JP2006258007A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To warm up an exhaust emission control catalyst, by taking into consideration a wall surface sticking correction of an intake port, without increasing the total fuel quantity, when starting an engine having an injector for cylinder injection and an injector for intake passage injection. <P>SOLUTION: An engine ECU executes a program including a step (S100) of detecting starting of the engine, a step (S120) of detecting the engine cooling water temperature THW when it is necessary to quickly warm up the catalyst (YES in S110), a step (S150) of calculating a cold increment correction value Q(P) of the injector for the intake passage injection by estimating a wall surface sticking quantity of the intake port (S140) when the THW is lower than a predetermined threshold value (YES in S130), a step (S160) of changing the DI ratio (r) so as to satisfy the cold increment correction value Q(P), and a step (S170) of executing quick catalyst warming-up processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides first fuel injection means (in-cylinder injector) for injecting fuel into the cylinder and second fuel injection means (intake passage injection) for injecting fuel into the intake passage or intake port. In particular, the present invention relates to a control device for an internal combustion engine when a catalyst for purifying exhaust gas is rapidly warmed up.

  An intake passage injector for injecting fuel into the engine intake passage and an in-cylinder injector for injecting fuel into the engine combustion chamber, and based on the engine speed and the engine load Internal combustion engines that determine the fuel injection ratio between an injector for injection and an injector for intake passage injection are known.

  In such an internal combustion engine, a control device for a direct injection spark ignition type internal combustion engine that activates a catalyst for purifying exhaust gas from the start of startup at an early stage is disclosed in Japanese Patent Laid-Open No. 11-324765 (Patent Document 1). Yes. This control device for a direct-injection spark-ignition internal combustion engine includes a fuel injection valve that directly injects fuel into the combustion chamber of the engine, a fuel supply means that forms a homogeneous air-fuel mixture throughout the combustion chamber, and an air-fuel mixture in the combustion chamber. The fuel injection amount during the compression stroke of the fuel injection valve so that the air-fuel ratio of the air-fuel mixture layer that is unevenly distributed around the ignition plug at the time of ignition is substantially stoichiometric when the ignition is performed under a predetermined engine operating condition And a direct-injection spark-ignition internal combustion engine that performs stratified combustion by controlling the fuel injection timing and the ignition timing of the spark plug. This control device is formed in the entire combustion chamber when a condition for determining the temperature of the exhaust purification catalyst disposed in the exhaust passage of the engine is determined and a condition for increasing the temperature of the exhaust purification catalyst. The fuel injection amount of the fuel supply means is controlled so that the air-fuel ratio of the air-fuel mixture is leaner than the stoichiometric and can be propagated through the flame, and the air-fuel ratio of the air-fuel mixture that is unevenly distributed around the spark plug at the time of ignition is Control means for performing the second stratified combustion by controlling the fuel injection amount during the compression stroke of the fuel injection valve, the fuel injection timing, and the ignition timing of the spark plug so as to be rich.

According to the control device of this direct injection spark ignition type internal combustion engine, the air-fuel ratio of the air-fuel mixture layer around the spark plug is made richer than the stoichiometric air-fuel ratio, so main combustion (ignition by spark ignition and subsequent combustion by flame propagation) Incomplete combustion products (CO) are generated during the combustion, and the CO remains in the combustion chamber even after the main combustion. Further, since a leaner air-fuel mixture is formed around the rich air-fuel mixture layer, oxygen remains in this region even after main combustion. This residual CO and residual oxygen are mixed and recombusted by the in-cylinder gas flow after the main combustion, and the exhaust temperature rises. Since incomplete combustion products (CO) are generated during the combustion process of the main combustion, they are already in a high temperature state at the end of the main combustion, and even if the combustion chamber temperature is low Can be burned well. In other words, the generated CO can be almost recombusted in the combustion chamber and in the exhaust passage upstream of the catalyst. In addition, compared with the homogeneous combustion where the amount of CO generated in the main combustion itself is small, the inflow amount of CO to the catalyst may increase, but the CO conversion start temperature of the catalyst is lower than the HC conversion start temperature. The impact on exhaust emissions is relatively small. In addition, since the air-fuel ratio of the lean air-fuel mixture is set to an air-fuel ratio that allows flame propagation, unburned HC does not occur at the boundary between the rich air-fuel mixture and the lean air-fuel mixture. In addition, since the flame propagates well to every corner of the combustion chamber, the low temperature region (quenching area) in the combustion chamber can be made a small region that is not different from that during homogeneous combustion. Furthermore, since the excess oxygen in the region where the lean air-fuel mixture burns remains after the main combustion, the temperature of the remaining oxygen at the end of the main combustion is also relatively high, and the CO reburns more. Proceed quickly.
JP 11-324765 A

  The following configuration is described in the above-described fourth embodiment of the patent document. As a fuel supply means for forming a homogeneous air-fuel mixture in the entire combustion chamber, the entire combustion chamber is driven by an exhaust stroke or an exhaust stroke or a fuel injection in an intake stroke by a fuel injection valve (fuel injection valve for intake port injection) provided in an intake passage. A fuel injection valve that injects fuel into the cylinder by using a fuel injection valve that forms a leaner lean mixture than stoichiometric and injects fuel into the cylinder. Also, a relatively rich (high fuel concentration) air-fuel mixture is formed in layers and burned. In the stratified stoichiometric combustion for activating the catalyst, specifically, a total fuel amount (substantially stoichiometric (theoretical air-fuel ratio)) that can be almost completely burned with the intake air amount per combustion cycle is achieved. For example, about 50% to about 90% of the fuel weight is injected into the intake passage (in the exhaust stroke or the exhaust stroke or the intake stroke) by the fuel injection valve for intake port injection. As a result, a fuel mixture that forms a relatively lean (lean) homogeneous air-fuel mixture in the entire combustion chamber during the intake stroke and injects the remaining fuel weight of approximately 50% to approximately 10% into the cylinder. It is described that fuel is injected and supplied into the combustion chamber by a valve during the compression stroke, and an air-fuel mixture that is relatively richer (higher fuel concentration) than the stoichiometric gas is formed around the spark plug and burned.That is, at the time of catalyst warm-up, the fuel sharing ratio between the in-cylinder fuel injection valve and the intake passage fuel injection valve is at least larger in the intake passage fuel injection valve.

  However, an exhaust gas in an internal combustion engine provided with such a fuel injection valve (in-cylinder injector) that injects fuel into the cylinder and a fuel injection valve (intake-path injector) that injects fuel into the intake passage. In order to realize early warm-up of the catalyst, such a sharing ratio is not optimal. That is, with respect to the ignition timing, which is the most important factor for warming up the catalyst, a sufficient retardation cannot be realized with such a sharing ratio.

  Further, during cold, in the region where fuel injection is shared by the in-cylinder injector and the intake manifold injector, the degree of temperature rise in the cylinder and the degree of temperature rise in the intake port Since they are different, the degree of adhesion of the injected fuel to the wall surface and the degree of adhesion to the piston upper surface are different. Therefore, the sharing ratio must be determined in consideration of the amount of wall surface adhesion. Otherwise, the target fuel sharing ratio and the fuel sharing ratio in the combustion chamber do not coincide with each other, so that the combustion mode as described above cannot be obtained, and early warm-up of the catalyst cannot be realized. In such a case, the amount of wall surface adhesion at the cooler intake port will be increased, but if the amount of fuel from the intake manifold injector is simply increased, the total fuel amount will increase and the fuel consumption will deteriorate, Exhaust components may deteriorate.

  In addition, during cold weather, the amount of wall surface adhesion at the intake port is corrected to increase, but the fuel whose increase has been corrected needs to be decreased when it is no longer affected by temperature. Depending on the degree of reduction (attenuation rate) in this case, the target fuel sharing ratio as described above does not match the fuel sharing ratio in the combustion chamber, and the combustion mode as described above cannot be obtained. The catalyst cannot be warmed up early.

  The present invention has been made to solve the above-mentioned problems, and has as its object the first fuel injection means for injecting fuel into the cylinder and the first for injecting fuel into the intake passage. Control of an internal combustion engine that performs good warm-up of the exhaust purification catalyst at the start of the internal combustion engine having the fuel injection means of 2 and does not increase the total fuel amount in consideration of wall surface adhesion during cold Is to provide a device.

  According to a first aspect of the present invention, there is provided a control device for an internal combustion engine comprising: a first fuel injection means for injecting fuel into a cylinder; a second fuel injection means for injecting fuel into an intake passage; and an ignition device. The internal combustion engine provided is controlled. The exhaust system of the internal combustion engine is provided with an exhaust purification catalyst that is activated above a predetermined temperature. The control device is configured to share fuel between the first fuel injection unit and the second fuel injection unit based on a detection unit for detecting a catalyst warm-up request and a condition required for the internal combustion engine. Control means for controlling the fuel injection means to inject, ignition control means for controlling the ignition device, and detection means for detecting the temperature of the internal combustion engine. In the case where fuel injection is shared between the first fuel injection means and the second fuel injection means, the control means considers the temperature of the internal combustion engine when a warm-up request is detected, Means for controlling the first fuel injection means and the second fuel injection means so that the share of the first fuel injection means is equal to or greater than the share of the second fuel injection means . The ignition control means includes means for controlling the ignition device so as to retard the ignition timing when a warm-up request is detected.

  According to the first invention, the share of the first fuel injection means (for example, in-cylinder injector) is equal to or greater than the share of the second fuel injection means (for example, intake manifold injector). In this way (for example, 65% is shared by the in-cylinder injector), fuel is injected in the compression stroke using the in-cylinder injector. In this way, a homogeneous mixture (a mixture with a lean air / fuel ratio as a whole) by the intake manifold injector and a stratified mixture (a mixture with a rich air / fuel ratio around the spark plug) by the in-cylinder injector Can be formed in the combustion chamber. At this time, in particular, since the ratio of the in-cylinder injector is equal or higher, the air-fuel ratio of the air-fuel mixture around the spark plug can be made richer. Further, since the mixture around the stratified mixture is a homogeneous mixture, the propagation of the flame can be made good. That is, in the fuel spray state, even at the boundary between the air-fuel mixture layer rich in the air-fuel ratio around the spark plug and the homogeneous air-fuel mixture layer, the region where the air-fuel ratio becomes lean due to fuel diffusion does not partially occur, Since there is no such region, the flame is easy to propagate and unburned fuel (HC) is hardly generated. In such a state, the ignition timing can be greatly retarded, and the exhaust temperature can be easily raised. This is because the air-fuel ratio of the air-fuel mixture around the spark plug is richer than the stoichiometric air-fuel ratio, so incomplete combustion products during main combustion (ignition by spark ignition by the spark plug and subsequent combustion by flame propagation) (CO) is generated, and this CO remains in the combustion chamber even after the main combustion. Oxygen remains after the main combustion in the homogeneous mixed layer where the air-fuel ratio is around the rich mixed gas layer and the air-fuel ratio is lean. The residual CO and residual oxygen are mixed by the in-cylinder gas flow after the main combustion and recombusted, so that the exhaust temperature is considered to rise. By increasing the exhaust temperature, the catalyst can be warmed up quickly and the catalyst can be activated early, while suppressing the discharge of HC into the atmosphere from the start to the activation of the catalyst. Such a warm-up operation is performed at a cold start when the temperature of the internal combustion engine is low. At this time, the in-cylinder injector directly injects fuel into the high-temperature cylinder. The conversion is good. On the other hand, since the intake manifold injector injects fuel into a low-temperature intake port, atomization is not good. That is, the fuel is attached to the wall surface of the intake port and the state of atomization is poor. In such a case, the fuel is normally injected into the intake port by adding the wall surface adhering amount to the fuel injection amount from the intake manifold injector (increase correction). For this reason, the total fuel amount (the sum of the fuel amount of the in-cylinder injector and the fuel amount of the injector for the intake passage injection in which the wall surface adhesion amount is added) increases, resulting in deterioration of fuel consumption and exhaust components. appear. In the first aspect of the invention, the lower the temperature of the internal combustion engine, the lower the share ratio of the in-cylinder injector and the higher the share ratio of the intake passage injector, thereby increasing the fuel injection amount from the intake passage injector. By doing so, fuel is injected in consideration of the amount of adhesion on the wall. Since only the sharing ratio is changed and the total fuel amount does not change, it is possible to avoid deterioration of fuel consumption and exhaust components. As a result, the exhaust purification catalyst is rapidly activated at the time of starting the internal combustion engine including the first fuel injection means for injecting fuel into the cylinder and the second fuel injection means for injecting fuel into the intake passage. It is possible to provide a control device for an internal combustion engine that performs warm-up well and does not increase the total amount of fuel in consideration of wall surface adhesion during cold.

  The control apparatus for an internal combustion engine according to a second aspect of the invention includes, in addition to the configuration of the first aspect of the invention, a wall surface deposition amount of fuel injected into the intake passage by the second fuel injection means based on the temperature of the internal combustion engine. It further includes a calculation means for calculating. The control means includes means for controlling the first fuel injection means and the second fuel injection means in consideration of the amount of wall surface adhesion.

  According to the second invention, the wall surface adhesion amount is calculated by the calculating means based on the temperature of the internal combustion engine. Considering this amount of wall adhesion, lower the share ratio of the in-cylinder injectors and increase the share ratio of the intake manifold injectors, and increase the total fuel amount without increasing the total fuel amount. The amount of fuel injected from the injector for passage injection can be increased.

  In the control apparatus for an internal combustion engine according to the third invention, in addition to the configuration of the second invention, the control means increases the share of the second fuel injection means in consideration of the wall surface adhesion amount, Means for changing the ratio of sharing between the first fuel injection means and the second fuel injection means.

  According to the third invention, in consideration of the wall surface adhesion amount, the share ratio of the in-cylinder injector is lowered to increase the share ratio of the intake manifold injector, and the total fuel amount is not increased and the wall surface adhesion amount is increased. The amount of fuel injected from the intake manifold injector can be increased by a corresponding amount.

  In the control apparatus for an internal combustion engine according to the fourth aspect of the invention, in addition to the configuration of the second aspect of the invention, the control means increases the fuel injection amount by the second fuel injection means so as to correspond to the wall surface adhesion amount. Means for increasing the share of the second fuel injection means and changing the share of the first fuel injection means and the second fuel injection means.

  According to the fourth aspect of the invention, the share ratio of the intake manifold injector is increased so as to increase by the amount of wall surface adhesion (relatively the share ratio of the in-cylinder injector decreases). As a result, the amount of fuel injected from the intake manifold injector can be increased by an amount corresponding to the wall surface adhesion amount without increasing the total fuel amount.

  In the control apparatus for an internal combustion engine according to the fifth aspect of the invention, in addition to the configuration of any one of the second to fourth aspects, the control means may perform the first fuel injection even when the amount of wall surface adhesion is taken into account. The first fuel injection means and the second fuel injection means, so that the sum of the fuel injection amount from the means and the fuel injection amount from the second fuel injection means is smaller than the case where the wall surface adhesion amount is not considered. Means for controlling.

  According to the fifth invention, in consideration of the wall surface adhesion amount, the sharing ratio of the in-cylinder injector is lowered to increase the sharing ratio of the intake manifold injector. As a result, the amount of fuel injected from the intake manifold injector can be increased by the amount corresponding to the wall surface adhesion amount, and the total fuel amount does not increase.

  A control device for an internal combustion engine according to a sixth aspect of the invention is configured to attenuate the fuel injection amount of the second fuel injection means corrected for increase based on the temperature of the internal combustion engine in addition to the configuration of the fourth aspect of the invention. Further comprising weight loss means.

  According to the sixth invention, when the temperature of the internal combustion engine rises, it is necessary to restore the increase correction amount of the fuel amount injected from the intake manifold injector. At this time, the decay rate for the increase correction (for example, the degree of reduction per unit time) is determined according to the temperature of the internal combustion engine, and while maintaining a ratio suitable for rapidly warming up the catalyst, The amount of increase correction can be restored.

  In the control apparatus for an internal combustion engine according to the seventh aspect of the invention, in addition to the configuration of the sixth aspect of the invention, the reducing means attenuates the fuel injection quantity that has been increased and corrected more rapidly as the temperature of the internal combustion engine is higher. Including means.

  According to the seventh aspect of the invention, the higher the temperature of the internal combustion engine (the higher the temperature increase of the internal combustion engine may be), the smaller the need to consider the wall surface adhering amount of the intake port. For this reason, as the temperature of the internal combustion engine is higher, the fuel injection amount corrected for the increase can be sharply attenuated and returned to the original state.

  In the control apparatus for an internal combustion engine according to the eighth aspect of the invention, in addition to the configuration of the sixth aspect of the invention, the reducing means attenuates the fuel injection quantity corrected for increase gradually as the temperature of the internal combustion engine decreases. Including means.

  According to the eighth aspect of the invention, the lower the temperature of the internal combustion engine (the lower the temperature increase of the internal combustion engine may be), the longer the time during which it is necessary to take into account the wall surface adhering amount of the intake port. For this reason, as the temperature of the internal combustion engine is lower, the fuel injection amount corrected for increase is gradually attenuated to return to the original state, and a desired combustion mode can be realized to realize rapid warm-up of the catalyst.

  In the control device for an internal combustion engine according to the ninth aspect of the invention, in addition to the configuration of any of the sixth to eighth aspects, the reducing means supplies the fuel injection quantity corrected for the increase to the fuel of the second fuel injection means. Means for reducing the injection quantity.

  According to the ninth aspect of the present invention, it is possible to reduce the amount only from the intake manifold injector that has been subjected to the increase correction, and to return to the original state.

  In the control apparatus for an internal combustion engine according to the tenth aspect of the invention, in addition to the configuration of any of the sixth to eighth aspects, the reducing means supplies the fuel injection quantity corrected for increase to the fuel of the first fuel injection means. Means for reducing the injection amount and the fuel injection amount of the second fuel injection means are included.

  According to the tenth aspect of the present invention, it is possible to return to the original state by reducing the amount in consideration of the sharing ratio from both the intake manifold injector and the in-cylinder injector that have been subjected to the increase correction.

  In the control device for an internal combustion engine according to the eleventh aspect of the invention, in addition to the configuration of any of the sixth to eighth aspects of the invention, the reducing means uses the fuel injection amount that has been corrected for the increase as the first fuel before the increase correction. Means for reducing the weight are included so as to maintain the proportion of the share between the injection means and the second fuel injection means.

  According to the eleventh aspect of the present invention, both the intake manifold injector and the in-cylinder injector that have been subjected to the increase correction can be reduced to the original state while maintaining the sharing ratio before the increase correction.

  In the control apparatus for an internal combustion engine according to the twelfth aspect of the invention, in addition to the configuration of any of the sixth to eighth aspects of the invention, the reducing means uses the fuel injection amount that has been corrected for increase as the first fuel after the increase correction. Means for reducing the weight are included so as to maintain the proportion of the share between the injection means and the second fuel injection means.

  According to the twelfth aspect of the present invention, it is possible to return to the original state by reducing the amount while maintaining the sharing ratio after the increase correction, from both the intake manifold injector and the in-cylinder injector that have been subjected to the increase correction.

  In the control device for an internal combustion engine according to the thirteenth invention, in addition to the configuration of any one of the first to twelfth inventions, the first fuel injection means is an in-cylinder injector, and the second fuel The injection means is an intake passage injector.

  According to a thirteenth aspect of the present invention, there is provided an internal combustion engine in which an in-cylinder injector that is a first fuel injection means and an intake passage injection injector that is a second fuel injection means are separately provided to share the injected fuel. It is possible to provide a control device for an internal combustion engine that does not increase the total amount of fuel in consideration of wall surface adhesion during cold when the exhaust purification catalyst is rapidly warmed up when the engine is started.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 shows a schematic configuration diagram of an engine system controlled by an engine ECU (Electronic Control Unit) which is a control device for an internal combustion engine according to the present embodiment. Although FIG. 1 shows an in-line four-cylinder gasoline engine as the engine, the present invention is not limited to such an engine.

  As shown in FIG. 1, the engine 10 includes four cylinders 112, and each cylinder 112 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to an air cleaner 50 via an intake duct 40, an air flow meter 42 is disposed in the intake duct 40, and a throttle valve 70 driven by an electric motor 60 is disposed. The opening degree of throttle valve 70 is controlled based on the output signal of engine ECU 300 independently of accelerator pedal 100. On the other hand, each cylinder 112 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  For each cylinder 112, an in-cylinder injector 110 for injecting fuel into the cylinder, and an intake passage injection injector 120 for injecting fuel into the intake port or / and the intake passage. And are provided respectively. These injectors 110 and 120 are controlled based on the output signal of engine ECU 300, respectively. The in-cylinder injectors 110 are connected to a common fuel distribution pipe 130, and this fuel distribution pipe 130 is connected to the fuel distribution pipe 130 through a check valve 140, and is driven by an engine. A high-pressure fuel pump 150 is connected. In the present embodiment, an internal combustion engine in which two injectors are separately provided will be described, but the present invention is not limited to such an internal combustion engine. For example, it may be an internal combustion engine having one injector that has both an in-cylinder injection function and an intake passage injection function.

  As shown in FIG. 1, the discharge side of the high-pressure fuel pump 150 is connected to the suction side of the high-pressure fuel pump 150 via an electromagnetic spill valve 152. When the amount of fuel supplied from the pump 150 into the fuel distribution pipe 130 is increased and the electromagnetic spill valve 152 is fully opened, the fuel supply from the high pressure fuel pump 150 to the fuel distribution pipe 130 is stopped. ing. Electromagnetic spill valve 152 is controlled based on the output signal of engine ECU 300.

  On the other hand, each intake passage injector 120 is connected to a common low-pressure fuel distribution pipe 160, and the fuel distribution pipe 160 and the high-pressure fuel pump 150 are connected to a common fuel pressure regulator 170 through an electric motor drive type. The low-pressure fuel pump 180 is connected. Further, the low pressure fuel pump 180 is connected to the fuel tank 200 via a fuel filter 190. The fuel pressure regulator 170 returns a part of the fuel discharged from the low-pressure fuel pump 180 to the fuel tank 200 when the fuel pressure of the fuel discharged from the low-pressure fuel pump 180 becomes higher than a predetermined set fuel pressure. Accordingly, the fuel pressure supplied to the intake manifold injector 120 and the fuel pressure supplied to the high-pressure fuel pump 150 are prevented from becoming higher than the set fuel pressure.

  The engine ECU 300 is composed of a digital computer, and is connected to each other via a bidirectional bus 310, a ROM (Read Only Memory) 320, a RAM (Random Access Memory) 330, a CPU (Central Processing Unit) 340, and an input port 350. And an output port 360.

  The air flow meter 42 generates an output voltage proportional to the amount of intake air, and the output voltage of the air flow meter 42 is input to the input port 350 via the A / D converter 370. A water temperature sensor 380 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine 10, and the output voltage of the water temperature sensor 380 is input to the input port 350 via the A / D converter 390.

  A fuel pressure sensor 400 that generates an output voltage proportional to the fuel pressure in the fuel distribution pipe 130 is attached to the fuel distribution pipe 130, and the output voltage of the fuel pressure sensor 400 is input via the A / D converter 410. Input to port 350. The exhaust manifold 80 upstream of the three-way catalytic converter 90 is provided with an air-fuel ratio sensor 420 that generates an output voltage proportional to the oxygen concentration in the exhaust gas. The output voltage of the air-fuel ratio sensor 420 is converted into an A / D converter. It is input to the input port 350 via 430.

The air-fuel ratio sensor 420 in the engine system according to the present embodiment is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 420 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned in the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  The accelerator pedal 100 is connected to an accelerator opening sensor 440 that generates an output voltage proportional to the depression amount of the accelerator pedal 100, and the output voltage of the accelerator opening sensor 440 is input to the input port 350 via the A / D converter 450. Is input. The input port 350 is connected to a rotational speed sensor 460 that generates an output pulse representing the engine rotational speed. In the ROM 320 of the engine ECU 300, the value of the fuel injection amount and the engine cooling that are set according to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 440 and the engine speed sensor 460 described above are stored. Correction values based on the water temperature and the like are previously mapped and stored.

  The three-way catalytic converter 90 purifies the exhaust by oxidizing CO and HC in the exhaust and reducing NOx in the vicinity of the theoretical air-fuel ratio (A / F (air weight / fuel weight) = 14.7). It is a three-way catalyst that can The catalyst (platinum, rhodium, palladium, etc.) in the three-way catalytic converter 90 is not activated unless its temperature reaches a certain level (high temperature), and the purification function does not act.

  In the control apparatus according to the present embodiment, after starting engine 10 including in-cylinder injector 110 and intake passage injector 120, three-way catalytic converter 90 is heated up early to activate the catalyst. In order to make exhaust gas purification work as soon as possible immediately after the engine 10 is started, such an early temperature increase process is restricted if the altitude of the vehicle on which the engine 10 is mounted is high. Whether or not the three-way catalytic converter 90 has been activated can be determined by detecting the concentration of a specific component (for example, oxygen) in the exhaust on the exhaust downstream side of the three-way catalytic converter 90. For example, it is determined whether or not an oxygen sensor provided on the downstream side of the three-way catalytic converter 90 is activated. Specifically, whether or not the three-way catalytic converter 90 is activated is determined based on the change in the detection signal of the downstream oxygen sensor. This is because the oxygen sensor provided on the downstream side of the three-way catalytic converter 90 is activated due to the rise (oxidation reaction) of the exhaust gas temperature on the outlet side of the activation of the three-way catalytic converter 90. It is determined that the catalytic converter 90 has been activated.

  Further, it is possible to estimate the temperature of the three-way catalytic converter 90 by detecting the temperature of the engine cooling water or the oil temperature of the engine oil, and to determine the activation of the three-way catalytic converter 90 based on the result. Furthermore, activation of the three-way catalytic converter 90 can also be determined by directly detecting the temperature (outlet temperature) of the three-way catalytic converter 90.

  When the temperature of the engine 10 (temperature determined from the value detected by the water temperature sensor 380 that detects the engine cooling water temperature) is low, the intake manifold is also low in temperature, and the fuel injected from the intake manifold injector 120 is low in temperature. Since it adheres to the wall surface of the intake port, the state of fuel atomization is not good. For this reason, normally, an increase correction process for increasing the amount of wall adhesion to the fuel injection amount from the intake manifold injector 120 is performed. When this increase correction processing is performed, the total fuel amount (the sum of the fuel injection amount from the in-cylinder injector 110 and the fuel injection amount from the intake manifold injector 120 with the increased wall surface adhesion amount) increases. As a result, fuel consumption and exhaust components deteriorate. The program executed in the engine ECU 300 that is the control device according to the present embodiment realizes early warm-up control without increasing the total fuel amount.

  This engine 10 injects fuel by in-cylinder injector 110 and intake passage injector 120. Injection ratio of in-cylinder injector 110 and intake manifold injector 120 stored in ROM 320 of engine ECU 300 (hereinafter also referred to as direct injection ratio, DI ratio, DI ratio r (or simply r)) A map representing the will be described. In such a map, for example, the engine rotation speed is plotted on the horizontal axis, the load factor is plotted on the vertical axis, and the share ratio of the in-cylinder injector 110 is shown as a percentage as the direct injection ratio (DI ratio r). .

  A direct injection ratio (DI ratio r) is set for each operation region determined by the engine speed and the load factor. “Direct injection 100%” means a region where fuel injection is performed only from the in-cylinder injector 110 (r = 1.0, r = 100%), and “direct injection 0-20%”. Means that the fuel injection from the in-cylinder injector 110 is a region (r = 0 to 0.2) that is 0 to 20% of the total injection amount. For example, “direct injection 40%” indicates that 40% of the total injection amount is injected from in-cylinder injector 110 and 60% of the total injection amount is injected from intake manifold injector 120. Details of such a map will be described later.

  With reference to FIG. 2, a control structure of a program executed by engine ECU 300 that is the control device according to the present embodiment will be described.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 300 determines whether engine 10 has been started or not. At this time, the determination is made based on an engine start request signal input from another ECU to engine ECU 300 or a result processed by engine ECU 300 itself. When engine 10 is started (YES in S100), the process proceeds to S110. Otherwise (NO in S100), this process ends.

  In S110, engine ECU 300 determines whether or not rapid catalyst warm-up is necessary. At this time, as described above, if the three-way catalytic converter 90 is not activated based on the change in the detection signal of the oxygen sensor provided on the downstream side of the three-way catalytic converter 90, the rapid catalyst warm-up is necessary. It is judged. Further, it may be determined whether or not rapid catalyst warm-up is necessary from the temperature of the engine cooling water or the oil temperature of the engine oil. If rapid catalyst warm-up is necessary (YES in S110), the process proceeds to S120. If not (NO in S110), the process proceeds to S190.

  In S120, engine ECU 300 detects cooling water temperature THW of engine 10. At this time, engine coolant temperature THW is detected based on a signal from water temperature sensor 380.

  In S130, engine ECU 300 determines whether or not coolant temperature THW is lower than threshold value THW (1). If it is determined that cooling water temperature THW is lower than threshold value THW (1) (YES in S130), the process proceeds to S140. If not (NO in S130), the process proceeds to S170. If it is determined that the coolant temperature THW is equal to or lower than the threshold value THW (1), the process may be moved to S140.

  In S140, engine ECU 300 estimates the amount of fuel adhering to the port wall surface. At this time, the engine ECU may estimate the fuel adhesion amount to the port wall surface from a cooling water temperature THW of the engine 10, an outside air temperature (intake air temperature), and the like using a predetermined map.

  In S150, engine ECU 300 calculates a cold increase correction value Q (P) of intake manifold injector 120. This cold increase correction value Q (P) is a fuel amount for increasing the fuel adhesion amount on the port wall surface.

  In S160, engine ECU 300 causes the fuel amount obtained by adding the cold increase correction value Q (P) to the basic fuel amount of intake passage injector 120 to be the amount of fuel injected from intake passage injector 120. Then, the DI ratio r is changed. At this time, the total fuel amount (the sum of the fuel injection amount from the in-cylinder injector 110 and the fuel injection amount from the intake manifold injector 120 with the increased wall surface adhesion amount) does not increase. Details of this will be described later.

  In S170, engine ECU 300 executes a rapid catalyst warm-up process. At this time, for example, as shown in FIG. 3, the ignition timing, the injection timing of in-cylinder injector 110, the fuel injection amount, the supply air amount, and the DI ratio r are controlled by engine ECU 300. The value of the DI ratio in FIG. 3 is an example, and may be 50% or more (the sharing ratio of the in-cylinder injector 110 is equal to or more than the sharing ratio of the intake manifold injector 120). Further, as an example of the fuel amount reduction, the air-fuel ratio in the exhaust may be in a lean state of about 15.5. By reducing the amount in this way, unburned HC is also reduced. Immediately after the engine 10 is started, an increase correction is made (an increase correction for responding to the torque required at the start of the engine 10 or an increase correction for responding to adhesion of the wall surface). Since the starting torque is not required or the fuel adhering to the wall surface is saturated, the amount of fuel is reduced. As described above, even if the fuel injection amount in the compression stroke from the in-cylinder injector 110 is reduced, only the fuel amount necessary for ignition exists in the vicinity of the spark plug, and the lean limit is increased so that no misfire occurs. Then, afterburning fuel that contributes to catalyst warm-up (the amount supplied from the intake manifold injector 120) is supplied in a required amount (by increasing correction). Since there is a burnt fuel after this, catalyst warm-up can be achieved.

  In S180, engine ECU 300 determines whether or not to end the rapid catalyst warm-up. At this time, as described above, if the three-way catalytic converter 90 is activated based on the change in the detection value of the oxygen sensor provided on the downstream side of the three-way catalytic converter 90, the rapid catalyst warm-up ends. To be judged. Further, it may be determined whether or not to end the rapid catalyst warm-up from the temperature of the engine cooling water or the oil temperature of the engine oil. Further, it may be determined whether or not to end the rapid catalyst warm-up based on whether or not the temperature of the engine cooling water has risen by a predetermined value or more from the start. Further, based on the integrated value of the intake air amount, it is determined whether or not the rapid catalyst warm-up is to be ended by determining whether or not the engine 10 has been operated for a predetermined time or more. Good. If it is determined that rapid catalyst warm-up is to be ended (YES in S180), the process proceeds to S190. If not (NO in S180), the process returns to S170 and the rapid catalyst warm-up is continued.

  In S190, engine ECU 300 executes normal operation processing for engine 10. At this time, the ignition timing, the injection timing of the in-cylinder injector 110, the fuel injection amount, the supply air amount, and the DI ratio r temporarily set for rapid catalyst warm-up are set for normal operation by the engine ECU 300. Returned.

  An operation of engine 10 controlled by engine ECU 300 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described. In the following description, the operation when the engine 10 is started when the rapid catalyst warm-up is required and the fuel injection amount from the intake manifold injector 120 is corrected to the cold increase will be described. .

  If the engine 10 is started (YES in S100) and the three-way catalytic converter 90 is not activated based on the change in the detection signal of the oxygen sensor provided downstream of the three-way catalytic converter 90, the rapid catalyst warm-up is performed. It is determined that the machine is necessary (YES in S110). When the temperature of the engine 10 (cooling water temperature THW) is detected (S120) and the cooling water temperature THW is lower than the threshold value THW (1), the fuel injected from the intake manifold injector 120 adheres to the wall surface of the port. The amount of wall surface adhesion to be performed is estimated (S140). A cold increase correction value Q (P) of the intake passage injector 120 is calculated from the estimated wall surface adhesion amount (S150), and in-cylinder injection is performed so as to increase the cold increase correction value Q (P). The fuel sharing ratio between the injector 110 and the intake passage injector 120 is changed.

  The state at this time will be described with reference to FIG. For simplification of explanation, the basic condition of catalyst warm-up calculated based on FIG. 3 (when the correction of port wall surface adhesion correction in the cold state is not considered) is that the total fuel amount is 1.00 and the DI ratio r Is 65%. This state is shown in FIG. Since the total fuel amount is 1.00, the fuel injection amount Q (D) ALL from the in-cylinder injector 110 is 0.65, and the fuel injection amount Q (P) ALL from the intake passage injector 120 is 0. .35. It is assumed that the wall surface adhesion amount estimated at this time is 0.20 and the cold increase correction value Q (P) is also 0.20 (actually, it was estimated in consideration of other factors). A cold increase correction value Q (P) is calculated from the wall surface adhesion amount). That is, as shown in FIG. 4B, 0.20 of the fuel of 0.35 that is the fuel injection amount Q (P) ALL injected from the intake manifold injector 120 adheres to the wall surface and takes into account combustion. Not. Therefore, among the total fuel amount of 1.00, the fuel contributing to combustion is 0.65 injected from the in-cylinder injector 110 and the intake passage injector 120 (out of 0.35). It is 0.80 which is the sum of 0.15.

  In such a case, as an example of the prior art, as shown in FIG. 4D, only 0.20 which is a cold increase correction value Q (P) is added to only the fuel injection amount from the intake manifold injector 120. It was. The total fuel amount at this time is 1.20. As another conventional example, as shown in FIG. 4E, a cold increase correction value Q is added to the fuel injection amount from the in-cylinder injector and the fuel injection amount from the intake manifold injector 120, respectively. 0.20 which is (P) was added. The total fuel amount at this time is 1.40. As another example of the prior art, as shown in FIG. 4 (F), 0.20 which is a cold increase correction value Q (P) is added only to the fuel injection amount from the intake manifold injector 120. However, the in-cylinder injector 110 is increased so as not to change the DI ratio r (= 65%) in FIG. The total fuel amount at this time is 1.57.

  In contrast, DI ratio r is changed as shown in FIG. 4C by engine ECU 300 which is the control device according to the present embodiment (S160). That is, the DI ratio r is decreased from 65% to 56% so that the fuel injection amount from the intake passage injector 120 can be injected with the cold increase correction value Q (P) from the intake passage injector 120. Yes. The total fuel amount at this time is 0.80.

  The rapid catalyst warm-up process is performed at the DI ratio r (= 56%) thus changed (S170). At this time, conditions other than the DI ratio r are values as shown in FIG.

  In the engine controlled in this way, the share of the in-cylinder injector 110 is set to about 65% that is equal to or greater than the share of the intake passage injector 120 (in this case) 56%), fuel is injected from the in-cylinder injector 110 into the cylinder in the compression stroke. From the intake passage injector 120, fuel is injected into the intake pipe in the intake stroke. At this time, the air-fuel ratio is lean as a whole by the intake manifold injector 120 and the air-fuel mixture in the stratified state is rich in the air-fuel ratio around the spark plug by the in-cylinder injector 110 in the combustion chamber. It is formed. Even if the ignition timing at the spark plug is greatly retarded (for example, ATDC 15 °), the ratio of the in-cylinder injector 110 is equal or higher, so the air-fuel ratio of the air-fuel mixture around the spark plug is richer. Furthermore, since the air-fuel mixture around the spark plug is a homogeneous air-fuel mixture formed by the intake manifold injector 120, flame propagation can be improved. Thus, the flame is easy to propagate and unburned fuel (HC) is not easily generated. By significantly retarding the ignition timing, the exhaust temperature rises.

  By taking such a rapid catalyst warm-up process into consideration, the intake port is cooled and the fuel injected from the intake passage injector 120 adheres to the wall surface of the port. The amount increase correction can be realized by changing the DI ratio r without increasing the total fuel amount.

  As described above, in the vehicle equipped with the engine ECU according to the present embodiment, when the engine is started and the exhaust purification catalyst needs to be quickly warmed up, the fuel injection sharing by the in-cylinder injector is performed. The rate is set to be equal to or higher than the fuel injection sharing rate of the intake manifold injector. In this way, the air-fuel ratio is lean as a whole by the intake manifold injector and the mixture in the homogeneous state and the stratified mixture in the air-fuel ratio around the spark plug by the in-cylinder injector are rich in the combustion chamber. Can be formed. At this time, the air-fuel ratio of the air-fuel mixture around the spark plug can be made richer. Since the air-fuel mixture around the spark plug is homogeneous (weakly stratified), the flame easily propagates and unburned fuel (HC) is not easily generated. In such a state, the exhaust gas temperature can be raised by greatly retarding the ignition timing, and the exhaust gas purification catalyst can be warmed up more rapidly than in the prior art.

  In such a case, when the engine temperature is low and the rapid warm-up operation is performed, the fuel injected from the intake manifold injector to the low-temperature intake port adheres to the wall surface of the intake port and the atomized state is bad. In such a case, normally, the wall surface adhering amount is added to the fuel injection amount from the intake passage injector and the fuel is injected into the intake port to obtain the total fuel amount (the fuel amount of the in-cylinder injector and the wall surface). The sum of the fuel amount of the intake manifold injector to which the adhesion amount is added) increases. At this time, by reducing the share ratio of the in-cylinder injector and increasing the share ratio of the intake manifold injector, and increasing the fuel injection amount from the intake manifold injector, the amount of adhesion on the wall surface is taken into consideration. Inject fuel. This is because only the sharing ratio is changed and the total fuel amount does not change, so that it is possible to avoid deterioration of fuel consumption and exhaust components. As a result, the exhaust purification catalyst is quickly warmed up at the time of cold start of the engine equipped with the in-cylinder injector and the intake passage injector, and the wall surface adhesion in the cold state is taken into consideration. The amount of fuel can be prevented from increasing.

<Decrease of cold increase correction value Q (P)>
The increased cold increase correction value Q (P) is returned to the original value because the temperature of the intake port increases as the temperature of the engine 10 rises (with the passage of time from the start of the engine 10). It is necessary to set the increase correction value Q (P) to 0 over time). Hereinafter, the return method at this time will be described. In the following, the amount by which the cold increase correction value Q (P) per hour is reduced is referred to as “attenuation rate”.

  The higher the temperature of the engine 10 (the higher the temperature rise of the engine 10), the less it becomes necessary to consider the wall surface adhesion amount of the intake port. For this reason, the damping rate is increased as the temperature of the engine 10 is higher and as the temperature of the engine 10 is higher. This is shown in FIG. As shown in FIG. 5, as the attenuation rate increases with time, the original state is restored earlier. In the example shown in FIG. 5, the amount is decreased by 0.20 which is the cold increase correction value Q (P) on the intake passage injector 120 side. As a result, the fuel injection amount from the in-cylinder injector 110 is 0.45, the fuel injection amount from the intake manifold injector 120 is 0.15, and the DI ratio r converges to 75%. The example shown in FIG. 5 is characterized in that the cold increase correction value Q (P) is decreased only from the intake manifold injector 120.

  Further, as shown in FIG. 6, the cold increase correction value Q (P) is maintained while maintaining the DI ratio r (= 56%) when the increase is made by the cold increase correction value Q (P). It is also possible to reduce the amount by 0.20 minutes. As a result, the fuel injection amount from the in-cylinder injector 110 is 0.336, the fuel injection amount from the intake passage injector 120 is 0.264, and the DI ratio r remains 56%. That is, in the example shown in FIG. 6, the sharing ratio between the in-cylinder injector 110 and the intake manifold injector 120 is the sharing ratio after considering the cold increase correction value Q (P) (r = 56%). ) Is maintained to reduce the weight.

  Further, as shown in FIG. 7, the cold increase correction value Q (P), which is the cold increase correction value Q (P), is returned to the DI ratio r (= 65%) before being increased by the cold increase correction value Q (P). You can also try to lose 20 minutes. As a result, the fuel injection amount from the in-cylinder injector 110 becomes 0.39, the fuel injection amount from the intake passage injector 120 becomes 0.21, and the DI ratio r is returned to 65%. That is, in the example shown in FIG. 7, the sharing ratio between the in-cylinder injector 110 and the intake manifold injector 120 is set to a sharing ratio before considering the cold increase correction value Q (P). The feature is that the weight is reduced.

  In the example shown in FIGS. 5 to 7, the total fuel amount is 0.60, but the total fuel amount is not limited to 0.60. Further, the DI ratio is not limited to the examples shown in FIGS. 5 to 7, and is controlled based on, for example, an injection division map of the engine 10 described later.

  As described above, as shown in FIGS. 5 to 7, the higher the temperature of the engine 10 and the higher the rate of change in the temperature of the engine 10, the lower the need for considering the wall surface of the intake port. It is enlarged so that it can be quickly restored.

<Engine suitable for application of this control apparatus (part 1)>
Hereinafter, an engine (part 1) suitable for application of the control device according to the present embodiment will be described.

  Referring to FIGS. 8 and 9, the injection ratio of in-cylinder injector 110 and intake manifold injector 120 (hereinafter referred to as DI ratio r or simply r), which is information corresponding to the operating state of engine 10. ) Will be described. These maps are stored in the ROM 320 of the engine ECU 300. FIG. 8 is a warm map of the engine 10, and FIG. 9 is a cold map of the engine 10.

  As shown in FIG. 8 and FIG. 9, these maps are shown in percentages where the engine 10 rotational speed is on the horizontal axis, the load factor is on the vertical axis, and the share ratio of the in-cylinder injector 110 is the DI ratio r. It is shown.

  As shown in FIGS. 8 and 9, the DI ratio r is set for each operation region determined by the rotational speed and load factor of the engine 10. “DI ratio r = 100%” means a region where fuel injection is performed only from in-cylinder injector 110, and “DI ratio r = 0%” means from intake manifold injector 120. This means that only the region where fuel injection is performed. “DI ratio r ≠ 0%”, “DI ratio r ≠ 100%” and “0% <DI ratio r <100%” indicate that in-cylinder injector 110 and intake passage injector 120 perform fuel injection. It means that the area is shared. In general, the in-cylinder injector 110 contributes to an increase in output performance, and the intake manifold injector 120 contributes to the uniformity of the air-fuel mixture. By using the two types of injectors having different characteristics depending on the engine speed and the load factor, the engine 10 is in a normal operation state (for example, when the catalyst is warmed up at idle time except for the normal operation state). In this case, only homogeneous combustion is performed.

  Further, as shown in FIGS. 8 and 9, the DI share ratio r of the in-cylinder injector 110 and the intake manifold injector 120 is defined by dividing it into a warm map and a cold map. did. If the temperature of the engine 10 is different, the temperature of the engine 10 is detected by detecting the temperature of the engine 10 using a map set so that the control areas of the in-cylinder injector 110 and the intake manifold injector 120 are different. If it is equal to or higher than a predetermined temperature threshold, the map at the time of warm in FIG. 8 is selected, and if not, the map at the time of cold shown in FIG. 9 is selected. Based on the selected maps, the in-cylinder injector 110 and / or the intake manifold injector 120 are controlled based on the rotation speed and load factor of the engine 10.

  The engine speed and load factor of engine 10 set in FIGS. 8 and 9 will be described. In FIG. 8, NE (1) is set to 2500 to 2700 rpm, KL (1) is set to 30 to 50%, and KL (2) is set to 60 to 90%. Further, NE (3) in FIG. 9 is set to 2900-3100 rpm. That is, NE (1) <NE (3). In addition, NE (2) in FIG. 8 and KL (3) and KL (4) in FIG. 9 are also set as appropriate.

  Comparing FIG. 8 and FIG. 9, NE (3) of the cold map shown in FIG. 9 is higher than NE (1) of the warm map shown in FIG. This indicates that as the temperature of the engine 10 is lower, the control range of the intake manifold injector 120 is expanded to a higher engine speed range. That is, since the engine 10 is in a cold state, deposits are unlikely to accumulate at the injection port of the in-cylinder injector 110 (even if fuel is not injected from the in-cylinder injector 110). For this reason, it sets so that the area | region which injects a fuel using the intake manifold injector 120 may be expanded, and a homogeneity can be improved.

  8 and 9, the engine speed of the engine 10 is "DI ratio r" in the region where NE (1) or higher in the map for warm and NE (3) or higher in map for cold. = 100% ". Further, the load factor is “DI ratio r = 100%” in the region of KL (2) or higher in the warm map and in the region of KL (4) or higher in the cold map. This indicates that only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. . That is, in the high speed region and the high load region, even if the fuel is injected only by the in-cylinder injector 110, the engine 10 has a high rotational speed and load, and the intake amount is large. It is because it is easy to homogenize. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the warm map shown in FIG. 8, only the in-cylinder injector 110 is used at a load factor KL (1) or less. This indicates that when the temperature of the engine 10 is high, only the in-cylinder injector 110 is used in a predetermined low load region. This is because when the engine 10 is warm, the engine 10 is in a warm state, and deposits are likely to accumulate at the injection port of the in-cylinder injector 110. However, since the injection port temperature can be lowered by injecting fuel using the in-cylinder injector 110, it is conceivable to avoid deposit accumulation, and the minimum fuel injection amount of the in-cylinder injector Therefore, it is conceivable that the in-cylinder injector 110 is not blocked, and for this purpose, the in-cylinder injector 110 is used.

  Comparing FIG. 8 and FIG. 9, there is an area of “DI ratio r = 0%” only in the cold map of FIG. This indicates that when the temperature of the engine 10 is low, only the intake manifold injector 120 is used in a predetermined low load region (KL (3) or less). This is because the engine 10 is cold and the load on the engine 10 is low and the intake air amount is low, so that the fuel is difficult to atomize. In such a region, it is difficult to perform good combustion with the fuel injection by the in-cylinder injector 110. In particular, a high output using the in-cylinder injector 110 is required in the region of low load and low rotation speed. Therefore, only the intake passage injector 120 is used without using the in-cylinder injector 110.

  In addition, in the case other than the normal operation, when the engine 10 is idling when the catalyst is warmed up (when the engine 10 is in a non-normal operation state), the in-cylinder injector 110 is controlled to perform stratified combustion. By causing stratified charge combustion only during such catalyst warm-up operation, catalyst warm-up is promoted and exhaust emission is improved.

<Engine suitable for application of this control device (part 2)>
Hereinafter, an engine (part 2) suitable for application of the control device according to the present embodiment will be described. In the following description of the engine (part 2), the same description as the engine (part 1) will not be repeated here.

  With reference to FIGS. 10 and 11, a map representing the injection ratio between in-cylinder injector 110 and intake passage injector 120, which is information corresponding to the operating state of engine 10, will be described. These maps are stored in the ROM 320 of the engine ECU 300. FIG. 10 is a warm map for the engine 10, and FIG. 11 is a cold map for the engine 10.

  10 and 11 differ from FIGS. 8 and 9 in the following points. The rotational speed of the engine 10 is “DI ratio r = 100%” in the region of NE (1) or more in the warm map and in the region of NE (3) or more in the cold map. In the region where the load factor is KL (2) or higher excluding the low rotational speed region in the warm map, and in the region where KL (4) is higher than the low rotational speed region in the cold map, “DI” Ratio r = 100% ”. This is because only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. Indicates. However, in the high load region of the low engine speed region, mixing of the air-fuel mixture formed by the fuel injected from the in-cylinder injector 110 is not good, and the air-fuel mixture in the combustion chamber is inhomogeneous and combustion is unstable. Tend to be. For this reason, the injection ratio of the in-cylinder injector is increased with the shift to the high rotation speed region where such a problem does not occur. In addition, the injection ratio of the in-cylinder injector 110 is decreased as the engine shifts to a high load region where such a problem occurs. These changes in the DI ratio r are indicated by cross arrows in FIGS. If it does in this way, the fluctuation | variation of the output torque of an engine resulting from combustion being unstable can be suppressed. It should be noted that these things can be achieved by reducing the injection ratio of the in-cylinder injector 110 as the engine shifts to the predetermined low rotational speed region, or by the in-cylinder injection as the vehicle shifts to the predetermined low load region. The fact that it is substantially equivalent to increasing the injection ratio of the injector 110 for operation will be described. Further, areas other than such areas (areas where the crossed arrows are described in FIGS. 10 and 11) and areas where fuel is injected only by the in-cylinder injector 110 (high rotation side, low load) On the other hand, it is easy to homogenize the air-fuel mixture with the in-cylinder injector 110 alone. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the engine 10 described with reference to FIGS. 8 to 11, the homogeneous combustion uses the fuel injection timing of the in-cylinder injector 110 as the intake stroke, and the stratified combustion uses the fuel of the in-cylinder injector 110. This can be realized by setting the injection timing to the compression stroke. That is, by setting the fuel injection timing of the in-cylinder injector 110 as the compression stroke, stratified combustion is realized in which the rich air-fuel mixture is unevenly distributed around the spark plug and the entire combustion chamber ignites a lean air-fuel mixture. Can do. Further, even when the fuel injection timing of the in-cylinder injector 110 is set to the intake stroke, if rich air-fuel mixture can be unevenly distributed around the spark plug, stratified combustion can be realized even with the intake stroke injection.

  Further, the stratified combustion here includes both stratified combustion and weakly stratified combustion described below. In the weak stratified combustion, the intake passage injector 120 is injected with fuel in the intake stroke to produce a lean and homogeneous mixture in the entire combustion chamber, and the in-cylinder injector 110 is injected with fuel in the compression stroke. A rich air-fuel mixture is generated around the spark plug to improve the combustion state. Such weak stratified combustion is preferable when the catalyst is warmed up. This is due to the following reason. In other words, when the catalyst is warmed up, it is necessary to significantly retard the ignition timing and maintain a good combustion state (idle state) in order to allow high-temperature combustion gas to reach the catalyst. Moreover, it is necessary to supply a certain amount of fuel. Even if this is done by stratified combustion, there is a problem that the amount of fuel is small, and even if this is done by homogeneous combustion, there is a problem that the retard amount is small compared to stratified combustion in order to maintain good combustion. is there. From this point of view, the above-described weak stratified combustion is preferably used when the catalyst is warmed up, but either stratified combustion or weak stratified combustion may be used.

  Further, in the engine described with reference to FIGS. 8 to 11, the fuel injection timing by the in-cylinder injector 110 is preferably performed in the compression stroke for the following reason. However, in the engine 10 described above, in most of the basic areas (intake only when the catalyst is warmed up, the intake manifold injector 120 is injected in the intake stroke, and the in-cylinder injector 110 is injected in the compression stroke. The timing of fuel injection by the in-cylinder injector 110 other than the weakly stratified combustion region is the intake stroke. However, for the following reasons, the fuel injection timing of the in-cylinder injector 110 may be temporarily set to the compression stroke injection for the purpose of stabilizing the combustion.

  By setting the fuel injection timing from the in-cylinder injector 110 during the compression step, the air-fuel mixture is cooled by fuel injection at a time when the in-cylinder temperature is higher. Since the cooling effect is enhanced, knock resistance can be improved. Furthermore, if the fuel injection timing from the in-cylinder injector 110 is in the compression step, the time from the fuel injection to the ignition timing is short, so that the airflow can be strengthened by spraying and the combustion speed can be increased. From these improvement in knocking property and increase in combustion speed, combustion fluctuation can be avoided and combustion stability can be improved.

  Furthermore, regardless of the temperature of the engine 10 (that is, whether the engine is warm or cold), the engine 10 is off-idle (when the idle switch is off and the accelerator pedal is depressed). May use the warm map shown in FIG. 8 or 10 (the in-cylinder injector 110 is used in the low load region regardless of the cold warm).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram of an engine system controlled by a control device according to an embodiment of the present invention. It is a flowchart which shows the control structure of the program performed by engine ECU which is a control apparatus which concerns on embodiment of this invention. It is a figure which shows the conditions of the rapid catalyst warm-up process in embodiment of this invention. It is a figure which shows the state for the wall surface adhesion increase amount performed with engine ECU which is a control apparatus which concerns on embodiment of this invention. It is FIG. (The 1) which shows the state of the reduction process for the wall surface adhesion increase executed by engine ECU which is a control apparatus which concerns on embodiment of this invention. It is FIG. (2) which shows the state of the reduction process for the wall surface adhesion increase executed by engine ECU which is a control apparatus which concerns on embodiment of this invention. It is FIG. (The 3) which shows the state of the reduction process for the wall surface adhesion increase executed by engine ECU which is a control apparatus which concerns on embodiment of this invention. FIG. 5 is a diagram (No. 1) showing a DI ratio map when the engine is suitable for application of the control device according to the embodiment of the present invention. It is FIG. (1) showing the DI ratio map at the time of cold of an engine suitable for the control apparatus which concerns on embodiment of this invention to be applied. FIG. 6 is a diagram (No. 2) showing a DI ratio map when the engine is suitable for application of the control device according to the embodiment of the present invention. FIG. 6 is a diagram (No. 2) showing a DI ratio map during cold engine suitable for application of the control device according to the embodiment of the present invention;

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 100 accelerator pedal, 110 in-cylinder injector , 112 cylinder, 120 Injector injector, 130 Fuel distribution pipe, 140 Check valve, 150 High pressure fuel pump, 152 Electromagnetic spill valve, 160 Fuel distribution pipe (low pressure side), 170 Fuel pressure regulator, 180 Low pressure fuel pump, 190 fuel filter, 200 fuel tank, 300 engine ECU, 310 bidirectional bus, 320 ROM, 330 RAM, 340 CPU, 350 input port, 360 output port, 370, 39 , 410,430,450 A / D converter, 380 a water temperature sensor, 400 a fuel pressure sensor, 420 an air-fuel ratio sensor, 440 an accelerator opening sensor, 460 rpm sensor.

Claims (13)

A control device for an internal combustion engine, comprising: a first fuel injection means for injecting fuel into a cylinder; a second fuel injection means for injecting fuel into an intake passage; and an ignition device. The exhaust system of the engine is provided with an exhaust purification catalyst that is activated above a predetermined temperature,
Detection means for detecting a warm-up request of the catalyst;
Control means for controlling the fuel injection means so as to inject fuel in a shared manner between the first fuel injection means and the second fuel injection means based on conditions required for the internal combustion engine; ,
Ignition control means for controlling the ignition device;
Detecting means for detecting the temperature of the internal combustion engine,
The control means considers the temperature of the internal combustion engine when the warm-up request is detected when fuel injection is shared by the first fuel injection means and the second fuel injection means. Then, the first fuel injection means and the second fuel injection means are set so that the share of the first fuel injection means is equal to or greater than the share of the second fuel injection means. Including means for controlling
The control device for an internal combustion engine, wherein the ignition control means includes means for controlling the ignition device so as to retard an ignition timing when the warm-up request is detected. The control device further includes a calculation unit for calculating a wall surface adhesion amount of the fuel injected into the intake passage by the second fuel injection unit based on the temperature of the internal combustion engine,
2. The control apparatus for an internal combustion engine according to claim 1, wherein the control means includes means for controlling the first fuel injection means and the second fuel injection means in consideration of the wall surface adhesion amount. .   The control means increases the share of the second fuel injection means in consideration of the wall surface adhesion amount, and changes the share of the first fuel injection means and the second fuel injection means. The control apparatus for an internal combustion engine according to claim 2, comprising means for   The control means increases the fuel injection amount by the second fuel injection means to increase the share of the second fuel injection means to correspond to the wall surface adhesion amount, and increases the share of the second fuel injection means. The control device for an internal combustion engine according to claim 2, further comprising means for changing a share ratio between the means and the second fuel injection means.   Even if the control unit takes into account the wall surface adhesion amount, the sum of the fuel injection amount from the first fuel injection unit and the fuel injection amount from the second fuel injection unit is equal to the wall surface adhesion amount. The internal combustion engine according to any one of claims 2 to 4, further comprising means for controlling the first fuel injection means and the second fuel injection means so as to be smaller than when the amount is not considered. Control device.   5. The control of the internal combustion engine according to claim 4, wherein the control device further includes a reduction means for attenuating the fuel injection amount of the second fuel injection means that has been corrected for increase based on the temperature of the internal combustion engine. apparatus.   The control device for an internal combustion engine according to claim 6, wherein the reduction means includes means for attenuating the fuel injection amount corrected for increase in a sharper manner as the temperature of the internal combustion engine is higher.   The control device for an internal combustion engine according to claim 6, wherein the reduction means includes a means for slowly attenuating the fuel injection amount that has been corrected for increase as the temperature of the internal combustion engine decreases.   The control device for an internal combustion engine according to any one of claims 6 to 8, wherein the reduction means includes means for reducing the fuel injection amount corrected for increase from the fuel injection amount of the second fuel injection means. .   The said reduction | decrease means includes a means for reducing the fuel injection quantity by which increase correction | amendment was carried out from the fuel injection quantity of a said 1st fuel injection means, and the fuel injection quantity of a said 2nd fuel injection means. The control apparatus for an internal combustion engine according to any one of claims 8 to 10.   The reduction means has means for reducing the fuel injection amount that has been corrected for increase so as to maintain the proportion of the share between the first fuel injection means and the second fuel injection means before the increase correction. A control device for an internal combustion engine according to any one of claims 6 to 8.   The reduction means has means for reducing the fuel injection amount that has been corrected for increase so as to maintain a ratio of the share of the first fuel injection means and the second fuel injection means after the increase correction. A control device for an internal combustion engine according to any one of claims 6 to 8. The first fuel injection means is an in-cylinder injector,
The control device for an internal combustion engine according to any one of claims 1 to 12, wherein the second fuel injection means is an intake passage injector.

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