JP6417250B2 - Electric tool - Google Patents

Description

  The present invention relates to an electric tool equipped with a DC brushless motor as a drive source.

  In recent years, this type of electric tool uses a DC brushless motor as disclosed in Patent Document 1 below as a drive source in order to make the tool body compact in the machine direction or improve its maintainability. Is provided. The DC brushless motor includes a rotor having a magnet (permanent magnet), a stator having a drive coil, a sensor board having a magnetic sensor for detecting the position of the magnetic pole of the rotor, and a rotor detected by the sensor board. It is equipped with an electric circuit board that detects the position of the magnetic poles of the stator and rotates the rotor by sequentially passing a current to each drive coil of the stator, and does not require a brush and a commutator. Compact and maintenance-free can be achieved.

JP 2005-160196 A

  However, it has been necessary to further reduce the length of the electric tool that uses a DC brushless motor as a drive source.

  An object of the present invention is to improve the workability and operability by further reducing the size of a power tool equipped with a DC brushless motor as a drive source in the machine length direction.

  Said subject is solved by each following invention. 1st invention is the electric tool which equipped the main body case with the DC brushless motor. In the first invention, the DC brushless motor has a stator supported by the main body case, a rotor rotatably supported on the inner peripheral side of the stator via the motor shaft, and a rotational position of the rotor. And a sensor substrate disposed opposite to the end face of the stator. 1st invention is an electric tool which has arrange | positioned the bearing which rotates and supports a motor shaft in the inner peripheral side of a sensor board | substrate in the DC brushless motor which concerns.

  According to the first aspect of the present invention, the bearing for rotating and supporting the motor shaft of the rotor is disposed on the inner peripheral side of the sensor substrate and is disposed so as to overlap in the motor shaft direction. For this reason, the DC brushless motor and the tool main body are made compact in the motor axial direction (machine length direction) by an amount corresponding to the overlap of the configuration in which the bearing is shifted from the sensor substrate in the motor axial direction. Can do. Thereby, workability | operativity and operativity (usability) of the said electric tool can be improved more.

  The second invention is an electric tool in which a DC brushless motor is housed in a main body case. In the second invention, the DC brushless motor has a stator supported by the main body case, a rotor rotatably supported on the inner peripheral side of the stator via the motor shaft, and a rotational position of the rotor. And a sensor substrate disposed opposite to the end face of the stator. According to a second aspect of the present invention, in the DC brushless motor, the sensor board includes a switching element, and the power tool is arranged such that a bearing that rotates and supports the motor shaft at a position in the motor axis direction is overlapped with the switching element.

  According to the second aspect of the present invention, the bearing for rotating and supporting the motor shaft of the rotor is arranged in a state of being overlapped with the switching element of the sensor board. For this reason, the DC brushless motor and the tool main body are made compact in the motor axial direction (machine length direction) by an amount corresponding to the overlap of the configuration in which the bearing is shifted with respect to the switching element in the motor axial direction. Can do.

  According to a third invention, in the first or second invention, the main body case has a half-splitting structure that can be split in half along the motor axis, and a screw tightening portion that couples the half-cases to each other Is a power tool set in a region on the output side (front side) of the sensor substrate.

  According to the third invention, the screws for mutually connecting the half cases of the main body case are tightened in the region in front of the sensor substrate. Therefore, it is not necessary to provide a screw hole or screw boss part in which the screw is tightened in the area on the rear side of the sensor board of the main body case, and the main body case and the tool main body part in the machine length direction can be made compact accordingly. Can be achieved.

  A fourth invention is the electric tool according to any one of the first to third inventions, wherein all the wirings to the sensor substrate are connected to the front surface of the sensor substrate.

  According to the fourth invention, it is not necessary to secure a space for wiring in a region behind the sensor substrate, and the main body case and thus the tool main body can be made compact in the length direction.

  A fifth invention is an electric tool according to any one of the first to fourth inventions, wherein a rear portion of the main body case is closed by a rear case, and a sensor board is disposed facing the rear case. . In the fifth invention, a cooling air flow path is set between the rear case and the sensor substrate.

  According to the fifth aspect, since the motor cooling air flows between the sensor board and the rear case behind the sensor board, the sensor board can be efficiently cooled.

  A sixth invention is the electric tool according to the fifth invention, wherein the rear case is provided with an air inlet.

  In the sixth aspect of the invention, the sensor substrate is cooled more efficiently by the outside air immediately after being introduced from the intake port.

  According to a seventh invention, in any one of the first to sixth inventions, a cooling fan is supported on the motor shaft between a bearing and a rotor for rotating and supporting the motor shaft, and the position in the motor axial direction Is a power tool in which the cooling fan is overlapped on the inner peripheral side of the stator.

  According to the seventh aspect of the present invention, the DC brushless motor and thus the tool body can be further reduced in the length direction by the amount that the cooling fan is overlapped with the stator.

It is a whole perspective view of the electric tool concerning this embodiment. This figure has shown the state seen from the front diagonal right side. It is a whole perspective view of the electric tool concerning this embodiment. This figure has shown the state seen from back diagonally right side. It is a longitudinal cross-sectional view of the electric tool which concerns on this embodiment. It is a longitudinal cross-sectional view of a tool main-body part. It is the (V)-(V) sectional view taken on the line of FIG. FIG. 4 is a cross-sectional view taken along line (VI)-(VI) in FIG. 3, and is a cross-sectional view of the tool body.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 shows an electric tool 1 having a DC brushless motor 20 according to the present embodiment as a drive source. In this example, as an example of the electric tool 1, a so-called impact type screw tightening machine (impact driver) is shown. In the following description, with respect to the front-rear direction of the electric power tool 1, the output side (tip tool side) is the front side, and the front side as viewed from the user is the rear side. Further, the horizontal direction is used based on the user who holds the grip portion.

  The electric power tool 1 includes a tool main body 10 and a grip 15 provided to protrude downward from the lower surface of the tool main body 10. The tool body 10 includes a substantially cylindrical body case 11. The rear surface side of the main body case 11 is closed by the rear case 12. The rear case 12 is fixed in a state of closing the rear surface side of the main body case 11 with two screws 13.

  The grip portion 15 is a portion that is gripped when the user uses the electric power tool 1, and a trigger-type switch lever 16 that is pulled by the user with a fingertip is provided at the upper front portion of the grip portion 15. When the switch lever 16 is pulled, the main switch 18 accommodated in the grip portion 15 is turned on to activate the DC brushless motor 20 as a drive source.

  The main body case 11 and the grip portion 15 have a halved structure in which left and right halved cases joined at a mating surface indicated by a symbol J in FIG. The halved structure mating surface J extends along the axial direction of the motor shaft 24. The main body case 11 and the grip portion 15 have a halved structure that can be divided into right and left by the mating surface J. The half structure of the main body case 11 and the grip portion 15 is coupled to each other by a total of eight screws 2.

  A battery attachment portion 17 for attaching a battery pack 40 as a power source of the electric tool 1 is provided at the lower portion of the grip portion 15. The battery mounting portion 17 is provided so as to mainly protrude forward (right side in FIG. 1). The battery pack 40 is mounted on the lower surface side of the battery mounting portion 17.

  As shown in FIG. 3, a DC brushless motor 20, a planetary gear mechanism 30, a drive shaft 31, a rotary striking mechanism 32, and an anvil 33 are accommodated in the main body case 11 in order from the rear side. The rotational output of the DC brushless motor 20 is transmitted to the anvil 33 through the planetary gear mechanism 30 and the rotary impact mechanism 32.

  The rotary hitting mechanism 32 has a function of converting the rotation of the drive shaft 31 into a rotary hitting operation with respect to the anvil 33. The hammer 32a is coaxially rotated with respect to the drive shaft 31 and supported so as to be axially movable. A compression spring 32b that biases the hammer 32a toward the tip side and a steel ball 32c that restricts the axial movement and rotation of the hammer 32a are provided.

  The anvil 33 is coaxially supported at the tip of the drive shaft 31 so as to be relatively rotatable. The shaft portion (output shaft 36) of the anvil 33 is supported by a cylindrical bearing 34 so as to be rotatable about the axis with respect to the distal end portion of the main body case 11.

  After the start of screw tightening, at the stage where the screw tightening resistance is small, the anvil 33 rotates in the screw tightening direction integrally with the drive shaft 31 via the rotary impact mechanism 32. When the screw tightening proceeds and the screw tightening resistance exceeds the rotational force transmitted to the drive shaft 31, the hammer 32a moves backward in the axial direction while rotating relative to the drive shaft 31 against the compression spring 32b. When the hammer 32a moves backward against the compression spring 32b, the engagement state with the anvil 33 is released. For this reason, the hammer 32a rotates while moving forward by the urging force of the compression spring 32b, and strikes the anvil 33 in the screw tightening direction. A chuck portion 35 for mounting a tip tool (not shown) such as a driver bit or a socket bit is provided at the tip portion of the output shaft 36 protruding from the front portion of the main body case 11.

  As shown in FIGS. 3 and 4, the DC brushless motor 20 is supported by a stator 21 fixed to the inside of the main body case 11 and rotatably on the inner peripheral side of the stator 21 via a motor shaft 24. A rotor 22 is provided. The stator 21 is obtained by winding a drive coil 21c around a stator core 21a via an electrical insulating member (insulator) 21b, and is fixed to the inner peripheral side of the main body case 11 so as not to move. Although omitted in the figure, recesses are provided at four locations in the circumferential direction of the inner surface of the main body case 11, projections are provided at four locations in the circumferential direction of the outer surface of the stator core, and each projection enters the recess of the main body case 11. By doing so, the stator 21 can be fixed in a state of being positioned (stopped) in the circumferential direction with respect to the main body case 11. The four protrusions of the stator core are arranged in the circumferential direction with two screws 13 for fixing the rear case 12 to the main body case 11 by arranging two on the right half and two on the left half. Can be set between the right and left projections. Thereby, the size (thickness) of the radial direction of the tool main-body part 10 can be made compact. Further, by arranging two set screws 23a for fixing the sensor substrate 23 to the electric insulating member 21b on the right half circumference and two on the left half circumference, the screw 13 is tightened at the right two positions. By setting between the set screws 23a and the two set screws 23a on the left side, the tool body 10 can be made more compact in the radial direction.

  The rotor 22 is obtained by attaching a magnet 22b to a rotor core 22a in which thin steel plates are laminated, and is rotatably supported via a motor shaft 24 fixed at the center thereof. The motor shaft 24 is rotatably supported around its axis via two front and rear bearings 25 and 26. Ball bearings (ball bearings) are used for the bearings 25 and 26, respectively. The front bearing 25 is held by an intermediate partition wall 27 that partitions the main body case 11 forward and backward. The inside of the main body case 11 is partitioned by the intermediate partition wall 27 into the DC brushless motor 20 side (rear side) and the rotary impact mechanism 32 side (front side).

  A cooling fan 28 is mounted on the motor shaft 24 between the intermediate partition wall 27 and the rotor 22. A so-called axial fan is used as the cooling fan 28. The rear bearing 26 is held by a bearing holding portion 12 a provided on the inner surface of the rear case 12.

  A sensor substrate 23 having a magnetic sensor for detecting the rotational position of the rotor 22 is disposed behind the stator 21. The sensor substrate 23 has a substantially disk shape and is disposed in a state of facing the rear end surface of the stator 21. Three magnetic sensors are arranged on the front surface of the sensor substrate 23. The rotation of the rotor 22 can be detected by this magnetic sensor. A total of six switching elements 29 are arranged on the rear surface of the sensor substrate 23. Resin is arrange | positioned so that each of the six switching elements 29 may be covered. An adhesive can be used as this resin. The rear part of this resin or adhesive may be in contact with the rear case 12. By covering the switching element 29 with resin or adhesive, damage due to vibration or the like can be prevented in advance, and durability of the electric power tool can be improved. The inner peripheral hole 23b of the sensor substrate 23 is formed as a large-diameter circular hole. As shown in the drawing, the rear bearing 26 and the bearing holding portion 12a enter the inner peripheral hole 23b of the sensor substrate 23.

  As shown in FIGS. 4 and 5, the sensor substrate 23 is coupled along the rear surface of the electrical insulating member 21 b of the stator 21. The sensor substrate 23 is screwed at three positions in the circumferential direction by three set screws 23a.

  The rear case 12 is provided with a plurality of air inlets 12b. The air inlet 12b is provided on the left and right side portions and the rear surface of the rear case 12. A plurality of exhaust ports 11 a are provided on the left and right sides of the main body case 11. When the cooling fan 28 is rotated by the activation of the DC brushless motor 20, outside air is introduced from the intake port 12b. When the introduced outside air flows to the front side, the sensor substrate 23, the stator 21, the rotor 22 and the like are cooled. The motor cooling air is exhausted from the exhaust port 11a. The air inlet 12 b may be provided in the main body case 11. Thereby, more outside air can be introduced into the main body case 11. Further, the air inlet provided in the rear surface of the rear case 12 may be provided in a state of extending in the lateral direction on the upper side and the lower side of the bearing 26.

  In particular, since the air inlet 12b is provided around the sensor substrate 23, the switching element 29 is efficiently cooled. Since the outside air sucked into the main body case 11 from the air inlet 12b flows forward through the inner peripheral hole 23b of the sensor board 23 while cooling the switching element 29 and the like, the sensor board 23 is driven by the motor cooling air. It is disposed in the middle of the inflow path, and the switching element 29 and the like are efficiently cooled also in this respect.

  As described above, the main body case 11 and the grip portion 15 have an integral halved structure and are coupled to each other by a total of eight screws 2. As shown in FIGS. 3 and 4, of the total four screws 2 that mutually join the half structure of the main body case 11, the rearmost screw 2 is tightened in front of the sensor substrate 23. It has become. Since the screw boss part and screw hole into which the screw 2 is tightened are arranged on the front side of the sensor substrate 23, the machine length L of the tool main body part 10 becomes compact as compared with the configuration arranged on the rear side. Yes. Further, since the screws 2 are tightened in the vicinity of the sensor substrate 23, the half cases are difficult to separate from each other, so that the relative displacement of the sensor substrate 23 with respect to the main body case 11 can be prevented more reliably. As a result, the detection accuracy of the sensor substrate 23 can be maintained or improved.

  A lighting tool 5 is provided at the front part of the tool body 10. An LED (light emitting diode) is used for the illumination tool 5. The illumination tool 5 is covered with a transparent cover 5a. The working part is brightly illuminated by the illuminator 5 to facilitate work in a dark place.

  A changeover switch 6 for switching the rotation direction of the output shaft 36 is disposed on the lower surface side of the tool main body 10 and at the base of the grip portion 15. By switching the changeover switch 6 to the left or right, the output shaft 36 can be rotated in the screw tightening direction or the screw loosening direction.

  A loop-shaped strap 3 is attached to the rear portion of the battery attachment portion 17. The strap 3 is coupled by a screw 2 on the rear side of the two screws 2 that couple the left and right halved structures of the grip portion 15 at the battery attachment portion 17. By passing the wrist through the strap 3, it is possible to prevent the electric tool 1 from being accidentally dropped. Further, as shown in FIG. 5, a belt hooking hook 4 is provided on the left side of the battery mounting portion 17. By hooking the hook 4 on the user's waist belt, the electric tool 1 can be carried in an upside down posture.

  As shown in FIG. 3, the battery attachment portion 17 accommodates a controller 7 including a motor control circuit, a power supply circuit, and the like. A capacitor 7 a is mounted on the upper surface of the controller 7. On the lower surface side of the controller 7, positive and negative connection terminals for electrically connecting the battery pack 40 are provided. The two power supply wires connected to the positive and negative connection terminals are drawn upward, wired in the grip portion 15, and connected to the sensor substrate 23. The lower part of the sensor substrate 23 projects outward from the stator 21, and two power lines are connected to the front surface of the projecting part.

  The battery pack 40 can be attached to the battery attachment portion 17 by sliding the battery pack 40 from the front side to the rear side with respect to the lower surface of the battery attachment portion 17. The battery pack 40 is, for example, a lithium ion battery with an output voltage of 18 V specifications, and can be repeatedly used by being removed and charged with a separately prepared charger.

  A display unit 19 for displaying other information such as the remaining capacity of the battery pack 40, the operating state of the tool main body unit 10, the on / off state of the lighting fixture 5, and the like is provided on the upper surface of the battery mounting unit 17.

  An elastomer resin layer 8 is provided on the surfaces of the main body case 11, the rear case 12, the grip portion 15, and the battery attachment portion 17. The elastomer resin layer 8 is used to reduce impact and prevent slipping when dropped.

  According to the electric tool 1 of the present embodiment configured as described above, the rear bearing 26 that rotatably supports the motor shaft 24 of the rotor 22 is disposed in the inner peripheral hole 23b of the sensor substrate 23, and the bearing 26 is overlapped with the sensor substrate 23 in the axial direction of the motor shaft 24 (motor axial direction). For this reason, the DC brushless motor 20 and the tool body 10 are moved in the motor axis direction (machine length L direction) by an amount corresponding to the overlap of the bearing 26 with respect to the configuration in which the bearing 26 is shifted from the sensor board 23 in the motor axis direction. Can be made compact.

  Further, according to the present embodiment, the rear bearing 26 that rotatably supports the motor shaft 24 is disposed in a state of overlapping the switching element 29 mounted on the rear surface of the sensor substrate 23 in the motor axial direction. For this reason, the DC brushless motor 20 and thus the tool main body 10 are moved in the motor axial direction (machine length) by the amount of overlap compared to the configuration in which the rear bearing 26 is displaced with respect to the switching element 29 in the motor axial direction. (L direction) can be made compact.

  Furthermore, according to the present embodiment, the screw 2 that couples the half cases of the main body case 11 to each other is tightened in a region in front of the sensor substrate 23. Therefore, it is not necessary to provide a screw hole or screw boss portion into which the screw 2 is tightened in a region on the rear side of the sensor substrate 23 of the main body case 11, and accordingly, the main body case 11, and thus the tool main body portion 10. It is possible to make the machine L compact.

  In addition, according to the present embodiment, the two power lines for the sensor substrate 23 are connected to the front surface of the projecting portion that projects to the outer peripheral side from the stator 21. For this reason, it is not necessary to secure a wiring space on the rear surface side of the sensor substrate 23, and the main body case 11 and thus the tool main body 10 can be made compact in the machine length L direction accordingly.

  Further, an air inlet 12b for sucking motor cooling air is provided on the rear surface and the left and right side surfaces of the rear case 12, and the space between the rear case 12 and the sensor board 23 is accompanied by the rotation of the cooling fan 28. This is the ventilation path for the motor cooling air generated. A sensor substrate 23 is arranged to face the rear case 12. For this reason, since the outside air immediately after being sucked in from the air inlet 12b is blown against the rear surface of the sensor substrate 23, the switching element 29 is efficiently cooled.

  Further, in the present embodiment, the central portion of the cooling fan 28 is bent, and the support portion for the motor shaft 24 is set on the inner peripheral side of the stator 21, whereby the cooling fan 28 is positioned at the position in the motor axial direction. It overlaps with the stator 21. In this respect as well, the DC brushless motor 20 and thus the tool main body 10 are made compact in the machine length L direction.

  Various modifications can be made to the embodiment described above. For example, the configuration in which the sensor substrate 23 is attached to the rear side of the stator 21 is illustrated, but conversely, the sensor substrate is attached to the front side of the stator, and the front bearing 25 is disposed in the inner peripheral hole thereof, so Can be made compact. In this case, the cooling fan can be disposed behind the rotor 22.

  Further, the main body case 11 whose back side is closed by the rear case 12 is illustrated. However, the rear side bearing is also illustrated in the case of the main body case in which a portion corresponding to the rear case is integrally formed. Can be arranged in the inner peripheral hole of the sensor substrate to achieve compactness in the machine length L direction.

  In the embodiment described above, an impact-type screw tightening machine (impact driver) has been exemplified as the electric tool. The present invention can be widely applied to other types of electric tools such as a grinding tool such as a DC brushless motor as a drive source.

1 ... Power tool 2 ... Screw (for split case connection)
DESCRIPTION OF SYMBOLS 3 ... Strap 4 ... Hook 5 ... Illuminating tool (LED), 5a ... Transparent cover 6 ... Changeover switch 7 ... Controller, 7a ... Capacitor 8 ... Elastomer resin layer 10 ... Tool body part L ... Tool body length 11 ... Body case 11a: Exhaust port J ... Split face mating surface 12 ... Rear case 12a ... Bearing holding part, 12b ... Intake port 13 ... Screw 15 ... Grip part 16 ... Switch lever 17 ... Battery mounting part 18 ... Main switch 19 ... Display 20: DC brushless motor 21 ... Stator 21b ... Electrical insulating member 22 ... Rotor, 22a ... Rotor core, 22b ... Magnet 23 ... Sensor substrate, 23a ... Set screw, 23b ... Inner peripheral hole 24 ... Motor shaft 25 ... Bearing (front side)
26 ... Bearing (rear side)
27 ... Intermediate partition wall 28 ... Cooling fan 29 ... Switching element 30 ... Planetary gear mechanism 31 ... Drive shaft 32 ... Rotary striking mechanism 32a ... Hammer, 32b ... Compression spring, 32c ... Steel ball 33 ... Anvil 34 ... Bearing 35 ... Chuck part 36 ... Output shaft 40 ... Battery pack

Claims (7)

DC brushless motor,
A body case for housing the DC brushless motor;
An output shaft provided at a front portion of the main body case and rotated by the DC brushless motor;
A rear case for closing the rear side of the main body case;
A power tool having a grip portion coupled to the main body case ,
The DC brushless motor detects a rotational position of the stator supported by the main body case, a rotor rotatably supported on the inner peripheral side of the stator via a motor shaft, and the rotor. has a magnetic sensor on the front, with a plurality of switching elements on the rear surface, and a sensor substrate fixed to the rear of the stator, and a fan disposed in front side of the stator,
Providing a front bearing and a rear bearing for supporting the motor shaft in the front-rear direction ;
The sensor board and the switching element are arranged so as to overlap the outer peripheral side of the rear bearing, and an air inlet is provided in the rear case so as to face a peripheral edge of the sensor board, and an exhaust is provided in the main body case. Electric tool with a mouth . The electric tool according to claim 1,
The rear case is fixed to the main body case by two screws on the left and right,
The plurality of switching elements are disposed above and below the two screws,
The power tool is disposed on the upper side and the lower side of the two screws. The electric tool according to claim 1,
An electric tool in which an elastomer resin layer is disposed above and below the intake port in the rear case. DC brushless motor,
A body case for housing the DC brushless motor;
An output shaft provided at a front portion of the main body case and rotated by the DC brushless motor;
A rear case for closing the rear side of the main body case;
A power tool having a grip portion coupled to the main body case ,
The DC brushless motor detects a rotational position of the stator supported by the main body case, a rotor rotatably supported on the inner peripheral side of the stator via a motor shaft, and the rotor. Including a sensor substrate disposed opposite to the end face of the stator,
In the peripheral part of the rear case, an air inlet for introducing outside air is provided to face the peripheral part of the sensor substrate,
A bearing for rotating and supporting the motor shaft is held by a bearing holding portion provided in the rear case, and the bearing holding portion enters an inner peripheral hole of the sensor substrate, and the bearing holding portion and the bearing A power tool in which a space portion in a radial direction with respect to an inner peripheral hole serves as a ventilation path for motor cooling air introduced from the intake port . The electric tool according to claim 4,
An electric tool comprising a cooling fan at a front portion of the rotor, wherein outside air is introduced from the intake port by rotation of the cooling fan. DC brushless motor,
A body case for housing the DC brushless motor;
An output shaft provided at a front portion of the main body case and rotated by the DC brushless motor;
A rear case for closing the rear side of the main body case;
A power tool having a grip portion coupled to the main body case ,
The DC brushless motor detects a rotational position of the stator supported by the main body case, a rotor rotatably supported on the inner peripheral side of the stator via a motor shaft, and the rotor. has a magnetic sensor on the front, with a plurality of switching elements on the rear surface, and a sensor substrate fixed to the rear of the stator, and a fan disposed in front side of the stator,
Providing a front bearing and a rear bearing for supporting the motor shaft in the front-rear direction ;
An electric tool in which the sensor substrate and the switching element are disposed so as to overlap with an outer peripheral side of the rear bearing, and intake ports are provided on the left and right sides of the rear surface of the rear case, and an exhaust port is provided in the main body case . The electric tool according to any one of claims 1 to 6, wherein an inner peripheral side of the sensor substrate is formed to have a larger diameter than an inner peripheral side of the stator.

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