WO2017208711A1

WO2017208711A1 - Electric tool

Info

Publication number: WO2017208711A1
Application number: PCT/JP2017/016970
Authority: WO
Inventors: 健冨山; 央松下
Original assignee: 日立工機株式会社
Priority date: 2016-05-31
Filing date: 2017-04-28
Publication date: 2017-12-07

Abstract

In order to provide an electric tool that can effectively reduce the backflow of cooling air toward a motor body, an electric drill 1 has a housing 2 in which an exhaust port 25 is formed, a motor 3 stored in the housing 2, a fan 4 that rotates with rotation of a rotary shaft 31 of the motor 3, and a fan guide 5. The fan 4 is stored in a fan storing part 27 of the housing 2. The fan guide 5 has a base part 51 facing the outer peripheral part of blades 42 of the fan 4, and a cover part 54 having an annular shape and facing the surface of the fan 4 on the side of a stator 32 of the motor 3 in the axial direction of the rotary shaft 31. The cover part 54 has a first cover part 54A, and a second cover part 54B having a greater radial length than the first cover part 54A. The first cover part 54A is provided on the radially inner side of a region R1, where the exhaust port 25 is formed, on a peripheral wall surface 27B that defines the fan storing part 27, and the second cover part 54B is provided on the radially inner side of a region R2, where the exhaust port 25 is not formed, on the peripheral wall surface 27B.

Description

Electric tool

The present invention relates to a power tool.

2. Description of the Related Art Conventionally, there is known an electric tool that is provided with a centrifugal fan on a rotating shaft of a motor and cools a motor main body or the like with cooling air generated by the rotation of the centrifugal fan. An electric tool including such a centrifugal fan may be provided with a fan guide for adjusting the flow of cooling air (see, for example, Patent Documents 1 and 2).

JP2003-181778 JP-A-10-153194

The centrifugal fan discharges the cooling air after cooling the motor body toward the outside in the radial direction. When there is a wall surface such as a housing on the radially outer side of the centrifugal fan, the discharged cooling air may collide with the wall surface and flow backward to the motor body side. When the cooling air heated by the heat of the motor body flows backward, there is a problem that the cooling efficiency of the motor body is lowered.

This invention is made | formed in view of the said background, The objective is to provide the electric tool which can suppress the backflow of cooling air and can cool a motor efficiently.

In order to solve the above-described problems, the present invention provides a motor having a rotating shaft, a centrifugal fan having an impeller rotated by rotation of the rotating shaft, and an annular shape on the motor side surface of the impeller in the axial direction of the rotating shaft. An opposing first wall portion, and a second wall portion provided on the radially outer side of the impeller and extending in the axial direction so as to face the outer peripheral portion of the impeller, the second wall portion being an outer peripheral portion And a second portion having a wall surface facing the outer peripheral portion, and the first wall portion is disposed on the radially inner side of the first portion. A second opposing portion disposed on the radially inner side of the second portion, and the radial length of the second opposing portion is longer than the radial length of the first opposing portion. An electric tool characterized by the above is provided.

According to such a configuration, since the length in the radial direction is increased for the second facing portion of the first wall portion, the cooling air warmed by the heat of the motor is radially outward by the rotation of the impeller. Even after returning to the impeller side after colliding with the inner wall of the second part, it is possible to suppress backflow to the motor side. Therefore, the amount of cooling air that flows back to the motor side by the second facing portion is reduced, and the cooling efficiency of the motor can be improved. Further, by reducing the amount of cooling air that flows back to the motor side, a larger amount of cooling air is sent to the motor. Therefore, the cooling efficiency of the motor can be improved without significantly reducing the amount of cooling air that cools the motor.

Further, since the length in the radial direction of the first facing portion is shorter than that of the second facing portion, the cooling air can be smoothly guided from the motor side to the exhaust port formed radially outward of the impeller. Is possible. Therefore, a sufficient amount of cooling air can be secured, and the motor can be more efficiently cooled. *

Moreover, in the said structure, it is preferable that a 1st wall part comprises a part of fan guide which guides the flow of the cooling air produced | generated by rotation of an impeller.

According to such a configuration, the first wall portion is configured as a part of the fan guide. That is, simply by making the radial length of the portion corresponding to the second facing portion of the fan guide (first wall portion) longer than the radial length of the portion corresponding to the first facing portion, And generation | occurrence | production of the backflow of cooling air can be suppressed effectively. In addition, since it is not necessary to change the configuration other than the fan guide, it is possible to reduce the manufacturing cost of the power tool and to avoid complication of the manufacturing process.

Moreover, in the said structure, it is preferable that a 2nd wall part comprises a part of housing which accommodates a motor and a centrifugal fan.

According to such a structure, since the 2nd wall part is comprised as a part of housing, compared with the case where a 2nd wall part and a housing are comprised as a different body, the number of parts required for manufacture of an electric tool Can be reduced, and the manufacturing cost can be suppressed and the assemblability can be improved.

Further, in the above configuration, the housing may be formed with an intake port at a position different from the exhaust port in the axial direction, and at least a part of the motor may be disposed between the intake port and the exhaust port in the axial direction. preferable.

According to such a structure, a part of motor is arrange | positioned between an inlet port and an exhaust port in the axial direction of a rotating shaft. That is, since the motor is arranged on the flow path through which the cooling air flows from the intake port to the exhaust port, the motor that is a heating element can be efficiently cooled. Further, when the motor is a brushless motor, the inverter circuit board can be efficiently cooled if the inverter circuit board for controlling the brushless motor is arranged in the vicinity of the motor.

The present invention further includes a motor having a rotating shaft, a centrifugal fan rotating by rotation of the rotating shaft, and a centrifugal fan and motor in the axial direction of the rotating shaft so as to guide a flow of cooling air generated by rotation of the centrifugal fan. A wall portion extending in the radial direction, and a housing that houses the motor and the centrifugal fan and has a wall surface and an exhaust port on the radial outside of the centrifugal fan, the wall portion having an opening through which cooling air flows, An electric tool characterized in that the distance from the center of the rotating shaft in the vicinity of the wall surface to the inner peripheral surface of the opening is shorter than the distance from the center of the rotating shaft in the vicinity of the exhaust port to the inner peripheral surface of the opening. I will provide a.

According to such a configuration, since the distance of the opening on the wall surface side is shorter than the distance of the opening on the exhaust port side, that is, the wall portion is longer on the wall surface side than the exhaust port side, the motor Even if the cooling air warmed by the heat of the fan is discharged radially outward by the rotation of the centrifugal fan and then collides with the wall surface and returns to the centrifugal fan side, the backflow to the motor side can be suppressed. It becomes possible. Therefore, the amount of cooling air flowing back to the motor side is reduced, and the cooling efficiency of the motor can be improved. Further, by reducing the amount of cooling air that flows back to the motor side, a larger amount of cooling air is sent to the motor. Therefore, the cooling efficiency of the motor can be improved without significantly reducing the amount of cooling air that cools the motor.

The present invention further includes a motor having a rotating shaft, a centrifugal fan rotating by the rotation of the rotating shaft, and a centrifugal fan and a motor side in the axial direction of the rotating shaft so as to guide a flow of cooling air generated by the rotation of the centrifugal fan. An opposing wall, and a housing that houses a motor and a centrifugal fan and has a wall surface and an exhaust port on the radially outer side of the centrifugal fan, the wall having an opening through which cooling air flows, Provided is a power tool characterized by being provided in a biased state so as to be separated from a wall surface.

According to such a configuration, since the opening is provided in a state of being biased away from the wall surface, after the cooling air heated by the heat of the motor is discharged radially outward by the rotation of the centrifugal fan Even when it collides with the wall surface and returns to the centrifugal fan side, it is possible to suppress backflow to the motor side. Therefore, the amount of cooling air flowing back to the motor side is reduced, and the cooling efficiency of the motor can be improved. Further, by reducing the amount of cooling air that flows back to the motor side, a larger amount of cooling air is sent to the motor. Therefore, the cooling efficiency of the motor can be improved without significantly reducing the amount of cooling air that cools the motor.

The present invention further includes a motor having a rotation shaft, a centrifugal fan that rotates by rotation of the rotation shaft, a fan guide that guides a flow of cooling air generated by rotation of the centrifugal fan, a motor, a centrifugal fan, and a fan guide. A fan guide, and the fan guide has a base portion arranged radially outward of the centrifugal fan and an extending portion extending radially inward from the base so as to face the centrifugal fan in the axial direction of the rotating shaft. The extending portion has a first facing portion located in the first region where the radially outer side is open, and a second facing portion located in the second region where the radially outer side is the wall surface of the housing, The second facing portion provides a power tool characterized by being formed longer in the radial direction than the first facing portion.

According to such a configuration, the second facing portion of the extending portion of the fan guide is formed to have a length in the radial direction longer than that of the first facing portion, so that the cooling air heated by the heat of the motor is centrifuged. Even when the air is discharged radially outward by the rotation of the fan and then collides with the wall surface of the housing and returns to the centrifugal fan side, it is possible to suppress backflow to the motor side. Therefore, since the amount of cooling air that flows back to the motor side is reduced by the second facing portion, the cooling efficiency of the motor can be improved. Further, by reducing the amount of cooling air that flows back to the motor side, a larger amount of cooling air is sent to the motor. Therefore, the cooling efficiency of the motor can be improved without significantly reducing the amount of cooling air that cools the motor.

Moreover, since the length in the radial direction is shorter than that of the second opposing portion in the first facing portion, the cooling air can be smoothly guided from the motor side to the opening that exists radially outward of the centrifugal fan. Is possible. Therefore, a sufficient amount of cooling air can be secured, and the motor can be more efficiently cooled.

According to the electric tool of the present invention, the backflow of cooling air to the motor side can be effectively reduced, and the motor can be efficiently cooled.

It is an external view of the electric drill which is an example of the electric tool concerning this Embodiment. It is explanatory drawing which shows partially the internal structure of the electric drill concerning this Embodiment. It is the disassembled perspective view which showed the structure of the electric drill concerning this Embodiment. (A) is a perspective view which shows the fan concerning this Embodiment and its periphery structure, (b) is a top view explaining the relationship between the fan concerning this Embodiment, and its periphery structure, (c) FIG. 4 is a perspective view for explaining the relationship between the fan guide and its peripheral structure when the fan guide according to the present embodiment is attached to the fan. It is a sectional side view showing the state where the fan and fan guide concerning an embodiment of the invention are arranged in a housing. It is explanatory drawing which shows the flow of the cooling air at the time of using the fan guide which has a 2nd coating | coated part concerning this Embodiment. (A) is a top view of the fan guide concerning a comparative example, (b) is a sectional side view which shows the state by which the fan guide concerning a comparative example is arrange | positioned in the housing. It is explanatory drawing which shows the flow of the cooling air at the time of using the fan guide concerning the comparative example which does not have the 2nd coating | coated part concerning this Embodiment. (A) is a sectional side view which shows the shape of the fan blade | wing concerning the 1st modification of this Embodiment, (b) is the shape of the blade | wing of the fan concerning the 2nd modification of this Embodiment. FIG.

An electric drill 1 that is an example of an electric power tool according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

In the following description, “front” indicated by an arrow in FIG. 1 is defined as a front direction, “rear” is defined as a rear direction, “up” is defined as an upward direction, and “down” is defined as a downward direction. Further, when the electric drill 1 is viewed from behind, the left is defined as the left direction and the right is defined as the right direction.

First, the configuration of the electric drill 1 will be described with reference to FIGS. The electric drill 1 is an electric tool that performs a drilling operation on a work material.

As shown in FIGS. 1 and 2, the electric drill 1 includes a housing 2 that forms an outline thereof. The housing 2 includes a first housing 2A that constitutes a front end portion thereof and a second housing 2B that constitutes a rear portion thereof.

The first housing 2A has a substantially cylindrical shape extending in the front-rear direction, and an output portion 23 is provided at the front end thereof. A drill blade not shown as a tip tool can be detachably attached to the output unit 23. The second housing 2B extends downward from the rear portion of the first housing 2A, and a handle 21 for an operator to hold is formed at a lower end portion of the second housing 2B. A trigger switch 22 is provided at the front portion of the handle 21 and serves as an operator's operation location. The electric drill 1 is configured to receive power from the AC power source by being connected to an AC power source (commercial power source) (not shown).

In the housing 2, a motor 3 as a drive source, a fan 4, a fan guide 5, and a drive transmission unit 6 are accommodated.

The motor 3 is disposed at a substantially central portion in the housing 2. An annular space is provided between the motor 3 and the housing 2. The motor 3 is electrically connected to the trigger switch 22, and the rotation of the motor 3 is controlled according to an operation performed by the operator on the trigger switch 22.

As shown in FIG. 3, the motor 3 mainly includes a rotating shaft 31, a rotor (amateur) 32, a stator 33, and a commutator 36. The rotating shaft 31 is disposed so as to extend in the front-rear direction, and both ends in the front-rear direction are rotatably supported by the housing 2 via

bearings

34 and 35. More specifically, the front end portion of the rotating shaft 31 is rotatably supported by the first housing 2A via a bearing 34, and the rear end portion of the rotating shaft 31 is rotatably supported by the second housing 2B via a bearing 35. . The rotor 32 is a rotor that is provided on the rotating shaft 31 and rotates together with the rotating shaft 31. The rotor 32 is disposed so as to penetrate the inside of a substantially cylindrical stator 33 that is a stator in the front-rear direction. And have an amateur coil. The commutator 36 is provided to supply power to the amateur coil of the rotor 32. Since the configuration of the motor 3 is well known, detailed description thereof is omitted here. The rotating shaft 31 is an example of the “rotating shaft” in the present invention. In the following description, the rotor 32, the stator 33, and the commutator 36 may be collectively referred to as “the main body of the motor 3”.

The fan 4 is fixed to the front end portion of the rotating shaft 31. The fan 4 is configured to rotate together with the rotating shaft 31 of the motor 3, and generates cooling air for cooling the motor 3 by rotating. In the present embodiment, the fan 4 is a centrifugal fan, and is configured to discharge the cooling air radially outward by rotating. The fan 4 is an example of the “impeller” of the present invention and an example of a “centrifugal fan”.

The fan guide 5 is a member arranged to adjust the flow of cooling air generated by the rotation of the fan 4 and has a substantially annular shape in plan view as shown in FIG. That is, an opening 54 C (described later) is formed at a substantially central portion of the fan guide 5. The rotating shaft 31 to which the rotor 32 and the commutator 36 are fixed is inserted from behind the fan guide 5 so as to pass through the opening 54 C of the fan guide 5. The fan guide 5 is fixed to the housing 2 by being sandwiched between the first housing 2A and the second housing 2B. Detailed structures of the fan 4 and the fan guide 5 will be described later.

The drive transmission unit 6 is a mechanism for shifting (decelerating) the rotational force of the rotation shaft 31 of the motor 3 and transmitting it to the output unit 23. The drive transmission unit 6 is accommodated in the first housing 2 A and mainly includes a gear 61, a pinion gear 62, and an output shaft 63. The gear 61 is coaxially fixed to the output shaft 63. The pinion gear 62 is fixed to the front end portion of the rotating shaft 31 of the motor 3 and meshes with the gear 61. The output shaft 63 is disposed so that the axial direction thereof coincides with the front-rear direction, and is supported so as to be rotatable relative to the first housing 2 A via

bearings

64 and 65. The output portion 23 is fixed to the front end portion of the output shaft 63 so as not to be relatively rotatable. Accordingly, the output unit 23 is configured to rotate together with the output shaft 63 upon receiving the transmission of the rotational force of the rotary shaft 31. A drilling blade (not shown) attached to the output unit 23 rotates according to the rotation of the output unit 23, so that a drilling operation is performed on the work material.

Further, the housing 2 is formed with a pair of left and right intake ports 24 and a plurality of exhaust ports 25.

Each intake port 24 is a set of a plurality of slit-shaped through holes 24a, and is formed at the rear part of each of the left and right side walls of the second housing 2B. The plurality of exhaust ports 25 are through holes defined by a notch 26 formed at the rear edge of the first housing 2A and the front edge of the second housing 2B. That is, the intake port 24 and the exhaust port 25 are formed at different positions in the axial direction of the rotating shaft 31. Further, a part of the motor 3, in particular, the stator 33 and the commutator 36 that are heating elements, and the rotor 32 that penetrates the stator 33 are disposed between the intake port 24 and the exhaust port 25 in the axial direction of the rotating shaft 31. Be placed. The exhaust port 25 is an example of the “exhaust port” in the present invention, and is an example of the “opening”.

In the present embodiment, as shown in FIG. 3, a fan accommodating portion 27 for accommodating the fan 4 is formed at the rear end portion of the first housing 2A. The fan accommodating portion 27 has a circular shape in rear view, and is a concave portion that is recessed forward from the rear surface of the first housing 2A. The inner diameter of the fan accommodating portion 27 is formed slightly larger than the outer diameter of the fan 4. Specifically, the fan accommodating portion 27 includes a rear bottom circular surface 27 A that faces a fan main body 41 (described later) of the accommodated fan 4 in the front-rear direction, and a blade 42 of the fan 4 that is located on the radially outer side of the fan 4. This is defined by an outer peripheral portion (described later) and an annular peripheral wall surface 27B facing the rear view. A portion of the rear surface of the first housing 2 A located above the fan housing portion 27 functions as a proximity surface 28 that is close to a protrusion 52 (described later) of the fan guide 5.

The notch 26 is formed in the peripheral wall surface 27 B of the fan housing portion 27. Specifically, the notch 26 includes four

notches

26L, 26R, 26LD, and 26RD that are arranged in the circumferential direction of the fan accommodating portion 27 (the extending direction of the peripheral wall surface 27B). The

cutouts

26L and 26R open toward the left and right, respectively, and are arranged so as to be substantially opposed to each other in the left-right direction. The notches 26LD and 26RD are opened toward the lower left and the lower right, respectively. In a state where the first housing 2A and the second housing 2B are assembled (housing 2), as shown in FIGS. 1 and 2, each notch 26 and the front edge of the second housing 2B are defined. Each exhaust port 25 is disposed so as to substantially face the outer peripheral portion of the fan 4. That is, the exhaust port 25 is disposed radially outward of the fan 4 and is formed at substantially the same position as the fan 4 in the front-rear direction. Further, the portion where the exhaust port 25 (notch 26) is not formed in the peripheral wall surface 27 B is a portion which is disposed radially outward of the fan 4 and where the exhaust port 25 is not formed in the front-rear direction. The portion (region R1 to be described later) where the exhaust port 25 (notch 26) is formed in the peripheral wall surface 27B is an example of the “second wall portion” in the present invention, and “first portion” and “first region”. It is an example. Further, the portion of the peripheral wall surface 27B where the notch 26 is not formed (region R2 described later) is an example of the “second wall portion” in the present invention, and is an example of the “second portion” and the “second region”. It is.

As shown in FIG. 3, at the rear end portion of the first housing 2A having the fan accommodating portion 27, the screw boss A1 is provided below the peripheral wall surface 27B connecting the notch 26LD and the notch 26RD. Screw bosses A2 and A3 are respectively provided on the upper left and upper right of the peripheral wall surface 27B connecting 26L and the notch 26R. The first housing 2A and the second housing 2B are fixed to each other by being screwed by screws inserted through the screw bosses A1, A2, and A3, thereby forming the housing 2. In FIG. 2, only the screw inserted through the screw boss A1 is shown.

Next, the fan 4 and the fan guide 5 according to the present embodiment will be described in detail.

As shown in FIG. 2, the fan 4 is housed in the fan housing portion 27 of the first housing 2 A in the housing 2. As shown in FIGS. 3 and 5, the fan 4 integrally includes a fan main body 41 and a plurality of blades 42. The fan main body 41 has a disk shape, and is fixed to the rotating shaft 31 of the motor 3 at the center thereof. The plurality of blades 42 are erected on the rear surface of the fan body 41 in a radial manner around the rotation shaft 31. That is, the plurality of blades 42 are arranged at predetermined intervals (equal intervals) along the circumferential direction of the fan body 41. In the present embodiment, as shown in FIG. 5, each blade 42 has a substantially trapezoidal shape in side view. That is, each blade 42 has a radially outer vertex 42A and a radially inner vertex 42B.

As schematically shown in FIGS. 4 (a) and 4 (b), in the state of being accommodated in the fan accommodating portion 27, the outer peripheral portion of the blade 42 of the fan 4 is the exhaust port 25 in the radial direction of the fan 4. It is substantially opposite to (notch 26). In FIG. 4, for convenience of explanation, the exhaust ports 25 are illustrated as being provided one each on the left and right. That is, the notches 26L and 26LD are collectively shown as 26L, and 26R and 26RD are collectively shown as 26R.

In the housing 2, the fan guide 5 is disposed between the blades 42 of the fan 4 and the rotor 32 of the motor 3 in the front-rear direction (the axial direction of the rotation shaft 31).

As shown in FIGS. 3 and 5, the fan guide 5 integrally includes a base portion 51, a protruding portion 52, a pair of support portions 53, and a covering portion 54. Further, an opening 54 C is formed in a substantially central portion of the covering portion 54. The opening 54C is an example of the “opening” in the present invention.

The base 51 has a substantially annular shape so as to surround the outer peripheral portion of the blade 42 of the fan 4. The inner diameter of the base portion 51 is substantially the same as the inner diameter of the peripheral wall surface 27 B that defines the fan housing portion 27. That is, as shown in FIG. 5, in a state where the fan guide 5 is mounted on the housing 2, the base 51 is provided on the radially outer side of the fan 4 with respect to the outer peripheral portion of the blade 42 of the fan 4. Opposite the outer periphery of the blade 42. Further, in a state where the fan guide 5 is mounted on the housing 2, at least a part of the inner peripheral surface of the base portion 51 and the peripheral wall surface 27 B are disposed so as to substantially face the outer peripheral portion of the blade 42 of the fan 4. The base 51 constitutes a part of the “second wall” of the present invention together with the peripheral wall surface 27B. The base 51 is also an example of the “base” in the present invention.

The protruding portion 52 protrudes upward from the upper end portion of the outer peripheral surface of the base portion 51 and has a substantially flat plate shape. As shown in FIGS. 3 and 5, the protrusion 52 is close to the proximity surface 28 of the rear end portion of the first housing 2 A on its front surface and is close to the front edge of the second housing 2 B on its rear surface. The pair of support portions 53 are provided so as to protrude rearward from the upper end portion and the lower end portion on the rear surface of the base portion 51. A stator 33 of the motor 3 is inserted between the support portions 53. The support portion 53 contacts the upper and lower portions of the front end surface of the stator 33, so that the stator 33 is positioned in the front-rear direction and the vertical direction.

The covering portion 54 is a portion extending from the base portion 51 toward the inside in the radial direction of the fan 4 and has a substantially annular shape in rear view (see FIG. 4C). As shown in FIGS. 2 and 5, the covering portion 54 faces the rotor 32 of the motor 3 in the front-rear direction, that is, faces the rear surface of the fan 4 (the surface on the side facing the rotor 32) in the front-rear direction. Are arranged as follows. The covering portion 54 extends inward in the radial direction of the fan 4 from the base portion 51 along the outline of the blade 42 of the fan 4. That is, the covering portion 54 is disposed inside the peripheral wall surface 27 B and the base portion 51 in the radial direction of the fan 4. The covering portion 54 is disposed at a position close to the blade 42 with a slight gap between the cover portion 54 and the blade 42 in the front-rear direction. The covering portion 54 is an example of the “first wall portion” in the present invention, and is an example of the “wall portion” and the “extending portion”.

Specifically, the covering portion 54 integrally includes a first covering portion 54A and a second covering portion 54B. The first covering portion 54A is an example of the “first facing portion” in the present invention, and the second covering portion 54B is an example of the “second facing portion” in the present invention.

54 A of 1st coating | coated parts are the parts which comprise the lower part of the coating | coated part 54, and are arrange | positioned so that the exhaust port 25 may be opposed in the front-back direction. More specifically, as shown in FIG. 4C, the first covering portion 54 A substantially opposes the region R 1 in which the notches 26 L and 26 R are formed in the peripheral wall surface 27 B of the fan housing portion 27 in the front-rear direction. Are arranged as follows. In the present embodiment, as shown in FIG. 5, the first covering portion 54 A is in the vicinity of the apex 42 A on the radially outer side of each blade 42 of the fan 4 in the state of being arranged in the fan accommodating portion 27. It extends to.

The second covering portion 54B is a portion constituting the upper portion of the covering portion 54, and is disposed so as to face the portion of the peripheral wall surface 27B of the fan accommodating portion 27 where the exhaust port 25 is not formed in the front-rear direction. More specifically, as shown in FIG. 4, the second covering portion 54 B is substantially opposed to the region R 2 where the notches 26 L and 26 R are not formed in the peripheral wall surface 27 B of the fan housing portion 27 in the front-rear direction. Be placed. In the present embodiment, as shown in FIG. 5, the second covering portion 54 B is substantially the same as the apex 42 B on the radially inner side of the blade 42 of the fan 4 in the state of being arranged in the fan accommodating portion 27. It is configured to extend to the same position or a radially inner position from the apex 42B. That is, as shown in FIGS. 3 and 4C, the length of the second covering portion 54 B in the radial direction of the fan 4 is longer than the length of the first covering portion 54 A in the radial direction of the fan 4. It is configured.

That is, in the fan guide 5 according to the present embodiment, in the housing 2, the second covering portion 54B is radially inward from the region R2 of the peripheral wall surface 27B of the fan accommodating portion 27, and the first covering portion 54A is circumferential. The wall 27 B is provided so as to be disposed radially inward from the region R 1 where the exhaust port 25 (notches 26 L and 26 R) is formed. In other words, the opening 54 C has an asymmetric shape with respect to the center (axial center) of the rotation shaft 31. Specifically, the opening 54C has a distance from the center of the rotation shaft 31 in the vicinity where the exhaust port 25 is provided to the inner peripheral surface of the opening 54C (the inner end surface of the first covering portion 54A), and the peripheral wall surface 27B. Is formed on the covering portion 54 so as to be shorter than the distance from the center of the rotating shaft 31 in the vicinity where the opening is provided to the inner peripheral surface of the opening portion 54C (the inner end surface of the second covering portion 54B). That is, the opening 54C is separated from the circumferential wall surface 27B (the upper region R2 in FIG. 4C) that is long in the circumferential direction in FIG. 4C in the radial direction of the rotating shaft 31, and in the circumferential direction in FIG. It is provided in a state of being biased toward the short peripheral wall surface 27B (lower region R2 in the figure). In other words, the opening 54C is separated from the circumferential wall surface 27B (the upper region R2 in FIG. 4C) that is long in the circumferential direction in FIG. 4C in the covering portion 54 and in the circumferential direction in FIG. It is formed at a position close to the short peripheral wall surface 27B (lower region R2 in the figure).

Next, the flow of cooling air in the electric drill 1 provided with the fan guide 5 according to the present invention will be described with reference to FIG. As a comparative example, FIG. 8 shows the flow of cooling air in an electric drill when a fan guide 500 having a shape different from that of the fan guide 5 according to the present invention is provided. For convenience of explanation, in FIGS. 6 and 8, the screw boss A1 formed below the peripheral wall surface 27B of the fan housing portion 27 is omitted, and the exhaust port 25 is formed. 6 and 8, illustration of the support portion 53 of the fan guide 5 is also omitted.

When the fan 4 fixed to the rotating shaft 31 is rotated along with the rotation of the rotating shaft 31 of the motor 3, outside air is introduced into the housing 2 from the air inlet 24. The air taken into the housing 2 cools the main body of the motor 3 while passing forward through the space formed between the main body of the motor 3 and the housing 2 as the fan 4 rotates. The gas is discharged from the exhaust port 25 to the outside of the housing 2. Specifically, the outside air taken in from the air inlet 24 is formed between the radially inner portion of the fan 4 (the vicinity of the rotating shaft 31) and the covering portion 54 of the fan guide 5 after cooling the main body of the motor 3. After passing through the gap (air path), the air passes through the adjacent blades 42 of the fan 4 and is finally discharged out of the housing 2 radially from the exhaust port 25 toward the outside in the radial direction of the fan 4.

The cooling air after cooling the main body of the motor 3 is warmed by heat generated by the main body of the motor 3 (particularly, the stator 33 (stator coil), the amateur coil and the commutator 36). Therefore, once the warmed cooling air is once exhausted by the fan 4 and flows again to the main body side of the motor 3, the cooling of the main body of the motor 3 is hindered. Further, when the warmed cooling air flows backward to the main body side of the motor 3, the amount of outside air (suction amount) to be newly taken into the housing 2 through the intake port 24 for cooling the main body of the motor 3 is reduced. Will end up. That is, the amount of cooling air that contributes to the cooling of the main body of the motor 3 is reduced, and the cooling efficiency of the main body of the motor 3 is reduced. Therefore, the amount of cooling air that flows back to the main body side of the motor 3 is smaller. Is preferred.

The fan 4 which is a centrifugal fan discharges the cooling air after cooling the main body of the motor 3 to the outside in the radial direction. Therefore, if there is a wall surface facing the outer peripheral portion of the blade 42 of the fan 4 on the radially outer side of the fan 4, the discharged cooling air flows so as to collide with the wall surface and return to the fan 4 side, and then the fan guide. 5 may flow backward so as to return to the main body side of the motor 3 beyond the covering portion 54 of the motor 5. That is, in the present embodiment, the backflow of the cooling air after cooling the main body of the motor 3 tends to occur in the region R2 of the peripheral wall surface 27B where the exhaust port 25 is not formed.

Therefore, in the fan guide 5 according to the present embodiment, as shown in FIG. 4C, the second covering portion 54 B is disposed at a position facing the region R 2 where backflow is likely to occur in the front-rear direction. .

As described above, the second covering portion 54B provided corresponding to the region R2 is longer in the radial direction than the first covering portion 54A. Therefore, as indicated by an arrow W2 in FIG. 6, the second covering portion 54B acts to block the flow of cooling air that tends to flow backward to the motor 3 side beyond the fan guide 5. Specifically, the second covering portion 54 B collides with the peripheral wall surface 27 B after being discharged from the fan 4, passes between adjacent blades 42 of the fan 4, and the covering portion 54 of the fan guide 5 and the fan 4. The flow of the cooling air that tends to flow backward toward the rotor 32 of the motor 3 can be blocked through a gap (air passage) formed between the inner portion in the radial direction (portion in the vicinity of the rotary shaft 31).

Here, as a comparative example, a fan guide 500 having a shape different from that of the fan guide 5 according to the present invention is assumed. The fan guide 500 does not include the second covering portion 54B according to the present embodiment. That is, as illustrated in FIG. 7A, in the fan guide 500, it is assumed that only the first covering portion 54A is provided in an annular shape as viewed from the rear as the covering portion 54. In this case, the first covering portion 54A whose radial length is shorter than the second covering portion 54B faces not only the region R1 but also the region R2 in the front-rear direction. Therefore, as illustrated in FIG. 7B, the first covering portion 54A extends only to the vicinity of the apex 42A near the radially outer side of the blade 42 of the fan 4 in the region R2. Therefore, as indicated by an arrow W3 in FIG. 8, the cooling air discharged from the fan 4 and colliding with the peripheral wall surface 27B after cooling the main body of the motor 3 (that is, the cooling air discharged from the fan 4 in the region R2) After flowing back to the fan 4, it further flows back beyond the first covering portion 54 A to the main body side of the motor 3. As described above, in the first covering portion 54A having a shorter radial direction than the second covering portion 54B, it is difficult to sufficiently block the cooling air from the fan 4 to return further to the main body side of the motor 3. The backflow of the cooling air to the main body side cannot be sufficiently prevented.

In contrast, in the present embodiment, as shown in FIG. 6, the second covering portion 54 B having a long length in the radial direction of the fan 4 is disposed at a position facing the region R 2 where backflow is likely to occur. The Therefore, after the cooling air heated by the heat generated from the main body of the motor 3 is discharged radially outward by the rotation of the fan 4 by the second covering portion 54B, it collides with the peripheral wall surface 27B and returns to the fan 4 side. Even in the case of backlash, the backflow to the main body side of the motor 3 is suppressed. Since the amount of cooling air that flows back to the main body side of the motor 3 can be reduced by the second covering portion 54B, the cooling efficiency of the main body of the motor 3 can be improved. Further, by reducing the amount of cooling air that flows back to the main body side of the motor 3, it becomes possible to newly take in more outside air into the housing 2 through the intake port 24. That is, it is possible to newly send a large amount of cooling air toward the main body of the motor 3 by the amount by which the amount of backflow decreases. Therefore, the cooling efficiency of the main body of the motor 3 can be improved without significantly reducing the amount of cooling air that cools the main body of the motor 3.

In the region R1 where the exhaust port 25 exists, the cooling air discharged to the outer side in the radial direction of the fan 4 is discharged from the exhaust port 25 facing the outer peripheral portion of the blade 42, and thus backflow hardly occurs. Therefore, in the present embodiment, the first covering portion 54A having a length in the radial direction shorter than the second covering portion 54B is arranged at a position facing the region R1 in the front-rear direction. Therefore, as indicated by an arrow W1 in FIG. 6, in the region R1, most of the cooling air discharged from the fan 4 to the outside in the radial direction smoothly out of the housing 2 through the exhaust port 25. Discharged. As described above, in the region R1, the first covering portion 54A cools from the main body side of the motor 3 to the exhaust port 25 formed radially outward of the fan 4 while suppressing the backflow of the cooling air to the minimum. It is possible to guide the wind smoothly. Therefore, a sufficient amount of cooling air can be ensured, and the main body of the motor 3 can be more efficiently cooled.

Further, according to such a configuration, the second covering portion 54 B is configured as a part of the fan guide 5. That is, simply by making the radial length of the second covering portion 54B of the fan guide 5 facing the region R2 longer than the radial length of the first covering portion 54A facing the region R1, It is possible to effectively suppress the backflow of the cooling air. Further, since it is not necessary to change the configuration other than the fan guide 5, the manufacturing cost of the electric drill 1 can be suppressed and the manufacturing process can be prevented from becoming complicated.

In the present embodiment, the peripheral wall surface 27B is configured as a part of the housing 2 (first housing 2A). Therefore, compared with the case where the peripheral wall surface 27B and the housing 2 are configured separately, the number of parts necessary for manufacturing the electric drill 1 can be reduced, and the manufacturing cost can be suppressed and the assemblability can be improved. it can. *

Further, in the present embodiment, at least a part of the main body of the motor 3 (the rotor 32, the stator 33, the commutator) between the intake port 24 and the exhaust port 25 in the axial direction (front-rear direction) of the rotating shaft 31 of the motor 3. 36) is arranged. That is, the stator 33 and the commutator 36 that are heating elements and the rotor 32 are arranged on the flow path through which the cooling air flows from the intake port 24 to the exhaust port 25. Therefore, the rotor 32, the stator 33, and the commutator 36 can be efficiently cooled.

The work tool according to the present invention is not limited to the above-described embodiment and the like, and various modifications are possible within the scope of the gist of the invention described in the claims, for example.

For example, in the embodiment described above, the first covering portion 54A extends to the vicinity of the vertex 42A on the radially outer side of each blade 42, and the second covering portion 54B extends to the vicinity of the vertex 42B on the radially inner side of each blade 42. However, the present invention is not limited to this. The fan guide 5 may be configured such that the radial length of the second covering portion 54B is longer than the radial length of the first covering portion 54A. In addition, the lengths of the first covering portion 54A and the second covering portion 54B can be changed according to the size of the gap between the covering portion 54 and the blades 42. Specifically, when the distance from the blade 42 is increased, in order to sufficiently prevent backflow, it is necessary to increase the radial length of the first covering portion 54A and the second covering portion 54B. When the distance from is shortened, the radial lengths of the first covering portion 54A and the second covering portion 54B can be shortened.

In the embodiment and the above-described embodiment, the blades 42 of the fan 4 have a substantially trapezoidal shape when viewed from the side. However, the shape of the blades of the centrifugal fan of the present invention is not limited to a trapezoid.

FIG. 9A shows a centrifugal fan 140 having blades 142 having a substantially triangular side view as a first modification of the above-described embodiment. In this case, the fan guide 150 provided corresponding to the centrifugal fan 140 has a first covering portion 154A and a second covering portion 154B, and the second covering portion 154B has a length in the radial direction longer than that of the first covering portion 154A. It is structured long. In the fan guide 150, the first covering portion 154A is disposed radially inward of the portion (first portion) where the outer peripheral portion of the blade 142 of the centrifugal fan 140 is opposed to the exhaust port 25, and the outer peripheral portion of the blade 142 is opposed to the peripheral wall surface 27B. What is necessary is just to provide so that the 2nd coating | coated part 154B may be arrange | positioned inside the radial direction of the part (2nd part) to do. In this case, it is desirable that the second covering portion 154B extends from the base portion 51 to the inside in the radial direction of the fan guide 150 up to a position beyond the apex of the blade 142.

Moreover, FIG.9 (b) has shown the centrifugal fan 240 which has the blade | wing 242 of a side view substantially rectangular shape as the 2nd modification of the above-mentioned embodiment. In this case, the fan guide 250 provided corresponding to the centrifugal fan 240 has a first covering portion 254A and a second covering portion 254B, and the second covering portion 254B is longer in the radial direction than the first covering portion 254A. Is structured long. In the fan guide 250, the first covering portion 254A is disposed radially inward of the portion (first portion) where the outer peripheral portion of the blade 242 of the centrifugal fan 240 faces the exhaust port 25, and the outer peripheral portion of the blade 242 faces the peripheral wall surface 27B. What is necessary is just to provide so that the 2nd coating | coated part 254B may be arrange | positioned inside the radial direction of the part (2nd part) to perform. In this case, it is desirable that the second covering portion 254B extends from the base 51 to the inside in the radial direction of the fan guide 250 to a position beyond the vicinity of the central portion in the radial direction of the blade 242.

In the above-described embodiment, the fan guide 5 is configured as a separate body from the housing 2, but the fan guide 5 and the housing 2 may be configured integrally. For example, when the housing is composed of two left and right portions, the fan guide may be configured by assembling the left and right portions of the housing.

In the above-described embodiment, the electric drill 1 has been described as an example of the electric tool. However, the electric tool according to the present invention is not limited to the electric drill, and besides the electric drill, a fan guide is provided in the centrifugal fan for cooling the motor. It is applicable to the electric tool to be attached.

In the above-described embodiment, the output unit 23 is configured to be mounted with a drill blade as a tip tool. However, the tip tool mounted on the output unit 23 is not limited to a drill blade, and for example, A driver bit for tightening the screw member may be used, or a drill bit for drilling or crushing concrete, stone, or the like may be used.

DESCRIPTION OF SYMBOLS 1 ... Electric drill, 2 ... Housing, 3 ... Motor, 4 ... Fan, 5 ... Fan guide, 6 ... Drive transmission part, 24 ... Intake port, 25 ... Exhaust port, 26 ... Notch, 27 ... Fan accommodating part, 27B ... peripheral wall, 31 ... rotating shaft, 32 ... rotor, 33 ... stator, 36 ... commutator, 42 ... vane, 51 ... base, 54 ... covering portion, 54A ... first covering portion, 54B ... second covering portion, 54C ... Aperture

Claims

A motor having a rotating shaft;
A centrifugal fan having an impeller rotated by rotation of the rotating shaft;
A first wall portion that has an annular shape and faces the motor side surface of the impeller in the axial direction of the rotating shaft;
A second wall portion provided on a radially outer side of the impeller and extending in the axial direction so as to face an outer peripheral portion of the impeller,
The second wall portion includes a first portion in which an exhaust port facing the outer peripheral portion is formed, and a second portion in which a wall surface facing the outer peripheral portion exists,
The first wall portion includes a first facing portion disposed on the radially inner side of the first portion, and a second facing portion disposed on the radially inner side of the second portion,
The length of the said 2nd opposing part of the said radial direction is longer than the radial length of the said 1st opposing part, The electric tool characterized by the above-mentioned.
The electric power tool according to claim 1, wherein the first wall portion constitutes a part of a fan guide that guides a flow of cooling air generated by rotation of the impeller.
The electric power tool according to claim 1, wherein the second wall portion constitutes a part of a housing that houses the motor and the centrifugal fan.
The housing has an intake port formed at a position different from the exhaust port in the axial direction, and at least a part of the motor is disposed between the intake port and the exhaust port in the axial direction. The power tool according to claim 3, wherein the power tool is a power tool.
A motor having a rotating shaft;
A centrifugal fan that rotates by rotation of the rotating shaft;
A wall portion extending in the radial direction of the rotary shaft between the centrifugal fan and the motor in the axial direction of the rotary shaft so as to guide the flow of cooling air generated by the rotation of the centrifugal fan;
A housing that houses the motor and the centrifugal fan, and that has a wall surface and an exhaust port on a radially outer side of the centrifugal fan;
The wall has an opening through which the cooling air flows,
The distance from the center of the rotating shaft in the vicinity of the wall surface to the inner peripheral surface of the opening is shorter than the distance from the center of the rotating shaft in the vicinity of the exhaust port to the inner peripheral surface of the opening. An electric tool characterized by that.
A motor having a rotating shaft;
A centrifugal fan that rotates by rotation of the rotating shaft;
A wall portion facing the centrifugal fan and the motor in the axial direction of the rotating shaft so as to guide a flow of cooling air generated by the rotation of the centrifugal fan;
A housing that houses the motor and the centrifugal fan, and that has a wall surface and an exhaust port on a radially outer side of the centrifugal fan;
The wall has an opening through which the cooling air flows,
The opening is provided in a state of being biased away from the wall surface.
A motor having a rotating shaft;
A centrifugal fan that rotates by rotation of the rotating shaft;
A fan guide for guiding the flow of cooling air generated by the rotation of the centrifugal fan;
A housing for housing the motor, the centrifugal fan, and the fan guide;
The fan guide has a base portion arranged on the radially outer side of the centrifugal fan, and an extending portion extending from the base portion to the radially inner side so as to face the centrifugal fan in the axial direction of the rotating shaft. And
The extending portion has a first facing portion located in a first region where the radially outer side is open, and a second facing portion located in a second region where the radially outer side is a wall surface of the housing. And
The power tool, wherein the second facing portion is formed longer in the radial direction than the first facing portion.