Grinding tools

Abstract

To facilitate wiring between a detection mechanism of an auxiliary handle and a controller.SOLUTION: A grinder 1 comprises: a housing 2 which accommodates a motor 6 and extends in a longitudinal direction; a spindle which protrudes from a front part of the housing 2 and is rotated by driving of a motor 6 where a tip tool can be attached to an end part of the protrusion; a controller which controls driving of the motor 6; a handle attachment part installed at a front part of the housing 2 and to which a side handle can be detachably attached; and a handle detection mechanism which electrically detects fitting status of the side handle to the handle attachment part. The housing 2 includes a cylindrical inner housing 3 which accommodates the motor 6, and a cylindrical outer housing 5 which covers an outer side of the inner housing 3 and extends in a rear side relative to the inner housing 3, in which first and second wirings 90 electrically connecting the controller with the handle detection mechanism are passed between the inner housing 3 and the outer housing 5.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to grinding tools such as grinders. Note that "grinding" in the present disclosure is a concept that also includes "polishing".

Background Art

[0002] A grinder, which is an example of a grinding tool, has a spindle protruding downward from the front part of a housing that houses a motor and extends in the front-rear direction, and a tip tool such as a disk-shaped grindstone is attached to the lower end of the spindle. Therefore, it is possible to polish a workpiece with the tip tool that rotates together with the spindle. As disclosed in Patent Document 1, in the grinder, the rear part of the housing that extends in the front-rear direction serves as the main handle, and a side handle (auxiliary handle) can be attached to either the left or right side of the front side surface of the housing. The operator operates the grinder by gripping the rear part of the housing with one hand and the side handle with the other hand. In this grinder, in order to prevent the occurrence of kickback in which the grinder is swung around by the reaction force received by the tip tool from the workpiece, a handle detection mechanism that electrically detects the attachment of the auxiliary handle is provided. When the controller does not obtain a detection signal from the handle detection mechanism, it does not drive the motor even if the switch is turned on.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The controller is sometimes positioned behind the motor within the housing. In this case, wiring must be routed between the auxiliary handle mounting point at the front of the housing and the controller at the rear of the housing, making it difficult to route the wiring while avoiding the motor and fan.

[0005] Therefore, the purpose of this disclosure is to provide a grinding tool that allows for easy wiring between the auxiliary handle detection mechanism and the controller. [Means for solving the problem]

[0006] To achieve the above objective, this disclosure provides a grinding tool comprising a housing that houses a motor and extends in the front-rear direction, A spindle that protrudes from the front of the housing and rotates under the drive of a motor, with a tip tool that can be attached to the protruding end, A controller that controls the motor's operation, A handle mounting section is provided at the front of the housing, from which an auxiliary handle can be attached and detached. It includes a handle detection mechanism that electrically detects the mounting status of the auxiliary handle to the handle mounting section. Furthermore, the housing comprises at least a cylindrical inner housing that houses the motor, and a cylindrical outer housing that covers the outside of the inner housing and extends further back than the inner housing. The controller is housed in the outer housing behind the motor, and the handle mounting section and handle detection mechanism are provided in multiple locations at the front of the outer housing. The wiring that electrically connects the controller and each steering wheel detection mechanism consists of a first wire that connects each steering wheel detection mechanism to each other between the inner housing and the outer housing, and a second wire that is connected to the first wire, runs through the space between the inner housing and the outer housing into the outer housing, and connects to the controller. Consists of It is characterized by the following: To achieve the above objective, another configuration of the present disclosure is a grinding tool comprising a housing that houses a motor and extends in the front-rear direction, A spindle that protrudes from the front of the housing and rotates under the drive of a motor, with a tip tool that can be attached to the protruding end, A controller that controls the motor's operation, A handle mounting section is provided at the front of the housing, from which an auxiliary handle can be attached and detached. It includes a handle detection mechanism that electrically detects the mounting status of the auxiliary handle to the handle mounting section. Furthermore, the housing comprises at least a cylindrical inner housing that houses the motor, and a cylindrical outer housing that covers the outside of the inner housing and extends further back than the inner housing. The controller is housed in the outer housing behind the motor, and the handle mounting section and handle detection mechanism are provided in multiple locations at the front of the outer housing. Each steering wheel detection mechanism is electrically connected to the controller by separate wiring that runs from each steering wheel detection mechanism through the inner housing and the outer housing into the outer housing. [Effects of the Invention]

[0007] According to this disclosure, wiring between the handle detection mechanism and the controller can be easily performed while avoiding motors and other components. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a grinder. [Figure 2] This is a plan view of the grinder. [Figure 3] This is a left side view of the grinder. [Figure 4] This is a cross-sectional view along line AA in Figure 2. [Figure 5] Figure 2 is an enlarged cross-sectional view of the BB line. [Figure 6] Figure 2 is an enlarged cross-sectional view along the CC line. [Figure 7] Figure 3 is a cross-sectional view along the DD line. [Figure 8]Exploded perspective view of the handle attachment part and the handle detection mechanism as seen from the left side. [Figure 9] Exploded perspective view of the handle detection mechanism as seen from the right side. [Figure 10] Perspective view of the left half housing. [Figure 11] Perspective view from below of a grinder with the outer housing omitted. [Figure 12] Bottom view of a grinder with the outer housing omitted. [Figure 13] Bottom view of a grinder showing a modified example of wiring with the outer housing omitted.

Mode for Carrying Out the Invention

[0009] In one embodiment of the present disclosure, the outer housing is made of resin, and the handle attachment part may be provided integrally with the outer housing. According to this configuration, it becomes difficult for vibrations such as those of a motor to be transmitted to the side handle. In one embodiment of the present disclosure, a plurality of handle attachment parts are provided, and the handle detection mechanisms of each handle attachment part are connected to each other by a first wiring, and one second wiring connected to the first wiring may be connected to a controller. According to this configuration, the wiring between the controller and the handle detection mechanism can be simplified. In one embodiment of the present disclosure, the inner housing may be held in the outer housing via an elastic member. According to this configuration, the vibration transmitted from the inner housing to the outer housing is reduced, and the feeling of use of the operator holding the outer housing is not deteriorated. In one embodiment of the present disclosure, a wiring guide part may be provided on the outer surface of the inner housing and / or the inner surface of the outer housing. According to this configuration, the routing of the wiring passing between the inner housing and the outer housing becomes easy.

Examples

[0010] The embodiments of this disclosure will be described below with reference to the drawings. Figure 1 is a perspective view showing a grinder, an example of a grinding tool. Figure 2 is a plan view of the grinder. Figure 3 is a left side view of the grinder. Figure 4 is a cross-sectional view taken along line AA in Figure 2. The housing 2 of the grinder 1 extends in the front-to-back direction. The housing 2 has an inner housing 3, a gear housing 4, and an outer housing 5. The inner housing 3 and outer housing 5 are made of resin, while the gear housing 4 is made of metal. The inner housing 3 is cylindrical and houses the motor 6 (a commutator motor in this case). The motor 6 is held inside the inner housing 3 with its output shaft 7 facing in the front-to-back direction. The gear housing 4 is bolted to the inner housing 3 from the front via a gear housing cover 8. Multiple exhaust ports 9, 9·· are formed on the front of the gear housing 4, communicating with the inside of the inner housing 3. The front of the output shaft 7 protrudes into the gear housing 4 through the gear housing cover 8. The gear housing cover 8 is provided with a bearing 10 that supports the output shaft 7. A fan 11 is fixed to the output shaft 7 behind the gear housing cover 8.

[0011] A bevel gear 12 is provided at the front end of the output shaft 7 within the gear housing 4. A bearing box 13 is assembled to the lower part of the gear housing 4. A spindle 14 is provided in the vertical direction inside the gear housing 4 and the bearing box 13. The spindle 14 has a bevel gear 15 at its upper part. The bevel gear 15 meshes with the bevel gear 12 of the output shaft 7. The spindle 14 is supported by upper and lower bearings 16, 16 held within the gear housing 4 and the bearing box 13. The lower end of the spindle 14 protrudes downward from the bearing box 13. A cutting tool 19 (e.g., a disc-shaped grinding wheel) can be attached to the lower end of the spindle 14 by an inner flange 17 and a lock nut 18. A wheel cover 20 is attached to the bearing box 13 to cover the rear upper and rear sides of the cutting tool 19.

[0012] The outer housing 5 is cylindrical and consists of a pair of left and right split housings 5a and 5b fastened together with screws from the left and right directions. The outer housing 5 has a front main body portion 25 and a rear main grip portion 26. Multiple air intake ports 27, 27... are formed on the left and right sides of the rear of the main body portion 25. The main grip portion 26 has a smaller diameter than the main body portion 25 and extends rearward from a position eccentrically upward from the axis of the main body portion 25, sloping downward. The main grip portion 26 is equipped with a switch 28 and a switch lever 29. The switch lever 29 can swing up and down with its rear end as a pivot point, and the switch 28 is turned ON by an upward pushing operation. A power cord 30 is connected to the rear end of the main grip portion 26. The front of the main body 25 coaxially holds the inner housing 3 via a rubber sleeve 31. A metal fixing ring 32, which is externally mounted on the rubber sleeve 31, is provided on the front side of the main body 25. The outer housing 5 is connected to the fixing ring 32 by a protruding portion 63, which will be described later, being screwed to the fixing ring 32.

[0013] A bearing retaining portion 33 is integrally formed at the rear of the inner housing 3. The output shaft 7, which protrudes rearward from the commutator, is supported by a bearing 34 held in the bearing retaining portion 33. A pair of support protrusions 35, 35 are provided above and below the bearing retaining portion 33. The support protrusions 35, 35 are arranged coaxially in the vertical direction perpendicular to the axis of the output shaft 7. Each support protrusion 35 is fitted with a rubber cap 36. On the inner surfaces of the left and right split housings 5a, 5b, as shown in Figure 10, retaining portions 37, 37 are provided above and below, protruding towards the center in the left-right direction and holding the upper and lower rubber caps 36, 36 in the center. Thus, the inner housing 3 is elastically supported within the outer housing 5 via the front rubber sleeve 31 and the rear rubber caps 36, 36. In this state, a cylindrical space S is formed around the entire circumference between the inner housing 3 and the outer housing 5, as shown in Figure 6.

[0014] The rear end of the output shaft 7 extends rearward through the bearing holder 33. A brake drum 38 is fixed to the rear end of the output shaft 7. As shown in Figure 7, a pair of brake arms 39, 39 are provided on both the left and right sides of the brake drum 38 within the main body 25. The brake arms 39, 39 are supported so as to be able to swing from side to side with their upper ends as a pivot point. The brake arms 39, 39 are biased toward the brake drum 38 by having brake shoes 40, 40 that face the outer circumferential surface of the brake drum 38. The brake arms 39, 39 are linked to the swing of the switch lever 29 by a linkage mechanism 41. At the lower limit position of the switch lever 29, when the switch 28 is in the OFF position, the brake drum 38 is pressed against the brake shoes 40, 40 of the brake arms 39, 39. Therefore, the rotation of the brake drum 38 and the output shaft 7 is restricted. When the switch lever 29 is pushed upward from this position to turn the switch 28 ON, the brake arms 39, 39 expand via the linkage mechanism 41, releasing the pressure on the brake drum 38 by the brake shoes 40, 40. Therefore, the rotation of the brake drum 38 and the output shaft 7 is permitted.

[0015] A controller 42 is located inside the main body 25 behind the brake drum 38. The controller 42 is held vertically in the center in the left-right direction. The controller 42 has a control circuit board 43 inside which a microcontroller, memory, etc., are mounted. An adjustment dial 44 is provided on the upper front side of the control circuit board 43. As shown in Figures 1 to 4, the upper part of the adjustment dial 44 is exposed above the outer housing 5. The rotation speed of the motor 6 can be adjusted by rotating the adjustment dial 44.

[0016] On the front left and right sides of the housing 2, there are handle mounting sections 45 from which the side handle 50 can be attached and detached, and a handle detection mechanism (hereinafter referred to as the "detection mechanism") 46 that detects the mounting status of the side handle 50 to the handle mounting section 45. The details are described below. However, since the handle mounting section 45 and the detection mechanism 46 are symmetrical, the left-side handle mounting section 45 and detection mechanism 46 will be described mainly. Figure 8 is an exploded perspective view of the mounting section and detection mechanism from the left side. Figure 9 is an exploded perspective view of the detection mechanism from the right side. First, as shown in Figure 5, the side handle 50 comprises a grip portion 51 and a bolt 52. The grip portion 51 extends in a straight line and has a flange 53 at its end. The bolt 52 is held at the center of the grip portion 51, with a threaded portion 54 protruding from the center of the flange 53. At the center of the flange 53, a boss portion 55 is formed, covering the periphery except for the tip of the threaded portion 54. A contact plate 56 is fixed around the boss portion 55. The contact plate 56 is disc-shaped, coaxially surrounding the boss portion 55, and its end face is formed at a lower position than the end face of the boss portion 55 (closer to the flange 53), exposing the tip of the boss portion 55.

[0017] Receiving surfaces 60 are formed on the left and right sides of the fixing ring 32. The receiving surfaces 60 are defined in the front-to-back and up-to-down directions and are planes that extend in the up-to-down direction. A handle mounting portion 45 is projected from the center of the receiving surface 60 in the up-to-down direction. The handle mounting portion 45 is cylindrical in shape and protrudes to the left. A first screw hole 61 is formed in the left-to-right direction at the center of the handle mounting portion 45, passing through the fixing ring 32 in the radial direction. The side handle 50 is attached coaxially to the handle mounting portion 45 by screwing the threaded portion 54 of the side handle 50 into the first screw hole 61. As shown in Figure 5, the threaded portion 54 can be screwed in until the end face of the boss portion 55 abuts against the end face of the handle mounting portion 45. On the receiving surface 60, two second screw holes 62, 62, which have a smaller diameter than the first screw hole 61, are formed above and below the first screw hole 61, parallel to the first screw hole 61. Here, a rubber sleeve 31 is positioned inside the metal fixing ring 32, thereby providing insulation between the side handle 50, which is attached to the handle mounting section 45, and the motor 6 and other components inside.

[0018] The front end of the outer housing 5 is provided with a pair of left and right protruding portions 63. The protruding portions 63 extend outward from the front end of the outer housing 5 to the left and right, and then are plate-shaped and protrude forward on the left and right outer sides of the receiving surfaces 60, 60 of the fixing ring 32. The front part of the protruding portion 63 is semicircular in side view. A cylindrical portion 64 is formed in the protruding portion 63 and penetrates it in the left-right direction. The cylindrical portion 64 is located at the center of the semicircle. The left end of the cylindrical portion 64 is fitted with the boss portion 55 of the side handle 50. On the left side of the protruding portion 63, a circular receiving recess 65 is formed concentrically with the cylindrical portion 64 when viewed from the side. Above and below the cylindrical portion 64, small cylindrical portions 66, 66 are formed in the receiving recess 65, which penetrate the protruding portion 63 in the left-right direction. The small cylindrical portions 66, 66 are coaxially located to the left outer side of the second screw holes 62, 62 provided in the receiving surface 60 of the fixing ring 32. Behind the cylindrical portion 64, three ribs 67, 67... are formed on the outer circumference of the receiving recess 65. Each rib 67 is formed in an arc shape, spaced apart in the circumferential direction on a concentric circle centered on the cylindrical portion 64. Notches 68 are formed at two locations, top and bottom, on the front of the protruding portion 63, and at the center in the vertical direction on the rear of the protruding portion 63. Outside the ribs 67, a pull-out hole 69 is formed on the lower rear side of the protruding portion 63, which penetrates in the left-right direction.

[0019] The detection mechanism 46 is provided on the protruding portion 63. The detection mechanism 46 comprises a pressure sensor 70, a pressing rubber 71, a movable plate 72, and an outer cover 73. The pressure sensor 70 is a sheet-like material whose resistance changes depending on the load in the thickness direction. The pressure sensor 70 has a ring shape in side view, with a cylindrical portion 64 passing through its center and positioned on the bottom surface of the receiving recess 65. Notches 74, 74 are formed on the upper and lower outer circumference of the pressure sensor 70 to avoid interference with the small cylindrical portions 66, 66. The pressure sensor 70 has a first wiring 90 that is routed from inside the outer housing 5 through a routing hole 69 to the left outer side of the protruding portion 63. but They are electrically connected.

[0020] The pressure rubber 71 overlaps the pressure sensor 70 from the left side inside the rib 67. The pressure rubber 71 is disc-shaped and penetrates the cylindrical portion 64. Three protrusions 75, 75... are formed on the outer circumference of the pressure rubber 71, which engage with the notches 68, 68... of the protruding portion 63 from the inside. Semicircular inner relief portions 76, 76 are formed on the upper and lower outer circumferences of the pressure rubber 71 to avoid interference with the small cylindrical portions 66, 66. On the left side of the pressure rubber 71, recesses 77, 77... are formed radially inward from the protrusions 75, 75... The recesses 77, 77... are arranged at equal intervals in the circumferential direction of the pressure rubber 71. On the right side of the pressure rubber 71, convex portions 78, 78... are formed, located on the back side of the recesses 77, 77... The movable plate 72 is positioned inside the rib 67 and to the left outside of the pressure rubber 71. The movable plate 72 is disc-shaped and penetrates the cylindrical portion 64. Semicircular relief portions 79, 79 are formed on the upper and lower outer circumferences of the movable plate 72 to avoid interference with the small cylindrical portions 66, 66. Inner pins 80, 80... and outer pins 81, 81... are provided coaxially on both the left and right sides of the movable plate 72. The inner pins 80 and outer pins 81 are arranged at equal intervals in the circumferential direction. The inner pins 80, 80... are located outside the recesses 77, 77... of the pressure rubber 71, respectively.

[0021] The outer cover 73 has the same shape as the protruding portion 63 when viewed from the side. Locking protrusions 82, 82, corresponding to the notches 68, 68, 63 of the protruding portion 63 are formed on the right side of the front and rear ends of the outer cover 73. A round hole 83 is formed in the front of the outer cover 73, coaxial with the left side of the cylindrical portion 64 of the protruding portion 63. The boss portion 55 of the side handle 50 can pass through the round hole 83. A pair of receiving seats 84, 84 are recessed above and below the round hole 83. Each receiving seat 84 has a through hole 85. Each through hole 85 is coaxially positioned to the left of the small cylindrical portion 66 of the protruding portion 63. The outer cover 73 has three small holes 86, 86, 63, through which the outer pins 81, 81, 63 of the movable plate 72 pass.

[0022] The detection mechanism 46 sets the pressure sensor 70, the pressure rubber 71, and the movable plate 72 in order in the receiving recess 65. Then, the outer cover 73 is placed over it from the outermost side, and two screws 87, 87 are driven from the left outer side through the through holes 85, 85 and the small cylindrical parts 66, 66 of the protruding part 63 and screwed into the second screw holes 62, 62 of the receiving surface 60. As a result, the handle mounting part 45 is integrally fixed to the protruding part 63 of the outer housing 5. The pressure sensor 70 is prevented from rotating at the bottom surface of the receiving recess 65 by the engagement of the small cylindrical portion 66 and the notch 74. The pressing rubber 71 is prevented from rotating within the receiving recess 65 by the engagement of the small cylindrical portion 66 and the inner relief portion 76, and by the engagement of the protrusion 75 and the notch 68, causing the protrusion 78 to contact the pressure sensor 70. The movable plate 72 is housed so as to be movable in the left-right direction between the pressing rubber 71 and the outer cover 73. However, with each inner pin 80 in contact with each recess 77 of the pressing rubber 71, the movable plate 72 is biased by the elasticity of the pressing rubber 71 to the outermost position, with each outer pin 81 protruding outward from each small hole 86 of the outer cover 73, as shown in the detection mechanism 46 on the right side of Figure 7.

[0023] The pressure sensor 70 is electrically connected to the control circuit board 43 of the controller 42. As shown in Figures 11 and 12, the left and right pressure sensors 70 are electrically connected to each other by a first wiring 90 consisting of multiple signal lines. A second wiring 91, also consisting of multiple signal lines, is electrically connected to the first wiring 90. The second wiring 91 is connected to the control circuit board 43. The first wiring 90 and the second wiring 91 are routed within the cylindrical space S between the inner housing 3 and the outer housing 5. First, within the cylindrical space S, a pair of parallel first protrusions 92, 92 are provided on the front inner surface of the left half-housing 5a, as shown in Figures 6 and 10. The first protrusions 92, 92 extend circumferentially around the half-housing 5a, with their upper ends behind the pull-out holes 69 of the left overhang 63, and reach the lower end of the half-housing 5a.

[0024] A pair of parallel second protrusions 93, 93 are provided on the inner surface of the split housing 5a. The second protrusions 93, 93 rise circumferentially from near the lower inner surface of the split housing 5a in front of the holding portion 37 of the rubber cap 36, then extend forward along the axial direction, and connect to the upper end of the first protrusions 92, 92 behind the pull-out hole 69 of the left overhang portion 63. Each protrusion 92, 93 is provided with a plurality of projections 94, 94... that protrude toward each other at predetermined intervals in the extension direction, and are located opposite each other. Furthermore, a guide groove 95 is formed on the lower right side of the rear of the rubber sleeve 31, which is initially formed in a sloping manner from the central rear end in the left-right direction toward the front right, and then extends to the right along the circumferential direction.

[0025] Both ends of the first wiring 90 pass through the exit holes 69 of the left and right protruding portions 63, respectively, and are pulled out to the left and right outer sides of the protruding portions 63, and are electrically connected to the pressure sensor 70 in the receiving recess 65. In the cylindrical space S, the middle portion of the first wiring 90 is held on the right side by fitting into the guide groove 95 of the rubber sleeve 31, and on the left side is held between the first protrusions 92, 92 of the split housing 5a. The second wiring 91, which is drawn out from the control circuit board 43, is held between the second protrusions 93, 93 within the cylindrical space S and is routed forward along the second protrusions 93, 93. The second wiring 91 is then connected to the first wiring 90 behind the left-side exit hole 69.

[0026] In the grinder 1 configured as described above, when power is supplied from the power cord 30, the microcontroller on the control circuit board 43 constantly monitors the resistance values ​​(load detection signals) of the pressure sensors 70, 70 in the left and right detection mechanisms 46, 46 via the first wiring 90 and the second wiring 91, and compares them with a predetermined threshold. When neither the left nor right handle mounting section 45, 45 has a side handle 50 attached, the resistance values ​​of the pressure sensors 70, 70 do not exceed the threshold. Therefore, even if the switch lever 29 is pressed and the switch 28 is turned ON in this state, the microcontroller does not drive the motor 6. On the other hand, when the threaded portion 54 of the side handle 50 is screwed into either the left or right handle mounting portion 45, 45, the boss portion 55 comes into contact with the handle mounting portion 45. In this state, a gap smaller than the amount of protrusion of the outer pins 81 from the outer cover 73 is formed between the left and right sides of the outer cover 73 and the end face of the contact plate 56 of the side handle 50. As a result, each outer pin 81 that is in contact with the end face of the contact plate 56 is pressed, and the movable plate 72 moves inward to the left and right.

[0027] Then, each inner pin 80 of the movable plate 72 presses against each recess 77 of the pressure rubber 71. As a result, each protrusion 78 on the back side of each recess 77 presses against the pressure sensor 70. When the pressure sensor 70 is pressed, the resistance value changes and is input to the control circuit board 43 as a load detection signal. When the microcontroller confirms that the input resistance value exceeds a threshold, it determines that the side handle 50 has been attached. In this state, the switch lever 29 is pushed in to turn on the switch 28. The microcontroller then supplies power to the motor 6. As mentioned above, the brake on the brake drum 38 is released when the switch lever 29 is pushed in, so the output shaft 7 rotates together with the brake drum 38. The rotation of the output shaft 7 is transmitted to the spindle 14 via the bevel gears 12 and 15. As a result, the tip tool 19 rotates. The operator can hold the main grip portion 26 with one hand and the grip portion 51 of the side handle 50 with the other hand to perform grinding or other operations on the workpiece using the tip tool 19.

[0028] As described above, the grinder 1 of the above embodiment includes a housing 2 that houses a motor 6 and extends in the front-rear direction, a spindle 14 that protrudes from the front of the housing 2 and rotates when driven by the motor 6, and to which a tip tool can be attached at the protruding end, a controller 42 that controls the drive of the motor 6, a handle mounting part 45 provided at the front of the housing 2 to which a side handle 50 (an example of an auxiliary handle) can be attached and detached, and a detection mechanism 46 that electrically detects the mounting state of the side handle 50 to the handle mounting part 45. The housing 2 comprises at least a cylindrical inner housing 3 that houses the motor 6, and a cylindrical outer housing 5 that covers the outside of the inner housing 3 and extends rearward from the inner housing 3. First and second wirings 90 and 91 (an example of wiring) that electrically connect the controller 42 and the detection mechanism 46 are passed between the inner housing 3 and the outer housing 5. This configuration allows for easy wiring between the detection mechanism 46 and the controller 42, avoiding the motor 6 and fan 11.

[0029] The outer housing 5 is made of resin, and the handle mounting portion 45 is integrally provided with the outer housing 5. Therefore, vibrations from the motor 6 and other components are less likely to be transmitted to the side handle 50. Two handle mounting sections 45 are provided, and the detection mechanisms 46, 46 of each handle mounting section 45 are connected to each other by a first wiring 90, and a second wiring 91 connected to the first wiring 90 is connected to the controller 42. Therefore, the wiring between the controller 42 and the detection mechanism 46 can be simplified. The inner housing 3 is held within the outer housing 5 via a rubber sleeve 31 (an example of an elastic member). Therefore, vibrations transmitted from the inner housing 3 to the outer housing 5 are reduced, and the user experience of the operator gripping the main grip portion 26 is not diminished. On the inner surface of the outer housing 5, there are first and second protrusions 92 and 93 (an example of a guide section) that guide the first and second wirings 90 and 91. Therefore, routing the first and second wirings 90 and 91 between the inner housing 3 and the outer housing 5 becomes easier.

[0030] The following are examples of changes to this disclosure. In the above embodiment, the left and right pressure sensors are connected by a first wire, and the first wire is connected to the controller by a single second wire. The wiring configuration is not limited to this. For example, as shown in Figure 13, the first wires 90, 90 connected to the pressure sensors 70, 70 of the left and right detection mechanisms 46, 46, respectively, may be routed to the rear and connected to the controller 42. In this way, by connecting each detection mechanism 46 to the controller 42 with separate first wirings 90, if one of the wirings 90 is disconnected or otherwise damaged, the controller 42 can determine that both are not equipped with handlebars, even if there is no problem with the other wiring 90. In this case, the right-side split housing 5b may also be provided with a second projection 93, 93 to guide the wiring 90.

[0031] The wiring guide section is not limited to the protrusions in the above embodiment. The form and position of the protrusions can be changed as appropriate. The height of the protrusions may be changed, or they may be provided intermittently. The shape and position of the projections on the protrusions can also be changed. The projections may be omitted. The wiring guide is not limited to protrusions. For example, a guide groove may be provided on the inner surface of the outer housing. The wiring guide may be provided on the outer surface of the inner housing instead of the inner surface of the outer housing. Alternatively, guides may be provided on both the inner surface of the outer housing and the outer surface of the inner housing to guide the wiring. The wiring can be routed through the top or side of the cylindrical space, rather than the bottom. The space between the inner housing and the outer housing does not have to be cylindrical. A partially axial space may be formed, as long as wiring can be routed between the detection mechanism and the controller. In both the above embodiment and the modified example, a notification means may be provided to notify of an abnormality when the wiring is disconnected or otherwise damaged.

[0032] The detection mechanism is not limited to the above embodiment which employs a single sheet-shaped pressure sensor. For example, an independent pressure sensor may be provided for each inner pin of the movable plate. In this case, the attachment of the side handle may be determined when the resistance value of some (e.g., two) of the pressure sensors exceeds a threshold, rather than all of them. The number of inner pins and pressure sensors can be increased or decreased as appropriate. In the above embodiment, the attachment of the side handle is detected by a detection mechanism, but the detection mechanism may also detect the gripping of the grip portion. In this case, as mentioned above, multiple pressure sensors may be provided, and the gripping of the grip portion may be determined by the change in the resistance value of some of the pressure sensors in conjunction with the tilting of the side handle. However, the detection mechanism is not limited to one using a pressure sensor. For example, as disclosed in Patent Document 1 mentioned above, a mechanism using a detection plate whose position changes with the attachment of the side handle and a photointerrupter that detects the position of the detection plate may also be used. Other structures can also be adopted.

[0033] In the above embodiment, if the side handle is not attached, the controller is configured to prevent the motor from driving even when the switch is turned ON, but this is not limited to this configuration. For example, if the side handle is not attached, the controller may be configured to drive the motor by supplying a smaller-than-normal amount of drive power to the motor when the switch is turned ON. This is because the reaction force that the tip tool receives from the workpiece is reduced, making kickback less likely, and there is no problem in being able to work by gripping only the main grip. The handle mounting portion is not limited to being indirectly attached to the outer housing via a fixing ring, as in the above embodiment. The handle mounting portion can also be directly attached to the outer housing or gear housing. The auxiliary handle is not limited to the side handle of the above embodiment; the shape of the grip portion, etc., can be changed as appropriate. The auxiliary handle can also employ a connection structure other than screw-in.

[0034] The structure of the inner housing and outer housing is not limited to the above embodiment. For example, the outer housing does not have to be a split structure. The inner housing may also be a split structure. The elastic support of the inner housing by the outer housing is not limited to the above embodiment. For example, the length of the rubber sleeve may be changed, or multiple short rubber rings may be arranged in the axial direction. Elastic support can also be omitted. The grinder may be a DC tool using a battery pack, rather than an AC tool using commercial power. The motor may also be a brushless motor. The grinding tools described herein are not limited to grinders. For example, this disclosure is also applicable to other grinding and polishing tools such as polishers and sanders. Therefore, the handle mounting portion is not limited to a pair of left and right portions. The handle mounting portion may be only on the left or right side, or there may be three or more. [Explanation of Symbols]

[0035] 1. Grinder, 2. Housing, 3. Inner housing, 4. Gear housing, 5. Outer housing, 6. Motor, 7. Output shaft, 14. Spindle, 19. Tip tool, 25. Main body, 26. Main grip, 28. Switch, 29. Switch lever, 42. Controller, 43. Control circuit board, 45. Handle mounting section, 46. Handle detection mechanism, 50. Side handle, 51. Grip 52...Bolt, 54...Screw part, 60...Receiving surface, 61...First screw hole, 63...Protruding part, 65...Receiving recess, 69...Pull-out hole, 70...Pressure sensor, 71...Pressure rubber, 72...Movable plate, 73...Outer cover, 77...Recess, 78...Protrusion, 80...Inner pin, 81...Outer pin, 87...Screw, 90...First wiring, 91...Second wiring, 92...First protrusion, 93...Second protrusion, 95...Guide groove, S...Cylindrical space.

Claims

1. A housing that houses the motor and extends in the front-to-back direction, A spindle protruding from the front of the housing and rotating under the drive of the motor, with a tip tool attached to its protruding end, A controller that controls the drive of the motor, A handle mounting portion is provided at the front of the housing, from which an auxiliary handle can be attached and detached. A grinding tool comprising a handle detection mechanism for electrically detecting the mounting state of the auxiliary handle to the handle mounting portion, The housing comprises at least a cylindrical inner housing that houses the motor, and a cylindrical outer housing that covers the outside of the inner housing and extends rearward from the inner housing. The controller is housed in the outer housing behind the motor, and the handle mounting portion and the handle detection mechanism are provided in multiple locations at the front of the outer housing. A grinding tool characterized in that the wiring electrically connecting the controller and each of the handle detection mechanisms consists of a first wire connecting each of the handle detection mechanisms between the inner housing and the outer housing, and a second wire connected to the first wire, drawn out into the outer housing through the space between the inner housing and the outer housing, and connected to the controller.

2. A housing that houses the motor and extends in the front-to-back direction, A spindle protruding from the front of the housing and rotating under the drive of the motor, with a tip tool attached to its protruding end, A controller that controls the drive of the motor, A handle mounting portion is provided at the front of the housing, from which an auxiliary handle can be attached and detached. A grinding tool comprising a handle detection mechanism for electrically detecting the mounting state of the auxiliary handle to the handle mounting portion, The housing comprises at least a cylindrical inner housing that houses the motor, and a cylindrical outer housing that covers the outside of the inner housing and extends rearward from the inner housing. The controller is housed in the outer housing behind the motor, and the handle mounting portion and the handle detection mechanism are provided in multiple locations at the front of the outer housing. A grinding tool characterized in that each handle detection mechanism is electrically connected to the controller by separate wiring that runs from each handle detection mechanism through the inner housing and the outer housing into the outer housing.

3. The grinding tool according to claim 1 or 2, characterized in that the outer housing is made of resin, and each handle mounting portion is provided integrally with the outer housing.

4. The grinding tool according to claim 1 or 2, characterized in that the inner housing is held within the outer housing via an elastic member.

5. The grinding tool according to claim 1 or 2, characterized in that the wiring guide portion is provided on the outer surface of the inner housing and / or the inner surface of the outer housing.

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