JP4377574B2 - Exhaust purification equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust emission control device.
[0002]
[Prior art]
Particulate matter (particulate matter) discharged from a diesel engine is mainly composed of soot composed of carbonaceous matter and SOF content (Soluble Organic Fraction) composed of high-boiling hydrocarbon components. The composition contains a small amount of sulfate (mist-like sulfuric acid component). As a measure to reduce this type of particulates, a particulate filter is installed in the middle of the exhaust pipe through which the exhaust gas flows. It has been done conventionally.
[0003]
This type of particulate filter has a porous honeycomb structure made of ceramics such as cordierite, and the inlets of the respective flow paths partitioned in a lattice shape are alternately sealed, and the inlets are not sealed. About the flow path, the exit is sealed, and only the exhaust gas which permeate | transmitted the porous thin wall which divides each flow path is discharged | emitted downstream.
[0004]
Then, the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, so that the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. It is necessary to regenerate, but in normal diesel engine operating conditions, there are few opportunities to obtain exhaust temperatures that are high enough for the particulates to self-combust. For example, an appropriate amount for alumina loaded with platinum A catalyst regeneration type particulate filter in which an oxidation catalyst formed by adding rare earth elements such as cerium is integrally supported is being put to practical use.
[0005]
That is, if such a catalyst regeneration type particulate filter is employed, the oxidation reaction of the collected particulates is promoted to lower the ignition temperature, and the particulates can be burned and removed even at an exhaust temperature lower than the conventional one. It becomes possible.
[0006]
However, even when such a catalyst regeneration type particulate filter is adopted, in the operation region where the exhaust gas temperature is low, the trapping amount will exceed the processing amount of particulates. If the exhaust filter continues to operate at a low exhaust temperature, there is still a possibility that the particulate filter will not regenerate well and clogging may still occur. It has been studied to forcibly regenerate the particulate filter by adding fuel to the exhaust gas upstream of the filter.
[0007]
In other words, if fuel is added upstream from the particulate filter, the added fuel undergoes an oxidation reaction on the oxidation catalyst of the particulate filter, and the heat of the reaction raises the catalyst bed temperature to burn out the particulate. Thus, regeneration of the particulate filter is achieved (for example, see Patent Document 1 and Patent Document 2).
[0008]
[Patent Document 1]
JP-A-8-42326 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-30919
[Problems to be solved by the invention]
However, when carrying out the regeneration control as described above, for example, when the vehicle is a long-distance transportation truck, the driver rests in the idling state while being air-conditioned in the service area of the highway, or in the idling state. However, if fuel addition by the fuel addition means is automatically executed in such a situation where the driver cannot confirm the safety of the surrounding area, the high-temperature exhaust gas is generated. There is a risk of being discharged outside the vehicle and hitting a pedestrian or the like passing around the exhaust port.
[0010]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust emission control device with improved safety for high-temperature exhaust gas generated by regeneration control of a particulate filter.
[0011]
[Means for Solving the Problems]
The present invention employs a fuel injection device that is equipped with a catalyst regeneration type particulate filter in the middle of an exhaust pipe through which exhaust gas from an internal combustion engine flows, and that injects fuel into each cylinder of the internal combustion engine as fuel addition means. When the collected particulates need to be burned and removed and the particulate filter needs to be regenerated, the fuel injection control of the fuel injection device is switched from the normal mode to the regenerative mode and is performed near the compression top dead center. In an exhaust emission control device having a control device that performs post-injection at a non-ignition timing later than the compression top dead center following main injection of the engine, idling determination means for determining that the vehicle is in an idling state is provided, and the idling Under conditions where the determination means has confirmed that the idling state continues for a predetermined time or longer, the fuel injection control is set to the normal mode. From de and characterized by being configured the controller to continue as reproduction control if already in the playback mode at the stage before continuing idling over and a predetermined time without switching to the reproduction mode is confirmed To do.
[0012]
Thus, when the idling determination means confirms that the idling state continues for a predetermined time or longer, the fuel injection control of the fuel injection device does not switch from the normal mode to the regeneration mode. The fuel injection control switches from normal mode to regeneration mode when the driver cannot confirm the safety of the surroundings, such as when the vehicle is resting in a state of being idle or away from the vehicle while idling. Will not be discharged to the outside of the vehicle, and the possibility of high-temperature exhaust gas hitting a pedestrian or the like passing around the exhaust port is avoided.
[0013]
In the present invention, the idling determination means includes a rotation sensor for detecting the engine speed, a load sensor for detecting the engine load, a neutral switch for detecting that the gear position is in the neutral position, and a side brake. It can be configured by a combination with any one or more of a side brake switch for detecting the vehicle speed and a vehicle speed sensor for detecting the vehicle speed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
FIG. 1 and FIG. 2 show an example of an embodiment for carrying out the present invention. In FIG. 1, reference numeral 1 denotes a diesel engine equipped with a turbocharger 2, and intake air 4 guided from an air cleaner 3 is an intake pipe 5. And the intake air 4 pressurized by the compressor 2a is sent to the intercooler 6 to be cooled, and the intake air 4 further flows from the intercooler 6 to the intake manifold 7. It is guided and distributed to each cylinder 8 of the diesel engine 1 (the case of in-line 6 cylinders is illustrated in FIG. 1).
[0017]
Further, the exhaust gas 9 discharged from each cylinder 8 of the diesel engine 1 is sent to the turbine 2b of the turbocharger 2 through the exhaust manifold 10, and the exhaust gas 9 that has driven the turbine 2b passes through the exhaust pipe 11. It is designed to be discharged outside the vehicle.
[0018]
Further, in the middle of the exhaust pipe 11, a catalyst regeneration type particulate filter 12 integrally carrying an oxidation catalyst is mounted and mounted on a filter case 13, and is shown in an enlarged view in FIG. As described above, the particulate filter 12 has a porous honeycomb structure made of ceramic, and the inlets of the respective channels 12a partitioned in a lattice pattern are alternately sealed, and the channels are not sealed. About 12a, the exit is sealed, and only the exhaust gas 9 which permeate | transmitted the porous thin wall 12b which divides each flow path 12a is discharged | emitted downstream.
[0019]
A temperature sensor 14 that measures the temperature of the exhaust gas 9 that has passed through the particulate filter 12 as a substitute value for the catalyst bed temperature is provided at the outlet of the filter case 13, and a temperature signal 14 a of the temperature sensor 14 is provided. Is input to a control device 15 constituting an engine control computer (ECU: Electronic Control Unit).
[0020]
Since this control device 15 also serves as an engine control computer, it is also responsible for control related to fuel injection. More specifically, the control device 15 detects an accelerator opening as a load of the diesel engine 1 ( A fuel injection device that injects fuel into each cylinder 8 of the diesel engine 1 based on an accelerator opening signal 16a from the load sensor) and a rotation speed signal 17a from the rotation sensor 17 that detects the engine rotation speed of the diesel engine 1. The fuel injection signal 18a is output toward the engine 18, and the operation state of the diesel engine 1 is always grasped by the control device 15 when the fuel injection signal 18a is output.
[0021]
Here, the fuel injection device 18 is composed of a plurality of injectors 19 provided for each cylinder 8, and the electromagnetic valves of these injectors 19 are appropriately controlled to open by the fuel injection signal 18a. The injection timing (valve opening timing) and the injection amount (valve opening time) are appropriately controlled.
[0022]
On the other hand, in the control device 15, the fuel injection signal 18a in the normal mode is determined on the basis of the accelerator opening signal 16a and the rotation speed signal 17a. On the other hand, it is necessary to perform regeneration control of the particulate filter 12. In this case, the normal mode is switched to the regeneration mode, and the post-injection is performed at the non-ignition timing later than the compression top dead center following the main injection of fuel performed near the compression top dead center (crank angle 0 °). The fuel injection signal 18a of the injection pattern is determined.
[0023]
That is, when post-injection is performed at a non-ignition timing later than the compression top dead center following main injection, unburned fuel (mainly HC: hydrocarbon) is added to the exhaust gas 9 by this post-injection. As a result, the unburned fuel undergoes an oxidation reaction on the oxidation catalyst on the surface of the particulate filter 12, the catalyst bed temperature rises due to the reaction heat, and the particulates in the particulate filter 12 are burned and removed. It will be.
[0024]
Further, the control device 15 extracts the rotational speed of the diesel engine 1 based on the rotational speed signal 17a from the rotational sensor 17, and at the time of determining the fuel injection signal 18a based on the accelerator opening signal 16a from the accelerator sensor 16. The known fuel injection amount is extracted, and the basic generation amount of the particulates based on the current operation state of the diesel engine 1 is estimated from the particulate generation map based on the rotation speed and the injection amount. Multiply the basic generation amount by a correction coefficient considering various conditions related to the generation of particulates, and subtract the particulate processing amount in the current operating state to obtain the final generation amount. The amount of particulates accumulated is estimated from time to time to estimate the amount of particulates deposited.
[0025]
Note that there are various ways of estimating the amount of particulate deposition, and it is of course possible to estimate the amount of particulate deposition using a method other than the estimation method exemplified here.
[0026]
Further, after the control device 15 estimates that the amount of accumulated particulates has reached a predetermined target value, the outlet exhaust temperature of the particulate filter 12 is equal to or higher than the predetermined temperature based on the temperature signal 14a from the temperature sensor 14. After waiting for the condition, the combustion injection control is switched from the normal mode to the regeneration mode, and fuel is added to the exhaust gas 9 on the upstream side of the particulate filter 12.
[0027]
In the present embodiment, the accelerator sensor 16 and the rotation sensor 17 described above relate to the exhaust gas purification apparatus in which fuel can be added to the exhaust gas 9 upstream of the particulate filter 12 as described above. In addition to the above, detection signals 20a and 21a from a neutral switch 20 for detecting that the gear position is in the neutral position, a side brake switch 21 for detecting that the side brake is applied, and a vehicle speed sensor 22 for detecting the vehicle speed, respectively. The vehicle speed signal 22a is also input to the control device 15. Based on these signals, the control device 15 determines whether or not the vehicle is in an idling state.
[0028]
That is, in the control device 15, it is confirmed by the rotation sensor 17 that the rotation speed is within a relatively low predetermined rotation speed range, the accelerator sensor 16 confirms that the accelerator is off (load is zero), and the neutral switch 20 sets the gear position. When it is confirmed that the vehicle is in the neutral position, it is confirmed that the side brake is being pulled by the side brake switch 21, and the vehicle speed is confirmed to be zero by the vehicle speed sensor 22, the current driving state is in the idling state. And the duration of the idling state is counted.
[0029]
Note that not all signals from these sensors and switches are necessarily required to determine the idling state, and at least the rotation sensor 17, the accelerator sensor 16, the neutral switch 20, the side brake switch 21, and the vehicle speed sensor. The idling determination means can be configured by a combination with any one of 22.
[0030]
In the control device 15, the interlock is applied so that a new fuel addition command is not output under the condition that the idling state continues for a predetermined time or more, and more specifically, The combustion injection control is not switched from the normal mode to the regeneration mode under the condition that the idling state continues for a predetermined time or longer.
[0031]
However, if the vehicle is already in the regeneration mode before the idling state for a predetermined time or more is confirmed, the particulate filter 12 continues the regeneration mode as it is even if the vehicle is in the idling state for the predetermined time or more. The playback control is completed.
[0032]
Thus, if the exhaust gas purification apparatus is configured in this way, the particulate matter accumulation amount has reached a predetermined target value in the control device 15 under the condition that the idling state has not been confirmed for a predetermined time or longer. If it is estimated, the combustion injection control is switched from the normal mode to the regeneration mode after waiting for the outlet exhaust temperature of the particulate filter 12 to be equal to or higher than a predetermined temperature based on the temperature signal 14a from the temperature sensor 14. The fuel added unburned in the exhaust gas 9 by post-injection following injection causes an oxidation reaction on the oxidation catalyst of the particulate filter 12 to generate reaction heat, and this reaction heat greatly increases the catalyst bed temperature. Thus, the particulates are burned and removed satisfactorily, and the particulate filter 12 is regenerated.
[0033]
On the other hand, when the idling determination means including the rotation sensor 17, the accelerator sensor 16, the neutral switch 20, the side brake switch 21, and the vehicle speed sensor 22 confirms that the idling state continues for a predetermined time or more, the control device 15 sends the fuel injection device 18 to the fuel injection device 18. Since the output of the new fuel addition command for the vehicle is blocked and the combustion injection control does not switch from the normal mode to the regeneration mode, the driver is resting in the idling state or is away from the vehicle in the idling state In such a situation that the driver cannot confirm the safety of the surroundings, the fuel addition by the post-injection of the fuel injection device 18 is executed, and the situation where the high-temperature exhaust gas 9 is discharged outside the vehicle does not occur. The possibility of high-temperature exhaust gas hitting pedestrians passing through To become.
[0034]
Therefore, according to the above embodiment, the fuel is added to the exhaust gas 9 on the upstream side of the particulate filter 12, the fuel is oxidized on the oxidation catalyst of the particulate filter 12, and the heat of reaction causes the catalyst bed temperature. When the regeneration control for actively burning and removing the collected particulates is performed, the safety of the high-temperature exhaust gas 9 generated by the regeneration control can be greatly improved.
[0035]
The exhaust gas purifying apparatus of the present invention is not limited to the above embodiments, in the previous embodiment, when the determination of the idle should state, such as a clutch signal for the purpose of performing a more reliable determination Of course, other signals may be taken into account, and various changes may be made without departing from the scope of the present invention.
[0036]
【The invention's effect】
According to the above-described exhaust gas purification apparatus of the present invention, fuel is added to the exhaust gas upstream of the particulate filter, the fuel is oxidized on the oxidation catalyst of the particulate filter, and the heat of reaction causes the catalyst bed temperature. In order to carry out regeneration control that actively burns and removes the collected particulates and avoids a situation where regeneration control is newly started when the vehicle is idling for a predetermined time or longer. Therefore, regeneration control is newly started when the driver cannot confirm the safety of the surrounding area, such as when the driver is resting in an idling state or when he is away from the vehicle while idling. The particulate filter can avoid the situation where hot exhaust gas hits pedestrians around the exhaust port. An excellent effect can be greatly improved the safety of the high-temperature exhaust gas generated in the regeneration control.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an embodiment for carrying out the present invention.
FIG. 2 is a cross-sectional view showing details of the particulate filter of FIG.
[Explanation of symbols]
1 Diesel engine (internal combustion engine)
8 Cylinder 9 Exhaust gas 11 Exhaust pipe 12 Particulate filter 15 Control device 16 Accelerator sensor (idling determination means)
17 Rotation sensor (idling determination means)
18 Fuel injector (fuel addition means)
20 Neutral switch (idling determination means)
21 Side brake switch (idling determination means)
22 Vehicle speed sensor (idling determination means)

Claims (2)

Equipped with a catalyst regeneration type particulate filter in the middle of the exhaust pipe through which exhaust gas from the internal combustion engine flows, and a fuel injection device that injects fuel into each cylinder of the internal combustion engine as fuel addition means When it becomes necessary to regenerate the particulate filter by burning and removing the particulates, the fuel injection control of the fuel injection device is switched from the normal mode to the regeneration mode, and the main injection of fuel performed near the compression top dead center Subsequently, in an exhaust emission control device including a control device that performs post-injection at a timing of non-ignition later than the compression top dead center, an idling determination unit that determines whether the vehicle is in an idling state is provided, and the idling determination unit determines a predetermined value. Under conditions where it is confirmed that the idling state continues for more than an hour, the fuel injection control is resumed from the normal mode. Exhaust gas purification, characterized in that already constitute the controller to continue as reproduction control if entered the playback mode at the stage before and continuing idling of more than a predetermined time without switching to the mode is confirmed apparatus.   A rotation sensor that detects the engine speed, a load sensor that detects the engine load, a neutral switch that detects that the gear is in the neutral position, a side brake switch that detects that the side brake is being pulled, and a vehicle speed The exhaust emission control device according to claim 1, wherein the idling determination means is configured by a combination with any one or more of the vehicle speed sensors for detecting the engine.

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