JP5320123B2 - Work vehicle and control method of work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle for promoting the combustion of particulates accumulated on a filter, and to provide a method for controlling the same. <P>SOLUTION: In a hydraulic shovel, when amounts of the particulates accumulated are not smaller than a predetermined first threshold, an engine controller performs first regenerating control. The first regenerating control controls an engine while using a first revolving speed set by a fuel dial as a target revolving speed, and controls a fuel injection device to execute filter regenerating treatment. When the amounts of particulates accumulated are not smaller than a second threshold greater than the first threshold, the engine controller performs second regenerating control. The second regenerating control controls the engine while using a second revolving speed lower than a first revolving speed as a target revolving speed, and controls the fuel injection device to executes the filter regenerating treatment. When a traveling lever is operated during the second regenerating control, the engine controller sets the target revolving speed of the engine to be higher than the second revolving speed. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a work vehicle and a work vehicle control method.

  Some work vehicles include a filter that collects particulates (particulate matter) in exhaust gas discharged from an engine. Part of the particulates collected by this filter burns in a high-temperature atmosphere of exhaust gas, but if the exhaust gas temperature is not sufficiently high, the collected particulates will continue to accumulate on the filter. become. And when the amount of particulate deposition increases, the function of the filter may deteriorate.

  Therefore, in a conventional work vehicle, a filter regeneration process for promoting combustion of particulates accumulated on the filter by increasing the temperature of the exhaust gas is performed. For example, in the work vehicle described in Patent Document 1, the temperature of the exhaust gas is increased by suppressing the cooling of the intake air and is heated to the active temperature range of the catalyst carried on the filter. Further, in the work vehicle described in Patent Document 2, fuel is added to the exhaust gas by engine fuel injection control, and the temperature of the exhaust gas is increased by the reaction heat of the fuel.

JP 2008-64005 A JP 2008-75560 A

  However, even when the filter regeneration process as described above is performed, the amount of particulate deposition may continue to increase. According to the research of the inventors of the present application, even if the filter regeneration process as described above is performed depending on the state of the output torque and the rotational speed of the engine, the combustion of the particulate does not proceed sufficiently, and the particulate is accumulated. It turns out that there is a case to continue. For example, when the work vehicle is operated in a state where the output torque of the engine is small and the engine speed is high, even if the filter regeneration process is performed, the combustion of the particulates does not proceed sufficiently. When the output torque of the engine is small, the temperature of the exhaust gas is not sufficiently high, and when the engine speed is high, the flow rate of the exhaust gas from the engine becomes high and the temperature of the exhaust gas is difficult to rise. Because it becomes. On the other hand, it was found that even when the engine output torque is small, the combustion of the particulates is easy to proceed if the engine speed is low.

  The present invention is based on the above findings, and it is an object of the present invention to provide a work vehicle that can promote combustion of particulates accumulated on a filter and a control method thereof.

  A work vehicle according to a first aspect of the present invention includes an engine, a hydraulic pump, a work implement, a filter, a filter regeneration unit, a deposition amount detection unit, an operation unit, a rotation speed setting unit, and a control unit. . The hydraulic pump is driven by the engine. The work machine is driven by hydraulic oil discharged from a hydraulic pump. The filter collects particulates in the exhaust gas from the engine. The filter regeneration unit performs a filter regeneration process for burning the particulates collected by the filter by increasing the temperature of the exhaust gas. The accumulation amount detection unit detects the accumulation amount of particulates on the filter. The operation unit is operated to control the operation of the work machine or the traveling of the vehicle. The engine speed setting unit is operated to set a target engine speed. The control unit performs the first regeneration control when the particulate accumulation amount is equal to or greater than a predetermined first threshold value. The first regeneration control is control for controlling the engine using the first rotational speed set by the rotational speed setting unit as a target rotational speed, and causing the filter regeneration unit to execute the filter regeneration process. In addition, the control unit performs the second regeneration control when the particulate accumulation amount is equal to or greater than the second threshold value that is greater than the first threshold value. The second regeneration control is control for controlling the engine with a second rotational speed smaller than the first rotational speed as a target rotational speed, and causing the filter regeneration unit to execute a filter regeneration process. Then, when the operation unit is operated during the second regeneration control, the control unit increases the target engine speed from the second engine speed.

A work vehicle control method according to a second invention includes an engine, a hydraulic pump, a work implement, a filter, a filter regeneration unit, a deposition amount detection unit, an operation unit, and a rotation speed setting unit. A vehicle control method. The hydraulic pump is driven by the engine. The work machine is driven by hydraulic oil discharged from a hydraulic pump. The filter collects particulates in the exhaust gas from the engine. The filter regeneration unit performs a filter regeneration process for burning the particulates collected by the filter by increasing the temperature of the exhaust gas. The accumulation amount detection unit detects the accumulation amount of particulates on the filter. The operation unit is operated to control the operation of the work machine or the traveling of the vehicle. The engine speed setting unit is operated to set a target engine speed. The control method includes the following steps.
When the particulate accumulation amount exceeds a predetermined first threshold, the engine is controlled with the first rotation speed set by the rotation speed setting unit as the target rotation speed, and the filter regeneration process is performed on the filter regeneration unit. Performing the first regeneration control to be executed;
When the accumulated amount of particulates is equal to or greater than a second threshold value that is greater than the first threshold value, the engine is controlled with the second rotation number that is smaller than the first rotation number as the target rotation number, and the filter regeneration unit performs filter regeneration processing. Performing the second regeneration control to execute.
A step of increasing the target engine speed from the second engine speed when the operation unit is operated during the second regeneration control.

  In the work vehicle and the work vehicle control method according to the present invention, the filter regeneration unit performs the filter regeneration process when the particulate accumulation amount is equal to or greater than a predetermined first threshold value. Further, the engine is controlled with the first rotation speed set by the rotation speed setting unit as the target rotation speed. At this time, the output torque and the rotational speed of the engine are not in the region where the particulate combustion does not sufficiently proceed even if the filter regeneration process is performed as described above (hereinafter referred to as “normally unreproducible region”). When the work vehicle is in operation in an area (hereinafter referred to as “normally reproducible area”), the amount of particulate accumulation is reduced by executing the filter regeneration process.

  On the other hand, when the engine output torque and the rotational speed are in a region where normal regeneration is not possible and the work vehicle is being operated, the amount of particulate accumulation continues to increase even when the filter regeneration process is executed. When the particulate accumulation amount is equal to or greater than the second threshold value, the engine is controlled with the second rotational speed smaller than the first rotational speed as the target rotational speed, and the filter regeneration unit performs the filter regeneration process. To do. As a result, even when the work vehicle is being operated in a state where the engine output torque and the rotational speed are in a range where the engine cannot be normally regenerated, the engine rotational speed is forcibly reduced to accumulate on the filter. The burning of the particulates can be promoted.

  The engine speed is reduced when the particulate accumulation amount is equal to or greater than the second threshold. Therefore, the decrease in the engine speed is performed when the particulates cannot be sufficiently burned only by the filter regeneration process, and is not performed when the particulates can be sufficiently burned only by the filter regeneration process. For this reason, it can suppress that work efficiency falls.

  Furthermore, when the operation unit is operated in a state where the engine speed is decreased by the second regeneration control, the target engine speed of the engine increases from the second speed. Thereby, when it is necessary to run the vehicle or operate the work implement, the engine speed can be temporarily increased. Thereby, it can suppress that driving | running | working of a vehicle or operation of a working machine cannot be performed appropriately at the time of emergency.

  In the present invention, combustion of particulates deposited on the filter can be promoted. In addition, a decrease in work efficiency can be suppressed. Furthermore, it is possible to prevent the vehicle from running or operating the work machine from being appropriately performed in an emergency.

External view of a hydraulic excavator. Schematic which shows the structure of the hydraulic system with which a hydraulic excavator is provided. The figure which shows the engine output torque characteristic and pump absorption torque characteristic of a hydraulic shovel. The block diagram which shows the structure of the exhaust-gas purification | cleaning part with which a hydraulic excavator is provided. The flowchart which shows the control method of a hydraulic shovel. The flowchart which shows the control method of a hydraulic shovel. The graph which shows the normal reproduction impossible area | region and normal reproduction | regeneration possible area | region in an engine output torque characteristic.

<Appearance configuration>
A hydraulic excavator 1 according to an embodiment of the present invention is shown in FIG. The hydraulic excavator 1 includes a traveling body 2, a revolving body 3, and a work implement 4.

  The traveling body 2 includes a pair of traveling devices 11 and 12. Each traveling device 11, 12 has crawler belts 13, 14 and a traveling motor (not shown). The crawler belts 13, 14 are driven by the traveling motor to cause the hydraulic excavator 1 to travel.

  The swivel body 3 is placed on the traveling body 2. The turning body 3 is turned on the traveling body 2 by a turning motor (not shown). A cab 15 is provided at the front left side position of the revolving structure 3.

  The work machine 4 is attached to the front center position of the revolving structure 3 and includes a boom 21, an arm 22, and a bucket 23. A base end portion of the boom 21 is rotatably connected to the swing body 3. Further, the distal end portion of the boom 21 is rotatably connected to the proximal end portion of the arm 22. The distal end portion of the arm 22 is rotatably connected to the bucket 23. In addition, hydraulic cylinders (boom cylinder 24, arm cylinder 25, and bucket cylinder 26) are arranged so as to correspond to boom 21, arm 22, and bucket 23, respectively. When these hydraulic cylinders 24 to 26 are driven, the work machine 4 is driven, and work such as excavation is performed.

<Configuration of hydraulic system>
Next, a configuration of a hydraulic system provided in the hydraulic excavator 1 is shown in FIG. In this hydraulic system, a hydraulic pump 31 is driven by an engine 32, and hydraulic oil discharged from the hydraulic pump 31 is supplied via an operation valve 33 to a boom cylinder 24, an arm cylinder 25, a bucket cylinder 26, a travel motor, a swing motor, and the like. The hydraulic actuator is supplied and discharged. By controlling the supply and discharge of the hydraulic pressure to the hydraulic actuator, the operation of the work machine 4, the turning of the turning body 3, and the running operation of the traveling body 2 are controlled.

  The engine 32 is a diesel engine, and the output of the engine 32 is controlled by adjusting the fuel injection amount from the fuel injection device 34. The fuel injection amount is adjusted by the fuel injection device 34 being controlled by the engine controller 35. The actual rotational speed of the engine 32 is detected by the rotational speed sensor 36, and the detection signal is input to the engine controller 35 and the pump controller 37, respectively.

  The hydraulic pump 31 is driven by the engine 32 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 31 is supplied to the hydraulic actuator via the operation valve 33 described later. Further, the hydraulic oil discharged from the hydraulic pump 31 is reduced to a constant pressure by the self-pressure reducing valve 38 and supplied for pilots of various valves.

  The hydraulic pump 31 is a variable displacement hydraulic pump capable of controlling the discharge capacity by controlling the tilt angle of the swash plate 41. A servo piston (not shown) is connected to the swash plate 41, and the tilt angle of the swash plate 41 is controlled by driving the servo piston. Thereby, the discharge capacity of the hydraulic pump 31 is controlled. The hydraulic pressure for driving the servo piston is controlled by the servo valve 42. The servo valve 42 controls the hydraulic pressure supplied to the servo piston in accordance with the pilot pressure supplied to the servo valve 42. This pilot pressure is supplied to the servo valve 42 via the PC valve 44 and the LS valve 43. Thereby, a pump absorption torque characteristic as shown in FIG. 3 is obtained (see lines PL1 and PL2).

  The LS valve 43 controls the pilot pressure to the servo valve 42 so that the differential pressure between the discharge pressure of the hydraulic pump 31 and the load pressure of the hydraulic actuator is constant.

  The PC valve 44 controls the pilot pressure to the servo valve 42 so that the absorption torque of the hydraulic pump 31 (hereinafter referred to as “pump absorption torque”) is constant. The pump absorption torque is controlled by the pilot pressure supplied from the PC-EPC valve 47 to the PC valve 44. The PC-EPC valve 47 is an electromagnetic control valve and is electrically controlled by a signal from the pump controller 37.

  The discharge pressure of the hydraulic pump 31 (hereinafter referred to as “pump pressure”) is detected by the hydraulic sensor 51, and the detection signal is input to the pump controller 37.

  The operation valve 33 is an assembly of hydraulic pilot operation type directional control valves provided corresponding to the hydraulic actuators. The operation valve 33 is controlled according to the operation of the operation device 60 described later, and controls the hydraulic pressure supplied to each hydraulic actuator.

  The operating device 60 is provided in the cab 15 and is operated by an operator to command various operations. The operation device 60 includes a fuel dial 61, a travel lever 62, a work machine lever 63, a machine monitor 64, and the like.

  The fuel dial 61 is a member operated by an operator in order to set a target rotational speed of the engine 32. When the fuel dial 61 is operated, a throttle signal corresponding to the operation amount of the fuel dial 61 is input to the engine controller 35 via the pump controller 37.

  The travel lever 62 is a member that is operated by an operator to control the travel of the excavator 1. When the travel lever 62 is operated, a pilot pressure corresponding to the operation content is supplied to the operation valve 33. Thereby, the hydraulic pressure supplied to the traveling motor is controlled, and the traveling operation of the excavator 1 is controlled. The pilot pressure corresponding to the operation content of the travel lever 62 is detected by the hydraulic sensor 52, and the detection signal is input to the pump controller 37.

  The work machine lever 63 is a member operated by an operator to control the operation of the work machine 4. When the work machine lever 63 is operated, a pilot pressure corresponding to the operation content is supplied to the operation valve 33. Thereby, the hydraulic pressure supplied to the boom cylinder 24, the arm cylinder 25, the bucket cylinder 26, and the turning motor is controlled, and the operation of the work implement 4 and the turning operation of the swing body 3 are controlled. The pilot pressure corresponding to the operation content of the work implement lever 63 is detected by the oil pressure sensor 53, and the detection signal is input to the pump controller 37.

  The machine monitor 64 receives various signals from the pump controller 37 and displays various information such as fuel amount and water temperature. In addition, the machine monitor 64 outputs a warning display regarding the regeneration process of the DPF 69 described later. The machine monitor 64 has operation buttons for inputting various settings of the excavator 1. For example, the machine monitor 64 can select a work mode. The work mode includes, for example, a mode that prioritizes high output and a mode that prioritizes fuel consumption. The control unit 30, which will be described later, selects the optimum engine torque and pump absorption torque according to the selected work mode and operating conditions. When the machine monitor 64 is operated, the operation signal is input to the pump controller 37.

  The control unit 30 includes an engine controller 35 and a pump controller 37.

  In the engine controller 35, target injection characteristics corresponding to a plurality of engine output torque characteristics are mapped and stored. The engine output torque characteristic indicates the relationship between the engine output torque and the rotational speed, and an example thereof is shown in FIG. 3 (see line EL1). The engine controller 35 selects an engine output torque characteristic according to the throttle signal from the fuel dial 61 and the set work mode, and controls the fuel injection device 34 based on the selected engine output torque characteristic.

  The pump controller 37 controls the pump absorption torque by controlling the PC-EPC valve 47. In the pump controller 37, a plurality of pump absorption torque characteristics set based on the work mode and the operation status are mapped and stored. The pump absorption torque characteristic indicates the relationship between the pump absorption torque and the engine speed. An example of pump absorption torque characteristics is shown in FIG. 3 (see lines PL1 and PL2). The pump controller 37 selects a pump absorption torque characteristic according to the set operation mode. Then, based on the selected pump absorption torque characteristic and the actual engine speed, the PC− is such that the pump absorption torque matches the engine output torque at the matching point (for example, the matching point M1 or M2 in FIG. 3). The EPC valve 47 is controlled.

<Configuration of exhaust gas purification unit 6>
Further, the hydraulic excavator 1 includes an exhaust gas purification unit 6 shown in FIG. The exhaust gas purification unit 6 is connected to the engine 32 and is a device that purifies exhaust gas from the engine 32. The exhaust gas purification unit 6 includes a first processing unit 55, a second processing unit 56, a first auxiliary processing unit 57, and a second auxiliary processing unit 58.

  The first processing unit 55 has a diesel particulate filter 69 (hereinafter, “DPF 69”) coated with an oxidation catalyst, collects particulates (particulate matter) in the exhaust gas, and in the exhaust gas. Nitric oxide is oxidized to produce nitrogen dioxide. Nitrogen dioxide is unstable in a high-temperature atmosphere such as exhaust gas, and releases oxygen to return to nitric oxide. Then, the particulates accumulated in the DPF 69 are combusted by the oxidizing power of the released oxygen. Nitric oxide and nitrogen dioxide that could not be returned to the nitric oxide are sent to the first auxiliary processing unit 57. In addition, as a material of DPF69, ceramics, such as cordierite and silicon carbide, or metals, such as stainless steel and aluminum, are used.

  A first pressure sensor 71 and a second pressure sensor 72 are provided on the upstream side and the downstream side of the first processing unit 55, respectively. The first pressure sensor 71 detects the pressure of the exhaust gas on the upstream side of the DPF 69. The second pressure sensor 72 detects the pressure of the exhaust gas on the downstream side of the DPF 69. The exhaust gas pressure detected by the first pressure sensor 71 and the second pressure sensor 72 is sent to the engine controller 35 as a detection signal.

  The first auxiliary processing unit 57 has a hydrolysis catalyst, and decomposes urea in the liquid reducing agent supplied from the liquid reducing agent pump 67 to generate ammonia. The first processing unit 55 and the first auxiliary processing unit 57 are connected by a communication pipe 65, and the liquid reducing agent is supplied to the exhaust gas passing through the communication pipe 65 from the liquid reducing agent tank 59 through the liquid reducing agent pump 67. Supplied.

  The second processing unit 56 is an SCR (Selective Catalytic Reduction) type catalytic converter, and includes a urea denitration catalyst (DeNOx catalyst) made of a base metal such as zeolite or vanadium. The urea denitration catalyst reacts ammonia obtained from urea with NOx in the exhaust gas, and decomposes and purifies NOx into nitrogen and oxygen.

  The second auxiliary processing unit 58 has an oxidation catalyst, oxidizes the ammonia remaining in the second processing unit 56, decomposes it into nitrogen and water, and renders it harmless. The exhaust gas processed in the second auxiliary processing unit 58 is discharged to the outside through the exhaust pipe 68.

  As described above, the particulates in the exhaust gas are collected in the DPF 69. The particulates deposited on the DPF 69 are burned in a high temperature atmosphere by the exhaust gas, but the particulates deposited on the DPF 69 cannot be completely burned at the temperature of the exhaust gas during normal operation. Therefore, in the hydraulic excavator 1, the engine controller 35 performs filter regeneration processing control as shown in the flowcharts of FIGS. 5 and 6 to process the particulates accumulated in the DPF 69 to regenerate the DPF 69.

  First, in the first step S1, the particulate accumulation amount M is detected. Here, the engine controller 35 calculates the differential pressure of the exhaust gas upstream and downstream of the DPF 69 based on the detection signals from the first pressure sensor 71 and the second pressure sensor 72. Based on the calculated differential pressure, the accumulation amount M of the particulate DPF 69 is calculated.

  In step S2, it is determined whether or not the accumulation amount M is equal to or greater than a predetermined first threshold value M1. If the accumulation amount M is equal to or greater than the predetermined first threshold value M1, the process proceeds to step S3.

  In step S3, it is determined whether or not the accumulation amount M is smaller than a predetermined second threshold M2. The second threshold value M2 is larger than the first threshold value M1. When the accumulation amount M is less than the second threshold value M2, the process proceeds to step S4.

  In step S4, a predetermined warning display is output to the machine monitor 64. For example, as a warning display, a warning code such as “L01” indicating the level of the accumulation amount M is displayed.

  In step S5, filter regeneration processing is executed. In the filter regeneration process, the fuel injection device 34 is controlled so that post injection is performed at a non-ignition timing later than the compression top dead center following the main injection of fuel performed in the engine 32 near the compression top dead center. . When such fuel injection is performed, unburned fuel mainly containing hydrocarbons (HC) is added to the exhaust gas by post injection, and the exhaust gas containing this unburned fuel is discharged from the engine 32. . And the temperature of exhaust gas rises by the reaction heat when the hydrocarbon in exhaust gas carries out the oxidation reaction by the catalyst carry | supported by DPF69. Thereby, the combustion of particulates in the DPF 69 is promoted, and the DPF 69 is regenerated.

  As described above, when the accumulation amount M is not less than the first threshold value M1 and less than the second threshold value M2, the first regeneration control is performed. In the first regeneration control, a level 1 warning display is displayed on the machine monitor 64, the engine 32 is controlled with the rotational speed (first rotational speed) set by the fuel dial 61 as a target rotational speed, and filter regeneration processing is performed. Is executed.

  Next, in step S6, it is determined whether or not the deposition amount M has become smaller than a predetermined third threshold value M3. The third threshold value M3 is a value equal to or less than the first threshold value M1. When the accumulation amount M becomes smaller than the third threshold value M3, the process proceeds to step S7.

  In step S7, the filter regeneration process is stopped. In step S8, the warning display is canceled.

  In step S6, if the accumulation amount M is greater than or equal to the third threshold value M3, the process returns to step S4, and the warning display and the filter regeneration process are maintained.

  In step S3 described above, when the accumulation amount M is equal to or larger than the second threshold value M2, the process proceeds to step S9 shown in FIG.

  In step S9, a predetermined warning display is output to the machine monitor 64. For example, as a warning display, a warning code such as “L02” indicating the level of the accumulation amount M is displayed.

  In step S10, the engine speed is reduced. Here, the engine controller 35 sets a rotational speed (second rotational speed) lower than the rotational speed (first rotational speed) set by the fuel dial 61 as the target rotational speed of the engine 32. Further, the engine controller 35 controls the fuel injection device 34 so as to reduce the output torque of the engine 32 than during normal operation. As a result, the engine output torque characteristics change from EL1 to EL2 in FIG. 3, and the rotational speed and output torque of the engine 32 are reduced.

  Further, in step S11, filter regeneration processing is executed. Here, the same processing as step S5 described above is performed. At this time, since the engine speed is reduced in step S10, the flow rate of the exhaust gas is reduced. For this reason, as compared with the case where the engine speed is not reduced, the temperature of the exhaust gas easily rises, and the combustion of particulates by the filter regeneration process is further promoted. Thereby, the DPF 69 is regenerated.

  As described above, when the accumulation amount M is equal to or greater than the second threshold value M2, the second regeneration control is performed. In the second regeneration control, a warning display of level 2 is displayed on the machine monitor 64, the engine is controlled with a rotational speed lower than the rotational speed set by the fuel dial 61 as a target rotational speed, and filter regeneration processing is executed. Is done.

  However, if the travel lever 62 is operated while the second regeneration control is being performed, it is determined in step S12 that the travel lever 62 has been operated, and the process proceeds to step S13.

  In step S13, the target rotational speed of the engine 32 is increased from the second rotational speed to the first rotational speed. That is, the target engine speed of the engine 32 is returned to the engine speed set by the fuel dial 61. As a result, the engine speed increases.

  If the travel lever 62 is not operated during the second regeneration control, the target rotational speed is set to the second rotational speed again in step S10, and the engine rotational speed is reduced.

  Then, in step S14, it is determined whether or not the accumulation amount M has become smaller than the third threshold value M3. When the accumulation amount M becomes smaller than the third threshold value M3, the process proceeds to step S7 in FIG. 5 and the filter regeneration process is stopped. In step S8, the warning display is canceled.

  If the accumulation amount M is greater than or equal to the third threshold value M3 in step S11, the process returns to step S9, and the warning display and the filter regeneration process are maintained.

<Features>
In the hydraulic excavator 1, when the particulate accumulation amount M is equal to or greater than the first threshold value M1, a warning display is output to the machine monitor 64 and filter regeneration processing is executed. At this time, as shown in FIG. 7, the output torque and the rotational speed of the engine 32 are the region R1 where the combustion of the particulates is sufficiently advanced only by the filter regeneration process (the hatched portion in FIG. In the case of “normally reproducible region R1”), the particulate accumulation amount M is reduced by the filter regeneration process. When the particulate accumulation amount M decreases to a value smaller than M3, the warning display and the filter regeneration process are canceled.

  In FIG. 7, broken lines T1 to T4 indicate the relationship between the output torque of the engine 32 at which the exhaust gas reaches the temperatures T1 to T4 and the rotational speed, and T1> T2> T3> T4. T4 indicates the minimum temperature of the exhaust gas necessary for promoting the combustion of particulates by the filter regeneration process described above. That is, in the normal reproducible region R1 where the exhaust gas temperature is equal to or higher than T4, the combustion of the particulates is sufficiently advanced only by the filter regeneration processing, and the region R2 where the exhaust gas temperature is lower than T4 (hereinafter, “normal regeneration impossible” In the region R2), the particulate combustion does not sufficiently progress only by the filter regeneration process.

  When the hydraulic excavator 1 is operated in a state where the output torque and the rotational speed of the engine 32 are in the normal non-regeneration region R2, even if the filter regeneration process is executed, the particulate accumulation amount M is Continue to increase. Then, the particulate accumulation amount M becomes equal to or greater than the second threshold M2.

  When the particulate accumulation amount M becomes equal to or greater than the second threshold value M2, the engine controller 35 controls the fuel injection device 34 to reduce the output torque and the rotational speed of the engine 32, and to perform filter regeneration processing. Let it run. As a result, even when the engine 32 is operating in a state where the output torque and the rotational speed of the engine 32 are in the normal regeneration impossible region R2 (see, for example, P1 in FIG. 7), By reducing the output torque and the rotational speed, it is possible to shift to a state where the output torque and the rotational speed of the engine 32 are in the normal reproducible region R1 (see, for example, P2 in FIG. 7). Then, by performing the filter regeneration process in this state, the combustion of the particulates accumulated in the DPF 69 can be promoted.

  Further, the reduction of the output torque and the rotational speed of the engine 32 as described above is performed when the particulate accumulation amount M becomes equal to or larger than the second threshold value M2, and is not performed until the second threshold value M2 is reached. . Accordingly, the output torque and the rotational speed of the engine 32 are reduced when the particulates cannot be sufficiently burned only by the filter regeneration process, and when the particulates can be sufficiently burned only by the filter regeneration process. Will not be executed. For this reason, it can suppress that work efficiency falls.

  It is not necessary to directly determine whether the output torque and the rotational speed of the engine 32 are in the normal regeneration impossible region R2 based on the output torque and the rotational speed of the engine 32, as described above. It may be determined whether the particulate deposition amount M is equal to or greater than the second threshold M2. The fact that the particulate accumulation amount M has reached the second threshold value M2 or more despite the execution of the filter regeneration process when the particulate deposition amount M has reached the first threshold value M1 or more indicates that the engine 32 This is because it means that the output torque and the rotational speed are in the normal non-reproducible region R2.

  In addition, while the second regeneration control is being performed, the engine speed is in a reduced state. However, when the travel lever 62 is operated, the engine speed returns to the original state. Thereby, when it is necessary to run the vehicle, the engine speed can be temporarily restored, and it is possible to prevent the vehicle from being able to run properly in an emergency.

<Other embodiments>
(A) In the above embodiment, a hydraulic excavator is exemplified as the work vehicle, but the present invention can also be applied to other types of work vehicles.

  (B) In the above embodiment, the fuel injection amount is controlled as the filter regeneration process, but other means may be used as long as it is a means for raising the temperature of the exhaust gas.

  (C) In the above embodiment, the particulate matter accumulation amount M is detected by the differential pressure between the upstream side and the downstream side of the DPF 69, but the particulate matter accumulation amount M may be detected by other means. .

  (D) In the above embodiment, the same third threshold value M3 is used in step S6 in FIG. 5 and step S14 in FIG. 6, but different threshold values may be used. For example, in step S6, it may be determined whether the deposition amount M is smaller than the first threshold value M1, and in step S14, it may be determined whether the deposition amount M is smaller than the second threshold value M2. In this case, if the deposition amount M is smaller than the second threshold value M2 in step S14, the process may proceed to step S4.

  (E) In the above embodiment, the warning display is displayed on the machine monitor 64, but other display means such as a warning lamp may be used. Moreover, not only a display but a warning sound, an audio | voice, etc. may be output from a speaker.

  (F) In the above embodiment, the target rotation speed of the engine 32 is returned to the first rotation speed by operating the travel lever 62. However, when the work implement lever 63 is operated, the engine 32 The target rotational speed may be returned to the first rotational speed.

  (G) In the above embodiment, when the travel lever 62 is operated, the target rotational speed of the engine 32 is returned to the first rotational speed, but the rotational speed is different from the first rotational speed higher than the second rotational speed. It may be changed to a number.

(H)
In the embodiment described above, the engine speed is reduced by changing the engine output torque characteristic when the accumulation amount M is equal to or greater than the second threshold value M2. However, only the engine speed may be reduced without changing the engine output torque characteristic.

  The present invention can promote the combustion of particulates accumulated in the filter, can suppress a decrease in work efficiency, and can prevent the vehicle from running or operating the work machine properly in an emergency. It is useful as a work vehicle and a work vehicle control method.

4 Working machine 31 Hydraulic pump 32 Engine 34 Fuel injection device (filter regeneration unit)
35 Engine controller (control unit)
61 Fuel dial (rotation speed setting part)
62 Travel lever (control unit)
63 Working machine lever (control unit)
69 DPF (filter)
71 1st pressure sensor (deposition amount detection part)
72 Second pressure sensor (deposition amount detector)

Claims (2)

Engine,
A hydraulic pump driven by the engine;
A working machine driven by hydraulic fluid discharged from the hydraulic pump;
A filter that collects particulates in the exhaust gas from the engine;
A filter regeneration unit that performs a filter regeneration process for burning particulates collected by the filter by increasing the temperature of the exhaust gas;
A deposition amount detection unit for detecting the amount of particulate deposition in the filter;
An operation unit operated to control the operation of the working machine or the traveling of the vehicle;
A rotational speed setting unit operated to set a target rotational speed of the engine;
When the accumulated amount of particulates is equal to or greater than a predetermined first threshold, the engine is controlled with the first rotation speed set by the rotation speed setting unit as a target rotation speed, and the filter regeneration unit When the first regeneration control for executing the filter regeneration process is performed and the particulate accumulation amount is equal to or greater than a second threshold value that is greater than the first threshold value, a second rotational speed that is smaller than the first rotational speed is targeted. The engine is controlled as a rotational speed, and second regeneration control is performed to cause the filter regeneration unit to execute the filter regeneration process. When the operation unit is operated during the second regeneration control, target rotation of the engine is performed. A controller for increasing the number from the second rotational speed;
Work vehicle equipped with. An engine, a hydraulic pump driven by the engine, a working machine driven by hydraulic oil discharged from the hydraulic pump, a filter for collecting particulates in exhaust gas from the engine, and the exhaust gas A filter regeneration unit that performs a filter regeneration process for burning particulates accumulated on the filter by increasing the temperature of the filter, a deposition amount detection unit that detects a particulate deposition amount on the filter, and the working machine A control method for a work vehicle comprising: an operation unit operated to control the operation of the vehicle or driving of the vehicle; and a rotation speed setting unit operated to set a target rotation speed of the engine,
When the accumulated amount of particulates is equal to or greater than a predetermined first threshold, the engine is controlled with the first rotation speed set by the rotation speed setting unit as a target rotation speed, and the filter regeneration unit Performing first regeneration control for executing filter regeneration processing;
When the accumulation amount of the particulates is equal to or greater than a second threshold value that is greater than the first threshold value, the engine is controlled with a second rotational speed that is smaller than the first rotational speed as a target rotational speed, and the filter regeneration unit Performing a second regeneration control that causes the filter regeneration process to be executed;
Increasing the target engine speed of the engine from the second engine speed when the operation unit is operated during the second regeneration control;
A method for controlling a work vehicle.

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