
The rise of the current is relatively slow, the back electromotive force is small, but the current value is small, the jule loss is small, and the effect on the efficiency is small, but the efficiency is slightly lowered.

However, at the end of energization, the core is almost saturated by the magnetic flux of the magnet rotor, and the inductance becomes only the coil, so the inductance decreases to about 3 millihenries. Therefore, at the end of energization when the field magnetic field is small or zero, a remarkably large armature current flows, and this does not contribute to torque, which is the main cause of efficiency deterioration.

In order to eliminate such inconvenience, at least in the final stage of energization, the current is cut off and the efficiency is 20 to 25
It is the action of the present invention that the percentage is increased to about 60%.

The configuration shown in FIG. 1, that is, the outer rotation type and the flat configuration, the blowing can be selected in the axial direction and the outer radial direction. Therefore, it can be used also as an axial flow fan, and when combined with a cooling fin, it can be constructed in a small size.

〔Example〕

Next, details of the device of the present invention will be described with reference to an embodiment shown in the drawings. Note that the same symbols in the drawings are the same members, and therefore their explanations are omitted. The description will be given with reference to FIGS.

FIG. 1 shows a cross-sectional view of the device of the present invention. Symbol 1 is a side plate, which is a disk made of a non-magnetic material, and a second plate.
FIG. 2B is a plan view of the structure shown in FIG. 1 seen from the direction of arrow E.

An oil-impregnated bearing 4a is fitted in a circular hole 1c at the center of the side plate 1, and a rotary shaft 2 is rotatably supported by the oil-impregnated bearing 4a.

Reference numeral 10 is an armature core formed by laminating silicon steel plates, and the details as seen from the direction of arrow E are shown in FIG. 2 (c). That is, four salient poles having a shape shown in the figure (90 ° apart from each other) are provided, and armature coils 7a, 7b, 7c, 7d are attached to the salient poles 10a, 10b, 10c, 10d.

The portions of the salient poles 10a and 10b indicated by the dotted lines 10e and 10f are deleted. As will be described later, this is a means for generating a cogging torque so as to be self-started. The salient poles 10c and 10d have the same structure. The symbol 10g is a hole.

On the circular protrusions 1a and 1b of the side plate 1 (indicated by the same symbols in FIG. 2 (b)), the salient pole side portions of the armature magnetic core 10 are attached and fixed as shown. , Fixed armature.

Reference numeral 3 is an outer casing, which is made by pressing a mild steel plate. The right side of the cup-shaped outer casing 3 is fixed to the side plate 1, the left side is bulged, and the oil impregnated bearing 4b is fitted in the central circular hole thereof to support the rotary shaft 2. On the inside of the right side opening of the rotor 5 made by pressing a mild steel plate into a cup shape, a circle-shaped (ring-shaped) magnet 6 (magnet rotor) is attached, and the inside has a gap. Salient pole through 10
It faces a, 10b, .... Magnet rotor 6
As shown in FIG. 2 (c), four N and S magnetic poles are arranged in the same pitch, and each magnetic pole is magnetized in the radial direction.

Fans 8a, 8b, ... Fixed on the circumference of a disk-shaped base 8 at an opening angle of 90 degrees are provided at the left end of the rotary shaft 2. FIG. 2 (a) shows the rotary shaft 2 and the fans 8, 8a, 8b, ...
FIG.

The ring 3a whose base is fixed to the outer casing 3 includes the fans 8a, 8
so that the outer ends of b, ... Are crowned, and the symbols 9a, 9b,
A plurality of holes shown by ... are provided in the entire circumferential portion, that is, the annular portion.

The apparatus shown in FIG. 1 is a one-phase semiconductor motor, and its rotating means will be described with reference to FIGS.

In FIG. 4, the Hall element 11 is a magnet rotor 6
Is fixed to the fixed armature so as to face the N and S magnetic poles.

Therefore, by facing the N and S magnetic poles, the Hall element
The output of 11 is amplified by the linear amplification circuits 11a and 11b. These outputs when facing the north pole are shown as curves 17, 17a in the time chart of FIG. At these intermediate positions, position detection signals of the same shape are obtained when they face the south pole, but they are not shown in the drawing.

The output of the amplification circuits 11a and 11b charges the capacitor 21, and the charging voltage is shown as curve 18b.

The voltage attenuated by resistors 24a and 24b at a predetermined rate is shown as curve 18c in FIG.

The voltage level due to the voltage drop of the resistor 23 is shown by the dotted line in Fig. 3.
It is shown as 18a. Therefore, the high-level output of the operational amplifier 20a is generated at the position of the dotted line 16a which is the intersection of the dotted line 18a and the curve 17. The angle between the dotted line 16a and the rising point of the curve 17 is about 5 to 10 degrees in electrical angle. Since all angle displays thereafter are displayed in electrical angles, the letters of electrical angles are omitted.

At the intersection of the dotted line 18c and the curve 17, the output of the operational amplifier 20a is converted to low level. That is, the output of the operational amplifier 20a becomes high level only between the dotted lines 16a and 16b.

Therefore, at this time, the transistors 25a and 25b become conductive, and the armature coil G is energized rightward. The armature coil G is a coil in which the armature coils 7a, 7b, 7c, 7d of FIG. 2 are connected in series or in parallel.

The height of the right end of the curve 18b is proportional to the peak value of the curve 17. The curve 18c is also proportional to the peak value. Therefore,
Even if the output of the Hall element 11 changes, the position of the dotted line 16b does not change, so there is an effect that the energization section of the armature coil G does not change while the output of the operational amplifier 20a is at the high level.

The above-mentioned circumstances are exactly the same with respect to the operations of the amplification circuit 11b and the operational amplifier 20b. When the Hall element 11 faces the south pole, only the section corresponding to the dotted lines 16a and 16b has the operational amplifier.
The output of 20b becomes high level, and transistors 25c and 25
d is conducted, and the armature coil G is energized to the left. When the energization of the armature coil G is finished, the diodes 26a, 26a
Since the base voltage of the transistor 22 is converted to the low level via b, the transistor 22 becomes conductive and the capacitor 22
21 can be discharged and ready for the next operation. In FIG. 3, symbol 6 is a development view of the magnet rotor, and arrow F
Rotate in the direction.

When the armature coil G shown in FIG. 4 is energized by reciprocating with a full width of 180 degrees, the output torque becomes as shown by curves 12a, 12b, .... The curves 12a, 12c, ... Are torque curves when energized to the right, and the curves 12b, 12d, ... Are torque curves when energized to the left.

The curve 13 is a cogging torque curve, and as described above, the outer surface of the salient poles 10a, 10b, ...
This is because it is deleted diagonally as indicated by 0e and 10f, and the positive peak value of the cogging torque curve 13 is located at the dead point (point of zero torque) of the torque curves 12a, 12b, .... Has been

Therefore, since the dead point is removed, the magnet rotor 6 can be self-started at any position.

The curve 14 is the cogging torque due to the attractive force between the salient poles 12a, 12b, ... And the magnetic poles of the field magnet (magnet rotor 6), but since the phase is 45 degrees behind curve 13, it is described above. Interfere with self-start operation. Therefore, salient pole 10a,
It is preferable to make the gap between 10b, ...

As described with reference to FIG. 4, when the magnet rotor 6 is on the left side of the dotted line 16a in FIG. Start and rotate, dotted lines 16a and 16
Since electricity is supplied during b, continuous rotation is performed.

When a voltage is applied and the magnet rotor 6 is located on the right side of the dotted line 16b, the capacitor 21 of FIG.
Is not charged yet, the armature coil G is energized and activated. Further, the positive torque of the cogging torque curve 13 has an effect that the starting torque is added to continue the rotation.

It is impossible to accurately position the Hall element 11 at the position of the boundary between the curves 12a and 12b during mass production. For example, if it is deviated to the right, counter torque shown by the dotted line 12 is generated, and when this value is equal to the positive torque of the curve 13 or becomes larger than the positive torque of the curve 13, self-starting becomes impossible. But,
In the present embodiment, since the energization on the left side of the dotted line 16a is cut off by the voltage due to the voltage drop of the resistor 23 in FIG. 4, the armature coil G is not energized, so that the above-mentioned counter torque is generated. Since it does not, there is an effect that self-starting is completely performed.

After self-starting, energization is performed only between the dotted lines 16a and 16b, so the efficiency is remarkably increased. Next, the reason will be described.

When the magnetic pole of the magnet rotor 6 of FIG. 2 (c) and one of the salient poles completely face each other, energization of the armature coil is started,
A general one-phase electric motor is driven and is energized until it faces the next magnetic pole, that is, for 180 degrees.

The energization at this time has a steep rise due to the accumulation of magnetic energy, and becomes a curve like the left side of the curve 15 in FIG. In this part, the output torque is small, but the jule loss is small and the efficiency is not greatly affected.

In the middle of the curve 15, the back electromotive force is large and the armature current is small, but at the end, there is almost no back electromotive force and the magnetic core is close to saturation, so the armature current increases rapidly as shown in the figure. . Furthermore, the magnetic energy proportional to the inductance also decreases sharply, so that the released magnetic energy results in an increase in the armature current. Therefore, as shown in the right end of the curve 15 in FIG. 3, when the armature current sharply increases and rotates 180 degrees, the armature current is cut off. Is almost the same value as.

In this vicinity, since the field magnetic field is small or zero, there is almost no output torque, and the ineffective Jule loss increases rapidly.

The situation is exactly the same for the other magnetic poles.

Assuming an electric motor of 3000 revolutions per minute, 4 curves per revolution
Since 15 is obtained, the energization shown by the curve 15 of 12000 pieces per minute is performed. This fact, in an extreme way,
It should be understood that this is a DC motor that is started up 12,000 times, which is the main cause of efficiency deterioration.

In order to eliminate the above-mentioned defects, the most suitable means is to stop the energization of the armature current at the point indicated by the dotted line 16b in FIG. That is, it is preferable to cut off the current at the dotted line 16b. Since the torque on the left side of the dotted line 16a is small, the influence on the efficiency is small.

As described above, since the energization is cut off in the initial and final stages of energization, even if the position of the Hall element 11 is slightly deviated, there is no mixing of anti-torque, and the advantage of facilitating manufacturing and the effect of increasing efficiency are obtained. is there. According to the actual measurement, the efficiency of the one-phase electric motor energized 180 degrees is about 30%, but the one according to the present embodiment has an effect that the efficiency is about 60%.

When the armature current is cut off at the dotted line 16b, the magnetic energy stored in the armature coil G is discharged by the diode reversely connected to the transistors 25a, 25b, ... Increase the output. When energized at 180 degrees, the stored magnetic energy is discharged as shown by the dotted line 15b, which causes anti-torque, which is a drawback that reduces efficiency.

As described above, the motor rotates as a one-phase electric motor. At this time, the fans 8a, 8b, ...
Rotates to generate an air flow in the directions of arrows C and D. As can be understood from the structure, the device of the present invention can be relatively flat and small in diameter (diameter is about 30 to 40 mm), so that it is effective as the use described above in the field of industrial application. The means can be provided.

Air is blown out in the directions of arrows C and D, but suction is performed through the holes 9a, 9b, ... In FIG.

By reversing the rotation of the fans 8a, 8b, ..., Radial fans can be sucked in from the left and blown out in the directions of arrows A, B from the holes 9a, 9b ,. Next, the curve 17a in FIG. 3 will be described.

The case where the transistor 22 and the diodes 26a and 26b in FIG. 4 are removed and the required amount of the capacitor 21, that is, the time constant is increased will be described. For example, if the time constant is about several seconds, the operational amplifier 20
Since the input of one terminal of a and 20b is small, it energizes approximately 180 degrees and self-starts.

After a few seconds, the level of one terminal rises and reaches the position of the dotted line 18d in FIG. 3, so the armature current energization section by the position detection signal 17a is only between the dotted lines 16c and 16d, and this section is 120 degrees. It is good to rank. Therefore, there is exactly the same effect as the energization between the dotted lines 16a and 16b described above.

Next, FIG. 5 will be described. Flat plate made of aluminum 27
Is a cooling fin for dissipating heat from a heating element such as a power transistor of an electronic device. The cooling fins have a large number of upright fins that are erected on the upper surface of the cooling fins to radiate heat through natural convection of air.

The heat radiation due to natural convection is not so large because the air velocity is small, so that the cooling fin becomes large. Naturally, the weight also increases.

The device of the present invention is characterized in that the above-mentioned drawbacks can be eliminated.
Next, the explanation will be given.

In FIG. 5, a hole 27a is provided in the central portion of the flat plate 27, and the electric motor M of FIG. 1 is embedded and fixed inside the hole 27a so that the fan is on the upper surface. In this case, the ring 3a in FIG. 1 has been removed.

The electric motor M is mounted by fixing the circumferential portion of the side plate 1 of FIG. 1 to the outer periphery of the bottom surface of the hole 27a.

Although not shown, the rotation of the fans 8a, 8b, ... Blows the airflow in the directions of arrows A and B in FIG. The same purpose can be achieved by configuring the fans 8a, 8b, ... As radial fans.

Symbols 28a, 28b, ... Show aluminum fins protruding upward. All other dotted lines are aluminum fins.

The above-mentioned aluminum fins are all fins protruding upward, but since the known aluminum fins dissipate heat by natural convection and temperature radiation, they are aligned in one direction, that is, in the vertical direction. In this embodiment, the air flow is represented by arrows J and K.
Since cooling is performed in the direction, that is, in the radial direction, by blowing through the fins 28a, 28b, ..., The cooling effect is increased when the fins are randomly arranged as shown by the dotted line.

With the above configuration, there is a cooling effect about 10 times that of the cooling fins by natural convection, and the cooling fins can be made compact and lightweight.

〔effect〕

It is possible to obtain a fan motor for cooling electronic devices, which is relatively flat and has a small diameter.

Compared to its structure, it can be manufactured at a light weight and at a low price,
Since it is a one-phase semiconductor motor, there is an effect that mechanical noise is reduced and a long service life is obtained.

Further, since the energization of a predetermined angle is cut off at the end of 180 degrees of the energization section, there is an effect that efficiency can be doubled, and there is a feature that it can be self-started.

By combining with the cooling fin, it is possible to form a cooling fin having a cooling effect of about 10 times, so that the shape of the cooling fin can be reduced in size and weight.

[Brief description of drawings]

FIG. 1 is a sectional view of the device of the present invention, FIG. 2 is an explanatory view of a fan, a side plate, an armature, etc., FIG. 3 is a time chart of output torque, position detection signal, etc., and FIG. FIG. 5 is an explanatory diagram of the cooling fin, and FIG. DESCRIPTION OF SYMBOLS 1 ... Side plate, 2 ... Rotating shaft, 3 ... Outer casing, 3a ... Torus, 4a,
4b ... Bearings, 5, 6 ... Magnet rotor, 7, 7a,
..., 7d ..., G armature coil, 8, 8a, 8b, ... Juan, 9a, 9b, ... chamber hole, 10, 10a, 10b, ..., 10d ...
Fixed armature, salient pole, 11 ... Hall element, 12a, 12b, ...,
12d ... torque curve, 13,14 ... cogging torque curve, 15 ...
Energization curve, 17, 17a ... Curve of position detection signal, 19a, 19b
... power supply positive / negative electrodes, 11a, 11b ... widening circuit, 20a, 20b ... operational amplifier, 21 ... capacitor, 22, 25a, ..., 25d ... transistor, 27 ... aluminum flat plate, 27a ... holes, M ... electric motor,
28a, 28b, ... Aluminum fin.

Claims (2)

[Claims] 1. A side plate having a first bearing in the center thereof and a ring-shaped protrusion centered on the first bearing, and an even number of salient poles whose peripheral portion is fixed to the ring-shaped protrusion of the side plate. A fixed armature provided and armature coils mounted on each salient pole; a cup-shaped rotor in which a ring-shaped magnet rotor having the same number of N and S magnetic poles as the salient poles is attached to the inside of the cup; A cup-shaped outer casing, the outer side of which is fixed to the side plate so as to house the armature and the rotor, a second bearing provided in the center of the bottom face of the outer casing, and the bottom face of the rotor. One part is fixed to the central part, is rotatably supported by the first and second bearings, and the magnetic pole surface of the magnet rotor is rotated oppositely to the salient pole surface via the air gap, and an outer casing. A fan whose central part is fixed to a rotating shaft protruding further outward and the outside of the fan is capped In so that the circular ring 1 end is inserted and fixed to the outer casing, a plurality of holes formed in the annular surface of the circular ring,
A magnetoelectric conversion element serving as a position detection element fixed to the fixed armature side in a portion adjacent to a salient pole of an adjacent armature so as to generate a position detection signal whose phase is substantially coincident with the output torque of the one-phase electric motor. A first electric circuit for obtaining a position detection signal by linearly increasing the output from the N and S magnetic poles of the magnet rotor of the conversion element; a capacitor charged by the position detection signal; A second electric circuit for obtaining an output voltage with a charging voltage reduced at a set ratio, and first and first electric circuits for respectively comparing the output voltage of the circuit and the odd-numbered and even-numbered position detection signals. 2, a comparison circuit, an energization control circuit that controls energization of a one-phase armature coil by the output of the circuit to cut off a predetermined section at the end of energization, and a self-starting unit that uses cogging torque. Small electric fan unit, characterized in that it is. 2. A side plate having a first bearing at the center thereof and a ring-shaped protrusion centered on the first bearing, and an even number of salient poles having a peripheral edge fixed to the ring-shaped protrusion of the side plate. A fixed armature provided and armature coils mounted on each salient pole; a cup-shaped rotor in which a ring-shaped magnet rotor having the same number of N and S magnetic poles as the salient poles is attached to the inside of the cup; A cup-shaped outer casing, the outer side of which is fixed to the side plate so as to house the armature and the rotor, a second bearing provided in the center of the bottom surface of the outer casing, and the bottom surface of the rotor. One part is fixed to the central part, is rotatably supported by the first and second bearings, and the magnetic pole surface of the magnet rotor is rotated oppositely to the salient pole surface via the air gap, and an outer casing. The fan whose center is fixed to the rotating shaft protruding further outward and the output torque of the one-phase motor In order to generate a position detection signal whose phase is substantially the same as that of the magnetic field, a magnetoelectric conversion element serving as a position detection element fixed to the fixed armature side and an output of the element are provided in the adjacent portion of the adjacent armature salient poles. A one-phase semiconductor electric motor for controlling the energization of the armature coil to drive the rotor, and a fin that rotates synchronously with the rotor to let out an air flow in the radial direction, and the electric motor were housed in a central hole. A small electric fan device comprising a cooling fin and a plurality of fins set up in the cooling fin so that the air flow passes between the cooling fins.