JP5817460B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device for an internal combustion engine.

  In an internal combustion engine, a mixture of fuel and air is supplied to a combustion chamber, and the fuel burns in the combustion chamber. In the prior art, an internal combustion engine having a fuel injection valve capable of injecting high-pressure fuel into a combustion chamber is known.

  Japanese Patent Laid-Open No. 2006-118470 discloses an injector that injects high-pressure gaseous fuel into an engine combustion chamber from an injection hole provided at the tip of a nozzle. The injector includes a control chamber that applies pressure to a needle that opens and closes a nozzle hole, a working liquid supply passage that supplies liquid fuel that serves as working liquid to the control chamber, and an electric that controls the flow of liquid fuel into and out of the control chamber. It is disclosed to include a type switching valve and a high-pressure gaseous fuel supply passage for supplying high-pressure gaseous fuel to the nozzle hole.

  Japanese Patent Laid-Open No. 10-030486 discloses a pressure accumulator that stores fuel from a fuel pressurizing pump, a feed hole that communicates the accumulator and a fuel injection valve, and a control oil that extends from the feed hole to an oil chamber. And a three-way solenoid valve that is provided in the control oil passage and closes the needle valve by applying fuel oil pressure to the oil chamber and opening the needle valve by discharging the fuel oil in the oil chamber. A fuel injection control device is disclosed. This device includes a fuel oil pressure correcting means for correcting the fuel oil pressure based on the temperature of the fuel oil, and a fuel injection amount correcting means for correcting the fuel injection amount at the same time as the fuel oil pressure correcting means. It is disclosed to suppress the temperature and prevent deterioration and damage of members used in the fuel return system.

JP 2006-118470 A Japanese Patent Laid-Open No. 10-030486

  As disclosed in the above patent document, the fuel injection valve can inject fuel by operating the needle valve using the pressure of the working liquid. In particular, even when the pressure of the fuel is high, the fuel can be injected into the combustion chamber or the like by operating the fuel injection valve using the pressure of the working liquid. In such a hydraulically operated fuel injection valve, the needle valve is pressed by the hydraulic pressure to close the injection hole. When fuel is injected, the nozzle hole is opened by lowering the hydraulic pressure of the working liquid pressing the needle valve. The fuel injection amount is controlled by a change in the pressure of the working liquid. However, if the hydraulic pressure of the working liquid that presses the needle valve fluctuates, the actual fuel injection amount may deviate from the desired amount.

  An object of the present invention is to provide a fuel injection device for an internal combustion engine in which the accuracy of the fuel injection amount is improved.

  A fuel injection device for an internal combustion engine according to the present invention includes a fuel injection valve whose opening and closing is controlled by a working liquid, a fuel supply device that supplies pressurized fuel to the fuel injection valve, and a working liquid pressurized to the fuel injection valve. A working liquid supply device for supplying. The working liquid supply device is configured to supply a working liquid different from the fuel. The fuel injection valve is formed so as to open and close the pressure control chamber for storing the working liquid, the control valve for opening and closing the pressure control chamber, the control valve driving device for driving opening and closing of the control valve, and the injection hole for injecting fuel. And an opening / closing member that closes the nozzle hole when pressed by the pressure inside the pressure control chamber. The fuel injection valve is formed such that when the control valve driving device is energized, the control valve is opened to lower the pressure in the pressure control chamber, and the opening / closing member moves to inject fuel. The pressure of the fuel supplied to the fuel injection valve and the pressure of the working liquid are detected, and the energization time of the control valve drive device is adjusted based on the pressure of the fuel and the pressure of the working liquid.

  In the said invention, it is preferable to set the energization time of a control valve drive device so long that the pressure of a working liquid becomes high.

  In the said invention, it is preferable to detect the temperature of the working liquid supplied to a fuel injection valve, and to set the energization time of a control valve drive device short, so that the temperature of a working liquid becomes high.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel-injection apparatus of the internal combustion engine which improves the precision of the fuel injection quantity can be provided.

1 is a schematic view of an internal combustion engine in an embodiment. It is the schematic of the fuel-injection apparatus of the internal combustion engine in embodiment. It is a time chart when fuel is injected from the fuel injection valve in the embodiment. It is a time chart of the pressure in a pressure control chamber when driving a control valve and reducing pressure. It is a flowchart of control of the fuel-injection apparatus in embodiment. It is a map of the reference energization time which makes the fuel injection amount and fuel pressure which are requested | required in embodiment function. It is a map of the correction | amendment term of the energization time regarding the working liquid pressure which makes the fuel injection quantity and the working liquid pressure which are requested | required in embodiment function.

  A fuel injection device for an internal combustion engine according to an embodiment will be described with reference to FIGS. In the present embodiment, an internal combustion engine that uses hydrogen as a gaseous fuel as a fuel will be described as an example.

  FIG. 1 shows a schematic diagram of an internal combustion engine in the present embodiment. The internal combustion engine includes an engine body 1. The engine body 1 includes a combustion chamber 2 for each cylinder and a fuel injection valve 3 for injecting fuel into each combustion chamber 2. A spark plug 7 is disposed in each cylinder. The internal combustion engine in the present embodiment is a spark ignition type.

The engine body 1 includes an intake manifold 4 and an exhaust manifold 5. The intake manifold 4 is connected to an intake air amount detector 8 via an intake duct 6. The intake air amount detector 8 is connected to an air cleaner 9. A throttle valve 10 driven by a step motor is disposed in the intake duct 6. On the other hand, the exhaust manifold 5 is connected to an exhaust purification catalyst 55 as an exhaust treatment device via an exhaust pipe 51. As the exhaust treatment device, any device for purifying exhaust gas can be employed. For example, a three-way catalyst, an oxidation catalyst, or a catalyst that reduces NO _X can be employed. In the exhaust pipe 51 downstream of the exhaust purification catalyst 55 of the present embodiment, the air-fuel ratio (A / F) of the exhaust gas, which is the ratio of hydrocarbon (unburned fuel) and air contained in the exhaust gas, is detected. An air-fuel ratio sensor 56 is provided for this purpose.

  An EGR passage 52 is disposed between the exhaust manifold 5 and the intake manifold 4 to perform exhaust gas recirculation (EGR). An electronically controlled EGR control valve 53 is disposed in the middle of the EGR passage 52. Further, an EGR cooling device 54 for cooling the EGR gas flowing in the EGR passage 52 is disposed in the middle of the EGR passage 52.

  The fuel injection device for an internal combustion engine in the present embodiment includes a fuel injection valve 3 and a fuel supply device that supplies pressurized fuel to the fuel injection valve 3. The fuel supply device in the present embodiment includes a fuel tank 61 and a pressure adjustment valve 62. Each fuel injection valve 3 is connected to a fuel tank 61 via a fuel supply pipe 63.

  In the fuel supply device according to the present embodiment, gaseous fuel is pressurized and stored in the fuel tank 61. The fuel stored in the fuel tank 61 is depressurized by the pressure adjusting valve 62 and supplied to each fuel injection valve 3. A pressure sensor 64 that detects the pressure of the fuel supplied to the fuel injection valve 3 is disposed in the flow path for supplying fuel from the fuel tank 61 to the fuel injection valve 3. In the present embodiment, a pressure sensor 64 is disposed in the fuel supply pipe 63.

  The fuel injection valve 3 in the present embodiment is a direct injection type that supplies fuel directly to the combustion chamber 2. The fuel injection valve 3 is formed to open and close the fuel injection valve 3 by the pressure of the working liquid as will be described later. The fuel injection device in the present embodiment includes a working liquid supply device that supplies a pressurized working liquid to the fuel injection valve 3. The working liquid is supplied to the working liquid supply pipe 73 by the working liquid pump 72. Although the working liquid pump in this Embodiment is an electric pump, it is not restricted to this form, Arbitrary pumps are employable.

  The pressurized working liquid is supplied to each fuel injection valve 3 from the working liquid supply pipe 73. A pressure sensor 74 for detecting the pressure of the working liquid supplied to the fuel injection valve 3 is disposed in the flow path for supplying the working liquid. In the present embodiment, a pressure sensor 74 is disposed in the working liquid supply pipe 73. A temperature sensor 75 for detecting the temperature of the working liquid supplied to the fuel injection valve 3 is disposed in the flow path for supplying the working liquid. In the present embodiment, a temperature sensor 75 is disposed in the working liquid pump 72.

  The internal combustion engine in the present embodiment includes an electronic control unit 30. The electronic control unit 30 in the present embodiment is configured by a digital computer. The electronic control unit 30 includes a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35, and an output port 36 connected to each other by a bidirectional bus 31. In the ROM 32, information such as a map necessary for performing control is stored in advance. The CPU 34 can perform arbitrary calculations and determinations. The RAM 33 is a readable / writable storage device.

  The output signal of the intake air amount detector 8 is input to the input port 35 via the corresponding AD converter 37. Further, output signals of sensors such as the temperature sensor 75, the pressure sensors 64 and 74, and the air-fuel ratio sensor 56 are input to the input port 35 via the corresponding AD converter 37.

  A load sensor 41 that generates an output voltage proportional to the amount of depression of the accelerator pedal 40 is connected to the accelerator pedal 40. The required load can be detected from the output of the load sensor 41. The output signal of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. Further, the input port 35 is connected to a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 15 °. The engine speed and crank angle can be detected from the output of the crank angle sensor 42.

  On the other hand, the output port 36 is connected to the spark plug 7, the step motor for driving the throttle valve 10, and the EGR control valve 53 via a corresponding drive circuit 38. The output port 36 is connected to the pressure regulating valve 62 and the working liquid pump 72 via a corresponding drive circuit 38.

  Thus, the internal combustion engine in the present embodiment directly injects high-pressure gaseous fuel into the combustion chamber, and further ignites with the spark plug. With this configuration, for example, it is possible to improve fuel combustibility and reduce fuel consumption as compared with a port injection type internal combustion engine that injects fuel into an intake port. Also, by performing diffusion combustion inside the combustion chamber, abnormal combustion such as knocking can be avoided.

  FIG. 2 is a schematic view of the fuel injection device in the present embodiment. The working liquid supply apparatus in the present embodiment includes a working liquid tank 71 that stores working liquid 70. As the working liquid 70, any liquid for driving the fuel injection valve 3 can be used. For example, lubricating oil such as silicon oil or light oil can be used. When the working liquid pump 72 is driven, the working liquid 70 is supplied from the working liquid tank 71 to the fuel injection valve 3 as indicated by an arrow 101. The working liquid 70 is pressurized to a predetermined pressure by the working liquid pump 72. The working liquid 70 that has passed through the inside of the fuel injection valve 3 is returned to the working liquid tank 71 through the working liquid return pipe 76 as indicated by an arrow 102.

  The fuel injection valve 3 in the present embodiment is a liquid-actuated high-pressure gas fuel injection valve that operates with a working liquid. The fuel injection valve 3 includes a cylindrical nozzle body 12 having an injection hole 11 for injecting fuel at the tip. The fuel injection valve 3 includes a needle valve 13 as an opening / closing member for opening / closing the injection hole 11. The needle valve 13 has a main piston 13a and a sub piston 13b connected to the main piston 13a. In the present embodiment, the nozzle hole 11 is opened and closed by the sub-piston 13b. The needle valve 13 is arranged coaxially with the nozzle body 12 and is formed so as to be able to reciprocate inside the nozzle body 12. The nozzle hole 11 opens and closes according to the reciprocating motion of the needle valve 13. An intermediate chamber 14 is formed between the main piston 13a and the sub piston 13b. A spring 15 as an urging member is disposed in the intermediate chamber 14. The spring 15 urges the needle valve 13 in the valve closing direction.

  A pressure control chamber 16 is formed in the nozzle body 12 by the end face of the main piston 13 a and the inner surface of the nozzle body 12. Inside the nozzle body 12, a nozzle chamber 17 is formed by the outer peripheral surface of the sub-piston 13 b and the inner surface of the nozzle body 12.

  Further, the fuel injection valve 3 includes a working liquid supply path 18 that guides the working liquid supplied from the working liquid supply device into the pressure control chamber 16. The fuel injection valve 3 includes a communication path 20 and a working liquid discharge path 21 for discharging the working liquid in the pressure control chamber 16 to the working liquid return pipe 76. By discharging the working liquid in the pressure control chamber 16 to the working liquid tank 71, the internal pressure of the pressure control chamber 16 can be reduced.

  An inlet-side orifice 22 that adjusts the amount of working liquid flowing into the pressure control chamber 16 is disposed in the working liquid supply path 18. In addition, an outlet-side orifice 23 for adjusting the outflow amount of the working liquid is disposed in the discharge path from the pressure control chamber 16. The outlet side orifice 23 is formed to have a larger flow rate than the inlet side orifice 22. The fuel injection valve 3 is configured such that the flow rate of the working liquid flowing out from the pressure control chamber 16 is larger than the flow rate of the working liquid flowing into the pressure control chamber 16 when the control valve 25 is opened. .

  The nozzle body 12 of the fuel injection valve 3 has a fuel supply path 19 that guides the fuel supplied from the fuel supply device to the nozzle chamber 17. The fuel supply path 19 is connected to a fuel supply pipe 63 of the fuel supply device.

  The fuel injection valve 3 in the present embodiment includes a pressure control chamber 16 that stores the working liquid, a control valve 25 that opens and closes the pressure control chamber 16, and a control valve driving device that drives opening and closing of the control valve 25. The control valve driving device in the present embodiment includes a solenoid actuator 24 for opening and closing the control valve 25. By energizing the solenoid actuator 24, the control valve 25 can be opened. Thus, the pressure control chamber 16 in the present embodiment is opened and closed by the electromagnetic valve. The control valve 25 is urged in the valve closing direction by a spring 26. The solenoid actuator 24 is connected to the output port 36 of the electronic control unit 30 via a corresponding drive circuit 38 (see FIG. 1). The solenoid actuator 24 is controlled by the electronic control unit 30.

  When the control valve 25 is closed, the high-pressure working liquid supplied from the working liquid supply device is sealed in the pressure control chamber 16 to maintain the internal pressure of the pressure control chamber 16 at a high pressure. When the control valve 25 is opened, the working liquid is discharged from the pressure control chamber 16 to the working liquid discharge passage 21 to reduce the internal pressure of the pressure control chamber 16.

  In the fuel injection valve 3 in the present embodiment, when the needle valve 13 is to be closed, the control valve 25 is closed by stopping energization of the solenoid actuator 24. When the control valve 25 is closed, the internal pressure in the pressure control chamber 16 is increased by the inflow of the working liquid, and the main piston 13a is urged in the valve closing direction by the internal pressure. The needle valve 13 is urged in the valve closing direction by a spring 15. On the other hand, since pressurized fuel is supplied to the nozzle chamber 17 through the fuel supply path 19, the sub piston 13 b is urged in the valve opening direction by the internal pressure of the nozzle chamber 17. Further, since the injection hole 11 faces the combustion chamber 2, the tip of the needle valve 13 is pressed by the pressure in the combustion chamber 2, and the needle valve 13 is urged in the valve opening direction. When the needle valve 13 is to be closed, the internal pressure of the pressure control chamber 16 is set so that the force acting on the needle valve 13 in the valve closing direction is greater than the force acting on the valve opening direction.

  When the needle valve 13 is to be opened, the control valve 25 is opened by energizing the solenoid actuator 24. When the control valve 25 is opened, the working liquid in the pressure control chamber 16 is discharged from the working liquid discharge path 21. At this time, since the outlet-side orifice 23 is larger than the inlet-side orifice 22, the amount of working fluid flowing out from the pressure control chamber 16 is larger than the amount of working fluid flowing into the pressure control chamber 16. The internal pressure of the pressure control chamber 16 decreases. The force applied to the needle valve 13 in the valve closing direction is reduced, and the needle valve 13 moves and opens as shown by the arrow 103, and fuel is injected from the injection hole 11.

  Thereafter, when the energization of the solenoid actuator 24 is stopped and the control valve 25 is closed again, the internal pressure in the pressure control chamber 16 is accumulated and increased, and the urging force of the needle valve 13 in the valve closing direction is opened. When it becomes larger than the urging force in the direction, the needle valve 13 is closed. Thus, by controlling the opening and closing of the control valve 25, the opening and closing of the needle valve 13, that is, the fuel injection can be controlled.

  The fuel injection device according to the present embodiment uses a liquid different from the fuel injected into the combustion chamber as a working liquid for controlling the fuel injection valve. When the fuel supplied to the combustion chamber is a gas, if the fuel is used as the working fluid of the fuel injection valve, the injection control of the fuel injection valve becomes difficult because the gas has compressibility. When the working fluid to be sealed in the pressure control chamber is made into a gas, the gas has compressibility, so that, for example, the internal pressure of the pressure control chamber vibrates and it becomes difficult to control the opening and closing of the needle valve. Further, when reducing the internal pressure of the pressure control chamber, it is necessary to return the working fluid stored in the pressure control chamber to the tank. However, when the working fluid is a gas, the inside of the tank has a high pressure, and there is a problem that it cannot be returned to the tank unless a pump or the like is arranged to pressurize the working fluid.

  When the fuel supplied to the combustion chamber is a gas as in the present embodiment, the internal pressure of the pressure control chamber is accurately adjusted by using a liquid having a low compressibility as the working fluid for controlling the fuel injection valve. be able to. When the fuel is liquid, the working liquid for controlling the fuel injection valve may be the same as the fuel.

  FIG. 3 shows a time chart when fuel is injected from the fuel injection valve. Until the crank angle θ1, the control signal for opening the control valve 25 is not transmitted, and the solenoid actuator 24 is not energized. The control valve 25 is maintained in a closed state. The inside of the pressure control chamber 16 is maintained at a predetermined pressure. At the crank angle θ1, a control signal for opening the control valve 25 is transmitted. Energization of the solenoid actuator 24 is started, and the control valve 25 is opened.

  When the control valve 25 is in an open state, the working liquid stored in the pressure control chamber 16 flows out, and the pressure in the pressure control chamber 16 starts to decrease. At the subsequent crank angle θ2, the pressure in the pressure control chamber 16 decreases to the valve opening pressure at which the needle valve 13 starts to move. The needle valve 13 starts moving, and the amount of movement of the needle valve 13 becomes greater than zero. As the moving amount of the needle valve 13 increases, fuel is injected from the nozzle hole 11. The amount of movement of the needle valve 13 is increased to a predetermined amount, and the fuel injection amount per unit time is increased to a predetermined amount.

  Thereafter, a control signal for closing the control valve 25 is transmitted at the crank angle θ3, and the energization of the solenoid actuator 24 is stopped. The energization is stopped after a predetermined energization time has elapsed since the start of energization at the crank angle θ1. The control valve 25 returns to the original position before the movement and is in a closed state. The pressure inside the pressure control chamber 16 increases, and the needle valve 13 moves in the valve closing direction. At the crank angle θ <b> 4, the pressure inside the pressure control chamber 16 increases to the valve opening pressure of the control valve 25. The amount of movement of the needle valve 13 becomes zero at the crank angle θ5 with a time delay from the crank angle θ4. The needle valve 13 is seated, and the nozzle hole 11 is closed by the needle valve 13. At the crank angle θ5, the fuel injection amount per unit time is zero.

  In the fuel injection device of the present embodiment, the time during which the control signal for opening the control valve is transmitted corresponds to the energization time from the start of energization of the solenoid actuator 24 to the end of energization. The time during which fuel is injected from the fuel injection valve 3 is determined according to the energization time. That is, the amount of fuel in one fuel injection is determined according to the energization time of the solenoid actuator 24. For example, as the energization time of the solenoid actuator 24 becomes longer, the amount of fuel injected at one time increases.

  In the fuel injection valve 3 of the present embodiment, the time during which the pressure in the pressure control chamber 16 is less than the valve opening pressure corresponds to the time during which fuel is being injected. Incidentally, the pressure inside the pressure control chamber 16 depends on the pressure of the working liquid supplied to the pressure control chamber 16, and the pressure of the working liquid supplied to the pressure control chamber 16 changes depending on the operating condition of the internal combustion engine. There is a case.

  FIG. 4 shows a graph for explaining a change in pressure inside the pressure control chamber when fuel is injected. In FIG. 4, the case where the inside of the pressure control chamber 16 before the control valve 25 opens is the first pressure and the case where the second pressure is lower than the first pressure are illustrated.

  With reference to the example of the first pressure inside the pressure control chamber 16, when the needle valve 13 is opened, the pressure inside the pressure control chamber 16 starts to decrease at the crank angle θ6. At the crank angle θ2a, the pressure inside the pressure control chamber 16 decreases to the valve opening pressure at which the needle valve 13 moves. The needle valve 13 is shifted to an open state. When the needle valve 13 is closed, the pressure inside the pressure control chamber 16 starts to rise at the crank angle θ7. The valve reaches the valve opening pressure at the crank angle θ3a, and the needle valve 13 is closed.

  In the example in which the inside of the pressure control chamber 16 is the second pressure, when the needle valve 13 is opened, the pressure inside the pressure control chamber 16 before the pressure starts to drop is low, so that the valve opening pressure is reached in a short time. descend. That is, when the working liquid having a low pressure is supplied by the working liquid supply device, the pressure of the pressure control chamber 16 when the energization of the solenoid actuator 24 is started is low, so that the opening timing of the needle valve 13 is advanced. .

  In the example shown in FIG. 4, in the case of the second pressure, after the pressure inside the pressure control chamber 16 starts to drop at the crank angle θ6, the pressure in the pressure control chamber 16 changes to the valve opening pressure at the crank angle θ2b. Has reached. The crank angle θ2b reaching the valve opening pressure is ΔθX earlier than the timing of the crank angle θ2a reaching the valve opening pressure at the first pressure. The fuel injection device in the present embodiment has a characteristic that the needle valve 13 opens earlier as the pressure of the working liquid supplied to the pressure control chamber 16 is lower.

  On the other hand, when the pressure of the working liquid in the pressure control chamber 16 is the second pressure when the needle valve 13 is closed, the pressure of the working liquid supplied to the pressure control chamber 16 is low. The increase rate of the pressure inside 16 becomes low. That is, as the pressure of the working liquid supplied to the pressure control chamber 16 decreases, it takes time for the pressure inside the pressure control chamber 16 to increase. For this reason, the time when the pressure inside the pressure control chamber 16 reaches the valve opening pressure is delayed, and the time when the needle valve is closed is delayed. For this reason, the period during which the needle valve 13 is open is longer than in the case of the first pressure.

  In the example shown in FIG. 4, in the case of the second pressure, after the pressure inside the pressure control chamber 16 starts to increase at the crank angle θ7, the pressure inside the pressure control chamber 16 opens at the crank angle θ3b. The valve pressure has increased. The crank angle θ3b reaching the valve opening pressure is delayed by ΔθY from the timing of the crank angle θ3a reaching the valve opening pressure at the time of the first pressure. The fuel injection device in the present embodiment has a characteristic that the needle valve 13 closes later as the pressure of the working liquid supplied to the pressure control chamber 16 is lower.

  Thus, even when the energization time of the solenoid actuator 24 is the same, the time during which the needle valve 13 is opened becomes longer as the pressure of the working liquid supplied into the pressure control chamber 16 becomes lower. For this reason, the lower the pressure of the working liquid supplied to the pressure control chamber 16, the longer the time during which the fuel is injected, and the fuel injection amount increases. In other words, the higher the pressure of the working liquid, the shorter the time during which the needle valve 13 is open, and the smaller the fuel injection amount.

  In the fuel injection device of the present embodiment, the pressure of the working liquid supplied to the pressure control chamber 16 when the control valve 25 is closed is detected, and the solenoid actuator 24 is energized based on the detected pressure of the working liquid. Adjust the time. In the present embodiment, correction is performed to increase the energization time as the pressure of the working liquid increases.

  Furthermore, the fuel injection device in the present embodiment detects the temperature of the working liquid supplied to the fuel injection valve, and adjusts the energization time of the solenoid actuator 24 based on the detected temperature of the working liquid.

  Referring to FIG. 2, when the temperature of the working liquid rises, the viscosity of the working liquid decreases. When the viscosity of the working liquid decreases, the working liquid is easily discharged from the pressure control chamber 16 when the control valve 25 is opened. An outlet-side orifice 23 that restricts the flow rate of the working liquid is disposed at the outlet of the pressure control chamber 16, but the flow rate of the working liquid discharged from the pressure control chamber 16 increases as the temperature of the working liquid increases. That is, the response when the control valve 25 is opened is improved, and the rate of decrease in the pressure inside the pressure control chamber 16 is increased. The time when the pressure in the pressure control chamber 16 reaches the valve opening pressure is advanced. As a result, the time during which fuel is injected becomes longer, and the amount of fuel injection becomes larger. For this reason, in the present embodiment, the correction is made so that the amount of injected fuel is reduced as the temperature of the working liquid increases. That is, correction is performed to shorten the energization time of the solenoid actuator as the temperature of the working liquid increases.

  FIG. 5 shows a flowchart of control when fuel is injected in the fuel injection device according to the present embodiment.

  In step 111, the pressure of the working liquid supplied to the fuel injection valve and the pressure of the fuel are detected. Referring to FIG. 1, in the internal combustion engine of the present embodiment, the pressure of the working liquid can be detected by pressure sensor 74. The fuel pressure can be detected by the pressure sensor 64. The detection of the pressure of the working liquid and the pressure of the fuel is not limited to this form, and can be detected by any method. For example, it may be detected in advance at predetermined intervals and the average value may be adopted.

  Next, in step 112, a required single fuel injection amount is set. As for the fuel injection amount to be supplied to the combustion chamber, for example, a map of the fuel injection amount that is a function of the required load and the engine speed can be stored in the electronic control unit 30 in advance. With reference to FIG. 1, the required load can be detected by the output of the load sensor 41, and the engine speed can be detected by the output of the crank angle sensor 42. The fuel injection amount required by the map can be set based on the detected required load and engine speed.

  Next, in step 113, a reference energization time TLB for energizing the solenoid actuator 24 of the fuel injection valve 3 is set. The energization time of the solenoid actuator 24 can be set longer as the required fuel injection amount increases. Further, the fuel supplied to the fuel injection valve 3 is supplied to the nozzle chamber 17 and urges the needle valve 13 in the valve opening direction. As the pressure of the fuel supplied to the fuel injection valve 3 increases, the force that urges the needle valve 13 in the valve opening direction increases. Furthermore, the fuel injection quantity per unit time injected from the nozzle hole 11 increases as the fuel pressure increases. For this reason, the energization time of the solenoid actuator 24 can be set shorter as the fuel pressure increases.

  FIG. 6 shows a map for setting the reference energization time in the present embodiment. A map of the reference energization time TLB that is a function of the required fuel injection amount and fuel pressure can be stored in advance in the electronic control unit 30. Referring to FIG. 5, reference energization time TLB can be set by using a map based on the required fuel injection amount set in step 112 and the fuel pressure detected in step 111.

  Next, in step 114, a correction term TLMP for the working fluid pressure with respect to the reference energization time TLB is set. In the present embodiment, the reference energization time is corrected based on the detected pressure of the working liquid. As described above, the higher the pressure of the working liquid supplied to the pressure control chamber 16, the shorter the time during which the needle valve 13 is open. The working liquid pressure correction term TLMP in the present embodiment is set so that the energization time of the solenoid actuator 24 becomes longer as the pressure of the working liquid increases.

  FIG. 7 shows a map for setting a correction term for the working fluid pressure in the present embodiment. In the present embodiment, a correction term for the energization time is set based on the fuel injection amount in addition to the pressure of the working liquid. The energization time correction term TLMP relating to the working liquid pressure can be set by a map having a function of the working liquid pressure and the fuel injection amount. The map shown in FIG. 7 can be stored in the electronic control unit 30 in advance. Based on the detected pressure of the working liquid and the required fuel injection amount, the correction term TLMP of the working liquid pressure related to the energization time can be set.

  Referring to FIG. 5, next, in step 115, the temperature of the working liquid is detected. Referring to FIG. 1, in the present embodiment, temperature sensor 75 can detect the temperature of the working liquid.

  Next, in step 116, a correction term TLMT for the working liquid temperature with respect to the reference energization time TLB is set. A correction term TLMT for the working liquid temperature, which is a function of the temperature of the working liquid, can be stored in the electronic control unit 30 in advance. Based on the detected temperature of the working liquid, the energization time correction term TLMT related to the working liquid temperature can be set. The working liquid temperature correction term TLMT of the present embodiment is set so that the energization time of the solenoid actuator becomes shorter as the temperature of the working liquid becomes higher.

  Next, in step 117, a corrected energization time TLFIN of the solenoid actuator is calculated. In the present embodiment, the corrected energization time TLFIN of the solenoid actuator after correction is calculated by adding the correction term TLMP relating to the working liquid pressure and the correction term TLMT relating to the working liquid temperature to the reference energization time TLB. .

  In this way, it is possible to correct the energization time of the solenoid actuator. The correction of the energization time of the solenoid actuator is not limited to addition or subtraction of a correction term, and any correction method can be adopted. For example, the corrected energization time may be calculated by multiplying the reference energization time of the solenoid actuator by the pressure correction term and the temperature correction term.

  Next, in step 118, the energization start time ETST is set. In the example of FIG. 3, energization is started at the crank angle θ1, but there is a predetermined time delay until the crank angle θ2 at which fuel is actually injected. The energization start timing ETST can be set by arbitrary control in consideration of this time delay. For example, the reference fuel injection start timing is set based on the engine speed and the required load. The energization start timing ETST can be set by previously setting a time delay from the start of energization to the start of fuel injection and subtracting the time delay from the reference fuel injection start timing.

  Referring to FIG. 5, in step 119, energization end timing ETEN is calculated. The energization end timing ETEN can be calculated by adding the corrected energization time TLFIN of the actuator to the energization start timing EST.

  Next, in step 120, the actuator is energized according to the set energization start timing ETST and energization end timing ETEN. The energization start timing, energization time, and energization end timing may be controlled based on the crank angle, or based on the elapsed time from the reference time point.

  Thus, the fuel injection device of the present embodiment adjusts the energization time of the solenoid actuator based on the fuel pressure and the working liquid pressure. By performing this control, it is possible to suppress the deterioration of the accuracy of the fuel injection amount due to the pressure fluctuation of the working liquid and to bring the fuel injection amount close to a desired amount. That is, the accuracy of the fuel injection amount is improved.

  In particular, in the fuel injection valve of the present embodiment, the working liquid and the fuel for controlling the opening and closing of the needle valve are different, and each is individually supplied to the fuel injection valve. When the fuel and the working liquid are the same fuel injection device, the internal pressure of the pressure control chamber is equal to the internal pressure of the nozzle chamber. However, when the working liquid is composed of a liquid different from the fuel as in the fuel injection valve of the present embodiment, the fuel injection amount is determined under the influence of the pressure of each liquid. The effect of liquid pressure increases. For this reason, the fuel injection device of the present embodiment is particularly useful for an internal combustion engine in which the fuel and the working liquid are different from each other.

By controlling the injection amount of the fuel supplied to the combustion chamber with high accuracy, the torque output from the internal combustion engine can be controlled with high accuracy. For this reason, the responsiveness with respect to a driver | operator's intention, ie, drivability, can be improved. Moreover, the quality of the exhaust gas flowing out from the combustion chamber can be improved by controlling the injection amount of the fuel supplied to the combustion chamber with high accuracy. For example, since the air-fuel ratio at the time of combustion can be controlled more accurately by controlling the fuel injection amount with high accuracy, it is possible to suppress an increase in the amount of NO _x discharged from the combustion chamber.

  The fuel injection amount required based on the operating state of the internal combustion engine varies depending on the fuel used, the type of internal combustion engine, the required exhaust properties, and the like. For this reason, it is preferable that the required fuel injection amount is appropriately set according to the fuel used.

  Furthermore, the fuel injection device in the present embodiment sets the energization time of the actuator based on the temperature of the working liquid. In the fuel injection device of the present embodiment, control is performed to correct the energization time of the actuator to be shorter as the temperature of the working liquid increases. By performing this control, it becomes possible to control the fuel injection amount more accurately, and it is possible to improve drivability and exhaust properties.

  The internal combustion engine in the present embodiment has been described by exemplifying a spark ignition type internal combustion engine having an ignition plug. However, the internal combustion engine is not limited to this form, and the present invention is also applied to a compression self-ignition internal combustion engine having no ignition plug. The invention can be applied.

  Moreover, although the internal combustion engine in this Embodiment employ | adopts gaseous fuel, it is not restricted to this form, You may employ | adopt liquid fuel. For example, the present invention can be applied to a fuel injection device for a diesel engine. High pressure fuel may be supplied to the common rail (fuel accumulator) from a fuel tank of liquid fuel different from the working liquid by a fuel pump, and high pressure fuel may be supplied to the fuel injection valve from the common rail.

  In the present embodiment, the fuel injection valve that directly injects fuel into the combustion chamber has been described as an example. However, the present invention is not limited to this mode. For example, a premixed internal combustion engine that injects fuel into the intake port. The fuel injection device of the present invention can also be adopted for the engine.

  The above embodiments can be combined as appropriate. In addition, the order of the steps included in the above-described control can be changed as appropriate as long as the function and action do not change. In the respective drawings described above, the same or equivalent parts are denoted by the same reference numerals. In addition, said embodiment is an illustration and does not limit invention. In the embodiment, the change shown in a claim is included.

2 Combustion chamber 3 Fuel injection valve 11 Injection hole 13 Needle valve 16 Pressure control chamber 17 Nozzle chamber 18 Working liquid supply passage 19 Fuel supply passage 21 Working liquid discharge passage 22 Inlet side orifice 23 Outlet side orifice 24 Solenoid actuator 25 Control valve 30 Electron Control unit 40 Accelerator pedal 41 Load sensor 42 Crank angle sensor 63 Fuel supply pipe 64 Pressure sensor 70 Working fluid 71 Working fluid tank 73 Working fluid supply pipe 74 Pressure sensor 75 Temperature sensor

Claims (3)

A fuel injection valve whose opening and closing is controlled by a working liquid;
A fuel supply device for supplying pressurized fuel to the fuel injection valve;
A working liquid supply device for supplying a pressurized working liquid to the fuel injection valve;
The working liquid supply device is formed to supply a working liquid different from the fuel,
The fuel injection valve is formed so as to open and close the pressure control chamber for storing the working liquid, the control valve for opening and closing the pressure control chamber, the control valve driving device for driving opening and closing of the control valve, and the injection hole for injecting fuel. And an opening / closing member that closes the nozzle hole by being pressed by the pressure inside the pressure control chamber,
By energizing the control valve drive device, the control valve is opened, the pressure in the pressure control chamber is lowered, the opening and closing member is moved and fuel is injected,
The energization time of the control valve driving device that detects the pressure of the fuel supplied to the fuel injection valve and the pressure of the working liquid and determines the time during which the fuel is injected from the fuel injection valve based on the pressure of the fuel and the pressure of the working liquid A fuel injection device for an internal combustion engine, characterized in that The fuel injection device for an internal combustion engine according to claim 1, wherein the energization time is set longer as the pressure of the working liquid increases. The fuel injection device for an internal combustion engine according to claim 1 or 2, wherein the temperature of the working liquid supplied to the fuel injection valve is detected, and the energization time is set shorter as the temperature of the working liquid increases.

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