JP2014088860A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently carry out automatic regeneration.SOLUTION: In a work vehicle loading a diesel engine including a diesel particulate filter 46b collecting particulate matter PM in exhaust gas, an amount of the particulate matter PM in the diesel particulate filter 46b is calculated by a pressure sensor 52 on the upstream side of the diesel particulate filter 46b and a pressure sensor 53 on the downstream side, and automatic regeneration is carried out when the amount of the particulate matter PM exceeds the prescribed threshold. The engine is stopped during automatic regeneration, and an exhaust gas temperature when the engine is restarted is detected by a temperature sensor 59, and automatic regeneration interrupted by engine stop is carried out when the exhaust gas temperature is equal to or more than the prescribed value.

Description

  The present invention relates to a work vehicle equipped with a diesel engine equipped with a diesel particulate filter (DPF).

  When the diesel particulate filter (DPF) is regenerated, the DPF is continuously regenerated even if the engine is turned off (see, for example, Patent Document 1).

JP 2010-270611 A

  When regenerating the diesel particulate filter (DPF), the DPF regeneration is continued even if the engine is turned off. Therefore, the engine cannot be stopped at a scene where the engine drive is to be stopped, and the DPF regeneration is completed. I have to do it.

  The subject of this invention is providing the work vehicle carrying the diesel engine which eliminates the above malfunctions.

The above object of the present invention is achieved by the following configuration.
That is, according to the first aspect of the present invention, in a work vehicle equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in exhaust gas, the diesel particulate filter (46b) The amount of granulated material (PM) in the diesel particulate filter (46b) is calculated by the upstream pressure sensor (52) and the downstream pressure sensor (53). When the amount exceeds the threshold, automatic regeneration is performed. The engine is stopped during automatic regeneration, the exhaust gas temperature when the engine is started again is detected by the temperature sensor (59), and the exhaust gas temperature exceeds a predetermined value. If so, the work vehicle is configured to perform automatic regeneration that was interrupted when the engine was stopped.

  The operation of claim 1 is to stop the engine during automatic regeneration, detect the exhaust gas temperature when the engine is started again with the temperature sensor (59), and stop the engine if the exhaust gas temperature is above a predetermined value. The automatic playback that was interrupted is performed.

  According to a second aspect of the present invention, a parking brake switch (72) for braking the work vehicle and a PTO switch (73) for driving the work machine (21) connected to the work vehicle are provided. 72. The work vehicle according to claim 1, wherein automatic regeneration of the diesel particulate filter (46b) is prohibited when 72) is in the on state and the PTO switch (73) is in the off state. It is a thing.

  The action of claim 2 prohibits automatic regeneration of the diesel particulate filter (46b) when the parking brake switch (72) is in the on state and the PTO switch (73) is in the off state.

  According to the third aspect of the present invention, the fuel sensor (80) for detecting the amount of fuel in the fuel tank is provided, and the diesel particulate filter (46b) when the value detected by the fuel sensor (80) falls below a predetermined amount (F1). 2. The work vehicle according to claim 1, wherein the automatic regeneration is prohibited.

  The operation of claim 3 prohibits automatic regeneration of the diesel particulate filter (46b) when the value detected by the fuel sensor (80) becomes a predetermined amount (F1) or less.

Since the present invention is configured as described above, according to the first aspect of the present invention, the regeneration opportunity is increased by actively regenerating the DPF, and PM overdeposition can be prevented.
According to the second aspect of the present invention, it is possible to prevent exhaust of high-temperature exhaust gas in the vicinity where the work vehicle stops.

  In the invention of claim 3, it is possible to prevent the fuel from running out during the automatic regeneration. In addition, priority is given to work travel, so that the work can be continued with a small amount of remaining fuel.

Overall configuration diagram of accumulator fuel injection system Diagram showing the relationship between engine speed and output torque in control mode Left side view of tractor Top view of tractor Schematic diagram of intake and exhaust systems Flow chart of automatic regeneration at engine restart Control block diagram Flow chart of regeneration with remaining fuel Relationship between remaining fuel and prohibition of regeneration Relationship between regeneration and cooling water temperature Top view of meter panel

The best mode for carrying out the present invention will be described.
FIG. 1 is an overall configuration diagram of a pressure accumulation type fuel injection device. The accumulator fuel injection device is applied to, for example, a multi-cylinder diesel engine, but may be a gasoline engine. The accumulator fuel injection device pressurizes the common rail 1 that accumulates high-pressure fuel corresponding to the injection pressure, the pressure sensor 2 attached to the common rail 1, and the fuel pumped up from the fuel tank 3, and pumps the fuel to the common rail 1. A high-pressure pump 4, a fuel injection nozzle 6 for injecting high-pressure fuel accumulated in the common rail 1 into the cylinder 5 of the engine E, a control device (ECU) for controlling the operation of the high-pressure pump 4, the fuel injection nozzle 6 and the like Consists of ECU is an abbreviation for engine control unit.

Thus, the common rail 1 injects fuel to each cylinder 5 of the engine E, and makes the fuel supply a required pressure.
The fuel in the fuel tank 3 is sucked into the high-pressure pump 4 driven by the engine E through the fuel filter 7 through the suction passage, and the high-pressure fuel pressurized by the high-pressure pump 4 is guided to the common rail 1 through the discharge passage 8. Stored.

  The high-pressure fuel in the common rail 1 is supplied to the fuel injection nozzles 6 for the number of cylinders through the high-pressure fuel supply passages 9, and the fuel injection nozzles 6 are operated to the respective cylinders based on commands from the ECU 100. The surplus fuel (return fuel) from each fuel injection nozzle 6 is guided to a common return passage 10 by each return passage 10 and returned to the fuel tank 3 by this return passage 10.

  In addition, a pressure control valve 11 is provided in the high-pressure pump 4 to control the fuel pressure (common rail pressure) in the common rail 1. The pressure control valve 11 is connected to the fuel tank 3 from the high-pressure pump 4 by a duty signal from the ECU 100. The flow area of the return passage 10 for surplus fuel to the fuel is adjusted, whereby the amount of fuel discharged to the common rail 1 side can be adjusted to control the common rail pressure.

  Specifically, the target common rail pressure is set according to the engine operating conditions, and the common rail pressure is feedback-controlled through the pressure control valve 11 so that the common rail pressure detected by the rail pressure sensor 2 matches the target common rail pressure. It is configured.

  As shown in FIG. 2, the ECU 100 of the diesel engine E having the common rail 1 in the work vehicle (agricultural work machine) has three types of modes, a travel mode A, a normal work mode B, and a heavy work mode C in relation to the rotational speed and the output torque. The configuration has a control mode.

  The traveling mode A is droop control in which the output also varies with the variation of the engine speed. It is used when traveling without farming. For example, when the traveling speed is reduced or stopped by applying a brake, the engine speed decreases with an increase in the traveling load, so that the traveling speed can be safely reduced or stopped.

  The normal work mode B is isochronous control in which the engine speed is constant and the output is changed according to the load even when the load varies. It is used for normal farm work. For example, if it is a tractor, it is when the cultivated land is hard during plowing work and resistance is applied to the plowing blade. Is the time.

  In the heavy work mode C, in addition to the isochronous control in which the engine speed is constant and the output is changed according to the load even when the load fluctuates in the same manner as the normal work mode B, the engine speed is increased when the load is close to the limit. This is a control with heavy load control that increases In particular, it is used when farming near the load limit. For example, when plowing with a tractor, the engine output increases beyond the normal limit even when encountering hard cultivated land, so work can be performed efficiently without interruption. .

  These work modes A, B, and C are operations of a work mode changeover switch that can switch between the work modes A, B, and C, or a shift operation of a traveling speed change lever of a farm vehicle (tractor, combine, rice transplanter, etc.) Alternatively, it is configured to be switched by an on / off operation or the like of a work clutch (rotary if it is a tractor, and mowing part or threshing part if it is a combine).

  In diesel engine E, pilot injection that injects a small amount of fuel in a pulse manner prior to main injection makes it possible to shorten the ignition delay, reduce the knocking noise peculiar to diesel engine E, and reduce noise It has a simple structure.

  This pilot injection is performed only once or twice before the main injection. By using the accumulator fuel injection device of the common rail 1, pilot injection is performed according to the situation of the engine E. Thus, it becomes possible to reduce the noise and the generation of white smoke or black smoke due to incomplete combustion. Further, by performing pilot injection in which a small amount of fuel is pulse-injected prior to main injection, the amount of nitrogen oxides in the exhaust gas is reduced.

  FIG. 3 shows a side view of a tractor equipped with a diesel engine having the common rail 1 as described above, and FIG. 4 shows a plan view thereof. In the plan view, the cabin 14 shown in FIG. 3 is omitted.

  The tractor includes front wheels 12 and 12 and rear wheels 13 and 13 at the front and rear portions of the fuselage, and the rotational power of the engine E mounted on the front portion of the fuselage is appropriately decelerated by a transmission in the transmission case T so that the front wheels 12 , 12 and the rear wheels 13, 13.

  A steering handle 16 is supported on the handle post 15 in the cabin 14 at the center of the body, and a seat 17 is provided behind the steering handle 16. A forward / reverse lever 18 is provided below the steering handle 16 to switch the advancing direction of the aircraft to the front / rear direction. When the forward / reverse lever 18 is moved to the front side, the aircraft moves forward, and when it is moved backward, the aircraft moves backward.

  An accelerator lever 25 for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 18 with the handle post 15 in between, and an accelerator for similarly adjusting the engine speed is provided at the right corner of the step floor 19. The pedal 23 and left and right brake pedals 24L, 24R for operating the left and right rear wheels 13, 13 are provided. A clutch pedal 20 is provided at the left corner of the step floor 19.

  The main transmission lever 26 is located at the left front portion of the seat 17, the auxiliary transmission lever 27 capable of selecting any of the low speed, medium speed, high speed and neutral positions is located behind the main transmission lever 26, and further on the right side thereof is the PTO transmission lever 28. Is provided. Further, on the right side of the seat 17, a position lever 29 for setting the height of the working machine 21 (rotary or the like), an automatic tilling lever 30 for automatically setting the tilling depth of the field, and the working machine 21 after these levers. The right-up switch 31 and the right-down switch 32 are arranged, and then the automatic horizontal switch 33 and the backup switch 34 of the work machine 21 are arranged. The backup switch 34 automatically raises the work machine 21 when the machine moves backward. The work machine 21 has a configuration in which a link 22 is connected to the rear of the machine body. The tractor performs work such as tillage in the field by driving the work machine 21 and running the machine body. 21a is a hydraulic cylinder which raises and lowers the working machine 21.

  FIG. 5 is a schematic diagram of intake and exhaust into the cylinder 5 of the engine, which is an embodiment of a four-cycle diesel engine. The air supercharged by the intake turbine 36 of the supercharger TB passes through the intake turbine 36 and the intercooler 37 from the air cleaner 35 and is sent from the intake manifold 38 into the cylinder 5. Reference numeral 39 is an intake valve, and 40 is a piston. A cam 48 opens and closes the intake and exhaust valves 39 and 41 via a rocker arm 49.

The exhaust gas combusted in the cylinder 5 passes through the exhaust manifold 42 from the exhaust valve 41 and is then discharged by driving the supercharger TB with the exhaust turbine 45 of the supercharger TB.
The diesel engine has an EGR (exhaust gas recirculation device) circuit 44 for mixing a part of the exhaust gas into the intake side. In the EGR circuit, a part of the exhaust gas is mixed into the intake side to reduce the amount of oxygen (O2), thereby reducing the generation of nitrogen oxide Nox. However, if the EGR rate increases too much, the amount of oxygen decreases and incomplete combustion occurs. Therefore, it is necessary to adjust the EGR rate according to the combustion state. This adjustment is performed by the EGR valve 43. The EGR circuit 44 connects between an exhaust pipe 55 on the downstream side of a post-processing device 46 described later and an intake pipe 56 on the upstream side of the intake turbine 36 of the supercharger TB. In addition, an EGR cooler 57 is provided in the middle of the EGR circuit 44. The amount of exhaust gas reduced into the cylinder 5 varies depending on how the EGR valve 43 is opened and closed.

  The exhaust gas that has passed through the exhaust turbine 45 passes through the aftertreatment device 46 and is discharged from the muffler 50 into the atmosphere. The post-processing device 46 includes an oxidation catalyst (DOC) 46a and a diesel particulate filter (DPF) 46b.

  The oxidation catalyst (DOC) burns the incombustible chamber, and the diesel particulate filter (DPF) is for collecting the particulate matter (PM). The EGR valve 43 and the throttle valve 47 are controlled by the ECU 100. The post-processing device 46 may be composed of only a diesel particulate filter (DPF) 46b. If an oxidation catalyst (DOC) is provided, the non-combustible material burns, resulting in cleaner exhaust gas.

  When the state of the exhaust gas is low (low load) continues for a long time, the DPF 46b has a concern that PM will accumulate and the capacity may be reduced. Therefore, a throttle valve 47 is provided on the lower side of the post-processing device 46, and when the throttle valve 47 is throttled, the pressure in the DPF 46b is kept high, so the temperature also rises. This makes it possible to regenerate the DPF 46b due to the influence of a high temperature. That is, when exhaust gas having a high temperature passes through the DPF 46b, the DPF 46b is regenerated by burning off the PM present in the DPF 46b.

  In the DPF regeneration operation for regenerating the DPF 46b, both the EGR valve 43 and the throttle valve 47 are throttled. Then, the gas temperature in the DPF 46b is raised together with the retard (retard) of the fuel injection timing so that the DPF 46b starts to be regenerated. This eliminates the need for fuel after-injection (in order to increase the exhaust gas temperature) or reduces the number of after-injections, so that the amount of fuel consumption can be suppressed and the environment is good.

  As a condition for performing such a DPF regeneration operation, the pressure sensor 52 is provided on the upper side of the post-processing device 46, the pressure sensor 53 is provided on the lower side of the post-processing device 46, and this pressure difference is a predetermined value or more. Then, since PM accumulates in the DPF 46b and becomes a resistance, the DPF regeneration operation is performed. Moreover, it is good also as a structure which provides the pressure sensor 58 between DOC46a and DPF46b instead of the pressure sensor 52. FIG.

  Further, if the state in which the DPF regeneration operation is started continues for a long time, the DPF 46b is damaged due to an overheating state. Therefore, a temperature sensor 59 is provided on the lower side of the post-processing device 46, and when the value of the temperature sensor 59 exceeds a predetermined value, the DPF regeneration operation is stopped and the normal operation is resumed.

  In normal operation, the EGR valve 43 and the throttle valve 47 are simultaneously controlled to appropriately control the EGR amount. In particular, by having the throttle valve 47, the gas temperature in the DPF 46b can be kept high.

  With the configuration as described above, an intake throttle is not required. In other words, since the intake side pressure is high in an engine with a supercharger, an exhaust throttle valve or an intake throttle is required to secure the amount of EGR gas, and control in conjunction with the EGR valve is required, but such a system is unnecessary. It becomes.

  Further, since the exhaust gas downstream of the DPF 46b is taken out, it is possible to prevent the performance deterioration caused by the dirt of the supercharger TB. And since EGR gas is cooled by the EGR cooler 57, an effect becomes large with respect to NOx reduction.

  As described above, in the DPF forced regeneration mode in which the regeneration operation of the DPF is performed, the exhaust throttle valve 47 is throttled and the EGR valve 43 is fully closed by ON-OFF control. Therefore, NO is increased because the exhaust gas is not reduced, and this NO is converted to NO2 by the oxidation catalyst (DOC) 46a, and regeneration of the DPF 46b is promoted.

  Further, when the engine rotation shifts to low idle during the forced regeneration of the DPF 46b, the EGR valve 43 is fully opened. Since the temperature sensor 59 is provided on the downstream side of the DPF 46b, it may be added to the condition that the detection value by the temperature sensor 59 has risen to a predetermined value or more.

  When the DPF 46b is forcibly regenerated by restricting the throttle valve 47, the engine speed is reduced to increase the supply oxygen amount, and the exhaust gas flow rate is decreased to increase the temperature easily. However, when the engine speed is changed to low idle or in the vicinity thereof during regeneration, soot burns rapidly due to an increase in the amount of supplied oxygen and a decrease in the flow velocity. As a result, the temperature may rise rapidly and the DPF 46b may be damaged. Therefore, it is necessary to manage the soot that the maximum temperature does not exceed the allowable temperature.

  For this reason, when the temperature sensor 59 exceeds a predetermined value, the engine speed is increased to a medium speed range. As a result, the flow rate of the exhaust gas is increased, so that the maximum temperature is lowered and damage to the DPF 46b can be prevented. Further, when the predetermined value of the temperature sensor 59 is controlled in the vicinity of the limit value, the DPF 46b can be efficiently regenerated.

  In order to increase the engine speed to the middle speed range, it may be configured to once increase to the maximum speed and then decelerate to the middle speed range, so that the exhaust gas once flows at the maximum speed. For example, it is possible to prevent the DPF 46b from being heated and exceeding the threshold temperature.

  Further, during the forced regeneration of the DPF 46b, when the engine speed is shifted to low idle as described above, the post-injection is interrupted, and then the engine speed is increased to the maximum speed and shifted to the medium speed range. Then, post-injection is resumed. Thereby, since the rapid rise in the exhaust gas temperature can be suppressed, damage to the DPF 46b can be prevented.

  When the differential pressure across the DPF 46b exceeds a predetermined value, the driver selects the regeneration mode of the DPF 46b after the operation with the selection switch 67, so that the DPF 46b is automatically regenerated. After the DPF 46b is regenerated, the engine is automatically stopped. To be configured. The differential pressure across the DPF 46b is monitored by pressure sensors 58 and 53. If the differential pressure across the DPF 46b immediately before the engine stops is equal to or greater than a predetermined value, a warning lamp or alarm notifies the driver, and the driver operates a switch (not shown) for regenerating the DPF 46b.

  Even when the engine key is in the cut position, since the regeneration mode is selected, the engine keeps rotating in the idling state and performs regeneration of the DPF 46b. When the differential pressure before and after the DPF 46b falls below a predetermined value, the engine is automatically stopped.

Thus, even after the work is completed, the DPF 46b can be automatically regenerated and the engine can be stopped, so that the driver can leave the machine and perform other work.
When the DPF 46b is regenerated, the intake side air may be sent from the pipe 61 to the upstream side of the DPF 46b as shown in FIG. That is, when the DPF 46b is regenerated, the valve 60 may be opened so that the intake air on the upstream side of the turbocharger TB having a large amount of oxygen is sent to the upstream side of the DPF 46b. Thereby, the reproduction efficiency is improved.

  Alternatively, the temperature of the DPF 46b may be monitored by the temperature sensors 62 and 59, and the temperature increase during regeneration may be confirmed in three steps. First, the intake is throttled (not shown), and the temperature rise in the throttled state of intake is confirmed. Next, the first post injection is performed to check the temperature rise. At this time, if the temperature before and after the DPF 46b does not reach 250 degrees, further temperature rise cannot be expected even if the second post-injection is performed. Therefore, the regeneration is temporarily interrupted. Of course, if it is 250 degrees or more, the second post injection is performed to regenerate the DPF 46b.

  As shown in FIG. 5, an air-fuel ratio sensor 63 is provided on the downstream side of the DPF 46b. When the post-injection is performed to regenerate the DPF 46b, if the fuel injection amount is too large, the fuel consumption is deteriorated. If the fuel injection amount is small, the temperature does not increase and the regeneration cannot be performed. Therefore, the injection amount is determined by feeding back the value of the air-fuel ratio sensor 63 to the ECU 100. As a result, the fuel consumption becomes appropriate and the DPF 46b can be regenerated. Further, instead of the air-fuel ratio sensor 63, a pressure value in the intake manifold may be fed back.

  When regenerating the DPF 46b as described above, in the case of a plurality of cylinders, the combustion of some cylinders may be stopped. Thus, by stopping the combustion of some cylinders, the exhaust temperature may be increased by increasing the load per cylinder even if the engine friction is the same.

  As described above, regeneration of the DPF 46b includes automatic regeneration and forced regeneration (manual regeneration). Automatic regeneration is regeneration under specific conditions during traveling (on the road and in the field), and forced regeneration (manual regeneration) is performed when the threshold of the amount of PM in the DPF 46b exceeds a limit value, Is stopped and playback is performed.

  During the automatic regeneration, when the engine is stopped and restarted again, the automatic regeneration is resumed if the temperature in the DPF 46b is a high temperature state equal to or higher than a predetermined value. Even if the load is low and the load for carrying out normal automatic regeneration is not reached, the automatic regeneration is restarted immediately. As a result, regeneration opportunities are increased and regeneration is performed actively, so that the amount of PM in the DPF 46b can be prevented from being excessively deposited. Further, since the efficiency of regeneration of the DPF 46b is improved, the amount of fuel dilution entering the engine oil can be reduced. FIG. 6 shows a flowchart.

  Further, a switch 71 for switching automatic reproduction permission / prohibition is provided. When prohibition is selected by the automatic reproduction permission prohibition switch 71, automatic reproduction is prohibited. Further, when the parking brake switch 72 is turned on (airframe stop state) and the PTO switch for driving the work machine is turned off (external power stop), automatic regeneration is prohibited. In other words, the automatic regeneration is not performed when a state where the work machine is not moved while the vehicle is stopped continues for a predetermined time or longer. Thus, for example, it is assumed that the vehicle is stopped in a narrow garage, and by prohibiting automatic regeneration, it is possible to prevent high-temperature exhaust gas from being ignited by a nearby flammable gas.

  FIG. 8 and FIG. 9 are explanatory diagrams about prohibition of automatic regeneration and manual regeneration with residual fuel. When the remaining amount of fuel by the fuel sensor 80 (FIG. 7) is equal to or greater than the threshold value F1, automatic regeneration is permitted for manual regeneration. When the remaining amount of fuel falls below the threshold value F1, automatic regeneration is prohibited and manual regeneration is permitted. When the remaining amount of fuel falls below the threshold value F2, manual regeneration is also prohibited. Thereby, it becomes possible to prevent gas shortage during regeneration. Moreover, by allowing the manual regeneration to be performed until the remaining amount of fuel decreases, the opportunity for regeneration increases, and the amount of PM in the DPF 46b can be prevented from being excessively deposited.

  FIG. 10 will be described. When the amount of PM accumulated in the DPF 46b increases and the region P1 where it is necessary to regenerate the DPF, the threshold value of the engine coolant temperature for permitting regeneration is decreased as the amount of PM accumulated increases. To do. Thereby, the opportunity to implement regeneration increases and PM can be prevented from being excessively deposited. In addition, even when the water temperature is unlikely to rise due to a malfunction of the thermostat, it becomes easier to carry out the regeneration.

  Further, the tractor equipped with the GPS 74 (FIG. 7) is configured to prohibit automatic reproduction when the current position information detected by the GPS matches the preset position information S1. The preset position information S1 is a place where, for example, high temperature exhaust gas is exhausted. Since a fire may occur when hot exhaust gas hits a small barn or the like, such a place is specified in advance. Moreover, you may comprise so that it may prohibit also in a city area etc.

  Further, in addition to the GPS position information S1, manual regeneration or automatic regeneration is performed by detecting that the distance sensor from the exhaust pipe is a narrow place or detecting a dark place such as a barn by an illuminance sensor. May be configured to be prohibited. Moreover, you may comprise so that a warning message may be output.

  FIG. 11 shows a tractor meter panel 75. Reference numeral 76 denotes an engine rotation system, reference numeral 77 denotes a liquid crystal panel for displaying various information, and reference numeral 78 denotes various warning lights. Reference numeral 79 denotes a manual regeneration switch that performs manual regeneration, and has a rod-like switch configuration that penetrates the surface cover of the meter panel 75. This makes it easier to see the manual regeneration switch.

  It can be used for farm vehicles such as tractors and combiners as well as general vehicles.

PM Granulated material 21 Work machine 46b Diesel particulate filter (DPF)
52 Upstream pressure sensor 53 Downstream pressure sensor 59 Temperature sensor 72 Parking brake switch 73 PTO switch 80 Fuel sensor

Claims (3)

  In a work vehicle equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in exhaust gas, a pressure sensor (52) upstream of the diesel particulate filter (46b); The amount of granulated material (PM) in the diesel particulate filter (46b) is calculated by the downstream pressure sensor (53), and automatic regeneration is performed when the amount of granulated material (PM) exceeds a predetermined threshold. The engine is stopped during automatic regeneration, the exhaust gas temperature when the engine is started again is detected by the temperature sensor (59), and if the exhaust gas temperature is equal to or higher than a predetermined value, the engine is stopped when the engine is stopped. A work vehicle that is configured to perform automatic regeneration.   A parking brake switch (72) for braking the work vehicle, and a PTO switch (73) for driving the work machine (21) connected to the work vehicle, wherein the parking brake switch (72) is in an on state, The work vehicle according to claim 1, wherein when the PTO switch (73) is in the off state, automatic regeneration of the diesel particulate filter (46b) is prohibited.   A fuel sensor (80) for detecting the amount of fuel in the fuel tank, and prohibiting automatic regeneration of the diesel particulate filter (46b) when a value detected by the fuel sensor (80) falls below a predetermined amount (F1); The work vehicle according to claim 1, wherein

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