Fuel injection device, and control method

Abstract

This fuel injection device, which injects a fuel into a combustion chamber of an internal combustion engine, comprises: an injection port for injecting the fuel into the combustion chamber; a first flow passage which connects the injection port and a high-pressure source that supplies the fuel at a predetermined pressure, and to which the fuel is supplied from the high-pressure source; a first valve which is provided to the first flow passage and performs opening / closing of the injection port; a second flow passage which is connected to the first flow passage and to which the fuel is supplied from the first flow passage; and a second valve which is provided to the second flow passage and performs opening / closing of the second flow passage.

Description

Technical Field

[0001] This invention relates to a fuel injection device , and and a control method. This application claims priority based on Japanese Patent Application No. 2021-199326 filed in Japan on December 8, 2021, and incorporates its content herein by reference.

Background Art

[0002] In a fuel injection type internal combustion engine such as a diesel engine, research and development of technologies for improving the combustion efficiency of fuel are being carried out.

[0003] Regarding this, a method of driving a valve that opens and closes an injection port for injecting fuel into the combustion chamber of a fuel injection type internal combustion engine with a piezo element is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The method as described in Patent Document 1 can improve the responsiveness to the control for opening and closing the injection port, and can make the rise of the fuel injection rate steep. The steeper the rise of the fuel injection rate, the higher the combustion efficiency of the fuel.

[0006] Here, the rise in the fuel injection rate can be made steeper by increasing the fuel injection pressure. This means that even when using the method described in Patent Document 1, there is still room to further improve the combustion efficiency of the fuel in a fuel injection type internal combustion engine. And as a method of increasing the fuel injection pressure, a method of increasing the pressure of the high-pressure source that supplies fuel into the combustion chamber is known. However, in order to increase the pressure of the high-pressure source, it is necessary to improve the pressure resistance of the entire system that supplies fuel into the combustion chamber. This is not preferable because it leads to an increase in the weight of the internal combustion engine, an increase in the manufacturing cost of the internal combustion engine, etc.

[0007] Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and a fuel injection device , and and a control method capable of injecting fuel by a pressure higher than the pressure of the high-pressure source are provided.

Means for Solving the Problems

[0008] In order to solve the above-described problems, a fuel injection device according to an aspect of the present invention is a fuel injection device that injects fuel into a combustion chamber of an internal combustion engine, and includes an injection port that injects the fuel into the combustion chamber, a high-pressure source that supplies the fuel at a predetermined pressure, and a first flow path that connects the high-pressure source and the injection port and through which the fuel is supplied from the high-pressure source, a first valve provided in the first flow path that opens and closes the injection port, a first pipe line connected to the first flow path and through which the fuel is supplied from the first flow path, a first drive unit provided in the first pipe line that drives the first valve by the pressure of the fuel supplied through the first pipe line and causes the first valve to open and close the injection port, a second flow path connected to the first flow path and through which the fuel is supplied from the first flow path, and a second valve provided in the second flow path that opens and closes the second flow path. , the first drive unit causes the first valve to open and close the injection port by electronic control independent of the electronic control of the opening and closing of the second valve. 。

[0011] Also, in order to solve the above-described problems, a control method according to an aspect of the present invention is a control method for a fuel injection device that injects fuel into a combustion chamber of an internal combustion engine. The fuel injection device includes an injection port that injects the fuel into the combustion chamber, a high-pressure source that supplies the fuel at a predetermined pressure, and a first flow path that connects the high-pressure source and the injection port and through which the fuel is supplied from the high-pressure source, a first valve provided in the first flow path that opens and closes the injection port, a first pipeline connected to the first flow path and supplied with the fuel from the first flow path, and provided in the first pipeline, and driving the first valve by the pressure of the fuel supplied through the first pipeline, a first drive unit that causes the first valve to open and close the injection port, a second flow path that is connected to the first flow path and through which the fuel is supplied from the first flow path, a second valve provided in the second flow path that opens and closes the second flow path, and a second drive unit that causes the second valve to open and close the second flow path. The control method includes a first step of opening the second flow path by the second valve while the first valve closes the injection port, a second step of closing the second flow path by the second valve after a predetermined time has elapsed since the second valve opened the second flow path in the first step, and a third step of opening the injection port by the first valve at a timing after the timing when the second valve closed the second flow path in the second step.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a fuel injection device , and and a control method capable of injecting fuel at a pressure higher than the pressure of the high-pressure source.

Brief Description of the Drawings

[0014] [Figure 1] It is a diagram showing an example of the configuration of the fuel injection device 1. [Figure 2] It is a diagram showing an example of the hardware configuration of the ECU 3. [Figure 3] It is a diagram showing an example of the functional configuration of the ECU 3. [Figure 4] FIG. showing an example of each of the opening and closing timings of the injection port H and the second flow path F2 in the fuel injection device 1, the temporal change in the pressure in the first flow path F1, the temporal change in the lift amount of the first valve V1, the temporal change in the fuel injection pressure, and the temporal change in the fuel injection rate. [Figure 5] FIG. showing an example of each of the opening and closing timings of the injection port H and the second flow path F2 in the fuel injection device 1A, the temporal change in the pressure in the first flow path F1, the temporal change in the lift amount of the first valve V1, the temporal change in the fuel injection pressure, and the temporal change in the fuel injection rate. [Figure 6] FIG. showing another example of the configuration of the fuel injection device 1B. [Figure 7] FIG. showing another example of the functional configuration of the ECU 3. [Figure 8] FIG. showing an example of each of the opening and closing timings of the injection port H, the first flow path F1, and the second flow path F2 in the fuel injection device 1B, the temporal change in the pressure in the first flow path F1, the temporal change in the pressure in the space S, the temporal change in the lift amount of the first valve V1, the temporal change in the fuel injection pressure, and the temporal change in the fuel injection rate. [Figure 9] FIG. showing an example of each of the opening and closing timings of the injection port H, the first flow path F1, and the second flow path F2 in the fuel injection device 1C, the temporal change in the pressure in the first flow path F1, the temporal change in the pressure in the space S, the temporal change in the lift amount of the first valve V1, the temporal change in the fuel injection pressure, and the temporal change in the fuel injection rate. [Figure 10] FIG. showing an example of the configuration of the fuel injection system 10. [Figure 11] FIG. showing an example of each of the opening and closing timings of the second flow path F2, the opening and closing timings of the injection ports H of the four fuel injection devices 1D, and the temporal change in the pressure in the four first flow paths F1.

MODE FOR CARRYING OUT THE INVENTION

[0015] <EMBODIMENT> Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the time from the timing when the increase of a certain physical quantity starts to the timing when the physical quantity reaches its maximum value is shortened, which is described as the steepening of the rise of the physical quantity. Also, in this embodiment, the increase in the maximum value of the physical quantity is described as the sharpening of the rise of the physical quantity. The physical quantity is, for example, the injection pressure of fuel, the injection rate of fuel, etc. that appear below, but is not limited thereto.

[0016] <Overview of the fuel injection device> First, the overview of the fuel injection device 1 according to the embodiment will be described.

[0017] The fuel injection device 1 is a device that is provided in a fuel injection type internal combustion engine EG and injects (supplies) fuel into the combustion chamber CC of the internal combustion engine EG. The internal combustion engine EG is an internal combustion engine equipped with a common rail injection system. The internal combustion engine EG is, for example, a diesel engine provided in an automobile, a ship, a railway vehicle, a heavy machine, etc. Therefore, the fuel is, in this example, light oil. Note that the internal combustion engine EG may be another fuel injection type internal combustion engine such as a fuel injection type gasoline engine instead of the diesel engine.

[0018] Here, as a method for increasing the combustion efficiency of fuel in the internal combustion engine EG, a method of increasing the injection pressure of fuel into the combustion chamber CC is known. This can be realized, for example, by increasing the pressure of the high-pressure source that supplies fuel into the combustion chamber CC. However, in order to increase the pressure of the high-pressure source, it is necessary to improve the pressure resistance of the entire system that supplies fuel into the combustion chamber CC. This is not preferable because it causes an increase in the weight of the internal combustion engine EG, an increase in the manufacturing cost of the internal combustion engine EG, etc.

[0019] Therefore, the fuel injection device 1 includes an injection port, a first flow path, a first valve, a second flow path, and a second valve. The injection port is an opening for injecting fuel into the combustion chamber CC. The first flow path connects a high-pressure source (common rail) that supplies fuel at a predetermined pressure and the injection port, and fuel is supplied from the high-pressure source. The predetermined pressure is the reference pressure in the fuel injection device 1. The first valve is provided in the first flow path and opens and closes the injection port. The second flow path is connected to the first flow path, and fuel is supplied from the first flow path. The second valve is provided in the second flow path and opens and closes the second flow path. Thereby, the fuel injection device 1 can block the flow of fuel into the second flow path by closing the second flow path with the second valve while the injection port is closed by the first valve. In this case, due to the water hammer action of the blocked fuel, the pressure in the first flow path instantaneously becomes higher than the predetermined pressure. As a result, the fuel injection device 1 can inject fuel into the combustion chamber CC at a pressure higher than the predetermined pressure by opening the injection port during the period when the pressure in the first flow path is higher than the predetermined pressure. The higher the initial injection pressure of the fuel, the steeper and sharper the rise of the injection rate of the fuel injected into the combustion chamber CC. That is, the fuel injection device 1 can further improve the combustion efficiency of the fuel. Here, in the internal combustion engine EG, when the combustion efficiency of the fuel is improved, the fuel consumption rate per unit time decreases according to the combustion state in the combustion chamber CC. For this reason, the fuel injection device 1 can also improve the convenience for the user. Hereinafter, the configuration of the fuel injection device 1 and the control method of the fuel injection device 1 will be described in detail.

[0020] <Configuration of Fuel Injection Device> Hereinafter, the configuration of the fuel injection device 1 according to the embodiment will be described.

[0021] FIG. 1 is a diagram showing an example of the configuration of the fuel injection device 1. The fuel injection device 1 includes a fuel injector 2 and an ECU (Electronic Control Unit) 3 that controls the fuel injector 2. Note that the fuel injection device 1 may be configured without the ECU 3.

[0022] Fuel injector 2 is supplied with fuel from high-pressure source 4 at a predetermined pressure Pb. Here, high-pressure source 4 is a common rail provided in internal combustion engine EG. Fuel injector 2 injects the fuel supplied from high-pressure source 4 into combustion chamber CC according to the control by ECU 3. Note that a common rail pressure regulating valve (pressure relief valve) is provided in high-pressure source 4. However, in FIG. 1, for simplicity of the drawing, the illustration of the common rail pressure regulating valve is omitted.

[0023] Fuel injector 2 is, for example, an electric injector. Fuel injector 2 includes a first flow path F1, an injection port H, a first valve V1, a drive unit A1, a second flow path F2, a second valve V2, and a drive unit A2.

[0024] First flow path F1 is a pipe line formed inside the housing of fuel injector 2. Also, first flow path F1 is a pipe line through which fuel supplied from high-pressure source 4 at a predetermined pressure Pb passes. Also, first flow path F1 is a pipe line connecting high-pressure source 4 and injection port H. That is, the fuel supplied from high-pressure source 4 at a predetermined pressure Pb reaches injection port H through first flow path F1.

[0025] Injection port H is an opening formed in first flow path F1. For this reason, the fuel supplied from high-pressure source 4 to first flow path F1 is injected (supplied) from injection port H into combustion chamber CC. That is, injection port H injects fuel into combustion chamber CC.

[0026] First valve V1 is provided in first flow path F1 and opens and closes injection port H. In the present embodiment, the state where injection port H is open means a state in which the fuel supplied from first flow path F1 can be injected from injection port H into combustion chamber CC. Also, in the present embodiment, the state where injection port H is closed means a state in which the fuel supplied from first flow path F1 cannot be injected from injection port H into combustion chamber CC. For this reason, the opening and closing of injection port H may be realized by the opening and closing of injection port H itself, or may be realized by the opening and closing of first flow path F1. Hereinafter, as an example, the case where the opening and closing of injection port H is realized by the opening and closing of injection port H itself will be described.

[0027] In the example shown in FIG. 1, the first valve V1 is a nozzle needle. Note that the first valve V1 may be any member as long as it is a member that can open and close the injection port H instead of the nozzle needle.

[0028] The first valve V1 closes the injection port H by closing the injection port H with the tip of the first valve V1. More specifically, the first valve V1 does not move while closing the injection port H when the ECU 3 is not driving the drive unit A1. As a result, the first valve V1 continues to close the injection port H in this case. On the other hand, the first valve V1 moves in a direction away from the injection port H when the ECU 3 drives the drive unit A1. As a result, the first valve V1 moves away from the injection port H in that direction, and the injection port H opens in this case.

[0029] The drive unit A1 causes the first valve V1 to open and close the injection port H. The drive unit A1 has, for example, a solenoid, a piezo element, etc. as an actuator for driving the first valve V1. When the drive unit A1 is not driven by the ECU 3, the pressure of the fuel supplied through the pipeline connected to the first flow path F1 (i.e., a predetermined pressure Pb) presses the tip of the first valve V1 against the injection port H and keeps the injection port H closed. That is, in this case, the drive unit A1 continuously closes the injection port H with the first valve V1. Here, this pipeline connects the first flow path F1 and a discharge port through which the fuel passing through this pipeline is discharged. This discharge port is connected, for example, to a fuel tank (this fuel tank may or may not be connected to the high-pressure source 4) via a pipeline not shown. Therefore, the fuel flowing out from this discharge port finally returns to the fuel tank. Note that the configuration from this discharge port onward may be any configuration instead. Therefore, further detailed description of the configuration from this discharge port onward is omitted. On the other hand, when the drive unit A1 is driven by the ECU 3, the pressure of the fuel supplied through this pipeline (i.e., a predetermined pressure Pb) is reduced by opening a valve provided in the drive unit A1, and the first valve V1 is moved in a direction away from the injection port H. That is, in this case, the drive unit A1 opens the injection port H with the first valve V1. Note that the structure and operation regarding the opening and closing of the first valve V1 may be known structures and operations, or structures and operations to be developed in the future, so further detailed description is omitted.

[0030] The second flow path F2 is a pipe line formed inside the housing of the fuel injector 2. Further, the second flow path F2 is a pipe line connecting the first flow path F1 and a discharge port through which the fuel passing through the second flow path F2 is discharged. In other words, the second flow path F2 is a pipe line connected to the first flow path F1. Therefore, fuel is supplied to the second flow path F2 from the first flow path F1. Here, this discharge port is connected to, for example, a fuel tank (this fuel tank may or may not be connected to the high-pressure source 4) via a pipe line not shown. Therefore, the fuel flowing out from this discharge port through the second flow path F2 finally returns to the fuel tank. Note that the configuration after this discharge port may be any configuration instead. Therefore, further detailed description of the configuration after this discharge port is omitted.

[0031] The second valve V2 is provided in the second flow path F2 and opens and closes the second flow path F2. In the present embodiment, the state where the second flow path F2 is open means a state in which the fuel supplied from the first flow path F1 flows through the second flow path F2 to the discharge port through which the fuel passing through the second flow path F2 is discharged. Further, in the present embodiment, the state where the second flow path F2 is closed means a state in which the fuel supplied from the first flow path F1 does not flow through the second flow path F2 to the discharge port through which the fuel passing through the second flow path F2 is discharged. Therefore, the opening and closing of the second flow path F2 may be realized by opening and closing the second flow path F2 itself, or may be realized by opening and closing the connection portion between the first flow path F1 and the second flow path F2. Hereinafter, as an example, the case where the opening and closing of the second flow path F2 is realized by opening and closing the second flow path F2 itself will be described. Here, the second valve V2 can also be described as a valve that changes the pressure in the first flow path F1 by opening and closing the second flow path F2. However, the second valve V2 is a valve additionally provided in the second flow path F2 separately from the common rail pressure regulating valve, and is not a valve that functions as a common rail pressure regulating valve. The common rail pressure regulating valve is a valve that discharges fuel from the high-pressure source 4, which is the pressure generation source, so that the pressure of the high-pressure source 4 does not malfunction when the pressure of the high-pressure source 4 rises too much. Therefore, the common rail pressure regulating valve is usually provided in the high-pressure source 4 itself. On the other hand, the position of the connection portion between the first flow path F1 and the second flow path F2 is preferably closer to the injection port H. And the position of the second valve V2 is also preferably closer to the injection port H. This is because it is desired to increase the pressure of the fuel injected from the injection port H into the combustion chamber CC by the above-described water hammer action. Further, using the second valve V2 instead of the common rail pressure regulating valve means changing the pressure in the first flow path F1 irregularly, leading to making the pressure in the first flow path F1 unstable, which is not appropriate. For the above reasons, the fuel injection device 1 is provided with the second valve V2 as an additional valve separate from the common rail pressure regulating valve.

[0032] The second valve V2 may be any member as long as it is a member that can open and close the second flow path F2 in response to the drive of the drive unit A2. For this reason, in FIG. 1, for convenience, the second valve V2 is shown as a rectangle.

[0033] The second valve V2 closes the second flow path F2 by blocking the second flow path F2. More specifically, when the ECU 3 is not driving the drive unit A2, the second valve V2 blocks the second flow path F2, and as a result, closes the second flow path F2. On the other hand, when the ECU 3 drives the drive unit A2, the second valve V2 moves in the direction to open the second flow path F2 and opens the second flow path F2.

[0034] The drive unit A2 causes the second valve V2 to open and close the second flow path F2. The drive unit A2 has, for example, a solenoid, a piezo element, etc. as an actuator that drives the second valve V2. When the drive unit A2 is not driven by the ECU 3, it does not move the second valve V2 and continues to close the second flow path F2. On the other hand, when the drive unit A2 is driven by the ECU 3, it moves the second valve V2 in the direction to open the second flow path F2 and opens the second flow path F2. Note that the structure and operation regarding the opening and closing of the second valve V2 may be known structures and operations, or may be structures and operations to be developed in the future, so further detailed description is omitted.

[0035] <Functional Configuration of ECU> Hereinafter, with reference to FIG. 2, the functional configuration of the ECU 3 will be described. FIG. 2 is a diagram showing an example of the hardware configuration of the ECU 3. The ECU 3 includes, for example, a CPU (Central Processing Unit) 31, a storage unit 32, a first valve drive circuit 33, and a second valve drive circuit 34. These components are connected to be communicable with each other via a bus. Also, the ECU 3 may be configured to include a communication unit for communicating with other ECUs.

[0036] The CPU 31 executes various programs stored in the storage unit 32. Note that the CPU 31 may be another processor such as an FPGA (Field Programmable Gate Array). The memory unit 32 includes, for example, an EEPROM (Electrically Erasable Programmable Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The memory unit 32 stores various types of information processed by the ECU 3.

[0037] The first valve drive circuit 33 supplies a drive current that drives a drive unit A1 which opens and closes the first valve V1 to the drive unit A1. The second valve drive circuit 34 supplies a drive current that drives a drive unit A2 which opens and closes the second valve V2 to the drive unit A2.

[0038] <Functional Configuration of ECU> Hereinafter, with reference to FIG. 3, the functional configuration of the ECU 3 will be described. FIG. 3 is a diagram showing an example of the functional configuration of the ECU 3. The ECU 3 includes a memory unit 32, a first valve drive circuit 33, a second valve drive circuit 34, and a control unit 36.

[0039] The control unit 36 controls the first valve drive circuit 33 and causes the drive unit A1 to open and close the injection port H by the first valve V1 according to the timing pre-stored in the memory unit 32. Further, the control unit 36 controls the second valve drive circuit 34 and causes the drive unit A2 to open and close the second flow path F2 by the second valve V2 according to the timing pre-stored in the memory unit 32. The control unit 36 is realized, for example, by the CPU 31 executing a program stored in the memory unit 32. Also, the control unit 36 may be a hardware functional unit such as an LSI (Large Scale Integration) or an ASIC (Application Specific Integrated Circuit).

[0040] <Control Method of Fuel Injection Device> Hereinafter, with reference to FIG. 4, a specific example of the control method of the fuel injection device 1 will be described. In the following, as an example, when a drive current C1 is supplied to the drive unit A1, the drive unit A1 opens the injection port H by the first valve V1, and when a drive current C2 is supplied to the drive unit A2, the drive unit A2 opens the second flow path F2 by the second valve V2 will be described. That is, when the supply of the drive current C1 to the drive unit A1 is stopped, the drive unit A1 closes the injection port H by the first valve V1. Further, when the supply of the drive current C2 to the drive unit A2 is stopped, the drive unit A2 closes the second flow path F2 by the second valve V2. Further, in the following, as an example, the control method of the fuel injection device 1 when performing main injection will be described. However, this control method may also be applied to other injections such as pre-injection and pilot injection. Further, in the following, as an example, among the controls of the fuel injection device 1, the control involving the opening and closing of the injection port H and the opening and closing of the second flow path F2 will be described as the first control. Further, in the following, as an example, among the controls of the fuel injection device 1, the control involving the opening and closing of the injection port H and not involving the opening and closing of the second flow path F2 will be described as the second control. When the second control is performed, the temporal changes in the injection pressure and injection rate of the fuel in the fuel injection device 1 become almost the same as the temporal changes in the injection pressure and injection rate of the fuel in the conventional fuel injection device. Therefore, comparing the control method of the fuel injection device 1 by the first control with the control method of the fuel injection device 1 by the second control leads to clearly showing the points where the fuel injection device 1 is superior compared to a fuel injection device different from the fuel injection device 1 (for example, a conventional fuel injection device). Therefore, in the following, the control method of the fuel injection device 1 by the first control and the control method of the fuel injection device 1 by the second control will be compared, and the points where the fuel injection device 1 is superior compared to the conventional fuel injection device will be described. In the present embodiment, the injection pressure of the fuel indicates the pressure of the fuel at the outlet of the injection port H. Further, in the present embodiment, the injection rate of the fuel indicates the volume of the fuel flowing out per unit time from the injection port H toward the combustion chamber CC.

[0041] FIG. 4 is a diagram showing an example of each of the opening and closing timings of the injection port H and the second flow path F2 in the fuel injection device 1, the temporal change in the pressure in the first flow path F1, the temporal change in the lift amount of the first valve V1, the temporal change in the injection pressure of the fuel, and the temporal change in the injection rate of the fuel. Here, the lift amount of the first valve V1 is an amount indicating the difference between the reference position of the first valve V1 and the position of the first valve V1 with the position of the first valve V1 in the state of closing the injection port H as the reference position of the first valve V1. That is, the larger the lift amount of the first valve V1, the larger the degree to which the injection port H is open. Note that the position of the first valve V1 is represented by, for example, the position at the tip of the first valve V1, but may be a configuration represented by the position of another part of the first valve V1.

[0042] The horizontal axis of each of the graphs G1 to G4 shown in FIG. 4 indicates the elapsed time during the period when the fuel injection device 1 performs the main injection. However, in the example shown in FIG. 4, the timing at which the injection port H starts to open in the fuel injection device 1 controlled by the first control and the timing at which the injection port H starts to open in the fuel injection device 1 controlled by the second control are made to coincide. Also, in this example, the timing at which the injection port H closes in the fuel injection device 1 controlled by the first control and the timing at which the injection port H closes in the fuel injection device 1 controlled by the second control are made to coincide. By making these timings coincide, the difference between the fuel injection device 1 controlled by the first control and the fuel injection device 1 controlled by the second control is clearly shown in FIG. 4.

[0043] The vertical axis of the graph G1 shown in FIG. 4 indicates the pressure in the first flow path F1. The curve FN1 plotted on the graph G1 shows an example of the temporal change in the pressure in the first flow path F1 when the fuel injection device 1 is controlled by the first control. On the other hand, the curve FX1 plotted on the graph G1 shows an example of the temporal change in the pressure in the first flow path F1 when the fuel injection device 1 is controlled by the second control. Also, on the graph G1, a timing chart TC1 showing the opening and closing timing of the injection port H and a timing chart TC2 showing the opening and closing timing of the second flow path F2 are superimposed.

[0044] The vertical axis of the graph G2 shown in FIG. 4 indicates the lift amount of the first valve V1. The curve FN2 plotted on the graph G2 shows an example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1 is controlled by the first control. On the other hand, the curve FX2 plotted on the graph G2 shows an example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1 is controlled by the second control.

[0045] The vertical axis of the graph G3 shown in FIG. 4 indicates the injection pressure of the fuel. The curve FN3 plotted on the graph G3 shows an example of the temporal change in the injection pressure of the fuel when the fuel injection device 1 is controlled by the first control. On the other hand, the curve FX3 plotted on the graph G3 shows an example of the temporal change in the injection pressure of the fuel when the fuel injection device 1 is controlled by the second control.

[0046] The vertical axis of the graph G4 shown in FIG. 4 indicates the injection rate of the fuel. The curve FN4 plotted on the graph G4 shows an example of the temporal change in the injection rate of the fuel when the fuel injection device 1 is controlled by the first control. On the other hand, the curve FX4 plotted on the graph G4 shows an example of the temporal change in the injection rate of the fuel when the fuel injection device 1 is controlled by the second control.

[0047] In the example shown in FIG. 4, the fuel injection device 1 controlled by the first control waits with the injection port H and the second flow path F2 closed until the timing t1. Then, at the timing t1, the fuel injection device 1 starts to open the second flow path F2. As a result, as shown by the curve FN1, in the fuel injection device 1, the pressure in the first flow path F1 starts to decrease at the timing t1. This is because fuel starts to flow from the first flow path F1 to the second flow path F2 at the timing t1.

[0048] Thereafter, in the fuel injection device 1 controlled by the first control, the drive unit A2 starts to move the second valve V2 so that the second flow path F2 closes at the timing t2 when a predetermined first time has elapsed from the timing t1. As a result, in the fuel injection device 1, the pressure in the first flow path F1 starts to rise at the timing t2.

[0049] Then, in the fuel injection device 1 controlled by the first control, at the timing after the timing t2, the pressure in the first flow path F1 instantaneously becomes higher than a predetermined pressure Pb. This is a phenomenon that occurs because the fuel flowing out from the first flow path F1 through the second flow path F2 to the discharge port is blocked by the second valve V2, and as a result, the pressure in the first flow path F1 instantaneously becomes higher than the predetermined pressure Pb due to the water hammer effect generated. More specifically, the fuel flowing from the first flow path F1 through the second flow path F2 to the discharge port is blocked by the second valve V2 in the second flow path F2 at the timing t2. The blocked fuel is compressed according to the flow velocity of the fuel before being blocked. As a result, a water hammer effect occurs, and the pressure in the first flow path F1 starts to rise.

[0050] However, as shown by the curve FN1, the pressure in the first flow path F1 attenuates and oscillates after the timing t2. For this reason, the fuel injection device 1 controlled by the first control starts to open the injection port H at the timing t3. The timing t3 is any timing within the period after the timing t2, during which the pressure in the first flow path F1 rises from a pressure below a predetermined pressure Pb to a pressure exceeding the predetermined pressure Pb, and then the pressure in the first flow path F1 starts to decline again. Here, in FIG. 4, the difference between the highest pressure caused by the water hammer effect among the pressures in the first flow path F1 and the predetermined pressure Pb is indicated by ΔPmax. That is, the fuel injection device 1 sets the timing within the period after the timing t2, during which the pressure in the first flow path F1 reaches (Pb + ΔPmax), as the timing t3, and starts to open the injection port H at the timing t3. In the example shown in FIG. 4, the timing t3 is the timing after the timing t2, when the pressure in the first flow path F1 returns from a pressure below the predetermined pressure Pb to the predetermined pressure Pb.

[0051] The time difference between the timing t2 and the timing t3 is determined, for example, by trial and error through prior tests, experiments, etc., so that the combustion efficiency of the fuel approaches a desired combustion efficiency (e.g., the highest combustion efficiency, etc.). However, it may also be determined based on theoretical calculations, may be determined by simulation, or may be determined by other methods. Since the injection port H starts to open at the timing t3 determined in this way, the fuel in the first flow path F1 starts to be injected into the combustion chamber CC from the injection port H at a pressure higher than the predetermined pressure Pb at the timing t3. For this reason, the injection pressure and injection rate of the fuel also start to rise at the timing t3, as shown by the curves FN3 and FN4 respectively.

[0052] After timing t3, in the fuel injection device 1 controlled by the first control, the drive unit A1 starts to move the first valve V1 so that the injection port H closes at timing t4 when a predetermined second time has elapsed from timing t3. Triggered by the drive unit A1 starting to move the first valve V1, in the fuel injection device 1, within the period from timing t3 to timing t4, the lift amount of the first valve V1 decreases, and the injection pressure and injection rate of the fuel start to decline. Then, at timing t4, in the fuel injection device 1, the lift amount of the first valve V1 becomes 0 [mm], the injection pressure of the fuel becomes 0 [MPa], and the injection rate of the fuel becomes 0 [mm 3 / s]. However, within the period from timing t3 to timing t4, vibrations may be observed in each of the lift amount of the first valve V1, the injection pressure of the fuel, and the injection rate of the fuel. In the example shown in FIG. 4, each of the lift amount of the first valve V1, the injection pressure of the fuel, and the injection rate of the fuel fluctuates in the order of rising, falling, rising, and falling within the period. Therefore, in this example, two peaks appear in the temporal changes of each of the lift amount of the first valve V1, the injection pressure of the fuel, and the injection rate of the fuel. This is a reflection of the influence caused by the pressure in the first flow path F1 decaying and oscillating within the period. Countermeasures against this influence will be described from Modification Example 1 of the embodiment onwards.

[0053] After timing t4, the fuel injection device 1 controlled by the first control waits with the injection port H and the second flow path F2 closed until it starts the next injection of fuel. Therefore, in the fuel injection device 1, the pressure in the first flow path F1 returns to a predetermined pressure Pb until the next injection of fuel starts.

[0054] On the one hand, in the example shown in FIG. 4, as shown in the timing chart TC1, the fuel injection device 1 controlled by the second control waits with the injection port H and the second flow path F2 closed until timing t3. Then, at timing t3, the fuel injection device 1 begins to open the injection port H. Since the injection port H begins to open, the fuel in the first flow path F1 starts to be injected from the injection port H into the combustion chamber CC at a predetermined pressure Pb at timing t3. For this reason, the injection pressure and injection rate of the fuel also begin to increase at timing t3, as shown by curves FX3 and FX4 respectively. As a result, as shown by curve FX1, in the fuel injection device 1, the pressure in the first flow path F1 begins to decrease from the predetermined pressure Pb at timing t3.

[0055] After timing t3, in the fuel injection device 1 controlled by the second control, the drive unit A1 begins to move the first valve V1 so that the injection port H closes at timing t4. Triggered by the drive unit A1 beginning to move the first valve V1, in the fuel injection device 1, within the period from timing t3 to timing t4, the lift amount of the first valve V1 decreases, and the injection pressure and injection rate of the fuel begin to decline. Then, at timing t4, in the fuel injection device 1, the lift amount of the first valve V1 becomes 0 [mm], the injection pressure of the fuel becomes 0 [MPa], and the injection rate of the fuel becomes 0 [mm 3 / s]. Note that in the fuel injection device 1, within the period from timing t3 to timing t4, there is no vibration seen in the lift amount of the first valve V1, the injection pressure of the fuel, or the injection rate of the fuel. This is because the pressure in the first flow path F1 within this period does not vibrate in the fuel injection device 1.

[0056] After timing t4, the fuel injection device 1 controlled by the second control waits with the injection port H and the second flow path F2 closed until it starts the next fuel injection. For this reason, in the fuel injection device 1, the pressure in the first flow path F1 returns to a predetermined pressure Pb until it starts the next fuel injection. After timing t4, in the fuel injection device 1, since the fuel flowing through the first flow path F1 toward the injection port H is blocked by the first valve V1 at timing t4, as shown by the curve FX1, it undergoes damped vibration due to the occurrence of a water hammer effect. However, in the fuel injection device 1, the influence of this damped vibration does not transmit into the combustion chamber CC because the injection port H is closed at timing t4. And in the fuel injection device 1, this damped vibration subsides within the period until it starts the next fuel injection.

[0057] Here, as described above, the fuel injection device 1 controlled by the first control starts injecting fuel into the combustion chamber CC from timing t3 at a pressure higher than the predetermined pressure Pb. Starting to inject fuel at a pressure higher than the predetermined pressure Pb, that is, a pressure higher than the pressure of the high-pressure source 4, cannot be done by the fuel injection device 1 controlled by the second control. In other words, starting to inject fuel at a pressure higher than the predetermined pressure Pb, that is, a pressure higher than the pressure of the high-pressure source 4, cannot be done by a conventional fuel injection device. And as shown by each of graphs G2 to G4, as a result of starting to inject fuel at a pressure higher than the predetermined pressure Pb, the rise of the curve FN2 is steeper and sharper than the rise of the curve FX2, the rise of the curve FN3 is steeper and sharper than the rise of the curve FX3, and the rise of the curve FN4 is steeper and sharper than the rise of the curve FX4.

[0058] That is to say, in the fuel injection device 1, the rise of the lift amount of the first valve V1 becomes steeper and sharper compared with the conventional case, the rise of the fuel injection pressure becomes steeper and sharper compared with the conventional case, and the rise of the fuel injection rate becomes steeper and sharper compared with the conventional case. In other words, in the fuel injection device 1, the injection port H can be opened faster than the conventional fuel injection device, the fuel injection pressure and the injection rate can be increased faster than the conventional fuel injection device, and furthermore, the fuel injection pressure and the injection rate can be increased higher than the conventional fuel injection device. As a result, the fuel injection device 1 can improve the combustion efficiency of the fuel more than the conventional fuel injection device. In addition, the fuel injection device 1 can realize the steepening of the rise of the fuel injection pressure from the timing t3 without using an expensive actuator with high responsiveness such as a piezo element. This indicates that the fuel injection device 1 can also suppress an increase in the manufacturing cost. Naturally, the fuel injection device 1 can further steepen the rise of the fuel injection pressure from the timing t3 by combining it with an actuator with high responsiveness.

[0059] Each of the above-mentioned first time and second time is determined, for example, by trial and error through prior tests, experiments, etc. so that the combustion efficiency of the fuel approaches a desired combustion efficiency (for example, the highest combustion efficiency, etc.), but it may also be determined based on theoretical calculations, may be determined by simulation, or may be determined by other methods.

[0060] Also, ΔPmax, which is the change in pressure that rises due to the water hammer effect in the first flow path F1, the required time from timing t2 until the pressure in the first flow path F1 exceeds a predetermined pressure Pb, the length of the time during which the pressure in the first flow path F1 continues to exceed the predetermined pressure Pb, etc. are determined depending on the flow velocity, flow rate, etc. of the fuel that has flowed from the first flow path F1 through the second flow path F2 to the discharge port. Therefore, the flow velocity, flow rate, etc. of the fuel flowing from the first flow path F1 through the second flow path F2 to the discharge port are determined, for example, by trial and error through prior tests, experiments, etc. so that the combustion efficiency of the fuel approaches a desired combustion efficiency (for example, the highest combustion efficiency, etc.), but may also be determined based on theoretical calculations, may be determined by simulation, or may be determined by other methods.

[0061] <Modification Example 1 of the Embodiment> Hereinafter, Modification Example 1 of the embodiment will be described. In Modification Example 1 of the embodiment, the same reference numerals are given to the same components as in the embodiment, and the description thereof will be omitted. Hereinafter, for convenience of explanation, in order to distinguish the fuel injection device 1 according to Modification Example 1 of the embodiment from the fuel injection device 1 according to the embodiment, it will be described as the fuel injection device 1A.

[0062] In the fuel injection device 1A, compared with the fuel injection device 1, the flow rate of the fuel flowing from the first flow path F1 through the second flow path F2 to the discharge port is increased without changing the flow velocity of the fuel. This can be achieved, for example, by increasing the diameter of the second flow path F2, forming the second flow path F2 in a tapered shape, configuring the second flow path F2 with a plurality of pipe lines, etc. Hereinafter, as an example, a case where the diameter of the second flow path F2 provided in the fuel injection device 1A is larger than the diameter of the second flow path F2 provided in the fuel injection device 1 will be described. In this case, the second valve V2 provided in the fuel injection device 1A also becomes larger compared with the second valve V2 provided in the fuel injection device 1. As a result, in the fuel injection device 1A, the flow rate of the fuel blocked by the second valve V2 at the timing t2 increases, and the length of the time during which the pressure in the first flow path F1 continuously exceeds the predetermined pressure Pb due to the water hammer action becomes longer. Thereby, the fuel injection device 1A can suppress the pressure in the first flow path F1 from decaying and vibrating during the period from the timing t3 to the timing t4.

[0063] FIG. 5 is a diagram showing an example of each of the opening / closing timing of the injection port H and the second flow path F2 in the fuel injection device 1A, the temporal change of the pressure in the first flow path F1, the temporal change of the lift amount of the first valve V1, the temporal change of the injection pressure of the fuel, and the temporal change of the injection rate of the fuel.

[0064] The graph G1 shown in FIG. 5 is the same graph as the graph G1 shown in FIG. 4, except that the curve FN11 is plotted instead of the curve FN1. This is because the temporal change of the pressure in the first flow path F1 in the fuel injection device 1A controlled by the second control is the same as the temporal change of the pressure in the first flow path F1 in the fuel injection device 1 controlled by the second control. Hereinafter, for convenience of explanation, the graph G1 shown in FIG. 5 will be described by referring to it as the graph G11. Here, the curve FN11 shows another example of the temporal change of the pressure in the first flow path F1 when the fuel injection device 1A is controlled by the first control.

[0065] The graph G2 shown in FIG. 5 is the same graph as the graph G2 shown in FIG. 4, except that the curve FN21 is plotted instead of the curve FN2. This is because the temporal change in the lift amount of the first valve V1 in the fuel injection device 1A controlled by the second control is the same as the temporal change in the lift amount of the first valve V1 in the fuel injection device 1 controlled by the second control. Hereinafter, for convenience of explanation, the graph G2 shown in FIG. 5 will be described by referring to it as the graph G21. Here, the curve FN21 shows another example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1A is controlled by the first control.

[0066] The graph G3 shown in FIG. 5 is the same graph as the graph G3 shown in FIG. 4, except that the curve FN31 is plotted instead of the curve FN3. This is because the temporal change in the injection pressure of the fuel in the fuel injection device 1A controlled by the second control is the same as the temporal change in the injection pressure of the fuel in the fuel injection device 1 controlled by the second control. Hereinafter, for convenience of explanation, the graph G3 shown in FIG. 5 will be described by referring to it as the graph G31. Here, the curve FN31 shows another example of the temporal change in the injection pressure of the fuel when the fuel injection device 1A is controlled by the first control.

[0067] The graph G4 shown in FIG. 5 is the same graph as the graph G4 shown in FIG. 4, except that the curve FN41 is plotted instead of the curve FN4. This is because the temporal change in the injection rate of the fuel in the fuel injection device 1A controlled by the second control is the same as the temporal change in the injection rate of the fuel in the fuel injection device 1 controlled by the second control. Hereinafter, for convenience of explanation, the graph G4 shown in FIG. 5 will be described by referring to it as the graph G41. Here, the curve FN41 shows another example of the temporal change in the injection rate of the fuel when the fuel injection device 1A is controlled by the first control.

[0068] As shown by the curve FN11, in the fuel injection device 1A, within the period from timing t3 to timing t4, the pressure in the first flow path F1 only rises and then falls, without vibration. And throughout almost the entire region within this period, the pressure in the first flow path F1 is higher than a predetermined pressure Pb. This is because as a result of the fuel flow rate through the second flow path F2 in the fuel injection device 1A increasing more than the fuel flow rate through the second flow path F2 in the fuel injection device 1, the length of time during which the pressure in the first flow path F1 continuously exceeds the predetermined pressure Pb due to the water hammer effect becomes longer. As a result, as shown by the curves FN21, FN31, and FN41, in the fuel injection device 1A, within this period, the lift amount of the first valve V1, the injection pressure of the fuel, and the injection rate of the fuel also stop vibrating and only rise and then fall.

[0069] Also, as shown by the graph G11, the fuel injection device 1A controlled by the first control can also start injecting fuel into the combustion chamber CC from timing t3 at a pressure higher than the predetermined pressure Pb. And as shown by each of the graphs G21 to G41, as a result of starting to inject fuel at a pressure higher than the predetermined pressure Pb, the rise of the curve FN21 is steeper and sharper than the rise of the curve FX2, the rise of the curve FN31 is steeper and sharper than the rise of the curve FX3, and the rise of the curve FN41 is steeper and sharper than the rise of the curve FX4.

[0070] That is to say, also in the fuel injection device 1A, the rise of the lift amount of the first valve V1 becomes steeper and sharper compared with the conventional one, the rise of the fuel injection pressure becomes steeper and sharper compared with the conventional one, and the rise of the fuel injection rate becomes steeper and sharper compared with the conventional one. In other words, also in the fuel injection device 1A, the injection port H can be opened faster than the conventional fuel injection device, the fuel injection pressure and the injection rate can be increased faster than the conventional fuel injection device, and furthermore, the fuel injection pressure and the injection rate can be increased higher than the conventional fuel injection device. As a result, in addition to being able to improve the combustion efficiency of the fuel more than the conventional fuel injection device, the fuel injection device 1A can suppress the influence of the pressure vibration in the first flow path F1 caused by the water hammer action from being transmitted into the combustion chamber CC.

[0071] As described above, the fuel injection device 1 and the fuel injection device 1A are fuel injection devices that inject fuel into the combustion chamber CC of the internal combustion engine EG, and include an injection port H that injects fuel into the combustion chamber CC, a high-pressure source 4 that supplies fuel at a predetermined pressure Pb and is connected to the injection port H, a first flow path F1 through which fuel is supplied from the high-pressure source 4, a first valve V1 provided in the first flow path F1 that opens and closes the injection port H, a second flow path F2 connected to the first flow path F1 through which fuel is supplied from the first flow path F1, and a second valve V2 provided in the second flow path F2 that opens and closes the second flow path F2. Thereby, during the period when the pressure in the first flow path F1 is higher than the predetermined pressure Pb, the first valve V1 opens the injection port H, and fuel can be injected into the combustion chamber CC at a pressure higher than the predetermined pressure Pb. As a result, the fuel injection device 1 and the fuel injection device 1A can improve the combustion efficiency of the fuel more.

[0072] <Modification Example 2 of the Embodiment> Next, Modification Example 2 of the embodiment will be described. In Modification Example 2 of the embodiment, the same reference numerals are given to the same components as in the embodiment, and the description thereof will be omitted. Hereinafter, for convenience of explanation, in order to distinguish the fuel injection device 1 according to Modification Example 1 of the embodiment from the fuel injection device 1 according to the embodiment and the fuel injection device 1A according to Modification Example 1 of the embodiment, it will be described as the fuel injection device 1B.

[0073] In Modification Example 2 of the embodiment, as shown in FIG. 6, in addition to the first flow path F1, the injection port H, the first valve V1, the drive unit A1, the second flow path F2, the second valve V2, and the drive unit A2, the fuel injector 2 includes a third valve V3 and a drive unit A3. FIG. 6 is a diagram showing another example of the configuration of the fuel injection device 1B. Further, in Modification Example 2 of the embodiment, as shown in FIG. 7, in addition to the storage unit 32, the first valve drive circuit 33, the second valve drive circuit 34, and the control unit 36, the ECU 3 includes a third valve drive circuit 35. FIG. 7 is a diagram showing another example of the functional configuration of the ECU 3. In FIG. 6, the configuration of the fuel injector 2 is realized by connecting two fuel injectors in series. However, the configuration of the fuel injector 2 may be realized by other methods instead of connecting two fuel injectors in series.

[0074] The third valve V3 is provided in the first flow path F1 and is located upstream of the first valve V1 in the first flow path F1 among the portions of the first flow path F1, and is provided in a portion PP2 that is located downstream of the connection portion PP1 between the first flow path F1 and the second flow path F2 in the first flow path F1 among the portions of the first flow path F1. That is, the third valve V3 opens and closes the first flow path F1 in the portion PP2. For this reason, in the first flow path F1, when the first valve V1 closes the injection port H and the third valve V3 closes the first flow path F1, a space S in which fuel is held is formed. Therefore, hereinafter, for convenience of explanation, among the spaces in the first flow path F1, when the first valve V1 closes the injection port H and the third valve V3 closes the first flow path F1, the space closed by the first valve V1 and the third valve V3 will be described as the space S. When the first valve V1 closes the injection port H and the third valve V3 opens the first flow path F1, fuel is supplied from the high-pressure source 4 through the first flow path F1 and accumulated in the space S. For this reason, the pressure in the space S is maintained when the first valve V1 closes the injection port H and the third valve V3 closes the first flow path F1. For this reason, the space S can also be interpreted as a pressure accumulation portion that accumulates pressure.

[0075] In the example shown in FIG. 6, the third valve V3 is a nozzle needle. Note that the third valve V3 may be any member as long as it is a member that can open and close the portion PP2 instead of the nozzle needle.

[0076] The third valve V3 closes the first flow path F1 by closing the portion PP2. More specifically, when the ECU3 does not drive the drive unit A3, the third valve V3 does not move while closing the portion PP2. As a result, the third valve V3 continuously closes the first flow path F1 in this case. On the other hand, when the ECU3 drives the drive unit A3, the third valve V3 moves in a direction to open the portion PP2. As a result, the third valve V3 opens the first flow path F1 in this case.

[0077] The drive unit A3 causes the third valve V3 to open and close the partial PP2. The drive unit A3 has, for example, a solenoid, a piezo element, etc. as an actuator for driving the third valve V3. When the drive unit A3 is not driven by the ECU3, the pressure of the fuel supplied through the pipeline connected to the first flow path F1 (i.e., a predetermined pressure Pb) presses the third valve V3 against the partial PP2 and continues to block the partial PP2. That is, in this case, the drive unit A3 continues to close the first flow path F1 by the third valve V3. Here, this pipeline connects the first flow path F1 and a discharge port through which the fuel passing through this pipeline is discharged. This discharge port is connected to, for example, a fuel tank (this fuel tank may or may not be connected to the high-pressure source 4) via a pipeline not shown. Therefore, the fuel flowing out from this discharge port finally returns to the fuel tank. Note that the configuration after this discharge port may be any configuration instead. Therefore, further detailed description of the configuration after this discharge port is omitted. On the other hand, when the drive unit A3 is driven by the ECU3, the pressure of the fuel supplied through this pipeline (i.e., a predetermined pressure Pb) is decompressed by opening a valve provided in the drive unit A3, and the third valve V3 is moved in the direction of opening the partial PP2. That is, in this case, the drive unit A3 opens the first flow path F1 by the third valve V3. Note that the structure and operation of the opening and closing of the third valve V3 may be known structures and operations, or may be structures and operations to be developed in the future, so further detailed description is omitted.

[0078] The third valve drive circuit 35 supplies a drive current for driving the drive unit A3 that opens and closes the third valve V3 to the drive unit A3. Here, the control unit 36 controls the third valve drive circuit 35 and causes the drive unit A3 to open and close the first flow path F1 by the third valve V3 according to the timing pre-stored in the storage unit 32.

[0079] <Control Method of Fuel Injection Device> Hereinafter, with reference to FIG. 8, a specific example of the control method of the fuel injection device 1B will be described. In the following, as an example, when the drive current C1 is supplied to the drive unit A1, the drive unit A1 opens the injection port H by the first valve V1, and when the drive current C2 is supplied to the drive unit A2, the drive unit A2 opens the second flow path F2 by the second valve V2. When the drive current C3 is supplied to the drive unit A3, the case where the drive unit A3 opens the first flow path F1 by the third valve V3 will be described. That is, when the supply of the drive current C1 to the drive unit A1 is stopped, the drive unit A1 closes the injection port H by the first valve V1. Further, when the supply of the drive current C2 to the drive unit A2 is stopped, the drive unit A2 closes the second flow path F2 by the second valve V2. Further, when the supply of the drive current C3 to the drive unit A3 is stopped, the drive unit A3 closes the first flow path F1 by the third valve V3. Further, in the following, as an example, the control method of the fuel injection device 1B in the case of performing main injection will be described. However, this control method may also be applied to other injections such as pre-injection and pilot injection. Further, in the following, as an example, among the controls of the fuel injection device 1B, the control involving the opening and closing of the injection port H, the opening and closing of the first flow path F1, and the opening and closing of the second flow path F2 will be described as the third control. Further, in the following, as an example, among the controls of the fuel injection device 1B, the control involving the opening and closing of the injection port H and the opening and closing of the first flow path F1 and not involving the opening and closing of the second flow path F2 will be described as the fourth control. When the fourth control is performed, the temporal changes in the injection pressure and injection rate of the fuel in the fuel injection device 1B are substantially the same as the temporal changes in the injection pressure and injection rate of the fuel in a conventional fuel injection device (for example, a fuel injection device known as TAIZAC (series 2-valve instantaneous switching injector)) that does not include a valve corresponding to the second valve V2 and includes valves corresponding to the first valve V1 and the third valve V3, respectively. Therefore, comparing the control method of the fuel injection device 1B by the third control with the control method of the fuel injection device 1B by the fourth control leads to clearly showing the advantages of the fuel injection device 1B compared to a fuel injection device different from the fuel injection device 1B (for example, TAIZAC, etc.).Therefore, in the following, the control method of the fuel injection device 1B by the third control and the control method of the fuel injection device 1B by the fourth control will be compared, and the advantages of the fuel injection device 1B over the conventional fuel injection device will be explained.

[0080] FIG. 8 is a diagram showing an example of each of the opening / closing timings of the injection port H, the first flow path F1, and the second flow path F2 in the fuel injection device 1B, the temporal change in the pressure in the first flow path F1, the temporal change in the pressure in the space S, the temporal change in the lift amount of the first valve V1, the temporal change in the fuel injection pressure, and the temporal change in the fuel injection rate.

[0081] The horizontal axis of each of the graphs G1A to G5A shown in FIG. 8 indicates the elapsed time during the period when the main injection is performed by the fuel injection device 1. However, in the example shown in FIG. 8, the timing when the injection port H starts to open in the fuel injection device 1B controlled by the third control and the timing when the injection port H starts to open in the fuel injection device 1B controlled by the fourth control are made to coincide. Also, in this example, the timing when the injection port H closes in the fuel injection device 1B controlled by the third control and the timing when the injection port H closes in the fuel injection device 1B controlled by the fourth control are made to coincide. By making these timings coincide, the difference between the fuel injection device 1B controlled by the third control and the fuel injection device 1B controlled by the fourth control is clearly shown in FIG. 8.

[0082] The vertical axis of the graph G1A shown in FIG. 8 indicates the pressure in the first flow path F1. The curve FN1A plotted on the graph G1A shows an example of the temporal change in the pressure in the first flow path F1 when the fuel injection device 1B is controlled by the third control. On the other hand, the curve FX1A plotted on the graph G1A shows an example of the temporal change in the pressure in the first flow path F1 when the fuel injection device 1B is controlled by the fourth control. Also, on the graph G1A, the timing chart TC1A showing the opening / closing timing of the first flow path F1 and the timing chart TC2A showing the opening / closing timing of the second flow path F2 are superimposed.

[0083] The vertical axis of the graph G2A shown in FIG. 8 indicates the pressure within the space S. The curve FN2A plotted on the graph G2A shows an example of the temporal change in the pressure within the space S when the fuel injection device 1B is controlled by the third control. On the other hand, the curve FX2A plotted on the graph G2A shows an example of the temporal change in the pressure within the space S when the fuel injection device 1B is controlled by the fourth control.

[0084] The vertical axis of the graph G3A shown in FIG. 8 indicates the lift amount of the first valve V1. The curve FN3A plotted on the graph G3A shows an example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1B is controlled by the third control. On the other hand, the curve FX3A plotted on the graph G3A shows an example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1B is controlled by the fourth control. Also, a timing chart TC3A indicating the opening and closing timing of the injection port H is superimposed on the graph G3A.

[0085] The vertical axis of the graph G4A shown in FIG. 8 indicates the fuel injection pressure. The curve FN4A plotted on the graph G4A shows an example of the temporal change in the fuel injection pressure when the fuel injection device 1B is controlled by the third control. On the other hand, the curve FX4A plotted on the graph G4A shows an example of the temporal change in the fuel injection pressure when the fuel injection device 1B is controlled by the fourth control.

[0086] The vertical axis of the graph G5A shown in FIG. 8 indicates the fuel injection rate. The curve FN5A plotted on the graph G5A shows an example of the temporal change in the fuel injection rate when the fuel injection device 1B is controlled by the third control. On the other hand, the curve FX5A plotted on the graph G5A shows an example of the temporal change in the fuel injection rate when the fuel injection device 1B is controlled by the fourth control.

[0087] In the example shown in FIG. 8, the fuel injection device 1B controlled by the third control waits with the injection port H, the first flow path F1, and the second flow path F2 closed until timing t5. At this time, the pressure in the space S is maintained at a predetermined pressure P0 until timing t5. The predetermined pressure P0 may be any pressure as long as it is higher than 0 [MPa] and lower than the predetermined pressure Pb. Then, at timing t5, the fuel injection device 1B starts to open the second flow path F2. As a result, as shown by the curve FN1A, in the fuel injection device 1B, the pressure in the first flow path F1 starts to decrease at timing t5. This is because fuel starts to flow from the first flow path F1 to the second flow path F2 at timing t5.

[0088] Thereafter, in the fuel injection device 1B controlled by the third control, the drive unit A2 starts to move the second valve V2 so that the second flow path F2 closes at timing t6 when a predetermined third time has elapsed from timing t5. As a result, in the fuel injection device 1, the pressure in the first flow path F1 starts to increase at timing t6.

[0089] Then, in the fuel injection device 1B controlled by the third control, at timings after timing t6, the pressure in the first flow path F1 instantaneously becomes higher than the predetermined pressure Pb. This is a phenomenon that occurs because the fuel flowing out from the first flow path F1 through the second flow path F2 to the discharge port is blocked by the second valve V2, and as a result, the pressure in the first flow path F1 instantaneously becomes higher than the predetermined pressure Pb due to the water hammer effect generated.

[0090] However, as shown by the curve FN1A, the pressure in the first flow path F1 attenuates and oscillates after the timing t6. Therefore, the fuel injection device 1B controlled by the third control starts to open the first flow path F1 at the timing t7. The timing t7 can be any timing within the period after the timing t6, as long as it is the period during which the pressure in the first flow path F1 rises from a pressure less than the predetermined pressure Pb to a pressure exceeding the predetermined pressure Pb, and then until the pressure in the first flow path F1 starts to decrease again. Here, in FIG. 8 as well, the difference between the highest pressure caused by the water hammer effect among the pressures in the first flow path F1 and the predetermined pressure Pb is indicated by ΔPmax. That is, the fuel injection device 1B sets the timing within the period after the timing t6, during which the pressure in the first flow path F1 reaches (Pb + ΔPmax), as the timing t7, and starts to open the first flow path F1 at the timing t7.

[0091] The time difference between the timing t6 and the timing t7 is determined, for example, by trial and error through prior tests, experiments, etc., so that the fuel combustion efficiency approaches the desired combustion efficiency (e.g., the highest combustion efficiency, etc.). However, it may also be determined based on theoretical calculations, or by simulation, or by other methods. Since the first flow path F1 starts to open at the timing t7 determined in this way, the fuel in the first flow path F1 starts to be supplied from the first flow path F1 into the space S at the timing t7. Therefore, the pressure in the space S also starts to rise at the timing t7, as shown by the curve FN2A. Here, the pressure in the first flow path F1 exceeds the predetermined pressure Pb due to the aforementioned water hammer effect after the timing t7. Therefore, after the timing t7, the fuel in the first flow path F1 is supplied from the first flow path F1 into the space S by a pressure higher than the predetermined pressure Pb. Note that the timing t7 may be adjusted so that the fuel in the first flow path F1 is supplied into the space S at a pressure higher than the predetermined pressure Pb at the timing t7.

[0092] Here, as described above, the pressure in the space S is maintained by closing both the injection port H and the first flow path F1. Therefore, when both the injection port H and the first flow path F1 are closed in a state where the pressure in the space S is higher than a predetermined pressure Pb after the timing t7, the pressure in the space S is maintained at a pressure higher than the predetermined pressure Pb.

[0093] After the timing t7, in the fuel injection device 1B controlled by the third control, the drive unit A3 starts to move the third valve V3 so that the first flow path F1 closes at the timing t9 when a predetermined fourth time has elapsed from the timing t7.

[0094] Also, after the timing t7, in the fuel injection device 1B controlled by the third control, the drive unit A1 starts to move the first valve V1 so that the injection port H opens at the timing t8 when a predetermined fifth time has elapsed from the timing t7. Note that the timing t8 may be a timing after the timing t7, before the timing t9, or the same as the timing t9 as long as it is a timing after the timing t7. In the example shown in FIG. 8, the timing t8 is a timing before the timing t9. Since the fuel injection device 1B opens the injection port H at the timing t8, fuel can be injected from the injection port H into the combustion chamber CC at a pressure higher than the predetermined pressure Pb. In this example, at the timing t8, the fuel injection device 1B can inject fuel from the injection port H into the combustion chamber CC at a pressure of (Pb + ΔPmax).

[0095] After timing t8, in the fuel injection device 1B controlled by the third control, the drive unit A1 starts to move the first valve V1 so that the injection port H closes at timing t10 when a predetermined sixth time has elapsed since timing t8. Triggered by the drive unit A1 starting to move the first valve V1, in the fuel injection device 1B, within the period from timing t8 to timing t10, the lift amount of the first valve V1 decreases, and the fuel injection pressure and injection rate start to decline. Then, at timing t10, in the fuel injection device 1B, the lift amount of the first valve V1 becomes 0 [mm], the fuel injection pressure becomes 0 [MPa], and the fuel injection rate becomes 0 [mm 3 / s]. Note that during the period from timing t8 to timing t10, there is no vibration observed in the lift amount of the first valve V1, the fuel injection pressure, and the fuel injection rate respectively. This is because the first flow path F1 is closed by the third valve V3 at timing t9, so the influence of the damped vibration of the pressure in the first flow path F1 after timing t9 is not transmitted into the space S. Also, during the period from timing t9 to timing t10, the fuel in the space S is not supplied from the high-pressure source 4 to the space S through the first flow path F1, so it decreases over time. As a result, the pressure in the space S also decreases as it approaches from timing t9 to timing t10. In the example shown in Fig. 8, at timing t10, the pressure in the space S is a predetermined pressure P0. Thus, since the pressure in the space S decreases during the period from timing t9 to timing t10, in the fuel injection device 1B, reverse delta injection is realized as shown by the curve FN4A and the curve FN5A. Thereby, the fuel injection device 1B can suppress the generation of an overly rich air-fuel mixture mass, etc., and can more surely improve the combustion efficiency of the fuel.

[0096] After timing t10, the fuel injection device 1B controlled by the third control waits with the injection port H, the first flow path F1, and the second flow path F2 all closed until it starts the next fuel injection. For this reason, in the fuel injection device 1B, the pressure in the first flow path F1 returns to a predetermined pressure Pb until it starts the next fuel injection. Also, in the fuel injection device 1B, the pressure in the space S is maintained at a predetermined pressure P0 until it starts the next fuel injection.

[0097] On the other hand, in the example shown in FIG. 8, as shown in the timing chart TC1A, the fuel injection device 1B controlled by the fourth control waits with the injection port H, the first flow path F1, and the second flow path F2 all closed until timing t7. Then, at timing t7, the fuel injection device 1 starts to open the first flow path F1. Since the first flow path F1 starts to open, the fuel in the first flow path F1 is supplied from the first flow path F1 into the space S by a predetermined pressure Pb at timing t7. For this reason, the pressure in the space S also starts to rise at timing t7 as shown by the curve FX2A.

[0098] Here, after timing t7, when both the injection port H and the first flow path F1 are closed while the pressure in the space S has reached the predetermined pressure Pb, the pressure in the space S is maintained at the predetermined pressure Pb.

[0099] After timing t7, in the fuel injection device 1B controlled by the fourth control, the drive unit A3 starts to move the third valve V3 so that the first flow path F1 closes at timing t9.

[0100] Also, after timing t7, in the fuel injection device 1B controlled by the fourth control, the drive unit A1 starts to move the first valve V1 so that the injection port H opens at timing t8. Since the fuel injection device 1B opens the injection port H at timing t8, the fuel is injected from the injection port H into the combustion chamber CC by a predetermined pressure Pb.

[0101] After timing t8, in the fuel injection device 1B controlled by the fourth control, the drive unit A1 starts to move the first valve V1 so that the injection port H closes at timing t10. Triggered by the drive unit A1 starting to move the first valve V1, in the fuel injection device 1B, within the period from timing t8 to timing t10, the lift amount of the first valve V1 decreases, and the injection pressure and injection rate of the fuel start to decline. Then, at timing t10, in the fuel injection device 1B, the lift amount of the first valve V1 becomes 0 [mm], the injection pressure of the fuel becomes 0 [MPa], and the injection rate of the fuel becomes 0 [mm 3 / s]. During the period from timing t9 to timing t10, since fuel is not supplied from the high-pressure source 4 to the space S through the first flow path F1, the fuel in the space S decreases with the passage of time. As a result, the pressure in the space S also decreases as it approaches from timing t9 to timing t10. In the example shown in FIG. 8, at timing t10, the pressure in the space S is a predetermined pressure P0. Thus, since the pressure in the space S decreases within the period from timing t9 to timing t10, reverse delta injection is also realized in the fuel injection device 1B as shown by the curve FN4A and the curve FN5A.

[0102] After timing t10, the fuel injection device 1B controlled by the fourth control waits with the injection port H, the first flow path F1, and the second flow path F2 each closed until it starts the next injection of fuel. For this reason, in the fuel injection device 1B, the pressure in the first flow path F1 returns to a predetermined pressure Pb until the next injection of fuel starts. Also, in the fuel injection device 1B, the pressure in the space S is held at the predetermined pressure P0 until the next injection of fuel starts.

[0103] Here, as described above, the fuel injection device 1 controlled by the third control starts injecting fuel into the combustion chamber CC from the timing t8 at a pressure higher than the predetermined pressure Pb. Starting to inject fuel at a pressure higher than the predetermined pressure Pb, that is, a pressure higher than the pressure of the high-pressure source 4, cannot be done with the fuel injection device 1 controlled by the fourth control. In other words, starting to inject fuel at a pressure higher than the predetermined pressure Pb, that is, a pressure higher than the pressure of the high-pressure source 4, cannot be done with a conventional fuel injection device. And as shown in each of graphs G2A to G5A, as a result of starting to inject fuel at a pressure higher than the predetermined pressure Pb, the rise of curve FN2A has become steeper and sharper than the rise of curve FX2A, the rise of curve FN3A has become steeper and sharper than the rise of curve FX3A, the rise of curve FN4A has become steeper and sharper than the rise of curve FX4A, and the rise of curve FN5A has become steeper and sharper than the rise of curve FX5A.

[0104] That is to say, in the fuel injection device 1B, even when control involving the opening and closing of the third valve V3 is performed, the rise of the lift amount of the first valve V1 becomes steeper and sharper compared to the conventional case, the rise of the fuel injection pressure becomes steeper and sharper compared to the conventional case, and the rise of the fuel injection rate becomes steeper and sharper compared to the conventional case. In other words, in the fuel injection device 1B, the injection port H can be opened faster than in the conventional fuel injection device, the fuel injection pressure and the injection rate can be increased faster than in the conventional fuel injection device, and furthermore, the fuel injection pressure and the injection rate can be increased higher than in the conventional fuel injection device. As a result, the fuel injection device 1B can improve the combustion efficiency of the fuel more than the conventional fuel injection device. In addition, the fuel injection device 1B can achieve the steepening of the rise of the fuel injection pressure from the timing t8 without using an expensive actuator with high responsiveness such as a piezo element. This indicates that the fuel injection device 1 can also suppress an increase in the manufacturing cost. Naturally, the fuel injection device 1B can further steepen the rise of the fuel injection pressure from the timing t8 by combining it with an actuator with high responsiveness.

[0105] Each of the aforementioned third hour to sixth hour is determined, for example, by trial and error through prior tests, experiments, etc. so that the combustion efficiency of the fuel approaches a desired combustion efficiency (e.g., the highest combustion efficiency, etc.), but it may also be determined based on theoretical calculations, may be determined by simulation, or may be determined by other methods. However, the magnitude of the predetermined pressure P0 is determined according to the length of the sixth hour. The longer the sixth hour, the lower the predetermined pressure P0. On the other hand, the shorter the sixth hour, the higher the predetermined pressure P0.

[0106] <Modification Example 3 of the Embodiment> Next, Modification Example 3 of the embodiment will be described. Modification Example 3 of the embodiment is a modification of Modification Example 2 of the embodiment. In Modification Example 3 of the embodiment, the same reference numerals are given to the same components as those in Modification Example 2 of the embodiment, and the description thereof will be omitted. Hereinafter, for convenience of explanation, in order to distinguish the fuel injection device 1B according to Modification Example 3 of the embodiment from the fuel injection device 1B according to Modification Example 2 of the embodiment, it will be described as the fuel injection device 1C.

[0107] In the fuel injection device 1C, compared with the fuel injection device 1B, the flow rate of the fuel flowing from the first flow path F1 through the second flow path F2 to the discharge port is increased without changing the flow velocity of the fuel. Hereinafter, as an example, the case where the diameter of the second flow path F2 included in the fuel injection device 1C is larger than the diameter of the second flow path F2 included in the fuel injection device 1B will be described. In this case, the second valve V2 included in the fuel injection device 1C also becomes larger compared with the second valve V2 included in the fuel injection device 1B. As a result, in the fuel injection device 1C, the flow rate of the fuel blocked by the second valve V2 at the timing t6 increases, and the length of the time during which the pressure in the first flow path F1 continues to exceed the predetermined pressure Pb due to the water hammer action becomes longer.

[0108] FIG. 9 is a diagram showing an example of each of the opening / closing timings of the injection port H, the first flow path F1, and the second flow path F2 in the fuel injection device 1C, the temporal change of the pressure in the first flow path F1, the temporal change of the pressure in the space S, the temporal change of the lift amount of the first valve V1, the temporal change of the injection pressure of the fuel, and the temporal change of the injection rate of the fuel.

[0109] The graph G1A shown in FIG. 9 is the same graph as the graph G1A shown in FIG. 8, except that the curve FN11A is plotted instead of the curve FN1A. This is because the temporal change in the pressure in the first flow path F1 in the fuel injection device 1C controlled by the fourth control is the same as the temporal change in the pressure in the first flow path F1 in the fuel injection device 1B controlled by the fourth control. Hereinafter, for convenience of explanation, the graph G1A shown in FIG. 9 will be described by referring to it as the graph G11A. Here, the curve FN11A shows another example of the temporal change in the pressure in the first flow path F1 when the fuel injection device 1C is controlled by the third control.

[0110] The graph G2A shown in FIG. 9 is the same graph as the graph G2A shown in FIG. 8, except that the curve FN21A is plotted instead of the curve FN2A. This is because the temporal change in the pressure in the space S in the fuel injection device 1C controlled by the fourth control is the same as the temporal change in the pressure in the space S in the fuel injection device 1B controlled by the fourth control. Hereinafter, for convenience of explanation, the graph G2A shown in FIG. 9 will be described by referring to it as the graph G21A. Here, the curve FN21A shows another example of the temporal change in the pressure of the space S when the fuel injection device 1C is controlled by the third control.

[0111] The graph G3A shown in FIG. 9 is the same graph as the graph G3A shown in FIG. 8, except that the curve FN31A is plotted instead of the curve FN3A. This is because the temporal change in the lift amount of the first valve V1 in the fuel injection device 1C controlled by the fourth control is the same as the temporal change in the lift amount of the first valve V1 in the fuel injection device 1B controlled by the fourth control. Hereinafter, for convenience of explanation, the graph G3A shown in FIG. 9 will be described by referring to it as the graph G31A. Here, the curve FN31A shows another example of the temporal change in the lift amount of the first valve V1 when the fuel injection device 1C is controlled by the third control.

[0112] The graph G4A shown in FIG. 9 is the same graph as the graph G4A shown in FIG. 8, except that the curve FN41A is plotted instead of the curve FN4A. This is because the temporal change in the injection pressure of the fuel in the fuel injection device 1C controlled by the fourth control is the same as the temporal change in the injection pressure of the fuel in the fuel injection device 1B controlled by the fourth control. Hereinafter, for convenience of explanation, the graph G4A shown in FIG. 9 will be described by referring to it as the graph G41A. Here, the curve FN41A shows another example of the temporal change in the injection pressure of the fuel when the fuel injection device 1C is controlled by the third control.

[0113] The graph G5A shown in FIG. 9 is the same graph as the graph G5A shown in FIG. 8, except that the curve FN51A is plotted instead of the curve FN5A. This is because the temporal change in the injection rate of the fuel in the fuel injection device 1C controlled by the fourth control is the same as the temporal change in the injection rate of the fuel in the fuel injection device 1B controlled by the fourth control. Hereinafter, for convenience of explanation, the graph G5A shown in FIG. 9 will be described by referring to it as the graph G51A. Here, the curve FN51A shows another example of the temporal change in the injection rate of the fuel when the fuel injection device 1C is controlled by the third control.

[0114] As shown by the curve FN11A, in the fuel injection device 1C, within the period from timing t8 to timing t10, the pressure in the first flow path F1 only rises and then falls, without vibration. And throughout almost the entire area within this period, the pressure in the first flow path F1 is higher than a predetermined pressure Pb. Note that in the fuel injection device 1C, when the first flow path F1 is closed, the influence of the pressure in the first flow path F1 does not reach the space S and the combustion chamber CC respectively. For this reason, the ways of the temporal changes of the pressure in the space S, the lift amount of the first valve V1, the fuel injection pressure, and the fuel injection rate in the fuel injection device 1C are the same as those of the pressure in the space S, the lift amount of the first valve V1, the fuel injection pressure, and the fuel injection rate in the fuel injection device 1B. However, in the fuel injection device 1C, by adjusting the flow velocity, flow rate, etc. of the fuel flowing through the second flow path F2, the momentary (instant to the extent that it has no influence on the pressure resistance) increase amplitude of the pressure in the first flow path F1 can be further increased. As a result, the fuel injection device 1C can inject a large amount of fuel without smoke and can increase the torque and output of the internal combustion engine EG. For example, when the fuel injection device 1C is applied to an automotive engine, it can generate a large torque without smoke by ultra-high pressure injection during the acceleration phase when overtaking. Also, for example, when the fuel injection device 1C is applied to a power generation engine, it can inject a large amount of fuel without smoke when the demand for electricity suddenly increases and can suppress the decrease in the rotational speed of the power generation engine. Note that such a momentary increase amplitude of the pressure in the first flow path F1 can be increased as the diameter of the second flow path F2 provided in the fuel injection device 1C is increased, as shown in this example. That is, since the fuel injection device 1C has a larger diameter of the second flow path F2 than the fuel injection device 1B, by adjusting the flow velocity, flow rate, etc. of the fuel flowing through the second flow path F2, the momentary increase amplitude of the pressure in the first flow path F1 can be made even larger than that of the fuel injection device 1B.

[0115] Also, as shown in Graphs G21A to G51A, the fuel injection device 1C controlled by the third control can also start injecting fuel into the combustion chamber CC from timing t8 at a pressure higher than a predetermined pressure Pb. Then, as shown in each of Graphs G41A and G51A, as a result of starting to inject fuel at a pressure higher than the predetermined pressure Pb, the rise of curve FN31A becomes steeper and sharper than the rise of curve FX3A, the rise of curve FN41A becomes steeper and sharper than the rise of curve FX4A, and the rise of curve FN51A becomes steeper and sharper than the rise of curve FX5A.

[0116] This means that even in the fuel injection device 1C, the rise of the lift amount of the first valve V1 becomes steeper and sharper compared to the conventional case, the rise of the fuel injection pressure becomes steeper and sharper compared to the conventional case, and the rise of the fuel injection rate becomes steeper and sharper compared to the conventional case. In other words, even in the fuel injection device 1C, the injection port H can be opened faster than the conventional fuel injection device, the fuel injection pressure and the injection rate can be increased faster than the conventional fuel injection device, and furthermore, the fuel injection pressure and the injection rate can be increased higher than the conventional fuel injection device. As a result, in addition to being able to improve the combustion efficiency of the fuel more than the conventional fuel injection device, the fuel injection device 1C can suppress the influence of the pressure vibration in the first flow path F1 caused by the water hammer action from being transmitted into the combustion chamber CC.

[0117] As described above, the fuel injection devices 1B and 1C are fuel injection devices that inject fuel into the combustion chamber CC of the internal combustion engine EG, and include an injection port H that injects fuel into the combustion chamber CC, a high-pressure source 4 that supplies fuel at a predetermined pressure Pb and is connected to the injection port H, a first flow path F1 through which fuel is supplied from the high-pressure source 4, a first valve V1 provided in the first flow path F1 that opens and closes the injection port H, a second flow path F2 connected to the first flow path F1 and through which fuel is supplied from the first flow path F1, a second valve V2 provided in the second flow path F2 that opens and closes the second flow path F2, and a third valve V3 provided in the first flow path F1 that is located upstream of the first valve V1 in the first flow path F1 among the portions of the first flow path F1 and that opens and closes a portion of the first flow path F1 that is located downstream of the connection portion between the first flow path F1 and the second flow path F2. When the first valve V1 closes the injection port H and the third valve V3 closes the first flow path F1, a space S for holding fuel is formed in the first flow path F1. As a result, the fuel injection devices 1B and 1C can open the injection port H with the first valve V1 during a period when the pressure in the first flow path F1 is higher than the predetermined pressure Pb and inject fuel into the combustion chamber CC at a pressure higher than the predetermined pressure Pb. Consequently, the fuel injection devices 1B and 1C can further improve the combustion efficiency of the fuel.

[0118] <Modification Example 4 of the Embodiment> Hereinafter, Modification Example 4 of the embodiment will be described. In Modification Example 4 of the embodiment, the same reference numerals are given to the same components as in the embodiment, and the description thereof will be omitted. Hereinafter, as an example, a case where the internal combustion engine EG includes a plurality of different combustion chambers CC2 instead of the combustion chamber CC will be described.

[0119] FIG. 10 is a diagram showing an example of the configuration of a fuel injection system 10. The fuel injection system 10 includes a plurality of fuel injectors. Each of these plurality of fuel injectors injects fuel into one of a plurality of combustion chambers CC2. And, among these plurality of fuel injectors, some or all of the fuel injector 1, the fuel injector 1A, the fuel injector 1B, and the fuel injector 1C are included. Hereinafter, as an example, the case where the fuel injection system 10 includes four fuel injectors will be described. In this case, the internal combustion engine EG includes four combustion chambers CC2. And each of these four fuel injectors may be any of the fuel injector 1, the fuel injector 1A, the fuel injector 1B, and the fuel injector 1C. For this reason, in FIG. 10, as a sign indicating that each of the four fuel injectors 1 may be any of the fuel injector 1A, the fuel injector 1B, and the fuel injector 1C, each of the four fuel injectors 1 is given a sign of "1, 1A, 1B, 1C". Note that some of these four fuel injectors may be fuel injectors different from all of the fuel injector 1, the fuel injector 1A, the fuel injector 1B, and the fuel injector 1C.

[0120] Hereinafter, for convenience of explanation, each of the four combustion chambers CC2 will be described as combustion chamber CC2-1 to combustion chamber CC2-4. Further, hereinafter, for convenience of explanation, each of the four fuel injection devices included in the fuel injection system 10 will be described as the first fuel injection device 1D1 to the fourth fuel injection device 1D4. The first fuel injection device 1D1 is any one of the fuel injection device 1, the fuel injection device 1A, the fuel injection device 1B, and the fuel injection device 1C, and is a fuel injection device that injects fuel into the combustion chamber CC2-1. The second fuel injection device 1D2 is any one of the fuel injection device 1, the fuel injection device 1A, the fuel injection device 1B, and the fuel injection device 1C, and is a fuel injection device that injects fuel into the combustion chamber CC2-2. The third fuel injection device 1D3 is any one of the fuel injection device 1, the fuel injection device 1A, the fuel injection device 1B, and the fuel injection device 1C, and is a fuel injection device that injects fuel into the combustion chamber CC2-3. The fourth fuel injection device 1D4 is any one of the fuel injection device 1, the fuel injection device 1A, the fuel injection device 1B, and the fuel injection device 1C, and is a fuel injection device that injects fuel into the combustion chamber CC2-4. Further, hereinafter, for convenience of explanation, unless it is necessary to distinguish each of the first fuel injection device 1D1, the second fuel injection device 1D2, the third fuel injection device 1D3, and the fourth fuel injection device 1D4, they will be described as the fuel injection device 1D.

[0121] In the fuel injection system 10, the first flow path F1 of the four fuel injection devices 1D is connected to the zero-th flow path F0 connected to the high-pressure source 4. In the example shown in FIG. 10, each of the first flow paths F1 of the four fuel injection devices 1D is connected to the zero-th flow path F0 at one location. However, a part or all of the first flow paths F1 of the four fuel injection devices 1D may be configured to be connected to the zero-th flow path F0 at different portions.

[0122] In the fuel injection system 10, the second flow path F2 is not connected to each of the first flow paths F1 of the four fuel injection devices 1D, but is connected to the zeroeth flow path F0. That is, in the fuel injection system 10, one second flow path F2 is shared by each of the four fuel injection devices 1D. In the example shown in FIG. 10, the second flow path F2 is connected to the portion PP3, but may be configured to be connected to a portion other than the portion PP3 among the portions of the zeroeth flow path F0.

[0123] And in the fuel injection system 10 as well, a second valve V2 is provided in the second flow path F2. And in the fuel injection system 10 as well, the second valve V2 is driven by the drive unit A2.

[0124] Thus, the fuel injection system 10 is connected to four fuel injection devices 1D that inject fuel into the combustion chamber CC2 of the internal combustion engine EG, and a high-pressure source 4 that supplies fuel at a predetermined pressure Pb. The fuel injection system 10 includes a zeroeth flow path F0 from which fuel is supplied, a second flow path F2 connected to the zeroeth flow path F0 and from which fuel is supplied, and a second valve V2 provided in the second flow path F2 for opening and closing the second flow path F2.

[0125] Thereby, the fuel injection system 10 can instantaneously increase the pressure in the first flow path F1 to a pressure higher than the predetermined pressure Pb by the water hammer action generated by closing the zeroeth flow path F0 by the second valve V2. Therefore, the fuel injection system 10 can operate each of the four fuel injection devices 1D included in the fuel injection system 10 as described in each of the embodiment, Modification 1 to Modification 3 of the embodiment. As a result, the fuel injection system 10 can inject fuel into each of the four combustion chambers CC2 from each of the four fuel injection devices 1D at a pressure higher than the pressure of the high-pressure source 4 by opening and closing the zeroeth flow path F0 by the second valve V2. This is desirable because it leads to improving the fuel combustion efficiency of the internal combustion engine EG while reducing the number of parts of the internal combustion engine EG.

[0126] Here, FIG. 11 is a diagram showing an example of each of the timing of opening and closing of the second flow path F2, the timing of opening and closing of the injection ports H of each of the four fuel injection devices 1D, and the temporal change in the pressure in the four first flow paths F1 (i.e., the pressure in the portion PP3). Here, these four first flow paths F1 are the first flow paths F1 of each of the four fuel injection devices 1D. However, in FIG. 11, for simplicity of explanation, a case will be described in which each of the four fuel injection devices 1D performs only the main injection without performing injections such as pre-injection and pilot injection.

[0127] The horizontal axis of the graph shown in FIG. 11 indicates the elapsed time. Also, the vertical axis of the graph indicates the pressure in the first flow path F1 of each of the four fuel injection devices 1D, i.e., the pressure in the portion PP3. The curve F10 plotted in the graph shows an example of the temporal change in the pressure in the four first flow paths F1 when the four fuel injection devices 1D are controlled so that each of the four fuel injection devices 1D injects fuel into the four combustion chambers CC2 in order. Hereinafter, for convenience of explanation, such control of the four fuel injection devices 1D will be described by referring to it as the tenth control. Also, in the graph, a timing chart TC10 showing the timing of opening and closing of the second flow path F2, a timing chart TC11 showing the timing of opening and closing of the injection port H of the first fuel injection device 1D1, a timing chart TC12 showing the timing of opening and closing of the injection port H of the second fuel injection device 1D2, a timing chart TC13 showing the timing of opening and closing of the injection port H of the third fuel injection device 1D3, and a timing chart TC14 showing the timing of opening and closing of the injection port H of the fourth fuel injection device 1D4 are superimposed. Also, in FIG. 10, the period during which the piston of the internal combustion engine EG makes one rotation is indicated by an arrow labeled "one engine rotation".

[0128] In the example shown in FIG. 11, the fuel injection system 10 starts to open the second flow path F2 by the drive unit A2 at timing t11. As a result, as shown by the curve F10, in the fuel injection system 10, the pressure in the first flow path F1 of each of the four fuel injection devices 1D, that is, the pressure in the portion PP3, starts to decrease. This is because fuel starts to flow from the portion PP3 to the second flow path F2 at timing t11.

[0129] Thereafter, in the fuel injection system 10 controlled by the tenth control, the drive unit A2 starts to move the second valve V2 so that the second flow path F2 closes at timing t12 after a predetermined eleventh hour has elapsed from timing t11. As a result, in the fuel injection system 10, the pressure in the first flow path F1 of each of the four fuel injection devices 1D starts to increase at timing t12.

[0130] Then, in the fuel injection device 1 controlled by the tenth control, at a timing after timing t12, the pressure in the portion PP3 instantaneously becomes higher than a predetermined pressure Pb. This is a phenomenon that occurs because the fuel flowing out from the portion PP3 to the discharge port through the second flow path F2 is blocked by the second valve V2, and as a result, the pressure in the portion PP3 instantaneously becomes higher than the predetermined pressure Pb due to the water hammer effect generated. More specifically, the fuel flowing from the portion PP3 to the discharge port through the second flow path F2 is blocked by the second valve V2 in the second flow path F2 at timing t12. The blocked fuel is compressed according to the flow velocity of the fuel before being blocked. As a result, a water hammer effect occurs, and the pressure in the portion PP3 starts to rise.

[0131] However, as shown by curve F10, the pressure within portion PP3 decays and oscillates after timing t12. For this reason, the fuel injection system 10 controlled by the tenth control starts to open the injection port H of the first fuel injector 1D1 at timing t13. Timing t13 may be any timing within the period after timing t12 during which the pressure within portion PP3 rises from a pressure below a predetermined pressure Pb to a pressure exceeding the predetermined pressure Pb and then the pressure within portion PP3 starts to drop again. In the example shown in FIG. 11, timing t13 is the timing at which the pressure within portion PP3 returns from a pressure below the predetermined pressure Pb to the predetermined pressure Pb among the timings after timing t12.

[0132] The time difference between timing t12 and timing t13 is determined, for example, by trial and error through prior tests, experiments, etc. so that the combustion efficiency of the fuel approaches a desired combustion efficiency (e.g., the highest combustion efficiency, etc.), but it may also be determined based on theoretical calculations, may be determined by simulation, or may be determined by other methods. At timing t13 determined in this way, since the injection port H of the first fuel injector 1D1 starts to open, the fuel within portion PP3 starts to be injected into the combustion chamber CC2-1 from the injection port H by a pressure higher than the predetermined pressure Pb at timing t13.

[0133] After timing t13, in the fuel injection system 10 controlled by the tenth control, at timing t14 when a predetermined twelfth time has elapsed from timing t13, the drive unit A1 of the first fuel injector 1D1 starts to move the first valve V1 of the first fuel injector 1D1 so that the injection port H of the first fuel injector 1D1 closes. Then, at timing t14, in the fuel injection system 10, the first valve V1 closes the injection port H.

[0134] After timing t14, the fuel injection system 10 controlled by the tenth control waits with the injection port H of the first fuel injector 1D1 closed until starting the next injection of fuel by the first fuel injector 1D1. Further, in the fuel injection system 10, at timing t15 when a predetermined thirteenth hour has elapsed from timing t14, the drive unit A2 starts to open the second flow path F2 again. As a result, as shown by the curve F10, in the fuel injection system 10, the pressure in the first flow path F1 of each of the four fuel injectors 1D, that is, the pressure of the partial PP3 starts to decrease. Here, the thirteenth hour is determined so that the timing after the timing at which the vibration of the pressure in the partial PP3 from timing t2 due to the water hammer action has subsided becomes timing t15.

[0135] The fuel injection system 10 controlled by the 10th control causes such fuel injection to be repeatedly performed in a predetermined order for each of the four fuel injectors 1D. That is, each of the timings t15, t19, t23, t27, t31, and t35 indicates the timing at which the second flow path F2 starts to open in such repeated fuel injection. Also, each of the timings t16, t20, t24, t28, t32, and t36 indicates the timing at which the second flow path F2 closes in such repeated fuel injection. Also, the timing t17 indicates the timing at which the injection port H of the third fuel injector 1D3 starts to open in such repeated fuel injection. Also, the timing t18 indicates the timing at which the injection port H of the third fuel injector 1D3 closes in such repeated fuel injection. Also, the timing t21 indicates the timing at which the injection port H of the fourth fuel injector 1D4 starts to open in such repeated fuel injection. Also, the timing t22 indicates the timing at which the injection port H of the fourth fuel injector 1D4 closes in such repeated fuel injection. Also, the timing t25 indicates the timing at which the injection port H of the second fuel injector 1D2 starts to open in such repeated fuel injection. Also, the timing t26 indicates the timing at which the injection port H of the second fuel injector 1D2 closes in such repeated fuel injection. Also, the timing t29 indicates the timing at which the injection port H of the first fuel injector 1D1 starts to open again in such repeated fuel injection. Also, the timing t30 indicates the timing at which the injection port H of the first fuel injector 1D1 closes in such repeated fuel injection. Also, the timing t33 indicates the timing at which the injection port H of the third fuel injector 1D3 starts to open again in such repeated fuel injection. Also, the timing t34 indicates the timing at which the injection port H of the third fuel injector 1D3 closes in such repeated fuel injection. Also, the timing t37 indicates the timing at which the injection port H of the fourth fuel injector 1D4 starts to open again in such repeated fuel injection.Also, timing t38 indicates the timing when the injection port H of the fourth fuel injector 1D4 closes in such repeated fuel injection.

[0136] The fuel injection system 10 rotates the piston of the internal combustion engine EG by repeatedly causing such repeated fuel injection into each combustion chamber CC2 for each of the four fuel injectors 1D. Thereby, the fuel injection system 10 can perform fuel injection at a pressure higher than a predetermined pressure Pb for each fuel injection into each combustion chamber CC2. However, the fuel injection system 10 does not include a second valve V2 for each of the four fuel injectors 1D, but includes one common second valve V2, and this one second valve V2 causes a water hammer effect. For this reason, the fuel injection system 10 can improve the fuel combustion efficiency of the internal combustion engine EG while reducing the number of parts of the internal combustion engine EG. In other words, the fuel injection system 10 can suppress the manufacturing cost.

[0137] Note that the ECU3 described above opens and closes the first valve V1 to the third valve V3 according to the timing pre-stored in the storage unit 32. The user can cause the fuel injector 1 to open and close each of the first valve V1 to the third valve V3 at the timing desired by the user by storing in the storage unit 32 in advance the timing desired by the user. Here, the timing pre-stored in the storage unit 32 may be represented by time, may be represented by the elapsed time from a reference time, may be represented by other known methods, or may be represented by a method to be developed in the future.

[0138] As described above, the fuel injection device according to the embodiment (in the examples described above, the fuel injection devices 1 and 1A) is a fuel injection device that injects fuel into the combustion chamber (in the examples described above, inside the combustion chamber CC) of an internal combustion engine (in the examples described above, the internal combustion engine EG). The fuel injection device includes an injection port (in the examples described above, the injection port H) that injects fuel into the combustion chamber, a high-pressure source (in the examples described above, the high-pressure source 4) that supplies fuel at a predetermined pressure (in the examples described above, the predetermined pressure Pb), a first flow path (in the examples described above, the first flow path F1) that connects the high-pressure source and the injection port and through which fuel is supplied from the high-pressure source, a first valve (in the examples described above, the first valve V1) provided in the first flow path that opens and closes the injection port, a second flow path (in the examples described above, the second flow path F2) that is connected to the first flow path and through which fuel is supplied from the first flow path, and a second valve (in the examples described above, the second valve V2) provided in the second flow path that opens and closes the second flow path. Thereby, the fuel injection device can inject fuel at a pressure higher than the pressure of the high-pressure source.

[0139] Further, the fuel injection device may adopt a configuration that further includes a first drive unit (in the examples described above, the drive unit A1) that causes the first valve to open and close the injection port, a second drive unit (in the examples described above, the drive unit A2) that causes the second valve to open and close the second flow path, and a control unit (in the examples described above, the ECU 3, the control unit 36) that controls the first drive unit and the second drive unit.

[0140] Further, in the fuel injection device, the control unit controls the first drive unit and the second drive unit to perform a first injection process of injecting fuel from the injection port into the combustion chamber. The first injection process includes a first step of opening the second flow path by the second valve while the first valve closes the injection port, a second step of closing the second flow path by the second valve after a predetermined time has elapsed since the second valve opened the second flow path in the first step, and a third step of opening the injection port by the first valve at a timing after the timing when the second valve closed the second flow path in the second step. A configuration including these steps may be used.

[0141] Further, the fuel injection device is a fuel injection device that injects fuel into a combustion chamber of an internal combustion engine, and includes an injection port that injects fuel into the combustion chamber, a high-pressure source that supplies fuel at a predetermined pressure, and a first flow path that connects the high-pressure source and the injection port and through which fuel is supplied from the high-pressure source, a first valve provided in the first flow path that opens and closes the injection port, a second flow path connected to the first flow path and through which fuel is supplied from the first flow path, a second valve provided in the second flow path that opens and closes the second flow path, a third valve provided in the first flow path, which is a portion of the first flow path located upstream of the first valve in the first flow path and also a portion of the first flow path located downstream of the connection portion between the first flow path and the second flow path in the first flow path, and which opens and closes the first flow path (in the example described above, the third valve V3). When the first valve closes the injection port and the third valve closes the first flow path, a space (in the example described above, the space S) in which fuel is held is formed in the first flow path. Thereby, the fuel injection device can inject fuel at a pressure higher than the pressure of the high-pressure source.

[0142] Further, the fuel injection device may further include a first drive unit that causes the first valve to open and close the injection port, a second drive unit that causes the second valve to open and close the second flow path, a third drive unit that causes the third valve to open and close the first flow path (in the example described above, the drive unit A3), and a control unit that controls the first drive unit, the second drive unit, and the third drive unit (in the example described above, the ECU3, the control unit 36).

[0143] Further, in the fuel injection device, the control unit controls the first drive unit, the second drive unit, and the third drive unit, and performs a second injection process for injecting fuel from the injection port into the combustion chamber. The second injection process includes an 11th step of opening the second flow path by the second valve in a state where the third valve closes the first flow path, a 12th step of closing the second flow path by the second valve after a predetermined first time has elapsed since the second valve opened the second flow path in the 11th step, a 13th step of opening the first flow path by the third valve at a timing after the timing when the second valve closed the second flow path in the 12th step, a 14th step of closing the first flow path by the third valve after a predetermined second time has elapsed since the third valve opened the first flow path in the 13th step, and a 15th step of opening the injection port by the first valve between the timing when the third valve opened the first flow path in the 13th step and the timing when the third valve closed the first flow path in the 14th step. A configuration including these steps may be used.

[0144] Also, the fuel injection system according to the embodiment (in the example described above, the fuel injection system 10) includes a first fuel injection device (in the example described above, the fuel injection devices 1, 1A, 1B, 1C) that injects fuel into the combustion chamber of the internal combustion engine, a second fuel injection device (in the example described above, the fuel injection devices 1, 1A, 1B, 1C) that injects fuel into the combustion chamber, a high-pressure source that supplies fuel at a predetermined pressure, a first flow path (in the example described above, the first flow path F0) that is connected to the high-pressure source and through which fuel is supplied from the high-pressure source, a second flow path that is connected to the first flow path and through which fuel is supplied from the first flow path, and a second valve provided in the second flow path for opening and closing the second flow path. The first fuel injection device includes an eleventh injection port (in the example described above, the injection port H) that injects fuel into the combustion chamber, an eleventh flow path (in the example described above, the first flow path F1) that connects the first flow path and the eleventh injection port and through which fuel is supplied from the high-pressure source, and an eleventh valve (in the example described above, the first valve V1) provided in the eleventh flow path for opening and closing the eleventh injection port. The second fuel injection device includes a twenty-first injection port (in the example described above, the injection port H) that injects fuel into the combustion chamber, a twenty-first flow path (in the example described above, the first flow path F1) that connects the first flow path and the twenty-first injection port and through which fuel is supplied from the high-pressure source, and a twenty-first valve (in the example described above, the first valve V1) provided in the twenty-first flow path for opening and closing the twenty-first injection port. Thus, the fuel injection system can inject fuel at a pressure higher than the pressure of the high-pressure source 4.

[0145] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and may be changed, replaced, deleted, etc. without departing from the gist of the present invention.

[0146] Also, a program for realizing the function of any component in the device (e.g., ECU 3) described above may be recorded on a computer-readable recording medium, and the program may be read into a computer system and executed. Here, the "computer system" is assumed to include hardware such as an OS (Operating System) and peripheral devices. Also, the "computer-readable recording medium" refers to a flexible disk, a magneto-optical disk, a ROM, a portable medium such as a CD (Compact Disk)-ROM, and a storage device such as a hard disk built into a computer system. Furthermore, the "computer-readable recording medium" also includes a volatile memory (RAM) inside a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and holds the program for a certain period of time.

[0147] Also, the above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication wire) such as a telephone line. Also, the above program may be for realizing a part of the functions described above. Furthermore, the above program may be a so-called difference file (difference program) that can be realized in combination with a program already recorded in the computer system for the functions described above.

Explanation of Reference Numerals

[0148] 1, 1A, 1B, 1C... fuel injection device, 2... fuel injector, 4... high-pressure source, 10... fuel injection system, 32... memory unit, 33... first valve drive circuit, 34... second valve drive circuit, 35... third valve drive circuit, 36... control unit, A1, A2, A3... drive unit, CC... combustion chamber, EG... internal combustion engine, F0... first flow path, F1... second flow path, F2... third flow path, H... injection port, S... space, V1... first valve, V2... second valve, V3... third valve

Claims

1. A fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, an injection port for injecting the fuel into the combustion chamber, a first flow path connecting the high-pressure source for supplying the fuel at a predetermined pressure and the injection port, through which the fuel is supplied from the high-pressure source, a first valve provided in the first flow path for opening and closing the injection port, a first pipeline connected to the first flow path and through which the fuel is supplied from the first flow path, a first driving part provided in the first pipeline for driving the first valve by the pressure of the fuel supplied through the first pipeline, and causing the first valve to open and close the injection port, a second flow path connected to the first flow path and through which the fuel is supplied from the first flow path, a second valve provided in the second flow path for opening and closing the second flow path, comprising: the first driving part causes the first valve to open and close the injection port by electronic control independent of the electronic control of the opening and closing of the second valve, a fuel injection device.

2. a second driving part for causing the second valve to open and close the second flow path, a control part for controlling the first driving part and the second driving part, The fuel injection device according to claim 1, further comprising:

3. The control part controls the first driving part and the second driving part to perform a first injection process for injecting the fuel from the injection port into the combustion chamber. The first injection process includes: a first step of opening the second flow path by the second valve while the first valve closes the injection port; a second step of closing the second flow path by the second valve after a predetermined time has elapsed since the second valve opened the second flow path in the first step; A third step of opening the injection port by the first valve at a timing after the timing when the second valve closes the second flow path by the second step; is included, The fuel injection device according to claim 2.

4. A third valve provided at a portion of the first flow path that is located upstream of the first valve in the first flow path and downstream of the connection portion between the first flow path and the second flow path in the first flow path, and that opens and closes the first flow path; A second pipe connected to a portion of the first flow path that is located upstream of the third valve in the first flow path and downstream of the connection portion between the first flow path and the second flow path in the first flow path, and through which the fuel from the first flow path is supplied; A second drive unit that causes the second valve to open and close the second flow path; A third drive unit provided in the second pipe and driving the third valve by the pressure of the fuel supplied through the second pipe to cause the third valve to open and close the first flow path; comprising, The first pipe is connected to a portion of the first flow path that is located downstream of the third valve in the first flow path, In the first flow path, a space for holding the fuel is formed when the first valve closes the injection port and the third valve closes the first flow path. The fuel injection device according to claim 1.

5. A control unit that controls the first drive unit, the second drive unit, and the third drive unit; The fuel injection device according to claim 4, further comprising.

6. The control unit controls the first drive unit, the second drive unit, and the third drive unit to perform a second injection process of injecting the fuel from the injection port into the combustion chamber. In the second injection process, a 11th step of opening the second flow path by the second valve in a state where the third valve closes the first flow path; a 12th step of closing the second flow path by the second valve after a predetermined first time has elapsed since the second valve opened the second flow path in the 11th step; a 13th step of opening the first flow path by the third valve at a timing after the timing when the second valve closed the second flow path in the 12th step; a 14th step of closing the first flow path by the third valve after a predetermined second time has elapsed since the third valve opened the first flow path in the 13th step; a 15th step of opening the injection port by the first valve between the timing when the third valve opened the first flow path in the 13th step and the timing when the third valve closed the first flow path in the 14th step; are included, The fuel injection device according to claim 5.

7. A control method for a fuel injection device that injects fuel into a combustion chamber of an internal combustion engine, wherein the fuel injection device has an injection port for injecting the fuel into the combustion chamber, a first flow path that connects a high-pressure source that supplies the fuel at a predetermined pressure and the injection port and through which the fuel is supplied from the high-pressure source, a first valve provided in the first flow path for opening and closing the injection port, a first pipe line connected to the first flow path and through which the fuel is supplied from the first flow path, a first drive unit provided in the first pipe line for driving the first valve by the pressure of the fuel supplied through the first pipe line and causing the first valve to open and close the injection port, a second flow path connected to the first flow path and through which the fuel is supplied from the first flow path, a second valve provided in the second flow path for opening and closing the second flow path, a second drive unit for causing the second valve to open and close the second flow path, is provided with The control method is as follows A first step of opening the second flow path by the second valve in a state where the first valve closes the injection port; A second step of closing the second flow path by the second valve after a predetermined time has elapsed since the second valve opened the second flow path in the first step; A third step of opening the injection port by the first valve at a timing after the timing when the second valve closes the second flow path in the second step; and has Control method.

8. The fuel injection device A third valve provided in a portion of the first flow path that is located upstream of the first valve in the first flow path and downstream of the connection portion between the first flow path and the second flow path in the first flow path, for opening and closing the first flow path; A second pipe connected to a portion of the first flow path that is located upstream of the third valve in the first flow path and downstream of the connection portion between the first flow path and the second flow path in the first flow path, through which fuel from the first flow path is supplied; A third drive unit provided in the second pipe, for driving the third valve by the pressure of the fuel supplied through the second pipe and causing the third valve to open and close the first flow path; is provided with The first pipe is connected to a portion of the first flow path that is located downstream of the third valve in the first flow path; In the first flow path, a space for holding the fuel is formed when the first valve closes the injection port and the third valve closes the first flow path; The first step is a step of opening the second flow path by the second valve in a state where the first valve closes the injection port and the third valve closes the first flow path; The second step is a step of closing the second flow path by the second valve after a predetermined first time has elapsed since the second valve opened the second flow path in the first step. The third step includes: A fourth step of opening the first flow path by the third valve at a timing after the timing when the second valve closed the second flow path in the second step; A fifth step of closing the first flow path by the third valve after a predetermined second time has elapsed since the third valve opened the first flow path in the fourth step; A sixth step of opening the injection port by the first valve between the time when the third valve opened the first flow path in the fourth step and the time when the third valve closed the first flow path in the fifth step; are included. The control method according to claim 7.

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