DE10311708A1 - Exhaust gas control device of an internal combustion engine and exhaust gas control method - Google Patents

Abstract

An exhaust control device determines whether an exhaust control catalyst is in a partially activated state when a temperature of the exhaust control catalyst is low in an activation temperature range and the temperature needs to be raised, and supplies a reducing agent to raise a temperature of the exhaust control catalyst when it is determined that Exhaust control catalytic converter is in the partially activated state. In addition, the exhaust gas control device is characterized in that a determination of whether the exhaust gas control catalytic converter is activated is carried out depending on whether the temperature of the exhaust gas control catalytic converter is increased by the supply of the reducing agent after the reducing agent has been supplied to increase the temperature.

Description

Background of the Invention 1. Field of the Invention

The invention relates to an exhaust gas control device Internal combustion engine. In particular, the invention relates to an exhaust control device in which an exhaust control catalyst in an exhaust system of an internal combustion engine is provided, and to an exhaust gas control process.

2. Description of the related prior art

In an internal combustion engine with lean combustion caused by a diesel engine is embodied is a Exhaust control catalytic converter such as a storage reduction NOx catalyst provided in its exhaust system, and nitrogen oxides (NOx) contained in the exhaust gas are replaced by a Oxidation and reduction process of the exhaust gas control catalytic converter cleaned.

The storage reduction NOx catalyst carries a NOx absorbent (catalytic substance) and has the ability to purify exhaust gas by converting nitrogen oxides (NOx) to harmless nitrogen (N ₂ ), water vapor (H ₂ O) and carbon dioxide ( CO ₂ ) can be cleaned by absorbing nitrogen oxides (NOx) contained in the exhaust gas when an oxygen concentration in the exhaust gas is high and by reducing the absorbed nitrogen oxides (NOx) to nitrogen dioxide (NO ₂ ) and nitrogen monoxide (NO) and exhausted into the exhaust gas when the oxygen concentration in the exhaust gas is low (lean), namely when an air / fuel ratio of the exhaust gas is small (rich) while the nitrogen dioxide (NO ₂ ) and nitrogen monoxide (NO) react with unburned fuel components (CO, HC) contained in the exhaust gas.

Temperature control is also important in an exhaust gas control catalytic converter of this type. In addition, the temperature of the exhaust gas control catalyst must be kept at or above an activation temperature so as to promote the purification of the above-mentioned nitrogen oxide (NOx) through an oxidation and reduction process. As shown in FIG. 7, where the storage reduction NOx catalyst is an example to describe the activation, the storage reduction NOx catalyst is activated at a temperature equal to or greater than about 250 ° C in which purification of nitrogen oxide (NOx) is mainly possible by the above-mentioned oxidation-reduction reaction.

Meanwhile, the internal combustion engine becomes leaner Combustion usually means combustion in an atmosphere carried out, where there is an excess of oxygen. Accordingly, the oxygen concentration in the exhaust gas, which is left out due to the combustion, rarely to that Reduced level at which the process of reduction and Omitting is encouraged, and a lot of the unburned Fuel components (CO, HC) is extremely low in that Exhaust gas is included.

Therefore, a reducing agent supply device is in the Exhaust system of the internal combustion engine with lean combustion intended. This reducing agent supply device injects Fuel the engine as a reducing agent in that Exhaust gas, which is the oxygen concentration contained therein reduced while there are hydrocarbons (HC) than that supplies unburned fuel components, causing the Exhaust control process described above is promoted.

A temperature of the exhaust control catalyst is also low when the engine is cold-started. Moreover an exhaust gas control rate indicates a small value after the Internal combustion engine was started until the temperature of the Exhaust control catalytic converter in an area of a Activation temperature increases when the exhaust gas flows in. Therefore, a temperature increase control is usually used carried out at a temperature of in the Exhaust control catalyst flowing exhaust gas inevitably increased is activated so that the exhaust gas control catalytic converter is activated earlier.

As an example of the temperature increase control Example one disclosed in JP-A-10-73018 Temperature increase control known. According to this Disclosure is with a Main fuel injection control of an internal combustion engine an increase amount correction is initially performed, and a Reduction ratio of an automatic transmission with a Output shaft of the internal combustion engine is coupled so that reduces the internal combustion engine at low speeds and high torque is operated. Then the Exhaust control catalytic converter activated earlier, by that Exhaust gas with high temperature caused by an operation at low speeds and high torque is omitted and flows into the exhaust gas control catalytic converter.

In this case, the Main fuel injection control on one Fuel injection control to get one Engine delivery, and the amount of injection is given a required torque, a temperature of a Engine coolant, a temperature of an intake air, an intake air amount and the like in corresponding Situations calculated and determined.

However, if the engine is cold, that is Temperature control of the exhaust gas control catalytic converter is required, then it is not just the exhaust gas control catalytic converter but also the engine body cold, and the operation in this state is unstable compared to that operation, after the engine has warmed up. Accordingly an engine control to stabilize the combustion carried out. Since also for the Main fuel injection control required parameters such as for example the temperature of the engine coolant, the The temperature of the intake air and the amount of intake air decrease during of a cold start is a complicated control required to increase the temperature of the exhaust gas during stable combustion is maintained.

Because if the engine is cold, and if that Exhaust control catalytic converter temperature must then be increased it is difficult to stabilize the engine control the combustion to the temperature increase control to increase to match the temperature of the exhaust gas. Therefore, the Coordination between the engine control and the Temperature increase control according to the specifications of the Internal combustion engine adapted to the respective situation become. Accordingly, when developing a Internal combustion engine a novel technique for increasing one Desired temperature that the conventional Temperature increase control replaced.

Meanwhile, the timing for starting the Reductant supply to promote the exhaust control process so be set that the activated state of the Exhaust gas catalytic converter is sufficiently taken into account. Accordingly, the temperature of the in the Exhaust gas control catalyst flowing through an exhaust gas Exhaust gas temperature sensor monitored. If the exhaust gas temperature, at which the exhaust gas control catalytic converter can be regarded as activated can, after starting the engine is detected, then determines that the exhaust control catalyst has been activated, and the supply of the reducing agent to promote cleaning of the Nitrogen oxides (NOx) or the like is started. Since however the temperature of the flowing into the exhaust gas control catalytic converter Exhaust gas depending on the operating state at the changing situation, it is not always possible determine exactly whether the exhaust control catalyst is activated based on the exhaust gas temperature.

Summary of the invention

It is the object of the invention to provide an exhaust gas control device for a To provide an internal combustion engine and an exhaust gas control method, at which the temperature of the exhaust gas control catalytic converter increases early can be without an operating state of a Engine body is affected.

According to a first aspect of the invention has an exhaust gas control device an exhaust gas control catalytic converter which is located in an exhaust gas path Internal combustion engine is provided and cleans exhaust gas, the Temperature is increased to an activation temperature range; a reducing agent supply device for supplying a Reducing agent to the exhaust gas control catalyst and for conveying an exhaust control process of the exhaust control catalyst; a Catalyst temperature increasing device for supplying a Reducing agent for raising a temperature, the Exhaust control catalytic converter is partially activated, whereby this Supply from the supply of the reducing agent to promote the Exhaust control process distinguishes and increases the temperature of the exhaust gas control catalytic converter by reducing a catalytic substance caused by the exhaust gas control catalytic converter is carried, and the supplied reducing agent; and a Determination device of a partially activated state for Determine whether the exhaust control catalyst is in a partial activated state. In the case of the exhaust gas control unit, the Determination device of the partially activated state, whether the exhaust control catalytic converter in the partially activated state is when the temperature of the exhaust control catalyst is low in the activation temperature range and the temperature needs to be raised. If it is determined that the Exhaust control catalytic converter is in the partially activated state, then the reducing agent becomes to raise a temperature fed to the exhaust gas control catalyst.

According to the first aspect, the structure described above the determining device determines the partial activated state whether the exhaust gas control catalyst in the partially activated state is when the temperature of the Exhaust control catalytic converter in terms of Activation temperature range is low and can be increased got to. If it is determined that the exhaust gas control catalyst is in the partially activated state, then it will Reducing agent for raising a temperature of the Exhaust gas control catalyst supplied. And that is the temperature the exhaust control catalytic converter not by increasing the Temperature of the exhaust gas flowing into the exhaust control catalytic converter increased, but by the supply of the reducing agent to the Exhaust gas control catalyst. Accordingly, the temperature of the Exhaust control catalytic converter can be increased early without the Operating state of the engine body is affected.

The "partially activated state" mentioned above corresponds to a state before the whole Exhaust control catalyst is activated, and also that State in which the temperature of the exhaust gas control catalytic converter can be increased by the reaction with the reducing agent. If the reducing agent is supplied in this state, then the reducing agent reacts in the partially activated Range, and the temperature of the exhaust gas control catalyst will increased by the heat of reaction.

In addition, the determination device of the partial activated state an exhaust gas temperature sensor for outgoing Have gas that detects a temperature of the exhaust gas, which flows out of the exhaust gas control catalyst, and one Exhaust gas temperature sensor for incoming gas, which is a temperature of exhaust gas captured in the exhaust control catalytic converter flows in, and it can determine that the Exhaust control catalytic converter is in the partially activated state, if both the exhaust gas temperature sensor for outgoing gas and the Exhaust gas temperature sensor for incoming gas an exhaust gas temperature detected, in which the exhaust gas control catalyst as partial can be considered activated.

Furthermore, the determination device of the partial activated state the exhaust gas temperature sensor for incoming Include gas, which is the temperature of the in the Exhaust gas control catalyst flowing exhaust gas is detected, and a Recording device that is one in the exhaust gas control catalytic converter amount of exhaust gas flowing at the start of the engine and records, and it can determine that the Exhaust control catalytic converter is in the partially activated state, if the exhaust gas temperature sensor for incoming gas is a Exhaust gas temperature recorded at which the exhaust gas control catalyst as can be viewed partially activated, and in which the built-in value recorded in the recorder a flow rate is reached at which the Exhaust control catalytic converter can be regarded as partially activated can.

Accuracy is according to the structures described above improved in determining whether the Exhaust control catalytic converter is in the partially activated state, and HC poisoning due to the supply of the reducing agent before activating the exhaust gas control catalytic converter, it is avoided by using at least two parameters that the Determine whether to consider whether the exhaust control catalytic converter is in the partially activated state. HC poisoning corresponds in this case to a phenomenon in which the supplied reducing agent is not in the exhaust gas control catalyst reacts and on an end face of the exhaust control catalyst liable. Before the exhaust control catalytic converter namely the partial activated state because of a reaction between the Reducing agent and the catalytic substance by the Exhaust gas control catalytic converter is not sufficiently achieved can be detected exactly whether the exhaust gas control catalytic converter is in the partially activated state, and the HC poisoning due to the supply of the reducing agent is avoided.

The exhaust gas control device can also be equipped with a Activation determination device may be provided. This Activation determiner determines whether the Exhaust gas control catalytic converter is in the state in which one Exhaust gas cleaning can be carried out on the Basis of the temperature of the exhaust control catalytic converter flowing exhaust gas. This activation determination device can determine that the exhaust control catalyst in that state is where the exhaust gas purification can be carried out if the exhaust gas flowing out of the exhaust control catalyst Activation temperature reached or exceeded at which the Exhaust control catalytic converter due to the supply of the reducing agent be considered activated to increase a temperature can after the reducing agent to raise the temperature was fed.

With this structure, it is determined whether the exhaust gas control catalyst is in the activated state, based on the Temperature of the flowing out of the exhaust gas control catalytic converter Exhaust gas after the reducing agent to raise the temperature was fed. With this structure, the supply of Reducing agent for increasing a temperature of the Exhaust control catalyst as the supply of the reducing agent to the Determine whether the exhaust control catalyst is used in is an activated state and it is based on the actual supply of the reducing agent determines whether the Exhaust control catalytic converter is activated. Because especially the Activation determination device by the actual supply of the reducing agent determines whether the exhaust control catalyst is activated if the determination is to be carried out as to whether the exhaust control catalytic converter is activated, then a very exact determination compared to that determination obtained based on an estimate of the Exhaust gas temperature determines whether the exhaust control catalytic converter is activated.

In addition, when determining by the Activation determination device is carried out if the Temperature of the exhaust gas flowing out of the exhaust control catalyst has not reached the activation temperature, the Activation determination device determine again whether the Exhaust gas control catalytic converter is in the state in which the Exhaust gas cleaning can be done by that Reductant fed to increase a temperature again when the partially activated state of the Exhaust control catalytic converter considered to be more advanced can be.

That is, when it is determined whether the exhaust gas control catalyst is in the activated state, if the determination result is that indicates that the exhaust control catalyst is activated despite the Fact cannot be obtained that the reducing agent was supplied to raise a temperature to determine whether the exhaust gas control catalytic converter is activated can Reducing agents do not work effectively, and the HC poisoning is too possible. Accordingly, the structure Reductant fed again when the partial Activation of the exhaust gas control catalytic converter as further can be considered advanced, so the reaction of the To promote reducing agent, and the activation of the Exhaust control catalytic converter is determined again.

If, in addition, the temperature of the exhaust control catalytic converter flowing exhaust gas does not reach the activation temperature then the reference value can be used to determine whether the Exhaust control catalytic converter in the partially activated state is, by the determining device of the partially activated State larger than the previous value.

In addition, the reducing agent supply device leads regarding the supply of the reducing agent to increase the Temperature a predetermined amount of the reducing agent Exhaust control catalytic converter by a supply process in performed several times for each feeding process becomes. If the reducing agent is supplied when the Temperature is increased, then a lot of Reducing agent that is supplied with each feeding operation is compared to the amount of reducing agent supplied be reduced if the exhaust control process is promoted. Furthermore, the feeding process per unit time can be any feeding process with a higher frequency than that Feeding process performed in that feeding process when the exhaust control process is promoted.

If an injection amount of the reducing agent at a Valve opening process is reduced, then the HC Poisoning of the exhaust control catalytic converter due to the liability of the in liquid form on the end face of the exhaust gas control catalytic converter remaining reducing agent can be avoided. If also the frequency for supplying the reducing agent per unit of time is increased, then more reducing agent can be added to that Exhaust gas control catalyst are supplied. Accordingly the heat of reaction increases, which is an early increase in Temperature of the exhaust gas control catalyst allows.

In addition, if the reducing agent is supplied when the If the temperature rises, this can be the case with each feeding process supplied amount of reducing agent are increased sequentially, or the frequency of the feeding process per unit of time to be increased over time.

A second aspect of the invention relates to Exhaust gas control method for an internal combustion engine with a Exhaust gas control catalytic converter located in an exhaust gas path Internal combustion engine is provided and an exhaust gas with a Temperature cleans up to an activation temperature range is increased, and with a reducing agent supply device for supplying a reducing agent to the Exhaust gas control catalyst and for promoting an exhaust gas control process of the exhaust control catalytic converter. According to this procedure determines whether the exhaust control catalytic converter is in a partial activated state. If the temperature of the Exhaust control catalytic converter in terms of Activation temperature range is low, and the temperature must be increased, then it is determined whether the Exhaust control catalytic converter is in the partially activated state, and the reducing agent for raising a temperature of the Exhaust control catalyst is supplied when it is determined that the exhaust control catalytic converter in the partially activated state is. In this case, the supply of the reducing agent becomes Raise a temperature on the partially activated one Exhaust gas control catalyst performed, and the temperature of the Exhaust gas control catalyst is caused by a reaction between one catalytic substance generated by the exhaust gas control catalytic converter and the supplied reducing agent is carried, which increases itself from a supplied reducing agent to promote the Exhaust control process differs.

Brief description of the drawings

Fig. 1 shows a schematic view of an internal combustion engine according to an embodiment of the invention;

Fig. 2 is a schematic view showing an internal structure of a particulate filter according to the embodiment of the invention;

Fig. 3 shows a flowchart of a catalyst temperature raising control according to the embodiment of the invention;

FIG. 4A shows a schematic for describing injection control when a temperature of an exhaust control catalyst needs to be raised, and FIG. 4B shows a schematic for describing injection control when an exhaust control operation needs to be promoted;

Fig. 5A, 5B show schematic illustrations of a modified example in the injection control when the temperature of the exhaust gas control catalyst needs to be increased;

Fig. 6 is a flowchart showing a routine for determining whether the exhaust gas control catalyst is in an activated state, according to the embodiment of the invention; and

Fig. 7 is a schematic illustration showing an exhaust gas control characteristic of the exhaust gas control catalyst.

Detailed description of the preferred embodiments

Next, a preferred embodiment of one Exhaust control device of an internal combustion engine according to the invention described. The structure of one described here Exhaust gas control catalytic converter is only one exemplary embodiment the invention, and the details thereof can be according to various specifications or the like of Internal combustion engine to be changed.

First, according to the embodiment shown in FIG. 1, an exhaust gas control device 10 is provided with a lean combustion by a catalytic converter 50 and a reducing agent supply device 20 in an internal combustion engine 1 , which is embodied by a diesel engine or the like.

The catalytic converter 50 , which has a housing 51 and a plurality of exhaust gas control catalysts 52 a, 52 b, which are provided in the interior of the housing 51 , effects an exhaust gas control process for cleaning a toxic substance contained in the exhaust gas, which is discharged from the engine body 1 becomes. In particular, the housing 51 is arranged downstream of a turbine housing 4 of the internal combustion engine 1 , and the storage reduction NOx catalyst 52 a and the particle filter 52 b, which are the exhaust gas control catalysts, are accommodated one behind the other from an upstream side of the exhaust gas inside the housing 51 ,

The storage reduction NOx catalyst 52 is an example of a lean NOx catalyst provided in an exhaust system of a lean-combustion engine, and it performs an exhaust gas control process for purifying mainly nitrogen oxides (NOx) contained in the exhaust gas are included.

In particular, the storage reduction NOx catalyst can purify exhaust gas by purifying nitrogen oxides (NOx) and the like to harmless nitrogen (N ₂ ), water vapor (H ₂ O) and nitrogen dioxide (NO ₂ ) by absorbing the nitrogen oxides (NOx) contained in the exhaust gas when an oxygen concentration of the exhaust gas is large, and by reducing the absorbed nitrogen oxides (NOx) to nitrogen dioxide (NO ₂ ) and nitrogen monoxide (NO) and exhausted into the exhaust gas when the oxygen concentration in the Exhaust gas is low (lean) when an air / fuel ratio of the exhaust gas is small (rich), while the nitrogen dioxide (NO ₂ ) and nitrogen monoxide (NO) react with unburned fuel components (CO, HC) which are in the Exhaust gas are included.

The structure also uses, for example, alumina (AL ₂ O ₂ ) as a support, and at least one element is supported by the support, which is made of an alkali metal such as potassium (K), sodium (Na), lithium (Li) and cesium (Cs) and an alkaline earth such as barium (Ba) and calcium (Ca) and a rare earth such as lanthanum (La) and yttrium (Y) and a noble metal such as platinum (Pt).

A further description of the above-mentioned exhaust gas control process is as follows: In the lean-combustion engine 1 , combustion is normally performed in the atmosphere in which there is an excess of oxygen. Therefore, the oxygen concentration in the exhaust gas exhausted by the combustion is rarely reduced to the level at which the reduction and exhaust process is promoted, and the amount of the unburned fuel components (CO, HC) is extremely small, that is contained in the exhaust gas.

Therefore, in the embodiment, engine fuel (HC), which is a reducing agent, is injected into the exhaust gas to reduce the oxygen concentration, and hydrocarbons (HC), which are unburned fuel components, are supplied to the exhaust gas again to promote the exhaust gas purification process , The supply of the reducing agent during cleaning is performed by the reducing agent supply device 20 , which will be described later. In the exemplary embodiment, the reducing agent supply device according to the invention is configured by the reducing agent supply device 20 . The reducing agent supply device 20 will be described in detail later.

Meanwhile, the particulate filter 52 b is an exhaust gas control catalyst that oxidizes and burns fine particles such as soot or the like contained in the exhaust gas by the action of the catalytic substance. Specifically, the particulate filter has 52 b, a filter base material 58, as shown in FIG. 2, for example, carries an activated oxygen release agent, a catalytic substance, and it causes an exhaust gas control operation for cleaning (removing) of the exhaust gas by oxidizing and burning of the fine Particles collected on the filter base material 58 using an oxidizing force from the activated oxygen.

The filter base material 58 has a honeycomb structure shape and is made of a porous material such as cordierite. In addition, the filter base material 58 has a plurality of flow paths 55 , 56 which extend parallel to one another. In particular, the filter base material 58 has an exhaust gas inlet path 55 , the downstream end of which is blocked by a plug 55 a, and an exhaust gas path 56 , the upstream end of which is blocked by a plug 56 a. The exhaust gas inlet path 55 and the exhaust gas outlet path 56 are aligned in a longitudinal direction and in a lateral direction in the filter base material 58 via a thin partition 57 .

In addition, a support sheet made of alumina (Al ₂ O ₃ ) or the like is provided on a surface and an inner opening of the partition wall 57 . The activated oxygen solvent, which absorbs excess oxygen when there is an excess of oxygen nearby and which alternatively releases the absorbed oxygen in the form of activated oxygen when the oxygen concentration is reduced, is on the support in addition to a noble metal catalyst such as platinum ( Pt) or the like worn.

As the activated oxygen solvent, at least one Element used that consists of an alkali metal such as Potassium (K), sodium (Na), lithium (Li), cesium (Cs) and rubidium (Rb), an alkaline earth such as barium (Ba), calcium (Ca) and strontium (Sr) a rare earth such as Lanthanum (La) and yttrium (Y) and a transition metal such as Example cerium (Ce) and tin (Sn) is selected.

An alkali metal or an alkali earth is preferred uses a greater tendency towards ionization than calcium (Ca) have, namely potassium (K), lithium (Li), cesium (Cs), rubidium (Rb), barium (Ba), strontium (Sr) or the like.

In the particulate filter 52 having the structure described above, the exhaust gas initially flows sequentially through the exhaust gas inlet path 55 , the partition wall 57 and the exhaust gas outlet path 56 (as shown by an arrow a in FIG. 2) and the fine particles such as soot contained in the exhaust gas is collected on the surface of the partition 57 and inside thereof in the process of passing the partition 57 . Then, the fine particles collected on the surface of the partition 57 and inside thereof are oxidized by activated oxygen which is increased several times by changing the oxygen concentration of the exhaust gas flowing in the partition 57 (a filter base material), and are finally burned without being a bright flame is generated so that they are removed from the filter base material 58 .

It should be noted in the embodiment that when the oxygen concentration of the exhaust gas flowing into the particulate filter 52 b is changed, it is changed by injecting the engine fuel (hydrocarbons: HC), which is a type of reducing agent, from the reducing agent supply device 20 into that exhaust.

Thus, in the embodiment, nitrogen oxides (NOx) and the fine particles such as soot are contained in the exhaust gas, which is cleaned by arranging the catalytic converter 50 , the storage reduction NOx catalyst 52 a and the particle filter 52 b in one Exhaust duct 11 receives.

Next, the reducing agent supply device 20 is described, which promotes the exhaust gas control process of the storage reduction NOx catalyst 52 a and the particulate filter 52 b.

The reducing agent supply device 20 has a reducing agent supply valve 21 provided in the exhaust passage upstream of the catalytic converter 50 , an electronic control unit 22 provided in a control system of the internal combustion engine 1 , and the like.

The reducing agent supply valve 21 is an electronic check valve, and injects an appropriate amount of reducing agent into the exhaust gas at an appropriate timing according to a reducing agent supply program processed by the electronic control unit 22 . In addition, the reductant supply valve 21 is connected to an engine fuel supply system and supplies the engine fuel as a reductant that is supplied from the fuel supply system to the catalytic converter 50 .

In addition, the electronic control unit 22 calculates an amount and a timing of the reducing agent supply based on an output from an air / fuel ratio sensor 23 provided downstream of the catalytic converter 50 , from outputs from exhaust gas temperature sensors 24 a, 24 b, which at one upstream and a downstream side of the exhaust gas of the catalytic converter 50 are provided, and a change in engine operation record data that changes in accordance with the engine operation, and the like. Then, the electronic control unit 22 controls the opening and closing operation of the reducing agent supply valve 21 based on the calculated supply amount and timing. Note that the electronic control unit 22 supplies a predetermined amount of the reducing agent to the exhaust gas control catalyst 52 by performing the supply operation (valve opening valve operation) several times in each supply process in the valve opening operation of the reductant supply valve 21 .

Thus, the reducing agent supply device 20 in the embodiment injects the engine fuel that is the reducing agent into the exhaust gas so as to promote the exhaust gas control process of the storage reduction NOx catalyst 52 a and the particulate filter 52 b.

In the following description, an exhaust gas temperature sensor that is provided upstream of the catalytic converter 50 is referred to as the exhaust gas temperature sensor 24 a for incoming gas, and an exhaust gas temperature sensor that is provided downstream of the catalytic converter 50 is used as the exhaust gas temperature sensor 24 b for outgoing gas Called gas. In addition, the storage-reduction NOx catalyst 52 a and the particulate filter 52 is b collectively referred to simply as the exhaust gas control catalyst 52nd

In the exhaust emission control catalyst 52 which purifies the exhaust gas b through the action of the catalytic substance such as the storage-reduction NOx catalyst 52 a and the particulate filter 52, a temperature control is important. In the storage reduction NOx catalyst 52a as an example for the purpose of description, the catalytic substance is activated by raising the temperature to or above about 250 degrees Celsius, and purification of nitrogen oxides (NOx) is mainly by oxidation - And reduction reactions carried out effectively.

In addition, a description of the activation of the particulate filter 52 b is as follows: as can be seen from the above description, the catalytic substance (activated oxygen solvent) carried by the particulate filter 52 b has substantially the same structure as that by the storage reduction NOx Catalyst 52 a carried catalytic substance. Accordingly, the particle filter 52 b is also activated at or above approximately 250 degrees Celsius, and cleaning of the fine particles by dissolving the activated oxygen is started.

However, since the temperature of the exhaust gas control catalyst 52 is also low during a cold start of the internal combustion engine 1 , the exhaust gas control rate indicates a small value until the entire exhaust gas control catalyst 52 is activated due to an influence of the exhaust gas after the engine is started. Namely, in order to improve the exhaust gas control rate when the engine is cold, the exhaust gas control catalyst 52 needs to be activated by raising its temperature early.

Accordingly, in the exhaust control catalyst 10 according to the embodiment, catalyst temperature increase control is performed by supplying the reducing agent to raise a temperature, partially activating the exhaust control catalyst, which is different from supplying the reducing agent to promote the exhaust control operation, and by controlling the temperature of the exhaust control catalyst 52 is increased by a reaction between the catalytic substance carried by the exhaust gas control catalyst 52 and the reducing agent.

The catalyst temperature increase control performed by the exhaust control device 10 based on a temperature increase mechanism of the exhaust control catalyst 52 due to the supply of the reducing agent will be described with reference to a flow chart in FIG. 3. The routine shown in the flow chart of FIG. 3 is processed in the electronic control unit 22 of the internal combustion engine 1 , and the supply of the reducing agent in the catalyst temperature control time is performed by the reducing agent supply device 20 .

In the routine, based on a temperature of an engine coolant, it is first determined whether the current operating state corresponds to the cold start when the engine 1 is started (step S101). Specifically, if the engine coolant temperature is less than a predetermined temperature, then the current condition is considered a cold start. Alternatively, if the engine coolant temperature is greater than the predetermined temperature, then the current operating condition is considered a normal temperature start. In the embodiment, it should be noted that the predetermined temperature, which is a threshold, is set, for example, as the engine coolant temperature of approximately 40 degrees Celsius at which a warm-up of the engine body is completed.

Next, when it is determined that the current operating state corresponds to the cold start at step S101, the electronic control unit 22 sets a catalyst temperature increase flag so that the temperature increase control starts by supplying the reducing agent (step S102).

Alternatively, if it is determined that the current operating condition corresponds to the normal temperature start at step S101, then the electronic control unit 22 sets an input gas temperature increase control mark that inevitably increases the temperature of the exhaust gas flowing into the exhaust gas control catalyst 52 , in addition to the catalyst temperature increase control mark (Step S103). If the input gas temperature increase control flag is set, then the temperature increase control for the exhaust gas for increasing the temperature of the exhaust gas is performed in another routine.

If, in the embodiment, the temperature of the exhaust gas is inevitably increased, then an opening of a Air intake throttle valve that is in an air intake path is provided so that the intake air quantity reduced, and a ratio of engine fuel to of an air intake unit is increased so that an Temperature of a combustion gas increases, namely Exhaust gas temperature.

In addition, the injection timing of the Main fuel injection control of the engine in the Corrected in advance so that an ignition delay of the Engine fuel due to a reduction in Intake air quantity is eliminated. When starting at normal temperature is the combustion of the internal combustion engine relatively stable, which makes it relatively easy to use Main fuel injection control due to the Correct the temperature increase control of the exhaust gas. In In this case it should be noted that the Main fuel injection control of the Fuel injection control for each cylinder of the Internal combustion engine corresponds to that to ensure a required torque or the like is carried out, as described above.

Next, the electronic control unit 22 reads the emissions from the exhaust gas temperature sensor 24 a for incoming gas and the exhaust gas temperature sensor 24 b for outgoing gas, so as to determine whether the exhaust gas catalytic converter 52 is in the partially activated state when the catalyst temperature increase control mark in steps S102 , S103 is determined, and it determines whether the exhaust control catalyst 52 is in the partially activated state (step S104).

In this case, the "partially activated state" corresponds to a state before activation of the entire exhaust gas control catalytic converter and also a state in which the temperature of the exhaust gas control catalytic converter 52 can be increased by a reaction with the reducing agent. When the reducing agent is supplied in this state, the reducing agent reacts in the partially activated area, and the temperature of the exhaust gas control catalyst 52 is increased. With regard to the temperature increase process due to the partial activation, it is assumed that the reducing agent reacts in the state in which some of the various catalytic substances that are carried by the respective exhaust gas control catalysts 52 a, 52 b have already been activated, or in that state, in which the activation of the catalytic substance can be ensured in an area (for example, near an end face on the downstream side) of the catalytic converter 50 (exhaust gas control catalyst 52 ), and generation of heat is promoted.

According to a study conducted by the inventors using the storage reduction NOx catalyst 52 and the particulate filter 52 b as a test pattern, several cases were found in which the exhaust gas control catalyst reached the partially activated state when the temperature of the exhaust gas ( incoming gas) flowing into the catalytic converter 50 reaches 200 degrees Celsius, and when the temperature of the exhaust gas (outgoing gas) flowing out of the catalytic converter 50 exceeds 190 degrees Celsius. Accordingly, the routine determines that the exhaust control catalytic converter is in the partially activated state when the temperatures of the exhaust gas, which are detected by the respective exhaust gas temperature sensors 42 a, 24 b, meet the temperature conditions described above. It should be noted that the values used here as an example are only exemplary. The values change depending on a capacity of the catalytic converter 50 , the kind of the catalytic substance carried, and the like.

In addition, at step S104, the accuracy for determining whether the exhaust gas control catalyst is in the partially activated state is improved, and the HC poisoning due to the reducing agent supplied before the activation of the exhaust gas control catalyst is avoided by two parameters of the exhaust gas temperature sensor 24 a for incoming gas and read the exhaust gas temperature sensor 24 b for outgoing gas. Namely, since a reaction between the reducing agent and the catalytic substance carried by the exhaust control catalyst 52 cannot be sufficiently obtained before the exhaust control catalyst reaches the partially activated state, HC poisoning due to the supply of the reducing agent is avoided by accurately detecting whether the exhaust control catalyst 52 is in the partially activated state using two parameters.

Next, the electronic control unit 22 starts supplying the temperature-increasing reductant when it is determined that the exhaust gas control catalyst is in the partially activated state at step S104 (step S105). In the process of supplying the reducing agent when the temperature is raised, it should be noted that the amount of reducing agent supplied in each feeding operation is reduced compared to the amount of reducing agent that is supplied when the exhaust gas control operation is promoted. Furthermore, one feed operation per unit time is performed at a higher frequency in each feed process than that of the feed operation when the exhaust gas control operation is promoted.

Injection waveforms shown in FIGS . 4A, 4B have an injection waveform ( FIG. 4A) in the period of increasing the temperature of the exhaust gas control catalyst 52 , and an injection waveform ( FIG. 4B) in the period of promoting the exhaust gas control process. As can be seen from the injection waveform, in the ignition control for increasing the temperature of the exhaust gas control catalyst 52, the amount of the reducing agent supplied in each supplying operation (a valve opening operation) is reduced compared to that in the injection control for promoting the exhaust gas control operation. In addition, the frequency when supplying the reducing agent per unit time ( 1 / s) is greater in each supply process than when promoting the exhaust gas control process.

The reason why the temperature of the exhaust gas control catalyst 52 is increased by this type of injection control is to avoid HC poisoning of the exhaust gas control catalyst 52 due to the supply of the reducing agent to raise a temperature and to effectively raise the temperature of the exhaust gas control catalyst 52 in a short period of time. Namely, if the amount of the reducing agent injected at each supplying operation (valve opening operation) is reduced, then a cooling effect of the exhaust gas control catalyst 52 caused by the remaining reducing agent in liquid form adhering to the end surface of the exhaust gas control catalyst 52 , namely HC poisoning, can be avoided. In addition, if the frequency for supplying the reducing agent per unit time is increased, then more reducing agent can be supplied to the exhaust gas control catalyst, thereby increasing the heat of reaction. Accordingly, the temperature of the exhaust control catalyst can be effectively increased.

Thus, in the embodiment, the temperature of the exhaust control catalyst 52 is effectively increased while avoiding HC poisoning by performing the reducing agent supplying process when the exhaust control process needs to be promoted, which is different from the reducing agent supplying process when the temperature of the exhaust gas control catalytic converter must be increased.

Next, the electronic control unit 22 determines whether the temperature of the exhaust control catalyst has increased to the activation temperature range when the reducing agent is supplied to raise a temperature based on the temperature of the exhaust gas flowing out of the exhaust control catalyst 52 (step S106).

In the embodiment, the exhaust gas temperature of 250 degrees Celsius, at which the temperature of the exhaust gas catalytic converter 52 can be regarded as increased to the activation temperature range, can be set as a threshold value when the exhaust gas temperature is set, namely the threshold value for the determination. Then, when the exhaust gas temperature detected by the exhaust gas temperature sensor 24 for outgoing gas reaches 250 degrees Celsius, it is determined that the temperature of the exhaust gas control catalyst has increased to the activation area. Then, when it is determined that the exhaust gas control catalyst is in the activation temperature range at step S106, the electronic control unit 22 stops supplying the reducing agent to raise a temperature (step S107).

If the temperature of the exhaust gas has not reached 250 degrees Celsius in step S106, then it is assumed that the reducing agent supplied to raise a temperature is not effective. In the routine, the value set in step S104, namely the reference for determining whether the exhaust gas control catalyst is in the partially activated state, is set larger than the previous value so as to eliminate the HC poisoning due to the reducing agent (step S108 ). Then, the routine returns to the process at step S104 to thereafter redetermine whether the exhaust gas control catalyst is in the partially activated state at the newly set exhaust gas temperature.

The reason why the threshold value for the partially activated state is set to a higher temperature than the previous value in step S108 is to ensure a recovery time of the poisoned exhaust gas control catalytic converter 52 . If the temperature of the exhaust gas flowing out of the exhaust gas control catalytic converter does not reach the activation temperature range, then HC poisoning is possible. Accordingly, the reducing agent for increasing a temperature is supplied again when it can be assumed that the partial activation of the exhaust gas control catalyst 52 has progressed further. Therefore, HC poisoning (cooling) of the exhaust control catalyst 52 due to the repeated supply of the reducing agent is avoided.

Thus, the routine determines whether the exhaust control catalyst is in the partially activated state when the temperature can be raised by the supply of the reducing agent in the routine in step S104. Then, when it is determined that the exhaust control catalyst is in the partially activated state, the reducing agent is supplied to raise a temperature. Therefore, the temperature of the exhaust control catalyst 52 is raised early, and the exhaust control catalyst 52 can be activated.

In addition, in the catalyst temperature increase control, the temperature of the exhaust gas control catalyst 52 is directly increased by a reaction caused by the supply of the reducing agent to the exhaust gas control catalyst 52 and not by the increase in the temperature of the exhaust gas flowing into the exhaust gas control catalyst 52 when the engine 1 is cold started is carried out. Accordingly, the complicated control program is not required, and adjustment or coordination with the engine control or the like to stabilize the combustion of the internal combustion engine is also not required. Namely, the temperature of the exhaust gas control catalyst 52 can be increased by the control that is independent of the control of the engine body (for example, the main fuel injection control).

In the exemplary embodiment, the determination device of the partially activated state has that program which is processed in step S104 and the electronic control unit 22 , the exhaust gas temperature sensor 24 a for incoming gas and the exhaust gas temperature sensor 24 b for outgoing gas, which are required for processing the program , In addition, the catalyst temperature increasing device according to the invention has those programs which are processed in steps S104, S105, as well as the electronic control unit 22 and the reducing agent supply device 20 , which are required for processing the programs.

It should be noted that the routine described above only an example of the embodiment according to the Invention represents, and the details of which may vary Needs to be modified.

For example, in the example described above, the Process returns to the routine of step S104 and then sets the exhaust gas temperature again, namely the threshold of the partially activated state at step S108. The However, the process can go to the routine of step S104 return and then the temperature control of the incoming Perform gas to actively eliminate HC poisoning.

It should be noted that when controlling the temperature increase for incoming gas to eliminate HC poisoning to the above-mentioned air intake throttle control Secondary injection (post-injection) in the latter stage the combustion stroke of the internal combustion engine or during Exhaust stroke can be added. If also the process is repeated several times in step S108, then the Supply of the reducing agent to raise a temperature for be stopped for a predetermined period of time. In addition, the Temperature increase control of the incoming gas only then be performed when the process at step S108 is a predetermined number is repeated.

Furthermore, if the temperature increase control for incoming gas to eliminate HC poisoning at the step S108 is performed, various measures can then be taken such as for example, redefining the temperature setting are considered, which are set again at step S108 becomes.

In addition, if the temperature setting at step S104 is set again at step S108, then the value obtained after the setting again can be taken into account in the catalyst temperature control at the next starting period by the electronic control unit 22 learning the value after the redefinition is obtained.

In addition, with respect to the learning control, according to a study conducted by the inventors, it was confirmed that deterioration of the exhaust control catalytic converter occurs not infrequently when the temperature of the exhaust control catalytic converter 52 at which the exhaust control catalytic converter can be regarded as partially activated is increased. Accordingly, if the temperature of the exhaust gas at which the exhaust gas control catalyst can be considered partially activated is determined again (step S108), it is determined that the exhaust gas control catalyst 52 is deteriorated, and this determination result can be taken into account in the catalyst temperature increase control at the next start , In addition, the determination result may be taken into account by an amount of reducing agent that is supplied to raise a temperature of the exhaust gas control catalyst 52 , or the like.

In addition, in the example described above, it is determined that the exhaust control catalytic converter has reached the partially activated state if it is determined whether the exhaust control catalytic converter is in the partially activated state if the exhaust gas temperature at which the exhaust control catalytic converter can be considered partially activated is determined by both the exhaust gas temperature sensor 24 a for incoming gas and also detected by the exhaust gas temperature sensor 24 b for outgoing gas. However, this is not necessary. The supply of the reducing agent for increasing a temperature can be started after the exhaust gas temperature at which the exhaust gas control catalytic converter can be regarded as partially activated has been detected by one of the exhaust gas temperature sensors 24 a, 24 b.

In addition, a catalyst temperature sensor (for example, a thermocouple) that detects the temperature of the exhaust gas control catalyst 52 directly, are provided in the exhaust gas control catalyst 52 in addition to the exhaust gas temperature sensors 24 a 24 b, and the step S104 and the step S106 may on the basis of the temperature of the exhaust gas control catalyst 52 are processed, which is detected by the thermal coupler.

In addition, the control process can be configured as follows. The flow rate of the exhaust gas flowing into the exhaust control catalyst 52 is integrated after the engine is started and is recorded in the electronic control unit 22 (recorder). If it is determined that the exhaust gas control catalytic converter is in the partially activated state (step S104), then the exhaust gas temperature at which the exhaust gas control catalytic converter 52 can be regarded as partially activated is detected by the exhaust gas temperature sensor 24 a for incoming gas. In addition, if the integrated value of the flow rate of the exhaust gas recorded in the electronic control unit 22 has reached the flow rate at which the exhaust gas control catalytic converter 52 can be regarded as partially activated, then it is determined that the exhaust gas control catalytic converter has reached the partially activated state.

The flow rate of the exhaust gas can be converted from the intake air quantity, which is measured by an air flow measurement device 3 , which is provided in an intake system 2 of the internal combustion engine 1 . In this case, the electric control unit 22 converts the flow rate of the exhaust gas flowing into the exhaust gas control catalyst 52 to an integrated value of the intake air amount and records the integrated value after the engine starts.

That the integrated value of exhaust gas flow rate tends reference has whether the catalytic converter 52 is in the partially activated state in view of the fact apparent that the exhaust gas has a thermal energy, and the temperature of the exhaust gas control catalyst 52 is increased, since the exhaust gas in the exhaust catalyst 52 flows. Namely, "the integrated value of the exhaust gas flow rate" corresponds to the integrated value of the thermal energy of the exhaust gas, which is used for increasing the temperature of the exhaust gas control catalytic converter 52 .

In addition, in the determination at step S104, the time at which the exhaust gas control catalyst 52 can be regarded as partially activated, which is initially detected by one of the exhaust gas temperature sensors 24 a for incoming gas and the exhaust gas temperature sensor 24 b for outgoing gas, as the timing Starting the supply of the reducing agent can be considered.

In addition, if the temperature detected by the exhaust gas temperature sensor 24 a for incoming gas, the exhaust gas temperature sensor 24 b for outgoing gas and the catalyst temperature sensor continuously meets a temperature condition in which the exhaust gas control catalyst 52 is regarded as partially activated in a predetermined period of time in the determination in step S104 can then be considered as partially activated.

In addition, in the routine described above, the Timing for starting the supply of the reducing agent on the Determines the temperature of the exhaust gas. However, after the supply of the reducing agent for a determination before Supply of the reducing agent can be determined whether that Reducing agent for increasing the temperature is supplied.

That is, the determination of whether the exhaust gas control catalyst 52 is in the partially activated state based on the temperature of the exhaust gas is only an estimate. Therefore, the reducing agent is tentatively supplied before the start of the supply of the reducing agent for increasing a temperature, and it is actually confirmed that the temperature of the exhaust gas control catalyst is increased, after which it is determined whether the reducing agent is supplied for increasing a temperature.

In this case, if it is determined that the exhaust control catalyst is in the partially activated state at step S104, then the reducing agent is supplied for determination. Then, after the supply of the reducing agent, when the temperature of the exhaust gas control catalyst 52 , which increases due to the supply of the reducing agent, reaches or exceeds the predetermined temperature, the reducing agent is supplied to raise a temperature. In this case, it should be noted that the predetermined temperature is set based on the amount of reducing agent supplied at the determination time, the capacity of the catalytic converter 50, and the like. The predetermined temperature may be a value that is less than the exhaust gas temperature of 250 degrees Celsius, at which it is assumed that the exhaust gas control catalytic converter 52 has reached the activation temperature range. This is because an increase in the temperature of the exhaust gas control catalytic converter 52 due to the reducing agent for the determination must be confirmed. If the increase in temperature is confirmed, then it can be determined that the exhaust control catalyst is in the partially activated state.

In the example described above, when the reducing agent is supplied to raise a temperature, the reducing agent is also supplied at the predetermined amount and at predetermined intervals. However, this is not necessary. For example, the amount of reducing agent can be increased sequentially with each delivery, as shown in FIG. 5A. In addition, the frequency of the supply operation (valve opening operation) per unit time can be increased over time, as shown in FIG. 5B. HC poisoning must be avoided and the injection control can be modified as required.

Next, the activation determination device according to the invention will be described with reference to the flow chart shown in FIG. 6. The routine shown in FIG. 6 is a routine after a step S107. The exhaust control device 10 according to the embodiment accurately determines whether the exhaust control catalyst 52 has been activated by performing a routine as a series of the routines in addition to the routine described above.

A brief description of the procedure is as follows: The exhaust gas control device 10 detects the temperature of the exhaust gas flowing out of the exhaust gas control catalyst 52 after the previous catalyst temperature increase control has been performed. If the temperature of the exhaust gas reaches or exceeds the activation temperature range at which it can be assumed that the exhaust gas control catalytic converter has been activated due to the supply of the reducing agent, which is carried out together with the catalyst temperature increase control, then it is determined that the exhaust gas control catalytic converter is in the activated state.

The determination of whether the exhaust control catalyst 52 is in the activated state will be described with reference to the routine shown in FIG. 6.

First, the electronic control unit 22 sets the activation determination flag so as to determine whether the exhaust control catalyst 52 is in the activated state after the process at step S107 (step S201) is performed. Then, the electronic control unit 22 reads the output change of a load sensor (not shown) after the process at step S107 is performed, and determines the current operating state based on the output change (step S202).

In this case, the load sensor corresponds to the accelerator pedal when the internal combustion engine 1 according to the exemplary embodiment is used in a vehicle. The electronic control unit 22 determines that the current operating state is a steady state operation when the acceleration depression amount is constant, and the process proceeds to step S203 to determine whether the exhaust control catalyst 52 is in the activated state. Namely, in steady-state operation, an accurate determination can be made as to whether the exhaust gas control catalyst is in the activated state, since the temperature of the exhaust gas flowing into the exhaust gas control catalyst 52 is relatively stable.

In addition, at step S202, when the electronic control unit 22 detects the acceleration depression amount and determines that an acceleration operation is being performed, the accurate determination of whether the exhaust gas control catalyst is in the activated state cannot be made because the temperature of the exhaust gas control catalyst 52 flowing exhaust gas changes regardless of whether the exhaust control catalyst is activated. Accordingly, the routine returns.

Next, at step S203, when it is determined that the operating state is a steady state operation, the electronic control unit 22 starts reading the temperature of the exhaust gas downstream of the exhaust control catalyst 52 so as to measure the time of the temperature increase downstream of the exhaust control catalyst 52 , due to the supply of the reducing agent for increasing a temperature previously carried out.

If the read exhaust temperature is maintained at the exhaust temperature (250 degrees Celsius in the embodiment) at which the exhaust control catalyst can be considered activated for a predetermined period of time, then the electronic control unit 22 reliably determines that the exhaust control catalyst 52 is activated ( Step S204), and it determines that the exhaust control catalyst 52 is in the activated state (step S205).

In addition, if the exhaust gas temperature drops from 250 degrees Celsius before a predetermined period of time has passed in step S204, then it is determined that the exhaust control catalyst is still in the inactivated state. Accordingly, the process returns to step S104 so as to reactivate (to raise its temperature) the exhaust control catalyst 52 , and the electronic control unit 52 performs the processes in steps S201 to S204 to again determine whether the exhaust control catalyst 52 is in the activated state.

Note that the predetermined period of time, which is a threshold value of the activation determination, can be set as a fixed value in advance. However, the predetermined period of time, which is a reference for determination, can be calculated on a map prepared with the capacity of the exhaust gas control catalyst 52 and the amount of the reducing agent supplied in the period of controlling the catalyst temperature increase as a parameter. If the predetermined time period is set as the fixed value in advance, then it is preferable to ensure the average amount of the reducing agent that is supplied during the time period since the exhaust control catalyst is in the partially activated state until the exhaust control catalyst reaches the activation temperature range in which is tested in advance, and it is preferable to set the predetermined period of time to the average value.

Then, when it is determined that the exhaust control catalyst 52 is activated at step S204 (S205), the electronic control unit 22 starts supplying the reducing agent for cleaning so as to promote the exhaust control operation of the exhaust control catalyst 52 (step S206).

The supply of the reducing agent for cleaning is normally started after temperatures of the exhaust gas and the engine coolant have been raised sufficiently. However, in the embodiment, since it is determined whether the exhaust control catalyst 52 is activated by actually supplying the reducing agent when it is determined that the exhaust control catalyst is activated, the exhaust gas purification is performed even when the reducing agent is supplied regardless of the temperatures of the exhaust gas and the engine coolant.

Thus, in the routine, the supply of the reducing agent to raise a temperature of the exhaust control catalyst 52 is used as the supply of the reducing agent to determine whether the exhaust control catalyst is in the activated state, and then it is determined whether the exhaust control catalyst 52 is by the actual supply of the reducing agent is activated. That is, when it is necessary to determine whether the exhaust control catalyst is activated, it is determined whether the exhaust control catalyst 52 is activated by actually supplying the reducing agent. Accordingly, greater determination accuracy can be achieved than when determining whether the exhaust gas control catalyst 52 is in the activated state based on the estimation of the exhaust gas temperature.

In the routine, the temperature of the Exhaust gas exhausted from the engine body at step S202 indirectly recorded. However, this is a routine to ensure improving accuracy in determining whether the exhaust control catalytic converter is in the activated state. at the routine is determining whether the temperature of the Exhaust gas control catalyst reaches the temperature at which the Exhaust control catalytic converter can be regarded as activated, and by supplying the reducing agent together with the Control the increase in the previous catalyst temperature Reference to determine whether the exhaust control catalyst is in the activated state. Because if that Then catalyst temperature increase control is performed the temperature of the exhaust gas control catalytic converter becomes inevitable regardless of the temperature of the in the exhaust control catalyst flowing exhaust increases.

Accordingly, the activation of the exhaust gas control catalytic converter based on which it is determined whether the temperature has increased, then an exact determination is possible without the operating state of the engine body is impaired becomes.

It should be noted that the routine described above is only one embodiment, and the details can of course be modified.

For example, if the reducing agent is added, then the amount depending on the temperature of the Engine coolant can be increased. The reason for this is, that it can be assumed that the reducing agent on the Wall surface of the exhaust path is liable if, for example, the Engine coolant temperature is low and therefore the temperature of the exhaust system is also low. Moreover the amount of reducing agent is of course on the normal amount reset when the temperature of the Exhaust system that temperature of the engine coolant achieved at which the exhaust system warmed up as sufficient can be viewed.

In addition, an air / fuel ratio sensor is arranged downstream of the exhaust gas of the exhaust gas control catalyst 52 , and deterioration of the reducing agent supply nozzle, namely a determination of whether the predetermined amount of reducing agent is supplied correctly, is made based on the change in output from the air / fuel ratio sensor detected. If there is an error between the determined amount of the reducing agent supplied and the amount of the reducing agent actually supplied, the value when the reducing agent is supplied to raise a temperature can be reproduced.

The reason why the deterioration in Reductant supply nozzle in the period of supply of the Reductant for cleaning is that amount is larger than the amount of the reducing agent for increasing a temperature, and the error will likely be at the Output of the air / fuel ratio sensor reproduced.

In addition, the reason why the error in supplying the reducing agent to raise a temperature is reproduced is that more precise injection control is required compared to when the reducing agent is supplied for cleaning, because the reducing agent is supplied to raise a temperature, with the exhaust gas control catalyst 52 is partially activated.

In addition, regarding the exhaust system of the above-mentioned internal combustion engine 1 in the embodiment, the storage reduction NOx catalyst 52 a and the particulate filter 52 b are described as examples of the exhaust gas control catalyst 52 b according to the invention. However, the exhaust control catalyst according to the invention is not limited to this. The exhaust control catalyst according to the invention relates to the exhaust control catalyst in general, which is partially activated before being activated.

In the exemplary embodiment, the reducing agent supply valve 21 is provided in the exhaust gas duct 11 . However, the reducing agent supply valve of the invention may be provided on an exhaust port formed on the cylinder head, or in an exhaust passage upstream of the turbine housing 4 , etc.

As described above, according to the Embodiment a technique for increasing a temperature of the exhaust gas control catalytic converter, its temperature can be increased without the operating state of the Engine body is affected. In addition, a Techniques are provided that determine whether the Exhaust control catalytic converter is in the activated state without the operating state of the engine body is impaired becomes.

An exhaust control device determines whether an exhaust control catalyst is in is a partially activated state when a temperature of the exhaust gas control catalytic converter with regard to a Activation temperature range is low and the temperature must be increased, and it leads to a reducing agent Increase a temperature of the exhaust control catalyst when it is determined that the exhaust control catalyst in the partial activated state. In addition, the exhaust control device characterized in that a determination of whether the Exhaust control catalytic converter is activated, regardless of this is carried out whether the temperature of the exhaust gas control catalytic converter is increased by the supply of the reducing agent after that Reducing agent for increasing a temperature was supplied.

Claims (10)

1. exhaust gas control device for an internal combustion engine ( 1 ),
marked by
an exhaust gas control catalytic converter ( 52 ) which is attachable in an exhaust gas path of the internal combustion engine ( 1 ) and can purify an exhaust gas from the internal combustion engine when the temperature of the exhaust gas control catalytic converter is increased to an activation temperature range;
to promote a reducing agent supply means (20) for supplying a reducing agent to the exhaust gas control catalyst (52) to an exhaust gas control operation of the exhaust gas control catalyst (52);
catalyst temperature increasing means ( 22 ) for supplying a reducing agent to increase a temperature, the exhaust gas control catalyst ( 52 ) being partially activated, the supply being different from the supply of the reducing agent for promoting the exhaust gas control process, and for increasing a temperature of the exhaust control catalyst ( 52 ) a reaction of a catalytic substance carried by the exhaust control catalyst ( 52 ) and the supplied reducing agent; and
a partially activated condition determiner ( 22 ) for determining whether the exhaust control catalyst ( 52 ) is in a partially activated state,
wherein when the temperature of the exhaust gas control catalyst ( 52 ) is low in the activation temperature range and the temperature needs to be raised, a determination of whether the exhaust gas control catalyst ( 52 ) is in a partially activated state is made based on the partially activated state determining means , and if it is determined that the exhaust control catalyst ( 52 ) is in the partially activated state, then the reducing agent is supplied to raise a temperature. 2. The exhaust gas control device according to claim 1, further comprising:
a temperature sensor ( 24 b) for outgoing exhaust gas, which detects a temperature of the exhaust gas flowing out of the exhaust gas control catalytic converter ( 52 ); and
a temperature sensor ( 24 a) for incoming exhaust gas, which detects a temperature of the exhaust gas flowing into the exhaust gas control catalytic converter ( 52 ),
wherein the determining device ( 22 ) of the partially activated state determines that the exhaust gas control catalytic converter ( 52 ) is in the partially activated state if both the temperature sensor ( 24 b) for outgoing exhaust gas and the temperature sensor ( 24 a) for incoming exhaust gas detect an exhaust gas temperature , in which the exhaust control catalyst ( 52 ) is in the partially activated state. 3. The exhaust control device according to claim 1, further comprising:
A temperature sensor ( 24 a) for incoming exhaust gas, which detects a temperature of the exhaust gas flowing into the exhaust gas control catalytic converter ( 52 ); and
a recorder ( 3 , 22 ) that integrates and records an amount of exhaust gas flowing into the exhaust control catalyst ( 52 ) after the engine starts, the partially activated condition determining means ( 22 ) determining that the exhaust control catalyst ( 52 ) is in the partially activated state is when the temperature sensor ( 24 a) for incoming exhaust gas detects an exhaust gas temperature at which it can be assumed that the exhaust gas control catalytic converter ( 52 ) is in the partially activated state, and when an additional integrated value is recorded in the recording device ( 3 , 22 ) is recorded, a throughput rate is reached at which the exhaust gas control catalytic converter ( 52 ) is in the partially activated state. 4. Exhaust control device according to one of claims 1 to 3, further comprising:
an activation determination device ( 22 , 24 b) for determining whether the exhaust gas control catalyst ( 52 ) is in a state in which exhaust gas purification can be carried out based on a temperature of the exhaust gas flowing out of the exhaust gas control catalyst ( 52 ), the activation determination device ( 22 ) determines that the exhaust gas control catalytic converter ( 52 ) is in the state in which the exhaust gas purification can be carried out when the gas flowing out of the exhaust gas control catalytic converter ( 52 ) has reached or exceeded the activation temperature at which the exhaust gas control catalytic converter ( 52 ) is activated, due to the supply of the reducing agent for raising a temperature after the reducing agent has been supplied for raising a temperature. 5. The exhaust gas control device according to claim 4, wherein when it is determined in a determination made by the activation determination means ( 22 , 24 b) that the temperature of the exhaust gas flowing out of the exhaust gas control catalyst ( 52 ) has not reached an activation temperature range, the reducing agent for increasing a temperature is resupplied at the timing when the partial activation of the exhaust gas control catalyst ( 52 ) has advanced, and it is determined again whether the exhaust gas control catalyst ( 52 ) is in the state in which the exhaust gas purification can be performed. 6. The exhaust control device according to claim 5, wherein when the temperature of the exhaust gas flowing out of the exhaust control catalyst ( 52 ) has not reached the activation temperature range, a reference value in the determination by the determining means ( 22 ) of the partially activated state whether the exhaust control catalyst ( 52 ) is in partially activated state is greater than a previous value. 7. The exhaust control device according to any one of claims 1 to 5, wherein when the reducing agent is supplied through the reducing agent supply device ( 20 ), a predetermined amount of the reducing agent is supplied to the exhaust gas control catalyst ( 52 ) by performing a supply operation several times in each supply process, and if the reducing agent is supplied at the temperature increasing time, then the amount of reducing agent supplied in each supplying operation is reduced compared to the amount of reducing agent supplied when the exhaust gas control operation is promoted, and further the supplying operation per unit time is included in the temperature increasing time performed at a higher frequency than the supply process in that supply process when the exhaust control process is promoted. 8. The exhaust control device according to claim 7, wherein the at each The amount of reducing agent supplied sequentially is increased when the reducing agent in the Temperature increase time is supplied. 9. The exhaust control device according to claim 7, wherein the frequency of the Feed operation per unit of time increased over time when the reducing agent in the temperature increase time is fed. 10. Exhaust gas control method of an exhaust gas control catalytic converter, which can be attached to an internal combustion engine ( 1 ) and can clean exhaust gas from the internal combustion engine when a temperature of the exhaust gas control catalytic converter is increased to an activation temperature range, and a reducing agent supply device ( 20 ) for supplying a reducing agent to the exhaust gas control catalytic converter ( 52 ) to promote an exhaust control process of the exhaust control catalyst ( 52 ), and the exhaust control method is characterized by the following steps:
Determining that the exhaust control catalyst ( 52 ) is in the partially activated state when a temperature of the exhaust control catalyst ( 52 ) is low in the activation temperature range and the temperature needs to be raised, and
Supplying the reducing agent to raise a temperature of the exhaust control catalyst ( 52 ) when it is determined that the exhaust control catalyst ( 52 ) is in the partially activated state,
wherein the supply of the reducing agent to raise a temperature is different from a supply of the reducing agent to promote the exhaust control process and is performed when the exhaust control catalyst is in the partially activated state and the temperature of the exhaust control catalyst ( 52 ) is caused by a reaction between one catalytic substance carried by the exhaust gas control catalyst ( 52 ) and the supplied reducing agent is increased.