JP5981212B2 - Exhaust purification device burner - Google Patents

Description

  The technology of the present disclosure is applied to an exhaust purification device that purifies exhaust from an engine, and relates to an exhaust purification device burner that raises the temperature of the exhaust.

  Conventionally, a diesel particulate filter (DPF: Diesel Particulate Filter) that captures particulates (PM) contained in exhaust gas is disposed in an exhaust passage of a diesel engine. In such a DPF, in order to maintain the fine particle capturing function, a regeneration process is performed in which the fine particles captured by the DPF are incinerated.

  For example, in the exhaust gas purification apparatus of Patent Document 1, a burner is disposed in front of the DPF, and the DPF regeneration process is performed by causing the exhaust gas heated by the burner to flow into the DPF. In the burner, engine fuel and combustion air are supplied to a combustion region that is an internal space of a flame holder having a bottomed cylindrical shape, and an air-fuel mixture is generated by the fuel and the combustion air. And the exhaust gas is heated by burning the mixture by ignition.

  Further, in the exhaust purification device described above, the flame holder has a double cylindrical shape, and a part of the intake air compressed by the turbocharger is used as combustion air in the gap between the inner cylinder and the outer cylinder. Have been supplied. This combustion air is supplied to the combustion region from a first supply port formed on the bottom side of the flame holder with respect to the ignition point and a second supply port formed on the tip side of the flame holder with respect to the ignition point. As a result, the combustion air from the first supply port improves the ignitability of the air-fuel mixture by suppressing oxygen shortage near the ignition point, and the combustion air is supplemented to the combustion region by the combustion air from the second supply port. As a result, the combustibility of the air-fuel mixture is improved.

JP 2011-185493 A

  By the way, in the exhaust purification apparatus described above, when the combustion air supplied to the gap between the inner cylinder and the outer cylinder decreases, the combustion air supplied from the first supply port to the combustion region also decreases, so that the vicinity of the ignition point. Oxygen shortage occurs and the air-fuel mixture becomes difficult to ignite. Therefore, in order to ignite the air-fuel mixture with a high probability even with a small amount of combustion air, more combustion air is supplied from the first supply port to the combustion region than the second supply port. It is necessary to change the shape and number of the first and second supply ports. However, such a configuration causes a new problem that when the supply amount of combustion air increases, the flow velocity of the combustion air near the ignition point increases and the air-fuel mixture becomes difficult to ignite. That is, in the above-described exhaust purification device, there is still room for improvement in terms of the ignitability of the air-fuel mixture.

  The technology of the present disclosure is an exhaust purification that can improve the ignitability of an air-fuel mixture in a burner for an exhaust gas purification device that raises the temperature of exhaust gas flowing into a filter by burning the air-fuel mixture of fuel and air by ignition. An object is to provide an apparatus burner.

One aspect of the burner for an exhaust gas purification apparatus according to the present disclosure includes a cylindrical flame holder having a discharge port from which a combustion gas obtained by burning a mixture of fuel and air is blown, and a combustion region in the flame holder An igniter that ignites the air-fuel mixture and a supply passage that opens to the combustion region and supplies air from the supply port to the combustion region, and the air that the engine takes in The supply passage that communicates with the flowing intake pipe, and a branch port that is connected in the middle of the supply passage and opens to the combustion region, and a part of the air in the supply passage is burned from the branch port A diversion passage for supplying to the region, wherein the diversion port is disposed at a position closer to the ejection port than the supply port and the ignition portion, and a part of the air in the supply passage is provided in the diversion passage Shut-off state not shunted and shunt flow shunted Further comprising switching unit for switching the on purpose, the switching unit, the intake air quantity sensor for detecting an intake air amount of the engine, said supply passage and said branch flow path and a non-communicated state or switching valve for switching the communicating state And a control unit that controls the opening degree of the switching valve, and the control unit controls the switching valve to be closed when the intake air amount detected by the intake air amount sensor is equal to or less than a threshold value. The shut-off state is selected, and when the intake air amount detected by the intake air amount sensor exceeds the threshold value, the diversion state is selected by controlling the switching valve to the open state .

According to one aspect of the exhaust gas purification apparatus burner of the present disclosure, when the amount of air supplied to the combustion region is equal to or less than the threshold value, a part of the air in the supply passage is blocked from being divided into the branch passage. That is, air is supplied to the combustion region only from the supply port of the supply passage. For this reason, more air is supplied to the vicinity of the ignition portion than when air is supplied to the combustion region from both the supply passage and the diversion passage. As a result, even when the supply amount of air is small, it is possible to prevent the air-fuel mixture from becoming difficult to ignite due to insufficient oxygen in the vicinity of the ignition part.
In addition, since the opening / closing of the switching valve is controlled by the control unit, compared with a case where the switching valve is a differential pressure valve that operates based on a pressure difference between the upstream side and the downstream side of the switching valve, for example, in the combustion region. The switching valve can be opened and closed according to the amount of air supplied with high reliability.

  On the other hand, when the amount of air supplied to the combustion region exceeds the threshold, a part of the air in the supply passage is diverted to the branch passage. That is, air is supplied to the combustion region from both the supply port and the diversion port. Therefore, compared with the case where air is supplied to the combustion region only from the supply port, the amount of air supplied to the vicinity of the ignition part is reduced, and the flow velocity of air near the ignition part is reduced. As a result, even when the amount of air supplied is large, the air-fuel mixture is less likely to be ignited by the air flowing in the vicinity of the ignition portion.

  For these reasons, according to the burner for an exhaust gas purification apparatus having the above-described configuration, the air supply path to the combustion region is changed in accordance with the air supply amount, so that the ignitability of the air-fuel mixture can be improved. it can.

  In another aspect of the exhaust gas purification apparatus burner according to the present disclosure, the ignition unit is disposed between a portion facing the supply port and a portion facing the diversion port in the combustion region.

  According to another aspect of the burner for an exhaust gas purification apparatus according to the present disclosure, the supply port is connected to the combustion region as compared with the case where the supply port communicates with the combustion region on the flame outlet side of the flame holder. The probability that the supplied air passes near the ignition part can be increased. As a result, oxygen shortage near the igniting portion can be suppressed when the amount of air supply is small, and the ignitability of the air-fuel mixture can be further enhanced.

  In another aspect of the burner for an exhaust gas purification apparatus according to the present disclosure, the flame holder includes a cylindrical portion surrounding the combustion region, the cylindrical portion is expanded toward the ejection port, and the ignition portion is The enclosure includes a small diameter portion in which the supply port is formed and a large diameter portion in which the diversion port is formed.

  According to the other aspect of the burner for exhaust gas purification apparatus in the present disclosure, the flame generated at the small diameter portion is expanded at the large diameter portion. When the air supply amount exceeds the threshold value, air is supplied to the expanded flame. As a result, the unburned fuel and air contained in the flame are easily mixed, so that the unburned fuel contained in the flame can be reduced.

  In another aspect of the burner for an exhaust gas purification apparatus according to the present disclosure, the flame holder is formed with a plurality of the supply ports and a plurality of the diversion ports, and a total opening area of the plurality of the diversion ports is a plurality of It is larger than the total opening area of the supply port.

  According to another aspect of the burner for an exhaust gas purification apparatus according to the present disclosure, when the switching unit is in the diverted state, the ignition unit as compared with the case where the total opening area of the diverting port is not larger than the total opening area of the supply port. Since the flow velocity of air in the vicinity is suppressed, it is possible to supply more air to the combustion region.

  In another aspect of the burner for an exhaust gas purification apparatus according to the present disclosure, the flame stabilizer surrounds the inner cylinder, which is a cylinder portion surrounding the combustion region, and the inner cylinder, and a gap between the inner cylinder and the inner cylinder is a gap of the inner cylinder. An outer cylinder closed at both ends, and a partition wall that partitions a gap between the inner cylinder and the outer cylinder into a first chamber and a second chamber, and constitutes the first chamber of the inner cylinder The supply port is formed in a portion, the flow dividing port is formed in a portion of the inner cylinder that constitutes the second chamber, the supply passage includes the first chamber, and the flow distribution passage includes the first flow passage. The diversion passage is disposed in the pipe that communicates the first chamber and the second chamber on the outer peripheral surface of the outer cylinder, and the first chamber and the second chamber. And a switching valve that switches between communication and non-communication with the chamber.

  According to another aspect of the burner for an exhaust gas purification apparatus in the present disclosure, in the supply passage, air that has flowed into the first chamber is supplied to the combustion region through the supply port. In the branch passage, part of the air flowing into the first chamber is supplied to the combustion region through the pipe, the second chamber, and the branch port.

The figure which shows schematic structure of the exhaust gas purification device by which one Embodiment of the burner for exhaust gas purification devices in this indication was mounted. The flowchart which shows the process sequence of the switching valve opening / closing process in this embodiment. The graph which shows the relationship between the amount of intake air in this embodiment, and the air supply amount from a supply port.

  Hereinafter, an embodiment that embodies the burner for an exhaust gas purification apparatus according to the present disclosure will be described with reference to FIGS. 1 to 3. First, the overall configuration of an exhaust emission control device on which an exhaust emission control burner is mounted will be described with reference to FIG.

  As shown in FIG. 1, the exhaust gas purification device 10 for a diesel engine is disposed on the downstream side of the exhaust pipe 11. The exhaust purification device 10 is equipped with a diesel particulate filter 12 (hereinafter referred to as DPF 12) that adsorbs particulates contained in the exhaust.

  The DPF 12 has a honeycomb structure formed of, for example, porous silicon carbide, and traps particulates in the exhaust gas on the inner wall surface of the pillar body constituting the honeycomb structure. Further, an exhaust purification device burner 15 (hereinafter simply referred to as a burner 15) that performs regeneration processing of the DPF 12 by raising the temperature of the exhaust gas flowing into the DPF 12 is mounted on the front stage of the DPF 12.

  The flame holder 16 of the burner 15 has a cylindrical shape with a bottom, a peripheral wall is fixed to the bottom wall 17 of the flame holder 16, a small diameter portion 18 having a smaller diameter than the bottom wall 17, and a small diameter portion 18. And a large-diameter portion 19 that is connected to the peripheral wall at the tip of the nozzle and expands the flame holder 16 over the ejection port 16A. The small diameter portion 18 and the large diameter portion 19 constitute a cylindrical portion of the flame holder 16. In the flame stabilizer 16, a combustion region 20 is formed by a space surrounded by the peripheral wall of the small diameter portion 18 and the peripheral wall of the large diameter portion 19.

  A fuel injection valve 21 that is a fuel supply portion and a pair of spark plugs 22 are fixed to the bottom wall 17 of the flame stabilizer 16 on the inner side of the connecting portion with the peripheral wall of the small diameter portion 18. The fuel injection valve 21 is provided with a tip portion where an injection port is formed in the combustion region 20, and injects fuel toward the combustion region 20 to supply mist-like fuel to the combustion region 20. A fuel pump for supplying fuel to an engine (not shown) is connected to the fuel injection valve 21. The spark plug 22 is disposed so that an ignition portion 22a, which is a tip portion thereof, surrounds the tip portion of the fuel injection valve 21. The spark plug 22 ignites the mixture of fuel and combustion air at an ignition point 23 by generating a spark in the combustion region 20. Thereby, a flame F is generated in the combustion region 20.

  In addition, a cylindrical outer cylinder 24 surrounding the peripheral walls of the small diameter portion 18 and the large diameter portion 19 is attached to the flame holder 16. The outer cylinder 24 has a peripheral wall at one end of the outer cylinder 24 fixed to the bottom wall 17 and a peripheral wall at the other end of the outer cylinder 24 fixed to the large-diameter portion 19. A gap between the small diameter portion 18 and the large diameter portion 19 and the outer cylinder 24 is a space on the bottom wall 17 side of the flame holder 16 by a partition wall 25 disposed on the tip side of the flame holder 16 with respect to the ignition point 23. Are divided into a first chamber 26 and a second chamber 27 which is a space on the ejection port 16A side of the flame holder 16.

  The first chamber 26 communicates with the combustion region 20 through a supply port 31 formed in the small diameter portion 18. The supply ports 31 are formed at predetermined intervals over the entire circumference of the small diameter portion 18, and are openings that face the combustion region 20 on the bottom wall 17 side of the flame holder 16 from the ignition point 23, that is, the ignition portion 22 a.

  On the other hand, the second chamber 27 communicates with the combustion region 20 through a diversion port 32 formed in the large diameter portion 19. The diversion ports 32 are formed at predetermined intervals over the entire circumference of the large-diameter portion 19 and are openings facing the combustion region 20 on the side of the ejection port 16 </ b> A of the flame holder 16 from the ignition point 23. Further, the total opening area of the diversion port 32 is formed larger than the total opening area of the supply port 31.

  An air supply pipe 36 is fixed to the bottom wall 17 of the flame holder 16 to guide a part of the intake air flowing through the intake pipe 35 to the first chamber 26 as combustion air in a state compressed by the compressor of the turbocharger. Yes. An air valve 37 is attached in the middle of the air supply pipe 36. That is, part of the intake air flowing through the intake pipe 35 flows into the first chamber 26 through the air supply pipe 36 when the air valve 37 is open.

  In addition, a shunt pipe 38 that guides a part of the combustion air flowing into the first chamber 26 to the second chamber 27 is fixed to the outer cylinder 24. The flow dividing pipe 38 is a pipe that extends from the outer peripheral surface of the outer cylinder 24 and is routed outside the outer cylinder 24, and a switching valve 39 is disposed in the middle of the flow dividing pipe 38. The switching valve 39 maintains the first chamber 26 and the second chamber 27 in a non-communication state when closed, and maintains the first chamber 26 and the second chamber 27 in a communication state when opened.

  That is, in the burner 15, when the air valve 37 is open and the switching valve 39 is closed, the combustion air that has flowed into the first chamber 26 from the air supply pipe 36 is supplied to the combustion region 20 through the supply port 31. The combustion air in the first chamber 26 is cut off from being divided into the flow dividing pipe 38. On the other hand, when both the air valve 37 and the switching valve 39 are in the open state, a part of the combustion air flowing into the first chamber 26 from the air supply pipe 36 is diverted to the diversion pipe 38, and the supply port 31 and the diversion port 32. It becomes a diversion state supplied to the combustion region 20 through both.

Next, the electrical configuration of the burner 15 having the above-described configuration will be described with reference to FIG.
The fuel injection valve 21, the spark plug 22, the air valve 37, and the switching valve 39 constituting the burner 15 are driven by an ECU (Electronic Control Unit) 40 that is a control unit. The ECU 40 includes a CPU, a ROM that stores various control programs and various data, a RAM that temporarily stores calculation results and various data in various calculations, and the like, and various types based on the control programs stored in the ROM. Execute the process.

  A detection signal indicating an exhaust flow rate upstream of the DPF 12 is input to the ECU 40 at a predetermined control cycle from an upstream exhaust flow rate sensor 41 disposed on the upstream side of the DPF 12 in the exhaust pipe 11. A detection signal indicating an exhaust flow rate downstream of the DPF 12 is input to the ECU 40 at a predetermined control cycle from a downstream exhaust flow rate sensor 42 disposed on the downstream side of the DPF 12 in the exhaust pipe 11. A detection signal indicating the temperature of the DPF 12 is input to the ECU 40 at a predetermined control cycle from a temperature sensor 43 that detects the temperature of the DPF 12. A detection signal indicating the intake air amount Q is input to the ECU 40 at a predetermined control cycle from an intake air amount sensor 44 that detects the flow rate of the intake air flowing through the intake pipe 35.

  The ECU 40 calculates the amount of particulates accumulated in the DPF 12 based on the exhaust flow rate detected by the upstream exhaust flow rate sensor 41 and the exhaust flow rate detected by the downstream exhaust flow rate sensor 42. The ECU 40 executes the regeneration process of the DPF 12 when the calculated accumulation amount becomes higher than a preset threshold value α. Further, the ECU 40 ends the regeneration process when the accumulation amount of the particulates calculated during the regeneration process is lower than a preset threshold value β (<α).

  When the regeneration process is started, the ECU 40 outputs a control signal for keeping the air valve 37 open to the air valve 37. The air valve 37 to which the control signal is input is maintained in an open state in which a part of the intake air flowing through the intake pipe 35 flows into the first chamber 26 through the air supply pipe 36. When the regeneration process ends, the ECU 40 outputs a control signal indicating that the air valve 37 is kept closed to the air valve 37. The air valve 37 to which the control signal is input is maintained in a closed state in which intake air is prohibited from flowing into the first chamber 26 through the air supply pipe 36.

  In addition, when the regeneration process is started, the ECU 40 outputs a control signal for driving the spark plug 22 in a stopped state to the spark plug 22. The spark plug 22 to which the control signal is input is maintained in a driving state in which a spark is generated near the ignition point 23. When the regeneration process ends, the ECU 40 outputs a control signal for stopping the driving of the spark plug 22 in the drive state to the spark plug 22. When the control signal is input, the spark plug 22 is maintained in a stopped state in which no spark is generated in the vicinity of the ignition point 23.

  When the regeneration process is started, the ECU 40 detects the exhaust flow rate detected by the upstream exhaust flow rate sensor 41, the temperature of the DPF 12 detected by the temperature sensor 43, the intake air amount Q detected by the intake air amount sensor 44, and the like. Based on this, the fuel injection amount injected from the fuel injection valve 21 into the combustion region is calculated at a predetermined control cycle. The ECU 40 outputs a control signal to the fuel injection valve 21 so that the calculated fuel injection amount is injected into the combustion region 20. The fuel injection valve 21 injects fuel according to the control signal input to the fuel injection valve 21.

  Further, when the regeneration process is started, the ECU 40 performs a switching valve opening / closing process for switching the switching valve 39 to a closed state or an open state based on the intake air amount Q detected by the intake air amount sensor 44 at a predetermined control cycle. Run. In the switching valve opening / closing process, the ECU 40 controls the switching valve 39 to be closed when the intake air amount Q is equal to or less than a predetermined threshold value Qt, and when the intake air amount Q exceeds the threshold value Qt. The switching valve 39 is controlled to open. This threshold value Qt is a value that is set based on the results of experiments performed in advance, the results of simulations, and the like. When the combustion air is supplied from only the supply port 31 to the combustion region 20, the threshold value Qt is near the ignition point 23. It is a value at which the flow rate of the combustion air increases and the air-fuel mixture becomes difficult to ignite. On the other hand, when the regeneration process ends, the ECU 40 outputs a control signal to the switching valve 39 indicating that the switching valve opening / closing process is ended and the switching valve 39 is kept closed.

Next, the procedure of the switching valve opening / closing process executed by the ECU 40 will be described with reference to FIG.
As shown in FIG. 2, the ECU 40 first acquires the intake air amount Q based on the detection signal from the intake air amount sensor 44 (step S11). Subsequently, the ECU 40 determines whether or not the acquired intake air amount Q is equal to or less than a preset threshold value Qt (step S12).

  When the intake air amount Q is equal to or less than the threshold value Qt (step S12: YES), the ECU 40 controls the switching valve 39 to be closed (step S13), and temporarily ends the switching valve opening / closing process. On the other hand, when the intake air amount Q exceeds the threshold value Qt (step S12: NO), the ECU 40 controls the switching valve 39 to be in an open state (step S14), and temporarily ends the switching valve opening / closing process.

  Next, the operation of the burner 15 having the above-described configuration will be described with reference to FIG. FIG. 3 is a graph showing the relationship between the intake air amount Q and the air amount q of the combustion air supplied from the supply port 31, where the switching valve opening / closing process is executed in the burner 15. The comparative example which is a case where the example which is is a solid line and the switching valve 39 is always maintained in an open state is shown by a two-dot chain line. That is, the comparative example is the burner 15 placed under substantially the same condition as the burner for the exhaust gas purification apparatus that does not have the partition wall 25, the branch pipe 38, and the switching valve 39. Also, the lower limit air amount qmin shown in FIG. 3 is the amount of air in which oxygen shortage occurs near the ignition point 23 and the air-fuel mixture becomes difficult to ignite. Similarly, the upper limit air amount qmax shown in FIG. This is the amount of air that makes the air-fuel mixture difficult to ignite due to an increase in the air flow rate.

  In the embodiment, since the switching valve 39 is maintained in the closed state when the intake air amount Q is equal to or less than the threshold value Qt, the combustion region 20 is used for combustion only from the supply port 31 of the supply port 31 and the diversion port 32. Air is supplied. For this reason, in the range where the intake air amount Q is equal to or less than the threshold value Qt, the combustion air supplied from the supply port 31 is more in the embodiment than in the comparative example.

  Therefore, as shown in FIG. 3, in the comparative example, when the intake air amount Q is less than the intake air amount Qb less than the threshold value Qt, oxygen shortage near the ignition point 23 occurs and the air-fuel mixture becomes difficult to ignite. On the other hand, in the embodiment, in the range where the intake air amount Q is less than the intake air amount Qa which is smaller than the intake air amount Qb, oxygen shortage near the ignition point 23 occurs and the air-fuel mixture becomes difficult to ignite.

  On the other hand, in the embodiment, the switching valve 39 is maintained in the open state in a range where the intake air amount Q exceeds the threshold value Qt. That is, in the range where the intake air amount Q exceeds the threshold value Qt, the burner 15 of the example and the burner of the comparative example are in the same state. Therefore, in the embodiment, as in the comparative example, the ignitability of the air-fuel mixture is maintained until the intake air amount Q becomes the intake air amount Qc. In FIG. 3, the example and the comparative example are shown adjacent to each other in the range from the threshold value Qt to the intake air amount Qc.

  That is, in the comparative example, the air-fuel mixture can be ignited in the range A1 from the intake air amount Qb to the intake air amount Q. On the other hand, in the embodiment, the air-fuel mixture can be ignited in the range A2 of the intake air amount Q to the intake air amount Q smaller than the intake air amount Q. That is, in the embodiment, the range of the intake air amount Q that can ignite the air-fuel mixture is expanded more than the comparative example in the range where the intake air amount Q is equal to or less than the threshold value Qt. Improves.

  Further, the supply port 31 is formed closer to the bottom wall 17 side of the flame holder 16 than the ignition point 23 in the small diameter portion 18. According to such a configuration, the combustion air supplied from the supply port 31 to the combustion region 20 is higher than when the supply port 31 is formed closer to the ejection port 16A of the flame stabilizer 16 than the ignition point 23. Passes the ignition point 23 under probability. As a result, even when the amount of intake air supplied to the first chamber 26 is small, oxygen shortage near the ignition point can be suppressed.

  By the way, the flame F ejected from the small diameter portion 18 is expanded at the large diameter portion 19. The flame F contains unburned fuel. If such unburned fuel is mixed with the exhaust gas without being burned, more fuel is required for the regeneration process. In the burner 15 described above, the diversion port 32 is formed in the large diameter portion 19 of the flame holder 16. Therefore, compared with the case where the diversion port 32 is formed in the small diameter portion 18, the unburned fuel and the combustion air included in the flame F are easily mixed. As a result, since the unburned fuel contained in the flame F is reduced, the fuel necessary for the regeneration process can be reduced.

  Further, in the burner 15 described above, the total opening area of the diversion port 32 is larger than the total of the total opening area of the supply port 31. Therefore, for example, when the switching valve 39 is open, that is, when the intake air amount Q exceeds the threshold value Qt, compared with the case where the total opening area is equal at the supply port 31 and the diversion port 32, Air flow rate is reduced. As a result, since the intake air amount Q that realizes the upper limit air amount qmax increases, the burner 15 described above can cope with a larger intake air amount Q.

  In the burner 15 described above, the ECU 40 controls opening and closing of the switching valve 39 according to the intake air amount Q detected by the intake air amount sensor 44. Therefore, compared with the case where the switching valve 39 is a differential pressure valve that opens and closes based on, for example, a pressure difference between the upstream side and the downstream side of the switching valve 39 in the shunt pipe 38, the switching valve 39 corresponds to the amount of air supplied to the combustion region 20. The switching valve 39 can be opened and closed with high reliability.

As explained above, according to the burner 15 of the said embodiment, the effect enumerated below can be acquired.
(1) In the burner 15, the ignitability of the air-fuel mixture is maintained in the range A2 between the intake air amount Qa smaller than the intake air amount Qb and the intake air amount Qc. That is, the range of the intake air amount Q in which the ignitability of the air-fuel mixture is maintained is expanded as compared with a burner that does not have the partition wall 25, the branch pipe 38, and the switching valve 39. As a result, the ignitability of the air-fuel mixture can be improved.
(2) Since the air-fuel mixture is ignited even with a small intake air amount Q, the flame holder 16 can be downsized and the burner 15 can be downsized.

  (3) In the burner 15, the supply port 31 is formed in the small diameter portion 18 on the bottom wall 17 side of the flame holder 16 with respect to the ignition point 23. Therefore, the probability that the combustion air that has flowed into the combustion region 20 from the supply port 31 passes near the ignition point 23 can be increased. As a result, oxygen shortage near the ignition point 23 can be suppressed even if the intake air amount Q decreases.

  (4) In the burner 15, the diversion port 32 is formed in the large diameter portion 19. Therefore, the unburned fuel contained in the flame F and the combustion air are easily mixed. As a result, the unburned fuel contained in the flame F is reduced, and the fuel required for the regeneration process can be reduced.

  (5) In the burner 15, the total opening area of the diversion port 32 is larger than the total opening area of the supply port 31. Therefore, when the switching valve 39 is in the open state, the flow velocity of the combustion air in the vicinity of the ignition point 23 can be suppressed, so that a larger intake air amount Q can be handled.

  (6) In the burner 15, the opening and closing of the switching valve 39 is controlled by the ECU 40. Therefore, the switching valve 39 can be opened and closed according to the amount of air supplied to the combustion region 20 with high reliability.

In addition, the said embodiment can also be suitably changed and implemented as follows.
The burner for the exhaust purification device is a first pipe connected to the flame holder 16 in a state where the supply passage is an exhaust pipe through which exhaust from the engine flows and communicates with the combustion region 20, and the distribution flow The second pipe connected to the flame holder 16 in a state where the path is connected to the first pipe and communicates with the combustion region 20 may be used.

-Moreover, in the case of the structure mentioned above, the three-way valve arrange | positioned at the connection part of 1st piping and 2nd piping may be sufficient as a switching valve.
If the total opening area of the diversion port 32 is larger than the total opening area of the supply port 31, the opening area of one supply port 31 and one diversion port 32 may be changed as appropriate, or the supply port 31 and the diversion flow The number of the mouths 32 may be changed as appropriate.

In addition, the total opening area of the diversion port 32 may be smaller than the total opening area of the supply port 31.
The diversion port 32 may be an opening that communicates with the combustion region 20 on the side of the ejection port 16A of the flame stabilizer 16 relative to the ignition point 23, and may be formed in, for example, the small-diameter portion 18 or, for example, the small-diameter portion 18 and the large diameter part 19 may be formed.

  The flame holder 16 is not limited to a cylindrical shape provided with the small-diameter portion 18 and the large-diameter portion 19 and expanded toward the ejection port 16A, and may be, for example, a cylindrical shape in which the large-diameter portion 19 is omitted. In short, any cylindrical shape having the ejection port 16A may be used.

The supply port 31 is not limited to the opening facing the combustion region 20 on the bottom wall 17 side of the flame stabilizer 16 than the ignition point 23, and may be an opening facing the ignition point 23, for example.
In addition, the supply port may have an opening facing the combustion region 20 on the bottom wall 17 side of the flame holder 16 with respect to the ignition point 23 and an opening facing the ignition point 23, for example. In other words, the supply port may be an opening formed at a different position in the axial direction of the small diameter portion 18.

  The ECU 40 sets the opening degree of the switching valve 39 so that the flow rate of the combustion air near the ignition point 23 becomes a flow rate suitable for ignition of the air-fuel mixture according to the intake air amount Q detected by the intake air amount sensor 44. You may adjust. In this configuration, for example, an opening degree map that associates the intake air amount Q and the opening degree of the switching valve 39 is stored in the ECU 40 in advance, and the switching valve 39 is based on the intake air amount and the opening degree map. This is realized by controlling the opening degree.

  The ECU 40 may be electrically connected to a sensor for detecting the air amount in the air supply pipe 36 instead of the intake air amount sensor 44 for detecting the intake air amount in the intake pipe 35.

  The switching unit may be, for example, a differential pressure valve that operates based on a pressure difference between the external air pressure and the exhaust pressure in the air supply pipe 36 downstream from the air valve 37. With such a configuration, it is possible to switch between the cutoff state and the diversion state without being controlled by the ECU 40.

  The fuel injected from the fuel injection valve 21 may be supplied from a common rail instead of the fuel pump. A fuel pump that supplies fuel only to the fuel injection valve 21 may be mounted.

The fuel supply unit is not limited to the fuel injection valve 21 that injects the fuel into the combustion region, and may be, for example, a unit that supplies fuel vaporized in advance to the combustion region 20.
The ignition of the air-fuel mixture is not limited to an ignition plug, and may be performed by a glow heater, a laser ignition device, or a plasma ignition device. In addition, one of these may ignite the air-fuel mixture, or two or more of these may ignite the air-fuel mixture.

  The combustion air is not limited to the intake air flowing through the intake pipe 35, but may be air flowing through a pipe connected to the brake air tank, or air supplied by a blower dedicated to the exhaust purification device burner.

-The engine on which the burner for the exhaust gas purification apparatus is mounted may be a gasoline engine.
The temperature increase of the exhaust gas by the exhaust gas purification device burner is not limited to the regeneration process of the DPF 12, and may be used for the temperature increase of the catalyst.

  A1, A2 ... range, Q, Qa, Qb, Qc ... intake air amount, Qt ... threshold, q ... air amount, qmax ... upper limit air amount, qmin ... lower limit air amount, F ... flame, 10 ... exhaust purification device, 11 DESCRIPTION OF SYMBOLS ... Exhaust pipe, 12 ... DPF, 15 ... Exhaust purifier burner, 16 ... Flame stabilizer, 16A ... Outlet, 17 ... Bottom wall, 18 ... Small diameter part, 19 ... Large diameter part, 20 ... Combustion area, 21 DESCRIPTION OF SYMBOLS ... Fuel injection valve, 22 ... Spark plug, 22a ... Ignition part, 23 ... Ignition point, 24 ... Outer cylinder, 25 ... Partition wall, 26 ... 1st chamber, 27 ... 2nd chamber, 31 ... Supply port, 32 ... Splitting port 35 ... intake pipe, 36 ... air supply pipe, 37 ... air valve, 38 ... shunt pipe, 39 ... switching valve, 40 ... ECU, 41 ... upstream exhaust flow sensor, 42 ... downstream exhaust flow sensor, 43 ... temperature Sensor, 44 ... intake air amount sensor.

Claims (5)

A cylindrical flame holder having a jet port from which a combustion gas obtained by burning a mixture of fuel and air is jetted;
An igniter disposed in a combustion region in the flame holder to ignite the mixture;
A supply passage having a supply port opening in the combustion region and supplying air from the supply port to the combustion region, the supply passage communicating with an intake pipe through which air taken in by the engine flows ;
A diversion passage that is connected in the middle of the supply passage and has a diversion opening that opens to the combustion region, and supplies a part of the air in the supply passage from the diversion port to the combustion region,
The diversion port is disposed at a position closer to the ejection port than the supply port and the ignition unit,
A switching unit for switching between a shut-off state where a part of the air in the supply passage is not shunted to the shunt passage and a shunt state where the air is shunted;
The switching unit is
An intake air amount sensor for detecting an intake air amount of the engine;
A switching valve for switching the supply passage and the diversion passage to a non-communication state or a communication state;
A control unit for controlling the opening of the switching valve,
The controller is
When the intake air amount detected by the intake air amount sensor is less than or equal to a threshold value, the shutoff state is selected by controlling the switching valve to be closed ,
The burner for an exhaust gas purification apparatus, wherein the diversion state is selected by controlling the switching valve to open when the intake air amount detected by the intake air amount sensor exceeds the threshold value. The ignition part is
The burner for an exhaust gas purification apparatus according to claim 1, wherein the burner is disposed between a portion facing the supply port and a portion facing the diversion port in the combustion region. The flame holder is
A cylindrical portion surrounding the combustion region;
The cylindrical portion is
Expanded toward the spout,
A small diameter part surrounding the ignition part and formed with the supply port;
The burner for an exhaust gas purification apparatus according to claim 2, further comprising a large-diameter portion in which the diversion port is formed. In the flame holder, a plurality of the supply ports and a plurality of the diversion ports are formed,
The burner for an exhaust gas purification apparatus according to any one of claims 1 to 3, wherein a total opening area of the plurality of diversion ports is larger than a total opening area of the plurality of supply ports. The flame holder is
An inner cylinder that is a cylinder surrounding the combustion region;
An outer cylinder that surrounds the inner cylinder, and a gap between the inner cylinder and the inner cylinder is closed at both ends of the inner cylinder;
A partition wall that partitions the gap between the inner cylinder and the outer cylinder into a first chamber and a second chamber;
The supply port is formed in a part constituting the first chamber of the inner cylinder,
The diversion port is formed in a portion constituting the second chamber of the inner cylinder,
The supply passage includes the first chamber,
The diversion passage includes the second chamber,
The diversion passage is
A pipe communicating the first chamber and the second chamber on the outer peripheral surface of the outer cylinder;
The burner for an exhaust gas purification apparatus according to any one of claims 1 to 4, further comprising a switching valve that is disposed in the pipe and switches between communication and non-communication between the first chamber and the second chamber.

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