JP2004150417A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the generation of operation failure in an engine accessory due to the regenerative control of a particulate filter during the time when the accessory on a specially equipped vehicle is used. <P>SOLUTION: This exhaust emission control device to be used for a special equipped vehicle wherein the accessory 15 is driven by taking the engine power in the idling condition through a power take-off device 14 is provided with a catalytic regeneration type particulate filter 6 installed on the way of an exhaust pipe 4, and a control device 9 for outputting a regenerative control command to a fuel injection device 10 to add the post injection at a non-ignition timing continuously to the fuel main injection and to increase the injection quantity per each time of the main injection to raise the engine speed in comparison with the normal idling condition when carrying out the post injection in the idling condition. A regenerative control command is not output from the control device 9 under the condition that the power take-off device 14 is operated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purification device.
[0002]
[Prior art]
Particulate matter (particulate matter) discharged from the diesel engine is mainly composed of soot composed of carbonaceous material and SOF component (Soluble Organic Fraction: soluble organic component) composed of a high-boiling hydrocarbon component. Although it has a composition containing a small amount of sulfate (mist-like sulfuric acid component), as a measure to reduce this kind of particulates, it is necessary to equip a particulate filter in the middle of the exhaust pipe through which exhaust gas flows. This has been done conventionally.
[0003]
This kind of particulate filter has a porous honeycomb structure made of ceramic such as cordierite, and the inlets of the respective flow paths partitioned in a lattice are alternately plugged, and the inlets are not plugged. The outlets of the flow passages are sealed so that only the exhaust gas that has passed through the thin porous wall that defines each flow passage is discharged to the downstream side.
[0004]
Since the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging, and the particulate filter is removed. It is necessary to regenerate, but in the normal diesel engine operating state, there is little chance of obtaining a high exhaust temperature enough for the particulates to self-combust, so for example, an appropriate amount of alumina loaded with platinum A catalyst regeneration type particulate filter integrally supporting an oxidation catalyst formed by adding a rare earth element such as cerium has been put into practical use.
[0005]
That is, if such a catalyst regeneration type particulate filter is employed, the oxidation reaction of the collected particulates is promoted, the ignition temperature is lowered, and the particulates can be burned and removed even at a lower exhaust temperature than before. It is possible.
[0006]
However, even when such a catalyst regeneration type particulate filter is employed, in the operating region where the exhaust gas temperature is low, the trapped amount exceeds the treated amount of the particulate, so that such low exhaust gas If the operating condition at the temperature continues, there is a risk that the regeneration of the particulate filter does not proceed satisfactorily and the particulate filter falls into an over-collection state, and at the stage where the accumulation amount of the particulate filter increases, It has been considered to add fuel to the exhaust gas on the more upstream side to perform forced regeneration of the particulate filter.
[0007]
That is, if fuel is added upstream of 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, the regeneration of the particulate filter is achieved.
[0008]
Incidentally, a method of actively regenerating this type of particulate filter is also described in the following unpublished prior applications, Patent Document 1 and Patent Document 2, and in the descriptions in these documents, Fuel addition is performed by performing post-injection at a non-ignition timing later than the compression top dead center with respect to the fuel injection device of the engine following the main injection of the fuel performed near the compression top dead center.
[0009]
[Patent Document 1]
Japanese Patent Application No. 2001-355061 [Patent Document 2]
Japanese Patent Application No. 2002-20374 [0010]
[Problems to be solved by the invention]
However, when performing the regeneration control as described above, for example, when the vehicle is a specially equipped vehicle (special equipment vehicle) such as a crane truck or a fire engine, the engine power is supplemented by a hydraulic pump or the like for purposes other than traveling. If the regeneration control is automatically performed by adding fuel when such auxiliary equipment is used, the operation state of the engine changes suddenly and malfunction of auxiliary equipment such as a hydraulic pump may occur. May be caused.
[0011]
That is, in this type of specially equipped vehicle, the auxiliary machine is used while the vehicle is idling and stopped. However, when the particulate filter regeneration control is performed in the idling state, the temperature and flow rate of the exhaust gas are low. It is difficult to remove and burn particulates properly, and by increasing the injection amount per main injection, the number of revolutions is increased from that during normal idling, thereby increasing the energy input and reducing exhaust gas emissions. Since it is necessary to add control to raise the temperature and flow rate to levels suitable for regeneration control, the post-injection is added after the rotation speed is increased compared to normal idling, and the driver is able to operate the auxiliary equipment. It was feared that unexpected fluctuations would occur.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to avoid malfunction of an auxiliary machine due to execution of particulate filter regeneration control when the auxiliary machine is used in a specially equipped vehicle.
[0013]
[Means for Solving the Problems]
The present invention is an exhaust gas purifying apparatus for applying to a specially-equipped vehicle capable of driving an auxiliary machine by taking out engine power in an idling state via a power take-off device, wherein an exhaust pipe through which exhaust gas from the engine flows is provided. When it is necessary to regenerate the particulate filter by burning and removing the trapped particulates, the catalyst regeneration type particulate filter installed on the way and the engine fuel injection device near the compression top dead center Following the main injection of fuel to be performed, post injection is added at a non-ignition timing later than the compression top dead center, and main injection is performed only when the post injection is performed in the idling state so as to increase the engine speed from the time of normal idling. And a control device for outputting a regeneration control command for increasing the injection amount per injection. Off device is characterized in that the reproduction control command from the control device under a certain condition in operation is configured to not output.
[0014]
According to this configuration, when the power take-off device is in the operating state, the output of the regeneration control command from the control device to the fuel injection device is blocked, so that the engine power is kept in the idling state via the power take-off device. In a situation where the auxiliary equipment is taken out and driven, regeneration control by addition of post-injection or an increase in the number of rotations is not performed, and a situation in which the operating state of the engine is suddenly changed and malfunction of the auxiliary equipment does not occur does not occur.
[0015]
On the other hand, if it becomes necessary to regenerate the particulate filter during normal running, post-injection is executed by the fuel injection device in accordance with a regeneration control command from the control device, and as a result, unburned fuel added to the exhaust gas is released. Is oxidized on the oxidation catalyst of the particulate filter, the heat of the reaction raises the catalyst bed temperature, and the particulates in the particulate filter are forcibly burned off.
[0016]
Further, when it is necessary to regenerate the particulate filter in an idling state in which the power take-off device is inactive, post-injection is executed by the fuel injection device according to a regeneration control command from the control device. In addition, the injection amount per main injection is increased, and the engine speed becomes higher than during normal idling.
[0017]
As a result, the temperature and flow rate of the exhaust gas are raised to levels suitable for regeneration control, and the unburned fuel added to the exhaust gas undergoes an oxidation reaction on the oxidation catalyst of the particulate filter, and the heat of the reaction causes the catalyst to react. The bed temperature rises and the particulates in the particulate filter are forcibly burned off.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIGS. 1 and 2 show an embodiment of the present invention. In this embodiment, a specially equipped vehicle such as a crane vehicle as shown in FIG. 1 is used. A catalyst regeneration type particulate filter 6 integrally supporting an oxidation catalyst is accommodated in a muffler 5 of an exhaust pipe 4 through which exhaust gas 3 discharged through the exhaust gas 3 flows, A filter case 7 that holds the particulate filter 6 forms an outer cylinder of the muffler 5.
[0020]
That is, a particulate filter 6 as shown in an enlarged view in FIG. 2 is housed inside the filter case 7, and the particulate filter 6 has a porous honeycomb structure made of ceramic and has a lattice structure. The inlets of the flow paths 6a partitioned in a shape are alternately plugged, and the outlets of the flow paths 6a whose inlets are not plugged are plugged. Only the exhaust gas 3 that has passed through the porous thin wall 6b is exhausted downstream.
[0021]
A pressure sensor 8 is provided on the inlet side of the filter case 7, and a pressure signal 8a of the pressure sensor 8 is input to a control device 9 which forms an engine control computer (ECU: Electronic Control Unit). In the control device 9, the pressure difference between the inlet side and the outlet side of the particulate filter 6 (the pressure loss on the outlet side is initially set in advance) based on the pressure signal 8a from the pressure sensor 8 is within the normal range. Is determined, and when the pressure difference exceeds the normal range, it is determined that the particulate filter 6 has fallen into an excessive collection state.
[0022]
Further, since this control device 9 also serves as an engine control computer, it also controls fuel injection, and more specifically, an accelerator sensor for detecting the accelerator opening as a load on the diesel engine 1. Fuel injection for injecting fuel into each cylinder of the diesel engine 1 based on an accelerator opening signal 11a from the load sensor 11 and a rotation speed signal 12a from a rotation sensor 12 for detecting the engine rotation speed of the diesel engine 1 A fuel injection signal 10a is output to the device 10.
[0023]
Here, the fuel injection device 10 is constituted by a plurality of injectors provided for each cylinder, and the solenoid valves of these injectors are appropriately controlled to open according to the fuel injection signal 10a, and the fuel injection timing is adjusted. (Valve opening timing) and the injection amount (valve opening time) are appropriately controlled.
[0024]
On the other hand, in the control device 9, while the fuel injection signal 10a in the normal mode is determined based on the accelerator opening signal 11a and the rotation speed signal 12a, it is necessary to perform the regeneration control of the particulate filter 6. In this case, the mode is switched from the normal mode to the regeneration mode, and the post-injection is performed at a non-ignition timing later than the compression top dead center following the fuel main injection performed near the compression top dead center (crank angle 0 °). The fuel injection signal 10a of the injection pattern is determined.
[0025]
That is, when the post injection is performed at the non-ignition timing later than the compression top dead center following the main injection, unburned fuel (mainly HC: hydrocarbon) is added to the exhaust gas 3 by the post injection. The unburned fuel undergoes an oxidation reaction on the oxidation catalyst on the surface of the particulate filter 6, and the heat of the reaction raises the catalyst bed temperature to burn and remove the particulates in the particulate filter 6. Will be.
[0026]
However, when the vehicle is in the idling state when the mode is switched to the regeneration mode, the main injection performed near the compression top dead center (crank angle 0 °) in order to increase the rotation speed from normal idling The injection amount is also increased.
[0027]
That is, when the particulate filter 6 is forcibly regenerated at the time of idling stop, the temperature and the flow rate of the exhaust gas 3 are too low, so that it is difficult to satisfactorily remove and burn the particulates. By increasing the injection amount, the number of revolutions is increased from that during normal idling, whereby the energy input amount is increased, and the temperature and flow rate of the exhaust gas 3 are raised to levels suitable for forced regeneration.
[0028]
Further, in addition to the control for increasing the rotation speed of the diesel engine 1, the after-injection may be performed at a combustible timing immediately after the main injection, if necessary. When the after-injection is performed at a possible timing, the fuel of the after-injection is burned at a timing that is difficult to be converted into an output, thereby lowering the thermal efficiency of the diesel engine 1 and increasing the calorific value of the calorific value of the fuel that is not used for power. Thus, it is possible to further increase the exhaust gas temperature.
[0029]
Although not particularly shown in FIG. 1, in addition to the accelerator sensor 11 and the rotation sensor 12 described above, a neutral switch for detecting that the gear position is in the neutral position, and a side brake are applied. Detection signals from the side brake switch for detecting the vehicle speed and a vehicle speed sensor for detecting the vehicle speed are also input to the control device 9.Based on these detection signals, it is determined whether or not the vehicle is in an idling state. The determination is made by the control device 9.
[0030]
That is, in the control device 9, the rotation sensor 12 confirms that the rotation speed is in a relatively low predetermined rotation speed range, the accelerator sensor 11 confirms that the accelerator is off (the load is zero), and the neutral switch sets the gear position to the neutral position. When the vehicle is in the position, the side brake switch is used to confirm that the side brake is applied, and when the vehicle speed sensor confirms that the vehicle speed is zero, it is determined that the current driving state is the idling state. It has become.
[0031]
Note that the determination of the idling state does not necessarily require all signals from these sensors and switches. At least one of the rotation sensor 12, the accelerator sensor 11, the neutral switch, the side brake switch, and the vehicle speed sensor is required. The idling determination means can be configured by a combination of the above and another signal such as a clutch signal may be considered for the purpose of making a more reliable determination.
[0032]
In a specially equipped vehicle as shown in FIG. 1, a power take-off device 14 is provided on a side surface of the transmission 13 so that power can be taken out from a countershaft gear of the transmission 13 via a gear train. The power taken out of the transmission 13 is output from an output shaft of a power take-off device 14 to an auxiliary device 15 such as a hydraulic pump. This is performed inside the power take-off device 14.
[0033]
However, as for the method of extracting the engine power, various methods such as the transmission PTO method described above and the flywheel PTO method in which the power is extracted from the gear provided on the flywheel at the front of the transmission 13 are employed. It is possible to do.
[0034]
On the other hand, the instrument panel in the cab is provided with a PTO switch 16 for taking out the engine power via the power take-off device 14 and driving the auxiliary machine 15, and the PTO switch 16 is turned on. As a result, the PTO command signal 14a is output from the control device 9 which has received the ON signal 16a to the power take-off device 14, and the output of the power take-off device 14 is turned on, while the external accelerator 17 separately installed outside the cab is provided. Is made effective.
[0035]
That is, the external accelerator 17 is configured to operate the specially equipped accelerator sensor 18 outside the cab with the specially equipped lever 19, and the external accelerator opening signal 18a from the specially equipped accelerator sensor 18 when the PTO switch 16 is turned on. Are electrically enabled in the control device 9 as control signals for the diesel engine 1 so that the rotation speed of the diesel engine 1 can be controlled outside the cab without depressing the accelerator pedal inside the cab.
[0036]
However, the control device 9 outputs the fuel injection signal 10a (regeneration control command) in the regeneration mode under the condition that the ON signal 16a of the PTO switch 16 is received, that is, under the condition that the power take-off device 14 is operating. An interlock is applied so as not to be performed, and more specifically, the combustion injection control is not switched from the normal mode to the regeneration mode.
[0037]
Thus, when the power take-off device 14 is in the operating state, the output of the fuel injection signal 10a in the regeneration mode from the control device 9 to the fuel injection device 10 is blocked. When the auxiliary machine 15 is driven while being taken out in an idling state via the take-off device 14, regeneration control due to addition of post-injection or an increase in the rotation speed is not performed, and the operating state of the diesel engine 1 changes suddenly, and A situation such as the operation failure of No. 15 does not occur.
[0038]
On the other hand, when it becomes necessary to regenerate the particulate filter 6 during normal running, post-injection is executed by the fuel injection device 10 by the fuel injection signal 10a (regeneration control command) in the regeneration mode from the control device 9. As a result, the unburned fuel added to the exhaust gas 3 undergoes an oxidation reaction on the oxidation catalyst of the particulate filter 6, and the reaction heat raises the catalyst bed temperature and the particulates in the particulate filter 6 are forcibly forced. It will be combusted and removed.
[0039]
Further, when it is necessary to regenerate the particulate filter 6 in the idling state in which the power take-off device 14 is in the non-operating state, the fuel injection signal 10a (regeneration control command) in the regeneration mode from the control device 9 causes the regeneration. While the post injection is performed by the fuel injection device 10, the injection amount per main injection is increased, and the rotation speed of the diesel engine 1 becomes higher than during normal idling.
[0040]
As a result, the temperature and flow rate of the exhaust gas 3 are raised to levels suitable for regeneration control, and the unburned fuel added to the exhaust gas 3 undergoes an oxidation reaction on the oxidation catalyst of the particulate filter 6, and the reaction proceeds. The heat raises the catalyst bed temperature, and the particulates in the particulate filter 6 are forcibly burned off.
[0041]
Therefore, according to the above embodiment, the regeneration control by adding post-injection or increasing the rotation speed is not performed under the condition that the engine power is taken out in the idling state via the power take-off device 14 and the auxiliary machine 15 is driven. Therefore, it is possible to reliably avoid a situation in which the operation state of the diesel engine 1 suddenly changes due to the regeneration control and causes malfunction of the auxiliary device 15.
[0042]
It should be noted that the exhaust gas purifying apparatus of the present invention is not limited to the above-described embodiment, but may reduce the exhaust flow rate or increase the intake flow rate in order to further increase the temperature of the exhaust gas during the regeneration control of the particulate filter. It goes without saying that various means can be added within a range not departing from the gist of the present invention.
[0043]
【The invention's effect】
According to the exhaust gas purifying apparatus of the present invention described above, the regeneration control by adding post-injection or increasing the rotation speed is not performed under the condition that the engine power is taken out through the power take-off device in an idling state and the auxiliary machine is driven. Therefore, it is possible to achieve an excellent effect that it is possible to reliably avoid a situation in which the operating state of the engine is suddenly changed by the regeneration control and malfunction of the auxiliary machine is caused.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of an embodiment for carrying out the present invention.
FIG. 2 is a sectional view showing details of the particulate filter of FIG. 1;
[Explanation of symbols]
1 Diesel engine (engine)
3 Exhaust gas 4 Exhaust pipe 6 Particulate filter 9 Control device 10 Fuel injection device 10a Fuel injection signal 14 Power take-off device 14a PTO command signal 15 Auxiliary device 16 PTO switch 16a ON signal

Claims (1)

An exhaust purification device for applying to a specially equipped vehicle that can take out engine power in an idling state via a power take-off device and drive an auxiliary machine, and is provided in the middle of an exhaust pipe through which exhaust gas from the engine flows. A catalyst regeneration type particulate filter and a fuel injection device for a fuel injection device near the compression top dead center when a need arises to regenerate the particulate filter by burning and removing the collected particulates. After the main injection, post injection is added at the timing of non-ignition later than the compression top dead center, and only during the execution of the post injection in the idling state is the main injection per injection to increase the engine rotation speed from normal idling. And a control device for outputting a regeneration control command for increasing the injection amount of the power take-off device. Exhaust purifying apparatus under conditions in the dynamic state from said control device characterized by being configured as playback control command is not output.

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