JP7070327B2 - Fuel injection control device - Google Patents

Description

The present invention relates to a fuel injection control device.

Conventionally, the applicant has proposed a fuel injection device that injects fuel from the tip of a nozzle by controlling hydraulic pressure using two solenoid valves (see, for example, Patent Document 1). The injector described in Patent Document 1 is configured to be capable of injecting fuel from a nozzle at the tip by using an actuator using a piezo stack.

German Patent Application Publication No. 102013112751

When the fuel injection control device injects and controls the fuel, the fuel is injected and controlled from the common rail in which the fuel is stored to the internal combustion engine by using a plurality of fuel injection devices. When this fuel injection control device hydraulically controls fuel injection control using two solenoid valves (hereinafter referred to as the first valve and the second valve, respectively) in the fuel injection device (also referred to as an injector). , The first valve is driven to control the fuel injection timing, and the second valve is driven to control the fuel injection rate. The fuel injection rate can be changed by adjusting the opening speed of the nozzle needle at the tip of the fuel injection device.

Further, when a decompression request is made during normal control, the fuel injection control device can reduce the internal pressure of the common rail by opening the second valve of the fuel injection device. Further, even when the high-pressure fuel pump that supplies high-pressure fuel to the fuel injection device is stuck on the pumping side and fails, the hydraulic pressure in the hydraulic control chamber can be depressurized and a high-pressure abnormality can be prevented by opening the second valve. As a result, the fuel pressure can be adjusted to the target pressure even during normal control or when the high-pressure pump is stuck on the pumping side and fails.

For example, when the internal combustion engine has four cylinders, four fuel injection devices are provided in the internal combustion engine. When the above-mentioned two-valve configuration is adopted, two valves are provided for each of these four fuel injection devices, so that the fuel injection control device controls eight valves.

As described above, when there is a decompression request during normal times or abnormal times, the second valves for all cylinders are opened at the same time. However, if the fuel injection control device simultaneously opens and controls the second valves for all the cylinders, the energy supply load for driving the fuel injection control device becomes large and the heat stress becomes large, and there is a possibility that the fuel injection control device does not operate normally. This can be solved by increasing the stored energy so that the valves for all cylinders can be controlled to open at the same time, but it is necessary to increase the capacity value of the charging capacitor as the charging unit for storing energy. It is not preferable because the circuit size increases and the cost increases.

An object of the present invention is to provide a fuel injection control device capable of reducing the internal pressure of a common rail without applying heat stress to the charging unit as much as possible.

The invention according to claim 1 is a fuel injection control device for injecting and controlling the fuel from a common rail (5) in which fuel is stored to an internal combustion engine (11) by using a plurality of fuel injection devices (7 to 10). It is targeted. Each of the plurality of fuel injection devices includes a first solenoid (31), a first valve (29), a second solenoid (32), and a second valve (30). The first control unit (52) drives the first valve by energizing the first solenoid to control the fuel injection timing during normal injection control. During normal injection control, the second control unit (53) energizes the second solenoid with a peak current (Ip2) indicating the maximum set value using the charging voltage (Vboost2) charged in the charging unit (75). Then, by energizing a predetermined constant current (Ipb2) lower than the peak current without using the charging voltage, the second valve is driven to control the fuel injection rate.

When the internal pressure of the common rail is reduced during normal injection control or abnormal time, the first control unit closes the first valve and the second control unit controls at least one of the plurality of fuel injection devices. It is configured to open and control the second valve by energizing the second solenoid in the injection device.

When the internal pressure of the common rail is reduced during normal injection control or abnormal time, the second control unit sets the peak current energizing the second solenoid of the target fuel injection device lower than that during normal injection control. At the same time, control is performed by extending the time for energizing the pickup current by a predetermined time. According to the first aspect of the present invention, since the peak current is set lower than that during normal injection control, the internal pressure of the common rail can be reduced without applying thermal stress to the charged portion as much as possible.

The invention according to claim 5 is intended to be a fuel injection control device for injecting and controlling the fuel from a common rail in which fuel is stored to an internal combustion engine by using a plurality of fuel injection devices. Each of the plurality of fuel injection devices includes a first solenoid (31), a first valve (29), a second solenoid (32), and a second valve (30). The first control unit (52) drives the first valve (29) by applying a current to the first solenoid during normal injection control to control the fuel injection timing. The second control unit (53) injects a plurality of fuels by energizing a plurality of second solenoids by using a charging voltage (Vboost2) charged in the same charging unit (75) during normal injection control. The second valve (30) of the device (8, 9) is driven to change and control the fuel injection rate.

When the internal pressure of the common rail is reduced during normal injection control or abnormal time, the first control unit closes the first valve and the second control unit controls at least one of the plurality of fuel injection devices. It is configured to open and control the second valve by energizing the second solenoid in the injection device.

Then, in the period for reducing the internal pressure of the common rail, the second control unit sets the energization period of the second solenoid in the target fuel injection device to the energization period of the second solenoid during normal injection control in another fuel injection device. The period is different from that. According to the invention of claim 5, the energization period of the second solenoid in the target fuel injection device is different from the energization period of the second solenoid during normal injection control in other fuel injection devices. Even if a plurality of second solenoids are energized using the charging voltage of the same charging unit, the current load applied to the charging unit can be dispersed and the thermal stress can be reduced. As a result, the internal pressure of the common rail can be reduced without applying heat stress to the charged portion as much as possible.

Configuration diagram of the fuel injection control system in the first embodiment Sectional view schematically showing a fuel injection device Explanatory drawing explaining the flow of fuel when reducing the internal pressure of a common rail Block diagram showing electrical configuration Circuit diagram of booster circuit Circuit diagram of valve drive Circuit diagram of pump drive Part 1 of the explanatory diagram explaining the flow of injection control The figure which shows the change of the valve drive current which energizes the 1st and 2nd solenoids. A flowchart showing the processing when the internal pressure of the common rail is reduced and controlled. Part 2 of the explanatory diagram explaining the flow of injection control The figure which shows the change of the valve drive current at the time of a normal operation and an abnormality by comparison. Part 3 of the explanatory diagram explaining the flow of injection control Explanatory drawing explaining the flow of injection control in 2nd Embodiment A flowchart showing the processing when the internal pressure of the common rail is reduced and controlled. The figure which shows the change of the valve drive current at the time of a normal operation and an abnormality by comparison.

Hereinafter, some embodiments of the fuel injection control device will be described with reference to the drawings. In each embodiment, the same or similar reference numerals are given to the configurations that perform the same or similar operations, and the description thereof will be omitted as necessary.

(First Embodiment)
First, the configuration of the fuel injection control system 1 will be described with reference to FIG. The fuel injection control system 1 includes a feed pump 3, a high-pressure fuel pump 4, a common rail 5, a crank angle sensor 6, and fuel together with a fuel injection control device (hereinafter referred to as a control device) 2 by an ECU (Electronic (Engine) Control Unit). It mainly includes injection devices 7 to 10 and an internal combustion engine 11.

The control device 2 individually controls the fuel injection devices 7 to 10 to control the supply of fuel to the fuel chambers of the cylinders # 1 to # 4 of the internal combustion engine 11. In this embodiment, an example in which the internal combustion engine 11 has four cylinders is shown, but six cylinders may be used, and the present invention is not limited to this. Of the four cylinders, the two cylinders # 1 and # 4 will be referred to as the first bank, and the two cylinders # 2 and # 3 will be referred to as the second bank.

The feed pump 3 pumps the fuel stored in the fuel tank 12 to the high-pressure fuel pump 4. The high-pressure fuel pump 4 is, for example, a plunger type pump. The high-pressure fuel pump 4 is driven by the pump drive unit 60 (see below) of the control device 2 using the output shaft of the internal combustion engine 11. The high-pressure fuel pump 4 boosts the low-pressure fuel supplied from the feed pump 3 to high-pressure fuel and supplies it to the common rail 5 through the high-pressure fuel pipe 13. The common rail 5 is provided to supply fuel to the fuel injection devices 7 to 10. The common rail 5 temporarily stores the high-pressure fuel supplied from the high-pressure fuel pump 4 and distributes the high-pressure fuel to each of the fuel injection devices 7 to 10 through the high-pressure pipe 16 while maintaining the high pressure.

The common rail 5 is equipped with a pressure sensor 14. The pressure sensor 14 detects the fuel pressure accumulated in the common rail 5, and outputs this detection signal to the control device 2. The crank angle sensor 6 is configured by being combined with a signal rotor 15 and detects the rotation of a crankshaft (not shown) inside the internal combustion engine 11. The signal rotor 15 is configured in a disk shape, for example, and rotates integrally with the crankshaft of the internal combustion engine 11, for example. A large number of protrusions are configured on the outer peripheral portion of the signal rotor 15, and the crank angle sensor 6 outputs a crank angle signal according to the approach and separation of the protrusions of the signal rotor 15.

The control device 2 can calculate the engine speed in response to receiving the crank angle signal of the crank angle sensor 6. The control device 2 changes and controls the torque for rotating the crankshaft according to the change of the sensor signal S. The control device 2 injects and controls fuel through the fuel injection devices 7 to 10 based on various sensor signals S including a crank angle signal.

<Basic configuration and operation explanation of fuel injection devices 7 to 10>
Hereinafter, the basic configuration and operation of the fuel injection devices 7 to 10 will be described. The fuel injection devices 7 to 10 are provided for injecting fuel into the cylinder of the internal combustion engine 11, and are also referred to as an injector or a fuel injection valve.

Each fuel injection device 7 to 10 is provided with a built-in pressure sensor 7a to 10a, respectively. The fuel injection devices 7 to 10 have the same structure as each other. Therefore, in the following, the structure of the fuel injection device 7 will be described with reference to FIG. 2, and the structural description of the fuel injection devices 8 to 10 will be omitted.

As shown in FIG. 2, the fuel injection device 7 includes first to fourth members 21 to 24, a nozzle needle 25, a spring 26 for the nozzle needle 25, a hydraulic driven valve 27, a spring 28 for the hydraulic driven valve 27, and a first. It mainly includes one valve 29, a second valve 30, a first solenoid 31, a second solenoid 32, a first spring 33, a second spring 34, and the like.

The first member 21 includes a first high-pressure fuel flow path 35, a low-pressure chamber 36, and a low-pressure passage 37. When the first to third members 21 to 23 are assembled, the first high-pressure fuel flow path 35 is configured to penetrate through the first to third members 21 to 23. The first high-pressure fuel flow path 35 is connected to the common rail 5 through the high-pressure pipe 16, and high-pressure fuel is supplied from the common rail 5 through the high-pressure pipe 16.

The low pressure chamber 36 provided in the first member 21 is configured to communicate with the third passage 39 from the opening on the second member 22 side when the first valve 29 is opened, and when the first valve 29 is closed. It is configured to be cut off from the third passage 39. Further, the low pressure chamber 36 is configured to communicate with the second passage 41 from the opening on the second member 22 side when the second valve 30 is opened, and is between the low pressure chamber 36 and the second passage 41 when the second valve 30 is closed. Is configured to be blocked.

In the low pressure chamber 36, the periphery of the opening on the second member 22 side is sealed between the first member 21 and the second member 22. Further, the low pressure chamber 36 is configured so that the low pressure passage 37 communicates with the low pressure chamber 36. The low pressure pipe 38 shown in FIG. 1 is connected to the low pressure passage 37. The low-pressure fuel inside the low-pressure chamber 36 is configured to flow out of the low-pressure chamber 36 and be returned to the fuel tank 12 via the low-pressure passage 37 and the low-pressure pipe 38.

A first valve 29, a second valve 30, a first solenoid 31, a second solenoid 32, a first spring 33, and a second spring 34 are arranged inside the low pressure chamber 36 of the first member 21.

Normally, the first spring 33 is arranged so as to urge the first valve 29 toward the third passage 39. In this case, since the first valve 29 is closed, the space between the low pressure chamber 36 and the third passage 39 is cut off. The second spring 34 is arranged so as to urge the second valve 30 toward the second passage 41. In this case, since the second valve 30 is closed, the space between the low pressure chamber 36 and the second passage 41 is cut off.

When the first solenoid 31 is energized, it generates an electromagnetic force and repels the urging force of the first spring 33 to separate the first valve 29 from the second member 22. As a result, the first valve 29 can be opened and driven by energizing the first solenoid 31, and the low pressure chamber 36 and the third passage 39 can communicate with each other by opening the first valve 29.

When the second solenoid 32 is energized, it generates an electromagnetic force and repels the urging force of the second spring 34 to separate the second valve 30 from the second member 22. As a result, the second valve 30 can be opened and driven by energizing the second solenoid 32, and the low pressure chamber 36 and the second passage 41 can be communicated with each other by opening the second valve 30.

The second member 22 includes a third passage 39, an intermediate chamber 40, and a second passage 41, and further comprises a second high-pressure fuel flow path 35a branched from the first high-pressure fuel flow path 35. .. The high-pressure fuel is branched and supplied from the first high-pressure fuel flow path 35 to the second high-pressure fuel flow path 35a. The second high-pressure fuel flow path 35a includes a third orifice 35aa and is connected to the annular chamber 42. The third orifice 35aa limits the flow rate of the high pressure fuel flowing through the second high pressure fuel flow path 35a. The structure of the second high-pressure fuel flow path 35a itself is the third because the second high-pressure fuel flow path 35a is provided with a plurality of third orifices 35a or the flow path area of the second high-pressure fuel flow path 35a is small. It may be configured as an orifice 35aa.

The second passage 41 includes a second orifice 41a, and connects the low pressure chamber 36 and the first control chamber 43 without passing through the inside of the hydraulic driven valve 27. Even if the second passage 41 is provided with a plurality of second orifices 41a or the flow path area of the second passage 41 is made small so that the structure of the second passage 41 itself is configured as the second orifice 41a. good.

The annular chamber 42 is configured to be annular and is configured to communicate with the first control chamber 43 through the opening on the third member 23 side. The first control chamber 43 is configured in the third member 23. The first control chamber 43 is arranged in contact with the second member 22, and is provided with a partial opening on the side of the second member 22. The periphery of this opening is sealed between the second member 22 and the third member 23. A connection passage 44 is connected to the first control room 43. The connection passage 44 connects the passage between the first control chamber 43 and the second control chamber 49. The connecting passage 44 includes a fourth orifice 44a, and the fourth orifice 44a limits the flow rate of fuel flowing through the connecting passage 44. The connection passage 44 may be provided with a plurality of fourth orifices 44a, and the structure of the connection passage 44 itself has the function of the fourth orifice 44a by setting the flow path area of the connection passage 44 to be small. You may have.

A hydraulic driven valve 27 is arranged inside the first control chamber 43. The hydraulic driven valve 27 is formed in a columnar shape. The columnar hydraulic driven valve 27 is configured such that the first passage 45 penetrates in the direction of the central axis. The first passage 45 includes a first orifice 45a. The first orifice 45a limits the flow rate of fuel flowing through the first passage 45. The first passage 45 may include a plurality of first orifices 45a, or the first passage 45 may have the function of the first orifice 45a by setting the flow path area of the first passage 45 to be small. ..

Inside the first control chamber 43, a spring 28 for urging the hydraulic driven valve 27 in a direction approaching the second member 22 is arranged. When the hydraulic driven valve 27 is in contact with the second member 22, the intermediate chamber 40 communicates with the first control chamber 43 via the first passage 45 and the first orifice 45a, but the third member of the annular chamber 42. The opening on the side of 23 is closed by the hydraulic driven valve 27.

For example, as shown in FIG. 3, when the hydraulic driven valve 27 is separated from the second member 22, the intermediate chamber 40 communicates with the first control chamber 43 without passing through the first passage 45, and the annular chamber 42 also communicates with the first control chamber 43. It communicates with the first control room 43. Further, as shown in FIGS. 2 and 3, the second passage 41 is configured to communicate with the first control chamber 43 without passing through the hydraulic driven valve 27. The second passage 41 directly communicates the low pressure chamber 36 with the first control chamber 43 regardless of the position of the hydraulic driven valve 27, that is, the lift state of the hydraulic driven valve 27.

As shown in FIG. 2, the fourth member 24 includes a high pressure chamber 46, an injection hole 47, a cylinder 48, and a second control chamber 49. The high-pressure fuel is supplied to the high-pressure chamber 46 through the first high-pressure fuel flow path 35. A nozzle needle 25 is arranged inside the fourth member 24. The tip of the nozzle needle 25 is formed in a conical shape and the base end is formed in a cylindrical shape, and the high pressure chamber 46 is arranged so as to cover the side surface thereof. The cylinder 48 supports the nozzle needle 25 so as to be slidable back and forth in the vertical direction of FIG. A second control chamber 49 is arranged on the back of the nozzle needle 25. The second control room 49 is connected to the first control room 43 through the connection passage 44.

Inside the second control chamber 49, a spring 26 for urging the nozzle needle 25 in the direction of pressing the nozzle needle 25 against the injection hole 47 is arranged. The control room is composed of the first control room 43 and the second control room 49. The injection hole 47 is configured to communicate with the inside of the cylinder of the internal combustion engine 11.

When the pressure inside the second control chamber 49 is higher than a predetermined pressure, the nozzle needle 25 keeps the high pressure chamber 46 and the injection hole 47 shut off, or the nozzle needle 25 closes the injection hole 47. Moving. On the contrary, when the pressure of the second control chamber 49 is equal to or lower than the predetermined pressure, the nozzle needle 25 moves to the side of the third member 23, that is, in the upward direction in the drawing. In this case, the high-pressure fuel is injected from the inside of the high-pressure chamber 46 through the injection hole 47. Therefore, based on the pressure inside the first control chamber 43 and the second control chamber 49, the high pressure chamber 46 and the inside of the cylinder of the internal combustion engine 11 can communicate with each other and shut off.

<Explanation of pressure changes in each chamber inside the fuel injection devices 7 to 10>
The fuel injection control system 1 operates by setting various modes, and the control device 2 controls fuel injection from the injection holes 47 of each fuel injection device 7 to 10 based on this mode, or fuels. The internal pressure of the common rail 5 can be reduced by controlling the discharge of fuel to the fuel tank 12 through the injection devices 7 to 10. Hereinafter, the pressure change in each chamber inside the fuel injection devices 7 to 10 due to the opening / closing operation of the first valve 29 and the second valve 30 in each mode will be described.

First, it is assumed that the urging force of the first spring 33 and the urging force of the second spring 34 act to close both the first valve 29 and the second valve 30. When the first valve 29 is closed, the space between the third passage 39 and the low pressure chamber 36 is cut off. Further, when the second valve 30 is closed, the space between the second passage 41 and the low pressure chamber 36 is cut off. In such an initial state, the insides of the second control chamber 49, the first control chamber 43, the intermediate chamber 40, the third passage 39, and the second passage 41 are sealed, and the fuel pressure inside these is in a high pressure state. Balance with. Therefore, the injection hole 47 is closed. Further, the hydraulic driven valve 27 comes into contact with the second member 22 by being urged by the spring 28.

<Low injection rate mode>
Hereinafter, changes in the pressure state of each chamber inside the fuel injection devices 7 to 10 in the low injection rate mode in which fuel is injected from the injection holes 47 into the internal combustion engine 11 relatively slowly will be described. In this low injection rate mode, the control device 2 opens the first valve 29 with the second valve 30 closed from the initial state, and then closes the first valve 29.

When the first valve 29 opens, the third passage 39 and the low pressure chamber 36 communicate with each other. The low pressure chamber 36, the intermediate chamber 40, and the first control chamber 43 communicate with each other through the third passage 39. As a result, the pressure of the first control chamber 43 and the intermediate chamber 40 is reduced, and the pressure of the intermediate chamber 40 is reduced to the same level as that of the low pressure chamber 36.

Further, although the fuel accumulated inside the first control chamber 43 flows to the side of the intermediate chamber 40 through the first passage 45, the flow rate of the fuel through the first orifice 45a is limited by the action of the first orifice 45a. Will be done. At this time, the first passage 45 creates a pressure difference before and after the first orifice 45a. As a result, the first control chamber 43 is held in the medium pressure state.

Due to the action of the fuel pressure inside the first control chamber 43, the hydraulic driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22. Since the opening on the third member 23 side of the annular chamber 42 is closed by the hydraulic driven valve 27, the shutoff state between the second high-pressure fuel flow path 35a and the first control chamber 43 is maintained.

Since the pressure in the first control chamber 43 is in the medium pressure state, the pressure in the second control chamber 49 is also changed to the medium pressure state. Then, the high-pressure fuel acts on the nozzle needle 25 through the first high-pressure fuel flow path 35, and slides the nozzle needle 25 toward the second control chamber 49 along the cylinder 48. As a result, the nozzle needle 25 is opened and high-pressure fuel is injected from the injection hole 47. At this time, since the fuel flow path through the first orifice 45a is relatively narrowly restricted, the speed at which the first control chamber 43 reaches the medium pressure state also slows down. As a result, the valve opening speed of the nozzle needle 25 becomes relatively slow, and the change in the fuel injection amount with the passage of time, that is, the injection rate is relatively low.

After that, when the first valve 29 is closed, the third passage 39, the intermediate chamber 40, the second passage 41 and the first control chamber 43 are sealed, but the fuel in the first control chamber 43 is the first orifice 45a. It also flows into the intermediate chamber 40 and the third passage 39 through the passage. On the other hand, since a pressure difference is generated between the annular chamber 42 and the first control chamber 43, the hydraulic driven valve 27 is provided so that the fuel in the second high-pressure fuel flow path 35a repels the urging force of the spring 28 through the annular chamber 42. Press.

As a result, the lift amount of the hydraulic driven valve 27 is reduced, and the high-pressure fuel flows into the first control chamber 43 and the second control chamber 49 through the annular chamber 42, and as a result, the first control chamber 43 and the second control chamber 49 are moved. Increase the pressure. When the internal pressure of the first control chamber 43 and the second control chamber 49 changes to a high pressure state equal to the pressure of the first high-pressure fuel flow path 35, the urging force of the spring 28 acts and the hydraulic driven valve 27 becomes the second member. It abuts on the side of 22. As a result, the hydraulic driven valve 27 shuts off between the annular chamber 42 and the first control chamber 43, and returns to the above-mentioned initial state.

<High injection rate mode>
Hereinafter, changes in the pressure state of each chamber inside the fuel injection device 7 in the high injection rate mode when fuel is injected at high speed from the injection holes 47 will be described. In this high injection rate mode, the control device 2 controls the first valve 29 and the second valve 30 to open at substantially the same time from the initial state.

When the first valve 29 and the second valve 30 open almost at the same time, the third passage 39 and the low pressure chamber 36 communicate with each other, and the second passage 41 and the low pressure chamber 36 also communicate with each other. Therefore, the low pressure chamber 36, the intermediate chamber 40, and the first control chamber 43 communicate with each other through the third passage 39 and the second passage 41. As a result, the pressure of the first control chamber 43 and the intermediate chamber 40 is reduced.

At this time, the pressure of the intermediate chamber 40 is reduced to the same level as that of the low pressure chamber 36, but the pressure can be reduced more quickly than when only the first valve 29 described above is opened. Further, although the fuel accumulated in the first control chamber 43 flows to the side of the intermediate chamber 40 through the first passage 45, the flow rate of the fuel is limited because the first orifice 45a acts. At this time, the first passage 45 creates a pressure difference before and after the first orifice 45a.

On the other hand, the fuel inside the first control chamber 43 flows to the low pressure chamber 36 via the second passage 41. At this time, the second orifice 41a acts and the flow rate of the fuel through the second orifice 41a is also limited. The second passage 41 creates a pressure difference before and after the second orifice 41a. As a result, the first control chamber 43 is held in the medium pressure state.

At this time, the hydraulic pressure driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22 by the action of the fuel pressure inside the first control chamber 43. Since the opening on the side of the third member 23 of the annular chamber 42 is closed by the hydraulic driven valve 27, the shutoff state between the second high-pressure fuel flow path 35a and the first control chamber 43 is maintained.

When the first control chamber 43 is in the medium pressure state, the pressure in the second control chamber 49 is also changed to the medium pressure state. Since the first control chamber 43 and the second control chamber 49 are in the medium pressure state, when the high pressure fuel acts on the nozzle needle 25 through the first high pressure fuel flow path 35 as described above, the nozzle needle 25 is along the cylinder 48. And slides to the side of the second control chamber 49. As a result, the nozzle needle 25 is opened and high-pressure fuel is injected from the injection hole 47. At this time, since the fuel flow path through the first orifice 45a and the second orifice 41a is widely restricted as compared with the above-mentioned low injection rate mode, the speed at which the first control chamber 43 reaches the medium pressure state is also high. Become. As a result, the valve opening speed of the nozzle needle 25 becomes relatively high, and the change in the fuel injection amount with the passage of time, that is, the injection rate becomes relatively high.

After that, even if the second valve 30 is closed, there is almost no change in the internal hydraulic pressure of each chamber such as the first control chamber 43, but after that, when the first valve 29 is closed, the internal fuel of the first control chamber 43 is fueled. Flows into the intermediate chamber 40 and the third passage 39 through the first orifice 45a. At this time, the third passage 39, the intermediate chamber 40, the second passage 41 and the first control chamber 43 are sealed, and the intermediate chamber 40 and the first control chamber 43 are in a medium pressure state.

Since a pressure difference is generated between the annular chamber 42 and the first control chamber 43, the hydraulic driven valve 27 is pressed so that the fuel in the second high-pressure fuel flow path 35a repels the urging force of the spring 28 through the annular chamber 42. As a result, the lift amount of the hydraulic driven valve 27 is reduced, and the high-pressure fuel flows into the first control chamber 43 and the second control chamber 49 through the annular chamber 42, and as a result, the first control chamber 43 and the second control chamber 49 are moved. Increase the pressure. When the internal pressure of the first control chamber 43 and the second control chamber 49 changes to a high pressure state equal to the pressure of the first high-pressure fuel flow path 35, the urging force of the spring 28 acts and the hydraulic driven valve 27 becomes the second member. It abuts on the side of 22. As a result, the hydraulic driven valve 27 shuts off between the annular chamber 42 and the first control chamber 43, and returns to the above-mentioned initial state.

<Explanation of the difference in lift speed of the nozzle needle 25 based on the open / closed state of the second valve 30>
When the first valve 29 and the second valve 30 are opened substantially at the same time, the internal pressure of the first control chamber 43 drops more quickly than when only the first valve 29 opens. Therefore, when the first valve 29 and the second valve 30 are opened substantially at the same time, the lift speed of the nozzle needle 25 is faster than when only the first valve 29 is opened. Therefore, when the first valve 29 and the second valve 30 are opened at the same time, the injection rate can be increased as compared with the case where only the first valve 29 is opened.

<Boot injection mode>
Hereinafter, the pressure change in each chamber of the fuel injection device 7 in the boot injection mode will be described. In the boot injection mode, the fuel injection devices 7 to 10 gradually increase the injection rate to inject fuel from the injection holes 47. In the boot injection mode, the control device 2 controls to open the second valve 30 after opening the first valve 29 from the above-mentioned initial state.

First, when the first valve 29 opens, the third passage 39 and the low pressure chamber 36 communicate with each other. Therefore, the low pressure chamber 36, the intermediate chamber 40, and the first control chamber 43 communicate with each other through the third passage 39. As a result, the pressure of the first control chamber 43 and the intermediate chamber 40 is reduced. At this time, the pressure of the intermediate chamber 40 is reduced to the same level as that of the low pressure chamber 36. Further, although the fuel accumulated in the first control chamber 43 flows to the side of the intermediate chamber 40 through the first passage 45, the first orifice 45a acts, so that the flow rate of the fuel through the first orifice 45a is limited. .. At this time, the first passage 45 creates a pressure difference before and after the first orifice 45a, and the first control chamber 43 is held in the medium pressure state. The hydraulic pressure driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22 by the action of the fuel pressure inside the first control chamber 43. Since the opening on the side of the third member 23 of the annular chamber 42 is closed by the hydraulic driven valve 27, the shutoff state between the second high-pressure fuel flow path 35a and the first control chamber 43 is maintained.

Then, similarly to the above, the high-pressure fuel acts on the nozzle needle 25 through the first high-pressure fuel flow path 35, and the nozzle needle 25 is slid along the cylinder 48 toward the second control chamber 49. As a result, the injection hole 47 is opened, and the high-pressure fuel is injected from the injection hole 47. At this time, since the fuel flow path through the first orifice 45a is relatively narrowly restricted, the speed at which the pressure of the first control chamber 43 is reduced is also slowed down. As a result, the valve opening speed of the nozzle needle 25 becomes relatively slow, and in the initial period of the boot injection mode, the change in the fuel injection amount with respect to the passage of time, that is, the injection rate becomes relatively low. After that, when the second valve 30 is opened, the fuel in the first control chamber 43 flows to the low pressure chamber 36 via the second passage 41. At this time, the second orifice 41a acts to limit the flow rate of fuel through the second orifice 41a. At this time, the second passage 41 creates a pressure difference before and after the second orifice 41a.

Since the fuel flow path through the first orifice 45a and the second orifice 41a is wider than that in the initial period of the boot injection mode, the speed at which the first control chamber 43 is lowered and reaches the medium pressure state is also increased. As a result, the valve opening speed of the nozzle needle 25 becomes relatively high, and the change in the fuel injection amount with the passage of time, that is, the injection rate becomes relatively large.

After that, even if the second valve 30 is closed, there is almost no change in the internal hydraulic pressure of each chamber such as the first control chamber 43, but after that, when the first valve 29 is closed, the internal fuel of the first control chamber 43 is fueled. Flows into the intermediate chamber 40 and the third passage 39 through the first orifice 45a. Then, the third passage 39, the intermediate chamber 40, the second passage 41, and the first control chamber 43 are sealed, and the intermediate chamber 40 and the first control chamber 43 are in a medium pressure state.

Since a pressure difference is generated between the annular chamber 42 and the first control chamber 43, the hydraulic driven valve 27 is pressed so that the fuel in the second high-pressure fuel flow path 35a repels the urging force of the spring 28 through the annular chamber 42. As a result, the lift amount of the hydraulic driven valve 27 is reduced, and the high-pressure fuel flows into the first control chamber 43 and the second control chamber 49 through the annular chamber 42, and as a result, the first control chamber 43 and the second control chamber 49 are moved. Increase the pressure. When the internal pressure of the first control chamber 43 and the second control chamber 49 changes to a high pressure state equal to the pressure of the first high-pressure fuel flow path 35, the urging force of the spring 28 acts and the hydraulic driven valve 27 becomes the second member. It abuts on the side of 22. As a result, the hydraulic driven valve 27 shuts off between the annular chamber 42 and the first control chamber 43, and returns to the above-mentioned initial state.

<Rail decompression mode, full decompression mode>
Hereinafter, the rail decompression mode and the full decompression mode will be described with reference to FIG. In order to reduce the internal pressure of the common rail 5, a rail decompression mode and a full decompression mode are provided. In this rail depressurization mode, the control device 2 controls the opening of the second valve 30 by the second solenoid 32 while the first valve 29 is closed and controlled by the first solenoid 31 from the initial state and held in the closed state.

As described above, in the initial state, the hydraulic driven valve 27 is urged by the spring 28, and the hydraulic driven valve 27 is in contact with the second member 22. When the second valve 30 is opened in this state, the stored fuel in the first control chamber 43 is discharged to the low pressure chamber 36 through the second passage 41, and the internal pressure of the first control chamber 43 becomes low.

The stored fuel in the second high-pressure fuel flow path 35a presses the hydraulically driven valve 27 through the annular chamber 42, and the hydraulically driven valve 27 is separated from the second member 22 to reduce the lift amount. Then, the first control room 43 and the intermediate room 40 communicate with each other. Since the pressure in the intermediate chamber 40 becomes the same level as the pressure in the first control chamber 43, the hydraulic driven valve 27 receives the fuel pressure from the second high-pressure fuel flow path 35a and is not attracted to the intermediate chamber 40. Therefore, the fuel flows from the common rail 5 into the low pressure chamber 36 through the first high pressure fuel flow path 35, the second high pressure fuel flow path 35a, the first control chamber 43, and the second passage 41, and the fuel flows from the low pressure chamber 36 through the low pressure pipe 38. It is discharged to the tank 12. See the fuel flow indicated by the arrow in Figure 3.

Further, the fuel flow rate flowing into the first control chamber 43 through the third orifice 35aa of the second high-pressure fuel flow path 35a is larger than the fuel flow rate flowing into the low-pressure chamber 36 through the second orifice 41a of the second passage 41. Is set to. Therefore, the amount of fuel flowing into the first control chamber 43 from the second high-pressure fuel flow path 35a is larger than the amount of fuel discharged from the first control chamber 43.

As a result, the fuel pressure in the first control chamber 43 and the second control chamber 49 does not decrease, and the nozzle needle 25 does not slide along the cylinder 48. As a result, the high-pressure chamber 46 and the injection hole 47 can be maintained in a state of being blocked by the nozzle needle 25. As a result, the fuel can be discharged from the low pressure chamber 36 without injecting the fuel into the internal combustion engine 11 from the injection holes 47, and the internal pressure of the common rail 5 can be reduced.

As described above, in the rail depressurization mode, the internal pressure of the common rail 5 can be reduced by using at least one fuel injection device (for example, 7). Further, a mode in which the processing operation of the rail depressurization mode is executed by using all the fuel injection devices 7 to 10 is referred to as a full decompression mode. In this full decompression mode, all fuel injection devices 7-10 can be used to quickly reduce the internal pressure of the common rail 5.

<Explanation of electrical configuration of control device 2>
Next, the drive system circuit of the fuel injection devices 7 to 10 will be described. FIG. 4 schematically shows the electrical configuration of the control device 2.
The control device 2 operates by supplying power to the power supply voltage VB from the battery. Here, a specific example in which the power supply voltage VB is a 12V system is shown, but it may be a 24V system and can be changed as appropriate. The control device 2 includes a microcomputer (hereinafter referred to as a microcomputer) 51, a first control IC 52, a second control IC 53, a first booster circuit 54, a second booster circuit 55, a first valve drive unit 56, 57, and a second valve. It includes drive units 58 and 59, and a pump drive unit 60. The first control IC 52 corresponds to the first control unit, and the second control IC 53 corresponds to the second control unit.

The first valve drive unit 56 is provided for driving the first valve 29 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank, and the first valve drive unit 57 is the second bank. It is provided for driving the first valve 29 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3. The second valve drive unit 58 is provided for driving the second valve 30 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank, and the second valve drive unit 59 is provided in the second bank. It is provided for driving the second valve 30 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3.

The microcomputer 51 is composed of, for example, an internal memory (none of which is shown) by a CPU, RAM, and ROM, and proactively executes various controls by executing a program stored in the internal memory. The microcomputer 51 outputs an injection signal according to an injection start command and an injection stop command to the first control IC 52 and the second control IC 53.

Further, the microcomputer 51 can communicate with the first control IC 52 and the second control IC 53, respectively, using the serial communication line. The microcomputer 51 can change various setting values set in the memories of the first control IC 52 and the second control IC 53, whereby the microcomputer 51 controls the first control IC 52 and the second control IC 53 in an integrated manner. There is. This set value includes the peak currents Ip and Ip2, the pickup currents Ipa and Ipa2, the constant currents Ipb and Ipb2, and their energization continuation periods, which will be described in detail later. Further, the microcomputer 51 outputs a pump control signal to the first control IC 52 using a dedicated line. This pump control signal indicates a control signal for controlling the high pressure fuel pump 4.

The first control IC 52 and the second control IC 53 are, for example, integrated circuit devices by ASIC, each of which includes a control main body such as a logic circuit and a CPU, and memories such as RAM, ROM, and EEPROM, and are based on hardware and software. It is configured to execute various controls.

The first control IC 52 drives and controls the first booster circuit 54, the first valve drive units 56 and 57, and the pump drive unit 60. The first booster circuit 54 boosts the power supply voltage VB based on the booster control signal input from the first control IC 52, and supplies the first booster voltage Vboost1, which is higher than the power supply voltage VB, to the first valve drive units 56, 57 and the pump. It is supplied to the drive unit 60.

FIG. 5 shows a configuration example of the first booster circuit 54. A coil 71, a drain source of the n-channel type MOSFET 72, and a resistor 73 are connected in series between the supply terminal of the power supply voltage VB and the ground. A diode 74 is forwardly connected from the common connection point of the drain of the coil 71 and the MOSFET 72 to the output node of the first boost voltage Vboost 1, and the charging capacitor 75 is connected between this output node and the source of the MOSFET 72. Therefore, when the first control IC 52 controls the MOSFET 72 on and off, the energy stored in the coil 71 can be gradually stored in the charging capacitor 75 while passing a current through the coil 71. As a result, the charging capacitor 75 can charge the first boost voltage Vboost1, which is higher than the power supply voltage VB.

FIG. 6 shows the circuit configuration of the first valve drive unit 56. The first valve drive unit 56 is connected to the output terminals 2a to 2c of the control device 2 when driving the first valve 29 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank. The power is cut off from the first solenoid 31. As a result, the first control IC 52 controls the fuel injection timing by applying a current to the first solenoid 31 using the first valve drive unit 56.

The first valve drive unit 56 is mainly composed of a discharge switch 81, a constant current switch 82, and selection switches 83, 84, and is further configured by combining current detection resistors 85, 86 and diodes 87 to 90. The discharge switch 81 and the selection switches 83 and 84 are each composed of, for example, an n-channel type MOS transistor. The constant current switch 82 is composed of, for example, an n-channel type MOS transistor.

The first boost voltage Vboost1 charged in the charging capacitor 75 of the first booster circuit 54 is input to the drain of the MOS transistor which is the input terminal of the discharge switch 81. In this discharge switch 81, the first boost voltage Vboost1 input to the input terminal according to the control signal given from the first control IC 52 to the control terminal of the discharge switch 81 is transmitted from the output terminal side to the positive output terminal 2a of the control device 2. It can be energized.

Between the input node of the power supply voltage VB and the positive output terminal 2a of the control device 2, the drain source of the MOS transistor constituting the constant current switch 82 and the anode and cathode of the diode 87 are connected in series. Further, the diode 88 is connected in the opposite direction between the positive output terminal 2a of the control device 2 and the ground. The diodes 87 and 88 are provided to prevent energization from the positive output terminal 2a to the supply terminal side of the power supply voltage VB and from the positive output terminal 2a to the ground side, respectively.

A first solenoid 31 for driving the first valve 29 of the fuel injection device 7 is connected between the positive output terminal 2a and the first negative output terminal 2b of the control device 2. The first solenoid 31 opens the first valve 29 of the fuel injection device 7 when the power is turned on. When the first solenoid 31 is energized and turned off, the first valve 29 is closed by the urging force of the first spring 33.

A diode 89 is forwardly connected between the first negative output terminal 2b of the control device 2 and the output node of the first boost voltage Vboost1 of the first booster circuit 54. The diode 89 is provided to feed back the stored energy based on the current flowing through the first solenoid 31 to the charging capacitor 75 of the first booster circuit 54 when the injection command is turned off.

A first solenoid 31 for driving the first valve 29 of the fuel injection device 10 is connected between the positive output terminal 2a and the second negative output terminal 2c of the control device 2. The first solenoid 31 opens the first valve 29 of the fuel injection device 10 when the power is turned on, and closes the first valve 29 when the power is turned off.

A diode 90 is forwardly connected between the second negative output terminal 2c of the control device 2 and the output node of the first boost voltage Vboost1 of the first booster circuit 54. When the first control IC 52 receives an injection stop command as an injection signal from the microcomputer 51, the diode 90 transfers the stored energy based on the current flowing through the first solenoid 31 to the charging capacitor 75 of the first booster circuit 54. It is provided for feedback charging.

Between the first negative output terminal 2b of the control device 2 and the ground, the drain source of the MOS transistor constituting the selection switch 83 and the current detection resistor 85 are connected in series. Between the second negative output terminal 2c of the control device 2 and the ground, the drain source of the MOS transistor constituting the selection switch 84 and the current detection resistor 86 are connected in series.

The selection switches 83 and 84 are provided to select the fuel injection devices 7 and 10 for injecting fuel. The current detection resistor 85 detects the voltage flowing through the first solenoid 31 of the fuel injection device 7 while the selection switch 83 is turned on. This detected value is input to the first control IC 52. The current detection resistor 86 detects the voltage flowing through the first solenoid 31 of the fuel injection device 10 while the selection switch 84 is turned on. This detected value is input to the first control IC 52.

The first control IC 52 controls on / off of the discharge switch 81, the constant current switch 82, and the selection switches 83, 84 based on the set value set by the microcomputer 51, the injection signal, and the detection current of the current detection resistor 85. .. Since the first valve drive unit 56 is configured in this way, the first control IC 52 can pass a current through the first solenoid 31 using the first valve drive unit 56 and control the power interruption, and each fuel injection device 7 can be controlled. The opening and closing of the first valve 29 of 10 can be controlled.

The first valve drive unit 57 is connected to the output terminals 2a to 2c of the control device 2 when driving the first valve 29 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank. The power is cut off from the first solenoid 31. As a result, the first control IC 52 controls the fuel injection timing by energizing the first solenoid 31 using the first valve drive unit 57. Since the circuit configuration of the first valve drive unit 57 has the same configuration as that of the first valve drive unit 56, the description thereof will be omitted.

The pump drive unit 60 shown in FIG. 7 is provided to drive the high-pressure fuel pump 4. When driving the high-pressure fuel pump 4, the pump drive unit 60 connects the high-pressure fuel pump 4 to the drive solenoid 61 of the high-pressure fuel pump 4 connected to the output terminals 2d to 2e of the control device 2. Drive.

The pump drive unit 60 is mainly composed of a pump drive switch 91, a pump constant current switch 92, and a pump selection switch 93, and is configured by connecting a current detection resistor 94 and diodes 95, 96, 97 in the illustrated form. The pump drive unit 60 is configured to include one pump selection switch 93. Since the configuration of the other pump drive unit 60 is based on the configuration of the first valve drive unit 56, the wiring description will be omitted. The first control IC 52 can pass a current through the drive solenoid 61 of the high-pressure fuel pump 4 by using the pump drive unit 60, and can drive and control the high-pressure fuel pump 4.

The reference drawing will be returned to FIG. 4 for explanation. The second control IC 53 drives and controls the second booster circuit 55 and the second valve drive units 58 and 59. The second booster circuit 55 boosts the power supply voltage VB based on the booster control signal input from the second control IC 53, and supplies the second booster voltage Vboost2 higher than the power supply voltage VB to the second valve drive units 58 and 59. The circuit configuration of the second booster circuit 55 is the same as that of the first booster circuit 54. Therefore, the description of the circuit configuration will be omitted. The value of the first boost voltage Vboost1 of the first booster circuit 54 and the value of the second booster voltage Vboost2 of the second booster circuit 55 may be the same as or different from each other. The charging capacitor 75 of the second booster circuit 55 corresponds to the "charging unit" according to the present invention.

The second valve drive unit 58 is connected to the output terminal of the control device 2 when driving the second valve 30 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank. Power is cut off from the solenoid 32. The second control IC 53 uses the second valve drive unit 58 to apply a current to the second solenoid 32 of the second valve 30 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank. By doing so, the fuel injection rate is changed and controlled. Since the circuit configuration of the second valve drive unit 58 is the same as the circuit configuration of the first valve drive unit 56, the description thereof will be omitted.

The second valve drive unit 59 is a second solenoid connected to the output terminal of the control device 2 when driving the second valve 30 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank. Power is cut off to 32. The second control IC 53 uses the second valve drive unit 59 to apply a current to the second solenoid 32 of the second valve 30 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank. By doing so, the fuel injection rate is changed and controlled. Since the circuit configuration of the second valve drive unit 59 is the same as the circuit configuration of the first valve drive unit 56, the description thereof will be omitted.

<Drive control processing of high-pressure fuel pump 4>
First, with reference to FIG. 8, a basic pump drive process by the high-pressure fuel pump 4 will be described. When the fuel injection device 7 ... 10 injects fuel from the injection hole 47, the pressure of the fuel accumulated in the common rail 5 decreases. The microcomputer 51 of the control device 2 detects the fuel pressure by the pressure sensor 14, and when the fuel pressure drops to the pressure lower limit threshold value or less, outputs a boost command as a pressure adjustment command signal to the first control IC 52. The first control IC 52 raises the internal pressure of the common rail 5 by driving and controlling the high-pressure fuel pump 4 by using the pump drive unit 60. As shown in FIG. 8, the drive control of the high-pressure fuel pump 4 is performed once for each crank angle of 180 ° CA. As a result, the internal pressure of the common rail 5 can be adjusted to be within a predetermined range.

The circuit operation of the pump drive unit 60 will be described with reference to FIG. 7. When the first control IC 52 receives a boost command as a pressure adjustment command signal from the microcomputer 51, the pump selection switch 93 is turned on and the pump drive switch 91 is turned on, and the first boost voltage Vboost 1 is driven by the high pressure fuel pump 4. The solenoid 61 is energized. The first control IC 52 turns off the pump drive switch 91 when the detected current of the current detection resistor 94 reaches the peak threshold value. After that, the drive current of the high-pressure fuel pump 4 decreases, but when the detection current of the current detection resistor 94 reaches a constant current range lower than the peak threshold value, the high-pressure fuel pump 4 is controlled to turn on / off the pump constant current switch 92. Keeps the drive current in a certain range. As a result, the operation of the high-pressure fuel pump 4 is maintained. Then, when the first control IC 52 receives the boost stop command of the pressure adjustment command signal from the microcomputer 51, the first control IC 52 stops the operation of the high pressure fuel pump 4 by turning off all the switches 91 to 93.

<Explanation of basic injection control processing>
Next, the basic injection control process will be described. When the internal combustion engine 11 has 4 cylinders and 4 cycles, single-shot injection or multi-stage injection such as 3 times or 5 times is performed within the range of the crank angle 180 ° CA of the front and rear crank angle signals with respect to the top dead center TDC. For example, when injecting five times, each injection is referred to as pilot injection, pre-injection, main injection, after-injection, and post-injection. For example, when injecting three times, pre-injection and post-injection are omitted.

When the control device 2 injects and controls fuel from the injection holes 47 of the fuel injection devices 7 to 10 into the cylinder of the internal combustion engine 11, the microcomputer 51 first outputs an injection start signal corresponding to each of the fuel injection devices 7 to 10. It is output to the control IC 52 and the second control IC 53.

The case where the microcomputer 51 outputs the injection start signals of the injections M and M2 from the fuel injection device 7 corresponding to the cylinder # 1 to the first control IC 52 and the second control IC 53, respectively, will be described as an example. The first control IC 52 controls the communication / disconnection of the first orifice 45a by energizing the first solenoid 31 and driving the first valve 29. In parallel with the processing of the first control IC 52, the second control IC 53 energizes the second solenoid 32 by using the second valve drive unit 58 to drive the second valve 30, thereby driving the second valve 30 of the second orifice 41a. It controls communication / shutoff and controls the fuel injection rate.

FIG. 9 shows changes in the valve drive current flowing through the first solenoid 31 and the second solenoid 32. The first control IC 52 controls the discharge switch 81 and the constant current switch 82 on while controlling the selection switch 83 on.

When the discharge switch 81, the constant current switch 82, and the selection switch 83 are turned on, the first boost voltage Vboost1 of the charging capacitor 75 of the first booster circuit 54 is applied to the first solenoid 31. Therefore, the valve drive current increases. After that, when the valve drive current reaches the peak current Ip set in the microcomputer 51, the first control IC 52 detects the peak current Ip based on the voltage detected by the current detection resistor 85 and controls the discharge switch 81 to be off. .. Then, the valve drive current decreases and reaches the pickup current Ipa.

When the first control IC 52 detects that the valve drive current has reached the pickup current Ipa, the first control IC 52 controls the constant current switch 82 on and off to maintain the pickup current Ipa. This pickup current Ipa is set lower than the peak current Ip, and is generated by using the power supply voltage VB without using the boost voltage Vboost1 charged in the charging capacitor 75 of the first booster circuit 54.

After that, when the first control IC 52 ends the command period Tp1 of the pickup current Ipa set by the microcomputer 51, the first control IC 52 further lowers the valve drive current from the pickup current Ipa, and a predetermined constant value larger than 0. The constant current switch 82 is controlled to be turned on and off so as to hold the current Ipb. This predetermined constant current Ipb is set lower than the pickup current Ipa, and is generated by using the power supply voltage VB without using the boost voltage Vboost1 charged in the charging capacitor 75 of the first booster circuit 54. After that, when the microcomputer 51 outputs an injection stop signal and the first control IC 52 receives the injection stop signal from the microcomputer 51, the constant current switch 82 is turned off to reduce the valve drive current.

On the other hand, when the second control IC 53 receives the injection start signal, the second control IC 53 controls each switch 81 to 83 on / off. As shown in the current waveform at the time of injection M2 in FIG. 9, the second control IC 53 controls the valve drive current to the peak current Ip2, then controls the pickup current Ipa2 to be lower than the peak current Ip2, and then controls the pickup current Ipa2. It is controlled to a lower predetermined constant current Ipb2. Since the on / off control process of each switch 81 to 83 executed by the second control IC 53 has the same contents as the on / off control process of each switch 81 to 83 by the first control IC 52 described above, the description thereof is omitted. do.

The second control IC 53 generates a peak current Ip2 by using the charging power charged in the charging capacitor 75 of the second boosting circuit 55 and the second boosting voltage Vboost2 based on the on / off control of the discharge switch 81. Further, the second control IC 53 generates the pickup current Ipa2 and the constant current Ipb2 by controlling the constant current switch 82 and the selection switch 83 on and off while the discharge switch 81 is off-controlled. Therefore, the pickup current Ipa2 and the constant current Ipb2 are generated by using the power supply voltage VB without using the charging power charged in the charging capacitor 75 of the second booster circuit 55 and the second booster voltage Vboost2.

Further, the microcomputer 51 sets the current set value for driving the first valve 29 (peak current Ip, pickup current Ipa, constant current Ipb) to the current set value for driving the second valve 30 (peak current Ip2, pickup current Ipa2, Set independently of the constant current Ipb2). Further, the microcomputer 51 also independently sets the energization time of these current set values according to the characteristics of the first valve 29 and the second valve 30.

However, the microcomputer 51 makes the on / off control timing of each switch 81 to 83 by the second control IC 53 the same as the on / off control timing of each switch 81 to 83 by the first control IC 52, or makes the timing different from each other. By setting to, the opening / closing control timing of the first valve 29 and the second valve 30 is adjusted. As a result, the fuel injection rate can be changed and controlled according to the above-mentioned mode. By performing such control, the control device 2 can inject fuel while changing the above-mentioned high injection rate mode, low injection rate mode, and boot injection mode.

<Normal decompression control>
Hereinafter, the processing operation when the control device 2 controls the internal pressure of the common rail 5 to reduce the pressure will be described with reference to FIGS. 8 and 10.

Normally, the control device 2 is a fuel injection device 7 corresponding to the cylinder # 1 of the first bank, a fuel injection device 9 corresponding to the cylinder # 3 of the second bank, and a fuel injection device corresponding to the cylinder # 4 of the first bank. 10. The control process of the injection M is executed in the cycle of the fuel injection device 8, ... Corresponding to the cylinder # 2 of the second bank. Therefore, the fuel injection devices 7, 9, 10, and 8 mainly inject fuel in this order. Note that FIG. 8 also shows other injections related to the multi-stage injection, but the description thereof will be omitted because they are not related to the features of the present application.

As shown in FIG. 8, after the control device 2 injects fuel from the fuel injection device 10 corresponding to the cylinder # 4 in the first bank, the fuel is injected from the fuel injection device 8 corresponding to the cylinder # 2 in the second bank. Consider the case where it is detected by either the pressure sensor 14 or the built-in pressure sensors 7a to 10a of each fuel injection device 7 to 10 that the internal pressure of the common rail 5 exceeds the pressure upper limit threshold value before injection. ..

At this time, the microcomputer 51 determines that there is a decompression request in step S2 of FIG. The microcomputer 51 sets the energization condition of the second solenoid 32 for driving the second valve 30 in step S3 of FIG. 10, and outputs a decompression command to the second control IC 53 together with the energization condition of the second solenoid 32 as a pressure adjustment command signal. do. The second control IC 53 uses the second valve drive units 58 and 59 to energize the target second solenoid 32 in step S4 of FIG. 10 to open the target second valve 30, thereby opening the target second valve 30 as described above. The internal pressure of the common rail 5 is reduced in the rail depressurizing mode.

At the timing t1 of FIG. 8, when the decompression request is generated, it is immediately before the fuel is injected from the fuel injection device 10 of the second bank # 2. Therefore, the microcomputer 51 applies the target second solenoid 32 to the cylinder in step S4. The second solenoid 32 of the fuel injection devices 7 to 9 corresponding to the cylinders # 1 to # 3 other than # 4 is used. When the second solenoid 32 of the fuel injection devices 7 to 9 is energized, the internal pressure of the common rail 5 drops in the rail depressurization mode. The microcomputer 51 energizes the target second solenoid 32 in steps S4 and S5 until the signal of the pressure sensor 14 is detected and the target pressure is reached.

Further, as shown in FIG. 8, during the fuel injection period t2 to t3 of the fuel injection device 8 corresponding to the cylinder # 2 of the second bank, the second control IC 53 is the cylinder # 3 of the same bank as the cylinder # 2. In order to control the closing of the second valve 30, the energization of the second solenoid 32 is temporarily stopped. This means that if the second valves 30 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the same second bank are simultaneously opened and controlled, the fuel injection device 8 corresponding to the same second bank , 9 will be energized to the second solenoid 32 at the same time, the consumption of charging power of the charging capacitor 75 of the second booster circuit 55 will increase significantly, and a large thermal stress will be applied to the charging capacitor 75. This is because there is a risk that the operation reliability will be impaired.

The thermal stress of the charging capacitor 75 can be reduced by controlling the second control IC 53 so that the second solenoid 32 of the fuel injection devices 8 and 9 corresponding to the same second bank is not energized at the same time. After the fuel injection period t2 to t3 by the fuel injection device 8 has elapsed, the second control IC 53 again simultaneously opens and controls the second valves 30 of the fuel injection devices 8 and 9 corresponding to the second bank, thereby inside the common rail 5. Reduce the pressure. See periods t3 to t6 in FIG.

As shown in FIG. 8, since the fuel injection device 7 corresponding to the cylinder # 1 of the first bank is used to inject fuel after the timing t4, the first control IC 52 of the control device 2 is the fuel injection device 7. During the fuel injection period t4 to t5, the second valve 30 of the fuel injection device 10 corresponding to the cylinder # 4 of the first bank is closed and controlled. Since the fuel injection device 9 corresponding to the cylinder # 3 of the second bank injects fuel after the timing t6 shown in FIG. 8, the second control IC 53 of the control device 2 injects fuel from the fuel injection device 9. After the timing t6, the second valve 30 of the fuel injection device 8 corresponding to the cylinder # 2 of the same second bank is closed and controlled.

The microcomputer 51 detects the signals of the pressure sensor 14 and the built-in pressure sensors 7a to 10a, determines that the decompression request has been completed when the target pressure is reached, and stops the energization of the target second solenoid 32 in step S6. See timing t7 in FIG. Subsequent processing is the same as the normal injection control processing.

According to the present embodiment, in the period t1 to t4 for reducing the internal pressure of the common rail 5, the second control IC 53 has the same energization period t1 to t2 and t3 to t6 of the second solenoid 32 in the target fuel injection device 9. The period is different from the energization period t2 to t3 of the second solenoid 32 during normal injection control in the other fuel injection device 8 of the bank.

Similarly, during the period t4 to t6 for reducing the internal pressure of the common rail 5, the second control IC 53 sets the energization period t1 to t4 and t5 to t7 of the second solenoid 32 in the target fuel injection device 10 to other than the same bank. The period is different from a part of the energization period t4 to t6 of the second solenoid 32 during normal injection control in the fuel injection device 7 of the above.

Therefore, even if the second control IC 53 energizes and controls a plurality of second solenoids 32 by using the second boost voltage Vboost2 of the same charging capacitor 75, the current load applied to the charging capacitor 75 can be dispersed. It can reduce heat stress. As a result, the internal pressure of the common rail 5 can be reduced without applying thermal stress to the charging capacitor 75 as much as possible.

<Processing operation in case of abnormality>
Further, a processing operation when an abnormality occurs due to a sticking failure of the high-pressure fuel pump 4 on the pumping side will be described with reference to FIG. When the microcomputer 51 of the control device 2 detects a full pressure feed failure by detecting the values of the pressure sensor 14 and the built-in pressure sensors 7a to 10a as abnormal values, the mode shifts to the full depressurization mode and the processing operation at the time of abnormality shifts. do.

In the full decompression mode, the microcomputer 51 outputs a stop command of the pressure adjustment command signal to the first control IC 52 and the second control IC 53. Then, at the same time that the first control IC 52 stops the drive control of the pump drive unit 60, the second control IC 53 sets all the fuel injection devices 7 to 10 as the target fuel injection devices 7 to 10 for decompression drive, and the target fuel injection device. The second valve 30 is opened and controlled by energizing the second solenoid 32 of 7 to 10.

FIG. 11 shows an example in which the energization start processing of the second solenoid 32 for driving the second valve 30 of all the fuel injection devices 7 to 10 is simultaneously executed at the timing t11. At this time, the valve drive current is energized to the second solenoid 32 of all the target fuel injection devices 7 to 10 via the second valve drive units 58 and 59, so that the consumption of the charging power of the charging capacitor 75 is significantly increased. Will increase.

In order to mitigate the influence of the sudden increase in the consumption of charging power, the second control IC 53 compares the peak current Ip2 that energizes the second solenoid 32 of the target fuel injection devices 7 to 10 during normal injection control. It is preferable to set it low and control the time for energizing the pickup current Ipa2 to be extended by a predetermined time Ta.

The broken line in FIG. 12 shows the valve drive current at the time of normal injection control, and the solid line in FIG. 12 shows the valve drive current at the time of abnormality. The period Tp2b for energizing the pickup current Ipa2 is set to be longer than the period Tp2 during normal injection control by a predetermined time Ta. For example, the peak current Ip2 / 2 of the valve drive current at the time of abnormality is set to half the peak current Ip2 of the valve drive current at the time of normal injection control.

The second control IC 53 sets the peak current that energizes the second solenoid 32 at the time of abnormality to be lower than the peak current Ip2 at the time of normal injection control, so that the transiently generated current is compared with the conventional technique. It can be suppressed and the thermal stress generated in the charging capacitor 75 can be reduced.

Further, since the energization time of the pickup current Ipa2 is extended by Ta for a predetermined time, the integrated amount of the energization current also increases. Since the opening degree of the second valve 30 is determined based on the integrated amount of the energizing current, the second valve 30 can be reliably opened and controlled so as not to be different from the normal injection control.

Further, it is desirable to set Ta for a predetermined time according to the characteristics of the fuel injection devices 7 to 10. For example, the mechanical or electrical characteristics of the fuel injection devices 7 to 10 are obtained in advance by experiments or simulations, and the correspondence map of the predetermined time Ta according to these characteristics is non-volatilely stored in the internal memory of the second control IC 53. It is good to do it. Then, the second control IC 53 refers to this correspondence map and controls Ta for a predetermined time according to the measured values of the peak current Ip2 / 2 and the pickup current Ipa2 to open the second valve 30 more reliably. Can be controlled.

<Modification example of processing during normal injection control>
In the above, the peak current of the valve drive current at the time of abnormality is shown to be lower than the peak current Ip of the valve drive current at the time of normal injection control, but when there is a decompression request at the time of normal injection control. However, the second control IC 53 sets the peak current of the valve drive current to be lower than the peak current Ip at the time of normal injection control, and executes control in which the time for energizing the pickup current Ipa2 is extended by a predetermined time Ta. You may try to do it. At this time, similarly to the above, it is preferable to set the peak current Ip / 2 of the valve drive current to half the peak current Ip at the time of normal injection control, and set the predetermined time Ta longer. As a result, the same effect as described above is obtained.
In the above description, when a decompression request is made during normal injection control or abnormal time, the peak current Ip / 2 of the valve drive current is set to half the peak current Ip of the valve drive current during normal injection control. Although shown, it is not limited to half the amount.

<Modification example of processing during normal injection control or abnormal condition>
As another method, it is desirable to shift the energization timing of the peak current Ip2 by shifting the energization start timing of each of the second solenoids 32 for driving the second valves 30 of the fuel injection devices 7 to 10. For example, as shown in the timing t21 of FIG. 13, after the energization of each second solenoid 32 for driving the second valves 30 of the fuel injection devices 7 and 10 is started, the fuel injection devices 8 and 9 are charged at the timing t22. It is advisable to start energizing each second solenoid 32 for driving the two valves 30. As a result, the transiently generated current can be suppressed as compared with the conventional case, and the thermal stress generated in the charging capacitor 75 of the second booster circuit 55 can be reduced. The second solenoids 32 of the fuel injection devices 8 and 9 may be energized before the second solenoids 32 of the fuel injection devices 7 and 10.
Conventionally, the common rail 5 is provided with a pressure reducing valve, but if fuel can be discharged from the low pressure chamber 36 of the fuel injection device 7 to 10 as in the present embodiment, it is not necessary to provide the pressure reducing valve on the common rail 5. In addition to the configuration of this embodiment, a pressure reducing valve may be provided on the common rail 5.

(Second Embodiment)
With reference to FIGS. 14 and 15, the processing operation when the control device 2 controls the reduction of the internal pressure of the common rail 5 will be described. As shown in FIG. 14, consider a case where a full pumping failure occurs after the control device 2 injects and controls fuel from the fuel injection device 7 corresponding to the cylinder # 1 of the first bank.

While the control device 2 is performing normal injection control in S11 of FIG. 15, when the microcomputer 51 determines that there is a depressurization request in S12 and S13 and there is no injection request, the second valve 30 is pressed in S14 of FIG. The energization condition of the second solenoid 32 to be driven is set, and the decompression command is output to the second control IC 53 together with the energization condition of the second solenoid 32 as a pressure adjustment command signal. The second control IC 53 opens the target second valve 30 by energizing the target second solenoid 32 in S15, thereby reducing the internal pressure of the common rail 5 in the full decompression mode. After that, as shown in S16 to S18 of FIG. 15, if the internal pressure of the common rail 5 reaches the target pressure without injection request, the control device 2 stops the energization of the target second solenoid 32 to fully reduce the pressure. Exit the mode.

However, when the microcomputer 51 generates an injection request based on the sensor signal S, it determines NO in S16, stops energizing the target second solenoid 32, returns the processing to S11, and performs the processing of S11 to S13. repeat.

At this time, since the control device 2 has shifted to the full decompression mode, the microcomputer 51 moves from the first control IC 52 to the first solenoid 31 of the fuel injection device 9 by the first valve drive unit 57 in response to the injection request. After the energization is started and the energization to the first solenoid 31 is completed, the energization of the second solenoid 32 of the fuel injection device 9 is started from the second control IC 53 by the second valve drive unit 59. See timings t31 and t32 in FIG.

The first control IC 52 controls the peak current Ip, the pickup current Ipa, and the constant current Ipb using the set values set in the internal memory. The second control IC 53 controls the peak current Ip2, the pickup current Ipa2, and the constant current Ipb2 by using the set values set in the internal memory.

At the time of timing t31, the internal memory of the first control IC 52 and the second control IC 53 stores the set values in each mode set in the microcomputer 51, for example, the low injection rate mode and the high injection rate mode. ..

Therefore, the first control IC 52 controls opening and closing of the first valve 29 according to the set value corresponding to each mode, and then the second control IC 53 opens and closes the second valve 30 according to the set value corresponding to each mode. Can be controlled. The microcomputer 51 continues injection control by controlling the opening and closing of the first valve 29 by the first control IC 52, and then lowers the internal pressure of the common rail 5 by controlling the opening and closing of the second valve 30 by the second control IC 53. Can be made to.

After that, the microcomputer 51 depressurizes the common rail 5 by energizing the target second solenoid 32 again in S14. See timings t32 to t33 in FIG. Further, when the injection request corresponding to the sensor signal S is generated again, the microcomputer 51 stops energizing the target second solenoid 32 in S19, and shifts to the normal control in S11. Since the above-mentioned set values are stored in advance by the microcomputer 51 in the internal memories of the first control IC 52 and the second control IC 53, injection control can be performed as usual according to the demands of the low injection rate mode and the high injection rate mode. You can continue. See timings t33 to t34 in FIG.

According to the present embodiment, after the first control IC 52 finishes energizing the first solenoid 31 for driving the first valve 29, the second control IC 53 goes to the second solenoid 32 for driving the second valve 30. Is starting to energize.
The first valve 29 and the second valve 30 can be controlled to open and close by sequentially energizing the first solenoid 31 and the second solenoid 32 while ensuring the controllability of the low / high injection rate in each mode, whereby the low / high injection rate can be controlled. It is possible to meet decompression requirements while ensuring controllability of high injection rate.

(Third Embodiment)
In this embodiment, a method for controlling the change of the peak current Ip at the time of abnormality will be described. When the control device 2 generates a decompression request at the time of the above-mentioned normal injection control or an abnormality and lowers the internal pressure of the common rail 5, the second control IC 53 is in the normal injection control as shown in FIG. The pickup current Ipaa is controlled without controlling the peak current Ip. Then, as shown in FIG. 16, the second control IC 53 can control the peak current Ipm to be the same as the pickup current Ipaa. As a result, the peak current Ipm can be made significantly lower than the peak current Ip at the time of normal injection control.

In this case, the second control IC 53 controls the constant current switch 82 to be turned on and off so that the peak current Ipm is reached by energizing the second solenoid 32 from the power supply voltage VB, so that the charging power of the charging capacitor 75 is reached. Is not used. As a result, the charging power of the charging capacitor 75 is not consumed, and the thermal stress applied to the charging capacitor 75 can be significantly reduced.

(Other embodiments)
The present disclosure is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof. For example, the following modifications or extensions are possible.

Although the configuration is shown in which the fuel is returned from the fuel injection devices 7 to 10 to the fuel tank 12 through the low pressure pipe 38, a pressure reducing valve may be provided on the common rail 5. When the pressure reducing valve is provided on the common rail 5, the pressure may be reduced from the pressure reducing valve or the fuel injection devices 7 to 10.
When the common rail 5 is not provided with the pressure reducing valve, the pressure may be reduced from the fuel injection devices 7 to 10. As the pressure sensor 14, the built-in pressure sensors 7a to 10a of the fuel injection devices 7 to 10 may be used, or the pressure sensor 14 provided on the common rail 5 may be used.

The first control IC 52 and the second control IC 53 may be configured in an integrated integrated circuit, may be configured in a separate integrated circuit, or may be integrated with the microcomputer 51 to form a control unit. You may. The first control chamber 43 and the second control chamber 49 may be configured as an integral chamber.

Although N-channel type MOS transistors are used as various switches 81 to 84 and 91 to 93, the present invention is not limited to this, and various transistors and switching elements can be applied.
Although only one second orifice 41a is provided in the second passage 41, a plurality of passages connecting the low pressure chamber 36 and the first control chamber 43 may be provided, and the second orifice 41a may be provided. It may be provided in each of a plurality of passages. That is, at least one second orifice 41a may be provided.

Further, in the above-described embodiment, since the internal combustion engine 11 includes four cylinders, two of the cylinders # 1 to # 4 corresponding to the plurality of fuel injection devices 7 to 10 are used as cylinders # 1 and # 4 in the first bank, respectively. , The form treated as cylinders # 2 and # 3 of the second bank is shown, but the present invention is not limited to this. It can be applied even with 6 cylinders.

The configurations of each embodiment can be applied in combination as appropriate. An embodiment in which a part of the above-described embodiment is omitted as long as the problem can be solved can also be regarded as an embodiment. In addition, any conceivable embodiment can be regarded as an embodiment as long as it does not deviate from the essence of the invention specified by the wording described in the claims.

Although the present disclosure has been described in accordance with the embodiments described above, it is understood that the present disclosure is not limited to such embodiments or structures. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms, including one element, more, or less, are within the scope and ideology of the present disclosure.

In the drawing, 2 is a fuel injection control device, 5 is a common rail, 7 to 10 is a fuel injection device, 11 is an internal combustion engine, 27 is a hydraulically driven valve, 29 is a first valve, 30 is a second valve, and 31 is a first solenoid. 32 is the second solenoid, 36 is the low pressure chamber, 41 is the second passage, 41a is the second orifice, 43 is the first control chamber (control chamber), 45 is the first passage, 45a is the first orifice, 47 is the injection. Hole, 49 is the second control room (control room), 52 is the first control IC (first control unit), 53 is the second control IC (second control unit), and 75 is the charging capacitor (second booster circuit 55). The charging capacitor 75 indicates a "charging unit").

Claims (8)

It is a fuel injection control device that injects and controls the fuel from the common rail (5) in which the fuel is stored to the internal combustion engine (11) by using a plurality of fuel injection devices (7 to 10).
The plurality of fuel injection devices include a first solenoid (31), a first valve (29), a second solenoid (32), and a second valve (30), respectively.
During normal injection control, the first control unit (52) that drives the first valve by energizing the first solenoid to control the fuel injection timing,
During the normal injection control, the charging power of the charging unit (75) is used to energize the second solenoid with a peak current (Ip2) indicating the maximum current, and then a pickup current (Ipa2) lower than the peak current is applied. A second control unit (53) that drives the second valve by energizing to control the injection rate of the fuel is provided.
When the internal pressure of the common rail is reduced at the time of the normal injection control or an abnormal time different from the normal injection control, the first control unit closes the first valve and the second control unit controls the closing. It is configured to open and control the second valve by energizing the second solenoid in at least one or more target fuel injection devices among the plurality of fuel injection devices.
When the internal pressure of the common rail is reduced at the time of the normal injection control or an abnormal time different from the normal injection control, the second control unit energizes the second solenoid of the target fuel injection device. A fuel injection control device that sets the peak current lower than that during the normal injection control and executes control by extending the time for energizing the pickup current by a predetermined time. The first aspect of the present invention, wherein when the internal pressure of the common rail is reduced during the normal injection control or the abnormal time, the second control unit reduces the peak current by half as compared with the normal injection control. Fuel injection control device. When the internal pressure of the common rail is reduced during the normal injection control or the abnormal time, the second control unit does not execute the control of the peak current using the charging power of the charging unit (75). The fuel injection control device according to claim 1, wherein the pickup current is controlled. The fuel injection control device according to any one of claims 1 to 3, wherein the second control unit sets the predetermined time according to the characteristics of the fuel injection device. A fuel injection control device that injects and controls the fuel from a common rail on which fuel is stored to an internal combustion engine using a plurality of fuel injection devices.
The plurality of fuel injection devices include a first solenoid (31), a first valve (29), a second solenoid (32), and a second valve (30), respectively.
During normal injection control, the first control unit (52) that drives the first valve (29) by applying a current to the first solenoid to control the fuel injection timing,
At the time of the normal injection control, the second valve (30) of the plurality of fuel injection devices (8, 9) is energized by energizing the plurality of second solenoids by using the charging power of the same charging unit (75). ), And a second control unit (53) for changing and controlling the fuel injection rate.
When the internal pressure of the common rail is reduced at the time of the normal injection control or an abnormal time different from the normal injection control, the first control unit closes the first valve and the second control unit controls the closing. It is configured to open and control the second valve by energizing the second solenoid in at least one or more target fuel injection devices among the plurality of fuel injection devices.
During the period for reducing the internal pressure of the common rail, the second control unit sets the energization period of the second solenoid in the target fuel injection device to the second during the normal injection control in the other fuel injection device. A fuel injection control device whose period is different from the energization period of the solenoid. When two of the plurality of cylinders provided corresponding to the plurality of fuel injection devices are each set as one bank.
The fuel injection control device according to claim 5, wherein the second control unit controls the energization period of the second solenoid of the two fuel injection devices corresponding to the two cylinders in the same bank so as to be different. When the first control unit energizes the first solenoid for driving the first valve at the time of the abnormality,
After the first control unit ends energization of the first solenoid for driving the first valve, the second control unit starts energization of the second solenoid for driving the second valve. The fuel injection control device according to claim 5 or 6. The fuel injection device is
The nozzle needle (25) that injects the fuel supplied from the common rail through the high-pressure fuel flow path (35) from the injection hole (47), and the fuel is accumulated in the back of the nozzle needle and the injection of the nozzle needle. A control chamber (43, 49) for controlling the fuel injected from the hole, a hydraulic driven valve (27) provided inside the control chamber and driven by the pressure of the high-pressure fuel flow path and the control chamber, and the above. The first passage (45) provided inside the hydraulically driven valve inside the control chamber, the first orifice (45a) limiting the first passage, and the said without going through the inside of the hydraulically driven valve. At least one second passage (41) connecting the control chamber and the low pressure chamber (36), at least one second orifice (41a) limiting the second passage, and not being injected from the injection hole. It is configured to include the low pressure chamber (36) provided for discharging the fuel.
The first control unit energizes the first solenoid to drive the first valve, and the second control unit energizes the second solenoid to drive the second valve to drive the second orifice of the second orifice. It is configured to control communication / interruption,
When the internal pressure of the common rail is reduced, the hydraulically driven valve is driven by controlling the closing of the first valve by the first solenoid and opening the second valve by the second solenoid to drive the second valve. By communicating the high-pressure fuel flow path, the control chamber, and the low-pressure chamber from the common rail through an orifice, the fuel can be introduced without injecting the fuel into the internal combustion engine from the injection hole of the nozzle needle. The fuel injection control device according to any one of claims 1 to 7, which is configured to flow out from the low pressure chamber to reduce the internal pressure of the common rail.

Images