JPH0436009A - Backwash regeneration unit for particulate filter - Google Patents

Abstract

PURPOSE:To efficiently perform backwash-regeneration to reduce the quantity of backwashing air by injecting highly pressurized air in sequence to each area of a particular-filter while some areas to which highly pressurized air is not injected are ensured. CONSTITUTION:Plural bakcwashing air nozzles 8a - 8d are installed on the downstream side of a filter 1 so that their jets 9a - 9d are respectively opposed to the downstream end face of the filter 1, and the jets are positioned respectively at nearly middle parts of several areas obtained by dividing the cross section of the passage of the filter. Particulates adhered to the whole filter 1 are blown down toward the upstream side in two operations by highly pressurized air injected from the bakcwashing air nozzles 8a, 8b and 8c, 8d. Thus, no torque- down of an engine is generated even during power running, loading of the whole filter 1 is efficiently eliminated, and the quantity of backwashing air can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for backwashing and regenerating a particulate filter for removing particles such as soot from engine exhaust gas.

[Prior art] In recent years, as demands for environmental purification have increased, regulations on automobile exhaust gas have tended to be tightened. Especially in diesel engine vehicles, NOx (nitrogen oxides) and particulates (in exhaust smoke) have been Particulate matter) regulations are being tightened.

The NOX can be reduced by lowering the combustion temperature by, for example, delaying the fuel injection timing, but on the other hand, particulates increase. For this reason, a particulate filter is provided in the exhaust passage of the engine to remove particulates.

If the particulate filter becomes clogged due to the accumulation of trapped particulates, the exhaust resistance increases and the engine output decreases, so it is necessary to periodically regenerate the particulate filter.

Fig. 4.5 shows an example of a conventional backwash regeneration device, in which a large number of elements la such as ceramic honeycomb filters and shields that alternately close the upstream and downstream opening ends formed between the elements la are used. A particulate filter l (hereinafter simply referred to as a filter) consisting of a material 1b is housed in a trap casing 2, and an exhaust gas pipe 4 for guiding engine exhaust gas 8 into the filter 1 is connected to the upstream side of the trap casing 2. At the same time, a clean gas exhaust pipe 5 for discharging the clean gas 3° from which particulates have been removed in the filter I is connected to the downstream side, and an air pipe 6 is further connected to the downstream side of the trap casing 2. A backwash air nozzle 8 connected to the air tank 7 via the backwash air nozzle 8 is attached so that its injection port 9 faces the downstream end face of the filter 1.

A control valve 10 such as a solenoid valve is provided in the middle of the air pipe 6, and the control valve 10 receives detection signals 13. It is opened and closed in response to a drive signal 16 from a control device 15 that calculates the pressure loss of the exhaust gas 3 due to the filter 1 by calculating the differential pressure based on the filter 14.

In the figure, 17 represents a particulate reservoir integrally formed on the upstream side of the trap casing 2, and 18 represents a heater disposed in the particulate reservoir 17.

During normal operation when the filter 1 is not clogged, the differential pressure between the pressures detected by the pressure detectors 11 and 12 does not exceed the set value, so the control valve 10 is closed and the exhaust gas pipe is closed. Particulates in the exhaust gas 3 guided from the trap casing 2 into the trap casing 2 are collected by the filter 1 when passing through the filter 1, and the exhaust gas 3 becomes a clean gas 3'', and the clean gas 3'' is passed through the clean gas discharge pipe. It is discharged from 5.

When particulates accumulate in the filter l due to operation for a certain period of time and the differential pressure between the pressures detected by the pressure detectors 11 and 12 exceeds the set value, the control device 15 sends a drive signal I6 to the control valve 10. The control valve IO is opened for a short time, and the high-pressure air in the air tank 7 is supplied into the filter 1 from the injection port 9 of the backwash air nozzle 8 as a backwash flow.

When high pressure air is ejected from the downstream side of the filter 1 to the upstream side,
The particulates adhering to the filter 1 are blown off to the upstream side by the high-pressure air, thereby eliminating the clogging of the filter 1, reducing the exhaust resistance, and making it possible to collect particulates again. The blown particulates fall into the particulate reservoir 17 and are incinerated by the heat of the heater 18, which is heated by energization.

However, in the above-mentioned method for backwashing and regenerating particulate filters, the backwash air nozzle 8 is either circular or is disposed at the center of two shafts of the trap casing, so the backwash flow does not spread throughout the entire body. As a result, while the axial center of the filter 1 is efficiently backwashed and regenerated, the outer periphery of the filter 1 is not well distributed by backwashing. However, it has the disadvantage that particulates remain.

For this reason, a plurality of backwash air nostles 8 are provided and high pressure air is injected from these to the filter 1 at the same time, or
By providing a backwash air nostle (not shown) that can spray high-pressure air evenly over the entire downstream end face of the filter 1, particulates can be efficiently removed over the entire filter 1 by opening a portion of the filter 1. It is believed that

[Problem to be solved by the invention] However, as described above, backwashing regeneration of the filter 1 is performed using a plurality of backwashing air nozzles 8 or a backwashing air nozzle capable of injecting high-pressure air to the entire downstream end face of the filter 1. During backwash regeneration, the exhaust resistance of the engine becomes extremely large due to the high-pressure air blown over the entire downstream end face of the filter, leading to a reduction in the torque of the engine. It was only possible to backwash and regenerate the filter 1 during rotation.

Therefore, if the filter 1 becomes clogged when the exhaust flow rate is low, it is necessary to postpone the backwashing and regeneration of the filter 1 until the engine rotates at low speed. I could have pushed it further.

In view of these circumstances, the present invention aims to provide a method for backwashing and regenerating a particulate filter, which allows backwashing and regeneration even when the particulate filter is in use.

[Means for Solving the Problems] The present invention provides a method in which high-pressure air is not injected from the downstream side of a particulate filter installed in the middle of an exhaust passage to each region obtained by dividing the flow path cross section of the particulate filter into a plurality of regions. It is characterized by sequentially injecting high-pressure air while securing a certain area.

[Function] Therefore, when a certain amount of particulates accumulates in the particulate filter, high-pressure air is injected from the downstream side of the particulate filter to perform backwash regeneration.
During backwash regeneration, a region is secured where high-pressure air is not injected, so exhaust gas can pass through this region, and an increase in exhaust resistance can be suppressed.

[Implementation example] Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an example of an apparatus for carrying out the method of the present invention, and the parts labeled with the same reference numerals as in FIGS. 4 and 5 represent the same parts.

A plurality of (four in the figure) backwash air nozzles 8a, 8b, 8c, 8d are installed downstream of the filter l, and their injection ports 9a, 9
b, 9c, and 9d are arranged so as to face the downstream end face of the filter l, respectively, and to be located approximately at the center of each region obtained by dividing the flow path cross section of the filter l into a plurality of regions, and the backwash air nozzles 8a, 8
b is connected to the air pipe 6a extending from the air tank 7 via the control valve lea, and is connected to the backwash air nozzles 8c, 8.
d branches from the upstream side of the control valve 10a of the air pipe 6a and connects to the air pipe 6b, which is provided with a control valve 10b midway.

During normal operation when the filter l is not clogged, particulates are collected by the filter l as in the case of the conventional example shown in Figs. 4 and 5. When particulates accumulate in the filter l and the differential pressure between the pressures detected by the pressure detectors 11 and 12 exceeds a set value, the control device 15 first outputs a drive signal lea to the control valve 10a, and the control The valve 10a is opened for a short time, and the high-pressure air in the air tank 7 is injected from the jets 09a, 9b of the backwash air nozzles 8a, 8b to the jet port 9a of the filter 1.

Particulates adhering to the area facing 9b are blown off to the upstream side.

At this time, the exhaust gas 3 is injected into the injection port 9c of the filter l.

It passes through the area opposite to 9d, that is, the area where backwash air is not blown.

When the backwashing and regeneration of the area facing the injection ports 9a and 9b of the filter 1 is completed, the control device 15 outputs the drive signal 16b to the control valve 10b as described above, and the control valve 10
b is opened for a short time, and high-pressure air in the air tank 7 is injected from the injection ports 9c and 9d of the backwash air nozzles 8c and 8d, removing particulates that had adhered to the area facing the injection ports 9c and 9d of the filter l. Or it will be blown down to the upstream side.

At this time, the exhaust gas 3 passes through a region facing the injection ports 9a and 9b of the filter I, which has already been backwashed and regenerated.

The particulates that have adhered to the entire filter l are removed from the backwash air nozzles 8a, 8b, and 8c.

The high-pressure air injected from 8b is blown down to the upstream side in two parts, and this effectively eliminates the clogging of the entire filter 1 without causing a reduction in engine torque even when the engine is running, reducing exhaust resistance. The particulates can be collected again, and the dynamic pressure of the high-pressure air injected from the backwash air nozzles 8a, 8b, 8c, and 8d can be effectively used for backwashing, so the amount of backwash air can be reduced. It is also possible to do so. The blown particulates fall into the particulate reservoir 17 and are incinerated by the heat of the heater 18, which is heated by energization.

FIG. 3 shows another example of an apparatus for carrying out the method of the present invention, in which an expansion chamber 2 is provided between an inlet exhaust pipe 19 and an outlet exhaust pipe 20.
A filter 1 is incorporated into an expansion chamber 21 of an expansion type muffler 22 formed by a filter 1, and the expansion chamber 21 is defined from the filter 1 into an upstream expansion chamber 21a and a downstream expansion chamber 21b. Inside the side expansion chamber 21b, backwash air nozzles 8a, 8b, 8c, and 8d, which are exactly the same as those shown in FIG. 1.2, are provided.
is arranged.

A particulate reservoir 11523 communicating with the upstream expansion chamber 21a is provided at the lower part of the muffler 22, and a heater 24 is provided within the particulate reservoir 23.

During normal operation when the filter 1 is not clogged, the differential pressure between the pressures detected by the pressure detectors 11 and 12 does not exceed the set value, so the control valves 10a,
The fob is closed, and particulates in the exhaust gas 3 flowing into the expansion chamber 21 from the inlet exhaust pipe 19 are collected by the filter 1 when passing through the filter 1, and the exhaust gas 3 becomes clean gas 3. By passing through the filter I in the expansion chamber 21, the silencing effect is further enhanced compared to when only the expansion chamber 21 is used, and the clean gas 3' is discharged from the outlet exhaust pipe 20.

If particulates accumulate in the filter 1 during operation for a certain period of time and the differential pressure between the pressures detected by the pressure detectors 11 and 12 exceeds the set value, as in the case of the embodiment shown in Fig. 1.2. In exactly the same way, the particulates that had adhered to the entire filter 1 are blown off to the upstream side in two parts by high-pressure air injected from the backwash air nozzles 8a, 8b, 8c, and 8d. Also, the clogging of the entire filter I is efficiently eliminated without causing a reduction in engine torque, the exhaust resistance is reduced, and particulates can be collected again, and the backwash air nozzle 8a.

Since the dynamic pressure of the high-pressure air injected from 8b, 8c, and 8d can be effectively used for backwashing, it is also possible to reduce the amount of backwash air. The blown particulates fall into the particulate reservoir 23 and are incinerated by the heat of the heater 24, which is heated by energization.

It should be noted that the particulate filter backwashing regeneration method of the present invention is not limited to the above-described embodiments, and may be applied to various types of particulate filters, without departing from the gist of the pond water invention. Of course, various changes can be made within the scope.

[Effects of the Invention] As explained above, according to the method for backwashing and regenerating a particulate filter of the present invention, backwashing and regeneration can be efficiently performed without reducing engine torque even when the engine is running. Moreover, the excellent effect of reducing the amount of backwashing air can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an example of an apparatus for carrying out the method of the present invention, Fig. 2 is a view taken along the ■-■ arrow in Fig. 1, and Fig. 3 is a view of another apparatus for carrying out the method of the present invention. FIG. 4 is a side sectional view showing an example, FIG. 4 is a side sectional view showing a conventional example, and FIG. 5 is a view taken along arrow V-■ in FIG. ■ is particulate filter, 2 is trap casing, 3 is exhaust gas, 3' is clean gas, 4 is exhaust gas pipe, 5 is clean gas discharge pipe, [ia, 6b is air piping, 7 is air tank (pressure source), 8a , 8b, 8c. 8d is a backwash air nozzle, 9a, 9b, 9c, 9d are injection ports, 10a, 10b are control valves, 19 is an inlet exhaust pipe, 20
2 represents an outlet exhaust pipe, and 22 represents a muffler.

Claims (1)

[Claims] 1) From the downstream side of the particulate filter installed in the middle of the exhaust passage, high-pressure air is sequentially injected into each region into which the cross section of the particulate filter is divided into multiple parts, while ensuring an area where high-pressure air is not injected. A method for backwashing and regenerating a particulate filter.