Transportation vehicle

Abstract

To maintain good left and right weight balance in a transportation vehicle equipped with a reducing agent tank.SOLUTION: A transportation vehicle having a vehicle body, an engine, a fuel tank, and a hydraulic oil tank includes: an exhaust gas purifier (35); a first reducing agent tank (25 L) and a second reducing agent tank (25R) for storing reducing agents; and a controller (13). The hydraulic oil tank and the first reducing agent tank are provided on one of left and right sides of the vehicle body, and the fuel tank and the second reducing agent tank are provided on the other of the left and right sides of the vehicle body. The controller supplies either the reducing agent stored in the first reducing agent tank or the reducing agent stored in the second reducing agent tank to the exhaust gas purifier based on an amount of hydraulic oil stored in the hydraulic oil tank, the amount of the reducing agent stored in the first reducing agent tank, the amount of fuel stored in the fuel tank, and the amount of the reducing agent stored in the second reducing agent tank, which are detected by sensors (23, 26, 27).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a transport vehicle, and is particularly suitable for a large mining dump truck. [Background technology]

[0002] As background art in this technical field, for example, Patent Document 1 discloses a dump truck in which "a hydraulic oil tank is attached to one of the left and right sides of a main frame, a main fuel tank is attached to the other, an auxiliary fuel tank having a smaller volume than the main fuel tank is placed on top of the hydraulic oil tank, the auxiliary fuel tank and the main fuel tank are connected by a communicating pipe, and the main fuel tank and the auxiliary fuel tank are provided with breather vents for letting air in and out of each tank, and a suction pipe forming a fuel suction port in the main fuel tank, and further the main fuel tank and the auxiliary fuel tank are arranged so that their top surfaces are at approximately the same height" (see abstract).

[0003] According to this conventional technology, a large amount of fuel can be secured, and even when the fuel is consumed, the weight balance between the left and right sides of the vehicle body can be maintained in a good state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 080714 Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, diesel engines are used as engines for transport vehicles such as dump trucks. Since the exhaust gas of a diesel engine contains a large amount of nitrogen oxides (hereinafter referred to as NOx), etc., a NOx purification device (exhaust gas purification device) for purifying the NOx may be provided. The NOx purification device is, for example, provided in the exhaust pipe of the engine and is composed of a urea selective reduction catalyst or the like for removing NOx in the exhaust gas. In addition, a reducing agent tank is provided in association with the NOx purification device, and urea water (urea aqueous solution) is stored in the reducing agent tank as a reducing agent.

[0006] For example, in many work sites such as mines, facilities for supplying urea water are not provided. Therefore, it is desirable to increase the capacity of the reducing agent tank so that the number of times urea water needs to be supplied is reduced. However, if the reducing agent tank is enlarged, there is a problem that the left and right weight balance of the vehicle on which the reducing agent tank is mounted is accordingly disrupted.

[0007] Incidentally, Patent Document 1 refers to the configuration of the fuel tank for maintaining the left and right weight balance, but makes no mention whatsoever of the reducing agent tank.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to maintain a good left-right weight balance in a transport vehicle equipped with a reducing agent tank. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the present invention is a transport vehicle including a vehicle body, an engine for driving the vehicle body, a fuel tank for storing fuel supplied to the engine, a driven body provided on the vehicle body, a hydraulic actuator for driving the driven body, and a hydraulic oil tank for storing hydraulic oil supplied to the hydraulic actuator, the transport vehicle including an exhaust gas purification device for purifying exhaust gas from the engine, a first reducing agent tank and a second reducing agent tank for storing reducing agent to be supplied to the exhaust gas purification device, and a storage amount of fuel in the fuel tank, a storage amount of hydraulic oil in the hydraulic oil tank, a storage amount of reducing agent in the first reducing agent tank, and a storage amount of reducing agent in the second reducing agent tank. the hydraulic oil tank and the first reducing agent tank are provided on one of the left and right sides of the vehicle body, and the fuel tank and the second reducing agent tank are provided on the other of the left and right sides of the vehicle body, and the controller supplies either the reducing agent stored in the first reducing agent tank or the reducing agent stored in the second reducing agent tank to the exhaust gas purification device based on the amount of hydraulic oil stored in the hydraulic oil tank, the amount of reducing agent stored in the first reducing agent tank, the amount of fuel stored in the fuel tank, and the amount of reducing agent stored in the second reducing agent tank, detected by the sensors. Effect of the Invention

[0010] According to the present invention, it is possible to maintain a good left-right weight balance in a transport vehicle equipped with a reducing agent tank. Note that problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a top view of a main part of a vehicle body of the dump truck according to the first embodiment. [Diagram 2] 1 is a bird's-eye view of a dump truck according to a first embodiment, as viewed from above. [Diagram 3] 1 is a top view of a main part of a vehicle body of a dump truck according to a first embodiment. [Figure 4] FIG. 2 is a diagram showing a structure of a urea water tank of the dump truck according to the first embodiment. [Diagram 5] 1 is a configuration diagram of a urea water supply system according to a first embodiment. FIG. [Figure 6] 4 is a flowchart of a urea water supply switching control according to the first embodiment. [Figure 7] 4 is a graph comparing the change in vehicle body weight difference between the first embodiment and the conventional technology. [Figure 8] FIG. 6 is a configuration diagram of a urea water supply system according to a second embodiment. [Figure 9] 10 is a flowchart of a urea water supply switching control according to a second embodiment. [Figure 10] FIG. 4 is a schematic diagram showing a structure of a urea water tank according to a first modified example. [Figure 11] FIG. 11 is a schematic diagram showing a structure of a urea water tank according to Modification 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) Hereinafter, an embodiment of a transport vehicle according to the present invention will be described using a dump truck as an example. Note that the dump truck shown below is a large, electrically driven dump truck used in work sites such as mines, but the present invention is not limited to large dump trucks for mining. The present invention can also be applied to transport vehicles other than dump trucks, such as wheel loaders.

[0013] Fig. 1 is a top view of a main part of a vehicle body of a dump truck according to a first embodiment of the present invention, Fig. 2 is a bird's-eye view of the dump truck according to the first embodiment from above, and Fig. 3 is a bird's-eye view of the main part of the vehicle body of the dump truck according to the first embodiment from above. For convenience of explanation, the loading platform 31 of the dump truck is omitted from Figs. 1 and 3.

[0014] As shown in Figures 1 to 3, the dump truck 100 comprises a body frame (body) 30, front wheels 5L, 5R and rear wheels 3L, 3R mounted on the body frame 30, an engine 1 for driving the body frame 30, a fuel tank 20 for storing fuel supplied to the engine 1, a loading platform (driven body) 31 mounted on the body frame 30, a pair of hoist cylinders (hydraulic actuators) 32 for driving the loading platform 31, and a hydraulic oil tank 19 for storing hydraulic oil supplied to the pair of hoist cylinders 32.

[0015] As shown in FIG. 1, the engine 1 is provided on a vehicle body frame 30. The engine 1 is mechanically connected to a generator 2. The engine 1 is also mechanically connected to a pump unit 7. When the engine 1 is driven, the pump unit 7 draws in hydraulic oil stored in a hydraulic oil tank 19 and discharges (supplies) it toward a pair of hoist cylinders 32. The rear wheels 3L, 3R are mechanically connected to the traveling motors 4L, 4R, and are driven by electric power generated by the generator 2. In other words, when the engine 1 is driven, the generator 2 generates electric power, and the traveling motors 4L, 4R are rotated and driven by the electric power, so that the dump truck 100 travels. Also, a first urea water tank (first reducing agent tank) 25L is provided on the side of the hydraulic oil tank 19, and a second urea water tank (second reducing agent tank) 25R is provided on the side of the fuel tank 20. That is, in this embodiment, the hydraulic oil tank 19 and the first urea water tank 25L are provided on the left side of the vehicle body frame 30, and the fuel tank 20 and the second urea water tank 25R are provided on the right side of the vehicle body frame 30.

[0016] Here, the first refill port 25L1 of the first urea water tank 25L is provided near the second urea water tank 25R via a refill pipe 25L2 (see FIG. 3). That is, in this embodiment, the first refill port 25L1 of the first urea water tank 25L and the second refill port 25R1 of the second urea water tank 25R are concentrated on the right side of the body frame 30. This allows the worker to refill both urea water tanks 25L, 25R with urea water without moving to another location when refilling the fuel tank 20.

[0017] Of course, the first supply port 25L1 of the first urea water tank 25L need not be extended to the right side of the vehicle body frame 30 via the supply pipeline 25L2, but supply ports 25L1, 25R1 may be provided on both the left and right sides of the vehicle body frame 30, respectively.

[0018] As shown in FIG. 2, the dump truck 100 is also equipped with a resistor 8 that converts the electricity generated by the generator 2 or the regenerative brake into heat and releases it into the atmosphere, a control unit 9 that performs various controls of the dump truck 100, an SCR muffler 10 that contains a NOx selective reduction catalyst device 35 (see FIG. 5), and a cab 11 in which an operator rides.

[0019] As shown in Fig. 3, the SCR muffler 10 is connected to an exhaust pipe 15 through which exhaust gas discharged from the engine 1 flows, and purifies the exhaust gas by injecting urea water (reducing agent) into the exhaust gas as it passes through the SCR muffler 10. The hydraulic oil tank 19 and the fuel tank 20 are fastened to the vehicle body frame 30 with bolts. The hydraulic oil tank 19 and the fuel tank 20 are equipped with level sensors 26, 27 for detecting the liquid levels in the tanks (see Fig. 5).

[0020] Here, the hydraulic oil does not decrease unless there is an oil leak from the hydraulic oil tank 19 or the hose because the hydraulic oil only circulates between the hydraulic oil tank 19 and the hoist cylinder 32. On the other hand, the fuel is consumed as long as the engine 1 is running. That is, the total weight of the fuel tank 20 (weight including fuel) changes while the dump truck 100 is traveling, but the total weight of the hydraulic oil tank 19 (weight including hydraulic oil) does not change. Therefore, the left-right balance of the vehicle weight changes while the dump truck 100 is traveling. Therefore, in order to suppress such a change in the weight balance, in this embodiment, control is performed to switch between the urea water tanks 25L and 25R to be used (described in detail later).

[0021] Next, the structures of the first urea water tank 25L and the second urea water tank 25R will be explained. However, since the structures of both are basically the same, the following will explain the first urea water tank 25L in detail and omit the explanation of the second urea water tank 25R.

[0022] 4 is a diagram showing the structure of the urea water tank of the dump truck according to the first embodiment. The first urea water tank 25L is equipped with a urea water sensor 23 for detecting the liquid level, concentration, and temperature of the urea water 24 therein. If the temperature of the urea water 24 falls below -11°C, the urea water 24 will freeze and will not be able to be supplied to the SCR muffler 10.

[0023] Therefore, the first urea water tank 25L has a heater function for heating the urea water 24 at low temperatures. Specifically, for the heater function, the engine 1 coolant is used as a heat medium, and heat is exchanged between the engine 1 coolant and the urea water 24 in the first urea water tank 25L via the engine coolant piping 16. That is, the urea water 24 is heated by the engine 1 coolant. In addition, in Fig. 4, reference symbol 16S denotes an engine coolant supply piping, and reference symbol 16R denotes an engine coolant return piping.

[0024] Furthermore, the first urea water tank 25L is provided with a urea water supply pipe 20S for sending the urea water 24 from the first urea water tank 25L to the SCR muffler 10, and a urea water return pipe 20R for returning the urea water 24 that is not injected by the SCR muffler 10 into the first urea water tank 25L.

[0025] As will be described in detail later, as shown in Fig. 5, a urea water pump 18L is provided in the urea water supply pipe 20S, and by driving the urea water pump 18L, the urea water 24 in the first urea water tank 25L passes through the urea water supply pipe 20S and is sent to the SCR muffler 10. The urea water 24 sent to the SCR muffler 10 is then injected from the urea water injector 22 into the exhaust gas 33, purifying the exhaust gas 33. The urea water 24 that is not injected is returned to the first urea water tank 25L through the urea water return pipe 20R. The same applies to the second urea water tank 25R (however, in Fig. 5, the urea water return pipe 20R to the second urea water tank 25R is not shown).

[0026] In addition, when used in a low-temperature environment, if the urea water supply pipe 20S and the urea water return pipe 20R are relatively long, there is a risk that the urea water 24 will freeze inside the pipes. Therefore, in order to prevent freezing, it is preferable to use a hose with a heater function incorporating an electric heating wire.

[0027] Next, a description will be given of a urea water supply system that is applied to the dump truck 100. Fig. 5 is a configuration diagram of the urea water supply system according to the first embodiment.

[0028] As shown in FIG. 5, the urea water supply system 40 includes a NOx selective catalytic reduction device (SCR Catalyst / exhaust gas purification device) 35 contained in the SCR muffler 10, a pair of urea water tanks 25L, 25R provided on the left and right, urea water pumps 18L, 18R, a urea water switching valve 21, a urea water injector 22, and a controller 13 provided in the cab 11.

[0029] The NOx selective catalytic reduction device 35 is a device equipped with a reduction catalyst that reduces and purifies nitrogen oxides (NOx) contained in the exhaust gas 33 discharged from the engine 1 by using the urea water 24.

[0030] The urea water injector 22 is disposed upstream of the NOx selective reduction catalyst device 35, and injects urea water into the exhaust gas 33. The urea water injector 22 is connected to urea water tanks 25L, 25R via a urea water supply pipe 20S.

[0031] The urea water pumps 18L, 18R are electrically operated pumps, and are driven by power supplied via the controller 13 when the engine 1 is started. When the urea water pumps 18L, 18R are driven, the urea water 24 in the urea water tanks 25L, 25R is pumped up and supplied to the urea water injector 22 via the urea water supply pipe 20S, where it is pressurized. A urea water switching valve 21 is provided between the urea water injector 22 and the urea water pumps 18L, 18R, and depending on the position of the urea water switching valve 21, the urea water 24 stored in the first urea water tank 25L or the second urea water tank 25R is selectively supplied to the urea water injector 22. The control of switching the position of the urea water switching valve 21 will be described later.

[0032] The urea water injector 22 injects urea water into the exhaust gas 33 flowing through the exhaust pipe 15 in response to a control signal from the controller 13. When the urea water is injected (supplied), ammonia is produced from the urea water by the NOx selective reduction catalyst device 35, and the NOx in the exhaust gas 33 is reduced by the ammonia, and is decomposed into water and nitrogen.

[0033] 5, the controller 13 acquires information on the liquid level detected by a level sensor 26 provided in the hydraulic oil tank 19 and a level sensor 27 provided in the fuel tank 20. The information on the liquid level is used to calculate the total weight of the hydraulic oil tank 19 and the total weight of the fuel tank 20.

[0034] In addition, an indoor heating unit 12 is provided in the cab 11. The indoor heating unit 12 heats the interior of the vehicle using engine cooling water as a heat medium. The engine cooling water delivered from the engine 1 passes through an engine cooling water branch valve 17 and is supplied to the indoor heating unit 12.

[0035] An engine control unit (ECU) 14 controls the opening and closing operation of the engine cooling water branch valve 17 to adjust the supply of engine cooling water to the first urea water tank 25L and the second urea water tank 25R. Specifically, the ECU 14 controls the opening and closing switching of the engine cooling water branch valve 17 based on the temperatures in the tanks detected by urea water sensors 23 provided in the urea water tanks 25L, 25R, respectively.

[0036] More specifically, the ECU 14 acquires a temperature value in the urea water tanks 25L, 25R detected by the urea water sensor 23. The ECU 14 compares the acquired temperature value with a urea heater start threshold temperature previously set in the ECU 14, and when the temperature value acquired from the urea water sensor 23 is lower than the urea heater start threshold temperature, the ECU 14 controls the engine cooling water branch valve 17 to open in order to supply engine cooling water to the urea water tanks 25L, 25R. On the other hand, when the temperature value acquired from the urea water sensor 23 is higher than the urea heater start threshold temperature, the ECU 14 controls the engine cooling water branch valve 17 to close so that the engine cooling water is not sent to the urea water tanks 25L, 25R.

[0037] Next, the control process of the urea water supply system will be described. Fig. 6 is a flowchart of the urea water supply switching control according to the first embodiment. When the engine 1 is started, the urea water supply switching control is initiated (process S1). Next, in process S2, the liquid level values ​​of the urea water tanks 25L, 25R detected by the urea water sensor 23 are sent to the controller 13 of the vehicle body via the ECU 14 provided in the engine 1. In addition, the controller 13 obtains information on the liquid levels of the respective tanks 19, 20 from the level sensors 26, 27 provided in the hydraulic oil tank 19 and the fuel tank 20, respectively.

[0038] Next, in process S3, the controller 13 calculates the liquid volume of each of the tanks 19, 20, 25L, 25R based on the information on each liquid level acquired in process S2, and then calculates the current total weight of each of the tanks 19, 20, 25L, 25R from the empty weights of the hydraulic oil tank 19, fuel tank 20, and urea water tanks 25L, 25R that are set (stored) in advance and the calculated liquid volumes of each of the tanks 19, 20, 25L, 25R.

[0039] The controller 13 is configured to calculate the total weight M of the tanks provided on the left side of the vehicle body, that is, the hydraulic oil tank 19 and the first urea water tank 25L. L is calculated as the first total value, and the total weight M R is calculated as the second total value.

[0040] Next, in step S4, the controller 13 calculates the total weight M L (First total value) and total weight M R Specifically, the controller 13 compares the total weight M R Total weight M L The total weight M is subtracted, and the difference (positive or negative) determines whether the left or right side of the vehicle is heavier. R Total weight M L If the value obtained by subtracting the above is positive (Yes in step S4), the controller 13 calculates the total weight M R The urea water switching valve 21 is switched to position A so that the urea water 24 is supplied from the second urea water tank 25R to the SCR muffler 10 (step S5). As a result of the urea water 24 stored in the second urea water tank 25R being consumed, the total weight M R gradually becomes lighter.

[0041] On the other hand, in process S4, M R From M L If the value obtained by subtracting the above is zero or negative, the controller 13 calculates the total weight ML The urea water switching valve 21 is switched to position B so that the urea water 24 is supplied from the first urea water tank 25L to the SCR muffler 10 (step S6). As a result of the urea water 24 stored in the first urea water tank 25L being consumed, the total weight M L gradually becomes lighter.

[0042] In step S4, M R From M L If the subtracted value is zero, the process may proceed to S5.

[0043] Next, the effect of this embodiment will be described with reference to Fig. 7. Fig. 7 is a graph showing a comparison of changes in the vehicle body weight difference between the first embodiment and the conventional technology. In Fig. 7, the vertical axis represents the weight difference M between the left and right sides of the vehicle body. R -M L The axis of gravity is (kg), and the horizontal axis is time t (seconds). Here, the conventional technology assumes a configuration in which the hydraulic oil tank and the fuel tank are provided separately on the left and right, and a single urea water tank is provided on the side of the fuel tank. The graph shown in Fig. 7 is for the case in which the fuel tank is heavier than the hydraulic oil tank, and if the hydraulic oil tank is heavier, the graph would be upside down.

[0044] As shown in Fig. 7, in the conventional technology, as time passes, the fuel in the fuel tank and the urea water in the urea water tank are consumed, so that the weight balance that was biased to the right is gradually corrected, and the left-right imbalance is corrected at time t2. After that, the fuel and urea water are further consumed, but the hydraulic oil does not decrease, so that the weight balance gradually becomes biased to the left.

[0045] On the other hand, in this embodiment, the urea water is initially supplied from the urea water tank 25R which is heavier on the left or right side of the vehicle body, so the weight difference between the left and right sides of the vehicle body gradually changes to zero (time t1). When the weight difference between the left and right sides of the vehicle body becomes zero, the left side of the vehicle body becomes heavier, so control is switched to supply urea water from the urea water tank 25L on the left side of the vehicle body. From that point on, the mass of the right side of the vehicle body decreases only by the amount of fuel consumed, so the slope of the decrease in the weight difference between the left and right sides of the vehicle body becomes gentler than in the conventional technology.

[0046] In this manner, according to the present embodiment, the controller 13 supplies either the urea water stored in the first urea water tank 25L or the urea water stored in the second urea water tank 25R to the NOx selective catalytic reduction device 35 based on the amount of hydraulic oil stored in the hydraulic oil tank 19, the amount of urea water stored in the first urea water tank 25L, the amount of fuel stored in the fuel tank 20, and the amount of urea water stored in the second urea water tank 25R, which are detected by the sensors 23, 26, and 27. More specifically, the controller 13 switches the urea water switching valve 21 so that the urea water is preferentially supplied from the urea water tank having the greater weight on the left or right side of the vehicle body, thereby adjusting the amount of urea water in each of the urea water tanks 25L and 25R. This makes it possible to reduce the imbalance in the weight balance between the left and right sides of the vehicle body. Furthermore, by dividing the urea water tank into two, the first urea water tank 25L and the second urea water tank 25R, it is possible to relax the design strength of the periphery of the fuel tank mounting portion of the body frame 30. This allows the frame structure to be optimized, and increases the degree of freedom in design.

[0047] Furthermore, since the weight balance between the left and right sides of the vehicle body can be well maintained, the total capacity of the urea water tanks 25L, 25R can be easily increased. If the capacity of the urea water tank can be easily increased, the number of times the urea water needs to be replenished can be reduced. In this embodiment, the first refill port 25L1 of the first urea water tank 25L and the second refill port 25R1 of the second urea water tank 25R are concentrated near the fuel tank 20, which improves the efficiency of maintenance work.

[0048] Second embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a configuration diagram of a urea water supply system according to the second embodiment, and Fig. 9 is a flowchart of urea water supply switching control according to the second embodiment. Note that the same reference numerals are used for configurations common to the first embodiment, and description thereof will be omitted.

[0049] 8, the urea water supply system 40-1 according to the second embodiment includes a urea water switching valve 21-1. The urea water switching valve 21-1 can be switched to three positions A, B, and C. Specifically, when the urea water switching valve 21-1 is switched to position A, the urea water 24 stored in the second urea water tank 25R is supplied to the urea water injector 22, when it is switched to position B, the urea water 24 stored in the first urea water tank 25L is supplied to the urea water injector 22, and when it is switched to position C, the urea water 24 stored in both urea water tanks 25L and 25R is supplied to the urea water injector 22.

[0050] Next, a description will be given of a control process of the urea water supply system according to the second embodiment. As shown in Fig. 9, in the second embodiment, process S4-1 and process S76 are added compared to the first embodiment.

[0051] Specifically, in steps S4-1 and S4-2, the controller 13 calculates the total weight M L (First total value) and total weight M R The absolute value of the difference ΔM between the second sums is compared with a reference value (predetermined range). In this embodiment, the reference value is, for example, the total weight M L and total weight M R However, this value is arbitrary.

[0052] If the controller 13 judges "Yes" in each of steps S4-1 and S4-2, the controller 13 executes step S5 or step S6 as in the first embodiment. On the other hand, if the controller 13 judges "No" in each of steps S4-1 and S-2, the controller 13 switches the urea water switching valve 21-1 to position C to supply the urea water 24 from the first urea water tank 25L and the second urea water tank 25R to the SCR muffler 10.

[0053] According to the second embodiment configured as described above, the change in the weight balance between the left and right sides of the vehicle body can be further suppressed. More specifically, when the absolute value of ΔM exceeds a reference value, urea water is consumed from the urea water tank on the heavier side of the left and right sides of the vehicle body, and the imbalance in the weight balance between the left and right sides of the vehicle body is eliminated. Then, when the absolute value of ΔM falls within the reference value (10% of the weight of both tanks), urea water is consumed from both the left and right urea water tanks, making it difficult for the weight balance between the left and right sides of the vehicle body to be reversed, and as a result, it becomes easier to maintain a good weight balance.

[0054] Next, modified examples of the first urea water tank 25L and the second urea water tank 25R will be described.

[0055] (Variation 1) Fig. 10 is a schematic diagram showing the structure of the urea water tank according to Modification 1. As shown in Fig. 10, Modification 1 is configured such that the first urea water tank 25L and the second urea water tank 25R are connected by a communication line 50, and a solenoid valve 51 is provided in the communication line 50. Then, while the dump truck is traveling (i.e., while the urea water supply systems 40, 40-1 are operating), the controller 13 switches the solenoid valve 51 to position D to block the communication line 50. This maintains a good weight balance between the left and right sides of the vehicle body.

[0056] Then, when the dump truck stops (i.e., the urea water supply systems 40, 40-1 stop) and urea water is to be replenished, the controller 13 switches the solenoid valve 51 to position E, thereby opening the communication pipe 50. Therefore, for example, when urea water is replenished from the second refill port 25R1 of the second urea water tank 25R, the urea water is also replenished to the first urea water tank 25L via the communication pipe 50. Therefore, according to the first modification, the urea water refilling operation is simplified.

[0057] (Variation 2) Fig. 11 is a schematic diagram showing the structure of a urea water tank according to Modification 2. As shown in Fig. 10, Modification 2 is configured such that the first urea water tank 25L and the second urea water tank 25R are connected by a communication line 50, and a check valve 52 is provided in the communication line 50. The check valve 52 allows the urea water to flow from the second urea water tank 25R to the first urea water tank 25L side (i.e., leftward in Fig. 11), while blocking the urea water from the first urea water tank 25L to the second urea water tank 25R side (i.e., leftward in Fig. 11).

[0058] While the dump truck is traveling, the controller 13 switches between the urea water tanks 25L, 25R that are supplied to the SCR muffler 10, thereby maintaining a good weight balance between the left and right sides of the vehicle body.

[0059] When the dump truck stops and urea water is to be replenished, when urea water is supplied to the second urea water tank 25R, the liquid level difference between the first urea water tank 25L and the second urea water tank 25R and the discharge pressure from a urea water filling pump (not shown) cause the urea water to flow to the first urea water tank 25L side via the check valve 52. Thus, according to the second modification, the urea water replenishment work is simplified.

[0060] It should be noted that the above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the gist of the present invention.

[0061] For example, in each of the above-described embodiments, the first urea water tank 25L and the second urea water tank 25R have the same capacity, but they may be different in capacity depending on the sizes of the hydraulic oil tank 19 and the fuel tank 20. For example, when the fuel tank 20 is heavier than the hydraulic oil tank 19 (weight of the hydraulic oil tank 19 < weight of the fuel tank 20), it is desirable to make the capacity of the first urea water tank 25L larger than the capacity of the second urea water tank 25R. This maintains a more uniform weight balance between the left and right sides of the dump truck 100. Conversely, when the hydraulic oil tank 19 is heavier than the fuel tank 20, it is desirable to make the capacity of the second urea water tank 25R larger than the capacity of the first urea water tank 25L. [Explanation of symbols]

[0062] 1 Engine 2. Generator 3L,3R rear wheel (wheel) 4L, 4R traction motor 5L,5R front wheel (wheel) 7 Pump Unit 8 resistor 9. Control Unit 10 SCR muffler 11 Cab 12 Indoor heating unit 13 Controller 14 ECU 15 Exhaust piping 16S Engine cooling water supply pipe 16R Engine coolant return pipe 17 Engine coolant branch valve 18L, 18R urea water pump 19 Hydraulic Oil Tank 20 Fuel Tank 20S urea water supply piping 20R Urea return pipe 21,21-1 Urea water switching valve 22 Urea water injection valve 23 Urea water sensor (sensor) 24 Urea solution (reducing agent) 25L 1st urea tank (1st reducing agent tank) 25L1 1st supply port 25L2 Supply line 25R Second urea tank (Second reducing agent tank) 25R1 2nd supply port 26,27 Level sensor (sensor) 30 Body frame (body) 31 Cargo platform (driven body) 32 Hoist cylinder (hydraulic actuator) 33 Exhaust Gas 35 NOx selective catalytic reduction device (exhaust gas purification device) 40,40-1 Urea water supply system 50 Communication pipeline 51 Solenoid valve 52 Check valve 100 Dump truck (transport vehicle)

Claims

1. A transport vehicle including a vehicle body, an engine for driving the vehicle body, a fuel tank for storing fuel to be supplied to the engine, a driven body provided on the vehicle body, a hydraulic actuator for driving the driven body, and a hydraulic oil tank for storing hydraulic oil to be supplied to the hydraulic actuator, an exhaust gas purification device that purifies exhaust gas from the engine; a first reducing agent tank and a second reducing agent tank for storing a reducing agent to be supplied to the exhaust gas purification device; sensors for detecting an amount of fuel stored in the fuel tank, an amount of hydraulic oil stored in the hydraulic oil tank, an amount of reducing agent stored in the first reducing agent tank, and an amount of reducing agent stored in the second reducing agent tank; A controller for controlling the exhaust gas purification device, the hydraulic oil tank and the first reducing agent tank are provided on one of the left and right sides of the vehicle body, the fuel tank and the second reducing agent tank are provided on the other of the left and right sides of the vehicle body, The controller: supplying to the exhaust gas purification device one of the reducing agent stored in the first reducing agent tank and the reducing agent stored in the second reducing agent tank based on the amount of hydraulic oil stored in the hydraulic oil tank, the amount of reducing agent stored in the first reducing agent tank, the amount of fuel stored in the fuel tank, and the amount of reducing agent stored in the second reducing agent tank, which are detected by the sensor; A transport vehicle characterized by:

2. 2. The transport vehicle according to claim 1, the second reducing agent tank has a second refill port for refilling the reducing agent, the first reducing agent tank is provided near the second refill port, and includes a first refill port for refilling the reducing agent, and a refill line connecting the first reducing agent tank and the first refill port. A transport vehicle characterized by:

3. 2. The transport vehicle according to claim 1, a communication pipe that communicates between the first reducing agent tank and the second reducing agent tank; a solenoid valve provided in the communication line, The controller: The solenoid valve is closed during operation of the exhaust gas purification device. When the exhaust gas purification device is stopped, the solenoid valve is controlled to be opened. A transport vehicle characterized by:

4. 2. The transport vehicle according to claim 1, a communication pipe that communicates between the first reducing agent tank and the second reducing agent tank; a check valve provided in the communication line, the check valve allows the reducing agent to flow from the second reducing agent tank to the first reducing agent tank side, while preventing the reducing agent from flowing from the first reducing agent tank to the second reducing agent tank side. A transport vehicle characterized by:

5. 2. The transport vehicle according to claim 1, The controller: comparing a first total value, which is a total of the current weights of the hydraulic oil tank and the first reducing agent tank, with a second total value, which is a total of the current weights of the fuel tank and the second reducing agent tank; When the difference between the first sum value and the second sum value is within a predetermined range, supplying the reducing agent from each of the first reducing agent tank and the second reducing agent tank to the exhaust gas purification device; A transport vehicle characterized by:

6. 2. The transport vehicle according to claim 1, When the weight of the fuel tank is greater than the weight of the hydraulic oil tank, the volume of the first reducing agent tank is made larger than the volume of the second reducing agent tank; When the weight of the hydraulic oil tank is greater than the weight of the fuel tank, the volume of the second reducing agent tank is made larger than the volume of the first reducing agent tank. A transport vehicle characterized by:

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