JPS63274344A - Commutator type rotary electric machine - Google Patents

Abstract

PURPOSE:To prevent burning due to overheating by forming at least one part of brushes conducting electricity through an armature while being slid and brought in contact with a commutator bar by a shape memory member, deforming the brushes when heat is generated by overcurrents and separating the brushes from the commutator bar. CONSTITUTION:A plurality of commutator bars 17 are mounted around a shaft 10 through an insulator 18, and connected to a rotor winding. Brushes 10 are slid and contacted in order to conduct electricity through the rotor winding. The brushes 19 consist of sliding contacting members 21 and thermal responding sections 20, and set up to a lower end plate 3 composed of an insulating material by screws 22 and are connected to a power supply. The thermal responding sections 20 are shaped by a non-return type shape memory alloy, and cushion materials 24 for vibrationproofing are attached. When a rotor is locked for some reason and brought to the state of overload during operation and overcurrents flow and the temperature of the rotor is brought to a fixed temperature, the thermal responding sections 20 are deformed, and the sliding contact sections 21 are separated from the commutator bars 17 and conduction is stopped. Accordingly, the lowering of insulating properties and burning due to over-heating are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a commutator type rotating electric machine having a protection function against overcurrent.

(Prior Art) Conventionally, for example, in a commutator motor, 1,000 commutator pieces are arranged in an annular shape on a rotor equipped with an armature coil, each commutator piece is connected to the armature coil, and the rotor is fixed. The brush provided on the commutator was configured to slide into contact with the commutator piece.

(Problems to be Solved by the Invention) In the conventional configuration described above, when the rotor becomes locked for some reason during operation or becomes overloaded 4-near, the current flowing through the armature coil becomes excessive. As a result, there was a risk that the armature coil would overheat, deteriorating its insulating coating and lowering its insulation properties, or in the worst case, burning out the electric machine's female coil.

The present invention aims to solve these problems,
Therefore, the object is to provide a commutator-type rotating electric machine that can prevent the armature coil from becoming overheated and prevent insulation from decreasing or burning out due to overheating.

[Configuration of the Invention (Means for Solving Problems)] A commutator type rotating electric machine of the present invention has at least a part of the brush formed of a shape memory member, and when an overcurrent flows through the brush, the brush is The structure is such that the temperature rises due to self-heating and deforms so as to separate from the commutator piece.

(Function) If the rotor becomes locked or overloaded for some reason, the current flowing through the brushes to the armature coil becomes excessive. Due to the overcurrent at this time, the brush self-heats and its temperature rises, but since at least a part of the brush is formed by the shape memory effect, the brush moves away from the commutator piece due to the shape memory effect as the temperature rises. The armature coils are deformed so as to be separated, and the current to the armature coils is cut off.

(Example) Hereinafter, an example in which the present invention is applied to a DC commutator motor will be described with reference to FIGS. 1 to 6. First, in FIG. 2 showing a longitudinal cross-sectional view of the entire motor, reference numeral 1 denotes a cylindrical motor frame, and a field magnet 2 is fixedly connected to the inner peripheral surface of the motor frame. A bearing fitting cylindrical portion 4 is formed at the center of the lower end plate 3 attached to the lower end surface of the motor frame l, and a bearing 5 is fitted into this bearing fitting cylindrical portion 4.

Further, a bearing fitting t71 portion 7 is also formed at the center of the upper end plate 6 integrally formed on the upper end surface of the motor frame 1, and a bearing 8 is attached to this bearing fitting cylindrical portion 7. and,
A rotating shaft 10 of a rotor 9 is rotatably inserted into and supported by both bearings 5 and 8. Reference numeral 11 denotes a rotor core with one thorny blue on the rotating shaft 10. An insulating layer 12 is formed on the surface of the rotor core by, for example, baking treatment of insulating powder, and three armature coils 13 are wound in the slots Ila. There is. and,
A collar 14 and a washer 15 are fitted onto the rotating shaft 10 from both sides of the rotor core 11. A varistor 16 is attached to the washer 15 on the lower side. For example, three commutator pieces 17 are provided below the varistor 16, and each commutator piece 17
is formed in an arc shape as shown in FIG.
It is fixed to the outer circumferential surface of a cylindrical body 18 made of an insulating material, which is attached one length to the outside. Each of these commutator pieces 17 is connected to the armature coil 13 and the varistor 16 as shown in FIG. On the other hand, in FIG. 1, reference numeral 19 denotes a pair of brushes arranged symmetrically on both sides of the commutator piece 17, and each brush 19 includes a thermally responsive part 20 formed in a plate shape from a shape memory member, and a thermally responsive part 20 formed of a shape memory member. A mounting piece 20a formed at the base of the thermally responsive part 20 is fastened to the lower end plate 3 of the motor frame 1 with screws 22. In this case, an irreversible (non-returnable) shape memory alloy is used as the shape memory member constituting the thermally responsive part 20, and the shape once deformed due to the shape memory effect accompanying temperature rise is
It is designed so that it does not return to its original shape even if the temperature drops. Further, the thermally responsive part 20 and the screw 22 are connected to the lower end plate 3.
The thermally responsive portion 20 is electrically insulated and connected to a power source 23 (see FIG. 3) via a screw 22. Therefore, in a normal operating state (a state in which the temperature of the thermally responsive part 20 does not reach the deformation start temperature T shown in FIG. 4), the thermally responsive part 20 of the brush 19 is in a straight line as shown by the solid line in FIG. The sliding contact portion 21 extends to
is in sliding contact with the commutator piece 17. On the other hand, when the temperature of the thermally responsive part 20 rises above the deformation start temperature T, the thermally responsive part 20 separates the sliding contact part 21 from the commutator piece 17 as shown by the two-dot chain line in FIG. 1 due to the shape memory effect. It has a structure that bends and deforms in the shape of a "<" character. The bending angle θ at this time is approximately 45″.
A cushion shrine 24 for vibration isolation is attached to the base side of 0.

Next, the operation of the above configuration will be explained. In normal operating conditions, that is, in operating conditions where the load is below the rated value, the brush 1
9 extends in a straight line as shown by the solid line in FIG. 1, and the sliding contact portion 21 is in sliding contact with the commutator piece 17. In this state, current flows from the electric current 23 to the armature coil 13 through the brushes 19 and commutator pieces 17, which generates torque between the armature coil 13 and the field magnet 2, causing the rotor 9 to rotate. do. On this occasion,
The armature coil 13 and brush 19 self-heat due to the current flowing inside them, but during normal operation, the current value is suppressed below the rating, so a 1M degree increase in the armature coil 13 and brush 19 is As shown in FIG. 5, the temperature of the armature coil 13 is kept low by the cooling effect of natural heat radiation, and as a result, the temperature of the armature coil 13 never reaches the guaranteed heat resistance temperature (for example, 180'C). The temperature of the thermally responsive part 20 of the brush 19 during this normal operation does not reach the deformation start temperature T (for example, 130°C), so the thermally responsive part 20
0 continues to be in sliding contact with the sliding contact portion 21 or the commutator piece 17 while maintaining the state of extending in a straight line.

On the other hand, if the rotor 9 becomes locked for some reason or becomes overloaded during operation, the brush 1
The current flowing to the armature coil 13 via the armature coil 9 becomes excessive. In this case, the self-heating of the armature coil 13 and the brush 19 becomes excessive, and the temperature rise of both becomes large as shown in FIG. However, when the temperature of the thermally responsive part 20 of the brush 19 reaches the deformation start temperature T, the thermally responsive part 20 made of a shape memory material deforms due to the shape memory effect, as shown by the two-dot chain line in FIG. Similarly, the sliding contact portion 21 is connected to the commutator piece 17.
It is bent at an angle of about 45 degrees in a "<" shape so as to be separated from the center. The relationship between the bending angle θ of the thermally responsive portion 20 and the temperature at this time is shown in FIG. 4, and as the temperature increases, the thermally responsive portion 20 deforms in the manner shown by the rightward arrow. Due to this deformation, the power to the armature coil 13 is cut off, and thereafter the temperature of the armature coil 13 decreases due to heat radiation. As a result, the temperature rise of the armature coil 13 is suppressed to below the guaranteed heat resistance temperature, and deterioration and burnout of the insulating wave film of the armature coil 13 due to overheating are prevented. In this example, since an irreversible (non-returnable) shape memory alloy is used as the shape memory member constituting the thermally responsive part 20, once the
The shape of the thermally responsive part 20, which has been bent and deformed into a ``'' shape, does not return to its original straight shape even when the temperature drops, as shown by the left-pointing arrow in FIG. Energization to the child coil 13 is blocked. In this way, the thermally responsive section 20
By maintaining the bent female shape state even after the temperature drops, the user can definitely know that an overcurrent has flowed through the armature coil 13, and the user is always given an opportunity to investigate the cause. It will be done.

In this case, if the user bends the heat-responsive part 20 back into a straight line and brings the sliding part 21 into sliding contact with the commutator j) 17, the operation becomes possible, and the overcurrent will flow again during subsequent operation. At that point, the thermally responsive portion 20 bends and deforms again, and the power to the armature coil 13 is cut off.

In the above embodiment, an irreversible (non-returnable) shape memory alloy is used as the shape memory member constituting the thermally responsive section 20, but the present invention is not limited to this. )+1i type) shape memory member may be used. In this case, the relationship between the bending angle θ of the thermally responsive part 20 and the temperature is as shown in FIG.
H, it bends and deforms in the manner shown by the rightward arrow, and then returns to deformation in the manner shown by the leftward arrow as the temperature decreases. Therefore, even if the thermally responsive part 20 is once bent and deformed, it returns to its original straight shape due to a subsequent temperature drop, brings the sliding contact part 21 into sliding contact with the commutator piece 17, and stops energizing the armature coil 13. make it possible. For example, when a motor equipped with such a reversible brush is installed in an electric fan, if a curtain or the like in the room gets entangled with the blower blades and becomes locked, the brush bends and deforms and the motor stops. By simply untangling the brush, the brush returns to its original deformation and normal operation becomes possible, which has the advantage of saving the user the trouble of bending the brush back.

The scope of application of the present invention is not limited to the DC commutator motor as in the embodiments described above, but can be widely applied to, for example, AC commutator motors, commutator generators, and other commutator-type rotating electric machines. Further, in the above embodiment, the proximal end side (thermal responsive part 20) of the bow bow 19 is formed of a shape memory material, but the distal end side (sliding contact part 21) may be formed of a shape memory material. ,
Historically, the entire brush may be integrally formed with a shape memory member.

In addition, the present invention can be modified in various ways without departing from the scope of the invention, such as by appropriately changing the shape of the brush 19.

[Effects of the Invention] As is clear from the above description, the present invention has a structure in which the brush is deformed so as to be separated from the commutator piece due to the shape memory effect accompanying temperature rise, and the current to the armature coil is cut off. Because of this, it is possible to prevent the armature coil from becoming overheated, and it has the excellent effect of preventing insulation deterioration and burnout due to overheating.

[Brief explanation of the drawing]

1 to 6 show an embodiment in which the present invention is applied to a DC commutator motor, and FIG. 1 is a cross-sectional view taken along line 1-1 in FIG. is a longitudinal sectional view, Fig. 3 is an electrical connection diagram of the armature coil, Fig. 4 is a deformation characteristic diagram of the thermally responsive part of the brush, and Fig. 5 is the thermal response of the armature coil and brush during normal operation 11. FIG. 6 is a diagram corresponding to FIG. 5 in an abnormal state, and FIG. 7 is a diagram corresponding to FIG. 4 showing another embodiment of the present invention. In the drawing, 13 is an armature coil, 17 is a commutator piece, 19 is a brush, 20 is a thermally responsive part, and 21 is a JF7 contact part.

Claims (1)

[Claims] 1. In a device in which the armature coil is energized by bringing the brush into sliding contact with the commutator piece, at least a part of the brush is formed of a shape memory member, and when an overcurrent flows through the brush, the brush 1. A commutator-type rotating electrical machine characterized by having a configuration in which the commutator pieces are deformed so as to increase in temperature due to self-heating and move away from the commutator pieces.