JP2016008514A - Common rail fuel injection system control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect whether correction information on each injector written to a control unit is correct.SOLUTION: A control unit 20 of a common rail fuel injection system comprises: a storage section 20a storing correction information set to each of a plurality of set pressures in response to injection properties per injector; a pressure selection section 20c selecting the set pressure from among the plurality of set pressure; a pressure regulation section 20d regulating a pressure in a common rail to the selected set pressure; a control section 20b exerting a fuel injection control per injector using the correction information in a state in which the pressure regulation section 20d regulates the pressure in the common rail; and a determination section 20f determining whether the correction information is correct if the control section 20b exerts the fuel injection control per injector.

Description

  The present invention relates to a control device for a common rail fuel injection system.

  In the common rail fuel injection system, high pressure fuel stored in the common rail is injected from the injector of each cylinder. Each injector has its own injection characteristics, and even when the injection is performed at the same common rail pressure and the same injection time, a difference occurs in the injection amount between the injectors. Therefore, it is necessary to correct the injection time for each injector. In Patent Document 1, in a common rail fuel supply system, an injection time correction value is calculated from an injection time correction value map based on the common rail pressure and the indicated fuel injection amount, and fuel injection is performed using the injection time correction value. In addition, it is disclosed that when the absolute value of the injection time correction value is larger than the abnormality determination value, it is determined that the fuel injection is abnormal.

JP 2013-108403 A

  Each injector is provided with a code that stores correction information set for each of a plurality of set pressures according to the injection characteristics. If the correction information of this code is not written in the control device for each injector, the injection time cannot be corrected with high accuracy for each injector. Patent Document 1 discloses that the fuel injection is determined to be abnormal when the absolute value of the injection time correction value is larger than the abnormality determination value, but this abnormality determination is to detect an injector failure or the like, It does not detect whether the correction information of each injector written in the control device is correct.

  Therefore, in this technical field, there is a demand for a control device for a common rail fuel injection system that can accurately detect whether or not written correction information for each injector is correct.

  A control device for a common rail fuel injection system according to one aspect of the present invention is a control device for a common rail fuel injection system that injects high-pressure fuel in a common rail from an injector provided for each of a plurality of cylinders in an engine. A storage unit that stores correction information set for each of a plurality of set pressures according to the injection characteristics, a pressure selection unit that selects a set pressure from a plurality of set pressures, and a pressure in the common rail are selected by the pressure selection unit. A pressure adjusting unit that adjusts to the set pressure, a control unit that performs fuel injection control using correction information for each injector while adjusting the pressure in the common rail by the pressure adjusting unit, and fuel injection control by the control unit for each injector And a determination unit that determines whether the correction information is correct or not.

  In this control device, by performing fuel injection control in a state where the pressure in the common rail is adjusted to a set pressure selected from a plurality of set pressures, only the correction information set to the selected set pressure in the fuel injection control is performed. Can be used to correct. Therefore, it is possible to make a determination by focusing on the correction information set to the set pressure, and it is possible to accurately determine whether or not the correction information is correct. As described above, the control device can accurately detect whether the correction information of each injector written is correct by determining the correction information after adjusting the pressure in the common rail to the set pressure. .

  The control device for the common rail fuel injection system according to an embodiment includes a pressure detection unit that detects a pressure in the common rail, and the pressure adjustment unit includes a set pressure selected by the pressure selection unit and a pressure in the common rail detected by the pressure detection unit. When the difference from the pressure is within the threshold, the pressure in the common rail is adjusted to the set pressure selected by the pressure selection unit. In this way, the pressure in the common rail is not greatly adjusted by adjusting the pressure in the common rail to the set pressure only when the difference between the detected pressure in the common rail and the set pressure is within the threshold value. The influence on the cleanliness of exhaust gas can be suppressed.

  In the control device for the common rail fuel injection system according to the embodiment, the pressure adjustment unit changes the pressure in the common rail by the allowable pressure change amount when adjusting the pressure in the common rail to the set pressure selected by the pressure selection unit. In this way, by changing the pressure in the common rail by the permissible pressure change amount, the pressure change amount per time in the common rail can be limited, and the change in engine sound (abnormal noise) etc. Discomfort can be reduced.

  According to the present invention, it is possible to accurately detect whether or not the correction information of each injector written is correct.

It is a schematic block diagram of the diesel engine provided with the common rail type fuel injection system concerning one embodiment. It is a block diagram which shows the control structure of the common rail type fuel injection system which concerns on one Embodiment. It is an example of each correction point set to each correction point setting pressure of the code for each injector stored in the storage unit of FIG. It is explanatory drawing of the engine rotation fluctuation amount calculated by the rotation fluctuation amount calculation part of FIG. It is a flowchart of the injector code verification in the engine ECU of FIG. It is a flowchart of the common rail pressure adjustment in engine ECU of FIG.

  Hereinafter, a control device for a common rail fuel injection system according to an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the element which is the same or it corresponds in each figure, and the overlapping description is abbreviate | omitted.

  In the present embodiment, the control device according to the present invention is applied to a control device (engine ECU [Electronic Control Unit]) of a common rail fuel injection system provided in a diesel engine for a vehicle. The engine ECU according to the present embodiment is an ECU that controls a diesel engine, and a common rail fuel injection system is one of the objects to be controlled. In particular, the engine ECU according to the present embodiment has an injector code verification function for determining whether or not the code assigned to each injector written from the outside of the engine ECU is correct. This code represents the correction information (correction point) set to each of a plurality of set pressures (correction point set pressures) according to the injection characteristics unique to the injector.

  First, the configuration of the diesel engine 1 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a diesel engine 1 including a common rail fuel injection system according to an embodiment.

  The diesel engine 1 is an in-line 6-cylinder diesel engine having 6 cylinders (first cylinder 2A, second cylinder 2B, third cylinder 2C, fourth cylinder 2D, fifth cylinder 2E, and sixth cylinder 2F). It has. Pistons 3 are accommodated in the respective cylinders 2A to 2F. Each piston 3 reciprocates in each cylinder (each cylinder) 2A to 2F. A crankshaft 4 is attached to one end of each piston 3. The crankshaft 4 converts the reciprocating motion of each piston 3 into a rotational motion. A flywheel 5 is attached to one end of the crankshaft 4. The flywheel 5 stores energy of rotational motion by the crankshaft 4 and supplies the rotational kinetic energy to drive wheels (not shown). The diesel engine 1 also includes a common rail fuel injection system 10 that injects fuel into the cylinders 2A to 2F. In this embodiment, an in-line 6-cylinder diesel engine is used, but the arrangement of the cylinders may be other arrangements such as a V type, a horizontally opposed type, and the number of cylinders may be other cylinders such as 4 cylinders. Good.

  In the intake stroke of the diesel engine 1, the piston 3 is lowered to the bottom dead center in the cylinders 2A to 2F and sucks air. In the compression stroke, the piston 3 rises to the top dead center in the cylinders 2A to 2F, and compresses and heats the air. In the expansion stroke, fuel is self-ignited by injecting fuel into the high-temperature and high-pressure air in the cylinders 2A to 2F by the common rail fuel injection system 10, and the expanded combustion gas pushes down the piston 3 to the bottom dead center. In the exhaust stroke, the piston 3 rises to the top dead center due to the inertia of the flywheel 5 and expansion in other cylinders in the cylinders 2A to 2F, and pushes the combustion gas out of the cylinders 2A to 2F. The reciprocating motion between the top dead center and the bottom dead center of the piston 3 is transmitted to the crankshaft 4, and the crankshaft 4 converts the reciprocating motion into a rotational motion.

  A common rail fuel injection system 10 will be described with reference to FIG. The common rail fuel injection system 10 includes a supply pump 11, a common rail 12, and six injectors (first injector 13A, second injector 13B, third injector 13C, fourth injector 13D, fifth injector 13E, and sixth injector 13F). It has.

  The supply pump 11 is a high-pressure pump that supplies fuel (light oil) from the fuel tank 14 to the common rail 12. The supply pump 11 pressurizes the fuel and pumps the high-pressure fuel to the common rail 12. The supply pump 11 is controlled by the engine ECU 20 to adjust the pressurized state of fuel, the supply amount, and the like. Therefore, the pressure in the common rail 12 (hereinafter referred to as “common rail pressure”) is also adjusted by the control of the supply pump 11 by the engine ECU 20.

  The common rail 12 is a tubular member that stores high-pressure fuel pumped from the supply pump 11, and extends along the six cylinders 2A to 2F arranged in series. Six injectors 13A to 13F corresponding to the respective cylinders 2A to 2F are connected to the common rail 12, and high pressure fuel is supplied to the injectors 13A to 13F, respectively. Therefore, the common rail pressure corresponds to the injection pressure from each of the injectors 13A to 13F.

  The injectors 13A to 13F are devices that are provided in the cylinders 2A to 2F and inject fuel into the cylinders 2A to 2F in a mist form. Each of the injectors 13A to 13F is an electronically controlled injector and has an electromagnetic valve. This electromagnetic valve is a normally closed valve that opens when a current is passed (when energized). In each of the injectors 13A to 13F, an electromagnetic valve is opened according to control (energization) by the engine ECU 20, and the amount of fuel injected into each of the cylinders 2A to 2F is adjusted. Therefore, the energization time of each of the injectors 13A to 13F by the engine ECU 20 corresponds to the fuel injection time of each of the injectors 13A to 13F. As described above, since the common rail pressure corresponds to the injection pressure of each injector 13A to 13F, the fuel injection amount of each injector 13A to 13F is determined by the common rail pressure and the energization time by engine ECU 20.

  Each of the injectors 13A to 13F has a unique injection characteristic. Therefore, even when the six injectors 13A to 13F inject fuel with the same common rail pressure and the same injection time, a difference in the injection amount occurs between the six injectors 13A to 13F. Therefore, in order to inject fuel of the same target injection amount at the same common rail pressure from the six injectors 13A to 13F, it is necessary to correct the injection time (energization time) according to the injection characteristics of the injectors 13A to 13F. is there. Therefore, each of the injectors 13A to 13F is provided with a code that stores information for correcting the energization time.

  The engine ECU 20 will be described with reference to FIGS. FIG. 2 is a block diagram illustrating a control configuration of the common rail fuel injection system 10 according to an embodiment. FIG. 3 is an example of each correction point set to each correction point setting pressure of the code for each injector stored in the storage unit of engine ECU 20 in FIG. FIG. 4 is an explanatory diagram of the engine rotation fluctuation amount calculated by the rotation fluctuation amount calculation unit of the engine ECU 20 of FIG.

  The engine ECU 20 is an electronic control unit that includes a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and performs overall control of the diesel engine 1. In the present embodiment, only the process for the common rail fuel injection system 10 which is one function of the engine ECU 20 will be described, and in particular, the injector code verification process will be described in detail.

  The engine ECU 20 includes a storage unit 20a in a partial area of the RAM. Further, the engine ECU 20 loads various programs stored in the ROM into the RAM and executes them by the CPU, whereby the control unit 20b, the pressure selection unit 20c, the pressure adjustment unit 20d, the rotation fluctuation amount calculation unit 20e, and the determination unit 20f. Is configured. The engine ECU 20 is connected to various sensors such as a common rail pressure sensor 30 and an engine speed sensor 31, and acquires information from the various sensors. The engine ECU 20 is connected to a supply pump 11 and first to sixth injectors 13A to 13F. The engine ECU 20 performs processing in each of the processing units 20b to 20f using information stored in the storage unit 20a and information from various sensors, and the supply pump 11 and the first to sixth injectors according to each processing. 13A-13F are controlled.

  In the present embodiment, the storage unit 20a corresponds to the storage unit described in the claims, the control unit 20b corresponds to the control unit described in the claims, and the pressure selection unit 20c corresponds to the claims. The pressure adjustment unit 20d corresponds to the pressure adjustment unit described in the claims, the determination unit 20f corresponds to the determination unit described in the claims, and the common rail pressure sensor 30. Corresponds to the pressure detector described in the claims.

  The common rail pressure sensor 30 will be described. The common rail pressure sensor 30 is a pressure detection sensor provided on the common rail 12. The common rail pressure sensor 30 detects the common rail pressure and transmits the detected common rail pressure to the engine ECU 20.

  The engine speed sensor 31 will be described. The engine rotation speed sensor 31 is a rotation speed detection sensor provided at a location where the rotation speed of the diesel engine 1 can be detected (for example, the flywheel 5). The engine speed sensor 31 detects the engine speed and transmits the detected engine speed to the engine ECU 20.

  The storage unit 20a will be described. The storage unit 20a is configured in a partial area of the RAM that can be written and read. In the storage unit 20a, correction information stored in codes assigned to the injectors 13A to 13F written from the outside of the engine ECU 20 is stored in association with the injectors 13A to 13F. Before the vehicle is shipped, the correction information of the codes of the injectors 13A to 13F that are assembled to the diesel engine 1 by the operator of the manufacturing line is written in the manufacturing line. After the vehicle is shipped, when replacing any injector due to an injector failure, etc., only the correction information for the injector code that has been replaced by a mechanic at the repair shop is written at the repair shop. It is done. If this rewriting is not performed, the correction information of the code of the injector before replacement stored in the storage unit 20a is used when correcting the energization time of the replaced injector. In addition, when the code is written, some correction information stored in the code may not be written normally. In addition, a part of the correction information stored in the code may be incorrect correction information.

  The codes given to the injectors 13A to 13F will be described. The code is a code that can store a predetermined amount of information such as a two-dimensional barcode, and stores correction information for each of the injectors 13A to 13F. This correction information is information consisting of correction points indicating the relationship between the injection amount and the energization time. The correction points are respectively set according to a plurality of predetermined common rail pressures (corresponding to injection pressures). The common rail pressure for setting the correction point is hereinafter referred to as “correction point setting pressure”. The correction point setting pressures are a plurality of pressures set within the range of pressures that can be injected by the injectors 13A to 13F, and each correction point is set corresponding to each correction point setting pressure. One or more correction points are set for one correction point set pressure according to the individual injection characteristics of the injector. For example, for one correction point set pressure, a correction point for a large injection amount, a minute injection amount Three correction points are set as correction points for the intermediate injection amount, which is an inflection point therebetween. When performing multi-stage injection such as pre-injection and after-injection in addition to main injection, the correction point for large injection amount and the correction point for medium injection amount are used for correcting the energization time of main injection, and the correction point for minute injection amount is It is used to correct the energization time for pre-injection and after-injection.

FIG. 3 shows an example of each correction point set for each correction point setting pressure, the horizontal axis is the energization time [μs (seconds)], and the vertical axis is [mm ³ / st (stroke)]. It is. In this example, there are two correction point setting pressures P1 and P2, and the correction point setting pressure P1 is lower than the correction point setting pressure P2. For the correction point setting pressure P1, a correction point RB1 for a large injection amount, a correction point RM1 for a medium injection amount, and a correction point RL1 for a small injection amount are set. For the correction point setting pressure P2, a correction point RB2 for a large injection amount, a correction point RM2 for a medium injection amount, and a correction point RL2 for a small injection amount are set. The example shown in FIG. 3 is an example, and there may be three or more correction point setting pressures. When there is no inflection point, one or two correction points are provided for the correction point setting pressure. Only a point may be set, or when there are a plurality of inflection points, four or more correction points may be set for the correction point setting pressure.

  Note that various maps used by the control unit 20b are stored in a partial area of the ROM of the engine ECU 20. As this map, for example, a map showing the relationship between the driving state of the vehicle and the common rail pressure, a map showing the relationship between the driving state of the vehicle and the injection amount of the master injector, the injection amount and energization time of the master injector for each common rail pressure It is a map which shows the relationship. The master injector is a virtual injector that serves as a reference for the injectors 13A to 13F that are actually assembled. The correction amount of each of the injectors 13A to 13F is a correction amount that is a time lengthened or shortened with respect to the energization time set for the master injector. The driving state of the vehicle can be determined from the engine load corresponding to the engine speed and the accelerator opening.

  The control unit 20b will be described. The control unit 20b refers to a map showing the relationship between the driving state of the vehicle and the common rail pressure, and sets a target common rail pressure according to the current driving state of the vehicle. Then, the control unit 20b controls the supply pump 11 so that the pressure in the common rail 12 becomes the target common rail pressure.

  The control unit 20b refers to a map showing the relationship between the driving state of the vehicle and the injection amount of the master injector, and acquires the target injection amount of the master injector corresponding to the current driving state of the vehicle. Further, the control unit 20b refers to a map showing the relationship between the injection amount of the master injector and the energization time with respect to each common rail pressure, and detects the current common rail pressure (target common rail pressure or target common rail pressure) detected by the common rail pressure sensor 30. The energization time of the master injector necessary for injecting the fuel of the target injection amount at the pressure in the vicinity) is acquired.

  In the control unit 20b, for each of the injectors 13A to 13F, the correction points set to the correction point setting pressures associated with the injectors stored in the storage unit 20a are read, and the common rail pressure is read using the correction points. An injector energization time necessary for injecting a target injection amount of fuel at the current common rail pressure detected by the sensor 30 is acquired. For example, when there is a correction point setting pressure that matches the current common rail pressure, two correction points sandwiching the target injection amount from the correction point set to the correction point setting pressure (may be one correction point) And the energization time of the injector is calculated from the two corrected correction points. If there is no correction point setting pressure that matches the current common rail pressure, two correction point setting pressures that sandwich the current common rail pressure are selected, and the target injection amount is calculated from the correction points set for the respective correction point setting pressures. Two correction points (which may be one correction point) are extracted, and the energization of the injector is performed using the extracted four correction points (three or two in total). Calculate time. The time difference between the energization time of each of the injectors 13A to 13F and the energization time of the master injector corresponds to the correction amount of the energization time of the injectors 13A to 13F. The controller 20b sequentially supplies current to the injectors 13A to 13F during the energization time of the injectors 13A to 13F in accordance with the injection timing of the injectors 13A to 13F.

  The pressure selection unit 20c, the pressure adjustment unit 20d, the rotation fluctuation amount calculation unit 20e, and the determination unit 20f, which will be described below, are each processing unit that is necessary for performing verification of the codes of the injectors 13A to 13F. This code verification is performed when the driving state of the vehicle is in a steady operation state while the ignition switch is ON (the diesel engine 1 is operating). The steady operation state is, for example, a low load operation state in which the fluctuation of the engine speed is stable within a predetermined range and the engine load corresponding to the accelerator opening is equal to or less than a predetermined value.

  The pressure selection unit 20c will be described. In the pressure selection unit 20c, one correction point setting pressure is selected from a plurality of correction point setting pressures of the code stored in the storage unit 20a, and the correction point setting pressure is used as a code verification pressure (hereinafter, “ It is called “certification pressure”). In the pressure selection unit 20c, when the verification for the selected verification pressure is completed, one correction point setting pressure is selected from the remaining correction point setting pressures and set as the next verification pressure. The pressure selection unit 20c repeats this process, and sets all the correction point setting pressures of the code stored in the storage unit 20a as the verification pressure.

  The pressure adjusting unit 20d will be described. The pressure adjustment unit 20d changes the pressure in the common rail 12 by controlling the supply pump 11, and adjusts the pressure in the common rail 12 to the verification pressure selected by the pressure selection unit 20c. Thereby, in order to perform the code verification, the pressure in the common rail 12 is forcibly adjusted to the verification pressure.

  When the pressure in the common rail 12 is forcibly adjusted to the verification pressure, a change that does not normally occur in the diesel engine 1 may occur in a short time, and various phenomena due to a sudden change in the state of the diesel engine 1 occur. May occur. For example, if the common rail pressure before the pressure adjustment and the verification pressure are greatly separated, there is a possibility that the influence on the exhaust gas cleanliness and the like will become large. In addition, when the pressure in the common rail 12 is changed to match the verification pressure, if the amount of change in pressure per time is large, a change in engine sound (abnormal noise) or the like may cause a driver in the vehicle to May cause discomfort. Further, since the load on the supply pump 11 becomes large, there is a possibility that the deterioration of the supply pump 11 is accelerated. Since the adjustment of the common rail pressure to the verification pressure is performed only for the purpose of code verification, regardless of the operating condition of the vehicle, it is necessary to suppress such deterioration of exhaust gas cleanliness and engine noise as much as possible. There is.

  Therefore, in the pressure adjustment unit 20d, the pressure in the common rail 12 is only when the pressure difference between the common rail pressure detected by the common rail pressure sensor 30 and the verification pressure before pressure adjustment is larger than the threshold value AL and smaller than the threshold value AH. The pressure adjustment to the verification pressure is started. The threshold value AL and the threshold value AH are upper limit pressure adjustment amounts that can adjust the pressure in the common rail 12. The threshold value AL and the threshold value AH have the same absolute value, the threshold value AL is a negative value, and the threshold value AH is a positive value. As a method of setting the threshold value AL and the threshold value AH, for example, the common rail pressure is adjusted to a plurality of predetermined pressures around the correction point setting pressure by an actual vehicle experiment, and exhaust according to the pressure adjustment amount up to the predetermined pressures. The gas cleanliness and the like are detected, respectively, and thresholds AL and AH that allow the influence on the exhaust gas are set from the relationship between the pressure adjustment amounts and the exhaust gas cleanliness and the like. It is preferable to set the threshold value AL and the threshold value AH after performing this vehicle test many times and collecting a lot of data.

  In the pressure adjustment unit 20d, is the absolute value of the difference between the common rail pressure detected by the common rail pressure sensor 30 and the verification pressure smaller than the allowable pressure change amount after the pressure adjustment to the verification pressure of the pressure in the common rail 12 is started? Determine whether or not. If it is determined that the absolute value of this difference is smaller than the allowable pressure change amount, the pressure adjustment unit 20d ends the pressure adjustment. On the other hand, if it is determined that the absolute value of this difference is greater than or equal to the allowable pressure change amount, the pressure adjustment unit 20d changes the allowable pressure to the previous target common rail pressure if the common rail pressure detected by the common rail pressure sensor 30 is smaller than the verification pressure. When the common rail pressure detected by the common rail pressure sensor 30 is equal to or higher than the verification pressure, the allowable pressure change amount is subtracted from the previous target common rail pressure to obtain the current target common rail pressure. To do. Then, the pressure adjusting unit 20d controls the supply pump 11 so that the pressure in the common rail 12 becomes the current target common rail pressure. The allowable pressure change amount is a pressure change amount allowed per time when the pressure in the common rail 12 is changed. As a method of setting the allowable pressure change amount, for example, the common rail pressure is changed by changing the change amount of the pressure per one time around the correction point set pressure by an actual vehicle experiment, and each pressure change amount per one time is changed. The engine abnormal noise or the like corresponding to each is detected, and the allowable pressure variation that can allow the influence on the person obtained from the relationship between the pressure variation and the engine abnormal noise or the like is set. At this time, sensory evaluation for evaluating discomfort or the like experienced by a person may be performed. This actual vehicle experiment and sensory evaluation may be performed many times, and a large amount of data may be collected before setting the allowable pressure change amount.

  The rotation fluctuation amount calculation unit 20e will be described. Before explaining the processing of the rotation fluctuation amount calculation unit 20e, the reason why the engine rotation fluctuation amount is used in the code verification will be described. When the common rail pressure is adjusted to the verification pressure, the control unit 20b sets, for each of the injectors 13A to 13F, the correction point setting pressure of the verification pressure of the code associated with each injector stored in the storage unit 20a. Read out the correction points, extract two correction points (in some cases, one correction point) sandwiching the target injection amount from each correction point, and use the extracted two correction points to energize the injector Is calculated. And in the control part 20b, according to the injection timing of each injector 13A-13F, during the energization time of each injector 13A-13F, an electric current is supplied to each injector 13A-13F sequentially. In response to energization from the control unit 20b, the injectors 13A to 13F open during the energization time and inject fuel into the cylinders 2A to 2F. Accordingly, the rotational speed of the diesel engine 1 varies.

  FIG. 4 shows an example of fluctuations in engine speed, where the horizontal axis is time and the vertical axis is engine speed. The fluctuation amount of the engine speed in the hatched region in the substantially mountain shape indicated by the reference sign C1 indicates the fluctuation amount of the engine speed according to the reciprocating motion of the piston 3 in the first cylinder 2A, and this is the fluctuation amount of the first injector 13A. This corresponds to the amount of work by the first cylinder 2A corresponding to one fuel injection. Similarly, the fluctuation amount of the engine speed in each hatched region indicated by reference numerals C2 to C6 is determined by the work performed by the second to sixth cylinders 2B to 2F in accordance with one fuel injection of the second to sixth injectors 13B to 13F. It corresponds to the amount.

  When all the codes (each correction point set to each correction point setting pressure) stored in the storage unit 20a are correct codes given to the injectors 13A to 13F, the injection amounts of all the injectors 13A to 13F Are substantially the same, and the fluctuation amount of the engine speed of each of the cylinders 2A to 2F is also substantially the same. However, if some of the codes stored in the storage unit 20a are incorrect, the injection amount of the injector with the incorrect code becomes an injection amount that deviates from the injection amount of the other injectors. The fluctuation amount of the engine speed of the cylinders of the cylinders is different from the fluctuation amount of the engine speed of the other cylinders. For example, when the code of the fourth injector 13D stored in the storage unit 20a is an incorrect code, as shown in FIG. 4, the engine rotation in the substantially mountain-shaped region indicated by the broken line indicated by the reference C4 'of the fourth cylinder 2D The fluctuation amount of the number is greatly different from the fluctuation amount of the engine speed of the other cylinders. Therefore, it is possible to determine whether or not the code stored in the storage unit 20a is a correct code from the fluctuation amount of the engine speed of each cylinder 2A to 2F (hereinafter referred to as “engine revolution fluctuation amount”).

  Therefore, when the pressure adjustment unit 20d adjusts the pressure in the common rail 12 to the verification pressure, and the control unit 20b performs the fuel injection control using the correction point set for the verification pressure for each of the injectors 13A to 13F, The rotation fluctuation amount calculation unit 20e calculates the engine rotation fluctuation amount for each of the cylinders 2A to 2F using the engine rotation speed detected by the engine rotation speed sensor 31 at regular intervals. In this calculation, for example, for each of the cylinders 2A to 2F, the engine rotation fluctuation amount corresponding to the area of each hatching region C1 to C6 shown in FIG.

  The determination unit 20f will be described. When the fluctuation amount of the engine speed for each of the cylinders 2A to 2F is calculated by the rotation fluctuation amount calculation unit 20e, the determination unit 20f determines whether or not the engine rotation fluctuation amount of the first cylinder 2A is in the range from the threshold value 1L to the threshold value 1H. Whether the engine rotation fluctuation amount of the second cylinder 2B is in the range from the threshold value 2L to the threshold value 2H, whether the engine rotation fluctuation amount of the third cylinder 2C is in the range of the threshold value 3L to the threshold value 3H, engine fluctuation fluctuation of the fourth cylinder 2D Whether the amount is in the range of the threshold 4L to the threshold 4H, whether the engine rotation fluctuation amount of the fifth cylinder 2E is in the range of the threshold 5L to threshold 5H, or the engine rotation fluctuation amount of the sixth cylinder 2F is in the range of threshold 6L to threshold 6H Each is determined whether or not it is within a range. When there is a cylinder whose engine rotation fluctuation amount is not within the threshold range, in the determination unit 20f, the code of the injector stored in the storage unit 20a is an incorrect code (particularly, the verification pressure (correction point setting pressure)). It is determined that each correction point is set to 1). In this case, the determination unit 20f notifies the vehicle driver of the abnormality. The abnormality notification includes, for example, lighting of a warning light of the fuel injection system, display of information indicating an abnormality of the fuel injection system (in particular, an injector and an injector code), and output of sound. On the other hand, when the engine rotation fluctuation amount of all the cylinders 2A to 2F is within the threshold range, the determination unit 20f determines the verification pressure (correction point setting) of the codes of all the injectors 13A to 13F stored in the storage unit 20a. It is determined that each correction point set to (pressure) is correct. When the code verification for all the correction point set pressures is completed and the engine rotation fluctuation amounts of all the cylinders 2A to 2F are within the threshold range for all the correction point set pressures, the determination unit 20f stores the storage unit It is determined that the codes of all the injectors 13A to 13F stored in 20a are correct codes.

  Each threshold value 1L to 6L is a lower limit value of the engine rotation fluctuation amount of each cylinder 2A to 2F. Each threshold value 1H to 6H is an upper limit value of the engine rotation fluctuation amount of each cylinder 2A to 2F. As a method for setting the threshold values 1L to 6L and 1H to 6H, for example, correct codes (each correction point set to each correction point setting pressure) given to each injector 13A to 13F by an actual vehicle experiment are used. Then, the energization time of each injector 13A to 13F is corrected, fuel is injected from the injector 13A to 13F according to each energization time, the engine rotation fluctuation amount of each cylinder 2A to 2F is calculated in accordance with that, and each cylinder 2A to 2F is calculated. The minimum amount and the maximum amount of the engine rotation fluctuation amount of 2F are acquired, and the threshold values 1L to 6L and 1H to 6H are set from the minimum amount and the maximum amount. It is preferable to set the thresholds 1L to 6L and 1H to 6H after performing the actual vehicle experiment many times and collecting a lot of data. The threshold values 1L to 6L and 1H to 6H may be the same value for all the cylinders 2A to 2F, or may be different values depending on the cylinders 2A to 2F. Since the positional relationship between the cylinders 2A to 2F and the engine speed sensor 31 for obtaining the engine rotation fluctuation is different, the engine rotation is performed even if the work contributing to the engine rotation is equally performed in the cylinders 2A to 2F. The engine speed fluctuation amount acquired from the engine speed detected by the number sensor 31 is different. Therefore, in consideration of the positional relationship between the cylinders 2A to 2F and the engine speed sensor 31, the threshold values 1L to 6L and 1H to 6H are set to different values according to the cylinders 2A to 2F.

  In addition, while the ignition switch is OFF, any of the six injectors 13A to 13F may be replaced due to a failure or the like, and the code of the injector may be rewritten. However, there is no possibility that the code of the injector is rewritten while the ignition switch is ON. Accordingly, the verification of the injector codes (each correction point set to the correction point setting pressure) is performed once for all the injector codes 13A to 13F from when the ignition switch is turned on until it is turned off. Just do it.

  The operation of the injector code verification by the engine ECU 20 of the common rail fuel injection system 10 configured as described above will be described with reference to the flowcharts of FIGS. FIG. 5 is a flowchart of the injector code verification in the engine ECU 20. FIG. 6 is a flowchart of common rail pressure adjustment in the engine ECU 20.

  The operation of the injector code verification will be described. When the ignition of the vehicle is turned on and the diesel engine 1 is operated, the engine ECU 20 determines whether or not the driving state of the vehicle is a steady operation (S10). The determination of S10 is repeatedly performed until a steady operation is achieved. If it is determined in S10 that the operation is steady, the engine ECU 20 starts the injector code verification. First, the engine ECU 20 selects one correction point setting pressure (verification pressure) from among a plurality of correction point setting pressures stored in the storage unit 20a (S11).

  The engine ECU 20 controls the supply pump 11 to adjust until the common rail pressure reaches the verification pressure, and adjusts the common rail pressure to the verification pressure (S12). The operation of adjusting the common rail pressure will be described in detail later.

  When the common rail pressure is adjusted to the verification pressure, the engine ECU 20 acquires the target injection amount of the master injector according to the current operating state of the vehicle, and energizes the master injector for injecting the target injection amount of fuel at the verification pressure. Is acquired (S13). Further, the engine ECU 20 extracts, for each of the injectors 13A to 13F, each correction point set to the calibration pressure correction point setting pressure stored in the storage unit 20a, and uses the extracted correction point to energize the injector. Time is calculated (S13). Here, since the common rail pressure is forcibly adjusted to the verification pressure, the common rail pressure and the correction point set pressure coincide with each other, and the energization time of the injectors 13A to 13F is corrected only by each correction point for one correction point set pressure. it can.

  Then, the engine ECU 20 sequentially supplies current to the injectors 13A to 13F during the energization time of the injectors 13A to 13F in accordance with the injection timing of the injectors 13A to 13F (S13). In response to each energization, the injectors 13A to 13F are sequentially opened to inject fuel sequentially into the cylinders 2A to 2F. The engine speed fluctuates due to the reciprocating motion of the piston 3 in each of the cylinders 2A to 2F according to this. The engine ECU 20 calculates the engine rotational fluctuation amount of each of the cylinders 2A to 2F using the engine rotational speed detected at regular intervals by the engine rotational speed sensor 31 (S14).

  The engine ECU 20 determines whether or not the engine rotation fluctuation amount is larger than the threshold values 1L to 6L and smaller than the threshold values 1H to 6H for each of the cylinders 2A to 2F (S15). If it is determined in S15 that there is a cylinder having an engine rotation fluctuation amount that is not within the lower and upper threshold ranges among the engine rotation fluctuation amounts of the six cylinders 2A to 2F, the engine ECU 20 stores the cylinder in the storage unit 20a. It is determined that the injector code of that cylinder (in particular, each correction point set to the verification pressure (correction point setting pressure)) is abnormal, and an abnormality notification is sent to the vehicle driver (S16). In this case, for example, when the injector is replaced, the code assigned to the injector is not written in the engine ECU 20, so that the normal code of the injector is not stored in the storage unit 20a. Become. On the other hand, when it is determined in S15 that the engine rotation fluctuation amounts of all the cylinders 2A to 2F are within the lower and upper threshold ranges, this verification pressure of all the injectors 13A to 13F stored in the storage unit 20a. The code for (correction point set pressure) is normal.

  The engine ECU 20 determines whether or not all the verification pressures have been verified by using all the correction point set pressures stored in the storage unit 20a as verification pressures (S17). If it is determined in S17 that the verification for all verification pressures has not been completed, the engine ECU 20 returns to S11, selects a verification pressure from the correction point setting pressures that have not been selected, and repeats the above processing. Do. If it is determined in S17 that the verification has been completed for all verification pressures, the engine ECU 20 determines that the verification target verification pressure (correction point setting pressure) code is normal for all verification pressures in S15. Therefore, it is determined that the codes of all the injectors 13A to 13F stored in the storage unit 20a are normal (S18).

  The operation of common rail pressure adjustment will be described. If the verification pressure is selected in S21 when it is determined that the operation is steady in S20 as in the above operation, the engine ECU 20 subtracts the current common rail pressure detected by the common rail pressure sensor 30 from the verification pressure, and the pressure It is determined whether or not the difference is larger than the threshold value AL and smaller than the threshold value AH (S22). If it is determined in S22 that the pressure difference is equal to or less than the threshold value AL or greater than or equal to the threshold value AH, the engine ECU 20 returns to the determination in S20. In this case, if the common rail pressure is adjusted to the selected verification pressure, the exhaust gas cleanliness and the like are affected, so the common rail pressure is not adjusted and the verification is not performed.

  When it is determined in S22 that the pressure difference is larger than the threshold value AL and smaller than the threshold value AH, the engine ECU 20 starts common rail pressure adjustment for adjusting the common rail pressure to the verification pressure (S23). The engine ECU 20 calculates the absolute value of the pressure difference between the verification pressure and the current common rail pressure detected by the common rail pressure sensor 30, and determines whether or not the absolute value of the pressure difference is smaller than the allowable pressure change amount ( S24). When it is determined in S24 that the absolute value of the pressure difference is smaller than the allowable pressure change amount, the engine ECU 20 completes the adjustment of the common rail pressure because the calibration of the common rail pressure has been completed (S25).

  If it is determined in S24 that the absolute value of the pressure difference is greater than or equal to the allowable pressure change amount, the engine ECU 20 determines whether or not the verification pressure is greater than the current common rail pressure detected by the common rail pressure sensor 30 (S26). If it is determined in S26 that the verification pressure is larger than the current common rail pressure, the engine ECU 20 sets the pressure obtained by adding the allowable pressure change amount to the previous target common rail pressure as the current target common rail pressure, and the pressure in the common rail 12 is the current pressure. The supply pump 11 is controlled to achieve the target common rail pressure (S27). In accordance with this control, the supply pump 11 pressurizes the fuel so that the pressure in the common rail 12 is increased by the allowable pressure change amount, and the pressure in the common rail 12 is increased by substantially the allowable pressure change amount. On the other hand, if it is determined in S26 that the verification pressure is equal to or lower than the current common rail pressure, the engine ECU 20 sets the pressure obtained by subtracting the allowable pressure change amount from the previous target common rail pressure as the current target common rail pressure, and the pressure in the common rail 12 is The supply pump 11 is controlled so as to be the target common rail pressure this time (S28). In accordance with this control, the supply pump 11 depressurizes the fuel so that the pressure in the common rail 12 is lowered by the allowable pressure change amount, and the pressure in the common rail 12 is reduced by substantially the allowable pressure change amount. As described above, since the pressure in the common rail 12 changes only by the permissible pressure change amount, even if the engine sound is changed by this pressure change, the vehicle driver or the like is not greatly discomforted. When the process of S27 or S28 ends, the engine ECU 20 returns to the determination of S24.

  According to the engine ECU 20 that is the control device of the common rail fuel injection system 10 described above, the injector code written by performing the injector code verification after adjusting the common rail pressure to the correction point setting pressure (verification pressure). It is possible to accurately detect whether each correction point set to each correction point set pressure is correct. Since it is possible to accurately detect whether the correct injector code is written in the engine ECU 20, it is not necessary to change the hardware so that the code of each injector can be automatically written in the engine ECU 20. Incidentally, if the common rail pressure is not matched with the correction point set pressure, correction is performed using correction points set to two set pressures sandwiching the pressure in the common rail. In this case, since the correction is performed with more correction points for the two set pressures, even if some of the correction points are incorrect, the engine rotation fluctuation amount is influenced by the other correct correction points. May fall within the threshold. Therefore, it may not be possible to accurately determine whether each correction point (code) is correct. However, when the common rail pressure is adjusted to the correction point setting pressure, correction is performed using only the correction point set to the one correction point setting pressure. In this case, since correction is performed with a small number of correction points for one correction point set pressure, even if some of the correction points are incorrect, the degree of influence of other correct correction points is small. Therefore, there is little possibility that the engine rotation fluctuation amount falls within the threshold value. Therefore, it can be accurately determined whether or not the correction point (code) is correct.

  Further, according to the engine ECU 20, since the common rail pressure is not adjusted when the difference between the current common rail pressure and the verification pressure is not within the threshold range, the pressure in the common rail 12 is not greatly adjusted. The effect on exhaust gas cleanliness and the like by adjusting the common rail pressure can be suppressed. Further, according to the engine ECU 20, when the common rail pressure is adjusted, the common rail pressure is changed by the allowable pressure change amount, so that the pressure change amount per time in the common rail 12 can be limited, and the engine is operated due to abnormal noise or the like. Discomfort to the person can be reduced.

  As mentioned above, although embodiment of this invention was described, it is implemented in various forms, without being limited to the said embodiment.

  For example, in the above embodiment, as the correction information set for each of the plurality of set pressures according to the injection characteristics unique to the injector, the correction points (relationship between the injection amount and the energization time) respectively set for the plurality of correction point set pressures. However, other correction information such as a correction curve or a correction straight line indicating the relationship between the injection amount set for each correction point set pressure and the energization time may be used. When correction is performed using a correction curve or a correction straight line, higher-precision correction can be performed.

  Further, in the above embodiment, each correction point set for each correction point setting pressure is stored in a code given to each injector, and information stored in this code is written in the engine ECU, and the information on the code is stored in the code. Although it is configured to be stored in the storage unit of the engine ECU, other than the code may be used, for example, each correction point set to each correction point setting pressure is stored in the IC chip memory, and the IC chip memory Use to write to the engine ECU. When an IC chip memory is used, correction information with a larger amount of information can be written.

  In the above embodiment, the pressure adjustment unit determines whether or not the pressure difference between the verification pressure and the current common rail pressure is within the threshold range. If the pressure difference is not within the threshold range, the common rail pressure is not adjusted. Although the configuration is adopted, a configuration in which such a determination or the like is not performed may be employed. For example, when many correction point set pressures are prepared and the pressure difference between the correction point set pressures is small, the difference between the current common rail pressure and the correction point set pressure closest to the common rail pressure is small. There is no need to limit the adjustment of the common rail pressure. At this time, it is preferable to select a correction point setting pressure closest to the current common rail pressure from among a large number of correction point setting pressures to obtain the verification pressure. In this case, since the pressure difference between the verification pressure and the current common rail pressure becomes small, it may not be necessary to change the pressure in the common rail by the allowable pressure change amount.

  DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2A ... 1st cylinder, 2B ... 2nd cylinder, 2C ... 3rd cylinder, 2D ... 4th cylinder, 2E ... 5th cylinder, 2F ... 6th cylinder, 3 ... Piston, 4 ... Crankshaft, DESCRIPTION OF SYMBOLS 5 ... Flywheel, 10 ... Common rail type fuel injection system, 11 ... Supply pump, 12 ... Common rail, 13A ... 1st injector, 13B ... 2nd injector, 13C ... 3rd injector, 13D ... 4th injector, 13E ... 5th Injector, 13F ... Sixth injector, 14 ... Fuel tank, 20 ... Engine ECU, 20a ... Storage unit, 20b ... Control unit, 20c ... Pressure selection unit, 20d ... Pressure adjustment unit, 20e ... Rotation variation calculation unit, 20f ... Determining unit, 30 ... common rail pressure sensor, 31 ... engine speed sensor.

Claims (3)

A control device for a common rail fuel injection system that injects high-pressure fuel in a common rail from an injector provided for each of a plurality of cylinders in an engine,
A storage unit that stores correction information set for each of the plurality of set pressures according to the injection characteristics for each injector;
A pressure selecting unit for selecting a set pressure from the plurality of set pressures;
A pressure adjusting unit that adjusts the pressure in the common rail to the set pressure selected by the pressure selecting unit;
A control unit that performs fuel injection control using the correction information for each injector in a state in which the pressure in the common rail is adjusted by the pressure adjustment unit;
A determination unit that determines whether the correction information is correct when the fuel injection control by the control unit is performed for each injector;
A control device for a common rail fuel injection system. A pressure detector for detecting the pressure in the common rail;
The pressure adjustment unit is a setting in which the pressure in the common rail is selected by the pressure selection unit when the difference between the set pressure selected by the pressure selection unit and the pressure in the common rail detected by the pressure detection unit is within a threshold value. The control device for a common rail fuel injection system according to claim 1, wherein the control device is adjusted to a pressure.   The common rail fuel injection system according to claim 2, wherein the pressure adjusting unit changes the pressure in the common rail by an allowable pressure change amount when adjusting the pressure in the common rail to the set pressure selected by the pressure selecting unit. Control device.

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