JPH09285976A - Motor-driven tool having shaft holding part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a resin member brought into contact with a bearing by increasing the heat radiating action of the bearing so as to suppress heat generation. SOLUTION: A rotary grinding wheel 17 is rotated by receiving the rotary- driving of the motor shaft 4 of a motor 3. The motor shaft 4 is supported in a main body part casing 10 by bearings 5 and 15. The bearing 5 is pressed into a bearing supporting part 6 via a bearing house 2. The bearing supporting part 6 is composed of a resin material as in the case of the main body part casing 10, and the bearing 5 and the bearing house 2 are made of metallic materials. The bearing house 2 includes a heat radiating part 2a, and the friction heat of the bearing 5 produced by the rotary-driving of the motor shaft 4 is radiated through the heat radiating part 2a. Further, since the heat radiating part 2a is positioned in the flow passage of the cool wind of the motor 3 introduced from a wind window 12 to a wind window 13, the heat radiating action of the bearing 5 is increased more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electric power tool having a shaft holder, and more particularly to heat dissipation of the shaft holder.

[0002]

2. Description of the Related Art As an electric power tool, for example, there is a grinder as shown in FIG. A rotary grindstone 17 is attached to the tip of the main body housing 10. Further, a motor 3 is provided in the main body housing 10, and the rotary grindstone 17 rotates by receiving the rotational drive of the motor shaft 4 of the motor 3. A handle portion 11 is connected to the rear end of the main body casing 10, and the operator can switch the switch 1 on the handle portion 11.
The motor 3 starts to be driven by gripping the motor 6.

In order to cool the heat generated by the motor 3, a fan 7 is provided on the tip side of the motor shaft 4. Motor shaft 4
When the fan rotates, the fan 7 also rotates integrally.
As shown in FIG. 5, a wind window 12 is formed in the handle portion 11, and a wind window 13 is formed at the tip of the main body housing 10. By the rotation of the fan 7, cooling air flows from the wind window 12 toward the wind window 13, and the cooling air causes the motor 3 to radiate heat.

The tip of the motor shaft 4 of the motor 3 is supported by a bearing 15, and the rear end of the motor shaft 4 is supported by a bearing 5. The bearing 5 is held by the bearing support portion 6 of the main body housing 10. Here, the main body housing 10 is generally made of a resin material for the purpose of insulating properties and weight reduction of the device, and the bearing support portion 6 is also made of a resin material.

6A and 6B show details of the rear end of the motor shaft 4, the bearing 5, and the vicinity of the bearing support 6. FIG.
In the first conventional example shown in A, the bearing 5 is directly press-fitted into the recess of the bearing support portion 6. The bearing 5 is composed of an inner ring 5b, an outer ring 5c and a steel ball 5a located between them. The motor shaft 4 is inserted into and supported by the inner ring 5b.

When the motor shaft 4 rotates, the inner ring 5b also rotates together with the motor shaft 4, while the outer ring 5c is fixed in the bearing support portion 6 and is immobile. The steel balls 5a interposed between the inner ring 5b and the outer ring 5c rotate to reduce friction between the inner ring 5b and the outer ring 5c and ensure smooth rotation of the motor shaft 4.

In the second conventional example shown in FIG. 6B, a bearing housing 18 made of a metal material is press-fitted into the recess of the bearing support portion 6, and the bearing 5 is press-fitted into this bearing house 18. That is, in the second conventional example, the metal bearing housing 18 is provided between the bearing support portion 6 and the bearing 5.

[0008]

The above-described conventional power tool has the following problems. The bearing 5 is made of a metal material to ensure rigidity and durability. For this reason,
Friction heat is generated in the bearing 5 by the rotation of the motor shaft 4 of the motor 3, and in the first conventional example shown in FIG. 6A, the friction heat of the bearing 5 causes the bearing support portion 6 to be melted and deformed. Occurs.

In order to avoid such an inconvenience, FIG. 6B
In the second conventional example shown in, the bearing house 18 is provided between the bearing support portion 6 and the bearing 5. However, also in the second conventional example, since the bearing house 18 is made of a metal material, the friction heat of the bearing 5 is conducted to the bearing house 18, and the heat of the bearing house 18 melts and deforms the bearing support portion 6. The problem arises.

Therefore, an object of the present invention is to enhance the heat radiation effect of the bearing to suppress the heat generation and avoid the deformation of the resin member in contact with the bearing.

[0011]

According to a first aspect of the present invention, there is provided an electric power tool having a shaft holding portion, the electric power tool being provided in a housing and in the housing.
In a power tool including a drive unit that rotationally drives a drive shaft, a shaft holding unit that holds the drive shaft in a housing, and a tool unit that operates by receiving rotational drive of the drive shaft, the shaft holding unit includes a heat dissipation member. The frictional heat generated by the rotational drive of the drive shaft is dissipated through the heat dissipating member.

According to a second aspect of the present invention, there is provided an electric power tool having the shaft holding portion according to the first aspect, wherein the heat radiating member of the shaft holding portion has a flow of cooling air introduced into the housing. It is characterized by being located on the road.

[0013]

In the electric tool having the shaft holding portion according to the first aspect of the present invention, the shaft holding portion has the heat radiating member, and the frictional heat generated by the rotational driving of the drive shaft is radiated through the heat radiating member. . Therefore, it is possible to enhance the heat dissipation effect of the shaft holding portion and suppress the heat generation of the shaft holding portion, and it is possible to avoid, for example, the deformation of the resin member or the like that directly or indirectly contacts the shaft holding portion.

In the electric tool having the shaft holding portion according to the second aspect, the heat dissipation member of the shaft holding portion is located in the flow path of the cooling air introduced into the housing. Therefore, heat dissipation of the shaft holding portion can be promoted, and the heat dissipation effect of the shaft holding portion can be further enhanced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

1. 1st Embodiment 1st Embodiment of the electric tool which has a shaft holding part which concerns on this invention is described based on FIG. 1, FIG. In this embodiment, a grinder will be described as an example of an electric tool.

A rotating grindstone 17, which is a tool, is attached to the tip of the main body 10 as a housing. Further, a motor (driving unit) 3 is provided in the main body casing 10, and the rotary grindstone 17 is rotated by the rotational drive of the motor shaft (driving shaft) 4 of the motor 3. Main body case 1
The handle portion 11 is connected to the 0 rear end, and the operator grips the switch 16 of the handle portion 11 to start driving the motor 3.

In order to cool the heat generated by the motor 3, a fan 7 is provided on the tip side of the motor shaft 4. Motor shaft 4
When the fan rotates, the fan 7 also rotates integrally.
As shown in FIG. 1, a wind window 12 is formed in the handle portion 11, and a wind window 13 is formed at the tip of the main body housing 10.

The rotation of the fan 7 causes cooling air to enter the inside through the wind window 12, and the cooling air is guided to the inside through the ventilation port 14 at the rear end of the main body casing 10 and passes through the inside of the main body casing 10. It flows out from the wind window 13. The motor 3 radiates heat by this cooling air.

The tip of the motor shaft 4 is supported by a bearing 15, and the rear end of the motor shaft 4 is supported by a bearing 5. Bearing 15, bearing 5
Is made of a metal material to ensure rigidity and durability. A detailed side sectional view of the vicinity of the bearing 5 is shown in FIG. 2A. The bearing 5 is composed of an inner ring 5b, an outer ring 5c and a steel ball 5a located between them. The motor shaft 4 is inserted into and supported by the inner ring 5b.

When the motor shaft 4 rotates, the inner ring 5b also rotates integrally with the motor shaft 4, while the outer ring 5c does not move. The steel balls 5a interposed between the inner ring 5b and the outer ring 5c rotate to reduce friction between the inner ring 5b and the outer ring 5c and ensure smooth rotation of the motor shaft 4.

The bearing support portion 6 is made of a resin material like the main body housing 10, and the bearing support portion 6 is provided.
The bearing house 2 is press-fitted into the concave portion of. The bearing house 2 is made of a metal material and has a heat dissipation portion (heat dissipation member) 2a. In the present embodiment, the bearing 5 and the bearing house 2 are shaft holding portions.
Note that FIG. 2B is a rear view of the main body housing 10.

The bearing 5 is the bearing house 2
It is supported by being pressed into. That is,
A bearing house 2 made of a metal material and having a heat radiating portion 2a is provided between the bearing support portion 6 and the bearing 5.

When the motor 3 is driven to rotate the motor shaft 4, the rotation of the motor shaft 4 causes frictional heat in the bearing 5. The friction heat of the bearing 5 is conducted to the bearing house 2 made of a metal material. Here, the bearing house 2 has the heat dissipation portion 2a as described above. This 2a projects outward with respect to the bearing 5, and the heat conducted from the bearing 5 to the bearing house 2 is radiated through the 2a. Therefore, the heat radiation effect of the bearing 5 can be enhanced, the heat generation of the bearing 5 can be suppressed, and the deformation of the bearing support portion 6 can be avoided.

Further, the heat dissipation portion 2a of the bearing house 2
Are located in the flow path of the cooling air guided into the main body housing 10 through the wind window 12. Therefore, bearing 5
The heat dissipation of the bearing 5 can be promoted, and the heat dissipation effect of the bearing 5 can be further enhanced.

2. Second Embodiment A second embodiment of the power tool having the shaft holding portion according to the present invention will be described with reference to FIG. 3A is a detailed side sectional view of the vicinity of the bearing 5, and FIG. 3B is a main body housing 10.
FIG.

In this embodiment, a bearing house 20 is used instead of the bearing house 2 in the first embodiment.
The bearing house 20 is provided between the bearing support 6 and the bearing 5. The bearing house 20 is also made of a metal material like the bearing house 2. In the present embodiment, the bearing 5 and the bearing house 2 are shaft holding portions.

The bearing house 20 has a heat dissipation portion (heat dissipation member) 20a. This 20a is positioned so as to project outward with respect to the bearing 5, and the heat conducted from the bearing 5 to the bearing house 20 is 20a.
Heat is dissipated through. Therefore, the heat dissipation effect of the bearing 5 can be enhanced, the heat generation of the bearing 5 can be suppressed,
It is possible to avoid deformation of the bearing support portion 6.

Further, the heat dissipating portion 20 of the bearing house 20.
“A” is located in the flow path of the cooling air guided into the main body housing 10 through the wind window 12. Therefore, the heat dissipation of the bearing 5 can be promoted, and the heat dissipation effect of the bearing 5 can be further enhanced.

In this embodiment, the heat radiating portion 20a is inclined with respect to the axis of the motor shaft 4 at a predetermined inclination angle. The heat radiating portion 20a is inclined toward the cooling air (see FIG. 1) guided from the wind window 12 toward the wind window 13. Therefore, the flow of the cooling air is improved along the heat radiating portion 20a, and there is no obstacle to the flow of the cooling air.

Further, by improving the cooling air,
The cooling air entering from the wind window 12 can be efficiently guided toward the outer peripheral surface of the motor 3. The rest of the configuration is similar to that of the first embodiment.

3. Third Embodiment A third embodiment of the electric power tool having the shaft holding portion according to the present invention will be described with reference to FIG. 4A is a detailed side sectional view of the vicinity of the bearing 5, and FIG. 4B is a main body housing 10.
FIG.

In this embodiment, a bearing house 25 is used instead of the bearing house 2 in the first embodiment.
The bearing house 25 is provided between the bearing support 6 and the bearing 5. The bearing house 25 is also made of a metal material like the bearing house 2. In the present embodiment, the bearing 5 and the bearing house 25 are shaft holding portions.

The bearing house 25 has a heat radiating portion (heat radiating member) 25a. The heat radiating portion 25a is located so as to project outward with respect to the bearing 5, and the heat conducted from the bearing 5 to the bearing house 25 is
Heat is dissipated through the heat dissipating portion 25a. Therefore, the heat radiation effect of the bearing 5 can be enhanced, the heat generation of the bearing 5 can be suppressed, and the deformation of the bearing support portion 6 can be avoided.

Further, the heat dissipation portion 25 of the bearing house 25
“A” is located in the flow path of the cooling air guided into the main body housing 10 through the wind window 12. Therefore, the heat dissipation of the bearing 5 can be promoted, and the heat dissipation effect of the bearing 5 can be further enhanced.

In this embodiment, the heat radiating portion 25a is composed of a plurality of twist blades 25b, and the twist blades 25b are provided at a predetermined twist angle with respect to the surface of the heat radiating portion 25a. Since the heat radiating portion 25a is composed of the plurality of twist blades 25b, the cooling air can be swirled in the main body housing 10 to pass therethrough, and heat radiation can be further promoted. In addition, the cooling air passes between the twisted blades 25b, and the heat radiating portion 25a does not obstruct the flow of the cooling air. The rest of the configuration is similar to that of the first embodiment.

4. Other Embodiments The heat dissipation portion 25a shown in the third embodiment (FIG. 4) is
Similar to the heat radiating portion 20a of the second embodiment (FIG. 3), the heat radiating portion 20a may be tilted at a predetermined tilt angle with respect to the axis of the motor shaft 4. Further, in each of the above-described embodiments, the bearing house 2, 20, 25 having the heat radiation portions 2a, 20a, 25a is provided as a separate member with respect to the bearing 5. However, the heat dissipation member may be directly provided on the inner ring 5b or the outer ring 5c of the bearing 5.

The present invention is not limited to those shown in the above embodiments. For example, although a grinder is illustrated as an electric tool in each of the above-described embodiments, other electric tools having a shaft holding portion can be applied. Further, although the bearing 5 and the bearing houses 2, 20, and 25 are illustrated as the shaft holding portion, the drive shaft is held in the housing and has a heat radiating member that radiates frictional heat generated by rotational driving of the drive shaft. Other configurations can be adopted as long as they are used.

Although the bearing 5 and the bearing houses 2, 20 and 25 have been exemplified as metal materials, the bearing 5 may be made of another material having rigidity and durability. 2. The bearing house 20 and the bearing house 25 may be made of another material having a high thermal conductivity.

[Brief description of drawings]

FIG. 1 is a first electric tool having a shaft holder according to the present invention.
FIG. 3 is an overall side sectional view showing the grinder which is the embodiment of FIG.

2 is a detailed side cross-sectional view of the vicinity of the bearing 5 shown in FIG. 1, and B is a rear view of the main body housing 10. FIG.

FIG. 3 is a second electric power tool having a shaft holder according to the present invention.
FIG. 3 is a view showing a grinder which is an embodiment of the present invention, A is a detailed side sectional view of the vicinity of the bearing 5, and B is a rear view of the main body housing 10.

FIG. 4 is a third electric power tool having a shaft holder according to the present invention.
FIG. 3 is a view showing a grinder which is an embodiment of the present invention, A is a detailed side sectional view of the vicinity of the bearing 5, and B is a rear view of the main body housing 10.

FIG. 5 is an overall side sectional view showing a conventional grinder.

FIG. 6A is a detailed side sectional view of the vicinity of the bearing 5 according to the first conventional example, and B is a detailed side sectional view of the vicinity of the bearing 5 according to the second conventional example.

[Explanation of symbols]

 2 ... Bearing house 2a ... Heat dissipation part 3 ... Motor 4 ... Motor shaft 5 ... Bearing 10 ... Main body housing 20.・ ・ ・ ・ Bearing house 20a ・ ・ ・ Heat dissipation part 25 ・ ・ ・ Bearing house 25a ・ ・ ・ Heat dissipation part

Claims (2)

[Claims] 1. A housing, a drive unit that is provided in the housing, and drives the drive shaft to rotate, a shaft holding unit that holds the drive shaft in the housing, and a tool unit that operates by receiving rotational drive of the drive shaft. In the electric power tool including, the shaft holding portion has a heat radiating member, and the frictional heat generated by the rotational driving of the drive shaft is radiated through the heat radiating member. Power tool to have. 2. A power tool having a shaft holder according to claim 1, wherein the heat dissipation member of the shaft holder is located in a flow path of cooling air guided into the housing. An electric power tool having a shaft holding portion.