JP2002103251A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool reducing noise caused by an air current from an impeller. SOLUTION: A motor and the impeller mounted on a rotating shaft of the motor are provided inside a casing, a tool body is connected to the rotating shaft of the motor and the tool body is driven by the motor on the power tool such as a grinder etc., and it is devised to cool the motor by generating a high speed air current in the circumference of the motor by rotating the impeller by the motor. A channel on the fan discharge side is extended and molded in a large channel 14 on such the power tool. Four pieces of scroll outlets and two pieces of upper and lower discharge ports 24 provided in a gear cover 5b are respectively communicated to each other, namely the two scroll outlets to the two scroll outlets and the one discharge port to the one discharge port by a guide plate 11, a guide plate 12 for air discharge is attached to an end part of the discharge port in the gear cover 5b, and an air discharge port 13 is provided on a head end part of the gear cover 5b. Additionally, the high speed air current from the impeller 4 is discharged outside after reducing the speed by a scroll 21 and a scroll 21a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power tool such as a grinder, and more particularly to a power tool in which an impeller is mounted on a rotating shaft of a motor, and the impeller rotates to cool the motor.

[0002]

2. Description of the Related Art Generally, an electric tool such as a grinder is provided with a motor and a tool connected to a rotating shaft of the motor, and the motor is used to drive the tool to process a workpiece. Also, an impeller is attached to the rotating shaft of the motor,
The impeller is also rotated by the motor at the same time that the tool is rotationally driven, whereby an air flow is generated around the motor to cool the motor. Although the motor and impeller are housed in a box-shaped casing, there is only a space on the fan discharge side, and the number of scroll outlets in the fan casing depends on the strength of the gear cover and side handles on both sides of the gear cover. Not only can it take two upper and lower parts because it is attached, but the correspondence of ventilation between each outlet of the multi-scroll and the discharge port in the gear cover is ambiguous. Furthermore, the air from the multi-scroll outlet circulates in the gear cover in the circumferential direction,
Some airflows flowed out of the discharge port, and other airflows that could not flow out of the discharge port flowed further downstream in the circumferential direction and flowed out of the next discharge port.

[0003]

However, according to the above-mentioned prior art, when the air accelerated by the impeller flows out of the casing to the outside, a loud noise is generated, and a person who operates the power tool and a surrounding area are operated. There is the problem of giving people discomfort. That is, in a conventional power tool. A plurality of holes are formed in the casing, and high-speed airflow from the impeller is discharged to the outside through the holes,
When the air passes through the holes, it generates loud noises, such as jet noise.

[0004] It is an object of the present invention to provide a power tool that reduces noise generated by airflow from an impeller.

[0005]

In order to achieve the above object, the present invention provides a motor having a motor and an impeller mounted on a rotating shaft of the motor, wherein the rotating shaft of the motor is provided inside the casing. A tool body is connected, and the tool body is driven by the motor, and the impeller is rotated by the motor, thereby generating a high-speed airflow around the motor to cool the motor. In the power tool, the flow path on the fan discharge side is formed into an enlarged flow path, and the distance between the scroll outlet in the case of four in the present invention in the fan casing and the upper and lower two discharge ports in the gear cover is 2 in each case.
A guide plate communicates with each scroll outlet and each discharge port, and an air discharge guide plate is provided at the end of the discharge port in the gear cover, while an air discharge port is provided at the tip of the gear cover to supply air. It is characterized by spills.

[0006] According to the above structure, the expanded flow path increases the static pressure of the flow and increases the air flow. Each outlet of the multi-scroll and the discharge port in the gear cover correspond to the flow. Since the amount of air flowing out of the gears is made uniform and the wind speed decreases, the ventilation resistance associated with discharge decreases, and the ventilation resistance in the gear cover decreases, thereby reducing the amount of fluid noise generated. Further, there is no needless flow circulating in the circumferential direction to the next discharge port without being able to flow out of the discharge port, so that the load on the fan is reduced and the fan noise is reduced. Furthermore, the air from the multi-scroll outlet is not allowed to flow directly from the adjacent outlet in the gear cover. If air flows out from the tip air discharge port provided at the tip of the gear cover after the air has made a half circle in the circumferential direction in the gear cover, noise can be reduced due to the sound insulation effect of the tip of the gear cover (metal plate). .

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a grinder as an electric tool according to the present invention. In FIG. 1, a grinder 1 has a motor 2 and an impeller 4 attached to a rotating shaft 3 of the motor 2.
Are housed in the motor cover 5a and the gear cover 5b. A bevel gear 6 is attached to the tip of the rotating shaft 3 of the motor 2, and this bevel gear 6 meshes with a bevel gear 7 attached to a rotating shaft 8 of a grindstone 9. Also, the gear cover 5b
Is formed with holes 10 for discharging airflow from the impeller 4, and side handles 15 are provided on both sides of the gear cover 5b.
Is attached.

In this embodiment, the multi-scroll 21
In order to make the respective outlets correspond to the discharge ports 24 in the gear cover 5b, the guide plates 11 communicate with each other, and an air discharge guide plate 12 is provided at the end of the discharge ports in the gear cover. Details of the guide plate 11 and the air discharge guide plate 12 are shown in FIGS.
This will be described with reference to FIG. FIG. 2 is a view taken along line AA of FIG. 1 and is a perspective view showing the scroll 21 and the partition wall 22 from which the impeller has been removed. FIG. 3 is also an arrow view along the line AA, showing the scroll 21, the impeller 4, and the flow of air from the impeller 4. FIG. 4 also shows AA
The scroll 21, the impeller 4, and the guide plate 11, the air discharge guide plate 12, and the discharge port 24 as viewed from the discharge side are indicated by broken lines in the arrow view along the line. FIG. 5 is FIG.
2 is a perspective view taken along line BB of FIG. 1, showing the guide plate 11, the air discharge guide plate 12, and the flow of air. FIG.
FIG. 2 is a perspective view of the grinder according to the present invention in which a side handle 15 is attached. FIG. 7 is a view taken in the direction of the arrows along the line CC in FIG.
The flow of air at the discharge port 24 and the discharge side is shown. FIG. 8 is a perspective view taken along the line D in FIG.
Is shown.

As shown in FIG. 2, FIG. 3 and FIG. 4, the scroll 2 has a surface facing the impeller 4 facing the outer periphery of the impeller 4.
4 are formed. Scroll 21 is impeller 4
The flow path is formed by an enlarged flow path 14 which is gradually expanded at a rate of about 3 degrees along the high-speed air flow a from the outside. In order to separate adjacent scrolls 21, a partition wall 22 is provided.
Is provided. In the figure, 4a is the impeller 4
B indicates the rotation direction of the impeller 4.

As shown in FIGS. 5 and 7, four scrolls 21a communicating with the scroll 21 are provided on the surface on the opposite side (discharge side) of the impeller 4, and the scroll further communicates with the scroll 21a. A discharge channel 23 is provided. Two discharge ports 24 are formed at two opposite ends of the discharge flow path 23 (upper and lower sides of the gear cover 5b). The reason why the discharge port 24 can be formed only at two locations above and below the gear cover 5b with respect to the number of outlets of the scroll 21a is that side handles 15 necessary for using a power tool are provided on both sides of the gear cover 5b. . When the airflow from the scrolls 21 and 22a is discharged to the discharge port 24, the scroll outlet and the discharge port are used to prevent a wasteful flow that cannot flow out of the discharge port and circulates in the circumferential direction to the next discharge port. One discharge port 24 on the side is communicated with the guide plate 11, and an air discharge guide plate 12 is attached to an end of the discharge port 24. Further, a discharge port 1 is provided at the tip of the gear cover 5b.
3 are provided.

When the motor 2 is rotated in the electric tool having the above configuration, the grindstone 9 is driven to rotate via the rotating shaft 3, bevel gears 6 and 7, and the rotating shaft 8. At the same time, the impeller 4 is driven to rotate, and the external air flows into the motor cover 5a as shown in FIGS. 1c and 1d and flows through the motor cover 5a as shown in FIG. You. The air that has cooled the motor 2 passes through the impeller 4 as shown by f.
g, the air flows through the scroll 21, the enlarged flow path 14, the scroll 21 and the discharge flow path 23, passes through the inside of the gear cover 5b, and is provided with the air discharge port 13 provided at the tip end of the gear cover 5b.
Is discharged to the outside.

The air flow flowing from the impeller 4 into the scroll 21 is as high as 80 m / s, but the flow path of the scroll 21 is gradually enlarged along the air flow a.
Since it is set to 4, the inflowing air flow is decelerated when passing through the scroll 21. The scroll 21a is separated from the impeller 4 by the partition wall 22, but since the flow path is an extension of the scroll 21, the airflow is further decelerated when passing through the scroll 21a. The four scroll outlets and the upper and lower two discharge ports 24 on the discharge side communicate with each other between the two scroll outlets and the one discharge port 24 by the guide plate 11. Since the guide plate 12 is provided to make the flow of air correspond to the discharge ports, the amount of air flowing out from each discharge port is made uniform and the wind speed is reduced, so that the ventilation resistance accompanying discharge is reduced,
The ventilation resistance in the gear cover 5b is reduced, and the amount of fluid noise generated is reduced. Further, there is no needless flow such as being unable to flow out of the discharge port and circulating in the circumferential direction to the next discharge port, reducing the load on the fan and reducing the noise of the fan. According to the present embodiment, noise is reduced by about 4 dB as compared with the related art. The velocity energy of the air flow is converted into static pressure energy in the scrolls 21 and 21a, and at the exit of the scroll 21a, the air velocity becomes low at about 25 m / s. Further, the low-velocity airflow is rectified when passing through the discharge flow path 23, and is not directly discharged from the discharge port in the neighboring gear cover through the discharge port 24, but is not directly discharged from the gear cover 5b.
After half-circumferentially in the inside of the gear cover, it flows out from the discharge port in the gear cover, and is discharged to the outside through the discharge port 13 provided at the tip of the gear cover 5b.

According to the present embodiment, the impellers 4 to 80
The air flow that has flowed out at a high speed of m / s is gradually decelerated by the scroll 21 and the scroll 21a to a low speed of approximately 25 / s, and is reduced to approximately ３ of the flow speed at the exit of the impeller 4. The noise can be reduced, and the noise insulation effect of the gear cover 5b (metal plate) reduces the noise by 3 dB as compared with the case where the air does not make a half turn in the circumferential direction, and allows the air to flow out from the discharge port provided at the tip of the gear cover 5b. Accordingly, the noise is reduced by 3 dB due to the sound insulation effect of the distal end portion (metal plate) of the gear cover 5b.

In addition, as a whole, from the entrance of the scroll 21 to the exit of the scroll 21a, the static pressure of the air flow increases each time the air flow decelerates, so that the static pressure of the turbo fan increases. The intersection (operating point) between the turbo fan and the power tool ventilation system shifts to a large air volume region, the motor cooling air volume also increases, and the reliability of the motor of the power tool is greatly improved.

Although the above embodiment has been described with reference to a grinder, the present invention is not limited to a grinder and can be applied to an electric saw or the like.

[0016]

As described above, according to the present invention,
Since the flow path on the fan discharge side is formed as an enlarged flow path, the static pressure of the flow is improved and the air volume is increased. Also, by making the scroll outlet correspond to the discharge port in the gear cover, the amount of air flowing out of each discharge port is made uniform and the wind speed is reduced, so that the ventilation resistance associated with the discharge is small and the sound insulation of the gear cover 5b (metal plate). Due to the effect, the ventilation resistance in the gear cover is reduced, so that the amount of generated fluid noise is reduced, there is no useless flow of air, and the load on the fan is reduced, so that the fan noise is reduced. Furthermore, by allowing the airflow from the scroll outlet to flow out from the tip of the gear cover, noise can be reduced due to the sound insulation effect of the tip of the gear cover (metal plate).

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power tool according to the present invention.

FIG. 2 is a perspective view taken along line AA of FIG. 1;

FIG. 3 is an arrow view as viewed along the line AA in FIG. 1;

FIG. 4 is an arrow view as viewed along the line AA in FIG. 1;

FIG. 5 is a perspective view taken along the line BB of FIG. 1;

FIG. 6 is a perspective view of a power tool according to the present invention.

FIG. 7 is a view as viewed in the direction of arrows along the line CC in FIG. 1;

FIG. 8 is a perspective view taken along the line D in FIG. 1;

[Explanation of symbols]

1 is a grinder, 2 is a motor, 3 and 8 are rotary shafts, 4 is an impeller, 4a is a blade, 5a and 5b are covers, 6 and 7 are bevel gears, 9 is a grindstone (tool body), 10 is a hole, 11 Is a guide plate, 12 is a guide plate for air discharge, 13 and 24 are discharge ports,
15 is a side handle, 21 and 21a are scrolls, 2
2 is a partition wall and 23 discharge flow paths.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoya Ikeda 1060 Takeda, Hitachinaka-shi, Ibaraki F-term in Hitachi Koki Co., Ltd. (reference) 3C058 AA04 AA11 AA16 AC01 3L044 AA04 BA06 CA18 HA04 KA04

Claims (4)

[Claims] A motor and an impeller mounted on a rotating shaft of the motor are provided inside a casing, and a tool body is connected to the rotating shaft of the motor, and the tool body is driven by the motor. On the other hand, by rotating the impeller with the motor, a high-speed air flow is generated around the motor to cool the motor. A power tool characterized in that: 2. A power tool according to claim 1, wherein a guide plate communicates between the plurality of scroll outlets in the fan casing and one discharge port in the gear cover. 3. The power tool according to claim 2, wherein an air discharge guide plate is provided at an end of the discharge port in the gear cover. 4. The power tool according to claim 3, wherein an air discharge port is provided at a front end of the gear cover.