JP2006257968A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately inject a minute amount of fuel corresponding to a required injection time shorter than a peak current application time, as requested. <P>SOLUTION: A fuel injection control device 2 has an injector 6 for high-pressure fuel and an electronic control unit (ECU) 20. A final injection time is calculated based on the required injection time depending on engine operational status, and an invalid injection time for correcting the required injection time. The ECU 20 makes the injector 6 open by energization according to the final injection time and makes the injector 6 inject fuel to the engine 1, the ECU applies a predetermined peak current to quickly open the injector 6 in the start of the energization, and then controls the injector 6 by applying a holding current smaller than the peak current to hold the valve open state. When the requested injection time is shorter than the peak current application time, the ECU 20 corrects the invalid injection time depending on difference in required injection time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection control device for an internal combustion engine that controls the amount of fuel injected from a fuel injection valve for high pressure fuel to the internal combustion engine.

  Conventionally, as this type of device, for example, there is a fuel injection device for a cylinder injection engine described in Patent Document 1 below. This apparatus relates to an in-cylinder injection engine that directly injects fuel into an engine combustion chamber. In order to inject fuel directly from a fuel injection valve (injector) into the combustion chamber during the compression stroke of the engine, High pressure fuel is supplied. In this type of high pressure fuel type injector, a strong spring is provided to press the valve body against the valve seat against the high pressure fuel when the valve is closed. For this reason, when the valve is opened, it is necessary to move the valve body against a strong spring, and a high voltage must be applied to the solenoid coil. Therefore, in the device described in Patent Document 1, when energization of the injector is started, a predetermined large current (peak current) is energized to move the valve body against a strong spring to quickly open the injector. After that, the valve opening state of the injector is held by energizing the injector with a valve opening holding current (hold current) smaller than the peak current.

Japanese Patent Laid-Open No. 10-266885 (5th and 6th pages, FIG. 5)

  However, in the apparatus described in Patent Document 1 described above, a predetermined peak current is applied to quickly open the injector when energization of the injector is started. Therefore, if the required injection time calculated according to the operating state of the engine (the time during which the injector is energized to inject the required amount of fuel) is shorter than the energization time of the peak current, the required injection time It was difficult to open the injector on time, and the fuel actually injected from the injector tended to be larger than the required injection amount. This is because the fall of the peak current tends to be delayed from the fall of the hold current. Therefore, a very small amount of fuel cannot be injected accurately from the injector as required. For this reason, in the relationship between the energization time for the injector and the injection amount from the injector, it is not possible to ensure a characteristic with linearity and to control the air-fuel ratio of the engine with high accuracy.

  The present invention has been made in view of the above circumstances, and its object is to inject a small amount of fuel corresponding to the required injection time or the final injection time that is shorter than the energization time of the peak current with high accuracy as required. An object of the present invention is to provide a fuel injection control device for an internal combustion engine that can be used.

  In order to achieve the above object, the invention according to claim 1 calculates a fuel injection valve for high-pressure fuel that injects fuel by opening the valve by energization, and a required injection time according to the operating state of the internal combustion engine. Required injection time calculation means for correcting, correction time calculation means for calculating a correction time for correcting the required injection time, and final injection time calculation for calculating a final injection time based on the required injection time and the correction time Means for opening the fuel injection valve by injecting current according to the final injection time to inject the fuel into the internal combustion engine, and at the start of the energization, the fuel injection valve is quickly opened at a predetermined peak. In a fuel injection control device for an internal combustion engine that controls the fuel injection amount by supplying a current and then supplying a hold current smaller than the peak current in order to maintain the valve open state, at the time of required injection When is shorter than the energization time of the peak current, and the spirit that a correction time correction means for correcting the correction time according to a difference in the required injection time.

  According to the configuration of the invention, when the internal combustion engine is operated, the final injection time is calculated based on the required injection time calculated according to the operating state and the calculated correction time. The fuel injection valve for high-pressure fuel is energized according to the final injection time, so that the fuel injection valve is opened and fuel is injected into the internal combustion engine. At this time, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter a hold current smaller than the peak current is energized to maintain the valve open state. Thereby, the fuel injection amount from the fuel injection valve is controlled. Here, when the required injection time becomes shorter than the energization time of the peak current, the correction time is corrected according to the difference in the required injection time, and the final injection time is corrected. Therefore, when the required injection time is shorter than the energization time of the peak current, it is possible to calculate the final injection time in accordance with the falling delay of the peak current.

  In order to achieve the above object, the invention according to claim 2 calculates a fuel injection valve for high-pressure fuel that injects fuel by opening the valve by energization, and a required injection time according to the operating state of the internal combustion engine. Required injection time calculation means for correcting, correction time calculation means for calculating a correction time for correcting the required injection time, and final injection time calculation for calculating a final injection time based on the required injection time and the correction time Means for opening the fuel injection valve by injecting current according to the final injection time to inject the fuel into the internal combustion engine, and at the start of the energization, the fuel injection valve is quickly opened at a predetermined peak. In the fuel injection control device for an internal combustion engine that controls the fuel injection amount by supplying a current and then supplying a hold current smaller than the peak current in order to maintain the valve open state. When it is shorter than the energization time of the peak current, and the spirit further comprising a final injection time correction means for correcting the final injection time according to a difference in the required injection time or final injection time.

  According to the configuration of the invention, when the internal combustion engine is operated, the final injection time is calculated based on the required injection time calculated according to the operating state and the calculated correction time. The fuel injection valve for high-pressure fuel is energized according to the final injection time, so that the fuel injection valve is opened and fuel is injected into the internal combustion engine. At this time, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter a hold current smaller than the peak current is energized to maintain the valve open state. Thereby, the fuel injection amount from the fuel injection valve is controlled. Here, when the final injection time is shorter than the energization time of the peak current, the final injection time is corrected according to the difference in the required injection time or the final injection time. Therefore, when the final injection time is shorter than the energization time of the peak current, it is possible to calculate the final injection time in accordance with the falling delay of the peak current.

  In order to achieve the above object, the invention according to claim 3 calculates a fuel injection valve for high-pressure fuel that injects fuel by opening the valve by energization, and a required injection time according to the operating state of the internal combustion engine. Required injection time calculation means for correcting, correction time calculation means for calculating a correction time for correcting the required injection time, and final injection time calculation for calculating a final injection time based on the required injection time and the correction time Means for opening the fuel injection valve by injecting current according to the final injection time to inject the fuel into the internal combustion engine, and at the start of the energization, the fuel injection valve is quickly opened at a predetermined peak. In a fuel injection control device for an internal combustion engine that controls the fuel injection amount by supplying a current and then supplying a hold current smaller than the peak current to maintain the valve open state, the peak current A time difference between the response delay time of the fuel injection valve at the time of power supply and the response delay time of the fuel injection valve at the time of energization of the hold current is calculated in advance, and when the required injection time is shorter than the current supply time of the peak current, the correction time It is intended that a correction time correction means for correcting the time difference by a time difference is provided.

  According to the configuration of the invention, when the internal combustion engine is operated, the final injection time is calculated based on the required injection time calculated according to the operating state and the calculated correction time. The fuel injection valve for high-pressure fuel is energized according to the final injection time, so that the fuel injection valve is opened and fuel is injected into the internal combustion engine. At this time, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter a hold current smaller than the peak current is energized to maintain the valve open state. Thereby, the fuel injection amount from the fuel injection valve is controlled. Here, when the required injection time is shorter than the energization time of the peak current, the response delay time of the fuel injection valve when energizing the peak current and the response delay time of the fuel injection valve when energizing the hold current are calculated in advance. The correction time is corrected by this time difference, and the final injection time is corrected. Therefore, when the required injection time is shorter than the energization time of the peak current, it is possible to calculate the final injection time in accordance with the falling delay of the peak current.

  In order to achieve the above object, the invention described in claim 4 calculates a fuel injection valve for high pressure fuel that injects fuel by opening the valve by energization, and a required injection time according to the operating state of the internal combustion engine. Required injection time calculation means for correcting, correction time calculation means for calculating a correction time for correcting the required injection time, and final injection time calculation for calculating a final injection time based on the required injection time and the correction time Means for opening the fuel injection valve by injecting current according to the final injection time to inject the fuel into the internal combustion engine, and at the start of the energization, the fuel injection valve is quickly opened at a predetermined peak. In a fuel injection control device for an internal combustion engine that controls the fuel injection amount by supplying a current and then supplying a hold current smaller than the peak current to maintain the valve open state, the peak current When the time difference between the response delay time of the fuel injection valve at the time of electricity and the response delay time of the fuel injection valve at the time of energization of the hold current is calculated in advance, and the final injection time is shorter than the energization time of the peak current, the final injection time The purpose is to provide a final injection time correction means for correcting the above by a time difference.

  According to the configuration of the invention, when the internal combustion engine is operated, the final injection time is calculated based on the required injection time calculated according to the operating state and the calculated correction time. The fuel injection valve for high-pressure fuel is energized according to the final injection time, so that the fuel injection valve is opened and fuel is injected into the internal combustion engine. At this time, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter a hold current smaller than the peak current is energized to maintain the valve open state. Thereby, the fuel injection amount from the fuel injection valve is controlled. Here, when the final injection time is shorter than the energization time of the peak current, the response delay time of the fuel injection valve when energizing the peak current and the response delay time of the fuel injection valve when energizing the hold current are calculated in advance. The final injection time is corrected by this time difference. Therefore, when the final injection time is shorter than the energization time of the peak current, it is possible to calculate the final injection time in accordance with the falling delay of the peak current.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the correction time calculation means includes: a fuel pressure supplied to the fuel injection valve; The purpose is to calculate the correction time based on the pressure difference from the intake pressure and the power supply voltage for energization.

  In general, it is known that the operation delay of the fuel injection valve affects the control of the fuel injection amount. It is known that this operation delay is affected by the pressure difference between the fuel pressure supplied to the fuel injection valve and the intake pressure and the power supply voltage for energizing the fuel injection valve. According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 1 to 4, the correction time for correcting the required injection time includes the pressure difference between the fuel pressure and the intake pressure, and the power supply voltage. Since it is calculated based on this, it becomes possible to cope with the operation delay of the fuel injection valve.

  According to the first aspect of the present invention, even when a small amount of fuel corresponding to the injection time such that the required injection time is shorter than the energization time of the peak current is injected from the fuel injection valve, the accuracy is exactly as required. Fuel can be injected. As a result, a characteristic having linearity can be ensured with respect to the relationship between the energization time for the fuel injection valve and the fuel injection amount from the fuel injection valve, and the air-fuel ratio of the internal combustion engine can be controlled with high accuracy.

  According to the second aspect of the present invention, even when a small amount of fuel corresponding to the injection time such that the final injection time is shorter than the energization time of the peak current is injected from the fuel injection valve, the accuracy is exactly as required. Fuel can be injected. As a result, a characteristic having linearity can be ensured with respect to the relationship between the energization time for the fuel injection valve and the fuel injection amount from the fuel injection valve, and the air-fuel ratio of the internal combustion engine can be controlled with high accuracy.

  According to the third aspect of the present invention, even when a small amount of fuel corresponding to the injection time such that the required injection time is shorter than the energization time of the peak current is injected from the fuel injection valve, the accuracy is exactly as required. Fuel can be injected. As a result, a characteristic having linearity can be ensured with respect to the relationship between the energization time for the fuel injection valve and the fuel injection amount from the fuel injection valve, and the air-fuel ratio of the internal combustion engine can be controlled with high accuracy.

  According to the fourth aspect of the present invention, even when a small amount of fuel corresponding to the injection time such that the final injection time is shorter than the energization time of the peak current is injected from the fuel injection valve, the accuracy is exactly as required. Fuel can be injected. As a result, a characteristic having linearity can be ensured with respect to the relationship between the energization time for the fuel injection valve and the fuel injection amount from the fuel injection valve, and the air-fuel ratio of the internal combustion engine can be controlled with high accuracy.

  According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, an error in the fuel injection amount from the fuel injection valve can be reduced.

[First Embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment in which a fuel injection control device for an internal combustion engine according to the present invention is embodied will be described in detail with reference to the drawings. In this embodiment, the fuel injection control device will be specifically described as an LPG engine using liquefied petroleum gas (LPG) as liquefied gas fuel.

  FIG. 1 is a schematic configuration diagram showing a fuel injection control device of this embodiment. An LPG engine system mounted on a vehicle includes an LPG engine 1 and a fuel injection control device 2 that injects and supplies LPG as fuel to the engine 1. The fuel injection control device 2 includes a fuel tank 3 that stores LPG in a liquid phase state. The fuel pump 4 built in the fuel tank 3 sucks the liquid phase LPG stored in the tank 3 and discharges it to the fuel passage 5 at a high pressure. The fuel passage 5 extends to the LPG engine 1. In this embodiment, the fuel pump 4 is of a type that sucks fuel by rotating the impeller by a motor and discharges the fuel to the fuel passage 5 at a high pressure. In this embodiment, the fuel tank 3 includes a main tank 3b and a sub tank 3c that are partitioned by a partition wall 3a. The fuel pump 4 is disposed and provided in the sub tank 3c.

  In this embodiment, the LPG engine 1 is of a four-cylinder reciprocating type, and an injector 6 is provided as a fuel injection valve for high pressure fuel that injects and supplies liquid phase LPG corresponding to each cylinder. . Each injector 6 is provided in a delivery pipe 7.

  Each injector 6 includes a valve body for injecting and stopping the fuel, a valve seat corresponding to the valve body, a powerful spring for pressing the valve body against the valve seat, and the valve body as a biasing force of the spring. And a coil that attracts and resists. Then, when the coil of the injector 6 is energized by energization, the valve body is attracted to the coil against a strong spring, and the valve body opens away from the valve seat. Thereafter, the coil is demagnetized by stopping energization, and the valve body is pressed against the valve seat by the spring to close the valve. FIG. 2 is a time chart showing the behavior of energization performed on the coils of each injector 6 during one fuel injection. In this embodiment, when energization of the injector 6 is started, a predetermined peak current is energized in order to quickly open the injector 6, thereby moving the valve body against a strong spring to quickly move the injector. The fuel injection amount from the injector 6 is adjusted by opening the valve and then energizing a hold current smaller than the peak current in order to maintain the valve open state.

  Here, the liquid phase LPG discharged from the fuel pump 4 is supplied by being pumped to the injectors 6 through the fuel passage 5 and the delivery pipe 7. The supplied LPG in the liquid phase state is injected in a liquid phase state into each intake port of the LPG engine 1 by the operation of each injector 6. The liquid phase LPG injected from each injector 6 forms a combustible air-fuel mixture with air taken from an intake passage (not shown) and is sucked into each cylinder. The liquid phase LPG remaining in the delivery pipe 7 is returned to the fuel tank 3 through the return passage 8 as return fuel.

  In this embodiment, the return passage 8 has a tip portion disposed in the sub tank 3c, and returns the return fuel to the sub tank 3c. A pressure regulator 9 for keeping the fuel pressure constant is provided at the tip of the return passage 8. The delivery pipe 7 is provided with a fuel pressure sensor 10 for detecting the fuel pressure (delivery fuel pressure) Pdf therein.

  In this embodiment, an electronic control unit (ECU) 20 is provided to control each injector 6 and the fuel pump 4. The ECU 20 corresponds to the required injection time calculation means, correction time calculation means, final injection time calculation means, and correction time correction means of the present invention. The ECU 20 is connected to the fuel pump 4 and each injector 6. The ECU 20 is connected to a fuel pressure sensor 10 and a power source (battery) 11 for energization. Further, the ECU 20 is connected with various sensors for detecting various operation parameters indicating the operation state of the LPG engine 1. With these sensors, the ECU 20 causes the intake pressure PM in the intake manifold of the LPG engine 1, the rotational speed (engine rotational speed) NE of the LPG engine 1, the coolant temperature THW of the engine body, and the exhaust gas discharged from the LPG engine 1. The oxygen concentration Ox in the gas is input as various operation parameters. In addition, the ECU 20 measures the voltage (battery voltage) VB of the battery 11. Then, the ECU 20 executes fuel injection control based on various operating parameters, that is, the intake pressure PM, the engine rotational speed NE, the coolant temperature THW and the oxygen concentration Ox, and the detected values of the delivery fuel pressure Pdf and the battery voltage VB. Therefore, the injectors 6 and the fuel pump 4 are controlled.

  The ECU 20 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 20 constitutes a logical operation circuit formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like through a bus. Each ROM stores a predetermined control program related to various controls in advance. Each RAM temporarily stores the calculation result of each CPU. Each backup RAM stores data stored in advance. Each CPU executes various controls according to a predetermined control program based on signals from the various sensors 10, 11 and the like input via the input circuit.

  Next, the fuel injection control program executed by the ECU 20 will be described with reference to the flowchart of FIG.

  First, in step 100, the ECU 20 reads detection values relating to various operation parameters of the LPG engine 1. That is, the ECU 20 reads the detected values of the intake pressure PM, the engine rotation speed NE, the coolant temperature THW, and the oxygen concentration Ox from various sensors.

  Next, in step 110, the ECU 20 calculates a required injection time TAU for each injector 6 based on the read various operation parameters. That is, the ECU 20 calculates a basic injection time per time based on the intake pressure PM and the engine rotational speed NE, and converts the basic injection time to the cooling water temperature THW and the air-fuel ratio obtained from the oxygen concentration Ox. Based on this correction, the required injection time TAU corresponding to the operating state of the LPG engine 1 is calculated.

  Subsequently, in step 120, the ECU 20 reads the delivery fuel pressure Pdf from the fuel pressure sensor 10 and the battery voltage VB related to the battery 11, respectively.

  Next, at step 130, the ECU 20 calculates a difference between the delivery fuel pressure Pdf and the intake pressure PM as a pressure difference ΔPfi. This pressure difference ΔPfi means a substantial fuel pressure applied to the valve body of each injector 6.

  In step 140, the ECU 20 determines whether or not the calculated required injection time TAU is shorter than a predetermined value T1. The predetermined value T1 is, for example, a value corresponding to the energization time of the peak current shown in FIG. 2 (period from time t0 to t1 shown in FIG. 2), and for example, “2 ms” can be applied.

  If the determination result in step 140 is affirmative, that is, if the required injection time TAU is shorter than the predetermined value T1, the ECU 20 determines in step 150 based on the pressure difference ΔPfi, the battery voltage VB, and the required injection time TAU. The invalid injection time TAUV as the correction time of the present invention is calculated. In this embodiment, the ECU 20 calculates the invalid injection time TAUV with reference to a map as shown in FIG. This map is composed of a plurality of basic maps having different setting contents depending on the difference in the required injection time TAU. In each basic map, the invalid injection time TAUV is set based on the pressure difference ΔPfi and the battery voltage VB. Each basic map is set such that the invalid injection time TAUV decreases as the pressure difference ΔPfi increases, and the invalid injection time TAUV decreases as the battery voltage VB increases. Further, the invalid injection time TAUV of each basic map is set to become relatively longer as the required injection time TAU becomes longer.

  On the other hand, if the determination result in step 140 is negative, that is, if the required injection time TAU is equal to or greater than the predetermined value T1, the ECU 20 determines in step 160 the correction time of the present invention based on the pressure difference ΔPfi and the battery voltage VB. The invalid injection time TAUV is calculated. In this embodiment, the ECU 20 calculates the invalid injection time TAUV with reference to a map as shown in FIG. In this map, the invalid injection time TAUV is set based only on the pressure difference ΔPfi and the battery voltage VB. That is, in this map, the invalid injection time TAUV is set to become shorter as the pressure difference ΔPfi becomes larger, and the invalid injection time TAUV becomes shorter as the battery voltage VB becomes larger.

  In step 170 after shifting from step 150 or step 160, the ECU 20 calculates the final injection time TAUIF per time by adding the invalid injection time TAUV to the required injection time TAU.

  In step 180, the ECU 20 controls energization of the injector 6 based on the calculated final injection time TAUIF. That is, the ECU 20 energizes the injector 6 once per an energization pattern as shown in FIG. 2 or an energization pattern of only a peak current.

  As described above, according to the fuel injection control device 2 of this embodiment, when the LPG engine 1 is operated, based on the required injection time TAU calculated according to the operating state and the calculated invalid injection time TAUV. Thus, the final injection time TAUIF is calculated. Then, each injector 6 for high-pressure fuel is energized according to the final injection time TAUIF, whereby each injector 6 is opened and fuel is injected into the LPG engine 1. At this time, as shown in FIG. 2, at the start of energization (time t0 to t1), a predetermined peak current is energized to the injector 6 in order to quickly open the injector 6, and thereafter (time t1 to t2). In order to hold the valve open state, a hold current smaller than the peak current is supplied to the injector 6. Thereby, the fuel injection amount from the injector 6 is controlled.

  Here, in this embodiment, when the calculated required injection time TAU is shorter than the predetermined value T1 (the energization time of the peak current), the invalid injection time TAUV is corrected according to the difference in the required injection time TAU, As a result, the final injection time TAUIF is corrected. That is, when the required injection time TAU becomes shorter than the energization time of the peak current, the invalid injection is performed based on the required injection time TAU in addition to the pressure difference ΔPfi and the battery voltage VB with reference to the map as shown in FIG. By calculating the time TAUV, the invalid injection time TAUV is corrected according to the difference in the required injection time TAU. Therefore, when the required injection time TAU is shorter than the energization time of the peak current, the final injection time TAUIF can be calculated in accordance with the falling delay of the peak current. Therefore, even when a small amount of fuel corresponding to the required injection time TAU that is shorter than the energization time of the peak current is injected from the injector 6, the fuel can be injected with high accuracy as required. As a result, a characteristic with linearity can be secured with respect to the relationship between the energization time to the injector 6 and the fuel injection amount from the injector 6, and the air-fuel ratio of the LPG engine 1 can be controlled with high accuracy. It becomes like this.

  Here, it is generally known that the operation delay of an injector affects the control of the fuel injection amount from the injector. It is known that this operation delay is affected by the pressure difference between the fuel pressure supplied to the injector and the intake pressure, and the battery voltage for energizing the injector. In this embodiment, the invalid injection time TAUV for correcting the required injection time TAU is calculated based on the pressure difference ΔPfi between the delivery fuel pressure Pdf and the intake pressure PM, the battery voltage VB, and the required injection time TAU. It becomes possible to cope with the operation delay of 6. For this reason, the error of the fuel injection amount from each injector 6 can be reduced.

[Second Embodiment]
Next, a second embodiment of the fuel injection control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In the following embodiments including this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and differences will be mainly described.

  This embodiment differs from the first embodiment in the content of the fuel injection control program. FIG. 6 is a flowchart showing the contents of the program. In this embodiment, the ECU 20 corresponds to the required injection time calculation means, correction time calculation means, final injection time calculation means, and final injection time correction means of the present invention.

  In this embodiment, the contents of step 100 to step 130 are the same as those of FIG. 3 described in the first embodiment.

  Shifting from step 130, in step 200, the ECU 20 calculates the invalid injection time TAUV as the correction time of the present invention based on the pressure difference ΔPfi and the battery voltage VB. In this embodiment, the ECU 20 calculates the invalid injection time TAUV with reference to the map shown in FIG.

  Next, in step 210, the ECU 20 calculates the final injection time TAUIF per time by adding the invalid injection time TAUV to the required injection time TAU.

  In step 220, the ECU 20 determines whether or not the calculated final injection time TAUIF is shorter than a predetermined value T1. The predetermined value T1 is, for example, a value corresponding to the energization time of the peak current shown in FIG. 2 (period from time t0 to t1 shown in FIG. 2), and for example, “2 ms” can be applied.

  If the determination result in step 220 is affirmative, that is, if the final injection time TAUIF is shorter than the predetermined value T1, the ECU 20 determines in step 230 as the correction time of the present invention based on the final injection time TAUIF. A final injection time correction value CIF is calculated. In this embodiment, the ECU 20 calculates the final injection time correction value CIF with reference to a predetermined map. For example, in this map, the final injection time correction value CIF is set to become relatively longer as the final injection time TAUIF becomes longer.

  On the other hand, if the determination result in step 220 is negative, that is, if the final injection time TAUIF is equal to or greater than the predetermined value T1, the ECU 20 sets the final injection time correction value CIF to “0” in step 240.

  In step 250 after shifting from step 230 or step 240, the ECU 20 corrects the final injection time TAUIF per time by subtracting the final injection time correction value CIF from the final injection time TAUIF.

  In step 260, the ECU 20 controls energization of the injector 6 based on the corrected final injection time TAUIF.

  Therefore, according to the fuel injection control device 2 of this embodiment, unlike the first embodiment, when the final injection time TAUIF is shorter than a predetermined value T1 (peak current conduction time), the final injection time TAUIF The final injection time TAUIF is corrected by the final injection time correction value CIF calculated according to the difference. Therefore, when the final injection time TAUIF becomes shorter than the energization time of the peak current, it becomes possible to obtain the final injection time TAUIF in accordance with the falling delay of the peak current. Therefore, even when a small amount of fuel corresponding to the final injection time TAUIF that is shorter than the energization time of the peak current is injected from the injector 6, the fuel can be injected with high accuracy as required. As a result, a characteristic with linearity can be secured with respect to the relationship between the energization time to the injector 6 and the fuel injection amount from the injector 6, and the air-fuel ratio of the LPG engine 1 can be controlled with high accuracy. It becomes like this.

[Third Embodiment]
Next, a third embodiment that embodies the fuel injection control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the above embodiments in terms of the contents of the fuel injection control program. FIG. 7 is a flowchart showing the contents of the program. In this embodiment, the ECU 20 corresponds to the required injection time calculation means, correction time calculation means, final injection time calculation means, and correction time correction means of the present invention.

  In this embodiment, the contents of Step 100 to Step 130 and Step 200 are the same as those in FIG. 6 described in the second embodiment.

  Transitioning from step 200, in step 300, the ECU 20 determines whether or not the calculated required injection time TAU is shorter than a predetermined value T1. The predetermined value T1 is, for example, a value corresponding to the energization time of the peak current shown in FIG. 2 (period from time t0 to t1 shown in FIG. 2), and for example, “2 ms” can be applied.

  If the determination result in step 300 is affirmative, that is, if the required injection time TAU is shorter than the predetermined value T1, the ECU 20 corrects the calculated invalid injection time TAUV in step 310. In other words, in this embodiment, the difference (delay time difference) between the peak current delay time Tc2 and the hold current delay time Tc1 is calculated in advance, and the invalid injection time is subtracted from the calculated invalid injection time TAUV. Correct the time TAUV. FIG. 8 shows the behavior of “energization current”, “energization” to the injector 6 and actual “drive” of the injector 6 when the required injection time TAU is longer than the energization time of the peak current. FIG. 9 shows the behavior of “energization current”, “energization” to the injector 6 and actual “drive” of the injector 6 when the required injection time TAU is shorter than the energization time of the peak current. 8 and 9, it can be seen that the actual “drive” timing of the injector 6 is delayed with respect to the “energization” timing for the injector 6. Here, as shown in FIG. 8, the difference between the “energization” off timing (time t2) and the “drive” closing timing (time t3) at the fall of the hold current is defined as “hold current delay time Tc1”. To do. Also, as shown in FIG. 9, the difference between the “energization” off timing (time t2) and the “driving” closing timing (time t3) at the fall of the peak current is defined as “peak current delay time Tc2”. .

  On the other hand, if the determination result in step 300 is negative, that is, if the required injection time TAU is equal to or greater than the predetermined value T1, the ECU 20 proceeds to step 320 as it is.

  In step 320 after shifting from step 310 or step 300, the ECU 20 calculates the final injection time TAUIF per time by adding the corrected invalid injection time TAUV to the required injection time TAU.

  In step 330, the ECU 20 controls energization of the injector 6 based on the calculated final injection time TAUIF.

  Therefore, according to the fuel injection control device 2 of this embodiment, unlike the above-described embodiments, when the required injection time TAU is shorter than the predetermined value T1 (peak current application time), a delay that has been calculated in advance. The final injection time TAUIF is corrected by correcting the invalid injection time TAUV by the time difference (Tc2−Tc1). Therefore, when the required injection time TAU is shorter than the energization time of the peak current, the final injection time TAUIF can be calculated in accordance with the falling delay of the peak current. Therefore, even when a small amount of fuel corresponding to the final injection time TAUIF that is shorter than the energization time of the peak current is injected from the injector 6, the fuel can be injected with high accuracy as required. As a result, a characteristic with linearity can be secured with respect to the relationship between the energization time to the injector 6 and the fuel injection amount from the injector 6, and the air-fuel ratio of the LPG engine 1 can be controlled with high accuracy. It becomes like this.

[Fourth Embodiment]
Next, a fourth embodiment embodying a fuel injection control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the above embodiments in terms of the contents of the fuel injection control program. FIG. 10 is a flowchart showing the contents of the program. In this embodiment, the ECU 20 corresponds to the required injection time calculation means, correction time calculation means, final injection time calculation means, and final injection time correction means of the present invention.

  In this embodiment, the contents of Step 100 to Step 130 and Step 200 are the same as those in FIG. 6 described in the second embodiment.

  After step 200, the ECU 20 calculates the final injection time TAUIF per time by adding the invalid injection time TAUV to the required injection time TAU in step 400.

  Next, in step 410, the ECU 20 determines whether or not the calculated final injection time TAUIF is shorter than a predetermined value T1. The predetermined value T1 is, for example, a value corresponding to the energization time of the peak current shown in FIG. 2 (period from time t0 to t1 shown in FIG. 2), and for example, “2 ms” can be applied.

  If the determination result in step 410 is affirmative, that is, if the final injection time TAUIF is shorter than the predetermined value T1, the ECU 20 corrects the calculated final injection time TAUIF in step 420. In other words, in this embodiment, a difference (delay time difference) between the peak current delay time Tc2 and the hold current delay time Tc1 is calculated in advance, and the final injection time is subtracted from the calculated final injection time TAUIF. Correct the time TAUIF.

  On the other hand, if the determination result in step 410 is negative, that is, if the final injection time TAUIF is equal to or greater than the predetermined value T1, the ECU 20 proceeds to step 430 as it is.

  After step 420 or step 410, in step 430, the ECU 20 controls the energization of the injector 6 based on the corrected final injection time TAUIF.

  Therefore, according to the fuel injection control device 2 of this embodiment, unlike the above-described embodiments, when the final injection time TAUIF is shorter than the predetermined value T1 (energization time of peak current), a delay calculated in advance. The final injection time TAUIF is corrected by the time difference (Tc2−Tc1). Therefore, when the final injection time TAUIF becomes shorter than the energization time of the peak current, it becomes possible to calculate the final injection time TAUIF in accordance with the falling delay of the peak current. Therefore, even when a small amount of fuel corresponding to the final injection time TAUIF that is shorter than the energization time of the peak current is injected from the injector 6, the fuel can be injected with high accuracy as required. As a result, a characteristic with linearity can be secured with respect to the relationship between the energization time to the injector 6 and the fuel injection amount from the injector 6, and the air-fuel ratio of the LPG engine 1 can be controlled with high accuracy. It becomes like this.

  The present invention is not limited to the above-described embodiments, and can be carried out as follows without departing from the spirit of the invention.

  (1) In the second embodiment, in step 230, the final injection time correction value CIF is calculated based on the final injection time TAUIF. However, the correction value CIF is calculated based on the required injection time TAUIF. May be.

  (2) In each of the above embodiments, the present invention is embodied in the fuel injection control device 2 that uses LPG as fuel. However, the present invention is not limited to LPG, and a fuel injection control device that uses LNG, dimethyl ether, or hydrogen gas, and It can also be embodied in a fuel injection control device for an in-cylinder direct injection engine using gasoline as fuel.

The schematic block diagram which shows a fuel-injection control apparatus. The time chart which shows the behavior of the electricity supply with respect to an injector. The flowchart which shows the program of fuel-injection control. Map for calculating invalid injection time. Map for calculating invalid injection time. The flowchart which shows the program of fuel-injection control. The flowchart which shows the program of fuel-injection control. The time chart which shows the behavior of the energization current with respect to an injector, energization, and a drive. The time chart which shows the behavior of the energization current with respect to an injector, energization, and a drive. The flowchart which shows the program of fuel-injection control.

Explanation of symbols

1 LPG engine 2 Fuel injection control device 6 Injector (fuel injection valve)
11 Battery (Power)
20 ECU (required injection time calculation means, correction time calculation means, final injection time calculation means, correction time correction means, final injection time correction means)

Claims (5)

A fuel injection valve for high pressure fuel that injects fuel by opening the valve when energized;
A required injection time calculating means for calculating a required injection time according to the operating state of the internal combustion engine;
Correction time calculation means for calculating a correction time for correcting the required injection time;
A final injection time calculating means for calculating a final injection time based on the required injection time and the correction time, and energizing the fuel injection valve in response to the final injection time to open the fuel injection valve. While injecting fuel into the engine, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter, a hold smaller than the peak current is held to maintain the valve open state. In a fuel injection control device for an internal combustion engine that controls a fuel injection amount by energizing a current,
A fuel injection control device for an internal combustion engine, comprising: correction time correction means for correcting the correction time according to the difference in the required injection time when the required injection time is shorter than the energization time of the peak current. . A fuel injection valve for high pressure fuel that injects fuel by opening the valve when energized;
A required injection time calculating means for calculating a required injection time according to the operating state of the internal combustion engine;
Correction time calculation means for calculating a correction time for correcting the required injection time;
A final injection time calculating means for calculating a final injection time based on the required injection time and the correction time, and energizing the fuel injection valve in response to the final injection time to open the fuel injection valve. While injecting fuel into the engine, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter, a hold smaller than the peak current is held to maintain the valve open state. In a fuel injection control device for an internal combustion engine that controls a fuel injection amount by energizing a current,
When the final injection time becomes shorter than the energization time of the peak current, it is provided with final injection time correction means for correcting the final injection time according to the difference in the required injection time or the final injection time. A fuel injection control device for an internal combustion engine. A fuel injection valve for high pressure fuel that injects fuel by opening the valve when energized;
A required injection time calculating means for calculating a required injection time according to the operating state of the internal combustion engine;
Correction time calculation means for calculating a correction time for correcting the required injection time;
A final injection time calculating means for calculating a final injection time based on the required injection time and the correction time, and energizing the fuel injection valve in response to the final injection time to open the fuel injection valve. While injecting fuel into the engine, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter, a hold smaller than the peak current is held to maintain the valve open state. In a fuel injection control device for an internal combustion engine that controls a fuel injection amount by energizing a current,
A time difference between the response delay time of the fuel injection valve when the peak current is energized and the response delay time of the fuel injection valve when the hold current is energized is calculated in advance, and the required injection time is the energization time of the peak current. A fuel injection control device for an internal combustion engine, comprising: a correction time correction means for correcting the correction time by the time difference when the time is shorter. A fuel injection valve for high pressure fuel that injects fuel by opening the valve when energized;
A required injection time calculating means for calculating a required injection time according to the operating state of the internal combustion engine;
Correction time calculation means for calculating a correction time for correcting the required injection time;
A final injection time calculating means for calculating a final injection time based on the required injection time and the correction time, and energizing the fuel injection valve in response to the final injection time to open the fuel injection valve. While injecting fuel into the engine, at the start of energization, a predetermined peak current is energized to quickly open the fuel injection valve, and thereafter, a hold smaller than the peak current is held to maintain the valve open state. In a fuel injection control device for an internal combustion engine that controls a fuel injection amount by energizing a current,
The time difference between the response delay time of the fuel injection valve when the peak current is energized and the response delay time of the fuel injection valve when the hold current is energized is calculated in advance, and the final injection time is the energization time of the peak current. A fuel injection control device for an internal combustion engine, comprising: a final injection time correcting means for correcting the final injection time by the time difference when the time is shorter. The correction time calculating means calculates the correction time based on a pressure difference between a fuel pressure supplied to the fuel injection valve and an intake pressure of the internal combustion engine, and a power supply voltage for conducting the energization. 5. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device is an internal combustion engine.

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