JP2008115753A - Fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device for an internal combustion engine capable of effectively inhibiting transmission of fuel pressure pulsation generated by the drive of a high pressure pump. <P>SOLUTION: This device is provided with: a low pressure pump 71 capable of feeding fuel with pressurizing the same to predetermined feed pressure; a high pressure pump 72 capable of pressurizing and feeding fuel pressurized by the low pressure pump 71; a fuel injection means 73 capable of injecting pressurized fuel, a low pressure passage 74 connecting the low pressure pump 71 and the high pressure pump 72; a high pressure passage 75 connecting the high pressure pump 72 and the fuel injection means 73; a bypass passage 81 connecting the low pressure passage 74 and the high pressure passage 75 or the fuel injection means 73; a pulsation reduction means 82 provided in the bypass passage 81 and reducing pulsation of fuel; a bypass passage reverse flow prevention means 83 preventing reverse flow of fuel in the bypass passage 81; and a high pressure passage check valve 77 preventing reverse flow of fuel in the high pressure passage 75 and having valve open pressure set higher than feed pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel supply device for an internal combustion engine, and more particularly to a fuel supply device for an internal combustion engine that pressurizes and pressurizes already pressurized fuel.

  Among internal combustion engines mounted on vehicles such as passenger cars and trucks, there is a direct injection type internal combustion engine that supplies fuel directly into the combustion chamber of each cylinder of the internal combustion engine. In such a fuel supply device for an internal combustion engine, in order to atomize the fuel, the fuel in the fuel tank is pumped up by an electric low-pressure fuel pump and pressurized to a predetermined feed pressure, and the fuel is further added by a high-pressure fuel pump. Some of them are pressurized and sent to the fuel injection valve via the delivery pipe. In such a high-pressure fuel pump, for example, there is a pump in which the plunger reciprocates by a cam interlocked with the crankshaft. In this case, this reciprocation includes a suction stroke in which the plunger moves in a direction to increase the volume of the pressure chamber, and a pressure-feed stroke in which the plunger moves in a direction to decrease the volume. Further, in such a high-pressure fuel pump, a spill valve is provided in a fuel inflow path communicating with the pressure chamber, and the spill valve is opened in the suction stroke and closed in the pressure feed stroke, so that suction and pressurization are performed. The amount of fuel used is metered.

  By the way, when the plunger is reciprocated by the cam interlocked with the crankshaft as described above, the position of the plunger is a position corresponding to the crank angle. Therefore, in such a fuel supply device, the position of the plunger corresponding to the crank angle is detected, and the closing timing of the spill valve is set accordingly. In this case, for example, in a relatively quiet operation region such as an idling operation, an operation sound accompanying opening and closing of the spill valve may be a problem. Here, in such idling operation after warm-up, the temperature of the engine water is high, the fuel is relatively easy to vaporize and atomize, and since the rotation speed is low, the period from fuel injection to ignition is relatively long. Since the internal pressure is also relatively low, the fuel can be sufficiently vaporized and atomized by injecting the fuel at the feed pressure. Therefore, in the idling operation after warm-up, the spill valve opening / closing operation is stopped in the open state, and the fuel pressurized to the feed pressure by the low-pressure fuel pump is not further pressurized and passes through the high-pressure fuel pump as it is. In addition, there is a fuel supply device that reduces the operation noise by supplying fuel to the delivery pipe and the fuel injection valve with feed pressure (feed pressure operation).

  However, in this case, since the plunger of the high-pressure fuel pump reciprocates in conjunction with the rotation of the crankshaft, even if the spill valve is opened and the pressurization of fuel in the high-pressure fuel pump is stopped, the plunger Continues to drive. For this reason, fuel pressure pulsation accompanying the reciprocating motion of the plunger is generated, and this pulsation fluctuates the pressure of the fuel in the passage, that is, the fuel pressure, and the fluctuation of the fuel pressure propagates to the delivery pipe and the fuel injection valve. The control means of the internal combustion engine controls the injection timing and the injection amount of the fuel injected from the fuel injection valve according to the operating state, and the pressure pulsation propagates to the delivery pipe and the fuel injection valve as described above, so that the fuel There is an error in the fuel injection amount by the injection valve, and therefore, a predetermined fuel supply amount to be supplied to the internal combustion engine cannot be supplied from the fuel injection device, which may deteriorate the controllability of the air-fuel ratio. In particular, when fuel is injected at a feed pressure during idling after warm-up as described above, the effect of pressure pulsation on the injection pressure increases, so it is important to reduce this pressure pulsation.

  As a technique for reducing such pressure pulsation, for example, in a fuel supply device for an internal combustion engine described in Patent Document 1, fuel is pressurized by a low-pressure pump and the pressurized fuel is supplied to a low-pressure fuel injection mechanism. A low-pressure fuel supply system, and a high-pressure fuel supply system that branches from the low-pressure fuel supply system and pressurizes the fuel pressurized by the low-pressure pump by the high-pressure pump and supplies the further pressurized fuel to the high-pressure fuel injection mechanism Further, by extending the pipe between the high pressure pump and the low pressure fuel injection mechanism, the pressure pulsation generated by the high pressure pump is attenuated, and the pressure pulsation is prevented from propagating to the low pressure fuel injection mechanism.

JP 2005-106027 A

  However, even if the configuration of extending the pipe provided in the fuel supply device for an internal combustion engine described in Patent Document 1 described above is applied to, for example, a pipe connecting a high-pressure pump and a high-pressure delivery pipe, it is generated by the high-pressure pump. Although it is possible to suppress the propagation of the pressure pulsation to the high-pressure delivery pipe, the volume of the high-pressure fuel supply system increases, and as a result, there is a risk that the boosting at the start will be delayed. Extension piping must be provided in a limited space between the delivery pipe and the installation space is not efficient.

  Therefore, an object of the present invention is to provide a fuel supply device for an internal combustion engine that can effectively suppress the propagation of fuel pressure pulsation generated by driving a high-pressure pump.

  In order to achieve the above object, a fuel supply device for an internal combustion engine according to the invention according to claim 1 is driven according to an operating state of the internal combustion engine, a low pressure pump capable of pressurizing and feeding fuel to a predetermined feed pressure, A metering valve opens and closes the suction port to adjust the amount of fuel pressurized by the low-pressure pump and to pressurize and feed the pressurized fuel, and the pressurized fuel to the combustion chamber or the combustion chamber The fuel injection means that can inject into the communicating intake port, the low-pressure passage that connects the low-pressure pump and the high-pressure pump, the high-pressure passage that connects the high-pressure pump and the fuel injection means, and a branch from the low-pressure passage A bypass passage having a bypass branch portion and a bypass connection portion connected to the high-pressure passage or the fuel injection means; pulsation reduction means provided in the bypass passage for reducing fuel pulsation; and A bypass passage backflow prevention means for preventing the backflow of fuel from the bypass connection side to the bypass branch side and a valve opening pressure set lower than the feed pressure; and the fuel injection means side to the high pressure pump side A high-pressure passage check valve that prevents back flow of the fuel and has a valve opening pressure higher than the feed pressure and higher than a pulsation pressure of the fuel accompanying the driving of the high-pressure pump. To do.

  In the fuel supply device for an internal combustion engine according to the second aspect of the invention, the high-pressure pump can reciprocate in conjunction with the rotation of the crankshaft of the internal combustion engine to suck in fuel from the suction port and pressurize the pressure. And the metering valve is opened to inhale fuel, and is closed to pressurize and pump.

  In the fuel supply apparatus for an internal combustion engine according to the invention according to claim 3, the pulsation reducing means determines the length of the bypass side passage from the high pressure pump to the bypass connecting portion via the bypass passage as the high pressure side passage of the high pressure passage. It is characterized by being configured by setting it longer than the length.

  The fuel supply device for an internal combustion engine according to a fourth aspect of the invention is characterized in that the pulsation reducing means includes a throttle portion that restricts the passage area of the fuel and an attenuator that attenuates the pulsation of the fuel.

  In a fuel supply apparatus for an internal combustion engine according to a fifth aspect of the present invention, the bypass branch portion is provided on the low pressure pump side in the low pressure passage.

  In the fuel supply apparatus for an internal combustion engine according to the sixth aspect of the invention, the bypass passage backflow prevention means is provided on the bypass connection portion side in the bypass passage.

  The internal combustion engine fuel supply apparatus according to claim 7 is characterized in that the bypass passage backflow prevention means is constituted by an electromagnetic valve.

  An internal combustion engine fuel supply apparatus according to an eighth aspect of the invention includes a relief valve that discharges excess fuel from the fuel injection means to the bypass passage.

  In a fuel supply apparatus for an internal combustion engine according to a ninth aspect of the present invention, the bypass passage flow preventing means includes an electromagnetic relief valve that discharges excess fuel from the fuel injection means to the bypass passage.

  A fuel supply device for an internal combustion engine according to a tenth aspect of the present invention includes control means for controlling the metering valve to an open state when the operating state of the internal combustion engine is an idling state after warming up. .

  According to the fuel supply device for an internal combustion engine according to the present invention, a bypass passage having a bypass branch portion branched from the low pressure passage and a bypass connection portion connected to the high pressure passage or the fuel injection means, and the fuel injection means side to the high pressure pump side A high-pressure passage check valve is set in the bypass passage, which prevents back-flow of fuel to the valve and has a valve opening pressure higher than the feed pressure and higher than the pulsation pressure of the fuel accompanying the drive of the high-pressure pump. Since the pulsation reducing means for reducing the pulsation of the fuel is provided, propagation of the fuel pressure pulsation generated by driving the high-pressure pump can be effectively suppressed.

  Embodiments of a fuel supply device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic configuration diagram showing a fuel system of a fuel supply device for an internal combustion engine according to a first embodiment of the present invention, and FIG. 2 is an engine to which the fuel supply device for the internal combustion engine according to the first embodiment of the present invention is applied. It is a schematic block diagram which shows.

  As shown in FIG. 2, in this embodiment, the fuel supply device 1 for an internal combustion engine according to the present invention is applied to an engine 10 as an internal combustion engine. The engine 10 is a 6-cylinder in-cylinder injection type, and a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are fitted to a plurality of cylinder bores 13 formed in the cylinder block 11 so as to be movable up and down. is doing. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 14, and the combustion chamber 18 has a high central portion at the upper portion (lower surface of the cylinder head 12). It has a pent roof shape that is slanted. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 19 and the exhaust valve 20 are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction (upward in FIG. 2) for closing the intake port 19 and the exhaust port 20. ing. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported on the cylinder head 12, and the intake cam 25 and the exhaust cam 26 are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, an endless timing chain is wound around the crankshaft sprocket fixed to the crankshaft 16 and the camshaft shaft sprockets fixed to the intake camshaft 23 and the exhaust camshaft 24, respectively. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam 25 and the exhaust cam 26 move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. 19 and the exhaust port 20 can be opened and closed so that the intake port 19 and the combustion chamber 18 can communicate with the combustion chamber 18 and the exhaust port 20, respectively. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine 10 executes the four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 are set to one. It will rotate.

  In addition, the valve mechanism of the engine 10 is a variable valve timing-intelligent (VVT) mechanism 27 or 28 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. It has become. The intake / exhaust variable valve mechanisms 27 and 28 are configured by providing VVT controllers 29 and 30 at the shaft end portions of the intake camshaft 23 and the exhaust camshaft 24, and the hydraulic pressure from the oil control valves 31 and 32 is supplied to the intake camshaft and exhaust camshaft 24. The phase of the camshafts 23 and 24 with respect to the cam sprocket is changed by acting on the advance chamber and the retard chamber (not shown) of the VVT controllers 29 and 30, and the opening / closing timing of the intake valve 21 and the exhaust valve 22 is advanced or retarded. Is something that can be done. In this case, the intake / exhaust variable valve mechanisms 27, 28 advance or retard the opening / closing timing with the operating angle (opening period) of the intake valve 21 and the exhaust valve 22 being constant. In addition, the intake camshaft 23 and the exhaust camshaft 24 are provided with cam position sensors 33 and 34 for detecting their rotational phases.

  A surge tank 36 is connected to the intake port 19 via an intake manifold 35, and an intake pipe 37 is connected to the surge tank 36. An air cleaner 38 is attached to an air intake port of the intake pipe 37. . An electronic throttle device 40 having a throttle valve 39 is provided on the downstream side of the air cleaner 38. The cylinder head 12 is provided with an injector 41 that directly injects fuel into the combustion chamber 18. The injector 41 is located on the intake port 19 side and is inclined at a predetermined angle in the vertical direction. . The injector 41 attached to each cylinder is connected to a delivery pipe 76, and a high pressure fuel pump 72 as a high pressure pump is connected to the delivery pipe 76 via a high pressure fuel supply pipe 75 as a high pressure passage. Here, the high-pressure fuel pump 72 is installed in the cylinder head 12. Further, the cylinder head 12 is provided with a spark plug 45 that is located above the combustion chamber 18 and ignites the air-fuel mixture.

  On the other hand, an exhaust pipe 47 is connected to the exhaust port 20 via an exhaust manifold 46. The exhaust pipe 47 is a three-way element that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas. Catalysts 48 and 49 are mounted. Further, the engine 10 is provided with a starter motor 50 that performs cranking. When an unillustrated pinion gear meshes with the ring gear when the engine is started, the rotational force is transmitted from the pinion gear to the ring gear to rotate the crankshaft 16. Can do.

  Incidentally, an electronic control unit (ECU) 51 is mounted on the vehicle, and the ECU 51 can control the injector 41, the spark plug 45, and the like. That is, an air flow sensor 52 and an intake air temperature sensor 53 are mounted on the upstream side of the intake pipe 37, and an intake pressure sensor 54 is provided in the surge tank 36. The measured intake air amount, intake air temperature, intake air pressure (Intake pipe negative pressure) is output to the ECU 51. The electronic throttle device 40 is provided with a throttle position sensor 55, which outputs the current throttle opening to the ECU 51. The accelerator position sensor 56 outputs the current accelerator opening to the ECU 51. Further, the crank angle sensor 57 outputs the detected crank angle of each cylinder to the ECU 51. The ECU 51 determines the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in each cylinder based on the detected crank angle. The engine speed is calculated. The cylinder block 11 is provided with a water temperature sensor 58 that detects the engine cooling water temperature, and outputs the detected engine cooling water temperature to the ECU 51. Further, a delivery pipe 76 communicating with each injector 41 is provided with a fuel pressure sensor 59 for detecting the fuel pressure, and the detected fuel pressure is output to the ECU 51. On the other hand, the exhaust pipe 47 is provided with oxygen sensors 60 and 61 for detecting the oxygen concentration of the exhaust gas located upstream and downstream of the three-way catalyst 48, and outputs the detected oxygen concentration to the ECU 51. ing.

  Therefore, the ECU 51 drives the high-pressure fuel pump 72 based on the detected fuel pressure so that the fuel pressure becomes a predetermined pressure, and detects the intake air amount, intake air temperature, intake air pressure, throttle opening, accelerator opening. The fuel injection amount (fuel injection time), the injection timing, the ignition timing, etc. are determined based on the engine operating state such as the engine speed and the engine coolant temperature, and the injector 41 and the spark plug 45 are driven to perform the fuel injection and ignition. Execute. Further, the ECU 51 feeds back the detected oxygen concentration of the exhaust gas to correct the fuel injection amount so that the air-fuel ratio becomes stoichiometric (theoretical air-fuel ratio).

  The ECU 51 can control the intake / exhaust variable valve operating mechanisms 27 and 28 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idling, or the load is light, the exhaust gas blows back to the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  Here, the fuel system of the fuel supply device 1 of the engine 10 described above will be described in detail.

  As shown in FIG. 1, the fuel supply apparatus 1 of the present embodiment is pressurized by a fuel tank 70, a low-pressure feed pump 71 as a low-pressure pump that pressurizes fuel in the fuel tank 70, and the low-pressure feed pump 71. The high-pressure fuel pump 72 as the above-described high-pressure pump for further pressurizing the fuel and the fuel injection mechanism 73 as the fuel injection means for injecting the pressurized fuel are provided.

  The fuel tank 70 stores fuel supplied to the engine 10, and a low pressure feed pump 71 is attached to the fuel tank 70.

  The low-pressure feed pump 71 can pressurize the fuel in the fuel tank 70 to a predetermined feed pressure, for example, about several hundred kPa by an electric motor, and pump it as low-pressure fuel. The low pressure feed pump 71 is connected to the suction port 72g of the high pressure fuel pump 72 via a low pressure fuel supply pipe 74 as a low pressure passage. The low pressure fuel supply pipe 74 is provided with a low pressure fuel return pipe 74a branched.

  The low pressure fuel return pipe 74 a has a proximal end branched from the low pressure fuel supply pipe 74 in the fuel tank 70, and a distal end is also located in the fuel tank 70. On the low pressure fuel return pipe 74a, a low pressure side relief valve 74b as a low pressure regulating valve is provided. The low-pressure relief valve 74b opens when the fuel pressure in the low-pressure fuel supply pipe 74 (hereinafter referred to as “fuel pressure”) becomes higher than the feed pressure, and is thereby discharged from the low-pressure feed pump 71. Part of the fuel can be returned to the fuel tank 70 via the low-pressure fuel return pipe 74a, and the fuel pressure in the low-pressure fuel supply pipe 74 can be kept constant.

  The high-pressure fuel pump 72 can be driven by the rotation of the crankshaft 16 (see FIG. 2) of the engine 10, and the low-pressure fuel that has already been pressurized by the low-pressure feed pump 71 is supplied from a high pressure, for example, several MPa. This is a metering type high-pressure pump for pressurizing to about several tens of MPa to produce high-pressure fuel and supplying it to the fuel injection mechanism 73. Further, the high-pressure fuel pump 72 has a discharge port 72h connected to a delivery pipe 76 of a fuel injection mechanism 73 described later via a high-pressure fuel supply pipe 75 serving as a high-pressure passage. The high-pressure fuel supply pipe 75 is equipped with a high-pressure passage check valve 77 that prevents a back flow of fuel from the delivery pipe 76 side of the fuel injection mechanism 73 to the high-pressure fuel pump 72 side.

  Here, the high-pressure fuel pump 72 will be described in detail.

  The high-pressure fuel pump 72 includes a casing 72a, a plunger 72b, a pressure chamber 72c, a spill valve 72d as a metering valve, a spring 72e as an urging means, and a solenoid 72f.

  The casing 72a is formed in a cylindrical shape, and a suction port 72g for sucking low pressure fuel is formed at one end portion thereof, and a discharge port 72h for discharging high pressure fuel is formed on a side surface portion thereof. The plunger 72b is supported in the casing 72a so as to be able to reciprocate. The pressure chamber 72c is a space for pressurizing the fuel, and is defined by one end surface of the plunger 72b and the inner surface of the casing 72a. The discharge port 72h is formed so as to communicate with the pressure chamber 72c. The spill valve 72d is provided at the suction port 72g of the casing 72a, is movable in the axial direction of the casing 72a, and can open and close the suction port 72g, thereby communicating the suction port 72g and the pressure chamber 72c. Can do.

  The spill valve 72d is biased by a spring 72e in a direction in which the suction port 72g can be opened, and can be opened and closed by applying a suction force in a direction in which the suction port 72g can be closed by a solenoid 72f. Composed. The solenoid 72f is electrically connected to the ECU 51 (see FIG. 2), and its energization is controlled by a control signal transmitted by the ECU 51.

  The spill valve 72d is a so-called normally open spill valve, that is, when the solenoid 72f is not energized, the spill valve 72d is separated from the inlet 72g by the spring 72e (the direction of the pressure chamber 72c). The intake port 72g is opened (opened state), and fuel can flow through the intake port 72g. On the other hand, when the solenoid 72f is energized, the spill valve 72d is sucked by the solenoid 72f in a direction approaching the suction port 72g (direction of the solenoid 72f), and the suction port 72g is closed (valve closed state). The intake and outflow of fuel through the port 72g are blocked. As a result, even if the solenoid 72f is disconnected, the suction port 72g is maintained in an open state, so that full-pressure feeding is not continued and damage to the fuel supply system is minimized. be able to.

  The plunger 72b is formed in a cylindrical shape whose outer diameter is slightly smaller than the inner diameter of the casing 72a, and is provided so as to be capable of reciprocating with respect to the casing 72a. Further, the plunger 72b forms a pressure chamber 72c on one end face side and is urged so as to be pressed against a cam 72i provided on the other end face side by a spring (not shown). The cam 72i is fixed to the camshaft 72j, and the camshaft 72j rotates in conjunction with the rotation of the crankshaft 16 (see FIG. 2) of the engine 10 via a mechanism (not shown). The cam 72i rotates together with the cam shaft 72j, whereby the plunger 72b is pressed by the cam 72i and reciprocates with respect to the casing 72a.

  The pressure chamber 72c changes its volume according to the reciprocating motion of the plunger 72b, so that the fuel can be sucked from the suction port 72g. Further, the pressure chamber 72c can be pressurized and pumped from the discharge port 72h. Here, the reciprocating movement of the plunger 72b includes a suction stroke in which the plunger 72b moves in the direction of increasing the volume of the pressure chamber 72c, and a pressure-feeding stroke in which the plunger 72b moves in a direction of decreasing the volume. In the suction stroke, the volume of the pressure chamber 72c increases as the plunger 72b moves toward the cam 72i. At this time, the ECU 51 controls the solenoid 72f to be in a non-energized state and opens the suction port 72g. The internal fuel pressure decreases, the suction force for sucking in the fuel acts in the pressure chamber, and the low pressure fuel in the low pressure fuel supply pipe 74 can be sucked into the pressure chamber 72c through the suction port 72g. On the other hand, in the pressure feed stroke, the volume of the pressure chamber 72c is reduced by the plunger 72b moving to the spill valve 72d side. At this time, the ECU 51 controls the solenoid 72f to be in an energized state and closes the suction port 72g. The internal fuel pressure rises and a pressing force that presses the fuel acts in the pressure chamber, and the high-pressure fuel pressurized to a predetermined pressure is pumped from the discharge port 72h to the fuel injection mechanism 73 via the high-pressure fuel supply pipe 75. can do. Further, by adjusting the energization timing of the solenoid 72f, that is, the closing timing of the suction port 72g, the fuel intake amount can be adjusted.

  The fuel injection mechanism 73 includes the above-described delivery pipe 76 and the above-described plurality of injectors 41 connected to the delivery pipe 76. More specifically, a total of six injectors 41 are provided, one for each of the six combustion chambers 18 provided corresponding to the six cylinders. The delivery pipe 76 includes a first delivery pipe 76a and a second delivery pipe 76b, and three injectors 41 are connected to each of the first delivery pipe 76a and the second delivery pipe 76b. In the fuel injection mechanism 73, the first delivery pipe 76 a is connected to the high-pressure fuel supply pipe 75, and the first delivery pipe 76 a and the second delivery pipe 76 b are connected by the connection pipe 78. The fuel pressure sensor 59 described above is provided in the first delivery pipe 76a. A high pressure passage check valve 77 is attached to a high pressure fuel supply pipe 75 that connects the first delivery pipe 76 a and the discharge port 72 h of the high pressure fuel pump 72. Further, a high pressure fuel return pipe 79 is connected to the second delivery pipe 76b.

  The high pressure passage check valve 77 is for keeping the fuel pressure supplied to the delivery pipe 76 constant. The high-pressure passage check valve 77 is opened when the pressure of the low-pressure fuel in the pressure chamber 72c of the high-pressure fuel pump 72 becomes a predetermined pressure, for example, about several tens of MPa, so that the fuel can pass through the high-pressure fuel supply pipe 75. To do. The high-pressure fuel pressurized by the high-pressure fuel pump 72 is supplied to a plurality of injectors 41 via a high-pressure passage check valve 77, a high-pressure fuel supply pipe 75, a first delivery pipe 76a, and a second delivery pipe 76b. The plurality of injectors 41 can atomize the high-pressure fuel in the first delivery pipe 76 a and the second delivery pipe 76 b and directly inject them into the combustion chamber 18 of each cylinder of the engine 10.

  The high pressure fuel return pipe 79 has a proximal end connected to the second delivery pipe 76 b and a distal end located in the fuel tank 70. The high-pressure fuel return pipe 79 is equipped with a high-pressure relief valve 80 as a high-pressure adjusting valve. The high-pressure relief valve 80 is opened when the high-pressure fuel in the first delivery pipe 76a and the second delivery pipe 76b reaches a predetermined pressure, for example, about a dozen MPa or more, so that the fuel pressure exceeds the predetermined pressure. The excess fuel in the first delivery pipe 76a and the second delivery pipe 76b is returned to the fuel tank 70 via the high-pressure fuel return pipe 79, and the first delivery pipe 76a and the second delivery pipe 76b The fuel pressure can be kept constant.

  In the fuel supply device 1 configured as described above, when the engine 10 is started, the low pressure feed pump 71 is driven to pressurize the fuel in the fuel tank 70, and the low pressure fuel is supplied to the high pressure fuel through the low pressure fuel supply pipe 74. The high-pressure fuel pump 72 can further pressurize the low-pressure fuel and supply the high-pressure fuel to the first delivery pipe 76a and the second delivery pipe 76b via the high-pressure fuel supply pipe 75. The injector 41 can inject high-pressure fuel in the first delivery pipe 76 a and the second delivery pipe 76 b into the combustion chamber 18. At this time, the ECU 51 drives and controls the high-pressure fuel pump 72 based on the fuel pressure detected by the fuel pressure sensor 59, and maintains the fuel pressure in the first delivery pipe 76a and the second delivery pipe 76b at a predetermined pressure. When the fuel pressure in the first delivery pipe 76a and the second delivery pipe 76b becomes higher than a predetermined pressure, the high pressure side relief valve 80 is opened and the high pressure fuel is discharged to the fuel tank 70 through the high pressure fuel return pipe 79.

  By the way, as described above, when the plunger 72b is reciprocated by the cam 72i interlocked with the crankshaft 16 in the high-pressure fuel pump 72, the position of the plunger 72b becomes a position corresponding to the crank angle. Therefore, in such a fuel supply device 1, the position of the plunger 72b corresponding to the crank angle is detected, and the valve closing timing of the spill valve 72d is set accordingly.

  Here, in such a fuel supply device 1 of the engine 10, for example, in idling operation after warm-up, the fuel is relatively easy to vaporize and atomize because the engine cooling water temperature is high, and the rotation speed is also low. Since the period from injection to ignition is relatively long and the in-cylinder pressure is relatively low, the fuel can be sufficiently vaporized and atomized even when the fuel is injected at the feed pressure. Therefore, in the fuel supply device 1, the spill valve 72d of the high-pressure fuel pump 72 is opened, and the fuel pressurized to the feed pressure by the low-pressure feed pump 71 is not further pressurized by the high-pressure fuel pump 72. The fuel may be supplied to the fuel injection mechanism 73 while maintaining the pressure (hereinafter referred to as “feed pressure operation”).

  However, in this case, since the plunger 72b of the high-pressure fuel pump 72 reciprocates in conjunction with the rotation of the crankshaft 16, the spill valve 72d is opened, and the pressurization of fuel by the high-pressure fuel pump 72 is stopped. Even so, the plunger 72b continues to be driven. For this reason, fuel pressure pulsation accompanying the reciprocating motion of the plunger 72 b occurs, and this pulsation fluctuates the fuel pressure in the fuel supply passage, and this fuel pressure fluctuation may propagate to the delivery pipe 76 and the injector 41. The ECU 51 controls the injection timing and the injection amount of the fuel injected from each injector 41 according to the operating state, and the pressure pulsation propagates to the delivery pipe 76 and the injector 41 as described above. There is an error in the fuel injection amount, which may deteriorate the controllability of the air-fuel ratio. In particular, when fuel is injected at a feed pressure during idling after warm-up as described above, the effect of pressure pulsation on the injection pressure increases, so it is important to reduce this pressure pulsation.

  Therefore, the fuel supply device 1 of the engine 10 includes a bypass pipe 81 as a bypass passage branched from the low-pressure fuel supply pipe 74 and a pulsation reduction unit 82 as a pulsation reduction means provided in the bypass pipe 81, By setting the valve opening pressure of the high pressure passage check valve 77 to be higher than the feed pressure by the low pressure feed pump 71, propagation of fuel pressure pulsation generated by driving the high pressure fuel pump 72 is effectively suppressed.

  Specifically, the bypass pipe 81 includes a bypass branch part 81 a branched from the low-pressure fuel supply pipe 74 and a bypass connection part 81 b connected to the first delivery pipe 76 a of the fuel injection mechanism 73. That is, the bypass pipe 81 is branched from the low pressure fuel supply pipe 74 at the bypass branch portion 81a, and is connected to the first delivery pipe 76a at the bypass connection portion 81b without passing through the high pressure fuel pump 72. is there. The bypass pipe 81 is provided with a bypass passage check valve 83 as a bypass passage backflow prevention means.

  The bypass passage check valve 83 prevents the fuel from flowing backward from the bypass connection portion 81b side to the bypass branch portion 81a side, and keeps the fuel pressure supplied to the delivery pipe 76 constant. The valve opening pressure of the bypass passage check valve 83 is set slightly lower than the feed pressure. That is, the bypass passage check valve 83 is opened when the fuel pressure in the bypass pipe 81 becomes the feed pressure, whereby the fuel at the feed pressure passes through the bypass pipe 81 and the delivery pipe 76. Can be supplied. The valve opening pressure of the bypass passage check valve 83 is preferably set as low as possible in order to suppress pressure loss.

  The high pressure passage check valve 77 is set such that the valve opening pressure is higher than the feed pressure. In addition to this, the valve opening pressure of the high pressure passage check valve 77 is set higher than the pulsation pressure of the fuel accompanying the reciprocating motion of the plunger 72b.

  Then, the ECU 51 as the control means of the present embodiment controls the open / close operation of the spill valve 72d by deenergizing the solenoid 72f during the idling operation after the warm-up, and stops in the open state, whereby the low-pressure feed pump 71 Thus, the fuel pressurized to the feed pressure is not further pressurized by the high-pressure fuel pump 72, and the fuel is supplied to the fuel injection mechanism 73 at the feed pressure. The ECU 51 determines whether or not the engine 10 is idling after the engine 10 is warmed up. The engine speed detected by the crank angle sensor 57 is an idle speed, or the engine cooling water temperature detected by the water temperature sensor 58 is set to a predetermined value. What is necessary is just to determine by various methods, such as above.

  That is, during normal operation, the high-pressure fuel pump 72 pressurizes the fuel to a feed pressure or higher, whereby the high-pressure passage check valve 77 is opened, and the high-pressure fuel is delivered via the high-pressure fuel supply pipe 75 to the delivery pipe. 76. When the spill valve 72d is opened and the pressurization by the high-pressure fuel pump 72 is stopped, the fuel pressure in the delivery pipe 76 is injected from the injector 41, so that the fuel pressure gradually decreases. At this time, the fuel at the feed pressure reaching the high pressure fuel pump 72 passes through the high pressure fuel pump 72 as it is, and reaches the high pressure passage check valve 77 with the feed pressure. Here, since the valve opening pressure of the high pressure passage check valve 77 is set higher than the feed pressure, the high pressure passage check valve 77 does not open, and the fuel injection mechanism 73 via the high pressure fuel supply pipe 75 does not open. There will be no fuel supply. On the other hand, the fuel pressurized by the low pressure feed pump 71 is introduced into the bypass pipe 81 via the bypass branching portion 81a, reaches the bypass passage check valve 83, and the fuel pressure in the delivery pipe 76 is increased. When the feed pressure becomes lower, the bypass passage check valve 83 opens, fuel at the feed pressure is supplied to the fuel injection mechanism 73, fuel is injected from each injector 41 at the feed pressure, and the feed pressure through the bypass pipe 81. Transition to driving.

  That is, during normal operation, high-pressure fuel is supplied to the fuel injection mechanism 73 via the high-pressure fuel supply pipe 75, and during feed pressure operation, fuel at the feed pressure is supplied to the fuel injection mechanism 73 via the bypass pipe 81. The supply path can be switched. That is, according to the operating state of the engine 10, the feed path of the feed pressure fuel can be switched by a simple control of turning off the solenoid 72 f of the high pressure fuel pump 72 and the operation can be shifted to the feed pressure operation. In addition to the control other than deenergizing the solenoid 72f of the high-pressure fuel pump 72, the supply path is switched according to the fuel pressure due to the mechanical configuration, so that it is possible to quickly shift to the feed pressure operation and to reduce the cost and reliability. It can also be improved.

  At this time, the valve opening pressure of the high-pressure passage check valve 77 is set higher than the fuel pulsation pressure accompanying the reciprocating motion of the plunger 72b. Therefore, the fuel pulsating pressure accompanying the reciprocating motion of the plunger 72b is set. This prevents the high pressure passage check valve 77 from being opened. This prevents the fuel pressure pulsation accompanying the reciprocating motion of the plunger 72b from propagating to the fuel injection mechanism 73 via the high-pressure fuel supply pipe 75 during the feed pressure operation. Note that the upper limit of the valve opening pressure of the high pressure passage check valve 77 is preferably set to a minimum value in a range higher than the pulsation pressure in consideration of variation. This is to prevent the pumping efficiency of the high-pressure fuel pump 72 from being lowered due to an obstacle to the pumping of the fuel pressurized by the high-pressure fuel pump 72 when the valve opening pressure is excessive.

  Further, in the idling operation after the warm-up by the ECU 51, the solenoid 72f is de-energized to control the opening / closing operation of the spill valve 72d and stopped in the open state, and the fuel pressurized to the feed pressure by the low-pressure feed pump 71 is increased in pressure. The spill valve 72d is opened and closed in a relatively quiet operation region such as the idling operation after the warm-up by supplying fuel to the fuel injection mechanism 73 at a feed pressure without further pressurization by the fuel pump 72. It is possible to reduce the operation noise accompanying the operation.

  Here, the pulsation reducing unit 82 provided in the bypass pipe 81 reduces the pressure pulsation of the fuel passing through the bypass pipe 81. More specifically, the pulsation reducing unit 82 sets the bypass-side passage length L1 from the suction port 72g of the high-pressure fuel pump 72 via the bypass pipe 81 to the bypass connection unit 81b from the discharge port 72h of the high-pressure fuel pump 72. It is configured by setting it longer than the high-pressure side passage length L2 of the high-pressure fuel supply pipe 75 up to one delivery pipe 76a. The bypass side passage length L1 is a total length of the bypass pipe 81 and the passage length of the low-pressure fuel supply pipe 74 from the bypass branch portion 81a to the suction port 72g of the high-pressure fuel pump 72. Thus, when the spill valve 72d is stopped in the open state and the feed pressure operation is performed, the fuel of the feed pressure passes through the bypass pipe 81 having a relatively long pipe length, thereby reducing the pressure pulsation of the fuel. Attenuation is caused by pressure loss, and this pressure pulsation is prevented from propagating to the fuel injection mechanism 73. On the other hand, when the spill valve 72d is operated and the high pressure fuel pump 72 pressurizes the fuel to the feed pressure or higher, the pressurized fuel has a relatively short pipe length and a small volume. By passing through 75, it is possible to prevent the time for increasing the pressure to an appropriate pressure from becoming long.

  Here, the pulsation cycle of the fuel accompanying the reciprocating motion of the plunger 72b changes according to the speed of the reciprocating motion of the plunger 72b, that is, the engine speed. The bypass side passage length L1 necessary for the attenuation of the pressure pulsation in the pulsation reducing unit 82 is proportional to the pulsation cycle, and the bypass side passage length becomes longer as the pulsation cycle becomes longer (lower the pulsation frequency). It is necessary to lengthen L1. In the present embodiment, the bypass-side passage length L1 is set to a length capable of attenuating pressure pulsation at least at an idling rotational speed (for example, 500 to 800 rpm) that is the lower limit rotational speed of the engine 10. If it is equal to or higher than the rotation speed, the pressure pulsation is attenuated, and propagation of the pulsation through the bypass pipe 81 can be prevented.

  Note that the fuel tank 70 of the present embodiment is disposed at the rear of the vehicle, and the engine 10 is disposed at the front of the vehicle. The bypass branch portion 81 a of the bypass pipe 81 is provided on the low pressure feed pump 71 side in the low pressure fuel supply pipe 74. That is, the bypass pipe 81 branches from the low-pressure feed pump 71 side in the low-pressure fuel supply pipe 74 from the middle of the low-pressure feed pump 71 and the high-pressure fuel pump 72, more specifically, from the vicinity of the outlet portion of the fuel tank 70. It is provided in parallel with the fuel supply pipe 74. As a result, the bypass pipe 81 that requires the predetermined bypass-side passage length L1 together with the low-pressure fuel supply pipe 74 is formed into a space having a sufficient length from the fuel tank 70 at the rear of the vehicle to the engine 10 at the front of the vehicle. It can be mounted and an appropriate bypass-side passage length L1 can be easily ensured.

  Further, the bypass passage check valve 83 is provided on the bypass connection portion 81 b side in the bypass pipe 81. That is, the bypass passage check valve 83 is closer to the bypass connection portion 81b side than the middle of the bypass branch portion 81a and the bypass connection portion 81b in the bypass pipe 81, more specifically, as close to the bypass connection portion 81b as possible. Provided. Thereby, the volume of the fuel supply path defined by the high pressure passage check valve 77, the high pressure side relief valve 80, and the bypass passage check valve 83 including the delivery pipe 76 and the connection pipe 78 can be minimized. It is possible to prevent the pressure increase rate when the fuel is pressurized to the feed pressure or higher by the high pressure fuel pump 72 from decreasing.

  According to the fuel supply device 1 of the engine 10 according to the embodiment of the present invention described above, the low-pressure feed pump 71 that can pressurize and feed fuel to a predetermined feed pressure, and is driven according to the operating state of the engine 10. The spill valve 72d opens and closes the intake port 72g to adjust the intake amount of fuel pressurized by the low pressure feed pump 71 and to pressurize and pump the pressurized fuel, and the pressurized fuel to the combustion chamber 18 A fuel injection mechanism 73 capable of injecting into the fuel, a low pressure fuel supply pipe 74 connecting the low pressure feed pump 71 and the high pressure fuel pump 72, a high pressure fuel supply pipe 75 connecting the high pressure fuel pump 72 and the fuel injection mechanism 73, A bypass pipe 81 having a bypass branch part 81a branched from the low-pressure fuel supply pipe 74 and a bypass connection part 81b connected to the fuel injection mechanism 73; And a pulsation reducing unit 82 for reducing pulsation of fuel, and a bypass passage reverse that prevents the reverse flow of fuel from the bypass connecting part 81b side to the bypass branching part 81a side and the valve opening pressure is set lower than the feed pressure. The stop valve 83 and the fuel injection mechanism 73 side prevent the back flow of fuel from the high pressure fuel pump 72 side, the valve opening pressure is higher than the feed pressure, and the fuel pulsation pressure accompanying the drive of the high pressure fuel pump 72 And a high-pressure passage check valve 77 set higher than that.

  Therefore, a bypass pipe 81 branched from the low-pressure fuel supply pipe 74 and a pulsation reducing unit 82 provided in the bypass pipe 81 are provided, and the valve opening pressure of the high-pressure passage check valve 77 is set higher than the feed pressure by the low-pressure feed pump 71. By setting it high, the fuel is pressurized by the high-pressure fuel pump 72 to a feed pressure or higher during normal operation, whereby the high-pressure passage check valve 77 is opened and the fuel is supplied via the high-pressure fuel supply pipe 75. High pressure fuel is supplied to the injection mechanism 73. When the pressurization by the high-pressure fuel pump 72 is stopped, the high-pressure passage check valve 77 is closed, the fuel supply to the fuel injection mechanism 73 through the high-pressure fuel supply pipe 75 is stopped, and the bypass pipe 81 is used. The fuel of the feed pressure is supplied to the fuel injection mechanism 73, and the feed pressure operation is started. At this time, since the fuel of the feed pressure passes through the bypass pipe 81 provided with the pulsation reducing unit 82, the pressure pulsation of the fuel is reduced, so that propagation of the fuel pressure pulsation generated by driving the high-pressure fuel pump 72 is effective. Can be suppressed.

  Furthermore, by setting the valve opening pressure of the bypass passage check valve 83 to be lower than the fuel feed pressure, it is possible to prevent the back flow of fuel from the bypass connection portion 81b side to the bypass branch portion 81a side. The fuel pressure supplied to 76 can be kept constant. When the fuel pressure in the bypass pipe 81 becomes the feed pressure, the valve is opened and the fuel at the feed pressure can be supplied to the delivery pipe 76.

  Further, by setting the valve opening pressure of the high pressure passage check valve 77 higher than the pulsation pressure of the fuel, the high pressure passage check valve 77 may be opened by the fuel pulsation pressure accompanying the reciprocating motion of the plunger 72b. Therefore, it is possible to prevent the pressure pulsation from propagating to the fuel injection mechanism 73 via the high-pressure fuel supply pipe 75 during the feed pressure operation.

  That is, by providing the bypass pipe 81 and appropriately setting the valve opening pressures of the high pressure passage check valve 77 and the bypass passage check valve 83, the fuel supply path can be switched according to the fuel pressure by a mechanical configuration. Therefore, it is possible to quickly shift to the feed pressure operation and to improve the reliability at low cost.

  Furthermore, according to the fuel supply device 1 for the engine 10 according to the embodiment of the present invention described above, the high-pressure fuel pump 72 reciprocates in conjunction with the rotation of the crankshaft 16 of the engine 10, thereby The plunger 72b that can suck and pressurize the fuel and pressurize and pump the fuel, and the spill valve 72d is opened to suck the fuel and close the valve to pressurize and pump the fuel. Therefore, in the high-pressure fuel pump 72, the plunger 72b reciprocates in conjunction with the rotation of the crankshaft 16 of the engine 10 and the spill valve 72d opens and closes, so that fuel can be sucked, pressurized and pumped. During the feed pressure operation, the pressurization of the fuel by the high-pressure fuel pump 72 can be stopped only by opening the spill valve 72d. During this time, the fuel reciprocating with the reciprocating motion of the plunger 72b can be stopped. Even if pressure pulsation occurs, the fuel is supplied to the fuel injection mechanism 73 via the bypass pipe 81, so that the pressure pulsation can be effectively suppressed.

  Furthermore, according to the fuel supply device 1 of the engine 10 according to the embodiment of the present invention described above, the pulsation reducing unit 82 is a bypass-side passage from the high-pressure fuel pump 72 to the bypass connection unit 81b via the bypass pipe 81. The length L1 is configured to be longer than the high-pressure side passage length L2 of the high-pressure fuel supply pipe 75. Therefore, by configuring the pulsation reducing unit 82 by making the bypass side passage length L1 longer than the high pressure side passage length L2, when performing feed pressure operation, a pipe with relatively long feed pressure fuel is used. Since it passes through the bypass pipe 81 having a path length, the pressure pulsation is attenuated by pressure loss, and the pressure pulsation can be prevented from propagating to the fuel injection mechanism 73, while the fuel is pressurized above the feed pressure. In this case, since the pressurized fuel passes through the high-pressure fuel supply pipe 75 having a relatively short pipe length and a small volume, it is possible to prevent the time for increasing the pressure to an appropriate pressure from becoming long. Can do.

  Furthermore, according to the fuel supply device 1 of the engine 10 according to the embodiment of the present invention described above, the bypass branch portion 81a is provided on the low pressure feed pump 71 side in the low pressure fuel supply pipe 74. Therefore, the bypass pipe 81 that requires a predetermined bypass side passage length L1 is mounted in a space having a sufficient length from the fuel tank 70 at the rear of the vehicle to the engine 10 at the front of the vehicle together with the low-pressure fuel supply pipe 74. And an appropriate bypass-side passage length L1 can be easily ensured. For this reason, it is not necessary to secure a new space for installing the bypass pipe 81 in the space between the high-pressure fuel pump 72 and the delivery pipe 76 or in a limited space near the engine 10, thereby improving space efficiency and manufacturing efficiency. Can be made.

  Furthermore, according to the fuel supply device 1 of the engine 10 according to the embodiment of the present invention described above, the bypass passage check valve 83 is provided on the bypass connection portion 81 b side in the bypass pipe 81. Therefore, the volume of the fuel supply path defined by the high pressure passage check valve 77, the high pressure side relief valve 80, and the bypass passage check valve 83 can be minimized, and the high pressure fuel pump 72 supplies the fuel to a pressure higher than the feed pressure. It is possible to prevent the pressure increase speed when the pressure is increased.

  Furthermore, according to the fuel supply device 1 of the engine 10 according to the embodiment of the present invention described above, the ECU 51 that controls the spill valve 72d to be in the open state when the operating state of the engine 10 is the idling state after the warm-up. Is provided. Therefore, during the idling operation after the warm-up, the spill valve 72d is stopped in the open state, and the fuel pressurized to the feed pressure by the low-pressure feed pump 71 is not further pressurized by the high-pressure fuel pump 72. By supplying the fuel injection mechanism 73 with the feed pressure, it is possible to reduce the operating noise associated with the opening and closing of the spill valve 72d in a relatively quiet operation region. During this time, in idling after warm-up, the engine coolant temperature is high, the fuel is relatively easy to vaporize and atomize, and since the rotation speed is low, the period from fuel injection to ignition is relatively long, and the in-cylinder pressure is also compared. Therefore, even when fuel is injected at a feed pressure, the fuel can be sufficiently vaporized and atomized.

  The fuel supply device 1 for an internal combustion engine according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the bypass passage backflow prevention means of the present invention has been described as configured by the bypass passage check valve 83 in which the valve opening pressure is set lower than the feed pressure, but the drive is controlled by the ECU 51. You may comprise by a bypass channel | path solenoid valve. In this case, the ECU 51 controls opening and closing of the bypass passage electromagnetic valve according to the fuel pressure in the delivery pipe 76 detected by the fuel pressure sensor 59. Thereby, compared with the case where the bypass passage backflow prevention means is configured by the bypass passage check valve 83, fuel pressure loss and fuel pressure fluctuation at the time of valve opening can be suppressed, and controllability of fuel pressure at the time of feed pressure operation is improved. can do. Further, by opening the bypass passage electromagnetic valve during normal (high pressure) operation, the fuel pressure can be reduced and the controllability of the fuel pressure is further improved.

  FIG. 3 is a schematic configuration diagram illustrating a fuel system of a fuel supply device for an internal combustion engine according to a second embodiment of the present invention. The fuel supply device for the internal combustion engine according to the second embodiment has substantially the same configuration as the fuel supply device for the internal combustion engine according to the first embodiment, but the embodiment is different in that the bypass passage and the high-pressure fuel return passage are shared. 1 is different from the fuel supply device for an internal combustion engine according to the first aspect. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 3, the fuel supply device 201 of the engine 10 according to the second embodiment includes a bypass pipe 281 as a bypass passage that branches from the low-pressure fuel supply pipe 74 and connects to the fuel injection mechanism 73. Specifically, the bypass pipe 281 has a bypass branch part 281 a that branches from the low-pressure fuel supply pipe 74 and a bypass connection part 281 b that connects to the second delivery pipe 76 b of the fuel injection mechanism 73. That is, the bypass pipe 281 is branched from the low pressure fuel supply pipe 74 at the bypass branch section 281a, and is connected to the second delivery pipe 76b at the bypass connection section 281b without passing through the high pressure fuel pump 72. is there. The bypass pipe 281 is provided with a bypass passage check valve 283 as a bypass passage backflow prevention means.

  The bypass branch portion 281a of the bypass pipe 281 is provided on the low-pressure feed pump 71 side in the low-pressure fuel supply pipe 74, similarly to the bypass branch portion 81a of the first embodiment described above. Further, the bypass passage check valve 283 has the same configuration as the bypass passage check valve 83 of the first embodiment and is provided on the bypass connection portion 281b side in the bypass pipe 281. The pulsation reducing unit 282 as a pulsation reducing unit provided in the bypass pipe 281 is also connected by bypass from the suction port 72g of the high-pressure fuel pump 72 via the bypass pipe 281, similarly to the pulsation reducing unit 82 of the first embodiment. The bypass side passage length L1 to the portion 281b is set longer than the high pressure side passage length L2 of the high pressure fuel supply pipe 75 from the discharge port 72h of the high pressure fuel pump 72 to the first delivery pipe 76a.

  On the other hand, the fuel supply apparatus 201 of the present embodiment does not include the high-pressure fuel return pipe 79 (see FIG. 1) described in the first embodiment. Instead, the bypass pipe 281 is replaced with the first delivery pipe 76a and the second delivery pipe 76a. The pipe 76b is also used as a passage for returning surplus fuel to the fuel tank 70. That is, a high-pressure relief valve 280 as a high-pressure adjusting valve is mounted in the vicinity of the bypass connection portion 281b of the bypass pipe 281.

  The high-pressure relief valve 280 is provided in a branch pipe 280 a that branches from the bypass pipe 281, bypasses the bypass passage check valve 283, and is connected to the bypass pipe 281 again. That is, the bypass passage check valve 283 and the high-pressure relief valve 280 are provided in parallel in the bypass pipe 281. The high-pressure side relief valve 280 opens when the high-pressure fuel in the first delivery pipe 76a and the second delivery pipe 76b reaches a predetermined pressure, for example, about a dozen MPa or more, so that the fuel pressure exceeds the predetermined pressure. When it becomes higher, surplus fuel in the first delivery pipe 76 a and the second delivery pipe 76 b is discharged to the bypass pipe 281. The surplus fuel is returned to the fuel tank 70 via the bypass pipe 281, the low pressure fuel supply pipe 74, the low pressure fuel return pipe 74 a and the low pressure side relief valve 74 b, whereby the first delivery pipe 76 a and the second delivery pipe 76 a. The fuel pressure in the pipe 76b can be kept constant.

  According to the fuel supply device 201 of the engine 10 according to the embodiment of the present invention described above, the high-pressure relief valve 280 that discharges excess fuel of the fuel injection mechanism 73 to the bypass pipe 281 is provided. Therefore, by providing the bypass pipe 281 with the bypass passage check valve 283 and the high-pressure relief valve 280 that discharges excess fuel from the fuel injection mechanism 73, feed pressure fuel is supplied to the fuel injection mechanism 73 via the bypass pipe 281. The surplus fuel in the fuel injection mechanism 73 can be discharged to the bypass pipe 281, and the bypass pipe 281 can be shared as a passage for returning the surplus fuel in the fuel injection mechanism 73 to the fuel tank 70. As a result, the number of pipes provided in the fuel supply apparatus 201 can be reduced, the fuel supply apparatus 201 can be made more compact and have a smaller number of parts, and the manufacturing cost can be reduced.

  FIG. 4 is a schematic configuration diagram showing a fuel system of a fuel supply device for an internal combustion engine according to Embodiment 3 of the present invention. The fuel supply device for the internal combustion engine according to the third embodiment has substantially the same configuration as the fuel supply device for the internal combustion engine according to the second embodiment, but the configuration of the bypass passage flow preventing means is the fuel for the internal combustion engine according to the second embodiment. Different from the feeding device. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 4, the fuel supply device 301 of the engine 10 according to the third embodiment replaces the high-pressure side relief valve 280 (see FIG. 3) and the bypass passage check valve 283 (see FIG. 3) of the second embodiment. In addition, an electromagnetic relief valve 383 is provided as bypass passage flow preventing means whose driving is controlled by the ECU 51. Specifically, the electromagnetic relief valve 383 includes a valve body 383a, a solenoid 383b, a spring 383c, and a casing 383d for housing them.

  The valve body 383a can open and close the bypass pipe 281. The valve body 383a is biased in the direction in which the bypass pipe 281 can be closed by the spring 383c, in this case, in the direction away from the second delivery pipe 76b by the solenoid 383b, while being biased in the direction of the second delivery pipe 76b on the high pressure side. By applying a suction force, the bypass pipe 281 can be opened and closed. The solenoid 383b is electrically connected to the ECU 51, and energization thereof is controlled by a control signal transmitted from the ECU 51.

  That is, the electromagnetic relief valve 383 is a normally closed valve, and when the solenoid 383b is in a non-energized state, the spring 383c biases the valve body 383a in the direction of the second delivery pipe 76b, thereby bypass pipe. While the solenoid 383b is energized while the solenoid 383 is closed, a suction force is applied to the valve body 383a in a direction away from the second delivery pipe 76b, whereby the bypass pipe 281 is opened.

  Further, here, the biasing force of the spring 383c is the biasing force that opens the valve body 383a when the high-pressure fuel in the first delivery pipe 76a and the second delivery pipe 76b reaches a predetermined pressure, for example, about a dozen MPa or more. Is set.

  That is, the ECU 51 normally controls opening and closing of the electromagnetic relief valve 383 according to the fuel pressure in the delivery pipe 76 detected by the fuel pressure sensor 59. Thereby, for example, as compared with the case where the bypass passage backflow prevention means is configured by the bypass passage check valve 83 (see FIG. 1) as in the first embodiment, fuel pressure loss and fuel pressure fluctuation at the time of valve opening are suppressed. It is possible to improve the controllability of the fuel pressure during the feed pressure operation. Further, by opening the bypass passage electromagnetic valve during normal (high pressure) operation, the fuel pressure can be reduced and the controllability of the fuel pressure is further improved. On the other hand, even if the wiring connected to the electromagnetic relief valve 383 is disconnected and the energization control of the solenoid 383b becomes impossible, the urging force of the spring 383c is set as described above. When the pressure becomes higher than the predetermined pressure, the electromagnetic relief valve 383 is opened and the surplus fuel is returned to the fuel tank 70 via the bypass pipe 281, and the fuel pressure in the first delivery pipe 76a and the second delivery pipe 76b is reduced. Can be kept constant. The urging force of the spring 383c may be set in consideration of the pressure receiving area of the valve body 383a.

  According to the fuel supply device 301 of the engine 10 according to the embodiment of the present invention described above, the bypass passage flow preventing means of the present invention is an electromagnetic relief valve that discharges surplus fuel of the fuel injection mechanism 73 to the bypass pipe 281. 383. Therefore, by providing the electromagnetic relief valve 383 in the bypass pipe 281, the fuel at the feed pressure can be supplied to the fuel injection mechanism 73 via the bypass pipe 281, and surplus fuel in the fuel injection mechanism 73 is supplied to the bypass pipe 281. The bypass pipe 281 can be shared as a passage that can be discharged and returns surplus fuel in the fuel injection mechanism 73 to the fuel tank 70. As a result, the number of pipes provided in the fuel supply device 201 can be reduced. For example, since it is not necessary to provide the branch pipe 280a as in the second embodiment, the fuel supply device 201 is more compact and has a smaller number of parts. And can contribute to a reduction in manufacturing cost.

  Further, even if the wiring connected to the electromagnetic relief valve 383 is disconnected and the energization control of the solenoid 383b becomes impossible, when the fuel pressure becomes higher than a predetermined pressure, the electromagnetic relief valve 383 Since the valve is opened and the fuel pressure in the first delivery pipe 76a and the second delivery pipe 76b can be kept constant, appropriate safety can be ensured.

  FIG. 5 is a schematic configuration diagram illustrating a fuel system of a fuel supply device for an internal combustion engine according to a fourth embodiment of the present invention. The fuel supply device for the internal combustion engine according to the fourth embodiment has substantially the same configuration as the fuel supply device for the internal combustion engine according to the first embodiment, but the fuel supply device for the internal combustion engine according to the first embodiment has a configuration of pulsation reducing means. Is different. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 5, in the fuel supply device 401 of the engine 10 according to the fourth embodiment, a pulsation reducing unit 482 serving as a pulsation reducing unit is provided in a bypass pipe 481 serving as a bypass passage. Here, the bypass branch portion 81a of the bypass pipe 81 (see FIG. 1) in the first embodiment is provided on the low-pressure feed pump 71 side in the low-pressure fuel supply pipe 74 in order to ensure an appropriate bypass-side passage length L1. In contrast, the bypass branch portion 481a of the bypass pipe 481 in the fourth embodiment may be provided anywhere on the low-pressure fuel supply pipe 74, and is provided on the high-pressure fuel pump 72 side here. Thereby, the fuel supply apparatus 401 can be made more compact.

  And although the pulsation reduction part 82 (refer FIG. 1) of Example 1 was comprised by setting the bypass side channel | path length L1 longer than the high voltage | pressure side channel | path length L2, it is different from Example 4's. In the fuel supply device 401, the pulsation reducing unit 482 includes a throttle unit 482a provided in the bypass pipe 481 and a pulsation damper 482b as an attenuator provided in the bypass pipe 481.

  The restricting portion 482a restricts the area of the fuel passage in the bypass pipe 481, and is formed by reducing the inner diameter of the bypass pipe 481. The pulsation damper 482b is provided closer to the bypass connection part 481b than the throttle part 482a of the bypass pipe 481, and has a diaphragm. When the fuel of the feed pressure introduced into the bypass pipe 481 reaches the throttle portion 482a, the flow passage area is reduced, so that resistance is generated when passing through the throttle portion 482a, thereby reducing pressure pulsation. Is done. When the pulsation damper 482b is reached, the pressure pulsation is further attenuated by the diaphragm.

  According to the fuel supply device 401 of the engine 10 according to the embodiment of the present invention described above, the pulsation reducing unit 482 includes the throttle unit 482a that reduces the fuel passage area, and the pulsation damper 482b that attenuates the fuel pulsation. Have Therefore, by providing the bypass pipe 481 with the throttle portion 482a and the pulsation damper 482b, when the fuel is supplied to the fuel injection mechanism 73 via the bypass pipe 81 during the feed pressure operation, the fuel is restricted to the throttle portion 482a. A resistance is generated when passing through the valve, whereby the pressure pulsation is reduced, and when the pressure reaches the pulsation damper 482b, the diaphragm further attenuates the pressure pulsation. Further, for example, since it is not necessary to increase the bypass side passage length L1 as in the first embodiment, the fuel supply device 401 can be configured more compactly.

  Here, the pulsation reducing unit 482 may be configured by only one of the throttle unit 482a and the pulsation damper 482b, or a plurality of the pulsation reducing units 482 are not necessarily provided. However, when the pulsation reducing unit 482 is configured by providing each one of the throttle unit 482a and the pulsation damper 482b as described above, the pressure pulsation can be sufficiently attenuated while maintaining an appropriate flow rate of fuel, The pulsation damper 482b is most preferable because it can be compact.

  The fuel supply device for an internal combustion engine according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the fuel supply device 1, 201, 301, 401 of the present invention is applied to the in-cylinder injection type 6-cylinder engine. However, the present invention is not limited to this type of engine. The present invention can also be applied, and the same effects can be obtained even when applied to a port injection engine or the like provided with an injector capable of injecting fuel into the intake port 19 communicating with the combustion chamber 18.

  In the above description, the delivery pipe 76 has been described as being configured by the first delivery pipe 76a and the second delivery pipe 76b. However, the present invention is not limited to this, and may be one or three or more. In the above description, the bypass passage is described as being connected to the first delivery pipe 76a or the second delivery pipe 76b, but the downstream side of the high pressure passage check valve 77 of the high pressure passage (the fuel injection mechanism 73 side). You may make it connect to. That is, the bypass connection portion may be provided on the downstream side of the high pressure passage check valve 77 of the high pressure passage.

  In the above description, the ECU 51 has been described as executing the feed pressure operation during the idling operation after warming up. However, the present invention is not limited to this. A feed pressure operation may be executed.

  In the above description, the fuel tank 70 is disposed at the rear of the vehicle and the engine 10 is disposed at the front of the vehicle. Further, the pulsation reducing means is not limited to the above configuration, and an accumulator or the like may be used, or a combination thereof.

  As described above, the fuel supply device for an internal combustion engine according to the present invention effectively suppresses propagation of fuel pressure pulsation, and is suitable for use in various internal combustion engines in which fuel pressure pulsation is generated by driving a high-pressure pump. is there.

1 is a schematic configuration diagram showing a fuel system of a fuel supply device for an internal combustion engine according to Embodiment 1 of the present invention. 1 is a schematic configuration diagram illustrating an engine to which a fuel supply device for an internal combustion engine according to a first embodiment of the present invention is applied. It is a schematic block diagram which shows the fuel system of the fuel supply apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a schematic block diagram which shows the fuel system of the fuel supply apparatus of the internal combustion engine which concerns on Example 3 of this invention. It is a schematic block diagram which shows the fuel system of the fuel supply apparatus of the internal combustion engine which concerns on Example 4 of this invention.

Explanation of symbols

1, 201, 301, 401 Fuel supply device 10 Engine 18 Combustion chamber 70 Fuel tank 71 Low pressure feed pump (low pressure pump)
72 High Pressure Fuel Pump (High Pressure Pump)
72a Casing 72b Plunger 72c Pressure chamber 72d Spill valve 72g Suction port 72h Discharge port 73 Fuel injection mechanism (fuel injection means)
74a Low pressure fuel return pipe 74b Low pressure relief valve 74 Low pressure fuel supply pipe (low pressure passage)
75 High pressure fuel supply pipe (high pressure passage)
76 Delivery pipe 76a First delivery pipe 76b Second delivery pipe 77 High pressure passage check valve 79 High pressure fuel return pipe 80, 280 High pressure side relief valves 81, 281, 481 Bypass pipe (bypass passage)
81b, 281b, 481b Bypass connection parts 81a, 281a, 481a Bypass branch parts 82, 282, 482 Pulsation reducing part (pulsation reducing means)
83, 283 Bypass passage check valve (Bypass passage backflow prevention means)
383 Electromagnetic relief valve 482b Pulsation damper (attenuator)
482a Aperture part

Claims (10)

A low-pressure pump capable of pressurizing and feeding fuel to a predetermined feed pressure;
A high-pressure pump that is driven according to the operating state of the internal combustion engine, and that adjusts the intake amount of the fuel pressurized by the low-pressure pump by opening and closing the intake port of the metering valve, and that can be pressurized and pumped;
Fuel injection means capable of injecting the pressurized fuel into a combustion chamber or an intake port communicating with the combustion chamber;
A low-pressure passage connecting the low-pressure pump and the high-pressure pump;
A high-pressure passage connecting the high-pressure pump and the fuel injection means;
A bypass passage having a bypass branch portion branched from the low pressure passage and a bypass connection portion connected to the high pressure passage or the fuel injection means;
Pulsation reducing means provided in the bypass passage for reducing pulsation of fuel;
Bypass passage backflow prevention means for preventing the backflow of fuel from the bypass connection portion side to the bypass branch portion side and the valve opening pressure is set lower than the feed pressure;
The reverse flow of fuel from the fuel injection means side to the high pressure pump side is prevented, and the valve opening pressure is set higher than the feed pressure and higher than the fuel pulsation pressure accompanying the driving of the high pressure pump. A high-pressure passage check valve,
A fuel supply device for an internal combustion engine. The high-pressure pump has a plunger that can reciprocate in conjunction with the rotation of the crankshaft of the internal combustion engine to suck in fuel from the suction port, pressurize the pump, and open the metering valve. It is characterized by pressurizing and pumping by inhaling fuel and closing the valve,
The fuel supply device for an internal combustion engine according to claim 1. The pulsation reducing means is configured by setting a bypass side passage length from the high pressure pump through the bypass passage to the bypass connection part longer than a high pressure side passage length of the high pressure passage. To
The fuel supply device for an internal combustion engine according to claim 1 or 2. The pulsation reducing means includes a throttle portion that restricts a passage area of the fuel, and an attenuator that attenuates the pulsation of the fuel.
The fuel supply device for an internal combustion engine according to claim 1 or 2. The bypass branch is provided on the low pressure pump side in the low pressure passage,
The fuel supply device for an internal combustion engine according to any one of claims 1 to 4. The bypass passage backflow prevention means is provided on the bypass connection portion side in the bypass passage,
The fuel supply device for an internal combustion engine according to any one of claims 1 to 5. The bypass passage backflow prevention means is constituted by a solenoid valve,
The fuel supply device for an internal combustion engine according to any one of claims 1 to 6. It is provided with a relief valve that discharges surplus fuel of the fuel injection means to the bypass passage,
The fuel supply device for an internal combustion engine according to any one of claims 1 to 7. The bypass passage flow preventing means is constituted by an electromagnetic relief valve that discharges excess fuel of the fuel injection means to the bypass passage.
The fuel supply device for an internal combustion engine according to any one of claims 1 to 6. When the operating state of the internal combustion engine is an idling state after warming-up, it comprises control means for controlling the metering valve to an open state.
The fuel supply device for an internal combustion engine according to any one of claims 1 to 9.

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