JP5304177B2 - Exhaust purification device - Google Patents

Description

  The present invention relates to a diesel engine, particularly a diesel engine that is used under severe conditions such as for agriculture, etc., and is capable of purifying exhaust gas at low cost with simple control without providing an advanced control device. It relates to the device.

  Conventionally, in order to purify particulate matter (particulate matter) discharged from a diesel engine, a DPF (diesel particulate filter) is installed in the exhaust pipe of the diesel engine, and such particulates. Particulates are collected by a filter. The particulate filter has a porous honeycomb structure made of ceramics such as cordierite, and the inlets of each flow path partitioned in a lattice pattern are alternately sealed, and the flow paths in which the inlets are not sealed The outlet is sealed, and only the exhaust gas that has permeated through the porous thin wall defining each flow path is discharged downstream, while the particulates in the exhaust gas are porous. It is collected on the inner surface of the thin wall.

  Particulates in the exhaust gas discharged from the diesel engine are collected and deposited on the inner surface of the porous thin wall, so that the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. It is necessary to regenerate the particulate filter, but depending on the operating condition of the diesel engine, the exhaust temperature may not be high enough to cause the particulates to self-combust.For this reason, in the operating region where the exhaust temperature is low If the collected amount exceeds the particulate regeneration amount, and the exhaust gas temperature continues to operate at such a low exhaust temperature, regeneration of the particulate filter does not proceed satisfactorily. May fall into an overcollected state.

  Therefore, at the stage where the accumulated amount of particulates on the particulate filter has increased, the exhaust gas temperature is increased by performing post injection in addition to normal fuel injection in the diesel engine, and the temperature of the particulate filter is changed to the regeneration temperature ( For example, it is considered to perform forced regeneration by burning the particulates by increasing the temperature to about 330 ° C. or higher.

  However, this method requires very complicated control, and therefore there is a problem that the control device becomes expensive.

  For this reason, a burner device is provided in front of the particulate filter, and when the accumulated amount of particulates on the particulate filter has increased, fuel is burned by the burner device to raise the temperature of the particulate filter to the regeneration temperature. It has been considered to perform forced regeneration by burning particulates.

As prior art document information related to a technique for regenerating a particulate filter using this type of burner device, there is Patent Document 1 below.
JP-A-8-260944

  However, when the fuel is simply injected into the exhaust gas from the diesel engine and burned, the oxygen concentration of the exhaust gas is low and the combustion becomes unstable. There is a problem that may not be done.

  On the other hand, as shown in Patent Document 1, in a burner apparatus that supplies fuel and combustion air, it is necessary to supply the burner apparatus with an amount of air that can completely burn the supplied fuel. This is because when air is insufficient, soot is generated and a new problem occurs. Therefore, in Patent Document 1, it is necessary to supply a large amount of air for complete combustion in the burner device. For this reason, it is necessary to provide a large air pump. Such a large air pump is mounted on a diesel engine. Difficult to do.

  In addition, as described above, when complete combustion is performed by the burner device, the flame temperature becomes remarkably high, and when the high-temperature flame is led to the particulate filter, the heat resistance of the cordierite is increased. When the temperature (about 1450 ° C.) is exceeded, there is a problem that the particulate filter burns out locally.

  The present invention has been made in view of the above-described circumstances, and enables stable combustion in the burner device with a small amount of air supply so that the particulate filter can be reliably regenerated, and the flame of the burner device can be used locally. An object of the present invention is to provide an exhaust emission control device capable of preventing the occurrence of a typical high temperature part and maintaining the soundness of the particulate filter.

The present invention is an exhaust emission control device that includes a particulate filter in an exhaust pipe of an internal combustion engine, and a burner device that raises the temperature of the particulate filter by injecting and burning fuel upstream of the particulate filter. The exhaust pipe is provided with a combustion gas flow path for guiding the exhaust gas to the particulate filter via the burner device and a bypass flow path for guiding the exhaust gas to the particulate filter without going through the burner device. Connecting an air supply device for supplying air to the combustion gas flow path;
The burner device has a swirler that swirls and injects exhaust gas from the combustion gas flow path;
A battery charger provided in the internal combustion engine, wherein the air supply device includes a reciprocating compressor that reciprocates a piston by an electric motor to generate compressed air and an ejector that entrains air by the compressed air of the reciprocating compressor. The air pump can be driven by a power source of the exhaust gas , and the air pump is used for the amount of oxygen necessary for burning the fuel injected from the burner device by the exhaust gas guided from the combustion gas flow path to the burner device. We will supply only the shortage,
The present invention relates to an exhaust emission control device, characterized in that a heat equalizing member for heating exhaust gas to a uniform temperature is disposed at a front portion of the particulate filter.

  According to the above-described exhaust purification apparatus of the present invention, the combustion gas flow path that guides the exhaust gas to the particulate filter via the burner device, and the exhaust gas without passing through the burner device, to the exhaust pipe of the internal combustion engine Since a bypass flow path leading to the particulate filter is provided and an air supply device for supplying air to the combustion gas flow path is connected, even if the oxygen concentration in the exhaust gas is low due to the operating state of the internal combustion engine The fuel injected from the fuel injection nozzle can be stably and reliably burned by the exhaust gas from the combustion gas flow path to which air is supplied, so that the particulate filter can always be regenerated stably. is there.

  Since the exhaust gas introduced from the combustion gas flow path to the burner device is supplied by the air supply device, the amount of oxygen required to burn the fuel injected from the burner device is insufficient. There is an effect that the air supply device can be made small to supply a small amount of air.

  In addition, as described above, the exhaust gas supplied with air and the fuel injected from the fuel injection nozzle are mixed to perform slow combustion, and then the exhaust gas from the bypass passage is mixed to perform slow combustion. Therefore, it is possible to prevent a problem that a local high temperature part is generated, and thus to prevent a problem that the particulate filter is locally burned out.

  Further, since the burner device has a swirler that swirls and injects exhaust gas from the combustion gas flow path, there is an effect that the fuel injected from the burner device can be more stably and uniformly burned.

Further, as an air supply device, a reciprocating compressor that reciprocates a piston by an electric motor to generate compressed air, a reciprocating compressor that reciprocates a piston by an electric motor by the compressed air of the reciprocating compressor, and the reciprocating compressor And an air pump that is driven by a power source of a battery charger provided in the internal combustion engine. The air pump is connected to the combustion gas flow path. The exhaust gas introduced to the burner device supplies only the amount of oxygen necessary for burning the fuel injected from the burner device, so that the burner device can be operated by a small air supply device. Supply the shortage of oxygen required for fuel combustion Can, therefore, there is an effect of easily mounting the air supply system to the internal combustion engine.

  In addition, by arranging a heat equalizing member for heating the exhaust gas to a uniform temperature at the front part of the particulate filter, the temperature of the exhaust gas guided to the particulate filter can be made more uniform. There is an effect that the problem that the particulate filter is locally burned out can be prevented more reliably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a diesel engine (internal combustion engine), and 2 denotes a filter case in which a particulate filter 3 is housed. .

  The particulate filter 3 has a porous honeycomb structure made of ceramic such as cordierite, and the inlets of the respective flow paths partitioned in a lattice pattern are alternately sealed, and the inlets are not sealed. The outlet of the passage is sealed, and the particulates in the exhaust gas are collected on the inner surface of the porous thin wall, and the exhaust that permeates the porous thin wall that defines each flow path. Only gas is discharged downstream.

  Further, a fuel injection nozzle 4 for injecting fuel toward the particulate filter 3 on the rear side is provided at the center position of the filter case 2 upstream of the particulate filter 3 (upper side in FIG. 1). A discharge terminal 5 (ignition means) adapted to ignite the fuel by discharge is provided near the tip of the nozzle 4.

  The fuel in the fuel tank 6 in which the fuel made of light oil is stored is supplied to the engine pump of the diesel engine 1 by the low-pressure fuel supply pump 7. The unit is supplied to the fuel injection nozzle 4 via a high-pressure injection pump 8 and a fuel valve 9.

  Inside the front end (upper end) of the filter case 2 is provided with a front chamber 12 having a combustion gas introduction chamber 11 in which a combustion opening 10 surrounding the tip of the fuel injection nozzle 4 is formed. 12 is provided with a dilution chamber 15 which forms a cylindrical dilution chamber 13 and has a dilution opening 14 for injecting exhaust gas to the rear inner peripheral surface.

  Further, as shown in FIG. 2, the combustion opening 10 of the front chamber 12 is provided with a plurality of blades 16a so as to inject the exhaust gas G from around the fuel injection nozzle 4 with a swirl S (swirl) and inject it. The swirler 16 is provided.

  Furthermore, a soaking member 17 made of a porous material or the like for heating the exhaust gas to a uniform temperature is provided at the front part (upper part) of the particulate filter 3.

  The fuel injection nozzle 4, the discharge terminal 5, and the swirler 16 provided in the combustion gas introduction chamber 11 constitute a burner device 18, and further, the burner device 18, the dilution chamber 15, and the leveling device. A particulate filter regeneration burner 19 is constituted by the heat member 17.

  On the other hand, the exhaust pipe 20 for leading the exhaust gas G from the diesel engine 1 is diluted from the swirler 16 around the fuel injection nozzle 4 in the burner device 18 by supplying the exhaust gas G to the combustion gas introduction chamber 11. The combustion gas flow path 21 that is guided to the particulate filter 3 through the inside of the chamber 15 and the exhaust gas G are bypassed without passing through the fuel injection nozzle 4, and the dilution chamber 13 and the dilution opening 14 of the dilution chamber 15 are bypassed. A bifurcated branch portion is formed in the bypass flow path 22 that is led to the particulate filter 3. Further, at a branch portion of the combustion gas flow path 21 and the bypass flow path 22, the combustion gas flow path 21 is normally closed and the exhaust gas G is allowed to flow to the bypass flow path 22, and the exhaust gas is regenerated when the particulate filter 3 is regenerated. A damper 23 is provided that operates to guide a part of G to the combustion gas flow path 21. A flow path switching valve may be used instead of the damper 23, and the flow rate of the exhaust gas G guided to the combustion gas flow path 21 may be adjusted.

  Further, without providing the damper 23, the respective cross-sectional areas and the like are set in advance so that the exhaust gas G flows through the combustion gas passage 21 and the bypass passage 22 at a predetermined ratio. Also good.

  Further, an air supply device 25 is connected to the combustion gas passage 21 so as to increase the oxygen concentration in the exhaust gas G supplied to the combustion gas introduction chamber 11 by supplying air 24. . In FIG. 1, reference numeral 25 'denotes a check valve. The air supply device 25 can supply the air 24 having a pressure higher than the pressure of the exhaust gas G, and injects the oxygen concentration of the exhaust gas G whose oxygen concentration is reduced by the combustion of the diesel engine 1 from the fuel injection nozzle 4. What can supply the air 24 in an amount that can be increased to a concentration that can stably burn the fuel to be used.

  At this time, the air supply device 25 is preferably one that can be driven by a power source (for example, DC 12 V) of a battery charger provided in the diesel engine 1. For this reason, as a result of studying various pumps, the present inventors have connected a plurality of turbofans 26 (two in FIG. 3) in series and driven by the electric motor 27 as shown in FIG. It has been found that the air pump 28 can be used. According to the air pump 28, the air 24 can be supplied at a pressure that is small and higher than the pressure of the exhaust gas G, and the supply amount of the air 24 that can supply insufficient oxygen with respect to the oxygen amount necessary for the burner device 18 is secured. And can be easily mounted on the diesel engine 1.

  As shown in FIG. 4, the air supply device 25 includes a reciprocating compressor 30 that reciprocates a piston 29 by an electric motor (not shown) to generate compressed air, and air is compressed by compressed air from the reciprocating compressor 30. It has been found that an air pump 32 comprising an ejector 31 that is to be wound can be employed. The air pump 32 can also be small in size, can supply the air 24 while maintaining the pressure and supply amount, and can be easily mounted on the diesel engine 1.

  In FIG. 1, reference numeral 33 denotes a control device (ECU), to which a rotational speed signal 34 and a throttle opening signal 35 detected in the diesel engine 1 are input. Further, the particulate filter The differential pressure signal 37 from the differential pressure gauge 36 for detecting the pressure difference before and after 3 is input, and the control device 33 measures the particulate accumulation state in the particulate filter 3 by the differential pressure signal 37. Yes.

  Then, the control device 33 operates the damper 23 so as to close the combustion gas passage 21 at normal times, thereby supplying all the exhaust gas G to the dilution chamber 13 of the dilution chamber 15 through the bypass passage 22. The particulates are collected by being guided to the particulate filter 3 through the dilution opening 14.

  When particulates are deposited on the particulate filter 3, exhaust resistance increases due to clogging. Therefore, the control device 33 receiving the differential pressure signal 37 from the differential pressure gauge 36 does not supply particulates to the particulate filter 3. Measure curate deposition. When the accumulation of particulates is measured, the control device 33 operates the damper 23 so as to supply a part of the exhaust gas G to the combustion gas flow path 21 and operates the air supply device 25. The air 24 is supplied to the combustion gas flow path 21, the high-pressure injection pump 8 is operated, the fuel valve 9 is opened to supply fuel to the fuel injection nozzle 4, and the discharge terminal 5. Ignition is performed by (ignition means). Thereby, the flame F by the burner device 18 is formed, and further, this flame F is supplied to the dilution chamber 13 by the bypass flow path 22 and mixed with the exhaust gas G ejected from the dilution opening 14. The heat is uniformly heated by the heat equalizing member 17 and supplied to the particulate filter 3, whereby the particulate deposited on the particulate filter 3 is burned and removed to regenerate the particulate filter.

  The operation of the above embodiment will be described below.

  During normal operation of the exhaust gas purification apparatus of FIG. 1, the control device 33 operates the damper 23 so as to close the combustion gas flow path 21, whereby all the exhaust gas G is sent to the dilution chamber 15 by the bypass flow path 22. The particulates are collected by being supplied to the dilution chamber 13 and guided to the particulate filter 3 through the dilution opening 14. At this time, the exhaust gas G may flow through the combustion gas passage 21 and the bypass passage 22 at a predetermined ratio without providing the damper 23. However, when the damper 23 is not provided, the exhaust gas G always flows through the burner device 18, so that the fuel injection nozzle 4 is heated by the exhaust gas G and the fuel is coked in the fuel injection nozzle 4. Therefore, it is necessary to take measures to prevent this coking problem. However, as described above, the damper 23 is provided so that the exhaust gas G does not flow into the combustion gas passage 21 in the normal state. By doing so, it is preferable to prevent the problem of fuel coking in the fuel injection nozzle 4.

  When the particulates accumulate on the particulate filter 3, the control device 33 receiving the differential pressure signal 37 from the differential pressure gauge 36 measures the particulate accumulation on the particulate filter 3.

  When the accumulation of particulates is measured, the control device 33 operates the damper 23 and supplies the air supply device 25 so as to supply a part of the exhaust gas G to the combustion gas passage 21. Air 24 is supplied to the combustion gas passage 21, the high-pressure injection pump 8 is operated, the fuel valve 9 is opened to supply fuel to the fuel injection nozzle 4, and the discharge terminal 5 (ignition) Means). Thereby, the flame F by the burner apparatus 18 is formed.

  The flame F of the burner device 18 is mixed with the exhaust gas G supplied from the bypass flow path 22 to the dilution chamber 13 and ejected from the dilution opening 14, and is then uniformly heated by the heat equalizing member 17 to form the patties. Since the particulate filter 3 is supplied to the particulate filter 3, the particulate matter deposited on the particulate filter 3 is burned and removed, and the particulate filter 3 is regenerated.

  As described above, since the air 24 is supplied to the combustion gas passage 21 branched from the bypass passage 22 by the air supply device 25, the oxygen concentration in the exhaust gas G varies depending on the operation state of the diesel engine 1. Even if a low state occurs, the fuel injected from the fuel injection nozzle 4 can be stably and reliably burned by the exhaust gas G from the combustion gas flow path 21 to which the air 24 is supplied. The regeneration of the filter 3 can always be performed stably.

  At this time, since the burner device 18 has the swirler 16 that swirls and injects the exhaust gas G from the combustion gas flow path 21, the fuel injected from the burner device 18 is more stable and uniform. It will be burned.

  Further, in the air supply device 25, the exhaust gas G introduced from the combustion gas flow path 21 to the burner device 18 is insufficient relative to the amount of oxygen necessary for burning the fuel injected from the burner device 18. Therefore, the air supply device 25 can be made small to supply a small amount of air.

  Therefore, as shown in FIG. 3, the air supply device 25 includes an air pump 28 in which a plurality of turbo fans 26 are connected in series. Alternatively, as shown in FIG. 4, the reciprocating compressor 30 and the reciprocating compressor 30 By providing an air pump 32 including an ejector 31 that is operated by compressed air, for example, small air pumps 28 and 32 that can be driven by a power source (for example, DC 12V) of a battery charger provided in the diesel engine 1 can be employed. Therefore, the air supply device 25 can be mounted on the diesel engine 1.

  Further, as described above, the exhaust gas G supplied with the air 24 by the air supply device 25 and the fuel injected from the fuel injection nozzle 4 are mixed, so that slow combustion is performed. By mixing the exhaust gas G supplied to the chamber 13 and performing slow combustion, it is possible to prevent a problem that a local high temperature portion is generated. Further, since the heat equalizing member 17 for heating the exhaust gas G to a uniform temperature is disposed at the front part of the particulate filter 3, the temperature of the exhaust gas G guided to the particulate filter 3 is further uniformized. Will come to be. In this way, the temperature of the exhaust gas G is made uniform by the particulate filter regeneration burner 19 and is guided to the particulate filter 3, so that the problem that the particulate filter 3 is locally burned can be surely generated. Can be prevented.

  It should be noted that the exhaust emission control device of the present invention is not limited to the illustrated embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

1 is an overall schematic diagram illustrating an example of an embodiment for carrying out the present invention. It is a perspective view which shows an example of the swirler which comprises some burner apparatuses. It is the schematic which shows the reference example of the air supply apparatus used for the apparatus of this invention. It is the schematic which shows an example of the air supply apparatus used for the apparatus of this invention.

Explanation of symbols

1 Diesel engine (internal combustion engine)
DESCRIPTION OF SYMBOLS 3 Particulate filter 16 Swirler 17 Soaking | uniform-heating member 18 Burner apparatus 20 Exhaust pipe 21 Combustion gas flow path 22 Bypass flow path 24 Air 25 Air supply apparatus 26 Turbo fan 28 Air pump 30 Reciprocating compressor 31 Ejector 32 Air pump G Exhaust gas

Claims (1)

An exhaust gas purification apparatus comprising a burner device that includes a particulate filter in an exhaust pipe of an internal combustion engine and injects and burns fuel upstream of the particulate filter to raise the temperature of the particulate filter, A combustion gas flow path for guiding exhaust gas to the particulate filter via the burner device and a bypass flow path for guiding the exhaust gas to the particulate filter without passing through the burner device are provided in the pipe. Connect an air supply device that supplies air to the gas flow path,
The burner device has a swirler that swirls and injects exhaust gas from the combustion gas flow path;
A battery charger provided in the internal combustion engine, wherein the air supply device includes a reciprocating compressor that reciprocates a piston by an electric motor to generate compressed air , and an ejector that entrains air by the compressed air of the reciprocating compressor. The air pump can be driven by a power source of the exhaust gas , and the air pump is used for the amount of oxygen necessary for burning the fuel injected from the burner device by the exhaust gas guided from the combustion gas flow path to the burner device. We will supply only the shortage,
An exhaust gas purification apparatus comprising a heat equalizing member for heating the exhaust gas to a uniform temperature at a front portion of the particulate filter.

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