JP5471834B2 - Exhaust gas purification system - Google Patents

Description

  The present invention relates to an exhaust gas purification system in which a waiting time from a regeneration request to a regeneration start is shortened when a PTO device (power take-off device) is operated in regeneration of a DPF (diesel particulate filter) in an idling operation for a long time.

  Particulate matter (particulate matter: hereinafter referred to as PM) discharged from a diesel engine is continuously regenerated into one of the exhaust gas purification devices that collects it with a filter called diesel particulate filter (hereinafter referred to as DPF). There is a type DPF device.

  In this continuous regeneration type DPF device, when the exhaust gas temperature is about 350 ° C. or higher, PM trapped in the DPF is continuously burned and purified, and the DPF self-regenerates. Is low, the temperature of the catalyst is lowered and the catalyst is not activated, so that it is difficult to oxidize PM and self-regenerate DPF. For this reason, clogging progresses due to accumulation of PM on the DPF, which causes a problem of increased exhaust pressure due to this clogging.

  Therefore, when the amount of PM deposited on the DPF exceeds a predetermined amount (threshold), exhaust gas is forced by multistage delayed injection (multi-injection), post-injection (post-injection), etc. in the cylinder (in-cylinder). The forced regeneration for forcibly burning and removing the collected PM is performed. In this forced regeneration, HC (hydrocarbon) supplied into the exhaust gas by post injection or the like is burned by an oxidation catalyst disposed on the upstream side of the DPF or an oxidation catalyst supported on the DPF, thereby generating this oxidation reaction heat. The exhaust gas temperature at the inlet of the DPF and the filter surface of the DPF is raised using the above, the DPF is heated to a temperature higher than the temperature at which the PM accumulated in the DPF burns, and the PM is burned and removed.

  The forced regeneration includes a manual regeneration and an automatic regeneration. In the case of manual regeneration, when the clogging of the DPF exceeds a predetermined amount, a warning is given to the driver, and the driver who has received this warning presses the button for starting forced regeneration, Perform forced regeneration. On the other hand, in automatic regeneration, when filter clogging exceeds a predetermined amount, forced regeneration is performed even when the vehicle is traveling automatically without giving a warning to the driver.

  One of the forced regenerations is forced regeneration during long idling (called Long Low Idle Regeneration: LLIR) that is performed when the idle state is continued for a predetermined time or longer. In specially equipped vehicles equipped with a PTO device, the PTO device If forced regeneration is performed during operation, delayed injection is susceptible to rotational fluctuations because combustion is unstable, and the engine speed changes because transient combustion is unstable because the injection timing is greatly changed by the load. There is a problem that the influence will occur.

  In order to solve this problem, in the prior art, the forced regeneration of the DPF is prohibited in the idle state and when the PTO device is operated. For example, in a specially equipped vehicle that can take out engine power in an idling state via a PTO device and drive an accessory, and in an exhaust purification device that performs forced regeneration control that increases the engine speed in forced regeneration in the idling state In order to avoid sudden changes in the operating state of the engine and malfunctioning of the auxiliary equipment that occur when forced regeneration is performed under conditions where the PTO device is in operation, forced regeneration such as addition of post-injection or increase in rotational speed is necessary under this condition. An exhaust emission control device has been proposed in which a regeneration control command for performing the control is not output (see, for example, Patent Document 1). Also, with the same exhaust gas purifying device, focusing on the substantial operation of the PTO device, only when the PTO device is switched on and an operation input to the auxiliary device by a special lever of the external accelerator is detected. An exhaust gas purification device configured so that a temperature increase control command is not output from the control device has also been proposed (see, for example, Patent Document 2).

  On the other hand, the specially equipped vehicle loads a large amount of PM in the DPF in a shorter time than the standard vehicle that does not have special equipment due to the load of special equipment. If prohibited during operation, clogging of the DPF occurs, and the exhaust pressure rises excessively, causing problems in engine operation. In other words, when low-medium load operation is repeated, such as when the PTO device is operating for long periods of idle operation, the DPF cannot be forcibly regenerated even though PM accumulates in a short time. PM accumulates excessively in the DPF. In order to forcibly regenerate the DPF in order to eliminate this PM accumulation, it is necessary to interrupt the PTO operation, which causes a problem of reducing the work efficiency.

  In order to solve this problem, in a specially equipped vehicle equipped with a DPF for purifying PM in exhaust gas, even if the engine is in an idling state for a long time and the PTO is in operation, the multi-injection control is prohibited. An exhaust gas purification system has also been proposed in which forced regeneration is performed while avoiding rotational fluctuations so that the DPF can be maintained in a good state (see Patent Document 3).

JP 2004-150417 A JP 2005-139944 A JP 2008-180154 A

  By the way, in the control of LLIR, since the vehicle is stopped and it is difficult to calculate the PM accumulation amount based on the travel distance or the differential pressure of the DPF, the PM accumulation amount is calculated based on the stop time. For this reason, there is a possibility that a regeneration request will be issued and forced regeneration will start even when the vehicle is temporarily stopped due to a signal waiting, etc. This forced regeneration is performed automatically corresponding to manual regeneration, and the vehicle is stopped. It is forced to play in the state, and convenience is bad. Therefore, in order to solve such a problem, it is conceivable to set a predetermined waiting time longer than the waiting time of the traffic signal, for example, between the reproduction request and the reproduction start.

  However, some specially equipped vehicles have a short work time for one time. In this case as well, if the waiting time is applied, the work time of the short PTO device can be effectively used for the regeneration of the DPF. difficult.

  The present invention has been made to solve the above-described problems, and its purpose is to reduce the working time of a short PTO device in a specially equipped vehicle equipped with a DPF for purifying PM in exhaust gas. It is an object of the present invention to provide an exhaust gas purification system that can be effectively used for the regeneration of the gas.

In order to achieve the above object, the present invention includes a control device that includes an exhaust gas purification device having a diesel particulate filter in an exhaust passage of an internal combustion engine mounted on a vehicle, and that performs forced regeneration of the diesel particulate filter. In the exhaust gas purification system provided,
The control device provides a predetermined waiting time from the forced regeneration regeneration request to the regeneration start based on the PM accumulation amount calculated based on the stop time from the stop of the vehicle, and the wait time is a power take-off. The first waiting time is when the device is switched off, and the second waiting time is shorter than the first waiting time when the power take-off device is switched on. .

  Preferably, the control device performs the forced regeneration when the switch of the power take-off device is on and the internal combustion engine is in a high load and high exhaust temperature state.

  According to the present invention, in a specially equipped vehicle equipped with a DPF for purifying PM in exhaust gas, a short working time of the PTO device can be effectively used for regeneration of the DPF.

1 is a diagram illustrating an overall configuration of an exhaust gas purification system according to an embodiment of the present invention. It is a figure explaining the waiting time of reproduction at the time of non-use of PTO. It is a figure explaining the waiting time of reproduction at the time of PTO use.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is explained in full detail based on an accompanying drawing.

  FIG. 1 shows a configuration of an exhaust gas purification system 1 according to this embodiment. The exhaust gas purification system 1 includes an exhaust gas purification device 12 and a silencer 13 in an exhaust passage 11 of a diesel engine (internal combustion engine) 10. This exhaust gas purification device 12 is one of continuous regeneration type DPF (diesel particulate filter or DPD: also called diesel particulate diffuser) devices, an oxidation catalyst device 12a on the upstream side and a filter with a catalyst on the downstream side. A device (DPF) 12b is arranged. The DPF 12b is made of CSF (Catalyzed Soot Filter). The exhaust gas G is purified by the exhaust gas purification device 12 and released into the atmosphere via the silencer 13 as purified exhaust gas Gc.

  The oxidation catalyst device 12a is formed by supporting an oxidation catalyst such as platinum on a carrier such as a porous ceramic honeycomb structure. The filter device 12b with catalyst is formed of a monolith honeycomb wall flow type filter or the like in which the inlet and outlet of a porous ceramic honeycomb channel are alternately plugged. A catalyst such as platinum or cerium oxide is supported on the filter. PM (particulate matter) in the exhaust gas G is collected (trapped) by a porous ceramic wall.

  In order to estimate the amount of PM accumulated in the filter device with catalyst 12b, a differential pressure sensor 31 is provided in a conducting pipe connected before and after the exhaust gas purification device 12. An exhaust throttle valve 14 is provided as an exhaust throttle means on the downstream side or upstream side of the exhaust gas purification device 12.

  The intake passage 15 is provided with an air cleaner 16, a MAF sensor (intake air amount sensor) 17, and an intake throttle valve (intake throttle) 18. The intake throttle valve 18 adjusts the amount of intake air A that enters the intake manifold. The EGR passage 19 is provided with an EGR cooler 39 and an EGR valve 21 that adjusts the EGR amount. The exhaust passage 11 is provided with a turbine portion 36 a of a turbocharger 36, and the intake passage 15 is provided with a compressor portion 36 b of a darbocharger 36.

  Further, an oxidation catalyst inlet exhaust temperature sensor 32 is provided upstream of the oxidation catalyst device 12a for forced regeneration control of the filter device with catalyst 12b, and the filter inlet exhaust temperature is between the oxidation catalyst device 12a and the filter device with catalyst 12b. A sensor 33 is provided. The oxidation catalyst inlet exhaust temperature sensor 32 detects an oxidation catalyst inlet exhaust temperature Tg1, which is the temperature of the exhaust gas G flowing into the oxidation catalyst device 12a. The filter inlet exhaust temperature sensor 33 detects a filter inlet exhaust temperature Tg2, which is the temperature of the exhaust gas G flowing into the filter device 12b with catalyst.

  The output values of these sensors are input to a control device (ECU: engine control unit) 40 that performs overall control of the operation of the engine 10 and also performs forced regeneration control of the exhaust gas purification device 12. The exhaust throttle valve 14, the intake throttle valve 18, the EGR valve 21, the fuel injection device (injection nozzle) 22, etc. are controlled by the control signal output from.

  The fuel injection device 22 is connected to a common rail injection system (not shown) that temporarily stores high-pressure fuel boosted by a fuel pump (not shown). In addition to the information such as the accelerator opening from the accelerator position sensor (APS) 34 and the engine speed from the rotation speed sensor 35, information such as the vehicle speed and the coolant temperature is also input. An energization time signal is output so that the fuel is injected.

  Further, in the forced regeneration control of the exhaust gas purification device 12, not only the forced regeneration is automatically performed during traveling, but also the amount of PM collected by the filter device 12b with catalyst exceeds a certain amount, and the filter device 12b with catalyst. When the vehicle is clogged, the driver (driver) is alerted, and the driver is alerted by flashing to indicate that the driver is stopping and the vehicle can be forcibly replayed. A regeneration indicator lamp 23, an automatic regeneration indicator lamp 24 for displaying that automatic regeneration is being performed, and a manual regeneration button (manual regeneration switch) 25 are provided. In addition, a PTO device (power take-off device) 26 for taking out the power of the engine 10 is provided, and a switch (referred to as a PTO switch) 27 for turning on and off the PTO device 26 is disposed, and a signal of the PTO switch 27 is sent to the control device 40. The PTO device 26 is operated by the control device 40 while being input.

  In the control of the exhaust gas purification system 1, PM is collected in a normal operation. In this normal operation, it is monitored whether or not it is the time for forced regeneration start, and it is the time for forced regeneration start. If judged, forced regeneration is performed. This forced regeneration includes automatic regeneration that performs forced regeneration during traveling, and manual regeneration that is started when the driver presses the manual regeneration button 25 after stopping the vehicle by a warning. The pressure is appropriately selected depending on the pressure value (see Table 1).

  Oil dilution (oil dilution) in which unburned fuel is mixed with engine oil (lubricating oil) by manual injection during post-injection during forced regeneration during traveling in the case of automatic regeneration during traveling ), And automatic regeneration when there is no oil dilution problem eliminates the hassle of inputting a regeneration control start signal (stopping the vehicle and pressing the regeneration button, etc.) It can be reduced and the convenience can be improved.

  In the forced regeneration, the filter inlet exhaust temperature or the oxidation catalyst inlet exhaust temperature, which is the temperature of the exhaust gas detected by the filter inlet exhaust temperature sensor 33 or the oxidation catalyst inlet exhaust temperature sensor 32, is a predetermined first determination temperature (about 250 ° C.). ) When the temperature is lower, multi-injection control is performed to perform exhaust temperature rise control for increasing the exhaust temperature, which is the temperature of the exhaust gas when exhausted from the engine 10, and this filter inlet exhaust temperature Tg2 or oxidation catalyst inlet When the exhaust gas temperature Tg1 becomes equal to or higher than a predetermined first determination temperature (about 250 ° C.), PM combustion removal control for performing post injection is performed to forcibly regenerate the filter with catalyst 12b. In this forced regeneration, when the vehicle is stopped, the exhaust throttle valve 14 is closed to perform exhaust throttling. Note that a regeneration control device that performs these forced regenerations is incorporated in the control device 40. In PM combustion removal control, multi-injection and post-injection are combined as necessary.

  The predetermined first determination temperature is a temperature at which the oxidation catalyst of the oxidation catalyst device 12a is activated when the temperature is equal to or higher than this temperature, and is set to about 250 ° C., for example. Further, the PM trapped in the filter device with catalyst 12b is burned and removed when the temperature of the exhaust gas flowing into the filter device with catalyst 12b becomes equal to or higher than a predetermined second determination temperature (for example, 350 ° C.). . The catalyst-equipped filter device 12b is regenerated by this PM combustion removal.

  In the present embodiment, in particular, the control device 40 has a predetermined interval between the forced regeneration regeneration request and the regeneration start based on the PM emission amount (PM accumulation amount) calculated from the stop time from when the vehicle stopped. This waiting time is longer than the waiting time tc of the traffic signal when the switch (PTO switch) 27 of the PTO device 26 is off (that is, in a normal driving state). A long first waiting time ta (for example, 5 minutes) is set (see Table 1 and FIG. 2). When the PTO switch 27 is on, a second waiting time tb that is shorter than the first waiting time ta. (For example, 1 minute) (see Table 1 and FIG. 3).

  The reason for providing the first waiting time ta is to improve the convenience by avoiding the start of forced regeneration while the vehicle is stopped waiting for a signal. In addition, the second waiting time tb is provided because when a long waiting time is applied even to a short working time such as a concrete pump car, a short working time of the PTO device 26 is reduced. This is because it becomes difficult to effectively use for the regeneration, so that the short working time of the PTO device 26 is effectively utilized for the regeneration of the DPF.

  The controller 40 executes the forced regeneration when the PTO switch 27 is on and the diesel engine 10 is in a high load and high exhaust temperature state. Therefore, in this case, even if the PTO switch 27 is on and the diesel engine 10 is not in a high load or high exhaust temperature state, the forced regeneration is not performed even if regeneration is started after the second waiting time tb. Whether or not the diesel engine 10 has a high load is determined by whether or not the fuel injection amount is a predetermined value or more. Whether the exhaust gas temperature is high or not is determined whether the exhaust gas temperature detected by the filter inlet exhaust temperature sensor 33 or the oxidation catalyst inlet exhaust temperature sensor 32 is equal to or higher than a predetermined determination temperature (about 250 ° C.). It is determined by

  When the PTO device 26 is in an operating state during long-time idle operation in which the duration of the idle operation state of the engine 10 has exceeded a predetermined determination time tic, the exhaust gas temperature Tg2 (or Tg1) is predetermined. Even if the temperature is lower than the first determination temperature Tc1, the multi-injection control for increasing the exhaust temperature is prohibited in order to prevent the engine 10 from rotating. However, even when the multi-injection control is prohibited, when the exhaust gas temperature Tg2 (or Tg1) becomes equal to or higher than the predetermined first determination temperature Tc1, that is, the oxidation catalyst exceeds the activation temperature. At this time, PM combustion removal control for performing post-injection control is performed, the temperature of the exhaust gas flowing into the filter device 12b with catalyst is raised, and the filter 12b with catalyst is forcibly regenerated.

  That is, even when the PTO device 26 is in an operating state during long-time idle regeneration, control is performed so as to perform forced regeneration of the catalyst-equipped filter 12b, and the exhaust gas temperature is high. In this case, the forced regeneration of the filter device with catalyst 12b can be regenerated, but in this control, the multi-injection control performed when the temperature of the exhaust gas is low is prohibited in order to prevent fluctuations in the engine speed.

  Note that when the exhaust gas temperature is lower than the predetermined first determination temperature when the PTO device 26 is not in an operating state even during a long idle operation or when the PTO device 26 is not in an operating state, the multi- Exhaust temperature rise control by injection is performed. Further, when the temperature of the exhaust gas becomes equal to or higher than the predetermined first determination temperature Tc1, PM combustion removal control for performing post injection control is performed to increase the temperature of the exhaust gas flowing into the filter device 12b with catalyst, The filter device 12b with catalyst is forcibly regenerated.

  Next, the operation of the exhaust gas purification system will be described. According to the exhaust gas purification system 1, the exhaust gas purification device 12 having the diesel particulate filter is provided in the exhaust passage of the diesel engine 10 mounted on the vehicle, and the control device 40 performs the forced regeneration of the diesel particulate filter. In the exhaust gas purification system 1 having the above, the control device 40 waits for a predetermined waiting time from the regeneration request for forced regeneration based on the PM accumulation amount calculated from the stop time from the stop of the vehicle to the start of regeneration. The waiting time is a first waiting time ta that is longer than the waiting time tc of the traffic signal when the PTO switch 27 of the PTO device 26 is off, and when the PTO switch 27 is on. Since the second waiting time tb is shorter than the first waiting time ta, the PM in the exhaust gas is reduced. In specially equipped both with a DPF for reduction, the working time of the short time of the PTO device 26 can be effectively utilized for regeneration of the DPF, it can be maintained DPF in a good state.

  Further, in a specially equipped vehicle equipped with a catalyst-equipped filter device 12b for purifying PM in exhaust gas, in forced regeneration control during PTO operation during idling for a long time, multi-injection that causes engine rotation fluctuation is prohibited. Thus, regeneration by post-injection is performed, so that engine rotation fluctuation during PTO operation can be avoided.

  Further, the control device 40 monitors the load condition of the engine 10, and performs the forced regeneration when the PTO switch 27 is on and the engine 10 is in a high load and high exhaust temperature state. The problem that PM is excessively accumulated in the attached filter device 12b is solved, and a problem due to an increase in exhaust pressure does not occur in the engine operation state. That is, the forcible regeneration of the catalyst-attached filter device 12b can be performed without stopping the PTO operation, so that the filter-attached filter device 12b can be prevented from clogging.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the gist of the present invention. . As an exhaust gas purification device of the exhaust gas purification system, the combination of the upstream oxidation catalyst device 12a and the downstream filter device 12b with catalyst has been described as an example, but a filter carrying an oxidation catalyst may be used. . In addition, the post-injection has been described as a method for supplying unburned fuel (HC) to the upstream side of the oxidation catalyst device 12a. However, an unburned fuel supply device is arranged in the exhaust passage 11 and directly from the unburned fuel supply device. An exhaust pipe direct injection method in which unburned fuel is injected into the exhaust passage 11 may be employed.

1 Exhaust gas purification system 10 Diesel engine (internal combustion engine)
11 Exhaust passage 12 Exhaust gas purification device 12a Oxidation catalyst device 12b Filter device with catalyst 26 PTO device (power take-off device)
27 PTO switch 40 Control unit (ECU)
ta first waiting time tb second waiting time

Claims (2)

In an exhaust gas purification system including an exhaust gas purification device having a diesel particulate filter in an exhaust passage of an internal combustion engine mounted on a vehicle, and a control device that performs forced regeneration of the diesel particulate filter,
The control device provides a predetermined waiting time from the forced regeneration regeneration request to the regeneration start based on the PM accumulation amount calculated based on the stop time from the stop of the vehicle, and the wait time is a power take-off. The first waiting time is when the device is switched off, and the second waiting time is shorter than the first waiting time when the power take-off device is switched on. Exhaust gas purification system.   The exhaust gas according to claim 1, wherein the control device performs the forced regeneration when the switch of the power take-off device is on and the internal combustion engine is in a high load and high exhaust temperature state. Purification system.

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