JPH0110451Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a malfunction prevention device for a booster.

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 air 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. 1. 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 flows from the through hole 14a in the piston rod 13 of the boost piston 10 at the top dead center to the diameter difference boost cylinder 2.
0 and acts on the small diameter piston part 11 (small pressure receiving part) of the boost piston 10, while the other part of the primary pressure air is supplied to the timing valve 30 and the switching valve 40 at the top dead center. The air is supplied to the large-diameter cylinder portion 22 through the primary pressure air supply path p opened by the operation of , and acts on the large-diameter piston portion 12 (large pressure receiving portion) within the cylinder portion 22 . At this time, due to the difference in effective area between the two piston parts 11 and 12, the pressure applied to the large-diameter piston part 12 prevails, and 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 51 to a secondary pressure storage chamber (not shown), and is used as driving air for nail driving, etc., if necessary.

By the way, the timing valve 30 is held at the top dead center position by the sliding resistance of the O-rings 32, 33, etc. until just before the booster piston 10 moves downward and reaches the bottom dead center. Immediately before the boost piston 10 reaches the bottom dead center, the engagement convex portion 14 of the boost piston 10 engages with the engagement convex portion 37 of the timing valve 30, and the timing valve 30 is pressed down and operated.
As a result, the switching valve 40 is also operated, the air supply path p is closed and the exhaust path q is opened, air is exhausted from the exhaust path q into the large diameter cylinder section 22, and the pressure of the large diameter cylinder section 22 is reduced. Small diameter cylinder part 21
Since the pressure is increased, the above two piston parts 1
The balance of the working pressures 1 and 12 is reversed, and the booster piston 10 returns to its upward position. Boost piston 1
Timing valve 3 until just before 0 reaches top dead center.
0 is held at the bottom dead center position by sliding resistance such as O-rings 32 and 33. Furthermore, just before the pressure boosting piston 10 reaches the top dead center, the pressure boosting engagement convex portion 15 again engages with the engagement convex portion 37 of the timing valve 30 and operates to push it up. 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.

In this way, the timing valve 30 operates with a delay from the boosting piston 10, and until it engages with the boosting piston 10, it is fitted in the timing valve chamber in a free state, and is simply subjected to the sliding resistance of the O-rings 32, 33, etc. It is merely held in an inactive state by the

However, in a holding mechanism for the timing valve 30 using only sliding resistance such as the O-rings 32 and 33, the timing valve 30 may operate inadvertently due to vibrations during operation of a machine equipped with the above-mentioned booster, for example. Furthermore, when operating at low temperatures, the O-rings 32, 33, etc. contract, reducing sliding resistance, which may result in malfunction.
Furthermore, if the operating speed of the boost piston 10 increases, the timing valve 30 may become unstable to stop, and may operate at the same time as the boost piston 10. This is because when the boost piston 10 moves downward from the top dead center position, the engagement convex portion 15 and the engagement convex portion 37 of the timing valve 30 are in a contacting and engaged state. are integrated, and a difference in effective pressure-receiving area is created above and below the engaging protrusions 15 and 37 in the timing valve 30 chamber, and this area difference (larger in the upper part) causes a downward force to be applied to the timing valve 30. In addition, when the boost piston 10 moves downward, the primary pressure air also flows downward, and this flow action causes a downward force to act on the timing valve 30. . Therefore, despite the sliding resistance of the O-rings 32, 33, etc., the timing valve 30 also moves downward at the same time as the boost piston 10 moves downward. When the timing valve 30 operates, the switching valve 40 also operates, so a malfunction of the timing valve 30 will prompt a malfunction of the switching valve, and the process will be switched before the pressure is increased, which will not only reduce the efficiency of boosting the pressure, but also cause the boost piston to malfunction. 10 may become unstable and the operation may stop.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, and particularly to propose a malfunction prevention device that can prevent malfunction of a timing valve and operate a booster smoothly and reliably.

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 2a, b and c, reference numeral A indicates a booster according to the present invention. In this booster A, the configuration of the boost piston 10 and boost cylinder 20 is as follows:
Although it is substantially the same as that shown in FIG. 1, a plurality of notched grooves 16 are formed in the upper end surface of the engagement convex portion 15 at the lower part of the booster piston 10, as shown in FIG.

Next, the booster A has a timing valve 3.
0 and the switching valve 40 are respectively booster pistons 10.
It is installed on the same axis as shown in the figure so that it can freely reciprocate up and down.

The timing valve 30 is the timing valve chamber 3
1 together with the piston rod 13 of the booster piston 10. The timing valve 30 is formed into a cylindrical shape and is fitted in a timing valve chamber 31 so as to be slidable therein.
A first O-ring 32 is provided around the circumference, and a second O-ring 33 and a third O-ring 34 are provided around the outer wall of the intermediate portion, and between the second O-ring 33 and the third O-ring 34, a switching valve is operated in the outward and outward directions. An air supply hole 35 is formed therethrough. This supply hole 3
The pores 5 are formed small so that only a limited amount of primary pressure air can pass through them per unit time. Further, a through hole 36 is also formed in the lower part of the third O-ring 34.

Further, an engaging convex portion 37 is provided around the inner wall of the timing valve 30, and correspondingly, engaging convex portions 14 and 15 are formed at the upper and lower portions of the piston rod 13, so that the timing valve 30 has the following features: When the piston rod 13 is engaged with the engagement convex portions 14 and 15 on the upper and lower portions thereof, it operates following the piston rod 13. Since the notch groove 16 is formed on the upper end surface of the lower engagement convex portion 15, air can flow through the engagement surface between the engagement convex portion 37 of the timing valve 30 and the lower engagement convex portion 15 of the boost piston 10. A void is formed.

The timing valve chamber 31 is the timing valve 3
As shown in FIG. 3, a holding groove 38 is formed in the inner circumferential wall of the holding groove 38. This holding groove 38 is the timing valve 30
It is formed at a position corresponding to the third O-ring 34 when it is at the top dead center. Therefore, when the timing valve 30 moves upward from the bottom dead center position and reaches the top dead center, the third O-ring 34 is inserted into the holding groove 38.
and is held inactive in that position.
Note that if this holding groove 38 is formed too deep,
Because the engagement with the third O-ring 34 is too strong, when the engagement protrusion 14 on the upper part of the boost piston 10 engages with the engagement protrusion 37 of the timing valve 30, the resistance is too strong when it escapes. I couldn't escape easily, O
The ring may be damaged or the boosting efficiency may decrease.
On the other hand, if the retaining groove 38 is too shallow, the third O-ring 3
4 is too weak to be held in the inoperative state,
As in the past, it operates simultaneously with the boost piston 10. Therefore, it is preferable to form the holding groove 38 to such an extent that such inconvenience does not occur.

The switching valve 40 is also provided coaxially with the boosting piston 10 and the timing valve 30, and is fitted so as to be able to reciprocate up and down in the annular switching valve chamber 41 as shown in the figure. The switching valve chamber 41 has an upper chamber hole 4.
2, 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, an air supply and discharge hole 44 that opens to the large diameter cylinder portion, and an exhaust hole that opens to the exhaust chamber. 45 are formed. Furthermore, the switching valve upper chamber 46
An exhaust port 47 that opens to the atmosphere is formed in the upper part of the exhaust port 47 . The upper chamber hole 42 and the exhaust port 4
7 is formed to such an extent that air can flow smoothly.

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. Then, when the timing valve 30 moves upward and the third O-ring 33 passes through the switching valve upper chamber hole 42, the operating air supply hole 35 forms an operating air supply passage together with the switching valve upper chamber hole 42, Also, the timing valve 30 moves down and the 2nd O
When the ring 33 passes through the switching valve upper chamber hole 42, the operating air supply hole 35 is closed. At this time, the switching valve upper chamber hole 42 and the exhaust port 47 communicate with each other between the first O-ring 31 and the second O-ring 32 to form an operating air exhaust passage. Conversely,
When the operating air supply hole 35 is opened, communication between the switching valve upper chamber hole 42 and the exhaust port 47 is cut off, and the exhaust passage is closed.

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. At this time, the large diameter cylinder portion and the timing valve chamber 31 communicate with each other via the supply/discharge hole 44 and the primary pressure air supply hole 43,
Primary pressure air is supplied to the large diameter cylinder section 22.
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 and
6 is depressurized, and the switching valve 40 moves upward and reaches 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,
12 is reversed, and the boost piston 10 moves upward from the bottom dead center position. In this way, the pressure boosting piston 10 is quickly switched to the pressure boosting process.

Even when the boost piston 10 is moving upward, primary pressure air is supplied from the tip of the small diameter piston section 11 into the small diameter cylinder section 21, but as the boost piston 10 moves upward, the volume of the small diameter cylinder section 21 gradually increases. As a result, the internal pressure of the small diameter cylinder portion 21 becomes smaller than the primary pressure.

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 hole 35 for actuating 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 internal pressure of the upper chamber 46 does not increase easily.
The actuation timing of the switching valve 40 is delayed. For this reason, the speed of upward movement of the pressure boosting piston 10 slows down, and the time for switching to the pressure rising process is delayed, and during that time, primary pressure air continues to be supplied into the small diameter cylinder section 21, so that the internal pressure of the cylinder section 21 is sufficiently maintained at the primary pressure. Approach the pressure.

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.

By the way, when the boost piston 10 is at the top dead center, the timing valve 30 is also at the top dead center position and the engagement between the two continues, so the boost piston 10 and the timing valve 30 are integrated. . However, firstly, the boost piston 1
Since the notch groove 16 is formed in the upper end surface of the lower engagement protrusion 15 of the timing valve 30, the engagement protrusion 37 of the timing valve 30 and the lower engagement protrusion 1 of the boost piston 10
An air circulation gap is formed in the engagement surface with the engagement part 5, so that the difference in effective area between the upper and lower sides of the engagement part is smaller than in the case where the notch groove 16 is not formed, and the air flow resistance is also reduced. . Therefore, the downward force acting on the timing valve 30 is smaller than in the conventional case. Second, when the timing valve 30 reaches top dead center, the third O-ring 3
4 engages with the holding groove 38 of the timing valve chamber 31 and is held in an inoperative state, so even if a downward force acts on the timing valve 30, the timing valve 30 is reliably held at the top dead center. Ru.

The secondary pressure air pressurized as described above is sent to the secondary pressure air storage chamber, and the pressurization process and return process of the pressurizing piston 10 are repeated in the same manner.

As described above, in the booster A, the notch groove 16 is formed in the engagement convex portion 15 of the boost piston 10, and the O-ring retaining groove 38 is formed in the inner wall of the timing valve chamber 31, so that the boost piston 10 is the timing valve 30 in the return process
Even when the timing valve 30 moves upward while being engaged with the piston 10 and reaches the top dead center and switches from the return process to the boost process, the timing valve 30 remains engaged with the boost piston 10 and the timing valve 30.
The timing valve 30 is maintained at the top dead center position despite the difference in area between the upper and lower portions of the engaging portion, the flow effect of the primary pressure air, the reduction in sliding resistance of the O-ring, mechanical vibrations, etc. Therefore, malfunction of the timing valve 30 is reliably prevented.

Note that by providing the notch groove 16 in the engagement convex portion 15 of the boost piston 10, the burden of holding the timing valve 30 due to the engagement between the retaining groove 38 and the O-ring is reduced; however, the notch groove 16 is not necessarily necessary. do not have. Even without this, the retaining groove 38
By the engagement of the O-ring 34 with the O-ring 34, the pressurizing piston 10 can be sufficiently maintained in an inoperative state.
Further, in this regard, the holding groove 38 may be any groove that engages with one or more O-rings of the timing valve 30, and is not limited to one that engages with the third O-ring 34.

Furthermore, the holding mechanism for holding the timing valve in an inoperative state is not limited to the engagement between the engagement groove and the O-ring as shown in the above embodiment, but also the holding mechanism that holds the timing valve in an inoperable state. A mechanism may be used in which the timing valve is held in an inoperative state by magnetic attraction, with the magnet and the other made of a magnetic material.

Furthermore, it goes without saying that the booster having the above structure can be applied not only to nailers but also to other devices that require high pressure.

As explained in detail above, according to the booster malfunction prevention device according to the present invention, the timing valve is held in an inoperative state by the holding mechanism when the boost piston is switched from the return process to the boost process. It is not affected by the difference in effective area between the upper and lower parts caused by engagement with the booster piston, the effect of air flow, the magnitude of sliding resistance of the O-ring, mechanical vibrations, etc., and does not malfunction. Therefore, the pressurization process and return process of the pressurizing piston are repeated and repeated accurately and reliably, and the pressurizer can be operated smoothly.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation outline of a conventional booster, and FIGS. FIG. 3 is an enlarged sectional view showing the state of engagement between the holding groove and the O-ring, and FIG. 4 is an enlarged view of the engagement convex portion of the booster piston. Code A...Booster, 10...Boost piston, 1
3... Piston rod, 20... Differential cylinder,
30...Timing valve, 34...Third O-ring, 40...Switching valve, 38...Retaining groove.

Claims (1)

[Scope of Claim for Utility Model Registration] A pressurization process in which a pressure-boosting piston is actuated by supplying and discharging primary-pressure air supplied from an air supply source to compress a portion of the primary-pressure air and boost the pressure to secondary pressure, and the pressure-boosting process described above. In addition to repeating and continuing the return process of returning the piston, when switching between the two processes, a timing valve that timings the switching of the process near the top and bottom dead center of the boost piston is reciprocated in the timing valve chamber together with the piston rod of the boost piston. In a booster that engages the boost piston with the timing valve to operate the timing valve immediately before the boost piston reaches the top dead center, the boost piston moves from the top dead center to the boost stroke and the timing valve engages with the timing valve. A malfunction prevention device for a booster, comprising a holding mechanism for holding a timing valve in an inoperative state until the timing valve is engaged.