Electric tool

Abstract

The purpose of the present invention is to provide an electric power tool which allows the degree of increase in size thereof to be suppressed. An electric power tool (1) includes a motor (2), a plurality of switching elements (3), a cylindrical capacitor (4), a circuit board (5), and a housing (6). The circuit board (5) has the capacitor (4) mounted thereon and is fixed so as to overlap at least a portion of the motor (2) when viewed in an axial direction (D1) defined with respect to a rotation axis (211) of the motor (2). The circuit plate (5) has a plate-shaped base portion (51) and a plate-shaped protruding portion (52). The protruding portion (52) protrudes in a predetermined direction from an end portion of the base portion (51). The capacitor (4) is disposed on the protruding portion (52) so as to overlap with at least a part of the motor (2) when viewed in a protruding direction (D2), which is the predetermined direction.

Description

Technical Field

[0001] The present disclosure relates generally to power tools and, more particularly, to power tools including motors. Background Art

[0002] Patent document 1 discloses a controller for controlling a motor for an electric impact screwdriver. The controller for the motor includes an inverter circuit, a gate driver circuit, an operation circuit, a speed indication circuit, and a torque control switch. The inverter circuit outputs a drive signal to a brushless DC motor that drives an electric tool such as an electric screwdriver or an electric impact screwdriver. The gate driver circuit controls the inverter circuit. The operation circuit performs pulse width modulation (PWM) control on the gate driver circuit. The speed indication circuit outputs a speed indication signal to the operation circuit in response to a signal provided from a trigger switch for controlling the electric tool. The torque control switch defines a preset torque value for the motor to prevent the motor from rotating with a torque equal to or greater than the preset torque value. The operation circuit performs PWM control so that when the torque control switch is turned on, the motor does not rotate with a torque equal to or greater than the preset torque value.

[0003] The electric impact screwdriver disclosed in Patent Document 1 includes a capacitor in order to stabilize the voltage applied to a plurality of switching elements. However, generally speaking, the capacitor will be directly mounted on the circuit board. Therefore, when a cylindrical capacitor is introduced, the housing accommodating the capacitor will have an increased size. In other words, there is a problem of excessive enlargement of the electric tool.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-15986 Summary of the invention

[0007] An object of the present disclosure is to provide an electric power tool designed to suppress enlargement thereof.

[0008] An electric tool according to one aspect of the present disclosure includes a motor, a plurality of switching elements, a cylindrical capacitor, a circuit board, a housing, and a holding portion. The plurality of switching elements switch the current flowing through the motor. The capacitor stabilizes the voltage to be applied to the plurality of switching elements. The capacitor is mounted on the circuit board, and when viewed along an axial direction defined relative to the rotation axis of the motor, the circuit board is fixed to overlap with at least a portion of the motor. The housing accommodates the motor, the plurality of switching elements, the circuit board, and the capacitor inside. The holding portion holds the front end tool, and the rotational force is transmitted from the motor to the front end tool. The circuit board has a plate-shaped base and a plate-shaped protrusion. The protrusion protrudes from the end of the base in a predetermined direction. The capacitor is arranged on the protrusion in a manner that overlaps with at least a portion of the motor when viewed along the protruding direction, and the protruding direction is a predetermined direction along which the protrusion protrudes. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [ Figure 1 ] Figure 1 is a cross-sectional view of a main portion of an electric power tool according to an embodiment.

[0010] [ Figure 2 ] Figure 2 is a block diagram illustrating a schematic configuration of an electric power tool.

[0011] [ Figure 3 ] Figure 3 It is a cross-sectional view of the main parts of the power tool.

[0012] [ Figure 4 ] Figure 4 It is a perspective view illustrating the appearance of the electric tool. DETAILED DESCRIPTION

[0013] (Implementation Method)

[0014] (1) Summary

[0015] Now refer to Figures 1 to 3 An overview of an electric power tool 1 according to the exemplary embodiment will be described.

[0016] like Figure 1 and Figure 2 As shown, the electric tool 1 according to the present embodiment includes a motor 2, a plurality of switching elements 3, a cylindrical capacitor 4 (hereinafter referred to as "capacitor 4"), a circuit board 5, a housing 6, and a holding portion 72. The electric tool 1 is assumed to be an electric screwdriver used by an operator to perform a fastening operation including tightening a fastening member (such as a screw, a bolt, or a nut) into a work target (such as an electrical appliance or furniture). Alternatively, the electric tool 1 may also be an electric screwdriver used by an operator to perform a disassembly operation including loosening a fastening member from a work target.

[0017] The plurality of switching elements 3 switches the current flowing through the motor 2. The cylindrical capacitor 4 stabilizes the voltage to be applied to the plurality of switching elements 3. The capacitor 4 is arranged on the circuit board 5. The circuit board 5 is fixed to the housing 6 in such a manner as to overlap with at least a portion of the motor 2 when viewed along the axial direction D1 defined relative to the rotation axis of the motor 2. The housing 6 accommodates the motor 2, the circuit board 5, and the capacitor 4. The holding portion 72 holds the front end tool B1 to which the rotational force is transmitted from the motor 2.

[0018] like Figure 3 As shown, the circuit board 5 has a base 51 and a protruding portion 52. The base 51 has a plate shape. The protruding portion 52 also has a plate shape protruding from an end of the base 51 in a predetermined direction.

[0019] like Figure 1 As shown, the capacitor 4 is formed along the protruding direction D2 (reference Figure 3 ) is configured on the protrusion 52 in a manner that overlaps with at least a portion of the motor 2 when observed, and the protrusion direction D2 is a predetermined direction along which the protrusion 52 protrudes.

[0020] As can be seen from the above, the electric tool 1 according to the present embodiment allows the size of the housing 6 in the axial direction D1 to be reduced compared to an electric tool in which a capacitor is arranged on the circuit board so as not to overlap with the motor when viewed in the protruding direction D2. In other words, the electric tool 1 according to the present embodiment has the advantage of suppressing the degree of its enlargement. As a result, the electric tool 1 also has the advantage of improving the ease of operation of the electric tool 1 for an operator who performs a fastening or disassembly operation.

[0021] (2) Detailed structure

[0022] (2-1) Overall structure

[0023] Next, we will refer to Figures 1 to 4 A detailed configuration of the electric power tool 1 according to the present embodiment will be described.

[0024] like Figures 1 to 3 As shown, the electric tool 1 includes a motor 2, a switching element 3, a capacitor 4, a circuit board 5, a housing 6, a drive shaft 71, a holding portion 72, and a control unit 8. In addition to these components, the electric tool 1 also includes a plurality of fastening members 91, a signal line 92, a power line 93, a planetary gear mechanism 94, an operating member 95, and a battery terminal portion 96.

[0025] In the following description, Figure 1 As shown in FIG. 1 , the direction in which the motor 2 and the holder 72 are arranged in parallel will be defined as the “front-rear direction” herein. One direction from the motor 2 to the holder 72 is defined as the “forward direction” herein, and the other direction from the holder 72 to the motor 2 is defined as the “rearward direction” herein. In addition, in the following description, Figure 4 As shown, the direction in which the main body 61 (described later) and the grip portion 62 (described later) are arranged on top of each other is defined as the "upward direction" herein. One direction pointing from the grip portion 62 to the main body 61 is defined as the "upward direction" herein, and the other direction pointing from the main body 61 to the grip portion 62 is defined as the "downward direction" herein. In addition, the direction perpendicular to the front-back direction and the up-down direction is defined as the "left-right direction" herein. However, these definitions should not be interpreted as limiting the direction in which the power tool 1 should be used.

[0026] (2-2) Shell

[0027] The housing 6 accommodates the motor 2 , the capacitor 4 , the circuit board 5 , and at least a portion of the drive shaft 71 .

[0028] like Figure 4 As shown, the housing 6 has a body portion 61 , a grip portion 62 , and a battery attachment portion 63 .

[0029] (Main part)

[0030] like Figure 1 As shown, the main body 61 accommodates the motor 2 , the capacitor 4 , the circuit board 5 and at least a portion of the drive shaft 71 .

[0031] The main body 61 has a side portion 611 and two bottom portions 612a, 612b. The side portion 611 is cylindrical. More specifically, the side portion 611 is cylindrical. Each of the two bottom portions 612a and 612b is configured to cover a corresponding one of the openings formed in the front-to-back direction through the cylindrical side portion 611. In other words, the main body 61 is a bottomed cylinder. The two bottom portions 612a and 612b are disc-shaped. The thickness of the two bottom portions 612a and 612b is consistent with the front-to-back direction. The bottom portion 612a, which is one of the two bottom portions 612a and 612b, has a through hole 613. In the present embodiment, the through hole 613 is arranged to penetrate the central portion of the bottom portion 612a. The drive shaft 71 passes through the through hole 613.

[0032] (Handle)

[0033] The grip portion 62 protrudes from the body portion 61. More specifically, as Figure 4 As shown, the grip portion 62 protrudes downward from the body portion 61. The operator can perform operations such as tightening a screw by gripping the grip portion 62.

[0034] (Battery attachment section)

[0035] The battery attachment portion 63 is substantially in the shape of a rectangular parallelepiped. Figure 4 As shown, the battery attachment portion 63 is connected to the lower end portion of the grip portion 62. The rechargeable battery pack C1 (refer to Figure 2) is removably attached to the battery attachment portion 63. The power tool 1 is powered by a battery pack C1 as a power source. That is, the battery pack C1 is a power source that supplies power for driving the motor 2. The battery pack C1 is not a constituent element of the power tool 1. However, this should not be construed as restrictive. Alternatively, the power tool 1 may include the battery pack C1. The battery pack C1 includes an assembled battery formed by connecting a plurality of secondary batteries (such as lithium-ion batteries) in series and a housing in which the assembled battery is housed.

[0036] According to the present embodiment, the battery attachment portion 63 is provided with a battery terminal portion 96 (refer to Figure 2 The power line 93 electrically connects the battery terminal portion 96 to the power line connection portion 54 of the circuit board 5 (described later), and transmits the power supplied from the battery pack C1 to the motor 2 to the circuit board 5. The power transmitted to the circuit board 5 is supplied to the motor 2 via the plurality of switching elements 3.

[0037] (2-3) Motor

[0038] like Figure 1 As shown, the motor 2 is housed in the rear portion of the body portion 61. The motor 2 includes: a rotor 21, which includes a rotating shaft 211 and a permanent magnet; and a stator 22, which includes a plurality of coils. The axial direction D1 defined relative to the rotating shaft 211 is consistent with the front-to-back direction. Due to the electromagnetic interaction between the permanent magnet and the plurality of coils, the rotor 21 rotates relative to the stator 22. Specifically, the plurality of switching elements 3 switch the current flowing through each of the plurality of coils, thereby causing the rotor 21 to rotate relative to the stator 22 due to the electromagnetic interaction between the permanent magnet and the coils in which the current alternately flows.

[0039] In addition, the motor 2 is a servo motor. The torque and the rotation speed of the motor 2 are changed under the control of the control unit 8 (more specifically, the speed control section 82 described later of the control unit 8). More specifically, the control unit 8 controls the operation of the motor 2 by performing feedback control to control the torque and the rotation speed of the motor 2 to tend to their respective target values.

[0040] (2-4) Circuit board

[0041] The circuit board 5 is a board on which a plurality of electronic components for driving the motor 2 are mounted. As used herein, the “plurality of electronic components” includes a plurality of switching elements 3 and capacitors 4. That is, the plurality of switching elements 3 and capacitors 4 are mounted on the circuit board 5. In the present embodiment, the plurality of switching elements 3 and capacitors 4 are mounted on the front surface of the circuit board 5.

[0042] like Figure 1As shown, the circuit plate 5 is accommodated in the rear part of the main body 61. In the present embodiment, the circuit plate 5 is arranged behind the motor 2 in the axial direction D1. The circuit plate 5 is a plate member. When viewed along the axial direction D1, the circuit plate 5 is configured to overlap with at least a portion of the motor 2. In the present embodiment, the thickness of the circuit plate 5 is consistent with the axial direction D1 (front-rear direction).

[0043] The circuit board 5 has a base 51 and a protruding portion 52. The base 51 is plate-shaped. Figure 3 As shown, when viewed along the axial direction D1, the base 51 according to the present embodiment is a circle with the arc-shaped lower portion cut off. The protrusion 52 has a plate shape protruding in a predetermined direction from the end of the base 51. In the present embodiment, the protrusion 52 is a plate shape protruding in a downward direction from the lower end of the base 51. Figure 3 The protruding direction D2 shown is a predetermined direction in which the protrusion 52 protrudes. The protruding direction D2 according to the present embodiment is downward. When viewed along the axial direction D1, the protrusion 52 according to the present embodiment is an isosceles trapezoid whose width (dimension measured in the left-right direction) gradually decreases from top to bottom.

[0044] The plurality of fastening members 91 are used to fasten the base 51 to the housing 6. For example, each of the plurality of fastening members 91 is a fastening screw. The plurality of fastening members 91 are inserted into through holes (not shown) provided through the base 51 and screwed into corresponding screw holes of the housing to fix the base 51 to the housing 6.

[0045] like Figure 3 As shown, the number of the fastening members 91 according to the present embodiment is three. Two fastening members 91a of the three fastening members 91 are respectively inserted through the left and right sides of the lower end portion of the base 51. The two fastening members 91a are inserted so as to face each other in the left-right direction. The two fastening members 91a are located near the protrusion 52.

[0046] According to the present embodiment, two fastening members 91a are inserted through the lower left and lower right portions of the base 51, respectively. In other words, the two fastening members 91a are inserted through the outer edge portions at the lower end portion of the base 51. As used herein, the term "outer side" refers to a direction pointed away from the center of the base 51 as a reference point. The two fastening members 91a are inserted through the lower end portion of the base 51 in a manner as far away from each other as possible in the left-right direction. This configuration achieves the advantage of allowing the circuit board 5 to be fixed to the housing 6 more stably.

[0047] On the other hand, the remaining fastening member 91 b of the three fastening members 91 is inserted through the left-right middle portion at the upper end portion of the base 51 .

[0048] (Switching element)

[0049] The plurality of switch elements 3 switches the current flowing through the motor 2. More specifically, the plurality of switch elements 3 are provided one-to-one for the plurality of coils of the motor 2. Each of the plurality of switch elements 3 selectively allows current to flow through a corresponding one of the coils. Each of the plurality of switch elements 3 is, for example, a FET (field effect transistor) element. The circuit board 5 is a FET board.

[0050] The plurality of switch elements 3 according to the present embodiment are arranged on the same circuit board 5 as the capacitor 4. More specifically, the plurality of switch elements 3 are arranged on the base 51 of the circuit board 5. According to this configuration, the electric tool 1 does not need to be provided with an additional board other than the circuit board 5 to mount the plurality of switch elements 3 thereon. As a result, the electric tool 1 according to the present embodiment can be advantageously miniaturized compared to an electric tool including an additional board on which the plurality of switch elements 3 are arranged outside the circuit board 5.

[0051] (Capacitor)

[0052] Capacitor 4 stabilizes the voltage to be applied to the plurality of switching elements 3. More specifically, a cable electrically connecting a power line connection portion 54 (described later) and the plurality of switching elements 3 is arranged to pass through capacitor 4, thereby allowing capacitor 4 to stabilize the voltage to be applied to the plurality of switching elements 3.

[0053] The capacitor 4 according to the present embodiment is cylindrical. Generally speaking, a cylindrical capacitor tends to have a larger capacitance than a chip capacitor. Therefore, the cylindrical capacitor 4 further stabilizes the voltage to be applied to the plurality of switching elements 3.

[0054] The capacitor 4 is mounted on the circuit board 5 in such a manner that the axial direction defined with respect to the capacitor 4 coincides with the thickness (i.e., the front-rear direction) of the circuit board 5. In other words, the capacitor 4 is mounted on the circuit board 5 in such a manner that the radial direction defined with respect to the capacitor 4 coincides with the planar direction defined on the front surface of the circuit board 5. In the present embodiment, the capacitor 4 is a cylindrical capacitor, and therefore, has a larger size when measured along the thickness of the circuit board 5 than any other electronic component mounted on the circuit board 5.

[0055] like Figure 1As shown, the capacitor 4 is arranged on the protruding portion 52 in such a manner that the front portion of the capacitor 4 overlaps with the rear portion of the motor 2 when viewed in the protruding direction D2. In other words, the front portion of the capacitor 4 overlaps with the rear portion of the motor 2 when viewed in the protruding direction D2. According to this configuration, the electric tool 1 according to the present embodiment allows the size of the housing 6 in the axial direction D1 to be reduced compared to an electric tool in which a capacitor that does not overlap with the motor is arranged on the circuit board when viewed in the protruding direction D2. That is, the electric tool 1 according to the present embodiment has the advantage of suppressing the degree of enlargement. As a result, the electric tool 1 also has the advantage of improving the ease of operation of the electric tool 1 for an operator who performs a tightening or disassembly operation.

[0056] In addition, if Figure 3 As shown, when viewed in the protruding direction D2, the capacitor 4 is arranged between two fastening members 91a of the three fastening members 91. This configuration achieves the advantage of reducing the possibility that the stress caused to the circuit board 5 due to the vibration of the motor 2 is concentrated on one of the two fastening members 91a due to the load of the capacitor 4. As a result, this configuration achieves the advantage of improving the durability of the circuit board 5.

[0057] Note that preferably, the capacitor 4 is arranged on the protrusion 52 in such a manner that at least a portion of the capacitor 4 overlaps with the perpendicular bisector X1 of the line segment connecting the two fastening members 91a when viewed along the thickness of the base 51 (i.e., the front-to-back direction according to the present embodiment). This configuration achieves the advantage of substantially equally distributing the stress caused to the circuit board 5 by the vibration of the motor 2 to the two fastening members 91a. That is, this configuration achieves the advantage of more significantly improving the durability of the circuit board 5. As Figure 3 As used herein, “at least a portion of the capacitor 4 overlaps with the perpendicular bisector X1 of the line segment connecting the two fastening members 91 a ” means that the perpendicular bisector X1 passes through at least a portion of the capacitor 4 .

[0058] Note that, in order to achieve the advantage of reducing stress concentration, the perpendicular bisector X1 preferably passes through the center of gravity of the capacitor 4 when viewed along the thickness of the base 51. However, according to the present embodiment, due to design constraints on the electric tool 1, when viewed from the front of the base 51, as shown in FIG. Figure 3 As shown, the vertical bisector X1 passes through the left side portion of the center of gravity of the capacitor 4 .

[0059] (Signal line connection part and power line connection part)

[0060] The circuit board 5 includes a signal line connection portion 53 and a power line connection portion 54 .

[0061] The signal line connection portion 53 receives a signal line 92 (described later) connected to the signal line connection portion 53. The signal line connection portion 53 is electrically connected to the plurality of switch elements 3 via wiring provided on the circuit board 5. Therefore, the control signal transmitted to the signal line connection portion 53 through the signal line 92 is transmitted to the plurality of switch elements 3 via the wiring.

[0062] In the same manner, the power line connection portion 54 receives the power line 93 connected to the power line connection portion 54. The power line connection portion 54 is electrically connected to the plurality of switching elements 3 via the wiring provided on the circuit board 5. Therefore, the power transmitted to the power line connection portion 54 through the power line 93 is transmitted to the plurality of switching elements 3 via the wiring and the capacitor 4. Then, the plurality of switching elements 3 selectively supplies the power transmitted thereby to the plurality of coils of the motor 2 one by one.

[0063] like Figure 3 As shown, the signal line connection portion 53 and the power line connection portion 54 are arranged on both sides of the capacitor 4 on the protrusion 52. In other words, the signal line connection portion 53 and the power line connection portion 54 are arranged so that the capacitor 4 is interposed between them and adjacent to the capacitor 4 on both sides. This configuration achieves the advantage of suppressing the possibility of electromagnetic noise emitted from the power line 93 reaching the signal line 92, because the capacitor 4 allows the electromagnetic noise to be easily absorbed. As a result, this configuration achieves the advantage of suppressing the possibility of electromagnetic noise emitted from the power line 93 interfering with the function of the signal line 92 and causing inconvenience.

[0064] In the present embodiment, the signal line connection portion 53 and the power line connection portion 54 are configured to face each other in the left-right direction relative to the capacitor 4. When viewed from the front of the loop board 5, the signal line connection portion 53 is arranged on the left side of the capacitor 4 and the power line connection portion 54 is arranged on the right side of the capacitor 4. However, this should not be interpreted as restrictive. Alternatively, the signal line connection portion 53 may also be arranged on the right side of the capacitor 4 and the power line connection portion 54 may also be arranged on the left side of the capacitor 4.

[0065] (2-5) Drive shaft

[0066] The drive shaft 71 is connected to the rotation shaft 211 via the planetary gear mechanism 94. As a result, the drive shaft 71 rotates in synchronization with the rotation shaft 211 of the motor 2. That is, the drive shaft 71 is rotated by the motor 2.

[0067] The planetary gear mechanism 94 converts the rotation speed and torque of the rotating shaft 211 of the motor 2 into the rotation speed and torque required for the screwing operation. The planetary gear mechanism 94 is a speed reducer. The torque of the rotating shaft 211 of the motor 2 is transmitted to the drive shaft 71 via the planetary gear mechanism 94.

[0068] (2-6) Holding section

[0069] The holding portion 72 holds the tip tool B1, and the rotational force is transmitted to the tip tool B1 from the motor 2. The holding portion 72 is provided at the front end of the drive shaft 71. The motor 2 rotates the rotation shaft 71 together with the tip tool B1.

[0070] In this embodiment, the holding portion 72 is configured so that the tip tool B1 (refer to Figure 1 and Figure 2 ) is removably attached to the holding portion 72 via a chuck. However, this should not be interpreted as restrictive. Alternatively, the front tool B1 can also be directly removably attached to the holding portion 72 without using a chuck. Still alternatively, the front tool B1 can form an integral part of the holding portion 72. The front tool B1 is, for example, a screwdriver bit. Turning the front tool B1 engaged with the fastening member allows the operation of tightening or loosening the fastening member to be performed.

[0071] (2-7) Operation components

[0072] like Figure 4 As shown, the operating member 95 protrudes from the grip portion 62. The operating member 95 receives an operation command to control the rotation of the rotating shaft 211 of the motor 2. Pulling the operating member 95 allows the motor 2 to be selectively turned on and off. In addition, the rotation speed of the rotating shaft 211 can be adjusted according to how deep the operating member 95 is pulled. The deeper the operating member 95 is pulled, the higher the rotation speed of the rotating shaft 211 becomes.

[0073] (2-8) Control unit

[0074] like Figure 2 As shown, the control unit 8 includes a rotation control section 81 and a speed control section 82 .

[0075] The rotation control section 81 controls the plurality of switching elements 3 by selectively supplying power from the battery pack C1 to one of the plurality of coils of the motor 2, thereby controlling the rotation of the motor 2. The rotation control section 81 controls the plurality of switching elements 3 based on the rotation angle of the rotor 21. For example, the motor 2 includes a magnetic sensor (not shown) for detecting a magnetic field generated by a permanent magnet of the rotor 21. The rotation control section 81 controls the plurality of switching elements 3 based on the rotation angle of the rotor 21 calculated from the detection result of the magnetic sensor.

[0076] The rotation control unit 81 is connected to the signal line 92 (reference Figure 2 ) outputs a control signal indicating the control content to the plurality of switch elements 3 on the circuit board 5. The signal line 92 electrically connects the rotation control unit 81 and (the signal line connection portion 53 of) the circuit board 5, and transmits the control signal indicating the control content of the rotation control unit 81 to (the plurality of switch elements 3 of) the circuit board 5.

[0077] The speed control part 82 starts or stops the rotating shaft of the rotating motor 2 according to how deep the operation member 95 is pulled. In addition, the speed control part 82 also controls the rotating speed of the rotating shaft 211.

[0078] The speed control unit 82 includes, for example, a microcontroller. The speed control unit 82 can change the rotation speed of the drive shaft 71 and the front end tool B1 by changing the rotation speed of the rotation shaft 211. The speed control unit 82 is, for example, arranged on the power line 93 and changes the power supplied from the battery pack C1 to the motor 2 via the plurality of switch elements 3, thereby changing the rotation speed of the rotation shaft 211.

[0079] (3) Modification

[0080] Next, modifications of the exemplary embodiment will be listed one by one. Note that the modifications to be described below can be adopted in appropriate combination.

[0081] In the above embodiment, when viewed along the axial direction D1, the base 51 is a circle with the arc-shaped lower portion cut off. However, this should not be interpreted as restrictive. Alternatively, the base 51 may also have a rectangular, circular or elliptical shape. In other words, when viewed along the axial direction D1, the shape of the base 51 is not limited to any specific shape.

[0082] When viewed along the axial direction D1, the shape of the protrusion 52 is an isosceles trapezoid in the above embodiment, but may also be a rectangle or triangle whose width (i.e., the dimension measured in the left-right direction) gradually decreases from top to bottom. In other words, when viewed along the axial direction D1, the shape of the protrusion 52 is not limited to any specific shape.

[0083] Furthermore, in the above-described embodiment, the protrusion 52 has a plate shape that protrudes from the lower end of the base 51 in the downward direction. However, this should not be construed as restrictive. Alternatively, the protrusion 52 may also have a plate shape that protrudes from the upper end of the base 51 in the upward direction. Still alternatively, the protrusion 52 may also have a plate shape that protrudes from the left end of the base 51 in the left direction, or may also have a plate shape that protrudes from the right end of the base 51 in the right direction. In other words, the protruding direction D2 along which the protrusion 52 protrudes is the downward direction in the above-described embodiment, but may also be an upward, leftward, or rightward direction.

[0084] Note that the protrusion 52 may have a plate shape that protrudes obliquely from the lower left end (or lower right end, or upper left end, or upper right end) of the base 51 to the lower left (or obliquely to the lower right end, upper left end, or upper right end). In other words, the protruding direction D2 along which the protrusion 52 protrudes may be obliquely to the lower left (or obliquely to the lower right, or obliquely to the upper left, or obliquely to the upper right). That is, the protruding direction D2 along which the protrusion 52 protrudes may be any direction that intersects the axial direction D1 (i.e., the front-rear direction) defined relative to the rotation axis 211.

[0085] In addition, the protrusion 52 may have a plate shape that protrudes obliquely to the lower left or lower right from the lower end portion of the base 51 .

[0086] In the above embodiment, the number of the fastening members 91 is three. However, this should not be construed as limiting. The number of the fastening members 91 may be two or equal to or greater than four. In other words, the number of the fastening members 91 only needs to be equal to or greater than two.

[0087] In addition, in the above-described embodiment, each of the two fastening members 91a is inserted through the outer edge portion at the lower end portion of the base 51. Alternatively, each of the two fastening members 91a may also be inserted inside the outer edge portion at the lower end portion of the base 51. As used herein, "inside" refers to a direction pointing to the middle of a line segment defined relative to the base 51.

[0088] In addition, in the above-described embodiment, the two fastening members 91a are respectively inserted through the lower left end portion and the lower right end portion of the base 51. However, this should not be construed as restrictive. Alternatively, the left fastening member 91a of the two fastening members 91a may also be inserted through the right side portion of the lower left end portion of the base 51, and the right fastening member 91a may also be inserted through the left side portion of the lower right end portion of the base 51. That is, the two fastening members 91a do not have to be inserted through the lower end portion of the base 51 as far away from each other as possible in the left-right direction.

[0089] In the above embodiment, the two fastening members 91a are inserted to face each other in the left-right direction. However, the two fastening members 99a do not have to be inserted to face each other in the left-right direction. Alternatively, one of the two fastening members 91a may also be inserted through the lower portion of the base 51 instead of the other fastening member 91a.

[0090] In addition, in the above-described embodiment, each of the two fastening members 91a is inserted through the base 51. However, this should not be construed as limiting. Alternatively, each of the two fastening members 91a may also be inserted through the protrusion 52. For example, one of the two fastening members 91a may also be inserted through the left side portion of the protrusion 52, while the other fastening member 91a may also be inserted through the right side portion of the base 51. Conversely, one of the two fastening members 91a may also be inserted through the right side portion of the protrusion 52, while the other fastening member 91a may also be inserted through the left side portion of the base 51.

[0091] In the above embodiment, the plurality of switch elements 3 are mounted on the same circuit board 5 as the capacitor 4. However, this should not be construed as restrictive. Alternatively, the plurality of switch elements 3 may also be mounted on a different board provided separately from the circuit board 5. That is, the power tool 1 may include an additional board other than the circuit board 5 to mount the plurality of switch elements 3 on the additional board.

[0092] In the above embodiment, the capacitor 4 is a cylindrical capacitor (i.e., circular when viewed along an axial direction defined relative to the capacitor 4). However, this should not be construed as limiting. Alternatively, the capacitor 4 may also be a polygon (e.g., a quadrilateral or a pentagon) when viewed along an axial direction defined relative to the capacitor 4. Still alternatively, the capacitor 4 may also have a polygonal shape with rounded corners when viewed along an axial direction defined relative to the capacitor 4. That is, the shape of the capacitor 4 is not limited to any particular shape when viewed along an axial direction defined relative to the capacitor 4.

[0093] The above-mentioned power tool 1 is an electric screwdriver to be used by an operator to perform a fastening operation or a disassembly operation, wherein the fastening operation includes tightening a fastening member to a work target, and the disassembly operation includes loosening the fastening member from the work target. However, this should not be construed as restrictive. Alternatively, the power tool 1 may also be a drill, a hammer drill, a band saw, an electric cutter, an electric sander, or a disc grinder.

[0094] In addition, the electric tool 1 may also be an impact screwdriver or an impact wrench.

[0095] (Summary)

[0096] According to the first aspect, an electric tool (1) includes a motor (2), a plurality of switching elements (3), a cylindrical capacitor (4), a circuit board (5), a housing (6), and a holding portion (72). The plurality of switching elements (3) switch the current flowing through the motor (2). The capacitor (4) stabilizes the voltage to be applied to the plurality of switching elements (3). The circuit board (5) is mounted with the capacitor (4) and is fixed to overlap at least a portion of the motor (2) when viewed along an axial direction (D1) defined relative to a rotating shaft (211) of the motor (2). The housing (6) accommodates the motor (2), the plurality of switching elements (3), the circuit board (5), and the capacitor (4) inside. The holding portion (72) holds a front end tool (B1), and a rotational force is transmitted from the motor (2) to the front end tool (B1). The circuit board (5) has a plate-shaped base (51) and a plate-shaped protrusion (52). The protrusion (52) protrudes from the end of the base (51) in a predetermined direction. The capacitor (4) is arranged on the protruding portion (52) in such a manner as to overlap with at least a portion of the motor (2) when viewed along a protruding direction (D2), the protruding direction being a predetermined direction along which the protruding portion (52) protrudes.

[0097] This aspect has the advantage of suppressing the enlargement of the electric tool (1).

[0098] According to the second aspect of the electric tool (1) that can be implemented in conjunction with the first aspect, it also includes a plurality of fastening members (91). The plurality of fastening members (91) are used to fix the base (51) to the housing (6). When viewed along the protruding direction (D2), the capacitor (4) is located between two fastening members (91a) among the plurality of fastening members (91). The two fastening members (91a) are located closer to the protruding portion (52) than at least another fastening member (91) belonging to the plurality of fastening members (91).

[0099] This aspect achieves the advantage of improving the durability of the circuit board (5).

[0100] In an electric tool (1) according to a third aspect that can be implemented in conjunction with the second aspect, the capacitor (4) is arranged on the protrusion (52) in the following manner: when observed along the thickness of the base (51), at least a portion of the capacitor (4) overlaps with a perpendicular bisector (X1) of a line segment connecting two fastening members (91) together.

[0101] This aspect achieves the advantage of more significantly improving the durability of the circuit board (5).

[0102] In the electric tool (1) according to the fourth aspect which can be implemented in conjunction with any one of the first to third aspects, the plurality of switch elements (3) are mounted on the circuit board (5).

[0103] This aspect achieves the advantage of miniaturization of the electric tool (1).

[0104] According to the fifth aspect of the electric tool (1) that can be implemented in conjunction with the fourth aspect, it also includes a rotation control unit (81), a signal line (92) and a power line (93). The rotation control unit (81) controls multiple switching elements (3). The signal line (92) transmits a control signal indicating the control content of the rotation control unit (81) to the circuit board (5). The power line (93) transmits the power to be supplied to the motor (2) to the circuit board (5). The circuit board (5) also includes a signal line connection unit (53) and a power line connection unit (54). The signal line connection unit (53) receives the signal line (92) connected thereto. The power line connection unit (54) receives the power line (93) connected thereto. The signal line connection unit (53) and the power line connection unit (54) are arranged on both sides of the capacitor (4) on the protruding portion (52).

[0105] This aspect achieves the advantage of suppressing the possibility that electromagnetic noise emitted from the power supply line (93) interferes with the function of the signal line (92) and causes inconvenience.

[0106] Description of Reference Numerals

[0107] 1. Power Tools

[0108] 2 Motor

[0109] 21 rotor

[0110] 211 Rotation axis

[0111] 22 stator

[0112] 3 Switching elements

[0113] 4. Capacitors

[0114] 5-circuit board

[0115] 51 base

[0116] 52 protrusion

[0117] 53 signal line connection part

[0118] 54 Power cord connection

[0119] 6 Shell

[0120] 61 body part

[0121] 611 side

[0122] 612a, 612b bottom

[0123] 613 through hole

[0124] 62 Grip

[0125] 63 battery attachment part

[0126] 71 drive shaft

[0127] 72 holding part

[0128] 8Control Unit

[0129] 81 Rotation control unit

[0130] 82 speed control unit

[0131] 91 (91a) Fastening member

[0132] 92 signal line

[0133] 93 Power cord

[0134] 94 Planetary gear mechanism

[0135] 95 Operating components

[0136] 96 Battery terminal

[0137] B1 front-end tools

[0138] C1 Battery Pack

[0139] D1 Axial

[0140] D2 protrusion direction

[0141] X1 perpendicular bisector

Claims

1. An electric tool comprising: motor; a plurality of switching elements configured to switch current flowing through the motor; a capacitor configured to stabilize a voltage to be applied to the plurality of switching elements, the capacitor having a cylindrical shape; a circuit board on which the capacitor is mounted and fixed to overlap at least a portion of the motor when viewed in an axial direction defined relative to a rotation axis of the motor; a housing configured to house the motor, the plurality of switching elements, the circuit board, and the capacitor therein; and a holding portion configured to hold a front end tool to which a rotational force is transmitted from the motor; The circuit board comprises: a base having a plate shape; and a protrusion having a plate shape protruding from an end of the base in a predetermined direction, and The capacitor is arranged on the protruding portion so as to overlap with at least a portion of the motor when viewed in a protruding direction, which is a predetermined direction in which the protruding portion protrudes.

2. The electric power tool according to claim 1, further comprising a plurality of fastening members configured to fix the base to the housing, wherein When viewed in the protruding direction, the capacitor is between two fastening members among the plurality of fastening members, the two fastening members being located closer to the protruding portion than at least another fastening member belonging to the plurality of fastening members.

3. The electric tool according to claim 2, wherein: The capacitor is arranged on the protrusion in such a manner that at least a portion of the capacitor overlaps a perpendicular bisector of a line segment connecting the two fastening members together when viewed along the thickness of the base.

4. The electric tool according to any one of claims 1 to 3, wherein: The plurality of switch elements are mounted on the circuit board.

5. The electric tool according to claim 4, further comprising: a rotation control unit configured to control the plurality of switch elements; a signal line configured to transmit a control signal indicating control contents of the rotation control section to the circuit board; and a power line configured to transmit power to be supplied to the motor to the circuit board, wherein The circuit board also includes: a signal line connection portion configured to receive a signal line connected thereto; and a power cord connection portion configured to receive a power cord connected thereto, The signal line connection portion and the power line connection portion are arranged on both sides of the capacitor on the protruding portion.

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