JP3600509B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purification device for an internal combustion engine that purifies exhaust gas discharged from the internal combustion engine.
[0002]
[Prior art]
A selective reduction type NOx catalyst that reduces or decomposes harmful NOx in exhaust gas with a reducing agent in an oxygen-rich atmosphere is discharged from an internal combustion engine (for example, a diesel engine or a lean burn gasoline engine) capable of burning at a lean air-fuel ratio. Is widely used as an exhaust gas purifying apparatus for purifying NOx in exhaust gas.
[0003]
In such a selective reduction type NOx catalyst, a hydrocarbon is often used as a reducing agent, but the use of a reducing agent derived from ammonia such as urea as another reducing agent is being studied. For example, as a device using solid urea as a reducing agent, there is a reducing agent supply device described in JP-A-2000-27626.
[0004]
The reducing agent supply device described in Japanese Patent Application Laid-Open No. 2000-27626 discloses a storage tank for solid urea, a spring member fixed to the inner upper surface of the storage tank, and a crushing mechanism fixed to a lower end of the spring member. And a crushing means comprising: The grinding mechanism has a plurality of grinding arms extending radially from the vertical bar to near a sidewall of the storage device, the lower tip of the vertical bar extending inward from the bottom wall of the storage device. It is slidably guided in the vertical direction by the guide member.
[0005]
When the solid urea as the reducing agent is supplied to the storage device, the spring member of the crushing means is made freely expandable and contractable and is not buried in the solid urea. Solid urea is likely to be agglomerated in the storage device, but since the above-mentioned pulverizing means is disposed in the storage device, the pulverizing mechanism guided slidably in the up and down direction by the guide member has a spring due to vehicle vibration. In order to vibrate up and down through the element, the urea mass can be comminuted throughout the storage device. Therefore, the crushed urea in the storage device can be continuously discharged.
[0006]
[Problems to be solved by the invention]
However, in the reducing agent supply device described in JP-A-2000-27626, a spring member and a crushing mechanism are required to discharge the solid reducing agent from the storage tank, and the structure in the storage tank is complicated. There is.
[0007]
Further, this apparatus does not disclose how to supply the solid reducing agent discharged from the storage tank to the exhaust gas passage, with respect to specific supply means. In practice, the problem is how to reliably supply a predetermined amount of reducing agent to a predetermined position upstream of the selective reduction NOx catalyst installed in the exhaust passage, and supply of a simple and excellent controllable reducing agent. It is desired to provide a device.
[0008]
The present invention has been made in view of such circumstances, and it is more reliable to store and supply a reducing agent, and to efficiently reduce a predetermined amount of a reducing agent to an exhaust gas upstream of a selective reduction type NOx catalyst. It is an object to provide a reducing agent supply device that can supply a reducing agent to a passage.
[0009]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. That is, the present invention provides a selective reduction type NOx catalyst provided in an exhaust gas passage of an internal combustion engine for reducing or decomposing NOx in the presence of a reducing agent derived from ammonia, and a solid reducing agent storage for storing a solid reducing agent. A molten reducing agent storage unit that heats and liquefies and stores the solid reducing agent introduced from the solid reducing agent storage unit; and stores the solid reducing agent stored in the solid reducing agent storage unit in the molten reducing agent storage unit. a solid reductant conveying means for conveying the parts, and a smelting reduction agent supply means for supplying to the exhaust gas passage upstream of the said molten reducing agent the selective reduction type NOx catalyst liquefied liquefied reducing agent reservoir The exhaust gas purifying apparatus for an internal combustion engine, wherein a surface of the reducing agent is coated with a sticking inhibitor that prevents the reducing agents from sticking to each other.
[0010]
The solid reducing agent stored in the solid reducing agent storage unit is guided to the molten reducing agent storage unit by the solid reducing agent transport unit and liquefied by heating, and the liquefied reducing agent is selectively reduced NOx by the molten reducing agent supply unit. It is supplied to an exhaust passage upstream of the catalyst.
[0011]
The internal combustion engine in the present invention can be exemplified by a direct-injection-type lean-burn gasoline engine or a diesel engine.
Examples of the selective reduction type NOx catalyst include a catalyst in which a transition metal such as Cu is supported on zeolite by ion exchange, a titania / vanadium catalyst, and a catalyst in which a noble metal is supported on zeolite or alumina.
[0012]
In the present invention, the form of the reducing agent may be spherical, and a large number of the reducing agents are stored in the solid reducing agent storage section. In this case, if the solid reducing agent conveying means is an inclined surface formed in the solid reducing agent storage section, the solid reducing agent rolls on the inclined surface and is continuously discharged.
[0013]
As the reducing agent, for example, urea or ammonium carbamate can be used. The shape of the solid reducing agent in the storage chamber may be spherical or rod- like. By coating the surface of the solid reducing agent with the anti-sticking agent, the reducing agents are prevented from sticking to each other, and the transport of the reducing agent can be performed smoothly.
[0014]
The solid reducing agent transporting means may include a motor and a rotating body driven by the motor, and the rotating body may be configured to contact the reducing agent and carry it out of the solid reducing agent storage unit.
[0015]
In the present invention, the heat source for heating and liquefying the solid reducing agent in the molten reducing agent storage unit can be an electric heater.
It is preferable to provide a temperature control means for controlling the temperature of the reducing agent within a predetermined temperature range so that the solid reducing agent does not gasify in the molten reducing agent storage unit. When the solid reducing agent is heated to an unnecessarily high temperature, the reducing agent is altered and solidified to cause deterioration in fluidity and change in characteristics. Further, the reducing agent may be gasified, and the gasified reducing agent may leak out of the storage means. This can be prevented by providing the temperature control means.
[0016]
The operation of the liquefied reducing agent is controlled by, for example, an engine control electronic control unit (ECU), and the liquefied reducing agent can be supplied by supply amount control means such as an injector that injects a predetermined amount into the exhaust gas passage.
[0017]
In the present invention, since the reducing agent is stored in a solid state and is supplied after being heated and liquefied, the apparatus can be reduced in size and simplified, and the supply amount of the reducing agent can be controlled with high precision. It is.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described with reference to the drawings of FIGS. In each of the embodiments described below, the present invention is applied to a vehicle driving diesel engine as an internal combustion engine.
[First Embodiment]
A first embodiment of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described with reference to FIGS. A piston 6 is provided in the combustion chamber 2 of each cylinder of the diesel engine 1 for a vehicle, and air is introduced from an intake pipe 4 through an air cleaner 3. Fuel is injected into each combustion chamber 2 from a fuel injection valve 5, which burns at a lean air-fuel ratio.
[0019]
The exhaust gas discharged from each combustion chamber 2 is exhausted to the atmosphere through an exhaust pipe 7, a NOx catalytic converter 8, and an exhaust pipe 9. The NOx catalytic converter 8 contains a zeolite-silica-based or titania-vanadium-based selective reduction type NOx catalyst 10 that reduces or decomposes NOx in exhaust gas in the presence of a reducing agent.
[0020]
In order to purify NOx in exhaust gas with the selective reduction type NOx catalyst 10, the presence of a reducing agent used for the purification is required. Therefore, this exhaust gas purification device is provided with a reducing agent adding device (reducing agent adding means) 11 for adding a reducing agent into the exhaust pipe 7 upstream of the NOx catalytic converter 8.
[0021]
This reducing agent addition device 11 liquefies solid urea A as a solid reducing agent and supplies it to the exhaust pipe 7. The apparatus includes a storage container 12 that is a solid reducing agent storage unit that stores solid urea A, a liquid urea storage chamber 13 that is a molten reducing agent storage unit connected to a lower portion of the storage container 12, And an addition control valve 14 provided at a lower portion of the storage chamber 13.
[0022]
The storage container 12 has a reducing agent inlet 12a at the top, and the inlet 12a can be opened and closed by a lid 12b, and the bottom surface 12c is an inclined surface as shown in FIGS. I have. A discharge port 12d is formed at the lowest portion of the bottom surface 12c, and communicates with the liquid urea storage chamber 13 through a communication passage 12e.
[0023]
In FIG. 2, the solid reducing agent stored in the storage container 12 is solid urea A, and the solid urea A is formed into a spherical shape. The solid urea A rolls on the bottom surface 12c, and flows from the discharge port 12d to the liquid urea storage chamber. Fall toward 13.
[0024]
Further, as shown in FIG. 3, the solid urea A may be formed into a rod shape and guided to the outlet 12d by the inclined bottom surface 12c. The solid urea A slides down on the bottom surface 12c and is discharged from the discharge port 12d toward the liquid urea storage chamber 13.
[0025]
Since the solid urea A has a property of absorbing moisture and being easily fixed, the solid reducing agent storage unit 12 is provided with a dehumidifying means 15 made of silica gel or the like. The dehumidifying means 15 is a container containing silica gel or the like, and communicates with a container 12 to which solid urea A is supplied via a passage 15a.
[0026]
In addition, since the solid urea A is coated with the anti-sticking agent, it sticks to each other to form a lump, thereby preventing a situation in which discharge becomes difficult.
Next, the liquid urea storage chamber 13 is provided with a heating source such as an electric heater (not shown), and heats the solid urea A supplied from the upper storage container 12 via the communication path 12c to liquefy the liquid. Urea. The liquid urea is added into the exhaust pipe 7 by controlling the flow rate by the addition control valve 14 shown in FIG. The tip of the addition control valve 14 is a needle valve 14a, and a communication path 12c from the liquid urea storage chamber 13 is connected to a supply path 14d through which an axial valve body 14c penetrates in the axial direction, and the valve body 14c reciprocates. It is movably guided by a support 14e. At the rear end of the addition control valve 14, a stopper 14f attached to the rear of the penetrating valve body 14c is provided, which is locked to the rear end face of the main body of the addition control valve 14. A solenoid is arranged behind the stopper 14f, and when excited, attracts the stopper 14f backward. A seal 14b is provided on the outer peripheral surface of the support 14e of the valve element 14c so that the supplied liquid urea does not leak.
[0027]
The opening and closing time of the addition control valve 14 is duty ratio controlled by the ECU 16 to control the flow rate and addition timing of the liquid urea. Therefore, the solenoid 37 is energized by energization according to a command from the ECU 16, and the stopper 14f is moved backward. When the valve body 14c moves rearward with this, and the needle valve 14a at the tip opens, a predetermined amount of urea is added into the exhaust passage for a predetermined time during the valve opening.
[0028]
When the energization of the solenoid 37 is stopped, the stopper 14f is returned to the original position by the spring 38, the needle valve 14a is closed, and the addition of urea ends. A pump (not shown) that pressurizes liquid urea and sends it to the pressure adjusting unit is provided between the addition control valve 14 and the liquid urea storage chamber 13, and the liquid urea is pressurized to a constant pressure in the pressure adjusting unit. The pressure regulator 39 is provided for pressure.
[0029]
The heating source such as an electric heater provided in the liquid urea storage chamber 13 is controlled by the ECU 16 so that the temperature of the solid urea A in the liquid urea storage chamber 13 becomes an optimum temperature (about 160 to 230 ° C.) for liquefaction. Its operation is controlled. This is because if the solid urea A is heated to a temperature higher than the optimum temperature, the solid urea A may be gasified.
[0030]
Further, the storage container 12 is provided with a remaining amount sensor 17 for detecting the remaining amount of the solid urea A, and the remaining amount sensor 17 outputs an output signal proportional to the detected remaining amount of the solid urea A to the ECU 16. When an input signal indicating a predetermined remaining amount (hereinafter, referred to as an alarm remaining amount) is input from the remaining amount sensor 17, the ECU 16 turns on the alarm lamp 23 of the meter panel 22, and outputs the solid urea A. Notify when the battery level is low. The ECU 16 stops the operation of the reducing agent addition device 11 and fully closes the addition control valve 14 when an input signal indicating a lower limit value smaller than the alarm remaining amount value is input from the remaining amount sensor 17. Stop adding liquid urea.
[0031]
The liquid urea storage chamber 13 is provided with a temperature sensor 18 for detecting the liquid temperature of the liquid urea, and the temperature sensor 18 outputs an output signal proportional to the detected liquid urea liquid temperature to the ECU 16.
[0032]
On the other hand, the exhaust pipe 7 upstream of the NOx catalytic converter 8 is provided with a catalyst-input gas temperature sensor 19 for detecting the temperature of the exhaust gas flowing into the NOx catalytic converter 8, and is proportional to the detected catalyst-input gas temperature. An output signal is output to the ECU 16.
[0033]
A NOx sensor 21 is provided in the exhaust pipe 7 upstream of the catalyst input gas temperature sensor 19 to measure the amount of NOx in the exhaust gas.
An ammonia gas sensor 36 is provided in the exhaust pipe 7 downstream of the catalyst inlet gas temperature sensor 19, and outputs an output signal proportional to the measured amount of ammonia gas to the ECU 16.
[0034]
The ECU 16 is composed of a digital computer and includes a ROM (Read Only Memory), a RAM (Random Access Memory), a CPU (Central Processor Unit), an input / output port, and an output port interconnected by a bidirectional bus. In addition to performing the basic control such as the fuel injection amount control in this embodiment, in this embodiment, the addition amount control of the liquid urea is performed.
[0035]
For these controls, an input signal from the air flow meter 20 is input to an input port of the ECU 16 via an A / D converter. The air flow meter 20 outputs an output signal proportional to the amount of intake air to the ECU 16, and the ECU 16 calculates the amount of intake air based on the output signal of the air flow meter 20.
[0036]
Since the NOx sensor 21 is installed in the exhaust pipe 7 upstream of the NOx catalytic converter 8, the NOx sensor 21 can detect the amount of NOx flowing into the NOx catalytic converter 8, and outputs an output signal proportional to the detected NOx concentration to the ECU 16. Output to The ECU 16 calculates the NOx emission amount from the NOx concentration detected by the NOx sensor and the intake air amount detected by the air flow meter 20.
[0037]
The ECU 16 calculates a target addition amount of the liquid urea required for purifying NOx based on the NOx emission amount, and calculates a duty ratio of the addition control valve 14 that can obtain a flow rate corresponding to the target addition amount. The duty ratio of the addition control valve 14 is controlled.
[0038]
The flow rate of the liquid urea flowing through the addition control valve 14 changes when the liquid temperature of the liquid urea and the back pressure at the outlet side of the addition control valve 14 are different even when the duty ratio of the addition control valve 16 is the same. When the duty ratio of the addition control valve 14 is controlled, the ECU 16 corrects the target duty ratio based on the liquid temperature of the liquid urea detected by the temperature sensor 18 and the gas pressure detected by the incoming gas pressure sensor 19.
[0039]
Next, the operation of the exhaust gas purifying apparatus for an internal combustion engine will be described. As described above, the ECU 16 controls the duty ratio of the addition control valve 14 according to the operating state of the engine 1, that is, according to the NOx emission amount, and adds an appropriate amount of liquid urea into the exhaust pipe 7. The liquid urea added into the exhaust pipe 7 is heated by the exhaust gas, and as a result, is immediately vaporized and becomes a reducing gas (ammonia gas), and flows into the NOx catalytic converter 8 together with the exhaust gas.
[0040]
The reducing gas reduces or decomposes NOx contained in the exhaust gas on the selective reduction type NOx catalyst 10. The purified exhaust gas is discharged into the atmosphere through the exhaust pipe 9.
[0041]
It should be noted that the selective reduction type NOx catalyst 10 has a property that the NOx purification rate is low when the exhaust gas temperature is lower than a predetermined temperature, and the NOx purification rate sharply increases when the exhaust gas temperature exceeds the predetermined temperature. Therefore, even if the reducing gas is added when the exhaust gas temperature is low, the added reducing gas passes through the NOx converter 8 without being used for the NOx reduction reaction and is released to the atmosphere. Therefore, in this embodiment, when the incoming gas temperature detected by the incoming gas temperature sensor 19 is equal to or lower than the predetermined temperature, the ECU 16 controls the addition control valve 14 to fully close, thereby stopping the addition of the liquid urea. In this way, leakage of reducing gas is prevented beforehand.
[0042]
In the above-described embodiment, a NOx sensor for detecting the NOx concentration of the exhaust gas is provided in the exhaust pipe 7 on the upstream side of the NOx catalytic converter 8, and the NOx concentration detected by the NOx sensor and the NOx concentration detected by the air flow meter 20 are used. Although the NOx emission amount is calculated from the intake air amount, the following method may be adopted instead.
That is, the relationship between the engine load and the amount of NOx exhausted from the engine 1 based on the engine speed is obtained and mapped in advance, and the NOx emission map is stored in the ECU 16. The ECU 16 estimates and calculates the amount of NOx discharged from the engine 1 based on the engine load and the engine speed with reference to the NOx discharge map. In this case, an input signal from an accelerator opening sensor (not shown) and an input signal from a crank angle sensor are input to the input port of the ECU 16. The accelerator opening sensor outputs an output voltage proportional to the accelerator opening to the ECU 16, and the ECU 16 calculates an engine load based on an output signal from the accelerator opening sensor. The crank angle sensor outputs a main force pulse to the ECU 16 every time the crankshaft of the engine 1 rotates by a predetermined angle, and the ECU 16 calculates the engine rotation speed based on the output pulse.
[0043]
In the exhaust gas purifying apparatus of this embodiment, solid urea is heated and liquefied into liquid urea, and the liquid urea is added into the exhaust pipe 7 by controlling the flow rate with the addition control valve 14. Since the amount of heat required to liquefy the solid urea is smaller than the amount of heat required to vaporize the solid urea, there is an advantage that the heating source (electric heater) can be smaller than before.
[0044]
Further, liquid urea is produced by directly heating and liquefying solid urea, so that the concentration becomes 100% and a high concentration addition amount control is required. However, since the control target is not a gas but a liquid, the addition control valve 14 Thus, high-precision flow control can be sufficiently performed.
[Second embodiment]
A second embodiment of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described with reference to FIG.
[0045]
In the second embodiment, a forced transport mechanism for solid urea A is provided on the bottom surface of the solid reducing agent storage unit 12.
The solid reducing agent storage unit 12 is the same as that of the first embodiment. That is, as shown in FIG. 4, the lower part of the solid reducing agent storage part 12 has an inclined surface 12c, and the lowest part of the inclined surface 12c has an outlet 12d. Is in communication with
[0046]
Here, the solid urea A stored in the storage container 12 is rod-shaped, and a plurality of rod-shaped fixed ureas A are discharged one by one from the discharge port 12d. At the periphery of the discharge port 12d, two gear-shaped rotating bodies 26 that are connected to the motor 25 and rotate are provided so as to face each other. These rotating bodies 26 face the carry-out path of the solid urea A, and a part of the outer periphery thereof projects into the carry-out path. Therefore, the rotating body 26 can come into contact with the solid urea A, and the solid urea A sliding on the slope can be forcibly moved downward.
[0047]
The solid urea A is sent to the liquid urea storage chamber 13 via the communication passage 12e below the outlet 12d. As in the first embodiment, the solid urea A that has reached the liquid urea storage chamber 13 is liquefied and supplied to the exhaust passage 7 in a fixed amount.
[0048]
The operation and stop of the motor 25 are controlled by the ECU 16. The operation timing and period of the motor 25 can be appropriately set in consideration of the environment in the place where the engine 1 is used, seasonal factors, and the like.
[0049]
According to this embodiment, solid urea A can be continuously and reliably taken out of storage container 12.
[Third Embodiment]
A third embodiment of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described with reference to FIG.
[0050]
In the third embodiment, the solid reducing agent is stored in a rotatably supported cylindrical container. A drive gear 28 rotated by a motor 25 is provided adjacent to the container. A driven gear 29 that meshes with the driving gear 28 and rotates according to the rotation of the driving gear 28 is formed on the outer wall of the container that is the solid reducing agent storage unit 12 that stores the solid urea A.
[0051]
On the other hand, the bottom surface 12 a of the cylindrical storage container 12 is open and faces a circular receiving plate 32 fixed without rotating integrally with the storage container 12. The storage container 12 rotates with respect to the receiving plate 32 and is supported so as not to contact the receiving plate 32.
[0052]
Further, a pressurizing means 33 which rotates integrally with the container is provided. The pressurizing means 33 presses the upper surface of the solid urea A and presses it in the direction of arrow X.
The solid urea A rotates together with the storage container 12, but comes into contact with the receiving plate 32 by pressurization.
A fan-shaped opening 34 is provided on the surface of the receiving plate 32 from the center to the outer peripheral direction, and the cutter 30 is attached to the opening 34. The cutter 30 can contact and cut the solid urea A.
[0053]
With such a configuration, the storage container 12 is rotated by driving the motor 25, and the solid urea A is rotated integrally therewith. At this time, the solid urea A comes into contact with the receiving plate 32 and is cut by the cutter 30. The cut solid urea A temporarily falls into the reducing agent storage section 35, is heated and melted by the heater 40 provided in the reducing agent storage section 35, and is sent to the liquid urea storage chamber 13 through the communication passage 12e. Can be
[0054]
The operation and stop of the motor 25 are controlled by the ECU 16. The operation timing and time of the motor 25 can be appropriately set in consideration of the environment in the place where the engine 1 is used, seasonal factors, and the like.
[0055]
In this embodiment, the storage container 12 has a cylindrical shape and is configured to rotate together with the pressurizing means X. However, the following configuration may be employed.
The storage container 12 has a rotatable bottom, and the opening and the cutter as described above are provided in a part of the bottom surface, so that the solid urea A can be pressurized by a non-rotating pressurizing means. In this case, the solid urea A is pressurized toward the bottom surface of the storage container 12 by the pressurizing means. Then, a speed difference occurs between the solid urea A and the storage container 12, so that the solid urea A is cut by the cutter.
[0056]
According to this embodiment, a predetermined amount of solid urea A can be continuously and reliably taken out of the storage container 12.
[Fourth Embodiment]
A fourth embodiment of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described with reference to FIG.
[0057]
In the fourth embodiment, the solid reducing agent is stored in a rotatably supported cylindrical container. A drive gear 28 rotated by a motor 25 is provided adjacent to the container. A driven gear 29 that meshes with the driving gear 28 and rotates according to the rotation of the driving gear 28 is formed on the outer wall of the container that is the solid reducing agent storage unit 12 that stores the solid urea A.
[0058]
On the other hand, the bottom surface 12a of the cylindrical storage container 12 is open, and the bottom surface 12a faces the fixed circular receiving plate 32. The storage container 12 is rotatable by the driving of the motor 25 and is supported so as not to contact the receiving plate 32.
[0059]
A pressurizing means 33 for solid urea A is provided on the upper part of the storage container 12. The pressurizing means 33 presses the upper surface of the solid urea A, pressurizes it in the direction of arrow X, and rotates integrally with the storage container 12.
[0060]
The solid urea A rotates together with the storage container 12, but comes into contact with the receiving plate 32 by pressurization by the pressurizing unit 33.
A fan-shaped opening 34 is provided on the surface of the receiving plate 32 from the center to the outer periphery thereof, and the heater 31 is mounted around the opening 34. The heater 31 contacts the solid urea A and melts the solid urea A by the heat generated from the heater 31.
[0061]
With such a configuration, the storage container 12 rotates by driving the motor 25, and the solid urea A rotates integrally therewith. At this time, the solid urea A comes into contact with the receiving plate 32, melts and temporarily falls into the reducing agent storage section 34, and the liquefied urea flows out toward the liquid urea storage chamber 13.
[0062]
The operation and stop of the motor 25 are controlled by the ECU 16. The operation timing and period of the motor 25 can be appropriately set in consideration of the environment in the place where the engine 1 is used, seasonal factors, and the like.
[0063]
In the embodiment of the present invention, the storage container 12 has a cylindrical shape and is configured to rotate together with the pressurizing means. However, the following configuration may be used instead.
[0064]
The storage container 12 is rotatable and has a bottom, and the opening and the heater as described above are provided in a part of the bottom surface so that the solid urea A can be pressurized by a non-rotating pressurizing means. In this case, the solid urea A is pressurized toward the bottom surface of the storage container 12 by the pressurizing means. Then, a speed difference occurs between the solid urea A and the storage container 12, and the entire lower surface of the solid urea A is sequentially heated by the heater, uniformly melted, and flows out of the opening.
[0065]
According to this embodiment, the solid urea A can be taken out of the storage container 12 continuously and reliably while liquefying a predetermined amount.
[0066]
【The invention's effect】
According to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, the reducing agent is stored in a solid state in the solid reducing agent storage unit, and is taken out, stored in the molten reducing agent storage unit, and then supplied. In addition, the apparatus can be reduced in size and simplified, and the supply amount of the reducing agent can be controlled with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an exhaust gas purification apparatus according to a first embodiment of the present invention.
FIG. 2 is a view showing a schematic configuration of a storage container storing spherical solid urea.
FIG. 3 is a view showing a schematic configuration of a storage container storing a rod-shaped solid urea.
FIG. 4 is a schematic configuration diagram showing a state in which a carrying-out mechanism of solid urea is provided in a storage container.
FIG. 5 is a schematic configuration diagram showing a state in which another storage mechanism of solid urea is provided in the storage container.
FIG. 6 is a schematic configuration diagram showing a state in which another storage urea discharge mechanism is provided in the storage container.
FIG. 7 is a diagram showing a structure of an addition control valve for supplying a reducing agent.
[Explanation of symbols]
1 ... Diesel engine (internal combustion engine)
2 combustion chamber 3 air cleaner 4 intake pipe 5 fuel injection valve 6 piston 7 exhaust pipe (intake system)
8 NOx catalytic converter 9 exhaust pipe (exhaust passage)
DESCRIPTION OF SYMBOLS 10 ... Selective reduction type NOx catalyst 11 ... Reducing agent addition device 12 ... Storage container 13 ... Liquid urea storage chamber 14 ... Addition control valve (supply amount control means)
15 ... dehumidifying means 16 ... ECU
17 Remaining amount sensor 18 Temperature sensor 19 Gas temperature sensor containing catalyst 20 Air flow meter 21 NOx sensor 22 Meter panel 23 Alarm lamp 25 Motor 26 Gear 28 Drive gear 29 Driven gear 30 Cutter 31 Heater

Claims (3)

It provided in an exhaust gas passage of an internal combustion engine, a reducing or decomposing NOx selective reduction catalyst for NOx in the presence of ammonia from the reducing agent, and a solid reducing agent storage unit for storing the solid reductant, the solid reducing A molten reducing agent storage unit that heats and liquefies and stores the solid reducing agent guided from the agent storing unit, and a solid reduction unit that conveys the solid reducing agent stored in the solid reducing agent storage unit to the molten reducing agent storage unit Agent transporting means, and a molten reducing agent supply means for supplying the liquefied reducing agent liquefied in the molten reducing agent storage section to the exhaust gas passage upstream of the selective reduction type NOx catalyst ,
An exhaust gas purifying apparatus for an internal combustion engine, wherein a surface of the reducing agent is coated with a sticking inhibitor that prevents the reducing agents from sticking to each other. The solid reducing agent conveying means comprises a motor, a rotating member driven by the motor, according to claim 1, the rotating body is characterized in that unloading it in contact with the reducing agent from the solid reductant reservoir An exhaust gas purifying apparatus for an internal combustion engine according to claim 1. 3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1 , wherein the heat source for heating and liquefying the solid reducing agent in the molten reducing agent storage unit is an electric heater. 4.

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