JP2010133265A - Fuel supply system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply system for an internal combustion engine, certainly increasing high fuel pressure to fuel pressure required for cylinder injection in initial starting in a dual injection internal combustion engine. <P>SOLUTION: A solenoid spill valve 40 has a valve element 41 which is opened according to differential pressure between fuel pressure from a feed pump 25 and fuel pressure in a pressurization chamber 35a with respect to the suction operation of a pressurization pump 35 and is closed according to differential pressure between fuel pressure from the feed pump 25 and fuel pressure in the pressurization chamber 35a with respect to the delivery operation of the pressurization chamber 35. An engine control computer 50 as an air bleeding control means periodically opens the solenoid spill valve 40 to fill the inside of the pressurization chamber 35a with fuel having a first fuel pressure level fed from the feed pump 25 when a condition that is not more than a specific pressure value which does not reach a second fuel pressure level injecting discharge pressure from the pressurization pump 35 during initial starting of the engine 10 is continued beyond predetermined pressure determination time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel supply device for an internal combustion engine, and more particularly to a dual injection type that uses both a fuel injection valve for port injection and a fuel injection valve for in-cylinder injection to release air from fuel in a high-pressure fuel passage. The present invention relates to a fuel supply device for a possible internal combustion engine.

  Recently, in an internal combustion engine for a vehicle such as an automobile, high pressure fuel is directly applied to a combustion chamber by a fuel injection valve for in-cylinder injection in the case of a spark ignition type in response to a high demand for fuel consumption and exhaust purification performance. A lean combustion system that makes the air-fuel mixture rich enough to ensure ignition only in the vicinity of the spark plug by injecting the engine, or an idling stop technology that stops the engine when the vehicle is stopped, is adopted . For this reason, there has been proposed a technique for highly suppressing air from being mixed into the fuel or generating fuel vapor.

  As a fuel supply device for this type of internal combustion engine, for example, an additional thread notch for venting air is formed in a female threaded portion to which an overflow valve is screwed in a housing of a transfer unit that supplies fuel for the internal combustion engine. Is known (for example, see Patent Document 1).

  In a common rail internal combustion engine, if it is determined that the rail pressure does not reach the predetermined pressure during cranking, the metering valve that adjusts the amount of fuel supplied from the low-pressure feed pump to the pressurization pump is fully closed. For example, there is known a method in which air mixed in the low-pressure fuel system upstream is returned to the tank side together with fuel to remove the mixed air (see, for example, Patent Document 2).

Further, there is known a method in which air is vented by opening an on-off valve on a leakage passage connected to a pressure control chamber in an injector when air is mixed into the fuel (see, for example, Patent Document 3).
JP 2005-537426 A JP 2004-144037 A JP 2001-263191 A

  However, the fuel supply device for the conventional internal combustion engine as described above, in particular, the fuel supply device equipped in the dual injection type internal combustion engine that uses both the fuel injection valve for port injection and the fuel injection valve for in-cylinder injection. In this case, even if the pressurization pump is operated during the port injection immediately after starting, air is mixed into the fuel in the pressurization pump or fuel vapor is generated. May not be sufficiently sucked into the high-pressure fuel pump, and the fuel pressure in the high-pressure fuel passage may not increase to the fuel pressure required for in-cylinder injection within a certain time.

  Therefore, for example, in a vehicle assembly plant, an MIL (Malfunction Indicator Lamp), which is an abnormality warning lamp, is turned on due to an abnormality in the fuel pressure, and the vehicle that has reached the inspection process after assembly is taken out of the manufacturing / inspection line. The troublesome work of turning off the MIL is required, which causes a problem that the production efficiency of the vehicle decreases.

  The present invention has been made in order to solve the above-described conventional problems. In a dual injection internal combustion engine, the fuel pressure required for in-cylinder injection of the fuel pressure in the high pressure fuel passage within a predetermined time at the initial start is provided. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can be reliably increased.

  In order to achieve the above object, a fuel supply apparatus for an internal combustion engine according to the present invention injects fuel into a port injection fuel injector for injecting fuel into an intake port of the internal combustion engine, and injects the fuel into a cylinder of the internal combustion engine. A fuel injection valve for in-cylinder injection; and a fuel supply means for supplying the fuel to both fuel injection valves. The fuel supply means supplies the fuel to the fuel injection valve for port injection as a first fuel. A feed pump that feeds at a pressure level, and a second fuel that has a pressurizing chamber that introduces fuel fed from the feed pump and that has a higher pressure than the first fuel pressure level. In a fuel supply apparatus for an internal combustion engine, comprising: a pressurizing pump that pressurizes to a pressure level and discharges to the fuel injection valve side; and an electromagnetic spill valve that opens in response to an input signal and leaks fuel in the pressurizing chamber The electromagnetic spill valve is In response to the suction operation of the pressurizing pump, the valve opens according to the differential pressure between the fuel pressure fed from the feed pump and the fuel pressure in the pressurizing chamber, and to the discharge operation of the pressurizing pump. And a valve body that performs a valve closing operation in accordance with a differential pressure between the fuel pressure fed from the feed pump and the fuel pressure in the pressurizing chamber. When the state where the discharge pressure of the fuel discharged from the fuel is not more than a specific pressure value that does not reach the second fuel pressure level continues beyond a preset pressure determination time, the electromagnetic spill valve is periodically An air vent control means is provided that opens the valve and fills the pressurized chamber with fuel of the first fuel pressure level fed from the feed pump.

  With this configuration, when the state in which the discharge pressure from the pressurizing pump becomes a specific pressure value or less during the initial start of the internal combustion engine continues beyond the pressure determination time, the electromagnetic spill valve is periodically opened to increase the pressure. The chamber is filled with fuel at a first fuel pressure level from a feed pump. Therefore, at the time of initial start-up such as inspection after assembly, the fuel is sufficiently supplied into the pressurizing chamber and flows out from the pressurizing chamber to the fuel injection valve side, so that the pressurization pump can be vented. . Moreover, it is only necessary to add a program for achieving the function of the air bleeding control means to the existing fuel injection system.

  The air vent control means periodically opens the in-cylinder injection fuel injection valve in synchronization with the opening of the electromagnetic spill valve when the electromagnetic spill valve is periodically opened. Is preferred. Further, when the air bleeding control means is at the time of starting the internal combustion engine and within the pressure determination time, the fuel fed by the feed pump is transferred from the fuel injection valve for port injection to the intake port. When the state in which the discharge pressure of the fuel discharged from the pressurizing pump remains below the specific pressure value continues beyond the pressure determination time, the port injection fuel injection valve is closed. It is better to let it be valved. Further, a valve is opened in a high-pressure fuel passage between the fuel injection valve for in-cylinder injection and the pressurizing pump when a discharge pressure of fuel discharged from the pressurization pump exceeds the specific pressure value. It is desirable to provide a check valve that allows the fuel to be supplied to the fuel injection valve for in-cylinder injection.

  According to the present invention, when the state in which the discharge pressure from the pressurizing pump becomes a specific pressure value or less during the initial start of the internal combustion engine continues beyond the pressure determination time, the electromagnetic spill valve is periodically opened. Since the fuel at the first fuel pressure level from the feed pump is filled in the pressurizing chamber, the fuel is sufficiently supplied to the pressurizing chamber and added at the initial start-up such as the inspection after assembly. The pressure pump can be discharged from the pressure chamber to the fuel injection valve side, and the pressurization pump can be surely vented. In a dual injection internal combustion engine, the fuel pressure in the high pressure fuel passage is changed to in-cylinder injection within a certain time immediately after the initial start. It is possible to provide a fuel supply device for an internal combustion engine that can reliably increase the required fuel pressure.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a fuel supply device for an internal combustion engine according to one embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the fuel supply device according to one embodiment.

  First, the configuration will be described.

  As shown in FIG. 1, the fuel supply device for an internal combustion engine of the present embodiment is an internal combustion engine in which fuel is directly injected into a combustion chamber in each cylinder, for example, a direct injection spark ignition type internal combustion engine. The V-type 6-cylinder engine 10 is equipped.

  The engine 10 is not shown in detail, but the pistons are housed in the cylinder portions 11c and 12c of the pair of banks 11 and 12, the combustion chambers 13 and 14 are defined, and the intake and exhaust valves are predetermined. It is mounted so that it can be opened and closed to open at the timing. In addition, a direct ignition type ignition device having an ignition plug exposed in the combustion chambers 13 and 14 and an ignition coil for igniting the ignition plug is provided.

  The pair of banks 11 and 12 are respectively provided with intake manifolds 15 and 16 and an exhaust manifold (not shown). The intake ports 17 and 18 communicating with the intake manifolds 15 and 16 include fuel injection valves 21 for port injection, 22 is provided, and a throttle valve (not shown) is provided. A known exhaust purification device (not shown) is connected to the downstream side of the exhaust manifold of the engine 10.

  The fuel injection valves 21 and 22 for port injection are connected to a feed pump 25 for fuel supply via delivery pipes 23 and 24. Although not shown in detail, the feed pump 25 pumps up the fuel in the fuel tank 26, for example, gasoline, discharges it at the first fuel pressure level, and feeds it to the delivery pipes 23, 24 through the fuel passage 27. For example, it is a known one that is ON / OFF driven based on an ON / OFF command signal of an engine control computer 50 described later.

  The plurality of cylinders 11 c and 12 c of the engine 10 are also provided with a plurality of in-cylinder fuel injection valves 31 and 32 that inject high-pressure fuel directly into the combustion chambers 13 and 14.

  These in-cylinder fuel injection valves 31 and 32 are connected to a plunger-type pressurizing pump 35 through delivery pipes 33 and 34 and a high-pressure fuel passage 37.

  The pressurizing pump 35 has a pressurizing chamber 35a for introducing the fuel fed from the feed pump 25, and the fuel in the pressurizing chamber 35a has a second pressure higher than the first fuel pressure level. The fuel pressure level is increased and discharged to the high-pressure fuel passage 37 on the side of the fuel injection valves 31 and 32 for in-cylinder injection.

  Specifically, the pressurizing pump 35 includes a plunger 35p that is slidable in the pump housing 35h so as to change the volume of the pressurizing chamber 35a, a camshaft 35s that drives the plunger 35p, and a cam The pump housing includes a follower lifter 35f that is driven up and down in the vertical direction in the figure by a cam portion Cp of the shaft 35s, and a compression spring 35g that urges the follower lifter 35f to the cam portion Cp of the camshaft 35s. The pressurizing chamber 35a defined between 35h and the plunger 35p changes the volume by the reciprocating movement of the plunger 35p, and performs the suction, pressurization, and discharge operations of the fuel from the feed pump 25. ing. Further, the upstream end portion of the high pressure fuel passage 37 between the pressurization chamber 35a of the pressurization pump 35 and the high pressure fuel passage 37, that is, between the pressurization pump 35 and the fuel injection valves 31, 32 for in-cylinder injection. Is provided with a spring that opens when the discharge pressure of fuel discharged from the pressurizing pump 35 exceeds a specific pressure value and allows fuel to be supplied to the fuel injection valves 31 and 32 for in-cylinder injection. A check valve 36 is provided.

  The delivery pipes 23 and 24 include a known pulsation damper 28 (pressure damper) that suppresses the pressure pulsation of the fuel in the delivery pipes 23 and 24 fed from the feed pump 25 in the first pressure range. 34, a fuel pressure sensor 38 for detecting the fuel pressure and a relief valve 39 for defining the upper limit of the second pressure range are respectively attached. Further, a pulsation for suppressing pressure pulsation of fuel supplied in the first pressure range is provided on the fuel supply passage 27a branched to the pressurization chamber 35a side of the pressurization pump 35 in the fuel passage 27 from the feed pump 25. A damper 29 is arranged. Here, the relief valve 39 is any part on the high-pressure fuel passage 37 to which fuel is fed by the pressurizing pump 35 at the second fuel pressure level, for example, the fuel injection valve 31 for in-cylinder injection, It is arranged at a position where the fuel pressure inside the delivery pipes 33 and 34 close to 32 can be detected, and is opened at a set pressure that is the upper limit pressure of the fuel at the second fuel pressure level.

  The engine 10 includes fuel injection valves 21 and 22 for port injection for injecting fuel into the intake ports 17 and 18, and fuel injection valves 31 for in-cylinder injection for injecting fuel into the cylinders 11c and 12c. 32, and low pressure side delivery pipes 23, 24, a feed pump 25, a fuel tank 26 and a fuel passage 27 for supplying fuel to these fuel injection valves 21, 22, 31, 32, and a high pressure side delivery. The pipes 33 and 34, the pressurizing pump 35, and the high-pressure fuel passage 37 constitute a fuel supply means 30 that supplies fuel to the fuel injection valves 21, 22, 31, and 32.

  As shown in FIG. 2, the fuel inlet 35i of the pressurizing chamber 35a of the pressurizing pump 35 connected to the fuel supply passage 27a from the feed pump 25 has a check valve function for preventing a high-pressure backflow. An electromagnetic spill valve 40 is provided that can cause the high-pressure fuel in the pressurizing chamber 35a to leak to the low-pressure side when the valve is opened in response to an input signal.

  The electromagnetic spill valve 40 includes a poppet-like valve body 41, an electromagnetic drive coil 42 that electromagnetically drives the valve body 41, and a spring 43 that constantly biases the valve body 41 in the valve opening direction. Normally, the valve body 41 opens in response to the differential pressure between the fuel pressure fed from the feed pump 25 and the fuel pressure in the pressurizing chamber 35a for the suction operation of the pressurizing pump 35. For the discharge operation of the pressurizing pump 35, the valve closing operation is performed according to the differential pressure between the fuel pressure fed from the feed pump 25 and the fuel pressure in the pressurizing chamber 35a.

  Specifically, the valve body 41 includes a large-diameter poppet valve body portion 41a located in the pressurizing chamber 35a, and a poppet valve body portion 41a in an excited state in which an excitation current is supplied to the electromagnetic drive coil 42. The core portion 41b extends from the vicinity of the fuel introduction port portion 35i to the other end side so as to urge the valve in the valve closing direction, and the poppet valve body portion 41a has the fuel pressure in the pressurizing chamber 35a and the poppet valve body portion 41a. The valve closing direction thrust and the urging force in the valve opening direction from the spring 43 are received according to the difference in pressure receiving area on both sides in the axial direction. Therefore, the valve body 41 can be opened and closed in accordance with the change in the fuel pressure in the pressurizing chamber 35a in a non-excited state where no excitation current is supplied to the electromagnetic drive coil 42.

  On the other hand, as shown in FIG. 1, the electromagnetic spill valve 40 can be controlled by the engine control computer 50 via the driver circuit 61, and for this purpose, the electromagnetic drive coil 42 of the electromagnetic spill valve 40 is connected to the driver circuit 61. It is connected.

  The engine control computer 50 includes a backup memory including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a nonvolatile memory, although not shown in detail in the hardware configuration. An input interface circuit including a D converter, an output interface circuit including a driver and a relay switch, and a constant voltage circuit are included. This engine control computer 50 is based on a control program stored in advance in a ROM, based on sensor information, set value information stored in a backup memory, etc., and further on an in-vehicle ECU (Electronic Control Unit; electronic control). For example, the fuel injection amount corresponding to the operating state of the engine 10 or the acceleration request is calculated while communicating with the unit), and the fuel injection valves 21 and 22 for port injection and the fuel injection valves 31 and 32 for in-cylinder injection are calculated. A valve drive instruction signal to the driver circuit 61 for driving the electromagnetic injection spill valve 40 and the electromagnetic spill valve 40 are output in a timely manner.

  The engine control computer 50 adjusts at least the amount of fuel leaked from the pressurizing chamber 35a by the electromagnetic spill valve 40 (or by further adjusting the driving rotational speed of the pressurizing pump 35), thereby increasing the pressure pump 35. Thus, the pressure of the fuel supplied to the delivery pipes 33 and 34 can be controlled to an optimum fuel pressure according to the operating state of the engine 10 and the injection characteristics of the fuel injection valves 31 and 32 for in-cylinder injection. For example, the engine control computer 50 can set an ON time during which the electromagnetic drive coil 42 of the electromagnetic spill valve 40 is in an excited state and an OFF time during which the excitation state is released within a certain signal cycle. The amount of fuel leakage from the pressurizing chamber 35a by the electromagnetic spill valve 40 can be adjusted by changing the ON time ratio (0% to 100%; hereinafter referred to as duty ratio) in .

  In addition, when the engine 10 is started, the engine control computer 50 first performs fuel injection by the port injection fuel injection valves 21 and 22, and during that time, the high-pressure side delivery pipe 33 detected by the fuel pressure sensor 38, When the fuel pressure in the cylinder 34 exceeds a specific pressure value, it is determined that the second fuel pressure level required for fuel injection by the fuel injection valves 31 and 32 for in-cylinder injection can be reached. The output of the injection command signal to the fuel injection valves 31 and 32 for internal injection can be started.

  The specific pressure value mentioned here is determined in the fuel on the fuel injection valves 31 and 32 side for in-cylinder injection from / in the pressurizing chamber 35a of the pressurizing pump 35 at the time of starting the engine 10, for example, at high temperature restart. Since air is mixed in or fuel vapor is generated, the second fuel pressure level required for fuel injection by the fuel injection valves 31 and 32 for in-cylinder injection even when the pressurizing pump 35 is operated. The fuel pressure is set to about the highest pressure value among the fuel pressures obtained when the state that does not reach the state continues for a certain time or longer.

  The engine control computer 50 further has a state in which the discharge pressure from the pressurization pump 35 detected by the fuel pressure sensor 38 is equal to or lower than a specific pressure value when the engine 10 is started under the preset execution conditions. When continuing over a preset pressure determination time, the electromagnetic spill valve 40 is periodically opened to fill the pressurizing chamber 35a with fuel at the first fuel pressure level fed from the feed pump 25. Functions as an air bleeding control means.

  The execution conditions set in advance here are a neutral range, an idle operation state where the accelerator pedal is not depressed, a test operation mode at a vehicle assembly factory, and fuel injection for port injection. The dummy injection before the test operation of the valves 21 and 22 and the fuel injection valves 31 and 32 for in-cylinder injection is completed, the air bleeding control is not performed, and the fuel pressure detected by the fuel pressure sensor 38 is specified. If the fuel pressure can be increased to a specific fuel pressure even without air bleeding control by the operation of the pressurizing pump 35 after starting, the pressure judgment time sufficient to increase the pressure has elapsed. There are eight conditions, that is, that a failure of the pressurizing pump 35 is not detected.

  That is, the engine control computer 50 according to the present embodiment receives the inspection signal in the communication interface or the inspection signal input port of the engine control computer 50 and operates in the test mode as in the inspection mode operation after the assembly of the vehicle assembly factory. Only when it is determined that the state is executed, the air vent control means according to the present invention is functioned. It should be noted that the initial start time referred to in the present invention may be a start within a certain number of times immediately after assembly of the engine 10.

  The pressure determination time is set to about 5 seconds from the start of the start with respect to the detected value of the fuel pressure detected every 65 msec based on the sensor signal of the fuel pressure sensor 38, for example.

  For example, the engine control computer 50 as the air venting control means sets the electromagnetic spill valve 40 open time (OFF time in the non-excited state in this embodiment) within the certain signal period to be sufficiently long, for example, 50. % Duty ratio is set, or a valve opening time longer than the valve opening time corresponding to the duty ratio of 50% is set at a period different from the normal constant signal period, and the valve opening time Generates a valve drive instruction signal to the driver circuit 61 for driving the electromagnetic spill valve 40 so as to open the electromagnetic spill valve 40.

  Further, the engine control computer 50 as the air vent control means periodically injects the fuel injection valves 31 and 32 for in-cylinder injection in synchronization with the opening of the electromagnetic spill valve 40 when the electromagnetic spill valve 40 is periodically opened. Are opened periodically.

  Further, when the engine 10 is started and within the pressure determination time, the engine control computer 50 serving as an air vent control means supplies the fuel supplied by the feed pump 25 to the fuel injection valves 21 and 22 for port injection. When the state in which the discharge pressure of the fuel discharged from the pressurizing pump 35 remains below a specific pressure value continues beyond the pressure determination time, The injection valves 21 and 22 are closed. That is, when the engine 10 is started, when the state in which the discharge pressure of the fuel discharged from the pressurization pump 35 remains below a specific pressure value continues beyond the pressure determination time, the fuel injection valve 21 for port injection, 22 is closed, and at the stage where the second fuel pressure level necessary for fuel injection by the in-cylinder fuel injection valves 31, 32 is not reached, the in-cylinder injection fuel injection valves 31, 32 are opened. Thus, air bleeding control is executed.

  On the other hand, the engine control computer 50 as the air bleeding control means immediately stops the air bleeding control when a preset end condition is satisfied. The end condition is, for example, that the accelerator pedal is depressed to enter a non-idle operation state, and that the engine speed falls below a preset threshold speed.

  Specifically, for example, when the engine speed temporarily increases and decreases temporarily due to an idling operation at the time of start-up, the air is vented from the time when the engine speed exceeds a preset threshold speed. The control is temporarily stopped, and the stabilization time required for the engine speed to become almost stable from when the engine speed reaches the threshold speed again and falls below it is measured by an internal counter. Air bleed control is restarted from the time point. In addition, when the engine speed is suddenly lower than the target idle speed when the engine 10 is started, air bleeding control is performed from the time when the engine speed falls below a preset threshold speed. When the engine rotation speed reaches the threshold rotation speed again and exceeds the threshold rotation speed, the stabilization time required for the engine rotation speed to become almost stable is measured with an internal counter, and the stabilization time has elapsed. Therefore, the air bleeding control is resumed.

  In addition to the fuel pressure sensor 38, the input interface circuit (not shown) of the engine control computer 50 includes a crank angle sensor (rotational speed sensor), a throttle opening sensor, an air flow meter, a vehicle speed sensor, a cylinder discrimination sensor, an intake air temperature sensor, A water temperature sensor, an exhaust oxygen concentration oxygen sensor, and the like are connected, and sensor information from these sensor groups is taken into the engine control computer 50. The output interface circuit of the engine control computer 50 is connected to a drive circuit group such as an ignition drive circuit and a fuel pump drive circuit in addition to the driver circuit 61 for driving the injection. Since they are similar, they will not be described in detail here.

  Next, the operation will be described.

  FIG. 3 is a timing chart showing an outline procedure of the air bleeding control at the time of initial engine start in the fuel supply device for the internal combustion engine of the present embodiment.

  When the engine 10 is started, first, the engine control computer 50 operates the feed pump 25 and closes the in-cylinder injection fuel injection valves 31 and 32, and the port injection fuel injection valves 21 and 22. Is opened and fuel injection is performed by the fuel injection valves 21 and 22 for port injection.

  Then, during the time set as the pressure determination time from the start of the port injection, it is checked whether or not the fuel pressure in the high-pressure delivery pipes 33 and 34 detected by the fuel pressure sensor 38 has exceeded a specific pressure value. Is done.

  Usually, during the pressure determination time ta from the start of the port injection, the fuel pressure in the delivery pipes 33 and 34 detected by the fuel pressure sensor 38 exceeds a specific pressure value, so the fuel pressure in the delivery pipes 33 and 34 When the engine control computer 50 determines that the fuel pressure in the delivery pipes 33 and 34 is higher than the specific pressure value, the fuel pressure in the delivery pipes 33 and 34 is the second required for fuel injection by the fuel injection valves 31 and 32 for in-cylinder injection. It is determined that the fuel pressure level can be reached, and then output of the injection command signal to the fuel injection valves 31 and 32 for in-cylinder injection is started.

  On the other hand, when the engine 10 is started, air is mixed into the fuel in the pressurizing chamber 35a of the pressurizing pump 35 and / or from the fuel injection valves 31 and 32 for in-cylinder injection, or fuel vapor is generated. In this case, as shown in FIG. 3 (d), even if the pressurization pump 35 is operated from the start of port injection, the fuel by the fuel injection valves 31 and 32 for in-cylinder injection during the pressure determination time ta. A state where the second fuel pressure level necessary for injection is not reached may continue for a certain period of time.

  In such a case, the state in which the discharge pressure from the pressurizing pump 35 becomes a specific pressure value or less continues beyond the pressure determination time ta, and the fuel pressure in the delivery pipes 33 and 34 detected by the fuel pressure sensor 38 When it is determined that the specific pressure value is not exceeded, the engine control computer 50 periodically opens the electromagnetic spill valve 40 and injects fuel for in-cylinder injection in synchronization with the opening timing of the electromagnetic spill valve 40. By periodically opening the valves 31, 32, air venting control is performed to fill the pressurizing chamber 35 a of the pressurizing pump 35 with fuel at the first fuel pressure level from the feed pump 25.

  That is, as shown in FIG. 3C, the electromagnetic spill valve 40 is shown in FIG. 3C during the air bleed control period shown in FIGS. 3A and 3B as “bleed control ON” and “direct injection 100%”. For example, a duty ratio of 50% is set so that the valve opening time is sufficiently long, or the valve opening time longer than the valve opening time corresponding to the duty ratio of 50% is different from the normal constant signal period. Time (OFF time) is set. Therefore, during the valve opening time, the electromagnetic spill valve 40 is continuously opened, and the fuel at the first fuel pressure level from the feed pump 25 is sufficiently supplied into the pressurizing chamber 35a and the pressurizing chamber. Even if the fuel flows out from the fuel injection valve 31 and 32 to the side of the fuel injection valve 35a and the fuel at the first fuel pressure level from the feed pump 25 is mixed into the pressurizing chamber 35a of the pressurizing pump 35, Air is reliably discharged downstream.

  Further, by alternately setting the valve opening time and the valve closing time of the electromagnetic spill valve 40, fuel flows from the feed pump 25 into the pressurizing chamber 35a, and the check valve 36 is passed from the pressurizing pump 35. The fuel is alternately discharged and the fuel is reliably discharged to the high-pressure fuel passage 37 side on the delivery pipes 33 and 34 side. Accordingly, the time during which the discharge pressure from the pressurizing pump 35 cannot be increased when the engine 10 is started is prolonged, and it is possible to prevent the startability, particularly the high temperature restartability, from being deteriorated.

  By the way, when the engine 10 is started, a so-called racing state in which the engine speed temporarily rises and falls temporarily due to an idling operation may occur. In such a case, as shown in FIG. 4, the engine speed is set to a preset threshold speed (speed higher than the idling speed ntcal; see FIGS. 4A and 4B). The air bleeding control is temporarily suspended from the point of time exceeding (see FIGS. 4B and 4D). Then, from the time when the engine speed reaches the threshold speed again and falls below it, the stabilization time required for the engine speed to be substantially stabilized is measured by the counter A, and from the time when the stabilization time has elapsed, The removal control is resumed (see FIGS. 4B to 4D).

  Further, as shown in FIG. 5, when the engine speed suddenly drops below the idle speed (see FIG. 5 (a)), and the possibility that engine stall will occur increases, The air bleeding control is temporarily stopped from the time when the number falls below a preset threshold rotation speed. When the engine speed reaches the threshold rotational speed again, the stabilization time required for the engine rotational speed to be substantially stabilized from the time when the engine rotational speed exceeds the threshold rotational speed again is measured by the counter B. When the time has elapsed, the air bleeding control is resumed (see FIGS. 5B and 5C).

  As described above, in the fuel supply device for the internal combustion engine of the present embodiment, when the discharge pressure from the pressurizing pump 35 becomes a specific pressure value or less during the initial start of the engine 10 continues beyond the pressure determination time. Since the electromagnetic spill valve 40 is periodically opened long to fill the pressurizing chamber 35a with the fuel at the first fuel pressure level from the feed pump 25, the fuel is filled into the pressurizing chamber 35a. The pressure pump 35 can be sufficiently supplied and allowed to flow out from the pressurizing chamber 35a to the fuel injection valves 31 and 32 for in-cylinder injection, so that the pressurizing pump 35 can be surely vented. The fuel pressure in the fuel passage 37 can be reliably increased to the fuel pressure required for in-cylinder injection. As a result, in the vehicle assembly plant, the MIL, which is an abnormality warning lamp, is turned on due to an abnormality in the fuel pressure, and the troublesome work of turning off the MIL by taking the vehicle that has reached the inspection process after assembly from the production / inspection line. Therefore, the conventional problem that the vehicle is required can be solved, and the production efficiency of the vehicle can be improved.

  Such a fuel supply device for an internal combustion engine according to the present invention is a dual injection type that uses both a fuel injection valve for port injection and a fuel injection valve for in-cylinder injection, and can release air from the high-pressure fuel passage. Useful for all fuel supply systems.

1 is a schematic configuration diagram of a fuel supply device for an internal combustion engine according to an embodiment of the present invention. It is a principal part enlarged view of the fuel supply apparatus which concerns on one Embodiment of this invention. 3 is a timing chart showing an outline procedure of air bleeding control at the time of initial engine start in the fuel supply apparatus for an internal combustion engine according to the embodiment of the present invention. 3 is a timing chart illustrating a temporary stop condition of air bleeding control in the fuel supply apparatus for an internal combustion engine according to the embodiment of the invention. It is a timing chart which illustrates other temporary stop conditions of air bleeding control in the fuel supply device of an internal-combustion engine concerning one embodiment of the present invention.

Explanation of symbols

10 Engine 11, 12 Bank 11c, 12c Cylinder 13, 14 Combustion chamber 15, 16 Intake manifold 17, 18 Intake port 21, 22 Fuel injection valve for port injection 23, 24 Delivery pipe 25 Feed pump 26 Fuel tank 27 Fuel passage 27a Fuel supply passages 28, 29 Pulsation damper 30 Fuel supply means 31, 32 Fuel injection valve for in-cylinder injection 33, 34 Delivery pipe 35 Pressurization pump 35a Pressurization chamber 35f Follower lifter 35g Compression spring 35h Pump housing 35i Fuel introduction port 35p Plunger 35s Camshaft 36 Check valve 37 High pressure fuel passage 38 Fuel pressure sensor 39 Relief valve 40 Electromagnetic spill valve 41 Valve element 42 Electromagnetic drive coil 50 Engine control computer (Air venting control) Means)
61 Driver circuit

Claims (1)

A fuel injection valve for injecting fuel into an intake port of the internal combustion engine, a fuel injection valve for in-cylinder injection for injecting the fuel into a cylinder of the internal combustion engine, and the fuel into both fuel injection valves A fuel supply means for supplying the fuel, and the fuel supply means is fed from the feed pump for feeding the fuel to the fuel injection valve for port injection at a first fuel pressure level. A pressurizing pump having a pressurizing chamber for introducing fuel, pressurizing the fuel in the pressurizing chamber to a second fuel pressure level higher than the first fuel pressure level, and discharging the fuel to the fuel injection valve side; A fuel supply device for an internal combustion engine having an electromagnetic spill valve that opens in response to an input signal and leaks fuel in the pressurized chamber,
The electromagnetic spill valve opens in response to a differential pressure between the fuel pressure fed from the feed pump and the fuel pressure in the pressurizing chamber with respect to the suction operation of the pressurizing pump, and the pressurization A valve body that performs a valve closing operation according to a differential pressure between a fuel pressure fed from the feed pump and a fuel pressure in the pressurizing chamber with respect to a discharge operation of the pump;
A pressure determination time that is set in advance is a state in which the discharge pressure of the fuel discharged from the pressurizing pump is equal to or lower than a specific pressure value that does not reach the second fuel pressure level when the internal combustion engine is initially started. When continuing beyond, air vent control means is provided for periodically opening the electromagnetic spill valve to fill the pressurized chamber with fuel of the first fuel pressure level fed from the feed pump. A fuel supply device for an internal combustion engine.

Images