JP2018031300A - Exhaust emission control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an engine, capable of simultaneously and appropriately performing regeneration processing for a NOx storage catalyst and regeneration processing for a particulate filter while stably supplying air into an exhaust passage on the upstream side of the particulate filter.SOLUTION: The exhaust emission control device includes a NOx storage catalyst 38 provided in an exhaust passage 26 of an engine 10, a particulate filter 39 provided in the exhaust passage 26 at its downstream side of the NOx storage catalyst 38, a bypass passage 29 connecting a combustion chamber 17 in at least one cylinder of the engine 10 and a connection part 26a of the exhaust passage 26 at the downstream side of the NOx storage catalyst 38 and at the upstream side of the particulate filter 39, and a bypass valve 44 provided in the bypass passage 29 for opening itself at a timing when the cylinder is resting.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine exhaust gas purification apparatus including a NOx storage catalyst and a particulate filter for purifying exhaust gas.

  The exhaust gas emitted from engines mounted on automobiles, etc. includes exhausts such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). Contains gas components. For this reason, a three-way catalyst for decomposing (reducing or the like) the substance and a particulate filter for capturing PM are provided in the exhaust passage of the engine.

  For example, in the case of an engine that burns in an oxidizing atmosphere by controlling the air / fuel ratio from the stoichiometric air / fuel ratio (stoichiometric) to a lean air / fuel ratio, such as a diesel engine, a three-way catalyst uses nitrogen oxides in the exhaust gas. (NOx) cannot be sufficiently purified. For this reason, some exhaust passages of this type of engine are provided with a NOx storage catalyst. The NOx storage catalyst stores NOx in the exhaust if the air-fuel ratio of the exhaust is lean, and releases and reduces the stored NOx if the air-fuel ratio of the exhaust is rich.

  In a diesel engine or the like, normally, since the air-fuel ratio of exhaust gas is lean, nitrogen oxides are stored in the NOx storage catalyst. For this reason, it is necessary to perform a regeneration process (NOx purge) for decomposing (reducing) NOx stored in the NOx storage catalyst by enriching the air-fuel ratio of the exhaust at a predetermined timing.

  Further, since the sulfur component is contained as a harmful component in the fuel, the sulfur component reacts with oxygen to become sulfur oxide (SOx) and is stored in the NOx storage catalyst instead of NOx (S poisoning). . For this reason, it is necessary to perform a regeneration process (sulfur purge: S purge) for removing sulfur oxide (SOx) at a predetermined timing. In order to perform this regeneration process (S purge), it is necessary to enrich the air-fuel ratio and raise the NOx storage catalyst to a high temperature equal to or higher than a predetermined temperature.

  In addition, particulate filters accumulate in the interior with use and increase the passage resistance. For this reason, it is necessary to perform the regeneration process for the particulate filter at a predetermined timing. That is, it is necessary to raise the temperature of the particulate filter and burn and remove the PM accumulated inside.

  Here, the regeneration process of the NOx storage catalyst (NOx purge and S purge) requires that the inside of the catalyst be in an oxygen-deficient state. On the other hand, the regeneration process of the particulate filter requires that the inside of the filter is sufficiently supplied with oxygen. For this reason, in the present engine, the regeneration process of the NOx storage catalyst and the regeneration process of the particulate filter are generally performed separately, and a large amount of fuel is consumed in each regeneration process. .

  In order to solve such problems, a NOx trap catalyst (NOx storage catalyst) provided in the exhaust passage, a PM trap (particulate filter) provided downstream of the NOx trap catalyst, and an upstream side of the PM trap An air supply device capable of supplying air to the exhaust passage, and regenerating the NOx trap catalyst (catalyst regeneration) by introducing air to the PM filter from a path different from the path passing through the NOx trap catalyst In addition, a technique for simultaneously performing PM filter regeneration (filter regeneration) has been proposed (see, for example, Patent Document 1).

  Specifically, this Patent Document 1 has, as an air supply device, an air introduction path that connects an intake passage downstream of a compressor of a supercharger and an upstream exhaust passage of a PM trap. The structure which introduce | transduces air into PM filter via is disclosed.

Japanese Patent Laid-Open No. 2003-201828

  However, with the configuration described in Patent Document 1, there is a possibility that air cannot be stably supplied to the particulate filter (PM filter).

  For example, since the pressure of the exhaust gas flowing through the exhaust passage is usually higher than the atmospheric pressure, it is necessary to increase the pressure in order to introduce air into the exhaust passage. In the configuration described in Patent Document 1, one end side of the air introduction path is connected to an intake passage downstream of the compressor that can be a negative pressure depending on the operating state of the engine. For this reason, depending on the operating state of the engine, the air in the air introduction path may have a negative pressure, and the air may flow backward from the upstream exhaust passage to the intake passage through the air introduction path.

  The present invention has been made in view of such circumstances, and stably supplies air to the exhaust passage on the upstream side of the particulate filter to regenerate the NOx storage catalyst and regenerate the particulate filter. It is an object of the present invention to provide an engine exhaust gas purification device capable of appropriately performing the above and the like simultaneously.

  An aspect of the present invention that solves the above problem is an engine exhaust purification device that includes a NOx storage catalyst provided in an exhaust passage of an engine and a particulate filter provided downstream of the NOx storage catalyst in the exhaust passage. A bypass passage that connects a combustion chamber of at least one cylinder of the engine and a connection portion of the exhaust passage downstream of the NOx storage catalyst and upstream of the particulate filter, and provided in the bypass passage, the cylinder is rested. An exhaust emission control device for an engine, comprising: a bypass valve that opens at a timing when the cylinder is in a cylinder. In this aspect of the present invention, by opening and closing the bypass valve at a predetermined timing, the air in the combustion chamber of the cylinder that is idle is introduced into the particulate filter via the bypass passage.

  Here, it is preferable that the bypass passage is connected to the combustion chamber in the vicinity of the exhaust valve provided in the cylinder. Furthermore, it is preferable that at least a part of the bypass passage is provided along the exhaust passage. Thereby, the temperature fall of the air which passes a bypass channel by the heat | fever of an exhaust channel is suppressed.

  When the engine includes a plurality of cylinders, it is preferable that each of the combustion chambers of each cylinder is connected to a connection portion of the exhaust passage via a bypass passage. In this configuration, the air in the combustion chamber of each cylinder can be sequentially supplied to the connection portion of the exhaust passage via the bypass passage.

  According to another aspect of the present invention, there is provided an exhaust purification device for an engine, comprising: a NOx storage catalyst provided in an exhaust passage of the engine; and a particulate filter provided downstream of the NOx storage catalyst in the exhaust passage. A bypass passage that connects a combustion chamber of at least one cylinder included in the engine and a connection portion downstream of the NOx storage catalyst in the exhaust passage and upstream of the particulate filter, and a bypass passage provided in the bypass passage. A bypass valve that opens and closes, a catalyst regeneration processing unit that performs regeneration processing of the NOx storage catalyst, and a filter that performs regeneration processing of the particulate filter at the timing when the regeneration processing of the NOx storage catalyst is performed by the catalyst regeneration processing unit A regeneration processing unit, wherein the filter regeneration processing unit has a temperature of the NOx storage catalyst that exceeds a predetermined temperature. At a timing that is raised, there are at least one of the cylinders causes the cylinder deactivation, to the device for purifying exhaust gas of an engine, characterized in that for opening the bypass valve provided in a cylinder which is cylinder deactivation. In such an aspect of the present invention, the air in the combustion chamber of the cylinder that is idle is introduced into the particulate filter via the bypass passage at the timing when the regeneration process of the NOx storage catalyst is being performed. Thereby, the regeneration process of the particulate filter can be simultaneously performed during the regeneration process of the NOx storage catalyst.

  Here, the regeneration process of the NOx storage catalyst by the catalyst regeneration processing unit is, for example, an S purge that releases a sulfur component from the NOx storage catalyst. In this case, the regeneration process of the particulate filter can be simultaneously performed during the S purge of the NOx storage catalyst.

  Moreover, it is preferable that the filter regeneration processing unit opens the bypass valve at a timing when the piston of the cylinder that is in the cylinder resting state is rising. Furthermore, the filter regeneration processing unit preferably closes the bypass valve when the piston reaches top dead center. Further, it is preferable that the filter regeneration processing unit opens the bypass valve at a timing when the intake valve and the exhaust valve of the cylinder that is in the closed state are closed. Thereby, the air in a combustion chamber is supplied to the connection part of an exhaust passage more efficiently via a bypass passage.

  When the engine includes a plurality of cylinders, a bypass passage is connected to the combustion chamber of each cylinder, and a bypass valve is provided corresponding to each cylinder. The filter regeneration processing unit has a predetermined temperature of the NOx storage catalyst. It is preferable that the cylinders are rested in a predetermined order at the timing when the temperature rises above the temperature, and the bypass valve corresponding to the cylinders that are rested is opened. Furthermore, it is preferable that the filter regeneration processing unit sequentially pauses the cylinders burned immediately before (one before). Thereby, the air in the combustion chamber of each cylinder is sequentially supplied to the connection part of the exhaust passage. Therefore, a sufficient amount of air is appropriately introduced into the particulate filter.

  According to the exhaust emission control device for an engine of the present invention, air can be appropriately and stably supplied to the exhaust passage on the upstream side of the particulate filter. For this reason, the regeneration process of the particulate filter can be appropriately performed while the regeneration process (S purge) of the NOx storage catalyst is being performed.

It is a figure showing the whole engine composition provided with the exhaust-air-purification device concerning the present invention. It is a figure showing the whole engine composition provided with the exhaust-air-purification device concerning the present invention. It is a figure which shows the timing of the combustion cycle in each cylinder. It is a figure explaining an example of the timing which makes each cylinder rest at the time of DPF regeneration concerning the present invention. It is a figure explaining an example of the timing which makes each cylinder rest at the time of DPF regeneration concerning the present invention. It is a figure which shows the whole structure of an engine provided with the exhaust gas purification apparatus which concerns on this invention, and is a figure which shows the modification of an exhaust gas purification apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the engine 10 according to the present embodiment is an in-line four-cylinder diesel engine, and includes an engine body 11 in which four cylinders are formed. That is, the engine body 11 includes first to fourth cylinders (cylinders) # 1 to # 4 arranged in series.

  As shown in FIG. 2, the engine body 11 has a cylinder head 12 and a cylinder block 13, and a piston 14 is accommodated in the cylinder block 13. The piston 14 is connected to the crankshaft 16 via a connecting rod 15. The piston 14, the cylinder head 12, and the cylinder block 13 form a combustion chamber 17 for each cylinder # 1 to # 4.

  The cylinder head 12 is formed with an intake port 18 that opens into the combustion chambers 17 of the respective cylinders # 1 to # 4, and an intake pipe (intake passage) 20 including an intake manifold 19 is connected to the intake port 18. The intake manifold 19 is provided with an intake pressure sensor (MAP sensor) 21 that detects intake pressure and an intake temperature sensor 22 that detects the temperature of intake air. An intake valve 23 is provided in each intake port 18, and each intake port 18 is opened and closed by the intake valve 23.

  The cylinder head 12 is formed with an exhaust port 24 that opens into the combustion chambers 17 of the cylinders # 1 to # 4. An exhaust pipe (exhaust passage) 26 including an exhaust manifold 25 is connected to the exhaust port 24. . An exhaust valve 27 is provided in the exhaust port 24, and the exhaust port 24 is opened and closed by the exhaust valve 27, similarly to the intake port 18. Since the intake valve 23 and the exhaust valve 27 have existing configurations, detailed description thereof is omitted, but the intake valve 23 and the exhaust valve 27 are opened and closed at a predetermined timing by a cam that rotates in conjunction with the reciprocating motion of the piston 14.

  Furthermore, in addition to the intake port 18 and the exhaust port 24, the cylinder head 12 is provided with a bypass port 28 that opens to the combustion chambers 17 of the cylinders # 1 to # 4. As will be described in detail later, one end side of a bypass pipe (bypass passage) 29 that connects the combustion chamber 17 and the exhaust pipe 26 of each cylinder # 1 to # 4 is connected to the bypass port 28.

  Each cylinder # 1 to # 4 is provided with an injector (fuel injection valve) 30 for injecting fuel, and each injector 30 is connected to a common rail 31. Although not shown, the common rail 31 is connected to the fuel tank via a supply pump (high pressure pump). Fuel is pumped from the fuel tank to the common rail 31 by this supply pump, and high-pressure fuel in the common rail 31 is injected from each injector 30.

  A turbocharger (supercharger) 32 is provided in the middle of the intake pipe 20 and the exhaust pipe 26. The turbocharger 32 includes a turbine 32a and a compressor 32b, and the turbine 32a and the compressor 32b are connected by a turbine shaft 32c. When the exhaust gas flows into the turbocharger 32, the turbine 32a is rotated by the flow of the exhaust gas, and the compressor 32b is rotated along with the rotation of the turbine 32a. Air (intake air) pressurized by the rotation of the compressor 32b is sent to the intake pipe 20 and supplied to the combustion chambers 17 of the cylinders # 1 to # 4.

  An air cleaner 33 is provided in the intake pipe 20 on the upstream side of the compressor 32 b of the turbocharger 32. In addition, an intercooler 34 for cooling the intake air whose temperature has increased due to pressurization by the turbocharger 32 is disposed in the intake pipe 20 on the downstream side of the compressor 32 b of the turbocharger 32. The intake pipe 20 on the downstream side of the intercooler 34 is provided with a throttle valve 35 and a throttle position sensor (TPS) 36.

  On the other hand, the exhaust pipe 26 on the downstream side of the turbine 32a of the turbocharger 32 is provided with an exhaust purification catalyst and a diesel particulate filter constituting an exhaust purification device. In this embodiment, a NOx storage catalyst 38 that is an exhaust purification catalyst is provided on the upstream side, and a diesel particulate filter (hereinafter referred to as DPF) 39 is provided on the downstream side of the NOx storage catalyst 38. An air-fuel ratio sensor (air-fuel ratio detection means) 40 for detecting the air-fuel ratio of the exhaust gas flowing out from the NOx storage catalyst 38 is provided in the exhaust pipe 26 near the outlet of the NOx storage catalyst 38. Similarly, an air-fuel ratio sensor (air-fuel ratio detecting means) 41 for detecting the air-fuel ratio of the exhaust gas flowing out from the DPF 39 is also provided in the exhaust pipe 26 near the outlet of the DPF 39. These air-fuel ratio sensors 40 and 41 may detect oxygen concentration in the exhaust gas. Further, temperature sensors (temperature detection means) 42 and 43 for detecting the temperature of the exhaust are provided in the exhaust pipe 26 near the outlets of the NOx storage catalyst 38 and the DPF 39.

In the present embodiment, only the NOx storage catalyst is provided as the exhaust purification catalyst. However, the exhaust purification catalyst only needs to include the NOx storage catalyst. For example, the exhaust purification catalyst includes a diesel oxidation catalyst and the like together with the NOx storage catalyst. Also good. In the diesel oxidation catalyst, nitrogen monoxide (NO) in the exhaust is oxidized to generate nitrogen dioxide (NO ₂ ).

Here, the NOx occlusion catalyst 38, for example, supports a noble metal such as platinum (Pt) and palladium (Pd) on a honeycomb structure carrier made of a ceramic material, and as an occlusion agent such as barium (Ba). An alkali metal or an alkaline earth metal is supported. The NOx storage catalyst 38 temporarily stores nitrogen oxides (NOx) as exhaust components in an oxidizing atmosphere, and releases NOx in a reducing atmosphere containing, for example, carbon monoxide (CO) and hydrocarbons (HC). And reduced to nitrogen (N ₂ ) or the like. Since the engine 10 according to the present embodiment is a diesel engine, the NOx occlusion catalyst 38 normally only occludes NOx, and the occluded NOx is not decomposed (reduced).

  For this reason, every time the engine 10 is operated for a predetermined period, for example, a regeneration process (NOx purge) for removing the stored NOx is performed. In this regeneration process (NOx purge), fuel as a reducing agent is supplied to the NOx storage catalyst at a predetermined timing. As a result, the inside of the NOx storage catalyst 38 becomes a reducing atmosphere, and the stored NOx is decomposed (reduced) and removed from the NOx storage catalyst 38.

  Further, the NOx occlusion catalyst 38 occludes sulfur oxide (SOx), which is an exhaust component, in the same manner as nitrogen oxide (NOx). For this reason, regeneration processing (S purge) for removing SOx at a predetermined timing is also performed. In this regeneration process (S purge), fuel as a reducing agent is appropriately supplied to the exhaust to enrich the exhaust air-fuel ratio, and the NOx storage catalyst 38 is heated to a predetermined temperature (for example, about 700 ° C.) or higher. As a result, the stored sulfur oxide (SOx) is decomposed (reduced) and removed from the NOx storage catalyst 38.

For example, the DPF 39 is a filter having a honeycomb structure formed of a ceramic material. The PM trapped in the DPF 39 is oxidized (combusted) by NO ₂ in the exhaust gas and discharged as CO ₂ , and the NO ₂ remaining in the DPF 39 is decomposed into N ₂ and discharged. The DPF 39 is also subjected to regeneration processing (DPF regeneration) at a predetermined timing in order to remove PM accumulated inside. In this DPF regeneration, similarly to the S purge of the NOx storage catalyst 38, the PM accumulated in the DPF 39 is combusted by raising the temperature of the DPF 39 to a predetermined temperature (for example, 700 ° C.) or higher.

  By the way, in the regeneration process of the DPF 39, it is necessary to raise the DPF 39 to a predetermined temperature or higher as in the S purge of the NOx storage catalyst 38 as described above. On the other hand, unlike the S purge, the exhaust air-fuel ratio of the DPF 39 is made lean. There is a need. Therefore, the S purge of the NOx storage catalyst 38 and the regeneration process of the DPF 39 have to be performed separately.

  However, since the engine 10 according to the present embodiment includes a bypass pipe 29, which will be described in detail below, as a part of the exhaust purification device, the exhaust pipe downstream of the NOx storage catalyst 38 via the bypass pipe 29 is provided. Air (oxygen) can be supplied. That is, air (oxygen) can be introduced into the DPF 39 via the bypass pipe 29. Therefore, even when the exhaust air-fuel ratio of the NOx storage catalyst 38 is enriched, the exhaust air-fuel ratio of the DPF 39 can be made lean. Therefore, the regeneration process of the DPF 39 can be performed simultaneously while the S purge of the NOx storage catalyst 38 is being performed.

  The bypass pipe 29 bypasses the NOx storage catalyst 38 and forms a flow path that connects the combustion chambers 17 and the exhaust pipes 26 of the cylinders # 1 to # 4. It is connected to each combustion chamber 17 of the main body 11 (see FIG. 1). In the present embodiment, one end side of the bypass pipe 29 is branched into four branch pipes 29a to 29d corresponding to the cylinders # 1 to # 4, and these four branch pipes 29a to 29d are connected to each cylinder #. 1 to # 4 combustion chambers 17 are connected. The other end side of the bypass pipe 29 is connected to a connection portion 26 a of the exhaust pipe 26 that is a region downstream of the NOx storage catalyst 38 and upstream of the DPF 39.

  In the present embodiment, the combustion chamber 17 of each cylinder # 1 to # 4 and the connection portion 26a of the exhaust pipe 26 are connected by a single bypass pipe 29 branched at one end into four branch pipes 29a to 29d. However, the combustion chamber 17 of each of the cylinders # 1 to # 4 and the connection portion 26a of the exhaust pipe 26 may be individually connected by, for example, four bypass pipes.

  The arrangement of the bypass pipe 29 is not particularly limited, but the bypass pipe 29 is preferably connected to each combustion chamber 17 in the vicinity of the exhaust port 24. That is, the bypass port 28 is preferably provided in the vicinity of the exhaust port 24. Further, it is preferable that at least a part of the bypass pipe 29 is provided along the exhaust pipe 26 in proximity to (or in contact with) the exhaust pipe 26. Thereby, the temperature fall of the air introduce | transduced into DPF39 via the bypass piping 29 with the heat | fever of the exhaust pipe 26 can be suppressed. Therefore, the temperature drop of the DPF 39 during the regeneration process can be suppressed, and the regeneration process of the DPF 39 can be more appropriately performed simultaneously with the execution of the NOx storage catalyst 38.

  The bypass pipes 29 are provided with bypass valves 44 at positions corresponding to the cylinders # 1 to # 4 (in the present embodiment, the branch pipes 29a to 29d). These bypass valves 44 may be provided so as to be able to open and close the bypass pipes 29 (branch pipes 29a to 29d) connected to the combustion chambers 17 of the cylinders # 1 to # 4. 17 is preferably provided at a boundary portion with respect to 17. That is, the bypass valve 44 is preferably provided so that the bypass port 28 can be opened and closed. Unlike the intake valve 23 and the exhaust valve 27 that open and close in conjunction with the reciprocating motion of the piston 14, the bypass valve 44 is configured to be opened and closed independently by a driving device 45 configured by an electric motor or the like. .

  As described above, the engine 10 according to the present embodiment includes the NOx storage catalyst 38 and the DPF 39, and the bypass pipe 29 that connects the combustion chamber 17 of each cylinder # 1 to # 4 and the connection portion 26a of the exhaust pipe 26. And a bypass valve 44 that opens and closes the bypass pipe 29 is provided as the exhaust gas purification device 100.

  The exhaust emission control device 100 rests at least one of the first to fourth cylinders # 1 to # 4 when the regeneration process (S purge) of the NOx storage catalyst 38 is being performed, The bypass valves 44 corresponding to the first to fourth cylinders # 1 to # 4 that are cylinder-opened are opened and closed at a predetermined timing.

  Thereby, the air (oxygen) in the combustion chamber 17 is supplied to the connection portion 26 a of the exhaust pipe 26 via the bypass pipe 29. Although the pressure of the exhaust gas flowing through the exhaust pipe 26 is higher than the atmospheric pressure, the air flowing through the bypass pipe 29 is pressurized in the combustion chamber 17, and thus is well supplied to the connection portion 26 a of the exhaust pipe 26. Since the air (oxygen) supplied to the connection portion 26a of the exhaust pipe 26 is introduced into the DPF 39 together with the exhaust gas flowing out from the NOx storage catalyst 38, the exhaust air / fuel ratio of the NOx storage catalyst 38 is enriched. The exhaust air-fuel ratio of the DPF 39 can be made lean.

  Accordingly, during the S purge of the NOx storage catalyst 38, the regeneration process of the DPF 39 can be simultaneously performed using the exhaust gas whose temperature has been raised for the S purge of the NOx storage catalyst 38. As a result, it is not necessary to inject fuel for DPF regeneration to raise the temperature of the exhaust gas, so that fuel consumption can be suppressed.

  The engine 10 includes an electronic control unit (ECU) 50. The ECU 50 includes an input / output device, a storage device that stores a control program, a control map, and the like, a central processing unit, timers, and counters. It has been. The ECU 50 is supplied from various sensors including the intake pressure sensor (MAP sensor) 21, intake air temperature sensor 22, throttle position sensor (TPS) 36, air-fuel ratio sensors 40 and 41, temperature sensors 42 and 43, and the like. Based on the information, comprehensive control of the engine 10 is performed, and the cylinder rest state of the engine 10 and the operating state of the bypass valve 44 are also appropriately controlled. That is, the ECU 50 also functions as a part of the exhaust purification device 100 provided in the engine 10.

  Hereinafter, an example of the operation of the exhaust emission control device 100 included in the engine 10 according to the present embodiment, particularly, the operation during the regeneration process of the DPF 39 will be described.

  The ECU 50 includes an exhaust purification unit 53 including a catalyst regeneration processing unit 51 and a filter regeneration processing unit 52 (see FIG. 1). The catalyst regeneration processing unit 51 performs regeneration processing (NOx purge and S purge) of the NOx storage catalyst 38 at a predetermined timing. In addition, since the method of the regeneration process (NOx purge and S purge) of the NOx occlusion catalyst 38 by the catalyst regeneration processor 51 is an existing technique, a detailed description thereof is omitted here.

  The filter regeneration processing unit 52 executes the regeneration process (DPF regeneration) of the DPF 39 at the timing when the regeneration process (S purge) of the NOx storage catalyst 38 is being performed by the catalyst regeneration processing unit 51. Specifically, the filter regeneration processing unit 52 is provided near, for example, the temperature sensor 42 provided near the outlet of the NOx storage catalyst 38 or the outlet of the DPF 39 during the S purge of the NOx storage catalyst 38. Based on the detection result of the temperature sensor 43, it is determined whether or not the NOx storage catalyst 38 has risen above a predetermined temperature.

  Then, at the timing when the NOx storage catalyst 38 rises to a predetermined temperature or higher, at least one of the first to fourth cylinders # 1 to # 4 is made to rest. That is, the fuel supply from the injector 30 to the combustion chamber 17 corresponding to the cylinder to be rested is stopped. Further, the filter regeneration processing unit 52 opens the bypass valve 44 corresponding to the cylinder that has been deactivated at a predetermined timing. As a result, air (oxygen) in the combustion chamber 17 of the cylinder that has been deactivated is sequentially supplied to the connection portion 26 a of the exhaust pipe 26 via the bypass pipe 29. That is, the air in the combustion chamber 17 that has been rested is introduced into the DPF 39 via the bypass pipe 29. With the introduction of air into the DPF 39, the exhaust air-fuel ratio in the DPF 39 is made lean and the DPF 39 is regenerated.

  During the regeneration process of the DPF 39, the filter regeneration processing unit 52 determines the amount of air introduced into the DPF 39 so that the exhaust air-fuel ratio of the DPF 39 is kept lean based on the detection result of the air-fuel ratio sensor 41. Control as appropriate. Further, the filter regeneration processing unit 52 appropriately controls the amount of air introduced into the DPF 39 so that the temperature of the DPF 39 does not excessively increase based on the detection result of the temperature sensor 43.

  Here, the cylinder to be deactivated may be determined as appropriate, and a specific cylinder may be deactivated. For example, the cylinder to be deactivated may be appropriately changed according to the operating state of the engine 10 or the like. It may be. Since the engine 10 according to the present embodiment is a four-stroke in-line four-cylinder engine, when a specific cylinder is deactivated, the moving direction of the piston 14 is the same among the first to fourth cylinders # 1 to # 4. Preferably, the two cylinders (for example, the first cylinder # 1 and the fourth cylinder # 4, or the second cylinder # 2 and the third cylinder # 3) are simultaneously deactivated. Thus, sufficient air can be supplied to the DPF 39 via the bypass pipe 29 while suppressing vibration during traveling of the vehicle. Of course, two cylinders do not necessarily have to be deactivated, one specific cylinder may be deactivated, and three cylinders may be deactivated. When only a specific cylinder is always deactivated, the bypass pipe 29 only needs to be connected to the specific cylinder.

  Further, the filter regeneration processing unit 52 may rest the first to fourth cylinders # 1 to # 4 in a predetermined order during the regeneration process of the DPF 39. At that time, the order in which the first to fourth cylinders # 1 to # 4 are deactivated is not particularly limited, but it is preferable to sequentially deactivate the cylinders burned immediately before (one before). For example, if one cycle of each of the first to fourth cylinders # 1 to # 4 is one set, in the next set, it is preferable that the cylinders burned at the end of the previous set are sequentially decommissioned. .

  Specifically, the engine 10 according to the present embodiment is a four-stroke engine, and each stroke of the combustion cycle (intake stroke, compression stroke, combustion stroke, exhaust stroke) in the first to fourth cylinders # 1 to # 4. Is normally performed at the timing shown in FIG. That is, when the combustion stroke is executed in the first cylinder # 1, thereafter, the combustion stroke is executed in the order of the second cylinder # 2, the fourth cylinder # 4, and the third cylinder # 3.

  Therefore, for example, as shown in FIG. 4, the first cylinder # 1, the second cylinder # 2, and the fourth cylinder # 4 are burned in the first set (first set) during the regeneration process. When the third cylinder # 3 is deactivated, in the next set (second set), the first cylinder # 1, the second cylinder # 2, and the third cylinder # 3 are burned, and the fourth cylinder # 3 is burned. The cylinder # 4 is deactivated. Next, in the third set, the first cylinder # 1, the fourth cylinder # 4, and the third cylinder # 3 are burned, and the second cylinder # 2 is deactivated. Further, in the fourth set, the first cylinder # 1 is deactivated, and the second cylinder # 2, the fourth cylinder # 4, and the third cylinder # 3 are combusted.

  That is, in this example, the air in the combustion chamber 17 of the third cylinder # 3 is introduced into the DPF 39 in the first set, and the air in the combustion chamber 17 of the fourth cylinder # 4 is introduced into the DPF 39 in the second set. Is done. In the third set, the air in the second cylinder # 2 is introduced into the DPF 39, and in the fourth set, the air in the first cylinder # 1 is introduced into the DPF 39. After that, the first set to the fourth set are repeated.

  Further, for example, as shown in FIG. 5, the first cylinder # 1, the third cylinder # 3, and the fourth cylinder # 3 are burned in the first set (first set), and the second cylinder # 2 is burned. In the next set (second set), the second cylinder # 2, the third cylinder # 3, and the fourth cylinder # 4 are burned, and the first cylinder # 1 is deactivated. Let Next, in the third set, the first cylinder # 1, the second cylinder # 2, and the fourth cylinder # 4 are burned, and the third cylinder # 3 is deactivated. Further, in the fourth set, the fourth cylinder # 4 is deactivated, and the first cylinder # 1, the second cylinder # 2, and the third cylinder # 3 are combusted.

  That is, in this example, the air in the combustion chamber 17 of the second cylinder # 2 is introduced into the DPF 39 in the first set, and the air in the combustion chamber 17 of the first cylinder # 1 is introduced into the DPF 39 in the second set. Is done. In the third set, the air in the third cylinder # 3 is introduced into the DPF 39, and in the fourth set, the air in the fourth cylinder # 4 is introduced into the DPF 39. Thereafter, the first set to the fourth set are repeated.

  In this way, the first to fourth cylinders # 1 to # 4 are sequentially deactivated, and the air in the combustion chambers 17 of the deactivated cylinders is introduced into the DPF 39, so that sufficient air is appropriately supplied to the DPF 39. And vibrations of the running vehicle can also be effectively suppressed. It should be noted that when the regeneration process is started, the cylinder to be initially deactivated may be appropriately determined according to the operating state of the engine 10 or the like.

  By the way, the bypass valve 44 provided in the bypass pipe 29 needs to be opened at a timing at which the air in the combustion chamber 17 can be discharged to the bypass pipe 29. The timing at which the filter regeneration processing unit 52 opens the bypass valve 44 may be determined as appropriate. However, the filter regeneration processing unit 52 activates the bypass valve 44 at the timing when the piston 14 of the cylinder that is in the cylinder-cylinder rises. It is preferable to open the valve. In other words, the bypass valve 44 is preferably opened while the piston 14 is moving from the bottom dead center toward the top dead center. Furthermore, it is preferable that the filter regeneration processing unit 52 closes the bypass valve 44 when the piston 14 of the cylinder that is in the cylinder-rested state reaches the top dead center. Thus, the air in the combustion chamber 17 can be supplied to the connection portion 26 a of the exhaust pipe 26 via the bypass pipe 29 without causing the air to flow backward from the bypass pipe 29 to the combustion chamber 17.

  Furthermore, it is preferable that the filter regeneration processing unit 52 opens the bypass valve 44 at the timing when the intake valve 23 and the exhaust valve 27 of the cylinders that are in the closed state are closed, for example, at the compression stroke. Thereby, the air in the combustion chamber 17 can be efficiently discharged to the bypass pipe 29. Therefore, a sufficient amount of air can be introduced into the DPF 39 via the bypass pipe 29. Further, when the air in the combustion chamber 17 is supplied to the connection portion 26a of the exhaust pipe 26 through the bypass pipe 29 in the compression stroke, the amount of air discharged from the exhaust port 24 in the exhaust stroke can be suppressed to a small amount. That is, the amount of air supplied to the NOx storage catalyst 38 from the cylinders that are idle is suppressed. As a result, the temperature of the NOx storage catalyst 38 can be appropriately controlled, and the S purge can be carried out satisfactorily.

  Further, when the air in the combustion chamber 17 is supplied to the connection portion 26a of the exhaust pipe 26 through the bypass pipe 29 in the compression stroke, the exhaust purification device 100 is configured by an electric motor or the like as shown in FIG. It is preferable to include a drive device 46 that opens and closes 23. That is, the intake valve 23 is preferably configured not only to be opened and closed by a cam that rotates in conjunction with the reciprocating motion of the piston 14, but also to be able to open the closed intake valve 23 by the drive device 46. . And when supplying the air in the combustion chamber 17 to the connection part 26a of the exhaust pipe 26 via the bypass piping 29 in the compression stroke, when the piston 14 moves from the top dead center toward the bottom dead center thereafter ( The intake valve 23 is preferably opened by the drive device 46 at a timing corresponding to the combustion stroke). Thereby, when the piston 14 moves from the top dead center toward the bottom dead center, it is possible to suppress the movement of the piston 14 from being inhibited due to the negative pressure in the combustion chamber 17.

  As mentioned above, although one embodiment of the present invention was described, of course, the present invention is not limited to the above-described embodiment.

  For example, in the above-described embodiment, a configuration in which the NOx storage catalyst and the DPF are housed in separate housings is illustrated, but the NOx storage catalyst and the DPF may be housed in one housing. Good.

  Further, for example, in the above-described embodiment, the present invention has been described by exemplifying a so-called two-valve engine in which each cylinder includes one intake valve and one exhaust valve. However, the present invention is described as a so-called four-valve engine. It can also be applied to.

  For example, in the above-described embodiment, the present invention has been described by taking the exhaust purification device mounted on the diesel engine as an example. However, the present invention can of course be applied to the exhaust purification device mounted on the gasoline engine.

DESCRIPTION OF SYMBOLS 10 Engine 11 Engine main body 12 Cylinder head 13 Cylinder block 14 Piston 15 Connecting rod 16 Crankshaft 17 Combustion chamber 18 Intake port 19 Intake manifold 20 Intake pipe 21 Intake pressure sensor (MAP sensor)
22 Intake air temperature sensor 23 Intake valve 24 Exhaust port 25 Exhaust manifold 26 Exhaust pipe (exhaust passage)
26a Connection 27 Exhaust valve 28 Bypass port 29 Bypass piping (bypass passage)
29a to 29d Branch pipe 30 Injector 31 Common rail 32 Turbocharger 32a Turbine 32b Compressor 32c Turbine shaft 33 Air cleaner 34 Intercooler 35 Throttle valve 36 Throttle position sensor (TPS)
38 NOx storage catalyst 39 Diesel particulate filter (DPF)
40, 41 Air-fuel ratio sensor 42, 43 Temperature sensor 44 Bypass valve 45, 46 Drive unit 50 ECU
51 catalyst regeneration processing unit 52 filter regeneration processing unit 53 exhaust gas purification unit 100 exhaust gas purification device

Claims (11)

A NOx storage catalyst provided in the exhaust passage of the engine;
An exhaust purification device for an engine comprising: a particulate filter provided downstream of the NOx storage catalyst in the exhaust passage;
A bypass passage connecting a combustion chamber of at least one cylinder provided in the engine and a connection portion of the exhaust passage downstream of the NOx storage catalyst and upstream of the particulate filter;
An exhaust purification device for an engine, comprising: a bypass valve provided in the bypass passage and opened at a timing when the cylinder is idle. The exhaust emission control device for an engine according to claim 1,
An exhaust purification device for an engine, wherein the bypass passage is connected to the combustion chamber in the vicinity of an exhaust valve provided in the cylinder. The engine exhaust gas purification apparatus according to claim 1 or 2,
An exhaust emission control device for an engine, wherein at least a part of the bypass passage is provided along the exhaust passage. The engine exhaust gas purification apparatus according to any one of claims 1 to 3,
The engine includes a plurality of the cylinders;
Each of the combustion chambers of each cylinder is connected to the connection portion of the exhaust passage via the bypass passage. A NOx storage catalyst provided in the exhaust passage of the engine;
An exhaust purification device for an engine comprising: a particulate filter provided downstream of the NOx storage catalyst in the exhaust passage;
A bypass passage connecting a combustion chamber of at least one cylinder included in the engine and a connection portion of the exhaust passage downstream of the NOx storage catalyst and upstream of the particulate filter;
A bypass valve provided in the bypass passage for opening and closing the bypass passage;
A catalyst regeneration processing unit for performing regeneration processing of the NOx storage catalyst;
A filter regeneration processing unit that performs regeneration processing of the particulate filter at a timing when regeneration regeneration of the NOx storage catalyst is being performed by the catalyst regeneration processing unit,
The filter regeneration processing unit
At a timing when the temperature of the NOx storage catalyst rises to a predetermined temperature or higher, at least one of the cylinders is rested, and the bypass valve provided in the resting cylinder is opened. Exhaust gas purification device for the engine. The engine exhaust gas purification apparatus according to claim 5,
The engine exhaust purification apparatus according to claim 1, wherein the regeneration process of the NOx storage catalyst by the catalyst regeneration processing unit is an S purge for releasing a sulfur component from the NOx storage catalyst. The engine exhaust gas purification apparatus according to claim 5 or 6,
The exhaust gas purifying apparatus for an engine, wherein the filter regeneration processing unit opens the bypass valve at a timing when a piston of the cylinder that has been rested rises. The engine exhaust gas purification apparatus according to claim 7,
The exhaust gas purifying apparatus for an engine, wherein the filter regeneration processing unit closes the bypass valve when the piston reaches top dead center. The engine exhaust gas purification apparatus according to any one of claims 5 to 8,
The engine exhaust purification device according to claim 1, wherein the filter regeneration processing unit opens the bypass valve at a timing when the intake valve and the exhaust valve of the cylinder that is in a closed state are closed. The engine exhaust gas purification apparatus according to any one of claims 5 to 9,
The engine includes a plurality of the cylinders;
The bypass passage is connected to the combustion chamber of each cylinder, and the bypass valve is provided corresponding to each cylinder,
The filter regeneration processing unit
The cylinders are rested in a predetermined order at the timing when the temperature of the NOx storage catalyst rises to a predetermined temperature or higher, and the bypass valve corresponding to the cylinders that are rested is opened. Exhaust gas purification device for the engine. The engine exhaust gas purification apparatus according to claim 10, wherein
The exhaust gas purifying apparatus for an engine, wherein the filter regeneration processing unit sequentially rests the cylinders burned immediately before.