JPS5850833B2 - Pneumatic impact tool trigger valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a trigger valve for a pneumatic impact tool such as a pneumatic needle driver.

Conventionally, a trigger valve 1 of a pneumatic nailing machine that is commonly used has a trigger valve cylinder 2, as shown in FIG.
is inserted into the nailer main body 3.

The trigger valve cylinder upper part 4 of the trigger valve cylinder 2 communicates with the main air chamber 5 of the nailer main body 3 through a communication hole 8, and the trigger valve cylinder lower part 6 communicates with the atmosphere.

A trigger valve chamber 1 is formed between the trigger valve cylinder upper part 4 and the trigger valve cylinder lower part 6, and this trigger valve chamber 1 is connected to an air passage 10 through a horizontal hole 9.

This air passage 10 is connected to a chamber above a head valve piston of a head valve (not shown).

A trigger valve stem 11 is built into the trigger valve cylinder 2 so as to be able to freely reciprocate in the longitudinal direction of the trigger valve cylinder 2.

This trigger valve stem 11 has a spring receiver projection 12, an intermediate diameter portion 13, a large diameter portion 14, and a stem operating end portion 15 in order from the upper end portion.

In the spring receiver, a compression spring 16 is installed between the protrusion 12 and the upper part 4 of the trigger valve cylinder.

A 01J ring 1γ is fitted into the intermediate diameter portion 13, and the large diameter portion 1
4 has a seal ring 18 fitted thereto.

The stem operation end 15 protrudes further downward from the trigger valve cylinder lower part 6 and faces the trigger 19.

This trigger 19 is attached to the nailer main body 3 so as to be able to pivot freely.

A contact lever 20 is pivotally attached to the trigger 19, and a distal end 21 of the contact lever 20 is locked to a proximal end 23 of a contact arm 22.

When the trigger 19 is pulled, the contact lever 20 presses the trigger valve operating end 15 and the trigger valve stem 11 moves upward.

Therefore, the seal ring 18 separates from the trigger valve cylinder lower part 6, allowing the trigger valve chamber 1 to communicate with the atmosphere and releasing the operating air in the air passage 10 to the atmosphere.

As a result, the upper chamber of the head valve piston is communicated with the atmosphere, the head valve piston rises, and the working air in the main air chamber 5 flows into the main cylinder.

After the seal ring 18 is separated from the trigger valve cylinder lower part 6, the 01J ring 11 is pressed against the inner circumferential wall of the trigger valve cylinder upper part 4, and is placed in a position where it cuts off between the main air chamber 5 and the trigger valve chamber 1. Since the seal ring 18 is fitted, a state occurs in which the seal ring 18 is separated from the lower part 6 of the trigger valve cylinder, and the 01J ring 1γ is not yet in contact with the inner circumferential wall of the upper part 4 of the trigger valve cylinder.

At this time, the operating air in the main air chamber 5 is discharged into the atmosphere from the gap between the trigger valve cylinder lower part 6 and the stem operating end 15, resulting in a near loss.

Moreover, the operating air in the air passage 10 is not released into the atmosphere instantly due to the above-mentioned near loss, which amplifies the near loss and sends an incomplete signal to the head valve, resulting in failure of the main piston return and This had the drawback of causing poor feeding of the feed piston.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the prior art and to provide a valve in which, even when the trigger valve stem is incompletely operated, the related valves such as the head valve operate normally in the same manner as when the valve stem is fully operated. be.

In order to achieve this object distantly, the present invention provides a head valve that opens and closes between a main air chamber and a main cylinder in which a driver is reciprocally driven, and a space between an upper chamber of the head valve piston of this head valve and the main air chamber. Alternatively, the bird that selectively opens and closes between the upper chamber of the head valve piston and the atmosphere has a valve, and the bird has a valve,
A pilot air valve is provided with a valve cylinder, and a pilot air slider slidably disposed within the valve cylinder, having a first communication hole communicating with the main air chamber at one end, and the other end formed within the valve cylinder. It has a hollow pilot valve stem facing the chamber and a trigger valve stem slidably disposed within the valve stem, the pilot valve stem being formed in the trigger valve cylinder and communicating with the upper chamber of the head valve piston. A first position that opens a communication hole between the second communication hole and the main F chamber and closes a gap between the second communication hole and the exhaust passage formed in the valve cylinder, and the main being freely switchable to a second position that closes between the air chamber and the second communication hole and opens between the second communication hole and the exhaust passage;
The trigger valve stem has a first position that opens between the inside of the pilot valve stem and the pilot air chamber, and closes between the pilot air chamber and the atmosphere, and a first position that opens between the inside of the pilot valve stem and the pilot air chamber and closes between the inside of the pilot valve stem and the pilot air chamber. and a second position that closes the gap between the pilot air chamber and the atmosphere and opens a gap between the pilot air chamber and the atmosphere, and during normal operation when the pilot valve stem and the trigger valve stem are switched to the first position. Pressurized air in the main air chamber is supplied into the head valve piston upper chamber through the second communication hole, and the trigger valve stem is switched to a second position by pushing up the trigger valve stem; When the pilot valve stem is switched to the second position by discharging the pressurized air in the pilot air chamber to the atmosphere, the pressurized air in the head valve piston upper chamber flows through the second communication hole and the exhaust passage. It is characterized by being released into the atmosphere through the process.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 2 and 3.

In FIG. 2, a trigger valve 27 is disposed on a grip portion 26 of a pneumatic needle punch main body 25, which is an example of a pneumatic impact tool.

This trigger valve 2γ includes a trigger valve cylinder 28, a pilot valve stem 29, and a trigger valve stem 30.
It consists of

The trigger valve cylinder 28 is formed by combining a trigger valve cylinder outer peripheral part 31 and a trigger valve cylinder inner peripheral part 32.

The upper end of the trigger valve cylinder outer circumference 31 is open and connected to the main air chamber 33 .

A communication hole 34 is bored in the upper wall portion 31a of the trigger valve cylinder outer peripheral portion 31.

This communication hole 34 is connected to an air passage 35 provided in the nailer main body 25.

This air passage 35 is connected to a head valve piston upper chamber 31 of a head valve 36 provided at the upper end portion of the nailer main body 25.
It is connected to the.

A lower portion 31b of the outer circumferential portion 31 of the trigger valve cylinder is configured to open to the atmosphere, and an inner circumferential portion 32 of the trigger valve cylinder is fitted into this lower portion 31b.

There is a difference in the size of the inner diameter between the upper wall 31a and the lower part 31b of the outer peripheral part 31 of the valve cylinder, and the inner diameter of the lower part 31b is thicker than the inner diameter of the upper wall 31a, forming a stepped part 39. do.

A slit that communicates with the atmosphere in the vertical direction is provided in the side wall of the trigger valve cylinder inner circumference 32, and the slit cooperates with the side wall and stepped portion 39 of the valve cylinder outer circumference 31 to form an exhaust passage 38. There is.

Therefore, this exhaust passage 38 is connected to the inside of the valve cylinder outer peripheral portion 31, that is, the inside of the trigger valve cylinder 28.

A relatively shallow valve chamber 41 in which the large diameter portion 40 of the trigger valve stem 30 moves up and down while sliding is formed in the lower part of the trigger valve cylinder inner peripheral portion 32 with an intermediate step portion 52 interposed therebetween.

An opening 42 is provided continuously to this valve chamber 41 .

The inner diameter of the valve chamber 41 is smaller than the inner diameter of other parts of the valve cylinder 28.

The pilot valve stem 29 is formed in a cylindrical shape,
The hollow portion 29a has a lower end opening into the trigger valve cylinder 28 with substantially the same diameter, and an upper end opening into the main air chamber 33 through a communication hole 43.

The pilot valve stem 29 includes a first intermediate diameter portion 44, a small diameter portion 45, a second intermediate diameter portion 46, a stepped portion 41, and a large diameter portion 48 in this order from the upper end to the lower end.

A first O-ring 49 is fitted on the outside of the first intermediate diameter section 44 , a second O-ring 50 is fitted on the outside of the second intermediate diameter section 44 , and a second O-ring 50 is fitted on the outside of the large diameter section 48 . A third O-ring 51 is fitted into the.

Since the outer diameter of the large diameter portion 48 of the pilot valve stem 29 is set to be larger than the inner diameter of the upper wall portion 31a of the valve cylinder outer peripheral portion 31, the pilot valve stem 29 is located at the top dead center. During this period, the stepped portion 47 is engaged with the lower end portion of the upper wall portion 31a.

That is, the upper wall portion 31a functions as an upward stopper for the pilot valve stem 29.

The downward stopper function of the pilot valve stem 29 is performed by the intermediate stepped portion 52 of the trigger valve cylinder inner peripheral portion 32.

The area of the lower end surface 56 of the pilot valve stem 29 is formed to be larger than the area of the upper end surface 60,
This area difference acts to push up the entire pilot valve stem 29 in response to the pressure of working air introduced into a pilot air chamber 51, which will be described later, through the communication hole 43 and the hollow portion 29a.

The hollow portion 29a of the pilot valve stem 29 is arranged such that the large diameter portion 40 of the trigger valve stem 30 slides thereon.

This large diameter portion 40 has a fourth O-ring 54 and a fifth O-ring 54.
A ring 55 is fitted.

This fourth O-ring 54 is connected to the pilot valve stem 29.
When the trigger valve stem 30 is located at the bottom dead center, the trigger is in close contact with the lower end surface 56 of the pilot valve stem 29, and when the trigger valve stem 30 is located at the bottom dead center and the pilot valve stem 29 is located at the top dead center, is separated from the lower end surface 56 and does not come into contact with the intermediate stepped portion 52 of the trigger valve cylinder inner peripheral portion 32.

When the trigger valve stem 30 is located at the bottom dead center, the fifth 01J ring 55 is in close contact with the inner circumferential wall of the valve chamber 41 and blocks the pilot air chamber 51 from the atmosphere. When it is located at the top dead center, it is separated from the intermediate step portion 52 and located within the pilot air chamber 51.

As the trigger 58 is pulled, the trigger valve stem 3
0 rises, the fourth 01J ring 54 comes into close contact with the lower end surface 56 of the pilot valve stem 29, and then the fifth 01J ring 55 separates from the intermediate step portion 52, so that only the working air in the pilot air chamber 51 is released. It is released into the atmosphere through the gap between the stem operating end 30a and the opening 42.

As the trigger 58 is released, the trigger valve stem 3
0 descends, the fifth O-ring 55 comes into close contact with the intermediate stepped portion 52, and then the fourth OIJ song 4 separates from the lower end surface 56 of the pilot valve stem 29, so that the main working air flows into the pilot air chamber 5γ. Working air flows in from the air chamber 33 and pushes up the pilot valve stem 29, and working air flows in from the main air chamber 33 into the head valve piston upper chamber 3T, closing the head valve 36.

Therefore, the triple phenomenon is completely prevented.

Hereinafter, the operating state of this trigger valve 21 will be explained based on FIGS. 2 and 3.

First, as shown in FIG. 2, when the trigger 58 is not yet pulled, the trigger valve stem 30 is located at the bottom dead center, and the large diameter portion 40 of the trigger valve stem 30 enters the valve air chamber 41. The fifth OIJ 55
is in close contact with the inner circumferential wall of the valve chamber 41.

On the other hand, the pilot valve stem 29 is located at top dead center,
The pilot air chamber 57 is filled with working air from the main air chamber 33 via the communication hole 43 and the hollow portion 29a.

At this time, the communication hole 34 is blocked from the exhaust passage 38 by the second 01J ring 50, so the air passage 35 connected to the communication hole 34 and the head valve piston upper chamber 37 connected to this air passage 35 are The operating air is trapped, pushing down the head valve piston 59 and isolating the main air chamber 33 and the main cylinder 61 from each other.

Next, when the trigger 58 is pulled, the trigger valve stem 30 first rises and the fourth 01J ring 54 comes into close contact with the lower end surface 56 of the pilot valve stem 29, and then when the trigger 58 is pulled further, the fifth Or) ring 55 is located within the pilot air chamber 5γ apart from the intermediate step portion 52.

As a result, the working air in the pilot air chamber 51 is released into the atmosphere from the gap between the stem operating end 30a and the opening 42, and the pressure of the working air acting on the lower end surface 56 of the pilot valve stem 29 disappears, the pressure of the working air acting on the upper end surface 60 of the pilot valve stem 29 becomes relatively large, and the pilot valve stem 29 is pushed down by this pressure.

As a result, the communication hole 34 and the exhaust passage 38 are connected by the small diameter part 45 of the pilot valve stem 29, and the working air in the air passage 35 and the head valve piston upper chamber 3γ flows through the communication hole 34, the small diameter part 45, and the exhaust passage 38. The head valve piston 59 is then released into the atmosphere and is pushed up by the working air pressure from the main air chamber 33 acting on the lower end surface, introducing working air into the main cylinder 61.

This state is shown in FIG.

Next, when the bird releases the trigger valve stem 30 from the state shown in FIG.
is pushed down, and first the fifth O-ring 55 comes into close contact with the inner circumferential wall of the valve chamber 41, and then the fourth O-ring 54 separates from the lower end surface 56 of the pilot valve stem 29.

As a result, the working air in the main air chamber 33 is introduced into the pilot air chamber 57 through the communication hole 43 and the hollow part 29a, and acts on the lower end surface 56 of the pilot valve stem 29, causing the pilot valve stem 29 to
is pushed up, and the space between the exhaust passage 38 and the communication hole 34 reaches the second 0
1J ring 50.

At this time, the first 01J ring 49 separates from the upper wall 31 a of the trigger valve cylinder outer circumference 31 and enters the main air chamber 33 , so the working air flows into the first intermediate diameter section 44 of the pilot valve stem 29 . The air is introduced into the air passage 35 through the communication hole 34 from the gap between the outer peripheral part 31 of the trigger valve cylinder and the upper chamber 31 of the head valve piston.
The head valve piston 59 is pushed down and the connection between the main cylinder 61 and the main air chamber 33 is cut off.

Thus, according to the present invention, the pulling and releasing operations of the trigger merely release the working air in the small-capacity pilot air chamber to the atmosphere or introduce the working air into the pilot air chamber. For example, even if the trigger valve stem rises incompletely, the operating air in the pilot air chamber is sufficiently exhausted to ensure that the pilot valve stem operates reliably, and that the head valves related to the valve always have a complete signal. It has the same effect as when it works.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing a trigger valve according to the prior art, FIGS. 2 and 3 are vertical sectional views showing a trigger valve according to the present invention, and FIG. FIG. 3 shows a state in which the trigger is pulled and operated. 2γ...Trigger valve, 28...Trigger valve, cylinder, 29...Pilot valve stem, 30...Trigger valve stem, 33
...Main air chamber, 34...Communication hole, 35...Air passage, 36...Head valve, 3γ...Head valve piston Upper chamber, 38...Exhaust passage, 5γ...Pilot air chamber 61...Main cylinder.

Claims (1)

[Claims] 1. A head valve that opens and closes between the main air chamber and the main cylinder in which the driver is reciprocally driven, and between the head valve piston upper chamber of this head valve and the main air chamber, or between the head valve piston upper chamber and the atmosphere. The trigger valve has a trigger valve that selectively opens and closes between the trigger valve cylinder and the first communication hole that is slidably disposed within the valve cylinder and communicates with the main air chamber at one end. a hollow pilot valve stem whose other end faces a pilot air chamber formed in the trigger valve cylinder; and a trigger valve stem slidably disposed within the valve stem; A valve stem is formed in the trigger valve cylinder and opens between a second communication hole that communicates with the upper chamber of the head valve piston and the main air chamber, and is also formed in the second communication hole and the trigger valve cylinder. a first position that closes a gap between the main air chamber and the second communication hole, and opens a gap between the second communication hole and the exhaust passage; The trigger valve stem is switchable to a second position, and a first position in which the trigger valve stem opens between the inside of the pilot valve stem and the pilot air chamber, and closes between the pilot air chamber and the atmosphere. and a second position that closes between the inside of the pilot valve stem and the pilot air chamber and opens between the pilot air chamber and the atmosphere, and the pilot valve stem and the trigger valve stem are During normal operation when the head valve piston is switched to the first position, the pressurized air in the main air chamber is supplied to the upper chamber of the head valve piston through the second communication hole, and the trigger valve stem is pushed up. When the pilot valve stem is switched to the second position by switching the stem to the second position and releasing the pressurized air in the pilot air chamber to the atmosphere, pressurization of the upper chamber of the head valve piston is performed. A trigger valve for a pneumatic impact tool, characterized in that air is released into the atmosphere through the second communication hole and the exhaust passage.