JP2017207010A - Fuel injection device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device of an engine, which irrespective of the operation state of the engine, can expedite atomization of fuel to improve combustion performance in each cylinder.SOLUTION: A fuel injection device of an engine comprises a fuel tank 24 with fuel stored therein, a feed pump 25 pressure-feeding the fuel of the fuel tank 24, first fuel injection valves 20 that are provided in intake passages 18 connected to intake ports 14 of the engine 10, respectively, and are supplied with the fuel from the fuel pump 25, and second fuel injection valves 21 that are provided on the upstream sides of the first fuel injection valves 20 in the intake passages 18, respectively, and have smaller maximum fuel injection amounts injectable per unit time than those of the first fuel injection valves 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection device for injecting fuel into an intake passage of an engine.

  Conventionally, as a fuel injection device (fuel injection system) for an engine (internal combustion engine), a cylinder injection valve (high pressure fuel injection valve) that directly injects high pressure fuel into each cylinder (combustion chamber), and a low pressure in the intake passage An intake passage injection valve (low pressure fuel injection valve) that injects fuel is known (see, for example, Patent Document 1).

  Thus, by setting it as the structure which injects a fuel from two fuel injection valves, atomization of a fuel can be accelerated | stimulated and the combustion performance of an engine can be improved. As described above, in the apparatus including the in-cylinder injection valve and the intake passage injection valve, the high-pressure fuel is directly injected into each cylinder from the in-cylinder injection valve, and the vaporization latent heat of the fuel is used for cooling the intake air. The occurrence of knocking can be suppressed by lowering the temperature of the air-fuel mixture. Furthermore, since the air density can be increased by cooling the intake air, the amount of intake air at the full load can be increased to improve the combustion performance. Further, by injecting low-pressure fuel from the intake passage injection valve into the intake passage, the residence time is secured and the homogenization of the air-fuel mixture can be promoted.

JP2013-83184A

  However, in an apparatus including an in-cylinder injection valve and an intake passage injection valve, for example, a part of the fuel injected from the in-cylinder injection valve burns before sufficiently vaporizing or collides with a combustion chamber wall, resulting in a liquid film There is a problem that particulate matter is exhausted because it burns in this state. In addition, since the tip of the in-cylinder injection valve is exposed to combustion gas, deposits may accumulate depending on the operating conditions due to carbonization of combustion products and fuel, which may cause variations in the fuel injection amount.

  The present invention has been made in view of such circumstances, and an engine fuel injection device that can promote fuel atomization and improve combustion performance in each cylinder regardless of the operating state of the engine. The purpose is to provide.

  A first aspect of the present invention that solves the above problems is an engine fuel injection device that injects fuel into an intake passage of an engine, a fuel tank that stores fuel, and a fuel that pumps fuel in the fuel tank A pump, a first fuel injection valve provided in the intake passage connected to the intake port of the engine and supplied with fuel from the fuel pump; and an upstream side of the first fuel injection valve in the intake passage And a second fuel injection valve that is provided on each side and has a maximum fuel injection amount that can be injected per unit time smaller than that of the first fuel injection valve.

  According to a second aspect of the present invention, in the engine fuel injection device according to the first aspect, the second fuel injection valve has an injection hole diameter smaller than that of the first fuel injection valve. In the fuel injector.

  According to a third aspect of the present invention, in the fuel injection device for an engine according to the first or second aspect, the second fuel injection valve is in contact with the fuel pump via the first fuel injection valve, A pressure reducing valve for reducing the pressure of the fuel supplied from the first fuel injection valve side to a predetermined pressure is provided between the first fuel injection valve and the second fuel injection valve. It is in the fuel injection device of the engine.

  According to a fourth aspect of the present invention, in the fuel injection device for an engine according to the third aspect, the fuel injection injected from the first fuel injection valve and the second fuel injection valve in accordance with the operating state of the engine. Fuel injection control means for controlling the amount is provided, and the fuel injection control means operates the pressure reducing valve in accordance with the operating state of the engine and adjusts the pressure of fuel supplied to the second fuel injection valve. The fuel injection device for an engine is characterized by the above.

  According to a fifth aspect of the present invention, in the fuel injection device for an engine according to the fourth aspect, the fuel injection control means is configured such that the operating state of the engine is equal to or lower than a predetermined first rotational speed and the predetermined first A fuel injection device for an engine characterized by adjusting the pressure of fuel supplied to the second fuel injection valve by operating the pressure reducing valve when in a low rotation and low load region that is less than is there.

  According to a sixth aspect of the present invention, in the fuel injection device for an engine according to the fourth or fifth aspect, the fuel injection control means injects from the second fuel injection valve at a time according to the operating state of the engine. The engine fuel injection apparatus is characterized in that the amount of pressure reduction by the pressure reducing valve is increased as the amount of fuel injection to be performed is smaller.

  According to the fuel injection device for an engine of the present invention, fuel is appropriately injected into the intake passage from the first fuel injection valve and the second fuel injection valve in accordance with the operating state of the engine. Atomization can be promoted, and the air-fuel mixture can be supplied into the cylinder (combustion chamber) in an optimal state. Therefore, irrespective of the operating state of the engine, the combustion performance in each cylinder can be improved and the fuel consumption and exhaust gas performance can be improved.

It is a figure showing the schematic structure of the engine containing the fuel injection device concerning one embodiment of the present invention. It is a figure showing the schematic structure of the engine containing the fuel injection device concerning one embodiment of the present invention. It is a figure which shows an example of the map which prescribes | regulates the driving | operation area | region of an engine. It is a figure which shows an example of the fuel injection timing in each driving | operation area | region.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  The engine 10 shown in FIGS. 1 and 2 is a multi-point injection multi-cylinder engine, for example, an in-line four-cylinder four-stroke engine. The engine body 11 has four cylinders 12 arranged in parallel. Has been. Each cylinder (combustion chamber) 12 is provided with an ignition plug 13 and an intake port 14 and an exhaust port 15. The intake port 14 is configured to be opened and closed by an intake valve 16. Similarly, the exhaust port 15 is configured to be opened and closed by an exhaust valve 17.

  Although not shown, the camshaft mounted on the engine body 11 is provided with a variable valve timing mechanism (VVT mechanism) that varies the opening / closing timing of the intake valve 16 and the exhaust valve 17. This variable valve timing mechanism changes the rotational phase of the cam with respect to the crankshaft (advance or retard), thereby causing the intake valve 16 to open the intake valve 16 and the exhaust valve 17 to close the exhaust valve 17. To change. Since a known variable valve timing mechanism may be applied, a detailed description thereof is omitted here. Further, this variable valve timing mechanism is not necessarily provided.

  The engine body 11 includes an intake manifold 18 connected to the intake port 14 and forming an intake passage, and an exhaust manifold 19 connected to the exhaust port 15.

  The intake manifold 18 is provided with a first fuel injection valve 20 and a second fuel injection valve 21 that inject fuel into the intake passage corresponding to each cylinder 12. More specifically, the intake manifold 18 includes a plurality of (four in the present embodiment) branch channel portions 18a connected to each intake port 14, and a communication channel in which the plurality of branch channel portions 18a communicate with each other. Part 18b. The first fuel injection valve 20 and the second fuel injection valve 21 are provided in each branch passage portion 18a of the intake manifold 18, respectively.

  In the case of a four-valve engine having two intake ports corresponding to each cylinder, the first fuel injection valve and the second fuel injection valve are provided so as to inject fuel into these two intake ports. Alternatively, a plurality of sets (two sets) may be provided corresponding to each of the intake ports.

  The first fuel injection valve 20 is disposed in the vicinity of the intake port 14 (in the vicinity of the combustion chamber 12) of the branch channel portion 18a. On the other hand, the second fuel injection valve 21 is disposed on the side of the communicating flow path portion 18b of the branch flow path portion 18a. That is, the second fuel injection valve 21 is disposed at a position farther from the combustion chamber 12 than the first fuel injection valve 20 (upstream of the intake passage).

  Each of the first fuel injection valves 20 is attached to the first delivery pipe 22. The first delivery pipe 22 is connected to a fuel tank 24 by a fuel pipe (fuel passage) 23. In the middle of the fuel pipe 23, for example, a fuel pump 25, which is an electric pump, is provided. The fuel in the fuel tank 24 is pumped up by the fuel pump 25 and supplied to the first delivery pipe 22 through the fuel pipe 23. The fuel supplied to the first delivery pipe 22 is distributed to each of the first fuel injection valves 20. In the present embodiment, the fuel pump 25 is provided outside the fuel tank 24, but the fuel pump 25 may be provided inside the fuel tank 24.

  In the present embodiment, the pressure of the fuel supplied to the first delivery pipe 22 by the fuel pump 25 is set to, for example, about 750 KPa. The fuel pressure may be constant regardless of the operating state of the engine 10 or may be changed according to the operating state of the engine 10.

  Further, a second delivery pipe 26 to which each of the second fuel injection valves 21 is attached is connected to the downstream side of the first delivery pipe 22 via a connection pipe 27. The connection pipe 27 is provided with a pressure reducing valve 28 including an electronic control valve that reduces the pressure of the fuel supplied from the first delivery pipe 22 to a predetermined pressure. The pressure reducing valve 28 adjusts the pressure of the fuel by controlling the passage pressure loss, and the pressure of the fuel decreases as the flow rate of the passing fuel decreases. The pressure reducing valve 28 may be an existing one, and the configuration is not particularly limited.

  As will be described in detail later, the fuel supplied from the first delivery pipe 22 to the connection pipe 27 is depressurized to a predetermined pressure by the pressure reducing valve 28 as necessary. Then, the decompressed fuel is supplied to the second delivery pipe 26, and is distributed from the second delivery pipe 26 to each of the second fuel injection valves 21.

  Here, the first fuel injection valve 20 and the second fuel injection valve 21 are both so-called solenoid injectors, but the second fuel injection valve 21 can inject per unit time (predetermined pulse width). The maximum fuel injection amount is smaller than that of the first fuel injection valve 20. Specifically, the nozzle hole diameter (injection hole diameter) of the second fuel injection valve 21 is smaller than the injection hole diameter of the first fuel injection valve 20. In other words, the maximum fuel injection amount that can be injected per unit time of the first fuel injection valve 20 is larger than that of the second fuel injection valve 20. Specifically, the diameter (injection hole diameter) of the nozzle hole of the first fuel injection valve 20 is larger than the injection hole diameter of the second fuel injection valve 21. By configuring the first fuel injection valve 20 and the second fuel injection valve 21 as described above, atomization of fuel can be promoted, and combustion performance is improved according to each operation state of the engine 10. Can do.

  In the present embodiment, the tip of the nozzle of the first fuel injection valve 20 is longer than the second fuel injection valve 21. Thereby, when fuel is injected from the first fuel injection valve 20, the length of the spray tends to be shortened, and the adhesion of fuel to the intake valve 16 is suppressed. In addition, when the number of injection holes of the first fuel injection valve 20 and the second fuel injection valve 21 is different, it is necessary to appropriately set the diameter of the nozzle hole of each fuel injection valve according to the number of injection holes.

  Further, one end of a return pipe (return passage) 30 is connected to the downstream side of the second delivery pipe 26 via a fuel pressure adjustment valve (regulator) 29. The other end side of the return pipe 30 is connected to the fuel tank 24. The fuel pressure adjusting valve 29 is for keeping the fuel pressure in the second delivery pipe 26 substantially constant, and mechanically opens when the fuel pressure in the second delivery pipe 26 becomes higher than a predetermined pressure. It is configured as follows.

As shown in FIG. 1, the intake pipe 31 connected to the intake manifold 18 is provided with a throttle valve 32, and a throttle position sensor (TPS) 33 that detects the valve opening degree of the throttle valve 32 is also provided. Is provided. Further, an air flow sensor 34 for detecting the intake air amount is provided upstream of the throttle valve 32. A three-way catalyst 36 that is an exhaust purification catalyst is interposed in the exhaust pipe 35 connected to the exhaust manifold 19. An O ₂ sensor 37 for detecting the O ₂ concentration of the exhaust gas after passing through the catalyst is provided on the outlet side of the three-way catalyst 36, and the air-fuel ratio of the exhaust gas before passing through the catalyst is provided on the inlet side of the three-way catalyst 36. A linear air-fuel ratio sensor 38 for detecting (exhaust air-fuel ratio) is provided.

The engine 10 having such a configuration is controlled by an electronic control unit (ECU) 40. The ECU 40 includes an input / output device, a storage device that stores a control program, a control map, and the like, a central processing unit, a timer, and counters. The ECU 40 performs comprehensive control of the engine 10 based on information from various sensors. For example, in addition to the throttle position sensor (TPS) 33, the air flow sensor 34, the O ₂ sensor 37, and the linear air-fuel ratio sensor 38, various sensors such as a crank angle sensor and an accelerator position sensor are connected to the ECU 40. Various controls are executed based on detection information from these sensors.

  The ECU 40 also functions as a fuel injection device according to the present invention, and appropriately determines the fuel injection amount injected from the first fuel injection valve 20 and the second fuel injection valve 21 based on information from various sensors. Control. Specifically, the ECU 40 includes a fuel control unit 50 as a fuel injection control device of the engine 10. The fuel control unit 50 includes an operation state detection unit 51 and a fuel injection control unit 52.

  The driving state detection means 51 detects the driving state of the engine 10 based on information from the various sensors described above, for example, the load of the engine 10, changes in the rotation speed (rotational speed), and the like. In the present embodiment, the operation state detection unit 51 refers to, for example, a predetermined operation region map or the like, and determines which operation region the operation state of the engine 10 is in.

  As shown in FIG. 3, the operation region map is preset based on the rotational speed and load of the engine 10 and stored by the ECU 40. In this example, first to fourth operation regions D1 to D4 are set as the operation state of the engine 10. The operation state detection means 51 determines which of the first to fourth operation regions D1 to D4 the operation state of the engine 10 corresponds to.

  The fuel injection control means 52 selects the fuel injection mode according to the operating state of the engine 10, that is, based on the detection result of the operating state detection means 51, and the first fuel injection valve 20 and the second fuel injection valve 21. The amount of fuel injected from is appropriately controlled. In the present embodiment, the fuel injection control means 52 is a mode in which fuel is injected only from the second fuel injection valve 21 (hereinafter referred to as “first injection” when the operating state of the engine 10 is the first operating region D1. Mode)). When the operation state of the engine 10 is the second operation region D2 or the fourth operation region D4, a mode in which fuel is injected from the first fuel injection valve 20 and the second fuel injection valve 21 (hereinafter referred to as “second operation region”). 2) is called and executed. When the operating state of the engine 10 is the third operating region D3, a mode in which fuel is injected only from the first fuel injection valve 20 (hereinafter referred to as “third injection mode”) is selected and executed.

  The fuel injection control means 52 selects and executes the second injection mode when the operation state of the engine 10 is the second operation region D2 or the fourth operation region D4, and the first fuel injection valve 20 and the first operation region D4. The fuel is injected from the second fuel injection valve 21. The timing (injection start timing) at which the fuel is injected from the first fuel injection valve 20 and the second fuel injection valve 21 (injection start timing) is the second operating region D2 and the fourth. The operation region D4 is appropriately changed.

  FIG. 4 is a diagram illustrating an example of timing for injecting fuel from the first fuel injection valve 20 and the second fuel injection valve 21 in each operation region. As described above, when the operation state of the engine 10 is the first operation region D1, the first injection mode is selected and executed. The timing of fuel injection by the second fuel injection valve 21 in the first operation region D1 is set to the first stage injection in the exhaust stroke taking into account the transport delay, as shown in FIG. 4 (a).

  Here, in the first operation region D1, the valve overlap is relatively large by the VVT mechanism, and the so-called internal EGR is increased. For this reason, there is a jet back from the exhaust side to the intake side, and accordingly, the amount of intake air flowing into the cylinder (combustion chamber) 12 may decrease. For this reason, when fuel is injected from the first fuel injection valve 20, the spray cannot get on the intake air, and the fuel may not be appropriately conveyed to the cylinder (combustion chamber) 12. However, by injecting fuel from the second fuel injection valve 21 at the above timing, the spray can be appropriately carried into the cylinder (combustion chamber) 12 by intake air.

  In the second operation region D2 and the fourth operation region D4, the second injection mode is selected and executed. As shown in FIG. 4B, the timing of fuel injection by the second fuel injection valve 21 in the second operation region D2 is similar to that in the first operation region D1, taking into account the transport delay, and the exhaust stroke. The first stage injection is set. On the other hand, the timing of fuel injection by the first fuel injection valve 20 is set to two-stage injection in the intake stroke. In this example, the first stage injection (main injection) is set to a state where the lift of the intake valve 16 is high, that is, the timing at which the intake port 14 is largely opened, and the second stage injection is the timing at which the intake valve 16 is closed. That is, it is set immediately before the end of the intake stroke.

  The second operation region D2 is a region where the throttle opening is relatively large but the flow rate of the intake air is not so high. Therefore, by injecting fuel from the second fuel injection valve 21 at the above timing, the fuel is supplied to the cylinder (combustion chamber) 12 in a sufficiently vaporized state. Furthermore, fuel shortage can also be suppressed by injecting fuel from the first fuel injection valve 20. The second operation region D2 does not require a flow rate, for example, as compared with the fourth operation region D4. Therefore, the second penetration region D2 reduces the spray penetration force (spray length) to the intake port 14 by using two-stage injection. It is possible to reduce the amount of fuel attached. Note that the fuel injection by the first fuel injection valve 20 does not necessarily have to be two-stage injection, and of course may be single-stage injection.

  The timing of fuel injection by the second fuel injection valve 21 in the fourth operation region D4 is set to one-stage injection in the exhaust stroke, as shown in FIG. The fuel injection timing is set to one-stage injection in the intake stroke. Since the fourth operation region D4 includes a region where the load is maximum, a maximum flow rate is required. For this reason, instead of the two-stage injection having an intermediate interval, the first-stage injection is performed, and the fuel is continuously blown as much as possible when the intake valve 16 is opened.

  When the operation state of the engine 10 is the third operation region D3, the third injection mode is selected and executed. The timing of fuel injection by the first fuel injection valve 20 in the third operation region D3 is set to one-stage injection in the intake stroke, as shown in FIG. 4 (d).

  In the third operation region D3, the valve overlap is relatively large by the VVT mechanism so that the intake air is sufficiently supplied into the cylinder (combustion chamber) 12. For this reason, the fuel is injected from the first fuel injection valve 20 in the intake stroke. Specifically, since the pressure of the fuel injected from the first fuel injection valve 20 is relatively high (higher than the conventional engine), the injection amount per unit time is relatively large (more than the conventional engine). . For this reason, the injection period is made relatively short, and injection is performed at a timing when the lift of the intake valve 16 is high. Thereby, the adhesion of the fuel to the intake valve 16 can be reduced, the direct injection rate of the fuel into the cylinder (combustion chamber) 12 can be increased, and the occurrence of knocking can be suppressed accordingly.

  As described above, the injection mode is appropriately selected and executed according to which operating region the operating state of the engine 10 is, and the timing of fuel injection by the first fuel injection valve 20 and the second fuel injection valve 21 is appropriately set. By doing so, the atomization of fuel can be promoted, and the air-fuel mixture can be supplied to the cylinder (combustion chamber) 12 in an optimum state. Therefore, regardless of the operating state of the engine 10, the combustion performance in each cylinder 12 can be improved and the fuel consumption and exhaust gas performance can be improved.

  Further, in the present embodiment, the fuel injection control means 52 controls the opening of the pressure reducing valve 28 via the second delivery pipe 26 when the operating state of the engine 10 is in the low load and low rotation range. The pressure of the fuel supplied to each second fuel injection valve 21 is reduced to a predetermined first pressure.

  Here, the low rotation / low load operation region is an operation region where the rotation speed of the engine 10 is equal to or less than a predetermined first rotation speed n1 and equal to or less than the first load P1. For example, in the map of FIG. 3, the first operation region D1 and the second operation region D2 correspond to the low rotation and low load operation region. Note that the third operating region D3 and the fourth operating region D4 are high in which the rotational speed of the engine 10 is higher than the predetermined first rotational speed n1 and higher than the first load P1. Corresponds to the rotational high load operation region. In other words, the low rotation / low load region is divided into two operation regions (first operation region D1 and second operation region D2), and the high rotation / high load region is divided into two operation regions (third operation region D3). And the fourth operation region D4).

  That is, in this embodiment, the fuel injection control means 52 controls the opening degree of the pressure reducing valve 28 when the operating state of the engine 10 is the first operating region D1 or the second operating region D2. The pressure of the fuel supplied to each second fuel injection valve 21 via the two delivery pipes 26 is reduced to a predetermined first pressure (for example, about 300 KPa).

  In the present embodiment, the fuel pressure is reduced to the first pressure in both the first operation region D1 and the second operation region D2, but the first operation region D1 and the first operation region D1 The amount of reduced pressure may be changed in the second operation region D2. Specifically, the decompression amount may be increased in the operation region where the amount of fuel injected from the second fuel injection valve 21 is small.

  As described above, when the operating state of the engine 10 is in the low rotation and low load region (the first operating region D1 or the second operating region D2), the pressure of the fuel supplied to the second fuel injection valve 21 is reduced. By doing so, the amount of fuel adhering to the manifold can be suppressed, and the fuel can be appropriately mixed with the intake air to further improve the combustion performance in each cylinder 12.

  Specifically, when the operating state of the engine 10 is a low-rotation low-load operating region (first operating region D1 or second operating region D2), the air flow rate is relatively small. For this reason, even when the fuel is injected from the second fuel injection valve 21 arranged at a position far from the combustion chamber 12, there is a possibility that the mixing of the fuel and the intake air becomes insufficient. As a result, the combustion performance (combustion efficiency) is deteriorated, and there is a possibility that the fuel consumption is reduced or the exhaust gas is adversely affected. However, when the operating state of the engine 10 is in the low rotation and low load operation region (the first operation region D1 or the second operation region D2), the pressure of the fuel supplied to the second fuel injection valve 21 is By reducing the pressure, it is possible to inject a small amount of fuel suitable for the operating state of the engine 10, reduce the spray penetration force, and reduce the amount of fuel adhering to the manifold. Therefore, fuel and intake air can be mixed more appropriately.

  On the other hand, since the pressure of the fuel injected from the first fuel injection valve 20 in the second operation region D2 is set higher than that of the conventional engine, the injection amount per unit time is relatively large. For this reason, a desired amount of fuel can be injected while the injection period is relatively short and the lift of the intake valve 16 is high. Thereby, the adhesion of the fuel to the intake valve 16 can be reduced, and the direct injection rate of the fuel into the cylinder (combustion chamber) 12 can be increased.

  In the present embodiment, when the operating state of the engine 10 is the third operating state D3 and the fourth operating region D4, the fuel is not depressurized by the pressure reducing valve 28, but is appropriately executed as necessary. You may do it.

  Even when the operating state of the engine 10 is in the same operating region, the fuel injection amount injected at a time from the second fuel injection valve 21 may be appropriately changed. Thus, when the fuel injection amount is changed according to the operating state of the engine 10, the fuel injection control means 52 may adjust the pressure reduction amount by the pressure reducing valve 28 according to the change of the fuel injection amount. Good. Specifically, the pressure reduction amount by the pressure reducing valve 28 may be increased as the fuel injection amount injected from the second fuel injection valve 21 at a time is smaller. Thereby, a fuel can be mixed with intake air more appropriately and the combustion performance in each cylinder 12 can be improved.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

  For example, in the above-described embodiment, the present invention has been described by exemplifying a four-cylinder engine. However, the fuel injection device of the present invention can be applied to, for example, a three-cylinder or six-cylinder engine. .

10 engine 11 engine body 12 cylinder (combustion chamber)
13 Spark Plug 14 Intake Port 15 Exhaust Port 16 Intake Valve 17 Exhaust Valve 18 Intake Manifold 18a Branch Flow Section (Intake Passage)
18 b Communication channel 19 Exhaust manifold 20 First fuel injection valve 21 Second fuel injection valve 22 First delivery pipe 23 Fuel pipe 24 Fuel tank 25 Feed pump 26 Second delivery pipe 27 Connection pipe 28 Pressure reducing valve 29 Fuel pressure regulating valve 30 Return pipe 31 Intake pipe 32 Throttle valve 33 Throttle position sensor (TPS)
34 Airflow sensor 35 Exhaust pipe 36 Three-way catalyst 37 O ₂ sensor 38 Linear air-fuel ratio sensor 50 Fuel controller 51 Operating state detection means 52 Fuel injection control means

Claims (6)

An engine fuel injection device for injecting fuel into an intake passage of an engine,
A fuel tank in which fuel is stored;
A fuel pump for pumping fuel in the fuel tank;
A first fuel injection valve provided in the intake passage connected to the intake port of the engine and supplied with fuel from the fuel pump;
A second fuel injection valve provided upstream of the first fuel injection valve in the intake passage and having a maximum fuel injection amount that can be injected per unit time less than that of the first fuel injection valve; A fuel injection device for an engine, comprising: The fuel injection device for an engine according to claim 1,
The engine fuel injection device according to claim 1, wherein the second fuel injection valve has an injection hole diameter smaller than that of the first fuel injection valve. The engine fuel injection device according to claim 1 or 2,
The second fuel injection valve is connected to the fuel pump via the first fuel injection valve;
A pressure reducing valve for reducing the pressure of the fuel supplied from the first fuel injection valve side to a predetermined pressure is provided between the first fuel injection valve and the second fuel injection valve. An engine fuel injection device. The engine fuel injection device according to claim 3,
Fuel injection control means for controlling the amount of fuel injected from the first fuel injection valve and the second fuel injection valve in accordance with the operating state of the engine;
The fuel injection control device according to claim 1, wherein the fuel injection control means operates the pressure reducing valve in accordance with an operating state of the engine to adjust a pressure of fuel supplied to the second fuel injection valve. The fuel injection device for an engine according to claim 4,
The fuel injection control means operates the pressure reducing valve when the operating state of the engine is in a low rotation and low load region that is equal to or lower than a predetermined first rotational speed and equal to or lower than a predetermined first load. A fuel injection device for an engine, wherein the pressure of the fuel supplied to the second fuel injection valve is adjusted. The fuel injection device for an engine according to claim 4 or 5,
The fuel injection control means increases an amount of pressure reduction by the pressure reducing valve as a fuel injection amount injected from the second fuel injection valve at a time is small according to an operating state of the engine. Fuel injection device.