JPS60184917A - Device for decreasing diesel particulates - Google Patents

Abstract

PURPOSE:To facilitate the regeneration of two particulates filters provided in parallel with each other in an engine, by providing a butterfly valve, which is switched over to cause exhaust gas to flow to the filter of larger pressure loss when the temperature of the exhaust gas has risen to or over a prescribed level. CONSTITUTION:An exhaust pipe 8 is divided into two portions, in which honeycomb-structured filters 11, 12 made of a catalyst-added ceramic are provided and which are coupled to each other for confluence downstream to the filters. A butterfly valve 10 for leading exhaust gas to one of the divided portions of the exhaust pipe 8 is provided therein at the divided portions. A high-temperature gas passage 18, which communicates with a burner 17, is connected to the exhaust pipe 8 at the butterfly valve 10. When the butterfly valve 10 is in a position shown in the drawing, and particulates are being collected by the filter 11, for example, in the range of engine run in which the temperature of the exhaust gas has risen to or over a prescribed level of about 250 deg.C, the butterfly valve 10 is switched over to cause the exhaust gas to flow to the filter 11 or 12 of larger pressure difference, to regenerate the filter by only the exhaust gas.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a diesel particulate reduction device,
In particular, the present invention relates to a device structure for suitably regenerating a filter that has collected particulates.

[Background of the invention]

Currently, as a method to reduce particulates contained in diesel engine exhaust gas, particulates are collected by a filter installed in the exhaust pipe, and the pressure loss of the filter due to the collected particulates is further reduced. A method of burning particulates in a filter using a burner is mainly used. In the case of this method, complete combustion in the burner is essential, and for this purpose it is desirable that the burner combustion chamber is not subject to pressure fluctuations in the exhaust pipe.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 57-65813, a method has been used in which the particulates in the filter are combusted in a state where the burner combustion chamber and the exhaust pipe are separated using a valve.

That is, as schematically shown in FIG. 1, two filters 2.3 are arranged in the exhaust passage of the diesel engine 1, and the exhaust gas and high temperature gas from the burner 4 are introduced into the inlets of these filters 2.3. Two valves 5 and 6 are provided to selectively introduce the exhaust gas, and the exhaust gas is allowed to flow through the filters 2 and 3, which has a lower pressure drop, and the high temperature gas from the burner 4 is allowed to flow through the other filter. When the pressure drop of the filter increases, the two valves 5 and 6 are switched in the opposite direction.
A method is used in which exhaust gas is allowed to flow through a filter that has been completely regenerated using high-temperature gas, in order to regenerate a filter that has experienced a high pressure drop.

However, even though the exhaust gas has a certain amount of thermal energy, this method relies only on the high-temperature gas from the burner to regenerate the filter, which has the disadvantage that the overall efficiency of the device is low. be.

[Purpose of the invention]

An object of the present invention is to provide a diesel particulate reduction device that can efficiently burn particulates in diesel engine exhaust.

[Summary of the invention]

The present invention makes the flow of exhaust gas and the flow of combustion gas face each other, and provides one valve to divide each flow into left and right sides.This valve also allows the filter pressure drop to be a predetermined pressure drop reduction, and to reduce the exhaust gas flow. When the temperature is above a predetermined temperature, the exhaust gas is controlled to flow through the filter with the higher pressure loss.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention,
Exhaust gas discharged from the diesel engine 1 is collected in an exhaust manifold 7, further passes through an exhaust pipe 8, and reaches an exhaust pipe population 9. Here, since only the passage leading to the filter 11 is opened by the bubble 10, the exhaust gas passes through the filter 11.

Filter 11 and filter 12 are catalyst-added ceramic honeycomb structured filters, and the exhaust gas passes through the porous walls of the cells. At this time, particulates contained in the exhaust gas are collected on the porous walls. Then, the particulates are reduced and the exhaust gas is released into the outside air from the exhaust outlet 13. Thereafter, the filter ventilation resistance increases with the increase in particulate matter 1 to the amount of collection. The ventilation resistance is detected by the pressure sensor 14, and the exhaust temperature is detected by the temperature sensor 15.

On the other hand, the shaft 16 of the valve 10 is rotated via a link mechanism (not shown) whose stroke is obtained by controlling the air pressure of a servo diaphragm, and this rotation switches the valve 10 fixed to the throttle shaft 16. By switching the four valves 10 to the state indicated by the broken line (state ■), the exhaust gas that has passed through the exhaust pipe 8 reaches the filter 12 and collects particulates.

On the other hand, at this time, the high temperature gas generated by the burner 17 is applied to the filter 11 which has sufficiently collected particulates through the high temperature gas passage 18.

Then, this amount of heat oxidizes the particulates in the filter. At this time, the high-temperature gas passage 18 is blocked off from the exhaust gas by the valve IO, so that stable combustion is performed.

Here, combustion in the burner will be explained.

Fuel, which is pumped from the fuel tank to the burner 17 through the fuel pipe 19, is metered and injected by a valve provided in the fuel injection section of the burner 17. In this case, the valve is turned on and off depending on the duty signal,
The duty signal has a duty width determined in order to obtain an appropriate amount of heat depending on the filter condition, and is sent to the electromagnet inside the burner via the signal line 20, which turns on the valve provided at the tip of the electromagnet. Turn off. The injected fuel is mixed with air sent through an air pipe 21 by an air pump (not shown) and ignited by a spark plug 22. In this case, the air sent through the air pipe 21 includes primary air swirled by the swirler 23 and secondary air that is supplied from the outside of the liner 24 to the combustion chamber 25 through the wall hole.
Next, it separates into air.

Next, the control method will be explained using FIGS. 3 to 6. As shown in FIG. 3, the valve 10 can be set in two states: state I and state (3). That is, a state in which combustion necessary for filter regeneration is performed (operating state) and a stopped state can be set. By combining these states, the system can select one of the four states shown in FIG. These four states result in the filters 11, 12 being in the state shown in FIG.

Here, the usage state refers to the state in which particulates in exhaust gas are collected by the filter, and the regeneration state refers to the state in which the particulates are oxidized by the high-temperature gas of the burner, and the filter with increased pressure loss is It means that it is being restored (regenerated), and the standby state means that neither exhaust gas nor high-temperature gas passes through it. here,
For convenience of explanation, these four states are named A, B, C, and D as shown in FIGS. 4 and 5.

The particulates trapped in the catalyst addition filters 11 and 12 oxidize and disappear at a temperature of about 250°C. On the other hand, the engine exhaust gas temperature changes depending on the operating condition as shown in the graph in Figure 6.
In the above operating range, filter regeneration is performed during use.

Therefore, filter pressure loss has a negative effect on fuel efficiency and drivability.
, 15Kg/cJ (400Q/r@hr) or less, when the exhaust temperature is 250℃ or higher, the state B=D is switched so that the exhaust gas flows through the filter with the higher differential pressure, and 0
．． 1.5Kg/c! In this case, if the state is changed to AorC and regeneration is performed by the burner 17, the thermal energy of the exhaust gas can also be used, improving the overall efficiency.

If the above-described operation is expressed in a flowchart, it will be as shown in FIG.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the heat of exhaust gas can be effectively used for filter regeneration, so the number of burner operations can be reduced, and a decrease in fuel efficiency can be minimized. Controlling one valve has the effect of efficiently burning particulates.
It has very practical advantages in terms of economy.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional diesel particulate reduction device, Fig. 2 is a schematic diagram showing an embodiment of the present invention, and Fig. 3 is a schematic diagram showing an embodiment of the present invention.
The figure is a schematic diagram showing the valve state, FIG. 4 is an explanatory diagram showing the filter state, FIG. 5 is a diagram explaining the combination of the novena and valve states, and FIG. 6 is a graph showing the exhaust gas temperature in the engine state. FIG. 7 is a flowchart showing the overall control. DESCRIPTION OF SYMBOLS 1... Diesel engine, 7... Exhaust manifold, 8... Exhaust pipe, 9... Exhaust pipe inlet, 10... Valve, 11... Filter, 13... Exhaust outlet, 14...
... Pressure sensor, 15 ... Temperature sensor, 16 ... Throttle shaft, 17 ... Burner, 18 ... High temperature gas passage, 19 ... Fuel pipe, 21 ... Air pipe, 2
2...Spark plug, 23...Swirer, 24...Liner, 25...Combustion chamber. Agent Patent Attorney Akio Takahashi Engraving of drawings (no changes to the content) 19th Kaya February/, Ryo) Quantity Sword High School Force '4X Field 1 1 Input 1 $4 Gokaya 5 Mekaya Otsu Large] Engineering〉Jinro Tang Yunka (To rKakari Kaya 7 Figure Display of the case of Mr. Kazuo Wakasugi, Commissioner of the Patent Office, 1982 Patent Application No. 38573, Mr. Osamu)

Claims (1)

[Claims] 1. Two filters that collect particulates contained in diesel engine exhaust gas, a burner that supplies the high-temperature gas necessary to oxidize the particulates collected by these filters, and the high-temperature gas of this burner. A diesel particulate reduction device comprising a butterfly valve that distributes exhaust gas to the two filters, wherein the two filters are catalyst coated filters, and when the exhaust gas temperature rises above a predetermined temperature, the two filters are closed. A diesel particulate reduction device characterized in that the butterfly valve is switched so that the exhaust gas flows to the one with a larger pressure drop.