JPH09140095A - Hand held disc grinder - Google Patents

Abstract

(57) [Summary] [Purpose] An object of the present invention is to provide a handheld disc grinder that has high cooling efficiency and can suppress a temperature rise of an electric motor part and the like, and is small and lightweight. [Composition] An intake port 4 and an exhaust port 5 are provided on the outer surface of a grinder, and one cooling fan 2 is provided on each of a load side and an anti-load side of a rotating shaft 11 which is one component of a rotor 14,
3 is a hand-held disc grinder with improved cooling efficiency inside the commutator motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hand-held disc grinder, and more particularly to a cooling fan for effectively cooling the inside of a motor for driving the grinder.

[0002]

2. Description of the Related Art Electric power tools, including a hand-held disc grinder, are provided with one cooling fan on the load side of a rotating shaft of a rotor as an internal cooling method for the electric motor. Since this grinder is held and held by hand, the temperature of the grip must be kept within the temperature that can be held by hand even when the load is applied and the temperature rises to the maximum. I have to. In addition, in consideration of safety such as prevention of electric shock and burns, the temperature limit value of each part such as a winding part is defined by technical standards and various standards for electric appliances.

Further, this disc grinder is required to have a high output as compared with other electric tools, and even if it is divided, a higher output is required in the case of a powerful grinder. And consumers are looking for a strong grinder that is light, grindable and powerful.

[0004]

The hand-held disc grinder is required to have a high output as compared with other electric tools such as electric drills, and the powerful grinder is required to have a higher output. Therefore, as compared with other electric tools, an electric motor having a large volume of the core and the copper wire must be used, and the grinder becomes heavy. In addition, the inside of the grinder and the handle part must be kept within a reference temperature, and the current situation is that we are struggling during development.

The present invention has been made in view of the above circumstances, and provides a handheld disk grinder which has a high cooling effect, can suppress a temperature rise of an electric motor part, etc., and is small and lightweight. Is an issue.

[0006]

The cooling efficiency inside the commutator motor can be increased by providing one cooling fan on each of the load side and the anti-load side of the rotating shaft, which is one component of the rotor. You can solve the problem.

[0007]

[Function] The rotor is rotated by turning on the switch and energizing the stator and the rotor in the grinder. This rotation is transmitted to the deceleration mechanism portion and is decelerated to rotate the grindstone. Due to this energization, heat is generated in the coils of the stator and the rotor, and the temperature of the grinder rises around the coil portion. further,
By using this grinder, a load is applied to the grindstone, the current value increases, and the temperature of the coil part gradually rises. Further, due to the rotation of the rotor, frictional heat is generated from the bearing portion and the gear portion. These heats are transmitted to the outer shell and the temperature of the frame etc. rises.

Further, the A cooling fan and the B cooling fan rotate together due to the rotation of the rotor. By the rotation of the B cooling fan, the cooling air flows in through the suction port, and by the rotation of the A cooling fan, the warm air is discharged through the exhaust port and is cooled by the cooling air around the coil portions of the rotor and the stator. . Further, since the temperature rise of the coil portion and the like is suppressed, the heat transfer to the outer shell is reduced and the temperature rise of the grip portion is suppressed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on an embodiment shown in the drawings. FIG. 1 is a sectional view (large disk grinder) of a main portion according to an embodiment of the present invention, and FIG. FIG. 6 is a cross-sectional view of a main part (small disc grinder) according to an embodiment of the present invention.

In FIGS. 1 and 2, the rotor 14 is rotatably held by a bearing via a rotary shaft 11. The load-side shaft end is connected to a reduction mechanism (not shown), and the shaft end of the reduction mechanism has a grindstone 9 on it.
Is fastened. Further, two cooling fans, an A cooling fan 2 and a B cooling fan 3, are mounted on the rotating shaft 11. An intake port 4 is formed on the non-load side, and an exhaust port 5 is formed on the load side.

A hand-held disc grinder 1 having the shape shown in FIG.
Is often used for a large grinder having a grindstone 9 having a diameter of 150 mm or 180 mm, and a grip portion 10 and a handle 8 are provided. In the hand-held disc grinder 1b having the shape shown in FIG. 2, the diameter of the grindstone 9 is 100 mm or 12 mm.
Often used in small 5 mm grinders, and some grinders are also equipped with a handle 8.

A stator 15 is provided inside the frame 12.
And a brush holder (not shown) is held.

In such a structure, when the switch 13 is turned on, a current flows through the stator 15 and the rotor 14 to rotate the rotor 14. This rotation is transmitted to the deceleration mechanism portion (not shown) via the rotating shaft 11 to decelerate the rotation, and this rotation is transmitted to the grindstone 9 to rotate the grindstone 9.
This energization raises the temperatures of the coils of the stator 15 and the rotor 14. Then, by using this grinder, a load is applied to the 9 parts of the grindstone, the current value increases, and the temperature of each part further rises.

Further, the rotation of the rotor causes friction in the bearing portion and the gear portion to generate frictional heat. These heats are transmitted to the outer shell and the temperature of the frame and the like rises.

In the conventional internal cooling of a grinder, one cooling fan mounted on the load side of a rotary shaft is rotated to allow cooling air to flow in through an inlet and to discharge warm air through an outlet. The inside was being cooled.

However, since the size of the cooling fan in the radial direction is determined by the size of the inner diameter of the frame, this size is limited. Therefore, there is a limit to the amount of cooling air with only one cooling fan, and there is also a limit to the internal cooling.

As a countermeasure against this, by providing one cooling fan on each of the load side and the anti-load side, the cooling air 6 passing through the narrow gaps between the stator 15 and the rotor 14 and between the stator 15 and the frame 12 is provided. The amount of airflow is doubled, and the cooling efficiency of each part such as the coil part is significantly improved. As a result, the temperature rise of the coil portion, the bearing portion, the frame 12 and the like can be significantly suppressed.

By improving the cooling efficiency, it is possible to prevent burnout of the coil and locking of the bearing, which is a bearing, and by improving the efficiency of the electric motor, it is possible to reduce the size and weight of the liner.

When the grinder having the shape shown in FIG. 1 is used, the grip 10 and the handle 8 are held by both hands, and the switch 13 provided on the handle 8 is operated to perform the work. In the case of the grinder having the shape shown in FIG. 2, the work is performed by holding the vicinity of the central portion of the frame 12 with one hand or both hands.

As the material and type of the cooling fan, a resin molded product, an iron plate pressed product, an aluminum cast product, etc. can be considered.

In addition to the hand-held disc grinders 1 and 1b, the present invention can be applied to other electric tools such as electric drills, disc sanders, polishers, vibration drills and electric hammers.

[0022]

As described above, in the handheld disc grinder of the present invention, the cooling efficiency in the grinder is greatly improved by mounting two cooling fans on the rotary shaft, and the temperature of the coil portion, the bearing portion, the frame, etc. is improved. Since the rise can be suppressed, it is possible to prevent the coil from burning and the bearing from locking.

Further, since the efficiency of the electric motor is improved, the size and weight can be reduced.

[0024]

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part according to an embodiment of the present invention (large disc grinder).

FIG. 2 is a sectional view of a main part according to an embodiment of the present invention (small disc grinder).

[Explanation of symbols]

 1-Handheld disk grinder 2-A cooling fan 3-B cooling fan 4-Suction port 5-Exhaust port 6- Cooling air 7 ... Warm air 8 ... Handle 9 ... Grinding stone 10 ... Grip 11 ... Rotating shaft 12 ... Frame 14 ... ... Rotor

Claims (1)

[Claims] 1. A hand-held disk grinder in which a grindstone is rotated by the power of a commutator motor, wherein an intake port and an exhaust port are provided in an outer shell of the grinder, and a load side and an antiload of a rotating shaft which is one component of the rotor. A handheld disc grinder characterized in that the cooling efficiency inside the commutator motor is enhanced by providing one cooling fan on each side.