JP5327197B2 - Injection characteristic acquisition device for fuel injection device - Google Patents

Description

  The present invention relates to an apparatus for acquiring injection characteristics of a fuel injection device.

  Conventionally, a fuel pressure sensor is provided at a fuel intake port of each injector, and various timings in a series of operations related to fuel injection of each injector are detected based on the fuel pressure detected by the fuel pressure sensor ( For example, see Patent Document 1). In the device described in Patent Document 1, the injection start timing, the maximum injection rate arrival timing, the injection end timing, and the like are detected based on the transition of the fuel pressure detected by the fuel pressure sensor.

JP 2009-57924 A

  By the way, in the thing of patent document 1, when it is going to calculate fuel injection amount and a fuel injection rate based on transition of the fuel pressure detected by a fuel pressure sensor at the time of fuel injection, transition of fuel pressure and fuel injection amount And the relationship with the fuel injection rate must be acquired in advance by a test device or the like.

  However, it is conceivable that the state of the fuel injected in the injector and the state of the fuel detected in the test apparatus are different, and the relationship between the transition of the fuel pressure and the fuel injection amount or the fuel injection rate is accurately acquired. There is a risk that it will not be possible.

  The present invention has been made in view of such circumstances, and has as its main object to provide an injection characteristic acquisition device that can accurately acquire the injection characteristic of a fuel injection device.

  The present invention employs the following means in order to solve the above problems.

The invention according to claim 1 is a pressure accumulating container for accumulating and holding high-pressure fuel, a fuel pump for pumping fuel to the pressure accumulating container, and a fuel injection valve for injecting high-pressure fuel accumulated and held in the pressure accumulating container A collection container that collects fuel injected from the fuel injection valve in a sealed state, a first pressure sensor that detects pressure in the collection container, and a volume of fuel collected by the collection container and volume detection means for a temperature sensor that volume by the volume detection means detects the temperature equal to the temperature of the fuel that will be detected, based on the temperature of the detected fuel by the temperature sensor, detected by the volume detecting means the volume of fuel, and conversion means for converting the volume or mass of fuel in the temperature of the fuel injected from the fuel injection valve, transition based on the pressure detected by the first pressure sensor The first transition acquisition means for acquiring the transition of the relative injection rate of the fuel injected from the fuel injection valve, the transition of the relative injection rate acquired by the first transition acquisition means and the conversion means converted by the conversion means the relative injection rate by converting the actual injection rate based on the volume or mass of the fuel, the relationship between the actual injection rate of the fuel injected from the fuel injection valve and the pressure detected by the first pressure sensor First characteristic acquisition means for acquiring.

  According to the above configuration, the fuel is pumped from the fuel pump to the pressure accumulating vessel, and the high-pressure fuel that is accumulated and held in the pressure accumulating vessel is injected by the fuel injection valve. The fuel injected from the fuel injection valve is collected by a sealed collection container. At this time, the pressure in the sealed collection container changes according to the volume of fuel injected from the fuel injection valve. The pressure change in the collection container is detected by the first pressure sensor.

Furthermore, the volume of the fuel collected by the collection container is detected by the volume detection means. At this time, the temperature of the fuel in the volume detection means changes from the temperature of the fuel injected from the fuel injection valve. In contrast, the temperature equal to the temperature of the fuel volume of the fuel is discovered is detected by the temperature sensor by volume detection means. Then, based on the temperature of the fuel detected by the temperature sensor, the volume of the fuel detected by the volume detecting means is converted into the volume or mass of the fuel at the temperature of the fuel injected from the fuel injection valve. Therefore, the volume or mass of the fuel corresponding to the volume or mass of the fuel actually injected from the fuel injection valve can be calculated. In addition, when converting into the volume or mass of the fuel injected from the fuel injector, an estimated value of the temperature of the fuel injected from the fuel injector may be used, or a detected value by a temperature sensor or the like may be used. Also good.

  Here, the inventors of the present application have a correlation between the transition of the pressure in the collection container detected by the first pressure sensor and the transition of the injection rate of the fuel injected from the fuel injection valve. I found. From this correlation, the transition of the relative injection rate of the fuel injected from the fuel injection valve is acquired by the first transition acquisition unit based on the transition of the pressure detected by the first pressure sensor. The relative injection rate corresponds to the fuel injection rate, and is a relative value that changes according to a change in pressure detected by the first pressure sensor.

Then, the relative injection rate is converted into the actual injection rate based on the transition of the relative injection rate acquired by the first transition acquisition means and the converted volume or mass of the fuel, and the pressure detected by the first pressure sensor. And the actual injection rate of the fuel injected from the fuel injection valve is acquired. That is, for the relative injection rate, which is a relative value corresponding to the fuel injection rate, the volume or mass of the converted fuel corresponding to the volume or mass of fuel actually injected from the fuel injection valve is By applying, the relationship between the pressure detected by the first pressure sensor and the actual fuel injection rate can be accurately acquired.

  As described above, the inventors of the present invention have a correlation between the transition of the pressure in the collection container detected by the first pressure sensor and the transition of the injection rate of the fuel injected from the fuel injection valve. I found out. Specifically, the amount of increase in pressure in the collection container and the volume of fuel injected into the collection container are proportional to each other. As a result, the differential value of the pressure in the collection container and the injection rate of fuel injected into the collection container And found that there is a proportional relationship.

  In this regard, in the invention according to claim 2, in the invention according to claim 1, the first transition acquisition means indicates the transition of the differential value of the pressure detected by the first pressure sensor as the fuel injection valve. The configuration is adopted in which the change is acquired as the transition of the relative injection rate of the fuel injected from the fuel. Therefore, the relative injection rate of fuel can be acquired easily and accurately.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the second pressure sensor that detects a pressure in a fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve, Based on the transition of the pressure detected by the second pressure sensor, acquired by the second transition acquisition means for acquiring the transition of the relative injection rate of the fuel injected from the fuel injection valve and the second transition acquisition means Based on the transition of the relative injection rate and the volume or mass of the fuel converted by the conversion means, the relative injection rate is converted into an actual injection rate, and the pressure detected by the second pressure sensor and the fuel injection valve comprising a second characteristic acquisition means for acquiring a relationship between the actual injection rate of fuel injected, the.

  According to the above configuration, the pressure in the fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve is detected by the second pressure sensor. At this time, the pressure in the fuel passage reflects the fuel injection characteristics of the fuel injection valve. Specifically, the transition of the pressure in the fuel passage detected by the second pressure sensor and the transition of the injection rate of the fuel injected from the fuel injection valve have a correlation. From this correlation, the transition of the relative injection rate of the fuel injected from the fuel injection valve is acquired by the second transition acquisition means based on the transition of the pressure detected by the second pressure sensor. This relative injection rate corresponds to the fuel injection rate, and is a relative value that changes according to a change in pressure detected by the second pressure sensor.

Then, the relative injection rate is converted into the actual injection rate based on the transition of the relative injection rate acquired by the second transition acquisition unit and the converted volume or mass of the fuel, and the pressure detected by the second pressure sensor. And the actual injection rate of the fuel injected from the fuel injection valve is acquired. That is, by applying the converted volume or mass of the fuel to the relative injection rate, which is a relative value corresponding to the fuel injection rate, the pressure detected by the second pressure sensor and the actual fuel are detected. The relationship with the injection rate can be obtained accurately.

  Further, the actual injection rate can be grasped simultaneously with the fuel injection based on the pressure in the fuel passage detected by the second pressure sensor at the time of fuel injection. As a result, the fuel injection device can perform precise injection control while grasping the actual injection rate.

  The pressure in the collection container detected by the first pressure sensor is considered to directly reflect the influence of fuel injection by the fuel injection valve rather than the pressure in the fuel passage detected by the second pressure sensor. Therefore, the accuracy of the relationship between the pressure in the collection container detected by the first pressure sensor and the actual injection rate is higher than the accuracy of the relationship between the pressure in the fuel passage detected by the second pressure sensor and the actual injection rate. Get higher.

  In this regard, in the invention according to claim 4, in the invention according to claim 3, the second characteristic acquisition means based on the relationship between the pressure acquired by the first characteristic acquisition means and the actual injection rate. A configuration is adopted in which correction means for correcting the relationship between the pressure acquired by the above and the actual injection rate is provided. Therefore, the relationship between the pressure detected by the second pressure sensor and the actual fuel injection rate can be corrected so as to improve the accuracy.

The invention according to claim 5 is a pressure accumulating container for accumulating and holding high-pressure fuel, a fuel pump for pumping fuel to the pressure accumulating container, and a fuel injection valve for injecting high-pressure fuel accumulated and held in the pressure accumulating container A collection container that collects fuel injected from the fuel injection valve in a sealed state, and a second pressure sensor that detects a pressure in a fuel passage between the pressure accumulation container and the injection hole of the fuel injection valve If the volume detection means for detecting the volume of fuel that has been collected by the collection container, a temperature sensor for detecting a temperature equal to the temperature of the fuel volume is discovered by the volume detection means is detected by said temperature sensor was based on the temperature of the fuel, the volume of the detected fuel by the volume detection means, and conversion means for converting the volume or mass of fuel in the temperature of the fuel injected from the fuel injection valve, the second Second transition acquisition means for acquiring a transition of a relative injection rate of fuel injected from the fuel injection valve based on a transition of pressure detected by a force sensor; and a relative injection acquired by the second transition acquisition means. The relative injection rate is converted into an actual injection rate based on the rate transition and the volume or mass of the fuel converted by the conversion means, and the pressure detected by the second pressure sensor and the fuel injection valve are injected. a second characteristic acquisition unit operable to acquire the relation between the actual injection rate of the fuel that is characterized in that it comprises.

  According to the said structure, since the structure similar to the invention of Claim 3 is provided, there can exist an effect similar to the invention of Claim 3.

  According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the second pressure sensor that detects a pressure in a fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve, Based on the transition of the pressure detected by the second pressure sensor, acquired by the second transition acquisition means for acquiring the transition of the relative injection rate of the fuel injected from the fuel injection valve and the second transition acquisition means Based on the transition of the relative injection rate and the relationship acquired by the first characteristic acquisition means, the relationship between the pressure detected by the second pressure sensor and the actual injection rate of the fuel injected from the fuel injection valve And third characteristic acquisition means for acquiring.

  According to the above configuration, the pressure in the fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve is detected by the second pressure sensor, as in the third aspect of the invention. And the transition of the relative injection rate of the fuel injected from the fuel injection valve is acquired by the second transition acquisition means based on the transition of the pressure detected by the second pressure sensor.

  Here, as described above, the relationship between the pressure in the collection container detected by the first pressure sensor and the actual fuel injection rate is acquired by the first characteristic acquisition unit. The accuracy of the relationship between the pressure acquired by the first characteristic acquisition unit and the actual fuel injection rate is calculated by the second characteristic acquisition unit based on the pressure in the fuel passage detected by the second pressure sensor. It becomes higher than the accuracy of the relationship between the pressure and the actual fuel injection rate. Therefore, the second pressure is obtained by applying the relationship between the pressure acquired by the first characteristic acquisition means and the actual fuel injection rate to the relative fuel injection rate, which is a relative value corresponding to the fuel injection rate. It is possible to accurately acquire the relationship between the pressure detected by the sensor and the actual fuel injection rate.

The block diagram which shows the control apparatus with which an injection characteristic acquisition apparatus is applied. The schematic diagram which shows a fuel-injection apparatus and the injection characteristic acquisition apparatus. The schematic diagram which shows a part of injection characteristic acquisition apparatus. The figure which shows the outline | summary of the procedure which learns an injection rate model. The flowchart which shows the process sequence of injection rate model learning. The flowchart which shows the process sequence of injection rate model preparation in a pressure vessel. The figure which shows the aspect which produces an injection rate model.

  Hereinafter, an embodiment embodying an injection characteristic acquisition device will be described with reference to the drawings. In addition, the apparatus of this embodiment is applied to the common rail type fuel injection system (high pressure injection fuel supply system) for a diesel engine, for example. This apparatus is applied to a fuel injection system that directly supplies high pressure fuel (for example, light oil having an injection pressure of “1000 atm” or more) to a combustion chamber in a cylinder of a diesel engine.

  First, with reference to FIG. 1, an outline of a control device of a common rail fuel injection control system (vehicle engine system) according to the present embodiment will be described. Note that a multi-cylinder (for example, in-line 4-cylinder) engine for automobiles is assumed as the engine of the present embodiment. Specifically, it is a 4-stroke reciprocating diesel engine.

  As shown in the figure, this control device (Electric Control Unit) takes in sensor outputs (detection results) from various sensors and controls the drive of each device constituting the fuel supply system based on these sensor outputs. It is configured as follows. The control device (engine control ECU) is configured with a known microcomputer, grasps the operating state of the target engine and the user's request based on the detection signals of various sensors, and according to the engine intake adjustment valve and By operating various actuators such as injectors, various controls related to the engine are performed in an optimal manner according to the situation at that time.

  A microcomputer mounted on a control device basically includes a CPU (basic processing device) that performs various calculations, and a RAM (Random Access) as a main memory that temporarily stores data during the calculation, calculation results, and the like. Memory (ROM), ROM as a program memory (read-only storage device), EEPROM (electrically rewritable non-volatile memory) as data storage memory, and backup RAM (backup power supply such as in-vehicle battery even after main power supply of ECU is stopped) Memory, which is constantly supplied with power), signal processing devices such as A / D converters and clock generation circuits, various arithmetic devices such as input / output ports for inputting / outputting signals to / from the outside, and storage devices , A signal processing device, a communication device, a power supply circuit, and the like. The ROM stores various programs and control maps related to engine control including programs related to injection characteristic acquisition and injection command correction, and the data storage memory (for example, EEPROM) stores design data of the target engine. Various kinds of control data and the like are stored in advance.

  Based on various sensor outputs (detection signals) input at any time, the control device generates torque (required torque) to be generated on the output shaft of the engine at that time, and thus a required fuel injection amount Q for satisfying the required torque. And the required injection start timing T is calculated. For example, the actual pressure Pc in the fuel passage between the common rail and the injection hole of the injector is detected by a fuel pressure sensor provided in the injector of the engine. The control device calculates the required fuel injection amount Q and the required injection start timing T according to the engine operating state from time to time, the amount of accelerator pedal operation by the driver, and the like.

  Then, the command injection period Tq and the command injection start timing Tc are calculated by applying the required fuel injection amount Q, the request injection start timing T, and the actual pressure Pc to the injection rate model M provided in the control device. As a result, based on these command injection period Tq and command injection start timing Tc, fuel is injected by the injector, and the output torque of the target engine is controlled to the target value.

  During this injection, the actual pressure Pc is detected by the fuel pressure sensor, and the actual fuel injection amount Qr, the actual injection start timing Tr, and the like can be estimated by the injection rate model M based on the transition of the actual pressure Pc. Based on the actual fuel injection amount Qr and the actual injection start timing Tr, the next fuel injection may be controlled, or the actual injection rate is grasped simultaneously with the fuel injection based on the actual pressure Pc. Fuel injection may be controlled.

  Next, an outline of processing for creating the injection rate model M will be described.

  In the present embodiment, based on the actual pressure Pc detected by the fuel pressure sensor, a predetermined time in a series of operations related to the fuel injection of the injector, specifically, the injection start time tsta, the injection rate maximum arrival time tinc, and the injection rate are maximized. After that, the injection rate lowering start time tdec, the injection end time tend, and the maximum injection rate dQmax are learned.

  The input processing unit I performs a filtering process of passing the output (actual pressure Pc) of the fuel pressure sensor through a low-pass filter, and removes high-frequency noise from the output. Then, the pressure increasing component due to the pumping of the fuel from the pump is removed from the processed data (back air correction). Specifically, in the engine, when fuel injection is performed in one cylinder, an increase in fuel pressure in a cylinder where fuel injection is not performed is subtracted from the fuel pressure in the cylinder where fuel injection is performed. . Further, the input processing unit I removes the pressure pulsation generated at the start of injection by the injector (nozzle valve opening) from the output of the fuel pressure sensor (valve opening pressure pulsation compensation). Further, in the case where a plurality of stages of injection are performed by the injector in one combustion stroke, the pressure pulsation caused by the previous stage of injection is removed (front stage injection pressure pulsation compensation).

  The analysis unit A detects each time related to fuel injection based on the pressure transition processed as described above. First, the analysis unit A calculates a first-order differential value and a second-order differential value at each time for the pressure transition. When the second-order differential value is smaller than the negative threshold value K, the time at that time is detected as the injection start time tsta. In that case, the period from the start of injection until the pressure propagates to the fuel pressure sensor is taken into account (pressure propagation delay return). Further, the analysis unit A detects the time as the injection end time tend when the previous value of the first-order differential value is positive and the first-order differential value (current value) is smaller than the negative threshold value. At this time, the period from the end of injection until the pressure propagates to the fuel pressure sensor is taken into account (pressure propagation delay return). Furthermore, when the previous value of the first-order differential value is negative and the first-order differential value (current value) is greater than a positive threshold value, the analysis unit A detects that time as the maximum injection rate arrival time tinc. . The analysis unit A detects a time that is a predetermined time before the injection end time tend as the injection rate decrease start time tdec. The method for detecting each time is not limited to these methods, and various methods can be used.

  The learning unit L learns (stores) the injection start time tsta, the injection rate maximum arrival time tinc, the injection rate lowering start time tdec, and the injection end time tend. Then, the transition of the relative injection rate is acquired based on these times. This relative injection rate corresponds to the fuel injection rate, and is a relative value that changes according to a change in the actual pressure Pc detected by the fuel pressure sensor. Further, the learning unit L learns (stores) the maximum injection rate dQmax by converting the relative injection rate into the actual injection rate based on the injection rate model learning described later. These actual injection rate and maximum injection rate dQmax are absolute values representing the magnitude of the actual injection rate.

  The control device creates the injection rate model M reflecting the parameters (each time and the maximum injection rate) learned by the learning unit L. An injection rate model M is used in the fuel injection control of the fuel injection device.

  FIG. 2 is a schematic diagram showing a fuel injection device and an injection characteristic acquisition device. As shown in the figure, the fuel injection device 10 includes a fuel pump 11, a common rail 12, a fuel pipe 13, and an injector 14.

  The fuel pump 11 includes a high-pressure pump and a low-pressure pump, and is configured to pressurize and discharge the fuel pumped up from the fuel tank by the low-pressure pump. The fuel pumped from the fuel tank by the fuel pump 11 is pressurized and supplied (pressure fed) to the common rail 12 (pressure accumulator). The common rail 12 stores the fuel pumped from the fuel pump 11 in a high pressure state, and each injector corresponding to each cylinder through each fuel pipe 13 (high pressure fuel passage) provided corresponding to the cylinder of the engine. 14 (fuel injection valves).

  Note that an orifice (throttle portion of the fuel pipe 13) that reduces fuel pulsation transmitted to the common rail 12 through the fuel pipe 13 is provided at a connection portion between the common rail 12 and the fuel pipe 13. For this reason, the pressure pulsation in the common rail 12 can be reduced, and fuel can be supplied to each injector 14 at a stable pressure. The fuel discharge port of the injector 14 is connected to a pipe for returning excess fuel to the fuel tank.

  The injection characteristic acquisition device 20 includes a pressure vessel 21, a guide pipe 22, and a flow meter 23. Each injector 14 is connected to each pressure vessel 21 (collection vessel). The pressure vessel 21 is a hollow vessel that can withstand high pressure, and is sealed so that the internal pressure does not leak to the outside. The tip (injection hole) of the injector 14 is exposed inside the pressure vessel 21, and fuel is injected into the pressure vessel 21 by the injector 14. The fuel injected into the pressure vessel 21 is collected along the inner wall of the pressure vessel 21 to the lower part.

  The upper end (one end) of each induction pipe 22 is connected to the lower part of each pressure vessel 21, and the lower end (the other end) of each induction pipe 22 is connected to a flow meter 23. The fuel collected in the lower part of the pressure vessel 21 is guided to the flow meter 23 through the guide pipe 22.

  FIG. 3 is a schematic diagram showing a part of the injection characteristic acquisition device 20. As shown in the figure, the injection characteristic acquisition device 20 includes a first pressure sensor 26 provided in each pressure vessel 21, a second pressure sensor 16 and a second temperature sensor 17 provided in each injector 14, and each flow meter. 23, a first temperature sensor 27 provided at 23, and a PC (Personal Computer) 25.

  The second pressure sensor 16 (second pressure sensor) is provided in the vicinity of the fuel intake port connected to the fuel pipe 13 in the injector 14. The second pressure sensor 16 detects the fuel pressure at the fuel intake port. The second pressure sensor 16 is not limited to detecting the pressure in the vicinity of the fuel intake port, but may be any sensor that detects the pressure in the fuel passage between the common rail 12 and the injection hole of the injector 14.

  The second temperature sensor 17 is provided in the vicinity of the fuel intake port in the injector 14. The second temperature sensor 17 detects the temperature of the fuel at the fuel intake port. Note that the second temperature sensor 17 is not limited to the vicinity of the fuel intake port but may be provided, for example, in the fuel pipe 13 or the common rail 12 as long as the fuel having a temperature equal to the temperature of the fuel in the injector 14 circulates. Good.

  The first pressure sensor 26 (first pressure sensor) is provided in the pressure vessel 21. The first pressure sensor 26 detects the pressure in the pressure vessel 21. Since the pressure vessel 21 is sealed, the pressure in the pressure vessel 21 changes when fuel is injected from the injector 14 into the pressure vessel 21. Therefore, the first pressure sensor 26 can detect a pressure change accompanying the fuel injection by the injector 14.

  The flow meter 23 is a flow meter capable of detecting a minute flow rate, and detects the volume flow rate of the fluid passing through the flow meter 23. The flow meter 23 detects the volume flow rate of the fuel guided to the flow meter 23 through the guide pipe 22, that is, the fuel injected from the injector 14.

  The first temperature sensor 27 (temperature sensor) is provided inside the flow meter 23 and detects the temperature of the fuel passing through the flow meter 23. That is, the first temperature sensor 27 detects the temperature of the fuel when the flow meter 23 detects the flow rate of the fuel. Note that the first temperature sensor 27 is not limited to the inside of the flow meter 23 and may be provided, for example, in the induction pipe 22 as long as the fuel having a temperature equal to the temperature of the fuel in the flow meter 23 flows. .

  The PC 25 is a computer that constitutes a test apparatus, a CPU (basic processing device) that performs various calculations, a RAM as a main memory that temporarily stores data in the middle of the calculation, calculation results, and the like, and a ROM as a program memory , Data storage devices, signal processing devices such as A / D converters and clock generation circuits, input / output ports for inputting / outputting signals to / from the outside, various arithmetic devices, signal processing devices, etc. , A communication device, a power supply circuit, and the like.

  The outputs of the second pressure sensor 16, the second temperature sensor 17, the first pressure sensor 26, the flow meter 23, and the first temperature sensor 27 are input to the PC 25. The PC 25 detects the volume of fuel that has passed through the flow meter 23, that is, the volume of fuel injected by the injector 14 by integrating the flow rate of the fuel detected by the flow meter 23. As described above, the flow meter 23 and the PC 25 constitute a volume detecting means for detecting the volume of the fuel collected by the pressure vessel 21.

  Further, the PC 25 converts the volume of the fuel detected by the flow meter 23 into the volume of the fuel injected from the injector 14 based on the outputs of the various sensors, and the relative injection of the fuel injected from the injector 14. Get rate. The relationship between the pressure detected by the first pressure sensor 26 and the actual injection rate of the fuel injected from the injector 14 based on the transition of the relative injection rate and the converted fuel volume (injection rate model). ) To get.

  FIG. 4 is a diagram showing an outline of a procedure for learning such an injection rate model. When fuel injection is performed by the injector 14, the second pressure sensor 16 provided in the injector 14 detects a change in pressure as shown on the upper side of FIG. As described with reference to FIG. 1, the injection start time tsta, the injection rate maximum arrival time tinc, the injection rate drop start time tdec, and the injection end time tend are learned based on this pressure transition. Based on these times, the transition of the relative injection rate (the broken line on the right side of the figure) is acquired.

  Further, when the fuel is injected by the injector 14, the first pressure sensor 26 provided in the pressure vessel 21 detects the pressure transition as shown in the lower side of the figure. That is, when the fuel is injected from the injector 14 into the sealed pressure vessel 21, the pressure in the pressure vessel 21 increases according to the volume of the injected fuel.

  Here, the inventors of the present application have found that the amount of increase in pressure (total change amount) in the pressure vessel 21 and the volume of fuel injected into the pressure vessel (total injection volume) are in a proportional relationship. . For this reason, the differential value of the pressure in the pressure vessel 21 and the injection rate, which is the differential value of the fuel volume, are in a proportional relationship. Therefore, the change in the differential value of the pressure represents the relative change in the injection rate, that is, the relative injection rate (solid line on the right side of the figure).

  Since the integral value of the relative injection rate (area below the curve) represents the volume of the fuel, by applying the volume of the fuel detected by the flow meter 23 to this, each of the relative injection rates described above is applied. Is converted into an actual injection rate. At this time, the temperature of the fuel passing through the flow meter 23 is different from the temperature of the fuel injected by the injector 14. Therefore, since the volume of the fuel changes due to a change in the temperature of the fuel, when the volume of the fuel detected by the flow meter 23 is applied as it is to the integral value of the relative injection rate, the actual injection rate that is acquired is obtained. May be inaccurate.

  Therefore, in the present embodiment, the flow meter 23 detects the detection value based on the detection value of the first temperature sensor 27 provided in the flow meter 23 and the detection value of the second temperature sensor 17 provided in the injector 14. The volume of fuel is converted into the volume of fuel injected from the injector 14. Then, the converted fuel volume is applied to the integral value of the relative injection rate to convert each relative injection rate into an actual injection rate. Therefore, the relationship between the pressure detected by the second pressure sensor 16 provided in the injector 14 and the actual fuel injection rate, and the pressure detected by the first pressure sensor 26 provided in the pressure vessel 21 and the actual fuel. The relationship with the injection rate can be obtained accurately.

  FIG. 5 is a flowchart showing the processing procedure of such injection rate model learning. This series of processing is executed by the PC 25 during fuel injection by the injector 14.

  First, an injection rate model is created based on the output of the second pressure sensor 16 of the injector 14, and the temperature of the fuel is detected by the second temperature sensor 17 of the injector 14 (S11). Specifically, as described with reference to FIG. 1, the transition of the relative injection rate is acquired based on each time related to fuel injection. Subsequently, an injection rate model (transition of relative injection rate) is created based on the output of the first pressure sensor 26 of the pressure vessel 21 (S12). Details of the process of creating the injection rate model will be described later.

  The temperature of the fuel passing through the flow meter 23 is detected by the first temperature sensor of the flow meter 23, and the volume of fuel injected by the injector 14 is detected based on the output of the flow meter 23 (S13). Specifically, by integrating the flow rate detected by the flow meter 23, the volume of fuel passing through the flow meter 23, that is, the volume of fuel injected by the injector 14 is detected.

  Then, the volume of fuel detected by the flow meter 23 is converted to the volume of fuel injected from the injector 14 (S14). Specifically, the coefficient of thermal expansion (volume change rate with respect to temperature change) determined by the type of fuel, the temperature of the fuel detected by the first temperature sensor 27 of the flow meter 23, and the second temperature sensor 17 of the injector 14 Based on the detected temperature of the fuel, the volume of the fuel is converted.

  Subsequently, the unit of the injection rate model based on the output of the first pressure sensor 26 of the pressure vessel 21 is converted into the unit of the actual injection rate using the converted volume of fuel (S15). Specifically, the converted fuel volume is applied to the integral value of the relative injection rate in the pressure vessel 21 (the area below the curve) to convert the relative injection rate into an actual injection rate. That is, the actual injection rate and the maximum injection rate in the fuel injection of the injector 14 are calculated. Furthermore, the relationship between the pressure detected by the first pressure sensor 26 and the actual injection rate is acquired.

  Using the converted fuel volume, the unit of the injection rate model based on the output of the second pressure sensor 16 of the injector 14 is converted to the unit of the actual injection rate (S16). Specifically, the converted fuel volume is applied to the integral value of the relative injection rate at the injector 14 (the area below the curve) to convert the relative injection rate into an actual injection rate. That is, the actual injection rate and the maximum injection rate in the fuel injection of the injector 14 are calculated. Furthermore, the relationship between the pressure detected by the second pressure sensor 16 and the actual injection rate is acquired. Thereafter, this series of processing ends.

  The process of S11 corresponds to the process as the second transition acquisition unit, the process of S12 corresponds to the process as the first transition acquisition unit, the process of S14 corresponds to the process as the conversion unit, and the process of S15 Corresponds to the process as the first characteristic acquisition unit, and the process of S16 corresponds to the process as the second characteristic acquisition unit.

  FIG. 6 is a flowchart showing a processing procedure for creating an injection rate model in the pressure vessel. This series of processing is executed by the PC 25 during fuel injection by the injector 14.

  First, the output of the first pressure sensor 26 of the pressure vessel 21 is low-pass filtered (S121), and the processed data is differentiated (S122). Thereby, the curve of the differential value transition of the pressure shown on the lower side of the figure is obtained from the curve of the pressure transition shown on the upper side of FIG.

  Subsequently, a horizontal line is drawn along the apex of the differentiated curve (S123). That is, as shown in FIG. 7, a horizontal line H is drawn so as to pass through the average height of the vertices of the curve. As a method of drawing the horizontal line H, in the curve of the differential value transition of pressure, it may be drawn so as to pass through a point where the differentiated value changes from a positive value to 0 or a negative value, or the differentiated value. May be drawn through points that change from 0 or a positive value to a negative value, or may be drawn so as to connect those points.

  Further, a point having a height of 25% and a point having a height of 75% are connected with a straight line (S124). That is, as shown in FIG. 7, a point P11 having a height of 25% and a point P12 having a height of 75% are connected by a straight line L1 and a point having a height of 25% with respect to the vertex (horizontal line H). P21 is connected to a point P22 having a height of 75% by a straight line L2. These points P11, P12, P21, and P22 are obtained by expediently determining the points at both ends of the straight line portion in the curve, and the positions of the respective points are set based on the specifications of the injector 14, experimental results, and the like. Is done. For this reason, the positions of these points are not limited to the heights of 25% and 75%, and heights of 30% and 70% may be used. Further, inflection points may be obtained in the curve of the differential value transition of the pressure, and the points P11, P12, P21, and P22 may be used.

  Then, intersections between the straight lines L1, L2 and the zero point and intersections between the straight lines L1, L2 and the horizontal line H are calculated (S125). As shown in FIG. 7, the intersection point P13 between the straight line L1 and the zero point, the intersection point P14 between the straight line L1 and the horizontal line H, the intersection point P23 between the straight line L2 and the zero point, and the intersection point P24 between the straight line L2 and the horizontal line H are calculated. . These points P13, P14, P24, and P23 correspond to the injection start time tsta, the injection rate maximum arrival time tinc, the injection rate drop start time tdec, and the injection end time tend, respectively. Then, the transition of the relative injection rate is acquired based on these times. Thereafter, this series of processing ends. In addition, the process of S121-S125 is equivalent to the process as a 1st transition acquisition means.

  The embodiment described above has the following advantages.

  The fuel injected from the injector 14 is collected by the pressure vessel 21 in a sealed state. At this time, the pressure in the sealed pressure vessel 21 changes according to the volume of fuel injected from the injector 14, and this change is detected by the first pressure sensor 26. Further, the volume of the fuel collected by the pressure vessel 21 is detected by the flow meter 23. When the fuel volume is detected by the flow meter 23, the temperature of the fuel is detected by the first temperature sensor 27. Based on the temperature of the fuel detected by the first temperature sensor 27, the volume of the fuel detected by the flow meter 23 is converted into the volume of the fuel injected from the injector 14. Therefore, the volume of fuel corresponding to the volume of fuel actually injected from the injector 14 can be calculated.

  The transition of the pressure in the pressure vessel 21 detected by the first pressure sensor 26 and the transition of the injection rate of the fuel injected from the injector 14 have a correlation. From this correlation, the transition of the relative injection rate of the fuel injected from the injector 14 is acquired based on the transition of the pressure detected by the first pressure sensor. Then, based on the obtained transition of the relative injection rate and the converted volume of the fuel, the relationship between the pressure detected by the first pressure sensor 26 and the actual injection rate of the fuel injected from the injector 14 is obtained. Is done. That is, by applying the converted volume of fuel corresponding to the volume of fuel actually injected from the injector 14 to the relative injection rate, which is a relative value corresponding to the fuel injection rate, The relationship between the pressure detected by the first pressure sensor 26 and the actual fuel injection rate can be accurately acquired.

  The amount of increase in pressure in the pressure vessel 21 and the volume of fuel injected into the pressure vessel 21 are proportional to each other, so that the differential value of the pressure in the pressure vessel 21 and the fuel injected into the pressure vessel 21 There is a proportional relationship with the injection rate. In this regard, the transition of the differential value of the pressure detected by the first pressure sensor 26 is acquired as the transition of the relative injection rate of the fuel injected from the injector 14. Therefore, the relative injection rate of fuel can be acquired easily and accurately.

  The transition of the pressure in the injector 14 detected by the second pressure sensor 16 and the transition of the injection rate of the fuel injected from the injector 14 have a correlation. From this correlation, the transition of the relative injection rate of the fuel injected from the injector 14 is acquired based on the transition of the pressure detected by the second pressure sensor 16. Then, based on the obtained transition of the relative injection rate and the converted volume of the fuel, the relationship between the pressure detected by the second pressure sensor 16 and the actual injection rate of the fuel injected from the injector 14 is obtained. Is done. That is, the pressure detected by the second pressure sensor 16 and the actual fuel injection are applied to the relative fuel injection rate, which is a relative value corresponding to the fuel injection rate, by applying the converted fuel volume. The relationship with the rate can be obtained accurately.

  Based on the pressure in the injector 14 detected by the second pressure sensor 16 at the time of fuel injection, the actual injection rate can be grasped simultaneously with the fuel injection. As a result, the fuel injection device 10 can perform precise injection control while grasping the actual injection rate.

  It is not limited to the said embodiment, For example, it can also implement as follows.

  In the above embodiment, the temperature of the fuel in the injector 14 is detected by the second temperature sensor 17, but the temperature of the fuel in the injector 14 may be estimated based on the pressure of the fuel or the like.

  In the above embodiment, the converted fuel volume is applied to the integral value of the relative injection rate in the pressure vessel 21 to convert the relative injection rate into the actual injection rate (S15 in FIG. 5). The process of converting the relative injection rate into the actual injection rate (S16 in FIG. 5) was performed by applying the volume of the fuel to the integral value of the relative injection rate in the injector 14. However, only one of these processes may be executed.

  The pressure in the pressure vessel 21 detected by the first pressure sensor 26 is considered to directly reflect the influence of fuel injection by the injector 14 rather than the pressure in the injector 14 detected by the second pressure sensor 16. . Therefore, the accuracy of the relationship between the pressure in the pressure vessel 21 detected by the first pressure sensor 26 and the actual injection rate is the relationship between the pressure in the injector 14 detected by the second pressure sensor 16 and the actual injection rate. Higher than accuracy.

  In this regard, based on the relationship between the pressure acquired by the injection rate model based on the output of the first pressure sensor 26 and the actual injection rate, the pressure acquired by the injection rate model based on the output of the second pressure sensor 16 and the actual A configuration that corrects the relationship with the injection rate may be employed. According to such a configuration, the relationship between the pressure detected by the second pressure sensor 16 and the actual fuel injection rate can be corrected so as to improve accuracy. Specifically, it is effective to correct the maximum injection rate, correct the average injection rate, or partially correct the injection rate.

  In the above embodiment, the relationship between the pressure in the pressure vessel 21 detected by the first pressure sensor 26 and the actual fuel injection rate is acquired. The accuracy of the relationship between the pressure and the actual fuel injection rate is based on the accuracy of the relationship between the pressure calculated based on the pressure in the injector 14 detected by the second pressure sensor 16 and the actual fuel injection rate. Also gets higher. Therefore, the relationship between the pressure acquired by the injection rate model based on the output of the first pressure sensor 26 and the actual fuel injection rate is applied to the relative injection rate, which is a relative value corresponding to the fuel injection rate. By doing so, the relationship between the pressure detected by the second pressure sensor 16 and the actual fuel injection rate can be accurately acquired.

  In the above embodiment, the volume of the fuel detected by the flow meter 23 is converted to the volume of the fuel injected from the injector 14 based on the temperature of the fuel detected by the first temperature sensor 27. It may be converted into the mass of fuel injected from. In that case, the density and thermal expansion coefficient of the fuel are used. Based on the obtained transition of the relative injection rate and the converted mass of fuel, the pressure detected by the second pressure sensor 16 and the actual injection rate (mass injection rate) of the fuel injected from the injector 14 The relationship may be acquired.

  In the above embodiment, the fuel injection device 10 including the common rail 12 is embodied. However, the fuel injection device including a delivery pipe of a direct injection gasoline engine may be embodied.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection apparatus, 11 ... Fuel pump, 12 ... Common rail (accumulation container), 14 ... Injector (fuel injection valve), 20 ... Injection characteristic acquisition apparatus, 21 ... Pressure container (collection container), 23 ... Flow meter, 25 ... PC, 26 ... first pressure sensor, 27 ... first temperature sensor (temperature sensor).

Claims (6)

An accumulator container for accumulating and holding high-pressure fuel;
A fuel pump for pumping fuel to the pressure accumulator;
A fuel injection valve for injecting high-pressure fuel stored and held in the pressure storage container;
A collection container for collecting fuel injected from the fuel injection valve in a sealed state;
A first pressure sensor for detecting the pressure in the collection container;
Volume detection means for detecting the volume of fuel collected by the collection container;
A temperature sensor for detecting a temperature equal to the temperature of the fuel volume is discovered by the volume detection means,
Conversion means for converting the volume of the fuel detected by the volume detection means into the volume or mass of the fuel at the temperature of the fuel injected from the fuel injection valve based on the temperature of the fuel detected by the temperature sensor; ,
First transition acquisition means for acquiring a transition of a relative injection rate of fuel injected from the fuel injection valve based on a transition of pressure detected by the first pressure sensor;
Based on the transition of the relative injection rate acquired by the first transition acquisition means and the volume or mass of the fuel converted by the conversion means, the relative injection rate is converted into an actual injection rate, and the first pressure sensor a first characteristic acquisition means for acquiring the relation between the actual injection rate of fuel injected and the detected pressure from the fuel injection valve,
An injection characteristic acquisition device for a fuel injection device, comprising:   2. The fuel according to claim 1, wherein the first transition acquisition unit acquires a transition of a differential value of the pressure detected by the first pressure sensor as a transition of a relative injection rate of fuel injected from the fuel injection valve. An injection characteristic acquisition device for an injection device. A second pressure sensor for detecting a pressure in a fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve;
Second transition acquisition means for acquiring a transition of a relative injection rate of fuel injected from the fuel injection valve based on a transition of pressure detected by the second pressure sensor;
Based on the transition of the relative injection rate acquired by the second transition acquisition unit and the volume or mass of the fuel converted by the conversion unit, the relative injection rate is converted into an actual injection rate, and the second pressure sensor a second characteristic acquisition means for acquiring a relationship between the actual injection rate of fuel injected and the detected pressure from the fuel injection valve,
An injection characteristic acquisition device for a fuel injection device according to claim 1 or 2.   And correcting means for correcting the relationship between the pressure acquired by the second characteristic acquisition unit and the actual injection rate based on the relationship between the pressure acquired by the first characteristic acquisition unit and the actual injection rate. Item 4. An injection characteristic acquisition device for a fuel injection device according to Item 3. An accumulator container for accumulating and holding high-pressure fuel;
A fuel pump for pumping fuel to the pressure accumulator;
A fuel injection valve for injecting high-pressure fuel stored and held in the pressure storage container;
A collection container for collecting fuel injected from the fuel injection valve in a sealed state;
A second pressure sensor for detecting a pressure in a fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve;
Volume detection means for detecting the volume of fuel collected by the collection container;
A temperature sensor for detecting a temperature equal to the temperature of the fuel volume is discovered by the volume detection means,
Conversion means for converting the volume of the fuel detected by the volume detection means into the volume or mass of the fuel at the temperature of the fuel injected from the fuel injection valve based on the temperature of the fuel detected by the temperature sensor; ,
Second transition acquisition means for acquiring a transition of a relative injection rate of fuel injected from the fuel injection valve based on a transition of pressure detected by the second pressure sensor;
Based on the transition of the relative injection rate acquired by the second transition acquisition unit and the volume or mass of the fuel converted by the conversion unit, the relative injection rate is converted into an actual injection rate, and the second pressure sensor a second characteristic acquisition means for acquiring a relationship between the actual injection rate of fuel injected and the detected pressure from the fuel injection valve,
An injection characteristic acquisition device for a fuel injection device, comprising: A second pressure sensor for detecting a pressure in a fuel passage between the pressure accumulating container and the injection hole of the fuel injection valve;
Second transition acquisition means for acquiring a transition of a relative injection rate of fuel injected from the fuel injection valve based on a transition of pressure detected by the second pressure sensor;
Based on the transition of the relative injection rate acquired by the second transition acquisition unit and the relationship acquired by the first characteristic acquisition unit, the pressure detected by the second pressure sensor and the injection from the fuel injection valve Third characteristic acquisition means for acquiring a relationship with the actual injection rate of the fuel to be
An injection characteristic acquisition device for a fuel injection device according to claim 1 or 2.

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