JP5714300B2 - 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 Therefore, there is a technique called forced regeneration in which the exhaust gas temperature is forcibly increased to a temperature higher than the activation temperature of the oxidation catalyst. 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.

  In automatic regeneration, a regeneration prohibiting means is provided, and automatic regeneration is prohibited by operating the regeneration prohibiting means at the operator's discretion, and the work vehicle is moved to a place where there is no flammable material (recyclable place) to ensure safety. To cancel playback prohibition and resume automatic playback.

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

  For example, there may be a case where a long distance movement to a recyclable place is required, such as work at a tunnel site. Further PM accumulates while the work vehicle is moved to a recyclable location. When the exhaust gas purification system determines that the PM accumulation amount has exceeded the limit value, both automatic regeneration and manual regeneration are prohibited in order to prevent the filter from damaging due to abnormal combustion. That is, there may be a situation where the operator cannot manually regenerate and cannot move the work vehicle. In this case, the operator has to ask for maintenance, which hinders the subsequent work.

  In response to such a problem, the applicant of the present application, in the prior application, when the automatic regeneration control is prohibited, the exhaust gas purification that additionally displays that the regeneration is prohibited, the PM accumulation amount screen, and the estimated remaining usable time A system has been proposed (Japanese Patent Application No. 2009-184714). The operator predicts the time until the PM accumulation amount reaches the limit value while looking at the display screen, makes an appropriate work plan, and corrects the work plan as needed. Thus, before the PM accumulation amount reaches the limit value, the operator can move the work vehicle to a recyclable place.

  However, this prior art does not extend the time until the PM deposition amount reaches the limit value. If the work plan set by the operator is inappropriate, the PM accumulation amount may reach a limit value before the work vehicle is moved to a recyclable place.

An object of the present invention is to provide an exhaust gas purification system for a work vehicle that can extend the time until the PM accumulation amount reaches a limit value.

(1) In order to achieve the above object, the present invention provides a diesel engine, a filter that is disposed in an exhaust system of the engine and collects particulate matter contained in exhaust gas, and particles deposited on the filter. the Jo material was burned and removed by fuel injection, a reproducing means for reproducing the filter, the exhaust gas cleaning system for a working vehicle and a control means for controlling the rotational speed and the torque of the engine, operation of the regeneration means A manual regeneration switch for instructing start, and a regeneration inhibition switch for instructing prohibition of the operation of the regeneration means, and the control means is configured to control the particulate matter deposited on the filter based on the pressure loss of the filter. When the accumulation amount estimation function for estimating the accumulation amount and the estimated accumulation amount estimated by the accumulation amount estimation function exceed the first threshold, the regeneration means is operated. When the automatic regeneration control function and the estimated accumulation amount are greater than a second threshold value that is greater than the first threshold value, a warning signal that prompts operation of the manual regeneration switch is output, and when the manual regeneration switch is operated, the regeneration means When the regeneration prohibiting switch is operated while the regeneration means is inactive, the regeneration means by the automatic regeneration control function and the manual regeneration control function is not started. The regeneration prohibiting control function for prohibiting the operation of the reproducing means by prohibiting the operation of the reproducing means by prohibiting the operation of the reproducing means and stopping the operation of the reproducing means when the regeneration prohibiting switch is operated during the operation of the reproducing means. When a normal mode for selecting a first operation point that is a combination of the first rotational speed and first torque set in terms of the vehicle body operability and fuel consumption, exhaust gas A particulate second rotational speed that is set in terms of emissions reduction of material and the mode switching function for switching between particulate matter emissions reduction mode for selecting a second operating point is a combination of the second torque contained in have a, the mode switching function, the when the reproduction inhibition switch is operated, it is assumed that the switching from simultaneously the normal mode when prohibiting the operation of said reproducing means to said particulate matter emissions reduction mode.

  As described above, the mode switching function switches from the normal mode to the particulate matter emission reduction mode, and the engine operating point shifts from the first point to the second point where the particulate matter emission amount is smaller than the first operation point. The amount of particulate matter discharged can be reduced, and the time until the amount of particulate matter deposited reaches the limit value can be extended.

Further , the particulate matter discharge amount can be reduced semi-automatically with the operation of the regeneration prohibiting means.

( 2 ) In the above (1), preferably, the mode switching function has a map for setting the second operation point.

  Thereby, based on the map, it is possible to select the second point having a smaller particulate matter discharge amount than the first operation point.

( 3 ) In the above (1), preferably, the first operation point and the second operation point are on the same equal horsepower line.

As a result, the influence on operability and fuel consumption is less than in the case of not being on the equal horsepower line.
( 4 ) In the above (1), preferably, the mode switching function is created by plotting a particulate matter emission index value for each operating point which is a combination of the engine speed and torque, and adds a constant horsepower line. And when switching from the normal mode to the particulate matter emission reduction mode, the combination of the engine speed and torque on the same equihorse force line of the particulate matter discharge map is changed to the second Select as operating point.
This makes it possible to select the second point having a smaller particulate matter discharge amount than the first operation point based on the map while reducing the influence on operability and fuel consumption.

  According to the present invention, the time until the PM deposition amount reaches the limit value can be extended. Thereby, a work vehicle can be reliably moved to a recyclable place.

1 is a diagram illustrating an overall configuration of an exhaust gas purification system (first embodiment). FIG. It is a figure which shows the detail of the control apparatus. It is a figure which shows the external appearance of a hydraulic shovel. 4 is a flowchart showing the contents of calculation processing of a regeneration control function 41a of the vehicle body control device 41. It is a figure which shows the relationship between the pressure loss (DELTA) P (front-back differential pressure) of the filter 32, and the deposition amount W of PM. 4 is a flowchart showing the contents of calculation processing of a mode switching function 41b of the vehicle body control device 41. It is an example of PM discharge map. It is a figure explaining an example of switching control from normal mode to PM discharge amount reduction mode. It is a figure which shows the time passage of PM deposition amount. It is a flowchart which shows the content of the arithmetic processing of the mode switching function 41b ( reference example 1 ). It is a PM discharge mode setting screen 6c displayed on the display device 6. It is a flowchart which shows the content of the arithmetic processing of the mode switching function 41b ( reference example 2 ). It is a figure which shows the time passage of PM deposition amount.

<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 according to the first embodiment.

  In FIG. 1, the working vehicle according to the present embodiment is, for example, a hydraulic excavator, and this hydraulic excavator includes a diesel engine (hereinafter simply referred to as an engine) 1 having an electronic governor 1a (an electronically controlled fuel injection control device). Have. The target engine speed of the engine 1 is commanded by the engine control dial 2 provided in the cabin (operator's cab) 107 (see FIG. 4) of the hydraulic excavator, and the actual engine speed of the engine 1 is detected by the engine speed detector 3. The The command signal of the engine control dial 2 and the detection signal of the rotation speed detection device 3 are input to the control device 4, and the control device 4 is based on the command signal (target rotation speed) and the detection signal (actual rotation speed). 1a is controlled, and the rotation speed and torque of the engine 1 are controlled.

  The exhaust gas purification system is mounted on the above-described work vehicle (hydraulic excavator) and is disposed in the exhaust pipe 31 constituting the exhaust system of the engine 1 to collect particulate matter (PM) contained in the exhaust gas. The filter 32 and the DPF device 34 including the oxidation catalyst 33 disposed on the upstream side of the filter 32, the exhaust gas temperature detection device 35, and the pressure loss of the filter 32 (the differential pressure between the upstream side and the downstream side of the filter 32) are detected. And a regeneration regeneration switch 37, a regeneration inhibition switch 38, and a regeneration fuel injection device 39 provided between the engine 1 of the exhaust pipe 31 and the DPF device 34.

  The regeneration fuel injection device 39 constitutes a regeneration means for the filter 32 that raises the temperature of the exhaust gas and incinerates and removes PM accumulated on the filter 32. The manual regeneration switch 37 and the regeneration prohibition switch 38 are arranged at positions in the hydraulic excavator cabin 107 where the operator can easily operate. The manual regeneration switch 37 is an operating means for instructing the start of operation of the regeneration fuel injection device 39 (regeneration control start of the filter 32), and a command for instructing the start of regeneration control when the manual regeneration switch 37 is operated to the ON position. A signal is output. The regeneration prohibiting switch 38 is an operating means for instructing prohibition of the operation of the fuel injection device 39 for regeneration (prohibiting regeneration control of the filter 32). A signal is output.

  The manual regeneration switch 37 and the regeneration prohibition switch 38 may be a setting screen displayed on the display device 6 (described later). The operation switch 6b is operated to set ON / OFF.

  The control device 4 receives command signals from the manual regeneration switch 37 and the regeneration prohibition switch 38, and these command signals, a detection signal from the differential pressure detection device 36, a command signal from the engine control dial 2 and the rotation speed. Based on the detection signal of the detection device 3, a calculation process of regeneration control is performed, and the electronic governor 1a and the regeneration fuel injection device 39 are controlled according to the calculation result. Further, the control device 4 uses the information indicated by various signals from the rotation speed detection device 3, the differential pressure detection device 36, the manual regeneration switch 37, and the regeneration prohibition switch 38 and the calculation processing result of the regeneration control of the control device 4 as display signals. The information is sent to the display device 6 and displayed on the display screen 6a.

  The display device 6 is disposed at a position in the hydraulic excavator cabin 107 where the operator can easily see, and originally displays basic information of the hydraulic excavator body such as the remaining fuel amount and the coolant temperature. The display device 6 includes a display screen 6a and operation switches 6b, and is controlled by a display control device 42 (described later) of the control device 4. The operation switch 6b is arranged on the lower side of the display screen 6a, and vehicle information other than the vehicle body basic information is selectively displayed by operating the operation switch 6b. In addition, information related to reproduction, such as a warning for prompting an operation of the manual regeneration switch 37, indicating that automatic regeneration control is being performed, is also displayed as appropriate.

  FIG. 2 is a diagram showing details of the control device 4. The control device 4 includes a vehicle body control device 41 including a regeneration control function 41a and a mode switching function 41b, a display control device 42, and an engine control device 43. These control devices 41 to 43 are connected via a communication line 44. They are connected to each other to form a vehicle body network. The command signal from the engine control dial 2, the detection signal from the differential pressure detection device 36, the command signal from the manual regeneration switch 37 and the regeneration prohibition switch 38 are input to the vehicle body control device 41, and the detection signal from the rotational speed detection device 3 is engine control. Input to the device 43.

  The engine control device 43 receives the command signal of the engine control dial 2 via the communication line 44, and based on the command signal and the detection signal of the rotation speed detection device 3, the engine speed and torque of the engine 1 are obtained as described above. Control. Details of the control will be described later.

  The vehicle body control device 41 controls the entire hydraulic system (not shown) of the hydraulic excavator. For example, the vehicle body control device 41 detects the operation amount of the operation lever and discharges a flow rate corresponding to the operation amount. Control the tilt angle (capacity). Further, the vehicle body control device 41 has a regeneration control function 41a. The regeneration control function 41a estimates the PM accumulation amount accumulated on the filter 32 based on the detection signal (pressure loss) of the differential pressure detection device 36, and performs communication. Based on the detection signal of the rotational speed detection device 3 received via the line 44, the command signal of the engine control dial 2, the command signal from the manual regeneration switch 37 and the regeneration prohibiting switch 38, the regeneration control is processed. A control signal corresponding to the result is transmitted to the engine control device 43 via the communication line 44, and the engine control device 43 controls the electronic governor 1a and the regeneration fuel injection device 39 according to the control signal.

  The mode switching function 41b, which is a characteristic configuration of the present embodiment, is a function of the vehicle body control device 41, and selects an operating point that is an optimal combination of engine speed and torque according to the situation, and the result is used as a communication line. And transmitted to the engine control device 43 via 44. Details of the control will be described later.

  The display control device 42 receives various signals from the rotation speed detection device 3, the differential pressure detection device 36, the manual regeneration switch 37, and the regeneration prohibition switch 38 and the calculation processing result of the forced regeneration control via the communication line 44, and As described above, the signal information and the calculation processing result are sent to the display device 6 as display signals, and the information is displayed on the display screen 6a.

  FIG. 3 is an external view of a hydraulic excavator that is an example of a work vehicle. 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 cab) 107. The engine 1 is disposed in the engine room 106, and an engine control dial 2, a display device 6, a manual regeneration switch 37, A regeneration prohibiting switch 38 is provided.

  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.

  The work vehicle may be a wheel loader or a wheeled hydraulic excavator.

~control~
<Playback control>
FIG. 4 is a flowchart showing the contents of the calculation process of the regeneration control function 41a of the vehicle body control device 41. The regeneration control function 41a has an automatic regeneration control function and a manual regeneration control function.

  In FIG. 4, the reproduction control function 41a first determines whether or not the reproduction prohibition switch 38 has been operated (reproduction prohibition switch ON) (step S100), and the reproduction prohibition switch 38 has not been operated (reproduction prohibition switch OFF). ), 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 second threshold that is a manual regeneration start value (step S110), and the estimated accumulation amount is larger than the second threshold. If it is determined that there is not, it is determined whether or not the estimated accumulation amount is larger than a first threshold value which is an automatic regeneration start value (step S120).

  If it is determined in step S120 that the estimated accumulation amount is not larger than the first threshold value, the procedure returns to the procedure immediately after the start and the regeneration prohibiting switch 38 is operated or the estimated accumulation amount is larger than the first threshold value or the second threshold value. , Steps S100, S110, and S120 are repeated.

  If it is determined in step S120 that the estimated accumulation amount is larger than the first threshold, automatic regeneration control is started (step S130). During automatic regeneration control, it is determined whether or not the regeneration prohibition switch 38 has been operated (regeneration prohibition switch ON) (step S140), and if it is determined that the regeneration prohibition switch 38 has not been operated (regeneration prohibition switch OFF), it is estimated. It is determined whether or not the accumulation amount is less than the fourth threshold value that is the regeneration end value (step S150). If it is determined that the estimated accumulation amount is less than the fourth threshold value, the automatic regeneration control is stopped (step S160), and the calculation is performed. The process ends (step S170). If it is determined in step S150 that the estimated accumulation amount is not smaller than the fourth threshold value, the processes of steps S140 and S150 are repeated until the regeneration prohibiting switch 38 is operated or the estimated accumulation amount becomes smaller than the fourth threshold value.

  If it is determined in step S110 that the estimated accumulation amount is greater than the second threshold value, a warning signal that prompts the operator to operate the manual regeneration switch 37 is output (step S210). Note that the display control device 42 inputs a warning signal via the communication line 44 and displays a warning for prompting manual regeneration on the display screen 6a.

  It is determined whether or not the manual regeneration switch 37 has been operated (regeneration start switch ON) (step S220). If it is determined that the manual regeneration switch 37 has not been operated (regeneration start switch OFF), the procedure returns to the procedure immediately after the start. Steps S100, S110, S210, and S220 are repeated until the manual regeneration switch 37 is operated. That is, a warning is displayed until the manual regeneration switch 37 is operated.

  If it is determined in step S220 that the manual regeneration switch 37 has been operated (regeneration start switch ON), manual regeneration control is started (step S230). During manual regeneration control, it is determined whether or not the regeneration prohibition switch 38 has been operated (regeneration prohibition switch ON) (step S240), and if it is determined that the regeneration prohibition switch 38 has not been operated (regeneration prohibition switch OFF), it is estimated. It is determined whether or not the accumulation amount is smaller than the fourth threshold value that is the regeneration end value (step S250). When it is determined that the estimated accumulation amount is smaller than the fourth threshold value, the manual regeneration control is stopped (step S260), and the calculation is performed. The process ends (step S170). If it is determined in step S250 that the estimated accumulation amount is not smaller than the fourth threshold value, the processes of steps S240 and S250 are repeated until the regeneration prohibiting switch 38 is operated or the estimated accumulation amount becomes smaller than the fourth threshold value.

  If it is determined in step S100 that the regeneration prohibition switch 38 has been operated (regeneration prohibition switch ON), the arithmetic processing is terminated (step S170). If it is determined in step 140 that the regeneration prohibiting switch 38 has been operated during the automatic regeneration control (reproduction prohibiting switch ON), the automatic regeneration control is stopped (step S160), and the arithmetic processing is terminated (step S170). If it is determined in step 240 that the regeneration prohibition switch 38 has been operated during the manual regeneration control (regeneration prohibition switch ON), the manual regeneration control is stopped (step S260), and the calculation process is terminated (step S170).

  In step S150 and step S250, the regeneration control function 41a determines whether or not the estimated accumulation amount based on the detection signal of the differential pressure detection device 36 has become smaller than the fourth threshold, and ends the regeneration control. It may be determined whether the playback control time has passed a predetermined time and the playback control may be terminated.

  The automatic regeneration control in step S130 and the manual regeneration control in step S230 are 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 control device 41 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 The number of revolutions) is transmitted to the engine control device 43 via the communication line 44. The engine control device 43 feedback-controls the fuel injection amount of the electronic governor 1a 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, and the engine 1 The number of rotations is controlled to the predetermined number of rotations Na.

  Next, when it is confirmed that the exhaust gas temperature detected by the exhaust temperature detection device 35 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 the forced regeneration control is stopped in step S160 and step S260, 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. 5 is a graph showing the relationship between the pressure loss ΔP (front / rear differential pressure) of the filter 32 and the PM deposition amount W. As shown in FIG. The relationship between the pressure loss ΔP and the PM deposition amount W is determined in advance based on experimental data. In FIG. 5, for convenience, the relationship between the pressure loss ΔP and the PM deposition amount W is shown in a linear proportion, but the actual relationship between the pressure loss ΔP and the PM deposition amount W is not a linear proportion. The amount of PM deposited on the filter 32 is estimated based on the pressure loss by the differential pressure detector 36. When PM is not deposited on the filter 32, there is no pressure loss due to the effect of PM deposition, the pressure loss ΔP is ΔP0, and as the PM is deposited on the filter 32 and the deposition amount W increases, the differential pressure ΔP is increased. To rise.

  The first threshold value is a value corresponding to the accumulation amount at which automatic regeneration control is to be started. The second threshold value is a value corresponding to the accumulation amount that should prompt the operator to perform manual regeneration control. The third threshold value is a reproducible upper limit value (limit value). In other words, if PM is burned in a state where PM has accumulated more than the third threshold, problems such as abnormal rise in the internal temperature of the filter and melting of the filter resulting from it may occur, so automatic regeneration control, manual regeneration Both control is stopped. The fourth threshold value is a value corresponding to the accumulation amount that can be regarded as having been completed for both automatic regeneration control and manual regeneration control.

  A relationship between the reproduction control and the threshold will be described. The second threshold is set larger than the first threshold, and automatic regeneration control is performed with priority over manual regeneration control. However, there are cases where PM cannot be burned and removed satisfactorily even by automatic regeneration control due to various factors, and PM is further deposited. When the accumulation amount exceeds the second threshold value, manual regeneration control is performed. However, when the accumulation amount exceeds the third threshold, neither automatic regeneration control nor manual regeneration control is performed. When the PM can be burned and removed satisfactorily and the accumulation amount becomes less than the fourth threshold value, both the automatic regeneration control and the manual regeneration control are finished.

<Mode switching control>
FIG. 6 is a flowchart showing the contents of the arithmetic processing of the mode switching function 41b of the vehicle body control device 41.

  The mode switching function 41b sets the normal mode at the normal time (step S310).

  The normal mode will be described. The target rotational speed of the engine 1 is commanded by the engine control dial 2, and an optimum torque is calculated at this rotational speed from the viewpoint of operability and fuel consumption. When the engine is idling, the engine 1 is switched to a low speed idling speed, and during regeneration control, the engine speed is switched to a medium speed Na, and an optimum torque is calculated at this speed from the viewpoint of operability and fuel consumption. A control signal corresponding to the calculation result is transmitted to the engine control device 43 via the communication line 44, and the engine control device 43 controls the electronic governor 1a according to the control signal.

  In the normal mode of step S310, it is determined whether or not the regeneration prohibition switch 38 is in the ON position (step S320). If it is determined that the regeneration prohibition switch 38 is in the ON position, the PM emission reduction mode is set (step S330). ). When it is determined that the regeneration prohibiting switch 38 is not in the ON position, the normal mode is maintained.

  The PM emission reduction mode will be described.

  FIG. 7 is an example of a PM discharge map included in the mode switching function 41b. The PM emission map is a contour diagram in which PM emission index values are plotted on the basis of experimental results for each operation point that is a combination of the engine speed and torque within the entire load line. The PM emission amount index value is determined based on the smoke permeability of the exhaust gas. When the index value increases, it means that the PM emission amount increases, and when the index value decreases, it means that the PM emission amount decreases. L1 is the smallest index value, and L4 is the largest index value. Equivalent lines are indicated by dotted lines, and are divided into levels L1 to L4.

  As described above, in the normal mode, the operation point is selected from the viewpoint of operability and fuel consumption, and the viewpoint of the amount of PM emission is not taken into consideration. There is a possibility that the PM discharge amount at the first operation point selected in the normal mode is larger than the PM discharge amount at other operation points. In that case, in the PM emission amount reduction mode, based on the PM emission map, an operation point having a PM emission amount smaller than the first operation point is selected as the second operation point.

  FIG. 8 is a diagram for explaining an example of switching control from the normal mode to the PM emission reduction mode of the mode switching function 41b, and is a part of the PM emission map shown in FIG. To the enlarged view of the PM emission map, equal horsepower lines HP01 to 04 indicated by broken lines are added, and the plot is omitted for the sake of simplicity. In this example, in the normal mode, from the viewpoint of operability and fuel consumption, the first operating point at which the engine speed N1 and the torque T1 are selected is selected. The index value of the PM emission amount at the first operating point is L3. When the mode is switched to the PM emission reduction mode, the second operation point (engine speed N2 (<N1), torque T2) is on the same horsepower line HP03 as the first operation point and the PM emission index value is L2. (> T1)) is selected.

  The mode switching function 41b transmits a control signal related to the second operation point to the engine control device 43 via the communication line 44, and the engine control device 43 controls the electronic governor 1a according to the control signal.

  In the PM emission reduction mode in step S330, it is determined whether or not the regeneration prohibition switch 38 is in the OFF position (step S340). If it is determined that the regeneration prohibition switch 38 is in the OFF position, the normal mode is restored (step S310). . When it is determined that the regeneration prohibiting switch 38 is not in the OFF position, the PM emission amount reduction mode is maintained.

~ Operation ~
The operation of the exhaust gas purification system of the first embodiment will be described. For example, assume work at a tunnel site.

  During the work at the tunnel site, dust and the like are easily generated, 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, automatic regeneration is started (S100 → S110 → S120 → S130).

  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, automatic regeneration is stopped (S140 → S160).

  At this time, the mode switching function 41b switches from the normal mode to the PM emission reduction mode (S310 → S320 → S330). Since the regeneration is not performed, the PM deposition is continued, but the PM emission amount is reduced. Thereby, time until PM deposition amount reaches a limit value can be extended.

  The operator completes the minimum work or immediately finishes and moves the excavator to a recyclable location outside the tunnel. When the surrounding safety is confirmed and the regeneration prohibiting switch 38 is operated to the OFF position, the mode switching function 41b returns from the PM emission reduction mode to the normal mode (S330 → S340 → S310).

  At this time, there is a high possibility that the PM accumulation amount is larger than the first threshold value, and automatic regeneration is resumed (S100 → S110 → S120 → S130). When the good regeneration is performed and the PM accumulation amount becomes less than the fourth threshold value, the automatic regeneration ends (S140 → S150 → S160).

  After the regeneration is completed, the operator resumes the work at the tunnel site.

~effect~
The effect of the exhaust gas purification system of the first embodiment will be described. FIG. 9 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 prohibiting switch 38 is operated to the ON position, regeneration is not performed, so PM deposition continues. Here, it is assumed that the mode switching function 41b maintains the normal mode. In the normal mode, the first operation point is selected from the viewpoint of operability and fuel consumption, and the viewpoint of the amount of PM emission is not considered. In the example of FIG. 8, the index value of the PM emission amount at the first operating point is L3. When PM deposition continues, the PM deposition amount eventually reaches a limit value (third threshold value). The virtual history at this time is indicated by a broken line. If the virtual arrival time is early, the virtual arrival time is reached while the excavator is moving, and the excavator cannot be moved to a recyclable location.

  In the present embodiment, when the regeneration prohibiting switch 38 is operated to the ON position, the normal mode is switched to the PM emission reduction mode. The second operation point is selected in the PM emission reduction mode, and the index value of the PM emission is L2 in the example of FIG. For convenience of explanation, assuming that the index value is proportional to the PM emission amount, the PM emission amount is reduced by approximately 30% (L3 → L2), and the time until the PM accumulation amount reaches the limit value (third threshold) is set. Can be extended. The history at this time is indicated by a solid line.

  In the PM emission reduction mode, there is a possibility that it is not preferable from the viewpoint of operability and fuel consumption, but it is only while moving from a work site such as a tunnel to a recyclable place, and its influence is limited.

  In addition, since the first operation point and the second operation point are on the same equal horsepower line HP03, the influence on the operability and fuel consumption is less than that when not on the equal horsepower line.

~ Modification ~
In the operation of the present embodiment, it is preferable that the first operation point and the second operation point are on the same equal horsepower line, but even when the first operation point and the second operation point are not on the equal horsepower line, the time until the PM accumulation amount reaches the limit value is extended. it can.

<Reference Example 1>
~control~
In the first embodiment, the mode switching function 41b switches from the normal mode to the PM emission reduction mode semi-manually (semi-automatically) when the regeneration prohibiting switch 38 is operated to the ON position. If the threshold value exceeds 2, the normal mode may be automatically switched to the PM emission reduction mode.

  FIG. 10 is a flowchart showing the contents of the arithmetic processing of the mode switching function 41b.

  The mode switching function 41b sets the normal mode during normal operation (step S310), determines whether the PM accumulation amount is larger than the second threshold value in the normal mode (step S320A), and the PM accumulation amount is larger than the second threshold value. If determined, the PM emission reduction mode is set (step S330). When it is determined that the PM accumulation amount is not greater than the second threshold, the normal mode is maintained.

  In the PM emission reduction mode, it is determined whether or not the manual regeneration switch 37 is in the ON position (step S340). If it is determined that the manual regeneration switch 37 is in the ON position, the normal mode is restored (step S310). When it is determined that the manual regeneration switch 37 is not ON, the PM emission amount reduction mode is maintained.

~ Operation ~
The operation of the exhaust gas purification system of Reference Example 1 will be described.

  During the work at the tunnel site, dust and the like are easily generated, and PM accumulates on the filter. If the amount of accumulated PM exceeds the second threshold because automatic regeneration is prohibited or good automatic regeneration is not performed, a warning that prompts manual regeneration is issued. (S100 → S110 → S210).

  However, manual regeneration does not start unless the operator determines that there is a combustible material around and there is a risk of ignition and the manual regeneration switch 37 is not operated to the ON position.

  At this time, the mode switching function 41b switches from the normal mode to the PM emission reduction mode (S310 → S320A → S330). Since the regeneration is not performed, the PM deposition is continued, but the PM emission amount is reduced. Thereby, time until PM deposition amount reaches a limit value can be extended.

  The operator completes the minimum work or immediately finishes and moves the excavator to a recyclable location outside the tunnel. When the surrounding safety is confirmed and the manual regeneration switch 37 is operated to the ON position, the mode switching function 41b returns from the PM emission reduction mode to the normal mode (S330 → S340 → S310).

  At the same time, manual regeneration starts (S220 → S230). When the good regeneration is performed and the PM accumulation amount becomes smaller than the fourth threshold value, the manual regeneration is finished (S240 → S250 → S260).

  After the regeneration is completed, the operator resumes the work at the tunnel site.

~effect~
The effect of the exhaust gas purification system of Reference Example 1 will be described.

  As described above, even if the PM accumulation amount exceeds the second threshold and a warning for prompting manual regeneration is issued, regeneration is not performed unless the manual regeneration switch 37 is operated to the ON position, so PM deposition continues. . Here, it is assumed that the mode switching function 41b maintains the normal mode. Eventually, the PM accumulation amount reaches the limit value (third threshold value), but if the first operating point with a large PM emission index value is selected and the virtual arrival time is early, the excavator can be moved to a recyclable location. Can not.

In this reference example , when the PM accumulation amount exceeds the second threshold value, the normal mode is switched to the PM discharge amount reduction mode. In the PM emission reduction mode, the second operation point having a small PM emission index value is selected, the PM emission is reduced, and the time until the PM accumulation reaches the limit value can be extended.

~ Modification ~
In this reference example , as an example, the switching control is performed when the PM accumulation amount exceeds the second threshold value. However, the threshold value can be arbitrarily set as long as the threshold value is equal to or less than the third threshold value. For example, if the switching control is performed when the PM accumulation amount exceeds the first threshold, the time until the PM accumulation amount reaches the limit value can be further extended.

<Reference example 2>
~ Configuration and control ~
The mode switching function 41b performs semi-manual (semi-automatic) switching control in the first embodiment, and performs automatic switching control in Reference Example 1. However, even if manual switching control based on an operator's judgment is performed. Good.

As a mode switching operation means, a mode switching switch similar to the manual regeneration switch 37 or the regeneration prohibiting switch 38 may be provided at a position where the operator within the cabin 107 of the excavator can easily operate. In this reference example , FIG. The PM discharge mode is set on the PM discharge mode setting screen 6c displayed on the display device 6 shown. The PM discharge mode setting screen 6c includes a “normal mode” item and a “PM discharge amount reduction mode” item, and each item can be selected by operating the up and down buttons of the operation switch 6b.

  FIG. 12 is a flowchart showing the contents of calculation processing of the mode switching function 41b.

  The mode switching function 41b sets the normal mode during normal operation (step S310), determines whether the “PM emission reduction mode” item has been selected in the normal mode (step S320B), and “PM emission reduction mode”. If it is determined that the item has been selected, a PM emission reduction mode is set (step S330). If it is determined that the “PM emission reduction mode” item is not selected, the normal mode is maintained.

  In the PM emission reduction mode, it is determined whether or not the “normal mode” item has been selected (step S340B). If it is determined that the “normal mode” item has been selected, the mode returns to the normal mode (step S310). When it is determined that the “normal mode” item is not selected, the PM emission amount reduction mode is maintained.

~ Operation ~
The operation of the exhaust gas purification system of Reference Example 2 will be described.

  When carrying wood chips indoors, dust and the like are likely to be generated, and PM is likely to accumulate on the filter. On the other hand, there are cases where the work area is extremely narrow, there are combustibles around the area, there is a risk of ignition, and it is not preferable to perform the regeneration itself. Prohibiting regeneration by the regeneration prohibiting switch 38 is also an effective means, but as soon as the regeneration is prohibited, the PM accumulation amount reaches the limit value.

  In such a work environment, the operator sets the PM discharge amount reduction mode via the PM discharge mode setting screen 6c before starting the indoor work. The mode switching function 41b switches from the normal mode to the PM emission reduction mode (S310 → S320B → S330).

  In the PM emission reduction mode, since the PM emission is reduced as compared with the normal mode, the PM accumulation is also reduced. If the PM accumulation amount does not reach the first threshold value, automatic regeneration does not start (S100 → S110 → S120 → S100).

  The operator completes a predetermined work before the automatic regeneration starts, and moves the hydraulic excavator to an outdoor recyclable place. When the normal mode is set via the PM discharge mode setting screen 6c, the mode switching function 41b returns from the PM discharge amount reduction mode to the normal mode (S330 → S340B → S310).

  Thereafter, in the normal mode, when outdoor work is performed and the PM accumulation amount exceeds the first threshold value, automatic regeneration starts (S100 → S110 → S120 → S130), and good regeneration is performed and the PM accumulation amount is increased. When it becomes less than the fourth threshold, the automatic reproduction ends (S140 → S150 → S160).

~effect~
The effect of the exhaust gas purification system of Reference Example 2 will be described. FIG. 13 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 Reference Example 2 .

  The mode switching function 41b assumes that the normal mode is maintained. In the normal mode, the first operation point having a large PM emission index value is selected. When PM accumulates and exceeds the first threshold, automatic regeneration starts. The virtual history at this time is indicated by a broken line. If the virtual automatic regeneration start time is early, the hydraulic excavator becomes the virtual automatic regeneration start time during indoor work, and sufficient indoor work time cannot be secured.

In this reference example , the PM emission amount reduction mode is set via the PM emission mode setting screen 6c before indoor work. In the PM emission reduction mode, the second operation point having a small PM emission index value is selected, the PM emission is reduced, and the time until the PM accumulation reaches the first threshold can be extended. The history at this time is indicated by a solid line.

  Thereby, a sufficient indoor working time can be secured, and the work can be completed before the automatic regeneration starts.

DESCRIPTION OF SYMBOLS 1 Diesel engine 1a Electronic governor 2 Engine control dial 3 Rotational speed detection device 4 Control device 6 Display device 6a Display screen 6b Operation switch 6c PM discharge mode setting screen 31 Exhaust pipe 32 Filter 33 Oxidation catalyst 34 DPF device 35 Exhaust temperature detection device 36 Differential pressure detection device 37 Manual regeneration switch 38 Regeneration prohibition switch 39 Regeneration fuel injection device 41 Car body control device 41a Regeneration control function 41b Mode switching function 42 Display control device 43 Engine control device 44 Communication line 100 Lower traveling body 101 Upper turning body 102 Front work machines 103a and 103b Crawler type traveling devices 104a and 104b Traveling motor 105 Turning motor 106 Engine room 107 Driver's cab 108 Driver's seat 111 Boom 112 Arm 113 Bucket 114 Boom cylinder 11 5 Arm cylinder 116 Bucket cylinder

Claims (4)

A diesel engine,
A filter disposed in the exhaust system of the engine for collecting particulate matter contained in the exhaust gas;
Reproducing means for the deposited particulate matter in the filter to burn removed by fuel injection, to play this filter,
In an exhaust gas purification system for a work vehicle comprising control means for controlling the engine speed and torque,
A manual regeneration switch for instructing the start of operation of the regeneration means;
A regeneration prohibiting switch for instructing prohibition of the operation of the regeneration means,
The control means includes
Based on the pressure loss of the filter, when the deposition amount estimation function for estimating the deposition amount of the particulate matter deposited on the filter and the estimated deposition amount estimated by the deposition amount estimation function are greater than a first threshold, An automatic regeneration control function for activating the regeneration means;
When the estimated accumulation amount exceeds a second threshold value that is greater than the first threshold value, a warning signal that prompts operation of the manual regeneration switch is output, and when the manual regeneration switch is operated, manual regeneration control that activates the regeneration unit is performed. Function and
When the regeneration prohibiting switch is operated while the regeneration means is not in operation, the regeneration means is prohibited from starting by the automatic regeneration control function and the manual regeneration control function, thereby prohibiting the operation of the regeneration means. A regeneration prohibiting control function for prohibiting the operation of the regeneration means by stopping the operation of the regeneration means when the regeneration prohibiting switch is operated during the operation of the regeneration means;
Viewpoint of the normal mode and emissions reduction of particulate matter contained in exhaust gas of selecting a first rotational speed and first operating point is a combination of a first torque set in terms of the vehicle body operability and fuel economy have a second rotational speed and the particulate emissions reduction mode for selecting a second operating point is a combination of the second torque and the mode switching function for switching the set from,
The mode switching function, the when the reproduction inhibition switch is operated, the exhaust gas of the work vehicle, characterized in that switching from simultaneously the normal mode when prohibiting the operation of said reproducing means to said particulate matter emissions reduction mode Purification system. The exhaust gas purification system for a work vehicle according to claim 1,
The mode switching function includes a map for setting the second operating point, and an exhaust gas purification system for a work vehicle . The exhaust gas purification system for a work vehicle according to claim 1,
The exhaust gas purification system for a work vehicle, wherein the first operation point and the second operation point are on the same equihorse force line. The exhaust gas purification system for a work vehicle according to claim 1,
The mode switching function has a particulate matter emission map created by plotting particulate matter emission index values for each operating point that is a combination of engine speed and torque, and added with a constant horsepower line. When switching from the mode to the particulate matter emission reduction mode, a work vehicle that selects a combination of engine speed and torque that are on the same equihorse force line of the particulate matter discharge map as the second operation point. Exhaust gas purification system.

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