JP2012096300A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool enabling its motor to be mostly normally conducted with electricity.SOLUTION: The power tool includes: a housing; a motor having a stator fixed to the housing and a rotor rotatable relative to the stator; and a permanent magnet fixed to the rotor. A first magnetism detecting element is prepared at a position where it faces the permanent magnet, and a second magnetism detecting element is prepared at a position where it faces the permanent magnet. Here, the first magnetism detecting element detects rotation of the motor, and the second magnetism detecting element conducts electricity to the motor. Thus, the problem is solved.

Description

  The present invention relates to a power tool. In particular, the present invention relates to an electric tool having a motor and capable of detecting the rotation of the motor.

  As a conventional electric tool, as shown in FIG. 1 of Patent Document 1, there is one in which a magnet 5 is attached to a shaft 3 of a motor 2 and a magnetic detection element 6 is provided at a position facing the magnet 5. .

JP-A-60-104668

  In the electric tool disclosed in Patent Document 1 described above, the motor 2 is energized by the switch 11. However, this switch energizes the motor by mechanically connecting circuit contacts. For this reason, the contact may not be connected due to friction or the like when the circuit is connected, and the motor may not be normally energized. In this case, the motor does not rotate.

  An object of the present invention is to provide an electric tool that can reduce the failure of normal energization of a motor as described above.

  The object is to provide a motor having a housing, a stator fixed to the housing, a rotor rotatable with respect to the stator, and a magnet fixed to the rotor. An electric tool having a first magnetic detection element at a position facing the magnet, a second magnetic detection element at a position facing the magnet, and the first magnetic detection element, This can be achieved by an electric tool characterized in that the rotation of the motor is detected and the motor is energized by the second magnetic detection element.

  According to the electric tool described in the first aspect, it is possible to provide an electric tool that can reduce the possibility that the motor is not normally energized.

The partial cross section figure of the electric driver which shows the 1st Embodiment of this invention

  FIG. 1 shows a partial cross-sectional view of an electric screwdriver 1 showing a first embodiment of the electric power tool of the present invention.

  The structure of the 1st Embodiment of this invention is demonstrated using FIG.

  The electric driver 1 has a housing 2 that is an outer frame. The housing 2 includes a cylindrical portion 2A extending in the front-rear direction, a tail portion 2B provided behind the cylindrical portion 2A, a first rib 2C provided integrally with the cylindrical portion 2A, a second rib 2D, A wind window 2E that spatially connects the inside and the outside of the housing 2 is provided.

  An electric motor 3 is provided at the rear of the cylindrical portion 2A. The motor 3 is a direct current brushless motor. The motor 3 includes a stator 3A that is fixed to the inner peripheral surface of the cylindrical portion 2A, and a rotor 3B that rotates with respect to the stator 3A. A coil 3A1 is wound around the stator 3A and fixed. A magnet 3B1 is fixed to the rotor 3B with an adhesive. When the coil 3A1 is energized, the magnet 3B1 receives a rotational force by the magnetic field from the coil 3A1. A motor shaft 3C is provided as a rotation shaft of the rotor 3B.

  A first bearing 5A, which is a bearing, is provided at the front of the motor shaft 3C. A second bearing 5B, which is a bearing, is provided at the rear portion of the motor shaft 3C. The first bearing 5A is held by the first rib 2C, and the second bearing 5B is held by the second rib 2D.

  A pinion 10 that is a gear is fixed to the front end of the motor shaft 3C. Three planetary gears 11 are provided so as to mesh with the pinion. A clutch or the like (not shown) is disposed in the front portion of the planetary gear 11 and inside the cylindrical portion 2A, and is connected to the output shaft 12. The output shaft 12 protrudes from the front end of the cylindrical portion 2A so that a predetermined tip tool (for example, a plus bit) can be attached.

  A cooling fan 20 is fixed to the rear end of the motor shaft 3C. The cooling fan 20 is provided with a fan blade 20A. The cooling fan 20 is provided with a thin circular magnet 21. The magnet 21 is provided with four poles, N pole, S pole, N pole, and S pole. These four poles are provided with an N pole at a 0 degree position, a S pole at a 90 degree position, an N pole at a 180 degree position, and an S pole at a 270 degree position. The cooling fan 20 can take in outside air from the outside of the housing via the wind window 2E provided in the tail portion 2B. The outside air can cool the power circuit board, the inverter circuit board, the motor, and the like.

  A lever 4 is provided on the upper portion of the cylindrical portion 2A so as to be movable with respect to the cylindrical portion 2A. The lever 4 includes an operation portion 4A provided at the front portion, a rotation shaft provided at the rear of the operation portion, 4B, and a bent portion 4C provided at the rear of the rotation shaft 4B. A coil spring 6 that is an elastic body is provided between the operation portion 4A and the cylindrical portion 2A. The lever 4 is biased clockwise by the coil spring 6.

  A tail portion 2B is provided so as to partially overlap the cylindrical portion 2A in the front-rear direction.

  A first Hall IC is provided on the front side of the bent portion 4C. The first Hall IC is arranged at a position facing the magnet 21. Further, when the operation portion 4A of the lever 4 is operated, the distance between the magnet 21 and the first Hall IC is increased. The first Hall IC is connected to the power circuit board 31 with a cord. The power supply circuit board 31 is equipped with a diode bridge for converting alternating current into direct current, a capacitor for performing rectification, a control unit (microcomputer) for performing various controls, and the like.

  A forward / reverse selector switch 24 is provided below the cylindrical portion 2A. The forward / reverse changeover switch 24 can arbitrarily switch the rotation direction of the rotor 3B between the forward rotation direction and the reverse rotation direction. The forward / reverse selector switch 24 is connected to the inverter circuit board 32 by a cord. A plurality of switching elements are mounted on the inverter circuit board 32.

  A second Hall IC is provided so as to be connected to the inverter circuit board 32. The second Hall IC is disposed at a position facing the magnet 21.

  The inverter circuit board 32 and the above-described coil 3B1 are connected. The coil 3B1 is energized by energization from the switching element of the inverter circuit board 32.

  The inverter circuit board 32 and the power circuit board 31 are connected by a cord. A power cord 30 is provided so as to be connected to the power circuit board 31. The power cord 30 protrudes from the tail portion 2B, and the power cord 30 is provided with a plug that can be plugged into a commercial power outlet.

  In addition, a hook 40 is provided at the rear part of the tail part 2B so that it can be hooked on or hooked to a predetermined object.

  The operation of the electric driver 1 having the above structure will be described.

  With the plug inserted into the outlet, the operator holds the cylindrical portion 2A and puts the forward / reverse selector switch 24 in the predetermined direction. When the operation portion 4A is operated, the coil spring 6 is compressed and comes close to the operation portion 4Aga tubular portion 2A. Then, since the lever 4 rotates about the rotation shaft 4B as the rotation center, the bent portion 4C is separated from the cooling fan 20. Then, the first Hall IC that has been close to the magnet 21 is separated. For this reason, the signal at the time of moving away from this proximity is transmitted to the power circuit board. In practice, this signal is transmitted as a potential difference.

  In response to this signal, the coil is energized by the switching element. For this reason, receiving the magnetic field of the coil, the rotor 3B having the magnet 3B1 rotates. When the rotor 3B rotates, the pinion 10 rotates, the planetary gear 11 rotates, and the output shaft 12 connected to the planetary gear rotates. By rotating the output shaft, a predetermined work can be performed by a tip tool or the like.

  In addition, the number of rotations of the rotor 3B can be grasped by the second Hall IC arranged at a position facing the magnet 21. Since the three second Hall ICs are provided with a predetermined interval of 60 degrees, the proximity and separation from the magnet 21 are detected. Thereby, the rotation speed can be grasped. Since the rotational speed can be grasped in this way, feedback control can be performed so that the rotational speed is constant.

  Thus, the magnet 21 fixed to the cooling fan 20 can output a signal for energizing the motor provided in the lever 4, and the rotation speed of the rotor 2 </ b> B can be output by the magnet 21. Can be grasped.

  In addition, since the magnet 21 is fixed to the cooling fan 21, it is configured to be compact.

  Moreover, since Hall IC23 and HallIC22 are arrange | positioned behind the magnet 21, it does not become large in radial direction.

  Further, since the magnet 21 different from the magnet 3B1 rotated by the magnetic field of the coil is used, signals can be output to the Hall IC 22 and the Hall IC 23 with high accuracy.

  Examples of modifications of the embodiment of the present invention include the following. Note that the effect of the present invention can also be achieved in this modification.

  Modification 1: In the first embodiment of the present invention, a magnet 21 different from the rotor magnet 3B1 is provided. However, the magnet of the rotor may be arranged at a position facing the Hall IC 22 and the Hall IC 23. In this way, it is not necessary to provide another magnet in addition to the rotor magnet.

  Modification 2: Although there is only one second Hall IC 23, a plurality of second Hall ICs 23 may be provided. In this way, the operation of the operation unit 4A can be detected with high accuracy.

1 Electric Driver, 2 Housing, 3 Motor, 4 Lever, 12 Output Shaft, 20 Cooling Fan, 21 Magnet, 22 Hall IC, 23 Hall IC, 30 Power Cord, 31 Power Cord, 32 Inverter Circuit Board

Claims (4)

A housing;
A motor having a stator fixed to the housing and a rotor rotatable with respect to the stator;
A power tool having a magnet fixed to the rotor,
A power tool comprising a first magnetic detection element for detecting rotation of the motor and a second magnetic detection element for turning on and off the switch at a position facing the magnet.   The electric tool according to claim 1, wherein the magnet is fixed to a fan fixed to the rotor. An output shaft connected to the rotor protrudes from the front part of the housing,
The electric tool according to claim 1 or 2, wherein the first magnetic detection element and the second magnetic detection element are provided behind the magnet. A housing;
A motor having a stator fixed to the housing and a rotor rotatable with respect to the stator;
A power tool having a magnet fixed to the rotor,
A power tool characterized in that a magnetic detection element for turning on and off a switch is provided at a position facing the magnet.