Electric tool

Abstract

To suppress service lives of a commutator and a carbon brush from shortening.SOLUTION: An electric tool comprises: a motor that has a rotor including a rotor shaft fixed with a fan and a commutator, a stator arranged around the rotor, and a carbon brush which is in contact with the commutator, in which the rotor rotates only in one direction with a motor rotary shaft extending in a predetermined direction as a center; a housing having a tube part arranged around the motor, a bottom part connected to the tube part and a ventilator window provided at the bottom part, which supports the stator; and a rib part protruding from the bottom part. When a numerical aperture of the ventilation window in a first section in an annular range from a 0° position to a 90°position toward a reverse rotation direction of the rotor is defined as P1 and a numerical aperture of the ventilation window in a second section in the annular range from the 0° position to the 90° position toward a positive rotation direction of the rotor is defined as P2, a condition of P1<P2 is satisfied. An end part at one side of the rib part is arranged closer to the one side than the carbon brush.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The technology disclosed in this specification relates to power tools. [Background technology]

[0002] 2. Description of the Related Art In the technical field related to power tools, a grinder such as that disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-112974 A Summary of the Invention [Problem to be solved by the invention]

[0004] The grinder grinds the object to be ground. When the object is ground with the grinder, a large amount of dust is generated. The dust may be carried by the cooling air and transported between the commutator and the carbon brushes of the motor. If the dust gets between the commutator and the carbon brushes, the life of the commutator and the carbon brushes may be reduced.

[0005] The technology disclosed in this specification aims to suppress the decrease in the life span of the commutator and the carbon brush. [Means for solving the problem]

[0006] This specification discloses a power tool. The power tool includes a rotor including a fan and a rotor shaft to which a commutator is fixed, a stator disposed around the rotor, and a carbon brush that contacts the commutator, and is a motor in which the rotor rotates only in one direction about a motor rotation axis extending in a predetermined direction, a cylindrical portion disposed around the motor, a bottom portion connected to the cylindrical portion, and a ventilation window provided in the bottom portion, and may include a housing that supports the stator and a rib portion protruding from the bottom portion. The fan may be fixed to a first portion of the rotor shaft on one side of the center of the rotor shaft in a predetermined direction. The commutator may be fixed to a second portion of the rotor shaft on the other side of the center of the rotor shaft in a predetermined direction. The bottom portion may be disposed on the other side of the commutator. The rib portion may protrude from the bottom portion to one side. On a predetermined plane orthogonal to the motor rotation axis, a first reference circle having a diameter that is 1 times the outer diameter of the commutator and centered on the motor rotation axis, and on the predetermined plane, a second reference circle having a diameter that is 1.5 times the outer diameter of the commutator and centered on the motor rotation axis, and an annular range between the first reference circle and the second reference circle may be defined. On the predetermined plane, taking the position where a reference line passing through the center of the motor rotation axis and the carbon brush intersects the second reference circle as the 0° position, and the opening ratio of the ventilation window in the first section of the annular range from the 0° position to the 90° position in the reverse rotation direction of the rotor as P1, and the opening ratio of the ventilation window in the second section of the annular range from the 0° position to the 90° position in the forward rotation direction of the rotor as P2, the condition P1 < P2 may be satisfied. One end of the rib portion on one side may be disposed on one side of the carbon brush.

Advantages of the Invention

[0007] According to the technology disclosed in this specification, a decrease in the service life of the commutator and the carbon brush is suppressed.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a perspective view from the front showing a grinder according to the first embodiment. [Diagram 2] FIG. 2 is a perspective view from the rear showing a grinder according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing the grinder according to the first embodiment. [Figure 4] FIG. 4 is an exploded perspective view showing the grinder according to the first embodiment, as viewed from the rear side. [Diagram 5] FIG. 5 is an exploded perspective view showing a part of the grinder according to the first embodiment, as seen from the rear side. [Figure 6] FIG. 6 is a view of the motor housing according to the first embodiment as viewed from the rear side. [Figure 7] FIG. 7 is a view of the motor housing according to the first embodiment as viewed from the rear side. [Figure 8] FIG. 8 is a cross-sectional view showing a part of the grinder according to the first embodiment. [Figure 9] FIG. 9 is a view of the motor housing according to the first embodiment as viewed from the front side. [Figure 10] FIG. 10 is a perspective cross-sectional view showing a part of the grinder according to the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a part of the grinder according to the first embodiment. [Figure 12] FIG. 12 is a schematic view of the motor housing according to the first embodiment, as viewed from the rear side. [Figure 13] FIG. 13 is a perspective cross-sectional view showing a part of the grinder according to the second embodiment. [Figure 14] FIG. 14 is a perspective view showing a rib member according to the second embodiment. [Figure 15] FIG. 15 is a perspective cross-sectional view showing a part of the grinder according to the third embodiment. [Figure 16] FIG. 16 is a perspective view showing an insulator according to the third embodiment. [Figure 17] FIG. 17 is a perspective cross-sectional view showing a part of a grinder according to the fourth embodiment. [Figure 18] FIG. 18 is a perspective view showing an inner baffle according to the fourth embodiment. [Figure 19]FIG. 19 is a perspective cross-sectional view showing a part of a grinder according to a fifth embodiment. [Figure 20] FIG. 20 is a perspective view showing an insulator according to the fifth embodiment. [Figure 21] FIG. 21 is a perspective cross-sectional view showing a part of the grinder according to the sixth embodiment. [Figure 22] FIG. 22 is a perspective view showing an inner baffle according to the sixth embodiment. [Figure 23] FIG. 23 is a cross-sectional view showing a part of the grinder according to the sixth embodiment. [Figure 24] FIG. 24 is a perspective view showing a cutter according to the seventh embodiment. [Diagram 25] FIG. 25 is a perspective view showing a cutter according to the seventh embodiment. [Figure 26] FIG. 26 is a perspective view showing a motor housing 4 according to the seventh preferred embodiment. [Figure 27] FIG. 27 is a perspective cross-sectional view showing a part of a cutter according to the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one or more embodiments, the power tool includes a rotor including a fan and a rotor shaft to which a commutator is fixed, a stator disposed around the rotor, and a carbon brush that contacts the commutator, and is a motor in which the rotor rotates only in one direction about a motor rotation axis extending in a predetermined direction, a cylindrical portion disposed around the motor, a bottom portion connected to the cylindrical portion, and a ventilation window provided in the bottom portion, and may include a housing that supports the stator and a rib portion protruding from the bottom portion. The fan may be fixed to a first portion of the rotor shaft on one side of the center of the rotor shaft in a predetermined direction. The commutator may be fixed to a second portion of the rotor shaft on the other side of the center of the rotor shaft in a predetermined direction. The bottom portion may be disposed on the other side of the commutator. The rib portion may protrude from the bottom portion to one side. On a predetermined plane orthogonal to the motor rotation axis, a first reference circle having a diameter that is 1 times the outer diameter of the commutator and centered on the motor rotation axis, a second reference circle having a diameter that is 1.5 times the outer diameter of the commutator on the predetermined plane and centered on the motor rotation axis, and an annular range between the first reference circle and the second reference circle may be defined. On the predetermined plane, a position where a reference line passing through the center of the motor rotation axis and the carbon brush intersects the second reference circle is defined as the 0° position, and when the opening ratio of the ventilation window in the first section of the annular range from the 0° position to the 90° position in the reverse rotation direction of the rotor is P1 and the opening ratio of the ventilation window in the second section of the annular range from the 0° position to the 90° position in the forward rotation direction of the rotor is P2, the condition P1 < P2 may be satisfied. One end of the rib portion on one side may be disposed on one side of the carbon brush.

[0010] In the above configuration, the intrusion of dust between the commutator and the carbon brush is suppressed. Therefore, the reduction in the service life of the commutator and the carbon brush is suppressed.

[0011] In one or more embodiments, the rib portion may be disposed at least partially around the commutator.

[0012] In the above configuration, the intrusion of dust between the commutator and the carbon brush is suppressed.

[0013] In one or more embodiments, the other end of the rib may be connected to one surface of the base.

[0014] In the above configuration, the position of the rib portion is stabilized.

[0015] In one or more embodiments, the ribs may be integral with the base.

[0016] With the above configuration, the number of parts of the power tool is reduced.

[0017] In one or more embodiments, the ribs may be separate from the base.

[0018] In the above configuration, the rib portion can be easily processed into any desired shape.

[0019] In one or more embodiments, the stator may include a stator core, an insulator fixed to the stator core, and a coil supported by the insulator. One end of the rib portion may face the insulator.

[0020] The above configuration prevents dust from entering between the commutator and the carbon brushes.

[0021] In one or more embodiments, one end of the rib may be disposed around at least a portion of the circumference of the coil.

[0022] The above configuration prevents dust from entering between the commutator and the carbon brushes.

[0023] In one or more embodiments, the power tool may include a bearing that supports the other end of the rotor shaft. The bottom portion may have a bearing holder that holds the bearing.

[0024] In the above configuration, the rotor shaft is supported at the bottom via a bearing.

[0025] In one or more embodiments, the power tool may include a brush holder for holding a carbon brush. The rib portion may have a recess in which the brush holder is disposed.

[0026] In the above configuration, interference between the brush holder and the rib portion is suppressed.

[0027] In one or more embodiments, the electric power tool may include a rotor including a rotor shaft to which a fan and a commutator are fixed, a stator including a stator core, an insulator fixed to the stator core, and a coil supported by the insulator and disposed around the rotor, and a carbon brush in contact with the commutator, the motor rotating around a motor rotation axis extending in a predetermined direction, a housing supporting the stator, the housing having a cylindrical portion disposed around the motor, a bottom portion connected to the cylindrical portion, and an air window provided in the bottom portion, and a rib portion protruding from the insulator. The fan may be fixed to a first portion of the rotor shaft on one side of a center of the rotor shaft in the predetermined direction. The commutator may be fixed to a second portion of the rotor shaft on the other side of the center of the rotor shaft in the predetermined direction. The bottom portion may be disposed on the other side of the commutator. The rib portion may protrude from the insulator to the other side. An end portion on the other side of the rib portion may be disposed on the other side of an end portion on one side of the carbon brush.

[0028] With the above-described configuration, dust is prevented from entering between the commutator and the carbon brushes, and therefore a decrease in the lives of the commutator and the carbon brushes is suppressed.

[0029] In one or more embodiments, the other end of the rib may be disposed around at least a portion of the circumference of the commutator.

[0030] The above configuration prevents dust from entering between the commutator and the carbon brushes.

[0031] In one or more embodiments, one end of the rib may be connected to the insulator.

[0032] In the above configuration, the position of the rib portion is stabilized.

[0033] In one or more embodiments, the ribs may be integral with the insulator.

[0034] With the above configuration, the number of parts of the power tool is reduced.

[0035] In one or more embodiments, the other end of the rib may face one surface of the bottom portion.

[0036] The above configuration prevents dust from entering between the commutator and the carbon brushes.

[0037] In one or more embodiments, the power tool may include a bearing that supports the other end of the rotor shaft. The bottom portion may have a bearing holder that holds the bearing.

[0038] In the above configuration, the rotor shaft is supported at the bottom via a bearing.

[0039] In one or more embodiments, the power tool may include a screw for fastening the stator core and the insulator.

[0040] In the above configuration, the stator core and the insulator are fixed together by screws.

[0041] In one or more embodiments, the electric power tool may include a rotor including a rotor shaft to which a fan and a commutator are fixed, a motor including a stator including a stator core, an insulator fixed to the stator core, and a coil supported by the insulator and disposed around the rotor, and a carbon brush in contact with the commutator, the rotor rotating around a motor rotation axis extending in a predetermined direction, a housing including a cylindrical portion disposed around the motor, a bottom portion connected to the cylindrical portion, and an air window provided in the bottom portion, the housing supporting the stator, a brush holder supported by the cylindrical portion and holding the carbon brush, and an inner baffle disposed between the insulator and the brush holder in the predetermined direction. The fan may be fixed to a first portion of the rotor shaft on one side of a center of the rotor shaft in the predetermined direction. The commutator may be fixed to a second portion of the rotor shaft on the other side of the center of the rotor shaft in the predetermined direction. The bottom portion may be disposed on the other side of the commutator. A first reference circle having a diameter 1 times the outer diameter of the commutator and centered on the motor rotation shaft may be defined in a predetermined plane perpendicular to the motor rotation shaft, a second reference circle having a diameter 1.5 times the outer diameter of the commutator and centered on the motor rotation shaft in the predetermined plane, and an annular range between the first reference circle and the second reference circle may be defined. In the predetermined plane, a position where a reference line passing through the center of the motor rotation shaft and the carbon brush intersects with the second reference circle is defined as a 0° position, and an area of ​​the inner baffle in a first section of the annular range from the 0° position to a 90° position in the counter-rotation direction of the rotor is defined as S1, and an area of ​​the inner baffle in a second section of the annular range from the 0° position to a 90° position in the forward rotation direction of the rotor is defined as S2, whereby a condition of S1>S2 may be satisfied. In the radial direction of the motor rotation shaft, an inner end of the inner baffle may be disposed inside an inner end of the insulator.

[0042] With the above-described configuration, dust is prevented from entering between the commutator and the carbon brushes, and therefore a decrease in the lives of the commutator and the carbon brushes is suppressed.

[0043] In one or more embodiments, the inner baffle may be separate from the housing.

[0044] In the above-described configuration, the inner baffle can be easily processed into any desired shape.

[0045] In one or more embodiments, the power tool may include a screw for fastening the stator core and the insulator. The inner baffle may be fastened to the insulator by the screw.

[0046] In the above configuration, the stator core, the insulator, and the inner baffle are fixed together by screws.

[0047] In one or more embodiments, the inner baffle may be integral with the housing.

[0048] With the above configuration, the number of parts of the power tool is reduced.

[0049] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiment. The components of the embodiments described below can be appropriately combined. In addition, some components may not be used.

[0050] In the embodiment, the positional relationship of each part will be described using the terms "left", "right", "front", "rear", "upper", and "lower". These terms indicate relative positions or directions based on the center of the power tool.

[0051] The electric power tool has a motor. A direction parallel to the motor rotation shaft AX, which is the rotation shaft of the motor, is appropriately referred to as the axial direction, a direction going around the motor rotation shaft AX is appropriately referred to as the circumferential direction or rotation direction, and a radial direction of the motor rotation shaft AX is appropriately referred to as the radial direction. In addition, in the radial direction, a position close to or approaching the motor rotation shaft AX is appropriately referred to as the radially inner side or inner circumferential side, and a position far from or away from the motor rotation shaft AX is appropriately referred to as the radially outer side or outer circumferential side. In the embodiment, the motor rotation shaft AX extends in the front-rear direction. One axial side is the front side, and the other axial side is the rear side.

[0052] [First embodiment] A first embodiment will be described. In this embodiment, a power tool 1A is a disc grinder for grinding an object to be ground. In this embodiment, the power tool 1A will be referred to as a grinder 1A as appropriate.

[0053] Fig. 1 is a perspective view of the grinder 1A according to the present embodiment, seen from the front side. Fig. 2 is a perspective view of the grinder 1A according to the present embodiment, seen from the rear side. Fig. 3 is a cross-sectional view of the grinder 1A according to the present embodiment. Fig. 4 is an exploded perspective view of the grinder 1A according to the present embodiment, seen from the rear side.

[0054] The grinder 1A includes a housing 2, a motor 16, and a spindle 6.

[0055] The housing 2 has a gear housing 3 , a motor housing 4 arranged on the rear side of the gear housing 3 , and a handle housing 5 arranged on the rear side of the motor housing 4 .

[0056] The gear housing 3 accommodates a spindle 6. The spindle 6 rotates about an output rotation axis BX that extends in the vertical direction. A retainer 8 is fixed to the lower part of the gear housing 3. An upper part of the spindle 6 is rotatably supported by a bearing 7. A lower part of the spindle 6 is rotatably supported by a bearing 9. The bearing 7 is held by the gear housing 3. The bearing 9 is held by the retainer 8.

[0057] A bevel gear 10 is provided on the upper part of the spindle 6. The lower end of the spindle 6 protrudes downward from the retainer 8. A disc-shaped grinding wheel 13 is attached to the lower end of the spindle 6 by an inner flange 11 and an outer flange 12. A wheel cover 14 is fixed to the retainer 8. The wheel cover 14 covers the rear part of the disc-shaped grinding wheel 13. A plurality of exhaust ports 15 are formed in the front part of the gear housing 3.

[0058] The motor housing 4 accommodates the motor 16. The motor housing 4 has a cylindrical portion 41 arranged around the motor 16, a bottom portion 42 connected to the rear end portion of the cylindrical portion 41, and a plurality of air windows 43 provided in the bottom portion 42. The bottom portion 42 is arranged so as to cover the opening at the rear end portion of the cylindrical portion 41.

[0059] FIG. 5 is an exploded perspective view from the rear side showing a part of the grinder 1A according to this embodiment. FIGS. 6 and 7 are views of the motor housing 4 according to this embodiment as viewed from the rear side. In FIG. 7, the motor housing 4 is shown by a virtual line. FIG. 8 is a cross-sectional view showing a part of the grinder 1A according to this embodiment. FIG. 8 corresponds to the cross-sectional view taken along the line AA in FIG. 4. FIG. 9 is a view of the motor housing 4 according to this embodiment as viewed from the front side. FIG. 10 is a cross-sectional perspective view showing a part of the grinder 1A according to this embodiment. FIG. 11 is a cross-sectional view showing a part of the grinder 1A according to this embodiment. FIG. 11 corresponds to the cross-sectional view taken along the line BB in FIG. 6.

[0060] The motor 16 has a stator 17, a rotor 18, and carbon brushes 26. The stator 17 is supported by a cylindrical portion 41 of the motor housing 4. The stator 17 is disposed around the rotor 18. The motor 16 is an inner rotor type. The rotor 18 rotates about a motor rotation axis AX that extends in the front-rear direction.

[0061] The stator 17 includes a stator core 171 , an insulator 172 fixed to the stator core 171 , and a coil 173 supported by the insulator 172 .

[0062] The stator core 171 and the insulator 172 are fixed together by screws 60. At least a portion of the insulator 172 is disposed forward of the stator core 171. At least a portion of the insulator 172 is disposed rearward of the stator core 171. The coil 173 is wound around the stator core 171 with the insulator 172 interposed therebetween.

[0063] The rotor 18 has a rotor core 181, a coil 182 supported by the rotor core 181, a rotor shaft 19 fixed to the rotor core 181, a fan 23 fixed to the rotor shaft 19, and a commutator 25 fixed to the rotor shaft 19.

[0064] A front portion of the rotor shaft 19 protrudes forward from the rotor core 181 and the coils 182. A rear portion of the rotor shaft 19 protrudes rearward from the rotor core 181 and the coils 182.

[0065] The fan 23 is fixed to a front portion (first portion) of the rotor shaft 19, which is forward of the center of the rotor shaft 19 in the front-rear direction. The fan 23 is disposed forward of the rotor core 181 and the coils 182.

[0066] The commutator 25 is fixed to a rear portion (second portion) of the rotor shaft 19 rearward of the center of the rotor shaft 19 in the front-to-rear direction. The commutator 25 is disposed rearward of the rotor core 181 and the coils 182. The bottom portion 42 is disposed rearward of the commutator 25. The commutator 25 is made up of a plurality of commutator segments.

[0067] The front end of the rotor shaft 19 passes through a partition plate 20 provided between the motor housing 4 and the gear housing 3. A bevel gear 22 is provided at the front end of the rotor shaft 19. The bevel gear 22 meshes with the bevel gear 10 of the spindle 6 inside the gear housing 3.

[0068] A front portion of the rotor shaft 19 is rotatably supported by a bearing 21. A rear portion of the rotor shaft 19 is rotatably supported by a bearing 29. The bearing 21 is held by the gear housing 3. The bearing 29 is held by a bottom portion 42. The bottom portion 42 has a bearing holding portion 44 that holds the bearing 29.

[0069] The carbon brushes 26 come into contact with the commutator 25. The carbon brushes 26 are arranged on each of the left and right sides of the commutator 25. The carbon brushes 26 are held by brush holders 27. The brush holders 27 are supported by the cylindrical portion 41 of the motor housing 4. The carbon brushes 26 come into contact with the commutator 25.

[0070] The handle housing 5 accommodates the switch 72. The plunger 73 protrudes downward from the switch 72. A switch lever 74 is provided below the handle housing 5. The front end of the switch lever 74 can swing up and down with the rear end of the switch lever 74 as a fulcrum. The switch lever 74 is biased downward by a coil spring 75. The downward swing position of the switch lever 74 is the OFF position of the switch 72. The operator can push the switch lever 74 upward with the hand holding the handle housing 5. When the switch lever 74 is pushed upward, the plunger 73 is pushed in and the switch 72 is turned ON. A lock lever 76 is provided at the front end of the switch lever 74 so as to be rotatable in the front-rear direction. The lock lever 76 can be selected from a lock-off position that restricts the switch lever 74 from being pushed in, a neutral position that allows the switch lever 74 to be pushed in, and a lock-on position that maintains the switch lever 74 in a pushed-in state, by selecting a rotation position. A power cord 77 is connected to the rear end of the handle housing 5 .

[0071] The motor housing 4 and the handle housing 5 are fixed together by a number of screws 67. An opening 50 into which the screw 67 is inserted is provided at the front end of the handle housing 5. A screw hole 49 into which the threaded portion of the screw 67 is coupled is provided at the rear end of the motor housing 4.

[0072] A plurality of suction ports 78 are formed in the front part of the handle housing 5. When the rotor shaft 19 rotates and the fan 23 rotates, air around the housing 2 flows into the inside of the handle housing 5 through the suction ports 78. The air that has flowed into the inside of the handle housing 5 flows into the inside of the motor housing 4 through the air window 43. The air that has flowed into the inside of the motor housing 4 flows around the motor 16 to cool the motor 16, and then flows into the inside of the gear housing 3. The air that has flowed into the inside of the gear housing 3 is discharged to the outside of the housing 2 from the exhaust port 15.

[0073] In this embodiment, the power tool 1A has a rib portion 45 protruding from the bottom portion 42. The rib portion 45 protrudes forward from the bottom portion 42. A rear end portion, which is the rear end of the rib portion 45, is connected to a front surface, which is the front surface of the bottom portion 42. A front end portion, which is the front end of the rib portion 45, faces a rear surface of the insulator 172, which is disposed rearward of the stator core 171.

[0074] The front end of the rib portion 45 is disposed forward of the carbon brush 26. The rib portion 45 is disposed on at least a portion of the periphery of the commutator 25. The front end of the rib portion 45 is disposed on at least a portion of the periphery of the coil 173 which is disposed rearward of the stator core 171.

[0075] Fig. 12 is a schematic diagram of the motor housing 4 according to this embodiment as viewed from the rear side. As shown in Fig. 8 and Fig. 12, in this embodiment, when the motor housing 4 (motor 16) is viewed from the rear side, the rotor 18 rotates in only one direction, the clockwise direction, as indicated by the arrow Ra.

[0076] 12, a first reference circle A having a diameter 1 times the outer diameter of the commutator 25 and centered on the motor rotation shaft AX is defined on a predetermined plane perpendicular to the motor rotation shaft AX, a second reference circle B having a diameter 1.5 times the outer diameter of the commutator 25 and centered on the motor rotation shaft AX on the predetermined plane, and an annular range C between the first reference circle A and the second reference circle B are defined. In the predetermined plane, a position where a reference line RL passing through the center of the motor rotation shaft AX and the carbon brush 26 intersects with the second reference circle B is defined as a 0° position, and the opening ratio of the air window 43 in a first section C1 of the annular range C from the 0° position to the 90° position in the counter-rotation direction of the rotor 18 is defined as P1, and the opening ratio of the air window 43 in a second section C2 of the annular range C from the 0° position to the 90° position in the forward rotation direction of the rotor 18 is defined as P2. P1 <P2 …(1) The motor housing 4 is formed so as to satisfy the above condition. The opening ratio of the vents 43 refers to the ratio of the vents 43 to the bottom 42 per unit area. The outer diameter of the bottom 42 is more than 1.5 times the outer diameter of the commutator 25. The outer diameter of the bottom 42 may be 1.6 to 5.0 times the outer diameter of the commutator 25. The reference line RL extends in the left-right direction so as to pass through the motor rotation AX on a predetermined plane.

[0077] When the rotor 18 and the fan 23 rotate in the direction indicated by the arrow Ra, the air around the housing 2 flows into the inside of the handle housing 5 through the suction port 78. The air that flows into the inside of the handle housing 5 flows into the inside of the motor housing 4 through the vents 43. When dust is sucked into the suction port 78, the dust may flow into the inside of the motor housing 4 through the vents 43. When the dust that flows into the inside of the motor housing 4 is blown onto the contact point between the commutator 25 and the carbon brushes 26 shown in part D of FIG. 8, for example, the dust may become caught between the commutator 25 and the carbon brushes 26. When the commutator 25 rotates with the dust caught between the commutator 25 and the carbon brushes 26, the dust acts as an abrasive, causing wear of the commutator 25 and the carbon brushes 26, thereby reducing the durability of the motor 16.

[0078] In this embodiment, the position and size of the windshield 43 are adjusted and the rib portion 45 is provided so as to satisfy the conditions of the formula (1), whereby dust is prevented from being blown onto the portion D shown in FIG. 8. As a result, wear of the commutator 25 and the carbon brush 26 is suppressed, and the durability (wear resistance) of the motor 16 is improved.

[0079] As described above, in this embodiment, the grinder 1A includes a rotor 18 including a rotor shaft 19 to which the fan 23 and the commutator 25 are fixed, a stator 17 disposed around the rotor 18, and a carbon brush 26 that contacts the commutator 25, and the rotor 18 rotates only in one direction about a motor rotation axis AX extending in a predetermined direction (front-rear direction). The motor 16, a cylindrical portion 41 disposed around the motor 16, a bottom portion 42 connected to the cylindrical portion 41, and a windshield 43 provided in the bottom portion 42. The motor housing 4 that supports the stator 17 and the rib portion 45 that protrudes from the bottom portion 42 may be provided. The fan 23 may be fixed to a first portion of the rotor shaft 19 on one side of the center of the rotor shaft 19 in a predetermined direction. The commutator 25 may be fixed to a second portion of the rotor shaft 19 on the other side of the center of the rotor shaft 19 in a predetermined direction. The bottom portion 42 may be disposed on the other side of the commutator 25. The rib portion 45 may protrude from the bottom portion 42 to one side. On a predetermined plane orthogonal to the motor rotation axis AX, a first reference circle A having a diameter that is one times the outer diameter of the commutator 25 and centered on the motor rotation axis AX, and on the predetermined plane, having a diameter that is 1.5 times the outer diameter of the commutator 25, A second reference circle B centered on the motor rotation axis AX and an annular range C between the first reference circle A and the second reference circle B may be defined. On the predetermined plane, the position where the reference line RL passing through the center of the motor rotation axis AX and the carbon brush 26 intersects the second reference circle B is defined as the 0° position, and the opening ratio of the windshield 43 in the first section of the annular range from the 0° position to the 90° position in the reverse rotation direction of the rotor 18 is P1, and the opening ratio of the windshield 43 in the second section of the annular range from the 0° position to the 90° position in the forward rotation direction of the rotor 18 is P2. In this case, the condition P1 < P2 may be satisfied. One end of the rib portion 45 may be disposed on one side of the carbon brush 26.

[0080] In the above configuration, the intrusion of dust between the commutator 25 and the carbon brush 26 is suppressed. Due to the rotation of the fan 23, the dust around the housing 2 may enter the inside of the motor housing 4 through the suction port 78 and the air window 43. The rib portion 45 suppresses the intrusion of dust between the commutator 25 and the carbon brush 26. Also, when the condition of [P1 < P2] is satisfied, the intrusion of dust between the commutator 25 and the carbon brush 26 is suppressed. Therefore, the reduction in the life of the commutator 25 and the carbon brush 26 is suppressed.

[0081] In the present embodiment, the rib portion 45 may be disposed at least partially around the commutator 25.

[0082] In the above configuration, the intrusion of dust between the commutator 25 and the carbon brush 26 is suppressed.

[0083] In the present embodiment, the other end of the rib portion 45 may be connected to one surface of the bottom portion 42.

[0084] In the above configuration, the position of the rib portion 45 is stabilized.

[0085] In the present embodiment, the rib portion 45 may be integral with the bottom portion 42.

[0086] In the above configuration, the number of parts of the grinder 1A is reduced.

[0087] In the present embodiment, the stator 17 may include a stator core 171, an insulator 172 fixed to the stator core 171, and a coil 173 supported by the insulator 172. One end of the rib portion 45 may face the insulator 172.

[0088] In the above configuration, the intrusion of dust between the commutator 25 and the carbon brush 26 is suppressed.

[0089] In this embodiment, one end of the rib portion 45 may be disposed around at least a portion of the periphery of the coil 173 .

[0090] In the above configuration, the intrusion of dust between the commutator 25 and the carbon brushes 26 is suppressed.

[0091] In the present embodiment, the grinder 1A may include a bearing 29 that supports the other end of the rotor shaft 19. The bottom portion 42 may have a bearing holder 44 that holds the bearing 29.

[0092] In the above configuration, the rotor shaft 19 is supported on the bottom 42 via the bearing 29 .

[0093] [Second embodiment] A second embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0094] Fig. 13 is a perspective cross-sectional view showing a part of the grinder 1B according to this embodiment. Fig. 14 is a perspective view showing the rib member 30 according to this embodiment. As shown in Figs. 13 and 14, the rib portion 31 may be separate from the bottom portion 42. The rib portion 31 is provided on the rib member 30 which is separate from the motor housing 4. As shown in Fig. 14, a recess 33 in which the brush holder 27 is disposed is formed in a part of the rib member 30.

[0095] As described above, in this embodiment, the rib portion 31 may be separate from the bottom portion .

[0096] In the above configuration, the rib portion 31 can be easily processed into any shape.

[0097] In this embodiment, the rib portion 31 may have a recess 33 in which the brush holder 27 is disposed.

[0098] In the above configuration, interference between the brush holder 27 and the rib portion 31 is suppressed.

[0099] [Third embodiment] A third embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0100] Fig. 15 is a perspective cross-sectional view showing a part of a grinder 1C according to this embodiment. Fig. 16 is a perspective view showing an insulator 174 according to this embodiment.

[0101] In this embodiment, the grinder 1C includes a rib portion 1742 protruding from the insulator 174.

[0102] The insulator 174 has an insulator portion 1741 fixed to the rear end portion of the stator core 171, and a rib portion 1742 protruding rearward from the insulator portion 1741. The rib portion 1742 is integral with the insulator 174. The insulator 174 has the rib portion 1742.

[0103] The rear end, which is the other end of the rib portion 1742, is disposed rearward of the front end, which is the end on one side of the carbon brush 26. The rear end of the rib portion 1742 is disposed in at least a portion of the periphery of the commutator 25. The front end of the rib portion 1742 is connected to the insulator portion 1741. The rear end of the rib portion 1742 faces the front surface, which is one surface of the bottom portion 42.

[0104] The stator core 171 and the insulator 174 are fixed together by screws 60. The insulator portion 1741 is provided with openings 1745 into which the screws 60 are inserted.

[0105] As described above, in this embodiment as well, dust is prevented from entering between the commutator 25 and the carbon brushes 26. When the fan 23 rotates, dust around the housing 2 may enter the inside of the motor housing 4 through the suction port 78 and the air window 43. The rib portion 1742 prevents dust from entering between the commutator 25 and the carbon brushes 26. Therefore, a decrease in the life span of the commutator 25 and the carbon brushes 26 is suppressed.

[0106] [Fourth embodiment] A fourth embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0107] Fig. 17 is a perspective cross-sectional view showing a part of a grinder 1D according to this embodiment. Fig. 18 is a perspective view showing an inner baffle 32 according to this embodiment.

[0108] In this embodiment, the inner baffle 32 is disposed between the outer peripheral surface of the stator core 171 and the inner peripheral surface of the tubular portion 41. The inner baffle 32 includes an inner baffle 32A disposed between an upper portion of the outer peripheral surface of the stator core 171 and the inner peripheral surface of the tubular portion 41, and an inner baffle 32B disposed between a lower portion of the outer peripheral surface of the stator core 171 and the inner peripheral surface of the tubular portion 41. In the example shown in FIG. 12, at least a portion of the inner baffle 32A is disposed at a 90° position from the 0° position toward the counter-rotation direction of the rotor 18. At least a portion of the inner baffle 32B is disposed at a 90° position from the 0° position toward the forward rotation direction of the rotor 18.

[0109] The inner baffle 32 has a body portion 321 having an arc-shaped outer peripheral surface that conforms to the inner peripheral surface of the cylindrical portion 41, a protrusion portion 322 that protrudes radially inward from the body portion 321 and contacts the outer peripheral surface of the stator core 171, and a positioning portion 323 that is inserted into a recess provided in the stator core 171.

[0110] The inner baffle 32 prevents air that has flowed into the motor housing 4 through the air window 43 from passing between the outer circumferential surface of the stator core 171 and the inner circumferential surface of the cylindrical portion 41. The inner baffle 32 improves the air flow and prevents dust from accumulating near the commutator 25 and the carbon brushes 26.

[0111] As described above, in this embodiment as well, dust is prevented from entering between the commutator 25 and the carbon brushes 26. When the fan 23 rotates, dust around the housing 2 may enter the inside of the motor housing 4 through the suction port 78 and the air window 43. The inner baffle 32 improves the air flow and prevents the dust from remaining near the commutator 25 and the carbon brushes 26. This prevents the dust from entering between the commutator 25 and the carbon brushes 26. Therefore, a decrease in the lifespan of the commutator 25 and the carbon brushes 26 is suppressed.

[0112] [Fifth embodiment] A fifth embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0113] Fig. 19 is a perspective cross-sectional view showing a part of a grinder 1E according to this embodiment. Fig. 17 is a perspective view showing an insulator 175 according to this embodiment.

[0114] In this embodiment, the insulator 175 has an insulator portion 1751 fixed to the rear end portion of the stator core 171, a rear portion 1752 arranged on the rear side of the coil 173, and an inner portion 1753 arranged radially inward of the coil 173.

[0115] The stator core 171 and the insulator 175 are fixed together by screws 60. The insulator portion 1751 is provided with openings 1754 into which the screws 60 are inserted.

[0116] In this embodiment, a radially outer end of insulator portion 1751 protrudes radially outward beyond the outer circumferential surface of stator core 171. At least a portion of insulator portion 1751 is disposed between the outer circumferential surface of stator core 171 and the inner circumferential surface of tubular portion 41. An upper portion of insulator portion 1751 is disposed between an upper portion of the outer circumferential surface of stator core 171 and the inner circumferential surface of tubular portion 41. A lower portion of insulator portion 1751 is disposed between a lower portion of the outer circumferential surface of stator core 171 and the inner circumferential surface of tubular portion 41.

[0117] The insulator portion 1751 prevents air that has flowed into the motor housing 4 through the air window 43 from passing between the outer circumferential surface of the stator core 171 and the inner circumferential surface of the tube portion 41. The insulator portion 1751 improves the air flow and prevents dust from remaining near the commutator 25 and the carbon brushes 26.

[0118] As described above, instead of the inner baffle 32 described in the third embodiment, a part of the insulator 175 may be disposed between the outer peripheral surface of the stator core 171 and the inner peripheral surface of the tube portion 41. In this embodiment as well, dust is prevented from entering between the commutator 25 and the carbon brushes 26. Due to the rotation of the fan 23, dust around the housing 2 may enter the inside of the motor housing 4 through the suction port 78 and the air window 43. The insulator portion 1751 improves the air flow and prevents dust from remaining near the commutator 25 and the carbon brushes 26. This prevents dust from entering between the commutator 25 and the carbon brushes 26. Therefore, the life of the commutator 25 and the carbon brushes 26 is prevented from being reduced.

[0119] [Sixth embodiment] A sixth embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiments are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0120] Fig. 21 is a perspective cross-sectional view showing a part of a grinder 1F according to this embodiment. Fig. 22 is a perspective view showing an inner baffle 35 according to this embodiment. Fig. 23 is a cross-sectional view showing a part of a grinder 1F according to this embodiment.

[0121] In this embodiment, the grinder 1F includes an inner baffle 35 disposed between the insulator 172, which is disposed rearward of the stator core 171 in the front-rear direction, and the brush holder 27. The inner baffle 35 is annular. The inner baffle 35 is separate from the motor housing 4.

[0122] 12, in a predetermined plane perpendicular to the motor rotation shaft AX, a position where a reference line EL passing through the center of the motor rotation shaft AX and the carbon brush 26 intersects with a second reference circle B is defined as a 0° position. If the area (surface area) of the inner baffle 35 in a first section C1 of the annular range C from the 0° position to the 90° position in the counter-rotation direction of the rotor 18 is defined as S1, and the area (surface area) of the inner baffle 35 in a second section C2 of the annular range C from the 0° position to the 90° position in the forward rotation direction of the rotor 18 is defined as S2, S1>S2 …(2) The insulator 172 is formed so as to satisfy the above condition.

[0123] Further, the inner end of the inner baffle 35 is disposed more inward than the inner end of the insulator 172 in the radial direction of the motor rotating shaft AX.

[0124] The inner baffle 35 has openings 351 into which the screws 61 are inserted. The stator core 171, the insulator 172, and the inner baffle 35 are fixed together by the screws 61.

[0125] As described above, in this embodiment as well, dust is prevented from entering between the commutator 25 and the carbon brushes 26. When the fan 23 rotates, dust around the housing 2 may enter the inside of the motor housing 4 through the suction port 78 and the air window 43. The inner baffle 35 improves the air flow and prevents the dust from remaining near the commutator 25 and the carbon brushes 26. This prevents the dust from entering between the commutator 25 and the carbon brushes 26. Therefore, a decrease in the lifespan of the commutator 25 and the carbon brushes 26 is suppressed.

[0126] The inner baffle 35 may be integral with the motor housing 4, for example.

[0127] [Seventh embodiment] A seventh embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0128] In the above embodiment, the power tool is a grinder. However, the power tool may be a cutter.

[0129] Fig. 24 is a perspective view showing a cutter 1G according to this embodiment. Fig. 25 is a perspective view showing a cutter 1G according to this embodiment. Fig. 26 is a perspective view showing a motor housing 400 according to this embodiment. Fig. 27 is a perspective cross-sectional view showing a part of the cutter 1G according to this embodiment.

[0130] The cutter 1G has a motor housing 400 that houses the motor 16, a main body housing 200 that supports the blade, a base plate 300, a cover 350 that is disposed around a portion of the blade, a grip housing 260, and a power cord 770. Like the motor housing 4 described in the above embodiment, the motor housing 400 has a cylindrical portion 410, a bottom portion 420, a ventilating window 430, and a bearing holder 440.

[0131] 27, the motor 16 has a rotor shaft 19 and a commutator 250 fixed to the rotor shaft 19. The rear end of the rotor shaft 19 is supported by a bearing 290. The bearing 290 is held by a bearing holder 440.

[0132] A rib portion 450 protrudes leftward from the left surface of the bottom portion 420. The left end portion of the rib portion 450 is disposed to the left of the carbon brush 26.

[0133] The cutter 1G cuts an object to be cut. When the object to be cut is cut, dust is generated. By applying the components described in each of the above embodiments to the cutter 1G, deterioration of the commutator 250 and the carbon brushes 26 is suppressed. [Explanation of symbols]

[0134] 1A... grinder (power tool), 1B... grinder (power tool), 1C... grinder (power tool), 1D... grinder (power tool), 1E... grinder (power tool), 1F... grinder (power tool), 1G... cutter (power tool), 2... housing, 3... gear housing, 4... motor housing, 5... handle housing, 6... spindle, 7... bearing, 8... retainer, 9... bearing, 10... bevel gear, 11... inner flange, 12... outer flange, 13... disc-shaped grinding wheel, 14... wheel cover, 15...exhaust port, 16...motor, 17...stator, 18...rotor, 181...rotor core, 182...coil, 19...rotor shaft, 20...partition plate, 21...bearing, 22...bevel gear, 23...fan, 25...commutator, 26...carbon brush, 27...brush holder, 29...bearing, 30...rib member, 31...rib portion, 32...inner baffle, 32A...inner baffle, 32B...inner baffle, 33...recess, 35...inner baffle, 41...cylindrical portion, 42...bottom, 43...air window, 44...bearing holder, 45...rib part, 49...screw hole, 50...opening, 60...screw, 61...screw, 67...screw, 72...switch, 73...plunger, 74...switch lever, 75...coil spring, 76...lock lever, 77...power cord, 78...suction port, 171...stator core, 172...insulator, 173...coil, 174...insulator, 175...insulator, 200...main body housing, 250...commutator, 260...grip housing, 290...bearing, 300...base plate, 321...body part, 322...projection part, 32 3...positioning portion, 350...cover, 351...opening, 400...motor housing, 410...cylinder portion, 420...bottom, 430...ventilation window, 440...bearing retaining portion, 450...rib portion, 770...power cord, 1741...insulator portion, 1742...rib portion, 1745...opening, 1751...insulator portion, 1752...rear portion, 1753...inner portion, 1754...opening, A...first reference circle, AX...motor shaft, B...second reference circle, BX...output shaft, C...annular range, C1...first section, C2...second section, RL...reference line.

Claims

1. A motor comprising a rotor including a rotor shaft to which a fan and commutator are fixed, a stator arranged around the rotor, and carbon brushes in contact with the commutator, wherein the rotor rotates in only one direction around a motor rotation axis extending in a predetermined direction, A housing that supports the stator, having a cylindrical portion arranged around the motor, a bottom portion connected to the cylindrical portion, and a ventilation window provided in the bottom portion, It comprises a rib portion protruding from the bottom, The fan is fixed to a first portion of the rotor shaft on one side of the center of the rotor shaft in the predetermined direction. The commutator is fixed to the second portion of the rotor shaft on the other side of the center of the rotor shaft in the predetermined direction. The bottom portion is positioned on the other side of the commutator. The rib portion protrudes from the bottom portion to one side, In a predetermined plane perpendicular to the motor rotation axis, the first reference circle has a diameter one times the outer diameter of the commutator and is centered on the motor rotation axis, On the predetermined surface, a second reference circle having a diameter 1.5 times the outer diameter of the commutator and centered on the motor rotation axis, The annular range between the first reference circle and the second reference circle is defined, In the predetermined surface, the position where the reference line passing through the motor rotation axis and the center of the carbon brush intersects with the second reference circle is defined as the 0° position. P1 is the opening ratio of the wind window in the first division of the annular range from the 0° position to the 90° position in the counter-rotation direction of the rotor. When P2 is the opening ratio of the wind window in the second division of the annular range from the 0° position to the 90° position in the forward rotation direction of the rotor, P1 < P2, The following conditions are met: The one end of the rib portion is positioned to the one side of the carbon brush. Power tools.

2. The rib portion is positioned around at least a portion of the commutator. The power tool according to claim 1.

3. The other end of the rib portion is connected to the one side surface of the bottom portion. The power tool according to claim 1.

4. The rib portion is integral with the bottom portion. The power tool according to claim 1.

5. The rib portion is separate from the bottom portion. The power tool according to claim 1.

6. The stator comprises a stator core, an insulator fixed to the stator core, and a coil supported by the insulator. The one end of the rib portion faces the insulator, The power tool according to claim 1.

7. The one end of the rib portion is positioned in at least a portion of the coil's periphery. The power tool according to claim 6.

8. The rotor shaft is provided with a bearing that supports the other end of the rotor shaft, The bottom portion has a bearing retaining portion for holding the bearing. The power tool according to claim 1.

9. The brush holder comprises the carbon brush, The rib portion has a recess in which the brush holder is positioned. The power tool according to claim 1.

10. A motor comprising a rotor including a rotor shaft to which a fan and commutator are fixed, a stator disposed around the rotor and including a stator core, an insulator fixed to the stator core, and a coil supported by the insulator, and carbon brushes in contact with the commutator, wherein the rotor rotates around a motor rotation axis extending in a predetermined direction, A housing that supports the stator, having a cylindrical portion arranged around the motor, a bottom portion connected to the cylindrical portion, and a ventilation window provided in the bottom portion, The insulator comprises a rib portion protruding from the insulator, The fan is fixed to a first portion of the rotor shaft on one side of the center of the rotor shaft in the predetermined direction. The commutator is fixed to the second portion of the rotor shaft on the other side of the center of the rotor shaft in the predetermined direction. The bottom portion is positioned on the other side of the commutator. The rib portion protrudes from the insulator to the other side, The other end of the rib portion is positioned on the other side of the carbon brush than the one end of the carbon brush. Power tools.

11. The other end of the rib portion is positioned in at least a portion of the commutator's surroundings. The power tool according to claim 10.

12. The one end of the rib portion is connected to the insulator. The power tool according to claim 10.

13. The rib portion is integrated with the insulator. The power tool according to claim 10.

14. The other end of the rib portion faces the one side surface of the bottom portion, The power tool according to claim 10.

15. The rotor shaft is provided with a bearing that supports the other end of the rotor shaft, The bottom portion has a bearing retaining portion for holding the bearing. The power tool according to claim 10.

16. The stator core and the insulator are equipped with screws for fixing them together. The power tool according to claim 10.

17. A motor comprising a rotor including a rotor shaft to which a fan and commutator are fixed, a stator disposed around the rotor and including a stator core, an insulator fixed to the stator core, and a coil supported by the insulator, and carbon brushes in contact with the commutator, wherein the rotor rotates around a motor rotation axis extending in a predetermined direction, A housing that supports the stator, having a cylindrical portion arranged around the motor, a bottom portion connected to the cylindrical portion, and a ventilation window provided in the bottom portion, A brush holder supported by the cylindrical portion and holding the carbon brush, The system comprises an inner baffle positioned between the insulator and the brush holder in the predetermined direction, The fan is fixed to a first portion of the rotor shaft on one side of the center of the rotor shaft in the predetermined direction. The commutator is fixed to the second portion of the rotor shaft on the other side of the center of the rotor shaft in the predetermined direction. The bottom portion is positioned on the other side of the commutator. In a predetermined plane perpendicular to the motor rotation axis, the first reference circle has a diameter one times the outer diameter of the commutator and is centered on the motor rotation axis, On the predetermined surface, a second reference circle having a diameter 1.5 times the outer diameter of the commutator and centered on the motor rotation axis, The annular range between the first reference circle and the second reference circle is defined, In the predetermined surface, the position where the reference line passing through the motor rotation axis and the center of the carbon brush intersects with the second reference circle is defined as the 0° position. The area of ​​the inner baffle in the first division of the annular range from the 0° position to the 90° position in the counter-rotation direction of the rotor is S1, If S2 is the area of ​​the inner baffle in the second division of the annular range from the 0° position to the 90° position in the forward rotation direction of the rotor, S1 > S2, The following conditions are met: In the radial direction of the motor rotation shaft, the inner end of the inner baffle is positioned inward from the inner end of the insulator. Power tools.

18. The inner baffle is separate from the housing. The power tool according to claim 17.

19. The stator core and the insulator are equipped with screws for fixing them together. The inner baffle is fixed to the insulator by the screws. The power tool according to claim 17.

20. The inner baffle is integrated with the housing. The power tool according to claim 17.

Images