JP2012157116A - Dc motor with brush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC motor with a brush which safely and securely makes a conductive connection between commutator segments and a varistor without soldering the commutator segments to the varistor.SOLUTION: A DC motor with a brush includes a commutator and a varistor having electrodes and is formed by joining the commutator to the electrodes of the varistor. The commutator is joined to each electrode of the varistor by using a wire spanning the commutator and the electrode of the varistor.

Description

  The present invention relates to a brushed DC motor, and more particularly to a brushed DC motor capable of safely and reliably conducting a commutator segment and a varistor.

  In a brushed DC motor, an armature core is generally mounted on a rotating shaft, a predetermined number of windings are wound around the armature core to form an armature coil, and a commutator is mounted on the rotating shaft.

  In a DC motor with a brush having this commutator, for example, sparks are generated by a high voltage induced by the intermittent connection between the commutator and the brush during rotation, causing brush consumption and noise generation. In order to prevent this, a technique of connecting a varistor to the commutator segment is known, and an annular varistor is fitted on the outer periphery of the commutator segment and joined. Conventionally, the commutator and the varistor are joined by soldering. However, in the case of soldering, there is a problem that solder balls are generated and it takes time to remove them.

  On the other hand, in Patent Document 1, in order to solve this soldering problem, the inner diameter of the ring varistor is set to the outer diameter of the commutator in a configuration in which the inner periphery of the ring varistor is fitted to the outer periphery of the commutator without soldering. An invention is disclosed in which the outer peripheral surface of the commutator and the electrode on the inner peripheral surface of the ring varistor are brought into close contact with each other by making the size slightly smaller.

JP-A-8-14314

  However, in the invention described in Patent Document 1, when the commutator and the varistor are tightly inserted, it is likely to cause cracking of the varistor.

  In the invention described in Patent Document 1, the commutator and the varistor electrode are joined only by contact energization. However, in this case, when the motor is subjected to vibration or impact, there is a risk of causing contact failure.

  Moreover, the process of assembling a conventional armature (rotor) includes mounting a commutator on the armature core, winding a coil around the armature core, tying the coil around the commutator terminals, and commutator terminals and coils. After that, the varistor was mounted on the commutator, and the commutator and the varistor were joined with the solder. With this conventional method of assembling a rotor for soldering, the work flowed in series, so the time could not be reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a brushed DC motor capable of safely and reliably conducting a connection without joining a commutator segment and a varistor with solder. .

  In order to solve the above problems, the present invention is a brushed DC motor comprising a commutator and a varistor having an electrode, and joining the commutator and the electrode of the varistor, The connection with the electrode of the varistor is performed by a wire extending between the commutator and the electrode of the varistor.

  ADVANTAGE OF THE INVENTION According to this invention, the DC motor with a brush which can carry out the conductive connection safely and reliably without joining a commutator segment and a varistor with solder can be provided.

  Further, according to the present invention, since solder is not used, the solder ball removing operation is not necessary.

  In addition, according to the present invention, an unnecessary load such as excessive pressure or heat from solder is not applied to the varistor, so that cracking hardly occurs.

  Further, according to the present invention, the commutator and the varistor can be assembled in a sub-process (a process in which a parallel operation can be performed), which leads to a reduction in time of the main rotor assembly process.

It is a perspective view which shows one Embodiment of the rotor of the DC motor with a brush by this invention. It is a fragmentary longitudinal cross-section which shows one side of the commutator unit 5 in the rotor 1 of the DC motor with brush shown in FIG. It is a figure which shows the commutator segment shown in FIG. 1, (a) is a perspective view shown by the arrangement | positioning which combines three commutator segments on the outer periphery of the base 6, (b) is the one side of (a). It is a partial longitudinal cross-sectional view shown with a cross section. FIG. 4 is a cross-sectional view of the commutator unit 5 shown in FIG. 2 taken along the line IV-IV, in which the varistor 9 is viewed from below so that an electrode 9a can be seen.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of a rotor of a brushed DC motor according to the present invention.

  In this rotor 1, a commutator unit 5 and an armature core 2 are provided on a shaft 4 that is a rotating shaft of a brushed DC motor. The armature core 2 is formed by stacking a required number of punched three-slot magnetic plates, and the armature coil 3 is wound corresponding to each slot.

  The present invention does not depend on the number of slots of the motor, and in this embodiment, a three-slot brushed DC motor is taken as an example.

  A base 6, which is a cylindrical insulator (for example, made of resin) in which a small-diameter cylindrical body portion 6 a and a large-diameter disk portion 6 b are continuously formed, is fitted into the shaft 4. Three commutator segments each including a commutator piece 7 and a riser 8 are provided on the outer periphery of the base, and an annular varistor 9 serving as a protective element is provided on the outer periphery. A washer 10 is provided to secure the commutator segments.

  Each of the three commutator segments is provided with a riser portion 8, and the terminal portion 3 a of the armature coil 3 is electrically connected to the riser portion 8 in order to energize the armature coil 3 via the commutator piece portion 7. Connect.

  As will be described in detail later, the varistor 9 has three electrodes 9a (see FIG. 4) that are the same as the number of risers 8 at positions corresponding to the three risers 8, respectively. The position of the varistor 9 in the axial rotation direction (circumferential direction) is adjusted so that the electrode 9a is aligned with the position of the riser unit 8, and in this state, the electrode 9a and the riser unit 8 are joined together by a wire 12 to be described later in detail. . This ensures electrical connection between the varistor 9 and the three commutator segments.

  The permanent magnet disposed opposite to the rotor 1, the brush for supplying an electric current from the outside, and the bearing for fixing the rotor are the same as the configuration of a general brushed DC motor. Therefore, explanation and figures are omitted.

  FIG. 2 is a partial longitudinal sectional view showing a cross section of one side of the commutator unit 5 in the rotor 1 of the brushed DC motor shown in FIG. The left side of FIG. 2 is a side view, and the right side is a cross-sectional view at the position of the riser unit 8.

  The base 6 has a small-diameter cylindrical body portion 6a and a large-diameter disc portion 6b, and has a groove (riser portion holding portion) 6d into which the riser portion 8 is fitted when the commutator segment is inserted.

  3 is a diagram showing the commutator segment shown in FIG. 1, (a) is a perspective view showing an arrangement in which three commutator segments are combined on the outer periphery of the base 6, and (b) is (a) It is a partial longitudinal cross-sectional view which shows the one side of FIG. The left side of FIG. 3B is a side view, and the right side is a cross-sectional view at the position of the riser unit 8.

  At the tip of the riser portion 8, there is a bent portion 8a bent downward as shown in the figure. The bent portion 8a is separated from the varistor 9. For example, even when the diameter of the varistor 9 is large and the vicinity of the tip of the riser portion 8, the end portion 3a of the armature coil 3 is connected to the bent portion 8a. It is possible to facilitate the work of binding. The bent portion 8a and the terminal portion 3a entangled with the bent portion 8a are joined by, for example, arc welding to form the melted portion 11.

  4 is a cross-sectional view of the commutator unit 5 shown in FIG. 2 taken along the line IV-IV, and is a view of the varistor 9 seen from below so that the electrode 9a can be seen.

  In the present embodiment, as described above, the varistor 9 has the same three electrodes 9a as the number of the riser portions 8 at positions corresponding to the three riser portions 8, and the three electrodes Each of 9a and each of the riser portions 8 aligned in the axial rotation direction are joined by wire bonding using a wire 12.

  Next, the manufacturing method of the rotor 1 of this embodiment is demonstrated.

(First step)
First, for example, silver (Ag) is vapor-deposited on the varistor 9 (the lower surface in FIG. 2) to form the electrode 9a. The material of the electrode 9a may be gold (Au) or copper (Cu). However, silver is desirable because gold is expensive and copper is easily oxidized and costs equipment.

(Second step)
On the other hand, the commutator unit 5 is configured by combining and arranging three commutator segments including the commutator piece 7 and the riser 8 on the base 6. The riser portion 8 of each commutator segment is fitted into the groove 6 d of the base 6.

  Subsequently, the commutator unit 5 and the varistor 9 are fixed by using, for example, an adhesive (epoxy adhesive) or press-fitting.

(Third step)
Next, in order to connect the riser unit 8 and the varistor 9, wire bonding is performed using the wire 12.

  Referring to FIG. 4, in the present embodiment, three electrodes 9a having a shape obtained by curving a rectangle along the circumference are provided on the lower surface of the varistor 9, and the circumferential direction of each of the three electrodes 9a is substantially the same. A radial riser portion 8 is disposed in the center, and wire bonding is performed using the wire 12. The wire 12 is a metal wire such as gold, aluminum, or copper. As predetermined conditions for the wire bonding, for example, by setting conditions such as an ultrasonic output of 500 mW, an output time of 300 msec, and a pressure of 500 mN, the electrode and the wire can be coupled. Since the conditions differ depending on the material forming 9a, the conditions are appropriately set as appropriate.

  That is, first, the end of the wire 12 is placed on the electrode 9a, joined to the electrode 9a under a predetermined condition to form the joined portion 12a, and then the wire 12 is placed on the riser portion 8, Bonding to the riser portion 8 under a predetermined condition to form a bonding portion 12b, further placing the wire 12 on the electrode 9a, bonding to the electrode 9a under a predetermined condition to form a bonding portion 12c, Disconnect. By performing this process on the three commutator segments, the electrode 9a and the riser unit 8 can be joined by the wire 12 and can be energized.

  In this embodiment, the riser 8 and the varistor 9 are joined at three points (each electrode is joined by two wires), so that even if one wire becomes poorly connected, another wire is connected. Since it is energized, there is no conduction failure.

  When a high current is applied to the motor, the number of wires joining the riser unit 8 and the varistor 9 is increased from two to reduce the current flowing through each wire, thereby reducing the current load applied to the wires. be able to.

  Moreover, by increasing the number of wires from two, poor conduction is less likely to occur and the reliability against poor connection is increased.

(Fourth process)
After wire bonding of the three commutator segments, each wire 12 is sealed with resin. For example, a resin that hardly generates curing stress is dropped on the wire 12 and cured under predetermined conditions (for example, a temperature of 80 ° C. and a curing time of 1 hour).

(Fifth step)
Further, in a step different from the above-described steps 1 to 4, a silicon steel plate is punched into a planar shape, a plurality of these are laminated to produce an armature core 2, and the armature core 2 is inserted and fixed to the shaft 4.

  Further, insulators are put on both surfaces of the armature core 2. However, this insulator is not necessary when the armature core 2 is provided with an insulating coat.

(Sixth step)
The member produced in the fourth step is fixed to the member produced in the fifth step by press-fitting or an adhesive, and the armature coil 3 is wound around each of the plurality of salient poles of the armature core 2. The end 3 a is entangled with the bent portion 8 a at the tip of the riser portion 8.

(Seventh step)
Subsequently, the bent portion 8a and the terminal portion 3a entangled with the bent portion 8a are joined together by, for example, arc welding to form the melted portion 11.

  Thus, the rotor 1 is completed.

  Although the brushed DC motor according to the present invention has been described above, the present invention is not limited to this description, and it goes without saying that various modifications and combinations can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Armature core 3 Armature coil 4 Shaft 5 Commutator unit 6 Base 7 Commutator piece part 8 Riser part 9 Varistor

Claims (4)

A brushed DC motor comprising a commutator and a varistor having an electrode, wherein the commutator and the electrode of the varistor are joined together,
A brushed DC motor characterized in that the commutator and the electrode of the varistor are joined by a wire that extends between the commutator and the electrode of the varistor.   2. The brushed DC motor according to claim 1, wherein the commutator and the electrode of the varistor are joined by wire bonding.   3. The brushed DC motor according to claim 2, wherein the wire bonding is performed by connecting one wire from the varistor electrode to the commutator, and further to the varistor electrode and joining at three points. 4. .   The brushed DC motor according to any one of claims 1 to 3, wherein the commutator and the armature coil are joined by arc welding.

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