JP7114535B2 - construction machinery - Google Patents

Description

TECHNICAL FIELD The present invention relates to construction machines such as hydraulic excavators and hydraulic cranes, and more particularly to construction machines having a catwalk on the side of an upper swing structure.

In general, a hydraulic excavator, which is a typical example of construction machinery, consists of a self-propelled undercarriage, an upper swinging body mounted on the lower traveling body so that it can swivel, and a front side of the upper swinging body that can be raised and lowered. It is composed of a working device provided. The upper revolving structure includes a revolving frame that forms a support structure, and an engine that is provided on the revolving frame and drives a hydraulic pump. Among hydraulic excavators, medium-sized or larger hydraulic excavators, for which it is difficult to maintain various equipment mounted on the upper revolving structure from the ground, are provided with catwalks that protrude horizontally from the sides of the revolving frame. (Patent Document 1). By riding on the catwalk, workers can easily perform maintenance on various devices of the upper revolving structure.

Japanese Utility Model Laid-Open Showa 59-19669

By the way, a hydraulic excavator may work in a cold region, and in this cold region, snow may accumulate on the catwalk. When snow accumulates on the catwalk, the scaffolding deteriorates, causing a problem of reduced workability during maintenance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to prevent snow and ice from adhering to a catwalk and to melt accumulated snow and adhering ice. To provide a construction machine capable of improving workability of maintenance by securing good scaffolding.

In order to solve the above-described problems, a construction machine according to the present invention comprises a self-propelled undercarriage and an upper swinging body provided on the undercarriage so as to be able to turn, wherein the upper swinging body is provided with a support. a revolving frame forming a structure; an engine provided on the revolving frame for driving a hydraulic pump; an exhaust pipe provided on the engine for discharging exhaust gas; wherein the exhaust pipe is provided with an outlet through which the exhaust gas discharged from the engine flows out and an inlet into which the exhaust gas flows; The walk extends along the catwalk and has one longitudinal end connected to the outlet of the exhaust pipe and the other longitudinal end connected to the inlet of the exhaust pipe. The exhaust gas pipeline has a snow-melting metal pipe provided on the lower surface of the catwalk, and the snow-melting metal pipe has a portion in contact with the lower surface of the catwalk. The snow-melting metal pipe is formed as a flat deformed metal pipe, and the snow-melting metal pipe includes a forward pipe passage portion extending along the catwalk and having an upstream side in a flow direction connected to the outlet port of the exhaust pipe, and the forward pipe. a return pipe line portion extending in parallel with the forward pipe line portion by folding the downstream side of the pipe portion and connected to the inflow port of the exhaust pipe on the downstream side in the flow direction; and an upstream side of the forward pipe portion. A plurality of bypass pipes are provided at intervals in the longitudinal direction of the catwalk in a state in which an intermediate portion between the folded portion and an intermediate portion between the folded portion of the return pipe portion and the downstream side are connected. It is characterized by being composed of parts .

According to the present invention, it is possible to prevent snow and ice from adhering to the catwalk, melt the accumulated snow and adhered ice, secure a good foothold, and improve the workability of maintenance.

1 is a left side view showing a hydraulic excavator according to an embodiment of the present invention; FIG. FIG. 2 is a plan view of the hydraulic excavator of FIG. 1; Fig. 3 is an enlarged perspective view of the main part of the rear part of the hydraulic excavator as seen from the rear left; 3 is a cross-sectional view of an exhaust pipe and the like as seen from the direction of arrows IV-IV in FIG. 2; FIG. It is a bottom view showing a catwalk and an exhaust gas pipe. FIG. 6 is a cross-sectional view of the catwalk and the snow-melting metal pipe viewed from the direction of arrows VI-VI in FIG. 5;

As a construction machine according to an embodiment of the present invention, a hydraulic excavator will be taken as an example and will be described in detail with reference to FIGS. 1 to 6. FIG. In the present embodiment, the horizontal directions perpendicular to the front and rear directions of the lower traveling body are assumed to be the left and right directions, and the configuration and arrangement of each device and member will be described.

In FIG. 1, a hydraulic excavator 1 as a construction machine includes a crawler-type lower traveling body 2 capable of self-propelled forward and backward; It is configured to include a work device 4 provided on a revolving body 3 so as to be able to move up and down. The upper swing structure 3 includes a swing frame 5, a cab 6, an engine 8, a hydraulic pump 9, an exhaust pipe 12, a catwalk 16, and an exhaust gas pipe line 21, which will be described later.

The swivel frame 5 forms a support structure for the upper swivel 3 . As shown in FIG. 2, the revolving frame 5 includes a bottom plate 5A positioned in the center in the left and right direction and extending in the front and rear directions. A left vertical plate 5B and a right vertical plate 5C extending in the left and right directions, and a left side frame 5D and a right side frame (not shown) extending in the front and rear directions at positions separated from the vertical plates 5B and 5C in the left and right directions. ) and Here, the left side frame 5D corresponds to the side portion of the revolving frame 5. As shown in FIG.

The revolving frame 5 is provided with various devices such as a cab 6 positioned at the front left portion for an operator to ride on, a counterweight 7 positioned at the rear portion for balancing the weight of the working device 4, an engine 8, and the like. It is In addition, a catwalk 16 is provided on a left side frame 5</b>D that is the left side portion of the revolving frame 5 .

As shown in FIG. 2 , the engine 8 is located on the front side of the counterweight 7 and provided on the revolving frame 5 . Also, the engine 8 is mounted in a horizontal position extending in the left and right directions. A hydraulic pump 9 is attached to the left side of the engine 8 . The hydraulic pump 9 is driven by the engine 8 to discharge hydraulic oil as pressure oil. On the right side of the engine 8, a heat exchange device 10 including a radiator, an oil cooler, etc. is provided on the revolving frame 5. As shown in FIG. The engine 8 , hydraulic pump 9 and heat exchange device 10 are covered with an exterior cover 11 . Furthermore, the engine 8 has an exhaust pipe 12 for discharging exhaust gases.

The exhaust pipe 12 is provided on the exhaust side of the engine 8 . The exhaust pipe 12 discharges high-temperature exhaust gas discharged from the engine 8 to the outside of the exterior cover 11 . The exhaust pipe 12 includes an exhaust pipe main body 13 having an upstream end connected to the engine 8, an exhaust gas aftertreatment device 14 positioned above the hydraulic pump 9 and connected to the downstream end of the exhaust pipe main body 13, and an exhaust gas A tail pipe 15 is provided so as to protrude upward from the housing cylinder 14A of the post-processing device 14. As shown in FIG.

An exhaust gas purifying device, a silencer, and the like are housed in the housing cylinder 14A of the exhaust gas aftertreatment device 14 . The exhaust gas purifying device removes harmful substances in the exhaust gas discharged from the engine 8, and the muffler reduces the sound of the exhaust gas.

The tail pipe 15 discharges the exhaust gas discharged from the engine 8 to the outside. As shown in FIG. 4, the tailpipe 15 includes a cylindrical vertical tube portion 15A extending upward from the upper portion of the housing tube body 14A of the exhaust aftertreatment device 14, and a vertical tube portion 15A that bends from the upper portion of the vertical tube portion 15A to form an obliquely curved portion. It is formed as a bent pipe by the inclined tubular portion 15B extending rearward. Further, the tip of the inclined cylindrical portion 15B serves as an exhaust gas outlet portion 15C.

The vertical cylindrical portion 15A is provided with an outflow port 15D positioned at an intermediate portion in the vertical direction. The outflow port 15D is formed as a connection pipe protruding radially outward, for example, rearward, of the vertical tubular portion 15A. Then, the exhaust gas discharged from the engine 8 flows out through the outflow port 15D. One longitudinal end portion 21A of the exhaust gas pipe 21, that is, the upstream side of the forward hose 23 is connected to the outflow port 15D.

In addition, the vertical tube portion 15A is provided with an inflow port 15E located above the outflow port 15D. The inlet 15E is formed as a connection pipe protruding radially outward, for example, rearward, of the vertical tubular portion 15A, similarly to the outlet 15D described above. Then, the exhaust gas that has flowed through the exhaust gas pipe 21 flows into the inflow port 15E. The other longitudinal end 21B of the exhaust gas pipe 21, that is, the downstream side of the return hose 24, is connected to the inflow port 15E.

Further, the vertical tubular portion 15A is provided with a partition plate 15F positioned between the outflow port 15D and the inflow port 15E to block the vertical tubular portion 15A. As a result, the exhaust gas that has flowed into the tail pipe 15 from the exhaust aftertreatment device 14 flows from the outflow port 15D toward the exhaust gas pipe line 21, and is returned from the exhaust gas pipe line 21 to the tail pipe 15 through the inflow port 15E. After that, it is discharged to the outside from the exit portion 15C.

The catwalk 16 is provided on a left side frame 5</b>D, which is a side portion of the revolving frame 5 , and extends horizontally toward the left. The catwalk 16 constitutes a foothold for getting on and off the cab 6 and for performing maintenance on various equipment housed in the exterior cover 11 of the upper swing body 3 .

The catwalk 16 includes a scaffolding plate 16A formed of a trapezoidal plate extending in the front and rear directions, and a reinforcing bending portion 16B extending downward from the periphery of the scaffolding plate 16A. It is composed of As shown in FIG. 5, a metal pipe 22 for melting snow of an exhaust gas pipe 21 is attached to the lower surface 16A2 of the scaffolding board 16A. In addition, at the rear portion of the bent portion 16B, an insertion hole 16C (forward tube in FIG. Only the path portion 22A side is shown) is formed.

Next, the configuration of the exhaust gas pipeline 21 and the flow of the exhaust gas, which are characteristic parts of the present invention, will be described in detail.

The exhaust gas pipe 21 is provided on the catwalk 16 while extending in the front and rear directions along the catwalk 16 . The exhaust gas pipe 21 is connected to the tail pipe 15 of the exhaust pipe 12 and guides the exhaust gas that has flowed into the tail pipe 15 from the engine 8 to the lower surface side of the catwalk 16 . The exhaust gas pipe line 21 has a snow melting metal pipe 22 , an outward hose 23 and a return hose 24 .

As shown in FIGS. 5 and 6, the snow melting metal pipe 22 is attached over the entire lower surface 16A2 of the scaffold board 16A. The snow melting metal pipe 22 is composed of a forward pipeline portion 22A, a folded portion 22B, a return pipeline portion 22C, and a plurality of bypass pipeline portions 22D1, 22D2, 22D3, . . . , 22Dn.

The forward pipeline portion 22A is provided on the lower surface 16A2 side of the scaffold board 16A of the catwalk 16 . The forward pipeline portion 22A extends forward and backward along the catwalk 16 at a position near the left side frame 5D of the revolving frame 5. As shown in FIG. Exhaust gas flows from the rear side to the front side inside the forward pipeline portion 22A. Therefore, the rear upstream end 22A1, which is on the upstream side in the direction in which the exhaust gas flows, is connected to the outflow port 15D of the tailpipe 15 via the outward hose 23. As shown in FIG. On the other hand, the downstream side of the forward pipeline portion 22A is connected to the folded portion 22B in the vicinity of the front portion of the catwalk 16, that is, the cab 6. As shown in FIG. The forward pipeline portion 22A has a midway portion 22A2 between the upstream end 22A1 and the folded portion 22B.

The folded portion 22B connects the downstream side of the forward pipeline portion 22A and the upstream side of the return pipeline portion 22C. The folded portion 22B is positioned at the foremost portion of the snow-melting metal pipe 22 and extends leftward and rightward. The folded portion 22B of the snow-melting metal pipe 22 is formed as a deformed metal pipe whose portion in contact with the lower surface of the catwalk 16 is flat.

Specifically, the folded portion 22B has a flat surface portion 22B1 having a flat upper portion in contact with the lower surface 16A2 of the scaffolding board 16A (see FIG. 6). The folded portion 22B is a semi-circular metal tube having a flat surface portion 22B1, and is integrally attached using means such as welding or bolting while the flat surface portion 22B1 is in contact with the lower surface 16A2 of the scaffolding board 16A. It is As a result, the folded portion 22B can transmit a large amount of heat of the exhaust gas to the scaffolding plate 16A with a wide contact area. Therefore, the scaffolding board 16A of the catwalk 16 can be efficiently warmed by the heat of the exhaust gas passing through the folded portion 22B.

The snow-melting metal pipe 22 includes a forward pipeline portion 22A and a return pipeline portion 22C in addition to the folded portion 22B. The outward pipeline portion 22A and the return pipeline portion 22C are also formed using a deformed metal tube similar to the folded portion 22B.

Here, the passage area of the forward pipeline portion 22A and the folded portion 22B is equal to or larger than the passage area Sn of the thickest bypass pipeline portion 22Dn among the bypass pipeline portions 22D1 to 22Dn. As a result, the exhaust gas can be smoothly circulated to the folded portion 22B separated from the upstream end 22A1 of the forward pipe portion 22A, which is the inlet side of the exhaust gas, and can be smoothly discharged through the folded portion 22B. .

The return pipeline portion 22C is provided on the lower surface 16A2 of the scaffold board 16A together with the forward pipeline portion 22A and the folded portion 22B. The return pipeline portion 22C extends in parallel with the forward pipeline portion 22A by folding back the downstream side of the forward pipeline portion 22A. The return pipe line portion 22C extends rearward from the downstream side (left side) of the folded portion 22B so as to pass through the tip side (left edge side) of the catwalk 16 spaced from the left side frame 5D. The downstream side of the return pipeline portion 22C bends in a crank shape to approach the forward pipeline portion 22A, and then penetrates the bent portion 16B of the catwalk 16 and protrudes rearward. The projecting downstream end 22C1 is connected to the inflow port 15E of the tail pipe 15 via the return hose 24 . The return pipe line portion 22C has a midway portion 22C2 between the folded portion 22B and the downstream end 22C1.

Furthermore, the passage area of the return pipe line portion 22C is set to a value equal to or greater than the passage area Sn of the thickest bypass pipe line portion 22Dn, similarly to the forward pipe line portion 22A and the folded portion 22B. As a result, the exhaust gas that has warmed the catwalk 16 can be smoothly returned to the tail pipe 15 side.

A plurality of bypass pipeline portions 22D1, 22D2, 22D3, . It connects with the middle portion 22C2. The bypass pipe sections 22D1 to 22Dn extend linearly in the left and right directions and are spaced apart in the longitudinal direction of the catwalk 16 in the front and rear directions. Each of the bypass pipeline portions 22D1 to 22Dn is formed as a semicircular deformed metal pipe like the folded portion 22B.

Here, as shown in FIG. 6, the passage areas of the plurality of bypass pipeline portions 22D1 to 22Dn are set to S1 to Sn, respectively. Specifically, a plurality of types of bypass pipe sections 22D1 to 22Dn having different passage areas are used by varying the diameter of the semicircular passage. On top of this, the bypass pipe sections 22D1 to 22Dn are arranged so that the front side of the catwalk 16 on which the cab 6 is provided has a large passage area and the rear side has a small passage area.

That is, among the bypass pipeline portions 22D1 to 22Dn, the bypass pipeline portion 22D1 located at the rear end has the smallest passage area S1, and the bypass pipeline portion 22D2 located on the front side of the bypass pipeline portion 22D1 has the smallest passage area. The passage area S2 is larger (the second smallest) than S1, and the bypass pipe line portion 22Dn positioned at the forefront has the largest passage area Sn (S1<S2<S3<...<Sn).

As a result, a large amount of exhaust gas discharged from the engine 8 can be circulated in the bypass pipeline portion 22Dn (including the folded portion 22B) located on the front side among the bypass pipeline portions 22D1 to 22Dn. Moreover, since the thick bypass pipe portion 22Dn and the like also have a large area in contact with the scaffolding board 16A of the catwalk 16, the heat of the exhaust gas can be efficiently transferred to the scaffolding board 16A. Therefore, the front side of the catwalk 16, which is frequently used for getting on and off the cab 6, can be preferentially heated (warmed) over the rear side of the catwalk 16. - 特許庁

The forward hose 23 connects the tail pipe 15 and the snow melting metal pipe 22 . The forward hose 23 is formed using an elastic member with high heat insulation, such as a resin material (rubber material). The upstream side of the forward hose 23 constitutes one end 21A of the exhaust gas pipe 21 and is connected to the outflow port 15D of the tailpipe 15 . The downstream side of the forward hose 23 is connected to the upstream end 22A1 of the forward pipeline portion 22A that constitutes the snow melting metal pipe 22 provided on the catwalk 16 . Since the forward hose 23 is made of a resin material with high heat insulation, the exhaust gas can be supplied to the snow-melting metal pipe 22 at a high temperature.

On the other hand, like the outward hose 23, the return hose 24 also connects the tail pipe 15 and the snow-melting metal pipe 22, and is formed using an elastic member with high heat insulation, such as a resin material (rubber material). there is The upstream side of the return hose 24 is connected to the downstream end 22C1 of the return pipe line portion 22C that constitutes the snow melting metal pipe 22 provided on the catwalk 16 . The downstream side of the return hose 24 constitutes the other end 21B of the exhaust gas pipe 21 and is connected to the inlet 15E of the tailpipe 15 .

As a result, the exhaust gas that has flowed into the tail pipe 15 is guided to the snow-melting metal pipe 22 via the outward hose 23, and returned from the snow-melting metal pipe 22 to the tail pipe 15 via the return hose 24. 15 is discharged to the outside from an outlet portion 15C.

The hydraulic excavator 1 according to the embodiment has the configuration as described above, and the operation thereof will be described next.

The operator climbs onto the catwalk 16 after climbing onto the tracks of the undercarriage 2 . The operator who climbs the catwalk 16 moves back and forth on the catwalk 16 and gets into the cab 6. - 特許庁An operator who gets into the cab 6 starts the engine 8 and drives the hydraulic pump 9 . In this state, the lower traveling body 2 can be moved forward or backward by operating the operation lever for traveling. On the other hand, by operating a work operation lever (neither of which is shown), the work device 4 can be operated to perform earth and sand excavation work or the like.

The hydraulic excavator 1 may work in cold regions, and snow may accumulate on the catwalk 16 in this cold region. In this case, if snow accumulates or ice adheres to the catwalk 16, the scaffolding becomes poor, so it takes time to get into the cab 6, and there is a risk that workability during maintenance will deteriorate.

Therefore, according to the embodiment, the tail pipe 15 constituting the exhaust pipe 12 is provided with an outflow port 15D through which the exhaust gas discharged from the engine 8 flows out and an inflow port 15E into which the exhaust gas flows. . The catwalk 16 has an end 21A extending along the catwalk 16, one end 21A in the length direction is connected to the outlet 15D of the tail pipe 15, and the other end 21B in the length direction is connected to the flow of the tail pipe 15. An exhaust gas line 21 is provided which is connected to the inlet 15E. The exhaust gas pipeline 21 has a snow melting metal pipe 22 attached to the lower surface 16A2 of the catwalk 16 (scaffold board 16A). The snow-melting metal pipe 22 is formed as a deformed metal pipe whose portion in contact with the lower surface 16A2 of the catwalk 16 is flat.

Therefore, the exhaust gas pipe 21 passes the exhaust gas discharged from the engine 8 through the snow-melting metal pipe 22, thereby transmitting the heat of the exhaust gas to the catwalk 16, thereby removing snow and ice on the catwalk 16. can melt. Also, it is possible to prevent snow and ice from adhering to the catwalk 16 .

As a result, even in a cold region or when it is snowing, it is possible to secure a good foothold when getting into and out of the cab 6 and during maintenance, and workability can be improved. In addition, since the exhaust gas is used as the heat source, a separate device such as a heater is not required, and the configuration can be simplified.

In particular, the snow-melting metal pipe 22 is attached to the lower surface of the catwalk 16 and is formed as a deformed metal pipe whose portion in contact with the lower surface of the catwalk 16 is flat. Thereby, the contact area with the lower surface 16A2 of the catwalk 16 can be increased. Therefore, the heat of the exhaust gas that has passed through the snow-melting metal pipe 22 of the exhaust gas pipe 21 can be efficiently transmitted to the entire catwalk 16 .

Further, according to the embodiment, the snow-melting metal pipe 22 is composed of a forward pipeline portion 22A, a return pipeline portion 22C, and a plurality of bypass pipeline portions 22D1 to 22Dn. The forward pipeline portion 22A extends along the catwalk 16 and is connected to the outlet port 15D of the exhaust pipe 12 on the upstream side in the flow direction. The return pipeline portion 22C extends in parallel with the forward pipeline portion 22A by folding back the downstream side of the forward pipeline portion 22A, and is connected to the inlet 15E of the exhaust pipe 12 on the downstream side in the flow direction. Each of the bypass pipeline portions 22D1 to 22Dn has a midway portion 22A1 between the upstream side of the forward pipeline portion 22A and the folded portion 22B, and a midway portion 22B1 between the downstream side and the folded portion 22B of the return pipeline portion 22C. are concatenated. In this state, a plurality of bypass pipeline portions 22D1 to 22Dn are provided at intervals in the longitudinal direction of the catwalk 16. As shown in FIG.

Therefore, the snow-melting metal pipe 22 can be arranged over the entire catwalk 16 by the forward pipeline portion 22A, the folded portion 22B, the return pipeline portion 22C, and the plurality of bypass pipeline portions 22D1 to 22Dn. Therefore, the contact area with the lower surface 16A2 of the catwalk 16 can be increased. As a result, the entire catwalk 16 can be effectively warmed by passing the exhaust gas through the snow-melting metal pipe 22 of the exhaust gas pipe 21 .

Furthermore, according to the embodiment, each of the bypass pipeline portions 22D1 to 22Dn of the metal pipe 22 for melting snow has a plurality of types ( S1<S2<S3<...<Sn) is used. As a result, a large amount of exhaust gas discharged from the engine 8 can be circulated in the bypass pipe line portion 22Dn positioned on the front side among the bypass pipe line portions 22D1 to 22Dn. Moreover, since the thick bypass pipe portion 22Dn also has a large area in contact with the scaffolding board 16A of the catwalk 16, the heat of the exhaust gas can be efficiently transferred to the scaffolding board 16A. Therefore, the front side of the catwalk 16, which is frequently used for getting on and off the cab 6, can be preferentially heated (warmed) over the rear side of the catwalk 16. - 特許庁

In the embodiment, the case where the snow-melting metal pipe 22 of the exhaust gas pipe 21 is fixed to the catwalk 16 by means of welding, bolting, or the like has been described as an example. However, the present invention is not limited to this, and for example, the snow melting metal pipe may be integrally formed with the catwalk. That is, it is sufficient that the heat of the exhaust gas is transferred to the catwalk.

In the embodiment, a case where a plurality of types of bypass pipeline portions 22D1 to 22Dn of the metal pipe 22 for melting snow are used with different passage areas has been described as an example. However, the present invention is not limited to this, and for example, the passage area of each bypass pipe line portion may be the same.

In the embodiment, the case where the exhaust gas pipe line 21 is connected to the tail pipe 15 of the exhaust pipe 12 has been described as an example. However, the present invention is not limited to this, and for example, the exhaust gas pipeline may be connected to a portion other than the tailpipe that constitutes the exhaust pipe, for example, the exhaust pipe main body.

In the embodiment, the hydraulic excavator 1 has been described as an example of the construction machine. However, the present invention is not limited to this, and can be widely applied to other construction machines such as hydraulic cranes.

1 Hydraulic excavator (construction machinery)
2 lower running body 3 upper revolving body 5 revolving frame 5D left side frame (side part)
6 Cab 8 Engine 9 Hydraulic Pump 12 Exhaust Pipe 15D Outlet 15E Inlet 16 Catwalk 16A2 Lower Surface 21 Exhaust Gas Pipe Line 21A One End 21B The Other End 22 Snow Melting Metal Pipe 22A Forward Pipe Line 22A2, 22C2 Midway Portion 22B Folded portion 22B1 Flat surface portion 22C Return pipeline portion 22D1, 22D2, 22D3, . . . , 22Dn Bypass pipeline portion S1, S2, S3, .

Claims (2)

It consists of a self-propellable undercarriage and an upper revolving body rotatably provided on the undercarriage,
The upper swing structure includes a swing frame forming a support structure, an engine provided on the swing frame for driving a hydraulic pump, an exhaust pipe provided on the engine for discharging exhaust gas, and a side of the swing frame. A construction machine comprising a catwalk provided horizontally overhanging the part,
The exhaust pipe is provided with an outlet through which the exhaust gas discharged from the engine flows out and an inlet through which the exhaust gas flows,
The catwalk extends along the catwalk, has one longitudinal end connected to the outlet of the exhaust pipe, and has the other longitudinal end connected to the inlet of the exhaust pipe. is provided with an exhaust gas line connected to
The exhaust gas pipeline has a snow melting metal pipe provided on the lower surface of the catwalk,
The snow-melting metal pipe is formed as a deformed metal pipe having a flat portion in contact with the lower surface of the catwalk ,
The snow-melting metal pipe extends along the catwalk, and includes a forward pipeline portion connected upstream in the flow direction to the outlet port of the exhaust pipe, and a downstream side of the forward pipeline portion that is folded back to form the forward pipeline. a return pipeline portion extending in parallel with the pipeline portion and connected to the inflow port of the exhaust pipe on the downstream side in the flow direction; A plurality of bypass pipe line portions are provided at intervals in the length direction of the catwalk in a state in which the turn-back portion of the return pipe line portion and the midway portion between the downstream side are connected to each other. and construction machinery. 2. The bypass pipe portion of the snow-melting metal pipe according to claim 1 , wherein a plurality of types with different passage areas are used so that the front side where the cab is provided has a large passage area. construction equipment.

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