Exhaust gas purification device, exhaust gas purification method, and control device

Abstract

To properly control a degree of opening of an exhaust throttle valve.SOLUTION: An exhaust emission purification device comprises: a throttle valve arranged in a path in which an exhaust gas discharged from an engine whose rotation number is controlled in response to an operation of an accelerator flows; a diesel engine oxidation catalyst device arranged downstream of the throttle valve; a selective reduction catalyst device arranged downstream of the diesel engine oxidation catalyst device; a fuel injection device for injecting fuel upstream of the diesel engine oxidation catalyst device; and a control device to which temperature data indicating an inlet temperature and an outlet temperature of the diesel engine oxidation catalyst device are input and controls the throttle valve and the fuel injection device. When performing control for throttling the throttle valve, the control device changes an upper limit value on a degree of valve opening when a fully closed state of the throttle valve is defined as a maximum value of the degree of valve opening and a fully open state of the throttle valve is defined as a minimum value, on the basis of a determination result based on the degree of opening of the accelerator and operation states of one or more operation devices which are different from the accelerator.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0005]

[0001] The present disclosure relates to an exhaust gas purification device, an exhaust gas purification method, and a control device.

Background Art

[0002] Patent Documents 1 to 3 disclose technologies for raising the temperature of exhaust gas by controlling an exhaust throttle valve (throttle valve) or the like provided in the exhaust path of a diesel engine, and regenerating an exhaust gas purification device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as described in Patent Document 3, since the exhaust throttle valve is provided in the path through which the exhaust gas discharged from the engine flows, the operating environment is less stable than that of the intake throttle valve provided in the intake path that supplies air to the engine. Therefore, there is a risk that, for example, the exhaust gas may become high temperature and high pressure when the opening degree of the exhaust throttle valve is reduced. Therefore, in the control of reducing the opening degree of the exhaust throttle valve, there is a problem that it is necessary to appropriately control the opening degree so as not to damage components such as the engine and the post-treatment device.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an exhaust gas purification device, an exhaust gas purification method, and a control device that can appropriately control the opening degree of an exhaust throttle valve. [Means for solving the problem]

[0006] To solve the above problems, one aspect of the present invention is an exhaust gas purification device comprising: a throttle valve provided in a path through which exhaust gas discharged from an engine whose rotational speed is controlled according to the operation of an accelerator flows; a diesel oxidation catalyst device disposed downstream of the throttle valve; a selective reduction catalyst device disposed downstream of the diesel oxidation catalyst device; a fuel injector that injects fuel upstream of the diesel oxidation catalyst device; an inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device; an outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device; and a control device that receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injector, wherein when the control device executes control to throttle the throttle valve, it changes the upper limit of the valve opening, where the fully closed state of the throttle valve is the maximum value of the valve opening and the fully open state is the minimum value of the valve opening, based on a determination result based on the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator.

[0007] Furthermore, one aspect of the present disclosure is a control method for an exhaust gas purification device, comprising: a throttle valve provided in a path through which exhaust gas discharged from an engine whose rotational speed is controlled according to the operation of an accelerator flows; a diesel oxidation catalyst device disposed downstream of the throttle valve; a selective reduction catalyst device disposed downstream of the diesel oxidation catalyst device; a fuel injector that injects fuel upstream of the diesel oxidation catalyst device; an inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device; an outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device; and a control device that receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injector, wherein when control to throttle the throttle valve is performed, the upper limit of the valve opening is changed based on a determination result based on the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator, with the fully closed state of the throttle valve being the maximum value of the valve opening and the fully open state being the minimum value of the valve opening.

[0008] Furthermore, one aspect of the present disclosure is an exhaust gas purification device comprising: a throttle valve provided in a path through which exhaust gas discharged from an engine whose rotational speed is controlled according to the operation of an accelerator flows; a diesel oxidation catalyst device disposed downstream of the throttle valve; a selective reduction catalyst device disposed downstream of the diesel oxidation catalyst device; a fuel injector that injects fuel upstream of the diesel oxidation catalyst device; an inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device; and an outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device, wherein the control device receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injector, and when executing control to throttle the throttle valve, the control device changes the upper limit of the valve opening, where the fully closed state of the throttle valve is the maximum value of the valve opening and the fully open state is the minimum value of the valve opening, based on a determination result based on the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator. [Effects of the Invention]

[0009] According to each aspect of this disclosure, the opening degree of the exhaust throttle valve can be appropriately controlled. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram of a work vehicle equipped with an exhaust gas purification device according to one embodiment of the present disclosure. [Figure 2] A block diagram showing an example configuration of the operating device. [Figure 3] A block diagram showing an example of the control device configuration. [Figure 4] A flowchart illustrating temperature rise control in a control device. [Figure 5] A schematic diagram showing examples of control conditions in temperature rise control. [Figure 6] A graph showing an example of how an exhaust gas purification system works. [Figure 7] A graph showing an example of how an exhaust gas purification system works. [Figure 8]Flowchart showing automatic playback control in the control device. [Figure 9] Schematic diagram showing an example of vehicle safety state conditions. [Figure 10] Schematic diagram showing an example of vehicle safety state conditions. [Figure 11] Schematic diagram showing an example of vehicle safety state conditions. [Figure 12] Schematic diagram showing an example of ETV opening MAP1. [Figure 13] Schematic diagram showing an example of ETV opening MAP2. [Figure 14] Graph showing an example of the operation of the exhaust gas purification device.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a work vehicle equipped with an exhaust gas purification device according to an embodiment of the present disclosure. FIG. 2 is a block diagram showing a configuration example of an operation device. FIG. 3 is a block diagram showing a configuration example of a control device. FIG. 4 is a flowchart showing temperature increase control in the control device. FIG. 5 is a schematic diagram showing an example of each condition in temperature increase control. FIGS. 6 and 7 are graphs showing an example of the operation of the exhaust gas purification device. FIG. 8 is a flowchart showing automatic regeneration control in the control device. FIGS. 9 to 11 are schematic diagrams showing examples of vehicle safety state conditions. FIG. 12 is a schematic diagram showing an example of ETV opening MAP1. FIG. 13 is a schematic diagram showing an example of ETV opening MAP2. FIG. 14 is a graph showing an example of the operation of the exhaust gas purification device. In each figure, the same or corresponding configurations are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0012] [Schematic Configuration of Exhaust Gas Purification Device] FIG. 1 schematically shows a schematic configuration of a work vehicle 1 including an exhaust gas purification device 10 according to the present embodiment. Here, the work vehicle 1 is, for example, a work machine that performs operations such as excavation and land leveling and transportation of earth and sand at a construction site such as a mine or a road, and examples include construction machines such as hydraulic excavators, wheel loaders, bulldozers, motor graders, and cranes, and transport vehicles such as dump trucks and forklifts. Note that since the exhaust gas purification device 10 of the present embodiment purifies the exhaust gas of a diesel engine, it can be used not only for the work vehicle 1 but also for various vehicles and devices equipped with a diesel engine. The work vehicle 1 includes a diesel engine 2 (hereinafter also referred to as an engine), a turbocharger 3 that compresses air supplied to the diesel engine 2 by rotating a turbine with the exhaust gas of the diesel engine 2, a control device 8, a monitor 9, a vehicle controller 73, an operation device 60, and an exhaust gas purification device 10.

[0013] The diesel engine 2 is provided with an engine speed detection device 6 that detects the engine speed and a fuel injection device 7 that injects fuel into the diesel engine 2. The detection data of the engine speed detection device 6 is output to the control device 8. Further, the control device 8 controls the fuel injection device 7 according to an accelerator operation or the like.

[0014] [Monitor] The monitor 9 comprises a display unit and an input unit. The display unit is composed of a liquid crystal display or the like. The display unit displays various information such as coolant temperature, fuel level, and cautions. The monitor 9 of this embodiment is provided with a notification unit 91 that prompts the operator to perform stationary manual regeneration, as described later, and the monitor 9 functions as a notification device that notifies the operator of various information. The input unit is composed of switches (buttons) or the like provided around the display unit. The function of each input unit is displayed on the display unit with icons or the like. Therefore, the operator can easily understand which switch to press when performing stationary manual regeneration. If a touch panel type monitor 9 is used, the operator can simply touch the switch displayed on the touch panel. The monitor 9 of this embodiment is provided with a switch (also called a stationary manual regeneration switch) 92 that instructs the operator to perform stationary manual regeneration. The input unit is not limited to switches provided integrally with the monitor 9, but may also consist of switches installed in a separate housing or the like from the monitor 9.

[0015] [Exhaust purifying device] The exhaust gas purification device 10 processes residual substances such as particulate matter (PM) and NOx (nitrogen oxides) in the exhaust gas, including collection and reduction, and is controlled by the control device 8. The exhaust gas purification device 10 comprises, in order from the upstream side in the flow direction of the exhaust gas discharged from the diesel engine 2, an exhaust throttle valve (hereinafter also called a throttle valve or ETV (Exhaust Throttle Valve)) 20, a fuel injection device 72, a DPF device 71, a urea water injection system 40, and a selective catalytic reduction (SCR) device 50. The DPF device 71 comprises a diesel oxidation catalyst (DOC) device 30 and a DPF (Diesel Particulate Filter) 70. These DPF device 71, urea water injection system 40, and SCR device 50 are installed in the middle of the path 11 through which exhaust gas from the diesel engine 2 flows. This path 11 includes an inlet pipe 12 that introduces exhaust gas from the turbocharger 3 connected to the diesel engine 2 into the DPF device 71, an outlet pipe 13 that connects the DPF device 71 and the SCR device 50, and an outlet pipe 14 connected to the outlet of the SCR device 50. The outlet pipe 13 also has a mechanism for diffusing the urea water supplied from the urea water injection system 40.

[0016] [Throttle valve] The throttle valve 20 is composed of a butterfly valve or the like located in the inlet pipe 12. The valve opening of the throttle valve 20 is controlled by the control device 8, and as will be described later, the temperature of the exhaust gas is adjusted by adjusting the valve opening. That is, when the valve opening is reduced, the exhaust gas is compressed in front of the throttle valve 20, and the pressure and temperature of the exhaust gas flowing through the exhaust passage increase. In this case, the control device 8 sets a target torque value for the engine based on, for example, the accelerator opening, and controls the valve opening of the throttle valve 20 using map (also called "MAP") data that sets the valve opening using the set target torque value and engine rotation speed as elements. However, the map data may also be, for example, map data that sets the valve opening using fuel injection amount and engine rotation speed as elements. Specifically, when the torque is small, that is, when the engine load is small, the temperature of the exhaust gas also decreases. Also, when the engine rotation speed is small, the temperature of the exhaust gas decreases. Here, if the valve opening of the throttle valve 20 is set to 100% for the fully closed state and 0% for the fully open state, then in the region where the torque is below a predetermined value, the valve opening of the throttle valve 20 is set to increase as the torque decreases and decrease as the torque increases, and to increase as the engine speed decreases and decrease as the engine speed increases. For example, when the torque is low and the engine speed is low, the valve opening should be set to about 90%, and when the torque is high and the engine speed is high, the valve opening should be set to a smaller value (for example, about 60%). In this way, when the engine load is low, that is, when the temperature does not rise easily, the valve is partially closed (valve opening is increased) to increase the pressure resistance of the exhaust gas and raise the temperature of the exhaust gas. Note that even when the valve opening of the throttle valve 20 is set to 100%, there is a structural gap remaining, so the inlet pipe 12 is not completely closed.

[0017] [DPF device] The DPF unit 71 comprises a DOC unit 30 and a DPF 70. The DPF 70 collects PM, and the nitrogen dioxide converted by the DOC unit 30 oxidizes the collected PM downstream to carbon dioxide, thereby removing the PM.

[0018] [DOC device] The DOC device 30 comprises a case, and a diesel oxidation catalyst is housed inside the case. The DOC device 30 is a catalyst that oxidizes and generates heat in the fuel supplied to the exhaust gas as needed (hereinafter referred to as dosing fuel; the supply of dosing fuel is also referred to as fuel dosing), raising the exhaust gas temperature to a predetermined high-temperature range. By utilizing this heated exhaust gas, for example, urea deposits accumulated in the outlet pipe 13, etc., described later, are decomposed, removed, and regenerated. The dosing fuel is, for example, diesel fuel, the same as the engine fuel. When dosing fuel is supplied into the engine cylinder, the dosing fuel is supplied by post-injection using the fuel injector 7 for in-engine cylinder injection. In this embodiment, fuel can also be supplied into the exhaust gas by a dosing fuel injector 72 provided in the inlet pipe 12, and the fuel can flow into the DOC device 30 together with the exhaust gas. The fuel injector according to this disclosure corresponds to at least one of the fuel injector 7 and the fuel injector 72.

[0019] [Urea solution injection system] The urea water injection system 40 adds an aqueous urea solution as a reducing agent to the exhaust gas. This urea water injection system 40 is attached to the outlet pipe 13 of the DPF device 71 and includes an injection nozzle 41 that injects the aqueous urea solution into the outlet pipe 13, a urea water tank 42 that stores the aqueous urea solution, and a pump unit 43 that supplies the aqueous urea solution from the urea water tank 42 to the injection nozzle 41. The control device 8 controls the injection nozzle 41 and the pump unit 43, injecting the aqueous urea solution from the injection nozzle 41 into the outlet pipe 13. The aqueous urea solution injected into the outlet pipe 13 is hydrolyzed by the heat of the exhaust gas to become ammonia.

[0020] [SCR device] The SCR device 50 reduces and purifies nitrogen oxides in exhaust gas by using ammonia, obtained by hydrolyzing an aqueous urea solution, as a reducing agent. Ammonia is supplied to the SCR device 50 along with the exhaust gas as a reducing agent. An ammonia oxidation catalyst may also be provided downstream of the SCR device 50. The ammonia oxidation catalyst oxidizes and detoxifies the ammonia that remains unused in the SCR device 50, further reducing exhaust gas emissions. When the aqueous urea solution is injected from the injection nozzle 41, urea may crystallize and precipitate in the outlet pipe 13. Therefore, it is necessary to perform a regeneration treatment to decompose the precipitate (urea deposit) in the outlet pipe 13 by raising the exhaust gas temperature. The regeneration treatment includes automatic regeneration control, which is performed automatically when the work vehicle is operating, and stationary manual regeneration, which is performed by the operator's manual operation. These are switched and selected and controlled by the control device 8.

[0021] [Sensor] The exhaust gas purification device 10 is equipped with various sensors to detect the status of the diesel engine 2 and the exhaust gas purification device 10. Specifically, a NOx sensor 32 for detecting the concentration of nitrogen oxides (NOx) contained in the exhaust gas is located downstream of the throttle valve 20 in the inlet pipe 12. The DPF device 71 is equipped with an inlet temperature sensor 31 for measuring the inlet temperature of the DOC device 30, an outlet temperature sensor 45 for measuring the outlet temperature of the DOC device 30, and an outlet temperature sensor 74 for measuring the outlet temperature of the DPF 70. The SCR device 50 is equipped with an SCR outlet temperature sensor 51 for measuring the outlet temperature of the SCR device 50. A NOx sensor 52 for detecting the concentration of nitrogen oxides contained in the exhaust gas discharged from the SCR device 50 is located in the outlet pipe 14 connected to the SCR device 50. These sensors are connected to the control device 8 via a Controller Area Network (CAN) 18 and output measurement data to the control device 8. Note that the NOx sensor 32 may also be installed at the DPF outlet. Also, a temperature sensor may be installed at the SCR inlet. Other examples of sensors include differential pressure sensors installed before and after the DPF70.

[0022] The control device 8 measures the exhaust gas temperature at the inlet side of the DOC device 30 using the inlet temperature sensor 31, and adjusts the exhaust gas temperature by controlling the valve opening of the throttle valve 20 according to the measured temperature. The control device 8 obtains the engine rotation speed Ne from the engine rotation speed detection device 6, the exhaust gas temperature Tatin at the inlet side of the DOC device 30 from the inlet temperature sensor 31, and the nitrogen oxide concentration NOxin at the inlet side of the DOC device 30 from the NOx sensor 32. In addition, the control device 8 obtains the exhaust gas temperature Tatout at the outlet side of the DOC device 30 from the outlet temperature sensor 45, the SCR outlet temperature from the SCR outlet temperature sensor 51, and the nitrogen oxide concentration NOxout at the outlet side of the SCR device 50 from the NOx sensor 52. Based on this acquired data and information such as accelerator operation by the operator, the control device 8 controls the operation of the fuel injector 7, fuel injector 72, throttle valve 20, injection nozzle 41, and pump unit 43.

[0023] [Operation device] As shown in Figure 2, the operating device 60 includes various operating devices operated by the operator, such as an accelerator 61, a shift lever 62, a parking brake 63, a work equipment lever 64, a work equipment lock switch 65, and a travel lock switch 66. The operating device 60 also includes brakes, steering, etc. However, depending on the specifications of the work vehicle 1, some of the operating devices shown in Figure 2 may be omitted. The accelerator 61 is a device that controls the rotational speed (rotational velocity) (or acceleration) of the engine 2, and has the form of an accelerator pedal, accelerator lever, etc. In this embodiment, the amount of operation of the accelerator 61 is called the accelerator opening. In this embodiment, an accelerator opening of 0% is when the amount of operation is zero. The shift lever 62 is a device that controls the speed gear of the transmission. The shift lever 62 sets the transmission to neutral (hereinafter also abbreviated as "N"), forward, reverse, etc. The parking brake 63 is an operating device that switches the parking brake provided by the work vehicle 1 to an activated state or an deactivated state. The implement lever 64 is a device for operating the implement mounted on the work vehicle 1. The implement lever 64 has a mechanism that automatically returns to the neutral position when the operator releases their hand, and outputs a signal corresponding to the amount of tilt of the lever forward / backward or forward / backward / left / right from the neutral position, and the operation of various actuators is controlled by the vehicle controller 73 (or implement controller not shown) according to that signal. When the implement lock switch 65 is operated to the locked position, the operation of the implement stops. When the travel lock switch 66 is operated to the locked position, the travel device of the work vehicle 1 stops.

[0024] [Vehicle Controller] The vehicle controller 73 controls various parts of the work vehicle 1 by receiving signals from the operating device 60 indicating the operating status (on state, off state, amount of operation, etc.) of each operating device, and by sending and receiving predetermined data with other controllers (not shown), such as the control device 8. In this embodiment, the vehicle controller 73 transmits to the control device 8 data indicating the operating status of the accelerator 61, shift lever 62, parking brake 63, work equipment lever 64, work equipment lock switch 65, drive lock switch 66, etc., or the results of determining the vehicle safety condition described later (hereinafter, these data are collectively referred to as "vehicle data").

[0025] [Control device] Next, the configuration of the control device 8 will be described. As shown in Figure 3, the control device 8 includes a sensor data acquisition unit 81, a vehicle data acquisition unit 82, a temperature rise control execution unit 83, a notification instruction unit 84, and an engine speed increase control execution unit 85.

[0026] [Sensor data acquisition unit] The sensor data acquisition unit 81 repeatedly acquires measurement data from each sensor, such as the engine rotation speed detection device 6, NOx sensor 32, inlet temperature sensor 31, outlet temperature sensor 45, and NOx sensor 52, at predetermined intervals.

[0027] [Vehicle Data Acquisition Unit] The vehicle data acquisition unit 82 repeatedly acquires the above-mentioned vehicle data from the vehicle controller 73 at predetermined intervals.

[0028] [Temperature rise control execution unit] The temperature rise control execution unit 83 performs a control (called temperature rise control) to raise the temperature of the exhaust gas when regenerating the exhaust gas purification device 10. In temperature rise control, the temperature rise control execution unit 83 controls the valve opening of the throttle valve 20, and when the inlet temperature Tatin measured by the inlet temperature sensor 31 exceeds a set temperature (for example, 250°C), it controls, for example, the fuel injection device 72 to supply dosing fuel. The set temperature is the temperature at which the DOC device 30 can be activated. The dosing fuel is supplied to the DOC device 30 together with the exhaust gas and generates heat through a chemical reaction with the oxidation catalyst of the DOC device 30. Therefore, the temperature of the exhaust gas, which has risen due to the control of the valve opening of the throttle valve 20, rises further as it flows through the DOC device 30. That is, the outlet temperature Tatout of the exhaust gas measured by the outlet temperature sensor 45 becomes even higher than the inlet temperature Tatin.

[0029] In this embodiment, the temperature rise control includes automatic regeneration control and stationary manual regeneration control. Automatic regeneration control is a control that automatically executes temperature rise control when the temperature rise control execution unit 83 determines that regeneration is necessary. Stationary manual regeneration control is a control that, for example, if automatic regeneration control is not completed within a predetermined time, stops the normal operation of the work vehicle 1 and executes temperature rise control with the permission of the operator. In stationary manual regeneration control, the control device 8 (notification instruction unit 84) first uses the monitor 9 to output to the operator that it is possible to perform stationary manual regeneration and to request that it be performed. In response, when the operator uses the monitor 9 to instruct the control device 8 to perform stationary manual regeneration, the control device 8 fixes the engine speed to a certain speed, raises the exhaust temperature, and removes PM or urea deposits accumulated in the DPF and SCR, and releases HC and sulfur adsorbed on the DPF and SCR. In this embodiment, the operation of the work vehicle 1 while temperature rise control is being performed is called regeneration operation. Specific examples of temperature rise control will be described later.

[0030] [Notification instruction section] The notification instruction unit 84 notifies the operator by outputting the determination result from the monitor 9 when the temperature rise control execution unit 83 determines that it is necessary to perform stationary manual regeneration control while automatic regeneration control is being performed. The monitor 9 notifies the operator that it is necessary to perform stationary manual regeneration control by flashing the notification unit 91 or sounding a buzzer. The notification from the monitor 9 allows the operator to understand that it is difficult to complete the regeneration process by automatic regeneration temperature rise control and that it is necessary to perform stationary manual regeneration. Therefore, when the operator presses the switch 92 on the monitor 9 in response to the notification from the monitor 9 to instruct the execution of stationary manual regeneration, the temperature rise control execution unit 83 performs stationary manual regeneration.

[0031] Furthermore, if the operator does not instruct the stationary manual regeneration to be performed within the fourth determination time T14 (for example, 30 minutes) after the first notification (hereinafter referred to as the stationary manual regeneration control request L01), the notification instruction unit 84 outputs a second notification, the stationary manual regeneration control request L03. In response to the stationary manual regeneration control request L03, the monitor 9 increases the flashing speed of the notification unit 91 or increases the volume of an alert sound such as a buzzer to notify the operator again to perform the stationary manual regeneration.

[0032] [Engine speed increase control execution unit] The engine speed increase control execution unit 85 executes control to increase the target value of the engine 2's idling speed from the normal speed (e.g., 600-700 rpm) to a predetermined value (e.g., 1000 rpm) if the accelerator opening exceeds a predetermined opening threshold after the automatic regeneration control has started. Since the automatic regeneration control is a control that the control device 8 starts automatically, if the timing of increasing the idling speed setting is matched to the start timing of the automatic regeneration control, the operator may feel uncomfortable. In contrast, this discomfort can be reduced by increasing the idling speed setting in accordance with the timing when the operator operates the accelerator 61.

[0033] [Temperature control] Next, the temperature rise control in this embodiment will be described with reference to Figures 4 to 7. Figure 4 shows the overall flow of the temperature rise control. After the work vehicle 1 is started, the control device 8 (temperature rise control execution unit 83) repeatedly determines at predetermined intervals whether or not the start conditions for automatic regeneration control have been met (step S101).

[0034] The conditions for starting automatic regeneration control are met when the elapsed time since the end of the previous regeneration operation reaches the first set time T1, or when the denitrification efficiency calculated from the measurement data of NOx sensors 32 and 52 falls below a threshold, as shown in Figure 5. Here, the first set time T1 should be set considering the estimated amount of urea deposit accumulated during long-term operation, poisoning by HC and sulfur adsorbed on the DPF and SCR, etc. Hereafter, the estimated amount of urea deposit accumulated will be described as an example. For example, the amount of urea deposit accumulated per hour differs depending on the type of work vehicle 1 and diesel engine 2, the work content (operating conditions), etc., but can be estimated by experiment or simulation. In addition, the amount of urea deposit accumulated also affects the completion time of temperature rise control. Therefore, the first set time T1 should be set considering these factors. For example, if the automatic regeneration control is set to be completed in 15 minutes, and the time required to remove the accumulated urea deposit varies depending on the type of work vehicle (e.g., 24 hours, 48 ​​hours, 72 hours, 96 hours, 120 hours), then the first setting time T1 should be set to 24 hours, 48 ​​hours, 72 hours, 96 hours, 120 hours, etc., depending on the type of work vehicle. For most work vehicles, the first setting time T1 is set within the range of approximately 24 to 120 hours. The denitrification efficiency is calculated using the nitrogen oxide concentration NOxin measured by NOx sensor 32 and the nitrogen oxide concentration NOxout measured by NOx sensor 52, using the formula (Noxin - Noxout) / Noxin × 100. In this case, automatic regeneration control is performed even before the first setting time T1 has elapsed, for example, when the denitrification efficiency falls below a threshold. Furthermore, automatic regeneration control can be performed at every first set time T1 regardless of automatic regeneration based on denitrification efficiency, or the first set time T1 can be reset when automatic regeneration based on denitrification efficiency is initiated.

[0035] If the conditions for starting automatic regeneration control are met (Step S101: Yes), the temperature rise control execution unit 83 starts automatic regeneration control (Step S102). Details of automatic regeneration control will be described later. Next, the temperature rise control execution unit 83 determines whether the conditions for ending automatic regeneration control have been met (Step S103). If the conditions for ending automatic regeneration control are met (Step S103: Yes), the temperature rise control execution unit 83 terminates automatic regeneration control (Step S104) and ends the temperature rise control.

[0036] As shown in Figure 5, the automatic regeneration control termination condition is met when the time during which the DOC outlet temperature Tatout, measured by the outlet temperature sensor 45, is equal to or greater than the regeneration determination temperature θ1 (e.g., 450°C) is accumulated to obtain the first accumulated time (regeneration time), and this first accumulated time is equal to or greater than the first determination time T11 (e.g., 15 minutes). The regeneration determination temperature θ1 is set based on the regeneration target temperature θ2. The regeneration target temperature θ2 is a target value for the outlet temperature Tatout set to recover from performance degradation due to the removal of urea deposits and poisoning by HC and sulfur adsorbed on the DPF and SCR during long-term operation. Hereafter, the estimated amount of urea deposit will be described as an example. The control device 8 raises the outlet temperature Tatout mainly by increasing the supply amount of dosing fuel when the outlet temperature Tatout is lower than the regeneration target temperature θ2, and lowers the outlet temperature Tatout mainly by decreasing the supply amount of dosing fuel when the outlet temperature Tatout is higher than the regeneration target temperature θ2. Therefore, during the regeneration process to remove urea deposits, the outlet temperature Tatout fluctuates around the regeneration target temperature θ2. To determine that the regeneration process is in progress, with the outlet temperature Tatout fluctuating around the regeneration target temperature θ2, a regeneration determination temperature θ1 is set that is a predetermined temperature lower than the regeneration target temperature θ2. In this embodiment, the regeneration target temperature θ2 is set to 500°C as an example, and the predetermined temperature is set to -50°C, so the regeneration determination temperature θ1 is set to 450°C. This regeneration determination temperature θ1 is set so as not to fall below the lower limit of the temperature range in which urea deposits can be removed.

[0037] The first determination time T11 is set according to the first setting time T1. The first determination time T11 is the time required to remove the urea deposit by temperature control. Therefore, it is affected by the amount of urea deposit that has accumulated. The amount of urea deposit that has accumulated is affected by the time interval in which the temperature control is performed, i.e., the first setting time T1. Therefore, the first determination time T11 should be set according to the first setting time T1. In this embodiment, since the first setting time T1 is 48 hours as an example, the first determination time T11 is set to 15 minutes. If the first setting time T1 is longer than 48 hours, it is preferable to set the first determination time T11 to be longer as well, and if the first setting time T1 is shorter than 48 hours, the first determination time T11 can be set to be shorter as well. Therefore, the first determination time T11 should be set according to the first setting time T1, for example, in the range of 10 minutes to 60 minutes.

[0038] If the automatic regeneration control termination condition is not met (step S103: No), the temperature rise control execution unit 83 determines whether or not the first condition for stationary manual regeneration control has been met (step S105).

[0039] The first condition for stationary manual regeneration control is met, as shown in Figure 5, when, during the execution of automatic regeneration control, the first accumulated time (regeneration time), which is the time during which the measured temperature of the outlet temperature sensor 45 (outlet temperature Tatout) is equal to or greater than the regeneration determination temperature θ1, is less than the first determination time T11, and the elapsed time from the start of the regeneration process is equal to or greater than the second determination time T12 (e.g., 120 minutes). When this first condition for stationary manual regeneration control is met, the temperature rise control execution unit 83 determines that the conditions for notifying the operator that stationary manual regeneration is necessary have been met. Note that the first condition for stationary manual regeneration control is not limited to this example. For example, the amount of PM accumulation in the DPF can be estimated from the differential pressure sensor values ​​before and after the DPF (not shown), and if that estimated value is greater than or equal to a predetermined threshold, this can be included as an OR condition for the first condition for stationary manual regeneration control.

[0040] The first judgment time T11 is, as mentioned above, the time when the automatic regeneration control is completed. The second judgment time T12 is set to the time when work by the work vehicle 1 is permitted to continue while the automatic regeneration control is running. If the second judgment time T12 has elapsed without the automatic regeneration control being completed, a notification prompting the operator to perform stationary manual regeneration will be issued. Work cannot be continued by the work vehicle 1 during stationary manual regeneration. For this reason, the second judgment time T12 is set as a grace period during which the operator can continue work before the notification is issued. Therefore, if it is acceptable to set a shorter grace period, the second judgment time T12 may be shortened to, for example, 60 to 90 minutes. Also, if it is desirable to set a longer grace period, the second judgment time T12 may be lengthened to, for example, 150 to 180 minutes.

[0041] For example, as shown in Figure 6, when automatic regeneration control is being performed, if the load on the diesel engine 2 is low and the ambient temperature is low (e.g., -25°C or below), for example, when the engine is stopped at idle, the exhaust gas temperature is low, and the inlet temperature Tatin measured by the inlet temperature sensor 31 may fall below the set temperature (250°C). As a result, the supply of dosing fuel, which is only performed when the inlet temperature Tatin exceeds the set temperature, is hardly performed, and the regeneration time required for the outlet temperature Tatout measured by the outlet temperature sensor 45 to exceed the regeneration judgment temperature θ1 is also shortened. Figure 6 shows an example of the time change of DOC inlet temperature Tatin, DOC outlet temperature Tatout, regeneration time, dosing fuel flow rate, and valve opening of the throttle valve 20, with the horizontal axis being the time axis.

[0042] If the first condition for the stationary manual regeneration control request is met (step S105: Yes), the notification instruction unit 84 outputs the stationary manual regeneration control request (step S106). In step S106, the notification instruction unit 84 first outputs the stationary manual regeneration control request L01, and then, if the operator does not instruct the execution of stationary manual regeneration within the fourth determination time T14 (for example, 30 minutes), it outputs the stationary manual regeneration control request L03.

[0043] If the first condition for the stationary manual regeneration control request is not met (step S105: No), or after the notification instruction unit 84 outputs the stationary manual regeneration control request (step S106), the temperature rise control execution unit 83 determines whether the second condition for the stationary manual regeneration control request has been met (step S107).

[0044] The second condition for stationary manual regeneration control is, as shown in Figure 5, that during the execution of automatic regeneration control, the regeneration time remains less than the first determination time T11 (15 minutes), and the second accumulated time, calculated by accumulating the time during which the measured temperature of the outlet temperature sensor 45 (outlet temperature Tatout) is less than the regeneration determination temperature θ1 while dosing fuel is being supplied (i.e., while the inlet temperature Tatin is at or above the set temperature (250°C)), becomes 60 minutes or more or more than the third determination time T13 (for example, 60 minutes). If this second condition for stationary manual regeneration control is met, the temperature rise control execution unit 83 also determines that the conditions for executing stationary manual regeneration have been met.

[0045] The third determination time T13 is set as a grace period during which the exhaust gas temperature does not rise even when dosing fuel is supplied, and the regeneration process is not functioning properly. If the second condition of the stationary manual regeneration control requirement is met, it is possible that the DOC device 30 is not functioning properly, or that the operator is performing special operations such as repeatedly starting and stopping the work machine in a short period of time. For this reason, it is preferable to determine that the second condition of the stationary manual regeneration control requirement is met in a shorter time than the second determination time T12 of the first condition of the stationary manual regeneration control requirement. Accordingly, the third determination time T13 is set to be shorter than the second determination time T12, specifically half the time. The time of this third determination time T13 may also be adjusted to match the second determination time T12. For example, if the second determination time T12 is set to 90 minutes, the third determination time T13 may be set to about 40 to 60 minutes. If the second determination time T12 is set to 150 minutes, the third determination time T13 may be set to about 60 to 80 minutes.

[0046] For example, as shown in Figure 7, when automatic regeneration control is being performed, depending on how the work vehicle 1 is used, even if dosing fuel is supplied, the measured temperature of the outlet temperature sensor 45 (outlet temperature Tatout) may not rise to or above the regeneration determination temperature θ1, and the second accumulated time, which is the accumulated time when the outlet temperature Tatout is below the regeneration determination temperature θ1, may become the third determination time T13 or more. The second accumulated time is the sum of the times indicated by arrows A1 to A6 in Figure 7. Note that the first accumulated time (regeneration time) in Figure 7 is the regeneration time during which the outlet temperature Tatout is above the regeneration determination temperature θ1, just like the first condition for stationary manual regeneration control request. When this second condition for stationary manual regeneration control request is met, the state in which the automatic regeneration control termination condition is not met continues even if dosing fuel is supplied, so it can be determined that stationary manual regeneration is required earlier than the first condition for stationary manual regeneration control request. Figure 7 shows examples of the time changes of the DOC inlet temperature Tatin, DOC outlet temperature Tatout, regeneration time, dosing fuel flow rate, and valve opening of the throttle valve 20, with the horizontal axis representing time.

[0047] If the second condition for the stationary manual regeneration control request is met (step S107: Yes), the notification instruction unit 84 outputs the stationary manual regeneration control request (step S108). In step S108, the notification instruction unit 84 first outputs the stationary manual regeneration control request L01, and then, if the operator does not instruct the execution of stationary manual regeneration within the fourth determination time T14 (for example, 30 minutes), it outputs the stationary manual regeneration control request L03. Next, the temperature rise control execution unit 83 terminates the automatic regeneration control (step S109).

[0048] If it is determined that the first condition for the stationary manual regeneration control request is met (step S105: Yes), the temperature rise control execution unit 83 continues to execute the automatic regeneration control. Therefore, the automatic regeneration control process will continue even after notification by the notification instruction unit 84. If the regeneration time reaches the first determination time T11 (15 minutes) and the regeneration process by automatic regeneration control is completed before the execution of stationary manual regeneration begins (step S103: Yes), the notification instruction unit 84 stops outputting the stationary manual regeneration control request L01 or L03 in step S104 and terminates the notification on the monitor 9. On the other hand, if it is determined that the second condition for the stationary manual regeneration control request is met (step S107: Yes), the temperature rise control execution unit 83 stops executing the automatic regeneration control (step S109). Therefore, the notification by the notification instruction unit 84 will continue unless the operator performs the stationary manual regeneration operation.

[0049] If the second condition for the stationary manual regeneration control request is not met (step S107: No), or after the temperature rise control execution unit 83 has finished executing the automatic regeneration control (step S109), the temperature rise control execution unit 83 determines whether or not the stationary manual regeneration control start condition has been met (step S110).

[0050] The conditions for starting stationary manual regeneration control are met when the stationary manual regeneration switch 92 is pressed by the operator, as shown in Figure 5, and the work vehicle is in a state where stationary manual regeneration can be performed. Here, a state in which stationary manual regeneration can be performed is, for example, when the parking brake is engaged, the accelerator is in the off position, and the work equipment lever is in the neutral position, in which case the work vehicle is stopped and not operating.

[0051] If the conditions for starting stationary manual regeneration control are met (step S110: Yes), the temperature rise control execution unit 83 terminates the automatic regeneration control (step S111) and starts stationary manual regeneration control (step S112). If the automatic regeneration control has already ended in step S109, the temperature rise control execution unit 83 does nothing in step S111. Next, it is determined whether or not the conditions for ending stationary manual regeneration control have been met (step S113). If the conditions for ending stationary manual regeneration control are met (step S113: Yes), the temperature rise control execution unit 83 terminates the stationary manual regeneration control (step S114) and ends the temperature rise control.

[0052] The temperature rise control execution unit 83 performs stationary manual regeneration control, for example, as follows: The temperature rise control execution unit 83 obtains the set valve opening degree ETVffo, which is specified by the engine rotational speed Ne and target torque (or fuel injection amount Qf), from the map for stationary manual regeneration, and controls the valve opening of the throttle valve 20 so that it becomes the set valve opening degree ETVffo. Compared to automatic regeneration control, stationary manual regeneration controls the valve opening of the throttle valve 20 and the amount of dosing fuel supplied so that the exhaust gas temperature is more likely to rise, thus efficiently recovering from performance degradation of the DPF and SCR. Similar to automatic regeneration control, this stationary manual regeneration control automatically terminates when the first accumulated time during which the outlet temperature Tatout is equal to or greater than the regeneration judgment temperature θ1 becomes equal to or greater than the first judgment time T11.

[0053] In the temperature rise control shown in Figure 4, the determination process in step S103 is not executed after step S109 if the automatic regeneration control is completed. Also, the determination process in step S105 is not executed after step S105 if the second condition for the stationary manual regeneration control request is met in step S107.

[0054] [Automatic Playback Control] Next, the automatic regeneration control in this embodiment will be described with reference to Figures 8 to 14. The automatic regeneration control process shown in Figure 8 is repeatedly executed at a predetermined cycle from the start of the automatic regeneration control (step S102) until it ends (step S104 or step S111) in the temperature rise control described with reference to Figure 4.

[0055] When the process shown in Figure 8 is started, the temperature rise control execution unit 83 first determines whether or not the vehicle safety condition is met (step S201). In this embodiment, the vehicle safety condition means a state in which the work vehicle 1 is not in operation (for example, a state in which the engine 2 is running at low idle and there is a low probability that the work vehicle 1 will immediately perform an action that increases the output torque from that state). In this embodiment, operation means operating the work vehicle 1, excluding the operation of running the engine 2 in an idling state.

[0056] Figures 9 to 11 show examples of vehicle safety condition conditions. In the example shown in Figure 9, the vehicle safety condition condition (Example 1) is that condition (1) is met and condition (2-1) is met. Condition (1) is that the accelerator opening is below the accelerator opening threshold for determining safety (for example, the accelerator opening is approximately 0% or 0% to 5%). Condition (2-1) is that the shift lever is in N and the parking brake is engaged. In the example shown in Figure 10, the vehicle safety condition condition (Example 2) is that condition (1) is met and condition (2-2) is met. Condition (1) is that the accelerator opening is below the accelerator opening threshold for determining safety. Condition (2-2) is that the driving lock is ON and the work equipment lock is ON. The state in which condition (2-2) is met corresponds to a state in which neither driving nor work is performed. In the example shown in Figure 11, the vehicle safety condition condition (Example 3) is that condition (1) is met and condition (2-3) is met. Condition (1) is that the accelerator opening is below the accelerator opening threshold for determining the safe state. Conditions (2-3) are that the implement lock is ON. Note that these are just examples, and conditions such as all implement levers being in the neutral position may be combined. Furthermore, the vehicle safety state conditions can be made different depending on the type and specifications of the work vehicle 1. For example, the vehicle safety state condition (Example 1) can be used for vehicles such as wheel loaders, dump trucks, or passenger cars. The vehicle safety state condition (Example 2) can be used for vehicles such as bulldozers that operate implements while moving. The vehicle safety state condition (Example 3) can be used for vehicles such as hydraulic excavators that operate implements with little to no movement.

[0057] If the vehicle safety condition is not met (Step S201: No), the temperature rise control execution unit 83 determines the ETV opening (throttle valve opening) based on the ETV opening MAP1 (throttle valve opening map 1) for when the vehicle safety condition is not met (Step S202). If the vehicle safety condition is met (Step S201: Yes), the temperature rise control execution unit 83 determines the ETV opening (throttle valve opening) based on the ETV opening MAP2 (throttle valve opening map 2) for when the vehicle safety condition is met (Step S203). Note that ETV opening MAP1 is one component of the first map related to this disclosure, and ETV opening MAP2 is one component of the second map related to this disclosure.

[0058] Figure 12 shows an example configuration of ETV opening MAP1, and Figure 13 shows an example configuration of ETV opening MAP2. Both ETV opening MAP1 shown in Figure 12 and ETV opening MAP2 shown in Figure 13 are maps that determine the valve opening using engine speed and torque as elements. ETV opening MAP1 shown in Figure 12 differs in that the upper limit of the ETV opening is 86%, while ETV opening MAP2 shown in Figure 13 differs in that the upper limit of the ETV opening is 95%. Furthermore, ETV opening MAP2 shown in Figure 13 is set so that the valve opening is larger than that of ETV opening MAP1 shown in Figure 12 in the region where the torque is less than 400. Also, ETV opening MAP2 shown in Figure 13 is set so that the valve opening is larger than that of ETV opening MAP1 shown in Figure 12 in the region where the torque is less than 1200 rpm. In this case, the ETV opening MAP2 shown in Figure 13 is set so that in the region where torque is close to zero and the rotational speed is in the idling speed range (from low idle to idle-up state), the valve opening is further restricted than the valve opening of ETV opening MAP1.

[0059] Next, the temperature rise control execution unit 83 determines whether the DOC inlet temperature is greater than a predetermined temperature threshold (for example, 250°C, which is the temperature at which the DOC device 30 is activated) (step S204). If the DOC inlet temperature is not greater than the predetermined temperature threshold (step S204: No), the temperature rise control execution unit 83 determines the ETV opening by feedback control with the DOC inlet temperature set to a target value (for example, 250°C) (step S205). In this case, if the temperature rise control execution unit 83 selects the ETV opening MAP2 (second map) in step S205, and the DOC inlet temperature is below the predetermined threshold, it may also determine the valve opening beyond the upper limit value defined in the ETV opening MAP2 (second map) so as to reduce the deviation between the DOC inlet temperature and the predetermined target value.

[0060] Next, the temperature rise control execution unit 83 controls the ETV opening based on the ETV opening determined in step S202, S203, or S205 (step S206). Next, if the DOC inlet temperature is greater than a predetermined temperature threshold (for example, 250°C, which is the temperature at which the DOC device 30 is activated) (step S207: Yes), the temperature rise control execution unit 83 starts fuel injection control for automatic regeneration control, and if the DOC inlet temperature is less than or equal to the predetermined temperature threshold (step S207: No), the fuel injection control for automatic regeneration control ends. Here, the fuel injection control for automatic regeneration control is the control of fuel dosing by the fuel injection device 72, etc., and is a control performed in a repetitive process that is executed separately from the process shown in Figure 8, for example, and the amount of fuel injected is controlled using coefficients and maps for automatic regeneration control from the inlet temperature measured by the inlet temperature sensor 31 and the outlet temperature measured by the outlet temperature sensor 45. Note that in steps S208 and S209, no processing is performed if the process has already started or finished.

[0061] Next, the engine speed increase control execution unit 85 determines whether the accelerator opening is greater than a predetermined opening threshold (step S210), and if the accelerator opening is greater than the predetermined opening threshold, it sets the idling speed for automatic regeneration control (step S211). Once the idling speed is set for automatic regeneration control, it is not changed until the automatic regeneration control is completed. The idling speed for automatic regeneration control is, for example, a speed set higher than the normal speed by a predetermined value or a predetermined percentage.

[0062] Figure 14 shows an example of the operation of the automatic regeneration control based on the above process. Figure 14 shows an example of the time change of the DOC inlet temperature Tatin, DOC outlet temperature Tatout, regeneration time, dosing fuel flow rate, and throttle valve 20 opening degree, with the horizontal axis being the time axis. Figure 14 is an example of operation when the vehicle safety condition is met. Also, the ETV opening degree MAP2 is the example shown in Figure 13. In the example shown in Figure 14, immediately after the automatic regeneration control is started, the throttle valve opening degree is 95%, and thereafter the throttle valve opening degree rises from 95% until the DOC inlet temperature reaches 250°C, and at time t1 when the DOC inlet temperature exceeds 250°C the throttle valve opening degree returns to 95%. At time t2 the DOC outlet temperature becomes equal to or greater than the regeneration judgment temperature θ1, the regeneration time increases, and at time t3 the automatic regeneration control is terminated.

[0063] [Effects of the Embodiment] According to this embodiment, when control is required to increase the exhaust temperature in the exhaust path, the system detects when the vehicle is not operating (for example, when the vehicle is not immediately operating during low idle operation), and only when this is detected, it further restricts the opening of the exhaust throttle valve compared to before detection. With this configuration, the control to further restrict the opening of the exhaust throttle valve is performed when the operating environment of the exhaust throttle valve is stable. Therefore, when executing the control to restrict the throttle valve 20, the temperature can be efficiently increased while avoiding deterioration of performance, etc. In other words, according to this embodiment, the opening of the exhaust throttle valve can be appropriately controlled. Furthermore, since the temperature can be efficiently increased in automatic regeneration control, the frequency of stationary manual regeneration can be reduced.

[0064] While embodiments of this invention have been described above with reference to the drawings, the specific configuration is not limited to the above embodiments, and design changes and the like are also included within the scope of the gist of this invention. For example, the ETV opening MAP1 shown in Figure 12 and the ETV opening MAP2 shown in Figure 13 may be maps that determine the valve opening using the engine speed and fuel injection amount (fuel injection amount of the fuel injection device 7) as elements. Furthermore, the control device 8 can be configured using a computer, and part or all of the program executed by the computer can be distributed via a computer-readable recording medium or communication line.

[0065] [Note] The exhaust gas purification device 10 described in the embodiment can be understood as follows.

[0066] (1) An exhaust gas purification device 10 according to a first aspect of the present disclosure includes a throttle valve 20 provided in a path 11 through which exhaust gas discharged from an engine 2 whose rotational speed is controlled according to the operation of an accelerator 61 flows, a diesel oxidation catalyst device 30 disposed downstream of the throttle valve 20, a selective reduction catalyst device 50 disposed downstream of the diesel oxidation catalyst device 30, a fuel injector 72(7) that injects fuel upstream of the diesel oxidation catalyst device 30, an inlet temperature sensor 31 that measures the inlet temperature of the diesel oxidation catalyst device 30, and the outlet of the diesel oxidation catalyst device The system includes an outlet temperature sensor 45 for measuring the inlet temperature, and a control device 8 that receives temperature data measured by the inlet temperature sensor 31 and the outlet temperature sensor 45 and controls the throttle valve 20 and the fuel injection device 72. When the control device 8 performs control to throttle the throttle valve 20, it changes the upper limit of the valve opening, where the fully closed state of the throttle valve 20 is the maximum value of the valve opening and the fully open state is the minimum value of the valve opening, based on a determination result based on the accelerator opening of the accelerator 61 and the operating state of one or more operating devices (62-66) other than the accelerator 61. According to this embodiment and the following embodiments, the opening of the exhaust throttle valve can be appropriately controlled.

[0067] (2) The exhaust gas purification device 10 according to a second aspect of the present disclosure is the exhaust gas purification device 10 of (1), wherein the control device 8 changes the upper limit of the valve opening by selecting either a first map (ETV opening MAP1) which determines the valve opening using the rotational speed and torque of the engine 2 as elements, or a second map (ETV opening MAP2) in which the upper limit of the valve opening is greater than that of the first map. According to this aspect, the opening of the exhaust throttle valve can be appropriately controlled with a simple configuration.

[0068] (3) An exhaust gas purification device 10 according to a third aspect of the present disclosure is the exhaust gas purification device 10 of (2), wherein the second map is set such that the valve opening is larger than that of the first map in the region where the torque is smaller than a predetermined value. According to this aspect, it is possible to further restrict the valve opening in a stable region where the magnitude of the torque, i.e., the magnitude of the load, is relatively small.

[0069] (4) An exhaust gas purification device 10 according to a fourth aspect of the present disclosure is the exhaust gas purification device 10 of (2) or (3), wherein the second map is set such that the valve opening is larger than that of the first map in the region where the rotational speed is smaller than a predetermined value. According to this aspect, it is possible to further restrict the valve opening in a stable region where the magnitude of the rotational speed is relatively small.

[0070] (5) An exhaust gas purification device 10 according to a fifth aspect of the present disclosure is the exhaust gas purification device 10 according to (2) to (4), wherein when the control device 8 selects the second map, when the inlet temperature is below a predetermined threshold, it controls the valve opening beyond the upper limit value defined in the second map so that the deviation between the inlet temperature and a predetermined target value becomes smaller. According to this aspect, the opening can be further narrowed. [Explanation of symbols]

[0071] 1…Work vehicle, 2…Diesel engine, 3…Turbocharger, 6…Engine speed detection device, 7…Fuel injection device, 8…Control device, 9…Monitor, 10…Exhaust gas purification device, 11…Pathway, 20…Throttle valve, 30…Diesel oxidation catalyst (DOC device), 31…Inlet temperature sensor, 32…NOx sensor, 40…Urea water injection system, 41…Injection nozzle, 42…Urea water tank, 43…Pump unit, 45…Outlet temperature sensor, 50…Selective catalytic reduction (SCR device), 52…NOx sensor 60...Operating device, 61...Accelerator, 62...Shift lever, 63...Parking brake, 64...Work equipment lever, 65...Work equipment lock switch, 66...Travel lock switch, 70...DPF, 71...DPF device, 72...Fuel injection device, 73...Vehicle controller, 74...Outlet temperature sensor, 81...Sensor data acquisition unit, 82...Vehicle data acquisition unit, 83...Temperature rise control execution unit, 84...Notification instruction unit, 85...Engine speed increase control execution unit, 91...Notification unit, 92...Switch (stationary manual regeneration switch).

Claims

1. A throttle valve is provided in the path through which exhaust gases discharged from an engine whose rotational speed is controlled according to the operation of the accelerator pedal flow, A diesel oxidation catalyst device is located downstream of the throttle valve, A selective reduction catalyst device is positioned downstream of the aforementioned diesel oxidation catalyst device, A fuel injector that injects fuel upstream of the diesel oxidation catalyst, An inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device, An outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device, A control device that receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injection device. Equipped with, The control device is When performing control to restrict the throttle valve, Based on the determination result derived from the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator, The upper limit of the valve opening is changed when the fully closed state of the throttle valve is defined as the maximum value of the valve opening and the fully open state is defined as the minimum value of the valve opening. Exhaust gas purification device.

2. The control device determines the valve opening by selecting either a first map that determines the valve opening using the engine speed and torque as elements, or a second map in which the upper limit of the valve opening is greater than that of the first map, thereby changing the upper limit of the valve opening. The exhaust gas purification device according to claim 1.

3. The second map is set such that the valve opening is larger than that of the first map in the region where the torque is smaller than a predetermined value. The exhaust gas purification device according to claim 2.

4. The second map is set such that the valve opening is larger than that of the first map in the region where the rotational speed is smaller than a predetermined value. The exhaust gas purification device according to claim 3.

5. When the second map is selected, the control device controls the valve opening beyond the upper limit defined in the second map so that the deviation between the inlet temperature and a predetermined target value becomes smaller when the inlet temperature is below a predetermined threshold. The exhaust gas purification device according to any one of claims 2 to 4.

6. A throttle valve is provided in the path through which exhaust gases discharged from an engine whose rotational speed is controlled according to the operation of the accelerator pedal flow, A diesel oxidation catalyst device is located downstream of the throttle valve, A selective reduction catalyst device is positioned downstream of the aforementioned diesel oxidation catalyst device, A fuel injector that injects fuel upstream of the diesel oxidation catalyst, An inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device, An outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device, A control device that receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injection device. A control method for an exhaust gas purification device comprising: When executing control to restrict the throttle valve, the upper limit of the valve opening is changed based on the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator, with the fully closed state of the throttle valve being the maximum value of the valve opening and the fully open state being the minimum value of the valve opening. Exhaust gas purification methods.

7. A throttle valve is provided in the path through which exhaust gases discharged from an engine whose rotational speed is controlled according to the operation of the accelerator pedal flow, A diesel oxidation catalyst device is located downstream of the throttle valve, A selective reduction catalyst device is positioned downstream of the aforementioned diesel oxidation catalyst device, A fuel injector that injects fuel upstream of the diesel oxidation catalyst, An inlet temperature sensor for measuring the inlet temperature of the diesel oxidation catalyst device, An outlet temperature sensor for measuring the outlet temperature of the diesel oxidation catalyst device, In an exhaust gas purification device equipped with, A control device that receives temperature data measured by the inlet temperature sensor and the outlet temperature sensor and controls the throttle valve and the fuel injection device. When performing control to restrict the throttle valve, Based on the determination result derived from the accelerator opening degree of the accelerator and the operating state of one or more operating devices other than the accelerator, The upper limit of the valve opening is changed when the fully closed state of the throttle valve is defined as the maximum value of the valve opening and the fully open state is defined as the minimum value of the valve opening. Control device.

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