JPH0441748Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a DC motor, and more particularly to an improvement in an armature coil terminal tightening device for a DC motor used, for example, in a starter device for a vehicle.

(Prior Art) Conventionally, a DC motor used, for example, in a starter device for a vehicle, has been constructed as shown in FIG. That is, the conventional DC motor includes an armature core 2 attached to a rotating shaft 1 and a commutator 3 supported by the rotating shaft at the side of the armature core 2. This commutator 3 is of the so-called face type, and the contact surface 3a with the brush 4a of the brush device 4 is formed in a vertical plane perpendicular to the axis of the rotating shaft 1, and the commutator 3 is made of a synthetic resin material. It consists of a number of commutator pieces or segments 3b insulated by. Each of these segments 3b has an armature core 2
A terminal portion 5a of an armature coil (not shown) drawn out from the terminal is connected. Therefore, these terminal portions 5a are closely arranged in the circumferential direction around the rotating shaft 1 to form an annular terminal wire group 5.

A tightening ring 6 called a bind is attached to the outer periphery of this annular terminal wire group 5 in order to prevent the terminal wire group 5 from flying outward due to centrifugal force when it rotates together with the armature core 2 and commutator 3. ing. This bind 6 is generally formed by winding a piano wire 6a around the upper surface of an insulating paper 7. A ring-shaped iron plate, resin-impregnated tape, or the like may be used instead of the piano wire 6a.

In FIG. 2, reference numeral 4b indicates a holder for the brush device 4, and reference numeral 8 indicates a mold portion that supports the commutator 3 with respect to the rotating shaft 1 via an insert 9.

(Problems to be Solved by the Invention) Generally, when a DC motor is used as a starter for a vehicle, the rotation of the rotating shaft may be transmitted to the overrunning clutch via a reduction gear. In a starter having such a structure, in order to make the DC motor smaller and lighter, the reduction ratio of the reduction gear may be increased to reduce the outer diameter or core area of the armature core. However, even in this case, the size of the commutator is determined physically and it is not possible to reduce the outer diameter or axial length of the brush contact surface to correspond to the armature core. Therefore, the commutator has a relatively larger outer diameter than the armature core, and the smaller the diameter of the armature core, the faster it rotates. As a result, an extremely large centrifugal force was applied to the commutator.

In addition, not only when used in a vehicle starter, but also in normal usage, the outer diameter of the commutator, especially the segment, has sometimes been made larger than that of the armature core in order to improve the commutator state. Increasing the outer diameter of the commutator in this way increases the contact area of the brush, reduces the current density, improves the rectification state, and lengthens the life of the brush.
Even in such a case, the commutator has a relatively larger outer diameter than the armature core, so the commutator is subjected to a large force due to centrifugal force.

Furthermore, in any of the cases described above, if the commutator is a so-called face type in which the contact surface with the brush is formed on a vertical surface perpendicular to the axis of the rotating shaft, the size of the commutator is directly the dimension in the radial direction. This appears as an expansion of the centrifugal force, so the magnitude of the force received from centrifugal force becomes larger and larger. However, when a large force due to centrifugal force is applied to the commutator, the commutator segments have a problem in that the connections made by the insulating material are broken and they fly outward.

The purpose of the present invention has been made to solve these conventional problems, and is to provide a DC motor that can prevent the segments from popping out even if a large force due to centrifugal force is applied to the commutator.

(Means for Solving the Problems) The DC motor of the present invention is characterized in that it straddles the terminal portion of the armature coil and the boss-shaped portion of the commutator and fastens them with an annular bind.

(Function) According to the DC motor of the present invention, in a commutator having a brush contact surface located in a plane perpendicular to the axis of the rotating shaft, a terminal wire of an armature coil is attached to a boss-shaped portion having a smaller diameter than the brush contact surface. and the bind is arranged so as to straddle both of them, which prevents damage to the commutator due to centrifugal force, and prevents the terminal group of the armature coil and the bind itself from being subjected to large centrifugal force. can be tightly tied together and held together.

(Embodiments) Hereinafter, the DC motor of the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1 partially shows a DC motor according to an embodiment of the present invention. In FIG. 1 showing this embodiment, parts that are the same as or correspond to the components of the conventional DC motor shown in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted.

As shown in FIG. 1, the DC motor of this embodiment includes a face-type commutator 10, the diameter D ₁ of which is larger than the diameter D ₂ of the armature core 2. That is, commutator 10
is assembled by arranging L-shaped segments 10c at equal intervals in the circumferential direction and filling each interval with resin to insulate the segments from each other. Thereby, the commutator 10 is formed in a vertical plane orthogonal to the rotation axis 1, and has a contact surface 10a on which the brush 4a of the brush device 4 slides, and the contact surface 10a.
A boss-like portion 10b that projects toward the armature core 2 along the axial direction is formed on the radially inner side of a, that is, the portion that contacts the mold portion 8 that supports the commutator 10.

In this way, the face-type commutator 10 is
The contact surface 10a of the brush device 4 with the brush 4a is formed to be large, and the rectification state is improved. Further, in the commutator 10 of this embodiment, the presence of the boss-shaped portion 10 also stabilizes the attachment to the rotating shaft 1.

A terminal portion 5a of an armature coil is connected to each segment 10c of the commutator 10 having such a configuration at a boss-shaped portion 10b of the commutator 10. Boss-shaped portion 10 of commutator 10
An annular terminal wire group 5 consisting of a circumferential surface on b, that is, a stepped portion 10d, and a large number of terminal portions 5a arranged densely in an annular shape.
A bind 11 is attached to straddle the two. This bind 11 is composed of an annular iron plate, and is attached to the insulating paper 7 after wrapping the insulating paper 7 with a width spanning the boss-shaped portion 10b of the commutator 10 and the terminal wire group 5. Each segment 10c and the terminal portion 5a are tightened radially inward. The bind 11 can be formed by wrapping piano wire or resin-impregnated tape in addition to an iron plate.

With this configuration, even when the commutator 10 rotates at high speed and receives a large centrifugal force, or even when the outer diameter of the commutator is increased and a large centrifugal force acts on it, each of the commutators 10 Since the segment 10c is held down by the bind 11 at its small-diameter boss-shaped portion 10b, the centrifugal force that the bind 11 receives is small, so that the bind 11 does not break and firmly holds the segment and prevents it from jumping out. be able to.

(Effects of the invention) As explained above, according to the DC motor of the invention, in a commutator having a brush contact surface located in a plane perpendicular to the axis of the rotating shaft, a boss having a smaller diameter than the brush contact surface By connecting the terminal wires of the armature coil to the terminal wire group and installing the bind across not only this group of terminal wires but also the boss-shaped portion of the commutator, damage to the commutator due to centrifugal force can be prevented. Rather, the terminal wire group of the armature coil and the bind itself are not easily subjected to large centrifugal force, and they can be tightly bundled and held.

[Brief explanation of the drawing]

FIG. 1 is a sectional view partially showing a DC motor according to an embodiment of the present invention, and FIG. 2 is a sectional view partially showing a conventional DC motor. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Armature core, 4... Brush device, 5... Terminal wire group, 5a... Terminal part, 10
...Commutator, 10a...Contact surface, 10b...
...Boss-shaped portion, 10c...Segment, 10d...
...Stepped section, 11... Bind. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims for Utility Model Registration] (1) An armature core attached to a rotating shaft, and a commutator formed by aggregating a large number of segments in an annular shape and supported by the rotating shaft at the side of the armature core. a brush contact surface located in a plane perpendicular to the axis of the rotating shaft; and a boss-shaped portion having a smaller diameter than the outer diameter of the brush contact surface, the boss-shaped portion being drawn out from the armature core. a commutator connected to each terminal portion of the armature coil; a brush device that contacts the brush contact surface of the commutator; A DC motor including an arranged binding. (2) Registration of a utility model characterized in that the bind is constituted by any one of an annular plate made of iron, an annular body made of a large number of windings of piano wire, or an annular body made of tape impregnated with resin. A DC motor according to claim 1.