JPH08323645A - Pneumatic fixture driving machine - Google Patents

Abstract

PURPOSE: To provide a pneumatic fixture driving machine which is provided with a simple structure check valve and returns a part of exhaust gas to a return air chamber. CONSTITUTION: A pneumatic fixture driving machine is provided with a trigger device 6 which controls the supply of pressurized air to a main valve 15 so that normally the main valve 15 is set at the lower stationary position and, during operation, it is set at the upper driving position. Also a return air chamber 13 is formed between the lower part of a main cylinder 9 and a housing 3. Then the main housing 15 is formed with a hollow cylindrical body, its lower end part is brought in contact with the main cylinder 9 so as to seal the main cylinder, and its upper end part is brought in contact with the inner walls of the housing so as to provide a form to seal the upper end of the main valve. In addition, an air hole 30 passing through from the inside to the outside is formed at a middle height and a check valve O-ring 31 which allows air flowout from the inside to the outside but prevents air flowin from the outside to the inside is provided on the outer peripheral surface in which holes are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic fastener driving machine such as a nail driving machine, and more particularly, to use the exhaust of pressurized air when returning from a driven state to a stationary state to return a main piston. Pneumatic fastener driving.

[0002]

2. Description of the Related Art A driving member such as a blade is driven by a piston / cylinder device by using pressurized air, and a fastener such as a nail is driven into an object to be driven such as wood by the driving member. Pneumatic fastener drive tools are very well known. A typical structure of this pneumatic fastener driving machine is a housing in which a reservoir for storing pressurized air is formed, a main cylinder in the housing, and a reciprocating motion in the main cylinder. Main piston connected to the driving member that drives the fastener in the lower nose, a stationary position that blocks the supply of compressed air to the main cylinder, and compressed air is supplied from the top of the main cylinder to the top of the main piston. A main valve that moves between the driving position and a trigger device that controls the pressurized air to the main valve so that the main valve is in the rest position when not operating and the main valve is in the driving position when operating. A return that collects pressurized air between the outer periphery of the lower part of the main cylinder and the inside of the housing in order to return the main piston. Achanba is provided.

In the fastener driving machine having such a structure, the trigger valve is operated to move the main valve in the stationary position to the driving position to rapidly move the main piston to the lower nose side. Then, the operation of the trigger device is released to move the main valve, which was in the driving position, to the stationary position to stop the supply of pressurized air to the upper surface of the main piston, and to return the return air chamber between the main cylinder and the housing. To supply pressurized air to the lower surface of the main piston to return the main piston.When returning, the air in the main cylinder on the upper side of the main piston is exhausted to the outside of the housing. I am sending fasteners to the nose. Since such a fastener driving machine is convenient and convenient, it is widely used in construction sites.

[0004]

By the way, when the main piston is returned, the exhaust gas from the cylinder chamber on the upper surface of the main piston is wastefully discharged to the outside of the housing, resulting in a large air consumption amount. there were. For this reason, part of the exhaust gas is returned to the return air chamber,
A pneumatic fastener driving machine for assisting the return of the main piston has been developed (see Japanese Patent Laid-Open No. 6-780). In this fastener driving machine, since a part of the exhaust gas is returned to the return air chamber, the air consumption amount is reduced, the noise accompanying the exhaust gas is reduced, and the efficiency is improved. However, in the above pneumatic fastener driving machine, as a check valve for preventing backflow of air from the return air chamber to the main valve, an exhaust return passage that returns a part of the exhaust gas from the main valve to the return air chamber. A valve main body that moves in a tubular passage and a coil spring that biases the valve main body in a certain direction are provided. Since the valve main body and the coil spring are provided in the small-diameter exhaust return passage, the structure becomes a little complicated, and the assembly becomes troublesome and expensive. Therefore, an object of the present invention is to provide a pneumatic fastener driving machine that returns a part of exhaust gas to a return air chamber and has a check valve having a simple structure.

[0005]

In order to achieve the above object, according to the present invention, a driving for hitting a main cylinder and a fastener arranged in a reciprocating motion in the main cylinder and located at a lower nose. A main piston to which members are connected, a housing provided so as to cover the main cylinder from the outside and having a reservoir for storing pressurized air inside, a substantially hollow cylindrical shape, and the main cylinder is formed at the lower end. It contacts the upper end surface of the main cylinder and stops the supply of pressurized air to the main cylinder. The main valve that moves between the upper driving position where compressed air is supplied and the main valve that is normally located in the lower stationary position, and the main valve when operating And a trigger device for controlling the supply of pressurized air to the main valve so that the main piston is located at the upper driving position, and when the main piston is lowered to the driving position between the lower part of the main cylinder and the housing. A return air chamber for accumulating air on the bottom side of the main piston is formed.By operating the trigger device, the main valve is moved to the driving position and pressurized air is supplied from the reservoir to the main cylinder to lower the main piston. Abruptly to the nose side of the main piston, then release the operation of the trigger device to move the main valve to the lower rest position to stop the supply of pressurized air to the upper surface of the main piston and The air is discharged to the atmosphere, and pressurized air from the return air chamber is supplied to the bottom surface of the main piston to move the main piston upward. In a pneumatic fastener driving machine that returns to the stop position, the main valve has an O-ring for the check valve that allows the outflow of air from the hollow part to the outside but blocks the inflow of air from the outside to the inside. A pneumatic fixing device is provided, wherein a part of the exhaust gas from the main cylinder on the upper surface side of the main piston when the main piston returns is returned to the return air chamber through the air hole of the main valve. A driving machine is provided,
Since the main valve is equipped with a check valve, the exhaust return passage does not require a check valve.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a nailing machine 1 as a pneumatic fastener driving machine has a housing 3 consisting of a portion for covering the piston cylinder device from the outside and a portion forming a handle 2 for holding the nailing machine. A supply port (not shown) for supplying pressurized air from the outside is provided at the end of the handle 2 of the housing 3, and the inside of the handle 2 serves as a reservoir 5 for storing the pressurized air. The handle 2 is provided with a trigger device 6. A nose 7 for driving a nail as a fastener is integrally provided at the lower portion of the portion of the housing 3 that covers the piston cylinder device from the outside.
The nails are fed one by one from a nail feeding section (not shown).

Inside the housing 3, there is a main cylinder 9
And a blade 1 as a driving member which is arranged so as to reciprocate in the main cylinder and drives a nail in the nose 7.
A main piston 11 to which 0 is connected is provided. A return air chamber 13 is formed between the outer periphery of the lower portion of the main cylinder 9 and the inner wall of the housing 3, and a return air chamber 13 for storing pressurized air for return is formed and communicates with the main cylinder through a lower hole 14 of the main cylinder 9. A main valve 15 is provided above the main cylinder 9 to control the supply of pressurized air to the main cylinder 9 and its stop. For this control, the main valve 15 has a lower stationary position (position in FIG. 1) that blocks the supply of pressurized air to the main cylinder 9 and a pressurized air in the reservoir 5 from above the main cylinder 9 to the main piston. 11 and the upper driving position (position in FIG. 2) for supplying to the upper surface of 11 are moved.

Due to the movement of the main valve 15, a control air passage 17 extends from the trigger device 6 to a control air chamber 18 of the main valve 15. When the pressurized air is supplied to the control air chamber 18 through the trigger device 6, the main valve 15 is held in the lower rest position, and the pressurized air in the control air chamber 18 passes through the control air passage 17 and the trigger device 6 to the atmosphere. When discharged, the main valve 15 moves to the upper driving position. In this way, the main valve 15 is controlled by the trigger device 6.

The trigger device 6 includes a valve housing 19, a valve pin 21, and a trigger lever 22. A trip lever 23 that pushes up the valve pin 21 is pivotally supported at the tip of the trigger lever 22, and the tip of the trip lever 23 extends to the base side of the trigger lever 22. Like the known nail driver, when the nose 7 is not pressed against the driving target, the rod 25 of the safety device does not push the tip of the trip lever 23 to the operating position, so that the trigger lever 22 is pulled. Even if trip lever 23 is valve pin 2
I try not to push 1 up. When the rod 25 pushes up the tip of the trip lever 23 to the operating position, the valve pin 21 is pushed up by pulling the trigger lever 22. The valve pin 21 is in a resting position (Fig. 1).
Position) and the pushed-in driving position (position in FIG. 2).

When the valve pin 21 is in the rest position in FIG. 1, pressurized air enters the valve housing 19 from the reservoir 5, and the pressurized air in the valve housing 19 passes through the control air passage 17 and the control air chamber of the main valve 15. Enter 18. That is, in the stationary position, the pressurized air of the reservoir 5 is supplied to the control air chamber 18, and the main valve 15 is pushed down to press the upper end of the main cylinder 9 so as to seal it. Next, as shown in FIG. 2, with the rod 25 pushing the trip lever 23 up to the operating position (that is, with the tip of the nose 7 pressed against the object to be driven), the trigger lever 22 is pulled to pull the valve pin 21. When the is pushed up to the driving position, the supply of the pressurized air to the valve housing 19 is stopped, and at the same time, the pressurized air in the control air chamber 18 is exhausted to the atmosphere through the control air passage 17 and the lower portion of the valve housing 19. It As a result, the air pressure that pushes down the main valve 15 decreases to atmospheric pressure, and the air pressure of the pressurized air in the reservoir 5 applied to the lower end side of the main valve 15 causes the main valve 15 to rise and move to the driving position, The seal at the upper end of the cylinder 9 disappears and the reservoir 5
Is supplied to the upper part of the main cylinder 9 to push down the main piston 11.

The main valve 15 is formed of a hollow cylindrical body and allows air to pass through it. A large-diameter flange 26 is formed at the lower end of the main valve 15 to contact the upper end surface of the main cylinder to seal the main cylinder 9, and a control air chamber 18 is formed at the outer edge of the flange 26. An outer peripheral wall portion 27 is formed, and a seal member is attached to the lower end portion. The upper end of the main valve 15 is shaped so as to seal the end of the hollow cylindrical body when it comes into contact with the sealing seat 29 provided on the inner wall of the housing 3. Further, at the intermediate height position of the main valve 15, an air hole 30 penetrating from the inside to the outside of the hollow cylindrical body.
Are formed in plural. On the outer peripheral surface having the air holes 30, the check valve O that allows the outflow of air from the inside to the outside but blocks the inflow of air from the outside to the inside.
A ring 31 is provided.

What vertically supports the main valve 15 is a main valve guide 33 which vertically supports the cylindrical portion of the main valve 15 on its outer peripheral surface.
The main valve guide 33 is fixed to the housing 3. The main valve guide 33 uses the main valve 15
Has a portion that supports the outer peripheral surface of the outer peripheral wall portion 27 so as to be movable up and down, and at this portion, the control air chamber 18 is sealed from a portion other than the control air passage 17 (for example, the reservoir 5) by a seal member. . The control air chamber 18 is provided with a coil spring 34 that gently pushes the main valve 15 downward between the flange 26 of the main valve 15 and the main valve guide. When pressurized air is supplied to the reservoir 5,
As described above, the pressurized air is supplied to the control air chamber 18, and the pressing force acts on the upper surface of the flange 26. On the other hand,
On the lower surface side of the flange 26, the pressurized air of the reservoir 5 acts and the force of constantly pushing up the flange 26 acts. When the pressure receiving area on the upper surface side of the flange 26 is larger than the pressure receiving area on the lower surface side of the flange 26, when pressurized air is supplied to the control air chamber 18, the main valve 15 is held in the lower stationary position, The pressing force of the coil spring 34 is not required. In this case, the coil spring 34
When pressurized air is not supplied to the main valve 15
A weak object that holds the button down is sufficient.

The main valve guide 33 is provided with a second air hole 35 for sending the exhaust air passing through the air hole 30 of the main valve 15 to the outside of the main valve guide 33. Further, on the outside of the air hole 35, the housing 3
A space 37 for the exhaust air passing through the air holes 30 and 35 is formed between and. An exhaust gas return passage 38 is formed between the space 37 and the return air chamber 13, and the exhaust air passing through the air hole 30 of the main valve 15 is returned to the return air chamber 13. On the other hand, the other exhaust not returned to the return air chamber 13 is exhausted to the outside of the housing 3 as usual.
Therefore, the main valve 15 has a hollow center.
An exhaust passage 39 communicating with the hollow portion is formed in the housing portion above the main valve 15. The diameter of the exhaust passage 39 is narrowed so that a part of the exhaust is sent to the air hole 30 with the check valve.

When the main valve 15 is in the driving position, the exhaust passage 39 is blocked from communicating with the hollow portion of the main valve by contacting the upper end of the raised main valve 15 with the sealing seat 29. In the driving position, the pressurized air on the upper surface of the main piston is prevented from coming out of the exhaust passage 39. Further, in the main valve guide 33, a small diameter portion 41 that seals the air hole 30 by bringing the check valve O-ring 31 into close contact with the outer surface of the main valve when the main valve 15 moves up to the driving position.
And a large diameter portion 43 that allows the O-ring 31 to freely open and close when the main valve 15 descends to the rest position. By sealing the air hole 30, the pressurized air inside the main valve 15 is prevented from flowing out, whereby the pressurized air in the main valve 15 is maintained when the main valve 15 is in the driving position, It does not impair the rapid and powerful downward pressing of the main piston 11.

The operation of the pneumatic nailer 1 will be described with reference to FIGS.
This will be described with reference to FIG. 1 shows the stationary position, FIG. 2 shows the driving position, and FIG. 3 shows the state of returning to the stationary position. In the rest position of FIG. 1, pressurized air is supplied from the reservoir 5 to the control air chamber 18 through the trigger device 6 and the control air passage 17. The main valve 15 is held at a lower stationary position by the pressurized air in the control air chamber 18, and the lower surface of the flange 26 of the main valve 15 contacts the upper end of the main cylinder 9 so that the main cylinder 9 is sealed by the seal member.
The upper end of is sealed and the supply of pressurized air to the main cylinder 9 is blocked.

Next, as shown in FIG. 2, when the tip of the nose 7 is pressed against the driven object and the rod 25 of the safety device pushes up the trip lever 23 to the operating position, the trigger lever 22 is pulled. The valve pin 21 is pushed up to the driving position, and the supply of pressurized air to the valve housing 19 is stopped. At the same time, the air in the control air chamber 18 flows into the control air passage 1
7 and the lower portion of the valve housing 19 are exhausted to the atmosphere, and the air pressure in the control air chamber 18 is reduced. When the air pressure in the control air chamber 18 drops to atmospheric pressure, the pressing force of the upper surface of the flange 26 of the main valve 15 decreases, while
Since the air pressure of the pressurized air of the reservoir 5 is applied to the lower surface of the flange 26, the main valve 15 is moved upward along the main valve guide 33. By this movement, the flange 26 is separated from the upper end surface of the main cylinder 9. As a result, the pressurized air in the reservoir 5 is rapidly supplied to the main cylinder 9 from the upper end.

By the supply of the pressurized air, the main piston 11 is rapidly pushed downward, the blade 10 is rapidly moved to the lower nose side, and the nail in the nose 7 is driven into the object to be driven. Be done. At this time, the main piston 1
Air on the lower surface side of No. 1 is accumulated in the return air chamber 13 through the lower hole 14 of the main cylinder 9. In addition,
At the driving position, the exhaust passage 39 has the main valve 15
Is sealed by the upper end of the
Also, since the small diameter portion 41 of the main valve guide 33 is sealed by closely contacting the check valve O-ring 31, the rapid downward pressing of the main piston 11 is not impaired, and the striking force of the blade 10 is strong. Maintained.

Then, as shown in FIG. 3, when the trigger lever 22 is released, the valve pin 21 is lowered, and the pressurized air in the reservoir 5 is again supplied to the control air chamber 18 through the trigger device 6 and the control air passage 17. As a result, the air pressure of the pressurized air is applied to the upper surface of the flange 26 of the main valve 15, and the main valve 15 is pushed down. The main valve 15 is pushed down, the flange 26 comes into contact with the upper end of the main cylinder 9, seals the upper end of the main cylinder 9, and stops the supply of pressurized air from the reservoir 5. By pushing down the main valve 15, the exhaust passage 39 of the housing 3 is opened, and the forced seal of the air hole 30 of the main valve 15 is also released, so that the discharge on the upper surface side of the main piston 11 of the main cylinder 9 is performed. The air passes through the inside of the main valve 15 and is sent to the upper exhaust passage 39 to be discharged to the atmosphere as it is.
5, through the space 37 and the exhaust gas return passage 38, the gas flows into the return air chamber 13.

This inflow continues until the pressure in the return air chamber 13 becomes equal to the pressure in the main cylinder 9 on the upper surface side of the main piston 11. After reaching the same pressure, the air on the upper surface side of the main piston 11 continues to be exhausted to the atmosphere through the exhaust passage 39. On the other hand, since the pressure in the return air chamber 13 is maintained by the check valve O-ring 31, a pressure difference is generated between the upper surface side and the lower surface side of the main piston 11, and the main piston is returned upward to ensure that Ascend to top dead center. As a result, the main piston 11 is also returned to the rest position shown in FIG.

[0020]

According to the present invention, when the main piston is returned, the exhaust gas from the main cylinder on the piston upper surface side is returned to the return chamber without being exhausted to the outside unlike the conventional case. Is used for returning to the stationary position, it is possible to save the air that was conventionally supplied and consumed from the reservoir for returning the main piston. Further, since the exhaust gas is used, the energy efficiency is increased, and the noise generated by the exhaust gas is reduced. Further, according to the present invention, since the main valve is provided with the check valve, the check valve is not required in the exhaust gas return passage, which can simplify the configuration of the check valve and simplify the assembly. Can greatly reduce the price.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a stationary state of a nail driving machine as a pneumatic fastener driving machine according to the present invention while omitting a part of a handle, a magazine and the like.

FIG. 2 is a view similar to FIG. 1 showing a driving state of the nail driving machine of FIG.

3 is a view similar to FIG. 1 showing a returning operation of the nail driver of FIG. 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nail driver (pneumatic fastener driving machine) 3 Housing 5 Reservoir 6 Trigger device 7 Nose 9 Main cylinder 10 Driving member 11 Main piston 13 Return air chamber 14 Lower hole 15 Main valve 17 Control air passage 18 Control air chamber 19 Valve housing 21 Valve pin 22 Trigger lever 26 Main valve flange 30 Main valve air hole 31 Check valve O-ring 33 Main valve guide 35 Second air hole 38 Exhaust return passage 39 Exhaust passage 41 Small diameter portion of main valve guide 43 Large diameter part of main valve guide

Claims (2)

[Claims] 1. A main cylinder, a main piston which is arranged so as to reciprocate in the main cylinder, and which is connected to a driving member for hitting a fixing tool at a lower nose, and which covers the main cylinder from the outside. And a housing formed with a reservoir for storing pressurized air inside,
It is formed in a substantially hollow cylindrical shape, and its lower end abuts the upper end surface of the main cylinder to prevent the supply of pressurized air to the main cylinder. Close the main valve that moves from the upper end of the main cylinder to the upper driving position that supplies pressurized air from the reservoir to the upper surface of the main piston, and in the normal operation place the main valve in the lower rest position. A trigger device for controlling the supply of pressurized air to the main valve so as to be located at the upper driving position, and the main piston is lowered to the driving position between the lower portion of the main cylinder and the housing. At this time, a return air chamber for accumulating air on the lower surface of the main piston is formed. Position to supply pressurized air from the reservoir to the main cylinder to rapidly move the main piston to the lower nose side, then deactivate the trigger device to move the main valve to the lower rest position. Then, the supply of the pressurized air to the upper surface of the main piston is stopped, the air on the upper surface of the main piston is discharged to the atmosphere, and the pressurized air from the return air chamber is supplied to the lower surface of the main piston to move the main piston upward. In the pneumatic fastener driving machine for returning to the stationary position, the main valve has an O-ring for a check valve that allows air to flow from the hollow portion to the outside but blocks air from flowing from the outside to the inside. A part of the exhaust gas from the main cylinder on the upper surface side of the piston when the main piston is returned is provided in the air hole of the main valve. Pneumatic fastener driving machine, characterized in that it is returned to the return air chamber through. 2. The pneumatic fastener driving machine according to claim 1, wherein a main valve guide that supports the main valve so as to be vertically movable on an outer peripheral surface of the main valve is fixed to the housing. An air hole of the main valve and a second air hole communicating with the check valve O-ring are formed in the guide, and an exhaust gas return is provided between the second air hole portion and the return air chamber. A passage is formed in the main valve guide, and when the main valve rises to the driving position, the check valve O-ring is brought into close contact with the outer peripheral surface of the main valve to prevent outflow of internal air. Pneumatic type characterized in that a small diameter portion and a large diameter portion for freely opening and closing the check valve O-ring when the main valve descends to the rest position are formed. Fastener driving machine.