JP4436293B2 - Sound absorption duct for construction machinery - Google Patents

Description

The present invention relates to a sound absorbing duct suitable for an intake port, an exhaust port and the like of an engine room of a construction machine.

In the engine room of construction machines, various devices such as engines, cooling fans, mufflers, heat exchangers such as radiators and oil coolers, hydraulic pumps, and hydraulic valves are installed. These devices generate noise at various frequencies. The engine compartment is covered so that this noise is not released to the outside, and has an intake port and an exhaust port for ventilation. Most of the noise in the engine compartment is released to the outside through the intake and exhaust ports.

In order to reduce the emission of noise, a sound absorbing material is attached to the wall surface in the engine room, and a sound absorbing duct having a sound absorbing material attached to the inner surface is provided at the intake and exhaust ports (see, for example, Patent Document 1).
JP 2002-332659 A (FIGS. 2 and 3)

The conventional construction machine in the form as described above has the following problems to be solved in relation to the sound absorbing duct.

That is, the noise emitted from the engine room is a noise in a wide frequency band from a low frequency of several tens of Hz to a high frequency of several tens of kHz mixed with various frequencies according to measurement by the present inventors.

A known sound absorbing duct has a high low frequency sound absorption coefficient when the length of one side of the cross section is long, and a high frequency sound absorption coefficient when the length of one side is short. Therefore, the cross-sectional shape of the sound absorbing duct is determined so as to absorb and reduce noise in a specific frequency band.

The size of the airframe, such as the engine room of a construction machine, is made as small as possible in order to improve the visibility of the surroundings from the driver and to avoid interference with surrounding obstacles.

Accordingly, it is difficult to prepare various sizes of sound absorbing ducts in a limited size body of a construction machine and absorb and reduce noise in a wide frequency band from low to high frequencies by the sound absorbing ducts.

The present invention has been made in view of the above-mentioned facts, and its technical problem is compactly integrated into a limited-sized body capable of absorbing and reducing noise in a wide frequency band from low frequency to high frequency. It is to provide a sound absorbing duct for construction machinery that can be installed.

As a result of intensive studies and experiments on the shape of the duct, noise absorption, and reduction, the present inventors have developed a sound-absorbing duct that is effective in a wide frequency band and can be compactly integrated.

The invention described in claim 1 includes a duct having a plurality of rectangular cross-section pipes partitioned and extended by a partition wall, and a sound absorbing material attached to the inner surface of each pipe, and has a length in the direction in which the pipes extend. The ducts having different rectangular cross-section sizes are formed in the duct extending direction due to the difference in the length of the partition walls, and the sound absorbing material on the inner surface of each duct has the same length in the duct extending direction. The sound absorbing duct of a construction machine is characterized in that a space is formed between adjacent sound absorbing materials in a portion where no partition wall exists .

And, by changing the depth length of the partition wall that partitions the plurality of pipes in the sound absorbing duct, the pipes having different sizes are formed, and a compact sound absorbing duct that absorbs and reduces noise in a wide frequency band is formed. .

And a sound-absorbing material is prepared also in the part in which a partition does not exist in a duct by the difference in length.

The sound absorbing duct of the construction machine according to claim 1 is provided with rectangular cross-section pipes having different sizes in the duct due to different lengths of the partition walls partitioning the pipe lines, and thus by providing various cross-sectional sizes. It can absorb and reduce noise in a wide frequency band from low frequency to high frequency. Furthermore, since the sound absorption duct can be formed compactly, it is suitable for installation on a limited-sized body.

Since the sound absorbing material attached to the inner surface of each of the ducts of the sound absorbing duct has the same length in the duct extending direction and has a space between adjacent sound absorbing materials in the portion where the partition does not exist, the sound absorbing material The effect of absorbing and reducing noise can be improved by the air layer between the increase in the material and the sound absorbing material.

Hereinafter, a sound absorbing duct of a construction machine configured according to the present invention will be described in more detail with reference to the accompanying drawings illustrating a preferred embodiment.

With reference to FIG. 7, the hydraulic excavator as a construction machine provided with the sound-absorbing duct according to the present invention will be described.

The hydraulic excavator generally indicated by numeral 2 includes a lower traveling body 4 and an upper revolving body 6 that is pivotably mounted on an axis 5 extending vertically on the lower traveling body 4. A driver's cab 8, a work device 10, an engine room 12, and the like are provided.

Various devices such as an engine, a cooling fan, a muffler, a heat exchanger such as a radiator / oil cooler, a hydraulic pump, and a hydraulic valve are installed in the engine room 12. A sound absorbing duct 14 is provided on the side of the engine room 12. An intake port 16 is provided. Outside air is sucked into the engine compartment 12 as cooling air through the intake port 16 by a cooling fan.

The sound absorbing duct 14 will be described with reference to FIG. The sound absorbing duct 14 is formed by stacking a plurality of pipes P having a rectangular cross section with a long side length N and a short side length L, partitioned by a partition wall K, in a row in the direction in which the short side extends (vertical direction in FIG. 1). As a whole, a rectangular parallelepiped duct 18 and a sound absorbing material 20 attached to the inner surfaces of the pipes P are provided.

The duct 18 includes partition walls K (K1 to K3) having different lengths in the extending direction, and pipes P (P1 to P4) having rectangular cross-sections having different sizes formed by the difference in length of the partition walls K. I have.

The sound-absorbing duct 14 in the present embodiment is provided with three types of partition walls K1, K2, and K3 having lengths M1, M2, and M3 in stages, with the length of the partition wall K being between the total length M of the duct 18. The lengths of the partition walls K1 to K3 are between the partition wall K1 and the adjacent outer frame of the duct 18, between the partition walls K1 and K2, between the partition walls K2 and K3, and between the partition wall K3 and the adjacent frame body of the duct 18. A pipe line P1 having a rectangular cross section L × N corresponding to the lengths M1 to M3 is formed, and a pipe line P2 having a rectangular cross section 2L × N is formed by the frame body of the partition wall K2 and the duct 18 due to the difference in length between the partition walls K1 to K3. In the following, a pipe P3 having a rectangular cross section 3L × N and a pipe P4 having a rectangular cross section 4L × N are formed.

The frame body and the partition wall K of the duct 18 are formed of a steel plate. The sound absorbing material 20 is formed of a known material such as urethane foam or glass wool, has the same length M in the direction in which the duct 18 extends, and is attached to the partition wall K and the frame of the duct 18 by being attached thereto. In a portion where the partition wall K does not exist, a space S is formed between the adjacent sound absorbing materials 20.

With reference to FIG. 2, the operation of a known sound absorbing duct will be described first. The sound absorbing duct is composed of a wall material and a sound absorbing material affixed to the wall surface, and the sound in the duct is reflected on the wall material and is absorbed by the sound absorbing material. The specific frequency band F having a high sound absorption effect (transmission loss) has a wavelength of λ (= C / F: C is the speed of sound), and when the length L of one side of the cross section is λ / 2 and λ, the wall surface of the duct Thus, the vibration of the air becomes large, and the transmission loss, that is, the sound absorption effect becomes high when the frequency band F is C / 2L to C / L (Hz).

The operation of the sound absorbing duct 14 will be described with reference to FIG. The sound absorbing duct 14 has different lengths of the partition walls K forming the wall surfaces of the plurality of ducts (pipe lines P) (K1 to K3), so that the size of one side of the rectangular cross section is L, 2L, 3L, 4L. Ducts (ducts P1 to P4) are provided. Therefore, the frequency band F having a high sound absorption effect (transmission loss) is widened from F = C / 2L to C / L (Hz) to F = C / 4L to C / 2L (Hz).

Referring to FIG. 4, the sound absorbing duct 14 further includes a sound absorbing material 20 having the same depth length in a portion where the partition wall K does not exist due to the length of the partition wall K, and between the sound absorbing material 20 and the adjacent sound absorbing material 20. An air layer in the space S is formed between them, and the sound absorption rate at low frequencies is increased by the effect of the air layer between the sound absorbing material and the sound absorbing material, which is a well-known function, and is equivalent to a thick sound absorbing material. The sound absorption effect can be obtained.

The effect of the sound absorbing duct 14 of the construction machine as described above will be described mainly with reference to FIG.

The sound absorbing duct 14 changes the depth length (M1 to M3) of the partition walls K (K1 to K3) partitioning the plurality of pipes P (P1 to P4), so that the partition wall K is present and not present. With a structure in which sound absorbing ducts having different cross-sectional sizes are combined and provided with various cross-sectional sizes of the pipe P, noise in a wide frequency band from low frequencies to high frequencies can be absorbed and reduced. Further, since the sound absorbing duct 14 can be formed compactly, it is suitable for installation on a limited-sized body.

The sound absorbing ducts 14 are arranged in a row with the ducts P having a rectangular cross section arranged in a row, so that the structure is simple and it is easy to install the sound absorbing duct 14 in a limited size body.

Furthermore, by arranging only the sound absorbing material 20 in the air, a sound absorbing effect equivalent to that of a thick sound absorbing material can be obtained by the effect of the air layer, and a higher sound absorbing effect can be obtained.

The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various changes or modifications can be made within the scope of the present invention, for example, as described below. Is.

In the embodiment of the present invention, the sound-absorbing duct 14 includes a plurality of pipes P having different sizes and divided by three partition walls K (K1 to K3) having different lengths. As shown in 5 (a), (b), and (c), the number of partition walls, the depth length thereof, the interval at the frontage, and the like are appropriately changed according to the wave number band that needs to be reduced, the installation space, etc. You may make it form the pipe line of the magnitude | size.

In the embodiment of the present invention, the sound-absorbing duct 14 has the rectangular cross-section pipes P stacked in a line, but as shown in FIG. 6A, a plurality of pipes may be formed vertically and horizontally. Good. Moreover, as shown in FIG.6 (b), you may form the several pipe line from which cross-sectional area differs in the part of the front-and-rear combination frontage with the space | interval of a partition.

BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the sound absorption duct of the construction machine which concerns on this invention is shown, (a) is a perspective view, (b) is sectional drawing. Action explanatory drawing of a sound absorption duct. Action | operation explanatory drawing of the sound absorption duct shown in FIG. The perspective view which shows the relationship between the sound-absorbing material and partition of the sound-absorbing duct shown in FIG. The figure which shows other embodiment (a)-(c) of the sound absorption duct which concerns on this invention. The figure which shows other embodiment (a) (b) of the sound-absorbing duct which concerns on this invention. The side view of the hydraulic shovel which is a typical example of the construction machine equipped with the sound absorption duct of the construction machine which concerns on this invention.

Explanation of symbols

14: Sound absorbing duct 18: Duct 20: Sound absorbing material P (P1 to P4): Pipe line K (K1 to K3): Partition wall S: Space

Claims (1)

A duct having a plurality of rectangular cross-section pipelines partitioned and extended by a partition;
And a sound absorbing material attached to the inner surface of each pipe line,
Including partition walls having different lengths in the direction in which the pipe extends,
Due to the difference in the length of the partition walls, ducts with different rectangular cross-section sizes are formed in the duct extending direction ,
The sound absorbing material on the inner surface of each pipeline has the same length in the direction in which the duct extends,
In the part where the partition does not exist, a space is formed between the adjacent sound absorbing materials ,
A sound absorbing duct for construction machinery.

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