JP2001328080A - Air intake and exhaust opening for motor cooling air in electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air intake and exhaust opening for motor cooling air capable of preventing the attraction of a metallic piece without lowering the cooling efficiency of a motor by solving a problem in a conventional battery- type electric tool such as an impact wrench or the like incorporated with a DC motor using a yoke of a permanent magnet that the metallic piece such as a clip or the like is attracted into a housing by the magnetic force of the yoke through the air intake and exhaust opening for cooling the motor. SOLUTION: A framed hole 21 sufficiently large to ensure the high air intake and exhaust efficiency is formed, and defined into definition holes 21a and 21a having a size capable of blocking the passage of the metallic piece to form air intake and exhaust openings 20A and 20B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power tool such as an impact wrench or a screw driver.
The present invention relates to intake and exhaust ports (an intake port and an exhaust port) for introducing cooling air from an electric motor into a housing.

[0002]

2. Description of the Related Art Generally, a DC motor using a permanent magnet for a stator is used for a battery-type power tool using a DC power supply as a power supply. The motor is housed inside the housing, and the stator is usually fixed to the inner surface of the housing. Usually, in order to cool the electric motor in this type of electric tool, cooling air is introduced into the housing through an intake port provided on the side of the housing, and the cooling air is circulated around the electric motor. The air is exhausted to the outside through an exhaust port provided on the side of the. Conventionally, the suction / exhaust port has been provided by forming a plurality of holes having a size necessary for efficient suction / exhaust on the side of the housing.

[0003]

However, the conventional intake and exhaust ports have the following problems. That is, when the power tool is placed on, for example, a work table, the housing is usually installed with the side surface of the housing laid sideways facing the work table, so that the suction and exhaust ports are directed to the work table. However, since the stator (permanent magnet) of the electric motor is disposed near the intake / exhaust port, a small metal piece on the workbench is attracted by the magnetic force of the stator through the intake / exhaust port, and in some cases, However, this metal piece may enter the housing through the suction / exhaust port, resulting in a malfunction of the power tool. This problem can be solved by making the intake and exhaust ports finer, but this will impair the intake and exhaust efficiency and, consequently, the cooling efficiency of the electric motor. The present invention has been made to solve this problem, and in a power tool using a DC motor that uses a permanent magnet for a stator as a drive source,
It is an object of the present invention to provide an intake / exhaust port capable of preventing a metal piece from entering a housing due to a magnetic force of a stator without impairing cooling efficiency of an electric motor.

[0004]

For this reason, the present invention provides an intake / exhaust port having the structure described in each of the above claims. According to the intake / exhaust port of the first aspect, the intake / exhaust port is provided in such a size that a large frame hole is divided into a plurality of sections and the metal piece does not pass through, so that the motor is fixed near these intake / exhaust ports. Even if the child (permanent magnet) is arranged, when the power tool is laid on a work bench or the like, the metal piece is prevented from entering the housing through the air suction / exhaust port. In this way, by defining a frame hole large enough to allow the metal piece conventionally provided to pass, by providing a small intake and exhaust port,
The metal piece can be prevented from entering without significantly reducing the conventional intake / exhaust efficiency. This configuration is particularly effective when a high performance magnet such as a rare earth magnet is used for the stator of the motor. In the present specification, a metal piece refers to a small metal object such as a cutting powder generated by a drilling operation of a steel plate or the like, a gem clip or a stapler (staple) needle left behind on a workbench.

According to the intake / exhaust port described in claim 2, the durability of the intake / exhaust port can be ensured. Conventionally, a step portion having a size corresponding to a frame hole is provided on a side portion of a housing to provide a thin portion, and a large number of fine pin holes having a diameter of about 1 mm (or less) are formed in the thin portion. However, there is a problem that the durability of the thin portion of the housing is low, and there is a problem that the intake / exhaust efficiency is reduced because the intake / exhaust port is too small. In addition, since a small pin hole is simultaneously formed in the molding step of the synthetic resin housing, it is necessary to provide a small-diameter pin portion in the mold, and this pin portion is as short as possible in consideration of its durability (breakage). As a result, there is a problem that the portion where the pin hole is provided must be set to be thinner than other portions of the housing. In this regard, according to the intake / exhaust port according to the second aspect, since the intake / exhaust port is formed by dividing a frame hole having a conventional size into a plurality of holes, the pin having the small diameter as described above is attached to the mold. There is no need to provide the housing, and therefore, it is not necessary to set the portion of the housing where the intake / exhaust port is provided to be thin.

According to the third aspect of the present invention, it is possible to efficiently prevent the metal pieces from entering while maintaining the intake and exhaust efficiency. Further, since the frame hole is divided into two parts in the front and rear directions in the machine length direction, it is not necessary to provide the pin having a small diameter as described above in the mold. For this reason, it is not necessary to form a thin portion on the side of the housing where the air intake / exhaust port is provided, whereby the durability of the housing can be ensured. Further, the intake and exhaust efficiency is not reduced.

[0007]

Next, an embodiment of the present invention will be described with reference to FIGS.
A description will be given based on FIG. FIG. 1 shows a rotary impact tool (so-called impact driver) 1 as an example of a power tool. The rotary impact tool 1 includes a tool main body 2 and a handle portion 3, which are formed by a housing 10 having a left-right split structure. A spindle 4 that is rotated by a built-in electric motor 30 protrudes from the tip of the tool body 2, and a bit attachment device 5 for attaching a driver bit (not shown) is attached to the tip of the spindle 4. . A battery 6 for supplying DC power to the electric motor is mounted at the tip of the handle portion 3. The embodiment described below is characterized by intake / exhaust ports 20 to 20 provided on the side of the housing 10 for intake / exhaust of cooling air for cooling the motor. The general configuration does not require any particular change as compared with the conventional configuration.

FIG. 2 shows the internal structure around the electric motor 30 built in the rear part of the tool body 2. The electric motor 30 is a DC motor driven by a DC power supplied from the battery 6 and includes a rotor 31 and a stator 32 located around the rotor 31. The rotor 31 is rotatably supported via bearings 33 and 34. A cooling fan 35 for cooling the motor is attached to the rear of the rotor 31. In the present embodiment, a so-called centrifugal fan is used as the cooling fan 35. Therefore, the motor cooling air is blown in the radial direction of the cooling fan 35. The stator 32 has a cylindrical yoke 36.
And is fixed along the inner periphery of the housing 10. For the stator 32, a rare earth magnet (permanent magnet) is used. Although not shown in the drawing, a commutator is provided at the rear of the rotor 31 (on the rear side of the cooling fan 35), and carbon brushes are slidably contacted with the commutator from both left and right sides. The cap of the brush holder holding the carbon brush is indicated by reference numeral 37 in the figure. This point is also the same as the conventional configuration, and no particular change is required in the present embodiment.

Next, the intake / exhaust ports 20 to 20 are provided symmetrically on both left and right sides near the rear of the housing 10. Hereinafter, as shown in FIG. 1, the intake / exhaust port 20 provided on one side (the left side as viewed from the user, the front side in FIG. 1)
20 will be described. The intake and exhaust ports 20 to 20 are
3 in the machine length direction (longitudinal direction of the tool body 2,
Arranged in columns. Two intake / exhaust ports 20A, 20A are arranged in the front row in the machine length direction, and four intake / exhaust ports 20B to 20B are arranged in the middle row in the machine length direction. Two intake / exhaust ports 20C, 20C are arranged behind the cap 37. The three rows of intake and exhaust ports 20A, 20B, and 20C are arranged vertically symmetrically with respect to the axis of the housing 10.

As shown in FIG. 2, the two intake and exhaust ports 20A, 20A on the front side in the machine length direction are located on the sides of the stator 32, and the four intake and exhaust ports 20B to 20B on the middle side in the machine length direction are provided with cooling fans. 35, and these air intake / exhaust ports 20 </ b> A and 20 </ b> B are located near the stator 32.
For this reason, a relatively large magnetic force (attraction force) of the stator 32 passes through the suction / exhaust ports 20A and 20B and the housing 10
To the outside. Since the two intake / exhaust ports 20C, 20C on the rear side in the machine length direction are provided at positions close to the rear corner of the housing 10 and sufficiently away from the stator 32, the stator 32 Does not reach the intake and exhaust ports 20C, 20C. As described above, the cooling fan 35 is a centrifugal fan. Therefore, when the cooling fan 35 is rotated by the activation of the electric motor 30, outside air (motor cooling air) is sucked into the housing 10 mainly through the intake / exhaust ports 20A, 20A on the front side in the machine length direction, and the air intake / exhaust on the middle side in the machine length direction. Mouth 20
The motor cooling air is blown out again through B and 20B,
Such a flow of motor cooling air is generated in the housing 10. In addition, the intake and exhaust ports 20C in the rear row in the machine length direction,
Outside air is inhaled even after passing through 20C. As described above, the motor cooling air sucked into the housing 10 through the intake / exhaust ports 20A, 20A on the front side in the machine direction (and the intake / exhaust ports 20C, 20C on the rear side in the machine direction) mainly emits the rotor 31 and the carbon brush. Cooling fan 3 while flowing around the cooling fan
5, the air is blown out of the housing 10 through the intake / exhaust ports 20B to 20B on the middle side in the machine length direction.

Next, the intake and exhaust ports 2 on the front and middle sides in the machine length direction
Details of OA, 20A, 20B-20B are shown in FIG. These intake and exhaust ports 20A, 20A, 20B-20
B has a horizontally long frame hole 21 having a long groove shape (oval shape) which is long in the machine length direction, and a partition wall 22 vertically extending in the longitudinal center of the frame hole 21. The partition wall 22 divides the frame hole 21 into two front and rear portions. Each of the two partition holes 21a, 21a has a size such that it can fit into a frame of about 3 mm square, and is formed to penetrate the housing 10. The partition wall 22 has a width of about 1 mm, and the thickness W thereof is set to be substantially the same as the thickness T of the housing 10. The size of both partition holes 21a, 21a is set to be as large as possible within a range that does not allow a metal piece such as a staple to pass through.

[0012] The intake and exhaust ports 20C, 20C on the rear side in the machine length direction.
As shown in FIG. 4, the holes are formed in the same shape and size as the frame holes 21 of the intake and exhaust ports 20A and 20B on the front and middle sides in the machine length direction. However, the intake / exhaust port 20C is the intake / exhaust port 2
It is not partitioned differently from 0A and 20B. Therefore,
Although the intake / exhaust port 20C has a size that allows metal pieces such as cutting chips to pass therethrough, the magnetic force of the stator 32 does not reach the intake / exhaust port 20C as described above. The metal piece does not enter the housing 10 through the suction / exhaust port 20C due to the suction force.

The intake and exhaust ports 20A, 20 constructed as described above
0B, a frame hole 21 large enough to allow a metal piece to pass through.
The partition wall 22 has a configuration in which the front and rear sections are divided into two, so that the intake and exhaust efficiency is not significantly impaired. Further, since the frame hole 21 is divided into two front and rear portions by the partition wall 22 at the center in the longitudinal direction, it is possible to prevent metal pieces from entering. As described above, even if the intake and exhaust ports 20A and 20B are arranged near the stator 32, it is possible to prevent the metal pieces from being sucked into the housing 10 by the magnetic force of the stator 32. From this, when the rotary impact tool 1 is placed on a worktable or the like with the rotary impact tool 1 laid on its side, the magnetic force of the stator 32 directly acts on the upper surface of the worktable via the intake / exhaust ports 20A and 20B. However, even in this case, small metal objects such as chips scattered on the work table or clips left on the work table are attracted by the magnetic force of the stator 32,
As a result, these metal pieces do not enter the housing 10 through the air suction / exhaust ports 20A and 20B, and thus the failure of the rotary impact tool 1 can be prevented.

Further, both partitioning holes 21a, 21a in each of the air intake / exhaust ports 20A, 20B are set to have a size that can be accommodated in a frame of about 3 mm square, which is a fine hole having a diameter of about 1 mm as in the prior art. Not. For this reason, unlike the case of the conventional fine hole, it is not necessary to provide a small-diameter pin portion in the molding die, so that the durability of the molding die can be improved and the thin-walled portion is provided on the housing 10 side. Since there is no need to provide a housing, the durability of the housing 10 (intake and exhaust ports 20
A, 20B and its impact resistance).

Various modifications can be made to the embodiment described above. For example, although the configuration in which the intake / exhaust ports 20C, 20C in the rear row in the machine length direction are not partitioned is illustrated, similar to the front and middle inlet / outlet ports 20A, 20B in the machine length direction, it is partitioned into two front and rear portions to more reliably. Metal piece housing 10
It is good also as composition which prevents invasion inside. In addition, the configuration in which the partition wall 22 is provided at one location in the center in the longitudinal direction of the frame hole 21 is illustrated, but a configuration may be provided in two or more locations to partition one frame hole 21 into three or more partition holes. Further, although the configuration in which the partition wall 22 is partitioned forward and backward by the partition wall 22 extending vertically is illustrated, a configuration in which the partition wall 22 is partitioned vertically by the partition wall extending horizontally may be used. Alternatively, the frame hole may be divided into four by a cross-shaped partition wall in which a horizontally extending partition wall and a vertically extending partition wall are combined. In short, a frame hole large enough to allow a metal piece such as a stapler needle to pass through is divided into at least two, and the partition hole formed by this is set to a size that does not allow the metal piece to pass through. This can prevent the metal pieces from being sucked into the housing 10 by the magnetic force of the stator 32 without impairing the intake / exhaust efficiency.

From the above, the present invention is effective for a power tool using a DC motor, in which an intake / exhaust port for cooling the motor is provided near a stator (permanent magnet) of the DC motor. This is more effective when a rare earth magnet is used for the stator. Accordingly, the present invention is not limited to the illustrated rotary impact tool, and can be applied to a motor cooling intake / exhaust port of other electric tools.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is an overall perspective view of a rotary impact tool.

FIG. 2 is a side view showing the internal structure around the electric motor of the rotary impact tool.

FIG. 3 is a perspective view of intake and exhaust ports on the front and middle sides in the machine length direction.

FIG. 4 is a perspective view of the intake / exhaust port on the rear side in the machine length direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotational impact tool (electric power tool) 2 ... Tool body 6 ... Battery 10 ... Housing 20 ... Intake / exhaust port 20A ... Intake / exhaust port on the front side in the machine length direction, 20B ... Inlet / exhaust port on the middle side in the machine length direction 20C ... Back side in the machine length direction Air intake / exhaust port 21 ... frame hole, 21a ... partition hole 22 ... partition wall 30 ... electric motor (DC motor) 31 ... rotor 32 ... stator (rare earth magnet) 35 ... cooling fan T ... housing thickness, W ... Compartment wall thickness

Claims (3)

[Claims] In a power tool having a built-in DC motor, a frame hole, which is a suction / exhaust port for sucking / exhausting motor cooling air from a side portion of a housing and having a size through which a metal piece can pass, is provided. Inlet / exhaust ports that are sized to block the passage of pieces. 2. The intake / exhaust port according to claim 1, wherein the partition wall defining the frame hole has a width in the thickness direction of the housing which is the same as the thickness of the housing. 3. The intake / exhaust port according to claim 1, wherein the intake / exhaust port has a long frame hole in the machine length direction of the tool body, and the frame hole is divided into two in the front and rear direction of the machine length.