JPH0615582A - Exhaust silencer of pile driver - Google Patents

Abstract

PURPOSE:To reduce an exhaust noise of compressed air without entailing any drop in the return performance of a piston by way of keeping the cost of a conventional machine intact, in an exhaust silencer of a pile driver using the compressed air as a power source. CONSTITUTION:This silencer is provided with an exhaust port being composed of a lot of almost circular exhaust holes 4 of less than 5mm in each hole diameter, though it has an area necessary for exhausting, and each depth of these exhaust holes 4 is set down to at least more than two times the hole diameter, while a center space of each hole is set down to less than a range from 1.5 to 3 times the hole diameter for compactifying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for a driving machine, which exhausts air consumed by a driving machine which uses compressed air as a power source.

[0002]

2. Description of the Related Art A perspective view of a conventional driving machine is shown in FIG. The driving machine 1 using compressed air as a power source generally has to discharge the compressed air flowing into the upper part of the piston 2 to the outside air during the returning process of the striking piston 2 and becomes an exhaust port which is an outlet of the compressed air. It has a hole 4. This conventional structure has a main body 1
In the exhaust cover 3 described above, several square holes 4 having a required opening area were formed by a die casting mold or the like. In addition, as an exhaust sound deadening structure, there is a structure in which a sponge or a filter having a large number of sintered pores is incorporated in the exhaust port.

[0003]

In the structure shown in FIG. 6,
A sufficient opening area for exhaust can be obtained, and the back pressure generated when the piston 2 returns can be reduced as much as possible, so that a stable normal operation can be obtained. With the increasing density of residential areas in recent years, the influence of exhaust noise generated during the operation of a driving machine on the neighborhood has become a major problem.As a solution to this problem, it is necessary to absorb the exhaust noise in the exhaust port. The number of implanters that have various filters is increasing. However, in this structure, the cost is increased due to the addition of the filter, and since the entire exhaust port is covered with the mesh-like fine holes, the exhaust resistance of the air increases and the return performance of the piston 2 deteriorates. there were. If a filter is added, there is a problem that clogging due to dust in the air or ice in the filter due to cooling of the water around the exhaust port in winter will reduce the exhaust performance during use and reduce the return performance of the piston 2. It was An object of the present invention is to solve the above problems, to secure a stable return performance of a piston, and to reduce noise due to exhaust noise.

[0004]

In order to achieve the above object, in the exhaust port of the driving machine according to the present invention, at least the diameter of the exhaust hole is provided while having an opening area for ensuring the return performance of the striking piston. It is formed by a large number of holes having a substantially circular shape of 5 mm or less, and the depth of the holes is at least twice the hole diameter, and the center distance between the holes is at least 1.5 times to 3 times the hole diameter. It was designed to be densely packed.

[0005]

The exhaust port of the driving machine constructed as described above has a diameter of 5 m while ensuring an opening area for conventional exhaust.
Since the holes with a small diameter of m or less are closely packed, the return performance of the piston is the same as before, but since the air to be exhausted is divided into smaller parts, it is a high level generated at a low frequency compared to exhausting from a large hole. The screech sound, which is apt to become the peak noise of, can be set to 20 KHz or more outside the audible range, and the noise is reduced. Further, by making a large number of holes close to each other, exhaust noise at the central portion is shielded by exhaust gas at the outer periphery, so that noise can be further reduced.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings of one embodiment.

In FIG. 1, the inside of the driving tool main body 1 is composed of a piston 2 for hitting and hitting a stopper (not shown) and a cylinder (not shown) for sliding the piston 2 inward. The exhaust cover 3 of the main body 1 is densely provided with exhaust ports composed of a large number of exhaust holes 4. The opening area of this exhaust port is large enough for the piston 2 to return, and each exhaust hole 4 is formed integrally with the exhaust cover 3 by a die casting or the like. It is desirable that the diameter of the exhaust hole 4 is 2 mm to 5 mm in view of the effect of noise reduction and the life of the mold and the like. FIG. 2 is a model diagram of a Schlieren photograph of an exhaust gas jet in an experiment. From this figure, when the exhaust hole 4 is subdivided and has a diameter of about 5 mm or less, the shock wave interval in the jet decreases in accordance with the hole diameter size, and at the same time, the supersonic flow mixing region in which the shock wave exists in the jet also decreases. You can see that it is shortening. Therefore, the screech sound generated in the low frequency range and becoming a high level noise is outside the high frequency audible range.

Further, in an experiment, when the exhaust holes 4 provided in the exhaust port are closely packed so that the center distance between them is 1.5 times or more and 3 times or less of the diameter, reflection and refraction of sound waves in the shear layer of the jet flow are conducted. It was confirmed that the acoustic shielding effect due to the aeroacoustic interference such as diffraction and the like was obtained, and the noise from the internal jet group with a large number of holes was shielded by the outer jet row and the noise was reduced. However, when the center interval of the exhaust holes 4 is set to 1.5 times or less of the diameter, the separated jets are likely to be mixed again, the above-described sound deadening effect is reduced, and the center interval is set to 3 times or more of the diameter. In the case of, the effect of the shield by the outer jet stream was reduced. According to the actual measurement data of noise in the experiment conducted in consideration of the above results, the noise due to the exhaust has a result that the noise reduction effect of up to 5 dB is obtained as compared with the conventional product.

Next, a driving machine provided with the exhaust hole 4 will be described with reference to FIG. Pull the trigger 6 to pull the head valve 9
When the pressure rises, the air in the pressure accumulating chamber 7 flows into the upper part of the piston 2 and hits the stopper. At this time, the return air chamber 8 also rises due to the air in the pressure accumulating chamber 7, but since the opening area of the exhaust port has the same area as the conventional one, the air above the piston 2 can perform the same exhaustion as the conventional product. Therefore, the return performance of the piston 2 is not deteriorated. Also, since the exhaust hole 4 provided in the exhaust port has a small diameter but a simple shape, clogging due to dust or the like and ice such as drain due to cooling of the exhaust occur as compared with a sound deadening filter such as sponge or a sintered product. do not do.

In the above embodiment, the exhaust cover 3 of the main body 1 is provided with the exhaust port consisting of the plurality of exhaust holes 4, but the same applies to the main body 1 having the exhaust port. It is possible to exert an effect. Figure 4,
FIG. 5 shows another embodiment of the present invention. As shown in FIG. 4, the same effect can be achieved by covering the exhaust port provided with a large number of exhaust holes 4 as a separate piece 10 on the exhaust port integrated with the conventional exhaust cover 3. Further, as shown in FIG. 5, the exhaust cover 3 has an exhaust port including a large number of exhaust holes 4, and the variable exhaust cover 11 is provided outside the exhaust port 4 so that the exhaust direction can be changed. The sound deadening effect can be produced.

[0011]

According to the present invention, since the exhaust port can be integrally formed by die casting or the like as in the conventional case, the exhaust noise can be reduced without increasing the cost. In addition, since clogging such as noise elimination due to conventional filters and the like or icing does not occur, sufficient piston return performance during work can be ensured and operability is improved.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of a driving tool of the present invention.

FIG. 2 is a model diagram of a photograph of an exhaust jet Sirilen by an experiment of the exhaust port of the present invention.

3 is a vertical cross-sectional view of FIG.

FIG. 4 is a partial external perspective view showing another embodiment of the driving tool of the present invention.

FIG. 5 is a partial vertical sectional view showing another embodiment of the driving tool of the present invention.

FIG. 6 is an external perspective view showing an example of a conventional driving machine.

[Explanation of symbols]

Reference numeral 1 is a main body, 2 is a piston, 4 is an exhaust hole, and 5 is a cylinder.

Claims (1)

[Claims] 1. A main body is provided with an exhaust port, which uses compressed air as a power source, drives a stopper by a piston slidably arranged in a cylinder, and discharges the compressed air consumed during the driving process to the outside air. In the driving machine, the exhaust port has a required opening area, is composed of a large number of substantially circular holes each having a hole diameter of at least 5 mm, and has a hole depth of at least twice the hole diameter. An exhaust silencer for a driving machine, characterized in that the center intervals of the holes are made to be 1.5 to 3 times or less the hole diameter so as to be densely packed, and the holes are integrally formed by a die casting mold or the like.