JPH0791328A - Egr gas electrifying device - Google Patents

Abstract

PURPOSE:To prevent sticking of an exhaust particulate by generating corona discharge between both positive and negative electrodes arranged in an intake air passage, and collecting dust by attracting this exhaust particulate to a positive electrode plug arranged on a cylinder head after soot and sulfide in the exhaust particulate in passing EGR gas are electrified negative. CONSTITUTION:In an EGR gas electrifying device 8, plural positive electrodes 12 are arranged in an insulating cylinder body 10 in the same shape with an intake air passage 2 of an engine 3 so as to surround a single negative electrode (discharge electrode) 11, and high voltage DC electric power supply 13 is connected to these, and an electrifying part is constituted. On the other hand, a positive electrode plug 9 is installed on a cylinder head 3a of the engine 3, and this positive electrode 9a is connected to a positive electrode of the high voltage DV electric power supply 13, and a dust collecting part is constituted. Corona discharge is generated between the respective electrodes 11 and 12, and after an exhaust particulate in EGR gas is electrified negatively by an anion generated by this, and it is attracted to the positive electrode plug 9, and dust is collected. Thereby, the exhaust particulate can be prevented from sticking to the engine 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR gas charging device for charging and removing soot and sulfide as exhaust particulates in EGR gas.

[0002]

2. Description of the Related Art EGR (Exhaust Gas Recirculation) reduces a maximum temperature at the time of combustion and reduces NOx generation by recirculating a part of exhaust gas to an intake system and mixing it into an intake mixture. Therefore, there is a remarkable effect in reducing NOx, especially in a diesel engine.

[0003]

However, this EGR
Has the drawback that it significantly deteriorates the durability of the engine. The cause is that the exhaust gas contains soot (foreign matter) as exhaust particulates and sulfides, which flow into the cylinder together with the intake air-fuel mixture and touch the sliding parts such as the cylinder liner. It dissolves in the oil that forms the. The oil containing the soot and sulfide is scraped off by the piston ring by the reciprocating motion of the piston, enters the oil pan, and circulates in various parts of the engine. As a result, there is a problem that the corrosion and wear of the cylinder liner and the wear of the piston ring are accelerated, and the durability of the engine is reduced.

The present invention has been made in view of the above points, and removes soot, sulfide, and the like as exhaust particulates in EGR gas to prevent them from adhering to a cylinder liner, piston ring, or the like, and It is an object of the present invention to provide an EGR gas charging device designed to improve durability.

[0005]

To achieve the above object, according to the present invention, an EGR control means for recirculating a part of exhaust gas to an intake system to reduce NOx, and the engine Of the intake passage, a tubular body connected to a downstream side of the exhaust gas introduction hole of the intake passage and forming a part of the intake passage by an insulating member, and an axial direction at the center of the tubular body. At least a first electrode that is disposed and has a base end supported by the tubular body; and a second electrode that has a base end supported by the tubular body and is spaced apart and opposed to the first electrode in the tubular body; Power supply means having a negative electrode connected to the base end of the first electrode and the intake passage and a positive electrode connected to the second electrode, and the first and second
Charging means for applying a high-voltage DC voltage to the electrodes to generate corona discharge between these electrodes, and is electrically insulated and supported by the cylinder head of the engine and faces the cylinder and is connected to the positive electrode of the power supply means. A structure comprising a positive electrode and an engine body connected to the negative electrode of the power supply means, and a dust collecting means for sucking fine particles in the negatively charged exhaust gas around the positive electrode. is there.

[0006]

In the charging means, the first electrode serves as a discharge electrode and corona discharge is generated between the first electrode and the second electrode, and the negative ions generated from the first electrode move toward the second electrode. To do.
When the EGR gas passes through the charging means, soot and sulfide as exhaust particulates are negatively charged. The negatively charged soot or sulfide receives the repulsive force of Coulomb from the intake passage held at a negative potential, and flows into the cylinder of the engine without adhering to the intake passage. The engine is held at a negative potential together with the intake passage, and the positive electrode of the dust collecting means of the cylinder head is provided facing the inside of the cylinder. Therefore, the negatively charged soot and sulfides are subjected to Coulomb's repulsive force in the cylinder and also attracted to the positive electrode to be collected by the positive electrode. This prevents soot and sulfide in the EGR gas from adhering to the cylinder liner, piston ring, and the like.

[0007]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an outline of an EGR intake engine to which the present invention is applied. An air cleaner 1 is connected to an intake port of an engine 3 via an intake passage 2, and an exhaust port of the engine 3 is connected via an exhaust passage 4. It is connected to the muffler 5. The intake passage 2 and the exhaust passage 4 are connected by a bypass passage 6, and an EGR control valve 7 is connected to the bypass passage 6. A charging device 8 is connected to the intake passage 2 at the downstream side of the connection portion with the bypass passage 6. Further, the engine 3 is provided with a positive electrode plug 9.

As shown in FIG. 2, the charging device 8 includes a cylindrical body 10 having the same shape as the intake passage 2, a negative electrode 11, and a plurality of positive electrodes 1.
2 and a high-voltage DC power supply 13, and a cylinder 1
0 is formed of an insulating member. The negative electrode 11 is
It is arranged at the center of the tubular body 10 along the axial direction, and the base end is supported by penetrating a small hole formed in the side wall of the tubular body 11 and extends to the outside. The positive electrode 12 is the cylindrical body 1.
A plurality of small holes which are arranged in a circle having a predetermined radius centered on the negative electrode 11 at an equal interval, are connected to each other at their base ends and are combined into one, and are bored in the side wall of the cylindrical body 10. Is supported through and extends to the outside. The positive electrodes 12 may be diagonally arranged with the negative electrode 11 as the center.

The base end of the negative electrode 11 is connected to the negative electrode of the power supply 13, and the base end of each positive electrode 12 is connected to the positive electrode of the power supply 13. The negative electrode of the power source 13 is connected to the intake passage 2 and is grounded (vehicle body ground).
The intake passage 2 and the engine 3 are each formed of a metal member and are fixed by bolts. Therefore, the engine 3 is also connected to the negative electrode of the power supply 13. The negative electrode 11 is a discharge electrode (hereinafter referred to as "discharge electrode 11"), an unequal electric field is formed between the discharge electrode 11 and each positive electrode 12, and corona discharge occurs between these electrodes. It is like this.

The positive electrode plug 9 is mounted on the cylinder head 3a of the engine 3 as shown in FIG. 2, and the tip of the positive electrode 9a is arranged so as to face the cylinder liner 3c of the cylinder block 3b. This positive electrode plug 9 has, for example, a structure in which the ground electrode 9b indicated by the chain double-dashed line is removed from the spark plug of the gasoline engine which has self-cleaning properties for soot attached by combustion heat as shown in FIG. . The positive electrode 9a is connected to the positive electrode of the high-voltage DC power supply 13, and a high voltage is applied to it like the positive electrode 12.

The positive electrode plug 9 intentionally deteriorates the cooling performance of the insulator so that the insulator is heated by the self-cleaning property against soot attached by combustion heat, that is, the same combustion heat as the ignition plug of a gasoline engine heats the insulator. As a result, it has a function of burning HC and the like adhered to the surface by heating to keep cleanliness, and prevents soot from adhering to the positive electrode 9a. The positive electrode 9 is arranged at a position as far as possible from the cylinder liner 3c where it is difficult for soot or sulfide as exhaust particulates in the EGR gas to adhere, that is, at the center position of the cylinder liner 3c.

Specifically, the positive electrode plug 9 is, as shown in FIG. 4, the fuel injection valve 1 on the lower surface of the cylinder head 3a.
5, within a region corresponding to the combustion chamber 3e of the piston 3d, and within the virtual circle I including the intake passage opening 3f and the exhaust passage opening 3g on the lower surface of the cylinder head 3a as shown in FIG. It is provided in. More preferably,
The positive electrode plug 9 includes a center point O1 of the intake passage opening 3f and the exhaust passage opening 3 on the lower surface of the cylinder head 3a.
It is provided in a region B within an imaginary circle II including the center points O1 and O2 on the straight line passing through the center point O2 of g and the vicinity of the intermediate point O3.

A charging portion is formed by the insulating cylinder 10, the negative electrode 11, the positive electrode 12, and the high-voltage DC power supply 13,
The positive electrode 9a of the positive electrode plug 9 and the high-voltage DC power supply 13 form a dust collecting part. The positive electrodes 12 and 9a are connected to the same high-voltage DC power supply 13, so that the same voltage is applied to the charging section and the dust collecting section. Further, in order to maximize the charging function and the dust collecting function in the charging unit and the dust collecting unit, the applied voltage of the high-voltage DC power supply 13 is up to voiced discharge (spark discharge) which causes a rapid increase in power consumption and destruction of parts. A voltage that maintains a silent discharge (corona discharge) with a slightly lower voltage that does not reach is preferable. Specifically, the high voltage DC power supply 13
The applied voltage is about 3 to 7 kv (6 to 14 kv if the electrode interval is 20 mm) when the electrode interval between the negative electrode 11 and the positive electrode 12 is 10 mm.

The operation will be described below. The operating range of the engine that operates the charging device 8 is a range in which EGR (exhaust gas recirculation) is performed, and the EGR amount is variable by the control valve 7 (FIG. 1) according to the operating state of the engine. An example of a map of this EGR amount is shown in FIG. 1 and 2, a part of the exhaust gas discharged from the engine 3 to the exhaust passage 4 is returned to the intake passage 2 through the bypass passage 6 and the EGR control valve 7, and the air cleaner 1 to the intake passage 2
Is mixed with fresh air supplied to the engine and flows toward the engine 3. In the charging device 8, corona discharge occurs between the discharge electrode 11 and each positive electrode 12, and negative ions are generated from the discharge electrode 11. The negative ions move from the discharge electrode 11 to each electrode 12 along the lines of electric force generated between each positive electrode 12 and the discharge electrode 11.

Then, a mixed gas of fresh air and EGR gas (exhaust gas) flows in from the left side of the charging device 8 in the figure. EG
The R gas contains soot, sulfide, and the like as exhaust particulates (PM), and when passing between the discharge electrode 11 and each electrode 12, a collision with negative ions is generated in these electrode spaces. Upon receipt, soot and sulfide particles are negatively charged. On the other hand, the intake passage 2 has the same electric potential as the discharge electrode 11, so that the negatively charged soot and sulfide are subjected to the repulsive force of Coulomb and do not adhere to the inner surface of the intake passage 2. It flows into the cylinder liner 3c of the engine 3.

The engine 3 has a negative potential like the intake passage 2, and the negatively charged soot and sulfide in the EGR gas flowing from the intake passage 2 are negative cylinder head 3a, cylinder liner 3c, It receives Coulomb's repulsive force from the piston 3d (FIG. 2) and also the attractive force toward the positive electrode 9a. As a result, soot and sulfides collect in the upper part and near the center of the cylinder liner 3c, are taken into the combustion chamber 3e provided at the top of the piston 3d, and adhere to the surface of the cylinder liner 3c, the piston ring, and the like. To be prevented. Then, the EGR taken into the combustion chamber 3e
The gas is combusted with the fuel injected from the fuel injection valve 15 (FIG. 4) into the combustion chamber 3e.

FIG. 7 shows a second embodiment of the EGR gas charging device, in which a high-voltage DC power supply for the charging section and a high-voltage DC power supply for the dust collecting section are separately provided, and the discharge electrode 11 and each positive electrode are provided. The electrode 12 is connected to the high voltage DC power source 20, and the positive electrode 9a is
It is connected to the high voltage DC power supply 21. The control unit 22 controls the high-voltage DC power supply 20, and the control unit 23 controls the high-voltage DC power supply 21. For example, the applied voltage of the power source 20 is set to the discharge electrode 11 and the positive electrode 1.
In the case where the distance from 2 is about 10 mm, it can be adjusted within the range of about 3 to 7 kv (about 6 to 14 kv if the electrode distance is 20 mm). Moreover, the maximum value of the applied voltage of the power source 21 varies depending on the compression state by the piston 3d, and is 3 to 7 kv (maximum) which is the same as that of the power source 20 in the intake stroke, and 3 to 7 kv (maximum) in the initial stage in the compression stroke. ), Near the top dead center, it can be adjusted to a range of about 30 to 70 kv (maximum).

These control units 22 and 23 variably control the voltage applied to the high-voltage DC power supplies 20 and 21 according to the operating state of the engine. In particular, the control unit 23 is adapted to change the applied voltage of the high-voltage DC power supply 21 to an optimum voltage according to the compression state in the cylinder as described above. The voltage applied to the high voltage DC power supply 20 of the charging section does not necessarily have to be variable.

By making it possible to control the applied voltages of the high-voltage DC power supplies 20 and 21, respectively, the capacity of the charging device 8 can be adjusted to an optimum value according to the EGR amount shown in FIG. Along with this, the dust collection capability of the charging device 8 can be maximized, and the amount of wasted electricity can be minimized. When the applied voltage is not changed like the high voltage DC power supply 13 shown in FIG. 2, there are advantages that the cost of the power supply can be minimized and the cost efficiency is high.

[0020]

As described above, according to the present invention, E
Soot and sulfide as exhaust particulates in the GR gas are prevented from adhering to the cylinder liner surface of the engine, the piston ring, etc. As a result, corrosion and wear of the cylinder liner and wear of the piston ring are prevented. Furthermore, EGR
The soot and sulfide in the gas are prevented from being mixed with the oil, and the durability of the engine is improved.

[Brief description of drawings]

FIG. 1 is an E to which an EGR gas charging device according to the present invention is applied.
It is a schematic block diagram of a GR air supply engine.

FIG. 2 is a cross-sectional view showing a first embodiment of the EGR gas charging device of FIG.

FIG. 3 is an enlarged view of a main part of the positive electrode plug of FIG.

FIG. 4 is a detailed cross-sectional view near the cylinder of the engine of FIG.

5 is an explanatory view showing a mounting range of the positive electrode plug of FIG. 2 to an engine.

FIG. 6 is a diagram showing an example of a map of EGR amount.

FIG. 7 is a cross-sectional view showing a second embodiment of the EGR gas charging device of the present invention.

[Explanation of reference numerals] 1 air cleaner 2 intake passage 3 engine 4 exhaust passage 5 muffler 6 bypass passage 7 EGR control valve 8 EGR gas charging device 9 positive electrode plug 9a positive electrode 10 cylindrical body 11 discharge electrode (negative electrode) 12 positive electrode 13 , 20, 21 High-voltage DC power supply 22, 23 Control unit 15 Fuel injection valve

Claims (11)

[Claims] 1. An EGR control unit configured to recirculate a part of exhaust gas to an intake system to reduce NOx, an intake passage of the engine, and a downstream side of an exhaust gas introduction hole of the intake passage. A cylindrical body that is connected to the above and forms a part of the intake passage and is formed of an insulating member; and a first electrode that is disposed along the axial direction at the center of the cylindrical body and has a base end supported by the cylindrical body. A second electrode, which is disposed in the cylinder so as to face the first electrode in a spaced-apart relationship and has a base end supported by the cylinder, and a negative electrode which is connected to at least the base end of the first electrode and the intake passage. And a power supply means having a positive electrode connected between the second electrodes, and a charging means for applying a high-voltage DC voltage to the first and second electrodes to generate corona discharge between the two electrodes. Insulated on the cylinder head of the engine Fine particles in the negatively charged exhaust gas, which are both positively connected to the cylinder and connected to the positive electrode of the power supply means, and an engine body connected to the negative electrode of the power supply means, are charged to the positive electrode. An EGR gas charging device comprising: a dust collecting unit that sucks the dust around. 2. A first power source having a first negative electrode connected to the base end of the first electrode and the intake passage, and a second positive electrode connected to the second electrode, The EGR gas charging device according to claim 1, further comprising a second power source having a second positive electrode connected to the positive electrode and a second negative electrode connected to the engine body. 3. The EGR gas charging device according to claim 1, wherein the first power supply and the second power supply have the same set voltage. 4. A power supply means includes the first power supply and the second power supply.
The EG is provided with a transformer for varying the set voltage of the power source.
The EGR according to any one of claims 1 to 3, wherein the set voltage is made variable based on an EGR amount which is made variable by the R control means according to an operating state of the engine.
Gas charging device. 5. The power supply means comprises a transformer means for varying the power supply voltage of the second power supply according to the compression state in the cylinder. The EGR gas charging device described in 1. 6. The EGR gas charging device according to claim 1, wherein a plurality of the second electrodes are diagonally arranged with the first electrode as a center. 7. The EGR according to any one of claims 1 to 5, wherein a plurality of the second electrodes are arranged on a circumference of a predetermined radius with the first electrode as a center. Gas charging device. 8. The positive electrode is provided on the lower surface of the cylinder head around the fuel injection valve and in a region corresponding to the combustion chamber of the piston.
The EGR gas charging device according to claim 1. 9. The positive electrode is provided in a region within a first imaginary circle including an intake passage opening and an exhaust passage opening on a lower surface of a cylinder head. The EGR gas charging device according to item 1. 10. The center point of the positive electrode, centering on a portion near a midpoint between two center points on a straight line passing through the center points of the intake passage opening and the exhaust passage opening on the lower surface of the cylinder head. The EGR gas charging device according to any one of claims 1 to 7, wherein the EGR gas charging device is provided in a region within a second virtual circle that includes the. 11. The EGR gas charging device according to claim 1, wherein the positive electrode has a self-cleaning property.