JP5981240B2 - Exhaust purification equipment - Google Patents

Description

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

  Conventionally, in an exhaust pipe of a vehicle equipped with an internal combustion engine, a NOx occlusion reduction type catalyst that occludes nitrogen oxide (NOx) contained in exhaust gas, or a particulate filter (hereinafter referred to as PM) that captures PM (Particulate Matter). A PM filter).

  When the NOx occlusion amount increases due to use of the NOx occlusion reduction catalyst, the processing capacity as the catalyst decreases. Therefore, it is necessary to perform a regeneration process for decomposing NOx stored by the NOx storage reduction catalyst and regenerating the processing capacity of the catalyst. As a countermeasure, an internal combustion engine having an exhaust purification device having this regeneration processing function has been developed (see, for example, Patent Document 1).

  In this type of exhaust purification device, a reducing agent injection valve opened to the exhaust port is provided, and a reducing agent such as fuel discharged by a fuel pump is injected from the reducing agent injection valve to the exhaust port. The reducing agent injected into the exhaust port is mixed with the exhaust gas and supplied to the NOx storage reduction catalyst. According to this exhaust purification device, NOx occluded in the NOx occlusion reduction type catalyst is purified by the reducing agent, and the processing capacity as the catalyst is regenerated, so that the NOx reduction ability of the exhaust gas is reduced even when used for a long period of time. Can be suppressed.

  On the other hand, the PM filter needs to be appropriately regenerated because PM accumulates inside and increases the passage resistance. As a regeneration process, for example, a method has been proposed in which a hydrocarbon-based liquid such as fuel is introduced into a PM filter to cause an exothermic reaction, and PM is burned off by the generated heat. Therefore, by using the above-described exhaust purification device, fuel can be caused to flow into the PM filter as a reducing agent, so that regeneration processing can also be realized in the PM filter.

JP 2001-280125 A

  However, in the conventional exhaust purification device, the nozzle of the reducing agent injection valve is exposed to the exhaust port. For this reason, the nozzle is exposed to high temperature exhaust gas, and the temperature at the tip of the nozzle becomes relatively high. Therefore, deposits may gradually accumulate on the nozzle and its surroundings, causing clogging of the nozzle, etc. There was a problem that there was.

  Specifically, since the temperature at the tip of the nozzle is relatively high, when the reducing agent injected from the nozzle adheres to the tip of the nozzle, the volatile component of the attached reducing agent evaporates and the remaining component is altered. Then, it gradually accumulates as a deposit. Further, when the attached reducing agent acts as a binder, smoke composed of soot or the like in the exhaust gas adheres and gradually deposits as a deposit. When deposits are accumulated at the tip of the nozzle, the nozzle is clogged, and there is a problem that the reducing agent may not be satisfactorily supplied to the exhaust passage.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an exhaust purification device capable of suppressing deposit accumulation on a nozzle of a reducing agent injection valve as compared with the conventional one.

In order to achieve the above object, an exhaust emission control apparatus according to the present invention includes (1) a catalyst provided in an exhaust pipe of an internal combustion engine for purifying exhaust gas, and a nozzle for injecting a reducing agent into the exhaust pipe upstream of the catalyst. And a support member for supporting the reducing agent injection valve with respect to the exhaust pipe, and adding the reducing agent to the exhaust gas from the reducing agent injection valve. The exhaust purifying apparatus recovering the function, wherein the support member communicates from a nozzle accommodating portion that accommodates at least a part of the nozzle to the exhaust pipe and from a front end surface of the nozzle. located above direction, and a shroud portion having a hole of inner diameter less than the inner diameter of the nozzle housing portion, while gap is provided between the nozzle and the shroud portion, the axis of the nozzle The configure so that decentered in the upstream direction of the flow of exhaust gases with respect to the axis of the nozzle housing portion.

  According to the configuration of the present invention, the shroud portion located in the forward direction from the tip surface of the nozzle has a through-hole having an inner diameter smaller than the inner diameter of the nozzle housing portion, so that compared with the conventional case without the shroud portion. , Exhaust gas is difficult to hit the nozzle. For this reason, heating of the nozzle can be suppressed as compared with the prior art. Since the temperature of the nozzle is suppressed, it is possible to suppress the accumulation of deposits resulting from the high temperature of the tip portion of the nozzle and to suppress the occurrence of clogging of the nozzle.

In addition, since a gap is provided between the nozzle and the shroud portion, for example, when a sealing material is provided between the reducing agent injection valve and the support member, the reducing agent injection valve and the support member Even if the sealing material is strongly pressed and deformed, the nozzle and the shroud portion do not interfere with each other. For this reason, since the sealing material can be firmly pressed by the reducing agent injection valve and the support member, the sealing performance of the sealing material can be improved. Alternatively, even when a sealant is not provided between the reducing agent injection valve and the support member, the reduction agent injection valve and the support member are strengthened by providing a gap between the nozzle and the shroud portion. Since the contact can be made, the sealing property between the reducing agent injection valve and the support member can be improved. Further, with this configuration, the nozzle axis is eccentric in the upstream direction of the exhaust gas flow with respect to the axis of the nozzle accommodating part, so that the nozzle axis coincides with the axis of the nozzle accommodating part. In comparison, it is possible to reduce the flow rate of the exhaust gas blown from the exhaust pipe into the through hole of the shroud portion. As a result, the nozzle is less likely to be heated, so that the nozzle is prevented from being heated to a high temperature, deposit accumulation due to the high temperature of the nozzle tip is suppressed, and clogging of the nozzle is suppressed. be able to.

  Here, if the gap between the nozzle and the shroud portion is reduced, the flow rate of the exhaust gas flowing through the gap and entering the inside of the shroud portion can be reduced, so that an increase in nozzle temperature can be suppressed. Accordingly, the size of the gap is preferably set to a predetermined value or less.

In the exhaust emission control device according to (1 ) , ( 2 ) the inner diameter of the through hole of the shroud portion is configured to be smaller than the outer diameter of the nozzle. With this configuration, since a part of the tip surface of the nozzle is covered with the shroud portion, the flow rate at which the exhaust gas that has entered the through hole of the shroud portion from the exhaust pipe hits the nozzle can be reduced. As a result, the nozzle is less likely to be heated, so that the nozzle is prevented from being heated to a high temperature, deposit accumulation due to the high temperature of the nozzle tip is suppressed, and clogging of the nozzle is suppressed. be able to.

In the exhaust emission control device described in (1 ) above, ( 3 ) the shroud portion is configured to cover a part of the tip surface of the nozzle. With this configuration, since a part of the tip surface of the nozzle is covered with the shroud portion, the flow rate at which the exhaust gas that has entered the through hole of the shroud portion from the exhaust pipe hits the nozzle can be reduced. As a result, the nozzle is less likely to be heated, so that the nozzle is prevented from being heated to a high temperature, deposit accumulation due to the high temperature of the nozzle tip is suppressed, and clogging of the nozzle is suppressed. be able to.

In the exhaust emission control device according to the above (1) to ( 3 ), ( 4 ) the injection direction of the nozzle is configured to be downstream in the flow direction of the exhaust gas. With this configuration, it is possible to reduce the amount of the reducing agent blown off by the exhaust gas that has entered the through hole of the shroud portion from the exhaust pipe. Thereby, since the quantity of the reducing agent adhering to the front-end | tip part of a nozzle can be reduced, the quantity of the reducing agent adhering to the through-hole of a shroud part and the nozzle hole of a nozzle can be reduced. For this reason, according to the present invention, deposit accumulation can be suppressed and occurrence of nozzle clogging or the like can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust gas purification apparatus which can suppress deposit accumulation to the nozzle of a reducing agent injection valve more than before can be provided.

1 is a schematic view showing an internal combustion engine equipped with an exhaust emission control device according to an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the reducing agent injection valve and attachment of the exhaust gas purification apparatus which concern on embodiment of this invention. It is a longitudinal cross-sectional view which shows the nozzle of the reducing agent injection valve of the exhaust gas purification apparatus which concerns on embodiment of this invention. It is the expanded longitudinal cross-sectional view which shows the reducing agent injection valve and attachment of the exhaust gas purification apparatus which concern on embodiment of this invention. It is the schematic which shows ECU of the internal combustion engine by which the exhaust gas purification apparatus which concerns on embodiment of this invention is mounted. The longitudinal cross-sectional view which shows the modification which the shaft center of the nozzle of the reducing agent injection valve of the exhaust gas purification apparatus which concerns on embodiment of this invention is eccentric to the flow direction downstream of exhaust gas with respect to the shaft center of the shroud part of an attachment. It is. The enlarged longitudinal section which shows the modification in which the axial center of the nozzle of the reducing agent injection valve of the exhaust gas purification device according to the embodiment of the present invention is eccentric to the downstream side in the exhaust gas flow direction with respect to the axial center of the shroud portion of the attachment FIG. It is a longitudinal cross-sectional view which shows the reducing agent injection valve and attachment of the conventional exhaust gas purification apparatus as a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, a case will be described in which the exhaust emission control device according to the present invention is mounted on an in-line four-cylinder diesel engine (hereinafter simply referred to as an engine) 1 as an internal combustion engine. However, the internal combustion engine is not limited to a diesel engine, and may be a gasoline engine.

  First, the configuration will be described.

  As shown in FIG. 1, an engine 1 includes an engine body 2, an intake device 3, an exhaust device 4, an exhaust purification device 5, a turbocharger 6, an EGR (Exhaust Gas Recirculation) device 7, a fuel A supply device 8 and an ECU (Electronic Control Unit) 9 are provided.

  The engine body 2 includes a cylinder head 20 and a cylinder block (not shown). The cylinder head 20 and the cylinder block are provided with four cylinders 21. Each cylinder 21 has a combustion chamber 21a defined by a piston (not shown). The engine body 2 is configured to reciprocate a piston by burning a mixture of fuel and air at a desired timing in a combustion chamber 21a and rotate a crankshaft (not shown).

  The intake device 3 includes an intake port pipe 30, an air cleaner 31, an intake pipe 32, an air flow meter 33, an intercooler 34, a throttle valve 35, a throttle sensor 36, and an intake manifold 37.

  The air cleaner 31 is cleaned by removing dust and the like from the intake air A by a built-in filter at an upstream portion of the intake device 3. The intake pipe 32 is connected from the air cleaner 31 to the intake manifold 37 with the turbocharger 6 interposed therebetween. The air flow meter 33 detects the flow rate of the intake air A and inputs it to the ECU 9.

  The intercooler 34 is provided in the intake pipe 32 on the downstream side of the turbocharger 6. The intercooler 34 cools the intake air A that has been heated by compression and supercharging in the turbocharger 6.

  The throttle valve 35 is provided between the intercooler 34 and the intake manifold 37 and adjusts the amount of intake air supplied to each cylinder 21 by an electronic control method. The throttle valve 35 is provided with a throttle motor 35a that can control the opening of the throttle valve 35 (hereinafter referred to as the throttle opening). The throttle motor 35a is connected to the ECU 9 and changes the throttle opening in accordance with an instruction from the ECU 9. The throttle sensor 36 is connected to the ECU 9 and detects the throttle opening and inputs it to the ECU 9.

  The intake manifold 37 connects the intake pipe 32 and each cylinder 21. The engine body 2 and the intake device 3 are connected by the connection of the intake manifold 37 and each cylinder 21. An intake valve (not shown) for controlling the flow rate of intake air A introduced into each combustion chamber 21a is provided between the intake manifold 37 and each cylinder 21. The intake air A sucked into the intake manifold 37 is introduced into the combustion chamber 21a when the intake valve is opened according to the rotation angle of a crankshaft (not shown).

  The exhaust device 4 includes an exhaust manifold 40, an exhaust pipe 41, an exhaust temperature sensor 43, a tail pipe 45, and an air / fuel ratio sensor 46.

  The exhaust manifold 40 circulates the exhaust gas G discharged from each cylinder 21. The engine body 2 and the exhaust device 4 are connected by the connection between the exhaust manifold 40 and each cylinder 21. Between the exhaust manifold 40 and each cylinder 21, an exhaust valve (not shown) for controlling the flow rate of the exhaust gas G discharged from each combustion chamber 21a is provided. The exhaust gas G generated in each combustion chamber 21a is exhausted to the exhaust manifold 40 when the exhaust valve is opened according to the rotation angle of a crankshaft (not shown). The exhaust pipe 41 is connected from the exhaust manifold 40 to the tail pipe 45 with the turbocharger 6 and the exhaust purification device 5 interposed therebetween.

  The tail pipe 45 is connected to the downstream side of the exhaust purification device 5. The downstream end of the tail pipe 45 is open to the atmosphere. For this reason, the exhaust gas G that has passed through the exhaust purification device 5 is discharged to the atmosphere via the tail pipe 45.

  The exhaust temperature sensor 43 is provided on the upstream side of the exhaust purification device 5 and on the downstream side of the turbocharger 6 and is connected to the ECU 9, and detects the temperature of the exhaust gas G and inputs it to the ECU 9. ing. The air-fuel ratio sensor 46 is provided on the downstream side of the exhaust purification device 5 and connected to the ECU 9, and detects the oxygen concentration of the exhaust gas G and inputs it to the ECU 9. The air-fuel ratio sensor 46 includes a detection element such as a zirconia element, and detects the oxygen concentration of the exhaust gas G by detecting electric power according to the oxygen concentration difference.

  The exhaust emission control device 5 includes an exhaust aftertreatment device 50 as a catalyst, a reducing agent injection valve 51, and an attachment 52 as a support member. The exhaust emission control device 5 recovers the function of the exhaust after-treatment device 50 by adding a reducing agent to the exhaust gas G from the reducing agent injection valve 51.

  The exhaust after-treatment device 50 includes a catalytic converter 53 and a catalyst-carrying type PM filter 54, and is provided in the exhaust pipe 41 of the engine 1 to purify the exhaust gas G. The configuration of the exhaust after-treatment device 50 is not particularly limited, and a known or new one can be used.

  The catalytic converter 53 is composed of a NOx occlusion-type NOx catalyst. When the exhaust gas G in the lean state of the air-fuel ratio circulates inside, the catalytic converter 53 occludes NOx contained in the exhaust gas G. . Further, when the exhaust gas G in the state where the air-fuel ratio is rich circulates, the catalytic converter 53 causes the stored NOx to react with hydrocarbons or carbon monoxide contained in the exhaust gas G, so that nitrogen, carbon dioxide, The exhaust gas G is purified by decomposing it into water.

  The PM filter 54 is configured by a monolith type or pellet type filter, and collects particulates contained in the exhaust gas G. The PM filter 54 is also provided with the above-described storage-type NOx catalyst, and the PM trapped by the PM filter 54 is oxidized and removed by the oxidizing action of the catalyst.

  As shown in FIGS. 2 and 3, the reducing agent injection valve 51 is provided in the exhaust pipe 41 upstream of the exhaust after-treatment device 50 and downstream of the turbocharger 6, and includes a holder 100, a nozzle body 101, and the like. The needle valve 102 and a core and an electromagnetic coil (not shown) are provided. As the reducing agent injection valve 51 here, a known or new appropriate fuel supply valve used as an electromagnetic fuel supply valve can be applied.

  The holder 100 has a substantially cylindrical shape, and has a nozzle part 100a at the tip and a step part 100b continuous to the base end side of the nozzle part 100a. A nozzle body 101 is accommodated in the nozzle portion 100a. The nozzle portion 100a and the nozzle body 101 are collectively referred to as a nozzle 103. That is, the reducing agent injection valve 51 has a nozzle 103 that injects the reducing agent into the exhaust pipe 41 upstream of the exhaust after-treatment device 50. A base end side (not shown) of the holder 100 is connected to the fuel supply device 8 so that fuel as a reducing agent is supplied into the holder 100.

  The nozzle body 101 includes a substantially conical tip portion 101a and a nozzle hole 101b formed in the tip portion 101a. The injection hole 101b can inject the reducing agent supplied to the inside of the holder 100. The nozzle hole 101b is formed to face the downstream side rather than perpendicular to the flow direction of the exhaust gas G. As a result, it is possible to suppress the fuel injected from the nozzle hole 101b from being ejected back by the exhaust gas G and adhering to the front end surface 103a of the nozzle 103 and its periphery, thereby suppressing deposit accumulation at that portion. Can do.

  The needle valve 102 includes a valve body portion 102a formed at the tip and a guide portion 102b formed in the vicinity of the valve body portion 102a. The valve body portion 102 a and the guide portion 102 b of the needle valve 102 are slidable inside the nozzle body 101. The leading end surface of the valve body 102a closes the injection hole 101b from the inside, so that the reducing agent supplied into the holder 100 is not injected from the injection hole 101b. Moreover, the reducing agent supplied to the inside of the holder 100 is injected from the nozzle hole 101b by separating the tip surface of the valve body 102a from the nozzle hole 101b.

  A core is coupled to the proximal end side of the needle valve 102. The electromagnetic coil is provided in the holder 100 around the core and is connected to the ECU 9. When the electromagnetic coil is energized, the core is adsorbed, and the needle valve 102 slides to switch the open / close state of the nozzle hole 101b.

  The attachment 52 is fixed to the exhaust pipe 41 with, for example, bolts and supports the reducing agent injection valve 51 with respect to the exhaust pipe 41. The attachment 52 is cooled by cooling water using a water cooling mechanism (not shown). As the structure for mounting the reducing agent injection valve 51 of the attachment 52, a known or new appropriate structure can be used.

  In the present embodiment, the attachment 52 includes a stepped portion accommodating portion 110 that accommodates the stepped portion 100b of the holder 100, a nozzle accommodating portion 111 that accommodates at least a part of the nozzle portion 100a, and a shroud portion 112. Yes. Between the end surfaces of the stepped portion 100b and the stepped portion accommodating portion 110, a metal gasket 120 is interposed as a sealing material. The reducing agent injection valve 51 is pressed against the attachment 52 in the axial direction. Thereby, since the step part 100b and the step part accommodating part 110 press on both sides of the metal gasket 120, the sealing performance in the metal gasket 120 can be improved.

  The shroud portion 112 communicates from the nozzle housing portion 111 to the exhaust pipe 41 and is positioned in the forward direction with respect to the tip surface 103 a of the nozzle 103. Further, the shroud portion 112 has a through hole 112 a having an inner diameter smaller than the inner diameter of the nozzle housing portion 111, and the through hole 112 a is provided so as to communicate with an opening 41 a formed in the exhaust pipe 41. .

  In the present embodiment, the inner diameter of the through hole 112a is made smaller than the outer diameter of the nozzle portion 100a. Further, the axial center C2 of the shroud portion 112 and the axial center of the through hole 112a coincide. Further, the through-hole 112a has a circular cross section, for example. For this reason, since the shroud part 112 is located ahead of the front end surface 103 a of the nozzle 103, the exhaust gas G from the exhaust pipe 41 is difficult to hit the nozzle 103, and the high temperature of the nozzle 103 is suppressed. . Further, the tip end portion 101a of the nozzle body 101 enters the inside of the through hole 112a, and the injection hole 101b is positioned.

  A gap S is provided between the nozzle 103 and the shroud portion 112. Thereby, even if the metal gasket 120 is firmly pressed and deformed by the reducing agent injection valve 51 and the attachment 52, the nozzle 103 and the shroud portion 112 do not interfere with each other. For this reason, since the metal gasket 120 can be firmly pressed by the reducing agent injection valve 51 and the attachment 52, the sealing performance of the metal gasket 120 can be improved.

  Here, if the gap S is too large, the exhaust gas G tends to flow into the nozzle accommodating portion 111 from the through-hole 112a. However, if the gap S is too small, the nozzle 103 and the shroud portion 112 come into contact with each other due to an assembly error, thermal expansion, or the like, and the metal gasket 120 cannot be sufficiently pressed by the reducing agent injection valve 51 and the attachment 52. There is a possibility that the sealing performance of the gasket 120 is lowered.

  Therefore, as the size of the gap S, for example, as shown in FIG. 4, the smallest gap S in the axial direction is S1, the smallest gap S in the oblique direction is S2, and the smallest gap S in the radial direction is S3. In this case, it is preferable that all of S1, S2, and S3 are 0.15 mm or more and 1 mm or less. In particular, S1 and S2 are more preferably 0.15 mm or more and 0.5 mm or less. However, as a matter of course, the value of the gap S is not limited to these values.

  Furthermore, the axial center C1 of the nozzle 103 is provided eccentric to the upstream side in the flow direction of the exhaust gas G with respect to the axial center C2 of the shroud portion 112. Thereby, compared with the case where the axial center C1 of the nozzle 103 and the axial center C2 of the shroud portion 112 coincide with each other (see FIG. 8), the exhaust gas G that has entered the through hole 112a of the shroud portion 112 from the exhaust pipe 41 The flow rate which blows to 103 can be reduced.

  The magnitude D of the eccentricity between the axis C1 of the nozzle 103 and the axis C2 of the shroud 112 is preferably large because the effect of reducing the flow rate at which the exhaust gas G blows against the nozzle 103 is small if it is too small. However, if the eccentricity D is too large, the nozzle 103 and the shroud portion 112 may come into contact with each other. Therefore, the eccentric size D is preferably set to 0.15 mm to 0.5 mm, for example. Of course, the value D of the eccentricity D is not limited to these values.

  As shown in FIG. 1, the turbocharger 6 includes an intake air compressor 60 and an exhaust turbine 61. The intake air compressor 60 is provided in the intake pipe 32. The exhaust turbine 61 is provided in the exhaust pipe 41. The intake air compressor 60 and the exhaust turbine 61 are coupled by a rotating shaft 63 and rotate integrally.

  As the exhaust gas G flows through the exhaust pipe 41, the exhaust turbine 61 is rotated. The intake air compressor 60 is rotated by the rotation of the exhaust turbine 61. Further, the intake air A is compressed by the rotation of the intake air compressor 60, and positive pressure air is supplied to the cylinder 21.

  The EGR device 7 includes a communication pipe 70 that communicates from the exhaust manifold 40 to the intake manifold 37, an EGR cooler 71 that is disposed in the middle of the communication pipe 70, and an electric EGR valve 72. In the EGR device 7, a part of the exhaust gas G discharged to the exhaust manifold 40 is cooled by the EGR cooler 71 and recirculated to the intake manifold 37. Further, the ECU 9 controls the amount of exhaust gas recirculated by controlling the opening degree of the EGR valve 72. When the exhaust gas G is recirculated to the combustion chamber 21a, the combustion temperature of the air-fuel mixture in the combustion chamber 21a decreases, and the amount of NOx generated is reduced.

  The fuel supply device 8 includes a fuel tank 80, a fuel filter 81, a low pressure fuel pump 82, a fuel pressure regulator 83, a main fuel pipe 84, a high pressure fuel pump 85, a common rail 86, and a fuel injection valve 87. I have.

  The fuel tank 80 is configured to store a hydrocarbon-based fuel such as light oil, and is constituted by a known fuel tank made of metal or synthetic resin that has been rust-proofed inside. The low pressure fuel pump 82 sucks fuel stored in the fuel tank 80 via the fuel filter 81 and pumps it to the fuel pressure regulator 83. The fuel pressure regulator 83 returns a part of the fuel discharged from the low-pressure fuel pump 82 to the fuel tank 80 when the pressure of the fuel discharged from the low-pressure fuel pump 82, that is, the fuel pressure becomes higher than a predetermined set value. It is like that. The main fuel pipe 84 connects the fuel pressure regulator 83 to the high pressure fuel pump 85.

  The high pressure fuel pump 85 discharges fuel supplied from the fuel pressure regulator 83 as high pressure fuel. The common rail 86 is connected to a high-pressure fuel pump 85 and stores high-pressure fuel supplied from the high-pressure fuel pump 85.

  The fuel injection valve 87 is connected to the common rail 86 and is installed in the cylinder head 20 corresponding to each cylinder 21. The fuel injection valve 87 injects the fuel supplied from the common rail 86 into each combustion chamber 21a. That is, the high-pressure fuel supplied from the high-pressure fuel pump 85 to the common rail 86 is injected from the fuel injection valve 87 into the corresponding combustion chamber 21a by opening the fuel injection valve 87 based on the rotation angle of the crankshaft. Yes.

  A branch pipe 84 a is provided in the main fuel pipe 84 between the fuel pressure regulator 83 and the high pressure fuel pump 85. The branch pipe 84 a is connected to the reducing agent injection valve 51 of the exhaust purification device 5, and supplies a part of the fuel discharged from the low pressure fuel pump 82 to the exhaust purification device 5.

  As shown in FIG. 5, the ECU 9 includes a CPU (Central Processing Unit) 9a, a RAM (Random Access Memory) 9b, a ROM (Read Only Memory) 9c, and an EEPROM connected to each other via a bidirectional bus. (Electrically Erasable and Programmable Read Only Memory (registered trademark)) 9d, a microcomputer having an input port 9e and an output port 9f.

  The CPU 9a uses the temporary storage function of the RAM 9b to perform signal processing in accordance with a program stored in advance in the ROM 9c and data stored in the EEPROM 9d, thereby performing various controls such as output control of the engine 1 and catalyst function recovery control described later. Control is to be executed.

  An air flow meter 33, a throttle sensor 36, an exhaust gas temperature sensor 43, and an air-fuel ratio sensor 46 are connected to the input port 9e of the ECU 9. Information detected by these sensors is taken into the ECU 9.

  A throttle motor 35a, an EGR valve 72, a low pressure fuel pump 82, a reducing agent injection valve 51, a high pressure fuel pump 85, and a fuel injection valve 87 are connected to the output port 9f of the ECU 9. The ECU 9 executes operation control of the engine 1, for example, opening degree control of the throttle valve 35, the EGR valve 72, and the like.

  Next, the operation will be described.

  When the engine 1 is in operation, fuel is supplied as a reducing agent to the reducing agent injection valve 51 by the fuel supply device 8. The ECU 9 does not energize the electromagnetic coil of the reducing agent injection valve 51 during normal engine operation when it is determined that the reducing agent should not be injected from the reducing agent injection valve 51. For this reason, in the reducing agent injection valve 51, since the valve body portion 102a of the needle valve 102 closes the injection hole 101b from the inside, the reducing agent is not injected from the injection hole 101b.

  The ECU 9 determines whether or not the function of the exhaust after-treatment device 50 as a catalyst has deteriorated based on, for example, travel time, travel distance, or other operating conditions. When the ECU 9 determines that the function of the exhaust after-treatment device 50 as a catalyst has deteriorated, the ECU 9 appropriately sets the timing, the injection amount, and the injection time for injecting the reducing agent from the reducing agent injection valve 51. Then, the ECU 9 energizes the electromagnetic coil of the reducing agent injection valve 51 for a predetermined time. For this reason, in the reducing agent injection valve 51, the needle valve 102 slides and the valve body portion 102a opens the injection hole 101b, so that the reducing agent is injected from the injection hole 101b.

  Here, since the through-hole 112a of the shroud portion 112 positioned in the forward direction of the tip surface 103a of the nozzle 103 has an inner diameter smaller than the outer diameter of the nozzle 103, the exhaust gas G is difficult to hit the nozzle 103. In addition, since the gap S is provided between the nozzle 103 and the shroud portion 112, heat transfer from the shroud portion 112 to the nozzle 103 can be significantly suppressed. For these reasons, heating of the nozzle 103 is suppressed.

  Then, the reducing agent is injected into the exhaust gas G, and the reducing agent is added to the exhaust aftertreatment device 50 disposed on the downstream side thereof. Therefore, the function of the exhaust aftertreatment device 50 as a catalyst is restored. In addition, the ECU 9 stops the injection of the reducing agent by stopping the energization of the electromagnetic coil of the reducing agent injection valve 51 and closing the reducing agent injection valve 51 again after performing the injection of the reducing agent for a predetermined time. .

  As described above, according to the exhaust gas purification apparatus 5 according to the present embodiment, the inner diameter of the through hole 112a of the shroud portion 112 positioned in the forward direction from the tip surface 103a of the nozzle 103 is smaller than the outer diameter of the nozzle 103. Therefore, it becomes difficult for the exhaust gas G to hit the nozzle 103. Thereby, since heating of the nozzle 103 is suppressed, deposit accumulation resulting from the high temperature of the tip portion of the nozzle 103 can be suppressed, and occurrence of clogging of the nozzle 103 or the like can be suppressed.

  Further, since the gap S is provided between the nozzle 103 and the shroud portion 112, the nozzle 103 and the shroud portion 112 can be deformed even if the metal gasket 120 is firmly pressed and deformed by the reducing agent injection valve 51 and the attachment 52. Does not interfere with. For this reason, since the metal gasket 120 can be firmly pressed by the reducing agent injection valve 51 and the attachment 52, the sealing performance of the metal gasket 120 can be improved.

  Further, according to the exhaust purification device 5 according to the present embodiment, the axis C1 of the nozzle 103 is eccentric to the upstream side in the flow direction of the exhaust gas G with respect to the axis C2 of the shroud portion 112. For this reason, compared with the case where the axial center C1 of the nozzle 103 and the axial center C2 of the shroud part 112 coincide, the flow rate at which the exhaust gas G that has entered the through hole 112a of the shroud part 112 from the exhaust pipe 41 blows to the nozzle 103. Can be reduced. As a result, the nozzle 103 is less likely to be heated, so that the nozzle 103 is prevented from being heated to a high temperature, deposit accumulation resulting from the high temperature at the tip of the nozzle 103 is suppressed, and the nozzle 103 is clogged. Occurrence can be suppressed.

  Further, according to the exhaust purification device 5 according to the present embodiment, the direction of the injection hole 101b, that is, the injection direction of the reducing agent from the nozzle 103 is on the downstream side in the flow direction of the exhaust gas G. For this reason, the quantity of the reducing agent blown off by the exhaust gas G which entered the through-hole 112a of the shroud part 112 from the exhaust pipe 41 can be reduced. Thereby, since the amount of reducing agent adhering to the tip portion of the nozzle 103 can be reduced, the amount of reducing agent adhering to the through hole 112a of the shroud portion 112 and the nozzle hole 101b of the nozzle 103 can be reduced. For this reason, according to this exhaust gas purification apparatus 5, deposit accumulation can be suppressed and occurrence of clogging of the nozzle 103 or the like can be suppressed.

  In the exhaust purification apparatus 5 of the present embodiment described above, the case where the axial center C1 of the nozzle 103 is eccentric to the upstream side in the flow direction of the exhaust gas G with respect to the axial center C2 of the shroud portion 112 is described. However, the exhaust gas purification apparatus according to the present invention is not limited to this. For example, as shown in FIGS. 6 and 7, the shaft center C <b> 1 of the nozzle 103 is less than the shaft center C <b> 2 of the shroud portion 112. It may be eccentric to the downstream side in the flow direction.

  Also in this case, the flow rate at which the exhaust gas G entering the through-hole 112a of the shroud 112 from the exhaust pipe 41 blows to the nozzle 103 can be reduced, so that the nozzle 103 becomes difficult to be heated and the nozzle 103 becomes high temperature. It is suppressed. Therefore, as in the case where the axial center C1 of the nozzle 103 is eccentric to the upstream side in the flow direction of the exhaust gas G with respect to the axial center C2 of the shroud portion 112, the deposit resulting from the high temperature of the tip of the nozzle 103 is deposited. And the occurrence of clogging of the nozzle 103 can be suppressed. That is, according to the exhaust purification device 5 of the present embodiment, the same effect can be obtained on both the upstream side and the downstream side as long as the eccentric direction between the nozzle 103 and the shroud portion 112 is the exhaust gas flow direction.

  Alternatively, the axial center C1 of the nozzle 103 and the axial center C2 of the shroud portion 112 are eccentric in a direction orthogonal to the flow direction of the exhaust gas, or the axial center C1 of the nozzle 103 and the axial center C2 of the shroud portion 112 May match.

  Further, in the above-described exhaust purification device 5 of the present embodiment, the case where the inner diameter of the through hole 112a of the shroud portion 112 is smaller than the outer diameter of the nozzle 103 is described. However, the exhaust purification apparatus according to the present invention is not limited to this, and it is sufficient that the inner diameter of the through hole 112a of the shroud portion 112 is at least smaller than the inner diameter of the nozzle housing portion 111. Since the inner diameter of the through-hole 112a is smaller than the inner diameter of the nozzle housing portion 111, a part of the tip end surface 103a of the nozzle 103 is covered with the shroud portion 112, and thus enters the through-hole 112a of the shroud portion 112 from the exhaust pipe 41. The flow rate at which the exhaust gas G blows against the nozzle 103 can be reduced.

  Moreover, in the exhaust purification apparatus 5 of this Embodiment mentioned above, the case where the through-hole 112a of the shroud part 112 is circular in cross section is demonstrated. However, the exhaust purification apparatus according to the present invention is not limited to this, and the shroud portion 112 may be configured to cover a part of the tip surface 103a of the nozzle 103 with a shape other than a circular cross section.

  Further, in the above-described exhaust purification device 5 of the present embodiment, the case where the injection direction of the nozzle 103 is on the downstream side in the flow direction of the exhaust gas G is described. However, the exhaust gas purification apparatus according to the present invention is not limited to this, and the injection direction of the nozzle 103 may be a direction perpendicular to the flow direction of the exhaust gas G or an upstream side. In this case, the reducing agent is directed so as not to hit the shroud portion 112 directly.

  Moreover, in the exhaust purification apparatus 5 of this Embodiment mentioned above, the case where the metal gasket 120 is interposed between the end surfaces of the step part 100b and the step part accommodating part 110 is demonstrated. However, the exhaust purification apparatus according to the present invention is not limited to this, and the installation position of the metal gasket 120 may be another position, or a member other than the metal gasket 120 may be applied as a sealing material. . Furthermore, this type of sealing material is not necessarily used depending on the configuration.

  Further, in the above-described exhaust purification device 5 of the present embodiment, the case where the shroud portion 112 is integrated with the attachment 52 has been described. However, the exhaust purification apparatus according to the present invention is not limited to this, and the shroud portion 112 and the attachment 52 may be separate members. In this case, the shroud portion 112 is integrated with the attachment 52 by a method such as fitting, welding, or screwing.

  Moreover, in the exhaust purification apparatus 5 of this Embodiment mentioned above, the case where the attachment 52 is attached to the exhaust pipe 41 by bolting is demonstrated. However, the exhaust emission control device according to the present invention is not limited to this, and the attachment and the exhaust pipe may be integrally formed.

  Further, in the above-described exhaust purification device 5 of the present embodiment, the case where the reducing agent injection valve 51 is installed in the exhaust pipe 41 near the upstream side of the exhaust after-treatment device 50 is described. However, the exhaust gas purification apparatus according to the present invention is not limited to this, and the reducing agent injection valve 51 may be directly attached to the cylinder head 20 to inject the reducing agent into the exhaust port. In this case, the attachment is the cylinder head 20.

  Moreover, in the exhaust purification apparatus 5 of this Embodiment mentioned above, the case where fuel is injected as a reducing agent from the reducing agent injection valve 51 is demonstrated. However, the exhaust gas purification apparatus according to the present invention is not limited to this, and urea may be applied as a reducing agent.

  Further, in the above-described exhaust purification device 5 of the present embodiment, the case where the engine 1 includes the turbocharger 6 and the EGR device 7 is described. However, the exhaust gas purification apparatus according to the present invention is not limited to this, and the engine 1 may not include the turbocharger 6 and the EGR device 7.

  As described above, the exhaust gas purification apparatus according to the present invention has an effect that deposit accumulation on the nozzle of the reducing agent injection valve can be suppressed as compared with the conventional one, and is useful for the exhaust gas purification apparatus.

  The engine 1 was operated, and the temperature of the nozzle 103 of the exhaust gas purification device 5 and its surroundings and the flow rate of the exhaust gas G were measured.

(Example)
As shown in FIG. 4, the reducing agent injection valve 51 is supported by the exhaust pipe 41 by the attachment 52 of the present embodiment described above. As a result, the temperature at the tip 101a of the nozzle body 101 was 200 ° C., the temperature at P1 was 320 ° C., and the flow rate of the exhaust gas G at P1 was 20 m / s.

(Comparative example)
As shown in FIG. 8, the reducing agent injection valve 51 is supported on the exhaust pipe 41 by an attachment 152 that does not have the shroud portion 112 as in the conventional case. The operating conditions of the reducing agent injection valve 51 and the engine 1 were the same as those in the comparative example. The measurement point P2 was a position corresponding to P1 in the example. As a result, the temperature at the tip 101a of the nozzle body 101 was 270 ° C., the temperature at P2 was 405 ° C., and the flow rate of the exhaust gas G at P2 was 96 m / s.

  Therefore, by providing the shroud portion 112, the temperature at the tip end portion 101a of the nozzle body 101 is greatly reduced. Further, by providing the shroud portion 112, the flow rate of the exhaust gas G at P1 is significantly slowed down, and the temperature at P1 is also greatly reduced. Therefore, it was confirmed that the high temperature of the nozzle 103 can be suppressed by providing the shroud portion 112 as in the present embodiment.

1 engine (internal combustion engine)
2 Engine body 3 Intake device 4 Exhaust device 5 Exhaust purification device 6 Turbocharger 8 Fuel supply device 9 ECU
41 Exhaust pipe 50 Exhaust aftertreatment device (catalyst)
51 Reducing Agent Injection Valve 52 Attachment (Support Member)
100a Nozzle part 101 Nozzle body 103 Nozzle 103a Tip surface 111 Nozzle housing part 112 Shroud part 112a Through hole C1 Nozzle shaft center C2 Shaft part shaft center G Exhaust gas S Gap

Claims (4)

A catalyst provided in an exhaust pipe of an internal combustion engine for purifying exhaust gas, a reducing agent injection valve having a nozzle for injecting a reducing agent into the exhaust pipe upstream of the catalyst, and the reducing agent injection valve in the exhaust pipe An exhaust purification device that recovers the function of the catalyst by adding the reducing agent to the exhaust gas from the reducing agent injection valve.
The support member communicates from the nozzle housing portion to the exhaust pipe, the nozzle housing portion containing at least a part of the nozzle, and is positioned in the forward direction from the tip surface of the nozzle. A shroud portion having a through hole with an inner diameter smaller than the inner diameter,
During gap is provided between the nozzle and the shroud portion,
Exhaust purification apparatus axis of the nozzle, characterized that you have eccentrically in the upstream direction of the flow of the exhaust gas with respect to the axis of the nozzle housing portion. The inner diameter of the through hole of the shroud portion, an exhaust purifying apparatus according to claim 1, wherein the smaller than the outer diameter of the nozzle. The exhaust purification device according to claim 1, wherein the shroud portion covers a part of a tip surface of the nozzle. The exhaust emission control device according to any one of claims 1 to 3 , wherein an injection direction of the nozzle is downstream in a flow direction of the exhaust gas.

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