JP4604842B2 - Abnormality judgment device for fuel system of internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection means (in-cylinder injector) for injecting fuel at a high pressure toward the inside of a cylinder, a fuel injection means (intake passage injection injector) for injecting fuel into an intake passage or an intake port, In particular, the present invention relates to an apparatus for accurately determining an abnormality in a high-pressure fuel system.

  A first fuel injection valve (in-cylinder injector) for injecting fuel into a combustion chamber of a gasoline engine, and a second fuel injection valve (intake passage injection) for injecting fuel into an intake passage or an intake port In-cylinder injectors and intake manifold injectors are known in accordance with the engine speed and the load on the internal combustion engine. Further, a direct engine including only a fuel injection valve (in-cylinder injector) for injecting fuel into a combustion chamber of a gasoline engine is also known. In a high-pressure fuel system including an in-cylinder injector, fuel whose fuel pressure has been increased by a high-pressure fuel pump is supplied to the in-cylinder injector via a delivery pipe, and the in-cylinder injector is connected to each cylinder of the internal combustion engine. High pressure fuel is injected into the combustion chamber.

  A diesel engine having a common rail fuel injection system is also known. In this common rail fuel injection system, fuel whose fuel pressure has been increased by a high pressure fuel pump is stored in a common rail, and high pressure fuel is injected from the common rail into the combustion chamber of each cylinder of a diesel engine by opening and closing an electromagnetic valve.

  In order to bring the fuel in such an internal combustion engine into a high pressure state, a high pressure fuel pump that drives a cylinder by a cam provided on a drive shaft connected to a crankshaft of the internal combustion engine is used.

  Japanese Laid-Open Patent Publication No. 10-176593 (Patent Document 1) discloses a fuel pressure diagnostic device for a fuel injection device for an internal combustion engine that can diagnose the presence or absence of abnormality in fuel pressure with high accuracy. The fuel pressure diagnostic device is provided for each cylinder and is stored in the pressure accumulating means, the fuel pressure feeding means for pumping the fuel supplied to each cylinder of the internal combustion engine, the pressure accumulating means for storing the fuel pumped from the fuel pressure feeding means. A fuel injection means for intermittently injecting the fuel into the internal combustion engine, a fuel pressure sensor for detecting the pressure of the fuel stored in the pressure accumulation means, and a pressure pumping means based on the fuel pressure detected by the fuel pressure sensor. Pressure abnormality diagnosis in a fuel injection device for an internal combustion engine comprising pressure control means for controlling the pressure of fuel stored in the pressure accumulating means, and pressure abnormality diagnosis means for diagnosing whether there is an abnormality in fuel pressure controlled by the pressure control means The means diagnoses whether there is an abnormality in the fuel pressure when each fuel injection means is in an inoperative state.

According to the fuel pressure diagnostic apparatus of the fuel injection device for an internal combustion engine, the fuel that pumps the fuel that the fuel pumping means supplies to each cylinder of the internal combustion engine is stored in the pressure accumulating means. The fuel stored in the pressure accumulating means is intermittently injected into each cylinder by the fuel injection means provided for each cylinder. The pressure of the fuel stored in the pressure accumulating means is detected by a fuel pressure sensor, and the fuel pressure feeding means is controlled by the pressure control means based on the detected fuel pressure. Here, when each fuel injection means is in an inoperative state, the fuel pressure controlled by the pressure control means is diagnosed by the pressure abnormality diagnosis means. As a result, the presence or absence of an abnormality in the fuel pressure is diagnosed based on the fuel pressure that is not affected by the pressure fluctuation caused by intermittent fuel injection. That is, in an operating state in which each fuel injection unit intermittently injects fuel, the fuel pressure stored in the pressure storage unit varies within a certain pressure range. Therefore, it becomes difficult to detect the pressure at which the fuel pressure is actually controlled, and it becomes difficult to detect the outflow of the fuel pressure due to the failure of the fuel injection means. Here, since the abnormality diagnosis of the fuel pressure is performed when the fuel injection means is in the non-operating state, it is possible to diagnose the presence or absence of the abnormality of the fuel pressure based on the fuel pressure without the pressure fluctuation due to the intermittent injection.
JP-A-10-176593

  However, an internal combustion engine having an in-cylinder injector that injects fuel at a high pressure into the cylinder and an intake passage injector that injects fuel into the intake passage or the intake port is required for the internal combustion engine. The fuel injection between the in-cylinder injector and the intake manifold injector is shared according to the performance to be performed. For example, when obtaining the homogeneity of combustion, fuel is injected only from the intake manifold injector. Even in such a case, in the high-pressure fuel system that supplies high-pressure fuel to the in-cylinder injector, the fuel is supplied by the high-pressure pump so that the fuel can be immediately injected from the in-cylinder injector based on a command from the control device. Is raised to about 8 to 13 MPa (however, fuel is not injected from the in-cylinder injector). At this time, the high-pressure fuel does not inject (consumes) the fuel, and tends to increase in temperature due to high temperature due to heat from the internal combustion engine. In such a case, even if an abnormality of the high-pressure fuel system is detected based on the excessive increase in fuel pressure, the high-pressure fuel system itself is normal and erroneously determined. The fuel pressure diagnostic device disclosed in Patent Document 1 only discloses that an abnormality diagnosis of the fuel pressure is performed when the fuel injection means is in an inoperative state, and an in-cylinder injector, an intake passage injection injector, This is applied to an internal combustion engine having an internal combustion engine in which the in-cylinder injector (high pressure side) does not inject fuel and the intake passage injector (low pressure side) injects fuel to operate the internal combustion engine. I can't.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is, for example, a fuel injection unit that injects fuel into a cylinder by being supplied with fuel by a high-pressure fuel system including a high-pressure pump, An object of the present invention is to provide a determination device capable of accurately determining an abnormality in a fuel system in an internal combustion engine including at least a fuel injection means for injecting fuel into an intake passage or an intake port.

  The abnormality determination device according to the first invention has at least two fuel systems, and detects an abnormality in the fuel system of the internal combustion engine to which fuel is supplied by the fuel injection means connected to each fuel system. In this internal combustion engine, even if the fuel is not injected by the first fuel injection means and the fuel is injected by the second fuel injection means other than the first fuel injection means, the first fuel injection means The pressure of the fuel in the first fuel system that supplies fuel to the fuel injection means is controlled to a desired pressure. The abnormality determination device compares the detected fuel pressure with a predetermined threshold value by detecting means for detecting the fuel pressure in the first fuel system, thereby detecting the first fuel system. Pressure increase determination means for determining whether or not the fuel pressure is excessively increased, and if the fuel is not injected by the first fuel injection means, the pressure increase determination means And prohibiting means for prohibiting the determination by.

  According to the first invention, the determination means on the pressure increase side, for example, when the pressure of the fuel system becomes abnormally high (when the detected fuel pressure becomes higher than a predetermined threshold value), It is determined that the fuel pressure is abnormally high. The determination means on the pressure increase side is prohibited by the prohibiting means when the fuel is not injected by the first fuel injection means. In this internal combustion engine, even if the fuel is not injected by the first fuel injection means, the first combustion injection means (for example, an in-cylinder injector that injects high-pressure fuel into the cylinder) Fuel is injected by two combustion injection means (for example, an intake passage injector that injects into the intake passage), and from this state, the start of fuel injection using the in-cylinder injector is commanded. Sometimes the fuel pressure in the first fuel system is maintained at the desired pressure for fuel injection in order to immediately inject high pressure fuel. On the other hand, fuel is not injected from the in-cylinder injector, and the fuel in the first fuel system tends to increase in temperature due to heat from the internal combustion engine. For this reason, the fuel pressure in the first fuel system may exceed the upper limit threshold value even though the first fuel system is operating normally. Therefore, when fuel is injected only from the intake manifold injector, the abnormality of the first fuel system is accurately determined without determining the abnormality of the first fuel system on the fuel pressure increase side. be able to. As a result, for example, an internal combustion engine having at least fuel injection means for injecting fuel into a cylinder supplied with fuel by a high-pressure fuel system including a high-pressure pump, and fuel injection means for injecting fuel into an intake passage or an intake port It is possible to provide a determination device that can accurately determine abnormality of a fuel system in an engine.

  In the abnormality determination device according to the second invention, in addition to the configuration of the first invention, the first fuel injection means is means for injecting high-pressure fuel supplied from the first fuel system into the cylinder. And the second fuel injection means includes means for injecting the fuel supplied from the second fuel system into the intake passage. The determination means on the pressure increase side is configured to determine that the fuel pressure in the first fuel system is abnormally increased when the detected fuel pressure is higher than a predetermined threshold value. Including means.

  According to the second invention, when the abnormality determination is not prohibited by the prohibiting unit, the determination unit on the pressure increase side causes the first fuel to be detected when the detected fuel pressure is higher than a predetermined threshold value. It can be determined that this is an abnormal state in which the fuel pressure in the system rises excessively.

  In addition to the configuration of the first invention, the abnormality determination device according to the third invention compares the detected fuel pressure with a predetermined threshold regardless of the injection mode of the fuel injection means. Thus, it further includes pressure-decreasing-side determining means for determining whether or not the fuel pressure in the first fuel system is in an abnormal state that excessively decreases.

  According to the third invention, the determination means on the pressure drop side is not prohibited from making an abnormality determination by the prohibiting means due to the injection mode of the fuel injection means. That is, even when the first fuel injection means does not inject fuel, even if the first fuel system receives heat from the internal combustion engine and becomes high temperature and high pressure, an abnormality on the pressure drop side can be accurately determined. For this reason, for example, an abnormality in which the fuel pressure in the first fuel system is excessively reduced, such as a leak from the fuel system piping, can be determined regardless of the injection mode of the fuel injection means. .

  In the abnormality determination device according to the fourth invention, in addition to the configuration of the third invention, the first fuel injection means is means for injecting the high-pressure fuel supplied from the first fuel system into the cylinder. And the second fuel injection means includes means for injecting the fuel supplied from the second fuel system into the intake passage. The pressure drop-side determination means is for determining that the detected fuel pressure is lower than a predetermined threshold value, and that the fuel pressure in the first fuel system is abnormally low. Including means.

  According to the fourth invention, regardless of the injection mode of the fuel injection means, when the pressure of the detected fuel is lower than a predetermined threshold value, the determination means on the pressure reduction side It can be determined that the fuel pressure is abnormally low.

  In the abnormality determination device according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the first fuel system includes a high-pressure pump that makes the fuel a high pressure. The determination means on the pressure drop side predetermines the detected fuel pressure when the detected fuel pressure is lower than the target pressure in the first fuel system and the high-pressure pump is driven. Means for determining an abnormal condition in which the fuel pressure in the first fuel system is excessively reduced when the threshold value is lower than the threshold value is included.

  According to the fifth invention, regardless of the injection mode of the fuel injection means, even when the detected fuel pressure is lower than the target pressure and the high-pressure pump is also driven, the threshold for abnormality determination When the value is lower than the value, it can be determined that the fuel pressure in the first fuel system is in an abnormal state in which the pressure is excessively reduced.

  In the abnormality determination device according to the sixth invention, in addition to the configuration of any one of the first to fifth inventions, the first fuel injection means is an in-cylinder injector, and the second fuel injection means Is an intake passage injector.

  According to a sixth aspect of the present invention, in an internal combustion engine that shares an injected fuel by separately providing an in-cylinder injector that is a first fuel injection means and an intake passage injection injector that is a second fuel injection means. It is possible to provide a determination device that can accurately determine a system abnormality.

  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 an engine fuel supply system 10 controlled by an engine ECU (Electronic Control Unit) which is a control device according to an embodiment of the present invention. This engine is a V-type 8-cylinder gasoline engine, and includes an in-cylinder injector 110 that injects fuel into the cylinder of each cylinder, and an intake passage injector 120 that injects fuel into the intake passage of each cylinder. Have The present invention is not limited to such an engine and may be applied to other types of gasoline engines (V type 6 cylinder, inline 6 cylinder, inline 4 cylinder, etc.). Furthermore, the number of high-pressure fuel pumps is not limited to two, but may be one or more.

  As shown in FIG. 1, the fuel supply system 10 is provided in a fuel tank, and is driven by a feed pump 100 that supplies fuel at a low pressure (pressure regulator pressure of about 400 kPa) and a first cam 210. The high-pressure fuel is supplied to the second high-pressure fuel pump 300 driven by the second cam 310 and the in-cylinder injector 110 that are different in discharge phase from the first high-pressure fuel pump 200 and the first cam 210. High pressure delivery pipe 112 provided for each of the left and right banks, four in-cylinder injectors 110 for each of the left and right banks provided in the high pressure delivery pipe 112, and an intake passage injection injector 120. A low pressure delivery pipe 122 provided for each of the left and right banks for supplying fuel, and the low pressure delivery pipe 12 And a left and right banks intake manifold injectors 120 for each of the four provided.

  The discharge port of the fuel tank feed pump 100 is connected to a low-pressure supply pipe 400, and the low-pressure supply pipe 400 branches into a first low-pressure delivery communication pipe 410 and a pump supply pipe 420. The first low-pressure delivery communication pipe 410 becomes a second low-pressure delivery communication pipe 430 on the downstream side of the branch point with the low-pressure delivery pipe 122 of one bank of the V-shaped bank, and the low-pressure delivery pipe 122 of the other bank. It is connected to the.

  The pump supply pipe 420 is connected to the inlets of the first high-pressure fuel pump 200 and the second high-pressure fuel pump 300, respectively. A first pulsation damper 220 is provided in front of the entrance of the first high-pressure fuel pump 200, and a second pulsation damper 320 is provided in front of the entrance of the second high-pressure fuel pump 300, respectively. The fuel pulsation is reduced.

  The discharge port of the first high-pressure fuel pump 200 is connected to the first high-pressure delivery communication pipe 500, and the first high-pressure delivery communication pipe 500 is connected to the high-pressure delivery pipe 112 of one bank of the V-shaped bank. . The discharge port of the second high-pressure fuel pump 300 is connected to the second high-pressure delivery communication pipe 510, and the second high-pressure delivery communication pipe 510 is connected to the high-pressure delivery pipe 112 of the other bank of the V-shaped bank. The The high-pressure delivery pipe 112 of one bank of the V-type bank and the high-pressure delivery pipe 112 of the other bank are connected by a high-pressure communication pipe 520.

  A relief valve 114 provided in the high-pressure delivery pipe 112 is connected to the high-pressure fuel pump return pipe 600 via the high-pressure delivery return pipe 610. Return ports of the high-pressure fuel pump 200 and the high-pressure fuel pump 300 are connected to a high-pressure fuel pump return pipe 600. The high-pressure fuel pump return pipe 600 is connected to the return pipe 620 and the return pipe 630, and is connected to the fuel tank.

  FIG. 2 shows an enlarged view of the vicinity of the first high-pressure fuel pump 200 of FIG. The same applies to the second high-pressure fuel pump 300, but the cam phase is different and the discharge timing phase is shifted to suppress the occurrence of pulsation. The characteristics of the first high-pressure fuel pump 200 and the second high-pressure fuel pump 300 may be the same or different. In the following description, the discharge capacity of the first high-pressure fuel pump 200 and the discharge capacity of the second high-pressure fuel pump 300 may be the same or different in terms of specifications.

The high-pressure fuel pump 200 is driven by a cam 210 and slides up and down.
06, an electromagnetic spill valve 202, and a check valve 204 with a leak function are main components.

  When the pump plunger 206 is moved downward by the cam 210 and the electromagnetic spill valve 202 is open, fuel is introduced (sucked), and the pump plunger 206 is moved upward by the cam 210. When the electromagnetic spill valve 202 is closed, the timing for closing the electromagnetic spill valve 202 is changed to control the amount of fuel discharged from the high-pressure fuel pump 200. The earlier the timing for closing the electromagnetic spill valve 202 during the pressurization stroke in which the pump plunger 206 is moving upward, the more fuel is discharged, and the slower the fuel is discharged, the slower. The driving duty of the electromagnetic spill valve 202 when discharging the most is 100%, and the driving duty of the electromagnetic spill valve 202 when discharging the least is 0%. When the drive duty of the electromagnetic spill valve 202 is 0%, the electromagnetic spill valve 202 remains open without closing, and as long as the first cam 210 is rotating (as long as the engine is rotating). ) The pump plunger 206 slides in the vertical direction, but the fuel is not pressurized because the electromagnetic spill valve 202 does not close.

  The pressurized fuel is pushed open to the high pressure delivery pipe 112 via the first high pressure delivery communication pipe 500 by pushing open the check valve 204 with a leak function (set pressure of about 60 kPa). At this time, the fuel pressure is feedback controlled by a fuel pressure sensor provided in the high pressure delivery pipe 112. Further, as described above, the high pressure delivery pipe 112 of one bank of the V type and the high pressure delivery pipe 112 of the other bank are communicated by the high pressure communication pipe 520.

  The check valve 204 with a leak function is a normal check valve 204 provided with pores, and the pores are always open. Therefore, when the fuel pressure on the first high-pressure fuel pump 200 (pump plunger 206) side becomes lower than the fuel pressure in the first high-pressure delivery communication pipe 500 (for example, the electromagnetic spill valve 202 remains open, The engine is stopped and the cam 210 is stopped), and the high-pressure fuel in the first high-pressure delivery communication pipe 500 returns to the high-pressure fuel pump 200 through the pores, and the inside of the high-pressure delivery communication pipe 500 and the high-pressure delivery pipe 112. The fuel pressure drops. Thereby, for example, when the engine is stopped, the fuel in the high-pressure delivery pipe 112 is not at a high pressure, and fuel leakage from the in-cylinder injector 110 can be avoided.

  The engine ECU drives and controls the in-cylinder injector 110 based on the final fuel injection amount, and controls the amount of fuel injected from the in-cylinder injector 110. Since the amount of fuel (fuel injection amount) injected from the in-cylinder injector 110 is determined by the fuel pressure (fuel pressure) in the high-pressure delivery pipe 112 and the fuel injection time, in order to make the fuel injection amount appropriate. It is necessary to maintain the fuel pressure at an appropriate value. Therefore, the engine ECU appropriately controls the fuel pressure P by feedback-controlling the fuel discharge amount of the high-pressure fuel pump 200 so that the fuel pressure obtained based on the detection signal from the fuel pressure sensor approaches the target fuel pressure set according to the engine operating state. Keep the value. The fuel discharge amount of the high-pressure fuel pump 200 is feedback controlled by adjusting the closing period (valve closing start time) of the electromagnetic spill valve based on a duty ratio DT described later.

  Here, the duty ratio DT that is a control amount for controlling the fuel discharge amount of the high-pressure fuel pump 200 (the valve closing start timing of the electromagnetic spill valve 202) will be described. The duty ratio DT is a value that varies between 0% and 100%, and is a value related to the cam angle of the cam 210 corresponding to the valve closing period of the electromagnetic spill valve 202. That is, regarding this cam angle, the cam angle (maximum cam angle) corresponding to the maximum valve closing period of the electromagnetic spill valve 202 is “θ (0)”, and the cam angle corresponding to the target value of the valve closing period (target cam) Assuming that (angle) is “θ”, the duty ratio DT indicates the ratio of the target cam angle θ to the maximum cam angle θ (0). Accordingly, the duty ratio DT is set to a value closer to 100% as the valve closing period (the valve closing start timing) of the target electromagnetic spill valve 202 approaches the maximum valve closing period, and the target valve closing period is “0”. As the value approaches, the value approaches 0%.

  As the duty ratio DT approaches 100%, the closing timing of the electromagnetic spill valve 202 adjusted based on the duty ratio DT is advanced, and the closing period of the electromagnetic spill valve 202 becomes longer. As a result, the fuel discharge amount of the high-pressure fuel pump 200 increases and the fuel pressure P increases. Further, as the duty ratio DT approaches 0%, the closing timing of the electromagnetic spill valve 202 adjusted based on the duty ratio DT is delayed, and the closing period of the electromagnetic spill valve 202 is shortened. As a result, the fuel discharge amount of the high-pressure fuel pump 200 decreases and the fuel pressure P decreases.

  With reference to FIG. 3, a control structure of a program executed by an engine ECU that is a control device according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, the engine ECU detects the fuel pressure P of the high-pressure fuel based on a signal from a fuel pressure sensor provided in the high-pressure delivery pipe 112.

  In S110, the engine ECU determines whether or not the port injection ratio is 100%, that is, whether or not the entire fuel amount is injected by the intake manifold injector 120. This determination is made on the basis of a map that represents an injection ratio described later. If the DI ratio (r) in the map described later is 0, it is determined that the port injection ratio is 100%. If the port injection ratio is 100% (YES in S110), the process proceeds to S120. If not (NO in S110), the process proceeds to S200.

  In S120, engine ECU determines whether the target fuel pressure is higher than detected fuel pressure P or not. In this case, fuel is injected only from the intake manifold injector 120 so that the fuel pressure in the high-pressure delivery pipe 112 becomes the target fuel pressure in preparation for a command to inject fuel from the in-cylinder injector 110 thereafter. It is controlled. If the target fuel pressure is higher than detected fuel pressure P (YES in S120), the process proceeds to S130. That is, the fuel pressure in the high-pressure delivery pipe 112 is not sufficiently increased and is not maintained above the target fuel pressure. Otherwise (NO in S120), this process ends. That is, the fuel pressure P in the high-pressure delivery pipe 112 is sufficiently increased and maintained above the target fuel pressure.

  In S130, engine ECU determines whether or not high-pressure fuel pumps 200 and 300 are being driven. This determination is made based on, for example, a command value (duty) from the engine ECU to the high-pressure fuel pump. If high-pressure fuel pumps 200 and 300 are being driven (YES in S130), the process proceeds to S140. Otherwise (NO at S130), this process ends. That is, when the high-pressure fuel pumps 200 and 300 are not being driven, the failure of the high-pressure fuel system cannot be accurately determined.

  In S140, engine ECU determines whether or not detected fuel pressure P is lower than a predetermined lower limit threshold value. This lower threshold is a fuel pressure corresponding to a case where a failure has occurred in the high-pressure fuel system. That is, it is determined that an abnormality has occurred in the high-pressure fuel system when the detected fuel pressure P is lower than the lower threshold value even though the high-pressure fuel pumps 200 and 300 are driven. If detected fuel pressure P is lower than a predetermined lower threshold (YES in S140), the process proceeds to S150. Otherwise (NO in S140), this process ends.

  In S150, the engine ECU determines that the high-pressure fuel system is failing on the fuel pressure lowering side. For example, there is a case where a leak occurs in the high-pressure fuel system and the fuel pressure of the high-pressure delivery pipe 112 does not rise above the lower limit threshold value. Thereafter, this process ends.

  In S200, engine ECU determines whether or not detected fuel pressure P is higher than a predetermined upper limit threshold value. This upper threshold is a fuel pressure corresponding to a case where a failure occurs in the high-pressure fuel system. That is, if the detected fuel pressure P is higher than the upper limit threshold value, it is determined that an abnormality has occurred in the high-pressure fuel system. If detected fuel pressure P is higher than a predetermined upper limit threshold value (YES in S200), the process proceeds to S210. If not (NO in S200), the process proceeds to S140.

  In S210, the engine ECU determines that the high-pressure fuel system has failed on the fuel pressure increase side.

  The operation of the high-pressure fuel piping system controlled by the engine ECU, which is the control device according to the present embodiment, based on the above-described structure and flowchart will be described.

<When the port injection ratio is 100%>
The fuel pressure P of the high-pressure fuel system is detected by the fuel pressure sensor provided in the high-pressure delivery pipe 112 (S100).

  Based on an injection division map of in-cylinder injector 110 and intake manifold injector 120, which will be described later, this is a case where fuel is injected only from intake manifold injector 120 (YES in S110), If the detected fuel pressure P is equal to or higher than the target fuel pressure (NO in S120) or the detected fuel pressure P is lower than the target fuel pressure (YES in S120), but the high-pressure fuel pumps 200, 300 are not in operation ( NO in S130), the determination of fail of the high-pressure fuel system on the fuel pressure lowering side is not performed, and the process is terminated.

  When detected fuel pressure P is lower than the target fuel pressure (YES in S120) and high-pressure fuel pumps 200 and 300 are in operation (YES in S130), detected fuel pressure P is lower than the lower threshold. The fail judgment of the high-pressure fuel system on the fuel pressure lowering side is performed depending on whether it is low or not. At this time, if detected fuel pressure P is lower than the lower limit threshold value (YES in S140), it is determined that the high-pressure fuel system is failing on the fuel pressure lowering side (S150).

  Thus, when fuel is injected only from the intake manifold injector 120, the high-pressure fuel pumps 200 and 300 are driven in preparation for the start of fuel injection from the in-cylinder injector 110 thereafter. It is necessary to increase the fuel pressure in the high-pressure delivery pipe 112 to the target fuel pressure and maintain the fuel pressure. At this time, if the fuel pressure in the high pressure delivery pipe 112 is not at least equal to or lower than the lower limit threshold value, it can be determined that the high pressure fuel system has failed on the fuel pressure lowering side.

  On the other hand, fail judgment of the high-pressure fuel system on the fuel pressure increase side is not performed for the following reason. When fuel is injected only from the intake manifold injector 120, it is necessary to maintain the fuel at a high pressure in preparation for the start of fuel injection from the in-cylinder injector 110 thereafter. However, fuel is not injected from the in-cylinder injector 110, and the fuel in the high-pressure delivery pipe 112 tends to be heated by receiving heat from the engine. For this reason, although the high-pressure fuel system is operating normally, the fuel in the high-pressure delivery pipe 112 may become high temperature and high pressure. As a result, the fuel pressure in the high-pressure delivery pipe 112 may increase. May exceed the upper threshold. Therefore, when fuel is injected only from the intake manifold injector 120, it is possible to accurately determine the abnormality of the high-pressure fuel system without performing the fail determination of the high-pressure fuel system on the fuel pressure increase side. .

<When the port injection ratio is not 100%>
Based on an injection map of in-cylinder injector 110 and intake passage injector 120, which will be described later, fuel is shared and injected between in-cylinder injector 110 and intake passage injector 120 (NO in S110), fail determination of the high-pressure fuel system on the fuel pressure increase side and fail determination of the high-pressure fuel system on the fuel pressure decrease side are performed.

  That is, the fail judgment (S200, S210) of the high-pressure fuel system on the fuel pressure increase side based on whether or not the detected fuel pressure P is higher than the upper limit threshold, and the detected fuel pressure P is lower than the lower limit threshold Whether or not the high pressure fuel system fails on the fuel pressure lowering side is determined (S140, S150).

  At this time, if detected fuel pressure P is higher than the upper limit threshold value (YES in S200), it is determined that the high-pressure fuel system is failing on the fuel pressure increasing side (S210), and detected fuel pressure P is lower limit. If it is lower than the threshold value (YES in S140), it is determined that the high-pressure fuel system is failing on the fuel pressure lowering side (S150).

  As described above, when fuel is divided and injected by the in-cylinder injector 110 and the intake manifold injector 120, the fuel in the high-pressure delivery pipe 112 receives heat from the engine. Since the fuel is injected from the injector 110 for injection, the fuel in the fuel tank is consumed and the fuel in the high-pressure delivery pipe 112 does not tend to become high temperature. Therefore, the abnormality of the high-pressure fuel system can be accurately determined even if the failure determination of the high-pressure fuel system on the fuel pressure increase side and the failure determination of the high-pressure fuel system on the fuel pressure decrease side are performed.

  As described above, according to the engine ECU that is the control device according to the present embodiment, even when the fuel injection from the in-cylinder injector is stopped, the abnormality of the high-pressure fuel system is accurately determined. can do.

<Modification>
Hereinafter, modifications of the present embodiment will be described. In this modification, the engine ECU executes a program represented by the flowchart shown in FIG. 4, which is partly different from that in FIG. 3. The rest is the same as the above-described embodiment (FIGS. 1 and 2). Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 4, a control structure of a program executed by an engine ECU which is a control device according to this modification will be described. 4 is different from the flowchart shown in FIG. 3 in that the process of S300 is added. The other processes are the same. Therefore, detailed description thereof will not be repeated.

  In S300, the engine ECU executes a fuel pressure maintaining process for the high-pressure fuel system. At this time, the engine ECU transmits a control signal to the relief valve so as to close the relief valve 114 (in this modification, the relief valve 114 is an electromagnetic relief valve whose opening and closing can be controlled by the engine ECU). Further, the engine ECU monitors the elapsed time after the high-pressure fuel pumps 200 and 300 stop operating, or monitors the fuel pressure P in the high-pressure delivery pipe 112, so that the elapsed time is a predetermined time. If the fuel pressure P in the high-pressure delivery pipe 112 falls below a predetermined fuel pressure, the high-pressure fuel pumps 200 and 300 are operated.

  In this case, when the port injection ratio is 100% (YES in S110) and fuel pressure P in high pressure delivery pipe 112 is sufficiently increased and maintained above the target fuel pressure (NO in S120). (In such a case, it is not necessary to increase the fuel pressure in the high-pressure delivery pipe 112, so the fuel-pressure high-pressure fuel pumps 200, 300 are not driven) or the high-pressure fuel pumps 200, 300 are not being driven (S130). NO), the fuel pressure in the high-pressure delivery pipe 112 is maintained at a desired fuel pressure in preparation for a command to inject fuel from the in-cylinder injector 110 (S300). At this time, even if the relief valve 114 is closed and the fuel is not pumped from the high pressure fuel pumps 200 and 300 to the high pressure delivery pipe 112, the relief valve 114 is closed, so that the fuel pressure in the high pressure delivery pipe 112 can be set to a desired value. The fuel pressure can be maintained.

  When the high pressure fuel pumps 200 and 300 are not driven after a predetermined time has elapsed or when the fuel pressure P in the high pressure delivery pipe 112 becomes equal to or lower than the predetermined fuel pressure, Even if 300 is driven and the port injection ratio is 100%, it is possible to maintain the desired fuel pressure in preparation for the command to inject fuel from in-cylinder injector 110.

<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. 5 and 6, the injection ratio of in-cylinder injector 110 and intake manifold injector 120 (hereinafter referred to as DI ratio (r)), which is information corresponding to the operating state of the engine. Will be described. These maps are stored in the ROM of the engine ECU. FIG. 5 is an engine warm map, and FIG. 6 is an engine cold map.

  As shown in FIG. 5 and FIG. 6, these maps show the engine rotation speed on the horizontal axis, the load factor on the vertical axis, and the share ratio of the in-cylinder injector 110 as a DI ratio r as a percentage. Has been.

  As shown in FIGS. 5 and 6, the DI ratio r is set for each operation region determined by the engine speed and the load factor. “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 these two types of injectors with different characteristics depending on the engine speed and load factor, the engine is in a normal operating state (for example, when the catalyst is warming up when idling is in a non-normal operating state other than the normal operating state) In other words, only homogeneous combustion is performed.

  Further, as shown in FIG. 5 and FIG. 6, the DI share ratio r of the in-cylinder injector 110 and the intake manifold injector 120 is defined separately for the warm time map and the cold time map. did. When the engine temperature is different, the engine temperature is detected in advance by using the maps 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 the temperature threshold value, the warm time map shown in FIG. 5 is selected. Otherwise, the cold time map shown in FIG. 6 is selected. Based on the selected maps, the in-cylinder injector 110 and / or the intake manifold injector 120 are controlled based on the engine speed and the load factor.

  The engine speed and load factor set in FIGS. 5 and 6 will be described. In FIG. 5, 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. 6 is set to 2900-3100 rpm. That is, NE (1) <NE (3). In addition, NE (2) in FIG. 5 and KL (3) and KL (4) in FIG. 6 are also set as appropriate.

  When FIG. 5 and FIG. 6 are compared, NE (3) of the map for cold shown in FIG. 6 is higher than NE (1) of the map for warm shown in FIG. This indicates that the lower the engine temperature, the larger the control range of the intake manifold injector 120 is to a higher engine speed range. That is, since the engine is cold, 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.

  Comparing FIG. 5 and FIG. 6, in the region where the engine speed is NE (1) or higher in the warm map and in the region of NE (3) or higher in the cold map, “DI ratio r = 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 with the in-cylinder injector 110, the mixture is mixed even with the in-cylinder injector 110 alone because the engine speed and load are high 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. 5, only the in-cylinder injector 110 is used at a load factor KL (1) or less. This indicates that when the engine temperature is high, only the in-cylinder injector 110 is used in a predetermined low load region. This is because when the engine is warm, the engine is warm, 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 reason, the in-cylinder injector 110 is used as an area.

  Comparing FIG. 5 and FIG. 6, the region of “DI ratio r = 0%” exists only in the cold map of FIG. 6. This indicates that when the engine temperature 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 is cold, the engine load 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, the in-cylinder injector 110 is controlled so as to perform stratified combustion when the engine is warming up when the engine is idling (in a non-normal operation state). By performing 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 FIG. 7 and FIG. 8, a map representing an injection ratio of in-cylinder injector 110 and intake passage injector 120, which is information corresponding to the operating state of the engine, will be described. These maps are stored in the ROM of the engine ECU. FIG. 7 is an engine warm map, and FIG. 8 is an engine cold map.

  7 and 8 differ from FIGS. 5 and 6 in the following points. The engine speed 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 cross arrows are shown in FIGS. 7 and 8) 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 described with reference to FIGS. 5 to 8, the homogeneous combustion is performed by setting the fuel injection timing of the in-cylinder injector 110 as the intake stroke, and the stratified combustion is performed by the fuel injection of the in-cylinder injector 110. This can be realized by making the timing a 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. That is, 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 during catalyst warm-up. 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 such a viewpoint, it is preferable to use the above-described weak stratified combustion at the time of warming up the catalyst, but either stratified combustion or weak stratified combustion may be used.

  In the engine described with reference to FIGS. 5 to 8, the fuel injection timing by the in-cylinder injector 110 is preferably performed in the compression stroke for the following reason. However, the engine described above has a weak stratification in most basic areas (injection stroke injection is performed only when the catalyst is warmed up, and in-cylinder injection injector 110 is subjected to compression stroke injection. The timing of fuel injection by the in-cylinder injector 110 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 stroke, 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 stroke, the time from the fuel injection to the ignition timing is short, so that the air flow 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 engine temperature (that is, whether it is warm or cold), it is off-idle (when the idle switch is off and the accelerator pedal is depressed). 5 or 7 may be used (the in-cylinder injector 110 is used in the low load region regardless of the cold temperature).

  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 an overall schematic diagram of a fuel supply system for a gasoline engine controlled by a control device according to an embodiment of the present invention. It is the elements on larger scale of FIG. It is a flowchart which shows the control structure of the program performed by engine ECU. It is a flowchart which shows the control structure of the program performed by engine ECU which concerns on a modification. 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

  DESCRIPTION OF SYMBOLS 10 Fuel supply system, 100 Feed pump, 110 In-cylinder injector, 112 High pressure delivery pipe, 114 Relief valve, 120 Intake passage injector, 122 Low pressure delivery pipe, 200 1st high pressure fuel pump, 202 Electromagnetic spill valve, 204 Check valve with leak function, 206 Pump plunger, 210 First cam, 220 First pulsation damper, 300 Second high pressure fuel pump, 310 Second cam, 320 Second pulsation damper, 400 Low pressure Supply pipe, 410 first low pressure delivery communication pipe, 420 pump supply pipe, 430 second low pressure delivery communication pipe, 500 first high pressure delivery communication pipe, 510 second high pressure delivery communication pipe, 520 high pressure communication pipe 600, high pressure fuel pump return pipe, 610 high pressure delivery return pipe, 620, 630 return pipe.

Claims (6)

An abnormality detection device for a fuel system of an internal combustion engine, having at least two fuel systems, to which fuel is supplied by fuel injection means connected to each of the fuel systems, wherein no fuel is injected by the first fuel injection means Even in the case where the fuel is injected by the second fuel injection means other than the first fuel injection means, the fuel in the first fuel system for supplying the fuel to the first fuel injection means Is controlled to the desired pressure,
Detecting means for detecting the pressure of the fuel in the first fuel system;
In a state in which the fuel pressure in the first fuel system is controlled to be the desired pressure, the detected fuel pressure is compared with a predetermined threshold value to compare the first fuel system with the predetermined pressure. Determining means on the pressure increase side for determining whether or not an abnormal state in which the fuel pressure in one fuel system excessively increases;
An abnormality determination device for a fuel system of an internal combustion engine, including prohibition means for prohibiting determination by the determination means on the pressure increase side when fuel is not injected by the first fuel injection means. The first fuel injection means includes means for injecting high-pressure fuel supplied from the first fuel system into the cylinder,
The second fuel injection means includes means for injecting fuel supplied from the second fuel system into the intake passage,
The determination unit on the pressure increase side determines that the fuel pressure in the first fuel system is abnormally increased when the detected fuel pressure is higher than a predetermined threshold value. The abnormality determination device for a fuel system of an internal combustion engine according to claim 1, comprising means for:   The abnormality determination device compares the detected fuel pressure with a predetermined threshold value regardless of the injection mode of the fuel injection means, so that the fuel pressure in the first fuel system is excessive. The abnormality determination device for a fuel system of an internal combustion engine according to claim 1, further comprising determination means on the pressure drop side for determining whether or not an abnormal state that decreases rapidly. The first fuel injection means includes means for injecting high-pressure fuel supplied from the first fuel system into the cylinder,
The second fuel injection means includes means for injecting fuel supplied from the second fuel system into the intake passage,
The determination unit on the pressure decrease side determines that the fuel pressure in the first fuel system is excessively decreased when the detected fuel pressure is lower than a predetermined threshold value. An abnormality determination device for a fuel system of an internal combustion engine according to claim 3, comprising means for: The first fuel system includes a high-pressure pump that makes the fuel a high pressure,
The determination means on the pressure drop side is configured to detect the detected fuel when the detected fuel pressure is lower than a target pressure in the first fuel system and the high-pressure pump is driven. 5. The internal combustion engine of claim 4, further comprising means for determining that the fuel pressure in the first fuel system is abnormally low when the pressure of the fuel is lower than a predetermined threshold value. An abnormality determination device for an engine fuel system. The first fuel injection means is an in-cylinder injector,
The abnormality determination device for a fuel system of an internal combustion engine according to any one of claims 1 to 5, wherein the second fuel injection means is an injector for an intake passage.

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