JP5170624B2 - Flat cable protection structure - Google Patents

Description

  The present invention relates to a power tool that uses a brushless motor, and more particularly to a protective structure for a flat cable that connects substrates of impact drivers.

  An electric power tool such as an impact driver has a motor that is a drive source, a speed reduction mechanism that decelerates the rotation of the motor, and a motor that converts the rotation of the motor decelerated by the speed reduction mechanism into a rotational impact force and transmits it to the tip tool. It is configured to include a mechanism part and the like, and the rotational speed of the motor can be varied according to the stroke of the trigger.

  For impact drivers, etc., the maximum rotation of the motor is controlled by regulating the maximum stroke of the trigger according to the size of the screw, the material of the material to be tightened, the finish level, etc. A switching lever is provided to keep the speed (output) below a certain value.

  Further, in the impact driver equipped with the brushless motor, flat cables 39A and 39B (see FIG. 5) which can mount wiring on the mounted board relatively compactly are used. 5A and 5B are front views of the flat cable.

JP 2006-297532 A

  At the time of assembling an impact driver equipped with a brushless motor, there is a problem that the flat cable comes into contact with a rib provided in the housing or an edge portion of the rib, and the flat cable is disconnected.

  Further, there is a problem that the flat cable is sandwiched between the housings during assembly and the flat cable is disconnected.

  An object of the present invention is to provide a power tool that is compact, has good operability, and is highly reliable by preventing the flat cable from being disconnected.

To achieve the above object, the present invention comprises a housing having a motor housing portion and a handle housing portion, a brushless motor housed in the motor housing portion, and an inverter circuit for energizing the brushless motor with a drive current. An electric tool having a mounted first circuit board, a second circuit board having a circuit for controlling the inverter circuit, and a flat cable connecting the first circuit board and the second circuit board And a rib is provided in the vicinity of the mating surface of the divided housing, and a cushioning material made of a cloth material is formed on the flat cable portion that contacts the rib.

  According to the first aspect of the present invention, it is possible to provide an electric tool having excellent operability by reducing the diameter of the handle portion. In addition, a highly reliable electric tool can be provided by preventing disconnection of the flat cable.

<Embodiment 1>
A first embodiment of the present invention will be described in detail with reference to FIGS. The first embodiment will be described using a cordless impact driver as an electric tool.

  FIG. 1 is a partial cross-sectional view according to the first embodiment of the present invention, FIG. 2 is a schematic view according to the first embodiment of the present invention, and FIGS. The front view which showed the flat cable which concerns on 1 embodiment, FIG.3 (a-2) (b-2) is the front view which showed the flat cable which concerns on the 1st Embodiment of this invention.

  The configuration of the entire tool will be described with reference to FIG. The impact driver 50 according to the first embodiment of the present invention extends from one end (the left end in the drawing) to the other end (the right end in the drawing) along the same direction as the rotation shaft 11 of the brushless motor 3 to be described later. It is extended. The impact driver 50 includes a motor housing portion 50a made of a synthetic resin material that houses the brushless motor 3, and a power transmission housing portion 50b that houses the power transmission mechanism portion 4 that is formed continuously at the other end of the motor housing portion 50a. And a handle housing portion 50c depending from the motor housing portion 50a and the power transmission housing portion 50b. The front end of the power transmission housing 50b projects from the end of the anvil 10, and a tip tool such as a driver bit (not shown) is detachably inserted into the anvil square hole 10a and can be fixed by the mounting member 10b. ing. A bolt tightening bit can also be attached to the anvil square hole portion 10a as another tip tool.

  The motor housing portion 50a has a cylindrical shape, and a brushless motor 3 serving as a driving source is accommodated in the inner peripheral portion thereof.

  A power transmission mechanism portion 4 for transmitting the rotational force of the motor 3 to the anvil 10 as a rotational striking force is accommodated in the power transmission housing portion 50b continuous with the motor housing portion 50a. The power transmission mechanism unit 4 includes a speed reduction mechanism unit including a planetary gear 6 and a ring gear 7, and a spindle 8 and a hammer 9 that is slidable back and forth on the spindle 8 and is provided with a striking force by a spring 5. And an anvil 10 that is provided with a rotating impact force by the hammer 9 and can hold a tip tool (not shown) as described above.

  A battery pack case 1 serving as a driving power source for the brushless motor 3 is detachably mounted on the handle housing portion 50c at the lower end portion of the handle housing portion 50c. The battery pack case 1 accommodates a battery pack body made of a lithium ion battery, a nickel / cadmium battery or the like (not shown). Most of the battery pack main body is inserted and accommodated in the handle housing portion 50c. Alternatively, it is slidably attached to the handle housing portion 50c.

  The battery pack case 1 is electrically connected to the motor drive circuit device 2 via a trigger switch 50d provided in a part of the handle housing portion 50c. The motor drive circuit device 2 is electrically connected to a stator coil 12a (for example, a star-connected three-phase coil) of a brushless motor 3 to be described later, and rotationally drives the rotor 13 of the motor 3.

  In order to electrically drive the motor, an inverter circuit 22 including a known bridge circuit using a switching element for energizing a drive current to the stator coil 12a of the brushless motor 3, and a CPU or the like controlling the inverter circuit 22 The motor drive circuit device 2 is required. In particular, the inverter circuit 22 needs to pass a large drive current through the stator coil 12a, and a large-capacity output transistor such as an IGBT (insulated gate bipolar transistor) operating as a switching element must be used. For this reason, the power loss of the output transistor becomes large and heat generation becomes a problem, so it is necessary to dissipate heat. Therefore, the metal (heat dissipating plate) side of the output transistor 21 is disposed at a position close to the air inlet 17 provided in the end wall portion 50e of the motor housing, and no heat dissipating member is provided.

  The inverter circuit board 22 and the control circuit board 41 are connected by a flat cable 39a.

  According to the impact driver 50 configured as described above, when the operator pulls the trigger switch 50d while holding the handle housing portion 50c, the trigger switch 50d is turned on, and the operation of the impact driver 50 can be started.

  During the screw tightening operation, the rotational force of the motor 3 transmitted from the rotary shaft 11 is decelerated by the planetary gear 6 and the ring gear 7, and the rotational force is transmitted to the spindle 8, and the anvil 10 (tip tool) during the screw tightening. When a load torque exceeding a predetermined value is applied, the hammer 9 converts the rotational force into a striking force by the action of the spring 5. Thereby, the hammer 9 can apply a rotational striking force to the tip tool mounted on the anvil 10 and tighten the screw.

  Further, a cooling fan 15 and a sleeve 24 are provided on the rotating shaft 11 of the rotor 13, and the cooling fan 15 and the sleeve 24 rotate simultaneously when the rotor rotates. The front and rear of the rotating shaft 11 of the rotor 13 are supported by bearing members 11a. The stator 12 is provided with an inverter circuit 22 and a cover 25 so that the rotor 13 is sealed.

  An arrow 20 indicates the flow of cooling air.

  As shown in FIG. 2, a rib 38 is disposed in the vicinity of the mating surface of the housing. The ribs 38 can prevent the flat cable 39a from entering the mating surface of the housing.

  Also, as shown in FIGS. 2 and 3, by providing the cushioning material 40 at a local location of the flat cables 39a and 39b, the flat cable is disconnected due to contact with the rib provided in the handle housing portion 50c. This can be prevented.

  Further, a buffer material 40 is provided at a contact portion between the rib 38 and the flat cable 39a. Therefore, the flat cable 39a can be prevented from entering the mating surface of the housing, and the flat cable can be prevented from being disconnected.

  Further, even if stress is concentrated on the flat cables 39a and 39b due to vibration generated during the screw / bolt tightening operation, the flat cable can be prevented from being disconnected.

  From the above, when the flat cables 39a and 39b are accommodated in the handle housing portion 50c by providing the flat cables 39a and 39b with the cushioning material 40, the flat cables 39a and 39b are originally used for the degree of freedom and compactness. No damage. Therefore, it is possible to provide a highly reliable power tool that is excellent in operability by reducing the diameter of the handle portion and can prevent disconnection of the flat cable.

In addition, about the cushioning material 40 used for protection of the flat cables 39A and 39B, the cloth material of about 0.2 mm is selected as a member which does not lose to the compact part of a product and the edge part of an acute angle rib. As the cloth material, for example, acetate cloth is suitable.
<Embodiment 2>
A first embodiment of the present invention will be described in detail with reference to FIG. Since the second embodiment is the same as the first embodiment except for the flat cables 39a and 39b, the description thereof is omitted. FIG. 4A is a front view showing a flat cable according to the second embodiment of the present invention, and FIG. 4B is a side view showing the flat cable according to the second embodiment of the present invention.

  As shown in FIG. 4B, in the present embodiment, the entire flat cables 39 a and 39 b are covered with the buffer material 40. Compared to the first embodiment, one or more cushioning materials 40 are overlapped on one or both sides, particularly in places where the flat cables 39a and 39b may be damaged due to contact with the edge of the acute rib. The protection effect of the flat cables 39A and 39B is improved.

  From the above, when the flat cables 39a and 39b are accommodated in the handle housing portion 50c by providing the flat cables 39a and 39b with the cushioning material 40, the flat cables 39a and 39b are originally used for the degree of freedom and compactness. No damage. Therefore, it is possible to provide a highly reliable power tool that is excellent in operability by reducing the diameter of the handle portion and can prevent disconnection of the flat cable.

  In addition, about the cushioning material 40 used for protection of the flat cables 39A and 39B, the cloth material of about 0.2 mm is selected as a member which does not lose to the compact part of a product and the edge part of an acute angle rib. As the cloth material, for example, acetate cloth is suitable.

  In the embodiment of the present invention, the cordless type impact driver is used as the power tool. However, the present invention can be similarly applied to other power tools.

1 is a partial cross-sectional view according to a first embodiment of the present invention. 1 is a schematic diagram according to a first embodiment of the present invention. The external view which showed the flat cable which concerns on the 1st Embodiment of this invention. The external view which showed the flat cable which concerns on the 1st Embodiment of this invention. The external view which showed the conventional flat cable.

Explanation of symbols

  1 is a battery pack case, 2 is a motor drive circuit device, 3 is a brushless motor, 4 is a power transmission mechanism, 5 is a spring, 6 is a planetary gear, 7 is a ring gear, 8 is a spindle, 9 is a hammer, 10 is an anvil 10a is an anvil square hole part, 10b is a tip tool mounting member, 11 is a rotating shaft, 11a is a bearing member, 12 is a stator, 12a is a stator coil, 13 is a rotor, 15 is a cooling fan, 17 is an inlet, Cooling air (cooling gas), 21 output transistor, 22 inverter circuit board, 24 sleeve, 25 cover, 38 rib, 39a flat cable, 39b flat cable, 40 buffer material, 41 control circuit board , 50 is an electric tool (impact driver), 50a is a motor housing part, 50b is a power transmission housing part, and 50c is a handle housing. Ring portion, 50d trigger switch, 50e is an end wall of the motor housing.

Claims (1)

A housing having a motor housing portion and a handle housing portion, a brushless motor housed in the motor housing portion, a first circuit board on which an inverter circuit for energizing a drive current to the brushless motor is mounted, and the inverter circuit In a power tool having a second circuit board on which a circuit for controlling the circuit is mounted, and a flat cable connecting the first circuit board and the second circuit board, in the vicinity of the divided mating surfaces of the housing A power tool, wherein a rib is provided, and a cushioning material made of a cloth material is formed on the flat cable portion in contact with the rib.

Images