JPS6233938Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a particulate matter purification device that collects particulate matter contained in exhaust gas in a heat-resistant filter and purifies it by re-burning it under certain conditions.

This particulate is an aggregate of carbide, which is mainly soot, and fine hydrocarbon particles, and has electrical conductivity. When exhaust gas recirculation (EGR) is performed to reduce NOx in exhaust gas, the particulate content tends to increase, especially during high-load operation. In order to prevent such particulate matter from being released into the atmosphere, an apparatus is known in which a heat-resistant filter is interposed in the exhaust gas passage and the particulate matter is collected by the filter.

By the way, if the particulate matter collected and deposited on the filter is left unattended, the filtration resistance of the filter becomes large and the exhaust pressure of the engine increases, which may impede the engine output and exhaust emission performance. In general, particulate combusts spontaneously at temperatures above 500°C and becomes harmless, but the exhaust gas temperature of a diesel engine reaches 500° to 750°C in the exhaust gas passage near the combustion chamber during high-speed, high-load operation. It burns and the filter is regenerated. However, during steady running, the exhaust gas temperature is in the range of 120° to 400°C, so the particulate is not burned and the filter clogging cannot be eliminated.

Therefore, a burner for heating the exhaust gas is installed upstream of the filter, and the burner is activated when the exhaust pressure at the filter inlet reaches a preset value for a specific engine speed and load condition. When the mileage exceeded a predetermined value, or by using a timer, the burner was activated at regular intervals to burn particulate and unclog the filter.

However, these heating burners are equipped with fuel control valves to supply or restrict fuel, but if this fuel control valve malfunctions, fuel may be supplied even when the burners are not in operation, causing problems in the exhaust pipe. The drawback was that the fuel dripped from the end, causing pollution, and if the spark plug operated under such conditions, a large amount of fuel would ignite, leading to an explosion or other accident. If a solenoid valve is further added to the piping to the burner in order to solve this drawback, a new drawback arises in that the number of failure points further increases.

An object of the present invention is to provide a particulate purification device that eliminates the above-mentioned conventional drawbacks and does not require a burner in the exhaust pipe.

This object is characterized by comprising a heat-resistant filter for collecting particulate matter provided in the exhaust gas passage, and an exhaust gas recirculation means for recirculating an excessive amount of exhaust gas to a specific cylinder among the plurality of cylinders. This is achieved by a particulate purification device.

The illustrated embodiment will be described in detail below.

In the figure, reference numeral 1 indicates an engine body, and an intake manifold 2 and an exhaust manifold 3 are attached to the right side of the engine body 1 in the figure. In this case, the engine is a 4-cylinder in-line type, and the manifolds are connected to each of the 4 cylinders. An exhaust pipe 4 is connected to the exhaust manifold 3, and a filter device 5 is interposed in the exhaust pipe 4. The filter device 5 includes a heat-resistant filter 8 elastically supported and mounted in a case 6 via a stainless steel corrugated plate 7. The heat-resistant filter 8 is made of, for example, honeycomb-shaped ceramic, ceramic-coated wire mesh, or glass fiber fabric, and has a structure and heat resistance suitable for collecting and burning fine particles with an average diameter of 0.3 μm. .

Intake pipe 9 connected to intake manifold 2
A main EGR device 10 is attached to the . main
The EGR device 10 includes a valve 11, a valve body 12, and a negative pressure chamber 1.
3, etc., and causes the combined force of the pressure in the negative pressure chamber 13 and the spring 14 to act on the valve 11. Furthermore, in detail, the valve body 12 forms an L-shaped passage and has a bypass 15 connected to the intake pipe 9 and the exhaust pipe 4.
The valve 11 is supported to be able to shut off the L-shaped passage, and opens and closes the L-shaped passage by the exhaust pressure and intake pressure acting on both sides of the valve 11 and the combined force. It is designed to recirculate or restrict exhaust gas to the intake system. The negative pressure chamber 13 communicates with a vacuum tank 17 via a control valve 16, and the vacuum tank 17 is connected to a vacuum pump 19 driven by a crank pulley 18.

Next, the auxiliary EGR device 10, which is a feature of the present invention,
Since A is the same as the configuration of the main EGR device 10 described above, the parts have the same names, the suffix A is added to the reference numerals, and the description of each part is omitted.

The auxiliary EGR device 10A is attached to a branch pipe 2a connected to a specific cylinder among the four cylinders, for example, the cylinder at the top end in the figure. That is, the valve 11A returns the exhaust gas to the branch pipe 2a via the bypass 15 by the combined force of the exhaust pressure and intake pressure acting on both sides of the valve 11A, the negative pressure in the negative pressure chamber 13A, and the spring 14A. to do or limit. Adjustment of the negative pressure in the negative pressure chamber 13A is performed through the operation of the control valve 16A.
Commands to 6A are issued automatically or manually by known means (not shown).

In the above configuration, the main EGR device 10 operates under predetermined conditions while the vehicle is running to reduce NOx and to a degree that does not excessively generate smoke components and particulate matter, that is, the EGR rate is 0 to 50.
It is controlled within a range of %.

Now, when a predetermined amount of particulate matter is deposited on the heat-resistant filter 8, the control valve 16A is activated automatically or manually, the negative pressure in the negative pressure chamber 13A is strengthened, the valve 11A is pulled up, and the exhaust gas is bypassed. 15 to the branch pipe 2 through the valve body 12A.
a and is first refluxed to the cylinder. What is important in this case is that the EGR rate is carried out at an excess rate exceeding approximately 50%, and as a result, although the maximum temperature inside the cylinder is lowered, combustion is prolonged and the temperature in the latter half of combustion is lowered. It gets expensive. Therefore, since the particulate is discharged from the cylinder in a high temperature state, the heat-resistant filter 8 is heated and the temperature rises, so that the particulate can be combusted.

In this way, the present invention increases exhaust temperature by recirculating excess exhaust gas only in specific cylinders by installing a dual EGR device, and since all cylinders other than the specific cylinder are in steady operation, there is no deterioration in drivability. Can be ignored.

In this embodiment, the present invention is applied to an engine equipped with a main EGR device, but it goes without saying that the present invention is not limited to this and can be applied to an engine without an EGR device.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an example of a particulate matter purifying device according to the present invention. 1...Engine body, 2...Intake manifold, 4...Exhaust pipe, 5...Filter device, 8...
...Heat-resistant filter, 10A...Auxiliary EGR device.

Claims (1)

[Scope of utility model registration request] A particulate matter purification device comprising: a heat-resistant filter for collecting particulate matter provided in an exhaust gas passage; and an exhaust gas recirculation means for recirculating an excessive amount of exhaust gas to a specific cylinder among a plurality of cylinders. .