JP2003176716A - Exhaust emission control catalyst device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control catalyst device capable of maintaining functions of exhaust emission control catalyst without causing overheating or burning of the exhaust emission control catalyst while keeping an internal combustion engine operated even when purification ability deteriorating substances other than nitrogen oxide (NOx) are attached, and without deteriorating operating conditions. <P>SOLUTION: This device is provided with catalyst heating means (S24, S26, and S28) to heat the exhaust emission control catalyst when attached quantity of the purification ability deteriorating substances reaches a prescribed value (S12), and an operating condition detection means to detect the operating conditions of the internal combustion engine. When it is determined that the internal combustion engine is in a prescribed middle to high load operating condition, temperature rise of the exhaust emission control catalyst is permitted. When it is determined that the internal combustion engine is rather in a high load operating condition than the prescribed middle to high load operating condition, temperature rise of the exhaust emission control catalyst by the catalyst heating means is prohibited (S16). <P>COPYRIGHT: (C)2003,JPO

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 is known in which before the adsorption amount of the catalyst reaches saturation, the air-fuel ratio is switched to the rich air-fuel ratio control to control the stoichiometric air-fuel ratio or a value close to the stoichiometric air-fuel ratio, and NOx is reduced in a reducing atmosphere (rich state). (For example, see Patent Document 1).

In this air-fuel ratio control method, the timing of switching from the lean combustion operation to the rich combustion operation is controlled based on the elapsed time from the start of the lean air-fuel ratio control, and when the predetermined time has elapsed, the rich air-fuel ratio is controlled. After switching to control, NO adsorbed on the catalyst by rich air-fuel ratio control
When the reduction of x is completed, the control is returned to the lean air-fuel ratio control. By alternately repeating the lean combustion operation and the rich combustion operation in this way, the adsorption capacity of the NOx catalyst is maintained and the NOx amount is reduced. I am trying.

[0005]

[Patent Document 1] Japanese Unexamined Patent Publication No. 5-133260

[0006]

The substance adsorbed on the NOx catalyst may be only NOx, but actually substances other than NOx, such as sulfur and its compounds, also adhere. Such substances other than NOx (hereinafter referred to as purifying ability lowering substances) will be absorbed in the place where NOx should be adsorbed.
Therefore, the NOx adsorption capacity is reduced as a result.

Thus, NOx adhering to the NOx catalyst
Other purification capacity-reducing substances cannot be removed even if the air-fuel ratio control as disclosed in the above-mentioned publication is performed, and the amount of adhered and deposited substances increases with the passage of time. If the deposition of such a substance lowering the purification capability is left as it is, the NOx adsorption capability will only decrease, and the NOx catalyst may not fully perform its function.

The present invention has been made to solve the above problems, and an object of the present invention is to operate an internal combustion engine even if substances other than nitrogen oxides (NOx) that reduce the purifying ability adhere. An object of the present invention is to provide an exhaust gas purification catalyst device capable of maintaining the function of the exhaust gas purification catalyst (NOx catalyst) without overheating and burning of the exhaust gas purification catalyst (NOx catalyst) without deteriorating the operating state.

[0009]

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,
A catalyst heating unit that raises the temperature of the exhaust purification catalyst when the adhesion amount estimated by the adhesion amount estimation unit reaches a predetermined adhesion amount, and an operation state detection unit that detects an operation state of the internal combustion engine. When the operating state detecting means determines that the internal combustion engine is in a predetermined medium-high load operating state, the catalyst heating means allows the temperature of the exhaust purification catalyst to rise, and the internal combustion engine operates in the predetermined medium-high load state. When it is determined that the operating condition is higher than the loaded operating condition, the temperature rise of the exhaust purification catalyst by the catalyst heating means is prohibited.

As a result, the adhered amount of the purifying ability lowering substance which is adsorbed on the exhaust purifying catalyst and deteriorates the purifying ability of nitrogen oxides is estimated by the adhering amount estimating means, and when the adhering amount exceeds the predetermined adhering amount, The temperature of the exhaust purification catalyst is raised by the catalyst heating means, the purification capacity lowering substance is satisfactorily burned and removed from the exhaust purification catalyst, and the adsorption ability of nitrogen oxides on the exhaust purification catalyst is restored. When the catalyst heating means heats the exhaust purification catalyst by adjusting, for example, the operating state (air-fuel ratio, etc.) of the internal combustion engine, the temperature of the exhaust purification catalyst is raised when the operating state of the engine is at a predetermined level. It is carried out when the engine is operating under a stable load operating condition, and it is prohibited when the engine operating condition is higher than the predetermined medium / high load operating condition. Heating of the exhaust purification catalyst with is locked, burning is prevented.

Further, the invention of claim 2 is characterized in that the catalyst heating means raises the temperature of the exhaust purification catalyst by adjusting the operating state of the internal combustion engine. As a result, the adhered amount of the purifying ability-decreasing substance that is adsorbed on the exhaust purification catalyst and deteriorates the purifying ability of nitrogen oxides is estimated by the adhering amount estimating means, and when the adhering amount exceeds the predetermined adhering amount, the internal combustion engine By adjusting the operating conditions (air-fuel ratio, etc.), the temperature of the exhaust purification catalyst rises, the substances with reduced purification ability are burned and removed from the exhaust purification catalyst satisfactorily, and the adsorption ability of nitrogen oxides on the exhaust purification catalyst is restored. However, at this time, the temperature rise of the exhaust purification catalyst by adjusting the operating state of the internal combustion engine (air-fuel ratio, etc.) is carried out when the operating state of the engine is stable at a predetermined medium-high load operating state,
This is prohibited when the operating state of the engine is higher than the predetermined medium / high load operating state, preventing deterioration of the operating state and preventing heating and burning of the exhaust purification catalyst.

Further, the invention of claim 3 is characterized in that the catalyst heating means supplies fuel and air to the exhaust purification catalyst. As a result, the adhered amount of the purifying ability-decreasing substance that is adsorbed on the exhaust purification catalyst and deteriorates the purifying ability of nitrogen oxides is estimated by the adhering amount estimating means, and when the adhering amount exceeds the predetermined adhering amount, the internal combustion engine Fuel and air are supplied to the exhaust purification catalyst by adjusting the operating state (air-fuel ratio, etc.), and this fuel burns in the exhaust purification catalyst in the presence of air, whereby the temperature of the exhaust purification catalyst rapidly rises, The substances with reduced purification ability are satisfactorily combusted and removed from the exhaust purification catalyst, and the ability to adsorb nitrogen oxides on the exhaust purification catalyst is restored. At this time, it is necessary to adjust the operating state (air-fuel ratio, etc.) of the internal combustion engine. The temperature rise of the exhaust purification catalyst by supplying fuel and air to the exhaust purification catalyst, which is one aspect, is performed when the operating state of the engine is stable in a predetermined medium-high load operating state. Rolling state when in the operating state of high load than the predetermined medium and high load operation state is prohibited, the heating of the exhaust gas purifying catalyst with the deterioration of the operating state can be prevented, burning is prevented.

Further, in the invention of claim 4, the operating state detecting means detects at least the engine rotation speed and the volume efficiency as a load correlation value, and when the load correlation value is within a predetermined range, the internal combustion engine is It is characterized in that it is determined to be in a medium / high load operating state, and if it exceeds the predetermined range, it is determined to be in a higher load operating state than the medium / high load operating state.

Thus, whether the engine is in a predetermined medium-high load operating state or a higher load than that is easily determined at least by the engine rotation speed and the volumetric efficiency, and the catalyst heating means operates in the operating state of, for example, an internal combustion engine ( If the temperature of the exhaust purification catalyst is raised by adjusting the air-fuel ratio, etc., the temperature of the exhaust purification catalyst should be stable until the engine operating condition is stable at least within the prescribed range of engine rotation speed and volume efficiency. It is carried out during the operation, and is prohibited when the operation is under a high load beyond a predetermined range.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 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, V
This is a 6-cylinder gasoline engine body, and the intake system, ignition system, etc., including the combustion chamber, 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. An intake pipe 9 including a sensor 6, a throttle valve 7, an ISC (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 speed, and the engine load L due to the operation of an air conditioner (not shown)
The valve opening is adjusted according to the fluctuation of e to change the intake air amount and stabilize the idling operation. Further, this ISC valve 8 is operated to the valve opening side during the air-fuel ratio correction control described later, and acts to compensate for the output decrease due to the air-fuel ratio correction execution.

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. The exhaust purification catalyst 13 is N
Two catalysts, an Ox catalyst 13a and a three-way catalyst 13b, are provided, and the NOx catalyst 13a is arranged upstream of the three-way catalyst 13b. The NOx catalyst 13a adsorbs NOx (nitrogen oxide) in an oxidizing atmosphere to generate HC.
In a reducing atmosphere in which (hydrocarbons) are present, NOx is converted to N ₂
It has a function of reducing to (nitrogen) and the like. NOx
As the catalyst 13a, for example, Pt having heat deterioration resistance is used.
And a catalyst composed of an alkaline rare earth such as lanthanum and cerium is used. A catalyst temperature sensor 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. The catalyst temperature sensor 26 can also function as a means for estimating the exhaust temperature from the engine body 1.

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 for detecting the atmospheric pressure Pa, and reference numeral 22 is an intake air temperature sensor for detecting the intake air temperature Ta.

The engine speed (engine speed)
Ne is calculated from the generation time interval of the crank angle synchronization signal θCR detected by the crank angle sensor 18. 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 equal to the throttle sensor 1
It is calculated from the throttle opening θTH detected by 9, the volume efficiency ηv, and the like.

An input / output device (not shown) and a storage device (ROM, RA) containing a large number of control programs are provided in the passenger compartment.
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 and 3b, the ignition unit 24, the hydraulic controller 60 of the automatic transmission 30 described later, and the like are connected, and they are calculated based on the input information from various sensors. The optimum value is output. The fuel injection valves 3a and 3b are instructed by the ECU 23,
A pulsed current is supplied for driving, and 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.

FIG. 2 shows a schematic configuration of a power plant of a vehicle equipped with an engine body 1 equipped with the above exhaust purification catalyst device and an automatic transmission (AT) 30. As shown in the figure, the automatic transmission 30 is connected to an output shaft 31 of the engine body 1, and a drive wheel (not shown) is connected to the drive shaft 50 of the automatic transmission 30 via a differential gear or the like. There is.

The automatic transmission 30 is composed of an automatic transmission main body 32 and a torque converter 33. The automatic transmission main body 32 incorporates hydraulic friction engagement elements such as hydraulic clutches and hydraulic brakes in addition to a plurality of sets of planetary gears, but the description thereof is omitted here. Torque converter 33
Is a fluid coupling, and includes housing 33, casing 34,
It is composed of a pump 36, a turbine 37, a stator 38 and the like. The casing 34 is connected to the output shaft 31 and rotates in synchronization with the output shaft 31.
Further, the turbine 37 is connected to the input shaft 3 of the automatic transmission main body 32.
9, the stator 38 is attached to the housing 33 via a one-way clutch (not shown).

The casing 34 is filled with hydraulic oil. This hydraulic oil is discharged by the pump 36 that rotates together with the output shaft 31, and rotates the turbine 37. As a result, the torque converter 33 functions as a fluid coupling, and the output of the engine body 1 is transmitted to the drive wheels (not shown) via the automatic transmission body 32.

Between the casing 34 and the turbine 37,
A wet single-plate damper clutch 40 is interposed, and when the damper clutch 40 is engaged, the output shaft 31
Can be directly connected to the input shaft 39. When the damper clutch 40 is engaged, the output from the output shaft 31 is directly transmitted to the input shaft 39 without using hydraulic oil. In this case, the torque converter 33 does not function as a fluid coupling. It will be.

An oil passage 42 extends from between the turbine 37 of the casing 34 and the damper clutch 40, and an oil passage 46 extends from between the casing 34 and the damper clutch 40. The oil passage 42 and the oil passage 46 are connected to a control valve (not shown) in the hydraulic controller 60, and the control valve is connected to a hydraulic source (not shown) that supplies hydraulic oil of a predetermined pressure. The hydraulic oil supplied from this hydraulic power source circulates through the oil passage 42 and the oil passage 46 via the control valve, and the control valve is duty-controlled in accordance with the output signal of the ECU 23, thereby The circulation direction can be switched.

When the circulation direction is from the oil passage 46 to the oil passage 42, the working oil from the hydraulic source is supplied between the casing 34 and the damper clutch 40 through the oil passage 46, while Hydraulic fluid is discharged from the oil passage 42 between the turbine 37 and the damper clutch 40. As a result, the pressure between the casing 34 and the damper clutch 40 is increased, and the damper clutch 40 is pressed toward the disengaged side to be in the non-direct connection state. In this non-direct connection state, the torque converter 33 functions as a normal fluid coupling.

On the contrary, when the circulation direction is from the oil passage 42 to the oil passage 46, the working oil from the hydraulic pressure source is supplied between the turbine 37 and the damper clutch 40 through the oil passage 42. Meanwhile, the casing 34 and the damper clutch 40
The hydraulic oil between them is discharged from the oil passage 46. As a result, the pressure of the hydraulic oil between the turbine 37 and the damper clutch 40 increases, and the damper clutch 40 is pressed and engaged, and the direct connection state is established. In such a direct connection state, the output of the output shaft 31 is directly transmitted to the input shaft 39 of the automatic transmission main body 32.

Next, the operation of the exhaust gas purification catalyst device constructed as described above will be described with reference to FIGS. 3 to 9. The flowcharts shown in FIGS. 3 and 4 show the refresh control procedure executed by the ECU 23. This refresh control is performed when the NOx catalyst 13a is determined to have reached a predetermined amount, such as sulfur or its compounds, other than NOx adhering to the NOx catalyst 13a (substances for reducing purification capacity).
Fuel and air are supplied to a to burn this fuel, and NO
The refresh operation (catalyst heating means) for heating the x-catalyst 13a to a high temperature state is carried out, and the substance whose purifying ability is deteriorated is reduced to 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 adhering substance having a reduced purification capacity increases substantially in proportion to the fuel consumption integrated amount F of the engine body 1, so the pulse widths of the currents for driving the fuel injection valves 3a, 3b are integrated and calculated. Thus, the cumulative fuel consumption amount F is obtained, and the amount of the purification capacity lowering substance deposited and deposited on the NOx catalyst 13a is estimated based on the cumulative fuel consumption amount F (adhesion amount estimation means).

The fuel consumption integrated amount F may be obtained by integrating all the pulse widths of the drive current supplied to the fuel injection valve 3, but the NOx catalyst 13a does not adhere to the purification capacity lowering substance. However, it tends to increase in the case of the lean combustion operation, so it is preferable to limit the integration only when the lean combustion operation is being performed. Further, even if the temperature of the NOx catalyst 13a is lower than or equal to the predetermined temperature, the purifying ability-reducing substance is likely to adhere to the NOx catalyst 13a.
If the pulse width is integrated only when the temperature is equal to or lower than a predetermined temperature, the amount of the substance with reduced purification ability attached can be estimated more appropriately.

Next, in step S12, it is determined whether or not the purification capacity lowering substance has reached a predetermined amount, by whether or not the fuel consumption integrated amount F calculated in step S10 is a predetermined value F1 or more. This predetermined value F1 is set to an appropriate value through experiments, etc., and is within a range in which the amount of adhering purifying ability-reducing substances does not exceed the allowable amount, that is, the NOx emission amount that increases due to adhering of purifying ability-lowering substances is a regulated value according to laws and regulations. It is set to a value within the range not exceeding. If the determination result is Yes (affirmative),
It can be determined that the amount of the substance with reduced purification capacity exceeds the predetermined amount, and the process proceeds to step S16. On the other hand, if the determination result is No (negative) and the cumulative fuel consumption amount F has not reached the predetermined value F1, the process proceeds to step S14.

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 the purpose of vehicle maintenance 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 capacity-reducing substance estimated based on the accumulated fuel consumption amount F and the travel distance D which will be described later is temporarily reset to zero value, and the estimated value of the adhered amount and the actual adhered amount are It is implemented to prevent the inconsistency with.

If the determination result in step S14 is No (negative), the battery is connected, but the determination result of the fuel consumption integrated amount F in step S12 has not reached the predetermined value F1 yet. The determination can be made, and in this case, the routine is terminated without doing anything. On the other hand, the determination result is Ye
In the case of s (affirmative) and immediately after reconnecting the battery, the process proceeds to step S16 similarly to the determination result of Yes (affirmative) in step S12. Even if the battery is removed, EC
With the backup function of U23, etc., the cumulative fuel consumption F
When the values such as the travel distance D and the travel distance D are surely stored and held, 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 signal values from various sensors which are operating state detecting means. Here, the engine speed Ne (load correlation value), the volumetric efficiency ηv (load correlation value) that is a calculation element of the engine load Le, and the cooling water temperature TW are the targets of determination, and their respective values are (1) to (3) below. ), It is determined whether or not it falls within the range of the inequality.

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, for example, the condition for executing the refresh operation is set to the medium-high load operating state in which the operating state of the engine body 1 is changed from the medium load region to the high load region.
This is because if the refresh operation is performed in a low load range smaller than Ne1 and ηv1, the output of the engine body 1 may not be stable and the driving feeling may be deteriorated.
Further, in a high load region where the values of Ne and ηv are larger than Ne2 and ηv2, the exhaust gas temperature is high, which causes N
Since the Ox catalyst 13a is also in a high temperature state, if the refresh operation is performed in this state, the NOx catalyst 13a
This is because a 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 S16 again.
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 S22.

Step S22 is a step for releasing the AT (automatic transmission) direct connection. Here, the control valve of the hydraulic controller 60 is duty-controlled,
The engagement of the damper clutch 40 of the automatic transmission 30 is released to bring it into a non-direct connection state. As a result, the torque converter 33
Will function as a normal fluid coupling. By releasing the direct connection of the damper clutch 40 in this way, the output fluctuation of the engine body 1 caused by the execution of the refresh operation described later is not directly transmitted to the automatic transmission 30 and the driving feeling is deteriorated. It can be prevented.
It should be noted that, at the time of executing this step S22, the damper clutch 4
If 0 is already in the non-direct connection state, the non-direct connection state will be continued.

The subsequent step S24 and subsequent steps are steps for executing the refresh operation. Steps S24 to S28 are steps that constitute the temperature raising mode operation of the refresh operation, and here, the temperature TCAT of the NOx catalyst 13a is set to a predetermined temperature T1 (which is sufficient to burn and remove the substance with reduced purification ability from the NOx catalyst 13a). For example, 650
(° C).

First, in step S24, air-fuel ratio correction control is performed for each cylinder. This air-fuel ratio correction is performed for some cylinders of the engine body 1 (for example, # 1, # 3, # 5 cylinders) for lean combustion operation with a high air-fuel ratio and a large amount of air, while for the remaining cylinders (for example, , # 2, # 4, # 6 cylinders) are controlled to a rich combustion operation with a low air-fuel ratio and a large amount of fuel.

As an air-fuel ratio correction method for the lean burn operation and the rich burn operation, as to the lean burn operation side,
The fuel amount is reduced under a constant air amount, while the air amount is reduced under a constant fuel amount on the rich combustion operation side. Specifically, for lean burn operation, the air-fuel ratio is corrected based on the following equation (4), and for rich burn operation, the air-fuel ratio is corrected based on the following equation (5).

LAF = AVAF + AVAF × DAF / 100 (4) RAF = AVAF−AVAF × DAF / 100 (5) where LAF is the lean air-fuel ratio, RAF is the rich air-fuel ratio, and DAF is the air-fuel ratio correction. The amount (%) is shown. Also,
AVAF represents the average air-fuel ratio of the lean air-fuel ratio and the rich air-fuel ratio, and is set here to a value of 14.7 which is the theoretical air-fuel ratio, for example. The air-fuel ratio correction amount DAF (%) is set using a map (not shown) stored in advance based on the engine rotation speed Ne and the volumetric efficiency ηv detected at the start of the refresh operation.

As described above, when a plurality of cylinders of the engine body 1 are made to perform lean combustion operation and the remaining cylinders are made to perform rich combustion operation, such operations at different air-fuel ratios are carried out substantially at the same time.
The exhaust gas emitted from the engine body 1 includes exhaust gas containing air, that is, residual oxygen, discharged from the cylinders that have performed lean combustion operation, and unburned hydrocarbons (unburned hydrocarbons that have not been discharged from the cylinders that have performed rich combustion operation). Exhaust gas containing HC and CO will be mixed. Then, these exhaust gases are supplied to the NOx catalyst 13a via the exhaust pipe 14.

The exhaust gas containing unburned HC and residual oxygen is
The air-fuel ratio, that is, the actual average air-fuel ratio is constantly monitored based on the detection signal of the air-fuel ratio sensor 12. And
When the detected value of this air-fuel ratio does not match the above-mentioned average air-fuel ratio AVAF, the fuel is supplied to some of the cylinders that are performing lean combustion operation and / or the remaining cylinders that are performing rich combustion operation. The fuel amount or air amount to be adjusted is appropriately corrected so that the actual average air-fuel ratio and the average air-fuel ratio AVAF match.

Unburned HC supplied to the NOx catalyst 13a
Since the NOx catalyst 13a is heated by the heat of the exhaust gas, the NOx catalyst 13a is burned by the presence of the residual oxygen in the NOx catalyst 13a, and the temperature of the NOx catalyst 13a is rapidly increased. In this temperature raising mode operation, since the average air-fuel ratio AVAF of the exhaust gas is set to 14.7, its combustion is good and the NOx catalyst 1 does not increase pollutants in the exhaust gas.
The temperature of 3a can be raised.

By the way, normally, in lean combustion operation, the engine output becomes small because the fuel supply amount is small, while in rich combustion operation, a high output is generated because the fuel supply amount is sufficient. Therefore, when performing the air-fuel ratio correction for each cylinder as described above, the selection of the cylinder that performs lean combustion operation and the cylinder that performs rich combustion operation is poor,
If the combustion in the lean-burn operation continues or the combustion in the rich-burn operation continues due to the relationship of the ignition order of the cylinders, the engine output becomes uneven, which deteriorates the operation feeling. Therefore, in order to eliminate such an inconvenience, the cylinder that performs the lean combustion operation and the cylinder that performs the rich combustion operation are selected so that the lean combustion operation and the rich combustion operation are alternately performed with good balance. It

For example, when the engine body 1 is a V-type 6-cylinder engine as in the present embodiment, the ignition sequence of the cylinders is normally # 1- # 2- # as shown in the cylinder arrangement diagram of FIG. Three
Since the order is # 4- # 5- # 6, the lean combustion operation is performed for the three cylinders # 1, # 3, and # 5 of the left bank 1a that burn every other place, and the #c of the right bank 1b #. 2, #
The four cylinders # 4 and # 6 are controlled to perform the rich combustion operation.

Further, in the case of an engine body 1'such as an in-line 6-cylinder engine, the ignition order of the cylinders is usually # 1- # 5- # 3- # 6-, as shown in the cylinder arrangement diagram of FIG. #
2- # 4 or # 1- # 4- # 2- # 6- # 3- # 5
The order is # 1, so every other burns # 1, # 2, # 3
Lean combustion operation was performed for the 3 cylinders of
The four cylinders # 4, # 5, and # 6 may be controlled to perform the rich combustion operation.

It should be noted that the selection of the lean-burn operating cylinder and the rich-burn operating cylinder does not necessarily have to allocate half of the number of cylinders. For example, two of the six cylinders are set to the lean-burn operation, and the remaining four cylinders are used. The cylinder may be set to rich combustion operation. Further, the present invention can be applied not only to the engine main body 1 of an even number cylinder such as 6 cylinders but also to the engine main body 1 of an odd number cylinder such as 5 cylinders. However, the air-fuel ratio or the like may be adjusted so that the exhausted residual oxygen and the unburned HC amount are appropriate.

After the air-fuel ratio correction is performed as described above, the process proceeds to step S26. In step S26, the ignition timing is suitably corrected in accordance with the execution of the air-fuel ratio correction control. During lean burn operation, advancing the ignition timing to accelerate combustion can improve combustion efficiency, while during rich burn operation, retarding the ignition timing to delay combustion can prevent knocking, etc. Can be prevented. Therefore, the ignition timing is advanced for the cylinders performing the lean combustion operation, and the ignition timing is retarded for the cylinders performing the rich combustion operation.

Specifically, for lean burn operation, the ignition timing is advanced based on the following equation (6), and for rich burn operation, the ignition timing is retarded based on the following equation (7). L ignition timing = O / L ignition timing−k × (LAF−O / L target AF) (6) R ignition timing = O / L ignition timing + k × (O / L target AF-RAF) (7) L ignition timing is the ignition timing for lean combustion operation, and
The ignition timing is the ignition timing of the rich combustion operation, and the O / L ignition timing is the ignition timing of the normal lean combustion operation.
L target AF indicates a target air-fuel ratio during normal lean combustion operation, and k is a proportional constant obtained by experiments or the like. The above equations are respectively the above-mentioned lean air-fuel ratio LAF.
Alternatively, since the rich air-fuel ratio RAF is included, L
The ignition timing and the R ignition timing are also based on the engine rotation speed Ne and the volume efficiency ηv described above, similarly to the LAF and RAF.

After the ignition timing is corrected, the process proceeds to step S28. In step S28, the ISC valve 8
Is adjusted to the valve open side to correct the intake air amount. This intake air amount correction is such that the air-fuel ratio correction control described above reduces the fuel amount to a constant air amount on the lean combustion operation side and reduces the air amount to a constant fuel amount on the rich combustion operation side. However, since it reduces the engine output as a whole, it is implemented for the purpose of preventing this output reduction. By this correction, the intake air amount is increased, and the engine output can be stably maintained constant.

The intake air correction amount is set using a map stored in advance based on the engine rotation speed Ne and the volumetric efficiency ηv, similarly to the air-fuel ratio correction amount DAF. When performing the above-mentioned air-fuel ratio correction, ignition timing correction, and intake air amount correction, if these corrections are abruptly performed, the operating state of the engine body 1 may change, so the correction values are gradually approached. It is desirable to carry out

When the temperature increasing mode operation of the refresh operation is carried out 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.) is determined. If the determination result is No (negative), the catalyst temperature TCAT is the predetermined temperature T1 (6
If the temperature is less than 50 ° 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 for the operating state of the engine body 1 to stabilize. 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 at which the clocking is started when the refresh operation is started has passed a predetermined 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, similarly to the temperature increase mode operation described above, first, the air-fuel ratio is corrected in step S34, the ignition timing is corrected in step S36, and the intake air amount correction is performed in step S38.

First, in step S34, the air-fuel ratio is corrected, but unlike the case of the temperature increase mode operation, the average air-fuel ratio AVAF is set to the rich air-fuel ratio side, and its value is, for example, 13 .7. And
Using the value of this average air-fuel ratio (13.7), the above equation
The lean air-fuel ratio LAF and the rich air-fuel ratio RAF are obtained from (4) and the equation (5), and the air-fuel ratio of each cylinder is corrected based on these.

By setting AVAF to the rich side in this way, the exhaust gas contains a larger amount of CO and HC than in the temperature rising mode operation. Then, these CO and HC react with the purifying ability-reducing substance that has been burned and removed at a high temperature, whereby the purifying ability-reducing substance is satisfactorily released. Further, since this HC reduces NOx, the NOx adsorbed on the NOx catalyst 13a is also removed at the same time.

In step S36, the lean air-fuel ratio LAF and the rich air-fuel ratio RAF corrected and set in step S34 are adjusted in accordance with the above equations (6) and (7) in the same manner as in the temperature increasing mode operation. The L ignition timing of the combustion operation and the R ignition timing of the rich combustion operation are suitably corrected. Then, in step S38, the ISC valve 8 is adjusted to the open side to correct the intake air amount to compensate for the decrease in the engine output, as in the case of the temperature increase mode operation.

When the refresh mode operation is completed, the process proceeds to step S40, the flag f (RF) is set to the value 1 to store that the refresh mode operation has been executed, and the process proceeds to step S42. In step S42,
Every time step S42 is executed, the cumulative time CST is calculated by the following equation (8), and the catalyst temperature TCAT is the predetermined temperature T1.
(650 ° C.) is exceeded, and the continuation time of the refresh operation after the lapse of a fixed time ts (5 seconds) from the start 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 thus added is compared with a predetermined value XC corresponding to a predetermined time t1 (for example, 600 seconds) set in advance by an experiment or the like in the next step S44, and the refresh operation is predetermined. Time t1 (60
It is determined whether or not it has been 0 seconds). This predetermined time t1 (600 seconds) is the time when it can be considered that the substance with reduced purification capacity has been sufficiently removed. The determination result is No (negative)
If the cumulative time CST has not reached the predetermined value XC,
It can be determined that the removal of the substance with reduced purification capacity is not sufficient, and the process returns to step S16 to continue the refresh operation.

When 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 kept in a good operating state for refresh operation. If so, the process proceeds to step 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, even though 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).

If 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 purification capacity-reducing substance has been substantially completely removed, and the refresh operation can be performed. After driving,
Finally, step S46 is executed. In step S46, the values of the accumulated time CST, the accumulated fuel consumption amount F, and the flag f (RF) that have been accumulated are reset to zero values upon completion of the refresh operation, and further the AT direct connection release is reset to reset the automatic transmission. The damper clutch 40 of 30 can be directly connected. This prepares for the next refresh operation.

By the way, in the above embodiment, the adhered amount of the purifying ability lowering substance is estimated based on the fuel consumption integrated amount F, but in addition to this, the traveling distance D, the intake air integrated amount A, the engine body Even if it is estimated based on the operating time H of 1, the same effect as that obtained by the consumed fuel integrated amount F can be obtained. In this case, the traveling distance D is calculated by the distance meter 25, and the intake air integrated amount A is calculated by calculating the integrated value of the vortex pulse number of the Karman vortex type air flow sensor 6. Regarding the operating time H, for example, a timer may be used to measure the time during which the engine body 1 is operating.

In order to estimate the adhered amount of the purifying ability lowering substance based on the traveling distance D, as shown in FIG. 5, steps S10 and S12 which are the adhered amount estimating means in the above-mentioned refresh control flowchart are executed. These are replaced by step S100 for calculating the traveling distance D and step S120 for determining whether or not the traveling distance D has reached a predetermined value D1 (for example, 1000 km). Further, instead of resetting the integrated fuel amount F in step S46, the travel distance D is reset to a zero value in step S46.
Replace with 0.

Further, in the case of estimating the adhered amount of the purification capacity lowering substance by the intake air integrated amount A, as shown in FIG. 6, in the refresh control flowchart, the adhered amount estimating means, ie, step S10 and step S12. Are replaced with step S101 for calculating the intake air integrated amount A and step S121 for determining whether or not the intake air integrated amount A has reached a predetermined value A1. Further, instead of resetting the fuel integrated amount F in step S46, it is replaced with step S461 for resetting the intake air integrated amount A to a zero value.

Similarly, in the case of estimating the operating time H, as shown in FIG. 7, the step S102 for calculating the operating time H and the operating time H by the adhering amount estimating means of the flowchart of the refresh control are set to predetermined values. H
It is replaced with step S122 for determining whether or not it has reached 1, and further with step S462 for resetting the operating time H to a zero value instead of resetting the integrated fuel amount F in step S46.

As described above in detail, the lean combustion and the rich combustion are performed for each cylinder, and unburned H in the exhaust gas.
Air-fuel ratio correction control is performed so that C and oxygen are simultaneously included, and unburned HC is burned in the NOx catalyst 13a to generate NO.
Since the refresh operation for raising the temperature of the x-catalyst 13a is performed, the purifying ability lowering substance adhering to the NOx catalyst 13a is satisfactorily combusted and removed from the NOx catalyst 13a by the combustion heat. As a result, the NOx adsorption capacity of the NOx catalyst 13a is regenerated and the NOx purification efficiency is restored. Further, during the refresh mode operation, H is contained in the exhaust gas passing through the NOx catalyst 13a.
Since C is included, this HC causes N
Ox is also well reduced and removed.

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 purification capacity lowering substance reaches a predetermined amount.
That is, the fuel consumption integrated amount F reaches a predetermined value F1 (a predetermined value D1 for the traveling distance D, a predetermined value A1 for the intake air integrated amount A, and a predetermined value H1 for the operating time H), but the NOx catalyst 13a is used. Since deterioration progresses as the time becomes longer, it is more effective to gradually reduce each predetermined value and shorten the execution period.

Further, in the above embodiment, the engine body 1
Is a V-type 6-cylinder engine, but it is not limited by the number of cylinders and engine type (for example, horizontally opposed type), and any number of cylinders and any engine type can be applied.

[0076]

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 of an internal combustion engine having an exhaust gas purification catalyst that adsorbs, the amount of the purification capacity lowering substance that is adsorbed by the exhaust gas purification catalyst and reduces the purification capability of nitrogen oxides is estimated by the deposition amount estimation means, When the adhered amount exceeds the predetermined adhered amount, the temperature of the exhaust purification catalyst is raised by the catalyst heating means, and the substance having reduced purification ability is burned and removed satisfactorily from the exhaust purification catalyst, and the adsorption of nitrogen oxides on the exhaust purification catalyst. The capacity will be restored, but at this time, if the catalyst heating means is to heat the exhaust purification catalyst by adjusting the operating state (air-fuel ratio etc.) of the internal combustion engine, for example, The temperature of the air purifying catalyst is raised when the engine operating condition is stable under a predetermined medium-high load operating condition, and when the engine operating condition is under a higher load than the predetermined medium-high load operating condition. Since it is prohibited, it is possible to prevent deterioration of the operating condition by not raising the temperature of the exhaust purification catalyst when the operating condition of the engine is not stable, and to prevent heating and burning of the exhaust purification catalyst. it can.

Further, according to the exhaust purification catalyst device of the second aspect, the catalyst heating means adjusts the operating state of the internal combustion engine to raise the temperature of the exhaust purification catalyst, so that the catalyst is adsorbed on the exhaust purification catalyst and is oxidized by nitrogen. The adhered amount of the purifying ability reducing substance that deteriorates the purifying ability of the object is estimated by the adhered amount estimating means, and when the adhered amount exceeds a predetermined adhered amount, the exhaust gas is purified by adjusting the operating state (air-fuel ratio etc.) of the internal combustion engine. The temperature of the catalyst rises, the substances with reduced purification ability are burned and removed from the exhaust purification catalyst satisfactorily, and the adsorption ability of nitrogen oxides on the exhaust purification catalyst is restored, but at this time, the operating state of the internal combustion engine ( The temperature of the exhaust purification catalyst is raised by adjusting the air-fuel ratio, etc.) when the engine operating condition is stable under the specified medium / high load operating condition. It is prohibited when the engine is operating with a higher load than the engine operating condition. Therefore, when the engine operating condition is not stable, the operating condition (air-fuel ratio, etc.) of the internal combustion engine should not be adjusted to prevent the operating condition from deteriorating. In addition, the exhaust purification catalyst can be prevented from being heated and burnt out.

According to the exhaust purification catalyst device of the third aspect, since the catalyst heating means supplies the exhaust purification catalyst with fuel and air, it is adsorbed by the exhaust purification catalyst and reduces the purification ability of nitrogen oxides. The adhered amount of the purification capacity lowering substance is estimated by the adhered amount estimating means, and when the adhered amount exceeds a predetermined adhered amount, fuel and air are supplied to the exhaust purification catalyst by adjusting the operating state (air-fuel ratio etc.) of the internal combustion engine. When this fuel burns in the exhaust purification catalyst in the presence of air, the temperature of the exhaust purification catalyst rises rapidly, and substances with reduced purification ability are burned and removed satisfactorily from the exhaust purification catalyst to the exhaust purification catalyst. The ability to adsorb nitrogen oxides in the exhaust gas will be restored, but at this time, the exhaust purification catalyst by supplying fuel and air to the exhaust purification catalyst, which is one mode of adjusting the operating state (air-fuel ratio etc.) of the internal combustion engine, Is carried out when the operating condition of the engine is stable under a predetermined medium-high load operating condition, and is prohibited when the engine operating condition is under a higher load than the predetermined medium-high load operating condition. Therefore, when the operating condition of the engine is not stable, the supply of fuel and air to the exhaust purification catalyst is not carried out to prevent deterioration of the operating condition, and also to prevent heating and burning of the exhaust purification catalyst. be able to.

Further, according to the exhaust purification catalyst device of the fourth aspect, the operating state detecting means detects at least the engine speed and the volume efficiency as the load correlation value, and when the load correlation value is within the predetermined range, It is determined that the internal combustion engine is in a medium-high load operating state, and if it exceeds the predetermined range, it is determined that the internal combustion engine is in a higher-load operating state than the medium-high load operating state.
It is possible to easily determine whether the engine is in a predetermined medium-high load operation state or a higher load than that by at least the engine speed and the volume efficiency.

[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.

FIG. 2 is a schematic configuration diagram of a power plant of a vehicle equipped with an internal combustion engine equipped with an exhaust purification catalyst device.

3 is a part of a flowchart of a refresh control routine executed by an electronic control unit (ECU) shown in FIG.

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

FIG. 5 is a part of a flow chart of a refresh control routine in which the estimation means for estimating the amount of adherence of a substance having a reduced purification capacity is replaced with the estimation based on the travel distance.

FIG. 6 is a part of a flowchart of a refresh control routine in the case where the estimation means of the amount of adherence of a substance having a reduced purification capacity is replaced with the estimation by the integrated amount of intake air.

FIG. 7 is a part of a flow chart of a refresh control routine in the case where the amount estimation means of the substance having a reduced purification capacity is replaced with the estimation based on the operation time.

8 is a schematic diagram showing a cylinder arrangement of the V-type 6-cylinder engine shown in FIG. 1. FIG.

FIG. 9 is a schematic diagram showing a cylinder arrangement of an in-line 6-cylinder engine.

[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 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 Automatic transmission (AT) 33 Torque converter 40 damper clutch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhide Tsugai             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. (72) Inventor Hirako Ren             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. (72) Inventor Shogo Omori             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. (72) Inventor Daisuke Mibayashi             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. (72) Inventor Yoshiaki Kodama             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. (72) Inventor Kazuo Koga             Mitsubishi Motors, 5-3-8 Shiba, Minato-ku, Tokyo             Industry Co., Ltd. F-term (reference) 3G084 BA04 BA09 BA17 BA32 DA10                       DA19 DA22 EA11 EB12 EC03                       FA01 FA02 FA09 FA10 FA20                       FA27 FA29 FA33 FA38                 3G091 AA02 AA17 AA29 AB03 AB06                       BA11 BA14 CB02 CB05 CB07                       DA02 DA10 DB10 DB11 DC03                       EA01 EA05 EA06 EA07 EA14                       EA18 EA30 EA34 FA14 FB03                       FB12 FC01 GA06 GB04W                       HA08 HA36                 3G301 HA01 HA08 JA25 JA33 KA09                       LA04 LB02 LC01 MA01 NA08                       NA09 NC04 ND02 NE11 NE12                       NE13 NE15 NE23 PA05Z                       PA09Z PA10Z PA11Z PD04A                       PD12Z PE03Z PE08Z

Claims (4)

[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. An adhering amount estimating means for estimating an adhering amount of the purification capacity lowering substance, and a catalyst heating means for increasing the temperature of the exhaust purification catalyst when the adhering amount estimated by the adhering amount estimating means reaches a predetermined adhering amount; The exhaust gas purifying by the catalyst heating means when the operating state detecting means detects the operating state of the internal combustion engine, and the operating state detecting means determines that the internal combustion engine is in a predetermined medium-high load operating state. When it is determined that the internal combustion engine is in a higher load operating state than the predetermined medium and high load operating state while allowing the catalyst temperature rise, Exhaust purification catalyst apparatus for an internal combustion engine and inhibits the temperature rise of the exhaust gas purifying catalyst by the catalyst heating means. 2. The exhaust gas purification catalyst device for an internal combustion engine according to claim 1, wherein the catalyst heating means adjusts an operating state of the internal combustion engine to raise the temperature of the exhaust gas purification catalyst. 3. The catalyst heating means supplies fuel and air to the exhaust purification catalyst.
An exhaust gas purification catalyst device for an internal combustion engine as described above. 4. The operating state detecting means detects at least engine speed and volume efficiency as a load correlation value, and when the load correlation value is within a predetermined range, the internal combustion engine is in the medium-high load operating state. 4. If it is determined that the operating condition is higher than the medium and high load operating condition when the predetermined range is exceeded, it is determined that the operating condition is higher.
9. An exhaust gas purification catalyst device for an internal combustion engine according to any one of 1.