JPH0579326A - Engine exhaust purifying device/method - Google Patents

Abstract

PURPOSE:To enable use of an electric system for heating a catalyst without any drastic change thereof when hydrocarbon included in the exhaust produced at the time of start of an engine is removed by the catalyst. CONSTITUTION:Catalytic converter rhodium 3 is placed in the exhaust passage 2 of a gasoline engine 1, while a fuel supplying device 4 and an air supplying device 5 are installed in the exhaust passage 2, which is located upstream from the catalytic converter rhodium 3. In addition, an electric heater 7 connected to a power supply 6 is installed in the exhaust gas entering part of the catalytic converter rhodium 3. When the engine 1 is started, the fuel and the air are supplied to the catalytic converter rhodium 3 from the fuel supplying device 4 and the air supplying device 5, respectively. In addition, the fuel is ignited by the electric heater 7, so that catalytic combustion may take place in the catalytic converter rhodium 3, thereby removing the hydrocarbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes an exhaust gas purification catalyst provided in an exhaust passage of an engine to discharge a large amount of unburned hydrocarbons or diesel engine discharged immediately after starting the engine. The present invention relates to an exhaust gas purification device and an exhaust gas purification method for removing particulates.

[0002]

2. Description of the Related Art In order to purify engine exhaust gas,
Usually, a catalyst is provided in the engine exhaust passage. However, the catalyst does not operate effectively until the temperature reaches about 300 ° C or higher. Therefore, when the exhaust gas temperature is low, that is, immediately after the engine is started, the exhaust gas cannot be sufficiently purified. On the other hand, immediately after the engine is started, the engine temperature is low and a large amount of unburned hydrocarbons are discharged. Therefore,
The catalyst is heated electrically to rapidly raise the catalyst temperature,
It has been proposed to remove unburned hydrocarbons emitted immediately after engine startup (eg SAE paper).
900503 and 900504, 1990).

A large amount of particulates are discharged from the diesel engine. Currently, there is no regulation for this particulate matter, but it is expected to be regulated in the near future. In addition, a large amount of particles in the trap
If the gas is trapped, it may clog and the exhaust gas may not flow. Therefore, a method has been proposed in which the particulates are collected by a trap and burned by the exhaust heat or the heat of the electric heater to regenerate the particulates.

[0004]

However, in the above prior art, since the catalyst is heated by electricity, a large amount of electric power is required. For example, when a 12V storage battery is used, a current of 200A or more is required. It Therefore, add a storage battery (12V or 48V storage battery),
It is necessary to develop new electric circuits. In particular, the addition of a storage battery causes an increase in weight, and when applied to an automobile, it causes a reduction in fuel consumption.

Also, when a large amount of particulates discharged from the diesel engine are collected by a trap provided on the catalyst and heated by an electric heater for catalytic combustion, a large amount of electric power is required. is necessary. In this case, the heat energy obtained by the combustion of the fuel in the engine is once converted into electric energy and then converted into heat energy again, which is not preferable because the energy efficiency is lowered.
Further, when exhaust heat is used, there is a drawback that the system becomes complicated such as using a heat medium.

An object of the present invention is to provide an engine exhaust gas purification apparatus and method that can obtain a sufficient exhaust gas purification capacity without modifying the electric system for heating the catalyst to a large scale.

[0007]

In order to achieve the above object, the present invention is an engine exhaust for heating an exhaust purification catalyst provided in an engine exhaust passage to remove unburned substances contained in the exhaust. In the purification device, fuel supply means for supplying fuel to the exhaust purification catalyst or the exhaust passage on the upstream side of the exhaust purification catalyst, and the supplied fuel is ignited to cause catalytic combustion in the exhaust purification catalyst. And ignition means.

Further, the present invention is an engine exhaust gas purification apparatus for heating an exhaust gas purification catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas. Supply means for supplying fuel to the exhaust passage on the upstream side of the exhaust catalyst, ignition means for igniting the supplied fuel to cause catalytic combustion in the exhaust purification catalyst, and the exhaust purification catalyst or exhaust purification Air supply means for supplying air to the exhaust passage on the upstream side of the exhaust catalyst to promote catalytic combustion in the exhaust purification catalyst.

Further, the present invention is an engine exhaust gas purification apparatus for heating a filter with catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, in the filter with catalyst or upstream of the filter with catalyst. A fuel supply means for supplying fuel to the exhaust passage on the side, and an ignition means for igniting the supplied fuel to cause catalytic combustion in the filter with catalyst.

Furthermore, the present invention is an engine exhaust gas purification apparatus for heating a filter with catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, in the filter with catalyst or upstream of the filter with catalyst. Side fuel supply means for supplying fuel to the exhaust passage, ignition means for igniting the supplied fuel to cause catalytic combustion in the filter with catalyst, and exhaust gas on the upstream side of the filter with catalyst or filter with catalyst Air supply means for supplying air to the passage to promote catalytic combustion in the filter with catalyst.

Further, according to the present invention, in an engine having an exhaust gas purification device in an exhaust passage, the exhaust gas purification device is:
It is equipped with any of the above engine exhaust gas purification devices. Further, according to the present invention, in an automobile equipped with an engine having an exhaust gas purification device in an exhaust passage, any one of the engine exhaust gas purification device is mounted as the exhaust gas purification device.

Further, according to the present invention, in an urban energy system in which an engine having an exhaust purification device in an exhaust passage is installed, any one of the above engine exhaust purification devices is installed as the exhaust purification device.

Further, the present invention is an engine exhaust purification method for removing unburned matter contained in exhaust gas by heating an exhaust purification catalyst provided in an engine exhaust passage, wherein the exhaust purification catalyst or exhaust gas is used. Fuel is supplied to the exhaust passage on the upstream side of the purification catalyst, and the fuel is ignited to cause catalytic combustion in the exhaust purification catalyst to remove unburned substances in the exhaust.

Further, the present invention is an engine exhaust purification method for removing unburned matter contained in exhaust gas by heating an exhaust purification catalyst provided in an engine exhaust passage, wherein the exhaust purification catalyst or the exhaust purification catalyst is used. The fuel is supplied to the exhaust passage on the upstream side of the purification catalyst, and the fuel is ignited to cause catalytic combustion in the exhaust purification catalyst, and the exhaust purification catalyst or the exhaust passage on the upstream side of the exhaust purification catalyst is provided. This is to remove unburned substances in the exhaust gas by supplying air to promote catalytic combustion in the exhaust gas purification catalyst.

[0015]

In order to proceed the catalytic combustion in the exhaust purification catalyst, it is necessary to heat the catalyst temperature to the ignition temperature or higher. According to the above configuration, the fuel supplied from the fuel supply means to the exhaust purification catalyst or the exhaust passage on the upstream side thereof is ignited by the ignition means and burned, and the combustion heat rapidly heats the catalyst to catalytically burn it. .. Then, if necessary, air is supplied from the air supply means to the exhaust gas purification catalyst or the exhaust passage on the upstream side thereof to advance catalytic combustion. In this case, an electric heater, a discharge tube, etc. are required as the ignition means, but since the main heat source is just the combustion heat of the fuel from the fuel supply means, the required power is reduced compared to the conventional method using electricity as the main heat source. It can be extremely small. Further, the ignition temperature can be lowered depending on the ratio of fuel and air, and in that case, the required power can be further reduced.

Further, in the diesel engine, if a filter (trap) provided with a catalyst is provided in the exhaust passage, the particulates discharged from the diesel engine are collected by the filter after a certain period of time. To be done. Therefore, fuel is supplied from the fuel supply means and air is supplied from the air supply means to the filter, the fuel is ignited by the ignition means, the temperature of the filter is raised by the heat of combustion, and the collected particulates are burned and removed. be able to. By repeating this, it becomes possible to always remove the particulates. There is 1 oxygen in the exhaust gas.
Since the content is about 0%, the air supply device may be unnecessary.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of an engine exhaust gas purification apparatus showing Embodiment 1 of the present invention. In the figure, a three-way catalyst (volume 1.0 liter) 3 usually mounted on an automobile is arranged in an exhaust passage 2 of a gasoline engine 1, and a fuel supply device is provided in an exhaust passage 2 upstream of the three-way catalyst 3. 4 and an air supply device 5 are attached. An electric heater 7 connected to a power source 6 is attached to the exhaust gas inlet of the three-way catalyst 3. The air supply device 5 may be omitted.

In the engine exhaust gas purification apparatus having the above-mentioned structure, the electric heater 7 is heated by the power source 6 before the gasoline engine 1 is started, and at the same time as the startup, the fuel (gasoline) is supplied at a rate of 4 g / min by the fuel supply device 4. Air that was supplied and was in excess of the stoichiometric air-fuel ratio was supplied by the air supply device 5 for 2 minutes. Then, a thermocouple was inserted in the center of the catalyst to measure the catalyst temperature. Fig. 2 shows the change over time in the catalyst temperature at that time.
Shown in. Further, FIG. 3 shows the change over time in the conversion rate of hydrocarbons in the exhaust gas.

The hydrocarbon conversion rate was determined by ((concentration in exhaust gas)-(concentration at catalyst outlet)) / (concentration in exhaust gas) × 100, ignoring the supplied fuel. It can be seen from FIG. 2 that the catalyst temperature reaches about 300 ° C. about 30 seconds after the engine is started, the temperature rises until the fuel supply is stopped after 2 minutes, and then the temperature decreases. Further, looking at the hydrocarbon conversion rate in FIG. 3, it can be seen that a hydrocarbon conversion rate of about 60% is exhibited from 15 seconds after starting. In FIG. 2, the reason why the hydrocarbon conversion rate of about 60% was obtained even though the catalyst temperature after 15 seconds was 300 ° C. was that the temperature was the value inside the catalyst, and the exhaust gas inlet temperature was It is presumed that the temperature is high. As described above, it is understood that a high hydrocarbon conversion rate can be obtained immediately after the engine is started by using the combustion heat generated when the fuel is catalytically combusted as the heating source.

In the comparative examples shown in FIGS. 2 and 3, the fuel supply device 4, the air supply device 5, the power source 6 and the electric heater 7 in FIG. 1 are removed, and the catalyst temperature and the hydrocarbon conversion rate are measured. Is. The change in catalyst temperature with time is shown in FIG. 2, and the change in hydrocarbon conversion rate with time is shown in FIG. It can be seen that the hydrocarbon conversion is very low due to the lower catalyst temperature compared to the results of the examples.

Although the electric heater 7 is attached to the exhaust gas inlet of the three-way catalyst 3 in this embodiment, the electric heater 7 may be attached inside the three-way catalyst 3. Alternatively, the fuel supply device 4 and the air supply device 5 may be directly attached to the three-way catalyst 3 so that fuel and air are supplied to the three-way catalyst 3 without passing through the exhaust passage 2. In addition to gasoline, light oil, kerosene, LPG, or alcohol can be used as the fuel.

(Embodiment 2) FIG. 4 is a schematic configuration diagram of an engine exhaust gas purification apparatus showing Embodiment 2 of the present invention. In the figure, in the exhaust passage 12 of the diesel engine 11, a filter with a catalyst carrying a combustion catalyst (volume: 1.0 liter)
13 is arranged, and the fuel supply device 14 is attached to the exhaust passage 12 on the upstream side of the filter 13 with catalyst. At the exhaust gas inlet of the filter 13 with catalyst, the power source 1
An electric heater 17 connected to 6 is attached.

In the engine exhaust gas purifying apparatus having the above-mentioned structure, the diesel engine 11 is operated for 1 hour to collect the particulates in the filter 13 with catalyst, and then the power source 1
The electric heater 17 is energized from 6 and, after 5 minutes, fuel (light oil)
Was supplied at a rate of 4 g / min. Diesel engine 11
Since the exhaust gas of No. 1 contains sufficient oxygen, air was not supplied. After supplying the fuel for 2 minutes and burning it, the filter 13 with the catalyst was taken out and observed. As a result, almost no particulates trapped were observed.
It was found that the particulates were burned off.

Although the electric heater 17 is attached to the exhaust gas inlet portion of the filter 13 with catalyst in this embodiment, the electric heater 17 may be attached inside the filter 13 with catalyst. Further, the fuel supply device 14 may be directly attached to the filter 13 so that the fuel is supplied to the filter 13 without passing through the exhaust passage 12. Further, an air supply device for supplying air to the filter with catalyst 13 or the exhaust passage 12 on the upstream side thereof may be provided. In addition to light oil, gasoline, kerosene, LPG, or alcohol can be used as the fuel.

The engine exhaust emission control devices of the two embodiments described above can be applied to automobiles. Actually, the engine exhaust gas purification apparatus of Example 1 was mounted as it is on an automobile having a displacement of 2 liters. Gasoline was supplied from the vehicle-mounted gasoline tank to the exhaust passage 2 by the fuel supply device 4. An ordinary air pump was used as the air supply device. As the power source 6 for energizing the electric heater 7, an ordinary 12V storage battery mounted on the vehicle was used. As a result, it became clear that a high hydrocarbon conversion rate was obtained immediately after the engine was started.

A diesel engine equipped with the engine exhaust gas purification apparatus of Example 2 was used to form a city energy system for cogeneration. Then, a device similar to that of Example 2 was attached to the exhaust passage of the engine, and a test was conducted in the same manner. As a result, as in the case of the second embodiment,
The collected particulates were hardly observed, and it was confirmed that the particulates were burned and removed.

[0028]

As described above, according to the engine exhaust gas purifying apparatus of the present invention, the catalyst can be heated by the combustion heat of the fuel when the engine is started, and the temperature can be quickly raised to the catalyst operating temperature. It is possible to easily remove a large amount of hydrocarbons discharged at the time of start-up and particulates discharged from a diesel engine without significantly changing the conventional electric system.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an engine exhaust gas purification device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change over time in catalyst temperature.

FIG. 3 is a diagram showing a change with time of a hydrocarbon conversion rate.

FIG. 4 is a schematic configuration diagram of an engine exhaust gas purification device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Gasoline engine 2,12 Exhaust passage 3 Three-way catalyst 4,14 Fuel supply device 5 Air supply device 6,16 Power supply 7,17 Electric heater 11 Diesel engine 13 Filter with catalyst

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location F01N 3/24 L 9150-3G (72) Inventor Shinichi Ichikawa 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Co., Ltd. Hitachi Research Laboratory, Hitachi, Ltd. (72) Noriko Watanabe 4026, Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (15)

[Claims] 1. An engine exhaust purification device for heating an exhaust purification catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, wherein the exhaust purification catalyst or the exhaust purification catalyst upstream side. Of the exhaust gas, and an ignition means for igniting the supplied fuel to cause catalytic combustion in the exhaust gas purification catalyst. .. 2. An engine exhaust purification apparatus for heating an exhaust purification catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, wherein the exhaust purification catalyst or the exhaust purification catalyst upstream side. Fuel supply means for supplying fuel to the exhaust passage, ignition means for igniting the supplied fuel to cause catalytic combustion in the exhaust purification catalyst, and the exhaust purification catalyst or the exhaust purification catalyst upstream side And an air supply unit that supplies air to the exhaust passage to promote catalytic combustion in the exhaust gas purification catalyst. 3. The engine exhaust gas purification device according to claim 1, wherein the ignition means is an electric heater. 4. The engine exhaust purification system according to claim 1, wherein the ignition means is provided inside the exhaust purification catalyst or at an exhaust gas inlet portion of the exhaust purification catalyst. An engine exhaust gas purification device. 5. An engine exhaust gas purification apparatus for heating a filter with catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, wherein the filter with catalyst or the exhaust passage upstream of the filter with catalyst is provided. An engine exhaust gas purification apparatus comprising: a fuel supply unit configured to supply fuel to the engine; and an ignition unit configured to ignite the supplied fuel to cause catalytic combustion in the filter with catalyst. 6. An engine exhaust purification device for heating a filter with catalyst provided in an engine exhaust passage to remove unburned matter contained in exhaust gas, wherein the filter with catalyst or the exhaust passage upstream of the filter with catalyst is provided. Fuel supply means for supplying fuel to the fuel, ignition means for igniting the supplied fuel to cause catalytic combustion in the catalyst-equipped filter, and air for the catalyst-equipped filter or the exhaust passage upstream of the catalyst-equipped filter. And an air supply unit that supplies the air to promote catalytic combustion in the filter with catalyst. 7. The engine exhaust gas purification device according to claim 5, wherein the ignition means is an electric heater. 8. The engine exhaust gas purification apparatus according to claim 5, wherein the ignition means is provided inside the filter with catalyst or at an exhaust gas inlet portion of the filter with catalyst. Engine exhaust gas purification device. 9. The engine exhaust gas purification apparatus according to claim 1, 2, 5 or 6, wherein the fuel is gasoline, light oil, kerosene, city gas, or L.
An engine exhaust gas purification device characterized by using PG or alcohol. 10. An engine having an exhaust gas purification device in an exhaust passage, wherein the engine exhaust gas purification device according to any one of claims 1 to 9 is mounted as the exhaust gas purification device. 11. An automobile equipped with an engine having an exhaust gas purification device in an exhaust passage, wherein the engine exhaust gas purification device according to any one of claims 1 to 9 is mounted as the exhaust gas purification device. Automobile. 12. A city energy system in which an engine having an exhaust purification device in an exhaust passage is installed, wherein the engine exhaust purification device according to any one of claims 1 to 9 is installed as the exhaust purification device. And the city energy system. 13. An engine exhaust purification method for removing unburned matter contained in exhaust gas by heating an exhaust purification catalyst provided in an engine exhaust passage, the exhaust purification catalyst or an exhaust purification catalyst upstream. A method for purifying engine exhaust gas, wherein unburned matter in exhaust gas is removed by supplying fuel to the exhaust passage on the side and igniting the fuel to cause catalytic combustion in the exhaust gas purification catalyst. 14. An engine exhaust purification method for removing unburned matter contained in exhaust gas by heating an exhaust purification catalyst provided in an engine exhaust passage, the exhaust purification catalyst or an exhaust purification catalyst upstream. Fuel is supplied to the exhaust passage on the side, the fuel is ignited to cause catalytic combustion in the exhaust purification catalyst, and air is supplied to the exhaust purification catalyst or the exhaust passage on the upstream side of the exhaust purification catalyst. An engine exhaust gas purification method for removing unburned matter in exhaust gas by promoting catalytic combustion in the exhaust gas purification catalyst. 15. The engine exhaust gas purification method according to claim 13 or 14, wherein the fuel supplied to the exhaust gas purification catalyst is ignited by an electric heater.