JPS6142787Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a safety valve for a pneumatic nailing machine, specifically, a booster that boosts the pressure of primary pressure air supplied from the outside to create high-pressure secondary air, and a booster that creates high-pressure secondary air. When the supply of primary pressure air to a pneumatic nailing machine equipped with a high-pressure air storage chamber for storage is stopped, the high-pressure air remaining in the high-pressure air storage chamber is released to the atmosphere in response to the supply stop. Regarding safety valves for pneumatic nailers.

In general, a pneumatic nailer drives a striking piston for driving nails using compressed air supplied from a high-pressure air supply means such as an air compressor. When driving a nail, a larger striking force is required, so a higher pressure driving air is required. For this reason, a pneumatic nailing machine with a built-in pressure booster has recently been proposed. This pneumatic nailing machine uses a booster that is driven by primary pressure air supplied from a primary pressure air supply means to boost the pressure of primary pressure air or atmospheric air to generate secondary pressure air of higher pressure. This air is constantly stored in a high-pressure air storage chamber, and the striking piston is driven by this high-pressure air as required.

However, the high-pressure air stored in the high-pressure air storage chamber is configured so that it does not flow back to the primary pressure side, so even if the supply of primary pressure air is stopped after the work is completed, the high-pressure air will remain in the high-pressure air storage chamber. Remains indoors. Therefore, even though the primary pressure air is not supplied, the pneumatic nailer is in a state where it can strike, and if used carelessly, it may cause an unexpected accident and is extremely dangerous. be.

The present invention solves the above-mentioned drawbacks, and provides safety for pneumatic nailing machines that can prevent danger by reliably discharging the residual air in the high-pressure air storage chamber especially when the supply of primary pressure air is stopped. The purpose is to propose valves.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the figure, reference numeral 1 indicates a pneumatic nailing machine with a built-in booster. This pneumatic nailing machine 1 boosts the pressure of primary pressure air introduced from a primary pressure air inlet 10 using a booster A, and stores the resulting high-pressure secondary pressure air in a high-pressure air storage chamber B. Then, it acts on the striking piston C as required to drive the piston C, and when the supply of the primary pressure air is stopped, the secondary pressure air is released to the atmosphere by the safety valve D. . This safety valve D is configured as a piston valve, and is provided in the communication passage 2 formed between the primary pressure air introduction side supplied to the booster A and the high pressure air storage chamber B, and is provided in the communication passage 2 formed between the primary pressure air introduction side supplied to the booster A and the high pressure air storage chamber B. When the supply is stopped and the pressure difference with the secondary pressure becomes large, the balance is lost and the air moves to the primary pressure side, causing high pressure air storage chamber B.
This is to release the secondary pressure air inside to the atmosphere.

Next, in the pneumatic nailing machine 1, the pressure increasing mechanism and the nailing mechanism will be briefly explained, and the safety valve D will be explained in detail.

The booster A introduces primary pressure air supplied from an air supply means (not shown) such as an air compressor from an inlet 10 to a differential compression piston 13 in a differential cylinder 12 having a different inner diameter. A large diameter piston portion 13 having a large effective area for receiving working pressure.
Utilizing the fact that the pressing force of a is larger than the pressing force of the small diameter piston part 13b having a small effective area, primary pressure air is applied to the large diameter piston part to lower the compression piston 13, thereby lowering the compression piston 13. 1 inside the small diameter cylinder 12b that acts on the small diameter piston portion 13b.
This compresses and increases the pressure of the next pressure air. After increasing the pressure, conversely, the primary pressure air acting on the large diameter piston portion 13a is exhausted, and the compression piston 13 is compressed by the air pressure of the primary pressure air acting on the small diameter piston portion 13b.
Raise again and repeat the previous compression stroke. The up and down reciprocation of the compression piston 13 is caused by the radial cylinder 12
It is controlled by a timing valve 15 and a switching valve 16 that are fitted coaxially with the compression piston 13 in the upper valve chambers 14a, 14b. The timing valve 15 operates following the compression piston 13 near the top and bottom dead centers of the compression piston 13. The switching valve 16 is
The operation is prompted by the timing valve 15 to switch between supplying the primary pressure air acting on the large diameter piston portion 13a from the air supply means and exhausting the primary pressure air after the action. This is illustrated by Figures 3a-c.

That is, first, the primary pressure air from the inlet 10 is transmitted through the tip opening 11a of the air circulation hole 11 penetrating the piston rod 17 and the side opening 11b branching from the hole 11, to the small diameter cylinder 12b and the small diameter cylinder 12b, respectively. It is supplied to the timing valve chamber 14a. As shown in FIG. 1, when the compression piston 13 rises and is at the top dead center, the large diameter cylinder 12a acting on the large diameter piston portion 13a
The primary pressure air inside the small diameter cylinder 12b is exhausted.
The inside is filled with primary pressure air, but when rising,
As shown in FIG. 3a, a lower engagement step 17 formed on the piston rod 17 of the compression piston 13
b engages with the engagement protrusion 15a of the timing valve 15 near the top dead center and pushes the valve 15 upward. At this time, the lower seal protrusion 15b of the timing valve 15 passes through the supply/discharge port 18, so the upper chamber 19 of the switching valve chamber and the atmosphere communication port 2
0, while the switching valve chamber upper chamber 19 communicates with the timing valve chamber 14a which is supplied with primary pressure air. Next pressure air is fed, and the switching valve 16 is lowered by this air pressure. In addition, 21 is a stopper piston. When the switching valve 16 is lowered, the primary pressure air supply port 22 and the supply/discharge port 23 are opened, and the primary pressure air in the timing valve chamber 14a is transferred to the large diameter cylinder 12 through the ports 22 and 23.
supplied within a. At the same time, when the switching valve 16 is lowered, the exhaust port 24 is shut off, the exhaust of the air inside the large diameter cylinder 12a is stopped, and the supply and discharge of the primary pressure air acting on the large diameter piston portion 13a is switched (Fig. 3). a).

1 from the supply/discharge port 23 into the large cylinder 12a.
When the secondary pressure air flows in, the primary pressure air also flows in from the tip 11a of the communication hole 11 of the piston rod 17 at the same time. However, due to the difference in the effective areas of the pressure receiving parts of the large diameter piston part 13a and the small diameter piston part 13b, the pushing down force acting on the large diameter piston part 13a becomes stronger, and the compression piston 13 descends. At this time, the primary pressure air in the small diameter cylinder 12b is compressed and the internal pressure of the cylinder 12b increases. A check valve 26 is disposed at the tip opening 11a of the air circulation hole 11, and since compressed air cannot flow backward through the air circulation hole 11, secondary pressure air is introduced which opens at the bottom of the small diameter cylinder 12b. The air is sent out from the port 27 to the high pressure air storage chamber B. A check valve 26 is also provided at the secondary pressure air inlet 27, so that the secondary air sent to the high pressure air storage chamber B cannot flow back to the primary side. When the compression piston 13 descends, the upper engagement step 17a of the piston rod 17 engages the engagement protrusion 15 of the timing valve 15 near the bottom dead center.
a to lower the valve 15. At this time, the lower seal protrusion 1 of the timing valve 15
5b passes through the supply/discharge port 18, cuts off the communication between the switching valve chamber upper chamber 19 and the timing valve chamber 14a, and opens the switching valve chamber upper chamber 19 and the atmosphere communication port 20. Switching valve chamber upper chamber 1
Since the primary pressure air in 9 is exhausted through the atmosphere communication port 20, the switching valve 1 is
6 is pushed down by the air pressure acting below it (Fig. 3b).

When the switching valve 16 rises, the communication between the primary pressure air supply port 22 and the supply/exhaust port 23 is cut off, and the supply of primary pressure air is cut off, and at the same time, the supply/exhaust port 23 and the exhaust port 24 are opened. , the air in the large diameter cylinder 12a is exhausted from the exhaust port 29, and the pressure in the large diameter cylinder 12a is reduced. Small diameter cylinder 12
Inside b is the air circulation hole 1 of the piston rod 17.
Since primary pressure air is flowing in from the tip opening 11a of the cylinder 1, the pressure in the small cylinder 12b becomes relatively high compared to the reduced pressure in the large cylinder 12a, and the compression piston 13 is pushed up by this air pressure. It will be done. During the upward movement of the compression piston 13, the upper end of the piston rod 17 hits the stopper piston 21, and due to the resistance, the compression piston 1
3 temporarily stops rising (Figure 3C).

The compression piston 13 waits for the internal pressure of the small diameter cylinder 13b to become close to the original pressure of the primary pressure air, and then continues to rise while pushing up the piston 21 against the downward force of the stopper piston 21, until it reaches the top dead center. do. When the piston rod 17 rises again after a temporary stop, the engaging protrusion 17b of the piston rod 17 again engages with the engaging protrusion 15a of the timing valve 15, thereby pushing the valve 15 upward. At this time, the lower seal protrusion 15b of the timing valve 15 passes through the supply/discharge port 18 to switch the supply/discharge of air from the switching valve chamber upper chamber 19, and the compression piston 13 returns to the position shown in FIG. The operation of the booster A is automatically started until the pressure in the high-pressure air storage chamber B reaches a predetermined pressure, and stops when the pressure reaches the predetermined pressure.

The high secondary pressure supplied from the booster A having the above configuration to the high pressure air storage chamber B is used as drive air for nail driving as required. Next, this will be briefly explained.

First, before driving, the head valve upper chamber 3
3, high pressure air in the high pressure air storage chamber B is introduced through a starting valve mechanism 32, and the head valve 34 is biased downward in the drawing by the action of this high pressure air pressure. In addition, the head 3
A part of the lower end surface of each head valve 34 is exposed in the high pressure air storage chamber B, and is biased upward by the action of the high pressure air in the storage chamber B. It is kept stationary in the lower position due to the difference in the effective area on which high-pressure air acts. When the head valve 34 is in this position, the cylinder 36 is open to the atmosphere, and the driving air supply port 35 communicating with the high pressure air storage chamber B is blocked. Further, the piston C is at the top dead center position, and the driver 37 connected thereto is retracted to the upper position.

Next, after loading the nail 30 into the injection port in the lower part of the main body, the injection port is brought into contact with the surface of the material to be driven, and when the trigger 31 is further pulled, the starting valve mechanism 32 is activated. Therefore, the supply of high pressure air to the head valve upper chamber 33 is cut off, and at the same time, the chamber is opened to the atmosphere. As a result, the downward biasing force that was acting on the upper surface of the head valve is eliminated, and the head valve is moved upward by the action of the high-pressure air in the storage chamber that acts on the lower surface. 34 opens the driving air supply port 35 formed between the cylinder 36 and the high-pressure air storage chamber B, and at the same time, the cylinder 36 is isolated from the atmosphere. The high pressure air in the storage chamber B is instantly and in large quantities delivered to the cylinder 3 from the supply port 35.
This high-pressure air drives the driving piston C, and a driver 37 provided on the piston drives the nail 30 out of the injection port and into the material to be driven.

When the piston C descends, the atmosphere on the lower surface of the piston C in the cylinder 36 is removed as the piston C descends, and is introduced into the piston blowback air reservoir 38 and stored therein.

After driving the nail 30, by releasing the trigger 31, high pressure air is released into the head valve upper chamber 33 through the starting valve mechanism 32.
The high-pressure air inside is introduced again, and the biased force exerted by this high-pressure air on the upper end surface of the head valve 34 causes the head valve 34 to descend, blocking the drive air supply port 35 and opening the cylinder 36 to the atmosphere. do. The piston C returns to the top dead center position by receiving the air pressure in the piston blow-back air reservoir 38 on its lower surface, and is ready for the next driving. In addition, due to the decrease in the pressure in the storage chamber due to the consumption of high-pressure air during the driving operation, the pressure booster A described above
starts automatically and maintains the pressure inside the storage chamber at the desired pressure.

Note that the high pressure air storage chamber B only communicates with the high pressure air inlet 27 and the drive air supply port 35, so unless the drive air supply port 35 is opened, the high pressure air in the storage chamber B is The interior of the chamber B is sealed.

As described above, the primary pressure air supplied from the primary pressure air supply means is boosted by the booster A and stored in the high pressure air storage chamber B, but this high pressure air storage chamber B is It only communicates with the high-pressure air inlet 27 on the side and the drive air supply port 35 on the nail driving side, and since the high-pressure air inlet 27 is provided with a check valve 26, the drive air supply port 35 Unless opened, the high-pressure secondary air in the storage chamber B is sealed within the chamber B, and even if the supply of primary pressure air is stopped, the secondary pressure air remains in the storage chamber B. As shown in detail in FIG. 2, this residual pressure is released to the atmosphere by actuation of a safety valve D provided in the communication passage 2 between the primary pressure side and the high pressure secondary pressure side.

That is, one end of the communication passage 2 opens into the high pressure air storage chamber B, and the other end opens into the primary pressure air introduction section 39 above the booster A. A valve passage 2a is provided within the communication passage 2, and its inner diameter is narrow (indicated as 3b) on the secondary pressure side and wide (indicated as 3a) on the primary pressure side. The safety valve D is disposed within the valve passage 2a, and is configured as a differential piston valve in which the outer diameter on the primary side is larger than that on the high pressure side according to the inner diameter difference of the passage 2a.
It is fitted in a reciprocating manner. Seal rings 6 are attached to the outer peripheries of the large diameter portion 4a with a large outer diameter and the small diameter portion 4b with a small outer diameter to block the communication passage 2. Further, an air vent hole 5 communicating with the atmosphere is formed near the boundary between the primary pressure side and the secondary pressure side of the passage 2a, and this air vent hole 5 is closed when the piston valve D is on the secondary pressure side. When the piston valve D moves to the primary pressure side, it communicates with the high pressure air storage chamber B. In addition, the small diameter portion 4b of the piston valve
Secondary pressure air acts on the large diameter portion 4.
Primary pressure air is acting on a. in this way,
When different pressures are acting from opposite directions on the piston valve D, which has a difference in effective area between the pressure receiving parts, the large area part (in this example, the pressure receiving end of the large diameter part 4a) and the small area part (in this example, the small diameter part) The piston valve D is balanced when the area ratio of the large area portion 4a to the small area portion 4b is equal to the inverse ratio of the pressure ratio for each of the above sections, and the area ratio of the large area section 4a to the small area section 4b is equal to the pressure ratio for each of the above sections. When the ratio becomes larger than the inverse ratio, the piston valve D loses its balance and moves to the small area side. Therefore, in the passage 2a, the valve passage 2a is arranged so that the piston valve D is at least balanced when the secondary pressure reaches the maximum pressure created by the booster.
All you have to do is set the size of .

Since the piston valve D is configured as described above, for example, when the air chuck is removed at the end of work and the supply of primary pressure air to the pneumatic nailer 1 is cut off, the inside of the booster A is closed to the primary pressure air inlet. 10 or exhaust port 29, so 1
1 including booster A at the same time as cutting off the supply of next pressure air.
The primary pressure air on the next pressure side is exhausted, whereas the secondary pressure air in the high pressure air storage chamber B remains in the chamber B. As a result, the air pressure acting on the pressure receiving end of the large diameter portion 4a of the piston valve D in the communication passage 2 communicating the primary pressure side and the secondary pressure side is released, while the air pressure acting on the pressure receiving end of the large diameter portion 4b of the piston valve D is released. Since the secondary pressure air is still acting on the pressure receiving end, the pressure difference becomes extremely large, and the piston valve D is moved to the primary pressure side by the secondary pressure air acting on the pressure receiving end of the small diameter portion 4b. .
Due to this movement, the high pressure air storage chamber B communicates with the air vent hole 5, so that the secondary pressure air in the storage chamber B is released to the atmosphere. The secondary pressure air in the storage chamber is discharged until the pressure becomes almost equal to atmospheric pressure.
In this state, there is no possibility of inadvertent driving. After that, the primary pressure air introduction hole 1
When primary pressure air is supplied from 0, the air acts only on the primary pressure side of the piston valve D, so the piston valve D is pushed back to its original position and the air vent hole 5
The communication between the secondary pressure air storage chamber B and the secondary pressure air storage chamber B is cut off, so that the secondary pressure air is stored in the secondary pressure air storage chamber B.

As described above, according to the present invention, a piston valve including a large area portion and a small area portion having a pressure-receiving effective area ratio larger than the inverse ratio of the pressure ratio between the primary pressure and the secondary pressure is connected to the primary pressure air. It is interposed between the supply side and the high-pressure air storage chamber, and the primary pressure is applied to the large-area portion, while the secondary-pressure air is applied to the small-area portion, so that the primary pressure air is supplied. While communication between the high-pressure air storage chamber and the atmosphere is sometimes cut off, the high-pressure air storage chamber is reliably opened to the atmosphere by stopping the supply of the primary pressure air. Therefore, work can be performed safely and unexpected accidents can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a pneumatic nailing machine equipped with a safety valve according to the present invention, Fig. 2 is an enlarged view of the safety valve, and Figs. 3a to 3c show the operation of the pneumatic nailing machine. FIG. Code, A...booster, B...high pressure air storage chamber,
C...Strike piston, D...Safety valve, 1...
Pneumatic nailer, 2...Communication passage, 4a...Large diameter section, 4b...Small diameter section, 5...Air vent hole, 6...
Seal ring, 12... Differential cylinder, 13...
...Differential compression piston, 15...Timing valve, 16...Switching valve, 17...Piston
Rod.

Claims (1)

[Scope of utility model registration request] In a pneumatic nailing machine equipped with a booster that boosts the pressure of primary pressure air supplied from the outside to create high-pressure secondary air, and a high-pressure air storage chamber for storing this high-pressure air, the above-mentioned primary A piston valve having a large area portion and a small area portion having a pressure receiving effective area ratio of working pressure larger than the inverse ratio of the pressure ratio between the pressure and the secondary pressure is connected to the primary pressure air supply side and the high pressure air storage chamber. interposed between the two to apply primary pressure to the large area portion,
Applying secondary pressure to the small-area portion, cutting off communication between the high-pressure air storage chamber and the atmosphere when supplying the primary pressure, and opening the high-pressure air storage chamber to the atmosphere by stopping the supply of the primary pressure. A safety valve for pneumatic nailers featuring: