JP2009216040A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the degree of vaporization of fuel contained in circulating oil in a control device 40 which supplies oil to portions of an internal combustion engine 1 to be lubricated, recovers the oil, and supplies the oil again to the portions to be lubricated. <P>SOLUTION: This control device 40 comprises control means S5-S8 each performing vaporization promoting treatment for promoting the vaporization of the fuel contained in the oil by increasing an oil lubrication amount as required during the warm operation of the internal combustion engine 1 and vaporization suppressing treatment for suppressing the vaporization of the fuel contained in the oil by reducing the oil lubrication amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device that supplies oil to a lubricated part of an internal combustion engine and performs an oil circulation process such that the oil is recovered and supplied to the lubricated part again.

  The internal combustion engine to which the control device according to the present invention is applied is, for example, a direct injection type internal combustion engine that directly injects fuel into a cylinder, or a port injection type that injects fuel into an intake port, for example. An internal combustion engine, or an internal combustion engine of a type provided with both in-cylinder direct injection and port injection can be used.

  For example, in an in-cylinder direct injection internal combustion engine in which fuel is directly injected into a cylinder, since the atomization of fuel in the cylinder is difficult to be accelerated particularly during cold operation, the injected fuel is In addition, there is a tendency that a large amount adheres to the inner peripheral surface of the cylinder.

  Normally, during cold operation, the fuel injection timing is set during the intake stroke (intake stroke injection), and the period from fuel injection to ignition is secured as long as possible to promote atomization of the injected fuel. .

  However, even if such an intake stroke injection is performed, it is difficult to completely eliminate the fuel adhesion, and some fuels are not used for combustion and remain in the cylinders even after combustion. May remain.

  Of such fuel adhering, especially the fuel adhering to the top surface of the piston is incompletely combusted and discharged from the cylinder. In extreme cases, for example, PM (Particulate Matter) and black smoke are generated. And exhaust properties such as increase in unburned components.

  On the other hand, the amount of the adhering fuel adhering to the inner peripheral surface of the cylinder is mixed with the piston lubrication and cooling oil adhering to the inner peripheral surface of the cylinder. So-called oil dilution occurs.

  The oil in the cylinder diluted with fuel in this way is scraped off along with the vertical movement of the piston and returned to the oil pan, and the oil in the oil pan is at least a lubricated part (piston in the cylinder of the internal combustion engine). Are supplied (jet injection). Such oil circulation is performed.

  By the way, if the oil dilution as described above frequently occurs, the ratio of the fuel mixed in the whole oil gradually increases, and may eventually lead to a large deviation in the injection amount correction amount and a decrease in the lubrication performance of the internal combustion engine. is there. Incidentally, in the situation where a so-called cold short trip is repeated, in which a cold operation is repeated for a short time, or in a situation where a continuous high-load operation is performed, the oil dilution is likely to proceed.

  Therefore, in order to cope with both deterioration of exhaust properties and oil dilution, it is conventionally monitored whether, for example, an operation in which the degree of dilution of oil with fuel increases during the period from the start to the stop of the internal combustion engine is performed. Then, it is considered to control the fuel injection timing so as to suppress the dilution when it is determined to increase (see, for example, Patent Document 1).

Incidentally, the fuel injection timing for suppressing the dilution is set to a timing at which the piston is positioned on the top dead center side to reduce the fuel collision (liner wet) to the cylinder inner peripheral surface.
Japanese Patent No. 3797278

  In the conventional example according to Patent Document 1 described above, when fuel injection is performed on the piston top dead center side in order to suppress the oil dilution, the liner wet can be reduced, but the fuel collision (piston wet) on the piston top surface is caused. Because of the increase, vaporization of the fuel adhering to the piston top surface becomes insufficient, and a lot of PM, black smoke and the like tend to be discharged.

  By the way, even if oil dilution occurs, the fuel mixed in the oil is gradually vaporized as the temperature (water temperature, oil temperature, etc.) of each part of the internal combustion engine rises. In the case of continuing the operation at a low temperature, it can be said that the oil dilution that occurs in the cold state is to some extent acceptable.

  In consideration of this, with regard to the fuel injection timing, the piston wet is reduced as much as possible and the increase in the liner wet is allowed so as to give priority to suppressing the deterioration of the exhaust property by allowing a certain amount of oil dilution. Setting in the direction is considered preferable in practice. However, in this case, it can be said that the oil dilution cannot be positively reduced because the oil dilution is naturally eliminated during the warm operation of the internal combustion engine.

  For this reason, the present inventor does not actively suppress the progress of oil dilution by controlling the fuel injection timing, but promotes the vaporization of the fuel mixed in the oil to increase the degree of oil dilution. It came to propose the technique of making it reduce.

  For reference, as shown in Japanese Patent Application Laid-Open No. 2004-308578, when the internal combustion engine is low in oil pressure, such as during low-speed operation or cold operation, the oil return to the oil pan is reduced. A technique has been disclosed in which oil is retained around the cylinder block by reducing the amount to quickly raise the oil temperature. This conventional example merely presents that it is described that the oil return amount can be adjusted to increase or decrease, and discloses the technical idea of linking the increase and decrease of the oil return amount and the increase or decrease of the oil dilution. There is no suggestion.

  In addition, in general, in an internal combustion engine, feedback control of the fuel injection amount that is obtained based on the tendency of deviation between the actual air-fuel ratio and the target air-fuel ratio, that is, air-fuel ratio feedback control is performed. When the correction amount is greater than or equal to the specified value, it is determined that the fuel injection system is malfunctioning, and an abnormality is reported. As a form of this abnormality notification, for example, a MIL (Malfunction Indicator Lamp) indicating that the fuel injection system is abnormal is turned on.

  However, the reduction amount correction amount of the fuel injection amount exceeds the specified value because, in addition to the case where an essential malfunction of the fuel injection system occurs, for example, even if the fuel injection system is normal, the temperature of the internal combustion engine As the fuel gas rises, vaporization of the fuel in the oil is promoted in the circulation process of the oil diluted with the fuel, and the fuel concentration in the blow-by gas introduced into the intake system becomes high. In some cases, the amount of correction on the reduction side may exceed the specified value. Even in the latter case, the conventional abnormality diagnosis determines that there is an abnormality and performs abnormality notification.

  As described above, in the conventional abnormality diagnosis of the fuel injection system, it cannot be said that a correct determination is made, and the reliability is low.

  In order to suppress such erroneous determination, Japanese Patent Application Laid-Open No. 2003-332047 and Japanese Patent Application Laid-Open No. 2007-127076 have been proposed.

  First, in Japanese Patent Laid-Open No. 2003-332047, the degree of oil dilution is estimated by examining the operation history of the internal combustion engine, and when the degree of oil dilution is large, it is determined that the fuel injection system is not abnormal. .

  On the other hand, in Japanese Patent Application Laid-Open No. 2007-127076, if the correction amount becomes excessively large in air-fuel ratio feedback control, the fuel injection valve is normal and the blow-by valve is normal unless the air-fuel ratio fluctuates by reducing the fuel pressure of the high-pressure fuel system. Although it is determined that the gas processing is the cause and the abnormality notification is retained, if the air-fuel ratio fluctuates, it is determined that the fuel injection valve is abnormal and the abnormality notification is performed.

  Although these conventional techniques can suppress erroneous determination, they do not remove factors that lead to erroneous determination. There is room for improvement here.

  The present invention provides a control device for supplying oil to a lubricated part of an internal combustion engine, and recovering this oil and supplying it to the lubricated part again. The purpose is to enable control.

  Further, the present invention provides a control device that performs oil circulation processing in which oil is supplied to a lubricated part of an internal combustion engine, and this oil is recovered and supplied to the lubricated part again. In addition to making the degree controllable, it is possible to avoid erroneous determination of the presence or absence of abnormality in the fuel injection system during operation (for example, warm idle operation) in which the fuel injection amount reduction correction amount by air-fuel ratio feedback control tends to be large. , That is the purpose.

The present invention is a control device that supplies oil to a lubricated part of an internal combustion engine and performs an oil circulation process such that the oil is recovered and supplied to the lubricated part again.
During the warm operation of the internal combustion engine, if necessary, a vaporization promotion process for increasing the amount of oil circulation to promote the vaporization of fuel in the oil, and a vaporization of fuel in oil by reducing the amount of oil circulation. It is characterized by including a management means for executing vaporization suppression processing to be suppressed.

  Examples of the lubricated portion of the internal combustion engine include a piston inner surface, a cylinder inner peripheral surface, a crank journal, and a valve mechanism.

  When the oil circulation amount of the internal combustion engine is increased or decreased during the warm operation as in this configuration, it becomes possible to promote or suppress the vaporization of the fuel in the oil. The degree of dilution can be adjusted. As a result, the residual fuel in the circulating oil can be reduced as much as possible, and the original lubricating performance of the circulating oil can be maintained.

  Incidentally, if the amount of oil circulation of the internal combustion engine is reduced during the warm operation, the amount of oil touching the lubricated part is reduced, so that the fuel vaporization in the circulating oil is reduced. On the other hand, when the amount of oil circulation in the internal combustion engine is increased, the amount of oil that comes into contact with the lubricated portion increases, so that fuel vaporization in the circulating oil increases.

  Moreover, if the oil dilution degree can be adjusted without controlling the fuel injection timing as described above, for example, with respect to the fuel injection timing, fuel adhesion to the piston top surface is suppressed, PM, black smoke generation, etc. Since it is possible to set with an emphasis on suppressing deterioration of properties, it can be said that it becomes relatively easy to achieve both adjustment of the degree of oil dilution and improvement of deterioration of exhaust properties as a result. .

  Furthermore, as the degree of oil dilution can be reduced, the fuel concentration in the blow-by gas to be introduced into the intake system can be reduced, so that it is possible to reduce the fuel injection amount reduction amount correction amount, which leads to abnormalities in the fuel injection system. Judgment can be avoided.

  The present invention also provides a control device for supplying oil to a lubricated part of an internal combustion engine and performing an oil circulation process for recovering this oil and supplying it to the lubricated part again. An air-fuel ratio control means for performing feedback correction of the fuel injection amount with respect to the basic fuel injection amount based on a deviation from the target air-fuel ratio, a determination means for checking whether or not the operating state in which the fuel injection amount reduction-side correction amount tends to be large, When the determination means determines that the fuel injection amount reduction-side correction amount is likely to increase, the oil circulation amount is increased or decreased so that the fuel injection amount reduction-side correction amount falls within an appropriate allowable range. And managing means for controlling the fuel concentration in the blow-by gas introduced into the intake system.

  Examples of the lubricated portion of the internal combustion engine include a piston inner surface, a cylinder inner peripheral surface, a crank journal, and a valve mechanism.

  The operating state in which the correction amount of the fuel injection amount tends to be large is, for example, a warm idle operation of the internal combustion engine, that is, the internal combustion engine temperature is equal to or higher than a predetermined temperature, the engine speed is idling, and further acts on the internal combustion engine. It is assumed that the condition that the load is less than the specified condition is satisfied. Furthermore, the temperature of the internal combustion engine includes, for example, the temperature of cooling water of the internal combustion engine, the temperature of oil, and the like.

  According to this configuration, when the amount of oil circulation in the internal combustion engine is reduced during the warm operation, the amount of oil that touches the lubricated part is reduced, so that the amount of fuel vaporization in the circulation oil is small. Become. On the other hand, when the amount of oil circulation in the internal combustion engine is increased, the amount of oil that comes into contact with the lubricated portion increases, so that fuel vaporization in the circulating oil increases.

  When the oil circulation amount of the internal combustion engine is increased or decreased during the warm operation as in this configuration, it becomes possible to promote or suppress the vaporization of the fuel in the oil. The degree of dilution can be adjusted. As a result, the residual fuel in the circulating oil can be reduced as much as possible, and the original lubricating performance of the circulating oil can be maintained.

  Moreover, if the degree of oil dilution can be adjusted without controlling the fuel injection timing as described above, for example, with respect to the fuel injection timing, deterioration of exhaust properties such as generation of black smoke by suppressing fuel adhesion to the piston top surface. Therefore, it can be said that it is relatively easy to achieve both adjustment of the degree of oil dilution and improvement in exhaust property deterioration.

  Furthermore, as the degree of oil dilution can be reduced, the fuel concentration in the blow-by gas to be introduced into the intake system can be reduced, so that it is possible to reduce the fuel injection amount reduction amount correction amount, which leads to abnormalities in the fuel injection system. Judgment can be avoided.

  Preferably, during the increase / decrease process of the oil circulation amount by the management means, the process is terminated when the determination means determines that an operation state in which the fuel injection amount decrease correction amount is difficult to increase is reached. Is done.

  According to this configuration, when the processing that is being executed is terminated after the operating state is changed so that the fuel injection amount decrease-side correction amount is not easily increased, the temperature of the circulating oil and the temperature of the lubricated part become appropriate temperatures. The fuel is vaporized appropriately.

  Preferably, the determination means determines that the reduction amount correction amount of the fuel injection amount is likely to increase when the internal combustion engine is in a warm idle operation, and the fuel is detected when the other operation is in progress. It is determined that the operation state is such that the reduction amount correction amount of the injection amount is hardly increased.

  In this configuration, an operation state in which the fuel injection amount reduction amount correction amount tends to be large or an operation state in which it is difficult to increase is specified.

  Preferably, the determination means is an operating state in which the reduction amount correction amount of the fuel injection amount is likely to increase when the engine speed of the internal combustion engine is less than the specified speed, the load is less than the specified value, and the engine temperature is more than the specified value. If the above condition is not satisfied, it is determined that the operating state is such that the reduction amount correction amount of the fuel injection amount is difficult to increase.

  In this configuration, an operation state in which the fuel injection amount reduction amount correction amount tends to be large or an operation state in which it is difficult to increase is specified.

  Preferably, after the execution of the oil circulation amount increase / decrease processing, the management means monitors the change in the fuel injection amount decrease correction amount, and diagnoses that the fuel injection system is abnormal when there is no change It is assumed that the processing is executed.

  In this configuration, as a precondition, the degree of oil dilution is adjusted by, for example, promoting or suppressing fuel vaporization in the circulating oil when the fuel injection amount reduction side correction amount is likely to increase. The fuel injection amount follows the change in the fuel concentration in the blowby gas by utilizing the change in the fuel concentration in the blowby gas as the fuel vaporization in the circulating oil is promoted or suppressed. By checking whether or not the amount of correction on the decrease side of the fuel is changed, whether or not the fuel injection system is malfunctioning is checked.

  Thus, since the vaporization promotion process or the vaporization suppression process is linked to the abnormality determination of the fuel injection system, the reliability of the abnormality determination is improved, and the abnormality can be notified accurately.

  This is because when the increase / decrease processing of the oil circulation amount is performed, the progress of fuel vaporization in the circulating oil changes and the fuel concentration in the blow-by gas introduced into the intake system changes, so the fuel injection amount Need to be corrected.

  Thus, even if the oil circulation amount increase / decrease process is performed, if the fuel injection amount decrease correction amount does not change, it is considered that an essential abnormality of the fuel injection system has occurred. However, if the reduction amount correction amount of the fuel injection amount changes with the increase / decrease processing of the oil circulation amount, it can be determined that the fuel injection system is normal.

  Thus, by creating a situation where the fuel injection amount needs to be corrected, the reliability of the abnormality determination of the fuel injection system is improved.

  Preferably, when the determination unit determines that the current operation state is an operation state in which the reduction amount correction amount of the fuel injection amount tends to be large, the reduction amount correction amount of the fuel injection amount is appropriately set. Monitoring process for checking whether or not the fuel is within a permissible range, and a vaporization promoting process that promotes the vaporization of fuel in the circulating oil by increasing the amount of oil circulation in the internal combustion engine when it is less than the lower limit value of the permissible range And a vaporization suppression process that suppresses fuel vaporization in the circulating oil by reducing the oil circulation amount when the fuel circulation amount is lower than the upper limit value of the allowable range and less than the abnormality determination threshold value of the fuel injection system, and the vaporization promotion. When the fuel injection amount decrease correction amount does not change after the execution of the processing or the vaporization suppression processing, the diagnostic processing for determining that the fuel injection system is abnormal is executed.

  In short, in this configuration, the degree of oil dilution is adjusted by, for example, promoting or suppressing fuel vaporization in the circulating oil when an operation state in which the fuel injection amount reduction side correction amount is likely to be large is achieved. ing. In addition, by utilizing the fact that the fuel concentration in the blow-by gas changes as the fuel vaporization in the circulating oil is promoted or suppressed, the fuel injection amount is corrected on the reduction side following the change in the fuel concentration in the blow-by gas. By checking whether the amount changes or does not change, the presence or absence of malfunction of the fuel injection system is checked.

  Thus, since the vaporization promotion process or the vaporization suppression process is linked to the abnormality determination of the fuel injection system, the reliability of the abnormality determination is improved, and the abnormality can be notified accurately.

  This is because when either one of the above treatments is performed, the progress of fuel vaporization in the circulating oil changes and the fuel concentration in the blow-by gas introduced into the intake system changes. Need to be corrected.

  Therefore, even if the vaporization promotion process or the vaporization suppression process is performed, it is considered that an essential abnormality of the fuel injection system has occurred unless the fuel injection amount reduction amount correction amount changes. However, if the reduction amount correction amount of the fuel injection amount changes with the increase / decrease processing of the oil circulation amount, it can be determined that the fuel injection system is normal.

  Thus, by creating a situation where the fuel injection amount needs to be corrected, the reliability of the abnormality determination of the fuel injection system is improved.

  Preferably, the oil circulation amount is adjusted to increase or decrease by controlling a pumping hydraulic pressure of an oil pump that pumps oil in an oil storage section provided in an internal combustion engine to the lubricated portion.

  In this configuration, the element that circulates oil is specified as the oil pump. Since this oil pump is an existing component provided in a general internal combustion engine, the present invention is advantageous in suppressing facility costs, such as the addition of dedicated components.

  According to the present invention, it is possible to control the degree of fuel vaporization in the circulating oil without sacrificing good combustion of the internal combustion engine.

  Further, according to the present invention, it is possible to control the degree of fuel vaporization in the circulating oil without sacrificing good combustion of the internal combustion engine, and to reduce the fuel injection amount by air-fuel ratio feedback control. It is possible to suppress erroneous determination in the process of determining whether there is an abnormality in the fuel injection system based on the correction amount.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.

  1 to 6 show an embodiment of the present invention. The internal combustion engine exemplified in this embodiment is, for example, a direct injection gasoline engine. First, a schematic configuration of this type of internal combustion engine will be described with reference to FIG.

  In FIG. 1, an in-line multi-cylinder internal combustion engine 1 is shown from the front side. Pistons 3 are housed in cylinders 2a provided in a row (in a direction perpendicular to the plane of FIG. 1) in the cylinder block 2 of the internal combustion engine 1 so as to be reciprocally displaceable in the vertical direction.

  This reciprocating motion of the piston 3 is converted into a rotational motion of the crankshaft 5 via the connecting rod 4. A combustion chamber 7 is defined by the top surface 3 a of the piston 3, the inner peripheral surface of the cylinder 2 a, and the cylinder head 6.

  Fuel is directly injected into the combustion chamber 7 from a fuel injection valve 10 attached to the cylinder head 6. Further, an intake port 6 a and an exhaust port 6 b of the cylinder head 6 are connected to the combustion chamber 7. A throttle valve 11 is provided in the middle of the intake passage 8 connected to the intake port 6a, and the intake air introduced into the combustion chamber 7 is metered by the throttle valve 11.

  The intake air introduced into the combustion chamber 7 when the intake valve 12 is opened is mixed with the fuel injected from the fuel injection valve 10 to become an air-fuel mixture. The air-fuel mixture is explosively burned by ignition of the spark plug 14 and then discharged from the combustion chamber 7 to the exhaust port 6b when the exhaust valve 13 is opened.

  A delivery pipe 15 is connected to the fuel injection valve 10, and fuel is supplied from the delivery pipe 15 with a predetermined pressure.

  The delivery pipe 15 is supplied with the fuel sucked up by the fuel pump 17 from the fuel tank 16. Note that the fuel pressure in the delivery pipe 15, that is, the fuel injection pressure of the fuel injection valve 10 can be adjusted, for example, by appropriately changing the discharge amount of the fuel pump 17.

  In this internal combustion engine 1, by supplying oil to the sliding contact portion between the piston 3 and the cylinder 2a, the connecting rod 4 and the bearing portion of the crankshaft 5, etc., friction at the sliding and rolling portions is reduced and the internal combustion engine 1 is reduced. Temperature control (cooling and heating) of each part is performed.

  Here, the outline of the lubrication system of the internal combustion engine 1 will be described. In short, oil in an oil pan 9 as an oil reservoir attached to the cylinder block 2 via a crankcase (not shown) is taken out by an oil pump 20 and is not shown, but for example, a main oil hole or a main gallery It is configured to be supplied to a lubricated part in the cylinder block 2 or a crank journal through a cylinder block-side oil supply path, and to be supplied to a lubricated part in the cylinder head 6 via a cylinder head-side oil supply path. Yes.

  The oil in the oil pan 9 is sucked by the oil pump 20 through a filter (not shown). A bypass passage 21 for returning oil to the oil pan 9 is provided on the oil discharge side of the oil pump 20, and a relief valve 22 that is opened and closed as necessary is provided in the bypass passage 21. Yes.

  The cylinder block 2 is provided with an oil jet nozzle 23. The oil jet nozzle 23 is equipped with a check valve (not shown). In the case of such an oil jet nozzle 23, for example, when a hydraulic pressure higher than a predetermined level is applied, the check valve is opened to jet the oil onto the inner surface of the piston 3 or the inner peripheral surface of the cylinder 2a. However, when a hydraulic pressure less than a predetermined value is applied, the check valve remains closed, so that oil cannot be injected.

  The oil that has lubricated and cooled the sliding contact portion between the cylinder 2 a and the piston 3 is scraped off from the inner peripheral surface of the cylinder 2 a as the piston 3 reciprocates, and finally returned to the oil pan 9.

  The oil collected in the oil pan 9 is circulated in the closed loop in order to be used again for the lubrication and temperature control. By such oil circulation, the temperature of the oil is gradually raised by the heat of each part of the internal combustion engine.

  By the way, the cylinder block 2 is provided with a blow-by gas communication passage 25 for guiding blow-by gas existing in the crankcase to the cylinder head 6. The cylinder head 6 is provided with a blow-by gas recirculation passage 26 for guiding the blow-by gas to the intake passage 8. The blow-by gas recirculation passage 26 is provided with a PCV valve 27 for preventing back-flow of blow-by gas.

  Such an internal combustion engine 1 is controlled by an ENG_ECU (Electronic Control Unit) 40 as a control device according to the present invention.

  The ENG_ECU 40 performs at least various control (air-fuel ratio control, fuel injection control, etc.) in the internal combustion engine 1, and has the same configuration and central processing as a general ECU as shown in FIG. The configuration includes a device (CPU), a program memory (ROM), a data memory (RAM), a non-volatile memory (backup RAM), and the like. The CPU, ROM, RAM, and backup RAM are not labeled.

  The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes various arithmetic processes based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores the calculation results of the CPU, data input from each sensor, and the like. The backup RAM is a nonvolatile memory that stores data to be saved when the internal combustion engine is stopped, for example. Memory.

  The ENG_ECU 40 manages various operations of the internal combustion engine by controlling necessary elements based on input information from appropriate sensors.

  The input interface (reference number omitted) of the ENG_ECU 40 includes, for example, a water temperature sensor 51, an intake air amount sensor 52, a throttle opening sensor 53, a crank position sensor (engine speed sensor) 54, an oxygen sensor 55 (only shown in FIG. 2), etc. Is connected.

  The intake air amount sensor 52 is provided upstream of the throttle valve 11 in the intake passage 8 connected to the intake port 6a of the internal combustion engine 1. The oxygen sensor 55 is provided upstream of a catalyst device (not shown) in an exhaust passage (not shown) connected to the exhaust port 6b of the internal combustion engine 1.

  For example, the fuel injection valve 10, the fuel pump 17, the throttle motor 18 of the throttle valve 11 (shown only in FIG. 2), the igniter 19 of the spark plug 14 (shown only in FIG. 2), and the oil pump 20, a relief valve 22 and the like are connected.

  The elements connected to each interface are only those related to the characteristics of the present invention, and descriptions and explanations of elements not directly related to the characteristics of the present invention are omitted.

  Next, an example of operation control of the internal combustion engine 1 described above will be described.

  For example, during low and medium load operation, the fuel injection amount and the like are controlled so that the air-fuel ratio A / F becomes the stoichiometric air-fuel ratio (for example, “A / F = 14.5”).

  Further, during high load operation, the fuel injection amount and the like are controlled so that the air-fuel ratio A / F is, for example, near the output air-fuel ratio (for example, “A / F = 12”).

  During these operations, feedback control of the fuel injection amount obtained based on the deviation tendency between the actual air-fuel ratio and the target air-fuel ratio, that is, air-fuel ratio feedback control is performed.

  In addition, in this air-fuel ratio feedback control, when the fuel injection amount reduction side correction amount is less than the abnormality determination threshold value, the fuel injection system (fuel injection valve 10 and the like) is diagnosed as being normal, while the fuel injection amount When the reduction amount correction amount is greater than or equal to the abnormality determination threshold, the abnormality is reported after diagnosing that the fuel injection system (fuel injection valve 10 or the like) is abnormal.

  As a form of this abnormality notification, for example, a MIL (Malfunction Indicator Lamp) indicating that the fuel injection system is abnormal can be turned on, but other forms are also possible.

  Next, portions to which the features of the present invention are applied will be described.

  In short, during operation that tends to increase the fuel injection amount decrease correction amount by air-fuel ratio feedback control, that is, during warm idle operation, increase or decrease oil circulation amount to promote or suppress fuel vaporization in circulating oil. Thus, the degree of oil dilution is controlled, and the fuel injection system is devised so as to avoid being erroneously determined as abnormal.

  As described in the prior art, in the abnormality diagnosis of the fuel injection system described above, there is a case where an abnormality is accurately determined due to an essential malfunction of the fuel injection system, and a case where the fuel injection system is normal. Regardless, there is a case where it is erroneously determined to be abnormal due to the introduction of the intake system of blow-by gas.

  Therefore, in this embodiment, in short, when the current operation state is a warm idle operation in which the fuel injection amount reduction side correction amount in the air-fuel ratio feedback control tends to be large, the fuel injection amount reduction side correction amount is A monitoring process for checking whether or not the fuel is within the allowable range, and a vaporization promotion process that promotes the vaporization of the fuel in the circulating oil by increasing the amount of oil circulation in the internal combustion engine 1 when it is less than the lower limit value of the allowable range. And a vaporization suppression process that suppresses fuel vaporization in the circulating oil by reducing the oil circulation amount when the fuel circulation amount is lower than the upper limit value of the allowable range and less than the abnormality determination threshold value of the fuel injection system, and the vaporization promotion. A diagnostic process for determining that the fuel injection system is abnormal when the fuel injection amount decrease correction amount does not change after the process or the vaporization suppression process is executed. It is way.

  Specifically, this will be described in detail with reference to FIGS.

  FIG. 3 is a flowchart mainly showing the operation of the ENG_ECU 40 as the control device according to the present invention. This flowchart is entered, for example, at regular intervals.

  First, in step S1, the water temperature Tw, the engine speed NE, the load KL, and the fuel injection amount decrease side correction amount Δq are read. Here, information for determining whether or not the current operation state is a warm idle operation is taken in.

  In subsequent step S2, it is determined whether or not the current water temperature Tw exceeds a predetermined specified value TwX. The specified value TwX is set to a temperature that is a boundary between the cold operation and the warm operation of the internal combustion engine 1.

  Here, when the current water temperature Tw is lower than the specified value TwX, the cold operation is being performed. Therefore, a negative determination is made in step S2, and the process exits this flowchart. However, if the current water temperature Tw exceeds the specified value TwX, the warm operation is being performed, so an affirmative determination is made in step S2 and the process proceeds to the subsequent step S3.

  In step S3, it is determined whether or not the engine speed is idling. Here, if it is not idling, a negative determination is made in step S3 and the process exits this flowchart. If idling is determined, an affirmative determination is made in step S3 and the process proceeds to the subsequent step S4.

  In short, in steps S2 and S3 described above, it is checked whether or not the current operation state is a warm idle operation.

  In this warm idling operation, even if the fuel injection amount decrease by air-fuel ratio feedback control is small compared with that during medium and high load operation, the fuel injection amount during warm idling operation is small compared to during medium and high load operation. Therefore, the decrease side correction amount Δq is larger than that during medium and high load operation. In consideration of this point, in steps S2 and S3, it is checked whether or not the operation is a warm idle operation in which the fuel injection amount reduction side correction amount Δq by the air-fuel ratio feedback control is increased.

  In step S4, it is determined whether or not the fuel injection amount reduction side correction amount Δq is equal to or greater than a lower limit Δqmin of an appropriate allowable range.

  Here, if Δq <Δqmin, a negative determination is made in step S4, and the process exits this flowchart. If Δq ≧ Δqmin, an affirmative determination is made in step S4, and the subsequent step S5. Migrate to

  In this step S5, it is determined whether or not the fuel injection amount reduction side correction amount Δq is equal to or greater than the upper limit value Δqmax of the allowable range. This upper limit value Δqmax is set to a value that is appropriately smaller than the abnormality determination threshold value ΔqNG of the fuel injection system.

  Here, if Δq <Δqmax, that is, if there is a margin up to the abnormality determination threshold value ΔqNG, a negative determination is made in step S5 and the flow proceeds to the following steps S6 to S10, but Δq ≧ Δqmax. In this case, that is, when there is no margin to the abnormality determination threshold value ΔqNG, an affirmative determination is made in step S5, and the flow proceeds to the following steps S11 to S16.

  First, the processing of steps S6 to S10 will be described.

  In step S6, a vaporization promotion process is executed. This vaporization promotion process is to increase the amount of oil circulation in the internal combustion engine 1, that is, the amount of oil supplied to the lubricated parts in the cylinder block 2 and the cylinder head 6. This oil circulation amount is adjusted to increase or decrease by controlling the pressure hydraulic pressure of the oil pump 20.

  When this vaporization promotion process is executed, the amount of oil that comes into contact with the lubricated parts in the cylinder block 2 and the cylinder head 6 that are at a certain high temperature increases, so that the fuel vaporization in the circulating oil proceeds. The fuel concentration in the blow-by gas gradually increases.

  After step S6, in subsequent step S7, it is determined whether or not the fuel injection amount decrease side correction amount Δq has changed. Here, in short, it is examined whether or not the fuel injection system is functioning normally.

  This is because if the amount of oil circulation is increased by executing the vaporization promotion process, the fuel (HC) concentration in the blow-by gas increases, so if the fuel injection system is normal, the fuel injection amount is reduced. Therefore, the decrease side correction amount Δq should be large. However, if the fuel injection system is abnormal such as a malfunction, the fuel injection amount decrease side correction amount Δq does not change.

  Here, when it has not changed, an affirmative determination is made in step S7, and the process proceeds to the subsequent step S8. In step S8, it is determined that the fuel injection system is abnormal, and the process proceeds to an abnormality notification process.

  However, if it has changed, a negative determination is made in step S7, and the process proceeds to step S9. In step S9, as in step S5, it is determined whether or not the fuel injection amount reduction side correction amount Δq is equal to or greater than the upper limit value Δqmax of the allowable range.

  Here, if Δq ≧ Δqmax, an affirmative determination is made in step S9, the process proceeds to the following step S17, and the vaporization promotion process is terminated. If Δq <Δqmax, the above step is performed. A negative determination is made in S9, and the routine proceeds to the subsequent step S10.

  In this step S10, it is determined whether or not the fuel injection amount decrease side correction amount Δq is less than the lower limit value Δqmin of the normal range.

  For reference, the fuel injection amount reduction correction amount Δq decreases with the passage of the execution time of the vaporization promotion process. The reason is that as the fuel vaporization in the circulating oil proceeds and the residual fuel in the circulating oil gradually decreases, the fuel concentration in the blow-by gas gradually decreases. In short, in step S10, this phenomenon is examined.

  If Δq ≧ Δqmin, a negative determination is made in step S10, and the process returns to step S7. If Δq <Δqmin, an affirmative determination is made in step S10, and step S17. Then, the vaporization promotion process is terminated.

  On the other hand, the process of said step S11-S16 is demonstrated.

  In step S11, a vaporization suppression process is executed. This vaporization suppression process is to reduce the amount of oil circulation in the internal combustion engine 1, that is, the amount of oil supplied to the lubricated parts in the cylinder block 2 and the cylinder head 6. This oil circulation amount is adjusted to increase or decrease by controlling the pressure hydraulic pressure of the oil pump 20.

  When this vaporization suppression process is executed, the amount of oil that comes into contact with the lubricated parts in the cylinder block 2 and the cylinder head 6 that are at a certain high temperature decreases, so that the fuel in the circulating oil is difficult to vaporize. Accordingly, the fuel concentration in the blow-by gas gradually decreases, and the fuel injection amount decrease side correction amount Δq gradually decreases.

  After step S11, in the subsequent step S12, the engine speed NE and the load KL are read. In step S13, it is determined whether or not the engine speed NE is idling.

  Here, in the case of idling, an affirmative determination is made in step S13, and the process proceeds to the subsequent step S14. However, in the case of not idling, a negative determination is made in step S13, and the process proceeds to step S17 described below. . In this step S17, the vaporization suppression process is terminated, and then this flowchart is exited.

  In step S14, it is determined whether or not the fuel injection amount decrease side correction amount Δq has changed. Here, in short, it is examined whether or not the fuel injection system is functioning normally.

  For example, when the oil circulation amount is reduced as shown in FIG. 4A by executing the vaporization suppression process, the concentration of fuel (HC) in the blow-by gas decreases as shown in FIG. 4C. If the fuel injection system is normal, the fuel injection amount is increased as shown by the solid line in FIG. 4B, and the decrease side correction amount Δq should be reduced. However, if the fuel injection system is abnormal, such as a malfunction, as shown by the broken line in FIG. 4B, the fuel injection amount decrease side correction amount Δq does not change.

  Here, when it has not changed, an affirmative determination is made in step S14, and the process proceeds to step S15. In step S15, it is determined that the fuel injection system is abnormal, and the process proceeds to an abnormality notification process.

  However, if it has changed, a negative determination is made in step S14, and the process proceeds to step S16. In this step S16, it is determined whether or not the fuel injection amount decrease side correction amount Δq is less than the lower limit Δqmin of the allowable range.

  If Δq ≧ Δqmin, a negative determination is made in step S16 and the process returns to step S12. If Δq <Δqmin, an affirmative determination is made in step S16 and the following steps are performed. The process proceeds to S17 and the vaporization suppression process is terminated. Thereafter, the process exits this flowchart.

  As is clear from the above operation description, each step executed by the ENG_ECU 40 corresponds to each means described in the claims.

  Next, a series of control operations will be exemplified and described with reference to the time charts shown in FIGS.

  Normally, as shown in FIG. 5 and FIG. 6 (a), during the operation in the high speed / high load state, the operation in the middle / medium load state, and the warm idle operation in the stop state, the oil circulation amount is As shown in FIGS. 5 and 6 (c), the fuel consumption tends to decrease in the order described, and the fuel injection amount decrease side correction amount Δq is as shown in FIGS. 5 and 6 (b). Shows a tendency to increase in the order described above.

  Here, the case where it transfers to warm idle driving | running | working in the state which oil dilution has not progressed so much is demonstrated.

  In this case, as shown in the solid line of FIG. 5B, the fuel injection amount decrease side correction amount Δq is less than the allowable range upper limit value Δqmax when it exceeds the allowable range lower limit value Δqmin. As shown in 5 (c), the vaporization promotion process is started.

  As a result, the fuel vaporization in the circulating oil gradually proceeds and the fuel concentration in the blow-by gas gradually increases, so that the fuel injection amount reduction side correction amount Δq gradually increases.

  In addition, since the amount of residual fuel in the circulating oil can be reduced as much as possible by the above-described vaporization promoting process, the lubricating performance of the circulating oil can be properly restored.

  At this time, if the above-described vaporization promotion processing is not performed, the fuel injection amount decrease-side correction amount Δq tends to be as shown by the broken line in FIG. 5B, and the fuel injection amount decrease-side correction amount Δq becomes small. However, since the residual fuel amount in the circulating oil remains large, it can be said that the lubricating performance of the circulating oil is difficult to recover.

  When the predetermined time elapses, the residual fuel to be vaporized in the oil gradually decreases, and conversely, the fuel concentration in the blow-by gas gradually decreases, and the fuel injection amount decreases accordingly. The side correction amount Δq tends to gradually decrease. Thus, when the fuel injection amount decrease-side correction amount Δq is less than the lower limit Δqmin of the allowable range, the execution of the vaporization promotion process is terminated. Accordingly, as shown by the solid line in FIG. 5B, the fuel injection amount decrease side correction amount Δq is abruptly reduced.

  On the other hand, the case where it shifts to warm idle operation in the state where oil dilution progressed excessively is explained.

  In this case, as shown by the solid line in FIG. 6B, the fuel injection amount reduction side correction amount Δq is less than the upper limit value Δqmax of the allowable range when it first exceeds the lower limit value Δqmin of the allowable range. As shown in FIG. 6C, the vaporization promotion process is started.

  As a result, fuel vaporization in the circulating oil gradually proceeds and the fuel concentration in the blow-by gas gradually increases, so that the fuel injection amount reduction side correction amount Δq further increases. As a result, when the upper limit value Δqmax of the allowable range is reached, as shown in FIG. 6C, execution of the vaporization suppression process is started.

  As a result, fuel vaporization in the circulating oil is suppressed and the fuel concentration in the blow-by gas becomes low, so that the fuel injection amount reduction side correction amount Δq becomes small. Therefore, it is not necessary to exceed the abnormality determination threshold value ΔqNG.

  At this time, if the above-described vaporization suppression process is not performed, the fuel injection amount reduction side correction amount Δq is not shown, but it is highly likely that the abnormality determination threshold value ΔqNG is exceeded. It can be said that there is a case.

  Even after the predetermined time has elapsed, the residual fuel in the oil does not increase so much, so the fuel concentration in the blow-by gas gradually decreases, and the fuel injection amount decrease side correction amount Δq gradually decreases accordingly. Become. Thus, when the fuel injection amount reduction side correction amount Δq becomes less than the lower limit value Δqmin of the allowable range, as shown by the solid line in FIG. 6B, the execution of the vaporization suppression process is terminated. The decrease side correction amount Δq once increases rapidly and then decreases.

  As described above, in the embodiment to which the feature of the present invention is applied, the oil circulation amount is increased or decreased during the warm idle operation in which the fuel injection amount reduction side correction amount Δq by the air-fuel ratio feedback control is relatively large. By promoting or suppressing vaporization of the fuel in the circulating oil, the fuel injection amount reduction side correction amount Δq is kept within an allowable range that does not increase to the fuel injection system abnormality determination threshold value ΔqNG.

  As a result, even if the oil dilution progresses by the cold operation until reaching the warm idle operation, the vaporization state of the fuel in the circulating oil can be controlled when the warm idle operation is started. Control is facilitated, and the circulating oil can be restored to its original lubricating performance.

  In addition, the fuel injection system can be determined to be normal if the fuel injection amount decrease side correction amount Δq changes following the change in the fuel concentration in the blowby gas, but if it does not change, the fuel injection system It becomes possible to clearly determine that it is abnormal. Thereby, it is possible to avoid erroneously determining that the fuel injection system is abnormal due to oil dilution.

  In addition, this invention is not limited only to the said embodiment, All the deformation | transformation and application included in the range equivalent to the claim and the said range are possible. Examples are given below.

  (1) In the above embodiment, a cylinder direct injection gasoline engine is given as an example of an internal combustion engine to which the present invention is applied. However, a diesel engine, a flexible fuel vehicle (Flexible Fuel Vehicle) is also used. The present invention can be applied. Further, the present invention can be applied to a type in which in-cylinder direct injection and port injection are used in combination or a type in which only a port injection type is used.

  (2) In the above embodiment, an example in which the oil circulation amount is controlled by controlling the pressure hydraulic pressure of the oil pump 20 is given. However, the present invention is not limited thereto. For example, the oil circulation amount is controlled by returning the oil discharged by the oil pump 20 from the bypass passage 21 to the oil pan 9 by controlling the opening of the relief valve 22. It is also possible to limit this.

  (3) In the above embodiment, the fuel concentration in the blow-by gas is controlled by increasing / decreasing the oil circulation amount, and an abnormality determination of the fuel injection system can be accurately performed in conjunction with the control. ing.

  However, the present invention is not related to the abnormality determination process of the fuel injection system, and simply adjusts the amount of oil dilution by adjusting the oil circulation amount during warm operation of the internal combustion engine 1, for example, during warm idle operation. It is also possible to implement as a form of active control.

  In short, the present invention is completely different from the technical idea of suppressing the progress of oil dilution by performing fuel injection control that reduces liner wet and increases piston wet as in the conventional example.

  Therefore, it is possible not only to perform normal fuel injection control that is generally suitable for warm idle operation, but also to control fuel injection at a timing that reduces piston wetness. Therefore, the combustion state of the internal combustion engine 1 can be improved, and the deterioration of the exhaust properties caused by the fuel adhering to the top surface 3a of the piston 3 can be improved.

  As described above, it is possible to improve the deterioration of the exhaust property at the fuel injection timing while reducing the oil dilution degree by the increase / decrease control of the oil circulation amount.

  (4) In the above embodiment, the internal combustion engine 1 of the type storing oil in the oil pan 9 is taken as an example, but the present invention can also be applied to, for example, a dry sump type internal combustion engine.

  In the case of a dry sump type internal combustion engine, an oil storage part is installed separately from the internal combustion engine, and oil and blow-by gas returning to the crank chamber are taken out by an oil pump and collected in the oil storage part. Therefore, even in a dry sump type internal combustion engine, the vaporization suppression process for reducing the oil circulation amount and the vaporization promotion process for increasing the oil circulation amount are performed by controlling the oil pressure of the oil pump, as in the above embodiment. be able to.

It is a figure which shows schematic structure in one Embodiment of ENG_ECU as a control apparatus of the internal combustion engine which concerns on this invention. It is a block diagram which shows schematic structure of ENG_ECU of FIG. FIG. 3 is a flowchart used for explaining operations by the ENG_ECU in FIG. 2. (A)-(c) is a figure which shows the relationship between the oil circulation amount of the internal combustion engine of FIG. 1, the reduction | decrease side correction amount of a fuel injection amount, and HC (fuel) density | concentration in blow-by gas. (A)-(c) is a figure which shows the relationship between the vehicle speed, the reduction | decrease side correction amount of a fuel injection amount, and the oil circulation amount in case oil dilution is not progressing so much. (A)-(c) is a figure which shows the relationship between the vehicle speed, the reduction | decrease side correction amount of a fuel injection amount, and the oil circulation amount in case oil dilution is progressing excessively.

Explanation of symbols

1 Internal combustion engine
2a cylinder
3 Piston
3a Piston top surface
6a Intake port
6b Exhaust port
7 Combustion chamber
8 Intake passage
9 Oil pan 10 Fuel injection valve 11 Throttle valve 20 Oil pump 23 Oil jet nozzle 40 ENG_ECU (control device)
51 Water temperature sensor 52 Intake air amount sensor 53 Throttle opening sensor 54 Crank position sensor 55 Oxygen sensor

Claims (8)

A control device that supplies oil to a lubricated part of an internal combustion engine and performs an oil circulation process that collects the oil and supplies it to the lubricated part again.
During the warm operation of the internal combustion engine, if necessary, a vaporization promotion process for increasing the amount of oil circulation to promote the vaporization of fuel in the oil, and a vaporization of fuel in oil by reducing the amount of oil circulation. A control device for an internal combustion engine, comprising management means for executing a vaporization suppression process to be suppressed. A control device that supplies oil to a lubricated part of an internal combustion engine and performs an oil circulation process that collects the oil and supplies it to the lubricated part again.
Air-fuel ratio control means for feedback-correcting the fuel injection amount with respect to the basic fuel injection amount based on the deviation between the actual air-fuel ratio and the target air-fuel ratio;
A determination means for examining whether or not the operating state in which the reduction amount correction amount of the fuel injection amount is likely to increase;
When the determination means determines that the fuel injection amount reduction-side correction amount is likely to be large, the oil circulation amount is set so that the fuel injection amount reduction-side correction amount falls within an appropriate allowable range. And a control means for controlling the fuel concentration in the blow-by gas introduced into the intake system by increasing or decreasing the control system. The control apparatus for an internal combustion engine according to claim 2,
During the process of increasing / decreasing the oil circulation amount by the management means, the process is terminated when the determination means determines that an operation state in which the fuel injection amount decrease-side correction amount is difficult to increase is achieved. Control device for internal combustion engine. The control device for an internal combustion engine according to claim 2 or 3,
The determination means determines that the reduction amount correction amount of the fuel injection amount is likely to increase when the internal combustion engine is in a warm idle operation, and determines the fuel injection amount when the other operation is in progress. A control device for an internal combustion engine, characterized in that it is determined that the operating state is such that the reduction side correction amount does not easily increase. The control device for an internal combustion engine according to claim 2 or 3,
The determination means is an operating state in which the reduction amount correction amount of the fuel injection amount is likely to increase when the engine speed of the internal combustion engine satisfies the conditions that the engine speed is equal to or lower than the specified speed, the engine load is equal to or lower than the specified value, and the engine temperature is equal to or higher than the specified value. And determining that the fuel injection amount reduction side correction amount is difficult to increase when the condition is not satisfied. The control apparatus for an internal combustion engine according to any one of claims 1 to 5,
The management means, after execution of the oil circulation amount increase / decrease process, monitoring process for monitoring the change of the fuel injection amount decrease side correction amount;
A control apparatus for an internal combustion engine, which executes a diagnosis process for determining that the fuel injection system is abnormal when there is no change. The control apparatus for an internal combustion engine according to any one of claims 2 to 5,
When the determination unit determines that the current operation state is an operation state in which the reduction amount correction amount of the fuel injection amount tends to be large, the reduction amount correction amount of the fuel injection amount is an appropriate allowable range. Monitoring process to check whether or not
A vaporization promoting process for promoting the vaporization of fuel in the circulating oil by increasing the amount of oil circulation in the internal combustion engine when less than the lower limit of the allowable range;
A vaporization suppression process that suppresses fuel vaporization in the circulating oil by reducing the amount of oil circulation when the upper limit value of the allowable range is exceeded and less than the abnormality determination threshold value of the fuel injection system;
An internal combustion engine characterized by executing a diagnosis process for determining that the fuel injection system is abnormal when the fuel injection amount reduction correction amount does not change after the vaporization promotion process or the vaporization suppression process is performed. Control device. The control apparatus for an internal combustion engine according to any one of claims 1 to 7,
The control apparatus for an internal combustion engine, wherein the oil circulation amount is adjusted to be increased or decreased by controlling a pumping hydraulic pressure of an oil pump that pumps oil in an oil storage portion equipped in the internal combustion engine to the lubricated portion. .

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