JP2009196013A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool enabling an increase in production efficiency and a reduction in maintenance cost by protecting a connector section by an elastic body in place of silicone coating. <P>SOLUTION: This impact driver (power tool) 1 is formed by storing at least a brushless motor 3, an inverter circuit board 5, and a control board 11 in a housing 6, inserting a flat cable 12 extending from the control board 11 into the connector 13 of the inverter circuit board 5, and connecting the control board 11 and the inverter circuit board 5 to each other. The elastic body 23 is interposed between the inverter circuit board 5 in the housing 6 and the inner wall of the housing 6. The connector 13 section of the inverter circuit board 5 is stored in an enclosed space S demarcated by the elastic body 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric tool that operates using a brushless motor as a drive source.

  An inverter circuit board (motor drive circuit board) is indispensable for a power tool that operates using a brushless motor as a drive source. However, the electrical connection between the inverter circuit board and the control board is a flat that can be compactly mounted. Flat cables are used exclusively.

  FIG. 10 shows an impact driver as an example of such an electric tool.

  FIG. 10 is a side sectional view of a conventional impact driver. The illustrated impact driver 101 drives a rotary impact mechanism using a battery 102 as a power source and a brushless motor 103 as a drive source, and applies rotation and impact to the anvil 104. Thus, the rotary impact force is intermittently transmitted to a bit (not shown), which is a tip tool, to perform operations such as screw tightening.

  The brushless motor 103, the rotary hitting mechanism, the planetary gear mechanism 115, the inverter circuit board 105, the control board 111, the switch board 108, and the like are accommodated in the housing 106. The rotary hitting mechanism includes a spindle 116, a hammer 120, and an anvil 104. , A cam mechanism, a ball 121, a spring 122, and the like.

  Incidentally, a flat flat cable 112 is used for the connection between the inverter circuit board 105 and the control board 111, and an end of the flat cable 112 extending from the control board 111 is inserted into the connector 113 of the inverter circuit board 105. Connected.

Thus, when the switch trigger 107 is turned on, the switch board 108 operates to supply power from the battery 102 to the brushless motor 103 to start the brushless motor 103, and the inverter circuit board 105 is controlled by a control signal from the control board 111. The brushless motor 103 is controlled, and the rotation of the brushless motor 103 is decelerated by the planetary gear mechanism 115 and transmitted to the spindle 116, and the spindle 116 is driven to rotate. Then, the rotation of the spindle 116 is converted into a rotational striking force by a rotary striking mechanism and transmitted to a bit (not shown) through the anvil 104, and a screw (not shown) is screwed into a fastened material such as wood.
JP 2006-289545 A

  By the way, in the impact driver 101 shown in FIG. 10, if water or dust enters the connector 113 portion that is a connection portion of the flat cable 111 to the inverter circuit board 105, a short circuit failure may occur. The connection part was protected by applying silicon 130 to the part.

  However, when silicon 130 is applied to the connector 113 portion, assembly cannot be performed unless the silicon 130 is solidified, and it takes a long time of 12 hours or more to solidify. There was a problem of being bad. Further, since it is necessary to leave the inverter circuit board 105 and the like until the silicon 130 is hardened, there is a problem that a large space is required.

  Furthermore, once the silicon 130 is applied, the inverter circuit board 105 and the control board 111 cannot be integrated and separated from each other. Therefore, even if only one of the inverter circuit board 105 and the control board 111 fails. There is a problem in that both the boards 105 and 111 need to be replaced at the same time, which increases the maintenance cost.

  The present invention has been made in view of the above-mentioned problems, and the object of the process is to protect the connector portion with an elastic body instead of silicon coating, thereby improving production efficiency and reducing maintenance costs. It is to provide a power tool.

  In order to achieve the above object, according to a first aspect of the present invention, at least a brushless motor, an inverter circuit board and a control board are accommodated in a housing, and a cable extending from the control board is inserted into a connector of the inverter circuit board for control. In the electric tool formed by connecting the board and the inverter circuit board, an elastic body A is interposed between the inverter circuit board and the housing inner wall in the housing, and a sealed space defined by the elastic body A is provided. The connector part of the inverter circuit board is accommodated.

  According to a second aspect of the present invention, in the first aspect of the invention, a slit-like fitting groove is formed in the elastic body A, and the fitting groove is fitted into a rib on which the housing is formed. , And the elastic body A is pressed against the inverter circuit board to be brought into close contact therewith.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein another elastic body B is interposed between at least a part of the outer periphery of the inverter circuit board and the inner wall of the housing, and the elastic body B The cable is sandwiched between the inner wall of the housing.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, a fitting groove is formed along the inner circumference of the elastic body B, and the fitting groove is fitted into a part of the outer circumference of the inverter circuit board. The elastic body B is fixed and the elastic body B is pressed and brought into close contact with the inner wall of the housing.

  According to the configuration of the first aspect, since the connector portion of the inverter circuit board is accommodated in the sealed space defined by the elastic body A interposed between the inverter circuit board in the housing and the inner wall of the housing, Water and dust do not invade, preventing short circuit failures. In this way, the connector portion is sealed with an elastic body instead of the conventional silicon coating to prevent water and dust from entering the connector portion, so that the productivity is improved and the inverter circuit board connected by the cable When one of the control boards fails, only the failed board needs to be replaced, so that the maintenance cost can be kept low.

  According to the second aspect of the present invention, the elastic body A can be easily fixed by fitting the fitting groove formed in the elastic body A into the rib formed in the housing. By pressing and intimately contacting the inverter circuit board, the connector part of the inverter circuit board can be reliably sealed to reliably prevent water and dust from entering the connector part.

  According to the third aspect of the present invention, the cable is held between the inner wall of the housing by the elastic body B interposed between a part of the outer periphery of the inverter circuit board and the inner wall of the housing. A load does not act on the connection portion to the circuit board, and the cable is not tilted to cause a short circuit failure or disconnection of the cable. In addition, since the inverter circuit board is elastically supported by the elastic body B, the impact applied to the inverter circuit board by the overturning or dropping of the power tool is absorbed and alleviated by the elastic body B, and the inverter circuit board is protected and damaged. It is prevented.

  According to the fourth aspect of the present invention, the elastic body B can be easily fixed by fitting the fitting groove formed along the inner periphery of the elastic body B into a part of the outer periphery of the inverter circuit board. it can. The cable can be securely held between the inner wall of the housing by pressing the elastic body B against the inner wall of the housing and bringing it into close contact therewith.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side sectional view of an impact driver as an embodiment of an electric power tool according to the present invention, FIG. 2 is an enlarged detail view of part A in FIG. 1, FIG. 3 is a perspective view of an elastic body, and FIG. FIG. 5, FIG. 5 is a sectional view taken along line BB of FIG. 4, FIG. 6 is a side view of the brushless motor, FIG. 7 is a rear view of the brushless motor (a view in the direction of arrow C in FIG. 6), and FIG. FIG. 9 is a sectional view taken along the line DD of FIG.

  FIG. 1 is a side sectional view of an impact driver. The impact driver 1 shown in FIG. 1 has a battery 2 as a power source, a brushless motor 3 as a drive source, drives a rotary impact mechanism, and rotates and strikes the anvil 4. A rotating impact force is intermittently transmitted to a bit (not shown), which is a tool, to perform operations such as screw tightening.

  The brushless motor 3 and an inverter circuit board 5 for driving and controlling the brushless motor 3 are accommodated in a body portion 6A of the housing 6 and are disposed above the handle portion 6B integrally extending downward from the body portion 6A of the housing 6. The switch trigger 7 for starting / stopping the brushless motor 3 by turning on / off the power supply from the battery 2 to the brushless motor 3 and the forward / reverse for switching the forward rotation and the reverse rotation of the brushless motor 3. A switching lever 9 is provided. The inverter circuit board 5 is provided with four output transistors (FETs) 10 (see FIG. 7).

  A control board 11 is accommodated in the lower part (battery mounting part) of the handle 6B of the housing 6, and the flat cable 12 extending from the control board 11 passes through the handle 6B of the housing 6 to the body 6A. The end portion is inserted into the inverter circuit board 5 with the connector 13, and the control board 11 and the inverter circuit board 5 are electrically connected via the flat cable 12.

  On the other hand, in the rotary striking mechanism built in the hammer case 14, the rotation of the output shaft 3a of the brushless motor 3 is decelerated via the planetary gear mechanism 15 and transmitted to the spindle 16, and the spindle 16 is driven to rotate at a predetermined speed. Is done.

  One end (rear end) in the axial direction of the spindle 16 is rotatably supported by the gear cover 18 via a bearing 17, and the other end (front end) is rotatably held at the center of the anvil 4. The anvil 4 is rotatably supported on the front end portion of the hammer case 14 via a bearing metal 19.

  Further, a hammer 20 is rotatably supported on the outer periphery of the spindle 16, and the spindle 16 and the hammer 20 are connected by a cam mechanism. Here, the cam mechanism includes a V-shaped spindle cam groove 16a formed on the outer peripheral surface of the spindle 16, a V-shaped hammer cam groove 20a formed on the inner peripheral surface of the hammer 20, and the cam grooves 16, 20a. It is comprised with the ball | bowl 21 engaged with. The hammer 20 is always urged in the distal direction (rightward in FIG. 1) by a spring 22, and at rest, the ball 21 and the cam grooves 16a and 20a are engaged with each other so that a gap is provided between the hammer 20 and the end face of the anvil 4. In the position. In addition, the convex parts 20b and 4a are symmetrically formed in two places on the rotation plane where the hammer 20 and the anvil 4 face each other.

  Thus, when the switch trigger 7 is turned on, the switch board 8 is operated to supply power from the battery 2 to the brushless motor 3 to start the brushless motor 3, and the inverter circuit board 5 is controlled by a control signal from the control board 11. And the brushless motor 3 is controlled, the rotation of the brushless motor 3 is decelerated by the planetary gear mechanism 15 and transmitted to the spindle 16, and the spindle 16 is driven to rotate.

  When the spindle 16 is rotationally driven as described above, the rotation is transmitted to the hammer 20 via the cam mechanism, and the hammer 20 has a convex portion 20b that is projected to the convex portion of the anvil 4 before the hammer 20 rotates halfway. 4a is engaged to rotate the anvil 4, and when the relative reaction force is generated between the spindle 16 and the hammer 20 by the engagement reaction force at that time, the hammer 20 springs along the spindle cam groove 16a of the cam mechanism. Retracting toward the brushless motor 3 side is started while compressing 22.

  When the protrusion 20b of the hammer 20 passes over the protrusion 4a of the anvil 4 by the backward movement of the hammer 20 and the engagement between the two is released, the hammer 20 applies to the spring 22 in addition to the rotational force of the spindle 16. While being accelerated rapidly in the rotational direction and forward by the accumulated elastic energy and the action of the cam mechanism, it moves forward by the urging force of the spring 22, and its convex part 20 b is engaged with the convex part 4 a of the anvil 4 again. And start to rotate together. At this time, since a strong rotational impact force is applied to the anvil 4, the rotational impact force is transmitted to a screw (not shown) via a bit (not shown) attached to the anvil 4.

  Thereafter, the same operation is repeated so that the rotational impact force is intermittently repeatedly transmitted from the bit to the screw, and the screw is screwed into the material to be fastened such as wood.

  Next, the gist of the present invention will be described with reference to FIGS.

  As shown in detail in FIG. 2, an elastic body 23 is interposed between the inverter circuit board 5 in the housing 6 and the inner wall of the housing 6, and a sealed space in the housing 6 defined by the elastic body 23. The connector 13 of the inverter circuit board 5 is accommodated in S. Here, as shown in FIGS. 3 to 5, the elastic body 23 is integrally formed in a prismatic shape with rubber or the like, and a slit-like fitting groove 23 a is formed in the longitudinal direction (FIG. 3 and FIG. 3) at the center in the width direction. It is penetrated in the left-right direction of FIG.

  As shown in detail in FIG. 2, a rib 6 a is projected horizontally from the inner surface of the rear wall of the housing 6 toward the front (right side in FIG. 2), and the elastic body 23 is fitted on the rib 6 a. The elastic body 23 is fixed in a compressed state with the inverter circuit board 5 by fitting the mating groove 23a. Therefore, the elastic body 23 is pressed against the inverter circuit board 5 and is in close contact with the inverter circuit board 5 to hermetically seal the sealed space S.

  On the other hand, as shown in detail in FIG. 2, another elastic body 24 is interposed between the lower outer periphery of the inverter circuit board 5 and the inner wall of the housing 6, and the flat cable 12 is connected to the elastic body 24. It is sandwiched between the inner wall of the housing 6. Here, as shown in FIG. 8, the elastic body 24 is formed by integrally molding rubber or the like into a substantially U shape along the shape of the lower outer periphery of the inverter circuit board 5, and as shown in FIG. A fitting groove 24a is formed along the inner periphery thereof.

  Thus, as shown in FIGS. 6 and 7, the elastic body 24 is fixed to the inverter circuit board 5 by fitting the fitting groove 24 a into the lower outer periphery of the inverter circuit board 5. However, in the fixed state, it is compressed between the inverter circuit board 5 and the inner wall of the housing 6. Accordingly, the elastic body 24 is pressed and brought into close contact with the inner wall of the housing 6, and as shown in FIG. 2, the flat cable 12 is sandwiched between the inner wall of the housing 6 and securely fixed, and the sealed space S is formed. Seal hermetically.

  As described above, in the impact driver 1 according to the present embodiment, the sealed space defined by the elastic bodies 23 and 24 interposed between the inverter circuit board 5 in the housing 6 and the inner wall of the housing 6. Since the connector 13 portion of the inverter circuit board 5 is accommodated in S, water and dust do not enter the connector 13 and the occurrence of a short circuit failure or the like is prevented. As described above, the connector 13 is securely sealed by the elastic bodies 23 and 24 instead of the conventional silicon coating to prevent water and dust from entering the connector 13 so that the productivity is improved and the flatness is improved. When one of the inverter circuit board 5 and the control board 11 connected by the cable 12 fails, only the failed inverter circuit board 5 or the control board 11 needs to be replaced, so that the maintenance cost can be kept low.

  In this embodiment, the elastic body 23 can be easily fixed by fitting the fitting groove 23a formed in the elastic body 23 into the rib 6a formed in the housing 6, and the elastic body By pressing 23 closely against the inverter circuit board 5, the connector 13 portion of the inverter circuit board 5 can be reliably sealed and water and dust can be reliably prevented from entering the connector 13 portion.

  Further, in the impact driver 1 according to the present embodiment, the flat cable 12 is connected between the inner wall of the housing 6 by the elastic body 24 interposed between the lower outer periphery of the inverter circuit board 5 and the inner wall of the housing 6. As a result, the load is not applied to the connecting portion of the flat cable 12 to the inverter circuit board 5, and the flat cable 12 may be inclined to cause a short-circuit failure or the flat cable 12 to come off. Absent. Further, since the inverter circuit board 5 is elastically supported by the elastic body 24, the impact applied to the inverter circuit board 5 due to the fall or drop of the impact driver 1 is absorbed and relaxed by the elastic body 24, and the inverter circuit board 5 is protected. Damage is prevented.

  In the present embodiment, the elastic body 24 can be easily fixed by fitting the fitting groove 24 a formed along the inner periphery of the elastic body 24 into the lower outer periphery of the inverter circuit board 5. Further, the flat cable 12 can be securely clamped between the inner wall of the housing 6 by pressing the elastic body 24 against the inner wall of the housing 6 to be brought into close contact therewith.

  Although the present invention has been described with respect to an embodiment in which the present invention is applied to an impact driver, it is needless to say that the present invention can be similarly applied to any other electric tool using a brushless motor as a drive source. .

It is a sectional side view of the impact driver as one form of the electric tool concerning the present invention. It is the A section enlarged detail drawing of FIG. It is a perspective view of an elastic body. It is a top view of an elastic body. It is the BB sectional view taken on the line of FIG. It is a side view of a brushless motor. It is a rear view (figure of the arrow C direction of FIG. 6) of a brushless motor. It is a front view of an elastic body. It is the DD sectional view taken on the line of FIG. It is a sectional side view of the conventional impact driver.

Explanation of symbols

1 Impact driver (electric tool)
DESCRIPTION OF SYMBOLS 2 Battery 3 Brushless motor 2a Brushless motor output shaft 4 Anvil 4a Anvil convex part 5 Inverter circuit board 6 Housing 6A Housing body part 6B Housing handle part 7 Switch trigger 8 Switch board 9 Forward / reverse switching lever 10 Output transistor 11 Control Board 12 Flat cable 13 Connector of inverter circuit board 14 Hammer case 15 Planetary gear mechanism 16 Spindle 16a Spindle cam groove 17 Bearing 18 Gear cover 19 Bearing metal 20 Hammer 20a Hammer cam groove 20b Hammer convex part 21 Ball 22 Spring 23 Elastic body 23a Elastic body Fitting groove 24 elastic body 24a fitting groove S of elastic body S sealed space

Claims (4)

In an electric tool comprising at least a brushless motor, an inverter circuit board and a control board in a housing, and connecting the control board and the inverter circuit board by inserting a cable extending from the control board into a connector of the inverter circuit board.
An elastic body A is interposed between the inverter circuit board in the housing and the inner wall of the housing, and a connector portion of the inverter circuit board is housed in a sealed space defined by the elastic body A. tool.   A slit-like fitting groove is formed on the elastic body A, the fitting groove is fitted into a rib formed on the housing to fix the elastic body A, and the elastic body A is pressed against the inverter circuit board. The power tool according to claim 1, wherein the power tool is closely attached.   The elastic body B is interposed between at least a part of the outer periphery of the inverter circuit board and the inner wall of the housing, and the cable is sandwiched between the inner wall of the housing by the elastic body B. Item 3. The electric tool according to Item 1 or 2. A fitting groove is formed along the inner circumference of the elastic body B, the fitting groove is fitted into a part of the outer circumference of the inverter circuit board to fix the elastic body B, and the elastic body B is fixed to the housing. The power tool according to claim 3, wherein the power tool is pressed against and closely adhered to the inner wall.

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