JP5572826B2 - Exhaust gas purification system - Google Patents

Description

  The present invention relates to an exhaust gas purification system, and in particular, the particulate matter contained in the exhaust gas is collected by a filter to purify the exhaust gas, and the particulate matter collected in the filter is appropriately incinerated and removed. The present invention relates to an exhaust gas purification system that regenerates exhaust gas.

  A work vehicle such as a hydraulic excavator is equipped with a diesel engine as a drive source. The emission amount of particulate matter (PM: particulate matter: hereinafter referred to as PM) discharged from the diesel engine is NOx, Regulations have been strengthened year by year along with CO and HC. An exhaust gas purification system that collects PM with a filter called a diesel particulate filter (DPF: Diesel Particulate Filter) and reduces the amount of PM discharged to the outside is known for such regulations. . In this exhaust gas purification system, when the amount of PM accumulation on the filter increases, the filter clogs, which increases the exhaust pressure of the engine and induces deterioration of fuel consumption. The collected PM is combusted as appropriate to remove the clogging of the filter, and the filter is regenerated.

  The regeneration of the filter is usually performed by using an oxidation catalyst. The oxidation catalyst may be disposed upstream of the filter, directly supported by the filter, or both. In either case, in order to activate the oxidation catalyst, the temperature of the exhaust gas Must be higher than the activation temperature of the oxidation catalyst. If the exhaust gas temperature is high enough, it will self-regenerate, but the exhaust gas temperature may not be sufficient and self-regeneration may not be possible, or self-regeneration may not sufficiently incinerate and remove PM. There is a technique called forced regeneration in which the temperature is raised to a temperature higher than the activation temperature. In this forced regeneration, a method of raising the temperature of exhaust gas by performing sub-injection (post-injection) for injecting fuel in the expansion stroke after in-cylinder main injection of the engine, exhaust by a fuel injection device for regeneration provided in the exhaust pipe There is a technique for injecting fuel into exhaust gas flowing through a pipe to raise the temperature of the exhaust gas.

  Further, the forced regeneration of the filter includes manual regeneration that starts regeneration by an operator's operation input and automatic regeneration that automatically starts regeneration. Manual regeneration is performed as follows. First, the PM accumulation amount (accumulation amount) of the filter is estimated, and when the PM accumulation amount reaches a preset threshold value, the operator is warned that manual regeneration is performed. When the operator operates the manual regeneration switch, regeneration starts. Patent Document 1 discloses a technique related to manual regeneration. On the other hand, automatic regeneration is performed when the PM accumulation amount reaches the threshold value or when a predetermined time has elapsed. Patent Document 2 discloses a technique related to automatic reproduction. In both manual regeneration and automatic regeneration, the PM accumulation amount is generally obtained by detecting the differential pressure across the filter and calculating based on the detected value of the differential pressure.

  By the way, work vehicles such as a wheel loader and a hydraulic excavator may work in an environment where flammable materials exist around. For example, as such work, there are a work of transporting wood chips indoors, a work of dismantling that generates dust and the like. When the filter is forcibly regenerated, the exhaust gas temperature is maintained at a high temperature for a predetermined time (for example, several minutes). Therefore, if the filter is forcibly regenerated in the above environment, there is a risk of ignition and danger.

  In this situation, in manual regeneration, the manual regeneration switch is not operated at the operator's discretion, and the work vehicle is moved to a place where there are no flammable materials (recyclable place), ensuring safety and starting manual regeneration. To do.

  On the other hand, in automatic reproduction, since reproduction automatically starts regardless of the operator's judgment, a reproduction prohibiting means is provided, and automatic reproduction is prohibited by operating the reproduction prohibiting means according to the operator's judgment (Patent Document 2). Then, the operator appropriately interrupts the work, moves the work vehicle to a place where there is no flammable material (recyclable place), secures safety, cancels the prohibition of regeneration, and resumes automatic regeneration.

International Publication No. WO2009 / 060719 JP 2009-79500 A

  However, if the work is frequently interrupted, the work efficiency is remarkably deteriorated. From the standpoint of the operator, it is preferable to secure the working time as long as possible. On the other hand, if the operation is continued while prohibiting automatic regeneration (forced regeneration), PM continues to accumulate, causing problems such as abnormal rise in the internal temperature of the filter due to combustion of a large amount of collected PM and damage to the DPF derived from it. May cause.

  By the way, even if forced regeneration is prohibited, as described above, self-regeneration is performed when the exhaust gas temperature is moderate. The exhaust gas temperature during self-regeneration is lower than the exhaust gas temperature during forced regeneration, and the PM incineration removal amount during self-regeneration is smaller than the PM incineration removal amount during forced regeneration, but if self-regeneration is performed Part of PM is incinerated and removed.

  The exhaust gas temperature during forced regeneration is high, and there is a danger of ignition if there are combustibles in the surroundings, whereas the exhaust gas temperature (250 ° C or higher) during self regeneration is the exhaust gas during forced regeneration. Compared to the gas temperature (about 600 ° C.), the risk of ignition is extremely low.

  In other words, it is possible to expect PM incineration removal by self-regeneration during work. However, even during work, when idling (during non-operation), there is a possibility that the exhaust gas temperature may rapidly decrease (for example, about 100 ° C.), PM incineration removal by self-regeneration cannot be expected, PM deposition proceeds, The possibility of damage to the DPF increases.

  An object of the present invention is to provide an exhaust gas purification system that can prevent DPF breakage even when regeneration is prohibited, and can secure working time by mitigating the progress of PM deposition.

In order to achieve the above object, the present invention is mounted on a construction machine including a diesel engine and a plurality of driven bodies driven by the power of the engine, and disposed in an exhaust system of the engine. the particulate matter deposited on the filter by performing the fuel injection incineration removed includes a filter for trapping particulate matter, in an exhaust system of the engine during a forced regeneration apparatus for reproducing the filter, the When the amount of particulate matter deposited on the filter is greater than a first threshold value that is an automatic regeneration start value, the forced regeneration device is started to perform automatic regeneration control, and the particulate matter deposited on the filter is deposited. in the exhaust gas purification system comprising a reproduction control apparatus amount to stop the automatic regeneration control becomes smaller than the second threshold value is a reproduction end value, non of the plurality of the driven body A non-operation state detecting means for detecting a work state, is operable to ON position and an OFF position, a reproduction inhibition means for inhibiting the operation of the forced regeneration apparatus when operated to the ON position, the non-operation state detecting means detects the non-operation state, the when the reproduction inhibition means inhibits the operation of the forced regeneration apparatus, by applying a load to the engine increases the temperature of the exhaust gas, the deposited particulate matter by self-renewal It shall comprise a heating device for burning removal.

  By providing temperature rise control in this way, when the exhaust gas temperature rises and self-regeneration occurs, a part of the deposited PM is burned and removed, and PM accumulates continuously, but the PM deposition progresses. can do. By mitigating the progress of PM deposition, it is possible to extend the time until the amount of PM deposition reaches the limit value, and to secure working time. Since the operator completes the work within the work time and performs forced regeneration at a recyclable place, the DPF can be prevented from being damaged.

  (2) In the above (1), preferably, further comprising an exhaust gas temperature detecting device for detecting the temperature of the exhaust gas, and the temperature raising means further detects when the exhaust gas temperature detecting device detects a temperature lower than a threshold value. Operate.

  Thereby, when the exhaust gas temperature is a temperature at which self-regeneration is possible, unnecessary fuel temperature rise can be avoided and fuel consumption can be improved.

  (3) In the above (1), preferably, the temperature raising means applies a load to the engine by increasing the engine speed.

  Thereby, the temperature raising means can raise the temperature of the exhaust gas.

  (4) In the above (1), preferably, the construction machine includes a hydraulic pump that is driven by the engine and a hydraulic actuator that is driven by discharge oil of the hydraulic pump and drives the driven body. The temperature raising means is provided in the hydraulic circuit and applies a hydraulic load to the engine.

  Thereby, the temperature raising means can raise the temperature of the exhaust gas.

  (5) In the above (1), preferably, the construction machine sets the engine speed to an idle speed when the non-operation state detection means detects a predetermined second non-operation state of the plurality of driven bodies. An auto idle control means for setting is further provided, and the temperature raising means invalidates the auto idle control and maintains the engine speed.

  Thereby, the temperature raising means can suppress the exhaust gas temperature decrease and maintain the exhaust gas temperature (temperature rise compared to the time of auto idle control).

  The non-operation state of the temperature rise control start condition and the non-operation state (second non-operation state) of the auto idle control start condition may be distinguished or may not be distinguished.

  According to the present invention, it is possible to prevent the DPF breakage and to secure the working time even when regeneration is prohibited by mitigating the progress of PM deposition.

1 is a diagram illustrating an overall configuration of an exhaust gas purification system (first embodiment). FIG. It is a figure which shows the hydraulic circuit mounted in a hydraulic shovel. It is a figure which shows the external appearance of a hydraulic shovel. It is a figure which shows the functional block of a controller. It is a flowchart which shows the content of the calculation process of the regeneration control by an engine controller. It is a flowchart which shows the content of the calculation process of the temperature rising control at the time of reproduction | regeneration prohibition by a vehicle body controller. It is an example of the time passage of exhaust gas temperature. It is a figure which shows the time passage of PM deposition amount. It is a flowchart which shows the content of the calculation process of the temperature rising control at the time of reproduction | regeneration prohibition by a vehicle body controller (modification). It is a figure which shows the relationship between the discharge pressure and discharge flow rate of a hydraulic pump, and an engine output. It is a flowchart which shows the content of the calculation process of the temperature rising control at the time of reproduction | regeneration prohibition by a vehicle body controller (2nd Embodiment).

<First embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

~Constitution~
FIG. 1 is a diagram showing an overall configuration of an exhaust gas purification system for a construction machine according to this embodiment of the present invention. In FIG. 1, a construction machine (for example, a hydraulic excavator) is equipped with a diesel engine 1. The engine 1 includes an electronic governor 1a that is an electronic fuel injection control device. The target rotational speed of the engine 1 is commanded by the engine control dial 2, and the actual rotational speed of the engine 1 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 controls the electronic governor 1a based on the command signal (target rotational speed) and the detection signal (actual rotational speed). To control the rotational speed and torque of the engine 1.

  The operation levers 28 and 29 (see FIG. 2) and the gate lock lever 5 are provided in the cabin 107 of the excavator. The gate lock lever 5 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 a raised position that opens the entrance of the driver's seat 108. The gate lock lever 5 has a position detection sensor 5a for detecting the operation position.

  The exhaust gas purification system is disposed in an exhaust pipe 31 that constitutes an exhaust system of the engine 1, and includes a filter 32 that collects particulate matter contained in the exhaust gas and an oxidation catalyst 33 that is disposed on the upstream side of the filter 32. A DPF device 34, a differential pressure detection device 36 for detecting the differential pressure across the upstream and downstream sides of the filter 32 (pressure loss of the filter 32), and an exhaust gas that is installed upstream of the filter and detects the temperature of the exhaust gas A temperature detecting device 37, a regeneration prohibiting switch 38 for instructing regeneration prohibiting, and a regeneration fuel injection device 39 provided between the engine 1 of the exhaust pipe 31 and the DPF device 34 for raising the temperature of the exhaust gas are provided. Yes. The oxidation catalyst 33 and the regeneration fuel injection device 39 constitute a regeneration device for regenerating the filter 32 by burning and removing PM (particulate matter) deposited on the filter 32.

  The regeneration prohibiting switch 38 is an operating means for instructing prohibition of the operation of the regeneration fuel injection device 39 (regeneration prohibition of the filter 32), which is disposed at a position easily operated by the operator in the cabin 107 of the excavator. When the prohibit switch 38 is operated to the ON position, a command signal instructing prohibition of reproduction is output. Note that the reproduction prohibition switch 38 may be a setting screen displayed on the display device 6. The operation switch 6b is operated to set ON / OFF.

  FIG. 2 is a diagram illustrating a hydraulic circuit mounted on a construction machine (for example, a hydraulic excavator). The hydraulic circuit includes a variable displacement main hydraulic pump 11 and a fixed displacement pilot pump 12 driven by the engine 1, a hydraulic motor 13 and a hydraulic cylinder 14 driven by pressure oil discharged from the hydraulic pump 11, And a plurality of hydraulic actuators 15 including pilot-operated flow control valves 17 to 19 that 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. A main flow pressure control valve, a main pressure that regulates the upper limit of the discharge pressure of the main hydraulic pump 11 and the pilot relief valve 21 that forms the pilot hydraulic power source 20 while keeping the pressure of the pressure oil discharged from the pilot pump 12 constant. Provided on the downstream side of the center bypass line connecting the relief valve 22 and the flow control valves 17 to 19 in series. A control valve 30, an electromagnetic switching valve 23 connected to the downstream side of the pilot hydraulic pressure source 20, and ON / OFF controlled according to the open / close state of the gate lock lever 5 provided at the driver's seat entrance of the hydraulic excavator, Remote control valves 25, 26, 27 that are connected to a pilot oil passage 24 downstream of 23 and generate control pilot pressures a to f for operating the flow control valves 17 to 19 using the hydraulic pressure of the pilot hydraulic power source 20 as a source pressure. And.

  The hydraulic pump 11 tilts the hydraulic pump 11 so that the absorption torque (consumption torque) of the hydraulic pump 11 does not exceed a maximum absorption torque that is a predetermined value based on the discharge pressure (the amount of tilt of the swash plate; It has a regulator 11a for controlling the displacement or capacity).

  The remote control valves 25, 26 and 27 are operated by left and right operation levers 28 and 29 provided on the left and right of the driver's seat 108 (see FIG. 1). The operation levers 28 and 29 can each be operated in the cross direction. When the operation lever 28 is operated in one direction of the cross, the remote control valve 25 is operated, and when the operation lever 28 is operated in the other direction of the cross, the remote control valve 27 is operated. When the operation lever 29 is operated in one direction of the cross, the remote control valve 26 is operated. When the operation lever 29 is operated in the other direction of the cross, a remote control valve (not shown) is operated. When the operation lever 28 is operated in one direction of the cross, if the remote control valve 25 is operated in one direction from the neutral position, the remote control valve 25 generates the control pilot pressure a, and if operated in the opposite direction from the neutral position, the remote control valve 25 is controlled by the control pilot pressure. b is generated. The control pilot pressures a and b are guided to the corresponding pressure receiving portions of the flow control valve 17 via the respective pilot lines 25a and 25b, whereby the flow control valve 17 is switched from the neutral position.

  Similarly, when operating the control lever 28 in the other direction of the cross, if the remote control valve 27 is operated in one direction from the neutral position, the remote control valve 27 generates the control pilot pressure e, and if operated in the opposite direction from the neutral position, the remote control valve 27 is controlled by the control pilot. The pressure f is generated, and the control pilot pressures e and f are guided to the corresponding pressure receiving portions of the flow control valve 19 via the respective pilot lines 27a and 27b, and thereby the flow control valve 19 is switched from the neutral position. When the operation lever 29 is operated in one direction of the cross, when the operation lever 29 is operated in one direction from the neutral position, the control pilot pressure c is generated. When the operation lever 29 is operated in the opposite direction from the neutral position, the control pilot pressure d is generated. d is led to the corresponding pressure receiving portion of the flow control valve 18 through the respective pilot lines 26a, 26b, whereby the flow control valve 18 is switched from the neutral position.

  The hydraulic circuit further includes a shuttle valve group 46 and a pressure sensor 47. The shuttle valve group 46 extracts the highest pressure among the control pilot pressures a to f of the remote control valves 26 to 27 and the control pilot pressures of other operating means. The pressure sensor 47 is connected to an output port of a shuttle valve provided on the most downstream side of the shuttle valve group 46, detects the highest pressure among the control pilot pressures, and detects the presence or absence of an operation.

  The control pilot pressures a to f are communicated and blocked based on the position of the gate lock lever 5.

  When the gate lock lever 5 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 power source 20 is guided to the remote control valves 25, 26, 27. Thus, the flow control valves 17-19 can be operated by the remote control valves 25, 26, 27. When the gate lock lever 5 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 communication of the flow control valves 17 to 19 by the remote control valves 25, 26 and 27 is disabled. That is, when the gate lock lever 5 is raised to the second position B, the remote control valves 25, 26 and 27 (control lever unit) are locked. When the gate lock lever 5 is again lowered to the first position A, the lock is released. For switching the position of the electromagnetic switching valve 23 by the gate lock lever 5, 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 5 is at the first position A, the switch is turned on. When the gate lock lever 5 is operated to the second position B, the switch is turned off (opened) to release the solenoid excitation.

  The control valve 30 is a two-position switching valve having an open position and a closed position. The control valve 30 is in the open position when the solenoid is not excited, and is switched from the open position to the closed position when the solenoid is excited.

  FIG. 3 is a diagram illustrating an appearance of the hydraulic excavator. 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 includes an engine room 106 and a cabin 107. The engine 1 is disposed in the engine room 106. A gate lock lever 5 (FIG. 1) is provided at the entrance of the driver seat 108 in the cabin 107. Control lever units (FIG. 2) incorporating remote control valves 25, 26 and 27 are arranged on the left and right of 108, respectively.

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

  The construction machine may be a wheel loader or a wheeled hydraulic excavator.

~control~
FIG. 4 is a diagram showing functional blocks of the controller 4. The controller 4 includes a vehicle body controller 41, an engine controller 42, and a display controller 43, and these controllers are connected to each other via a communication line 44 to constitute a vehicle body network. The command signal of the engine control dial 2, the detection signal of the position detection sensor 5a and the pressure sensor 47, and the command signal of the regeneration prohibiting switch 38 are input to the vehicle body controller 41, and the detection signal of the rotational speed detection device 3 and the differential pressure detection device. 36, the detection signal of the exhaust temperature detection device 37 is input to the engine controller 42.

The vehicle body controller 41 controls the entire vehicle body such as a hydraulic drive device. For example, the discharge pressure and the discharge flow rate of the hydraulic pump 11 are controlled by controlling the control valve 30 and the regulator 11 a of the hydraulic pump 11.
The engine controller 42 receives a command signal from the engine control dial 2 via the communication line 44, and controls the rotational speed and torque of the engine 1 based on the command signal and a detection signal from the rotational speed detection device 3.

  Further, the engine controller 42 receives the detection signal of the differential pressure detection device 36, estimates the PM accumulation amount, performs regeneration control calculation processing based on the estimated PM accumulation amount, and according to the calculation result, the electronic governor 1a. And the fuel injection device 39 for regeneration is controlled (automatic regeneration control).

  The display controller 43 receives various signals from the rotation speed detection device 3, the differential pressure detection device 36, and the regeneration prohibition switch 38 and the calculation processing result of the forced regeneration control via the communication line 44, and displays them as display signals on the display device 6. The information is sent and displayed on the display screen 6a. In addition, a command signal from the operation switch 6b as a user interface is input.

  FIG. 5 is a flowchart showing the contents of the calculation process of the regeneration control by the engine controller 42.

  It is determined whether or not the estimated accumulation amount based on the detection signal of the differential pressure detection device 36 is larger than a first threshold value that is an automatic regeneration start value (step S11), and if it is determined that the estimated accumulation amount is not larger than the first threshold value, The process of step S11 is repeated until the estimated accumulation amount exceeds the first threshold value.

  If it is determined in step S11 that the estimated accumulation amount is greater than the first threshold, it is determined whether or not regeneration prohibition is commanded (step S12). If it is determined that regeneration prohibition is not commanded (recyclable), automatic regeneration is performed. Control is started (step S13). If it is determined that the reproduction prohibition is instructed, the calculation process is terminated without performing the reproduction control.

  During automatic regeneration control, it is determined whether regeneration prohibition is commanded (step S14), and when it is determined that regeneration prohibition is not commanded (recyclable), the estimated accumulation amount is less than the second threshold value that is the regeneration end value. (Step S15), and if it is determined that the estimated accumulation amount is not smaller than the second threshold value, the regeneration prohibition is instructed or the steps S14 and S15 are continued until the estimated accumulation amount becomes smaller than the second threshold value. Repeat the process.

  If it is determined in step S15 that the estimated accumulation amount has become smaller than the second threshold value, the automatic regeneration control is stopped (step S16), and the calculation process is terminated.

  The automatic regeneration control is performed as follows, for example. First, the rotational speed of the engine 1 is controlled to a predetermined rotational speed Na suitable for forced regeneration control. The predetermined rotation speed Na suitable for the forced regeneration control is a medium speed rotation speed that can raise the temperature of the exhaust gas at that time to a temperature higher than the activation temperature of the oxidation catalyst 33. In this control, the vehicle body controller 41 switches the target rotational speed of the engine 1 from the target rotational speed indicated by the engine control dial 2 to a predetermined rotational speed Na, and the predetermined rotational speed Na (target rotational speed) is changed to the communication line 44. To the engine controller 42. The engine controller 42 feedback-controls the fuel injection amount of the electronic governor 1 a based on the target rotational speed (predetermined rotational speed Na) and the actual rotational speed of the engine 1 detected by the rotational speed detection device 3. Control is performed so that the rotational speed becomes the predetermined rotational speed Na.

  Next, when it is confirmed that the exhaust gas temperature detected by the exhaust temperature detection device 37 has risen to a predetermined temperature (a temperature higher than the activation temperature of the oxidation catalyst 33), the regeneration fuel injection device 39 is controlled to exhaust the exhaust gas. Fuel is injected into the pipe 31. By injecting fuel into the exhaust pipe 31, unburned fuel is supplied to the oxidation catalyst 33. The unburned fuel is oxidized by the oxidation catalyst 33, and the exhaust gas temperature further rises due to the reaction heat obtained at that time. The PM deposited on the filter 32 is removed by incineration.

  When stopping the regeneration control, the target rotational speed is returned to the target rotational speed (low-speed idle rotational speed) indicated by the engine control dial 2, and the control of the regeneration fuel injection device 39 is stopped. Instead of returning the target rotational speed to the target rotational speed (low-speed idle rotational speed) indicated by the engine control dial 2, the engine 1 may be stopped.

  FIG. 6 is a flowchart showing the contents of the temperature rise control calculation process when regeneration is prohibited by the vehicle body controller 41, which is a feature of the present embodiment.

  The vehicle body controller 41 first determines whether or not the prohibition of regeneration is instructed (step S21). If it is determined that the prohibition of regeneration is instructed, it determines whether or not it is in a non-operation state (step S22). If it is determined that the engine is in the operating state, it is determined whether or not the exhaust gas temperature is less than a threshold value (lower limit of self-regenerative temperature) based on the detection signal of the exhaust temperature detection device 37 (step S23). Is determined to be less than the threshold value, the temperature rise control is started (step S24).

  If it is determined in step S22 that the engine is not in the non-operating state (is in the operating state), in step S23, if it is determined that the exhaust gas temperature is not less than the threshold value (is at a temperature that can be self-regenerated), steps S22 to S23 are performed. Repeat the procedure.

  After the temperature increase control is started, any of the determination in step 21 (condition 1), the determination in step 22 (condition 2), and the determination in step 23 (condition 3) is NO (whether any of conditions 1-3 is set) It is determined whether or not (step S25), and if any is determined to be NO, the temperature rise control is stopped (step S26).

  If it is determined in step S25 that none is NO (all conditions 1 to 3 are satisfied), the procedure of step S25 is repeated to continue the temperature increase control.

  If it is determined in step S21 that reproduction prohibition is not instructed (reproduction is possible), the fact is transmitted to the engine controller 42 via the communication line 44. The engine controller 42 performs the regeneration control shown in FIG. 5 (step S10).

  The determination as to whether or not in the non-operation state in step S22 is performed as follows, for example. The vehicle body controller 41 presets a pressure slightly higher than the output pressure of the remote control valves 25 to 27 when the operation levers 28 and 29 are not operated as a threshold, and the pressure detection value of the pressure sensor 47 is lower than the threshold. If it is determined that the state has continued for a predetermined time Ta, it is determined as a non-operation state.

  The temperature increase control start in step S24 is performed as follows, for example. The vehicle body controller 41 switches the target rotational speed of the engine 1 from the target rotational speed indicated by the engine control dial 2 to a slightly higher rotational speed, and transmits the switched target rotational speed to the engine controller 42 via the communication line 44. . The engine controller 42 feedback-controls the fuel injection amount of the electronic governor 1a based on the target rotational speed and the actual rotational speed of the engine 1 detected by the rotational speed detection device 3, and the rotational speed of the engine 1 is controlled by the engine control dial 2. Is controlled so as to be higher than the target rotational speed indicated by. As the engine speed increases, the engine 1 is loaded and the exhaust gas temperature rises.

  The temperature increase control stop in step S26 is performed as follows, for example. The vehicle body controller 41 switches the target rotational speed of the engine 1 to the original target rotational speed indicated by the engine control dial 2 and returns to normal engine control. The engine controller 42 inputs the target rotational speed via the communication line 44, and feeds back the fuel injection amount of the electronic governor 1a based on the target rotational speed and the actual rotational speed of the engine 1 detected by the rotational speed detection device 3. And the engine 1 is controlled so that the engine speed becomes the target engine speed indicated by the engine control dial 2.

-Correspondence with claims-
In the present embodiment, the operation levers 28 and 29, the remote control valves 25 to 27, the shuttle valve group 46, the pressure sensor 47, and the processing in step S22 of the vehicle body controller 41 are non-operation state detection means for detecting the non-operation state of the hydraulic excavator. The regeneration prohibiting switch 38 constitutes a regeneration prohibiting means for prohibiting forced regeneration.

Further, the processing in step S24 of the engine controller 42, the electronic governor 1a of the engine 1 and the vehicle body controller 41 is performed when the non-operation state detecting means detects the non-operation state and the regeneration prohibiting means prohibits the operation of the forced regeneration device. And a temperature raising means for raising the temperature of the exhaust gas.

~ Operation ~
The operation of the exhaust gas purification system of this embodiment will be described.

  During general work, the regeneration prohibiting switch 38 is in the OFF position, and automatic regeneration control is appropriately performed (S21 → S10 → S11 → S12 → S13 → S14 → S15 → S16). By forced regeneration, the exhaust gas temperature becomes about 600 ° C., and accumulated PM can be removed by combustion.

  Here, an indoor work is assumed. FIG. 7 shows an example of the passage of time of the exhaust gas temperature shown for assisting understanding. When working indoors, dust and the like are likely to fly, and PM accumulates on the filter. If the regeneration prohibiting switch 38 is in the OFF position and the PM accumulation amount is larger than the first threshold value, automatic regeneration is started (S21 → S10 → S11 → S12 → 13).

  However, if the operator determines that there is a combustible material in the surrounding area and there is a risk of ignition and operates the regeneration prohibiting switch 38 to the ON position, the automatic regeneration stops (S13 → S14 → 16 → 21). Thereby, PM is continuously deposited.

  Further, when working indoors, the regeneration prohibiting switch 38 may be operated to the ON position in advance. In this case, even if the PM deposition amount exceeds the first threshold, automatic regeneration does not start, and PM is continuously deposited (S21 → S10 → S11 → S12 → S21).

  By the way, there is a close relationship between the engine output and the exhaust gas temperature. If the exhaust gas temperature is 250 degrees or higher during the operation, self-regeneration is performed and a part of the accumulated PM is burned and removed. However, even during work, the excavator is often in a non-operating state such as a standby time between processes. In the non-operation state, as the engine output decreases, the exhaust gas temperature also decreases, and there is a possibility that the exhaust gas temperature reaches about 100 ° C. When the exhaust gas temperature is less than 250 degrees, self-regeneration cannot be expected, and PM deposition further proceeds.

  The vehicle body controller 41 starts the temperature increase control when the regeneration prohibition is instructed, in the non-operation state, and the exhaust gas temperature is lower than 250 ° C. (S21 → S22 → S23 → S24). As the engine speed increases, the engine 1 is loaded and the exhaust gas temperature rises. Thereby, when self-regeneration is performed, a part of the deposited PM is burned and removed, and PM is continuously deposited, but the PM deposition progress can be reduced.

  When the exhaust gas temperature reaches 250 ° C. or higher, the vehicle body controller 41 stops the temperature increase control (S25 → S26). When the temperature raising control is stopped, the exhaust gas temperature gradually decreases, but if the exhaust gas temperature is 250 ° C. or higher, the temperature raising control is not performed (S21 → S22 → S23 → 22).

  Thereafter, when the excavator enters the operating state, the exhaust gas temperature is maintained at 250 ° C. or higher, and self-regeneration is performed.

  Note that the exhaust gas purification system of the present embodiment can mitigate the progress of PM deposition, but does not suppress the progress of PM deposition. Since forced regeneration is prohibited, when indoor work is continued, the PM accumulation amount eventually reaches a limit value (third threshold value), leading to DPF damage. In order to prevent DPF damage, a warning that “work is interrupted and forced regeneration is performed” is displayed on the display screen 6a before the PM accumulation amount reaches a limit value (third threshold value). In addition, the current PM deposition amount with respect to the limit value may be visually displayed. An estimated value of the remaining workable time may be displayed.

  The operator completes the work before the warning is displayed, or stops the work when the warning is displayed and moves the hydraulic excavator to an outdoor recyclable place. Then, the surrounding safety is confirmed, and the regeneration prohibiting switch 38 is operated to the OFF position. At this time, the PM accumulation amount is larger than the first threshold value, and automatic regeneration control is performed (S21 → S10 → S11 → S12 → S13 → S14 → S15 → S16). If automatic regeneration control is not performed, manual regeneration control may be performed. Thereby, DPF breakage can be prevented.

  After the reproduction is completed, the operator resumes the indoor work.

~effect~
The effect of the exhaust gas purification system of the first embodiment will be described. FIG. 8 is a diagram showing the passage of time of the PM accumulation amount shown for explaining the effect of the exhaust gas purification system of the first embodiment.

  As described above, when the regeneration prohibition switch 38 is operated to the ON position, the PM accumulation is continued because the forced regeneration is not performed. However, during the operation, if the exhaust gas temperature is moderate, self-regeneration is performed, and a part of the PM is incinerated and removed. However, even during work, when idling (during non-operation), the exhaust gas temperature may drop rapidly, and PM incineration removal by self-regeneration cannot be expected, and PM deposition further proceeds.

  If PM deposition continues, the PM deposition amount eventually reaches a limit value (third threshold value), and the possibility of DPF damage increases. FIG. 8 shows a virtual history when the temperature rise control is not performed by a broken line.

  In the present embodiment, the temperature rise control is started when the regeneration prohibiting switch 38 is in the ON position, in a non-operating state, and the exhaust gas temperature is less than 250 ° C. Thereby, when the exhaust gas temperature rises and self-regeneration is performed, a part of the deposited PM is burned and removed, and although PM is continuously deposited, the progress of PM deposition can be mitigated. FIG. 8 shows a history of temperature rise control with a solid line.

  By mitigating the progress of PM deposition, it is possible to extend the time until the amount of PM deposition reaches the limit value, and to secure working time. Since the operator completes the work within the work time and performs forced regeneration at a recyclable place, the DPF can be prevented from being damaged.

  Note that the exhaust gas temperature during self-regeneration (250 ° C. or higher) is lower than the exhaust gas temperature during forced regeneration (about 600 ° C.), and the risk of ignition is extremely low.

~ Modification ~
1. The exhaust gas purification system of the present embodiment includes an exhaust temperature detection device 37, and when the vehicle body controller 41 determines that the exhaust gas temperature is lower than the threshold value (step S23), it starts temperature increase control (step S24). However, this configuration can achieve an effect of improving fuel efficiency by avoiding unnecessary temperature rise, but is not an essential configuration.

  FIG. 9 is a flowchart showing the contents of the calculation process of the temperature rise control. The same processes as those in FIG. 6 are denoted by the same reference numerals. Also in this modified example, the effect of the present embodiment can be obtained that when the regeneration is prohibited, the DPF is prevented from being damaged and the working time can be secured.

  2. The process of step S24 of the engine controller 42, the electronic governor 1a of the engine 1 and the vehicle body controller 41 is performed when the non-operation state detecting means detects the non-operation state and the regeneration prohibiting means prohibits the operation of the forced regeneration device. The temperature raising means for raising the temperature of the gas is configured, but other configurations may be used.

  For example, the temperature increase control start in step S24 is performed as follows, for example.

FIG. 10 is a diagram showing the relationship between the discharge pressure / discharge flow rate of the hydraulic pump 11 and the output of the engine 1. The vehicle body controller 41 normally controls the pump discharge pressure P1 and the pump discharge flow rate Q1 to the minimum engine output PS1 from the viewpoint of energy saving when not in operation.

  The body controller 41 controls the discharge pressure of the pump 11 to the pump discharge pressure P2 (> P1) by controlling the amount of displacement of the control valve 30 during the temperature rise control. Further, the discharge flow rate of the hydraulic pump 11 is controlled to the pump discharge flow rate Q2 (> Q1) by controlling the tilt of the regulator 11a. As a result, since the hydraulic pump 11 is driven, the engine output PS2 is obtained, the load on the engine 1 is increased, and the exhaust gas temperature is increased.

  At this time, the engine speed may be increased. The temperature can be increased more reliably by increasing the engine speed and hydraulic load.

  3. The operation levers 28 and 29, the remote control valves 25 to 27, the shuttle valve group 46, the pressure sensor 47, the vehicle body and the process of step S22 of the controller 41 constitute a non-operation state detection means for detecting a non-operation state. It may be configured.

  The determination of whether or not in the non-operation state in step S22 is performed as follows, for example. When the gate lock lever 5 is raised to the second position B based on the detection signal of the position detection sensor 5a, that is, the vehicle body controller 41 is in a locked state in which the gate lock lever 5 blocks the control pilot pressure. The non-operation state may be determined. Further, the non-operation state may be determined based on both the detection signal of the pressure sensor 47 and the position detection sensor 5a.

<Second Embodiment>
~ Configuration / Control ~
In a working machine such as a hydraulic excavator, when the work machine is in a predetermined operating state for the purpose of reducing fuel consumption or noise, the engine speed is reduced below the speed indicated by the speed instruction device. Some perform control (engine speed reduction control). One example of such engine low speed control is auto idle control. In the auto idle control, the engine control dial 2 indicates the engine speed when a predetermined delay time has elapsed from the time when all of the operating levers 28 and 28 for instructing the operation of the driven body are in a neutral state. The idling speed is controlled to be lower than the rotating speed.

  When auto-idle control is started when regeneration is prohibited, the exhaust gas temperature decreases and self-regeneration cannot be expected, and PM deposition further proceeds. That is, the same problem as in the first embodiment occurs.

  FIG. 11 is a flowchart showing the contents of the calculation process of the temperature rise control when regeneration is prohibited by the vehicle body controller 41, which is a feature of the present embodiment.

  The vehicle body controller 41 first determines whether or not it is in a non-operating state (step S31), and if it is determined that it is not in a non-operating state (is in an operating state), the engine controller 41 based on an instruction signal from the engine control dial 3 A target rotational speed of 1 is set, and a command signal instructing the target rotational speed is output to the engine controller 42 (step S35).

  If it is determined in step S31 that the vehicle is in the non-operation state, auto idle control is started (step S32). Then, it is determined whether regeneration prohibition is commanded during auto idle control (step S33). If it is determined that regeneration prohibition is not commanded, auto idle control is continued.

  If it is determined in step S33 that the regeneration prohibition is instructed, the auto idle control is stopped (step S34).

~ Operation / Effects ~
During general work, normal engine speed control is performed (S31 → S35). On the other hand, when a non-operation state is detected, auto idle control is started (S31 → 32). At this time, when the regeneration prohibiting switch 38 is previously operated to the ON position, the auto idle control is invalidated. Further, when the regeneration prohibiting switch 38 is operated to the ON position after the start of the auto idle control, the auto idle control is stopped (S33 → S34). Then, normal engine speed control is performed (S31 → S35).

  When auto-idle control is started when regeneration is prohibited, the exhaust gas temperature decreases and self-regeneration cannot be expected, and PM deposition further proceeds. Thereby, the problem which concerns on working time or the problem which concerns on DPF breakage arises.

  In the present embodiment, when the regeneration prohibiting switch 38 is in the ON position and is in a non-operating state, the auto idle control is not performed, and the rotation speed indicated by the engine control dial 2 is maintained. As a result, when the exhaust gas temperature is maintained (temperature rise compared to that during auto-idle control) and self-regeneration is performed, a part of the accumulated PM is burned and removed, and PM continues to accumulate, but PM deposition proceeds. Can be relaxed.

  That is, the process of step S34 of the vehicle body controller 41 includes a temperature raising means for raising the temperature of the exhaust gas when the non-operation state detection means detects the non-operation state and the regeneration prohibiting means prohibits the operation of the forced regeneration device. Configure.

In this embodiment, the non-operation state of the auto idle control start condition is not distinguished from the non-operation state of the temperature increase control start (auto idle control stop) condition, but the non-operation of the operation levers 28 and 29 is continued. You may distinguish by time.

DESCRIPTION OF SYMBOLS 1 Diesel engine 1a Electronic governor 2 Engine control dial 3 Rotation speed detection device 4 Controller 5 Gate lock lever 5a Position detection sensor 6 Display device 6a Display screen 6b Operation 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 Main relief valve 23 Electromagnetic switching valve 24 Pilot oil passages 25, 26, 27 Remote control valves 28, 29 Operation lever 30 Control valve 31 Exhaust pipe 32 Filter 33 Oxidation catalyst 34 DPF device 36 Differential pressure detection device 37 Exhaust temperature detection device 38 Regeneration prohibition switch 39 Regeneration fuel injection device 41 Car body controller 42 Engine controller 43 Display controller 44 Communication line 46 Shuttle valve group 47 Pressure control Sensor 100 Lower traveling body 101 Upper revolving body 102 Front work machines 103a, 103b Crawler type traveling devices 104a, 104b Traveling motor 105 Turning motor 106 Engine room 107 Cabin 108 Driver's seat 111 Boom 112 Arm 113 Bucket 114 Boom cylinder 115 Arm cylinder 116 Bucket Cylinder

Claims (5)

It is mounted on a construction machine equipped with a diesel engine and a plurality of driven bodies driven by the power of this engine,
A filter disposed in the exhaust system of the engine for collecting particulate matter contained in the exhaust gas;
A forced regeneration device that regenerates the filter by incinerating and removing particulate matter deposited on the filter by injecting fuel into the exhaust system of the engine ;
When the amount of particulate matter deposited on the filter is greater than a first threshold value which is an automatic regeneration start value, the forced regeneration device is started to perform automatic regeneration control, and the particulate matter deposited on the filter is controlled. In an exhaust gas purification system including a regeneration control device that stops automatic regeneration control when the amount of accumulation becomes less than a second threshold value that is a regeneration end value ,
Non-operation state detection means for detecting non-operation states of the plurality of driven bodies;
Regeneration prohibiting means operable to an ON position and an OFF position, and prohibiting the operation of the forced regeneration device when operated to the ON position ;
The non-operation state detecting means detects the non-operation state, the when the reproduction inhibition means inhibits the operation of the forced regeneration apparatus, by applying a load to the engine increases the temperature of the exhaust gas, the deposited particulate An exhaust gas purification system for a construction machine, comprising: a temperature raising means for incinerating and removing substances by self-regeneration . The exhaust gas purification system according to claim 1,
An exhaust gas temperature detecting device for detecting the temperature of the exhaust gas;
The temperature raising means is further activated when the exhaust temperature detecting device detects a temperature lower than a threshold value. The exhaust gas purification system for a construction machine according to claim 1,
The exhaust gas purification system, wherein the temperature raising means applies a load to the engine by increasing the engine speed. The exhaust gas purification system for a construction machine according to claim 1,
The construction machine further includes a hydraulic circuit including a hydraulic pump driven by the engine and a hydraulic actuator driven by the discharge oil of the hydraulic pump to drive the driven body,
The exhaust gas purification system, wherein the temperature raising means is provided in the hydraulic circuit and applies a hydraulic load to the engine. The exhaust gas purification system for a construction machine according to claim 1,
The construction machine further includes auto idle control means for setting the engine speed to an idle speed when the non-operation state detection means detects a predetermined second non-operation state of the plurality of driven bodies,
The temperature raising means invalidates the auto idle control and maintains the engine speed.

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