JP2010001779A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

The present invention relates to an exhaust emission control device for an internal combustion engine, and in the desorption operation for desorbing a specific component such as a component to be adsorbed from the adsorbent, the adsorbent is caused by the temperature drop of the exhaust gas caused by the desorption heat. It is an object to satisfactorily avoid a decrease in the purification capacity of the catalyst disposed on the downstream side of the catalyst.
An adsorbent is provided in a bypass passage that bypasses a main exhaust passage of an internal combustion engine and adsorbs specific components (HC, NOx) contained in the exhaust gas. A catalyst 18 that is disposed in the main exhaust passage 14 on the downstream side of the adsorbent 24 and can purify the exhaust gas is provided. The catalyst 18 is provided with a latent heat storage material 18a that undergoes phase transition in a specific purification temperature range in which the purification rate of the catalyst 18 is high. The latent heat capacity C _lat of the latent heat type heat storage material 18 a is set so that the total heat amount required for the phase transition is _{equal to} or greater than the total desorption heat amount C desorb when the specific component is desorbed from the adsorbent 24.
[Selection] Figure 2

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

  Conventionally, for example, Patent Document 1 discloses an exhaust gas purification apparatus for an internal combustion engine that includes, in a bypass passage branched from a main passage, a heat storage material that suppresses the temperature of exhaust gas, an adsorbent that traps exhaust hydrocarbons, and a catalyst with a heater. It is disclosed. In this conventional exhaust purification device, immediately after the start-up when the main catalyst arranged in the main passage is not yet activated, the switching valve is operated to guide the exhaust to the bypass passage, so that the adsorbent has hydrocarbons. Is adsorbed. Then, after the main catalyst is activated, when the catalyst with a heater reaches the activation temperature due to the heating by the heater, the switching valve is operated to guide the high-temperature exhaust to the bypass passage, so that the adsorbent Hydrocarbons are desorbed.

Japanese Patent Laid-Open No. 10-184346 Japanese Patent Laid-Open No. 5-79319 JP-A-5-59937 JP 11-125113 A

  By the way, when adsorption target components such as hydrocarbons and adsorption-inhibiting components such as moisture adsorbed on the adsorbent are desorbed from the adsorbent, the adsorbent passes through the adsorbent due to the influence of desorption heat associated with the desorption reaction As a result, the temperature of the exhaust gas is reduced. As a result, the temperature of the exhaust gas flowing into the catalyst disposed on the downstream side of the adsorbent decreases, so the temperature of the catalyst decreases, and the adsorption target component desorbed from the adsorbent It may be difficult to sufficiently purify the catalyst.

  The present invention has been made to solve the above-described problem, and during the desorption operation for desorbing a specific component such as a component to be adsorbed from the adsorbent, the temperature of the exhaust gas is reduced due to the heat of desorption. Thus, an object of the present invention is to provide an exhaust gas purification apparatus for an internal combustion engine that can satisfactorily avoid a decrease in the purification capacity of the catalyst disposed downstream of the adsorbent.

A first invention is an exhaust emission control device for an internal combustion engine,
An adsorbent disposed in the exhaust passage and adsorbing specific components contained in the exhaust gas;
A catalyst arranged in the exhaust passage downstream of the adsorbent and capable of purifying exhaust gas;
A latent heat storage material that is provided in the catalyst and causes a phase transition in a specific purification temperature range in which the purification rate of the catalyst is high;
The latent heat capacity of the latent heat type heat storage material is set such that the total amount of heat required for the phase transition is equal to or greater than the total amount of heat of desorption when the specific component is desorbed from the adsorbent. .

The second invention is the first invention, wherein
The exhaust passage branches from the main exhaust passage at an upstream connection portion between the main exhaust passage through which exhaust gas discharged from the internal combustion engine flows and the main exhaust passage, and is connected downstream from the upstream connection portion. A bypass passage that merges with the main exhaust passage again in the section,
The adsorbent is disposed in the bypass passage;
The catalyst including the latent heat type heat storage material is arranged in the main exhaust passage on the downstream side of the downstream connection portion.

The third invention is the first or second invention, wherein
The time required from the completion of desorption of the specific component from the adsorbent to the recovery of the adsorption performance of the adsorbent is shorter than the time required from the start to the end of the phase transition of the latent heat storage material. As described above, the cooling performance of the adsorbent is set.

Moreover, 4th invention is 1st or 2nd invention,
The time required from the completion of desorption of the unpurified components from the adsorbent to the recovery of the adsorption performance of the adsorbent is shorter than the time required from the start to the end of the phase transition of the latent heat storage material. As described above, the heat retention performance of the latent heat storage material is set.

According to a fifth invention, in any one of the second to fourth inventions,
A flow path switching means capable of switching an inflow destination of exhaust gas between the main exhaust passage and the bypass passage;
Temperature acquisition means for acquiring the temperature of the latent heat storage material;
A flow path control means for controlling the flow path switching means so that exhaust gas flows into the adsorbent when the temperature of the latent heat storage material is higher than the temperature at which the phase transition occurs;
Is further provided.

The sixth invention is the fifth invention, wherein
A temperature determination means for determining whether the temperature of the latent heat storage material reaches an inflection point at which the temperature of the latent heat storage material starts to increase after the phase transition is completed;
The flow path control means controls the flow path switching means so that exhaust gas flows into the adsorbent when it is determined that the temperature of the latent heat storage material has reached the inflection point. Features.

The seventh invention is an exhaust emission control device for an internal combustion engine,
An adsorbent disposed in the exhaust passage and adsorbing specific components contained in the exhaust gas;
A catalyst arranged in the exhaust passage downstream of the adsorbent and capable of purifying exhaust gas;
A latent heat storage material that is provided in the catalyst and causes phase transition in a specific purification temperature range in which the purification rate of the catalyst is high; and
An adsorption amount acquisition means for acquiring an adsorption amount of the specific component to the adsorbent;
A heat storage amount setting means for setting a necessary heat storage amount of the latent heat storage material based on the acquired adsorption amount;
It is characterized by providing.

The eighth invention is the seventh invention, wherein
The heat storage amount setting means sets the necessary heat storage amount so that the specific amount corresponding to the acquired adsorption amount becomes a heat amount satisfying a total desorption heat amount when desorbing from the adsorbent. Features.

The ninth invention is the seventh or eighth invention, wherein
The heat storage amount setting means includes
Input heat amount adjusting means for adjusting the input heat amount to the latent heat type heat storage material,
Heat storage amount acquisition means for acquiring the heat storage amount of the latent heat storage material,
The input heat amount adjusting means is
The amount of heat input to the latent heat storage material is adjusted based on the acquired adsorption amount and heat storage amount.

Also, a tenth invention is any one of the seventh to ninth inventions,
The input heat amount adjusting means is
A heat storage amount determination means for determining whether or not the necessary heat storage amount is stored in the latent heat storage material;
Execution of desorption operation for performing desorption operation for desorbing the specific component adsorbed on the adsorbent from the adsorbent when it is determined that the necessary heat storage amount is stored in the latent heat storage material Means,
Is further provided.

The eleventh aspect of the invention is the tenth aspect of the invention,
The exhaust passage branches from the main exhaust passage at an upstream connection portion between the main exhaust passage through which exhaust gas discharged from the internal combustion engine flows and the main exhaust passage, and is connected downstream from the upstream connection portion. A bypass passage that merges with the main exhaust passage again in the section,
The adsorbent is disposed in the bypass passage;
The catalyst including the latent heat storage material is disposed in the main exhaust passage on the downstream side of the downstream connection portion,
The exhaust emission control device further includes a flow path switching means capable of switching an inflow destination of exhaust gas between the main exhaust passage and the bypass passage,
The desorption operation executing means controls the flow path switching means so that the exhaust gas flows into the adsorbent when it is determined that the necessary heat storage amount is stored in the latent heat storage material. Means.

The twelfth invention is the tenth or eleventh invention,
The exhaust purification device further includes temperature acquisition means for acquiring temperatures of a plurality of portions in the flow direction of the exhaust gas in the latent heat storage material,
When the temperature of the latent heat storage material becomes higher than the temperature at which the phase transition occurs in the portion satisfying the necessary heat storage amount in the plurality of portions, the heat storage amount determination means is applied to the latent heat storage material. It is determined that the necessary heat storage amount is stored.

The thirteenth aspect of the invention is any one of the seventh to twelfth aspects of the invention.
The latent heat type heat storage material is divided into a plurality of parts in the exhaust gas flow direction, and is provided in the catalyst in a state of being insulated between the plurality of parts.

  According to the first invention, even when the temperature of the exhaust gas flowing into the catalyst is lowered due to the heat of desorption in the adsorbent during the adsorbent desorption operation, the purification rate of the catalyst is reduced. Since the latent heat storage material that undergoes a phase transition in a specific purification temperature range that is high stores heat of a latent heat capacity that is greater than the total desorption heat amount when the specific component is desorbed from the adsorbent, It can be avoided that the temperature is lower than the phase transition temperature of the latent heat storage material. Therefore, according to the present invention, when the adsorbent is desorbed, the purification ability of the catalyst disposed downstream of the adsorbent is reduced due to the temperature decrease of the exhaust gas caused by the desorption heat. Can be avoided well.

  According to the second invention, the adsorbent is provided in the bypass passage that bypasses the main exhaust passage, and in the main exhaust passage downstream of the downstream connection portion between the bypass passage and the main exhaust passage, In a configuration in which a catalyst including a latent heat storage material is provided, when performing the desorption operation of the adsorbent, it is preferable that the purification capacity of the catalyst is reduced due to a decrease in the temperature of the exhaust gas caused by the desorption heat Can be avoided.

  According to the third or fourth invention, during the vehicle soak, the temperature of the catalyst including the latent heat storage material is within the purification temperature range in which the purification rate is high until the adsorbent recovers the adsorption capacity. The temperature will be maintained. For this reason, the catalyst in which the activation temperature (or ignition temperature) is ensured in a situation where the adsorption capacity of the adsorbent is not sufficiently recovered because the adsorbent is not completely cooled due to the short vehicle soak time. Thus, the specific component that has not been adsorbed by the adsorbent can be purified. On the other hand, in a situation where the catalyst has cooled down due to a long vehicle soak time and the catalyst cannot exhibit a predetermined purification capacity, the above-mentioned specific component is absorbed by an adsorbent that is in a state where it can exhibit a sufficient adsorption capacity. It can be adsorbed and purified. Thus, according to the present invention, it is possible to effectively complement the exhaust emission reduction effect between the catalyst having the latent heat storage material and the adsorbent.

  According to the fifth aspect of the present invention, the catalyst maintained at a temperature at which sufficient purification ability is ensured even when the temperature of the exhaust gas decreases due to heat of desorption when the specific component is desorbed from the adsorbent. Thus, the specific component desorbed from the adsorbent can be reliably purified.

  According to the sixth invention, whether or not exhaust heat that can avoid the temperature decrease of the catalyst due to the temperature decrease of the exhaust gas accompanying the desorption of the specific component from the adsorbent is charged to the latent heat storage material, It becomes possible to grasp accurately without excess or deficiency. Thereby, the start timing of the desorption operation can be optimized (minimized).

  According to the seventh aspect, the necessary heat storage amount of the latent heat storage material can be appropriately set in accordance with the amount of desorption when a specific component is desorbed from the adsorbent.

  According to the eighth aspect of the invention, regardless of the amount of adsorption at the time of start-up, the purification capacity of the catalyst is reduced due to the temperature drop of the exhaust gas caused by the desorption heat when performing the desorption operation of the adsorbent. Can be avoided well.

  According to the ninth aspect, the necessary heat storage amount of the latent heat storage material can be appropriately set according to the amount of desorption when a specific component is desorbed from the adsorbent.

  According to the tenth aspect, the start timing of the desorption operation can be optimized (minimized) regardless of the amount of adsorption to the adsorbent at the time of startup.

  According to the eleventh invention, when it is determined that the necessary heat storage amount is stored in the latent heat storage material, the desorption operation is started by supplying the exhaust gas to the adsorbent. For this reason, the start timing of the desorption operation can be optimized (minimized) regardless of the amount of adsorption to the adsorbent at the start.

  According to the twelfth invention, based on the temperature information of each part of the latent heat type heat storage material, it is possible to accurately grasp the time when the necessary heat storage amount corresponding to the adsorption amount at the time of starting is stored in the latent heat type heat storage material. .

  According to the thirteenth aspect, since heat conduction between the plurality of parts of the latent heat storage material is interrupted, the amount of heat stored in each part can be grasped more accurately.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining a configuration of an internal combustion engine system including an exhaust purification device according to Embodiment 1 of the present invention. An internal combustion engine 10 shown in FIG. 1 includes an intake passage 12 for taking air into the cylinder and an exhaust passage through which exhaust gas discharged from the cylinder flows.

  The exhaust passage of the present embodiment includes a main exhaust passage 14 for discharging exhaust gas from the cylinder, and a bypass passage 20 described later. The main exhaust passage 14 has, in order from the upstream side, a front catalyst (S / C: Start Catalyst) 16 that can purify unpurified components (HC, NOx, CO, etc.) contained in the exhaust gas, and a latent heat of fusion type The rear catalyst (UF / C: Underfloor Catalyst) 18 provided with the heat storage material 18a is arranged in series.

  More specifically, the heat storage material 18a is embedded in the base material of the post-catalyst 18 in a lattice shape or a strip shape in a state of being isolated from the exhaust gas passage inside the catalyst. Further, as shown in FIG. 1, the latter catalyst 18 is covered with a heat insulating material 18b so as to be isolated from the surroundings. Since the configuration of the rear catalyst 18 including such a heat storage material 18a is a characteristic part of the present embodiment, it will be described in detail later. Hereinafter, the rear catalyst 18 including the heat storage material 18a may be abbreviated as “heat storage catalyst 18”.

  The system of this embodiment includes a bypass passage 20 as a passage that bypasses the main exhaust passage 14. The bypass passage 20 branches from the main exhaust passage 14 at the upstream connection portion 20a located downstream of the upstream catalyst 16, and again enters the main exhaust passage 14 at the downstream connection portion 20b located downstream of the upstream connection portion 20a. It is configured to merge. In addition, a switching valve (V1) 22 for switching the inflow destination of the exhaust gas between the main exhaust passage 14 and the bypass passage 20 is disposed in the upstream connection portion 20a.

  A function of adsorbing specific adsorption target components (HC, NOx) and moisture (components that inhibit adsorption of the adsorption target components to the adsorbent 24) contained in the exhaust gas is provided in the middle of the bypass passage 20. The adsorbent 24 which has is arrange | positioned. The adsorption capacity of the adsorbent 24 is set with a margin so that the adsorption target component and the adsorption-inhibiting component introduced into the adsorbent 24 at the start in the standard state can be adsorbed.

  As an adsorbent suitable for moisture and HC adsorption, for example, a zeolite-based material can be used, and as an adsorbent suitable for NOx adsorption, for example, a material in which iron Fe is supported on zeolite can be used. it can. Furthermore, as an adsorbent suitable for lower HC adsorption, for example, a material in which silver Ag is supported on ferrierite can be used.

  In addition, fins (heat dissipating members) 24 a for adjusting the cooling performance of the adsorbent 24 to a desired value are provided on the outer periphery of the casing that houses the adsorbent 24. Since the setting of the cooling performance of the adsorbent 24 is a characteristic part of the present embodiment, it will be described in detail later.

  A temperature sensor 26 for detecting the temperature of the exhaust gas flowing into the heat storage catalyst 18 is attached to the main exhaust passage 14 on the inlet side of the heat storage catalyst 18. Further, the heat storage catalyst 18 incorporates a temperature sensor 28 for detecting the temperature of the heat storage catalyst 18 (temperature of the heat storage material 18a).

  The system of this embodiment includes an ECU (Electronic Control Unit) 30. Various sensors for controlling the internal combustion engine 10 are connected to the ECU 30 together with the temperature sensors 26 and 28. Various actuators are connected to the ECU 30 together with the switching valve 22 described above.

  According to the system of the present embodiment configured as described above, the switching valve 22 is controlled so that the bypass passage 20 is closed (in the state “b” shown in FIG. 1) during the normal operation of the internal combustion engine 10. By doing so, the exhaust gas can flow as it is through the main exhaust passage 14 without passing through the bypass passage 20.

  Further, according to the system of the present embodiment, when the adsorption target component in the exhaust gas is adsorbed to the adsorbent 24 at the cold start, the main exhaust passage 14 is closed (“a” shown in FIG. 1). By controlling the switching valve 22), the entire exhaust gas discharged from the internal combustion engine 10 can be introduced into the adsorbent 24 of the bypass passage 20. As a result, the adsorption target component and moisture can be adsorbed and removed by the adsorbent 24, and the unpurified component (the adsorption target) contained in the exhaust gas can be removed during a cold start when the pre-stage catalyst 16 or the like has not yet been activated. (Component) can be prevented from being released into the atmosphere.

  Further, according to the system of the present embodiment, the switching valve 22 is set in FIG. 1 at a stage after the adsorption operation of the adsorbent 24 is completed and before the adsorption target component is desorbed from the adsorbent 24. By controlling to the "b" state shown, the heat of the exhaust gas warmed after the start can be stored in the heat storage material 18a included in the heat storage catalyst 18 (the timing at which the desorption operation (purge operation) can be performed) Wait for the purge wait period).

  Further, according to the system of the present embodiment, after the warm-up of the heat storage catalyst 18 is completed after the internal combustion engine 10 is started, the main exhaust passage 14 is closed (in the state “a” shown in FIG. 1). ) By controlling the switching valve 22, high-temperature exhaust gas is introduced into the adsorbent 24 to desorb components to be adsorbed and moisture from the adsorbent 24, and then desorbed using the active heat storage catalyst 18. The separated unpurified components can be purified.

  Further, according to the system of the present embodiment, after the desorption operation is completed, the switching valve 22 is controlled again to the “b” state shown in FIG. As a result, the adsorbent 24 in a high temperature state can be cooled, and the heat storage catalyst 18 can be charged with exhaust heat.

  By the way, as in the system of this embodiment, in a system including an adsorbent and a catalyst on the downstream side of the adsorbent, an adsorption target component (unpurified component) such as hydrocarbon adsorbed on the adsorbent, moisture, etc. When the adsorption-inhibiting component is desorbed from the adsorbent, the temperature of the exhaust gas that has passed through the adsorbent decreases due to the effect of desorption heat associated with the desorption reaction. As a result, the temperature of the exhaust gas flowing into the catalyst disposed on the downstream side of the adsorbent decreases, so the temperature of the catalyst decreases, and the adsorption target component desorbed from the adsorbent It may be difficult to sufficiently purify the catalyst.

[Characteristic configuration of heat storage material]
In the present embodiment, the purification of the post-catalyst 18 disposed downstream of the adsorbent 24 due to the temperature drop of the exhaust gas caused by the desorption heat during the desorption operation for desorbing the adsorption target component from the adsorbent 24. In order to avoid a decrease in capacity, the heat storage material 18a included in the rear catalyst 18 is configured as follows.

FIG. 2 is a view for explaining the configuration of the heat storage catalyst 18 including the heat storage material 18a shown in FIG. More specifically, FIG. 2 is a graph showing the relationship between the bed temperature of the heat storage catalyst 18 and the amount of heat released when the heat stored in the heat storage catalyst 18 is released with phase transition. It is.
As shown in FIG. 2, in this embodiment, the heat storage material 18 a is at a temperature higher than a temperature at which the heat storage catalyst 18 can secure a predetermined sufficient purification rate (a specific purification temperature at which the purification rate of the heat storage catalyst 18 becomes high). Range), the material or the like of the heat storage material 18a is selected and configured so that a phase transition between the solid phase and the liquid phase occurs.

Further, the latent heat storage capacity (hereinafter referred to as “latent heat capacity”) C _lat of the heat storage material 18a of the present embodiment is such that the total amount of heat required for the phase transition _varies from the adsorbent 24 to the specific component (the above-described adsorption target component (HC, NOx) or It is set to be _{equal to} or greater than the total desorption heat amount (≈ vaporization latent heat amount) _Cdesorb when the adsorption inhibiting component (water) is desorbed. The total desorption heat amount _Cdesorb is set based on the standard state.

According to such a setting, the temperature of the exhaust gas flowing into the heat storage catalyst 18 decreased due to the heat of desorption in the adsorbent 24 during the desorption operation for desorbing the adsorption target component from the adsorbent 24. Even in this case, the heat storage material 18a configured so that the phase transition occurs at a temperature higher than the temperature at which the heat storage catalyst 18 can secure a predetermined purification rate has a latent heat capacity C _{equal to} or greater than the total desorption heat amount _{Cdesorb. Since} the heat of _lat is stored, it can be avoided that the temperature of the heat storage catalyst 18 is lower than the phase transition temperature of the heat storage material 18a. Therefore, according to the configuration of the heat storage material 18a of the present embodiment, when performing the desorption operation of the adsorbent 24, the bed temperature of the rear catalyst 18 responsible for purifying the adsorption target component desorbed from the adsorbent 24 is activated. A high purification rate can be secured stably without lowering the temperature.

[Adsorption material cooling performance and heat storage material heat retention performance settings]
The adsorption capacity of the adsorbent 24 decreases as the temperature of the adsorbent 24 increases. For this reason, in the adsorbent 24 that is in a high temperature state due to the supply of the high-temperature exhaust gas during the desorption operation, the next adsorption operation is performed after the temperature of the adsorbent 24 is cooled below a predetermined temperature. It becomes possible. Therefore, when the internal combustion engine 10 is stopped under the condition that the adsorbent 24 is in a high temperature state due to the desorption operation, the internal combustion engine 10 is restarted after the internal combustion engine 10 stops. The shorter the time (vehicle soak time) is, the lower the temperature of the adsorbent 24 at the time of restarting, the more difficult it is to secure a sufficient adsorption capacity.

  In the present embodiment, the cooling performance of the adsorbent 24 and the heat retention performance of the heat storage material 18a are as follows in order to obtain a stable exhaust emission reduction effect at the time of restart regardless of the length of the vehicle soak time. It has features in the set points.

  FIG. 3 is a diagram for explaining the setting of the cooling performance of the adsorbent 24 and the heat retention performance of the heat storage material 18a according to Embodiment 1 of the present invention. More specifically, FIG. 3 shows a state where the adsorbent 24 is in a high temperature state due to the desorption operation, and the heat storage catalyst 18 is in a higher temperature state than the phase transition temperature of the heat storage material 18a. Represents vehicle soak time from

  As shown in FIG. 3, the adsorbent 24 at the time of vehicle soaking is radiated as the vehicle soak time elapses and the temperature is lowered. Accordingly, the adsorbing capacity of the adsorbent 24 is restored. A time t1 in FIG. 3 indicates a point in time when the adsorption capacity of the adsorbent 24 is restored to a level at which the exhaust emission at the start can be purified with a predetermined sufficient adsorption rate.

  On the other hand, as described above, the phase transition temperature of the heat storage material 18a is set to a temperature at which the purification rate of the heat storage catalyst 18 can be sufficiently secured. For this reason, as shown in FIG. 3, the heat storage catalyst 18 during vehicle soak does not change as sensible heat until the phase change starts and completes as the vehicle soak time elapses. The heat release proceeds in a state where a sufficient purification rate is secured, and then the temperature of the heat storage catalyst 18 decreases after the phase transition is completed. Time t2 in FIG. 3 indicates a time point when the purification capacity of the heat storage catalyst 18 falls below a level at which the exhaust emission at the start can be purified with a predetermined sufficient purification rate (a time point when the heat storage catalyst 18 falls below the activation temperature or ignition temperature). ing.

  In the present embodiment, as shown in FIG. 3, during the vehicle soak, the purification capacity of the heat storage catalyst 18 is accompanied by a phase transition rather than the time t1 required for the adsorption capacity of the adsorbent 24 to recover to a predetermined level. Thus, the cooling performance of the adsorbent 24 and the heat retention performance of the heat storage material 18a are set so that the time t2 during which the predetermined level can be maintained (the time during which the heat storage catalyst 18 can maintain the activation temperature or the ignition temperature) becomes longer. In other words, the time required to recover the adsorption performance of the adsorbent 24 after the completion of desorption of the unpurified components from the adsorbent 24 is longer than the time required from the start to the end of the phase transition of the latent heat storage material 18a. Also, the cooling performance of the adsorbent 24 and the heat retaining performance of the heat storage material 18a are set so as to be shorter.

The cooling performance on the side of the adsorbent 24 to satisfy the above relationship (t1 <t2) can be set by selecting the shape, material, etc. of the fin (heat radiating member) 24a. Further, the heat retention performance on the heat storage catalyst 18 side for satisfying the above relationship (t1 <t2) is adjusted by adjusting the heat insulation effect by selecting the material and the amount of use of the heat insulating material 18b, and the latent heat capacity C _lat of the heat storage material 18a. It is possible by adjusting.

  According to the setting shown in FIG. 3, the temperature of the heat storage catalyst 18 is maintained at a temperature within a range in which a predetermined purification rate can be ensured until the adsorbent 24 recovers the adsorption capacity during vehicle soaking. It becomes like this. For this reason, the active temperature (or ignition temperature) is ensured in the situation where the adsorption capacity of the adsorbent 24 is not sufficiently recovered because the adsorbent 24 is not completely cooled due to the short vehicle soak time. The adsorption target component that has not been adsorbed by the adsorbent 24 can be purified by the heat storage catalyst 18.

  On the other hand, in a situation where the heat storage catalyst 18 cannot cool because the heat storage catalyst 18 has cooled down due to a long vehicle soak time, the adsorbent 24 is in a state where it can exhibit a sufficient adsorption capacity. The adsorption target component can be adsorbed and purified. Thus, according to the setting of the present embodiment, it is possible to effectively complement the effect of reducing exhaust emission between the adsorbent 24 and the heat storage catalyst 18.

[Method for determining start timing of desorption]
FIG. 4 is a diagram for explaining a characteristic determination method of the start timing of the desorption operation according to Embodiment 1 of the present invention. More specifically, FIG. 4 is a diagram showing the change in the bed temperature of the heat storage catalyst 18 when the heat storage catalyst 18 is charged with exhaust heat after the adsorption operation is completed, in relation to the amount of exhaust heat charge. .

  As shown in FIG. 4, when exhaust heat is charged to the heat storage catalyst 18 in a state where the heat storage material 18a is in a solid state, the bed temperature of the heat storage catalyst 18 is reduced from that of the heat storage material 18a from solid to liquid. It gradually increases until the phase transition starts. From the start of the phase transition of the heat storage material 18a to the completion thereof, the sensible heat of the heat storage catalyst 18 does not change, and the bed temperature of the heat storage catalyst 18 shows a constant value. And after the phase transition of the heat storage material 18a is completed (liquefaction is completed), the bed temperature of the heat storage catalyst 18 rises again.

  Therefore, in the present embodiment, when the temperature of the heat storage catalyst 18 is higher than the temperature at which the phase transition of the heat storage material 18a occurs based on the temperature of the heat storage catalyst 18 (heat storage material 18a) detected by the temperature sensor 28, the adsorbent. The high temperature exhaust gas was supplied to 24 to perform the desorption operation. More specifically, in this embodiment, the temperature of the heat storage catalyst 18 begins to rise after the phase transition of the heat storage material 18a from the solid phase to the liquid phase is completed (FIG. 4). Reference) was determined. Then, at a timing when it is determined that the temperature of the heat storage catalyst 18 has reached the inflection point, high-temperature exhaust gas is supplied to the adsorbent 24 (that is, the desorption operation is started).

As described above, the heat storage material 18a is configured such that the phase transition occurs at a temperature higher than the temperature at which the heat storage catalyst 18 can secure a predetermined purification rate, and the phase transition from the solid phase to the liquid phase is completed. The subsequent heat storage material 18a stores heat having a latent heat capacity C _{lat equal to} or greater than the above desorption heat amount _Cdesorb . For this reason, when the temperature of the heat storage catalyst 18 (heat storage material 18a) is higher than the temperature at which the phase transition occurs, the desorption operation is started, so that the adsorption target component and the like are desorbed from the adsorbent 24. Even if the temperature of the exhaust gas decreases due to the heat of desorption on the heat absorption side (cooling side), the adsorption target desorbed from the adsorbent 24 by the heat storage catalyst 18 maintained at a temperature at which a sufficient purification rate is secured. Ingredients can be reliably purified.

  In particular, in the present embodiment, the temperature of the heat storage catalyst 18 (heat storage material 18a) is an inflection point where the temperature of the heat storage catalyst 18 starts to rise after the phase transition of the heat storage material 18a from the solid phase to the liquid phase is completed ( The detachment operation is started at the timing when it is determined that it has reached (see FIG. 4). Since the stop timing of the internal combustion engine 10 is performed at an arbitrary timing by the driver of the vehicle, in order to surely perform the adsorption operation at the next start, the adsorbent 24 from which the adsorption operation has been completed is early. It is preferable to desorb components to be adsorbed. According to the start timing of the desorption operation, the heat storage material 18a is charged with exhaust heat sufficient to avoid the temperature decrease of the heat storage catalyst 18 due to the temperature decrease of the exhaust gas accompanying the desorption of the components to be adsorbed from the adsorbent 24. It becomes possible to accurately grasp whether or not it has been. Thereby, the start timing of the desorption operation can be optimized (minimized).

In the first embodiment described above, the rear catalyst (heat storage catalyst 18) corresponds to the “catalyst” in the first invention.
The switching valve 22 corresponds to the “flow path switching means” in the fifth invention, the temperature sensor 28 corresponds to the “temperature acquisition means” in the fifth invention, and the ECU 30 corresponds to the temperature sensor 28. By controlling the switching valve 22 based on the output, the “flow path control means” in the fifth aspect of the present invention is realized.
The ECU 30 determines the inflection point of the temperature of the heat storage catalyst 18 based on the output of the temperature sensor 28, thereby realizing the “temperature determination means” in the sixth aspect of the invention.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG.
[System Configuration of Embodiment 2]
FIG. 5 is a diagram for explaining the configuration of an internal combustion engine system including an exhaust purification device according to Embodiment 2 of the present invention. In FIG. 5, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As shown in FIG. 5, also in the present embodiment, a first bypass passage 42 similar to the bypass passage 20 of the first embodiment is provided as a passage that bypasses the main exhaust passage 40 on the downstream side of the front catalyst 16. Yes. The first bypass passage 42 is provided with the adsorbent 24, and the first upstream connection portion 42a of the first bypass passage 42 is connected to the main exhaust passage 40 and the first exhaust passage 40a. A first switching valve (V1) 44 for switching between the bypass passage 42 and the bypass passage 42 is disposed.

  Also in this embodiment, a downstream catalyst (heat storage catalyst) 46 including a latent heat type heat storage material 46a is provided in the main exhaust passage 40 downstream of the first downstream connection portion 42b of the first bypass passage 42. Is arranged.

  Furthermore, in the present embodiment, a second bypass passage 48 is provided as another passage that bypasses the main exhaust passage 40. The second bypass passage 48 branches from the main exhaust passage 40 at a second upstream connection portion 48a located downstream of the front catalyst 16 and upstream of the first upstream connection portion 42a, and the second upstream connection portion. The second downstream connection portion 48b located downstream of 48a and upstream of the first upstream connection portion 42a is configured to merge with the main exhaust passage 40 again. A second switching valve (V2) 50 for switching the inflow destination of the exhaust gas between the main exhaust passage 40 and the second bypass passage 48 is disposed in the second downstream side connection portion 48b.

  Furthermore, in this embodiment, as shown in FIG. 5, a heat exchanger 52 having a function of performing heat exchange between the heat storage catalyst 46 and the second bypass passage 48 is provided. The heat exchanger 52 is configured to cover the heat storage catalyst 46 and the second bypass passage 48 from the outside. The heat insulating material 54 of this embodiment is attached so as to cover the heat exchanger 52. Further, similarly to the heat storage catalyst 18 of the first embodiment, the heat storage catalyst 46 is also covered with the heat insulating material 54 so as to be isolated from the surroundings.

  According to the system of the present embodiment configured as described above, when performing the adsorption operation and the desorption operation, further, after the adsorption operation is completed and before the start of the desorption operation, When performing the exhaust heat charge operation, the exhaust gas path is divided between a path passing through the second bypass passage 48 having a heat exchange function with the heat storage catalyst 18 and a path not passing through the second bypass passage 48. It becomes possible to switch arbitrarily. Thereby, the outstanding effect which is demonstrated below can be show | played.

That is, first, the case of performing the suction operation will be described.
When the heat storage catalyst 18 and the heat exchanger 52 are relatively cold during the adsorption operation (when there is a sufficient period between the stop of the internal combustion engine 10 and the next start), the first By controlling the 2 switching valve 50 to the “b” state shown in FIG. 5, the exhaust gas can be supplied to the adsorbent 24 after being cooled by the heat exchanger 52. Thereby, the adsorption efficiency of the adsorbent 24 can be increased.

  On the other hand, when the heat storage catalyst 18 and the heat exchanger 52 are relatively hot during the adsorption operation (when the time from the stop of the internal combustion engine 10 to the next start is short), the second By controlling the switching valve 50 to the “a” state shown in FIG. 5, it is possible to prevent the gas traveling toward the adsorbent 24 from being heated through the heat exchanger 52. As described above, according to the configuration of the present embodiment, the temperature of the exhaust gas supplied to the adsorbent 24 during the adsorption operation can be optimized.

Next, a description will be given of when performing the desorption operation.
When performing the desorption operation, if it is determined that the temperature of the exhaust gas is relatively high, the exhaust gas is removed from the heat exchanger by controlling the second switching valve 50 to the “b” state shown in FIG. After being cooled by 52, it can be supplied to the adsorbent 24.

  On the other hand, when performing the desorption operation, if it is determined that the temperature of the exhaust gas is relatively low, the adsorbent 24 is controlled by controlling the second switching valve 50 to the “a” state shown in FIG. It is possible to avoid that the gas to be cooled is cooled through the heat exchanger 52. Thus, according to the configuration of the present embodiment, it is possible to satisfactorily stabilize the temperature of the exhaust gas input to the adsorbent 24 during the desorption operation.

Next, a description will be given of the case where the exhaust heat charging operation to the heat storage catalyst 18 is performed after the adsorption operation is completed and before the desorption operation is started.
In the configuration shown in FIG. 5, the second switching valve 50 is provided not in the second upstream connection portion 48a but in the second downstream connection portion 48b. When performing the exhaust heat charging operation, the second switching valve 50 is controlled to the “b” state shown in FIG. 5 (in this case, the first switching valve 44 is “b” shown in FIG. 5). Control to the state).

  According to such an exhaust heat charging operation, the exhaust gas flowing in the upstream portion of the switching valves 50 and 44, that is, the heat of the higher-temperature exhaust gas before heat loss occurs in the switching valves 50 and 44, The heat storage catalyst 46 can be supplied via the heat exchanger 52. For this reason, the charge rate of the exhaust heat to the heat storage catalyst 46 can be improved satisfactorily, and the activity of the heat storage catalyst 46 can be accelerated well. As a result, it is possible to favorably shorten the time required from the completion of the adsorption operation to the start of the desorption operation.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS.
[System Configuration of Embodiment 3]
FIG. 6 is a diagram for illustrating a configuration of an internal combustion engine system including an exhaust purification device according to Embodiment 3 of the present invention. In FIG. 6, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  The system of the present embodiment is configured in the same manner as the system of the first embodiment described above, except that the configuration of the latent latent heat type heat storage material 60a included in the rear catalyst (heat storage catalyst) 60 is different. More specifically, as shown in FIG. 6, the heat storage material 60a of this embodiment is divided into three parts in a direction orthogonal to the flow direction of the exhaust gas.

  Moreover, as shown in FIG. 6, between each site | part of the three divided | segmented thermal storage material 60a, and between the back | latter stage catalyst 60 provided with the thermal storage material 60a, and circumference | surroundings, with the thermal insulation material 60b similar to the said thermal insulation material 18b. Each is partitioned.

Further, the total latent heat capacity of the heat storage material 60a divided into three is set to be equal to the latent heat capacity of the heat storage material 18a of the first embodiment described above. That is, the total amount of heat required for the phase transition of the heat storage material 60a is equal to the total amount of heat released when the specific component is adsorbed when the specific component with the full adsorption capacity is adsorbed on the adsorbent 24 (≈ vaporization). The total amount of latent heat capacity of the three parts of the heat storage material 60a is set so as to be _{equal to} or greater than (latent heat amount) _Cdesorb .

  Furthermore, temperature sensors 62, 64, and 66 for detecting the temperature of the heat storage catalyst 60 at each portion (the temperature of the heat storage material 60a) are incorporated in each portion of the heat storage material 60a divided into three parts. ing. These temperature sensors 62, 64, 66 are all connected to the ECU 68 of the present embodiment.

[Control of Embodiment 3]
By the way, depending on the starting condition of the internal combustion engine 10, the adsorption amount of the specific component adsorbed on the adsorbent 24 during the adsorption operation at the time of start varies. More specifically, the higher the temperature of the pre-stage catalyst 16 at the time of starting, the shorter the time required until the pre-stage catalyst 16 is activated, so that the amount of adsorption of the specific component adsorbed on the adsorbent 24 is reduced. Less.

As described above, in the situation where only the specific component in an amount smaller than the adsorption capacity of the adsorbent 24 is adsorbed, the specific capacity of the adsorbent 24 full of the adsorbing capacity is obtained as in the first embodiment. It can be said that it is not necessary to delay the start of the desorption operation until the heat storage material 60a is charged with a heat amount _{equal to} or greater than the total desorption heat amount _Cdesorb when the component is desorbed from the adsorbent 24.

  Therefore, in the present embodiment, based on the adsorption amount of the adsorbent 24 at the start of this time, the necessary heat storage amount that should be charged to the heat storage material 60a to prevent the temperature decrease of the heat storage catalyst 60 during the desorption operation is determined. I set it.

  For this purpose, the amount of heat input to the heat storage material 60a is adjusted based on the amount of adsorption of the adsorbent 24 and the heat storage amount charged in the heat storage material 60a. More specifically, when the amount of heat equal to or greater than the amount of heat of desorption when the specific component corresponding to the amount of adsorption of the adsorbent 24 at the time of starting this time is desorbed from the adsorbent 24 is stored in the heat storage material 60a, The heat storage material 60a for overcoming the temperature drop of the heat storage catalyst 60 during the desorption operation is terminated (the purge operation standby period is terminated) and the desorption operation of the adsorbent 24 is started.

FIG. 7 is a flowchart of a routine executed by the ECU 68 in the third embodiment in order to realize the above function. Note that this routine is started when the adsorption operation of the adsorbent 24 at the start is completed.
In the routine shown in FIG. 7, first, thermal charge to the heat storage catalyst 60 is started (step 100). Specifically, in step 100, upon completion of the adsorption operation at the start, the switching valve 22 is controlled to the “b” state shown in FIG. Further, the execution of the purge operation is suspended until the necessary heat storage amount is stored in the heat storage material 60a thereafter (purge standby period).

Next, the heat charge amount (heat storage amount) of the heat storage catalyst 60 (heat storage material 60a) is estimated (step 102).
FIG. 8 is a time chart showing a temperature change in each part of the heat storage catalyst 60 during the purge standby period.
When the heat storage catalyst 60 is thermally charged, the input exhaust heat is charged sequentially from the upstream portion of the heat storage material 60a divided into three. Therefore, the phase transition is completed earliest at the most upstream portion of the heat storage material 60a, and a temperature inflection point appears at the temperature Tcat1 as shown in FIG.

  Thereafter, the exhaust heat input is charged in the central portion of the heat storage material 60a divided into three, and when the phase transition in the central portion is completed, as shown in FIG. 8B, the temperature Tcat2 is also increased. A temperature inflection point will appear. Similarly, after the exhaust heat input is charged in the most downstream portion of the heat storage material 60a and the phase transition in the most downstream portion is completed, as shown in FIG. A temperature inflection point also appears in Tcat3.

  Therefore, the heat charge amount (heat storage amount) of the heat storage material 60a is obtained by arbitrarily acquiring the temperature of each part and the temperature inflection points of Tcat1 to Tcat1-3 based on the output changes of the temperature sensors 62, 64, 66. Can be estimated.

FIG. 9 is a diagram showing the relationship between the heat storage amount of the heat storage material 60a and the estimated input heat amount. The estimated amount of heat input to the heat storage material 60a can be estimated based on the exhaust gas temperature at the inlet of the heat storage catalyst 60, for example.
As shown in FIG. 9, as the amount of heat input to the heat storage material 60a increases, the heat storage amount of the heat storage material 60a increases.

  Therefore, instead of estimating the heat storage amount based on the temperature inflection point described with reference to FIG. 8, the relationship between the heat storage amount and the estimated input heat amount shown in FIG. 9 is stored in advance in the ECU 68 as a map or a relational expression. In this step 102, after calculating the estimated input heat amount based on the exhaust gas temperature at the inlet of the heat storage catalyst 60 detected by the temperature sensor 26, the heat storage amount of the heat storage material 60a is obtained from such a map or the like. It may be.

  According to the estimation method of the heat storage amount based on the temperature inflection point described with reference to FIG. 8, the heat storage amount can be accurately estimated based on the temperature inflection point information. However, the estimated heat storage amount is discontinuous because it is determined that each temperature inflection point has been reached. On the other hand, according to the estimation method shown in FIG. 9, the heat storage amount can be continuously estimated based on the change in the estimated input heat amount at the time of heat charging.

  Furthermore, as shown in FIG. 9, the temperature inflection point information of each part of the heat storage material 60a may be added to the relationship between the heat storage amount stored in advance in the ECU 68 and the estimated input heat amount. According to such an estimation method, the heat storage amount can be continuously estimated with high accuracy by using the estimated input heat amount and the temperature inflection point information at the time of heat charging.

  In the routine shown in FIG. 7, the processes in steps 104 to 108 are executed in parallel with the processes in steps 100 and 102. Specifically, first, in step 104, the amount of adsorption of the adsorbent 24 when the internal combustion engine 10 is started this time is estimated (step 104).

  As described above, the higher the temperature of the engine coolant at start-up and the temperature of the front catalyst 16, the faster the activation of the front catalyst 16. Therefore, the adsorption amount of the adsorbent 24 can be estimated based on the engine coolant temperature at the time of starting and the temperature of the pre-stage catalyst 16. The engine coolant temperature can be acquired based on the output of a water temperature sensor (not shown), and the temperature of the front catalyst 16 may be directly sensed by a temperature sensor or estimated from the engine coolant temperature or the like. May be.

  Next, the amount of heat of desorption during the purge operation with the amount of adsorption estimated in step 104 is estimated (step 106). The amount of adsorption and the amount of heat of desorption during the purge operation are in a proportional relationship that the amount of heat of desorption increases as the amount of adsorption increases. For this reason, the relationship between the adsorption amount and the desorption heat amount during the purge operation is stored in the ECU 68 in advance, so that the desorption heat amount corresponding to the adsorption amount at the start of this time is calculated based on the estimated value of the adsorption amount. Can be estimated.

  Next, the estimated value of the heat of desorption acquired in step 106 is stored in a memory in the ECU 68 (step 108). The estimated heat of desorption stored in this step is used in the next step 110.

  In the routine shown in FIG. 7, after the process of step 102 is executed, the amount of heat charge (heat storage amount) of the heat storage catalyst 60 acquired in step 102 is the estimated desorption heat amount acquired in step 106. It is determined whether or not the above has been reached (step 110).

  As a result, if the determination in step 110 is not established, that is, if it can be determined that the current heat charge amount of the heat storage catalyst 60 is still insufficient in relation to the estimated desorption heat amount, the heat storage catalyst 60 is returned to. The heat charge (injection of exhaust heat) is continuously executed.

  On the other hand, if the determination in step 110 is satisfied, that is, if it can be determined that the heat storage catalyst 60 has been charged with a heat storage amount that can withstand the desorption heat amount corresponding to the adsorption amount at the time of the current start, the process proceeds to the heat storage catalyst 60. It is determined that it is time to end the thermal charge (step 112). In other words, it is determined that it is time to end the purge operation standby period.

  Therefore, in this case, a purge operation (desorption operation) of the adsorbent 24 is started (step 114). More specifically, when the switching valve 22 is controlled to the “b” state shown in FIG. 6, high-temperature exhaust gas is introduced into the adsorbent 24.

  Thereafter, when it is determined that the desorption of the specific component from the adsorbent 24 is completed, the purge operation of the adsorbent 24 is completed (step 116), and the memory value in step 108 is reset. . More specifically, the supply of the exhaust gas to the adsorbent 24 is stopped by controlling the switching valve 22 again to the “a” state shown in FIG. 6.

  According to the routine shown in FIG. 7 described above, the amount of heat input to the heat storage material 60a is adjusted based on the amount of adsorption of the adsorbent 24 and the amount of heat stored in the heat storage material 60a at the time of the current start. Become. More specifically, the purge operation of the adsorbent 24 starts when the heat storage material 60a stores a heat quantity equal to or greater than the estimated desorption heat quantity corresponding to the adsorption quantity at the start of this time. That is, according to the above routine, even when the amount of adsorption at the time of starting is smaller than the standard state due to the influence of the starting condition of the internal combustion engine 10, the heat storage capacity of the heat storage material 60a is stored to the full capacity. The purge operation is started when the necessary heat storage amount is input to the heat storage material 60a without waiting. Thereby, regardless of the amount of adsorption to the adsorbent 24 at the time of starting, the time (purge standby period) required from the completion of the adsorption operation to the start of the purge operation can be optimized (minimized) That is, the start timing of the purge operation can be optimized (minimized).

  In other words, according to the above routine, when the heat storage material 60a stores a heat amount equal to or larger than the estimated desorption heat amount corresponding to the adsorption amount at the start of this time, the heat storage material 60a has exhaust heat before the purge operation. The operation of putting in is terminated. That is, according to the above routine, the necessary heat storage amount to be charged in the heat storage material 60a is appropriately set based on the adsorption amount at the time of starting to prevent the temperature decrease of the heat storage catalyst 60 during the desorption operation. It becomes possible to leave. Accordingly, the heat storage amount of the heat storage material 60a can be appropriately set according to the amount of desorption when the specific component is desorbed from the adsorbent 24.

  By the way, in the first embodiment described above, the purge operation of the adsorbent 24 is started when the heat storage material 60a stores a heat quantity equal to or greater than the estimated desorption heat quantity corresponding to the adsorption quantity at the time of the current start-up. ing. However, in the present invention, the input heat amount adjustment means for adjusting the amount of heat input to the latent heat storage material based on the acquired adsorption amount and heat storage amount is not limited to that realized by such a method. That is, for example, when the amount of heat equal to or greater than the estimated amount of desorption heat corresponding to the amount of adsorption at the start of this time is stored in the heat storage material 60a, the input of the exhaust heat to the heat storage material 60a is stopped and other means ( For example, it may be switched so that exhaust heat is input to a catalyst disposed on a passage that bypasses the heat storage catalyst 60.

  Moreover, in Embodiment 1 mentioned above, it is made to provide the thermal storage material 60a divided into three so that it might partition with the heat insulating material 60b. Thereby, since the heat conduction between each site | part is interrupted | blocked, the heat storage amount of each site | part can be grasped | ascertained more correctly. However, in order to acquire the temperature inflection point of each site | part of the heat storage material 60a as shown in FIG. 8, the latent-heat type heat storage material of this invention does not necessarily need to be divided | segmented like the heat storage material 60a. Specifically, as in Embodiment 3 described above, the temperature of each part of the heat storage material is acquired at multiple points, and the amount of heat storage at the time of completion of the phase transition at each temperature acquisition position What is necessary is just to memorize | store the relationship with temperature acquisition position information in ECU68 previously.

In the third embodiment described above, the ECU 68 executes the process of step 104, so that the “adsorption amount acquisition means” in the seventh invention executes the processes of steps 100 to 114. The “heat storage amount setting means” in the seventh aspect of the invention is realized.
Further, when the ECU 68 executes the processing of the above steps 110 and 112, the “input heat amount adjusting means” in the ninth aspect of the invention executes the processing of the above step 102, thereby “the amount of stored heat” in the ninth aspect of the invention. "Acquisition means" is realized respectively.
Further, when the ECU 68 executes the process of step 110, the “heat storage amount determining means” in the tenth aspect of the invention executes the process of step 114, thereby executing “desorption operation execution” in the tenth aspect of the invention. Each means is realized.
Further, the “flow path control means” in the eleventh aspect of the present invention is realized by the ECU 68 executing the process of step 114.
The temperature sensors 62, 64, 66 correspond to the “temperature acquisition means” in the twelfth aspect of the invention.

It is a figure for demonstrating the structure of an internal combustion engine system provided with the exhaust gas purification apparatus in Embodiment 1 of this invention. It is a figure for demonstrating the structure of a thermal storage catalyst provided with the thermal storage material shown in FIG. It is a figure for demonstrating the setting of the cooling performance of the adsorbent, and the heat retention performance of a thermal storage material in Embodiment 1 of this invention. It is a figure for demonstrating the characteristic determination method of the start timing of the detachment | desorption operation | movement in Embodiment 1 of this invention. It is a figure for demonstrating the structure of an internal combustion engine system provided with the exhaust gas purification apparatus in Embodiment 2 of this invention. It is a figure for demonstrating the structure of an internal combustion engine system provided with the exhaust gas purification apparatus in Embodiment 3 of this invention. It is a flowchart of the routine performed in Embodiment 3 of the present invention. It is a time chart showing the temperature change in each part of the heat storage catalyst during the purge standby period. It is a figure showing the relationship between the heat storage amount of a heat storage material, and the estimated input heat amount.

Explanation of symbols

10 Internal combustion engine 14, 40 Main exhaust passage 16 Pre-stage catalyst 18, 46, 60 Post-stage catalyst (heat storage catalyst)
18a, 46a, 60a Melting latent heat storage material 18b, 54, 60b Thermal insulation material 20 Bypass passage 20a Upstream connection portion 20b Downstream connection portion 22 Switching valve 24 Adsorbent materials 26, 28, 62, 64, 66 Temperature sensors 30, 68 ECU (Electronic Control Unit)
42 1st bypass passage 42a 1st upstream connection part 42b 1st downstream connection part 44 1st switching valve 48 2nd bypass passage 48a 2nd upstream connection part 48b 2nd downstream connection part 50 2nd switching valve 52 Heat Exchanger C _desorp total heat of desorption C _lat latent heat capacity

Claims (13)

An adsorbent disposed in the exhaust passage and adsorbing specific components contained in the exhaust gas;
A catalyst arranged in the exhaust passage downstream of the adsorbent and capable of purifying exhaust gas;
A latent heat storage material that is provided in the catalyst and causes a phase transition in a specific purification temperature range in which the purification rate of the catalyst is high;
The latent heat capacity of the latent heat type heat storage material is set such that the total amount of heat required for the phase transition is equal to or greater than the total amount of heat of desorption when the specific component is desorbed from the adsorbent. An exhaust purification device for an internal combustion engine. The exhaust passage branches from the main exhaust passage at an upstream connection portion between the main exhaust passage through which exhaust gas discharged from the internal combustion engine flows and the main exhaust passage, and is connected downstream from the upstream connection portion. A bypass passage that merges with the main exhaust passage again in the section,
The adsorbent is disposed in the bypass passage;
2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the catalyst including the latent heat type heat storage material is disposed in the main exhaust passage downstream of the downstream connection portion.   The time required from the completion of desorption of the specific component from the adsorbent to the recovery of the adsorption performance of the adsorbent is shorter than the time required from the start to the end of the phase transition of the latent heat storage material. The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2, wherein the cooling performance of the adsorbent is set.   The time required from the completion of desorption of the unpurified components from the adsorbent to the recovery of the adsorption performance of the adsorbent is shorter than the time required from the start to the end of the phase transition of the latent heat storage material. The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2, wherein the heat retention performance of the latent heat storage material is set. A flow path switching means capable of switching an inflow destination of exhaust gas between the main exhaust passage and the bypass passage;
Temperature acquisition means for acquiring the temperature of the latent heat storage material;
A flow path control means for controlling the flow path switching means so that exhaust gas flows into the adsorbent when the temperature of the latent heat storage material is higher than the temperature at which the phase transition occurs;
The exhaust emission control device for an internal combustion engine according to any one of claims 2 to 4, further comprising: A temperature determination means for determining whether the temperature of the latent heat storage material reaches an inflection point at which the temperature of the latent heat storage material starts to increase after the phase transition is completed;
The flow path control means controls the flow path switching means so that exhaust gas flows into the adsorbent when it is determined that the temperature of the latent heat storage material has reached the inflection point. 6. An exhaust emission control device for an internal combustion engine according to claim 5, characterized in that: An adsorbent disposed in the exhaust passage and adsorbing specific components contained in the exhaust gas;
A catalyst arranged in the exhaust passage downstream of the adsorbent and capable of purifying exhaust gas;
A latent heat storage material that is provided in the catalyst and causes phase transition in a specific purification temperature range in which the purification rate of the catalyst is high; and
An adsorption amount acquisition means for acquiring an adsorption amount of the specific component to the adsorbent;
A heat storage amount setting means for setting a necessary heat storage amount of the latent heat storage material based on the acquired adsorption amount;
An exhaust emission control device for an internal combustion engine, comprising:   The heat storage amount setting means sets the necessary heat storage amount so that the specific amount corresponding to the acquired adsorption amount becomes a heat amount satisfying a total desorption heat amount when desorbing from the adsorbent. 8. An exhaust emission control device for an internal combustion engine according to claim 7, wherein The heat storage amount setting means includes
Input heat amount adjusting means for adjusting the input heat amount to the latent heat type heat storage material,
Heat storage amount acquisition means for acquiring the heat storage amount of the latent heat storage material,
The input heat amount adjusting means is
The exhaust purification device for an internal combustion engine according to claim 7 or 8, wherein the amount of heat input to the latent heat storage material is adjusted based on the acquired adsorption amount and heat storage amount. The input heat amount adjusting means is
A heat storage amount determination means for determining whether or not the necessary heat storage amount is stored in the latent heat storage material;
Execution of desorption operation for performing desorption operation for desorbing the specific component adsorbed on the adsorbent from the adsorbent when it is determined that the necessary heat storage amount is stored in the latent heat storage material Means,
The exhaust emission control device for an internal combustion engine according to any one of claims 7 to 9, further comprising: The exhaust passage branches from the main exhaust passage at an upstream connection portion between the main exhaust passage through which exhaust gas discharged from the internal combustion engine flows and the main exhaust passage, and is connected downstream from the upstream connection portion. A bypass passage that merges with the main exhaust passage again in the section,
The adsorbent is disposed in the bypass passage;
The catalyst including the latent heat storage material is disposed in the main exhaust passage on the downstream side of the downstream connection portion,
The exhaust emission control device further includes a flow path switching means capable of switching an inflow destination of exhaust gas between the main exhaust passage and the bypass passage,
The desorption operation executing means controls the flow path switching means so that the exhaust gas flows into the adsorbent when it is determined that the necessary heat storage amount is stored in the latent heat storage material. 11. An exhaust emission control device for an internal combustion engine according to claim 10, further comprising means. The exhaust purification device further includes temperature acquisition means for acquiring temperatures of a plurality of portions in the flow direction of the exhaust gas in the latent heat storage material,
When the temperature of the latent heat storage material becomes higher than the temperature at which the phase transition occurs in the portion satisfying the necessary heat storage amount in the plurality of portions, the heat storage amount determination means is applied to the latent heat storage material. The exhaust gas purification apparatus for an internal combustion engine according to claim 10 or 11, wherein it is determined that the necessary heat storage amount is stored.   13. The catalyst according to claim 7, wherein the latent heat storage material is provided in the catalyst in a state where the latent heat storage material is divided into a plurality of portions in a flow direction of the exhaust gas and is insulated between the plurality of portions. An exhaust purification device for an internal combustion engine according to claim 1.

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