JPS6318438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronous motor, and more particularly, to a synchronous motor that can be realized at low cost by simply changing the arrangement of brushes relative to a commutator and the arc width of the brushes as a means for extremely smooth switching when switching to synchronous operation. Regarding synchronous motors with no energy loss.

The inventor has already developed a motor in which a combination of a commutator, a commutator, and a brush is used to start up the rotor to bring it up to synchronous rotation, and at that point, the commutator and commutator are removed from the circuit and the motor is switched to synchronous operation using AC power. In order to shorten the start-up period at start-up, full-wave rectification of AC power is supplied to the coils of the fixed armature, and the torque at start-up is greater than the torque required during synchronous operation to switch from start-up to synchronous operation. In order to ensure reliable switching and synchronized operation with the minimum amount of power required, the armature coil is branched into two, and during startup operation, full-wave rectified power AC is alternately supplied to each coil segment, resulting in synchronized operation. At times, he invented and applied for a synchronous motor that directly supplied AC power to the entire coil (Japanese Patent Application No. 159711 (1983) (Japanese Unexamined Patent Publication No. 63061/1989), Japanese Patent Application No. 159712 (1983)). 58-63062)).

However, in this type of electric motor, during startup operation, due to rectification, only the current corresponding to the rotation angle of the rotor is supplied to coil A of the branched armature coils A and B, for example. The other B coil is always supplied with a current component opposite to that of the A coil, so current flows in the same direction in both coils, and as the rotor rotates, the commutator acts so that the overall direction of the current flowing through both coils is As shown in Figure 1, as the cycle of this conversion gradually becomes faster and approaches the cycle of the AC power supply, the current is biased towards one of the coils (coil A in the figure). The probability of each becoming flowing is 50%. When the current converges in coil A, the flowing current overlaps with the AC phase, so operation continues even when switching to synchronous operation. However, when the current converges on coil B, the flowing current overlaps the AC phase. Since the opposite torque is generated and the switch to synchronous operation occurs, the operation returns to starting operation again, and the current flows to coil A.
Until it converges, the system will have to go back and forth between startup operation and synchronous operation, which will cause mechanical noise due to the removal of the commutator, etc., making it impossible to expect smooth switching.

In order to solve the above-mentioned difficulties, the inventor has developed a coil A.
Coil A by making the number of turns of coil A smaller than the number of turns of coil B.
By making the resistance value of coil B smaller than the resistance value of coil B, or by adding a separate resistance to coil B, sufficient torque conditions commensurate with the load are given to coil A to switch to synchronous operation, and the other coil By giving B a torque condition insufficient to switch to synchronous operation, the desired state is achieved by providing a torque condition that is insufficient to switch to synchronous operation, so that it switches to synchronous operation only when the positive current converges in coil A, where a positive current with the same phase as the power supply AC flows. We achieved the goal of ensuring a smooth transition from start-up operation to synchronous operation and filed a patent application (Japanese Patent Application No. 177740/1983 (Japanese Patent Application Laid-open No. 79457/1983)).

Here, the inventor attempted to improve the above invention by taking into consideration the increase in cost and energy loss caused by intentionally adding resistance to one of the coils. It was found that the intended purpose could be easily achieved.

That is, an object of the present invention is to provide a coil for a 4-pole permanent magnet rotor that can be operated as a synchronous motor using an AC power source, which can eliminate the problems that occur when switching to synchronous operation by an extremely simple and inexpensive means. A fixed armature is provided, which divides the coil into two coil segments, and during start-up operation until synchronous operation is reached, the power supply AC is rectified to transfer the positive current component of the AC to one coil segment, and the negative current component of the AC to one coil segment. Rectification for alternating the direction of current flowing in the same direction in the coil as a whole so as to cause current components to flow in the same direction to the other coil segments and to bias the rotation of the rotor as the rotor rotates. A conversion circuit consisting of a commutator, a commutator, and a brush is provided, and this conversion circuit includes:
In a synchronous motor provided with a switching means for removing the conversion circuit and switching to synchronous operation when the rotational speed of the rotor reaches around the rotational speed of synchronous operation,
To provide one A coil segment with a sufficient torque condition commensurate with the load to switch to synchronous operation, and to provide the other B coil segment with an insufficient torque condition to switch to synchronous operation.
Two sliding ring pieces with a circumferential angle slightly smaller than 180° are installed in the commutator, and four brushes are in sliding contact with these sliding ring pieces from four sides, and these brushes are directly connected to the A coil segment. The main brush has two switching brushes that are located on both sides of the circumference of the brush (referred to as the main brush) and communicate with the main brush via a sliding ring piece to form a circuit including the power supply and the A coil segment. The brushes are arranged slightly closer to each other in the circumferential direction, and the sub-brush, which directly communicates with the remaining B coil segments, is arranged symmetrically with respect to the main brush with respect to the central axis, and the arc width of the main brush is made uniform with that of the other three brushes. In relation to the width of the brush, the expansion angle of the sliding ring piece, and the installation angle in the circumferential direction of the brush, such as making it larger than the arc width, the rotation angle of the rotor that energizes the A coil segment in a certain polar state becomes the B segment. To provide a synchronous motor characterized in that the rotation angle of the rotor is always set to be larger than the rotation angle of the energized rotor. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is an explanatory diagram of the commutator and circuit of the present invention, and 10 is an armature coil, which is composed of coil segments 10a and 10b.

Reference numerals 12a, 12b, 12c, and 12d are brushes, respectively, which are in sliding contact with the sliding ring 14 (collectively referred to as brushes 12).

The brushes 12a and 12b each have a commutator 16.
a, 16b communicates with the power supply 18 and further between coil segments 10a and 10b. Brushes 12c and 12d also communicate with the free ends of coil segments 10a and 10b, respectively.

The sliding ring 14 consists of sliding ring pieces 14a and 14b that are divided into two parts around the rotating shaft 15 of the motor with a circumferential angle slightly smaller than 180 degrees.

Switches 20a and 20b operate in the direction of the broken line and simultaneously remove the commutator and commutators 16a and 16b, which are composed of the sliding ring 14 and the brush 12, and connect the AC power source 18 and the coil segment 10.
The armature coil 10 short-circuits a and 10b in series.

In the state shown in Figure 2, the power supply 18 and commutator 16
a, the circuit of the brush 12a, the sliding ring piece 14a, the brush 12c, the coil segment 10a, the power supply 18, and the state in which the sliding ring is slightly rotated, the power supply 18, the coil segment 10b, the brush 12d,
Sliding ring piece 14b, brush 12b, commutator 16
b. Configuring the circuit of the power supply 18.

Here, when the sliding ring 14 rotates approximately 90 degrees counterclockwise, the brushes 12a and 12d move the sliding ring pieces 1
4a, and the brushes 12b and 12c are connected via the sliding ring piece 14b, and the power supply 18, the switch 20a, the commutator 16a, the brush 12a, the sliding ring piece 14a, the brush 12d, the coil segment 10b, and the switch 20b. circuit and power supply 18, switch 20b, coil segment 1
0a, brush 12c, sliding ring piece 14b, brush 12b, commutator 16b, switch 20a, and power supply 18 constitute a circuit.

Thus, in the armature coil 10, when the sliding ring 14 is in the state shown in FIG. 2, alternating current rectified current flows alternately and in the same direction with respect to the coil segments 10a and 10b. In this case, the current flows only through one of the coil segments, so a larger current flows than when all coils are energized, and a larger torque is generated at startup than during synchronous operation. When the sliding ring 14 rotates together with the rotating shaft of the motor, the direction of the current flowing through the armature coil 10 changes every time the sliding ring 14 rotates about 90 degrees, and the polarity is changed.

Therefore, the poles of the four-pole permanent magnet rotor and the fixed armature correspond, and each time the rotor rotates approximately 90 degrees, the poles of the fixed armature change, acting to continue to urge the rotor to rotate.

Next, when the rotational speed of the rotor reaches around synchronous rotation, the commutator and commutator are removed, and at the same time switches 20a and 20b are switched as shown by the broken line, and the power supply and armature coil 10 form a short circuit. However, the motor is driven as a synchronous motor.
In this case, since the armature coil 10 has coil segments 10a and 10b connected in series,
The current flows to the limit that generates the torque necessary for synchronous operation commensurate with the load.

Here, the brushes 12a, 12b, 12c, 12
d is arranged at approximately the quadrant position, but the brush 12
a and 12b are arranged on the circumferential brushes 12 so that the circumferential angle between them and the brush 12c is smaller than 90°.
Brush 1 is provided closer to the direction of c.
The arc width of 2c is the same as that of the other three brushes 1 with uniform arc width.
It is made larger than 2a, 12b, and 12d.

For example, as shown in FIG. 3, if the brushes 12a and 12b are shifted by α° from the regular quadrant position in the direction of the brush 12c, and the width of the brush 12c is extended by β° to the left and right at the circumferential angle, Sliding ring 14
a or 14b rotates while bridging between the brushes 12b and 12c or between the brushes 12c and 12a, and the circumferential angle at which the current is applied is (α+
β)° becomes larger, and α° between the brushes 12a and 12d or between the brushes 12d and 12b becomes smaller than when the brushes are at the regular quadrant positions.

By setting the sizes of α and β in this way, the brushes 12b and 12c or the brushes 12c and 12
The time during which a is electrically conductive through the sliding ring 14 is determined by the brushes 12a and 12d or the brushes 12d and 1.
2b is conductive via the sliding ring 14 for a certain period of time, a current flows through the coil segment 10a to provide enough torque to switch from start-up operation to synchronous operation. Adjust the integral value of the current so that it does not occur.

With this setting, if the rotational speed of the rotor reaches near synchronous rotation and the rectified current converges only on the coil segment 10a, the operation will switch to synchronous operation, but if the rectified current converges only on the coil segment 10b, the synchronous operation will switch to synchronous operation. Since the operation is switched to the synchronous operation when the timing to converge to the segment 10a is obtained, the operation is switched to the synchronous operation in one operation without going back and forth between the starting operation and the synchronous operation.

It goes without saying that either one of the means for bringing the brushes 12a and 12b closer to the brush 12c and the means for increasing the arc width of the brush 12c may be used.

As described above, according to the present invention, it is possible to reliably and smoothly convert start-up operation to synchronous operation by slightly changing the arrangement of the brushes or by increasing the arc width of one brush, which is extremely simple and inexpensive. play.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. FIG. 1 is an explanatory diagram showing a state in which rectified current is converged on one coil segment, FIG. 2 is an explanatory diagram of the commutator and circuit of the invention, and FIG. It is a principle explanatory diagram. 10... Armature coil, 10a, 10b... Coil segment, 12, 12a, 12b, 12
c, 12d...Brush, 14...Sliding ring, 1
4a, 14b...Sliding ring piece, 15...Rotating shaft, 16a, 16b...Commutator, 18...Power supply,
20a, 20b...switch.

Claims (1)

[Claims] 1. A fixed armature having a coil adapted to be operated as a synchronous motor by an AC power source is provided for a four-pole permanent magnet rotor, and the coil is divided into two coil segments, and a synchronous motor is provided. During start-up operation until operation is reached, the AC power source is rectified to flow the positive AC current component to one coil segment and the negative AC current component to the other coil segment, both in the same direction, and as the rotor rotates. A conversion circuit consisting of a commutator, a commutator, and a brush is provided to alternately convert the direction of the current flowing in the same direction throughout the coil so as to urge the rotation of the rotor. In a synchronous motor equipped with a switching means for switching to synchronous operation by disconnecting the conversion circuit when the speed reaches the vicinity of the rotational speed for synchronous operation, one A coil segment is connected to the load in order to switch to synchronous operation. Two sliding ring pieces with a circumferential angle slightly smaller than 180° are installed on the commutator in order to provide a sufficient torque condition for the commutator and to provide an insufficient torque condition for switching to synchronous operation on the other B coil segment. Four brushes are in sliding contact with these sliding ring pieces from four sides, and among these brushes, brushes that directly communicate with the A coil segment (referred to as main brushes) are placed on both sides of the circumference. , two switching brushes that are connected to the main brush through a sliding ring piece and constitute a circuit including a power supply and an A coil segment are arranged slightly close to each other in the circumferential direction of the main brush, and are connected to the remaining B coil segment. The width of the brush and the expansion angle of the sliding ring piece can be adjusted by arranging the secondary brush that directly communicates with the main brush in a symmetrical position with respect to the central axis, and making the arc width of the main brush larger than the uniform arc width of the other three brushes. , in relation to the circumferential installation angles of the brushes, the rotation angle of the rotor that energizes the A coil segment is always set to be larger than the rotation angle of the rotor that energizes the B segment in a certain polar state. synchronous motor.