Noise reduction structure for cab of working vehicle

Details Noise reduction structure for cab of working vehicle Noise reduction structure for cab of working vehicle

2000-06-13

2003-04-22

Hsieh, Shih-Yung (Department: 2837)

Acoustics

Sound-modifying means

Housing or enclosure

C181S202000, C181S204000, C181S207000, C181S208000

Reexamination Certificate

active

06550571

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a noise reduction structure for a cab of a working vehicle such as a hydraulic shovel.
BACKGROUND ART
A hydraulic shovel
1
being a working vehicle shown in FlG.
9
has a base carrier
2
and a revolving superstructure
4
rotatably mounted on the base carrier
2
(for example, Japanese Patent Laid-open No. 8-81976). The revolving superstructure
4
has a frame
12
at the lower part thereof. A working machine
6
is provided in the almost center of the front portion of the frame
12
, a cab
10
is provided on either left or right side of the front portion thereof, and an engine room
8
, which is covered with a cover and houses power plants such as an engine and a hydraulic pump not illustrated therein, is provided at the rear portion thereof.
In
FIG. 10
, a cab
10
c
is mounted on a top face of a frame
12
c
via vibration isolating members (not illustrated), with predetermined distance being spaced from the top face of the frame
12
c
and the front face of the engine room
8
. The frame
12
c
is formed to be a frame shape so as to cover the entire perimeter of the side face of the lower part of the cab
10
c.
A cover
14
for protecting the bottom face of the cab
10
c
from earth and stones, and muddy water is mounted on the bottom face of the frame
12
c.
Further, a lever stand
26
mounted with a working machine lever
30
for operating the working machine
6
, a console
28
mounted with a control unit
50
, and a traveling lever
40
for performing a traveling operation, are mounted on the floor
11
c
of the cab
10
c.
Pilot valves
31
and
41
for converting pilot oil pressure from a pilot pump (not illustrated) into command pilot oil pressure corresponding to a lever manipulated variable are respectively provided at the lower portion of the working machine lever
30
and the traveling lever
40
. A plurality of hydraulic hoses
32
and
42
, which are connected to hydraulic devices such as a pilot pump, an operating valve and a tank not illustrated, are connected to the pilot valves
31
and
41
. It should be noted that control cables
32
and
42
are used instead of the hydraulic hoses
32
and
42
in some examples. A wiring harness
52
for exchanging signals with control devices, detectors and the like not illustrated is connected to the control unit
50
.
The traveling lever
40
is mounted on the top face of the floor
11
c,
and thus the pilot valve
41
of the traveling lever
40
is mounted so as to be protruded below the floor
11
c
from a through-hole
45
of the floor
11
c.
The hydraulic hose
42
connected to the pilot valve
41
at a portion below the floor
11
c
extends under the floor
11
c
to be connected to the hydraulic devices behind the cab
10
c.
The working machine lever
30
is mounted on the lever stand
26
. Since the pilot valve
31
of the working machine lever
30
is located above the floor
11
c,
the hydraulic hose
32
connected thereto extneds under the floor
11
c
via a gromet
37
attached to a through-hole
35
of the floor
11
c
from above the floor
11
c
to be connected to the hydraulic devices behind the cab
10
c.
As shown in FIG.
11
A and
FIG. 11B
, the gromet
37
is in an almost oval shape having a thin center portion
37
a
in the center portion and a thick perimeter portion
37
b
in the perimeter portion, and is made by rubber molding. A plurality of holes
37
c
having almost the same diameter as an outer diameter of the hydraulic hose
32
are provide at predetermined intervals in the center portion
37
c,
and slits
37
d
connecting the adjacent two holes
37
c
and
37
c
with each other arc provided for the purpose of passing a mouth piece of the hydraulic hose
32
through. A groove
37
e
with a predetermined depth with almost the same width as the thickness of the floor
11
c
is provided on an outer perimeter surface of the perimeter portion
37
b.
Further, the working machine lever
30
has a structure which is capable of sliding in a longitudinal direction of the vehicle in accordance with a physique and preference of an operator, and in accordance with an operational situation such as an operation of digging a deep hole in which a forward tilting posture is required. The wiring harness
52
from the control unit
50
extends under the floor
11
c
via the through-hole not illustrated of the floor
11
c
from above the floor
11
c
to be connected to the control devices and detectors outside the cab
10
c.
When an operator starts the engine and manipulates the working machine lever
30
or the traveling lever
40
to operate the hydraulic shovel
1
for operation, noises are generated from the power plants such as the engine, the hydraulic pump, and the like. The noises generated propagate into the cab
10
c,
and they propagate in such a manner as to especially concentrate on a rear face of the cab
10
c,
which is near the noise sources. Conventionally, in order to reduce noise, a structure which increases sound-insulating effectiveness, for example, by reducing a gap by means of a gromet, or providing sound-insulating members and the like is adopted in the cab
10
c.
However, recently, a demand for increased riding comfort and sound-insulating effectiveness in the cab
10
c
grows. Accordingly, further noise reduction inside the cab
10
c
is required.
Further, by sliding movement of the working machine lever
30
, the hydraulic hose
32
moves together with the pilot valve
31
. In this situation, due to the sliding amount, the rigidity and the thickness of the hydraulic hose
32
, as shown in
FIG. 11C
, the hose
32
is on the skew at the gromet
37
section, which together with the existence of the slit
37
d,
causes a gap due to twisting. Further, since the hydraulic hose
32
is not fixed in the vicinity of the gromet
37
in order to absorb play caused by the sliding movement, a gap caused by the twist sometimes remains even if the sliding movement is stopped to return to the original position. For this reason, in the through-hole
35
, a degree of sound-insulating effectiveness of the gromet
37
is extremely reduced. In addition, in the through-hole
45
section to which the traveling lever
40
is mounted, a secure sound-insulating structure sometimes cannot be achieved for the reason of design.
Since the cab
10
c
is mounted to be spaced from the frame
12
c,
due to the noise entering from a gap between the cab
10
c
and the frame
12
c,
a level of noise below the floor
11
c
is higher. Consequently, the noise below the floor
11
c
enters the inside of the cab
10
c
through the through-holes
35
and
45
where sound insulation is incomplete, which poses the big barrier to the noise reduction inside the cab
10
c.
SUMMARY OF THE INVENTION
The present invention is made in view of the above disadvantages, and its object is to provide a noise reduction structure for a cab of a working vehicle, by which a higher level of noise reduction effectiveness can be surely obtained, in a working vehicle such as a hydraulic shovel. Another object is to provide the noise reduction structure for the cab which prevents noise from entering from through-holes provided in a floor and a wall surface of the cab for providing hydraulic hoses and a wiring harness, and has a higher level of noise reduction effectiveness, in the working vehicle such as a hydraulic shovel.
In order to attain the above object, a first aspect of a noise reduction structure for a cab of a working vehicle according to the present invention is in a noise reduction structure for a cab of a working vehicle, characterized in that
a sound-insulating chamber adjacent to a cab is provided at a position of at least one of the following: under a floor of the cab, behind a rear wall of the cab, and at a side of a side wall of the cab.
According to the above configuration, out of the paths through which noises propagate into the cab of the working vehicle such as a hydraulic shovel, the noises propagating into the cab from the rear wall of the cab, the floor of the c

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