JP5532008B2 - Internal combustion engine - Google Patents

Internal combustion engine Download PDF

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JP5532008B2
JP5532008B2 JP2011092061A JP2011092061A JP5532008B2 JP 5532008 B2 JP5532008 B2 JP 5532008B2 JP 2011092061 A JP2011092061 A JP 2011092061A JP 2011092061 A JP2011092061 A JP 2011092061A JP 5532008 B2 JP5532008 B2 JP 5532008B2
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fuel
injection valve
liquid
fuel injection
injected
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JP2012225214A (en
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覚 佐々木
卓政 横田
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株式会社デンソー
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M25/00Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/022Adding fuel and water emulsion, water or steam
    • F02M25/025Adding water
    • F02M25/03Adding water into the cylinder or the pre-combustion chamber
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

Description

  The present invention relates to an internal combustion engine.

  In the case of an internal combustion engine that directly injects fuel into the combustion chamber, the fuel injected from the fuel injection valve burns when it comes into contact with air that has become hot due to compression. When the load of the internal combustion engine is large, the injected fuel mainly burns by diffusion combustion. However, the temperature of the combustion gas generated by the combustion of the fuel increases with the passage of time from the fuel injection. Therefore, the injected fuel is ignited without sufficient mixing time with air (see Patent Document 1). As a result, the injected fuel and air are not sufficiently mixed, causing PM (Particulate Matter) such as smoke to be generated.

Japanese Patent No. 2864896

  Accordingly, an object of the present invention is to reduce the generation of PM by lowering the temperature of the air-fuel mixture in which the fuel injected from the fuel injection valve and air are mixed and sufficiently ensuring the ignition delay of the injected fuel. It is to provide an internal combustion engine.

  According to the first aspect of the present invention, the liquid injection valve is provided independently of the fuel injection valve. The liquid injection valve injects non-combustible liquid toward the fuel spray formed in the combustion chamber by the fuel injected from the fuel injection valve. By injecting the non-combustible liquid toward the fuel spray, the fuel spray is cooled by the injected non-combustible liquid. Therefore, an increase in the temperature of the combustion gas caused by the combustion of fuel can be suppressed. As a result, the temperature of the air-fuel mixture in which the fuel and air injected from the fuel injection valve are mixed decreases. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the invention according to claim 2, the liquid injection valve injects the non-combustible liquid toward the spray mixing region. The fuel is sprayed from the fuel injection valve into the combustion chamber. At this time, the spray formed by the fuel injected from the fuel injection valve includes a liquid region, a mixing region, and a combustion region. The liquid region is a region where the fuel injected from the fuel injection valve is in the form of droplets. The mixing region is formed at a position farther from the fuel injection valve than the liquid region, that is, at the spraying tip side of the liquid region. In the mixing region, the vaporized fuel is mixed with air but not ignited. The combustion region is formed further away from the fuel injection valve than the mixing region, that is, at the tip of the spray. In the combustion region, fuel mixed with air is ignited to generate a flame. In the invention according to claim 2, the liquid injection valve injects the non-combustible liquid into the mixing region among the fuel sprays divided into these three regions. This lowers the temperature of the air-fuel mixture in the mixing region and reduces the propagation of flame from the combustion region to the mixing region. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the invention according to claim 3, the liquid injection valve injects the non-combustible liquid from the rear with respect to the injection direction of the fuel spray injected from the fuel injection valve. The fuel injected from the fuel injection valve forms a fuel spray that travels away from the fuel injection valve. Therefore, the liquid injection valve injects the non-combustible liquid so as to follow the fuel spray from the rear toward the fuel injection direction in the traveling direction of the fuel spray. Thereby, formation of the fuel spray injected from the fuel injection valve is not hindered by the non-combustible liquid injected from the liquid injection valve. Therefore, the fuel spray can be stably formed.

  In the invention according to claim 4, the liquid injection valve injects the non-combustible liquid from the front with respect to the injection direction of the fuel spray injected from the fuel injection valve. The fuel injected from the fuel injection valve forms a fuel spray that travels away from the fuel injection valve. Therefore, the liquid injection valve injects the non-combustible liquid so as to collide with the fuel spray from the front while facing the fuel injection direction from the front in the traveling direction of the fuel spray. Thereby, it is not necessary to arrange | position the fuel injection valve and the liquid injection valve close. Therefore, the fuel injection valve and the liquid injection valve can be easily arranged in the vicinity of the combustion chamber where the space is limited. Further, by injecting the non-combustible liquid from the front of the fuel spray, the non-combustible liquid can be easily injected toward the mixing region of the fuel spray.

According to the first aspect of the present invention, the control means starts the injection of the non-combustible liquid from the liquid injection valve after the fuel injected from the fuel injection valve is ignited. In order to ensure a sufficient ignition delay, the expansion of the flame from the combustion region to the mixing region may be reduced. Therefore, by injecting the non-combustible liquid after the injected fuel is ignited, the generation of the flame, that is, the expansion of the generated flame region while reducing the ignitability is reduced. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

According to the first aspect of the present invention, the control means increases the injection rate of the non-combustible liquid as the amount of fuel injected increases. Here, the control means increases the injection rate of the non-combustible liquid, that is, the injection amount per unit time. When the amount of injected fuel increases, the combustion temperature rises and the combustion region expands to the fuel injection valve side. Therefore, by increasing the injection rate of the non-combustible liquid, a large amount of non-combustible liquid is injected toward the fuel spray in a short time. Therefore, it is possible to sufficiently ensure the ignition delay of the injected fuel during the fuel injection period, and to reduce the generation of PM.

In the invention according to claim 5 , the non-combustible liquid contains water as a main component. Therefore, non-combustible liquid can be made inexpensive. Moreover, water has a large heat capacity and heat of vaporization. Therefore, the water injected toward the fuel spray is vaporized into water vapor, thereby lowering the temperature inside the combustion chamber. Therefore, the combustion temperature of the fuel can be reduced, and the production of NOx can be reduced. Further, the injected water is mixed with the fuel spray while being vaporized. Therefore, the water vapor generated by the vaporization of water is mixed with the fuel spray while entraining the surrounding air. As a result, water vapor that entrains air and mixes it with the fuel spray supplies oxygen in the air to the fuel spray. Therefore, complete combustion of the fuel can be promoted, and the production of PM can be further reduced.

The schematic diagram which shows the structure of the internal combustion engine by 1st Embodiment. Sectional drawing which shows the outline of the vicinity of the combustion chamber of the internal combustion engine by 1st Embodiment In the internal combustion engine by 1st Embodiment, it is a schematic diagram which shows arrangement | positioning of a fuel injection valve and a liquid injection valve, spray of a fuel, and spray of water, (A) is a figure equivalent to FIG. 2, (B) is a combustion chamber. Viewed from the cylinder head side The schematic diagram which shows the spray of the fuel injected from a fuel injection valve, and the spray of the water injected from a liquid injection valve in the internal combustion engine by 1st Embodiment. Schematic showing the flow of operation of the internal combustion engine according to the first embodiment In the internal combustion engine by 1st Embodiment, the schematic which shows the injection timing of a fuel injection valve and a liquid injection valve, and injection pressure The figure equivalent to FIG. 3 of the internal combustion engine by 2nd Embodiment.

Hereinafter, a plurality of embodiments of an internal combustion engine will be described based on the drawings. Note that, in a plurality of embodiments, substantially the same components are denoted by the same reference numerals, and description thereof is omitted.
(First embodiment)
1 and 2 show an internal combustion engine according to a first embodiment. In the case of the first embodiment, the internal combustion engine is a diesel engine (hereinafter referred to as “engine”) 10. The engine 10 includes an internal combustion engine main body (hereinafter referred to as “engine main body”) 11, a fuel injection valve 12, and a liquid injection valve 13. As shown in FIG. 2, the engine body 11 includes a cylinder block 14, a cylinder head 15, a piston 16, and the like. The cylinder block 14 forms a cylindrical cylinder 17. The piston 16 reciprocates in the axial direction inside the cylinder 17. The inner wall of the cylinder block 14, the end face of the cylinder head 15, and the end face of the piston 16 form a combustion chamber 18. The fuel injection valve 12 is provided through the cylinder head 15. Thereby, the tip of the fuel injection valve 12 is exposed to the combustion chamber 18. Similarly, the liquid injection valve 13 is provided through the cylinder head 15. Thereby, the tip of the liquid injection valve 13 is exposed to the combustion chamber 18.

  In addition to the above, the engine 10 includes an intake system 21, an exhaust system 22, a fuel supply device 23, a liquid supply device 24, an EGR (Exhaust Gas Recirculation) device 25, a supercharging device 26, and control means as shown in FIG. An ECU (Electronic Control Unit) 27 is provided. The intake system 21 includes an intake pipe member 31 and a throttle 32. The intake pipe member 31 forms an intake passage 33. The intake passage 33 formed by the intake pipe member 31 has one end opened to the atmosphere and the other end connected to the combustion chamber 18. As shown in FIG. 2, the intake passage 33 and the combustion chamber 18 are opened and closed by an intake valve 34. The throttle 32 opens and closes the intake passage 33 and controls the flow rate of intake air flowing through the intake passage 33. As shown in FIG. 1, the exhaust system 22 includes an exhaust pipe member 35, an exhaust purification unit 36, and the like. The exhaust pipe member 35 forms an exhaust passage 37. The exhaust passage 37 formed by the exhaust pipe member 35 has one end connected to the combustion chamber 18 and the other end open to the atmosphere. As shown in FIG. 2, the exhaust passage 37 and the combustion chamber 18 are opened and closed by an exhaust valve 38. The exhaust purification unit 36 is provided in the exhaust passage 37 and purifies the exhaust gas flowing through the exhaust passage 37. The exhaust purification unit 36 purifies various emissions such as NOx and PM contained in the exhaust by, for example, adsorption or chemical reaction.

  As shown in FIG. 1, the fuel supply device 23 includes a fuel injection pump 41 and a common rail 42. The fuel injection pump 41 is driven by the engine body 11 and pressurizes fuel stored in a fuel tank (not shown). In the case of a diesel engine as in this embodiment, the fuel is light oil. The fuel is not limited to light oil, and any fuel such as heavy oil, natural gas, biomass fuel, various alcohols, and ethers can be used. The fuel pressurized by the fuel injection pump 41 is supplied to the common rail 42. The common rail 42 stores the fuel pressurized by the fuel injection pump 41 while maintaining the pressure. The fuel injection valve 12 is connected to the common rail 42. The fuel stored in the common rail 42 is injected into the combustion chamber 18 via the fuel injection valve 12.

  The liquid supply device 24 includes a liquid pressurizing pump 43 and a common rail 44. The liquid pressurizing pump 43 is driven by the engine body 11 and pressurizes liquid stored in a liquid tank (not shown). Here, the liquid is a non-combustible liquid that does not burn with fuel. In the present embodiment, the non-combustion liquid is water. The non-combustible liquid is not limited to water, and may be an aqueous solution obtained by adding non-combustible additives such as various ions and organic substances to water. Hereinafter, “water” will be described as an example of the non-combustible liquid. The water pressurized by the liquid pressurizing pump 43 is supplied to the common rail 44. The common rail 44 stores the water pressurized by the liquid pressurizing pump 43 while maintaining the pressure. The liquid injection valve 13 is connected to the common rail 44. The water stored in the common rail 44 is injected into the combustion chamber 18 via the liquid injection valve 13.

  The EGR device 25 includes an EGR pipe portion 46, an EGR valve 47, and a cooler 48. The EGR pipe portion 46 forms an EGR passage 49. The EGR passage 49 has one end connected to the exhaust passage 37 and the other end connected to the intake passage 33. The EGR valve 47 opens and closes an EGR passage 49 formed by the EGR pipe portion 46. Thereby, when the EGR valve 47 opens the EGR passage 49, part of the exhaust gas flowing through the exhaust passage 37 is returned to the intake passage 33. The cooler 48 cools the exhaust gas that is returned from the exhaust passage 37 to the intake passage 33.

  The supercharger 26 has a turbine 51, a compressor 52, and an intercooler 53. The turbine 51 is provided in the exhaust passage 37, and the compressor 52 is provided in the intake passage 33. The turbine 51 and the compressor 52 are connected by a shaft (not shown). The turbine 51 is rotationally driven by the exhaust flowing through the exhaust passage 37. The rotational force of the turbine 51 is transmitted to the compressor 52 via a shaft (not shown) to drive the compressor 52 to rotate. The compressor 52 provided in the intake passage 33 pressurizes the air flowing through the intake passage 33 by rotating. Thereby, the supercharging device 26 supercharges the air supplied to the combustion chamber 18. The intercooler 53 cools the air supplied to the combustion chamber 18 via the intake passage 33.

  The ECU 27 is configured by a microcomputer having a CPU, a ROM, and a RAM (not shown). The ECU 27 controls the entire engine 10 including opening and closing of the fuel injection valve 12 and opening and closing of the liquid injection valve 13. The ECU 27 controls driving of the fuel injection valve 12 and the liquid injection valve 13 according to a computer program stored in the ROM. The ECU 27 corresponds to control means in the claims. Further, the ECU 27 controls driving of the throttle 32 and the EGR valve 47.

  The ECU 27 sets the amount of fuel injected from the fuel injection valve 12 and the fuel injection timing in accordance with a computer program stored in the ROM. Specifically, the ECU 27 acquires the load of the engine 10 from the accelerator opening sensor 55 and the rotation speed sensor 56. Then, the ECU 27 sets the amount of fuel injected from the fuel injection valve 12 and the fuel injection timing based on the acquired load of the engine 10. In addition, the ECU 27 also sets the injection amount of water injected from the liquid injection valve 13 and the injection timing of water based on the set fuel injection amount from the fuel injection valve 12 and the fuel injection timing. Here, the accelerator opening sensor 55 is a sensor that detects the opening of the accelerator pedal, and the rotation speed sensor 56 is a sensor that detects the rotation speed of the engine body 11.

  The ECU 27 is connected to a water temperature sensor, an intake air temperature sensor, etc. (not shown). The ECU 27 corrects the fuel injection amount based on the coolant temperature of the engine body 11 detected by a water temperature sensor (not shown), the intake air temperature detected by the intake air temperature sensor, and the like. The ECU 27 is further connected to a pressure sensor 57 and a pressure sensor 58. The ECU 27 acquires the fuel pressure in the common rail 42 from the pressure sensor 57 and acquires the water pressure in the common rail 44 from the pressure sensor 58. The ECU 27 adjusts the flow rate of the fuel supplied from the fuel injection pump 41 to the common rail 42 based on the fuel pressure acquired from the pressure sensor 57. Similarly, the ECU 27 adjusts the flow rate of water supplied from the liquid pressurizing pump 43 to the common rail 44 based on the water pressure acquired from the pressure sensor 58.

Next, the fuel injection valve 12 and the liquid injection valve 13 configured as described above will be described.
The fuel injection valve 12 has a nozzle hole (not shown) for injecting fuel at the end on the combustion chamber 18 side, and the liquid injection valve 13 has a nozzle hole (not shown) for injecting water at the end on the combustion chamber 18 side. doing. The fuel supplied from the common rail 42 is directly injected from the injection hole of the fuel injection valve 12 toward the combustion chamber 18. Similarly, water supplied from the common rail 44 is injected from the injection hole of the liquid injection valve 13 toward the combustion chamber 18. Each of the fuel injection valve 12 and the liquid injection valve 13 has an electromagnetic valve (not shown). The fuel injection valve 12 and the liquid injection valve 13 intermittently inject fuel or water based on an electrical signal output from the ECU 27 to each electromagnetic valve. The fuel injection valve 12 and the liquid injection valve 13 may drive a needle (not shown) directly by driving an electromagnetic valve to intermittently inject fuel or water, for example, back pressure that presses a needle (not shown) in the valve closing direction. The fuel or water injection may be intermittently interrupted by controlling the valve with a solenoid valve. Further, the fuel injection valve 12 and the liquid injection valve 13 may be driven by a piezoelectric element instead of the electromagnetic valve.

  In the case of the first embodiment, the fuel injection valve 12 is provided at the center in the radial direction of the combustion chamber 18, that is, on the central axes of the piston 16 and the cylinder 17 as shown in FIGS. 1 and 3. The fuel injection valve 12 injects fuel radially. Thus, the fuel forms a plurality of sprays 60 in the circumferential direction from the fuel injection valve 12 toward the radially outer side of the combustion chamber 18. On the other hand, the liquid injection valve 13 is provided at a position adjacent to the fuel injection valve 12. Specifically, the liquid injection valve 13 is provided at a position close to the fuel injection valve 12 on the radially outer side of the combustion chamber 18. Water is jetted radially from the liquid jet valve 13. Thereby, the water of the liquid injection valve 13 is injected so as to follow the fuel spray 60 from behind in the traveling direction of the fuel injected from the fuel injection valve 12.

  The fuel injected from the injection hole of the fuel injection valve 12 forms a spray 60 as shown in FIG. The spray 60 is divided into three regions: a liquid region 61, a mixing region 62, and a combustion region 63. The liquid region 61 is a region that is formed at a position closest to the fuel injection valve 12 and is in the form of a liquid droplet without vaporizing the fuel injected from the injection hole. The mixing region 62 is formed between the liquid region 61 and the combustion region 63, and is a region where the fuel injected from the injection hole is vaporized but not ignited. The combustion region 63 is a region that is formed at a position farthest from the fuel injection valve 12, and the fuel injected from the injection hole is vaporized and ignited. When fuel is injected from the fuel injection valve 12, after the droplet fuel is vaporized, a flame is generated in the combustion region 63 sufficiently mixed with air. The fuel is injected from the fuel injection valve 12 into the combustion chamber 18 at a high pressure. Therefore, the fuel injected from the injection hole reaches the combustion region 63 through the liquid region 61 and the mixing region 62. As a result, the fuel burns in the combustion region 63. Thus, when the fuel injected from the fuel injection valve 12 is stably combusting, the flame region from the combustion region 63 to the mixing region 62 hardly expands.

  On the other hand, when the fuel injection amount is large and the combustion temperature is high, for example, when the engine 10 is in a high load state, the mixture region 62 tends to ignite. This is because, in a high load state, the temperature of the combustion region 63 rises, so that the ignition delay of the air-fuel mixture in front of the combustion region 63 is shortened, so that the flame expands in the mixing region. Thus, when fuel combustion continues as in a high load state, it is difficult to ensure a sufficient ignition delay. If the ignition delay is not sufficiently secured, the flame generated in the combustion region 63 expands to the mixing region 62 or the liquid region 61 as described above. As a result, the mixing of fuel and air becomes insufficient, and this insufficient mixing causes generation of PM.

  In the first embodiment, the liquid injection valve 13 injects water toward the mixing region 62 of the spray 60 formed by the fuel injection valve 12. The water injected from the liquid injection valve 13 forms a spray 70 in the same manner as the fuel. This spraying forms a liquid region 71 in which water is in the form of droplets and a vaporized region 72 in which water is vaporized into water vapor. By injecting fuel from the liquid injection valve 13 toward the mixing region 62 of the fuel spray 60, the water that has become water vapor is mixed with the fuel spray in the mixing region 62 of the fuel spray 60. That is, the water injected from the liquid injection valve 13 is quickly vaporized into water vapor in the high temperature combustion chamber 18. In the water spray 70, the vaporized region 72 that has become water vapor is mixed into the mixing region 62 of the fuel spray 60. Water vapor generated by vaporization of water has a temperature lower than that of fuel spray due to its own heat of vaporization. Therefore, the water vapor mixed with the fuel spray in the mixing region 62 cools the fuel spray in the mixing region 62. As a result, the flame generated in the combustion region 63 is difficult to propagate to the mixing region 62 where the temperature has decreased. As a result, the propagation speed of the flame, that is, the combustion speed of the fuel is decreased, and the fuel spray 60 is sufficiently ensured in the ignition delay. That is, even when the temperature of the combustion chamber 18 is high, the mixing time of the fuel spray 60 and the air can be sufficiently ensured. Further, the water injected from the liquid injection valve 13 is vaporized into water vapor, so that the vaporized water vapor reaches the mixing region 62 of the fuel spray 60 in a state where the surrounding air is entrained. As a result, the fuel spray 60 is mixed with air together with water vapor. Therefore, mixing of fuel with air is further promoted.

Next, the flow of operation of the engine 10 having the above configuration will be described with reference to FIG.
The engine 10 executes a basic control routine during the operation period. The ECU 27 shifts to an injection control routine for fuel and water injection at a time set in advance in this basic control routine. When the ECU 27 proceeds to the injection control routine, the ECU 27 acquires the opening degree of the accelerator pedal and the rotational speed of the engine body 11 (S101). Specifically, the ECU 27 acquires the opening degree of an accelerator pedal (not shown) from the accelerator opening degree sensor 55 and the rotation speed of the engine body 11 from the rotation speed sensor 56. When the ECU 27 acquires the accelerator opening and the rotation speed of the engine body 11, the ECU 27 sets the fuel injection amount, the injection timing, and the injection pressure (S102). The ECU 27 refers to, for example, a map that is set in advance and stored in the ROM, and sets the fuel injection amount, the injection timing, and the injection pressure based on the detected accelerator opening and the number of revolutions of the engine body 11. Further, the ECU 27 sets the water injection amount, the injection timing, and the injection pressure from the acquired accelerator opening degree and the rotational speed of the engine body 11 (S103). In this case as well, the ECU 27 refers to, for example, a map that is set in advance and stored in the ROM, and determines the water injection amount, the injection timing, and the injection pressure based on the detected accelerator opening and the rotational speed of the engine body 11. Set.

  The ECU 27 returns to the basic control routine after setting the fuel and water injection amounts, the injection timing, and the injection pressure in S102 and S103. When it is time to control fuel injection in the basic control routine, the ECU 27 drives the fuel injection valve 12 based on the fuel injection amount and injection timing set in S102. Similarly, when it is time to control water injection in the basic control routine, the ECU 27 drives the liquid injection valve 13 based on the water injection amount and injection time set in S103. Further, the ECU 27 controls the fuel injection pump 41 based on the fuel injection pressure set in S102 when it is time to control the amount of fuel supplied to the common rail 42 in the basic control routine. Similarly, when it is time to control the amount of water supplied to the common rail 44 in the basic control routine, the ECU 27 controls the liquid pressurizing pump 43 based on the water injection pressure set in S103.

  In S102 and S103, the ECU 27 sets the fuel and water injection timing as shown in FIG. The ECU 27 injects fuel prior to water injection. That is, the ECU 27 first drives the fuel injection valve 12 to start fuel injection, and then drives the liquid injection valve 13 to inject water after a predetermined period has elapsed. This is because the water injected from the liquid injection valve 13 is injected into the mixing region 62 of the fuel spray 60 of the fuel injection valve 12. That is, after the fuel injected from the fuel injection valve 12 forms a spray 60 as shown in FIG. 4, the liquid injection valve 13 injects water toward the mixing region 62 of the spray 60. Therefore, the time difference from the start of fuel injection by the fuel injection valve 12 to the start of water injection by the liquid injection valve 13 corresponds to the time difference until the fuel spray 60 is formed. The time difference from the start of fuel injection to the start of water injection is determined by the load of the engine 10. That is, the time difference from the start of fuel injection to the start of water injection becomes shorter as the fuel injection amount increases and the combustion temperature of the fuel tends to increase. The ECU 27 continues to inject water from the liquid injection valve 13 for a predetermined time even after the fuel injection from the fuel injection valve 12 is completed. This is because the fuel combustion in the combustion chamber 18 continues even after the fuel injection is completed. That is, the ECU 27 continues to inject water from the liquid injection valve 13 while fuel combustion continues in the combustion chamber 18.

  Further, as shown in FIG. 6, the ECU 27 sets the injection pressure of water injected from the liquid injection valve 13 to be higher than the injection pressure of fuel injected from the fuel injection valve 12. This is because it is necessary to apply a pressure higher than that of the fuel spray 60 in order to mix water vapor generated from water with the fuel injected from the fuel injection valve 12. By making the water pressure higher than the fuel pressure, the water injected from the liquid injection valve 13 is easily mixed into the fuel spray 60. In the case of the first embodiment, as shown in FIG. 3, the liquid injection valve 13 injects water from the rear side in the traveling direction of the spray 60 formed by the fuel injection valve 12. Therefore, by increasing the pressure of the water jetted from the liquid jet valve 13, the water jetted from the liquid jet valve 13 has a higher traveling speed. As a result, even when water is injected from behind the fuel spray 60, the water easily catches up with the fuel spray 60 and is mixed with the fuel spray 60.

  Further, the ECU 27 sets the injection rate of water injected from the liquid injection valve 13, that is, the injection amount per unit time, to be larger than the injection rate of the fuel injected from the fuel injection valve 12. In particular, as the load state of the engine 10 increases, the ECU 27 increases the injection rate of water injected from the liquid injection valve 13. As the load state of the engine 10 increases, the amount of fuel injected from the fuel injection valve 12 increases. Therefore, the combustion temperature of the fuel in the combustion chamber 18 rises, and the flame propagation speed also increases. Therefore, the ECU 27 injects a large amount of water toward the fuel spray 60 in a short time by increasing the water injection rate.

  In the first embodiment described above, the engine 10 includes the liquid injection valve 13 provided independently of the fuel injection valve 12. The liquid injection valve 13 injects water toward the fuel spray 60 formed in the combustion chamber 18 by the fuel injected from the fuel injection valve 12. By injecting water toward the fuel spray 60, the fuel spray 60 is cooled by the injected water. Therefore, an increase in the temperature of the combustion gas caused by the combustion of fuel can be suppressed. As a result, the temperature of the air-fuel mixture in which the fuel injected from the fuel injection valve 12 and air are mixed decreases, and the expansion of the flame region to the mixing region 62 is prevented. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the first embodiment, the liquid injection valve 13 injects water toward the mixing region 62 of the spray 60. This lowers the temperature of the air-fuel mixture in the mixing region 62 and reduces the expansion of the flame region from the combustion region 63 to the mixing region 62. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the first embodiment, the liquid injection valve 13 injects water from the rear in the traveling direction of the spray 60 with respect to the injection direction of the fuel spray 60 injected from the fuel injection valve 12. That is, the liquid injection valve 13 injects water so as to follow the spray 60 along the fuel injection direction from the rear in the traveling direction of the fuel spray 60. Accordingly, the fuel spray 60 injected from the fuel injection valve 12 is not prevented from advancing by the water injected from the liquid injection valve 13. Therefore, the penetration force of the spray 60 can be maintained, and the fuel spray 60 can be stably formed.

  In the first embodiment, the ECU 27 starts water injection from the liquid injection valve 13 after the fuel injected from the fuel injection valve 12 ignites. In order to ensure a sufficient ignition delay, the propagation of flame from the combustion region 63 to the mixing region 62 may be reduced. Therefore, by injecting water after the injected fuel is ignited, propagation of the generated flame is reduced while ensuring the generation of flame, that is, the ignitability. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the first embodiment, the ECU 27 increases the water injection rate as the amount of injected fuel increases. Here, the ECU 27 increases the injection rate of water, that is, the injection amount per unit time. When the amount of fuel injected increases, the combustion temperature rises and the flame area expands. Therefore, by increasing the water injection rate, a large amount of water is injected toward the fuel spray 60 in a short time. Therefore, a sufficient ignition delay of the injected fuel can be ensured, and the generation of PM can be reduced.

  In the first embodiment, water is the main component as the non-combustible liquid. Therefore, non-combustible liquid is inexpensive. Moreover, water has a large heat capacity and heat of vaporization. Therefore, the water injected toward the fuel spray 60 is vaporized into water vapor, thereby lowering the temperature inside the combustion chamber 18. Therefore, the combustion temperature of the fuel can be reduced, and the production of NOx can be reduced. Further, the injected water is mixed with the fuel spray 60 while being vaporized. Therefore, the water vapor generated by the vaporization of water is mixed with the fuel spray 60 while entraining the surrounding air. As a result, the air spray 70 supplies oxygen in the air to the fuel spray 60. Therefore, complete combustion of the fuel can be promoted, and the production of PM can be further reduced.

(Second Embodiment)
An engine according to the second embodiment will be described.
FIG. 7 is a view schematically showing the arrangement of the fuel injection valve 12 and the liquid injection valve 13 in the engine 10 according to the second embodiment. In the case of the second embodiment, the fuel injection valve 12 and the liquid injection valve 13 are disposed on opposite end portions in the radial direction of the combustion chamber 18. That is, the fuel injection valve 12 and the liquid injection valve 13 are arranged at symmetrical positions with the center in the radial direction of the combustion chamber 18. In this case, the fuel injection valve 12 arranged on one end side in the radial direction of the combustion chamber 18 injects fuel to the liquid injection valve 13 side arranged on the other end side in the radial direction. On the other hand, the liquid injection valve 13 arranged on the other end side in the radial direction of the combustion chamber 18 injects water to the fuel injection valve 12 side. Thereby, the water of the liquid injection valve 13 is injected so as to strike the fuel spray 60 from the front in the traveling direction of the fuel injected from the fuel injection valve 12. That is, the water spray 70 collides from the front in the traveling direction of the fuel spray 60. Also in the case of the second embodiment, water is injected toward the mixing region 62 of the fuel spray 60 injected from the fuel injection valve 12 as in the first embodiment.

  In the second embodiment, the liquid injection valve 13 injects water from the front with respect to the injection direction of the fuel spray 60 injected from the fuel injection valve 12. That is, the liquid injection valve 13 injects water so as to collide with the fuel spray 60 from the front in the direction of travel of the fuel spray 60 injected from the fuel injection valve 12, opposite the fuel injection direction from the front. Thereby, it is not necessary to arrange | position the fuel injection valve 12 and the liquid injection valve 13 closely. Therefore, the fuel injection valve 12 and the liquid injection valve 13 can be easily arranged in the vicinity of the combustion chamber 18 where the space is limited. Also, by injecting water from the front of the fuel spray 60, the water injection position can be easily determined, and water can be easily injected toward the mixing region 62 of the fuel spray 60.

(Other embodiments)
The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

  For example, in the above embodiments, a diesel engine has been described as an example of the internal combustion engine. However, the internal combustion engine is not limited to a diesel engine, and may be a direct injection gasoline engine or the like.

  In the drawings, 10 is an engine (internal combustion engine), 11 is an engine body (internal combustion engine body), 12 is a fuel injection valve, 13 is a liquid injection valve, 18 is a combustion chamber, and 27 is an ECU (control means).

Claims (5)

  1. An internal combustion engine body forming a combustion chamber;
    A fuel injection valve for injecting fuel into the combustion chamber;
    A liquid injection valve that is provided independently of the fuel injection valve, and injects non-combustible liquid toward the fuel spray formed in the combustion chamber by the fuel injected from the fuel injection valve to the combustion chamber;
    Control means for controlling the fuel injection timing from the fuel injection valve and the non-combustible liquid injection timing from the liquid injection valve,
    The control means starts injection of the non-combustible liquid from the liquid injection valve after the fuel injected from the fuel injection valve ignites, and increases the amount of fuel injected from the fuel injection valve. And increasing the injection rate of the non-combustible liquid injected from the liquid injection valve .
  2.   The liquid injection valve is formed in the combustion chamber and the fuel injected from the fuel injection valve is a liquid region of liquid, and the fuel is vaporized at a position farther from the fuel injection valve than the liquid region, and is not ignited. 2. The internal combustion engine according to claim 1, wherein the non-combustible liquid is injected toward the mixing region among sprays including a combustion region where fuel is ignited at a position farther from the fuel injection valve than the region and the mixing region. organ.
  3.   The said liquid injection valve injects the said non-combustible liquid toward the fuel injection direction from the back near the said fuel injection valve of the fuel spray with respect to the injection direction of the fuel injected from the said fuel injection valve. The internal combustion engine according to 1 or 2.
  4.   The liquid injection valve injects the non-combustible liquid from the front of the fuel injection valve far from the fuel injection valve in the direction of fuel injection from the fuel injection valve. Item 3. The internal combustion engine according to Item 1 or 2.
  5. The internal combustion engine according to any one of claims 1 to 4, wherein the non-combustible liquid contains water as a main component.
JP2011092061A 2011-04-18 2011-04-18 Internal combustion engine Active JP5532008B2 (en)

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DE201210206307 DE102012206307A1 (en) 2011-04-18 2012-04-17 Internal combustion engine assembly has internal combustion engine in which combustion chamber is formed, where fuel injector is provided with fuel jet that is provided to spray fuel in combustion chamber

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DE102015208489A1 (en) 2015-05-07 2016-11-10 Robert Bosch Gmbh Water injection device of an internal combustion engine and method for operating such a water injection device
DE102017113519A1 (en) 2016-07-19 2017-08-03 FEV Europe GmbH Reciprocating engine and method of operating such
DE102018101773B4 (en) * 2018-01-26 2019-11-14 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Method and device for water injection
FR3087499A1 (en) * 2018-10-22 2020-04-24 Psa Automobiles Sa Device for injecting water into the air intake of internal combustion engines and engine architecture comprising said device

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JP3337307B2 (en) * 1994-02-21 2002-10-21 三菱重工業株式会社 Water injection diesel engine
JP3791100B2 (en) * 1997-03-14 2006-06-28 三菱ふそうトラック・バス株式会社 Water injection amount control device
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