JP4487912B2 - Fuel addition device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel addition device for an internal combustion engine provided with a fuel addition valve for adding fuel to an exhaust passage or the like.

As a fuel addition device for an internal combustion engine for adding fuel to an exhaust passage, fuel remaining in the fuel passage is introduced by introducing compressed air into the fuel passage in the fuel addition valve immediately after the fuel is injected from the fuel addition valve. Or the apparatus which blows off the particulate adhering to an injection port is proposed (refer patent document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.
JP 2004-263661 A JP 2001-73744 A JP 2000-54833 A

  The fuel remaining in the fuel passage inside the fuel addition valve becomes tarized or carbonized when the ambient temperature reaches approximately 150 ° C. or more, and becomes a deposit. When deposit is generated in the fuel passage, the fuel passage is clogged, and it becomes difficult to add a predetermined amount of fuel to the exhaust passage. The deposit once generated is difficult to remove, and in order to remove the deposit, for example, it is necessary to raise the temperature around the deposit to a high temperature (approximately 650 ° C.) to burn the deposit. However, when the fuel addition valve is provided in the exhaust passage, the installation location may be set at a relatively low temperature position in the exhaust passage in order to suppress carbonization of the attached fuel. In this case, it is difficult to raise the temperature around the fuel passage, and the deposit generated in the fuel passage may not be burned sufficiently. The technology described in the above-mentioned prior art document aims to remove the fuel remaining in the fuel passage of the fuel addition valve or the particulate adhering to the injection port to suppress the generation of the deposit. It is not aimed at removal.

  Therefore, an object of the present invention is to provide a fuel addition device for an internal combustion engine that can efficiently remove deposits generated in a fuel passage.

A fuel addition apparatus for an internal combustion engine according to the present invention includes a fuel addition valve for adding fuel introduced into an internal fuel passage from an injection port at the tip of the fuel passage, and an ozone supply means for supplying ozone into the fuel passage. Determining means for determining the degree of clogging of the fuel passage due to deposit, and ozone supply control means for controlling the supply of ozone from the ozone supply means to the fuel passage based on the determination result of the determination means. By providing, the above-described problem is solved (claim 1).

According to the fuel addition apparatus of the present invention, by supplying ozone to the inside of the fuel passage of the fuel addition valve, the deposit generated inside the fuel passage or around the injection port is utilized by utilizing the strong oxidizing action of ozone. It can be burned and removed efficiently. Oxidation effect of ozone is sufficiently exerted even at a temperature range of about 100 ° C or lower, so even if the fuel addition valve is arranged in a relatively low temperature part in the exhaust passage, the deposit is sufficiently removed can do. Further, according to the fuel addition device of the present invention, by controlling the supply of ozone according to the degree of clogging due to the fuel passage deposit, it is possible to use ozone without excess or deficiency, thereby reducing the amount of ozone consumed. Clogging due to can be reliably eliminated.

  In one embodiment of the present invention, the fuel addition valve is provided with an ozone passage that merges with the fuel passage inside the fuel addition valve, and the ozone supply means supplies ozone to the fuel passage through the ozone passage. You may supply (Claim 2).

  According to the above aspect, ozone supplied from the ozone supply means can be intensively introduced into the fuel passage via the ozone passage, and can flow from the fuel passage to the injection port. This makes it possible to supply ozone so as to aim at the deposit formed inside the fuel passage, and to invade deep into the fuel passage from the injection port, or to reliably burn the carbonized ozone inside the fuel passage. it can. Since ozone can be intensively supplied to the inside of the fuel passage, it is difficult for ozone to be wasted, and a high deposit removing action can be produced with a small amount of ozone. Ozone can be guided to the fuel passage inside the fuel addition valve without touching the atmosphere of the place where the fuel addition valve is installed. Thereby, it is possible to suppress the ozone consumption due to the dilution of ozone with the gas around the fuel addition valve or the reaction with the reducing agent such as HC, and to efficiently exhibit the oxidizing action of ozone.

In one form of this invention, the said fuel addition valve may be provided so that the said fuel may be added with respect to an exhaust passage ( Claim 3 ). According to this embodiment, it is possible to provide an effective solution for clogging of the fuel addition valve in the exhaust passage where deposits are particularly likely to occur. Deposits can be efficiently removed with a small amount of ozone by suppressing ozone consumption due to dilution of ozone by exhaust and reaction with a reducing agent such as HC contained in the exhaust.

Further, in a mode in which the fuel addition valve adds fuel to the exhaust passage, the ozone supply control means is configured to perform the idling operation of the internal combustion engine when the degree of clogging determined by the determination means has reached a predetermined limit. Alternatively, ozone may be supplied from the ozone supply means to the fuel passage on the condition that it is immediately after stopping ( Claim 4 ).

  When the internal combustion engine is idling or just after it is stopped, the exhaust flow rate and pressure in the exhaust passage of the internal combustion engine are small, so the amount of ozone required for deposit removal also decreases. For this reason, it is possible to further reduce the amount of ozone used by supplying ozone at the timing during idle operation or immediately after stopping. In addition, at the timing during idle operation or immediately after stopping, ozone dilution due to exhaust or ozone consumption due to reaction with a reducing agent can be further suppressed, and thereby the oxidizing action of ozone can be more efficiently exhibited.

In one embodiment of the present invention including the ozone supply control means, the discrimination means can determine the degree of clogging due to deposit by various methods. As an example, the determination unit may determine the clogging based on a physical quantity that changes in correlation with fuel addition from the fuel addition valve to the exhaust passage ( claim 5 ). For example, when fuel is added to the exhaust passage, the air-fuel ratio of the exhaust changes as the fuel is added. Therefore, the correlation between the fuel addition amount instructed to the fuel addition valve and the corresponding change in the air-fuel ratio. From the relationship, it can be determined whether or not the amount of fuel instructed from the fuel addition valve has been added. If the amount of fuel is insufficient, it can be determined that clogging has progressed. Alternatively, when the temperature of the catalyst or filter in the exhaust passage is increased by fuel addition from the fuel addition valve, the fuel addition valve is determined from the correlation between the fuel addition amount instructed to the fuel addition valve and the temperature rise of the catalyst or the like. It can be determined whether or not the amount of fuel instructed is added, and if the amount of fuel is insufficient, it can be determined that clogging is progressing.

As another example of determining the degree of clogging, the determination means is based on a specific parameter having a correlation with a deposit amount in the fuel passage among parameters for controlling the operating state of the internal combustion engine. The degree of clogging may be determined ( Claim 6 ). For example, using the accelerator pedal depression amount and engine speed as specific parameters, it is determined whether or not the internal combustion engine is being operated in a state where deposits are likely to occur, and when the engine is being operated in a state where deposits are likely to occur. The time can be integrated and the degree of clogging can be estimated from the integrated value.

  As described above, according to the fuel addition device of the present invention, it is generated inside the fuel passage or around the injection port by utilizing the strong oxidizing action of ozone supplied inside the fuel passage of the fuel addition valve. The deposited deposit can be burned and removed efficiently.

  FIG. 1 shows an embodiment in which the fuel addition apparatus of the present invention is applied to an exhaust system of a diesel engine (hereinafter abbreviated as an engine) 1 as an example of an internal combustion engine. The engine 1 is mounted on a vehicle as a driving power source, and an intake passage 3 and an exhaust passage 4 are connected to the cylinder 2 thereof. The intake passage 3 is provided with a throttle valve 5 for adjusting the amount of intake air, a compressor 6a and an intercooler 7 for the turbocharger 6, and the exhaust passage 4 is provided with a turbine 6b for the turbocharger 6. A fuel addition valve 8 for adding fuel as a reducing agent to the exhaust passage 4 is provided upstream of the turbine 6b in the exhaust passage 4, and an occlusion reduction type NOx catalyst is provided downstream of the turbine 6b in the exhaust passage 4. (Hereinafter abbreviated as catalyst) An exhaust purification unit 10 including 9 is provided. Further, an A / F sensor 11 that detects the air-fuel ratio of the exhaust gas is provided downstream of the turbine 6 b in the exhaust passage 4 and upstream of the exhaust purification unit 10. The exhaust passage 4 and the intake passage 3 are connected by an EGR passage 12, and an EGR cooler 13 and an EGR valve 14 are provided in the EGR passage 12. The engine 1 also includes an injector 15 for injecting fuel into the cylinder 2, a common rail 16 that stores high-pressure fuel to be injected from the injector 15, and fuel from the fuel tank (not shown) to the common rail 16 and the fuel addition valve 8. And a supply pump 17 to be supplied.

  An ozone supply device (ozone supply means) 18 is connected to the fuel addition valve 8. The ozone supply device 18 includes an ozone generator 19 that generates ozone, an air pump 20 that supplies air to the ozone generator 19, and an ozone supply pipe 21 that guides ozone generated by the ozone generator 19 to the fuel addition valve 8. And an open / close valve 22 that opens and closes the ozone supply pipe 21. The ozone generator 19 includes an AC power supply 22 and a plurality of electrodes 24, and converts oxygen in the air supplied from the air pump 20 into ozone using means such as corona discharge and ultraviolet irradiation. Supply of ozone from the ozone supply device 18 is controlled by an engine control unit (ECU) 25. The ECU 25 includes various sensors such as a crank angle sensor (not shown) that outputs a signal corresponding to the rotation speed of the crankshaft, an air flow meter (not shown) that detects the intake air amount, and the A / F sensor 11 provided in the exhaust passage. A computer unit for operating the control target equipment such as the fuel addition valve 8, the injector 15, and the pressure adjustment valve (not shown) for the common rail 16 based on the determination result. is there. As an example, the ECU 15 injects fuel from the fuel addition valve 8 at an appropriate timing for a short time to create a rich spike state in which the amount of fuel is larger than the stoichiometric air-fuel ratio, and to the catalyst of the exhaust purification unit 10. A process of releasing the stored NOx is executed. These treatments may be the same as those of a known exhaust purification device. Furthermore, the ECU 15 functions as a determination unit and an ozone supply control unit of the present invention by repeatedly executing the routine shown in FIG. 3 at a predetermined cycle. Details of this routine will be described later.

  As shown in FIG. 2, the fuel addition valve 8 includes a valve main body 26 having a hollow cylindrical valve chamber 27 and a needle 28 as a valve body inserted into the valve chamber 27. The needle 28 is reciprocated in the vertical direction of the fuel addition valve 8 (vertical direction in FIG. 2) by an electromagnetic force generated by an electromagnetic coil (not shown) disposed on the upper portion of the fuel addition valve 8. When the needle 28 is driven to the distal end side (the lower end side in FIG. 2) of the valve body 26, the distal end portion 28a of the needle 28 comes into close contact with the valve seat 29, and the valve chamber 27 is closed to the downstream side. Is driven backward (upper end in FIG. 2), the distal end portion 28a of the needle 28 is separated from the valve seat 29, thereby opening the valve chamber 27 to the downstream side. A fuel passage 30 that opens to the tip of the valve body 26 is provided on the downstream side of the valve seat 27. As shown by an arrow F in FIG. 2, the fuel flowing into the valve chamber 27 is injected into the exhaust passage 4 from the injection port 30a at the tip of the fuel passage 30 when the valve chamber 27 is opened to the downstream side. Alternatively, it is added.

  The valve body 26 has one end 31a opened to the outer surface 26a of the valve body 26 and the other end 31b in the middle of the fuel passage 30, more specifically, a section sandwiched between the injection port 30a and the valve seat 29 (see FIG. 2, and more preferably, an ozone passage 31 that joins the upstream side (valve seat 29 side) of the section is provided. Between the injection port 30a and the valve seat 29 is a place where deposits are most likely to occur. One end 31 a of the ozone passage 31 is connected to the ozone supply pipe 21. Thereby, the ozone supplied from the ozone supply device 18 is guided to the inside of the fuel passage 30 without touching the exhaust of the exhaust passage 4 as shown by the arrow A direction.

  Next, the ozone supply control routine of FIG. 3 will be described. In this ozone supply control routine, the ECU 25 first determines whether or not an ozone supply condition for supplying ozone to the fuel passage 30 is satisfied in step S11. The ozone supply condition is a condition set to determine whether or not the degree of clogging of the fuel passage 30 due to deposit exceeds a predetermined limit that requires removal of deposit by supplying ozone. For example, the degree of clogging due to deposit can be determined based on the change in the air-fuel ratio detected by the A / F sensor 11 before and after the addition operation of the fuel addition valve 8. That is, when fuel is added to the exhaust passage 4 from the fuel addition valve 8, the air-fuel ratio in the exhaust passage 4 changes to the rich side according to the amount of addition. However, when the fuel passage 30 is clogged, only a small amount of fuel is added to the fuel addition amount command value for the fuel addition valve 8, or no fuel is added at all. The air-fuel ratio of the exhaust gas detected by the sensor 11 is biased toward the lean side (the side with the smaller fuel amount) than the target air-fuel ratio at the time of fuel addition. The degree of clogging of the fuel passage 30 is determined from the degree of the deviation, and when the degree exceeds a predetermined limit, it can be determined that the ozone supply condition is satisfied.

  When it is determined in step S11 that the ozone supply condition is satisfied, the ECU 25 proceeds to step S12, and determines whether or not the engine 1 is idling or just after the engine 1 is stopped. For example, it can be determined that the engine 1 is idling when the engine 1 is in a predetermined idling engine speed range and the accelerator opening is 0%, that is, the accelerator pedal is not depressed. Whether or not the engine 1 has just stopped is determined to be immediately after the stop when the elapsed time from the time when it is determined that the engine 1 has stopped is within a predetermined range, or when the engine water temperature is within a predetermined temperature range. be able to. In the case where a temperature sensor is provided in the exhaust passage 4, it may be determined whether or not the engine 1 has just stopped using the temperature detected by the temperature sensor. The stop of the engine 1 can be determined, for example, based on whether or not the rotation speed of the crankshaft is zero. Alternatively, it may be determined that the engine 1 is stopped when the stop condition of the engine 1 is established in the idle stop control.

  When it is determined that the engine 1 is idling or immediately after the engine 1 is stopped, the ECU 25 proceeds to step S13 and opens the on-off valve 22 to supply ozone to the fuel passage 30. Thereafter, the current ozone supply control routine is terminated. If it is determined in step S11 that the ozone supply condition is not satisfied, or if it is determined in step S12 that the engine 1 is not idling or just after stopping, the ECU 25 proceeds to step S14. Then, the on-off valve 22 is closed to finish the current ozone supply control routine.

  According to the fuel addition device of the above form, when the degree of clogging due to the deposit in the fuel passage 30 exceeds a predetermined limit and the engine 1 is idling or immediately after being stopped, the fuel supply valve is supplied from the ozone supply device 18. Ozone is supplied to the eight ozone passages 31. Since ozone has a strong oxidizing action even in a temperature range of 100 ° C. or less, the deposit adhering to the inside of the fuel passage 30 or in the vicinity of the injection port 30a is burned with the ozone and efficiently removed to the outside of the fuel addition valve 8. can do. Even if the fuel addition valve 8 is disposed in a relatively low temperature region in the exhaust passage 4, the deposit removing action is sufficiently exhibited. Since the clogging of the fuel addition valve 8 can be reliably eliminated, various processes realized by adding fuel to the exhaust passage 4, such as a process of releasing NOx occluded in the catalyst, a sulfur coverage of the catalyst, The exhaust gas purification function of the exhaust gas purification unit 10 can be maintained by reliably performing a regeneration process for recovering the poison or a process for burning the particulates accumulated on the particulate filter.

  In the fuel addition device of this embodiment, an ozone passage 31 that joins the fuel passage 30 inside the fuel addition valve 8 is provided in the valve body 26, and ozone is supplied from the ozone supply device 18 to the ozone passage 31. Therefore, ozone generated by the ozone supply device 18 can be intensively introduced into the fuel passage 30 to flow ozone from the upstream side of the fuel passage 30 to the injection port 30a. Accordingly, ozone is supplied so as to aim at the deposit formed in the fuel passage 30 and the ozone that has penetrated from the injection port 30a into the fuel passage 30 or has been carbonized inside the fuel passage 30 is ensured. Can be burned. Therefore, a high deposit removing action can be produced with a small amount of ozone. Consumption of ozone because there is no fear that ozone is consumed by dilution before contact with the exhaust gas before being supplied to the fuel passage 30 or that ozone is consumed by a reducing agent such as HC, CO, NO in the exhaust gas. Can be further reduced. Since the fuel addition valve 8 is also used as a valve for supplying ozone in the vicinity of the injection port 30a, the cost is higher than in the case where an addition valve for supplying ozone in the vicinity of the injection port 30a is provided in the exhaust passage 4. Can be reduced.

  Further, in the fuel addition device of this embodiment, when the degree of clogging of the fuel passage 30 does not exceed a predetermined limit, the on-off valve 22 is closed and the supply of ozone is stopped, so that wasteful consumption of ozone is suppressed. be able to. Further, when the degree of clogging of the fuel passage 30 exceeds a predetermined limit, ozone is supplied at the timing when the engine 1 with a small exhaust flow rate and pressure is idling or immediately after the stop, so the amount of ozone used Can be further reduced.

  In the above embodiment, the ECU 25 functions as a determination unit by executing step S11 of FIG. 3, and the ozone supply control unit is executed by the ECU 25 executing steps S12 and S13 or step S14 according to the determination result of step S11. Function as.

  The present invention is not limited to the above-described form and may be implemented in various forms. For example, the degree of clogging of the fuel passage 30 due to the deposit is not limited to the above-described form, and can be determined by various methods. As an example, the degree of clogging can be determined based on various physical quantities that change in correlation with fuel addition from the fuel addition valve 8 to the exhaust passage 4. The air-fuel ratio described above is a kind of physical quantity, but a physical quantity other than the air-fuel ratio can also be used. For example, when fuel is added from the fuel addition valve 8 in order to regenerate the function by raising the temperature of the exhaust purification unit 10, it is between the amount of fuel added to the fuel addition valve 8 and the temperature rise of the exhaust purification unit 10. Therefore, it is determined whether or not the fuel of the value commanded from the fuel addition valve 8 is added using the temperature of the unit 10 as a physical quantity, and if the fuel addition quantity is insufficient It can be determined that clogging is progressing. Further, the degree of clogging of the fuel passage 30 can also be determined by the change in fuel pressure when the fuel addition valve 8 performs the fuel addition operation.

  Alternatively, the degree of clogging is determined using a specific parameter having a correlation with the amount of deposit accumulated in the fuel passage 30 among parameters acquired or monitored by the ECU 25 to control the operating state of the engine 1. You can also For example, whether or not the engine 1 is operating in a region where deposits are likely to occur is determined from specific operation control parameters of the engine 1 (for example, the amount of depression of the accelerator pedal and the engine speed), and in regions where deposits are likely to occur. The time determined to be in operation can be integrated and the degree of clogging can be determined from the integrated value.

  In the above embodiment, it is determined that the ozone supply condition is satisfied only when the degree of clogging of the fuel passage 30 due to deposit exceeds a predetermined limit, and ozone supply is permitted. It is not restricted to this aspect. For example, a flow rate adjustment valve may be provided in place of the on-off valve 22, and the ozone supply amount may be increased or decreased according to the degree of clogging due to deposit.

  The present invention is not limited to a diesel engine, and may be applied to various internal combustion engines that use gasoline or other fuels. The fuel addition valve is not limited to the above-described form, and various types of fuel addition valves may be provided. In the above embodiment, the ozone passage 31 is joined to the fuel passage 30 at a position close to the valve seat 29 of the fuel passage 30, but if the deposit generated inside the fuel passage 30 can be removed, You may change a supply position suitably. Further, even in a mode in which ozone is supplied from the outside of the fuel addition valve 8 toward the injection port 30a, it is included in the scope of the present invention as long as ozone can be introduced into the fuel passage 30 to remove deposits. It is. The present invention is not limited to a fuel addition device that adds fuel to the exhaust passage, and the fuel addition valve may be provided at a location other than the exhaust passage as long as deposits can be generated in the fuel passage. Further, in the present invention, the term “fuel addition” includes various modes as long as fuel is added, and is a concept including modes such as fuel injection, spraying, and spraying.

The figure which shows the diesel engine in which the fuel addition apparatus which concerns on this invention was integrated in the exhaust system. Sectional drawing of the fuel addition valve provided in the fuel addition apparatus. The flowchart which shows the ozone supply control routine which ECU of FIG. 1 performs.

Explanation of symbols

1 Diesel engine (internal combustion engine)
4 Exhaust passage 8 Fuel addition valve 18 Ozone supply device (ozone supply means)
25 ECU (determination means, ozone supply control means)
30 Fuel passage 30a Injection port

Claims (6)

A fuel addition valve for adding fuel guided to an internal fuel passage from an injection port at the tip of the fuel passage, an ozone supply means for supplying ozone into the fuel passage, and a clogging condition due to deposits in the fuel passage. A fuel for an internal combustion engine , comprising: a determination unit that determines; and an ozone supply control unit that controls supply of ozone from the ozone supply unit to the fuel passage based on a determination result of the determination unit. Addition equipment.   The fuel addition valve is provided with an ozone passage that merges with the fuel passage inside the fuel addition valve, and the ozone supply means supplies ozone to the fuel passage through the ozone passage. The fuel addition apparatus according to claim 1. The fuel addition apparatus according to claim 1 or 2, wherein the fuel addition valve is provided so as to add the fuel to an exhaust passage. When the degree of clogging determined by the determination unit has reached a predetermined limit, the ozone supply control unit is configured to leave the fuel passage from the ozone supply unit on condition that the internal combustion engine is idling or immediately after being stopped. The fuel addition device according to claim 3 , wherein ozone is supplied to the fuel. 3. The fuel addition apparatus according to claim 1 , wherein the determination unit determines the clogging based on a physical quantity that changes in correlation with fuel addition from the fuel addition valve. The discrimination means discriminates the degree of clogging based on a specific parameter having a correlation with a deposit amount in the fuel passage among parameters for controlling an operating state of the internal combustion engine. The fuel addition apparatus according to claim 1 or 2 .

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