JP5229965B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device for injecting fuel into a cylinder of an internal combustion engine, and more particularly, to a fuel injection control for executing a required fuel injection control with high accuracy by correcting the fuel injection amount. It relates to the device.

  Conventionally, a pressure accumulation type fuel injection device has been used as a device for injecting fuel into a cylinder of a diesel engine as one aspect of an internal combustion engine. This accumulator type fuel injection device is provided with a common rail to which a plurality of fuel injection valves are connected and high pressure fuel is stored, and energization control of the fuel injection valves is performed in a state where the high pressure fuel is supplied to each fuel injection valve. By doing so, precise injection of fuel is performed.

  In such an accumulator type fuel injection device, if the fuel used is different, there is a risk that emission may deteriorate due to differences in fuel properties such as purity and density, and vehicle drivability may deteriorate. A fuel injection device for an internal combustion engine that determines the property of the fuel that is in control and controls the fuel injection amount to a target value is disclosed.

  Specifically, at least two fuel injections of the previous injection and the subsequent injection are performed from one fuel injection valve during one cycle of the engine, and after the previous injection is performed until the subsequent injection is performed. In the injection control device for an internal combustion engine in which the amount of change of the injection amount of the subsequent injection with respect to the target value changes according to the interval time, the above-mentioned of the subsequent injection when the reference fuel is used in the predetermined engine operating state The reference interval time at which the fluctuation amount becomes the reference value is stored in advance, and the fluctuation amount of the subsequent injection is the reference value when the engine operating state becomes the predetermined engine operating state during engine operation. And the propagation speed of the pressure pulsation in the fuel used at that time is calculated from the interval time ratio between the reference interval time and the calculated interval time. The fuel injection system of an internal combustion engine so as to correct the control constants of the engine based on the fuel property that is estimated by estimating a fuel property from the speed has been proposed (see Patent Document 1).

JP 2005-76562 A

  The fuel injection device for an internal combustion engine disclosed in Patent Document 1 causes pressure pulsation in the fuel by the previous injection, and fluctuations in the injection amount of the subsequent injection obtained based on the relationship between the engine speed (angular velocity) and the total injection amount. The propagation speed of the pressure pulsation in the fuel is calculated based on the interval time at which the quantity becomes the reference value, and the engine control constant is corrected based on the fuel property estimated from the propagation speed of the pressure pulsation.

  Here, the angular velocity of the internal combustion engine when a certain fuel injection is performed differs depending on the position of the piston in the cylinder when the fuel injection is performed. That is, if the position of the piston in the cylinder when the fuel injection is performed is different, the time from the fuel injection to the ignition of the fuel is different, so the combustibility in the cylinder changes. Therefore, even when the same amount of fuel is injected, the angular velocity of the internal combustion engine varies depending on the position of the piston in the cylinder. Therefore, the angular velocity of the internal combustion engine used when obtaining the variation amount of the injection amount of the subsequent injection in Patent Document 1 is not limited to the influence of the total injection amount inherently due to the propagation speed of the pressure pulsation. It is also influenced by the position of the piston at the time of injection or subsequent fuel injection.

  However, in Patent Document 1, it is assumed that the engine speed (angular speed) affects only the total injection quantity, and the injection quantity of the subsequent injection is determined based on the relationship between the engine speed (angular speed) and the total injection quantity. The amount of fluctuation is obtained. Therefore, the variation amount of the injection amount of the subsequent injection is different from the actual variation amount, and the fuel property estimated from the ratio between the interval time at which the variation amount becomes the reference value and the reference interval time is different from the actual fuel property. Therefore, the engine control constant may not be corrected accurately.

  Therefore, the inventor of the present invention has made diligent efforts to correct the fuel injection amount according to the fuel property estimated based on the angular velocity fluctuation of the internal combustion engine when the two injections are executed. The present invention has been completed by finding that the above-mentioned problem can be solved by performing correction in consideration of the relationship between the injection interval and the angular velocity fluctuation of the internal combustion engine. That is, the present invention eliminates the influence of the angular velocity fluctuation of the internal combustion engine due to the difference in the fuel injection timing during the cycle of the internal combustion engine, thereby more accurately grasping the properties of the fuel to be used and It is an object of the present invention to provide a fuel injection control device capable of performing correction with high accuracy.

  According to the present invention, it is used for controlling an accumulator fuel injection device that injects fuel accumulated in a common rail into a cylinder of an internal combustion engine by means of a fuel injection valve, and calculates a target fuel injection amount to each cylinder of the internal combustion engine. Non-injection state detection for detecting a non-injection state of an internal combustion engine in a fuel injection control device comprising: a target injection amount calculation unit; and a fuel injection valve control unit that performs drive control of a fuel injection valve based on a target fuel injection amount , An angular velocity detection unit that detects the angular velocity of the internal combustion engine, and two fixed-time injections that are performed at a predetermined injection interval when the non-injection state of the internal combustion engine is detected. And estimating the fuel property of the fuel from the pressure pulsation period of the fuel determined based on the angular velocity fluctuation of each internal combustion engine or the correlation value of the angular speed fluctuation when the two constant-time injections are executed a plurality of times, A property correction coefficient calculation unit for calculating a property correction coefficient for correcting the target fuel injection amount or the fuel injection valve drive signal based on the property, and the target fuel injection amount or the fuel injection valve drive signal by the property correction coefficient. A fuel injection amount correction unit that performs correction, and a coefficient correction unit that corrects the property correction coefficient based on the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation that is stored in advance based only on the difference in injection interval. Is provided to solve the above-described problems.

  Further, when configuring the fuel injection control device of the present invention, the coefficient correction unit is configured to execute two constant injections, each of which is stored in advance and is injected at a predetermined injection amount, a plurality of times at different injection intervals. It is preferable to correct the property correction coefficient based on the relationship between the injection interval and the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation.

  Further, in configuring the fuel injection control device of the present invention, the property correction coefficient calculation unit fixes the second injection timing in the cycle of the internal combustion engine when the non-injection state of the internal combustion engine is detected, By varying the first injection timing, the two-time injection execution control unit that executes the two-time injection multiple times while changing the injection interval, and the two-time constant-time injection multiple times By comparing the angular velocity fluctuation of the internal combustion engine with the angular velocity fluctuation when the constant time injection is not executed, the relationship between the injection interval of the two constant time injections and the angular velocity fluctuation of the internal combustion engine is obtained, and the injection interval and the angular velocity fluctuation or A pressure pulsation cycle calculation unit that calculates the cycle of fuel pressure pulsation based on the correlation value of the angular velocity fluctuation, and a property correction unit that estimates the fuel property according to the period of fuel pressure pulsation and based on the fuel property Preferably contains a correction coefficient calculating unit for calculating a.

  Further, in configuring the fuel injection control device of the present invention, the pressure pulsation cycle calculation unit calculates the cycle of the fuel pressure pulsation by converting the angular velocity fluctuation into the fluctuation of the fuel injection amount by two fixed-time injections. Is preferred.

  In configuring the fuel injection control device of the present invention, it is preferable that the fixed-time injection is a micro injection.

  Further, in configuring the fuel injection control device of the present invention, the coefficient correction unit fixes the second injection timing stored in the cycle of the internal combustion engine, while differentiating the first injection timing. Based on the relationship between the injection interval of the two quantitative injections and the angular velocity fluctuation of the internal combustion engine when the two quantitative injections are performed multiple times while changing the injection interval, the angular velocity fluctuation and pressure pulsation of the pressure pulsation cycle calculation unit are determined. It is preferable to correct the property correction coefficient by correcting at least one of the period or the fuel injection amount.

  Further, in configuring the fuel injection control device of the present invention, the fuel injection control device executes one micro injection a plurality of times while changing the injection time when the non-injection state of the internal combustion engine is detected. The injection time when the angular velocity fluctuation of the internal combustion engine when the minute number of micro injections is executed becomes a preset reference fluctuation number is obtained, and the target fuel injection amount or fuel is calculated based on the ratio of the injection time and the reference injection time An individual difference correction coefficient calculation unit for calculating an individual difference correction coefficient for correcting the drive signal of the injection valve is provided, and the fuel injection amount correction unit further includes a target fuel injection amount or a fuel injection valve drive signal according to the individual difference correction coefficient. It is preferable to perform the correction.

  Further, in configuring the fuel injection control device of the present invention, it is preferable that the property correction coefficient calculation unit obtains the property correction coefficient by converting the fuel property into a correlation value of the fuel temperature.

  Another aspect of the present invention is used in an accumulator fuel injection device that injects fuel accumulated in a common rail into a cylinder of an internal combustion engine by a fuel injection valve, and sets a target fuel injection amount to each cylinder of the internal combustion engine. A non-injection for detecting a non-injection state of an internal combustion engine in a fuel injection control device comprising a target injection amount calculation unit for calculating and a fuel injection valve control unit for performing drive control of a fuel injection valve based on the target fuel injection amount A state detection unit, an angular velocity detection unit that detects the angular velocity of the internal combustion engine, and a single micro injection execution that executes a single micro injection a plurality of times while changing the injection time when a non-injection state of the internal combustion engine is detected Based on the control unit and the injection time when the angular velocity fluctuation of the internal combustion engine when a single minute injection is executed reaches a preset reference fluctuation number, and based on the ratio of the injection time and the reference injection time Eye A first correction coefficient calculation unit that calculates an individual difference correction coefficient for correcting the fuel injection amount or the drive signal of the fuel injection valve; and when a non-injection state of the internal combustion engine is detected, at a predetermined injection interval Two fixed time injections are performed twice, while the second injection time in the cycle of the internal combustion engine is fixed, while the first injection time is varied to change the injection interval multiple times. By comparing the angular velocity fluctuation of each internal combustion engine when the time constant microinjection execution control unit is executed a plurality of times of the constant time microinjection with the angular speed fluctuation when the constant time microinjection is not executed, Find the relationship between the injection interval of two constant-time micro-injections and the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation, and calculate the fuel pressure pulsation cycle based on the relationship between the injection interval and the angular velocity fluctuation or the correlation value Pressure A pulsation cycle calculation unit and a fuel correction factor for correcting the target fuel injection amount or fuel injection valve drive signal based on the fuel property, while estimating the fuel property according to the fuel pressure pulsation cycle A second correction coefficient calculation unit that performs two fixed minute injections each of which is stored in advance at a predetermined injection amount, while fixing the second injection timing in the cycle of the internal combustion engine, Pressure pulsation cycle calculation based on the relationship between the injection interval of two quantitative micro-injections and the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation when the injection interval is changed multiple times with different injection timings A coefficient correction unit that corrects at least one of the angular velocity fluctuation or its correlation value or pressure pulsation period in the unit, and the target fuel injection amount or fuel by the individual difference correction coefficient and the property correction coefficient A fuel injection control device comprising: a fuel injection amount correction unit that corrects a drive signal of an injection valve.

  According to another aspect of the present invention, there is provided a fuel injection control method for correcting a fuel injection amount in an accumulator fuel injection device that injects fuel accumulated in a common rail into a cylinder of an internal combustion engine by a fuel injection valve. When no non-injection state is detected, each of the two fixed-time injections performed at a predetermined injection interval is executed a plurality of times while changing the injection interval, and the two fixed-time injections are executed a plurality of times. When calculating the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular speed fluctuation, and executing the two fixed-time injections obtained based on the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation only by the difference in the injection interval stored in advance. Of the fuel pressure pulsation obtained based on the value obtained by subtracting the angular velocity fluctuation or its correlation value corresponding to the injection interval from the angular velocity fluctuation or its correlation value Depending estimate the fuel property of fuel is a fuel injection control method characterized by correcting the drive signal of the target fuel injection amount or the fuel injection valve based on the fuel property.

  According to the fuel injection control device and the fuel injection control method of the present invention, the fuel injection amount using the fuel property estimated on the basis of the angular velocity fluctuation of the internal combustion engine or the correlation value when the two fixed-time injections are executed. In performing the correction, the fuel property is estimated based on the angular velocity fluctuation that excludes the influence of the angular velocity fluctuation of the internal combustion engine due to the difference in the position of the piston in the cylinder at the time of fuel injection due to the difference between the two fuel injection intervals. The Therefore, the fuel property is accurately estimated, and the correction of the fuel injection amount is accurately executed based on the fuel property.

It is a figure for demonstrating the structural example of a pressure accumulation type fuel-injection apparatus. It is a block diagram for demonstrating the structural example of the fuel-injection control apparatus of this embodiment. It is a figure for demonstrating the calculation process of the individual difference correction coefficient calculating part. It is a figure for demonstrating the calculation process of a property correction coefficient calculating part. It is a figure for demonstrating the calculation process of a property correction coefficient calculating part. It is a figure for demonstrating the calculation process of a coefficient correction | amendment part. It is a flow for demonstrating the fuel-injection control method of this embodiment. It is a flow of calculation of an individual difference correction coefficient. It is a flow of calculation of a property correction coefficient. It is a flow for demonstrating the method which correct | amends by converting a fuel property into the correlation value of fuel temperature.

  Embodiments relating to a fuel injection control device of the present invention will be specifically described below with reference to the drawings. However, the following embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, what attached | subjected the same code | symbol in each figure has shown the same member, and description is abbreviate | omitted suitably.

1. FIG. 1 shows a schematic configuration of an accumulator fuel injection apparatus 50 provided with a fuel injection control apparatus 70 according to an embodiment of the present invention. An accumulator fuel injection apparatus 50 shown in FIG. 1 is an accumulator fuel injection apparatus that injects fuel into a cylinder of a diesel engine as an internal combustion engine 40, and includes a fuel tank 1, a low pressure pump 2, and a high pressure pump 5. The main rail 10, the fuel injection valve 13, the fuel injection control device 70, and the like are provided as main elements.

  In the internal combustion engine 40, the piston 42 reciprocates in the cylinder 41 as the crankshaft 43 rotates, and diesel fuel is injected into the cylinder 41 in the compression stroke, causing an explosion in the cylinder 41 and pushing down the piston 42. Then, the crankshaft 43 is driven by being further rotated. The internal combustion engine 40 is provided with a crank angle sensor 45 for detecting a crank angle that is a rotational phase of the crankshaft 43.

  In the accumulator fuel injection device 50, the low pressure pump 2 and the high pressure pump 5 are connected by a low pressure fuel passage 18, and the high pressure pump 5 and the common rail 10, and the common rail 10 and the fuel injection valve 13 are connected by high pressure fuel passages 37 and 39, respectively. ing. Further, return passages 30 a to 30 c for returning leaked fuel or return fuel to the fuel tank 1 are connected to the high-pressure pump 5, the common rail 10, the fuel injection valve 13, and the like.

  The low pressure pump 2 sucks up the low pressure fuel in the fuel tank 1 and supplies the low pressure fuel to the high pressure pump 5 through the low pressure fuel passage 18. As the low-pressure pump 2, an electric low-pressure pump that is driven by energization, a gear pump that is driven by the power of an internal combustion engine, or the like is used.

  The high-pressure pump 5 pressurizes the low-pressure fuel sent by the low-pressure pump 2 and sends the high-pressure fuel to the common rail 10 via the high-pressure fuel passage 37. The low-pressure fuel passage 18 upstream of the pressurizing chamber 5a of the high-pressure pump 5 is provided with a flow control valve 8, and the low-pressure fuel supplied to the pressurizing chamber 5a according to the required rail pressure, the required injection amount, etc. The flow rate is adjusted. As the flow control valve 8, for example, an electromagnetic proportional flow control valve in which the stroke amount of the valve body is variable depending on the magnitude of the supplied pulse voltage is used.

  A pressure adjustment valve 14 is connected upstream of the flow control valve 8, and the pressure adjustment valve 14 is further connected to a return passage 30 a that communicates with the fuel tank 1. The pressure regulating valve 14 is an overflow valve that is opened when the difference between the front and rear pressures, that is, the difference between the pressure in the low pressure fuel passage 18 and the pressure in the return passage 30a exceeds a predetermined value. Yes.

  The common rail 10 accumulates high-pressure fuel pumped from the high-pressure pump 5 and supplies the high-pressure fuel to the plurality of fuel injection valves 13 connected via the high-pressure fuel passage 39. A rail pressure sensor 21 and a pressure control valve 12 are attached to the common rail 10. For example, an electromagnetic proportional control valve is used as the pressure control valve 12, the amount of fuel leaked from the common rail 10 to the fuel leak passage 30 b is adjusted, and the rail pressure is adjusted according to the amount of leak.

  The fuel injection valve 13 connected to the common rail 10 includes a nozzle body provided with an injection hole and a nozzle needle that closes the injection hole, and the back pressure acting on the rear end side of the nozzle needle is released to release the injection hole. Is opened, and the high-pressure fuel supplied from the common rail 10 is injected into the cylinder of the internal combustion engine 40. As the fuel injection valve 13, for example, an electromagnetic control type fuel injection valve provided with a solenoid valve as a back pressure control unit, or an electrostrictive type fuel injection valve provided with a piezo element as a back pressure control unit is used.

  The accumulator fuel injector 50 is provided with a fuel temperature sensor (not shown) for detecting the fuel temperature. Although the arrangement position of the fuel temperature sensor is not particularly limited, for example, it is arranged in a fuel passage provided in the high-pressure pump.

  The accumulator fuel injection device 50 of the present embodiment described so far is only one configuration example of a conventionally known accumulator fuel injection device, and the accumulator fuel injection device provided with the fuel injection control device of the present invention is other than this. It may be configured as follows.

2. Fuel Injection Control Device FIG. 2 is a functional block diagram showing the configuration of the fuel injection control device 70 of this embodiment. The fuel injection control device 70 is configured around a microcomputer having a known configuration, and includes a target injection amount calculation unit 71, a non-injection state detection unit 72, an angular velocity detection unit 73, and a fuel temperature detection unit 74. An individual difference correction coefficient calculation unit 80, a property correction coefficient calculation unit 90, a coefficient correction unit 75, a fuel injection amount correction unit 77, and a fuel injection valve control unit 79. The individual difference correction coefficient calculation unit 80 includes a single minute injection execution control unit 81 and a first correction coefficient calculation unit 83. The property correction coefficient calculation unit 90 includes a two-time fixed time minute injection execution control unit 91, a pressure pulsation cycle calculation unit 93, and a second correction coefficient calculation unit 95. Specifically, each of these units is realized by executing a program by a microcomputer.

  Further, the fuel injection control device 70 includes a storage unit (RAM: Random Access Memory) (not shown). In this storage unit, information calculated or detected in each unit and information of sensors provided in the accumulator 50 or the internal combustion engine 40 are stored, and the stored information is read by each unit as necessary. It is.

(1) Target injection amount calculation unit The target injection amount calculation unit 71 calculates a target fuel injection amount Qtgt of fuel to be injected into the cylinder of the internal combustion engine 40 based on the rotational speed Ne of the internal combustion engine 40, the accelerator operation amount Acc, and the like. calculate. Specifically, in the target injection amount calculation unit 71, in addition to the rotational speed Ne of the internal combustion engine 40 and the accelerator operation amount Acc, the state of the catalyst and particulate filter used for exhaust gas purification, the fuel temperature, and the like are considered. The target pilot injection amount, the target main injection amount, and the target post injection amount are each calculated.

(2) Non-injection state detection unit The non-injection state detection unit 72 reads the target fuel injection amount Qtgt calculated by the target injection amount calculation unit 71 and the accelerator operation amount Acc, and detects the non-injection state of the internal combustion engine 40. . Specifically, the non-injection state detection unit 72 of the fuel injection control device 70 according to the present embodiment performs an overrun in which the fuel is brought into the non-injection state when the driver releases the accelerator from a traveling state at a high speed or medium speed. Detect state. If there is a non-injection state of the internal combustion engine 40 other than the overrun state, the state may be detected. When the non-injection state is detected, the non-injection state detection unit 72 transmits a signal to the individual difference correction coefficient calculation unit 80 and the property correction coefficient calculation unit 90.

(3) Angular velocity detection unit and fuel temperature detection unit The angular velocity detection unit 73 continuously reads the sensor value of the crank angle sensor 45 every unit time and detects the angular velocity ω of the rotational displacement of the crankshaft 43 per unit time. . The fuel temperature detection unit 74 continuously reads the sensor value of the fuel temperature sensor and detects the fuel temperature.

(4) Individual Difference Correction Coefficient Calculation Unit The individual difference correction coefficient calculation unit 80 calculates the target fuel injection amount Qtgt and the actual fuel injection amount Qact due to variations in individual differences due to processing accuracy for each fuel injection valve 13 or deterioration over time. An individual difference correction coefficient α which is a correction coefficient for correcting the deviation is obtained. This variation in individual difference occurs due to the influence of the size of the injection hole of the fuel injection valve 13, the stroke amount of the valve body, the slidability, the degree of clogging of the injection hole, and the like. In the fuel injection control device 70 of the present embodiment, the injection time ETa1 in which a predetermined reference micro-injection amount Qzfc1 is injected is based on the transition of the angular velocity ω of the internal combustion engine 40 (hereinafter referred to as “angular velocity variation Ω”). The individual difference correction coefficient α for correcting the fuel injection amount based on the ratio between the reference injection time ETa0 set as the injection time during which the reference minute injection amount Qzfc1 is injected and the determined injection time ETa1 is obtained. It is configured.

A method for obtaining the individual difference correction coefficient α will be specifically described with reference to FIGS.
The single minute injection execution control unit 81 that constitutes the individual difference correction coefficient calculation unit 80 applies to the fuel injection valve 13 to be corrected when the non-injection state of the internal combustion engine 40 is detected by the non-injection state detection unit 72. Thus, an instruction is transmitted to the fuel injection valve control unit 79 so as to perform a control for executing a single micro injection a plurality of times while changing the injection time ETa during one cycle. This micro injection controls the current or voltage supplied to the fuel injection valve 13 so that the reference micro injection amount Qzfc1, for example, 1 cc, is injected so as not to greatly affect the driving force of the internal combustion engine 40. . When one micro injection is executed, the angular velocity fluctuation Ω of the internal combustion engine 40 increases from the compression stroke to the expansion process in the cylinder into which the fuel is injected (see FIG. 3A).

  In addition, the first correction coefficient calculation unit 83 constituting the individual difference correction coefficient calculation unit 80 is performed each time a single micro injection is executed from the fuel injection valve 13 to be corrected by the single micro injection execution control unit 81. The signal is received, and the angular velocity fluctuation Ωzfc1 when the minute injection is performed is compared with the angular velocity fluctuation Ωzfc0 when the minute injection is not performed to obtain the difference ΔΩzfc1 of the angular velocity fluctuation. When this single micro injection is executed a plurality of times while changing the injection time ETa, the relationship between the difference ΔΩzfc1 between the increased angular velocity fluctuation Ωzfc1 and the angular velocity fluctuation Ωzfc0 in other cylinders and the injection time ETa is obtained ( (See FIGS. 3 (a) and 3 (b)). The angular velocity fluctuation Ω is compared with the angular velocity fluctuation Ωzfc1 from the compression stroke to the expansion stroke in the cylinder provided with the fuel injection valve 13 to be corrected, and the angular velocity fluctuation Ωzfc0 from the compression stroke to the expansion stroke in the other cylinders. This is done by comparing. By performing such a comparison, the difference ΔΩzfc1 of the angular velocity fluctuation is obtained in a short time, and the individual difference correction coefficient α is calculated quickly when the internal combustion engine 40 is in the non-injection state.

  The individual difference correction coefficient calculation unit 80 can refer to data (see FIG. 3C) indicating the relationship between the fuel injection amount Qact stored in advance in the fuel injection amount control device 70 and the difference ΔΩzfc of the angular velocity fluctuation. Thus, the first correction coefficient calculation unit 83 obtains the injection time ETa1 of one minute injection when the difference ΔΩzfc1 of the angular velocity fluctuation becomes the reference value ΔΩ0. This reference value ΔΩ0 is obtained and stored in advance through experiments or the like as a value of the difference in angular velocity fluctuation that occurs when fuel of the reference minute injection amount Qzfc1 is injected. Then, the obtained injection time ETa1 is compared with a reference injection time ETa0 determined as an injection time at which the difference of the angular velocity fluctuation becomes a reference value ΔΩ0 in the setting of the accumulator fuel injection device 50 at the time of shipment, etc. The ratio of the injection time ETa1 to ETa0 (ETa1 / ETa0) is set as an individual difference correction coefficient α.

  The individual difference correction coefficient α obtained in this way is multiplied by the target fuel injection amount Qtgt, the control instruction value to the fuel injection valve 13 or the arithmetic expression of the target injection amount in the fuel injection amount correction unit 77, so that The fuel injection amount Qact is increased or decreased. As a result, the difference between the target fuel injection amount Qtgt and the actual fuel injection amount Qact due to processing accuracy, deterioration with time, and the like is eliminated.

(5) Property correction coefficient calculation unit The property correction coefficient calculation unit 90 assumes that the fuel property ρact represented by the density, viscosity, etc. of the currently used fuel sets the calculation formula for the target fuel injection amount Qtgt. A property correction coefficient β, which is a correction coefficient for correcting a deviation between the target fuel injection amount Qtgt and the actual fuel injection amount Qact due to the difference from the fuel property ρ0 of the reference fuel that has been set, is obtained. An error in fuel pressure (rail pressure) occurs due to differences in fuel properties such as density and viscosity of the fuel used, and appears as variations in the fuel injection amount. In the fuel injection control device 70 of the present embodiment, two constant-time micro injections performed at a predetermined injection interval ΔT are executed a plurality of times to obtain the relationship between the injection interval ΔT and the angular velocity fluctuation Ω of the internal combustion engine 40, and Based on the relationship, the fuel property is estimated by calculating the pressure pulsation period Cpr of the current fuel. The property correction coefficient β is obtained based on, for example, the estimated fuel property ρact and the fuel property ρ0 of the reference fuel.

The method for obtaining the property correction coefficient β will be specifically described with reference to FIGS. 4 (a) to 4 (d) and FIGS. 5 (a) to 5 (b).
The two-time fixed-time microinjection execution control unit 91 constituting the property correction coefficient calculation unit 90 is connected to any one of the fuel injection valves 13 when the non-injection state of the internal combustion engine 40 is detected by the non-injection state detection unit 72. On the other hand, an instruction is transmitted to the fuel injection valve control unit 79 so as to perform control to execute two fixed time minute injections injected at a predetermined injection interval ΔT in a single cycle a plurality of times while changing the injection interval ΔT. To do. In contrast to the fact that the fuel injection valve 13 for executing the micro injection when determining the individual difference correction coefficient α must be the fuel injection valve to be corrected, it is small for a fixed time twice when determining the property correction coefficient β. The fuel injection valve 13 that executes the injection may be any fuel injection valve.

  The injection interval ΔT of the two fixed-time minute injections can be changed by fixing the second injection timing while making the first injection timing different. For example, the first injection time ETb1 and the second injection time are set so that the injection amount Qzfc2 of the fuel injected by the two fixed-time micro injections does not greatly affect the driving force of the internal combustion engine 40. The current or voltage supplied to the fuel injection valve 13 is controlled so that the injection time ETb2 is both 200 μsec. When the micro injection is performed twice at a constant time, the angular velocity fluctuation Ω of the internal combustion engine 40 increases from the compression stroke to the expansion process in the cylinder in which the fuel is injected (see FIG. 4A).

  Here, the first fixed time minute injection is basically performed in a state where the pressure pulsation in the fuel is small, and in the fuel injection control device 70 of the present embodiment, the fuel injection amount is corrected by the individual difference correction coefficient α. Therefore, the injection amount Qet1 of the first fixed time minute injection becomes a substantially constant value. The value of the injection amount Qet1 is obtained by calculation based on the injection time ETb1. On the other hand, the second fixed-time microinjection is performed in a state where pressure pulsation is generated in the fuel by the first fixed-time microinjection, so the injection amount Qet2 of the second fixed-time microinjection is the fuel pressure (rail The pressure varies depending on the pressure.

  In addition, the pressure pulsation period calculation unit 93 constituting the property correction coefficient calculation unit 90 is executed by the two-time fixed-time micro-injection execution control unit 91 from the fuel injection valve 13 two times in a single cycle. Each time the signal is received, the angular velocity fluctuation Ωzfc2 when the two fixed-time micro-injections are performed is compared with the angular velocity fluctuation Ωzfc0 when the two fixed-time micro-injections are not executed. Obtain the difference ΔΩzfc2 of fluctuation. When the two constant time micro-injections are executed a plurality of times while changing the injection interval ΔT, the relationship between the increased angular velocity fluctuation Ωzfc2 and the difference ΔΩzfc2 of the angular velocity fluctuation Ωzfc0 in other cylinders and the injection interval ΔT is obtained. (See FIGS. 4 (a) and (b)). As in the case of the individual difference correction coefficient calculation unit 80, the angular velocity fluctuation Ω is compared with the angular velocity fluctuation Ωzfc2 from the compression stroke to the expansion stroke in the cylinder provided with the fuel injection valve 13 to be corrected. This is carried out by comparing with the angular velocity fluctuation Ωzfc0 from the compression stroke to the expansion stroke. By performing such a comparison, the difference ΔΩzfc2 in the angular velocity fluctuation can be obtained in a short time, and the calculation of the pressure pulsation cycle Cpr when the internal combustion engine 40 is in the non-injection state, and hence the calculation of the property correction coefficient β, can be performed quickly. Is called.

  The pressure pulsation cycle calculation unit 93 calculates the pressure pulsation cycle Cpr of the fuel used based on the difference ΔΩzfc2 between the plurality of angular velocity fluctuations. Specifically, the property correction coefficient calculation unit 90 refers to data indicating the relationship between the fuel injection amount Qact stored in advance in the fuel injection amount control device 70 and the difference ΔΩzfc in angular velocity fluctuation (see FIG. 4C). 3 (same as (c)). The pressure pulsation cycle calculation unit 93 refers to this data and replaces the relationship between the angular velocity fluctuation difference ΔΩzfc2 and the injection interval ΔT with the relationship between the fuel injection amount Qact and the injection interval ΔT.

  Furthermore, since the difference in the fuel injection amount Qact between the two fixed-time minute injections is due to the difference in the rail pressure (fuel pressure) Prail, the pressure pulsation cycle calculation unit 93 determines that the fuel injection amount Qact and the injection interval ΔT are Is replaced with the relationship between the rail pressure Prail and the injection interval ΔT (see FIG. 4D). Since this injection interval ΔT corresponds to the elapsed time from the first fixed time micro injection, the relationship between the injection interval ΔT and the rail pressure Prail is that a fixed amount of the first fixed time micro injection is performed. It represents the fluctuation of the rail pressure Prail generated by the above, that is, pressure pulsation. Based on the pressure pulsation thus obtained, the pressure pulsation cycle Cpr is obtained.

  At this time, based on the value of the difference ΔΩzfc2 of the plurality of angular velocity fluctuations, the relationship between the injection interval ΔT of the two fixed-time micro injections and the actual fuel injection amount Qact can be obtained in the present embodiment. In the case of the fuel injection control device 70, the fuel injection amount is corrected by the individual difference correction coefficient α, and the relationship between the angular velocity fluctuation Ω of the internal combustion engine and the actual fuel injection amount Qact depends on the currently used fuel. It is because it is grasped. In addition, the actual fuel injection amount Qact can be converted to the rail pressure Prail because the injection time ETb2 of the second fixed time minute injection is constant, and the difference in the actual fuel injection amount Qact is the injection pressure, that is, the rail pressure. This is due to differences in the Prail.

  The property correction coefficient calculation unit 90 correlates the period Cpr of the pressure pulsation, the fuel temperature Tfl, and the fuel property (density) ρ that are generated when the fuel is injected during the injection time ETb1 of the first fixed time fine fuel injection. Data indicating the relationship (see FIG. 5A) is stored. The second correction coefficient calculation unit 95 constituting the property correction coefficient calculation unit 90 refers to this data, and executes the pressure pulsation cycle Cpr obtained by the pressure pulsation cycle calculation unit 93 and the two fixed time micro injections. The fuel property ρact of the used fuel is estimated based on the fuel temperature Tfl at the time.

Then, the second correction coefficient calculation unit 95 calculates the difference between the obtained fuel property ρact of the used fuel and the fuel property ρ0 of the reference fuel assumed when setting the calculation formula of the target fuel injection amount Qtgt. Accordingly, the property correction coefficient β is calculated. In the present embodiment, the fuel property ρact is further converted into a correlation value Tf _ρ of the fuel temperature Tf to obtain the property correction coefficient β. Specifically, in the second correction coefficient calculation unit 95, the correlation between the fuel property (density) ρ0 of the reference fuel and the fuel temperature Tf assumed when setting the calculation formula of the target fuel injection amount Qtgt is shown. The data shown is stored in advance (see FIG. 5B). Second correction coefficient calculation unit 95 refers to this data, the fuel property ρact use fuel obtained is converted to the correlation value Tf _[rho fuel temperature. This correlation value Tf _ρ represents the difference between the fuel property ρ0 of the reference fuel and the fuel property ρact of the fuel used, which was assumed when setting the calculation formula of the target fuel injection amount Qtgt, and the reference temperature Tf0 of the reference fuel. It is replaced with the difference. Then, in the second correction coefficient calculation unit 95, a property correction coefficient β corresponding to the fuel temperature correlation value Tf _ρ is obtained.

  The property correction coefficient β obtained in this way is multiplied by the target fuel injection amount Qtgt or the control instruction value to the fuel injection valve 13 in the fuel injection amount correction unit 77, whereby the actual fuel injection amount Qact is increased or decreased. The As a result, the difference between the target fuel injection amount Qtgt and the actual fuel injection amount Qact due to the difference in the fuel property ρact of the used fuel is eliminated.

(6) Coefficient Correction Unit The coefficient correction unit 75 calculates the pressure pulsation cycle of the property correction coefficient calculation unit 90 based on the angular velocity fluctuation Ω of the internal combustion engine 40 that is stored only in advance and is different only in the injection interval ΔT between the two injections. Correction is performed for at least one of the angular velocity fluctuation Ω, the fuel injection amount Qact, or the pressure pulsation cycle Cpr used in the unit 93. By performing this correction, when the property correction coefficient calculating unit 90 obtains the property correction coefficient β using the angular velocity variation Ω, the angular velocity variation due to the difference in the piston position when two fixed time micro injections are performed. The effect of Ω variation is eliminated.

  In the fuel injection control device 70 of the present embodiment, the two fixed micro-injection intervals ΔT when two fixed micro-injections each injected at a predetermined injection amount are executed a plurality of times while changing the injection interval ΔT, and Data indicating the relationship with the angular velocity fluctuation Ω of the internal combustion engine 40 is obtained and stored in advance by experiments or the like. Hereinafter, a specific example of a method for obtaining in advance the relationship between the injection interval ΔT of the two quantitative micro-injections and the angular velocity fluctuation Ω of the internal combustion engine 40 will be described with reference to FIGS. In the following specific example, the relationship between the injection interval ΔT and the angular velocity fluctuation Ω of the internal combustion engine 40 is replaced with the relationship between the injection interval ΔT and the fuel injection amount Qzfc3.

  In the non-injection state of the internal combustion engine, two quantitative minute injections are executed from the fuel injection valve. When the two fixed minute injections are executed, the angular velocity fluctuation Ω of the internal combustion engine increases from the compression stroke to the expansion step in the cylinder provided with the fuel injection valve (see FIG. 6A). The injection amount in the two quantitative micro injections is set to a certain amount that does not greatly affect the driving force of the internal combustion engine in both the first quantitative micro injection and the second quantitative micro injection. In particular, the injection time of the first quantitative micro-injection is the same as the injection time ETb1 of the first constant-time micro-injection executed by the second fixed-time micro injection execution control unit 91.

  By comparing the angular velocity fluctuation Ωzfc3 when the two quantitative micro-injections are performed with the angular velocity fluctuation Ωzfc0 when the two quantitative micro-injections are not executed, the angular velocity fluctuation difference ΔΩzfc3 is obtained. The comparison of the angular velocity fluctuation Ω is similar to the case of the individual difference correction coefficient calculation unit 80 and the property correction coefficient calculation unit 90 in the compression stroke in the cylinder provided with the fuel injection valve 13 that performs two quantitative micro injections. The angular velocity fluctuation Ωzfc3 from the expansion stroke to the expansion stroke can be compared with the angular velocity fluctuation Ωzfc0 from the compression stroke to the expansion stroke in the other cylinders.

  This two-time quantitative microinjection is performed by changing the injection timing of the first quantitative microinjection while fixing the injection timing of the second quantitative microinjection in one cycle of the cylinder in which fuel injection is performed. The injection interval ΔT is changed and executed a plurality of times. When two quantitative micro-injections are executed a plurality of times while changing the injection interval ΔT, the relationship between the difference ΔΩzfc3 between the increased angular velocity fluctuation Ωzfc3 and the angular velocity fluctuation Ωzfc0 in other cylinders and the injection interval ΔT is obtained ( (See FIGS. 6 (a) and 6 (b)).

  The coefficient correction unit 75 stores data indicating the relationship between the fuel injection amount Qact stored in advance in the fuel injection amount control device 70 and the difference ΔΩzfc in angular velocity fluctuation (see FIG. 6C). (Same as FIG. 4C)) can be referred to, and the relationship between the difference ΔΩzfc3 of the angular velocity fluctuation and the injection interval ΔT of the two quantitative micro-injections is the relationship between the fuel injection amount Qzfc3 and the injection interval ΔT. It is replaced (see FIG. 6 (d)). The coefficient correction unit 75 stores the relationship between the injection interval ΔT between the two fixed minute injections thus obtained in advance and the fuel injection amount Qzfc3.

  Then, the coefficient correction unit 75 calculates the pressure pulsation cycle for the pressure pulsation cycle calculation unit 93 of the property correction coefficient calculation unit 90 based on the relationship between the stored injection interval ΔT and the fuel injection amount Q zfc3. The property correction coefficient β is calculated using a value Qact ′ obtained by subtracting the fuel injection amount Qzfc3 corresponding to the injection interval ΔT from the fuel injection amount Qact of the relationship between the fuel injection amount Qact and the injection interval ΔT used at the time. To send instructions.

  Here, the coefficient correction unit 75 stores data indicating the relationship between the fuel temperature Tf and the fuel property (density) ρ. The coefficient correction unit 75 calculates the coefficient correction unit based on the fuel injection amount Qact obtained by the property correction coefficient calculation unit 90. When subtracting the fuel injection amount Qzfc3 obtained in 75, the value of the fuel injection amount Qzfc3 to be subtracted according to the difference between the reference temperature Tf0 of the reference fuel and the temperature Tf of the used fuel is corrected. .

  As a result, the pressure pulsation cycle Cpr obtained in the property correction coefficient calculation unit 90 is calculated from the difference in angular velocity fluctuation ΔΩzfc2 caused by two constant-time micro-injections from the angular velocity fluctuation Ω caused by the difference in the injection interval ΔT. The influence is eliminated, and it is obtained based on the difference value of the angular velocity fluctuation only due to the difference in the injection pressure (rail pressure) at the second fixed time minute injection. Therefore, the fuel property ρ of the used fuel is accurately estimated, and the fuel injection amount Qact is corrected with accuracy by the difference in the fuel property ρ.

  In the fuel injection amount control device 70 of the present embodiment, the fuel injection amount Qzfc3 corresponding to the injection interval ΔT between the two fixed minute injections is subtracted from the value of the fuel injection amount Qact of the property correction coefficient calculation unit 80. However, the correction target may be other than the fuel injection amount Qact. For example, the correction may be performed by subtracting the difference ΔΩzfc3 of the angular velocity variation corresponding to the injection interval ΔT, which is obtained by the coefficient correction unit 75, from the difference ΔΩzfc2 of the angular velocity variation in the property correction coefficient calculation unit 90. It is also possible to perform correction on the fluctuation of the rail pressure Prail other than the above and the period Cpr of the pressure pulsation.

(7) Fuel Injection Amount Correction Unit The fuel injection amount correction unit 77 uses the individual difference correction coefficient α and the property correction coefficient β calculated by the individual difference correction coefficient calculation unit 80 and the property correction coefficient calculation unit 90 to perform target injection. The target fuel injection amount Qtgt calculated by the amount calculation unit 71 or the calculation formula of the target injection amount is corrected, and the corrected target fuel injection amount Qtgt ′ is calculated.
In the fuel injection control device 70 of the present embodiment, the difference in fuel temperature also causes a difference in fuel viscosity and the fuel pressure is affected. Therefore, not only individual differences and fuel properties but also the predetermined pressure of the accumulator fuel injection device 50 is determined. The target fuel injection amount Qtgt is corrected based on the value of the fuel temperature Tf detected by the fuel temperature sensor provided at the location. Therefore, the fuel injection control device 70 is not a method of performing correction by obtaining the property correction coefficient β itself, but the correlation value Tf _ρ of the fuel temperature Tf obtained in the middle of the calculation is used as the fuel temperature detected by the fuel temperature sensor. It is also possible to correct the target fuel injection amount Qtgt by adding to the value of Tf.

(8) Fuel Injection Valve Control Unit The fuel injection valve control unit 79 reads the rail pressure Prail, and based on the read rail pressure Prail and the corrected target injection amount Qtgt ′ calculated by the fuel injection amount correction unit 77. The fuel injection valve 13 is controlled. Specifically, the fuel injection valve control unit 79 determines the energization timing and energization time for the fuel injection valve 13 and outputs an instruction signal to an actuator that controls the drive of the fuel injection valve 13.

3. Specific Flow of Fuel Injection Control Method Next, the fuel injection amount correction control executed by the fuel injection amount control device 70 of the present embodiment will be described in detail based on the control flows of FIGS.

In FIG. 7, the individual difference correction coefficient α is calculated in step S1 after the start. FIG. 8 shows a flow of calculation of the individual difference correction coefficient α.
In the calculation flow of the individual difference correction coefficient α, first, in step S11, the accelerator operation amount Acc, the engine speed Ne, and the like are read, and then in step S12, the target fuel injection amount Qtgt is calculated.

  Next, in step S13, it is determined whether or not the internal combustion engine is in the non-injection state based on the accelerator operation amount Acc, the target fuel injection amount Qtgt, and the like. If the internal combustion engine is not in the non-injection state, the individual difference correction coefficient α cannot be calculated, and the process returns to step S11. On the other hand, when the internal combustion engine is in the non-injection state, the process proceeds to step S14, the injection time ETa for one minute injection is set to a predetermined value, and then one minute injection is executed in step S15.

  Next, in step S16, the angular velocity fluctuation Ωzfc1 of the internal combustion engine when the single minute injection is executed is detected, and in step S17, the angular speed fluctuation Ωzfc0 of the internal combustion engine when the single minute injection is not executed is detected. Next, in step S18, the difference ΔΩzfc1 between the angular velocity fluctuation Ωzfc1 when the single micro-injection is executed and the angular velocity fluctuation Ωzfc0 when it is not executed is the reference micro-injection amount Qzfc1 obtained and stored in advance through experiments or the like. It is determined whether or not it matches the reference value ΔΩ0 of the difference in angular velocity fluctuation that occurs when fuel is injected. Steps S14 to S18 are repeated until the angular velocity fluctuation difference ΔΩzfc1 matches the reference value ΔΩ0. At this time, the value of the injection time ETa set in step S14 is changed each time.

  When the difference ΔΩzfc1 in the angular velocity fluctuation matches the reference value ΔΩ0, the process proceeds to step S19, and the injection time ETa at that time is set to ETa1, and in step S20, the obtained injection time ETa1 is set to the difference in angular velocity fluctuation as the reference value ΔΩ0. Is compared with a reference injection time ETa0 set in advance as an injection time to obtain the ratio of the injection time ETa1 to the reference injection time ETa0 (ETa1 / ETa0), thereby calculating the individual difference correction coefficient α.

  Returning to FIG. 7, when the individual difference correction coefficient α is calculated in step S <b> 1, in step S <b> 2, the calculation formula of the target injection amount Qtgt is multiplied by the individual difference correction coefficient α to perform correction. Next, in step S3, the property correction coefficient β is calculated. FIG. 9 shows a flow of calculation of the property correction coefficient β.

In the calculation flow of the individual difference correction coefficient α, first, in step S31, the accelerator operation amount Acc, the engine speed Ne, and the like are read, and then in step S32, the target fuel injection amount Qtgt is calculated.
Next, in step S33, it is determined whether or not the internal combustion engine is in a non-injection state based on the accelerator operation amount Acc, the target fuel injection amount Qtgt, and the like. If the internal combustion engine is not in the non-injection state, the property correction coefficient β cannot be calculated, and the process returns to step S31. On the other hand, when the internal combustion engine is in the non-injection state, the process proceeds to step S34, and after setting the injection interval ΔT of the two fixed time minute injections, the two fixed time minute injections are executed in step S35.

  Next, after detecting the fuel temperature Tf at this time in step S36, the angular velocity fluctuation Ωzfc2 of the internal combustion engine when two constant-time micro injections are executed in step S37 is detected, and in step S38, the two constants are detected. The angular velocity fluctuation Ωzfc0 of the internal combustion engine when the time minute injection is not executed is detected. Next, in step S39, after calculating a difference ΔΩzfc2 between the angular velocity fluctuation Ωzfc2 when the two fixed-time micro injections are executed and the angular velocity fluctuation Ωzfc0 when the two fixed-time micro injections are not executed, step S40 is performed. In step S1, it is determined whether or not the calculated number N of ΔΩzfc2 is equal to or larger than a preset specified value N0. Steps S34 to S40 are repeated until the calculated number N of ΔΩzfc2 becomes equal to or greater than the specified value N0. At this time, the value of the injection interval ΔT set in step S34 is changed each time.

  When the calculated number N of ΔΩzfc2 becomes equal to or greater than the specified value N0, in step S41, the difference ΔΩzfc2 between the angular velocity fluctuation Ωzfc2 when the two-time constant time minute injection is executed and the angular velocity fluctuation Ωzfc0 when the injection is not executed, and the injection interval A relationship with ΔT is required. Next, in step S42, based on the data indicating the relationship between the fuel injection amount Qact and the angular velocity variation difference ΔΩzfc, the fuel injection amount Qact and the injection are determined from the relationship between the angular velocity variation difference ΔΩzfc2 obtained in step S41 and the injection interval ΔT. A relationship with the interval ΔT is obtained.

  Next, in step S43, the fuel injection amount Qzfc3 is calculated from the fuel injection amount Qact corresponding to each injection interval ΔT based on the relationship between the injection interval ΔT of the two fixed minute injections and the fuel injection amount Qzfc3 stored in advance. After the subtraction, in step S44, the relationship between the injection interval ΔT of the two fixed time minute injections executed in step 35 and the rail pressure Prail, that is, the cycle Cpr of the rail pressure pulsation is calculated.

Next, in step S45, the pressure pulsation cycle Cpr, the fuel temperature Tfl, the fuel property (density) ρ, which are stored in advance when the fuel is injected at the injection time ETb1 of the first fixed time minute fuel injection stored in advance. The fuel property ρact of the used fuel is estimated on the basis of the pressure pulsation cycle Cpr and the fuel temperature Tfl at the time of executing the two constant-time microinjections. When the fuel property ρact of the fuel used is estimated, in step S46, the obtained use is obtained by referring to the data indicating the correlation between the fuel property (density) ρ0 of the reference fuel and the fuel temperature Tf stored in advance. The fuel property ρact of the fuel is converted into a correlation value Tf _ρ of the fuel temperature. In step S47, the property correction coefficient β is calculated according to the obtained correlation value Tf _ρ of the fuel temperature.

  Returning to FIG. 7, when the property correction coefficient β is calculated in step S3, in step S4, the arithmetic expression of the target injection amount Qtgt is multiplied by the property correction coefficient β, and correction is executed. Next, in step S5, fuel injection control is performed while calculating the target injection amount Qtgt according to the operating state of the internal combustion engine.

When calculating the target injection amount Qtgt of the internal combustion engine, it is common to correct the fuel injection amount based on the current fuel temperature Tf in consideration of the difference in fuel viscosity due to the difference in fuel temperature Tf. It is. In the control flow described above, correction is performed by a method of multiplying the property correction coefficient β by the calculated target injection amount Qtgt or an arithmetic expression of the target injection amount, but the current obtained in the process of calculating the property correction coefficient β By adding the fuel temperature correlation value Tf _ρ based on the fuel property ρact of the fuel used to the current fuel temperature Tf, the difference in the fuel property ρact can be reflected in the target injection amount.

FIG. 10 shows a flow of fuel injection control when the combustion property ρact of the used fuel is reflected in the target injection amount as a correlation value of the fuel temperature Tf. As a premise for executing this flow, the calculation flow of the property correction coefficient β shown in FIG. 9 described above ends in step S46 in which the correlation value Tf _ρ of the fuel temperature is obtained, and step S47 is omitted.

In the flow of FIG. 10, first, the accelerator operation amount Acc, the engine speed Ne, and the like are read in step S51, and further, the fuel temperature Tf is read in step S52. Next, in step S53, the fuel temperature correlation value Tf _ρ based on the fuel property ρact is added to the fuel temperature Tf read in step S52 to calculate the apparent temperature Tf ′.

  Thereafter, in step S54, a target injection amount Qtgt 'is calculated based on the read accelerator operation amount Acc, engine speed Ne, and apparent fuel temperature Tf'. In step S55, energization control to the fuel injection valve 13 is executed based on the target injection amount Qtgt 'calculated in step S54.

  As described above, according to the fuel injection control device and the fuel injection control method of the present embodiment, the position of the piston in the cylinder at the time of fuel injection differs depending on the difference between the two fuel injection intervals. The fuel property is estimated based on the angular velocity fluctuation excluding the influence of the angular velocity fluctuation. Therefore, the fuel property is accurately estimated, and the correction of the fuel injection amount is accurately executed based on the fuel property.

  In particular, the fuel injection control device and the fuel injection control method of the present embodiment eliminate not only variations in fuel injection amount due to fuel properties, but also differences in individual fuel injection valves and variations in fuel injection amount due to fuel temperature. The deviation between the quantity and the actual fuel injection quantity is reduced. Further, the fuel injection amount is corrected without increasing the number of executions of the target injection amount correction by adding the fuel property to the detected fuel temperature by converting the fuel property into a correlation value of the fuel temperature.

  Furthermore, in the fuel injection control device and the fuel injection control method according to the present embodiment, each correction coefficient is obtained by executing minute injection using the non-injection state of the internal combustion engine. The correction coefficient is obtained without making the driver feel uncomfortable due to the difference in the combustion state of the vehicle.

1: Fuel tank, 2: Electric low-pressure pump, 5: High-pressure pump, 6: Fuel intake valve, 7: Plunger, 8: Flow control valve, 9: Fuel discharge valve, 10: Common rail, 12: Pressure control valve, 13: Fuel injection valve, 14: pressure adjusting valve, 15: cam, 16: cam chamber, 18: low pressure fuel passage, 21: rail pressure sensor, 30a, 30b, 30c: return passage, 37, 39: high pressure fuel passage, 40: Internal combustion engine, 42: piston, 43: crankshaft, 45: crank angle sensor, 50: accumulator fuel injection device, 70: fuel injection control device, 71: target injection amount calculation unit, 72: no injection state detection unit, 73 : Angular velocity detection unit, 74: fuel temperature detection unit, 75: coefficient correction unit, 77: fuel injection amount correction unit, 79: fuel injection valve control unit, 80: individual difference correction coefficient calculation unit, 81: execution of one minute injection Control unit, 3: first correction coefficient calculation unit, 90: fuel property correction coefficient calculation unit, 91: twice constant-time small injection execution control unit, 93: pressure pulsation cycle calculating unit, 95: second correction coefficient calculator

Claims (10)

A target injection amount calculation unit that is used for controlling an accumulator fuel injection device that injects fuel accumulated in a common rail into a cylinder of an internal combustion engine by a fuel injection valve, and calculates a target fuel injection amount to each cylinder of the internal combustion engine And a fuel injection control unit that performs drive control of the fuel injection valve based on the target fuel injection amount,
A non-injection state detector for detecting a non-injection state of the internal combustion engine;
An angular velocity detector for detecting an angular velocity of the internal combustion engine;
When the non-injection state of the internal combustion engine is detected, two fixed-time injections performed at a predetermined injection interval are executed a plurality of times while changing the injection interval, and the two fixed-time injections are executed a plurality of times The fuel property of the fuel is estimated from the pressure pulsation period of the fuel obtained based on the angular velocity fluctuations of each of the internal combustion engines or the correlation value of the angular velocity fluctuations, and the target fuel injection amount or A property correction coefficient calculator for calculating a property correction coefficient for correcting the drive signal of the fuel injection valve;
A fuel injection amount correction unit that corrects the target fuel injection amount or the drive signal of the fuel injection valve by the property correction coefficient;
A coefficient correction unit that corrects the property correction coefficient based on an angular velocity variation of the internal combustion engine or a correlation value of the angular velocity variation, which is stored in advance only by the difference in the injection interval;
A fuel injection control device comprising:   The coefficient correction unit stores the injection interval and the angular velocity fluctuation or angular velocity fluctuation of the internal combustion engine when two constant injections, each of which is injected at a predetermined injection amount, are stored a plurality of times while changing the injection interval. The fuel injection control device according to claim 1, wherein the property correction coefficient is corrected based on a relationship with the correlation value. The property correction coefficient calculator is
When the non-injection state of the internal combustion engine is detected, the second injection timing in the cycle of the internal combustion engine is fixed, while the first injection timing is made different so that the two fixed-time injections are performed. A twice-injection execution control unit that executes a plurality of times while changing the injection interval;
Injection of the two constant-time injections by comparing the angular velocity fluctuation of each internal combustion engine when the two constant-time injections are executed a plurality of times with the angular speed fluctuation when the constant-time injection is not executed A pressure pulsation cycle calculating unit that calculates a relationship between the interval and the angular velocity fluctuation of the internal combustion engine, and calculates a cycle of the pressure pulsation of the fuel based on a relationship between the injection interval and the angular velocity fluctuation or a correlation value of the angular velocity fluctuation;
A correction coefficient calculation unit that estimates the fuel property according to the period of the pressure pulsation of the fuel and calculates the property correction coefficient based on the fuel property;
The fuel injection control device according to claim 1, comprising:   4. The pressure pulsation cycle calculating unit calculates the cycle of the pressure pulsation of the fuel by converting the angular velocity variation into a variation in fuel injection amount due to the two constant-time injections. Fuel injection control device.   The fuel injection control device according to any one of claims 1 to 4, wherein the fixed-time injection is micro injection.   The coefficient correction unit fixes the second injection timing stored in advance in the cycle of the internal combustion engine, while changing the injection interval by changing the first injection timing, and performs the two fixed injections. Based on the relationship between the injection interval of the two quantitative injections and the angular velocity fluctuation of the internal combustion engine when performed a plurality of times, the angular velocity fluctuation, the pressure pulsation period or the fuel injection amount in the pressure pulsation period calculation unit The fuel injection control device according to any one of claims 3 to 5, wherein the property correction coefficient is corrected by correcting at least one of the following. When the non-injection state of the internal combustion engine is detected, the fuel injection control device performs one microinjection a plurality of times while changing the injection time and performs the one microinjection. An injection time when the angular velocity fluctuation of the internal combustion engine becomes a preset reference fluctuation number is obtained, and the target fuel injection amount or the drive signal of the fuel injection valve is corrected based on the ratio between the injection time and the reference injection time An individual difference correction coefficient calculation unit for calculating an individual difference correction coefficient for performing
The fuel according to any one of claims 1 to 6, wherein the fuel injection amount correction unit further corrects the target fuel injection amount or the drive signal of the fuel injection valve by the individual difference correction coefficient. Injection control device.   The fuel injection control device according to any one of claims 1 to 7, wherein the property correction coefficient calculation unit obtains the property correction coefficient by converting the fuel property into a correlation value of the fuel temperature. . A target injection amount calculation unit for calculating a target fuel injection amount to each cylinder of the internal combustion engine, which is used in an accumulator fuel injection device that injects fuel accumulated in the common rail into a cylinder of the internal combustion engine by a fuel injection valve; A fuel injection control device comprising: a fuel injection valve control unit that performs drive control of the fuel injection valve based on the target fuel injection amount;
A non-injection state detector for detecting a non-injection state of the internal combustion engine;
An angular velocity detector for detecting an angular velocity of the internal combustion engine;
A one-time micro-injection execution control unit that executes one micro-injection a plurality of times while changing the injection time when a non-injection state of the internal combustion engine is detected;
Obtaining an injection time when the angular velocity fluctuation of the internal combustion engine when the one minute injection is executed becomes a preset reference fluctuation number, and based on the ratio of the injection time and the reference injection time A first correction coefficient calculator that calculates an individual difference correction coefficient for correcting the target fuel injection amount or the drive signal of the fuel injection valve;
When the non-injection state of the internal combustion engine is detected, the fixed injection time for the second time in the cycle of the internal combustion engine is fixed for the two fixed-time micro injections that are injected at a predetermined injection interval. A two-time fixed-time micro-injection execution control unit that executes a plurality of times while changing the injection interval by changing the injection timing of
By comparing the angular velocity fluctuation of each of the internal combustion engines when the two fixed-time micro injections are executed a plurality of times with the angular velocity fluctuation when the fixed-time micro injection is not executed, Find the relationship between the injection interval of time minute injection and the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation, and calculate the pressure pulsation cycle of the fuel based on the relationship between the injection interval and the angular velocity fluctuation or the correlation value A pressure pulsation cycle calculating unit to
The fuel property of the fuel is estimated according to the period of the pressure pulsation of the fuel, and a property correction coefficient for correcting the target fuel injection amount or the drive signal of the fuel injection valve is calculated based on the fuel property. A second correction coefficient calculation unit;
Two fixed minute injections, each of which is stored in advance at a predetermined injection amount, are fixed by fixing the second injection timing in the cycle of the internal combustion engine, while varying the first injection timing. Based on the relationship between the injection interval of the two quantitative micro-injections and the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular speed fluctuation when the interval is changed a plurality of times, the angular velocity fluctuation in the pressure pulsation cycle calculation unit or A coefficient correction unit that corrects at least one of the correlation value or the period of the pressure pulsation;
A fuel injection amount correction unit that corrects the target fuel injection amount or the drive signal of the fuel injection valve by the individual difference correction coefficient and the property correction coefficient;
A fuel injection control device comprising: In a fuel injection control method for correcting a fuel injection amount in an accumulator fuel injection device that injects fuel accumulated in a common rail into a cylinder of an internal combustion engine by a fuel injection valve,
When the non-injection state of the internal combustion engine is detected, two fixed-time injections performed at a predetermined injection interval are executed a plurality of times while changing the injection interval, and the two fixed-time injections are executed a plurality of times Determining the angular velocity fluctuation or angular velocity fluctuation correlation value of each internal combustion engine when
Based on the angular velocity fluctuation of the internal combustion engine or the correlation value of the angular velocity fluctuation, which is stored in advance, based on only the difference in the injection interval, the angular velocity fluctuation or the correlation value at the time of performing the two constant-time injections, Subtract the angular velocity fluctuation or its correlation value according to the injection interval,
Estimating the fuel property of the fuel according to the period of the pressure pulsation of the fuel obtained based on the value obtained by subtraction,
A fuel injection control method, wherein the target fuel injection amount or the drive signal of the fuel injection valve is corrected based on the fuel property.

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