JPS63235614A - Exhaust gas filter device - Google Patents

Abstract

PURPOSE:To lower pressure by providing a back pressure detecting part in the exhaust pipe of a Diesel engine, controlling a valve provided in said exhaust pipe in accordance with the output of said detecting part, and varying the flow rate of exhaust gas which flows into plural exhaust gas filter. CONSTITUTION:In a device in which plural (two in the figure) filter devices which are formed by housing filter members 5 in filter containers 4 for collecting fine particles in exhaust gas are provided in the exhaust system of a Diesel engine, a detector 2 for detecting back pressure is provided in an exhaust manifold 1 on the upper course side of the filter devices. Also, a valve 3 is provided on the joint part of the branch pipe lines leading to each filter container of the exhaust manifold 1. And, the output signal of the detector 2 is inputted into an electric control device 6, to control the opening of the valve 3 in the direction of reducing the detected back pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas filter device for a diesel engine.

Conventional technology In recent years, in order to protect the atmosphere and the environment, there has been increasing interest in suppressing particulate emissions emitted by diesel engines. In the United States in particular, very strict regulations targeting diesel vehicles will soon be introduced. It's being done.

One of the most promising ways to remove these particulates is to physically collect them with a filter installed in the exhaust system, deposit the particulates, and then burn them to regenerate the filter. Various studies are being conducted. This work is called regeneration.

As a method for this regeneration, there is a method in which a heating device is provided upstream of the filter on the engine side to raise the exhaust gas temperature to the ignition temperature of particulates and incinerate them. In this method, if a heating device is placed directly in the exhaust gas path from the engine, the heat of the heating device is absorbed by the heat capacity of the exhaust gas, and an enormous amount of combustion is required to sufficiently burn particulates. As one solution to this problem, Japanese Patent Application Laid-open No. 118514/1983 discloses a method in which a bypass path separate from the filter is provided in the exhaust gas path, so that when the heating device is operating, the exhaust gas from the engine flows toward the bypass path. things are listed.

Furthermore, Japanese Patent Laid-Open No. 58-101210 discloses a method in which the upstream side of the exhaust gas path of the filter is separated into a regeneration side and an exhaust gas flow side using a switching valve when the regenerator 3 is turned off.

However, in the method disclosed in Japanese Patent Application Laid-Open No. 56-118514, particulates are released into the atmosphere along with the exhaust gas during regeneration, and the effect of the filter is halved. Generally, in this type of device, the filter and the container containing it also serve as a muffler (silencer), but here a muffler is required in the bypass path. On the other hand, in Japanese Patent Application Laid-Open No. 58-101210, the regeneration part and the exhaust gas flow in one filter during regeneration, and the parts coexist, so a large thermal stress is generated inside the filter and the filter may be destroyed. .

Therefore, a method can be considered that uses a plurality of filters and switches between the filter through which exhaust gas flows and the filter through which generation is performed during regeneration.

Problems to be Solved by the Invention Compared to the case of using a single filter, this method of using multiple filters does not release unpurified exhaust gas during regeneration, and the filters are not destroyed by thermal stress. However, since each filter is sequentially regenerated, there is a difference in regeneration timing between the filters. Therefore, by the time all filter glue generation is completed, fine particles have already been deposited on the filters that were regenerated initially. Therefore, a difference occurs in the amount of deposited particulates between the filters. It has been discovered that in this case, the back pressure increases compared to when particles are deposited on all filters on average.

An object of the present invention is to provide an exhaust gas filter device that solves the above problems.

Means for Solving the Problem The diesel engine has a detection section installed in the exhaust pipe for detecting back pressure, and a valve provided in the exhaust pipe is controlled according to the output of the detection section to control each filter. The structure is designed to minimize back pressure by changing the flow rate of exhaust gas flowing through the exhaust gas.

The present invention is based on the discovery that back pressure is reduced by adjusting the flow of exhaust gas to the filter with a smaller amount of particulate matter. With the above configuration, by changing the angle of the valve provided in the exhaust pipe and controlling the flow rate of exhaust gas flowing between each filter, it is possible to minimize back pressure.

Embodiment Hereinafter, a case in which the number of filters is two will be described in detail as an embodiment of the present invention with reference to the accompanying drawings. In FIG. 1, 1 is an exhaust gas manifold, 2 is an exhaust gas pressure detector, 3 is a valve, 4 is a filter container, 6 is a filter member, and 6 is an electric control device. A well-known sensor is provided as the detection unit 2, and the detected value is input to the electric control device 6. The opening degree of the valve 3 can be arbitrarily controlled by a signal from the electric control device 6. There is a filter member 6 in the filter container 4. As the filter member 6, for example, a heat-resistant fibrous ceramic sintered body described in JP-A-68-174212 or a material similar thereto may be used. Can be done. Further, the shape of the exhaust pipe at the rear of the filter can be any shape. An example of a combustion device is a burner.

A heating wire or similar device can be used.

Next, a routine of an example of control performed by the electric control device 6 will be explained using FIG. 2. In the figure, aNt represents each step. In a, the boat and data to be used are initialized, in b the back pressure is detected, in C the valve is driven, and in d the back pressure is detected again. Determine whether the back pressure has decreased with e.
If it decreases, it goes to C. If it increases, it goes to f. f to return to the previous valve position.

The above routine monitors back pressure and controls the valves to minimize back pressure.

Although this embodiment deals with the case where two filters are used, the same effect can be obtained when two or more filters are used.

Effects of the Invention According to the present invention, by controlling the valve while detecting the back pressure, the flow rate of exhaust gas flowing into the filter can be easily controlled and the back pressure can be easily reduced, thereby easily improving the efficiency of the diesel engine. It is possible to obtain extremely useful effects in practice.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the principle of an exhaust gas filter device according to an embodiment of the present invention, and FIG. 2 is a flow chart for explaining the operation of the electric control device of the same device. 1...Exhaust gas manifold, 2...Exhaust gas pressure detection section, 3...Valve, 4...
...Filter container, 6...Filter member, 6.
...Electric control device. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
-Ichiki Mannu 7 Nifold 4---Filter Water

Claims (1)

[Claims] An exhaust gas filter device that is disposed in the exhaust system of a diesel engine and has a plurality of filters for collecting particulates in the exhaust gas, and has an exhaust gas pressure detection section that detects back pressure provided in the exhaust pipe. , an exhaust gas filter device configured to control back pressure by controlling a valve provided in an exhaust pipe according to the output of the exhaust gas pressure detection section to change the flow rate of exhaust gas flowing between each filter. .