Acoustics – Sound-modifying means – Housing or enclosure
Reexamination Certificate
2000-10-06
2002-06-18
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Housing or enclosure
C181S225000, C180S069200, C123S19800E
Reexamination Certificate
active
06405825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a noise absorption mounting structure for a working vehicle such as a hydraulic excavator and, more particularly, to a structure for mounting the noise absorption blades which can be tuned optimum against noises.
2. Related Art
In order to introduce the air for cooling the radiator or oil cooler of a working vehicle, an air hole is formed in the cover of an engine room or the like. Noise absorption blades may be mounted in the air hole so as to make lower the noises. This noise absorption blade mounting structure of the prior art is disclosed in Unexamined Published Japanese Patent Application No. H9-123771, for example, of which
FIG. 20
is a section of an air hole portion.
In
FIG. 20
, a cooling wind intake duct
56
is disposed in the space between an opening
52
in the upper portion of an engine room
51
and the front face portions of a radiator
53
and an oil cooler
54
. The cooling wind intake duct
56
is composed of a plurality of wind guide plates
57
a
to
57
f
, by which a cooling wind
58
taken from the opening
52
is divided and is homogeneously introduced to the radiator
53
and the oil cooler
54
. On the other hand, the wind guide plates
57
a
to
57
f
are covered on their faces exposed to the wind with noise absorption members
59
a
to
59
j
, and the exit end portions of the individual wind guide plates
57
a
to
57
f
are sufficiently spaced from the front face portions of the radiator
53
and the oil cooler
54
. Thus, the noises emanating out of the engine room
51
are lowered, and the flow velocity fluctuation of the cooling wind
58
in the cooling wind intake duct
56
is suppressed to reduce the noises of a cooling fan
55
.
Another technique of the prior art is disclosed in Unexamined Published Japanese Utility Model Application No. H5-50027, for example.
FIGS. 21 and 22
are a front elevation and a sectional view of an air hole portion, as disclosed.
FIG. 22
is a sectional view taken along line F—F of FIG.
21
.
In
FIGS. 21 and 22
, noise absorption blades
61
are so mounted in the inner side portion
63
of a front mask
62
as to confront the whole area or a radiator core
64
. When the front mask
62
is demounted for cleaning the radiator core
64
, the noise absorption blades
61
can be demounted together with the front mask
62
. Moreover, this front mask
62
mounting the noise absorption blades
61
are so hinged to a radiator guard
66
through a hinge mechanism
65
as can be opened and closed, and are fixed on the radiator guard
66
by means of bolts
67
. This construction makes it easy to assemble the noise absorption blades
61
and to clean the radiator core
64
.
However, the prior arts thus far described have the following problems.
In the former technique disclosed in Unexamined Published Japanese Patent Application No. H9-123771, the wind guide plates
57
a
to
57
f
are fixed in the engine room
51
. This raises problems that no tuning can be made against the noises and that the noise absorption members
59
a
to
59
j
cannot be replaced even when they are deteriorated. On the other hand, the wind guide plates
57
a
to
57
f
and the noise absorption members
59
a
to
59
j
have different shapes and are high at their manufacture costs.
In the latter technique disclosed in Unexamined Published Japanese Utility Model Application No. 5-50027, on the other hand, There is caused by the structure of the noise absorption blades
61
a problem that the tuning is made difficult against the noises. Therefore, it takes a long time to design the noise reduction. Although a number of ventilation holes
62
a
are formed in the front mask
62
, however, they have such a high ventilation resistance as to raise problems that the wind noises are high and that an air flow cannot be increased.
SUMMARY OF THE INVENTION
Noting the above-specified problems of the prior art, the invention has an object to provide a noise absorption blade mounting structure for a working vehicle, which is enabled to be excellent in the draft straightening property in an air hole of the cover of an engine room and excellent in the strength and appearance of the cover, by making noise absorption blades having a high noise absorption effect of a simple structure to mount/demount the noise absorption blades simply in/from the air hole thereby to facilitate the tuning against the noises coming from the engine room and the maintenances of the noise absorption blades.
In order to achieve the aforementioned object, according to a first aspect of the invention, there is provided a noise absorption blade mounting structure for a working vehicle, comprising: a cover covering a noise source including an engine, a cooling fan and a hydraulic unit and having an air hole for ventilating the ambient air therethrough, the cover being capable of being opened and closed; and a plurality of noise absorption blades disposed in the vicinity of the air hole for absorbing the noises which might otherwise leak from the inside to the outside of the cover. Each of the noise absorption blades includes: a core member; noise absorption members mounted on the two faces of the core member; and mounting members formed on the end faces of the noise absorption members. The cover includes in its air hole straightening members for straightening the draft in front of, as taken in the ventilation direction, the noise absorption blades.
According to the first aspect of the invention, the noise absorption members are mounted on the two faces of the core member so that the noise absorption is effected on the two faces of the ventilation passage. Therefore, the noise absorption area is doubled even with the noise absorption member having the same thickness as that of the prior art so that the noise absorption effect is improved. Since the core member is sandwiched between the noise absorption members, moreover, there is effected a damping act on to attenuate the sound waves, when reflected on the core member, by their energy loss. On the other hand, the sound waves, as emanating from the opposite side of the core member, are also attenuated by the noise absorption action of the noise absorption member on the opposite side of the core member so that the noise absorption effect is further improved.
As a result, even with the simple construction and the same size as that of the prior art, the noise absorption blades can be given a high noise absorption reducing effect at the air hole of the vehicle.
On the other hand, the mounting members are formed at the end faces of the noise absorption member so that the noise absorption blades can be firmly mounted on the vehicle body by the simple construction having a small number of parts.
As a result, the noise absorption blades are given a structure capable of enduring the severe vibrations or impacts on the vehicle.
Since the noise absorption blades have the simple construction, moreover, their individual components are set as the standard parts. By cutting and bending works simply, therefore, the noise absorption blades of special sizes can be easily manufactured in relation to the noise sources or the peripheral devices so that they can be easily tuned at low costs.
On the other hand, he straightening members for straightening the draft are disposed in front of the noise absorption blades and in the air hole of the cover so that the draft flows smoothly with little ventilation resistance but without any vortex or separation. As a result, there can be retained, a sufficient cooling wind. On the other hand, the dust or moisture is prevented from coming from the end faces of the noise absorption members at the end portions, as taken in the ventilation direction, of the noise absorption blades so that the noise absorption effect can be prevented from aging.
Moreover, the straightening member also acts as a strengthening member to retain the strength of the air hole of the cover, and the noise absorption blades and their mounting portions are located at the back
Kawakami Takashi
Yabe Mitsuo
Dang Khanh
Komatsu Ltd.
Varndell & Varndell PLLC
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