JPH05321634A - Particulate treating device of diesel engine - Google Patents

Abstract

PURPOSE:To carry out combustion at a low temperature efficiently by supplying water to new air and also making corona discharge so as to generate an OH radical, in the case of burning particulates by heating while supplying the new air in the regeneration of a trap. CONSTITUTION:Plural particulate traps 4 (a, b) are provided in the exhaust gas passage 2 of a diesel engine 1 so that the particulates contained in the exhaust gas can be caught. New air is supplied from a new air supply means 6 into the traps 4 so that the combustion of the particulate can be expedited. Further, the traps 4 are heated by respective heating bodies 8 (a, b) so that the particulates can be regenerated by combustion. In the above device, water is poured from a water pouring means 10 into the new air in a mist form. A molecule H2O constituting the water is decomposed and an OH radical is generated by corona discharge to the new air in which the water is poured by an OH radical generation means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate treatment device for trapping particulates contained in exhaust gas discharged from a diesel engine and distributing only the gas component, and more particularly to burning the trapped particulates. The present invention relates to improvement of means for regenerating a particulate trap.

[0002]

2. Description of the Related Art In particular, in the case of a diesel engine often used for buses and trucks, the exhaust gas produced by driving the engine contains a large amount of particulates.

Most of the particulates are composed of soot, which is exhaust particulates, and a small amount of HC (hydrocarbons). If they are discharged to the outside of the vehicle as they are, they cause pollution. Therefore, they are purified by some means. Must. Conventionally, a particulate processing device as shown in FIG. 4 is used. Reference numeral 1 in the figure denotes a diesel engine, to which an exhaust gas passage 2 for discharging exhaust gas generated by the combustion action to the outside is connected.

The midway portion of the passage 2 is branched via the switching means 3 into the two branch paths 2a and 2b, and the particulate traps 4a and 4b are respectively provided in the branch paths 2a and 2b.
b is provided. The wake side of these traps 4a and 4b is rejoined into one system, and is opened to the atmosphere via an exhaust muffler 5.

Further, each of the particulate traps 4a,
Fresh air supply means 6 is connected to the upstream side of 4b. It is equipped with a blower 7 for each of the branches 2a, 2
Fresh air, which is external air, is forcibly supplied and mixed into the exhaust gas guided to b. Heating heaters 8a and 8b, which are heating bodies, are provided on the inlet sides of the particulate traps 4a and 4b, respectively.
b is heated to a high temperature.

Since the particulate treatment apparatus is constructed in this manner, one particulate trap, for example, 4a, traps the particulates contained in the exhaust gas and reduces the release to the outside. When the particulate trap 4a is used for a predetermined period, the trapped particulates easily cause clogging and lose the trapping effect. Therefore, the trapping action of particulates is continued by switching the exhaust gas to another trap 4b. For the trap 4a that has been clogged, the blower 7 is driven to supply fresh air, and the heater 8a heats up to raise the temperature of the trap 4a.

The particulates trapped in the trap 4a are efficiently burned by the supply of a sufficient amount of oxygen and high heat, so that the particulate trap 4a is regenerated.

[0008]

As described above, in the rapid and reliable regeneration of the particulate trap 4a, it is sufficient to burn the trapped particulates efficiently in a short time. It is better to supply the fresh air and to raise the temperature of the trap 4a itself.

With respect to the increase in the supply amount of fresh air, there is no problem since it is sufficient to secure the blown air amount of the blower 7 under the optimum condition. It is possible to raise the temperature of the trap 4a by increasing the amount of heat generated by the heater 8a, and there is no hindrance to the technical solution.

However, the particulate traps 4a and 4b are usually made of ceramic and have the property of locally expanding and becoming brittle when exposed to high heat. Therefore, even if a slight impact is applied in this state, it is easily broken partially and leads to total destruction.

At present, it is extremely difficult to substitute another material having heat resistance, and it is necessary to develop a means for achieving efficient particulate combustion while using this material as it is.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to achieve rapid combustion of particulates in a relatively low temperature state to prevent damage to the particulate trap. The present invention aims to provide a particulate treatment device for a diesel engine that can be regenerated without any problems, achieve highly reliable regeneration, improve durability, and reduce the capacity of a heating element.

[0013]

In order to achieve the above object, a first aspect of the present invention is provided in a midway portion of an exhaust gas passage for guiding exhaust gas generated by driving a diesel engine to the outside. A particulate trap that traps particulates, which are exhaust particulates contained in the exhaust gas, and discharges them in a gas-only state, and fresh air that supplies fresh air to this particulate trap to facilitate combustion of the trapped particulates. Particulate treatment provided with a supply means and a heating body that heats the particulate trap to which fresh air is supplied from the fresh air supply means and burns the particulate trapped therein to regenerate the particulate trap. In the device, means for injecting water into the fresh air supplied from the fresh air supply means in the form of a spray,

A corona discharge is generated with respect to the fresh air into which the water has been injected to dissociate the molecule H ₂ O constituting the water.
A particulate matter treatment apparatus for a diesel engine, comprising: an OH radical generating means for producing H radicals and burning the particulates in a relatively low temperature state.

A second aspect of the present invention is a particulate matter, which is an exhaust particulate contained in the exhaust gas, provided in the middle of the exhaust gas passage for guiding the exhaust gas generated by the driving of the diesel engine to the outside. Particulate trap that traps and discharges only the gas in the state, and fresh air supply means that supplies fresh air to this particulate trap to facilitate combustion of the trapped particulate and new air supply means. In the particulate treatment apparatus, which comprises heating the particulate trap that has been supplied with air, and heating the particulate trap to burn the particulate trap to regenerate the particulate trap,

A corona discharge is applied to the fresh air supplied from the fresh air supply means to dissociate the molecule O ₂ in the air to generate an O radical, which burns particulates at a relatively low temperature. A particulate treatment device for a diesel engine, comprising: a generating unit.

[0017]

In the first aspect of the invention, corona discharge is applied to fresh air injected in a mist state to generate OH radicals by dissociation of H2O to oxidize particulates. Burn in a very low temperature.

In the second aspect of the invention, the fresh air supplied is subjected to a corona discharge to generate O radicals by the dissociation of O2 molecules to oxidize the particulates and burn them at a relatively low temperature.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a particulate treatment device of a diesel engine.

The difference from the conventional one is that a water injection means 10 and an OH radical generation means 11 are newly provided, and other configurations are the same as those previously described with reference to FIG. Since they are good, the same numbers are given to the same parts and a new description is omitted. Details of the water injection means 10 and the OH radical generation means 11 are as shown in FIG.

That is, on the suction side, which is the upstream side of the blower 7 constituting the fresh air supply means 6, an injection nozzle 12 communicating with a pump (not shown) constituting the water injection means 10 is provided.

From the spray nozzle 12, water is atomized and sprayed on the fresh air to mix the fresh air and the mist-like water droplets. By the action of the blower 7, the water droplets are made into a finer mist and are sent together with fresh air.

On the blast side, which is the downstream side of the blower 7,
Chamber 13 constituting the OH radical generating means 11
Is provided. An electrode portion (not shown) is provided in the chamber 13 and is electrically connected to a high voltage AC power source 14 outside the chamber 13.

That is, when an AC high voltage is applied from the high voltage AC power supply 14 to the electrode portion in the chamber 13, corona discharge (also called silent discharge) is generated in the chamber 13. Specifically, in the chamber 13, a discharge is caused by interposing a dielectric in the discharge path and applying an AC voltage to the gap, and at this time, the dielectric suppresses the transfer of the discharge to an arc. In addition, it serves to prevent the discharge from being concentrated at a specific place.

The particulate treatment device is constructed in this way, and all of the exhaust gas generated when the diesel engine 1 is driven is sent to the exhaust gas passage 2. From the midway portion of this passage 2, one branch passage, for example, 2a, is branched to be guided to the particulate trap 4a, and the particulates contained in the gas can be efficiently captured. The particulate trap 4a is likely to be clogged with the trapped particulates and loses the trapping effect after being used for a predetermined period. Therefore, the trapping action of particulates is continued by switching the exhaust gas to another trap 4b. The blower 7 is driven to supply fresh air to the clogged trap 4a, and water is atomized and sprayed from the spray nozzle 12 to be mixed with fresh air. These air-fuel mixtures are sent to the chamber 13 to be filled therewith, and undergo corona discharge due to the application of an AC high voltage. By this corona discharge, the molecule H ₂ O forming water in the air containing water in the chamber 13 is dissociated to generate an OH radical (group).

A radical is a group of atoms that can move from one compound to another without changing during a chemical reaction. Alternatively, it may be used in a broader sense to refer to a group of atoms that are often present in various compounds.

Fresh air to which such OH radicals have been added exits from the chamber 13 and is in the particulate trap 4.
led to a. Here, the heater 8a generates heat, but the addition of OH radicals causes the particulates to burn at a relatively low temperature.

That is, the particulates trapped in the trap 4a receive a sufficient amount of oxygen to which OH radicals have been added, and efficiently burn at a relatively low temperature, so that the particulate trap 4a is quickly regenerated. Can be achieved.

Since it is not necessary to expose each of the particulate traps 4a and 4b to a high temperature, problems such as breakage and breakage can be suppressed and durability is improved. In addition, the heating capacity of each heater 8a, 8b can be reduced. Figure 3
Is an example in which the O radical generating means 20 is provided on the blower side of the blower 7, which is the downstream side of the fresh air supply means 6.

In this case, a chamber 21 which constitutes the O radical generating means 20 is provided, and an electrode portion (not shown) is provided in the chamber 21.
It is electrically connected to a high-voltage AC power source 22 outside.

From the high voltage AC power source 22 to the chamber 21
When an AC high voltage is applied to the inner electrode part, corona discharge (also called silent discharge) is generated in the chamber 21, as in the case described above. Then, the blower 7 is driven to supply fresh air to the particulate trap 4a that has been clogged with the captured particulates. Fresh air is sent to the chamber 21 to fill it up,
In addition, the molecule O ₂ in the air is dissociated by receiving the corona discharge due to the application of the AC high voltage, and the O radical (group) is generated.

Such fresh air added with O radicals is guided to the particulate trap 4a. Here, the heater 8a generates heat, but the addition of O radicals causes the particulates to burn at a relatively low temperature.

That is, the particulates trapped in the trap 4a receive a sufficient amount of oxygen to which O radicals are added, and efficiently burn at a relatively low temperature,
Therefore, the particulate trap 4a can be quickly regenerated.

Since it is not necessary to expose the particulate traps 4a and 4b to a high temperature, the durability is improved, and even if the heating capacity of the heaters 8a and 8b is reduced, there is no problem. Is the same as that described above.

[0035]

As described above, according to the first aspect of the present invention, OH radicals are generated by performing corona discharge with respect to fresh air into which atomized water is injected. According to the second invention, O radicals are generated by performing corona discharge on fresh air.

In any of the inventions, it is possible to cause the particulates to burn at a relatively low temperature and to promptly regenerate the particulate trap. Therefore, the highly reliable particulate trap can be regenerated without being damaged, and the durability can be improved and the capacity of the heating element can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a particulate treatment device for a diesel engine according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part of the apparatus in the same embodiment.

FIG. 3 is a vertical cross-sectional view of a main part of the device in another embodiment.

FIG. 4 is a schematic configuration diagram of a particulate treatment device for a diesel engine according to a conventional example of the present invention.

[Explanation of symbols]

1 ... Diesel engine, 2 ... Exhaust gas passage, 4a, 4
b ... particulate trap, 6 ... fresh air supply means, 8
a, 8b ... Heating body (heating heater), 10 ... Water injection means,
11 ... OH radical generating means, 20 ... O radical generating means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location F01N 3/04 A (72) Inventor Mitsugu Anraku 5-3-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors Industrial Co., Ltd. (72) Inventor Toshio Nagase 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Co., Ltd. (72) Inventor Yoharu Yamada 10 Okura-cho, Nakahara-ku, Kawasaki-shi, Kanagawa Mitsubishi Motors Engineering Co., Ltd. Tokyo office

Claims (2)

[Claims] 1. An exhaust gas passage, which guides exhaust gas generated when a diesel engine is driven to the outside, is provided in the middle of the exhaust gas passage to trap particulates, which are exhaust particulates contained in the exhaust gas, to collect only the gas. The particulate trap that is discharged in the state, the fresh air supply means that supplies the fresh air to the particulate trap to facilitate the combustion of the captured particulates, and the fresh air is supplied from this fresh air supply means. In a particulate treatment apparatus comprising a heating body for heating the particulate trap and burning the particulate trap captured here to regenerate the particulate trap, the fresh air water supplied from the fresh air supply means is supplied. Water is formed by means of spraying and injecting it, and corona discharge is made to the fresh air into which this water is injected. Dissociating molecular H ₂ O to to generate OH radicals, relatively particulates processing apparatus for a diesel engine, characterized by comprising the OH radical means to burn the particulates in the cold state. 2. An exhaust gas passage, which guides exhaust gas generated by driving a diesel engine to the outside, is provided in the middle of the exhaust gas passage to trap particulates, which are exhaust particulates, contained in the exhaust gas. The particulate trap that is discharged in the state, the fresh air supply means that supplies the fresh air to the particulate trap to facilitate the combustion of the captured particulates, and the fresh air is supplied from this fresh air supply means. In a particulate treatment apparatus comprising a heating body for heating the particulate trap and burning the particulate trap captured therein to regenerate the particulate trap, a corona is added to the fresh air supplied from the fresh air supply means. by dissociating molecular O ₂ in the air to generate O radicals by forming the discharge, a relatively low temperature O to burn the particulates
A particulate treatment device for a diesel engine, comprising a radical generating means.