JPH04166604A - Exhaust gas purifing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve a flame propagation ability and prevent its cinder in the case of regenerating a filter by supplying regenerating gas into a space between the inside surface of a trap vessel and the outside surface of the filter, and arranging a regenerating gas supply means to increase flow speed of gas flowing in the peripheral part of the filter. CONSTITUTION:In an exhaust gas purifing device, a filter 1 is supported against a trap vessel 2 through a spacer member 8, and an annular space 9 is formed between the inside surface 2a of the vessel 2 and the outside peripheral surface 1a of the filter. Though an exhaust gas by-pass pipe 10 is connected to both exhaust pipes 3a and 3b so as to by-pass the filter 1, in this case, a secondary regenerating exhaust gas guiding pipe 12 to guide a part of the exhaust gas being branched off by means of a switchegear valve 11 to the annular space 9 is connected to the middle of the exhaust gas by-pass pipe 10. In the case of regenerating the filter, by supplying the regenerating exhaust gas into the annular space 9 through a gas guiding pipe 12, the exhaust gas in the peripheral part 1b of the filter can be flown to the rear edge of the filter without lowering its flow speed, so that defective regeneration of the filter can be avoided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust gas purification device installed in an internal combustion engine, and particularly to an exhaust gas purification device equipped with a particulate filter that collects diesel battiquinate discharged from a diesel engine. Regarding purification equipment.

[Conventional technology]

For example, since the exhaust gas of a diesel engine contains many exhaust particles, ie, particulates, the exhaust system of the engine is equipped with a particulate filter for collecting the particulates.

The particulate filter is made of a material with good air permeability, such as a ceramic material, and must be periodically regenerated based on the amount of particulates collected by the filter. Here, filter regeneration means that particulates are ignited and burned by energizing an electric heater wire provided at the end of the filter, thereby restoring the air permeability of the filter.

By the way, during this filter regeneration, exhaust gas is introduced into the filter in the same way as when collecting particulates in order to propagate the combustion of particulates, but normally this exhaust flow is faster in the center of the filter, and Since the filter regeneration rate is slower at the peripheral edge, there is a difference in the degree of filter regeneration, and unburned particulates tend to occur at the filter peripheral edge, resulting in poor filter regeneration. To deal with such problems, for example, Utility Model Application No. 62-14161
No. 5 discloses an exhaust gas purification device in which a diffuser plate (diffuser) is provided on the exhaust upstream side of the filter to disperse the flow of exhaust gas for regeneration also to the peripheral edge of the filter.

[Problem to be solved by the invention]

However, in the above-mentioned exhaust gas purification device, the diffusion plate disposed upstream of the filter acts as a resistance to the exhaust gas flow when collecting particulates, and there is a risk that the pressure upstream of the filter, that is, the back pressure may increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas purification device that enables complete regeneration of the peripheral edge of a filter.

[Failure to solve the problem]

To achieve the above object, the present invention provides an exhaust system that includes a filter that is installed in the exhaust system of an internal combustion engine and that collects particulates, and periodically incinerates the particulates that are collected by the filter to regenerate the filter. In the purification device, the filter is held through a gap between the inner surface of the trap container that houses the filter and the outer surface of the filter, and when the filter is regenerated, a regeneration gas is supplied into the gap and flows within the periphery of the filter. Provided is an exhaust gas purification device characterized in that it is provided with a regeneration gas supply means for increasing the flow rate of the gas.

[For production]

By introducing part of the exhaust gas or outside air into the gap located outside the filter during filter regeneration, the flow velocity of the regeneration gas around the filter periphery is increased and flame propagation due to particulate combustion in this area is reduced. This can be done to prevent burnout.

〔Example〕

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

FIG. 1 shows a schematic configuration of an exhaust gas purification device as a first embodiment of the present invention. In the figure, 1 is a cylindrical particulate filter (hereinafter referred to as a filter); Cylindrical trap containers for storage, 3a and 3b
indicate exhaust pipes connected to the front and rear ends of this trap container 2. In this embodiment, it is assumed that the exhaust gas flowing from the engine body flows from the left side to the right side in the figure, that is, from the exhaust pipe 3a toward the exhaust pipe 3b.

An electric heater wire 4 that is energized and generates heat during filter regeneration is provided near the end of the filter 1 on the exhaust upstream side, and one end of the wire 4 is connected to a relay 6 controlled by a control circuit 5.
The other end is connected to the battery 7 through the terminal, and the other end is grounded. During filter regeneration, the flame of the particulate matter in the filter ignited by the electric heater wire 4 propagates toward the downstream end of the filter l along the exhaust gas flow shown by the arrow. That is, the exhaust purification device of this embodiment is a so-called forward-flow regeneration type exhaust purification device in which the flow direction of exhaust gas during particulate collection matches the flow direction of exhaust gas during filter regeneration. The present invention can also be applied to an exhaust gas purification device of a reverse flow regeneration type in which exhaust gas flows from the downstream side of the exhaust gas toward the upstream side of the exhaust gas as shown in the figure during regeneration (described later).

According to this embodiment of the exhaust purification apparatus configured as described above, the filter 1 is held with respect to the trap container 2 via the spacer member 8 disposed along the outer circumference of the filter, and An annular gap 9 is formed between the filter 2a and the outer peripheral surface 1a of the filter 1.

Further, an exhaust bypass pipe 10 is connected to both exhaust pipes 3a and 3b so as to bypass the filter 1, and when the filter is regenerated, the exhaust gas excluding the exhaust gas necessary for particulate combustion flows to the downstream side of the filter. (See the arrow in Figure 1). Therefore, at the connection part between the exhaust pipe 3a and the exhaust bypass pipe 10, the inlet of the exhaust bypass pipe 100 is closed when collecting particulates, and all the exhaust gas from the engine body is guided to the filter 1, and when the filter is regenerated, some A first on-off valve 11 (hereinafter referred to as the first on-off valve) that opens and guides some of the exhaust gas (usually about one-tenth of the total amount of exhaust gas) to the filter 1 as exhaust gas for regeneration. ) is provided.

Furthermore, according to this embodiment, in the middle of this exhaust bypass pipe 10, there is a sub-regeneration exhaust gas for guiding some of the exhaust gas branched by the first on-off valve 11 to the annular gap 9 from the side of the filter. An introduction pipe 12 (hereinafter abbreviated as gas introduction pipe) is connected, and the other end is connected to the side of the trap container 2.

A second on-off valve 13 (hereinafter referred to as a second on-off valve) is also provided at the connection between the gas introduction pipe 12 and the exhaust bypass pipe 10, which opens to take in exhaust gas for regeneration during filter regeneration.

This second on-off valve 13 and the first on-off valve 11 are operated by an actuator 1 whose operation is controlled by a control circuit 5.
4 and 15.

The above is the schematic configuration of the exhaust gas purification device according to this embodiment.

The operation and effects of this device will be described below with reference to FIG. 2, which shows the flow of exhaust gas during filter regeneration with arrows.

Generally, when regenerating a filter, if exhaust gas is introduced only from the exhaust upstream end of the filter as in the past, a certain flow rate of exhaust gas is secured at the center of the filter, but at the periphery of the filter, the exhaust gas flows outward. The flow velocity of the exhaust gas decreases rapidly due to the resistance from the inner wall of the trap container where it is located, and the particulate combustion flame disappears in the middle of the filter, so the filter
Unburnt particinilate remains in the shaded area in the figure. However, according to this embodiment, the exhaust gas for regeneration is supplied not only from the end face side of the filter but also from the side of the filter through the gas introduction pipe 12 into the annular gap 9. The exhaust gas flows to the rear end of the filter without reducing its flow velocity, so the flame reaches the rear end, and even the particulates in the shaded area can be sufficiently burned, thereby avoiding poor filter regeneration. Incidentally, according to this embodiment, the filter peripheral portion 1b is regenerated quickly (because of this, the regeneration time is shortened, the filter regeneration cost is reduced, and the temperature gradient between the filter central portion 1c and the peripheral portion is also low). From becoming,
Thermal stress during regeneration is alleviated and the durability of the filter is also improved.

The present invention is not limited to the embodiments described above, and various embodiments can be considered. These embodiments will be described below with reference to each figure. The figures show the operating state of the device during filter regeneration, and the same elements as those in the previous embodiment are given the same numbers and have similar configurations. For elements, dash (
’) will be added.

First, FIG. 3 shows a gas introduction pipe 1 as a second embodiment of the present invention.
One end of 2' is opened to the atmosphere, and an air pump 16 is provided in the middle to introduce outside air to the side of the filter during filter regeneration, thereby suppressing a decrease in the flow velocity of exhaust gas around the periphery of the filter. It is something.

The third embodiment shown in FIG. 4 is an example in which the present invention is applied to a backflow regeneration type exhaust gas purification device. 3b (or the trap container 2), and during filter regeneration as shown in the figure, a part of the exhaust gas flowing back to the filter 1 via the exhaust bypass pipe 10' is taken in by the second on-off valve 13'. ing. In this figure, 11' is a first opening/closing valve that guides the exhaust gas to the exhaust bypass pipe 10' by occupying the valve position as shown by the solid line during filter regeneration, and 17 is the first opening/closing valve that guides the exhaust gas through the exhaust bypass pipe 10'. An opening/closing valve 'i3 allows a portion of the exhaust gas to flow back toward the filter, and 18 indicates an exhaust gas flow pipe that sends the exhaust gas after the regeneration process to the downstream side of the filter.

Furthermore, the fourth embodiment shown in FIG. 5 is the above-mentioned backflow regeneration type exhaust gas purification device in which the regeneration gas introduced to the side of the filter is part of the outside air as in the embodiment in FIG. 3. .

Various embodiments of introducing the regeneration gas to the side of the filter have been described above, but in common with each embodiment, other methods of igniting particulates include the electric heater described above. As shown in the illustration, an intake throttle valve 1 is installed in the intake system of the engine.
9 may be provided to guide high-temperature exhaust gas to the filter by narrowing down the intake air during filter regeneration, and ignite particulates.

In addition, as shown in Figure 7, during filter regeneration,
The outside air may be heated by the burner 18 and guided to the filter.

〔Effect of the invention〕

As explained above, according to the present invention, by introducing the regeneration gas into the gap outside the filter during filter regeneration, the flow velocity of the regeneration gas at the peripheral edge of the filter is increased, and the unburned particulates in this area are increased. can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an exhaust gas purification device according to a first embodiment of the present invention; Fig. 2 is a diagram showing the flow state of the exhaust gas in the filter to explain the action and effect of the exhaust purification lid of the present invention; A device configuration diagram illustrating a second embodiment of the present invention; FIG. 4 is a device configuration diagram as a third embodiment in which the present invention is applied to a backflow regeneration type exhaust purification device; FIG. 5 is a device configuration diagram illustrating a second embodiment of the present invention Fig. 6 is an apparatus block diagram illustrating a method of igniting particulates that is different from the method of igniting particulates using an electric heater; FIG. 1... Filter, 2... Trap container, 5
...Control circuit, 8.Spacer member, 9.
...Gap, 10...Exhaust bypass pipe, 11
...first on-off valve, 12...gas introduction pipe, 13.
...Second on-off valve.

Claims (1)

[Claims] 1. In an exhaust gas purification device that includes a filter that is installed in an exhaust system of an internal combustion engine to collect particulates and periodically incinerates the particulates collected by the filter to regenerate the filter, a trap container that stores the filter. Regeneration gas supply means that holds the filter through a gap between the inner surface of the filter and the outer surface of the filter, and supplies regeneration gas into the gap during filter regeneration to increase the flow rate of the gas flowing within the peripheral edge of the filter. An exhaust purification device characterized by being provided with.