JP2003056335A - Exhaust purification catalyst device for internal combustion engine - Google Patents

Abstract

(57) [PROBLEMS] An exhaust purification catalyst that reliably removes a purification performance reducing substance without deteriorating the operation state of an internal combustion engine even if a purification performance reduction substance other than nitrogen oxides (NOx) adheres. Provided is an exhaust purification catalyst device capable of maintaining the function of (NOx catalyst). SOLUTION: Attachment amount estimating means (S10) for estimating the attachment amount of the purification performance reducing substance attached to the exhaust gas purification catalyst, and when the attachment amount estimated by the attachment amount estimation means reaches a predetermined attachment amount (S12). Catalyst temperature raising means for performing temperature control of the combustion gas in the internal combustion engine to raise the temperature of the exhaust purification catalyst, and the catalyst temperature raising means sets the ignition timing of the internal combustion engine to the engine speed of the internal combustion engine and the engine speed. An ignition timing correcting means (S24) for correcting the retard amount to the retard side by a retard amount set based on the engine load is included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification catalyst device for an internal combustion engine, and more particularly to a device having a purification efficiency restoring function.

[0002]

Related Background Art When the internal combustion engine is in a predetermined operating state, the air-fuel ratio is controlled to a target value (for example, 22) on the fuel lean side (lean side) with respect to the stoichiometric air-fuel ratio (14.7),
An air-fuel ratio control method for improving the fuel consumption characteristics of an engine is known. In such a lean air-fuel ratio control method,
In the conventional three-way catalytic converter, nitrogen oxides (NO
There is a problem that x) cannot be sufficiently purified.

In order to solve this problem, NOx in exhaust gas is adsorbed in an oxygen rich state (oxidizing atmosphere),
An exhaust gas purification catalyst having a characteristic of reducing the adsorbed NOx in a hydrocarbon (HC) excess state (reducing atmosphere), so-called NO.
It is known to use x-catalysts to reduce NOx emissions to the atmosphere. With this NOx catalyst, NOx is adsorbed during lean air-fuel ratio control. However, if the lean combustion operation is continuously performed, the amount of adsorption of the catalyst is limited. Most of the NOx will be emitted to the atmosphere. Therefore, NOx
A method of switching the air-fuel ratio to a rich air-fuel ratio control for controlling the air-fuel ratio to a stoichiometric air-fuel ratio or a value close to the stoichiometric air-fuel ratio before the amount of adsorption of the catalyst reaches saturation and performing NOx reduction in a reducing atmosphere (rich state) is disclosed in Japanese Patent Application Laid-Open No. HEI 06-242242. It is known from Japanese Patent Laid-Open No. 5-133260.

However, the substances adsorbed on the NOx catalyst are
Only NOx is required, but substances other than NOx, such as sulfur and its compounds, actually adhere. NO like this
Substances other than x (hereinafter, referred to as purifying ability lowering substances) adhere to the place where NOx should be originally adsorbed instead of NOx, so that the adsorbing ability of NOx is reduced. Such substances other than NOx that reduce the purifying ability cannot be removed even by performing the air-fuel ratio control as disclosed in the above publication, and the deposited amount thereof will increase with the passage of time. Then, if the deposition of the purifying ability lowering substance is left as it is, the NOx adsorbing ability will only be lowered, and the NOx catalyst may not fully perform its function.

Therefore, there is a technique for retarding the ignition timing to control the exhaust temperature to a temperature at which the substance having reduced purification ability does not adhere, or for enriching the air-fuel ratio at high exhaust temperature to remove the substance having reduced purification capability. It is disclosed in Japanese Patent No. 88518.

[0006]

However, in the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 6-88518, the substance having a reduced purification capacity is directly released into the atmosphere, or
Unless the exhaust gas temperature becomes high, the purification capacity-reducing substance is not removed, so that the NOx catalyst may not fully perform its function, which is not preferable.

Further, if the ignition timing and the air-fuel ratio are controlled, the operating condition of the internal combustion engine may deteriorate. The present invention has been made to solve such a problem, and an object thereof is to deteriorate the operating state of an internal combustion engine even if a substance having a purifying ability other than nitrogen oxide (NOx) is attached. An object of the present invention is to provide an exhaust gas purification catalyst device capable of reliably removing a substance having a reduced purification capacity without performing the purification and maintaining the function of an exhaust gas purification catalyst (NOx catalyst).

[0008]

In order to achieve the above object, in the invention of claim 1, the exhaust gas is arranged in the exhaust passage of the internal combustion engine and adsorbs nitrogen oxides in the exhaust gas during lean combustion operation. In an exhaust gas purification catalyst device for an internal combustion engine provided with a purification catalyst, an adhesion amount estimation means for estimating an adhesion amount of a purification performance lowering substance adhered to the exhaust purification catalyst,
Catalyst adhering means for increasing the temperature of the exhaust purification catalyst by controlling the temperature of the combustion gas in the internal combustion engine when the adhering amount estimated by the adhering amount estimating means reaches a predetermined adhering amount. The catalyst temperature increasing means includes an ignition timing correcting means for correcting the ignition timing of the internal combustion engine to a retard side by a retard amount set based on an engine rotation speed and an engine load of the internal combustion engine. It is characterized by becoming.

As a result, the adhering amount of the purifying ability-decreasing substance which adsorbs on the exhaust purifying catalyst and deteriorates the purifying ability of nitrogen oxides is well estimated, and when the adhering amount exceeds the predetermined adhering amount, the ignition of the internal combustion engine is ignited. The timing is corrected to the retard side, and the temperature of the exhaust purification catalyst rises due to the heat of the combustion gas that rises in temperature, and the substances with reduced purification ability are burned and removed satisfactorily from the exhaust purification catalyst. The ability to adsorb substances will be restored, but at this time, the ignition timing retard amount is set appropriately according to the engine speed and the engine load, so the engine operating condition deteriorates when the ignition timing is retarded. Is preferably prevented.

According to a second aspect of the present invention, in the first aspect, the catalyst temperature raising means increases the intake air amount to the internal combustion engine when the ignition timing is retarded. The intake air amount correction means sets the increase correction amount of the intake air based on the engine speed and the engine load of the internal combustion engine.

As a result, since the intake air amount is appropriately supplemented by the increase in the intake air amount, it is possible to suitably prevent the engine output from being lowered when the ignition timing is retarded. Further, according to the invention of claim 3, in an exhaust gas purification catalyst device for an internal combustion engine, which is provided in an exhaust passage of an internal combustion engine and includes an exhaust gas purification catalyst that adsorbs nitrogen oxides in exhaust gas during lean combustion operation, Adhesion amount estimating means for estimating the adhesion amount of the purification capacity lowering substance adhering to the purification catalyst, and when the adhesion amount estimated by the adhesion amount estimating means reaches a predetermined adhesion amount, combustion gas in the internal combustion engine A catalyst temperature raising means for performing temperature control to raise the temperature of the exhaust purification catalyst, wherein the catalyst temperature raising means includes an ignition timing correction means for correcting the ignition timing of the internal combustion engine to a retard side, Intake air amount correction means for increasing the intake air amount to the internal combustion engine when the ignition timing is retarded, and the intake air amount correction means includes an engine rotation speed and an engine load. Based on is characterized by setting the increase correction amount of the intake air.

As a result, the amount of adhering substances that are adsorbed by the exhaust purification catalyst and reduce the purifying ability of nitrogen oxides is estimated to be good. If the adhering amount exceeds a predetermined amount, the ignition of the internal combustion engine is ignited. The timing is corrected to the retard side, and the temperature of the exhaust purification catalyst rises due to the heat of the combustion gas that rises in temperature, and the substances with reduced purification ability are burned and removed satisfactorily from the exhaust purification catalyst. The adsorption capability of the object is restored, but at this time, the intake air amount is appropriately compensated by the increase of the intake air amount, so that the reduction of the engine output at the time of retarding the ignition timing is preferably prevented.

According to a fourth aspect of the present invention, in the third aspect, the ignition timing correction means sets the retard amount of the ignition timing based on the engine rotation speed and the engine load of the internal combustion engine. I am trying. This allows
Since the retard amount of the ignition timing is appropriately set according to the engine rotation speed and the engine load, the deterioration of the engine operating state at the time of retarding the ignition timing is preferably prevented.

Further, in the invention of claim 5, in claim 1 or 3, the catalyst temperature raising means sets the air-fuel ratio to a rich value including a stoichiometric air-fuel ratio when the temperature of the exhaust purification catalyst reaches a predetermined temperature. It is characterized by further including switching means for switching to rich combustion operation with a side air-fuel ratio. Thereby, after the exhaust purification catalyst is heated by the temperature control of the combustion gas in the internal combustion engine, when the catalyst temperature reaches a predetermined temperature rising temperature, rich combustion operation is performed,
Exhaust gas contains a large amount of unburned hydrocarbons. Then, the unburned hydrocarbons and the purifying ability reducing substance react with each other at a high temperature, and the purifying ability reducing substance is satisfactorily removed from the exhaust purification catalyst.

The invention of claim 6 is characterized in that, in claim 5, the rich side air-fuel ratio is set on the basis of an engine speed and an engine load.
As a result, the air-fuel ratio for removing the purifying ability lowering substance is appropriately set according to the engine rotation speed and the engine load, and the purifying ability lowering substance is reliably removed.

Further, in the invention of claim 7, in claim 2 or 3, at least one of the intake air amount correction means and the ignition timing correction means changes from a control target value before correction to a control target value after correction. Is characterized by gradually switching. Further, in the invention of claim 8, in claim 2 or 3, the intake air amount correction means and the ignition timing correction means gradually switch from a control target value before correction to a control target value after correction. It is characterized by that.

The invention according to claim 9 is characterized in that, in claim 1 or 3, the ignition timing correction means gradually switches from the ignition timing before correction to the ignition timing after correction. Further, in the invention of claim 10, in claim 5, the correction to the rich side air-fuel ratio is performed by gradually switching from the air-fuel ratio before correction to the air-fuel ratio after correction.

As a result, it is possible to suitably prevent the operating state of the engine body from fluctuating due to the rapid correction.
Deterioration of driving feeling is prevented. In addition, claim 1
According to a first aspect of the present invention, in the first or third aspect, the catalyst temperature raising means is operated such that the operating state of the internal combustion engine is within a predetermined engine rotation speed range and a predetermined load range.

As a result, the catalyst temperature is satisfactorily carried out in a stable operating state.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. First, the first embodiment will be described. FIG. 1 is a schematic configuration diagram showing an internal combustion engine equipped with an exhaust purification catalyst device according to the present invention.

In the figure, reference numeral 1 is an automobile engine, for example, a V-type 6-cylinder gasoline engine body,
The combustion system as well as the intake system and ignition system are designed to allow lean combustion. In this V-type 6-cylinder gasoline engine body (hereinafter, simply referred to as an engine body) 1, three cylinders are arranged in each of the one side (left side) bank 1a and the other side (right side) bank 1b. An air flow for detecting an air cleaner 5 and an intake air amount Af via an intake manifold 4 having fuel injection valves 3a, 3b attached to intake ports 2a, 2b provided for each cylinder of the left bank 1a and the right bank 1b. Sensor 6, throttle valve 7, IS
An intake pipe 9 having a C (idle speed control) valve 8 and the like is connected.

As the air flow sensor 6, a Karman vortex type air flow sensor or the like is preferably used. The ISC valve 8 is for controlling the idling rotation speed, and adjusts the valve opening according to the fluctuation of the engine load Le due to the operation of an air conditioner (not shown), etc. to change the intake air amount and stabilize the idling operation. It has a function of causing it. Further, the ISC valve 8 is actuated to the valve opening side during the ignition timing correction control and the air-fuel ratio correction control, which will be described later, and acts to compensate for the decrease in the engine output.

The exhaust ports 10a and 10b of each cylinder are also provided.
An exhaust pipe 14 to which an air-fuel ratio sensor (linear O ₂ sensor or the like) 12 for detecting the air-fuel ratio is attached is connected to the exhaust manifold 11a, 11b. A muffler (not shown) is connected via the catalyst 13. A secondary air introduction pipe 30 extending from the air cleaner 5 is connected to the exhaust pipe 14, and the secondary air is introduced into the exhaust pipe 1 through the secondary air introduction pipe 30.
An air pump 32 for supplying air to the fuel cell 4 is interposed.
Thereby, air can be supplied to the exhaust pipe 14 as needed. The output of the air pump 32 can be adjusted by changing the current value or the like.

The exhaust purification catalyst 13 comprises two catalysts, a NOx catalyst 13a and a three-way catalyst 13b, and the NOx catalyst 13a is arranged upstream of the three-way catalyst 13b. The NOx catalyst 13a is NO in the oxidizing atmosphere.
It has a function of adsorbing x (nitrogen oxide) and reducing NOx to N ₂ (nitrogen) in a reducing atmosphere in which HC (hydrocarbon) is present. As the NOx catalyst 13a, for example, a catalyst composed of Pt having a heat deterioration resistance and an alkaline rare earth such as lanthanum or cerium is used. A catalyst temperature sensor (catalyst temperature detection means) 26 is connected to the NOx catalyst 13a so that the temperature of the NOx catalyst 13a can be detected up to a high temperature range.

On the other hand, the three-way catalyst 13b has a function of oxidizing HC and CO (carbon monoxide) and reducing NOx, and the reduction of NOx by the three-way catalyst 13b reduces the theoretical air-fuel ratio (14.7). ) It is designed to be maximally promoted during combustion in the vicinity. In the engine body 1, spark plugs 16a and 16b for igniting a mixed gas of air and fuel supplied from the intake ports 2a and 2b to the combustion chambers 15a and 15b are arranged for each cylinder.
Further, reference numeral 18 is a crank angle sensor that detects a crank angle synchronization signal θCR from an encoder that operates in conjunction with a camshaft, reference numeral 19 is a throttle sensor that detects the opening degree θTH of the throttle valve 7, and reference numeral 20 is a cooling water temperature TW. A water temperature sensor, reference numeral 21 is an atmospheric pressure sensor that detects the atmospheric pressure Pa, and reference numeral 22 is an intake air temperature sensor that detects the intake air temperature Ta.

The engine rotational speed Ne is calculated from the time interval at which the crank angle synchronization signal θCR detected by the crank angle sensor 18 is generated. The volume efficiency ηv is calculated from the air flow rate Af detected by the air flow sensor 6 and the engine rotation speed Ne, and the atmospheric pressure Pa detected by the atmospheric pressure sensor 21 and the intake air temperature detected by the intake air temperature sensor 22. It is corrected by Ta or the like. Further, the engine load Le is calculated from the throttle opening θTH detected by the throttle sensor 19, the volume efficiency ηv, and the like.

In the passenger compartment, an input / output device (not shown) and a storage device (ROM, RA
M, non-volatile RAM, etc.), a central processing unit (CPU), an ECU equipped with a timer counter or the like functioning as a time measuring means
An (electronic control unit) 23 is installed to perform air-fuel ratio control of the engine body 1, ignition timing control, intake air amount control, refresh control of an exhaust purification catalyst device described later, and the like. On the input side of the ECU 23, a distance meter 25 for counting the traveling distance of the vehicle by the integrated value of vehicle speed pulses and the like.
The various sensors described above are connected, and the detection information from these sensors is input. On the other hand, on the output side, the above-mentioned fuel injection valves 3a, 3b, the ignition unit 24, etc. are connected, and the optimum value calculated based on the input information from various sensors is output to them. ing.
The fuel injection valves 3a and 3b are driven by a pulsed current supplied by a command from the ECU 23.
The fuel injection amount is determined by the pulse width of the current.
The ignition unit 24 outputs a high voltage to the ignition plugs 16a and 16b of each cylinder according to a command from the ECU 23.

Next, the operation of the exhaust gas purification catalyst device configured as described above will be described. The flowcharts shown in FIGS. 2 and 3 show the refresh control procedure executed by the ECU 23. This refresh control is NO
When it is determined that the deposits (substances for reducing the purifying ability) other than NOx attached to the x-catalyst 13a, such as sulfur and its compounds, have reached a predetermined amount, the NOx catalyst 13a is controlled by the temperature control of the combustion gas of the engine body 1. Perform a refresh operation to raise the temperature to a high temperature and remove the substances with reduced purification capacity from N
The Ox is to be removed so as not to become an obstacle when adsorbing to the NOx catalyst 13a.

First, in step S10, the ECU 23
Indicates that the amount of adherence of the purification capacity lowering substance increases substantially in proportion to the travel distance D of the vehicle. Therefore, the travel distance D of the vehicle is read by the distance meter 25, and the purification capacity deterioration adhered and deposited on the NOx catalyst 13a is reduced. Estimate the amount of substance (adhesion amount estimation means). Next, in step S12, the travel distance D read in step S10 is used to determine whether or not the purification capacity-reducing substance has reached a predetermined amount, which is a predetermined value D1 (for example, 1000 km).
It is determined whether or not the above. This predetermined value D1 is set to an appropriate value through experiments, etc., and is within a range in which the amount of adhering purification capacity-reducing substances does not exceed the permissible amount, that is, the NOx emission amount that increases due to the adhesion of purification capacity-reducing substances is a regulated value such as laws and regulations. It is set to a value within the range not exceeding. The determination result is Yes
In the case of (affirmative), it can be determined that the substance having a reduced purification capacity has exceeded the predetermined amount, and the process proceeds to step S16. On the other hand, if the determination result is No (no), the travel distance D is the predetermined value D1 (100
If it has not reached 0 km), next step S14
Proceed to.

Step S14 is a step of determining whether or not the battery, which is the control power source, has just been removed and then reconnected for maintenance of the vehicle or the like. This determination is made by the RAM of the ECU 23 when the battery is removed.
The estimated value of the adhered amount of the purification ability lowering substance estimated based on the traveling distance D stored in is once reset to zero value,
This is carried out to prevent the estimated value of the adhered amount and the actual adhered amount from becoming inconsistent.

If the determination result in step S14 is No (negative), the battery is connected, but the determination result of the traveling distance D in step S12 is still the predetermined value D1.
It can be determined that the state has not reached (1000 km), and in this case, the routine is terminated without doing anything. On the other hand, if the determination result is Yes (affirmative) and the battery has just been reconnected, the process proceeds to step S16, similarly to the determination result of Yes (affirmative) in step S12. Even if the battery is removed, if the estimated value of the adhered amount based on the traveling distance D is surely stored and held by the backup function of the ECU 23, the determination in step S14 may not be performed. .

In step S16, it is determined whether or not the operating state of the engine body 1 is a state in which the refresh operation may be performed based on the signal values from various sensors. Here, the engine speed Ne, the volumetric efficiency ηv, which is an element of the engine load Le, and the cooling water temperature TW are the objects of judgment, and whether the respective values are within the range of the inequalities shown in (1) to (3) below. Is determined.

Ne1 ≤ Ne ≤ Ne2 (1) ηv1 ≤ ηv ≤ ηv2 (2) TW1 ≤ TW (3) Here, Ne1, Ne2, ηv1, ηv2 and TW1 are threshold values, for example, Ne1 is 1500 rpm. , Ne2 is 5000r
pm and ηv1 are 30%, ηv2 is 85%, and TW1 is set to 50 ° C. at which it can be considered that the warm-up operation is completed, for example. These thresholds indicate values at which the operating state of the engine body 1 changes from a so-called medium load range to a high load range. In this case, the exhaust gas temperature of the engine body 1 is equal to or higher than a predetermined temperature TEX (for example, 600 ° C.). It is estimated that there is.

In this way, the operating condition in which the operating condition of the engine body 1 is changed from the medium load region to the high load region is, for example, Ne1,
This is because if the refresh operation is performed in a low load range smaller than ηv1, the output of the engine body 1 may not be stable, and the driving feeling may deteriorate.
In a high load range where the value of ηv is larger than Ne2 and ηv2, the exhaust gas temperature is high, and the NOx catalyst 13a is also in a high temperature state. Therefore, when the refresh operation is performed in this state, the NOx catalyst is This is because 13a may be overheated and burned.

If the determination result of step S16 is No (negative), that is, if any of Ne, ηv, and TW is out of the above range, it can be determined that the refresh operation should not be performed. Does not perform the refresh operation, and goes through step S18 and then step S1 again.
6 is executed, and the execution of step S16 is repeated until the determination result is no (No). In step S18, a flag f (RF) described later is reset to a zero value.

On the other hand, the determination result of step S16 is Yes.
(Yes), all the values of Ne, ηv, and TW are inequality
In the case of being in the range of (1) to (3), the operating state of the engine body 1 is in the medium load range to the high load range and the refresh operation may be performed. It proceeds to step S20. At this time, the timer counter of the ECU 23 starts integrating the elapsed time t.

In step S20, the flag f (R) for storing that the refresh mode operation described later is executed is stored.
This is a step of determining whether or not F) has a value of 1. Immediately after the determination result of step S16 is Yes (affirmative) and the refresh operation is enabled, this flag f (RF)
Since the value of is a reset zero value state (f (RF) = 0), the determination result of step S20 is inevitably No (negative) in this case, and the process proceeds to step S24.

The subsequent step S24 and subsequent steps are steps for executing the refresh operation. Steps S24 and S26 are steps that constitute the temperature increase mode operation of the refresh operation, and here, the NOx catalyst 13a is used.
Temperature TCAT of the predetermined temperature T1 (eg 65
The temperature is raised to 0 ° C. (catalyst temperature raising means).

First, in step S24, the ignition timing of each cylinder of the engine body 1 is corrected (ignition timing correction means). This ignition timing correction is to retard the ignition timing of all cylinders. By retarding in this manner, combustion is not yet completed and is maintained even when the exhaust valve of each cylinder is opened. Therefore, the engine body 1
The exhaust gas discharged from the exhaust gas flows out to the exhaust pipe 14 while maintaining the burned state, and the exhaust gas temperature in the exhaust pipe 14 becomes high.

The correction amount (retardation amount) of the ignition timing is preset based on the engine speed Ne and the volumetric efficiency ηv, and a map showing the relationship between them is RO of the ECU 23.
It is stored in M. Then, when the ignition timing is corrected, a correction amount according to the engine rotation speed Ne and the volumetric efficiency ηv is read from this map, and an appropriate correction is performed according to this correction amount.

After performing the ignition timing correction as described above,
Then, the process proceeds to step S26. In this step S26,
The ISC valve 8 is adjusted to correct the intake air amount (intake air amount correction means). This correction of the intake air amount is carried out to prevent the combustion efficiency from decreasing and the engine output from decreasing due to the ignition timing being retarded. Here, the ISC valve 8 is opened. To increase the intake air amount. As a result, combustion is performed better, and the engine output is stably maintained constant without lowering.

As in the case of the ignition timing correction, the correction amount of the intake air is the engine rotation speed Ne and the volumetric efficiency η.
A map which is set in advance based on v and shows the relationship between them is stored in the ROM of the ECU 23. Then, when correcting the intake air amount, the correction amount is read from this map, and the intake air is appropriately corrected.
When the correction amount of the intake air is large and the correction cannot be sufficiently performed only by adjusting the ISC valve 8,
Separate intake pipe 9 so as to avoid the throttle valve 7.
It is also possible to provide a bypass pipe (not shown) in the above and operate an air bypass valve interposed in this bypass pipe to increase the intake air amount.

When the temperature increasing mode operation of the refresh operation is performed as described above, the NOx catalyst 13a is rapidly heated, and the temperature TCAT of the NOx catalyst 13a is N.
Thus, the predetermined temperature T1 (650 ° C.), which is sufficient to burn and remove the substance with reduced purification ability attached to the Ox catalyst 13a, is reached. In the next step S30, the catalyst temperature TCAT detected by the catalyst temperature sensor 26 is the predetermined temperature T1.
(For example, 650 ° C.) or more is determined.
The determination result is No (negative) and the catalyst temperature TCAT is the predetermined temperature T1.
If the temperature is lower than (650 ° C.), it can be determined that the temperature is not sufficient to burn and remove the substance with reduced purification capacity, and the process returns to step S16 described above and waits until the operating state of the engine body 1 stabilizes. On the other hand, if the determination result is Yes (affirmative) and it is determined that the catalyst temperature TCAT has reached the predetermined temperature T1 (650 ° C.), the process proceeds to step S32.

In step S32, the above-mentioned step S
The determination result of 16 is Yes (affirmative), and it is determined whether or not the elapsed time t when the clocking is started with the execution of the refresh operation has passed a fixed time ts (for example, 5 seconds). If the determination result is No (negative) and the predetermined time ts (5 seconds) has not yet passed, it can be considered that the operating state of the engine body 1 is unstable, and in this case, the process returns to step S16. , Wait for the operating condition of the engine body 1 to stabilize. On the other hand, if the determination result is Yes (affirmative), the fixed time t
When it is determined that s (5 seconds) has elapsed, it can be considered that the operating state of the engine body 1 is stable, and then the process proceeds to step S34.

Steps S34 to S38 are steps constituting the refresh mode operation of the refresh operation. Here, the temperature of the NOx catalyst 13a which has reached the predetermined temperature T1 (650 ° C.) is set to the predetermined temperature T1 (6
The NOx catalyst 13a is maintained at 50 ° C.) so that the substance having reduced purification ability (sulfur or its compound) is almost completely burned and removed from the NOx catalyst 13a.

In this refresh mode operation, first, in step S34, the air-fuel ratio is corrected (switching means). In this air-fuel ratio correction, the air-fuel ratio is corrected to the rich side, and the air-fuel ratio at this time is obtained from the map based on the engine rotation speed Ne and the volume efficiency ηv, and the value is 13.7, for example. By setting the air-fuel ratio to the rich side in this way, the exhaust gas contains more CO and unburned HC than in the temperature rising mode operation. Then, the unburned HC reacts with the purifying ability lowering substance that has been burned and removed at high temperature, whereby the purifying ability lowering substance is surely removed without adhering to the NOx catalyst 13a again. Further, since the unburned HC reduces NOx, the NOx adsorbed on the NOx catalyst 13a is reduced.
Will also be removed at the same time.

In step S36, as in the case of the temperature increasing mode operation, the ignition timing is continuously corrected to the retard side to maintain the exhaust gas temperature at a high temperature, and the temperature TCA of the NOx catalyst 13a is increased.
Maintain T at a predetermined temperature T1 (650 ° C). Then, in step S38, similarly to the case of the temperature increase mode operation, the intake air amount is corrected while the ISC valve 8 is adjusted to the valve opening side to compensate for the decrease in the engine output.
In this refresh mode operation, the NOx catalyst 13
Since it is sufficient to maintain the temperature TCAT of a at the predetermined temperature T1 (650 ° C.), the ignition timing correction amount and the intake air correction amount are set smaller than those in the temperature increasing mode operation, and only the minimum necessary for maintaining the temperature is set. It may be limited to the amount.

By the way, when the ignition timing correction, the intake air amount correction, and the air-fuel ratio correction are performed, if these corrections are performed rapidly, the operating state of the engine body 1 is changed and the driving feeling is deteriorated. Therefore, it is desirable to perform the correction by gradually approaching the correction value. When this refresh mode operation is completed, the process proceeds to step S40, the flag f (RF) is set to the value 1, the execution of the refresh mode operation is stored, and the process proceeds to step S42.

In step S42, the step S42
Each time is executed, the cumulative time CST is calculated by the following equation (8). Here, the catalyst temperature TCAT is the predetermined temperature T1 (65
(0 ° C.) and the elapsed time t, which has started to be measured at the start of the refresh operation, has accumulated for a fixed time ts (5 seconds), and the duration of the refresh operation is integrated. CST = CST + 1 (8) Since the cumulative time CST is incremented by 1 only when the step S42 is executed, the determination result of step S16 described above is No (negative).
In the case of No, or when either of the determination results of step S30 or step S32 is No (negative), it is not added. Therefore, steps S16 and S3
The determination results of 0 and step S32 are all Yes (affirmative), and only the time when the refresh mode operation is reliably executed is accumulated as the net time. The value 1 to be counted up corresponds to, for example, the reference time Xt set according to the execution cycle of the routine.

The cumulative time CST added in this way is the predetermined value XC corresponding to the predetermined time t1 set beforehand by experiments or the like in the next step S44, for example, 600 seconds).
The refresh operation is compared with the predetermined time t1 (600
It is determined whether or not it has been performed for 2 seconds. This predetermined time t1 (600 seconds) is a time at which it can be considered that the purification capacity lowering substance has been sufficiently removed. If the determination result is No (negative) and the cumulative time CST has not reached the predetermined value XC, the purification capacity is It can be determined that the removal of the reduced substance is not sufficient, and the process returns to step S16 and the refresh operation is continued.

If the cumulative time CST has not reached the predetermined value XC and the step S16 is executed again, the result of the determination is Yes (affirmative) and the engine body 1 is in a good operating state for refresh operation. Proceed to S20. This time, since the refresh mode operation has already been executed and the flag f (RF) has been set to the value 1, the determination result of this step S20 becomes Yes (affirmative). In this case, the process proceeds to step S34 without executing the temperature increasing mode operation, and only the refresh mode operation is executed to maintain the catalyst temperature TCAT at the predetermined temperature T1 (650 ° C).

On the other hand, although the refresh operation is once started, the operating state of the engine body 1 is out of the refresh operation range, and the determination result of step S16 is No.
In the case of (negative), the refresh operation is stopped and the process proceeds to step S18. In step S18, the value of the flag f (RF) is reset to zero (f (RF) =
0). Once the value of the flag f (RF) is once returned to the zero value in this way, when the step S20 is executed next time through the step S16, the determination result is No (negative), and the temperature rising mode operation after the step S24. Will be executed again. As a result, the catalyst temperature TCAT lowered due to the suspension of the refresh operation is again set to the predetermined temperature T1 (6
It can be returned to 50 ° C).

When the determination result of step S44 is Yes (affirmative) and it is determined that the cumulative time CST has reached the predetermined value XC, it can be considered that the substance having a reduced purification capacity is almost completely removed, and the refresh is performed. After driving,
Finally, step S46 is executed. In step S46, the accumulated time CST, the traveled distance D, and the value of the flag f (RF) that have been accumulated are reset to zero values due to the end of the refresh operation. This prepares for the next refresh operation.

As described above, in the first embodiment, the temperature control of the combustion gas is performed by the ignition timing correction to raise the temperature of the NOx catalyst 13a to remove the substance having a reduced purification capacity, but the NOx catalyst 13a is raised. The catalyst heating means for heating is not limited to this, and other methods can be applied. The second embodiment will be described below. Example 2
Is a catalyst temperature raising means for raising the temperature of the NOx catalyst 13a, which adopts a method of controlling oxygen addition to the exhaust gas, that is, a method of introducing secondary air into the exhaust gas containing unburned HC.

In the second embodiment, in the exhaust gas purification catalyst device shown in FIG. 1, only the control contents of the temperature rising mode operation and the refresh mode operation in the flow charts shown in FIGS. 2 and 3 are changed to change the NOx catalyst. The refresh control of 13a is performed. Hereinafter, the refresh control in the second embodiment will be described. The steps other than the temperature increase mode operation and the refresh mode operation are as shown in FIGS. 2 and 3, and those steps have been described above, and therefore will not be described here. Is omitted.

First, in the temperature increasing mode operation, as shown in FIG. 4, the air-fuel ratio correction is executed in step S241 (switching means). In this air-fuel ratio correction, the air-fuel ratio of each cylinder is corrected to the rich side similarly to the air-fuel ratio correction (step S34) in the first embodiment described above. The air-fuel ratio at this time is obtained from a map based on the engine rotation speed Ne and the volume efficiency ηv, but the value may be a fixed value. With this correction,
Exhaust gas contains a large amount of unburned HC.

Next, at step S261, the same ignition timing correction as the ignition timing correction (step S24) in the above-described first embodiment is performed to retard the ignition timing of each cylinder. This raises the exhaust gas temperature. Then, in step S281, the air pump 32 described above is operated to supply the secondary air to the exhaust pipe 14 through the secondary air introduction pipe 30. At this time, a large amount of unburned HC is contained in the exhaust pipe 14 due to the above-described air-fuel ratio correction.
Further, since the ignition timing retard correction is performed and the exhaust gas temperature has reached the high temperature range, the unburned HC is burned due to the presence of oxygen in the secondary air, and the exhaust gas temperature in the exhaust pipe 14 further rises. It will be. Then, the temperature TCAT of the NOx catalyst 13a rapidly rises due to the passage of this high-temperature exhaust gas.

The catalyst temperature TCAT is the predetermined temperature T1 (650 ° C.)
Although not shown here, if the determination result of the above-described step S30 and step S32 is Yes (affirmative), the refresh mode operation is performed next. In this refresh mode operation, similarly to the case of the temperature increase mode operation described above, the air-fuel ratio correction is performed in step S341, the air-fuel ratio of each cylinder is corrected to the rich side, and then the ignition timing correction is performed in step S361. The ignition timing of each cylinder is retarded. In this refresh mode operation, the air-fuel ratio correction amount and the ignition timing correction amount may be set smaller than those in the temperature increase mode operation.

Then, as in the case of the temperature rising mode operation, the secondary air is supplied, but here, the output of the air pump 32 is adjusted to the smaller side, and the secondary air is reduced in quantity. Is supplied to the exhaust pipe 14. By reducing the amount of secondary air in this way, the amount of oxygen decreases, and the combustion amount of unburned HC supplied to the exhaust pipe 14 decreases due to air-fuel ratio correction. Since it suffices to maintain the temperature TCAT at a predetermined temperature T1 (650 ° C), the amount of secondary air is reduced here, and the minimum amount of secondary air required for combustion to maintain the predetermined temperature T1 (650 ° C) is supplied. I am trying.

By reducing the amount of secondary air in this way, a large amount of HC remains in the exhaust gas without being burned when the air-fuel ratio is corrected to the rich side. The remaining HC reacts with the purifying ability-reducing substance burned and removed from the NOx catalyst 13a at high temperature. As a result, the substance with reduced purification capacity is reliably removed without adhering to the NOx catalyst 13a again.

When performing the above-mentioned air-fuel ratio correction, ignition timing correction, and secondary air supply, if these corrections or supply are abruptly made, the operating state of the engine body 1 may fluctuate,
Since the driving feeling may be deteriorated, it is preferable to gradually approach the correction value or the supply value. As described above, the NOx catalyst 13a is also heated to remove the substance having a reduced purification capacity by performing the oxygen addition control for supplying the secondary air to the exhaust pipe 14 after the air-fuel ratio of the engine body 1 is corrected to the rich side. can do.

By the way, in the first and second embodiments, the NOx catalyst 13a is heated by using the catalyst temperature raising means for performing the combustion control of the engine body 1 such as the ignition timing correction and the air-fuel ratio correction. It is also possible to raise the temperature without performing such combustion control. Hereinafter, Examples 3 to 5 using a catalyst temperature raising means that does not control the engine body 1 will be described with reference to FIGS. 5 to 10.

In these exhaust gas catalyst devices of Examples 3 to 5, in the exhaust gas purification catalyst device shown in FIG. 1, instead of the exhaust gas purification catalyst 13, as shown in FIGS. The accompanying exhaust gas purification catalysts 131, 132,
It is configured to include 133. In the third and fourth embodiments, the heating control of the NOx catalyst 13a itself is adopted as the catalyst temperature raising means.

The exhaust purification catalyst device of the third embodiment includes an exhaust purification catalyst 131 as shown in FIG. 5, and this exhaust purification catalyst 131 is provided with a burner 4 upstream of the NOx catalyst 13a.
Has 0. This burner 40 is used for the fuel injection nozzle 4
2 and an ignition device 44, and the fuel injection nozzle 42 and the ignition device 44 are operated in response to a command from the ECU 23. Fuel injection nozzle 4
2, a fuel tube 46 is connected, and the fuel tube 46 is connected to a fuel tank (not shown).

A fuel injection nozzle B48 connected to a fuel tank (not shown) via a fuel pipe 49 is provided further upstream of the burner 40 so that fuel can be injected into the exhaust purification catalyst 131. ing. The fuel injected from the fuel injection nozzle B48 is preferably the same as the fuel (gasoline or the like) supplied to the engine body 1. The fuel injection nozzle B for supplying the fuel
By omitting 48 and injecting a large amount of fuel from the fuel injection nozzle 42 for the burner 40, the exhaust purification catalyst 13
1 may be supplied with fuel.

Exhaust gas purification catalyst 131 configured as described above
In the exhaust gas purification catalyst device including the NOx catalyst 13 by changing only the control contents of the temperature increase mode operation and the refresh mode operation in the flowcharts shown in FIGS. 2 and 3.
The refresh control of a is performed. Hereinafter, the refresh control in the third embodiment will be described. The steps other than the temperature raising mode operation and the refresh mode operation are as shown in FIGS. 2 and 3, and since those steps have been described above, the second embodiment will be described. Similar to the case, the description is omitted here.

First, in the temperature raising mode operation, as shown in FIG. 8, in step S242, the fuel injection nozzle 42
The fuel is injected from the fuel source, the fuel is ignited by the ignition device 44 and burned, and the burner 40 is operated (burner operation). At this time, the fuel burns in the presence of residual oxygen in the exhaust pipe 14, but an air intake valve (not shown) that opens in conjunction with the operation of the fuel injection nozzle 42 is used for fuel injection. If it is provided near the nozzle 42,
Better combustion is obtained. When the burner 40 is operated in this way, the flame thereof heats the NOx catalyst 13a, the temperature of the NOx catalyst 13a rapidly rises, and the catalyst temperature TCAT rapidly reaches the predetermined temperature T1 (650 ° C.). .

Next, in the refresh mode operation, in step S342, the burner 40 is continuously operated to maintain the catalyst temperature TCAT at the predetermined temperature T1 (650 ° C.). This sufficiently burns and removes the substance with reduced purification ability. At this time, the opening degree of the fuel injection nozzle 42 is changed so that the fuel injection amount from the fuel injection nozzle 42 is changed to the predetermined temperature T.
It is preferable to squeeze only to the minimum amount necessary to maintain 1 (650 ° C).

Then, in step S362, fuel (gasoline or the like) is separately injected from the fuel injection nozzle B48 to forcibly mix the fuel with the exhaust gas. As a result, the exhaust gas passing through the NOx catalyst 13a contains a large amount of HC, and the purification capacity-reducing substance that is burned and removed from the NOx catalyst 13a reacts with this HC at a high temperature to ensure that the purification capacity-reducing substance is present. Will be removed.

The exhaust purification catalyst device of the fourth embodiment is provided with an exhaust purification catalyst 132 as shown in FIG. 6, and this exhaust purification catalyst 132 has a NOx catalyst 13a '. The NOx catalyst 13a 'is a conductor that generates heat when energized. For example, a heat wire having a high resistance value is embedded inside the NOx catalyst. This NOx catalyst 13a 'is connected to the lead wire 54.
It is connected to the battery 50 by a and 54b, and a relay switch 52 for switching ON / OFF of energization is interposed on the circuit thereof. The relay switch 52 is connected to the ECU 23, and is switched according to a command from the ECU 23. The battery 50 may share a normal battery for an electric system mounted on a vehicle, but since the amount of electric power used increases due to heat generation, the battery 50 may be provided separately.

Further, N is provided upstream of the NOx catalyst 13a '.
The above-mentioned fuel injection nozzle B48 for injecting fuel into the Ox catalyst 13a ′ is provided, and this fuel injection nozzle B4
Reference numeral 8 is connected to a fuel tank (not shown) via a fuel hose 49. In the exhaust gas purification catalyst device configured as described above, as in the case of the third embodiment, only the control contents of the temperature raising mode operation and the refresh mode operation in the flowcharts shown in FIGS. 2 and 3 are changed. Refresh control of the NOx catalyst 13a 'is performed.

First, in the temperature rising mode operation, as shown in FIG. 9, in step S243, the relay switch 52 is operated.
Is turned on, and a current is passed through the NOx catalyst 13a '(catalyst energization). As a result, the NOx catalyst 13a ′ itself generates heat, the temperature of the NOx catalyst 13a ′ rapidly rises, and the catalyst temperature TCAT reaches the predetermined temperature T1 (650 ° C.).

Next, in the refresh mode operation, in step S343, the energization of the NOx catalyst 13a 'is continued and the catalyst temperature TCAT is maintained at the predetermined temperature T1 (650 ° C). At this time, the energization amount to the NOx catalyst 13a 'is set smaller than that in the temperature rising mode operation, and the predetermined temperature T1
It is preferable to suppress the calorific value to the minimum necessary for maintaining (650 ° C.).

Then, in step S363, fuel (gasoline or the like) is injected from the fuel injection nozzle B48,
Fuel is compulsorily mixed into the exhaust gas. As a result, as in the case of the third embodiment, the exhaust gas passing through the NOx catalyst 13a contains a large amount of HC, and thus the NOx catalyst 13a.
The purification capacity-reducing substance that is burned and removed from the HC reacts with this HC at a high temperature, and the purification capability-reducing substance is reliably removed.

In the fifth embodiment, exhaust gas flow rate control is adopted as the catalyst temperature raising means. The exhaust purification catalyst device of the fifth embodiment includes an exhaust purification catalyst 133 as shown in FIG. 7, and the exhaust purification catalyst 133 has a throttle valve 60 in the exhaust pipe 14 downstream of the NOx catalyst 13a. There is. A valve drive device 62 is connected to the throttle valve 60, and the valve drive device 62 opens and closes the throttle valve 60 within a predetermined opening range in response to a command from the ECU 23 to reduce the exhaust passage area of the exhaust pipe 14. It is supposed to change. When the valve drive device 62 is deenergized, the throttle valve 60 is opened to the maximum, and exhaust is performed in a normal exhaust passage area.

As described above, the fuel injection nozzle B48 for injecting fuel into the NOx catalyst 13a is provided upstream of the NOx catalyst 13a.
Reference numeral 48 is connected to a fuel tank (not shown) via a fuel hose 49. In the exhaust gas purification catalyst device configured in this manner, only the control contents of the temperature raising mode operation and the refresh mode operation in the flowcharts shown in FIGS. 2 and 3 are changed in the same manner as in the third and fourth embodiments. Then NO
The refresh control of the x catalyst 13a is performed.

First, in the temperature raising mode operation, as shown in FIG. 10, in step S244, the valve driving device 62 is energized to operate the throttle valve 60 to the valve opening side to a predetermined opening degree, thereby exhausting. Reduce the passage area (exhaust passage throttle). When the area of the exhaust passage is narrowed in this way, the exhaust gas does not easily pass through the throttle valve 60, and the flow velocity of the exhaust gas as a whole slows down, so that the time the exhaust gas stays in the NOx catalyst 13a becomes long, and the exhaust gas Of the heat is easily transferred to the NOx catalyst 13a. And this heat causes NO
x As the catalyst 13a is heated, the catalyst temperature T
The CAT reaches the predetermined temperature T1 (650 ° C).

Next, in the refresh mode operation, in step S344, the throttle valve 60 is kept operating,
The NOx catalyst 13a is maintained at a predetermined temperature T1 (650 ° C). At this time, the opening degree of the throttle valve 60 is set to be larger than that in the temperature increasing mode operation, and the heat transfer amount due to the retention of the exhaust gas is set to the minimum necessary amount for maintaining the predetermined temperature T1 (650 ° C). It is preferable to suppress

Then, in step S364, fuel (gasoline, etc.) is injected from the fuel injection nozzle B48,
Fuel is compulsorily mixed into the exhaust gas. As a result, as in the case of the third and fourth embodiments, the purifying ability lowering substance burned and removed from the NOx catalyst 13a reacts with the HC, and the purifying ability lowering substance is surely removed. As described above in detail, according to the first or second embodiment, the NOx catalyst 13a can be easily controlled by performing the temperature control of the combustion gas of the engine body 1 and the oxygen addition control of the exhaust gas.
The temperature TCAT can be raised to a predetermined temperature T1 (650 ° C.), and the substance with reduced purification ability can be removed well. Further, according to the third to fifth embodiments, N
By performing the heating control of the Ox catalyst 13a itself and the flow velocity control of the exhaust gas, it is possible to reliably raise the temperature of the NOx catalyst 13a without deteriorating the operating state of the engine body 1 and the first and second embodiments. As in the case of (3), it is possible to satisfactorily remove the substance having reduced purification ability.

In the above-described embodiment, the attached amount estimating means for estimating the attached amount of the purification capacity lowering substance based on the traveling distance D is used. Even if the adhered amount is estimated based on the integrated amount and further the operating time of the engine body 1 and the like, the same effect as the estimation based on the traveling distance D can be obtained. In this case, the fuel consumption integrated amount is determined by the pulse width of the current supplied to the fuel injection valves 3a and 3b, and the intake air integrated amount is calculated by the Karman vortex type air flow sensor 6
The integrated value of the number of eddy pulses of is calculated and obtained. As for the operating time, for example, a timer may be used to measure the time during which the engine body 1 is operating.

In the above embodiment, all the determination results of the operation state determination in step S16, the catalyst temperature determination in step S30, and the elapsed time determination in step S32 are Yes (affirmative) for the duration of the refresh operation. ), And the cumulative time CST is counted up only when the refresh operation is performed satisfactorily, but the invention is not limited to this. For example, the operation state determination result of step S16 and the catalyst temperature TCAT of step S30 are used. If only the determination result of Yes is affirmative, or if the determination result of step S16 and the determination result of the elapsed time t at step S32 are only affirmative, the cumulative time CST is incremented. Also has the same effect. Also,
Sufficient effect can be expected even if the determination is made only based on the determination result of the operating state in step S16.

Further, in the above-mentioned embodiment, the cycle of the refresh operation is set every time the purifying ability lowering substance reaches a predetermined amount.
That is, it is assumed that the traveling distance D reaches the predetermined value D1.
Since the NOx catalyst 13a deteriorates as the usage time becomes longer, it is more effective to gradually reduce each predetermined value and shorten the implementation period. Further, in the above embodiment, the engine body 1 is a V-type 6-cylinder engine, but there is no limitation by the number of cylinders or the engine type (for example, horizontally opposed type), and any number of cylinders and any engine can be used. The format is also applicable.

Further, according to the present invention, the exhaust manifold 11
A larger effect can be expected by providing a heat insulating material having high heat insulation around a and 11b.

[0084]

As is apparent from the above description, according to the exhaust gas purification catalyst device of the first aspect of the present invention, the nitrogen oxide in the exhaust gas is disposed in the exhaust passage of the internal combustion engine and is in the lean combustion operation. In an exhaust gas purification catalyst device for an internal combustion engine equipped with an exhaust gas purification catalyst that adsorbs, an adhesion amount estimation means for estimating the adhesion amount of the purification performance lowering substance adhering to the exhaust purification catalyst, and an adhesion amount estimated by the adhesion amount estimation means. When the predetermined amount is attached, the catalyst temperature raising means is provided for controlling the temperature of the combustion gas in the internal combustion engine to raise the temperature of the exhaust purification catalyst, and the catalyst temperature raising means is the ignition timing of the internal combustion engine. Since it includes ignition timing correction means for correcting the ignition timing correction amount to the retard side by the retard amount set based on the engine rotation speed and the engine load of the internal combustion engine, it is adsorbed on the exhaust purification catalyst and If the amount of adherence of the substance that reduces the purification capacity that reduces the conversion ability is estimated well, and the amount of adherence exceeds the predetermined amount, the ignition timing of the internal combustion engine is corrected to the retard side, and the heat of the combustion gas increases in temperature. The temperature of the exhaust purification catalyst is raised and the substances with reduced purification ability are satisfactorily combusted and removed from the exhaust purification catalyst. Therefore, the ability of adsorbing nitrogen oxides on the exhaust purification catalyst is restored. The retardation amount can be properly set according to the engine rotation speed and the engine load, and the deterioration of the engine operating state at the time of retarding the ignition timing can be preferably prevented.

According to the exhaust purification catalyst device of the second aspect, in the first aspect, the catalyst temperature raising means increases the intake air amount to the internal combustion engine when the ignition timing is retarded. The intake air amount correction unit includes the amount correction unit, and the intake air amount correction unit sets the increase correction amount of the intake air based on the engine rotation speed and the engine load of the internal combustion engine.
By increasing the intake air amount, the air amount can be appropriately compensated, and it is possible to preferably prevent the engine output from decreasing when the ignition timing is retarded.

According to the exhaust purification catalyst device of the third aspect, the internal combustion engine is provided with the exhaust purification catalyst which is arranged in the exhaust passage of the internal combustion engine and adsorbs nitrogen oxides in the exhaust gas during lean combustion operation. In an exhaust gas purification catalyst device, an adhesion amount estimating means for estimating an adhesion amount of a purification performance lowering substance adhering to an exhaust purification catalyst, and an internal combustion engine when the adhesion amount estimated by the adhesion amount estimating means reaches a predetermined adhesion amount. And a catalyst temperature raising means for increasing the temperature of the exhaust gas purification catalyst by controlling the temperature of the combustion gas in the engine, and the catalyst temperature raising means includes an ignition timing correction means for correcting the ignition timing of the internal combustion engine to the retard side. An intake air amount correction means for increasing the intake air amount to the internal combustion engine when the ignition timing is retarded, and the intake air amount correction means is based on the engine rotation speed and the engine load. Since the increased correction amount of the intake air is set, the amount of the adhering amount of the purifying ability-decreasing substance that is adsorbed by the exhaust purifying catalyst and reduces the purifying ability of nitrogen oxides is well estimated, and the adhering amount exceeds the predetermined adhering amount. When the ignition timing of the internal combustion engine is corrected to the retard side, the temperature of the exhaust purification catalyst is raised by the heat of the combustion gas whose temperature rises, and the substances with reduced purification ability are combusted and removed from the exhaust purification catalyst satisfactorily. The ability of the purification catalyst to adsorb nitrogen oxides will be restored, but at this time, it is possible to properly supplement the intake air amount by increasing the intake air amount and decrease the engine output when the ignition timing is retarded. Can be preferably prevented.

According to the exhaust purification catalyst device of the fourth aspect, in the third aspect, the ignition timing correction means sets the retard amount of the ignition timing based on the engine rotation speed and the engine load of the internal combustion engine. Therefore, the retard amount of the ignition timing can be appropriately set according to the engine rotation speed and the engine load, and the deterioration of the engine operating state at the time of retarding the ignition timing can be preferably prevented.

Further, according to the exhaust purification catalyst device of claim 5, in claim 1 or 3, the catalyst temperature raising means sets the air-fuel ratio to the stoichiometric air-fuel ratio when the temperature of the exhaust purification catalyst reaches a predetermined temperature. Since the exhaust purification catalyst is raised in temperature by controlling the temperature of the combustion gas in the internal combustion engine, the catalyst temperature is raised to a predetermined temperature rise temperature since the combustion control device further includes switching means for switching to rich combustion operation with a rich side air-fuel ratio including When it reaches, the rich combustion operation can be performed so that the exhaust gas contains a large amount of unburned hydrocarbons. Therefore, the unburned hydrocarbons and the purifying ability reducing substance are reacted at a high temperature, and the purifying ability reducing substance is reacted. Can be satisfactorily removed from the exhaust purification catalyst.

According to the exhaust purification catalyst device of the sixth aspect, in the fifth aspect, the rich side air-fuel ratio is set based on the engine rotation speed and the engine load. Accordingly, the air-fuel ratio for removing the substance with reduced purification capability can be set appropriately, and the substance with reduced purification capability can be reliably removed. Further, according to the exhaust purification catalyst device of claim 7, in claim 2 or 3, at least one of the intake air amount correction means and the ignition timing correction means changes from the control target value before correction to the control target value after correction. According to the exhaust gas purification catalyst device of claim 8, the intake air amount correction means and the ignition timing correction means are configured so that the control target value after correction is corrected to the control target after correction. According to the exhaust gas purifying catalyst device of claim 9, the ignition timing correcting means gradually switches from the ignition timing before correction to the ignition timing after correction. According to the exhaust purification catalyst device of claim 10, the correction to the rich side air-fuel ratio in claim 5 is performed rapidly because the pre-correction air-fuel ratio is gradually changed to the corrected air-fuel ratio. Engine by correction The operating state of the body can be suitably suppressed that variation occurs, it is possible to prevent deterioration of the driving feeling.

According to the exhaust purification catalyst device of the eleventh aspect, in the first or third aspect, the catalyst temperature raising means is operated when the operating state of the internal combustion engine is within the predetermined engine rotation speed range and the predetermined load range. Therefore, the catalyst temperature can be satisfactorily carried out in a stable operating state.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an internal combustion engine including an exhaust gas purification catalyst device to which an embodiment of the present invention is applied.

2 is a part of a flowchart of a refresh control routine of a first embodiment executed by an electronic control unit (ECU) of FIG.

3 is the rest of the flowchart of the refresh control routine that follows the flowchart shown in FIG.

FIG. 4 is a diagram showing steps of a temperature rising mode operation and a refresh mode operation in the flowchart of the refresh control routine of the second embodiment.

FIG. 5 is a diagram showing an exhaust purification catalyst of Example 3;

FIG. 6 is a diagram showing an exhaust purification catalyst of Example 4;

FIG. 7 is a diagram showing an exhaust purification catalyst of Example 5.

FIG. 8 is a diagram showing steps of a temperature raising mode operation and a refresh mode operation in the flowchart of the refresh control routine of the third embodiment.

FIG. 9 is a diagram showing steps of a temperature raising mode operation and a refresh mode operation in the flowchart of the refresh control routine of the fourth embodiment.

FIG. 10 is a diagram showing steps of a temperature raising mode operation and a refresh mode operation in the flowchart of the refresh control routine of the fifth embodiment.

[Explanation of symbols]

1 engine body 1a One side (left side) bank 1b Bank on the other side (right side) 3a Fuel injection valve 3b Fuel injection valve 6 Air flow sensor 8 ISC (idle speed control) valve 12 Air-fuel ratio sensor 13 Exhaust purification catalyst 13a NOx catalyst 13a 'NOx catalyst 13b Three-way catalyst 16a spark plug 16b spark plug 18 Crank angle sensor 23 Electronic Control Unit (ECU) 25 distance meter 26 Catalyst temperature sensor 30 Secondary air inlet pipe 32 air pump 40 burners 48 Fuel injection nozzle B 50 battery 54 lead wire 60 throttle valve 131 Exhaust purification catalyst 132 Exhaust purification catalyst 133 exhaust purification catalyst

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 41/04 305 F02D 41/04 305C 45/00 314 45/00 314R (72) Inventor Kazuhide Tsugai 5-3-33 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Ren Hirako Ren 5-33-8 Shiba, Minato-ku, Tokyo (72) Inventor Shogo Omori Tokyo 5-33-8 Shiba, Minato-ku, Mitsubishi Motors Co., Ltd. (72) Inventor Daisuke Sanbayashi 5-33-8, Shiba, Minato-ku, Tokyo (72) Inventor, Yoshiaki Kodama Tokyo Metropolitan Port 5-33, Shiba-ku, Mitsubishi Motors Industry Co., Ltd. (72) Inventor, Kazuo Koga F-term, 5-33-8, Shiba 5-33, Shiba, Minato-ku, Tokyo (reference) 3G08 4 AA04 BA09 BA17 BA24 DA10 EA07 EA11 EB12 EC03 FA01 FA02 FA04 FA09 FA10 FA20 FA26 FA27 FA38 3G091 AA02 AA12 AB03 AB06 BA11 BA14 CB02 CB05 DA02 DA07 DB10 DC03 EA01 EA05 EA07 EA14 EA16 EA18 EA33 EA34 EA38 FC01 GA06 GB03W HA08 HA36 3G301 HA01 HA15 JA25 LA04 LB03 LC01 MA01 MA12 NA08 NC04 ND02 NE03 NE12 NE13 PA05Z PA09Z PA10Z PA11Z PD04Z PD12Z PE03Z PE08Z PG00Z PG01Z

Claims (11)

[Claims] 1. An exhaust purification catalyst device for an internal combustion engine, comprising an exhaust purification catalyst arranged in an exhaust passage of an internal combustion engine for adsorbing nitrogen oxides in exhaust gas during lean combustion operation, the exhaust purification catalyst being attached to the exhaust purification catalyst. Adhesion amount estimating means for estimating the adhesion amount of the purification performance reducing substance, and when the adhesion amount estimated by the adhesion amount estimating means reaches a predetermined adhesion amount, temperature control of the combustion gas in the internal combustion engine is performed. And a catalyst temperature raising means for raising the temperature of the exhaust purification catalyst, wherein the catalyst temperature raising means sets the ignition timing of the internal combustion engine based on the engine rotation speed and the engine load of the internal combustion engine. An exhaust gas purification catalyst device for an internal combustion engine, comprising an ignition timing correction means for correcting the retard amount by a retard amount. 2. The catalyst temperature raising means includes an intake air amount correcting means for increasing an intake air amount to the internal combustion engine when the ignition timing is retarded, and the intake air amount correcting means includes: The exhaust gas purification catalyst device for an internal combustion engine according to claim 1, wherein the increase correction amount of the intake air is set based on an engine rotation speed and an engine load of the internal combustion engine. 3. An exhaust purification catalyst device for an internal combustion engine, which is disposed in an exhaust passage of an internal combustion engine and includes an exhaust purification catalyst for adsorbing nitrogen oxides in exhaust gas during lean combustion operation, wherein the exhaust purification catalyst is attached to the exhaust purification catalyst. Adhesion amount estimating means for estimating the adhesion amount of the purification performance reducing substance, and when the adhesion amount estimated by the adhesion amount estimating means reaches a predetermined adhesion amount, temperature control of the combustion gas in the internal combustion engine is performed. And a catalyst temperature raising means for raising the temperature of the exhaust purification catalyst, wherein the catalyst temperature raising means includes an ignition timing correction means for correcting the ignition timing of the internal combustion engine to a retard side, and a delay of the ignition timing. Intake air amount correction means for increasing the intake air amount to the internal combustion engine when the cornering is performed, and the intake air amount correction means is based on the engine speed and the engine load. Exhaust purification catalyst apparatus for an internal combustion engine and sets the increase correction amount of the serial intake air. 4. The ignition timing correcting means sets the retard amount of the ignition timing based on the engine speed and the engine load of the internal combustion engine.
An exhaust gas purification catalyst device for an internal combustion engine as described above. 5. The catalyst temperature raising means further comprises a switching means for switching to a rich combustion operation in which the air-fuel ratio is set to a rich side air-fuel ratio including a stoichiometric air-fuel ratio when the temperature of the exhaust purification catalyst reaches a predetermined temperature. An exhaust gas purification catalyst device for an internal combustion engine according to claim 1 or 3, characterized in that it has. 6. The exhaust gas purification catalyst device for an internal combustion engine according to claim 5, wherein the rich side air-fuel ratio is set based on an engine speed and an engine load. 7. The at least one of the intake air amount correction means and the ignition timing correction means gradually switches from a control target value before correction to a control target value after correction. 2. An exhaust purification catalyst device for an internal combustion engine according to 2 or 3. 8. The intake air amount correction means and the ignition timing correction means gradually switch from a control target value before correction to a control target value after correction. An exhaust gas purification catalyst device for an internal combustion engine as described above. 9. The exhaust gas purification catalyst device for an internal combustion engine according to claim 1, wherein the ignition timing correction means gradually switches the ignition timing before correction to the ignition timing after correction. . 10. The exhaust purification catalyst for an internal combustion engine according to claim 5, wherein the correction to the rich side air-fuel ratio is performed by gradually switching from the air-fuel ratio before correction to the air-fuel ratio after correction. apparatus. 11. The internal combustion engine according to claim 1, wherein the catalyst temperature raising means is operated within a predetermined engine rotation speed range and a predetermined load range in an operating state of the internal combustion engine. Exhaust purification catalyst device.