JP2010106680A - Method and device for operating particulate filter regeneration burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for operating a particulate filter regeneration burner materializing stable combustion by improving atomization of fuel and stably regenerating a particulate filter. <P>SOLUTION: When a flow rate of exhaust gas G is small, a fuel valve 9 is opened and closed by outputting an opening/closing signal 9a to the fuel valve 9 from a control device 33, and fuel is intermittently injected from the fuel injection nozzle 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

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. The present invention relates to a method and an apparatus for operating a particulate filter regeneration burner applicable to the apparatus.

  In general, a diesel engine as an internal combustion engine does not perform spark ignition by a plug, unlike a gasoline engine, and directly ignites light oil as fuel directly into air heated to high compression.

  The exhaust gas discharged from the diesel engine contains particulate matter (Particulate Matter), which is composed of soot made of carbonaceous matter and high-boiling hydrocarbon components. SOF (Soluble Organic Fraction: Soluble Organic Fraction) is the main component, and further contains a trace amount of sulfate (mist-like sulfuric acid component), but as a measure to reduce this type of particulates, Conventionally, a particulate filter is provided in the middle of an exhaust pipe through which exhaust gas from a diesel engine flows.

  The particulate filter has a porous honeycomb structure made of a ceramic such as cordierite, and the inlets of the respective flow paths partitioned in a lattice pattern are alternately sealed, and the flow paths in which the inlets are not sealed The outlet thereof is sealed, and only the exhaust gas that has permeated through the porous thin wall partitioning each flow path is discharged downstream.

  By the way, the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, so that the particulate filter is appropriately burned and removed before the exhaust resistance increases due to clogging, so that the particulate filter can be regenerated. However, depending on the operating condition of the diesel engine, an exhaust temperature that is high enough to cause the particulates to self-combust may not be obtained. If the collected amount exceeds the amount, and thus the operation state with such a low exhaust temperature continues, the particulate filter does not proceed well and the particulate filter is over-collected. There is a risk of falling.

  Therefore, at the stage where the accumulated amount of particulates on the particulate filter has increased, the temperature of the exhaust gas is raised by performing post injection in addition to normal fuel injection in a diesel engine, and the temperature of the particulate filter is changed to a regeneration temperature (for example, It is considered to perform forced regeneration by burning the particulates by raising the temperature to about 630 ° C. or higher.

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

  Therefore, conventionally, in order to raise the exhaust gas temperature to a certain temperature or more, a particulate filter regeneration burner having a fuel injection nozzle and a discharge terminal as an ignition means is disposed upstream of the particulate filter, and the particulate filter By injecting fuel from the fuel injection nozzle of the filter regeneration burner, igniting and burning at the discharge terminal, and generating a flame, the exhaust gas introduced into the particulate filter is forcibly heated, and the temperature of the particulate filter is raised to the regeneration temperature. It is considered to regenerate the particulate filter by burning the particulates collected by the particulate filter.

For example, Patent Literature 1 shows a general technical level related to the particulate filter regeneration burner as described above.
JP-A-8-260944

  However, in the conventional particulate filter regeneration burner as described above, under the conditions where the engine speed is low and the exhaust gas flow rate is small, the amount of fuel burned by the particulate filter regeneration burner is small, and the fuel flow rate injected from the fuel injection nozzle is small. Since it is very small (for example, about 19 [cc / min] or less), fuel atomization failure may occur, and stable combustion may not be realized.

  In view of such circumstances, the present invention provides a particulate filter regeneration burner operating method and apparatus that can improve atomization of fuel, realize stable combustion, and stably regenerate the particulate filter. It is what.

The present invention relates to a particulate filter that raises the temperature of a particulate filter by injecting fuel from a fuel injection nozzle to the upstream side of the particulate filter that collects particulates in exhaust gas discharged from an internal combustion engine and performing ignition combustion. An operation method of the curate filter regeneration burner,
The present invention relates to an operating method of a particulate filter regeneration burner characterized in that fuel is intermittently injected from the fuel injection nozzle when the flow rate of exhaust gas is small.

  Under the condition where the exhaust gas flow rate is low, the amount of fuel burned by the particulate filter regeneration burner is small and the fuel flow rate injected from the fuel injection nozzle is very small. When the fuel is intermittently injected from the nozzle, the fuel flow rate at the time of fuel injection increases, so that fuel atomization failure does not occur and stable combustion can be realized.

  In the operation method of the particulate filter regeneration burner, the fuel can be intermittently injected when the flow rate of the exhaust gas is not more than half of the rated exhaust gas flow rate.

On the other hand, the present invention includes a fuel injection nozzle that injects fuel upstream of a particulate filter that collects particulates in exhaust gas discharged from an internal combustion engine;
Ignition means for igniting and burning the fuel injected from the fuel injection nozzle;
An injection pump for pumping fuel to the fuel injection nozzle;
A fuel valve capable of shutting off fuel pumped from the injection pump to the fuel injection nozzle;
And a controller for outputting an opening / closing signal to the fuel valve so that fuel is intermittently injected from the fuel injection nozzle when the flow rate of the exhaust gas is small. It is such a thing.

  When configured as described above, when the flow rate of the exhaust gas is small, the fuel valve is opened and closed by an open / close signal output from the control device to the fuel valve, and fuel is intermittently injected from the fuel injection nozzle. Since the fuel flow rate at the time of fuel injection increases, fuel atomization defects do not occur, and stable combustion can be realized.

  In the operating device for the particulate filter regeneration burner, the control device can be configured such that an open / close signal is output to the fuel valve when the flow rate of the exhaust gas is less than half of the rated exhaust gas flow rate.

  In the operating device for the particulate filter regeneration burner, a heat equalizing member can be arranged in the middle of the exhaust passage between the fuel injection nozzle and the particulate filter. Even if a change occurs in the temperature of the exhaust gas that is forcibly heated as the fuel is intermittently injected, the temperature change of the exhaust gas is mitigated by passing the exhaust gas through the heat equalizing member. Therefore, the particulate filter can be prevented from being partially melted at a high temperature.

  According to the operation method and apparatus of the particulate filter regeneration burner of the present invention, it is possible to improve the atomization of the fuel, realize stable combustion, and achieve the excellent effect that the regeneration of the particulate filter can be performed stably. obtain.

  Embodiments of the present invention will be described below with reference to the accompanying 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 a 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. About the flow path, the exit is sealed, and the particulates in the exhaust gas G discharged | emitted from the diesel engine 1 are collected by the inner surface of a porous thin wall, and each flow path is divided. Only the exhaust gas G that has permeated through the porous thin wall is discharged to the downstream side.

  At the center position of the filter case 2 upstream of the particulate filter 3 (upper side in FIG. 1), a fuel injection nozzle 4 for injecting fuel toward the particulate filter 3 on the downstream side is provided, and the fuel injection nozzle 4 A discharge terminal 5 (ignition means) for igniting and burning fuel by electric discharge is provided in the vicinity of the tip of the first electrode.

  Further, 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, and the fuel from the fuel supply pump 7 is further supplied. A part of is supplied to the fuel injection nozzle 4 via a high-pressure injection pump 8 and a fuel valve 9.

  Inside the upstream end (upper end) of the filter case 2 is provided 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. On the downstream side (lower side) of the chamber 12, there is provided a dilution chamber 15 that forms a cylindrical dilution chamber 13 and is provided with a dilution opening 14 for injecting exhaust gas G on the inner peripheral surface of the downstream side. is there.

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

  Further, an upstream side (above) of the particulate filter 3, that is, in the middle of the exhaust passage between the fuel injection nozzle 4 and the particulate filter 3, is a uniform material made of a refractory porous material for making the exhaust gas temperature uniform. A thermal member 17 is provided.

  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 supplied 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 led to the particulate filter 3 through the inside of the gas and the exhaust gas G bypasses the fuel injection nozzle 4 and is led to the particulate filter 3 through the dilution chamber 13 and the dilution opening 14 of the dilution chamber 15. A bifurcated branch portion is formed in the bypass flow path 22 as described above. 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 flows to the bypass flow path 22, and the exhaust gas G is regenerated when the particulate filter 3 is regenerated. A damper 23 is provided which operates so that a part thereof is guided to the combustion gas passage 21. A flow path switching valve may be used in place 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 may be 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. good.

  Further, an air supply device 25 is connected to the combustion gas flow path 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, 25 'is 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 the oxygen concentration of the exhaust gas G whose oxygen concentration has decreased due to combustion of the diesel engine 1 is injected from the fuel injection nozzle 4. One that can supply air 24 in an amount that can be increased to a concentration that can stably burn the fuel to be used.

  In FIG. 1, reference numeral 33 denotes a control device (ECU), to which a rotation speed signal 34 and a throttle opening signal 35 detected in the diesel engine 1 are input. A differential pressure signal 37 from a differential pressure gauge 36 that detects a pressure difference before and after the particulate filter 3 is input, and the control device 33 measures the accumulation state of particulates in the particulate filter 3 based on the differential pressure signal 37. It is like that.

  The control device 33 outputs a signal 23a for operating the damper 23 so as to close the combustion gas flow path 21 at normal times, whereby all the exhaust gas G is diverted from the dilution chamber 15 through the bypass flow path 22. The particulates are collected by being supplied to 13 and guided to the particulate filter 3 through the dilution opening 14.

  Further, the control device 33, when it is measured by the differential pressure signal 37 from the differential pressure gauge 36 that particulates have accumulated on the particulate filter 3 and the exhaust resistance has increased due to clogging, A signal 23a for operating the damper 23 to output a part of the exhaust gas G to the combustion gas flow path 21 is output, and a signal 25a for operating the air supply device 25 is output to output the air 24 for the combustion. The gas is supplied to the gas flow path 21, and the signal 9a for opening the fuel valve 9 is output while the signal 8a for operating the high-pressure injection pump 8 is output, the fuel is supplied to the fuel injection nozzle 4, and the discharge is performed. A signal 5a for igniting is output from the terminal 5 (ignition means). Thereby, the flame F by the burner device 18 is formed, and this flame F heats the exhaust gas G supplied to the dilution chamber 13 by the bypass passage 22 and ejected from the dilution opening 14, and the heated exhaust gas. The temperature of G is equalized by the heat equalizing member 17 and supplied to the particulate filter 3, and the particulates deposited on the particulate filter 3 are burned and removed to regenerate the particulate filter 3. ing.

  However, in the case of the illustrated example, when the engine speed is low and the flow rate of the exhaust gas G is small (for example, when the flow rate of the exhaust gas G is less than half of the rated exhaust gas flow rate), the control device 33 sends the fuel valve 9 to the fuel valve 9. An open / close signal 9a is output to open / close the fuel valve 9 so that fuel is intermittently injected from the fuel injection nozzle 4.

  Next, the operation of the illustrated example will be described.

  At normal times, the control device 33 outputs a signal 23 a for operating the damper 23 so as to close the combustion gas flow path 21, whereby all exhaust gas G is supplied to the dilution chamber 13 of the dilution chamber 15 by the bypass flow path 22. Then, the particulates are collected by being guided to the particulate filter 3 through the dilution opening 14.

  When particulates accumulate on the particulate filter 3, it is measured by the differential pressure signal 37 from the differential pressure gauge 36 that the exhaust resistance is increased due to clogging, and a part of the exhaust gas G is removed from the control device 33. A signal 23 a for operating the damper 23 to be supplied to the combustion gas flow path 21 is output, and a signal 25 a for operating the air supply device 25 is output to supply air 24 to the combustion gas flow path 21. Further, a signal 8a for opening the fuel valve 9 is output while a signal 8a for operating the high-pressure injection pump 8 is output, fuel is supplied to the fuel injection nozzle 4, and ignition is performed by the discharge terminal 5 (ignition means). A signal 5a for performing is output. Thereby, a flame F is formed by the burner device 18, and the exhaust gas G supplied to the dilution chamber 13 by the bypass flow path 22 and ejected from the dilution opening 14 is heated by the flame F, and the heated exhaust gas G However, since the temperature is equalized by the heat equalizing member 17 and supplied to the particulate filter 3, the particulates accumulated on the particulate filter 3 are 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 is low depending on the operation state of the diesel engine 1. Even if the situation 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, and accordingly, the particulate filter 3 Can always be reproduced stably.

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

  Further, in the air supply device 25, the amount of the exhaust gas G guided from the combustion gas flow path 21 to the burner device 18 is insufficient with respect 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.

  Furthermore, 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, and then the bypass passage 22 enters the dilution chamber 13. By mixing the supplied exhaust gas G and performing slow combustion, it is possible to prevent a problem that a local high temperature portion is generated.

  Moreover, in the case of the illustrated example, when the engine speed is low and the flow rate of the exhaust gas G is small (for example, when the flow rate of the exhaust gas G is less than half of the rated exhaust gas flow rate), the control device 33 supplies the fuel valve 9. An opening / closing signal 9a is output, the fuel valve 9 is opened / closed, fuel is intermittently injected from the fuel injection nozzle 4, and the fuel flow rate during one fuel injection is about 20 [cc / min]. Therefore, the fuel atomization failure does not occur, and stable combustion can be realized.

  Further, in the case of the illustrated example, a heat equalizing member 17 such as a refractory porous material for equalizing the exhaust gas temperature is disposed in the middle of the exhaust passage between the fuel injection nozzle 4 and the particulate filter 3. Therefore, even if a change occurs in the exhaust gas G temperature that is forcibly heated as fuel is intermittently injected from the fuel injection nozzle 4, the exhaust gas G passes through the soaking member 17, Since the temperature change of the exhaust gas G is relaxed and introduced into the particulate filter 3, it is possible to avoid the particulate filter 3 from being partially melted at a high temperature.

  Thus, the atomization of the fuel can be improved, stable combustion can be realized, and the particulate filter 3 can be stably regenerated.

  The operation method and apparatus of the particulate filter regeneration burner according to the present invention are not limited to the above illustrated examples, and various changes can be made without departing from the scope of the present invention. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole schematic block diagram which shows an example of the form which implements this invention.

Explanation of symbols

1 Diesel engine (internal combustion engine)
3 Particulate filter 4 Fuel injection nozzle 5 Discharge terminal (ignition means)
8 Injection Pump 9 Fuel Valve 9a Signal 18 Burner Device 19 Particulate Filter Regeneration Burner 20 Exhaust Pipe 21 Combustion Gas Channel 22 Bypass Channel G Exhaust Gas

Claims (5)

A particulate filter regeneration burner that raises the temperature of the particulate filter by injecting fuel from a fuel injection nozzle to the upstream side of the particulate filter that collects particulates in the exhaust gas discharged from the internal combustion engine and igniting combustion. Driving method,
A method of operating a particulate filter regeneration burner, characterized in that fuel is intermittently injected from the fuel injection nozzle when the flow rate of exhaust gas is small.   The method of operating a particulate filter regeneration burner according to claim 1, wherein the fuel is intermittently injected when the flow rate of the exhaust gas is less than half of the rated exhaust gas flow rate. A fuel injection nozzle that injects fuel upstream of a particulate filter that collects particulates in exhaust gas discharged from the internal combustion engine;
Ignition means for igniting and burning the fuel injected from the fuel injection nozzle;
An injection pump for pumping fuel to the fuel injection nozzle;
A fuel valve capable of shutting off fuel pumped from the injection pump to the fuel injection nozzle;
And a control device that outputs an open / close signal to the fuel valve so that fuel is intermittently injected from the fuel injection nozzle when the flow rate of the exhaust gas is small.   The operating device of the particulate filter regeneration burner according to claim 3, wherein the control device is configured to output an opening / closing signal to the fuel valve when the flow rate of the exhaust gas is less than half of the rated exhaust gas flow rate.   The operating device for a particulate filter regeneration burner according to claim 3 or 4, wherein a heat equalizing member is disposed in the middle of an exhaust passage between the fuel injection nozzle and the particulate filter.

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