JP5257658B2 - Commutator motor armature and electric tool including the same - Google Patents

Description

  The present invention relates to a commutator motor including a coil wound in a slot of a core of an armature and a resin-coated armature in which a coil end projecting from both ends of the core is coated with a mold resin coating layer or a coating resin coating layer. And an electric tool using the same.

  In portable electric tools such as disc grinders used for grinding operations, a commutator electric motor is used as a rotational drive source because it is relatively small and light. In this electric tool, a power transmission housing portion for housing a gear, a spindle and the like for transmitting the output of the rotating shaft to a tip tool such as a grinder is provided on one end side in the rotating shaft direction of the motor housing portion for housing the commutator motor, and further the motor. Generally, a handle housing portion for storing an electric circuit such as a drive switch is provided on the other end side in the rotation axis direction of the housing portion.

  In an electric power tool, iron grinding scraps and stone cutting scraps enter the motor housing through a cooling wind window provided in the handle housing part, power transmission housing part, etc., and the winding coil protruding from the core slot There is a problem that the end portion is damaged and worn or disconnected.

  In order to prevent this problem of wear or disconnection, as disclosed in the following Patent Literature 1, Patent Literature 2, Patent Literature 3 and Patent Literature 4, the coil portion inside the core slot of the armature and the outside of the core slot are disclosed. A technique for coating a coil end portion with a mold resin layer by molding is well known. With this technique, the coil resin inside the core slot of the armature and the coil end outside the core slot are coated with a mold resin layer to a predetermined thickness. Can be prevented.

JP-A-7-123618 JP-A-8-140318 Japanese Patent Laid-Open No. 7-123642 JP 2007-166683 A

  However, when the resin mold commutator motor is used as a power source for an electric tool that causes excessive vibration in grinding operations such as a disk glider, only the vibration of the rotor itself fixed to the rotating shaft of the motor In addition, vibration caused by friction between a tip tool such as a grinder (grinding stone) and a workpiece (workpiece) is transmitted from the tip tool to the armature of the electric motor through the spindle and gear which are power transmission mechanisms. For this reason, the rotating shaft of the electric motor bends, and an excessive stress is applied to the coil end portion of the coil wound around the core of the armature, which may cause disconnection of the coil electrically connected to the commutator.

  FIG. 6 shows a structural example of a resin mold armature of a conventional commutator motor used as a power source of a disk grinder. The resin mold armature 2a includes a core 2f fixed to the rotating shaft 2d, coil end portions 2e1, 2e2, and 2e3 in which coils wound around slots (not shown) of the core 2f protrude from both ends of the core 2f. The commutator 2h and the cooling fan 2c are provided, and the coil in the slot (not shown) of the core 2f and the coil end portions 2e1, 2e2, and 2e3 are covered with the mold resin coating layer 9 by molding. As a result of applying this resin mold commutator motor to a disk glider, not only the vibration of the resin mold armature 2a itself of the motor but also the vibration caused by friction with the work material is transmitted to the resin mold armature 2a, and the rotating shaft 2d It has been found that bending, in particular, excessive stress is applied to the coil end portion 2e3, cracks are generated in the mold resin coating layer 9, and disconnection may occur at the connection between the commutator and the coil.

  This is because, in the resin mold armature as described above, the stress with respect to the bending of the rotating shaft 2d is short from the neutral surface of the rotating shaft 2d (horizontal plane crossing the axial direction X of the rotating shaft 2d). The commutator 2h concentrates on the resin layer in the vicinity of the core 2f (in the vicinity of the locations Y1 to Y2). Due to this stress, a crack occurs in the mold resin coating layer, and the coil fixed to the mold resin coating layer is easily disconnected near the coil end portion 2e3 adjacent to the commutator 2h.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a commutator motor that suppresses wear or disconnection of an armature coil having a resin coating layer in an electric motor having a resin coated armature made of a resin mold or the like. And it is providing the electric tool using the same.

In order to solve the above-mentioned problems, an invention according to claim 1 is directed to a rotating shaft, a coil wound in an axial direction of the rotating shaft in a slot of a core fixed to the rotating shaft, and the rotating shaft. A coil end portion made of the coil projecting out of the slot in the axial direction of the coil, a commutator fixed to the rotating shaft and electrically connected to the coil end portion, and a mold resin covering the entire coil In the armature of a commutator motor in which a constricted portion that is recessed toward the rotating shaft is formed in the coil end portion , elasticity is provided between the coil surface of the constricted portion and the mold resin layer. The adhesive layer which has is formed.

  The invention according to claim 2 is characterized in that the adhesive layer is formed from the connecting portion between the commutator and the coil to the constricted portion.

  According to a third aspect of the present invention, there is provided a power tool including the commutator motor armature according to the first and second aspects.

  According to the present invention, stress is concentrated in the vicinity of the commutator side of the coil end portion between the core end portion and the commutator due to excessive vibration in the armature or deformation of the rotating shaft during operation of the commutator motor. Even if a crack occurs in the mold resin coating layer, the crack is not generated in the coil because the coil is protected by an elastic adhesive. Therefore, disconnection of the coil can be completely prevented. In particular, a remarkable effect can be obtained by applying to a commutator motor of a power tool that easily generates vibration such as a disk grinder.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. Further, members having the same functions as those of the conventional resin mold armature shown in FIG. 6 are also given the same reference numerals as those shown in FIG.

[First Embodiment]
1 and 2 show a side sectional view and a top sectional view of an electric power tool in which a commutator motor according to a first embodiment of the present invention is applied to a disc grinder. First, the configuration of the entire power tool will be described with reference to FIGS. 1 and 2. The disk grinder 100 is connected to a motor housing portion 3 made of a resin material or a metal material, which houses a commutator motor 2 using a resin molded armature 2a according to the present invention, which will be described later, and one end side of the motor housing portion 3. For example, a gear cover portion 4 made of, for example, a metal material, a switch handle portion 8 that houses a switch 7 and a switch circuit (not shown) of the commutator motor 2, and a power cord 8b are provided. The commutator motor 2 housed in the motor housing part 3 includes a resin mold armature 2a fixed to the rotating shaft 2d and a stator 2b fixed to the motor housing part 3, and the output side of the rotating shaft 2d is cooled. When the cooling fan 2c is fixed and the cooling fan 2c rotates, the outside air for cooling (cooling air) is taken in from the intake air window 8a formed in the switch handle portion 8, and the cooling air is supplied to the motor housing portion 3, It passes through the gap between the resin-molded armature 2a and the stator 2b and is discharged into the atmosphere from an exhaust wind window 4a (see FIG. 2) provided in the gear cover portion 4.

  Further, in the gear cover portion 4, a first bevel gear (pinion gear) 5a attached to the rotating shaft 2d of the commutator motor 2 and a second bevel gear 5b meshing with the first bevel gear 5a are housed. Thus, the rotational force of the rotating shaft 2 d of the commutator motor 2 is converted into a direction perpendicular to the rotating shaft direction of the commutator motor 2 and transmitted to the spindle 6. A grinder (grinding stone) 1 is attached to the spindle 6 as a tip tool, and grinding or cutting work becomes possible. A semicircular portion of the circular grinder 1 is covered with a protective cover 1a.

  FIG. 3 is a side sectional view of the resin molded armature 2a of the present invention, and FIG. 4 is an enlarged sectional view of a main part of the resin molded armature 2a of the present invention. A core (iron core) 2f is fixed to the rotating shaft 2d, and a coil (not shown) is wound around the axis X direction in a slot (not shown) of the core 2f, and the coil is one end of the core 2f. Coil end portion 2e1 protruding to the other end of the core 2f and coil end portions 2e2 and 2e3 protruding to the other end of the core 2f. The coil end portion 2e3 is electrically connected to the commutator 2h.

  According to the present invention, an elastic adhesive is applied to the inside of the mold resin coating layer 9 between the core 2f and the commutator 2h, and the adhesive layer 11 is formed in the vicinity of the coil end portion Y2. This coil end portion Y2 is a constricted portion 10 that is a minimum outer diameter portion (boundary portion between the coil end portions 2e2 and 2e3) of the winding diameter located between the coil end portions 2e2 and 2e3, and is depressed on the rotating shaft side. It has a shape. The coils in the slots of the core 2f and the coil end portions 2e1, 2e2, and 2e3 are covered with the mold resin coating layer 9, respectively.

  When an operator uses such a disc grinder 100, the drive power of the commutator motor 2 is turned on by the switch 7 provided in the switch handle portion 8 shown in FIG. 1, and the switch handle portion 8 and the gear cover portion 4 are turned on. The side handle portion 4b provided is gripped, and the grinder 1 is pressed against a workpiece (workpiece) (not shown) to perform an iron material grinding operation or a stone material cutting operation.

  For example, in the case of a stone cutting work, stone cutting waste is generated along with the work, which is sucked from the air intake window 8a provided in the switch handle portion 8, and this cutting waste is coiled in the resin mold armature 2a. It is sprayed on (including the coil end portions 2e1, 2e2 and 2e3) to damage the coil and cause damage such as wear or disconnection. On the other hand, according to the resin-molded armature 2a of the present invention, as shown in FIG. 3, the coil end portion 2e1 of the coil protruding at one end portion in the rotation axis direction of the core 2f, the other in the rotation axis direction of the core 2f. Since the coil end portions 2e2 and 2e3 of the coil protruding to the end portion are covered with the mold resin coating layer 9, the coil is prevented from being damaged by an intruder from the outside such as cutting waste or cutting waste. Moreover, even if a crack occurs in the mold resin coating layer 9, the coil is protected by the elastic adhesive layer 11, so that the crack does not occur in the coil. Therefore, it is possible to completely prevent the disconnection of the coil near Y2, which has been a problem in the past.

[Second Embodiment]
In FIG. 5, the principal part expanded sectional view of the resin mold armature which concerns on the 2nd Embodiment of this invention is shown. In the second embodiment, an elastic adhesive layer is formed on the inner side of the mold resin coating layer 9 between the core 2f and the commutator 2h in the first embodiment described above, and the commutator hook portion Y1 (the commutator 2h) It is provided from the vicinity of the coil connection portion) to the coil end Y2 (neck portion 10). The coils in the slots of the core 2f and the coil end portions 2e1, 2e2, and 2e3 are covered with the mold resin coating layer 9, respectively.

  During power tool operation, commutation may deteriorate due to excessive vibration of the commutator motor or deformation of the rotating shaft, and the commutator 2h and the coil connection may be heated to a high temperature. This heating may cause cracks in the resin mold in the vicinity of Y1 (the commutator-coil connection portion), and the coil may be disconnected. Therefore, in the second embodiment, not only the vicinity of Y2 of the coil end but also the coil in the adjacent portion Y1 (the connecting portion between the commutator 2h and the coil) of the coil end portion 2e3 with the commutator 2h is an elastic adhesive layer. Protect. This makes it possible to completely prevent the coil disconnection.

  In FIGS. 3 to 5, the constricted portion 10 is provided in the resin mold portion between the coil end portions 2e2 and 2e3. The shape of this portion is determined in consideration of mass productivity. It does not have to be.

  As mentioned above, the invention made by the present inventor has been specifically described on the basis of the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Is possible.

1 is a side cross-sectional view of a power tool using a commutator motor according to a first embodiment of the present invention. The upper surface sectional view of the electric tool which uses the commutator electric motor concerning a 1st embodiment of the present invention. The side sectional view of the resin mold armature concerning the 1st embodiment of the present invention. The principal part expanded sectional view of the resin mold armature concerning a 1st embodiment of the present invention. The principal part expanded sectional view of the resin mold armature which concerns on the 2nd Embodiment of this invention. Side surface sectional drawing of the conventional resin mold armature.

Explanation of symbols

1: Grinder
1a: protective cover 2: commutator motor
2a: Resin mold armature 2b: Stator 2c: Cooling fan 2d: Rotating shaft 2e1, 2e2, 2e3: Coil end part 2f: Core 2h: Commutator 3: Motor housing part 4: Gear cover part 4a: Exhaust wind window 4b : Side handle 5a: First bevel gear (pinion gear)
5b: second bevel gear 6: spindle 7: switch 8: switch handle portion 8a: intake air window 8b: power cord 9: mold resin coating layer 10: constricted portion 11: adhesive layer 100: electric tool (disc grinder)

Claims (3)

A rotation axis;
A coil wound along the axial direction of the rotating shaft in a slot of a core fixed to the rotating shaft;
A coil end portion made of the coil formed to protrude outside the slot in the axial direction of the rotation shaft;
A commutator fixed to the rotating shaft and electrically connected to the coil end portion ;
A mold resin layer covering the entire coil;
In the armature of the commutator motor in which a constricted portion that is depressed on the rotating shaft side is formed in the coil end portion,
An armature for a commutator motor , wherein an elastic adhesive layer is formed between a coil surface of the constricted portion and the mold resin layer . The armature of a commutator motor according to claim 1, wherein the adhesive layer is formed from a connection portion between the commutator and the coil to the constricted portion. A power tool comprising the armature of the commutator motor according to claim 1.

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