JP5408466B2 - Commutator motor and electric tool using the same - Google Patents

Description

  The present invention relates to a commutator motor in which a stator coil is sealed with a resin mold and an electric tool using the same, and in particular, cooling air flowing between an outer peripheral surface of a rotor core and an inner peripheral surface of a stator core. The present invention relates to a commutator motor and an electric tool using the same.

  In the commutator motor, as shown in FIG. 8, the motor coil generates heat based on the field current of the stator coil bundle 4f during operation (hereinafter referred to as the stator coil). On the other hand, with the operation of the motor, heat is also generated in the rotor coil 3b. For this reason, the electric tool that uses the commutator motor takes into consideration a design for suppressing the rotational output of the motor so that the stator coil 4f or the rotor coil 3b does not exceed the allowable temperature.

  Therefore, in the miniaturization of electric tool motors, in order to obtain a motor with high output and good workability, the coil winding slot size of the stator core is limited to the limit so as to reduce the amount of heat generated by the stator coil. Expanding and reducing the heat generation by increasing the conductor cross-sectional area of the coil installed in the slot as much as possible.

  In addition, as disclosed in Patent Document 1 below, by dividing the coil end portion of the stator coil wound around the stator core into a plurality of portions in the radial direction, the heat radiation area of the stator coil is increased. Techniques for cooling the stator are known.

JP 2001-292544 A

  However, as shown in FIG. 8, when the stator coil 4 f is enlarged, the cooling air passage 10 between the inner peripheral surface 4 h of the stator core 4 a and the outer peripheral surface 3 h of the rotor 3 is narrowed, and the rotor 3 is cooled. Is insufficient. For this reason, there existed a problem that the temperature rise of the rotor 3 was unavoidable.

  Moreover, the technique of dividing the coil end portion of the stator coil into a plurality of pieces in the radial direction as disclosed in Patent Document 1 has a problem that a complicated work process is required. Further, the coil end part splitting technique disclosed in Patent Document 1 has a problem in that the coil end part of the stator coil is increased in the radial direction, resulting in a large motor housing or electric tool housing. Furthermore, when the motor housing or the like is made of a metal material, there has been a problem in terms of safety of electrical appliances in that the electrical insulation performance is lowered because the distance between the coil end portion of the stator coil and the housing portion approaches.

  Accordingly, an object of the present invention is to provide a commutator motor having a cooling air passage for solving the above-mentioned drawbacks of the prior art and improving the cooling effect of the stator and the rotor, and an electric tool using the same. is there.

  In order to solve the above problems, typical features of the invention disclosed in accordance with the present invention will be described as follows.

  According to one aspect of the present invention, the apparatus includes a rotor housed in the housing and extending in the direction of the rotation axis, and a stator disposed in the vicinity of the outer peripheral surface of the rotor and extending in the direction of the rotation axis. In the commutator motor, the rotor includes a rotor core having a circular outer peripheral surface portion in a rotational radial direction, and the stator includes a yoke core portion having a circular inner peripheral surface portion and an inner periphery of the yoke core portion. A stator core having a pair of magnetic pole core portions projecting from the facing portion of the rotor portion to the outer peripheral surface portion of the rotor core, and winding around the magnetic pole core portion in a slot formed by the magnetic pole core portion and the yoke core portion. And a stator coil having a coil end portion that protrudes in a bundle from both ends of the stator core in the rotation axis direction, and the stator coil is a thermosetting resin. The resin mold body of the stator coil is a resin mold that faces a cooling air passage between the outer peripheral surface portion of the rotor core and the inner peripheral surface of the yoke core portion. It is comprised so that it may have a level | step-difference part in a body surface part.

  According to another aspect of the present invention, the conductor portion of the stator coil wound in the slot is covered with an insulating sheet member, and the other conductor portion of the stator coil facing the cooling air path is It is comprised so that it may be exposed from the said insulating sheet member.

  According to still another aspect of the present invention, the maximum radial width (D19) in the other conductor portion of the stator coil exposed from the insulating sheet member is the insulating sheet wound in the slot. The stator coil is configured to be smaller than the maximum radial width (D18) of the conductor portion of the stator coil shielded from the cooling air by the member.

  According to still another feature of the present invention, the vertical distance (D13) connecting the apex of the stepped portion of the resin mold body surface portion from the radial center line of the rotor core is the distance of the rotor core. It is set to be larger than a vertical distance (D15) connecting the end portion of the magnetic pole core portion of the stator core from the radial center line.

  According to still another feature of the present invention, a radial distance between the step portion of the resin mold body surface portion and the outer peripheral surface portion of the rotor core is 2 mm or more.

  According to still another aspect of the present invention, the stator core is composed of a plurality of divided cores.

  According to still another aspect of the present invention, the housing is made of a metal material.

  According to still another aspect of the present invention, a housing, an electric motor housed in the housing, a tip tool for machining a workpiece to be mounted on one end of the housing, and in the housing And a power transmission mechanism unit that is housed and drives the tip tool by the power of the electric motor. The electric motor is constituted by a commutator motor having the above characteristics.

  According to the above feature of the present invention, the stator coil is configured by a resin mold body molded by a thermosetting resin, and the resin mold body of the stator coil includes the outer peripheral surface portion of the rotor core and the stator core. Since the resin mold body surface portion facing the cooling air passage between the peripheral surface and the peripheral surface is configured to have a stepped portion (concave portion), the cooling air passages of the stator coil and the rotor coil are expanded, and the cooling effect is improved. An excellent commutator motor and electric tool can be provided.

  According to another aspect of the present invention, the conductor portion of the stator coil wound in the slot is covered with an insulating sheet member, and the other conductor portion of the stator coil facing the cooling air path is a stepped portion. Since the electrical insulation is maintained by this, it can be configured to be exposed from the insulating sheet member. Thereby, it is possible to provide a commutator motor and a power tool that have high output and excellent electrical insulation.

  The above and other objects, and the above and other features and advantages of the present invention will become more apparent from the following description of the present specification and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 7. 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.

[About the configuration of the power tool]
FIG. 1 is a configuration diagram (cross-sectional view) of an entire power tool in which a commutator motor 30 according to an embodiment of the present invention is applied to a disc grinder 1. The disc grinder 1 includes a motor housing portion 2 that houses a commutator motor 30 according to the present invention, a gear cover portion 7 that is configured on a rotating shaft 3d of the motor of the motor housing portion 2, and a switch and a switch circuit of the commutator motor 30 ( A tail cover 6 for storing a power cable 6a.

  The commutator motor 30 housed in the motor housing portion 2 includes a rotor (armature) 3 fixed to the rotating shaft 3d and a stator 4 fixed to the motor housing portion, and on the output side of the rotating shaft 3d. When the cooling fan 5 is fixed and the cooling fan 5 rotates, the outside air for cooling (cooling air) is taken in from the air inlet 2a formed in the tail cover portion 6, and the cooling air is supplied to the motor housing portion 2, The air passes through the cooling air passage between the rotor 3 and the stator 4, and is discharged to the outside of the gear cover portion 7 through the fan air discharge port 2 b provided in the gear cover portion 7.

  The gear cover portion 7 includes a first bevel gear (pinion gear) 3e connected to the rotating shaft 3d of the commutator motor 30 and a second bevel gear 3f that meshes with the first bevel gear 3e. The power transmission mechanism is housed, and the rotational speed and rotational force of the commutator motor 30 are converted into a direction perpendicular to the axial direction of the rotating shaft 3d of the commutator motor 30 and transmitted to the spindle 3g. A grinding wheel (grinder) 8 is attached to the spindle 3g as a tip tool, and grinding or cutting work becomes possible. The semicircular portion of the circular grindstone 8 is covered with a protective cover 8a.

[Configuration of commutator motor]
FIG. 2 is a cross-sectional view of commutator motor 30 along the line AA in FIG. The stator 4 includes, for example, a stator core 4a having an axial length of 45 to 60 mm and an outer diameter of 50 mm. The stator core 4a has a pair of opposing magnetic pole core portions (N pole and S pole) 4c and a pair of curved yoke core portions 4b connected to the pair of magnetic pole portions 4c, and has an overall cross-sectional outer shape. Has a substantially circular shape.

  Two sets of slots S1 and S2 are formed with respect to the magnetic pole core portion 4c by the adjacent magnetic pole core portion 4c and the yoke core portion 4b. In each of the slots S1 and S2, a stator coil bundle 4f (hereinafter, “stator coil bundle” is simply referred to as “stator coil”) is installed. A separation distance D11 between adjacent stator coils 4f is set to about 6 mm at maximum, and a stator conductor 4f is configured by winding a conductor as thick as possible around the magnetic pole part 4c so as to reduce the specific resistance. Due to the use of a thick conductor, heat generation from the stator coil 4f is also reduced. An insulating sheet 9 made of an electrically insulating material is installed on the stator core 4a that is in close contact with the stator coil 4f, and a basic insulation treatment is applied between the stator core 4a and the stator coil 4f.

  As will be described later, a thermosetting resin is molded on the stator coil 4f in order to improve the coil fixing and the heat dissipation effect of the coil. As shown in FIG. 2, the resin mold body of the stator coil 4f (hereinafter, the stator coil 4f may be referred to as the resin mold body 4f) is covered (blocked) with the insulating sheet 9 in the slots S1 and S2. The stator coil 4f has a coating portion maximum width (thickness) D18 in the radial direction. Further, the exposed portion maximum width (thickness) D19 in the radial direction of the resin mold body 4f exposed from the insulating sheet 9 is defined as a dimension (D19 <D18) shorter than the covering portion maximum width D18, and the resin mold body 4f A stepped portion (concave portion) 13 is formed. The stepped portion 13 is formed between the rotor 3 and the stator 4 and extends the cross-sectional area of the cooling air passage 10 extending in the direction of the rotation axis, and the conductor of the stator coil 4f is passed through the insulating sheet 9. Instead, the coil cooling effect is improved by direct exposure to cooling air.

  As shown in FIG. 2, the step portion apex 13a of the step portion 13 provided in the stator coil 4f is vertical from the horizontal center line 14 in the rotational radial direction of the motor cross section to the tip portion 4d of the magnetic pole core portion 4c. It is located at a distance D13 (D13> D15) higher than the distance D15. As shown in the modification of FIG. 7, the step portion apex 13a may have a height D13 ((D13 = D15)) substantially equal to the vertical distance D15.

  With the configuration of the commutator motor 30, the coil bundle 4 f as thick as possible is installed in the area within the slots S 1 and S 2 beyond the vertical distance D 15 that cannot be the cooling air path 10 of the rotor 3. By providing the step portion 13 in a region lower than the vertical distance D15 that becomes the cooling air passage 10, the coil bundle 4f that is as thin as possible can be installed. Therefore, it is possible to enlarge the cooling air passage 10 formed between the inner peripheral surface 4h of the stator 4 and the outer peripheral surface 3h of the rotor 3 by the step portion 13 as compared with the prior art. 3 can be improved, and the stator coil 4f can be enlarged to improve the cooling effect of the stator 4.

  Moreover, since the coil radial direction maximum width D19 in the stepped portion 13 is reduced, the spatial distance D16 between the rotor core 3a and the conductor 4f1 exposed from the coil resin molded body 4f can be defined to be 2 mm or more. Furthermore, the spatial distance D17 between the stator core 4a and the conductor 4f2 exposed from the coil 4f can be defined to be 2 mm or more. That is, the rotor core 3a and the stator core 4a can satisfy the basic insulation requirements according to the Electrical Appliance and Material Safety Law specified by the Ministerial Ordinance with respect to the conductors 4f1 and 4f2. For this reason, even if the motor housing portion 2 (see FIG. 1) that houses and supports the stator core 4a and the rotor core 3a is made of a metal material having high breaking strength, sufficient electrical insulation from the electric circuit is achieved. Therefore, it is possible to provide a power tool that is safe for the operator.

  In the above embodiment, in particular, the step portion apex 13a of the step portion 13 provided in the stator coil 4f is a vertical distance from the horizontal center line 14 in the rotational radial direction of the motor cross section to the tip portion 4d of the magnetic pole core portion 4c. It is located at a distance D13 (D13> D15) higher than D15, and the stepped portion 13 makes it easier for the cooling air to pass through the coil 4f located in the back of the slot S1 or S2. Further, the insulating sheet 9 covers a limited range from the divided portion 4e of the stator core 4a to the vicinity of the magnetic pole end portion 4d of the magnetic pole core portion 4a. For this reason, since about half of the resin mold body surface part of the stator coil 4f faces the cooling air passage 10, the rotor 3 and the stator coil 4f are compared with the modification shown in FIG. The cooling effect can be dramatically improved.

  In the modification shown in FIG. 7, the step portion apex 13a has a height D13 ((() substantially equal to the vertical distance D15 from the horizontal center line 14 to the tip end portion 4d of the magnetic pole core portion 4c in the rotational radial direction of the motor cross section). D13 = D15), the cross-sectional shape of the stepped portion 13 is a substantially right-angled shape, which makes it easy to manufacture the resin molded body of the stator coil 4f.

[Assembly procedure for commutator motor]
Next, an assembly procedure of the commutator motor 30 according to the embodiment shown in FIG. 2 will be described with reference to FIGS.

  (1) As shown in FIG. 3, in order to constitute one of the divided stators 22a (see FIG. 6), a stator coil (coil bundle) 4f is installed in the stator core 4a.

  (2) Next, as shown in FIG. 4, the stator core 4a and the stator coil 4f are sandwiched in the cavity 20a by the lower mold 20 and the upper mold 21 having the cavity 20a formed with predetermined dimensions. By pressing the stator coil bundle 4f, the outer shape of the stator coil bundle 4f is formed into a predetermined dimension.

  (3) Subsequently, a thermosetting resin is injected into a cavity 20a formed by the lower mold 20 and the upper mold 21 (see FIG. 4) via a runner (not shown), and the stator coil 4f is molded to form a resin mold body 22 (see FIG. 6) of the stator 4 in which the stator coil 4f is fixed to the stator core 4a. At this time, as shown in FIG. 5, the coil end portion 4 g protruding in a bundle from both ends in the rotation axis direction of the stator core 4 a is also a cavity formed by the lower die 20 and the upper die 21. It is installed in 20a and resin molded.

  After the thermosetting resin injected into the cavities of the molds 20 and 21 is cured, the molds 20 and 21 are opened to obtain a pair of split stators 22a and 22b as shown in FIG. By resin molding using the molds 20 and 21, a resin mold portion 12 is formed in the gap between the conductors 4f.

  (4) Next, the pair of split stators 22a and 22b are joined together to assemble the stator 4.

  According to the above assembly procedure, since the stator core 4a is a split core, a larger stator coil bundle 4f can be installed. Further, since the stator coil 4f can be sandwiched from above and below by the lower mold 20 and the upper mold 21, it is easy to form the stator coil bundle 4f, and disconnection accidents during molding can be prevented. Furthermore, the molds 20 and 21 can be easily removed after sealing with the resin mold.

  When the commutator motor 30 according to the above embodiment is assembled in the motor housing portion 2 as shown in FIG. 1 to assemble the disc grinder, the air sucked from the air inlet 2a by the cooling fan 5 is converted into the commutator. The cooling air passage 10 (see FIG. 2) of the motor 30 can be circulated to efficiently dissipate heat generated by the rotor 3 and the stator 4 of the commutator motor 30. Thereby, it is possible to provide a power tool with high output and excellent electrical insulation.

  As mentioned above, although the invention made | formed by this inventor was demonstrated based on embodiment, this invention is not limited to the said embodiment, A various change is possible within the range which does not deviate from the summary.

Sectional drawing which shows the disc grinder which uses the commutator motor which concerns on embodiment of this invention. Sectional drawing which follows the AA line of the commutator motor shown in FIG. Sectional drawing of the stator which comprises the commutator motor shown in FIG. Sectional drawing of the metal mold | die for forming the stator shown in FIG. 3 in a resin mold body. The top view which follows the BB line of the stator shown in FIG. Sectional drawing of a pair of division | segmentation stator by which resin molding was carried out. Sectional drawing which shows the modification of the commutator motor which concerns on embodiment of this invention. Sectional drawing of the commutator motor which concerns on a prior art.

Explanation of symbols

1: Disc grinder (electric tool) 2: Motor housing portion 2a: Air inlet 2b: Fan air outlet 3: Rotor 3a: Rotor core 3b: Rotor coil 3c: Commutator 3d: Rotating shaft 3e: First Bevel gear 3f: second bevel gear 3g: spindle 3h: outer peripheral surface of rotor 4: stator 4a: stator core 4b: stator yoke 4c: magnetic pole core portion 4d: magnetic pole core end 4e: divided portion 4f : Stator coil (coil bundle)
4f1, 4f2: Conductor 4g: Coil end part 4h: Stator core inner peripheral surface 5: Cooling fan 6: Tail cover part 6a: Power cable 7: Gear cover part 8: Grinding wheel 8a: Protection cover 9: Insulating sheet 10: Cooling air passage 11: Clearance 12: Resin mold part 13: Step part 13a of resin mold body 13a: Step part apex 14: Center line 20: Lower mold 21: Upper mold 22a, 22b: Split stator 30, 40: Rectification Child motor D15: Height of magnetic pole core end (distance)
D16: Distance between stator coil and rotor core D17: Distance between stator coil and magnetic pole core D18: Width in stator coil slot D19: Width of stepped portion of stator coil S1, S2: Stator slot

Claims (8)

In a commutator motor having a rotor and a stator housed in a housing,
  The rotor includes a rotor core having a circular outer peripheral surface portion in a radial direction orthogonal to the rotation axis,
  The stator is wound around the magnetic pole core portion, a stator core having a yoke core portion having a circular inner peripheral surface portion, a magnetic pole core portion protruding from the yoke core portion toward the rotor core, and thermosetting. A stator coil molded with a conductive resin,
  A resin mold body of the stator coil is formed to extend along the inner peripheral surface of the yoke core part, and a first coil part close to the magnetic pole core part and a second coil part spaced apart from the magnetic pole core part And more
  The dimension in the radial direction of the stator coil in the cross section orthogonal to the rotation axis is set so that the dimension of the second coil part is smaller than that of the first coil part, and the inner peripheral surface of the yoke core part and the rotor core A commutator motor characterized by extending a cooling air passage between the outer peripheral surface of the motor. A stator coil wound in a slot formed by the magnetic pole core part and the yoke core part is covered with an insulating sheet member, and the other stator coil facing the cooling air path is formed from the insulating sheet member. The commutator motor according to claim 1, wherein the commutator motor is exposed. The resin coil body of the stator coil exposed from the insulating sheet member has a maximum radial width (D19) orthogonal to the rotation axis of the resin mold body of the stator coil wound in the slot. The commutator motor according to claim 2, wherein the commutator motor is smaller than a maximum radial width (D18). A step portion is formed between the first coil portion and the second coil portion, and a vertical line extending from a horizontal line connecting the center of the rotating shaft and an intermediate point of the adjacent resin mold body to the corner portion of the step portion. The distance (D13) in the direction is set to be larger than the distance (D15) from the horizontal line to the end of the magnetic pole core part, according to any one of claims 1 to 3. Commutator motor. The radial distance (D16) between the surface of the second coil portion and the outer peripheral surface of the rotor core is 2 mm or more, and any one of claims 1 to 4 Commutator motor described in one. The stator core is a commutator motor as claimed in any one of claims 1 to 5, characterized in that it is composed of a plurality of divided cores.   The commutator motor according to any one of claims 1 to 6, wherein the housing is made of a metal material. A housing; an electric motor housed in the housing; a tip tool for machining a workpiece mounted on one end of the housing; and the tip of the tip housed in the housing by the power of the electric motor A power transmission mechanism for driving the tool,
The electric tool is constituted by the commutator motor according to any one of claims 1 to 7.

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