JP2009041406A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate NOx in exhaust gas by using, as reducing components, the hydrocarbon compounds contained in the exhaust gas in an exhaust emission control system for purifying the exhaust gas from the internal combustion engine of a vehicle. <P>SOLUTION: This exhaust emission control system comprises an upstream side control part 44 and a downstream side control part 46 including a catalyst having an NOx eliminating performance which are connected in series in an exhaust passage 35. The exhaust emission control system further comprises a collection passage 47 which communicates with an exhaust passage E1 on the upstream side of the upstream side control part 44 and in which a collection valve 52 is installed, a container 50 communicating with the other end of the collection passage 47, a discharge passage 56 which communicates with the container 50, which communicates with an exhaust passage E2 between the upstream side control part 44 and the downstream side control part 46, and in which a release valve 60 is installed, and a release valve control means for controllably opening the release valve 60 to release the discharge gas including the reducing components in the container 50. The exhaust gas is collected from the exhaust passage E1 into the container 50 during the start of the engine and during the accelerating operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification system used for purifying NOx in exhaust gas discharged from an internal combustion engine.

As a catalyst for purifying NOx in exhaust gas of an internal combustion engine, a NOx occlusion reduction type catalyst and a selective reduction type NOx catalyst are known. In a NOx occlusion reduction type catalyst, as is known, NOx is occluded in the catalyst as nitrate, for example, the exhaust gas is temporarily made rich to decompose the nitrate to release NOx, and the NOx occlusion capacity Is recovered and NOx reacts with reducing components such as HC and CO present in the atmosphere to be reduced and purified to N ₂ . On the other hand, in the selective reduction type NOx catalyst, NOx is reduced or decomposed in an oxygen-excess atmosphere and in the presence of a reducing agent.

  For example, Patent Document 1 discloses an exhaust purification device for an internal combustion engine having a selective reduction type NOx catalyst. The apparatus includes a reducing agent storage chamber for storing a gel-like reducing agent, and a reducing agent supply means for supplying the gel-like reducing agent stored in the reducing agent storage chamber to an exhaust passage upstream of the selective reduction type NOx catalyst. And. Gelled urea is used as the gelled reducing agent, and this gelled urea is based on the NOx emission amount derived from the engine operating state or the NOx concentration of the exhaust gas detected by the NOx sensor. An amount corresponding to the calculated amount of NOx emission is supplied.

JP 2000-310112 A

  However, in the apparatus described in Patent Document 1, when the amount of stored reducing agent falls below a predetermined amount, it is necessary to replenish it from the outside only for that purpose. Therefore, there is a possibility that the driver feels troublesome when using the device described in Patent Document 1.

  Therefore, it is desirable to use a reducing agent that is normally generated or used in an internal combustion engine, rather than being replenished from the outside. For example, it is conceivable to directly supply the fuel of the internal combustion engine to the exhaust passage as a reducing agent. However, this increases the amount of fuel consumed, which is not preferable from the viewpoint of improving fuel consumption.

  By the way, the exhaust gas of the internal combustion engine mounted on the vehicle may contain a hydrocarbon compound, carbon monoxide, and the like, and the concentration of the exhaust gas just exhausted from the combustion chamber becomes considerably high depending on the operation state or the like. Therefore, it is desirable to use exhaust gas containing such components as the reducing agent.

  Accordingly, the present invention has been made in view of such a point, and an object of the present invention is to purify NOx in exhaust gas by using a hydrocarbon compound or carbon monoxide contained in the exhaust gas as a reducing component. There is.

  In order to achieve the above object, an exhaust gas purification system of the present invention includes an upstream purification unit and a downstream purification unit arranged in series in an exhaust passage of an internal combustion engine, and the downstream purification unit has a NOx purification capability. In the exhaust gas purification system including the catalyst, the recovery passage provided with a recovery valve and the other end of the recovery passage are connected to the exhaust passage upstream of the upstream purification section. The exhaust gas storage container is connected to one end of the exhaust gas storage container and the other end is connected to the exhaust passage between the upstream purification unit and the downstream purification unit, and a discharge valve is provided. It is characterized by comprising a discharge passage and a discharge valve control means for controlling the opening of the discharge valve so as to release the exhaust gas containing the reducing component in the exhaust gas storage container.

  According to the above configuration, the release valve is controlled to be opened by the release valve control means so as to release the exhaust gas containing the reducing component in the exhaust gas storage container into the exhaust passage between the upstream side purification unit and the downstream side purification unit. Therefore, the exhaust gas containing the reducing component is supplied to the downstream purification unit. Therefore, the catalyst having the NOx purification capability of the downstream side purification unit can purify NOx in the exhaust gas by using the reducing component in the exhaust gas.

  The upstream purification unit may be configured to have an oxidation capability or a PM trapping function. By doing so, it becomes possible to purify the hydrocarbon compound, carbon monoxide or PM (particulate matter) in the exhaust gas that has not been collected in the exhaust gas storage container in the upstream purification unit.

  The exhaust gas purification system further includes recovery valve control means for controlling the opening degree of the recovery valve provided in the recovery passage, and the recovery valve control means controls the recovery valve during engine start-up or acceleration operation. It is good to control valve opening. Exhaust gas with a high concentration of reducing components such as hydrocarbon compounds and carbon monoxide is generally discharged from the combustion chamber to the exhaust passage during engine start-up or acceleration operation. By doing so, exhaust gas containing more reducing components The gas can be recovered.

  Further, the various exhaust gas purification systems include an exhaust throttle valve provided downstream of a communication point between the exhaust passage upstream of the upstream purification unit and the recovery passage in the exhaust passage of the internal combustion engine. And an exhaust throttle valve control means for controlling the opening degree of the exhaust throttle valve, and the exhaust throttle valve control means preferably controls the exhaust throttle valve to be closed when the engine is started. By doing so, it becomes possible to increase the pressure of the exhaust gas in the exhaust passage upstream of the exhaust throttle valve. Therefore, as described above, the exhaust gas having a high concentration of the reducing component discharged from the combustion chamber to the exhaust passage at the time of starting the engine can be recovered with a higher pressure.

  In addition, in the various exhaust gas purification systems described above, one or a plurality of jet outlets may be provided at the other end portion of the discharge passage on the exhaust passage side. By doing so, it becomes possible to effectively mix the exhaust gas discharged from the discharge passage and the exhaust gas flowing from the upstream side without passing through the exhaust gas storage container. In particular, the jet port may be positioned in the vicinity of an exhaust passage reduction portion formed in the exhaust passage between the upstream purification unit and the downstream purification unit. By doing so, they can be mixed more effectively.

  Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  First, the first embodiment will be described. FIG. 1 shows a schematic configuration of an internal combustion engine system for a vehicle to which the exhaust gas purification system of the first embodiment is applied. The internal combustion engine 10 is a type of internal combustion engine, that is, a diesel engine, that spontaneously ignites by directly injecting light oil as fuel into a combustion chamber 14 in a compressed state from a fuel injection valve 12. Although only one cylinder 16 is shown in FIG. 1, the internal combustion engine 10 can have a plurality of cylinders, for example, a four-cylinder engine.

  An intake port 20 facing the combustion chamber 14 of the cylinder 16 and defining a part of the intake passage 18 is formed in the cylinder head 22 and is opened and closed by an intake valve 24 driven by a valve mechanism 23. An intake manifold 26 that defines a part of the intake passage 18 is connected to the cylinder head 22, and an intake pipe 28 that also defines a part of the intake passage 18 is connected to the upstream side thereof. An air cleaner 30 is provided on the upstream end side of the intake pipe 28 to remove dust and the like in the air guided to the intake passage 18. A throttle valve 34 whose opening is adjusted by the throttle actuator 32 is provided in the middle of the intake pipe 28.

  On the other hand, an exhaust port 36 facing the combustion chamber 14 of the cylinder 16 and defining a part of the exhaust passage 35 is formed in the cylinder head 22 and is opened and closed by an exhaust valve 38 driven by the valve mechanism 23. . An exhaust manifold 40 that defines a part of the exhaust passage 35 is connected to the cylinder head 22, and an exhaust pipe 42 that also defines a part of the exhaust passage 35 is connected to the downstream side of the cylinder head 22. A purification device for purifying the exhaust gas is provided in the middle of the exhaust pipe 42. The purification device includes two purification units in series, and the two purification units are an upstream purification unit 44 and a downstream purification unit 46 in order from the upstream side.

  Here, the upstream purification unit 44 is an oxidation catalyst that oxidizes and purifies hydrocarbon compounds (HC) and carbon monoxide (CO), which are unburned components in the exhaust gas. The upstream purification unit 44 may be configured as a DPR (Diesel Particulate Reduction) catalyst that collects PM in exhaust gas and burns and removes it, or further includes it. That is, the upstream side purification unit 44 can be configured to have an oxidation capability or a PM trapping function.

The downstream catalyst 46 is a NOx storage reduction catalyst (NSR: NOx Storage Reduction) that reduces and purifies nitrogen oxides (NOx) in the exhaust gas. That is, the downstream catalyst 46 includes a catalyst having NOx purification ability. This NSR is formed by supporting a noble metal such as Pt and a NOx occlusion material selected from alkali metals and alkaline earth metals on a porous oxide such as alumina. Specifically, NO in the exhaust gas in a lean atmosphere is oxidized by the noble metal to become NOx, reacts with the NOx storage material, and is stored as nitrate in the catalyst. Then, by temporarily setting the exhaust gas to a rich atmosphere, that is, an atmosphere with a large amount of reducing components, nitrate is decomposed and NOx is released, and the NOx occlusion material recovers the NOx occlusion ability, and NOx is abundant in the atmosphere. It is reduced and purified to N ₂ by reacting with reducing components such as HC and CO present in the catalyst.

  A recovery passage 47 communicates with an exhaust passage E1 upstream of the upstream purification section 44 in the exhaust passage 35. The collection passage 47 is defined by a collection pipe 48. The other end of the recovery passage 47 whose one end communicates with the exhaust passage E1 upstream of the upstream purification section 44 is communicated with the exhaust gas storage container (container) 50. A recovery valve 52 is provided in the middle of the recovery passage 47. When the recovery valve 52 is opened, the exhaust passage E1 communicates with the inside of the container 50, while the recovery valve 52 is closed. Thus, the communication state between the exhaust passage E1 and the container 50 is blocked. The recovery valve 52 is a poppet type valve that is not shown in FIG. 1, and its valve body is driven by a drive actuator 54.

  In the exhaust passage 35, a discharge passage 56 is communicated with an exhaust passage E <b> 2 between the upstream side purification unit 44 and the downstream side purification unit 46. The discharge passage 56 is defined by a discharge pipe 58. The other end portion of the discharge passage 56 whose one end portion is communicated with the exhaust passage E <b> 2 is communicated with the inside of the container 50. A discharge valve 60 is provided in the middle of the discharge passage 56. When the discharge valve 60 is opened, the exhaust passage E2 communicates with the inside of the container 50, while the discharge valve 60 is closed. Thus, the communication state between the exhaust passage E2 and the inside of the container 50 is blocked. The discharge valve 60 is a poppet type valve not shown in FIG. 1, and its valve body is driven by a drive actuator 62.

  As will be described later, the exhaust gas is collected and accommodated in the container 50 so that it can be used (released). Then, the nozzle 64 is provided with a discharge passage so that the exhaust gas stored in the container 50 can be discharged to the exhaust passage E2, more preferably to the downstream purification section 46 with a predetermined direction and a predetermined momentum. 54 is provided at the end of the exhaust passage E2 side. The nozzle 64 is provided with one jet outlet.

  The valve mechanism 23 controls the intake valve 24 and the exhaust valve 38 individually at an arbitrary opening degree and timing in synchronization with the rotation of the crankshaft 66 to which the piston 64 is connected via the connecting rod 62. It is a mechanism that can do this. Specifically, the valve operating mechanism 23 includes solenoids individually provided for the intake valve 24 and the exhaust valve 38, respectively. The valve mechanism 23 can realize valve overlap in which the intake valve 24 and the exhaust valve 38 are simultaneously opened. As the valve mechanism 23, for example, a variable valve timing mechanism (VVT) that can arbitrarily change the valve timing and the cam profile by switching two kinds of cams applied to a single valve by hydraulic pressure. It may be used.

  The internal combustion engine 10 includes various sensors that electrically output signals for detecting (derivation or estimation) of various values in an electronic control unit (ECU) 70. Here, some of them will be specifically described. An air flow meter 72 for detecting the amount of intake air is provided in the intake pipe 28. An intake air temperature sensor 74 for detecting the temperature of the intake air is provided in the vicinity of the air flow meter 72. An intake pressure sensor 76 is provided. Further, an accelerator opening sensor 80 for detecting the position corresponding to the depression amount of the accelerator pedal 78 operated by the driver, that is, the accelerator opening is provided. A throttle position sensor 82 for detecting the opening of the throttle valve 34 is also provided. A crank position sensor 86 for detecting a crank rotation signal of the crankshaft 66 is attached to the cylinder block 84 in which the piston 64 reciprocates. Here, the crank position sensor 86 is also used as an engine speed sensor for detecting the engine speed (engine speed). Furthermore, a pressure sensor 88 for detecting the pressure in the container 50 is also provided. Further, a temperature sensor 90 for detecting the cooling water temperature of the internal combustion engine 10 is provided.

  The ECU 70 is composed of a microcomputer including a CPU, ROM, RAM, A / D converter, input interface, output interface, and the like. The various sensors are electrically connected to the input interface. Based on the output signals (detection signals) from these various sensors, the ECU 70 electrically outputs an operation signal (drive signal) from the output interface so that the internal combustion engine 10 can be smoothly operated according to a preset program. Output. In this way, the operation of the fuel injection valve 12, the operation of the valve mechanism 23, the throttle valve 34, the recovery valve 52, the release valve 60, and the like are controlled. However, the ECU 70 outputs an operation signal to each actuator 32, 54, 62 in order to control the opening degrees of the throttle valve 34, the recovery valve 52, and the release valve 60. However, the ECU 70 includes a function of time measuring means that enables time to be measured for control described later. Here, the release valve control means for controlling the opening degree of the release valve 60 includes the actuator 62 and a part of the ECU 70. The recovery valve control means for controlling the opening degree of the recovery valve 52 includes an actuator 54 and a part of the ECU 70.

  In the internal combustion engine 10, the intake air amount derived based on the output signal from the air flow meter 72, the engine speed derived based on the output signal from the crank position sensor 86, that is, the engine load and the engine speed. The fuel injection amount (fuel amount or fuel injection time) and fuel injection timing are set based on the operating state. Based on the fuel injection amount and the fuel injection timing, fuel is injected from the fuel injection valve 12.

  However, at the time of engine startup including cold start, the fuel injection amount and fuel injection timing are derived based on the cooling water temperature or the like due to a large change in the intake air amount. The fuel injection amount at this time is made larger than the basic fuel injection amount, and the air-fuel ratio of the air-fuel mixture formed in the combustion chamber 14 becomes rich. Specifically, at the time of cold start, the lower the coolant temperature, the worse the fuel vaporization state. Therefore, the lower the coolant temperature, the higher the fuel injection amount so that the fuel ratio becomes a rich air-fuel ratio. Whether the engine is starting or not can be determined by the ECU 70 based on the engine speed. Specifically, when the engine speed is equal to or lower than a predetermined speed such as 500 rpm, the ECU 70 determines that the engine is starting. However, in an internal combustion engine that is in an operating state after the start time, hysteresis is provided so that it is not determined that the engine has been started even when the engine speed becomes equal to or lower than the predetermined speed.

  Further, the acceleration operation is a time when the driver depresses the accelerator pedal 78. At this time, a sudden change in the intake air amount is brought about by a change in the opening of the throttle valve 34 or the like. On the other hand, since the fuel follow-up delay occurs, the air-fuel ratio becomes thin particularly at the initial stage of acceleration, so that the amount of fuel to be injected is increased with respect to the intake air amount. Therefore, the air-fuel ratio of the air-fuel mixture formed in the combustion chamber 14 becomes rich. During the acceleration operation, the warm-up of the internal combustion engine 10 is almost finished.

  In this way, the air-fuel ratio of the air-fuel mixture formed in the combustion chamber 14 becomes rich at the time of engine start, particularly during cold start or acceleration operation, so that the exhaust gas is discharged from the combustion chamber 14 to the exhaust passage 35 at this time. The concentration of HC, CO, etc. in the exhaust gas can be high. These reducing components are basically purified by the oxidation function of the upstream side purification unit 44. However, here, the exhaust gas containing high-concentration HC, CO, etc. is recovered from the exhaust passage E1 before reaching the upstream purification section 44, and the recovered exhaust gas is supplied to the exhaust passage E2 at an appropriate time. By doing so, the NOx occlusion ability of the downstream purification unit 46 is restored and NOx purification is achieved as described later. In other words, the downstream purification unit 46 purifies NOx using HC or CO contained in the exhaust gas as a reducing component. Hereinafter, the recovery and release of such exhaust gas for NOx purification will be described in detail.

  First, exhaust gas recovery will be described. Here, the exhaust gas is collected when the pressure in the container 50 is equal to or lower than a first predetermined pressure (for example, 1.2 kPa as a gauge pressure). This is to prevent further recovery of exhaust gas when a sufficient amount of exhaust gas is stored in the container 50. Based on the engine speed derived based on the output signal from the crank position sensor 86, the coolant temperature derived based on the output signal from the temperature sensor 90, etc. It is determined whether or not it is a start time, that is, a start time before warm-up. As described above, at the time of cold start, since the fuel injection amount is particularly increased and the ratio of HC, CO, etc. contained in the exhaust gas is predicted to be high, the exhaust gas should be collected at this time in advance. A predetermined program is incorporated in the ECU 70.

  In addition to this, a predetermined program is incorporated in advance so that the ECU 70 collects exhaust gas during acceleration, that is, during acceleration operation. This is because during acceleration, the ratio of HC, CO, etc. contained in the exhaust gas is predicted to be high as described above. The ECU 70 determines whether or not the vehicle is accelerating based on the change rate of the accelerator opening (accelerator opening speed). The ECU 70 obtains the accelerator opening speed from the accelerator opening derived based on the output signal from the accelerator opening sensor 80, and accelerates when the derived accelerator opening speed is equal to or higher than a predetermined speed stored in the ROM in advance. Judged as medium. In addition to this, the ECU 70 may determine that the vehicle is accelerating when the coolant temperature is equal to or higher than a predetermined temperature.

  The ECU 70 controls the recovery valve 52 to open when the pressure in the container 50 is equal to or lower than the first predetermined pressure and when cold starting or during acceleration. In other words, the ECU 70 outputs an operation signal to the actuator 54 so that the recovery valve 52 in the closed state is opened at other times. At this time, the pressure in the exhaust passage, that is, the pressure at the communication point between the recovery passage 47 and the exhaust passage E1 is, for example, 1.5 kPa, so the pressure in the exhaust passage E1 is higher than the pressure in the container 50. Accordingly, the exhaust gas is collected in the container 50 from the exhaust passage E1. This collection is performed for a predetermined time such as 1 second. The predetermined time is obtained in advance by experiments and stored in the ROM. When a predetermined time has elapsed from the opening control of the recovery valve 52, the ECU 70 controls the recovery valve 52 to close. In this way, exhaust gas that can contain a reducing component such as HC or CO in a predetermined ratio or a predetermined amount or more is recovered in the container 50.

  Next, emission of exhaust gas will be described. Here, the exhaust gas is released when the pressure in the container 50 is equal to or higher than a second predetermined pressure (for example, a gauge pressure of 1.1 kPa). This is because it is necessary that there is an exhaust gas in an amount that can be discharged into the container 50, and to prevent the backflow of the exhaust gas from the exhaust passage E <b> 2 into the container 50. The ECU 70 determines whether or not the cumulative value of the operation time of the internal combustion engine has exceeded a predetermined time. The accumulated value is the total accumulated time from the engine start to the engine stop, which is cumulatively measured by the time measuring means built in the ECU 70. Once the internal combustion engine 10 is stopped, the cumulative value up to that time is stored in a rewritable manner, and when the internal combustion engine 10 is started again, the cumulative value is further updated by adding the elapsed time. However, the predetermined time compared with the cumulative value of the operation time is a time during which it can be determined that the NOx occlusion amount occluded in the downstream purification unit 46 exceeds the predetermined amount, and is obtained in advance by experiments and stored in the ROM. ing.

  The ECU 70 controls the release valve 60 to open when the pressure in the container 50 is equal to or higher than the second predetermined pressure and the accumulated value of the operation time of the internal combustion engine 10 exceeds the predetermined time. That is, at other times, the ECU 70 outputs an operation signal to the actuator 62 so that the release valve 60 in the closed state is opened. At this time, since the pressure of the exhaust passage 35, that is, the pressure at the communication portion between the discharge passage 56 and the exhaust passage E2 is, for example, 1.05 kPa, the pressure of the exhaust passage E2 is lower than the pressure in the container 50. Therefore, the exhaust gas in the container 50 is released to the exhaust passage E2. This release is performed for a second predetermined time, for example, 1 second. The second predetermined time is a time during which a reducing component sufficient to recover the NOx storage capacity of the downstream purification unit 46 can be supplied to the downstream purification unit 46, and is obtained in advance and stored in the ROM. Has been. When the second predetermined time has elapsed from the valve opening control of the release valve 60, the ECU 70 controls the release valve 60 to close. In this way, the downstream purification unit 46 is supplied with exhaust gas that can contain a reducing component such as HC or CO in a predetermined ratio or amount. Therefore, the NOx occlusion ability of the downstream side purification unit 46 is recovered and NOx can be purified.

  As described above, according to the first embodiment, exhaust gas that can contain a reducing component such as HC or CO in a predetermined ratio (amount) or more is recovered and supplied to the downstream purification unit 46. Thus, it is possible to recover the NOx storage capacity and purify NOx. Therefore, it becomes possible to continuously purify NOx in the exhaust gas using HC, CO, or the like contained in the exhaust gas as a reducing component.

  Next, a second embodiment of the present invention will be described with reference to FIGS. However, the present second embodiment differs from the first embodiment mainly in the installation location of the container and the mounting of the heating mechanism associated therewith, but has substantially the same configuration other than that. Therefore, here, the same (or corresponding) components as those described in the first embodiment are denoted by the same reference numerals as those used above, and the description thereof is omitted. Differences will be described. In the second embodiment, the same control as described in the first embodiment is performed and the same effect is produced, but this description is also omitted.

  As described above, the exhaust passage 35 is defined by the exhaust manifold 40, the exhaust pipe 42, and the like. Here, the container 150 is provided adjacent to the exhaust pipe 42 among those members (exhaust passage defining members) that define the exhaust passage 18. More specifically, the exhaust pipe 42 is provided so as to penetrate the container 150. Such a relationship enables heat exchange between the exhaust passage 35 and the inside of the container 150. That is, the inside of the container 150 can be directly heated using the heat of the exhaust gas flowing through the exhaust passage 35. FIG. 3 shows a partial cross-sectional schematic view of the periphery of the container 150 provided so that the exhaust passage 35 penetrates.

  A space S in the container 150 is defined by an outer wall 102 and a substantially cylindrical inner wall 104 that is also a part of the exhaust pipe 42. The inner wall 104 includes a corrugated portion 106 that has a corrugated or bellows shape so as to increase the surface area in order to promote heat exchange between the exhaust gas in the container 150 and the exhaust gas flowing through the exhaust passage 35. . The waved portion 106 constitutes a heat exchange means. Since a part of the exhaust pipe 42 positioned inside the container 150, that is, the inner wall 104 has such a structure, the heat of the exhaust gas flowing through the exhaust passage 35 is accurately transmitted to the exhaust gas taken into the space in the container 150. can do. That is, the inside of the container 150 can be heated using the heat of the exhaust gas flowing through the exhaust passage 35. Thereby, the pressure and temperature of the gas in the container 150 can rise. The wavy portion 106 also serves to relieve internal thermal stress generated on the inner wall 104.

  Although not provided in the container 150 of the second embodiment, when the pressure in the container 150 exceeds a predetermined upper limit pressure, for example, 300 kPa as a gauge pressure, the valve is automatically opened to reduce the pressure. A safety valve that suppresses the pressure to be equal to or lower than the predetermined upper limit pressure may be provided. The safety valve is preferably configured to exhaust the exhaust gas stored in the container 150 after passing through both the upstream side purification unit 44 and the downstream side purification unit 46. For this purpose, for example, the location of the container 150 is preferably provided adjacent to the exhaust passage defining member on the upstream side of the upstream purification unit 44.

  As described above, since the container 150 or the like has the above-described configuration, the exhaust gas collected and stored in the container 150 can be heated to increase its pressure. Therefore, the pressure of the exhaust gas in the container 150 is more easily and surely made higher than the pressure of the exhaust passage E2 as compared with the pressure of the exhaust gas in the container 50 of the first embodiment. For this reason, the usable period of the exhaust gas in the container 150 is expanded, so that the exhaust gas containing the reducing component in the container 150 can be reliably supplied to the downstream side purification unit 46 at a desired time.

  Next, a third embodiment of the present invention will be described with reference to FIGS. However, the third embodiment has substantially the same configuration as the first embodiment except that an exhaust throttle valve and an actuator therefor are mainly installed in the exhaust passage E2. Therefore, here, the same (or corresponding) components as those described in the first embodiment are denoted by the same reference numerals as those used above, and the description thereof is omitted. Differences will be described. In the third embodiment, the same control as described in the first embodiment is performed and the same effect is obtained, but this description is largely omitted. However, the third embodiment may be provided with a mechanism for heating the exhaust gas in the container with the heat of the exhaust gas flowing through the exhaust passage, as in the second embodiment, but the third embodiment is not so. It is a form which does not have a simple mechanism.

  In the third embodiment, an exhaust throttle valve 202 is provided in the exhaust passage E2. The exhaust throttle valve 202 is provided in the exhaust passage E <b> 2 between the upstream purification unit 44 and the downstream purification unit 46 and in the vicinity of the nozzle 64 of the discharge passage 56. More specifically, the exhaust throttle valve 202 is provided in the vicinity of the upstream side of the nozzle 64 as shown in the enlarged schematic view of FIG. Here, the exhaust throttle valve 202 is a butterfly valve, and is driven by an actuator 204 that is controlled by an operation signal from the ECU 70. In FIG. 5, the position where the exhaust throttle valve 202 is in the open position I in the fully open state is drawn with a dotted line, and the place where it is in the half open position II in the half opened state is drawn with a solid line. As is clear from FIG. 5, the valve body of the exhaust throttle valve 202 is positioned so that the downstream opening 202 d of the exhaust throttle valve 202 in the half-open state II is positioned in the vicinity of the jet outlet of the nozzle 64. Accordingly, one nozzle outlet of the nozzle 64 is positioned in the vicinity of the downstream side of the portion (exhaust passage reducing portion) where the exhaust passage E2 can be reduced (reduced diameter) by the exhaust throttle valve 202. The exhaust throttle valve control means for controlling the opening degree of the exhaust throttle valve 202 includes the actuator 204 and a part of the ECU 70.

  The exhaust throttle valve 202 is normally held in the open state at the open position I. And when exhaust gas is collect | recovered in the container 50 from the exhaust passage E1, it is controlled to the half-open position II. As a result, the pressure of the exhaust passage 35 upstream of the exhaust throttle valve 202 in the exhaust passage 35 is increased, and the exhaust gas having a higher pressure is recovered in the container 50. However, when collecting exhaust gas into the container 50 during acceleration operation, the exhaust throttle valve 202 does not have to be closed in order to prevent a braking force from being generated in the vehicle. When collecting the exhaust gas, the exhaust throttle valve 202 may be fully closed. Note that, when the exhaust throttle valve 202 is controlled to be closed when collecting the exhaust gas, the pressure in the exhaust passage E1 is increased by the closing of the exhaust throttle valve 202. Therefore, this is concerned when the pressure in the container 50 is lower than the first predetermined pressure. Instead, exhaust gas recovery may be performed. In this case, the recovery valve 52 may be opened when the pressure in the container 50 exceeds the pressure in the exhaust passage E1. For this determination, the third embodiment further includes a pressure sensor 206 for detecting the pressure in the exhaust passage upstream of the exhaust throttle valve 202, for example, the exhaust passage E1.

  Further, the exhaust throttle valve 202 is controlled to the half-open position II when exhaust gas is discharged from the container 50 into the exhaust passage E2. However, the case where the exhaust throttle valve 202 is in the half-open position corresponds to the case where the discharge valve 60 is opened. Accordingly, as schematically shown in FIG. 5, the flow of the exhaust gas in the exhaust passage E2 is narrowed by the exhaust throttle valve 202, so that the exhaust passage is near the downstream side of the downstream opening 202d. The flow rate of the exhaust gas flowing through E2 is increased and the pressure is decreased. Accordingly, since one jet port of the nozzle 64 is positioned in the vicinity of the downstream side of the exhaust passage reduction portion formed in the exhaust passage E2, the force for sucking the exhaust gas in the container 50 toward the exhaust passage E2 is increased. It acts on the exhaust gas flowing through. The exhaust gas that has thus reached the exhaust passage E2 from the container 50 is appropriately mixed with the exhaust gas that has passed through the exhaust throttle valve 202. As a result, the exhaust gas supplied from the inside of the container 50, that is, the exhaust gas containing a reducing component such as HC or CO, can be distributed evenly to the downstream purification unit 46. Therefore, the NOx occlusion ability can be recovered more reliably in the entire downstream purification unit 46.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. However, the fourth embodiment is different from the first embodiment in the configuration of the member at the end of the discharge passage 56 on the exhaust passage E2 side, but the other configurations are substantially the same. Therefore, here, the same (or corresponding) components as those described in the first embodiment are denoted by the same reference numerals as those used above, and their description is omitted, and the discharge passage of the fourth embodiment is omitted. The configuration of some of the members on the downstream side 56 and the effects thereof will be described with reference to the schematic diagram of FIG. In the fourth embodiment, the same control as described in the first embodiment is performed and the same effect is produced, but this description is also omitted. However, the fourth embodiment may include a mechanism for heating the exhaust gas in the container 50 with the heat of the exhaust gas flowing through the exhaust passage 35 as in the second embodiment, but the fourth embodiment It is a form without such a mechanism. Further, in the fourth embodiment, as in the third embodiment, the exhaust passage 35 may be provided on the downstream side of the communication portion between the exhaust passage E1 upstream of the upstream purification unit 44 and the recovery passage 47. Although an exhaust throttle valve may be provided, the fourth embodiment is a form in which such a mechanism is not provided.

  As shown in FIG. 6, a spray bar 364 having a plurality of jet ports 364h is provided at the downstream end portion of the discharge passage 56 of the fourth embodiment. That is, the end of the discharge pipe 58 on the side of the exhaust passage E2 extends to the exhaust passage E2, and is the same as the plurality of jet ports 364h provided in the extended portion. The jet outlet 364h may be provided in any direction, but here, it is positioned so as to open toward the upstream side although it is not clear in FIG. As a result, the exhaust gas injected and supplied from the ejection port 364h to the exhaust passage E2 is appropriately mixed with the exhaust gas flowing through the exhaust passage E2. Therefore, similarly to the third embodiment, the exhaust gas supplied from the inside of the container 50, that is, the exhaust gas containing a reducing component such as HC, can reach the downstream purification unit 46 evenly. Therefore, the NOx occlusion ability can be recovered more reliably in the entire downstream purification unit 46.

  As mentioned above, although this invention was demonstrated based on 1st-4th embodiment, this invention is not limited to these. For example, the downstream purification unit 46 may be a catalyst having NOx purification capability, and is not limited to the above configuration. Specifically, the downstream purification unit 46 may be configured to include a selective reduction type NOx catalyst. Further, the timing for recovering the NOx occlusion capacity of the downstream purification unit may be when the NOx occlusion amount cumulatively estimated from the operating state exceeds a predetermined amount.

  In the various embodiments described above, the recovery valve 52 and the discharge valve 60 are poppet valves, but they may be other types of valves, and may be butterfly valves or shutter valves. Note that the recovery valve 52 can be replaced by a check valve. Further, although the exhaust throttle valve 202 is a butterfly valve, other types of valves may be used. The exhaust throttle valve 202 can be, for example, a poppet valve or a shutter valve. As the exhaust throttle valve 202, a valve provided for an exhaust brake may be used.

  In the various embodiments described above, one container 50, 150 is provided, but a plurality of containers 50, 150 may be provided. When two or more containers 50 and 150 are provided, they can be distributed in the vehicle.

  In the various embodiments described above, the present invention is applied to a diesel engine. However, the present invention is not limited to this, and the present invention is not limited to a port injection type gasoline engine and a cylinder injection type gasoline engine. Applicable to internal combustion engines. The fuel used is not limited to light oil or gasoline, but may be alcohol fuel, LPG (liquefied natural gas), or the like. Further, the number of cylinders of the internal combustion engine to which the present invention is applied may be any number.

  Although the present invention has been described with a certain degree of specificity in the first to fourth embodiments and the modifications thereof, the present invention is not deviated from the spirit and scope of the invention described in the claims. It should be understood that various modifications and changes are possible. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents.

1 is a conceptual diagram of an internal combustion engine system for a vehicle to which an exhaust gas purification system of a first embodiment is applied. It is a conceptual diagram of the internal combustion engine system of the vehicle to which the exhaust gas purification system of 2nd Embodiment was applied. It is a partial cross section schematic diagram which expanded and represented the container periphery of FIG. It is a conceptual diagram of the internal combustion engine system of the vehicle to which the exhaust gas purification system of 3rd Embodiment was applied. It is a cross-sectional schematic diagram which expanded and represented the discharge channel downstream edge part vicinity of FIG. It is the cross-sectional schematic diagram which expanded and represented the discharge channel downstream edge part vicinity of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 35 Exhaust passage 44 Upstream side purification | cleaning part 46 Downstream side purification | cleaning part 47 Collection | recovery passages 50 and 150 Container 56 Release passage

Claims (6)

In an exhaust gas purification system comprising an upstream purification unit and a downstream purification unit arranged in series in an exhaust passage of an internal combustion engine, the downstream purification unit including a catalyst having NOx purification capability,
A recovery passage having one end communicated with the exhaust passage on the upstream side of the upstream purification section and provided with a recovery valve;
An exhaust gas container in which the other end of the recovery passage is communicated;
A discharge passage in which one end portion is communicated with the exhaust gas storage container and the other end portion is communicated with an exhaust passage between the upstream purification portion and the downstream purification portion, and a discharge valve is provided;
An exhaust gas purification system comprising: a release valve control means for controlling the opening of the release valve to release exhaust gas containing a reducing component in the exhaust gas storage container.   The exhaust gas purification system according to claim 1, wherein the upstream purification unit is configured to have an oxidation capability or a PM trapping function. A recovery valve control means for controlling the opening of the recovery valve provided in the recovery passage;
The exhaust gas purification system according to claim 1 or 2, wherein the recovery valve control means controls the recovery valve to open when the engine is started or accelerated. Among the exhaust passages of the internal combustion engine, an exhaust throttle valve provided on the downstream side of the communication portion between the exhaust passage upstream of the upstream purification unit and the recovery passage;
Exhaust throttle valve control means for controlling the opening of the exhaust throttle valve,
4. The exhaust gas purification system according to claim 1, wherein the exhaust throttle valve control means controls the exhaust throttle valve to be closed when the engine is started.   The exhaust gas purification system according to any one of claims 1 to 4, wherein one or a plurality of jet outlets are provided at the other end portion of the discharge passage on the exhaust passage side.   6. The exhaust gas purification system according to claim 5, wherein the jet port is located in the vicinity of an exhaust passage reduction portion formed in the exhaust passage between the upstream purification unit and the downstream purification unit. .

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