JP4270428B2 - Automatic compounding device for reducing agent solution - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile in which exhaust gas purification means for reducing harmful nitrogen oxides (NOx) in exhaust gas to harmless gas using a selective catalytic reduction (SCR) catalyst and a reducing agent solution is provided in the exhaust system. The present invention relates to an automatic preparation device for a reducing agent solution.
[0002]
[Prior art]
Exhaust gas discharged from the engine of a diesel vehicle contains nitrogen oxides (NOx) in addition to carbon monoxide (CO) and hydrocarbons (HC).
A system for reducing this harmful nitrogen oxide (NOx) to a harmless gas includes a lean NOx catalyst, a selective catalytic reduction (SCR) catalyst, a lean NOx trap, etc. It is used.
[0003]
Among these systems, in a system using a selective catalytic reduction catalyst with high efficiency of NOx reduction reaction, urea, ammonia, or the like is used as a reducing agent for performing NOx reduction reaction in O 2 rich exhaust.
[0004]
When using urea that is easier to handle than ammonia, an exhaust gas purification chamber is provided in the middle of the exhaust muffler for automobile exhaust gas. The urea solution is put into the agent solution tank as a reducing agent solution, and this urea solution is injected into the exhaust pipe upstream of the exhaust gas purification chamber.
[0005]
In such a system, the NOx reduction reaction does not occur when the urea water runs out, but it does not cause any obstacles to the driving of the automobile, and it travels by discharging a large amount of harmful nitrogen oxides (NOx). Become.
[0006]
However, since the infrastructure for supplying urea water has not been developed at present, it is necessary to supply a relatively large amount when it can be supplied.
Therefore, a large-capacity reducing agent solution tank is required, it is difficult to secure a space for installing the reducing agent solution tank, and there is a disadvantage that the degree of freedom in designing the automobile is restricted.
In addition, there is a disadvantage that the weight of the automobile becomes heavy and the fuel consumption becomes worse.
[0007]
Further, even if the infrastructure for supplying the urea water is advanced, a reducing agent solution tank having a certain size is required, and the above-described disadvantage cannot be solved.
When the reducing agent solution tank has a small capacity, there is a disadvantage that the replenishment frequency of the reducing agent solution increases.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above, and in an automobile provided with exhaust gas purification means, it is easy to secure an installation space by making the reducing agent solution tank relatively small, and the weight can be made relatively light and low. An object of the present invention is to provide an automatic preparation apparatus for reducing agent solution that is fuel efficient and requires a relatively low replenishment frequency.
[0009]
[Means for Solving the Problems]
According to the present invention, an exhaust gas purification chamber (3) is provided in the middle of an exhaust gas pipe (2) for exhaust gas discharge of an automobile engine (1), and harmful nitrogen oxides are harmless to the exhaust gas purification chamber (3). A selective catalytic reduction catalyst for reducing the gas to a specific gas is housed, and the reducing agent solution (5) passes through a nozzle (3a) provided in a pipe (7) connected to the reducing agent solution tank (6). In the automatic preparation device for the reducing agent solution supplied to the exhaust gas pipe (2) upstream of the exhaust gas purification chamber (3), a water supply unit (10), a reducing agent metering unit (11), and a stirring unit (12), and the pipe (14) connected to the water tank (13) of the water supply unit (10) is connected to the stirring unit (12) via the second on-off valve (15), The reducing agent metering unit (11) includes a reducing agent tank (17) and a meter (18). And a discharge pipe (19) of the reducing agent tank (17) is connected to the meter (18), and the discharge pipe (19) is provided with a third on-off valve (20). (18) is a spring balance type equipped with a spring (18a), and when the level sensor (18b) detects that a certain amount of reducing agent has been supplied, the measured reducing agent is discharged to the stirring section (12). The stirring unit (12) includes a stirring tank (22) and a stirrer (23) having a stirring blade (23b) operated by a motor (23a), and is connected to the stirring tank (22). The pipe (24) is connected to the reducing agent solution tank (6), the pipe (24) is provided with a first on-off valve (25), and the reducing agent solution tank (6) is connected to the reducing agent solution tank (6). A liquid level sensor (9) for measuring the amount of the agent solution is provided. In response to signals from the liquid level sensor (9) of the reducing agent solution tank (6), the liquid level sensor (26) of the stirring tank (22), and the level sensor (18b) of the meter (18), A control device (28) for controlling the first on-off valve (25), the second on-off valve (15), and the motor (23a) is provided, and the control device (28) includes the reducing agent solution tank. It is determined whether or not the reducing agent solution (5) in (6) has been consumed and is below the liquid level sensor (9) of the reducing agent solution tank (6) (ST1). (25) is closed (ST2), the second on-off valve (15) is opened (ST3), and the water in the water tank (13) is supplied into the agitation tank (22) and the liquid level sensor of the agitation tank 22 is supplied. It was determined whether or not the liquid level had increased to (26) (ST4), and the liquid level increased. The second on-off valve (15) is closed (ST5), the third on-off valve (20) is opened (ST6), and urea in the reducing agent tank (17) is supplied to the meter (18) and supplied. When the spring (18a) is compressed by urea and the level sensor (18b) detects (ST7), the third on-off valve (20) is closed (ST8), and urea is fed from the measuring instrument (18) to the stirring tank (22). When the water and urea are supplied to the agitation tank (22), the motor (23a) is driven (ST10), and the agitation tank (22) is agitated by the agitation blade (23b) and agitated for a certain period of time. When the urea water becomes uniform (ST11), the first on-off valve (25) is opened (ST13), and the urea water in the stirring tank (22) is supplied to the reducing agent solution tank (6). Have.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a reducing agent solution automatic blending apparatus used in an automobile exhaust gas purification apparatus of the present invention will be described with reference to the drawings.
[0011]
As shown in FIG. 1, an exhaust gas purification chamber 3 of an exhaust gas purification means is provided in the middle of an exhaust gas exhaust pipe 2 of an automobile engine 1, and harmful nitrogen oxides (NOx) are harmless to the exhaust gas purification chamber 3. A selective catalytic reduction (SCR) catalyst that efficiently reduces the amount of the gas to the gas is housed.
[0012]
On the other hand, the automobile is provided with the automatic reducing device solution preparation device 4 of the present invention, and the reducing agent solution 5 prepared by the automatic preparation device 4 is supplied to the reducing agent solution tank 6. The pipe 7 connected to the reducing agent solution tank 6 is connected to a nozzle 3 a provided in the exhaust gas pipe 2 upstream of the exhaust gas purification chamber 3, and a pump 8 is interposed in the pipe 7.
The reducing agent solution tank 6 is provided with a liquid level sensor 9 for measuring the amount of the reducing agent solution.
[0013]
Note that urea water is optimal as the reducing agent solution 5 that efficiently reduces harmful nitrogen oxides (NOx) to harmless gas, but depending on the selective catalytic reduction catalyst housed in the exhaust gas purification chamber 3. Aqueous ammonia, alcohols or hydrocarbons may be used.
[0014]
The automatic blending device 4 that supplies the reducing agent solution 5 to the reducing agent solution tank 6 includes a water supply unit 10, a reducing agent metering unit 11, and a stirring unit 12.
A pipe 14 connected to the water tank 13 of the water supply unit 10 is disposed in the stirring unit 12, and an open / close valve 15 is interposed in the pipe 14. Water is supplied to the water tank 13 from a supply port 13a, and the amount of water is measured by a liquid level sensor 16 provided in the water tank 13.
[0015]
The reducing agent metering unit 11 includes a reducing agent tank 17 and a meter 18.
A discharge pipe 19 of the reducing agent tank 17 is connected to a measuring device 18, an opening / closing valve 20 is provided in the discharge pipe 19, and a level sensor 21 for measuring the amount of reducing agent is provided in the reducing agent tank 17.
[0016]
The measuring device 18 is a spring balance type. When the level sensor 18b detects that the spring 18a is compressed by the reducing agent supplied from the reducing agent tank 17 and a certain amount of reducing agent is supplied, the measured reducing agent is discharged. It is discharged to the stirring unit 12.
The stirring unit 12 includes a stirring tank 22 and a stirrer 23.
[0017]
A pipe 24 connected to the stirring tank 22 is connected to the reducing agent solution tank 6, and an open / close valve 25 is provided in the pipe 24.
The agitator 23 is provided in the agitation tank 22, and the agitating blade 23b is rotated by a motor 23a.
[0018]
When water is supplied from the water supply unit 10 and the liquid level sensor 26 detects the liquid level and the reducing agent is supplied from the reducing agent metering unit 11, the motor 23a is driven and stirred by the stirring blade 23b for a certain time. When the reducing agent solution becomes uniform after stirring, the on-off valve 25 is opened, and the reducing agent solution in the stirring tank 22 is supplied to the reducing agent solution tank 6.
[0019]
The liquid level sensors 9, 16, 26, the level sensors 18b, 21, the on-off valves 15, 20, 25, and the motor 23a are connected to the control device 28 by a signal line 27 so that control signals are exchanged. Yes.
The control device 28 is provided with a notification device 29 for informing the water supply to the water tank 13 and the supply of the reducing agent to the reducing agent tank 17.
[0020]
Next, based on the flowchart of FIG. 2, the operation | movement of the automatic compounding apparatus of the reducing agent solution of the exhaust gas purification means of the motor vehicle of the structure mentioned above is demonstrated in the example using urea as a reducing agent.
Water is put in the water tank 13 of the water supply unit 10 of the automatic blending device 4, urea powder as a reducing agent is put in the reducing agent tank 17 of the reducing agent metering unit 11, and the reducing agent solution tank 6 is automatically loaded. A reducing agent solution 5 prepared by the preparation device 4, that is, urea water is placed therein.
[0021]
During the driving of the engine 1, the pump 8 is driven, the urea water 5 in the reducing agent solution tank 6 is pumped by the pump 8, and is injected from the nozzle 3 a to the selective catalytic reduction catalyst in the exhaust gas purification chamber 3 through the pipe 7. The harmful nitrogen oxide (NOx) in the exhaust gas discharged from the muffler 2 of the engine 1 is reduced to a harmless gas and discharged into the atmosphere.
[0022]
When the urea water 5 in the reducing agent solution tank 6 is consumed and falls below the liquid level sensor 9 (ST1), the control device 28 closes the open / close valve 25 (ST2) and opens the open / close valve 15 (ST3).
When the on-off valve 15 is opened, water in the water tank 13 is supplied into the agitation tank 22, and when the liquid level in the agitation tank 22 rises and is detected by the liquid level sensor 26 (ST4), the on-off valve 15 closes ( ST5).
[0023]
Next, the opening / closing valve 20 is opened, urea in the reducing agent tank 17 is supplied to the meter 18, and when the spring 18 a is compressed by the supplied urea and the level sensor 18 b detects (ST 7), the meter 18 stirs. Urea is supplied to the tank 22 (ST9).
[0024]
When water and urea are supplied to the stirring tank 22, the motor 23a is driven (ST10), and the inside of the stirring tank 22 is stirred by the stirring blade 23b. When the urea water becomes uniform after stirring for a certain time (ST11), the on-off valve 25 is opened (ST13), and the urea water in the stirring tank 22 is supplied to the reducing agent solution tank 6.
[0025]
In addition, it is preferable that the concentration of urea water prepared by the automatic preparation device 4 is constant, and for example, 32.5%, which is the concentration at which urea water is most difficult to freeze, is good. However, the concentration may be high as long as the reaction efficiency is high according to the selective catalytic reduction catalyst.
[0026]
As described above, the automatic preparation device 4 makes urea water and supplies it to the reducing agent solution tank 6, and when the water in the water tank 13 decreases and becomes below the liquid level sensor 16, the control device 28 causes the alarm device 29 to call the water. Instruct and inform the supply. Similarly, when the reducing agent in the reducing agent tank 17 decreases and becomes equal to or lower than the level sensor 21, the control device 28 instructs the informing device 29 to supply the reducing agent and notifies it.
[0027]
As described above, as the reducing agent solution 5, ammonia water, alcohols, hydrocarbons, or the like is used in accordance with the selective catalytic reduction catalyst housed in the exhaust gas purification chamber 3, in addition to urea water. Also good.
[0028]
Moreover, although powdered urea is used as a reducing agent, a tablet or concentrated urea water may be used.
[0029]
Furthermore, urea is weighed by a spring balance type meter 18, but when powdered urea is used, urea may be weighed by a level sensor, and when a tablet urea is used, a specified number is supplied. You may make it do.
[0030]
Moreover, although the supply amount of water is measured by the water level sensor 26, it may be measured by the opening time of the on-off valve 15, or may be measured by providing a flow meter.
[0031]
【The invention's effect】
The effects of the automatic preparation device for the reducing agent solution of the present invention are listed below.
(1) Since the reducing agent solution is made from the water and the reducing agent by the automatic compounding device, the volume of the entire device becomes relatively small, the installation space can be easily secured, and the restrictions on the design of the automobile are reduced.
(2) The overall weight of the device is relatively light, resulting in a fuel-efficient vehicle.
(3) Although the frequency of water supply that is easily available is relatively high, the frequency of supply of the reducing agent that is difficult to obtain becomes relatively low.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an automatic preparation device for a reducing agent solution according to an embodiment of the present invention.
FIG. 2 is a flowchart of a control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust piping 3 ... Exhaust gas purification chamber 3a ... Nozzle 4 ... Automatic preparation apparatus 5 ... Reducing agent solution (urea water)
6 ... reducing agent solution tank 7, 14, 24 ... pipe 8 ... pump 9, 16, 26 ... liquid level sensor 10 ... water supply unit 11 ... reducing agent metering unit 12. .... Stirring unit 13 ... Water tanks 15, 20, 25 ... Open / close valve 17 ... Reducing agent tank 18 ... Metering device 19 ... Discharge pipe 21 ... Level sensor 22 ... Stirring Tank 23 ... Stirrer 27 ... Signal line 28 ... Control device 29 ... Alarm

Claims (1)

  An exhaust gas purification chamber (3) is provided in the middle of an exhaust gas pipe (2) for exhaust gas discharge of an automobile engine (1), and nitrogen oxides harmful to the exhaust gas purification chamber (3) are reduced to harmless gas. The selective catalytic reduction catalyst is stored, and the reducing agent solution (5) passes through the nozzle (3a) provided in the pipe (7) connected to the reducing agent solution tank (6), and the exhaust gas purification chamber ( 3) In the automatic preparation device for the reducing agent solution supplied to the exhaust gas pipe (2) on the upstream side of 3), a water supply unit (10), a reducing agent metering unit (11), and a stirring unit (12) are provided. The pipe (14) connected to the water tank (13) of the water supply unit (10) is connected to the stirring unit (12) via the second on-off valve (15), and the reducing agent metering unit ( 11) is composed of a reducing agent tank (17) and a meter (18). The discharge pipe (19) of the base agent tank (17) is connected to the meter (18), and the discharge pipe (19) is provided with a third on-off valve (20), and the meter (18) It is a spring balance type equipped with a spring (18a), and when the level sensor (18b) detects that a certain amount of reducing agent has been supplied, the measured reducing agent is discharged to the stirring unit (12). The stirring section (12) includes a stirring tank (22) and a stirrer (23) having a stirring blade (23b) operated by a motor (23a), and is connected to the stirring tank (22) ( 24) is connected to the reducing agent solution tank (6), the pipe (24) is provided with a first on-off valve (25), and the reducing agent solution tank (6) has an amount of reducing agent solution. A liquid level sensor (9) for measuring the reducing agent solution tank In response to signals from the liquid level sensor (9) of (6), the liquid level sensor (26) of the stirring tank (22), and the level sensor (18b) of the measuring instrument (18), A control device (28) for controlling the on-off valve (25), the second on-off valve (15), and the motor (23a) is provided, and the control device (28) is provided in the reducing agent solution tank (6). It is determined whether or not the reducing agent solution (5) of the reducing agent solution (5) is consumed and the liquid level sensor (9) of the reducing agent solution tank (6) is equal to or lower than (ST1). Close (ST2), open the second on-off valve (15) (ST3), and water in the water tank (13) is supplied into the agitation tank (22) to the liquid level sensor (26) of the agitation tank 22 It is determined whether or not the liquid level has increased (ST4). When the liquid level has increased, the second on-off valve ( 5) is closed (ST5), the third on-off valve (20) is opened (ST6), urea in the reducing agent tank (17) is supplied to the meter (18), and the spring (18a) is supplied by the supplied urea. Is compressed and the level sensor (18b) detects (ST7), the third on-off valve (20) is closed (ST8), and urea is supplied from the meter (18) to the stirring tank (22) (ST9). When water and urea are supplied to the agitation tank (22), the motor (23a) is driven (ST10), the agitation tank (22) is agitated by the agitation blade (23b), and the agitation tank (22) is agitated for a certain period of time so that the urea water is uniform. (ST11), the first on-off valve (25) is opened (ST13), and the urea water in the stirring tank (22) is supplied to the reducing agent solution tank (6). A device for automatically preparing a reducing agent solution.

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