Power Tools

Abstract

The present invention provides an electric tool. A grinder (1) comprises an inner housing (3), a centrifugal fan (66), a cone (30), an expansion portion (31), and a rectifying portion (67), wherein the inner housing (3) is used to accommodate a brushless motor (4); the centrifugal fan (66) rotates as the brushless motor (4) is driven, thereby generating cooling air for the brushless motor (4) in the inner housing (3); the cone (30) and the expansion portion (31) are formed in the inner housing (3) and are used to accommodate the centrifugal fan (66); the rectifying portion (67) is arranged on the upstream side of the cooling air in a manner facing the centrifugal fan (66); the rectifying portion (67) is divided into inner and outer parts in the radial direction of the cone (30) and the expansion portion (31), the radial outer side being formed by the cone (30), and the radial inner side being formed by a baffle (55) assembled in the inner housing (3). Accordingly, the rectifying portion can be formed in a compact and space-saving structure in the axial direction.

Description

Technical Field

[0001] The present invention relates to an electric tool such as a grinder having a fan for cooling a motor. Background Art

[0002] In electric tools such as grinders, a fan for cooling the motor is mounted on the output shaft of the motor, and the fan rotates as the motor is driven, sucking air from outside the housing to generate cooling wind for the motor, thereby cooling the motor. The fan is housed in a cylindrical portion provided on the housing.

[0003] In this case, in order to smoothly circulate the cooling air sucked by the fan, as disclosed in Patent Document 1, a baffle plate having a mortar-shaped rectifying portion facing the upstream side of the fan is provided on the cylindrical portion of the casing.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 2018-111185 Summary of the invention

[0007] [Technical problem to be solved by the invention]

[0008] Sometimes, the cylindrical portion of the housing that accommodates the fan is formed in an extended manner in order to hold the baffle. In this case, the extended portion overlaps the baffle in the axial direction, thereby increasing the axial length of the housing and creating a useless space. Although it is also considered to directly set the rectifying part on the housing, it is necessary to extend the rectifying part from the inner surface of the housing to the center side, which makes it difficult to form.

[0009] Therefore, an object of the present invention is to provide an electric power tool in which a rectifying portion can be formed with a compact and space-saving structure in the axial direction.

[0010] [Technical solutions for solving technical problems]

[0011] In order to achieve the above object, the present invention is characterized in that it includes a housing, a fan, a cylindrical portion and a rectifying portion, wherein:

[0012] The housing is used to accommodate the motor;

[0013] The fan rotates as the motor is driven, thereby generating cooling wind for the motor in the housing;

[0014] The cylindrical portion is formed on the housing and is used to accommodate the fan;

[0015] The rectifying portion is disposed on the upstream side of the cooling air so as to face the fan.

[0016] The rectifying portion is divided into two parts, an inner part and an outer part, in the radial direction of the cylindrical portion. The radial outer side is formed by the cylindrical portion, and the radial inner side is formed by a baffle assembled to the housing.

[0017] Another aspect of the present invention is characterized in that, in addition to the above-mentioned configuration, the baffle has a contact portion that contacts the stator of the motor in an axial direction thereof.

[0018] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, the baffle is screwed to the housing, thereby fixing the stator via the abutment portion.

[0019] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, a screw passage portion for passing a screw for threading and fastening the baffle is provided in the rectifying portion.

[0020] Another aspect of the present invention is characterized in that, in the above-mentioned configuration, the screw passage portion is a through hole formed across the cylindrical portion and the baffle.

[0021] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, a spacer is provided in a detachable manner with respect to the housing, and the spacer blocks the screw passing portion after the baffle is screwed to form a continuous surface between the cylindrical portion and the baffle.

[0022] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, an outer shell connected to the outer side of the shell via an elastic body is provided, and the spacer is formed as a part of the elastic body.

[0023] Another aspect of the present invention is characterized in that, in addition to the above-mentioned configuration, the spacer positions the housing relative to the elastic body.

[0024] Another aspect of the present invention is characterized in that, in addition to the above-mentioned configuration, the screw passes through the screw passing portion in parallel with the axis of the housing, penetrates the baffle plate, and is screwed into the housing.

[0025] Another aspect of the present invention is characterized in that, in addition to the above-mentioned configuration, a pair of screws and screw passages are provided at point-symmetrical positions about the axis line.

[0026] Another aspect of the present invention is characterized in that, in the above-mentioned structure, the elastic body is annular.

[0027] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, the outer shell is divided into a pair of split shells.

[0028] Another aspect of the present invention is characterized in that, in addition to the above-described configuration, the housing is rotatably connected to the outer housing via a connection shaft extending in a predetermined direction.

[0029] Another aspect of the present invention is characterized in that, in addition to the above-mentioned structure, the connecting shaft penetrates the housing, and both ends thereof are held by the outer housing via a second elastic body.

[0030] [Effects of the invention]

[0031] According to the present invention, the rectifying portion can be formed by using a part of the housing and the baffle, thereby preventing the axial length of the housing from being increased or generating a useless space.

[0032] In particular, if a contact portion that contacts the stator in the axial direction of the stator is provided on the baffle plate, the stator can be positioned by the baffle plate.

[0033] Furthermore, if the baffle is screwed to the housing to fix the stator by the contact portion, the baffle can be fixed at the same time as the stator.

[0034] Furthermore, if a screw passage portion for passing a screw for screw-fastening the baffle is provided in the rectifying portion, the screw can be arranged at a position close to the housing and the stator, thereby maintaining the compactness of the housing.

[0035] Furthermore, if the screw passage portion is formed as a through hole formed so as to straddle the cylindrical portion and the baffle plate, the screw passage portion can be formed without significantly changing the shape of the rectifying portion.

[0036] Furthermore, if a spacer is provided detachably from the housing and blocks the screw passage after the baffle is screwed to form a continuous surface between the cylindrical portion and the baffle, the function of the rectifying portion will not be reduced even if the screw passage is provided.

[0037] In addition, if an outer housing connected via an elastic body is provided on the outer side of the housing, and the spacer is formed as a part of the elastic body, the spacer can be easily assembled together with the elastic body.

[0038] Furthermore, if the spacer is used to position the housing relative to the elastic body, the housing can be easily positioned using the elastic body. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a three-dimensional diagram of a grinding machine.

[0040] Figure 2 is a top view of the grinding machine.

[0041] Figure 3 This is the left side view of the grinding machine.

[0042] Figure 4 It is a central longitudinal section view of the grinding machine.

[0043] Figure 5 yes Figure 4 An enlarged view of the front part of the grinding machine.

[0044] Figure 6 yes Figure 5 AA section view.

[0045] Figure 7 It is a perspective exploded view showing the elastic retaining structure of the inner shell.

[0046] Figure 8 The diagrams are explanatory diagrams of an inner casing assembled with a stator and a baffle, wherein (A) is a front view and (B) is a central longitudinal sectional view.

[0047] Fig. 9 (A) is Figure 5 (B) is the BB section view, and (B) is the CC section view.

[0048] Fig.10 (A) is Figure 5 (B) is the DD cross-sectional view, and (B) is the EE cross-sectional view.

[0049] Fig.11 yes Figure 5 FF cross-sectional view.

[0050] Fig.12 It is a perspective view of the front part of the grinding machine (the outer case is omitted) showing a modified example of the positioning structure of the outer case and the inner case.

[0051] Fig.13 It is a cross-sectional view corresponding to DD, showing a modified example of the positioning structure between the outer case and the inner case.

[0052] [Explanation of Reference Numerals]

[0053] 1: rechargeable grinder; 1a: tool body; 2: outer shell; 3: inner shell; 4: brushless motor; 5: gear housing; 6: spindle; 7: front cylinder; 8: rear cylinder; 9: battery mounting portion; 10: large diameter portion; 11: battery pack; 20: controller; 21: control circuit substrate; 23: acceleration sensor; 26: auxiliary handle; 36: fitting convex portion; 37: bearing holding portion; 40: stator; 41: rotor; 55: stopper Plate; 60: rotating shaft; 67: rectifying part; 68: through hole; 70: connecting rod; 71: rod receiving part; 73: rubber end cap; 74: tubular rubber; 77: inner positioning protrusion; 77a: front surface; 78: groove; 79: inner positioning groove; 80: outer positioning protrusion; 81: receiving recess; 84: handle mounting part; 97: top tool; 100A~100C: incision; 101: inner protrusion; 102: outer protrusion. DETAILED DESCRIPTION

[0054] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0055] Figure 1 It is a perspective view showing an example of a grinding machine. Figure 2 is a top view of the grinding machine. Figure 3 This is the left side view of the grinding machine. Figure 4 It is a central longitudinal section view of the grinding machine.

[0056] The grinding machine 1 has a tool body 1a extending in the front-rear direction. A spindle 6 is provided downwardly at the front of the tool body 1a. A tip tool 97 such as a disc-shaped grinding wheel can be mounted on the lower end of the spindle 6.

[0057] The tool body 1a includes a cylindrical outer shell 2 and a cylindrical inner shell 3 held on the front side of the outer shell 2. Figure 5 As shown, the inner housing 3 is used to hold the brushless motor 4 and protrudes forward from the outer housing 2. In addition, the tool body 1a also has a gear housing 5 connected to the front side of the inner housing 3. The gear housing 5 allows the spindle 6 to protrude downward.

[0058] The outer shell 2 is made of resin in which a large-diameter front cylinder 7, a small-diameter rear cylinder 8, and a battery mounting portion 9 are integrally formed. The front cylinder 7 is used to hold the inner shell 3. The rear cylinder 8 is formed at a position eccentric to the rear and upward of the front cylinder 7. The rear cylinder 8 is used as a main handle. The battery mounting portion 9 is formed at the rear end of the rear cylinder 8. The outer shell 2 is formed by assembling a pair of left and right split shells 2a and 2b by screws. The front end of the front cylinder 7 becomes a large-diameter portion 10 that is further expanded forward. The battery pack 11 that serves as a power source can be slidably mounted on the battery mounting portion 9 from above.

[0059] A main switch 12 is disposed on the rear tube 8 of the outer shell 2, and the main switch 12 causes the plunger 13 to protrude downward. The main switch 12 is a mechanical contact that allows conduction from the later-described connection terminal 25 to the control circuit substrate 21 by a switch-on action. In addition, a micro switch 14 is disposed on the rear tube 8 on the front side of the main switch 12, and the micro switch 14 causes the button portion 15 to protrude downward. The micro switch 14 is an electrical contact that allows conduction from the control circuit substrate 21 to the brushless motor 4 by a switch-on action. A switch lever 16 is disposed on the lower side of the outer shell 2 in a manner that can swing in the up and down directions. The switch lever 16 extends backward while being bent from the front tube 7 in a manner that matches the shape of the lower surface of the rear tube 8, with the front end as a fulcrum. The switch lever 16 is normally urged to a protruding position that protrudes downward by a coil spring 17 disposed between the rear portion thereof and the lower surface of the rear tube 8.

[0060] A push plate 18 is provided on the switch lever 16. The push plate 18 pushes the switch lever 16 upward to push the plunger 13 of the main switch 12. An unlock lever 19 is provided on the switch lever 16 in front of the push plate 18. The unlock lever 19 is normally rotated by a force. Figure 4 The longitudinal posture of the unlocking lever 19 is thereby limited to limit the push on the switch operating lever 16. Figure 4 The unlocking lever 19 is rotated to the left by the fingers holding the rear tube 8, thereby allowing the switch lever 16 to be pushed. Accordingly, if the switch lever 16 is held after the unlocking lever 19 is rotated to the left by the fingers holding the rear tube 8, the push plate 18 of the switch lever 16 pushes the plunger 13 of the main switch 12. Then, the unlocking lever 19 pushes the button 15 of the micro switch 14.

[0061] A controller 20 is housed behind the main switch 12. The controller 20 is supported in an inclined posture with the lower end located forward of the upper end relative to the axis of the rear cylinder portion 8 of the outer shell 2. The controller 20 is configured by housing a control circuit board 21 in an aluminum disk-shaped outer shell 22. The control circuit board 21 is equipped with six FETs (not shown) corresponding to the coils 45 of the brushless motor 4, a capacitor, a microcomputer (not shown), and the like.

[0062] In addition, the control circuit substrate 21 is equipped with an acceleration sensor 23. The acceleration sensor 23 includes a 3-axis acceleration sensor element. The 3-axis acceleration sensor element is, for example, a MEMS (MicroElectro Mechanical System) type having a movable electrode portion and a detection electrode portion. Here, the movable electrode portion is shaken in response to the acceleration applied from the outside, thereby changing the gap between the movable electrode portion and the detection electrode portion. As a result, the electrostatic capacitance generated between the two electrode portions changes in response to the change in the gap, thereby detecting acceleration.

[0063] A plurality of slit-shaped air inlets 24, 24, ... are formed on the left and right sides of the battery mounting portion 9 behind the controller 20. A terminal block 25 is held in a vertical position behind the air inlet 24. The terminal block 25 is electrically connected to the battery pack 11 slidably mounted from above.

[0064] In this way, electronic components other than the brushless motor 4 are accommodated at the rear of the inner case 3 and are accommodated in the outer case 2 .

[0065] The inner housing 3 is made of resin and has a smaller diameter than the front cylinder 7 of the outer housing 2 and is accommodated in the front cylinder 7. The front end of the inner housing 3 protrudes forward from the outer housing 2. Figure 6 As shown, a cone portion 30 and an expansion portion 31 are formed at the front end of the inner housing 3, wherein the cone portion 30 gradually increases in diameter as it moves forward; and the expansion portion 31 extends forward from the front end of the cone portion 30. The expansion portion 31 has a substantially square shape when viewed from the front.

[0066] like Figure 7 and Fig. 9 (B) and Fig.10 As shown, four receiving portions 32, 32, ... protruding toward the axial center are formed on the inner surface of the inner housing 3. Each receiving portion 32 is formed along the front-rear direction at equal intervals in the circumferential direction. Fig.10 As shown in (B), a locking portion 33 having a triangular cross section is formed at the rear portion of each receiving portion 32, and the protrusion amount of the locking portion 33 toward the axial center side is larger than that of the front portion.

[0067] In the inner housing 3, a pair of slits 34, 34 are formed at point-symmetrical positions above and below the axis. Each slit 34 extends rearward from the tapered portion 30 with a notch formed at the front end. Behind each slit 34, on the extension line of the front end of the slit 34, a screw boss portion 35 protruding toward the outer surface of the inner housing 3 is formed.

[0068] In addition, a fitting protrusion 36 is formed on the right side surface of the inner housing 3. The fitting protrusion 36 is in the shape of a band having a predetermined width vertically and is formed from the tapered portion 30 to the rear end of the inner housing 3 along the front-rear direction.

[0069] Furthermore, a bearing holding portion 37 that closes the rear portion is provided in the rear portion of the inner housing 3. The bearing holding portion 37 is held at the axis of the inner housing 3 by four radially connected connecting plates 38, 38, etc. connected to the inner surface of the inner housing 3. The bearing holding portion 37 has its rear portion protruding rearward from the inner housing 3. A through hole 39 that penetrates vertically is formed at the rear portion of the bearing holding portion 37.

[0070] The brushless motor 4 is an inner rotor type composed of a cylindrical stator 40 and a rotor 41 penetrating the inside thereof. The stator 40 has a cylindrical stator core 42 formed of a plurality of laminated steel plates. In addition, the stator 40 has a front insulator 43 and a rear insulator 44 on the axial front and rear end surfaces of the stator core 42. In addition, the stator 40 has a plurality of coils 45, 45, etc. wound around the stator core 42 through the front insulator 43 and the rear insulator 44. Figure 7 and Fig. 9 As shown in FIG. 1B , a pair of front notch portions 46 , 46 having arc-shaped concave cross sections are formed on the upper and lower surfaces of the front insulator 43 .

[0071] A sensor circuit board 47 is provided on the rear insulator 44 for detecting the position of the permanent magnet 62 inserted into the rotor core 61. A wiring member 48 is mounted on the rear insulator 44 on the rear side of the sensor circuit board 47. The wiring member 48 includes a terminal connector 49 for connecting each coil 45 via a fusion terminal 50. Figure 7 and Fig.10 As shown in FIG. 2 (B), four rear notch portions 51 , 51 . . . are formed on the rear insulator 44 so as to be aligned with the phases of the four locking portions 33 of the inner housing 3 .

[0072] Here, the stator 40 is inserted from the front of the inner housing 3 in such a manner that the four rear notches 51 are aligned with the four locking portions 33. Fig.10 As shown in (B), each stopper 33 is locked with each rear notch 51, and the stator 40 is restricted from moving backward while being stopped. In this state, except for the stopper 33, the inner surface of each receiving portion 32 abuts against the outer surface of the stator core 42 to hold the stator 40.

[0073] A baffle 55 is assembled from the front inside the inner housing 3 at the front side of the stator 40. The baffle 55 is annular, and its front surface is a tapered surface that is continuously connected to the front surface of the tapered portion 30. A pair of small cylindrical portions 56, 56 are provided at the upper and lower parts of the baffle 55 to protrude radially outward. The small cylindrical portions 56, 56 are fitted into the slits 34, 34 of the inner housing 3, and abut against the screw boss portions 35, 35 from the front. Figure 5 and Fig. 9 As shown in (B), front pressing portions 57, 57 are integrally formed on the radially inner side of each small cylindrical portion 56. The front pressing portions 57, 57 protrude radially inward from the inner circumferential surface of the inner housing 3 and have an arc-shaped cross section.

[0074] The baffle 55 is assembled from the front to the inner housing 3 into which the stator 40 is inserted. At this time, the upper and lower small cylinders 56, 56 are positioned in front of the screw bosses 35, 35 through the slits 34, 34 and are pushed backward. Figure 5 and Figure 8 As shown, the front pressing portions 57 , 57 are fitted into the front notch portions 46 , 46 of the front insulator 43 and abut against the front surface of the stator core 42 , thereby positioning the stator 40 from the front.

[0075] In this positioned state, the cone 30 and the baffle 55 form a mortar-shaped rectifying portion 67 located on the rear side of a centrifugal fan 66 described later and composed of the cone 30 located radially outside the inner casing 3 and the baffle 55 located radially inside.

[0076] The rectifying portion 67 has through holes 68, 68 formed in a circular shape when viewed from the front, at a position across the cone 30 and the baffle 55 and in front of the screw bosses 35, 35 and the front pressing portions 57, 57. The through holes 68, 68 are formed by the semicircular front ends of the slits 34, 34 formed in a notch shape in the cone 30 and the semicircular recesses 55a, 55a provided on the outer peripheral surface of the baffle 55. Figure 6 , Figure 7 As shown, a protrusion 55 b for closing a notch formed on the front surface of the tapered portion 30 by the fitting protrusion 36 is formed on the right side of the front end of the baffle 55 .

[0077] In this state, screws 58, 58 that penetrate the small cylindrical portions 56, 56 from the front through the through holes 68, 68 are screwed into the screw boss portions 35, 35. Thus, the baffle plate 55 is fixed at a position where its front surface is continuously connected to the front surface of the cone portion 30 to form the rectifying portion 67. At the same time, the stator 40 is clamped and fixed between the baffle plate 55 and the locking portion 33.

[0078] The rotor 41 has a rotating shaft 60 located at the axis and a rotor core 61 arranged around the rotating shaft 60. The rotor core 61 is formed by stacking a plurality of steel plates and has a substantially cylindrical shape. In addition, the rotor 41 has four plate-shaped permanent magnets 62, 62, ... fixed inside the rotor core 61.

[0079] The rear end of the rotating shaft 60 is axially supported by a bearing 63 held by a bearing holding portion 37. The front end of the rotating shaft 60 is axially supported by a partition plate 64 through a bearing 65, wherein the partition plate 64 is assembled between the gear housing 5 and the expansion portion 31 of the inner housing 3. In this state, the top end of the rotating shaft 60 protrudes into the gear housing 5. A centrifugal fan 66 is mounted on the rotating shaft 60 behind the partition plate 64. The centrifugal fan 66 is housed on the front side of the baffle 55 in a manner that starts from the tapered portion 30 of the inner housing 3 and spans the expansion portion 31. The rectifying portion 67 faces the outer periphery of the rear surface of the centrifugal fan 66.

[0080] (Description of the elastic retaining structure of the inner shell)

[0081] The inner housing 3 holding the brushless motor 4 is elastically held by the outer housing 2. Next, this elastic holding structure will be described in detail.

[0082] A metal connecting rod 70 is passed through the through hole 39 of the bearing holding portion 37 of the inner housing 3 in the up-down direction. Figure 7 and Fig.11 As shown, the upper and lower ends of the connecting rod 70 are supported by a pair of upper and lower rod receiving parts 71, 71 respectively formed on the split shells 2a, 2b of the outer shell 2. Each rod receiving part 71 is a square cylinder. Insertion holes 72, 72 for the connecting rod 70 are formed on the alignment surfaces of the left and right rod receiving parts 71, 71. Inside each insertion hole 72, a rubber end cap 73 for receiving the end of the connecting rod 70 is respectively retained.

[0083] Accordingly, the connecting rod 70 passing through the rear portion of the bearing holding portion 37 is supported by the rod receiving portion 71, whereby the inner housing 3 is held in a manner capable of swinging left and right around the connecting rod 70. The upper and lower ends of the connecting rod 70 serving as a fulcrum are elastically held by the rod receiving portions 71, 71 through rubber end caps 73, 73.

[0084] On the outer periphery of the inner housing 3, a cylindrical rubber 74 is detachably mounted from the tapered portion 30 to the rear portion. The cylindrical rubber 74 is sandwiched between the large diameter portion 10 of the outer housing 2 and the inner housing 3. Figure 5 and Figure 7As shown, arc-shaped flanges 75, 75 are formed along the rear surface of the cone 30 at the upper and lower parts of the front end of the cylindrical rubber 74. Recesses 76, 76 whose contact area with the cone 30 is smaller than that of the flanges 75, 75 are formed at the left and right parts of the front end of the cylindrical rubber 74.

[0085] Thus, the entire circumference of the front portion of the inner housing 3 that can swing left and right around the connecting rod 70 is elastically held on the outer housing 2 by the cylindrical rubber 74. Here, the hardness of the rubber cap 73 is lower than that of the cylindrical rubber 74.

[0086] A pair of inner positioning protrusions 77, 77 are formed on the inner circumference of the cylindrical rubber 74 at upper and lower positions near the front end. The inner positioning protrusions 77, 77 are engaged with the through holes 68, 68 provided in the rectifying portion 67. In this state, the inner positioning protrusions 77, 77 serve as spacers for blocking the front of the screws 58, 58 for fixing the baffle 55. At the same time, as shown in FIG. Figure 5 As shown, the front surfaces 77a, 77a of the inner positioning protrusions 77, 77 are continuous with the front surfaces of the cone 30 and the baffle 55. Grooves 78 are formed along the front-to-back direction on the inner circumferential surface of the cylindrical rubber 74 behind each inner positioning protrusion 77. Each groove 78 is fitted with the screw boss 35 of the inner housing 3.

[0087] A positioning groove 79 is formed on the right inner peripheral surface of the cylindrical rubber 74 over the entire length thereof. The positioning groove 79 is fitted with the fitting protrusion 36 of the inner housing 3 .

[0088] A pair of outer positioning protrusions 80, 80 projecting radially outward are formed on the left and right side surfaces of the rear end of the cylindrical rubber 74. A pair of receiving recesses 81, 81 into which the outer positioning protrusions 80, 80 fit are formed on the left and right inner surfaces of the outer housing 2.

[0089] A fixing ring 82 is attached to the outer periphery of the cylindrical rubber 74 behind the tapered portion 30. The fixing ring 82 is made of metal and has the same outer diameter as the large diameter portion 10. A pair of flat surfaces 83, 83 are formed on both left and right side surfaces of the fixing ring 82 in the vertical direction.

[0090] like Figure 2 and Figure 6 As shown in the figure, a pair of handle mounting parts 84, 84 are integrally formed on the left and right side surfaces of the front end of the outer shell 2. The handle mounting parts 84, 84 extend outward from the outer shell 2 to the left and right sides and extend forward to the outside of the gear housing 5. Each handle mounting part 84 is used for the auxiliary handle 26 ( Figure 1 , Figure 2Each handle mounting portion 84 is formed in a plate shape along a plane defined in the up-down and front-back directions, and is non-contacting with the outer surface of the inner housing 3 and the partition plate 64. Fig. 9 As shown in (A), the handle mounting portion 84 is screwed and fastened to the fixing ring 82 from the left and right outer sides by a pair of upper and lower screws 85, 85, with the inner surfaces of the handle mounting portions 84, 84 abutting against the flat surfaces 83, 83 of the fixing ring 82. In this way, the left and right split shells 2a, 2b of the outer shell 2 are screwed and fastened to the fixing ring 82 through the handle mounting portions 84, 84 in addition to being screwed and fastened to each other.

[0091] On each handle mounting portion 84, a frame portion 86 is protrudingly provided between the upper and lower screws 85, 85. Figure 6 As shown, a threaded hole 87 is formed inside the frame portion 86 in the left-right direction, and the threaded hole 87 is used to screw in a screw portion 27 provided at the top end of the sub-handle 26 to fix it.

[0092] On the other hand, Figure 1 and Figure 2 As shown, at the four corners when viewed from the front, four screws 90, 90 ... are screwed into the inner housing 3 through the partition plate 64 to fix the gear housing 5. A bevel gear 91 is fixed to the front end of the rotating shaft 60 protruding into the gear housing 5. Figure 4 As shown, the bevel gear 91 meshes with the bevel gear 92 fixed to the upper end of the main shaft 6. A plurality of exhaust ports 93, 93 ... are formed on the front surface of the gear housing 5, and are connected to the inner housing 3 through a through hole (not shown) provided in the partition plate 64. A shaft locking member 94 is provided in front of the exhaust port 93, and the shaft locking member 94 can lock the rotation of the main shaft 6 through the bevel gear 92 by a pushing operation.

[0093] The main shaft 6 is axially supported by upper and lower bearings 96, 96, and the upper and lower bearings 96, 96 are held by the gear housing 5 and a bearing box 95 assembled to the lower part of the gear housing 5. The main shaft 6 protrudes downward from the bearing box 95, and a top tool 97 can be mounted on its lower end. A wheel cover (not shown) for covering the rear half of the top tool 97 can be mounted on the outer periphery of the bearing box 95.

[0094] (Operation description of grinding machine)

[0095] In the grinder 1 configured as above, the unlocking lever 19 is rotated by the fingers holding the rear cylinder 8 to unlock the machine. In this state, the switch lever 16 is held. Then, as described above, the pressing plate 18 presses the plunger 13 to turn on the main switch 12. Accordingly, the power from the battery pack 11 is supplied to the control circuit board 21 of the controller 20.

[0096] If the switch lever 16 is further held, the unlock lever 19 pushes the button portion 15 of the micro switch 14, and the micro switch 14 is turned on. Then, the control circuit board 21, which receives the on signal of the micro switch 14, supplies the power obtained from the battery pack 11 to the brushless motor 4, so that the brushless motor 4 is started. Accordingly, the rotating shaft 60 rotates together with the rotor 41, and the main shaft 6 rotates (rotates to the right when viewed from above) through the bevel gears 91 and 92. In this way, the top tool 97 can be used for grinding operations, etc.

[0097] Here, since there is imbalance in the rotor 41 of the brushless motor 4 rotating at high speed and in the tip tool 97 attached to the spindle 6 , the imbalance becomes a vibration source and transmits vibration to the inner housing 3 and the gear housing 5 .

[0098] However, a cylindrical rubber 74 is interposed between the inner housing 3 and the outer housing 2. Therefore, vibration is effectively insulated, and the vibration transmitted to the outer housing 2 is reduced. Accordingly, it is not easy for the vibration to be transmitted to the hand of the operator holding the rear cylinder 8 as the main handle. In addition, since the sub-handle 26 is also mounted on the handle mounting portion 84 of the outer housing 2 from which vibration is insulated, it is not easy for the vibration to be transmitted to the hand of the operator holding the sub-handle 26, thereby achieving low vibration.

[0099] Furthermore, when the brushless motor 4 is started or a load is applied to the rotating top tool 97, the inner housing 3 attempts to rotate in the left direction (the direction of the reaction force) when viewed from above, with the connecting rod 70 as the center. However, since the cylindrical rubber 74 is sandwiched between the inner housing 3 and the outer housing 2, the rotation of the inner housing 3 is buffered by the cylindrical rubber 74, making it difficult for the reaction force to be transmitted to the outer housing 2 and the sub-handle 26 mounted on the outer housing 2.

[0100] On the other hand, when the centrifugal fan 66 rotates with the rotation of the rotating shaft 60, the outside air is sucked from the rear air inlet 24, and the air bypasses the controller 20 from below and moves into the outer housing 2. Thus, the controller 20 and the connection terminals 25 are cooled.

[0101] The airflow in the outer housing 2 passes through the main switch 12 and the micro switch 14 to cool the brushless motor 4. Then, the airflow enters the inner housing 3 and passes between the stator 40 and the rotor 41 of the brushless motor 4 to cool the brushless motor 4. Then, the airflow passes from the rectifying portion 67 through the expansion portion 31 and the partition plate 64 to the gear housing 5 and is discharged to the outside from the exhaust port 93.

[0102] Furthermore, the control circuit board 21 detects acceleration through the acceleration sensor 23 during the driving process of the brushless motor 4. Then, the detected acceleration is compared with the threshold value pre-recorded in a storage unit such as a ROM. During the operation, when a recoil (a phenomenon in which the tool body 1a suddenly rebounds to the operator's side when the top tool 97 is embedded in the workpiece or collides with a hard object) or a shake (a phenomenon in which the top tool 97 is locked by the workpiece and the tool body 1a rotates around the spindle 6) occurs, the threshold value is based on the value of the acceleration generated at this time. Accordingly, if the detected acceleration exceeds the threshold value, the control circuit board 21 stops the driving of the brushless motor 4.

[0103] Here, a cylindrical rubber 74 is interposed between the inner housing 3 having a vibration source and the outer housing 2 having the rear cylinder 8 and the sub-handle 26 held by the operator. Thus, the vibration generated during normal operation is mitigated and not transmitted to the acceleration sensor 23. Therefore, the durability of the acceleration sensor 23 can be ensured, and false detection is not likely to occur, so that the acceleration when a recoil or shaking occurs can be determined with high accuracy.

[0104] (Effects of the invention related to positioning of the inner shell and the outer shell by the cylindrical rubber)

[0105] The grinding machine 1 of the above-mentioned method includes an inner housing 3, a spindle 6 (final output shaft) and an outer housing 2, wherein the inner housing 3 accommodates a brushless motor 4 (motor); the spindle 6 is arranged in front of the brushless motor 4 and faces downward; the outer housing 2 is provided with the inner housing 3 on the inner side and is integrally provided with a rear cylinder 8 (handle). In addition, the inner housing 3 and the outer housing 2 are connected in a manner that can rotate relative to each other through a connecting rod 70 (connecting shaft) extending in a prescribed direction. On the other hand, the inner housing 3 is held in the outer housing 2 by a cylindrical rubber 74 (elastic body) arranged in front of the connecting rod 70. In addition, the cylindrical rubber 74 is provided with an inner positioning protrusion 77 and an inner positioning groove 79 (internal positioning portion) for positioning the inner housing 3; and an outer positioning protrusion 80 (external positioning portion) for positioning the outer housing 2.

[0106] With this structure, even if the cylindrical rubber 74 is interposed between the inner housing 3 and the outer housing 2, the two housings 2 and 3 can be accurately positioned, thereby achieving an effective vibration-proofing effect.

[0107] In particular, the inner housing 3 has a cylindrical shape extending in the front-rear direction, and the cylindrical rubber 74 has an annular shape attached to the outer circumference of the inner housing 3. Thus, a uniform vibration-proofing effect can be obtained over the entire circumference.

[0108] The external positioning portion is an external positioning protrusion 80 that protrudes radially outward from the cylindrical rubber 74 and engages with a receiving recess 81 formed on the inner surface of the outer housing 2. This makes it possible to easily position the outer housing 2.

[0109] In addition, the inner positioning portion is an inner positioning groove 79 (inner positioning recess) which is recessed in the inner surface of the cylindrical rubber 74 and is engaged with the engaging protrusion 36 formed on the outer surface of the inner housing 3. In addition, inner positioning protrusions 77, 77 (inner positioning protrusions) are used as the inner positioning portion, which are protrudingly provided on the inner surface of the cylindrical rubber 74 and engage with the slit 34 formed in the inner housing 3. Thus, the inner housing 3 can be easily positioned.

[0110] In addition, the connecting rod 70 is arranged in the up-down direction at the rear end of the inner housing 3. According to this, the inner housing 3 can be supported so as to be swingable in the left-right direction, and can effectively buffer the recoil.

[0111] The outer housing 2 is divided into left and right split housings 2a and 2b, and a pair of left and right outer positioning protrusions 80 and 80 are provided, and are engaged with the split housings 2a and 2b, respectively.

[0112] In addition, the front end of the cylindrical rubber 74 is provided with escape portions 76, 76 on both the left and right sides, and the escape portions 76, 76 make the contact area with the outer housing 2 smaller than that on the upper and lower sides. Thus, the inner housing 3 is allowed to rock to the left and right (left and right on the rotation plane of the top tool 97) to a certain extent, and the cushioning effect achieved by the cylindrical rubber 74 can be obtained.

[0113] In addition, the connecting rod 70 penetrates the inner housing 3, and both ends are held by the outer housing 2 via rubber end caps 73 (second elastic body). According to this, the connecting rod 70 is also elastically supported, which contributes to improving the vibration-proof effect.

[0114] In addition, in the invention related to the positioning of the housing, although the engaging protrusion and the inner positioning groove are provided on the right side in the above-mentioned manner, they may be provided on the left side, or on both the left and right sides. They may also be provided at locations other than the left and right sides. The specific shapes of the protrusion and the groove may also be changed. The relationship between the protrusion and the groove may also be reversed.

[0115] In addition, as the inner positioning portion, although an inner positioning protrusion engaging with the slit of the inner shell is also used, the specific shape can be changed in this case, for example, it can be formed into a recess instead of a slit, etc. However, the inner positioning portion composed of the slit and the inner positioning protrusion can be omitted.

[0116] In addition, for the external positioning portion, the number and arrangement of the external positioning protrusions and the receiving recesses can be appropriately changed. The relationship between the protrusions and the recesses can also be reversed.

[0117] In addition, the connecting shaft may be formed integrally with the bearing holding portion, rather than being a separate component from the inner housing as in the above-mentioned connecting rod. The direction of the connecting shaft is not limited to the up-down direction.

[0118] In addition, the shape of the cylindrical rubber can be appropriately changed for the elastic body, and the cylindrical rubber can be divided or other elastic bodies can be added.

[0119] Fig.12 and Fig.13 Another modified example of the positioning structure of the outer case 2 and the inner case 3 is shown.

[0120] On the left and right side surfaces of the cylindrical rubber 74, three cutouts 100A to 100C are formed at predetermined intervals along the circumferential direction from the rear end toward the front. On the left and right outer surfaces of the inner housing 3, inner protrusions 101, 101 for locking with the central cutouts 100B, 100B are formed. On the left and right inner surfaces of the outer housing 2, a pair of upper and lower outer protrusions 102, 102 for locking with the upper and lower cutouts 100A, 100C are formed respectively. In addition, the fitting protrusion 36 and the inner positioning groove 79 are arranged on the left side, and the inner protrusion 101 on the left side is formed on the outer surface of the fitting protrusion 36.

[0121] According to this, in the assembled state, the inner protrusions 101, 101 are locked in the left and right cutouts 100B, 100B of the cylindrical rubber 74, thereby positioning the inner housing 3. In addition, the outer protrusions 102, 102 are respectively locked in the left and right cutouts 100A, 100C of the cylindrical rubber 74, thereby positioning the outer housing 2. In this positioned state, the cylindrical rubber 74 is sandwiched between the inner protrusions 101 and the outer protrusions 102, 102 in the circumferential direction of the cylindrical rubber 74.

[0122] Thus, in this modification example, the inner positioning portion is provided as the cutout 100B (inner stopped portion) for locking the inner protrusion 101 protruding outward from the inner shell 3, and the outer positioning portion is provided as the cutouts 100A, 100C (outer stopped portion) for locking the outer protrusions 102, 102 protruding inward from the inner surface of the outer shell 2, and the inner protrusion 101 and the outer protrusion 102 form a structure for clamping the cylindrical rubber 74 in the circumferential direction of the cylindrical rubber 74.

[0123] Thus, the relative shaking of the outer housing 2 and the inner housing 3 in the circumferential direction of the cylindrical rubber 74 is restricted, so that positioning with high reliability can be performed. In addition, since no protrusion such as the outer positioning protrusion is provided on the cylindrical rubber 74 as in the above-mentioned method, it is also possible to prevent the durability and positioning function of the cylindrical rubber 74 from being reduced due to damage to the protrusion.

[0124] Furthermore, the inner and outer locked portions are not limited to cutouts, and may be formed as through holes or recesses. The shapes and numbers of the inner and outer protrusions may also be changed.

[0125] In addition, in the present invention, the handle mounting portion is not necessarily arranged on the outer shell. Even if the handle mounting portion is arranged on the gear housing as in the prior art, a certain vibration reduction effect can be achieved by the elastic retention of the inner shell.

[0126] In addition, the outer shell may not be a split structure as in the above-mentioned embodiment, but may be a cylindrical body that is integrated with the inner shell. On the contrary, the inner shell may be formed of a plurality of parts, for example, in a split structure.

[0127] (Effects of the invention in which the acceleration sensor is elastically supported in the tool body)

[0128] The grinding machine 1 of the above-mentioned embodiment includes a tool body 1a and a spindle 6, wherein the tool body 1a is used to accommodate the brushless motor 4; the spindle 6 is rotated by the drive of the brushless motor 4 and is mounted with a top tool 97. In addition, the grinding machine 1 includes an acceleration sensor 23 and a controller 20, wherein the acceleration sensor 23 is provided in the tool body 1a; the controller 20 monitors the acceleration detected by the acceleration sensor 23 and controls the drive of the brushless motor 4. Moreover, the acceleration sensor 23 is elastically supported in the tool body 1a.

[0129] According to this structure, the acceleration due to the vibration generated during normal use will not be erroneously detected, and the acceleration due to the recoil or shaking will not be accurately determined. In addition, the possibility of the acceleration sensor 23 itself failing or being damaged due to vibration can be reduced. Accordingly, the acceleration sensor 23 can detect the phenomenon of recoil and shaking with high accuracy, thereby achieving excellent reliability. In addition, the durability of the acceleration sensor 23 can be ensured.

[0130] In particular, the tool body 1a includes an inner housing 3 (drive side housing) and an outer housing 2 (vibration-proof side housing), wherein the inner housing 3 is used to accommodate the brushless motor 4; the outer housing 2 elastically holds the inner housing 3, and the acceleration sensor 23 is arranged in the outer housing 2. Accordingly, the vibration reduction effect on the acceleration sensor 23 can be effectively obtained.

[0131] In addition, the outer housing 2 holds the inner housing 3 at the front side, and the acceleration sensor 23 is arranged at a position behind the inner housing 3. According to this, the acceleration sensor 23 can be arranged at a position away from the vibration source, thereby effectively reducing vibration.

[0132] In addition, the outer shell 2 has a rear cylinder 8 (handle), and the rear cylinder 8 has a switch lever 16 (operating member) for driving the brushless motor 4, and the acceleration sensor 23 is arranged at a position farther from the rear cylinder 8. According to this, the acceleration sensor 23 can be arranged at a position farther from the vibration source. In particular, since the heavy battery pack 11 is arranged at the rear end of the outer shell 2, the acceleration sensor 23 is brought close to the battery pack 11 to effectively reduce vibration.

[0133] In addition, the controller 20 is provided in the outer casing 2, and the acceleration sensor 23 is arranged in the controller 20. According to this, the acceleration sensor 23 can be easily arranged on the vibration-proof side together with the controller 20.

[0134] In the invention related to elastic support of the acceleration sensor, the configuration of the acceleration sensor is not limited to the above-mentioned method. For example, the acceleration sensor may not be directly mounted on the control circuit board, but the acceleration sensor and the control circuit board may be connected by wires away from the controller.

[0135] In addition, the acceleration sensor is not limited to being arranged in the battery mounting portion, and may also be arranged in the rear tube portion or the front tube portion.

[0136] In addition, the acceleration sensor may be arranged in a region of the outer housing that overlaps with the inner housing. In this case, the acceleration sensor may be elastically supported by a cylindrical rubber.

[0137] Furthermore, the present invention can be applied to a grinding machine without a vibration-proof structure. In this case, only the acceleration sensor or the controller including the acceleration sensor can be elastically supported in the tool body by an elastic body such as rubber.

[0138] Furthermore, by arranging the second acceleration sensor on the driving side housing, the controller can monitor the difference between the accelerations detected by the acceleration sensor on the vibration-proof side housing and the second acceleration sensor, and compare the difference with a threshold value, thereby controlling the driving of the motor.

[0139] (Effect of the invention related to the rectifying portion divided into two radially inner and outer portions)

[0140] The grinding machine 1 of the above-mentioned method includes an inner housing 3 (housing) and a centrifugal fan 66 (fan), wherein the inner housing 3 is used to accommodate the brushless motor 4 (motor); the centrifugal fan 66 rotates as the brushless motor 4 is driven, thereby generating cooling wind for the brushless motor 4 in the inner housing 3. In addition, the grinding machine 1 includes a cone 30, an expansion portion 31 (cylindrical portion) and a rectifying portion 67, wherein the cone 30 and the expansion portion 31 are formed in the inner housing 3 and are used to accommodate the centrifugal fan 66; the rectifying portion 67 is opposite to the centrifugal fan 66 and is arranged on the upstream side of the cooling wind. Moreover, the rectifying portion 67 is divided into two parts, an inner part and an outer part, in the radial direction of the cone 30 and the expansion portion 31, and the radial outer side is formed by the cone 30, and the radial inner side is formed by the baffle 55 assembled to the inner housing 3.

[0141] According to this structure, the rectifying portion 67 can be formed by using a part of the inner housing 3 and the baffle 55, without increasing the axial length of the inner housing 3 or generating a useless space.

[0142] In particular, the baffle plate 55 has a front pressing portion 57 (contact portion) that contacts the stator 40 in the axial direction of the stator 40 of the brushless motor 4. Thus, the baffle plate 55 can be used to position the stator 40.

[0143] In addition, the baffle plate 55 is screwed to the inner housing 3, so that the stator 40 is fixed by the front pressing portion 57. According to this, the stator 40 can be fixed while the baffle plate 55 is fixed.

[0144] The rectifying portion 67 is provided with a through hole 68 (screw passage) for passing the screw 58 for screw-fastening the baffle 55. This allows the screw 58 to be disposed close to the inner housing 3 and the stator 40, thereby maintaining the compactness of the inner housing 3.

[0145] In addition, the screw passage portion is formed as the through hole 68 formed so as to straddle the tapered portion 30 and the baffle plate 55. According to this, the screw passage portion can be formed without significantly changing the shape of the rectifying portion 67.

[0146] In addition, an inner positioning protrusion 77 (spacer) is provided in a detachable manner relative to the inner housing 3, and the inner positioning protrusion 77 blocks the through hole 68 after the baffle 55 is screwed and fastened to form a continuous surface between the tapered portion 30 and the baffle 55. Therefore, even if the through hole 68 is provided, the function of the rectifying portion 67 will not be reduced.

[0147] In addition, the outer housing 2 is provided on the outer side of the inner housing 3 and connected via the cylindrical rubber 74 (elastic body), and the inner positioning protrusion 77 is formed as a part of the cylindrical rubber 74. Thus, the inner positioning protrusion 77 and the cylindrical rubber 74 can be easily assembled together.

[0148] In addition, the inner positioning protrusion 77 positions the inner housing 3 with respect to the cylindrical rubber 74. According to this, the inner housing 3 can be easily positioned by the cylindrical rubber 74.

[0149] In the invention related to the rectifying part, the number and position of the screws for threading the baffle are not limited to the above-mentioned method. The baffle may be threadedly fastened from the rear instead of from the front. The baffle may also be threadedly fastened along the radial direction.

[0150] In addition, the screw passage portion may not be provided in a manner spanning the tapered portion and the baffle of the inner housing, but may be provided only on one side. The spacer may not also serve as the positioning member of the inner housing, but may block the screw passage portion independently of an elastic body such as a cylindrical rubber.

[0151] In addition, the baffle is not limited to being fastened with threads, and a structure without using screws may be adopted, such as a structure in which an integrally formed locking piece is locked and fixed to the inner housing.

[0152] In addition, the present invention is not limited to grinders, and can also be applied to angle drills, reciprocating saws, circular saws, etc. as long as the electric tool has a fan and a rectifier in the cylindrical part of the housing. Accordingly, it is not limited to electric tools having an outer housing and an inner housing. The fan can also be provided on other shafts that transmit rotation from the output shaft, rather than the output shaft of the motor.

[0153] In addition, the inventions are the same, and other structures of the grinder are not limited to the above-mentioned methods. For example, the motor is not limited to a brushless motor. In addition, multiple battery packs (batteries) can also be used as power sources. In addition, it can also be an AC tool that does not use batteries.

Claims

1. An electric tool, characterized in that: It includes a housing, a fan, a cylindrical portion and a rectifying portion, wherein: The housing is used to accommodate the motor; The fan rotates as the motor is driven, thereby generating cooling wind for the motor in the housing; The cylindrical portion is formed on the housing and is used to accommodate the fan at the front, and the axis of the cylindrical portion extends in the front-rear direction; The rectifying portion is disposed on the upstream side of the cooling air so as to face the fan. The rectifying portion is divided into two parts, an inner part and an outer part, in the radial direction of the cylindrical portion. The radial outer side is formed by the cylindrical portion, and the radial inner side is formed by a baffle assembled to the housing. The whole has a shape that expands toward the front.

2. The electric tool according to claim 1, characterized in that: The baffle has an abutment portion that abuts against the stator of the motor in an axial direction thereof.

3. The electric tool according to claim 2, characterized in that: The baffle is screwed to the housing, thereby fixing the stator via the abutment portion.

4. The electric tool according to claim 3, characterized in that: The rectifying portion is provided with a screw passing portion for passing a screw, and the screw is used for threadingly fastening the baffle.

5. The electric tool according to claim 4, characterized in that: The screw passage portion is a through hole formed across the cylindrical portion and the baffle.

6. The electric tool according to claim 4 or 5, characterized in that: A spacer is provided in a detachable manner with respect to the housing, and forms a continuous surface between the cylindrical portion and the baffle plate by blocking the screw passing portion after the baffle plate is screwed.

7. The electric tool according to claim 6, characterized in that: An outer shell is provided on the outer side of the shell and connected with the outer shell by an elastic body, and the spacer is formed as a part of the elastic body.

8. The electric tool according to claim 7, characterized in that: The spacer positions the housing relative to the elastic body.

9. The electric tool according to claim 4 or 5, characterized in that: The screw passes through the screw passing portion in parallel with the axis of the housing, penetrates the baffle, and is screwed into the housing.

10. The electric tool according to claim 9, characterized in that: The screw and the screw passage are provided in a pair at point-symmetrical positions with respect to the axis.

11. The electric tool according to claim 7, characterized in that: The elastic body is annular.

12. The electric tool according to claim 7, characterized in that: The outer shell is divided into a pair of split shells.

13. The electric tool according to claim 12, characterized in that: The housing is rotatably connected to the outer housing via a connection shaft extending in a predetermined direction.

14. The electric tool according to claim 13, characterized in that: The connecting shaft penetrates the housing, and both ends thereof are held by the outer housing via a second elastic body.

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