JP2008202578A - High pressure fuel pump for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure fuel pump for an internal combustion engine, capable of enhancing marketability, and improving energy efficiency. <P>SOLUTION: The high pressure fuel pump 103 pressurizing fuel in a pressurizing chamber 132 and press-sending that to a high pressure fuel passage 105 side, comprises a plunger 131 reciprocating in a forward/backward moving direction according to rotations of a cam 321, a check valve 137 supplying the fuel from a low pressure fuel pipe 104 to the pressurizing chamber when pressure in the pressurizing chamber becomes not more than predetermined pressure, a check valve 151 press-sending the fuel from the pressurizing chamber to the high pressure fuel passage side when the pressure in the pressurizing chamber becomes not less than the predetermined pressure, an upper plunger 133 grounding so as to separate in the forward/backward moving direction to a tip end of the plunger in the pressurizing chamber and reciprocating in the forward/backward moving direction with the plunger, a plate 135 regulating a position in a leaving direction of the upper plunger energized in the leaving direction, and a plate driving means moving the plate in the forward/backward moving direction to position at a required position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-pressure fuel pump provided in an internal combustion engine such as, for example, an in-cylinder direct injection engine, and more particularly to measures for improving energy efficiency while suppressing the generation of abnormal noise.

  2. Description of the Related Art Conventionally, in an engine where high pressure is required for fuel supplied to an injector, such as an in-cylinder direct injection engine, the fuel sent from the fuel tank is pressurized with a high-pressure fuel pump and directed to the injector. To supply.

  Specifically, as a configuration of a fuel supply system in this type of engine, as disclosed in the following Patent Document 1, a feed pump that feeds fuel from a fuel tank, and a high pressure that pressurizes the fuel fed by the feed pump A fuel pump is provided. The fuel pressurized by the high-pressure fuel pump is discharged and stored in a delivery pipe to which a plurality of injectors are connected. As a result, the high-pressure fuel stored in the delivery pipe is injected from the opened injector toward the combustion chamber as the injector opens.

  The high-pressure fuel pump in this type of engine includes a plunger that reciprocates in the forward / backward direction in the cylinder based on the rotation of a cam attached to the exhaust camshaft, and a pressure chamber defined by the cylinder and the plunger. ing. The pressurizing chamber is connected to the feed pump through a low-pressure fuel passage and is connected to a delivery pipe through a high-pressure fuel passage. An injector is connected to the delivery pipe.

Further, the high-pressure fuel pump is provided with an electromagnetic spill valve that communicates and blocks between the low-pressure fuel passage and the pressurizing chamber. This electromagnetic spill valve includes an electromagnetic solenoid, and opens and closes by controlling the voltage applied to the electromagnetic solenoid. When the energization of the electromagnetic solenoid is stopped, the electromagnetic spill valve is opened by the biasing force of the coil spring, and the low pressure fuel passage and the pressurizing chamber are in communication with each other. In this state, when the plunger moves out in the direction in which the volume of the pressurizing chamber increases (during the suction stroke), the fuel sent from the feed pump is sucked into the pressurizing chamber through the low pressure fuel passage. The On the other hand, when the plunger moves forward in the direction in which the volume of the pressurizing chamber contracts (during the pumping stroke), the electromagnetic spill valve is closed against the urging force of the coil spring by energizing the electromagnetic solenoid. As a result, the low pressure fuel passage and the pressurizing chamber are disconnected, and fuel in the pressurizing chamber is discharged toward the high pressure fuel passage and the delivery pipe. The fuel discharge amount in the high-pressure fuel pump is adjusted by controlling the closing start timing of the electromagnetic spill valve and adjusting the closing period of the electromagnetic spill valve during the pumping stroke.
JP 2001-289099 A

  However, in the above-mentioned conventional one, when the gap between the low pressure fuel passage and the pressurizing chamber is cut off, the electromagnetic spill valve is closed by the applied voltage to the electromagnetic solenoid and is seated on the seat. Therefore, an impact is generated when the electromagnetic spill valve is seated on the seat, and this impact is transmitted to the outside as an abnormal noise. Since the electromagnetic spill valve is opened and closed every time the plunger reciprocates, abnormal noise generated by an impact when the electromagnetic spill valve is closed and seated on the seat frequently occurs, thereby improving the merchantability. It was a problem.

  Further, since the fuel in the pressurizing chamber is pressurized every time the plunger reciprocates in the forward / backward direction, when the fuel in the pressurizing chamber is not discharged to the high pressure fuel passage side, the electromagnetic spill valve is opened to open the pressurizing chamber. It is necessary to reversely flow the fuel to the low pressure fuel passage side. For this reason, the waste of reflowing the fuel pressurized in the pressurizing chamber back to the low-pressure fuel passage is caused, resulting in poor energy efficiency.

  The present invention has been made in view of such a point, and the object of the present invention is to prevent frequent occurrence of abnormal noise due to an impact at the time of closing operation of the electromagnetic spill valve and to enhance the commercial value. Another object of the present invention is to provide a high-pressure fuel pump for an internal combustion engine that can improve energy efficiency by eliminating useless backflow of fuel pressurized in a pressurizing chamber to the low-pressure fuel passage side.

  In order to achieve the above object, the solution provided by the present invention is to pressurize the fuel supplied from the fuel tank through the low pressure fuel pipe in the pressurizing chamber and feed it to the fuel injection system of the internal combustion engine. A high-pressure fuel pump for an internal combustion engine is assumed. A plunger that adjusts the pressure in the pressurizing chamber by reciprocating in the advancing and retreating direction based on the rotation of the cam, and the low pressure fuel pipe to the pressurizing chamber when the pressure in the pressurizing chamber falls below a predetermined pressure. Fuel supply means for enabling the supply of fuel, and fuel pumping means for allowing the fuel to be pumped from the pressurizing chamber to the fuel injection system when the pressure in the pressurizing chamber exceeds a predetermined pressure. Prepare. Further, the upper plunger is grounded so as to be separable in the advancing and retracting direction with respect to the tip of the plunger in the pressurizing chamber, and the upper plunger reciprocating in the advancing and retracting direction together with the plunger, and urged in a direction to ground the upper plunger to the tip of the plunger. A biasing means, a plate provided so as to be able to reciprocate in the advancing and retreating direction of the upper plunger, and regulating the position of the upper plunger in the retracting direction against the biasing force of the biasing means, and the plate reciprocatingly moving Plate driving means for positioning at a desired position.

  Due to this specific matter, the upper plunger urged in the direction of grounding with respect to the tip of the plunger by the urging means is brought into contact with the plunger while being grounded to the tip of the plunger that reciprocates in the forward / backward direction in the cylinder based on the rotation of the cam. Move back and forth in the forward and backward direction. At this time, since the upper plunger moves in the forward / backward direction together with the plunger, even if the plunger moves in the forward / backward direction, the volume of the pressurizing chamber does not change, and neither fuel is sucked nor discharged.

  When the plunger retreats, the position of the upper plunger in the retreat direction is regulated against the urging force of the urging means by the plate that reciprocates in the advancing / retreating direction of the plunger. To be separated. At this time, by restricting the position of the upper plunger in the retracting direction, only the plunger moves in the retracting direction in the direction of increasing the volume of the pressurizing chamber (during the suction stroke), and the fuel delivered from the feed pump is low pressure The air is sucked into the pressurized chamber through the fuel passage.

  On the other hand, if only the plunger moves in the advance direction in the direction in which the volume of the pressurizing chamber contracts (during the pumping stroke) in a state where the position of the upper plunger in the retracting direction is restricted, the fuel in the pressurizing chamber It is discharged toward the delivery pipe. At this time, the fuel discharge amount in the high-pressure fuel pump is adjusted by adjusting the position of the upper plunger that is regulated by the plate in the retracting direction.

  As described above, the fuel discharge amount is adjusted by adjusting the position of the upper plunger that is regulated by the plate in the retracting direction. Therefore, the fuel discharge amount is adjusted by adjusting the valve closing period of the electromagnetic spill valve during the pumping stroke. There is no need. For this reason, the electromagnetic spill valve is not required, and the shock generated when the electromagnetic spill valve is closed and seated on the seat is not transmitted to the outside as abnormal noise. This prevents frequent noise from being generated due to an impact during the closing operation of the electromagnetic spill valve that occurs each time the plunger reciprocates, thereby improving the merchantability.

  In addition, while the position of the upper plunger in the retracting direction is regulated by the plate, the fuel is absorbed into the pressurizing chamber by moving only the plunger in the direction in which the volume of the pressurizing chamber increases, while the pressurizing chamber Since the fuel in the pressurizing chamber is pressurized by moving only the plunger in the direction in which the volume of the fuel is contracted, the fuel discharge amount is adjusted based on the position of the upper plunger that is regulated by the plate in the retracting direction. become. For this reason, the pressure chamber is changed to the low pressure fuel passage when the fuel in the pressure chamber is not discharged to the high pressure fuel passage side, as in the case where the fuel in the pressurization chamber is pressurized each time the plunger reciprocates in the forward / backward direction. There is no need to open it. This eliminates the need for the fuel in the pressurizing chamber to flow back to the low pressure fuel passage, eliminates the waste of the fuel pressurized in the pressurizing chamber back to the low pressure fuel passage, and increases energy efficiency. Become.

  In order to achieve the above object, another solution provided by the present invention is to pressurize the fuel supplied from the fuel tank via the low-pressure fuel pipe in the pressurizing chamber and pump it to the fuel injection system of the internal combustion engine. Similarly, the high-pressure fuel pump of the internal combustion engine configured as described above is assumed. Furthermore, a plunger that adjusts the pressure in the pressurizing chamber by reciprocating in the advancing and retreating direction based on the rotation of the cam, and when the pressure in the pressurizing chamber falls below a predetermined pressure, the low pressure fuel pipe is moved to the pressurizing chamber. Fuel supply means for enabling the supply of fuel, and fuel pumping means for allowing the fuel to be pumped from the pressurizing chamber to the fuel injection system when the pressure in the pressurizing chamber exceeds a predetermined pressure. Prepare similarly. An upper plunger that is separable in the advancing and retreating direction with respect to the plunger tip in the pressurizing chamber and reciprocates in the advance and retreat direction together with the plunger, and urged in a direction that separates the upper plunger from the tip of the plunger. Urging means for reciprocating in the forward and backward direction of the upper plunger, and reciprocating together with the plunger in a state where the upper plunger is in contact with the urging force of the urging means and is in contact with the tip of the plunger. The plate to be moved back and forth, and the plate is moved to a desired position so that the position of the upper plunger in the advancing direction is restricted against the biasing force of the biasing means when the plunger moves in the retracting direction. And plate driving means for positioning.

  Due to this specific matter, the upper plunger biased in the direction away from the tip of the plunger by the biasing means is biased by the plate that moves in the forward / backward direction together with the plunger according to the reciprocating movement of the plunger in the forward / backward direction. It reciprocates in the advancing and retreating direction in a state where it is in contact with the tip of the plunger against the biasing force of At this time, since the upper plunger moves in the forward / backward direction together with the plunger, even if the plunger moves in the forward / backward direction, the volume of the pressurizing chamber does not change, and neither fuel is sucked nor discharged.

  When the plunger moves in the retracting direction (during the intake stroke), when the plate is positioned at a desired position by the plate driving means, the upper plunger is urged in a direction away from the tip of the plunger by the urging means. The position of the direction is restricted, and the upper plunger is separated from the tip of the plunger. At this time, by restricting the position of the upper plunger in the advance direction, only the plunger moves in the retreat direction in the direction in which the volume of the pressurizing chamber increases (during the intake stroke), and the fuel sent from the feed pump is low pressure The air is sucked into the pressurized chamber through the fuel passage.

  On the other hand, if the position of the upper plunger in the advance direction is regulated and the plunger moves in the advance direction in the direction in which the volume of the pressurization chamber contracts (during the pumping stroke), the fuel in the pressurization chamber is transferred to the high-pressure fuel passage and the delivery. It is discharged toward the pipe. At this time, the fuel discharge amount in the high-pressure fuel pump is adjusted by adjusting the position of the upper plunger that is regulated by the plate in the advancing direction.

  In this way, the fuel discharge amount is adjusted by adjusting the position of the upper plunger, which is regulated by the plate, in the advancing direction. Therefore, the fuel discharge amount is adjusted by adjusting the valve closing period of the electromagnetic spill valve during the pumping stroke. There is no need. For this reason, the electromagnetic spill valve is not required, and the shock generated when the electromagnetic spill valve is closed and seated on the seat is not transmitted to the outside as abnormal noise. This prevents frequent noise from being generated due to an impact during the closing operation of the electromagnetic spill valve that occurs each time the plunger reciprocates, thereby improving the merchantability.

  In addition, while the position of the upper plunger in the advancing direction is regulated by the plate, the fuel is absorbed into the pressurizing chamber by moving only the plunger in the direction in which the volume of the pressurizing chamber increases, while the pressurizing chamber Since the fuel in the pressurizing chamber is pressurized by moving only the plunger in the direction in which the volume of the cylinder contracts, the fuel discharge amount is adjusted based on the position in the advance direction of the upper plunger regulated by the plate become. For this reason, the pressure chamber is changed to the low pressure fuel passage when the fuel in the pressure chamber is not discharged to the high pressure fuel passage side, as in the case where the fuel in the pressurization chamber is pressurized each time the plunger reciprocates in the forward / backward direction. There is no need to open it. This eliminates the need for the fuel in the pressurizing chamber to flow back to the low pressure fuel passage, eliminates the waste of the fuel pressurized in the pressurizing chamber back to the low pressure fuel passage, and increases energy efficiency. Become.

  In short, the upper plunger is separated from the tip of the plunger by restricting the position of the upper plunger in the retracting direction or the advancing direction by the plate, and only the plunger is retracted to move the fuel into the pressurized chamber from the low pressure fuel passage side. While inhaling, only the plunger is moved forward to discharge the fuel in the pressurized chamber to the high-pressure fuel passage side, and by adjusting the fuel discharge amount based on the position of the upper plunger at the time of withdrawal or advancement, The abolition of the fuel discharge amount by adjusting the closing period of the electromagnetic spill valve during the pumping stroke will be abolished, and frequent noise generation due to impacts during the closing operation of the electromagnetic spill valve will be prevented, thereby improving the merchantability. it can. Moreover, there is no need to open the pressurization chamber to the low pressure fuel pipe when the fuel in the pressurization chamber is not discharged to the high pressure fuel passage. It can be eliminated and energy efficiency can be increased.

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

  In the first embodiment, a case where the present invention is applied to an in-cylinder direct injection multi-cylinder (for example, four-cylinder) gasoline engine mounted on an automobile will be described.

  FIG. 1 shows a schematic configuration of an engine (internal combustion engine) according to the first embodiment. As shown in FIG. 1, the engine 1 includes a piston 11 that defines a combustion chamber 10 and a crankshaft 13 that is an output shaft. The piston 11 is connected to the crankshaft 13 via the connecting rod 12, and the reciprocating motion of the piston 11 is converted into the rotational motion of the crankshaft 13 by the connecting rod 12.

  A signal rotor 14 having a plurality of protrusions 14a, 14a,... Is attached to the crankshaft 13 on the outer peripheral surface. A crank position sensor 15 is disposed in the vicinity of the signal rotor 14. The crank position sensor 15 outputs a pulse signal corresponding to the protrusion 14 a of the signal rotor 14 when the crankshaft 13 rotates.

  An intake passage 2 and an exhaust passage 3 are connected to the combustion chamber 10 of the engine 1. An intake valve 21 is provided between the intake passage 2 and the combustion chamber 10, and the intake passage 2 and the combustion chamber 10 are communicated or blocked by opening and closing the intake valve 21. An exhaust valve 31 is provided between the exhaust passage 3 and the combustion chamber 10, and the exhaust passage 3 and the combustion chamber 10 are communicated or blocked by opening and closing the exhaust valve 31. The opening / closing drive of the intake valve 21 and the exhaust valve 31 is performed by each rotation of the intake camshaft 22 and the exhaust camshaft 32 to which the rotation of the crankshaft 13 is transmitted.

  The intake camshaft 22 has a protrusion 22a. A cam position sensor 23 is disposed in the vicinity of the intake camshaft 22. The cam position sensor 23 outputs a detection signal each time the projection 22 a passes near the cam position sensor 23 as the intake camshaft 22 rotates.

  A throttle valve 24 for adjusting the intake air amount of the engine 1 is disposed in the upstream portion of the intake passage 2. The throttle valve 24 is driven by a throttle motor 25. The opening degree of the throttle valve 24 is adjusted by driving and controlling the throttle motor 25 in accordance with the depression operation of an accelerator pedal 26 provided in the interior of the automobile. Note that the amount of depression of the accelerator pedal 26 (accelerator depression amount) is detected by an accelerator position sensor 27. Further, in the intake passage 2, a vacuum sensor 28 for detecting the pressure (intake pressure) in the intake passage 2 is disposed downstream of the throttle valve 24.

  The engine 1 is provided with a fuel injection valve (injector) 4 for directly injecting fuel into the combustion chamber 10 for each cylinder. The fuel injection valve 4 for each cylinder is supplied with high-pressure fuel by a fuel supply device 100 described later, and the fuel is directly injected into the combustion chamber 10 from each fuel injection valve 4, thereby allowing air in the combustion chamber 10. Is formed in the combustion chamber 10 as the spark plug 29 is ignited. The combustion of the air-fuel mixture in the combustion chamber 10 causes the piston 11 to reciprocate and the crankshaft 13 to rotate.

  Next, the fuel injection control device will be described with reference to FIG. FIG. 2 is a block diagram showing a control system of the fuel injection control device.

  As shown in FIG. 2, the fuel injection control device includes an ECU (electronic control unit) 5 for controlling the operating state of the engine 1. The ECU 5 includes a CPU 51, a ROM 52, a RAM 53, a backup RAM 54, and the like.

  The ROM 52 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 51 executes arithmetic processing based on various control programs and maps stored in the ROM 52.

  The RAM 53 is a memory that temporarily stores calculation results of the CPU 51, data input from each sensor, and the like. The backup RAM 54 is a non-volatile memory that stores data to be saved when the engine 1 is stopped. The CPU 51, ROM 52, RAM 53, and backup RAM 54 are connected to each other via a bus 57, and are connected to an external input circuit 55 and an external output circuit 56.

  A crank position sensor 15, a cam position sensor 23, an accelerator position sensor 27, a vacuum sensor 28, and the like are connected to the external input circuit 55. On the other hand, the fuel injection valve 4 and the like are connected to the external output circuit 56.

  The ECU 5 calculates a final fuel injection amount used for controlling the amount of fuel injected from the fuel injection valve 4 based on the engine speed, the load factor, and the like.

  Here, the engine speed is obtained from the detection signal of the crank position sensor 15. The load factor is a value indicating the current load ratio with respect to the maximum engine load of the engine 1, and is calculated from a parameter corresponding to the intake air amount of the engine 1 and the engine speed NE. The parameters corresponding to the intake air amount include the intake pressure obtained from the detection signal from the vacuum sensor 28, the accelerator depression amount obtained from the detection signal from the accelerator position sensor 27, and the like. The ECU 5 controls the drive of the fuel injection valve 4 based on the final fuel injection amount calculated by the above calculation, and controls the amount of fuel injected from the fuel injection valve 4.

  Next, the structure of the fuel supply device 100 for supplying high-pressure fuel to the fuel injection valve 4 will be described with reference to FIG. FIG. 3 is a diagram schematically showing the structure of the fuel supply device 100 in the present embodiment.

  As shown in FIG. 3, the fuel supply device 100 includes a feed pump 102 that sends fuel from a fuel tank 101, and pressurizes the fuel sent by the feed pump 102 to pressurize the fuel injection valves 4 of each cylinder (four cylinders). And a high-pressure fuel pump 103 that discharges toward.

  The high-pressure fuel pump 103 includes a cylinder 130, a plunger 131, and a pressurizing chamber 132. The plunger 131 is driven by the rotation of a cam 321 attached to the exhaust camshaft 32 and reciprocates in the forward / backward direction (vertical direction) in the cylinder 130. In this embodiment, two cam peaks are formed on the cam 321 with an angular interval of 180 ° around the rotation axis of the exhaust camshaft 32. The plunger 131 is pushed up by the cam crest so that the plunger 131 moves in the cylinder 130. In addition, since the engine 1 according to the present embodiment is a four-cylinder type, one time each from the fuel injection valve 4 provided for each cylinder during one cycle of the engine 1, that is, while the crankshaft 13 rotates twice. A total of four fuel injections are performed. Further, in this engine 1, the exhaust camshaft 32 rotates once every time the crankshaft 13 rotates twice. Therefore, the fuel injection from the fuel injection valve 4 is performed four times, and the discharge operation from the high-pressure fuel pump 103 is performed two times at maximum, every cycle of the engine 1.

  The pressurizing chamber 132 is partitioned by the plunger 131 and the cylinder 130. The pressurizing chamber 132 communicates with the feed pump 102 via the low-pressure fuel pipe 104 constituting the low-pressure fuel passage, and communicates with the inside of the delivery pipe 106 via the high-pressure fuel pipe 105 constituting the high-pressure fuel passage. ing. In this case, the high-pressure fuel pipe 105 and the delivery pipe 106 constitute a fuel injection system.

  This delivery pipe 106 is connected to fuel injection valves 4, 4,... And a return pipe 172 via a relief valve 171. The relief valve 171 opens when the fuel pressure in the delivery pipe 106 exceeds a predetermined pressure (for example, 13 MPa). By opening the relief valve 171, part of the fuel stored in the delivery pipe 106 is returned to the fuel tank 101 via the return pipe 172. Thereby, an excessive increase in the fuel pressure in the delivery pipe 106 is prevented. Further, the return pipe 172 and the high-pressure fuel pump 103 are connected by an excess fuel return pipe 108 (shown by a broken line in FIG. 3), and the fuel leaked from the gap between the plunger 131 and the cylinder 130 becomes the excess fuel. The fuel is returned to the return pipe 172 via the fuel return pipe 108.

  The low-pressure fuel pipe 104 is provided with a filter 141 and a pressure regulator 142. The pressure regulator 142 returns the fuel in the low-pressure fuel pipe 104 to the fuel tank 101 when the fuel pressure in the low-pressure fuel pipe 104 exceeds a predetermined pressure (for example, 0.4 MPa). The fuel pressure is maintained below a predetermined pressure. In addition, the low-pressure fuel pipe 104 is the reverse of the fuel supply means that enables the supply of fuel from the low-pressure fuel pipe 104 to the pressurization chamber 132 when the fuel pressure in the pressurization chamber 132 becomes a predetermined pressure or less. A stop valve 137 is provided. The check valve 137 prevents the fuel pressurized in the pressurizing chamber 132 from flowing back into the low pressure fuel pipe 104.

  Further, the high-pressure fuel pipe 105 enables the fuel to be pumped from the pressurization chamber 132 to the delivery pipe 106 via the high-pressure fuel pipe 105 when the pressure of the fuel in the pressurization chamber 132 becomes equal to or higher than a predetermined pressure. A check valve 151 is provided as fuel pumping means. The check valve 151 prevents the fuel discharged from the high pressure fuel pump 103 from flowing backward.

  The upper end surface as the tip of the plunger 131 is located in the pressurizing chamber 132, and the lower surface of the upper plunger 133 that reciprocates in the forward / backward direction is grounded to the upper end surface of the plunger 131. The upper plunger 133 reciprocates in the forward / backward direction together with the plunger 131, and can be separated in the forward / backward direction with respect to the upper end surface of the plunger 131. The lower part of the upper plunger 133 is located in the pressurizing chamber 132 and has a wide flange 133a at the upper end. The upper plunger 133 is urged by a coil spring 134 as urging means, that is, in a direction in which the lower surface of the upper plunger 133 is grounded to the upper end surface of the plunger 131 (downward in FIG. 3).

  Further, the position of the upper plunger 133 in the withdrawal direction is regulated against the urging force of the coil spring 134 by a plate that contacts the lower surface of the flange portion 133a. The plate 135 is provided so as to be able to reciprocate in the forward / backward direction of the upper plunger 133, and is positioned at a desired position in the forward / backward direction by a plate driving means (not shown), and when the flange 133 a comes into contact with this, the upper plunger 133 is retracted. The position in the direction is arbitrarily regulated. The plate driving means includes an electromagnetic solenoid, and the plate 135 is positioned at a desired position in the forward / backward direction by linearly controlling the current value to the electromagnetic solenoid. In FIG. 3, reference numeral 136 denotes a stopper that regulates the maximum advance position of the upper plunger 133 that reciprocates while being in contact with the upper end surface of the plunger 131.

  As shown in FIG. 4, when the pressure in the pressurizing chamber 132 becomes equal to or lower than a predetermined pressure, the low-pressure fuel pipe 104 specifically controls the position of the upper plunger 133 in the advance direction by the plate 135. In this state, when the plunger 131 moves backward in the direction in which the volume of the pressurizing chamber 132 increases (intake stroke), fuel can be supplied to the pressurizing chamber 132 via the check valve 137. On the other hand, as shown in FIG. 5, when the pressure in the pressurizing chamber 132 exceeds a predetermined pressure, specifically, the position of the upper plunger 133 in the advancing direction is regulated by the plate 135. When the plunger 131 moves in the direction in which the volume contracts (pressurization stroke), the fuel pressurized in the pressurizing chamber 132 can be pumped to the delivery pipe 106 via the check valve 151.

  Here, the fuel path based on the reciprocating movement of the upper plunger 133 and the plunger 131 in the forward and backward directions will be described with reference to FIGS.

  First, as shown in FIGS. 5A and 5B, the upper plunger 133 is in contact with the plate 135 located at the lowest end position because no current is supplied to the electromagnetic solenoid of the plate driving means. Therefore, the upper plunger 133 urged in the retreat direction (downward in the figure) by the urging force of the coil spring 134 reciprocates in the cylinder 130 based on the rotation of the cam 321. While being in contact with the upper end surface, the plunger 131 reciprocates in the forward / backward direction. At this time, since the upper plunger 133 moves in the forward / backward direction together with the plunger 131, the volume of the pressurizing chamber 132 does not change even if the plunger 131 moves in the forward / backward direction, and the fuel pressure in the pressurizing chamber 132 does not change. Therefore, neither the intake of fuel from the low pressure fuel pipe 104 side nor the discharge of fuel to the high pressure fuel pipe 105 side is performed.

  Further, as shown in FIG. 6B, when a predetermined current value is supplied to the electromagnetic solenoid of the plate driving means, the plate 135 moves forward from the lowermost position and is positioned at a desired position. As shown in FIG. 6A, when the upper plunger 133 at the most advanced position moves together with the plunger 131 in the retracting direction, the flange 133a of the upper plunger 133 comes into contact with the plate 135, and the upper plunger 133 retracts. The position in the direction is regulated against the urging force of the coil spring 134. At this time, the volume of the pressurizing chamber 132 is added by moving only the plunger 131 in the retracting direction (during the suction stroke) because the position of the upper plunger 133 in the retracting direction is regulated by contact with the plate 135. Since the volume of the pressure chamber 132 increases and the pressure of the fuel in the pressurizing chamber 132 becomes equal to or lower than a predetermined pressure, the fuel delivered from the feed pump 102 is sucked (supplied) into the pressurizing chamber 132 via the low-pressure fuel pipe 104. )

  When the plunger 131 that has moved to the most retracted position moves in the advance direction based on the rotation of the cam 321, the volume of the pressurizing chamber 132 contracts due to the movement of only the plunger 131 in the advance direction (during the compression stroke). Since the pressure of the fuel in the pressure chamber 132 becomes equal to or higher than a predetermined pressure, the fuel is pumped to the high pressure fuel pipe 105 side via the check valve 151. At this time, a volume of fuel corresponding to the amount of movement of the plunger 133 in the advancing direction until the plunger 131 comes into contact with the lower surface of the upper plunger 133 from the most retracted position is pumped to the delivery pipe 106 via the high-pressure fuel pipe 105. The

  Thereafter, when the upper plunger 133 moves together with the plunger 131 in the advancing direction, the plate 135 moves in the advancing / retreating direction in response to the fuel pressure request. At this time, if there is no request for fuel pumping, the plate 135 is positioned at the lowermost position.

  As described above, according to the first embodiment, the fuel discharge amount is adjusted by adjusting the position of the upper plunger 133 that is regulated by the plate 135 in the retracting direction, so that the electromagnetic spill valve is closed during the pumping stroke. There is no need to adjust the fuel discharge amount by adjusting the period. For this reason, the electromagnetic spill valve is not required, and the shock generated when the electromagnetic spill valve is closed and seated on the seat is not transmitted to the outside as abnormal noise. Thus, frequent abnormal noise due to an impact at the time of the closing operation of the electromagnetic spill valve that occurs each time the plunger 131 reciprocates can be prevented, and the merchantability can be improved.

  In addition, when the position of the upper plunger 133 in the retracting direction is regulated against the biasing force of the coil spring 134, only the plunger 131 moves in the retracting direction in the direction in which the volume of the pressurizing chamber 132 increases. While the fuel is absorbed in the pressure chamber 132, only the plunger 131 moves forward in the direction in which the volume of the pressure chamber 132 contracts, so that the fuel in the pressure chamber 132 is pressurized. The fuel discharge amount is adjusted based on the position of the upper plunger 133 in the retracted direction. For this reason, when the fuel in the pressurizing chamber 132 is not discharged to the high-pressure fuel passage 105 side, as in the case where the fuel in the pressurizing chamber is pressurized each time the plunger reciprocates in the forward / backward direction, the pressurizing chamber 132 is set. There is no need to open the low pressure fuel passage 104. This eliminates the need for the fuel in the pressurizing chamber 132 to flow back to the low pressure fuel passage 104 side, eliminates the waste of returning the fuel pressurized in the pressurizing chamber 132 back to the low pressure fuel passage 104 side, and improves energy efficiency. Can be increased.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the layout of the coil spring and the plate of the high pressure fuel pump is changed. The rest of the configuration excluding the coil spring and the plate is the same as in the case of the first embodiment, and the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  That is, in this embodiment, as shown in FIGS. 7 and 8, the coil spring 134 'as the urging means is retracted below the flange 133a of the upper plunger 133, and the upper plunger 133 is moved forward (see FIG. 7). Then it is energized upward. The plate 135 ′ is driven by plate driving means so as to reciprocate in the forward / backward direction in accordance with the plunger 131 while being in contact with the upper surface of the flange 133 a of the upper plunger 133. In other words, the plate 135 ′ moves the upper plunger 133, which is about to move in the advance direction by the urging force of the coil spring 134 ′, to move in the forward / backward direction together with the plunger 131 with the lower surface grounded to the upper end surface of the plunger 131. It moves in the forward / backward direction while pressing the part 133a.

  When the plunger 131 moves in the retracting direction, the plate 135 'is positioned at a desired position on the movement trajectory of the upper plunger 133 in the advancing / retreating direction by the plate driving means, and when the plunger 131 moves in the retracting direction, the coil spring is moved. The position in the advance direction of the upper plunger 133 urged in the advance direction by 134 'is regulated. At this time, the position of the upper plunger 133 in the advance direction is regulated by the plate 135 ′, so that only the plunger 131 moves in the retreat direction based on the cam 321, and the lower surface of the upper plunger 133 is separated from the upper end surface of the plunger 131. Is done.

  Here, the fuel path based on the reciprocating movement of the upper plunger 133 and the plunger 131 in the forward and backward directions will be described with reference to FIGS.

  First, as shown in FIGS. 7A and 7B, the plate 135 ′ presses the upper surface of the flange 133a of the upper plunger 133 against the urging force in the advance direction by the coil spring 134 ′. Yes. As a result, the upper plunger 133 pressed by the plate 135 ′ that moves in the forward / backward direction according to the plunger 131 is in contact with the upper end surface of the plunger 131 that reciprocates in the forward / backward direction within the cylinder 130 based on the rotation of the cam 321. Then, it reciprocates in the forward / backward direction together with the plunger 131. At this time, since the upper plunger 133 moves in the forward / backward direction together with the plunger 131, the volume of the pressurizing chamber 132 does not change even if the plunger 131 moves in the forward / backward direction, and the fuel pressure in the pressurizing chamber 132 does not change. Therefore, neither the intake of fuel from the low pressure fuel pipe 104 side nor the discharge of fuel to the high pressure fuel pipe 105 side is performed.

  Further, as shown in FIG. 8A, when the plunger 131 moves in the retracting direction, the plate driving means positions the plate 135 ′ at a desired position on the movement locus of the upper plunger 133 in the advancing / retreating direction. The position of the upper plunger 133 biased in the advance direction by the coil spring 134 'is restricted in the advance direction. At this time, since the position of the upper plunger 133 in the advance direction is regulated by the plate 135 ', only the plunger 131 moves in the retreat direction (during the suction stroke), and the volume of the pressurizing chamber 132 increases, Since the fuel pressure in the chamber 132 becomes equal to or lower than a predetermined pressure, the fuel sent out from the feed pump 102 is sucked (supplied) into the pressurizing chamber 132 through the low-pressure fuel pipe 104.

  When the plunger 131 that has moved to the most retracted position moves in the advance direction based on the rotation of the cam 321, the volume of the pressurizing chamber 132 contracts due to the movement of only the plunger 131 in the advance direction (during the compression stroke). Since the pressure of the fuel in the pressure chamber 132 becomes equal to or higher than a predetermined pressure, the fuel is pumped to the high pressure fuel pipe 105 side via the check valve 151. At this time, a volume of fuel corresponding to the amount of movement of the plunger 133 in the advancing direction until the plunger 131 comes into contact with the lower surface of the upper plunger 133 from the most retracted position is pumped to the delivery pipe 106 via the high-pressure fuel pipe 105. The

  Thereafter, when the lower surface of the upper plunger 133 comes into contact with the upper end surface of the plunger 131, as shown in FIG. 8B, the positioning of the plate 135 ′ to the desired position by the plate driving means is released, and the upper plunger 133 advances. The position restriction in the direction is also released. As a result, the plate 135 ′ and the upper plunger 133 move together with the plunger 131 in the advance direction. At this time, if there is a request to pump fuel, when the plunger 131 moves in the retreating direction, the plate driving means positions the plate 135 ′ at a desired position on the movement locus of the upper plunger 133 in the reciprocating direction, and the coil spring 134. The position in the advancing direction of the upper plunger 133 biased in the advancing direction by 'is regulated. On the other hand, if there is no request for pumping fuel, the plate 135 ′ is in a state where the upper plunger 133 is grounded on the upper end surface of the plunger 131 that moves in the forward / backward direction within the cylinder 130 based on the rotation of the cam 321. At the same time, it moves back and forth in the forward and backward direction.

  As described above, according to the second embodiment, the fuel discharge amount is adjusted by adjusting the position in the advance direction of the upper plunger 133 regulated by the plate 135 ′, so that the electromagnetic spill valve is closed during the pumping stroke. It is not necessary to adjust the fuel discharge amount by adjusting the valve period. For this reason, the electromagnetic spill valve is not required, and the shock generated when the electromagnetic spill valve is closed and seated on the seat is not transmitted to the outside as abnormal noise. Thus, frequent abnormal noise due to an impact at the time of the closing operation of the electromagnetic spill valve that occurs each time the plunger 131 reciprocates can be prevented, and the merchantability can be improved.

  In addition, when the position of the upper plunger 133 in the advancing direction is regulated against the urging force of the coil spring 134 ', only the plunger 131 moves in the retracting direction in the direction in which the volume of the pressurizing chamber 132 increases. While the fuel is absorbed in the pressurizing chamber 132, the fuel in the pressurizing chamber 132 is pressurized by moving only the plunger 131 in the direction in which the volume of the pressurizing chamber 132 contracts. The fuel discharge amount is adjusted based on the position in the advance direction of the upper plunger 133 regulated by the above. For this reason, when the fuel in the pressurizing chamber 132 is not discharged to the high-pressure fuel passage 105 side, as in the case where the fuel in the pressurizing chamber is pressurized each time the plunger reciprocates in the forward / backward direction, the pressurizing chamber 132 is set. There is no need to open the low pressure fuel passage 104. This eliminates the need for the fuel in the pressurizing chamber 132 to flow back to the low pressure fuel passage 104 side, eliminates the waste of returning the fuel pressurized in the pressurizing chamber 132 back to the low pressure fuel passage 104 side, and improves energy efficiency. Can be increased.

  In addition, this invention is not limited to said each Example, The other various modifications are included. For example, in each of the above embodiments, the case where the present invention is applied to an in-cylinder direct injection type four-cylinder gasoline engine mounted on an automobile has been described. However, the present invention is not limited thereto, and for example, an in-cylinder direct injection type six cylinder The present invention can be applied to a gasoline engine having any other number of cylinders such as a gasoline engine. Further, the present invention is not limited to a gasoline engine, but can be applied to other internal combustion engines such as a diesel engine. Furthermore, the engine to which the present invention is applicable is not limited to an automobile engine.

  Further, the fuel injection system of the internal combustion engine to which the fuel pipe according to the present invention is applied is not necessarily limited to the one having the delivery pipe 106. For example, the present invention can also be applied to an engine that does not include a delivery pipe, includes a pressure regulator in the fuel supply passage, and adjusts the fuel pressure by returning excess fuel to the fuel tank by the pressure regulator. It is.

  Further, in the high-pressure fuel pump 103 in each of the above embodiments, the plunger 131 is driven by the rotation of the cam 321 attached to the exhaust camshaft 32. However, the plunger is driven by the rotation of the cam attached to the intake camshaft 22. 131 may be driven.

It is a figure which shows schematic structure of the engine which concerns on Example 1 of this invention. It is a block diagram which similarly shows the control system of a fuel-injection control apparatus. Similarly, it is a figure which shows typically the structure of a fuel supply apparatus when it is the state which the plunger and the upper plunger moved to the most advanced direction. Similarly, it is a figure which shows typically the structure of a fuel supply apparatus when it is the state which the plunger and the upper plunger moved to the most retracted direction. Similarly, (a) is a cross-sectional view schematically showing the structure of the high-pressure fuel pump when the plunger and the upper plunger are moved in the most retracted direction, and (b) is the plunger and the upper plunger moving in the most advanced direction. It is sectional drawing which shows typically the structure of a high pressure fuel pump when it is in the state which was carried out. Similarly, (a) is a cross-sectional view schematically showing the structure of the high-pressure fuel pump when the position of the upper plunger in the retracted direction is restricted and only the plunger moves in the most retracted direction. FIG. 5 is a cross-sectional view schematically showing the structure of the high-pressure fuel pump when the plunger and the upper plunger are moved in the most advanced direction from a state in which the position of the upper plunger in the withdrawal direction is regulated. It is a figure which shows the structure of the high pressure fuel pump which concerns on Example 2 of this invention, (a) is a cross section which shows typically the structure of a high pressure fuel pump when the plunger and the upper plunger have moved in the most retracted direction It is a figure, (b) is sectional drawing which shows typically the structure of a high pressure fuel pump when a plunger and an upper plunger are the states which moved to the most advanced direction. Similarly, (a) is a cross-sectional view schematically showing the structure of the high-pressure fuel pump when the position of the upper plunger in the advancing direction is restricted and only the plunger moves in the most retracted direction. FIG. 5 is a cross-sectional view schematically showing the structure of the high-pressure fuel pump when the plunger and the upper plunger are moved in the most advanced direction from the state where the position of the upper plunger in the advanced direction is regulated.

Explanation of symbols

1 engine (internal combustion engine)
4 Fuel Injection Valve 101 Fuel Tank 103 High Pressure Fuel Pump 104 Low Pressure Fuel Passage (Low Pressure Fuel Pipe)
105 High-pressure fuel passage (fuel injection system)
106 Delivery pipe (fuel injection system)
131 Plunger 132 Pressurizing chamber 133 Upper plunger 134 Coil spring (biasing means)
134 'coil spring (biasing means)
135 Plate 135 ′ Plate 137 Check valve (fuel supply means)
151 Check valve (fuel pressure feeding means)

Claims (2)

A high-pressure fuel pump for an internal combustion engine configured to pressurize fuel supplied from a fuel tank through a low-pressure fuel pipe in a pressurizing chamber and pump the fuel to a fuel injection system of the internal combustion engine,
A plunger that adjusts the pressure in the pressurizing chamber by reciprocating in the forward / backward direction based on rotation of the cam;
Fuel supply means for enabling supply of fuel from the low-pressure fuel pipe to the pressurization chamber when the pressure in the pressurization chamber becomes a predetermined pressure or lower;
Fuel pumping means that enables pumping of fuel from the pressurizing chamber to the fuel injection system when the pressure in the pressurizing chamber becomes equal to or higher than a predetermined pressure;
An upper plunger that is grounded so as to be separable in the advancing and retreating direction with respect to the tip of the plunger in the pressurizing chamber, and reciprocating in the advancing and retreating direction together with the plunger;
An urging means for urging the upper plunger in a direction to contact the tip of the plunger;
A plate that is reciprocally movable in the advance and retreat direction of the upper plunger and restricts the position of the upper plunger in the retreat direction against the urging force of the urging means;
A high-pressure fuel pump for an internal combustion engine, comprising: plate driving means for reciprocating the plate to position the plate at a desired position. A high-pressure fuel pump for an internal combustion engine configured to pressurize fuel supplied from a fuel tank through a low-pressure fuel pipe in a pressurizing chamber and pump the fuel to a fuel injection system of the internal combustion engine,
A plunger that adjusts the pressure in the pressurizing chamber by reciprocating in the forward / backward direction based on rotation of the cam;
Fuel supply means for enabling supply of fuel from the low-pressure fuel pipe to the pressurization chamber when the pressure in the pressurization chamber becomes a predetermined pressure or lower;
Fuel pumping means that enables pumping of fuel from the pressurizing chamber to the fuel injection system when the pressure in the pressurizing chamber becomes equal to or higher than a predetermined pressure;
An upper plunger that is grounded so as to be separable in the advancing and retreating direction with respect to the tip of the plunger in the pressurizing chamber, and reciprocating in the advancing and retreating direction together with the plunger
An urging means for urging the upper plunger in a direction to move away from the tip of the plunger;
A plate that is reciprocally movable in the advancing and retreating direction of the upper plunger, and that reciprocates together with the plunger in a state where the upper plunger is grounded against the urging force of the urging means,
A plate for reciprocating the plate and positioning the plate at a desired position so as to restrict the position of the upper plunger in the advance direction against the biasing force of the biasing means when the plunger moves in the retracting direction. A high-pressure fuel pump for an internal combustion engine.

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