JPH0223830Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is an efficiency improvement device for a booster, particularly for a booster that compresses and boosts the pressure of primary pressure air supplied from the outside with a piston. The present invention relates to an efficiency improving device for a booster, which is provided with a stop member that delays the return of the compression piston until the air pressure of the next pressure air reaches sufficiently close to the original pressure.

(Prior art) A pneumatic nailer drives a striking piston for driving nails using high-pressure air supplied from a high-pressure air supply means such as an air compressor. When driving a nail into a nail, a greater impact force is required, so a higher pressure drive air is also required. For this reason, a pneumatic nailing machine with a built-in pressure booster has recently been proposed. The pressure booster built into this pneumatic nailer integrates a drive piston with a large effective pressure-receiving area and a small pressure boosting piston,
These are slidably housed in a boost cylinder and a drive cylinder, respectively, and both pistons are driven by supplied air that acts on the drive piston, which has a large effective area for receiving pressure. It compresses and increases the pressure of primary pressure supply air introduced from a compressed air source. Boosted 2
The secondary pressure air is transferred to a high pressure air storage chamber and drives a nail driving striking piston as required.

However, in the above pressure booster, when the primary pressure is introduced into the drive cylinder and the compression piston is moved to the compression stroke, the air pressure introduced into the pressure boosting piston side cylinder which has a small effective pressure receiving area is 1.
When the pressure is lower than the next pressure, the amount of high-pressure air obtained by the compression stroke of the piston is small, so many forward strokes are required to store high-pressure air at a given pressure in a storage chamber of a given capacity. As a result, the consumption of primary pressure air for driving increases, which is not only economically undesirable, but also requires a lot of time, which impedes continuous nail driving work.

(Technical Problems of the Invention) The present invention solves the above-mentioned drawbacks, and in particular prevents the compression piston from moving into the compression stroke until a sufficient amount of primary pressure air acting on the small effective pressure receiving area of the compression piston is supplied. The technical problem is to propose an efficiency improvement device for a booster that can delay the return of the piston.

(Means for Solving the Problems) In order to solve the above problems, the booster efficiency improvement device according to the present invention includes a boost piston with a small effective pressure receiving area that is slidably housed in a boost cylinder, and a drive cylinder. a drive piston with a large effective pressure receiving area that is slidably housed in the booster piston and integrally connected to the booster piston; In a booster that has a switching valve that selectively connects the inside of the cylinder to a primary pressure air source and the atmosphere, and boosts the primary pressure air supplied in the boost cylinder to a higher pressure, the booster piston and A stop member that contacts and receives the piston during the return stroke of the driving piston is provided to apply a biasing force toward the bottom dead center of the piston, and the primary pressure air applies the biasing force of the stop member to the booster piston. It is characterized by being set slightly smaller than the acting return force.

(Operations and Effects of the Invention) As described above, according to the invention, the switching valve operates in the vicinity of the vertical dead center of the boost piston and the drive piston, thereby causing the air pressure to act on the drive piston in the opposite direction. During the return stroke, the primary pressure air supplied into the booster cylinder is compressed by the booster piston and raised in pressure during the compression stroke. By repeating this, the primary pressure air can be increased to a higher pressure than this.

By the way, during the return stroke, both the pistons come into contact with the stop member and receive a braking force toward the bottom dead center, so that the return is stopped. Thereafter, sufficient primary pressure air is supplied into the boosting cylinder, and the return force acting on the boosting piston becomes greater than the braking force, allowing the piston to reach top dead center. Since a sufficient amount of primary pressure air is supplied into the pressure boosting cylinder, efficient pressure rise is performed in the subsequent compression stroke. Therefore, the practical effect is very large.

(Example) 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 nailer with a built-in booster. This pneumatic nailing machine 1 introduces air from an air source (not shown) such as an air compressor through an air inlet 11, and uses this primary pressure air by a booster A equipped with a stop member. Boost the pressure,
The obtained high-pressure secondary pressure air is stored in a high-pressure air storage chamber, and is applied to the striking piston 38 of striking force to drive the piston as required.

The booster A has a drive cylinder 2 with a different inner diameter.
a cylinder 2 integrally formed with a pressure booster cylinder 2b, and a compression piston 3 integrally formed with a drive piston 3a and a pressure booster piston 3b which are slidably housed in each of the cylinders 2a and 2b. , a timing valve 7 and a switching valve 8 are respectively slidably housed in a timing valve chamber 5 and a switching valve chamber 6 formed above the driving cylinder 2a.

The timing valve chamber 5 and the switching valve chamber 6 have an upper feed/exhaust port 16 and a lower supply port 1.
They communicate with each other via 7. Furthermore, the timing valve chamber 5 communicates with the primary pressure air introduction section 18 at the upper part, and the switching valve chamber 6 at the lower part.
communicates with the drive cylinder 2a via the supply/discharge port 19.

Both pistons 3 are installed in the timing valve chamber 5.
Piston rod 1 provided integrally with a and 3b
3 protrudes, and in the direction of the central axis of the rod 13,
An air inflow hole 14 is formed through the air inflow hole 14 . The air inflow hole 14 has an opening 14a at the tip of the piston rod 13, and branches laterally at the top to form an opening 14b. Therefore, a part of the air introduced from the primary pressure air introduction section 18 passes through the side hole 14b, the timing valve chamber 5 and the switching valve chamber 6, and enters the drive cylinder 2a through the supply/discharge port 19. Primary pressure air is supplied to the rear portion of the drive piston 3a, and primary pressure air is supplied from the tip opening 14a of the air inflow hole 14 to the boost cylinder 2b of the boost piston 3b.

Timing valve 7 is piston rod 1
3, is provided with a sealing protrusion 22 on the upper outer circumferential surface, and has an engaging protrusion 2 on the inner side.
3, which operates when the engagement protrusion 23 engages with the protrusions 24, 24a of the piston rod near the vertical dead center during reciprocating movement of the compression piston 3,
The switching valve upper chamber 6a crosses the feed/discharge port 16.
is communicated with the timing valve chamber 5 or the ventilation port 25.

The switching valve chamber 6 communicates with the atmosphere through an exhaust port 20 and an exhaust port 21.

The switching valve 8 fits into the inner wall surface of the switching valve chamber 6 in a sealing manner at the upper part, contacts the inner wall surface and the outer wall surface of the switching valve chamber 6 at the lower part,
Separate.

Next, a stopper piston 10 is housed in a cylinder 9 formed above the booster A as a stop member so as to be movable up and down. The cylinder 9 is formed by disposing a stopper guide 27 on the inner circumferential wall of the primary pressure air introduction part 18, and the stopper piston 10 is formed by a piston part 10a fitted into the cylinder 9 and a stopper guide 27. The stopper part 10b is arranged downward on the coaxial extension of the piston 3 of the booster A, and stops the piston rod 13 before the piston 3 reaches the top dead center. It is set to hit the tip. A through hole 28 is formed in the center of the stopper piston 10, and primary pressure air is sent and discharged from the primary pressure air introducing portion 18 into the cylinder 9 through this through hole 28.

Next, the operation of the booster A having the above configuration will be explained.

When the piston 3 is at the bottom dead center as shown in FIG.
When the piston rods a and 2b are lowered, the upper protrusion 24a of the piston rod 13 engages with the engaging portion 23 of the timing valve 7 near the bottom dead center to lower the valve 7. At this time, the timing valve 7 passes through the supply/discharge port 16 and the switching valve chamber upper chamber 6a.
and the ventilation port 25, the air in the upper chamber 6a is exhausted through the ventilation port 25, and the air in the upper chamber 6a is exhausted through the ventilation port 25.
The internal pressure of is reduced. Correspondingly, the switching valve 8 is pushed up by the air pressure of the driving cylinder 2a acting below the switching valve 8.

When the switching valve 8 rises, the supply path a to the cylinder 2 is cut off, while the drive piston 3a
Since the internal air exhaust path b is opened, the primary pressure acting on the drive piston 3a is released. Therefore, the primary pressure on the primary side only acts on the tip of the piston rod 13. On the other hand, boost cylinder 2
Air inflow hole 1 of piston rod 13 is in b.
Primary pressure air flows in from the tip opening 14a of No. 4 and acts on the tip of the booster piston 3b. Since the pressure increasing piston 3b has a larger effective pressure receiving area at both tips, the piston 3 begins to return due to this area difference, and a return stroke is performed.

During this time, the stopper piston 10 is
It is urged toward the bottom dead center by the action of the primary pressure air introduced inside. During the upward movement of the piston 3, the upper end of the piston rod 13 hits the stopper piston 10, and the upward movement of the piston 3 is braked and temporarily stopped by the resistance thereto (see FIG. 1b).

When the piston 3 rises without resistance, the primary pressure air in the boost cylinder 2b increases as it rises, and the air inlet hole 14 of the piston rod 13 becomes narrower due to the check valve 30. from,
It is difficult to supply large amounts of air. In this way, while the capacity of the primary pressure air in the boosting cylinder 2b gradually increases, the air supply cannot cope with this increase, so the primary air pressure in the boosting cylinder 2b is kept at a predetermined level. The time it takes to reach pressure is
It lags behind when piston 3 reaches top dead center. However, as mentioned above, since the piston 3 hits the stopper piston 10 and is stopped from returning, the internal pressure of the booster cylinder 2b increases during the stoppage, and reaches a level sufficiently close to the source pressure of the primary pressure air. can be reached.

When the internal pressure of the boost cylinder 2b approaches the source pressure of the primary pressure air, the return force exerted by the primary pressure of the boost cylinder 2b on the boost piston 3b becomes greater than the biasing force of the stopper piston, causing the piston 3 to close to the stopper. - It resists the downward force of the piston 10 and continues to rise again, reaching the top dead center.

Piston rod 13 when piston 3 rises again
The lower protrusion 24 engages the engagement protrusion 23 of the timing valve 7 and causes the valve 7 to rise. When the timing valve 7 rises, the supply/exhaust port 1
6, whereby the switching valve chamber upper chamber 6
Communication between a and ventilation port 25 is cut off, and at the same time 1
As the next pressure air enters the upper chamber 6a, the pressing down force of the switching valve 8 is stronger due to the difference in effective pressure receiving area between the upper and lower ends of the switching valve 8 (the upper end is larger than the lower end). The valve 8 is lowered. When the switching valve is lowered, the air supply path a is opened, while the exhaust path b is closed, thereby switching between air supply and exhaustion (see FIG. 1c).

When primary pressure air flows into the drive cylinder 2a, the rear part of the drive piston 3a and the booster piston 3
Air pressure acts on the front part of b, but due to the difference in the effective pressure receiving area, the driving piston 3 has a large effective area.
The pressure acting on point a prevails and the piston 3 is pushed down and returns to the position shown in FIG. At this time, the air in the boost cylinder 2b is compressed and the pressure increases. Air inlet hole 14 of piston rod 13
A check valve 30 is disposed in the tip opening 14a of the
The compressed high-pressure secondary pressure air flows through the air inflow hole 1.
4 cannot be reversed, so boost cylinder 2
The high-pressure air is delivered to the high-pressure air storage chamber B from the secondary-pressure air outlet 12 that is open at the bottom of the air.

When the piston 3 descends, its protrusion 24a engages with the protrusion 23 of the timing valve 7 near the bottom dead center, so the valve 7 descends and when it reaches the bottom dead center, it returns to the position shown in FIG. As shown in FIG. 2, switching between sending and discharging the 1-hour pressure air is prompted by the switching valve 8.

The high-pressure secondary pressure air supplied from the booster 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
5a, high-pressure air in the high-pressure air storage chamber B is introduced through the starting valve mechanism 33, and the head valve 34 is biased downward in the drawing by the action of this high-pressure air pressure. A portion of the lower end surface of the head valve 34 is exposed in the high-pressure air storage chamber B, and an upward biasing force is generated by the action of the high-pressure air in the storage chamber. Due to the difference in the effective area on which the high-pressure air acts, it is kept stationary in the lower position. When the head valve is in this position, the cylinder 37 is open to the atmosphere and the driving air supply port 35 communicating with the high pressure air storage chamber B is blocked. or,
The piston 38 is at the top dead center position, and the driver 39 connected thereto is retracted to an upper position.

Next, after loading the nail 36 into the injection port in the lower part of the main body, the injection port is compacted on the surface of the material to be driven, and when the trigger 32 is further pulled, the starting valve mechanism 33 is activated, thereby causing the head to open. - Cut off the supply of high pressure air to the valve upper chamber 35a and at the same time open the chamber to the atmosphere. As a result, the head valve 34 is moved upward by the action of the high pressure air in the storage chamber acting on the lower surface because the downward biasing force that had been acting on the upper surface of the head valve 34 is eliminated. Due to the upward movement of cylinder 37
At the same time as the driving air supply port 35 formed between the high-pressure air storage chamber B and the high-pressure air storage chamber B is opened, the cylinder 37 is cut off from the atmosphere. High-pressure air in the storage chamber B is instantly and in large quantities supplied into the cylinder 37 from the supply port 35, and the driving piston 38 is driven by this high-pressure air, and the nail 36 is driven by the driver 39 provided on the piston. It is ejected from the injection port and driven into the material to be driven.

When the piston 38 descends, the cylinder 37
Atmospheric air on the lower surface side of the piston 38 inside is removed as the piston 38 descends, and is stored in the piston blowback air reservoir 40. Furthermore, piston 38
After reaching the bottom dead center, the high pressure air on the upper surface side of the piston 38 is directly introduced into the piston blowback air reservoir 40 through a small diameter hole formed in the wall of the cylinder 37 and is stored therein.

After driving the nail 36, by releasing the trigger 32, the high pressure air storage chamber B is released into the head 9 valve upper chamber 35a via the starting valve mechanism 33.
The high-pressure air inside is introduced again, and the biasing force exerted by this high-pressure air on the upper end surface of the head valve causes the head valve 34 to descend, closing the drive air supply port 35 and opening the cylinder 37 to the atmosphere. The piston 38 is connected to the air reservoir 40 for blowing back the piston.
By receiving the internal air pressure on its lower surface, it returns to the top dead center position and prepares for the next driving. In addition,
As the pressure inside the storage chamber decreases due to the consumption of high-pressure air during the driving operation, the above-mentioned booster A is automatically started, and the pressure inside the storage chamber B is maintained at the desired pressure.

As described above, during the return stroke of the piston 3, the stopper piston 10 hits the piston 3 before the switching operation by the timing valve and the switching valve 8 is performed, and its rise is suppressed and delayed. The primary pressure air that has flowed into the small diameter portion 2b of the cylinder 9 is supplied sufficiently close to the supply source pressure, so the amount of secondary pressure air that is pressurized in each compression stroke becomes maximum and flows into the storage chamber B. predetermined 2
The number of times required to store the next pressure can be reduced.

Note that the stopper piston 10 needs to hit the piston 3 before the timing valve 7 and the switching valve 8 cause the switching operation, so in the above example, the piston rod 13 of the piston 3 is the timing valve. It is necessary to hit the rod 13 before engaging 7. However, if the stopper piston 10 hits too close to the front, the reciprocating movement of the piston 3 will become slow and the pressure increase will not be able to handle rapid nail driving. , this contact position may be set.

In addition, the piston portion 1 of the stopper piston 10
The diameter ratio between the piston 0a and the stopper portion 10b may be determined by the diameter ratio between the small diameter portion 3b of the piston and the piston rod 13. That is, during the return stroke of the piston 3, it can be considered that the primary pressure is not acting on the piston driving piston 3a, so the primary pressure acts on the small diameter portion 3b end of the piston 3 and the upper end of the piston rod 13, When the primary pressure air acting on both ends of the piston 3 is equal pressure,
That is, when the air pressure of the primary pressure air flowing into the pressure boosting cylinder 2b reaches the supply source pressure (maximum pressure), it increases due to the pressure difference determined by the pressure receiving effective area ratio (diameter ratio) of the pressure receiving end. On the other hand, stoppa
Since primary pressure (supply source pressure) always acts on the piston 10 at the end 10a of the piston part and the end of the stopper part 10b, a downward biasing force is exerted due to the pressure difference determined by the effective area (diameter ratio) between these ends. It's working. Therefore, the area ratio of the large area portion to the small area portion on which air pressure acts may be set so that the piston 3 is slightly larger than the stopper piston 10. With this setting, the piston 3 that has stopped when it hits the stopper piston 10 cannot rise until the primary pressure air is sufficiently supplied to the boost cylinder 2b and the pressure is close to the original pressure. An effective pressure increase can be obtained in the next compression stroke.

The stop member of the piston 3 is not limited to the stopper piston as described above. FIG. 2 shows an example in which a stopper member 42 supported by a coil spring 41 is attached above the piston 3. The stopper member 42 hits during the return stroke of the piston 3, and its rise is delayed by the spring pressure. . An elastic body such as rubber may be used instead of a spring.

[Brief explanation of drawings]

1a to 1c are longitudinal cross-sectional views of a pneumatic nailing machine equipped with a booster efficiency improvement device according to the present invention and a partially enlarged cross-sectional view showing its operating state, and FIG. 2 is a partially enlarged cross-sectional view showing the booster efficiency It is a sectional view showing other examples of an improvement device. Code, A...booster, B...high pressure air storage chamber,
C...Strike part, 1...Pneumatic nailer, 2,9,
37... Cylinder, 3... Piston, 5... Timing/valve chamber, 6... Switching valve chamber, 7...
...Timing valve, 8...Switching valve, 1
0...Stopper piston (stop member), 10a
...Piston part, 10b...Stopper part, 13...
...Piston rod, 28...through hole.

Claims (1)

[Claims for Utility Model Registration] A booster piston with a small effective pressure receiving area that is slidably housed in a booster cylinder, and a booster piston that is slidably housed in a drive cylinder and integrally connected to the booster piston. a driving piston with a large effective pressure-receiving area; and switching valves that operate in conjunction with the pistons and selectively connect the inside of the driving cylinder to a primary pressure air source and the atmosphere near the upper and lower dead centers of the pistons. , in a booster that boosts the primary pressure air supplied in the booster cylinder to a higher pressure, a stop member that comes into contact with and catches the piston during the return stroke of the booster piston and the driving piston is provided on the piston. A booster characterized in that it is provided with a biasing force in the direction of the bottom dead center, and the biasing force of the stop member is set to be slightly smaller than the return force that primary pressure air acts on the booster piston. efficiency improvement device.