JP2006315121A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool, securing high cooling efficiency while reducing the size. <P>SOLUTION: An impact tool (this power tool) includes: a cooling fan 3 formed by radially fitting a plurality of blades 21 to a disk-like main board 22 and fitting a ring-like side plate 23 opposite to the main board to the blades 22; a fan chamber housing the cooling fan 3; and a driving source for driving the cooling fan 3 in rotation. The cooling fan 3 is provided with a projection (a reverse flow restraining means) 24 for restraining a reverse flow 17 of cooling air caused in a gap between the side plate 22 of the cooling fan 3 and a rib (a wall) 13 forming the fan chamber. The projection 24 is disposed on the side of the fan rotating shaft (inside in the radial direction) from the inner peripheral surface of the rib 13 forming the fan chamber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric tool including a cooling fan.

  In recent years, there is a high demand for miniaturization, high output, and low noise for electric tools that perform forward and reverse rotation, and accordingly, there is an increasing need to develop a motor cooling fan that is small and has high cooling capacity. Here, an impact tool as an example of an electric tool equipped with a motor cooling fan will be described with reference to FIG.

  FIG. 5 is a side sectional view of the impact tool, in which 10 is a housing forming a main body, 11 is a hammer case, and the rotation of the rotor 2 of the motor accommodated in the housing 10 is determined by the drive shaft. 5 is decelerated through the planetary reduction gear 6 and transmitted to the spindle 7. The rotation of the spindle 7 is transmitted from the hammer 8 accommodated in the hammer case 11 to the anvil 9, and the anvil 9 and a bit (not shown) attached to the tip of the anvil 9 are driven to rotate. The required tightening work is performed in response to the impact force.

  In FIG. 5, 1 is a switch for starting the rotor 2 of the motor, and 12 is a commutator of the motor.

  By the way, a cooling fan 3 for cooling a motor or the like is fixed to the drive shaft 5, and a plurality of intake ports 4 are formed on the outer periphery of the rear portion (left side in FIG. 5) of the housing 10. .

  6 is a sectional view around the cooling fan 3 of the impact tool, FIG. 7 is a perspective view of the cooling fan 3, and FIG. 8 is a sectional view of the cooling fan 3.

  The cooling fan 3 is a centrifugal fan, and as shown in FIGS. 7 and 8, a plurality of blades (impellers) 21 are radially attached to a disk-shaped main plate 22, and a ring-shaped facing the main plate 22. The side plate 23 is configured to be attached to the blade 21 (see, for example, Patent Document 1).

  Thus, when the cooling fan 3 rotates with the drive shaft 5, cooling air is introduced into the housing 10 from the intake port 4 as indicated by arrows a1 and a2 in FIG. The cooling air sequentially cools the commutator 12, the rotor 2, and the stator 14 (see FIG. 6) of the motor along the flow path formed in the housing 10, and is indicated by an arrow in FIG. As described above, the main flow 16 flows out from the inner diameter portion of the cooling fan 3 in the centrifugal direction, and is discharged from the plurality of discharge ports 15 formed in the housing 10 to the outside of the housing 10.

JP 2003-181778 A

  By the way, in order to increase the cooling efficiency of the motor in such an electric power tool, it is necessary to secure a larger air volume with the cooling fan. As a means for increasing the air volume of the cooling fan, a method of enlarging the cooling fan itself can be given. It is done.

  However, if the cooling fan is made larger, the product becomes larger, and it is impossible to meet the recent demand for miniaturization of electric tools.

  Therefore, development of a cooling fan that is small but highly efficient is desired. However, in the conventional electric tool, as shown in FIG. 6, the rib 13 and the cooling fan 3 that fix the stator 14 and form the fan housing chamber are fixed. A backflow 17 of the cooling air is generated in the gap, and this backflow 17 becomes a useless flow that is not used for cooling the motor, so that the efficiency of the cooling fan 3 cannot be increased.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electric tool capable of ensuring high cooling efficiency while achieving downsizing.

  To achieve the above object, the invention according to claim 1 is a cooling fan comprising a plurality of blades attached radially to a disk-shaped main plate, and a ring-shaped side plate facing the main plate attached to the blades; In an electric tool including a fan chamber that houses the cooling fan and a drive source that rotationally drives the cooling fan, the cooling fan generates cooling air generated in a gap between a side plate of the cooling fan and a wall that forms the fan chamber. The present invention is characterized in that a backflow suppressing means for suppressing backflow is provided.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the backflow suppressing means is constituted by a ring-shaped protrusion formed on a surface opposite to a blade of the side plate of the cooling fan. To do.

  According to a third aspect of the present invention, in the second aspect of the present invention, the protrusion is disposed closer to the fan rotation shaft than the inner peripheral surface of the wall forming the fan chamber.

  A fourth aspect of the invention is characterized in that, in the first aspect of the invention, the backflow suppressing means is composed of auxiliary blades formed on a surface opposite to the blades of the side plate of the cooling fan.

  The invention according to claim 5 is the invention according to claim 4, characterized in that the auxiliary blades are arranged closer to the fan rotation shaft than the inner peripheral surface of the wall forming the fan chamber.

  According to the first aspect of the present invention, the flow rate of the backflow of the cooling air generated in the gap between the side plate of the cooling fan and the wall forming the fan chamber is reduced by the backflow suppressing means, and the flow rate of the main flow of the cooling air is increased. Therefore, the cooling efficiency of the cooling fan can be increased without increasing the size of the cooling fan.

  According to the second aspect of the present invention, a maze-like bent portion (labyrinth portion) is formed in the reverse flow passage by the projection provided on the cooling fan, and the gap between the side plate of the cooling fan and the wall forming the fan chamber is formed. Since the flow rate of the reverse flow of the generated cooling air is kept small, the flow rate of the main flow of the cooling air can be increased, and the cooling efficiency of the cooling fan can be increased without increasing the size of the cooling fan.

  According to the third aspect of the present invention, since the protrusion is disposed on the fan rotation shaft side (inner diameter side) from the inner peripheral surface of the wall forming the fan chamber, the distance between the side plate and the wall of the cooling fan and the protrusion and the wall Backflow can be suppressed without reducing the distance to the power tool, and even if an impact is generated on the power tool due to a drop of the power tool, a problem such as contact between the cooling fan and the wall occurs. Can be prevented.

  According to the fourth aspect of the present invention, since the flow of the cooling air that opposes the direction of the reverse flow of the cooling air is generated by the fan effect of the auxiliary blades, the flow rate of the reverse flow of the cooling air can be suppressed to be small. The flow rate of the main flow of wind can be increased, and the cooling efficiency of the cooling fan can be increased without increasing the size of the cooling fan.

  According to the fifth aspect of the present invention, since the auxiliary blade is disposed closer to the fan rotation shaft side (inner diameter side) than the inner peripheral surface of the wall forming the fan chamber, the distance between the side plate and the wall of the cooling fan and the auxiliary blade Backflow can be suppressed without reducing the distance between the wall and the wall, and even if the power tool is impacted by dropping the power tool, etc. Can be prevented.

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

  FIG. 1 is a cross-sectional view of a periphery of a cooling fan of an impact tool as an embodiment of the electric tool according to the present invention, FIG. 2 is an enlarged detail view of a portion A in FIG. 1, and FIG.

  Since the basic configuration of the impact tool according to the present embodiment is the same as that of the conventional impact tool shown in FIG. 5, the description thereof will be omitted, and only the gist of the present invention will be described below.

  As shown in FIG. 1, a cooling fan 3 is attached to a drive shaft 5 that is rotationally driven by a rotor 2 of a motor housed in a housing 10 of an impact tool according to the present invention. The cooling fan 3 is a centrifugal fan, and as shown in FIG. 3, a plurality of blades (impellers) 21 are radially attached to a disk-shaped main plate 22 and a ring-shaped side plate 23 facing the main plate 22. Is attached to the blade 21, and a ring-shaped protrusion 24 is integrally provided on the surface of the side plate 23 on the side opposite to the blade 21.

  Thus, when the cooling fan 3 is rotated together with the drive shaft 5 in the housing 10 by the rotor 2 of the motor, the cooling air sucked into the housing 10 by the cooling fan 3 is indicated by an arrow in FIG. As shown, after cooling the rotor 2 and the stator 14 as a main flow 16, it flows out from the inner diameter portion of the cooling fan 3 in the centrifugal direction, and out of the housing 10 through a plurality of discharge ports 15 formed in the housing 10. And discharged.

  Here, as shown in FIG. 2, the main flow 16 of the cooling air flows from the flow 16 a flowing from the rotor 2 side, the flow 16 b passing between the blades 21 of the cooling fan 3, and the discharge port 15 of the housing 10. The flow 16c is discharged to the outside.

  By the way, a rib 13 that forms a fan storage chamber at the same time as fixing the cooling fan 3 and the stator 14 is integrally formed on the inner peripheral portion of the housing 10. Cooling discharged from the cooling fan 3 in the centrifugal direction is integrally formed. A part of the wind becomes a reverse flow 17 and flows through the gap between the rib 13 and the side plate 23 of the cooling fan 3 and is sucked into the cooling fan 3 again. Since the backflow 17 circulates only through the fan storage chamber in the housing 10 and is not discharged to the outside, the flow rate of the cooling fan 3 decreases when the flow rate increases.

  However, in the present embodiment, a ring-shaped protrusion 24 is provided on the side plate 23 of the cooling fan 3, and this protrusion 24 is on the fan rotation shaft side (radial direction) from the inner peripheral surface of the rib 13 of the housing 10. Therefore, a maze-shaped bent portion (labyrinth portion) is formed by the protrusion 24 in the gap between the rib 13 that is the flow path of the backflow 17 and the side plate 23 of the cooling fan 3. In this bent portion, a flow loss occurs in the backflow 17, so that the backflow 17 hardly flows and the flow rate of the backflow 17 is kept small.

  Thus, if the flow rate of the backflow 17 is kept small as described above, the pressure difference between the inlet portion and the outlet portion of the main flow 16b can be increased. As a result, the flow rate of the main flow 16 of the cooling air is reduced. Even if the cooling fan 3 is not enlarged, the cooling efficiency of the rotor 2 and the stator 14 by the cooling fan 3 can be increased.

  Further, since the protrusion 24 of the cooling fan 3 is disposed on the fan rotation shaft side (inward in the radial direction) with respect to the inner peripheral surface of the rib 13 of the housing 10, the distance between the side plate 23 of the cooling fan 3 and the rib 13 and the protrusion. The backflow 17 can be suppressed without reducing the distance between the rib 24 and the rib 13, and the cooling fan 3 and the rib 13 can There are no problems such as contact.

  Incidentally, in the above embodiment, the ring-shaped protrusion 24 is formed on the cooling fan 3, but as shown in FIG. 4, a plurality of protrusions 24 are provided on the surface opposite to the blade 21 of the inner peripheral portion of the side plate 23 of the cooling fan 3. The auxiliary blade 25 may be formed. In this case, the auxiliary blades 25 are arranged on the fan rotation shaft side (in the radial direction) with respect to the inner peripheral surface of the rib 13 of the housing 10.

  Thus, when the cooling fan 3 formed with a plurality of auxiliary blades 25 as shown in FIG. 4 is rotationally driven, a cooling air flow facing in the direction of the backflow 17 is generated by the fan effect of the auxiliary blades 25. Therefore, the flow rate of the backflow 17 can be kept small, the flow rate of the main flow 16 of the cooling air can be increased, and the rotor 2 and the stator 14 can be cooled by the cooling fan 3 without increasing the size of the cooling fan 3. Efficiency can be increased.

  Further, since the auxiliary blade 25 is arranged on the fan rotation axis side (radially inner side) from the inner peripheral surface of the rib 13 of the housing 10, the distance between the side plate 23 and the rib 13 of the cooling fan 3 and the auxiliary blade 25 and rib 13. The flow rate of the backflow 17 can be suppressed without reducing the distance, and the cooling fan 3 and the rib 13 are in contact with each other even if an impact is generated on the impact tool due to the impact tool dropping or the like. Can be prevented from occurring.

  In addition, when the flow rate of the backflow 17 is large as in the prior art, a problem that dust enters from the discharge port 15 is likely to occur. However, since the flow rate of the backflow 17 is suppressed, the effect that dust does not easily enter is also obtained. It is done.

  The present invention can be applied to not only an impact tool but also any other electric tool including a cooling fan to obtain the above effect.

It is sectional drawing of the cooling fan periphery of the impact tool which concerns on this invention. It is the A section enlarged detail drawing of FIG. It is a perspective view of the cooling fan of the impact tool which concerns on this invention. It is a perspective view which shows another form of the cooling fan of the impact tool which concerns on this invention. It is a sectional side view of the conventional impact tool. It is sectional drawing of the cooling fan periphery of the conventional impact tool. It is a perspective view of the cooling fan of the conventional impact tool. It is sectional drawing of the cooling fan of the conventional impact tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switch 2 Rotor 3 Cooling fan 4 Air inlet 5 Drive shaft 6 Planetary reduction gear 7 Spindle 8 Hammer 9 Anvil 10 Housing 11 Hammer case 12 Commutator 13 Rib (Wall which forms a fan chamber)
14 Stator 15 Discharge Port 16 Main Flow of Cooling Air 17 Backflow of Cooling Air 21 Blade 22 Main Plate 23 Side Plate 24 Protrusion (Backflow Control Means)
25 Auxiliary blades (backflow suppression means)

Claims (5)

A cooling fan in which a plurality of blades are attached radially to a disk-shaped main plate, and a ring-shaped side plate facing the main plate is attached to the blades, a fan chamber that houses the cooling fan, and a cooling fan. In an electric tool including a drive source for
An electric power tool characterized in that the cooling fan is provided with backflow suppression means for suppressing backflow of cooling air generated in a gap between a side plate of the cooling fan and a wall forming the fan chamber.   2. The electric tool according to claim 1, wherein the backflow suppressing means is constituted by a ring-shaped protrusion formed on a surface opposite to a blade of the side plate of the cooling fan.   The electric tool according to claim 2, wherein the protrusion is disposed closer to the fan rotation shaft than the inner peripheral surface of the wall forming the fan chamber.   2. The electric tool according to claim 1, wherein the backflow suppressing means is constituted by auxiliary blades formed on a surface opposite to the blades of the side plate of the cooling fan.   The power tool according to claim 4, wherein the auxiliary blade is disposed closer to a fan rotation shaft than an inner peripheral surface of a wall forming the fan chamber.

Images