JP2011021549A - Diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement the regeneration processing of a DPF without a need of a compressor for combustion air supply. <P>SOLUTION: A throttle valve 5 is provided to an intake flow passage 4 of an engine body 1. A burner 8 for DPF regeneration processing is provided at the upstream side position of an installed position of the DPF 7 in an exhaust gas flow passage 6. A bypass line 12 branched from the upstream side position of an installed location of the throttle valve 5 in the intake flow passage 4 is connected to the combustor 9 of the burner 8. When regeneration processing of the DPF 7 is performed, an air 13 of which pressure is increased within the intake flow passage 4 on the upstream side by throttling the throttle valve 5 is guided through the bypass line 12 to the combustor 9 of the burner 8 serving as a combustion air. Thereby the burner 8 is operated, and a temperature of the DPF 7 is increased by a high-temperature combustion gas 18 produced by the burner 8, and thus deposited PM is burnt and removed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a diesel engine provided with a diesel particulate filter (DPF) and a regeneration burner in an exhaust gas flow path.

  Particulate matter (Particulate Matter, hereinafter referred to as PM) is included in the exhaust gas of a diesel engine, and suspended particulate matter such as PM is subject to environmental standards.

  Therefore, in a diesel engine, a diesel particulate filter (hereinafter referred to as DPF) is provided in the middle of the exhaust flow path, and PM contained in the exhaust gas is collected to purify the exhaust gas in the atmosphere. Measures are being taken to reduce the amount of PM discharged into the plant.

  By the way, the function of the DPF is basically such that PM in the exhaust gas is trapped and trapped. Therefore, when the collected PM accumulates and causes clogging, pressure loss is reduced. As a result, the engine performance may be deteriorated.

  In addition, since the exhaust temperature becomes high in high-speed and high-load operation, the PM collected in the DPF is reburned, so there is no possibility of clogging, but the exhaust temperature is low such as at low speed or low load. Under such operating conditions, clogging is likely to occur. Therefore, it is necessary to perform a regeneration process in which the temperature of the DPF is positively increased and the PM deposited on the DPF is forcibly burned and removed.

  One of the methods for regenerating the DPF is generated by burning the fuel in the burner with a configuration in which a burner is installed at a location upstream of the DPF installation location in the exhaust passage of the diesel engine. Conventionally, a technique has been proposed in which a high-temperature combustion gas is introduced to the DPF so that the DPF is heated to a required temperature and the accumulated PM is burned and removed (for example, Patent Documents). 1).

  In recent years, in diesel engines, when the amount of fuel injection is small, such as when the load is low, the amount of air drawn into the engine is limited, leading to a gas processing device provided in an exhaust gas flow path such as a DPF. A configuration in which a throttle valve is provided in the intake passage for the purpose of improving engine performance by maintaining a high exhaust temperature or adjusting the exhaust gas circulation rate when performing exhaust gas recirculation (EGR). And that is getting done.

JP-A-8-260944

  However, as shown in Patent Document 1, when a DPF regeneration burner is provided at a position upstream of the DPF installation location in the exhaust gas flow path of a diesel engine, fuel is supplied by the burner combustor. In actuality, it is necessary to supply combustion air (oxygen) for combustion, and therefore, it is necessary to equip the burner with a compressor as a supply device for combustion air.

  Therefore, the manufacturing cost of the diesel engine increases, and power for driving the compressor is required, so that the fuel consumption of the diesel engine is reduced by the amount of power consumed to drive the compressor. It's real.

  Therefore, the present invention can supply combustion air to the burner for regenerating the DPF provided in the exhaust gas flow path without requiring power, and can reduce costs. An object of the present invention is to provide a diesel engine that can improve fuel consumption.

  In order to solve the above problems, the present invention provides a diesel engine having a DPF in an exhaust gas passage of an engine body, and a throttle valve in the intake passage of the engine body, corresponding to claim 1, A burner for DPF regeneration processing is provided at the upstream position of the DPF installation location in the exhaust gas flow path, and a bypass line branched from the upstream position of the throttle valve installation location in the intake flow path is connected to the burner. The configuration is as follows.

  In the above configuration, an opening / closing valve is provided in a bypass line that is branched from the upstream side position of the throttle valve in the intake passage and connected to the burner.

According to the diesel engine of the present invention, the following excellent effects are exhibited.
(1) In a diesel engine having a DPF in the exhaust gas passage of the engine body, a throttle valve is provided in the intake passage of the engine body, and a DPF regeneration process is performed at a position upstream of the DPF installation location in the exhaust gas passage. A bypass line branched from the upstream side position of the throttle valve in the intake passage is connected to the burner, so that the throttle valve can be installed by restricting the throttle valve. Since the air whose pressure is increased in the intake flow path upstream from the location can be guided as combustion air to the DPF regeneration burner provided in the exhaust gas flow path through the bypass line, the DPF It is not necessary to separately provide a compressor for supplying combustion air to the regeneration burner.
(2) Therefore, the cost required for the diesel engine of the present invention can be reduced, and the power for driving the compressor for supplying combustion air is not required, so that an effect of improving fuel consumption is expected. it can.
(3) By providing an open / close valve in the bypass line that branches off from the upstream position of the throttle valve in the intake flow path and is connected to the burner, it is provided on the bypass line during normal operation. By closing the open / close valve, it is possible to prevent the phenomenon that air is blown through the bypass line between the intake passage and the burner provided in the exhaust gas passage, or the exhaust gas flows backward. The operation of the main body can be controlled more accurately.

It is a schematic diagram which shows the normal driving | running state in one Embodiment of the diesel engine of this invention. It is a schematic diagram which shows the regeneration process state of DPF by the diesel engine of FIG. It is a schematic diagram which shows the other form of implementation of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  1 and 2 show an embodiment of a diesel engine of the present invention, which has the following configuration.

  That is, the throttle valve 5 is provided in the middle of the intake passage 4 connected to the intake port 2 of the engine body 1.

  On the other hand, a DPF 7 is provided in the middle of the exhaust gas passage 6 connected to the exhaust port 3 of the engine body 1.

  Further, a DPF regeneration burner 8 provided with a combustor 9, a fuel injection device 10, and an ignition device 11 is provided at a position upstream of a required amount of the DPF 7 in the exhaust gas flow path 6, and The bypass line 12 branched from the position immediately upstream of the installation location of the throttle valve 5 in the intake passage 4 is connected to the combustor 9 of the burner 8. As a result, the throttle valve 5 is throttled as shown in FIG. 2 (not fully closed), so that the air 13 whose pressure is increased in the upstream portion of the installation location of the throttle valve 5 in the intake flow path 4 is generated. The burner 8 can be led to the combustor 9 through the bypass line 12.

  The fuel injection amount when burning the burner 8 for the regeneration process of the DPF 7 may be about several percent of the fuel injection amount when the engine body 1 is operated. Considering the amount of combustion air and the pressure of the air 13 that is increased in the upstream portion of the intake flow path 4 from the place where the throttle valve 5 is installed by restricting the throttle valve 5, the pressure is increased. So that the air 13 in the state can be guided by an amount commensurate with the required air amount during combustion of the burner 8, What is necessary is just to set it so that it may become about several percent.

  Reference numeral 14 denotes a fuel injection device installed in the engine body 1, 15 denotes an intake valve, and 16 denotes an exhaust valve. Reference numeral 17 denotes exhaust gas discharged from the engine body 1.

  When the diesel engine of the present invention having the above-described configuration is used, the throttle valve 5 in the intake passage 4 is normally opened as shown in FIG. As a result, almost all of the air 13 flowing through the intake passage 4 is supplied to the engine body 1 via the intake port 2 and the engine body 1 is operated.

  The exhaust gas 17 generated by the operation of the engine main body 1 is guided from the exhaust port 3 to the DPF 7 through the exhaust gas flow path 6, and PM is collected and purified by the DPF 7.

  Since the bypass line 12 communicates the intake passage 4 and the combustor 9 of the burner 8 provided in the exhaust gas passage 6, the intake passage 4 when the throttle valve 5 is opened. Is higher than the pressure of the exhaust gas passage 6, the air 13 flows from the intake passage 4 to the exhaust gas passage 6 through the bypass line 12. In this case, the bypass line 12 is used. Is set to a small flow passage cross-sectional area of several percent of the flow passage cross-sectional area of the intake flow passage 4 and the throttle valve 5 is in an open state, so that the pressure in the intake flow passage 4 is Since it is relatively low, even if the air 13 blows through the bypass line 12 to the exhaust gas flow path 6 side, it is only a small amount, and there is no possibility of particularly affecting the operation of the engine body 1.

  On the other hand, when the pressure of the exhaust gas passage 6 increases due to the DPF 7 tending to be clogged while the throttle valve 5 is in the open state, the pressure of the exhaust gas passage 6 is changed to the intake passage 4. In this case, the exhaust gas 17 flows backward from the exhaust gas passage 6 through the bypass line 12 to the intake passage 4. However, even in this case, the bypass line 12 is set to have a small flow path cross-sectional area of about several percent of the cross-sectional area of the intake flow path 4, and thus flows back to the intake flow path 4 side. Since the exhaust gas 17 is a small amount and does not significantly increase the amount of exhaust gas circulated by the exhaust gas recirculation that is generally performed, there is no possibility of particularly affecting the operation of the engine body 1.

  In the diesel engine of the present invention, when the regeneration process of the DPF 7 on which PM is accumulated by performing the collection process of the PM (not shown) in the exhaust gas 17 for a required time, the intake air flow as shown in FIG. The throttle valve 5 on the road 4 is throttled. As a result, the pressure of the air 13 in the upstream portion of the installation location of the throttle valve 5 in the intake flow path 4 increases, so that the increased air 13 passes through the bypass line 12 in the exhaust gas flow path 6. It is guided to the combustor 9 of the burner 8 provided at a position upstream of the DPF 7. Therefore, in this state, the burner 8 injects a required amount of fuel from the fuel injection device 10 and operates the ignition device 11, so that the fuel injected from the fuel injection device 10 is burned by the burner 8. The fresh air 13 guided from the intake passage 4 through the bypass line 12 is burned as combustion air. Therefore, the high-temperature combustion gas 18 generated by this combustion is guided to the DPF 7 through the exhaust gas flow path 6, so that the DPF 7 is heated and the accumulated PM is removed by combustion.

  When the burner 8 is combusted, the amount of fuel injected from the fuel injection device 10 becomes excessive with respect to the amount of air 13 guided from the intake passage 4 through the bypass line 12. However, when the unburned fuel is led to the DPF 7 through the exhaust gas flow path 6, it is burned like catalytic combustion and used to raise the temperature of the DPF 7, so that any functional problem may occur. There is no.

  As described above, according to the diesel engine of the present invention, the DPF regeneration processing provided at the upstream side of the DPF 7 in the exhaust gas flow path 6 can be performed only by the throttle valve 5 provided in the intake flow path 4 being throttled. Therefore, it is not necessary to separately provide a compressor for supplying combustion air to the burner 8.

  Therefore, it is possible to reduce the cost required for the diesel engine of the present invention and to improve the fuel efficiency of the diesel engine of the present invention because the power for driving the compressor for supplying the combustion air is not necessary. Is possible.

  In the above description, the throttle valve 5 of the intake passage 4 is throttled when the regeneration process of the DPF 7 is performed. However, the air sucked into the engine body 1 when the fuel injection amount is small, such as at low load. By limiting the amount, the intake air is used for the purpose of improving the engine performance such as maintaining the temperature of the exhaust gas 17 high or adjusting the exhaust gas circulation amount when performing exhaust gas recirculation (EGR). The regeneration of the DPF 7 may be performed by starting the operation of the burner 8 for the DPF regeneration process in accordance with the operation of reducing the throttle valve 5 of the flow path 4.

  Further, in the above description, it has been described that when the throttle valve 5 is throttled, the combustion of the DPF regeneration burner 8 is started. However, in general, a diesel engine burns fuel under excessive air conditions. In view of the fact that the exhaust gas 17 contains sufficient oxygen, a DPF regeneration burner 8 provided in the exhaust gas passage 6 of the diesel engine of the present invention having the above-described configuration is injected into the fuel. The fuel is injected at a smaller injection amount than that of the apparatus 10 by using oxygen contained in the exhaust gas 17 flowing through the exhaust gas passage 6 so that the fuel is always operated, and the throttle valve 5 is operated. When the fuel injection device 10 is throttled, the amount of fuel injected from the fuel injection device 10 is increased, and the fuel with the increased injection amount is sucked through the bypass line 12. The air 13 is led from the channel 4 may be caused to burn as co fuel-air vapor.

  Next, FIG. 3 shows an application example of the embodiment of FIGS. 1 and 2 as another embodiment of the present invention. In the configuration similar to that shown in FIGS. The on / off valve 19 is provided.

  Other configurations are the same as those shown in FIGS. 1 and 2, and the same components are denoted by the same reference numerals.

  According to the diesel engine of the present embodiment, during normal operation, the opening / closing valve 19 provided on the bypass line 12 is closed to provide the intake passage 4 and the exhaust gas passage 6. Since the phenomenon that the air 13 blows through the bypass line 12 and the exhaust gas 17 flows backward from the combustor 9 of the burner 8 for DPF regeneration processing does not occur, the operation of the engine body 1 is controlled more accurately. Is possible.

  When the regeneration process of the DPF 7 is performed, the throttle valve 5 in the intake passage 4 is throttled in the same manner as shown in FIG. 2 with the on-off valve 19 on the bypass line 12 being opened. By introducing the air 13 whose pressure is increased in the upstream portion of the installation location of the throttle valve 5 to the combustor 9 of the burner 8 through the bypass line 12, and starting the operation of the burner 8 using the air 13 as combustion air, The temperature of the DPF 7 is raised by the high-temperature combustion gas 18 (see FIG. 2) generated in the burner 8, and the accumulated PM can be removed by combustion.

  Therefore, according to the present embodiment, the same effect as that of the embodiment of FIGS. 1 and 2 can be obtained.

  The present invention is not limited to the above embodiment, and the shape and size of the combustor 9 of the burner 8 provided in the exhaust gas passage 6 may be changed as appropriate. Further, the shape, size, and mounting position of the fuel injection device 10 and the ignition device 11 may be appropriately changed according to the shape and size of the combustor 9.

  The diesel engine of the present invention may be applied to any type as long as it is a diesel engine equipped with a DPF.

  Of course, various modifications can be made without departing from the scope of the present invention.

1 Engine body 4 Intake passage 5 Throttle valve 6 Exhaust gas passage 7 DPF
8 Burner 12 Bypass line 13 Air 19 On-off valve

Claims (2)

  In a diesel engine provided with a DPF in the exhaust gas passage of the engine body, a throttle valve is provided in the intake passage of the engine body, and a DPF regeneration burner is positioned upstream of the DPF installation location in the exhaust gas passage. A diesel engine having a configuration in which a bypass line branched from an upstream position of a throttle valve installation location in the intake flow path is connected to the burner.   The diesel engine according to claim 1, wherein an opening / closing valve is provided in a bypass line branched from the upstream side position of the throttle valve in the intake passage and connected to the burner.

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