JP5119470B2 - Engine exhaust gas aftertreatment device and regeneration method applied to the same - Google Patents

Description

  The present invention relates to an engine exhaust gas aftertreatment device in which at least two exhaust pipes are provided in an engine, and a filter for collecting exhaust gas is provided in each exhaust pipe, and a method for regenerating the filter in the same device It is.

(Conventional technology)
With the recent tightening of exhaust gas regulations for engines, diesel particulate filters as exhaust gas after-treatment devices are installed in the exhaust pipes of engines. In the diesel particulate filter, particulate matter (PM: particulate matter) in the exhaust gas of the engine is collected, and diffusion of PM to the atmosphere is suppressed.

However, when particulate matter PM is collected by a diesel particulate filter over a long period of time, the resistance of the flow of exhaust gas passing through the filter increases. As a result, pressure loss increases in the exhaust pipe, exhaust gas becomes difficult to exhaust, filter clogging occurs, and the function of the diesel particulate filter deteriorates. For this reason, it is necessary to regenerate the function of the diesel particulate filter by removing particulate matter PM deposited on the diesel particulate filter periodically, for example, every time the engine is operated for several tens of hours. There are various methods for regenerating such a diesel particulate filter, and one method is an “HC dosing” method.

That is, in order to remove the particulate matter PM deposited on the diesel particulate filter, it is understood that the temperature of the exhaust gas is raised and the soot in the particulate matter PM clogged with the filter is burned. ing. For this purpose, an oxidation catalyst is placed in front of the diesel particulate filter in the exhaust pipe, fuel is injected into the oxidation catalyst, and HC (hydrocarbon) in the fuel and the oxidation catalyst are oxidized to generate heat. To raise the temperature of the exhaust gas.

The HC dosing device is provided to supply fuel into the exhaust pipe for regeneration of the diesel particulate filter. In this case, the exhaust pipe is provided with a sensor for detecting the regeneration time of the filter. When it is detected by the sensor that it is time to regenerate the exhaust gas aftertreatment device, the HC dosing device supplies fuel into the exhaust pipe.

FIG. 3 shows a V-type diesel engine 10 in which cylinder rows are distributed to the left and right banks. The engine 10 is provided with exhaust pipes 11 and 12 for each of the left and right banks 10A and 10B. These two exhaust pipes 11 and 12 are respectively provided with diesel particulate filters 20 and 20.

Differential pressure detection sensors 30 and 30 are provided in the exhaust pipes 11 and 12, respectively. The differential pressure detection sensor 30 detects a differential pressure ΔP between the pressures before and after the diesel particulate filter 20. It is determined that the regeneration time has come when the differential pressure ΔP is equal to or greater than the predetermined level ΔP0. The exhaust pipes 11 and 12 are provided with HC dosing devices 40 and 40, respectively.

The controller 50 controls the HC dosing devices 40 and 40 based on detection signals from the differential pressure detection sensors 30 and 30.

As a method for regenerating the diesel particulate filters 20, 20, there is a method shown in FIG.

  That is, the control logic shown in FIG. 4 is incorporated in the controller 50 as a control program. That is, the detection signals of the two differential pressure detection sensors 30 and 30 are captured (step 101). Next, it is determined whether one of the detected values ΔP, ΔP of the two differential pressure detection sensors 30, 30 has reached the predetermined level ΔP0 first (step 102). As a result, when one of the detected values ΔP first reaches the predetermined level ΔP0, the HC dosing devices 40, 40 for the exhaust pipes 11, 12 are operated to supply fuel to the exhaust pipes 11, 12. (Step 103).

(Prior art found in patent literature)
In a V-type diesel engine in which the cylinder row is divided into left and right banks, an invention in which an exhaust pipe is provided for each of the left and right banks, and a diesel particulate filter is provided in these two exhaust pipes is disclosed in Patent Document 1 below. It is described in.

In Patent Document 2 below, two exhaust pipes communicate with each other through a communication pipe, and each exhaust pipe is located upstream of the exhaust gas position from the position where the filter is provided and upstream of the connection position of the communication pipe. An invention is described in which an HC dosing device is provided on the side. In Patent Document 2, an exhaust control valve is provided in the exhaust pipe.
JP 2007-71141 A Japanese Patent Laid-Open No. 2007-120552

  In the regeneration method shown in FIG. 4, when the detected value ΔP reaches the predetermined level ΔP0 first of the two differential pressure detection sensors 30, 30, fuel is supplied to both the exhaust pipes 11, 12 simultaneously. Therefore, excessive fuel is supplied to the exhaust pipe whose detected value ΔP has not reached the predetermined level ΔP0. For this reason, there is a problem that fuel is wasted.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine exhaust gas aftertreatment device and a regeneration method thereof in which fuel is not wasted.

The first invention is
An exhaust gas aftertreatment device for an engine in which at least two exhaust pipes are provided in the engine, and a filter for collecting particulate matter in the exhaust gas is provided in each exhaust pipe,
Each exhaust pipe is connected to a communication pipe that communicates the exhaust pipes with each other on the exhaust upstream side of the position where the filter is disposed.
HC dosing for supplying HC (hydrocarbon) into the exhaust pipe for regeneration of the filter, for each exhaust pipe, upstream of the position where the filter is disposed and downstream of the position where the communication pipe is connected. Equipment is provided,
A sensor for detecting the regeneration time of the filter is provided in at least one of the exhaust pipes.

The second invention is
A regeneration method in which at least two exhaust pipes are provided in an engine, and a filter that collects particulate matter in the exhaust gas is applied to an exhaust gas aftertreatment device of the engine provided in each exhaust pipe,
Causing a difference in resistance between the exhaust pipes in the flow of exhaust gas passing through the filter, thereby generating a flow of exhaust gas from the exhaust pipe having a high resistance toward the exhaust pipe having a low resistance;
Detecting that at least one of the exhaust pipe filters is in a regeneration period;
And regenerating the filter by supplying HC (hydrocarbon) into each exhaust pipe when it is detected that the regeneration time has come.

  In the first invention, as shown in FIG. 1, at least two exhaust pipes 11, 12 are provided in the engine 10, and filters 20, 20 that collect particulate matter in the exhaust gas are provided in the exhaust pipes 11, 12. The exhaust gas aftertreatment device 60 of the engine 10 provided is assumed.

A communication pipe 61 that connects the exhaust pipes 11 and 12 to each other is connected to the exhaust pipes 11 and 12 on the upstream side of the exhaust gas from the position where the filter 20 is disposed.

  For each of the exhaust pipes 11 and 12, the exhaust pipe is upstream of the position where the filter 20 is disposed and is further downstream of the exhaust pipe than the connection position of the communication pipe 61. HC dosing devices 40 and 40 for supplying HC (hydrocarbon) are provided.

  A sensor 30 for detecting the regeneration timing of the filter 20 is provided in any one exhaust pipe, for example, the exhaust pipe 11.

  The amount of particulate matter in the exhaust gas flowing through the exhaust pipes 11 and 12 is not necessarily equal. For this reason, the collection amount of the filter 20 in one exhaust pipe 11 and the filter 20 in the other exhaust pipe 12 is not necessarily equal, and there is a resistance difference in the flow of exhaust gas passing through the filters 20, 20. , 12 occurs.

  When a difference in resistance occurs between the exhaust pipes 11 and 12 in the flow of exhaust gas passing through the filters 20 and 20, an exhaust pipe having high resistance, for example, an exhaust pipe having low resistance from the exhaust pipe 11 is connected via the communication pipe 61. An exhaust gas flow toward 12 is generated. As a result, the amount of exhaust gas flowing through the filter 20 of the exhaust pipe 11 having high resistance decreases, and the amount of exhaust gas flowing through the filter 20 of the exhaust pipe 12 having low resistance increases, thereby collecting the filter 20 in the exhaust pipe 11. The increase rate of the amount decreases, and the increase rate of the collection amount of the filter 20 of the exhaust pipe 12 increases. Thereby, the resistance of the flow which passes through each exhaust pipe 11 and 12 becomes equal (step 301 of FIG. 2).

  Eventually, it is detected that the filter 20 of at least one of the exhaust pipes 11 has reached the regeneration time (step 302 in FIG. 2).

When it is detected that the regeneration time has come, HC (hydrocarbon), specifically, fuel is supplied into the exhaust pipes 11 and 12. As a result, the filter 20 is regenerated (step 303 in FIG. 2).

According to the present invention, in the state where the collected amounts of the filters 20 and 20 of the exhaust pipes 11 and 12 are equal, both reach the regeneration time at the same time, and the fuel of the exhaust pipes 11 and 12 is supplied. Fuel is not wasted.

Further, since the collected amounts of the filters 20 and 20 of the exhaust pipes 11 and 12 are equalized, if at least one of the exhaust pipes 11 is represented, a sensor 30 for detecting the regeneration timing is provided. Good. Thereby, the minimum required number of sensors 30 for detecting the reproduction time can be reduced. Of course, two sensors 30 can be provided in consideration of sensor failure or the like.

  In Patent Document 2, an HC dosing device is provided on the exhaust upstream side of the position where the filter is provided and on the exhaust upstream side of the connection position of the communication pipe, and the fuel injected from the HC dosing device. May adhere to the communication pipe and may become a useless fuel that does not contribute to regeneration. In the present invention, since the HC dosing device 40 is provided on the exhaust upstream side with respect to the arrangement position of the filter 20 and on the exhaust downstream side with respect to the connection position of the communication pipe 61, the fuel is wasted in this way. There is no fear.

  Hereinafter, embodiments of an exhaust gas aftertreatment device for an engine and a regeneration method applied to the device according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration diagram of an exhaust gas aftertreatment device 60 of the engine 10 of the embodiment.

As shown in FIG. 1, the engine 10 is a V-type diesel engine in which the cylinder row is distributed to the left and right banks 10A and 10B. The exhaust pipe 11 is provided for each of the left and right banks 10A and 10B of the engine 10. , 12 are provided. Diesel particulate filters 20 and 20 are provided inside the two exhaust pipes 11 and 12, respectively. The diesel particulate filter 20 collects particulate matter in the exhaust gas.

A communication pipe 61 that connects the exhaust pipes 11 and 12 to each other is connected to the exhaust pipes 11 and 12. The communication pipe 61 is connected to the exhaust pipes 11 and 12 at a position on the exhaust upstream side of the position where the diesel particulate filter 20 is disposed. A turbo (not shown) is provided between the communication pipe 61 and an exhaust manifold (not shown) of the engine 10.

  For each of the exhaust pipes 11 and 12, the regeneration of the diesel particulate filter 20 is at a position upstream of the exhaust gas from the position where the diesel particulate filter 20 is disposed and downstream of the connection position of the communication pipe 61. Therefore, HC dosing devices 40 and 40 for supplying fuel as HC (hydrocarbon) are provided in the exhaust pipes 11 and 12. A sensor 30 for detecting the regeneration timing of the diesel particulate filter 20 is provided in any one exhaust pipe, for example, the exhaust pipe 11. This sensor 30 is a differential pressure detection sensor 30 and detects a differential pressure ΔP between pressures before and after the diesel particulate filter 20. It is determined that the regeneration time has come when the differential pressure ΔP is equal to or greater than the predetermined level ΔP0. The controller 50 controls the HC dosing devices 40 and 40 based on the detection signal of the differential pressure detection sensor 30.

Based on the detection signal from the differential pressure detection sensor 30, the controller 50 determines that it is time to regenerate the diesel particulate filter 20, and at that time, instructs the fuel supply into the exhaust pipes 11, 12. The HC dosing pump (not shown) and each control valve provided in the fuel supply path between the fuel injection nozzle (not shown) and the HC dosing pump are applied. As a result, the HC dosing pump is activated and each control valve is opened. When the HC dosing pump 16 operates, fuel (light oil) in a fuel tank (not shown) is sucked into the suction port of the HC dosing pump. The HC dosing pump pressurizes and discharges fuel to a predetermined fuel pressure suitable for supply into the exhaust pipes 11 and 12, for example, about 7 to 10 kgf / cm 2. The fuel boosted by the HC dosing pump is supplied to each control valve,
It is injected and supplied into the exhaust pipes 11 and 12 through the combustion injection nozzle.

  FIG. 2 is a flowchart showing the flow of processing performed in the embodiment. Step 301 in FIG. 2 shows the operation by the communication pipe 61, and steps 302 and 303 in FIG. 2 show processing performed by the controller 50.

  The amount of particulate matter in the exhaust gas flowing through the exhaust pipes 11 and 12 is not necessarily equal. For this reason, the collected amount of the diesel particulate filter 20 in the one exhaust pipe 11 and the diesel particulate filter 20 in the other exhaust pipe 12 are not necessarily equal, and the exhaust gas passing through the diesel particulate filters 20, 20 is not uniform. A resistance difference in flow occurs between the exhaust pipes 11 and 12.

  A resistance difference in the flow of exhaust gas passing through the diesel particulate filters 20, 20 occurs between the exhaust pipes 11, 12. An exhaust gas flow toward the small exhaust pipe 12 occurs. As a result, the amount of exhaust gas flowing through the diesel particulate filter 20 of the exhaust pipe 11 having a high resistance is reduced, and the amount of exhaust gas flowing through the diesel particulate filter 20 of the exhaust pipe 12 having a low resistance is increased. The increase rate of the collected amount of the diesel particulate filter 20 is reduced, and the increase rate of the collected amount of the diesel particulate filter 20 of the exhaust pipe 12 is increased. Thereby, the resistance of the flow which passes through each exhaust pipe 11 and 12 becomes equal (step 301).

  The exhaust gas discharged from one bank 10A of the engine 10 is always branched by the communication pipe 61 and simultaneously has two flows, that is, a flow toward the particulate filter 20 of the exhaust pipe 11 and the communication pipe 61. A flow toward the particulate filter 20 of the other exhaust pipe 12 is formed. Similarly, the exhaust gas discharged from one bank 10B of the engine 10 is always branched by the communication pipe 61 and simultaneously flows into two flows, that is, the flow toward the particulate filter 20 of the exhaust pipe 12 and the communication pipe 61. Thus, a flow toward the particulate filter 20 of the other exhaust pipe 11 is formed.

  Eventually, the differential pressure detection value ΔP of the differential pressure detection sensor 30 provided in any one of the exhaust pipes 11 reaches a predetermined level ΔP0, and the diesel particulate filter 20 of any one of the exhaust pipes 11 has reached the regeneration time. Determination is made (YES at step 302). At this time, the diesel particulate filter 20 of the other exhaust pipe 12 is also considered to be in the regeneration period, and the HC dosing devices 40 and 40 are simultaneously operated, and HC (hydrocarbon) is placed in the exhaust pipes 11 and 12. Specifically, fuel is supplied. Thereby, the diesel particulate filters 20 and 20 of the exhaust pipes 11 and 12 are regenerated (step 303).

According to the present embodiment, in the state where the collection amounts of the diesel particulate filters 20, 20 in the exhaust pipes 11, 12 are equal, both reach the regeneration time at the same time, and the exhaust pipes 11, 12 Since fuel is supplied, fuel is not wasted.

In addition, since the collection amounts of the diesel particulate filters 20 and 20 in the exhaust pipes 11 and 12 are equalized, a sensor 30 for detecting the regeneration timing is provided by representing one of the exhaust pipes 11. Just do it. Thereby, the minimum required number of sensors 30 for detecting the reproduction time can be reduced. Of course, in consideration of sensor failure or the like, one sensor 30 may be provided for each of the exhaust pipes 11 and 12, and two sensors 30 may be provided in total.

Further, as shown in FIG. 2, since it is only necessary to determine the regeneration time based on the detection signal of one sensor 30 and control the HC dosing devices 40 and 40 to operate simultaneously, at least one control logic is also required. (Fig. 2). Thereby, the configuration of the controller 50 can be simplified.

  By the way, the non-combustible metal component mainly in the lubricating oil is gradually deposited on the diesel particulate filter 20 as ash. When the amount of accumulated ash reaches the limit, the diesel particulate filter 20 needs to be cleaned or replaced.

In this case, similarly to the regeneration method of the diesel particulate filter 20, a method in which the exhaust pipes 11 and 12 are individually cleaned or replaced, and an ash accumulation amount in any of the exhaust pipes 11 and 12. It is conceivable to perform cleaning or replacement at the same time when the amount reaches the limit amount. However, both methods are costly.

According to the present embodiment, the amount of ash deposited is equalized by the diesel particulate filters 20 and 20 of the exhaust pipes 11 and 12 as well as the amount of particulate matter collected in the exhaust gas. For this reason, when it is determined that the amount of accumulated ash in one of the exhaust pipes, for example, the exhaust pipe 11, has reached the limit amount, the diesel particulate filters 20, 20 of both the exhaust pipes 11, 12 are simultaneously cleaned or replaced. By doing so, wasteful expenses can be reduced.

In the embodiment, it is assumed that the engine 10 is provided with two exhaust pipes 11 and 12. However, the present invention only requires that at least two exhaust pipes be provided, and that three or more exhaust pipes be provided. It can be applied to an engine provided with a pipe.

  The present invention can also be applied to an apparatus configuration in which an oxidation catalyst is disposed upstream of the diesel particulate filter 20 provided in each of the exhaust pipes 11 and 12 to process exhaust gas.

FIG. 1 is a configuration diagram of an exhaust gas aftertreatment device for an engine according to an embodiment. FIG. 2 is a flowchart showing the flow of processing in the embodiment. FIG. 3 is a diagram used for explaining the prior art. FIG. 4 is a diagram for explaining a conventional reproduction method.

Explanation of symbols

10 engine, 11, 12 exhaust pipe, 20 filter (diesel particulate filter), 30 sensor (differential pressure sensor), 40 HC dosing device, 50 controller, 260 exhaust gas aftertreatment device, 61 communication pipe

Claims (1)

An exhaust gas aftertreatment device for an engine in which at least two exhaust pipes are provided in the engine, and a filter for collecting particulate matter in the exhaust gas is provided in each exhaust pipe,
Each exhaust pipe is connected to a communication pipe that communicates the exhaust pipes with each other on the exhaust upstream side of the position where the filter is disposed.
HC dosing for supplying HC (hydrocarbon) into the exhaust pipe for regeneration of the filter, for each exhaust pipe, upstream of the position where the filter is disposed and downstream of the position where the communication pipe is connected. Equipment is provided,
At least one of the exhaust pipes is provided with a sensor for detecting the regeneration time of the filter,
While the exhaust gas is being exhausted from the engine, the exhaust pipes are always in communication with each other via the communication pipe, and the exhaust gas from the engine to the filter is in all exhaust pipes . It is in a state where a flow is formed,
When the regeneration time of the filter is detected by the sensor, it is determined that all the filters provided in the exhaust pipes have reached the regeneration time, and the HC dosing device is operated for all the exhaust pipes. An exhaust gas aftertreatment device for an engine, wherein control for supplying the HC into the exhaust pipe of the engine is performed.

Images