Noise reduction structure for a cab of a working vehicle

Abstract: A noise reduction structure for a cab of a working vehicle, by which a high degree of noise reduction effectiveness can be surely obtained, is provided. For this purpose, the noise reduction structure has a configuration in which a sound-insulating chamber (A; B; C) adjacent to a cab (10a) is provided at a position of at least one of the following: under a floor (11a) of the cab (10a), behind a rear wall of the cab (10a), and at a side of a side wall of the cab (10a).

Description: 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 FIG. 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 10c is mounted on a top face of a frame 12c via vibration isolating members (not illustrated), with predetermined distance being spaced from the top face of the frame 12c and the front face of the engine room 8. The frame 12c 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 10c. A cover 14 for protecting the bottom face of the cab 10c from earth and stones, and muddy water is mounted on the bottom face of the frame 12c. 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 11c of the cab 10c. 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 11c, and thus the pilot valve 41 of the traveling lever 40 is mounted so as to be protruded below the floor 11c from a through-hole 45 of the floor 11c. The hydraulic hose 42 connected to the pilot valve 41 at a portion below the floor 11c extends under the floor 11c to be connected to the hydraulic devices behind the cab 10c. 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 11c, the hydraulic hose 32 connected thereto extneds under the floor 11c via a gromet 37 attached to a through-hole 35 of the floor 11c from above the floor 11c to be connected to the hydraulic devices behind the cab 10c. As shown in FIG. 11A and FIG. 11B, the gromet 37 is in an almost oval shape having a thin center portion 37a in the center portion and a thick perimeter portion 37b in the perimeter portion, and is made by rubber molding. A plurality of holes 37c having almost the same diameter as an outer diameter of the hydraulic hose 32 are provide at predetermined intervals in the center portion 37c, and slits 37d connecting the adjacent two holes 37c and 37c with each other are provided for the purpose of passing a mouth piece of the hydraulic hose 32 through. A groove 37e with a predetermined depth with almost the same width as the thickness of the floor 11c is provided on an outer perimeter surface of the perimeter portion 37b. 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 11c via the through-hole not illustrated of the floor 11c from above the floor 11c to be connected to the control devices and detectors outside the cab 10c. 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 10c, and they propagate in such a manner as to especially concentrate on a rear face of the cab 10c, 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 10c. However, recently, a demand for increased riding comfort and sound-insulating effectiveness in the cab 10c grows. Accordingly, further noise reduction inside the cab 10c 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 37d, 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 10c is mounted to be spaced from the frame 12c, due to the noise entering from a gap between the cab 10c and the frame 12c, a level of noise below the floor 11c is higher. Consequently, the noise below the floor 11c enters the inside of the cab 10c through the through-holes 35 and 45 where sound insulation is incomplete, which poses the big barrier to the noise reduction inside the cab 10c. DE 297 17 226 U1 discloses a centre pivot working vehicle, wherein the hind carriage comprises a drivers cabin and an encapsulated drive assembly spaced apart from a rear wall of the drivers cabin. The encapsulation of the drive assembly is composed of an engine hood, a rear plate, a base plate and two side walls connected by a cross arm. The encapsulation comprises recesses for at least the admission of cool air to a radiator, for discharging heated air from the internal combustion engine and for a hose assembly for delivering hydraulic fluid to hydraulic driving motors. US 4 099 590 discloses an inside engine cover for a cab of a lift truck, wherein the engine cover uses a double wall construction to reduce the engine noise inside the cab. The engine cover comprises a moulded outer shell and a moulded inner liner of a rigid plastic material such as a composite of fibreglass-reinforced polyester resin. For the maintenance of the internal combustion engine of the lift truck, the engine cover is equipped with recesses allowing a direct access to the engine room from the inside of the cab. US 3 918 541 discloses a hollow control console for a cab of a tractor, wherein the control console extends from an outside of the cab near the motor into the inside of the cab. The control console constitutes a sound-insulating chamber in which a plurality of sound-insulating blocks of different materials are installed for attenuating the noise inside the cab, generated by the internal combustion engine. The control console comprises recesses at least for the steering column and a lever of the tractor. Summary of the invention The present invention is made in view of the above disadvantages, and its object is to provide a working vehicle having a noise reduction structure for a cab, 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 prevent 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. The present invention includes the features as claimed in claim 1. 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 cab, and the side wall of the cab, which are near the noise sources and the main causes of noise, can be reduced by being passed through the sound-insulating chambers. Hence, working environment for an operator can be improved, and working efficiency can be improved. In addition, the sound-insulating chambers can be respectively realized with a simple structure utilizing the existing members such as the floor and the frame; the rear wall of the cab and the engine room; and the side wall of the cab and the boom supporting member. According to an embodiment of the invention, in the working vehicle such as a hydraulic shovel, the hydraulic hoses, the wire harness and the like are provided to extend from the inside of the cab to the outside thereof via the through-holes and the sound-insulating chambers. In this situation, even when sound insulation is difficult at the through-hole section, and even when sound insulation is difficult at the through-hole section at which the manipulating member is directly mounted on the floor, sound insulation is achieved at the exit portion to the outside from the sound-insulating chamber. As a result, noise from the outside is reduced in the sound-insulating chambers, and thereby the noise entering the inside of the cab from the sound-insulating chambers through the through-holes is reduced. Thus, the noise reduction inside the cab is made possible, the working environment for an operator can be improved, and working efficiency can be improved. Further, with the through-hole being provided in the floor of the cab, the sound-insulating chamber may be configured to have the floor of the cab, the frame on which surface the cab is mounted, and the sound-insulating member for padding a gap between the cab and the frame. The sound-insulating chamber has a simple configuration in which the members such as the floor and the frame conventionally used are partially modified as necessary and the sound-insulating member is added. As a result, the noise reduction inside the cab is made possible with a simple structure, and the working environment for an operator is improved, thus making it possible to improve working efficiency. Brief Description of the Drawings FIG. 1 is a sectional side view showing a cab, a frame, and an engine room of a first embodiment of the present invention; FIG. 2 is a perspective view of portions of the frame and engine room, to which the cab is mounted, according to the first embodiment of the present invention; FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1; FIG. 4 is a perspective view showing another embodiment regarding a sound-insulating chamber of the first embodiment of the present invention; FIG. 5 is a view seen in the direction of the arrow 5 in FIG. 4; FIG. 6 is a sectional side view showing a cab and a frame of a second embodiment of the present invention; FIG. 7 is a fragmentary perspective view of a portion of the frame, to which the cab is mounted, according to the second embodiment of the present invention; FIG. 8A and FIG. 8B show another embodiment regarding placement of a sound-insulating member of the present invention, FIG. 8A is an explanatory view in the case in which a circular rubber tube having a plan portion is used, and FIG. 8B is an explanatory view in the case in which a circular rubber tube having a slit is used; FIG. 9 is a side view of a hydraulic shovel being an ordinary working vehicle; FIG. 10 is a sectional side view showing a conventional cab and frame; and FIG. 11A to FIG. 11C are views explaining a state of a gromet and a hose according to a prior art, FIG. 11A is a plan view of the gromet, FIG. 11B is a sectional side view of the gromet with hydraulic hoses being attached therein, and FIG. 11C is a sectional side view of the gromet with the hydraulic hoses being on the skew. Best Mode for Carrying out the Invention A preferred embodiment of the present invention will be explained below with reference to the drawings. Here, as a working vehicle to which a noise reduction structure for a cab of a working vehicle according to the present invention, an example of a hydraulic shovel 1 shown in FIG. 9 is cited for explanation, but the present invention is not limited to the above. A first embodiment of the present invention will be explained in detail with reference to FIG. 1, FIG. 2 and FIG. 3. In FIG. 1, a cab 10a is mounted on a top face of a frame 12a via vibration isolating members 18 (See FIG. 2) in each of four corners of a floor 11a of the cab 10a, with predetermined distances being spaced respectively from the top face of the frame 12a and the front face of an engine room 8. The frame 12a is formed to be a frame shape so as to cover the entire perimeter of the side surface of the lower part of the cab 10a. A cover 14 for protecting the bottom face of the cab 10a from earth and stones, and muddy water is mounted on the bottom face of the frame 12a. As shown in FIG. 2, a sound-insulating member 16 consisting of, for example, urethane foam having a predetermined width with a thickness a little larger than a space between the floor 11a and the frame 12a is attached on the top face of the frame 12a along the entire perimeter of the bottom face of the floor 11a. As shown in FIG. 2, a sound-insulating member 17 consisting of, for example, urethane foam having a predetermined width with a thickness a little larger than a space between a rear wall of the cab 10a and the engine room 8 is attached on the front face of the engine room 8 along the entire perimeter of the rear wall of the cab 10a. As shown in FIG. 3, a boom supporting member 13a is vertically provided on a top surface of a frame 21a integrally constructed with the frame 12a, at the side of the side wall of the cab 10a, which is near the center of the vehicle body. A plate 43a, which covers the side wall of the cab 10a integrally with the boom supporting member 13a up to a position at which it meets the rear end surface of the cab 10a, is attached to the boom supporting member 13a by welding or the like on the side toward the rear of the vehicle. The plate 43a has almost the same height as the uppermost end portion of the boom supporting member 13a, and its side surface toward the cab 10a forms the same surface as the side surface of the boom supporting member 13a, which is toward the cab 10a. On the surfaces of the boom supporting member 13a and the plate 43a toward the cab 10a side, a plate 33a having a little shorter length than a space between the side wall of the cab 10a and the boom supporting member 13a is vertically provided along an entire perimeter a little inward from the outer perimeter of a portion facing the side wall of the cab 10a. Further, a sound-insulating member 34a formed of, for example, urethane foam, which has a predetermined width and a little larger thickness than a space between the side wall of the cab 10a and the plate 33a is attached along the entire perimeter of an end portion of the plate 33a toward the cab 10a side. According to the above configuration, a sound-insulating chamber A, which is surrounded by the floor 11a, the sound-insulating member 16, the frame 12a, and the cover 14, is formed under the cab 10a. Noise entering the sound-insulating chamber A is reduced by the insulating action of the members forming the sound-insulating chamber A. Further, a sound-insulating chamber B, which is surrounded by the rear wall of the cab 10a, the sound-insulating member 17, and the engine room 8, is formed behind the rear wall of the cab 10a. Noise entering the sound-insulating chamber B is reduced by the insulating action of the members forming the sound-insulating chamber B. Furthermore, a sound-insulating chamber C, which is surrounded by the side wall of the cab 10a, the boom supporting member 13a, the plate 43a, the sound-insulating member 34a, and the plate 33a, is formed at the side of the side wall of the cab 10a. Noise entering the sound-insulating chamber C is reduced by the insulating action of the members forming the sound-insulating chamber C. According to the above configuration, noises propagating into the cab 10a from the rear wall of the cab 10a, the floor 11a of the cab 10a and the side wall of the cab 10a, which are the paths located near the noise source and mainly causing noises, out of the paths of noises propagating into the cab 10a, can be reduced by being respectively passed through the sound-insulating chambers A, B and C. Thus, working environment for an operator is improved, thereby making it possible to improve working efficiency. Further, the sound-insulating chambers A, B and C can be achieved with a simple structure utilizing the already-existing members such as the floor 11a and the frame 12a, the rear wall of the cab 10a and the engine room 8, and the side wall of the cab 10a and the boom supporting member 13a, respectively. Next, another example of the first embodiment regarding the sound-insulating chamber C will be explained with reference to FIG. 4 and FIG. 5. A boom supporting member 13d is vertically provided on a top face of a frame 21d integrally constructed with the frame 12d, at the side of the side wall of the cab 10d near the center of the vehicle body. A plate 43d, which covers the side wall of the cab 10d integrally with the boom supporting member 13d up to a position at which it meets the rear end surface of the cab 10d, is attached to the boom supporting member 13d by welding or the like on the side toward the rear of the vehicle. The plate 43d has almost the same height as the uppermost end portion of the boom supporting member 13d, and its side surface toward the cab 10d forms the same surface as the side surface of the boom supporting member 13d at the cab 10d side. The frame 12d has beams 22 and 23 which is on the top surface of the frame 21d and extends in a direction of the cab 10d from the side surface of the boom supporting member 13d. Sections of the beams 22 and 23, which face to longitudinal directions of the beams 22 and 23, are in a U-shaped form with the opening thereof facing downward. The beam 22 is located at a rear portion of the cab 10d, and the beam 23 is located almost in the center of the cab 10d. On the surfaces of the boom supporting member 13d and the plate 43d toward the cab 10d side, a plate 33d having a little shorter length than a space between the side wall of the cab 10d and the boom supporting member 13d is vertically provided along a side a little inward from the upper end and the left and right end of the perimeter of a portion facing to the side wall of the cab 10d. One of the longitudinal ends of the plate 33d is in contact with the beam 22 and the other end is in contact with the beam 23. Further, a sound-insulating member 34d formed of, for example, urethane foam, which has a predetermined width and a little larger thickness than a space between the side wall of the cab 10d and the plate 33d is attached to an end portion of the plate 33d toward the cab 10b side along the entire surface of the end portion. On the top face of the plate 21d, a plate 44, which has almost the same height as a space between the plate 21d and the cab 10d, and which has a width almost equal to a space between the beams 22 and 23, is attached at a lower position of the side wall of the cab 10d near the center of the vehicle. According to the above configuration, a sound-insulating chamber C1, which is surrounded by the side wall of the cab 10d, the boom supporting member 13d, the plate 43d, the sound-insulating member 34d, the plate 33d, the plate 21d, the beams 22 and 23, and the plate 44, is formed at the side of the side wall of the cab 10d. A noise entering the sound-insulating chamber C 1 is reduced by the insulating action of the members forming the sound-insulating chamber C1. Even if a sound-insulating member of urethane foam or the like is used instead of the plate 44, the same operational effects can be obtained. Further, even if the plate 44 is eliminated, and a configuration in which the sound-insulating chamber C1 is communicated with the sound-insulating chamber A under the cab 10d, the same operational effects can be obtained. Next, a second embodiment according to the present invention will be explained in detail with reference to FIG. 6 and FIG. 7. In FIG. 6, a cab 10b is mounted on a top face of a frame 12b via vibration isolating members 18 shown in FIG. 7 in each of four corners of a floor 11b, with predetermined distance being spaced from the top face of the frame 12b. The frame 12b 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 10b. A cover 14 for protecting the bottom surface of the cab 10b from earth and stones, and muddy water is mounted on the bottom surface of the frame 12b. 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 traveling operation, are mounted on the floor 11b of the cab 10b. Pilot valves 32 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. Further, 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 surface of the floor 11b. The pilot valve 41 of the traveling lever 40 is mounted so as to be protruded below the floor 11b from a through-hole 45 of the floor 11b, and the hydraulic hose 42 connected thereto extends under the floor 11b to be connected to the hydraulic devices behind the cab 10b. In the through-hole 45 section to which the traveling lever 40 is mounted, a proper sound insulating structure can not be sometimes achieved due to the design. 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 11b, the hydraulic hose 32 connected thereto extends under the floor 11 via a gromet 37 attached at a through-hole 35 of the floor 11b from above the floor 11b to be connected to the hydraulic devices behind the cab 10b. As shown in FIG. 11A and FIG. 11B, the gromet 37 is in an almost oval shape having a thin center portion 37a in the center portion and a thick perimeter portion 37b in the perimeter portion, and is made by rubber molding. A plurality of holes 37c having almost the same diameter as an outer diameter of the hydraulic hose 32 are provide at predetermined intervals in the center portion 37a, and slits 37d connecting the adjacent two holes with each other are provided for the purpose of passing a mouth piece of the hydraulic hose 32 through. A groove 37e with a predetermined depth with almost the same width as the thickness of the floor 11c is provided on an outer perimeter surface of the perimeter portion 37b. Further, the working machine lever 30 has 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. By the sliding movement, the hydraulic hose 32 is also moved together with the pilot valve 31. As a result, in accordance with a sliding amount, and rigidity and thickness of the hydraulic hose 32, the hose 32 is on the skew at the gromet 37 section, thus causing a gap due to the twist as shown in FIG. 11C. The wiring harness 52 from the control unit 50 extends under the floor 11b via the through-hole 35 from above the floor 11b to be connected to the control devices and detectors outside the cab 10b. In some cases, control cables 32 and 42 are used instead of the hydraulic hoses 32 and 42. In these cases, the traveling lever 40 or the working machine lever 30 is connected to the hydraulic devices behind the cab 10b by means of the control cables 32 or 42, and a gap is similarly produced at the grommet 37 section. As FIG. 7 shows, on the top surface of the frame 12b, the sound-insulating member 16 made of urethane foam, which has a predetermined width and a little larger thickness than the space between the floor 11b and the frame 12b, is attached along the entire perimeter of the bottom surface of the floor 11b. The hydraulic hoses 32 and 42 (or the control cables 32 and 42), and the wiring harness 52 extending under the floor 11b toward the back of the cab 10b are fixed by means of a clamp 24 laterally placed in a line at a position in the vicinity of the rear end portion of the cab 10b on the upper surface of the frame 12b as shown in FIG. 7. According to the above configuration, the sound-insulating chamber A surrounded by the floor 11b, the sound-insulating member 16, the frame 12b and the cover 14 is formed under the cab 10b. Noise entering the sound-insulating chamber A is reduced by the sound insulating action of the members forming the sound-insulating chamber A. As for the form of the hydraulic hoses 32 and 42 (or the control cables 32 and 42) and the wiring harness 52 at the sound-insulating member 16 section, they are laterally aligned in a line and fixed with the clamp 24, and are pressed down by the sound-insulating member 16. Thus, in the sound-insulating member 16 section, noise entering the sound-insulating chamber A from the outside is reduced. As a result, the sound-insulating chamber A becomes a space which less noise enters from the outside. Consequently, even when a sound insulation is difficult at the through-hole 35 section due to a gap caused by the twist occurring at the gromet 37 section, and even when sound insulation is difficult at the through-hole 45 section at which the traveling lever 40 is mounted, noise entering the inside of the cab 10b through the through-holes 35 and 45 is reduced to a lower level. As a result, an insulation structure, which is difficult to be achieved at the through-holes 35 and 45 and the like, which are provided in the floor 11b and the wall surface of the cab 10b and used for providing the hydraulic hoses 32 and 42, and the wiring harness 52, can be realized with a simple structure in which the space surrounded by the floor 11b and the frame 12b is made to be the sound-insulating chamber A. Further, by providing the sound-insulating chamber A, noise in the cab 10b can be further reduced, and operation environment for an operator can be improved, thereby making it possible to improve working efficiency. The embodiments according to the present invention are described in detail thus far, but the shapes of the frames 12a and 12b are not limited to a rectangular shape, and they may include, for example, a circular and an oval shape. Further, part of the frames 12a and 12b, the cover 14, and the sound-insulating members 16 and 17, which form the sound-insulating chamber may have an open portion such as a groove or an opening at a position with less noise from outside. As noise insulating members 16 and 17, urethane foam is cited as an example, but if it has the similar function, glass wool, felt and the like may be suitable. Further, as the sound-insulating members 16 and 17, a rubber tube having a little larger outer diameter than the space to be sound-insulated may be provided in a circular shape, For example, as shown in FIG. 8A, a circular-shaped rubber tube 17a having a plan portion as a sectional shape may be used. In this case, the plan portion of the rubber tube 17a may be placed on the wall surface of the engine room 8 by means of an adhesive. Further, as shown in FIG. 8B, a circular-shaped rubber tube 17b, which has a thick portion 17c formed at one longitudinal end and a slit 17d formed in a longitudinal direction of the thick portion 17c, may be used. In this case, supporting members 55a and 55b, of which end surfaces are located in almost the center of the gap between the rear wall of the cab 10a to be sound-insulated and the engine room 8, and which supports the rubber tube 17b from the inner perimeter side of the rubber tube 17b to be provided, are used. The supporting members 55a and 55b are provided on the wall surface of the engine room 8, and the end surfaces of the supporting members 55a and 55b are inserted into the slit 17d of the rubber tube 17b. An example, in which the hydraulic hoses 32 and 42, the wiring harness 52 and the like are drawn out of the cab 10b via the sound-insulating chamber A at the frame 12b section under the cab 10b, is cited in the second embodiment. However, it goes without saying that the hydraulic hoses 32 and 42, the wiring harness 52 and the like may be drawn out of the cab 10b via the sound-insulating chamber B behind the cab 10a shown in the first embodiment. Further, in the above embodiment, the example with the hydraulic shovel 1 is explained, but the present invention is not limited to the hydraulic shovel 1, and it is applicable to various kinds of working vehicles.

Claims: A working vehicle comprising a frame (12a, 12b, 12d), a cab (10a, 10b, 10d) mounted to the frame so as to be vibratory isolated therefrom, a source of noise provided externally of said cab (10a, 10b, 10d) in a first space, and a sound insulating chamber (A, B, C) for reducing the level of operational noise in the interior of said cab (10a, 10b, 10d), the sound insulating chamber (A, B, C) defining a second space which is physically distinct from the first space and which is located outside of and adjacent to the cab (10a, 10b, 10d) in at least one of the following positions: under the floor (11a) of the cab (10a, 10b, 10d), behind the rear wall of said cab (10a, 10b, 10d) and alongside a side wall of said cab (10a, 10b, 10d), said sound insulating chamber (A, B, C) comprising a wall portion of said cab (10a, 10b, 10d), at least a portion of an existing component of the working vehicle at a side of the first space and at least one closing element of a sound insulating material which completes closing of the sound insulating chamber (A, B, C). The working vehicle according to claim 1, further comprising at least one of hydraulic hoses, wiring harness and control cables extending from the inside of the cab (10a, 10b, 10d) to the outside of the cab (10a, 10b, 10d), wherein the hydraulic hoses, wiring harness or control cables enter the sound insulating chamber (A, B, C) from the cab (10a, 10b, 10d) via through holes (35, 45) and exit the sound insulating chamber (A, B, C) via openings located at a different position from the through holes (35, 45) to the outside.

Inventors: KIMURA KEIJI, NAKADA KUNIAKI, KIMURA, KEIJI, NAKADA, KUNIAKI
Applicants: KOMATSU MFG CO LTD, KOMATSU LTD
Application year: 2000
Main classification: E02F9
IPC codes: E02F9