JPH09109055A - Start control valve for pneumatically driven nailing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a main valve of a pneumatically driven nailing machine from bouncing so as to dissolve the instability of nailing action. SOLUTION: A cylindrical part 30a axially protruded with an outer diameter almost equal to the inner diameter of an exhaust port 11 is provided at the end face of a slide 30 of a start operating valve 28 for pilot-operating a main valve. The cylindrical part 30a is fitted into the exhaust port 11 in a stand-by position. When the slide 30 is lowered by trigger operation, the cylindrical part 30a is detached from the exhaust port 11 immediately before the slide 30 closes a pressure air port, and a control pilot port of the main valve is connected to the exhaust port 11, so that the main valve is switched to drive a nail. The time of the simultaneously opened state of the pressure air port and exhaust port 11 is extremely short, so that the main valve is prevented from bouncing by the unstable fluctuation of control pilot pressure of the main valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control valve for an air driven nailer, and more particularly to a start control valve for pilot-operating a main valve of a portable air driven nailer.

[0002]

2. Description of the Related Art A portable air-driven nail driving machine drives a piston in a cylinder with high-pressure air to drive a nail with a driver rod connected to the piston. The piston is activated by opening the valve. The main valve is pilot-operated by the start control valve, and the start control valve is directly or indirectly operated by the trigger mechanism including the trigger lever and the contact arm.

FIG. 4 shows a starting control valve of a conventional air driven nail driving machine, 1 is a housing of the nail driving machine, 2 is a trigger lever, and 3 is an uppermost slide arm portion of a contact arm. Two-part sleeves 5 and 6 of the start control valve 4 are fixed to the housing 1, and a hollow slide 7 is provided in the sleeves 5 and 6.
Is inserted. A trigger valve spool 8 is inserted in the slide 7, and a lower stem 8a of the trigger valve spool 8 projects downward from the center of the lower sleeve 6.

The air pressure of the pressure air chamber 9 acts on both the upper and lower surfaces of the slide 7, and in the standby state of FIG. 4A, the difference in the pressure receiving area between the upper and lower sides and the interposition between the slide 30 and the trigger valve spool 8. The slide 7 is in the raised position by the urging of the mounted spring 10, and the upper end surface of the slide 7 presses against the exhaust port 11 provided above the slide 7 so as to face the slide 7, thereby closing the exhaust port 11. There is. A passage 12 formed around the upper end portion of the sleeve 5 communicates with a control pilot port 13 of the main valve, and when the exhaust port 11 is closed, the control pilot port 13 of the main valve has a pressure air arranged above the sleeve 5. It communicates with the pressure air chamber 9 through a port (not shown). Further, when the slide 7 descends, the exhaust port 11 is opened to connect the control pilot port 13 of the main valve and the exhaust port 11, and the pressure air port is closed by the outer peripheral surface of the upper end portion of the slide 7. .

Trigger lever 2 and contact arm 3
Is operated and the trigger valve spool 8 is pushed in, the pressure air acting on the lower surface of the slide 7 is discharged to the atmosphere, and as shown in FIG. While closing the pressure air port with
The control pilot port 13 of the main valve is connected to the exhaust port 11. As a result, the pilot pressure air of the main valve is exhausted and the main valve is switched,
Compressed air is supplied to the cylinder and the cylinder starts.

[0006]

A conventional start control valve for a pneumatic driven nailer has a structure in which the end face of the slide is pressed against the exhaust port to close the exhaust port, and therefore the exhaust port is provided between both ends of the slide stroke. There is a transition period in which both the pressure air port and the pressure air port are open simultaneously. During this transition period, the control pilot port of the main valve communicates with the exhaust port and the pressure air port, so that the pilot pressure becomes unstable and the main valve may bounce. When the main valve bounces, so-called dribbling occurs in which the piston and driver rapidly move up and down, which hinders nailing.

Further, during the transition period, the high pressure air in the pressure air chamber is discharged to the atmosphere due to the communication between the exhaust port and the pressure air port, so that there is a drawback that the pressure loss is large.

Therefore, the range in which the exhaust port and the pressure air port are simultaneously opened during the sliding operation is shortened as much as possible to prevent the unstable operation of the main valve and improve the reliability of the starting operation. However, there is a technical problem to be solved in order to reduce the pressure loss, and an object of the present invention is to solve the above problem.

[0009]

DISCLOSURE OF THE INVENTION The present invention is proposed to achieve the above object, and pilot-operates a main valve for controlling intake and exhaust of a cylinder accommodating a piston of an air-driven nailer. A 3-port 2-way valve operated by pilot pressure of a trigger valve to close an exhaust port at an end surface of a slide, and an A position;
In an activation control valve of an air-driven nailer, which switches the slide to a B position that closes the pressure air port on the outer peripheral surface of the slide and selectively connects the control chamber of the main valve to the pressure air chamber or the exhaust port, An axially protruding cylindrical portion having an outer diameter substantially equal to the inner diameter of the exhaust port is provided on the end surface of the slide, and the cylindrical portion is fitted into the exhaust port at the A position, and from the exhaust port at the B position. The present invention provides a start control valve for an air-driven nailing machine, characterized in that it is formed so as to separate from each other to open an exhaust port.

When the start control valve is switched between the A position for closing the exhaust port and the B position for closing the pressure air port, the closed state of the exhaust port is within the stroke range corresponding to the length of the tubular portion. Continued. Therefore, the stroke range in which the exhaust port and the pressure air port are simultaneously opened is reduced, and the unstable period of the control pilot pressure of the main valve is shortened as much as possible.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. For convenience of explanation, first, the outline of the nail driving machine will be described with reference to FIGS. 1 and 2, and the same parts as those in the conventional example of FIG. 4 will be denoted by the same reference numerals.

FIG. 1 shows an air-driven nailing machine 21 in which a grip 22 is connected to a die-cast housing 1 and a cylinder (not shown) is built in the housing 1. A pressure air chamber is formed around the cylinder and inside the grip portion 22, and an air hose is connected to an air hose connector 23 provided at an end portion of the grip portion 22 to receive supply of high pressure air from the compressor.

The trigger lever 2 provided at the base of the grip portion 22 is pulled to contact the contact arm 3 of the nose portion 24.
When the object is pressed against the object, the main valve 25 built into the head of the cylinder is opened, the high pressure air in the pressure air chamber is supplied to the cylinder, the piston in the cylinder is driven, and the driver rod connected to the piston is nose-pressed. Part 24
The nail inside is hit and the nail is driven into the object. Incidentally, 26
Is a nail magazine that stores connected nails.

FIG. 2 shows an air circuit model of the nail driver 21, in which the main valve 25 inserted between the pressure air chamber 9 and the cylinder 27 is pilot-operated by the start control valve 28 of the 3-port 2-position. The start control valve 28 is pilot-operated by the trigger valve 8.

During standby, the start control valve 28 connects the pressure air chamber 9 and the control pilot port 13 of the main valve 25 by the pilot pressure of the trigger valve A.
In position. Trigger lever 2 and contact arm 3
Is operated to switch the trigger valve 8, the start control valve 2
8 is switched to the B position, and the control pilot port 13 of the main valve 25 communicates with the atmosphere through the exhaust chamber 29. As a result, the main valve 25 moves to the cylinder 2
The position where the pressure air chamber 9 is cut off from 7 is switched to the connection position, the cylinder 27 is activated, and the nail is driven.

FIG. 3 shows a start control valve 28. Like the conventional start control valve, this start control valve 28 is fixed to the lower sleeve 6 having a large diameter fixed to the housing 1 and the upper part of the lower sleeve 6. The trigger valve spool 8 is composed of a small-diameter upper sleeve 5 and hollow slides 30 inserted into the upper and lower sleeves 5 and 6, and the trigger valve spool 8 inserted into the slide 30 constitutes a trigger valve together with the slide 30. The stem 8a projects downward from a central hole of the bottom plate of the lower sleeve 6.

At the upper portion of the slide 30, a tubular portion 30 having substantially the same diameter as the opening portion of the exhaust port 11 arranged above it.
a is provided and the flange portion 3 around the base of the tubular portion 30a is provided.
0b has a diameter larger than the opening area of the exhaust port 11. Therefore, in the standby state shown in FIG. 3A, the tubular portion 30a of the slide 30 in the raised position is inserted into the opening of the exhaust port 11, and the flange portion 30b is attached to the exhaust port 1.
It is in pressure contact with the opening of No. 1.

Trigger lever 2 and contact arm 3
When the stem 8a of the trigger valve is pushed in by operating, the pressure air acting on the lower surface of the slide 30 is discharged through the hole and the slide 30 descends.
Even after b is separated from the opening of the exhaust port 11, the tubular portion 30a is inside the exhaust port 11 and the closed state of the exhaust port 11 is maintained within a stroke range equal to the length of the tubular portion 30a.

Then, the slide 30 is further lowered, and immediately before the outer peripheral surface of the upper portion of the slide 30 closes the pressure air port (not shown) disposed on the upper portion of the sleeve 5, the tubular portion 30a is closed by the exhaust port 11a. From the control pilot port 13 of the main valve 25 as shown in FIG.
Is connected to the exhaust port 11, whereby the pilot pressure of the main valve 25 is released, the main valve 25 is switched, and the cylinder 27 is activated and nails are driven.

As described above, since the state in which the pressure air port and the exhaust port 11 are opened at the same time is extremely short, the control pilot pressure of the main valve 25 fluctuates unstablely and the main valve 25 bounces. There is no.

Trigger lever 2 and contact arm 3
When the operation is released to return to the standby position, the start control valve 28 and the trigger valve spool 8 return to the initial position in the operation stroke opposite to the above-described order, but the slide 30 also moves upward at this time. Since the tubular portion 30a is inserted into the exhaust port 11 almost at the same time when the pressure air port is opened after the start, the state in which the pressure air port and the exhaust port 11 are simultaneously opened is an extremely short time. No bounce of valve 25 occurs.

The present invention is not limited to the above-described embodiment, and various modifications can be made to the configuration of the trigger valve, and it goes without saying that the present invention extends to those modifications.

[0023]

As described above in detail, the start control valve of the air-driven nailer of the present invention is provided with a tubular portion on the end surface of the slide for opening and closing the exhaust port, and the tubular portion is inserted into the exhaust port. Since the exhaust port is closed by closing the exhaust port and the pressure air port at the same time, the stroke range in which the exhaust port and the pressure air port are open at the same time is reduced as much as possible, and the nailing failure due to the bounce of the main valve is prevented from starting. Instability is eliminated and certainty is improved.

Further, since the air leakage of the pressure air chamber in the middle of the slide stroke is reduced, the consumption amount of the pressure air is reduced, which can contribute to the improvement of working efficiency.

[Brief description of the drawings]

FIG. 1 is a side view of an air driven nailer.

FIG. 2 is an explanatory diagram of an air circuit of an air-driven nailer.

FIG. 3 shows an example of an embodiment of the present invention, in which (a) is a cross-sectional view of a standby state of a start control valve of an air-driven nailer, (b).
Is a cross-sectional view of the startup state of the startup control valve.

4A and 4B show a conventional example, in which FIG. 4A is a cross-sectional view of a startup control valve of an air-driven nailer in a standby state, and FIG.

[Explanation of symbols]

 1 Housing 2 Trigger Lever 3 Contact Arm 5, 6 Sleeve 8 Trigger Valve Spool 9 Pressure Air Chamber 11 Exhaust Port 13 Control Pilot Port 21 Air Driven Nailer 25 Main Valve 27 Cylinder 28 Start Control Valve 29 Exhaust Chamber 30 Slide 30a Cylindrical Section 30b Flange section

Claims (1)

[Claims] 1. A three-port two-way valve for pilot-operating a main valve for intake and exhaust of a cylinder accommodating a piston of an air-driven nailing machine, which is operated by pilot pressure of a trigger valve and is provided on an end surface of a slide. The slide is switched between an A position for closing the exhaust port and a B position for closing the pressure air port on the outer peripheral surface of the slide to selectively connect the control pilot port of the main valve to the pressure air chamber or the exhaust port. In the start control valve of the air driven nail driving machine, a cylindrical portion (30a) protruding in the axial direction with an outer diameter substantially equal to the inner diameter of the exhaust port is provided on the end surface of the slide (30), and the cylindrical portion ( Thirty
a) is an air-driven nailing machine characterized by being fitted into the exhaust port (11) at the A position, and separated from the exhaust port (11) at the B position to open the exhaust port. Start control valve.