JP6402745B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device.

  An electromagnetic fuel injection valve installed in an on-board engine has a valve body that opens in response to energization of the built-in electromagnetic solenoid, and the injection amount can be adjusted by changing the energization time of the electromagnetic solenoid. Has been. The valve body of the fuel injection valve bounces immediately after reaching the fully open position due to the reaction of the collision when it reaches the fully open position. Such a bounce motion of the valve body causes variations in the injection amount of the fuel injection valve. On the other hand, if injection is completed before the valve body reaches the fully open position, fuel injection can be performed without being affected by the bounce motion of the valve body. Therefore, conventionally, partial injection that achieves high-accuracy minute injection by performing fuel injection with the energization time set to a time shorter than the time required to reach the fully open position of the valve body, so-called partial lift injection. Lift injection technology has been proposed.

  On the other hand, the energization time of the fuel injection valve is determined based on the required injection amount calculated by correcting the base value set according to the engine speed and the engine load as necessary, and the fuel supplied to the fuel injection valve. It is set based on the pressure (fuel pressure). Although there are various corrections for the required injection amount, an increase correction according to a decrease in the engine speed during engine idling as described in Patent Document 1 is known.

JP 2011-106349 A

  By the way, a small amount of fuel injection realized by the partial lift injection as described above is used in a situation where precise injection control is required, and in such a situation, a slight change in the injection amount and injection timing, It greatly affects the combustion and exhaust properties of the engine. In particular, when the injection amount of the partial lift injection is increased, the penetration force of the fuel spray is increased, the distribution of the fuel concentration of the air-fuel mixture formed in the cylinder is changed, the spray reach distance is extended, and the piston top The fuel adheres to the surface and cylinder wall. Therefore, if the required injection amount is corrected to increase during the fuel injection by partial lift injection, the combustion and exhaust properties may be deteriorated.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide an engine control apparatus that can perform fuel injection by partial lift injection more suitably.

  An engine control device that solves the above problem is applied to an engine having a fuel injection valve, corrects a required injection amount calculated according to the operating state of the engine as needed, and fuel corresponding to the required injection amount. An injection control unit that controls the fuel injection valve to inject fuel. In the control device, the injection control unit is configured to provide fuel for the required injection amount through multistage injection including fuel injection by partial lift injection that ends injection before the valve body of the fuel injection valve reaches the fully open position. When the required injection amount is corrected to increase when the fuel is injected, the total injection amount of the multistage injection is changed to the amount of increase correction without changing the injection amount and injection timing of the fuel injection by the partial lift injection. The minute is increased.

  In such an engine control device, even when the increase in the required injection amount is corrected when multistage injection including fuel injection by partial lift injection is performed, changes in the injection amount and injection timing greatly affect the combustion and exhaust properties of the engine. The fuel injection by the partial lift injection is performed at the injection amount and the injection timing set from the beginning. Therefore, fuel injection by partial lift injection can be performed more suitably.

  The injection control unit in the engine control device increases the injection amount of the fuel injection other than the fuel injection by the partial lift injection in the multi-stage injection, so that the total amount of the multi-stage injection is corrected by the increase correction. It can be configured to increase by an amount. Further, the injection control unit adds the additional fuel injection by the partial lift injection separately from the fuel injection by the partial lift injection originally included in the multi-stage injection, thereby calculating the total amount of the injection of the multi-stage injection. It can also be configured to increase by the amount of increase correction.

  In the engine control device, the injection control unit performs the multi-stage injection during idle operation during catalyst warm-up of the engine, and in the multi-stage injection, the full lift injection that terminates the injection after the valve body reaches the fully open position. The fuel injection during the intake stroke and the fuel injection during the compression stroke by the partial lift injection can be performed. In such a case, fuel injection during the compression stroke by partial lift injection is performed to locally increase the fuel concentration around the spark plug. When the fuel injection amount and the fuel injection timing are changed, the injected fuel cannot be collected around the spark plug, or the fuel adhesion on the cylinder wall surface or the piston top surface is increased, resulting in deterioration of combustion. In this respect, in the engine control device, even when the required injection amount is corrected to increase, the fuel injection amount and the injection timing during the compression stroke by such partial lift injection are not changed, so that deterioration of combustion can be avoided. In addition, as an increase correction of the required injection amount performed during the execution of the multi-stage injection at the time of idling operation during the catalyst warm-up of the engine as described above, for example, there is one performed when the deterioration of the combustion state is confirmed. .

1 is a schematic diagram schematically showing the configuration of an engine fuel system to which a first embodiment of an engine control device is applied. Sectional drawing of the cylinder injection valve provided in the fuel system of the engine. The graph which shows the relationship between the injection amount of the same cylinder injection valve, its variation, and energization time. The flowchart of the process routine which concerns on the rotation stabilization control at the time of the rapid catalyst warm-up performed in the engine control apparatus of 1st Embodiment. The figure which shows allocation of the injection quantity of each injection in each at the time of the base in the control apparatus of the embodiment, and enrichment increase. The figure which shows the formation aspect of the fuel spray in a cylinder when partial lift injection is performed with the injection quantity set from the beginning. The figure which shows the formation aspect of the fuel spray in a cylinder when partial lift injection is performed with the injection quantity which carried out increase correction | amendment. The figure which shows allocation of the injection quantity of each injection in each at the time of the base in the engine control apparatus of 2nd Embodiment, and the enrichment increase. The figure which shows allocation of the injection quantity of each injection in each at the time of the base in the engine control apparatus of 3rd Embodiment, and the enrichment increase.

(First embodiment)
Hereinafter, a first embodiment of an engine control device will be described in detail with reference to FIGS.
<Configuration>
As shown in FIG. 1, an air cleaner 12, an air flow meter 13, a throttle valve 14, and an intake manifold 11 </ b> A are provided in order from the upstream side in an intake passage 11 of an engine 10 to which the control device of the present embodiment is applied. . The air cleaner 12 filters dust in the intake air flowing into the intake passage 11, the air flow meter 13 detects the flow rate of intake air (intake air amount GA), and the throttle valve 14 sucks in through the change of the valve opening. Adjust the air volume. The intake passage 11 is branched in the intake manifold 11A and then connected to each cylinder 16 through an intake port 15 for each cylinder.

  Each cylinder 16 of the engine 10 is provided with a piston 16A that can reciprocate. Each cylinder 16 is provided with a spark plug S that ignites the air-fuel mixture by spark discharge (see FIGS. 6 and 7).

  On the other hand, in the exhaust passage 17 of the engine 10, an exhaust manifold 17A, an air-fuel ratio sensor 18, and a catalyst device 19 are provided in order from the upstream side. The exhaust discharged from each cylinder 16 to the exhaust passage 17 is merged in the exhaust manifold 17A, flows into the catalyst device 19, and is purified in the catalyst device 19. The air-fuel ratio sensor 18 outputs a signal corresponding to the air-fuel ratio at the time of combustion of the exhaust gas flowing into the catalyst device 19.

  Such a fuel supply system of the engine 10 includes a feed pump 21 that pumps and discharges fuel in the fuel tank 20. The feed pump 21 is connected to a low pressure fuel pipe 23 and a high pressure fuel pump 24 via a low pressure fuel passage 22. The low-pressure fuel pipe 23 is a fuel container that stores fuel sent from the feed pump 21, and is connected to the port injection valve 25 of each cylinder 16 of the engine 10. The port injection valve 25 is configured as an electromagnetic fuel injection valve that injects fuel stored in the low-pressure fuel pipe 23 into the intake port 15 of the engine 10 in response to energization. On the other hand, the high-pressure fuel pump 24 further pressurizes the fuel sent from the feed pump 21 and discharges it to the high-pressure fuel pipe 26. The low-pressure fuel passage 22 opens when the fuel pressure (feed pressure) in the low-pressure fuel passage 22 exceeds a specified relief pressure by a filter 27 that filters the fuel discharged from the feed pump 21 and the low-pressure fuel passage 22 opens. A pressure regulator 28 for relieving the fuel in the passage 22 into the fuel tank 20 is provided.

  In the high-pressure fuel pump 24, two volume portions of a fuel gallery 29 and a pressurizing chamber 30 are provided. Fuel sent from the feed pump 21 through the low-pressure fuel passage 22 is introduced into the fuel gallery 29. In the fuel gallery 29, a pulsation damper for attenuating the pulsation of the fuel pressure is provided. Further, the high-pressure fuel pump 24 is provided with a plunger 34 which is reciprocated by a pump driving cam 33 provided on the cam shaft 32 of the engine 10 to change the volume of the pressurizing chamber 30.

  The fuel gallery 29 and the pressurizing chamber 30 are connected via an electromagnetic spill valve 35. The electromagnetic spill valve 35 is a normally open valve that closes in response to energization, and communicates the fuel gallery 29 and the pressurizing chamber 30 when the valve is opened, and blocks the communication when the valve is closed. Further, the pressurizing chamber 30 communicates with the high-pressure fuel pipe 26 through the check valve 36. The check valve 36 opens when the pressure in the pressurization chamber 30 becomes higher than that in the high-pressure fuel pipe 26, and allows fuel discharge from the pressurization chamber 30 to the high-pressure fuel pipe 26. The valve is closed when the pressure inside the pressurized chamber 30 becomes higher than that in the pressurized chamber 30 to restrict the back flow of fuel from the high pressure fuel pipe 26 to the pressurized chamber 30.

  The high-pressure fuel pipe 26 is a fuel container that stores high-pressure fuel sent from the high-pressure fuel pump 24, and an in-cylinder injection valve 37 installed in each cylinder 16 of the engine 10 is connected to the high-pressure fuel pipe 26. The in-cylinder injection valve 37 is configured as an electromagnetic fuel injection valve that injects fuel stored in the high-pressure fuel pipe 26 into the cylinder 16 in response to energization. A fuel pressure sensor 38 for detecting the internal fuel pressure (high pressure side fuel pressure) is attached to the high pressure fuel pipe 26. The high-pressure fuel pipe 26 is also provided with a relief valve 39A that opens when the internal pressure is excessively increased and relieves the internal fuel into the fuel tank 20 through the relief passage 39. .

  Further, the engine fuel supply system includes an electronic control unit 40. The electronic control unit 40 temporarily stores a central processing unit that performs various arithmetic processing, a read-only memory in which programs and data for the arithmetic processing are stored in advance, arithmetic results of the central processing unit, detection results of various sensors, and the like. A readable / writable memory is provided. The electronic control unit 40 includes a nonvolatile memory for storing and holding data even when the power is turned off.

  The electronic control unit 40 includes a crank angle sensor 41 that detects the rotational phase (crank angle) of the crankshaft of the engine 10 in addition to the air flow meter 13, the air-fuel ratio sensor 18, and the fuel pressure sensor 38, and a driver's accelerator pedal. A detection signal of a sensor such as an accelerator pedal sensor 42 for detecting the depression amount of the pedal is input. The electronic control unit 40 performs energization control of the electromagnetic spill valve 35, the port injection valve 25, and the in-cylinder injection valve 37 of the high-pressure fuel pump 24 based on the detection results of these sensors. The electronic control unit 40 calculates the engine speed NE from the detection result of the crank angle sensor 41 and calculates the engine load factor KL from the detection results of the air flow meter 13 and the accelerator pedal sensor 42. The engine load factor KL represents a ratio of the current cylinder inflow air amount when the maximum value of the cylinder inflow air amount at the current engine speed NE in natural intake is set to “100%”. Used as an index value.

<Fuel pressure control>
The electronic control unit 40 performs variable control of the high-pressure side fuel pressure Pm, which is the fuel pressure in the high-pressure fuel pipe 26, through energization control of the electromagnetic spill valve 35 of the high-pressure fuel pump 24. First, the pressurizing operation of the high-pressure fuel pump 24 will be described. In the following description, the movement of the plunger 34 in the direction of reducing the volume of the pressurizing chamber 30 in the reciprocating movement of the plunger 34 by the pump driving cam 33 is referred to as raising the plunger 34. Further, the movement of the plunger 34 in the direction of enlarging the volume of the pressurizing chamber 30 is referred to as lowering of the plunger 34.

  The fuel discharged from the feed pump 21 is introduced into the fuel gallery 29 of the high pressure fuel pump 24 through the low pressure fuel passage 22. Here, when the plunger 34 is lowered while the electromagnetic spill valve 35 is open, the fuel is sucked into the pressurizing chamber 30 from the fuel gallery 29 in accordance with the expansion of the volume of the pressurizing chamber 30. Thereafter, when the plunger 34 changes from descending to ascending, the volume of the pressurizing chamber 30 gradually decreases. If the electromagnetic spill valve 35 remains open at this time, the fuel is returned from the pressurizing chamber 30 to the fuel gallery 29 in accordance with the reduction of the volume. When energization to the electromagnetic spill valve 35 is started while the plunger 34 is raised, the electromagnetic spill valve 35 is closed and the pressurizing chamber 30 is sealed. Therefore, the fuel pressure in the pressurizing chamber 30 increases as the volume decreases. When the fuel pressure in the pressurizing chamber 30 becomes higher than the fuel pressure in the high-pressure fuel pipe 26, the check valve 36 is opened, and the fuel in the pressurizing chamber 30 that has become high pressure is pumped to the high-pressure fuel pipe 26. Thereafter, if energization to the electromagnetic spill valve 35 is stopped when the plunger 34 changes from rising to lowering, the fuel is again sucked into the pressurizing chamber 30 from the fuel gallery 29 in accordance with the lowering of the plunger 34. The high-pressure fuel pump 24 repeatedly pressurizes and discharges fuel to the high-pressure fuel pipe 26 by repeating the suction of the fuel when the plunger 34 is lowered and the pressurized discharge of the fuel when the plunger 34 is raised.

  The amount of fuel discharged by the high-pressure fuel pump 24 each time the plunger 34 is moved up and down once (hereinafter referred to as the fuel discharge amount of the high-pressure fuel pump 24) is an electromagnetic spill valve during the ascending period of the plunger 34. It increases if the start time of energization to 35 is advanced, and decreases if it is delayed. The electronic control unit 40 performs fuel pressure variable control that makes the high-pressure side fuel pressure Pm in the high-pressure fuel pipe 26 variable by adjusting the energization start timing of the electromagnetic spill valve 35.

  In the fuel pressure variable control, the electronic control unit 40 first calculates a target fuel pressure Pt that is a target value of the high-pressure side fuel pressure Pm based on the engine load factor KL and the like. The target fuel pressure Pt is basically set to a low pressure when the engine load factor KL is low and to a high pressure when the engine load factor KL is high.

  Then, the electronic control unit 40 detects the electromagnetic spill during the ascending period of the plunger 34 so that the high-pressure side fuel pressure Pm approaches the target fuel pressure Pt according to the deviation between the high-pressure side fuel pressure Pm detected by the fuel pressure sensor 38 and the target fuel pressure Pt. The energization start time of the valve 35 is adjusted. Specifically, when the high-pressure side fuel pressure Pm is lower than the target fuel pressure Pt, the energization start timing of the electromagnetic spill valve 35 is advanced to increase the fuel discharge amount of the high-pressure fuel pump 24. When the high-pressure side fuel pressure Pm is higher than the target fuel pressure Pt, the energization start timing of the electromagnetic spill valve 35 is delayed and the fuel discharge amount of the high-pressure fuel pump 24 is decreased. Thus, the electronic control unit 40 feedback-adjusts the fuel discharge amount of the high-pressure fuel pump 24 in order to maintain the high-pressure side fuel pressure Pm at the target fuel pressure Pt.

<Fuel injection control>
The electronic control unit 40 also controls fuel injection by the port injection valve 25 and the in-cylinder injection valve 37. The fuel injection control is performed in the following manner.

  In the fuel injection control, the electronic control unit 40 first calculates the required injection amount Qt based on the engine operating status (engine speed NE, engine load factor KL, etc.). The required injection amount Qt is a required value of the total amount of fuel injected per combustion cycle in each cylinder. Further, the electronic control unit 40 determines the injection ratio of the port injection valve 25 and the in-cylinder injection valve 37 based on the operating state of the engine. The electronic control unit 40 then determines the required injection amount Qt according to the injection ratio, the port injection amount Qi that is the amount of fuel injected by the port injection valve 25, and the amount of fuel injected by the in-cylinder injection valve 37. To the in-cylinder injection amount Qd. Further, the electronic control unit 40 sets the energization time of the port injection valve 25 required for fuel injection for the port injection amount Qi and the energization time of the in-cylinder injection valve 37 required for fuel injection for the in-cylinder injection amount Qd, respectively. Calculate. The electronic control unit 40 is configured to energize the port injection valve 25 and the in-cylinder injection valve 37 for each calculated energization time.

  Note that, as described above, the high-pressure side fuel pressure Pm supplied with fuel to the in-cylinder injection valve 37 is variably controlled. If the high-pressure side fuel pressure Pm changes, the amount of fuel injected by the in-cylinder injection valve 37 per unit time changes depending on energization. Therefore, the electronic control unit 40 refers to the high-pressure side fuel pressure Pm detected by the fuel pressure sensor 38 and calculates the energization time necessary for fuel injection for the in-cylinder injection amount Qd.

<Partial lift injection>
Incidentally, the in-cylinder injection valve 37 that injects higher pressure fuel injects more fuel in a short period of time compared to the port injection valve 25 that injects lower pressure fuel. In such an in-cylinder injection valve 37, the following structural problem greatly affects the injection amount accuracy in a small amount of fuel injection.

FIG. 2 shows a cross-sectional structure of the cylinder injection valve 37. In the following description, the lower side in the figure is referred to as the front end side of the in-cylinder injection valve 37.
As shown in the figure, an electromagnetic solenoid 51 is built in the housing 50 of the in-cylinder injection valve 37. The electromagnetic solenoid 51 includes a fixed core 52 fixed to the housing 50, an electromagnetic coil 53 provided around the fixed core 52, and a movable core 54 provided adjacent to the fixed core 52 on the distal end side. . The movable core 54 is installed in the housing 50 so as to be displaceable in the vertical direction in the figure, and the valve body 55 is integrally connected so as to be displaceable. Further, a spring 56 that urges the movable core 54 toward the distal end side is also provided in the housing 50.

  On the other hand, a nozzle body 57 is attached to the front end portion of the housing 50 so as to surround the periphery of the front end portion of the valve body 55. A slit-like injection hole 58 that communicates the inside and the outside of the nozzle body 57 is formed at the tip of the nozzle body 57. A fuel chamber 59 into which the fuel sent from the high pressure fuel pipe 26 is introduced is formed inside the housing 50.

  In such an in-cylinder injection valve 37, the valve body 55 is urged toward the distal end side together with the movable core 54 by a spring 56. When the electromagnetic solenoid 51 is not energized, the urging force of the spring 56 causes the valve body 55 to be displaced to a position where it is seated on the nozzle body 57 (hereinafter referred to as a fully closed position). The hole 58 is closed.

  When energization of the electromagnetic solenoid 51 is started, an electromagnetic attractive force is generated between the fixed core 52 and the movable core 54, and the valve body 55 is displaced together with the movable core 54 toward the side closer to the fixed core 52. As a result, when the tip of the valve body 55 leaves the nozzle body 57, the injection hole 58 is opened, and the fuel in the fuel chamber 59 is injected to the outside. The valve body 55 is displaceable to a position where the movable core 54 abuts the fixed core 52 (hereinafter referred to as a fully opened position) with respect to the side where the tip is separated from the nozzle body 57.

  Thereafter, when energization to the electromagnetic solenoid 51 is stopped, the valve body 55 is displaced toward the fully closed position. When the valve body 55 reaches the fully closed position, the injection hole 58 is closed and fuel injection is stopped. In the following description, the bed leaving amount at the tip of the valve body 55 with respect to the nozzle body 57 is described as the nozzle lift amount of the in-cylinder injection valve 37.

  FIG. 3 shows the relationship between the energization time for the electromagnetic solenoid 51, the injection amount of the in-cylinder injection valve 37, and its variation. In the figure, “T0” indicates the energization time (lift start energization time) required for starting the bed 55 (lift) of the valve body 55 from the nozzle body 57, and “Tpmax” indicates that the valve body 55 is fully opened. The energization time (P / L maximum energization time) required for reaching is shown respectively.

  In the section from “T0 to Tpmax”, the nozzle lift amount changes during energization, so the rate of change of the injection amount of the in-cylinder injection valve 37 with respect to the energization time becomes relatively large. On the other hand, in the section after “Tpmax”, the nozzle lift amount is maintained at the fully opened amount, so the rate of change of the injection amount of the in-cylinder injection valve 37 with respect to the energization time is compared with the section from “T0 to Tpmax”. And get smaller. In the following description, a section from “T0 to Tpmax” where the valve body 55 does not fully open is described as a partial lift (P / L) section. Further, a section after “Tpmax” in which the valve element 55 is fully opened is referred to as a full lift (F / L) section.

  There is some variation in the time from the start of energization to the start of lift of the valve body 55 (lift start energization time TO), and this variation causes the variation in the injection amount in the P / L section. However, since the influence of the variation in the lift start energization time TO on the variation in the injection amount becomes relatively small as the injection amount increases, the variation in the injection amount in the P / L section decreases as the energization time increases. To do.

  On the other hand, when the valve body 55 in which the movable core 54 comes into contact with the fixed core 52 reaches the fully open position, the valve body 55 bounces due to the reaction of the collision between the movable core 54 and the fixed core 52. The minute vibration of the nozzle lift amount due to the bounce motion increases the variation in the injection amount. The influence that the bounce motion of the valve body 55 at the time of full opening has on the variation in the injection amount also becomes relatively small as the injection amount increases. Therefore, the variation in the injection amount of the in-cylinder injection valve 37 once increases immediately after entering the F / L section, and then decreases as the energization time increases. Therefore, if the fuel injection is performed with the energization time set longer than the specified time (F / L minimum energization time Tfmin) longer than the P / L maximum energization time Tpmax, the variation in the injection amount can be suppressed to an allowable value or less. It becomes possible.

  On the other hand, as described above, also in the P / L section, the variation in the injection amount is relatively small during the energization time immediately before entering the F / L section. Therefore, even if the energization time is set to a range not less than the specified time (P / L minimum energization time Tpmin) and less than the P / L maximum energization time Tpmax, the variation in the injection amount can be suppressed to an allowable value or less. In the present embodiment, by setting the energization time in such a range and performing fuel injection in which the valve body 55 does not reach full open, so-called partial lift injection, a very small amount of fuel injection by the in-cylinder injection valve 37 is high injection. It is done with quantity accuracy. Incidentally, in contrast to such partial lift injection, fuel injection in which the valve body 55 is fully opened is referred to as full lift injection.

  Incidentally, the port injection valve 25 has the same structural problem. However, even when the port injection amount Qi is the lower limit value of the control range, the energization time of the port injection valve 25 is longer than the F / L minimum energization time Tfmin of the port injection valve 25. All the fuel injections are performed by full lift injection in which the valve body is fully opened.

<Rotational stabilization control during rapid catalyst warm-up>
In the present embodiment, in order to warm up the catalyst device 19 more rapidly, the fuel injection control is performed in the following manner when the engine 10 is cold started. That is, at the time of cold start of the engine 10, the request is made through multi-stage injection of the fuel injection during the intake stroke by the full lift injection of the cylinder injection valve 37 and the fuel injection during the compression stroke by the partial lift injection of the cylinder injection valve 37. The fuel for the injection amount Qt is injected. Furthermore, in the present embodiment, rotation stabilization control for stabilizing the engine speed NE is performed during rapid catalyst warm-up when the engine 10 is cold started.

  FIG. 4 shows a processing routine of the electronic control unit 40 related to the rotation stabilization control during rapid catalyst warm-up. The processing of this routine is repeatedly executed at regular control intervals by the electronic control unit 40 during the warm-up period of the catalyst device 19. In the present embodiment, the electronic control unit 40 estimates the catalyst bed temperature of the catalyst device 19 from the coolant temperature of the engine 10 and the integrated value of the fuel injection amount after the engine 10 is started. The electronic control unit 40 sets a period from when the engine 10 is started until the estimated catalyst bed temperature reaches a specified warm-up determination value as the warm-up period of the catalyst device 19.

  When the processing of this routine is started, first, in step S100, the required injection amount Qt is calculated based on the engine speed NE and the engine load factor KL. The value of the required injection amount Qt at this time is calculated so that the air-fuel ratio of the air-fuel mixture burned in the cylinder 16 becomes the specified target air-fuel ratio.

  Subsequently, in step S101, based on the engine speed NE and the high-pressure side fuel pressure Pm, a P / L injection amount Qp that is an injection amount of fuel injection by partial lift injection during the compression stroke in the multistage injection is calculated. In the subsequent step S102, the F / L injection amount Qf, which is the fuel injection amount of the full lift injection during the intake stroke in the multistage injection, is obtained by subtracting the P / L injection amount Qp from the required injection amount Qt. Calculated.

Continued There, at step S103, whether or not the amount of decrease in the engine rotational speed NE with respect to a preset target idle speed NT ΔNE (= NT-NE) is defined first determination value α or more is determined. As the value of the first determination value α, a difference (= NT−NEmin) between the target idle speed NT and the allowable lower limit NEmin of the engine speed NE during idle operation is set.

  If the amount of decrease ΔNE is less than the first determination value α (S103: NO), the process proceeds to step S104. In step S104, air amount feedback is performed. The air amount feedback is feedback adjustment of the opening degree of the throttle valve 14 based on the decrease amount ΔNE of the engine speed NE so as to increase / decrease the intake air amount GA of the engine 10 so that the decrease amount ΔNE approaches “0”. It is done by doing. That is, when the reduction amount ΔNE is a negative value, that is, when the engine speed NE exceeds the target idle speed NT, the opening degree of the throttle valve 14 is gradually reduced in order to reduce the intake air amount GA. When the decrease amount ΔNE is a positive value, that is, when the engine speed NE is below the target idle speed NT, the opening of the throttle valve 14 is gradually increased to increase the intake air amount GA. In the air amount feedback, a prescribed maximum idle air amount GAmax is set as the upper limit value of the intake air amount GA. That is, the increase in the intake air amount GA in the air amount feedback is limited until the intake air amount GA reaches the maximum idle air amount GAmax.

  Subsequently, in step S105, it is determined whether or not the fluctuation amount ω of the engine speed NE exceeds a prescribed allowable value γ. In the present embodiment, the fluctuation amount ω of the engine speed NE is obtained as follows. That is, the electronic control unit 40 measures the time required for rotation of the crankshaft for a specified crank angle at regular intervals. Then, the electronic control unit 40 obtains the difference between the currently measured time and the gradually changing value of the time measured so far as the fluctuation amount ω of the engine speed NE.

  Here, if the fluctuation amount ω is equal to or smaller than the allowable value γ (S105: NO), the processing of this routine is terminated as it is. On the other hand, if the fluctuation amount ω exceeds the allowable value γ (S105: YES), the process proceeds to step S108. In step S108, the required injection amount Qt for increasing the air-fuel ratio is increased. After the correction is performed, the process of this routine is terminated. Specific contents of the processing relating to the increase correction of the required injection amount Qt at this time will be described in detail later.

  On the other hand, if the decrease amount ΔNE is greater than or equal to the first determination value α (S103: YES), the process proceeds to step S106, and ignition timing feedback is performed in step S106. In the ignition timing feedback, the ignition timing by the spark plug S is feedback-adjusted so that the decrease amount ΔNE of the engine speed NE is less than the first determination value α. Specifically, when the reduction amount ΔNE of the engine speed NE is greater than or equal to the first determination value α, the ignition timing is gradually advanced.

  Next, in step S107, it is determined whether or not the decrease amount ΔNE of the engine speed NE is equal to or greater than a prescribed second determination value β. The second determination value β is set to a value larger than the first determination value α. Here, if the amount of decrease ΔNE is less than the second determination value β (S107: NO), the process proceeds to step S105 described above. In this case, if it is determined in step S105 that the fluctuation amount ω of the engine speed NE is equal to or less than the allowable value γ, the current process is terminated, and it is determined that the fluctuation amount ω exceeds the allowable value γ. Then, in step S108, the required injection amount Qt is enriched and increased.

  On the other hand, if the decrease amount ΔNE is greater than or equal to the second determination value β (S107: YES), the process proceeds directly to step S108. That is, in this case, the required injection amount Qt is enriched and increased regardless of the amount of fluctuation ω of the engine speed NE.

  The increase correction of the required injection amount Qt for enriching the air-fuel ratio in step S108 in this routine is performed in the following manner. In the following description, the time when the increase correction of the required injection amount Qt is not performed is referred to as the base time, and the time when it is performed is referred to as the rich increase time.

  That is, at the time of enrichment increase, the value of the F / L injection amount Qf is updated to a value obtained by multiplying the value calculated in step S102 by the specified increase coefficient Kr. On the other hand, the P / L injection amount Qp is held at the value calculated in step S101. Therefore, even when the enrichment is increased, the fuel injection during the intake stroke by full lift injection and the fuel injection during the compression stroke by partial lift injection (the timing at which injection starts) are maintained at the same time as the base time. .

  As shown in FIG. 5, the increase correction of the required injection amount Qt at the time of the enrichment increase is the fuel by the full lift injection (F / L injection) during the intake stroke among the multi-stage injections performed for rapid catalyst warm-up. This is performed by increasing only the injection amount (F / L injection amount Qf). Therefore, when the enrichment is increased, the fuel injection amount (P / L injection amount Qp) by partial lift injection (P / L injection) and the total injection amount of the multistage injection are not changed from the base time. However, it is increased by the amount of the increase correction due to the enrichment increase.

<Action>
Next, the operation of the engine control apparatus of the present embodiment described above will be described.
When the engine 10 is cold started, the cylinder wall surface temperature is low and the amount of fuel adhering to the cylinder wall surface increases, so the air-fuel ratio becomes lean, and ignition of the air-fuel mixture by the spark plug S may be difficult. As a result, the combustion state deteriorates, the exhaust temperature decreases, and there is a possibility that warming up of the catalyst device 19 is delayed. Therefore, in the engine control apparatus of the present embodiment, when the engine 10 is cold-started, the combustion state is achieved by performing multi-stage injection of fuel injection by full lift injection during the intake stroke and fuel injection by partial lift injection during the compression stroke. The warming up of the catalyst device 19 is promoted by suppressing the deterioration of the catalyst.

  As shown in FIG. 6, the fuel injection by the partial lift injection during the compression stroke at this time places the spray A of the injected fuel on the in-cylinder airflow F formed in the cylinder 16 during the compression stroke, The injection amount and the injection timing are set so as to be collected in the vicinity of the spark plug S. If such partial lift injection is performed, fuel adhesion increases, and even if the air-fuel ratio of the air-fuel mixture in the entire cylinder 16 becomes lean, a sufficiently rich air-fuel mixture exists in the vicinity of the spark plug S. . Therefore, the air-fuel mixture can be ignited satisfactorily and the deterioration of the combustion state is suppressed, so that the exhaust temperature is prevented from lowering and the warming-up of the catalyst device 19 is promoted.

  Further, in the engine control apparatus of the present embodiment, during such rapid catalyst warm-up, rotation stabilization control is performed to maintain the engine speed NE at the target idle speed NT. In the rotation stabilization control, the air amount feedback, the ignition timing feedback, and the required injection amount Qt are enriched according to the amount of decrease ΔNE of the engine speed NE with respect to the target idle speed NT and the fluctuation amount ω of the engine speed NE. While properly using the correction, the engine speed NE is adjusted to maintain the target idle speed NT.

  Specifically, when the decrease amount ΔNE is less than the first determination value α, the variation amount ω is equal to or less than the allowable value γ, and the engine speed NE is relatively stable, the engine is obtained only by air amount feedback. Adjust the rotational speed NE. If the engine speed NE at this time is lower than the target idle speed NT, the intake air amount GA is increased by the air amount feedback, and the required injection amount Qt is also increased at the same time. Therefore, the torque generated by the engine 10 increases and the engine speed NE increases. On the other hand, if the engine speed NE exceeds the target idle speed NT, the intake air amount GA is reduced by the air amount feedback, and the required injection amount Qt is also reduced at the same time. As a result, the torque generated by the engine 10 decreases and the engine speed NE decreases.

  On the other hand, when the engine speed NE is greatly reduced, the intake air amount GA reaches the maximum idle air amount GAmax, and it may not be possible to increase the engine speed NE beyond that with the air amount feedback. In such a case, because of the intake air conveyance delay, there is a possibility that the engine stall cannot be avoided only by the air amount feedback that requires a certain time for the feedback result to be reflected in the engine speed NE. Accordingly, when the decrease amount ΔNE is equal to or greater than the first determination value α, ignition timing feedback is performed to adjust the engine speed NE.

  If the amount of fuel adhering to the cylinder wall surface is too large, ignition may not be performed well even if multistage injection including partial lift injection during the compression stroke described above is performed, and misfire may occur. Even if misfire does not occur, there is a possibility that the propagation of the flame after ignition becomes slow and the combustion becomes slow. When such deterioration of the combustion state occurs intermittently, the fluctuation amount ω of the engine speed NE increases. Therefore, in the present embodiment, when the amount of decrease ΔNE of the engine speed NE is less than the second determination value β, when the variation amount ω exceeds the allowable value γ, the required injection amount Qt is enriched and increased. When the enrichment increase is performed, the required injection amount Qt is increased beyond what is necessary to make the air-fuel ratio the target air-fuel ratio, and the air-fuel ratio becomes rich. Therefore, the deterioration of the combustion state due to the lean air-fuel ratio can be suppressed.

  Note that when the engine speed NE is greatly decreased until the decrease amount ΔNE becomes equal to or greater than the second determination value β, the deterioration of the combustion state is normal, and the value of the fluctuation amount ω even if the combustion state is deteriorated. May not grow. Therefore, when the decrease amount ΔNE is equal to or greater than the second determination value β, the increase correction of the required injection amount Qt for enriching the air-fuel ratio is performed regardless of the magnitude of the variation amount ω.

  In the present embodiment, when the multi-stage injection of the fuel injection by the full lift injection during the intake stroke and the fuel injection by the partial lift injection during the compression stroke is performed, the increase correction of the required injection amount Qt is performed. In the increase correction at this time, if both the F / L injection amount Qf and the P / L injection amount Qp are increased, the following problem occurs.

  As described above, the injection amount of the in-cylinder injection valve 37 is controlled by the energization time. The greater the injection amount, the longer the energization time of the in-cylinder injection valve 37. On the other hand, in the partial lift section, the lift amount of the valve body 55 increases according to the energization time, and the fuel injection pressure increases at the same time. Therefore, if the P / L injection amount Qp is increased, the penetration force of the injected fuel becomes high.

  As shown in FIG. 7, when the penetration force of the fuel injected by the partial lift injection during the compression stroke becomes high, the reach distance of the spray A is extended, and the spray A escapes the in-cylinder airflow F. Therefore, the fuel injected by the partial lift injection during the compression stroke cannot be collected near the spark plug S, and the combustion state cannot be improved. In this regard, in this embodiment, even when the required injection amount Qt is enriched and increased, the fuel injection amount (P / L injection amount Qp) and injection timing by partial lift injection during the compression stroke are not changed from the base time. The combustion improvement effect by the injection is maintained.

According to the engine control apparatus of the present embodiment described above, the following effects can be obtained.
(1) Full correction without changing the fuel injection amount (P / L injection amount Qp) and the injection timing by partial lift injection during the compression stroke when increasing the required injection amount Qt for air-fuel ratio enrichment correction The total amount of injection by injection and partial lift injection is increased by the increase correction. Therefore, the combustion improvement effect by the partial lift injection during the compression stroke can be maintained even when the required injection amount Qt is increased.

  (2) The air-fuel ratio can be enriched while maintaining the combustion improvement effect by partial lift injection. Therefore, deterioration of the combustion state can be more effectively suppressed by both partial lift injection and enrichment of the air-fuel ratio.

  (3) When the engine speed NE decreases until the decrease amount ΔNE with respect to the target idle speed NT becomes equal to or greater than the first determination value α, ignition timing feedback is performed. Therefore, it is possible to recover the engine speed NE to the target idle speed NT more quickly and reliably. Note that the change in the ignition timing may cause deterioration in exhaust properties. Therefore, when the amount of decrease in the engine speed NE is small, it is possible to suppress the deterioration of the exhaust properties by not performing the ignition timing feedback.

  (4) When the combustion state deteriorates and the fluctuation amount ω of the engine speed NE exceeds the allowable value γ, the required injection amount Qt is increased and corrected to enrich the air-fuel ratio. Therefore, it is possible to stabilize the engine speed NE while suppressing deterioration of the combustion state.

  (5) When the engine speed NE decreases until the decrease amount ΔNE with respect to the target idle speed NT becomes equal to or greater than the second determination value β, the required injection amount Qt is increased and corrected regardless of the amount of variation ω. The fuel ratio is enriched. Therefore, even when the deterioration of the combustion state becomes normal, the increase correction of the required injection amount Qt for enriching the air-fuel ratio is reliably performed.

(Second Embodiment)
Next, a second embodiment of the engine control device will be described in detail with reference to FIG. In addition, in this embodiment, about the structure which is common in the said embodiment, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 8, in the present embodiment, the number of partial lift injections (P / L injections) is increased with respect to the base time when the enrichment is increased. In other words, in this embodiment, by adding further fuel injection by partial lift injection separately from fuel injection by partial lift injection included in multi-stage injection from the base time, the total amount of injection of multi-stage injection is increased and corrected. I try to increase the amount. In the following description, fuel injection of partial lift injection included in multistage injection from the base time is described as fuel injection by partial lift injection for the base.

  In the present embodiment, the fuel injection by the additional partial lift injection is performed during the compression stroke and at the timing after the fuel injection by the partial lift injection for the base. Further, the injection amount of each injection at this time is set as follows. First, the value of the required injection amount Qt is updated to a value obtained by multiplying the value calculated based on the engine speed NE and the engine load factor KL by the increase coefficient Kr. Next, the injection amount of the partial lift injection for both the base portion and the additional portion is calculated. Here, the injection amount of the additional partial lift injection is the same as the injection amount of the partial lift injection for the base. A value obtained by subtracting the sum of the injection amounts of both partial lift injections from the updated required injection amount Qt is set as the value of the F / L injection amount Qf.

  Also in the engine control device of this embodiment, when the increase correction of the required injection amount Qt for air-fuel ratio enrichment is performed, the fuel injection amount and the injection timing by partial lift injection during the compression stroke are changed. Without this, the total amount of the multistage injection can be increased by the amount of the increase correction. Therefore, also in the engine control apparatus of this embodiment, there can exist the same effect as 1st Embodiment.

(Third embodiment)
Next, a third embodiment of the engine control device will be described in detail with reference to FIG. Even in this embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In each of the above embodiments, fuel injection during the rapid warm-up of the catalyst of the engine 10 is performed by fuel injection by full lift injection performed during the intake stroke by the in-cylinder injection valve 37 and during compression stroke by the in-cylinder injection valve 37. The fuel injection is performed through multistage injection with fuel injection by partial lift injection. In the present embodiment, fuel injection during the rapid catalyst warm-up of the engine 10 is performed during fuel injection (port injection) during the intake stroke performed by the port injection valve 25 and during the compression stroke performed by the in-cylinder injection valve 37. The fuel injection is performed through multistage injection. The port injection at this time is performed by full lift injection by the port injection valve 25.

  In this embodiment as well, rotation stabilization control is performed as in the above embodiment. However, the increase in the required injection amount Qt for enriching the air-fuel ratio in the present embodiment is performed in the following manner.

  As shown in FIG. 9, in the present embodiment, when the enrichment is increased, the injection amount of the port injection (port injection amount Qi) is compared to the base time by the amount of increase correction of the required injection amount Qt for enriching the air-fuel ratio. To increase the amount. On the other hand, the injection amount and injection timing of fuel injection by partial lift injection (P / L injection) are maintained at the same amount and timing as at the base time even when the enrichment is increased. For this reason, even in this embodiment, when the enrichment is increased, the total injection amount of the multistage injection is the amount of the increase correction without changing the injection amount and the injection timing of the partial lift injection during the compression stroke from the base time. Increased by minutes. Therefore, also in the engine control apparatus of this embodiment, there can exist the same effect as 1st Embodiment.

  Incidentally, in the present embodiment, the calculation of the port injection amount Qi in the multistage injection at the time of rapid catalyst warm-up is performed in the same manner as the calculation of the F / L injection amount Qf in the multistage injection in the first embodiment. That is, the port injection amount Qi at the base time is calculated by subtracting the P / L injection amount Qp from the required injection amount Qt after calculating the required injection amount Qt and the P / L injection amount Qp. When the enrichment is increased, the port injection amount Qi is calculated by multiplying the calculated value by the increase coefficient Kr.

(Other embodiments)
In addition, the said embodiment can also be changed and implemented as follows.
The calculation of the F / L injection amount Qf in the first embodiment and the port injection amount Qi in the third embodiment at the time of enrichment increase may be performed as follows. First, after calculating the required injection amount Qt from the engine speed NE and the engine load factor KL, the value of the required injection amount Qt is updated to a value obtained by multiplying the calculated value by the increase coefficient Kr. Then, after calculating the P / L injection amount Qp, a value obtained by subtracting the P / L injection amount Qp from the updated requested injection amount Qt is set as the F / L injection amount Qf or the port injection amount Qi. . Even in such a case, the total amount of the injection amounts of the multistage injection can be increased without changing the injection amount and injection timing of the partial lift injection from the base time when the enrichment is increased.

  The additional partial lift injection in the second embodiment may be performed at a time other than the above as long as it does not inhibit other injections. For example, during the compression stroke, the fuel injection may be performed before the fuel injection by the partial lift injection included in the multistage injection, or may be performed during the intake stroke.

-In 2nd Embodiment, although the injection quantity of the additional partial lift injection was made into the same quantity as the injection quantity of the partial lift injection for a base, it is good also as a different quantity.
-In 2nd Embodiment, the frequency | count of the fuel injection by partial lift injection was increased from 1 time of a base time to 2 times at the time of enrichment increase. If the increase for the required increase correction amount is not sufficient, the number of fuel injections by partial lift injection during the enrichment increase may be increased to three or more.

  In the above embodiment, the fuel injection by the full lift injection of the in-cylinder injection valve 37 or the port injection valve 25 is performed only once in the multistage injection at the time of rapid catalyst warm-up, but the fuel injection by such full lift injection is performed a plurality of times. You may make it carry out by dividing | segmenting into.

  In each of the above embodiments, when the catalyst is rapidly warmed up, fuel injection for the required injection amount Qt is performed through multistage injection including fuel injection by partial lift injection. When the deterioration of the combustion state is confirmed, the increase correction of the required injection amount Qt is performed. In addition to the confirmation of the deterioration of the combustion state, the increase correction of the required injection amount Qt may be performed. For example, an increase correction according to the catalyst temperature for protecting the catalyst from overheating, an increase correction for increasing the engine output during acceleration, etc., or an increase correction according to the cooling water temperature for promoting warm-up of the engine 10 And an increase correction according to the retard of the ignition timing. Even in such a case, if the total amount of the multistage injection is increased by the amount of the increase correction without changing the injection amount and the injection timing of the fuel injection by the partial lift injection, the increase correction is performed. It is possible to maintain the combustion improvement effect by partial lift injection.

  In each of the above embodiments, in order to improve the combustion state during rapid catalyst warm-up, multistage injection including fuel injection by partial lift injection is performed. It is conceivable to perform multistage injection including fuel injection by partial lift injection for other purposes. Even in such a case, a small amount of fuel injection realized by partial lift injection is used in a situation where precise injection control is required, and in such a situation, a slight change in the injection amount or injection timing causes the engine to change slightly. This greatly affects the combustion and exhaust properties. Therefore, even in such a case, when the required injection amount Qt is corrected to be increased during the multistage injection including the fuel injection by the partial lift injection, the injection amount and the injection timing of the fuel injection by the partial lift injection are not changed. The total amount of multistage injection may be increased by the amount of increase correction. In such a case, it is possible to maintain the effect of partial lift injection even at the time of increasing correction.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake passage, 11A ... Intake manifold, 12 ... Air cleaner, 13 ... Air flow meter, 14 ... Throttle valve, 15 ... Intake port, 16 ... Cylinder, 16A ... Piston, 17 ... Exhaust passage, 17A ... Exhaust manifold , 18 ... Air-fuel ratio sensor, 19 ... Catalyst device, 20 ... Fuel tank, 21 ... Feed pump, 22 ... Low pressure fuel passage, 23 ... Low pressure fuel pipe, 24 ... High pressure fuel pump, 25 ... Port injection valve, 26 ... High pressure fuel Piping, 27 ... Filter, 28 ... Pressure regulator, 29 ... Fuel gallery, 30 ... Pressure chamber, 32 ... Cam shaft, 33 ... Cam, 34 ... Plunger, 35 ... Electromagnetic spill valve, 36 ... Check valve, 37 ... In-cylinder Injection valve 38 ... Fuel pressure sensor 39 ... Relief passage 39A ... Relief valve 40 ... Electronic control unit 41 Crank angle sensor, 42 ... accelerator pedal sensor, 50 ... housing, 51 ... electromagnetic solenoid, 52 ... fixed core, 53 ... electromagnetic coil, 54 ... movable core, 55 ... valve body, 56 ... spring, 57 ... nozzle body, 58 ... Hole, 59 ... Fuel chamber.

Claims (4)

The required injection amount calculated according to the operating state of the engine is applied as necessary so that the air-fuel ratio of the air-fuel mixture burned in the cylinder becomes a specified target air-fuel ratio when applied to an engine equipped with a fuel injection valve. And an engine control device including an injection control unit that controls the fuel injection valve so as to inject fuel for the required injection amount,
The injection control unit includes fuel injection by partial lift injection that terminates injection before the valve body of the fuel injection valve reaches the fully open position, and full lift injection that terminates injection after the valve body reaches the fully open position. Fuel is injected into the fuel injection valve through multistage injection including both fuel injection ,
When the fuel injection valve performs multi-stage injection of the required injection amount that is increased and corrected to an injection amount that is larger than the required injection amount calculated according to the operating state of the engine, the fuel by the partial lift injection By increasing the fuel injection amount by the full lift injection without changing the injection amount and the injection timing of the injection, the total amount of the multi-stage injection is increased by the amount of the increase correction. Engine control device. The required injection amount calculated according to the operating state of the engine is applied as necessary so that the air-fuel ratio of the air-fuel mixture burned in the cylinder becomes a specified target air-fuel ratio when applied to an engine equipped with a fuel injection valve. And an engine control device including an injection control unit that controls the fuel injection valve so as to inject fuel for the required injection amount,
The injection control unit includes fuel injection by partial lift injection that terminates injection before the valve body of the fuel injection valve reaches the fully open position, and full lift injection that terminates injection after the valve body reaches the fully open position. Fuel is injected into the fuel injection valve through multistage injection including both fuel injection,
When the fuel injection valve performs multi-stage injection of the required injection amount that is increased and corrected to an injection amount that is larger than the required injection amount calculated according to the operating state of the engine, the fuel by the partial lift injection By adding further fuel injection by partial lift injection without changing the injection amount and injection timing of the injection, the total amount of the multi-stage injection is increased by the amount of the increase correction.
An engine control device characterized by that . The injection control unit, during idle operation during cold start of the engine, performs the multi-injection, in the multistage injection, compression stroke by prior notated Rurifuto the partial lift injection and fuel injection during the intake stroke due to the injection The engine control apparatus according to claim 1, wherein the fuel injection is performed. The injection control unit corrects the required injection amount to be increased when deterioration of the combustion state is confirmed.
The engine control apparatus as described in any one of Claims 1-3 .

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