Electric tool

Abstract

The invention provides an electric tool. The electric power tool has a housing, a handle, and a connector. The housing includes a housing-side connection portion having electrical conductivity. The handle includes a conductive handle-side connection portion, a detection portion capable of detecting a detection value, a handle-side conduction portion electrically connected to the detection portion, and an insulation portion electrically insulating the handle-side connection portion and the handle-side conduction portion. The connector includes a main body portion having an insulating property, and a housing-side conduction portion attached to the main body portion and electrically connected to the detection circuit. The handle-side conduction portion is electrically connected to the housing-side conduction portion in a state where the handle-side connection portion is connected to the housing-side connection portion. The housing-side conduction portion is electrically insulated from the housing-side connection portion by the main body portion. Therefore, the reduction of the detection precision of holding the handle can be inhibited or prevented.

Description

Technical Field

[0001] This invention relates to a power tool. Background Technology

[0002] A power tool is known to have a detection unit on a handle that is detachably mounted relative to a housing, used to detect information indicating the power tool's status. When the handle is mounted to the housing, the detection unit is electrically connected to a detection circuit located within the housing. For example, U.S. Patent Application Publication No. 2023 / 0158658 discloses a handle including a threaded portion for connection to a housing-side connection and a conductive portion electrically connected to the detection unit. In this power tool, the conductive portion is formed on the threaded portion, and when the handle is connected to the housing via the threaded portion, the detection unit is electrically connected to the detection circuit via the threaded portion. Summary of the Invention

[0003] In the prior art, because a conductive portion is formed on the threaded portion, if the connecting portion on the housing side is made of metal, the housing and the detection unit may become electrically connected at the same potential through the connecting portion. In this case, the detection accuracy of the detection unit and the detection circuit in detecting whether the handle is being held may be reduced.

[0004] The present invention can be implemented in the following ways.

[0005] According to one aspect of the present invention, a power tool is provided. The power tool has a housing, a handle, and at least one connector, wherein the housing includes at least one conductive housing-side connection portion; the handle, held by a user, includes a handle-side connection portion, a detection portion, a handle-side conductive portion, and an insulating portion, wherein the handle-side connection portion is detachably connected to the at least one housing-side connection portion and is conductive; the detection portion is capable of detecting a detection value; the handle-side conductive portion is electrically connected to the detection portion; and the insulating portion electrically insulates the handle-side connection portion and the handle-side conductive portion. The at least one connector has a body portion and a housing-side conductive portion, wherein the body portion is configured to be fixed to the housing and is insulating; the housing-side conductive portion is mounted on the body portion and electrically connected to a detection circuit that obtains the detection value from the detection portion. When the handle-side connection portion and the at least one housing-side connection portion are connected, the handle-side conductive portion is electrically connected to the housing-side conductive portion. The housing-side conductive portion is electrically insulated from the at least one housing-side connection portion through the body portion.

[0006] In the power tool according to the above method, with the handle mounted on the housing, the housing-side conductive portion is insulated from the housing-side connecting portion through the main body of the connector. Therefore, short circuits between the handle-side connecting portion and the housing-side connecting portion and the detection unit can be suppressed or prevented. Thus, a decrease in detection accuracy when the handle is gripped can be suppressed or prevented.

[0007] This invention can also be implemented in various ways other than power tools. For example, it can be implemented as a grinder, a power tool holding detection method, a power tool control method, a computer program implementing the control method, or a non-transitory storage medium storing the computer program. Attached Figure Description

[0008] Figure 1 It is a three-dimensional diagram showing the external structure of the grinding machine. Figure 2 It is a cross-sectional view showing the internal structure of the grinder as seen from the side. Figure 3 It is a cross-sectional view showing the internal structure of the grinder as seen from above. Figure 4 yes Figure 3 The cross-sectional view shown at position IV-IV. Figure 5 This is a three-dimensional diagram showing the appearance and structure of the secondary handle. Figure 6 yes Figure 5 The cross-sectional view at position VI-VI is shown. Figure 7 yes Figure 6 The cross-sectional view at positions VII-VII is shown. Figure 8 This is a three-dimensional view showing the external structure of the connector. Figure 9 This is the front view showing the structure of the connector. Figure 10 This is an explanatory diagram showing the electrical connection status between the handle-side conductive part of the auxiliary handle and the conductive pin of the connector. Figure 11 This is an explanatory diagram showing the method for setting the thresholds using the first and second detection values. Figure 12 This is the first flowchart representing the holding detection process performed by the controller. Figure 13 This is the second flowchart representing the holding detection process executed by the controller. Explanation of reference numerals in the attached figures 10: Housing; 11: Motor housing; 11T: Top side; 12: Power cord; 15: Gear housing; 15T: Top side; 16: Housing side connection; 17: Notification part; 18: Main handle; 19: Switch button; 20: Motor; 21: Output shaft; 22: Drive bevel gear; 26: Switch; 27, 27L, 27R: Wires; 27C: Wiring position; 30: Main shaft; 32: Driven bevel gear; 60: Secondary handle; 61: Electrode; 62: Handle side wire; 64: Insulation part; 64F: Flange part; 64T: Top part; 65: Handle side conductive part; 66: Support body; 66B: Bottom; 66R: Recess; 66T: Top part; 66W: Wall part; 67: Handle side connection; 68: Main body; 70, 70L, 70R: Connection Device; 71: Main body; 71L, 71R: Area; 72: Guide pin; 72T: Top end; 72X: Long shaft; 74: Spring; 76: Guide plate; 80: Detection circuit; 82: Controller; 91: Top tool; 92: Wheel cover; 100: Electric disc grinder; 271: First detection part; 710: Plate; 710B: Bottom surface; 710T: Opposite surface; 711: Through hole; 712: Receiving part; 712B: Bottom wall; 712L, 712R: Side wall; 713: Through hole; 714: Through hole; 715: Recess; 716: Receiving space; 720: Outer protrusion; 722: Flange; 722T: Plane; 724: Inner protrusion; CL: Clearance; DB: Force direction; DX: Drive axis; HX: Long shaft; RX: Rotation axis. Detailed Implementation

[0009] In a non-limiting embodiment of the invention, the handle-side guide portion may be positioned opposite the surface of the main body when the handle-side connecting portion and the at least one housing-side connecting portion are connected. Alternatively, the at least one connector may further include a force-applying member that applies force to cause the housing-side guide portion to protrude from the surface of the main body toward the handle-side guide portion. According to this embodiment, the housing-side guide portion contacts the handle-side guide portion when force is applied to it by the force-applying member. Therefore, for example, it is possible to suppress or prevent vibrations caused by the machining operation of the power tool at the contact point between the housing-side guide portion and the handle-side guide portion.

[0010] In addition to, or instead of, the above embodiments, the at least one connector may further include a plate component housed within the main body and having conductivity. Alternatively, the plate component may be electrically connected to the detection circuit. Alternatively, the force-applying component may be conductive, disposed on the plate component, and electrically connect the housing-side conductive portion to the plate component. Alternatively, the force-applying component may be configured to apply force to the housing-side conductive portion in a direction away from the plate component, causing the housing-side conductive portion to protrude from the surface of the main body towards the handle-side conductive portion. According to this embodiment, by using a conductive plate component, the contact area with the force-applying component can be increased. Therefore, force can be applied to the housing-side conductive portion via the force-applying component on the plate component, while simultaneously ensuring good conductivity between the housing-side conductive portion and the detection circuit via the plate component.

[0011] In addition to, or instead of, the above embodiments, the handle-side connecting portion may be an external thread or an internal thread. Alternatively, the at least one housing-side connecting portion may be configured to engage with the handle-side connecting portion using an external thread or an internal thread. Alternatively, the handle-side conductive portion may have an annular shape arranged around the handle-side connecting portion when separated from it. According to this embodiment, even when the handle is screwed to the housing and the rotational position of the handle relative to the housing changes, the handle-side conduction part and the housing-side conduction part can be made connected regardless of the rotational position of the handle.

[0012] In addition to the above-described embodiments, or alternatively to the above-described embodiments, the handle-side guide portion may be configured in a position where it is separated from the surface of the housing while the handle-side connecting portion and the at least one housing-side connecting portion are connected. According to this embodiment, when the handle is mounted on the housing, the handle-side conductive portion can be separated from the surface of the housing. Therefore, it is possible to suppress or prevent damage to the handle-side conductive portion from contact with the surface of the housing when the handle is mounted on it. Furthermore, if the housing is conductive, it is possible to suppress or prevent a short circuit between the handle-side conductive portion and the housing.

[0013] In addition to, or instead of, the above embodiments, the at least one connector may include a plurality of connectors. Alternatively, the at least one housing-side connecting portion may include a plurality of housing-side connecting portions. Alternatively, the main body portions of each of the plurality of connectors may be disposed at positions corresponding to the plurality of housing-side connecting portions. According to this embodiment, even when the handle is connected to any housing side connection, the handle's detection unit and detection circuit can be easily electrically connected via a connector.

[0014] In addition to, or instead of, the above-described embodiments, a portion of the housing-side conductive portion may be housed within the main body. Alternatively, the main body may have multiple through holes through which a wire electrically connecting the portion of the housing-side conductive portion housed within the main body and the detection circuit can be inserted. According to this embodiment, by having multiple through holes, compared with having a single through hole, the housing-side conductive part and the wire can be easily electrically connected.

[0015] In addition to, or instead of, the above-described embodiments, the housing-side guide portion may be a metal pin with a long axis. Alternatively, the main body may have a symmetrical shape with respect to the surface containing the long axis. Alternatively, the plurality of through holes may include two through holes, each disposed in one of two regions defined by the surface containing the long axis. According to this embodiment, compared to connectors with asymmetrical shapes, it is possible to reduce or prevent the operator from misplacing the connector's fixing position when securing it to the housing. Furthermore, by using connectors of the same shape, connector production efficiency can be improved.

[0016] In addition to the above-described embodiments, or as an alternative to the above-described embodiments, the top end of the housing-side guide portion may have a curved shape. According to this embodiment, even when the housing-side guide portion contacts the handle-side guide portion while being subjected to force by the force-applying component, compared to the case where the top of the housing-side guide portion is flat, damage to the handle-side guide portion due to the top of the housing-side guide portion can be suppressed or prevented.

[0017] A. Implementation Method 1: A1. Structure of power tools: Representative and non-limiting embodiments of the present invention will be specifically described with reference to the accompanying drawings. In the following embodiments, a handheld electric disc grinder 100 (hereinafter also simply referred to as "grinder 100") is listed as an example of a "power tool" according to the present invention. However, power tools are not limited to grinder 100, and may also be tools other than grinder 100, such as hammer drills, screwdrivers, belt grinders, and chainsaws.

[0018] like Figure 1As shown, the grinder 100 has a housing 10 including a main handle 18 and a secondary handle 60 configured for user gripping. The secondary handle 60 is detachably connected to the housing 10. An electrode 61 capable of detecting capacitance is provided inside the secondary handle 60. The secondary handle 60 is an example of a "secondary handle" and a "handle," and the electrode 61 is an example of a "secondary detection unit." The capacitance detected by the electrode 61 is an example of a "secondary detection value." The detailed structure of the secondary handle 60 will be described later.

[0019] The housing 10 is an elongated hollow body that forms the outer contour of the grinder 100. For example... Figure 2 As shown, a motor 20 and a main shaft 30 movably connected to the output shaft 21 of the motor 20 are housed within the housing 10.

[0020] The motor 20 is configured such that the rotation axis RX of the output shaft 21 extends substantially parallel to the long axis of the housing 10 and the main handle 18. In this embodiment, the motor 20 is operated by power supplied from an external AC power source via a power cord 12 extending from one end of the housing 10 in the direction of the long axis. However, the motor 20 may also be configured to be operated by power supplied by a rechargeable battery detachably mounted to the housing 10.

[0021] The spindle 30 is disposed within the other end of the housing 10 along its long axis. The spindle 30 is supported within the housing 10 in a manner rotatable about the drive axis DX. The drive axis DX intersects the rotation axis RX of the output shaft 21. Furthermore, in this embodiment, the drive axis DX and the rotation axis RX are orthogonal. Therefore, the grinder is sometimes also referred to as an angle grinder.

[0022] like Figure 2 As shown, one axial end of the spindle 30 protrudes outward from the housing 10. A tip tool 91 is detachably mounted at one end of the spindle 30. The tip tool 91 that can be mounted on the grinder 100 can be, for example, a grinding wheel, a cutting wheel, a blade, or a brush. The user selects a suitable tip tool 91 according to the desired work and mounts it on the grinder 100. In response to the spindle 30 being driven to rotate around the drive axis DX by the motor 20, the tip tool 91 rotates, performing machining operations on the workpiece. The grinder 100 can perform grinding, lapping, cutting, and other machining operations on the workpiece depending on the type of tip tool 91. Furthermore, the tip tool 91 is partially covered by a wheel cover 92 mounted on the housing 10.

[0023] For ease of explanation, the extension direction of the drive axis DX is defined as the vertical direction of the grinder 100. In the vertical direction, the side of the spindle 30 on which the top tool 91 is mounted is defined as the lower side of the grinder 100, and the opposite side is defined as the upper side of the grinder 100. The extension direction of the rotation axis RX of the output shaft 21 is defined as the front-back direction of the grinder 100. In the front-back direction, the side on which the spindle 30 is mounted is defined as the front side of the grinder 100, and the opposite side is defined as the rear side of the grinder 100. Directions orthogonal to the vertical and front-back directions are defined as the left-right directions of the grinder 100.

[0024] like Figure 1 As shown, the housing 10 includes a motor housing 11 and a gear housing 15 connected to the front end of the motor housing 11.

[0025] The motor housing 11 is a housing having an elongated cylindrical portion extending in the front-to-back direction. The motor housing 11 is configured to also function as a main handle 18 that can be gripped by the user. Figure 2 As shown, the motor housing 11 houses the motor 20, switch 26, detection circuit 80, and controller 82. The output shaft 21 of the motor 20 extends in the front-to-back direction. The front and rear ends of the output shaft 21 are supported by bearings.

[0026] like Figure 2 As shown, switch 26 is disposed within housing 10 behind motor 20. Switch 26 is connected to... Figure 3 The switch knob 19 shown is configured to be operated by sliding. More specifically, the switch knob 19 moves between an off position and an on position according to manual operation. The switch 26 switches on and off in response to the movement of the switch knob 19. The switch knob 19 is an example of an "operating unit". As described later, the motor 20 is driven when the main handle 18 and the auxiliary handle 60 are held and the switch 26 is in the on state. Whether the switch 26 is on is an example of a "second condition". Alternatively, instead of the switch knob 19, the operating unit may also be composed of a toggle switch, a quick-action switch, etc.

[0027] like Figure 3 As shown, the switch button 19 is disposed on the exterior of the housing 10. In this embodiment, the switch button 19 is located on the left side surface of the main handle 18. With this structure, the user can easily reach the switch button 19 with their fingers even when holding the main handle 18 from above, thereby enabling easy manual operation of the switch button 19. In addition, in this embodiment, for example, a mechanical braking device such as a friction brake is housed in the motor housing 11. When the switch button 19 is in the off position, the braking device brakes the output shaft 21 and the main shaft 30.

[0028] like Figure 2 As shown, the gear housing 15 houses the main shaft 30. Furthermore, the gear housing 15 is made of metal and is electrically conductive. The main shaft 30 is a shaft with an elongated, generally cylindrical shape. The main shaft 30 is arranged within the gear housing 15 in a vertically extending manner and is supported by multiple bearings in a manner rotatable about the drive axis DX. A driven bevel gear 32 is fixed to the upper part of the main shaft 30. The front end of the output shaft 21 of the motor 20 protrudes into the gear housing 15, and a drive bevel gear 22 that meshes with the driven bevel gear 32 is fixed to this portion.

[0029] When the motor 20 is driven, the rotation of the output shaft 21 is transmitted to the spindle 30, thereby driving the spindle 30 to rotate. As a result, the tip tool 91 fixed to the spindle 30 is driven to rotate in a predetermined direction. In addition, in this embodiment, the rotation direction of the spindle 30 is counterclockwise when viewed from above.

[0030] like Figure 1 As shown, a housing-side connecting portion 16 for connecting to the auxiliary handle 60 is formed in the housing 10. In this embodiment, the housing-side connecting portion 16 is formed on the outer surface of the gear housing 15. The housing-side connecting portion 16 has an internal thread corresponding to the handle-side connecting portion 67 described later.

[0031] like Figure 3 As shown, in this embodiment, two housing-side connecting portions 16 are formed on the housing 10 (more specifically, the gear housing 15). For example, the grinder 100 may switch between different usage methods depending on the type of top tool 91, such as having the lower side of the housing 10 positioned vertically downwards or the left side of the housing 10 positioned vertically downwards, and so on, depending on the orientation of the housing 10 when using the grinder 100. From the viewpoint of improving user convenience, it is preferable that the mounting position of the auxiliary handle 60 can be changed according to the orientation of the housing 10 when the user changes the orientation of the power tool. In the grinder 100 of this embodiment, the mounting position of the auxiliary handle 60 can be easily changed by providing multiple housing-side connecting portions 16 on the housing 10.

[0032] In this embodiment, two housing-side connecting portions 16 are respectively provided on the right and left sides of the housing 10. Figure 1 In this example, the secondary handle 60 is connected to the housing-side connecting portion 16 located on the left side of the housing 10. Furthermore, the number of housing-side connecting portions 16 is not limited to two; it can also be a single portion. Additionally, the housing 10 can have any number of housing-side connecting portions 16, including three or more. In this case, for example, in addition to the right and left sides of the housing 10, the housing-side connecting portions 16 can also be located on... Figure 1The upper top 15T of the gear housing 15 shown, or the upper top 11T of the motor housing 11, etc., on the upper side of the housing 10.

[0033] like Figure 1 As shown, in this embodiment, a connector 70 is installed near the housing-side connection portion 16. The connector 70 electrically connects the electrode 61 of the sub-handle 60, which is connected to the housing-side connection portion 16, and the detection circuit 80 inside the housing 10. The detailed structure of the connector 70 will be described later.

[0034] In this embodiment, the grinder 100 has two connectors 70. More specifically, the grinder 100 has a number of connectors 70 corresponding to the number of housing-side connection portions 16. The two connectors 70 are positioned corresponding to the two housing-side connection portions 16 respectively. With this structure, when the housing 10 is provided with multiple housing-side connection portions 16, when the auxiliary handle 60 is connected to any housing-side connection portion 16, the electrode 61 of the auxiliary handle 60 and the detection circuit 80 inside the housing 10 can be easily electrically connected via the connectors 70.

[0035] like Figure 2 As shown, the detection circuit 80 is disposed at the rear end of the housing 10 and is electrically connected to the controller 82. The detection circuit 80 includes an oscillation circuit, a resonant circuit, a detector circuit, an amplifier circuit, etc. As described later, the detection circuit 80 obtains the capacitance from the electrode 61 provided on the secondary handle 60. For example, when the user holds the secondary handle 60, the capacitance between the electrode 61 and the user's hand holding the secondary handle 60 changes relative to the capacitance when the secondary handle 60 is not held. The detection circuit 80 converts the resonant frequency that changes with the capacitance change into a voltage and outputs it to the controller 82. As described later, the detection circuit 80 obtains the capacitance from the first detection unit 271. The first detection unit 271 is provided on the main handle 18 and detects the capacitance of the main handle 18. The first detection unit 271 is an example of "first detection unit". The detection circuit 80 converts the sum of the capacitance obtained from the electrode 61 and the first detection unit 271 into a voltage and outputs it to the controller 82. The capacitance detected by the first detection unit 271 is an example of "first detection value". The voltage output by the detection circuit 80 to the controller 82 is an example of "detection result".

[0036] like Figure 2 As shown, the controller 82 is disposed at the rear end of the housing 10. The controller 82 is composed of a computer, which includes a CPU as a processor, a memory including ROM, RAM, etc., and a timer, etc. By reading and executing the information stored in the memory by the CPU, the controller 82 performs various functions implemented by the grinding machine 100 according to this embodiment.

[0037] The controller 82 performs, for example, a grip detection process to determine whether the auxiliary handle 60 and the main handle 18 are being gripped based on changes in capacitance. Specifically, the controller 82 compares the detection result (in this embodiment, the voltage value) obtained by the detection circuit 80 with a threshold stored in the memory. The controller 82 determines whether the auxiliary handle 60 and the main handle 18 are being gripped based on this comparison result. In this embodiment, when it is determined that the auxiliary handle 60 and the main handle 18 are being gripped, the controller 82 allows the motor 20 to be driven. The method for setting the threshold will be described later.

[0038] The grinder 100 of this embodiment also has a notification section 17 on the upper surface of the main handle 18. The notification section 17 is, for example, constructed using an LED light. The controller 82 turns the LED light on or off based on the detection result of whether the auxiliary handle 60 and the main handle 18 are being held correctly. As a result, the user can identify whether the auxiliary handle 60 and the main handle 18 are being held correctly.

[0039] A2. Configuration structure of conductor 27: exist Figure 3 The diagram schematically shows wires 27 disposed within the housing 10. (As shown) Figure 3 As shown, wire 27 electrically connects the detection circuit 80 and each connector 70. Wire 27 is part of the connection path that electrically connects the electrode 61 and the detection circuit 80. As a result, the detection circuit 80 is electrically connected to the electrode 61 of the auxiliary handle 60 mounted on the housing 10 via wire 27 and connector 70.

[0040] like Figure 3 As shown, in this embodiment, the wire 27 is arranged to pass through the main handle 18. With this structure, the portion of the wire 27 that passes through the main handle 18 functions as a first detection unit 271 capable of detecting the capacitance of the main handle 18.

[0041] In this embodiment, the detection circuit 80 is provided at the rear end of the motor housing 11. Therefore, compared to the case where the detection circuit 80 is provided, for example, at the center of the motor housing 11, the portion of the wire 27 that functions as the first detection unit 271 is longer in the front-rear direction. Therefore, gripping can be detected over a larger range in the front-rear direction.

[0042] Here, the connector 70 located on the right side of the housing 10 is defined as "connector 70R", and the connector 70 located on the left side of the housing 10 is defined as "connector 70L". In this embodiment, the wire 27 includes an elongated wire 27R that connects to the detection circuit 80 from the connector 70R, and a wire 27L that connects to the wire 27R at the wiring position 27C. The wire 27L connects to the wiring position 27C from the connector 70L. In other words, the single wire connected to the detection circuit 80 is configured to branch into two wires from the wiring position 27C to each of the connectors 70L and 70R. By adopting this structure, the detection circuit 80 and the electrode 61 can be electrically connected even if the auxiliary handle 60 is installed on either of the connectors 70L and 70R.

[0043] In this embodiment, the connection point 27C between wires 27R and 27L is located at the front end of the main handle 18. More specifically, the connection point 27C is positioned within the housing 10 at a location forward of the motor 20. By adopting this structure, the overall length of the wire 27 can be shortened compared to the case where the connection point 27C is positioned rearward of the motor 20. Furthermore, by defining the position of the wire 27 through the main handle 18 as a single point, the desired position for detecting the gripping position of the main handle 18 can be determined.

[0044] exist Figure 4 The diagram shows a cross-section of the main handle 18 taken along a plane passing through the switch button 19 and orthogonal to the major axis of the main handle 18. Furthermore, the major axis of the main handle 18 is approximately aligned with the rotation axis RX of the output shaft 21. In this embodiment, the wire 27 is disposed inside the main handle 18 near its outer surface. This structure improves the sensitivity of the first detection unit 271 in detecting the grip of the main handle 18.

[0045] like Figure 4As shown, in this embodiment, the wire 27 is disposed in the region RG of the cylindrical main handle 18, opposite to the switch button 19, across the rotation axis RX. The term "region RG, opposite to the switch button 19, across the rotation axis RX" refers, for example, to the set of coordinates through which the straight line connecting the various parts of the switch button 19 and the rotation axis RX passes on the opposite side of the switch button 19, across the rotation axis RX. Thus, the first detection unit 271 is disposed away from the switch button 19. With this structure, when the first detection unit 271 detects that the main handle 18 is being held and the switch button 19 can be manually operated, it can be presumed that the main handle 18 is reliably held within approximately the range from the switch button 19 to the first detection unit 271. Therefore, compared to disposing the first detection unit 271 near the switch button 19, it is possible to detect not only the user touching a portion of the main handle 18, but also the state surrounding the user holding the main handle 18.

[0046] A3. Structure of the secondary handle 60: like Figure 5 and Figure 6 As shown, the secondary handle 60 has a main body 68, a support 66, a handle-side connecting part 67, an insulating part 64, a handle-side conductive part 65, an electrode 61, and a handle-side wire 62.

[0047] The main body 68 has a generally cylindrical shape extending along its long axis HX, configured to be held by a user. The main body 68 is an example of a "holding part." Figure 6 As shown, an electrode 61 and a portion of a handle-side connection portion 67 are disposed within the main body portion 68.

[0048] like Figure 6 As shown, the handle-side connecting portion 67 is an externally threaded portion configured to engage with the housing-side connecting portion 16 of the housing 10. The handle-side connecting portion 67 extends along its long axis HX and is fixed within the main body portion 68. In this embodiment, the handle-side connecting portion 67 is formed of a metal material. As described above, since the housing-side connecting portion 16 is also formed of a metal material, when the handle-side connecting portion 67 is connected to the housing-side connecting portion 16, the housing-side connecting portion 16 and the handle-side connecting portion 67 can become electrically equivalent to each other. Furthermore, if the housing-side connecting portion 16 is formed of an externally threaded portion, the handle-side connecting portion 67 can also be formed of an internally threaded portion.

[0049] like Figure 6As shown, the support body 66 has a generally cylindrical shape extending along its long axis HX. The support body 66 is formed of an insulating material and is connected to the main body 68. With the auxiliary handle 60 mounted on the housing 10, the top end 66T of the support body 66 faces the housing 10. At the top end 66T of the support body 66, a wall portion 66W extending from the periphery of the top end 66T toward the housing 10 side and a bottom portion 66B surrounded by the wall portion 66W are formed. A handle-side guide portion 65 is disposed in the recess 66R defined by the wall portion 66W and the bottom portion 66B.

[0050] The handle-side guide section 65 is a roughly circular metal plate component. For example... Figure 6 As shown, the handle-side conductive part 65 is electrically connected to the electrode 61 via the handle-side wire 62. When the auxiliary handle 60 is installed in the housing 10, the handle-side conductive part 65 is arranged opposite to the housing 10 and the connector 70, and is configured to contact the conductive pin 72 protruding from the connector 70, but details will be described later.

[0051] In this embodiment, a handle-side guide portion 65 is disposed in the recess 66R of the support body 66, and a gap CL is formed between the surface of the handle-side guide portion 65 and the top end of the wall portion 66W of the top end portion 66T of the support body 66. With this structure, when the auxiliary handle 60 is mounted on the housing 10, the handle-side guide portion 65 can be positioned separately from the surface of the housing 10 (see reference). Figure 10 Therefore, it is possible to suppress or prevent short circuits between the handle-side conductive part 65, for example, and the gear housing 15.

[0052] like Figure 5 As shown, in this embodiment, the handle-side guide portion 65 has a generally annular shape surrounding the handle-side connecting portion 67. Here, in the grinder 100 of this embodiment, the auxiliary handle 60 is screwed onto the housing 10 via the handle-side connecting portion 67 and the housing-side connecting portion 16. When the auxiliary handle 60 is installed onto the housing 10, it rotates relative to the housing 10 and the connector 70 about its major axis HX. Therefore, the relative position of the handle-side guide portion 65 with respect to the guide pin 72 protruding from the connector 70 changes depending on the rotational position of the auxiliary handle 60.

[0053] In this embodiment, the handle-side conductive portion 65 is configured in a ring shape, so that when the handle-side connecting portion 67 and the housing-side connecting portion 16 are screwed together, their rotational trajectory relative to the handle-side connecting portion 67 coincides. By employing this structure, the handle-side conductive portion 65 and the conductive pin 72 can be made in contact regardless of the rotational position of the auxiliary handle 60 relative to the housing 10. Therefore, even when the auxiliary handle 60 is screwed onto the housing 10, it is possible to suppress or prevent the handle-side conductive portion 65 and the conductive pin 72 from not contacting, resulting in a lack of electrical connection between the electrode 61 and the detection circuit 80.

[0054] like Figure 6 As shown, the handle-side conductive portion 65 is configured in a state separated from the handle-side connecting portion 67 in order to insulate it from the handle-side connecting portion 67. In this embodiment, by providing an insulating portion 64 between the handle-side conductive portion 65 and the handle-side connecting portion 67, the handle-side conductive portion 65 and the handle-side connecting portion 67 are configured to be insulated.

[0055] The insulating part 64 is a generally cylindrical component formed using insulating material. An internal thread corresponding to the external thread formed on the handle-side connecting part 67 is formed on the inner circumferential surface of the insulating part 64. The insulating part 64 is screwed onto the handle-side connecting part 67 and fixed in such a way that it surrounds a portion of the handle-side connecting part 67. By using the simple structure of the insulating part 64, short circuits between the handle-side conductive part 65 and the handle-side connecting part 67 can be suppressed or prevented.

[0056] At the top end 64T of the insulating portion 64, a flange portion 64F is formed that protrudes radially outward in a direction further away from the major axis HX than other portions. With the handle-side conductive portion 65 disposed in the recess 66R of the support body 66, the handle-side conductive portion 65 is clamped and fixed by the bottom 66B of the support body 66 and the flange portion 64F of the insulating portion 64 by screwing the insulating portion 64 onto the handle-side connecting portion 67.

[0057] Furthermore, the length of the gap CL is approximately the same as the thickness of the flange 64F. Therefore, as Figure 6 As shown, the top end 64T of the insulating portion 64 and the top end of the wall portion 66W of the top end 66T of the support body 66 are approximately coplanar. Therefore, when the secondary handle 60 is installed on the housing 10, the wall portion 66W of the support body 66 and the top end 64T of the insulating portion 64 in the secondary handle 60 first come into contact with the outer surface of the gear housing 15. That is, the part of the secondary handle 60 formed by the insulator is configured to contact the outer surface of the metal gear housing 15. By adopting this structure, the gear housing 15 and the electrode 61 are prevented from becoming at the same potential.

[0058] like Figure 6 and Figure 7As shown, electrode 61 has a generally cylindrical shape extending along its long axis HX. Electrode 61 is arranged around the long axis HX of the sub-handle 60, configured to cover the entire circumference of the main body 68 of the sub-handle 60 for detecting electrostatic capacitance.

[0059] In addition, such as Figure 7 As shown, in this embodiment, the distance DH from the electrode 61 to the outer surface of the main body 68 in the radial direction of the secondary handle 60 covers the entire circumference of the secondary handle 60 centered on the major axis HX and is approximately the same. Therefore, the sensitivity of the electrode 61 to capacitance is substantially non-anisotropic in the circumferential direction of the major axis HX. Therefore, even if the rotational position of the secondary handle 60 relative to the housing 10 changes due to the screwing of the housing 10 and the secondary handle 60, the change in the sensitivity of the electrode 61 to capacitance according to the rotational position can be suppressed. In addition, it is possible to suppress or prevent the influence of the user's gripping position on the secondary handle 60 on the detection sensitivity of capacitance. That is, when the secondary handle 60 is fixed in a predetermined position in the housing 10 by screwing or the like, the gripping of the secondary handle 60 can be detected regardless of the direction and posture of the gripping part relative to the housing 10, even if the direction and posture of the secondary handle 60 are different each time it is attached or detached.

[0060] A4. Structure of Connector 70: As described above, connector 70 electrically connects the electrode 61 of the auxiliary handle 60, which is connected to the housing 10 via the housing-side connection portion 16, to the detection circuit 80 within the housing 10. Figure 8 As shown, connector 70 includes a main body 71, a guide pin 72, a spring 74, and a guide plate 76.

[0061] The main body 71 is formed of, for example, a resin material and has insulating properties. The main body 71 includes a plate portion 710 and a receiving portion 712 extending from the plate portion 710.

[0062] The plate portion 710 has a facing surface 710T and a bottom surface 710B opposite to the facing surface 710T. A through hole 711 is formed in the center of the facing surface 710T, extending from the facing surface 710T to the bottom surface 710B. When the connector 70 is installed in the housing 10 (more specifically, the gear housing 15), the facing surface 710T protrudes outward from the housing 10 and faces the secondary handle 60.

[0063] The receiving portion 712 is housed inside the housing 10 when the connector 70 is installed in the housing 10. The receiving portion 712 includes two side walls 712R and 712L connected to the bottom surface 710B and a bottom wall 712B connecting the two side walls 712R and 712L. The bottom wall 712B is arranged opposite to the bottom surface 710B of the plate portion 710.

[0064] like Figure 8As shown, recesses 715 are formed on the two sidewalls 712R and 712L by cutting off a portion of the sidewalls 712R and 712L, respectively. The recesses 715 fix the main body 71 to the housing 10 by engaging or fitting with the housing 10.

[0065] like Figure 9 As shown, a receiving space 716 is formed approximately in the center of the main body 71, defined by two side walls 712R and 712L, a bottom wall 712B, and a bottom surface 710B. The receiving space 716 receives a portion of the guide pin 72, a spring 74, and a guide plate 76.

[0066] The conductive plate 76 is, for example, a plate-shaped component with electrical conductivity. The conductive plate 76 is electrically connected to the wire 27 by welding, fusion, or bonding.

[0067] Two through holes 714 and 712L are formed on the two sidewalls 712R and 712L, respectively, extending from the receiving space 716 to one side and through holes 713 extending from the receiving space 716 to the opposite side of the through hole 714. Specifically, the through hole 713 is formed on the sidewall 712L and the through hole 714 is formed on the sidewall 712R. The through holes 713 and 714 connect the position of the guide plate 76 in the receiving space 716 to the outside of the main body 71.

[0068] The through holes 713 and 714 are configured to allow the wire 27 to pass through. Since the main body 71 has multiple through holes 713 and 714, the wire 27 can be guided from multiple locations outside the connector 70 to the receiving space 716. Therefore, compared to the case where the main body 71 has a single through hole, the guide pin 72 and the wire 27 can be easily electrically connected. When the connector 70 is installed in multiple locations on the housing 10, the relative position of the wire 27 disposed within the housing 10 and the connector 70 may differ depending on the configuration of the connector 70. By having multiple through holes 713 and 714 in the main body 71, it is easy to guide the wire 27 from the outside of the connector 70 to the receiving space 716, improving the versatility of the connector 70's configuration relative to the housing 10. Furthermore, the number of through holes is not limited to two; it can be one, three, or any other number.

[0069] like Figure 9 As shown, the main body 71 has a surface-symmetrical shape that is symmetrical with respect to the plane including the major axis 72X. Therefore, the connector 70 can be easily arranged at multiple positions of the housing 10, such as the right side, left side, or center of the housing 10.

[0070] Furthermore, through holes 713 and 714 are also positioned symmetrically with respect to the plane including the major axis 72X. For example... Figure 9As shown, when the two regions divided by the plane including the major axis 72X are designated as region 71L and region 71R, a through hole 713 is included in region 71L, and a through hole 714 is included in region 71R. Due to the symmetrical shape, connectors 70 of the same shape can be easily positioned at different locations on the housing 10. Therefore, compared to using connectors 70 with asymmetrical shapes, the process of the operator determining the installation position of the connector 70 can be eliminated. Thus, the occurrence of operators misjudging the installation position of the connector 70 can be reduced or prevented. Furthermore, since connectors 70 of the same shape can be produced, the production efficiency of the connectors 70 can be improved.

[0071] like Figure 9 As shown, the guide pin 72 is a rod-shaped component with a long axis 72X. The guide pin 72 is formed of a metal material or the like and is conductive. The guide pin 72 is an example of a "housing-side guide portion" and a "pin". The guide pin 72 is formed by connecting an outer protrusion 720, a flange portion 722, and an inner protrusion 724 along the long axis 72X.

[0072] The outer protrusion 720 is inserted through the through hole 711 of the plate portion 710 and protrudes outward from the opposite surface 710T of the main body portion 71. The inner protrusion 724 is disposed in the receiving space 716 and is inserted through the spring 74. The flange portion 722 is disposed between the outer protrusion 720 and the inner protrusion 724 and is configured to have a diameter larger than both the outer protrusion 720 and the inner protrusion 724.

[0073] Spring 74 is, for example, a compression coil spring. Spring 74 is an example of a "force-applying component". Spring 74 is made of a metallic material and is conductive. When spring 74 is disposed on the guide plate 76, it applies force to the guide pin 72 in the force-applying direction DB. The force-applying direction DB refers to the direction in which the guide pin 72 protrudes outward from the opposite surface 710T (away from the guide plate 76), which is the direction in which the guide pin 72 approaches the handle-side guide portion 65. The force-applying direction DB is parallel to the long axis 72X. The outer protrusion 720 in the guide pin 72 protrudes from the surface of the main body portion 71 by being forced by spring 74 in the force-applying direction DB. The plane 722T of the flange portion 722 connecting the outer protrusion 720 restricts its movement in the force-applying direction DB by contacting the bottom surface 710B.

[0074] like Figure 10 As shown, within the housing 10, the wire 27 is arranged to be guided from the detection circuit 80 to the connector 70. The wire 27 guided to the connector 70 is guided from the through hole 713 or through hole 714 formed in the main body 71 to the receiving space 716 and is electrically connected to the conductive plate 76.

[0075] like Figure 10As shown, one end of the spring 74 contacts the conductive plate 76, and the other end of the spring 74 contacts the flange 722 of the conductive pin 72. The wire 27 is electrically connected to the conductive pin 72 through the conductive plate 76 and the spring 74. By using the conductive plate 76, compared to the case where the wire 27 and the spring 74 are directly connected, the contact area between the spring 74 and the wire 27 can be increased. Therefore, the conductive plate 76 can be used to properly conduct the wire 27 and the spring 74.

[0076] The handle-side conductive part 65 of the auxiliary handle 60 is electrically connected to the electrode 61 via the handle-side wire 62. The conductive pin 72, which is force-applied in the force direction DB by the spring 74, contacts the handle-side conductive part 65 and is electrically connected to it. As a result, the electrode 61 and the detection circuit 80 are electrically connected via the connector 70.

[0077] The top end 72T of the outer protrusion 720 contacts the handle-side guide portion 65 of the auxiliary handle 60 when the spring 74 applies force in the direction of force DB. By adopting this structure, it is possible to suppress or prevent the guide pin 72 from moving away from the handle-side guide portion 65. Therefore, for example, it is possible to suppress or prevent vibration of the handle-side guide portion 65 and the guide pin 72 due to the processing operation of the grinding machine 100.

[0078] As described above, when the handle-side connecting portion 67 and the housing-side connecting portion 16 are screwed together, the rotation trajectory of the guide pin 72 overlaps with the handle-side guide portion 65. When the auxiliary handle 60 is installed on the housing 10 by screwing it together, the guide pin 72 moves on the handle-side guide portion 65 while in contact with it and under the force of the spring 74. Therefore, through the friction between the tip 72T of the guide pin 72 and the handle-side guide portion 65, foreign matter such as oxide film on the surface of the handle-side guide portion 65 can be removed. Therefore, it is possible to suppress or prevent a decrease in the conductivity of the handle-side guide portion 65 and the guide pin 72.

[0079] In addition, such as Figure 9 As shown, the top end 72T of the guide pin 72 has a curved shape. Therefore, even when the guide pin 72 moves on the handle-side guide portion 65 under the force of the spring 74, compared to the case where the top end 72T is flat, damage to the handle-side guide portion 65 due to the top end 72T can be suppressed or prevented.

[0080] A5. Threshold setting method: exist Figure 11 Examples of test results (the sum of the capacitance obtained by the electrode 61 and the first detection unit 271) are shown when the secondary handle 60 and the main handle 18 are held in three different ways. Figure 11 In the example, the vertical axis of the graph represents voltage.

[0081] The left end of the graph represents the detection result D1 when the main handle 18 is held and the secondary handle 60 is not held. Detection result D1 is an example of "Detection Result 1". In detection result D1, the peak voltage is voltage V1.

[0082] The graph shows the test result D2 in the state where the main handle 18 is not held and the secondary handle 60 is held. Test result D2 is an example of "second test result". In test result D2, the peak voltage is voltage V2.

[0083] As described above, in this embodiment, the portion of the wire 27 passing through the main handle 18 functions as the first detection unit 271. When the surface area of ​​the portion of the wire 27 passing through the main handle 18, i.e., the surface area of ​​the first detection unit 271, is compared with the surface area of ​​the electrode 61 of the sub-handle 60, the surface area of ​​the electrode 61 is larger than the surface area of ​​the first detection unit 271. Therefore, as... Figure 11 As shown, the sensitivity of the first detection unit 271 to capacitance is lower than that of the electrode 61 to capacitance. That is, voltage V1 is lower than voltage V2.

[0084] The right end of the graph shows the detection result D3 with both the main handle 18 and the auxiliary handle 60 held. Detection result D3 is also referred to as "third detection result". In detection result D3, the peak voltage is voltage V3.

[0085] like Figure 3 As shown, in the grinding machine 100 of this embodiment, the electrode 61 of the auxiliary handle 60 and the first detection section 271 of the main handle 18 are electrically connected to the detection circuit 80 via wire 27. Therefore, when both the auxiliary handle 60 and the main handle 18 are held, the voltage V3 is approximately equal to the sum of voltages V1 and V2.

[0086] exist Figure 11 The diagram shows an example of a threshold TH stored in the memory of the controller 82 in this embodiment. The threshold TH is set using a value greater than voltage V2 and less than voltage V3, which is the sum of voltages V1 and V2. That is, the detection result is above the threshold TH when only the secondary handle 60 and the main handle 18 are held. Whether the detection result is above the threshold TH is an example of a "first condition." When the detection result exceeds the threshold TH, the controller 82 determines that the first condition is met and allows the motor 20 to be driven. When only either the secondary handle 60 or the main handle 18 is held, the detection result is less than the threshold TH. In this case, the controller 82 determines that the first condition is not met and does not allow the motor 20 to be driven.

[0087] A6. Control and detection processing: For example, when power is supplied to the grinder 100 via power cord 12 or a rechargeable battery, or when the process is restarted after completion. Figure 12 and Figure 13 The process is shown below. Additionally, in the following explanation, each "step" in the process will be simply referred to as "S".

[0088] In S10, the controller 82 performs calibration. In this embodiment, calibration refers to adjusting the output of the electrode 61 and the first detection unit 271 to remove noise. Figure 11 The threshold TH shown is processed. Controller 82 uses the voltage value obtained from detection circuit 80 to detect the non-grip state of both the secondary handle 60 and the main handle 18. Whether it is in a non-grip state can be determined, for example, based on whether the obtained voltage value is less than voltage V1.

[0089] When the controller 82 determines that it is in a non-holding state, it adjusts the threshold TH using the voltage value acquired in the non-holding state. For example, the controller 82 changes the threshold TH to a new threshold by adding the voltage value acquired in the non-holding state as an offset value including noise, etc. That is, the voltage value detected in the non-holding state is removed as noise. Furthermore, the adjustment of the threshold TH includes so-called zero-point correction. For example, instead of changing the threshold TH, the adjustment of the threshold TH also includes changing the value obtained by subtracting the voltage value acquired in the non-holding state from the reference value VS to a new reference value.

[0090] Furthermore, when calibration is performed while the user is holding at least one of the secondary handle 60 and the main handle 18, the threshold TH may be set too high. Therefore, in this embodiment, calibration is performed using the detection results from the non-holding state.

[0091] In S20, the controller 82 acquires the voltage value as a detection result from the detection circuit 80. In S30, the controller 82 compares the acquired voltage value with the threshold TH. If the acquired voltage value is less than the threshold TH (S30: No), the controller 82 transfers the process to S34. In S34, the controller 82 disables the motor drive and transfers the process to S10. In this case, even if the user puts the switch button 19 in the ON position, the motor 20 will not be driven.

[0092] In S30, if the acquired voltage value is above the threshold TH (S30: Yes), the controller 82 transfers the processing to S32, determining that the first condition is met. Additionally, in this embodiment, in S30, the controller 82 also confirms that the second condition is not met. In S40, the controller 82 allows the motor 20 to be driven. In S50, the controller 82 illuminates the LED light on the notification unit 17. The user recognizes that the first condition has been met by the illumination of the notification unit 17, and can also recognize that the user is in a state where the motor 20 can be driven by operating the switch button 19.

[0093] In S60, the controller 82 monitors whether the switch 26 is on. If the switch 26 is off (S60: No), the controller 82 transfers the processing to S64.

[0094] In S64, the controller 82 determines, for example, whether a predetermined time has elapsed since the execution of S32 or S40. If the predetermined time has not elapsed (S64: No), the controller 82 transfers the process to S60. When the predetermined time has elapsed (S64: Yes), the controller 82 transfers the process to S66. In S66, the controller 82 turns off the LED light on the notification unit 17, ending the process. If the user is holding the auxiliary handle 60 and the main handle 18 but the switch button 19 has not been operated and the predetermined time has elapsed, the user may not intend to use the grinder 100 at that time. Therefore, in this case, the motor 20 is not driven, ending the process.

[0095] If switch 26 is detected to be on in S60 (S60: Yes), controller 82 transfers the processing to S62, determining that condition 2 is met. In S70, controller 82 drives motor 20. As a result, the top tool 91 fixed to spindle 30 is driven to rotate.

[0096] like Figure 12 and Figure 13 As shown, in this embodiment, after the controller 82 confirms in S30 that the second condition is not met and determines in S32 that the first condition is met, it then determines whether the second condition is met. In other words, if the first condition is met after the switch 26 is turned on, the motor 20 is not driven. By employing this control, for example, it is prevented that the motor 20 is driven at the moment when the gripping of the secondary handle 60 is detected after the main handle 18 is held and the switch button 19 is turned on. By employing this structure, it is possible to prevent the motor 20 from being driven when the secondary handle 60 is not being held sufficiently.

[0097] In S80, the controller 82 acquires a voltage value from the detection circuit 80. That is, while the motor 20 is in the driving state, the controller 82 continuously detects the gripping of the auxiliary handle 60 and the main handle 18. In S90, the controller 82 compares the acquired voltage value with a threshold TH. If the acquired voltage value is above the threshold TH (S90: Yes), the controller 82 transfers the process to S92 to check whether the switch 26 is open. If the switch 26 is in the closed state (S92: No), the controller 82 transfers the process to S80. If the switch 26 is open (S92: Yes), the controller 82 transfers the process to S100.

[0098] In S90, if the acquired voltage value is less than the threshold TH (S90: No), the controller 82 transfers the processing to S100. For example, the voltage value becomes less than the threshold TH when at least one of the secondary handle 60 and the main handle 18 is no longer held.

[0099] In step S100, the controller 82 turns off the LED light on the notification unit 17 to inform the user that the conditions for driving the motor 20 are not met. In step S110, the controller 82 stops the motor 20, thus ending the process.

[0100] As explained above, in the grinding machine 100 of this embodiment, the first detection result when the main handle 18 is held and the secondary handle 60 is not held is less than the second detection result when the main handle 18 is not held and the secondary handle 60 is held. That is, the detection accuracy for holding the secondary handle 60 is higher than the detection accuracy for holding the main handle 18. Therefore, compared to providing a mechanical switch such as a switch button on the secondary handle 60, it is possible to detect whether the secondary handle 60 is being held sufficiently with a simpler structure. Furthermore, the holding of the secondary handle 60 and the main handle 18 is detected by comparing the sum of the first and second detection results with a threshold TH. Therefore, it is possible to detect the holding of the secondary handle 60 and the main handle 18 using a simpler method than determining the holding of the main handle 18 and the secondary handle 60 separately.

[0101] The grinding machine 100 of this embodiment includes a connector 70, which comprises an insulated main body 71 and a conductive pin 72 mounted on the main body 71 and electrically connected to the detection circuit 80. When the handle-side connecting portion 67 of the secondary handle 60 is connected to the housing-side connecting portion 16 of the housing 10, the handle-side conductive portion 65 is electrically connected to the conductive pin 72 of the connector 70, and the conductive pin 72 is electrically insulated from the housing-side connecting portion 16 by the main body 71. Therefore, when the secondary handle 60 is connected to the housing 10, the electrode 61 is electrically connected to the detection circuit 80 via the connector 70. Furthermore, since the conductive pin 72 is insulated by the main body 71, short circuits between the electrode 61 and the connection points of the handle-side connecting portion 67 and the housing-side connecting portion 16 can be suppressed or prevented. Therefore, a decrease in detection accuracy when the secondary handle 60 and the main handle 18 are held can be suppressed or prevented.

[0102] Furthermore, in power tools, as a non-limiting objective, a technology is provided that can detect whether both the main handle and the auxiliary handle are being held using a simple structure. The following methods B1 to B10 are provided. Methods B1 to B10 can be used individually or in combination of two or more. Alternatively, at least one of methods B1 to B10 can be used in combination with the grinder 100 of the embodiment, the aforementioned modifications, and at least one of the features described in each technical solution.

[0103] [Method B1] A type of power tool, It has a motor, main handle, auxiliary handle, detection circuit and controller, among which, The motor is driven by electricity; The main handle is configured so that the user can hold it with one hand, and the main handle includes a first detection unit that can detect a first detection value corresponding to the holding. The secondary handle is configured so that the user can hold it with his other hand, and the secondary handle includes a second detection unit capable of detecting a second detection value corresponding to the holding. The detection circuit acquires the first detection value and the second detection value from the first detection unit and the second detection unit, and outputs a detection result related to the acquired first detection value and the second detection value; The controller acquires the detection result from the detection circuit, and allows the motor to be driven if the acquired detection result is above a first condition. The first detection result is less than the second detection result, wherein the first detection result refers to the detection result when the main handle is held and the secondary handle is not held, and the second detection result refers to the detection result when the main handle is not held and the secondary handle is held. The threshold is greater than the second detection result and is less than the sum of the first detection result and the second detection result.

[0104] According to the power tool described in method B1, the sensitivity of the secondary handle is set to be higher than that of the primary handle, and whether either handle is being gripped is detected by comparing the sum of the first and second detection results with a threshold. Therefore, the detection accuracy for gripping the secondary handle can be set to be higher than that for gripping the primary handle, and the gripping of both the secondary and primary handles can be detected using a simpler method than determining gripping of the primary and secondary handles separately.

[0105] [Method B2] The power tools according to method B1 The first detection unit and the second detection unit are configured to acquire capacitance. The surface area of ​​the second detection unit is larger than that of the first detection unit. According to method B2, the detection sensitivity of the second detection unit can be made higher than that of the first detection unit by means of a simple structure.

[0106] [Method B3] The power tools according to method B1 or method B2 The first detection unit is configured in a connection path that electrically connects the second detection unit and the detection circuit. According to method B3, since both the first detection unit and the second detection unit are provided in one connection path, compared with the case where the first detection unit is individually connected to the second detection unit and the detection circuit through multiple connection paths, the main handle and the auxiliary handle and the detection circuit can be electrically connected with a simple structure.

[0107] [Method B4] The power tools according to method B3 The second detection unit and the detection circuit are electrically connected by wires. The wire is configured via the main handle. The portion of the wire that passes through the main handle is configured to function as the first detection unit. According to method B4, the grip of the main handle can be detected by using a portion of the wire arranged inside the main handle as a simple structure of the first detection unit.

[0108] [Method B5] Electric tools according to any one of methods B1 to B4, The main handle has an operating section configured to switch between an on / off state and an off / on state. The controller drives the motor when the first condition is met and the second condition, which is that the operating unit is in the on state, is met. According to method B5, the motor is driven when the gripping of the main handle and the sub-handle is detected and the operation unit is in the on state. Therefore, it is possible to suppress or prevent the motor from being driven when neither the main handle nor the sub-handle is being fully gripped.

[0109] [Method B6] The power tools according to method B5 The main handle is a cylindrical part with a long shaft. The first detection unit is disposed in a region on the opposite side of the operation unit, separated from the long axis, in a plane orthogonal to the long axis. According to method B6, compared with the method of arranging the first detection unit near the operation unit, it is possible to detect the state in which the cylindrical main handle is reliably held.

[0110] [Method B7] Electric tools according to any one of methods B1 to B6, It also has a housing that accommodates the motor. The secondary handle includes a grip portion that can be held by the user. The secondary handle is configured to be detachable from the housing. The second detection unit is configured to detect the second detection value covering the entire circumference of the gripping unit. According to method B7, when the secondary handle is fixed in a specified position on the housing, the gripping of the secondary handle can be detected even if the direction and posture are different each time the secondary handle is removed or installed, regardless of the direction and posture of the gripping part relative to the housing.

[0111] [Method B8] Electric tools according to any one of methods B1 to B7, The controller uses the detection results obtained by the detection circuit to detect the non-grip state of the main handle and the secondary handle, indicating that they are not being gripped. After adjusting the threshold using the detection result obtained from the non-holding state, the control unit determines whether the first condition is met. According to method B8, the detection results detected in the non-grip state can be removed as noise, thereby suppressing or preventing the reduction of the detection accuracy of the grip detection of the main handle and the sub-handle.

[0112] [Method B9] Electric tools according to any one of methods B1 to B8, The power tool is a grinder having a housing for housing the motor. Multiple connectors, configured to be detachable from the secondary handle, are located at multiple positions on the housing. When the secondary handle is installed in any of the plurality of connectors, the second detection unit and the detection circuit are electrically connected. According to method B9, even in power tools such as grinders where the mounting position of the secondary handle can be easily changed to allow the user to switch the direction of the housing during use, the gripping of the secondary handle can be detected according to its mounting position.

[0113] [Method B10] Electric tools according to any one of methods B1 to B9, It also has a notification section, which is used to inform the user whether the obtained test results meet the first condition. According to method B10, the user can identify that condition 1 is met through the notification department.

[0114] B. Other implementation methods: The above embodiments are merely examples, and the power tools involved in the present invention and the above-described embodiments B1 to B10 are not limited to the grinder 100 of the above embodiments. For example, the following non-limiting example modifications can also be made. In addition, at least one of these modifications can be used in combination with the grinder 100 of the embodiments and at least one of the features described in the technical solution.

[0115] (B1) In the first embodiment described above, the structure in which the wire 27 passes through the main handle 18 will be used as an example. In contrast, the wire 27 may not pass through the main handle 18, but may only be disposed on a part of the main handle 18. For example, even if the detection circuit 80 is disposed in the center of the main handle 18 or in a position forward of the motor 20, the wire 27 can still function as the first detection unit 271.

[0116] (B2) In the first embodiment described above, a structure is shown in which a single wire connected to the detection circuit 80 branches into two wires from the wiring position 27C to each of the connectors 70L and 70R. In contrast, the wire 27 may also include two wires: one connecting to the detection circuit 80 from the connector 70R, and the other connecting to the detection circuit 80 from the connector 70L. In this case, the two wires are respectively arranged via the main handle 18, thereby allowing the first detection unit 271 to be installed at multiple positions on the main handle 18. In this case, the first detection value can be the detection values ​​of both wires, or it can be the detection value of any one of the two wires.

[0117] (B3) In the first embodiment described above, an example of performing grip detection on the secondary handle 60 and the main handle 18 is shown, but grip detection can also be performed on positions other than the secondary handle 60 and the main handle 18. In this case, a wire is added at the position where grip detection is desired, and the added wire is connected to the wire 27R. The number of grip detection positions can be increased by such a simple structure as adding wires.

[0118] For example, if we consider switching the orientation of the housing 10 when using a power tool, such as a grinder 100, depending on the type of the tip tool 91, it is possible to switch the user's gripping position on the main handle 18. In this case, it is preferable to provide the first detection unit 271 at multiple locations on the main handle 18. For example, in addition to the wire 27R disposed on the right side of the main handle 18, a wire is also disposed on the upper side of the main handle 18. By adopting this structure, even if the user's gripping position is switched to the right side or the upper side of the main handle 18, the gripping of the main handle 18 can be detected.

[0119] (B4) In the first embodiment described above, an example is shown where the detection circuit 80 is disposed at the rear end of the housing 10, and the main handle 18 and the first detection unit 271 are disposed between the detection circuit 80 and the auxiliary handle 60. In contrast, the detection circuit 80 may also be disposed at the center or front end of the housing 10, and the main handle 18 and the first detection unit 271 may be disposed at a position further rearward than the detection circuit 80. In this case, for example, the wires connected to the detection circuit 80 may branch as wires from the connector 70 to the auxiliary handle 60, and wires from the detection circuit 80 to the first detection unit 271 located further rearward than the detection circuit 80. Even with this structure, the same effects as in the first embodiment described above can be obtained.

[0120] (B5) In the first embodiment described above, an example is shown where the electrode 61 provided on the secondary handle 60 and the first detection unit 271 provided on the main handle 18 acquire capacitance, and the voltage value obtained by converting the acquired capacitance is used as the detection result for grip detection processing. In contrast, in grip detection processing, if the detection sensitivity of the second detection unit is higher than that of the first detection unit, the second and first detection units can also acquire detection values ​​other than capacitance. The first and second detection units can, for example, be FSR (Force Sensing Resistors) type sensors. In this case, the detection circuit 80 acquires the voltage change caused by the change in resistance value due to pressure when gripping the handle from the first and second detection units as the detection value. Alternatively, the detection circuit 80 can acquire physical quantities other than pressure, capacitance, and voltage as the first and second detection values, for example. Pressure and voltage are examples of "first detection value" and "second detection value".

[0121] (B6) In the first embodiment described above, an example is shown where an electrode 61 having a generally cylindrical shape extending along the long axis HX functions as a second detection unit. In contrast, provided the detection sensitivity of the second detection unit is higher than that of the first detection unit, the second detection unit may, for example, be an electrode having a shape other than a cylinder, such as a plate extending along the long axis HX, or an electrode having a rod-shaped member having a generally cylindrical shape extending along the long axis HX. Alternatively, instead of an electrode, the second detection unit may be a wire 27 wound with multiple turns, etc.

[0122] (B7) In the first embodiment described above, an example is shown where the portion of the wire 27 passing through the main handle 18 functions as the first detection unit 271. In contrast, provided the detection sensitivity of the second detection unit is higher than that of the first detection unit, for example, the first detection unit 271 may also be an electrode or other component besides the wire 27, having a surface area smaller than that of the electrode 61 of the sub-handle 60. The electrode may also be any shape, such as cylindrical, cylindrical, plate-shaped, or rod-shaped.

[0123] (B8) In the above embodiments, an example is shown where the controller 82 is composed of a computer including a CPU, ROM, RAM, etc. In contrast, the controller 82 may also be composed of programmable logic devices such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field Programmable Gate Arrays). The drive control processing in the above embodiments can also be implemented by the CPU executing a program stored in the ROM. In this case, the program can be pre-stored in the ROM of the controller 82, and if the controller 82 includes non-volatile memory, the program can also be stored in non-volatile memory. Alternatively, the program can be stored on an external storage medium capable of reading data (e.g., a USB memory). The drive control processing in the above embodiments and variations can also be processed by multiple control circuits distributed across the process.

[0124] This invention is not limited to the embodiments described above, and can be implemented with various structures without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features described in the summary section can be appropriately replaced or combined to solve some or all of the above-described technical features, or to achieve some or all of the above-described effects. In addition, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

Claims

1. A power tool, characterized in that, It has a housing, a handle, and at least one connector, wherein, The housing includes at least one housing-side connection portion that is conductive; The handle, held by the user, includes a handle-side connecting part, a detection part, a handle-side conductive part, and an insulating part. The handle-side connector is detachably connected to at least one housing-side connector and is conductive; The detection unit is capable of detecting values; The handle-side conductive part is electrically connected to the detection part; The insulating part electrically insulates the handle-side connecting part and the handle-side conductive part; The at least one connector has a main body portion and a housing-side conductive portion, wherein... The main body is configured to be fixed to the housing and has insulation properties; The housing-side conductive portion is mounted on the main body and is electrically connected to the detection circuit that obtains the detection value from the detection unit. With the handle-side connecting portion and the at least one housing-side connecting portion connected, The handle-side conductive part is electrically connected to the housing-side conductive part; The housing-side conductive portion is electrically insulated from the at least one housing-side connecting portion through the main body portion.

2. The power tool according to claim 1, characterized in that, The handle-side conductive portion is positioned opposite the surface of the main body portion when the handle-side connecting portion and at least one housing-side connecting portion are connected. The at least one connector also has a force-applying component that applies force to cause the housing-side guide portion to protrude from the surface of the body portion toward the handle-side guide portion.

3. The power tool according to claim 2, characterized in that, The at least one connector further includes a plate component housed within the body portion and is conductive. The board component is electrically connected to the detection circuit. The force-applying component is conductive, is disposed on the plate component, and electrically connects the housing-side conductive portion and the plate component. The force-applying component is configured such that by applying force to the housing-side guide portion in a direction away from the plate component, the housing-side guide portion protrudes from the surface of the main body portion toward the handle-side guide portion.

4. The power tool according to any one of claims 1 to 3, characterized in that, The handle-side connection part is either externally threaded or internally threaded. The at least one housing-side connecting portion is an external or internal thread capable of engaging with the handle-side connecting portion. The handle-side guide portion has an annular shape that is arranged around the handle-side connecting portion when it is separated from the handle-side connecting portion.

5. The power tool according to any one of claims 1 to 4, characterized in that, The handle-side guide portion is positioned to be separated from the surface of the housing while the handle-side connecting portion and the at least one housing-side connecting portion are connected.

6. The power tool according to any one of claims 1 to 5, characterized in that, The at least one connector includes a plurality of connectors. The at least one housing-side connection portion includes multiple housing-side connection portions. The main body of each of the plurality of connectors is positioned at a location corresponding to the respective connecting portion on the housing side.

7. The power tool according to any one of claims 1 to 6, characterized in that, A portion of the housing-side conductive portion is housed within the main body portion. The main body has multiple through holes through which wires that electrically connect a portion of the housing-side conductive portion housed in the main body and the detection circuit can be inserted.

8. The power tool according to claim 7, characterized in that, The housing-side guide portion is a metal pin with a long shaft. The main body has a symmetrical shape that is symmetrical to the surface containing the long axis. The plurality of through holes includes two through holes, which are respectively disposed in two regions divided by a surface containing the long axis.

9. The power tool according to any one of claims 3 to 8, characterized in that, The handle-side conductive portion is positioned opposite the surface of the main body portion when the handle-side connecting portion and the at least one housing-side connecting portion are connected. The at least one connector also has a force-applying component that applies force to cause the housing-side guide portion to protrude from the surface of the main body portion toward the handle-side guide portion. The top of the conductive part on the housing side has a curved shape.

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