JP2017145756A - Internal combustion engine and fuel injection control method for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine that: has a fuel injection device including a three-way valve located between a high-pressure side fuel flow passage, a low-pressure side fuel flow passage and a control chamber for controlling a needle vertically; can correct variation of fuel injection amount from the fuel injection device due to a temperature of a wall surface in the vicinity of an orifice through which the fuel passes when it is caused to flow out from the control chamber of the fuel injection device to the low-pressure side fuel flow passage; and as a result, can highly accurately perform fuel injection control, and also to provide a fuel injection control method for the internal combustion engine.SOLUTION: In an operation of an internal combustion engine, inspection control is performed for switching to a state where a control chamber 10 and a low-pressure side fuel flow passage 16 are communicated with each other when fuel is not being injected from a fuel injection device 1 and returning to a state where the control chamber 10 and a high-pressure side fuel flow passage 15 are communicated with each other before the fuel injection is started. Based on correction physical quantities Vmax, ΔV, ta obtained from a state of the fuel F flowing out to the low-pressure side fuel flow passage 16 during the inspection control, valve opening time of a fuel injection valve 1 during the fuel injection is corrected.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an internal combustion engine including a combustion injection device having a three-way valve between a high pressure side fuel flow path, a low pressure side fuel flow path, and a control chamber for controlling up and down of a needle, and a fuel injection control method for the internal combustion engine.

  A fuel injection device is provided in a combustion chamber of an internal combustion engine mounted as a power source of an automobile or the like. As this fuel injection device, conventionally, a control chamber that flows in fuel from a high-pressure side fuel flow path connected to a common rail or the like, and flows out into a low-pressure side fuel flow path connected to a fuel return path or the like, and a low-pressure side 2. Description of the Related Art A two-way valve type fuel injection device composed of a two-way valve provided in a fuel flow path and a needle with a command piston provided in a lower part of a control chamber has been used.

  In this two-way valve type fuel injection device, when the fuel is not injected, the two-way valve is closed so that the fuel in the control chamber does not flow out, and the pressure of the fuel in the control chamber added to the upper part of the needle is increased. By maintaining the downward force of the pressure and the spring force of the spring larger than the upward force due to the pressure of the fuel applied to the lower portion of the needle, the needle is pushed down to close the injection hole.

  On the other hand, when injecting the fuel, the two-way valve is opened, the fuel in the control chamber is caused to flow out, the fuel pressure in the control chamber is reduced, and a downward force is applied to the lower part of the needle. By making it smaller than the force, the needle is moved upward to open the injection hole.

  However, in this two-way valve type fuel injection device, the high-pressure side fuel flow path and the low-pressure side fuel flow path communicate with each other via the control chamber by opening the two-way valve during fuel injection. Therefore, the flow rate of the fuel flowing out (leaking) from the control chamber to the low pressure side fuel flow path increases, and the amount of heat generated due to the decrease in the pressure of the fuel at the time of the outflow increases, so that the fuel injection device and the fuel There was a problem of high temperatures. There is also a problem that the load on the fuel pump increases.

  Therefore, in recent years, as shown in FIG. 1, a three-way valve (in FIG. 1) is formed at the intersection of a high-pressure side fuel passage 15 connected to a common rail or the like, a low-pressure side fuel passage 16, and a passage 16 a leading to the control chamber 10. There is provided a three-way valve type fuel injection device provided with a solenoid type control valve 11) for switching the communication state between the control chamber 10 and the high pressure side fuel flow path 15 and the communication state between the control chamber 10 and the low pressure side fuel flow path 16. It has come to be used.

  In this three-way valve type fuel injection device, when the fuel is not injected, the control chamber 10 and the high-pressure side fuel flow path 15 are brought into communication with each other by not energizing the solenoid control valve 11 and applied to the upper portion of the needle 13. By making the downward force due to the pressure of the fuel F in the chamber 10 and the elastic force of the elastic member 12 larger than the upward force due to the pressure of the fuel F in the fuel storage chamber 14 applied to the lower part of the needle 13, the injection hole 17 is formed by the needle 13. To close the valve.

  On the other hand, when injecting the fuel, the solenoid control valve 11 is energized to bring the control chamber 10 and the low-pressure side fuel flow path 16 into communication, and the fuel F flows out of the control chamber 10, By making the downward force due to the pressure of the fuel F in the control chamber 10 applied to the elastic member 12 and the elastic force of the elastic member 12 smaller than the upward force due to the pressure of the fuel F in the fuel storage chamber 14 applied to the lower part of the needle 13, The valve is opened away from the injection hole 17.

  That is, in the three-way valve type fuel injection device, unlike the two-way valve type fuel injection device, between the high-pressure side fuel flow path 15 and the control chamber 10, or the low-pressure side fuel flow path 16 and the control chamber 10 Since the high pressure side fuel flow path 15 and the low pressure side fuel flow path 16 do not communicate with each other in a communicating state, the fuel F flowing out from the control chamber 10 to the low pressure side fuel flow path 16 The flow rate is reduced.

  However, in this three-way valve type fuel injection device, conversely, since the flow rate of the fuel F flowing out from the control chamber 10 to the low pressure side fuel flow path 16 is small, the amount of heat generated due to the decrease in the fuel pressure is small. There is a problem that the temperature of the fuel injection device is difficult to rise to an appropriate temperature range.

  Here, when the control chamber 10 and the low pressure side fuel flow channel 16 communicate with the outlet of the control chamber 10 communicated with the low pressure side fuel flow channel 16, the pressure inside the control chamber 10 is reduced. In order to prevent the fuel pressure from gradually decreasing by preventing the pressure from rapidly decreasing to 16, the orifice 16a serving as a throttle is provided. The flow rate of the fuel F passing through the orifice 16a changes due to the friction of the wall surface of the passage portion where the orifice 16a exists, and the magnitude of the friction changes according to the temperature of the wall surface. That is, the flow rate of the fuel F passing through the orifice 16a changes according to the temperature of the wall surface in the vicinity of the orifice 16a.

  When the temperature of the wall surface is low, the wall friction increases, the flow rate of the fuel F passing through the orifice 16a decreases, and the pressure drop of the fuel F in the control chamber 10 is delayed. As a result, the speed at which the needle 13 is separated from the injection hole 17 is reduced, and the timing for starting injection is also delayed. On the other hand, when the fuel injection is stopped, the fuel F stops passing through the orifice 16a, so that it is not affected by wall friction and wall temperature.

  Therefore, when the wall surface temperature is low, the fuel injection amount from the injection hole 17 of the fuel injection device is larger than the standard fuel injection amount corresponding to the energization time (indicated pulse width in duty control) to the solenoid type control valve 11. It will decrease. When the wall surface temperature is high, the reverse phenomenon occurs, and the fuel injection amount becomes larger than the standard fuel injection amount even during the same energization time.

  In other words, the fuel injection amount (fuel injection rate) from the fuel injection device 1 varies due to the temperature of the wall surface in the vicinity of the orifice 16 a of the low pressure side fuel flow path 16 from the control chamber 10. As a result, there has been a problem that the operating efficiency of the internal combustion engine deteriorates.

  On the other hand, in a fuel injection device having pressure accumulating means such as a common rail, in order to specify which cylinder fuel injection device has a fuel leak, the fuel is connected between the pressure accumulating means and the injector, and the fuel from the pressure accumulating means to the injector Provided with a flow limiter that is shut off when the flow amount of the fuel exceeds a predetermined value, when the engine is operating and the injector does not inject fuel, or between the injection and the next injection. During the non-injection period, the needle is lifted by switching the electromagnetic switching valve for a time shorter than the time when injection is performed by the injector, and the fuel is leaked by a flow rate less than the flow rate of the flow limiter. If the sum of the fuel leak amount and the flow rate of the fuel is greater than the flow rate of the flow limiter, the leakage is Fuel leakage detecting device to stop the supply of fuel to the injector has been proposed (e.g., see Patent Document 1).

Japanese Patent Laid-Open No. 09-042105

  The present invention has been made in view of the above, and an object of the present invention is to provide a combustion injection apparatus having a three-way valve between a high pressure side fuel flow path, a low pressure side fuel flow path, and a control chamber for controlling the up and down of the needle. In the internal combustion engine having the above, the variation in the fuel injection amount from the fuel injection device due to the temperature of the wall surface near the orifice that passes when the fuel flows out from the control chamber of the fuel injection device to the low pressure side fuel flow path can be corrected. As a result, an object of the present invention is to provide an internal combustion engine capable of performing fuel injection control with high accuracy, and a fuel injection control method for the internal combustion engine.

  In order to achieve the above object, an internal combustion engine of the present invention includes a control chamber that flows in fuel from a high-pressure side fuel flow path and flows out of fuel from a low-pressure side fuel flow path, the control chamber, and the high-pressure side fuel flow path. A fuel injection device having a three-way valve that switches between a first communication state in which the control chamber communicates with a second communication state in which the control chamber and the low-pressure side fuel flow path communicate with each other, and a control device includes the three-way valve of the fuel injection device When the fuel is not injected, the valve is switched to the first communication state and the injection hole is closed with the needle. When the fuel is injected, the valve is switched to the second communication state and the needle is separated from the injection hole to open the injection hole. In the internal combustion engine, when the control device switches the three-way valve from the first communication state to the second communication state with respect to the operating state of the internal combustion engine, the needle is separated from the injection hole from this switching time point. Then, when a test time shorter than the injection standby time until fuel injection is started is set and fuel is not injected from the fuel injection device, the three-way valve is changed from the first communication state to the second communication state. After the inspection time has elapsed after switching, inspection control is performed to return the three-way valve from the second communication state to the first communication state, and the state of the fuel that has flowed into the low-pressure side fuel flow path during the inspection control On the basis of the physical quantity for correction obtained from the above, the control for correcting the control amount of the three-way valve at the time of fuel injection is performed.

  That is, before the fuel injection from the fuel injection device is performed, the three-way valve is in the second communication state only for a minute inspection time so that the needle is not separated from the injection hole, that is, the fuel injection is not performed. Thus, inspection control is performed to allow fuel to flow out (leak) from the control chamber to the low-pressure side fuel flow path. In this inspection control, a physical quantity obtained from the state of the fuel flowing out to the low-pressure side fuel flow path is detected as a correcting physical quantity.

  The parameter that is the physical quantity for correction is a parameter that changes according to the temperature of the portion of the fuel flowing out from the control chamber to the low pressure side fuel flow path, particularly the wall surface near the orifice that affects the fuel flow rate, It is preferable that the parameter can sensitively reflect the change in the fuel flow rate in the low-pressure side fuel flow path. More specifically, it is a physical quantity such as the maximum flow rate per unit time, the rate of change of the flow rate of fuel, the timing at which the outflow of fuel starts, etc., obtained from the time series of the flow rate of fuel flow measured by the fuel flow rate sensor.

  Based on the estimated and calculated parameters, the control amount of the three-way valve at the time of fuel injection from the fuel injection device, for example, when the three-way valve is opened by energizing the solenoid, the energization time is corrected.

  Therefore, according to this configuration, it is possible to correct the variation in the fuel injection amount from the fuel injection device due to the temperature of the wall surface in the vicinity of the orifice of the low-pressure side fuel flow path through which the fuel passes. Control can be performed with high accuracy.

  Further, in the internal combustion engine, the control device uses the physical quantity obtained from the state of the fuel at the time of the inspection control as the maximum flow rate of fuel per unit time, the rate of change of the fuel flow rate, or the start of fuel outflow. Any one or a combination of timings, and at the time of fuel injection from the fuel injection device, based on these physical quantities, a correction time related to the valve opening time of the control amount of the three-way valve is calculated. Then, when the three-way valve is controlled with the corrected valve opening time calculated by adding the calculated correction time to the basic valve opening time, the fuel can be obtained with a relatively simple algorithm. The variation in the fuel injection amount from the fuel injection device due to the temperature of the wall surface in the vicinity of the orifice of the low pressure side fuel flow path through which the gas passes can be corrected.

  In addition, a fuel injection control method for an internal combustion engine according to the present invention for achieving the above object includes a control chamber in which fuel flows in from a high-pressure side fuel flow path and fuel flows out from a low-pressure side fuel flow path, and the control chamber A fuel injection device having a three-way valve that switches between a first communication state in which the high-pressure side fuel flow path communicates and a second communication state in which the control chamber communicates with the low-pressure side fuel flow path, When the fuel is not injected, the three-way valve of the fuel injection device is switched to the first communication state to close the injection hole with the needle, and when fuel is injected, the needle is separated from the injection hole by switching to the second communication state. In the fuel injection control method for an internal combustion engine that opens the injection hole, when the three-way valve is switched from the first communication state to the second communication state with respect to the operating state of the internal combustion engine, An inspection time shorter than an injection waiting time until the fuel is started after the dollar is separated from the injection hole is set, and when the fuel is not injected from the fuel injection device, the three-way valve is connected to the first communication port. After the inspection time is switched from the state to the second communication state, the inspection control for returning the three-way valve from the second communication state to the first communication state is performed, and the low-pressure side fuel flow is performed during the inspection control. In this method, the control amount of the three-way valve at the time of fuel injection is corrected based on a physical quantity for correction obtained from the state of fuel that has flowed out to the road.

  Further, in the fuel injection control method for an internal combustion engine, the physical quantity obtained from the state of the fuel at the time of the inspection control is determined based on the maximum flow rate per unit time of the fuel, the rate of change of the fuel flow rate, or the outflow of the fuel. Any one or a combination of timings, and at the time of fuel injection from the fuel injection device, based on these physical quantities, a correction time related to the valve opening time of the control amount of the three-way valve is calculated. Then, the three-way valve is controlled with the post-correction valve opening time calculated by adding the calculated correction time to the basic valve opening time.

  According to these methods, the same effects as the above-described internal combustion engine can be achieved.

  According to the internal combustion engine and the fuel injection control method of the internal combustion engine of the present invention, the combustion injection device having the three-way valve is provided between the high pressure side fuel flow path, the low pressure side fuel flow path, and the control chamber for controlling the up and down of the needle. In the internal combustion engine, it is possible to correct the variation in the fuel injection amount from the fuel injection device due to the temperature of the wall surface in the vicinity of the orifice that passes when flowing out from the control chamber of the fuel injection device to the low pressure side fuel flow path. As a result, fuel injection control can be performed with high accuracy.

It is a figure which shows typically the structure of the fuel-injection apparatus used with the internal combustion engine of embodiment which concerns on this invention, and shows the state which the control chamber and the high voltage | pressure side fuel flow path are connecting. It is a figure showing the composition of the fuel injection device used with the internal-combustion engine of the embodiment concerning the present invention typically, and the state where the control room and the low-pressure side fuel channel are connected. It is a figure which shows the control flow of the fuel-injection control method of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows the time change of the flow volume of the fuel which flows through the low voltage | pressure side fuel flow path at the time of inspection control.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention and a fuel injection control method for the internal combustion engine will be described with reference to the drawings. As shown in FIG. 1, a fuel injection device 1 used in an internal combustion engine according to an embodiment of the present invention includes a control chamber 10, a solenoid-type control valve 11 (11a is a solenoid) constituting a three-way valve, and an attachment. A force spring (elastic member) 12, a needle 13, and a fuel storage chamber 14 are provided.

  The control chamber 10 is a chamber through which the fuel F flows from the high pressure side fuel flow path 15 and flows out from the low pressure side fuel flow path 16. The solenoid control valve 11 includes a first communication state in which the control chamber 10 and the high-pressure side fuel flow path (left hatched portion in FIG. 1) communicate with each other, and the control chamber 10 and the low-pressure side fuel flow path (right hatched in FIG. 1). Part) is a three-way valve that switches between a second communication state in which 16 communicates. The biasing spring 12 is a spring that pushes the needle 13 from above the needle 13. The needle 13 is a device that closes or separates the injection hole 17 from the injection hole 17 in accordance with the operating state of the solenoid control valve 11. The fuel storage chamber 14 is a chamber that is adjacent to the lower portion of the needle 13 and the injection hole 17 and communicates with the high-pressure side fuel flow path 15.

  Further, when the control chamber 10 and the low pressure side fuel flow path 16 communicate with the outlet of the control chamber 10 communicated with the low pressure side fuel flow path 16, the pressure inside the control chamber 10 is reduced to the low pressure side fuel flow path 16. In order to prevent the fuel pressure from gradually decreasing while preventing the pressure from rapidly decreasing, an orifice 16a serving as a throttle is provided.

  Moreover, the control apparatus 40 which controls the fuel-injection apparatus 1 of the internal combustion engine of this invention is provided. The control device 40 is based on signals transmitted from various sensors related to the operating state of the internal combustion engine, such as an accelerator opening sensor (not shown) and an engine speed detection sensor (not shown). This is a device for controlling a solenoid type control valve 11).

  Here, the operation state of the fuel injection device 1 when the fuel is not injected, in other words, when the solenoid control valve 11 is not energized and when it is energized will be described. When the fuel is not injected, the solenoid-type control valve 11 is not energized, and when the control chamber 10 and the high-pressure side fuel flow path 15 are switched to the first communication state as shown in FIG. Since the pressure of the fuel F in the control chamber 10 applied to the upper part and the elastic force of the urging spring 12 are larger than the pressure of the fuel F in the fuel storage chamber 14 applied to the lower part of the needle 13, the needle 13 is pushed down. Thus, the injection hole 17 is closed, and the fuel F stored in the fuel storage chamber 14 is not injected outside (combustion chamber (not shown), exhaust passage (not shown), etc.) from the injection hole 17.

  When injecting fuel, when the solenoid control valve 11 is energized, the control chamber 10 is switched to the second communication state in which the control chamber 10 and the low-pressure side fuel flow path 16 are in communication as shown in FIG. The fuel F flows into the lower pressure side fuel flow path 16, and the pressure of the fuel F in the control chamber 10 applied to the upper part of the needle 13 and the elastic force of the biasing spring 12 are applied to the lower part of the needle 13. Since the pressure is lower than the pressure of the fuel F, the needle 13 is separated from the injection hole 17 to open the injection hole 17, and the fuel F stored in the fuel storage chamber 14 is injected outside through the injection hole 17.

  In the internal combustion engine according to the embodiment of the present invention, the control device 40 energizes the solenoid control valve 11 with respect to the operation state of the internal combustion engine to switch from the first communication state to the second communication state. In this case, an inspection time shorter than the injection standby time from the time of switching until the needle 13 is separated from the injection hole 17 and fuel injection is started is set.

  In other words, the fuel reservoir chamber in which the pressure of the fuel F in the control chamber 10 applied to the upper portion of the needle 13 and the elastic force of the biasing spring 12 are applied to the lower portion of the needle 13 from the time when energization of the solenoid control valve 11 is started. The time when the pressure of the fuel F becomes smaller than the pressure of the fuel 14 and the needle 13 is separated from the injection hole 17 is defined as an injection standby time. The inspection time is shorter than the injection waiting time, that is, the fuel in the fuel storage chamber 14 where the pressure of the fuel F in the control chamber 10 applied to the upper portion of the needle 13 and the elastic force of the biasing spring 12 are applied to the lower portion of the needle 13. It is assumed that the time is larger than the pressure of F.

  The injection standby time varies depending on the operating state of the internal combustion engine, but can be obtained in advance by experiments or the like. The inspection time is set to be shorter than the injection standby time. Preferably, in order to simplify the control, it is preferable to set the inspection time so as to be shorter than the injection standby time even in the widest possible operating state of the internal combustion engine. However, if the inspection time is too short, the accuracy of the physical quantity for correction described later may be reduced. In this case, the inspection time may be changed according to the operating state of the internal combustion engine.

  When the fuel injection device 1 is not injecting fuel, the solenoid-type control valve 11 is energized to switch from the first communication state to the second communication state. Inspection control for stopping energization of the control valve 11 and returning from the second communication state to the first communication state is performed. In this inspection control, the fuel F flows out (leaks out) from the control chamber 10 to the low pressure side fuel flow path 16, but when the inspection time elapses, before the needle 13 moves away from the injection hole 17, the solenoid control valve 11 is moved to. Therefore, the fuel injection from the fuel injection device 1 to the combustion chamber is not performed.

  During this inspection control, the energization time (control) of the solenoid type control valve (three-way valve) 11 at the time of fuel injection based on the physical quantity for correction obtained from the state of the fuel F flowing out to the low pressure side fuel flow path 16 (Amount) is corrected.

  Specifically, the flow rate V of the fuel F flowing out from the control chamber 10 into the low pressure side fuel flow path 16 is detected by the flow meter 20 provided in the low pressure side fuel flow path 16, and the detected flow rate V of the fuel F is detected. 4 is stored in the control device 40 as time-series data indicating the change in the flow rate V of the fuel F with respect to the elapsed time t at the time of inspection control as shown in FIG.

  Then, the control device 40 uses the time series data of the flow rate V of the fuel F created based on the detection value of the flow meter 20 as a physical quantity for correction obtained from the state of the fuel at the time of inspection control. The maximum flow rate Vmax (point A in FIG. 4), which is the maximum flow rate per unit time, of the fuel F that has flowed into the low-pressure side fuel flow path 16 from 10, or a flow rate change rate ΔV (change in FIG. 4 or the outflow start timing ta (C point in FIG. 4) at which the outflow of the fuel F starts.

  The maximum flow rate Vmax, the flow rate change rate ΔV, and the outflow start timing ta of these parameters change according to the temperature of the wall surface in the vicinity of the orifice 16 a that passes when the control chamber 10 flows out to the low-pressure side fuel flow path 16. It is. If the temperature of the wall surface is high, the viscosity of the fuel F on the wall surface decreases and the fuel F easily flows. Therefore, the maximum flow rate Vmax and the flow rate change rate ΔV increase, and the outflow start timing ta of the parameter is Get early. On the other hand, when the temperature of the wall surface is low, the viscosity of the fuel F on the wall surface increases and the fuel F becomes difficult to flow. Therefore, the maximum flow rate Vmax and the flow rate change rate ΔV become small, and the outflow start timing ta of the parameter is delayed. Become.

  Then, the control device 40 outputs from the fuel injection device 1 based on any one or some combination of the maximum flow rate Vmax, the flow rate change rate ΔV, and the outflow start timing ta, which are physical quantities for correction. Control is performed to correct the basic energization time Tb, which is the energization time of the solenoid control valve 11 at the time of fuel injection (indicated pulse width in duty control).

  That is, when fuel is injected from the fuel injection device 1, energization among control amounts such as the current, voltage magnitude, and energization time of the solenoid type control valve (three-way valve) 11 is based on these correction physical quantities. A corrected time Tc relating to time (valve opening time) is calculated, and the calculated correction time Tc is calculated by adding the calculated correction time Tc to the basic energizing time (basic valve opening time) Tb. The energization time of the solenoid control valve 11 is controlled at time Td (= Tb + Tc). Thereby, it is possible to correct the variation in the fuel injection amount from the fuel injection device 1 due to the temperature of the wall surface in the vicinity of the orifice 16a of the low-pressure side fuel flow path 16 through which the fuel passes by a relatively simple algorithm.

  Note that the relationship between the correction time Tc and any one or some combination of the maximum flow rate Vmax, the flow rate change rate ΔV, or the outflow start timing ta and the control device 40 in a map data format or a function or the like in advance through experiments or the like. Thus, the correction time Tc can be easily calculated from preset map data, function, etc. from the maximum flow rate Vmax, flow rate change rate ΔV, outflow start timing ta, etc. detected by the inspection control. it can.

  In other words, the control chamber 10 in which fuel flows in from the high-pressure side fuel flow path 15 and out of fuel from the low-pressure side fuel flow path 16, and the control chamber 10 and the high-pressure side fuel flow path 15 or A solenoid-type control valve 11 for switching the communication state of the low-pressure side fuel flow path 16, an elastic member 12 provided inside the control chamber 10, a needle 13 adjacent to the lower portion of the control chamber 10, and a lower portion of the needle 13 A fuel storage chamber 14 that communicates with the high-pressure side fuel flow path 15 is provided adjacent to the injection hole 17.

  Further, when the control chamber 10 and the high-pressure side fuel flow path 15 are in communication with each other without energizing the solenoid control valve 11, the pressure of the fuel F in the control chamber 10 applied to the upper portion of the needle 13 and the elastic member 12. Since the elastic force becomes larger than the pressure of the fuel F in the fuel storage chamber 14 applied to the lower part of the needle 13, the injection hole 17 is closed by the needle 13, and the fuel stored in the fuel storage chamber 14 is externally supplied from the injection hole 17. Do not spray.

  On the other hand, when the solenoid-type control valve 11 is energized and the control chamber 10 and the low-pressure side fuel flow path 16 are in communication with each other, fuel flows out of the control chamber 10 into the low-pressure side fuel flow path 16 and the needle 13 The pressure of the fuel F in the control chamber 10 applied to the upper portion and the elastic force of the elastic member 12 become smaller than the pressure of the fuel F in the fuel storage chamber 14 applied to the lower portion of the needle 13, thereby separating the needle 13 from the injection hole 17. Thus, the fuel F stored in the fuel storage chamber 14 is injected outside through the injection hole 17.

  Further, the control device 40 for controlling the solenoid control valve 11 is connected to the solenoid control valve 11 before the fuel injection from the fuel injection device 1 set in advance according to the operating state of the internal combustion engine. 13 is energized only for a preset inspection time so as not to be separated from the injection hole 17, and inspection control is performed for a very short time in which the control chamber 10 and the low-pressure side fuel flow path 16 are in communication with each other. The maximum flow rate Vmax, which is the maximum flow rate per unit time, of the fuel F that has flowed out into the lower pressure side fuel flow path 16, or the flow rate change rate ΔV indicating the change in the flow rate V of the fuel F, or the outflow of the fuel F starts. The outflow start timing ta is calculated, and at the time of fuel injection from the fuel injection device 1 based on the calculated maximum flow rate Vmax, flow rate change rate ΔV, outflow start timing ta, or the like. Control is performed to correct the basic energization time, which is the energization time of the solenoid type control valve 11.

  Next, a control method for a fuel injection device for an internal combustion engine according to the present invention based on the configuration of the fuel injection device for the internal combustion engine will be described with reference to the control flow of FIG. This control flow is shown as a control flow called from an advanced control flow every time a preset control time elapses when the internal combustion engine is in an operating state.

  The control flow of FIG. 3 will be described. When this control flow starts, it is determined in step S10 whether or not fuel injection from the fuel injection device 1 will be performed recently. That is, the timing at which fuel is injected from the fuel injection device 1 is set according to the operating state of the internal combustion engine, and this injection timing can be known, so it is determined whether or not it is immediately before this fuel injection timing. When it is determined that fuel injection from the fuel injection device 1 will not be performed recently (NO), the process proceeds to return, and this control flow ends. When it is determined that fuel injection from the fuel injection device 1 will be performed recently (YES), the process proceeds to step S20, and the needle 13 is separated from the injection hole 17 to the solenoid control valve 11 in step S20. In such a case, the control chamber 10 and the low-pressure side fuel passage 16 are in communication with each other only during a preset inspection time so that the fuel F flows out (leaks out) from the control chamber 10 into the low-pressure side fuel passage 16. Take control. At this time, the flow rate of the fuel F flowing out from the control chamber 10 to the low pressure side fuel flow path 16 is detected by the flow meter 20, and the data of the detected value is time-series data as shown in FIG. 40. After performing the control of step S20, the process proceeds to step S30.

  In step S30, based on the time-series data obtained in step S20, the maximum flow rate Vmax (point A in FIG. 4), which is the maximum flow rate per unit time of the fuel F that has flowed out of the control chamber 10 into the low-pressure side fuel flow path 16. ) Or the flow rate change rate ΔV (point B in FIG. 4) indicating the change in the flow rate of the fuel F, or the outflow start timing ta (point C in FIG. 4) at which the outflow of the fuel F starts. After performing the control of step S30, the process proceeds to step S40.

  In step S40, based on the maximum flow rate Vmax, the flow rate change rate ΔV calculated in step S30, or the outflow start timing ta, the basic energization time Tb of the solenoid control valve 11 at the time of fuel injection from the fuel injection device 1 is determined. And the corrected energization time Td after correction is calculated. The method of correcting the basic energization time Tb and calculating the corrected energization time Td is the same as the above-described method, and thus the description thereof is omitted here. After performing the control of step S40, the process proceeds to step S50.

  In step S50, it is determined whether or not to perform fuel injection from the fuel injection device 1. When it is determined that fuel injection is not performed from the fuel injection device 1 (NO), the determination in step S50 is performed again after a preset control time has elapsed. When it is determined that fuel injection is to be performed from the fuel injection device 1 (YES), the process proceeds to step S60, and in step S60, the solenoid control valve 11 is energized for the corrected energization time Td calculated in step S40. Thus, the fuel F is injected from the fuel injection device 1 to the outside. After executing the control in step S60, the process proceeds to return, and this control flow ends.

  As described above, the fuel injection control method for an internal combustion engine according to the embodiment of the present invention includes a control chamber 10 that flows in fuel from the high-pressure side fuel passage 15 and flows out from the low-pressure side fuel passage 16. A solenoid-type control valve (three-way valve) 11 that switches between a first communication state in which the control chamber 10 and the high-pressure side fuel passage 15 communicate with each other and a second communication state in which the control chamber 10 and the low-pressure side fuel passage 16 communicate with each other. The control device 40 switches the solenoid control valve (three-way valve) 11 of the fuel injection device 1 to the first communication state when the fuel is not injected, and the injection hole 17 is formed by the needle 13. This is a fuel injection control method for an internal combustion engine in which the nozzle 13 is separated from the injection hole 17 and the injection hole 17 is opened by switching to the second communication state when closing and injecting fuel.

  In this fuel injection control method for an internal combustion engine, when the solenoid control valve 11 is switched from the first communication state to the second communication state with respect to the operation state of the internal combustion engine, the needle 13 is moved from this switching time. An inspection time shorter than an injection standby time until the fuel injection is started after being separated from the injection hole 17 is set, and when the fuel injection device 1 is not injecting fuel, the solenoid control valve 11 is set to the first. After switching from the communication state to the second communication state and the inspection time has elapsed, the inspection control for returning the solenoid control valve 11 from the second communication state to the first communication state is performed. The control amount Tb of the solenoid control valve 11 at the time of fuel injection is corrected based on the correction physical amounts Vmax, ΔV, and ta obtained from the state of the fuel F flowing into the fuel flow path 16. The way.

  Further, the physical quantity obtained from the state of the fuel F at the time of the inspection control includes the maximum flow rate Vmax per unit time of the fuel, the change rate ΔV indicating the change in the flow rate V of the fuel F, and the outflow start timing ta at which the outflow of the fuel F starts. Any one or some combination of these, and at the time of fuel injection from the fuel injection device 1, a solenoid type control valve is based on any one or some combination of these physical quantities Vmax, ΔV, ta A correction time Tc related to the energization time (valve opening time) among the 11 control amounts is calculated, and the calculated correction time Tc is added to the basic energization time (basic valve opening time) Tb. The solenoid-type control valve 11 is controlled with a post-energization time (post-correction valve opening time) Td (= Tb + Tc).

  In other words, the fuel injection device 1 used in the internal combustion engine includes a control chamber 10 that flows in the fuel F from the high-pressure side fuel flow path 15 and flows out of the fuel F from the low-pressure side fuel flow path 16, and the control chamber 10 A solenoid-type control valve 11 for switching the communication state of the high-pressure side fuel flow path 15 or the low-pressure side fuel flow path 16, an elastic member 12 provided in the control chamber 10, and a needle 13 adjacent to the lower part of the control chamber 10 The fuel injection device includes a fuel storage chamber 14 that is adjacent to the lower portion of the needle 13 and the injection hole 17 and communicates with the high-pressure fuel passage 16.

  In this fuel injection device 1, the pressure of the fuel F in the control chamber 10 applied to the upper portion of the needle 13 when the control chamber 10 and the high-pressure side fuel flow path 15 are in communication with each other without energizing the solenoid control valve 11. The elastic force of the elastic member 12 and the pressure of the fuel F in the fuel storage chamber 14 applied to the lower portion of the needle 13 causes the injection hole 17 to be closed by the needle 13 and the fuel F stored in the fuel storage chamber 14. Is not ejected to the outside through the ejection holes 17.

  On the other hand, when the solenoid-type control valve 11 is energized and the control chamber 10 and the low-pressure side fuel passage 16 are in communication with each other, the fuel F flows out of the control chamber 10 into the low-pressure side fuel passage 16 and the needle 13 The pressure of the fuel F in the control chamber 10 and the elastic force of the elastic member 12 applied to the upper portion of the nozzle 13 become smaller than the pressure of the fuel F in the fuel storage chamber 14 applied to the lower portion of the needle 13, thereby separating the needle 13 from the injection hole 17. As a result, the fuel F stored in the fuel storage chamber 14 is injected outside through the injection hole 17.

  In the fuel injection control method for an internal combustion engine using this fuel injection device 1, before the time of fuel injection from the fuel injection device 1 preset according to the operating state of the internal combustion engine, the solenoid control valve 11 is Energization is performed for a preset inspection time so that the needle 13 is not separated from the injection hole 17, and inspection control for bringing the control chamber 10 and the low-pressure side fuel flow path 16 into communication is performed.

  At the same time, the maximum flow rate Vmax, which is the maximum flow rate per unit time, of the fuel F that has flowed out of the control chamber 10 into the low-pressure side fuel flow path 16 during this inspection control, or the flow rate indicating the change in the flow rate V of the fuel F. The change rate ΔV or the outflow start timing ta at which the fuel F starts to flow out is calculated, and based on the calculated maximum flow rate Vmax, the flow rate change rate ΔV or the outflow start timing ta, the fuel injection device 1 The basic energization time Tb, which is the energization time of the solenoid control valve 11 at the time of fuel injection, is corrected.

  According to the internal combustion engine and the fuel injection control method for the internal combustion engine, a solenoid type control valve (the control valve 10 between the high pressure side fuel flow path 15, the low pressure side fuel flow path 16, and the needle 13 is controlled. In the internal combustion engine provided with the combustion injection device 1 having the three-way valve 11, this is caused by the temperature of the wall surface in the vicinity of the orifice 16 a that passes when flowing out from the control chamber 10 of the fuel injection device 1 to the low pressure side fuel flow path 16. Variations in the fuel injection amount from the fuel injection device 1 can be corrected, and as a result, fuel injection control can be performed with high accuracy.

DESCRIPTION OF SYMBOLS 1 Fuel injection device 10 of internal combustion engine Control chamber 11 Solenoid control valve 11a Solenoid 12 Energizing spring (elastic member)
13 Needle 14 Fuel storage chamber 15 High pressure side fuel flow path 16 Low pressure side fuel flow path 16a Orifice 17 Injection hole 20 Flow meter 40 Control device F Fuel ta Outflow start timing Tb Basic energization time (basic valve opening time)
Tc correction time Td correction energization time (post-correction valve opening time)
Vmax Maximum flow rate ΔV Flow rate change rate

Claims (4)

A control chamber in which fuel flows in from the high pressure side fuel flow path and fuel flows out from the low pressure side fuel flow path, a first communication state in which the control chamber and the high pressure side fuel flow path communicate with each other, the control chamber and the low pressure A fuel injection device having a three-way valve that switches between the second communication state in which the side fuel flow path communicates, and the control device switches the three-way valve of the fuel injection device to the first communication state when fuel is not injected. In an internal combustion engine that closes an injection hole with a needle and switches to a second communication state when injecting fuel, separates the needle from the injection hole and opens the injection hole.
The control device is
When the three-way valve is switched from the first communication state to the second communication state with respect to the operating state of the internal combustion engine, from this switching time until the needle is separated from the injection hole until fuel injection is started. Set an inspection time shorter than the injection standby time,
When the fuel injection device is not injecting fuel, the three-way valve is switched from the first communication state to the second communication state, and after the inspection time has elapsed, the three-way valve is moved from the second communication state to the first communication state. In addition to performing the inspection control to return to the communication state, the control amount of the three-way valve at the time of fuel injection is determined based on the physical quantity for correction obtained from the state of the fuel that has flowed into the low-pressure side fuel flow path during the inspection control. An internal combustion engine configured to perform correction control. The control device is
The physical quantity obtained from the state of the fuel at the time of the inspection control is any one or some combination of the maximum flow rate per unit time of the fuel, the rate of change of the flow rate of the fuel, or the timing at which the outflow of fuel starts. ,
At the time of fuel injection from the fuel injection device, based on these physical quantities, a correction time related to the valve opening time of the control amount of the three-way valve is calculated, and the calculated correction time is used as the basic valve opening time. 2. The internal combustion engine according to claim 1, wherein the three-way valve is controlled with a corrected valve opening time calculated by adding to the valve. A control chamber in which fuel flows in from the high pressure side fuel flow path and fuel flows out from the low pressure side fuel flow path, a first communication state in which the control chamber and the high pressure side fuel flow path communicate with each other, the control chamber and the low pressure A fuel injection device having a three-way valve that switches between the second communication state in which the side fuel flow path communicates, and the control device switches the three-way valve of the fuel injection device to the first communication state when fuel is not injected. In a fuel injection control method for an internal combustion engine that closes an injection hole with a needle and switches to a second communication state when fuel is injected and separates the needle from the injection hole to open the injection hole.
When the three-way valve is switched from the first communication state to the second communication state with respect to the operating state of the internal combustion engine, from this switching time until the needle is separated from the injection hole until fuel injection is started. Set an inspection time shorter than the injection standby time,
When the fuel injection device is not injecting fuel, the three-way valve is switched from the first communication state to the second communication state, and after the inspection time has elapsed, the three-way valve is moved from the second communication state to the first communication state. In addition to performing the inspection control to return to the communication state, the control amount of the three-way valve at the time of fuel injection is determined based on the physical quantity for correction obtained from the state of the fuel that has flowed into the low-pressure side fuel flow path during the inspection control. A fuel injection control method for an internal combustion engine, wherein the correction is performed. The physical quantity obtained from the state of the fuel at the time of the inspection control is any one or some combination of the maximum flow rate per unit time of the fuel, the rate of change of the flow rate of the fuel, or the timing at which the outflow of fuel starts. ,
At the time of fuel injection from the fuel injection device, based on these physical quantities, a correction time related to the valve opening time of the control amount of the three-way valve is calculated, and the calculated correction time is used as the basic valve opening time. The fuel injection control method for an internal combustion engine according to claim 3, wherein the three-way valve is controlled with a post-correction valve opening time calculated by adding to the value.

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