JP2014100787A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool capable of reducing heat protective countermeasures for an electronic component by separating a switching element from the electronic component such as a microcomputer without increasing the overall dimension of the power tool.SOLUTION: A power tool comprises a DC brushless motor 20 as a driving source, and controls the DC brushless motor 20 with a switching element 44. The power tool comprises: a cylindrical housing body 12 where the DC brushless motor 20 is housed; and a grip part 15 projecting from a side part of the housing body 12. The switching element 44 is arranged inside the grip part 15, and separated from an electric circuit board 50 for electronic components to operate the switching element 44.

Description

  The present invention relates to an electric tool configured to use a DC brushless motor as a drive source and to control the DC brushless motor by a switching element.

In an electric tool that controls a DC brushless motor using a switching element, it is generally performed to arrange the switching element behind the DC brushless motor. However, in the configuration in which the switching element is arranged behind the DC brushless motor, there is a problem that the overall length of the electric tool is increased and the usability of the electric tool is deteriorated.
In order to solve this problem, in the electric power tool described in Patent Document 1, the switching element is assembled to the electric circuit board together with the electronic components and arranged at the protruding end of the grip portion. Thereby, it is not necessary to provide a space for the switching element behind the DC brushless motor, and the overall length of the electric tool can be made relatively small.

JP 2007-283447 A

  However, in the electric power tool described in Patent Document 1, since the switching element and an electronic component such as a microcomputer that operates the switching element are assembled on the same electric circuit board, the electronic component is caused by the heat of the switching element. Thermal protection measures are required so that they are not affected.

  The present invention has been made to solve the above problems, and the problem to be solved by the present invention is that the switching element can be separated from an electronic component such as a microcomputer without increasing the overall length of the electric power tool. By doing so, it is to reduce heat protection measures for the electronic component.

The above-described problems are solved by the inventions of the claims.
The invention of claim 1 is a power tool configured to use a DC brushless motor as a drive source and to control the DC brushless motor by a switching element, and a cylindrical housing body portion in which the DC brushless motor is housed, A grip portion protruding from a side portion of the housing main body portion, and the switching element is disposed inside the grip portion and separated from an electronic circuit board for an electronic component that operates the switching element. It is characterized by that.

According to the present invention, the switching element is disposed inside the grip portion and is separated from the electronic circuit board for the electronic component that operates the switching element. For this reason, it becomes difficult for the heat of a switching element to be transmitted to an electronic component, and the heat protection measure with respect to an electronic component can be reduced.
Moreover, since the switching element is disposed inside the grip portion, it is not necessary to provide a space for the switching element behind the DC brushless motor, and the overall length of the electric tool does not increase.

  According to the invention of claim 2, the battery pack connecting portion to which the battery pack is detachably connected is formed at the projecting end of the grip portion, and the electronic circuit board for the electronic component is disposed in the space of the grip portion. And it is arrange | positioned along the said battery pack connection part, It is characterized by the above-mentioned.

According to the invention of claim 3, the switching element is mounted on the power circuit board, and the power circuit board is substantially the same as the board surface of the motor board mounted on the end face of the DC brushless motor. It is positioned along the longitudinal direction of the grip portion in a state where the direction is directed, and both end edges in the width direction of the power circuit board are supported by the inner wall surface of the grip portion.
According to the present invention, both ends of the power circuit board on which the switching element is mounted are supported by the inner wall surface of the grip portion in the width direction. For this reason, the contact area between the power circuit board and the grip portion is reduced, and the heat of the switching element is hardly transmitted to the grip portion.
Moreover, since the board surface of the power circuit board is oriented in substantially the same direction as the board surface of the motor board mounted on the end face of the DC brushless motor, the power circuit board (switching element) and the motor board (DC Twisting of power lines connecting brushless motors is prevented, and the wiring space can be made compact.

According to the invention of claim 4, the switching element is covered with a heat radiating material or a heat insulating material.
For this reason, it becomes difficult for the heat of a switching element to be transmitted to a grip part.
According to the invention of claim 5, the inner wall surface of the grip portion is covered with a heat radiating material or a heat insulating material.
For this reason, it becomes difficult for the heat of a switching element to be transmitted to a grip part.

  According to the present invention, by disposing the switching element in the grip portion away from the electronic component such as the microcomputer, it is possible to reduce thermal protection measures for the electronic component without increasing the overall length of the electric tool.

It is a longitudinal cross-sectional view of the electric tool which concerns on Embodiment 1 of this invention. It is drawing which shows the structure of the drive circuit of DC brushless motor. It is a rear view of a motor board and a power circuit board of a DC brushless motor.

[Embodiment 1]
Hereinafter, the power tool according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The electric tool according to the present embodiment is a rotary impact tool (impact driver) using a DC brushless motor as a drive source. Here, FIG. 1 is a longitudinal sectional view of the electric power tool according to the first embodiment, and FIG. 2 is a drawing showing a configuration of a drive circuit of the DC brushless motor. FIG. 3 is a rear view of the motor board and power circuit board of the DC brushless motor.

<About the outline of electric tools>
As shown in FIG. 1, the housing 11 of the electric power tool 10 according to the present embodiment is formed so as to protrude from a cylindrical housing main body portion 12 and a side portion (lower portion in FIG. 1) of the housing main body portion 12. And a grip portion 15. The grip portion 15 includes a grip portion 15h that is gripped when the user uses the electric power tool 10, and an exposed portion 15p that is located on the protruding end (lower end) side of the grip portion 15h. The grip portion 15h is formed with a relatively small diameter so that the user can easily grip it. A trigger-type switch lever 15r that is pulled by a user with a fingertip is provided at the proximal end of the grip portion 15h.
The exposed portion 15p of the grip portion 15 is configured to expand in the front-rear direction with respect to the grip portion 15h, and a battery pack in which a battery pack (not shown) is connected to the lower side of the exposed portion 15p. A connecting portion 16 is provided.

  In the housing main body 12, a DC brushless motor 20, a planetary gear mechanism 24, a spindle 25, a striking force generation mechanism 26, and an anvil 27 are accommodated coaxially in this order from the rear side. Then, the rotation of the DC brushless motor 20 is transmitted to the spindle 25 through the planetary gear mechanism 24, and the rotational force of the spindle 25 is converted into the rotational striking force by the striking force generating mechanism 26 and transmitted to the anvil 27. The anvil 27 is supported by a bearing 12j provided at the tip of the housing body 12 so as to be rotatable about the axis and not to be displaced in the axial direction. A chuck portion 27t for mounting a driver bit, a socket bit or the like (not shown) is provided at the tip of the anvil 27.

<About DC brushless motor 20>
As shown in FIG. 1, the DC brushless motor 20 includes a rotor 22 having a permanent magnet and a stator 23 having a drive coil 23c. The stator 23 includes a cylindrical portion (not shown) and six tooth portions 23p protruding radially inward from the inner peripheral surface of the cylindrical portion, and these tooth portions 23p are the rotor 22. Are arranged at equal intervals around. The drive coil 23c is wound around each tooth portion 23p with an insulating member interposed therebetween.
Further, a magnetic sensor 32 for detecting the position of the magnetic pole of the rotor 22 is attached to the rear end portion of the stator 23 via a motor board 33 (described later). As a result, the rotor 22 can be rotated by causing the magnetic sensor 32 to detect the position of the magnetic poles of the rotor 22 and causing the drive circuit 40 to be described later to pass current through each drive coil 23c in order.

<About magnetic sensor 32>
The magnetic sensors 32 are used as a set of three, and the three magnetic sensors 32 are arranged at equal intervals in the circumferential direction. The three magnetic sensors 32 are attached to a ring-shaped motor substrate 33 shown in FIG. 3, and the motor substrate 33 is coaxial with the stator 23 of the DC brushless motor 20, and the stator 23 is placed behind the stator 23. It is screwed to the end (see FIG. 1).
Further, the motor substrate 33 is provided with a relay portion T (see FIG. 3) for connecting a winding of the drive coil 23c and a power line 41 (described later).

<About the drive circuit 40>
As shown in FIG. 2, the drive circuit 40 of the DC brushless motor 20 includes a power supply circuit unit 42, a three-phase bridge circuit unit 45 including six switching elements 44, and switching of the three-phase bridge circuit unit 45. And a control circuit unit 46 for controlling the element 44. The power supply circuit unit 42 is a part that receives power supplied from the battery 42v in the battery pack to the electric tool 10 via the terminal 42t of the battery pack coupling unit 16. The power supply circuit unit 42 includes a power supply line 42c connected to the terminal 42t, a power supply smoothing capacitor 43c connected in parallel to the power supply line 42c, and a current detection connected in series to the power supply line 42c. The shunt resistor 43s.
The three-phase bridge circuit unit 45 is connected to the power supply line 42c in parallel with the power supply smoothing capacitor 43c, and three output lines 41 (hereinafter referred to as power lines 41) of the three-phase bridge circuit unit 45 are connected. As described above, it is connected to the winding of the corresponding drive coil 23 c via the relay portion T of the motor substrate 33. Here, as the switching element 44 of the three-phase bridge circuit unit 45, for example, a field effect transistor (FET) is used.

The control circuit unit 46 is configured by an electronic component such as a microcomputer or an IC that operates the switching element 44. The control circuit unit 46 receives the signals of the three magnetic sensors 32 described above, and controls on / off of each switching element 44 constituting the three-phase bridge circuit unit 45 based on the signals (see white arrows). . As a result, a current can be passed through each of the drive coils 23c of the stator 23 in order.
The control circuit 46 receives signals from various switches 46a and 46b for switching the tightening speed and turning on / off the tool light. Further, the control circuit unit 46 incorporates LEDs 46x and 46y for displaying a tightening speed, a battery capacity, and the like.
The drive circuit 40 of the DC brushless motor 20 is installed in the grip portion 15 by an electronic circuit board 50 and a power circuit board 60.

<About the electronic circuit board 50>
The electronic circuit board 50 is a board on which the control circuit unit 46 of the drive circuit 40, various switches 46a and 46b, and LEDs 46x and 46y are mounted. As shown in FIG. 1, the electronic circuit board 50 is attached inside the exposed portion 15 p of the grip portion 15 and laid down along the upper surface of the battery pack connecting portion 16.
Here, on the front surface of the exposed part 15p of the grip part 15, an operation part (not shown) for operating various switches 46a, 46b and a display confirmation part (for example, a display of various LEDs 46x, 46y can be confirmed) Transparent portion).

<About the power circuit board 60>
The power circuit board 60 is a board on which the six switching elements 44 constituting the three-phase bridge circuit unit 45, the power smoothing capacitor 43c of the power circuit unit 42, the shunt resistor 43s, and the like are mounted. As shown in FIG. 1, the power circuit board 60 is located inside the grip portion 15 h of the grip portion 15 with the board surface facing the front of the electric tool 10 like the board surface of the motor board 33. It is positioned in a standing state (a state along the longitudinal direction of the grip portion 15h). The left and right edges of the power circuit board 60 are supported by the inner wall surface of the grip portion 15 h of the grip portion 15.

Three switching elements 44 are attached to the front surface of the power circuit board 60 in a state of being vertically arranged at a predetermined interval, and a power supply smoothing capacitor 43c is disposed at the lower part of the front surface of the board. ing. Also, as shown in FIG. 3, three switching elements 44 are similarly attached to the rear surface of the power circuit board 60 in a vertically arranged state with a predetermined interval. A shunt resistor 43s is disposed at the lower part. Furthermore, as shown in FIG. 1, the surface of the switching element 44 attached to the front surface and the rear surface of the power circuit board 60 is covered with, for example, a heat sink 65 made of aluminum alloy.
The power circuit board 60 and the electronic circuit board 50 are electrically connected by a flexible control cable 62.
Further, as shown in FIG. 3, one end of the power supply line 42c of the drive circuit 40 is connected to the power circuit board 60, and the other end of the power supply line 42c is connected to the battery as shown in FIG. It is connected to the terminal 42 t of the pack connecting part 16. Further, the power circuit board 60 and the relay portion T of the motor board 33 are connected by three power lines 41 arranged substantially in parallel as shown in FIG. Here, since the power circuit board 60 and the motor board 33 are both directed forward, the three power lines 41 are not twisted, and the wiring space can be made compact. .

<Advantages of the electric power tool 10 according to the present embodiment>
According to the electric power tool 10 according to the present embodiment, the switching element 44 is disposed inside the grip portion 15 and separated from the electronic circuit board 50 for electronic components that operates the switching element 44 as shown in FIG. ing. For this reason, it becomes difficult for the heat of the switching element 44 to be transmitted to the microcomputer or the like (electronic component) of the control circuit unit 46, and the heat protection measures for the electronic component can be reduced.
Further, since the switching element 44 is disposed inside the grip portion 15, it is not necessary to provide a space for the switching element 44 behind the DC brushless motor 20, and the overall length of the electric tool 10 does not increase.

Furthermore, since both ends of the power circuit board 60 in the width direction are supported by the inner wall surface of the grip part 15, the contact area between the power circuit board 60 and the grip part 15 is reduced, and the heat of the switching element 44 is reduced. Is difficult to be transmitted to the grip portion 15.
Further, since the board surface of the power circuit board 60 is oriented in substantially the same direction as the board surface of the motor board 33 mounted on the end face of the DC brushless motor 20, the power circuit board 60 (switching element 44) and The three power lines 41 connecting the motor substrate 33 (DC brushless motor 20) are not easily twisted, and the wiring space can be made compact.
Moreover, since the switching element 44 is covered with the heat sink 65 (heat radiating material) made of an aluminum alloy, the switching element 44 is unlikely to reach a high temperature, and the heat of the switching element 44 is not easily transmitted to the grip portion 15.

<Example of change>
Here, the present invention is not limited to the above-described embodiment, and can be modified without departing from the gist of the present invention. For example, in the present embodiment, an example in which the switching element 44 is covered with the heat sink 65 made of an aluminum alloy is shown, but a configuration in which the inner wall surface of the grip portion 15 is covered with a heat insulating material instead of providing the heat sink 65 is also possible. . Further, a configuration in which the switching element 44 is covered with a heat radiating plate 65 made of an aluminum alloy and the inner wall surface of the grip portion 15 is covered with a heat insulating material is also possible. Moreover, the structure which covers the switching element 44 with a heat insulating material instead of covering with the heat sink 65 is also possible.
Further, in the present embodiment, an example in which three switching elements 44 are attached to the front surface and the rear surface of the power circuit board 60 is shown. However, two power circuit boards are prepared and each power circuit board is formed. In addition, a configuration in which three switching elements 44 are attached to each other is possible. Thereby, the cooling efficiency of the switching element 44 can be improved.
In the present embodiment, an impact driver is exemplified as the power tool 10, but the present invention can also be applied to power tools other than the impact driver.

10 ... Electric tool 12 ... Housing body 15 ... Grip 15h ... Grip part 16 ... Battery pack connecting part 20 ... DC brushless motor 33 ... Motor board 40 ... Drive circuit 44 ... Switching element 46 ... Control circuit unit 50 ... Electronic circuit board 60 ... Power circuit board 65 ... Heat sink

The invention according to claim 1 is a DC brushless motor having a stator and a rotor, a housing main body portion that accommodates the DC brushless motor, a grip portion that is provided below the housing main body portion, A power tool having a battery pack connecting portion provided below and having a terminal, a first circuit board having a microcomputer, and a second circuit board having six switching elements, wherein the second circuit The substrate is connected to two power lines and three output lines connected to the driving coil of the stator .

According to the present invention, the switching element is provided on the second circuit board and is separated from the microcomputer provided on the first circuit board . Therefore, heat of the switching element is not easily transmitted to the microcomputer or the like, can be reduced thermal protection for the electronic components such as a microcomputer.

According to the invention of claim 2, three switching elements are mounted on one surface of the second circuit board, and three switching elements are mounted on the opposite surface of the second circuit board. It is characterized by being.

<About the electronic circuit board 50>
The electronic circuit board 50 is a board on which the control circuit unit 46 of the drive circuit 40, various switches 46a and 46b, and LEDs 46x and 46y are mounted. As shown in FIG. 1, the electronic circuit board 50 is attached inside the exposed portion 15 p of the grip portion 15 and laid down along the upper surface of the battery pack connecting portion 16.
Here, on the front surface of the exposed part 15p of the grip part 15, an operation part (not shown) for operating various switches 46a, 46b and a display confirmation part (for example, a display of various LEDs 46x, 46y can be confirmed) Transparent portion).
That is, the electronic circuit board 50 corresponds to the first circuit board of the present invention.

<About the power circuit board 60>
The power circuit board 60 is a board on which the six switching elements 44 constituting the three-phase bridge circuit unit 45, the power smoothing capacitor 43c of the power circuit unit 42, the shunt resistor 43s, and the like are mounted. As shown in FIG. 1, the power circuit board 60 is located inside the grip portion 15 h of the grip portion 15 with the board surface facing the front of the electric tool 10 like the board surface of the motor board 33. It is positioned in a standing state (a state along the longitudinal direction of the grip portion 15h). The left and right edges of the power circuit board 60 are supported by the inner wall surface of the grip portion 15 h of the grip portion 15.
That is, the power circuit board 60 corresponds to the second circuit board of the present invention.

Claims (5)

An electric tool configured to use a DC brushless motor as a drive source and to control the DC brushless motor by a switching element,
A cylindrical housing main body in which the DC brushless motor is housed, and a grip portion protruding from a side portion of the housing main body,
The electric power tool characterized in that the switching element is disposed inside the grip portion and is separated from an electronic circuit board for an electronic component that operates the switching element. The electric tool according to claim 1,
A battery pack connecting portion to which the battery pack is detachably connected is formed at the protruding end of the grip portion,
The electric circuit board for the electronic component is disposed in the space of the grip portion and along the battery pack connecting portion. The electric tool according to claim 1 or 2,
The switching element is mounted on a power circuit board;
The power circuit board is positioned along the longitudinal direction of the grip portion with the board surface oriented in substantially the same direction as the board surface of the motor board mounted on the end face of the DC brushless motor. ,
A power tool characterized in that both end edges in the width direction of the power circuit board are supported by an inner wall surface of the grip portion. The electric tool according to any one of claims 1 to 3,
The electric power tool, wherein the switching element is covered with a heat radiating material or a heat insulating material. The electric tool according to any one of claims 1 to 4, wherein
An electric tool characterized in that an inner wall surface of a grip part is covered with a heat radiating material or a heat insulating material.

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