JPH04121411A - Exhaust gas purifying device of diesel engine for car - Google Patents

Abstract

PURPOSE:To accomplish an exhaust gas purifying device which exhibits less exhaust pressure loss and ensures easy processing of separated soot particles by furnishing electrode part where the neg. electrode collects Diesel particulates electrostatically, and installing a high voltage power supply part which supplies high voltage to between these electrode parts. CONSTITUTION:An upstream and a downstream exhaust pipe 1a, 1b are coupled by an outer can 2, and a high voltage electrode part 5 is extended on the axis of this outer can 2 with the two ends held at insulators 3, 4, and a high voltage power supply part 6 is connected with this high voltage electrode part 5. The exhaust gas emitted by a Diesel engine is fed to the outer can 2 via an upstream exhaust pipe la and also exhausted to the outside through a downstream exhaust pipe 1b and a silencer. At this time, the high voltage power supply part 6 impresses a neg. DC high voltage to the high voltage electrode part 5, and corona discharge is generated between the high voltage electrode part 5 and outer can 2. Therefore. Diesel particulates in the exhaust gas are charged negatively and deposit on the inside circumference of the outer can 2 while drawn by the electric field between the high pressure power supply part 5 and outer can 2, and clean exhaust gas is exhausted from the downstream exhaust pipe 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust gas purification device for a diesel engine for a vehicle.

[Prior Art] Conventionally, there has been a serious problem that diesel particulates contained in the exhaust gas from diesel engines for vehicles such as buses and trucks pollute the environment. Devices that purify exhaust gas by adsorbing particles are known.

[Problems to be Solved by the Invention] However, the above-described method of adsorbing soot and dust particles using a ceramic filter or the like has the disadvantage that the exhaust pressure loss is large and the engine efficiency is reduced accordingly.

In particular, when the amount of soot particles adsorbed increases, the exhaust pressure loss increases at an accelerated rate, and the amount of air taken into the diesel engine decreases, leading to a significant drop in output and deterioration of combustion characteristics.

The present invention has been made in view of the above-mentioned problems, and an object to be solved is to provide an exhaust gas purification device for a diesel engine that has low exhaust pressure loss and can easily process separated soot particles. There is.

[Means for Solving the Problems] The exhaust gas purification device for a vehicle diesel engine of the present invention has the following features:
A pair of electrode parts are provided in the exhaust path of a vehicle diesel engine with a predetermined gap between them, and a negative electrode electrostatically collects diesel particulates.A high voltage is supplied between the electrode parts to collect diesel particulates in the gap part. It is characterized by comprising a high voltage power supply section for collecting curate.

[Function and Effects of the Invention] The diesel engine exhaust gas purification device of the present invention applies the principle of electrostatic precipitation to separate diesel particulates contained in the exhaust gas of a diesel engine from the exhaust gas.

That is, diesel particulates discharged from a diesel engine are strongly negatively charged as a result of the combustion reaction and air flow inside the cylinder.

Therefore, while passing through the gap between the pair of electrode sections in the exhaust path, diesel particulates are collected at the positive electrode of the electrode section due to the electric field formed by the electrode sections in the gap.

Furthermore, if a corona discharge is generated by the applied voltage, the diesel particulates will become even more negatively charged, and even more
Collected on the positive electrode.

Therefore, according to the device of the present invention, an increase in exhaust pressure loss of a diesel engine, a corresponding decrease in engine output, and deterioration of in-cylinder combustion are hardly caused.
It becomes possible to purify exhaust gas. Furthermore, the device itself can be made much lighter and smaller than a ceramic filter or the like.

[Example] (Example 1) An embodiment of the present invention is shown in FIG.

This device includes an outer can part 2 that fits into an upstream exhaust pipe 1a and a downstream exhaust pipe 1b of a vehicle diesel engine (not shown) to connect the two exhaust pipes 1a and 1b; The insulator 3.4 is fitted into the central hole 11 opened at both ends:
A stainless steel high voltage electrode part 5 whose both ends are held by insulators 3.4 and which extends on the axis of the outer can part 2;
A high voltage power supply section 6 having an output terminal 61 connected to
It consists of

The outer can part 2 is made of stainless steel and has a circular pressure shape, and has a main cylinder part 23 that is open at both ends and has an inlet cylinder part 21 and an outlet cylinder part 22 protruding from the outer peripheral surface, and is fitted into both ends of the main cylinder part 23. Main cylinder part 23
It consists of a lid part 24 that removably seals the openings at both ends.

The inlet cylindrical part 21 and the outlet cylindrical part 22 are respectively protruded in the same direction in close proximity to each end of the outer can part 2, and are fitted into the upstream exhaust pipe 1a and the downstream exhaust pipe 1b, respectively, to connect both ends. Exhaust pipes 1a and 1b are connected to allow exhaust gas to flow. A cylindrical wall portion 25 is provided at the center of the lid portion 24 to protrude outward in the axial direction.

The insulator 3.4 is made of alumina porcelain, and has a cylindrical fitting part 31.41 that is removably fitted into the cylindrical wall part 25 of the lid part 24, and is integrally formed with the fitting part 31.41 to form a main cylinder part. Inner flame part 32.42 extending along the axis into 23
It consists of A plurality of corrugated ribs 33.43 for preventing creeping discharge are provided on the outer peripheral surface of the inner flame portion 32.42.

A rod-shaped high-voltage electrode part 5 is inserted and fixed into a hole 35.45 provided along the axis in the center of the insulator 3.4, and one end of the high-voltage electrode part 5 passes through the insulator 3. The other end is embedded in the insulator 4.

High voltage power supply section 61. A negative DC high voltage is applied to the high voltage electrode part 5 connected to the output terminal 61, and corona discharge is generated between the outer can part 2 and the high voltage electrode part 5, which are grounded through the vehicle body (not shown). let Since the circuit configuration of the high voltage power supply section 6 itself is well known, its explanation will be omitted.

The operation of this device will be explained below.

Exhaust gas emitted from the diesel engine is sent into the outer can section 2 via the upstream exhaust pipe 1a, and is then discharged to the outside via the downstream exhaust pipe 1b and a muffler (not shown).

The high-voltage power supply section 6 applies a negative DC high voltage to the high-voltage electrode section 5 to generate corona discharge between the high-voltage electrode section 5 and the outer can section 2 . Diesel particulates in the exhaust gas are negatively charged by this corona discharge, are attracted by the electric field between the high voltage electrode part 5 and the outer can part 2, and are deposited on the inner circumferential surface of the outer can part 2. Clean exhaust gas is discharged from pipe 1b.

Note that diesel particulates accumulated inside the outer can section 2 are cleaned regularly. For cleaning, first pull the outer can part 2 upward in FIG.
8 and the downstream exhaust pipe 1b, and then both lids 24
What is necessary is to remove it from the main cylinder portion 23 and the insulator 3.4 and remove the diesel particulates inside.

In this way, the dust particle layer can be easily removed.

Next, FIG. 2 shows the results of a test conducted using this device.

However, the diameter of the inner peripheral surface of the outer can part 2 is 55 mm, the diameter of the high voltage electrode part 5 is Q, 5 mm, and the effective axial length of the high voltage electrode part 5 is 1.
00cm. As can be seen from FIG. 2, the contamination rate decreases rapidly as the DC voltage increases. Note that the contamination rate here is the degree to which the filter paper for measuring exhaust smoke concentration is contaminated by exhaust gas as defined in JIS D 1101, and is 100-
1.15X emission tFJv1 It is expressed as a degree rate (%).

Next, Figure 5 shows the pollution rate at the time of starting the diesel engine.

It can be seen from FIG. 5 that the exhaust gas contamination rate at startup is significantly improved.

Next, FIGS. 6 and 7 show the contamination rates when the exhaust gas purification device of this embodiment is installed at the outlet of the diesel engine (upstream of the exhaust pipe) and when it is installed at the exhaust pipe outlet.

It can be seen that when it is provided upstream of the exhaust pipe (FIG. 6), the contamination rate (the case where the exhaust gas purification device of this example is not provided is 1) is significantly reduced.

This is because the diesel particulates immediately after leaving the diesel engine are strongly negatively charged due to the combustion reaction inside the cylinder, and the ionization rate is high due to the high temperature, which improves the collection efficiency. It is thought that.

(Modification) In a modification of this embodiment, the high voltage power supply unit 6 is
A voltage equal to or lower than the corona discharge voltage is applied to the high voltage electrode section 5.

As a result, no corona discharge is generated between the high voltage electrode section 5 and the outer can section 2. However, the diesel particulates discharged from the diesel engine are strongly negatively charged as a result of the flame reaction inside the cylinder (not shown), so between the high voltage electrode part 5 and the outer can part 2, It is electrostatically accelerated toward the outer can part 2 and collected by the outer can part 2.

(Example 2) Another embodiment will be explained with reference to FIGS. 3 and 4.

This device includes an outer can part 7 that fits into an upstream exhaust pipe 1C and a downstream exhaust pipe 1d of a vehicle diesel engine (not shown) to connect both exhaust pipes]C11d, and an inner can part 7 of the outer can part 7. It consists of an insulator 8.81 fixed to the side surface, a high-voltage electrode part 9 supported by the insulator 8.81, and a high-voltage power supply part 6 that supplies power to the high-voltage electrode part 9 through a connection terminal 60.

The outer can part 7 is made of stainless steel and has a rectangular box shape, and has a lead part 73 with an opening at the upper end where an inlet local part 71 and an outlet cylinder part 72 are provided on the side wall, and a lead part 73 that removably fits into the opening of the lead part 73. Part 73
and a lid portion 74 that seals the internal space of the container. Inlet cylinder part 7
1 and the outlet cylinder part 72 are removably fitted into the upstream exhaust pipe 1C and the downstream exhaust pipe 1d, respectively, so that both the exhaust pipes 1c,
1d are connected so that exhaust gas can flow therethrough.

The insulators 8 and 81 support the high voltage electrode part 9 inside the outer can part 7 so as to be electrically insulated from the outer can part 7. That is, each of the two pairs of insulators 8 is connected to one stainless steel rod 91.
．． The insulator 81 supports a stainless steel rod 93 extending at right angles to the stainless steel rods 91 and 92. The stainless steel rod 93 penetrates the insulator 81,
The connection terminal 60 is connected to the high voltage power supply section 6 via the conductor cylinder section 63. Further, the stainless steel rod 93 is welded to the stainless steel rod 9L 92, and the stainless steel rods 91, 92, and 93 are further welded to the stainless wire mesh 94. These stainless steel rods 91, 92, 93 and the stainless wire mesh 94 are arranged in parallel to the lid part 74, and a negative DC high voltage is applied to the high voltage electrode part 9 to cause corona discharge. Diesel particulate layer 10 inside
Deposit 0.

In this device as well, to clean the diesel particulate layer 100, pull the outer can part 7 to the right in FIG. Then, the lid part 74 is opened and the diesel particulate layer 100 inside the assembled part 73 is removed.

Furthermore, since the device of this embodiment is formed in the shape of a shallow rectangular box, it is easy to attach to the bottom of the vehicle body and easy to clean.

(Example 3) Another embodiment will be explained with reference to FIG.

This device is provided with two units 200 and 201 having substantially the same shape as each other in an upstream exhaust pipe [e] and a downstream exhaust pipe 1f of a vehicle diesel engine (not shown).

Units 200 and 201 have the same functions as those of the first embodiment, and each unit includes an outer can part 2, an insulator 3.4 fixed to the inner surface of the outer can part 2, and an insulator 3.4. The high-voltage electrode section 5 is connected to an output terminal of a DC high-voltage power supply section 6.

The inlet cylinder part 21a of the unit 200 fits into the upstream exhaust pipe (not shown) of the diesel engine, the outlet cylinder part 22a of the unit 200 fits into the inlet cylinder part 21b of the unit 201, and the outlet cylinder part 22a of the unit 200 fits into the inlet cylinder part 21b of the unit 201. The portion 22a is connected to a downstream exhaust pipe (not shown) of the diesel engine.

Note that the inner diameter of the outer can part 2 of the unit 200 is the same as that of the unit 200.
The inner diameter of the outer can part 2 is set larger than the inner diameter of the outer can part 2 of the unit 201. Therefore, even if the same voltage is applied to both high voltage electrode parts 5, corona discharge does not occur inside the unit 200, and corona discharge only occurs inside the unit 201. occurs.

In this way, the diesel particulates that are negatively charged due to the flame reaction inside the cylinder (not shown) are first collected in the unit 200, and then the remaining diesel particulates are collected in the unit 201 to become negatively charged due to the corona discharge. It is charged and collected.

Note that in this embodiment, it is of course possible to integrate the units 200 and 201.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
3 is a characteristic diagram showing the relationship between contamination rate and applied voltage; FIG. 3 shows a second embodiment of the present invention; and FIG. FIG. 4 is a cross-sectional view of the device of the second embodiment. Figure 5 is a diagram showing the pollution rate reduction effect at the time of startup; Figures 6 and 7 are diagrams showing the difference in pollution rate between the engine (diesel engine) outlet and the exhaust pipe outlet; The figure is a block diagram showing a third embodiment of the present invention. 1a... Upstream exhaust pipe (exhaust route) 1b... Downstream exhaust pipe (exhaust route 2... Outer can part (electrode part) 3.4... Insulator 5... High voltage electrode part ( Electrode part) 6...High voltage power supply part Patent applicant Nagao Kogyo Co., Ltd.

Claims (7)

[Claims] (1) A pair of electrode parts, which are provided in the exhaust path of a vehicle diesel engine with a predetermined gap between them, and whose negative electrode electrostatically collects diesel particulate; An exhaust gas purification device for a diesel engine for a vehicle, comprising: a high-voltage power supply section that generates an electric field for collecting diesel particulates; (2) The exhaust gas purification device for a diesel engine for a vehicle according to claim 1, wherein the high voltage power supply section applies a voltage equal to or lower than a corona discharge voltage to the electrode section. (3) The exhaust gas purification device for a diesel engine for a vehicle according to claim 1, wherein the high voltage power supply section applies a voltage higher than a corona discharge voltage to the electrode section. (4) The above pair of electrode parts includes a metal outer can part that is arranged to allow exhaust gas to pass through and also serves as a ground electrode, and a high voltage that is maintained within the outer can part while being electrically insulated from the outer can part. The exhaust gas purification device for a vehicle diesel engine according to claim 1, comprising an electrode portion. (5) The exhaust gas purification device for a diesel engine for a vehicle according to claim 2, further comprising a pair of second electrode portions for corona discharge disposed downstream of the electrode portion. (6) The exhaust gas purification device for a vehicle diesel engine according to claim 5, wherein the outer can portion is detachably attached to an exhaust pipe of the vehicle diesel engine. (7) The exhaust gas purification device for a vehicle diesel engine according to claim 5, which is disposed at an upstream portion of the exhaust pipe.