JPH07310531A - Diesel particulate filter - Google Patents

Abstract

(57) [Summary] [Purpose] To collect and incinerate pollutants in various exhaust gases generated by the operating conditions of diesel engines with an appropriate filter. [Structure] An inner filter 23, which is a coarse metal filter, is arranged at the center of the filter case 1, and an opening / closing valve 28 having an offset spindle is attached to the inlet of the filter case 1 to open according to the exhaust pressure. A fine medium filter 22 in which ceramic fibers and a metal heater are combined is arranged immediately outside the filter 23, and a pressure regulating valve 25 that is biased in the closing direction by a spring 27 and opened by an increase in exhaust pressure is provided downstream. Install. An outer fine outer filter 21 made of the same material as that of the middle filter 22 is arranged at the outermost periphery to form a triple structure filter, and the pressure regulating valve 25 and the on-off valve 28 are operated according to the exhaust pressure according to the engine operating conditions. To collect the blue-white smoke and particulates contained in the exhaust gas,
The conductive filter itself is energized to incinerate the deposit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel particulate filter that collects and incinerates particulates contained in exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art Since a diesel engine injects fuel into high-pressure high-temperature air and mixes it, the fuel is often not completely mixed and carbonized at the time of ignition, and is often discharged as fine particles in exhaust gas. Such particulate carbon and hydrocarbon compounds are called particulates and are one of the causes of urban pollution that pollutes the atmosphere.

For this reason, a filter made of a porous material that collects particulates is attached to the exhaust passage of a diesel engine to clean the exhaust gas.

[0004]

By the way, among diesel engines, particularly those in which a turbocharger is attached to the exhaust system to increase the supercharging pressure by recovering exhaust energy, particulate matter in the exhaust gas during the sudden start, It contains a lot of smoke and emits white and white smoke when the engine is started. Furthermore, when a vehicle with a large load is climbing uphill, the engine is operated in a state of being close to the full load, so a large amount of particulates will be discharged.

As described above, the state of smoke and particulates discharged varies depending on the operating conditions of the engine, and it is difficult to purify the exhaust gas corresponding to these states.

Further, it is difficult to remove the particulates collected and deposited on the filter, and even if the deposit is ignited and burned, it partially burns and the filter element may melt due to excessive temperature rise. .

The present invention is intended to solve such a conventional problem, and its object is to efficiently filter the smoke and particulates in the exhaust gas generated by the operating conditions of the engine. The purpose of the present invention is to provide a diesel particulate filter that is intended to be cleaned and to be screened for deposit incineration without damaging the filter.

[0008]

In order to achieve the above object, according to the present invention, exhaust gas of a diesel engine is guided to a filter in which a porous filter and a conductive material are combined to collect particulates. , In a diesel particulate filter that incinerates the deposit collected by passing an electric current through the filter, the inlet is arranged in the substantially central portion of the filter and the inlet portion is made of a metal tube, and on the extension thereof,
A first filter having a coarse filter on the downstream side and provided with an opening / closing valve that opens in response to a rise in exhaust pressure, and a first filter provided outside the first filter, in response to fluctuations in the pressure of a gas flow passing therethrough. A pressure regulating valve that opens is provided at the outlet, and its mesh is the first
Provided is a diesel particulate filter in which a second filter having a closer mesh than the filter and a fine third filter arranged outside the second filter are arranged in parallel to the exhaust gas flow. To be done.

According to the present invention, the on-off valve is supported by an eccentric support shaft, the pressure regulating valve is biased in the closing direction by a spring, and when the second and third filters are clogged by particulates, A diesel particulate filter that opens by increasing the exhaust pressure is provided, further, the first filter is made of a conductive metal or ceramic porous material having a mesh, and the second and third filters are laminated with ceramic fibers. A filter in which a metal heater partially woven from it is combined is used.Each filter is provided with a diesel particulate that can be regenerated by stacking it with a conductive wire mesh material and incinerating the particulates. Depending on the operating conditions of the engine, the particulates are incinerated and regenerated. That.

[0010]

When an opening / closing valve that opens due to an increase in exhaust pressure is provided at the inlet of the coarse first filter arranged in the central portion of the filter, and the gas flow passing therethrough increases immediately outside the first filter. A triple filter is provided by arranging a second filter equipped with a pressure regulating valve, which is opened according to the rise in generated exhaust gas pressure, at the outlet, and further providing an extremely fine third filter on the outside thereof. When the amount of exhaust gas is relatively small due to engine start or sudden start, the on-off valve and pressure regulating valve do not open, and the particulates generated under those conditions are bluish white smoke due to the fine mesh third filter. It is collected, but when the third filter is clogged, or
When the exhaust gas flow increases and the engine load is high, the pressure regulating valve is opened and filtration by the second filter is also performed. When the second and third filters are clogged and the exhaust gas pressure rises, the first filter opens, and the valve opening signal energizes the second and third filters to incinerate the particulates. When the incineration is completed, the opening / closing valve of the first filter is closed and electricity is supplied to regenerate the filter.

Since each of the three types of filters has conductivity, the filters themselves uniformly generate heat when the heating power is applied, and the deposits are incinerated.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an embodiment of a diesel particulate filter according to the present invention.

Reference numeral 1 in the figure is a filter case,
It is formed into a cylindrical shape whose upstream and downstream directions are narrowed,
On the upstream side, a flange 11 connected to the exhaust pipe of the engine
However, a mounting plate 12 for connecting a tail pipe is provided on the downstream side, and the filter block 2 is housed in the central case 10 via a layer of a heat insulating material 13 inscribed in the case.

The filter block 2 is a concentric cylinder 2 which serves as a bypass pipe opening in the central portion in the upstream direction.
0, and an outer filter 21 serving as a cylindrical third filter and a middle filter 22 serving as a second filter are doubly and concentrically arranged on the outer periphery of the cylinder 20, both of which are, for example, long. A filter element in which a filter material in which fiber ceramics are laminated and a metal mesh-shaped heater are superposed and engaged with each other is used. The outer filter 21 is a fine filter, and the middle filter 22 is a coarser mesh filter. It is formed by.

Then, the outer filter 21 and the middle filter 22
And the exhaust gas flowing through the middle filter is closed by the pressure regulating valve 25, and the end face 24 is outside.
The end face member 24 and the cylinder 20 are in contact with the end of the middle filter.
As shown in the drawing, a funnel-shaped pressure regulating valve 25 whose diameter is gradually reduced in the downstream direction is attached so as to slide on the cylinder. One end of the pressure regulating valve 25 is located downstream of the cylinder 20. Spring 27 held by end stopper 26
Is always pressed in the upstream direction by the medium filter 2
The flow path downstream from 2 is closed. Therefore, the exhaust flow that flows between the outer filter 21 and the middle filter 22 is filtered on the outer filter 21 side, passes through the outer side, and passes through the mounting plate 1.
The gas that has flowed out through the second filter 2 but is filtered by the middle filter 22 has a large exhaust flow rate or the outer filter 21.
If the valve is clogged, the pressure rises and the pressure regulating valve 25
It is configured to open and to flow in the downstream direction.

Next, inside the cylinder 20, a coarse inner filter 23, which serves as a first filter having a ceramic coating on the outside of a bottomed cylindrical porous metal filter, is attached, while on the other hand, upstream of the cylinder 20. An on-off valve 28 that opens and closes according to the pressure of the exhaust gas is provided at the inlet, and the on-off valve 28 is operated by an actuator 31 and the spindle of the on-off valve 28 is offset.
When particulates are deposited on the second and third filters and the exhaust pressure from the engine becomes high, torque is applied to the shaft of the opening / closing valve 28 to open the valve. Reference numeral 32 is a clogging sensor, which is provided on the inner surface of the inner filter 23, detects a change in the electric resistance value due to the accumulation of particulates, and sends the clogging state to a controller described later, and 33 is the exhaust pressure. It is attached to the upstream inner surface of the filter case 1 by a sensor, detects the pressure of the exhaust gas and sends it to the controller. The open / close valve is opened by the signal from the clogging sensor or the open signal from the open / close valve.

Reference numeral 30 is a battery, which is a power source for supplying electric power to the controller and the clogged filter, 34 and 35 are energizing terminals for the inner filter 23, and 36 and 37 are heating the middle filter 23 and the outer filter 21, respectively. It is an energizing terminal for supplying electric power for use.

The controller 3 is composed of a microcomputer, and is provided with a central control unit for performing arithmetic processing, various memories for storing arithmetic processing procedures and control procedures, an input port, an output port, and the like. When a signal from a clogging sensor or the like is input, a predetermined calculation is performed, and the actuator 31 is operated based on the stored control procedure.
Is issued, and a command to supply power to a predetermined energizing terminal is issued.

Next, the operation of this embodiment thus constructed will be described. Although blue-white smoke is exhausted from the exhaust pipe when the engine is started, the opening / closing valve 28 of the cylinder 20 is small because the engine load is small, the rotation speed does not reach the rated rotation, and the exhaust pressure is low.
And the pressure regulating valve 25 is not opened, so that the exhaust flow reaches the ultrafine outer filter 21 and is filtered, and the fine particles of blue and white smoke are collected and purified gas is discharged downstream through the mounting plate 12. It

Smoke with a large amount of particulates is discharged when the engine suddenly starts. This is because when the accelerator pedal is depressed, the fuel flow rate is immediately increased correspondingly, but the air flow is the resistance of the air cleaner and the operation of the turbocharger. Does not follow, the amount of air is insufficient and smoke increases. Since the exhaust gas is not so large, the pressure is low, and the outer filter 21 collects the exhaust gas as in the case of the start.

When the outer filter 21 is clogged with deposits due to collection, the exhaust pressure rises, the pressure regulating valve 25 is opened, the exhaust flow is passed through the middle filter 22, and it is purified without excessive resistance. Gas will be released. Even when the outer filter 21 is not clogged, if the engine load is large, the exhaust temperature increases, the exhaust flow rate becomes large, or the exhaust pressure due to large pulsation increases due to rapid acceleration, the pressure regulating valve 25 is opened and the fine valve is opened. Since the exhaust flow flows through the middle filter 22, the resistance of the flow path does not increase so much.

Then, when the engine load further increases, such as when climbing a slope, the exhaust pressure rises, so that the on-off valve 28 upstream of the cylinder 20 is opened by applying torque to the unbalanced spindle.
Since the exhaust gas flows through the coarse inner filter 23, the exhaust gas pressure does not rise excessively and does not adversely affect the engine.

Further, when the exhaust pressure rises due to the second and third filter clogging during normal operation of the engine, the opening / closing valve 28 opens, and the signal from the opening / closing valve 28 causes the actuator 31 to open / close the valve 28.
To open. Further, when the clogging sensor 32 provided in the filters 21 and 22 detects clogging, the energizing terminals 37, 3
The heating power is supplied to 6 and the inner filters 21 and 22 are screened. Further, in the state where the energization is completed, the filter 23 is supplied with power to the energizing terminal 35 to perform the screening. When the exhaust pressure sensor 33 detects an increase in exhaust pressure due to clogging of the outermost outer filter 21, the energization terminal 37 is energized and the screening is performed.

As described above, when each filter is energized, the metal wire mesh heater is provided, or the filter itself is metallic or conductive ceramics, so that the heat generated by energization is evenly distributed to each part of the filter and the temperature is As a result, the deposits will not burn on average and partial abnormal combustion will not occur, so that accidents such as melting damage of the filter can be prevented.

As described above, the state of the exhaust gas particulates and the exhaust pressure differ depending on the operating conditions, such as when the engine is started, when the engine is suddenly started or when the engine is fully loaded, but the filter case has extra fine, fine and coarse particles. Since three types of filters are installed concentrically, an on-off valve is installed upstream of the coarse inner filter, and a pressure regulating valve is installed downstream of the fine inner filter to open the valves when exhaust pressure rises. The various pollutants contained in can be appropriately removed, and even when incinerated, screening can be performed without damage because the filter itself is made conductive.

[0026]

As described above, according to the present invention, an opening valve that opens due to an increase in exhaust pressure is attached to the inlet of the coarse inner filter arranged in the central portion of the filter, and the fine valve arranged immediately outside the inner filter is installed. The inner filter has a pressure regulating valve that opens according to the increase of exhaust pressure downstream of it, and a fine outer filter is placed outside it to form a triple structure. The on-off valve and pressure regulating valve are activated by the amount and its exhaust pressure, and the effect that the white and white smoke and particulates contained in the exhaust gas are collected by an appropriate filter, and the filter itself has conductivity. Therefore, there is an advantage that the filter is prevented from being damaged because the heat is uniformly generated when the electric power for heating is applied and abnormal combustion of the deposit does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a diesel particulate filter according to the present invention.

[Explanation of symbols]

 1 ... Filter case 10 ... Central case 11 ... Flange 12 ... Mounting plate 2 ... Filter block 20 ... Cylindrical 21 ... Outer filter 22 ... Medium filter 23 ... Inner filter 25 ... Pressure regulation valve 27 ... Spring 28 ... Open / close valve 3 ... Controller 30 ... Battery 31 ... Actuator 32 ... Clogging sensor 33 ... Exhaust pressure sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F01N 3/02 B 9/00 ZAB Z

Claims (6)

[Claims] 1. A diesel particulate matter in which exhaust gas of a diesel engine is guided to a filter made of a combination of a porous material and a conductive material to collect particulates, and an electric current is passed through a wire mesh conductive material to incinerate the collected deposits. In the filter, a pipe having an opening / closing valve arranged at an approximately central portion of the filter, a first filter having a coarse filter mesh connected to a downstream thereof and having conductivity, and an outer side of the first filter A second filter provided with a pressure regulating valve having an intermediate filter roughness and having an opening according to the flow, and a fine third filter arranged outside the second filter are arranged in parallel. Diesel particulate filter characterized by. 2. The diesel particulate filter according to claim 1, wherein in the filter disposed in the central portion, the opening / closing valve is automatically opened by a predetermined exhaust pressure. 3. An on-off valve provided in a filter tube arranged at the center of the filter tube is supported by an eccentric support shaft, and is opened by a rotational torque of exhaust pressure applied to an unbalanced portion. The diesel particulate filter according to claim 1, further comprising an actuator that holds the diesel particulate filter for a predetermined time. 4. The elastic force of a spring is applied in a closing direction so that the pressure regulating valve provided in the second filter opens in response to a predetermined exhaust pressure. Diesel particulate filter described. 5. The first filter has a coarse mesh and is a conductive metal filter or ceramic filter, and the second and third filters partially use ceramic or metal fibers. The diesel particulate filter according to claim 1, wherein a filter in which a woven filter and a metal mesh heater are combined is used. 6. A second filter and a third filter are energized for a predetermined time by an opening signal of the on-off valve provided in the central filter tube, and after a predetermined time, the on-off valve is closed and a first filter is operated for a predetermined time. The diesel particulate filter according to claim 1, further comprising a control device that energizes for a period of time.