JPH0227107A - Exhaust-gas soot filter - Google Patents

Abstract

PURPOSE: To clean a ceramic member by dispersing metal particles in the ceramic member, inserting a conductor into an inflow passageway and arranging the same with an insulation space from the ceramic member. CONSTITUTION: Metal particles are finely dispersed in a ceramic member 1 that constructs a passageway of a filter. A conductor 5 is inserted into an inflow passageway 2 and is arranged with an insulation space by a spacer 6. A discharge voltage is applied between the ceramic member 1 and the conductor 5. When soot in exhaust gas of a diesel engine accumulates to form deposition 9, an arc is generated to combust soot. As a consequence, the ceramic member 1 can be automatically scavenged.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention consists of a porous ceramic member having an inlet passage and an outlet passage open on one side. It relates in particular to exhaust gas soot filters for motor vehicles with diesel engines.

Conventional technology Exhaust gas soot filter suitable for diesel cars.

It is desirable that the engine operate without trouble over its entire useful life. This assumes that 9 parts of soot are automatically removed. Since diesel engines use a lot of excess air, it is conceivable that the carbon produced as soot is combusted into carbon dioxide by the oxygen contained in the exhaust gas. Due to the strong cooling effect of the exhaust gases, the problem arises that combustion can only be maintained by energy supply. According to experiments using electrical resistance heating, in order to burn the soot contained in the exhaust gas of a diesel engine, it is necessary to move within the output range of a small car and to burn the soot contained in the exhaust gas of a diesel engine.
Power is required which can be 0 kW. The generation of ohmic heat by electrical heating is not a viable solution for the above applications.

OBJECTS OF THE INVENTION The object of the invention is to provide an exhaust gas soot filter which removes soot particles with low energy requirements and without interrupting the use of the filter.

Structure of the Invention In order to solve this problem, the present invention has the following features. That is, the ceramic member has finely dispersed metal particles and is therefore electrically conductive, and conductors are inserted into the inflow passage, and these conductors are insulated from the ceramic member by non-conductive spacers. A discharge voltage can be applied between spaced apart conductors between the ceramic member and the inflow passage.

The invention employs a method of soot combustion in an arc, whereby according to the invention the arc is generated in the inlet channel of the exhaust gas soot filter. The exhaust gas soot filter according to the invention then operates as follows. The exhaust gas to be purified thus enters the inlet channel on the inlet side, passes through the porous wall of the ceramic element into the outlet channel and leaves the filter on the outlet side of the outlet channel. The soot contained in the exhaust gas is separated on the surface of the inlet passage and is built up here over time.

If the soot builds up in sufficient quantities at any location, spark communication will occur between the soot and the conductor located within the inflow passage under the applied discharge voltage.

This is because soot is a conductor. Soot burns locally. If more time passes, an arc occurs, and the soot is converted into carbon dioxide by the oxygen contained in the exhaust gas. The release of the separated soot in the outlet passage is thus effected by a continuous and localized ignition and combustion process. Surprisingly, the build-up in the inlet passage can be limited to maintain permeability that does not impair the efficiency of the engine, regardless of the period of operation.

The metallization of ceramic components can be carried out in one variety of ways. It is within the scope of the present invention to form a ceramic member with a substantially uniform distribution of metal particles. However, it is advantageous if the fine dispersion of metal particles has the following characteristics: That is, the metal particles are concentrated on the inner surface of the inflow channel. The water passage cross-sectional area is within normal ranges. habo9
A square inlet channel with a cross-sectional area mi was found suitable. Suitable conductors are metal wires or rod-shaped electrodes placed in the center of the inflow channel.

An advantageous configuration of the invention has the following characteristics.

That is, the conductors arranged in the inflow passage are grouped together and electrically connected to form electrode blocks, and in this case, a plurality of electrode blocks are attached to the ceramic member, and these Discharge voltages can be applied to the electrode blocks independently of each other. Such a division makes it possible to partially clean the exhaust gas soot filter.

This is particularly advantageous for the cold operating phase of the engine. Furthermore, according to the invention it is advantageous to arrange a control device formed by nine makeshift circuits, a measuring voltage source and a disconnection, the interrogation circuit controlling the electrode blocks in sequence and the measuring voltage source can be connected and a short-circuit measurement can be carried out, with a disconnection circuit disconnecting the electrode block containing the short-circuit and applying a discharge voltage to the electrode block without a short-circuit. In this advantageous embodiment of the invention, the blocks are connected one after the other to a measuring voltage source during one engine start or for a short period thereafter, the current measurement determining which blocks are still short-circuited due to penetrating moisture. To detect. These blocks are first excluded from further operation. Obviously, the make-up circuit can be operated repeatedly with a one-timer, and the electrode block containing the short circuit is tested again for short circuits after one period of time. As soon as the electrode blocks are no longer short-circuited because the condensed water has evaporated due to the increased filter humidity, the blocks that are now operating correctly are likewise connected to the discharge voltage.

The exhaust gas soot filter according to the invention is advantageous in that it operates without maintenance during the entire useful life of an engine. In this case, neither the permeability of the filter is disturbed nor the degree of separation is changed. Automatic cleaning of the porous ceramic component is carried out in accordance with the respective amount of soot produced. Since the energy requirements required for eliminating the separated soot are low, this exhaust gas soot filter is also suitable for small-power diesel engines.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

The illustrated exhaust gas soot filter, which can be used in particular for motor vehicles with diesel engines, has a porous ceramic member l, which ceramic member has a porous ceramic member l.

It is formed to have an inflow passage 2 and an outflow passage 3 that are open on one side. As can be seen from a comparative consideration of FIGS. 1 and 2, the water passage 2.3 has a square cross section.

The cross-sectional area is approximately 9 mJ.

The inflow and outflow channels 2.3 are arranged in a honeycomb manner. Ceramic component 1 thus has a large filter area.

The ceramic member 1 has finely dispersed metal particles.
In this embodiment and according to an advantageous configuration of the invention, these metal particles are concentrated on the inner surface 4 of the inlet channel 2. The ceramic member 1 has electrical conductivity due to the metal particles.

The ceramic member l thus metallized is electrically connected to the vehicle frame. A conductor 5 is inserted into the inflow passage z. These conductors are connected to the non-conductive spacer 6
The ceramic member 1 is arranged at an insulating distance a from the ceramic member 1. A discharge voltage can be applied between the ceramic member and the conductor 50 arranged in the inlet passageway 2 .

FIG. 1 shows the operation of the exhaust gas soot filter shown in FIG. The exhaust gas enters the inlet channel 2 from the inlet side 7 in the direction of the arrows 9, flows through the porous wall of the ceramic member 1 into the outlet channel 3 and leaves the filter at the outlet side 8 of the outlet channel 3. The soot contained in exhaust gas is
They are separated at the inner surface 4 of the inflow passage 2 and form a dense layer 9. As soon as the soot accumulates high enough in one or more locations 10, a yoriarc occurs under the action of the discharge voltage, and the soot, energized by the arc, is locally combusted by the oxygen contained in the exhaust gas. to form carbon dioxide.

The conductors 5 arranged in the inflow passage 2 are grouped together and electrically connected to form an electrode block 11 (FIG. 3). Connect 100 conductors and make 1
Advantageously, there are two electrode blocks. A plurality of electrode blocks are attached to the ceramic component, to which a discharge voltage can be applied independently of one another via connection contacts 12. Furthermore, a control device (not shown) is provided, which has an intermediary circuit, a measuring voltage source and a cut-off circuit. The makeshift circuit connects the electrode block to the measurement voltage source and performs short-circuit measurements during one engine start and for a short period thereafter. In this way it is detected which blocks are still shorted due to the intruding moisture. The cutoff circuit is designed to first exclude the shorted block from further operation and apply a discharge voltage to the electrode blocks that do not contain the shorted circuit. The makeshift circuit is 1
The timer is activated repeatedly and a short-circuit measurement is carried out again after a period of time in the block containing the short-circuit. As the filter temperature increased and the condensed water evaporated,
As soon as there is no longer a short circuit in the electrode block, the operational block is likewise subjected to a discharge voltage.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing a part of the exhaust gas soot filter according to the present invention, Fig. 2 is an enlarged cross-sectional view of the inflow passage from Fig. 1, and Fig. 3 is a view of the electrode block. FIG. 3 is a diagram showing the configuration.

Claims (4)

[Claims] (1) In an exhaust gas soot filter especially for automobiles with diesel engines, which consists of a porous ceramic member having an inflow passage and an outflow passage open on one side, the ceramic member (1) has finely dispersed metal particles. conductors (5) are inserted into the inflow channel (2), and these conductors are kept at an insulating distance from the ceramic member (1) by means of non-conductive spacers (6). (a) and a conductor (5) disposed within the ceramic member (1) and the inflow passage (2).
) Exhaust gas soot filter, characterized in that a discharge voltage can be applied between the exhaust gas and soot filters. 2. Exhaust gas soot filter according to claim 1, wherein the metal particles are concentrated on the inner surface (4) of the inlet passageway (2). (3) The conductors (5) arranged in the inflow passage (2) are grouped together and electrically connected to form an electrode block (11), in which case the ceramic member ( 3. Exhaust gas soot filter according to claim 1, wherein a plurality of electrode blocks (11) are attached to the exhaust gas soot filter (1), to which a discharge voltage can be applied independently of one another. (4) A control device having an interrogation circuit, a measuring voltage source and a cut-off circuit is provided, the interrogating circuit controlling the electrode block (11) in sequence and the measuring voltage source being connectable. 4. The exhaust gas soot according to claim 3, wherein a short-circuit measurement can be carried out, in which the interrupting circuit interrupts the electrode block (11) containing the short-circuit and applies a discharge voltage to the electrode block (11) without a short-circuit. filter.