JP2003268805A - Driver's cab structure of construction machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the habitability of a driver's cab by reducing a blurred sound in the driver's cab. <P>SOLUTION: In the hydraulic backhoe, a sound deadening hole 40 letting the full sound in a cabin 9 resulting from the operation of an engine escape is formed to a pillar 94 in a peripheral wall constituting the cabin 9 in a structure in which an engine room 10, on which the engine is loaded, and the box- shaped cabin 9 are installed on a revolving frame 8. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cab structure of a construction machine, and is suitable for a narrow cab structure of a construction machine such as a small hydraulic excavator.

[0002]

2. Description of the Related Art In recent years, construction machines such as small hydraulic excavators are often provided with a cabin (driver's cab) in consideration of the habitability of the driver. This cabin is
It has a substantially sealed structure exclusively for the purpose of isolating the driver from noise, etc. when the engine is operating in the middle or high speeds.

[0003]

However, in the cabin having the substantially closed structure, the driver may have a so-called "comfortable feeling" when the engine is idling or the like at a low rotation speed, which adversely affects the habitability of the driver. May be given.

"Muffled feeling" means a feeling that a human eardrum is pressed by a sound pressure component having a high degree of prominence in a low frequency range, and that the low frequency peak has a high degree of excellence in the cabin. It has been known. However, with regard to the "comfort feeling", conventionally, there is no definite physical index, and this is due to the feeling of each driver.

A sound that gives this "comfortable feeling" (comfortable sound)
It is known that, in a hydraulic excavator, it is generated especially by a sound in a machine room in which an engine is mounted or a hydraulic pulsating sound is propagated, and becomes large at a specific frequency.

For this reason, conventionally, the problem has been dealt with by insulating the space between the machine room and the cabin, using a sound absorbing material, or skipping a specific engine speed. In reality, there was room to improve the habitability of the cabin in the future.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a driver's cab structure of a construction machine capable of reducing the muffled noise in the driver's cab and improving its habitability. Is.

[0008]

The invention according to claim 1 is
In a construction machine in which a machine room equipped with an engine and an operator's cab of a substantially sealed structure are provided on the main body frame, the sound inside the operator's cab caused by the operation of the engine It is characterized by having a sound release hole for letting it escape.

It is considered that an air column resonance phenomenon occurs in a low frequency range in a small driver's cab, and thereby a standing wave is generated to locally raise the sound pressure, that is, a so-called muffled sound is generated.
This is consistent with the fact that the muffled noise becomes particularly loud at low engine speeds such as idling of the engine. This muffled sound raises the sound pressure in the driver's cab and presses the eardrum of the driver's ear, which gives strong discomfort. In this respect, according to the above configuration, the peripheral wall forming the driver's cab was provided with the sound vent hole for releasing the sound in the driver's cab caused by the operation of the engine. The sound pressure is reduced by being released from the sound vent toward the outside where the pressure level is low. As a result, the driver does not feel the discomfort when the engine speed is low, and the habitability in the driver's cab is improved.

The sound pressure of the muffled noise largely varies depending on the location in the driver's cab, and becomes particularly high when the door is open.
In this case, the sound pressure inside the driver's cab becomes maximum on the side opposite to the door, that is, on the rear portion of the peripheral wall. Therefore, as in the invention according to claim 2, the operator's cab is formed in a box shape having a ceiling, front and rear walls, and left and right side walls as peripheral walls, and a door is provided at the front part of one side wall, and If the hole is provided in the rear portion of the peripheral wall of the operator's cab, the muffled sound at the portion where the sound pressure is high can easily escape.

For example, if the sound vent hole is provided in the rear portion of the peripheral wall of the operator's cab near the diagonal position of the door as in the third aspect of the present invention, the sound pressure is increased in the muffled portion. Sound becomes easier to escape.

By the way, when a sound vent hole is opened in the peripheral wall of the driver's cab, rainwater, dust, earth and sand (hereinafter referred to as rainwater, etc.) may enter the driver's cab and impair its habitability. Therefore, as in the invention described in claims 4 and 5, at least a part of the peripheral wall of the cab has a double wall structure in which an inner wall and an outer wall are opposed to each other with a predetermined gap, and a sound vent hole is provided. By providing the inner wall and the outer wall of the double wall at positions shifted from each other in the up-down direction or the left-right direction (claim 4), or by providing a sound vent hole in the outer wall of the double wall and removing the sound. By providing a baffle plate facing the holes to prevent rainwater and the like from entering through the sound holes (Claim 5), it is not possible to directly see through both holes. Are prevented from entering the driver's cab, and the habitability of the driver's cab is not impaired.

In the double wall structure, the sound vent hole is
Since the inner wall and the outer wall of the double wall are provided at positions shifted from each other in the vertical direction or the left-right direction, most of the muffled sound escaped from the sound hole in the inner wall goes to the outside from the sound hole in the outer wall. Although it is escaped, a part of it may be reflected by the outer wall and return to the cab again through the sound hole in the inner wall. Therefore, as in the sixth aspect of the invention, a sound absorbing material may be provided so as to face the sound vent hole of the inner wall of the double wall to absorb the sound escaping from or entering the sound vent hole. For example, the muffled sound escaped from the sound hole in the inner wall is reduced in sound pressure by the sound absorbing effect of this sound absorbing material, and is reflected directly on the outer wall to return to the cab again through the sound hole in the inner wall. Less likely to come. Further, even when the baffle plate is provided, the same action as described above can be obtained by providing the baffle plate with the sound absorbing material. Further, when the engine speed is high, the sound pressure outside the vehicle increases, but this sound absorbing material can absorb the sound that enters the inside of the driver's cab.

[0014]

1 is a diagram showing the overall construction of a crawler type hydraulic excavator. A vehicle body of an hydraulic excavator as an example of a construction machine comprises a lower traveling body 1 and an upper revolving superstructure 2. The excavation attachment 3 is mounted on the front part of the upper revolving structure 2 so that it can be raised and lowered.

The lower traveling body 1 is composed of left and right crawler frames 4 and crawlers 5 (both of which are shown on one side only).
The both-side crawlers 5 are individually driven by the left and right traveling motors 7 to travel. The upper revolving structure 2 includes a revolving frame (corresponding to a main body frame) 8, a cabin (corresponding to an operating room) 9 having a substantially closed structure, and a machine room 10 having an engine, a hydraulic pump driven by the engine, and the like. Are provided at the front and back.

The cabin 9 is formed in a box shape having a ceiling, front and rear walls, and left and right side walls as a peripheral wall, and is shielded from the outside air to protect the driver from outside noise and dust, and the above-mentioned outline It has a closed structure and is equipped with an air conditioner (not shown) to ensure its habitability.

The excavation attachment 3 includes a boom 17,
A boom cylinder 18 that expands and contracts by the pressure oil from the hydraulic pump to raise and lower the boom, an arm 19, an arm cylinder 20 that rotates the arm 19, a bucket 21, and a bucket cylinder 22 that rotates the bucket. It has and.

FIG. 2 is a horizontal sectional view showing the detailed construction of the cabin of the crawler type hydraulic excavator according to the present embodiment. As shown in FIG. 2, the cabin 9 has four corners between an outer wall and an inner wall. Pillars 91 to 94 having a so-called double-walled structure, which are formed with a predetermined gap interposed, are erected so that the cabin 9
The rigidity required for is secured.

Large windows 95 to 98 are fitted between the pillars 91 to 94 adjacent to each other, and the driver can visually recognize the outside through the windows 95 to 98 over substantially the entire circumference. It is like this.

At the front side of FIG. 2, there is provided a door 30 which can be opened and closed outwardly around the hinge. When the door 30 is not in operation, the door 30 is rotated in the direction of the arrow and opened until the state shown by the alternate long and short dash line is reached. While the driver goes in and out of the cabin 9,
During the work, the door 30 can be rotated in the direction opposite to the arrow direction to be in the fully closed state shown by the solid line. Besides, it goes without saying that the cabin 9 is provided with left and right operation levers 101 to 104 for the driver to operate, a driver's seat 110, and the like.

By the way, in the prior art, when the engine is idling, a sound in the low frequency region is generated in the cabin 9,
It was explained that the habitability of the cabin 9 is adversely affected. Therefore, in order to eliminate such a sound, the present inventors conducted an experiment using a single cabin of an actual machine and an analysis using a numerical model (three-dimensional analysis model) of the same cabin.

That is, first, the acoustic field in the cabin was analyzed by applying the condition of rear wall excitation to the above analytical model.
Figure 3 shows the results. In the figure, the horizontal axis is the sound frequency (Frequency (Hz)), and the vertical axis is the sound pressure at the ears of the virtual driver's right ear at the excitation element volume velocity. The divided value is expressed in decibels (Transfer Function (dB)).

As a result, if the door is fully opened and the rear wall is vibrated, as shown by the solid line in FIG. 3, the low frequency region of about 40 to 50 Hz (indicated by the white arrow in the figure) in the cabin. The sound pressure in Fig. 3) rises to about 70 dB, while the door is fully closed and the rear wall is vibrated, as shown by the broken line in FIG. It turns out that there is no rise.

That is, the increase in sound pressure when the door is fully opened is a so-called muffled sound in which a standing wave is generated in the cabin due to the resonance phenomenon of the air column in the cabin and the sound pressure is locally increased. The increase in sound pressure gives a strong discomfort to the worker by pressing the eardrum of the right ear of the worker during non-work.

Then, the above cabin alone was actually vibrated in a laboratory to analyze the sound field in the cabin. FIG. 4 shows the results, which shows a horizontal cross section of the cabin, in which the lower side is the left side wall, the upper side is the right side wall, the left side is the front wall, and the right side is the rear wall. The door is installed only on the left wall of the. However, in this figure, this door is in a fully opened state, and only the door opening is shown.

In this sound field analysis, when the door was fully opened and the rear wall was vibrated at a frequency of 45 Hz, a sound pressure distribution as shown in FIG. 4 was obtained in the cabin. In the figure, the sound pressure is low where the mesh density is low, and the sound pressure is high where the mesh density is high. In this sound pressure distribution, the sound pressure distribution is on the opposite side of the door opening, that is, near the rear wall. The sound pressure becomes higher and higher, and then reaches the maximum on the wall.

Therefore, in the present embodiment, from the above-mentioned experiment and analysis results, it is considered that the most noise reduction effect can be obtained, and the rear portion of the peripheral wall of the cabin 9 opposite to the door 30 (corresponding to the diagonal position of the door). Predetermined sound release hole 40 on top of pillar 94
Will be provided.

When the sound pressure rises due to the muffled sound in the cabin 9 during engine idling or the like, the muffled sound in the cabin 9 is generated by the sound muffler 40.
By escaping from 0 to the outside (in the atmosphere) where the pressure level is low, the sound pressure is reduced.

More specifically, vertically elongated sound release holes 40a and 40b, which are respectively opened in the inner wall 94a and the outer wall 94b of the double wall of the pillar 94, are provided at positions vertically offset from each other. To prevent the holes from overlapping (see FIG. 5 (a)), or to provide the holes 40a and 40b at positions offset from each other in the lateral direction of the double wall of the pillar 94 so that the holes do not overlap. (See FIG. 5B). Note that the sound holes 40a and 40b
The detailed position, shape, and size of are properly determined so that the sound pressure of the muffled sound in the cabin 9 is reduced based on the above-mentioned experiment and analysis results.

The XX cross section of the pillars 94a and 94b shown in FIG. 5 (b) passing through the respective sound holes 40a and 40b corresponds to that of FIG. In this way, by shifting the sound hole 40b of the outer wall 94b and the sound hole 40a of the inner wall 94a to the left and right by the width thereof, it is possible to prevent rainwater and the like from entering the cabin 9 from the inner wall 94a. . In the case of vertically shifting, in order to prevent rainwater from entering the cabin 9, the sound hole 40 of the inner wall 94a is provided.
It is preferable to set a to a position higher than the sound hole 40b of the outer wall 94b. In addition, the sound hole 40 (40a, 40b)
Is provided on the upper part of the pillar 94 (94a, 94b)
This is to avoid interference between the lower rear portion of the pillar 94 and the machine room 10 adjacent to the pillar 94.

Further, a sound absorbing material 41 for absorbing muffled sound may be provided at a position of the inner wall 94a of the outer wall 94b constituting the double wall of the pillar 94, which is opposed to the sound hole 40a (FIG. 6). reference). The sound absorbing material 41 is made of a porous material such as glass wool and rock wool, and as shown in FIG. 6, the sound hole 40a of the inner wall 94a.
It is preferable to have a larger area.

In that case, the sound release hole 40 of the inner wall 94a
By absorbing a part of the muffled sound escaped from a, the sound absorbing material 41 absorbs a small amount of the muffled sound returning to the sound vent hole 40a of the inner wall 94a due to the reflection in the double wall, thereby reducing the muffled sound. Can be efficiently released to the outside from the sound hole 40b of the outer wall 94b.

Further, the baffle plate 42 is arranged so as to face the sound release hole 40b of the outer wall 94b forming the double wall of the pillar 94.
May be provided (see FIG. 7). This baffle plate 4
2 is bent in a Z-shape in cross section, and one end thereof is sandwiched between the inner wall 94a and the outer wall 94b to be fixed, and the other end is positioned in the gap between the inner wall 94a and the outer wall 94b. The sound holes 40a and 40b on both walls are arranged so that they cannot be seen, and even if rainwater or the like that cannot be prevented only by the difference between the sound holes 40a and 40b is penetrated by the baffle plate 42, Can be reliably prevented. In FIG. 7, the sound absorbing material 41 is provided on the baffle plate 42 so as to face the sound release hole 40a of the inner wall 94a, thereby providing the sound absorbing effect.

The sound absorbing material 41 also plays a role of preventing middle and high frequencies outside the cab generated during work from entering the cabin 9 through the sound vent 40 (see FIG. 8).

As described above, according to the present embodiment, the pillar 94 forming the cabin 9 is provided with the sound vent hole 40 for releasing the muffled sound in the cabin 9 caused by the operation of the engine. The muffled sound generated inside 9 is released to the outside through the sound release hole 40, and in the sound pressure distribution inside the cabin 9, the sound pressure at the rear portion of the peripheral wall where the sound pressure is high in the past is effective. It has been reduced. As a result, the driver's discomfort is lessened, and the habitability in the cabin 9 is improved.

In the above embodiment, the box-shaped cabin 9 having the peripheral wall consisting of the ceiling surface and the four front, rear, left and right sides has been described, but other shapes, for example, a polygonal column having five or more peripheral walls or a continuous shape. It may be a cabin or the like formed in a cylindrical shape having a peripheral wall. Further, the door 30 does not necessarily have to be attached to the left side wall, but may be attached to the right side wall. Further, the door 30 may be slid to open and close instead of opening and closing outward around the hinge.

Further, in the above-described embodiment, the sound vent hole 40 is provided only in the pillar 94 forming a part of the peripheral wall of the cabin 9, but the sound vent hole may be provided in other peripheral walls. Further, the sound vent hole 40 is not limited to one place, and may be provided in two or more places. The shape of the sound vent hole 40 is not limited to a vertically long hole, and may be a horizontally long hole, a square hole, a round hole, a slit, or the like, and may also have a louver.

Although the cabin of the small hydraulic excavator has been described in the above embodiment, it is needless to say that the present invention can be applied to the cab structure of large hydraulic excavators, cranes and other construction machines. However, the present invention is
It is particularly suitable for a small hydraulic excavator having a narrow cabin and having a hydraulic system that easily generates noise due to pulsation of pressure oil.

[0039]

According to the first aspect of the present invention, when the sound pressure in the driver's cab rises, the sound in the driver's cab escapes from the sound vent toward the outside where the pressure level is low, thereby reducing the sound pressure. To be done. As a result, it is possible to improve the habitability in the driver's cab without giving a strong discomfort to the driver when the engine rotates at a low speed.

According to the second and third aspects of the present invention, it is possible to easily release the muffled sound of the portion where the sound pressure is high.

According to the fourth and fifth aspects of the present invention, the sound vent holes provided in the inner wall and the outer wall of the double wall are not directly seen through. Therefore, rainwater or the like can pass through the sound vent holes to the cab. It is possible to prevent intrusion and eliminate the possibility of impairing the habitability of the driver's cab.

According to the invention of claim 6, the sound pressure of the muffled sound escaping from the sound hole of the inner wall is reduced by the sound absorbing effect of the sound absorbing material, and the muffled sound is reflected directly on the outer wall. It is possible to reduce the risk of returning to the cab again through the sound vent hole in the inner wall. Even when the baffle plate is provided, the same effect as described above can be obtained by providing the baffle plate with the sound absorbing material. Also, when the engine speed is high, the sound pressure outside the vehicle increases, but since this sound absorbing material can absorb the sound that enters the inside of the driver's cab, it can High frequency waves can be prevented from passing through the sound vent holes and entering the driver's cab.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a crawler hydraulic excavator.

FIG. 2 is a horizontal sectional view showing a schematic structure of a cabin of the crawler hydraulic excavator according to the present embodiment.

FIG. 3 is a diagram showing a sound field analysis result when the door is fully opened and when the door is fully closed by an analysis model.

FIG. 4 is a diagram showing a sound field analysis result when a door is fully opened by an actual machine model.

FIG. 5 is a front view of the sound vent hole seen from the inner wall side,
(A) shows the case where the staggered holes are provided in the vertical direction, and (b) shows the case where the staggered holes are provided in the lateral direction.

FIG. 6 is a transverse cross-sectional view of a sound hole, showing a case where a sound absorbing material is provided.

FIG. 7 is a cross-sectional view of the sound vent hole, showing a case where a sound absorbing material and a baffle plate are provided.

8 is a cross-sectional view of the sound vent hole, showing a case where a sound absorbing material is further provided in FIG. 7. FIG.

[Explanation of symbols]

8 Swivel frame (corresponding to the main frame of construction machinery) 9 cabins (corresponding to the cab) 91-94 pillars (corresponding to a part of the peripheral wall) 94a inner wall 94b outer wall 95-98 window glass 10 Machine room 30 doors 40 sound hole 40a Sound hole on the inner wall 40b Sound hole on the outer wall 41 sound absorbing material 42 baffle

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Claims (6)

[Claims] 1. A construction machine in which a machine room equipped with an engine and a driver's cab having a substantially sealed structure are provided on a main body frame, and a peripheral wall forming the driver's cab has a driver's cab caused by the operation of the engine. A cab structure for construction machinery, which is provided with a sound vent hole that allows the sound of the above to escape to the outside. 2. The cab is formed in a box shape having a ceiling, front and rear walls, and left and right side walls as peripheral walls, and has a door at the front part of one side wall, and the sound vent hole is provided in the cab. The cab structure of the construction machine according to claim 1, wherein the cab structure is provided at a rear portion of the peripheral wall. 3. The cab structure of a construction machine according to claim 2, wherein the sound vent hole is provided in a rear portion of the peripheral wall of the cab near the diagonal position of the door. 4. At least a part of the peripheral wall of the cab forms a double wall structure in which an inner wall and an outer wall are opposed to each other with a predetermined gap, and the sound vent hole is an inner wall of the double wall. The cab structure of the construction machine according to any one of claims 1 to 3, wherein the cab structure and the outer wall are provided at positions vertically and laterally offset from each other. 5. A double wall structure in which an inner wall and an outer wall are opposed to each other with a predetermined gap, at least a part of a peripheral wall of the cab, and a sound vent hole is formed in the outer wall of the double wall. The construction machine according to any one of claims 1 to 3, further comprising a baffle plate provided opposite to the sound vent hole to prevent rainwater and the like from entering through the sound vent hole. Cab structure. 6. The double wall inner wall facing the sound vent hole,
6. The cab structure of a construction machine according to claim 4, further comprising a sound absorbing material for absorbing a sound escaping from the sound vent hole or a sound entering the sound vent hole.