JPH0223831Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a control valve for a booster that obtains high-pressure driving air by compressing and increasing the pressure of primary pressure air supplied from the outside.

(Prior art and its problems) A booster that compresses and boosts the primary pressure supplied from an external air supply source such as an air compressor to a higher secondary pressure is used, for example, for concrete nailing, which requires a strong striking force. By incorporating it into a pneumatically actuated nailer, etc., it is possible to obtain the necessary driving air without using a large air compressor, so its development is desired. , a booster shown in FIG. 2 has been proposed.

That is, this booster A' has a housing 61
A valve chamber 62 and a cylinder 63 having different inner diameters are formed inside, the valve chamber 62 is opened to the primary pressure side, the cylinder 63 is opened to the secondary pressure side, and a compression piston 64 having a different outer diameter is fitted inside the cylinder 63. A cylindrical switching timing valve 65 is fitted into the valve chamber 62 coaxially with the compression piston 64, and a piston rod 66 of the compression piston 64 projects into the valve chamber 62.
At the center of the piston rod 66 is an air inflow hole 67.
is formed through the inflow hole 67, and the inflow hole 67 is provided with a side opening 67a that branches in the middle and communicates with the valve chamber 62. The switching timing valve 65 is disposed to fit into the piston rod 66, and a protrusion 68 at its upper end engages with the engaging portions 66a, 66 of the rod 66.
When engaged with b, it operates following the movement,
At this time, the seal protrusion 69 provided on the outer surface
The cylinder 63 is communicated with the valve chamber 62 or the atmosphere by passing over the opening 70a of the next pressure air supply/discharge port 70. Further, the valve chamber 62 has an exhaust port 71
It communicates with the atmosphere through an air supply and exhaust port 70, and communicates with the cylinder large diameter portion 63a through an air supply and exhaust port 70. The compression piston 64 has an air inlet hole 67 in the piston rod 66.
While primary pressure air is continuously supplied from the tip opening 67a to the front part of the piston small diameter part 64b in the cylinder small diameter part 63b, to the rear part of the piston large diameter part 64a in the cylinder large diameter part 63a, By supplying primary pressure air from the tip of the side opening 67a of the inflow hole 67 and exhausting this air from the exhaust port 71, the small diameter portion 64b and the large diameter portion
The switching timing valve 65 is driven by the pressure difference between the primary pressure air which acts reversibly on the switching timing valve 65
is used to switch the above-mentioned supply and discharge.

Briefly explaining the operation of the booster A', when the compression piston 64 is near the bottom dead center, the valve chamber 62 below the switching timing valve 65 communicates with the primary pressure air supply/discharge port 70. Primary pressure air is supplied from the valve chamber 62 to the cylinder large diameter portion 63a, and when the compression piston 64 descends, the protrusion 68 of the switching timing valve 65 engages with the piston rod engaging portion 66a, causing the valve 65 to engage with the piston rod engaging portion 66a.
5 is pushed down, whereby the seal protrusion 69 passes through the supply/discharge port opening 70a, the air supply path is cut off, and the primary pressure air supply/discharge port 7
0 and the exhaust port 71 communicate with each other, supply and discharge of primary pressure air is switched, the primary pressure air in the cylinder large diameter portion 63a is exhausted, and the pressure of the cylinder 63a is reduced. Therefore, the primary pressure acts on the rear end of the piston rod 66 and the piston small diameter portion 64b, and the compression piston 64 rises due to the pressure difference based on the difference in effective pressure receiving area between the two. compression piston 64
Just before reaching top dead center, piston rod 6
The lower end engaging portion 66b of the switching timing valve 65 engages with the engaging portion 68 of the switching timing valve 65, and the valve 65 is pushed up, whereby the seal protrusion 69 passes through the supply/discharge port opening 70a again, and the above-mentioned The exhaust path is shut off, and the valve chamber 62 and the primary pressure air supply/discharge port 70 communicate with each other to switch the supply/discharge of the primary pressure air, and the primary pressure air flows into the cylinder large diameter portion 63a. Cylinder large diameter part 63a and cylinder small diameter part 6
3b is supplied with primary pressure air of approximately the same pressure,
Since the effective pressure-receiving area of the piston large-diameter portion 64a is larger than the effective pressure-receiving area of the piston small-diameter portion 64b, the compression piston 64 descends again. On this occasion,
The primary pressure air within the cylinder small diameter portion 63b is compressed and increased in pressure, and is sent out as high pressure driving air from the end opening 72 of the booster A'.

However, in the above configuration, when supplying and discharging primary pressure air, the switching timing valve 65 moves up and down and passes through the opening 70a of the primary pressure air supply and discharge port 70 that opens on the inner wall of the valve chamber 62.
At this time, a phenomenon occurs in which the seal protrusion 69 of the valve 65 instantaneously closes the opening 70a. As a result, during the compression stroke, the supply path of primary pressure air that drives the compression piston 64 is cut off, and during the return stroke, the exhaust path that discharges the air acting on the compression piston 64 to the atmosphere is cut off. Even in this case, the inside of the drive-side cylinder 63a of the compression piston 64 is in a sealed state, so the forces acting on both ends of the compression piston are in a balanced state, and the compression piston is not driven. Therefore, this has been an obstacle to stable operation of the booster.

In response to this, attempts have been made to create boosters that operate stably, but these have had problems in that they are complicated in structure and have to be large.

(Problem to be solved by the invention) The technical problem of the invention is to solve the above-mentioned problems and to propose a control valve for a booster that operates stably and can be made smaller and lighter. do.

(Means for Solving the Problems) In order to solve the above problems, a control valve for a booster according to the present invention includes a boost piston with a small effective pressure-receiving area that is slidably housed in a boost cylinder;
a driving piston having a large effective pressure receiving area, which is slidably housed in a driving cylinder that is continuous with the boosting cylinder and is integrally connected to the boosting piston, and which supplies primary pressure air from a primary pressure air source. is constantly supplied into the boosting cylinder through a check valve, and by repeating the introduction and discharge of primary pressure air to the drive cylinder, the primary pressure air in the boosting cylinder is boosted to a higher pressure. In the booster, a valve chamber is formed on the axial extension of the drive cylinder, and a piston rod common to the boost piston and the drive piston is extended and disposed within the valve chamber, and the upper and lower dead centers of both the pistons are A timing valve that is operated by the piston rod and selectively connects the valve chamber to a primary pressure air source and the atmosphere is slidably accommodated in the vicinity, while another annular valve is provided on the outer circumferential side of the timing valve. chambers are formed concentrically, and a switching valve is slidably housed in the valve chamber for selectively connecting the inside of the drive cylinder to the primary pressure air source and the atmosphere when activated in accordance with the selective connection by the timing valve. It is characterized by

(Effect of the invention) As described above, according to the invention, the introduction and discharge of primary pressure air into the drive cylinder is directly controlled by the switching valve, but the switching operation of the switching valve is is performed based on the operation of the timing valve. The operation of the timing valve is performed near the top and bottom dead centers of both pistons, and at this time, the introduction and discharge of air into and out of the drive cylinder are close to their limits. Control of introduction and discharge of secondary pressure air is hardly affected. Therefore, both pistons operate stably and smoothly.

In addition, in the present invention, a valve chamber is formed on the extension of the drive cylinder, a piston rod common to the booster piston and the drive piston is extended and arranged in this valve chamber, a timing valve is provided, and the outer periphery of the valve chamber is provided with a timing valve. It has a structure in which an annular switching valve chamber is arranged concentrically on the side, and the booster piston, driving piston, timing valve, and switching valve are arranged on the same axis, making it lightweight,
A compact booster can be constructed, and therefore a tool incorporating the booster can be made lighter and smaller.

(Example) Hereinafter, an example of a control valve for a booster according to the present invention built into a pneumatic nailing machine will be described with reference to FIGS. 1a, b, and c.

In the figure, the symbol N indicates a pneumatic nailing machine with a built-in booster. This pneumatic nailing machine N supplies air from a primary pressure air source (not shown) such as an air compressor through an air introduction hole 10, increases the pressure in a booster A, and generates the high pressure obtained. Secondary pressure air is stored in the high-pressure air storage chamber 7 and acts on the striking piston 40 of the striking part B to drive the piston 40 as required.

The booster A has a cylinder 1 formed integrally with a drive cylinder 1a with a large inner diameter and a boost cylinder 1b with a small inner diameter, and a cylinder 1 with an effective pressure receiving area that is slidably accommodated in the drive cylinder 1a and the boost cylinder 1b, respectively. A piston 3 is formed by integrally combining a large drive piston 3a and a booster piston 3b with a small effective pressure receiving area, and a timing valve chamber 2a provided on an axial extension of the drive cylinder 3a and concentric with its outer peripheral side. a timing valve 4 and a switching valve 5 slidably housed in the valve chambers 2a and 2b, respectively; and the driving piston 3a.
and a piston rod 6 which is provided in common with the booster piston 3b and is disposed within the timing valve chamber 2a.

The valve chambers 2a and 2b are provided in the upper part of the cylinder 1 and coaxially with the cylinder 1, and are a timing valve chamber 2a and a switching valve chamber that communicate with each other via an upper feeding/discharging port 24 and a lower supply port 41. 2b.

The timing valve chamber 2a is the primary pressure air introduction part 1
0a, a piston rod 6 is arranged in the center thereof, and a timing valve 4 is housed in the outer periphery of the piston rod 6.

The piston rod 6 has engaging parts 16 and 1 at the upper and lower parts.
7 is formed protrudingly, and an air inflow hole 11 is formed through the center. A side hole 11a is branched in the middle of the air inflow hole 11, and a check valve 2 is installed at the tip.
9 is provided. Therefore, the primary pressure air in the air introduction section 10a is constantly supplied into the pressure boosting cylinder 1b from the check valve 29 via the air inflow hole 11.

The timing valve 4 is formed with an engaging protrusion 15 that engages with the engaging parts 16 and 17 of the piston rod 6 near the vertical dead center of the piston 3, and a seal protrusion 14 is formed on the outer periphery. Then, when the seal protrusion 14 is actuated by the engagement and passes through the feed/discharge port 24, the switching valve chamber 2b is activated.
The upper chamber 48 is selectively connected to the timing valve chamber 2a and the intake/exhaust port 19 communicating with the atmosphere.

Next, the switching valve chamber 2b has an exhaust port 25,
It communicates with the atmosphere through the exhaust port 25a, and communicates with the cylinder 1 through the supply/discharge port 27.
A cylindrical switching valve 5 is housed inside the switching valve chamber 2b so as to be vertically slidable.

The switching valve 5 has an upper large diameter part 5a and a lower small diameter part 5c smaller than the large diameter part 5a. By sliding the switching valve chamber 2b upward, the primary pressure supply port 41 and the supply/discharge port 27 are communicated, and the primary pressure air is transferred to the timing valve chamber 2b.
The air supply path a from a to the drive cylinder 3a is opened, and the exhaust path b, which communicates with the exhaust port 25 and the supply/discharge port 27 and between the drive cylinder 1a and the atmosphere, is closed. Further, by sliding downward, the exhaust passage a is closed, while the exhaust passage b is opened.
That is, the switching valve 5 selectively connects the drive cylinder 1a to the primary pressure air and the atmosphere.

The switching operation of the switching valve 5 is performed based on the selective connection operation of the timing valve 4, as will be described later.

Next, 45 is a stopper piston, and this stopper piston 45 is housed in a cylinder 43 formed above the booster A so as to be able to move up and down. A hole 44 is formed. The stopper section 45a is connected to the booster A.
is arranged downwardly on the coaxial extension of the piston 3,
It is set so that the piston 3 hits the tip of the piston rod 6 before reaching the top dead center.

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. , engages with the engagement protrusion 15 of the timing valve chamber 4 near the bottom dead center, and operates it downward. At this time, timing valve 4
passes through the supply and discharge port 24 to communicate the switching valve chamber upper chamber 48 and the suction and discharge port 19, and the upper chamber 48
Since the air inside is exhausted to the atmosphere through the suction/exhaust port 19, the internal pressure of the upper chamber 48 is reduced. Correspondingly, the switching valve 5 is pushed up by the air pressure of the driving cylinder 1a acting on the lower end of the switching valve 5 (FIG. 1b).

When the switching valve 5 rises, the supply path a to the cylinder 1 is cut off, while the drive cylinder 1a
Since the internal air exhaust path b is opened, the primary pressure acting on the drive cylinder 1a is released. Therefore, the primary pressure on the primary side only acts on the tip of the piston rod 6. On the other hand, the boost cylinder 1b
Primary pressure air flows into the piston from the opening at the tip of the air inflow hole 11 of the piston rod 6 and acts on the tip of the booster piston 3b. Since the pressure-receiving effective area of both tips is larger in the booster piston 3b, this area difference causes the piston 3 to move to the return stroke.

During the upward movement of the piston 3, the upper end of the piston rod 6 hits the stopper piston 45, and this resistance temporarily stops the upward movement of the piston 3, thereby delaying its return. During the stop, a sufficient amount of primary pressure air is supplied, and the internal pressure of the booster cylinder 1b increases, and can reach sufficiently close to the original pressure of the primary pressure air.

When the internal pressure in the small diameter portion of the cylinder approaches the original pressure of the primary pressure air, the piston 3 continues to rise again against the downward force of the stopper piston 45 and reaches the top dead center. When the piston 3 rises again, the engaging portion 17 of the piston rod engages the engaging protrusion 1 of the timing valve 4.
5 and raises the valve 4. The timing valve 4 passes through the supply/discharge port 24 when rising, thereby cutting off communication between the switching valve chamber upper chamber 48 and the suction/discharge port 19, and at the same time, primary pressure air flows into the upper chamber 48. be introduced. When primary pressure air enters the upper chamber 48 of the switching valve chamber, the effective pressure receiving area difference between the upper and lower ends of the switching valve 5 (large diameter portion 5a
is larger than the medium and small diameter portions 5b and 5c), the downward force of the switching valve 5 is stronger, and the valve 5 is lowered. When the switching valve 5 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 air flows into the drive cylinder 1a,
Air pressure acts on the rear part of the drive piston 3a and the front part of the boost piston 3b, but due to the difference in pressure receiving area, the pressure that acts on the drive piston 3a (large pressure receiving part) with a larger effective area is higher than the pressure on the boost piston 3b.
The compression piston 3 is pushed down by the pressure acting on the small pressure receiving portion and returns to the position shown in FIG. 1a. At this time, the air in the boost cylinder 1a is compressed and the pressure increases. Since the high-pressure secondary air boosted by the check valve 29 at the tip opening of the air inflow hole 11 of the piston rod 6 cannot flow back through the air inflow hole 11, the high pressure secondary air 2 is opened at the bottom of the boost piston 3b. The secondary pressure air is sent to the high pressure air storage chamber 7 from the next pressure air delivery port 30 . When the compression piston 3 is lowered, the engaging portion 16 is engaged with the engaging protrusion 15 of the timing valve 4 near the bottom dead center to lower the valve 4, and when the valve 4 reaches the bottom dead center, again as shown in FIG. As shown in a, switching of supply and discharge of the primary pressure air by the switching valve 5 is prompted.

The high-pressure secondary pressure air supplied from the booster A having the above configuration to the high-pressure air storage chamber 7 is used as driving air for nail driving as required. Next, this will be briefly explained.

First, before driving, the head valve upper chamber 56
High pressure air in the high pressure air storage chamber 7 is introduced to the start valve mechanism 54, and the head valve 55 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 55 is exposed in the high-pressure air storage chamber 7 and generates an upward biasing force due to the action of the high-pressure air in the storage chamber. It is kept at the lower position due to the difference in the effective area on which it acts. At the head valve position, the cylinder 58 is open to the atmosphere, and the driving air supply port 57 communicating with the high pressure air storage chamber 7 is blocked. Also, the striking piston 40
is at the top dead center position and the driver 5 connected to it
9 has been retracted to the upper position.

Next, after loading the nail 52 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 53 is further pulled, the starting valve mechanism 54 is activated, thereby causing the head valve to open. At the same time as cutting off the supply of high pressure air to the upper chamber 56, the chamber 56 is opened to the atmosphere. As a result, the downward biasing force acting on the upper surface of the head valve 55 is eliminated, and the head valve 55 is moved upward by the action of the high pressure air in the storage chamber 7 acting on the lower surface. Due to the upward movement, the driving air supply port 57 formed between the cylinder 58 and the high-pressure air storage chamber 7 is opened, and at the same time, the cylinder 58 is isolated from the atmosphere. High-pressure air in the storage chamber 7 is instantly and in large quantities supplied into the cylinder 58 from the supply port 57, and the driving impact piston 40 is driven by this high-pressure air, and the driver 59 provided on the impact piston 40 drives the nail. 52 is ejected from the injection port and driven into the material to be driven.

When the striking piston 40 descends, the atmosphere on the lower surface side of the striking piston 40 in the cylinder 58 is removed as the striking piston 40 descends, and a part of the air is removed through the large diameter hole 61 formed in the wall of the cylinder 58. The piston blowback air is introduced into the piston blowback air storage 60 and stored therein. Further, after the striking piston 40 reaches the bottom dead center position, the high pressure air on the upper surface side of the striking piston 40 is directly introduced into the piston blowback air reservoir 60 through the small diameter hole 62 and stored therein.

After driving the nail 52, by releasing the trigger 53, the high pressure air in the high pressure air storage chamber 7 is reintroduced into the head valve upper chamber 56 via the starting valve mechanism 54, and this high pressure air is supplied to the head valve. The head valve 55 is lowered by the biasing force acting on the upper end, closing the driving air supply port 57 and opening the cylinder 58 to the atmosphere. The striking piston 40 returns to the top dead center position by receiving the air pressure in the piston blow-back air reservoir 60 on its lower surface, and is ready for the next driving. Note that, due to a decrease in the pressure inside the storage chamber due to the consumption of high-pressure air during the driving operation, the above-mentioned booster A is automatically started to maintain the pressure inside the storage chamber 7 at the desired pressure.

As described above, according to the booster A, switching control of the supply from the primary pressure air introduction hole 10 to the drive cylinder 1a and the exhaust from the cylinder 1a is controlled by the cooperation of the timing valve 4 and the switching valve 5. Therefore, the timing valve 4 starts operating near the vertical dead center of the compression piston 3, which is the timing for switching the supply and discharge of primary pressure air, and switches the switching valve 5. Direct switching of primary pressure air supply and exhaust is performed instantaneously and reliably by the switching valve 5, and the timing valve chamber 4 is connected to the supply and exhaust port 2.
4 and occluding the port 24. That is, the timing valve 4 passes through the supply/discharge port 24 when the switching valve 5 is at the upper end or the lower end and the air supply path a or exhaust route b is opened to the maximum. Even if 24 is temporarily closed, air supply and discharge are not affected in any way. Therefore, the compression piston 3 reciprocates stably and smoothly.

Furthermore, in the illustrated example, the timing valve and the switching valve are provided coaxially with the compression piston, so the booster can be configured to be lightweight and compact.

[Brief explanation of drawings]

Figures 1a, b, and c are a cross-sectional view of an example of a timing valve and a switching valve of a booster according to the present invention installed in a pneumatic nailer, and a partially enlarged cross-sectional view showing the operating state thereof, respectively. 2 is a sectional view of a conventional booster. Code A...Booster, 1...Cylinder, 1a...
Drive cylinder, 1b... Boost cylinder, 2a...
Timing valve chamber, 2b...Switching valve chamber,
3... Piston, 3a... Drive piston, 3b...
...boosting piston, 4...timing valve, 5...
...Switching valve, 6...Piston rod, 29...
...Check valve, 48...Upper chamber.

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 that is continuous with the booster cylinder and that is connected to the booster piston. It is equipped with an integrally connected drive piston with a large effective pressure receiving area, and constantly supplies primary pressure air from a primary pressure air source into the pressure boosting cylinder via a check valve, and also provides a primary pressure air supply to the drive cylinder. In a booster that increases the pressure of primary pressure air in the boost cylinder to a higher pressure by repeating the introduction and discharge of pressurized air, a valve chamber is formed on an axial extension of the drive cylinder, and A piston rod common to the booster piston and the drive piston is extended in the valve chamber, and is actuated by the piston rod near the upper and lower dead centers of both pistons to connect the primary pressure air source and the atmosphere to the valve chamber. A timing valve to be selectively connected to the timing valve is slidably housed therein, and another annular valve chamber is concentrically formed on the outer circumferential side of the timing valve. A control valve for a booster, characterized in that a switching valve is slidably housed to selectively connect the inside of the drive cylinder to a primary pressure air source and the atmosphere.