JP2012149601A - Fuel injection control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device and a fuel injection control method, allowing high-accuracy control of a fuel injection amount by an injector.SOLUTION: This fuel injection control device is an electronic control unit 40 controlling the fuel injection amount of the injector 30 by use of power supplying time-fuel injection amount data that are a measurement result of a power supplying time-fuel injection amount property satisfied between a power supplying time to a fuel injection valve of the injector 30 and the fuel injection amount injected from the fuel injection valve in time of power supply. The power supplying time-fuel injection amount data are divided into at least one straight line section and at least one undulation section based on a distribution of respective measurement points of the power supplying time-fuel injection amount property, and the respective measurement points included in the undulation section are set such that the respective measurement points become denser than respective measurement points included in the straight line section.

Description

  The present invention relates to a fuel injection control device and a fuel injection control method capable of controlling the fuel injection amount of an injector.

  2. Description of the Related Art Conventionally, there is known a pressure accumulation type fuel injection system that accumulates fuel pumped by a fuel supply pump with a common rail and injects fuel accumulated with the common rail into each cylinder of an internal combustion engine from an injector (for example, Patent Document 1). reference).

  In this system, for example, signals such as intake air amount, slot valve opening, engine rotation speed, cooling water temperature, exhaust temperature, and exhaust oxygen concentration are computer processed using each sensor to correspond to the operating state of the engine. Optimal fuel is supplied to each cylinder (for example, a combustion chamber or an intake pipe) by an injector.

  The engine data such as the intake air amount and the slot valve opening described above are detected by each sensor provided and converted into an electrical signal, and then input to an electronic control unit (ECU) equipped with a computer. Is done. The electronic control unit includes, for example, hardware including a microcomputer such as a CPU, a storage device such as a RAM and a ROM, and an input / output processing circuit. The electronic control unit calculates an optimal fuel injection amount using the engine data described above, and injects fuel from the injector.

  In this system, a high fuel pressure is always accumulated in a common rail disposed near the injector by a pressure feed pump, and fuel is injected by the injector. For this reason, the injection pressure of the injector can be set without depending on the load or the engine rotational speed, whereby independent control of a plurality of injectors or multistage injection is possible.

  Incidentally, a fuel injection valve is usually built in an injector. The electronic control unit opens and closes the injector by controlling the energization time of the fuel injection valve, and controls the fuel injection amount of the injector by opening and closing the injector. This fuel injection amount is determined from the pressure of the fuel stored in the common rail and the energization time of the fuel injection valve described above, that is, the valve opening time of the fuel injection valve.

  The electronic control unit includes an energizing time (hereinafter sometimes simply referred to as “ET”) of the fuel injection valve of the injector and a fuel injection amount (hereinafter referred to simply as “Q”) of the injector. Map data (hereinafter referred to as “ET-Q map data”), which is a result of previously measured energization time-fuel injection amount characteristics (hereinafter also referred to as “ET-Q characteristics”) established between May have). When the electronic control unit controls the fuel injection amount of the injector, the electronic control unit determines the energization time for injecting the required fuel injection amount based on the ET-Q map data.

JP 2009-156140 A (published July 16, 2009)

  Due to the recent demand for higher fuel consumption, it is necessary to control the fuel injection amount with higher accuracy. Under such circumstances, the present inventors have conducted intensive studies, and in particular, when the fuel injection amount is small, the ET-Q characteristics described above are not linear and non-linear. In other words, the present inventors have found that “swell” has occurred, and that the presence of the “swell” is one of the factors that reduce the control accuracy of the fuel injection amount of the injector.

  Conventionally, the ET-Q map data, which is a measurement result of the ET-Q characteristic, has been set as having linearity even when such a fuel injection amount is small. That is, the ET-Q map data does not accurately represent “swell” existing in the ET-Q characteristic. Therefore, when the electronic control unit determines the fuel injection amount of the injector based on such ET-Q map data, the determined fuel injection amount and the injector are determined by the “swell” existing in the original ET-Q characteristic. There was a large error between the actual fuel injection amount and the fuel injection amount.

  As described above, the conventional fuel injection system has a problem that the control accuracy of the fuel injection amount of the injector by the electronic control unit is lowered.

  In view of the above problems, an object of the present invention is to provide a fuel injection control device and a fuel injection control method capable of controlling the fuel injection amount of an injector with high accuracy.

  In order to achieve the above object, a fuel injection control device according to the present invention provides an energization time established between an energization time of a fuel injection valve of an injector and a fuel injection amount injected from the fuel injection valve when energized. An energization time that is a measurement result of the fuel injection amount characteristic; a fuel injection control device that controls the fuel injection amount of the injector using the fuel injection amount data, wherein the energization time-fuel injection amount data Based on the distribution of each measurement point of the time-fuel injection amount characteristic, the measurement point is divided into at least one straight section and at least one waviness section, and each measurement point included in the waviness section is the straight section. It is set so as to be denser than each measurement point included in.

  As a result of diligent research, the present inventors have found that the swell section is a section in which the linearity does not appear in the energization time-fuel injection amount characteristic, particularly when the fuel injection amount is small. And the presence of the “swell section” was found to be one of the factors that reduce the control accuracy of the fuel injection amount of the injector.

  Conventionally, in this swell section, measurement points are set with a distribution similar to that of the straight section, even though linearity does not appear, and the energization time-fuel injection amount data accurately represents the swell section. It wasn't.

  According to the above configuration, the fuel injection of the injector is performed using the energization time-fuel injection amount data set so that each measurement point included in the undulation section is denser than each measurement point included in the straight section. Control the amount.

  For this reason, the energization time-fuel injection amount data accurately represents the swell section as compared with the conventional case.

  Therefore, when the fuel injection amount of the injector is determined on the basis of such energization time-fuel injection amount data, the determined fuel injection amount and the injector are determined by the swell that exists in the original energization time-fuel injection amount characteristic. A large error does not occur between the fuel injection amount actually injected.

  Therefore, it becomes possible to control the fuel injection amount with high accuracy.

  In the above fuel injection control device, the straight section is set as a straight line connecting two measurement points that are both ends of the straight section, and the waviness section is defined as two measurement points that are both ends of the waviness section. It is preferable that the curve is set as a curve having a undulating shape.

  According to the above configuration, the undulation section of the energization time-fuel injection amount characteristic is set as a curve having a undulation shape, and thus the undulation section is represented more accurately.

  Therefore, the control accuracy of the fuel injection amount can be further improved.

  The fuel injection control device preferably includes a storage device that stores the energization time-fuel injection amount data in advance.

  According to the above configuration, even when the energization time-fuel injection amount data is stored in advance, the measurement points are set densely only in the swell interval of the energization time-fuel injection amount characteristic, and the straight line interval is the measurement point as in the prior art. Is set to sparse.

  For this reason, the capacity of energization time-fuel injection amount data does not increase more than necessary.

  Therefore, the capacity of the storage device that stores the energization time-fuel injection amount data in advance is greatly increased, and the manufacturing cost of the fuel injection control device is not increased.

  In the fuel injection control apparatus, the injector is preferably one that injects fuel, which is pumped from a fuel supply pump and accumulated in a common rail, into each cylinder of the internal combustion engine.

  According to the above configuration, it is possible to realize a common rail fuel injection system capable of controlling the fuel injection amount with high accuracy.

  The fuel injection control method according to the present invention is a measurement result of the energization time-fuel injection amount characteristic established between the energization time of the injector to the fuel injection valve and the fuel injection amount injected from the fuel injection valve when energized. A fuel injection control method for controlling the fuel injection amount of the injector using the energization time-fuel injection amount data, wherein the energization time-fuel injection amount data includes each of the energization time-fuel injection amount characteristics. Based on the distribution of measurement points, the measurement points are divided into at least one straight section and at least one undulation section, and each measurement point included in the undulation section is more than each measurement point included in the straight section. It is set to be dense.

  According to said structure, there can exist an effect similar to said fuel injection control apparatus.

  As described above, the fuel injection control device according to the present invention is the energization time-fuel injection established between the energization time to the fuel injection valve of the injector and the fuel injection amount injected from the fuel injection valve when energized. A fuel injection control device for controlling the fuel injection amount of the injector using energization time-fuel injection amount data which is a measurement result of a quantity characteristic, wherein the energization time-fuel injection amount data is the energization time-fuel Based on the distribution of each measurement point of the injection quantity characteristic, it is divided into at least one straight section and at least one undulation section, and each measurement point included in the undulation section is included in the straight section. It is set to be denser than each measurement point.

  As described above, the fuel injection control method according to the present invention is the energization time-fuel injection established between the energization time to the fuel injection valve of the injector and the fuel injection amount injected from the fuel injection valve when energized. A fuel injection control method for controlling the fuel injection amount of the injector using energization time-fuel injection amount data which is a measurement result of a quantity characteristic, wherein the energization time-fuel injection amount data is the energization time-fuel Based on the distribution of each measurement point of the injection quantity characteristic, it is divided into at least one straight section and at least one undulation section, and each measurement point included in the undulation section is included in the straight section. It is set to be denser than each measurement point.

  Therefore, there is an effect that the fuel injection amount of the injector can be controlled with high accuracy.

1 is an overall configuration diagram of a fuel injection system according to an embodiment of the present invention. It is sectional drawing of the injector provided in the said fuel-injection system. It is explanatory drawing for demonstrating operation | movement of the said injector (at the time of no injection). It is explanatory drawing for demonstrating operation | movement of the said injector (at the time of injection start). It is explanatory drawing for demonstrating operation | movement of the said injector (at the time of completion | finish of injection). It is a graph which shows the wave | interval area of an ET-Q characteristic. It is a graph which shows the whole ET-Q characteristic. It is a graph which shows the other whole of an ET-Q characteristic. 4 is a graph showing the relationship between engine speed and engine output, and the relationship between engine speed and engine shaft torque (prior art). 3 is a graph showing the relationship between the engine speed and the engine output, and the relationship between the engine speed and the shaft torque of the engine (the present invention). It is a block diagram of the electronic control unit which concerns on one Embodiment of this invention.

  An embodiment of the present invention will be described below with reference to FIGS.

  First, the configuration of a fuel injection system 1 according to an embodiment of the present invention will be described with reference to FIG. The fuel injection system 1 includes, for example, a plurality of injectors that inject high-pressure fuel in a common rail that stores high-pressure fuel into each cylinder of an internal combustion engine, and is applied to, for example, a four-cylinder diesel engine. . Hereinafter, this 4-cylinder diesel engine will be described as an example.

  FIG. 1 is a schematic configuration diagram of a fuel injection system 1. As shown in FIG. 1, the fuel injection system 1 includes at least a high-pressure pump (fuel supply pump) 10, a common rail 20, an injector 30, and an electronic control unit (fuel injection control device) 40. Although the fuel injection system 1 includes four injectors 30, only one injector 30 is shown for ease of viewing in FIG. 1.

(High pressure pump 10)
The high pressure pump 10 pumps high pressure fuel to the common rail 20. The high-pressure pump 10 includes a throttle valve 11, a plunger 12, and a discharge valve 13. The high-pressure pump 10 is an intake metering type that enables adjustment of the fuel discharge amount by adjusting the fuel intake amount.

  The throttle valve 11 is an electromagnetic valve for adjusting the amount of fuel pumped from the fuel tank 50 to the high-pressure pump 10 through the flow meter 61, the cementer 62, the heat exchanger 63, the pumping pump 64, and the fuel filter 65 in this order. It is. The throttle valve 11 is a normally open type including, for example, a coil and a valve body, and operates so that the valve body opens a fuel supply path when no current flows through the coil. That is, the throttle valve 11 operates to reduce the amount of fuel pumped up by the high-pressure pump 10 by moving the valve body in proportion to the magnitude of the current flowing through the coil. The magnitude of the current flowing through the coil is controlled by the electronic control unit 40. Thereby, the intake amount of fuel of the high-pressure pump 10, that is, the discharge amount is adjusted.

  As described above, the intake pipe connecting the fuel tank 50 and the throttle valve 11 is provided with the flow meter 61, the cementer 62, the heat exchanger 63, the pumping pump 64, and the fuel filter 65, respectively. The flow meter 61 is for measuring the amount of fuel pumped from the fuel tank 50 by the pumping pump 64. The fuel pumped from the fuel tank 50 to the high-pressure pump 10 is sent from the high-pressure pump 10 to the common rail 20 and is finally supplied from the injector 30 to each corresponding cylinder. For this reason, the flow meter 61 can also measure the amount of fuel injected from the injector 30. Note that when the amount of fuel is measured using the flow meter 61, neither excessive fuel in the high-pressure pump 10 nor fuel that has flowed out of the limiter 21 of the common rail 20, as will be described later, returns to the fuel tank 50. It is necessary to do so. Of course, when the fuel injection system 1 is actually mounted on a vehicle or the like, it goes without saying that these fuels are returned to the fuel tank 50.

  The cementer 62 is for separating water, foreign matter and the like mixed in the fuel. The cementer 62 removes moisture, foreign matter, and the like from the fuel pumped from the fuel tank 50. Thereby, the high-pressure pump 10, the common rail 20, and the injector 30 can be protected from moisture and foreign matter.

  The heat exchanger 63 is for cooling the fuel pumped from the fuel tank 50 and lowering the temperature of the fuel. The heat exchanger 63 reduces the temperature of the fuel pumped from the fuel tank 50. Thereby, the high-pressure pump 10, the common rail 20, and the injector 30 can be protected from heat generated from high-temperature fuel.

  The pumping pump 64 is a low-pressure pump that pumps fuel from the fuel tank 50 to the high-pressure pump 10 via a suction pipe connecting the high-pressure pump 10 and the fuel tank 50. The suction pipe is provided with a fuel filter 65 that filters the fuel sucked from the fuel tank 50 and removes foreign matters.

  The plunger 12 is driven by a cam that is rotationally driven by a pump drive shaft, and reciprocates between a top dead center and a bottom dead center. The fuel in the high-pressure pump 10 is pressurized by the reciprocating motion of the plunger 12.

  The discharge valve 13 of the high pressure pump 10 is a valve for discharging pressurized fuel from the high pressure pump 10. The discharge valve 13 is configured to discharge fuel when a predetermined valve opening pressure is exceeded.

  In this way, fuel is pumped from the fuel tank 50 to the high-pressure pump 10 via the suction pipe by the pumping pump 64. The pumped fuel is sucked into the high-pressure pump 10 according to the flow control of the throttle valve 11. Further, the fuel in the high-pressure pump 10 is pressurized by the plunger 12. When the pressurized fuel pressure exceeds the valve opening pressure of the discharge valve 13, the pressurized fuel is supplied to the common rail 20 via a supply pipe that connects the high-pressure pump 10 and the common rail 20. As described above, when the fuel injection system 1 is actually mounted on a vehicle or the like, excess fuel in the high pressure pump 10 is returned from the high pressure pump 10 to the fuel tank 50 again.

(Common rail 20)
The common rail 20 is for holding and storing the high-pressure fuel supplied from the high-pressure pump 10 at the target rail pressure. The target rail pressure is determined by the electronic control unit 40 based on, for example, the operating state of the diesel engine such as the engine speed.

  Further, a limiter 21 for opening the valve when the fuel pressure in the common rail 20 exceeds a predetermined upper limit value and releasing the fuel pressure in the common rail 20 is attached to the common rail 20. As described above, when the fuel injection system 1 is actually mounted on a vehicle or the like, the fuel that has flowed out of the limiter 21 is returned to the fuel tank 50 again.

  Further, a rail pressure sensor 22 is attached to the common rail 20, and a pressure signal corresponding to the actual rail pressure indicating the actual fuel pressure in the common rail 20 is input to the electronic control unit 40.

(Injector 30)
The injector 30 is for injecting fuel accumulated in the common rail 20 into the cylinder. The injector 30 is provided in each cylinder according to the number of cylinders of the engine. The injector 30 has a fuel injection valve, and the electronic control unit 40 controls the opening and closing of the fuel injection valve to inject fuel into the cylinder. For this reason, the injector 30 is configured such that high-pressure fuel is supplied to the injector 30 via each high-pressure pipe connecting the common rail 20 and the injector 30. As described above, only one cylinder is shown in FIG.

  In the injector 30, high-pressure fuel is introduced from the common rail 20 to the fuel inlet 31 via the high-pressure pipe, and the fuel inside the injector 30 flows out again toward the fuel tank 50 from the fuel outlet 32.

(Operation of the injector 30)
FIG. 2 is a cross-sectional view showing a specific example of the injector 30. As shown in FIG. 2, the injector 30 includes a magnet 301, a valve spring 302, an armature plate 303, a valve ball 304, an A orifice 305, a Z orifice 306, a control chamber 307, a valve body 308, The valve piston 309, the nozzle spring 310, the nozzle body 311, the nozzle nut 312, and the nozzle needle 313 are provided.

  First, when the injector 30 is not injecting, as shown in FIG. 2, the switch 317 is in an open state, and the magnet 301 is not energized. Therefore, the armature plate 303 is pressed downward on the paper surface of FIG. 2 by the elastic force of the valve spring 302. The ball sheet 314 is closed by the pressing.

  A high fuel pressure by the common rail 20 is applied to the control chamber 307 via the Z orifice 306. A high fuel pressure by the common rail 20 is also applied to the nozzle needle 313.

  The nozzle needle 313 is pressed downward on the paper surface of FIG. 2 by the force due to the difference in pressure receiving area with the valve piston 309 and the elastic force of the nozzle spring 310. The nozzle sheet portion 315 is closed by the pressing.

  In this way, the injector 30 is non-injected.

  Next, when the injector 30 starts injection, the switch 317 is closed as shown in FIG. 3, and the magnet 301 is energized. Therefore, the electromagnetic force of the magnet 301 exceeds the elastic force of the valve spring 302, and the armature plate 303 is attracted to the upper side of the paper surface of FIG. The ball sheet 314 is opened by the suction.

  When the ball seat 314 is opened, the high-pressure fuel supplied from the common rail 20 to the control chamber 307 is guided to the fuel outlet 32 through the ball seat 314 and the A orifice 305. The fuel guided to the fuel outlet 32 is returned to the fuel tank 50 again.

  As a result, the high-pressure fuel 316 on the nozzle needle 313 side overcomes the force due to the difference in pressure receiving area between the nozzle needle 313 and the valve piston 309 and the elastic force of the nozzle spring 310, and the nozzle needle 313 is moved above the plane of FIG. Push up. The nozzle sheet portion 315 is opened by the push-up.

  In this way, the injector 30 starts fuel injection.

  Finally, when the injector 30 finishes the injection, as shown in FIG. 4, the switch 317 is opened again, and the energization to the magnet 301 is stopped. As a result, the electromagnetic force of the magnet 301 disappears, so that the armature plate 303 is again pressed downward on the paper surface of FIG. 2 by the elastic force of the valve spring 302. By the pressing, the ball seat 314 is closed again.

  A high fuel pressure from the common rail 20 is still applied to the control chamber 307 via the Z orifice 306. A high fuel pressure by the common rail 20 is also applied to the nozzle needle 313.

  The nozzle needle 313 is pressed again downward on the paper surface of FIG. 2 by the force due to the difference in pressure receiving area with the valve piston 309 and the elastic force of the nozzle spring 310. By the pressing, the nozzle sheet portion 315 is closed again.

  In this way, the injector 30 ends the injection.

(Electronic control unit 40)
The electronic control unit 40 detects the pressure signal of the rail pressure sensor 22, the accelerator opening signal of the accelerator opening sensor 71 for detecting the depression amount (accelerator opening) of the accelerator pedal, and the rotation angle of the crankshaft of the engine. The crank angle signal of the crank angle sensor 72 for detecting the rotation angle of the camshaft of the engine and the cam angle signal of the cam angle sensor 73 for detecting the rotation angle of the engine camshaft are input. The fuel injection control of the injector 30 is performed.

  The electronic control unit 40 includes a microcomputer including a CPU, ROM, EEPROM, RAM, etc. (not shown), and performs arithmetic processing according to a program stored in the microcomputer.

  In addition to the rail pressure sensor 22, the accelerator opening sensor 71, the crank angle sensor 72, and the cam angle sensor (cylinder discrimination sensor) 73, the electronic control unit 40 performs the fuel injection control of the injector 30. Signals may be input from various sensors such as a water temperature sensor that does not. The cylinder discrimination sensor is a sensor that detects the rotation angle of the camshaft of the engine and discriminates the cylinder that injects fuel, and the water temperature sensor is a sensor that detects the temperature of engine cooling water.

  The electronic control unit 40 uses these sensor signals to calculate an optimal injection timing, injection amount, etc. according to the engine state, generates a drive signal, and outputs this drive signal to the injector 30. When the electronic control unit 40 opens and closes the fuel injection valve of the injector 30, fuel is injected from the injector 30 and the engine is moved.

  In order to perform the fuel injection control of the injector 30 as described above, the electronic control unit 40 is configured so that the pressure of the common rail 20 follows the target rail pressure corresponding to the injection pressure of the injector 30 from the operating state of the engine. The discharge amount from 10 is calculated.

  Then, the electronic control unit 40 drives the throttle valve 11 so that the calculated discharge amount is discharged from the high-pressure pump 10. As a result, the actual rail pressure of the common rail 20 is changed to the target rail pressure.

(ET-Q map data of electronic control unit 40)
As described in the background art, the electronic control unit 40 is energized between the energizing time (ET) of the fuel injection valve of the injector 30 and the fuel injection amount (Q; Fuel Quantity) of the injector 30. It has map data (ET-Q map data), which is the result of measuring the time-fuel injection amount characteristic (ET-Q characteristic) in advance. When the electronic control unit 40 controls the fuel injection amount of the injector 30, it determines the energization time for injecting the required fuel injection amount based on the ET-Q map data (energization time-fuel injection amount data). . The ET-Q map data is stored in a non-volatile storage device such as ROM or EEPROM as described above.

  The difference between the ET-Q map data stored in the electronic control unit 40 and the conventional ET-Q map will be described below with reference to FIGS. 6 and 7.

  FIG. 6 shows that the ET-Q characteristic 101 of the injector 30 is not linear and has a non-linear section, that is, the “swell” as described in the problem to be solved by the invention. It is a graph showing this. In this graph, the horizontal axis indicates the energization time, and the vertical axis indicates the fuel injection amount. Here, a section in which this “swell” occurs is called a “swell section”, and a section having linearity is called a “straight section”.

  FIG. 7 is a graph showing the entire ET-Q characteristic 101 of the injector 30 including the “swell section” shown in FIG. As shown in FIG. 7, the ET-Q characteristic 101 of the injector 30 can be divided into three “straight sections” and one “swell section”.

  When the injector 30 has such an ET-Q characteristic 101, how to measure the ET-Q characteristic 101 and set the ET-Q map data as a measurement result will be described first. Next, the case of the electronic control unit 40 will be described.

  In the prior art, first, regarding the three “straight line sections” of the ET-Q characteristic 101, the straight line connecting the measurement point 107 and the measurement point 108, the measurement point 108 and the measurement, which are both ends of each “straight line section”. It is set to follow a straight line connecting the point 102 and a straight line connecting the measurement point 104 and the measurement point 109.

  On the other hand, one “swelling section” of the ET-Q characteristic 101 is set to follow a straight line connecting the measurement point 102, the measurement point 103, and the measurement point 104. That is, in the related art, the “waviness section” is handled as following a single straight line connecting the measurement point 102, the measurement point 103, and the measurement point 104.

  Accordingly, in the prior art, the ET-Q map data, which is the result of measuring the ET-Q characteristic 101 of the injector 30 in advance, is the measurement point 107, the measurement point 108, the measurement point 102, the measurement point 103, the measurement point 104, and It is set as four straight lines connecting measurement points 109 in this order.

  For this reason, in the prior art, as shown in FIG. 6, for example, when the fuel injection amount of the injector 30 is set to QT, the energization time of the fuel injection valve of the injector 30 is set to ET_QT1 using the ET-Q map data described above. To be determined. However, as described above, the ET-Q characteristic 101 of the injector 30 has a “swell section”, and if the fuel injection amount is originally set to QT, it is necessary to set the energization time to ET_QT2. There is. When the energization time is set to ET_QT1, the fuel injection amount actually injected from the injector 30 is QR.

  Thus, in the prior art, a large error occurs between the fuel injection amount based on the ET-Q map data and the fuel injection amount actually injected from the injector 30.

  On the other hand, in the case of the electronic control unit 40, such a large error can be prevented. That is, in the electronic control unit 40, regarding the three “straight line sections” of the ET-Q characteristic 101, a straight line connecting the measurement point 107 and the measurement point 108, a straight line connecting the measurement point 108 and the measurement point 102, respectively. It is set to follow a straight line connecting the measurement point 104 and the measurement point 109. That is, it is the same as in the prior art.

  On the other hand, regarding one “undulation section” of the ET-Q characteristic 101, in addition to the measurement point 102, the measurement point 103, and the measurement point 104, a plurality of measurement points 105 and a large number of measurement points 106 are sequentially connected. Set to follow a curve. That is, the electronic control unit 40 treats the “swell section” as following a single swell curve connecting the measurement point 102, the measurement point 103, the measurement point 104, the many measurement points 105, and the many measurement points 106. In other words, it is treated as following a curve having a wavy shape connecting two measurement points 102 and 104 that are both ends of the “waviness section”.

  It should be noted that the “swell” of this “swell section” is, for example, a curve that fluctuates up and down or increases or decreases with respect to the straight line connecting the measurement point 102 and the measurement point 104 that are both ends of the “swell section”. . In the case of FIGS. 6 and 7, the curve intersects the straight line at least once (here, intersects at the measurement point 103). Moreover, in the case of FIG. 8, it is a downward convex curve with respect to the said straight line.

  What has been described above can be said that the measurement points of the ET-Q map data are set sparse in the three “straight sections” and densely set in the “swell sections”. When the “straight section” and the “swell section” are compared, it can be said that the measurement points included in the “swell section” are set more densely than the measurement points included in the “straight section”.

  Here, “densely set” means that when the number of measurement points set as ET-Q map data is compared among a large number of measurement points obtained by measuring the ET-Q characteristic 101 in advance, “undulation” It means that there are more "sections" than "straight sections".

  For this reason, in the electronic control unit 40, as shown in FIG. 6, when the fuel injection amount of the injector 30 is set to QT, the electronic control unit 40 uses the above-described ET-Q map data to determine the fuel injection valve of the injector 30. The energization time is determined to be ET_QT2. The energization time is determined to be ET_QT2, and the fuel injection amount actually injected from the injector 30 is QT.

  Thus, in the case of the electronic control unit 40, there is no error between the fuel injection amount based on the ET-Q map data and the fuel injection amount actually injected from the injector 30.

  Therefore, the fuel injection amount of the injector 30 can be controlled with high accuracy.

  In addition, each measurement point mentioned above is acquired in the following procedures, for example. First, the energization time of the fuel injection valve of the injector 30 is changed, and the fuel injection amount of the injector 30 at each energization time is measured. This measurement is performed using the flow meter 61 as described above, and several conditions are performed for each of several fuel pressures (for example, common rail pressure).

  Based on the distribution of a large number of measurement points acquired by such a procedure, the “straight section” and “swell section” of the ET-Q characteristic 101 as described above are specified. For example, as shown in FIG. 8, a section in which the ET-Q characteristic 101 is convex downward may be referred to as a “swell section”.

  In the electronic control unit 40, as described above, the measurement points are set densely only in the “waviness section” of the ET-Q characteristic 101, and the measurement points are set sparse in the “straight section” as in the prior art. Yes. For this reason, it is avoided that the capacity of the ET-Q map data stored in advance in the electronic control unit 40 increases more than necessary. Therefore, the capacity of the storage device mounted on the electronic control unit 40 is greatly increased, and the manufacturing cost of the electronic control unit 40 is not increased.

  The ET-Q characteristics as described above are based on the injection characteristics of the reference injector, and the injection characteristics of the individual injectors are different from the reference injector due to manufacturing errors and the like. Therefore, by using the ET-Q map data that more accurately represents the original ET-Q characteristic of the injector as in the electronic control unit 40, each fuel injection amount can be made more accurate for each individual injector. It becomes possible to control well.

(Effect of the electronic control unit 40)
The effect of the electronic control unit 40 will be described. 9 and 10 are graphs showing the relationship between the engine speed and the engine output, and the relationship between the engine speed and the engine shaft torque, respectively. FIG. 9 corresponds to the prior art, and FIG. 10 corresponds to the electronic control unit 40.

  As shown in FIG. 9, in the case of the conventional technique, the engine torque of the engine has a recess in a predetermined range (1400 to 2000 rpm) of the engine speed (location indicated by A). That is, as the engine speed increases, the shaft torque of the engine increases and decreases, giving the operator a sense of incongruity.

  On the other hand, as shown in FIG. 10, in the case of the electronic control unit 40, the recess of the engine shaft torque is eliminated at the position indicated by B in FIG. 10 corresponding to the position indicated by A in FIG. It changes smoothly as the rotational speed increases. For this reason, it does not give the operator a sense of incongruity as described above.

(Configuration example of electronic control unit 40)
FIG. 11 shows a configuration example of the electronic control unit 40. As shown in FIG. 11, the electronic control unit 40 includes an input / output circuit 41, an engine control unit 42, a nonvolatile memory 43, and a data input unit 44.

  The input / output circuit 41 is connected to, for example, a CAN (Controller Area Network) 81 and exchanges data with the high-pressure pump 10, the injector 30, the accelerator opening sensor 71, the crank angle sensor 72, and the cam angle sensor 73. Communicate.

  The data input unit 44 receives the above-described ET-Q map data via the CAN 81 and the input / output circuit 41. The data input unit 44 stores the ET-Q map data in the nonvolatile memory 43.

  For example, the ET-Q map data may be encrypted when transmitted to the electronic control unit 40. In this case, when receiving the encrypted ET-Q map data, the data input unit 44 decrypts the ET-Q map data and stores it in the nonvolatile memory 43.

  For this reason, the ET-Q map data remains encrypted while being transmitted via the CAN 81. Even if a third party reads ET-Q map data from CAN 81, it is difficult to illegally use the ET-Q map data.

  The nonvolatile memory 43 has a nonvolatile feature that data is not destroyed even when the power is turned off. As the nonvolatile memory 43, for example, a flash memory, P-ROM, EP-ROM, or E2P-ROM can be used.

  The engine control unit 42 executes engine control by adjusting the fuel injection amount of the injector 30 using the ET-Q map data stored in the nonvolatile memory 43. The engine control unit 42 performs data communication with the high-pressure pump 10 and the injector 30 connected to the CAN 81 using the input / output circuit 41, for example, and executes the above-described engine control.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  For example, the present invention is an energization time which is a measurement result of an energization time-fuel injection amount characteristic established between an energization time of a fuel injection valve of an injector and a fuel injection amount injected from the fuel injection valve when energized. -Energization time for creating fuel injection amount data-A fuel injection amount data creation device, comprising a plurality of measurement points comprising a fuel injection amount measured by changing the energization time and an energization time corresponding to the fuel injection amount Means for specifying at least one straight section and at least one waviness section, and means for setting each measurement point included in the waviness section to be denser than each measurement point included in the straight section. An energization time-fuel injection amount data creation device.

  Finally, the engine control unit 42 of the electronic control unit 40 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the engine control unit 42 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program of the engine control unit 42, which is software that realizes the functions described above, is recorded so as to be readable by a computer. This can also be achieved by supplying the engine control unit 42 and the computer (or CPU or MPU) reading and executing the program code recorded on the recording medium.

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and a compact disk-ROM / MO / MD / digital video disk / compact disk-R. A disk system including an optical disk, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM can be used.

  Further, the engine control unit 42 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  According to the fuel injection control device of the present invention, the fuel injection amount of the injector that injects the high-pressure fuel in the common rail that stores high-pressure fuel into the cylinders of the internal combustion engine can be controlled with high accuracy. It is useful when applied to a working machine such as a passenger car, a vehicle such as a truck or a bus.

1 Fuel injection system 10 High-pressure pump (fuel supply pump)
20 common rail 30 injector 40 electronic control unit (fuel injection control device)

Claims (5)

The energization time-fuel injection amount data, which is the measurement result of the energization time-fuel injection amount characteristic established between the energization time of the fuel injection valve of the injector and the fuel injection amount injected from the fuel injection valve at the time of energization, A fuel injection control device for controlling the fuel injection amount of the injector,
The energization time-fuel injection amount data is divided into at least one straight section and at least one undulation section based on the distribution of the measurement points of the energization time-fuel injection amount characteristics, and the swell The fuel injection control device, wherein each measurement point included in the section is set to be denser than each measurement point included in the straight section. The straight section is set as a straight line connecting two measurement points that are both ends of the straight section,
2. The fuel injection control device according to claim 1, wherein the swell section is set as a curve having a swell shape connecting two measurement points that are both ends of the swell section.   The fuel injection control device according to claim 1, further comprising a storage device that stores the energization time-fuel injection amount data.   The fuel injection control according to any one of claims 1 to 3, wherein the injector is configured to inject fuel, which is pumped from a fuel supply pump and accumulated in a common rail, into each cylinder of the internal combustion engine. apparatus. The energization time-fuel injection amount data, which is the measurement result of the energization time-fuel injection amount characteristic established between the energization time of the fuel injection valve of the injector and the fuel injection amount injected from the fuel injection valve at the time of energization, A fuel injection control method for controlling a fuel injection amount of the injector using:
The energization time-fuel injection amount data is divided into at least one straight section and at least one waviness section based on the distribution of each measurement point of the energization time-fuel injection amount characteristic, and the straight line A fuel injection control method, wherein each measurement point included in a section is set sparse, and each measurement point included in the waviness section is set densely.

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