JP2002127044A - Motor-driven impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong service life by restraining increase of an internal pressure, in a motor-driven impact tool provided with an impact mechanism and a speed reduction mechanism driven by a motor. SOLUTION: The impact mechanism and the speed reduction mechanism are partitioned by a inner wall 20b provided with a bearing, and a housing 1 is provided with an air vent 20a which makes the speed reduction mechanism communicate with an outside air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric impact tool, such as a hammer and a hammer drill, having an impact mechanism driven by an electric motor and a speed reduction mechanism.

[0002]

2. Description of the Related Art An example of a conventional electric impact tool will be described with reference to FIG. FIG. 2 is a sectional side view of an essential part showing an example of a conventional electric hammer drill.

As shown in the figure, a rotor 3 of an electric motor 2 housed in a housing 1 is engaged with a first gear 4, and the rotational force of the electric motor 2 transmitted to the first gear 4 is equal to that of the first gear 4. It is converted into reciprocating motion by the engaged crankshaft 5, connecting rod 6, and piston 7. Accordingly, the compression of the air chamber 8 fluctuates, and the striker 9 reciprocates and strikes the tip tool 11 held by the tool holder 10.

As described above, the conventional electric impact tool has a crankshaft 5, a connecting rod 6, and a piston 7,
A striking mechanism for converting the rotational force of the electric motor 2 into reciprocating motion to drive the striking element 9; and a speed reduction mechanism having the first gear 4 and transmitting the rotation of the electric motor 2 to the striking mechanism at a reduced speed. You are.

[0005] As shown in FIG.
0 and the outer frame member C21, and the crankshaft 5 is held by a partition wall 20b provided on the outer frame member B20 via a bearing 26. The outer frame member B20 and the outer frame member C21 are covered with a resin outer cover member 22,
The opening 20c provided in the outer frame member B20 is a cover member 2
It is closed by 2. A seal member 23 such as an O-ring is provided between the outer frame member B20 and the outer cover member 22 near the opening 20c, and a seal member 24 is provided between the outer frame member B20 and the outer frame member C21. The lubricating material inserted into the striking mechanism is prevented from leaking outside.

As shown in the drawing, the speed reduction mechanism is an outer frame member A1.
9 and an outer frame member B20, and the outer frame member A19 supports the rotor 3 via a bearing 25. The bearing 25 has a low air permeability with a hermetic seal so as to prevent the lubricant from flowing into the electric motor 2.

[0007]

The above-mentioned conventional electric hitting tool has an outer frame member 19, a seal member and a bearing.
The inside of the striking mechanism 20 and 21 is substantially sealed to prevent the lubricant inserted into the striking mechanism from leaking to the outside. When the temperature rises due to heat generation, the air inside the hermetic seal expands, and the internal pressure rises. When such an internal pressure rise occurs,
O-rings, bearings, etc., which are seal members, may be damaged or prematurely worn, causing leakage of lubricant to the outside and shortening the life of the electric impact tool. In addition, the performance of the impact mechanism using the air spring may be significantly reduced.

An object of the present invention is to provide an electric impact tool capable of solving the above-mentioned drawbacks and improving the life.

[0009]

The above object is achieved by providing a ventilation hole in the housing for communicating the speed reduction mechanism with the outside air.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the electric impact tool according to the present invention will be described with reference to FIG.

FIG. 1 is a longitudinal sectional side view showing an embodiment of an electric hammer drill. As shown in the drawing, the rotating motion of a rotor 3 of an electric motor 2 housed in a housing 1 includes a first gear 4 and a crankshaft 5. , The connecting rod 6 and the piston 7 convert the reciprocating motion. Accordingly, the compression of the air chamber 8 fluctuates, and the striker 9 also reciprocates, and the tool holder 10
The tip tool 11 held by is hit.

The speed reduction mechanism 29 is covered by an outer frame member A19 and an outer frame member B20, and the outer frame members 19 and 20 are further covered by jacket members 17 and 22. Striking mechanism 2
8 is an outer frame member B20, an outer frame member C21, a jacket member B2.
2 is covered.

The striking mechanism and the deceleration mechanism are separated by an internal partition wall 20b provided with a permeable bearing 26 and a bearing 27. The rotor 3 is a bearing 25 with a hermetically sealed seal.
And is supported by the outer frame member A19 through the shaft, so that the ventilation between the speed reduction mechanism and the electric motor 2 is substantially blocked.

Further, each of the outer frame members is provided with seal members 23 and 24 such as O-rings, and has a structure for shutting off inside air and outside air.

As shown in the drawing, an outer frame member B20 covering the speed reduction mechanism portion has a ventilation hole 2 for communicating the speed reduction mechanism portion with the outside air.
0a is provided, and the jacket member 22 and the outer frame member B20 are provided.
A felt 18 that closes the ventilation hole 20a is provided between them. The felt 18 has a structure in which the felt 18 is held by a felt storage portion 17 a provided on the outer cover member 17.

When the electric impact tool having the above configuration is driven, the internal temperature of the main body rises due to the heat generated by the moving member, the air inside the enclosure expands, and the internal pressures of the impact mechanism and the speed reduction mechanism increase. At the beginning, the inflated air escapes to the outside air through the ventilation hole 20a and the felt 18.
In addition, when the operation of the electric impact tool is stopped, the temperature inside the main body decreases, and the inside pressure decreases, so that air enters the inside through the vent hole 20a.

The reason why the ventilation hole 20a is provided so as to communicate with the deceleration mechanism is that the impact mechanism requires a high-stability lubricant, so the ventilation hole is provided so as to communicate with the impact mechanism. This is because even if it is closed by a member such as felt, the lubricant leaks to the outside, and the speed reduction mechanism can use a lubricant with a relatively low consistency.
This is because consideration of lubricant leakage can be achieved by using felt.

The striking mechanism and the deceleration mechanism are divided by a partition wall 20b of the outer frame member B20, and the bearing 26 for supporting the crankshaft 5 has a permeable structure. In addition, it is possible to suppress the lubricating material in the striking mechanism from flowing into the deceleration mechanism, and to allow the air expanded in the striking mechanism to escape from the ventilation holes 20a to the outside air via the deceleration mechanism.

[0019]

As described above, according to the present invention, the striking mechanism and the speed reduction mechanism are separated by the inner wall on which the bearing is arranged, and the housing is provided with a ventilation hole for communicating the speed reduction mechanism with the outside air. Accordingly, it is possible to provide an electric impact tool capable of suppressing an increase in internal pressure, suppressing breakage and wear of the O-ring and the like, and improving the life.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of an electric impact tool according to the present invention.

FIG. 2 is a sectional view of a main part showing an example of a conventional electric impact tool.

[Explanation of symbols]

1 is a housing, 2 is an electric motor, 3 is a rotor, 9 is a hammer, 10 is a tool holder, 11 is a tip tool, 17 is a jacket member, 17a is a felt storage unit, 18 is felt, 19,
20 and 21 are outer frame members, 20a is a vent, 20b is an internal partition, and 20c is an opening.

Claims (4)

[Claims] An electric motor, a tool holder for holding a tip tool, a striker for hitting the tip tool, a strike drive for driving the striker, and a rotation of the electric motor for the strike drive. In a power tool having a deceleration mechanism for decelerating transmission and a housing for covering the same, the impact mechanism and the deceleration mechanism are partitioned by an inner wall provided with a bearing, and the housing is provided with the deceleration mechanism and the outside air. An electric impact tool having a ventilation hole for communication. 2. The power striking tool according to claim 1, wherein said vent hole is covered with felt. 3. The housing has an outer frame member covering the hitting mechanism, and an outer frame member covering the speed reduction mechanism.
The electric impact tool according to claim 1, wherein the ventilation hole is provided in the outer frame member that covers the speed reduction mechanism. 4. An electric impact tool according to claim 3, wherein a resin covering member is provided to cover said outer frame member, and a felt storage portion for holding said felt is provided on said covering member.