JPH0650127A - Particulate removal device - Google Patents

Abstract

PURPOSE:To provide a particulate removal device capable of backwashing without using air in an air tank at all. CONSTITUTION:Filters 3a, 3b provided on exhaust gas flow passages 2a, 2b from an engine, a first opening and closing valves 5a, 5b provided on the downstream of the filters 3a, 3b, first by-pass pipes 6a, 6b to by-pass exhaust gas to the upstream side of the opening and closing valves 5a, 5b from the upstream side of the filters 3a, 3b and second opening and closing valves 7a, 7b provided on an entrance of the first by-pass pipes 6a, 6b are furnished. Additionally, second by-pass pipes 8a, 8b to circulate exhaust gas passing the filters 3a, 3b in the reverse direction from the first by-pass pipes 6a, 6b on the side of the air, third opening and closing valves 9a, 9b provided on an entrance part of the second by-pass pipes 8a, 8b and a controller 10 to close the first opening and closing valves 5a, 5b at the time when an exhaust brake works and to close the first opening and closing valves 5a, 5b and to open the second and third opening and closing valves 7a, 7b, 9a, 9b at the time when the exhaust brake does not work are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate matter removing device for removing particulate matter contained in exhaust gas from a diesel engine or the like.

[0002]

2. Description of the Related Art Generally, exhaust gas from diesel engines contains a high concentration of exhaust particulates (particulates) containing soot as a main component, which causes pollution. For this reason, the exhaust system of a vehicle equipped with a diesel engine is provided with a particulate remover for removing particulates in the exhaust gas.

FIG. 4 shows an example of a conventional particulate remover. In this particulate removing device, the exhaust gas flow path from the engine is branched into two branch paths a, a, and trap filters b, b for collecting particulates are provided in each branch path a. . Backwash nozzles c, c connected to an air tank f via a solenoid valve d and a pipe e are provided on the downstream side of the trap filters b, b, and a branch is provided on the downstream side of the backwash nozzles c, c. Road a, a
Butterfly valves g, g for opening and closing the inside are provided. The butterfly valves g, g are connected to the tank f by an actuator h, a solenoid valve i and a pipe j.

During normal traveling, the exhaust gas discharged from the engine is trapped in each branch a, a trap filter b,
After passing through b, the particulates in the exhaust gas are collected, and become clean exhaust gas and flow to the downstream side (atmosphere side). During this operation, the differential pressure before and after the trap filters b, b is measured, and if the amount of particulates trapped becomes excessive and the differential pressure exceeds a predetermined value, backwashing of the filters b, b is performed.
(Playback) is performed. That is, the inside of the branch passage a is closed by the butterfly valve g, and in this state, the electromagnetic valve d is opened for a certain time. As a result, the air in the air tank f is supplied to the backwash nozzle c, and the filter b is fed from the tip of the nozzle c.
Is jetted toward. By injecting the backwash air from the backwash nozzles c, c in this way, the trap filters b, b
The particulates are peeled off and blown off to the bottom, and the filter function is regenerated.

[0005]

However, in the conventional particulate removing device, since the air in the air tank which is always equipped in the vehicle is used as the air for the above-mentioned backwash, the trap filter regeneration (reverse If you wash it frequently, a large amount of air in the tank is consumed,
There is a possibility that the air in the tank cannot be used for the original purpose, such as braking.

Therefore, the present applicant previously proposed "engine exhaust device (Japanese Patent Laid-Open No. 4-109018)" in which an electromagnetic on-off valve also serving as an exhaust brake valve is provided on the downstream side of the trap filter. According to this exhaust device, it is not necessary to use the air in the tank when the exhaust brake is actuated, so that the air consumption in the tank can be greatly reduced. However, since the air in the tank is still used when the exhaust brake is not in operation, there is a possibility that it may be difficult to secure the brake air.

An object of the present invention is to provide a particulate remover which can perform backwashing without using any air in the air tank.

[0008]

To achieve the above object, the present invention provides a trap filter provided in an exhaust gas flow path from an engine and a first on-off valve provided downstream of the trap filter. A first bypass pipe for bypassing exhaust gas from an upstream side of the filter to an upstream side of the first on-off valve, a second on-off valve provided at an inlet portion of the first bypass pipe, and the first Second bypass pipe for circulating the exhaust gas passing through the filter in the reverse direction to the atmosphere side through the bypass pipe, a third opening / closing valve provided at the inlet of the second bypass pipe, and an exhaust brake A controller that closes the first to third opening / closing valves when operating, and closes the first opening / closing valve and opens the second and third opening / closing valves when backwashing when the exhaust brake is not operating. It is a thing.

[0009]

According to the above construction, when the exhaust brake is activated, the first
The electromagnetic opening / closing valve is closed, and exhaust pulsation occurs on the upstream side of the first electromagnetic opening / closing valve, and the particulates trapped by the trap filter are removed by the pulsation.

When backwashing when the exhaust brake is not operating, the first on-off valve is closed and the second and third valves are closed.
By opening the on-off valve, the exhaust gas from the engine is introduced to the downstream side of the filter through the first bypass pipe, passes through the filter in the direction opposite to the normal time, and then passes through the second bypass pipe to the atmosphere side. Be washed away.

As described above, during normal traveling, backwashing is performed by utilizing the exhaust pulsation during the operation of the exhaust brake, and when the exhaust brake is inactive for a long period of time, the flow of the exhaust gas flowing through the filter. By performing the backwash by reversing the direction, the backwash can be performed without using the air in the air tank.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic structure of a particulate removing device. In the figure, reference numeral 1 denotes an exhaust pipe that guides exhaust gas from a diesel engine to the atmosphere side, and a branch passage 2 for branching the exhaust gas flow into the exhaust pipe 1 and joining them again.
a and 2b are formed. Branch paths 2a, 2 of the exhaust pipe 1
Trap filters 3a and 3b for collecting the particulates contained in the exhaust gas are provided at b. The trap filters 3a and 3b are made of a porous ceramic material and are housed in filter cases 4a and 4b formed in the branch paths 2a and 2b and having a substantially box shape. A large number of gas passages are formed in the trap filters 3a, 3b in the vertical direction (the direction perpendicular to the paper surface), and the case 4a,
The exhaust gas introduced into 4b is introduced into the gas passages, and then permeates laterally from the inner surface side of these gas passages and is discharged. Here, the trap filters 3a and 3b
When the exhaust gas permeates the exhaust gas, the particulates in the exhaust gas adhere to and are collected on the inner surface of the gas passage, and become the cleaned exhaust gas, which is discharged to the downstream side.

On the downstream side of the trap filters 3a, 3b, a first electromagnetic opening / closing valve 5 for opening / closing the inside of the branch passages 2a, 2b.
a and 5b are provided. These first solenoid on-off valve 5
The a and 5b perform backwashing of the filters 3a and 3b by utilizing the exhaust pulsation that occurs when the exhaust brake operates, and are also used as conventional exhaust brake valves.

First bypass pipes 6a and 6b for bypassing the filters 3a and 3b and guiding the exhaust gas are connected between the upstream and downstream sides of the trap filters 3a and 3b. The first bypass pipes 6a, 6b are adapted to appropriately discharge the exhaust gas from the engine downstream of the trap filters 3a, 3b by opening the second electromagnetic opening / closing valves 7a, 7b provided at their inlets (upstream of the opening / closing valves 5a, 5b). Side), and the exhaust gas is caused to flow in a direction opposite to the normal direction by cooperation with the solenoid opening / closing valves 5a and 5b.

Further, second bypass pipes 8a and 8b for circulating the exhaust gas passing through the filters 3a and 3b in the reverse direction to the atmosphere side are connected to the upstream sides of the trap filters 3a and 3b. ing. Here, one ends of the bypass pipes 8a and 8b are connected between the inlets of the bypass pipes 6a and 6b and the trap filters 3a and 3b, and the other ends are connected to the same positions of the other branch passages 2b and 2a, respectively.
Then, at the inlets of the second bypass pipes 8a and 8b,
Third solenoid on-off valves 9a and 9b are provided. The third electromagnetic on-off valves 9a, 9b selectively connect the branch passages 2a, 2b on the side of the filters 3a, 3b to the branch passages 2a, 2b on the upstream side thereof or the second bypass pipes 8a, 8b.

The first to third electromagnetic on-off valves 5a, 5b,
The opening and closing of 7a, 7b, 9a and 9b is controlled by the controller 10. The controller 10 is connected to the battery 12 via the key switch 11 for operating the exhaust brake, and outputs an opening / closing signal to the electromagnetic opening / closing valves 5a, 5b, 7a, 7b, 9a, 9b according to ON / OFF of the key switch 11. To do. Normally, the first solenoid on-off valves 5a and 5b are opened, the second on-off valves 7a and 7b are closed, and the third on-off valve 9 is further opened.
The a and 9b are held by connecting the filters 3a and 3b to the engine. When the key switch 11 is turned on in this state, the first electromagnetic on-off valves 5a and 5b are closed, the exhaust brake is operated, and backwashing due to exhaust pulsation is performed.
(Normal backwash mode). Also, the OF of the key switch 11
At the time of F, when the exhaust pressure from the pressure sensor (not shown) exceeds a predetermined value or the exhaust gas temperature from the temperature sensor exceeds a predetermined temperature, the first electromagnetic on-off valves 5a and 5b are closed and the second and third solenoid valves are closed. Solenoid valves 7a, 7b, 9a,
9b is opened and the direction of exhaust gas passing through the filter is reversed to perform backwashing (abnormal backwashing mode).

Next, the operation of the present embodiment configured as described above will be described.

During normal traveling, the first solenoid opening / closing valve 5
a, 5b open, the second and third on-off valves 7a, 7b, 9
a and 9b are held closed. Therefore, the exhaust gas discharged from the engine passes through the exhaust pipe 1 on the engine side and is introduced into the filter cases 4a and 4b.
When passing through the trap filters 3a and 3b in a and 4b, the particulates are collected and become clean exhaust gas, which is discharged to the atmosphere side exhaust pipe 1 via the downstream side branch passages 2a and 2b.

During normal driving, when the exhaust brake is operated as shown in FIG. 3, the trap filters 3a and 3b are backwashed in the normal backwashing mode. That is, when the key switch 11 is turned on, the controller 10 operates the first electromagnetic on-off valves 5a and 5b, and the on-off valves 5a and 5b close the flow paths in the branch passages 2a and 2b. As a result, the flow rate of the exhaust gas is limited, the braking force is applied to the vehicle, and the exhaust pulsation reciprocates between the engine and the first electromagnetic on-off valves 5a and 5b. Here, the particulates trapped in the trap filters 3a and 3b are separated from the filters 3a and 3b by the pulsating component of the exhaust gas and blown off downward, whereby clogging is prevented.

Further, when the exhaust brake is not operated for a long time such as when traveling on a highway or a long uphill, the exhaust gas temperature is first detected by the controller 10 and the exhaust gas temperature is set to a predetermined value (550 ° C.). If it exceeds, backwash in abnormal backwash mode is performed. Even if the exhaust gas temperature is less than 550 ° C, if the exhaust pressure on the upstream side of the filters 3a, 3b exceeds a predetermined value, it is determined that the particulates have increased and backwashing is performed.

In this abnormal backwash mode, backwashing is alternately performed on the trap filters 3a and 3b. For example, when backwashing the trap filter 3a, as shown in FIG. 2 (a), the inside of the branch passage 2a is closed by the first electromagnetic on-off valve 5a, and the second and third electromagnetic on-off valves 7a, 9a are closed.
open. As a result, the exhaust gas from the engine is returned to the branch passage 2a from the downstream side of the trap filter 3a through the first bypass pipe 6a. The exhaust gas returned to the branch passage 2a passes through the filter 3a in the direction opposite to the normal direction because the on-off valve 5a is closed, and at that time, particulates are separated and dropped from the filter 3a. The exhaust gas that has passed through the filter 3a is further guided to the upstream side of the other filter 3b through the second bypass pipe 8a, passes through the filter 3b, and is discharged to the downstream side.

Thereafter, when the trap filter 3b is backwashed, as shown in FIG. 2B, the first to third electromagnetic on-off valves 5a, 5b, 7a, 7b, 9a, 9b are controlled to be opened and closed as described above. Produces an exhaust gas flow similar to.

If backwashing is performed in the abnormal mode, some soot remains on the downstream side of the trap filters 3a and 3b, and is mixed with the exhaust gas and discharged when returning to the normal mode. Since the backwashing in the abnormal mode is performed only in a very limited running state, the discharge amount is minute and no problem occurs.

As described above, according to this embodiment, the backwashing is performed by utilizing the exhaust pulsation during the operation of the exhaust brake during the normal running, and the backwashing is performed by reversing the flow direction of the exhaust gas when the exhaust brake is not operated. Thus, the filters 3a and 3b can always be backwashed without using the air in the air tank as in the conventional case.

Therefore, the conventional backwash nozzle, tank, and
The air supply system such as piping can be eliminated, and the structure can be simplified and the economy can be improved. Further, it is possible to secure the amount of air in the air tank without using the air tank that is always installed in the vehicle as the air for backwashing.

In the above embodiment, the dual filter type particulate remover has been described, but it may be applied to a single filter type. In this case, the exhaust gas flowing back through the filter 3a may be circulated to the downstream side of the first electromagnetic opening / closing valve 5a by the second bypass pipe 8a. However, by adopting the dual filter type, when one filter is backwashed, the exhaust gas can be released to the atmosphere by passing the other through the filter, and the engine output reduction can be prevented.

[0028]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Since backwashing can be performed without preparing a special air source, an air supply system such as a nozzle for backwashing can be eliminated.

(2) Since the air in the air tank that is always installed in the vehicle is not used for backwashing, a sufficient amount of accumulated air in the air tank can be secured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a particulate remover of the present invention.

FIG. 2 is a diagram showing a backwash state in an abnormal backwash mode.

FIG. 3 is a flowchart showing the operation of the particulate matter removing device.

FIG. 4 is a configuration diagram showing an example of a conventional particulate matter removing device.

[Explanation of symbols]

 1 Exhaust pipe 2a, 2b Branch passage 3a, 3b Trap filter 5a, 5b 1st electromagnetic opening / closing valve 6a, 6b 1st bypass pipe 7a, 7b 2nd electromagnetic opening / closing valve 8a, 8b 2nd bypass pipe 9a, 9b Third solenoid on-off valve 10 Controller 11 Key switch

Claims (1)

[Claims] 1. A trap filter provided in an exhaust gas flow path from an engine, a first opening / closing valve provided downstream of the trap filter, and an upstream side of the filter to an upstream side of the first opening / closing valve. A first bypass pipe for bypassing the exhaust gas to the exhaust gas, a second opening / closing valve provided at the inlet of the first bypass pipe, and an exhaust gas passing through the filter in the reverse direction through the first bypass pipe. A second bypass pipe that recirculates to the atmosphere side, a third opening / closing valve provided at the inlet of the second bypass pipe, and the first to third opening / closing valves that are closed when the exhaust brake operates A particulate matter removing device comprising: a controller that closes the first on-off valve and opens the second and third on-off valves when backwashing when the brake is not operated.