JP5656280B2 - Post-treatment fuel addition equipment - Google Patents

Description

  In the present invention, when forcibly regenerating a filter (DPF) that collects harmful particulate components in exhaust gas flowing through an exhaust system of an internal combustion engine in an automobile, fuel is added to the exhaust system in order to increase the temperature of the DPF. The present invention relates to a processing fuel addition apparatus.

In an internal combustion engine (diesel engine) having such an aftertreatment fuel addition device, when the DPF interposed in the exhaust system is forcibly regenerated, fuel is added from the aftertreatment fuel addition device to the exhaust system, The DPF is regenerated by increasing the temperature.
Here, when the soot adheres to the piping of the post-processing fuel addition device, particularly the piping communicating with the exhaust system of the internal combustion engine, the flow passage cross-sectional area of the piping of the post-processing fuel addition device decreases.
The reduction in the flow passage cross-sectional area of the pipe hinders the supply of post-processing fuel, and the forced regeneration of the DPF is not performed properly.

In the prior art, high-pressure air is injected into the piping of the post-processing fuel addition device for a predetermined time at regular intervals during which the internal combustion engine is operating, so that the soot accumulated in the piping is removed.
In recent years, an increase in consumption of compressed air accompanying measures for improving brake performance and an increase in demand for high-pressure air as a power source for various devices have become prominent. If the consumption of high-pressure air increases, the compressor that generates high-pressure air frequently operates. If the compressor is operated frequently, the horsepower consumed by the internal combustion engine increases, resulting in a deterioration in fuel consumption and consequently an increase in CO ₂ emissions. From this point of view, it is desirable to suppress the consumption of high-pressure air as much as possible, thereby reducing CO ₂ emissions.
However, in order to remove the soot accumulated in the pipe, frequently injecting the high-pressure air into the pipe goes against suppressing the consumption of the high-pressure air and reducing the CO ₂ emission amount.

As another conventional technique, a technique for preventing the exhaust gas flowing through the exhaust pipe from being clogged with soot has been proposed (see Patent Document 1).
However, the related art (Patent Document 1) is intended to accurately measure the pressure of the exhaust gas, and as described above, prevents soot from adhering to the piping of the post-treatment fuel addition device. is not.

JP 2002-257664 A

  The present invention has been proposed in view of the above-described problems of the prior art, and can reduce the amount of soot accumulated in the piping and can reduce the consumption of compressed air. The purpose of this is to provide a fuel addition device.

An aftertreatment fuel addition device (100) according to the present invention includes an air supply system in an internal combustion engine exhaust system (3) between an internal combustion engine (1) and a filter (2) that collects harmful particulate components in exhaust gas. In the post-processing fuel addition device having a post-processing fuel injection mechanism (4) for supplying high pressure air from (La) and fuel from the fuel supply system (Lf) from the nozzle (5), the fuel supply system ( Lf) is connected from the fuel supply source to the junction (G) of the air supply system (La) via the first on-off valve (Vf1) and the second on-off valve (Vf2). (La) is connected from the fuel supply source to the junction (G) via the third on-off valve (Va), and the junction (G) is connected to the nozzle (5) via the line (Lg). Connected to the first on-off valve (Vf1) and the second on-off valve. A first measuring device (43) for measuring the pressure (Pa) inside the fuel supply system (Lf) between (Vf2), the upstream side of the filter (2) and the downstream side or the large side of the filter (2) Based on the measurement results from the second measuring device (6, 60) that measures the differential pressure from the atmospheric pressure, the first measuring device (43), and the second measuring device, the first and second And a control device (10) for opening and closing the third on-off valve (Vf1, Vf2, Va). The control device (10) measures the pressure (Pe) of the internal combustion engine exhaust system (3). Filter for collecting harmful particulate components in the exhaust gas flowing through the exhaust system (3) of the internal combustion engine (3) based on the measurement results from the measurement devices (6, 60) and the measurement result of the first measurement device (43) When the DPF 2) is not forcibly regenerated, the internal pressure of the fuel supply system (Lf) (Pa) is characterized by having a function of controlling so as to be pressure (Pe) or an internal combustion engine exhaust system (3).

In the present invention, when the control device (10) does not forcibly regenerate the filter (DPF2) that collects harmful particulate components in the exhaust gas flowing through the exhaust system (3), the post-treatment fuel injection is performed. The third on- off valve (air purge valve Va) is PWM controlled (valve on / off) so that the internal pressure (Pa) of the mechanism 4 is equal to or higher than the pressure (Pe) of the internal combustion engine exhaust system (3). It is preferable to have a function of controlling the time for turning on and the time for turning off as appropriate.

In the present invention, the control device (10) does not forcibly regenerate the filter (DPF2) for collecting harmful particulate components in the exhaust gas flowing through the internal combustion engine exhaust system (3), and the internal combustion engine exhaust system. When the pressure (Pe) in (3) is larger than the threshold value, the second opening / closing valve (Vf2) of the fuel supply system (Lf) is closed, and the third opening / closing of the air supply system (La) is performed . It is preferable to have a function of keeping the valve (air purge valve Va) open.

  In the present invention, when the control device (10) forcibly regenerates the filter (DPF2) that collects harmful particulate components in the exhaust gas flowing through the exhaust system (3), the control device (10) of the fuel supply system (Lf) The first on-off valve (fuel cutoff valve Vf1) and the second on-off valve (diesel dosing valve Vf2) are opened to supply fuel to the internal combustion engine exhaust system (3). Is preferred.

Furthermore, in the present invention, the control device (10) includes a first fuel supply system (Lf) for a predetermined period (set on a case-by-case basis) after the internal combustion engine (1) is stopped. The on-off valve (fuel cutoff valve Vf1) and the second on-off valve (diesel dosing valve Vf2) are closed, and the third on- off valve (air purge valve Va) of the air supply system (La) is opened. It preferably has a function of opening.

In addition, in the present invention, when an abnormality occurs, the control device (10) includes a third on- off valve (air purge valve: Va) of the air supply system (La), a fuel supply system. It is preferable to have a function of closing the first on-off valve (fuel cut-off valve Vf1) and the second on-off valve (diesel dosing valve Vf2) of (Lf).

In the present invention, the measuring device for measuring the pressure of the internal combustion engine exhaust system (3) is an upstream side (internal combustion engine side) of a filter (DPF2) that collects harmful particulate components in the exhaust gas flowing through the exhaust system (3). It is preferable to comprise a differential pressure sensor (6) that measures the differential pressure between the pressure and the downstream (atmosphere side) pressure.
Alternatively, the measuring device for measuring the pressure of the internal combustion engine exhaust system (3) is an upstream side (internal combustion engine side) of a filter (DPF: 2) that collects harmful particulate components in the exhaust gas flowing through the exhaust system (3). It is preferable to comprise a differential pressure sensor (60) that measures a differential pressure between the pressure and the atmospheric pressure.
Here, the upstream side (internal combustion engine side) pressure of the filter (DPF2) for collecting harmful particulate components in the exhaust gas flowing through the exhaust system (3) is the internal pressure (Pa) of the post-processing fuel injection mechanism (4). )be equivalent to.

According to the present invention having the above-described configuration, the control device (10) includes the measurement result from the measurement device (6) that measures the pressure (Pe) of the internal combustion engine exhaust system (3) and the internal pressure measurement device (43). ), When the filter (DPF2) for collecting harmful particulate components in the exhaust gas flowing through the exhaust system (3) is not forcibly regenerated, the internal pressure (of the fuel supply system Lf) ( Since Pa) is controlled to be equal to or higher than the pressure (Pe) of the internal combustion engine exhaust system (3), the exhaust including soot flowing through the exhaust system (3) has a pressure equal to or higher than the exhaust system (3). Intrusion into the aftertreatment fuel injection mechanism (4) is prevented. Therefore, the accumulation amount of soot in the piping (supply line Lg) inside the post-processing fuel injection mechanism (4) is reduced.
As a result, when forcibly regenerating the filter (DPF: 2) that collects harmful particulate components in the exhaust gas flowing through the exhaust system (3), the target amount of fuel required for forced regeneration from the fuel supply system (Lf) is obtained. Is reliably supplied to the internal combustion engine exhaust system (3).

Here, the pressure (Pa) inside the aftertreatment fuel injection mechanism (4) (in the aftertreatment fuel addition device 100) may be equal to or higher than the pressure (Pe) of the internal combustion engine exhaust system (3). Compared to the pressure (Pe) of the engine exhaust system (3), it is not necessary to make it extremely high.
Therefore, the amount of pressurized air leaking to the exhaust system (3) is small, and there is no possibility that the pressurized air is wasted.

In the present invention, when the pressure (Pe) of the internal combustion engine exhaust system (3) rises above a threshold value, the control device (10) opens and closes the open / close valve (air purge valve) of the air supply system (La). : If Va has a function of maintaining the open state, the pressure (Pa) of the post-processing fuel injection mechanism (4) is also maintained at a high pressure.
Therefore, even if the pressure (Pe) of the exhaust system (3) increases, the state in which the amount of accumulated soot in the piping (particularly the line Lg) of the post-processing fuel injection mechanism (4) is reduced is maintained.

  In the present invention, when the filter (DPF2) for collecting harmful particulate components in the exhaust gas flowing through the exhaust system (3) is forcibly regenerated, the first open / close valve (fuel cut) of the fuel supply system (Lf) is used. If the off valve Vf1) and the second on-off valve (diesel dosing valve Vf2) are opened and fuel is supplied to the internal combustion engine exhaust system (3), the fuel is oxidized by the oxidation catalyst, and the DPF (2) The temperature rises and soot burns. Then, the regeneration operation is performed satisfactorily.

Further, in the present invention, the first on-off valve (fuel cut-off valve Vf1) of the fuel supply system (Lf) for a predetermined period (set on a case-by-case basis) after the internal combustion engine (1) is stopped. ) And the second on-off valve (diesel dosing valve Vf2), and the operation to open the on-off valve (air purge valve Va) of the air supply system (La) is performed. If the open / close valve (air purge valve Va) of the air supply system (La) is opened, the soot accumulated in the supply system (Lg) is easily removed.
Since the internal combustion engine (1) is stopped, the pressure (Pe) of the exhaust system (3) is reduced, and the pipe (particularly the line Lg) of the post-processing fuel injection mechanism (4) is also raised immediately after operation. This is because the soot that has been heated and the soot adhering thereto is also heated to be easily removed.

It is a block diagram which shows the structure of the fuel addition apparatus for post-processing which concerns on embodiment. It is a block diagram which shows the fuel injection mechanism for post-processing in the fuel addition apparatus for post-processing which concerns on embodiment. It is a flowchart which shows the fuel addition procedure which concerns on embodiment. It is a block diagram which shows the modification of embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, the post-processing fuel addition device generally indicated by reference numeral 100 includes a post-processing fuel injection mechanism 4, a nozzle 5, an exhaust system pressure sensor 6, and a control device 10.
Here, the post-processing fuel injection mechanism 4 has a function of injecting fuel into the exhaust system when the DPF is regenerated, and is a device constituting a so-called “injector”.

In the illustrated embodiment, the aftertreatment fuel addition apparatus 100 is a diesel engine in which an exhaust pipe 3 is provided with a filter (hereinafter referred to as “DPF”) 2 that collects harmful particulate components in engine exhaust gas. It is applied to an engine (hereinafter referred to as “engine”) 1.
The exhaust system pressure sensor 6 detects the exhaust gas pressure (differential pressure) before and after the DPF 2 in the exhaust pipe 3 by lines 7 and 8.
The nozzle 5 opens its injection hole 5 h in a region between the engine 1 and the DPF 2 in the exhaust pipe 3, and air or fuel supplied from the post-processing fuel injection mechanism 4 is supplied to the DPF 2 in the exhaust pipe 3. It is configured to inject upstream.

In FIG. 2, the post-processing fuel injection mechanism 4 includes a compressed air supply line La and a fuel supply line Lf.
The compressed air supply line La communicates the high-pressure air supply source and the confluence G with an open / close valve (air purge valve) Va on the high-pressure air supply source side and a check valve on the confluence point G side. 41 is interposed.
The junction G and the nozzle 5 are connected by a line Lg. Here, the line Lg is a pipe (line) in which soot accumulates most among the pipes in the post-processing fuel injection mechanism 4.

The fuel supply line Lf communicates the fuel supply source with the junction G, and includes a first opening / closing valve (fuel cutoff valve) Vf1 on the fuel supply source side, and a second opening / closing valve on the junction G side. (Diesel dosing valve) Vf2 is installed. In the fuel supply line Lf, a check valve 42 is interposed on the first opening / closing valve Vf1 side in the region between the first opening / closing valve Vf1 and the second opening / closing valve Vf2. A pressure sensor 43 is provided on the valve Vf2 side.
Here, if the second opening / closing valve Vf <b> 2 is opened, the pressure measured by the pressure sensor 43 becomes the internal pressure of the post-processing fuel injection mechanism 4.

  The on-off valve (air purge valve) Va, the first on-off valve (fuel cut-off valve) Vf1, and the second on-off valve (diesel dosing valve) Vf2 are all electromagnetic on-off valves. (See FIG. 1) and a control signal line Lso. Further, the pressure sensor 43 and the exhaust system pressure sensor 6 are connected to the control device 10 by an input signal line Lsi.

When the control device 10 does not forcibly regenerate the DPF 2 based on the measurement result (differential pressure) of the exhaust system pressure sensor 6 and the measurement result (Pa) of the pressure sensor 43 in the post-processing fuel injection mechanism 4. Opens the second on-off valve Vf2 of the fuel supply line Lf. Thereby, the pressure measured by the sensor 43 is made equal to the internal pressure of the post-processing fuel injection mechanism 4.
Then, the open / close valve Va of the compressed air supply line La is controlled so that the pressure Pa in the post-processing fuel injection mechanism 4 is the pressure Pe of the exhaust pipe 3 (in the illustrated embodiment, a sensor that directly measures the exhaust pipe pressure Pe). (Not shown): The pressure Pe in the exhaust pipe 3 is specified by the sum of the differential pressure measured by the sensors 6 and 60 and other pressures. By setting the pressure Pa in the aftertreatment fuel injection mechanism 4 to be equal to or higher than the pressure Pe of the exhaust pipe 3, the exhaust gas is prevented from flowing back to the aftertreatment fuel injection mechanism 4 side, and soot is not accumulated in the line Lg. Because.

For controlling the open / close valve Va of the compressed air supply line La when the DPF 2 is not forcibly regenerated, for example, the pressure (Pa) in the post-processing fuel injection mechanism 4 slightly reduces the pressure (Pe) in the exhaust pipe 3. The open / close valve Va is PWM controlled so as to exceed this.
Here, the PWM control is on / off control of the valve, and is control in which the time for turning on and the time for turning off are appropriately set.
By performing PWM control of the on-off valve Va, the pressure Pa in the post-processing fuel injection mechanism 4 does not become higher than necessary (for example, much higher than the pressure Pe of the exhaust pipe 3). This is because the pressure Pa in the post-processing fuel injection mechanism 4 is slightly higher than the exhaust pipe pressure Pe to suppress the consumption of compressed air.

When the DPF 2 is not forcibly regenerated and the pressure (Pe) of the exhaust pipe 3 is larger than the threshold value, the control device 10 closes the second on-off valve Vf2 to open the on-off valve. It has a function of keeping Va open.
This is because the pressure Pa in the post-processing fuel injection mechanism 4 is maintained at a high pressure and the volume of soot in the line Lg is reduced by opening the on-off valve Va. Then, by closing the second opening / closing valve Vf2, the high pressure on the compressed air supply line La side (generated by opening the opening / closing valve Va) is prevented from escaping to the fuel supply line Lf side.

When the DPF 2 is forcibly regenerated, the control device 10 opens the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf, and supplies fuel to the exhaust pipe 3 to the exhaust pipe 3. It has a function to do.
This is because the fuel necessary for the forced regeneration of the DPF 2 is reliably supplied from the post-processing fuel injection mechanism 4 to the exhaust pipe 3 side.

Further, the control device 10 includes the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf for a predetermined period (set on a case-by-case basis) after the engine 1 is stopped. And the open / close valve Va of the compressed air supply line La is opened.
Since the engine 1 is stopped, the pressure Pe of the exhaust pipe 3 is reduced, and immediately after the engine 1 is stopped, the line Lg of the post-processing fuel injection mechanism 4 is also heated. The temperature also rises and it is easy to remove the soot. By opening the open / close valve Va of the compressed air supply line La in this state, the soot accumulated in the line Lg can be discharged to the exhaust pipe 3 side by the compressed air.

In addition, when any abnormality occurs, the control device 10 closes the opening / closing valve Va of the compressed air supply line La, the first opening / closing valve Vf1 and the second opening / closing valve Vf2 of the fuel supply line. It has a function.
This is because by closing all the valves in the post-processing fuel injection mechanism 4 at the time of abnormality, the abnormality chain is prevented and the situation where abnormality occurs to the fuel supply source and the compressed air source does not occur. .

Next, based on the flowchart of FIG. 3, the operation procedure of the post-processing fuel addition apparatus 100 in the embodiment will be described.
In step S1 of FIG. 3, the control device 10 determines whether or not the key switch is ON.
If the key switch is ON (step S1 is YES), the process proceeds to step S2.

On the other hand, if the key switch is turned OFF at the end of operation (NO in step S1), the process proceeds to step S6, and the post-processing fuel injection mechanism 4 is switched to the after-run air purge mode. In order to perform the after-run air purge, the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf are closed, and the on-off valve Va of the compressed air supply line La is opened for a predetermined time (step S7).
At this time, since the engine 1 is stopped, the exhaust pressure Pe of the exhaust pipe 3 is decreased. Immediately after the operation, the supply system (Lg) also rises in temperature, soot accumulated in the line Lg also rises in temperature, and the soot is easily peeled off from the line Lg. Therefore, when compressed air is supplied from the compressed air supply line La, the soot accumulated in the line Lg easily peels from the tube wall of the line Lg and is discharged to the exhaust pipe 3 side through the nozzle 5.
In step S7, it is determined whether or not a predetermined time has elapsed, that is, whether or not an after-run air purge has been performed for a predetermined time. If the after-run air purge is performed for a predetermined time, the process returns to step S1.

In step S2, the control device 10 determines whether or not the addition by the post-processing fuel injection mechanism 4 is performed, that is, whether or not the DPF 2 is forcibly regenerated.
If fuel is not added by the post-processing fuel injection mechanism 4 (inoperative), that is, if the DPF 2 is not forcibly regenerated (YES in step S2), the process proceeds to step S3.

On the other hand, if fuel is added by the post-processing fuel injection mechanism 4 (operation), that is, if the DPF 2 is forcibly regenerated (NO in step S2), the process proceeds to step S8, where the post-processing fuel injection mechanism 4 The fuel addition mode is executed.
In the fuel addition mode (step S8) by the post-processing fuel injection mechanism 4, both the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf are opened (step S9). When the first on-off valve Vf1 and the second on-off valve Vf2 are opened, the fuel is injected from the nozzle 6 into the exhaust pipe 3, the fuel is oxidized, and the soot accumulated in the DPF 2 is combusted (forced DPF 2) Regeneration).
If the first on-off valve Vf1 and the second on-off valve Vf2 are opened for a predetermined time and the DPF 2 is forcibly regenerated for a necessary time, the process returns to step S1.
In step S9, during fuel addition, the on-off valve Va is closed and no air is supplied. Air may be appropriately supplied before and after fuel addition.

In step S3, the control device 10 determines whether or not the differential pressure Pe of the DPF 2 measured by the exhaust system pressure sensor 6 is equal to or lower than a threshold value, that is, compared with the pressure in the post-processing fuel injection mechanism 4. It is determined whether or not the pressure is higher than a predetermined value.
If the exhaust pressure is not high and the differential pressure Pe of the DPF 2 is equal to or less than the threshold (YES in step S3), the risk of exhaust gas flowing back from the exhaust pipe 3 into the aftertreatment fuel injection mechanism 4 is not high. Determine and proceed to step S4.
On the other hand, if the differential pressure Pe of the DPF 2 exceeds the threshold value, that is, if the exhaust pressure in the exhaust pipe 3 is high (NO in step S3), the post-processing fuel is used to counter the high pressure in the exhaust pipe 3. The injection mechanism 4 is switched to the fully open purge mode (step S10). Accordingly, in order to prevent exhaust gas from flowing back to the post-processing fuel injection mechanism 4 and soot in the exhaust gas from adhering to the piping in the post-processing fuel injection mechanism 4, the process proceeds to step S11. move on.

In order to switch the post-processing fuel injection mechanism 4 to the fully opened purge mode, in step S11, the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf are closed, and the on-off valve of the compressed air supply line La is closed. Va is released.
By opening the open / close valve Va of the compressed air supply line La, the pressure Pa in the post-processing fuel injection mechanism 4 becomes high, and even if the pressure Pe of the exhaust pipe 3 rises, the pressure in the exhaust pipe 3 is reduced. It is prevented that the soot accumulates in the supply line Lg by flowing into the processing fuel injection mechanism 4 side.
Further, by closing the second opening / closing valve Vf2 of the fuel supply line Lf, the high pressure obtained by opening the opening / closing valve Va is prevented from escaping to the fuel supply line Lf side.
After step S11, the process returns to step S1, and step S1 and subsequent steps are repeated.

Next, steps S4 and S5 will be described. In steps S4 and S5, the mode is switched to the purge pressure control mode, and the pressure in the post-processing fuel injection mechanism 4 is maintained to be equal to or higher than the exhaust pressure in the exhaust pipe 3.
Here, while the engine 1 is operating, the differential pressure of the DPF 2 is measured by the pressure sensor 6 of the exhaust system. On the other hand, if the second opening / closing valve Vf2 is opened, the pressure measured by the pressure sensor 43 can be regarded as the internal pressure of the post-processing fuel injection mechanism 4.

In step S5, the second open / close valve Vf2 of the fuel supply line Lf is opened so that the pressure Pa, which is a measurement value of the pressure sensor 43, can be regarded as the pressure in the post-processing fuel injection mechanism 4. . The exhaust pressure in the exhaust pipe 3 is obtained by adding the differential pressure measured by the exhaust system pressure sensor 6 to the atmospheric pressure.
In step S5, the pressure Pa measured by the pressure sensor 43 (the pressure regarded as the pressure in the post-processing fuel injection mechanism 4) and the exhaust pressure of the exhaust pipe 3 (the differential pressure and the atmospheric pressure measured by the pressure sensor 6). The pressure Pa regarded as the pressure in the post-processing fuel injection mechanism 4 is equal to or higher than the exhaust pressure of the exhaust pipe 3 (the sum of the differential pressure measured by the pressure sensor 6 and the atmospheric pressure). Similarly, the open / close valve Va of the compressed air supply line La is PWM-controlled.
After step S5, the process returns to step S1.

Although not shown in the flowchart of FIG. 3, when any abnormality occurs as a control running on a control line different from the control shown in the flowchart of FIG. 3, the open / close valve Va of the compressed air supply line La, The first open / close valve (fuel cut-off valve) Vf1 and the second open / close valve (diesel dosing valve) Vf2 of the fuel supply line Lf are closed.
This is because when any abnormality occurs, the valves Va, Vf1, and Vf2 are closed to prevent the above situation from propagating to the fuel source or the compressed air source.

According to the illustrated embodiment, when the DPF 2 is not forcibly regenerated, the internal pressure Pa of the post-processing fuel injection mechanism 4 is controlled to be equal to or higher than the pressure Pe of the exhaust pipe 3. Therefore, the exhaust flowing through the exhaust pipe 3 is prevented from flowing into the line Lg in the aftertreatment fuel injection mechanism 4 having a pressure higher than that of the exhaust. And soot accumulation in the line Lg of the post-processing fuel injection mechanism 4 is reduced or prevented.
As a result, when the DPF 2 is forcibly regenerated, the target amount of fuel necessary for forced regeneration is reliably supplied from the post-processing fuel injection mechanism 4 to the exhaust pipe 3.

Here, the pressure Pa inside the aftertreatment fuel injection mechanism 4 only needs to be equal to or higher than the pressure Pe of the exhaust pipe 3, and does not need to be extremely high as compared with the pressure Pe of the exhaust pipe 3.
Therefore, the amount of compressed air discharged to the exhaust pipe 3 is saved, the compressed air is not wasted, and the operating rate of the air compressor that is the source of compressed air is reduced.
By reducing the operating rate of the air compressor, the fuel consumed for driving the auxiliary machinery is suppressed, and as a result, it contributes to fuel saving.

Further, the control device 10 maintains the open / close valve Va of the compressed air supply line La in an open state when the pressure Pe of the exhaust pipe 3 rises above a threshold value. The pressure Pa is also maintained at a high pressure.
Therefore, even when the pressure Pe of the exhaust pipe 3 increases, the state in which the amount of accumulated soot in the line Lg of the post-processing fuel injection mechanism 4 is reduced is maintained.

Further, according to the illustrated embodiment, when the DPF 2 is forcibly regenerated, the fuel is supplied to the exhaust pipe 3 by opening the first opening / closing valve Vf1 and the second opening / closing valve Vf2 of the fuel supply line Lf. .
As a result, the supplied fuel is oxidized, the temperature of the DPF 2 rises, and the soot accumulated in the DPF 2 is combusted. Then, the regeneration operation is performed satisfactorily.

Further, the first on-off valve Vf1 and the second on-off valve Vf2 of the fuel supply line Lf are closed and the on-off valve Va of the compressed air supply line La is opened for a predetermined period after the engine 1 is stopped. It is configured to perform driving.
In this case, since the engine 1 is stopped, the pressure Pe of the exhaust pipe 3 is reduced. And since the time has not passed so much after the engine 1 is stopped, the line Lg of the post-processing fuel injection mechanism 4 is also heated, soot is also heated and easily peeled off. By opening the opening / closing valve Va of the compressed air supply line La in such a state, the soot accumulated in the line Lg is easily removed (discharged to the exhaust pipe 3 side).

FIG. 4 shows a modification of the embodiment of FIGS.
In the embodiment of FIG. 1, the exhaust pipe pressure sensor (differential pressure sensor) 6 detects the pressure from the exhaust pipe 3 before and after the DPF 2 via the lines 7 and 8.
On the other hand, in the modification of FIG. 4, the differential pressure sensor 60 of the DPF detects the exhaust pressure on the inlet side of the DPF 2 via the line 7 and detects the atmospheric pressure via the line 9 to obtain the differential pressure. It is configured.
In FIG. 1, the exhaust resistance in the exhaust pipe behind the DPF 2 is approximately equal to atmospheric pressure. Therefore, even if the atmospheric pressure is detected via the line 9 in FIG. 4, the pressure Pe in the exhaust pipe 3 can be obtained as in the case of FIG.
Configurations and operational effects other than those described above in the modification of FIG. 4 are the same as those of the embodiment of FIGS.

The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, in the illustrated embodiment, the internal pressure Pa of the post-processing fuel injection mechanism 4 of the post-processing fuel addition device 100 is set to be equal to or higher than the pressure Pe of the exhaust pipe 3 of the engine 1. Valve) Va is PWM-controlled, but the internal pressure Pa of the post-processing fuel injection mechanism 4 is set to the pressure Pe of the exhaust pipe 3 of the engine 1 using a solenoid valve or a butterfly valve. It is also possible to perform the control described above.

1 ... Internal combustion engine / diesel engine 2 ... Filter / DPF
3 ... Exhaust pipe 4 ... Post-processing fuel injection mechanism 5 ... Nozzle 6 ... Exhaust pressure sensor / differential pressure sensor 10 ... Control device 41 ... Reverse of compressed air supply line Stop valve 42 ... Check valve 43 in the fuel supply line ... Pressure sensor La in the air / fuel supply mechanism ... Compressed air supply line Lf ... Fuel supply line Va ... On-off valve Vf1 ...・ First on-off valve Vf2 ... second on-off valve

Claims (6)

Post-processing fuel injection mechanism for supplying high-pressure air from the air supply system and fuel from the fuel supply system to the exhaust system between the internal combustion engine and a filter that collects harmful particulate components in the exhaust gas from the nozzle In the aftertreatment fuel addition apparatus having the above, the fuel supply system is connected from the fuel supply source to the junction of the air supply system via the first on-off valve and the second on-off valve, and the air supply system The fuel supply source is connected to the junction through a third on-off valve, and the junction is connected to the nozzle through a line between the first on-off valve and the second on-off valve. A first measuring device that measures the pressure inside the fuel supply system, a second measuring device that measures the differential pressure between the upstream side of the filter and the downstream side of the filter or the atmospheric pressure, and the first measuring device. And the second measuring device And a control device that opens and closes the first, second, and third on-off valves based on the measurement result, and the control device measures the measurement result from the second measurement device that measures the pressure of the exhaust system of the internal combustion engine. When the filter for collecting harmful particulate components in the exhaust gas flowing through the exhaust system of the internal combustion engine is not forcibly regenerated based on the measurement result of the first measurement device, the internal pressure of the fuel supply system An aftertreatment fuel addition device having a function of controlling the pressure to be equal to or higher than an engine exhaust system pressure. When the control device does not forcibly regenerate the filter that collects harmful particulate components in the exhaust gas flowing through the internal combustion engine exhaust system, the internal pressure of the fuel supply system becomes equal to or higher than the pressure of the internal combustion engine exhaust system. The post-processing fuel addition device according to claim 1, having a function of appropriately setting a time for turning on and off a third on-off valve. When the control device does not forcibly regenerate the filter that collects harmful particulate components in the exhaust gas flowing through the internal combustion engine exhaust system, and the pressure of the internal combustion engine exhaust system is greater than the threshold value, closes the second on-off valve of the fuel supply system, post-treatment fuel addition according to claim 1, 2 or Re without noise having the function of maintaining the third opening and closing valve of the air supply system in an open state apparatus. The control device opens the first on-off valve and the second on-off valve of the fuel supply system when forcibly regenerating the filter that collects harmful particulate components in the exhaust gas flowing through the exhaust system of the internal combustion engine. The post-processing fuel addition device according to claim 3, which has a function of supplying fuel to an exhaust system of an internal combustion engine. The control device closes the first on-off valve and the second on-off valve of the fuel supply system and opens the third on-off valve of the air supply system for a predetermined period after the internal combustion engine stops. post-treatment fuel addition device according to any Re without gall claim 3, 4 having the function of. 6. The control device according to claim 3, wherein the controller has a function of closing the third on- off valve of the air supply system, the first on-off valve of the fuel supply system, and the second on-off valve when an abnormality occurs. post-treatment fuel addition device according to any Re not have.

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