JPH0385315A - Exhaust gas purifying device - Google Patents

Abstract

PURPOSE:To flow exhaust gas into any one of a double filter selectively and purify the exhaust gas continuously by connecting branch exhaust passages respectively comprising a valve to the double filter provided on the way of an exhaust passage. CONSTITUTION:Each filter 1, 2 of the inside and the outside is respectively installed inside each housing 4, 5 of the inside and the outside, and thereafter, they are interposed on the way of an exhaust passage 6. On the other hand, the exhaust passage 6 is separated into the inside and the outside in the upstream side, while each exhaust passage 6a, 6b of the inside and the outside is respectively communicated with each filter 1, 2 of the inside and the outside. Each butterfly valve 7a, 7b for opening and closing each exhaust passage 6a, 6b is respectively provided inside each exhaust passage 6a, 6b. When any one of respective filter 1, 2 catches a certain quantity of particulate and the catching ability thereof reaches a limitation, each butterfly valve 7a, 7b is opened and closed for switching so that the other filter catches the particulate continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust gas purification device that captures particulates, etc. in exhaust gas that pose an environmental problem, and more specifically, the present invention relates to an exhaust gas purification device that captures particulates, etc. in exhaust gas that pose an environmental problem. This invention relates to an exhaust gas purification device equipped with a filter that captures particulates.

[Prior Art and Problems to be Solved by the Invention] Since /f ticulate contained in the exhaust gas of a diesel engine poses an environmental problem, it is removed using a filter.

Examples of filters include a ceramic filter 10 with a comb structure as shown in FIG. 8, and a ceramic filter 20 with a foam structure as shown in FIG.
Installed in the middle of the exhaust passage to capture particulates in exhaust gas. In the case of such an exhaust gas purification device, if particulates are captured and the filter becomes clogged, back pressure in the exhaust passage increases and exhaust efficiency decreases, resulting in a decrease in engine performance. Therefore, it is necessary to remove particulates from the filter and regenerate the filter periodically or when a preset back pressure is reached.

As a regeneration method, incineration of particulates using a burner or an electric heater has been conventionally performed. However, in the case of a burner, it lacks safety because it may cause troubles such as burner nozzle clogging and misfires, and it also has the disadvantage that the entire device becomes large.

On the other hand, in the case of an electric heater, the energy required to heat the particulates to the combustion temperature in the moving exhaust gas stream is too large, so the power supply is also large, making it difficult to install the device in a vehicle.

To solve this problem, there is a so-called dual system in which two filters 30 and 30 are installed in the middle of the exhaust passage 6, as shown in Fig. 10, and a so-called dual system, as shown in Fig. 11.
A so-called bypass system in which a bypass 65 is provided for the filter 30 has been devised. In either case, when the filter is regenerated by the electric heater, the exhaust gas flow is switched by the butterfly valve 7 to the side of the filter that is not being regenerated or to the bypass. According to these methods, the electric heater is not affected by the exhaust gas flow, so it is possible to regenerate the filter with less thermal energy.

However, in the case of the dual system, two parallel filters are required, making the entire purification device large and making it difficult to mount it on a vehicle. On the other hand, in the case of the bypass system, there is a problem in that particulates in the exhaust gas cannot be captured at all during filter regeneration.

Therefore, an object of the present invention is to provide an exhaust gas purification device that is compact as a whole and requires less thermal energy to incinerate particulates for regenerating a filter.

[Means to solve the problem]

In view of the above issues, as a result of intensive research, the inventor of the present invention created a filter that captures particulates with a double structure of an inner cylinder and an outer cylinder, and created a structure in which the exhaust passage can be switched so that exhaust gas flows into either one of the filters. They discovered that by doing so, the exhaust gas purification device can be made more compact and the filter can be regenerated more efficiently, and the present invention has been completed.

That is, in the exhaust gas purification device of the present invention, a double filter in which an inner cylinder filter is arranged concentrically within an outer cylinder filter is provided in the middle of the exhaust passage, and the exhaust passage is connected to each of the filters. It is characterized by branching into two in front of the exhaust passage, and by operating a valve in the exhaust passage, exhaust gas is selectively allowed to flow into either the inner cylinder filter or the outer cylinder filter.

In addition to the above structure, if an electric heater is attached to each of the inner cylinder filter and the outer cylinder filter, the electric heater can remove the particulates trapped in the filter whose inflow of exhaust gas is blocked by operating the valve. The filter can be regenerated by incineration.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the basic structure of the exhaust gas purification apparatus of the present invention, in which 1 is an inner tube filter, 2 is an outer tube filter, and 3 is a wall material for sealing between the two filters. The arrow indicates the direction in which the exhaust gas passes. Each filter 1.2
As shown in FIGS. 2 and 3, they are separately installed in the inner and outer housings 4.5 and disposed in the middle of the exhaust passage 6. In FIG. 2, the walls of the housing 4.5 and the pipe serving as the exhaust passage 6 are shown as a single line, but in reality they have a constant thickness. The wall of the inner housing 4 is
This corresponds to the wall material 3 in FIG.

The exhaust passage 6a branches into two in front of the filter, with the inner exhaust passage 6a communicating with the inner cylinder filter 1, and the outer exhaust passage 6b communicating with the outer cylinder filter 2. Each of the exhaust passages 6a and 6b has a butterfly valve 7a inside.
7b are provided, and it is possible to switch the flow of exhaust gas by means of these valves. In the case of Figure 2,
An exhaust passage 6b leading to the outer cylinder filter 2 is opened by a valve 7b, and an exhaust passage 6a leading to the inner cylinder filter 1 is blocked.

When one filter traps a certain amount of particulates and its trapping ability decreases, the flow of exhaust gas is switched to the other filter. Then, in order to regenerate the filter whose trapping ability has decreased, the particulates are incinerated by heating with an electric heater or the like. The electric heater uses a rod-shaped object ((a) circular cross-section, (b) rectangular cross-section, (C) square cross-section, (4) oval cross-section) as shown in Figure 4 to move the heater inside the filter in the axial direction. Alternatively, as shown in FIG. 5, (e) a spiral shape or (f) a wave shape can be used to closely fit or embed the filter in front of the filter.

FIG. 6 shows a state in which six electric heaters 8 are passed through the inner cylinder filter 1, and FIG. 7 shows a state in which six electric heaters 8 are passed through the outer cylinder filter 2. Also, one filter has a fourth
The rod-shaped electric heater 8 shown in the figure may be passed through the filter, and the electric heater 8 shown in FIG. 5 may be provided on the front surface of the other filter. In any case, the method of installing the electric heater 8 is appropriately selected depending on the shape of the housing 4.5 and the position of the electric circuit.

[For production]

When exhaust gas containing particulates flows into one of the branched exhaust passages, for example, in FIG. 2, when it flows into the exhaust passage 6b whose valve is open, the particulates are captured by the outer cylinder filter 2 and the exhaust gas is purified. be done. When particulates accumulate in the outer cylinder filter 2 and the trapping ability decreases, close the valve 7b and open the valve 7a to direct the exhaust gas to the exhaust passage 6a.
to flow into. While the exhaust gas is being purified by the inner cylinder filter 1, the outer cylinder filter 2 is heated using an electric heater.
The outer cylinder filter 2 is regenerated by heating and incinerating the particulates.

In this way, while purifying exhaust gas with one filter, the operation of regenerating the other filter is repeated, thereby purifying the exhaust gas without interruption.

〔Example〕

The present invention will be explained in more detail by the following specific examples.

As shown in Fig. 6, six rod-shaped electric heaters each having an outer diameter of 2 mm and a length of 300 mm were embedded in a ceramic filter A having a cylindrical shape with an outer diameter of 118 mm and a length of 205 mm and a foam structure made of cordierite material. is. Also, the outer diameter is 177B,
As shown in Figure 7, six rod-shaped electric heaters with an outer diameter of 2 m and a length of 300 mm were embedded in a cylindrical ceramic filter B with an inner diameter of 132 m and a length of 205 m and a foam structure made of cordierite material. is.

The filter A is installed in the inner stainless steel housing 4 as shown in Fig. 3, and the filter B is installed in the outer stainless steel housing 5 to make them integral.
．． It was installed in the middle of the exhaust passage of a 3L diesel engine.

The engine was operated at a constant rotational speed of 200 rpm, and exhaust gas was allowed to flow through Filter A for 3 hours to capture particulates. Next, after switching the exhaust gas to the filter B side using a valve, an attempt was made to regenerate filter A by passing an electric current through an electric heater embedded in filter A to incinerate the particulates. As a result, the voltage was 5 volts, and the current flowing through each electric heater was 3 volts.
When the output is 3 amperes, filter A is activated after 10 minutes of energization.
has been played.

Next, after letting the exhaust gas flow through filter B for 3 hours, the exhaust gas flow was switched to the filter A side and the electric heater of filter B was energized in the same way as above. As a result, the voltage was 5 volts, and the current flowing through each electric heater was The output was set to 33 amperes, and the regeneration of filter B was completed in 12 minutes.

〔Effect of the invention〕

As described above, the exhaust gas purification device of the present invention substantially consists of one exhaust passage and a filter housed in one housing, so the structure is compact, and the exhaust gas purification is performed using two filters. You can do this efficiently without interruption.

In addition, heat of the exhaust gas is propagated from the filter side into which the exhaust gas is flowing to the filter side where the regeneration is being performed, so that the thermal energy required for filter regeneration can be reduced.

The device of the invention is particularly suitable for trapping particulates in exhaust gas, but by supporting a specific catalyst in the filter it can also purify nitrogen oxides and carbon monoxide.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a perspective view showing the basic structure of the exhaust gas purification device of the present invention, FIG. 2 is a sectional view showing the exhaust gas purification device according to an embodiment of the present invention, and FIG. 3 is a perspective view showing a housing used in the exhaust gas purification device of the present invention, FIG. 4 is a perspective view showing an electric heater used in the exhaust gas purification device of the present invention, and FIG. 5 is a perspective view showing the exhaust gas purification device of the present invention. FIG. 6 is a perspective view showing the electric heater installed in the inner cylinder filter in the exhaust gas purification device of the present invention, and FIG. 7 is a plan view showing the electric heater used in the exhaust gas purification device of the present invention. FIG. 8 is a perspective view showing a state in which an electric heater is installed in an outer cylinder filter; FIGS. 8 and 9 are perspective views showing a conventional ceramic filter; FIGS. 10 and 11 are perspective views showing a conventional exhaust gas purification device. FIG. 1 ・ ・ ・ ・ 2 ・ ・ ・ ・ 4, 5 ・ 6.61.62・ 7.71.72・ 8 ・ 1O120,30・ ・Inner tube filter・Outer tube filter・Housing・Exhaust passage・Valve・electric heater filter

Claims (4)

[Claims] (1) In an exhaust gas purification device equipped with a filter that captures particulates floating in exhaust gas, a double filter in which an inner cylinder filter is arranged concentrically within an outer cylinder filter is provided in the middle of the exhaust passage, and the exhaust passage is branched into two in front of the filter so as to be connected to each of the filters, and by operating a valve in the exhaust passage, the exhaust gas can be selectively directed to either the inner cylinder filter or the outer cylinder filter. An exhaust gas purification device characterized in that the exhaust gas is caused to flow into the exhaust gas. (2) In the exhaust gas purification device according to claim 1, a rod-shaped electric heater is provided to pass through each of the inner cylinder filter and the outer cylinder filter in the axial direction, and the inflow of exhaust gas is blocked by operating the valve. An exhaust gas purification device characterized in that particulates trapped in one of the filters can be incinerated by the electric heater. (3) In the exhaust gas purification device according to claim 1, an electric heater is provided in front of each of the inner barrel filter and the outer barrel filter, and an electric heater is provided in the filter of which exhaust gas inflow is blocked by operation of the valve. An exhaust gas purification device characterized in that captured particulates can be incinerated by the electric heater. (4) In the exhaust gas purification device according to claim 1, a rod-shaped electric heater is provided in one of the inner tube filter and the outer tube filter so as to penetrate in the axial direction, and the other is provided with an electric heater on the front surface. . An exhaust gas purification device, characterized in that the electric heater is capable of incinerating particulates trapped in the filter whose inflow of exhaust gas is blocked by operating the valve.