DE112006000441T5 - Exhaust gas purification device for an internal combustion engine - Google Patents

Abstract

An exhaust purification device for an internal combustion engine, comprising:
an exhaust gas purifying agent provided in an exhaust gas passage of the internal combustion engine to purify exhaust gas discharged from the internal combustion engine;
an auxiliary supply means for providing a means for maintaining the exhaust gas purifying function of the exhaust gas purifying means upstream of the exhaust gas purifying means into the exhaust passage,
a variation factor parameter detection means for detecting the value of a variation factor parameter causing changes in the amount of the supplied resource, and
a control means for controlling the auxiliary supply means and thereby regulating the amount of the auxiliary agent supplied into the exhaust passage,
wherein the control means includes:
a standard supply amount determination section for determining the default delivery amount of the auxiliary resource required for maintaining the exhaust gas purification function of the exhaust gas purification device;
a destination delivery quantity determining section for determining, by a correction of the standard delivery quantity determined by the standard delivery quantity determining section, the target delivery amount of the resource based on the value of the parameter detected by the change factor parameter setting means; and
a delivery tax section to ...

Description

Technical area

The The present invention relates to an exhaust gas purification device for a Internal combustion engine and more particularly an exhaust gas purification device, the a tool used to maintain an exhaust gas purification function.

General state of the art

Around Pollutants contained in the exhaust gas of an internal combustion engine, such as HC (hydrocarbons), CO (carbon monoxide) and NOx (nitrogen oxides), to convert to purify the exhaust gas is conventionally an exhaust gas purifying catalyst used. In the case of a diesel engine, in addition to such Emission control catalyst a particulate filter for capturing particulate matter, which is contained in the exhaust gas used. In some of the exhaust gas purification devices such as exhaust gas purifying catalysts and particulate filters will Aid used to preserve their emission control function.

In Some particulate filters use fuel as an aid upstream of the engine Particulate filter supplied in an exhaust passage to the by To burn off the particulate matter trapped by the particulate filter and thereby to regenerate the particulate filter and the particulate matter catching function to preserve if the particulate matter trapped in the particulate filter and collected, reaches a predetermined amount. There are too Exhaust gas purification catalysts are known in which an aid in a similar Way in the exhaust passage is supplied to the exhaust gas purification function to preserve.

As a catalyst for converting NO x contained in the exhaust gas into harmless substances, for example, there is known a NO x adsorption catalyst which is designed to adsorb NO x contained in the exhaust gas when the air-fuel ratio of the exhaust gas is lean is to release and reduce the adsorbed NOx when the air-fuel ratio of the exhaust gas is rich. Since the capacity of the NOx adsorption catalyst for adsorbing NOx is limited, it is necessary to cause the adsorbed NOx to be released and reduced. Therefore, for example, from the Japanese Unexamined Patent Publication No. 2000-205005 (hereinafter referred to as Patent Document 1) an exhaust gas purifying apparatus is known in which, to maintain the exhaust gas purifying function of the NOx adsorption catalyst by causing the adsorbed NOx to be released and reduced, a fuel addition valve is provided at the exhaust gas passage upstream of the NOx adsorption catalyst to allow the fuel , which is needed to cause the release and reduction of NOx, injected into the exhaust passage and delivered to the NOx adsorption catalyst.

at the exhaust gas purification device shown in Patent Document 1 fuel is in the amount needed to cause the NOx adsorption catalyst releases the adsorbed NOx and reduced by the fuel addition valve upstream of the NOx adsorption catalyst injected into the exhaust passage, such that exhaust gas having a rich air-fuel ratio causes the NOx adsorption catalyst enters and causes the NOx Adsorptionskatalyator the adsorbed NOx releases and reduces. In this process, the amount of delivered Fuel by changing the valve opening time the fuel addition valve, the amount of fuel which is injected into the exhaust pipe, increases when the valve opening time gets longer.

The Amount of fuel needed to cause the NOx adsorption catalyst to cause the adsorbed NOx releases and reduces, or the valve opening time of the additional fuel valve, based on the NOx accumulation amount, namely Amount of NOx adsorbed by the NOx adsorption catalyst was determined, etc. However, it is difficult to control the NOx accumulation amount determine directly. Therefore, actually the valve opening time, the one needed Fuel quantity corresponds, determined from a plan, in advance was created to the valve opening time as a function of the intake air amount and the engine revolution speed specify.

The Amount of fuel flowing from the fuel addition valve into the exhaust passage is injected, however, varies depending on the exhaust pressure in the exhaust passage and the temperature of the delivered fuel. Therefore, it can become the amount of fuel actually from the fuel addition valve in the Exhaust passage is injected, even if the valve opening time, the one needed Fuel quantity corresponding to the intake air quantity and the Engine revolution speed was accurately obtained from the amount of fuel, which was obtained from the plan differ.

In particular, when the delivery pressure of the fuel to be injected is fixed, the pressure difference between the fuel delivery pressure and the exhaust pressure is smaller at a higher exhaust pressure than in the case of a lower exhaust pressure. Therefore, the amount of fuel actually supplied into the exhaust passage during the same valve opening time becomes smaller as the exhaust pressure increases. Especially when an exhaust throttle valve is provided in the exhaust passage to Exhaust brake or to be used for the purpose of controlling the temperature of the exhaust gas purification catalyst or the particulate filter, the exhaust gas pressure varies greatly depending on the opening and closing of the exhaust throttle valve, and therefore it has a greater influence on the amount of delivered fuel.

Further indicates the fuel in the case of a higher temperature of the fuel a lower viscosity on, as in the case of a lower temperature of the fuel. Therefore will be the amount of fuel flowing during the same valve opening time actually in the exhaust passage is delivered larger when the fuel temperature increases.

As mentioned above The amount of fuel that varies from the fuel addition valve varies is supplied in the exhaust passage, depending on the exhaust pressure and the Fuel temperature. Therefore, not always fuel in the required amount supplied to the NOx adsorption catalyst, causing problems such as insufficient conversion of NOx by the NOx adsorption catalyst in harmless Substances, an insufficient release of the adsorbed NOx, so that the purification capacity of the NOx adsorption catalyst decreases, and an excessive addition of fuel, so that the excess fuel is released into the atmosphere will, leads.

Disclosure of the invention

The The present invention has been made to solve the above-mentioned problems and has for its main object, an exhaust gas purification device for a To provide an internal combustion engine, which has an exhaust gas purification function can keep stable by providing an aid to preservation the emission control function required will be able to deliver exactly.

A Emission control device for an internal combustion engine according to the present invention comprises: an exhaust gas cleaning agent that is in an exhaust passage of the internal combustion engine is provided to exhaust gas emitted from the internal combustion engine, to clean; an aid delivery agent to aid to maintain the exhaust gas purification function of the exhaust gas purifier upstream of the To provide exhaust gas cleaning agent in the exhaust passage; a change factor parameter detection means, by the value of a change factor parameter, the changes caused in the amount of supplied aid to determine; and a control means for controlling the auxiliary supply means and thereby the amount of auxiliary agent entering the exhaust passage is supplied, the control means comprising a standard delivery quantity determination section, to the standard delivery quantity of the aid, which helps to preserve the Emission control function of the exhaust gas cleaning agent is needed, to determine; a destination delivery amount determination section to enter through a Correction of the standard delivery quantity determined by the standard delivery quantity determination section based on the value of the parameter determined by the variation factor parameter detection means it has been determined to determine the target delivery quantity of the auxiliary; and a delivery control section to the auxiliary delivery means to steer to the aid with the target delivery quantity, which by the destination delivery quantity determination section has been determined to deliver includes.

at the exhaust gas purification device for the internal combustion engine according to the present invention becomes the standard delivery quantity of the aid to maintain the emission control function the exhaust gas cleaning agent needed is corrected based on the value of the variation factor parameter and the aid in the thus corrected amount in delivered the exhaust passage. This allows the tool in exactly the amount to be delivered to the exhaust passage that is needed to preserve the exhaust gas purification function of the exhaust gas cleaning agent, whereby the influence of the change factor is prevented to the amount of the supplied aid.

Brief description of the drawings

1 Fig. 10 is a diagram showing the entire structure of an exhaust gas purification device for an internal combustion engine according to a first embodiment of the present invention;

2 is a block diagram for a control of the light oil supply by an electronic control unit ECU of 1 ;

3 is a flow chart illustrating the control of the light oil supply by the ECU of 1 shows;

4 FIG. 15 is a graph showing a characteristic of an exhaust pressure Pex correction factor Rp map generated by the ECU of FIG 1 is used;

5 FIG. 12 is a graph showing a characteristic of a light oil temperature Tf correction factor Rt map generated by the ECU of FIG 1 is used;

6 FIG. 12 is a graph showing a characteristic of a target delivery Mt duty cycle Dt map generated by the ECU of FIG 1 is used;

7 FIG. 10 is a block diagram for controlling the light oil supply in an exhaust gas purification device for an internal combustion engine according to FIG second embodiment of the present invention;

8th FIG. 15 is a diagram showing the schematic structure of an exhaust gas purification device for an internal combustion engine according to a third embodiment of the present invention; FIG.

9 is a block diagram for the control of urea water supply in the exhaust gas purification device of 8th ;

10 FIG. 11 is a flowchart showing the control of the urea water supply in the exhaust gas purification device of FIG 8th shows;

11 FIG. 15 is a graph showing a characteristic of an exhaust pressure Pex correction factor Rp map used in the control of the urea water supply in the exhaust gas purification device of FIG 8th is used;

12 FIG. 15 is a graph showing a characteristic of a urea water temperature Tu correction factor Rp map used in the control of urea water supply in the exhaust gas purification device of FIG 7 is used;

13 Fig. 10 is a diagram showing the schematic structure of an exhaust gas purification device for an internal combustion engine according to a fourth embodiment of the present invention; and

14 is a block diagram illustrating the control of the light oil supply in the exhaust gas purification device of 13 shows.

The best way to execute the invention

Under Reference will now be made to embodiments of the attached drawings of the present invention.

1 Fig. 10 shows the system structure of a four-cylinder diesel engine (hereinafter referred to as engine) to which an exhaust gas purification device according to a first embodiment of the present invention is attached. With reference to 1 the structure of the exhaust gas purification device according to the present invention will be described.

As in 1 shown is the engine 1 a four-cylinder diesel series engine in which fuel is supplied directly into each cylinder through a fuel injection valve (not shown) provided for each cylinder.

A turbocharger 4 is at a suction passage 2 provided. Intake air sucked in by an air cleaner (not shown) flows from the intake passage 2 to a compressor 4a of the turbocharger 4 , After passing through the compressor 4a was compressed, the intake air through an intercooler 6 guided and then into an intake manifold 8th brought in.

At the intake passage 2 is upstream of the compressor 4a an airflow sensor 10 for determining the amount of intake air flow to the engine 1 provided. Further, in the intake passage 2 downstream of the intercooler 6 an intake throttle valve 12 to regulate the amount of intake air in the engine 1 is admitted.

Exhaust ports (not shown) through the exhaust from the respective cylinders of the engine 1 are emitted through an exhaust manifold 14 with an exhaust pipe (an exhaust passage) 16 connected. An exhaust gas recirculation passage 20 is provided to the exhaust manifold 14 and the intake manifold 8th to connect, being between the exhaust manifold 14 and the intake manifold 8th an exhaust gas recirculation valve 18 is arranged.

The exhaust pipe 16 is through a turbine 4b of the turbocharger 4 with an exhaust aftertreatment device 22 connected. The turbine 4b is with the compressor 4a coupled and receives exhaust gas, that in the exhaust pipe 16 flows, causing the compressor 4a is driven.

The exhaust aftertreatment device 22 has a housing in which a NOx adsorption catalyst 24 is arranged as an exhaust gas purifier on the upstream side and a DPF (Diesel Particulate Filter) 26 on the downstream side of the NOx adsorption catalyst 24 is arranged. The NOx adsorption catalyst has the function of adsorbing NOx contained in the exhaust gas when the exhaust gas air-fuel ratio is lean, and releasing and reducing the adsorbed NOx when the exhaust gas air-fuel Ratio is fat. The NOx adsorption catalyst 24 who has this function is publicly known. The DPF 26 has the function to catch particulate matter contained in the exhaust gas. The exhaust gas that passes through the NOx adsorption catalyst 24 and the DPF 26 was cleaned, is released into the atmosphere.

Upstream of the exhaust aftertreatment device 22 is an exhaust throttle valve 28 provided, which acts as an exhaust brake, and upstream of the exhaust throttle valve 28 is an exhaust pressure sensor (an exhaust pressure detecting means) 30 for determining the exhaust gas pressure in the exhaust pipe 16 provided.

Further, upstream of the exhaust throttle valve 28 a light oil additive valve (an auxiliary delivery agent) 32 for the injection of light oil, which is the same fuel as the engine 1 is delivered as an aid in the exhaust pipe 16 to make the exhaust gas air-fuel ratio rich, to cause the NOx adsorption catalyst to release and reduce the adsorbed NOx. The light oil additive valve 32 is a solenoid valve designed to be opened by energizing a solenoid to inject light oil, and to be closed by adjusting the energization of the solenoid to adjust the supply of the light oil. Therefore, when the light oil pressure is fixed, light oil in the amount becomes into the exhaust pipe 16 delivered at the time of energization of the light oil additive valve 32 is proportional.

The light oil is passed through a light oil delivery passage 34 to the light oil additive valve 32 delivered. At the light oil delivery passage 34 is a light oil temperature sensor (an auxiliary agent temperature detecting means) 36 to determine the temperature of the light oil, the light oil additive valve 32 is provided.

An ECU (a control means) 38 is a control device for carrying out the general control of the exhaust gas purification device according to the present invention including the control of the engine 1 , The ECU includes a CPU, memory devices, timing counter, etc., and determines the values of a variety of control variables including the fuel delivery amount for each cylinder, and controls a variety of devices based on the determined values of the control variables.

To the entrance of the ECU 38 is a variety of sensors including the airflow sensor 10 , the exhaust pressure sensor 30 and the light oil temperature sensor 36 connected to collect information needed for a variety of controls. To the output of the ECU 38 is a variety of devices including the fuel injector (not shown) for each cylinder and the light oil supplement valve 32 which devices are controlled based on the determined values of the control variables.

In the exhaust gas purification device for the internal combustion engine having the structure described above, exhaust gas is generated during the operation of the engine 1 from the engine 1 is discharged through the exhaust pipe 16 in the exhaust aftertreatment device 22 introduced where NOx contained in the exhaust gas through the NOx adsorption catalyst 24 is adsorbed, and particulate matter contained in the exhaust gas, through the DPF 26 is caught.

The removal of the fine dust is carried out as follows: Light oil is from the light oil additive valve 32 in the exhaust pipe 16 injected and the NOx adsorption catalyst 24 oxidized. The resulting high-temperature gas becomes a flow in the DPF 26 forced so that the fine dust passing through the DPF 26 was caught by oxidation from the DPF 26 Will get removed.

The NOx that is not adsorbed but remains in the exhaust gas, because the amount of NOx passing through the NOx adsorption catalyst 24 adsorbed, has reached the limit, enters the DPF 26 downstream of the NOx catalyst 24 and acts as an oxidant to control the particulate matter passing through the DPF 26 was caught, oxidize. Consequently, the particulate matter is oxidized by the DPF 26 removed while NOx entering the DPF 26 has flown, transformed into N ₂ , which is released into the atmosphere.

The conversion of the NOx is carried out in the following manner. By performing the lean operation, the NOx adsorption catalyst is caused to adsorb NOx contained in the exhaust gas. After the amount of NOx passing through the NOx adsorption catalyst 24 is adsorbed, has reached a certain degree, is light oil from the light oil additive valve 32 in the exhaust pipe 16 injected to make the exhaust air-fuel ratio rich. The NOx adsorption catalyst 24 supplied with a rich air-fuel ratio thus obtained, releases and reduces the adsorbed NOx, whereby the adsorption capacity of the NOx adsorption catalyst 24 is restored. After the regeneration of the NOx adsorption catalyst 24 is completed by the release and the reduction of the adsorbed NOx, the injection of light oil from the light oil additive valve 32 completed.

By appropriately repeating the regeneration of the NOx adsorption catalyst 24 and the DPF 26 becomes the exhaust gas purification function of the NOx adsorption catalyst 24 and the DPF 26 preserved.

Next, referring to 2 to 6 the control of the light oil supply from the light oil additive valve 32 to be discribed.

2 shows the design of control blocks for carrying out the control of the light oil supply in the ECU 38 , and 3 Fig. 10 is a flowchart showing the control of the light oil supply performed by these control blocks.

As in 2 shown includes the ECU 38 a standard delivery quantity determination section 40 to determine the standard delivery quantity Mb of light oil needed to cause that the NOx adsorption catalyst 24 that through the NOx adsorption catalyst 24 adsorbed NOx releases and reduces, thereby increasing the NOx adsorption capacity of the NOx adsorption catalyst 24 is preserved; a destination delivery quantity determination section 42 to correct by the standard delivery quantity determination section 40 determined standard delivery quantity based on the exhaust pressure Pex, by the exhaust pressure sensor 30 and the light oil temperature Tf detected by the light oil temperature sensor 36 it is determined to determine the target delivery quantity Mt; and a delivery control section 44 to the light oil additive valve 32 so as to control that light oil in the target delivery amount Mt passing through the target delivery quantity determination section 42 was determined to be delivered to the exhaust passage.

More specifically, the intake air flow rate Qa flowing through the airflow sensor 10 is determined, and the engine rotation speed Ne, by the rotational speed sensor 46 is determined to the standard Liefermengenbestim determination section 40 led, and becomes the standard delivery amount Mb of light oil, which is needed to cause the NOx adsorption catalyst 24 releases and reduces the adsorbed NOx, based on the intake air flow rate Qa and the engine rotation speed Ne, from a map stored in advance (step S10 in FIG 3 ).

The standard delivery quantity Mb, which is determined by the standard delivery quantity determination section 40 has been determined becomes the destination delivery quantity determination section 42 Posted. The exhaust gas pressure Pex flowing through the exhaust pressure sensor 30 is determined, and the light oil temperature Tf, by the light oil temperature sensor 36 is determined become the target delivery quantity determination section 42 and the destination delivery quantity determination section 42 corrects the default delivery amount Mb based on the exhaust pressure Pex and the light oil temperature Tf.

The amount of light oil that comes from the light oil additive valve 32 is adjusted by varying its valve opening time, the amount of fuel flowing into the exhaust pipe 16 is injected, increases as the valve opening time becomes longer. Accordingly, when the light oil discharge pressure is fixed, the amount of light oil actually entering the exhaust pipe during the same valve opening time becomes 16 is supplied, lower as the exhaust gas pressure increases. Further, in the case of a higher temperature of the light oil, the light oil has a lower viscosity than in the case of a lower temperature of the light oil. This will reduce the amount of light oil that enters the exhaust pipe during the same valve opening time 16 is higher when the light oil temperature increases.

Therefore, in conjunction with the exhaust pressure Pex, a correction factor Rp corresponding to the detected exhaust pressure Pex is determined from a map stored in advance (step S12 in FIG 3 ), where the plan is created so that the correction factor Rp as in 4 shown decreases with the increase of the exhaust pressure Pex. The target delivery quantity determination section 42 corrects the standard delivery amount Mb by dividing the standard delivery amount Mb by the correction factor Rp to obtain a pressure corrected delivery amount Mp (step S14 in FIG 3 ).

It should be noted that the correction factor Rp in a standard state, in which the exhaust pressure is equal to the exhaust pressure value, on the basis thereof the plan is created to determine the default delivery quantity Mb is set to 1.0.

By the correction of the standard delivery quantity Mb using the correction factor Rp in this way, the pressure-corrected delivery quantity Mp is greater than the default delivery amount Mb when the exhaust pressure Pex is higher than the exhaust pressure value is in the standard state. Therefore, a shortfall of the Delivered quantity compensated due to an increase in the exhaust pressure Pex. Conversely, the pressure-corrected delivery quantity Mp is smaller than the Default delivery quantity Mb, if the exhaust pressure Pex lower than the Exhaust pressure value is in the standard state. Therefore, a surplus in the delivery quantity due to a decrease in the exhaust pressure Pex prevented.

Next, in conjunction with the light oil temperature Tf, a correction factor Rt corresponding to the detected light oil temperature Tf is determined from a map stored in advance (step S16 in FIG 3 ), where the plan is made so that the correction factor Rt is as in 5 shown increases as the light oil temperature increases. The target delivery quantity determination section 42 corrects the pressure-corrected delivery amount Mp by dividing the pressure-corrected delivery amount Mp by the correction factor Rt to obtain the target delivery amount Mt (step S18 in FIG 3 ).

It should be noted that the correction factor Rt in a standard state, in which the light oil temperature equal to the light oil temperature value on the basis of which the plan is drawn up for determination the default delivery quantity Mb is set to 1.0.

Here, the correction is made using the correction factor Rt at the pressure-corrected delivery amount Mp. However, since the pressure-corrected delivery quantity Mp as mentioned above is the correction of the standard delivery quantity Mb on the basis of the Exhaust pressure Pex, the correction is actually made using the correction factor Rt at the standard delivery quantity Mb. Accordingly, by correcting the pressure-corrected delivery amount Mp, or actually the standard delivery amount Mb, using the correction factor Mt in this way, the target delivery amount Mt becomes smaller as the light oil temperature Tf increases, and thereby an excess in the delivery amount is avoided by an increase in the light oil temperature Tf. Conversely, the target delivery amount Mt becomes larger as the light oil temperature Tf decreases, thereby offsetting the shortfall in the delivery amount due to a drop in the light oil temperature Tf.

In the flowchart of 3 At step S12 and step S14, first, the pressure-corrected delivery amount Mp is obtained by correcting the default delivery amount Mb based on the exhaust pressure Pex, and then at step S16 and S18, determining the target delivery amount Mt by correcting the pressure-corrected delivery amount Mp based on the light oil temperature. It should be noted, however, that the order of the steps is not limited to this order.

To the Example can steps S12 and S14 are interchanged with steps S16 and S18 become. In particular, such an embodiment is possible that first a temperature-corrected Delivery quantity is obtained by the standard delivery quantity Mb below Use of the correction factor Rt, the light oil temperature Tf is corrected, and then the target delivery amount Mt is obtained by using the temperature-corrected delivery amount of the correction factor Rp corresponding to the exhaust pressure Pex is corrected becomes.

alternative is such an embodiment possible, first, the correction factor Rp corresponding to the exhaust gas pressure Pex and the correction factor Rt, which corresponds to the light oil temperature Tf, determined from the respective schedules, and then the target delivery quantity Mt is obtained by changing the default delivery quantity Mb one by one divided by the correction factors Rp and Rt.

Even though the correction in the case described above by dividing the standard delivery quantity Mb, the pressure-corrected delivery quantity Mp or the temperature-corrected Delivery quantity by the correction factor Rp or the correction factor Furthermore, such an embodiment is possible that one out in advance stored plan the reciprocal of each correction factor will, so the correction by multiplying the delivery quantity is made with the reciprocal.

After the target delivery amount Mt of the light oil needed to cause the NOx adsorption catalyst 24 the adsorbed NOx is released and reduced, thus determined, the delivery control section determines 44 from a plan stored in advance, the valve opening time of the light oil additive valve 32 which is necessary for the light oil additive valve 32 Injecting light oil in the target delivery amount Mt (step S20 in FIG 3 ). As the control of the light oil additive valve 32 is performed in control cycles of a predetermined duration, the plan is created so that it the valve opening time of the light oil additive valve 32 that corresponds to the target delivery quantity Mt, as in 6 indicated in the form of a duty cycle Dt with respect to the maximum valve opening time in a control cycle.

After the determination of the duty cycle Dt corresponding to the target delivery amount Mt from the schedule, the delivery control section drives 44 the light oil additive valve 32 such that it opens according to the duty cycle Dt (step S22 in FIG 3 ), so that light oil in an amount equal to the target delivery amount Mt, from the light oil additive valve 32 in the exhaust pipe 16 is injected. This makes the exhaust air-fuel ratio rich, so that NOx passing through the NOx adsorption catalyst 24 was adsorbed, released properly and reduced.

It should be noted that the exhaust pressure sensor 30 upstream of the exhaust throttle 28 is arranged. This makes light oil even when the pressure in the exhaust pipe 16 by opening and closing the exhaust throttle 28 fluctuates, despite changes in the pressure in the exhaust pipe 16 always delivered properly in the amount needed to cause the NOx adsorption catalyst 24 the adsorbed NOx releases and reduces, as the standard delivery amount Mb as mentioned above, based on the exhaust pressure generated by this exhaust pressure sensor 30 is determined, is corrected.

As described above, in the exhaust gas purification device according to the first embodiment of the present invention, the amount of supply of light oil needed to cause the NOx adsorption catalyst 24 the adsorbed NOx releases and reduces, thereby preserving the NOx adsorption capacity of the NOx adsorption catalyst, properly controlled without being affected by changes in the exhaust pressure and the light oil temperature. As a result, the exhaust gas purification function can be stably maintained and the discharge of excess light oil into the atmosphere can be prevented.

Although the target delivery amount Mt in the exhaust gas purification device according to the first embodiment described above is a correction of the standard delivery amount Mb of the light oil required to the NOx adsorption capacity of the NOx adsorption catalyst 24 to preserve, based on that Although the exhaust pressure Pex and the light oil temperature Tf are determined, it should be noted that the correction can be made based on one of them. In this case, the control accuracy is lower compared to the making of the correction on the basis of both the exhaust pressure Pex and the light oil temperature Tf, but higher compared to the conventional exhaust gas purification device that takes neither the exhaust pressure nor the light oil temperature into consideration.

Further, although the standard delivery amount Mb of the light oil needed to cause the NOx adsorption catalyst 24 In the above-described first embodiment, if the adsorbed NOx is released and reduced based on the intake air flow rate Qa and the engine rotation speed Ne from a map stored in advance, the manner of determining the default delivery amount Mb is not limited thereto. For example, the default delivery amount Mb may be determined based on a decrease in NOx adsorption capacity that may be detected by a NOx sensor downstream of the NOx adsorption catalyst 24 is provided. There are a variety of known techniques that can be used.

Even though Further, the above-described first embodiment of the present invention Invention is an exhaust gas purification device that is based on a diesel engine is applied, it is not limited to the diesel engine, but applicable to any type of engine, the NOx adsorption catalyst used. In the case of a gasoline engine, instead of light oil, gasoline is used used as an aid.

The NOx adsorption catalyst 24 used in the above-described exhaust gas purification device according to the first embodiment adsorbs SOx (sulfur oxides) generated by the combustion of sulfur in the fuel, resulting in deterioration of the NOx adsorption function. Therefore, it is necessary to restore the NOx adsorption function, which has deteriorated, by causing the NOx adsorption catalyst 24 the SOx that passes through the NOx adsorption catalyst 24 adsorbed, releases. The SOx that passes through the NOx adsorption catalyst 24 can be adsorbed, from the NOx adsorption catalyst 24 be released by the temperature of the NOx adsorption catalyst 24 is increased, and the temperature of the NOx adsorption catalyst 24 can be increased by adding light oil through the light oil additive valve 32 used in the first embodiment, to the NOx adsorption catalyst 24 delivered and burned.

Next, as a second embodiment of the present invention, an exhaust gas purification device designed to release the SOx passing through the NOx adsorption catalyst will be described 24 was adsorbed to release in this way.

Because the entire system structure as in 1 is the same as in the first embodiment, the same reference numerals will be used for the same elements as those in the first embodiment, the detailed explanation of which will be omitted, and will hereafter mainly essential elements that are different from the first Different embodiment, will be described.

7 shows the design of control blocks that are in an ECU (a control means) 38 which performs the control of the supply of oil for the release of the SOx.

As in 7 shown includes the ECU 38 a standard delivery quantity determination section 50 to determine the standard delivery amount Mb of the fuel needed to cause the NOx adsorption catalyst 24 Sulfur compounds passing through the NOx adsorption catalyst 24 are released, whereby the deteriorating NOx adsorption capacity is restored; a destination delivery quantity determination section 52 by correcting the standard delivery amount Mb by the standard delivery quantity determination section 50 was determined based on the exhaust pressure, by the exhaust pressure sensor 30 and the light oil temperature Tf detected by the light oil temperature sensor 36 it is determined to determine the target delivery quantity Mt; and a delivery control section 54 to the light oil additive valve 32 so as to control that light oil in the target delivery amount Mt passing through the target delivery quantity determination section 52 was determined to be delivered to the exhaust passage.

An exhaust gas temperature sensor 48 for determining the temperature of the exhaust gas containing the NOx adsorption catalyst 24 is to the standard delivery quantity determination section 50 connected. The standard delivery quantity determination section 50 estimates the SOx accumulation amount, ie, the amount of SOx passing through the NOx adsorption catalyst 24 was adsorbed, from the cumulative fuel delivery amount for each cylinder, in the ECU 38 is calculated, and determines the standard delivery amount Mb of the light oil needed to the temperature of the NOx adsorption catalyst 24 to increase to an optimum temperature (for example 600 ° C) for releasing the SOx based on this estimated SOx accumulation amount and the exhaust gas temperature Tex flowing through the exhaust gas temperature sensor 48 is determined from a pre-stored secured plan.

As in the first embodiment described above, the correction of the standard delivery amount Mb made by the standard delivery amount determination section 50 was determined, and the control of light oil injection from the light oil additive valve 32 is executed according to a flowchart that the same steps as the steps S12 to S22 of the flowchart of 3 includes.

Specifically, the target delivery quantity determination section obtains 52 the standard delivery quantity Mb from the standard delivery quantity determination section 50 and corrects the default delivery amount Mb based on the exhaust pressure Pex provided by the exhaust pressure sensor 30 and the light oil temperature Tf detected by the light oil temperature sensor 36 is detected.

The correction of the standard delivery amount Mb is performed in the same manner as in the first embodiment. In conjunction with the exhaust pressure Pex, a correction factor corresponding to the detected exhaust pressure Pex is determined from a map stored in advance (step S12 in FIG 3 ), where the plan is created so that the correction factor Rp as in 4 shown decreases with the increase of the exhaust pressure Pex. The target delivery quantity determination section 52 corrects the standard delivery amount Mb by dividing the standard delivery amount Mb by the correction factor Rp to obtain a pressure corrected delivery amount Mp (step S14 in FIG 3 ).

By the correction of the standard delivery quantity Mb using the correction factor Rp in this way, the pressure-corrected delivery quantity Mp is greater than the default delivery amount Mb when the exhaust pressure Pex is higher than the exhaust pressure value of the standard state is. Therefore, a shortfall of the Delivered quantity compensated due to an increase in the exhaust pressure Pex. Conversely, the pressure-corrected delivery quantity Mp is smaller than the Default delivery quantity Mb, if the exhaust pressure Pex lower than the Exhaust pressure value of the standard state. Therefore, a surplus in the delivery quantity due to a decrease in the exhaust pressure Pex prevented.

In conjunction with the light oil temperature Tf, a correction factor Rt corresponding to the detected light oil temperature Tf is determined from a map stored in advance (step S16 in FIG 3 ), where the plan is made so that the correction factor Rt is as in 5 shown increases as the light oil temperature increases. The target delivery quantity determination section 52 corrects the pressure-corrected delivery amount Mp by dividing the pressure-corrected delivery amount Mp by the correction factor Rt to obtain the target delivery amount Mt (step S18 in FIG 3 ).

Here the correction is made using the correction factor Rt at the pressure-corrected delivery quantity Mp made. But because the pressure corrected Delivery quantity Mp as mentioned in relation to the first embodiment the correction of the standard delivery quantity Mb based on the exhaust pressure Pex results, the correction is made using the correction factor Rt actually made on the standard delivery quantity Mb. Accordingly, by a Correction of the pressure-corrected delivery quantity Mp, or actually the standard delivery quantity Mb, using the correction factor Mt in this way the target delivery Mt less if the light oil temperature Tf increases. This will be a surplus in the delivery amount due to an increase in light oil temperature Tf avoided. Conversely, the target delivery quantity Mt becomes larger when the light oil temperature Tf decreases. This will cause the shortage of delivery quantity due a drop in the light oil temperature Tf balanced.

It should be noted that the order of steps S12, S14 and steps S16, S16 in the flowchart of FIG 3 as in the first embodiment is not limited to this order.

Even though the correction in the case described above by dividing the standard delivery quantity Mb, the pressure-corrected delivery quantity Mp or the temperature-corrected Delivery quantity by the correction factor Rp or the correction factor Furthermore, such an embodiment is possible that from a stored Plan the reciprocal of each correction factor is obtained, so that the correction by multiplying the delivery quantity by the reciprocal is made.

After the target delivery amount Mt of the light oil needed to cause the NOx adsorption catalyst 24 the adsorbed SOx releases, thus determined, the delivery control section determines 54 from a plan stored in advance, the valve opening time of the light oil additive valve 32 which is necessary for the light oil additive valve 32 Light oil in the target delivery amount Mt as in the first embodiment in the form of a duty cycle Dt (step S20 in FIG 3 ) injects.

After the determination of the duty cycle Dt corresponding to the target delivery amount Mt from the schedule, the delivery control section drives 54 the light oil additive valve 32 such that it opens according to the thus-determined duty cycle Dt (step S22 in FIG 3 ), so that light oil in an amount equal to the target delivery amount Mt, from the Leichtölzusatzven til 32 in the exhaust pipe 16 is injected. Due to the exhaust heat, the light oil in the exhaust gas breaks down into HC, which reaches and burns the NOx adsorption catalyst. This causes a temperature rise of the NOx adsorption catalyst 24 , allowing SOx to pass through the NOx adsorption catalyst 24 adsorbed properly, and the NOx adsorption capacity of the NOx adsorption catalyst 24 is restored.

As described above, in the exhaust gas purification device according to the second embodiment of the present invention, the amount of supply of light oil required to cause the NOx adsorption catalyst 24 the adsorbed SOx releases, thereby keeping the NOx adsorption capacity of the NOx adsorption catalyst, properly controlled without being affected by changes in the exhaust pressure and the light oil temperature. Thereby, the exhaust gas purification function of the NOx adsorption catalyst 24 stable and prevent the release of excess light oil into the atmosphere.

Although the target delivery amount Mt in the exhaust gas purification device according to the second embodiment is a correction of the standard delivery amount Mb of the light oil needed to the NOx adsorption capacity of the NOx adsorption catalyst 24 is determined based on both the exhaust gas pressure Pex and the light oil temperature Tf, it should be noted that the correction can be made based on one of them. In this case, the control accuracy is lower compared to the making of the correction on the basis of both the exhaust pressure Pex and the light oil temperature Tf, but higher compared to the conventional exhaust gas purification device that takes neither the exhaust pressure nor the light oil temperature into consideration.

Further, although the standard delivery amount Mb of the light oil needed to cause the NOx adsorption catalyst 24 In the above-described case, if the adsorbed SOx is released based on the cumulative fuel delivery amount for each cylinder and the exhaust gas temperature Tex is determined from a map stored in advance, the manner of determining the default delivery amount Mb is not limited thereto. There are a variety of known techniques that can be used.

It is also possible to carry out the first embodiment of the exhaust gas purification device for performing the SOx release control in the second embodiment as well, that the supply of the light oil for the release and the reduction of the NOx and the supply of the light oil for the release of the SOx both through the same light oil additive valve 32 be executed.

Even though Further, the above-described first embodiment of the present invention Invention is an exhaust gas purification device that is based on a diesel engine is applied, it is not limited to the diesel engine, but applicable to any type of engine, the NOx adsorption catalyst used. In the case of a gasoline engine, instead of light oil, gasoline is used used as an aid.

Hereinafter, referring to 8th to 11 A third embodiment of the present invention will be described.

8th shows the structure of an exhaust gas purification device according to the third embodiment of the present invention. The structure of an engine constituting a basis for the exhaust gas purification device and an intake system of the engine is the same as that for the first embodiment. In 8th For example, the same reference numerals are used for the same elements as those of the first embodiment.

In an exhaust pipe 16 Assembled to an exhaust manifold (not shown) of an engine, a turbine (not shown) of a turbocharger is housed, and downstream of the turbine is a selective reduction type NOx catalyst (hereinafter referred to as an SCR catalyst). 56 as an exhaust gas cleaning agent to the exhaust pipe 16 connected. The SCR catalyst 56 promotes the denitration reaction between ammonia and NOx contained in the exhaust gas to selectively reduce NOx, namely, to convert NOx into harmless substances.

An exhaust throttle valve 28 acting as an exhaust brake is upstream of the SCR catalyst 56 provided, and an exhaust pressure sensor (an exhaust pressure detecting means) 30 for determining the exhaust gas pressure in the exhaust pipe 16 is upstream of the exhaust throttle valve 28 provided.

To supply the ammonia needed to convert the NOx to the SCR catalyst 56 is upstream of the exhaust throttle valve 28 a urea water additive valve (a tool delivery) 58 for the injection of urea water as an aid in the exhaust pipe 16 provided. The urea water additive valve 58 is a solenoid valve designed to be opened by energizing a solenoid to inject urea water, and to be closed by adjusting the energization of the solenoid to adjust the supply of the urea water. Therefore, when the urea water supply pressure is fixed, urea water in the amount becomes into the exhaust pipe 16 delivered, which is the time of energizing the urine material water additional valve 58 equivalent.

By the heat of the exhaust gas becomes the urea water, that of the urea water addition valve 58 in the exhaust pipe 16 is hydrolyzed to ammonia, the SCR catalyst 56 is supplied and used to convert the NOx.

Urea water is supplied from a urea water storage tank (not shown) through a urea water supply passage 60 to the urea water additive valve 58 delivered. At the urea water passage 60 is a urea water temperature sensor (an auxiliary agent temperature detecting means) 62 for determining the temperature of the urea water, the urea water addition valve 58 is provided.

At the exhaust pipe 16 is upstream of the SCR catalyst 56 a sensor 64 for the upstream exhaust gas temperature for determining the temperature of the exhaust gas, which is the SCR catalyst 56 enters, provided. Furthermore, the exhaust pipe 16 downstream of the SCR catalyst 56 a sensor 66 for the exhaust gas downstream temperature for determining the temperature of the exhaust gas containing the SCR catalyst 56 leaves, provided.

As with the first embodiment described above, a variety of sensors including the exhaust pressure sensor 30 , the urea water temperature sensor 62 , the sensor 64 for the upstream exhaust gas temperature and the sensor 66 for the downstream exhaust gas temperature to the input of an ECU (a control means) 38 , which is a control device for performing the general control of the exhaust gas purification device according to the present invention including the control of the engine, connected to collect information needed for a variety of controls. To the output of the ECU 38 is a variety of devices including the fuel injector (not shown) for each cylinder and the urea supplement valve 58 connected, which devices are controlled based on values of the control variables stored in the ECU 38 be determined.

In the exhaust gas purification device having the above-described structure, exhaust gas discharged from the engine is exhausted through the exhaust pipe 16 introduced into the SCR catalyst while the urea water from the urea water addition valve 58 in the exhaust pipe 16 is injected due to the heat of the exhaust gas to ammonia, and the ammonia to the SCR catalyst 56 is delivered. On the SCR catalyst 56 That is, the denitration reaction between the ammonia and the NOx in the exhaust gas is promoted, so that NOx is converted into harmless substances.

By doing so urea water as an aid in the exhaust pipe 16 is delivered, the exhaust gas purification function of the SCR catalyst 56 preserved.

Next, referring to 9 to 12 the control of the urea water supply from the urea water addition valve 58 to be discribed.

9 shows the design of control blocks used in the ECU 38 are arranged to perform the control of urea water supply, and 10 Fig. 10 is a flow chart showing the control of the urea water supply.

As in 9 shown includes the ECU 38 a standard delivery quantity determination section 68 to determine the standard delivery quantity Mb of urea water needed for the SCR catalyst 56 NOx, which is contained in the exhaust gas, selectively reduced; a destination delivery quantity determination section 70 to correct by the standard delivery quantity determination section 68 determined standard delivery quantity Mb based on the exhaust pressure Pex, by the exhaust pressure sensor 30 and the urea water temperature Tu detected by the urea water temperature sensor 62 it is determined to determine the target supply amount Mt; and a delivery control section 72 to the urea water addition valve 58 so as to control urea water in the target delivery amount Mt passing through the target delivery quantity determination section 70 was determined in the exhaust pipe 16 is delivered.

Specifically, the exhaust gas temperature Texu becomes upstream of the SCR catalyst 56 passing through the temperature sensor 64 is determined for the upstream exhaust gas temperature, the exhaust gas temperature Texd downstream of the SCR catalyst 56 passing through the temperature sensor 66 for the downstream exhaust gas temperature, and the engine rotation speed Ne detected by the revolution speed sensor 46 is determined to the standard delivery quantity determination section 68 guided. Based on the amount of fuel supplied to each cylinder in the ECU 38 is calculated, the estimated NOx emission amount and the NOx conversion rate, which are determined from previously stored plans, the exhaust gas temperature Texu, the exhaust gas temperature Texd and the engine rotation speed Ne, which are supplied from the above-mentioned sensors, etc., the standard supply amount Mb of the urea water needed for the SCR catalyst 56 NOx, which is contained in the exhaust gas, is selectively reduced, determined from a map stored in advance (step S110 in FIG 10 ).

The above-mentioned technique for the standard delivery quantity determination section 68 for the determination of the standard delivery quantity Mb is publicly known, and the way of determining the standard delivery quantity Mb of the urea water that is needed so that the SCR catalyst 56 NOx selectively contained in the exhaust gas is not limited to this.

The standard delivery quantity Mb, which is determined by the standard delivery quantity determination section 68 has been determined becomes the destination delivery quantity determination section 70 Posted. The exhaust gas pressure Pex flowing through the exhaust pressure sensor 30 and the urea water temperature Tu detected by the urea water temperature sensor 62 is determined become the target delivery quantity determination section 70 and the destination delivery quantity determination section 70 corrects the default delivery amount Mb based on the exhaust pressure Pex and the urea water temperature Tu.

As in the first embodiment, the amount of urea water is that of the urea water addition valve 58 is delivered by changing the valve opening time of the urea water addition valve 58 regulated, with the amount of urea water flowing into the exhaust pipe 16 increases as the valve opening time becomes longer. Accordingly, when the urea water supply pressure is fixed, the amount of urea water actually entering the exhaust pipe during the same valve opening time becomes 16 is supplied, lower as the exhaust gas pressure increases. Further, in the case of a higher temperature of the urea water, the urea water has a lower viscosity than in the case of a lower temperature of the urea water. Accordingly, the amount of urea water entering the exhaust pipe during the same valve opening time 16 is higher, when the urea water temperature increases.

Therefore, in conjunction with the exhaust pressure Pex, a correction factor Rp corresponding to the detected exhaust pressure Pex is determined from a map stored in advance (step S112 in FIG 10 ), where the plan is created so that the correction factor Rp as in 11 shown decreases with the increase of the exhaust pressure Pex. The target delivery quantity determination section 70 corrects the standard delivery amount Mb by dividing the standard delivery amount Mb by the correction factor Rp to obtain a pressure-corrected delivery amount Mp (step S114 in FIG 10 ).

It should be noted that the correction factor Rp in a standard state, in which the exhaust pressure is equal to the exhaust pressure value, on the basis thereof the plan is created to determine the default delivery quantity Mb is set to 1.0.

By the correction of the standard delivery quantity Mb using the correction factor Rp in this way, the pressure-corrected delivery quantity Mp is greater than the default delivery amount Mb when the exhaust pressure Pex is higher than the exhaust pressure value of the standard state is. Therefore, a shortfall of the Delivered quantity compensated due to an increase in the exhaust pressure Pex. Conversely, the pressure-corrected delivery quantity Mp is smaller than the Default delivery quantity Mb, if the exhaust pressure Pex lower than the Exhaust pressure value of the standard state. Therefore, a surplus in the delivery quantity due to a decrease in the exhaust pressure Pex prevented.

Next, in conjunction with the urea water temperature Tu, a correction factor Rt corresponding to the detected urea water temperature Tu is determined from a map stored in advance (step S116 in FIG 10 ), where the plan is made so that the correction factor Rt is as in 12 shown increases as the urea water temperature increases. The target delivery quantity determination section 70 corrects the pressure-corrected delivery amount Mp by dividing the pressure-corrected delivery amount Mp by the correction factor Rt to obtain the target delivery amount Mt (step S118 in FIG 10 ).

It should be noted that the correction factor Rt in a standard state, in which the urea water temperature is the urea water temperature value is equal, on the basis of which the plan is drawn up for the determination the default delivery quantity Mb is set to 1.0.

Here the correction is made using the correction factor Rt at the druckkorri gierten delivery quantity Mp made. But because the pressure corrected Delivery quantity Mp as mentioned above from the correction of the standard delivery quantity Mb based on the exhaust pressure Pex results, the correction is made using the correction factor Rt actually made on the standard delivery quantity Mb. Accordingly, by a correction of the pressure-corrected delivery quantity Mp, or actually the standard delivery quantity Mb, using the correction factor Mt in this way, the target delivery amount Mt smaller, if the urea water temperature Tu increases. This will be a surplus in the delivery amount due to an increase in urea water temperature Avoid it. Conversely, the target delivery quantity Mt becomes larger when the urea water temperature Tu decreases. This will be the underfunding the delivery amount due to a drop in urea water temperature Tu balanced.

In the flowchart of 10 As mentioned above, at step S112 and step S114, the pressure corrected supply quantity Mp is obtained by correcting the standard delivery amount Mb based on the exhaust pressure Pex, and then, at step S116 and S118, the target delivery amount Mt is determined by correcting the pressure corrected delivery amount Mp based on the urea water temperature. It should be noted, however, that the order of the steps as in the first embodiment is not limited to this order.

To the Example can the steps S112 and S114 are exchanged with the steps S116 and S118. In particular, such an embodiment is possible that first a temperature-corrected Delivery quantity is obtained by the standard delivery quantity Mb below Using the correction factor Rt, the urea water temperature Tu corresponds, is corrected, and then the target delivery amount Mt is obtained by the temperature-corrected delivery quantity below Use of the correction factor Rp, which corresponds to the exhaust gas pressure Pex, is corrected.

alternative is such an embodiment possible, first, the correction factor Rp corresponding to the exhaust gas pressure Pex and the correction factor Rt, that of the urea water temperature Tu is determined from the respective plans, and then the target delivery quantity Mt is obtained by the standard delivery quantity Mb is divided successively by the correction factors Rp and Rt.

Even though the correction in the case described above by dividing the standard delivery quantity Mb, the pressure-corrected delivery quantity Mp or the temperature-corrected Delivery quantity by the correction factor Rp or the correction factor Furthermore, such an embodiment is possible that from a stored Plan the reciprocal of each correction factor is obtained, so that the correction by multiplying the delivery quantity by the reciprocal is made.

After the target delivery amount Mt of urea water, which is needed, so that the SCR catalyst 24 NOx is selectively reduced, thus determined, the delivery control section determines 72 from a pre-stored schedule, the valve opening time of the urea water addition valve 58 which is necessary for the urea water addition valve 58 Urea water in the target delivery amount Mt injects (step 120 in 10 ). As the control of the urea water addition valve 58 As in the first embodiment, in control cycles of a predetermined duration, the schedule is made to be the valve opening time of the urea water addition valve 58 , which corresponds to the target delivery amount Mt, in the form of a duty cycle Dt with respect to the maximum valve opening time in one control cycle. Although a graphical illustration has been omitted, the relationship between the target delivery amount Mt and the duty cycle Dt is a proportional relationship that is the one in 6 similar to the relationship shown in the first embodiment.

After the determination of the duty cycle Dt corresponding to the target delivery amount Mt from the schedule, the delivery control section drives 72 the urea water additive valve 58 such that it opens according to the duty cycle Dt (step S122 in FIG 10 ), so that urea water in an amount equal to the target delivery amount Mt from the urea water addition valve 58 in the exhaust pipe 16 is injected. By the heat of the exhaust gas is the urea water, in this way in the exhaust pipe 16 is hydrolyzed to ammonia, which acts as a reducing agent to NOx contained in the exhaust gas, on the SCR catalyst 56 selectively reduce.

It should be noted that the exhaust pressure sensor 30 upstream of the exhaust throttle valve 28 is arranged. This will allow urea water even if the pressure in the exhaust pipe 16 by opening and closing the exhaust throttle valve 28 fluctuates, despite changes in the pressure in the exhaust pipe 16 always delivered properly in the amount needed to allow the SCR catalyst 56 NOx is selectively reduced since the default delivery amount Mb is as mentioned above based on the exhaust pressure Pex flowing through this exhaust pressure sensor 30 is determined, is corrected.

As described above, in the exhaust gas purification device according to the third embodiment of the present invention, the amount of supply of urea water that is needed is the SCR catalyst 56 NOx, which is contained in the exhaust gas, is selectively reduced, thereby maintaining its NOx adsorption capacity, properly controlled without being affected by changes in the exhaust pressure and in the urea water temperature. Thereby, the exhaust gas purification function can be stably maintained and the discharge of excess urea water or ammonia into the atmosphere can be prevented.

Although the target delivery amount Mt in the above-described exhaust gas purification device according to the third embodiment is a correction of the standard delivery amount Mb of the urea water required, so that the NOx conversion capacity of the SCR catalyst 56 is determined based on both the exhaust pressure Pex and the urea water temperature Tu is determined, it should be noted that the correction can be made on the basis of one of them. In this case, the control accuracy is lower compared to the making of the correction on the basis of both the exhaust gas pressure Pex and the urea water temperature Tu, but compared with the conventional exhaust gas purifier tion device, which takes into account neither the exhaust pressure nor the urea water temperature, higher.

Even though Further, the above-described third embodiment of the present invention Invention is an exhaust gas purification device that is based on a diesel engine is applied, it is not limited to the diesel engine, but applicable to any type of engine that has an SCR catalyst used to selectively reduce NOx contained in the exhaust gas.

Next, referring to 13 to 14 an exhaust gas purification device according to a fourth embodiment of the present invention will be described.

13 shows the structure of an exhaust gas purification device according to the fourth embodiment of the present invention. The structure of an engine constituting a basis for the exhaust gas purification device and an intake system is the same as that for the first embodiment. In 13 For example, the same reference numerals are used for the same elements as those of the first embodiment.

In an exhaust pipe 16 Attached to an exhaust manifold (not shown) of an engine is a turbine (not shown) of a turbocharger, and downstream of the turbine is an exhaust aftertreatment device 74 to the exhaust pipe 16 connected.

The exhaust aftertreatment device 74 has a housing in which on the upstream side of an oxidation catalyst 76 is arranged and downstream of the oxidation catalyst 76 a DPF (Diesel Particulate Filter) 78 is arranged as an exhaust gas cleaning agent. The DPF 78 has a porous honeycomb structure made of ceramics, and has the function of trapping particulate matter contained in the exhaust gas as the exhaust gas flows therethrough.

The one by the DPF 78 trapped particulate matter accumulates at the DPF 78 , which is a gradual decrease in the fishing capacity of the DPF 78 and causing an increase in the resistance exerted on the flowing exhaust gas. Therefore, it is necessary to burn off the particulate matter when the accumulation of particulate matter reaches a certain level, thereby increasing the capacity of the DPF 78 is preserved. In order to increase the exhaust gas temperature to a level at which the particulate matter can be burned off, the oxidation catalyst becomes 76 used. In particular, light oil as an aid in a manner described later becomes the oxidation catalyst 76 delivered and burned, and this combustion of light oil increases the exhaust gas temperature, so that the fine dust that accumulates in the DPF 78 accumulated, is eliminated by burning.

At the aftertreatment device 74 are between the oxidation catalyst 76 and the DPF 78 an inlet temperature sensor 80 for determining the exhaust gas temperature Tin at the inlet side of the DPF 78 and an inlet pressure sensor 82 to determine the exhaust pressure Pin on the inlet side of the DPF 78 provided, and is downstream of the DPF 78 an outlet pressure sensor 84 for detecting the outlet pressure Pout at the outlet side of the DPF 78 provided.

Upstream of the exhaust aftertreatment device 74 is an exhaust throttle valve 28 , which acts as an exhaust brake, provided, and upstream of the exhaust throttle valve 28 is an exhaust pressure sensor (an exhaust pressure detecting means) 30 for determining the exhaust gas pressure in the exhaust pipe 16 provided.

To get the light oil needed in the DPF 78 Burn down accumulated particulate matter, the oxidation catalyst 76 is also upstream of the exhaust throttle valve 28 a light oil additive valve (an auxiliary delivery agent) 32 for the injection of light oil as an aid in the exhaust pipe 16 provided. This light oil additive valve 32 is of the same type as that used in the first embodiment, and is designed to be opened by energizing a solenoid to inject light oil, and to be closed by stopping the energization of the solenoid to stop the injection of light oil. Therefore, when the light oil pressure is fixed, light oil in the amount becomes into the exhaust pipe 16 delivered, the time of energization of the light oil additive valve 32 equivalent.

The same light oil as that supplied to each cylinder of the engine is passed through a light oil delivery passage 34 to the light oil additive valve 32 delivered. At the light oil delivery passage 34 is a light oil temperature sensor (an auxiliary agent temperature detecting means) 36 to determine the temperature of the light oil, the light oil additive valve 32 is provided.

As with the first embodiment, a variety of sensors including the exhaust pressure sensor 30 , the inlet temperature sensor 80 , the inlet pressure sensor 82 and the outlet pressure sensor 84 to the input of an ECU (a control means) 38 , which is a control device for performing the entire control of the exhaust gas purification device according to the present invention including the control of the engine, connected to collect information needed for a variety of controls. At the exit the ECU 38 is a variety of devices including the fuel injector (not shown) for each cylinder and the light oil supplement valve 32 connected, which devices are controlled based on values of the control variables stored in the ECU 38 be determined.

In the exhaust gas purification device having the above-described structure, exhaust gas discharged from the engine is exhausted through the exhaust pipe 16 in the exhaust aftertreatment device 74 introduced, and when the exhaust gas through the DPF 78 flows, particulate matter, which is contained in the exhaust gas, in the DPF 78 caught and accumulated. When a difference between a value by the inlet pressure sensor 82 is determined, and a value by the outlet pressure sensor 84 is determined, etc., it is determined that the amount of particulate matter present in the DPF 78 has accumulated to a predetermined degree, light oil is used as an aid to the light oil additive valve 32 in the exhaust pipe 16 injected. Due to the heat of the exhaust gas, the injected light oil decomposes into HC, the oxidation catalyst 76 is supplied, and is by the oxidation catalyst 76 promoted an oxidation reaction of the HC, so that the HC burns. This combustion of the HC brings the exhaust gas, which is the DPF 78 enters, at a temperature that is suitable for the fine dust, which is in the DPF 78 has burned down (for example, 500 ° C). Consequently, the particulate matter that accumulates in the DPF 78 has accumulated, so that the fine dust removal function that has decreased, is restored and the exhaust gas purification function of the DPF 78 is preserved.

Next, referring to 14 the control of the light oil supply from the light oil additive valve 32 to be discribed. 14 shows the design of control blocks to carry out the control of the light oil supply, which in the ECU 38 are set up.

As in 14 shown includes the ECU 38 a standard delivery quantity determination section 86 to determine the standard delivery amount of light oil needed to remove particulate matter by the DPF 78 was caught burning and thereby the DPF 78 to regenerate; a destination delivery quantity determination section 88 to correct by the standard delivery quantity determination section 86 determined standard delivery quantity Mb based on the exhaust pressure Pex, by the exhaust pressure sensor 30 and the light oil temperature Tf detected by the light oil temperature sensor 62 it is determined to determine the target delivery quantity Mt; and a delivery control section 90 to the light oil additive valve 32 so as to control that light oil in the target delivery amount Mt passing through the target delivery quantity determination section 88 was determined in the exhaust pipe 16 is delivered.

Specifically, the exhaust pressure Pin on the inlet side of the DPF 82 by the inlet pressure sensor 82 is detected, the exhaust pressure Pout on the outlet side of the DPF 78 passing through the outlet pressure sensor 84 is determined, and the exhaust gas temperature Tin at the inlet side of the DPF 78 passing through the inlet temperature sensor 80 is determined to the standard delivery quantity determination section 86 guided. The standard delivery quantity determination section 86 The default delivery quantity Mb of light oil needed to determine the temperature of the exhaust gas that is the DPF 78 enters to increase to burn off particulate matter based on the amount of accumulated particulate matter estimated from a difference between the exhaust pressure Pin and the exhaust pressure Pout and the exhaust temperature Tin from a map stored in advance.

The Way of determining the standard delivery quantity Mb is not on it limited. There are a variety of known techniques that are used can.

As in the first embodiment, the correction is made by the standard delivery quantity determination section 86 certain standard delivery quantity Mb and the control of light oil injection from light oil additive valve 32 is executed according to a flowchart that the same steps as step S12 to S22 of the flowchart of 3 includes.

Specifically, the standard delivery quantity Mb that is determined by the standard delivery quantity determination section 86 has been determined to the target delivery quantity determination section 88 Posted. The exhaust gas pressure Pex flowing through the exhaust pressure sensor 30 is determined, and the light oil temperature Tf, by the light oil temperature sensor 36 is determined become the target delivery quantity determination section 88 and the destination delivery quantity determination section 88 corrects the default delivery amount Mb based on the exhaust pressure Pex and the light oil temperature Tf.

The correction of the standard delivery amount Mb is performed in the same manner as in the first embodiment. In conjunction with the exhaust pressure Pex, a correction factor Rp corresponding to the detected exhaust pressure Pex is determined from a map stored in advance (step S12 in FIG 3 ), where the plan is created so that the correction factor Rp as in 4 shown decreases with the increase of the exhaust pressure Pex. The target delivery quantity determination section 88 corrects the standard delivery quantity Mb by dividing the standard delivery quantity Mb by the correction factor Rp to obtain a pressure corrected delivery amount Mp (step S14 in FIG 3 ).

By the correction of the standard delivery quantity Mb using the correction factor Rp in this way, the pressure-corrected delivery quantity Mp is greater than the default delivery amount Mb when the exhaust pressure Pex is higher than the exhaust pressure value is in the standard state. Therefore, a shortfall of the Delivered quantity compensated due to an increase in the exhaust pressure Pex. Conversely, the pressure-corrected delivery quantity Mp is smaller than the Default delivery quantity Mb, if the exhaust pressure Pex lower than the Exhaust pressure value is in the standard state. Therefore, a surplus in the delivery quantity due to a decrease in the exhaust pressure Pex prevented.

In conjunction with the light oil temperature Tf, a correction factor Rt corresponding to the detected light oil temperature Tf is determined from a map stored in advance (step S16 in FIG 3 ), where the plan is made so that the correction factor Rt is as in 5 shown increases as the light oil temperature increases. The target delivery quantity determination section 88 corrects the pressure-corrected delivery amount Mp by dividing the pressure-corrected delivery amount Mp by the correction factor Rt to obtain the target delivery amount Mt (step S18 in FIG 3 ).

Here the correction is made using the correction factor Rt at the pressure-corrected delivery quantity Mp made. But because the pressure corrected Delivery quantity Mp as mentioned in relation to the first embodiment the correction of the standard delivery quantity Mb based on the exhaust pressure Pex results, the correction is made using the correction factor Rt actually made on the standard delivery quantity Mb. Accordingly, by a Correction of the pressure-corrected delivery quantity Mp, or actually the standard delivery quantity Mb, using the correction factor Mt in this way the target delivery Mt less if the light oil temperature Tf increases. This will be a surplus in the delivery amount due to an increase in light oil temperature Tf avoided. Conversely, the target delivery quantity Mt becomes larger when the light oil temperature Tf decreases. This will cause the shortage of delivery quantity due offset a drop in light oil temperature.

In the flowchart of 3 As mentioned above, first, at step S12 and S14, the pressure corrected delivery amount Mp is obtained by correcting the standard delivery amount Mb based on the exhaust pressure Pex, and then at step S16 and S18, the target delivery amount Mt is determined by the pressure corrected delivery amount Mp based on the light oil temperature is corrected. It should be noted, however, that the order of the steps as in the first embodiment is not limited to this order.

alternative is such an embodiment possible, first, the correction factor Rp corresponding to the exhaust gas pressure Pex and the correction factor Rt, which corresponds to the light oil temperature Tf, from the respective plans be determined, and then the target delivery amount Mt is obtained, by changing the default delivery quantity Mb successively through the correction factors Rp and Rt is shared.

Even though the correction in the case described above by dividing the standard delivery quantity Mb, the pressure-corrected delivery quantity Mp or the temperature-corrected Delivery quantity by the correction factor Rp or the correction factor Furthermore, such an embodiment is possible that one out in advance stored plan the reciprocal of each correction factor will, so the correction by multiplying the delivery quantity is made with the reciprocal.

After the target delivery amount Mt of light oil, which is needed to remove the particulate matter that accumulates in the DPF 78 accumulated to remove by burning has been determined in this way determines the delivery control section 90 from a plan stored in advance, the valve opening time of the light oil additive valve 32 which is necessary for the light oil additive valve 32 Injecting light oil in the target delivery amount Mt (step S20 in FIG 3 ). As the control of the light oil additive valve 32 As in the first embodiment, it is performed in control cycles of a predetermined duration, the schedule is made to match the valve opening time of the light oil supplement valve 32 that corresponds to the target delivery quantity Mt, as in 6 indicated in the form of a duty cycle Dt with respect to the maximum valve opening time in a control cycle.

After the determination of the duty cycle Dt corresponding to the target delivery amount Mt from the schedule, the delivery control section drives 90 the light oil additive valve 32 such that it opens according to the determined duty cycle Dt (step S22 in FIG 3 ), so that light oil in an amount equal to the target delivery amount Mt, from the light oil additive valve 32 in the exhaust pipe 16 is injected. Due to the heat of the exhaust gas decomposes in this way in the exhaust pipe 16 injected light oil to HC and is on the oxidation catalyst 76 promoted an oxidation reaction of the HC, so that the HC burns to increase the exhaust gas temperature. The exhaust gas whose temperature has been raised by the combustion of the HC flows through the DPF 78 , thereby reducing the particulate matter present in the DPF 78 has accumulated, is burned, so that the fine dust capture capacity of the DPF 78 is restored.

It should be noted that the exhaust pressure sensor 30 upstream of the exhaust throttle valve 28 is arranged. This makes light oil even when the pressure in the exhaust pipe 16 by opening and closing the exhaust throttle valve 28 fluctuates, despite changes in the pressure in the exhaust pipe 16 Always delivered properly in the amount needed to remove the particulate matter that builds up in the DPF 78 has accumulated, since the standard delivery amount Mb as mentioned above based on the exhaust pressure Pex, by this exhaust pressure sensor 30 is determined, is corrected.

As described above, in the exhaust gas purification apparatus according to the fourth embodiment of the present invention, the amount of supply of light oil needed to increase the exhaust gas temperature is reduced to the particulate matter present in the DPF 78 has burned off, thereby eliminating the fine dust capture capacity of the DPF 78 to be properly controlled without being affected by changes in exhaust pressure and light oil temperature. As a result, the exhaust gas purification function can be stably maintained and the discharge of excess light oil into the atmosphere can be prevented.

Although the target delivery amount Mt in the above-described exhaust gas purification device according to the fourth embodiment is a correction of the standard delivery amount Mb of the light oil required to the fine dust trapping capacity of the DPF 78 is determined based on both the exhaust gas pressure Pex and the light oil temperature Tf, it should be noted that the correction can be made based on one of them. In this case, the control accuracy is lower compared to the making of the correction based on both the exhaust gas pressure Pex and the light oil temperature Tf, but higher compared to the conventional exhaust gas purification device that takes neither the exhaust pressure nor the light oil temperature into consideration.

Even though Further, the above-described first embodiment of the present invention Invention is an exhaust gas purification device that is based on a diesel engine is applied, it is not limited to the diesel engine, but applicable to any type of engine designed to Particulate matter can be removed from exhaust gas by a DPF.

in the Above were embodiments of the present invention. The present invention however, is not limited to the above-described embodiments. If it is applied to any emission control device, which is designed to be an aid to the preservation of the exhaust gas cleaning function an exhaust gas purifying agent upstream of the exhaust gas purifying agent into an exhaust passage, the present invention may be similar generate positive effects.

Summary

An auxiliary delivery agent ( 32 . 58 ) is provided upstream of an exhaust gas purifying agent ( 24 . 56 . 78 ) an aid for the preservation of the exhaust gas purification function of the exhaust gas cleaning agent ( 24 . 56 . 78 ) to deliver. A control means ( 38 ) for controlling the auxiliary delivery means ( 32 . 58 ), thereby to regulate the amount of the supplied resource, includes a standard supply amount determination section (FIG. 40 . 50 . 68 . 86 ) to determine the standard delivery amount of the resource required to maintain the exhaust gas purification function, a target delivery amount determination section (FIG. 42 . 52 . 70 . 88 ) to determine the target delivery amount of the resource by correcting the default delivery amount based on the exhaust pressure, and a delivery control section ( 44 . 54 . 72 . 90 ) to control the auxiliary delivery means to deliver the aid in the target delivery quantity.

Claims (13)

Exhaust gas purification device for an internal combustion engine, full: an exhaust gas cleaning agent that is in an exhaust passage of the internal combustion engine is provided to exhaust, that of the internal combustion engine pushed out is going to clean, a tool delivery to Auxiliary for preserving the exhaust gas purification function of the exhaust gas cleaning agent upstream to deliver the exhaust gas cleaner into the exhaust passage, one Change factor parameter detection means, by the value of a change factor parameter, the changes caused in the amount of supplied aid to determine and a control means for controlling the auxiliary supply means and thereby the amount of auxiliary agent entering the exhaust passage is delivered, regulate, wherein the control means comprises includes: a standard delivery quantity determination section the standard delivery quantity of the aid required to preserve the Emission control function of the exhaust gas cleaning agent is needed, to determine; a destination delivery amount determination section to a correction of the standard delivery quantity by the standard delivery quantity determination section was determined based on the value of the parameter by the Change factor parameter detection means it has been determined to determine the target delivery quantity of the auxiliary; and a delivery control section to the auxiliary delivery means to steer to the aid with the target delivery quantity, which by the destination delivery quantity determination section has been determined to deliver includes. Emission control device for an internal combustion engine according to Claim 1, wherein the change factor parameter detecting means an exhaust pressure detecting means includes the exhaust pressure in the exhaust passage upstream determine the exhaust gas cleaning agent, and the change factor parameter the exhaust pressure is. Emission control device for an internal combustion engine according to Claim 2, wherein designed the auxiliary delivery means to is, the tool by opening and closing to deliver a solenoid valve and to stop its delivery, and of the Delivery control section a working cycle control of opening and closing the solenoid valve performs, around the aid in the target delivery quantity into the exhaust gas passage to deliver. Emission control device for an internal combustion engine according to Claim 3, wherein the delivery control section the duty cycle control of opening and closing the solenoid valve performs so that the work cycle gets bigger, when the exhaust pressure increases. Emission control device for an internal combustion engine according to Claim 4, wherein the variation factor parameter detection means an auxiliary means temperature detecting means includes the temperature of the resource, and the change factor parameter Aid temperature is. Emission control device for an internal combustion engine according to Claim 5, wherein the change factor parameter detecting means Further, an exhaust pressure detecting means includes the exhaust pressure in the exhaust passage upstream of the exhaust gas purifier, and the target supply amount determining section the target delivery quantity by correcting the standard delivery quantity Basis of the exhaust pressure determined by the exhaust pressure detecting means and the auxiliary agent temperature detected by the auxiliary agent temperature detecting means is determined. Emission control device for an internal combustion engine according to Claim 5 or 6, wherein the auxiliary delivery agent thereto is designed to open the tool by opening and closing a To supply solenoid valve and adjust its delivery, and of the Delivery control section a working cycle control of opening and closing the solenoid valve performs, around the aid in the target delivery quantity into the exhaust gas passage to deliver. Emission control device for an internal combustion engine according to Claim 7, wherein the delivery control section the duty cycle control of opening and closing the solenoid valve performs so that a work cycle for the duty cycle control becomes smaller as the auxiliary agent temperature increases. Emission control device for an internal combustion engine according to one of the claims 2 to 8, wherein the exhaust gas purifying agent is a NOx adsorption catalyst designed to convert NOx into exhaust gas containing the NOx adsorption catalyst enters to adsorb when the air-fuel ratio of the exhaust gas is lean, and release and reduce the adsorbed NOx when the Air-fuel ratio of the Exhaust gas is fat, the auxiliary delivery means fuel as an aid upstream of the NOx adsorption catalyst into the exhaust passage, and the Standard delivery quantity determination means the standard delivery quantity of Fuel determined that needed is to cause the NOx adsorption catalyst NOx, which has been adsorbed by the NOx adsorption catalyst releases and reduced. Emission control device for an internal combustion engine according to one of the claims 2 to 8, wherein the exhaust gas purifying agent is a NOx adsorption catalyst designed to convert NOx into exhaust gas containing the NOx adsorption catalyst enters to adsorb when the air-fuel ratio of the Exhaust gas is lean, and to release and reduce the adsorbed NOx when the air-fuel ratio of the Exhaust gas is fat, the auxiliary delivery means fuel as an aid upstream of the NOx adsorption catalyst into the exhaust passage, and the Standard delivery quantity determination means the standard delivery quantity of Fuel determined that needed to increase the NOx adsorption capacity of the NOx adsorption catalyst, by the sulfur component passing through the NOx adsorption catalyst was adsorbed from the exhaust, decreased, restore, by causing the NOx adsorption catalyst to adsorb Sulfur component releases. The exhaust gas purification device for an internal combustion engine according to any one of claims 2 to 8, wherein the exhaust gas purifying means is a NOx catalyst configured to selectively reduce NOx in the exhaust gas, the auxiliary supply means supplies urea water as an auxiliary upstream of the NOx catalyst into the exhaust passage, and Standard delivery quantity determination means the standard delivery quantity of urea water be that is needed for the NOx catalyst to selectively reduce NOx in the exhaust gas. Emission control device for an internal combustion engine according to one of the claims 2 to 8, wherein the exhaust gas cleaner a particulate filter which is designed to catch particulate matter in the exhaust gas, the Auxiliary delivery agent uses fuel as an aid upstream of the Particulate filter provides in the exhaust passage, and the standard delivery quantity determination means determines the standard delivery quantity of fuel needed around the particulate filter by burning off particulate matter passing through the Particle filter has been caught to regenerate. Exhaust gas purification device according to one of claims 2 to 4 and 6, further comprising an exhaust throttle, in the exhaust passage is arranged to regulate the exhaust gas flow rate in the exhaust passage, in which the exhaust pressure detecting means the exhaust pressure in the exhaust passage upstream the exhaust throttle determines, and the auxiliary delivery agent upstream the exhaust throttle is arranged.