WO2016158129A1

WO2016158129A1 - Electric tool

Info

Publication number: WO2016158129A1
Application number: PCT/JP2016/055839
Authority: WO
Inventors: 慎治倉賀野; 健熊倉
Original assignee: 日立工機株式会社
Priority date: 2015-03-30
Filing date: 2016-02-26
Publication date: 2016-10-06
Also published as: JP6508555B2; JPWO2016158129A1

Abstract

Provided is an electric tool equipped with a brushless motor- and drive circuit-cooling structure. The electric tool comprises a brushless motor, a housing with a motor-housing section for housing the motor, a fan driven by the motor to generate cooling air inside the housing, and a drive circuit for controlling the driving of the motor. The housing comprises an air intake vent, a discharge vent provided near the air intake vent, and an air channel demarcated between the two vents for cooling the brushless motor and the drive circuit using cooling air. The discharge vent and/or the air channel discharges the cooling air discharged from the discharge vent to the outside of the housing in a direction away from the air intake vent.

Description

Electric tool

The present invention relates to a power tool, and more particularly to a power tool having a cooling structure for a motor and a drive circuit.

In recent years, brushless motors have been used for electric circular saws for the purpose of reducing size and weight and increasing efficiency. When using a brushless motor, it is necessary to cool the drive circuit. Therefore, a drive circuit is arranged in an air passage provided in the housing, the motor and the drive circuit are cooled by cooling air flowing through the air passage from the intake air window of the housing, and the cooling air warmed by exhaust heat is discharged from the exhaust air window. The structure which discharges from is taken.

Japanese Patent No. 5633940

Depending on the structure of the housing, a part of the cooling air discharged from the housing after cooling the motor and the drive circuit may be sucked into the housing again. In this case, since the cooling air is higher than room temperature, the cooling efficiency of the drive circuit may be reduced.

Further, the cooling air may leak from the joints of a plurality of members constituting the housing, and the air volume may be reduced to reduce the cooling efficiency.

An object of the present invention is to provide an electric tool that efficiently cools a motor and a control circuit.

An electric power tool of the present invention is provided in a brushless motor, a housing having a motor housing portion that houses the brushless motor, a fan that is driven by the brushless motor and generates cooling air in the housing, and the housing. A drive circuit for controlling the drive of the brushless motor, and the housing has an intake air window into which the cooling air is sucked into the housing, and the intake air air for discharging the cooling air to the outside of the housing. An exhaust air window provided in the vicinity of the air window, and an air path defined for cooling the brushless motor and the drive circuit by the cooling air, the upstream end of the air path being Connected to the intake wind window, the downstream end is connected to the exhaust wind window, at least one of the exhaust wind window and the air path is The cooling air from the serial exhaust air window is discharged to the outside of the housing, and is configured to discharge in a direction away from the intake ventilation windows.

With the above configuration, the brushless motor and the driving circuit when driving the electric tool are cooled by the cooling air flowing from the air intake wind window through the air passage toward the exhaust air wind window. The cooling air that has become high temperature due to the exhaust heat is discharged in a direction away from the air intake wind window, so that intake of air into the air path through the air intake window again is suppressed. Thereby, since the cooling air containing exhaust heat does not flow into the air passage, the brushless motor and the drive board are continuously cooled by the cooling air at room temperature sucked from the air intake wind window.

Preferably, a disk-shaped saw blade connected to the brushless motor and driven, and a handle whose longitudinal direction extends in the side surface direction of the saw blade, the intake wind window and the exhaust wind window include: It is provided on the opposite side of the saw blade with respect to the handle.

With the above configuration, the cooling air is discharged from the exhaust wind window to the side opposite to the saw blade, so that it does not interfere with the cutting operation.

Preferably, the housing further includes a drive circuit housing portion that houses the drive circuit, and the motor housing portion and the drive circuit housing portion are arranged side by side along a side surface direction of the saw blade, One of the intake air window and the exhaust air window is provided in the motor housing portion, and the other is provided in the drive circuit housing portion.

With the above configuration, since the air passage is formed across the motor housing portion and the drive circuit housing portion, the brushless motor and the drive circuit can be efficiently cooled.

Preferably, the motor housing portion has a motor housing portion end surface on the anti-saw blade side, the drive circuit housing portion has a driving circuit housing portion end surface on the anti-saw blade side, and the motor housing portion end surface; The distance from the saw blade is substantially the same as the end face of the drive circuit housing portion.

With the above configuration, the electric tool can be placed on the work table so that the end surface of the motor housing portion and the end surface of the drive circuit housing portion are in contact with the surface of the work table. The blade can be easily replaced.

Preferably, the motor housing portion and the drive circuit housing portion are formed as separate members, and the motor housing portion and the drive circuit housing portion have a joint portion, and the motor housing portion and the drive circuit The inside of the housing portion is connected via the joint portion, and the air passage in the motor housing portion and the drive circuit housing portion is defined by the separate member.

With the above configuration, leakage of cooling air from the joint can be prevented.

Preferably, the intake air window is provided in the motor housing portion, and the exhaust air window is provided in the drive circuit housing portion.

With the above configuration, the cooling air is sucked from the air intake wind window and flows into the air passage, first the motor is cooled, then the drive board is cooled, and is discharged from the exhaust air window to the outside of the housing. Therefore, the motor and the drive board can be efficiently cooled.

Preferably, the exhaust air window is provided on an end surface of the drive circuit housing portion, and the drive circuit housing portion has an inclined portion that is inclined so as to be separated from the motor housing portion as it goes in the anti-saw blade direction. At least one of the exhaust air window and the air path is configured to discharge the cooling air in a direction away from the intake air window in cooperation with the inclined portion.

With the above configuration, it is possible to more reliably prevent the cooling air exhausted from the exhaust wind window from being sucked into the intake wind window again. Therefore, the brushless motor and the drive circuit can be efficiently cooled by the cooling air.

Preferably, an exhaust direction of the cooling air discharged from the exhaust wind window intersects an intake direction of the cooling air sucked in the intake wind window, and is between the intake wind window and the exhaust wind window. A part of the housing is interposed.

With the above configuration, it is possible to suppress the cooling air discharged from the exhaust wind window from being sucked into the intake wind window again.

According to the electric tool of the present invention, the brushless motor discharged from the exhaust wind window and the cooling air including the exhaust heat after cooling the drive circuit are prevented from being sucked again from the intake wind window. In addition, the drive circuit can be efficiently cooled.

The cross-sectional view of the electric power tool which is the 1st Embodiment of this invention. The top view of the electric tool shown in FIG. The right view of the electric tool shown in FIG. The left view of the electric tool shown in FIG. The rear view of the electric tool shown in FIG. The block diagram of the drive circuit of the electric tool shown in FIG. The top view of a control board provided with the drive circuit of FIG. The disassembled perspective view of a main housing and a motor housing. The disassembled perspective view of a main housing. The cross-sectional view of the electric tool which is the 2nd Embodiment of this invention.

A power tool 100 according to a first embodiment of the present invention will be described with reference to the drawings. In the drawing, the front is defined as the front direction, the rear as the rear direction, the upper direction as the upper direction, and the lower direction as the lower direction, the right as viewed from the rear direction as the right direction, and the left as the left direction. . Moreover, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. Furthermore, the embodiments do not limit the invention but are exemplifications, and all features and combinations described in the embodiments are not necessarily essential to the invention.

The electric tool 100 is provided with a housing 2 housing the brushless motor 1 and the control board 8, and a handle 3 having a switch 3 a in FIG. 4 for controlling the driving of the motor 1. And a disk-shaped saw blade 4 that is rotationally driven by the motor 1 and a shape that covers the upper half of the outer periphery of the saw blade 4 and is attached to the housing 2. A saw cover 5 for storing a part, and a bottom face 6a that is connected to the housing 2 via the saw cover 5 and that can slide on a material to be cut such as wood, and that can project the saw blade 4 downward from the bottom face 6a. A base 6 having a portion, a centrifugal fan 7 that is fixed to the output shaft 1a of the motor 1 and rotates by driving the motor 1 and cools the motor 1 by cooling air generated at the time of rotation, Some of 却風 has a cooling air discharge port 5c for discharging to the inside of the saw cover 5.

As shown in FIG. 6, the brushless motor 1 is a three-phase brushless DC motor including a stator 11, a rotor 12, and an output shaft 1a. The stator 11 is constituted by three-phase coils U, V, and W that are star-connected, and the coils U, V, and W are connected to the control board 8, respectively. The rotor 12 includes two sets of permanent magnets each having a north pole and a south pole, and a hall element 12A is disposed at a position facing the permanent magnet. The hall element 12 A outputs the position signal of the rotor 12 toward the rotor position detection circuit 33. The output shaft 1 a is a shaft extending in the left-right direction that is rotatably supported by the housing 2, and is rotated by driving of the motor 1. The output shaft 1a is connected to the saw blade 4 via a speed reduction mechanism (not shown), and the saw blade 4 rotates by the rotation of the output shaft 1a.

As shown in FIGS. 3 and 4, the power tool is provided with a safety cover 17 having a shape covering almost half of the outer periphery of the saw blade 4. The safety cover 17 is held in the saw cover 5 so as to be rotatable coaxially with the drive shaft 10 of the saw blade 4, and can be stored in the saw cover 5. The safety cover 17 is urged by an urging means such as a spring (not shown), and a rotation position that prevents most of the outer periphery of the saw blade 4 from being exposed because most of the portion protrudes below the bottom surface 6a of the base 6 is in an initial state. It has become. At the time of cutting work, the front end (right side in FIG. 3) of the safety cover 17 in the cutting direction comes into contact with the end of the material to be cut. When the power tool slides in the cutting direction in this state, the safety cover 17 rotates so as to be housed in the saw cover 5 against the spring, so that the saw blade 4 is exposed on the bottom surface 6a of the base 6. To do. In the case of a window extraction operation or the like in which a cutting process is performed on the upper surface of the material to be cut that is not continuous with the end surface, the safety cover 17 is also rotated by the operator operating the lever 17a and the saw blade 4 is moved on the bottom surface 6a of the base 6. Can be exposed. The drive shaft 10 to which the saw blade 4 is attached and fixed is interlocked with the output shaft 1a of the motor 1 through a gear mechanism.

The saw cover 5 as described above is connected to the base 6 so as to sandwich the saw blade 4 in the vicinity of both ends in the longitudinal direction of the base 6. A mechanism for adjusting the protruding amount of the saw blade 4 from the bottom surface of the base 6 by operating the lever 18 and a rotation surface of the saw blade 4 with respect to the base 6 (that is, the housing 2 is tilted with respect to the base 6). A mechanism is provided.

As shown in FIG. 6, a rectifying / smoothing circuit 20, a switching circuit 21, a current detection resistor 22, and a control unit 30 are mounted on the control board 8, and a drive circuit that controls driving of the brushless motor 1 is provided. It is composed. The rectifying / smoothing circuit 20 includes a diode bridge circuit 20A and a smoothing capacitor 20B. The input side is connected to the commercial AC power source P and the output side is connected to the switching circuit 21. As shown in FIG. 7, the diode bridge circuit 20 A and the smoothing capacitor 61 B are disposed on the control board 8. The rectifying / smoothing circuit 20 full-wave rectifies the AC voltage input from the commercial AC power supply P by the diode bridge circuit 20 A, smoothes it by the smoothing capacitor 20 B, and outputs it to the switching circuit 21.

The switching circuit 21 is arranged on the control board 8, and is composed of six FETs Q1 to Q6 connected in a three-phase bridge format. The gates of the FETs Q1 to Q6 are connected to the control unit 30, and the drains and sources of the FETs Q1 to Q6 are connected to the coils U, V, and W that are star-connected. The FETs Q1 to Q6 perform a switching operation according to the drive signal input from the control unit 30, and supply the DC voltage that has been full-wave rectified by the rectifying and smoothing circuit 20 to the coils U, V, and W as a three-phase voltage.

The current detection resistor 22 is a resistor for detecting a current flowing through the motor 1, and is connected between the rectifying / smoothing circuit 20 and the switching circuit 21.

As shown in FIG. 6, the control unit 30 includes a current detection circuit 31, a voltage detection circuit 32, a rotor position detection circuit 33, a control signal output unit 34, and a microcomputer 35.

The current detection circuit 31 takes in the voltage drop value of the current detection resistor 22 and outputs it to the microcomputer 35. The voltage detection circuit 32 detects a voltage applied to the motor 1 and outputs a signal indicating the detection voltage to the microcomputer 35. The rotor position detection circuit 33 outputs a position signal of the rotor 12 input from the hall element 12 A of the motor 1 to the microcomputer 35. The control signal output unit 34 is connected to each gate of the FETs Q1 to Q6, and applies a voltage to each gate of the FETs Q1 to Q6 based on a signal input from the microcomputer 35. Of the FETs Q1 to Q6, FETs to which a voltage is applied to the gate are turned on, and FETs to which no voltage is applied to the gate are turned off.

The microcomputer 35 is a central processing unit (CPU) for outputting a drive signal based on the processing program and data, a ROM for storing the processing program, control data, various threshold values, and the like, and a temporary storage for data. RAM. Further, the microcomputer 35 generates a drive signal for switching the FETs Q1 to Q6 based on the position signal of the rotor 12 input from the rotor position detection circuit 33, and outputs it to the control signal output unit 34. Accordingly, a predetermined coil among the coils U, V, and W is alternately energized to rotate the rotor 12 in a predetermined rotation direction. In this case, the drive signal output to the FETs Q1 to Q6 connected to the negative power supply side is output as a pulse width modulation signal (PWM signal).

Next, the housing 2 will be described with reference to FIGS. The housing 2 is obtained by combining the main housing 40, the motor housing 50, and the handle housing 60, which are formed of different members, and are integrated with each other.

The main housing 40 is made of a metal such as aluminum and supports the output shaft 1a of the motor 1 and a speed reduction mechanism that decelerates the rotation of the output shaft 1a and covers the upper half of the saw blade 4. A saw cover 5 is rotatably attached.

The motor housing 50 has a bottomed cylindrical shape that covers the motor 1 and the centrifugal fan 7. A bearing that supports one end of the output shaft 1 a of the motor 1 is held on the bottom 50 A of the motor housing 50. The bottom portion 50A corresponds to the end surface of the motor housing portion. The centrifugal fan 7 is disposed on the opposite side to the bottom 50A with respect to the motor 1. Further, the motor housing 50 is provided with a fan guide 51 so as to surround the outer periphery of the centrifugal fan 7 in an annular shape, so that the flow of cooling air generated by the centrifugal fan 7 can be induced. Furthermore, a first air window 52 having a plurality of slit-like openings that allow the motor housing portion to communicate with the outside is formed in the bottom portion 50 A of the motor housing 50.

The handle housing 60 includes a handle portion 61 provided above, and a drive circuit housing portion 62 that is formed below the handle portion and protrudes on the side opposite to the saw cover placement side. The handle portion 61 is combined with the main housing 40 to constitute the handle 3 whose longitudinal direction extends in the side surface direction of the saw blade 4.

As shown in FIGS. 1 and 9, the drive circuit accommodating portion 62 is formed in a bottomed cylindrical shape, and can accommodate the control board 8 in a direction in which the main surface intersects the side surface direction of the saw blade 4. Furthermore, a second wind window 63 having a plurality of slit-like openings that allow the drive circuit housing portion 62 to communicate with the outside is formed on the bottom 62A of the drive circuit housing portion 62. The bottom 62A corresponds to the end surface of the drive circuit housing portion. When the handle housing 60 is combined with the main housing 40, the drive circuit housing portion 62 is disposed on the opposite side of the saw blade 4 with respect to the handle 3 together with the motor housing 50 and along the side surface direction of the saw blade 4. Arranged side by side. At this time, in the vicinity of the second wind window 63, as shown in FIG. 1, an inclined portion 64 that inclines so as to move away from the motor housing in the anti-saw blade direction away from the motor housing 40 is formed in the second wind window 63. Extending to.

In the housing 2 configured as described above, when the motor housing 50 and the handle housing 60 are attached to the main housing 40, the first wind window 52 and the second wind window 63 are opposite to the saw blade 4 with respect to the handle 3. Placed on the side. Each of the motor housing 50 and the handle housing 60 has

wind windows

52 and 63, respectively. Further, in the housing 2, the motor housing 50 and the drive circuit housing portion 62 are connected to communicate with each other using the fan guide 51 as a joint portion.

When the motor housing 50 and the handle housing 60 are attached to the main housing 40, the distance from the saw blade 4 to the bottom 50 A of the motor housing 50 and the distance from the saw blade 4 to the bottom 62 A of the handle housing 60. Are formed so as to have substantially the same dimensions.

In the power tool 100 having the above-described configuration, at the time of cutting work, the operator grips the handle 3 and places the bottom surface 6a of the base 6 on the processing member to turn on the switch 3a to start the brushless motor 1, and the saw blade The processing member is cut by sliding the base 6 while rotating 4.

The cooling of the brushless motor 1 and the control board 8 after the brushless motor 1 is started are performed as shown in FIG. When the centrifugal fan 7 is rotated by the rotation of the motor 1, the cooling air is sucked from the first air window 52 of the motor housing 50 and introduced into the motor housing 50, passing through the motor 1 while cooling the motor 1, to the fan guide 51. Reach. A part of the cooling air is discharged to the saw cover 5 side through the cooling air discharge port 5c.

As the centrifugal fan 7 rotates, the cooling air is introduced into the adjacent drive circuit housing portion 62 by the fan guide 51 and mounted on the control board 8, the diode bridge circuit 20 A, the smoothing capacitor 20 B, and the switching element Q 1. Passing through the drive circuit housing portion 62 while cooling Q6, the second wind window 63 is reached. Thereafter, the cooling air passes through the second wind window 63 and is exhausted to the outside.

That is, an air path for cooling the brushless motor 1 and the control board 8 with cooling air is defined in the housing 2 with the first wind window 52 as an intake wind window and the second wind window 63 as an exhaust wind window. More specifically, in the air path defined in the housing 2 shown in FIG. 1, cooling air is introduced into the housing 2 using the first air window 52 as an intake air window, and the motor 1, the centrifugal fan 7, and the fan guide. 51 and the control board 8 pass through these components, and are exhausted out of the housing 2 from the second wind window 63 that is between the exhaust winds.

At this time, the cooling air exhausted from the second wind window 63 is exhausted in a direction in which the exhaust direction is separated from the first wind window 52 by the second wind window 63 and the inclined portion 64. Accordingly, the cooling air heated by the exhaust heat of the brushless motor 1 and the control board 8 can be prevented from being sucked again into the housing 2 from the first wind window 52, so that the cooling of the brushless motor 1 and the control board 8 can be efficiently performed. Can be done well.

Moreover, in the said structure, the motor housing 50 and the drive circuit accommodating part 62 are each provided with the separate member. Since the motor housing 50 communicates with the drive circuit housing portion 62 only through the opening of the motor housing 50 in which the fan guide 51 is provided, the cooling air that has flowed into the drive circuit housing portion 62 through the fan guide 51. However, it can suppress that it leaks from parts other than the 2nd wind window 63 except the cooling wind discharge port 5c.

Further, the cooling air discharged from the second wind window 63 by the inclined portion 64 formed in the vicinity of the second wind window 63 is more separated from the first wind window 52 than in the case where the inclined portion 64 is not provided. To be discharged. Therefore, the effect of suppressing re-inflow into the first wind window 52 can be enhanced by the inclined portion 64.

In addition, the inclined portion 64 forms a part of the drive circuit housing portion 62 to demarcate the air path, and is provided between the first air window 52 and the second air window 63, and thus the second air window. Since this is an obstacle to the cooling air discharged from 63, it is possible to enhance the effect of suppressing re-inflow into the first wind window 52.

Furthermore, even if the opening as the second wind window 63 is formed in parallel with the side surface direction of the saw blade 4, the direction of the cooling air discharged from the second wind window 63 is changed by the inclined portion 64 to the first wind window. The direction can be away from 52.

Furthermore, since the first wind window 52 and the second wind window 63 are provided on the side opposite to the saw blade 4 with respect to the handle 3, the chips of the processing member are the first wind window 52 or the second wind window 63. Can be prevented from entering the inside of the housing 2.

In the above-described embodiment, the inclined portion 64 is provided in the drive circuit housing portion 62. However, as shown in the electric power tool 100 which is another embodiment shown in FIG. Similarly to the embodiment, the cooling air exhausted from the second air window 63 is exhausted in a direction away from the first air window 52, and the inflow into the housing 2 from the first air window 52 is suppressed.

Even if the centrifugal fan 7 is replaced with an axial fan and the brushless motor 1 is driven, an air path is defined in which the second wind window 63 is used as an intake wind window and the first wind window 52 is used as an exhaust wind window. good. In this case, the cooling air is cooled in the order of the control board 8 and the brushless motor 1, and is discharged from the first air window 52 in a direction away from the second air window 63. Even in this case, since the cooling air heated by the exhaust heat is suppressed from being sucked into the housing 2 again, the brushless motor 1 and the control board 8 can be efficiently cooled.

The present invention is not limited to the power tool of the above-described embodiment, but can be applied to a brushless motor housed in a housing and an appropriate power tool that requires cooling of the drive circuit with cooling air.

DESCRIPTION OF SYMBOLS 1 ... Brushless motor, 2 ... Housing, 3 ... Handle, 4 ... Saw blade, 7 ... Fan, 8 ... Control board as drive circuit, 40 ... Main housing, 50 ... Motor housing as motor accommodating part, 52 ... 1st , 62 ... drive circuit housing part, 63 ... second wind window, 64 ... inclined part, 100 ... electric power tool

Claims

A brushless motor, a housing having a motor housing for housing the brushless motor, a fan driven by the brushless motor to generate cooling air in the housing, and provided in the housing for driving the brushless motor. A drive circuit for controlling, and the housing is provided close to the intake air window for discharging the cooling air to the outside of the housing, and an intake air window into which the cooling air is sucked into the housing. An exhaust air window, and an air passage defined for cooling the brushless motor and the drive circuit with the cooling air, the air passage having an upstream end connected to the intake air window, A downstream end is connected to the exhaust wind window, and at least one of the exhaust wind window and the air path is located in front of the exhaust wind window. Power tool, characterized in that it is configured to discharge the cooling air is discharged to the outside of the housing, in a direction away from the intake ventilation windows.
A disk-like saw blade connected to and driven by the brushless motor; and a handle having a longitudinal direction extending in a lateral direction of the saw blade. The intake wind window and the exhaust wind window are connected to the handle. The power tool according to claim 1, wherein the power tool is provided on an opposite side of the saw blade.
The housing further includes a drive circuit housing portion that houses the drive circuit, and the motor housing portion and the drive circuit housing portion are arranged side by side along a side surface direction of the saw blade, 3. The power tool according to claim 2, wherein one of the exhaust air window and the exhaust air window is provided in the motor housing portion, and the other is provided in the drive circuit housing portion.
The motor accommodating portion has a motor accommodating portion end surface on the anti-saw blade side, the drive circuit accommodating portion has a driving circuit accommodating portion end surface on the anti-saw blade side, the motor accommodating portion end surface, and the drive circuit The power tool according to claim 3, wherein the distance from the saw blade is substantially the same as the housing end surface.
The motor housing portion and the drive circuit housing portion are formed as separate members, and the motor housing portion and the drive circuit housing portion have a joint, and the motor housing portion and the drive circuit housing portion The power tool according to claim 3, wherein the air path is connected by the joint portion, and the air passage in the motor housing portion and the drive circuit housing portion is defined by the separate member.
The power tool according to any one of claims 3 to 5, wherein the intake air window is provided in the motor housing portion, and the exhaust air window is provided in the drive circuit housing portion.
The exhaust wind window is provided on an end surface of the drive circuit housing portion, and the drive circuit housing portion has an inclined portion that is inclined so as to be separated from the motor housing portion toward the anti-saw blade direction. At least one of the air window and the air path is configured to discharge the cooling air in a direction away from the intake air window in cooperation with the inclined portion. Item 7. The electric tool according to Item 6.
The exhaust direction of the cooling air exhausted from the exhaust wind window intersects the intake direction of the cooling air sucked in by the intake wind window, and between the intake wind window and the exhaust wind window, The power tool according to any one of claims 1 to 6, wherein a part of the power tool is interposed.