Fuel injection device and engine

Abstract

To suppress variation in fuel injection into each cylinder by stabilizing a fuel pressure inside a fuel pressure accumulation pipe when injecting fuel from an injector to each cylinder.SOLUTION: A fuel injection device 5 includes: a first injector 231 and a second injector 232; a fuel pressure accumulation pipe 23 for accumulating pressure of fuel; a fuel pump 61 for pressure-sending the fuel into the fuel pressure accumulation pipe 23; a cam 62 having a cam profile 620 for driving the fuel pump 61 at predefined timing; and a control part 4 for controlling injection of the fuel. The control part 4 controls timing of main injection of the fuel by the injectors and prior injection that is executed prior to the main injection. The cam 62 has the cam profile 620 that completes sending, to the fuel pressure accumulation pipe 23, the fuel of an amount to be supplied to all cylinders in a period from the end of the latest main injection to the start of the earliest prior injection among the fuel injections from the injectors within one cycle.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fuel injection device and an engine. [Background technology]

[0002] 2. Description of the Related Art A known fuel injection device for engine fuel injection sends fuel under pressure to a fuel accumulator pipe, such as a rail or a holder, and injects the fuel accumulated in the fuel accumulator pipe from an injector into a cylinder at a predetermined timing.

[0003] Patent Document 1 discloses an electronically controlled fuel injection device for a diesel engine, which includes an injection pump that sucks in and pumps out fuel by reciprocating a plunger with the rotation of a cam, and an electromagnetic spill valve, and which controls fuel injection by controlling the opening and closing of the electromagnetic spill valve.The electronically controlled fuel injection device forms a cam profile on the outer periphery of the cam, which has a first constant speed region in which the sliding speed of the plunger in the compression direction is constant, and a second constant speed region in which the sliding speed is faster than the first constant speed region, and performs pilot injection in the first constant speed region and main injection in the second constant speed region by opening and closing the electromagnetic spill valve.

[0004] Patent Document 2 discloses a fuel injection system including a pressure accumulator that accumulates fuel, a cylinder having a pressure chamber formed therein, a plunger that performs a pressurizing movement, which is a movement in a pressurizing direction within the cylinder, and pressure-feeds fuel to the pressure accumulator by causing a volume change within the pressure chamber by the pressurizing movement, an injection unit having an injector that injects the fuel accumulated in the pressure accumulator, and a control unit that controls the injection amount of fuel from the injector, wherein the control unit has a pumping amount calculation unit that calculates the amount of fuel pumped to the pressure accumulator during an injection period of fuel from the injector, and a correction amount determination unit that determines a correction amount for the injection period based on the pumping amount during the injection period, and the pumping amount calculation unit estimates the amount of fuel leaking from a gap between an inner circumferential surface of the pressure chamber and an outer circumferential surface of the plunger, and calculates the pumping amount using the estimated leakage amount and an amount of volume change within the pressure chamber corresponding to the stroke of the plunger during the pressurizing movement.

[0005] Patent Document 3 discloses a diesel engine having a main combustion chamber and a secondary combustion chamber connected to the main combustion chamber, the diesel engine comprising: an injector facing the secondary combustion chamber for injecting fuel into the secondary combustion chamber; a control device for controlling the injection timing of the fuel injected from the injector; and exhaust gas recirculation means for recirculating exhaust gas from the engine, the control device controlling the injection timing of a main injection and a pre-injection performed prior to the main injection, and generating a homogeneous and lean pre-mixture of the fuel injected in the pre-injection and the air in the secondary combustion chamber by ensuring a pre-mixing period of the pre-injection from the start of the pre-injection until the mixture of the fuel injected in the pre-injection and the air is ignited, and executing control to ensure the pre-mixing period of the main injection from the start of the main injection until the mixture of the fuel injected in the main injection and the air is ignited.

[0006] When a fuel injection device using such a fuel accumulator is applied to a multi-cylinder engine, it is necessary to stably inject fuel from the injector for each cylinder. Therefore, it is important to suppress and stabilize the occurrence of variations in fuel pressure (such as pressure pulsation) inside the fuel accumulator by not pumping fuel to the fuel accumulator at the timing when fuel is injected from the injector.

[0007] Meanwhile, in order to reduce soot, NOx, and other emissions from the fuel injection from the injector to each cylinder, pilot injection may be performed before the main injection. In recent years, ultra-early pilot injection has also been performed to more effectively suppress the generation of soot, NOx, and other emissions. In fuel injection control that includes such ultra-early pilot injection, the period between fuel injection in one cylinder and fuel injection in the next cylinder within one cycle of the engine, which includes intake, compression, explosion, and exhaust, becomes extremely short. This makes it difficult to stabilize the fuel pressure in the fuel accumulator pipe by the time of fuel injection. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2008-215147 A [Patent Document 2] JP 2012-163056 A [Patent Document 3] JP 2023-086427 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a fuel injection device and an engine that can stabilize the fuel pressure in a fuel accumulator pipe when fuel is injected from an injector to each cylinder, thereby suppressing variation in fuel injection to each cylinder. [Means for solving the problem]

[0010] A first aspect of the present invention is a fuel injection device used in a four-stroke, one-cycle, multi-cylinder engine, comprising: a plurality of injectors that inject the fuel into each of the cylinders; a fuel accumulator pipe that accumulates the fuel to be supplied to the plurality of injectors; a fuel pump that pressure-feeds the fuel to the fuel accumulator pipe; a cam that rotates based on rotation of a crankshaft and has a cam profile for driving the fuel pump at a predetermined timing; and a control unit that controls injection of the fuel by each of the plurality of injectors, wherein the control unit controls timing of a main injection of the fuel by the injectors and a pre-injection that is performed prior to the main injection, and the cam has the cam profile that completes sending to the fuel accumulator pipe an amount of the fuel to be supplied to all of the cylinders during a period from after the latest main injection to before the start of the earliest pre-injection among the injections of the fuel from the injectors in one cycle.

[0011] A second aspect of the present invention is a four-stroke, one-cycle, multi-cylinder engine equipped with a fuel injection device that injects fuel into each cylinder, the fuel injection device comprising: a plurality of injectors that inject the fuel into each of the cylinders, a fuel accumulator pipe that accumulates the fuel to be supplied to the plurality of injectors, a fuel pump that pressure-feeds the fuel to the fuel accumulator pipe, a cam that rotates based on rotation of a crankshaft and has a cam profile for driving the fuel pump at a predetermined timing, and a control unit that controls injection of the fuel by each of the plurality of injectors, wherein the control unit controls timing of a main injection of the fuel by the injectors and a pre-injection that is performed prior to the main injection, and the cam has the cam profile that completes sending to the fuel accumulator pipe an amount of the fuel to be supplied to all of the cylinders during a period from after the latest main injection to before the start of the earliest pre-injection among the injections of the fuel from the injectors in one cycle. Effect of the Invention

[0012] According to the present invention, it is possible to provide a fuel injection device and an engine that can stabilize the fuel pressure inside the fuel accumulator pipe when injecting fuel from the injector to each cylinder, thereby suppressing variation in fuel injection to each cylinder. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an engine according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view illustrating a fuel injection device according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a perspective view illustrating a fuel pump and a cam. [Figure 4] FIG. [Diagram 5] FIG. 13 is a front view illustrating a cam profile. [Figure 6] 4 is a diagram illustrating an example of a cam lift amount with respect to a crank rotation angle; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiments described below are preferred specific examples of the present invention, and therefore various technically preferable limitations are applied to them, but the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is limited to them. In addition, in each drawing, similar components are given the same reference numerals, and detailed descriptions thereof are omitted as appropriate.

[0015] In this specification, the rotation angle of the crankshaft is also referred to as the "crank rotation angle," and the rotation angle of the camshaft having the cam 62 (see FIG. 2) is also referred to as the "cam rotation angle." The unit of the rotation angle is degree, and it is expressed in "degrees" or "°."

[0016] (engine) FIG. 1 is a schematic diagram illustrating an engine according to this embodiment. The engine 2 according to this embodiment is a four-stroke, one-cycle internal combustion engine, and is a small naturally aspirated engine. The engine 2 shown in FIG. 1 is an in-line two-cylinder engine. The displacement of the engine 2 is about 500 cc. Note that the displacement is not limited to about 500 cc. The timing difference between the combustion stroke of the first cylinder 241, which is one of the two cylinders, and the combustion stroke of the second cylinder 242, which is the other, is, for example, 180 degrees in terms of the crankshaft angle. The engine 2 according to this embodiment does not include a turbocharger for supercharging.

[0017] As shown in FIG. 1, the engine 2 includes an intake manifold 22, a cylinder block 24, and an exhaust manifold 25. The intake manifold 22 is connected to the intake pipe 21 and a cylinder head (not shown), and includes a first branch pipe 221 and a second branch pipe 222. The cylinder block 24 includes a first cylinder 241 and a second cylinder 242. The first cylinder 241 is connected to the first branch pipe 221 via an intake port (not shown) of the cylinder head. The second cylinder 242 is connected to the second branch pipe 222 via an intake port of the cylinder head. The exhaust manifold 25 is connected to the cylinder head and an exhaust pipe 26. Specifically, the exhaust manifold 25 is connected to the first cylinder 241 and the second cylinder 242 via an exhaust port of the cylinder head. The exhaust pipe 26 is included in an exhaust gas recirculation device 3, which will be described later.

[0018] Furthermore, engine 2 includes fuel accumulator pipe 23, first injector 231, and second injector 232. Fuel accumulator pipe 23 is formed in a cylindrical shape, and distributes fuel pressure-fed from a fuel pump 61 (see FIG. 2), which will be described later, to a plurality of paths according to the number of cylinders of engine 2. That is, fuel accumulator pipe 23 is a holder or a rail, and accumulates the fuel pressure-fed from the fuel pump, and supplies the high-pressure fuel to first injector 231 and second injector 232.

[0019] First injector 231 is attached to fuel accumulator pipe 23 and provided so as to protrude toward a combustion chamber formed in an upper part of first cylinder 241. First injector 231 opens and closes a needle valve, for example, by a solenoid, based on a signal transmitted from control unit 4, and injects fuel supplied from fuel accumulator pipe 23 from an injection hole (not shown) into the combustion chamber formed in an upper part of first cylinder 241. An example of control unit 4 is an electronic control unit (ECU).

[0020] The second injector 232 is attached to the fuel accumulator pipe 23 and is provided so as to protrude toward a combustion chamber formed in an upper part of the second cylinder 242. The second injector 232 opens and closes a needle valve, for example, by a solenoid based on a signal sent from the control unit 4, and injects the fuel supplied from the fuel accumulator pipe 23 from an injection hole into the combustion chamber formed in an upper part of the second cylinder 242.

[0021] The fuel pressure inside the fuel accumulator pipe 23 may be measured by a pressure sensor 55 attached to the fuel accumulator pipe 23. In this case, the pressure sensor 55 measures the fuel pressure inside the fuel accumulator pipe 23, and outputs a signal related to the fuel pressure to the control unit 4.

[0022] As indicated by an arrow A1 in Fig. 1, fresh intake air (i.e., intake air (also called outside air)) passes through the intake pipe 21, passes through an air cleaner 211 provided in the intake pipe 21, and is led to the intake manifold 22. The intake pipe 21 is a component included in the engine 2, and is also a component included in the exhaust gas recirculation device 3. The intake air led to the intake manifold 22 is distributed to a first branch pipe 221 and a second branch pipe 222, is led to a first cylinder 241 through the first branch pipe 221, and is led to a second cylinder 242 through the second branch pipe 222.

[0023] The exhaust gas discharged from the first cylinder 241 and the second cylinder 242 passes through the exhaust manifold 25 and is guided to the exhaust pipe 26. The exhaust gas guided to the exhaust pipe 26 passes through a diesel oxidation catalyst (DOC) 261, which is a purification unit provided in the exhaust pipe 26. At this time, the diesel oxidation catalyst 261 oxidizes SOF (soluble organic fraction), CO (carbon monoxide), and HC (hydrocarbon) in PM (particulate matter) contained in the exhaust gas. As indicated by an arrow A2 in FIG. 1, the exhaust gas that has passed through the diesel oxidation catalyst 261 passes through the exhaust discharge pipe 29 and is discharged to the outside of the engine 2. The diesel oxidation catalyst 261 is included in the exhaust gas recirculation device 3.

[0024] (Exhaust Gas Recirculation System) The engine 2 is equipped with an exhaust gas recirculation device 3. The exhaust gas recirculation device 3 recirculates a portion of the exhaust gas flowing through the exhaust system of the engine 2 to the intake system of the engine 2 as exhaust recirculation gas, thereby reducing nitrogen oxides (NOx) contained in the exhaust gas.

[0025] The exhaust gas recirculation device 3 according to this embodiment has an exhaust pipe 26, a diesel oxidation catalyst 261, an exhaust gas recirculation pipe 27, an exhaust gas discharge pipe 29, and a branching section 32. The rear stage of the diesel oxidation catalyst 261 is branched by the branching section 32 into an exhaust gas recirculation pipe 27 side and an exhaust gas discharge pipe 29 side. The exhaust gas recirculation pipe 27 is a pipe that guides exhaust gas recirculation gas, which is a part of the exhaust gas branched by the branching section 32, to the intake manifold 22 side. The exhaust gas discharge pipe 29 is a pipe that guides the remaining part of the exhaust gas branched by the branching section 32 to an exhaust port. The exhaust gas recirculation pipe 27 is provided with a flow rate adjustment means 28. The flow rate adjustment means 28 is called, for example, an EGR valve. The flow rate adjustment means 28 adjusts the flow rate of the exhaust gas recirculation gas flowing through the exhaust gas recirculation pipe 27 based on a signal transmitted from the control section 4.

[0026] Furthermore, the engine 2 has a control unit 4, a rotation sensor 51, a NOx sensor 53, a temperature sensor 54, a water temperature sensor 56, and an accelerator opening sensor (not shown). The engine 2 also has various other sensors such as a cam angle sensor 52. The control unit 4 performs calculations based on signals from the various sensors, and controls the fuel injection by the first injector 231 and the second injector 232, as well as controls the flow rate of the exhaust recirculation gas by the flow rate adjustment means 28.

[0027] (Fuel injection device) FIG. 2 is a perspective view illustrating the fuel injection device according to the present embodiment. FIG. 3 is a perspective view illustrating the fuel pump and the cam. 1, the fuel injection device 5 is a device that injects fuel into each cylinder (first cylinder 241 and second cylinder 242) of the engine 2. The fuel injection device 5 includes a fuel pump 61 and a cam 62 in addition to the multiple injectors (first injector 231, second injector 232), the fuel accumulator pipe 23, and the control unit 4 described above.

[0028] Fuel pump 61 pressure-feeds fuel to fuel accumulator pipe 23 by the reciprocating movement of plunger 611. The fuel pressure-feed from fuel pump 61 by the reciprocating movement of plunger 611 is sent to fuel accumulator pipe 23 through pressure-feed pipe 612. Plunger 611 abuts against cam 62, and moves back and forth according to the shape of the cam lobe (cam profile 620) as cam 62 rotates.

[0029] The cam 62 rotates based on the rotation of the crankshaft. In this embodiment, the rotation speed of the crankshaft is reduced by a plurality of gears and transmitted to the cam 62. Specifically, the speed is reduced by the crank gear 71, the idle gear 72, and the cam gear 73 so that the cam 62 rotates once (cam rotation angle 360°) for two rotations of the crankshaft (crank rotation angle 720°). Note that the mechanism for transmitting the rotation of the crankshaft to the cam 62 is not limited to gears, and may be a belt or a chain. Two rotations of the crank correspond to one cycle of the engine 2, so that the cam profile 620 for one revolution corresponds to the drive timing of the plunger 611 in one cycle.

[0030] The fuel accumulator pipe 23 may be provided with a regulator valve 233 for regulating the fuel pressure in the pipe and an emergency valve 234 that opens when the fuel pressure exceeds a certain level. The fuel released from the regulator valve 233 and the like and the fuel that overflows from the fuel pump 61 are returned to a fuel tank (not shown) through a return pipe 613.

[0031] (cam) FIG. 4 is a perspective view illustrating the cam. FIG. 5 is a front view illustrating a cam profile. 4 and 5, the cam 62 used in the fuel injection device 5 according to this embodiment has two cam lobes (a first cam lobe 621 and a second cam lobe 622) in one revolution of the cam profile 620. In this embodiment, the shape of the first cam lobe 621 and the shape of the second cam lobe 622 are the same, but the shapes and maximum cam heights of the first cam lobe 621 and the second cam lobe 622 may be different as necessary.

[0032] In this embodiment, the rotation angle difference θ between the apex V1 of the first cam lobe 621 and the apex V2 of the second cam lobe 622 is 120° in terms of the rotation angle around the rotation axis of the cam 62. That is, the position of the apex V1 of the first cam lobe 621 and the position of the apex V2 of the second cam lobe 622 are asymmetric with respect to the rotation axis of the cam 62. Therefore, the cam 62 drives (pumps) the plunger 611 (see FIG. 3) twice during a cam rotation angle of 120° (crank rotation angle of 240°), and does not drive or pump the plunger 611 during the remaining cam rotation angle of 240° (crank rotation angle of 480°). When pumping is not performed, the plunger 611 draws in fuel.

[0033] (Fuel injection and fuel pumping) FIG. 6 is a diagram illustrating an example of the cam lift amount with respect to the crank rotation angle. In FIG. 6, the horizontal axis indicates the crank rotation angle (0° to 720° (2 rotations)), and the vertical axis indicates the cam lift amount (the driving amount of the plunger 611 (see FIG. 3)) by the cam 62 (see FIG. 5) applied in this embodiment. The crank rotation angle values ​​shown in FIG. 6 are relative values ​​with the start position of the first cam lobe 621 of the cam 62 set to 0°. The crank rotation angle of 0° to 720° (2 rotations) shown on the horizontal axis of FIG. 6 corresponds to the cam rotation angle of the cam 62 of 0° to 360° (1 rotation). The cam lift amount during continuous operation of the engine 2 is a repetition of the cam lift amount corresponding to the crank rotation angle of 0° to 720° shown in FIG. 6. FIG. 6 also indicates the timing of fuel injection of the first injector 231 and the second injector 232 (see FIG. 1) with respect to the crank rotation angle (0 to 720°).

[0034] The control unit 4 (see FIG. 1) controls fuel injection by the first injector 231 and the second injector 232 (see FIG. 1 and FIG. 2) to perform multi-stage injection by dividing the fuel injection into a plurality of times during one cycle. Specifically, the control unit 4 performs a main injection and a pilot injection in which an injection amount of fuel smaller than the injection amount in the main injection is injected before the main injection during one cycle. The pilot injection of this embodiment is an example of the "pre-injection" of the present invention. Note that the "pre-injection" of the present invention is not limited to pilot injection, and may be pre-injection or may include both pilot injection and pre-injection. In the following description, a case where the pre-injection is pilot injection will be taken as an example.

[0035] In the engine 2 according to this embodiment, the strokes of each cylinder are offset by 180 degrees in crank rotation angle (90 degrees in cam rotation angle) from each other, so the states of the first cylinder 241 and the second cylinder 242 at each stroke are as follows: (First stroke) When the crank rotation angle is 0° (720°) or more and less than 180° (on the horizontal axis shown in Figure 6, 212° or more and less than 392°) Intake stroke of the first cylinder 241 + exhaust stroke of the second cylinder 242 (2nd stroke) When the crank rotation angle is 180° or more and less than 360° (392° or more and less than 572° on the horizontal axis shown in Figure 6) Compression stroke of the first cylinder 241 + intake stroke of the second cylinder 242 (3rd stroke) When the crank rotation angle is 360° or more and less than 540° (572° or more and less than 32° on the horizontal axis shown in Figure 6) Combustion stroke of the first cylinder 241 + compression stroke of the second cylinder 242 (4th stroke) When the crank rotation angle is 540° or more and less than 720° (0°) (32° or more and less than 212° on the horizontal axis shown in Figure 6) Exhaust stroke of the first cylinder 241 + combustion stroke of the second cylinder 242

[0036] In such a cycle, pilot injection and main injection are performed from the injector between the compression stroke and the combustion stroke of each cylinder. In the example shown in FIG. 6, the first pilot injection P1 is started by the first injector 231 to the first cylinder 241 when the crank rotation angle shown on the horizontal axis is about 370°, and the first main injection M1 is started at about 490°. Next, the second pilot injection P2 is started by the second injector 232 to the second cylinder 242 when it is about 550°, and the second main injection M2 is started at about 670°. The second main injection M2 ends at about 720°. That is, in one cycle, the period from about 370° to about 720° in the crank rotation angle on the horizontal axis shown in FIG. 6 is the fuel injection period T1. On the other hand, in one cycle, the period other than the fuel injection period T1 is the fuel non-injection period T2 in which fuel injection is not performed from either the first injector 231 or the second injector 232.

[0037] In cam profile 620, during the period from when the cam lift amount shown on the vertical axis in Fig. 6 exceeds a predetermined value until it reaches its maximum value, plunger 611 is driven to pump fuel. The period from the crank rotation angle at which fuel pumping by cam 62 starts to the crank rotation angle at which fuel pumping ends is a fuel accumulation period T3 during which the fuel pressure inside fuel accumulator pipe 23 increases due to the pumping of fuel. When cam 62 has two cam lobes, first cam lobe 621 and second cam lobe 622, fuel is pumped twice during fuel accumulation period T3: by first cam lobe 621 (see region S1 shown in Fig. 6) and by second cam lobe 622 (see region S2 shown in Fig. 6).

[0038] The cam 62 of the fuel injection device 5 according to this embodiment has a cam profile 620 that completes sending the amount of fuel to be supplied to all cylinders (the first cylinder 241 and the second cylinder 242) to the fuel accumulator pipe 23 during the non-fuel injection period T2 in one cycle. That is, the cam 62 has a cam profile 620 that includes the fuel accumulation period T3 by the first cam lobe 621 and the second cam lobe 622 within the non-fuel injection period T2. This completes sending the amount of fuel to be supplied to all cylinders to the fuel accumulator pipe 23 during the period from after the latest main injection in one cycle (the second main injection M2 in the example shown in FIG. 6) to before the start of the earliest pre-injection.

[0039] By completing the accumulation of fuel in the amount to be supplied to all cylinders in one cycle during the non-fuel injection period T2, the accumulation of fuel required for each cylinder in one cycle in the fuel accumulator pipe 23 is completed before the fuel injection period T1 begins. That is, since the accumulation of fuel in the fuel accumulator pipe 23 is not performed during the fuel injection period T1, the variation in fuel pressure (such as pressure pulsation) during the fuel injection period T1 is suppressed. Therefore, all fuel injections including pilot injection and main injection are performed from the first injector 231 and the second injector 232 with the variation in fuel pressure suppressed, it is possible to perform stable fuel injection to each cylinder.

[0040] For example, when a pilot injection is performed at a very early stage in order to more effectively suppress the generation of soot, NOx, etc., the earlier the pilot injection, the longer the fuel injection period T1 within one cycle. By including the fuel accumulation period T3 in the non-fuel injection period T2 as in this embodiment, the pumping of fuel to be supplied to all cylinders is completed before the first pilot injection in one cycle. This eliminates the need for pumping of fuel during the fuel injection period T1, and since the fuel pressure in the fuel accumulator pipe 23 is stable during fuel injection, the fuel injection to each cylinder can be stabilized, and the variation in the fuel injection to each cylinder is suppressed.

[0041] In particular, when the engine 2 is a two-cylinder, four-stroke, one-cycle engine in which the strokes of the first cylinder 241 and the second cylinder 242 are shifted from each other by 180 degrees in crank rotation angle, approximately half of one cycle (crank rotation angle from 0° to 720°) is the fuel injection period T1, and approximately the remaining half is the non-fuel injection period T2. For this reason, a sufficient fuel accumulation period T3 can be included in the non-fuel injection period T2, making it easier to complete the pumping of fuel to all cylinders during the non-fuel injection period T2.

[0042] In the above example, the number of cam lobes in one revolution in cam profile 620 is two, but this is not limiting. That is, the number of cam lobes may be one as long as a sufficient amount of fuel is pumped in one drive of plunger 611. Also, the number of cam lobes may be three or more as long as the fuel pumping for all cylinders by the drive of plunger 611 can be completed in the non-fuel injection period T2 of one cycle.

[0043] As described above, according to this embodiment, it is possible to provide a fuel injection device 5 and an engine 2 that can stabilize the fuel pressure inside the fuel accumulator pipe 23 and suppress variation in fuel injection to each cylinder when fuel is injected from the first injector 231 to the first cylinder 241 and from the second injector 232 to the second cylinder 242.

[0044] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. The configurations of the above embodiments can be partially omitted or arbitrarily combined in a manner different from the above. [Explanation of symbols]

[0045] 2: engine, 3: exhaust gas recirculation device, 4: control unit, 5: fuel injection device, 21: intake pipe, 22: intake manifold, 23: fuel accumulator pipe, 24: cylinder block, 25: exhaust manifold, 26: exhaust pipe, 27: exhaust recirculation pipe, 28: flow rate adjustment means, 29: exhaust discharge pipe, 32: branching portion, 51: rotation sensor, 52: cam angle sensor, 53: NOx sensor, 54: temperature sensor, 55: pressure sensor, 56: water temperature sensor, 61: fuel pump, 62: cam, 71: crank gear, 72: idle gear, 73: cam gear, 211: air cleaner, 221: first branch pipe, 222: second branch pipe, 231: first injector, 232: second injector, 233: regulating valve, 234: emergency valve, 241: first cylinder, 242: second cylinder, 261: diesel oxidation catalyst, 611: plunger, 612: pressure delivery pipe, 613: return pipe, 620: cam profile, 621: first cam lobe, 622: second cam lobe, M1: first main injection, M2: second main injection, P1: first pilot injection, P2: second pilot injection, S1: region, S2: region, T1: fuel injection period, T2: fuel non-injection period, T3: fuel accumulation period, V1: apex, V2: apex, θ: rotation angle difference

Claims

1. A fuel injection device for use in a four-stroke, one-cycle, multi-cylinder engine, comprising: A plurality of injectors for injecting fuel into each cylinder; a fuel accumulator pipe that accumulates pressure in the fuel to be supplied to the plurality of injectors; a fuel pump that pumps the fuel to the fuel accumulator pipe; a cam that rotates based on the rotation of a crankshaft and has a cam profile for driving the fuel pump at a predetermined timing; a control unit that controls the injection of the fuel by each of the plurality of injectors; Equipped with the control unit controls timing of a main injection of the fuel by the injector and a pre-injection that is performed prior to the main injection, a cam having a cam profile that completes sending to the fuel accumulator an amount of the fuel to be supplied to all of the cylinders during a period from after the latest main injection to before the start of the earliest pre-injection among the fuel injections from the injector in one cycle.

2. 2. The fuel injection device according to claim 1, wherein the cam profile of the cam has a plurality of cam lobes for driving the fuel pump.

3. The cylinders include a first cylinder and a second cylinder, 2. The fuel injection device according to claim 1, wherein the strokes of the first cylinder and the second cylinder are shifted from each other by 180 degrees in crank rotation angle.

4. the cam profile of the cam has two cam lobes for driving the fuel pump; 4. The fuel injection device according to claim 3, wherein the positions of the apexes of the two cam lobes are asymmetric with respect to the rotation axis of the cam.

5. A four-stroke, one-cycle, multi-cylinder engine equipped with a fuel injection device that injects fuel into each cylinder, The fuel injection device includes: a plurality of injectors for injecting the fuel into each of the cylinders; a fuel accumulator pipe that accumulates pressure in the fuel to be supplied to the plurality of injectors; a fuel pump that pumps the fuel to the fuel accumulator pipe; a cam that rotates based on the rotation of a crankshaft and has a cam profile for driving the fuel pump at a predetermined timing; a control unit that controls the injection of the fuel by each of the plurality of injectors; Equipped with the control unit controls timing of a main injection of the fuel by the injector and a pre-injection that is performed prior to the main injection, an engine characterized in that the cam has a cam profile that completes sending to the fuel accumulator pipe an amount of the fuel to be supplied to all of the cylinders during a period from after the latest main injection to before the start of the earliest pre-injection among the fuel injections from the injector in one cycle.

6. The cylinders include a first cylinder and a second cylinder, 6. The engine according to claim 5, wherein the strokes of the first cylinder and the second cylinder are shifted from each other by 180 degrees in crank rotation angle.

Images