JP5831160B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a multi-cylinder internal combustion engine that performs in-cylinder injection.

  Conventionally, as one of the exhaust purification control of a vehicle provided with a catalyst device such as a three-way catalyst and an oxidation catalyst on an exhaust passage of an engine (internal combustion engine), an increase in the exhaust temperature is performed so as to quickly raise the catalyst temperature to the activation temperature. Temperature control is known. This temperature raising control includes 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 components (hydrocarbon, carbon monoxide, etc.) in the exhaust are oxidized on the catalyst to raise the temperature of the exhaust. As this type of technology, unburned liquid components (hydrocarbons) and unburned gas components (carbon monoxide) remain in the exhaust discharged from the cylinder by controlling the timing of fuel injection and the combustion mode. Technology is known. There is also a technique for adding hydrocarbons directly into the exhaust by adding a fuel addition valve on the exhaust passage.

  However, these technologies require fuel and additives that are consumed by the oxidation reaction on the catalyst, in addition to the fuel required to rotate the engine. Furthermore, in order to oxidize the carbon component in the exhaust gas on the catalyst, the catalyst temperature must reach a predetermined activation temperature. That is, when the catalyst is not sufficiently warmed, it is necessary to raise the temperature of the catalyst using another method.

  On the other hand, the latter controls the ignition timing to the retarded (retarded) side from the compression top dead center, and causes the combustion reaction to proceed in the exhaust passage after the exhaust stroke (so-called afterburning state). Is to raise. When the combustion speed in the cylinder decreases due to the retard of the ignition timing, the tendency of afterburning increases and the exhaust temperature increases. In this case, it is possible to raise the exhaust temperature without depending on the oxidation reaction on the catalyst.

  In addition to the ignition retard control as described above, a technique for raising the temperature of exhaust gas by setting the fuel injection timing into the cylinder within the compression stroke is also known. If the fuel is injected into the cylinder in the compression stroke immediately before ignition, it is easy to suppress the diffusion of the fuel in the cylinder, and it becomes easy to localize a portion having a high fuel concentration in the cylinder in the vicinity of the spark plug. As a result, the ignition timing can be significantly retarded, and the exhaust temperature further increases. As a technique for performing ignition retard control while injecting fuel in a cylinder in a compression stroke, for example, a technique described in Patent Document 1 is known.

JP 2004-197674 A

However, considering the combustion stability in the cylinder of the engine, the retard amount of the ignition timing is limited, and it is difficult to further increase the temperature rise rate of the exhaust gas. On the other hand, in recent years, environmental performance required for engines and exhaust gas purification performance required for vehicles have been advanced, and a new method for activating the catalyst at an earlier stage is being sought.
One of the objects of the present case was invented in view of the above-described problems, and is to improve the temperature raising performance of exhaust gas regarding a control device for an internal combustion engine.
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) A control device for an internal combustion engine disclosed herein is a control device for a multi-cylinder internal combustion engine that performs in-cylinder injection. First, a fuel injection control means for performing fuel injection into each cylinder of the internal combustion engine in a compression stroke is provided. Further, the ignition timings of all cylinders are retarded during fuel injection by the fuel injection control means, and the ignition timings of some cylinders whose ignition sequence is not continued after a predetermined period from the start of the fuel injection are set to the ignition timings of other cylinders. Ignition control means for retarding is provided.
That is, when controlling the ignition timing, the ignition timing of all the cylinders is retarded, and the retard amount for the cylinders where the ignition timing is not continuous is increased as compared with the other cylinders.
Here, “a part of cylinders whose ignition order is not continuous” may be one of a plurality of cylinders or a plurality of cylinders. When the number of cylinders to be retarded is one, the firing order is not continuous regardless of which cylinder is selected. Further, when a plurality of cylinders are retarded, any combination may be selected from combinations of cylinders whose ignition order is not continuous.

(2) Moreover, it is preferable to provide the water temperature detection means which detects the cooling water temperature of the said internal combustion engine. In this case , it is preferable that when the cooling water temperature detected by the water temperature detection means is equal to or lower than a predetermined water temperature, the fuel injection control means performs fuel injection into each cylinder of the internal combustion engine in a compression stroke .
That is, when retarding the ignition timing of the cylinders whose ignition order is not continuous from the ignition timing of the other cylinders, it is preferable to detect and determine “the internal combustion engine has started cold” using the coolant temperature as an index .

  (3) Moreover, it is preferable to provide a catalyst temperature detecting means for detecting the temperature of the catalyst device provided in the exhaust system of the internal combustion engine. In this case, the ignition control means sets the ignition timing of some of the cylinders from the ignition timings of the other cylinders when the catalyst temperature is equal to or lower than a predetermined value after a lapse of a predetermined time from the ignition timing retard of all the cylinders. It is preferable to retard.

(4) Moreover, it is preferable to provide the load control means which controls the magnitude | size of the load of the said internal combustion engine based on the cooling water temperature of the said internal combustion engine. In this case, the load control means, when the cooling water temperature from retarding the ignition timing of all the cylinders is detected after a predetermined time has elapsed following the second predetermined temperature lower than a predetermined temperature, to increase the load preferable. For example, in addition to the above retard control, it is preferable to operate an air conditioner or an alternator.

  (5) Further, the internal combustion engine has a plurality of cylinders arranged in a row, and the ignition control means retards the ignition timing of cylinders arranged at least other than the end portion among the plurality of cylinders. Is preferred. That is, it is preferable that the target cylinder of the retard is a cylinder arranged inside the cylinder block (a position other than the end portion). When the number of cylinders to be retarded is plural, it is preferable that at least one cylinder is disposed inside. More preferably, all the cylinders are arranged inside.

  According to the disclosed control device for an internal combustion engine, by increasing the ignition timing of some cylinders whose ignition order is not continuous more than other cylinders, the exhaust flow rate can be increased while ensuring the rotational stability of the internal combustion engine. And the temperature raising performance of the exhaust can be improved.

It is a figure which illustrates the block configuration of the control apparatus of the internal combustion engine which concerns on one Embodiment, and the structure of the engine to which this control apparatus was applied. It is a schematic diagram which shows arrangement | positioning of each cylinder of the internal combustion engine of FIG. It is a flowchart regarding selection of the fuel injection mode implemented with the control apparatus of FIG. It is a flowchart regarding selection of the ignition mode implemented with the control apparatus of FIG. It is a flowchart regarding the load increase control implemented with the control apparatus of FIG. It is a time chart for demonstrating the control effect | action by the control apparatus of FIG. It is a time chart for demonstrating the control effect | action by the control apparatus of FIG.

  A control apparatus for an internal combustion engine 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. In addition, each configuration of the following embodiment can be selected as necessary, or may be appropriately combined, and various modifications can be made without departing from the spirit of the embodiment.

[1. Device configuration]
[1-1. engine]
The control apparatus of this embodiment is applied to the water-cooled engine 10 (internal combustion engine) shown in FIGS. The engine 10 is an in-line four-cylinder engine as shown in FIG. 2, and four cylinders 20 (cylinders) are arranged in series when the cylinder block 30 is viewed from the cylinder head side. Hereinafter, when describing each of the cylinders 20 arranged in a row, the first cylinder 20a, the second cylinder 20b, the third cylinder 20c, and the fourth cylinder 20d are arranged in order from the end of the cylinder block 30. Call it. The first cylinder 20a and the fourth cylinder 20d are arranged at both ends in the row direction, and the second cylinder 20b and the third cylinder 20c are sandwiched between the first cylinder 20a and the fourth cylinder 20d inside the row. It is arranged at the inner position. FIG. 1 shows a cross section of any one of these cylinders 20.

As shown in FIG. 1, a piston 19 connected to a crankshaft 21 via a connecting rod is fitted in the cylinder 20 so as to be slidable back and forth. The connecting rod is a link member that converts the reciprocating motion of the piston 19 into the rotational motion of the crankshaft 21.
Further, a water jacket 23 serving as a cooling water flow path is provided around the cylinder 20. A cooling water passage 24 is connected to the water jacket 23, and cooling water circulates inside the water jacket 23 and the cooling water passage 24.

  The water jacket 23 is connected along the outer periphery of the four cylinders 20a to 20d. The first cylinder 20a and the fourth cylinder 20d are surrounded by the water jacket 23 over almost the entire circumference except for the portion facing one adjacent cylinder, and the cooling performance is good. On the other hand, since each of the second cylinder 20b and the third cylinder 20c is adjacent to the two cylinders 20, the temperature of the cylinder liner is less likely to be lower than that of the first cylinder 20a and the fourth cylinder 20d, and the heat retention is good. .

As shown in FIG. 1, a 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 discharges cooling water at a flow rate corresponding to the number of rotations. A battery (not shown) is connected to the water pump 25 and operates by receiving power from the battery.
The radiator 26 is a heat exchanger that cools the cooling water by causing heat exchange 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 23, and the heat of the cooling water is radiated by the radiator 26.

[1-2. Intake and exhaust system]
An intake port 13 and an exhaust port 14 are connected to the ceiling surface of the cylinder 20. An intake valve 15 is provided at the opening of the intake port 13 on the cylinder 20 side, and an exhaust valve 16 is provided at the exhaust port 14. When the intake valve 15 is opened and closed, the intake port 13 and the internal space (combustion chamber) of the cylinder 20 are communicated or closed, and when the exhaust valve 16 is opened and closed, the exhaust port 14 and the internal space of the cylinder 20 are communicated or closed. Is done.

  A spark plug 17 is provided between the intake port 13 and the exhaust port 14 with its tip protruding inside the cylinder 20. One spark plug 17 is provided for each of the four cylinders 20a to 20d. Hereinafter, as shown in FIG. 2, the spark plugs 17 of the first cylinder 20a to the fourth cylinder 20d will be described with reference numerals 17a to 17d. The timing of ignition by these spark plugs 17a to 17d is individually controlled by the engine control device 1 described later.

  Further, as shown in FIG. 2, intake manifolds 27 (intake manifolds, intake manifolds) are connected upstream of the intake ports 13 connected to the cylinders 20 of the engine 10, and exhaust manifolds are connected downstream of the exhaust ports 14. 28 (exhaust manifold, exhaust manifold) is connected. Further, as shown in FIG. 1, a catalyst device 22 is interposed in the exhaust passage 18 further downstream of the exhaust manifold 28 than the exhaust manifold 28. The catalyst device 22 is for purifying various components contained in the exhaust, and is, for example, a three-way catalyst, an oxidation catalyst, a NOx purification catalyst, or a DPF.

[1-3. Fuel injection system]
In the engine 10, two types of injectors are provided in each cylinder 20. One is a direct injection injector 11 (in-cylinder injection valve) that directly injects fuel into the cylinder 20, and the other is a port injection injector 12 (port injection valve) that injects fuel into the intake port 13. is there. Injecting fuel from the direct injector 11 is called “DI injection”, and injecting fuel from the port injector 12 is called “PI injection”.

  The fuel injected from the direct injection injector 11 is guided in the vicinity of the spark plug 17 on a layered air flow formed in a cylinder, for example, and is unevenly distributed in the intake air. On the other hand, the fuel injected from the port injector 12 is atomized in, for example, the intake port 13 and introduced into the cylinder 20 in a state of being well mixed with intake air. In general, the fuel pressure of the fuel injected from the port injection injector 12 is lower than the fuel pressure of the fuel injected from the direct injection injector 11.

  The amount of fuel injected from these two types of injectors 11 and 12 and the injection timing thereof are controlled by the engine control device 1. Specifically, a control pulse signal is transmitted from the engine control device 1 to the injectors 11 and 12, and the injection ports of the injectors 11 and 12 are opened only during a period corresponding to the magnitude of the control pulse signal. Accordingly, the fuel injection amount becomes an amount corresponding to the magnitude (drive pulse width) of the control pulse signal, and the injection timing corresponds to the time when the control pulse signal is transmitted.

  Hereinafter, as shown in FIG. 2, the direct injection injector 11 provided in each of the first cylinder 20 a to the fourth cylinder 20 d will be described with reference numerals 11 a to 11 d. The timing of fuel injection by these direct injection injectors 11 a to 11 d is individually controlled by the engine control device 1. In addition, although the port injection injector 12 of each cylinder is also individually controlled by the engine control apparatus 1, in this embodiment, DI injection mainly by the direct injection injectors 11a to 11d will be described in detail.

[1-4. Sensor system]
A cooling water temperature sensor 5 (water temperature detecting means) for detecting the cooling water temperature W is provided at an arbitrary position on the cooling water passage 24. The coolant temperature W is used, for example, to determine whether or not the engine 10 is in a cold start state. Information on the coolant temperature W detected here is transmitted to the engine control device 1.
In the vicinity of the catalyst device 22, a catalyst temperature sensor 6 (catalyst temperature detecting means) for detecting the catalyst temperature C is provided. Although FIG. 1 illustrates the catalyst temperature sensor 6 provided on the upstream side of the catalyst device 22, the catalyst temperature sensor 6 may be provided on the downstream side of the catalyst device 22. The catalyst temperature C detected by the catalyst temperature sensor 6 serves as an index for determining the activity of the catalyst device 22. Information on the catalyst temperature C detected here is transmitted to the engine control device 1.

  An accelerator opening sensor 7 for detecting an accelerator opening P corresponding to the depression amount of the accelerator pedal is provided at an arbitrary position of the vehicle. The accelerator opening P is a parameter corresponding to a driver's start request or acceleration request, that is, corresponds to an output request to the engine 10. Note that the accelerator opening P is substantially zero during idling immediately after the engine 10 is started. Information on the accelerator opening P detected here is transmitted to the engine control apparatus 1.

The engine 10 is provided with a crank angle sensor 8 that detects the rotation angle θ of the crankshaft 21. Information regarding the rotation angle θ of the crankshaft 21 detected by the crank angle sensor 8 is transmitted to the engine control device 1. Note that the amount of change in the rotation angle θ per unit time corresponds to the engine speed Ne. Therefore, the crank angle sensor 8 has a function as means for detecting the engine speed Ne of the engine 10. The engine speed Ne may be calculated by the engine control device 1 based on the rotation angle θ of the crankshaft, or may be calculated inside the crank angle sensor 8.
A vehicle speed sensor 9 that detects the speed of the host vehicle (vehicle speed V) is provided at an arbitrary position of the vehicle. Information on the vehicle speed V detected here is transmitted to the engine control device 1.

[2. Control configuration]
[2-1. Control mode]
The engine control device 1 is an electronic control device that comprehensively controls the fuel injection amount, the fuel supply method, the ignition timing, and the like supplied to the cylinders 20a to 20d of the engine 10, for example, a microprocessor, ROM, RAM Etc. are configured as LSI devices or embedded electronic devices.
In the engine control device 1, two modes, “normal injection mode” and “compression S / L mode”, are set as fuel injection control modes when the engine 10 is started. Three types of modes are set: ignition mode, retard mode, and additional retard mode.

The normal injection mode is a mode in which a fuel injection method other than “DI injection in the compression stroke” is performed, and is, for example, a control mode in which DI injection or PI injection is performed in the intake stroke. In this mode, during cranking for starting the engine 10, a transition period from when the engine 10 is started until the engine speed Ne is stabilized, after a predetermined time T _END has elapsed after the engine 10 is started (exhaust temperature or For example, during idling operation in which the catalyst temperature C is sufficiently warm).
This normal injection mode is also selected when the accelerator operation is performed by the driver and the vehicle starts to travel or when the engine 10 is not idling. The specific control content in the normal injection mode is arbitrary, and for example, DI injection and PI injection may be appropriately set according to the operating state of the engine 10 and the traveling state of the vehicle.

On the other hand, the compression S / L mode is a fuel injection mode in which DI injection is performed in the compression stroke in order to raise the exhaust gas temperature early after the engine 10 is started. This mode is selected after the engine 10 is started and when the engine speed Ne is stable (after a predetermined time T _STA has elapsed since the engine start). In the present embodiment, the compression S / L mode execution condition is further added, and is selected at the time of cold start where the cooling water temperature W is equal to or lower than the predetermined water temperature W ₀ .
In this compression S / L mode, the direct injection injectors 11a to 11a of each cylinder are set so that the air-fuel ratio is slightly lean (the air-fuel ratio is slightly leaner than stoichiometric, for example, the air-fuel ratio in the range of 14.7 to 16). Fuel is supplied in the compression stroke from 11d.

Next, the ignition timing control will be described in detail.
The normal ignition mode is a normal mode in which the ignition timing is set according to the output and load required for the engine 10, and is selected when the fuel injection mode is the normal injection mode. The specific control content in the normal ignition 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. On the other hand, when the fuel injection mode is the compression S / L mode, one of the retard mode and the additional retard mode is selected.

The retard mode is a mode in which the ignition timing is controlled in the retard direction (retarding direction) as compared with the normal ignition mode, and is selected when the fuel injection mode becomes the compression S / L mode. In this retard mode, the ignition timing at the spark plugs 17a to 17d of each cylinder is controlled so as to retard as compared with that in the normal ignition mode.
In the above-described compression S / L mode, fuel is injected in the compression stroke immediately before ignition, and therefore, a portion where the fuel concentration is high in the cylinder is likely to be localized near the spark plug 17 (in the cylinder of the fuel). By supplying the fuel at an appropriate timing, it becomes possible to significantly retard the ignition timing while stabilizing the rotation of the engine 10. Further, there is an advantage that the combustion speed becomes faster and the ignition timing can be largely retarded as compared with the case where PI injection is performed.

  Therefore, when the compression S / L mode is selected, the ignition timing is delayed in the retard mode, and the combustion reaction is advanced in the exhaust passage after the exhaust stroke (so-called afterburning state), thereby significantly increasing the exhaust temperature. It becomes possible to make it. Moreover, since the combustion speed in each cylinder 20a-20d falls by delaying ignition timing, the tendency of afterburning of fuel becomes strong, and the rising tendency of exhaust temperature is strengthened.

Additional retard mode, further increasing the retard amount in retarded mode (to increase the retard amount) is a mode for a predetermined time T _A from the beginning of the compression S / L mode is selected when the elapsed. However, in this additional retard mode, the ignition timing for the ignition plugs 17a to 17d of all the cylinders 20a to 20d is not changed, but the ignition for the ignition plugs 17b and 17c of the second cylinder 20b and the third cylinder 20c. The timing is controlled to be further delayed than in the retard mode.

Since the ignition order of the second cylinder 20b and the third cylinder 20c is not continuous, even if the ignition timing in the cylinders 20b and 20c is delayed, the rotational speed of the crankshaft 21 is unlikely to fluctuate, and the rotational stability of the engine 10 is improved. Secured. Further, as shown in FIG. 2, since these cylinders 20b and 20c are arranged inside the cylinder block 30, the temperature of the cylinder liner is hardly lowered and misfire due to retard is less likely to occur.
This additional retard mode is selected when the compression S / L mode is being implemented and it is determined that further increase in the exhaust gas temperature is necessary. In this embodiment, it is assumed that the catalyst temperature C is selected when it is equal to or lower than a predetermined temperature C ₀ (predetermined value).

[2-2. Control unit]
The engine control device 1 is provided with a fuel injection control unit 2, an ignition timing control unit 3, and a load control unit 4 as software or hardware for performing control in each of the above modes. A cooling water temperature sensor 5, a catalyst temperature sensor 6, an accelerator opening sensor 7, a crank angle sensor 8, and a vehicle speed sensor 9 are connected to the input side of the engine control device 1, and the cooling water temperature W, catalyst temperature C, accelerator opening P, Information on the rotation angle θ of the crankshaft 21 and the vehicle speed V is input. Further, the direct injection injectors 11a to 11d, the spark plugs 17a to 17d, the port injection injector 12 and the like of each cylinder 20a to 20d are connected to the output side of the engine control device 1.

  The fuel injection control unit 2 (fuel injection control means) controls the amount of fuel injected into the cylinder from the direct injection injectors 11a to 11d of the cylinders 20a to 20d and the timing of fuel injection. Here, selection conditions and selection cancellation conditions for the normal injection mode and the compression S / L mode are determined. These conditions are exemplified below. In the present embodiment, the normal injection mode is selected when any of the following conditions (A1) to (A5) is satisfied, and the compression S / L mode is satisfied with all of the following conditions (B1) to (B4). Selected when Further, based on the selected fuel injection mode, the fuel injection control unit 2 outputs a control signal for obtaining a desired engine output to each port injector 12.

Normal injection mode (A1) Elapsed time after engine start is less than predetermined time T _STA (A2) Elapsed time after engine start exceeds predetermined time T _END (however, T _STA <T _END )
(A3) The vehicle is not stopped (A4) The accelerator operation was performed (the accelerator was not fully closed)
(A5) cooling water temperature W is within a predetermined temperature W ₀ to exceed Compression S / L mode (B1) the elapsed time after engine start the predetermined time T _STA or more and the predetermined time T _END (B2) vehicle stops (B3) The accelerator is not operated (the accelerator is fully closed)
(B4) The cooling water temperature W is equal to or lower than the predetermined water temperature W _0.

  In addition, the fuel injection control unit 2 performs control for adjusting the fuel injection timing in the compression S / L mode in accordance with the ignition timing controlled by the ignition timing control unit 3 described in detail below. For example, when the retard mode is selected by the ignition timing control unit 3, the fuel injection timing is moved in the retarded direction as compared with the case where the normal ignition mode is selected, and further when the additional retard mode is selected. Increase the amount of retardation.

  The ignition timing control unit 3 (ignition control means) controls the timing of ignition at the ignition plugs 17a to 17d of the cylinders 20a to 20d. Here, the selection conditions and selection cancellation conditions for the normal ignition mode, the retard mode, and the additional retard mode are determined. These conditions are exemplified below. In the present embodiment, the retard mode is selected when both of the following conditions (D1) and (D2) are satisfied, and the additional retard mode is selected when all of the conditions (E1) to (E4) are satisfied. Further, based on the selected ignition mode, the ignition timing control unit 3 outputs a control signal to each of the spark plugs 17a to 17d.

-Normal ignition mode (C1) The fuel injection mode is the normal injection mode-Retard mode (D1) The fuel injection mode is the compression S / L mode (D2) The additional retard mode is not selected-Additional retard mode (E1 ) fuel injection mode is the compression S / L mode (E2) the elapsed time of the compression S / L mode is not less than the predetermined time T _a (E3) the cooling water temperature W is less than a predetermined water temperature W ₀ (E4) catalyst temperature C is below a predetermined temperature C ₀

  When the engine output decreases due to the ignition timing retard, the intake air amount into the cylinder is increased and the target value of the fuel injection amount controlled by the fuel injection control unit 2 is corrected in the increasing direction. The In this case, the exhaust gas flow rate increases compared to the case where the ignition timing is not retarded, and the catalyst temperature is more likely to rise.

  The load control unit 4 (load control means) performs control (load increase control) for increasing the load of the engine 10. Here, control for operating an air conditioner or an alternator (not shown) is performed. When the load of the engine 10 increases, the engine speed does not easily increase, and the target value of the fuel injection amount controlled by the fuel injection control unit 2 is corrected in the increasing direction. Along with this, the amount of intake air into the cylinder is also increased, so that the exhaust gas flow rate increases, and the tendency of the exhaust gas temperature to rise is strengthened.

The execution conditions of load increase control are illustrated below. In the present embodiment, the load of the engine 10 is added when all of the following conditions (F1) to (F4) are satisfied.
(F1) the fuel injection mode is the compression S / L mode (F2) the elapsed time of the compression S / L mode is not less than the predetermined time T _A (F3) the cooling water temperature W is the second predetermined water temperature W ₁ below ( However, W ₁ <W ₀ )
(F4) The catalyst temperature C is equal to or lower than the predetermined temperature C ₁ (where C ₁ <C ₀ ).

[3. flowchart]
Flowcharts relating to various controls that are performed when the engine 10 is started in a vehicle equipped with the engine control apparatus 1 are illustrated in FIGS. FIG. 3 is a flowchart of control related to selection of the fuel injection mode, FIG. 4 relates to selection of the ignition mode, and FIG. 5 relates to load increase control. These flows are repeatedly performed inside the engine control device 1 when the ignition switch of the vehicle equipped with the engine 10 is turned on.

[3-1. Fuel injection mode]
The flow in FIG. 3 corresponds to the control content performed by the fuel injection control unit 2.
In step A10, it is determined whether the elapsed time from the start of the engine 10 is _{equal to} or longer than the predetermined time T _STA and less than the predetermined time T _END . The start start time of the engine 10 that is a determination criterion for T _END is determined based on the amount of change in the rotation angle θ of the crankshaft 21, the engine speed Ne, and the like. When the condition of this step is satisfied, the process proceeds to step A20, and when not satisfied, the process proceeds to step A50 and the normal injection mode is selected. Even when the engine 10 is in the cranking state where the engine 10 has not yet been started, it is determined that the condition of step A10 is not satisfied, and the routine proceeds to step A50, where the normal injection mode is selected.

In step A20, it is determined whether or not the vehicle is stopped. For example, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 9 is a very small predetermined vehicle speed V ₀ or less (V ₀ = 0 may be used). Here, when V ≦ V ₀ , the process proceeds to step A30, and when V> V ₀ , the process proceeds to step A50.
In step A30, it is determined whether or not the accelerator opening P is fully closed (P = 0). If the accelerator operation is performed here, the process proceeds to step A50, and the normal injection mode is selected. On the other hand, if there is no accelerator operation, the process proceeds to step A40.

In step A40, the cooling water temperature W is equal to or less than a predetermined water temperature W ₀ is determined. When W ≦ W ₀ , the process proceeds to step A60, and the compression S / L mode is selected. On the other hand, when a W> W ₀ proceeds to step A50, the normal injection mode is selected. Here, the predetermined water temperature W ₀ is used as an index for determining whether the engine 10 is cold or warm.

[3-2. Ignition mode]
The flow in FIG. 4 corresponds to the control content performed by the ignition timing control unit 3.
In step B10, it is determined whether or not the fuel injection mode is the compression S / L mode. At this time, if the compression S / L mode is selected, the process proceeds to step B20. If the compression S / L mode is not selected (when the normal injection mode is selected), the process proceeds to step B60 and the normal ignition mode is selected. When the process proceeds to step B20, the selection condition for the compression S / L mode has already been established, so the cooling water temperature W is equal to or lower than the predetermined water temperature W ₀ .

In step B20, the elapsed time from the beginning of the compression S / L mode is equal to or more than a predetermined time T _A is determined. When the condition of this step is not satisfied, the process proceeds to step B50 and the retard mode is selected. On the other hand, when the condition of this step is satisfied, the process proceeds to Step B30.
In step B30, the catalyst temperature C is equal to or less than a predetermined temperature C ₀ is determined. Here, if C ≦ C ₀ , the process proceeds to step B40, and the additional retard mode is selected. On the other hand, if C> C ₀ , the process proceeds to step B50 and the retard mode is selected. The predetermined temperature C ₀ that is the determination threshold value of the catalyst temperature C is an index for determining whether or not the exhaust gas temperature needs to be further raised.

[3-3. Load increase control]
The flow in FIG. 5 corresponds to the control content executed by the load control unit 4.
In step C10, it is determined whether or not the fuel injection mode is the compression S / L mode. At this time, if the compressed S / L mode is selected, the process proceeds to step C20. If not the compressed S / L mode, the process proceeds to step C60.
In step C20, the elapsed time from the beginning of the compression S / L mode is equal to or more than a predetermined time T _A is determined. When the condition of this step is not satisfied, the process proceeds to Step C60, and when the condition of this step is satisfied, the process proceeds to Step C30.

At step C30, whether or not the cooling water temperature W is the second predetermined water temperature W ₁ or less is determined. If W ≦ W ₁ , the process proceeds to step C40, and if W> W ₁ , the process proceeds to step C60. Is the second predetermined water temperature W ₁ , which is the determination threshold value of the cooling water temperature W in this step, lower than the predetermined water temperature W ₀ included in the selection condition of the compression S / L mode, and is the engine 10 cold? It becomes an index for judging whether it is extremely cold.

In step C40, the catalyst temperature C is equal to or a predetermined temperature C ₁ or less is determined. Here, if C ≦ C ₁ , the process proceeds to step C50, and control for adding a load of the engine 10 is performed. On the other hand, when a C> C ₁ proceeds to step C60, the flow without load is added is completed. The predetermined temperature C ₁ that is the determination threshold value of the catalyst temperature C is also lower than the predetermined temperature C ₀ included in the selection conditions for the additional retard mode, and it is determined whether or not the exhaust temperature needs to be raised more quickly. It becomes an index to judge.

[4. Action]
FIG. 6 and FIG. 7 show the selected state of the mode and the temporal variation of various parameters related to the engine 10 when the control is performed according to the above-described flowchart when the engine 10 is started in the vehicle equipped with the engine 10. 6 corresponds to the cold start of the engine 10, and FIG. 7 corresponds to the cold start.

[4-1. During cold start]
In the example shown in FIG. 6, the catalyst temperature C before the start of the engine 10 is higher than the predetermined temperature C ₁ . When the ignition switch of the vehicle is turned on at time t ₀ , cranking of the engine 10 by the starter is started.
Thereafter, as shown in FIG. 6 (f), at time t ₁ the engine speed Ne becomes equal to or larger than a predetermined rotational speed, it is determined that the engine 10 is started. The time t ₁ corresponds to a measurement start time of the elapsed time according to the selection criteria of the compression S / L mode. The fuel injection mode selected immediately after the engine 10 is started is the normal injection mode, and the control pulse signal output from the fuel injection control unit 2 to the direct injection injector 11 causes PI injection or DI injection in the intake stroke. It will be a thing.

At time t ₂ from time t ₁ the predetermined time T _STA has elapsed, both the compression S / L mode in the fuel injection control unit 2 is selected, the retard mode is selected by the ignition timing control unit 3, each of the cylinders 20a~ The ignition timing at the 20d spark plugs 17a to 17d is controlled in the retarding direction. For example, FIG. 6 (d), the (e), the ignition timing of all of the spark plug 17a~17d is set to a predetermined value R _1. Also, FIG. 6 (b), the as shown in (c), the fuel injection timing of all of the direct injector 11a~11d is changed to a predetermined timing F ₁ in the compression stroke period. As a result, the exhaust gas temperature increases, the exhaust gas flow rate increases, the catalyst temperature C increases as shown in FIG. 6A, and the catalyst is activated early.

When the time t ₂ becomes the time t ₃ when the predetermined time T _A has passed, add the retard mode is selected by the ignition timing control unit 3. As a result, as shown in FIG. 6 (d), the ignition timing at the ignition plugs 17b, 17c of the second cylinder 20b and the third cylinder 20c is controlled to be more retarded than in the retard mode, and the ignition timing is reduced. It is set to a predetermined value R _2. Further, with the change of the ignition mode, the fuel injection control unit 2 changes the fuel injection timing in the retard direction. For example, as shown in FIG. 6 (b), the time t ₃ after the second cylinder 20b, the direct injector 11b of the third cylinder 20c, the fuel injection timing and 11c are adjusted so that further delays.

  By these controls, the rising tendency of the exhaust temperature is strengthened, and as shown in FIG. 6A, the rising gradient of the catalyst temperature C is increased, and further activation of the catalyst is promoted. When the additional retard mode is not performed, the catalyst temperature C rises slowly as shown by the broken line in FIG.

When the catalyst temperature C becomes equal to or higher than the predetermined temperature C _{0 at} time t ₄ , the additional retard mode is terminated, and the ignition timing control unit 3 selects the retard mode again. Therefore, as shown in FIG. 6D, the ignition timings of the spark plugs 17b and 17c of the second cylinder 20b and the third cylinder 20c are the same as the ignition timings of the spark plugs 17a and 17d of the first cylinder 20a and the fourth cylinder 20d. is re-set to the same predetermined value R _1. Accordingly, as shown in FIG. 6 (b), the second cylinder 20b, the direct injector 11b of the third cylinder 20c, the timing of fuel injection 11c is returned to the predetermined timing F _1.

Thereafter, from time t ₁ the predetermined time T _END is at time t ₅ and the compression S / L mode is terminated elapsed, the normal injection mode by the fuel injection control unit 2 is selected. At the same time, the retard mode is terminated, the normal ignition mode is selected by the ignition timing control unit 3, and the normal control of the engine 10 is performed.

[4-2. At extremely cold start]
In the example shown in FIG. 7, the catalyst temperature C before the start of the engine 10 is lower than the predetermined temperature C ₁ . In this case, until the time t ₃ shows a similar behavior as FIG. 6, the load increase control time t ₃ is performed, as shown in FIG. 7 (g), the engine load increases. As a result, as shown in FIG. 7A, the rising tendency of the exhaust temperature is further strengthened, and the rising gradient of the catalyst temperature C is further increased. Therefore, the time taken for the catalyst temperature C to reach the predetermined temperature C ₀ is further shortened.

When the catalyst temperature C becomes equal to or higher than the predetermined temperature C _{0 at} time t ₆ , the additional retard mode is terminated, the retard mode is selected by the ignition timing control unit 3, and the load increase control is also terminated. Incidentally, when the catalyst temperature C at the start of the engine 10 are the same, the length of time that the additional retard mode is executed (the period from time t ₃ in FIG. 7 to time t _6), the increase in the load control thereby considerably shortening the length of time when not carried (the period from time t ₃ in FIG. 6 to time t _4).

[5. effect]
(1) In the engine control apparatus 1 described above, in the engine 10 that performs in-cylinder injection in the compression stroke, the ignition timing is not simply retarded, and the second cylinder 20b and the third cylinder 20c whose ignition order is not continuous are used. The spark plugs 17a to 17d are controlled such that the ignition timing for is delayed from the ignition timing for the first cylinder 20a and the fourth cylinder 20d. With such a control configuration, the exhaust flow rate can be increased while ensuring the rotational stability of the engine 10, and the temperature rise performance of the exhaust and the catalyst device 22 can be improved. Thereby, the catalyst temperature C of the catalyst device 22 can be efficiently raised, and early activation of the catalyst and further improvement of the activity can be promoted.

  (2) Further, in the engine control apparatus 1 described above, the cylinders to be subjected to the additional retard in the additional retard mode are the second cylinder 20b and the third cylinder 20c, that is, the cylinders arranged inside the cylinder block 30. Only the control for increasing the retard amount (delaying the ignition timing) is performed. With such a control configuration, the temperature of the cylinder liner can be easily maintained, and misfire can be made difficult. Further, since the additional retard mode is performed immediately after the engine 10 is started, the startability of the engine 10 can be improved by improving the ignition performance and the heat retention of the cylinder liner.

  (3) In addition, in the engine control apparatus 1 described above, the ignition timing for all four cylinders is retarded instead of retarding the ignition timing of only the second cylinder 20b and the third cylinder 20c in the additional retard mode. I am letting. Thereby, the temperature of the exhaust gas discharged from all the cylinders 20a to 20d can be improved, and the temperature raising performance of the exhaust gas and the catalyst device 22 can be improved. Further, by retarding the ignition timings of the first cylinder 20a and the fourth cylinder 20d together, variation in the interval period between the ignition timings of the cylinders 20 can be reduced, and the rotational stability of the engine 10 is improved. be able to.

(4) Further, in the engine control apparatus 1 described above, the compression S / L mode and the additional retard mode are selected when the cooling water temperature W is equal to or lower than the predetermined water temperature W ₀ . In this way, by selecting the fuel injection mode and the ignition mode with reference to the water temperature of the engine coolant, it is possible to accurately grasp the state of the cold start of the engine 10 that should increase the temperature raising performance of the exhaust and the catalyst device 22. be able to.
Further, when the cooling water temperature W is sufficiently high, the catalyst temperature C is considered to reach the activation temperature early without selecting the compression S / L mode and the additional retard mode. In the engine control apparatus 1 described above, in such a case, the normal injection mode and the normal ignition mode are selected, so that the fuel consumption can be improved without impairing the exhaust performance.

  (5) Further, in the engine control apparatus 1 described above, when the engine 10 is in the extremely cold start state, control is performed to increase the engine load by driving the air conditioner or the alternator. Thereby, the exhaust gas flow rate can be easily increased, and the temperature rise performance of the exhaust gas and the catalyst device 22 can be further improved. Further, the time required for the catalyst temperature C to reach a desired temperature can be shortened, and the exhaust performance can be improved.

(6) In the engine control apparatus 1 described above, the second predetermined water temperature W ₁ that is the threshold value of the cooling water temperature W for performing the load increase control is higher than the predetermined water temperature W ₀ for selecting the additional retard mode. The temperature is set low. In other words, when the temperature range to be raised is relatively small, the additional retard mode with high temperature rise response is used, and when the temperature range is relatively large, load increase control with low temperature rise response is used. It is added. In this way, by performing the additional retard mode preferentially over the load increase control in accordance with the required temperature raising capacity, the exhaust temperature and the catalyst temperature C can be quickly raised, and the temperature that cannot be covered only by the additional retard. It is possible to improve the temperature rise performance of the exhaust and the catalyst device 22 by burdening the increase in the load increase control.

(7) In the engine control apparatus 1 described above, the catalyst temperature C is referred to as the additional retard mode selection condition. Specifically, the additional retard mode is selected when the catalyst temperature C is equal to or lower than the predetermined temperature C _0. Is done. With such a control configuration, it is possible to reliably raise the temperature of the exhaust system in an operating state where the temperature of the exhaust system needs to be increased. Further, when the catalyst temperature C exceeds the predetermined temperature C ₀ , the additional retard mode is terminated and the normal retard mode is selected, so that waste of fuel associated with ignition retard can be suppressed, and fuel efficiency is improved. Can be made.

  (8) Further, in the engine control apparatus 1 described above, the additional retard mode is selected under the compression S / L mode. That is, the retard amount in the additional retard mode is added to the retard amount in the compressed S / L mode. Thereby, for example, compared with the case where the additional retard mode is selected in the normal injection mode in which fuel is injected during the intake stroke, the change range of the ignition timing (total retard amount) can be increased (that is, the ignition timing). The exhaust gas and the temperature raising performance of the catalyst device 22 can be improved while ensuring the rotational stability of the engine.

  (9) Further, regarding the compressed S / L mode, the engine control apparatus 1 described above sets the DI injection timing when the additional retard mode is started, as shown in FIGS. 6 (b) and 7 (b). Further delay control is performed. In this way, by adjusting not only the ignition timing but also the timing of fuel injection, the retard amount in the additional retard mode can be further increased, and the exhaust and catalyst are secured while ensuring the rotational stability of the engine. The temperature rise performance of the device 22 can be improved.

(10) In addition, in the control of the additional retard mode in the in-line four-cylinder engine 10, it is preferable to set the second cylinder 20b and the third cylinder 20c as targets of the additional retard. That is, these cylinders not only satisfy the condition that the firing order is not continuous, but also satisfy the condition that they are arranged inside the cylinder block 30.
In the engine control apparatus 1 described above, since the ignition timing at the spark plugs 17b and 17c of the second cylinder 20b and the third cylinder 20c is an object of additional retard, both the rotational stability and the ignitability of the engine 10 are achieved. The temperature rise performance of the exhaust and catalyst device 22 can be improved.

[6. Modified example]
In the above-described embodiment, the engine control apparatus 1 having various modes such as the normal injection mode, the compression S / L mode, the normal ignition mode, the retard mode, and the additional retard mode is illustrated as a control mode when starting the engine 10. However, these control modes are not essential elements of the engine control apparatus 1 described above.
Further, the conditions (A1) to (F4) in the above-described embodiment are merely examples in the embodiment, and other conditions can be provided in addition to or in place of these, and are selected as necessary. It is also possible to do. By providing a condition that at least the above-described additional retard mode is selected at the time of performing the direct injection compression stroke injection, it is possible to realize control that exhibits the same effect as the above-described embodiment.

For example, in the above-described embodiment, the information on the cooling water temperature W is used to determine whether or not the engine 10 is in the cold start state. However, instead of the cooling water temperature W, the outside air temperature, the catalyst temperature C, The exhaust temperature in the exhaust passage 18, the exhaust temperature of the exhaust manifold 28, or the like may be used, or other parameters corresponding to these may be used. Alternatively, only the elapsed time from the start of the engine 10 may be used as a parameter.
In this case, it is possible to always determine that the engine 10 is in the cold start state when the elapsed time since the start is not sufficient regardless of the cooling water temperature W. As examples of 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, etc. may be used. It is done.

  In the above-described embodiment, the compression S / L mode selection condition and the additional retard mode selection condition are different from each other. However, as a simpler control method, the selection condition of each mode is the same. It is also possible. For example, a control configuration in which the compression S / L mode and the additional retard mode are always selected simultaneously when the engine 10 is started may be employed.

Further, in FIG. 6 of the above embodiments (d), although the ignition timing at the time of additional retard mode is shown that is fixed to a predetermined value R _2, when adding the retard mode retard amount (ignition timing The magnitude of the difference between the predetermined values R ₁ and R ₂ may be changed according to the cooling water temperature W, the catalyst temperature C, the outside air temperature, and the like. For example, the additional retard amount may be increased as the cooling water temperature W is lower, and the temperature rise effect of the exhaust or the catalyst device 22 may be enhanced.
The same applies to the load increase control, and the size of the load to be added may be changed according to the cooling water temperature W, the catalyst temperature C, the outside air temperature, or the like. For example, it is conceivable to increase the magnitude of the load to be added as the cooling water temperature W is lower. By such control, the temperature rise performance of the exhaust and the catalyst device 22 can be improved.

In the above-described embodiment, the details of control in the in-line four-cylinder engine 10 have been described in detail. However, the combustion type and the number of cylinders of the engine 10 are not limited thereto. As long as the engine is a multi-cylinder engine that performs at least in-cylinder injection, the above-described control can be performed for any gasoline engine or diesel engine.
It should be noted that the cylinders subject to the additional retard in the additional retard mode only need to have at least an ignition order that is not continuous, and therefore, when only one cylinder is retarded, any cylinder may be set as the target cylinder. For example, only the second cylinder 20b may be the target cylinder for the additional retard, or only the fourth cylinder 20d may be the target cylinder.

  When a plurality of cylinders 20 are the target cylinders, the first cylinder 20a and the fourth cylinder 20d may be the target cylinders for additional retarding instead of the second cylinder 20b and the third cylinder 20c. Since it is sufficient that at least the ignition order is not continuous, it is possible to appropriately select from combinations of cylinders whose ignition order is not continuous.

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 Fuel-injection control part (fuel-injection control means)
3 Ignition timing control unit (ignition control means)
4 Load control unit (load control means)
5 Cooling water temperature sensor (water temperature detection means)
6 Catalyst temperature sensor (catalyst temperature detection means)
10 Engine (Internal combustion engine)
11 Direct injection injector 17 Spark plug 20 cylinder

Claims (5)

A control device for a multi-cylinder internal combustion engine that performs in-cylinder injection,
Fuel injection control means for performing fuel injection into each cylinder of the internal combustion engine in a compression stroke;
The ignition timing of all cylinders is retarded during fuel injection by the fuel injection control means, and the ignition timing of some cylinders whose ignition sequence is not continued after a predetermined period from the start of the fuel injection is set to be higher than the ignition timing of other cylinders. A control device for an internal combustion engine, comprising ignition control means for retarding. Water temperature detection means for detecting the cooling water temperature of the internal combustion engine,
The fuel injection control means performs fuel injection into each cylinder of the internal combustion engine in a compression stroke when the cooling water temperature detected by the water temperature detection means is equal to or lower than a predetermined water temperature. The control device for an internal combustion engine according to claim 1. Comprising catalyst temperature detecting means for detecting the temperature of the catalyst device provided in the exhaust system of the internal combustion engine,
The ignition control means retards the ignition timing of some of the cylinders from the ignition timing of the other cylinders when the catalyst temperature is equal to or lower than a predetermined value after a lapse of a predetermined time from the ignition timing retard of all the cylinders. The control apparatus for an internal combustion engine according to claim 1 , wherein the control apparatus is an internal combustion engine. Load control means for controlling the load size of the internal combustion engine based on the cooling water temperature of the internal combustion engine;
Said load control means, when the cooling water temperature from retarding the ignition timing of all the cylinders is detected after a predetermined time has elapsed in the second predetermined water temperature less lower than the predetermined water temperature, and wherein the increasing the load The control device for an internal combustion engine according to any one of claims 1 to 3 . The internal combustion engine has a plurality of cylinders arranged in a row,
5. The internal combustion engine according to claim 1, wherein the ignition control unit retards an ignition timing of at least one of the plurality of cylinders other than the end portion. Control device.

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