JP2016087702A - Electric power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a heat radiation property of a switching element of an inverter circuit installed in an electric power tool.SOLUTION: An electric power tool, which drives a tip tool by a motor, includes an inverter circuit 61 for driving the motor. The inverter circuit 61 includes a plurality of high side switching elements Tr1, Tr3, Tr5, connected to an output terminal of a power supply on a positive electrode side and a plurality of low side switching elements Tr2, Tr4, Tr6. The high side switching elements are arranged on a common radiation fin 83, and the low side switching elements are respectively arranged on separate individual heat radiation fins 84.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electric tool in which a tip tool is driven by an electric motor.

  Examples of the electric tool configured to drive the tip tool using an electric motor as a driving source include a hammer, a hammer drill, a grinder, a bolt fastening machine, and the like. Hammers and hammer drills are also called striking tools, with a drill bit or anchor drill as the tip tool. These striking tools are used for applying an impact force to a work object by the tip tool or rotating the tip tool while applying the impact force. The grinder is a power tool for grinding a work object by rotating a grinding wheel as a tip tool, and is also called a disc grinder or disc sander. Examples of the electric tool that operates the work target by driving the tip tool include an impact driver, an impact wrench, and a cutter.

  Such electric tools include a type in which the electric motor is driven by the electric power of the secondary battery and a type in which the electric motor is driven by the electric power from the commercial power source. Some electric tools that change the rotational speed of the tip tool use a brushless motor as an electric motor. A power tool using a commercial power source has a rectifier for converting AC commercial current into direct current and an inverter circuit for driving an electric motor on the control board. The control board is installed in the housing of the power tool. Embedded in. The inverter circuit has a plurality of switching elements, and Patent Literature 1 describes a bolt fastening machine in which a control board is incorporated in a housing.

JP 2012-20363 A

  When a three-phase brushless motor or an induction motor is used as the electric motor, the inverter circuit has six switching elements. In the bolt fastening machine described in Patent Document 1, three switching elements and a rectifying element are attached to a U-shaped heat dissipation member. Other switching elements are directly attached to the control board, and no heat dissipation member is provided. In the heat dissipating member, a portion to which the switching element is attached and a portion to which the rectifying element is attached are parallel to each other, and both portions are connected by a connecting portion. The cooling air generated in the housing by the cooling fan collides with the connecting part to cool the heat dissipation member, and the cooling air is applied to the back side of the part where the switching element is attached and the part where the rectifying element is attached. Does not flow.

  For this reason, not only can the heat dissipation of the switching element not provided with the heat dissipation member be increased, but also the switching element at a position away from the connection part can increase the heat dissipation compared to the switching element close to the connection part. Can not.

  The objective of this invention is improving the heat dissipation of the switching element of the inverter circuit provided in an electric tool.

  The power tool of the present invention is connected to a plurality of high-side switching elements connected to the output terminal of the power supply on the positive electrode side and the output terminal of the power supply on the negative electrode side in the power tool that drives the tip tool with a motor. An inverter circuit for driving the motor, a plurality of low-side switching elements, a common radiating fin provided with the high-side switching element, and a plurality of individual radiating fins provided with the low-side switching element, respectively. And a control board on which is mounted.

  In the present invention, the heat generated from the switching element can be discharged to the outside by the radiation fin, and the heat dissipation of the switching element is improved.

It is sectional drawing which shows the impact tool which is an example of an electric tool. It is a block diagram which shows the motor control circuit of an electric tool. It is a front view which shows the surface of the control board shown by FIG. FIG. 4 is a right side view in FIG. 3. It is a perspective view which shows the arrangement | positioning form of the radiation fin shown by FIG. It is a front view which shows the display board in the display case shown by FIG. It is sectional drawing which shows the connection part of the electricity supply cable shown by FIG. It is sectional drawing which shows the principal part of the impact tool which is a modification. It is the sectional view on the AA line in FIG. It is sectional drawing which shows the principal part of the impact tool which is another modification. It is the BB sectional drawing in FIG. It is sectional drawing which shows the principal part of the impact tool which is another modification. It is CC sectional view taken on the line in FIG. It is sectional drawing which shows the principal part of the impact tool which is another modification. It is sectional drawing which shows the principal part of the impact tool which is another modification. It is the DD sectional view taken on the line in FIG. It is sectional drawing which shows the principal part of the impact tool which is another modification. It is the EE sectional view taken on the line in FIG. It is sectional drawing which shows the rear handle | steering-wheel of the impact tool which is another modification. It is the FF sectional view taken on the line in FIG. It is a top view which shows the grinder which is another example of an electric tool. It is a longitudinal cross-sectional view of FIG. It is an expanded sectional view which shows the inside of the base housing of a grinder. It is the GG sectional view taken on the line of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same code | symbol is attached | subjected to the common member.

  The electric tool shown in FIG. 1 is a striking tool 10a called a hammer drill, and a drill bit as a tip tool is detachably attached thereto. The drill bit, that is, the tip tool, is subjected to rotational motion and impact motion, and the impact tool 10a is used for drilling or the like using concrete or stone as a work object. The operation mode by the impact tool 10a includes an impact mode in which an impact force is applied to the tip tool and a rotation impact mode in which the tip tool is rotated in addition to the impact force.

  As shown in FIG. 1, the impact tool 10 a includes a cylinder 11, and a cylindrical tool holder 12 is attached to the tip of the cylinder 11. The cylinder 11 and the tool holder 12 are rotatably mounted in the cylinder housing 13a. When the cylinder 11 is rotated in a state where the tip tool is mounted on the tool holder 12, the tip tool is driven to rotate.

  A distal end portion of the hammer member 14 is incorporated in the proximal end portion of the tool holder 12 so as to be capable of reciprocating in the axial direction, and the proximal end portion of the hammer member 14 projects into the cylinder 11. A striker 15 for applying an impact force to the hammer member 14 is mounted in the cylinder 11 so as to be able to reciprocate in the axial direction, and a piston 16 can be reciprocated in the axial direction in the rear end portion of the cylinder 11. It is installed. An air chamber 17 is provided between the striker 15 and the piston 16, and when the piston 16 is driven forward, the air in the air chamber 17 is compressed and the striker 15 is driven in the forward direction. Thereby, the striker 15 collides with the hammer member 14, and the impact force of the striker 15 is applied to the tip tool via the hammer member 14.

  A tip cover 13b is attached to the tip of the cylinder housing 13a. A rubber tip cap 18 is attached to the tip of the tool holder 12. A detachable sleeve 19 is attached to the outside of the tip cap 18 so as to be reciprocally movable in the axial direction. A spring force in a direction away from the cylinder housing 13 a, that is, a forward direction is urged by the coil spring 21. . The tool holder 12 is provided with an engaging roller, that is, an engaging member 22 that engages with a groove provided in the tip tool so as to be movable in the radial direction. The detachable sleeve 19 is provided with a fastening ring 23, and as shown in FIG. 1, when the fastening ring 23 projects the engaging member 22 radially inward, the tip tool is fastened to the tool holder 12. . On the other hand, when the detachable sleeve 19 is moved backward against the spring force, the engagement between the fastening ring 23 and the engagement member 22 is released. Under this state, when the tip tool is pulled, the engaging member 22 is retracted radially outward, and the tip tool can be removed. On the other hand, when the tip tool is inserted into the tip portion of the tool holder 12 with the detachable sleeve 19 moved backward, and the tool holder 12 is moved forward by a spring force, the tip tool is moved to the tool holder 12. And is fastened by the engaging member 22.

  A gear housing 13c is provided at the rear end of the cylinder housing 13a, and a motor housing 13d is provided in the gear housing 13c. The motor housing 13d is oriented substantially perpendicular to the cylinder housing 13a, and the housing 13 of the impact tool 10a is formed by these housings 13a to 13d. The rear part of the housing 13 is covered with a cover 24, and the cover 24 constitutes a part of the housing 13. A rear handle 25 is provided so as to protrude rearward from the housing 13. The rear handle 25 has a main body portion 25a extending in a direction substantially perpendicular to the cylinder 11, and two leg portions 25b and 25c provided at both ends of the main body portion 25a. The upper leg portion 25b is integrated with the housing side, and the lower leg portion 25c is integrated with the lower end portion of the main body portion 25a, that is, the motor housing side.

  The respective leg portions 25 b and 25 c are attached to the back surface of the housing 13, and a grip space 26 is provided between the main body portion 25 a and the housing 13. A front handle 27 is provided at the front end of the housing 13. When an operator grips the main body portion 25a of the front handle 27 and the rear handle 25 and performs an operation such as drilling a work target with the impact tool 10a, the operator enters one hand into the gripping space 26. I will let you. The cover 24 forms a back wall of the housing 13 and faces the main body portion 25 a of the rear handle 25, and the inner surface of the main body portion 25 a faces the back side of the housing 13.

  When an operator performs an operation with the impact tool 10a, the operator usually moves the front leg 25b so that the cylinder housing 13a is above the motor housing 13d. The handle 27 and the rear handle 25 are gripped. The vertical relationship between the two legs 25b and 25c of the rear handle 25 and the vertical relationship between the cylinder housing 13a and the motor housing 13d indicate the posture in which the impact tool 10a is normally used, as shown in FIG. The cylinder housing 13a and the motor housing 13d are assembled via a gear housing 13c, and the gear housing 13c is formed by an upper side portion 28a on the cylinder housing 13a side and a lower side portion 28b on the motor housing 13d side.

  A brushless motor 31 is accommodated in the motor housing 13d. The brushless motor 31 has a cylindrical stator 32 around which a coil is wound, and a rotor 33 incorporated therein. The stator 32 and the rotor 33 are incorporated in a motor case 34. An output shaft 35 is attached to the rotor 33, and the output shaft 35 faces a direction substantially orthogonal to the reciprocating direction of the cylinder 11 and outputs the rotational driving force of the motor 31. The base end portion of the output shaft 35 is rotatably supported by a bearing 36a, and the output end portion of the output shaft 35 is rotatably supported by a bearing 36b. The bearing 36 a is incorporated in a retainer 37 disposed on the bottom wall portion of the motor housing 13 d, and the retainer 37 is covered with a bottom cover 38 attached to the housing 13. The bearing 36b is attached to the lower side portion 28b of the gear housing 13c. An upper cover 39 is attached to the upper surface of the rear side of the housing 13. The top cover 39 and the bottom cover 38 constitute part of the housing 13.

  In order to convert the rotational motion of the output shaft 35 of the motor 31 into the reciprocating motion of the piston 16, a crankshaft 41 is rotatably mounted on the gear housing 13c. The crankshaft 41 is substantially parallel to the output shaft 35 and is disposed on the rear end side of the housing 13 with respect to the output shaft 35, and a large-diameter pinion gear 42 provided on the crankshaft 41 is a tip of the output shaft 35. It meshes with a gear part provided in the part. An eccentric member 43 having a function as a crank weight is attached to the tip of the crankshaft 41, and a crankpin 44 is attached to the eccentric member 43 at a position eccentric from the rotation center of the crankshaft 41. One end of a connecting rod 45 is rotatably fitted to the crank pin 44 and the other end is fitted to a piston pin 46 attached to the piston 16 so as to be swingable. Thereby, the rotational motion of the crankshaft 41 driven by the output shaft 35 is converted into the reciprocating motion of the piston 16 in a direction substantially orthogonal to the output shaft 35 by the motion conversion mechanism 47 including the eccentric member 43 and the connecting rod 45. Is done. The eccentric member 43, the crank pin 44, and the like are covered with an upper cover 39.

  In order to transmit the rotational motion of the output shaft 35 to the rotational motion of the cylinder 11, a rotation transmission shaft 48 is rotatably supported in the gear housing 13c, and the rotation transmission shaft 48 includes a tip of the crankshaft 41. A large-diameter pinion gear 51 that meshes with the gear portion is provided. The rotational force of the output shaft 35 is transmitted to the rotation transmission shaft 48 by the motion conversion mechanism having such a gear. A driven sleeve 52 is fitted to the outside of the cylinder 11 so as to be movable in the axial direction. A drive-side bevel gear 53 provided at the distal end of the rotation transmission shaft 48 is provided at the base end of the driven sleeve 52. A meshing driven bevel gear 54 is provided. A key member is provided between the driven sleeve 52 and the cylinder 11. When the driven sleeve 52 is moved backward by a position where the driven bevel gear 54 meshes with the driving bevel gear 53, the driven sleeve 52 is moved by the key member. Engage with the cylinder 11. Thereby, the rotational motion of the output shaft 35 is transmitted to the rotational motion of the cylinder 11, and the impact tool 10a enters the rotational impact mode. On the other hand, when the driven sleeve 52 is moved forward, the engagement between the driven sleeve 52 and the cylinder 11 is released, the rotational force is not transmitted to the cylinder 11, and the impact tool 10a enters the impact mode.

  The brushless motor 31 of the impact tool 10 a uses a commercial power source as a power source, and a power supply cable 56 is attached to the rear handle 25. In FIG. 1, only a part of the power supply cable 56 is shown, and an outlet (not shown) is provided at the tip of the power supply cable 56. In order to switch between a state in which the motor 31 is driven and a state in which the motor 31 is stopped, a trigger lever, that is, a trigger switch 57 is provided in the main body 25 a of the rear handle 25.

  FIG. 2 is a block diagram showing a motor control circuit for controlling the rotation speed of the brushless motor 31. As shown in FIG. 2, the stator of the motor 31, that is, the stator 32, is provided with U-phase, V-phase, and W-phase windings, and the annular permanent magnet 33 a that rotates integrally with the rotor 33 includes In the circumferential direction, N-pole magnetic pole portions and S-pole magnetic pole portions are alternately formed. In order to detect the rotational position of the rotor 33, the motor control circuit has three Hall elements S1 to S3 corresponding to the three-phase windings as the rotational position detection sensor. Each of the Hall elements S1 to S3 is disposed to face the permanent magnet 33a, and when the polarity of the magnetic pole portion of the permanent magnet 33a becomes a neutral point between the N pole and the S pole by detecting the magnetic flux. It is a magnetic field detection element which outputs a detection signal to. The position of the rotor 33 is detected based on detection signals from the Hall elements S1 to S3, and a commutation operation for each winding, that is, an energization switching operation for the winding is performed. The rotational position detection sensor is not limited to the Hall element, but an electronic circuit having a comparator function and a Hall IC in which the Hall element is integrated into one chip may be used.

  The motor control circuit has an inverter circuit 61 for controlling the drive current for the U-phase, V-phase and W-phase windings. Electric power is supplied to the inverter circuit 61 from a rectifying element 63 for rectifying the alternating current of the commercial power supply 62 into a direct current. The rectifying element 63 is a diode bridge formed by connecting diodes in a bridge, and has a positive-side power source output terminal and a negative-side power source output terminal. A smoothing capacitor 64 is connected between the positive and negative output terminals of the rectifying element 63, and a diode 65 connected to the positive electrode side and a capacitor 66 connected to the negative electrode side are directly connected.

  The inverter circuit 61 is a three-phase full-bridge inverter circuit, and includes two switching elements Tr1, Tr2 connected in series, two switching elements Tr3, Tr4, and two switching elements Tr5, Tr6. Yes. The collectors of the three switching elements Tr1, Tr3, and Tr5 are connected to the output terminal on the positive side of the rectifying element 63. On the other hand, the emitters of the three switching elements Tr2, Tr4, and Tr6 are connected to the output terminal on the negative side of the rectifying element 63. Three switching elements Tr1, Tr3, Tr5 connected to the positive side of the rectifying element 63 are on the high side, and three switching elements Tr2, Tr4, Tr6 connected to the negative side are on the low side. ing. One connection terminal of the U-phase winding is connected between the emitter of the switching element Tr1 and the collector of the switching element Tr2. One connection terminal of the V-phase winding is connected between the emitter of the switching element Tr3 and the collector of the switching element Tr4. One connection terminal of the W-phase winding is connected between the emitter of the switching element Tr5 and the collector of the switching element Tr6. The other connection terminals of the U-phase, V-phase, and W-phase windings are connected to each other, and each winding is star-connected. In addition, as a connection system, it is good also as a delta connection. As each of the switching elements Tr1 to Tr6, an IGBT (insulated gate bipolar transistor) is used. For example, when a control signal is applied to the gates of the high-side switching element Tr1 and the low-side switching element Tr4, current is supplied to the U-phase and V-phase windings. The commutation operation for each winding is controlled by adjusting the timing of the control signal supplied to each switching element.

  The motor control unit 71 that calculates and outputs a control signal to the inverter circuit 61 includes a controller 72, and power is supplied to the controller 72 from a diode bridge, that is, a rectifying element 63. A control signal is sent from the controller 72 to the inverter circuit 61 via the control signal output circuit 73. Detection signals from the hall elements S1 to S3 as the rotational position detection sensors are sent to the rotor position detection circuit 74. The rotor position detection circuit 74 sends a signal to the motor rotation number detection circuit 75, and the motor rotation number detection circuit 75 outputs a signal corresponding to the motor rotation number to the controller 72. A detection signal corresponding to the motor current is sent from the motor current detection circuit 76 for detecting the current flowing through the motor 31 to the controller 72.

  A lighting signal is sent from the controller 72 to the energizing lamp 77 as a notification means. The energizing lamp 77 is lit when the outlet of the power supply cable 56 is inserted into the plug of the commercial power source. The controller 72 receives a signal from the operation switch 78 for setting the rotation speed of the motor 31. The motor rotation speed, that is, the rotation speed is controlled by adjusting the voltage supplied to each winding. Voltage control for the winding is performed by adjusting the duty ratio of the ON signal applied to the gates of the switching elements Tr1 to Tr6 of the inverter circuit 61 by PWM control of the switching elements. For example, when the duty ratio is set to 20%, a voltage of 20% of the output voltage from the rectifying element 63 is supplied to each winding, and when the duty ratio is set to 100%, the motor rotation speed becomes the maximum rotation speed. In order to display the set rotational speed, a speed display unit 79 is connected to the controller 72. When the trigger switch 57 is operated by an operator, an on / off detection signal is sent to the controller 72, and the motor 31 is driven to rotate at the rotation speed set by the operation of the operation switch 78. The controller 72 includes a microprocessor that calculates control signals, and a memory that stores control programs, arithmetic expressions, data, and the like.

  As shown in FIGS. 1, 3, and 4, a control board 81 is mounted in the housing 13, and an inverter circuit 61, a rectifying element 63, a motor control unit 71, and the like are mounted on the control board 81. The surface of the control board 81 faces the rear handle 25 (board case) and is accommodated in a tray 82. The tray 82 is substantially parallel to the output shaft 35 in the direction along the output shaft 35 on the radially outer side of the motor housing 13d. It is attached.

  As shown in FIG. 3, a common heat radiation fin 83 is mounted on the surface of the control board 81 in a direction along the longitudinal direction of the motor housing 13d. The common radiating fin 83 is provided with three switching elements Tr1, Tr3, Tr5 on the high side shown in FIG. Three individual radiating fins 84 are arranged in a line along the common radiating fin 83 and are directly attached to the surface of the control board 81. Each individual radiating fin 84 is provided with switching elements Tr2, Tr4, and Tr6 on the low side. The common radiating fin 83 and the three individual radiating fins 84 are each formed of a conductive material such as an aluminum alloy, and the individual radiating fins 84 and the common radiating fin 83 that are arranged in a row on the control board 81 are substantially parallel to each other. Be placed. The common radiating fins 83 are disposed inside the control board 81, and the individual radiating fins 84 are arranged close to one side of the control board 81 with respect to the common radiating fins 83.

  The high-side switching elements Tr1, Tr3, Tr5 are opposed to the individual radiating fins 84, and the individual radiating fins 84 are opposed to the switching elements Tr1, Tr3, Tr5 via a gap. The low-side switching elements Tr2, Tr4, and Tr6 are disposed on the side of the control board 81. The collectors of the switching elements Tr1, Tr3, Tr5 on the high side are connected to each other and electrically connected to the positive output terminal of the rectifying element 63. In the type in which the collector electrode is exposed on the side surface of the radiation fin, the collector is electrically connected to the common radiation fin 83. On the other hand, the collectors of the switching elements Tr2, Tr4, Tr6 on the low side are electrically connected to the emitters of the corresponding switching elements on the high side. Here, since each collector terminal of each switching element on the high side has the same potential, a common radiating fin 83 is used. On the other hand, since the collector terminals of the switching elements on the low side are not at the same potential, it is possible to improve the heat dissipation while achieving insulation by individually connecting the radiation fins 84 to the switching elements. Since the common heat radiating fin 83 is provided on the high side, the heat radiating area is increased and the heat radiating property can be improved. Furthermore, since it is not necessary to provide an insulating layer between the low-side heat dissipation fins 84 and the switching elements, heat dissipation can be improved.

  On the control board 81, a rectifier radiating fin 85 is disposed on the common radiating fin 83 on the lower end side in FIG. 3, and the rectifier radiating fin 85 is formed by a diode bridge. 63 is provided. The rectifier radiating fins 85 are arranged on the control board 81 so as to be closer to the other side of the control board 81 than the common radiating fins 83. In FIG. 3, the rectifier radiating fin 85 is inclined in a direction in which one end in the left-right direction approaches the common radiating fin 83 side and the other end separates from the common radiating fin 83. On the control board 81, capacitors 64 and 66 are arranged close to the side opposite to the inverter circuit 61.

  FIG. 5 shows an arrangement form of the common heat radiation fins 83, the individual heat radiation fins 84, and the rectifier heat radiation fins 85 with respect to the control board 81. As shown in FIG.

  As shown in FIGS. 1 and 4, a display case 86 is attached to the rear end portion of the housing 13 so as to face the rear handle 25. FIG. 6 is a front view showing the display substrate in the display case 86.

  The display case 86 includes a holder 86 a that houses the display substrate 87 and a display panel 86 b that is attached to the holder 86 a and covers the display substrate 87. As shown in FIG. 6, the display board 87 is provided with an energizing lamp 77, an operation switch 78, and speed display lamps 88a to 88d as speed display units. As shown in FIG. 3, the operation switch 78 is exposed on the display panel 86 b, and the rotation speed of the motor is input by the operation of the operation switch 78. One of the four speed display lamps 88a to 88d is turned on in accordance with the input rotation speed, and when the rotation speed is increased, the lighted speed display lamp is changed to 88a to 88d. The display panel 86b is provided with four windows 88 having transparency corresponding to the respective speed display lamps. A transparent window 77 a corresponding to the energizing lamp 77 is provided on the display panel 86 b.

  The operation switch 78 as the speed input means is a push button type, but may be a dial type instead of the button type. Furthermore, in addition to the energizing lamp 77, the display case 86 may be provided with an abnormal state display lamp that is turned on when the load applied to the tip tool exceeds a predetermined value.

  As shown in FIG. 3, a plurality of energization cables 67 are arranged on the surface side of the control board 81. Each winding and the inverter circuit 61 are connected by the energization cable 67, and signals from the hall elements S <b> 1 to S <b> 3 are output to the motor control unit 71.

  FIG. 7 is a cross-sectional view showing the connection portion 68 of the energization cable 67 shown in FIG. One energizing cable 67a has a lead wire 91b covered with a protective tube 91a, and a connector 92a provided on the other energizing cable 67b is provided with a plug 92b that meshes with the lead wire 91b. A crimping portion 92c is provided at the tip of the connector 92a, and the protective tube 91a of the energizing cable 67a is inserted into the crimping portion 92c. The crimped portion 92 c and the protective tube 91 a are covered with a heat shrinkable tube 93. As described above, the connecting portion 68 is caulked and the heat shrinkable tube 93 is provided in the connecting portion 68, so that the disconnection of the energizing cable 67 is prevented and the protective tube 91a is prevented from coming off. Even when the connecting portion 68 contacts the common heat dissipating fin 83 due to vibration during use of the impact tool 10a, the disconnection of the lead wire 91b is reliably prevented.

  As shown in FIG. 4, a cooling fan 95 for generating cooling air is provided at the tip of the output shaft 35 of the motor 31, and the cooling air flows inside the housing 13 by the cooling fan 95. . The cooling fan 95 is provided with the annular permanent magnet 33 a described above, and the permanent magnet 33 a rotates integrally with the rotor 33. A sensor substrate 97 is attached to the stator 32 via an insulator 96, and the above-described Hall elements S1 to S3 are provided on the sensor substrate 97. The position of the rotor 33 is detected based on detection signals from the hall elements S1 to S3.

  The bottom cover 38 constituting the housing 13 is provided with an intake port (not shown in FIG. 1), and the upper cover 39 is provided with an exhaust port (not shown). Therefore, when the motor 31 is driven, the cooling fan 95 generates cooling air that flows from the intake port and flows to the exhaust port in the housing 13. The cooling air flowing in from the air inlet flows through the cooling air passage formed between the gap between the rotor 33 and the stator 32 and between the motor case 34 and the stator 32 to cool the motor 31. A cooling air passage is also provided between the motor case 34 and the motor housing 13d. The cooling effect of the motor 31 is enhanced by the cooling air flowing through these cooling passages.

  As shown in FIG. 1, an air inlet 98 is provided in the bottom wall portion of the cover 24, and the cooling air flowing from the air inlet 98 by driving the cooling fan 95 is indicated by a dashed arrow in FIG. 3. Thus, it flows along the control board 81. The rectifier radiating fin 85 provided with the rectifying element 63 is disposed closer to the intake port 98 than the common radiating fin 83, and the rectifying element 63 and the rectifier radiating fin 85 are from the common radiating fin 83 and the individual radiating fin 84. Also, the cooling air flowing along the control board 81 first collides with the rectifier radiating fins 85 and cools the rectifying element 63 because it is disposed upstream of the cooling air. Next, the cooling air is branched into cooling air that flows along the common radiation fins 83 and cooling air that flows along the individual radiation fins 84 arranged in a row. Since the passage 99 through which the cooling air flows is formed by the gap between the individual radiating fin 84 and the switching element on the high side, the cooling air flowing through the passage 99 forms the switching element on the high side and the individual radiating fin 84. Cooling is ensured. Since the cooling air flows along the common radiating fins 83 and the individual radiating fins 84, the heat generated from each switching element is transferred in the thickness direction of the radiating fins and radiated to the outside from the radiating fins.

  FIG. 8 is a cross-sectional view showing a main part of a hitting tool 10b which is a modified example, and FIG. 9 is a cross-sectional view taken along line AA in FIG.

  In this striking tool 10b, the sensor substrate 97 is fixed to the stator 32. The cooling air generated by the cooling fan 95 flows from the air inlet 98 and is formed between the stator 32 and the rotor 33 and between the motor case 34 and the motor housing 13d, as indicated by broken lines. Flow through passage 101. As shown in FIG. 9, the tray 82 is fitted into a recess provided in the housing 13 and fixed to the housing 13, and the control board 81 accommodated in the tray 82 faces the motor 31 side. The common radiating fin 83 has a base portion 83a and a protruding portion 83b, and the protruding portion 83b is provided integrally with the base portion 83a. The protruding portion 83b is abutted against the protruding portion 102 provided on the motor housing 13d, and cooling air flows through the passage 103 defined by the protruding portion 83b and the protruding portion 102. Thus, when the protruding portion 83b is provided in the common radiating fin 83, the cooling air that flows in from the intake port 98 and flows along the base 83a, the protruding portion 83a, and the individual radiating fin 84 of the common radiating fin 83, The heat dissipation of the motor 31 and the switching element is further improved. As described above, the switching element on the high side is provided on the base 83a of the common radiating fin 83. Three individual radiating fins 84 are arranged in a row on the control board 81 so as to face the high-side switching elements, and each individual radiating fin 84 is provided with a low-side switching element.

  FIG. 10 is a cross-sectional view showing a main part of an impact tool 10c which is another modification, and FIG. 11 is a cross-sectional view taken along line BB in FIG.

  The basic structure of the impact tool 10c is the same as that of the impact tool 10b. However, as shown in FIG. 11, the protruding portion 83b of the common radiating fin 83 is not in contact with the motor housing 13d, and a passage 103 is formed by a gap between the motor housing 13d and the protruding portion 83b. The Even in such a form, the heat radiation of the motor 31 and the switching element is enhanced by the cooling air flowing along the common heat radiation fins 83 and the individual heat radiation fins 84. Unlike the impact tool 10b, the tray 82 of the impact tool 10c is fixed to the cover 24 by a screw member 104. Even in the form in which the tray 82 is screwed to the housing 13, the protruding portion 83b of the common heat radiation fin 83 may be abutted against the motor housing 13d.

  FIG. 12 is a cross-sectional view showing a main part of an impact tool 10d as another modification, and FIG. 13 is a cross-sectional view taken along the line CC in FIG.

  In the impact tool 10d, as shown in FIG. 13, a tray 82 is fixed to a holding portion 105 provided integrally with the motor housing 13d by a screw member 104. The control board 81 is provided on the tray 82 so as to face the rear of the impact tool 10d. Similar to the impact tool 10b, the motor housing 13d is provided with a protrusion 102, and the tray 82 is abutted against the protrusion 102, and a passage 103 is defined between the back surface of the tray 82 and the motor housing 13d. Is done. The common radiating fin 83 includes a base portion 83a on which three switching elements on the high side are provided and a protruding portion 83b. The common radiating fin 83 is formed in a substantially square cross section by a base portion 83a and a protruding portion 83b, and a contact portion 106 that contacts the tray 82 is provided in the protruding portion 83b. In the impact tool 10d, the housing 13 is further provided with an air inlet 98 that faces the control board 81. In addition to the cooling air that flows along the motor housing 13d, the housing 13 is substantially perpendicular to the control board 81. The heat radiation performance of the common heat radiation fins 83 and the individual heat radiation fins 84 is enhanced by the flowing cooling air.

  FIG. 14 is a cross-sectional view showing a main part of an impact tool 10e which is another modification. The basic structure of the impact tool 10e is the same as that of the impact tool 10c shown in FIGS. In the hitting tool 10c described above, the push button type operation switch 78 is provided on the display case 86 disposed in the housing 13, whereas the dial type operation switch, that is, the speed setting dial 78a is provided on the main body of the rear handle 25. It is provided in the part 25a.

  FIG. 15 is a cross-sectional view showing the main part of an impact tool 10f which is another modification, and FIG. 16 is a cross-sectional view taken along the line DD in FIG.

  In the impact tool 10 f, a control board 81 is disposed on the bottom cover 38 that constitutes a part of the housing 13. A speed setting dial 78 a is provided on the control board 81, and the speed setting dial 78 a is exposed on the side surface of the bottom cover 38. The common radiating fin 83 provided with the high-side switching element protrudes toward the bottom surface of the motor 31, and the three individual radiating fins 84 provided with the low-side switching element also protrude toward the bottom surface of the motor 31. . In addition to the air inlet 98, the bottom cover 38 is provided with a first air inlet 98 a that faces the common heat radiating fin 83, and a second air inlet 98 b that faces the individual heat radiating fin 84. Therefore, the cooling air flowing in from the respective intake ports 98, 98 a, 98 b collides with the common radiating fins 83 and the individual radiating fins 84, then changes the direction and flows toward the motor 31. Thereby, the heat dissipation of each switching element is improved.

  FIG. 17 is a cross-sectional view showing a main part of an impact tool 10g which is another modification, and FIG. 18 is a cross-sectional view taken along line EE in FIG.

  In the impact tool 10g, the control board 81 is disposed on the inner surface of the bottom cover 38 and the speed setting dial 78a is provided on the control board 81, similarly to the impact tool 10f shown in FIGS. In this impact tool 10g, Hall elements S1 to S3 as detection means for detecting the rotational position of the rotor 33 are attached to the control board 81, and the Hall elements S1 to S3 are the base end portions of the output shaft 35. An output signal is output to the rotor position detection circuit 74 shown in FIG. 2 in response to the sensor driving permanent magnet 33a provided on the rotor. Each of the permanent magnets 33a is provided in four in the same phase in the rotational direction so as to correspond to the four permanent magnets provided in the rotor 33. 17 and 18, only two of the four magnets and the three Hall elements S1 to S3 are shown. The common heat dissipating fins 83 and the individual heat dissipating fins 84 of the striking tool 10g have the same structure as that of the striking tool 10f shown in FIGS.

  19 is a cross-sectional view showing a rear handle of an impact tool 10h according to another modification, and FIG. 20 is a cross-sectional view taken along line FF in FIG.

  In this striking tool 10h, as shown in FIG. 20, a connecting fitting 111 is attached to the rear end of the housing 13, and a receiving fitting having a U-shaped cross section is formed inside the leg portion 25b of the rear handle 25. 112 is attached by a screw member 113. The receiving metal fitting 112 has a bottom wall portion 114 and side wall portions 115 integrated with both side portions thereof. The connecting fitting 111 is provided with a long hole 116 having a long diameter in the axial direction of the cylinder 11, that is, the striking axis direction. The long hole 116 is opened toward the receiving fitting 112 by a constricted portion 117. A cylindrical part 118 is provided in the receiving metal 112 so as to be movable in the long hole 116, and the cylindrical part 118 has a bottom wall of the receiving metal 112 by a connecting wall 119 having a width dimension smaller than the outer diameter. The unit 114 is integrated. A plurality of concave surfaces 121 are provided on both sides of the connecting metal fitting 111, and concave surfaces 122 are provided on the inner surface of the side wall 115 of the receiving metal fitting 112 so as to face the respective concave surfaces 121. A rubber elastic body 123 for absorbing vibration is incorporated between the concave surfaces facing each other, and a vibration isolating mechanism including the elastic body 123 is incorporated in the leg portion 25b.

  A similar receiving metal fitting 112 is also attached to the inside of the leg portion 25 c of the rear handle 25, and a connecting metal fitting 111 that is inserted into the receiving metal fitting 112 is attached to the rear end portion of the housing 13. Thus, both the leg portions 25b and 25c are connected to the housing 13 via the vibration isolation mechanism shown in FIG. Thereby, the vibration transmitted from the housing 13 to the rear handle 25 is absorbed by the elastic body 123, and the workability of the impact tool 10h can be improved.

  In each of the impact tools 10a to 10h described above, the cooling air is guided from the bottom side of the housing 13 toward the upper side of the housing 13, but the cooling air is guided in the opposite direction. It is good also as the form which did. In that case, the intake port becomes an exhaust port. As described above, the cooling air flow forms include a form in which the motor 31 flows from the proximal end side to the distal end side and a form in which the motor 31 flows from the distal end side toward the proximal end side. In addition to the intake port 98, when an intake port 98 as an air intake port is provided on the back side of the housing 13 as shown in FIG. The cooling air of the cooling fan 95 is sucked from the space 26 side, and the heat dissipation of the motor 31 and the switching element can be enhanced while making it difficult for dust to enter the inside.

  FIG. 21 is a plan view showing a grinder 10i as another example of the electric power tool, and FIG. 22 is a longitudinal sectional view of FIG. 23 is an enlarged cross-sectional view showing the inside of the base housing of the grinder, and FIG. 24 is a cross-sectional view taken along the line GG of FIG.

  The grinder 10i has a motor housing 13d in which the motor 31 is accommodated, and a base housing 13e is attached to the base end portion of the motor housing 13d. The motor housing 13d and the base housing 13e are each formed of an aluminum alloy, and the housing 13 of the grinder 10i is formed by both housings. As in the case described above, the motor 31 includes a cylindrical stator 32 around which a coil is wound, and a rotor 33 incorporated therein. An output shaft 35 is attached to the rotor 33, and the output shaft 35 outputs the rotational driving force of the motor 31.

  A grinding head, that is, a tool head 130 is detachably mounted on the tip of the motor housing 13d, and the tip of the output shaft 35 projects into the tool head 130. A rotation transmission shaft 131 is rotatably supported by a bearing 132 on the tool head 130 in a direction perpendicular to the output shaft 35, and a grinding wheel is mounted on the rotation transmission shaft 131 as a tip tool T. . The bearing 132 is attached to an annular retainer 133 attached to the front surface of the tool head 130. The front end portion of the output shaft 35 is supported by a bearing 134 attached to the tool head 130, and the rear end portion is supported by a bearing 135 attached to the motor housing 13d. In order to transmit the rotation of the output shaft 35 to the rotation transmission shaft 131, a drive-side bevel gear 136 is attached to the tip of the output shaft 35, and a driven bevel gear 137 with which the bevel gear 136 meshes is attached to the rotation transmission shaft 131. ing. When the motor 31 is driven, the rotation transmission shaft 131 is driven through the motion conversion mechanism 138 including the bevel gear 136 and the like, and the grinding wheel as the tip tool T is driven to rotate. The retainer 133 is provided with a grindstone cover 139 so as to cover the rear side of the tip tool T.

  A cooling fan 95 is provided at the tip of the output shaft 35, and cooling air is generated in the housing 13 by the cooling fan 95. The base housing 13e is provided with a plurality of intake ports 98a and 98b, and an exhaust port 129 is provided between the tip of the housing 13 and the tool head 130. Therefore, when the motor 31 is driven, cold air is generated in the housing 13 from the base portion side of the housing 13 toward the tip portion by the cooling fan 95 as indicated by a broken arrow.

  In the base housing 13e, as shown in FIGS. 23 and 24, a control board 81 is disposed adjacent to the motor housing 13d made of aluminum alloy, and the control board 81 includes a high-side switching element. Are disposed, and individual radiation fins 84 provided with low-side switching elements are arranged. The common heat radiation fin 83 has a base portion 83a and a protruding portion 83b. The protruding portion 83b has a butting wall 141 that extends in the lateral direction of the housing 13 and abuts against the motor housing 13d, and an extension 142 that extends from one end of the abutting wall 141 to the length of the housing 13. . As described above, the common heat radiation fin 83 has a U-shape as a whole, and the cooling space 140 is formed inside. A rectifying element 63 is attached to the extension 142.

  The control board 81 is provided on the tray 82, and the tray 82 extends in the longitudinal direction of the housing 13 and is fixed to the base housing 13e. The tray 82 has a bottom wall portion 82a and a side wall portion 82b integrated with the outer peripheral portion of the bottom wall portion 82a. The side wall portion 82b is provided with a ventilation port 143 so as to face the intake port 98a. A ventilation hole 144 is provided to face 98b. Therefore, when the cooling fan 95 is rotationally driven, outside air flows into the housing 13 from the intake ports 98a and 98b. The cooling air that has flowed into the tray 82 from the first air inlet 98a through the air vent 143 collides with the rectifying element 63 and cools it, and then the cooling space inside the U-shaped common radiating fin 83. The common radiating fin 83 is cooled by entering the inside 140. On the other hand, the cooling air flowing into the tray 82 from the second air inlet 98b through the air vent 144 collides with the individual radiating fins 84 and cools it. The cooling air after cooling each switching element flows along the control board 81, passes through the motor 31, and is discharged to the outside from the exhaust port 129.

  As shown in FIG. 23, the tray 82 having the function of a heat sink for heat dissipation is abutted against the motor housing 13d made of aluminum alloy, but a gap is provided between the tray 82 and the motor housing 13d. Also good.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the illustrated electric tool has a form in which a commercial power source is used as a power source, the present invention can also be applied to a battery-type electric tool that uses a battery case of a secondary battery in the housing 13 as a power source. The present invention can be applied not only to hammer drills and grinders but also to other power tools as long as the power tool is driven by a motor. The motor is not limited to a brushless motor, and may be an induction motor (induction motor).

10a to 10h ... impact tool, 10i ... grinder, 11 ... cylinder, 12 ... tool holder, 13 ... housing, 13a ... cylinder housing, 13b ... tip cover, 13c ... gear housing, 13d ... motor housing, 13e ... base housing, 14 ... hammer member, 15 ... striker, 16 ... piston, 17 ... air chamber, 18 ... tip cap, 19 ... removable sleeve, 23 ... fastening ring, 24 ... cover, 25 ... rear handle, 27 ... front handle, 31 ... Motor, 32 ... Stator, 33 ... Rotor, 33a ... Permanent magnet, 34 ... Motor case, 35 ... Output shaft, 38 ... Bottom cover, 39 ... Top cover, 41 ... Crankshaft, 42 ... Pinion gear, 43 ... Eccentric member, 47 ... motion conversion mechanism, 48 ... rotation transmission shaft, 56 ... feed cable, 57 ... trigger switch, 61 ... a Barter circuit, 63 ... rectifier element, 67 ... energizing cable, 68 ... connecting portion, 71 ... motor control unit, 72 ... controller, 77 ... energizing lamp, 78 ... operation switch, 81 ... control board, 82 ... tray, 83 ... common Radiation fin, 84 ... Individual radiation fin, 85 ... Radiation fin for rectifier, 86 ... Display case, 87 ... Display substrate, 95 ... Cooling fan, 96 ... Insulator, 97 ... Sensor substrate, 98 ... Intake port, 98a ... First Intake port, 98b ... second intake port, 99 ... passage, 101 ... passage, 129 ... exhaust port, 130 ... tool head, 131 ... rotation transmission shaft, 138 ... motion conversion mechanism, 140 ... cooling space, 141 ... but Wall, S1-S3 ... Hall element.

Claims (11)

In an electric tool that drives a tip tool with a motor,
An inverter circuit that has a plurality of high-side switching elements connected to an output terminal of a positive power supply and a plurality of low-side switching elements connected to an output terminal of a negative power supply, and drives the motor A control board having
A common radiating fin connected to the switching element on the high side, and a plurality of individual radiating fins connected to the switching element on the low side,
A power tool having   The power tool according to claim 1, further comprising a rectifying element that rectifies alternating current of a commercial power source into direct current and supplies power to the inverter circuit.   A cooling fan that is driven by the motor and generates cooling air in the housing has a plurality of the individual radiating fins arranged in a row, and the common radiating fins and the row of the individual radiating fins are substantially parallel to each other. The electric tool according to claim 1, wherein the electric power tool is arranged and causes cooling air generated by the cooling fan to flow along the common radiating fin and the individual radiating fin.   4. The electric motor according to claim 3, wherein the rectifying element is disposed upstream of the common radiating fin and the individual radiating fin, and the cooling air colliding with the rectifying element is guided toward the common radiating fin and the individual radiating fin. tool.   The common radiating fin is arranged inside the control board, the individual radiating fin is arranged close to one side of the control board toward the switching element on the high side, the switching element on the high side, and The power tool according to claim 3 or 4, wherein a passage through which cooling air flows is formed between the individual radiating fins.   The control board is disposed on the radially outer side of the motor housing that houses the motor, and the cooling air that is substantially parallel to the cooling air flowing along the motor housing is guided toward the common radiating fins and the individual radiating fins. The electric tool according to any one of claims 3 to 5.   The control board is disposed on the bottom side of a motor housing that houses the motor, and the cooling air that flows toward the motor housing is guided toward the common radiating fins and the individual radiating fins. The power tool according to any one of claims.   The power tool according to claim 7, comprising: a first air inlet that supplies cooling air toward the common radiating fin; and a second air inlet that supplies cooling air toward the individual radiating fin.   The rectifying element is provided, and an extension portion extending substantially parallel to the common radiating fin is provided integrally with the common radiating fin, the rectifying element is provided in the extension portion, and the cooling air flowing from the first air inlet is The power tool according to claim 8, wherein the power tool is supplied into a cooling space formed by the common heat radiation fin. In an electric tool that drives a tip tool with a motor,
An inverter circuit that has a plurality of high-side switching elements connected to an output terminal of a positive power supply and a plurality of low-side switching elements connected to an output terminal of a negative power supply, and drives the motor When,
A radiation fin directly connected to each of the plurality of switching elements on the low side;
A power tool having A common radiating fin connected across the switching element on the high side;
The electric tool according to claim 10, comprising:

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