JPH0110452Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a restart device for a booster, and more particularly, to a restart device for restarting a booster that has been boosted to a predetermined pressure after stopping its operation.

Recently, boosters that compress and boost the primary pressure air supplied from an air supply source such as an air compressor to higher-pressure secondary pressure air have been recently installed in nailers that drive nails into hard materials such as steel plates and concrete plates. A system with the following features has been proposed and implemented. As such a pressure booster, for example, a pressure boosting piston having two pressure receiving parts with different effective pressure receiving areas is fitted into a differential cylinder having a large diameter cylinder part and a small diameter cylinder part each having a different inner diameter, and Primary pressure air is supplied to the two pressure receiving sections, and by using the pressure difference based on the effective area difference, the primary pressure acting on the large pressure receiving section compresses the primary pressure air acting on the small pressure receiving section, increasing the pressure to secondary pressure. Repeating the pressure increase process and the return process of reversing the balance of the primary pressure acting on the pressure receiving part by exhausting only the primary pressure air supplied to the large pressure receiving part and returning the pressure boosting piston to its original position. There are things that continue to be done. The outline of its operation is shown in FIG. 1a. First, primary pressure air from an air supply source (not shown) such as an air compressor is introduced through the primary pressure air introduction port 50. A part of this primary pressure air is supplied from the through hole 14a in the piston rod 13 of the boost piston 10 at the top dead center to the small diameter cylinder portion 21 of the boost cylinder 20 via the check valve 16. 11 (small pressure receiving part), while another part of the primary pressure air passes through the primary pressure air supply path p opened by the operation of the timing valve 30 and the switching valve 40 located at the top dead center. The pressure is then supplied to the large diameter cylinder section 22 and acts on the large diameter piston section 12 (large pressure receiving section) within the cylinder section 22 . At this time, due to the difference in effective area between the two piston parts 11 and 12, the large diameter piston part 1
The working pressure against 2 is higher than that of the booster piston 10.
moves downward as shown in the figure. As a result, the primary pressure air in the small diameter cylinder portion 21 is compressed and pressurized by the small diameter piston portion 11 . The boosted primary pressure air is sent from the check valve 25 to the secondary pressure chamber 60, and is used as driving air for nail driving, etc., as required.

Immediately before the boost piston 10 reaches the bottom dead center, the boost piston 10 closes the timing valve 30 as shown in the figure.
Press down to activate. As a result, the switching valve 4
0 is also activated, the air supply path p is closed and the exhaust path q is activated.
is opened, the air inside the large diameter cylinder section 22 is exhausted from the exhaust passage q, and the pressure of the large diameter cylinder section 22 is reduced.
Since the small-diameter cylinder portion 21 is pressurized, the balance of the working pressures on the two piston portions 11 and 12 is reversed, and the pressurizing piston 10 returns to its upward position. Immediately before the boost piston 10 reaches the top dead center, the boost piston 10 pushes up the timing valve 30 again. As a result, the switching valve 40 is operated, the exhaust passage q is closed and the air supply passage p is opened, primary pressure air is supplied to the large diameter cylinder portion 22, and the return process is switched to the pressure increase process. Thereafter, the same operation is repeated.

When operating the switching valve 40, as shown in FIG.
The upper chamber 46 is passed through the opening of the upper chamber hole 42, whereby the upper chamber 46 is connected to the primary pressure air supply hole 52.
Or an operating air supply passage to the upper chamber 46 or the upper chamber 46 by communicating with the exhaust port 47 communicating with the atmosphere.
The switching valve 40 is operated by the differential pressure acting on the upper and lower ends of the switching valve 40 at this time.

However, as the pressure is increased repeatedly as described above, the internal pressure of the secondary pressure chamber 60 gradually becomes high, which is dangerous. A mechanism a is provided. This is usually provided between the exhaust port 47 of the switching valve and the secondary pressure chamber 60,
When the internal pressure of the secondary pressure chamber 60 exceeds a preset pressure, the exhaust passage is closed to stop the operation of the valve, and at the same time, the operation of the timing valve 30 and booster piston is stopped. When the secondary pressure in the secondary pressure chamber 60 becomes lower than the set pressure due to leakage or the like, the exhaust passage of the switching valve 40 is opened and the valve 40 is opened.
The booster is restarted by restarting the timing valve 30 and the boost piston 10.

However, since the booster piston 10 is driven by primary pressure air, if there is sliding resistance when it is reactivated, the driving force and the inoperable holding force due to the above resistance will be balanced at the stop position. Sometimes I put it away. For example, the booster piston 1
0. The timing valve 30 and the switching valve 40 reciprocate in the cylinder and valve chamber in the pressure boosting mechanism to perform operations such as boosting pressure and switching air, and each is surrounded by a plurality of O-rings 17, 33, 49, etc. Therefore, the operation is affected by the sliding resistance of these O-rings. For example, when the boost piston 10 moves upward, it engages with the timing valve 30 near the top dead center to operate it, but if the secondary pressure setting mechanism a operates and the boost piston 10 stops near the top dead center. , and then when restarting,
The timing valve 30 must also be pushed up. At this time, the sliding resistance of not only the O-ring 17 of the boost piston 10 but also the O-ring 33 of the timing valve 30 acts, so that the boost piston 10 may not be able to move upward. Further, when the boost piston 10 pushes up the timing valve 30, one O-ring provided on the timing valve 30 passes through the switching valve upper chamber hole 42 when moving upward, but before that, the secondary pressure setting mechanism a works and the O-ring 33 of the timing valve 30 stops on the upper chamber hole 42, as shown in FIG.
The sliding resistance becomes very large because the two engage in a biting manner, and in addition to this, a leak gap is created for the primary pressure air at the engagement part, resulting in a lack of pressure in the primary pressure air. The piston 10 may become unable to move upward. If the booster is not restarted, the machine equipped with it may become inoperable, or in the case of a nail gun, the nail may be driven incorrectly, or the recoil from the failure may cause bodily injury.

It is an object of the present invention to solve the above-mentioned drawbacks and, in particular, to propose a restart device that can quickly and reliably restart the booster after the operation of the booster has temporarily stopped.

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

In FIGS. 2a, b and c, reference numeral A designates a booster equipped with a restart device according to the present invention. In this booster A, the configuration of the boost piston 10 is almost the same as that shown in FIG.

Next, the boost cylinder 20 and the secondary pressure chamber 60
A check valve 25 is provided between the two, and a leak mechanism for a minute amount of air is also provided. That is, the secondary pressure air outlet 23 and the secondary pressure chamber 60 at the tip of the small diameter cylinder portion 21 of the boost cylinder 20
A valve chamber 24 is provided between the two, and a check valve 25 is disposed within the valve chamber 24. The check valve 25 allows the secondary pressure air in the secondary pressure chamber 60 to
This prevents the current from flowing back to zero. and,
A leak structure 26 is formed on the inner wall sealing surface of the valve chamber 24 that is in contact with the check valve 25 . Third
The figure shows the leak groove 26 from the front.
This leak groove 26 is a groove that allows a minute amount of air to leak, and is not subject to the check action of a check valve. Therefore, a portion of the secondary pressure air sent from the boost cylinder 20 to the secondary pressure chamber 60 flows through the leak groove 26 into the small diameter cylinder portion 2 of the boost cylinder 20.
The air pressure inside the boost cylinder 20 increases due to this back flow.

The timing valve 30 and the switching valve 40 are each provided coaxially with the booster piston 10 so as to be able to reciprocate up and down in the figure.

The timing valve 30 has a piston rod 13 of the booster piston 10 in a timing valve chamber 31.
It is fitted in such a way as to be able to slide freely. This timing valve 30 is formed into a cylindrical shape, and as shown in the figure, a first O-ring 32 is formed on the outer wall of the upper end, and a second O-ring is formed on the outer wall of the middle part.
A ring 33 and a third O-ring 34 are provided, and between the second O-ring 33 and the third O-ring 34, an air supply hole 35 for operating the switching valve is formed penetratingly in the inner and outer directions. The pores of this supply hole 35 are formed small so that only a limited amount of primary pressure air can pass through per unit time. Also, the 3rd O
A through hole 36 is also formed in the lower part of the ring 34.

Further, an engagement protrusion 37 is provided around the inner wall of the timing valve 30, and when the piston rod 13 moves up and down, it engages with the engagement protrusions 14 and 15 on the upper and lower parts of the piston rod 13, and operates by following the piston rod 13. do.

The switching valve 40 is also provided coaxially with the boosting piston 10 and the timing valve 30, and is fitted in a switching valve chamber 41 formed in an annular shape outside the timing valve chamber 31 so as to be vertically movable as shown in the figure. The switching valve chamber 41 includes an upper chamber hole 42, a primary pressure air supply hole 43 that always communicates with the timing valve chamber 31 via the through hole 36 of the timing valve 30, and an air supply/discharge hole that opens into the large diameter cylinder section. 44, and an exhaust hole 45 opening to the exhaust port. Furthermore, an exhaust port 47 that opens to the atmosphere is formed in the upper part of the switching valve upper chamber 46 .

The exhaust port 47 opens to the atmosphere and communicates with the secondary pressure chamber 60 via the secondary pressure setting mechanism a.

The reciprocating movement of the switching valve 40 is controlled by supplying and exhausting air for operating the switching valve into the upper chamber 46. That is, the upper chamber hole 42 communicates with the exhaust port 47 to form an exhaust passage for the air in the upper chamber 46, and the upper chamber hole 42 communicates with the operating air supply hole 35 to form an exhaust passage for the air inside the upper chamber 46. An air supply passage is formed. Whether an exhaust passage or an air supply passage is formed depends on the operation of the timing valve 30. The operating air supply hole 35 of the timing valve 30 is connected to the upper chamber hole 42 when the timing valve 30 moves upward and the second O-ring 33 passes through the upper chamber hole 42 of the switching valve.
Together, they form an operating air supply passage, and are formed in a closed position when the timing valve 30 moves downward and the second O-ring 33 passes through the switching valve upper chamber hole 42. When the operating air supply hole 35 is closed, the switching valve upper chamber hole 42 is connected between the first O-ring 31 and the second O-ring 32.
and the exhaust port 47 communicate with each other to form an exhaust passage, and conversely, when the operating air supply hole 35 opens, the communication between the switching valve upper chamber hole 42 and the exhaust port 47 is cut off, and the exhaust passage is closed. is configured to be

When the operating air supply passage opens and primary pressure air flows from the timing valve chamber 31 into the switching valve upper chamber 46, the switching valve 40 is activated by the air pressure.
moves downward and reaches bottom dead center. Conversely, when the exhaust passage opens, the air in the switching valve upper chamber 46 is exhausted to the atmosphere from the upper chamber hole 42, the pressure in the upper chamber 46 is reduced, and the switching valve 40 moves upward to reach the top dead center.

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

First, when the boosting piston 10 moves downward from the top dead center to a certain position, the engagement protrusion 14 of the piston rod 13 engages the engagement protrusion of the timing valve 30 held at the top dead center position, as shown in FIG. 2a. 37 and moves the timing valve 30 downward until it reaches the bottom dead center. When the timing valve 30 moves downward, the second O-ring 33 passes through the switching valve upper chamber hole 42, so an exhaust passage for the air in the switching valve upper chamber 46 is formed, and the air in the upper chamber 46 is immediately released to the atmosphere. , the pressure in the upper chamber 46 is rapidly reduced, and the working pressure on the upper end of the switching valve 40 is weakened;
Since the primary pressure air of the large-diameter cylinder portion 22 acts on the lower end of the switching valve 40, the working pressure balance between the upper and lower ends is reversed, and the switching valve 40 quickly rises. When the switching valve 40 is raised, the supply/discharge hole 44 and the exhaust hole 45 communicate with each other, as shown in FIG. The working pressure on the large diameter piston portion 12 also gradually decreases. On the other hand, the internal pressure of the small diameter cylinder part 21 increases, and at least the primary pressure is always acting on the tip of the small diameter piston part 11, so these large and small piston parts 11, 1
2 is reversed, and the boost piston 10 moves upward from the bottom dead center position.

When the booster piston 10 moves up to a certain position, the lower engagement protrusion 15 of the piston rod 13 engages with the engagement protrusion 37 of the timing valve 30, which was held at the bottom dead center position, as shown in FIG. Then, the boost piston 10 moves the timing valve 30 upward to reach the top dead center. When the timing valve 30 moves upward, the second O-ring 33 opens the switching valve upper chamber hole 42.
, the exhaust passage is closed and the air supply passage for operating the switching valve is opened instead. As a result, the primary pressure air in the timing valve chamber 31 is supplied into the switching valve chamber 41, and the switching valve 40 is operated by this air pressure.

At this time, since the opening of the operating air supply hole 35 of the timing valve 30 constituting the switching valve operating air supply passage is small, the primary pressure air is supplied to the switching valve upper chamber 46 only little by little. For this reason, the actuation timing of the switching valve 40 is delayed, the speed of upward movement of the booster piston 10 is slowed down, and the time for switching to the boosting process is also delayed, during which time primary pressure air continues to be supplied into the small diameter cylinder portion 21. The internal pressure of the cylinder portion 21 approaches the primary pressure sufficiently.

Thereafter, when the switching valve 40 is operated, the communication between the supply and discharge hole 44 and the exhaust hole 45 is cut off, and instead the supply and discharge hole 44 is communicated with the timing valve chamber 31 via the primary pressure air supply hole 43, and the primary pressure Air is supplied to the large diameter cylinder section 22 and acts on the large diameter piston section 12. Due to the difference in effective pressure receiving area between the large diameter piston part 12 and the small diameter piston part 11, the pressure boosting piston 1
0 moves downward again, and the air inside the small diameter cylinder section 21 is compressed by the small diameter piston section 11 until it reaches the bottom dead center, and the pressure increases. Note that the timing valve 30 is
When the timing valve reaches the top dead center, the third O-ring 34 engages with the holding groove 38 formed in the timing valve chamber 31, as shown in FIG. 2c, so that it is held stationary.

Thereafter, the pressurization process and return process of the pressurizing piston 10 are repeated in the same manner, and the pressurized secondary pressure air is sent to the secondary pressure chamber 60. and,
When the internal pressure of the secondary pressure chamber 60 becomes higher than the set value, the secondary pressure setting mechanism a operates to close the exhaust passage of the switching valve 40 as described above and stop the boosting operation of the booster. Furthermore, the secondary pressure chamber 6
When the 0 internal pressure becomes smaller than the set value, the closure of the exhaust passage is released, and the booster is restarted.

By the way, as mentioned above, due to the operation of the secondary pressure setting mechanism a, the boost piston 10, the timing valve 30, etc. are subjected to a large force to maintain the inoperable state due to the sliding resistance of the O-ring 33, etc., making it difficult to re-operate them. Even if the booster stops at a certain position, the leak mechanism provided between the booster cylinder 20 and the secondary pressure chamber 60 reliably restarts the booster. That is, a leak groove 26 is formed in the sealing surface of the valve chamber 24, and since the leak groove 26 is not subjected to a check action by the check valve 25, the secondary pressure sent from the boost cylinder 20 to the secondary pressure chamber 60 is A part of the compressed air flows from the leak groove 26 to the small diameter cylinder portion 2 of the boost cylinder 20.
It flows back into 1. Since the boost piston 10 is driven by the primary pressure air of the boost cylinder 20, the air pressure of the drive air in the small diameter cylinder portion 21 is equal to that of the secondary pressure air in either state a or b in FIG. When the force increases due to the backflow, the driving force against the booster piston 10 also increases, and it reliably exceeds the inoperative state holding force due to the sliding resistance of the O-ring 33, etc., so the booster piston 10 moves upward. Due to the upward movement of the booster piston 10, the timing valve 30 and the like are also reactivated, and the booster is restarted.

Note that secondary pressure air flows back from the leak groove 26 during the normal pressure increase and return process, but since the leak air is only a small amount, the pressure boost piston 10
is substantially the same as being driven by primary pressure air.

In addition, the booster cylinder 2 is connected from the secondary pressure chamber 60.
The leak mechanism that allows a minute amount of air to flow backwards into the
Not limited to those mentioned above. For example, a configuration may be adopted in which a minute air leak hole (not shown) is formed as a bypass next to the valve chamber 24.

Note that the above-described restart device for a booster is not limited to the secondary pressure setting mechanism, but can also be applied to a case where the booster is restarted after being temporarily stopped using another mechanism. Furthermore, it goes without saying that the booster having the above structure can be applied not only to nailers but also to other machines and devices that require high pressure.

As explained in detail above, according to the booster restart device according to the present invention, when the booster piston is stopped due to the operation of the booster's secondary pressure setting mechanism, etc. A leak mechanism that allows a small amount of air to flow backwards between the boost cylinder and the secondary pressure chamber even if it stops at a position where it is difficult to move upward with only the air pressure of the primary pressure air due to the inoperable state maintaining function. , the air pressure inside the boost cylinder is increased by the secondary pressure air flowing back through the mechanism, and this boost air reliably drives the boost piston, allowing the booster to restart smoothly. .

[Brief explanation of drawings]

Figures 1a and 1b are explanatory diagrams of the operational outline of a conventional booster, and Figures 2a, b, and c are cross-sectional diagrams showing the operating mode of a booster having a restart device according to the present invention, respectively. FIG. 3 is an explanatory diagram of a form of leak groove formation. Code A...Booster, 10...Boost piston, 2
0... Boost cylinder, 25... Check valve, 26...
leak groove.

Claims (1)

[Scope of utility model registration request] Primary pressure air supplied from an air supply source is supplied into a boosting cylinder, and a boosting piston fitted in the boosting cylinder is actuated to compress the primary pressure air in the boosting cylinder and boost the pressure to secondary pressure. In the booster, which repeats and continues a pressure increase step and a return step of returning the boost piston using the primary pressure air in the pressure increase cylinder, and sends the secondary pressure air pressurized in the pressure increase step to the secondary pressure chamber. Restarting a booster characterized by providing a check valve between a boosting cylinder and a secondary pressure chamber and a leak mechanism for leaking a minute amount of air from the secondary pressure chamber to the boosting cylinder. Device.