JP2007268634A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool, having a compact housing 2 for the power tool, not increasing the size of a grip, having the favorable cooling efficiency of a rotation control electronic part 12, decreasing a failure caused by overheating and the deterioration of output efficiency and having high reliability. <P>SOLUTION: In this power tool, the grip is provided on the lower part of the housing 2 storing a motor 3 and a cooling fan 4 in the rear part and a rotary drive transmitting part 7 taking the motor 3 as a driving source in the front. A space S is formed inside between the rear end lower part of the housing 2 and the upper part of the rear end of the grip, and a rotation control electronic part 12 for controlling the rotation of the motor 3 and a radiating member 16 for radiating heat generated from the rotation control electronic part 12 are disposed in the space S. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power tool such as an impact driver, and more particularly to an electric power tool capable of efficiently cooling a rotation control electronic component that controls rotation of a motor.

  In general, some electric power tools such as impact drivers are equipped with rotation control electronic components such as FETs in order to control the number of rotations by pulling a trigger switch. Such a power tool can be rotated at a low speed when the pull amount of the trigger switch is shallow, and can be rotated at a high speed when pulled deeply. However, the rotation control electronic component generates a high temperature due to heat generation particularly during rotation at a low speed, so that the output efficiency is lowered or breaks down. Therefore, a means for preventing overheating of the electronic component for rotation control is required.

In order to meet such demands, for example, a heat radiating chamber provided with an air flow path is further formed by a heat radiating plate behind an opening for taking air into a motor cooling fan, and is rotated inside the heat radiating plate. Known are those in which control electronic parts are fixed (Patent Document 1), those in which a heat dissipation block is provided at the lower part of the grip of an electric tool, and rotation control electronic parts are attached to the heat dissipation block (Patent Document 2). Yes.
Japanese Patent Laid-Open No. 11-300656 JP 2005-74613 A

  However, since the thing of patent document 1 is the structure which forms the heat radiating chamber into which air flows with a heat sink behind the cooling fan of a motor, there exists only a fault that the volume of the whole housing increases, and it becomes large and heavy. However, since the flow path of the cooling air sent from the cooling fan to the motor becomes long, there is a problem that the cooling efficiency of the motor is lowered. In addition, since there is no extra space inside the grip, there is a problem with heat dissipation and the grip itself has to be enlarged, so that the grip becomes thick. It was.

  The present invention has been made in view of the above problems, and the power tool housing is compact, it is not necessary to increase the grip size, the cooling control electronic components have good cooling efficiency, and there is a failure or output due to overheating. It is an object of the present invention to provide a highly reliable power tool with little reduction in efficiency.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a front side of a housing in which a motor and a cooling fan are housed in a rear part and a rotational drive part using the motor as a drive source is housed in a front part. In a power tool in which a grip is provided at the lower part of the housing, a space is formed inside the rear end lower part of the housing and the rear end upper part of the grip, and the motor is rotated in this space part. An electronic component for rotation control to be controlled and a heat dissipating member for dissipating heat generated from the electronic component for rotation control are arranged.

  The invention according to claim 2 is further characterized in that an intake hole for taking in air to be sent to the cooling fan is formed in the housing in the vicinity of the electronic component for rotation control.

  According to the first aspect of the present invention, the rotation control electronic component that controls the rotation of the motor and the rotation control electronic component are generated in the inner space between the rear end lower portion of the housing and the rear end upper portion of the grip. Since the space is close to the motor cooling fan, the air flow is possible when the cooling fan rotates, so the cooling efficiency of the electronic components for rotation control Therefore, it is possible to provide a highly reliable power tool with few failures due to overheating.

  Further, the space portion is formed inside the rear end lower part of the housing and the rear end upper part of the grip, and can be formed without providing a large space in the housing. The grip size is not impaired.

  According to the second aspect of the present invention, since the intake hole for taking in the air sent to the cooling fan is formed in the vicinity of the electronic component for rotation control, the cooling efficiency of the electronic component for rotation control is good.

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

  FIG. 1 is a side view of an impact driver according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line XX of FIG. 1, and FIG. FIG.

  In the above figure, reference numeral 1 denotes a tool body of the impact driver. A motor 3 is built in the rear part of the housing 2 of the tool body 1, a cooling fan 4 is provided in front of the motor 3, and a speed reduction part 5 using a planetary gear or the like and a rotary drive part 6 such as a hammer or anvil are provided in front of the motor 3. And a rotational drive transmission portion 7 is provided at the front end of the housing 2. A driver bit (not shown) is detachably attached to the tip of the rotational drive transmission unit 7.

  A grip 8 is provided at the lower part of the housing 2. A motor actuation trigger 9 is disposed at the front of the grip 8. The grip 8 is provided with a switch 10 for opening and closing the contact in conjunction with the operation of the trigger 9, and a battery power source 11 is also provided. The switch 10 is electrically connected to the motor 3, an FET 12 described later, and a battery power source 11.

  The FET 12 is an electronic component for rotation control for controlling the rotation of the motor 3, and is arranged in a space S formed inside the lower portion of the rear end of the housing 2 and the upper portion of the rear end of the grip 8. That is, as described above, the motor 3 is disposed at the rear portion of the housing 2, and the cooling air intake hole 13 is formed around the motor 3 of the housing 2. Similarly, an exhaust hole 14 is formed around the cooling fan 4 disposed in front of the motor 3. A partition plate 15 is attached between the motor 3 and the cooling fan 4. This is because the air blown outward by the cooling fan 4 does not return to the intake hole 13 side but is discharged from the exhaust hole 14.

  A heat radiating member 16 formed in an arc shape along the lower surface of the motor 3 is attached to the lower portion of the motor 3, and the rotation control electronic component 12 is fixed to the lower portion of the fin 17 of the heat radiating member 16. The heat dissipating member 16 and the rotation control electronic component 12 are disposed in the vicinity of the intake hole 13 of the housing 2.

  According to the above configuration, when the trigger 9 is pulled and operated, the motor 3 is actuated, and the rotation of the motor 3 is decelerated by the decelerating unit 5 and transmitted to the rotation drive transmitting unit 7, and the driver bit rotates to perform screwing work. Is called. Since the electronic component 12 for rotation control is provided, the number of rotations of the motor 3 increases as the pulling amount increases depending on the pulling amount of the trigger 9. Although the motor 3 generates heat while continuing this operation, the cooling fan 4 also rotates simultaneously with the rotation of the motor 3, so that outside air is taken into the housing 2 from the intake hole 13, and after cooling the motor 3, the exhaust hole 14 is discharged.

  Simultaneously with the motor 3, the rotation control electronic component 12 also generates heat. However, since the electronic component 12 for rotation control is attached to the heat radiating member 16 and the heat radiating member 16 is provided in the vicinity of the intake hole 13, it is arranged in the flow of the cooling air. . Further, since the rotation control electronic component 12 is also arranged in the air flow, it is cooled by directly contacting the air, and the heat radiating member 16 is also in contact with the cooling air. The self-heating of the rotation control electronic component 12 is also radiated and cooled via the heat radiating member 16. Further, since the rotation control electronic component is disposed in the vicinity of the intake hole 13, it is not directly affected by the heat generated by the motor 3.

  Therefore, the cooling efficiency of the rotation control electronic component 12 is good, and there is little failure due to overheating or a decrease in output efficiency, and a highly reliable power tool can be provided.

  Moreover, the space S in which the heat dissipating member 16 and the rotation control electronic component 12 are installed is determined from the diameter of the motor 3 determined from the predetermined use of the electric power tool and the diameter of the cooling fan 4 determined from the cooling capacity. Since the housing 2 can be provided within a range that satisfies the requirements of the smooth form required by the design due to the outer diameter, strength, workability, aesthetics, manufacturability, etc., the size of the housing 2 is not adversely affected. . Also, the grip size can be kept slim.

  In addition, although the above-mentioned embodiment is related with an impact driver, this invention is not limited to an impact driver. The present invention can also be applied to an apparatus using electronic components for controlling the rotation of a motor, such as an electric tool such as an electric drill.

The side view of the impact driver which concerns on one Embodiment of this invention Sectional view on the XX line of FIG. Partial side view of an impact driver with the main section shown in cross section

Explanation of symbols

DESCRIPTION OF SYMBOLS S Space part 2 Housing 3 Motor 7 Rotation drive transmission part 12 Electronic component for rotation control 13 Intake hole 16 Heat radiation member

Claims (2)

A power tool with a motor and cooling fan at the rear, a rotation drive transmission part at the front of the housing that houses the rotation drive with the motor as a drive source at the front, and a grip at the lower part of the housing In
A space portion is formed inside the rear end lower portion of the housing and the rear end upper portion of the grip, and generated in the space portion from the rotation control electronic component for controlling the rotation of the motor and the rotation control electronic component. An electric tool characterized by disposing a heat dissipating member that dissipates heat.   The power tool according to claim 1, wherein an intake hole for taking in air to be sent to the cooling fan is formed in the housing near the electronic component for rotation control.

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