JPWO2013038790A1 - Exhaust gas purification device for internal combustion engine - Google Patents

Abstract

An exhaust emission control device for an internal combustion engine capable of preventing a problem in injection of a reducing agent due to high heat during execution of regeneration control of a particulate filter is provided. A shut-off unit that can be switched to a state in which the reducing agent injection valve is opened or shut off with respect to the flow of exhaust gas that has passed through the particulate filter, and the reduction during the period when the regeneration control of the particulate filter is not executed An electronic control unit that holds the blocking unit in the opened state of the agent injection valve and switches the blocking unit to the closed state of the reducing agent injection valve during the regeneration period of the particulate filter. .

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine provided in an exhaust passage of the internal combustion engine, and more particularly to an exhaust gas purification apparatus for an internal combustion engine having a configuration in which a reducing agent injection valve is provided downstream of a particulate filter in an exhaust flow. .

Conventionally, as an exhaust gas purification device that purifies exhaust gas discharged from an internal combustion engine mounted on a vehicle or the like, a particulate filter for collecting particulate matter in exhaust gas, and for removing NO _x in the exhaust gas and NO _X reduction catalyst, the exhaust gas purification device that includes a reducing agent injection valve for supplying the liquid reducing agents are known in the exhaust is fixed to the exhaust pipe. In such an exhaust purification device, a particulate filter is generally provided on the most upstream side of the exhaust flow so that particulate matter in the exhaust does not adhere to the NO _x reduction catalyst or the like.

  Since the particulate filter may be clogged by the collected particulate matter, regeneration control for oxidizing (burning) the particulate matter collected by the particulate filter is executed at a predetermined timing. It has become so. The regeneration control of the particulate filter is performed by a method of flowing high-temperature exhaust gas into the particulate filter or a method of directly heating the particulate filter (see Patent Document 1).

JP 2010-43583 A (paragraph [0062], FIG. 1 etc.)

However, during regeneration control of the particulate filter, high-temperature exhaust gas flows out downstream of the particulate filter, so that it is downstream of the particulate filter and upstream of the NO _X reduction catalyst. There is a possibility that the reducing agent injection valve fixed to the exhaust pipe is exposed to high heat. If the reducing agent injection valve is exposed to high heat, the reducing agent injection valve may be damaged by heat. In particular, when an aqueous urea solution is used as the liquid reducing agent, the aqueous urea solution may crystallize at the tip of the reducing agent injection valve, and the reducing agent may not be supplied with high accuracy.

  In view of such a problem, the inventor of the present invention provides a shut-off portion for switching the exhaust gas flow of the internal combustion engine to a state in which the reducing agent injection valve is opened or shut off with respect to the flow of exhaust. It has been found that such a problem can be solved by providing an electronic control unit that switches the blocking portion so that the reducing agent injection valve is blocked from the exhaust flow during regeneration of the particulate filter. It is a thing. That is, an object of the present invention is to provide an exhaust emission control device for an internal combustion engine that can prevent a problem in injection of a reducing agent due to high heat during execution of regeneration control of a particulate filter.

According to the present invention, the particulate filter that collects particulate matter in the exhaust discharged from the internal combustion engine, the NO _x reduction catalyst provided on the downstream side of the particulate filter, and the particulate in the exhaust flow In an exhaust gas purification apparatus for an internal combustion engine, comprising: a reducing agent injection valve that is fixed to an exhaust pipe downstream of the filter and upstream of the NO _x reduction catalyst and injects a reducing agent into the exhaust pipe. A shut-off portion that can be switched to a state in which the reducing agent injection valve is opened or shut off with respect to the flow of exhaust gas that has passed through the particulate filter, and during a period in which regeneration control of the particulate filter is not executed While holding the shut-off part in the opened state of the reducing agent injection valve, during the regeneration period of the particulate filter And an electronic control unit that switches the shut-off portion to the shut-off state of the reducing agent injection valve. An exhaust purification device for an internal combustion engine is provided, which can solve the above-described problems.

  That is, the exhaust gas purification apparatus for an internal combustion engine according to the present invention enables the injection of the reducing agent into the exhaust pipe by the reducing agent injection valve except during the regeneration of the particulate filter, while the regeneration of the particulate filter. The reducing agent injection valve can be cut off from the flow of exhaust gas. Therefore, when the particulate filter is regenerated, the opportunity for the reducing agent injection valve to be exposed to high heat is reduced, and it is possible to prevent a malfunction from occurring in the injection of the reducing agent.

  Further, in configuring the exhaust gas purification apparatus for an internal combustion engine of the present invention, the reducing agent injection valve is fixed to an introduction pipe that is branched and connected from a main exhaust pipe, and the blocking portion is the main exhaust pipe. It is preferable that the opening of the introduction pipe facing the opening is configured to be openable or shut off. With this configuration, it is possible to prevent the reducing agent injection valve from being exposed to high heat even during normal operation of the internal combustion engine by keeping the reducing agent injection valve away from the main flow of exhaust gas.

  Further, in configuring the exhaust gas purification apparatus for an internal combustion engine according to the present invention, the blocking portion includes a shielding member for blocking the flow of the exhaust gas toward the reducing agent injection valve inside the exhaust pipe, and an outside of the exhaust pipe. And an actuator that moves the position of the shielding member. With this configuration, when the particulate filter is regenerated or not regenerated, the state of the blocking unit can be switched by the electronic control unit, and the actuator can be protected from high heat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for illustrating the overall configuration of an exhaust emission control device for an internal combustion engine according to an embodiment of the present invention. It is a figure shown in order to demonstrate the structural example of a interruption | blocking part. It is sectional drawing of the exhaust pipe shown in order to demonstrate the structural example of a interruption | blocking part. It is a figure which shows operation | movement of a interruption | blocking part. It is a figure shown in order to demonstrate another structural example of a interruption | blocking part. It is a figure which shows operation | movement of another structural example of a interruption | blocking part.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment relating to an exhaust gas purification apparatus for an internal combustion engine according to the present invention will be specifically described with reference to the drawings.
In addition, what is attached | subjected with the same code | symbol in each figure has shown the same component unless there is particular description, and description is abbreviate | omitted suitably.

  An exhaust gas purification apparatus 10 for an internal combustion engine shown in FIG. 1 is configured as an apparatus for purifying exhaust gas exhausted from the internal combustion engine, interposed in an exhaust pipe 11 connected to an internal combustion engine (not shown). A typical example of the internal combustion engine is a diesel engine, but is not limited thereto.

The exhaust purification device 10 includes a particulate filter 15, a NO _x purification catalyst 17, a reducing agent supply device 20, a blocking unit 30, and an electronic control unit 35. Particulate filter 15 and NO _X purification catalyst 17, there is provided in the exhaust pipe 11, from the upstream side in the exhaust stream, they are arranged in order of the particulate filter 15, NO _X purification catalyst 17.

  The particulate filter 15 has a function of collecting particulate matter such as soot (hereinafter referred to as “PM (Particulate Material)”) contained in the exhaust discharged from the internal combustion engine. The particulate filter 15 is typically a known diesel particulate filter having a honeycomb structure, but is not limited thereto.

  The particulate filter 15 is regenerated by regeneration control that oxidizes (combusts) the collected PM at a predetermined time. In the regeneration control, the particulate filter 15 is heated by heating means such as a burner or a heater, or an oxidation catalyst is provided upstream of the particulate filter 15 and the internal combustion engine is operated under a predetermined condition so that the oxidation catalyst is not used. This is performed by heating the particulate filter 15 by using oxidation heat generated by supplying the fuel. At the time of regenerative control, the exhaust temperature downstream of the particulate filter 15 is, for example, about 400 to 800 ° C.

  In this regeneration control, during operation of the internal combustion engine, the differential pressure before and after the particulate filter 15 detected using the differential pressure sensor, the amount of collected PM estimated by the calculation, etc. exceeded a predetermined threshold value. When executed. Furthermore, regeneration control is executed even when the internal combustion engine is stopped.

The NO _x purification catalyst 17 has a function of decomposing nitrogen oxides contained in the exhaust gas. As the NO _x purification catalyst 17, a NO _x selective reduction catalyst or a NO _x storage catalyst is mainly used. The NO _X selective reduction catalyst is a catalyst that adsorbs the reducing agent generated from the liquid reducing agent supplied by the reducing agent supply device 20 and selectively reduces nitrogen oxide in the inflowing exhaust gas. In this case, an aqueous urea solution, unburned fuel, or the like can be used as the liquid reducing agent. _The NO _X storage catalyst, while absorbing the NO _X in the exhaust gas at low concentration of oxygen in the exhaust, when the oxygen concentration in the exhaust gas becomes higher, the NO _X with the unburned fuel (HC) to release the NO _X It is a catalyst to reduce. In this case, unburned fuel can be used as the liquid reducing agent.

The reducing agent supply device 20 is a device for supplying a liquid reducing agent for purifying NO _x into the exhaust gas upstream of the NO _x purification catalyst 17 and downstream of the particulate filter 15. . The reducing agent supply device 20 is mainly configured by a reducing agent tank 21, a pump 23, and a reducing agent injection valve 27. The pump 23 and the reducing agent injection valve 27 are driven and controlled by the electronic control unit 35. In particular, the reducing agent injection valve 27 is configured to lift and open the valve body when the electromagnetic solenoid coil is energized. It has become a thing. The reducing agent injection valve 27 has a relatively heat-sensitive characteristic due to the influence of the heat resistance temperature of the electromagnetic solenoid or the heat resistance temperature of the resin portion constituting the reducing agent injection valve 27.

The reducing agent supply device 20 supplies the liquid reducing agent having a predetermined pressure to the reducing agent injection valve 27 by the pump 23 while reducing the amount of the liquid reducing agent calculated based on the NO _x concentration in the exhaust gas. Injected by valve 27. In the exhaust purification apparatus 10 according to the present embodiment, a reducing agent injection valve 27 is fixed to an introduction pipe 13 that is branched from the exhaust pipe 11, and the front end portion of the reducing agent injection valve 27 is directly exhausted. It is not exposed to the flow. Therefore, during the period in which the internal combustion engine is in a normal operating state, the reducing agent injection valve 27 is not easily exposed to high heat. In particular, when a urea aqueous solution is used as the liquid reducing agent, crystallization due to evaporation of water in the urea aqueous solution is less likely to occur in the nozzle hole portion of the reducing agent injection valve 27.

  Further, in the exhaust gas purification apparatus 10 for the internal combustion engine according to the present embodiment, the exhaust pipe 11 is provided with a blocking portion 30 for closing the opening portion of the introduction pipe 13 facing the exhaust pipe 11. The blocking part 30 is arranged so as to be movable back and forth in the length direction of the exhaust pipe 11 and can block the opening part of the introduction pipe 13, an actuator 33 for moving the blocking member 31 forward and backward, and a blocking member The guide cover 32 has a guide function of 31 forward / backward movement and a function of suppressing leakage of exhaust gas.

  2 and 3 show a configuration of the blocking unit 30 according to the present embodiment. FIG. 2 is a perspective view of the exhaust pipe 11 provided with the blocking portion 30, and FIG. 3 is a cross-sectional view of the XX section of FIG. In FIG. 2, the guide cover 32 configuring the blocking unit 30 is omitted.

  In this example, the blocking member 31 is configured by a plate-like member having a shape corresponding to the inner peripheral surface of the exhaust pipe 11. A rod 33 a is connected to the blocking member 31, and the rod 33 a is led out of the exhaust pipe 11 through a slit portion 11 a formed in the exhaust pipe 11 and provided outside the exhaust pipe 11. Connected to the actuator 33 (see FIG. 1).

  A guide cover 32 is provided on the inner peripheral surface of the exhaust pipe 11 to guide the forward / backward movement of the blocking member 31 and to suppress exhaust leakage. In addition, a seal member 37 is provided in the slit portion 11a of the exhaust pipe 11 so as not to hinder the movement of the rod 33a in the slit portion 11a and to prevent the exhaust gas from leaking from the exhaust pipe 11 to the outside. .

  The actuator 33 is not particularly limited as long as it can move the rod 33a forward and backward under the control of the electronic control unit 35. For example, the actuator 33 can be configured using an electromagnetic motor, an air cylinder, or the like.

  The electronic control unit 35 is configured around a known microcomputer, and executes regeneration control of the particulate filter 15 and drive control of the pump 23, the reducing agent injection valve 27, and the actuator 33. Run. Further, in the exhaust gas purification apparatus 10 for the internal combustion engine according to the present embodiment, the electronic control unit 35 executes drive control of the blocking unit 30.

  As shown in FIG. 4A, the electronic control unit 35 opens the introduction pipe 13 during the period when the regeneration control of the particulate filter 15 is not executed, that is, during the period when the internal combustion engine is in a normal operation state. The blocking member 31 is held at a position where the part is opened, and the liquid reducing agent injection control is executed.

  On the other hand, the electronic control unit 35 needs to control regeneration of the particulate filter 15, and when entering the execution preparation stage, as shown in FIG. The member 31 is moved. At the same time, the electronic control unit 35 prohibits the injection control of the liquid reducing agent. That is, when the differential pressure before and after the particulate filter 15 exceeds a predetermined threshold, when the estimated amount of collected PM exceeds a predetermined threshold, or when the ignition switch of the internal combustion engine is turned off For example, the electronic control unit 35 starts the regeneration control of the particulate filter 15 after blocking the opening of the introduction pipe 13 facing the exhaust pipe 11 by the blocking member 31 while stopping the injection of the liquid reducing agent. .

  Thereafter, when the regeneration control of the particulate filter 15 is completed, the electronic control unit 35 returns the blocking member 31 to the original position and cancels the prohibition of the liquid reducing agent injection control.

  According to the exhaust gas purification apparatus 10 for an internal combustion engine according to the present embodiment described above, the liquid reducing agent is injected into the exhaust pipe 11 by the reducing agent injection valve 27 except during the regeneration control of the particulate filter 15. On the other hand, during the regeneration control of the particulate filter 15, the reducing agent injection valve 27 can be blocked from the flow of exhaust. Therefore, the opportunity for the reducing agent injection valve 27 to be exposed to high heat during the regeneration control of the particulate filter 15 is reduced, and the possibility that the reducing agent injection valve 27 is damaged by high heat can be reduced. At the same time, when the urea aqueous solution is used as the liquid reducing agent, the possibility that the urea aqueous solution crystallizes at the tip portion of the reducing agent injection valve 27 can be reduced. As a result, it is possible to prevent a malfunction from occurring in the injection of the liquid reducing agent.

  Moreover, since the exhaust gas purification apparatus 10 for an internal combustion engine according to the present embodiment fixes the reducing agent injection valve 27 to the introduction pipe 13 that is branched from the main exhaust pipe 11 and connected thereto, It is possible to prevent the reducing agent injection valve 27 from being exposed to high heat even when the reducing agent injection valve 27 is moved away and during normal operation of the internal combustion engine.

  In the exhaust gas purification apparatus 10 for an internal combustion engine according to the present embodiment, the shutoff member 30 is configured by the shutoff member 31 disposed inside the exhaust pipe 11 and the actuator 33 provided outside the exhaust pipe 11. Therefore, when the particulate filter 15 is regenerated or not regenerated, the state of the blocking unit 30 can be switched by the electronic control unit 35, and the actuator 33 can be protected from high heat.

  However, the exhaust gas purification apparatus 10 for an internal combustion engine according to the present embodiment described above shows one aspect of the present invention and does not limit the present invention, and each embodiment is within the scope of the present invention. It is possible to change arbitrarily within. For example, the exhaust gas purification apparatus 10 for an internal combustion engine according to the present embodiment can be modified as follows.

  The configuration and form of each component constituting the exhaust gas purification apparatus 10 for an internal combustion engine described in the present embodiment is merely an example, and can be arbitrarily changed.

  Also about the structure of the interruption | blocking part 30, it can deform | transform into various aspects. FIG.5 and FIG.6 (a)-(b) has shown another structural example of the interruption | blocking part. The blocking portion 40 has a shape corresponding to the inner peripheral surface of the exhaust pipe 11, and controls a blocking member 41 that moves forward and backward in the circumferential direction along the inner peripheral surface of the exhaust pipe 11, and the forward and backward movement of the blocking member 41. And a guide cover 42 having a function of guiding the forward and backward movement of the blocking member 41 and a function of suppressing exhaust leakage.

  In a period in which the regeneration control of the particulate filter 15 is not executed, that is, in a period in which the internal combustion engine is in a normal operation state, as shown in FIG. 6A, the opening portion of the introduction pipe 13 is opened. The blocking member 41 is held and the liquid reducing agent injection control is executed. On the other hand, when the regeneration control of the particulate filter 15 is required and the execution preparation stage is entered, as shown in FIG. 6B, the blocking member 41 is moved to a position where the opening portion of the introduction pipe 13 is blocked. . Such a blocking unit 40 can also achieve the same effect as that of the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment.

  In the exhaust gas purification apparatus 10 for an internal combustion engine described in the present embodiment, it is described that all control is executed by one electronic control unit 35. However, the electronic control unit 35 is divided into an appropriate number. It does not matter.

In the exhaust gas purification apparatus 10 for an internal combustion engine described in the present embodiment, the reducing agent injection valve 27 is fixed to the introduction pipe 13 branched and connected from the exhaust pipe 11. Can be directly fixed to the exhaust pipe 11, and a blocking portion can be provided on the upstream side or the like so that the flow of the exhaust toward the reducing agent injection valve 27 can be blocked.

Claims (3)

A particulate filter that collects particulate matter in the exhaust discharged from the internal combustion engine, a NO _x reduction catalyst provided on the downstream side of the particulate filter, and a downstream side of the particulate filter in the flow of exhaust, And an exhaust gas purification apparatus for an internal combustion engine, comprising: a reducing agent injection valve fixed to an exhaust pipe upstream of the NO _X reduction catalyst and injecting a reducing agent into the exhaust pipe,
A blocking unit that can be switched to a state in which the reducing agent injection valve is opened or blocked with respect to an exhaust flow that has passed through the particulate filter;
During the period when regeneration control of the particulate filter is not being executed, the reducing agent injection valve is held in the opened state while the blocking portion is held, while during the regeneration period of the particulate filter, the reducing agent injection valve An electronic control unit that switches the blocking portion to the blocking state;
An exhaust emission control device for an internal combustion engine, comprising: The reducing agent injection valve is fixed to an introduction pipe that is branched and connected from a main exhaust pipe,
2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the blocking portion is configured to be able to open or block an opening of the introduction pipe facing the main exhaust pipe.   The blocking portion includes: a shielding member that blocks the flow of the exhaust toward the reducing agent injection valve inside the exhaust pipe; and an actuator that is provided outside the exhaust pipe and moves the position of the shielding member. The exhaust emission control device for an internal combustion engine according to claim 1, wherein the exhaust gas purification device is an internal combustion engine.

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