JP4776320B2 - Electric tool - Google Patents

Description

  The present invention relates to an electric power tool such as an impact driver and a drill.

  The motor driver is connected to the electric driver in the longitudinal direction of the handle that the operator holds by hand, and the upper housing is crossed on the opposite side of the handle from the motor housing. The motor is housed in the motor housing. In addition, there is a structure in which a drive device is housed in the upper housing portion, and a transmission shaft that transmits power from a motor in the motor housing portion to a drive device in the upper housing portion is housed in the handle portion (for example, Patent Documents). 1). This type of electric driver removes the motor from the upper housing and reduces the size and weight of the upper housing, making it easy to perform operations such as screw tightening, and is also suitable for work in tight spaces. There is an advantage that.

  Further, the inventor has devised an electric driver having a structure as shown in FIGS. This electric driver is supported by the operator holding the handle portion 1, and when the operator pulls the trigger 2 with a finger, the motor 3 rotates and the power is transmitted to the drive device in the upper housing 5 by the transmission shaft 4. Then, the output shaft 6 protruding from the tip of the upper housing 5 is rotated, a bit (not shown) attached to the output shaft 6 is rotated, and screws are tightened.

Japanese Patent Laid-Open No. 2002-264042

  Since the electric driver pulls the power cord 7 from the end of the motor housing portion 8 opposite to the handle portion 1, the commutator 10 of the armature 9 of the motor 3 is close to the end side of the motor housing portion 8. To be arranged. The cooling fan 12 of the motor 3 is attached to the handle portion 1 side of the armature 9 opposite to the commutator 10.

  However, when the motor 3 is arranged in this manner, it is necessary to consider that the position of the cooling fan 12 is as far as possible from the handle portion 1 and the handle portion 1 is not thickened as shown in FIG. There is a problem that it becomes longer in the longitudinal direction of 1.

  As shown in FIG. 4, a discharge port 13 for cooling air a is provided in the vicinity of the cooling fan 12 of the motor housing portion 8, and this portion is in contact with the handle portion 1. For this reason, there is a problem that the cooling air a ejected from the discharge port 13 is likely to be applied to body parts such as the operator's hand and face, and the operator is likely to be uncomfortable.

  Further, as shown in FIG. 3, the control circuit 14 of the motor 3 is disposed in the motor housing portion 8, and the field effect transistor (FET) and the like included in the control circuit 14 are cooled by the cooling air a of the motor 3. Is desired. However, when the cooling air a flows into the motor housing portion 8 from the inlet 15 of the cooling air a at the end of the motor housing portion 8, the cooling air a mainly flows around the armature 9 toward the discharge port 13, and the control circuit 14. There is a problem that the flow rate of the cooling air “a” toward the direction becomes relatively small, and the cooling effect of the control circuit 14 tends to be lowered.

  Furthermore, since this type of electric tool extends so that the transmission shaft 4 intersects the upper housing portion 5, the upper housing portion 5 tends to swing when the motor 3 starts up, so that smooth operation is possible. Inhibit. Therefore, it is desired to reduce such a recoil as much as possible to suppress the swinging motion of the upper housing portion 5.

  In order to solve the above problems, the present invention employs the following configuration.

That is, in the invention according to claim 1, the motor housing portion (17) is continuous in the longitudinal direction of the handle portion (16), and the upper housing portion (18) is opposite to the motor housing portion (17) of the handle portion (16). The motor (19) is housed in the motor housing part (17), the drive device is housed in the upper housing part (18), and the motor (19) is connected to the drive device in the handle part (16). In the electric tool in which the transmission shaft (32) for transmitting power is housed , the cooling fan (25) of the motor (19) is disposed between the core (26) of the armature (20) and the commutator (24). The cooling air (a) intake port (29) is provided in the motor housing portions (17) on both ends of the armature (20), respectively , and the cooling air (a) discharge port (27). The motor housing part (17) Characterized in that provided at a position opposite to the cooling fan (25).

Further, the invention according to claim 2 is the electric tool according to claim 1, wherein the control circuit (30) of the motor (19) is attached at a position facing the cooling fan (25) in the motor housing part (17). It is characterized by that.

According to the first aspect of the present invention, the motor housing portion (17) is continuous in the longitudinal direction of the handle portion (16), and the upper housing portion (18) is opposite to the motor housing portion (17) of the handle portion (16). The motor (19) is housed in the motor housing part (17), the drive device is housed in the upper housing part (18), and the motor (19) is connected to the drive device in the handle part (16). In the electric tool in which the transmission shaft (32) for transmitting power is housed , the cooling fan (25) of the motor (19) is disposed between the core (26) of the armature (20) and the commutator (24). The cooling air (a) intake port (29) is provided in the motor housing portions (17) on both ends of the armature (20), respectively , and the cooling air (a) discharge port (27). The cooling of the motor housing (17) Since provided at a position opposite to the fan (25) it can be cooling air (a) to prevent operator's hands, from such a body part such as the face.

According to the invention according to claim 2, in the electric tool according to claim 1, the control circuit (30) of the motor (19) is attached at a position facing the cooling fan (25) in the motor housing part (17). Therefore, the cooling air (a) flows into the motor housing part (17), flows from around the armature (20) toward the control circuit (30), and then flows out from the discharge port (27). become. Therefore, it is possible to increase the cooling efficiency of the control circuit (30), to suppress the heat generation of elements such as FETs included in the control circuit (30), and to extend the life.

  The best mode for carrying out the invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, this electric tool is specifically configured as an impact driver.

  The housing of the impact driver includes a handle portion 16 that is held by an operator, a motor housing portion 17 that extends in the longitudinal direction of the handle portion 16, and a handle portion 16 that is continuous with the handle portion 16 on the opposite side of the motor housing portion 17. The housing part 18 is provided, and is formed in half in the left-right direction as a whole (direction perpendicular to the paper surface of FIG. 1). The split part is joined, and a set screw (not shown) is passed to the left and right to assemble as an integral housing.

  As shown in FIGS. 1 and 2, a motor 19 is accommodated in the motor housing portion 17, and the motor 19 is accommodated so that the center line of the armature 20 faces the handle portion 16. That is, the shaft of the armature 20 extends from the motor housing portion 17 into the handle portion 16 and is supported at both ends by a bearing 21 fixed in the handle portion 16 and a bearing 22 fixed at the end of the motor housing portion 17. Has been.

  Further, since the power cord 23 of the motor 19 is drawn from the end of the motor housing portion 17 opposite to the handle portion 16, the commutator 24 of the armature 20 is opposite to the handle portion 16 of the motor housing portion 17. It is arrange | positioned adjacent to the terminal side of. The cooling fan 25 of the motor 19 is attached to the handle 16 side opposite to the commutator 24 of the armature 20 so as not to obstruct the installation of the commutator 24. In this embodiment, Then, the core 26 of the armature 20 is shifted to a position where the armature 20 is biased toward the handle portion 16 side, and is mounted in the space between the core 26 and the commutator 24 formed as a result. As a result, the cooling fan 25 is positioned substantially in the center in the longitudinal direction in the motor housing portion 17, so that the outlet 27 for the cooling air a faces the side of the motor housing portion 17 so as to face the cooling fan 25. Is provided. Further, the cooling air intake port 28 is also provided at the end of the motor housing portion 17 as in the prior art. However, the cooling air a discharge port 13 conventionally provided on the handle portion 16 side of the motor housing portion 17 (see FIG. 4). ), An intake port 29 for cooling air a is provided. As a result, it is possible to prevent the cooling air a from being blown out toward the hand or the like of the operator who holds the handle portion 16 in the related art.

  Further, as a result of the position change of the cooling fan 25 toward the commutator 24 in this way, as shown in FIGS. 1 and 2, the handle portion 16 side of the armature 20 is simplified, and the shaft end of the armature 20 is It is possible to enter the handle portion 16 with the bearing 21 as deeply as possible. As a result, the power tool of this embodiment is shortened in the longitudinal direction of the handle portion 16 as apparent from the comparison between FIG. 1 and FIG. 3, and the motor 19 approaches the handle portion 16. The center of gravity of the power tool approaches the handle portion 16, and the stability of the power tool is improved.

  As shown in FIG. 1, a control circuit 30 of the motor 19 is attached in the motor housing portion 17 so as to face the cooling fan 25. The control circuit 30 is supported by the motor housing part 17 via the heat sink 30a. When the cooling fan 25 rotates with the rotation of the armature 20, as shown in FIG. 1 and FIG. 2, the cooling air a flows into the intake port 29 on the handle portion 16 side and the intake port 28 on the end side of the motor housing portion 17. From the discharge port 27 to the outside of the motor housing part 17 after flowing from the periphery of the armature 20 toward the control circuit 30. As a result, not only the cooling efficiency of the motor 19 but also the cooling efficiency of the control circuit 30 is increased, the heat generation of the elements such as FETs included in the control circuit 30 that are likely to generate heat is suppressed, and the life extension effect is enhanced.

  A trigger 31 for turning the motor 19 ON / OFF via the control circuit 30 is provided at the upper end of the handle portion 16. When the trigger 31 is pulled and operated with the finger of the hand gripping the handle portion 16, the motor 19 is activated by a signal output from the control circuit 30.

  As shown in FIG. 1, a transmission shaft 32 that transmits power from the motor 19 to the drive device is housed in the handle portion 16. The transmission shaft 32 extends parallel to the axis of the armature 20 and is supported at both ends by a bearing 33 attached in the handle portion 16 and a bearing 34 attached in the upper housing portion 18. A large gear 35 is fixed to the lower end of the transmission shaft 32, and the large gear 35 meshes with a pinion 36 formed at the shaft end of the armature 20. Thereby, the rotation of the armature 20 is decelerated and transmitted to the transmission shaft 32.

  As shown in FIG. 1, the drive device is accommodated in the upper housing portion 18. The drive device has a shaft 37, and this shaft 37 extends in the upper housing portion 18 in a direction intersecting the center line of the transmission shaft 32. A large bevel gear 38 is fixed to the rear end portion of the shaft 37, and a small bevel gear 39 fixed to the upper end of the transmission shaft 32 is engaged with the large bevel gear 38. Thereby, the rotation of the transmission shaft 32 is decelerated and transmitted to the shaft 37. An output shaft 40 is connected to the tip of the shaft 37 via a hammer mechanism. The tip of the output shaft 40 protrudes from the tip of the upper housing portion 18 to the outside, and a bit (not shown) is detachably attached to the protruding portion.

  The front inner case 41 and the rear inner case 42 are fitted in the upper housing portion 18. The shaft 37 is accommodated from the rear inner case 42 to the front inner case 41, and the output shaft 40 is accommodated in the front inner case 41. The rear end portion of the shaft 37 is supported in the rear inner case 42 via a bearing 43, and the front end portion of the shaft 37 is supported by being inserted into the cavity of the output shaft 40. The output shaft 40 is supported by a bearing 44 held in the front inner case 41.

  The hammer mechanism is configured as follows. That is, the shaft 37 protrudes forward from the rear inner case 42 into the front inner case 41, and a spiral groove 37a having both ends closed is formed at the tip. A cylindrical hammer 45 is covered at the front end of the shaft 37, and a vertical groove 45 a having a closed rear end is formed on the inner surface of the hammer 45. The hammer 45 is connected to the shaft 37 by a steel ball 46 inserted so as to straddle between the spiral groove 37a and the longitudinal groove 45a. The hammer 45 is always urged forward by a compression coil spring 47 provided around the tip of the shaft 37, and stops at a position where the ball 46 contacts the front end of the spiral groove 37a and the rear end of the vertical groove 45a. . When the shaft 37 rotates, the hammer 45 retreats while being twisted on the shaft 37 against the urging force of the compression coil spring 47 by the engagement of the spiral groove 37a, the longitudinal groove 45a and the ball 46, and then the compression coil spring. Due to the elasticity of 47, the hammer 45 advances while being twisted in the opposite direction on the shaft 37, and the hammer 45 performs reciprocating angular motion while repeating this advance and retreat. Two arms 40a project radially from the rear end of the output shaft 40, and two claw pieces (not shown) projecting from the hammer 45 abut each arm 40a in the circumferential direction. As described above, when the hammer 45 reciprocates while moving forward and backward, the claws of the hammer 45 repeatedly strike the arm 40a of the output shaft 40 in the circumferential direction, and the output shaft 40 is intermittently moved in one direction. Rotate. Thus, screws are tightened by a bit (not shown) fixed to the output shaft 40.

  As described above, since the upper housing portion 18 extends in a direction intersecting the transmission shaft 32 together with the shaft 37 and the output shaft 40 therein, the motor 19 is started and the rotation is performed via the transmission shaft 32 through the shaft. When being transmitted to 37 and the output shaft 40, the upper housing portion 18 tries to swing by the reaction. In order to suppress this, in this embodiment, as shown in FIG. 1, the intermediate portion of the transmission shaft 32 is formed as a small-diameter portion 32a that is thinner than the other portions. As a result of the transmission shaft 32 being formed in this way, the reaction at the start of the motor 19 is alleviated and the swinging motion of the impact driver is alleviated.

  Next, the operation of the impact driver configured as described above will be described.

  The impact driver is supported by the operator holding the handle portion 16 by hand. As a result of the position of the cooling fan 25 being changed to the commutator 24 side, the impact driver has a shaft end of the armature 20 that penetrates into the handle portion 16 as much as possible together with the bearing 21 and is shortened in the longitudinal direction of the handle portion 16. Since the center of gravity of the impact driver is close to the handle portion 16, the operator can stably support the impact driver with the hand holding the handle portion 16.

  When the operator pulls and operates the trigger 31 with the finger of the hand having the handle portion 16, the motor 19 is rotated by a command from the control circuit 30. The rotation of the armature 20 of the motor 19 is decelerated stepwise to the transmission shaft 32 and the shaft 37 and transmitted to the output shaft 40. Rotation is transmitted to the output shaft 40 via a hammer mechanism, and a bit (not shown) attached to the tip of the output shaft 40 rotates the screw.

  When the motor 19 is started, the upper housing portion 18 tries to swing around the handle portion 16 by the reaction, but the small-diameter portion 32a formed narrower than the other portion of the transmission shaft 32 alleviates this reaction. . Thereby, the swinging phenomenon of the impact driver is reduced, and proper screw tightening can be performed.

  When the armature 20 of the motor 19 rotates, the cooling fan 25 also rotates integrally with the armature 20 and takes the cooling air a into the motor housing portion 17 from the intake ports 28 and 29. Since the intake port 29 is opened instead of the conventional discharge port on the handle portion 16 side of the motor housing portion 17, the cooling air a is not sprayed on the hand or the like of the operator holding the handle portion 16.

  When the cooling fan 25 rotates with the rotation of the armature 20, the cooling air a flows into the motor housing portion 17 from the intake port 29 on the handle portion 16 side and the intake port 28 on the end side of the motor housing portion 17. Then, after flowing from around the armature 20 toward the control circuit 30, it is discharged from the discharge port 27 to the outside of the motor housing portion 17. The cooling air a flowing in the motor housing portion 17 cools the motor 19 and further flows toward the control circuit 30 to cool the control circuit 30. As a result, the heat generation of an element that is particularly likely to generate heat, such as an FET included in the control circuit 30, is suppressed, and the life extension effect is enhanced.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the various embodiments described above, and various modifications can be made without departing from the scope of the present invention. For example, although the impact driver has been described as an example in the above embodiment, the present invention is applicable to other power tools such as a drill in addition to the impact driver.

It is a side view which shows the inside of the electric tool which concerns on this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. It is a side view which shows the inside of the conventional electric tool. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 16 ... Handle part 17 ... Motor housing part 18 ... Upper housing part 19 ... Motor 20 ... Armature 24 ... Commutator 25 ... Cooling fan 26 ... Core 27 ... Discharge port 29 ... Intake port 30 ... Control circuit 32 ... Transmission shaft 32a ... small diameter part a ... cooling air

Claims (2)

The motor housing part is connected in the longitudinal direction of the handle part, the upper housing part is connected to the handle part opposite to the motor housing part, the motor is stored in the motor housing part, the driving device is stored in the upper housing part, and the handle part is stored in the handle part. Is a power tool that houses a transmission shaft that transmits power from a motor to a drive device .
The motor cooling fan is mounted between the armature core and the commutator, and cooling air intake ports are provided in the motor housing portions on both ends of the armature, respectively , and the cooling air discharge port Is provided at a position facing the cooling fan of the motor housing portion. 2. The electric tool according to claim 1, wherein the motor control circuit is attached at a position facing the cooling fan in the motor housing portion.

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