JP2009138689A - Exhaust emission control system for work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately regenerate a diesel particulate filter (DPF) by preventing the actual excessive accumulation of particulate matters (PM) when a PM accumulation estimate value reaches a limit value in the case of regenerating the DPF by calculating the PM accumulation estimate value. <P>SOLUTION: A controller 4 calculates the accumulation estimate value M of the PM accumulated in the filter 32 of a DPF device 34 based on the actual rotational speed of an engine 1, a command value to an electronic governor, and exhaust gas temperature, and starts normal combustion control if the PM accumulation estimate value is an accumulation limit value MO or more. When the PM accumulation estimate value M is smaller than the accumulation limit value MO, the controller reads a differential pressure ΔP between the front and rear of the filter 32. When the differential pressure therebetween becomes a differential pressure limit value ΔPO or more, the controller calculates a difference ΔM between the accumulation limit value MO and the PM accumulation limit value M. When the difference ΔM exceeds the limit value ΔMO, the controller displays on a monitor 38 the fact that the ΔM exceeds the limit value ΔMO, and starts complete combustion control by operator operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification system for a work vehicle, and in particular, in a traveling work vehicle such as a hydraulic excavator, regeneration control of particulate matter deposited on a filter for collecting particulate matter contained in exhaust gas. The present invention relates to an exhaust gas purification system for a work vehicle that burns and removes the fuel and regenerates the filter.

  Patent Documents 1 to 3 disclose a system for collecting particulate matter (PM: particulate matter: hereinafter referred to as PM as appropriate) contained in exhaust gas of a diesel engine and reducing the amount of PM discharged to the outside. Exhaust gas purification systems are known. This system arranges a filter called a particulate filter (DPF: Diesel Particulate Filter) in an exhaust system of an engine, collects PM contained in the exhaust gas by this filter, and purifies the exhaust gas.

  In addition, in the systems described in Patent Documents 1 and 2, in order to prevent clogging of the filter, information on load sensors such as a rotation speed sensor and an accelerator opening sensor is taken into the controller and the controller is preliminarily stored in the controller. The PM emission amount We discharged from the diesel engine 1 at that time is calculated from the stored PM emission amount map, and the temperature information detected by the temperature sensor provided in the DPF is taken into the controller, and the controller A PM combustion amount Wc burned by the DPF is calculated from a PM combustion amount map stored in advance. Then, by subtracting the combustion amount Wc from the discharge amount We, the PM accumulation amount Wa accumulated in the DPF is calculated and integrated. When this accumulated accumulation amount (deposition amount estimation value) Wa exceeds a predetermined amount (deposition amount limit value), the controller controls the injection nozzle to perform fuel post-injection and exhausts The temperature is forcibly increased, and PM accumulated on the filter is burned and removed to regenerate the DPF. In Patent Document 2, the PM accumulation amount (deposition amount estimation value) Wa of the DPF is calculated even during the PM combustion control (regeneration), and the PM combustion control is ended when the accumulation amount estimation value is equal to or less than the regeneration end threshold value. .

  In the system described in Patent Document 3, PM combustion control (regeneration) is terminated when a predetermined time set in a timer provided in the control circuit has elapsed.

JP 2001-280118 A Japanese Patent Laid-Open No. 5-332125 JP 56-115809 A

  However, the above prior art has the following problems.

  In the prior arts described in Patent Documents 1 and 2, when the PM accumulation amount estimated value Wa exceeds a predetermined amount (deposition amount limit value) as described above, the exhaust temperature is forcibly increased. The PM accumulated on the filter is burned and removed. In Patent Document 2, the PM accumulation amount (deposition amount estimation value) Wa of the DPF is calculated even during PM combustion control, and the PM combustion control (regeneration) is ended when the accumulation amount estimation value becomes equal to or less than the regeneration end threshold value.

  By the way, there is an error in the PM accumulation amount estimated value with respect to the PM amount actually accumulated in the DPF. During PM combustion control, the PM accumulation amount (deposition amount estimation value) Wa of the DPF is calculated and accumulated. Even if the PM combustion control (regeneration) is terminated when the amount estimated value is equal to or less than the regeneration end threshold, the actual PM remaining amount is not necessarily zero at the end of the regeneration. In Patent Document 2, since the PM amount after regeneration is reset to a predetermined initial value, when regeneration is insufficient and PM remains in the DPF, PM deposition proceeds again from that state. When the estimated deposition amount reaches the limit value, the actual PM deposition amount may already greatly exceed the limit value.

  It is also conceivable that the above PM combustion control (regeneration) is terminated by a timer as in Patent Document 3, for example. However, in this case as well, the remaining PM amount at the end of regeneration is not always zero, and as in the case described above, when the estimated accumulated amount reaches the limit value, the actual accumulated PM amount has already been reached. May significantly exceed the limit.

  In this way, if regeneration is performed in a state where the actual PM deposition amount greatly exceeds the limit value, an excessive amount of PM is combusted, so that the DPF becomes high temperature and the DPF material is melted, There is a problem that cracks occur in the DPF material due to thermal distortion due to high temperature, and the catalyst deteriorates.

  The object of the present invention is to prevent the excessive accumulation of actual PM when the estimated amount of deposition reaches the limit when the estimated amount of accumulated PM is calculated and the DPF is regenerated. An object is to provide an exhaust gas purification system for a work vehicle that can be appropriately regenerated.

  (1) In order to achieve the above object, the present invention provides a filter device that is disposed in an exhaust system of a diesel engine and includes a filter that collects particulate matter contained in exhaust gas, and fuel in the exhaust gas. The exhaust gas purification system for a work vehicle has a regenerator that raises the temperature of the exhaust gas by injecting the exhaust gas and burns and removes the particulate matter deposited on the filter. The accumulated amount estimated value of the particulate matter accumulated in the gas is calculated, and when the estimated accumulated amount exceeds a predetermined accumulated amount limit value, the regeneration device is operated by the first regeneration combustion control, and the accumulated particulate state of the filter A first regeneration control means for combusting and removing the substance, and detecting the differential pressure across the filter, and when the differential pressure across the filter exceeds a preset differential pressure limit value, Kino assumed and a second reproduction control means for determining the necessity of burning and removing the residual particulate matter of the filter based on a difference between the accumulation amount limit value and the accumulation amount estimation value.

  The operation principle of the present invention configured as described above is as follows.

  In the present invention, when the differential pressure before and after the filter exceeds a preset differential pressure limit value, combustion of the residual particulate matter (PM) of the filter is performed based on the difference between the estimated deposit amount and the limit deposit amount. Determine if removal is necessary. Here, as a limit value of the differential pressure before and after the filter (differential pressure limit value), when PM deposition proceeds from a state where the residual particulate matter amount (residual PM amount) of the filter is zero, the PM of A value related to the differential pressure before and after the filter at the time when the estimated accumulation amount reaches the accumulation amount limit value (for example, a value equal to the differential pressure before and after the filter at the time) is set. By setting the differential pressure limit value in this way, when the residual PM amount of the filter is not zero (for example, when the residual PM amount = Ma), the differential pressure before and after the filter reaches the limit earlier by the residual PM amount Ma. If the value 0 is reached and the difference between the accumulation amount limit value and the PM accumulation amount estimated value at that time is calculated, the remaining PM amount Ma can be obtained, and the necessity of combustion removal of the remaining PM of the filter is determined from the difference. be able to.

  The present invention is based on such knowledge. In addition to the first regeneration control unit, the second regeneration control unit is provided, and the differential pressure across the filter is equal to or higher than a preset differential pressure limit value. Based on the difference between the accumulated amount estimated value and the accumulated amount limit value, it is determined whether or not the remaining PM of the filter needs to be removed by combustion, so that the remaining PM of the filter that could not be removed by the first regeneration combustion control is appropriately removed by combustion. It is possible to prevent excessive accumulation of actual PM at the time when the estimated amount of accumulation reaches the limit value, and to appropriately regenerate the DPF.

  (2) In the above (1), preferably, the second regeneration control means is configured to allow the filter to remain when a difference between the accumulation amount estimated value and the accumulation amount limit value exceeds a preset accumulation amount difference limit value. It is determined that the particulate matter needs to be removed by combustion, and a process for removing the particulate matter remaining in the filter by the second regeneration combustion control having a combustion effect higher than that of the first regeneration combustion control is performed.

  As described above, when it is determined that the difference between the accumulation amount estimated value and the accumulation amount limit value exceeds the accumulation amount difference limit value and it is necessary to remove the residual particulate matter from the filter, the first regeneration combustion control is performed. However, by performing the second regeneration combustion control having a high combustion effect, the remaining PM of the filter that could not be combusted by the first regeneration combustion control can be effectively burned and removed.

  (3) In the above (2), preferably, the second regeneration control means maintains the engine speed at a predetermined value in the second regeneration combustion control, and operates the regeneration device in this state. .

  By performing the second regeneration combustion control while maintaining the engine speed at a predetermined value in this manner, the exhaust gas temperature of the engine can be raised and the remaining PM of the filter can be reliably removed by combustion.

  (4) In the above (2), the second regeneration control means may make the operation time of the regeneration device longer than the operation time of the regeneration device in the first regeneration combustion control in the second regeneration combustion control. Good.

  Thus, the remaining PM of the filter can be reliably burned and removed by making the operation time of the regenerator in the second regenerative combustion control longer than the operation time of the regenerator in the first regenerative combustion control.

  (5) In the above (2) or (3), preferably, the apparatus further includes a monitor and a regeneration control start instructing device, wherein the second regeneration control means performs residual particles of the filter by the second regeneration combustion control. As a process for burning and removing the particulate matter, the fact that the residual particulate matter of the filter needs to be burned and removed is displayed on the monitor, and then when the regeneration control start instruction device is operated, the second control Regenerative combustion control is started.

  By displaying on the monitor that it is necessary to burn and remove the residual particulate matter from the filter, the operator understands the necessity of manual regeneration, stops the work by the work vehicle, and in this state the regeneration control start instruction device Therefore, the remaining PM can be burned in a state in which the state of the vehicle body and the engine is stable and there is little disturbance, and ideal combustion removal of the remaining PM can be performed.

  (6) In the above (5), preferably, the work vehicle includes a work driven body driven by power of the engine, and first operation means for commanding an operation of the work driven body. A second operating means that is selectively operated to a first position that validates the command of the first operating means and a second position that invalidates the command of the first operating means; The regeneration control means starts the second regeneration combustion control when the second operation means is operated to the second position and the regeneration control start instruction device is operated.

  Thereby, while the second operating means is in the second position, even if the operator inadvertently operates the first operating means to operate the work driven body, the work driven body does not operate. Once the second regeneration combustion control is started, combustion control in a stable state in the filter device (DPF) without performing vehicle body operation can be performed to the end, and the remaining PM of the filter is surely burned and removed. be able to.

  (7) In the above (5), preferably, the work vehicle has third operation means for setting a target engine speed, and the second regeneration control means is controlled by the third operation means. When the target engine speed of the engine is set to low idle and the regeneration control start instruction device is operated, the second regeneration combustion control is started.

  As a result, when the second regeneration combustion control ends, the engine speed decreases to low idle, so that the operator can know the end of the second regeneration combustion control with the engine sound.

  (8) In the above (5), preferably, the work vehicle has fourth operation means for instructing operation of the work vehicle, and the second regeneration control means executes the second regeneration combustion control. When the fourth operating means is operated, the fact that the second regeneration combustion control is being performed is displayed on the monitor, and the instruction by the operation of the fourth operating means is invalidated.

  Thereby, even when the operator inadvertently operates the fourth operation means (for example, any one of the first to third operation means) during the second regeneration combustion control, the operator is in the second regeneration combustion control by the monitor display. And the second regeneration combustion control can be performed to the end without stopping.

  According to the present invention, when the estimated amount of accumulated PM is calculated and the DPF is regenerated, excessive accumulation of actual PM when the estimated amount of accumulated amount reaches the limit value is prevented. Reproduction can be performed appropriately. Further, by appropriately regenerating the DPF, it is possible to prevent the DPF from being melted and the catalyst from being deteriorated due to combustion of an excessive amount of PM, and to prevent the deterioration of the fuel consumption due to the increase in the engine back pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an overall configuration of an exhaust gas purification system for a work vehicle according to a first embodiment of the present invention.

  In FIG. 1, a work vehicle according to the present embodiment is a hydraulic excavator that is an example of a construction machine, and the hydraulic excavator includes a diesel engine (hereinafter referred to as an electronic control fuel injection control device) (hereinafter referred to as a diesel engine). 1). The target rotational speed of the engine 1 is instructed by an engine control dial 2 (third operating means; fourth operating means) provided in a cabin (operator's cab) 107 (see FIG. 3) of the hydraulic excavator. The rotational speed is detected by the rotational speed detection device 3. The command signal of the engine control dial 2 and the detection signal of the rotational speed detection device 3 are input to the controller 4, and the controller 4 sends the electronic governor 1 a to the electronic governor 1 a based on the command signal (target rotational speed) and the detection signal (actual rotational speed). A fuel injection amount command signal is output, and the electronic governor 1a injects fuel according to the command signal to control the rotational speed and torque of the engine 1. Further, as a start / stop command device for the engine 1, a key switch 5 is provided in the cabin 107, and a command signal of the key switch 5 is also input to the controller 4, and the controller 4 receives a starter (not shown) based on the command signal. ) And the electronic governor 1a, and the start and stop of the engine 1 are controlled. A driver's seat 108 is installed in the cabin 107 of the excavator, and a gate lock lever 22 (second operating means; fourth operating means) is provided on the left side of the front side of the driver's seat 108 (the entrance side of the cabin 107). It has been.

  The exhaust gas purification system of the present embodiment is provided in the work vehicle (hydraulic excavator) as described above, and is disposed in the exhaust pipe 31 constituting the exhaust system of the engine 1 and is included in the exhaust gas. A filter 32 that collects (PM) and a DPF device 34 that includes an oxidation catalyst 33 located upstream of the filter 32, a position detection device 35 that detects the operating position of the gate lock lever 22, and an upstream side of the filter 32. A differential pressure detection device 36 that detects downstream differential pressure (pressure loss of the filter 32), an exhaust temperature detection device 37 that is installed upstream of the filter and detects the temperature of exhaust gas, and a display screen 38a. Pressure detection for detecting the discharge pressure of the display device (monitor) 38, the regeneration control start switch 39 provided on the display device 38, and the main hydraulic pump 11 (see FIG. 2) A location 41, and a regeneration fuel injection device 40 which is provided between the engine 1 and the DPF device 34 of the exhaust pipe 31.

  The regeneration fuel injection device 40 constitutes a regeneration device for the filter 32 that injects fuel into the exhaust gas to raise the temperature of the exhaust gas and incinerate and remove PM (particulate matter) deposited on the filter 32. The regeneration control start switch 39 is an operating means for instructing the start of second regeneration combustion control (described later). When the regeneration control start switch 39 is operated from the OFF position to the ON position, the regeneration control start switch 39 instructs the start of the second regeneration combustion control. A command signal is output.

  The detection signals of the position detection device 35, the exhaust temperature detection device 37 and the pressure detection device 41 and the command signal of the regeneration control start switch 39 are input to the controller 4, and the controller 4 receives these signals and the above-mentioned engine control dial 2 from the engine control dial 2. Based on the command signal, the detection signal of the rotation speed detection device 3, and the command signal to the electronic governor 1a, the regeneration combustion control is calculated, and the regeneration fuel injection device 40 and the electronic governor 1a are controlled according to the calculation result. To do. Further, the controller 4 includes information indicated by various signals from the rotation speed detection device 3, the key switch 5, the position detection device 35, the differential pressure detection device 36, the exhaust gas temperature detection device 37, the regeneration control start switch 39, and the pressure detection device 41. And the calculation processing result of the regenerative combustion control of the controller 4 is sent as a display signal to the display device 38 and the information is displayed on the display screen 38a. Information displayed on the display screen 38a by the display device 38 includes information notifying whether or not second regeneration combustion control (described later) is necessary, and the operator operates the regeneration control start switch 39 based on the information to perform second regeneration control. Combustion control (described later) can be started.

  FIG. 2 is a diagram showing a hydraulic system mounted on a hydraulic excavator that is a work vehicle according to the present embodiment. The hydraulic system of the hydraulic excavator includes a variable displacement main hydraulic pump 11 and a fixed displacement pilot pump 12 driven by an engine 1, a hydraulic motor 13 driven by pressure oil discharged from the hydraulic pump 11, and hydraulic pressure. A plurality of hydraulic actuators including cylinders 14 and 15 and pilot operated flow control valves 17 to control the flow (flow rate and direction) of pressure oil supplied from the hydraulic pump 11 to the hydraulic motor 13 and the hydraulic cylinders 14 and 15. Connected to the downstream side of the pilot hydraulic pressure source 20, a pilot relief valve 21 that forms a pilot hydraulic pressure source 20, and maintains a constant pressure of the pressure oil discharged from the pilot pump 3. The gate lock lever 22 (FIG. 1) provided on the entrance side of the driver's seat 108 (FIG. 1) of the excavator An electromagnetic switching valve 23 that is ON / OFF controlled according to the open / close state and a pilot oil passage 24 downstream of the electromagnetic switching valve 23 are connected to operate the flow rate control valves 17 to 19 using the hydraulic pressure of the pilot hydraulic power source 20 as a source pressure. Remote control valves 25, 26 and 27 (first operating means; fourth operating means) for generating control pilot pressures a to f for the purpose, and main relief as safety means for defining the upper limit of the discharge pressure of the main hydraulic pump 11 And a valve 29. The remote control valves 25, 26, and 27 are built in left and right control lever units (not shown) provided on the left and right sides of the driver's seat 108. The aforementioned pressure detection device 41 is connected to the discharge line of the main hydraulic pump 11.

  FIG. 3 is a diagram illustrating an appearance of a hydraulic excavator that is an example of a construction machine on which the hydraulic system illustrated in FIG. 2 is mounted. The hydraulic excavator includes a lower traveling body 100, an upper swing body 101, and a front work machine 102. The lower traveling body 100 has left and right crawler traveling devices 103a and 103b, and is driven by left and right traveling motors 104a and 104b. The upper swing body 101 is turnably mounted on the lower traveling body 100 by the swing motor 105, and the front work machine 102 is attached to the front portion of the upper swing body 101 so as to be able to be raised and lowered. The upper swing body 101 is provided with an engine room 106 and a cabin (operating room) 107. The engine 1 is disposed in the engine room 106, and a gate lock lever 22 (on the entrance side of the driver's seat 108 (FIG. 1) in the cabin 107). FIG. 1) is provided, and control lever units (not shown) having remote control valves 25, 26, and 27 built in are arranged on the left and right sides of the driver's seat. Further, an engine control dial 2, a key switch 5, and a display device 38 are installed at appropriate positions in the cabin 107.

  The front work machine 102 has an articulated structure having a boom 111, an arm 112, and a bucket 113. The boom 111 rotates in the vertical direction by expansion and contraction of the boom cylinder 114. , And the bucket 113 is rotated up and down and back and forth by the expansion and contraction of the bucket cylinder 116.

  In FIG. 2, the hydraulic motor 13 is, for example, a turning motor 105, the hydraulic cylinder 14 is, for example, an arm cylinder 115, and the hydraulic cylinder 15 is, for example, a boom cylinder 114. The hydraulic system shown in FIG. 2 includes other hydraulic actuators and control valves corresponding to the traveling motors 104a and 104b, the bucket cylinder 116, etc., but is not shown in FIG.

  Returning to FIG. 1, the gate lock lever 22 can be selectively operated to a first position A that is a lowered position that restricts the entrance of the driver's seat 108 and a second position B that is the raised position that opens the entrance of the driver's seat 108. It is. When the gate lock lever 22 is in the first position A, the solenoid of the electromagnetic switching valve 23 is excited to switch the electromagnetic switching valve 23 from the illustrated position, and the pressure of the pilot hydraulic pressure source 20 is guided to the remote control valves 25, 26, 27. Thus, the control pilot pressures a to f can be generated by the remote control valves 25, 26 and 27, and the flow control valves 17 to 19 can be operated by the control pilot pressures a to f. When the gate lock lever 22 is raised to the second position B, the solenoid of the electromagnetic switching valve 23 is de-energized to switch the electromagnetic switching valve 23 to the position shown in the figure, and the pilot hydraulic power source 20 and the remote control valves 25, 26, Thus, the control pilot pressures a to f cannot be generated by the remote control valves 25, 26 and 27, and the operation of the flow control valves 17 to 19 by the control pilot pressures a to f is disabled. That is, when the gate lock lever 22 is raised to the second position B, the remote control valves 25, 26 and 27 (control lever unit) are locked. For switching the position of the electromagnetic switching valve 23 by the gate lock lever 22, for example, a switch (not shown) is provided between the solenoid of the electromagnetic switching valve 23 and the power source, and when the gate lock lever 22 is at the first position A, the switch is turned on. The solenoid is energized by turning it ON (closed), and when the gate lock lever 22 is operated to the second position B, the switch is turned OFF (open) to release the excitation of the solenoid.

  Further, the pressure detection device 41 detects the discharge pressure of the hydraulic pump 11 to determine whether one of the operation levers of the remote control valves 25, 26, 27 has been operated (whether the operator is trying to move the hydraulic excavator). It is to detect. That is, in the hydraulic system of FIG. 2, the flow control valves 17 to 19 are a center bypass type through which the center bypass line penetrates. When in the neutral position, the center bypass passage is fully opened and the discharge pressure of the hydraulic pump 11 is increased. When operated from the neutral position, the center bypass passage is throttled to increase the discharge pressure of the hydraulic pump. Thereby, the pressure detection device 41 can detect whether one of the operation levers of the remote control valves 25, 26, 27 is operated by detecting the discharge pressure of the hydraulic pump 11.

  FIG. 4 is a flowchart showing the calculation processing contents of the regeneration combustion control (first and second regeneration combustion control) of the controller 4.

  In FIG. 4, the controller 4 first detects a detection signal of the rotation speed detection device 3 (actual rotation speed of the engine 1), a fuel injection amount command signal output to the electronic governor 1a (command value to the electronic governor 1a), exhaust gas, and the like. A detection signal (exhaust gas temperature) of the temperature detection device 37 is read (step S100). These are parameters related to the operating status of the engine 1. Next, the controller 4 accumulates in the filter 32 of the DPF device 34 based on the actual rotational speed of the engine 1, the command value to the electronic governor and the exhaust gas temperature, which are parameters relating to the operating status of the engine 1. The PM accumulation amount estimation value Mi is calculated, and the accumulation amount estimation value Mi is integrated to calculate the accumulation amount estimation value M (step S105). The initial value of the PM accumulation amount estimation value M is, for example, zero, and the PM accumulation amount estimation value M is reset to zero at the end of this control.

  The calculation of the accumulation amount estimated value Mi is performed as follows, for example.

  The controller 4 stores in advance a PM emission amount map as shown in FIG. 5 and a PM combustion amount map as shown in FIG. Here, the PM amount discharged from the engine 1 increases as the engine speed increases, and increases as the engine load increases. Therefore, in the PM emission amount map shown in FIG. 5, the PM emission amount M1 increases as the engine speed increases, and the PM emission amount M1 increases as the electronic governor command value as engine load information increases. Is set. Further, the amount of PM combusted in the DPF device 34 increases as the exhaust gas temperature in the DPF device 34 increases. Therefore, the PM combustion amount map shown in FIG. 6 is also set so that the PM combustion amount M2 increases as the exhaust gas temperature increases. The controller 4 refers to the PM emission amount map shown in FIG. 5 with respect to the engine rotation speed (actual rotation speed) and the electronic governor command value read in step S100, and determines the PM emission amount Mi1 discharged from the engine 1 at that time. While calculating, the exhaust gas temperature read in step S100 is referred to the PM combustion amount map shown in FIG. 6, and the PM combustion amount Mi2 in the DPF device 34 at that time is calculated. Then, the PM combustion amount Mi2 is subtracted from the PM emission amount Mi1, and the PM accumulation amount estimated value Mi at that time is obtained (Mi = Mi1-Mi2).

  Next, the controller 4 determines whether or not the PM deposition amount estimated value M calculated in step S105 is smaller than a deposition amount limit value M0 set in advance as a threshold value (step S110). If M is equal to or greater than the accumulation amount limit value M0), normal combustion control (first regeneration combustion control) is started (step S115). Here, the normal combustion control is control for burning and removing PM accumulated on the filter 32 by controlling the regeneration fuel injection device 40 and injecting fuel into the exhaust pipe 31, and the accumulation amount limit value M0. Is a value set in advance by experiments or the like as a deposition amount suitable for starting normal combustion control. In this normal combustion control, by injecting fuel into the exhaust pipe 31, a part of the injected fuel is combusted and the temperature of the exhaust gas rises, and unburned fuel is supplied to the oxidation catalyst 33, and the oxidation catalyst 33 The exhaust gas temperature is further raised by the reaction heat obtained at that time, and the PM accumulated in the filter 32 is burned and removed by the high-temperature exhaust gas.

  Then, after the start of normal combustion control, it is determined whether or not the control time has elapsed for a predetermined time Ta (step S120), and when the predetermined time Ta has elapsed, the control is terminated (step S125).

  On the other hand, when the determination is Yes in step S110 (when the PM accumulation amount estimated value M is smaller than the accumulation amount limit value M0), the detection signal of the differential pressure detection device 36 (the differential pressure ΔP before and after the filter 32) is used. Reading (step S130), it is determined whether or not the front-rear differential pressure ΔP is smaller than a differential pressure limit value ΔP0 set in advance as a threshold value (step S135). If Yes, the front-rear differential pressure ΔP is the differential pressure limit value (threshold value). (If it is smaller than ΔP0), return to START and repeat the above processing (RETURN). The differential pressure limit value ΔP0 is obtained when the PM deposition amount estimated value M reaches the deposition amount limit value M0 when PM deposition proceeds from a state where the remaining PM amount of the filter 32 is zero. This value is preset as a value related to the front-rear differential pressure ΔP of the filter 32. In the present embodiment, it is preset as a value equal to the front-rear differential pressure ΔP.

  Then, when the determination in step S135 is No (when the differential pressure ΔP before and after becomes equal to or greater than the differential pressure limit value (threshold value) ΔP0), the PM accumulation amount estimated value M calculated in step S105 from the PM accumulation amount limit value M0. Is subtracted to obtain a deposition amount deviation ΔM (= M0−M) (step S140). This accumulation amount deviation ΔM is a value corresponding to the remaining PM amount of the filter 32 (described later).

  Then, it is determined whether or not the accumulation amount deviation ΔM exceeds a limit value (threshold value) ΔM0 set in advance as a threshold value (step S145), and if No (if the accumulation amount deviation ΔM is equal to or less than the limit value ΔM0), a step is performed. Proceeding to S115, the above-described normal combustion control (first regeneration combustion control) is performed. In step S145, when the determination is Yes (when the accumulation amount deviation ΔM exceeds the limit value ΔM0), the particulate matter is greater than the allowable value in the filter 32 even though the normal combustion control is performed. In the display device (monitor) 38, the controller 4 indicates that it is necessary to remove the residual particulate matter from the filter 32 by operating the regeneration control start switch 39. This is displayed on the display screen 38a (step S150). The limit value ΔM0 of the accumulation amount deviation ΔM is a value set in advance by experiments or the like as a PM accumulation amount that can appropriately remove the remaining PM without causing problems such as melting of the filter 32.

  Next, the controller 4 reads the operation signal of the regeneration control start switch 39, the command signal of the engine control dial 2, and the detection signal of the position detection device 35 (step S155), and the regeneration control start switch 39 starts the second regeneration combustion from the OFF position. It is determined whether or not an ON position for instructing the start of control (described later) has been operated (whether it has been turned ON) (step S160), and the target rotation is determined from the command signal of the engine control dial 2 and the detection signal of the position detector 35 It is determined whether or not the number is set to low idle and the gate lock lever 22 is operated to be raised to the second position B (whether or not the gate lock is turned on) (step S165). If there is, the process returns to step S150, and steps S150 to S165 are performed. A repeat. When all the determinations in steps S160 and S165 are Yes, complete combustion control (second regeneration combustion control) is started (step S170). Here, the complete combustion control means that the electronic governor 1a is controlled so that the rotational speed of the engine 1 is maintained at a predetermined rotational speed Na, and the fuel injection device 40 for regeneration is controlled so that the fuel into the exhaust pipe 31 is controlled. In this control, PM remaining on the filter 32 is burned and removed by performing injection. In this complete combustion control, the predetermined rotation speed Na of the engine 1 is a rotation speed capable of raising the temperature of the exhaust gas of the engine 1 to a temperature higher than the activation temperature of the oxidation catalyst 33, for example, 1800 rpm It is about medium speed. In this way, by raising the temperature of the exhaust gas of the engine 1 to a temperature higher than the activation temperature of the oxidation catalyst 33, the oxidation catalyst 33 is activated and the exhaust gas temperature is further increased, so that the PM remaining in the filter 32 can be ensured. It can be burned off. In this complete combustion control, the controller 4 switches the target rotational speed of the engine 1 from the target rotational speed (low speed idle rotational speed) indicated by the engine control dial 2 to a predetermined rotational speed Na, and the predetermined rotational speed Na (target rotational speed). Number) and the actual engine speed detected by the engine speed detector 3, the fuel injection command signal of the electronic governor 1a is calculated and output to the electronic governor 1a. Thereby, the rotation speed of the engine 1 is controlled to be the predetermined rotation speed Na.

  During complete combustion control, in step S175, the command signal of the engine control dial 2, the detection signal of the position detection device 35, and the detection signal of the pressure detection device 41 are read, and the engine control dial 2, It is determined whether any of the operation levers of the gate lock lever 22 and the remote control valves 25, 26, and 27 has been operated (step S180), and when one of them (for example, the gate lock lever 22) is operated, Since the complete combustion control is being performed, the construction machine is displayed on the display screen 38a of the display device (monitor) 38 (step S185), and the instruction by these operations is invalidated.

  Then, after the start of complete combustion control, it is determined whether the control time has passed a predetermined time Tb (step S190), and when the predetermined time Tb has passed, the control is terminated (step S195).

  In the above, the regeneration fuel injection device 40 constitutes a regeneration device that raises the temperature of the exhaust gas by injecting fuel into the exhaust gas and burns and removes the particulate matter deposited on the filter 32, and the engine control dial. 2, the rotation speed detection device 3, the exhaust gas temperature detection device 37, the fuel injection command calculation function of the controller 40, and the processing functions of steps S100 to S125 of the flowchart shown in FIG. The accumulated amount estimated value M of the particulate matter is calculated, and when the estimated amount M becomes equal to or greater than a predetermined accumulated amount limit value M0, the regeneration device (regeneration fuel injection device 40) is operated by the first regeneration combustion control. The first regeneration control means for combusting and removing the particulate matter deposited on the filter 32 is configured, and the differential pressure detector 36 and the controller 4 are shown in FIG. The processing functions of steps S130 to S145 in the flowchart detect the differential pressure across the filter 32, and when the differential pressure across the filter 32 is greater than or equal to a preset differential pressure limit value ΔP0, the accumulated amount estimated value M at that time And a second regeneration control means for determining whether or not it is necessary to remove the residual particulate matter from the filter 32 based on the difference ΔM between the value and the accumulation amount limit value M0.

  Further, in the present embodiment, the second regeneration control means, in steps S150 to S170 of the flowchart shown in FIG. 4, sets the difference ΔM between the accumulation amount estimated value M and the accumulation amount limit value M0 to a preset accumulation amount difference limit. If the value ΔM0 is exceeded, it is determined that the residual particulate matter of the filter 32 needs to be removed by combustion, and the residual particulate matter of the filter 32 is removed by combustion by the second regeneration combustion control, which has a higher combustion effect than the first regeneration combustion control. Process to do.

  Furthermore, in the present embodiment, the second regeneration control means performs a filter as a process for burning and removing the residual particulate matter of the filter 32 by the second regeneration combustion control in steps S150 to S170 of the flowchart shown in FIG. When the regeneration control start switch 39 (regeneration control start instructing device) is operated thereafter, the second regeneration combustion control is started.

  Next, the operation principle of the exhaust gas purification system of the present embodiment configured as described above will be described with reference to FIGS.

  FIG. 7 shows the change in the differential pressure across the filter 32 and the estimated PM deposition amount of the filter 32 when PM deposition proceeds from a state where the residual particulate matter (residual PM amount) of the filter 32 is zero. FIG. 7A shows a change in the differential pressure across the filter 32, and FIG. 7B shows a change in the estimated PM accumulation amount of the filter 32. FIG. 8 is a diagram showing the relationship between the change in the differential pressure across the filter 32 and the change in the estimated PM deposition amount of the filter when PM deposition proceeds from a state in which the remaining PM amount of the filter 32 is not zero. 8A shows the change in the differential pressure across the filter 32, and FIG. 8B shows the change in the estimated PM accumulation amount of the filter 32. In these figures, M0 and ΔP0 are the deposition amount limit value and the differential pressure limit value, respectively.

  As described above, the differential pressure limit value ΔP0 is equal to the estimated deposition amount limit value M0 when the PM deposition proceeds from the state where the remaining PM amount of the filter 32 is zero. Is set in advance as a value equal to the differential pressure ΔP before and after the filter 32 at the time when the pressure reaches. When the differential pressure limit value ΔP0 is set in this way, when the residual PM amount of the filter 32 is zero, the changes in the front-rear differential pressure ΔP and the accumulation amount estimated value M are as shown in FIGS. 7 (a) and 7 (b). become.

  That is, when PM accumulation proceeds from a state in which the remaining PM amount of the filter 32 is zero, as shown in FIG. 7B, the estimated PM amount M calculated by the regeneration combustion control of the controller 4 is It increases from zero (initial value = 0) and reaches the deposition amount limit value M0 at time t1. At this time, the differential pressure ΔP before and after the filter 32 at the start of the first regeneration combustion control is a value ΔP1 derived from the inherent pressure loss of the filter 32 as shown in FIG. When the PM deposition amount increases, the PM deposition amount increases as the PM deposition amount increases, and reaches the differential pressure limit value ΔP0 at time t1 when the PM deposition amount estimated value M reaches the deposition amount limit value M0.

  Even when PM accumulation proceeds from a state where the remaining PM amount of the filter 32 is not zero, the PM accumulation amount estimated value M calculated by the regeneration combustion control of the controller 4 is indicated by a solid line in FIG. Thus, it increases from zero (initial value = 0) and reaches the deposition amount limit value M0 at time t1. However, in practice, since PM remains in the filter 32, when the residual PM amount is calculated as Ma and the initial value of the PM accumulated amount estimated value M is calculated as Ma in the regeneration combustion control, the PM accumulated amount is estimated. The value M reaches the deposition amount limit value M0 at time t2 earlier than time t1. At this time, the differential pressure ΔP before and after the filter 32 at the start of the first regeneration combustion control is set to a residual PM amount Ma rather than a value ΔP1 derived from the inherent pressure loss of the filter 32 as shown by a solid line in FIG. ΔP2 that is larger by a corresponding amount, and thereafter, when the PM deposition amount increases with the passage of time, the PM deposition amount increases as the PM deposition amount increases, and the time when the PM deposition amount estimated value M reaches the deposition amount limit value M0 The pressure difference limit value ΔP0 is reached at time t2 earlier than t1. Assuming that the PM accumulation amount estimated value M at time t2 is M1, the deviation ΔM (= M0−M1) between the accumulation amount limit value M0 and the PM accumulation amount estimation value M (= M1) is the remaining PM amount. Corresponds to Ma.

  In this way, when the PM deposition proceeds from the state where the residual PM amount of the filter 32 is zero, the differential pressure limit value ΔP0 is reached when the PM deposition amount estimated value M reaches the deposition amount limit value M0. When the residual PM amount is not zero (when the residual PM amount = Ma), the front-rear differential pressure ΔP of the filter 32 is equal to the residual PM amount Ma. If the difference ΔM (= M0−M1) between the accumulation amount limit value M0 and the PM accumulation amount estimation value M (= M1) at that time is calculated, the remaining PM amount Ma can be obtained. Based on the difference ΔM, it is possible to determine whether or not combustion removal of the remaining PM of the filter 32 is necessary.

  The present invention performs regenerative combustion control as shown in FIG. 4 based on the above knowledge. That is, in step S130 of FIG. 4, the front-rear differential pressure ΔP of the filter 32 is read by the detection signal of the differential pressure detection device 36, and in step S135, when the front-rear differential pressure ΔP becomes equal to or greater than the differential pressure limit value ΔP0, in step S140. Then, a deposit amount deviation ΔM (= M0−M1) which is a difference between the deposit amount limit value M0 and the PM deposit amount estimated value M (= M1) is calculated. When the accumulation amount deviation ΔM (remaining PM amount Ma) exceeds the limit value ΔM0 in step S145, complete combustion control is started by an operator's operation in steps S150 to S170. As a result, residual PM that remains unburned by normal combustion control (first regeneration combustion control) is removed by combustion as appropriate, and excessive accumulation of actual PM when the estimated amount of accumulation reaches the limit value is prevented. Reproduction can be performed appropriately. Further, by appropriately regenerating the DPF, it is possible to prevent the DPF from being melted and the catalyst from being deteriorated due to combustion of an excessive amount of PM, and to prevent the deterioration of the fuel consumption due to the increase in the engine back pressure.

  Further, the deposit amount deviation ΔM (= M0−M1), which is the difference between the deposit amount limit value M0 and the PM deposit amount estimated value M (= M1), exceeds the limit value ΔM0, and it is necessary to remove the remaining PM from the filter 32 by combustion. In step S170, the remaining PM of the filter 32 that could not be combusted by the normal combustion control is effectively removed by performing the complete combustion control having a higher combustion effect than the normal combustion control in step S170. can do. In particular, in this embodiment, as complete combustion control, the engine speed is maintained at a predetermined value Na and combustion control (second regeneration combustion control) is performed. Therefore, the exhaust gas temperature of the engine 1 is increased, and the filter The remaining 32 PM can be reliably removed by combustion.

Further, in the present embodiment, when performing complete combustion control (second regeneration combustion control), it is indicated on the display screen 38a of the display device (monitor) that the remaining PM of the filter 32 needs to be removed by combustion in step S150. After that, when the regeneration control start switch 39 is operated to the ON position in step S160, complete combustion control is started. Here, by displaying on the display screen 38a of the display device (monitor) that the remaining PM of the filter 32 needs to be burned and removed, the operator understands the necessity of performing the manual regeneration and performs the work by the work vehicle. Stop. As a result, since the operator operates the regeneration control start switch 39 to the ON position in a state where the work is stopped, the remaining PM can be burned in a state where the state of the vehicle body and the engine 1 is stable and there is little disturbance. When the complete combustion control (second regeneration combustion control) is performed, the target engine speed is set to low idle and the gate lock lever 22 is moved to the second position B. When complete, the complete combustion control is started. As a result, while the gate lock lever 22 is in the second position B, even if the operator inadvertently operates the operation levers of the remote control valves 25, 26, and 27 to operate the driven body such as the front work machine 102, Since the driving body does not operate, once the complete combustion control is started, the combustion control in the stable state of the DPF device 34 without the vehicle body operation can be performed to the end, and the remaining PM of the filter 32 is surely ensured. Can be burned away. When the complete combustion control is completed, the engine speed is lowered to low idle, so that the operator can know the end of the complete combustion control by the engine sound.

  Further, during complete combustion control, in step S175, the command signal of the engine control dial 2, the detection signal of the position detection device 35, and the detection signal of the pressure detection device 41 are read. In step S180, the engine is based on these signals. It is determined whether any of the operation levers of the control dial 2, the gate lock lever 22, and the remote control valves 25, 26, and 27 is operated, and when any of them (for example, the gate lock lever 22) is operated, step S185 is performed. At this time, since the complete combustion control is currently in progress, the construction machine is displayed on the display screen 38a of the display device (monitor) 38 to indicate that the operation is not permitted, and the instruction by these operations is invalidated. As a result, even if the operator inadvertently operates those operating means during the complete combustion control, the complete combustion control can be performed without stopping, and the operator notices that the complete combustion control is being performed. Can be properly reproduced.

  A second embodiment of the present invention will be described with reference to FIG.

  FIG. 9 is a flowchart showing the calculation processing contents of the regeneration combustion control (first and second regeneration combustion control) of the controller in the exhaust gas purification system of the present embodiment. In the figure, the same parts as those shown in FIG.

  In the present embodiment, the processing content of the second regeneration combustion control is different from that of the first embodiment.

  That is, in FIG. 9, the processing from step S100 to S145 is the same as that of the first embodiment. In step S145, a limit value (threshold value) ΔM0 (described later) set in advance as a threshold is a deposit amount deviation ΔM (= M0−M) obtained by subtracting the PM deposit amount estimated value M from the limit value M0 of the PM deposit amount. It is determined whether it has been exceeded, and if it is No (if the accumulation amount deviation ΔM is equal to or less than the limit value ΔM0), the process proceeds to step S115, and the first regeneration combustion control is performed. The contents of the first regeneration combustion control are the same as the normal combustion control in the first embodiment, and the filter 32 is controlled by controlling the regeneration fuel injection device 40 to inject fuel into the exhaust pipe 31. The accumulated PM is removed by combustion. On the other hand, when the determination in step S145 is Yes (when the accumulation amount deviation ΔM exceeds the limit value ΔM0), the particulate matter is added to the filter 32 even though the first regeneration combustion control is performed. In this case, the controller 4 starts the second regeneration combustion control (step S170A). The contents of the second regeneration combustion control are the same as the normal combustion control in the first embodiment, and the filter 32 is controlled by controlling the regeneration fuel injection device 40 to inject fuel into the exhaust pipe 31. The accumulated PM is removed by combustion. Then, after the start of the second regeneration combustion control, it is determined whether the control time has passed the predetermined time Tc (step S185A), and the second regeneration combustion control is continued until the control time has passed the predetermined time Tc. Here, the predetermined time Tc is set longer than the predetermined time Ta related to the control time of the first regeneration combustion control, for example, Tc = 2Ta. Thus, the second regeneration combustion control is performed for a longer time than the first regeneration combustion control, and the control is terminated when the predetermined time Tc elapses (step S190).

  Also in the present embodiment configured as described above, in step S135, the differential pressure ΔP before and after the filter 32 becomes equal to or greater than the differential pressure limit value ΔP0, and in step S145, the accumulation amount deviation ΔM (residual PM amount Ma) is the limit value ΔM0. Since the second regeneration combustion control is started in step S170A, the residual PM remaining unburned by the first regeneration combustion control is appropriately burned and removed as appropriate in the step S170A, and the regeneration of the DPF is appropriately performed. It can be carried out.

  In addition, when the second regeneration combustion control is started, the second regeneration combustion control is performed in step S185A for a time longer than the first regeneration combustion control for a time Tc, so that the remaining PM remaining after the first regeneration combustion control is surely combusted. Can be removed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made within the spirit of the present invention.

  1. In the above embodiment, the fuel injection for regeneration is performed by the fuel injection device 39 for regeneration provided in the exhaust pipe 31, but the in-cylinder (in-cylinder) injection system of the engine 1 by the electronic governor 1a is used, Regeneration fuel may be injected into the exhaust gas by performing sub-injection (post-injection) for injecting fuel in the expansion stroke after the main injection of multistage injection. For example, such a technique is disclosed in Patent Document 1 ( JP-A-2005-282545), JP-A-2006-37925, JP-A-2002-276340, and the like.

  2. In the first embodiment, in the complete combustion control, the engine speed is maintained at a predetermined value Na to increase the exhaust gas temperature and the combustion control (second regeneration combustion control) is performed. By applying an appropriate load, the exhaust gas temperature of the engine 1 can be more reliably raised. As a technique for applying a load to the engine 1, for example, there are the following.

  (1) An electromagnetic on-off valve is provided on the most downstream side of the center bypass line passing through the flow rate control valves 17 to 19 in the hydraulic system of FIG. 2, and the discharge pressure of the hydraulic pump 11 is reduced by closing the electromagnetic on-off valve 29. The relief pressure of the engine 1 is increased and a load is applied to the engine 1 by applying a load to the hydraulic pump 11.

  (2) When injecting the fuel for regeneration into the exhaust gas, a load operation is performed by restricting the flow path of the exhaust pipe with a throttle valve provided in the exhaust pipe, and the engine 1 is loaded.

  (3) The above two methods (1) and (2) are used in combination.

  3. In the above embodiment, the present invention is applied to a hydraulic excavator that is a construction machine as a work vehicle. However, the present invention may be applied to a work vehicle other than the hydraulic excavator. As work vehicles other than the hydraulic excavator, for example, there are a wheel loader, a crane truck, and the like. In this case as well, the same effect as in the above embodiment can be obtained.

  4). In the above embodiment, the pressure detection device 41 is provided in the discharge line of the hydraulic pump 11 to detect whether the operation levers of the remote control valves 25, 26, 27 are operated, and the discharge pressure of the hydraulic pump 11 is detected. However, the pilot pressure generated by the remote control valves 25, 26, and 27 may be detected, or the movements of the operation levers and the flow control valves 17 to 19 may be detected.

It is a figure showing the whole exhaust-gas purification system composition of a work vehicle concerning a 1st embodiment of the present invention. It is a figure which shows the hydraulic system mounted in the construction machine (for example, hydraulic excavator) which is a work vehicle. It is a figure which shows the external appearance of the hydraulic shovel which is an example of the construction machine provided with the hydraulic system shown in FIG. It is a flowchart which shows the arithmetic processing content of a controller. It is a figure which shows PM emission amount map used for calculating PM emission amount. It is a figure which shows the PM combustion amount map used for calculating PM combustion amount. FIG. 7 is a diagram showing the relationship between the change in the differential pressure across the filter and the change in the estimated PM deposition amount of the filter when PM deposition proceeds from a state where the remaining PM amount of the filter is zero, (A) shows the change in the differential pressure across the filter, and FIG. 7 (b) shows the change in the estimated PM deposition amount of the filter. FIG. 8 is a diagram showing the relationship between the change in the differential pressure across the filter and the change in the estimated PM deposition amount of the filter when PM deposition proceeds from a state in which the remaining PM amount of the filter is not zero; a) shows the change in the differential pressure across the filter, and FIG. 8 (b) shows the change in the estimated PM deposition amount of the filter. It is a flowchart which shows the arithmetic processing content of the controller in the exhaust-gas purification system of the working vehicle concerning the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diesel engine 1a Electronic governor 2 Engine control dial (3rd operation means; 4th operation means)
DESCRIPTION OF SYMBOLS 3 Rotational speed detection apparatus 4 Controller 5 Key switch 11 Hydraulic pump 12 Pilot pump 13 Hydraulic motors 14 and 15 Hydraulic cylinders 17 to 19 Flow control valve 20 Pilot hydraulic source 21 Pilot relief valve 22 Gate lock lever (second operation means; fourth Operation means)
23 Electromagnetic switching valve 24 Pilot oil passage 25, 26, 27 Remote control valve (first operating means; fourth operating means)
29 Main relief valve 31 Exhaust pipe 32 Filter 33 Oxidation catalyst 34 DPF device 35 Position detection device 36 Differential pressure detection device 37 Exhaust temperature detection device 38 Display device (monitor)
38a Display screen 39 Reproduction control start switch (Reproduction control start instruction device)
40 Regeneration fuel injection device (regeneration device)
41 Pressure detector 100 Lower traveling body 101 Upper revolving body 102 Front work machine 104a, 104b Traveling motor 105 Swing motor 106 Engine room 107, 107B Driver's cab 108 Driver's seat 111 Boom 112 Arm 113 Bucket 114 Boom cylinder 115 Arm cylinder 116 Bucket cylinder

Claims (8)

A filter device including a filter disposed in an exhaust system of a diesel engine and collecting particulate matter contained in exhaust gas;
In an exhaust gas purification system for a work vehicle, which has a regeneration device that raises the temperature of the exhaust gas by injecting fuel into the exhaust gas and burns and removes particulate matter deposited on the filter,
Based on the operating state of the engine, the accumulated amount estimated value of the particulate matter accumulated in the filter is calculated, and when the estimated accumulated amount exceeds a preset accumulated amount limit value, the regeneration device performs the first regeneration combustion control. And a first regeneration control means for burning and removing the particulate matter deposited on the filter,
A differential pressure across the filter is detected, and when the differential pressure across the filter is greater than or equal to a preset differential pressure limit value, the filter is based on the difference between the estimated accumulation amount and the accumulated amount limit value at that time. An exhaust gas purification system for a work vehicle, comprising: a second regeneration control means for determining whether or not the remaining particulate matter needs to be removed by combustion. The exhaust gas purification system for a work vehicle according to claim 1,
The second regeneration control unit determines that the residual particulate matter needs to be burned and removed from the filter when a difference between the accumulation amount estimated value and the accumulation amount limit value exceeds a preset accumulation amount difference limit value. An exhaust gas purification system for a work vehicle that performs a process for burning and removing the residual particulate matter of the filter by a second regeneration combustion control that has a higher combustion effect than the first regeneration combustion control. The exhaust gas purification system for a work vehicle according to claim 2,
In the second regeneration combustion control, the second regeneration control means maintains the engine speed at a predetermined value and operates the regeneration device in this state. . The exhaust gas purification system for a work vehicle according to claim 2,
In the second regeneration combustion control, the second regeneration control means makes the operation time of the regeneration device longer than the operation time of the regeneration device in the first regeneration combustion control. system. The exhaust gas purification system for a work vehicle according to claim 2 or 3,
A monitor and a playback control start instruction device;
The second regeneration control means informs the monitor that the residual particulate matter of the filter needs to be removed by combustion as a process for burning and removing the residual particulate matter of the filter by the second regeneration combustion control. And the second regeneration combustion control is started when the regeneration control start instruction device is operated and then the regeneration control start instruction device is operated. The exhaust gas purification system for a work vehicle according to claim 5,
The work vehicle makes the work driven body driven by the power of the engine, first operation means for instructing the operation of the work driven body, and commands from the first operation means effective. Second operating means that is selectively operated to a first position and a second position that invalidates the command of the first operating means;
The second regeneration control means starts the second regeneration combustion control when the second operation means is operated to the second position and the regeneration control start instruction device is operated. Exhaust gas purification system. The exhaust gas purification system for a work vehicle according to claim 5,
The work vehicle has third operation means for setting a target engine speed of the engine,
The second regeneration control means starts the second regeneration combustion control when the target engine speed of the engine is set to low idle by the third operation means and the regeneration control start instruction device is operated. An exhaust gas purification system for work vehicles. The exhaust gas purification system for a work vehicle according to claim 5,
The work vehicle has fourth operation means for commanding the operation of the work vehicle,
The second regeneration control means displays on the monitor that the second regeneration combustion control is being performed when the fourth operation means is operated during the execution of the second regeneration combustion control. Vehicle exhaust gas purification system.

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