JPH0881976A - Cab for construction equipment - Google Patents

Abstract

PURPOSE: To prevent resonance in a cab, and to reduce the noises of all frequency bands by disposing a metal plate between two hard acoustical boards and mounting each space interrupting layer of a ceiling section and a floor section on a ceiling and a floor so as to cover the ceiling and the floor at intervals. CONSTITUTION: A ceiling-section space interrupting layer 6 is installed to the lower section of a ceiling 78 so as to cover the ceiling 78 at an interval from the ceiling 78. A floor-section space interrupting layer 8 is set up onto a floor 76 so as to cover a rear from the lower section of the sheet 84 of the floor 76 at intervals at that time. Consequently, length H2 in the vertical direction of the internal sound field of a cab 2 is shortened by both space interrupting layers 6, 8, and resonant frequency in the cab 2 is increased to a high-frequency band having a high sound-absorbing effect. The space interrupting layers 6, 8 of a ceiling section and a floor section are fitted by holding metal plates between two hard acoustical boards arranged at intervals respectively, and sound absorption in all frequency bands is ensured. Accordingly, noises in the cab 2 are reduced, and work environment is improved and operating efficiency can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cab of a construction machine such as a hydraulic excavator, and more particularly to a cab with reduced noise.

[0002]

2. Description of the Related Art Referring to FIG. 6, in a hydraulic excavator generally designated by the numeral 50, an upper revolving structure 54 is mounted on a track type traveling device 52 so as to be freely rotatable. A cab 56 is attached to a front portion of the upper swing body 54, and a power unit 58 including an engine, a hydraulic pump and the like (not shown) is attached to a rear portion thereof. The top of the power plant 58 is covered by an enclosure 60. A work machine 62 is also mounted in front of the upper swing body 54. The working machine 62 is the upper swing body 5
4, a boom 64 and an upper revolving structure 54 that are mounted so as to freely rotate.
Hydraulic cylinder 66 provided between the boom 64 and the boom 64 to drive the boom 64, an arm 68 pivotably mounted on the boom 64, and a hydraulic cylinder provided between the boom 64 and the arm 68 to drive the arm 68. 70, arm 68
Bucket 72 and arm 6 rotatably attached to the tip of the
8 and a bucket 72, and a hydraulic cylinder 74 that drives the bucket 72.

In the hydraulic excavator 50, a cab 56 provided for the purpose of ensuring safety when an operator operates a machine, preventing noise, etc., is mounted on the frame of the upper swing body 54 via a vibration isolation member (not shown). Have been installed. Referring to FIG. 5 together with FIG. 6, the cab 56 includes a floor 76, a ceiling 78 formed of a thin plate of a press structure,
Front glass 8 provided between the front ends of floor 76 and ceiling 78
0, and a rear glass 82 provided between the rear end portions of the floor 76 and the ceiling 78. Front glass 80 and rear glass 8
Each of 2 is substantially composed of one piece of glass. Sound absorbing materials 78a and 79a made of urethane foam or the like are attached to the inside of the ceiling 78 and the rear wall 79, respectively. A seat 84 is attached to the floor 76, and an operator 86
Can sit on the seat 84 to operate machines including the work machine 62. The hydraulic excavator 50 can be traveled by the traveling device 52, and the boom 64, the arm 68, and the bucket 72 are driven by the expansion and contraction of the hydraulic cylinders 66, 70, and 74 to perform excavation work and the like. The above-mentioned engine, hydraulic pump, etc. are usually used as the power for these, but the power unit 58 including them generates a large noise during operation, and propagates the noise N to the outside via the enclosure 60. The cab 56 is an operator 8
It plays the role of blocking (preventing) the transmission of noise to the No. 6 unit.

[0004]

The noise N passing through the enclosure 60 reaches the cab 56 and penetrates (transmits) inside. Air naturally exists in the internal space of the cab 56 and has a characteristic as a closed sound field (a region where the progress of sound is restricted). A typical example of this characteristic is a resonance phenomenon (occurrence of muffled sound) in which a region having a high sound pressure and a region having a low sound pressure appear at a specific frequency. When this phenomenon occurs, the noise inside the cab 56 becomes louder than the noise outside the cab 56 in a place where the sound pressure is high, and the noise transmitted to the inside is amplified and adversely affects the operator 86. A more specific description will be given with reference to FIG. FIG. 5 shows the sound pressure distribution in the AA cross section of FIG. At a cross-sectional position passing through the head of the operator 86, a sound pressure mode is generated in the vertical direction. The sound pressure is maximized at the portion of the ceiling 78 and the portion of the floor 76, and the head of the operator 86 seated on the seat 84 is included in the high sound pressure region. In order to absorb the noise that has entered the cab 56, a sound absorbing material 78a or 79a is attached to the inner wall portion. However, the sound pressure mode in the cab 56 is 300H.
Since it occurs in a low frequency range where the sound absorbing effect is Z (Hertz) or less and low, this cannot be sufficiently prevented by the structure in which the sound absorbing material 78a or 79a is attached. Further, due to the size of the cab 56, resonance problems such as matching of the engine ignition frequency and the resonance frequency may occur,
This cannot be sufficiently prevented. On the other hand, the sound absorbing materials 78a and 79a made of urethane foam or the like cannot significantly reduce noise in all frequency bands.
Further, since the rear glass 82 close to the engine has a single glass structure, the noise N from the enclosure 60 cannot be sufficiently blocked. That is, in the conventional cab 56, resonance of the cab cannot be sufficiently prevented, and noise in all frequency bands cannot be sufficiently reduced. As a result, the degree of fatigue of the operator due to noise is great, and the riding comfort and work efficiency are reduced.

It is an object of the present invention to provide an improved cab for construction machinery which can prevent resonance in the cab and can sufficiently reduce noise in all frequency bands.

[0006]

According to the present invention, a floor,
In a cab of a construction machine including a ceiling, a front glass provided between the floor and a front end portion of the ceiling, and a rear glass provided between the floor and a rear end portion of the ceiling, below the ceiling. Is provided with a ceiling space blocking layer so as to cover the ceiling at intervals, and above the floor, a floor space blocking layer is provided so as to cover at least the bottom of the floor and the rear of the floor at intervals. And the ceiling space blocking layer and the floor space blocking layer are
A cab for a construction machine, each of which is composed of two hard sound absorbing plates arranged at intervals and one metal plate arranged at an interval between the hard sound absorbing plates. , Are provided.

[0007]

A ceiling space blocking layer is provided below the ceiling so as to cover the ceiling with a space therebetween, and above the floor, a floor space blocking layer is spaced at least from the lower side of the sheet and behind the floor. It is provided to cover. Therefore, since the ceiling space blocking layer and the floor space blocking layer shorten the vertical length of the internal sound field of the cab, the resonance frequency in the cab is increased to a high frequency range where the sound absorbing material has a high sound absorbing effect. Can be raised to. In other words, it matches the frequency of the sound source,
Resonance can be avoided for the internal sound field in the resonance state. On the other hand, the ceiling space blocking layer and the floor space blocking layer are respectively composed of two hard sound absorbing plates arranged at intervals and one metal plate arranged at a distance between the hard sound absorbing plates. Since it is configured, the sound absorbing effect in the entire frequency range is superior to that of the conventional sound absorbing material (see FIG. 4). Therefore, it is possible to significantly reduce the noise including the muffled sound inside. Further, when the rear glass is made of double glazing, the noise from the enclosure can be blocked more effectively than the single glass, and the noise in the cab can be further reduced. As a result of the noise reduction, the fatigue level of the operator due to noise is significantly alleviated and the riding comfort is greatly improved, so that the working environment of the operator is improved and the working efficiency is significantly improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cab mounted on a construction machine improved according to the present invention, for example, a hydraulic excavator will be described below with reference to FIGS. 1 to 3, parts that are substantially the same as those in FIG. 5 are denoted by the same symbols. The cab, which is generally designated by number 2, includes a floor 76, a ceiling 78, a front glass 80 provided between the floor 76 and the front end of the ceiling 78, and a rear glass provided between the floor 76 and the rear end of the ceiling 78. And glass 4. Below the ceiling 78, the ceiling space blocking layer 6 is provided.
Are provided to cover the ceiling 78 at intervals. Above the floor 76, the floor space blocking layer 8 is provided so as to cover at least a rear portion of the floor 76 from below the sheet 84 at a distance. The ceiling space barrier layer 6 is a horizontal portion 6a extending substantially horizontally and at intervals along the ceiling 78.
And a front end portion 6b extending from the horizontal portion 6a toward the ceiling 78. The floor space blocking layer 8 is a sheet 8
4, a horizontal portion 8a extending substantially horizontally and at a distance along the floor 76, an inclined portion 8b extending from the horizontal portion 8a toward the lower side of the rear glass 4, and a rear wall further extending from the inclined portion 8b. Rear end portion 8 extending toward 79
c and a front end portion 8d extending from the horizontal portion 8a toward the floor 76. As shown in FIG. 2, the ceiling space blocking layer 6 (and the floor space blocking layer 8) includes two hard sound absorbing plates 10 and 12 arranged at intervals, and the hard sound absorbing plates 10 and 12. It is composed of one metal plate (reflecting plate) 14 which is arranged with a space therebetween. The hard sound absorbing plates 10 and 12 are made of, for example, sound absorbing plastic, rock wool or the like, and the metal plate 14 is made of, for example, a steel plate or a lead plate. These hard sound absorbing plates 10 and 12 and the metal plate 14
And are integrally held so as to form an air layer through a spacer (not shown). The ceiling space blocking layer 6 and the floor space blocking layer 8 thus configured are respectively fixed to the ceiling 78 and the floor 76 by fasteners such as bolts (not shown). As a result, as shown in FIG.
A space blocking layer is formed in an upper portion and a lower portion (closer to the rear) with respect to the outer dimension of the cab 2 indicated by a two-dot chain line. The rear glass 4 is composed of double glass, that is, two glasses 16 arranged at intervals in the front-rear direction.

Referring again to FIG. 5, when the hydraulic excavator 50 is in operation, when a characteristic resonance (muffled sound) as shown in FIG. 5 occurs, the resonance frequency f (HZ) of the resonance frequency f c (m / s) and the vertical length of the internal sound field (distance between the floor 76 and the ceiling 78) are H1 (m), they are expressed by the following equation. f = c / (2H)

In the present invention, as is clear from a comparison between FIG. 1 and FIG. 5, the ceiling space blocking layer 6 and the floor space blocking layer 8 are provided, whereby the vertical length of the internal sound field is increased. H2 (m), which is shorter than H1 (the distance between the hard sound absorbing plate 10 located below the ceiling space blocking layer 6 and the hard sound absorbing plate 12 located above the floor space blocking layer 8)
Has been reduced to. Therefore, the resonance frequency in the cab 2 can be increased to a high frequency range where the sound absorbing effect of the sound absorbing material is high. In other words, resonance can be avoided for the internal sound field that is in resonance with the frequency of the sound source. On the other hand, the ceiling space blocking layer 6 and the floor space blocking layer 8 respectively include two hard sound absorbing plates 10 and 12 and a plurality of hard sound absorbing plates 10 and 12 arranged at intervals.
Since it is composed of one sheet of metal plate 14 disposed with a space (air layer) between it and, that is, it is composed of a hard sound absorbing plate having an air layer, the conventional sound absorbing material 78a. And 79a, the sound absorbing effect is significantly improved, and the sound absorbing effect in the entire frequency range is excellent (see FIG. 4). Therefore, it is possible to significantly reduce the noise including the muffled sound inside. Further, since the noise source 18 such as the air conditioner mounted on the floor 76 is covered by the floor space blocking layer 8, it is effectively prevented from absorbing sound and propagating to the space where the operator 86 exists. It Further, when the rear glass 4 is composed of the double glass 4 composed of the two glasses 16 arranged at a distance,
It is possible to sufficiently block the noise from the enclosure 60 and to further reduce the noise in the cab 2 as compared with the case of using one piece of glass. As a result of the noise reduction, the degree of fatigue of the operator 86 due to noise is significantly alleviated and the riding comfort is greatly improved, so that the working environment of the operator 86 is improved and the working efficiency is significantly improved.

[0011]

According to the cab of the construction machine constructed according to the present invention, resonance in the cab can be prevented and noise in the entire frequency band can be sufficiently reduced. as a result,
The degree of fatigue of the operator due to noise is greatly alleviated, and the riding comfort is greatly improved, so that the working environment of the operator is improved and the working efficiency is significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a cab of a construction machine improved according to the present invention.

FIG. 2 is an enlarged sectional view of a B part of FIG.

FIG. 3 is a schematic perspective view showing a main part of the cab shown in FIG. 1 in a see-through manner.

FIG. 4 is a diagram comparing the sound absorbing effect between a hard sound absorbing plate having an air layer in the present invention and a conventional sound absorbing material.

FIG. 5 is a schematic cross-sectional view showing a conventional cab.

6 is a side view of a hydraulic excavator including the cab shown in FIG.

[Explanation of symbols]

 2 Cab 4 Rear glass 6 Ceiling space barrier layer 8 Floor space barrier layer 10 and 12 Hard sound absorbing plate 14 Metal plate 16 Glass 60 Enclosure 76 Floor 78 Ceiling 80 Front glass 86 Operator H1 and H2 Vertical length of internal sound field N noise

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masataka Kawaguchi 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (2)

[Claims] 1. A construction machine comprising a floor, a ceiling, a front glass provided between the floor and a front end portion of the ceiling, and a rear glass provided between the floor and a rear end portion of the ceiling. In the cab, a ceiling space blocking layer is provided below the ceiling so as to cover the ceiling at intervals, and a floor space blocking layer is provided above the floor from at least below the seat to the rear of the floor. The ceiling space blocking layer and the floor space blocking layer are respectively provided with a space between the two hard sound absorbing plates and the hard sound absorbing plate. A cab for a construction machine, characterized in that the cab of the construction machine is composed of a single metal plate that is arranged. 2. The cab of a construction machine according to claim 1, wherein the rear glass is made of double glazing.