JP5370809B2 - Electric tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool capable of attaining a good cooling structure with a switching element installed at a position distant from a motor. <P>SOLUTION: The power tool includes the motor 3, a fan 18 mounted on a rotating shaft of the motor 3 to cool the motor 3, rotation transmitting means (4, 5) for transmitting a rotational force or a driving force to a front end tool, and a housing 6 for storing them. The housing 6 comprises a body portion 6a for storing the motor 3 and the rotation transmitting means, a handle 6b extending downward from the body portion 6a, and a battery retainer 6c at a front end of the handle 6b. A control circuit for controlling the rotation of the motor 3 is disposed on a substrate 9 mounted on the handle or the battery retainer and an air inlet/outlet 25 is provided in the battery retainer 6c to cool the control circuit by generating air flows (30a to 30f) in the handle 6b using the fan 18. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electric power tool that uses a motor as a drive source and has improved cooling efficiency of an electric circuit for control.

  2. Description of the Related Art In recent years, a fan is provided for cooling a motor in an electric tool that performs a required work by rotationally driving a tip tool such as a drill or a driver with a motor. The fan is provided coaxially with the motor and rotates with the rotation of the motor. Usually, the fan is provided on the rear end side or the front end side of the rotation shaft of the motor, and the heat generation portion of the motor is cooled by the air flow generated by the fan. In an electric tool using a brushless DC motor, an inverter circuit composed of an output transistor or the like is provided at the rear of the motor, for example, to rotate a rotor by sequentially energizing a predetermined coil with electric power driven by an inverter. The inverter circuit is also cooled by the air that is arranged and generated by the fan. In Patent Document 1, a control transistor for a switch of an electric tool is disposed on a heat sink, the heat sink is disposed near a battery, and an opening formed in a housing (lower handle portion) near the heat sink. Thus, a technology is disclosed in which outside air passes through a heat sink and a battery.

US Patent Application Publication No. 2003/0030984

  In a configuration using a brushless DC motor, the method of mounting all the switching elements on the rear surface of the circuit board is arranged so that the height direction of the switching elements is parallel to the rotation axis of the motor due to the mounting space. Is done. However, with such an arrangement, a space corresponding to the height of the circuit board and the switching element is required on the rear side in the axial direction of the motor. Therefore, when the motor is applied to an electric tool, the length of the housing in the front-rear direction is increased. turn into.

  On the other hand, in order to prevent the length of the housing in the front-rear direction from being increased, it is conceivable that the circuit board is provided inside the handle portion of the housing instead of the rear side of the motor as in Patent Document 1. However, in the configuration in which an opening is provided in the housing as in Patent Document 1 and the heat sink and the battery unit are merely radiated naturally, a large current is generated regardless of the arrangement of only the switching element that controls ON / OFF of the motor. It is insufficient to cool the switching element for the flowing brushless DC motor.

  The present invention has been made in view of the above-described background, and an object of the present invention is to generate an air flow for cooling a control electric circuit disposed at a location away from the motor by using an existing motor cooling fan. It is to provide a power tool.

  Another object of the present invention is to provide an electric tool that realizes a good cooling structure while mounting a switching element of a brushless DC motor at a position away from the motor.

  Still another object of the present invention is to provide an electric tool that actively cools a protection circuit for a brushed DC motor.

  Of the inventions disclosed in the present application, typical features will be described as follows.

According to one feature of the present invention, a motor having a rotary shaft extending in the front-rear direction, a switching element for controlling the motor, a power tool having a housing that accommodates these, the housing houses a motor And a battery holding part extending in the front-rear direction from the front end of the handle part, a board having a control circuit for controlling the switching element, and an air port around the board. The air introduced from the air port into the housing passes through the periphery of the substrate, the switching element and the motor, and is discharged from the housing by the fan . You may make it the air flow in a handle | steering-wheel part flow in the direction from the air opening to the suction side of a fan. The air port is preferably provided on the rear side surface of the housing.

  According to another feature of the invention, the motor is a brushless DC motor and the control circuit includes an inverter circuit for driving the brushless DC motor. The switching element of the inverter circuit that generates a large amount of heat is cooled by the airflow flowing through the handle portion. The motor is a brushed DC motor, and its control circuit includes an output transistor for protecting the motor, and the output transistor generating a large amount of heat is cooled by an air flow from a fan. In order to enhance the cooling effect, a rectifying plate for rectifying the air flow may be provided in the handle portion. In addition, a guide path for allowing an air flow to pass may be formed around a part of the substrate or around the substrate. Furthermore, a heat insulating material may be provided on the inner wall or the outer wall of the handle portion of the housing. Furthermore, you may make it provide the filter which filters air in the air intake port of a housing.

According to the present invention, the control circuit for controlling the rotation of the motor, disposed on a substrate provided in the handle portion or the battery retaining portion, provided air port in the handle portion or the battery retaining portion, utilizing a fan Since the control circuit is cooled by generating an air flow in the handle portion, even if a switching element that generates a large amount of heat is arranged in a narrow space in the handle portion, it can be effectively cooled. Further, since it is not necessary to separately provide an electric fan for cooling a control circuit provided at a location different from the motor, an effective cooling structure can be realized at low cost.

According to the invention of claim 2 , since the air flow in the handle portion flows in a direction from the air port to the fan suction side, the flow direction of the air flow in the handle portion can be kept constant and effective. A cooling structure can be realized.

  According to the invention of claim 3, since the motor is a brushless DC motor and the control circuit is an inverter circuit for driving the brushless DC motor, there is no need to install an inverter circuit on the rear side of the motor of the housing body, Since the space required on the rear side of the conventional motor can be omitted, it is possible to realize an electric tool having a compact front and rear length of the body portion.

  According to the invention of claim 4, the motor is a brushed DC motor, and the control circuit has an output transistor for protection of the brushed DC motor. A cooling structure for the output transistor in the brushed DC motor is provided. Since it can be added, reliable operation of the power tool can be guaranteed.

  According to the invention of claim 5, since the rectifying plate for rectifying the air flow is provided in the handle portion of the housing, the flow of the air flow in the housing can be made smooth and the cooling efficiency can be improved. it can.

  According to the invention of claim 6, since the guide path for allowing the air flow to pass is formed around the substrate or the substrate, the electronic elements mounted on the substrate can be effectively cooled.

  According to the seventh aspect of the present invention, since the heat insulating material is provided on the inner wall or the outer wall of the handle portion of the housing, it is possible to reduce the heat generated from the switching element in the handle portion from being transmitted to the hand of the operator holding the handle portion. The worker can work comfortably.

According to the eighth aspect of the present invention, since the air port is provided on the rear side surface of the housing, the exhaust discharged from the inside of the housing does not hit the worker, and the worker can work comfortably. In addition, even in an environment where dust is generated, such as in a cutting operation, it becomes difficult for dust to enter from the air opening .

According to invention of Claim 9, since the filter which filters air was provided in the air intake port, it can prevent effectively that dust enters into the inside of a housing .

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following description, the vertical and forward / backward directions will be described as the directions shown in FIG. FIG. 1 is a view showing an internal structure of an impact driver 1 as an embodiment of an electric power tool according to the present invention. The impact driver 1 uses a rechargeable battery 2 as a power source, drives a rotary impact mechanism 4 using a motor 3 as a drive source, and applies rotation and impact to an anvil 5 that is an output shaft, thereby providing a tip tool (not shown) such as a driver bit. Rotating impact force is intermittently transmitted to the screw to perform operations such as screw tightening and bolt tightening.

  The motor 3 is a brushless DC motor, and is accommodated in a cylindrical body portion 6a of a housing 6 having a substantially T shape in a side view. The rotating shaft 19 of the motor 3 is rotatably held by a bearing 17a on the rear end side of the body portion 6a and a bearing 17b provided near the center. Behind the motor 3 is disposed a substrate 7 on which a position detection element 42 is mounted for connection to the drive coil of the motor 3 and for detecting the rotational position of the rotor 3b.

  A trigger switch 8 and a forward / reverse switching lever 51 are disposed in an upper portion of a handle portion 6b extending integrally at a substantially right angle from the body portion 6a of the housing 6, and the handle portion is urged by a spring (not shown) to the trigger switch 8. A trigger operation portion 8c protruding from 6b is provided. A control circuit board 9 having a function of controlling the speed of the motor 3 by a pulling operation of the trigger operation portion 8c is accommodated below the handle portion 6b. Six more switching elements 21 are mounted on the control circuit board 9, and the motor 3 is rotated by performing inverter control with these switching elements 21. A battery 2 such as nickel metal hydride or lithium ion is detachably attached to the battery holding portion 6c below the handle portion 6b.

  A fan 18 attached to the rotary shaft 19 and rotating in synchronization with the motor 3 is provided in front of the motor 3. Air is sucked by the fan 18 from the air intake port 53 behind the body portion 6a as indicated by an arrow extending from the rear to the front, and is formed in the body portion 6a of the housing 6 and in the vicinity of the outer peripheral side in the radial direction of the fan 18. Air is discharged to the outside of the housing 6 by a plurality of slits (not shown). Further, as the fan 18 rotates, outside air is sucked in the direction of the arrow 30a from the air inlet / outlet 25 formed in the battery holding portion 6c of the housing 6, and then flows through the path of the arrow 30b and flows in the vicinity of the control circuit board 9. Thus, the switching element 21 such as a power FET mounted on the control circuit board 9 is cooled. The switching element 21 often has a heat sink on the back surface, but another heat sink made of aluminum may be attached to the heat sink so that the air flow 30b positively hits the heat sink.

  An air guide plate 22 is formed inside the handle portion 6b of the housing 6. The air guide plate 22 has a lower guide wall 22c that has a large opening on the lower side and narrows the flow path, and a flow path with a constant width near the center. The central wall 22b that forms the upper side and the upper guide wall 22a that guides the air flow in a predetermined direction on the upper side. The air that has cooled the mounted elements on the control circuit board 9 follows the paths of the arrows 30c, 30d, 30e, and 30f, and merges with the air sucked from the air intake port 53. For this reason, a hole or opening for ventilation is formed in the wall separating the handle portion 6b and the body portion 6a. In FIG. 1, the air intake 53 is formed in the body portion 6 a of the housing 6, but in addition to this, a plurality of slits may be formed in the housing 6 in the region around the substrate 7. good. The shape and arrangement position of the suction holes and slits formed in the housing 6 may be set so that an air flow sucked from the air inlet / outlet 25 formed in the battery holding portion 6c of the housing 6 is effectively generated. .

  Here, the air inlet / outlet port 25 is disposed on the rear side of the impact driver 1. This is to prevent dust from entering the inside as much as possible because the front side of the impact driver 1 is mostly dusty compared to the rear side, such as generation of cutting waste. Note that the air inlet / outlet 25 may be a simple hole, but a net or a filter may be attached in order to prevent entry of dust and dirt.

  The rotary striking mechanism 4 includes a planetary gear speed reduction mechanism 10, a spindle 11, and a hammer 12. When the trigger operation portion 8c of the trigger switch 8 is pulled and the motor 3 is activated, the rotation of the motor 3 is caused by the planetary gear speed reduction mechanism 10. And is transmitted to the spindle 11, and the spindle 11 is rotationally driven at a predetermined speed. Here, the spindle 11 and the hammer 12 are connected by a cam mechanism, and this cam mechanism is formed on the V-shaped spindle cam groove 11 a formed on the outer peripheral surface of the spindle 11 and on the inner peripheral surface of the hammer 12. The hammer cam groove 12a and the balls 13 engaged with the cam grooves 11a and 12a are configured.

  The hammer 12 is always urged forward by a spring 14, and when stationary, the hammer 13 is in a position spaced from the end face of the anvil 5 by the engagement of the ball 13 and the cam grooves 11a and 12a. And the convex part which is not illustrated is symmetrically formed in two places on the rotation plane which the hammer 12 and the anvil 5 mutually oppose.

  When the spindle 11 is driven to rotate, the rotation is transmitted to the hammer 12 via the cam mechanism, and the convex portion of the hammer 12 engages with the convex portion of the anvil 5 before the hammer 12 rotates halfway. When the relative reaction occurs between the spindle 11 and the hammer 12 due to the reaction force at that time, the hammer 12 compresses the spring 14 along the spindle cam groove 11a of the cam mechanism and moves toward the motor 3 side. And start retreating.

  When the protrusion of the hammer 12 moves over the protrusion of the anvil 5 by the backward movement of the hammer 12 and the engagement between the two is released, the hammer 12 is accumulated in the spring 14 in addition to the rotational force of the spindle 11. While being accelerated rapidly in the rotational direction and forward by the action of the elastic energy and the cam mechanism, the spring 14 is moved forward by the urging force of the spring 14, and the convex portion is reengaged with the convex portion of the anvil 5 to rotate integrally. start. At this time, since a strong rotational impact force is applied to the anvil 5, the rotational impact force is transmitted to the screw via a tip tool (not shown) attached to the anvil 5. Thereafter, the same operation is repeated, and the rotational impact force is intermittently repeatedly transmitted from the tip tool to the screw. For example, the screw is screwed into a material to be fastened such as wood.

  FIG. 2 is a top view of the control circuit board 9 shown in FIG. 1 as viewed from above. In FIG. 2, not only the control circuit board 9 but also the surrounding housing 6 portion is shown. The control circuit board 9 is disposed on the partition wall 6d between the handle portion 6b of the housing 6 and the battery holding portion 6c or so as to be sandwiched between the partition walls 6d. The partition wall 6d is formed with a through hole 6e through which the power line is passed. Six switching elements 21 are mounted on the control circuit board 9 in a vertical direction with respect to the control circuit board 9, that is, the height direction of the switching elements 21 is arranged vertically. Since the mounting efficiency on the substrate is improved by arranging the switching element 21 in this way, it is suitable when the switching element 21 is arranged in the handle portion 6b whose diameter is limited. is there.

  The control circuit board 9 has a shape conforming to the upper surface shape of the battery 2. A control panel 27 exposed on the upper surface of the battery holding portion 6 c is attached to the front side of the upper surface, and an air inlet / outlet is provided on the side. A notch 24 is formed that defines a guide path for allowing the air introduced from 25 to flow from the lower side to the upper side of the control circuit board 9. It should be noted that the number of guide paths formed on the control circuit board 9 is arbitrary as the place where the air guide path is formed, and may be set according to the mounted elements to be cooled.

  Various operation buttons and display lamps are mounted on the control panel 27. The light button 36 is a light touch switch, and the white LED light attached to the impact driver 1 can be turned on / off by pressing this button. The battery remaining amount button 37 is a light touch switch. When this button is pressed, the battery remaining amount display lamp 38 indicating the battery mark indicates that the remaining amount of the battery is “full charge (two LEDs are lit)” “approximately half (one LED is present). It is possible to check which of the three levels of “lighting” and “low remaining amount (both two LEDs do not light)”. The strength display lamp 39 is a lamp that indicates the strength of the tightening torque set by the strength switching switch 35a, and in which of the four stages (for example, 2600, 2000, 1200, 500 times / minute) the number of rotations of the motor 3 is. Whether it is set or not is indicated by the number of LED lighting. The single / repetitive display lamp 40 displays whether the single / repetitive mode is switched each time the single / repetitive changeover switch 35b is pressed. The single shot mode is a mode in which the trigger operation unit 8c is pulled to start hitting and then automatically stopped by several hits (1 to 4 times). In the continuous mode, when the trigger operation unit 8c is pulled to start hitting, continuous hitting is performed. This is a mode that does not stop automatically.

  As shown in FIG. 4, connectors 53 and 54 are provided on the rear side of the control circuit board 9, and a switching element driving signal from a control signal output circuit described later is input through the connector 54. The control circuit board 9 is connected to the trigger switch 8 via the connector 53.

  Next, the configuration and operation of the drive control system of the motor 3 will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the motor drive control system. In the present embodiment, the motor 3 is a three-phase brushless DC motor. This brushless DC motor is a so-called inner rotor type, and includes a rotor (rotor) 3b including a plurality of sets (two sets in this embodiment) of permanent magnets (magnets) including N poles and S poles. In order to detect the rotational position of the stator 3a composed of three-phase stator windings U, V, and W connected in a star connection, and the rotational position of the rotor 3b, they are arranged at predetermined intervals in the circumferential direction, for example, at an angle of 60 °. The three rotational position detecting elements (Hall elements) 42 are provided. Based on the position detection signals from these rotational position detection elements 42, the energization direction and time to the stator windings U, V, W are controlled, and the motor 3 rotates. The rotational position detecting element 42 is provided at a position facing the magnet of the rotor 3 b on the substrate 7.

  The electronic elements mounted on the control circuit board 9 include six switching elements Q1 to Q6 such as FETs (Field Effect Transistors) connected in a three-phase bridge format. The gates of the six switching elements Q1 to Q6 connected in a bridge are connected to a control signal output circuit 46 mounted on the control circuit board 9, and the drains or sources of the six switching elements Q1 to Q6 are It is connected to the stator windings U, V, W that are star-connected. As a result, the six switching elements Q1 to Q6 perform a switching operation by the switching element drive signals (drive signals such as H4, H5, and H6) input from the control signal output circuit 46, and are applied to the inverter circuit 47. Electric power is supplied to the stator windings U, V, and W using the DC voltage of the battery 2 as three-phase (U-phase, V-phase, and W-phase) voltages Vu, Vv, and Vw.

  Of the switching element drive signals (three-phase signals) for driving the gates of the six switching elements Q1 to Q6, the three negative power supply side switching elements Q4, Q5, Q6 are converted into pulse width modulation signals (PWM signals) H4, The pulse width (duty ratio) of the PWM signal is supplied as H5 and H6 and based on the detection signal of the operation amount (stroke) of the trigger operation unit 8a of the trigger switch 8 by the arithmetic unit 41 mounted on the control circuit board 9. The amount of electric power supplied to the motor 3 is adjusted by changing, and the start / stop of the motor 3 and the rotation speed are controlled.

  Here, the PWM signal is supplied to any one of the positive power supply side switching elements Q1 to Q3 or the negative power supply side switching elements Q4 to Q6 of the inverter circuit 47, and the switching elements Q1 to Q3 or the switching elements Q4 to Q6 are switched at high speed. As a result, the power supplied to the stator windings U, V, W from the DC voltage of the battery 2 is controlled. In this embodiment, since the PWM signal is supplied to the negative power supply side switching elements Q4 to Q6, the electric power supplied to each stator winding U, V, W is controlled by controlling the pulse width of the PWM signal. The rotational speed of the motor 3 can be controlled by adjusting.

  The impact driver 1 is provided with a forward / reverse switching lever 51 for switching the rotational direction of the motor 3, and the rotational direction setting circuit 50 switches the rotational direction of the motor each time a change in the forward / reverse switching lever 51 is detected. The control signal is transmitted to the calculation unit 41. Although not shown, the calculation unit 41 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 and control data, and for temporarily storing data. RAM, a timer, and the like.

  The control signal output circuit 46 forms a drive signal for alternately switching predetermined switching elements Q1 to Q6 based on the output signals of the rotation direction setting circuit 50 and the rotor position detection circuit 43, and controls the drive signal. The signal is output to the signal output circuit 46. As a result, the predetermined windings of the stator windings U, V, and W are alternately energized to rotate the rotor 3b in the set rotation direction. In this case, the drive signal applied to the negative power supply side switching elements Q4 to Q6 of the substrate 7 is output as a PWM modulation signal based on the output control signal of the applied voltage setting circuit 49. The current value supplied to the motor 3 is measured by the current detection circuit 48, and the value is fed back to the calculation unit 41 so as to be adjusted to the set driving power. The PWM signal may be applied to the positive power supply side switching elements Q1 to Q3.

  Next, a second embodiment of the present invention will be described with reference to FIG. Since the basic configuration as an impact driver is the same as that of the embodiment of FIG. 1, the reference numerals of the same portions that are not mentioned redundantly are omitted (the same applies to the following drawings). In the second embodiment, the airflow flowing in the handle portion 6b of the housing 6 is in the opposite direction to the embodiment shown in FIG. In the handle portion 6 b, air flows 31 a, 31 b, 31 c that flow downward are generated by the fan 18. This is because a through hole 26 is provided in a wall separating the body portion 6a and the handle portion 6b of the housing 6, and a part of the air generated by the fan 18 and normally discharged outside the housing 6 is guided to the handle portion 6b. Is achieved. The airflow that has passed through the through hole 26 flows as indicated by arrows 31b and 31c, and is guided to hit the switching element 21a mounted on the control circuit board 9. In FIG. 4, the air guide plate 22 shown in FIG. 1 is not provided, but it may be provided. Unlike the embodiment of FIG. 1, the switching element 21 a is attached so as to be located at a distance from the control circuit board 9. This can be realized by soldering to the control circuit board 9 with the legs (lead wires) of the switching elements 21a such as FETs left long. If fixed in this manner, the surface area of the switching element 21a exposed to the air flow is increased, so that the cooling can be effectively performed.

  The air flow that has cooled the switching element 21 a passes through the notch 24 of the control circuit board 9, flows as indicated by arrows 31 d and 31 e, and is discharged from the air inlet / outlet 25 to the outside of the housing 6. In the second embodiment, since the air flowing in the handle portion 6b uses the exhaust of the fan 18, the flow rate of the air flowing in the handle portion 6b is adjusted by adjusting the size and shape of the through hole 26. There is an advantage that it is relatively easy to adjust. However, in the embodiment of FIG. 1, the air for cooling the switching element 21 is air introduced from the outside air, whereas the second embodiment is the air after cooling the motor 3 and is higher than the outside air temperature. Therefore, the cooling efficiency is inferior at the same flow rate. Therefore, it is preferable to determine which embodiment is preferable in consideration of whether the cooling of the motor 3 is important or the cooling of the switching elements 21 and 21a is important.

  Next, a third embodiment of the present invention will be described with reference to FIG. The direction and the generation principle of the air flow flowing through the handle portion 6b according to the third embodiment are the same as those of the second embodiment (FIG. 4), and a part of the air discharged by the fan 18 is passed through the through hole 26. To the handle portion 6b, flows as indicated by arrows 32a, 32b, 32c, 32d, and 32e, and is discharged from the air inlet / outlet 25 to the outside of the housing 6. In FIG. 5, the heat insulating material 23 is arranged on the inner peripheral side of the handle portion 6 b so that the handle portion 6 b gripped by the operator is not heated. Various materials can be considered for the heat insulating material 23, but it is preferable that the inner peripheral side is a smooth material so as not to obstruct the flow of the air flow indicated by the arrows 32b and 32c. Further, the heat insulating material may be disposed on the inner wall side of the handle portion 6b or on the outer wall side.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is different from the first embodiment (FIG. 1) in that it does not have the air guide plate 22 and that the outside air sucked from the air inlet / outlet 25 has arrows 33a, 33b, 33c, and 33d. Via, as shown by the arrow 33e, it flows through the through hole 26a and in the vicinity of the rear entrance of the fan 18. In this configuration, the air flow taken in from the air inlet / outlet 25 and warmed by the switching element 21 is not introduced into the motor 3, so that cooling of the motor 3 is not hindered. Moreover, since the air taken in from the air inlet / outlet 25 directly hits the switching element 21, the effective cooling characteristic can be maintained. Although the air guide plate 22 is not provided in the fourth embodiment, it may be provided in the same manner. Moreover, you may arrange | position the heat insulating material 23 to the inner peripheral side of the handle | steering-wheel part 6b like 3rd Embodiment.

  As a modification of the fourth embodiment, a filter 28 may be attached to the air inlet / outlet port 25 as shown in FIG. The filter 28 is in the form of an adhesive tape made of a porous film, for example, and is attached from the outside of the housing 6. The porous membrane desirably has fine pores having a size of about 0.1 to 10 micrometers in order to pass a gas such as air or water vapor and to play a liquid such as water or a solid such as dust. As the porous film, for example, a tetrafluoroethylene resin porous film or a film made of expanded polytetrafluoroethylene (ePTFE) can be used.

  The size of the micropores of the porous membrane may be 0.001 to 0.1 micrometers. With such a fine pore size, the waterproof property is further improved, and it is possible to more reliably prevent the intrusion of water droplets and dust. Further, the micropore size of the porous membrane may be 10 micrometers to 1000 micrometers. With such a fine pore size, air permeability is further improved. For this reason, the inflow of air into the outer frame becomes easier. Therefore, the resistance when air flows into the housing is reduced, and the efficiency of the fan 18 can be increased.

  As an example of attaching the filter 28, the present specification has been described as a modification of the fourth embodiment. However, the filter 28 can be combined with all other embodiments. In FIG. 7, the filter 28 is attached to the outside of the housing 6 as an adhesive tape, but the filter 28 may be attached to the inside without being limited to the outside. Further, the filter 28 is not only in the form of an adhesive tape, but a filter case for accommodating the filter 28 is attached to the housing 6 or the housing 6 is processed so that the filter 28 is accommodated in the processed portion. good.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. The fifth embodiment differs from the first embodiment (FIG. 1) in that the motor that rotates the impact driver 61 is a direct current motor 63 having a brush. This is the same as the rotary striking configuration 4 of the first embodiment. The DC motor 63 includes a stator 63a using a permanent magnet and a rotor 63b to which current is supplied via a brush. On the front side of the DC motor 63, a cooling fan 68 for the DC motor 63 is provided coaxially with the rotating shaft of the DC motor 63. The air flow generated by the fan 68 is sucked from an air intake 67 or a slit 71 provided in the body portion 66a of the housing. In addition, the air drawn in from the air inlet / outlet 65 provided in the battery holding portion 66c of the housing flows from the arrows 73a to 73b to cool the mounted elements on the control board 69, and then the handle of the housing. It flows through the inside of the part 66b and flows into the rear part of the DC motor 63 via arrows 73c, 73d, 73e, 73f.

  An air guide plate 72 is provided inside the handle portion 66b, and the air guide plate 72 extends downward and a lower guide wall 72c for slightly restricting the flow path, and a central wall 72b for greatly reducing the flow path near the center, It is constituted by an upper guide wall 72a that maintains a narrow flow path state on the upper side. A control panel 70 is provided on the upper front side of the control circuit 69.

  As described above, according to the present invention, using the fan attached to the rotating shaft of the motor, the inside of the handle portion of the housing is moved from the body portion toward the battery side (from the top to the bottom) or from the battery side. Since air flows in the direction of the body part (from bottom to top), the control circuit board and the electronic element provided in the handle part or the battery holding part can be effectively cooled.

  Moreover, since the switching element 21 is not disposed on the rear end side of the motor but is disposed on the handle portion of the housing or the battery holding portion, the power tool that can be configured compactly by shortening the front and rear length of the body portion of the housing. realizable. Furthermore, since an electronic element generating a large amount of heat can be mounted in the handle portion of the housing, the power tool can be downsized and the degree of design freedom can be increased.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning. For example, in the present embodiment, the form applied to the impact driver as an example of the electric power tool has been described. However, the present invention is not limited to the impact driver, and can be similarly applied to any electric power tool that uses an electric motor as a drive source. It is.

It is a figure which shows the internal structure of the impact driver which concerns on the 1st Embodiment of this invention. It is the top view which looked at the control circuit board 9 shown in FIG. 1 from the top. It is a block diagram which shows the structure of the drive control system of the motor 3 of FIG. It is a figure which shows the internal structure of the impact driver which concerns on the 2nd Embodiment of this invention. It is a figure which shows the internal structure of the impact driver which concerns on the 3rd Embodiment of this invention. It is a figure which shows the internal structure of the impact driver which concerns on the 4th Embodiment of this invention. It is sectional drawing which concerns on the modification of the 4th Embodiment of this invention, and shows the state which attached the filter 28 to the air inlet / outlet 25. It is a figure which shows the internal structure of the impact driver which concerns on the 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a-1c Impact driver 2 Battery 3 Motor 3a Motor stator 3b Motor rotor 4 Rotating impact mechanism 5 Anvil 6 Housing 6a (Housing) Body part 6b (Housing) Handle part 6c (Housing) Battery holding Part 6d (housing) partition 6e Through hole 7 Substrate 8 Trigger switch 8a Trigger operation part 9 Control circuit board 10 Planetary gear speed reduction mechanism 11 Spindle 11a Spindle cam groove 12 Hammer 12a Hammer cam groove 13 Ball 14 Spring 15 Sleeve 16a Ball bearing 16b Metal bearing
17a, 17b Bearing 18 Fan 19 (Motor) Rotating shaft 21, 21a Switching element
22 air guide plate 22a upper guide wall 22b central wall 22c lower guide wall 23 heat insulating material 24 notch 25 air inlet / outlet 26, 26a through hole 27 control panel 28 filter 35a strength change switch 35b single / repetitive change switch 36 light button 37 battery remaining Volume button 38 Battery level indicator lamp 39 Strength indicator lamp
40 Single / Sequential Display Lamp 41 Arithmetic Unit 42 Rotation Position Detection Element 43 Rotor Position Detection Circuit 44 Fan Rotation Control Unit 46 Control Signal Output Circuit 47 Inverter Circuit 48 Current Detection Circuit 49 Applied Voltage Setting Circuit 50 Rotation Direction Setting Circuit 51 Forward / Reverse Switching lever 53, 54 Connector 61 Impact driver 62 Battery 63 DC motor 63a Motor stator 63b Motor rotor 64 Rotary impact mechanism 66a (housing) body 66b (housing) handle 66c (housing) battery holding part 69 control circuit board 70 control panel 71 slit 72 air guide plate 72a upper guide wall 72b central wall 72c lower guide wall

Claims (9)

A motor having a rotation shaft extending in the front-rear direction, a fan attached to the rotation shaft of the motor for cooling the motor, a switching element for controlling the motor, and a housing for housing these,
The housing has a body part for housing the motor, and a handle part extending from the body part,
A board having a control circuit for controlling the switching element in a battery holding part extending in the front-rear direction from the front end of the handle part, an air port around the board, and air introduced into the housing from the air port Is a power tool that passes through the periphery of the substrate, the switching element, and the motor, and is discharged out of the housing by the fan.   The power tool according to claim 1, wherein an air flow in the handle portion flows in a direction from the air port to a suction side of the fan.   The electric tool according to claim 2, wherein the motor is a brushless DC motor, and the control circuit includes an inverter circuit that drives the brushless DC motor.   3. The electric tool according to claim 2, wherein the motor is a brushed DC motor, and the control circuit includes an output transistor for protecting the brushed DC motor.   The power tool according to any one of claims 1 to 4, wherein a rectifying plate for rectifying the airflow is provided in the handle portion of the housing.   The power tool according to any one of claims 1 to 5, wherein a guide path for allowing the air flow to pass therethrough is formed around the substrate or the substrate.   The power tool according to claim 1, wherein a heat insulating material is provided on an inner wall or an outer wall of the handle portion of the housing.   The power tool according to claim 1, wherein the air port is provided on a rear side surface of the housing. The power tool according to claim 1, wherein a filter for filtering air is provided in the air port.

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