JP2010270697A - Fuel injection quantity control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device capable of estimating time degaradation of an injector. <P>SOLUTION: When it is determined that there is a possibility that deterioration of the injector 22 is progressing, fuel injection with respect to one cylinder 11 is halted, and rotation speed correction control (ISC control) with respect to the remaining cylinders 11 to be injected with fuel is carried out. A total value of rotation speed correction values Qisc by the ISC control is estimated that it is an estimated actual fuel injection quantity Qs injected right before the halting with respect to the halted cylinder 11. The halting operation is sequentially carried out with respect to each cylinder 11, a command injection quantity Qfin injected right before halting stored in a storage circuit 40a is compared with the estimated actual fuel injection quantity Qs, and if there is a difference between the command injection quantity Qfin and the estimated actual fuel injection quantity Qs, it is estimated that deterioration of the injector 22 is progressing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection amount control device that is applied to a multi-cylinder internal combustion engine having a plurality of cylinders and controls a fuel injection amount injected into a combustion chamber of each cylinder.

  Conventionally, a so-called common rail fuel injection system is known in which high pressure fuel accumulated in a common rail is injected into each cylinder of a multi-cylinder diesel engine (internal combustion engine). In the fuel injection amount control device applied to this type of common rail fuel injection system, the basic injection amount for generating the driving torque required according to the engine operating state is controlled and various correction controls are performed. In this way, engine noise is reduced and fuel efficiency is improved.

  For example, during idling operation, idling rotational speed correction control (so-called ISC correction control) for maintaining the engine speed at the target rotational speed, or inter-cylinder inequalities correction control (so-called so-called ISC correction control) for smoothing the rotational speed fluctuation for each cylinder. FCCB correction control) is performed. Further, Patent Document 1 discloses a fuel injection amount control device for accurately executing these ISC correction control and FCCB correction control in an 8-cylinder diesel engine.

JP 2005-155601 A

  By the way, in the general fuel injection amount control device, specifically, the final command injection amount to be injected into the combustion chamber of each cylinder is calculated by the above-described various controls, and this command injection amount and the fuel pressure in the common rail are calculated. Based on the above, the energization time for applying the drive voltage to the solenoid valve of the injector is determined. An injector is arranged for each cylinder, and injects fuel into each combustion chamber while a drive voltage is applied to the solenoid valve.

  Then, the fuel injection amount control device controls the actual fuel injection amount injected into each combustion chamber by changing the energization time to change the valve opening time (injection time) of the injector. At this time, the correlation between the energization time and the actual fuel injection amount may vary depending on the mechanical accuracy of the individual injectors, etc., but it is guaranteed by a single injector so that this variation is within a predetermined allowable range. Has been.

  However, when the internal combustion engine is used for a long period of time, the above-mentioned variation may be out of the allowable range due to deterioration over time such as wear of the mechanical sliding portion of the injector or adhesion of foreign matter. In other words, even if the energization time is determined so that the fuel injection amount control device becomes the command injection amount, the actual fuel injection amount injected from the injector is greatly deviated from the final command injection amount. Sometimes.

  Such divergence between the command injection amount and the actual fuel injection amount not only causes an increase in engine noise and a deterioration in fuel consumption, but can also generate a drive torque required according to the operating state of the engine. It causes the problem of disappearing.

  In view of the above points, it is a first object of the present invention to provide a fuel injection amount control device that can estimate that an injector has deteriorated over time.

  It is a second object of the present invention to provide a fuel injection amount control device that can suppress the difference between the command injection amount and the actual fuel injection amount even when the injector is deteriorated over time.

In order to achieve the above object, the invention according to claim 1 is applied to a multi-cylinder internal combustion engine (10) having a plurality of cylinders (11), and at least the rotational speed of the internal combustion engine (10) is a predetermined target. A basic injection amount determining means for determining a basic injection amount (Q) required for generating a driving torque required for the internal combustion engine (10) in an operation state where the engine speed is Nidl; and a plurality of cylinders (11 And an inter-cylinder unequal amount correction means for calculating an inter-cylinder unequal amount correction amount (Qfccb) with respect to the basic injection amount (Q) for each of the plurality of cylinders (11) so as to smooth the rotational speed fluctuation for each). Rotational speed correction means for calculating a rotational speed correction amount (Qisc) for the basic injection amount (Q) uniformly so that the rotational speed of the internal combustion engine (10) becomes the target rotational speed. Equipped, basic injection quantity (Q), unevenness between cylinders Based on the command injection amount (Qfin) calculated from the correction amount (Qfccb) and the rotational speed correction amount (Qisc), a plurality of injectors (22) for injecting fuel to each of the plurality of cylinders (11) are sequentially provided. A fuel injection amount control device for controlling a fuel injection amount injected and supplied to a plurality of cylinders (11) by driving,
Command injection amount storage means (40a) for storing the command injection amount (Qfin) for each of the plurality of cylinders (11), and fuel injection of the injector (22) for one cylinder (11) among the plurality of cylinders (11) Are sequentially stopped, and based on the total value of the rotational speed correction amount (Qisc) for the other cylinders (11) to be fuel-injected, it is estimated that one cylinder (11) that has been stopped is injected immediately before the stop. And a cylinder-by-cylinder injection amount estimating means (S3 to S6, S8) for estimating the actual fuel injection amount (Qs).

  According to this, since the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) is provided, the estimated actual fuel injection amount (Qs) injected immediately before the stop for one cylinder that is stopped is estimated. can do.

  More specifically, when the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) stops the fuel injection of the injector (22) for one cylinder, the rotation speed correction means causes the rotational speed of the internal combustion engine (10) to increase. The rotational speed correction amount (Qisc) for the other cylinder (11) to which fuel is injected is increased so as to achieve the target rotational speed (Nidl).

  At this time, in order to set the rotational speed of the internal combustion engine (10) to the target rotational speed, the total value of the actual fuel injection amount injected into each cylinder (11) is substantially equal before and after one cylinder is deactivated. It becomes. That is, the total value of the rotational speed correction amount (Qisc) for the other cylinders (11) to which fuel is injected is equal to the actual fuel injection amount injected immediately before the stop for one cylinder (11) that is stopped. It becomes almost the same value.

  Therefore, the estimated actual fuel injection amount (Qs) can be estimated based on the total value of the rotational speed correction amount (Qisc) for the other cylinders (11) to which fuel is injected. The injector (22) is deteriorated over time by comparing the estimated actual fuel injection amount (Qs) with the command injection amount for one cylinder (11) immediately before the stop stored in the command injection amount storage means (40a). Can be estimated.

  Further, since one cylinder (11) is sequentially deactivated, any one of the deactivated one cylinder (11) and the other cylinder (11) for fuel injection has deteriorated over time. If the cylinder (11) of the engine is deactivated, there is a divergence between the total value of the rotational speed correction amount (Qisc) and the command injection amount for one cylinder (11) immediately before deactivation, so the entire internal combustion engine (10) It can be estimated that any one of the injectors (22) is deteriorated with time.

  That is, it is possible to provide a fuel injection amount control device that can estimate that the injector has deteriorated over time.

  According to a second aspect of the present invention, in the fuel injection amount control device of the first aspect, the inter-cylinder inequality correction amount (Qfccb) is equal to or greater than a predetermined reference inter-cylinder inequality correction amount (Qfccb). Deterioration determining means (S1) for determining that there is a possibility that the injector (22) is being deteriorated, and the cylinder-by-cylinder injection amount estimating means (S3 to S6, S8) determines deterioration progress. When the means (S1) determines that the deterioration of the injector (22) may be progressing, the estimated actual fuel injection amount (Qs) is estimated.

  According to this, since the deterioration progress determining means (S1) is provided, it can be suppressed that the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) unnecessarily estimate the estimated actual fuel injection amount (Qs).

  As in the third aspect of the invention, in the fuel injection amount control device according to the first or second aspect, specifically, the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) includes other cylinders (11 ) May be the estimated actual fuel injection amount (Qs).

  According to a fourth aspect of the present invention, in the fuel injection amount control device according to any one of the first to third aspects, immediately before a stop for one cylinder (11) stored in the command injection amount storage means (40a). Learning injection amount determination means (S7) that uses a value obtained by subtracting the estimated actual fuel injection amount (Qs) from the command injection amount (Qfin) as the learning injection amount (Qg), and a learning injection amount (Qfin) Learning injection amount correcting means (S9) for adding Qg).

  According to this, since the learning injection amount determining means (S7) is provided, the difference (deviation) between the command injection amount (Qfin) and the actual fuel injection amount can be quantitatively determined as the learning injection amount (Qg). . Then, the learning injection amount correcting means (S9) adds the learning injection amount (Qg) to the basic injection amount (Q), so that the difference between the command injection amount (Qfin) and the actual fuel injection amount can be suppressed.

  That is, it is possible to provide a fuel injection amount control device that can suppress the difference between the command injection amount (Qfin) and the actual fuel injection amount even when the injector (22) is deteriorated with time.

  According to a fifth aspect of the present invention, in the fuel injection amount control device according to any one of the first to fourth aspects, the injector (22) is provided for a plurality of cylinders (11) in a predetermined injection order. The cylinder (11) to be injected next after the injector (22) injects into the predetermined cylinder (11) and the injection amount estimation means (S3 to S6, S8) for each cylinder are injected into the predetermined cylinder. The cylinder (11) to be deactivated after the cylinder (11) is deactivated is different.

  According to this, it is avoided that the order of the cylinders (11) to be stopped by the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) coincides with the order of the cylinders (11) to inject fuel. It is possible to prevent the internal combustion engine (10) from stopping when the injection amount estimation means (S3 to S6, S8) estimates the estimated actual fuel injection amount (Qs).

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is an overall configuration diagram of a common rail fuel injection system according to an embodiment. It is a mimetic diagram explaining the cylinder arrangement of the diesel engine in one embodiment. It is a flowchart which shows the fuel injection amount learning control in one Embodiment. It is a block diagram which shows the learning execution conditions in one Embodiment. It is a time chart which shows the change of the learning state flag in one embodiment. (A) is explanatory drawing which shows the command injection quantity just before performing fuel injection quantity learning control in one Embodiment, (b) is explanatory drawing which shows the command injection quantity after a pause driving | operation in one Embodiment. . It is a block diagram which shows the learning stop conditions in one Embodiment.

  1-7 demonstrates one Embodiment of this invention. FIG. 1 is an overall configuration diagram of a common rail fuel injection system according to a vehicle diesel engine 10 (internal combustion engine) to which a fuel injection amount control device of the present invention is applied. In the present embodiment, a four-cylinder type having four cylinders 11 is employed as the diesel engine 10.

  A piston 12 that reciprocates in the cylinder 11 is disposed in each cylinder 11 of the diesel engine 10, and a combustion chamber that burns fuel such as light oil on the top surface side of the piston 12 in the inner space of each cylinder 11. 13 is formed. The reciprocating motion of the piston 12 is output as the rotational motion of the crankshaft 15 via the connecting rod 14. In FIG. 1, for clarity of illustration, only one cylinder is shown and the other cylinders are omitted.

  Next, a fuel supply system for supplying fuel into the combustion chamber 13 of each cylinder 11 in the common rail fuel injection system of the present embodiment will be described. In this common rail fuel injection system, as a fuel supply system, a common rail 21 that stores high pressure fuel, an injector 22 that injects high pressure fuel stored in the common rail 21 into each combustion chamber 13, and a supply pump 23 that supplies high pressure fuel to the common rail 21. A fuel tank 24 for storing low-pressure fuel is provided.

  The common rail 21 is a livestock pressure unit that holds and stores the high-pressure fuel supplied from the supply pump 23 at the target rail pressure Pfin. The target rail pressure Pfin is determined by an electronic control unit (hereinafter referred to as ECU) 40, which will be described later, so that the fuel injection pressure from the injector 22 becomes an optimum pressure according to the operating state of the diesel engine 10. .

  Furthermore, a pressure limiter 21a is attached to the common rail 21 to open the fuel pressure in the common rail 21 when the fuel pressure in the common rail 21 exceeds a predetermined upper limit value. The fuel that has flowed out of the pressure limiter 21a is returned to the fuel tank 24 through the fuel pipe 21b.

  The injector 22 is a fuel injection unit that injects and supplies high-pressure fuel stored in the common rail 21 into each combustion chamber 13 of the diesel engine 10. The injector 22 includes a fuel injection nozzle 22a that injects high-pressure fuel into each combustion chamber 13, an electromagnetic valve 22b that opens and closes the fuel injection nozzle, and the like.

  The high-pressure fuel in the common rail 21 is supplied to the fuel injection nozzle 22a via the high-pressure pipe 21c. Of the fuel supplied from the common rail 21, surplus fuel that is not injected from the injector 22 is returned to the fuel tank 24 via the fuel pipe 22c. The operation of the injector 22 is controlled by a drive signal output from the ECU 40.

  Specifically, a drive signal output from the ECU 40 is input to a drive circuit unit (hereinafter referred to as EDU) 41, and the EDU 41 supplies a drive voltage to the electromagnetic valve 22b of the injector 22 according to the input drive signal. Apply. The energization time during which the drive voltage is applied to the electromagnetic valve 22b is the valve opening time (injection time) of the injector 22, and the fuel pressure in the common rail 21 causes the valve 22 to open from the injector 22 into each combustion chamber 13. The fuel injection amount to be injected is determined.

  That is, the ECU 40 controls the fuel injection amount and the injection timing injected into each combustion chamber 13 by changing the length and timing of the valve opening time. In FIG. 1, only one injector 22 is shown for clarification, but in the four-cylinder type diesel engine 10, one for each of the cylinder heads of the four cylinders 11, a total of 4 Two injectors 22 are arranged.

  The supply pump 23 is a fuel pumping means that sucks in the low pressure fuel stored in the fuel tank 24 and pumps the high pressure fuel into the common rail 21. Specifically, the supply pump 23 includes a feed pump unit 23 a that is a low-pressure pump unit that pumps fuel from the fuel tank 24, and a high-pressure pump unit 23 b that further pressurizes the fuel discharged from the feed pump unit 23 a and pumps the fuel to the common rail 21. The intake metering valve 23c for adjusting the flow rate of the fuel supplied from the feed pump unit 23a to the high-pressure pump unit 23b is provided.

  The feed pump unit 23a pumps low-pressure fuel from the fuel tank 24 via the suction pipe 24a connected to the suction side, and supplies it to the suction metering valve 23c side. In the present embodiment, a trochoid pump that operates by being connected to a cam shaft 23d of a high-pressure pump unit 23b described later is employed as the feed pump unit 23a. In addition, a filter 24b that filters the fuel sucked from the fuel tank 24 and removes foreign matters is disposed in the suction pipe 24a.

  The intake metering valve 23c is a linear solenoid type electromagnetic valve configured to be able to continuously change the fuel passage area by adjusting the valve opening. The operation of the intake metering valve 23c is controlled by a control current output from the ECU 40. Specifically, the ECU 40 controls the valve opening degree of the intake metering valve 23c so that the high-pressure pump unit 23b can pump the necessary discharge amount to the common rail 21.

  The high-pressure pump unit 23b includes a cam shaft 23d that is rotated by the diesel engine 10, and a plunger that is a displacement member that is reciprocally displaced inside the cylinder by the driving force transmitted from the cam shaft 23d. In the high-pressure pump portion 23b of the present embodiment, two plungers are provided facing the radial direction of the cam shaft 23d, and the two plungers are alternately operated to perform fuel suction and pressure feeding. A tandem configuration is adopted.

  The fuel pressurized by the high-pressure pump unit 23b is supplied to the common rail 21 via the supply pipe 23e. Further, the supply pump 23 has a high pressure from the return valve 23f, which is a fuel pressure regulating valve that adjusts the fuel pressure downstream of the feed pump unit 23a to a predetermined value by a mechanical mechanism, and the common rail 21 (supply pipe 23e) side. It has a delivery valve 23g, which is a check valve that prevents the fuel from flowing back to the pump portion 23b, and the like.

  Next, in the common rail fuel injection system, an intake / exhaust system that sucks air into the combustion chamber 13 of each cylinder 11 and exhausts fuel gas (exhaust gas) from the combustion chamber 13 will be described. In the common rail fuel injection system of the present embodiment, as an intake / exhaust system, an intake pipe 31 that guides the intake outside air (intake) into each combustion chamber 13 and an exhaust that exhausts combustion gas (exhaust) burned in the combustion chamber 1. A pipe 32, a turbocharger 33 that pressurizes the intake air sucked into the combustion chamber 13, and an EGR passage 34 that circulates the exhaust gas to the intake pipe 31 side are provided.

  In the middle of the intake air flow in the intake pipe 31, an electric throttle valve (not shown), which is an intake throttle valve for adjusting the intake passage area and adjusting the amount of intake air supplied into each combustion chamber 13, is arranged. ing. The operation of the throttle valve is controlled by a control signal output from the ECU 40.

  The turbocharger 33 includes a compressor 33a disposed in the intake pipe 31, an exhaust turbine 33b disposed in the exhaust pipe 32 and connected to the compressor 33a via a turbine shaft, and the like. . Then, by rotating the exhaust turbine 33b with the fluid energy of the exhaust, the compressor 33a is rotationally driven to compress the intake air introduced into the intake pipe 31.

  Further, an intercooler 35 that cools air that has been compressed by the compressor 33a and heated at a high temperature with the outside air is disposed downstream of the intake air flow of the compressor 33a of the turbocharger 33 in the intake pipe 31. Yes. Further, an oxidation catalyst 36 for purifying the exhaust gas by accelerating the oxidation reaction of HC and CO in the exhaust gas is disposed on the exhaust pipe 32 downstream of the exhaust turbine 33b of the turbocharger 33 in the exhaust pipe 32. ing.

  The EGR passage 34 is a passage that branches the flow of exhaust from the upstream side of the exhaust turbine 33 b in the exhaust pipe 32 and circulates and joins the branched exhaust to the intake air on the downstream side of the intercooler 35 in the intake pipe 31. This reduces the oxygen concentration in the intake air and suppresses the generation of nitrogen oxides. Further, an EGR valve 34 a that controls the amount of exhaust gas by adjusting the opening of the EGR passage 34 is disposed on the intake pipe 31 side of the EGR passage 34. The operation of the EGR valve 34a is controlled by a control signal output from the ECU 40.

  Next, an electric control system in the common rail fuel injection system of this embodiment will be described. The ECU 40 is a well-known microcomputer including a CPU that performs control processing and arithmetic processing, a storage circuit 40a such as a ROM and RAM that stores programs and data, an output circuit that outputs control signals to various control devices, and various sensors. An input circuit to which a detection signal is input, a power supply circuit, and the like are included.

  Specifically, the output side of the ECU 40 is connected to the EDU 41 that applies the drive voltage to the injector 22 described above, the intake metering valve 23c of the supply pump 23, the EGR valve 34a, and the like. To control. Accordingly, among the ECU 40, in particular, the configuration (including hardware and software) for controlling the operation of the injector 22 and the EDU 41 constitute the fuel injection amount control device of the present embodiment.

  On the other hand, on the input side of the ECU 40, detection signals from a crank position sensor 42, a cylinder discrimination sensor 44, and the like made of a magnet pickup are input. Specifically, the crank position sensor 42 is a rotation speed detection unit that generates a rotation pulse signal according to the distance from a plurality of teeth formed on the outer periphery of a pulse rotor 43 that is connected to the crankshaft and rotates. . The ECU 40 detects the engine speed Ne from the pulse interval of the rotation pulse signal.

  The cylinder discriminating sensor 44 is a cylinder discriminating unit that generates a cylinder discriminating pulse signal according to the distance from a plurality of teeth formed on the outer periphery of a pulse rotor 45 that is connected to the camshaft 18 and rotates. The camshaft has a cam that rotates eccentrically and drives the intake valve 16 and the exhaust valve 17 of each cylinder 11, and is a rotating shaft that rotates once while the crankshaft rotates twice. Further, the tooth portion of the pulse rotor 45 is provided at a portion corresponding to a predetermined position of the piston 12 of each cylinder 11.

  Further, on the input side of the ECU 40, an accelerator opening sensor 46 that detects the accelerator opening Accp, a common rail pressure sensor 47 that detects the fuel pressure Npc in the common rail 21, and an intake flow upstream side of the compressor 33a in the intake pipe 31. An intake air amount sensor 48 that measures the intake air amount, an intake air pressure sensor 49 that is disposed downstream of the intercooler 35 in the intake pipe 31 to detect the intake air pressure, and cooling water that cools the diesel engine 10. Sensor groups such as a coolant temperature sensor (not shown) for detecting the temperature Tw and a throttle position sensor (not shown) for detecting the valve opening of the throttle valve are connected.

  Next, the basic operation of the common rail fuel injection system of this embodiment will be described. When the ignition switch (not shown) is turned on (turned on) after the diesel engine 10 is started by a starter (not shown), the ECU 40 executes the control program stored in the storage circuit 40a. Thus, the ECU 40 determines the final command injection amount Qfin, target rail pressure Pfin, and injection timing that are supplied from each injector 22 into the combustion chamber 13 of each cylinder 11 according to the operating state of the diesel engine 10. Etc.

  Specifically, the ECU 40 refers to a control map stored in advance in the storage circuit 40a on the basis of the engine speed Ne and the accelerator opening signal Accp, and generates a driving torque required for the diesel engine 10. The basic injection amount Q of each injector 22 is determined. Therefore, the ECU 40 according to the present embodiment includes function realizing means as basic injection amount determining means. Further, the ECU 40 determines a value obtained by adding various correction amounts Qfccb, Qisc, etc., which will be described later, to the basic injection amount Q as a final command injection amount Qfin for each injector 22.

  Further, the ECU 40 determines a fuel injection pressure, that is, a target rail pressure Pfin that is a target fuel pressure in the common rail 21 based on the command injection amount Qfin and the engine speed Ne. Further, the ECU 40 determines a control current to the intake metering valve 23c of the supply pump 23 by a feedback control method or the like so that the fuel pressure Npc in the common rail 21 becomes the target rail pressure Pfin. As a result, the required amount of fuel is pumped into the common rail 21 from the high-pressure pump portion 23 b of the supply pump 23.

  Further, the ECU 40 refers to the control map stored in advance in the storage circuit 40a based on the command injection amount Qfin, the engine speed Ne, the fuel pressure Npc in the common rail 21, the coolant temperature Tw, etc. A command injection period corresponding to the energization time for applying the drive voltage to the electromagnetic valve 22b of each injector 22 is determined.

  At this time, the ECU 40 of the present embodiment performs so-called multi-injection control in which fuel is injected into each cylinder 11 of the diesel engine 10 in a plurality of times. More specifically, before the main injection, the injector 22 is driven a plurality of times during the compression stroke and the expansion stroke in one cycle (intake stroke-compression stroke-explosion stroke-exhaust stroke) of one cylinder 11. A plurality of pilot injections are performed at the same time, and a plurality of after injections are performed after the main injection. Thereby, the exhaust reduction and noise reduction of the diesel engine 10 are aimed at.

  Next, correction control for the basic injection amount Q executed by the ECU 40 will be described. The correction control described below is executed during an idling operation that is an operation state in which the rotation speed of the diesel engine 10 is maintained so as to be a predetermined target rotation speed Nidl.

  First, the ECU 40 detects the rotational speed fluctuation of each cylinder 11 during the explosion stroke based on the fluctuation of the time interval of the rotation pulse signal output from the crank position sensor 42 and the cylinder discrimination pulse signal output from the cylinder discrimination sensor 44. . For each cylinder 11, the rotational speed fluctuation between the cylinders 11 is smoothed according to the difference between the detected value of the rotational speed fluctuation of each cylinder 11 and the average value of the rotational speed fluctuations of all the cylinders 11. An inter-cylinder uneven amount correction amount Qfccb is calculated. This control is called inter-cylinder non-uniform amount correction control or FCCB control.

  Further, the ECU 40 uniformly calculates the rotational speed correction amount Qisc for all the cylinders 11 so that the engine rotational speed Ne becomes the target rotational speed Nidl during idling operation. This control is called rotational speed correction control or ISC control. Therefore, the ECU 40 according to the present embodiment includes function realizing means as inter-cylinder inequalities correction means and rotation speed correction means.

  In the common rail fuel injection system of this embodiment, the injectors 22 of each cylinder 11 are sequentially driven so that fuel of the command injection amount Qfin determined by the above basic operation is supplied to each cylinder 11. More specifically, among the cylinders 11 arranged in series as shown in FIG. 2, fuel is injected and supplied in the order of # 1 → # 3 → # 4 → # 2. The stroke-explosion stroke-exhaust stroke is repeated. As a result, the piston 12 of each cylinder 11 reciprocates, and a rotational motion serving as vehicle running power is output from the crankshaft 15.

  Further, the ECU 40 of the present embodiment estimates that the injector 22 has deteriorated with time when there is a possibility that the injector 22 has deteriorated as when the diesel engine 10 has been operated for a long time. Furthermore, fuel injection amount learning control is performed to prevent the command injection amount Qfin and the fuel injection amount actually injected into each combustion chamber 13 from deviating due to the deterioration of the injector 22 over time.

  This fuel injection amount learning control will be described with reference to the flowchart of FIG. The fuel injection amount learning control routine shown in FIG. 3 is a subroutine executed at predetermined time intervals with respect to the main routine executed during normal operation after the ignition switch is turned on.

  First, in step S1 of FIG. 3, it is determined whether or not to execute fuel injection amount learning control. Specifically, when the learning execution condition shown in FIG. 4 is satisfied, the fuel injection amount learning control is executed. When the learning execution condition is not satisfied, the processing returns to the main routine without executing the fuel injection amount learning control.

  The learning execution condition shown in FIG. 4 is (A) the idling operation time: the idling operation time is, for example, among the detection values of the various sensor groups that detect the operation state of the diesel engine 10 described above. The determination can be made based on values such as the fuel pressure Npc in the common rail 21, the engine speed Ne, and the accelerator opening degree Accp.

  (B) Engine stable state: The engine stable state means that the absolute value of the value obtained by subtracting the engine rotational speed Ne from the target rotational speed Nidl during idling operation is within a predetermined value. It is that you are. Therefore, the determination can be made based on the value of the engine speed Ne.

  (C) Satisfies at least one of the learning state flag being 0 and the inter-cylinder uneven amount correction amount Qfccb for each cylinder 11 being equal to or greater than a predetermined value: the learning state flag As shown in FIG. 5, the control flag indicates that the fuel injection amount learning control is not completed (= 0), is being executed (= 1), and is completed (= 2). It is stored in the memory circuit 40a.

  And when satisfy | filling all the conditions of said (A)-(C), deterioration of the injector 22 may be advancing and a learning state flag is set to 1, and it progresses to step S2. Therefore, the ECU 40 of the present embodiment includes a function realization means as a deterioration progress determination means, and specifically, the control step S1 constitutes a deterioration progress determination means.

  In step S2, the ECU 40 stores the command injection amount Qfin for each combustion chamber 13 in the storage circuit 40a immediately before executing the fuel injection amount learning control. Therefore, the ECU 40 of the present embodiment includes a function realizing unit as a command injection amount storage unit, and specifically, a storage circuit 40a such as a RAM constitutes the command injection amount storage unit.

  Next, the process proceeds to step S3, the fuel injection from the injector 22 to one cylinder 11 out of the four cylinders 11 is stopped, and the fuel injection from the injector 22 is performed to the remaining three cylinders 11 to generate a diesel engine. A pause operation for operating 10 is executed. In the next step S4, the rotational speed correction control (ISC control) described above is executed, and the rotational speed correction amount Qisc is uniformly added to the command injection amounts Qfin of the three cylinders 11 to be injected with fuel.

  In step S5, it is determined whether or not the engine is in a stable state. If it is determined that the engine is not in a stable state, the process returns to step S4, and rotational speed correction control (ISC control) is performed again. Execute. On the other hand, if it is determined in step S5 that the engine is in a stable state, in step S6, the estimated actual fuel injection amount Qs that is estimated to have been injected immediately before the stop for one cylinder that has been stopped. Is estimated.

Details of the estimation of the estimated actual fuel injection amount Qs executed in step S6 will be described with reference to FIG. First, FIG. 6A is an explanatory diagram showing the command injection amount Qfin for each cylinder 11 immediately before performing the fuel injection amount learning control. For example, the command injection amount Qfin for the cylinder 11 of # 1 is obtained by adding the total value 1 mm ³ / st of the inter-cylinder non-uniformity correction amount Qfccb and the rotational speed correction amount Qisc to the basic injection amount Q of 10 mm ³ / st. , and it has a total of 11mm ³ / st.

Similarly, the command injection amount Qfin for each cylinder 11 of # 2 to # 4 are each ^{10mm 3 / st, 12mm 3 /} st, and has a 8 mm ³ / st. The command injection amount Qfin for each of the cylinders # 1 to # 4 is a value stored in the storage circuit 40a of the ECU 40 in the above-described control step S2.

Next, in FIG. 6B, for example, after stopping the fuel injection from the injector 22 for the cylinder 11 of # 1 in the control step S3, it is determined in the control step S5 that the engine is in a stable state. It is a figure which shows the command injection quantity Qfin with respect to each cylinder 11 at the time of being performed. For the cylinder 11 of # 1, since the fuel injection from the injector 22 is stopped, the command injection amount Qfin is 0 mm ³ / st.

On the other hand, the command injection amount Qfin for each cylinder 11 of # 2 to # 4 is uniformly added by ³ mm ³ / st by the rotational speed correction control (ISC control) in the control step S4. That is, in the control step S3, when the fuel injection from the injector 22 to the # 1 cylinder 11 is stopped, the fuel injection is performed so that the rotational speed of the diesel engine 10 becomes the target rotational speed Nidl. The rotational speed correction amount Qisc for each cylinder 11 is increased.

At this time, in order to set the rotational speed of the diesel engine 10 to a predetermined target rotational speed Nidl, the total value of the actual fuel injection amount injected into each cylinder 11 is substantially equal before and after one cylinder is deactivated. Become. Accordingly, the total rotational speed correction amount Qisc for the cylinders # 2 to # 4 to be injected with fuel (in this embodiment, 3 mm ³ / st × 3 cylinders = 9 mm ³ / st) is at rest # This is substantially equal to the actual fuel injection amount injected immediately before the stop of one cylinder 11.

Therefore, in the control step S6 of the present embodiment, the total value (9 mm ³ / st) of the rotational speed correction amount Qisc for the cylinders # 2 to # 4 to be injected with fuel is paused for the cylinder 11 for # 1. The estimated actual fuel injection amount Qs is assumed to have been injected immediately before. Then, comparing the estimated actual fuel injection amount Qs (9mm ³ / st) and the command injection amount Qfin for # 1 cylinder 11 resting immediately before which is stored in the memory circuit 40a the ECU40 (11mm ³ / st).

  At this time, if the estimated actual fuel injection amount Qs and the command injection amount Qfin for the # 1 cylinder 11 just before the stop match, it can be estimated that the injector 22 for the # 1 cylinder 11 has not deteriorated over time. On the other hand, if the estimated actual fuel injection amount Qs is different from the command injection amount Qfin for the # 1 cylinder 11 just before the stop, it can be estimated that the injector 22 for the # 1 cylinder 11 has deteriorated over time.

In other words, in the example shown in FIG. 6, the # 22 cylinder 11 injector 22 has deteriorated with time, and the ECU 40 injects and supplies 11 mm ³ / st (command injection amount Qfin) of fuel to the combustion chamber 13. Thus, even if the drive signal is output to the EDU 41, it is estimated that only 9 mm ³ / st (estimated actual fuel injection amount Qs) is actually supplied to the combustion chamber 13.

Next, it progresses to step S7 and the learning injection quantity Qg is determined. Specifically, for one cylinder 11 that has been deactivated in step S3, a learning injection amount is obtained by subtracting the estimated actual fuel injection amount Qs from the command injection amount Qfin for one cylinder 11 immediately before deactivation stored in the storage circuit 40a. Qg. In the example shown in FIG. 6, 2mm ³ / st learning injection quantity of 9 mm ³ / st estimate is the actual fuel injection amount Qs of 11 mm ³ / st a command injection amount Qfin is obtained by subtracting for resting just before the # 1 cylinder 11 Qg.

  In the next step S8, it is determined whether or not the learning injection amount Qg is determined for all the cylinders 11 of # 1 to # 4, and it is determined that the learning injection amount Qg is not determined for all the cylinders 11. Returning to step S3, the next cylinder 11 is deactivated, and the estimation of the estimated actual fuel injection amount Qs and the determination of the learned injection amount Qg for the deactivated cylinder 11 are sequentially executed.

  In the present embodiment, the order of cylinders to be deactivated is # 1 → # 2 → # 4 → # 3. Accordingly, the cylinder 11 to be injected next after the ECU 40 injects fuel into the injector 22 of the predetermined cylinder 11 and the cylinder 11 to be stopped next after the control step S3 stops the predetermined cylinder 11 are different. Yes.

  On the other hand, if it is determined in step S8 that the learning injection amount Qg has been determined for all the cylinders 11, the learning state flag is set to 2 and the process proceeds to step S9. In step S9, when the learning state flag is 2 in the main routine, the control routine is changed so that the learning injection amount Qs is added to the command injection amount Qfin of each cylinder 11, and the learning injection is changed. The amount Qg is reflected.

  Therefore, the ECU 40 of the present embodiment includes a function realizing unit as a cylinder-by-cylinder injection amount estimating unit. Specifically, the control steps S3 to S6 and S8 constitute a cylinder-by-cylinder injection amount estimating unit. Further, the ECU 40 includes a function realizing unit as a learning injection amount determining unit. Specifically, the control step S7 constitutes a learning injection amount determining unit. Further, the ECU 40 includes a function realizing unit as a learning injection amount correcting unit. Specifically, the control step S9 constitutes a learning injection amount correcting unit.

  Note that while the fuel injection amount learning control routine is being executed, that is, when the learning state flag is 1, a learning control stop routine is also executed separately from the fuel injection amount learning control routine. In this learning control stop routine, when the condition shown in FIG. 7 is satisfied, the fuel injection amount learning control is immediately stopped and the main routine is executed, and the learning state flag is set to zero.

  The conditions shown in FIG. 7 are: (D) When the fluctuation amount per unit time of the fuel pressure Npc in the common rail 21 exceeds a predetermined amount, (E) The fluctuation amount per unit time of the engine speed Ne. Is greater than a predetermined amount, (F) when a predetermined time has elapsed since the execution of the fuel injection amount learning control routine, and at least one of them is satisfied.

  Since the fuel injection amount control device of this embodiment operates as described above, it can be estimated that the injector has deteriorated over time by the control steps S3 to S6 and S8 as the cylinder injection amount estimation means. That is, it is possible to provide a fuel injection amount control device that can estimate that the injector has deteriorated over time.

  Further, since one cylinder 11 is sequentially deactivated, any cylinder 11 is deactivated regardless of which one of the deactivated cylinders 11 and the other cylinders 11 for fuel injection have deteriorated over time. If this is the case, there is a difference between the total value of the rotational speed correction amount Qisc and the command injection amount Qfin for one cylinder 11 immediately before the stop, so that deterioration of the injector 22 over time occurs in any diesel engine 10 as a whole. Can be estimated.

  Further, the control step S7 as the learning injection amount determining means can quantitatively determine the difference (deviation) between the command injection amount Qfin and the actual fuel injection amount as the learning injection amount Qg. Since the learning injection amount Qg is added to the command injection amount Qfin by the control step S9 as the learning injection amount correcting means, the difference between the command injection amount Qfin and the actual fuel injection amount can be suppressed. That is, it is possible to provide a fuel injection amount control device that can suppress the difference between the command injection amount Qfin and the actual fuel injection amount even if the injector 22 is deteriorated with time.

  Further, when the learning state flag is 2, the control routine is changed so as to add the learning injection amount Qs to the command injection amount Qfin of each cylinder 11 to reflect the learning injection amount Qg. After execution of the fuel injection amount learning control, the diesel engine 10 can be quickly brought into an engine stable state to reduce engine noise and improve fuel efficiency.

  Further, when all of the above conditions (A) to (C) are satisfied, it is possible to avoid the fuel injection amount control device unnecessarily estimating the estimated actual fuel injection amount Qs and determining the learning injection amount Qg. . Further, since the order of the cylinders 11 to be deactivated by the control steps S3 to S6 and S8 as the cylinder injection amount estimation means is avoided from matching the injection order of the cylinders 11 to be injected, the estimated actual fuel When estimating the injection amount Qs, it can be avoided that the diesel engine 10 stops.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows.

  (1) In the above-described embodiment, the example in which the fuel injection amount control device is applied to the in-line four-cylinder diesel engine 10 has been described. However, the application of the present invention is not limited to this. For example, a multi-cylinder engine such as a 6-cylinder type or an 8-cylinder type is applicable. Further, the cylinder arrangement is not limited to the in-line type, and can be applied to a V type, a horizontally opposed type, and the like.

  (2) In the above embodiment, the basic injection amount Q is determined by determining the operating state of the diesel engine 10 based on the engine speed Ne and the accelerator opening signal Accp, but the basic injection amount Q is determined. However, the present invention is not limited to this.

  For example, the fuel pressure Npc in the common rail 21, the cooling water temperature Tw, and other various sensors for detecting operating conditions (intake air amount sensor 48, intake air pressure sensor 49, fuel temperature sensor for detecting fuel temperature, atmospheric pressure for detecting atmospheric pressure) The basic injection amount Q may be determined using detection signals from an atmospheric pressure sensor, an outside air temperature sensor that detects outside air temperature, a throttle position sensor, and the like. The same applies to the command injection amount Qfin, the target rail pressure Pfin, the injection timing, and the like.

  (3) In the above-described embodiment, the learning execution condition (A) is determined based on values such as the fuel pressure Npc in the common rail 21, the engine speed Ne, and the accelerator opening degree Accp as the idling operation time. Although described, the determination of being in idling operation is not limited to this.

For example, if a position sensor (switch) that detects the shift position is provided, and the shift position is “N” neutral and “P” parking after the ignition switch is turned on, it is determined that the vehicle is idling. May be. Furthermore, when the detected value of the vehicle speed sensor for detecting the vehicle traveling speed is 0 km / h, it may be determined that the vehicle is idling. (4) In the above-described embodiment, the cylinder-by-cylinder injection amount estimating means is In the control step S6, the total value of the rotational speed correction amount Qisc for the cylinder 11 to be injected with fuel is the estimated actual fuel injection amount Qs of the cylinder 11 that has been deactivated. A value obtained by performing a correction such as multiplying the value by a correction coefficient may be used as the estimated actual fuel injection amount Qs.

  (5) In the above-described embodiment, when there is a difference between the command injection amount Qfin and the estimated actual fuel injection amount Qs for the cylinder 11 immediately before deactivation, it is assumed that the injector 22 of the cylinder 11 has deteriorated over time. Although the learning injection amount Qg is determined, warning means may be provided to warn the user when there is a difference between the command injection amount Qfin for the cylinder 11 immediately before the stop and the estimated actual fuel injection amount Qs. . For example, a warning lamp as a warning means may be turned on to prompt the user to replace the injector 22.

  (6) In the above-described embodiment, the learning stop conditions (D) to (E) are adopted, but the learning stop condition is not limited to this. For example, the learning stop condition may be satisfied when the shift position is other than “N” neutral and “P” parking, or when the detection value of the vehicle speed sensor is greater than 0 km / h.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Cylinder 22 Injector 40 ECU
40a memory circuit

Claims (5)

Applied to a multi-cylinder internal combustion engine (10) having a plurality of cylinders (11);
The basic injection amount (Q) required to generate the drive torque required for the internal combustion engine (10) at least in an operating state where the rotational speed of the internal combustion engine (10) is a predetermined target rotational speed (Nidl). Basic injection amount determining means for determining
An inter-cylinder non-uniformity correction amount (Qfccb) with respect to the basic injection amount (Q) is calculated for each of the plurality of cylinders (11) so as to smooth the rotational speed fluctuation for each of the plurality of cylinders (11). Inter-cylinder inequalities correction means;
Rotational speed correction for calculating a rotational speed correction amount (Qisc) for the basic injection amount (Q) uniformly in the plurality of cylinders (11) so that the rotational speed of the internal combustion engine (10) becomes the target rotational speed. Means and
Based on the command injection amount (Qfin) calculated from the basic injection amount (Q), the inter-cylinder non-uniformity correction amount (Qfccb), and the rotation speed correction amount (Qisc), the plurality of cylinders (11). A fuel injection amount control device for controlling a fuel injection amount to be injected and supplied to the plurality of cylinders (11) by sequentially driving a plurality of injectors (22) for injecting fuel to each of them,
Command injection amount storage means (40a) for storing the command injection amount (Qfin) for each of the plurality of cylinders (11);
Of the plurality of cylinders (11), the fuel injection of the injector (22) for one cylinder (11) is stopped sequentially, and the total rotational speed correction amount (Qisc) for the other cylinders (11) to be fuel-injected A cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) for estimating an estimated actual fuel injection amount (Qs) injected immediately before the stop to the one cylinder (11) that is stopped based on the value; A fuel injection amount control apparatus comprising: Deterioration progress determining means (S1) for determining that there is a possibility that the deterioration of the injector (22) is progressing when the inter-cylinder uneven amount correction amount (Qfccb) is not less than a predetermined value. With
The cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) determines the estimated actual value when the deterioration progress determining means (S1) determines that the deterioration of the injector (22) may be progressing. The fuel injection amount control device according to claim 1, wherein the fuel injection amount (Qs) is estimated.   The cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) uses the total value of the rotational speed correction amount (Qisc) for the other cylinders (11) as the estimated actual fuel injection amount (Qs). The fuel injection amount control device according to claim 1 or 2. A value obtained by subtracting the estimated actual fuel injection amount (Qs) from the command injection amount (Qfin) immediately before deactivation for the one cylinder (11) stored in the command injection amount storage means (40a) is used as a learning injection amount ( Learning injection amount determining means (S7) as Qg),
The fuel injection amount according to any one of claims 1 to 3, further comprising learning injection amount correction means (S9) for adding the learning injection amount (Qg) to the command injection amount (Qfin). Control device. The injector (22) is configured to inject fuel into the plurality of cylinders (11) in a predetermined injection order.
The cylinder (11) to be injected next after the injector (22) injects into the predetermined cylinder (11), and the cylinder-by-cylinder injection amount estimation means (S3 to S6, S8) pause the predetermined cylinder (11). The fuel injection amount control device according to any one of claims 1 to 4, wherein the cylinder (11) to be stopped next is different.

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