JPS6333380B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a brushless motor device.

1 to 4 show conventional brushless motors. First, FIG. 1 is a sectional view of a main part of an outer rotor type brushless motor. As shown in the figure, this motor has a four-pole structure, in which 1 is the stator core, 2 is the winding, 3 is the rotor,
4 is a rotor magnet such as a ferrite magnet, 5 is a rotor yoke, and 6 is a Hall element. The gap length between the salient pole portions of the stator core 1 of this motor and the rotor magnet 4 gradually increases in the clockwise direction. Further, as shown in FIG. 2, the winding 2 includes a first winding 2a forming the first phase and a second winding 2a forming the second phase.
The windings 2a and 2b are simultaneously wound one on top of the other, and the windings 2a and 2b are respectively excited with opposite polarities as shown in FIG. 2B. In FIG. 2B, Tr ₁ and Tr ₂ are transistors, respectively, and B is a battery.

Thus, FIG. 1 shows a state in which no current is flowing through the winding 2, and the magnetic poles of the rotor magnets 4 are located in the narrow part of the gap and are stable. If you turn the rotor 3 a little in the CCW direction (clockwise) from this position,
Torque in the CW direction (counterclockwise) appears, and vice versa
If you turn it slightly in the CW direction, torque in the CCW direction will appear. In other words, no matter which side the rotor 3 is displaced, there is an effect of returning it to a stable point. That is,
As shown in FIG. 3, the relationship between the rotational angle θ of the rotor 3 and the torque when not energized is as shown by a curve a, and the stable points p of the rotor 3 are located at four locations during one rotation. There is a point between these stable points p where the torque is 0,
This is an unstable point and will try to rotate in either direction with the slightest external force. Next, the relationship between the torque and the rotation angle θ when current flows through the winding 2 is the first
The second windings 2a and 2b result in curves b and b' in FIG. The zero points of these curves are slightly to the right (in the CW direction) of that of curve a. When the commutation effect by the Hall element 6 and the circuit is added to this,
Since the torque is in the upper half of curves b and b', the combined torque with curve a becomes curve c. In other words, there is no torque dead center and stable operation is achieved. Although this method has a simple structure and is excellent, it has the drawback that the gap length inevitably becomes long, which tends to result in poor efficiency.

In addition, as another conventional example, an example using a complementary pole is shown in the fourth example.
As shown in the figure. In this example, the main pole 1a of the stator core 1
A commutating pole 1b is provided between the two, and a current flows through the winding 2 as shown. This method starts up reliably, but since the commutative pole 1b is always excited to the S pole,
It is thought that when the N pole on the rotor 3 side comes close to the commutative pole 1b while the motor is rotating, they attract each other, reducing the efficiency of the motor. Furthermore, there is a drawback that the presence of a large number of commutating poles 1b reduces the efficiency of winding work to the main pole 1a.

The present invention has been proposed in view of the above points, and its purpose is to provide a part of the stator core with an auxiliary winding that is always excited with a constant polarity, thereby achieving a structure in which the gap is gradually lengthened, unlike the conventional structure. To provide a brushless motor device that is highly efficient, can be easily wound around magnetic poles, can be lightweight and cost-reduced, and can be reliably started without the need to adopt a brushless motor device.

The present invention will be explained below with reference to the drawings.

FIG. 5 shows an embodiment of the present invention, in which the stator core ST has a pair of first and second magnetic poles 11a and 11c that protrude symmetrically about the rotation axis The first magnetic pole is composed of a pair of protruding third and fourth magnetic poles 11b and 11d arranged perpendicularly to each other, and is wound around the first and second magnetic poles 11a and 11c.
It is a two-phase winding consisting of the winding L ₁ and the second winding L ₂ wound around the magnetic poles 11b and 11d in Figs. 3 and 4, and the winding work is easier than with distributed winding. In addition, line processing is simplified because the number of phases is small.

Moreover, the first and third magnetic poles 11a adjacent to each other
and 11b has a third winding L ₃ which is an auxiliary winding.
is wound around the first magnetic pole 11a and the third magnetic pole 11a.
A rotor position detecting element H such as a Hall element is arranged between the magnetic poles 11b and 11b. Further, a ring-shaped rotor RT is arranged around the stator core ST in which N and S poles made of permanent magnets are arranged alternately.
b, 12c, and 12d indicate the permanent magnets of the rotor RT, respectively.

Figure 6 shows the drive circuit, in which a 60Hz or 50Hz full-wave rectified wave from the AC power supply is rectified by the rectifier _Ref , flows through the third winding _L3 and the resistor _R3 , and the resultant wave is the In Figure 5, an N pole is always formed in the direction of the arrow, and when energized, it is activated by the magnetomotive force of this N pole.

In other words, when energized, there are first and second windings _L1 and _L2 that are alternately energized depending on the position of the rotor RT, and a third winding _L3 that is always energized. The third winding _L3 provided in series with the first and third magnetic poles 11a and 11b is connected to either the N pole or the S pole (Fig. By winding the magnetic poles so that one of the first magnetic pole 11a and the third magnetic pole 11b has a large repulsive force against the rotor RT, the other magnetic pole has a large repulsive force. The rotor RT moves away from the dead center of the position detection element H and moves in either direction (the third winding
The magnetic pole formed by L ₃ is determined as N pole or S pole. ), the rotor RT starts rotating and can be started. That is, the third winding _L3 functions to smoothly start the rotor RT from the position shown in FIG.

In FIG. 6, R ₁ , R ₂ , and R ₄ are resistors, and Q ₁ and Q ₂ are transistors. After starting, the rotor RT rotates slightly clockwise in the example shown in FIG. 5, whereby the position detection element H detects the north pole of the rotor RT, turning off the transistor _Q2 shown in FIG. At the same time, transistor Q ₁ turns on and energizes the first winding L ₁ ,
The permanent magnets 12a and 12c of the rotor RT are magnetized by exciting the first and second magnetic poles 11a and 11c to N poles.
A repulsive force is generated between the rotor RT and the rotor RT.

When the rotor RT rotates and the S pole of the permanent magnet 12d of the rotor RT comes to the position detecting element H, the transistor Q ₂ turns on, and the second winding L ₂ is energized to detect the third and fourth magnetic poles. 11b and 11d are excited to become N poles, and the rotor RT permanent magnet 12
a, 12c to generate a repulsive force between the rotor
This allows the RT to continue rotating.

Note that the rotor is not in the rest position shown in Figure 5.
When RT is stationary, when the circuit shown in FIG. 6 is energized, position detection element H detects the position of rotor RT, and the transistor Q ₁ or Q ₂ determined by the relationship between the position and the rotation direction Either one of them turns on, starts in a predetermined direction, and rotates.

Note that FIG. 7 shows a case where the present invention is applied to fan F.

As described above, according to the present invention, since a part of the stator core is provided with an auxiliary winding that is always excited to a constant polarity, startup is smooth, and unlike the conventional method, a complicated structure in which the gap is gradually lengthened is adopted. There is no need to do so, and manufacturing precision is not required so much that productivity can be increased and costs can be reduced, and a motor that can always be reliably started automatically can be provided.

In addition, since the structure does not have a large number of commutating poles, the magnetic poles can be made large, and torque and efficiency can be improved. Furthermore, winding is easy and the weight of the motor can be reduced.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of a conventional brushless motor, Figure 2 is an explanatory diagram of the coil, A is a partial sectional view of the stator core, B is a wiring diagram, and Figure 3 is a partial sectional view of the stator core.
The figure is a torque characteristic diagram, Figure 4 is a schematic explanatory diagram showing another conventional example, Figures 5 to 7 are an embodiment of the present invention, and Figure 5 is an explanatory diagram of the main part. 6th
The figure is a drive circuit diagram, and FIG. 7 is a perspective view showing an application example. ST...Stator core, L ₁ ...First winding, L ₂
...Second winding, _L3 ...Third winding, H...Position detection element, 11a...First magnetic pole, 11b...
Second magnetic pole, 11c...Third magnetic pole, 11d...
Fourth magnetic pole, RT...rotor, 12a, 12b,
12c, 12d... Permanent magnets of rotor RT.

Claims (1)

[Claims] 1. A motor comprising a stator having a plurality of magnetic poles, and a ring-shaped rotor in which north and south poles are alternately arranged outside the stator with a desired gap between the stator and the stator. A pair of protruding first and second magnetic poles arranged symmetrically about the rotation axis, and a pair of protruding third and fourth magnetic poles arranged perpendicularly thereto. A first winding is provided on the first and second magnetic poles, and a third winding is provided on the first and second magnetic poles.
and a fourth magnetic pole is provided with a second winding, and a third winding is wound in series around the adjacent first and third magnetic poles, and a third winding is provided on the adjacent side of both magnetic poles. A brushless motor device comprising: a drive circuit in which a Hall element is arranged, and the first and second windings are alternately excited by the Hall element.