JP2001073743A - Exhaust purifying device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut off fuel consumed by burner for filter regeneration treatment. SOLUTION: In case filter regeneration is carried out, fuel consumed by burner equipment 20 is cut off by making use of exhaust heat by opening exhaust passage 10 a little, controlling opening angle controlling valve 18 with by-pass 14 almost open all the way, thus guiding part of exhaust gas in operation to filter 12. Also, mixing of fuel spray, catalyst air and exhaust gas is promoted, and fuel consumed by burner equipment 20 is further cut off by providing air supply passage 34 protruding into exhaust passage 10 for supplying catalyst air, by forming its tip as ejector shape making cross section area of passage smaller, and by fitting fuel injecting nozzle 25 so that fuel spray from burner equipment 20 is injected along flow of catalyst air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for a diesel engine, and more particularly to a technique for reducing fuel consumed by a burner as filter regeneration means.

[0002]

2. Description of the Related Art Conventionally, a diesel particulate filter (hereinafter referred to as "DP") has been used to collect particulate matter contained in exhaust gas of a diesel engine by a filter and improve the exhaust property.
F ") system is known. In the DPF system, since the filter is clogged with the collection of the particulate matter, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 5-64412 and Japanese Patent Application Laid-Open No. 8-170520, the filter regeneration means is used. It is necessary to perform a filter regeneration process for incinerating the particulate matter collected by the filter by the electric heater, the burner or the like.

[0003]

However, in the case where the filter regeneration process is performed by a burner, the mixing of the fuel spray from the fuel injection nozzle and the air as the auxiliary combustion air is not good (while the engine is stopped). Alternatively, there is a problem that mixing of fuel spray, air and exhaust is not good (during operation of the engine). In addition, since the conditions are different between when the engine is operating and when the engine is stopped, there is also a problem that it is difficult to supply the necessary and appropriate air amount for the combustion of the burner in addition to the combustion of the particulate matter collected by the filter. there were. For this reason, the particulate matter collected by the filter cannot be incinerated efficiently, and the burner consumes a lot of fuel, which is not economical.

In view of the above problems, the present invention promotes fuel spray, mixing of air and exhaust gas, and controls the amount of particulate matter and air supplied to a burner, thereby regenerating a filter. The present invention relates to a technique for reducing fuel consumed by a burner as a means.

[0005]

According to a first aspect of the present invention, there is provided a filter which is interposed in an exhaust passage of a diesel engine and collects particulate matter in exhaust gas. A burner for regenerating the filter by incineration of the particulate matter; a bypass passage connected to the exhaust passage so as to bypass the filter; and an open passage provided at a branch of the exhaust passage and the bypass passage. Opening control means for controlling the degree of opening of the exhaust passage and the bypass passage through a degree control valve, and auxiliary combustion air supply for supplying auxiliary combustion air for burning particulate matter collected by the burner and the filter. Means for exhaust gas purification of a diesel engine, wherein the opening degree control means substantially fully opens the bypass passage when performing a filter regeneration process. While the opening control valve is controlled to be slightly opened, when the filter regeneration process is not performed, the exhaust passage is fully opened and the opening control valve is controlled so as to fully close the bypass passage. The auxiliary air supply means has an air supply passage protruding into the exhaust passage, and the tip of the air supply passage is formed in an ejector shape having a small passage cross-sectional area. The burner is disposed so as to inject fuel spray in a direction along the flow of the auxiliary combustion air in the air supply passage, and an ignition electrode for igniting the fuel spray near the fuel injection hole is provided. It is characterized in that it is a configuration integrally provided.

With this configuration, when the filter regeneration process is not performed, the exhaust passage is controlled to be fully open and the bypass passage is controlled to be fully closed. Therefore, the entire amount of exhaust gas from the diesel engine is introduced into the filter, and the exhaust properties are improved.
On the other hand, when performing the filter regeneration processing, control is performed so that the bypass passage is substantially fully opened and the exhaust passage is slightly opened. For this reason, when the engine is operating, a part of the exhaust gas is introduced into the filter, so that the temperature of the filter rises due to the exhaust heat and the fuel consumed by the burner decreases. In addition, when the engine is stopped, heat for filter regeneration is suppressed from being released into the atmosphere via the bypass passage, so that fuel consumed by the burner is reduced as in the case of operating the engine. .

Further, since the tip of the air supply passage is formed in an ejector shape, the velocity of the auxiliary combustion air is increased at the tip of the air supply passage. Then, the fuel spray injected from the burner and the auxiliary combustion air whose flow velocity has increased are mixed, and the air-fuel mixture is ignited by the ignition electrode. At this time, the flow rate of the air-fuel mixture of the fuel spray and the auxiliary air is still high, and when the filter regeneration is performed during operation of the engine, the mixing of the air-fuel mixture and the exhaust gas is promoted. That is, the mixture of fuel spray, combustion air and exhaust gas is promoted, and the fuel consumed by the burner is further reduced.

According to a second aspect of the present invention, there is provided an engine stop judging means for judging whether or not the diesel engine is stopped, and when the engine stop judging means judges that the diesel engine is stopped. And a first control means for controlling a burner so as to increase the fuel injection amount and controlling a combustion assisting air supply means so as to increase the combustion assisting air.

With this configuration, when the diesel engine is stopped, the fuel injection amount and the auxiliary air are increased, so that the time required for the filter regeneration can be reduced even when the exhaust heat cannot be used. .

According to a third aspect of the present invention, the filter has a surface coated with an oxidation catalyst, a filter temperature detecting means for detecting the filter temperature, and a filter temperature detected by the filter temperature detecting means. And control means for controlling the fuel injection amount from the burner and the auxiliary air supply amount by the auxiliary air supply unit so that the temperature is equal to or higher than the activation temperature of the oxidation catalyst. I do.

According to this configuration, the fuel injection amount and the auxiliary combustion air are controlled so that the filter temperature becomes equal to or higher than the activation temperature of the oxidation catalyst, so that the time required for filter regeneration is reduced.

According to a fourth aspect of the present invention, there is provided a combustion judging means for judging whether or not the particulate matter trapped in the filter is burning, and the particulate matter being burned by the burning judging means. And a third control means for controlling the auxiliary air supply means so as to increase the auxiliary air when the determination is made and controlling the burner so as to reduce the fuel injection amount. It is characterized by.

According to this configuration, when the particulate matter trapped in the filter is burning, the amount of fuel-assisted air is increased and the fuel injection amount is reduced, so that the self-sustaining combustion of the particulate matter is promoted. Is done.

According to a fifth aspect of the present invention, a baffle for diffusing a flame from the burner to a peripheral portion of the filter is disposed at a substantially central portion immediately upstream of the filter. .

According to this configuration, when the flame from the burner hits the baffle, the flame is diffused to the periphery of the filter, so that the temperature of the filter rises substantially uniformly in the cross section.

According to a sixth aspect of the present invention, a windshield is provided near the fuel injection hole of the burner so as to prevent the exhaust flowing through the exhaust passage from directly hitting the ignition electrode and the fuel injection hole. It is characterized by having a configuration.

According to this structure, the windshield is provided so that the exhaust flowing through the exhaust passage does not directly hit the ignition electrode and the fuel injection hole, so that the exhaust heat is transmitted to the burner via the exhaust. Is prevented, and the temperature rise of the burner is suppressed.

The invention according to claim 7 is characterized in that a heat shielding means is provided around the burner to prevent the burner from being overheated by exhaust heat. According to this configuration, overheating of the burner is prevented by the heat shielding means, so that the heat resistance and reliability of the burner are improved.

[0019] In a preferred embodiment of the present invention, the heat shielding means comprises:
It is a cooling water passage formed in a peripheral wall of the exhaust passage so as to cool the periphery of the burner. According to such a configuration, the cooling water flows through the cooling water passage formed on the peripheral wall of the exhaust passage, so that the cooling water takes heat from around the burner, thereby preventing the burner from overheating.

According to a ninth aspect of the present invention, the heat shielding means comprises:
It is a heat shielding member interposed between the burner and the exhaust passage. According to such a configuration, even if the exhaust passage becomes hot by receiving heat from the exhaust heat, the heat shielding member prevents the heat from being transmitted to the burner, and prevents the burner from overheating.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 1 shows a first embodiment of an exhaust gas purification device for a diesel engine (hereinafter, referred to as “exhaust gas purification device”) according to the present invention.

In the exhaust passage 10 of the diesel engine, a substantially cylindrical diesel particulate filter (hereinafter, referred to as a "filter") made of a porous material such as ceramic is provided.
12 are interposed. In the filter 12, a large number of cells substantially parallel to the exhaust gas flow are formed by honeycomb-shaped partitions, and the inlet and outlet of each cell are alternately plugged with a sealing material. When the exhaust gas flows into the adjacent cell through the partition, the particulate matter contained in the exhaust is collected by the partition. It is preferable that the surface of the filter 12 be coated with an oxidation catalyst in order to promote the combustion (oxidation) of the particulate matter collected by the filter 12.

A bypass passage 14 is connected to the exhaust passage 10 so as to bypass the filter 12. An opening control valve 18 driven by an actuator 16 is interposed at the inlet of the bypass passage 14 so as to control the opening area (opening) of the exhaust passage 10 and the bypass passage 14 from fully open to fully closed. .

Exhaust passage 10 upstream of filter 12
Is provided with a burner device 20 using light oil, kerosene or the like as a fuel, and an air supply device 30 (combustion air supply means) for supplying combustion burn air (air) necessary for burning the burner and particulate matter. You.

The air supply device 30 includes an air filter 31 for removing dust and the like from the atmosphere, a blower 32 for supplying air from which the dust and the like have been removed by the air filter 31, and an electric motor 33 for driving the blower 32. , And an air supply passage 34 protruding into the exhaust passage 10. Here, the air supply passage 34 is formed in a so-called ejector shape so that the cross-sectional area of the passage is gradually reduced at a portion protruding into the exhaust passage 10. Therefore, the flow rate of the auxiliary combustion air supplied into the exhaust passage 10 via the air supply passage 34 becomes higher toward the outlet.

The burner device 20 includes a fuel tank 21 for storing fuel, a strainer 22 for filtering impurities contained in the fuel, a fuel pump 23 for supplying fuel under pressure, and an electric motor 24 for driving the fuel pump 23. , A fuel injection nozzle 25, and an ignition device 26 for generating a high voltage for ignition. The fuel injection nozzle 25 is
The fuel spray is provided near the outlet of the air supply passage 34 so as to spray the fuel spray along the flow of the auxiliary combustion air flowing through the air supply passage 34. Note that, in order to prevent the fuel injection nozzle 25 from being directly exposed to the high-temperature exhaust gas, it is desirable that the fuel injection nozzle 25 be disposed so as to be accommodated in the air supply passage 34. Also, the fuel injection hole 2 of the fuel injection nozzle 25
An ignition electrode 25b for igniting the fuel spray is attached near 5a, and a high voltage is applied to the ignition electrode 26 from the ignition electrode 25b.

On the peripheral walls of the exhaust passage 10 and the air supply passage 34, a water jacket 40 (cooling water passage) for cooling the periphery of the fuel injection nozzle 25 is formed, and cooling water is supplied from a radiator (not shown). Is done. Cooling water is controlled via a water pump 44 driven by an electric motor 42. Therefore, the water pump 4
4 prevents the fuel injection nozzle 25 from being heated to a high temperature even if exhaust heat is transmitted to the fuel injection nozzle 25 or the exhaust heat is transmitted to the fuel injection nozzle 25 via the peripheral wall of the exhaust passage 10. Can be prevented from decreasing.

Incidentally, instead of the water jacket 40,
As in the second embodiment shown in FIG. 2, between the exhaust passage 10 and the air supply passage 34 and the fuel injection nozzle 25, heat shielding members 46a and 46 made of ceramic or the like having a low thermal conductivity are used.
b may be provided. Also, the fuel injection nozzle 2
A shield (draft shield) 4 that covers the fuel injection holes 25a and the ignition electrodes 25b so as to prevent the fuel cell 5 from being directly exposed to high-temperature exhaust gas.
8 may be provided.

Here, the water jacket 40 and the heat shielding members 46a and 46b correspond to heat shielding means. further,
As the flame from the fuel injection nozzle 25 hits directly,
A baffle 50 as shown in FIG. 3 is disposed immediately upstream of the filter 12 and substantially at the center. That is, the baffle 50
It has a shape in which a part of a spherical surface is cut out, and a plurality of holes 50a and 50b are formed in a substantially central portion and a peripheral portion. Therefore, the flame from the fuel injection nozzle 25 reaches the filter 12 through the holes 50a and 50b of the baffle 50, and is diffused to the periphery by the baffle 50, and the filter 1
2 It also reaches the outer periphery. The baffle 50 is not limited to the shape shown in the drawing, and may have, for example, a shape obtained by cutting off a part of a cone.

On the other hand, the control system of the exhaust gas purification device includes a temperature sensor 60 (filter temperature detecting means) for detecting an exhaust gas temperature t ₁ on the upstream side of the filter 12 corresponding to the filter temperature, and an exhaust gas temperature t ₂ on the downstream side of the filter 12. Temperature sensor 62 for detecting
And a pressure sensor 64 that detects an exhaust pressure (hereinafter, referred to as “exhaust pressure”) p on the upstream side of the filter 12 and a control unit 66 including a microcomputer. The control unit 66 also receives the engine speed Ne or the engine “ON / OFF” signal. The control unit 66 controls the actuator 16 of the opening control valve 18, the electric motor 24 driving the fuel pump 23, the electric motor 33 driving the blower 32, and the ignition device 26 in accordance with various input signals.

Here, the control unit 66 includes an opening control means, an engine stop determination means, a first control means, and a second control means.
The control means, the combustion determination means and the third determination means are realized by software.

Next, the operation of the exhaust gas purifying apparatus having the above configuration will be described with reference to the flowcharts of FIGS. FIG. 4 is a flowchart of a main routine showing control contents of the exhaust gas purification device. Note that the main routine is repeatedly executed at predetermined time intervals.

Step 1 (abbreviated as "S1" in the figure)
In the following), it is determined whether it is necessary to perform the filter regeneration process. That is, it is determined whether or not the exhaust pressure p detected by the pressure sensor 64 is larger than a predetermined value by utilizing the property that the exhaust pressure increases when the filter 12 is clogged by the collected particulate matter. If the exhaust pressure p is larger than the predetermined value, the process proceeds to step 2 (Yes), and if the exhaust pressure p is equal to or less than the predetermined value, the process proceeds to step 4 (N
o).

In step 2, since the exhaust pressure p has become larger than the predetermined value, a subroutine (see FIG. 5) for performing the filter regeneration process is called to perform the filter regeneration process.

In step 3, taking into account that a certain amount of time is required to incinerate the collected particulate matter,
It is determined whether a predetermined time has elapsed since the start of the filter regeneration process. If the predetermined time has elapsed, the process proceeds to step 4 (Yes). If the predetermined time has not elapsed, the process returns to step 2 (No), and the filter regeneration process is continued.

In step 4, since the filter regeneration process is completed or the filter regeneration process is unnecessary, a subroutine for performing normal operation (see FIG. 6) is called.
According to the main routine, it is determined whether or not the filter regeneration process needs to be performed based on the exhaust pressure p, and the filter regeneration process or the normal operation is performed according to the determination result. The determination as to whether or not it is necessary to perform the filter regeneration process is not limited to the determination method according to the present embodiment. For example, when the difference between the exhaust pressure on the upstream side and the exhaust pressure on the downstream side of the filter 12 becomes a predetermined value or more. Then, it may be determined that it is necessary.

FIG. 5 shows a flowchart of a subroutine for performing a filter regeneration process. In step 11, the opening control valve 18 is controlled via the actuator 16 so that the bypass passage 14 is substantially fully opened and the exhaust passage 10 is slightly opened. The control of the opening control valve 18 in step 11 corresponds to a part of the opening control means.

In steps 12 to 16, a series of processes for igniting the burner device 20 are performed. That is, when the burner device 20 is ignited, in view of the fact that the exhaust gas temperature t ₁ on the upstream side of the filter 12 increases, it is determined in step 12 whether the exhaust gas temperature t ₁ detected by the temperature sensor 60 is equal to or higher than a predetermined value. Is determined. If the exhaust temperature t ₁ is equal to or higher than the predetermined value (Yes), the ignition electrode 25
b, the ignition device 26 is operated to apply a high voltage (step 13), and the fuel pump 23 is operated to inject fuel spray from the fuel injection nozzle 25 (step 1).
4) The blower 32 is operated to supply the fuel spray and the particulate combustion material with the auxiliary air (step 15). On the other hand, if the exhaust gas temperature t ₁ is less than the predetermined value, the process proceeds to step 16 (N
o), the operation of the ignition device 16 is stopped.

In steps 17 to 21, a series of processes are performed to quickly raise the filter temperature to the minimum temperature required for filter regeneration (the temperature at which the oxidation catalyst is activated). That is, in step 17, the exhaust gas temperature t ₁ detected by the temperature sensor 60 is equal to or a predetermined catalyst activation temperature (hereinafter referred to as "activation temperature") is determined. If the exhaust temperature t ₁ is equal to or higher than the activation temperature (Yes), the amount of the auxiliary air is reduced by controlling the blower 32 (step 18), and the amount of fuel injection is reduced by controlling the fuel pump 23 (step 19). . On the other hand, exhaust temperature
If t ₁ is less than the predetermined temperature (No), in a similar manner, the amount of fuel injection is increased (step 20), combustion support air is increased (step 21).

The processing in steps 17 to 21 corresponds to the second control means. In Steps 22 to 24, if the particulate matter trapped in the filter 12 is burning, the fuel is promoted to thereby burn the particulate matter.
A series of processes for reducing the fuel consumed at 0 is performed. That is, when the particulate matter is burned, in view of the fact that the exhaust temperature of the filter 12 downstream is higher than the upstream side, in step 22, detected by the temperature sensor 60 from the exhaust temperature t ₂ detected by the temperature sensor 62 It is determined whether a value (t ₂ −t ₁ ) obtained by subtracting the exhaust gas temperature t ₁ is equal to or more than a predetermined value. If the subtraction value (t ₂ −t ₁ ) is equal to or greater than the predetermined value (Yes), the auxiliary combustion air is increased (step 23), and the fuel injection amount is increased (step 2).
4). On the other hand, if the subtraction value (t ₂ −t ₁ ) is less than the predetermined value (No), it can be determined that the particulate matter is not burning, and the process proceeds to step 25.

The determination in step 22 corresponds to combustion determination means, and the processing in steps 23 and 24 corresponds to third control means. In steps 25 to 27, when the engine is stopped, a series of processes for increasing the fuel injection amount and the auxiliary combustion air are performed in view of the fact that the exhaust gas cannot be used as the auxiliary combustion air and the exhaust heat cannot be used. That is, in step 25, it is determined whether or not the engine is stopped based on the engine speed Ne or the engine ON / OFF signal. If it is determined that the engine is stopped (Yes), the fuel injection amount is increased (step 2).
6), the amount of auxiliary combustion air is increased (step 27). on the other hand,
If it is determined that the engine is not stopped (No), the processing of this subroutine ends, and the process returns to the main routine.

Note that the determination in step 25 corresponds to the engine stop determination means, and steps 26 and 27
Corresponds to the first control means. According to this subroutine for performing the filter regeneration processing, first, the opening control valve 18 is controlled so that the bypass passage 14 is substantially fully opened and the exhaust passage 10 is slightly opened. For this reason, when the engine is operating, a part of the exhaust gas passes through the gap between the opening control valve 18 and the exhaust passage 1.
0 is introduced into the filter 12. Therefore, compared to the case where the entire amount of exhaust gas is introduced, the filter temperature rises due to the exhaust heat of the exhaust gas introduced into the filter 12 and the fuel consumed by the burner device 20 is reduced while preventing excessive cooling due to excessive air amount. Can be reduced.

Then, the exhaust gas temperature t ₁ on the upstream side of the filter 12 is set.
However, the fuel injection amount and the auxiliary air are controlled to increase or decrease so that the temperature is at least the minimum temperature required for filter regeneration, that is, the temperature at which the oxidation catalyst is activated. For this reason, the time required for the filter regeneration processing is reduced, and from this viewpoint, it is possible to promote the reduction of the fuel consumed by the burner device 20.

Further, it is detected that the particulate matter trapped in the filter 12 has started to be burned, and the self-sustaining combustion of the particulate matter is promoted by increasing the auxiliary combustion air and decreasing the fuel injection amount. Thus, the fuel consumed by the burner device 20 can be further reduced.

Further, when the engine is stopped, the exhaust heat cannot be used, and it takes some time to regenerate the filter. However, by increasing the fuel injection amount and the auxiliary combustion air, the filter regeneration process can be completed in a short time. become able to.

FIG. 6 shows a flowchart of a subroutine for performing a normal operation. In step 31, the ignition device 2
6 is stopped. In step 32, the fuel injection is stopped.

In step 33, the auxiliary combustion air blowing is stopped. In step 34, the opening control valve 18 is controlled via the actuator 16 so that the exhaust passage 10 is fully opened and the bypass passage 14 is fully closed. Step 34
The control of the opening control valve 18 in the above corresponds to a part of the opening control means.

According to this subroutine for performing the normal operation, the opening control valve 1 is controlled so that the entire amount of exhaust gas passes through the filter 12 after the end of the filter regeneration process.
8 is controlled. For this reason, when the filter regeneration processing is not performed, the particulate matter is collected by the filter 12, and the exhaust property can be improved.

According to the processing of FIGS. 4 to 6 described above,
When the filter regeneration is performed while the engine is operating, a part of the exhaust gas is introduced into the filter 12 and the exhaust heat is used so that
The fuel consumed by the burner device 20 can be reduced. Also, quickly raise the filter temperature to the regeneration temperature,
Alternatively, the self-sustaining combustion is promoted when the captured particulate matter starts burning, so that the fuel consumed by the burner device 20 can be further reduced. Further, when performing the filter regeneration while the engine is stopped, the time required for the filter regeneration is reduced by increasing the fuel injection amount and the auxiliary combustion air, and as a result, the fuel consumed by the burner device 20 can be reduced. .

FIG. 7 shows a third embodiment of the exhaust gas purifying apparatus according to the present invention.
1 shows an embodiment. Note that the configuration of this embodiment is the same as that of the second embodiment, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

This embodiment is characterized in that a first opening control valve 72 driven by an actuator 70 is provided in the exhaust passage 10 and an actuator 7 is provided in the bypass passage 14.
4 in that a second opening control valve 76 driven by the control valve 4 is interposed. Thereby, the exhaust passage 10 and the bypass passage 14
Can be controlled independently of each other. Therefore, for example, the filter regeneration efficiency can be improved by controlling the opening of the exhaust passage 10 in detail according to the combustion state of the particulate matter.

A temperature sensor 78 for detecting the temperature t _{3 of the} shield 48 is provided to reliably determine whether or not the ignition of the burner device 20 has been completed. In this case, in step 17 of the subroutine (see FIG. 5) showing a filter regeneration process, in place of the subtraction value (t ₂ -t _1), may be used the temperature t _3.

The other control contents, functions and effects in the third embodiment are the same as those in the first and second embodiments, so that the description thereof will be omitted.

[0054]

As described above, according to the first aspect of the present invention, when the filter regeneration processing is not performed,
The entire amount of exhaust gas is introduced into the filter, and the exhaust properties can be improved. On the other hand, when performing the filter regeneration process, if the engine is operating, part of the exhaust gas is introduced into the filter and the exhaust heat is used, so that the fuel consumed by the burner can be reduced. In addition, when the engine is stopped, the heat for filter regeneration is suppressed from being released into the atmosphere, and the fuel consumed by the burner can be reduced. Further, since the tip of the air supply passage is formed in the shape of an ejector, mixing of fuel spray, auxiliary air and exhaust gas is promoted, and fuel consumed by the burner can be further reduced.

According to the second or third aspect of the present invention, since the time required for filter regeneration is reduced, the total fuel required for filter regeneration is reduced, and the fuel consumed by the burner is further reduced. be able to.

According to the fourth aspect of the present invention, since the self-sustaining combustion of the particulate matter collected by the filter is promoted, the fuel consumed by the burner can be further reduced. According to the fifth aspect of the present invention, since the temperature of the filter rises substantially uniformly with respect to its cross-sectional area, the particulate matter is incinerated in a short time, and the fuel consumed by the burner can be further reduced.

According to the sixth aspect of the invention, the burner is prevented from being directly exposed to the exhaust gas, and the temperature rise of the burner is suppressed, so that the heat resistance and reliability of the burner can be improved.

According to the seventh aspect of the present invention, overheating of the burner is prevented, so that the heat resistance and reliability of the burner can be improved. According to the eighth aspect of the present invention, the cooling water can take heat from around the burner and prevent the burner from overheating.

According to the ninth aspect of the present invention, heat is prevented from being transmitted from the exhaust passage to the burner by the heat shielding member, and overheating of the burner can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a partial configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a perspective view of a baffle.

FIG. 4 is a flowchart of a main routine showing control contents.

FIG. 5 is a flowchart of a subroutine showing a filter regeneration process.

FIG. 6 is a flowchart of a subroutine showing a normal operation process.

FIG. 7 is an overall configuration diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 exhaust passage 12 filter 14 bypass passage 18 opening control valve 20 burner device 25 fuel injection nozzle 25a fuel injection hole 25b ignition electrode 30 air supply device 34 air supply passage 40 water jacket 46a, 46b heat shielding member 48 shield 50 baffle 60 Temperature sensor 66 Control unit 72 First opening control valve 76 Second opening control valve

Claims (9)

[Claims] 1. A filter which is interposed in an exhaust passage of a diesel engine and collects particulate matter in exhaust gas, and a burner which regenerates the filter by burning the particulate matter collected by the filter. Opening of the exhaust passage and the bypass passage through a bypass passage connected to the exhaust passage so as to bypass the filter, and an opening control valve provided at a branch portion of the exhaust passage and the bypass passage. Exhaust gas purification device for a diesel engine, comprising: an opening control means for controlling the degree of combustion; and an auxiliary air supply means for supplying auxiliary air for burning the particulate matter trapped in the burner and the filter. Wherein the opening control means controls the opening control valve so that the bypass passage is substantially fully opened and the exhaust passage is slightly opened when performing the filter regeneration process. When the filter regeneration process is not performed, the exhaust passage is fully opened, and the opening degree control valve is controlled so as to fully close the bypass passage. It has an air supply passage that protrudes, and a tip end of the air supply passage,
The passage cross-sectional area is configured to have a small ejector shape, the burner is disposed in the air supply passage so as to inject fuel spray in a direction along a flow of auxiliary combustion air, An exhaust purification device for a diesel engine, wherein an ignition electrode for igniting fuel spray is integrally provided near a fuel injection hole. An engine stop determining means for determining whether or not the diesel engine is stopped; and determining the fuel injection amount when the engine stop determining means determines that the diesel engine is stopped. 2. The exhaust gas purifying apparatus for a diesel engine according to claim 1, further comprising: a first control unit that controls the burner so as to increase the amount of the combustion assist air and controls a combustion assist air supply unit so as to increase the amount of the combustion assist air. 3. 3. The filter has a surface coated with an oxidation catalyst, a filter temperature detecting means for detecting the filter temperature, and a filter temperature detected by the filter temperature detecting means for activating the oxidation catalyst. The control device according to claim 1, further comprising: a second control unit configured to control a fuel injection amount from the burner and an auxiliary air supply amount by the auxiliary air supply unit so that the temperature becomes equal to or higher than the temperature. Exhaust purification device for diesel engine. 4. A combustion judging means for judging whether or not the particulate matter collected by the filter is burning, and when the combustion judging means judges that the particulate matter is burning, A third control unit that controls the auxiliary combustion air supply unit so as to increase the auxiliary combustion air, and controls a burner so as to decrease the fuel injection amount. The exhaust gas purifying apparatus for a diesel engine according to any one of the above. 5. The filter according to claim 1, wherein a baffle for diffusing a flame from the burner to a peripheral portion of the filter is provided at a substantially central portion immediately upstream of the filter. An exhaust purification device for a diesel engine according to any one of the above. 6. A structure in which a windshield is provided near the fuel injection hole of the burner to prevent exhaust gas flowing through an exhaust passage from directly hitting the ignition electrode and the fuel injection hole. The exhaust gas purification device for a diesel engine according to any one of claims 1 to 5. 7. The diesel engine according to claim 1, wherein a heat shielding means is provided around the burner to prevent the burner from being overheated by exhaust heat. Exhaust gas purification device. 8. The exhaust gas purifying apparatus for a diesel engine according to claim 7, wherein said heat shielding means is a cooling water passage formed in a peripheral wall of said exhaust passage so as to cool the periphery of said burner. 9. The exhaust gas purifying apparatus for a diesel engine according to claim 7, wherein said heat shielding means is a heat shielding member interposed between said burner and an exhaust passage.