JP2021143614A - Construction machine - Google Patents

Abstract

To enable a reduction in the temperature of exhaust gas by mixing low-temperature air with the high-temperature exhaust gas.SOLUTION: On an upper face 8C of an external cover 8, a diffuser 17 is provided. The diffuser 17 includes a peripheral wall part 21 rising up from a position encircling the periphery of an upper part opening 8D of the exterior cover 8, a top plate part 22 connected to the peripheral wall part 21 for covering an area above a connection pipe 16, and an exhaust port 23 for exhausting exhaust gas jetted via the connection pipe 16 from a tail pipe 15 and guided by the peripheral wall part 21 and the top plate part 22. Besides, a first peripheral wall 21A located on the opposite side to the exhaust port 23 across the upper part opening 8D is formed as a flat plate, and the top plate part 22 is formed as a flat plate extending obliquely upward from the first peripheral wall 21A.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to construction machinery such as a hydraulic excavator equipped with an exhaust gas aftertreatment device.

In general, a hydraulic excavator as a typical example of a construction machine is provided with an engine (diesel engine) as a power source in a machine room covered with an exterior cover. Further, an exhaust gas aftertreatment device for treating the exhaust gas discharged from the engine is connected to the exhaust pipe of the engine. Further, in the exhaust gas aftertreatment device, a tail pipe for ejecting the treated exhaust gas projects toward the upper surface of the exterior cover.

In recent years, due to the growing awareness of the problem of environmental pollution, the exhaust gas of the engine mounted on the hydraulic excavator is also being cleaned. Here, as the exhaust gas aftertreatment device, for example, a particulate matter collecting device (DPF: Diesel Particulate Filter) that collects and removes particulate matter (PM: Particulate Matter) contained in the exhaust gas with a filter is used. Are known. When a certain amount of particulate matter is collected in the filter, this particulate matter collection device regenerates the filter by burning and removing the accumulated particulate matter, and maintains the collection performance of the particulate matter. ing.

However, when the particulate matter deposited on the filter is burned, the temperature of the exhaust gas reaches about 600 degrees. On the other hand, it is not preferable that the high-temperature exhaust gas is discharged to the outside at a high temperature. Therefore, a hydraulic excavator having an exhaust gas aftertreatment device is provided with a device for reducing the temperature of the exhaust gas. The exhaust gas reducing device includes an exhaust port provided on the upper surface of the exterior cover and a cover member provided around the exhaust port. On this basis, the cover member is provided with an opening for guiding the air inside the machine or the air outside the machine into the cover member (Patent Document 1). As a result, in Patent Document 1, the temperature is lowered by merging low-temperature air with the high-temperature exhaust gas discharged from the exhaust port.

Japanese Unexamined Patent Publication No. 2016-125432

By the way, in Patent Document 1, since low temperature air is only circulated around the exhaust gas discharged from the exhaust port, it is difficult for the low temperature air to be mixed with the high temperature exhaust gas, and the temperature of the exhaust gas is high. There is a problem that it is difficult to significantly reduce.

An object of an embodiment of the present invention is to provide a construction machine capable of reducing the temperature of an exhaust gas by mixing a low temperature air with a high temperature exhaust gas.

One embodiment of the present invention is an exhaust gas post-treatment that is provided by connecting to an engine arranged in a machine room covered with an exterior cover and an exhaust pipe of the engine to process the exhaust gas discharged from the engine. It is inserted through the device, a tail tube that protrudes from the exhaust gas aftertreatment device toward the upper surface portion of the exterior cover and ejects the treated exhaust gas, and an upper opening formed on the upper surface portion of the exterior cover. In a construction machine including a connecting pipe extending downward from the upper surface portion of the exterior cover and into which the tail tube is inserted, the upper surface portion of the exterior cover is provided with a diffuser. The diffuser is ejected from the tail tube through the connecting tube, a peripheral wall portion that rises from a position surrounding the upper opening, a top plate portion that is connected to the peripheral wall portion and covers the upper part of the connecting tube, and the tail tube. A first having a peripheral wall portion and an exhaust port for discharging exhaust gas guided by the top plate portion, which is a part of the peripheral wall portion and is located on the opposite side of the upper opening to the exhaust port. The one peripheral wall is formed as a flat plate, and the top plate portion is a flat plate extending diagonally upward from the first peripheral wall.

According to one embodiment of the present invention, low temperature air can be mixed with high temperature exhaust gas, and the temperature of the exhaust gas can be reduced.

It is a left side view which shows the hydraulic excavator which concerns on 1st Embodiment of this invention. It is sectional drawing which looked at the machine room of the upper swing body from the direction of arrow II-II in FIG. It is sectional drawing which looked at the upper surface part of the exterior cover, the exhaust gas aftertreatment device, the tail pipe, the diffuser, etc. from the direction of arrow III-III in FIG. It is a perspective view which shows the state which attached the diffuser to the upper surface part of the exterior cover. It is a perspective view which shows the state which the diffuser is removed from the upper surface part of the exterior cover. FIG. 5 is a cross-sectional view of the diffuser according to the second embodiment of the present invention as viewed from the same position as in FIG. 3 together with the upper surface portion of the exterior cover, the exhaust gas aftertreatment device, the tail pipe, and the like. FIG. 5 is a perspective view of the diffuser according to the third embodiment of the present invention as viewed from the same position as in FIG. 4 together with the upper surface portion of the exterior cover.

Hereinafter, as a typical example of the construction machine according to the embodiment of the present invention, a hydraulic excavator equipped with an exhaust gas aftertreatment device will be taken as an example, and the details will be described with reference to the accompanying drawings.

First, FIGS. 1 to 5 show a first embodiment of the present invention. In FIG. 1, the hydraulic excavator 1 constitutes a crawler type construction machine. The hydraulic excavator 1 includes a self-propelled crawler-type lower traveling body 2, an upper rotating body 3 mounted on the lower traveling body 2 so as to be able to swivel, and an operation of raising and lowering on the front portion of the upper swivel body 3. Is provided so as to be possible, and is composed of a work device 4 for excavating earth and sand and the like.

The swivel frame 5 forms a support structure for the upper swivel body 3. As shown in FIG. 2, the swivel frame 5 is a bottom plate 5A made of a thick steel plate or the like extending in the front-rear direction, and a left vertical plate erected on the bottom plate 5A and extending in the front-rear direction at a predetermined interval in the left-right direction. 5B, right vertical plate 5C, left side frame 5D, right side frame 5E, bottom plate 5A, each vertical plate 5B, 5C arranged at intervals on the outside of each vertical plate 5B, 5C in the left-right direction and extending in the front-rear direction. It is configured to include a plurality of overhanging beams 5F (only two of which are shown in FIG. 2) supporting the side frames 5D and 5E, respectively. The swivel frame 5 closes the lower side of the machine room 9, which will be described later.

The counterweight 6 is provided at the rear of the left and right vertical plates 5B and 5C forming the swivel frame 5 (see FIG. 1). The counterweight 6 balances the weight with the working device 4 and is formed as a heavy object.

The cab 7 is provided on the left front side of the swivel frame 5. The cab 7 is for the operator to board, and for example, a driver's seat on which the operator sits, an operation lever for traveling, and an operation lever for work (none of which are shown) are arranged inside the cab 7. ..

The exterior cover 8 covers equipment including an engine 10, a hydraulic pump 11, a heat exchange device 12, and an exhaust gas aftertreatment device 14, which will be described later. The exterior cover 8 is located between the counterweight 6 and the cab 7 and is provided on the swivel frame 5. Specifically, the exterior cover 8 covers the left side portion 8A rising from the left side frame 5D of the swivel frame 5 so as to cover the left side of the heat exchange device 12, and the swivel frame 5 so as to cover the right side of the hydraulic pump 11 and the like. 8B on the right side rising from the right side frame 5E, and 8C on the upper surface extending horizontally between the upper part of the left side 8A and the upper part of the right side 8B so as to cover the upper side of the engine 10 and the like. Is configured to include. The left surface portion 8A is provided with a vent for allowing outside air to flow in toward the machine room 9 as cooling air.

The upper surface portion 8C is formed as, for example, a flat plate-like body. The upper surface portion 8C is provided with an upper opening 8D located directly above the tail tube 15. As shown in FIGS. 3 and 5, the upper opening 8D is formed as a circular opening having an inner diameter dimension larger than the outer diameter dimension of the tail tube 15. A connecting pipe 16 described later is inserted through the upper opening 8D. Further, a plurality of, for example, four screw holes 8E are provided around the upper opening 8D. For example, a welding nut or the like is used for the screw hole 8E.

The machine room 9 is arranged in front of the counterweight 6. The machine room 9 is formed as a rectangular parallelepiped space long in the left-right direction covered by the swivel frame 5 and the exterior cover 8. Further, the machine room 9 includes a cooling air inflow chamber 9A located between the left surface portion 8A of the exterior cover 8 and the heat exchange device 12, an engine room 9B located between the heat exchange device 12 and the fire wall 13. It is partitioned into a pump chamber 9C located between the fire wall 13 and the right surface portion 8B.

The engine 10 is composed of a diesel engine and is arranged in the engine room 9B of the machine room 9. The engine 10 is provided in a horizontal position extending in the left-right direction on the rear side of the turning frame 5. The engine 10 is provided with an exhaust pipe 10A for exhausting the exhaust gas, and the exhaust pipe 10A is provided with an exhaust gas aftertreatment device 14 described later. A cooling fan 10B is provided on the left side of the engine 10 at a position facing the heat exchange device 12.

The hydraulic pump 11 is provided on the right side of the engine 10 so as to be located in the pump chamber 9C, and is driven by the engine 10. The hydraulic pump 11 discharges the hydraulic oil supplied from the hydraulic oil tank 27, which will be described later, as pressure oil toward the control valve device (not shown).

The heat exchange device 12 is provided so as to face the upstream side of the cooling fan 10B in the flow direction of the cooling air (flow direction from left to right in FIG. 2). The heat exchange device 12 includes, for example, a radiator for cooling engine cooling water and an oil cooler for cooling hydraulic oil. The heat exchange device 12 constitutes a partition member that partitions the area on the left side of the machine room 9 into a cooling air inflow chamber 9A and an engine chamber 9B.

The firewall 13 is located around the hydraulic pump 11 and is provided between the swivel frame 5 and the upper surface portion 8C of the exterior cover 8. The firewall 13 shields the engine 10 from the hydraulic pump 11, and constitutes a partition member that partitions the area on the right side of the machine room 9 into the engine room 9B and the pump room 9C. The firewall 13 is formed so as to straddle the mounting base of the hydraulic pump 11 with respect to the engine 10, for example, by bending a plurality of steel plates and fixing them to each other. As a result, the firewall 13 can prevent the leaked hydraulic oil from scattering to the engine 10 side (engine chamber 9B side) even when the hydraulic oil leaks around the hydraulic pump 11.

The exhaust gas aftertreatment device 14 is provided so as to be connected to the exhaust pipe 10A of the engine 10 and treats the exhaust gas discharged from the engine 10. An example of the configuration, layout, and the like of the exhaust gas aftertreatment device 14 will be described. The exhaust gas aftertreatment device 14 is provided so as to extend in the front-rear direction at a position on the upper right side of the engine 10 above the hydraulic pump 11. As shown in FIG. 3, the exhaust gas aftertreatment device 14 has a cylindrical case 14A formed as a cylindrical body extending in the front-rear direction, and the tubular case 14A projecting outward in the radial direction from the front side position toward the left side. It includes an inflow pipe 14B (see FIG. 2) and a tail pipe 15 which will be described later and is provided at a rear position of the cylindrical case 14A so as to extend in the vertical direction. The tubular case 14A is arranged near the lower side of the upper surface portion 8C of the exterior cover 8. Further, the inflow pipe 14B is connected to the exhaust pipe 10A of the engine 10.

Here, in the tubular case 14A of the exhaust gas aftertreatment device 14, a treatment device for purifying the exhaust gas, for example, in order to collect and remove particulate matter (PM) contained in the exhaust gas. A particulate matter collection device (not shown) composed of an oxidation catalyst and a filter is housed. In addition to the particulate matter collection device, the tubular case 14A also contains a NOx purification device that purifies nitrogen oxides (NOx) contained in the exhaust gas using an aqueous urea solution, and reduces the noise of the exhaust gas. It can accommodate a muffling device (exhaust muffler) and the like. The tubular case 14A is attached to the right side portion of the engine 10 together with the hydraulic pump 11 via, for example, the attachment bracket 14C.

Here, the particulate matter collector housed in the tubular case 14A collects the particulate matter contained in the exhaust gas with a filter. When a certain amount of particulate matter is collected in the filter, this particulate matter collection device regenerates the filter by burning and removing the accumulated particulate matter, and maintains the collection performance of the particulate matter. ing. For example, when the particulate matter deposited on the filter is burned, the temperature of the exhaust gas reaches about 600 degrees.

The tail pipe 15 projects from the exhaust gas aftertreatment device 14 toward the upper surface portion 8C of the exterior cover 8 and ejects the treated exhaust gas. The tail pipe 15 is provided so as to project upward at a rear position of the cylindrical case 14A forming the exhaust gas aftertreatment device 14. The tail tube 15 is formed of a cylindrical body and is arranged directly below the upper opening 8D provided on the upper surface portion 8C of the exterior cover 8. The upper part of the tail tube 15 is inserted into a connecting tube 16 which will be described later. That is, the outer diameter dimension D of the tail pipe 15 is set to a value smaller than the inner diameter dimension d of the connecting pipe 16. As a result, an annular space 24, which will be described later, is formed between the tail pipe 15 and the connecting pipe 16 for allowing the air in the machine room 9 to flow into the diffuser 17.

The connecting pipe 16 is inserted through the upper opening 8D of the exterior cover 8 and extends downward from the upper surface portion 8C of the exterior cover 8. A tail tube 15 is inserted into the connecting tube 16 from below. The connecting pipe 16 is formed as a cylindrical body extending downward from the flange portion 18 of the diffuser 17. As shown in FIG. 3, the upper end of the connecting pipe 16 is fitted into the circular opening 18A of the flange portion 18. On the other hand, the lower end of the connecting pipe 16 extending downward from the circular opening 18A surrounds the tail pipe 15. Here, the connecting pipe 16 is formed as, for example, a cylindrical body extending in the vertical direction, and the inner diameter dimension d that is uniform over the entire length is larger than the outer diameter dimension D of the tail pipe 15 (d). > D). As a result, the connecting pipe 16 forms an annular space 24 described later with the tail pipe 15. The connecting pipe 16 may be attached to the upper surface portion 8C so as to be coaxial with the upper opening 8D of the exterior cover 8.

Next, the configuration of the diffuser 17, which is a feature of the present embodiment, and the flow of exhaust gas and the like will be described in detail.

The diffuser 17 is provided on the upper surface portion 8C of the exterior cover 8. The diffuser 17 is provided around the open end of the connecting pipe 16 described later. The diffuser 17 guides the exhaust gas ejected from the tail pipe 15 to the outside of the machine room 9. The diffuser 17 includes a flange portion 18, a peripheral wall portion 21, a top plate portion 22, and an exhaust port 23, which will be described later.

As shown in FIGS. 4 and 5, the flange portion 18 is attached to the upper surface portion 8C of the exterior cover 8. The flange portion 18 is formed as, for example, a rectangular plate body elongated in the left-right direction. A circular opening 18A to which the connecting pipe 16 is attached is provided in the center of the flange portion 18. Further, the flange portion 18 is provided with two bolt insertion holes 18B in the front-rear direction at intervals in the front-rear direction, for a total of four bolt insertion holes 18B, on both sides of the circular opening 18A in the longitudinal direction. The flange portion 18 can be attached to the upper surface portion 8C by screwing the bolts 19 inserted into the bolt insertion holes 18B into the screw holes 8E of the exterior cover 8.

The peripheral wall portion 21 is formed as, for example, a rectangular cylindrical body, and rises from the upper surface of the flange portion 18. The peripheral wall portion 21 is formed from the first peripheral wall 21A to the fourth peripheral wall 21D. The first peripheral wall 21A is a part of the peripheral wall portion 21, and is located on the opposite side to the exhaust port 23, for example, the front side with the upper opening 8D interposed therebetween. The first peripheral wall 21A is formed as a rectangular flat plate elongated in the lateral direction. Further, the first peripheral wall 21A is arranged at a position separated from the upper opening 8D on the front side.

The second peripheral wall 21B is formed as a flat plate connected to one end of the first peripheral wall 21A, for example, the left end. The second peripheral wall 21B is formed so as to extend upward from the upper surface of the flange portion 18 at a position separated to the left side from the upper opening 8D. The upper side of the second peripheral wall 21B is a hypotenuse portion 21B1 extending diagonally upward from the upper part of the first peripheral wall 21A toward the rear side.

On the other hand, the third peripheral wall 21C is formed as a flat plate connected to the other end portion of the first peripheral wall 21A, for example, the right end portion. The third peripheral wall 21C is formed so as to extend upward from the upper surface of the flange portion 18 at a position separated to the right side from the upper opening 8D. The upper side of the third peripheral wall 21C is a hypotenuse portion 21C1 extending diagonally upward from the upper part of the first peripheral wall 21A toward the rear side, similarly to the second peripheral wall 21B.

Further, the fourth peripheral wall 21D is arranged on the exhaust port 23 side with the upper opening 8D interposed therebetween, for example, on the rear side with a space in the front-rear direction from the first peripheral wall 21A. The fourth peripheral wall 21D is formed as a rectangular flat plate having a size smaller in the vertical direction than the first peripheral wall 21A, and rises from the upper surface of the flange portion 18 like the first peripheral wall 21A. Further, both ends of the fourth peripheral wall 21D in the length direction are connected to the rear end of the second peripheral wall 21B and the rear end of the third peripheral wall 21C.

As a result, the peripheral wall portion 21 is formed as a rectangular frame body separated from the upper opening 8D. As shown in FIG. 5, the distance between the first peripheral wall 21A and the fourth peripheral wall 21D is set to the dimension L1, and the distance between the second peripheral wall 21B and the third peripheral wall 21C is set to the dimension L2. Both the dimension L1 and the dimension L2 are set to a value larger than the inner diameter dimension d of the connecting pipe 16 (L1> d, L2> d). Further, the upper side of the second peripheral wall 21B is a hypotenuse portion 21B1 extending diagonally upward from the upper part of the first peripheral wall 21A toward the rear side. Similarly, the upper side of the third peripheral wall 21C is a hypotenuse portion 21C1 extending diagonally upward from the upper part of the first peripheral wall 21A toward the rear side.

Here, the peripheral wall portion 21 sets the distance dimension L1 between the first peripheral wall 21A and the fourth peripheral wall 21D and the distance dimension L2 between the second peripheral wall 21B and the third peripheral wall 21C to a value larger than the inner diameter dimension d of the connecting pipe 16. By setting, the passage area around the open end of the connecting pipe 16 is sharply increased. As a result, the diffuser 17 reduces the pressure around the open end of the connecting pipe 16 to generate a reverse flow from the top plate portion 22 side to the peripheral wall portion 21 side (around the open end of the connecting pipe 16). There is. In this case, what is important is the position of the first peripheral wall 21A in contact with the lower part of the top plate portion 22, and the first peripheral wall 21A should be installed at a position distant from the opening end of the connecting pipe 16. Therefore, the exhaust gas can be guided to the low-pressure area 26 described later along the top plate portion 22 and the first peripheral wall 21A.

Further, the peripheral wall portion 21 is formed as a rectangular frame body surrounding the circular connecting pipe 16. Therefore, the distance between the corner of the frame and the connection pipe 16 is wide, and the distance between the intermediate position between the adjacent corners and the connection pipe 16 is narrow between the connection pipe 16 and the peripheral wall portion 21. In this way, in a structure in which the distance between the connecting pipe 16 and the peripheral wall portion 21 is different in the circumferential direction, the pressure (negative pressure) generated between the connecting pipe 16 and the peripheral wall portion 21 can be dispersed, and is disturbed. A stream can be formed. This turbulent flow positively mixes the exhaust gas flowing from the connecting pipe 16 toward the exhaust port 23 with the cold air.

In the present embodiment, since the diffuser 17 is configured to discharge the exhaust gas in the rear direction of the upper swirl body 3, the first peripheral wall 21A on the side opposite to the discharge direction is separated from the open end of the connecting pipe 16. Is important. That is, when the diffuser is configured to discharge the exhaust gas in the right direction of the upper swirl body, it is important to separate the left wall on the side opposite to the discharge direction from the exhaust port.

The top plate portion 22 is formed from the upper portion of the first peripheral wall 21A forming the peripheral wall portion 21 along the hypotenuse portion 21B1 of the second peripheral wall 21B and the hypotenuse portion 21C1 of the third peripheral wall 21C, along with the second peripheral wall 21B and the third peripheral wall 21C. It is formed as a rectangular flat plate extending to the upper end of the. That is, the top plate portion 22 is formed as an inclined surface having a low front side and a high rear side.

The exhaust port 23 discharges the exhaust gas ejected from the tail pipe 15 via the connecting pipe 16 and guided by the peripheral wall portion 21 and the top plate portion 22. The exhaust port 23 is formed as a rectangular opening surrounded by a second peripheral wall 21B, a third peripheral wall 21C, a fourth peripheral wall 21D, and a top plate portion 22. The exhaust port 23 is opened toward the rear, for example.

The annular space 24 is formed between the tail tube 15 and the connecting tube 16. The annular space 24 is a passage through which the air in the machine room 9 (engine room 9B) flows into the connecting pipe 16 by the ejector effect using the exhaust gas ejected upward from the tail pipe 15.

In the diffuser 17 configured in this way, as shown in FIG. 5, the connecting pipe 16 is inserted into the upper opening 8D provided in the upper surface portion 8C of the exterior cover 8 from above, and the flange portion 18 hits the upper surface portion 8C. Get in touch. In this state, the bolts 19 are inserted into the bolt insertion holes 18B provided in the flange portion 18, and the bolts 19 are screwed into the screw holes 8E. As a result, as shown in FIG. 4, the diffuser 17 can be integrally attached to the upper surface portion 8C of the exterior cover 8. Further, the connecting pipe 16 can form an annular space 24 with the tail pipe 15 by surrounding the tail pipe 15 with a gap.

Next, the flow of exhaust gas and the like in the tail pipe 15 and the diffuser 17 will be described with reference to FIG.

First, as shown by arrow A, the exhaust gas ejected from the tail pipe 15 collides with the vicinity of the center of the top plate portion 22 located directly above. As a result, a high pressure area 25 is formed in the diffuser 17 near the center of the top plate portion 22 due to the collision pressure of the exhaust gas. On the other hand, as shown by arrow B, the exhaust gas ejected from the tail pipe 15 draws the air in the machine room 9 (engine room 9B) into the connecting pipe 16 through the annular space 24. Then, the air drawn into the connecting pipe 16 through the annular space 24 is ejected into the diffuser 17 together with the exhaust gas. In this case, since the air in the engine chamber 9B is sufficiently lower than the exhaust gas, the air drawn into the connecting pipe 16 from the engine chamber 9B flows together with the exhaust gas to become the exhaust gas. Takes heat and lowers the temperature.

Here, the peripheral walls 21A to 21D of the peripheral wall portions 21 constituting the diffuser 17 are arranged at positions separated from the upper opening 8D (opening end of the connecting pipe 16) of the exterior cover 8 to the outside in the radial direction of the tail pipe 15. It is installed. As a result, between the open end of the connecting pipe 16 and the peripheral walls 21A to 21D, there is an expanded portion in which the passage area rapidly expands.

Therefore, when the exhaust gas and the air circulate in the connecting pipe 16 and are ejected upward together from the connecting pipe 16, the ejected exhaust gas and the air are discharged from the connecting pipe 16 as shown by arrow C. It draws in the air around the (expansion part). As a result, a low pressure area 26 is formed in the widened portion between the connecting pipe 16 and the peripheral walls 21A to 21D.

When the high-pressure area 25 and the low-pressure area 26 are formed in the diffuser 17 in this way, the exhaust gas and the air flow from the high-pressure area 25 toward the low-pressure area 26, as shown by arrow E. Then, the exhaust gas and the air are positively mixed with each other by generating a flow in the arrow C direction and a flow in the arrow E direction, which are partially different from the normal exhaust gas flow. As a result, the temperature of the high-temperature exhaust gas is lowered by the relatively low-temperature air in the engine chamber 9B. As shown by arrow F, the exhaust gas or the like whose temperature has been lowered is discharged to the outside from the exhaust port 23 of the diffuser 17.

As shown in FIG. 2, the hydraulic oil tank 27 is located on the front side of the pump chamber 9C and is provided on the swivel frame 5. The hydraulic oil tank 27 stores hydraulic oil to be supplied to various hydraulic actuators mounted on the hydraulic excavator 1. Further, a fuel tank (not shown) for storing fuel to be supplied to the engine 10 is arranged on the front side of the hydraulic oil tank 27.

The hydraulic excavator 1 according to the present embodiment has the above-described configuration, and next, the operation of the hydraulic excavator 1 will be described.

First, the operator gets on the cab 7 and sits in the driver's seat. By operating the traveling operation lever in this state, the lower traveling body 2 can be driven to move the hydraulic excavator 1 to the work site. In addition, the operator can operate the work device 4 and the like to perform excavation work of earth and sand by operating the operation lever for work.

When the hydraulic excavator 1 is in operation, the exhaust gas discharged from the engine 10 is purified by the exhaust gas aftertreatment device 14. Specifically, the particulate matter collection device of the exhaust gas aftertreatment device 14 is composed of an oxidation catalyst and a filter for collecting and removing the particulate matter (PM) contained in the exhaust gas. Further, when the collected particulate matter is burned and removed, the temperature of the exhaust gas at this time may be as high as 600 degrees or more, for example.

However, according to the present embodiment, the diffuser 17 is provided on the upper surface portion 8C of the exterior cover 8. Further, the diffuser 17 is provided via a peripheral wall portion 21 that rises from a position surrounding the upper opening 8D of the exterior cover 8, a top plate portion 22 that connects to the peripheral wall portion 21 and covers the upper part of the connecting pipe 16, and a connecting pipe 16. It is provided with an exhaust port 23 for discharging the exhaust gas ejected from the tail pipe 15 and guided by the peripheral wall portion 21 and the top plate portion 22. On this, the first peripheral wall 21A located on the opposite side of the upper opening 8D from the exhaust port 23 is formed as a flat plate, and the top plate portion 22 is formed as a flat plate extending diagonally upward from the first peripheral wall 21A. Has been done.

Therefore, the high pressure area 25 can be formed on the top plate portion 22 side by colliding the exhaust gas ejected from the connecting pipe 16 with the top plate portion 22 made of a flat plate. Further, a low pressure area 26 can be formed in the widened portion between the connecting pipe 16 and the first peripheral wall 21A. As a result, a part of the exhaust gas can be circulated (backflow) from the high pressure area 25 to the low pressure area 26, and the exhaust gas and the low temperature air drawn from the engine chamber 9B are positively mixed in the diffuser 17. be able to. As a result, the temperature of the exhaust gas can be reduced because the low-temperature air on the engine chamber 9B side can be mixed with the high-temperature exhaust gas.

The diffuser 17 has a flange portion 18 attached to the upper surface portion 8C of the exterior cover 8, and the peripheral wall portion 21 rises from the flange portion 18. Thereby, for example, the diffuser 17 can easily attach the peripheral wall portion 21 to the upper surface portion 8C by screwing the bolt 19 inserted through the flange portion 18 to the upper surface portion 8C.

Next, FIG. 6 shows a second embodiment of the present invention. The feature of this embodiment is that the top plate portion of the diffuser has a collision plate extending in the horizontal direction at a position where the exhaust gas discharged from the exhaust port collides. In the second embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 6, the diffuser 31 according to the second embodiment includes a peripheral wall portion 33, a top plate portion 34, and an exhaust port 35, similarly to the diffuser 17 according to the first embodiment. The top plate portion 34 has a collision plate 34A at a position where the exhaust gas discharged from the connecting pipe 16 collides.

The collision plate 34A has a gas receiving portion 34A1 located directly above the connecting pipe 16 (tail pipe 15) and extending in the horizontal direction. Therefore, the collision plate 34A can collide the exhaust gas or the like with the gas receiving portion 34A1 from the lower front surface, and can increase the collision pressure to increase the pressure in the high pressure area 36. As a result, the pressure difference between the high pressure area 36 and the low pressure area 26 becomes large, so that the exhaust gas or the like on the high pressure area 36 side can be positively distributed to the low pressure area 26.

Thus, even in the second embodiment configured as described above, substantially the same actions and effects as those in the first embodiment described above can be obtained. In particular, according to the second embodiment, the top plate portion 34 forming the diffuser 31 has a collision plate 34A extending in the horizontal direction at a position where the exhaust gas discharged from the connecting pipe 16 collides. As a result, when the exhaust gas is discharged from the connecting pipe 16, the exhaust gas can collide with the collision plate 34A to increase the pressure in the high pressure area 36. As a result, the pressure difference between the high pressure area 36 and the low pressure area 26 becomes large, so that the exhaust gas or the like on the high pressure area 36 side can be positively distributed to the low pressure area 26.

Next, FIG. 7 shows a third embodiment of the present invention. The feature of the present embodiment is that the peripheral wall portion includes a flat plate-shaped second peripheral wall connected to one end of the first peripheral wall and a flat plate-shaped third peripheral wall connected to the other end of the first peripheral wall. The upper opening is surrounded by a first peripheral wall, a second peripheral wall, and a third peripheral wall in a U-shape. In the third embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 7, the peripheral wall portion 42 of the diffuser 41 according to the third embodiment is a flat plate-shaped second peripheral wall 42B connected to one end of the first peripheral wall 42A and the first peripheral wall 42A, and the first peripheral wall 42A. It has a flat third peripheral wall 42C connected to the other end. As a result, the upper opening 8D of the exterior cover 8 is surrounded in a U shape by the first peripheral wall 42A, the second peripheral wall 42B, and the third peripheral wall 42C. Further, the diffuser 41 has a top plate portion 43 and an exhaust port 44.

Thus, even in the third embodiment configured in this way, substantially the same actions and effects as those in the first embodiment described above can be obtained. In particular, according to the third embodiment, the configuration of the diffuser 41 can be simplified.

In the first embodiment, the diffuser 17 is formed by a flange portion 18, a peripheral wall portion 21, a top plate portion 22, and an exhaust port 23, and is attached to the upper surface portion 8C of the exterior cover 8 via the flange portion 18. Is illustrated. However, the present invention is not limited to this, and for example, the peripheral wall portion of the diffuser may be directly fixed to the upper surface portion of the exterior cover. This configuration can be applied to other embodiments as well.

In the first embodiment, the peripheral wall portion 21 of the diffuser 17 is illustrated as a case where the peripheral wall portion 21 is formed as a rectangular tubular body by the first peripheral wall 21A, the second peripheral wall 21B, the third peripheral wall 21C, and the fourth peripheral wall 21D. .. However, the present invention is not limited to this, and for example, the peripheral wall portion of the diffuser may be formed as a pentagonal or larger cylinder. This configuration can be applied to other embodiments as well.

In each embodiment, a crawler type hydraulic excavator 1 has been described as an example of a construction machine. However, the present invention is not limited to this, and may be applied to, for example, a hydraulic excavator provided with a wheel-type lower traveling body. Further, it can be widely applied to other construction machines equipped with an engine such as a hydraulic crane.

1 Hydraulic excavator (construction machinery)
8 Exterior cover 8C Top surface 8D Top opening 9 Machine room 10 Engine 10A Exhaust pipe 14 Exhaust gas aftertreatment device 15 Tail pipe 16 Connection pipe 17, 31, 41 Diffuser 18 Flange part 21, 33, 42 Peripheral wall part 21A, 42A 1st Peripheral wall 21B, 42B 2nd peripheral wall 21C, 42C 3rd peripheral wall 21D 4th peripheral wall 22,34,43 Top plate 23,35,44 Exhaust port 34A Collision plate

Claims (4)

The engine placed in the machine room covered by the exterior cover,
An exhaust gas aftertreatment device that is connected to the exhaust pipe of the engine and treats the exhaust gas discharged from the engine.
A tail pipe that protrudes from the exhaust gas aftertreatment device toward the upper surface of the exterior cover and ejects the treated exhaust gas.
In a construction machine comprising a connecting pipe that is inserted through an upper opening formed in the upper surface portion of the exterior cover, extends downward from the upper surface portion of the exterior cover, and has a tail pipe inserted therein.
A diffuser is provided on the upper surface portion of the exterior cover.
The diffuser is ejected from the tail tube via the peripheral wall portion rising from a position surrounding the periphery of the upper opening, a top plate portion connected to the peripheral wall portion and covering the upper part of the connecting pipe, and the connecting pipe. It has a peripheral wall portion and an exhaust port for discharging exhaust gas guided by the top plate portion.
The first peripheral wall, which is a part of the peripheral wall portion and is located on the side opposite to the exhaust port across the upper opening, is formed as a flat plate.
The top plate portion is a construction machine characterized in that it is a flat plate extending diagonally upward from the first peripheral wall. In the construction machine according to claim 1,
The diffuser has a flange portion attached to the upper surface portion of the exterior cover.
The peripheral wall portion is a construction machine characterized in that it rises from the flange portion. In the construction machine according to claim 1,
A construction machine characterized in that the top plate portion of the diffuser has a collision plate extending in the horizontal direction at a position where exhaust gas discharged from the exhaust port collides. In the construction machine according to claim 1,
The peripheral wall portion has a flat plate-shaped second peripheral wall connected to one end of the first peripheral wall and a flat plate-shaped third peripheral wall connected to the other end of the first peripheral wall.
A construction machine characterized in that the upper opening is surrounded in a U shape by the first peripheral wall, the second peripheral wall, and the third peripheral wall.

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