JP4400513B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply device for an internal combustion engine, and more particularly to a fuel supply device for an internal combustion engine in which fuel discharged from a low pressure pump is further pressurized by a high pressure pump.

  In a direct injection engine that is directly injected into a cylinder, a high fuel pressure is required. Therefore, fuel discharged from a low pressure pump is further pressurized by a high pressure pump. In such an engine, a buffer member such as a pulsation damper is provided to suppress fuel pulsation between the low pressure pump and the high pressure pump.

  Japanese Patent Laying-Open No. 2003-176750 (Patent Document 1) discloses a diagnostic device for a pressure damper (pulsation damper). The diagnostic device described in Patent Document 1 is a low-pressure fuel metering system having a pre-transport pump (low-pressure pump) that transports fuel from a fuel container to a low-pressure region and a high-pressure pump that transports fuel from a low-pressure region to a high-pressure region. Diagnose the pressure damper located in the area. This diagnostic device detects and evaluates the pressure course in the low pressure region and uses the detected pressure course to diagnose the pressure damper.

According to the diagnostic device described in this publication, the pressure damper in the low pressure region of the fuel metering system can be monitored during the operation of the internal combustion engine by the on-board diagnostic function, so that the failed pressure damper can be diagnosed early.
JP 2003-176750 A

  An engine including a low pressure pump and a high pressure pump is designed so that the amount of fuel discharged from the low pressure pump satisfies the amount of fuel drawn into the high pressure pump. By the way, in order to further improve the fuel consumption, it is conceivable to reduce the discharge amount from the low-pressure pump and reduce the load in the low-pressure pump. However, Japanese Patent Application Laid-Open No. 2003-176750 does not describe any method for reducing the load in the low-pressure pump.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel supply device for an internal combustion engine that can improve fuel efficiency.

  A fuel supply device for an internal combustion engine according to a first aspect of the present invention is provided between a low pressure pump for supplying fuel from a fuel tank to fuel injection means, and between the low pressure pump and the fuel injection means, and further supplies the pressure of the supplied fuel. A high-pressure pump that is raised, and a buffer member that is provided between the low-pressure pump and the high-pressure pump and suppresses fuel pulsation by storing fuel in an oil chamber whose volume changes. The amount of fuel discharged by the low pressure pump is determined based on the amount of fuel sucked by the high pressure pump and the volume of the oil chamber.

  According to the first invention, since the buffer member functions as a pump by changing the volume of the oil chamber, taking into account this function, the amount of fuel discharged by the low-pressure pump is equal to the amount of fuel sucked by the high-pressure pump. It is determined based on the volume of the oil chamber. For example, the amount of fuel discharged by the low pressure pump is a fuel amount obtained by subtracting the amount of change in the volume of the oil chamber from the amount of fuel sucked by the high pressure pump. Thereby, the amount of fuel discharged from the low pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption. As a result, it is possible to provide a fuel supply device for an internal combustion engine that can improve fuel consumption.

  In the fuel supply device for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the amount of fuel discharged by the low pressure pump is obtained by subtracting the amount of change in the volume of the oil chamber from the amount of fuel sucked by the high pressure pump This is the amount of fuel consumed.

  According to the second invention, the amount of fuel discharged by the low pressure pump is a fuel amount obtained by subtracting the amount of change in the volume of the oil chamber from the amount of fuel sucked by the high pressure pump. Thereby, the amount of fuel discharged from the low pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption.

  A fuel supply device for an internal combustion engine according to a third aspect of the present invention is provided between a low pressure pump for supplying fuel from a fuel tank to fuel injection means, and between the low pressure pump and the fuel injection means, and further supplies the pressure of the supplied fuel. A high-pressure pump that is raised, and a buffer member that is provided between the low-pressure pump and the high-pressure pump and suppresses fuel pulsation by storing fuel in an oil chamber whose volume changes. The volume of the oil chamber is determined based on the amount of fuel sucked by the high pressure pump and the amount of fuel discharged from the low pressure pump.

  According to the third invention, since the buffer member functions as a pump by changing the volume of the oil chamber, the volume of the oil chamber is set to a high pressure so that the amount of fuel considering this function is sucked into the high pressure pump. It is determined based on the amount of fuel sucked by the pump and the amount of fuel discharged from the low pressure pump. For example, the amount of change in the volume of the oil chamber is the amount of fuel obtained by subtracting the amount of fuel discharged by the low-pressure pump from the amount of fuel sucked by the high-pressure pump. Thereby, a fuel amount larger than the fuel amount discharged from the low pressure pump can be supplied to the high pressure pump. That is, the amount of fuel discharged from the low-pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption. As a result, it is possible to provide a fuel supply device for an internal combustion engine that can improve fuel consumption.

  In the fuel supply device for an internal combustion engine according to the fourth aspect of the invention, in addition to the configuration of the third aspect, the amount of change in the volume of the oil chamber is obtained by subtracting the amount of fuel discharged by the low-pressure pump from the amount of fuel sucked by the high-pressure pump. This is the amount of fuel consumed.

  According to the fourth invention, for example, the change amount of the volume of the oil chamber is a fuel amount obtained by subtracting the fuel amount discharged from the low pressure pump from the fuel amount sucked by the high pressure pump. Thereby, a fuel amount larger than the fuel amount discharged from the low pressure pump can be supplied to the high pressure pump. That is, the amount of fuel discharged from the low-pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption.

  A fuel supply device for an internal combustion engine according to a fifth aspect of the present invention is provided between a low pressure pump that supplies fuel from a fuel tank to fuel injection means, and between the low pressure pump and the fuel injection means, and further supplies the pressure of the supplied fuel. A high-pressure pump that is raised, and a buffer member that is provided between the low-pressure pump and the high-pressure pump and suppresses fuel pulsation by storing fuel in an oil chamber whose volume changes. The amount of fuel sucked by the high pressure pump is determined based on the amount of fuel discharged from the low pressure pump and the volume of the oil chamber.

  According to the fifth invention, since the buffer member functions as a pump by changing the volume of the oil chamber, the amount of fuel sucked by the high-pressure pump is the same as the amount of fuel discharged from the low-pressure pump in consideration of this function. It is determined based on the volume of the oil chamber. For example, the amount of fuel sucked by the high-pressure pump is a fuel amount obtained by adding the amount of fuel discharged from the low-pressure pump and the amount of change in the volume of the oil chamber. Thereby, a fuel amount larger than the fuel amount discharged from the low pressure pump can be supplied to the high pressure pump. That is, the amount of fuel discharged from the low-pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption. As a result, it is possible to provide a fuel supply device for an internal combustion engine that can improve fuel consumption.

  In the fuel supply device for an internal combustion engine according to the sixth aspect of the invention, in addition to the configuration of the fifth aspect of the invention, the amount of fuel sucked by the high-pressure pump includes the amount of fuel discharged from the low-pressure pump and the amount of change in the volume of the oil chamber. The amount of fuel added.

  According to the sixth aspect of the invention, the amount of fuel sucked by the high pressure pump is a fuel amount obtained by adding the amount of fuel discharged from the low pressure pump and the amount of change in the volume of the oil chamber. Thereby, a fuel amount larger than the fuel amount discharged from the low pressure pump can be supplied to the high pressure pump. That is, the amount of fuel discharged from the low-pressure pump can be reduced by the amount that the buffer member functions as a pump. Therefore, it is possible to suppress the load on the low-pressure pump and ultimately improve the fuel consumption.

  In the fuel supply device for an internal combustion engine according to the seventh invention, in addition to the configuration of any one of the first to sixth inventions, the fuel injection means is a first fuel injection means for injecting fuel into the cylinder. The internal combustion engine further includes second fuel injection means for injecting fuel into the intake passage.

  According to the seventh invention, not only the internal combustion engine having only the first fuel injection means for injecting fuel into the cylinder, but also the first fuel injection means for injecting fuel into the cylinder and the intake passage In an internal combustion engine having a second fuel injection means for injecting fuel into the fuel, the amount of fuel discharged from the low-pressure pump is reduced by the amount that the buffer member functions as a pump to suppress the load on the low-pressure pump and improve fuel efficiency can do.

  In the fuel supply device for an internal combustion engine according to the eighth invention, in addition to the structure of the seventh invention, the first fuel injection means is an in-cylinder injector, and the second fuel injection means is an intake air It is an injector for channel injection.

  According to an eighth aspect of the present invention, in the internal combustion engine in which the in-cylinder injector that is the first fuel injection means and the intake passage injection injector that is the second fuel injection means are separately provided to share the injected fuel, The amount of fuel discharged from the pump can be reduced by the amount that the buffer member functions as a pump, so that the load on the low-pressure pump can be suppressed and fuel consumption can be improved.

  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 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 Note that the present invention is not limited to such an engine, and is applicable to other types of gasoline engines (V type 6 cylinders, inline 6 cylinders, inline 4 cylinders, etc.) and common rail diesel engines. Also good. Furthermore, the number of high-pressure fuel pumps is not limited to two, but may be one or more. Further, only one of in-cylinder injector 110 and intake passage injector 120 may be provided.

  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 discharge pressure of a low pressure (set pressure of the pressure regulator 102) 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 having a discharge phase different from that of the first high pressure fuel pump 200 and the first cam 210, and the in-cylinder injector 110. Fuel is supplied to the high-pressure delivery pipe 112 provided for each of the left and right banks for supply, the in-cylinder injectors 110 for each of the left and right banks provided for the high-pressure delivery pipe 112, and the intake manifold injector 120. The low pressure delivery pipe 122 provided for each of the left and right banks for supplying the And a intake manifold injectors 120 for each of the four left and right banks. Note that the discharge phase of the first cam 210 and the discharge phase of the second cam 310 may not be different.

  A pressure regulator 102 is provided at the discharge port of the feed pump 100 of the fuel tank. The pressure regulator 102 is connected to an engine ECU (Electronic Control Unit), and the set pressure can be changed by the engine ECU. The set pressure is, for example, about 300 kPa to 700 kPa. When the pressure of the fuel discharged from the feed pump 100 becomes equal to or higher than the pressure set by the pressure regulator 102, only the fuel corresponding to the excess pressure is returned to the fuel tank as relief fuel. Since the pressure regulator 102 is provided in the fuel tank as a relief fuel, the fuel heated after passing through the engine room will not return to the fuel tank, so the generation of evaporation gas in the fuel tank is suppressed. Yes. The pressure regulator 102 may be provided at the end of the low pressure delivery pipe instead of being provided in the fuel tank in this way.

  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 are the same in specification, but the control characteristics differ depending on the individual differences.

  The high-pressure fuel pump 200 includes a pump plunger 206 that is driven by a cam 210 and slides up and down, an electromagnetic spill valve 202, and a check valve 204 with a leak function as 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. Note that a check valve 204 having no leak function may be used.

  The first pulsation damper 220 will be described in detail with reference to FIG. Since second pulsation damper 320 is the same as first pulsation damper 220, detailed description thereof will not be repeated here.

  The first pulsation damper 220 includes a spring 222 and a diaphragm 224. The diaphragm 224 is biased downward in FIG. 3 by the spring 222. The diaphragm 224 moves up and down by the fuel pressure, fuel is stored in an oil chamber formed by the diaphragm 224, and fuel is discharged from the oil chamber, thereby suppressing fuel pulsation.

  When the fuel pressure increases, the diaphragm 224 moves upward in FIG. When the fuel pressure is lowered from this state, the diaphragm 224 moves downward in FIG. At this time, at most, the same amount of fuel as the movable part volume obtained from the product of the lift amount L of the diaphragm 224 and the pressure receiving diameter D (pressure receiving area S) is discharged from the first pulsation damper 220. That is, the first pulsation damper 220 can function as a pump.

  With reference to FIG. 4, the amount of fuel discharged from the first high-pressure fuel pump 200 and the amount of fuel sucked will be described. The second high-pressure fuel pump 300 is the same as the first high-pressure fuel pump 200, and therefore detailed description thereof will not be repeated here.

  In the state where the first high-pressure fuel pump 200 sucks fuel, the sucked fuel is pumped from the pump plunger 206 at the lowest end until the electromagnetic spill valve 202 is closed until the electromagnetic spill valve 202 is closed. And is temporarily stored in the pulsation damper 220.

  Thereafter, when the electromagnetic spill valve 202 is closed, the fuel is discharged from the first high-pressure fuel pump 200 to the high-pressure delivery communication pipe 500 side as the pump plunger 206 is raised until the pump plunger 206 is positioned at the uppermost end. Is done.

  Thereafter, when the pump plunger 206 starts to move downward, the electromagnetic spill valve 202 is opened, and the fuel is sucked into the first high-pressure fuel pump 200. At this time, the diaphragm 224 of the pulsation damper 220 moves downward, and the fuel once stored in the pulsation damper 220 is discharged. Therefore, the first high-pressure fuel pump 200 sucks the fuel discharged from the feed pump 100 and the pulsation damper 220.

  Considering the function of the pulsation damper as a pump, the amount of fuel discharged by the feed pump 100, the amount of fuel sucked by the high-pressure fuel pump, and the volume of the movable part of the pulsation damper (pulsation damper) Is determined).

  That is, the high-pressure fuel pump, the feed pump 100, and the pulsation damper are set so as to satisfy (fuel amount sucked by the high-pressure fuel pump) = (fuel amount discharged by the feed pump 100) + (movable part volume of the pulsation damper). Specifications (intake fuel amount, discharge fuel amount, movable part volume, etc.) are set.

  In the present embodiment, (the sum of the fuel amount sucked by the first high-pressure fuel pump 200 and the fuel amount sucked by the second high-pressure pump 300) = (the fuel amount discharged by the feed pump 100) + (the first The specifications of each high-pressure fuel pump, feed pump 100 and each pulsation damper are set so as to satisfy the sum of the movable part volume of one pulsation damper 220 and the movable part volume of the second pulsation damper 320). The

  Thereby, more fuel than the amount of fuel discharged by the feed pump 100 can be supplied to the high-pressure fuel pump. That is, the amount of fuel discharged from the feed pump 100 can be reduced by the amount of the movable part of the pulsation damper. Therefore, it is possible to suppress the driving load of the feed pump 100 and ultimately improve the fuel consumption.

  It is desirable to set the specifications of the feed pump 100 so that the amount of fuel discharged from the feed pump 100 becomes the maximum required fuel amount (maximum consumed fuel amount) of the engine. This suppresses the shortage of fuel supplied from the fuel tank to the engine in all operating conditions, and prevents the fuel supplied to the engine from becoming excessive in operating conditions that require the maximum required fuel amount. This is because it can be suppressed.

  At this time, if the specifications of at least one of the three parts are determined according to the specifications of the other parts, the parts are shared regardless of the engine type. be able to.

  For example, when the specifications of the feed pump 100 are set so that the amount of fuel discharged from the feed pump 100 becomes the maximum required fuel amount of the engine, the specifications of the pulsation damper are set according to the specifications of the high-pressure fuel pump. If set, the high-pressure fuel pump can be shared regardless of the engine type.

  The feed pump 100 and the pulsation damper may be shared regardless of the engine type. Further, any two of the three parts may be shared regardless of the engine type.

  Furthermore, the specifications of the feed pump 100 may be determined from the specifications of the high-pressure fuel pump and the specifications of the pulsation damper. Furthermore, the specifications of the high pressure fuel pump may be determined from the specifications of the pulsation damper and the specifications of the feed pump 100.

  As described above, according to the fuel supply system of the engine according to the present embodiment, (amount of fuel sucked by the high-pressure fuel pump) = (amount of fuel discharged by the feed pump) + (movable part volume of the pulsation damper) The specifications of the high-pressure fuel pump, feed pump, and pulsation damper are set so as to satisfy the above. Thereby, the amount of fuel discharged from the feed pump can be reduced by the amount that the pulsation damper functions as a pump. Therefore, it is possible to suppress the load on the feed pump and ultimately improve fuel efficiency.

<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 an engine fuel supply system according to an embodiment of the present invention. It is the elements on larger scale of FIG. It is a figure which shows the pulsation damper of FIG. It is a figure which shows the relationship between the fuel discharged from a high pressure fuel pump, and the fuel inhaled. 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, 102 Pressure regulator, 110 In-cylinder injector, 112 High pressure delivery pipe, 114 Relief valve, 120 Intake passage injection injector, 122 Low pressure delivery pipe, 200 1st high pressure fuel pump, 202 Solenoid 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 pipe Re-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 (8)

A fuel supply device for an internal combustion engine,
A low-pressure pump for supplying fuel from the fuel tank to the fuel injection means;
A high-pressure pump that is provided between the low-pressure pump and the fuel injection means and further increases the pressure of the supplied fuel;
A buffer member provided between the low-pressure pump and the high-pressure pump and suppressing fuel pulsation by storing fuel in an oil chamber whose volume changes;
The fuel supply device for an internal combustion engine, wherein the amount of fuel discharged from the low-pressure pump is determined based on a fuel amount sucked by the high-pressure pump and a maximum value of a change amount of the volume of the oil chamber. 2. The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel amount discharged from the low pressure pump is a fuel amount obtained by subtracting a maximum value of a change amount of the volume of the oil chamber from a fuel amount sucked by the high pressure pump. . A fuel supply device for an internal combustion engine,
A low-pressure pump for supplying fuel from the fuel tank to the fuel injection means;
A high-pressure pump that is provided between the low-pressure pump and the fuel injection means and further increases the pressure of the supplied fuel;
A buffer member provided between the low-pressure pump and the high-pressure pump and suppressing fuel pulsation by storing fuel in an oil chamber whose volume changes;
The maximum value of the change amount of the volume of the oil chamber is determined based on a fuel amount sucked by the high pressure pump and a fuel amount discharged from the low pressure pump. 4. The fuel supply device for an internal combustion engine according to claim 3, wherein the maximum value of the change amount of the volume of the oil chamber is a fuel amount obtained by subtracting a fuel amount discharged from the low pressure pump from a fuel amount sucked by the high pressure pump. . A fuel supply device for an internal combustion engine,
A low-pressure pump for supplying fuel from the fuel tank to the fuel injection means;
A high-pressure pump that is provided between the low-pressure pump and the fuel injection means and further increases the pressure of the supplied fuel;
A buffer member provided between the low-pressure pump and the high-pressure pump, for suppressing fuel pulsation by storing fuel in an oil chamber whose volume changes,
The fuel supply device for an internal combustion engine, wherein the amount of fuel sucked by the high-pressure pump is determined based on the amount of fuel discharged from the low-pressure pump and a maximum value of a change amount of the volume of the oil chamber. The fuel supply of the internal combustion engine according to claim 5, wherein the fuel amount sucked by the high-pressure pump is a fuel amount obtained by adding a fuel amount discharged from the low-pressure pump and a maximum value of a change amount of the volume of the oil chamber. apparatus. The fuel injection means is a first fuel injection means for injecting fuel into a cylinder,
The fuel supply device for an internal combustion engine according to any one of claims 1 to 6, wherein the internal combustion engine further includes a second fuel injection means for injecting fuel into the intake passage. The first fuel injection means is an in-cylinder injector,
The fuel supply apparatus for an internal combustion engine according to claim 7, wherein the second fuel injection means is an intake passage injection injector.

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