JP2018111206A - Screw tightening electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain suitable durability and achieve compactification.SOLUTION: A screw driver 1 includes: a brushless motor 22; a front housing 4 for housing the brushless motor 22; a spindle 54 rotated by driving of the brushless motor 22; a rear housing 5 which is connected to the rear of the front housing 4 in a loop form, and has a grip portion 7 formed on the rear end; a trigger switch 8 arranged on the grip portion 7; an installation part 11 that is formed on the lower part of the grip portion 7 and to or from which a battery pack 12 is attachable and detachable; and a control circuit board 19 arranged on the installation part 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a screw tightening electric tool used for screw tightening work.

  As disclosed in Patent Document 1, a screw tightening electric tool has, at a front end portion of a housing that houses a motor, a first spindle that is rotationally driven by the motor, and a second spindle that can hold the tip tool, When the second spindle moves backward, a rotation drive unit is provided that enables screw tightening by transmitting the rotation of the first spindle to the second spindle.

JP 2010-46739 A

  In the above conventional screw tightening electric tool, a commutator motor is used as a motor. However, there is a problem of durability due to wear of the brush, and there is a possibility that it becomes an obstacle to downsizing.

  Accordingly, an object of the present invention is to provide a screw-tightening electric tool that can achieve suitable durability and can be made compact.

In order to achieve the above object, the invention according to claim 1 is connected in a loop to the brushless motor, the front housing that houses the brushless motor, the spindle that rotates by driving the brushless motor, and the rear of the front housing, A rear housing that forms a grip portion at the rear end, a trigger switch that is disposed in the grip portion, a mounting portion that is formed in the lower portion of the grip portion and to which the battery pack can be attached and detached, and a control circuit board that is disposed in the mounting portion It is characterized by comprising.
According to a second aspect of the present invention, in the configuration of the first aspect, the brushless motor is provided with a sensor circuit board, and the trigger switch and the sensor circuit board are electrically connected to the control circuit board via cords, respectively. It is characterized by.
According to a third aspect of the present invention, in the configuration of the first or second aspect, the control circuit board is arranged in a posture extending in the front-rear direction.
According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects, the front housing and the rear housing are formed by assembling the left and right half housings with screws, and the mounting portion has a side view region of the rear housing. A screwing position is provided in front of the control circuit board.

  According to the present invention, the adoption of the brushless motor increases the power transmission efficiency and can be expected to be compact, and can be screwed with low power. In addition, durability is improved because no brush is used.

It is an external view of the screw driver of form 1. It is a longitudinal cross-sectional view of the screw driver of form 1. It is explanatory drawing of a sensor circuit board. It is explanatory drawing of the example of a change of a control circuit board. It is a longitudinal cross-sectional view of the screw driver of form 2. It is an external view of the screw driver of form 3. It is a longitudinal cross-sectional view of the screw driver of form 3. It is a longitudinal cross-sectional view of the screw driver of form 4. It is a longitudinal cross-sectional view of the screw driver of form 5. It is explanatory drawing of an operation panel. It is a longitudinal cross-sectional view of the screw driver of form 6.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Form 1]
FIG. 1 is an external view of a screw driver 1 which is an example of a screw tightening electric tool, and FIG. 2 is a longitudinal sectional view thereof. The housing 2 of the screw driver 1 is formed by assembling left and right half housings 2a, 2b with screws 3, 3,..., And a front housing (on the right side of FIGS. 4) and a rear housing 5 connected in a loop shape behind the front housing 4 is formed. Reference numeral 6 denotes a hook provided on the rear surface of the front housing 4. The rear housing 5 has a vertical grip portion 7 formed at the rear end, and a trigger switch 8 having a trigger 9 protruding forward is accommodated in the grip portion 7. A forward / reverse switching button 10 is provided above the trigger switch 8.

In addition, a battery pack 12 serving as a power source is detachably mounted on a mounting portion 11 formed below the grip portion 7. The battery pack 12 has a pair of left and right slide rails 14 on the upper surface of a case 13 that houses a plurality of storage batteries, and a pair of guide rails (not shown) provided on the mounting portion 11. It can be attached to the attachment portion 11 by being fitted from the front and sliding backward. In this mounted state, the terminal plate 16 of the terminal block 15 provided in the mounting portion 11 enters the case 13 and is electrically connected to a terminal (not shown) in the case 13. Reference numeral 17 denotes a locking hook that is provided in the case 13 so as to protrude upward and biased, and is locked to a recess 18 provided in the mounting portion 11 in the mounted state to prevent the battery pack 12 from coming off.
Further, on the upper side of the terminal block 15, there is provided a control circuit board 19 on which a capacitor 20 and a microcomputer are mounted and molded with resin. The control circuit board 19 and the trigger switch 8 are electrically connected by cords 21, 21,.

  The brushless motor 22 is an inner rotor type having a stator 23 and a rotor 24 and is disposed below the front housing 4. First, the stator 23 is wound around the stator core 25 via the stator core 25, the front insulating member 26 and the rear insulating member 27 provided before and after the stator core 25, and the front insulating member 26 and the rear insulating member 27. A plurality of coils 28, 28,. In addition, the rotor 24 is arranged on the outer side of the rotating shaft 29 positioned around the shaft, the cylindrical rotor core 30 disposed around the rotating shaft 29, and the rotor core 30. The permanent magnets 31, 31... With alternating polarities, and a plurality of sensor permanent magnets 32, 32. At the front end of the front insulating member 26, as shown in FIG. 3, three rotation detection elements 34, 34,... That detect the position of the sensor permanent magnet 32 of the rotor 24 and output a rotation detection signal, and a coil 28 A sensor circuit board 33 on which six switching elements 35, 35,... 36 is a screw for mounting the sensor circuit board 33, 37 is a protrusion protruding from the front end surface of the front insulating member 26 and fitting into a small hole of the sensor circuit board 33, 38 is a coil connecting portion, and 39 is protruding downward. The tongue piece 39 includes a plurality of cords 40, 40... (A power line 40 a for sending power from the control circuit board 19, and a control And a signal line 40b for transmitting a signal from the circuit board 19).

Further, the stator 23 is held in an accommodation chamber 42 formed by a rib 41 erected on the inner surface of the front housing 4 with the axis line oriented in the front-rear direction. Is supported rotatably by a bearing 43 held by the rib 41 on the front side and a bearing 44 held by the rib 41 on the rear side of the storage chamber 42. A centrifugal fan 45 for cooling the motor is fixed in front of the bearing 44 in the rotating shaft 29, and a plurality of air inlets 46, 46,... Are formed in a radially outer portion of the sensor circuit board 33 in the front housing 4. A plurality of exhaust ports 47, 47... Are formed in the radially outer portion of the centrifugal fan 45.
The rear end of the rotating shaft 29 protrudes rearward from the accommodation chamber 42, and the first gear 48 is fixed thereto. Above the rotating shaft 29, a gear shaft 49 is supported in parallel with the rotating shaft 29 by front and rear bearings 50, 50, and a second gear 51 provided at the rear end of the gear shaft 49 meshes with the first gear 48. doing. A third gear 52 having a smaller diameter than the second gear 51 is formed at the front end of the gear shaft 49.

  An output unit 53 is disposed above the brushless motor 22. The output portion 53 is provided across a first spindle 54 that is pivotally supported on the front housing 4 via a bearing 55 and a cylindrical tip housing 56 that is connected to the front of the front housing 4 from the front housing 4. And a second spindle 57 as a tip tool holding portion that is pivotally supported via a bearing 58. The first spindle 54 has a fourth gear 59 integrally fixed to the rear portion thereof, and the fourth gear 59 is engaged with the third gear 52 of the gear shaft 49. A cam 60 is integrally coupled to the front of the fourth gear 59 via a ball 61 in the rotational direction.

On the other hand, the second spindle 57 is coaxially arranged so as to be movable forward and backward in front of the first spindle 54, and a mounting hole 62 into which a driver bit as a tip tool can be inserted and mounted is formed at the front end, and at the rear end, A cam portion 63 facing the cam 60 is formed. The cam portion 63 meshes with the cam 60 in the forward rotation direction, and a coil spring 64 is interposed between the cam 60 and the cam portion 63. That is, between the first spindle 54 and the second spindle 57, there is formed a clutch (cam 60, cam portion 63) through which the rotation of the first spindle 54 is transmitted when the second spindle 57 is retracted.
The tip of the first spindle 54 is inserted into a bottomed hole 65 formed in the rear part of the second spindle 57, and a one-way clutch 66 that engages in the reverse rotation direction is provided between the spindles 54 and 57. ing. Reference numeral 67 denotes a depth adjustment cap that is fitted to the front end of the tip housing 56 so that the front-rear position can be changed.
Further, a cap-shaped lid housing 68 is fixed to the front of the brushless motor 22 at the lower part of the front end of the front housing 4, and an LED 69 as a light is housed in a posture facing obliquely forward under the lid housing 68. The control circuit board 19 is electrically connected via the cord 70.

  In the screw driver 1 configured as described above, when the driver bit mounted on the second spindle 57 is pressed against the screw to be tightened and the second spindle 57 is moved backward, the cam portion 63 is connected to the cam 60 of the first spindle 54. Engage. When the trigger 9 is pushed in and the trigger switch 8 is turned on in this state, power is supplied from the battery pack 12 and the brushless motor 22 is driven. That is, the microcomputer of the control circuit board 19 obtains the rotation detection signal indicating the position of the sensor permanent magnet 32 of the rotor 24 output from the rotation detection element 34 of the sensor circuit board 33, and acquires the rotation state of the rotor 24. According to the acquired rotation state, the ON / OFF of each switching element 35 is controlled, and the rotor 24 is rotated by causing a current to flow sequentially to each coil 28 of the stator 23. However, the operation amount (push-in amount) of the trigger 9 is transmitted as a signal to the microcomputer, and the rotation of the rotor 24 is controlled according to the operation amount. Note that it is also possible to use the trigger 9 by pushing the trigger 9 first to move the second spindle 57 backward while the brushless motor 22 is rotated.

When the rotor 24 rotates in this manner, the rotating shaft 29 and the first gear 48 rotate to reduce and rotate the gear shaft 49 via the second gear 51, and further to the first via the third gear 52 and the fourth gear 59. One spindle 54 is decelerated and rotated. Therefore, the second spindle 57 that engages with the cam 60 rotates and can be screwed with a driver bit. When the screw tightening advances and the second spindle 57 moves forward and the cam portion 63 is detached from the cam 60, the rotation of the second spindle 57 stops and the screw tightening ends.
On the other hand, to loosen the screw, when the forward / reverse switching button 10 is switched to the reverse rotation side, the rotor 24 rotates reversely and the first spindle 54 rotates reversely under the control of the microcomputer. Since the one-way clutch 66 is provided between the first spindle 54 and the second spindle 57, the second spindle 57 also rotates in the reverse direction, and the screw can be loosened by the driver bit.

When the centrifugal fan 45 rotates with the rotary shaft 29, the air sucked into the accommodation chamber 42 from the intake port 46 passes between the sensor circuit board 33 and the stator 23 and the rotor 24 and is discharged from the exhaust port 47. The Thereby, the sensor circuit board 33 and the brushless motor 22 are cooled.
In addition, when the trigger switch 8 is turned on, power is supplied from the control circuit board 19 and the LED 69 is turned on. Therefore, workability can be maintained even in a dark place where the front of the driver bit is irradiated.
Furthermore, since the brushless motor 22 and the LED 69 are close to each other, wiring is easy.

Thus, according to the screw driver 1 of the said form 1, by employ | adopting the brushless motor 22, motive power transmission efficiency becomes high and it can anticipate reduction in size, and screw fastening is attained with low electric power. In addition, durability is improved because no brush is used.
Furthermore, since the brushless motor 22 is disposed below the clutch, the back battery pack 12 is balanced and the feeling of use is excellent.
In addition, since the sensor circuit board 33 is not sandwiched between the first gear 48 and the like and the brushless motor 22, durability against heat and vibration becomes higher.
And since the tongue piece part 39 of the sensor circuit board 33 is formed downward, the wiring from the control circuit board 19 to the tongue piece part 39 becomes efficient.

In the first embodiment, the switching element 35 is provided on the sensor circuit board 33. However, it can be provided on the control circuit board 19 as shown in FIG. In FIG. 4, 71 is a microcomputer.
Further, the speed reduction mechanism from the rotary shaft to the first spindle can be appropriately changed by increasing the gear shaft or conversely omitting the gear shaft.

  Next, another embodiment of the present invention will be described. However, the same components as those in the first embodiment are denoted by the same reference numerals and redundant description is omitted.

[Form 2]
In the screw driver 1 </ b> A shown in FIG. 5, the direction of the brushless motor 22 is reversed, the sensor circuit board 33 is located on the rear side of the stator 23, and the centrifugal fan 45 is located on the front side of the stator 23. The point is different from Form 1. Therefore, here, the intake port 46 is disposed on the rear side of the housing 2 and the exhaust port 47 is disposed on the front side.
Further, a partition wall 42a for separating the cord 70 for the LED 69 and the outer periphery of the centrifugal fan 45 is formed so that the wind of the centrifugal fan 45 can be sent more efficiently.

As described above, also in the screw driver 1A of the above-described form 2, the adoption of the brushless motor 22 increases the power transmission efficiency and can be expected to be compact, and can be screwed with low power. Further, since the brush is not used, the same effect as in the first mode can be obtained, such as improvement in durability.
In particular, since the sensor circuit board 33 is closer to the control circuit board 19 than the first embodiment, there is an advantage that the wiring can be shortened.

[Form 3]
6 and 7, the housing 2 includes a motor housing 72 that houses the brushless motor 22 and the output portion 53 and extends in the front-rear direction, and a grip housing that extends downward from the rear end of the motor housing 72. 73, and a mounting portion 11 of the battery pack 12 is formed at the lower end of the grip housing 73. The LED 69 is housed obliquely upward in the mounting portion 11 above the terminal block 15.
Further, the control circuit board 19 here is integrally provided below the trigger switch 8 to form a switch assembly 74, and the control circuit board 19 and the sensor circuit board 33 of the switch assembly 74 are provided with cords 84, 84,. The control circuit board 19 and the LED 69 are electrically connected via the cords 85 and 85. In addition to the microcomputer 71 and the capacitor 20, an IPM (Intelligent Power Module) 75 is mounted on the control circuit board 19. This IPM contains a switching element (IGBT) and encloses a driver for driving the switching element.

Further, in the brushless motor 22, a connecting piece 76 that protrudes radially outward is provided on the rear insulating member 27 of the stator 23, and a cord 77 that supplies power to the coil 28 passes through the connecting piece 76 to the coil 28. It is connected.
A pinion 78 is fixed to the front end of the rotating shaft 29, and the pinion 78 directly meshes with a gear 79 integrated with the first spindle 54.

As described above, also in the screw driver 1B of the above-described aspect 3, by adopting the brushless motor 22, the power transmission efficiency is increased, so that compactness can be expected, and screwing can be performed with low power. Further, since the brush is not used, the same effect as in the first mode can be obtained, such as improvement in durability.
In particular, here, the adoption of the switch assembly 74 has the advantage that the labor of assembly is reduced and the wiring is concentrated in one place and the wiring work is facilitated.
Furthermore, since the centrifugal fan 45 is between the brushless motor 22 and the gear 79, the gear 79 can be directly or indirectly cooled in addition to the cooling of the brushless motor 22.
The position information of the rotor 24 is output from the sensor circuit board 33 through the signal line 40b. However, since the sensor circuit board 33 is on the rear side, the connection with the control circuit board 19 is facilitated. Further, since the connecting piece 76 of the rear insulating member 27 is also on the rear side, the connection with the control circuit board 19 is facilitated.

[Form 4]
In the screw driver 1 </ b> C shown in FIG. 8, the direction of the brushless motor 22 is reverse to that in the third mode, the sensor circuit board 33 is the front side, and the centrifugal fan 45 is the rear side.
Therefore, also in the screw driver 1 </ b> C of the above-described form 4, by adopting the brushless motor 22, the power transmission efficiency can be increased and compactness can be expected, and screw tightening can be performed with low power. Moreover, since the brush is not used, the same effect as that of the third aspect can be obtained, for example, the durability can be improved.

[Form 5]
In the screw driver 1D shown in FIG. 9, the control circuit board 19 is not the trigger switch 8, but is provided above the terminal block 15 in the same manner as in the first embodiment, and the power supply to the coil 28 is not an insulating member but a sensor circuit board 33. Is done through.
Further, here, an operation panel 80 shown in FIG. 10 is provided on the upper surface of the mounting portion 11 and behind the LED 69. The operation panel 80 is provided with a light switch 81, a remaining capacity display switch 82, and a battery indicator 83, and is electrically connected to the control circuit board 19. Each time the light switch 81 is pushed, the LED 69 is turned on. When the remaining illuminance changes stepwise and the remaining capacity display switch 82 is pushed, the battery indicator 83 lights a number of scales corresponding to the remaining capacity of the storage battery of the battery pack 12.

As described above, also in the screw driver 1D of the fifth aspect, the adoption of the brushless motor 22 increases the power transmission efficiency and can be expected to be compact, and can be screwed with low power. Further, since the brush is not used, the same effect as in the first mode can be obtained, such as improvement in durability.
In particular, the irradiation mode of the LED 69 can be changed by the light switch 81, and the remaining capacity of the battery can be known at a glance by the remaining capacity display switch 82, which is excellent in usability.

[Form 6]
In the screw driver 1E shown in FIG. 11, the direction of the brushless motor 22 is reversed from that of the fifth embodiment, the sensor circuit board 33 is the rear side, and the centrifugal fan 45 is the front side.
Therefore, also in the screw driver 1E of the above-described form 6, by adopting the brushless motor 22, the power transmission efficiency is increased, so that compactness can be expected, and screw tightening can be performed with low power. Moreover, since the brush is not used, the same effect as in the fifth aspect can be obtained, such as improvement in durability.
Furthermore, since the sensor circuit board 33 is on the rear side, there is an advantage that the wiring is shorter than in the fifth embodiment.

In common with modes 3 to 6, deceleration from the rotation shaft to the first spindle is performed by the pinion and the gear. However, the rotation shaft and the first spindle are arranged coaxially and reduced by the planetary gear mechanism. Can also be planned.
The switch assembly of form 3 and the operation panel of form 5 can also be used for the screw drivers of forms 1 and 2.

  1, 1A to 1E ··· Screwdriver 2 · · · Housing 4 · · · Front housing 5 · · Rear housing 8 · Trigger switch 11 · · Mounting portion 12 · · · Battery pack 15 · · · Terminal block 19, control circuit board, 22. brushless motor, 23, stator, 24, rotor, 25, stator core, 26, front insulation member, 27, rear insulation member, 28, coil 29 .. Rotating shaft, 30 .. Rotor core, 31 .. Permanent magnet, 32 .. Permanent magnet for sensor, 33 .. Sensor circuit board, 34 .. Rotation detecting element, 35 .. Switching element, 42. Storage chamber, 45 ... Centrifugal fan, 49 ... Gear shaft, 53 ... Output part, 54 ... First spindle, 57 ... Second spindle, 60 ... Cam, 63 ... Cam part, 71 ... Microcomputer , 74 ... Pitch assembly 80 .. control panel, 81 ... light switch, 82 ... residual capacity display switch.

Claims (4)

A brushless motor,
A front housing that houses the brushless motor;
A spindle that rotates by driving the brushless motor;
A rear housing connected in a loop to the rear of the front housing and forming a grip portion at the rear end;
A trigger switch disposed in the grip portion;
A mounting portion formed at a lower portion of the grip portion, to which the battery pack is detachable;
A screw tightening electric tool comprising: a control circuit board disposed in the mounting portion. The brushless motor is provided with a sensor circuit board,
The screw tightening electric tool according to claim 1, wherein the trigger switch and the sensor circuit board are electrically connected to the control circuit board via a cord, respectively.   The screw tightening electric tool according to claim 1, wherein the control circuit board is arranged in a posture extending in a front-rear direction.   The front housing and the rear housing are formed by assembling left and right half housings with screws, and the mounting portion is provided with a screwing position in front of the control circuit board in a side view region of the rear housing. The screw tightening electric tool according to any one of claims 1 to 3 characterized by things.

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