JP2006200423A - Fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent troubles such as deterioration of startability of an engine, drop of engine output, or engine stall beforehand by preventing fuel pumping defect due to mixing of air such as babbles. <P>SOLUTION: Mixing quantity of air such as babble mixed into fuel is estimated based on pressure detection value of a fuel pressure sensor 11. If estimated mixing quantity of air is a criterion or greater, a solenoid valve 14 of air bleeding mechanism 7 is opened to return air such as babble into a fuel tank 3 from an air reservoir chamber provided in an upper part of a fuel filter 6 via an air bleeding piping 69 and an over flow piping 20. Consequently, since air such as babble sucked from a suction opening of a low pressure fuel piping 41 is removed from fuel supply line for supplying low pressure fuel into a fuel pressurizing chamber 31 of a supply pump 4, air such as babble is not sucked into a fuel pressurizing chamber 31 of the supply pump 4 and fuel pumping defect due to mixing of air such as babble can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, fuel pumped up from a fuel tank by a low-pressure fuel pump such as a feed pump is further pressurized by a high-pressure fuel pump such as a fuel injection pump so as to be pressurized and supplied to the fuel injection valve side of the internal combustion engine. In particular, the present invention relates to a fuel supply device for an internal combustion engine, in which high pressure fuel discharged from a discharge port of a high pressure fuel pump is accumulated in a common rail, and the high pressure fuel accumulated in the common rail is stored in the internal combustion engine via a fuel injection valve. The present invention relates to a pressure accumulation type fuel injection device configured to inject and supply into a combustion chamber.

[Conventional technology]
2. Description of the Related Art Conventionally, for example, a fuel supply device for an internal combustion engine such as a diesel engine has a feed pump and a fuel injection pump sequentially provided in a fuel supply path from a fuel tank to a fuel injection valve (fuel injection nozzle) for an internal combustion engine or a common rail. The surplus fuel from the fuel injection nozzle or common rail or fuel injection pump is returned to the fuel tank via an overflow pipe (fuel recirculation path) (for example, Patent Documents 1 to 3). reference).

[Conventional technical problems]
However, in the conventional fuel supply device for an internal combustion engine, when excess fuel is dropped into the fuel tank from the outlet of the overflow pipe, the stored fuel in the fuel tank is bubbled and bubbles are generated. If the outlet of the overflow pipe is arranged in the fuel tank near the suction port of the low-pressure fuel pipe, air such as bubbles generated by dropping excess fuel from the outlet of the overflow pipe is sucked into the low-pressure fuel pipe. It is sucked from the mouth and sucked into the feed pump.

  Then, air such as bubbles mixed in the fuel sucked from the suction port of the low-pressure fuel pipe is discharged from the discharge side of the feed pump and sucked into the fuel pressurizing chamber of the fuel injection pump. For this reason, since the amount of fuel sucked is substantially insufficient by the volume of air such as bubbles, the amount of fuel pumped from the discharge port of the fuel injection pump to the fuel injection nozzle is substantially equal to the volume of air. Will be lacking. Therefore, poor fuel pumping occurs, and the injection characteristics of the fuel injection amount change, which can deteriorate engine startability, reduce engine output, and induce engine stall (engine stall). There was sex.

  Further, in the conventional fuel supply device for an internal combustion engine, a fuel filter is installed on the upstream side in the fuel flow direction from the suction side of the feed pump. That is, when a feed pump is installed between the downstream side in the fuel flow direction with respect to the fuel filter and the upstream side in the fuel flow direction with respect to the fuel injection pump, the low pressure fuel on the downstream side in the fuel flow direction with respect to the fuel filter. The pressure in the piping becomes negative due to the suction of the feed pump, and bubbles are likely to be generated in the fuel. For this reason, negative pressure is generated by the suction of the feed pump, air in the fuel is separated into large bubbles, and is sucked into the feed pump, causing the same problem as described above.

It is conceivable that the fuel intake amount or the fuel pumping amount is increased by a certain amount so that the above-described fuel pumping failure does not occur, but the air mixing amount such as bubbles varies depending on the engine operating conditions. Therefore, in some cases, more fuel than necessary is supplied from the discharge side of the feed pump into the fuel pressurization chamber of the fuel injection pump, which may cause deterioration of fuel consumption due to excessive pumping.
JP 2000-145574 (page 1-6, FIGS. 1 to 4) JP 2000-064924 A (page 1-6, FIGS. 1 to 4) JP 2003-184704 A (page 1-6, FIGS. 1 to 3)

  The object of the present invention is to prevent or avoid fuel pumping failure due to air mixing such as air bubbles and prevent problems such as deterioration of startability of the internal combustion engine, reduction of engine output, engine stall, etc. An object of the present invention is to provide a fuel supply device for an internal combustion engine. Another object of the present invention is to provide a fuel supply device for an internal combustion engine that can avoid or prevent excessive pumping of fuel and suppress deterioration of fuel consumption.

  According to the first aspect of the present invention, the fuel sucked from the suction port of the low-pressure fuel pipe by the pressure detection means is discharged from the high-pressure fuel pump through the inside of the low-pressure fuel pump and the pressurizing chamber of the high-pressure fuel pump. The fuel pressure in the fuel supply path for supplying to the outlet is detected. Then, based on the pressure detection value of the pressure detection means, the low-pressure fuel sucked into the fuel sucked from the suction port of the low-pressure fuel pipe, the fuel sucked into the low-pressure fuel pump, or the pressurized chamber of the high-pressure fuel pump The amount of air contamination such as bubbles mixed in (or generated) is estimated (air contamination amount estimation means). Therefore, it is possible to estimate the amount of air mixed in such as bubbles that are difficult to measure by a simple method. Then, for example, an air venting mechanism or a fuel pressurizing mechanism may be operated based on the estimated air mixing amount (air mixing amount estimated value).

  According to the invention described in claim 2, by operating the air venting mechanism based on the estimated air mixing amount (the air mixing amount estimated value), the fuel sucked from the suction port of the low pressure fuel pipe or the low pressure fuel Air such as bubbles mixed (or generated) in the fuel sucked into the pump or in the low-pressure fuel sucked into the pressurized chamber of the high-pressure fuel pump is upstream in the fuel flow direction from the pressurized chamber of the high-pressure fuel pump. Is removed from the side fuel supply path.

  As a result, air such as bubbles mixed in the fuel sucked into the low pressure fuel pump from the suction port of the low pressure fuel pipe is not sucked, or from the discharge side of the low pressure fuel pump into the pressurizing chamber of the high pressure fuel pump. The high-pressure fuel with a sufficient discharge volume that has been pressurized in the pressurization chamber of the high-pressure fuel pump without sucking air such as bubbles mixed (or generated) into the fuel to be sucked in the fuel injection valve side of the internal combustion engine (Or common rail side, etc.) can be pumped. Thereby, since poor pumping of fuel due to mixing of air such as bubbles can be avoided or prevented, problems such as deterioration of startability of the internal combustion engine, reduction of engine output, engine stall, etc. can be prevented. In addition, since a method of raising the fuel intake amount or the fuel pumping amount by a certain amount is not employed so that fuel pumping failure does not occur, deterioration of fuel consumption due to excessive pumping of the high-pressure fuel pump can be prevented. it can.

  According to the invention described in claim 3, by providing the air vent pipe in the air vent mechanism, the fuel sucked from the suction port of the low pressure fuel pipe, the fuel sucked into the low pressure fuel pump, or the high pressure Air bubbles such as bubbles mixed (or generated) in the low-pressure fuel sucked into the pressurized chamber of the fuel pump are routed from the fuel supply path upstream of the pressurized chamber of the high-pressure fuel pump through the air vent pipe. Can be removed.

  According to the fourth aspect of the present invention, the upstream end of the air vent pipe in the air flow direction is connected to a space provided upstream of the pressurizing chamber of the high pressure fuel pump in the fuel flow direction. In this case, the air in the air vent pipe is placed in a space (air pool chamber) where air such as bubbles is provided in the upper part of the fuel supply path such as the low pressure fuel pipe (for example, the top side in the vertical direction such as the low pressure fuel pipe). It is desirable to connect the upstream ends in the flow direction.

  According to the fifth aspect of the present invention, the fuel filter may be installed upstream of the pressurizing chamber of the high-pressure fuel pump in the fuel flow direction. In particular, a fuel filter may be installed upstream of the suction side of the low-pressure fuel pump in the fuel flow direction. The upstream end of the air vent pipe in the air flow direction is provided at the upper part of the fuel filter (top side of the fuel filter in the vertical direction), where air such as bubbles easily collects and has a large internal volume (air reservoir). It is desirable to connect to the room.

  According to the invention described in claim 6, the air vent mechanism is provided with the air vent control valve for opening and closing the air vent path in the air vent pipe. Then, when the estimated air mixing amount of the air mixing amount estimating means is equal to or greater than a predetermined value, the air vent control valve is opened, so that the fuel sucked from the suction port of the low pressure fuel pipe or inside the low pressure fuel pump Air such as bubbles mixed (or generated) in the sucked fuel or the low pressure fuel sucked into the pressurized chamber of the high pressure fuel pump is supplied to the fuel upstream of the pressurized chamber of the high pressure fuel pump. It can be removed from the path via the air vent path in the air vent pipe.

  According to the seventh aspect of the present invention, the air vent mechanism is provided with a vacuum device that sucks air mixed in the fuel supplied into the pressurized chamber of the high-pressure fuel pump into the air vent path in the air vent pipe. ing. Then, when the estimated air mixing amount of the air mixing amount estimating means is equal to or larger than a predetermined value, the vacuum device is operated to be sucked into the fuel sucked from the suction port of the low pressure fuel pipe or into the low pressure fuel pump. Air such as bubbles mixed (or generated) in the low-pressure fuel sucked into the fuel or in the pressurized chamber of the high-pressure fuel pump from the fuel supply path upstream of the pressurized chamber of the high-pressure fuel pump in the fuel flow direction. It can be reliably removed via the air vent path in the air vent pipe.

  According to the eighth aspect of the present invention, by operating the fuel pressurizing mechanism based on the estimated air mixing amount of the air mixing amount estimating means, the fuel is sucked from the suction port of the low pressure fuel pipe, or the low pressure Even when air such as bubbles is mixed in the fuel sucked into the fuel pump or the low-pressure fuel sucked into the pressurized chamber of the high-pressure fuel pump, an appropriate amount of fuel is always inhaled in the pressurized chamber of the high-pressure fuel pump. Will be supplied to. In addition, the amount of fuel that is discharged from the discharge side of the low-pressure fuel pump and sucked into the pressurized chamber of the high-pressure fuel pump by the amount of air mixed in the fuel sucked into the low-pressure fuel pump. By operating the fuel pressurizing mechanism so as to compensate for the shortage, it is possible to suppress deterioration in fuel consumption due to excessive pumping while avoiding poor pumping of fuel due to air mixing such as bubbles.

  According to the ninth aspect of the present invention, an electric pump installed upstream of the suction side of the low-pressure fuel pump in the fuel flow direction may be used as the fuel pressurizing mechanism. For example, an in-tank type electric pump installed in the fuel tank may be used as the fuel pressurizing mechanism. And the pump efficiency of an electric pump is controlled based on the air mixing amount estimated value of an air mixing amount estimation means. As a result, the amount of fuel that is discharged from the discharge side of the low-pressure fuel pump and sucked into the pressurization chamber of the high-pressure fuel pump by the amount of air mixed in the fuel sucked into the low-pressure fuel pump. Since the pump efficiency of the electric pump can be controlled so as to compensate for the shortage of fuel, it is possible to suppress deterioration in fuel consumption due to excessive pumping while avoiding poor pumping of fuel due to air mixing such as bubbles.

  According to the invention described in claim 10, a fuel pressure sensor for detecting the fuel pressure on the suction side or the discharge side of the low pressure fuel pump may be installed in the low pressure fuel pump. Or you may install the fuel pressure sensor which detects the fuel pressure of the pressurization chamber or discharge port of a high pressure fuel pump in a high pressure fuel pump. In particular, when a fuel filter is installed upstream of the suction side of the low-pressure fuel pump in the fuel flow direction, pressure pulsation is likely to occur and the pressure in the fuel supply path varies from negative pressure to positive pressure. It is desirable to install a fuel pressure sensor on the discharge side of the fuel pump.

  According to the eleventh aspect of the present invention, the low pressure fuel pump is a feed that pumps up the normal pressure fuel in the fuel tank and discharges the low pressure fuel to the high pressure fuel pump by changing the interdental volume between the inner rotor and the outer rotor. A pump may be employed. As a high-pressure fuel pump, the plunger is slid back and forth in the cylinder, so that the low-pressure fuel discharged from the discharge side of the feed pump is sucked into the pressurized chamber and the high-pressure fuel is discharged to the fuel injection valve side of the internal combustion engine. You may adopt a supply pump. In particular, by assembling the feed pump integrally with the supply pump, there is no need for a low-pressure fuel pipe connecting the discharge side of the feed pump and the suction port of the supply pump. Since the outer rotor and the plunger of the supply pump can be driven, the number of parts can be reduced.

  The best mode for carrying out the present invention is to prevent poor pumping of fuel due to air and other air bubbles, and prevent problems such as deterioration in startability of the internal combustion engine, reduction in engine output, engine stall, etc. The purpose is to estimate the amount of air mixed in the fuel by the pressure detection value of the pressure detection means, and operate the air venting mechanism based on this air mixing amount estimated value to supply the air mixed in the fuel. Realized by removing from the path. In addition, the fuel pressurization mechanism is controlled in consideration of the amount of air mixed in the fuel for the purpose of suppressing deterioration in fuel consumption due to excessive pumping while avoiding poor fuel pumping due to air mixing such as bubbles. That was realized.

[Configuration of Example 1]
FIGS. 1 to 7 show a first embodiment of the present invention. FIG. 1 is a diagram showing a main configuration of a common rail fuel injection system, and FIG. 2 is a diagram showing an overall configuration of the common rail fuel injection system. 3 and 4 are diagrams showing the overall configuration of the supply pump.

  The fuel supply device for an internal combustion engine of the present embodiment is a common rail fuel injection system (fuel injection device for an internal combustion engine) known as a fuel injection system for an internal combustion engine (hereinafter referred to as an engine) such as a multi-cylinder diesel engine. The high-pressure fuel accumulated in the common rail 1 is configured to inject and supply high-pressure fuel into the combustion chamber of each cylinder of the engine via an injector mounted corresponding to each cylinder of the engine.

  This common rail type fuel injection system includes a common rail 1 for accumulating high pressure fuel corresponding to the fuel injection pressure, and a plurality of internal combustion engine fuel injections that inject high pressure fuel into a combustion chamber of each cylinder of the engine at a predetermined timing. Mixed into the valve (for example, an electromagnetic fuel injection valve: hereinafter referred to as an injector) 2, a supply pump 4 that pressurizes the fuel supplied from the fuel tank 3 to increase the pressure, and the fuel supplied to the supply pump 4 An air vent mechanism 7 having an air recirculation path for returning air such as air bubbles to the fuel tank 3, and an engine control unit (engine control device: hereinafter referred to as ECU) 10 for controlling the entire fuel injection system including the engine And.

  Here, the ECU 10 is configured to include functions of a CPU that performs control processing and arithmetic processing, a storage device that stores various programs and data (memory such as ROM or EEPROM, RAM or static RAM (SRAM)), and the like. A well-known microcomputer is provided. Then, when an ignition switch (not shown) is turned on (IG / ON), the ECU 10 reads detection signals from various sensors such as the fuel pressure sensor 11 and data stored in the memory, and controls stored in the memory. Based on the program, the actuators (electromagnetic valves 12 and the like) of the plurality of injectors 2, the electromagnetic valve 13 of the supply pump 4, and the electromagnetic valve 14 of the air vent mechanism 7 are electronically controlled. In addition, the detection signal (pressure detection value) output from the fuel pressure sensor 11 and sensor signals from other various sensors are A / D converted by the A / D converter and then input to the microcomputer. It is configured. In the present embodiment, various sensors such as a crank angle sensor, an accelerator opening sensor, a cooling water temperature sensor, a fuel temperature sensor, and a common rail pressure sensor are electrically connected to the ECU 10.

  Since the high pressure fuel corresponding to the fuel injection pressure needs to be constantly stored in the common rail 1, the high pressure fuel is pumped and supplied from the supply pump 4 via the high pressure fuel pipe (fuel pumping path) 19. The common rail 1 is provided with a pressure limiter 8 for opening the common rail pressure when the common rail pressure exceeds the limit set pressure to keep the common rail pressure below the limit set pressure. The injector 2 includes a fuel injection nozzle in which a nozzle needle is slidably accommodated in a nozzle body, an electromagnetic valve 12 that drives the nozzle needle in a valve opening direction, and a needle such as a spring that biases the nozzle needle in a valve closing direction. Force means.

  The fuel injection from the injector 2 into the combustion chamber of each cylinder of the engine increases or decreases the fuel pressure in the back pressure control chamber that controls the operation of the command piston that is linked to the nozzle needle that is slidably supported in the nozzle body. Electronic control is performed by energizing and deenergizing the solenoid valve 12 to be controlled. That is, while the solenoid valve 12 of the injector 2 is energized and the nozzle needle is opened, the high-pressure fuel accumulated in the common rail 1 is injected into the combustion chamber of each cylinder of the engine from the injection hole formed on the tip end side of the nozzle body. Is supplied by injection. As a result, the engine is operated. Here, the leaked fuel overflowing from the sliding portions of the injector 2 and the sliding portions of the supply pump 4 and the surplus fuel flowing out of the common rail 1, the injector 2, the supply pump 4 and the pressure limiter 8 are overflow piping ( It is returned to the low pressure side (fuel tank 3) of the fuel system via the fuel recirculation path) 20.

  The supply pump 4 of this embodiment includes a feed pump (low pressure fuel pump) 5 that pumps up the normal pressure fuel stored in the fuel tank 3 by changing the interdental volume between the inner rotor 21 and the outer rotor 22. This is a fuel injection pump in which a pump element (high pressure fuel pump) constituted by a cylinder head (cylinder) 23 and two plungers 24 is integrated. Further, the supply pump 4 includes two pumping systems (pump elements) that pressurize the fuel sucked from the suction port 25 and pump the fuel from the discharge port 26 to the injector side. This is a fuel injection pump of a type (suction metering type) that controls the fuel pumping amount or the fuel discharge amount by metering the fuel suction amount.

  The supply pump 4 is provided with a pump drive shaft (drive shaft or camshaft) 27 that is rotationally driven by the engine. A drive pulley (not shown) is connected to the outer periphery of the axial tip of the pump drive shaft 27 (the left end shown in FIGS. 2 and 3) via a belt and a crank pulley of the engine crankshaft. Is attached. Further, the feed pump 5 is assembled to the axial rear end of the pump drive shaft 27 (the right end shown in FIGS. 2 and 3). The pump drive shaft 27 is rotatably supported by the pump housing 29 via a journal bearing 28. Two cylinder heads 23 are fastened and fixed to the upper and lower end surfaces of the pump housing 29 using fasteners such as bolts.

  Two plungers 24 are slidably accommodated in the sliding holes of the two cylinder heads 23, respectively. The internal space formed by the opening end sides of the sliding holes of the two cylinder heads 23, the end faces of the two plungers 24, and the end faces of the two suction valves 30 is in the sliding hole of the cylinder head 23. The two fuel pressurizing chambers 31 are configured to pressurize the fuel sucked by reciprocating and sliding the plunger 24 to increase the pressure. The fuel sucked from the suction port 25 flows into the two fuel pressurizing chambers 31 via the feed pump 5 → the electromagnetic valve 13 → the two suction valves 30. Further, the fuel pressurized in the two fuel pressurizing chambers 31 flows out from the discharge port 26 to the common rail 1 via the two discharge valves 32.

  The two intake valves 30 are valve bodies that close when the fuel pressure in the two fuel pressurizing chambers 31 rises above a predetermined value, and valve bodies such as springs that bias the valve bodies in the valve closing direction. This is a check valve that has urging means and prevents backflow of fuel from the two fuel pressurizing chambers to the fuel intake path on the solenoid valve side. The two discharge valves 32 are a valve body that opens when the fuel pressure in the two fuel pressurizing chambers 31 rises above a predetermined value, and a valve body such as a spring that biases the valve body in the valve closing direction. It is a check valve which has an urging means and prevents the fuel from flowing backward from the discharge port side to the fuel pressurizing chamber side.

  Here, the plunger drive means (power transmission mechanism) of the present embodiment is constituted by a cam 33, a cam ring 34, a bush 35, and the like. A cam 33 is integrally formed on the outer periphery of the intermediate portion of the pump drive shaft 27. The cam 33 has a symmetrical position in the vertical direction in the figure, and the phases of the suction process and the pumping process are opposite to each other. The two plungers 24 are arranged so as to be in phase. The cam 33 is provided eccentric to the axis of the pump drive shaft 27 and has a circular cross section. A cam ring 34 having a substantially rectangular outer shape is slidably held on the outer periphery of the cam 33 via an annular bush 35.

  A hollow portion having a circular cross section is formed inside the cam ring 34, and the cam 33 and the bush 35 are accommodated therein. Further, the two plungers 24 are pressed against the upper and lower end surfaces of the cam ring 34 by the urging force of the coil spring 36 disposed on the outer peripheral side of the two plungers 24. With this configuration, when the cam 33 integrated with the pump drive shaft 27 rotates, the cam ring 34 revolves along a predetermined circular path. The two plungers 24 are reciprocated by the cam 33 via the cam ring 34 as the pump drive shaft 27 rotates, and pressurize the fuel sucked into the two fuel pressurizing chambers 31 to increase the pressure.

  The feed pump 5 is a trochoid pump (low pressure fuel pump) that draws normal pressure fuel stored in the fuel tank 3 from the suction side and pressurizes and discharges the fuel by rotating the pump drive shaft 27. The pump housing 29 of the supply pump 4 is integrally assembled. As shown in FIGS. 1 to 3, the feed pump 5 is installed upstream of the solenoid valve 13 of the supply pump 4 in the fuel flow direction and downstream of the fuel filter 6 in the fuel flow direction. Yes. In FIG. 2, the feed pump 5 is disclosed in a form developed by 90 degrees. Further, as the feed pump 5, a vane pump may be used instead of the trochoid pump.

  The feed pump 5 includes an inner rotor 21 attached to an axial rear end of the pump drive shaft 27 and an outer rotor 22 that forms a variable volume space 37 between the inner rotor 21 and the pump housing 29. A pump cover 38 is rotatably accommodated. The variable volume space 37 forms the inside (interdental space) of the feed pump 5. Further, the pump cover 38 is configured such that the inner rotor 21 and the outer rotor 22 are accommodated and held in a circular space formed between the pump housing 29 and a flange portion provided on an outer peripheral portion thereof is on the pump housing 29 side. It is fastened and fixed to the wall surface with a fastener such as a bolt via a pump plate 39. The pump plate 39 is formed with a substantially arc-shaped suction port (suction side) and a substantially arc-shaped discharge port (discharge side).

  The fuel in the fuel tank 3 is sucked into the suction port of the low-pressure fuel pipe (fuel suction path) 41 by the relative rotation of the inner rotor 21 and the outer rotor 22 of the feed pump 5 with the rotation of the pump drive shaft 27. And is introduced into the fuel introduction path 44 via the suction port 25 formed in the fuel filter 6, the low-pressure fuel pipe (fuel suction path) 42, and the inlet pipe 43. Inhaled into the suction chamber. Further, the fuel discharged from the discharge side (discharge chamber) of the feed pump 5 is supplied to the inlet portion of the electromagnetic valve 13 (suction port of the supply pump 4) via the fuel lead-out path 45.

  The fuel discharged from the discharge side of the feed pump 5 is also supplied into the accommodating chamber 49 by bypassing the electromagnetic valve 13 or via the electromagnetic valve 13, the fuel outlet path 46 and the orifice 47. Here, a pump drive shaft 27, two plungers 24, a cam 33 and a cam ring 34 are accommodated in the accommodation chamber 49. The accommodating chamber 49 functions as a cam chamber that accommodates the cam 33 and the cam ring 34 rotatably. In the housing chamber 49, the interior of the housing of the supply pump 4, such as between the pump drive shaft 27 and the pump housing 29, between the two plungers 24 and the cam ring 34, and between the cam 33 and the cam ring 34, etc. The fuel for lubricating the sliding portions of the motor is supplied from the feed pump 5 bypassing the electromagnetic valve 13 or via the electromagnetic valve 13. Further, surplus fuel that has flowed out of the storage chamber 49 is returned to the fuel tank 3 via the overflow pipe 20.

  In the vicinity of the feed pump 5, the fuel pressure in the fuel outlet path 45 (that is, the discharge pressure of the feed pump 5) for supplying low-pressure fuel from the discharge side of the feed pump 5 to the solenoid valve 13 is a predetermined fuel pressure. A pressure regulating valve (regulating valve) 51 is provided to prevent the pressure from exceeding the value. The regulating valve 51 is installed between the fuel recirculation paths 52 and 53 communicating with the fuel lead-out path 45, and closes when the fuel pressure in the fuel lead-out path 45 rises above a predetermined value. It has valve body urging means such as a spring for urging the body in the valve closing direction, and also functions as a check valve for preventing the fuel from flowing backward from the suction side of the feed pump 5 to the fuel outlet path side. When the fuel pressure in the fuel lead-out path 45 becomes higher than a predetermined fuel pressure, the valve body of the regulating valve 51 opens against the biasing force of the spring, and excess fuel is sucked into the feed pump 5. Reflux to the side.

  The electromagnetic valve 13 corresponds to an electromagnetic intake metering valve, and a spool valve (valve element) that changes the opening area of the inlet port or outlet port, and the spool valve in the valve closing direction (or valve opening direction). A solenoid coil to be driven, a stator core and a moving core that are magnetized when the solenoid coil is energized, a spring that biases the spool valve in the valve opening direction (or the valve closing direction), and a valve that slidably accommodates the spool valve And a case. The stator core is provided with a suction portion that sucks the moving core. Further, the solenoid coil functions as valve body driving means for driving the spool valve in the valve closing direction (or valve opening direction). Further, the spring functions as valve body urging means for urging the spool valve in the valve opening direction (or valve closing direction).

  The fuel flowing out from the outlet of the electromagnetic valve 13 is configured to be distributed and supplied to the two fuel pressurizing chambers 31. That is, the fuel flowing out from the outlet of the electromagnetic valve 13 is sucked into the two fuel pressurizing chambers 31 via the two fuel suction paths 54 and the two suction valves 30. The supply pump 4 of the present embodiment adjusts the intake amount of fuel supplied from the feed pump 5 to the two fuel pressurizing chambers 31 by the electromagnetic valve 13 in accordance with the operating state of the engine. The amount of fuel discharged from the two fuel pressurizing chambers 31 through the two fuel discharge paths 55, the two discharge valves 32, and the discharge port (discharge port of the supply pump 4) 26 of the outlet pipe 56 is as follows. Adjusted. As a result, the fuel pressure in the common rail 1 is controlled to an optimum value. Excess fuel overflowing from the electromagnetic valve 13 is returned to the suction side of the feed pump 5 via the fuel recirculation path 57 and the fuel introduction path 44.

  As shown in FIGS. 1 and 2, the fuel filter 6 is disposed upstream of the suction port 25 formed in the inlet pipe 43 of the supply pump 4 in the fuel flow direction, that is, of the electromagnetic valve 13 of the supply pump 4. It is installed upstream of the inlet portion (suction port of the supply pump 4) and the suction side of the feed pump 5 in the fuel flow direction. As shown in FIG. 5, the fuel filter 6 includes a cylindrical filter element 61, a filter case 62 that accommodates the filter element 61, and the like.

  The filter element 61 includes a filter medium such as filter paper or a honeycomb-shaped filter element installed in a cylindrical space 64 formed between the inner wall surface of the filter case 62 and a flow path pipe 63 of a cylindrical tube. 3 to remove impurities contained in the fuel sucked into the suction side of the feed pump 5 (hazardous substances: solids such as dust, rust, sludge and moisture such as carbon and gum) . Further, the filter case 62 is cleaned by an inlet (inlet port) 65 for introducing fuel from the fuel tank 3 into the cylindrical space 64 via the low-pressure fuel pipe 41 and filtered by the filter element 61. An outlet (outlet side port) 66 for leading the fuel to the suction port 25 of the supply pump 4 via the low-pressure fuel pipe 42 is formed.

  Here, as shown in FIGS. 1 and 2, if the surplus fuel that has flowed out of the injector 2, the supply pump 4, and the pressure limiter 8 is dropped from the outlet of the overflow pipe 20 for returning it into the fuel tank 3, the fuel tank The stored fuel in 3 bubbles and bubbles are generated. At this time, if the outlet of the overflow pipe 20 is arranged in the vicinity of the suction port of the low-pressure fuel pipe 41 in the fuel tank 3, air such as bubbles is sucked together with fuel from the suction port of the low-pressure fuel pipe 41. Air such as bubbles is mixed into the fuel and flows into the fuel filter 6. Further, as shown in FIG. 1, the fuel supply path between the downstream side of the fuel filter 6 in the fuel flow direction from the filter element 61 and the upstream side of the fuel pumping chamber 31 of the supply pump 4 in the fuel flow direction. When the feed pump 5 is disposed therein, the pressure in the fuel supply path (cylindrical space 64, outlet 66, low-pressure fuel pipe 42) downstream of the filter element 61 of the fuel filter 6 in the fuel flow direction is fed. A negative pressure is generated by the suction of the pump 5, and bubbles are likely to be generated in the fuel, that is, air in the fuel is easily separated into large bubbles.

  Therefore, in this embodiment, a space having a large internal volume is formed in the upper portion of the fuel filter 6 in the figure (the top side of the fuel filter 6 in the vertical direction). This space is located above the outlet of the cylindrical space 64 in the figure, and further above the opening (inlet part) of the outlet 66 (that is, where air such as bubbles easily collects). Therefore, it functions as an air reservoir chamber 67 that temporarily stores air such as bubbles that have passed through the filter element 61. The air storage chamber 67 is provided between the outlet portion of the cylindrical space 64 and the opening portion of the outlet 66 so that the ceiling portion of the filter case 62 protrudes upward in the figure (top side in the vertical direction). It is formed by making it convex.

  Here, from the filter element 61 of the fuel filter 6 of the present embodiment to the discharge port (discharge port of the supply pump 4) 26 of the outlet pipe 56 from the downstream side in the fuel flow direction (exit portion of the cylindrical space 64). The fuel supply path includes a fuel suction path for sucking fuel from the outlet of the cylindrical space 64 of the fuel filter 6 to the suction side of the feed pump 5, and a solenoid valve 13 and a suction valve 30 from the discharge side of the feed pump 5. A fuel suction path for sucking low-pressure fuel into the fuel pressurization chamber 31 via the fuel, and a fuel discharge path 55 for pumping high-pressure fuel from the fuel pressurization chamber 31 to the discharge port 26 via the discharge valve 32. It consists of and. The fuel suction path includes a fuel suction path in the outlet 66, a fuel suction path in the low-pressure fuel pipe 42, a suction port 25 in the inlet pipe 43, a fuel introduction path 44, and the like. Further, the fuel suction path is constituted by a fuel lead-out path 45, a fuel suction path 54, and the like.

  As shown in FIGS. 1 and 5, the air vent mechanism 7 returns air such as bubbles temporarily stored in the air pool chamber 67 of the fuel filter 6 to the fuel tank 3 via the overflow pipe 20. The air vent pipe (air vent path, air recirculation path) 69 and the electromagnetic valve 14 for opening and closing the air vent pipe 69 are provided. The upstream end of the air vent pipe 69 in the air flow direction is connected to the ceiling portion of the air reservoir chamber 67 having a large internal volume, which is provided on the upper portion of the fuel filter 6 (the top side of the fuel filter 6 in the vertical direction).

  The electromagnetic valve 14 corresponds to an air vent control valve, and a ball valve (valve element) 72 that opens and closes a valve hole 71 provided on the upstream side of the air vent pipe 69 and drives the ball valve 72 in the valve opening direction. A solenoid coil 73, a stator core (not shown) and a moving core 74 that are magnetized when the solenoid coil 73 is energized, a spring 75 that biases the ball valve 72 in the valve closing direction, and a valve case that houses the ball valve 72 76. The stator core is provided with a suction portion that sucks the moving core 74.

  Further, the ball valve 72 operates in the axial direction integrally with the moving core 74 via the valve shaft 77. The ball valve 72 and the spring 75 are accommodated in a valve operating chamber 78 that communicates the valve hole 71 and the air reservoir 67. The valve working chamber 78 is formed inside a valve case 76 that also serves as a filter cover attached to the top side of the filter case 62 of the fuel filter 6. Further, the solenoid coil 73 functions as valve body driving means for driving the ball valve 72 and the valve shaft 77 in the valve opening direction. The spring 75 functions as a valve body urging means that urges the ball valve 72 and the valve shaft 77 in the valve closing direction.

  Here, a fuel pressure sensor 11 for detecting the pressure of the fuel in the fuel lead-out path 45 is provided in the fuel lead-out path 45 from the discharge side of the feed pump 5 to the inlet of the electromagnetic valve 13 as shown in FIG. is set up. Alternatively, as shown in FIG. 1, the fuel pressure sensor 11 that detects the pressure of the fuel in the fuel pressurization chamber 31 is installed in the fuel pressurization chamber 31 of the supply pump 4. The fuel pressure sensor 11 is electrically connected to the ECU 10 and outputs a detection signal (electric signal: for example, a voltage signal) corresponding to the detected pressure value to the ECU 10.

  On the other hand, the ECU 10 calculates the basic injection amount from the engine rotation speed detected by the rotation speed detection means such as a crank angle sensor and the accelerator opening detected by the engine load detection means such as the accelerator opening sensor. Next, a command injection amount is calculated by adding an injection amount correction amount in consideration of engine coolant, fuel temperature, and the like to the basic injection amount. Next, the command injection timing is calculated from the engine speed and the accelerator opening. Alternatively, the command injection timing is calculated from the engine speed and the command injection amount. Next, the energization time (command injection period) to the solenoid coil (not shown) of the solenoid valve 12 of the injector 2 is calculated from the command injection amount and the common rail pressure. From the command injection time to the end of the command injection period, fuel injection into the combustion chamber of each cylinder of the engine is performed by applying a pulsed injector drive current to the solenoid coil of the solenoid valve 12 of the injector 2. The

  Further, the ECU 10 calculates a target common rail pressure (target fuel pressure) based on the engine rotation speed and the command injection amount. Then, in order to achieve the target common rail pressure, the pump drive current applied to the solenoid coil of the solenoid valve 13 of the supply pump 4 is adjusted, and the fuel discharge amount discharged into the common rail 1 from the discharge port 26 of the supply pump 4 Is configured to control. Here, preferably, for the purpose of improving the control accuracy of the fuel injection amount, the fuel discharge amount is feedback-controlled so that the common rail pressure (actual fuel pressure) detected by the common rail pressure sensor substantially matches the target common rail pressure. It is desirable. More preferably, for the purpose of further improving the control accuracy of the fuel injection amount, PI (proportional integral) control is performed so that the common rail pressure (actual fuel pressure) detected by the common rail pressure sensor substantially matches the target common rail pressure. Alternatively, it is desirable to perform feedback control of the pump drive current applied to the solenoid coil of the solenoid valve 13 having a correlation with the fuel discharge amount by PID (proportional integral derivative) control. The pump drive current is preferably controlled by duty ratio (DUTY ratio) control.

  Further, the ECU 10 estimates an air mixing amount estimation means (air amount estimation) for estimating the amount of air mixed in the fuel (air mixing amount such as bubbles) according to the detection signal (pressure detection value) from the fuel pressure sensor 11. And the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is energized (ON) when the estimated air mixing amount estimated by the air mixing amount estimating unit is equal to or greater than a predetermined value (determination threshold). And an electromagnetic valve driving means. When the estimated air mixing amount is less than a predetermined value (determination threshold), energization to the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is stopped (OFF). Note that when the solenoid coil 73 of the solenoid valve 14 is once turned on, hysteresis may be provided to prevent hunting. That is, a difference is provided between a first predetermined value (determination threshold) for turning on the solenoid coil 73 and a second predetermined value (determination threshold) for turning off the solenoid coil 73. Alternatively, the solenoid coil 73 of the solenoid valve 14 may be forcibly turned off when a predetermined time has elapsed since the solenoid coil 73 of the solenoid valve 14 was turned on.

[Control Method of Example 1]
Next, a method for controlling the solenoid valve 14 of the air vent mechanism 7 of this embodiment will be briefly described with reference to FIGS. Here, FIG. 6 is a flowchart showing a method for controlling the solenoid valve of the air vent mechanism. The routine shown in FIG. 6 is executed at predetermined timings after the ignition switch is turned on (IG / ON). Further, when the ignition switch is turned off (IG · OFF), it is forcibly terminated.

  First, the fuel pressure is detected by the fuel pressure sensor 11 (pressure detection means, pressure pulsation detection means: step S1). Next, depending on the fuel pressure measured by the fuel pressure sensor 11, the fuel that is sucked into the suction side of the feed pump 5 from the suction port of the low-pressure fuel pipe 41, or the fuel pressurization of the supply pump 4 from the discharge side of the feed pump 5. An air mixing amount such as bubbles mixed in the low-pressure fuel sucked into the chamber 31 is estimated (air mixing amount estimating means: step S2). At this time, the air storage amount temporarily stored in the air storage chamber 67 of the fuel filter 6 through the filter element 61 of the fuel filter 6 from the suction port of the low-pressure fuel pipe 41 may be estimated.

Here, the fuel pressure in the fuel pressurizing chamber 31 of the supply pump 4 is determined by the plunger 24 reciprocatingly sliding in the sliding hole of the cylinder head 23 as the pump drive shaft 27 of the supply pump 4 rotates. Since the suction stroke for sucking the low-pressure fuel from the suction valve 30 into the fuel pressurization chamber 31 and the discharge stroke for discharging the high-pressure fuel boosted in the fuel pressurization chamber 31 toward the discharge valve 32 are repeated. This causes fuel pressure pulsation.
The fuel pressure on the discharge side of the feed pump 5 is adjusted so that the inner rotor 21 and the outer rotor 22 of the feed pump 5 rotate relative to each other as the pump drive shaft 27 of the supply pump 4 rotates, so In order to repeat the intake stroke for sucking fuel into the variable volume space (interdental space) 37 from the side and the discharge stroke for discharging low pressure fuel boosted in the variable volume space 37 from the discharge side to the electromagnetic valve 13, FIG. As shown in FIG. 7, fuel pressure pulsation occurs with time.
The fuel pressure in the fuel filter 6 also causes fuel pressure pulsation over time due to the suction operation of the feed pump 5.

In the present embodiment, the fuel pressure sensor 11 is used to measure the fuel pressure pulsation for the purpose of accurately estimating the amount of air mixed in such as air bubbles. As described above, the fuel pressure sensor 11 is connected to the supply pump 4. It is installed near the fuel pressurizing chamber 31 or on the discharge side of the feed pump 5.
However, when the fuel filter 6 is installed on the upstream side in the fuel flow direction from the suction side of the feed pump 5 as in the present embodiment, bubbles are generated when passing through the filter element 61 of the fuel filter 6. Since the fuel filter 6 is easily crushed, it is desirable to install the fuel pressure sensor 11 downstream of the filter element 61 of the fuel filter 6 in the fuel flow direction and upstream of the fuel pressurizing chamber 31 of the supply pump 4 in the fuel flow direction. . In particular, it is desirable to install the fuel pressure sensor 11 on the discharge side of the feed pump 5 where the bubbles are crushed and the fuel pressure pulsation easily occurs and the pressure in the fuel supply path varies from negative pressure to positive pressure.

  Here, the estimation method of the air mixing amount of bubbles and the like in this embodiment will be described. When air such as bubbles is mixed into the fuel, as shown in the graph of FIG. 7, the frequency of the fuel pressure pulsation generated on the discharge side of the feed pump 5 increases, or the amplitude of the fuel pressure pulsation increases. Therefore, by measuring the pressure pulsation of the fuel that changes over time from the pressure detection value detected by the fuel pressure sensor 11, the amount of air mixed in such as bubbles is estimated.

The graph of FIG. 7A shows the pressure pulsation of the fuel discharged from the discharge side of the feed pump 5 because the air mixing amount such as bubbles sucked into the feed pump 5 (volume variable space 37) is small. (Variation) represents a situation (pressure pulsation waveform of fuel in a normal state) smaller than a determination value (predetermined value). The pressure obtained by averaging the pressure pulsation of the fuel pressure corresponds to the pressure (predetermined pressure) on the discharge side of the feed pump 5.
Further, the graph of FIG. 7B shows a large amount of air mixed in such as bubbles sucked into the inside of the feed pump 5 (volume variable space 37), and the pressure pulsation of fuel discharged from the discharge side of the feed pump 5 ( This represents a situation (variation) greater than a judgment value (predetermined value) (pressure pulsation waveform of fuel when air such as bubbles is mixed (abnormal)). The pressure obtained by averaging the pressure pulsation of the fuel pressure corresponds to the pressure (predetermined pressure) on the discharge side of the feed pump 5.

  Here, as in this embodiment, when the fuel filter 6 is installed on the upstream side in the fuel flow direction with respect to the suction side of the feed pump 5, the upstream side in the fuel flow direction with respect to the suction side of the feed pump 5 ( Since a negative pressure is generated at the downstream side of the filter element 61 of the fuel filter 6 in the fuel flow direction, the negative pressure may be detected to estimate the amount of air mixed in such as bubbles. Further, the air mixing amount such as bubbles may be estimated from the fuel pressure, fuel temperature, and engine speed.

  Next, an air mixing amount such as bubbles mixed in fuel sucked into the suction side of the feed pump 5 from the suction port of the low-pressure fuel pipe 41 (negative pressure is generated by suction of the feed pump 5, and the filter element 61 of the fuel filter 6. It is determined whether or not the amount of bubbles generated in the fuel on the downstream side in the fuel flow direction is equal to or greater than a determination value (predetermined value: determination threshold) (step S3). Here, the air mixing amount of bubbles or the like being equal to or higher than the determination value refers to the case where the fuel pressure exceeds the high pressure side determination value or the fuel pressure falls below the low pressure side determination value. In addition, if the number of times the air mixing amount such as bubbles is equal to or more than the determination value is 2 or 3 times or more, if the air mixing amount such as bubbles is determined to be equal to or more than the determination value, The determination accuracy can be improved.

If the determination result in step S3 is NO, that is, if the air mixing amount such as bubbles is less than the determination value (predetermined value), energization to the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is stopped ( OFF) to close the solenoid valve 14 (step S4). Thus, when the energization to the solenoid coil 73 is stopped (OFF), the position of the ball valve 72 of the electromagnetic valve 14 is seated on the valve seat by the urging force of the spring 75 and the position is controlled to the initial position where the valve hole 71 is closed. Is done. In this initial position, the communication state between the air vent pipe 69 and the air reservoir 67 is interrupted.
Alternatively, when the solenoid coil 73 of the solenoid valve 14 is not energized, the OFF state of the solenoid valve 14 is maintained. Next, the common rail fuel injection system is normally operated (step S6). Thereafter, the routine of FIG. 5 is exited.

If the determination result in step S3 is YES, that is, if the amount of air mixed in such as bubbles is equal to or greater than a determination value (predetermined value), the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is energized. (ON) to open the solenoid valve 14 (step S7). As described above, when the solenoid coil 73 is energized (ON), the moving core 74 is attracted to the attracting portion of the stator core, so that the ball valve 72 of the solenoid valve 14 is resisted against the urging force of the spring 75. The position is controlled to a full lift position in which the valve hole 71 is opened away from the valve seat. At this full lift position, the air vent pipe 69 and the air reservoir chamber 67 communicate with each other, so that air such as air bubbles (with fuel) stored in the air reservoir chamber 67 of the fuel filter 6 flows into the valve operating chamber 78 → the valve hole. 71 → Air venting pipe 69 → Overflow pipe 20 is returned to the fuel tank 3.
Alternatively, when the solenoid coil 73 of the solenoid valve 14 is energized, the ON state of the solenoid valve 14 is maintained. Thereafter, the process proceeds to step S1.

[Operation of Example 1]
Next, the operation of the supply pump 4 used in the common rail fuel injection system according to this embodiment will be briefly described with reference to FIGS.

When the pump drive shaft 27 of the supply pump 4 is driven by the belt driven by the crankshaft of the engine and rotates, the inner rotor 21 and the outer rotor 22 of the feed pump 5 rotate relatively with the rotation of the pump drive shaft 27. Thus, the fuel stored in the fuel tank 3 is sucked from the suction port of the low pressure fuel pipe 41 and flows into the fuel filter 6 via the low pressure fuel pipe 41.
When the fuel flowing into the cylindrical space 64 from the inlet 65 of the filter case 62 passes through the filter element 61 installed in the cylindrical space 64, impurities contained in the fuel are removed. Then, the fuel that has been filtered and purified by the filter element 61 flows out from the outlet portion of the cylindrical space 64, and flows out from the fuel filter 6 through the air reservoir 67 and the outlet 66.

The fuel flowing out from the fuel filter 6 is introduced into the fuel introduction path 44 via the low pressure fuel pipe 42 and the suction port 25 and is sucked into the suction side of the feed pump 5. The fuel sucked into the variable volume space 37 formed between the inner rotor 21 and the outer rotor 22 from the suction side of the feed pump 5 is pressurized with a change in the internal volume of the variable volume space 37 and is predetermined. The fuel pressure is increased to a predetermined pressure and discharged from the discharge side of the feed pump 5.
The fuel discharged from the discharge side of the feed pump 5 is supplied to the inlet portion of the electromagnetic valve 13 via the fuel lead-out path 45. The fuel discharged from the discharge side of the feed pump 5 is also supplied into the accommodating chamber 49 by bypassing the electromagnetic valve 13 or via the electromagnetic valve 13 and the fuel outlet path 46.
The fuel supplied from the feed pump 5 bypassing the electromagnetic valve 13 or passing through the electromagnetic valve 13 into the storage chamber 49 is between the pump drive shaft 27 and the pump housing 29, and the two plungers 24. After lubricating each sliding part inside the housing of the supply pump 4 such as between the cam ring 34 and between the cam 33 and the cam ring 34, the oil is returned to the fuel tank 3 via the overflow pipe 20.

  Further, the cam 33 of the supply pump 4 rotates as the pump drive shaft 27 rotates. The cam ring 34 revolves along a predetermined circular path without rotating as the cam 33 rotates. As the cam ring 34 revolves, the cam ring 34 and the two plungers 24 slide, and the two plungers 24 reciprocate and slide on the sliding surfaces in the two cylinder heads 23 in the illustrated vertical direction. As the cam ring 34 revolves, the two plungers 24 are alternately lifted. In the state shown in FIGS. 2 to 4, the plunger 24 on one side (the upper side in the figure) is at the top dead center and the other side (the lower side in the figure). The plunger 24 is located at the bottom dead center.

As the cam ring 34 revolves, the plunger 24 on one side located at the top dead center descends downward in the figure, and the fuel pressure in the fuel pressurizing chamber 31 located on one side (the upper side in the figure) in FIGS. And the valve body of the intake valve 30 is opened by this fuel pressure. Then, by changing the opening area of the inlet port or the outlet port in accordance with the lift position of the spool valve of the electromagnetic valve 13, the fuel that has been metered so as to have the optimum value is passed through the fuel intake path 54 through the intake valve 30. The air is sucked into the fuel pressurizing chamber 31 via.
When the plunger 24 on one side reaches the bottom dead center and then starts to rise again toward the top dead center, the fuel pressure in the fuel pressurizing chamber 31 rises, and the valve of the intake valve 30 is increased by this fuel pressure. The body closes. When the fuel pressure in the fuel pressurizing chamber 31 further increases, the valve body of the discharge valve 32 is opened, and the high-pressure fuel boosted in the fuel pressurizing chamber 31 passes through the fuel discharge path 55 and the discharge port 26. The pressure is fed into the common rail 1.

On the other hand, the plunger 24 on the other side is also moved to the other side (lower side in the figure) in FIGS. 2 to 4 by reciprocatingly sliding between the top dead center and the bottom dead center in the same manner as the plunger 24 on the one side. The fuel is pressurized in the fuel pressurizing chamber 31. Then, the high-pressure fuel boosted in the fuel pressurizing chamber 31 is pressure-fed and supplied into the common rail 1 via the fuel discharge path 55 and the discharge port 26.
Thus, the supply pump 4 is configured such that the suction stroke and the pressure feed stroke are performed for two cycles per one rotation of the pump drive shaft 27. The high pressure fuel accumulated in the common rail 1 is injected and supplied into the combustion chamber of each cylinder of the engine at a predetermined timing by driving the electromagnetic valve 12 of the injector 2 at an arbitrary injection timing.

[Effect of Example 1]
As described above, in the common rail fuel injection system of the present embodiment, the inner rotor 21 and the outer rotor 22 of the feed pump 5 rotate relatively by operating the engine. Thus, the fuel stored in the fuel tank 3 is sucked from the suction port of the low pressure fuel pipe 41 and flows into the fuel filter 6 via the low pressure fuel pipe 41.
On the other hand, when air such as bubbles sucked from the suction port of the low-pressure fuel pipe 41 or air such as bubbles generated when passing through the filter element 61 of the fuel filter 6 flows into the fuel filter 6, It is gradually accumulated in the upper part (the air reservoir chamber 67 located on the upper side in the drawing from the outlet of the cylindrical space 64).
Based on the detection signal (pressure detection value) output from the fuel pressure sensor 11, the amount of air such as bubbles mixed in the fuel is estimated. When the estimated air mixing amount of air bubbles or the like (air mixing amount estimated value) is equal to or greater than a determination value (predetermined value), the electromagnetic valve 14 of the air vent mechanism 7 is opened. Therefore, when the solenoid valve 14 is opened, the air vent pipe 69 and the air reservoir chamber 67 communicate with each other, so that the valve operating chamber 78 → the valve hole 71 → the air vent pipe from the air reservoir chamber 67 provided in the upper part of the fuel filter 6. 69 → Air such as air bubbles is returned into the fuel tank 3 via the overflow pipe 20.

  Thereby, even when air such as bubbles generated by dropping excess fuel from the outlet of the overflow pipe 20 into the fuel tank 3 is sucked from the suction port of the low-pressure fuel pipe 41, or the filter element 61 of the fuel filter 6. The pressure in the fuel supply path (cylindrical space 64, outlet 66, low-pressure fuel pipe 42) on the downstream side in the fuel flow direction becomes negative pressure by the suction of the feed pump 5, and the air in the fuel is separated and bubbles or the like Even when the air is generated, the air such as bubbles is temporarily stored in the upper part of the fuel filter 6 (the air reservoir chamber 67), and then upstream of the fuel pressurizing chamber 31 of the supply pump 4 in the fuel flow direction. The fuel supply path, that is, the fuel supply path upstream in the fuel flow direction from the suction side of the feed pump 5 can be removed. .

  Accordingly, air such as bubbles mixed in the fuel sucked into the suction side of the feed pump 5 can be prevented from being sucked into the inside of the feed pump 5 (volume variable space 37). It is possible to prevent air such as bubbles from entering the low-pressure fuel discharged more. That is, in the intake stroke of the feed pump 5 in which the volume variable space 37 is enlarged, the inside of the feed pump 5 (volume variable space 37) from the fuel filter 6 via the low pressure fuel pipe 42, the intake port 25, and the fuel introduction path 44. In the intake stroke of the supply pump 4 in which air such as bubbles is not sucked into the air pump and the plunger 24 located at the top dead center is lowered, the fuel lead-out path 45, the electromagnetic valve 13, Air such as bubbles is not sucked into the fuel pressurization chamber 31 of the supply pump 4 via the fuel suction path 54 and the suction valve 30.

Therefore, the low-pressure fuel with the optimum intake amount that is metered by the electromagnetic valve 13 and that corresponds to the operating state of the engine can be sucked into the fuel pressurizing chamber 31 of the supply pump 4. The fuel discharge amount discharged from 26 is an optimum value. As a result, a sufficient amount of high-pressure fuel can be pumped and supplied into the common rail 1, and fuel pumping failure due to air mixing such as bubbles can be prevented. As a result, it is possible to prevent problems such as deterioration in engine startability, reduction in engine output, engine stall, and the like.
Further, since the fuel pressure accumulated in the common rail 1 (common rail pressure) can be optimized, the injection characteristic of the fuel injection amount injected and supplied from the injector 2 into the combustion chamber of each cylinder of the engine is determined from a preset control pattern. It is possible to prevent the change. Further, in order to prevent fuel pumping failure, it is possible to prevent fuel pumping failure without adopting a method of raising the fuel intake amount or fuel pumping amount by a certain amount. Deterioration of fuel consumption can be prevented.

[Configuration of Example 2]
8 and 9 show a second embodiment of the present invention, and FIG. 8 shows a fuel filter and an air vent mechanism.

  The fuel filter 6 of the present embodiment is installed on the upstream side in the fuel flow direction from the suction side of the feed pump 5 as in the first embodiment. As shown in FIG. 8, the fuel filter 6 includes a circular (or rectangular) porous membrane tube 91, a filter case 92 that accommodates the porous membrane tube 91, and the like. The porous membrane tube 91 is installed in an internal space 93 formed in the filter case 92. Impurities contained in the fuel sucked from the fuel tank 3 to the suction side of the feed pump 5 (hazardous substances: dust, Solid parts such as rust, sludge and moisture such as carbon and gum-like substances are removed by filtration or trapping, and it is a tubular part that does not allow fuel to permeate and allows only air such as bubbles to permeate. .

  An inlet 65 for introducing fuel from the fuel tank 3 into the internal space 93 of the filter case 92 via the low-pressure fuel pipe 41 is provided upstream of the porous membrane tube 91 in the fuel flow direction. It protrudes from the side wall surface of 92. Further, downstream of the porous membrane tube 91 in the fuel flow direction, the fuel filtered and purified by the porous membrane tube 91 is led to the suction port 25 of the supply pump 4 via the low-pressure fuel pipe 42. An outlet 66 is provided so as to protrude from the side wall surface of the filter case 92. In addition, on the top side of the fuel filter 6 in the top-and-bottom direction, that is, on the upper side in the figure of the internal space 93 of the filter case 92, an air reservoir chamber 67 that easily collects air such as bubbles and has a large internal volume is formed. .

  As shown in FIG. 8, the air vent mechanism 7 of the present embodiment passes air such as bubbles stored in an air reservoir chamber 67 provided in the upper part of the internal space 93 of the fuel filter 6 via the overflow pipe 20. An air vent pipe 69 for returning to the fuel tank 3 and an electric vacuum pump (vacuum device) 15 for sucking air such as bubbles stored in the air reservoir 67 into the air vent pipe 69 are provided. . The electromagnetic valve 14 described in the first embodiment may be installed in the air vent pipe 69.

[Control Method of Example 2]
Next, a method for controlling the solenoid valve 14 and the vacuum pump 15 of the air vent mechanism 7 of the present embodiment will be briefly described with reference to FIGS. Here, FIG. 9 is a flowchart showing a method of controlling the vacuum pump of the air vent mechanism. The routine shown in FIG. 9 is executed at predetermined timings after the ignition switch is turned on (IG / ON). Further, when the ignition switch is turned off (IG · OFF), it is forcibly terminated.

  Here, the same processes as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. That is, when the amount of air such as bubbles mixed in the fuel is less than the determination value (predetermined value), energization to the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is stopped (OFF) and the solenoid valve is turned off. 14 is closed, and the operation of the vacuum pump 15 of the air vent mechanism 7 is stopped (OFF) (step S5). Alternatively, when the vacuum pump 15 is not operating, the vacuum pump 15 is maintained in the OFF state. Next, the common rail fuel injection system is normally operated, and thereafter, the routine of FIG. 9 is exited.

  Also, the amount of air mixed in the fuel sucked into the suction side of the feed pump 5 from the suction port of the low pressure fuel pipe 41 (air pressure becomes negative due to the suction of the feed pump 5 and the porous membrane tube of the fuel filter 6 (Including the amount of bubbles generated in the fuel on the downstream side of the fuel flow direction from 91) is equal to or greater than a determination value (predetermined value), energization to the solenoid coil 73 of the solenoid valve 14 of the air vent mechanism 7 is performed. (ON) to open the electromagnetic valve 14 and further activate (ON) the vacuum pump 15 of the air vent mechanism 7 (step S8). As described above, when the vacuum pump 15 starts to operate, air such as bubbles stored in the air pool chamber 67 of the fuel filter 6 is sucked, and the fuel tank 3 passes through the air vent pipe 69 and the overflow pipe 20. Returned to Or when the vacuum pump 15 is operating, the ON state of the vacuum pump 15 is maintained. Thereafter, the process proceeds to step S1.

  In the case of the present embodiment, a porous membrane tube 91 that does not transmit fuel but can only transmit air such as air bubbles is employed as a filter element of the fuel filter 6. Since air such as bubbles stored in the air pool chamber 67 is forcibly sucked by the operation of the vacuum pump 15, only air such as bubbles mixed in the fuel can be surely removed. As a result, air such as bubbles is not sucked into the fuel pressurizing chamber 31 together with the fuel from the feed pump 5 in the suction stroke of the supply pump 4, and a sufficient amount of high-pressure fuel is pumped and supplied into the common rail 1. Therefore, it is possible to prevent problems such as poor fuel pumping and engine stall.

  Further, since the pressure inside the filter case 92 of the fuel filter 6 (in the air reservoir chamber 67) may be lower than the pressure in the overflow pipe 20 due to suction of the feed pump 5, the pressure inside the air reservoir chamber 67 is increased. In some cases, it is difficult to discharge the stored air such as bubbles, but the feed pump is interposed between the fuel filter 6 and the fuel pressurizing chamber 31 of the supply pump 4 by forcibly sucking the air by operating the vacuum pump 15. 5, even if the pressure inside the filter case 92 of the fuel filter 6 becomes negative due to the suction of the feed pump 5, the upstream side in the fuel flow direction from the suction side of the feed pump 5 (of the fuel filter 6 Upper part: Air such as bubbles can be reliably removed from the air reservoir 67).

  FIG. 10 shows the third embodiment of the present invention and is a diagram showing the overall configuration of the supply pump.

  The supply pump 4 of this embodiment is provided with a fuel pressure sensor 11 that outputs a detection signal (electric signal: for example, a voltage signal) corresponding to the detected pressure value to the ECU 10. In this embodiment, the fuel pressure sensor 11 is installed in the suction port 25 or the fuel introduction path 44 of the supply pump 4, and is located upstream of the feed pump 5 in the fuel flow direction (in the fuel introduction path 44. ) The fuel pressure is detected. The fuel pressure sensor 11 is installed in the fuel discharge path 55 or the discharge port 26 of the supply pump 4 to detect the fuel pressure downstream of the fuel pressurization chamber 31 of the supply pump 4 in the fuel flow direction. Also good.

  FIG. 11 shows Embodiment 4 of the present invention and is a diagram showing a main configuration of a common rail fuel injection system.

  In the common rail fuel injection system of the present embodiment, the fuel is mixed into the fuel sucked from the suction port of the low-pressure fuel pipe 41 to the suction side of the feed pump 5 based on the fuel pressure detected by the fuel pressure sensor 11. The amount of air mixed in such as air bubbles (including the amount of air bubbles generated in the fuel downstream of the filter element 61 of the fuel filter 6 in the fuel flow direction due to suction by the feed pump 5) is estimated. Then, the operation time of the fuel pressurizing mechanism 9 is controlled based on the estimated air mixing amount such as bubbles.

  The fuel pressurizing mechanism 9 is sucked into the suction side of the feed pump 5 through the fuel filter 6 from the suction port of the low pressure fuel pipe 16 for sucking the fuel in the fuel tank 3 from the suction port. An electric assist pump 17 for pressurizing the fuel to be pressurized, and an electromagnetic valve (electromagnetic switching valve) 18 for switching the fuel suction path from the fuel tank 3 to the fuel filter 6. The assist pump 17 is an in-tank low-pressure fuel pump installed upstream of the inlet portion of the fuel filter 6 in the fuel flow direction, particularly in the fuel tank 3. The assist pump 17 is rotationally driven by an electric motor (actuator) electrically connected to the ECU 10, sucks fuel stored in the fuel tank 3 from the suction port of the low-pressure fuel pipe 16, and pressurizes the fuel inside. And discharged to the suction side of the feed pump 5.

  The solenoid valve 18 includes a solenoid coil that generates a magnetomotive force when energized, a stator core and a moving core that are magnetized when the solenoid coil is energized, a valve body that operates integrally with the moving core, and a valve body that operates as a valve. And a spring urging to the side (first position side) seated on the seat. The stator core is provided with a suction portion that sucks the moving core. Further, the solenoid coil functions as a valve body driving means for driving the valve body to the side (second position side) away from the valve seat. Further, the spring functions as a valve body urging means that urges the valve body to the side (first position side) where the valve body is seated on the valve seat. When the energization of the solenoid coil is stopped (OFF), the position of the solenoid valve 18 is controlled to the first position (initial position) where the valve body is seated on the valve seat by the biasing force of the spring. In this first position, the communication state between the suction port of the low-pressure fuel pipe 16 and the suction side of the feed pump 5 (the inlet portion of the fuel filter 6) is cut off, and the suction port of the low-pressure fuel pipe 41 and the suction of the feed pump 5 are blocked. The side (inlet part of the fuel filter 6) is communicated.

  In addition, when the solenoid coil 18 is energized (ON), the moving core is attracted to the suction portion of the stator core, so that the valve body is separated from the valve seat against the biasing force of the spring. The position is controlled to the second position (full lift position). In this second position, the communication state between the suction port of the low-pressure fuel pipe 41 and the suction side of the feed pump 5 (the inlet portion of the fuel filter 6) is blocked, and the suction port of the low-pressure fuel pipe 16 and the suction of the feed pump 5 are blocked. The side (inlet part of the fuel filter 6) is communicated. Thereby, the electromagnetic valve 18 comprises the 2 position 3 way switching valve which switches a 1st position and a 2nd position by OFF and ON to a solenoid coil.

  In the ECU 10 of this embodiment, when air such as bubbles is mixed into the fuel, the frequency of the fuel pressure pulsation generated on the discharge side of the feed pump 5 increases, or the amplitude of the fuel pressure pulsation increases. By measuring the pressure pulsation of the fuel that changes over time from the pressure detection value detected by the fuel pressure sensor 11, the amount of air mixed in such as bubbles is estimated. When the air mixing amount such as bubbles is equal to or greater than a predetermined value (determination value), the solenoid coil of the solenoid valve 18 is turned on to switch to the second position, and the assist pump 17 is further turned on based on the air mixing amount such as bubbles. Controls pump efficiency (rotation speed of electric motor, fuel intake amount, fuel discharge amount) and operation duration. Specifically, the pump efficiency of the assist pump 17 is increased or the operation duration time of the assist pump 17 is lengthened as the amount of air such as bubbles increases.

  Here, when air such as bubbles is sucked from the suction port of the low-pressure fuel pipe 41, or the fuel supply path downstream of the fuel filter 6 in the fuel flow direction (cylindrical space 64, outlet 66, low-pressure fuel pipe 42). When the internal pressure becomes negative due to the suction of the feed pump 5 and the air in the fuel is separated and large bubbles are generated, air such as bubbles is sucked into the feed pump 5 (volume variable space 37) and further fed. Air flows out from the discharge side of the pump 5 and air such as bubbles is sucked into the fuel pressurization chamber 31 of the supply pump 4. Then, the amount of fuel sucked into the fuel pressurization chamber 31 of the supply pump 4 is substantially insufficient by the volume of air such as bubbles, and is supplied by pressure from the discharge port 26 of the supply pump 4 to the common rail side. The fuel discharge amount is substantially insufficient by the volume of air.

  Therefore, the assist pump 17 that is driven to rotate by the electric motor with respect to the feed pump 5 that is driven to rotate by the engine is used for the amount of air mixed in such as air bubbles mixed in the fuel sucked from the suction port of the low-pressure fuel pipe 41 (= By using it as an auxiliary pump that operates to compensate for the shortage of the amount of fuel sucked into the fuel pressurization chamber 31 of the supply pump 4, that is, as an auxiliary pump that assists the feed pump 5, Even when air such as bubbles is sucked into the (variable volume space 37), an appropriate amount of fuel can always be supplied into the fuel pressurizing chamber 31 of the supply pump 4.

  As a result, the fuel discharge amount that is pressure-fed and supplied from the discharge port 26 of the supply pump 4 to the common rail side is also an optimum fuel amount, and poor pumping of fuel due to mixing of air such as bubbles can be avoided. Further, the amount of air mixed in such as air bubbles mixed in the fuel sucked into the feed pump 5 (volume variable space 37) (discharged from the discharge side of the feed pump 5 and into the fuel pressurizing chamber 31 of the supply pump 4). As the amount of air mixed in such as air bubbles increases, the pump efficiency of the assist pump 17 is increased, or the operation duration time of the assist pump 17 increases as the amount of air mixed in such as air bubbles increases. By making the length longer, it is possible to suppress deterioration in fuel consumption due to excessive pumping of the assist pump 17 while avoiding poor pumping of fuel due to mixing of air such as bubbles.

[Modification]
In the present embodiment, the example in which the high-pressure fuel pump of the present invention is applied to a supply pump (fuel injection pump) 4 used in a common rail fuel injection system (accumulation fuel injection device) has been described. The present invention may be applied to a distribution type fuel injection pump or a row type fuel injection pump used in a fuel injection device for an internal combustion engine. The number of pump elements, that is, the number of plungers 24 may be one or three or more, and the number is arbitrary.

  In this embodiment, the high-pressure fuel pump of the present invention is a type that controls the fuel pumping amount or the fuel discharging amount of all pumping systems (pump elements) by metering the amount of fuel sucked by one solenoid valve 13. Although the example applied to the (pump metering type) supply pump 4 has been described, the high-pressure fuel pump according to the present invention controls a plurality of pumps by metering the fuel suction amount with a plurality of suction metering valves. You may apply to the supply pump of the type which controls the fuel pumping amount or fuel discharge amount of a system | strain (pump element).

  In the present embodiment, a feed pump (low pressure supply pump unit) 5 as a low pressure fuel pump and a pump element (high pressure supply pump unit) as a high pressure fuel pump are integrated with a supply pump (fuel injection pump) 4. Although assembled, the feed pump (low pressure fuel pump, low pressure supply pump) and the fuel injection pump (high pressure fuel pump, high pressure supply pump) may be separated and connected via a low pressure fuel pipe. In this case, the inlet portion of the electromagnetic valve 13 or the valve hole of the intake valve 30 on the downstream side in the fuel flow direction from the discharge side of the feed pump 5 becomes the intake port of the fuel injection pump.

  In the present embodiment, the fuel filter 6 is installed in the fuel supply path on the upstream side in the fuel flow direction from the suction side of the feed pump 5, but the downstream side in the fuel flow direction and the supply side from the discharge side of the feed pump 5. The fuel filter 6 may be installed in the fuel supply path between the fuel pressurizing chamber 31 of the pump 4 and the upstream side in the fuel flow direction. In the present embodiment, the fuel pressure sensor 11 is installed in the fuel pressure feed path from the outlet of the filter element 61 of the fuel filter 6 to the discharge port 26 of the supply pump 4. The fuel pressure sensor 11 may be installed in the fuel pressure feed path from the discharge side to the inlet or outlet of the solenoid valve 13 of the supply pump 4, the intake valve 30, or the fuel pressurizing chamber 31.

  In the present embodiment, an air reservoir chamber 67 having a large internal volume is provided at the upstream end of the air vent pipe 69 of the air vent mechanism 7 in the air flow direction at the upper part of the fuel filter 6 (the top side in the vertical direction of the fuel filter 6). The air reservoir chamber is provided above the low-pressure fuel pipe 42 (the top side of the low-pressure fuel pipe 42 in the vertical direction), and the air vent pipe (air vent path, air recirculation path) of the air vent mechanism 7 is provided. The upstream end of the air flow direction 69 may be connected to the ceiling of the air reservoir chamber. Further, an air reservoir chamber is provided above the supply pump 4 or the feed pump 5 (the top side of the supply pump 4 in the vertical direction), and the upstream end in the air flow direction of the air vent pipe 69 of the air vent mechanism 7 is connected to the air reservoir chamber. It may be connected to the ceiling part.

  In this embodiment, the discharge pressure of the feed pump 5 is a predetermined fuel pressure between the discharge side and the suction side of the feed pump 5 (between the fuel recirculation paths 52 and 53 communicating with the fuel outlet path 45 of the feed pump 5). A regulating valve (pressure regulating valve) 51 is installed to prevent the pressure from exceeding the value. The valve body of the regulator valve 51 is lifted by the discharge pressure of the feed pump 5 (the fuel pressure in the fuel lead-out path 45 and the fuel recirculation paths 52 and 53), and the fuel is recirculated to the suction side of the feed pump 5. Since the pressure in the clearance (opening) formed between the valve body and the valve seat becomes a negative pressure, bubbles may be generated in the fuel. Therefore, an air reservoir chamber is provided that communicates with the fuel supply path between the downstream side in the fuel flow direction from the discharge side of the feed pump 5 and the upstream side in the fuel flow direction from the fuel pressurization chamber 31 of the supply pump 4. Then, the upstream end in the air flow direction of the air vent pipe (air vent path, air recirculation path) 69 of the air vent mechanism 7 may be connected to the ceiling portion of the air reservoir chamber.

  In this embodiment, by measuring the pressure pulsation of the fuel that changes with time from the pressure detection value detected by the fuel pressure sensor 11, the low pressure fuel that is sucked into the fuel pressurization chamber 31 of the supply pump 4 is measured. The amount of air contamination such as air bubbles, or the amount of air contamination such as bubbles in the fuel sucked into the feed pump 5 is estimated. The air mixing ratio may be estimated.

It is the schematic diagram which showed the main structures of the common rail type fuel injection system (Example 1). 1 is a cross-sectional view showing an overall configuration of a common rail fuel injection system (Example 1). It is sectional drawing which showed the whole structure of the supply pump (Example 1). FIG. 4 is a sectional view taken along line AA in FIG. 3 (Example 1). It is the schematic which showed the fuel filter and the air vent mechanism (Example 1). (Example 1) which was the flowchart which showed the control method of the solenoid valve of an air vent mechanism. (A) is the graph which showed the pressure pulsation waveform of the fuel at the time of normal, (b) is the graph which showed the pressure pulsation waveform of the fuel at the time of air mixing, such as a bubble (Example 1). (Example 2) which is the schematic which showed the fuel filter and the air vent mechanism. (Example 2) which showed the control method of the vacuum pump of an air vent mechanism. It is sectional drawing which showed the whole structure of the supply pump (Example 3). (Example 4) which is the schematic diagram which showed the main structures of the common rail type fuel injection system.

Explanation of symbols

1 common rail 2 injector (fuel injection valve for internal combustion engine, electromagnetic fuel injection valve)
3 Fuel tank 4 Supply pump (high pressure fuel pump, fuel injection pump)
5 Feed pump (low pressure fuel pump)
6 Fuel filter 7 Air venting mechanism 9 Fuel pressurizing mechanism 10 ECU (pressure detecting means, pressure pulsation detecting means, air mixing amount estimating means)
11 Fuel pressure sensor (pressure detection means)
12 Injector solenoid valve (actuator)
13 Solenoid valve of supply pump (electromagnetic suction metering valve)
14 Solenoid valve for air vent mechanism (air vent control valve)
15 Vacuum pump with air vent mechanism (vacuum device)
16 Low pressure fuel piping of fuel pressurization mechanism (fuel supply path, fuel suction path)
17 Assist pump for fuel pressurization mechanism (electric pump)
18 Solenoid valve of the fuel pressurization mechanism (electromagnetic switching valve)
20 Overflow piping 21 Inner rotor of feed pump 22 Outer rotor of feed pump 23 Cylinder head (cylinder) of supply pump (pump element)
24 Plunger of supply pump (pump element) 31 Fuel pressurizing chamber 41 Low pressure fuel piping (fuel supply path, fuel suction path)
42 Low pressure fuel piping (fuel supply path, fuel suction path)
67 Fuel filter air reservoir (upper part of fuel filter)
69 Air vent piping (air vent path, air recirculation path) of air vent mechanism

Claims (11)

(A) a low-pressure fuel pump that sucks fuel stored in the fuel tank from a suction port of a low-pressure fuel pipe, pressurizes the fuel, and discharges the fuel;
(B) A pressurizing chamber for pressurizing and increasing the pressure of the low-pressure fuel supplied from the discharge side of the low-pressure fuel pump, and a discharge port for discharging the high-pressure fuel boosted in the pressurizing chamber to the fuel injection valve side of the internal combustion engine A high-pressure fuel pump having
(C) A fuel supply path for supplying the fuel sucked from the suction port of the low-pressure fuel pipe to the discharge port of the high-pressure fuel pump through the inside of the low-pressure fuel pump and the pressurizing chamber of the high-pressure fuel pump When,
(D) a pressure detecting means for detecting the fuel pressure in the fuel supply path, and a control device having an air mixing amount estimating means for estimating the air mixing amount mixed in the fuel by the pressure detection value of the pressure detecting means. A fuel supply device for an internal combustion engine. The fuel supply device for an internal combustion engine according to claim 1,
An air vent mechanism for removing air mixed in the fuel supplied into the pressurized chamber of the high-pressure fuel pump from the fuel supply path upstream of the pressurized chamber of the high-pressure fuel pump in the fuel flow direction;
The fuel supply device for an internal combustion engine, wherein the control device operates the air venting mechanism based on an estimated air mixing amount value of the air mixing amount estimating means. The fuel supply device for an internal combustion engine according to claim 2,
The air vent mechanism removes air mixed in the fuel supplied to the pressurized chamber of the high-pressure fuel pump from the fuel supply path upstream of the pressurized chamber of the high-pressure fuel pump in the fuel flow direction. A fuel supply device for an internal combustion engine, comprising an air vent pipe. The fuel supply device for an internal combustion engine according to claim 3,
An internal combustion engine fuel supply device, wherein an upstream end of the air vent pipe in the air flow direction is connected to a space provided upstream of the pressurizing chamber of the high pressure fuel pump in the fuel flow direction. The fuel supply device for an internal combustion engine according to claim 3 or 4,
A fuel filter that is installed upstream of the pressurizing chamber of the high-pressure fuel pump in the fuel flow direction and filters or traps impurities contained in the fuel sucked from the suction port of the low-pressure fuel pipe;
The fuel supply device for an internal combustion engine, wherein an upstream end of the air vent pipe in an air flow direction is connected to a space provided in an upper portion of the fuel filter. The fuel supply device for an internal combustion engine according to any one of claims 3 to 5,
The air vent mechanism has an air vent control valve that opens and closes an air vent path in the air vent pipe;
The fuel supply device for an internal combustion engine, wherein the control device opens the air vent control valve when an estimated value of air mixing amount of the air mixing amount estimating means is a predetermined value or more. The fuel supply device for an internal combustion engine according to any one of claims 3 to 6,
The air vent mechanism has a vacuum device that sucks air mixed in the fuel supplied into the pressurized chamber of the high pressure fuel pump into an air vent path in the air vent pipe,
The said control apparatus operates the said vacuum apparatus, when the estimated air mixing amount value of the said air mixing amount estimation means is more than predetermined value, The fuel supply apparatus for internal combustion engines characterized by the above-mentioned. The fuel supply device for an internal combustion engine according to any one of claims 1 to 7,
A fuel pressurizing mechanism for pressurizing the fuel supplied into the pressurizing chamber of the high-pressure fuel pump;
The fuel supply device for an internal combustion engine, wherein the control device operates the fuel pressurizing mechanism based on an estimated air mixing amount value of the air mixing amount estimating means. The fuel supply device for an internal combustion engine according to claim 8,
The fuel pressurizing mechanism has an electric pump installed on the upstream side in the fuel flow direction from the suction side of the low-pressure fuel pump,
The fuel supply device for an internal combustion engine, wherein the control device controls the pump efficiency of the electric pump based on an estimated amount of air contamination of the air contamination amount estimation means. The fuel supply device for an internal combustion engine according to any one of claims 1 to 9,
The pressure detecting means includes a fuel pressure sensor for detecting a fuel pressure in a suction side or a discharge side of the low-pressure fuel pump, or a pressurizing chamber or a discharge port of the high-pressure fuel pump;
The fuel supply device for an internal combustion engine, wherein the fuel pressure sensor is installed in the low pressure fuel pump or the high pressure fuel pump. The fuel supply device for an internal combustion engine according to any one of claims 1 to 10,
The low-pressure fuel pump has an inner rotor and an outer rotor, and by changing the interdental volume between the inner rotor and the outer rotor, the normal-pressure fuel in the fuel tank is pumped up and the low-pressure fuel is discharged to the high-pressure fuel pump. A feed pump,
The high-pressure fuel pump has a cylinder and a plunger, and by reciprocatingly sliding the plunger in the cylinder, the low-pressure fuel discharged from the discharge side of the feed pump is sucked into the pressurizing chamber, and the high-pressure fuel pump Is a supply pump that discharges to the fuel injection valve side of the internal combustion engine,
The fuel supply device for an internal combustion engine, wherein the feed pump is integrally assembled with the supply pump.

Images