JP3231946B2 - Air nailer trigger valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trigger valve for an air nailer.

[0002]

2. Description of the Related Art Conventionally, an air nailing machine using compressed air as a driving source generally operates as follows to perform a nailing operation. First, when the trigger is pulled, the stem of the trigger valve is retracted, and the upper chamber of the head valve is communicated with the atmosphere, whereby the head valve is moved upward, and the upper chamber of the striking piston is communicated with the accumulator, and thus the upper chamber of the striking piston. Compressed air is supplied, the impact piston moves down, and the nail is driven. When the striking piston moves down, compressed air in the striking piston upper chamber enters the return air chamber and is stored. After the nail driving is completed, when the pulling operation of the trigger is released, the trigger valve stem is returned forward by the compression coil spring force, etc., and compressed air is again supplied to the upper chamber of the head valve. The upper chamber is shut off from the accumulator, and at about the same time, the upper chamber of the impact piston is opened to the atmosphere. When the impact piston upper chamber is opened to the atmosphere, the compressed air in the return air chamber enters the impact piston lower chamber, and the impact piston is returned upward.

In such an air nailing machine, as described above, the operation of the trigger valve, that is, the movement of the trigger valve stem causes the head valve to move up or down, whereby compressed air is supplied to the upper chamber of the striking piston. , And open to the atmosphere. For this reason, for example, when an incomplete operation (so-called “chunching”) in which one of the trigger and the contact arm does not reach the top dead center is performed, the movement of the trigger valve stem cannot be reliably performed. However, the head valve is not sufficiently moved, so that the supply of compressed air to the upper chamber of the striking piston is insufficient, so that a reliable nailing operation cannot be performed. Moreover, in this case, the compressed air does not enter the return air chamber sufficiently, so that the striking piston cannot be returned, and in some cases, the nail feeder does not operate.

Therefore, as a technique for solving this problem, there has been a trigger valve disclosed in, for example, Japanese Patent Publication No. 58-50833. In this conventional trigger valve, when the trigger valve stem is slightly retracted, the pilot valve stem is moved to the end by compressed air so that the upper chamber of the head valve communicates with the atmosphere. According to this trigger valve, even if the amount of retraction of the trigger valve stem is insufficient due to insufficient operation of the trigger, the volume of the pilot air chamber is very small, and the pilot air chamber is immediately released to the atmosphere. Therefore, since the pilot valve stem is reliably moved to the end by the compressed air, the upper chamber of the head valve is reliably released to the atmosphere, and thus the compressed air is sufficiently supplied to the upper chamber of the striking piston. A reliable nailing operation could be obtained even when hitting was performed.

[0005]

However, in the above-mentioned conventional trigger valve, it is necessary to assemble the stem and the pilot valve stem in a predetermined state in the trigger valve cylinder which is divided into upper and lower parts. There has been a problem that the arrangement becomes complicated, and as a result, it takes time to assemble and adjust the arrangement. The present invention has been made in view of this problem, and it is possible to not only obtain a reliable nailing operation even if the trigger operation amount is insufficient, but also take time for assembly and adjustment without complicating the structure. Aim to provide a trigger valve for no air nailer.

[0006]

According to a first aspect of the present invention, in an air nailing machine, a head valve for switching an upper chamber of a striking piston between a state communicating with an accumulator and a state communicating with the atmosphere is operated. A trigger valve for the trigger valve, the stem of the trigger valve is provided with a flange portion for partitioning the lower stem chamber and the upper stem chamber, when the stem is retracted by a part of the entire retreat distance, The invention according to claim 2, wherein the stem is self-moved to the retreat end by a pressure difference between the upper stem chamber and the lower stem chamber generated when the upper stem chamber is opened to the atmosphere. In the trigger valve according to the first aspect, the upper stem chamber communicates with a return air chamber for accumulating compressed air for returning the striking piston to a top dead center, and the stem is connected to a compression chamber in the lower stem chamber. State that has moved to the retracted end by is,
Compressed air is accumulated in the return air chamber, and the accumulated compressed air is released by being supplied to the upper stem chamber, whereby the stem is returned to an initial state.

[0007]

According to the first aspect of the present invention, when the trigger is slightly pulled (or the contact arm is slightly pushed) and the stem of the trigger valve is retreated by a part of the entire retreat distance, The space between the upper stem chamber and the lower stem chamber is shut off, and at the same time, the upper stem chamber is communicated with, for example, a return air chamber, whereby the upper stem chamber is opened to the atmosphere. Here, since the lower stem chamber is always in communication with the accumulator, a pressure difference is generated between the upper stem chamber and the lower stem chamber, and the stem retreats the remaining distance due to the pressure difference. That is, after the stem is retracted by a certain distance by the slight pull operation of the trigger, the stem moves to the retreat end by the pressure difference, not by the pull operation of the trigger (self-moving function).

Accordingly, the retreat speed of the stem is constant regardless of the operation speed of the trigger or the contact arm, that is, regardless of the user's operation, so that the exhaust speed of the upper chamber of the head valve is constant, and thus the impact piston is driven. The force is stabilized, and a stable striking force can be obtained.

Further, even when the operation of the trigger or the like is incomplete and the movement of the stem is inadequate, for example, when a striking operation is performed, the stem upper chamber is retracted until it is communicated with the return air chamber. If this is done, the stem is thereafter reliably retracted to the retracted end position, so that a reliable nailing operation can be obtained. In addition, since the self-moving structure is used by utilizing the pressure difference between the lower stem chamber and the upper stem chamber, the structure can be simplified as compared with the conventional case, so that there is no trouble in assembling and adjusting.

In the process in which the stem of the trigger valve self-moves to the retreat end, the upper chamber of the head valve is opened to the atmosphere and the head valve moves upward, whereby the upper chamber of the striking piston is communicated with the accumulator and the upper chamber of the striking piston is moved from the atmosphere. Will be shut off. When the striking piston upper chamber is communicated with the accumulator, compressed air is supplied to the striking piston upper chamber, so that the striking piston moves from the top dead center to the bottom dead center, and the driver mounted on the striking piston is driven by the driver. The nail is driven out, whereby the nail is driven out from the tip of the driver guide.

When the striking piston almost reaches the bottom dead center, the compressed air in the striking piston upper chamber is supplied to the return air chamber. At this time, since the stem is located at the retracted end position, the upper stem chamber and the return air chamber are in communication with each other, so that compressed air is also supplied to the upper stem chamber. When the pressure in the upper stem rises and the pressure difference between the lower stem and the lower chamber is eliminated or reversed, the pressure receiving area of the compression coil spring and the flange on the upper side of the stem and the pressure receiving area on the lower side of the stem are increased. When a force in the direction of returning forward based on the difference from the area acts and the pull operation such as the trigger is released, the stem is returned forward and the trigger valve is turned off. From this, if the pressure in the return air chamber is not sufficiently increased, that is, if the pressure difference between the lower stem chamber and the upper stem chamber is not eliminated or reversed, the stem is turned off even when the operation of the trigger or the like is released. Not returned to position (self-holding function). Therefore, when the pressure in the return air chamber does not sufficiently increase to the pressure required to completely return the striking piston, for example, when the striking operation is performed as described above, the stem is held at the retracted position and the trigger is stopped. The valve is not turned off. According to this, the next driving operation cannot be performed while the return of the percussion piston is incomplete, so that the nailing operation is not performed with insufficient percussion force or poor nail feed.

In a state in which the impact piston reaches the bottom dead center and the pressure in the return air chamber is sufficiently increased, when the pulling operation of the trigger or the pushing operation of the contact arm is released, the stem is returned to the off position. The upper chamber of the head valve is shut off from the atmosphere, and compressed air is supplied to the upper chamber of the head valve. Then, the head valve moves downward, and the upper chamber of the percussion piston is shut off from the accumulator and opened to the atmosphere. While the upper chamber of the striking piston is opened to the atmosphere, the compressed air of the return air chamber flows into the lower chamber of the striking piston, whereby the striking piston is returned from the bottom dead center to the top dead center, and a single nailing operation is performed. Is completed.

[0013]

According to the first aspect of the present invention, the moving speed of the trigger valve stem becomes constant irrespective of the speed of the pulling operation of the trigger, and a stable striking force can be obtained. Further, the trigger valve stem is reliably moved to the retreat end regardless of the amount of operation of pulling the trigger or the amount of operation of pushing the contact arm. A hitting operation is obtained. Further, the structure can be simplified as compared with the related art, so that the assembling and adjustment do not take much time.

According to the second aspect of the present invention, since the stem of the trigger valve cannot be returned unless the pressure in the return air chamber is sufficiently increased, problems such as a conventional defective return of the driver or a defective nail feed are solved. You.

[0015]

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the entirety of an air nailer 50 including a trigger valve 1 of the present embodiment described below. First, the overall configuration of the air nailer 50 will be briefly described. In the following description, a state in which compressed air is supplied is also referred to as a “compressed air state”, and a state in which the air is released to the atmosphere is also referred to as an “atmosphere released state”.

The air nailing machine 50 is roughly divided into a main body 55 having a substantially cylindrical main body housing 51 with a built-in impact driving section, and a protruding shape formed at the tip (lower end in the figure) of the main body 55. Driver guide 52 assembled to
A handle 53 integrally extending in a radial direction (rightward in the figure) from a substantially central portion of the outer periphery of the main body 55, and one end connected to the driver guide 52, and the other end connected to the handle 53. A substantially cylindrical magazine 54 which is attached to the distal end and accommodates a large number of nails to be supplied to the driver guide 52.

A cylinder 60 extends in the direction of the center axis of the main body 55.
A striking piston 61 is tightly fitted in the cylinder 60 so as to be slidable in the vertical direction in FIG. A driver 62 having a front end facing the inside of the driver guide 52 is integrally attached to the center of the lower surface side of the impact piston 61 in the drawing.

A top cap 56 is mounted on the cylinder head side (upper side in the figure) of the main body housing 51, and an inner peripheral side of the top cap 56 and a substantially upper half of an outer peripheral side of the cylinder 60 in the main body housing 51 are provided. , And a return air chamber 58 is formed substantially in the lower half on the outer peripheral side of the cylinder 60. The accumulator 57 and the return air chamber 58 are air-tightly partitioned by a wall 59.

The handle 53 has a substantially cylindrical shape, and its inner peripheral side is the accumulator 57. An air hose (not shown) is connected to the distal end of the handle portion 53 via a one-touch joint 64, whereby compressed air is supplied into the accumulator 57. On the other hand, the return air chamber 58 communicates with the inner peripheral side of the cylinder 60 only in one direction via the check valve 65. That is, the compressed air in the cylinder 60 flows into the return air chamber 58 via the check valve 65, but the compressed air once flowing into the return air chamber 58 passes through the check valve 65 to the cylinder 60.
It is not returned inside. However, the return air chamber 58 communicates with the inner peripheral side of the cylinder 60 via a communication hole 66 formed in the lower peripheral wall of the cylinder 60. At the lower end of the cylinder 60, a cushion 67 having an appropriate elasticity is attached, and the cushion 67 absorbs the impact when the striking piston 61 is launched.

Next, a head valve 70 is slidably provided in the upper portion inside the top cap 56 in a direction along the center axis of the main body 55 (vertical direction in the figure). The head valve 70 is urged downward in the figure by a compression coil spring 71 interposed between the head valve 70 and the top surface of the top cap 56. The upper chamber 61u and the accumulator 57 are shut off. Conversely, when the head valve 70 is moved upward, an opening is opened between the upper end edge of the cylinder 60 and the accumulator 57 and the striking piston upper chamber 61u communicate with each other.
Compressed air flows into u, so that the striking piston 61 is driven downward in the drawing, and one nail supplied into the driver guide 52 is driven.

When the head valve 70 is moved in the vertical direction, a communication hole 72 for communicating the inner peripheral side of the head valve 70 with the atmosphere is opened and closed. That is, when the head valve 70 is moved downward in the drawing and pressed against the upper end edge of the cylinder 60, thereby shutting off the upper striking piston chamber 61u and the accumulator 57, the communication hole 72 is opened accordingly, and the head The inner peripheral side of the valve 70 and, consequently, the impact piston upper chamber 61u are opened to the atmosphere. Conversely, when the head valve 70 is moved upward against the compression coil spring 71, the communication hole 72 is closed and the percussion piston upper chamber 61u is shut off from the atmosphere, while the upper end edge of the cylinder 60 is closed as described above. And compressed air flows from the accumulator 57 into the upper striking piston chamber 61u.

By moving the head valve 70 in the vertical direction in this manner, the switching between the supply and cutoff of the compressed air to the upper striking piston chamber 61u and the opening and closing of the communication hole 72 allow the air in the upper striking piston chamber 61u to be opened and closed. Opening or shutting off from the atmosphere is switched. This movement of the head valve 70 is performed by supplying compressed air to the head valve upper chamber 70u formed between the head valve 70 and the top cap 56 or by supplying air. It is done by opening. That is, the head valve upper chamber 70u is
Through the communication passage 73, the variable pressure chamber 20 of the trigger valve 1 described later
As shown in the figure, the peripheral edge of the head valve 70 slightly protrudes in the radial direction from the cylinder 60, so that the compressed air of the accumulator 57 always acts on this protruding portion. Therefore, when compressed air is supplied to the head valve upper chamber 70u by operation of the trigger valve 1, the pressure of the compressed air and the pressing force of the urging force of the compression coil spring 71 cause the pushing-up by the compressed air acting on the protruding portion. Since the force becomes larger than the force, the head valve 70 moves downward, and is maintained in a state where the upper striking piston chamber 61u is closed. On the other hand, when the head valve upper chamber 70u is opened to the atmosphere through the communication passage 73, the pushing-down force is only the urging force of the compression coil spring 71, and the pushing-up force of the accumulator 57 acting on the protruding portion by the compressed air is reduced. Therefore, the head valve 70 moves upward against the compression coil spring 71, and the upper striking piston chamber 61u is communicated with the accumulator 57.

As shown, the top cap 56
A cushion 74 is also attached to the upper surface of the striking member 61, and the cushion 74 absorbs the impact when the striking piston 61 moves backward.

Next, the trigger valve 1 for operating the head valve 70 as described above will be described. The trigger valve 1 is housed in a recess formed by partitioning the wall substantially in three directions near the base of the handle portion 53, and is arranged facing the rear side of the trigger 30. An idler 31 is attached to the back of the trigger 30. When the trigger 30 is pulled upward in the drawing, the trigger valve 1 is turned on via the idler 31. Note that the pulling operation of the trigger 30 is valid only when the contact arm 32 is pressed, and if the contact arm 32 is not pressed, the trigger 30 is pulled.
Does not rotate the idler 31 to the predetermined position, so that the trigger valve 1 does not turn on.

Now, as shown in FIG. 2, the trigger valve 1 has a stem 2 and an axial direction (vertical direction in the figure).
The first to third valves 3, 4, and 5 are fitted around the inner peripheral side of the partition wall 1a so as to be movably supported. The stem 2 has a flange portion 2a substantially at the center in the axial direction. In order to provide a difference in pressure receiving area between the illustrated upper surface and the lower surface of the flange portion 2a as described later, the shaft diameter on the upper surface side is slightly smaller than the shaft diameter on the lower surface side. That is, the upper surface side (stem upper chamber 22 described later)
The pressure receiving area of the lower side (the stem lower chamber 2 described later)
1) is larger than the pressure receiving area.

An O-ring 13 is mounted on the peripheral surface of the flange portion 2a, and two O-rings 11 and 12 are mounted on a shaft portion on the tip side (lower side in the figure) of the flange portion 2a. One O-ring 14 is also mounted on the shaft portion on the rear end side (upper side in the figure) of the stem 2, and a total of four O-rings 11 to 14 are mounted on the stem 2. Therefore, in the following description, the tip side (the lower side in the figure)
From the first O-ring 11, the second O-ring 12, the third O-ring 13, and the fourth O-ring 14.

Next, the first valve 3 has a substantially annular shape, and is fixed so as to be immovable in the axial direction (vertical direction in the drawing) in a state of closing the opening of the accommodation recess formed by the partition wall 1a. I have. The shaft portion on which the first and second O-rings 11 and 12 of the stem 2 are mounted is inserted into the inner peripheral hole 3b of the first valve 3 so as to be movable in the axial direction. Further, an exhaust hole 3a for opening to the atmosphere is formed obliquely penetrating between the inner peripheral hole 3b of the first valve 3 and the front surface (the lower surface in the figure), and passes through the exhaust hole 3a. An inner peripheral hole 3b of one valve 3 communicates with the atmosphere. In addition, this first
An O-ring 3c is mounted on the outer peripheral surface of the valve 3 to
a, and the space between the outer periphery of the third valve 3 and the partition wall 1a is kept airtight.

A second valve 4 having an annular shape having a substantially U-shaped cross section is mounted on the inner side (upper side in the figure) of the first valve 3 so as to be movable in the axial direction. An O-ring 4a is also attached to the outer peripheral surface of the second valve 4, so that the partition 1a is slidably contacted while keeping the space between the partitions 1a airtight. This second valve 4
A shaft portion on the distal end side of the stem 2 (the lower part of the neck of the flange portion 2a) is supported by an inner peripheral hole on the smaller diameter side (hereinafter, referred to as “small diameter hole 4b”) so as to be movable in the axial direction. The above-mentioned variable pressure chamber 20 is formed between the second valve 4 and the first valve 3, and the variable pressure chamber 20 communicates with the head valve upper chamber 70 u via the communication passage 73. Then, the stem 2 is retracted, and the first O-ring 11 becomes the inner peripheral hole 3b of the first valve 3.
, The variable pressure chamber 20 is opened to the atmosphere through the inner peripheral hole 3b and the exhaust hole 3a, whereby the head valve upper chamber 70u is communicated with the atmosphere. Since a compression coil spring 6 is interposed between the second valve 4 and the first valve 3, the compression coil spring 6 is urged toward the back (in a direction away from the first valve 3). This will be described later.

Next, at the further back of the second valve 4,
The third valve 5 is fitted in a fitting manner. The third valve 5 has a stepped cylindrical shape, and is arranged in such a direction that the large-diameter portion on the lower side in the drawing faces the second valve 4. The upper end of the third valve 5 is mounted so as to be abutted against the stepped surface of the wall 1a, and the third valve 5 moves substantially in the axial direction by the action of a compression coil spring 7 described later. Fixed to impossible. An O-ring 5a is also attached to the outer peripheral surface of the large-diameter portion to keep the space between the O-ring 5a and the partition 1a airtight.

An inner peripheral hole of a large diameter portion of the third valve 5 (hereinafter, referred to as a "large diameter hole 5b") and an inner peripheral hole of a large diameter side of the second valve 4 (hereinafter, referred to as a "large diameter hole 4c"). The flange 2a of the stem 2 is accommodated in the space defined by the above. The large-diameter hole 4c on the second valve 4 side is formed with a slightly larger diameter than the large-diameter hole 5b on the third valve 5 side. For this reason, as shown in FIG. 2, when the stem 2 is moved forward and the flange portion 2 a is located in the large-diameter hole 4 c on the second valve 4 side, the third O-ring 13 is attached to the large-diameter hole. 4c is not in sliding contact with the inner peripheral wall, so that the flange portion 2a
The lower side of the figure (hereinafter, referred to as “stem lower chamber 21”) and the upper side of the figure (hereinafter, referred to as “stem upper chamber 22”) are in communication with each other. On the other hand, when the stem 2 retreats and the flange portion 2a enters the large-diameter hole 5b of the third valve 5 as shown in FIGS. 3 to 5, the third O-ring 13 moves inside the large-diameter hole 5b. Since the upper and lower stem chambers 22 and 21 are slidably in contact with the peripheral wall, the upper and lower stem chambers 22 and 21 are hermetically shut off. As shown, the compression coil spring 7 is interposed between the flange 2a of the stem 2 and the stepped portion on the inner peripheral side of the third valve 5. For this reason, the stem 2 is biased downward in the figure.
The third valve 5 is held so as not to move downward in the axial direction due to the repulsive force.

Next, the lower stem chamber 21 (both of the upper stem chamber 22 depending on the position of the stem 2) is connected to an accumulator 57 through a communication hole 8 formed in the partition wall 1a. That is, a slight gap is provided between the outer periphery of the second valve 4 and the inner peripheral surface of the partition wall 1a, and at the upper end of the second valve 4 there are provided axially cut recesses 4d at a plurality of circumferential positions. Therefore, even when the second valve 4 is retracted upward in the drawing and is in contact with the lower surface of the third valve 5 (normal state), the inner peripheral side and the outer peripheral side of the second valve 4 communicate with each other. Therefore, the accumulator 57 is always in communication with the inner peripheral side of the second valve 4 via the communication hole 8, the gap between the second valve 4 and the partition 1a, and the cut recess 4d. ing.

Therefore, when the flange portion 2a of the stem 2 is located in the large diameter hole 4c of the second valve 4 (the state shown in FIG. 2), the lower stem chamber 21 and the upper stem chamber 22 are arranged.
Are communicated with the accumulator 57, and the two chambers 21 and 22 are in a state where compressed air is supplied.

The lower stem chamber 21 and the transformer chamber 20 are
The second valve 4 communicates with a small-diameter hole 4b of the second valve 4 via a gap between the distal end shaft portion of the stem 2 and the shaft. Therefore, unless the small-diameter hole 4b is sealed by the second O-ring 12 (or both of the first O-rings 11), the compressed air flowing into the lower stem chamber 21 also flows into the variable pressure chamber 20. The compressed air that has flowed into the variable pressure chamber 20 in this way is
u, thereby causing the head valve 7
0 moves downward, that is, moves in a direction to close the upper striking piston chamber 61u.

Further, a stem retreat chamber 23 for allowing the stem 2 to retreat is provided further in the back of the third valve 5. The stem retreating chamber 23 communicates with a communication hole 9 formed in the partition 1a through a gap between the small diameter portion of the third valve 5 and the partition 1a. This communication hole 9 is
The stem retreating chamber 23 is in communication with the return air chamber 58 at all times.

The stem retreating chamber 23 is provided with the stem 2
When the fourth O-ring 14 is located in the inner peripheral hole (hereinafter, referred to as “small-diameter hole 5c”) of the small-diameter portion of the third valve 5, the state shown in FIG. When the stem 2 is retracted and the fourth O-ring 14 is displaced rearward from the inside of the small-diameter hole 5c (the state shown in FIGS. 4 and 5), the fourth O-ring 14 is communicated with the upper stem chamber 22.

As described above, the trigger valve 1 of this embodiment includes the stem 2 and the first to third valves 3 to 5, and the variable pressure chamber 20 and the lower part of the stem are provided between the first to third valves 3 to 5. Room
The upper chambers 21 and 22 and the stem retreat chamber 23 are provided, and the respective chambers 20 to 23 are switched to a communication state or a cutoff state by movement of the stem 2, whereby the variable pressure chamber 20 and thus the head valve upper chamber 70 u are compressed or air. In addition to switching to the open state, the pressure in the return air chamber 58 (compressed air state or open air state, the same applies hereinafter) is used to switch the upper stem chamber 22 to the compressed air state or open air state. Head valve upper chamber 7
By switching the pressure state of 0u, the striking piston 61 is launched or returned as described above, while by switching the pressure state of the upper stem chamber 22, the stem 2 moves or retracts as described below. Is achieved.

Hereinafter, the operation of the trigger valve 1 will be described in relation to the operation of the main body 55. FIGS. 2 to 6 show a series of operating states of the trigger valve 1.
As shown in the figure, in the following description, the trigger 30 is always in a pulling operation state, for example, in the case of swinging, so that the trigger valve 1 is turned on / off by pushing or returning the contact arm 32. Description will be made assuming that the operation is performed.

First, in the state shown in FIG. 2, the trigger 30 has been pulled but the contact arm 32 has not been pushed (in the drawing, it has not moved upward). For this reason, the idler 31 is not rotated upward in the figure, so that the stem 2 is located at the lower forward position in the figure, and the trigger valve 1 is in the off state. In this state, the transformation chamber 20 is provided with the communication hole 8 and the large-diameter hole 4 of the second valve 4.
c and the small-diameter hole 4b are connected to the accumulator 57. Therefore, the compressed air is supplied to the variable pressure chamber 20, and the head valve upper chamber 70u is in a compressed air state. Since the head valve upper chamber 70u is in a compressed air state, the head valve 70 moves downward and is pressed against the upper end of the cylinder 60. Therefore, the striking piston upper chamber 61u is connected to the accumulator 5
7 and is open to the atmosphere (the state shown in FIG. 1) through the communication hole 72. This is the state when the air nailer 50 is not used.

Next, when the contact arm 32 is retracted by, for example, pressing it against a nail driving material so as to perform nailing by the air nailer 50, the idler 31 rotates backward (upward in the figure) as shown in FIG. Then, the stem 2 moves backward against the compression coil spring 7. The stem 2 retreats from the state of FIG. 3 through the state of FIG. That is, in the process of retreating the stem 2, first, the third O-ring 13 closes the large-diameter hole 5b of the third valve 5 so that the lower stem chamber 21 and the upper stem chamber 22 are shut off. 3
As a result, the stem upper chamber 22 is communicated with the return air chamber 58 via the stem retreating chamber 23. In addition, the small-diameter hole 4b of the second valve 4 is closed by the second O-ring 12 and the variable pressure chamber 20 and the lower stem chamber 21 are shut off.
The O-ring 11 comes off the inner peripheral hole 3b of the first valve 3,
The variable pressure chamber 20 is opened to the atmosphere via the exhaust hole 3a.

Here, as described above, the stem lower chamber 21
When the stem upper chamber 22 is shut off and the stem upper chamber 22 is communicated with the return air chamber 58, the stem lower chamber 21 is always communicated with the accumulator 57 through the communication hole 8 as described above. At this point, the return air chamber 58 is open to the atmosphere, so the upper stem chamber 22 is open to the atmosphere. Therefore, the stem 2 retreats against the compression coil spring 7 due to the pressure difference between the two chambers 21 and 22. That is, when the stem 2 retreats a part of the entire retreat distance by the initial movement of the idler 31, specifically, the third O-ring 13
Closes the large diameter hole 5b of the third valve 5, and when the fourth O-ring 14 comes off the small diameter hole 5c of the third valve 5,
The stem 2 self-moves the remaining retreat distance by the pressure difference between the lower stem chamber 21 and the upper stem chamber 22 without upward movement of the idler 31, that is, by human operation.

In the process of retreating the stem 2 in this manner, the first O-ring 11 comes off the inner peripheral hole 3b of the first valve 3, and the variable pressure chamber 20 is opened to the atmosphere via the exhaust hole 3a, whereby the head valve upper chamber is opened. The head valve 70 is opened to the atmosphere, whereby the head valve 70 moves upward against the compression coil spring 71 by the pressure of the accumulator 57 acting on the protruding portion of the lower peripheral edge, so that the upper striking piston chamber 61 u communicates with the accumulator 57. Then, compressed air is supplied, whereby the striking piston 61 is driven out and nailed.

After the initial movement is given to the stem 2 by manual operation such as pushing operation of the contact arm 32, the stem 2 moves by itself due to the pressure difference between the lower stem chamber 21 and the upper stem chamber 22. The exhaust speed of the variable pressure chamber 20 and thus the head valve upper chamber 70u does not vary as in the case of the conventional manual operation alone. Head valve 70u
, The upward movement speed of the head valve 70 is stabilized, and therefore, the driving speed of the striking piston 61 is stabilized, and the striking piston 61 can be given a stable striking force.

Further, since the stem 2 moves to the retracted end without fail, for example, when a so-called chopping operation is performed, the pushing operation amount of the contact arm 32 is insufficient, or the pulling operation amount of the trigger 30 is insufficient. Since the movement amount of the stem 2 is insufficient due to these manual operations, that is, the head valve 70 is instantly moved upward even when the stem 2 does not retreat to the retreat end by a part of the entire retreat amount. Further, since the compressed air is sufficiently supplied to the upper striking piston chamber 61u, a sufficient driving force of the striking piston 61 is obtained. Since the piston 61 is securely returned to the top dead center, a stable nail driving force or nail driving operation can be obtained regardless of the operator's operation.

Next, when the impact piston 61 is ejected, the return air chamber 58 is open to the atmosphere as described above until the impact piston 61 passes through the check valve 65 of the cylinder 60. After passing through the stop valve 65, the compressed air in the impact piston upper chamber 61u flows into the return air chamber 58 through the check valve 65. Return air chamber 5
When the compressed air flows into 8, the stem retreating chamber 23 and, consequently, the stem upper chamber 22 are also in a compressed air state. Upper stem room 22
Is in the compressed air state, the stem 2 has the flange 2
When the force of moving forward (downward in the figure) is exerted by the difference in pressure receiving area between the upper surface and the lower surface of a and the compression coil spring 7, the restraint of the idler 31 is released by, for example, returning the contact arm 32 to the front. , The stem 2 is returned to the front position as shown in FIG.

As described above, after one nailing operation is completed and the impact piston 61 reaches the bottom dead center, the return of the stem 2 depends on the pressure of the stem upper chamber 22 (the pressure received by the upper surface of the flange portion 2a). ) And the urging force of the compression coil spring 7 are the pressure of the lower stem chamber 21 (the pressure received by the lower surface of the flange portion 2a).
It becomes possible only when it becomes larger. That is,
If the pressure in the return air chamber 58 does not become sufficiently high, even if the contact arm 32 is returned or the pulling operation of the trigger 30 is released, the stem 2 is held at the retracted end position without returning to the front. The trigger valve 1 does not return to the off state. In this case, since the upper head valve chamber 70u remains open to the atmosphere, the upper striking piston chamber 61u remains in the compressed air state, and therefore, the striking piston 61 is not returned upward.

From this, since the stem 2 is held at the retracted end position until the pressure in the return air chamber 58 is sufficiently increased, sufficient compressed air for completely returning the striking piston 61 to the return air chamber 58 is obtained. If not supplied, the trigger valve 1 does not return to the off state. In this regard, in the related art, for example, when the above-described chopping is performed, the trigger valve is turned off even if the supply of the compressed air to the return air chamber is insufficient to completely return the striking piston. Therefore, the next time, the nailing operation is performed from the incomplete return of the impact piston, and as a result, a problem such as insufficient impact force or poor nail feed has occurred. According to this, such a trouble does not occur because the trigger valve 1 does not return to the off state unless the main body 55 is in a state in which the main body 55 operates reliably.

Further, when assembling the trigger valve 1, the third valve 5, the stem 2, the second valve 4, and the first valve 3 may be assembled in the housing recess formed by the wall 1 a in this order. The configuration or arrangement is simplified as compared with the related art. Therefore, there is no need to take time for the assembly and adjustment.

In this embodiment, the stem upper chamber 22 is communicated with the return air chamber 58, and the self-movement or self-holding of the stem 2 is realized by utilizing the return air chamber 58 being in air communication. However, the embodiment of the present invention is not necessarily limited to the configuration that communicates with the return air chamber 58. The point is that when the stem 2 retreats to a certain position, the stem upper chamber 2
2 may be configured to be open to the atmosphere.

Next, the stem 2 retreats and the second O-ring 1
2 closes the small-diameter hole 4b of the second valve 4, and when the first O-ring 11 comes off the inner peripheral hole 3b of the first valve 3, the variable pressure chamber 20 is opened to the atmosphere while the lower stem chamber 21 is compressed air. In this state, the pressure difference between the two chambers 20 and 21 causes the second valve 4 to move forward (downward in the figure) against the compression coil spring 6. The state in which the second valve 4 has moved forward is shown in FIGS. FIG. 5 shows the stem 2
6 shows a state in which the second valve 4 has moved forward at the time when it is located at the retreat end, and FIG. 6 shows a state in which the stem 2 is being returned to the front while the second valve 4 has moved forward. I have.

By configuring the second valve 4 to move forward, the air nailer 50 can be switched to a so-called "single-shot". Therefore, this movement of the second valve 4 does not function particularly in the case of so-called "hit and fire". Here, the "hitting" is a function that can continuously perform nailing by pushing the contact arm 32 while the trigger 30 is pulled as shown in the figure, for example, so-called "swinging"
This is a convenient function when performing On the other hand, "single shot" refers to a function in which the next nailing is not performed unless the pulling operation of the trigger 30 is released once for each nailing operation. This function emphasizes the finish so that the machine does not float and hit the nail twice.

This single-unit switching function is not directly related to the present invention, but will be briefly described below. In the drawing, reference numeral 33 denotes a single-shot / repeating switching pin formed by forming a cut of a predetermined shape in the radial direction.
If the rotation position 3 is the illustrated rotation position, the idler 31 can be returned to the lowest position while being allowed to cut, even if the trigger 30 is kept in the pulled state. Become. When the single switching pin 33 is rotated in an arbitrary direction from the "striking" state, the idler 31 is blocked by a portion where the cut of the single switching pin 33 is not formed (a hatched portion in the figure). It is not returned to the lowermost position. That is, the idler 31 is held at an intermediate position only by releasing the pushing operation of the contact arm 32, and it is necessary to release the triggering operation of the trigger 30 to return the idler 31 to the lowermost position.

As described above, since the idler 31 is not completely returned, the stem 2 is also held at the middle position without being completely returned to the off position. As the stem 2 is held in the middle position and the second valve 4 moves forward as described above, the first O-ring 11 closes the inner peripheral hole 3b of the first valve 3 and the second O-ring 12 The state where the small diameter hole 4b of the two valve 4 is closed is realized. Note that this state corresponds to a state in which the stem 2 is slightly retracted in FIG.

In this state, the transformer chamber 20 and the stem lower chamber 21
Is still shut off, no compressed air is supplied to the transformation chamber 20, and therefore the head valve upper chamber 70
Since u is still kept open to the atmosphere and the upper striking piston chamber 61u is maintained in the compressed air state, the striking piston 61 is maintained at the bottom dead center without returning to the top dead center. You. The striking piston 61 is not returned to the top dead center.
Pressing does not nail. To release this state, the pulling operation of the trigger 30 may be released. That is, when the pulling operation of the trigger 30 is released, the idler 31 is returned further forward from the halfway position, and the stem 2 is completely returned to the off position.
Since 0 is communicated with the lower stem chamber 21, compressed air is supplied to the variable pressure chamber 20, and further, compressed air is supplied to the upper head valve chamber 71 u to lower the head valve 70, so that the striking piston upper chamber 61 u is moved. After being released to the atmosphere, the impact piston 61 is returned to the top dead center by the compressed air in the return air chamber 58. Since the striking piston 61 is returned to the top dead center, the trigger 30 is pulled and the contact arm 3 is operated.
By pressing 2, the next single shot can be performed.

In this regard, if the pin 33 is located at the "fire" position, the operation of the contact arm 32 is released without releasing the pull operation of the trigger 30, and the idler 31 is returned to the lowest position. Therefore, since the stem 2 is completely returned to the off position, the variable pressure chamber 20 and the lower stem chamber 21 are instantaneously communicated, and the variable pressure chamber 20 is in a compressed air state. Therefore, the second valve 4 is moved backward by the compression coil spring 6. At the same time, the striking piston 61 is returned to the top dead center. Therefore, when the contact arm 32 is pushed next time, nailing is continuously performed while the trigger 30 is being pulled.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of an air nailer according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view when a trigger valve is off.

FIG. 3 is a longitudinal sectional view showing a state at the time when the stem is retracted by a part of the entire retreat distance. At this point, the first O
The ring 11 is just before coming off the inner peripheral hole 3b of the first valve 3, and the second O-ring 12 is a small diameter hole 4b of the second valve 4.
And the third O-ring 13 immediately after closing the large-diameter hole 5b of the third valve 5, and the fourth O-ring 1
4 is immediately before the small diameter hole 5c of the third valve 5 comes off.

FIG. 4 is a longitudinal sectional view of the trigger valve showing a state where the stem has moved to a retracted end. In this state, the transformer room 2
0 is opened to the atmosphere, the lower stem chamber 21 and the upper stem chamber 22 are shut off, and the upper stem chamber 22 and the stem retreating chamber 23, and furthermore, the return air chamber 58 are communicated.

FIG. 5 is a longitudinal sectional view of the trigger valve, showing a state in which the idler is returned but the stem is self-held at the retracted end position, and a state in which the second valve 4 has moved forward.

FIG. 6 is a longitudinal sectional view of the trigger valve in a state where the stem is being returned to the front after the second valve has moved forward.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Trigger valve 2 ... Stem 2a ... Flange part 3 ... 1st valve, 4 ... 2nd valve, 5 ... 3rd valve 8, 9 ... Communication hole 11, 12, 13, 14 ... 1st-4th O-ring 20 ... Transformation chamber 21 ... Stem lower chamber, 22 ... Stem upper chamber, 23 ... Stem retraction chamber 30 ... Trigger, 31 ... Idler, 32 ... Contact arm 50 ... Air nailer 57 ... Accumulator, 58 ... Return air chamber 61 ... Striking Piston, 61u: Upper chamber of impact piston 70: Head valve, 70u: Upper chamber of head valve

Claims (2)

(57) [Claims] 1. A trigger valve for operating a head valve for switching an upper chamber of a striking piston between a state communicating with an accumulator and a state communicating with the atmosphere in an air nailing machine. Providing a flange portion for partitioning the lower stem chamber and the upper stem chamber and causing the upper stem chamber to open to the atmosphere when the stem is retracted by a part of the entire retreat distance. A trigger valve for an air nailing machine, wherein the stem is self-moved to a retracted end by a pressure difference between the stem and the lower chamber. 2. The trigger valve according to claim 1, wherein
The upper stem chamber communicates with a return air chamber for accumulating compressed air for returning the impact piston to top dead center, and the return air chamber is in a state where the stem has moved to the retreat end by the compressed air in the lower stem chamber. Compressed air is accumulated in the stem, and the accumulated compressed air is released to the upper chamber of the stem to be released and the stem is returned to an initial state.