Work machine

Abstract

To provide a work machine capable of minimizing risk of failure of electrical components associated with a post-treatment device.SOLUTION: A wheel loader 1 comprises: a post-treatment device 312 for purifying exhaust gas discharged from an engine 311; and a ventilation portion 4 provided on an engine hood 131 for discharging air inside an engine chamber 31 to the outside, wherein the ventilation portion 4 includes: an opening 40; a bracket 41 erected around the opening 40; and an opening cover 42 covering the opening 40 from above. An electrical component arrangement area α in which NOx sensors 61, 62 associated with the post-treatment device 312 are arranged is provided on a center side in a vehicle width direction or a front side than the opening 40 in an outer circumferential region of the opening 40 with its upper part covered by the opening cover 42 and surrounded by the bracket 41, on an upper surface of the engine hood 131.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a work machine equipped with an aftertreatment device for purifying exhaust gas discharged from an engine. [Background technology]

[0002] In a work machine, an aftertreatment device that removes nitrogen oxides (NOx) contained in the exhaust gas from the engine is generally housed in the engine compartment together with the engine. This aftertreatment device is prone to becoming hot due to the exhaust heat from the engine, and there are conventionally known technologies for dissipating the heat generated by the aftertreatment device and technologies for minimizing the effects of the heat generated by the aftertreatment device.

[0003] For example, the work machine described in Patent Document 1 has a top plate that covers the engine compartment above the engine, and an exhaust duct that is provided on the top plate and exhausts the air in the engine compartment to the outside of the engine compartment, and a part of the reducing agent supply pipe that leads the reducing agent to the reducing agent injection device is disposed in the exhaust duct above the reducing agent injection device. This prevents deterioration of the quality of the reducing agent by suppressing a temperature rise of the reducing agent in the reducing agent supply pipe.

[0004] In addition, the exhaust duct is provided outside the engine compartment, and has a rectangular cover support frame erected around the opening formed in the ceiling panel, and a truncated pyramid-shaped opening cover fixed to the cover support frame, thereby preventing rainwater, dust, etc. from entering the interior. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-180214 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the configuration described in Patent Document 1, only a portion of the reducing agent supply piping is arranged inside the exhaust duct, so there is a risk that other components associated with the aftertreatment device, particularly electrical components that are sensitive to heat such as temperature sensors and NOx sensors, will fail due to the heat generated by the aftertreatment device.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a work machine capable of reducing the risk of failure of electrical components associated with the post-treatment device. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a working machine comprising an engine, an aftertreatment device for purifying exhaust gas discharged from the engine, electrical equipment associated with the aftertreatment device, a building defining an engine compartment in which the engine and the aftertreatment device are housed and having a top plate covering the engine compartment from above, and a ventilation section provided on the top plate for discharging air within the engine compartment to the outside of the engine compartment, the ventilation section including an opening formed in the top plate, a frame-shaped bracket standing around the opening, and an opening cover covering the opening from above and attached to the bracket with a gap from an upper surface of the top plate, the working machine being characterized in that an electrical equipment arrangement area in which the electrical equipment is arranged is provided on the upper surface of the top plate, in the outer peripheral region of the opening, which is covered from above by the opening cover and surrounded by the bracket, forward of the opening or centrally in the vehicle width direction. Effect of the Invention

[0009] According to the present invention, it is possible to reduce the risk of failure of electrical components associated with the aftertreatment device. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0010] [Figure 1] 1 is an external side view showing one configuration example of a wheel loader according to an embodiment of the present invention. FIG. [Diagram 2]FIG. 2 is an exploded perspective view showing one configuration example of the upper part of the building. [Diagram 3] This is a plan view of the building from above with the ventilation opening cover removed. [Figure 4] 4 is a partially enlarged view of FIG. 3, showing an enlarged view of the ventilation section with the opening cover removed. FIG. [Diagram 5] 5 is a view of the ventilation part with the opening cover removed, as viewed from the direction of the arrow X in FIG. 4. [Figure 6] 5 is a view of the ventilation section with the opening cover removed, as viewed from the direction of the arrow Y in FIG. 4. [Figure 7] 5 is an external view of the ventilation part as seen from the direction of the arrow X in FIG. 4. [Figure 8] 5 is an external view of the ventilation part as seen from the direction of the arrow Y in FIG. 4. [Figure 9] 6 is a diagram showing another example of the positional relationship between the first NOx sensor and the second NOx sensor. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a wheel loader, which is a wheel-type work machine, will be described as an example of one aspect of a work machine according to an embodiment of the present invention.

[0012] <Overall configuration of wheel loader 1> First, the overall configuration of a wheel loader 1 will be described with reference to FIG.

[0013] FIG. 1 is an external side view showing an example of the configuration of a wheel loader 1 according to an embodiment of the present invention.

[0014] The wheel loader 1 is an articulated work vehicle whose body (machine body) is steered by bending near the center, and a front frame 1A forming the front part of the body and a rear frame 1B forming the rear part of the body are connected so as to be rotatable in the left-right direction (vehicle width direction) by a center joint 10, and the front frame 1A bends in the left-right direction relative to the rear frame 1B. In the following explanation, of the left-right direction of the body, the left direction in the forward direction is referred to as the "left direction", and the right direction in the forward direction is referred to as the "right direction".

[0015] The vehicle body is provided with four wheels 11, two of which are front wheels 11A provided on both the left and right sides of the front frame 1A, and the remaining two wheels 11 are rear wheels 11B provided on both the left and right sides of the rear frame 1B. Of the four wheels 11, only the front wheel 11A and rear wheel 11B provided on the left side are shown in FIG.

[0016] A hydraulically driven working device 2 is attached to the front of the front frame 1A for carrying out loading and unloading work such as digging up work objects such as soil and minerals and loading them into a loading destination such as a dump truck or a hopper.

[0017] The working device 2 has a lift arm 21 attached to the front frame 1A so as to be rotatable in the vertical direction, two lift arm cylinders (not shown) that drive the lift arm 21, a bucket 22 attached to the tip of the lift arm 21 so as to be rotatable in the vertical direction, a bucket cylinder 22A that drives the bucket 22, and a bell crank 23 that is rotatably connected to the lift arm 21 and forms a link mechanism between the bucket 22 and the bucket cylinder 22A.

[0018] The lift arm 21 rotates upward relative to the front frame 1A when the rods of the two lift arm cylinders extend, and rotates downward relative to the front frame 1A when the rods of the two lift arm cylinders contract.

[0019] The bucket 22 rotates upward and tilts backward relative to the lift arm 21 as the rod of the bucket cylinder 22A extends (tilt operation), and rotates downward and tilts forward relative to the lift arm 21 as the rod of the bucket cylinder 22A contracts (dump operation). This allows the bucket 22 to scoop up and discharge (dig and dump) work objects such as soil and minerals.

[0020] The bucket 22 can be replaced with various attachments, such as a blade, and the wheel loader 1 can perform various tasks such as snow removal and earth-pulling in addition to loading and unloading operations using the bucket 22.

[0021] The rear frame 1B is provided with a cab 12 in which an operator sits, a building 13 that defines an accommodation room that houses various devices required for driving the wheel loader 1, and a counterweight 14 for maintaining balance with the work implement 2 so that the vehicle body does not tilt. In the rear frame 1B, the cab 12 is disposed at the front, the counterweight 14 at the rear, and the building 13 between the cab 12 and the counterweight 14. That is, the cab 12 is provided on the front side of the building 13.

[0022] The accommodation chamber formed in the internal space of the building 13 is divided by a partition wall 130 into an engine room 31 on the front side and a cooler room 32 on the rear side.

[0023] The engine compartment 31 accommodates an engine 311, an aftertreatment device 312 for purifying the exhaust gas discharged from the engine 311, various devices associated with the engine 311 and the aftertreatment device 312, and various pipes such as connecting pipes that connect the engine 311 and the aftertreatment device 312.

[0024] The aftertreatment device 312 is disposed above the engine 311 in the engine compartment 31 and includes an oxidation catalyst device (DOC; Diesel Oxidation Catalyst) that oxidizes and removes nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and the like contained in the exhaust gas, a reducing agent injection device (DRT; Decomposition Reactor Tube) that injects a reducing agent (e.g., urea water) into the exhaust gas, and a selective catalytic reduction device (SCR; Selective Catalytic Reduction) that reduces and purifies nitrogen oxides (NOx) contained in the exhaust gas.

[0025] The engine compartment 31 is covered from above by an engine hood 131 that constitutes part of the top plate of the building 13. A ventilation section 4 that discharges air from within the engine compartment 31 to the outside of the engine compartment 31 is provided on the engine hood 131. In addition, a tail pipe 5 that discharges exhaust gas purified through the aftertreatment device 312 to the outside protrudes from the engine hood 131 toward the rear of the vehicle body. In addition, the upper end of the cab 12 is higher than the engine hood 131. As a result, the area of ​​the engine hood 131 on the cab 12 side (front side) is in the shadow of the cab 12.

[0026] The cooler chamber 32 houses a heat exchanger unit 321 composed of multiple heat exchangers such as a radiator that cools the cooling water of the engine 311, an oil cooler that cools the hydraulic oil, and an intercooler that cools the air pressurized by the turbocharger of the engine 311, as well as a cooling fan 322 that generates cooling air to cool the heat exchanger unit 321.

[0027] In FIG. 1, the partition wall 130, the engine 311, the aftertreatment device 312, the heat exchanger unit 321, and the cooling fan 322, which are arranged in the accommodation chamber, are each indicated by dashed lines.

[0028] <Configuration of ventilation section 4> Next, the configuration of the ventilation section 4 will be described with reference to FIGS.

[0029] FIG. 2 is an exploded perspective view showing one configuration example of the upper part of the building 13. FIG. 3 is a plan view of the building 13 from above with the opening cover 42 of the ventilation section 4 removed. FIG. 4 is a partially enlarged view of FIG. 3, showing the ventilation section 4 with the opening cover 42 removed in an enlarged manner. FIG. 5 is a view of the ventilation section 4 with the opening cover 42 removed, as seen from the direction of the arrow X in FIG. 4. FIG. 6 is a view of the ventilation section 4 with the opening cover 42 removed, as seen from the direction of the arrow Y in FIG. 4. FIG. 7 is an external view of the ventilation section 4 as seen from the direction of the arrow X in FIG. 4. FIG. 8 is an external view of the ventilation section 4 as seen from the direction of the arrow Y in FIG. 4.

[0030] As shown in Figures 2 to 4, 7, and 8, the ventilation section 4 includes an opening 40 that penetrates the engine hood 131 to connect the inside and outside of the engine compartment 31, a frame-shaped bracket 41 that stands around the opening 40, and an opening cover 42 that covers the opening 40 from above the bracket 41.

[0031] The opening 40 is an air vent for discharging a portion of the air in the engine compartment 31, particularly the air around the aftertreatment device 312, to the outside of the engine compartment 31. In this embodiment, the opening 40 is formed in a rectangular shape having long sides in the front-rear direction of the building 13 and short sides in the left-right direction of the building 13, as shown in Figs. 3 and 4 .

[0032] Moreover, the opening 40 is formed above the aftertreatment device 312 in the engine hood 131 and in front of the tail pipe 5. Here, the aftertreatment device 312 is disposed to the right of the center position C (indicated by a dashed line in FIG. 3) in the left-right direction of the building 13 within the engine compartment 31, and therefore the opening 40 is also formed to the right of the center position C. As a result, the ventilation section 4 including the opening 40 is also disposed toward the right side of the building 13. Therefore, the left side of the ventilation section 4 is located closer to the center of the building 13.

[0033] In Figures 3 and 4, the left edge of the opening 40 is located to the right of the center position C, but this is not limited to this, and depending on the shape and size, the left edge may be located beyond the center position C to the left.

[0034] The bracket 41 is formed, for example, by bending a metal plate. In this embodiment, the bracket 41 has a rectangular frame shape larger than the opening 40, and has four walls 41A to D arranged in the front-rear and left-right directions of the building 13, as shown in Fig. 3 and Fig. 4.

[0035] The front wall 41A stands at a predetermined distance W1 (shown in FIG. 4) from the front edge of the opening 40, and extends to the left of the left edge of the opening 40 and the center position C in the left-right direction of the building 13. The rear wall 41B stands along the rear edge of the opening 40, and like the front wall 41A, extends to the left of the left edge of the opening 40 and the center position C in the left-right direction of the building 13.

[0036] The left wall 41C stands at a predetermined distance W2 (shown in FIG. 4) from the left edge of the opening 40 and extends forward beyond the front edge of the opening 40. The right wall 41D stands along the right edge of the opening 40 and, like the left wall 41C, extends forward beyond the front edge of the opening 40.

[0037] That is, in this embodiment, the bracket 41 is positioned so that its right rear corner, which is the connection between the rear wall 41B and the right wall 41D, matches the position of the right rear corner of the opening 40, and is fixed to the upper surface 131A of the engine hood 131.

[0038] 2, 7, and 8, the opening cover 42 is a roof of the ventilation section 4 and has a rectangular base 421 arranged above the opening 40, and an extension 422 extending from the outer peripheral end of the base 421 toward the upper surface 131A of the engine hood 131 outside the bracket 41. The opening cover 42 is detachably attached to the bracket 41 by using bolts, for example, with a gap between the opening cover 42 and the upper surface 131A of the engine hood 131.

[0039] The base 421 is a mounting portion that is mounted on the bracket 41, and in this embodiment, has a rectangular shape that corresponds to the shape of the bracket 41. As shown in Fig. 2, the four corners of the base 421 are each formed with a bolt hole 421A that penetrates in the thickness direction (the vertical direction of the building 13).

[0040] The extending portion 422 is formed as an inclined surface that is inclined obliquely downward from the outer circumferential end of the base portion 421 toward the upper surface 131A of the engine hood 131, that is, formed with a downward gradient. Note that the extending portion 422 does not necessarily have to be an inclined surface, and may be formed as a vertical surface along each of the walls 41A-D of the bracket 41.

[0041] Also, as described above, a gap is present between the opening cover 42 and the upper surface 131A of the engine hood 131, and the lower end of the extension portion 422 is not in contact with the upper surface 131A of the engine hood 131 (non-contact state).

[0042] Between the opening cover 42 and the bracket 41, a vent hole S is provided to ensure ventilation in the ventilation section 4. This vent hole S is formed by cutting out a part of the metal plate forming the bracket 41. That is, the bracket 41 has a high wall portion 411 having a height from the upper surface 131A of the engine hood 131 to the base portion 421 of the opening cover 42, and a low wall portion 412 that is cut out and has a predetermined height lower than the high wall portion 411. Therefore, the vent hole S corresponds to a gap formed between the low wall portion 412 and the opening cover 42.

[0043] Bolt mounting pieces 413 extend inward from the upper end of the high wall portion 411, corresponding to each bolt hole 421A formed in the base portion 421 of the opening cover 42. Each bolt mounting piece 413 is a plate piece facing the base portion 421 of the opening cover 42, and a nut is fixed to the back side (the side facing the upper surface 131A of the engine hood 131) as shown in Fig. 5.

[0044] In this embodiment, the front wall 41A and the rear wall 41B are each composed of only a low wall portion 412. The left wall 41C and the right wall 41D are each composed of three low wall portions 412 and two high wall portions 411 arranged between adjacent low wall portions 412. That is, the opening cover 42 is attached to the left wall 41C and the right wall 41D of the bracket 41.

[0045] 7 and 8, it is desirable that the tip portion of the extension portion 422 of the opening cover 42 overlaps with the bottom wall portion 412 in the up-down direction, that is, the lower end portion of the extension portion 422 is located lower (on the upper surface 131A side of the engine hood 131) than the upper end portion of the bottom wall portion 412. This prevents the ventilation hole S from being exposed to the outside, making it difficult for water, dust, and the like to enter the ventilation portion 4 from the outside.

[0046] An electrical equipment arrangement area α is provided on the upper surface 131A of the engine hood 131 in front of and toward the center in the left-right direction of the opening 40 in the outer peripheral area of ​​the opening 40, which is covered from above by the opening cover 42 and surrounded by the bracket 41. In this embodiment, a pair of NOx sensors 61, 62 that detect the concentration of nitrogen oxides (NOx) contained in the exhaust gas discharged from the engine 311 are arranged in the electrical equipment arrangement area α.

[0047] In general, the NOx sensor is configured as a pair of a probe inserted into the exhaust gas and a module having a function of calculating the NOx concentration contained in the exhaust gas. Therefore, the probe needs to be attached to the aftertreatment device 312, and the "pair of NOx sensors 61, 62" here refers to the NOx sensor module.

[0048] In this embodiment, the electrical equipment arrangement area α is an area on the engine hood 131 formed between the front edge and left edge of the opening 40 and the front wall 41A and left wall 41C of the bracket 41. Therefore, the distance W1 between the front edge of the opening 40 and the front wall 41A of the bracket 41 and the distance W2 between the left edge of the opening 40 and the left wall 41C of the bracket 41 may each be set to a distance at least at which the NOx sensors 61, 62 can be mounted (a distance corresponding to the short-side dimension of the module of each NOx sensor 61, 62 in Figs. 3 and 4).

[0049] The pair of NOx sensors 61, 62 are one form of electrical equipment associated with the after-treatment device 312, and the first NOx sensor 61 detects the NOx concentration on the inlet side of the after-treatment device 312, while the other, the second NOx sensor 62, detects the NOx concentration on the outlet side of the after-treatment device 312.

[0050] 5, the top surface (front surface) of each of the NOx sensors 61, 62 is located below each of the bolt mounting pieces 413, and the maximum dimension in the height direction is smaller than the height of the high wall portion 411. In other words, the high wall portion 411 is formed higher than the maximum dimension in the height direction of each of the NOx sensors 61, 62.

[0051] Electrical components such as the pair of NOx sensors 61, 62 are vulnerable to heat and therefore have a risk of failure due to heat generated from the aftertreatment device 312. By providing the pair of NOx sensors 61, 62 in the ventilation section 4 provided on the upper surface 131A of the engine hood 131 in this manner, the risk of failure due to heat can be reduced.

[0052] Furthermore, in this embodiment, since the ventilation section 4 is provided with an air vent S, the ventilation section 4 has better air permeability and excellent heat dissipation properties compared to when the ventilation hole S is not provided (when all four walls 41A-D of the bracket 41 are composed only of the high wall portion 411), and it is possible to reduce the risk of failure of the pair of NOx sensors 61, 62 due to heat.

[0053] In addition, since the opening cover 42 covers the upper part of the ventilation part 4, it is possible to reduce the risk that water such as rainwater dripping from above will enter the inside and cause a malfunction of the pair of NOx sensors 61, 62. On the other hand, when water is sprayed from the underside of the vehicle body during a car wash, water may enter the ventilation part 4 through the gap between the bracket 41 and the opening cover 42.

[0054] Here, if the areas of the engine hood 131 are divided according to the high and low risk of water intrusion due to water being sprayed from the underside of the vehicle body, the area toward the center and front (driver's cab 12 side) of the building 13 in the left-right direction (the area shown by the dotted line in Figure 4) is the low area β1, which has the lowest risk of water intrusion due to water spraying, the area behind the low area β1, i.e., the area toward the center of the building 13 in the left-right direction excluding the front and rear end areas (the area shown by the dotted line in Figure 4), is the medium area β2, which has a medium risk of water intrusion due to water spraying, and the remaining areas other than the low area β1 and the medium area β2 are the high area β3, which has a high risk of water intrusion due to water spraying.

[0055] During a car wash, water is sprayed from the left and right sides and from the lower rear (counterweight 14 side) of the building 13, so the left and right end regions and rear end region of the engine hood 131 (i.e., high region β3) are most likely to be splashed with water. On the other hand, the central region including the center position C of the engine hood 131 is less likely to be splashed with water than the left and right end regions and rear end region. Furthermore, since the central and front region of the engine hood 131 (i.e., low region β1) is located directly behind the cab 12, the cab 12 acts as a shield against the sprayed water, making it less likely to be splashed with water.

[0056] The electrical equipment arrangement region α in which the pair of NOx sensors 61, 62 are arranged is an area consisting of a low region β1 and a medium region β2, as shown in Fig. 4. Therefore, the pair of NOx sensors 61, 62 are unlikely to be directly splashed with water even during a car wash, and the risk of failure due to water discharge can be reduced.

[0057] In this embodiment, the first NOx sensor 61 is disposed in a region formed between the front edge of the opening 40 within the electrical equipment arrangement area α and the front wall 41A of the bracket 41, i.e., the low region β1, and the second NOx sensor 62 is disposed in a region formed between the left edge of the opening 40 within the electrical equipment arrangement area α and the left wall 41C of the bracket 41, i.e., the middle region β2.

[0058] In consideration of the risk of water entering the ventilation section 4 due to water discharge, it is preferable that the bracket 41 does not have the low wall section 412, i.e., does not have the ventilation hole S. However, since a pair of NOx sensors 61, 62 that are vulnerable to heat are disposed inside the ventilation section 4, if the bracket 41 is composed of only the high wall section 411 and does not have the low wall section 412, i.e., if the ventilation hole S is not formed, the ventilation inside the ventilation section 4 will be insufficient, and the pair of NOx sensors 61, 62 may break down due to heat.

[0059] As described above, the front wall 41A erected along the longitudinal direction of the first NOx sensor 61 is composed only of the low wall portion 412. Therefore, it may seem that water discharged from the water source will directly splash onto the first NOx sensor 61 through the ventilation hole S, but as shown in Fig. 4, the position where the front wall 41A is erected is the low region β1, so that the risk of water entering the ventilation portion 4 from the discharged water is low.

[0060] In addition, the left wall 41C that stands along the longitudinal direction of the second NOx sensor 62 also includes a low wall portion 412. However, as shown in FIG. 4, since it stands across both the low region β1 and the middle region β2, the risk of water entering the ventilation portion 4 due to the discharge of water is low.

[0061] However, since the second NOx sensor 62 is disposed in the middle region β2 rather than the low region β1, the high wall portion 411 is disposed at a position on the left wall 41C corresponding to the location of the second NOx sensor 62. In other words, the second NOx sensor 62 is disposed in a portion of the electrical component arrangement region α adjacent to the high wall portion 411. Hereinafter, the high wall portion 411 adjacent to the second NOx sensor 62 is referred to as the "corresponding high wall portion 411A."

[0062] Unlike the other high wall portions 411, the corresponding high wall portion 411A is disposed over an area corresponding to the range longitudinally overlapping with the second NOx sensor 62. The other high wall portions 411 are disposed in an area on the left wall 41C or the right wall 41D that is adapted to the size of the bolt mounting piece 413 and is narrower than the area where the corresponding high wall portion 411A is disposed.

[0063] Here, "the area corresponding to the range overlapping longitudinally with the second NOx sensor 62" does not necessarily mean that the arrangement area of ​​the corresponding high wall portion 411A in the left wall 41C is the range that completely overlaps longitudinally with the second NOx sensor 62 (i.e., the entire second NOx sensor 62 is hidden by the corresponding high wall portion 411A), and it is acceptable for a portion of the second NOx sensor 62 to be somewhat exposed from the corresponding high wall portion 411A.

[0064] In the left wall 41C, low wall portions 412 are arranged on both sides of the corresponding high wall portion 411A, thereby ensuring ventilation within the ventilation section 4, while the corresponding high wall portion 411A is arranged so as to prevent the second NOx sensor 62 located in the middle region β2 from being directly splashed with water from the water discharge.

[0065] As described above, the high wall portion 411 (including the corresponding high wall portion 411A) is higher than the maximum dimension in the height direction of the second NOx sensor 62 (electrical component), and in this embodiment, since the bolt mounting piece 413 is provided, the high wall portion 411 has a height ranging from the upper surface 131A of the engine hood 131 to the base portion 421 of the opening cover 42. The low wall portion 412 in this embodiment is configured to form the ventilation hole S for ensuring ventilation within the ventilation section 4, and is lower than the high wall portion 411 by the size of the ventilation hole S (a predetermined height).

[0066] As described above, because the bracket 41 has the high wall portion 411 and the low wall portion 412, it is possible to minimize both the risk of failure due to heat and the risk of failure due to water (including water dripping from above the ventilation section 4 and water entering between the bracket 41 and the opening cover 42) for the pair of NOx sensors 61, 62 arranged in the electrical equipment arrangement area α in the ventilation section 4.

[0067] In addition, in this embodiment, the electrical equipment placement area α in which the pair of NOx sensors 61, 62 are arranged is composed of a low area β1 and a medium area β2, so that the risk of failure of the pair of NOx sensors 61, 62 due to water discharge can be further reduced.

[0068] In addition, the electrical equipment arrangement area α does not necessarily have to be composed of a low area β1 and a middle area β2, but may be composed of only the low area β1 or only the middle area β2, or is not limited to these, and may be at least an area on the upper surface 131A of the engine hood 131, which is in front of the opening 40 or is at the center in the vehicle width direction in the outer periphery of the opening 40 covered from above by the opening cover 42 and surrounded by the bracket 41.

[0069] Furthermore, in this embodiment, the bottom wall portion 412 is provided at a position on the engine hood 131 at the center and front side in the left-right direction of the building 13, i.e., in the low region β1. Therefore, while ensuring ventilation within the ventilation section 4, it is possible to better prevent water from being directly sprayed on the pair of NOx sensors 61, 62 arranged in the electrical equipment arrangement area α.

[0070] <Modification> Next, a modified example relating to the positional relationship between the pair of NOx sensors 61, 62 will be described with reference to FIG.

[0071] FIG. 9 is a diagram showing another example of the positional relationship between the first NOx sensor 61 and the second NOx sensor 62. In FIG.

[0072] In the above embodiment, the first NOx sensor 61 was arranged in the low region β1 and the second NOx sensor 62 was arranged in the middle region β2, but in this modified example, both the first NOx sensor 61 and the second NOx sensor 62 are arranged in the low region β1.

[0073] 9, the first NOx sensor 61 is disposed in a region of the electrical equipment arrangement area α that is formed between the front edge of the opening 40 and the front wall 41A of the bracket 41, similarly to the embodiment. On the other hand, the second NOx sensor 62 is disposed in a region of the electrical equipment arrangement area α that is formed between a left front corner of the opening 40 and a left front corner of the bracket 41 (the connection between the front wall 41A and the left wall 41C), unlike the embodiment.

[0074] Further, the second NOx sensor 62 is disposed so that its longitudinal direction is aligned with the short-side direction of the first NOx sensor 61. In other words, the first NOx sensor 61 and the second NOx sensor 62 are disposed so that their longitudinal directions intersect (are perpendicular to each other).

[0075] In this way, since both of the pair of NOx sensors 61, 62 are arranged in the low region β1, the risk of failure of the pair of NOx sensors 61, 62 due to water discharge can be reduced more than that of the pair of NOx sensors 61, 62 in the embodiment.

[0076] In this modified example, since the second NOx sensor 62 is arranged in the low region β1, the left wall 41C does not have a corresponding high wall portion 411A, but only has a high wall portion 411 arranged in an area corresponding to the size of the bolt mounting piece 413.

[0077] The embodiments of the present invention have been described above. Note that the present invention is not limited to the above-described embodiments, and includes various other modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of the above-described embodiments with the configuration of other embodiments, and it is also possible to add the configuration of other embodiments to the configuration of the above-described embodiments. Furthermore, it is possible to add, delete, or replace a part of the configuration of the above-described embodiments with another configuration.

[0078] For example, in the above embodiment, the wheel loader 1 is taken as an example of one type of work machine, but the present invention is not limited to this, and may be other work machines such as a hydraulic excavator.

[0079] In addition, in the above embodiment, a pair of NOx sensors 61, 62 was given as an example of one form of electrical equipment associated with the aftertreatment device 312, but this is not limited to this, and any electrical equipment associated with the aftertreatment device 312, such as a temperature sensor, may be used. [Explanation of symbols]

[0080] 1: Wheel loader (work machine) 4: Ventilation section 13: Building 31: Engine room 40: Opening 41: Bracket 42: Opening cover 61, 62: NOx sensor (electrical equipment) 131: Engine hood (top plate) 311: Engine 312: Post-processing device 411:High wall part 411A: Corresponding high wall section (high wall section) 412: Low wall 421: Base 422: Extension part α: Electrical component placement area

Claims

1. The engine, an aftertreatment device for purifying exhaust gas discharged from the engine; Electrical equipment associated with the post-treatment device; a building that defines an engine compartment in which the engine and the aftertreatment device are housed, the building having a top plate that covers the engine compartment from above, and a ventilation section that is provided on the top plate and that exhausts air within the engine compartment to the outside of the engine compartment, The ventilation portion is An opening formed in the top plate; A frame-shaped bracket standing around the opening; an opening cover that covers the opening from above and is attached to the bracket with a gap between the opening cover and the upper surface of the top plate. In the work machine, An electrical equipment arrangement area in which the electrical equipment is arranged is provided on the upper surface of the top plate in a peripheral area of ​​the opening, the peripheral area being covered from above by the opening cover and surrounded by the bracket, on the front side of the opening or on the center side in a vehicle width direction. A working machine characterized by:

2. 2. The work machine according to claim 1, The bracket is A wall portion is provided on the upper surface of the top plate, The electrical equipment arrangement area includes: formed between the wall and the opening A working machine characterized by:

3. 3. The work machine according to claim 2, The wall portion is a high wall portion formed higher than a maximum dimension of the electrical equipment in a height direction, The electrical equipment includes: The electrical equipment is disposed in a portion of the electrical equipment arrangement area adjacent to the high wall portion. A work machine characterized by:

4. 4. The work machine according to claim 3, The wall portion is A low wall portion formed at a predetermined height lower than the high wall portion. A working machine characterized by:

5. 5. The working machine according to claim 4, An operator's cab is provided at the front of the building, The upper end of the cab is higher than the top plate of the building, The bottom wall portion is The cooling fan is provided at a position on the left-right center side of the building and on the side of the driver's cab. A working machine characterized by:

6. 5. The working machine according to claim 4, The opening cover is A base disposed above the opening; an extension portion formed with a downward slope from an outer peripheral end of the base portion toward the upper surface of the top plate and extending outside the bracket; The tip portion of the extension portion is Located below the upper end portion of the bottom wall A working machine characterized by:

7. 2. The work machine according to claim 1, The electrical equipment includes: A NOx sensor that detects the concentration of nitrogen oxides contained in the exhaust gas. A working machine characterized by:

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