JP2012122438A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control device optimizing exhaust components discharged from each cylinder and improving exhaust performance.SOLUTION: The engine control device includes first fuel injection means 1A, 1B injecting fuel of a first fuel amount in the intake passages 11 of the cylinders 20A, 20B of the multi-cylinder engine, and second fuel injection means 2A, 2B injecting fuel of a second fuel amount towards the insides of the cylinders 20A, 20B. The engine control device further includes a control means 3 controlling temperature increase for controlling the first fuel amount and the second fuel amount to enrich an air-fuel ratio of the first cylinder 20A and simultaneously lean an air-fuel ratio of the second cylinder 20B. In enriching the air-fuel ratio of first cylinder 20A, a first control means 31 of the control means 3 increases the first fuel amount injected from the first fuel injection means 1A.

Description

  The present invention relates to a control device for a multi-cylinder engine that includes a port injection injector that injects fuel in an intake passage and a direct injection injector that injects fuel into a cylinder.

  2. Description of the Related Art Conventionally, as one of exhaust purification control for vehicles equipped with a catalyst device such as an oxidation catalyst or a three-way catalyst on an exhaust passage of an engine (internal combustion engine), the exhaust temperature is raised so as to quickly raise the temperature of the catalyst to the activation temperature. Temperature increase control is known.

  As the temperature rise control, there are those that raise the exhaust temperature by using the oxidation heat of unburned components contained in the exhaust, and those that raise the exhaust temperature by retarding the ignition timing. The former uses the heat of oxidation generated when the carbon component (hydrocarbon HC, carbon monoxide CO, etc.) in the exhaust is oxidized on the catalyst to raise the temperature of the exhaust. In the latter case, the ignition timing is controlled to be retarded from the compression top dead center, the combustion speed in the cylinder is lowered, and the combustion reaction is advanced in the exhaust passage after the exhaust stroke to raise the exhaust temperature. Is. Such temperature increase control is performed, for example, at the time of cold start of the engine, operation in a cold region, or regeneration control of the catalyst device.

  In a multi-cylinder engine having a plurality of cylinders, a technique has been developed for raising the exhaust temperature by making the air-fuel ratio of each cylinder different. For example, Patent Document 1 classifies a plurality of cylinders into two cylinder groups, and controls the exhaust air / fuel ratio of one cylinder group to a rich atmosphere while controlling the exhaust air / fuel ratio of the other cylinder group to a lean atmosphere. Is described. In this bank control, exhaust gas in a rich atmosphere containing carbon components and exhaust gas in a lean atmosphere containing air (oxygen) are simultaneously supplied to the oxidation catalyst to promote the oxidation reaction on the oxidation catalyst, and the catalyst temperature and the exhaust gas. The temperature is rising.

JP 2009-264431 A

  By the way, as a fuel supply injector, an engine having both a port injection injector that injects fuel into an intake port and a direct injection injector that directly injects fuel into a cylinder is known. The port injector is suitable for atomizing the fuel in the intake port and introducing a homogeneous mixture into the cylinder, and the direct injector generates a laminar mixture flow in the cylinder. Therefore, it is suitable for biasing the fuel distribution. By using these two types of fuel supply methods in combination, it is possible to switch between in-cylinder combustion and stratified combustion according to the operating state of the engine, and it is possible to achieve a balance between high output and low fuel consumption. .

  The two types of fuel supply methods described above also affect the exhaust components discharged from the cylinders supplied with fuel by the respective methods. For example, when analyzing exhaust components when increasing the amount of fuel injected from a direct injection injector, it contains not only carbonized components but also particulate matter (PM) with hydrocarbons, sulfates, etc. attached to carbon particles (soot) The amount also increases. On the other hand, when the amount of fuel injected from the port injector is increased, the content of the particulate matter is reduced as compared with the time of fuel injection from the direct injector.

  In other words, even if the amount of fuel introduced into the cylinder is the same amount, the type and amount of components contained in the exhaust gas change if the fuel supply method is different. Therefore, even if the bank control described in Patent Document 1 is applied to an engine having a plurality of fuel supply methods, the ratio of various components contained in the exhaust gas varies depending on the fuel supply method. Therefore, there is a problem that it is difficult to further improve the oxidation reactivity.

One of the purposes of the present case has been invented in view of the above-described problems, and is to optimize exhaust components discharged from each cylinder of a multi-cylinder engine and improve exhaust performance.
The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

(1) An engine control device disclosed herein includes a first fuel injection means for injecting a fuel of a first fuel amount into an intake passage of each cylinder of a multi-cylinder engine, and a first fuel injection device into each cylinder. Second fuel injection means for injecting two fuel amounts of fuel. Further, the first fuel amount and the second fuel amount are controlled to make the air-fuel ratio of the first cylinder of the multi-cylinder engine rich, and at the same time, make the air-fuel ratio of the second cylinder different from the first cylinder lean. Control means for performing the temperature rise control is provided.
The control means includes first control means for increasing the amount of the first fuel supplied to the first cylinder during the temperature rise control. Here, “rich” means that the air-fuel ratio is smaller than stoichiometric (theoretical air-fuel ratio), and “lean” means that the air-fuel ratio is larger than stoichiometric (theoretical air-fuel ratio).

(2) Further, the air-fuel ratio calculated by the control means from the fuel amount obtained by adding the first fuel amount and the second fuel amount supplied to the first cylinder during the temperature increase control becomes rich. In addition, it is preferable to have second control means for controlling the second fuel amount supplied to the first cylinder.
For example, it is conceivable that the second control means decreases the second fuel amount supplied to the first cylinder. If the amount of decrease in the second fuel amount is less than the amount of increase in the first fuel amount, the total air-fuel ratio becomes rich. Thereby, the discharge | emission amount of an unburned liquid component (for example, HC) and a particulate matter (PM) is suppressed.
Further, it is conceivable that the second control means does not change the second fuel amount supplied to the first cylinder. The increase in the first fuel amount is directly reflected in the change in the total air-fuel ratio. Thereby, the control configuration is simplified.
Alternatively, it is conceivable that the second control means increases the second fuel amount supplied to the first cylinder. In this case, the discharge amount of the unburned liquid component (for example, HC) used for the temperature rise control increases.

(3) Moreover, it is preferable that the said control means has a 3rd control means to reduce said 1st fuel amount supplied to a said 2nd cylinder at the time of the said temperature rising control.
(4) Moreover, it is preferable that the said control means has a 4th control means to reduce said 2nd fuel amount supplied to a said 2nd cylinder at the time of the said temperature rising control.

(5) Further, it is preferable that the control means performs the temperature rise control during a compression slur lean operation in which an amount of fuel at which the air-fuel ratio of each cylinder becomes lean is injected in a compression stroke.
The air / fuel ratio “slightly leaner than stoichiometric” here is an air / fuel ratio equal to or higher than the stoichiometric air / fuel ratio, and is preferably an air / fuel ratio in the range of 16 or less, for example. In the compressed light lean operation, the retard amount of the ignition timing can be increased, and the temperature raising efficiency of the exhaust temperature is increased. On the other hand, since the combustion may become unstable when the fuel pressure is low, it is preferable to perform the compression sleek lean operation in a state where the fuel pressure is high (for example, a state where the fuel pressure is equal to or higher than a predetermined fuel pressure).

(6) Further, it is preferable that the second control means maintain the second fuel amount supplied to the first cylinder before and after the temperature increase control is started.
(7) Alternatively, it is preferable that the second control means decreases the second fuel amount supplied to the first cylinder during the temperature rise control. In this case, the decrease amount of the second fuel amount is set to a magnitude smaller than the increase amount of the first fuel amount.

  According to the disclosed engine control device, when the air-fuel ratio of the first cylinder is made rich, by increasing the first fuel amount, the unburned liquid component (for example, It is possible to increase the amount of unburned gas components (for example, CO) while suppressing the discharge amount of HC) and particulate matter (PM). On the other hand, since the air-fuel ratio is controlled to be lean in the second cylinder, an air component (for example, oxygen) in the exhaust can be secured. By these controls, the exhaust component of the engine can be optimized and the exhaust performance can be improved. For example, the temperature of the catalyst interposed in the exhaust passage of the engine can be increased efficiently, and the catalyst can be activated early.

It is a figure which illustrates the block configuration of the control apparatus of the engine which concerns on one Embodiment, and the structure of the engine to which this control apparatus was applied. It is an example of the flowchart performed with this control apparatus. It is an example of the time chart for demonstrating the control content by this control apparatus.

  An engine control apparatus will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment.

[1. Device configuration]
The control device of the present embodiment is applied to a water-cooled multi-cylinder engine 10 (hereinafter simply referred to as the engine 10) shown in FIG. Here, two of the cylinders (cylinders) provided in the multi-cylinder engine 10 are shown, and one is called the first cylinder 20A and the other is called the second cylinder 20B. As shown in FIG. 1, the structures of the first cylinder 20A and the second cylinder 20B are substantially the same, and here, the first cylinder 20A will be mainly described in detail. In FIG. 1, the same reference numerals are used for elements on the second cylinder 20B side that are the same as elements provided on the first cylinder 20A side.

A piston 16 connected to the crankshaft 17 via a connecting rod is fitted in the first cylinder 20A so as to be slidable back and forth. The connecting rod is a link member that converts the reciprocating motion of the piston 16 into the rotational motion of the crankshaft 17.
Around the first cylinder 20A, a water jacket 18 serving as a cooling water flow path is provided. The cooling water is a refrigerant for cooling the engine 10. A cooling water passage 24 is connected to the water jacket 18, and the cooling water circulates inside the water jacket 18 and the cooling water passage 24.

An electric water pump 25 and a radiator 26 are interposed on the cooling water passage 24. The water pump 25 is a variable flow rate pump that is driven at a rotational speed corresponding to an applied voltage and discharges cooling water at a flow rate (flow rate per unit time) corresponding to the rotational speed. The water pump 25 is connected to a battery device (not shown) and operates by receiving power supply from the battery device. Note that the voltage applied to the water pump 25 (the number of rotations of the water pump 25) is controlled by the ECU 3 described later.
The radiator 26 is a heat exchanger that cools the cooling water by exchanging heat between the cooling water and air (for example, outside air introduced from the outside of the vehicle). The heat generated in the engine 10 is transmitted to the cooling water in the water jacket 18 and radiated by the radiator 26.

  An intake port 11 and an exhaust port 12 are connected to the top surface of the combustion chamber on the cylinder head side. An intake valve 14 is provided at the inlet of the intake port 11, and an exhaust valve 15 is provided at the inlet of the exhaust port 12. The intake port 11 and the combustion chamber are communicated or closed by opening and closing the intake valve 14, and the exhaust port 12 and the combustion chamber are communicated or blocked by opening and closing the exhaust valve 15. The upper end portions of the intake valve 14 and the exhaust valve 15 are respectively connected to a rocker shaft (not shown), and are individually reciprocated in the vertical direction by swinging of the rocker shaft.

  A spark plug 13 is provided between the intake port 11 and the exhaust port 12 on the top surface of the combustion chamber. The ignition timing at the spark plug 13 is controlled by the ECU 3. A catalyst device 22 is interposed on the exhaust passage 21 connected to the exhaust port 12. The catalyst device 22 is a catalyst having an oxidizing ability with respect to a carbon component contained in exhaust gas, and includes, for example, a three-way catalyst, an oxidation catalyst, and the like.

  As injectors for supplying fuel to the first cylinder 20A, a port injector 1A for injecting fuel into the intake port 11 and a direct injection injector 2A for injecting fuel directly into the first cylinder 20A are provided. The fuel injected from the port injector 1A is atomized, for example, in the intake port 11, and is introduced into the cylinder in a state of being well mixed with intake air. On the other hand, the fuel injected from the direct injection injector 2A is guided, for example, in the vicinity of the spark plug 13 on a layered air flow formed in the cylinder, and is unevenly distributed in the intake air.

These two types of injectors are also provided in the second cylinder 20B. Hereinafter, the respective injectors related to the fuel supply to the second cylinder 20B are referred to as a port injection injector 1B and a direct injection injector 2B. In addition, when there is no need to clearly indicate a cylinder to be injected with fuel, the reference numerals are simplified and the port injection injector 1 and the direct injection injector 2 are also simply expressed.
The amount of fuel injected from these port injectors 1 and direct injector 2 and the injection timing thereof are controlled by the ECU 3. For example, the control pulse signal is transmitted from the ECU 3 to the injectors 1 and 2 and the injection ports of the injectors 1 and 2 are opened only during a period corresponding to the magnitude of the control pulse signal. In this case, the fuel injection amount is an amount corresponding to the magnitude (drive pulse width) of the control pulse signal.

The port injection injector 1 of each cylinder is connected to the fuel supply path 9 via a low pressure delivery pipe 19A. The low pressure delivery pipe 19A is a tubular passage provided for distributing fuel to the port injector 1 of each cylinder. The direct injection injector 2 of each cylinder is connected to the fuel supply path 9 via the high pressure delivery pipe 19B and the high pressure pump 8. The high pressure delivery pipe 19B is a tubular passage for distributing fuel having a pressure higher than that in the low pressure delivery pipe 19A to the direct injection injector 2 of each cylinder. The pressure of fuel introduced into the direct injection injector 2 (fuel pressure P _HI ) is higher than the pressure of fuel introduced into the port injection injector 1.

The high-pressure pump 8 is a mechanical variable flow rate pump that receives a driving force via a gear (not shown) that is linked to the crankshaft 17 of the engine 10. The high-pressure pump 8 further pressurizes the fuel introduced through the fuel supply path 9 and pumps it into the high-pressure delivery pipe 19B. The pressure feed amount F _{HI of the} fuel discharged from the high pressure pump 8 is variably controlled by the ECU 3.

A feed pump 27 is provided on the upstream side of the fuel supply path 9. The feed pump 27 is an electric or mechanical pump that pumps fuel stored in the fuel tank 23 toward the fuel supply path 9. The pressure of the fuel pumped by the feed pump 27 becomes the pressure of the fuel introduced into the port injector 1. The pressure P _LO and the pumping amount F _LO of the fuel discharged from the feed pump 27 may be substantially constant when the engine 10 is operating, or may be variably controlled by the ECU 3. The feed pump 27 of the present embodiment is a pump that operates by receiving a driving force from the engine 10, similarly to the high-pressure pump 8.
The high-pressure delivery pipe 19B, the fuel pressure sensor 6 that detects the fuel pressure P _HI introduced into direct injector 2 is provided. Wherein information of the detected fuel pressure P _HI is transmitted to ECU 3.

Further, the engine 10 is provided with a crank angle sensor 5 that detects the rotation angle θ _CR of the crankshaft 17. Information regarding the rotation angle θ _CR of the crankshaft 17 detected by the crank angle sensor 5 is transmitted to the ECU 3. Incidentally, it is possible to grasp the engine speed Ne from the variation amount of the rotation angle theta _CR per unit time. Therefore, the crank angle sensor 5 has a function as means for detecting the engine speed Ne of the engine 10. The engine speed Ne may be calculated by the ECU 3 based on the crankshaft rotation angle θ _CR detected by the crank angle sensor 5, or the engine speed Ne may be calculated inside the crank angle sensor 5. Also good.

A water temperature sensor 4 that detects the cooling water temperature W is provided at an arbitrary position on the cooling water passage 24. In addition, an accelerator pedal sensor 7 that detects an operation amount θ _AC corresponding to the depression amount of the accelerator pedal is provided at an arbitrary position of the vehicle on which the engine 10 is mounted. Information on the cooling water temperature W detected by the water temperature sensor 4 and information on the operation amount θ _AC detected by the accelerator pedal sensor 7 are transmitted to the ECU 3.

[2. Control configuration]
[2-1. Control mode]
The ECU 3 (Electronic Control Unit) is an electronic control device that controls the fuel injection amount, fuel supply method, and ignition timing supplied to each cylinder 20A, 20B of the engine 10, for example, a microprocessor or ROM It is configured as an LSI device or an embedded electronic device with integrated RAM. The ECU 3 has four types of operation modes of “MPI mode”, “DI mode”, “compression S / L mode”, and “rich lean mode” as operation modes (control modes) set when the engine 10 is started. (Control mode) is set, and the ECU 3 controls the fuel injection amount, the fuel supply method, and the ignition timing based on each mode.

  The MPI mode is a control mode in which fuel is supplied from the port injector 1 of each cylinder. The fuel pressure required for the fuel injected from the port injector 1 into the intake port 11 is relatively low, that is, even if the fuel pressure introduced into the port injector 1 is relatively low, It is possible to atomize in the intake port 11. Therefore, the MPI mode can be said to be a mode that can be implemented, for example, when starting the engine 10 or during cranking.

The DI mode is a control mode in which fuel is supplied from the direct injection injector 2 of each cylinder. The fuel pressure P _HI required for the fuel injected from the direct injection injector 2 into the cylinders 20A and 20B is relatively high, that is, if the fuel pressure P _HI introduced into the direct injection injector 2 is not relatively high, the injection is performed. It is difficult to stabilize stratified combustion with the generated fuel. Therefore, the DI mode is a mode that is implemented slightly later than the MPI mode, and is performed after the engine 10 is started, for example. In the present embodiment, DI mode is set when the fuel pressure P _HI introduced into direct injector 2 is increased to some extent.

The compression S / L mode is a mode in which a compression sleek lean operation is performed in order to increase the temperature of the exhaust gas early, and the air-fuel ratio is a light lean (a slightly leaner air-fuel ratio than stoichiometric), for example, 14.7 to 16 The ignition timing is significantly retarded while fuel is supplied in the compression stroke from the direct injection injector 2 of each cylinder so that the air / fuel ratio is within a range.
This mode is set to overlap with the DI mode only when the DI mode is set. That is, the compression S / L mode, as in the DI mode, it can be said that the mode with the proviso that the fuel pressure P _HI to direct injector 2 is relatively high. In the present embodiment, the compressed S / L mode is set when the DI mode is already set when a predetermined time has elapsed after the engine 10 is started.

  In the compression S / L mode, fuel is injected in the compression stroke immediately before ignition, and therefore, a portion with a high fuel concentration in the cylinder is likely to be localized in the vicinity of the spark plug 13 (suppresses diffusion of fuel in the cylinder). The ignition timing can be significantly retarded by supplying fuel at an appropriate timing. Further, it is possible to raise the exhaust gas temperature by delaying the ignition timing and causing the combustion reaction to proceed in the exhaust passage after the exhaust stroke (so-called afterburning state). Note that when the combustion speed in the cylinder decreases due to the ignition retard, the tendency of afterburning increases and the exhaust temperature further increases.

  Further, in the compression S / L mode, carbon monoxide (CO), which is an unburned gas component, can remain in the exhaust gas while making the air-fuel ratio lean by stratifying the air-fuel mixture in the cylinder. In this case, since air components (oxygen) that did not contribute to combustion also remain in the exhaust, the oxidation reaction in the catalyst device 22 is promoted, and the exhaust temperature rises. In other words, in the compressed S / L mode, control is performed in which both carbon monoxide and oxygen remain in the exhaust from a single cylinder.

  The rich lean mode is a control mode for increasing the temperature of the exhaust gas earlier, and is a control mode in which the air-fuel ratio is changed for each cylinder of the engine 10 to provide a rich cylinder and a lean cylinder. This mode is set to overlap with the compressed S / L mode only when the compressed S / L mode is set. In the present embodiment, the rich lean mode is set when a predetermined time has elapsed since the compression S / L mode was set. That is, when the compression S / L mode is not set, the rich lean mode is not set.

  In the rich lean mode, the air-fuel ratio of each cylinder is controlled so that carbon monoxide remains in the exhaust exhausted from the rich cylinder and oxygen remains in the exhaust exhausted from the lean cylinder. The That is, in order to further promote the oxidation reaction of carbon monoxide in the compression S / L mode, the cylinder for supplying carbon monoxide to the catalyst device 22 and the cylinder for supplying oxygen are separated from each other. It increases both the amount of carbon monoxide and the amount of oxygen in the exhaust.

  In the present embodiment, since there are two types of fuel supply methods for enriching or leaning the air-fuel ratio of each cylinder, various combinations of which method is applied to which cylinder can be considered. Here, the relationship between the fuel supply method and the exhaust components is shown below. For example, the content of the first line in the table is “HC (hydrocarbon content)” when focusing on the exhaust performance when the injection amount from the “direct injection” injector 2 is increased (riched). "Or" PM (particulate matter content) "is" △ (normal) "," fuel stability "is" ○ (good) ", and" CO (carbon monoxide content) "is Indicates “◎ (excellent)”.

Regarding the symbols in Table 1, the hydrocarbon (HC) and particulate matter (PM), which are unburned liquid components, are expressed as Δ, ○, ◎ in descending order of the content in the exhaust gas. In addition, regarding combustion stability, ◎ indicates that it is more stable than ○, and regarding carbon monoxide (CO), Δ, ○, and ◎ are given in ascending order of content in exhaust gas.

When enriching a certain cylinder, it is considered preferable to increase the injection amount from the direct injection injector 2 when importance is attached to increasing the amount of carbon monoxide contained in the exhaust gas. On the other hand, when it is important to further reduce the amount of hydrocarbons and particulate matter contained in the exhaust gas, it is preferable to increase the injection amount from the port injector 1.
Further, when leaning a certain cylinder, it is considered preferable to reduce the injection amount from the port injector 1 when importance is attached to combustion stability. On the other hand, when it is important to further reduce the amount of hydrocarbons and particulate matter contained in the exhaust gas, it is preferable to reduce the injection amount from the direct injection injector 2.

In the present embodiment, the air-fuel ratio of a certain cylinder is enriched by increasing the amount of fuel injected from the port injector 1, and at the same time, the amount of fuel injected from the direct injection injector 2 is decreased. Control is performed to make the air-fuel ratio lean. For example, when the air-fuel ratio of the first cylinder 20A is enriched and the air-fuel ratio of the second cylinder 20B is made lean, the first cylinder 20A is enriched by increasing the amount of fuel injected from the port injector 1A. The second cylinder 20B is leaned by reducing the amount of fuel injected from the direct injection injector 2B.
Here, the number of cylinders to be enriched or leaned is arbitrary. For example, in the case of a six-cylinder engine, one or two of the six cylinders may be enriched, and the other one or two cylinders may be leaned. You may set and make each rich and lean.

  When the engine 10 is not started, the “normal mode” is set separately from the above four types of modes. This normal mode is a mode that is set when the exhaust gas temperature has risen sufficiently after a certain amount of time has elapsed after the engine 10 is started, or when the vehicle has started running due to an accelerator operation by the driver. . The normal mode is also set when the cooling water temperature W is low and it is difficult to ensure the combustion stability in the control mode such as the compression S / L mode or the rich lean mode. Note that the specific control content in the normal mode is arbitrary, and is appropriately set according to, for example, the operating state of the engine 10 or the traveling state of the vehicle.

[2-2. Control unit]
The ECU 3 includes a mode determination unit 3a, an MPI control unit 3b, a DI control unit 3c, a compression S / L control unit 3d, and a rich lean control unit 3e as software or hardware for performing control in each mode described above. Is provided. A water temperature sensor 4, a crank angle sensor 5, a fuel pressure sensor 6 and an accelerator pedal sensor 7 are connected to the input side of the ECU 3, and the engine speed calculated based on the cooling water temperature W and the rotation angle θ _CR (or the rotation angle θ _CR). Ne), the fuel pressure P _HI, manipulated variable theta _AC information of the accelerator pedal are input. In addition to the port injection injector 1 and the direct injection injector 2, an ignition plug 13, a feed pump 27, a high pressure pump 8, a water pump 25, and the like are connected to the output side of the ECU 3.

The mode determination unit 3a determines the start conditions of the engine 10 and the setting conditions and the setting cancellation conditions for each mode. The conditions determined by the mode determination unit 3a are exemplified below. The setting conditions for the normal mode and the MPI mode are OR conditions, and each mode is set when any of the three types of conditions is satisfied. The normal mode is a mode that is not set to overlap with other modes. Accordingly, the settings of the other modes are canceled when the normal mode is set. On the other hand, each mode other than the normal mode can be set to overlap with other modes other than the normal mode. Information regarding the engine start and control mode set here is transmitted to the MPI control unit 3b, the DI control unit 3c, the compression S / L control unit 3d, and the rich lean control unit 3e.
(1) Start of engine 10-Engine speed Ne has reached a predetermined speed Ne ₀ or more (2) Normal mode-A predetermined start time T _END has elapsed after engine start-An accelerator operation has been performed-Cooling water temperature W is lower than the predetermined temperature W ₀ (3) not in DI mode elapses after the engine start-fuel pressure P _HI is in MPI mode cranking is less than the predetermined pressure P _HI0 predetermined time T _a (4) DI-mode combustion engine after start-up, within the predetermined time T _a, the fuel pressure P _HI becomes a predetermined pressure P _HI0 or more (except for a predetermined period of time T _a <predetermined starting time T _END)
(5) Compression S / L mode ・ After engine startup with DI mode set, a predetermined time T _A has passed and accelerator fully closed (6) Rich lean mode ・ After compression S / L mode starts, two predetermined time T _B has elapsed

  The MPI control unit 3b controls the MPI mode, and has a function of outputting a control pulse signal to the port injection injector 1 of each cylinder to inject fuel into the intake port 11. The magnitude (pulse width) of the control pulse signal output here corresponds to the amount of fuel injected from the port injector 1.

The DI control unit 3c controls the DI mode, and has a function of outputting a control pulse signal to the direct injection injector 2 of each cylinder and injecting fuel into the cylinders 20A and 20B. The magnitude (pulse width) of the control pulse signal output here corresponds to the amount of fuel injected from the direct injection injector 2. Further, DI controller 3c controls the high pressure pump 8 when the engine 10 is started, has a function of raising the fuel pressure P _HI in high-pressure delivery pipe 19B. The start of the engine 10 here means the start of the engine 10 determined by the mode determination unit 3a, and the engine 10 is started when the engine speed Ne becomes equal to or higher than the predetermined speed Ne _0. .

  The compression S / L control unit 3d controls the above-described compression S / L mode, and outputs a control signal to the direct injection injector 2 so that fuel is injected within the compression stroke of each cylinder. have. Further, it has a function of retarding the ignition timing by outputting a control signal to the spark plug 13 of each cylinder.

  The rich lean control unit 3e controls the rich lean control that is performed in the above-described rich lean mode. In the rich lean control, the air-fuel ratio of each cylinder is changed so that the air-fuel ratio of at least one of the cylinders of the engine 10 is enriched and at the same time the air-fuel ratio of at least one other cylinder is leaned. Then, a control signal is output to the port injector 1 and the direct injector 2 of each cylinder. The rich lean control unit 3e includes a rich cylinder MPI control unit 31, a rich cylinder DI control unit 32, a lean cylinder MPI control unit 33, and a lean cylinder DI control unit 34 as software or hardware for performing rich lean control. Is provided.

  The rich cylinder MPI control unit 31 (first control means) is a port provided in the intake port 11 of the cylinder so as to increase the amount of fuel supplied to the cylinder that is enriched by the rich lean control. A control pulse signal is output to the injector 1. That is, the amount of fuel injected from the port injector 1 provided in the intake port 11 of the cylinder to be enriched increases from before the start of rich lean control.

On the other hand, the rich cylinder DI control unit 32 (second control means) applies the direct injection injector 2 provided in the cylinder so as to increase the total amount of fuel supplied to the cylinder to be enriched. In contrast, a control signal pulse is output. That is, the air-fuel ratio calculated from the total fuel amount obtained by summing the fuel amount controlled by the rich cylinder MPI control unit 31 and the fuel amount controlled by the rich cylinder DI control unit 32 is rich. The injection amount from the direct injection injector 2 is controlled. As the setting of the injection amount from the direct injection injector 2, the following three types are conceivable.
(A) Decrease the injection amount from the direct injection injector 2 (B) Do not change the injection amount from the direct injection injector 2 (C) Increase the injection amount from the direct injection injector 2

In the case of (A) above, if the amount of decrease in the injection amount from the direct injection injector 2 is less than the amount of increase in the injection amount in the rich cylinder MPI control unit 31, the total air-fuel ratio becomes rich. In this case, the amount of hydrocarbons and particulate matter discharged into the exhaust is suppressed.
In the case of (B) above, the increment of the injection amount in the rich cylinder MPI control unit 31 is directly reflected in the change of the total air-fuel ratio. This simplifies the control configuration and improves the control accuracy of the air-fuel ratio. Further, the amount of carbon monoxide contained in the exhaust gas is increased as compared with the case of the above (A).
In the case of (C) above, the amount of increase in the injection amount from the direct injection injector 2 is arbitrary in order to make the total air-fuel ratio rich. In this case, the amount of carbon monoxide contained in the exhaust gas increases.
Note that the rich cylinder DI control unit 32 of the present embodiment performs the control (A).

  The lean cylinder MPI control unit 33 (third control means) is a port provided in the intake port 11 of the cylinder so as to reduce the amount of fuel supplied to the cylinder leaned by rich lean control. A control pulse signal is output to the injector 1. That is, the amount of fuel injected from the port injector 1 provided in the intake port 11 of the cylinder to be leaned is reduced from before the start of rich lean control.

  The lean cylinder DI control unit 34 (fourth control means) outputs a control signal pulse to the direct injection injector 2 provided in the cylinder to be leaned. Here, as with the rich cylinder DI control unit 32 described above, three injection amount settings are conceivable. In the present embodiment, the control (A) is performed. When the control (C) is performed, the increase amount of the injection amount from the direct injection injector 2 is set to be smaller than the decrease amount of the injection amount in the lean cylinder MPI control unit 33. As a result, the total air-fuel ratio becomes lean.

[3. flowchart]
FIG. 2 illustrates a flowchart of control executed when the engine 10 is started by the ECU 3 of the present control device. This flow is repeatedly performed inside the ECU 3. Of this flow, steps A1~A30 is mostly elapsed time from the start of the engine 10 corresponding to the control content when it is within the predetermined time T _A. On the other hand, after step A41 corresponding to the control content when a exceeds a predetermined time T _A.

In step A1, the mode determination unit 3a determines whether the elapsed time from the start of the engine 10 is within a predetermined start time _TEND . The start time T _END here is a time until the engine 10 starts to be controlled in the normal mode. Until the present control apparatus is elapsed firing time T _END is after starting the engine 10, the MPI mode or DI mode, the compression S / L mode, rich lean mode is appropriately set corresponding to each mode Control is implemented. Incidentally, the start start time of the engine 10 as a criterion for starting time T _END is determined based on the engine speed Ne.
When the condition of this step is satisfied, the process proceeds to step A2, and when not satisfied, the process proceeds to step A10. Even before the engine 10 is started, the process proceeds to step A2.

In step A2, whether the cooling water temperature W is the predetermined temperature W ₀ or more is determined. The combustion stability in the state coolant temperature W is too low in the cylinder is reduced, wherein the cooling water temperature W is only when the predetermined temperature W ₀ or more, modes other than the normal mode is set. When the condition of this step is satisfied, the process proceeds to step A3, and when not satisfied, the process proceeds to step A10. In step A10, the normal mode is set.

  In step A3, it is determined whether or not cranking of the engine 10 has been completed. If the cranking is not yet started, the process proceeds to step A20. On the other hand, if the engine 10 has already been started and cranking has been completed, the process proceeds to step A4. In step A20, the MPI mode is set, and the MPI control unit 3b controls the port injector 1 of each cylinder.

In step A4, the mode determination unit 3a, the elapsed time from the start of the engine 10 is equal to or within a predetermined time T _A is determined. This condition is one of the DI mode setting conditions. When the condition of this step is satisfied, the process proceeds to step A5, and when not satisfied, the process proceeds to step A41.
In step A5, the mode determination unit 3a, the engine speed Ne is equal to or a predetermined rotational speed Ne ₀ or more is determined. That is, it is determined here whether or not the engine 10 during cranking has been started. When the condition of this step is satisfied, the process proceeds to step A6, and when not satisfied, the process proceeds to step A7.

In step A7, since the engine 10 has not been already started, the pumping quantity F _HI of the high pressure pump 8 at DI controller 3c is set to F _HI = 0, that is, a state where high-pressure pump 8 is stopped. On the other hand, when the routine proceeds to step A6, the engine 10 has already been started and the high pressure pump 8 operates stably, so that the pumping amount F _HI of the high pressure pump 8 is set according to the following equation in the DI control unit 3c. Is done. At this time, cranking of the engine 10 is completed. Further, where the set pumping quantity F _HI control signal is output to the high-pressure pump 8 as ejected. Accordingly, the fuel pressure P _HI introduced into direct injector 2A, 2B is increased.
(Pressure feed amount F _HI of the high-pressure pump 8) = (Pressure feed amount F _LO of the feed pump 27) − (fuel injection amount) −α

The “fuel injection amount” in this equation is the total amount of fuel injected from the port injector 1 and the direct injector 2. In the MPI mode, it is synonymous with the amount of fuel injected from the port injector 1.
In step A8, the mode determination unit 3a, whether the fuel pressure P _HI is the predetermined pressure P _HI0 or not is determined. When the condition of this step is satisfied, the process proceeds to step A30 and the DI mode is set. In this case, the direct injection injector 2 is controlled by the DI control unit 3c in parallel with the control of the port injection injector 1 by the MPI control unit 3b. When the condition of step A8 is not satisfied, the process proceeds to step A20 and the MPI mode is continued.

When the elapsed time from the start of the engine 10 exceeds a predetermined time T _A, control proceeds from step A4 to step A41. In step A41, the mode determination unit 3a determines whether the DI mode is set at that time. That Here, the elapsed time from the start of the engine 10 whether the fuel pressure P _HI rises to a predetermined pressure P _HI0 or when within a predetermined time T _A is determined. When the condition of this step is satisfied, the process proceeds to step A42, and when not satisfied, the process proceeds to step A70. In step A70, the MPI mode is continued, and the DI mode and the subsequent compression S / L control are not performed.

In step A42, the mode determination unit 3a determines whether or not the accelerator opening is fully closed (for example, the accelerator pedal operation amount θ _AC is θ _AC ≈0). If the accelerator operation is performed here, the process proceeds to step A80, and the normal mode is set. On the other hand, if there is no accelerator operation, the process proceeds to step A50, and the compression S / L mode is set. In the compression S / L mode, the direct injection injector 2 and the spark plug 13 are controlled by the compression S / L control unit 3d in parallel with the control of the port injection injector 1 by the MPI control unit 3b. That is, a control signal is output to the direct injection injector 2 so that fuel is injected within the compression stroke of each cylinder, and a control signal is output to the spark plug 13 of each cylinder so as to retard the ignition timing. .

In step A51 subsequent, in the mode determining unit 3a, after the start of the compression S / L mode, whether or not the second predetermined time T _B has elapsed is determined. When the condition for this step is satisfied, the routine proceeds to step A60, where the rich lean mode is set.
In this case, at least one cylinder to be enriched and leaned is set by the rich lean control unit 3e, and a control signal is output to the port injector 1 and the direct injector 2 provided in those cylinders. Is done.

Note that the port injection injector 1 and the direct injection injector 2 provided in the cylinders that are not targeted for enrichment and leaning may be controlled by the MPI control unit 3b and the compression S / L control unit 3d.
On the other hand, if the condition of step A51 is not satisfied, the flow ends. Thus, the second predetermined time T _B is reserved as a time compression S / L control is performed. In other words, rich lean control is performed when the duration of the compression S / L control exceeds a second predetermined time T _B.

[4. Action]
FIG. 3 shows the setting state of the operation mode and the variation with time of various parameters related to the engine 10 when the control is executed according to the above flowchart when the engine 10 is started in the vehicle on which the engine 10 is mounted.
When the ignition switch of the vehicle is operated at time t ₀ , cranking of the engine 10 by a starter (not shown) is started. As a result, the pressure P _{LO of the} fuel discharged from the feed pump 27 rises while pulsating according to the engine speed Ne, and the fuel pressure P _LO in the low pressure delivery pipe 19A introduced into the port injection injector 1 is secured. .

At this time, if the coolant temperature W is equal to or higher than the predetermined temperature W ₀ , the MPI mode is set in the mode determination unit 3a of the ECU 3, and the port injection injector 1 of each cylinder is controlled by the MPI control unit 3b. Thus, the control pulse signal input to the port injection injector 1 (drive pulse width) is increased at time t _1, fuel injection into the intake port 11 of each cylinder is started. Since the still high pressure pump 8 at this time is not operating, the fuel pressure P _HI in high-pressure delivery pipe 19B is substantially the same value as the fuel pressure P _LO in the low-pressure delivery pipe 19A.

Gradually increases the engine speed Ne, the time t ₂ becomes equal to or higher than a predetermined rotational speed Ne _0, the engine 10 in the mode determining portion 3a is determined to have started. The time t ₂ corresponds to the elapsed time measurement start time according to the setting condition of the normal mode and compression S / L mode. At this time, a control signal is output from the DI control unit 3c to the high-pressure pump 8, and the high-pressure pump 8 is driven. Accordingly, the pumping quantity F _HI of the fuel discharged from the high-pressure pump 8 is increased at time t ₂ after the fuel pressure P _HI in high-pressure delivery pipe 19B is increased. Further, when the engine 10 is started, the exhaust heat moves to the exhaust passage 21 and the catalyst device 22, and the catalyst temperature gradually rises.

When the fuel pressure P _HI becomes a predetermined pressure P _HI0 above time t _3, DI mode is set in the mode determining unit 3a, direct injector 2 of each cylinder is controlled to DI controller 3c. Thus, the control pulse signal input to the direct injector 2 (drive pulse width) is increased at time t _3, the fuel injection into each cylinder is started.
At time t ₄ when from time t ₂ a predetermined time T _A has passed, the mode determination unit compression S / L mode is set in 3a, direct injector 2 and the ignition plug 13 of each cylinder compression S / L control unit 3d To be controlled. That is, the timing of fuel injection from the direct injection injector 2 is changed so as to be completed within the compression stroke of each cylinder, and the ignition timing is changed in the retarding direction.

In the compression S / L mode, the exhaust gas temperature increases with ignition retard. Further, since carbon monoxide and oxygen are present in the exhaust, the oxidation reaction in the catalyst device 22 is promoted. Accordingly, the catalyst temperature of the compressed S / L mode is set time t ₄ after further increased, the catalyst is activated early. The time t ₄ corresponds to the measurement start time of the elapsed time according to the setting condition of the rich lean mode.

From time t ₄ when the second predetermined time T _B at time t ₅ has elapsed, the rich lean mode is set in the mode determination unit 3a. In response to this, the rich lean control unit 3e performs rich lean control that enriches the air-fuel ratio of at least one of the cylinders of the engine 10 and at the same time leans the air-fuel ratio of the other cylinders. Here, an example will be described in which the cylinder to be enriched is the first cylinder 20A and the cylinder to be leaned is the second cylinder 20B.

  The rich cylinder MPI control unit 31 outputs a control pulse signal to the port injector 1A on the first cylinder 20A side to increase the fuel injection amount from the port injector 1A. On the other hand, the rich cylinder DI control unit 32 outputs a control pulse signal to the direct injection injector 2A on the first cylinder 20A side, and decreases the fuel injection amount from the direct injection injector 2A. However, since the air-fuel ratio calculated from the total fuel injection amount must be rich, the decrease amount of the fuel injection amount in the direct injection injector 2A is smaller than the increase amount of the fuel injection amount in the port injection injector 1A. Amount.

  Further, the lean cylinder MPI control unit 33 outputs a control pulse signal to the port injector 1B on the second cylinder 20B side, and decreases the fuel injection amount from the port injector 1B. Similarly, the lean cylinder DI control unit 34 outputs a control pulse signal to the direct injection injector 2B on the second cylinder 20B side, and decreases the fuel injection amount from the direct injection injector 2B. This ensures that the total air-fuel ratio is lean.

  By the rich lean control described above, the amount of carbon monoxide contained in the exhaust discharged from the rich-side first cylinder 20A increases, and the content of hydrocarbons and particulate matter decreases. On the other hand, the content of hydrocarbons and particulate matter also decreases with respect to the exhaust discharged from the lean-side second cylinder 20B. In addition, combustion stability is improved despite a large amount of oxygen remaining in the exhaust.

The exhaust discharged from the first cylinder 20A and the exhaust discharged from the second cylinder 20B merge in the exhaust passage 21, and are introduced into the catalyst device 22. In the catalyst device 22, the oxidation reaction is promoted by the carbon monoxide contained in the exhaust on the first cylinder 20A side and the oxygen contained in the exhaust on the second cylinder 20B side. Thus, the rising slope of the after time t ₅ of the catalyst temperature rich lean control is performed further increases, the catalyst is more activated early.
Note that when the predetermined start time T _END from the time t ₂ when the engine 10 is started reaches the time t ₆ , the mode determination unit 3a sets the normal mode. As a result, the MPI mode, DI mode, compression S / L mode, and rich lean mode are terminated, and normal control of the engine 10 is performed.

[5. effect]
In the above control device, for example, when the air-fuel ratio of the first cylinder 20A is made rich during rich lean control, control is performed to increase the amount of fuel injected from the port injector 1A. Thereby, compared with the case where enrichment is achieved by increasing the amount of fuel injected from the direct injection injector 2A, the amount of carbon monoxide is increased while suppressing emissions of hydrocarbons and particulate matter. be able to. On the other hand, since the air-fuel ratio of the second cylinder 20B is controlled to be lean, oxygen in the exhaust can be secured. As a result, exhaust components can be optimized and the exhaust performance of the engine 10 can be improved. Moreover, the oxidation reactivity in the catalyst device 22 can be improved, the catalyst temperature can be increased efficiently, and early activation of the catalyst can be achieved.

  Further, in the above control device, the amount of fuel injected from the direct injection injector 2A is reduced so that the air-fuel ratio of the first cylinder 20A becomes rich in total. That is, the rich cylinder DI control unit 32 selects the setting (A) from the three injection amount settings (A) to (C). Thereby, as shown in Table 1, there exists an advantage that the discharge | emission amount of the hydrocarbon and particulate matter in exhaust_gas | exhaustion can be suppressed.

  When the setting of (B) is selected, as shown in Table 1, the amount of carbon monoxide in the exhaust gas can be increased as compared with the case of selecting the setting of (A). There is an advantage that the oxidation reaction can be promoted. Further, since it is not necessary to change the amount of fuel injected from the direct injection injector 2A, the increment of the fuel injected from the port injection injector 1A is reflected as it is in the total air-fuel ratio in the first cylinder 20A. The configuration can be simplified.

Alternatively, when the setting of (C) is selected, the amount of carbon monoxide in the exhaust gas can be increased further than when the setting of (A) or (B) is selected, and the oxidation reaction in the catalyst device 22 can be performed. Can be promoted.
If the above settings (A) to (C) can be selected at any time, it is possible to adjust the ratio of components contained in the exhaust from the first cylinder 20A, and according to the driving state of the vehicle. Flexible temperature rise control becomes possible. Therefore, the rich cylinder DI control unit 32 may select any one of the settings (A) to (C) based on various parameters related to the engine 10. In this case, the rich cylinder DI control unit 32 controls the injection amount of the direct injection injector 2 provided in the cylinder so as to increase the total amount of fuel supplied to the cylinder at least for the cylinder to be enriched. Anything to do.

  Further, in the above control device, when the air-fuel ratio of the second cylinder 20B is made lean, control is performed to reduce the amount of fuel injected from the port injector 1B. As a result, as shown in Table 1, oxygen in the exhaust gas is secured while improving combustion stability as compared with the case where lean is achieved by reducing the amount of fuel injected from the direct injection injector 2B. can do. Therefore, the catalyst temperature of the catalyst device 22 can be increased efficiently, and the catalyst can be activated early.

  Further, in the above control device, not only the amount of fuel injected from the port injector 1B but also the amount of fuel injected from the direct injector 2B is reduced. Thereby, as shown in Table 1, it is possible to secure oxygen in the exhaust gas while suppressing the discharge amount of hydrocarbons and particulate matter into the exhaust gas. Therefore, it is possible to achieve both improvement in exhaust performance and early activation of the catalyst device 22.

  In the control device described above, the rich lean mode is set to overlap with the compressed S / L mode only when the compressed S / L mode is set. That is, in the present embodiment, the compression light lean operation and the rich lean control are performed in an overlapping manner. The rich lean control acts to further increase the amount of a component that promotes the oxidation reaction in the catalyst device 22 such as carbon monoxide and oxygen generated in the exhaust gas in the compression / slight lean operation. Therefore, by applying the rich lean control to the compression slight lean operation, the temperature increase effect achieved by the compression slight lean operation can be further amplified, and the exhaust temperature can be raised extremely efficiently and quickly. It becomes possible.

  Further, in the rich lean control described above, as shown in Table 1, it is possible to select an optimal combination of the control target and the control content according to the target exhaust characteristics and combustion stability. That is, as compared with the case where only the compression sleek lean operation is performed, not only the additional effects as shown in Table 1 can be provided, but also a combination of these additional effects can be arbitrarily set. Control diversity can be preserved.

[6. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.
In the control device described above, the ECU 3 having various modes such as the normal mode, the MPI mode, the DI mode, and the compression S / L mode is exemplified as the control mode when starting the engine 10, but these control modes are described above. It is not an essential element for the control device.

Further, the setting conditions for each mode are not limited to those described in the above-described embodiment, and the setting conditions may be determined using a plurality of other parameters. As other specific parameters, intake flow rate, intake manifold pressure (intake pressure), supercharging pressure (turbo pressure), intake air temperature (supply air temperature), outside air temperature, vehicle speed, and the like may be used.
In the embodiment described above, when the compression S / L mode has passed the second predetermined time T _B after being set rich lean mode is set, the rich lean control to be performed on the rich lean mode The exhaust temperature can be raised by the control alone, and it may be performed independently without depending on the setting of other control modes.

1,1A, 1B Port injection injector (first fuel injection means)
2,2A, 2B Direct injection injector (second fuel injection means)
3 ECU (control means)
3a Mode determination unit 3b MPI control unit 3c DI control unit 3d Compression S / L control unit 3e Rich lean control unit 31 Rich cylinder MPI control unit (first control means)
32 Rich cylinder DI controller (second control means)
33 Lean cylinder MPI controller (third control means)
34 Lean cylinder DI controller (fourth control means)
4 Water temperature sensor 5 Crank angle sensor 6 Fuel pressure sensor 7 Accelerator pedal sensor 10 Engine 20A First cylinder 20B Second cylinder 22 Catalytic device

Claims (7)

First fuel injection means for injecting fuel of a first fuel amount into the intake passage of each cylinder of the multi-cylinder engine;
Second fuel injection means for injecting a second fuel amount of fuel into each cylinder;
By controlling the first fuel amount and the second fuel amount, the air-fuel ratio of the first cylinder of the multi-cylinder engine is made rich, and at the same time, the air-fuel ratio of the second cylinder different from the first cylinder is made lean. Control means for performing temperature control,
The control means is
An engine control device comprising first control means for increasing the amount of the first fuel supplied to the first cylinder during the temperature rise control. The control means is
Supplied to the first cylinder so that the air-fuel ratio calculated from the sum of the first fuel amount and the second fuel amount supplied to the first cylinder during the temperature increase control becomes rich. 2. The engine control device according to claim 1, further comprising second control means for controlling the second fuel amount. The control means is
3. The engine control device according to claim 1, further comprising a third control unit configured to reduce the amount of the first fuel supplied to the second cylinder during the temperature increase control. 4. The control means is
The engine control device according to any one of claims 1 to 3, further comprising fourth control means for reducing the amount of the second fuel supplied to the second cylinder during the temperature rise control. . 5. The control unit performs the temperature increase control during a compression slur lean operation in which a fuel amount in which the air-fuel ratio of each cylinder is slightly leaner than the stoichiometric injection is injected in a compression stroke. The engine control device according to any one of the above. The engine control device according to claim 2, wherein the second control means maintains the second fuel amount supplied to the first cylinder before and after starting the temperature raising control. The engine control device according to claim 2, wherein the second control means reduces the second fuel amount supplied to the first cylinder during the temperature rise control.

Images