JP5547827B2 - Electric tool with DC brushless motor - Google Patents

Description

This invention relates to an electric tool having a suitable DC brushless motor, for example as a drive source of a power tool such as an impact driver.

Conventionally, in this type of electric power tool, efforts have been made to make the device compact in order to improve the handling property (usability). For example, in order to make the tool body compact in the machine direction or to improve its maintainability, a tool using a DC brushless motor as a drive source is provided.
The DC brushless motor includes a rotor having a magnet (permanent magnet), a stator having a drive coil, a sensor substrate having a magnetic sensor for detecting the position of the magnetic pole of the rotor, and rotation detected by the sensor substrate. It is equipped with an electric circuit board that detects the position of the magnetic pole of the child and rotates the rotor by passing current to each drive coil of the stator based on this, and does not require a brush and commutator. Can be made compact and maintenance-free.

JP 2005-160196 A Japanese Patent No. 3601152

However, in an electric tool using a DC brushless motor as a drive source, it is necessary to further reduce the size of the tool body.
An object of the present invention is to further reduce the size of a DC brushless motor or an electric tool using this as a drive source in the length direction .

The above problems are solved by the present invention described below.
The present invention includes a main body case, a grip portion, a battery attachment portion, a brushless motor housed in the main body case and having a stator and a rotor, a first substrate portion attached to the battery attachment portion, and a rotor. a rotary shaft which is fixed, and a second substrate portion to be penetrated by the rotating shaft, Ru der power tool having a. In the present invention, the rotating shaft is rotatably supported by the first bearing and the second bearing. The first bearing is held by the main body case, and the second bearing is held by the intermediate partition wall. The second substrate portion includes an escape hole that penetrates the rotating shaft, a magnetic sensor mounting portion for mounting the magnetic sensor, a wiring connection portion that projects in the radial direction of the rotating shaft, and screw fixing for screwing the stator. Part. Moreover, the present invention has a configuration in which the first bearing is overlapped with the second substrate portion with respect to the axial position of the rotating shaft.

According to the above invention, it is possible to make the DC brushless motor and the power tool using this as a drive source compact in the length direction .

It is a longitudinal cross-sectional view of the impact screw fastening machine which uses the DC brushless motor which concerns on embodiment of this invention as a drive source. It is a longitudinal cross-sectional view of the DC brushless motor which concerns on embodiment of this invention. It is a rear view of DC brushless motor. This figure is the figure which looked at the DC brushless motor from the direction of arrow (3) in FIG. FIG. 3 is a cross-sectional view of the stator taken along line (4)-(4) in FIG. It is a rear view of a stator core alone. It is a longitudinal cross-sectional view of a rotor. It is the figure which looked at the rotor from the arrow (7) direction in FIG. It is the rear view which looked at the electric tool from the arrow (8) direction in FIG. FIG. 9 is a cross-sectional view taken along line (9)-(9) in FIG. 8 and is a cross-sectional view of the DC brushless motor. It is a figure which shows the attachment structure of another form about the attachment structure of a rear case. This figure has shown the state which looked at the tool main body from back. It is a figure which shows the attachment structure of another form about the attachment structure of a rear case. This figure is a cross sectional view taken along line (11)-(11) in FIG. 10, and is a transverse cross section of the rear part of the tool body. It is a longitudinal cross-sectional view of DC brushless motor provided with the holding structure of another form about the holding structure of a rear side bearing. FIG. 13 is a rear view of the DC brushless motor of FIG. 12. It is a longitudinal cross-sectional view of DC brushless motor provided with the holding structure of another form about the holding structure of a rear side bearing. FIG. 15 is a rear view of the DC brushless motor of FIG. 14. It is a longitudinal cross-sectional view of the impact screwing machine of the form with which the motor cooling fan was arrange | positioned at the rear part side of DC brushless motor. In the figure, the grip portion is not shown.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an electric tool 1 using a DC brushless motor M 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, the front-rear direction of the electric power tool 1 will be described with the right side being the front side and the left side being the rear side in FIG.
The electric tool 1 includes a tool body 10 and a grip portion 15 provided in a state of protruding from a side portion of the tool body 10. The tool body 10 includes a substantially cylindrical body case 11. The rear part of the main body case 11 is closed by a rear case 12.
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 base portion (upper portion in FIG. 1). ing. 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 M as a drive source.
A battery mounting portion 17 for mounting a battery pack P 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). A battery pack P is mounted on the lower surface side of the battery mounting portion 17.

In the main body case 11, a DC brushless motor M, a planetary gear mechanism 20, a spindle 21, a rotary striking mechanism 22, and an anvil 27 are accommodated coaxially in order from the rear side. The rotational output of the DC brushless motor M is transmitted to the anvil 27 via the reduction gear train 20 (a planetary gear mechanism in the case of the present embodiment) and the rotary impact mechanism 22.
The rotary striking mechanism 22 has a function of converting the rotation of the spindle 21 into a rotational striking motion with respect to the anvil 27. The hammer 23 is supported coaxially with the spindle 21 so as to be rotatable and axially movable, and the hammer. A compression spring 24 that biases the tip 23 toward the distal end side, and steel balls 25 and 25 that restrict the axial movement and rotation of the hammer 23 are provided.
The anvil 27 is coaxially supported at the tip of the spindle 21 so as to be relatively rotatable. The anvil 27 is supported through a cylindrical bearing 26 attached to the tip of the main body case 11 so as to be rotatable about its axis and not to be displaced in the axial direction.
At the stage where the screw tightening resistance is small after the start of the screw tightening, the anvil 27 rotates in the screw tightening direction integrally with the spindle 21 via the rotary impact mechanism 22. When the screw tightening proceeds and the screw tightening resistance is greater than the rotational force transmitted to the spindle 21, the hammer 23 moves back in the axial direction against the compression spring 24, and then rotates while moving forward with the compression spring 24. Stroke 27 in the screwing direction.
A chuck portion 28 for mounting a tip tool (not shown) such as a driver bit or a socket bit is provided at the tip portion of the anvil 27.

The DC brushless motor M as a drive source is a motor having a four-pole structure. As shown in FIG. 1, the DC brushless motor M is fixed to a rotor (rotor) 50 having a magnet (permanent magnet) and the inside of the main body case 11 to rotate. A stator (stator) 60 positioned around the child 50, a sensor board 70 for detecting the position of the magnetic pole of the rotor 50, and an electric control board 80 having a drive circuit are provided. FIG. 2 shows a single DC brushless motor M. However, the electric control board 80 is omitted. Details of the rotor 50 are shown in FIGS. The rotor 50 includes a rotor core 51 in which a large number of circular thin steel plates 51a to 51a are stacked. Around the rotor core 51, four magnets 52 to 52 are fixed in a state where N poles and S poles are alternately positioned in the circumferential direction. For this reason, as shown by a broken line in FIG. 7, a magnetic flux line B straddling between the magnets 52 adjacent to the circumferential direction is generated in the rotor core 51.
A through hole 51 b is formed at the center of the rotor core 51. The rotating shaft 53 is fixed to the through hole 51b. Balance correction holes 54 to 54 are respectively provided in parallel with each other along the rotation axis J of the rotation shaft 53 at the four equally-divided positions around the rotation shaft 53. These four balance correction holes 54 to 54 are all arranged along the same circumference in the case of this embodiment.
The four balance correction holes 54 to 54 are positions that are not affected by the magnetic flux lines B (positions that do not adversely affect the motor performance), and positions that are substantially in the center in the circumferential direction of each magnet 52 (the magnetic poles). (Center). Further, the four balance correction holes 54 to 54 are provided so as to penetrate between both end surfaces of the rotor core 51 with the same diameter.

The balance correction member 55 is press-fitted into all or part of the four balance correction holes 54 to 54. Regarding the weight of the balance correction member 55 to be press-fitted or to which balance correction hole 54 the balance correction member 55 is to be press-fitted, the deviation of the center of gravity of the rotor 50 from the rotation axis J ( It is set appropriately so that this unbalance is corrected. Further, the depth at which the balance correction member 55 is press-fitted (the position in the axis J direction in the balance correction hole 54) is also appropriately set so as to correct the unbalance in the rotation direction of the rotor 50. In the present embodiment, the balance correcting member 55 is a round bar (brass bar) having a constant diameter made of brass (brass).
The rotating shaft 53 protrudes from both sides of the rotor core 51. As shown in FIG. 1, the front side (reduction gear train 20 side) of the rotary shaft 53 is rotatably supported via a front bearing 56 and the rear side via a rear bearing 57. The front bearing 56 is held in a bearing holder 13 a provided on the rear surface of the intermediate partition wall 13 that divides the body case 11 in the front-rear direction. The inside of the main body case 11 is partitioned by the intermediate partition wall 13 into a DC brushless motor M side (rear side) and a rotary impact mechanism 22 side (front side).
A cooling fan 58 is fixed to the rotary shaft 53 between the front bearing 56 and the rotor core 51. The boss portion 58a of the cooling fan 58 is sandwiched from both sides by the bearing 56 and the rotor core 51, so that the position is fixed in the axial direction.
The rear bearing 57 is held in a bearing holding portion 12 a provided at the center of the rear case 12. A sleeve 59 is interposed on the rotary shaft 53 between the rear bearing 57 and the rear surface of the rotor core 51. By sandwiching the boss portion 58a of the cooling fan 58, the rotor core 51 of the rotor 50 and the sleeve 59 between the front and rear bearings 56 and 57, these cannot be displaced in the axial direction and are integrated with the rotary shaft 53 for rotation. ing.
As shown in FIGS. 8 and 9, the rear case 12 is fixed (screwed) to the rear portion of the main body case 11 with two screws 14 and 14. The two screws 14 and 14 are tightened into screw holes 11 a and 11 a provided on the rear surface of the main body case 11. The two screw holes 11 a and 11 a are provided in a boss portion 11 b provided in the rear portion of the main body case 11. The two boss portions 11b and 11b are provided in the circumferentially bisected position with respect to the rotation axis J of the DC brushless motor M and are provided around the outer periphery (outer peripheral side) of the stator 60. Both boss portions 11 b and 11 b are provided in a state of projecting to the inner peripheral side of the main body case 11.

Next, as shown in FIG. 2, the stator 60 includes a stator core 61 having a laminated steel plate structure in which a large number of thin steel plates are laminated, and an electrically insulating member called a so-called insulator that electrically insulates the stator core. 62. FIG. 5 shows the stator core 61 alone. The stator core 61 has a cylindrical portion 61a having a cylindrical shape and six tooth portions 61b to 61b that protrude radially inward from the inner peripheral side of the cylindrical portion 61a. The six tooth portions 61b to 61b are arranged around the rotor 50 at equal intervals.
Boss relief portions 61d and 61d having a concave shape in an arc shape are formed on the outer circumferential surface of the cylindrical portion 61a and at a position equally divided in the circumferential direction. Both boss relief parts 61d and 61d are provided at the same position as the tooth part 61b (base part of the tooth part 61b) in the circumferential direction as shown in the figure, and the strength of the stator core 61 is ensured. Both boss relief portions 61 d and 61 d are provided so as to penetrate between the front and rear end faces of the stator core 61.
The boss portions 11b and 11b of the main body case 11 enter the boss relief portions 61d and 61d. By providing boss relief portions 61d and 61d on the stator 60 side of the DC brushless motor M and allowing the boss portions 11b and 11b on the body case 11 side to enter (release) the boss relief portions 61d and 61d. The minute body case 11 can be configured to be compact in the radial direction.
As described above, by positioning the screw holes 11a and 11a for screwing the rear case 12 to the main body case 11 on the outer peripheral side of the stator 60, the main body case is formed to be long backward, The main body case 11 can be formed shorter than a configuration in which a screw hole is provided at the rear. Further, even when the boss portion 11a for providing the screw hole 11a is provided, the boss relief portion 61d is provided on the outer peripheral surface of the stator 60 to allow the boss portion 11a to enter, so that the outer peripheral side of the main body case 11 In addition, the bosses 11a, 11a can be prevented from projecting large and having a large diameter (reducing the diameter of the main body case 11), and further reducing the length of the machine.

Although not shown, the boss escape portion 61d is not limited to two locations, but may be configured to have, for example, six locations at six equal positions in the circumferential direction. According to this, the freedom degree of the assembly position of the stator core around the rotation axis J can be increased with respect to the two boss portions 11b, 11b on the main body case 11 side.
The stator core 61 is covered with an electrical insulating member 62 in a range excluding the outer peripheral surface of the cylindrical portion 61a and the tip surface 61c of each tooth portion 61b. The tip surface 61 c of each tooth portion 61 b that is not covered by the electrical insulating member 62 is positioned with a certain gap between the tip surface 61 c and the peripheral surface of the rotor 50.
A drive coil 63 is wound around a portion of each tooth portion 61 b covered with the electrical insulating member 62.
A sensor substrate 70 is attached to the rear surface of the electrical insulating member 62. On the rear surface side of the electrical insulating member 62, a substantially circular step portion 62b is provided over the entire circumference. The sensor substrate 70 is mounted in the stepped portion 62b.
The sensor substrate 70 has a generally circular shape, and an escape hole 70a having a diameter through which the bearing holding portion 12a can be inserted is provided at the center thereof. The rear bearing 57 is located in the escape hole 70a. By positioning the rear bearing 57 in the escape hole 70a of the sensor substrate 70, the rear bearing 57 is positioned on the inner peripheral side of the electrical insulating member 62 and is held in a state that does not protrude from the rear end surface of the stator 60. Has been. That is, the height dimension of the bearing holding portion 12a of the rear cover 12 (the dimension projecting to the body case 12 side) is the rear of the electric insulating member 62 so that the rear bearing 57 is positioned on the inner peripheral side of the electric insulating member 62. It is set appropriately for the position of the end face.
By arranging the rear bearing 57 on the inner peripheral side of the electrical insulating member 62, the size of the DC brushless motor M in the machine length direction (left and right direction in FIGS. 1 and 2) is compact. As a result of shortening the DC brushless motor M as a drive source in the machine length direction, the machine length of the tool body 10 of the electric power tool 1 can be made compact, thereby improving the operability of the electric power tool 1.

As shown in FIG. 3, a terminal board portion 70b for wiring connection is provided in a state of projecting in the radial direction below the sensor substrate 70. The terminal plate portion 70b projects to the outer peripheral side (downward in FIG. 3) of the electrical insulating member 62 through a cutout portion 62c in which a part of the stepped portion 62b is cut out.
The three magnetic sensors 71 to 71 attached to the sensor substrate 70 are sensors for detecting which position of the magnetic pole of the rotor 50 is opposed to which tooth portion 61b of the stator 60. In, Hall elements are used. The sensor substrate 70 is screwed to the rear surface of the electrical insulating member 62 with three screws 72 to 72, whereby the three magnetic sensors 71 to 71 are connected to the three tooth portions 61 b to 61 b adjacent in the circumferential direction. Are arranged in phase with each other. While the three magnetic sensors 71 to 71 detect the positions of the magnetic poles of the rotor 50, the rotor 50 is rotated by passing current from the electric control board 80 to the drive coils 63 to 63 in order. The functions of the sensor board 70 and the electric control board 80 are basic configurations of a general DC brushless motor, and no particular change is required in the present embodiment.
The three screw holes 62a to 62a for tightening the three screws 72 to 72 are located at the three-way positions in the circumferential direction as shown in FIG. 4, and are located between the adjacent tooth portions 61b and 61b of the stator core 61. Has been placed. Since each screw hole 62a is positioned between the adjacent tooth portions 61b, 61b, the cylindrical boss portion having the screw hole 62a does not get in the way, and the winding of a sufficient length over the entire length of the tooth portion 61b. Lines can be applied, thereby providing a compact and efficient drive coil 63.
The electric control board 80 having the drive circuit is attached along the lower surface side of the battery attachment portion 17 for attaching the battery pack P. On the upper surface side of the electric control board 80, a power supply smoothing capacitor 81, a power supply line 82, power lines 83 to 83, and the like are coupled so as to rise upward. It is arranged using the space.

According to the DC brushless motor M configured as described above, of the bearings 56 and 57 that support the rotating shaft 53 of the rotor 50, the bearing 57 on the sensor substrate 70 side that is attached along the rear surface of the stator 60. The sensor board 70 is disposed in an escape hole 70a so that the position in the rotation axis J direction (position in the machine length direction) does not protrude from the inner peripheral side of the electrical insulation member 62 and hence from the rear end of the electrical insulation member 62. The bearing 57 is arranged at the position.
For this reason, the DC brushless motor M can be made compact in the machine length direction (rotation axis J direction) as compared with the conventional configuration in which the bearings are arranged at positions away from the end face of the stator. By using a DC brushless motor M compacted in the machine length direction as a drive source, the electric tool 1 can be made compact in the machine length direction.
Further, in the case of this embodiment, a bearing holding portion 12a is provided at substantially the center of the inner surface of the rear case 12 that closes the rear portion of the body cover 11, and the rear bearing 57 is held by the bearing holding portion 12a. Since the structure is positioned on the inner peripheral side of the electrical insulating member 62, the bearing 57 can be held at a predetermined position by a simple structure using the rear case 12, and this also increases the length of the electric tool 1. It can be configured compactly.

Various modifications can be made to the embodiment described above. For example, although the configuration in which the rear case 12 is screwed to the main body case 11 is illustrated, the rear case 31 is not the main body case 30 but the electric insulating member 33 of the DC brushless motor M as shown in FIGS. but it may also be configured to be screwed. About the point similar to above-described embodiment, the description is abbreviate | omitted using a same code | symbol. In the case of this embodiment, the rear case 31 is fixed to the electric insulating member 33 of the DC brushless motor M by two screws 32, 32. On the rear surface of the electrical insulating member 33, a screwing pedestal portion 33a is provided in an annular shape along a circumference centered on the rotation axis J. Two screw holes 33b and 33b are provided in the circumferentially bisected position of the screw base 33a. The rear case 31 is fixed to the rear surface of the electrical insulating member 33 by tightening the screws 32 into the two screw holes 33b and 33b.
A bearing holding portion 31 a is provided at the center of the inner surface of the rear case 31. A rear bearing 57 is held in the bearing holding portion 31a. As a result, the rear bearing 57 is positioned on the inner peripheral side of the electrical insulating member 62.
On the outer surface of the rear case 31, there are provided recesses 31b, 31b for accommodating the heads of the tightened screws 32, 32. For this reason, in the state which tightened both screws 32 and 32, those heads are in the state where they do not protrude from the outer surface of the rear case 31, thereby improving the appearance of the electric power tool 1 and the screws 32. The operability of the electric power tool 1 can be improved in that it is prevented from being caught on other parts of the heads.
According to the mounting structure of the rear case 31 configured as described above, the tool body 10 can be configured to be more compact in the radial direction than the configuration in which the rear case 12 is screwed to the body case 11. it can.

In the above description, the configuration in which the rear bearing 57 that supports the rotating shaft 53 is held in the rear case 12 (31) is illustrated. However, for example, as shown in FIGS. 12 and 13, separately from the rear case 12 (31). Ru can also be positioned on the inner peripheral side of the electrically insulating member 62 the rear bearing 57 with the bearing holding member 35.
In the case of this embodiment, the bearing holding member 35 includes a bearing holding portion 35a having a substantially cylindrical shape with a bottom. A rear bearing 57 is held inside the bearing holding portion 35a.
The mounting edge portions 35b to 35b are respectively provided in a state of projecting outward in the radial direction at the three equal positions around the bearing holding portion 35a. On the other hand, on the rear surface of the electrical insulating member 36, a pedestal portion 36a capable of contacting each of the mounting edge portions 35b is provided in a state of projecting to the inner peripheral side.
By attaching the three attachment edge portions 35b to 35b to the pedestal portion 36a of the electrical insulating member 36, and screwing the attachment edge portions 35b to the pedestal portion 36a with screws 37 in this contact state. The bearing holding member 35 is attached to the rear portion of the electrical insulating member 36.
In the case of this configuration as shown in FIG. 12, since the bearing 57 is located closer to the rotor 50 than the sensor substrate 70 and is located on the inner peripheral side of the stator 60, the sleeve 38 is more than the sleeve 59. Accordingly, the length of the DC brushless motor M is further shortened.
Also with this configuration, the rear bearing 57 can be positioned on the inner peripheral side of the electric insulating member 62 (the inner peripheral side of the stator 60), thereby shortening the length of the DC brushless motor M and reducing the electric tool 1 It can be configured compactly.

Further modifications can be made to the above embodiment. For example, the bearing holding member 40 used in the bearing holding structure shown in FIGS. 14 and 15 includes a bearing holding portion 40a that holds the rear bearing 57, and three pieces that protrude outward in the radial direction from the surrounding three-part positions. Mounting edge portions 40b to 40b are provided. The three attachment edge portions 40b to 40b are formed longer than the attachment edge portion 35b. On the other hand, as described above, the sensor substrate 70 is attached to the electrical insulating member 62 by the three screws 72 to 72 while being accommodated in the stepped portion 62 b provided on the rear surface of the electrical insulating member 62.
The three attachment edges 40b to 40b of the bearing holding member 40 are fastened together with the sensor substrate 70 to the electrical insulating member 62 by the screws 72 to 72. The three mounting edges 40b to 40b are fastened together with the sensor substrate 70 to the electrical insulating member 62, so that the bearing holding member 40 is attached along the rear surface of the electrical insulating member 62. The bearing 57 is held in the escape hole 70a of the sensor substrate 70 or at a position closer to the rotor core 51 than this position (right side in FIG. 14) and on the inner peripheral side of the electric insulating member 62 and thus on the inner peripheral side of the stator 60. Has been.
In particular, also in this configuration, the rear bearing 57 can be brought closer to the position closer to the rotor 50 by forming the bearing holding portion 40a long in the axis J direction. For this reason, the sleeve 49 is shorter than the sleeve 59.
Even with the DC brushless motor M provided with this bearing holding structure, the size of the machine length direction can be further shortened to make the electric tool 1 compact. Further, since it is fastened Configurations in the sensor substrate 70 and the bearing holding member 40 screws 72-72 to an electrical insulating member 62, Ru can be simplified of the DC brushless motor M of the assembly process.

Each embodiment described above can be further modified. In the embodiment described above, of the front and rear bearings 56 and 57 that support the rotating shaft 53, the rear bearing 57 is positioned on the inner peripheral side of the electrical insulating member 62 (the inner peripheral side of the stator 60). However, for example, as shown in FIG. 16, the bearing 56 on the front side (reduction gear train 20 side) is positioned on the inner peripheral side of the electrical insulating member 62, so that the length of the DC brushless motor M and thus the length of the electric tool 1 is made compact. be able to.
In the case of this configuration, as shown in the figure, the cooling fan 48 for cooling the motor is supported on the rear side of the rotating shaft 53, and the sensor substrate 45 is attached on the front side of the electrical insulating member 62.
In the case of this bearing holding structure, a stepped portion 62d for housing the sensor substrate 45 is provided on the front side (right side in FIG. 16) of the electrical insulating member 62. The sensor substrate 45 itself is the same as the sensor substrate 70, and an escape hole 45a is provided at the center thereof.
Also, a bottomed cylindrical bearing holding portion 13b is provided on the rear surface side of the intermediate partition wall 13 that partitions the main body case 11 forward and backward. The bearing holding portion 13b protrudes to the rear side with a larger dimension than the bearing holding portion 13a. A front bearing 56 is held on the front end side (rear end side) of the bearing holding portion 13a. As shown in the figure, the front bearing 56 is located in the escape hole 45a of the sensor substrate 45 or closer to the rotor core 51 than the front hole 56a and on the inner peripheral side of the electric insulating member 62 (inner peripheral side of the stator 60). positioned.
On the other hand, the rear bearing 57 is held in the bearing holding part 12 a of the rear case 12. A cooling fan 48 is supported on the rotating shaft 53 between the rear bearing 57 and the rotor 50.
Also with the DC brushless motor M configured as described above, the front bearing 56 that supports the rotating shaft 53 of the rotor 50 is positioned on the inner peripheral side of the electric insulating member 62 (the inner peripheral side of the stator 60) in the rotational axis J direction. ). For this reason, the DC brushless motor M can be made compact in the machine length direction, thereby making the machine length of the electric power tool 1 compact and improving its operability.
In the embodiment described above, the DC brushless motor M used as the drive source of the electric tool 1 is exemplified, but the present invention can be grasped as an invention of the DC brushless motor itself. In a DC brushless motor, one or both of the front and rear bearings that support the rotating shaft of the rotor are arranged on the inner peripheral side of the electrical insulating member of the stator, so that the DC brushless motor itself is more compact in the length direction than before. Can be

M ... DC brushless motor 1 ... Electric tool (impact screw tightening machine)
DESCRIPTION OF SYMBOLS 10 ... Tool main body 11 ... Main body case, 11a ... Screw hole, 11b ... Boss part 12 ... Rear part, 12a ... Bearing holding part 13 ... Middle partition wall, 13a, 13b ... Bearing holding part 15 ... Grip part 21 ... Spindle 22 ... Rotating striking mechanism 27 ... anvil 30 ... main body case 31 ... rear case, 31a ... bearing holding portion, 31b ... concave portion 32 ... screw 33 ... electric insulation member (insulator), 33a ... screw fixing base portion 35 ... bearing holding member, 35a ... Bearing holding part, 35b ... Mounting edge 36 ... Electrical insulating member (insulator), 36a ... Base 40 ... Bearing holding member, 40a ... Bearing holding part, 40b ... Mounting edge 45 ... Sensor substrate, 45a ... Relief hole 48 ... Motor cooling fan 50 ... Rotor
DESCRIPTION OF SYMBOLS 51 ... Rotor core 53 ... Rotating shaft J ... Rotating axis 56 ... Front side bearing 57 ... Rear side bearing 58 ... Cooling fan 60 ... Stator (stator)
61 ... Stator core 61a ... Cylindrical part, 61b ... Tooth part, 61d ... Boss relief part 62 ... Electrical insulation member (insulator)
62a ... Screw hole, 62b ... Stepped portion (rear side), 62d ... Stepped portion (front side)
63 ... Driving coil 70 ... Sensor substrate, 70a ... Relief hole 71 ... Magnetic sensor (Hall element)
80 ... Electric control board

Claims (1)

A main body case, a grip section, a battery mounting section, a brushless motor housed in the main body case and having a stator and a rotor, a first board section mounted on the battery mounting section, and fixed to the rotor. An electric tool having a rotating shaft and a second substrate portion that is penetrated by the rotating shaft and held by the stator ,
The rotating shaft is rotatably supported by a first bearing and a second bearing, the first bearing is held by the body case, and the second bearing is supported by an intermediate partition wall. Is retained,
The second substrate unit includes a sensor substrate, a screw for holding the sensor substrate on the stator, and a magnetic sensor attached to the sensor substrate.
An electric tool characterized in that the first bearing is overlapped with the second substrate portion with respect to the axial position of the rotating shaft .

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