JP2021092194A - Control device - Google Patents

Abstract

To provide a control device capable of properly keeping a valve opening holding current of an object valve without increasing supply current to two solenoids to double for driving the object valve for two cylinders.SOLUTION: Common nodes N11 and N12 electrically connect one ends of second solenoids 32_#1 and 32_#4 driving second valves 30 of fuel injection devices 7 and 10 for two cylinders respectively in common. A recovery switch 90b1 is connected between the node N11 and a power supply node N0. A second control IC 53 executes serial connection control for simultaneously controlling driving currents of the second solenoids 32_#1 and 32_#4 by on/off controlling the recovery switch 90b1 while on-controlling a selection switch 84b1 in a state of connecting the second solenoids 32_#1 and 32_#4 in series between the power supply node N0 and a ground node through the common node N11.SELECTED DRAWING: Figure 12

Description

The present invention relates to a control device for fuel injection.

Conventionally, the applicant has proposed a fuel injection device incorporating two valves, for example, for controlling the fuel injection rate. A recent fuel injection control system is configured to inject fuel while controlling the fuel injection rate by two valves built in the fuel injection device. The fuel injection rate can be controlled by adjusting the decompression rate of the fuel stored in the control chamber, and is known to be proportional to the decompression rate of the stored fuel in the control chamber.

Further, the fuel injection control system is configured so that when a decompression request is generated, for example, the oil pressure can be depressurized by opening and controlling the target valve used for decompression while keeping the other valves of a certain fuel injection device closed. In this case, the fuel pressure can be reduced. Thereby, for example, the fuel pressure can be adjusted to the target pressure even during normal control or when the high-pressure fuel pump sticks and fails on the pumping side (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-39424

The inventor is considering independently driving one of the two valves built into the fuel injection device, which is the target valve, for two or more cylinders at the same time. For example, in the current fuel injection system, one end of two solenoids (corresponding to the first solenoid and the second solenoid) for driving the target valves for two cylinders is electrically and commonly connected by a common node, and the two solenoids are connected. Solenoids are connected in parallel, and one of the solenoids is selectively energized to control fuel injection.

When the control device attempts to drive and control the target valves for two cylinders at the same time, it is necessary to select the two solenoids while connecting the two solenoids in parallel and supply the current for holding the valve open of the target valves. Then, the supply current must be significantly increased, which is not preferable because high-spec parts are required for the peripheral circuit.

An object of the present invention is to provide a control device capable of appropriately maintaining the valve opening holding current of the target valve without having to significantly increase the supply current to the two solenoids for driving the target valves for two cylinders. To provide.

According to the invention of claim 1, it has the following configuration. The common nodes (N11, N12) are one ends of the first solenoid (32_ # 1, 32_ # 2) and the second solenoid (32_ # 4, 32_ # 3) that drive the target valves of the fuel injection device for two cylinders, respectively. Are electrically connected in common. The first energizing nodes (N21, N22) are provided on the opposite side of the common node with respect to the first solenoid. The second energizing nodes (N31, N32) are provided on the opposite side of the common node with respect to the second solenoid. The first switch (83b1, 84b1, 83b2, 84b2) is connected either between the first energizing node and the ground node, or between the second energizing node and the ground node.

The booster circuit (55) supplies a boosted power source whose power supply voltage is boosted to the power supply node (N0). The second switch (90b1, 90b2) is connected between at least one of the first energized node and the second energized node and the power supply node. The control circuit (50) turns on one of the first switch and the second switch in a state where the first solenoid and the second solenoid are connected in series between the power supply node and the ground node via the common node. The series connection control that simultaneously controls the drive currents of the first solenoid and the second solenoid is executed by controlling the other on and off while controlling.

For example, in a state where the control circuit connects the first solenoid and the second solenoid in series between the power supply node to which the boost power of the booster circuit is supplied and the ground node via the common node, the first switch is operated. When the second switch is turned on / off while being turned on, the current can be controlled while the same current is passed through the first solenoid and the second solenoid based on the boosted power supply.

For example, similarly, in the control circuit, the first solenoid and the second solenoid are connected in series between the power supply node to which the boost power supply of the booster circuit is supplied and the ground node via the common node, and the second solenoid is connected. When the first switch is turned on / off while the switch is turned on, the current can be controlled while the same current is passed through the first solenoid and the second solenoid based on the boosted power supply. This eliminates the need to significantly increase the current supplied to the first solenoid and the second solenoid. This eliminates the need to use high-spec parts. Moreover, the valve opening holding current of the target valve can be appropriately maintained.

Configuration diagram of the fuel injection control system according to the first embodiment Cross-sectional view of the fuel injection device according to the first embodiment The figure explaining the flow when the fuel pressure is lowered in 1st Embodiment Block diagram showing an electrical configuration in the first embodiment Circuit diagram of the first valve drive unit in the first embodiment Circuit diagram of the second booster circuit in the first embodiment Circuit diagram of the second valve drive unit in the first embodiment Timing chart showing the second solenoid energizing current during normal control in the first embodiment Flow chart showing the operation in the first embodiment The figure which shows typically the 2nd solenoid energization current at the time of the normal injection control in 1st Embodiment The figure which shows typically the 2nd solenoid energization current at the time of decompression control in 1st Embodiment Explanatory drawing of current energization path in series connection control of 1st Embodiment A timing chart for explaining the on / off timing of each switch in the first embodiment. Explanatory drawing explaining the technical significance of 1st Embodiment A timing chart showing a change in the boosted voltage of the second booster circuit in the second embodiment. Explanatory drawing of energization path in parallel connection control of 3rd Embodiment A timing chart for explaining the on / off timing of each switch in the third embodiment. Timing chart showing the temperature change of the booster circuit in the third embodiment The figure which shows schematic the arrangement method of the temperature detection part in 4th Embodiment Timing chart showing the temperature change of the booster circuit in the fourth embodiment

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)
1 to 14 show explanatory views of the first embodiment. First, the overall 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 a four-cylinder configuration is shown, but it may be two cylinders or six cylinders, and it may be two or more cylinders. Further, in the present embodiment, of the four cylinders, the two cylinders of cylinders # 1 and # 4 will be referred to as a first bank, and the two cylinders of cylinders # 2 and # 3 will be referred to as a 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 of the control device 2 (see FIG. 4 described later) 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 obtain high-pressure fuel and supplies the low-pressure fuel to the common rail 5 through the high-pressure fuel pipe 13. The common rail 5 is provided to supply high-pressure 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 the fuel injection devices 7 to 10 through the high-pressure pipe 16 while maintaining the high pressure.

The common rail 5 is provided 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 formed 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 controls fuel injection through the fuel injection devices 7 to 10 based on various sensor signals S including a crank angle signal.

<Basic configuration and operation description 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 cylinders # 1 to # 4 of the internal combustion engine 11, and are also referred to as injectors or fuel injection valves. As shown in FIG. 1, each fuel injection device 7 to 10 is provided with a built-in pressure sensor 7a to 10a. 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 structure description of the fuel injection devices 8 to 10 will be omitted.

As shown in FIG. 2, the fuel injection device 7 includes a first member 21, a second member 22, a third member 23, a fourth member 24, a nozzle needle 25, a spring 26 for the nozzle needle 25, a hydraulic driven valve 27, and the like. It mainly includes a spring 28 for the flood control driven valve 27, a first 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 present embodiment is characterized by an operation or the like when the second solenoid 32 is controlled for two cylinders or more. Therefore, in the following, when the second solenoid 32 is described for each of the target cylinders # 1 to # 4, it may be referred to as the second solenoid 32_ # 1, 32_ # 2, 32_ # 3, 32_ # 4. For example, the second solenoids 32_ # 1 and 32_ # 2 form the equivalent of the "first solenoid", and for example, the second solenoids 32_ # 4 and 32_ # 3 form the equivalent of the "second solenoid".

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 members 21 to 23 are assembled, the first high-pressure fuel flow path 35 is configured to penetrate through the 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 connected to 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 in a direction closer to the third passage 39. In this case, since the first valve 29 is closed, the low pressure chamber 36 and the third passage 39 are 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 low pressure chamber 36 and the second passage 41 are 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 be communicated 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 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 first because the second high-pressure fuel flow path 35a is provided with a plurality of third orifices 35aa and the flow path area of the second high-pressure fuel flow path 35a is small. It may be configured as 3 orifices 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 flood control driven valve 27. Even if the second passage 41 is provided with a plurality of second orifices 41a, or the structure of the second passage 41 itself is configured as the second orifice 41a by making the flow path area of the second passage 41 small. good.

The annular chamber 42 is configured to be annular and is configured to communicate with the first control chamber 43 through an opening on the side of the third member 23. 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 room 43 and the second control room 49. The connecting passage 44 includes a fourth orifice 44a, which 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 be.

A flood control 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 a 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 the direction of 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 is communicated 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 flood control 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 is communicated with the first control chamber 43 without passing through the first passage 45, and the annular chamber 42 is also communicated 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 flood control driven valve 27. That is, the second passage 41 directly communicates between the low pressure chamber 36 and 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, 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 reciprocally slidable in the vertical direction shown in 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 # 1 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, the fuel injection control system 1 can communicate / shut off the high pressure chamber 46 and the inside of the cylinder # 1 of the internal combustion engine 11 based on the internal pressures of the first control chamber 43 and the second control chamber 49.

<Explanation of pressure changes in each chamber inside the fuel injection devices 7 to 10>
The fuel injection control system 1 operates in various modes such as a low injection rate mode, a high injection rate mode, a normal control mode consisting of a boot injection mode, and a rail decompression mode, and the control device 2 operates in these modes. The internal pressure of the common rail 5 can be lowered by controlling the injection of fuel from the injection holes 47 of each fuel injection device 7 to 10 or controlling the discharge of fuel to the fuel tank 12 through the fuel injection devices 7 to 10. Hereinafter, the pressure change in each chamber inside the fuel injection device 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, and both the first valve 29 and the second valve 30 are closed as illustrated in FIG. When the first valve 29 is closed, the third passage 39 and the low pressure chamber 36 are cut off. 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 (normal control 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 flood control driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22. Since the opening of the annular chamber 42 on the third member 23 side is closed by the flood control 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 restricted to be relatively narrow, the speed at which the first control chamber 43 reaches the medium pressure state also becomes slow. 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 change in the injection rate becomes relatively small.

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 initial state.

<High injection rate mode (normal control 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 so that the first valve 29 and the second valve 30 are opened substantially at the same time from the initial state.

When the first valve 29 and the second valve 30 open substantially 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 into the low pressure chamber 36 via the second passage 41. At this time, the second orifice 41a acts and the flow rate of 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.

Due to the action of the fuel pressure inside the first control chamber 43, the flood control driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22. Since the opening on the side of the third member 23 of the annular chamber 42 is closed by the flood control 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 wider than that in the low injection rate mode described above, the speed at which the first control chamber 43 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 change in the injection rate becomes relatively large.

After that, even if the second valve 30 is closed, there is almost no change in the internal oil 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 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 (normal control 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. Due to the action of the fuel pressure inside the first control chamber 43, the flood control driven valve 27 is attracted to the side of the intermediate chamber 40 of the second member 22. Since the opening on the side of the third member 23 of the annular chamber 42 is closed by the flood control 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 slides the nozzle needle 25 toward the second control chamber 49 along the cylinder 48. 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 flow path of the fuel through the first orifice 45a is restricted to be relatively narrow, 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 change in the injection rate becomes relatively small. After that, when the second valve 30 is opened, the fuel in the first control chamber 43 flows into the low pressure chamber 36 through 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 change in the injection rate becomes relatively large.

After that, even if the second valve 30 is closed, there is almost no change in the internal oil 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 initial state.

<Rail decompression mode>
Hereinafter, the rail decompression mode will be described with reference to FIG. The fuel injection control system 1 is provided with a rail depressurization mode in order to reduce the internal pressure of the common rail 5. In this rail decompression mode, the control device 2 energizes the second solenoid 32 by de-energizing the first solenoid 31 from the initial state to control the closing of the first valve 29 and keeps the first valve 29 in the closed state. 2 Valve 30 is opened and controlled.

As described above, in the initial state, the hydraulically driven valve 27 is urged by the spring 28, and the hydraulically driven valve 27 is in contact with the second member 22. In this initial state, when the second valve 30 is opened by energizing the second solenoid 32 by the control device 2, the stored fuel in the first control chamber 43 is discharged to the low pressure chamber 36 through the second passage 41, and the first The internal pressure of the control chamber 43 becomes low.

The accumulated 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 chamber 43 and the intermediate chamber 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 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 into the low-pressure chamber 36, and from the low-pressure chamber 36 through the low-pressure pipe 38. It is discharged to the fuel 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 injection control system 1 can discharge the fuel from the low pressure chamber 36 without injecting the fuel from the injection holes 47 into the cylinders # 1 to # 4 of the internal combustion engine 11, and can reduce the internal pressure of the common rail 5. Can be lowered.

In summary, the control device 2 drives the hydraulic driven valve 27 by opening and controlling the second valve 30 by the second solenoid 32 to communicate with the second orifice 41a, and from the common rail 5, the high-pressure fuel flow paths 35, 35a, By communicating the first control chamber 43 and the low pressure chamber 36, the fuel can flow out from the low pressure chamber 36 and the internal pressure of the common rail 5 can be lowered. That is, the second valve 30 is a valve capable of controlling the fuel injection rate, and has a configuration corresponding to a pressure reducing valve and a target valve, which are also used for reducing pressure among the two valves.

As shown above, the control device 2 can reduce the internal pressure of the common rail 5 by using at least one fuel injection device (for example, 7) in the rail depressurization mode. Further, a mode in which the processing operation of the rail decompression mode is executed by using all the fuel injection devices 7 to 10 is referred to as a full decompression mode. In this full depressurization mode, the control device 2 can quickly reduce the internal pressure of the common rail 5 by using all the fuel injection devices 7 to 10.

<Explanation of electrical configuration of control device 2>
Next, the electrical configuration of the control device 2 constituting the drive system circuit of the fuel injection devices 7 to 10 will be described with reference to FIG. The control device 2 operates by supplying power to the power supply voltage VB based on the battery voltage. Here, a specific example in which the power supply voltage VB is a 12V system is shown, but it may be a 24V system or can be changed as appropriate. As shown in FIG. 4, 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, and a first valve drive unit. It includes 56, 57, second valve drive units 58, 59, and a pump drive unit 60.

In the present embodiment, the microcomputer 51, the first control IC 52, and the second control IC 53 form a control circuit 50, but the control circuit 50 may be composed of one semiconductor integrated circuit device such as a microcomputer, or a plurality of control circuits 50. It may be configured by combining semiconductor integrated circuit devices.

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 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) of 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. doing.

This set value is the peak current Ip, Ip2 value, the pickup current Ipa, Ipa2 value, the constant current Ipb, Ipb2 value, and their energization, which are the maximum currents that energize the first solenoid 31 and the second solenoid 32, respectively. Includes duration. 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 by the pump drive unit 60.

The first control IC 52 and the second control IC 53 are, for example, integrated circuit devices based on ASICs, and include, for example, a logic circuit, a control main body such as a CPU, and memories such as RAM, ROM, and EEPROM, and are based on hardware and software. Is configured to perform 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 sets the first boost voltage Vboost1 higher than the power supply voltage VB to the first valve drive units 56, 57 and the pump drive unit. Supply to 60. The first booster circuit 54 has the same circuit configuration as the second booster circuit 55, but the circuit configuration of the second booster circuit 55 will be described later, and the description of the circuit configuration of the first booster circuit 54 will be omitted.

The first valve drive unit 56 is a first solenoid connected to the output 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. Energize 31. The first control IC 52 applies a current to the first solenoid 31 of the first valve 29 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank by using the first valve drive unit 56. This controls the fuel injection timing.

As illustrated in FIG. 5, the first valve drive unit 56 is mainly composed of a discharge switch 81a1, a constant current switch 82a1, selection switches 83a1, 84a1, and further combined with a current detection resistor 85a1 and diodes 87a1 to 90a1. ing. The discharge switch 81a1, the constant current switch 82a1, and the selection switches 83a1 and 84a1 are each composed of, for example, an n-channel type MOS transistor. The discharge switch 81a1 is provided as a discharge circuit that normally energizes the peak current Ip. The constant current switch 82a1 and the diode 87a1 are provided as a constant current circuit for normal constant current control.

The first valve drive unit 56 energizes the first solenoids 31_ # 1 and 31_ # 4 connected between the upstream terminals 2a1a and the downstream terminals 2a1b and 2a1c of the control device 2, respectively, so that the cylinder # of the first bank # It drives the first valve 29 of the fuel injection devices 7 and 10 corresponding to 1 and # 4. As a result, the first control IC 52 opens and closes and drives the first valve 29 for two cylinders by applying a current to the first solenoids 31_ # 1 and 31_ # 4 by using the first valve driving unit 56. The first control IC 52 controls the fuel injection timing related to the cylinders # 1 and # 4 by driving and controlling the first valve driving unit 56.

The first boost voltage Vboost1 of the first boost circuit 54 is input to the drain of the MOS transistor serving as the input terminal of the discharge switch 81a1. The discharge switch 81a1 can energize the upstream terminal 2a1a of the control device 2 with the first boost voltage Vboost1 input to the input terminal according to the control signal given to the control terminal of the discharge switch 81a1 from the first control IC 52. There is.

Between the input node of the power supply voltage VB and the upstream terminal 2a1a of the control device 2, the drain source of the MOS transistor constituting the constant current switch 82a1 and the anode cathode of the diode 87a1 are connected in series. Further, the diode 88a1 is connected in the opposite direction between the upstream terminal 2a1a of the control device 2 and the ground node. The diodes 87a1 and 88a1 are provided to prevent energization from the upstream terminal 2a1a to the supply terminal side of the power supply voltage VB and from the upstream terminal 2a1a to the ground node side, respectively.

A first solenoid 31_ # 1 for driving the first valve 29 of the fuel injection device 7 related to the cylinder # 1 is connected between the upstream terminal 2a1a and the first downstream terminal 2a1b of the control device 2. The first solenoid 31_ # 1 opens the first valve 29 of the fuel injection device 7 when energized. When the first solenoid 31_ # 1 is de-energized, the first valve 29 is closed by the urging force of the first spring 33.

A diode 89a1 is forwardly connected between the second downstream terminal 2a1c of the control device 2 and the power supply node N0 of the first boost voltage Vboost1 of the first booster circuit 54. When the first control IC 52 receives the injection stop command as an injection signal from the microcomputer 51, the diode 89a1 uses the stored energy based on the current flowing in the first solenoid 31_ # 4 as the charging capacitor of the first booster circuit 54. It is provided to regenerate to 75.

A first solenoid 31_ # 4 for driving the first valve 29 of the fuel injection device 10 of the cylinder # 4 is connected between the upstream terminal 2a1a and the second downstream terminal 2a1c of the control device 2. The first solenoid 31_ # 4 opens the first valve 29 of the fuel injection device 10 when energized, and closes the first valve 29 when the fuel injection device 10 is de-energized.

A diode 90a1 is forwardly connected between the first downstream terminal 2a1b of the control device 2 and the power supply node N0 of the first boost voltage Vboost1 of the first booster circuit 54. When the first control IC 52 receives the injection stop command as an injection signal from the microcomputer 51, the diode 90a1 uses the stored energy based on the current flowing in the first solenoid 31_ # 4 as the charging capacitor of the first booster circuit 54. It is provided to regenerate to 75.

Between the first downstream terminal 2a1b of the control device 2 and the ground node, the drain / source of the MOS transistor constituting the selection switch 83a1 and the current detection resistor 85a1 are connected in series. Between the second downstream terminal 2a1c of the control device 2 and the ground node, the drain / source of the MOS transistor constituting the selection switch 84a1 and the current detection resistor 85a1 are connected in series.

The selection switches 83a1 and 84a1 are usually provided to select the fuel injection devices 7 and 10 for injecting fuel.

The current detection resistor 85a1 detects the current flowing through the first solenoid 31_ # 1 of the fuel injection device 7 while the selection switch 83a1 is turned on. This detected value is input to the first control IC 52. The current detection resistor 85a1 detects the current flowing through the first solenoid 31_ # 4 of the fuel injection device 10 while the selection switch 84a1 is turned on. This detected value is input to the first control IC 52.

The first control IC 52 controls the discharge switch 81a1, the constant current switch 82a1, and the selection switches 83a1 and 84a1 on and off based on the set value set by the microcomputer 51, the injection signal, and the detection current of the current detection resistor 85a1. .. Since the first valve drive unit 56 is configured in this way, the first control IC 52 can perform current energization / cutoff control of the first solenoids 31_ # 1 and 31_ # 4 by using the first valve drive unit 56. , The first valve 29 of the fuel injection devices 7 and 10 of the cylinders # 1 and # 4 can be controlled to open and close.

When the first valve drive unit 57 drives the first valve 29 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank, the upstream terminal 2a2a and the downstream terminal 2a2b of the control device 2 and the downstream terminal 2a2b The first solenoids 31_ # 2 and 31_ # 3 connected to 2a2c are energized and cut off, respectively. As a result, the first control IC 52 controls the fuel injection timing by energizing the first solenoids 31_ # 2 and 31_ # 3 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 as illustrated in FIG. 5, the description will be omitted with reference numerals similar to the corresponding configurations. As illustrated in FIG. 5, the upstream terminals 2a1a, downstream terminals 2a1b and 2a1c of the first valve drive unit 56 correspond to the upstream terminals 2a2a, downstream terminals 2a2b and 2a2c of the first valve drive unit 57. The switches 81a1, 82a1, 83a1 and 84a1 configured in the first valve drive unit 56 correspond to the switches 81a2, 82a2, 83a2 and 84a2 of the first valve drive unit 57. The current detection resistor 85a1 of the first valve drive unit 56 corresponds to the current detection resistor 85a2 of the first valve drive unit 57. The diodes 87a1, 88a1, 89a1 and 90a1 of the first valve drive unit 56 correspond to the diodes 87a2, 88a2, 89a2 and 90a2 of the first valve drive unit 57.

The first valve drive unit 57 drives the upstream terminals 2a2a and the downstream terminals 2a2b and 2a2c 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 first solenoids 31_ # 2 and 31_ # 3 connected to and are energized. The first control IC 52 uses the first valve drive unit 57 to use the first solenoids 31_ # 2 and 31_ # 3 of the first valve 29 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank. The fuel injection timing is controlled by applying an electric current to the valve.

<Structure explanation of the second booster circuit 55>
On the other hand, 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, which is higher than the power supply voltage VB, to the second valve drive units 58 and 59. To do.

As shown in FIG. 6, the second booster circuit 55 includes a coil 71, an n-channel type MOSFET 72 as a boost switch or a transistor, a resistor 73, a diode 74, and a charging capacitor 75. A coil 71, a drain / source of an n-channel 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 power supply node N0, and a charging capacitor 75 is connected between the power supply node N0 and the ground node. The power supply node N0 indicates a node that outputs the second boost voltage Vboost2 from the second boost circuit 55.

Therefore, when the second control IC 53 controls the step-up by controlling 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 be charged with the second boost voltage Vboost2, which is higher than the power supply voltage VB. In the initial state, the second control IC 53 sets the target voltage of the second boost voltage Vboost2 to the full charge voltage Vm (see FIG. 15), controls the boost, and boosts the voltage until the full charge voltage Vm of the second boost voltage Vboost2 is reached. Control. The MOSFET 72 serves as a heat source for the second booster circuit 55.

In the above description, it has been explained that the configuration of the first booster circuit 54 is the same as the configuration of the second booster circuit 55, but the full charge voltage of the first booster voltage Vboost1 of the first booster circuit 54 and the second booster circuit It may be the same as or different from the full charge voltage Vm of the second boost voltage Vboost2 of 55.

As illustrated in FIG. 7, the second valve drive unit 58 mainly includes a discharge switch 81b1, a constant current switch 82b1, and selection switches 83b1 and 84b1, a current detection resistor 85b1, diodes 87b1 to 89b1, and a recovery switch. It is configured by combining 90b1. The discharge switch 81b1, the constant current switch 82b1, the selection switches 83b1, 84b1, and the recovery switch 90b1 are each composed of, for example, an n-channel type MOS transistor. The selection switches 83b1 and 84b1 correspond to the first switch, and the recovery switch 90b1 corresponds to the second switch. The discharge switch 81b1 indicates a discharge circuit mainly provided for energizing the peak current Ip at normal times. The constant current switch 82b1 and the diode 87b1 indicate a constant current circuit provided for normal constant current control.

The second valve drive unit 58 is a second solenoid 32_ # 1 (corresponding to the first solenoid) and 32_ # 4 (corresponding to the second solenoid) connected between the upstream terminals 2b1a and the downstream terminals 2b1b and 2b1c of the control device 2. The second valve 30 of the fuel injection devices 7 and 10 corresponding to the cylinders # 1 and # 4 of the first bank is driven by the power interruption. As a result, the second control IC 53 opens and closes and drives the second valve 30 for two cylinders by applying a current to the second solenoids 32_ # 1 and 32_ # 4 by using the second valve driving unit 58. The second control IC 53 controls the fuel injection rate related to each cylinder # 1 and # 4 by driving and controlling the second valve drive unit 58, and the second solenoids 32_ # 1 and 32_ when the common rail 5 is decompressed. The drive current of # 4 is controlled at the same time.

The second boost voltage Vboost2 of the second boost circuit 55 is input to the drain of the MOS transistor which is the input terminal of the discharge switch 81b1. The discharge switch 81b1 energizes the upstream terminal 2b1a of the control device 2 from the output terminal side with the second boost voltage Vboost2 input to the input terminal according to the control signal given from the second control IC 53 to the control terminal of the discharge switch 81b1. It is possible.

Between the input node of the power supply voltage VB and the upstream terminal 2b1a of the control device 2, the drain source of the MOS transistor constituting the constant current switch 82b1 and the anode cathode of the diode 87b1 are connected in series. Further, the diode 88b1 is connected in the opposite direction between the upstream terminal 2b1a of the control device 2 and the ground. The diodes 87b1 and 88b1 are provided to prevent energization from the upstream terminal 2b1a to the supply terminal side of the power supply voltage VB and from the upstream terminal 2b1a to the ground side, respectively.

Between the node N11 of the upstream terminal 2b1a of the control device 2 and the node N21 of the first downstream terminal 2b1b, a second solenoid 32_ # for driving the second valve 30 of the fuel injection device 7 related to the cylinder # 1. 1 is connected. The node N21 corresponds to the first energizing node provided on the opposite side of the node N11 with respect to the second solenoid 32_ # 1. The second solenoid 32_ # 1 opens the second valve 30 of the fuel injection device 7 when energized. When the second solenoid 32_ # 1 is de-energized, the second valve 30 is closed by the urging force of the second spring 34.

The recovery switch 90b1 is controlled to be turned on or off by the microcomputer 51 via the pre-driver 51a. Between the power supply node N0 of the second boost voltage Vboost2 of the second booster circuit 55 and the node N21 of the first downstream terminal 2b1b of the control device 2, there is a drain source of the MOS transistor constituting the recovery switch 90b1. It is connected.

The recovery switch 90b1 is provided to regenerate the stored energy based on the current flowing through the second solenoid 32 to the charging capacitor 75 of the second booster circuit 55. Further, the recovery switch 90b1 is provided to simultaneously energize the second solenoids 32_ # 1 and 32_ # 4 in a state of being connected in series when the internal pressure of the common rail 5 is reduced.

Between the node N11 of the upstream terminal 2b1a of the control device 2 and the node N31 of the second downstream terminal 2b1c, a second solenoid 32_ # 4 for driving the second valve 30 of the fuel injection device 10 of the cylinder # 4 is provided. It is connected. The second solenoids 32_ # 1 and 32_ # 4 are electrically and commonly connected by the common node N11. The node N31 corresponds to a second energizing node provided on the opposite side of the node N11 with respect to the second solenoid 32_ # 4. The second solenoid 32_ # 4 opens the second valve 30 of the fuel injection device 10 when energized, and closes the second valve 30 when the fuel injection device 10 is de-energized.

A diode 89b1 is forwardly connected between the node N31 of the second downstream terminal 2b1c of the control device 2 and the power supply node N0 of the second boost voltage Vboost2 of the second booster circuit 55. The diode 89b1 is provided to regenerate the stored energy based on the current flowing through the second solenoid 32_ # 4 to the charging capacitor 75 of the second booster circuit 55.

Between the node N21 of the first downstream terminal 2b1b of the control device 2 and the ground node, the drain / source of the MOS transistor constituting the selection switch 83b1 and the current detection resistor 85b1 are connected in series. Between the second downstream terminal 2b1c of the control device 2 and the ground node, the drain / source of the MOS transistor constituting the selection switch 84b1 and the current detection resistor 85b1 are connected in series.

The selection switches 83b1 and 84b1 are usually provided to select the fuel injection devices 7 and 10 for injecting fuel. Further, when the common rail 5 is controlled to reduce the pressure, the selection switch 84b1 is turned on while the selection switch 83b1 is held in the off state.

The current detection resistor 85b1 detects the current flowing through the second solenoid 32_ # 1 of the fuel injection device 7 while the selection switch 83b1 is turned on. This detected value is input to the second control IC 53. The current detection resistor 85b1 detects the current flowing through the second solenoid 32_ # 4 of the fuel injection device 10 while the selection switch 84b1 is turned on. This detected value is input to the second control IC 53.

The second control IC 53 controls the discharge switch 81b1, the constant current switch 82b1, and the selection switches 83b1 and 84b1 on and off based on the set value set by the microcomputer 51, the injection signal, and the detection current of the current detection resistor 85b1. .. Since the second valve drive unit 58 is configured in this way, the second control IC 53 can control the energization of the second solenoids 32_ # 1 and 32_ # 4 by using the second valve drive unit 58, respectively. The opening and closing of the second valve 30 of the fuel injection devices 7 and 10 of the cylinders # 1 and # 4 can be controlled.

When the second valve drive unit 59 drives the second valve 30 of the fuel injection devices 8 and 9 corresponding to the cylinders # 2 and # 3 of the second bank, the upstream terminal 2b2a and the downstream terminal 2b2b of the control device 2 and the downstream terminal 2b2b Energization control is performed on the second solenoids 32_ # 2 and 32_ # 3, which are connected to 2b2c, respectively. As a result, the second control IC 53 controls the fuel injection rate by energizing the second solenoids 32_ # 3 and 32_ # 2 using the second valve drive unit 59, or controls the fuel injection rate when the common rail 5 is decompressed. The drive currents of 32_ # 2 and 32_ # 3 are controlled at the same time.

Since the circuit configuration of the second valve drive unit 59 has the same configuration as that of the second valve drive unit 58 as illustrated in FIG. 7, the description will be omitted with reference numerals similar to the corresponding configurations. As illustrated in FIG. 7, the upstream terminals 2b1a, downstream terminals 2b1b and 2b1c of the second valve drive unit 58 correspond to the upstream terminals 2b2a, downstream terminals 2b2b and 2b2c of the second valve drive unit 59. The switches 81b1, 82b1, 83b1 and 84b1 configured in the second valve drive unit 58 correspond to the switches 81b2, 82b2, 83b2 and 84b2 of the second valve drive unit 59. The current detection resistor 85b1 of the second valve drive unit 58 corresponds to the current detection resistor 85b2 of the second valve drive unit 59.

The diodes 87b1, 88b1 and 89b1 of the second valve drive unit 58 correspond to the diodes 87b2, 88b2 and 89b2 of the second valve drive unit 59. Further, the nodes N11, N21, and N31 of the second valve drive unit 58 correspond to the nodes N12, N22, and N32 of the second valve drive unit 59.

<Explanation of basic injection control processing>
Next, the flow of the basic injection control process will be described. When the internal combustion engine 11 has four cylinders and four cycles, one cycle is within the range of the crank angle 180 ° CA of the front and rear crank angle signals based on the top dead center TDC, and single injection or multiple stages such as 3 times and 5 times. Make a jet.

When the control device 2 injects and controls fuel from the injection holes 47 of the fuel injection devices 7 to 10 into the cylinders # 1 to # 4 of the internal combustion engine 11, the microcomputer 51 corresponds to each fuel injection device 7 to 10. The injection start signal is output to the first control IC 52 and the second control IC 53.

In the following, a 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 / interruption of the first orifice 45a by energizing the first solenoid 31_ # 1 and driving the first valve 29. In parallel with the processing of the first control IC 52, the second control IC 53 uses the second valve drive unit 58 to energize the second solenoid 32_ # 1 to drive the second valve 30, thereby driving the second valve 30. Controls the communication / blocking of 41a.

FIG. 8 shows changes in the energizing current (valve drive current) flowing through the first solenoid 31_ # 1 and the second solenoid 32_ # 1. First, the first control IC 52 controls the discharge switch 81a1 and the constant current switch 82a1 on while controlling the selection switch 83a1 on.

When the discharge switch 81a1, the constant current switch 82a1 and the selection switch 83a1 are turned on, the first boost voltage Vboost1 of the charging capacitor 75 of the first boost circuit 54 is applied to the first solenoid 31_ # 1 to increase the energizing current. When the energizing current rises, the first control IC 52 turns off the constant current switch 82a1 at the timing when a certain threshold value is reached. After that, when the peak current Ip set in the microcomputer 51 is reached, the first control IC 52 detects the peak current Ip based on the voltage detected by the current detection resistor 85, and turns off the discharge switch 81a1. Then, the current decreases and reaches the pickup current Ipa.

When the first control IC 52 detects that the current has reached the pickup current Ipa, the first control IC 52 holds the pickup current Ipa by controlling the constant current switch 82a1 on and off. The pickup current Ipa is set lower than the peak current Ip, and is a current generated by using the power supply voltage VB without using the first boost voltage Vboost1 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 current is further reduced from the pickup current Ipa to maintain a predetermined constant current Ipb larger than 0. The current switch 82a1 is controlled to be turned on and off. This predetermined constant current Ipb is set to be lower than the pickup current Ipa, and is a current generated by using the power supply voltage VB without using the first boost voltage Vboost1 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 82a1 and the selection switch 83a1 are turned off to reduce the current.

On the other hand, when the second control IC 53 receives the injection start signal, the second control IC 53 controls each switch 81b1 to 83b1 on / off. As shown in the energizing current of the second solenoid 32_ # 1 related to the injection M2 of FIG. 8, the second control IC 53 controls the energizing current of the second solenoid 32_ # 1 to the peak current Ip2, and then uses the peak current Ip2. The low pickup current Ipa2 is controlled for the command period Tp2, and then a predetermined constant current Ipb2 lower than the pickup current Ipa2 is controlled.

At this time, first, the second control IC 53 energizes the second solenoid 32 with the peak current Ip2 by using the second boost voltage Vboost2 of the second booster circuit 55 by turning on the discharge switch 81b1. After that, the second control IC 53 energizes the pickup current Ipa2 lower than the peak current Ip2 by controlling the constant current switch 82b1 on / off while the discharge switch 81b1 is off-controlled, and then the constant current Ipb2 lower than the pickup current Ipa2. Energizes the second solenoid 32. The pickup current Ipa2 and the constant current Ipb2 are generated by using the power supply voltage VB without using the second boost voltage Vboost2 of the second booster circuit 55.

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, It is set independently of the constant current Ipb2). Further, the microcomputer 51 also independently sets the command periods Tp1 and Tp2 of these current set values according to the characteristics of the first valve 29 and the second valve 30.

The microcomputer 51 sets the on / off control timing of the switches 81b1 to 83b1 by the second control IC 53 to be the same as or different from the on / off control timing of the switches 81a1 to 83a1 by the first control IC 52. To do. As a result, the microcomputer 51 can adjust the opening / closing control timing of the first valve 29 and the second valve 30. 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.

<Series connection control>
Hereinafter, processing 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. 9 to 11.
Normally, the microcomputer 51 confirms the state of the internal pressure of the common rail 5 by the pressure sensor 14 or the built-in pressure sensors 7a to 10a of each fuel injection device 7 to 10 in S1 of FIG. 9, and in S2. It is determined whether or not the pressure state mode (normal or abnormally high pressure state) has changed from the previous time. If the microcomputer 51 determines in S3 that the internal pressure of the common rail 5 has recovered from the abnormally high voltage state, the microcomputer 51 sets the set value of the energizing current of the second solenoid 32 during normal injection control in the memory in S5 and performs the second control. Output to IC53. For example, when the injection control of five-stage injection is executed during one cycle period, the microcomputer 51 stores the energization current of the second solenoid 32 related to the injection M2 with respect to the fuel injection device (for example, 7) as shown in FIG. Is set to and output to the second control IC 53. In this case, the second control IC 53 executes the energization control of the second solenoid 32 as usual.

On the other hand, the microcomputer 51 is abnormal when the mode of the pressure state has changed from the previous time in S2 of FIG. It is determined that the pressure is high, and the energization condition of the second solenoid 32 that drives the second valve 30 at the time of abnormality is set in S4. Output to. At the time of abnormal high pressure, as shown in FIG. 11, the microcomputer 51 issues a decompression command for a relatively long time as compared with the case of normal control.

At this time, first, the second control IC 53 sets the set value of the peak current Ip2 to 0A, sets the set value of the pickup current Ipa2 to 0A, and further sets the set value of the constant current Ipb2 to 0A. Then, the second control IC 53 turns off the discharge switches 81b1 and 81b2 and the constant current switches 82b1 and 82b2 so that the current exceeding the set value does not flow. As a result, the operation corresponding to the parallel connection drive circuit by the discharge switches 81b1 and 81b2 and the constant current switches 82b1 and 82b2 can be kept in an invalid state that is always off.

Next, the microcomputer 51 and the second control IC 53 use the second valve drive units 58 and 59 for the two cylinders to secure the reduced pressure flow rate, and the second solenoids 32_ # 1, 32_ for the two cylinders in the first bank. The target second valve 30 is opened by controlling # 4 to energize the constant current Ipb31. At the same time, the microcomputer 51 and the second control IC 53 use the second valve drive units 58 and 59 to energize the second solenoids 32_ # 2 and 32_ # 3 for the two cylinders of the second bank with a constant current Ipb32. By controlling, the target second valve 30 is opened. That is, the microcomputer 51 and the second control IC 53 control the second valves 30 of the fuel injection devices 7 to 10 for a total of four cylinders to open at the same time, so that the internal pressure of the common rail 5 can be quickly reduced in the rail depressurization mode described above. Decrease.

<Detailed explanation of energization control of constant current Ipb31 to the second solenoids 32_ # 1 and 32_ # 4>
As shown in FIG. 12, the flow of the current Ib1 is shown, the second control IC 53 turns off the selection switch 83b1 and turns on the selection switch 84b1, and the microcomputer 51 turns on the recovery switch 90b1 via the pre-driver 51a. By off-control, the second solenoids 32_ # 1 and 32_ # 4 are driven in a state of being connected in series via the common node N11.

More specifically, as shown in FIG. 13, the microcomputer 51 measures the on-control timing and the off-control timing using the timer from the timing of outputting the decompression command, and the recovery switch 90b1 via the pre-driver 51a. On / off control. When the recovery switch 90b1 is turned off, a reflux current Ib12 flows as illustrated in FIG. At this time, based on the stored energy of the second solenoids 32_ # 1 and 32_ # 4, the reflux current Ib12 flows through the body diode of the selection switch 83b1, the second solenoids 32_ # 1, 32_ # 4, and the selection switch 84b1.

While the second control IC 53 turns on the selection switch 84b1, the microcomputer 51 repeats the on / off control of the recovery switch 90b1 via the pre-driver 51a to determine the energizing currents of the second solenoids 32_ # 1 and 32_ # 4. It can be controlled within a predetermined range above and below the current Ipb31. As shown in FIG. 13, the lower limit permissible fluctuation value of the constant current Ipb31 is set to a value larger than the minimum guaranteed current threshold Isb1 required for holding the valve open of the second valve 30, whereby the cylinder of the first bank The second valve 30 of the fuel injection devices 7 and 10 according to # 1 and # 4 can be reliably opened and held.

<Detailed explanation of energization control of constant current Ipb32 to the second solenoids 32_ # 2 and 32_ # 3>
As shown in FIG. 12, the flow of the current Ib2 at the time of depressurization is shown. At the same time as described above, the second control IC 53 controls the selection switch 84b2 on while controlling the selection switch 83b2 off, and the microcomputer 51 controls the selection switch 84b2 on via the predriver 51a. By controlling the recovery switch 90b2 on and off, the second solenoids 32_ # 2 and 32_ # 3 are driven in a state of being connected in series via the common node N11.

More specifically, as shown in FIG. 13, the microcomputer 51 measures the on-control timing and the off-control timing using the timer from the timing of outputting the decompression command, and the recovery switch 90b2 via the pre-driver 51a. On / off control. When the recovery switch 90b2 is turned off, a reflux current Ib22 flows as illustrated in FIG. At this time, based on the stored energy of the second solenoids 32_ # 2 and 32_ # 3, the reflux current Ib22 flows through the body diode of the selection switch 83b2, the second solenoids 32_ # 2, 32_ # 3, and the selection switch 84b2.

While the second control IC 53 turns on the selection switch 84b2, the microcomputer 51 repeats the on / off control of the recovery switch 90b2 via the pre-driver 51a to generate the energizing currents of the second solenoids 32_ # 2 and 32_ # 3. It can be controlled within a predetermined range above and below the constant current Ipb32. As shown in FIG. 13, the lower limit permissible fluctuation value of the constant current Ipb32 is set to a value larger than the minimum guaranteed current threshold Isb2 required for holding the valve open of the second valve 30, whereby the cylinder of the second bank The second valve 30 of the fuel injection devices 8 and 9 according to # 2 and # 3 can be reliably opened and held.

Therefore, when reducing the internal pressure of the common rail 5, the microcomputer 51 controls the recovery switches 90b1 and 90b2 on and off via the pre-driver 51a while the second control IC 53 turns on the selection switches 84b1 and 84b2. The second solenoids 32_ # 1 ... 32_ # 4 can be energized while the constant current switch 82 and the discharge switch 81 are held in the off state. As a result, the second valve 30 of each fuel injection device 7 to 10 can be reliably opened and held.

In the above description, the pressure is reduced by opening the second valves 30 of the fuel injection devices 7 to 10 for four cylinders at the same time, but the second valves of the fuel injection devices 7 and 10 of the first bank for two cylinders are shown. It may be applied to a mode in which only 30 or only the second valve 30 of the fuel injection devices 8 and 9 of the second bank for two cylinders is opened.

<Summary of this embodiment>
As described above, according to the present embodiment, the second control IC 53 has the second solenoids 32_ # 1 and 32_ between the power supply node N0 and the ground node to which the boosted power of the second booster circuit 55 is supplied. In a state where # 4 is connected in series via the common node N11, the microcomputer 51 controls the recovery switch 90b1 on and off via the predriver 51a while controlling the selection switch 84b1 on. Thereby, the current can be controlled while passing the same current through the second solenoids 32_ # 1 and 32_ # 4 based on the boosted power supply by the second booster circuit 55. Properly maintain the valve opening holding current of the second valve 30 without significantly increasing the supply current to the two second solenoids 32_ # 1 and 32_ # 4 for driving the second valve 30 for two cylinders. be able to.

In this embodiment, the recovery switch 90b1 is connected between the node N21 and the power supply node N0, but the second control IC 53 holds the selection switch 84b1 connected between the node N31 and the ground node in the ON state. The microcomputer 51 controls the recovery switch 90b1 on / off via the pre-driver 51a. Therefore, the series connection control can be easily realized without significantly modifying the conventional control method in which the second control IC 53 executes the injection rate control while the selection switch 84b1 is on-controlled.

In addition, conversely, the same series connection control can be executed even if the second control IC 53 controls the selection switch 84b1 on / off while the microcomputer 51 holds the recovery switch 90b1 in the on state via the pre-driver 51a.

In this embodiment, the recovery switch 90b2 is connected between the node N22 and the power supply node N0, but the second control IC 53 holds the selection switch 84b2 connected between the node N32 and the ground node in the ON state. The microcomputer 51 controls the recovery switch 90b2 on / off via the pre-driver 51a. Therefore, series connection control can be easily realized without significantly modifying the conventional control method in which the second control IC 53 executes the injection rate control while the selection switch 84b2 is on-controlled.

On the contrary, even if the second control IC 53 controls the selection switch 84b2 on and off while the microcomputer 51 controls the recovery switch 90b2 on and off via the pre-driver 51a, the same series connection control as described above can be executed.

<Additional explanation of technical significance and effects according to the first embodiment>
Hereinafter, the technical significance and effects of the present embodiment will be additionally described together with Comparative Examples A1 and A2.
FIG. 14 shows a series connection control of the first bank of the present embodiment (when two solenoids 32_ # 1 and 32_ # 4 are energized in a state of being connected in series) and Comparative Example A1 (one solenoid 32_ # 1 is energized). A part of the current waveform comparing the three types of Comparative Example A2 (when two solenoids 32_ # 1 and 32_ # 4 are energized in a state of being connected in parallel) is shown in the figure.

For example, as in Comparative Example A1, the second control IC 53 turns on and off the constant current switch 82b1 while turning on the selection switch 83b1 to energize only one solenoid 32_ # 1 and control the pressure reduction. You can also. In this case, the second control IC 53 can control the depressurization by energizing the current required to hold the second valve 30 of the fuel injection device 7 open. However, since only the second valve 30 of the fuel injection device 7 for one cylinder can be opened, the decompression flow rate cannot be increased.

In order to increase the depressurized flow rate, the second control IC 53 controls both the selection switches 83b1 and 84b1 of the first bank on and off while controlling the constant current switch 82b1 on and off, so that the two second solenoids 32_ # It is also possible to control in a state where 1 and 32_ # 4 are connected in parallel.

However, as shown in the current waveform in Comparative Example A2, the current that energizes each of the second solenoids 32_ # 1 and 32_ # 4 is required to be doubled in total in principle, so that the current is required when driving for a long time. It is necessary to prepare and connect a highly resistant element again. Further, the combined inductance value of the solenoids 32_ # 1 and 32_ # 4 connected in parallel is halved as compared with the case of Comparative Example A1. Since the current is doubled and the switching frequency is doubled, the emission may be deteriorated.

Further, when the impedance of the energization path of the second solenoids 32_ # 1 and 32_ # 4 varies, there is a possibility that a large amount of current flows to one solenoid (for example, 32_ # 1) having a current and the current is biased. Then, even if the other solenoid (for example, 32_ # 4) drives the second valve 30, there is a possibility that the second valve 30 cannot be opened.

With respect to this Comparative Example A2, according to the control configuration for two cylinders of the first bank according to the present embodiment, the second control IC 53 controls the solenoids 32_ # 1 and 32_ # 4 in a state of being connected in series. The current flowing through one of the solenoids (for example, 32_ # 1) is not biased, and the second valve 30 driven by the second solenoids 32_ # 1 and 32_ # 4 can be opened with high reliability.
Further, the combined inductance of the solenoids 32_ # 1 and 32_ # 4 is twice that of Comparative Example A1, and the slope of the current is halved as compared with Comparative Example A1. Therefore, since the switching frequency for adjusting to the target current I0 is halved as compared with Comparative Example A1, there is no adverse effect on emissions.

According to the configuration according to the present embodiment, the second control IC 53 can execute the series connection control while suppressing the drive currents of the second solenoids 32_ # 1 and 32_ # 4. According to the configuration according to the present embodiment, the second control IC 53 can execute the series connection control while suppressing the bias of the drive currents of the second solenoids 32_ # 1 and 32_ # 4. According to the configuration according to the present embodiment, the second control IC 53 can execute the series connection control while suppressing the switching frequency related to the switching control of the second solenoids 32_ # 1 and 32_ # 4.

Further, the second control IC 53 controls the selection switch 84b1 by keeping the operations of the discharge switch 81b1 and the constant current switch 82b1 constituting the parallel connection drive circuit in the disabled state at all times during the depressurization control, and also controls the microcomputer 51. Controls the recovery switch 90b1 via the pre-driver 51a to simultaneously control the drive currents of the solenoids 32_ # 1 and 32_ # 4 of the first bank. Therefore, thermal stress is not applied to the elements of the control path during normal injection control (for example, constant current switches 82b1 and 82b2, diodes 87b1 and 87b2). Although the control of the first bank has been described, the same effect can be obtained with the control of the second bank.

For example, as shown in FIG. 11, even if a decompression command is issued during most of one cycle and the energization time of the second solenoids 32_ # 1 ... 32_ # 4 per unit time increases, constant current control is performed. No thermal stress is applied to the elements intervening in the path.

(Second Embodiment)
FIG. 15 shows an additional explanatory diagram of the second embodiment. The second control IC 53 boost-controls the second boost voltage Vboost2 of the second booster circuit 55 up to the full charge voltage Vm during normal operation. During injection control or depressurization control, the second boost voltage Vboost2 of the second boost circuit 55 is lowered by releasing the accumulated charge charged in the charging capacitor 75. When the second boost voltage Vboost2 drops to a predetermined boost start threshold value Vk, the second control IC 53 raises the second boost voltage Vboost2 of the power supply node N0 by controlling the MOSFET 72 of the second boost circuit 55 on and off. Control. At this time, the second control IC 53 continues to control the MOSFET 72 on and off until the second boost voltage Vboost2 rises to the full charge voltage Vm.

For example, when the second control IC 53 controls the second boost voltage Vboost2 of the second booster circuit 55 to energize the second solenoids 32_ # 1 and 32_4 for a long time during decompression control, the second boost voltage Vboost2 is boosted. Even if it is controlled, the full charge voltage Vm is not reached, and the second control IC 53 may repeat the on / off control of the MOSFET 72 for a long time. In this case, the amount of heat generated by the MOSFET 72 of the second booster circuit 55 may be significantly increased. When there is a concern that the amount of heat generated by the MOSFE 72 will increase, the second control IC 53 may be set to stop driving the second booster circuit 55 before the timing t0 when the series connection control is started to be executed. That is, the second control IC 53 may be controlled so as to keep the MOSFET 72 off. See t0, the start timing of the series connection control shown in FIG.

In this case, after the start timing t0 of the series connection control, the second boost voltage Vboost2 of the second booster circuit 55 drops from the full charge voltage Vm as the charge charge of the charging capacitor 75 is released. However, as shown in FIG. 6, since the power supply voltage VB is supplied to one end of the coil 71, even if the boost voltage Vboost2 drops, as shown in FIG. 15, a voltage at least equal to or higher than the power supply voltage VB is applied to the coil 71. Can be supplied to the power supply node N0 through the diode 74. Therefore, the second control IC 53 continues to drive the second solenoids 32_ # 1 ... 32_ # 4 by using the supply voltage of the power supply node N0 by the path of the currents Ib1, Ib12, Ib2, and Ib22 shown in FIG. Can be done. As a result, the second control IC 53 can suppress the power consumption of the second booster circuit 55 by holding the MOSFET 72 in the off state.

As described above, according to the present embodiment, the second control IC 53 passes through the second booster circuit 55 by setting the drive of the second booster circuit 55 to stop before the timing t0 when the series connection control is executed. A voltage at least equal to or higher than the power supply voltage VB is supplied to the power supply node N0 to execute series connection control. As a result, the power consumption of the second booster circuit 55 can be suppressed. Moreover, the energization time of the second solenoids 32_ # 1 and 32_ # 4 can be secured for a long time, and the decompression control of the internal pressure of the common rail 5 can be continued for a long time.

(Third Embodiment)
16 to 18 show additional explanatory views of the third embodiment.
<Parallel connection control>
As shown in FIG. 16 for the paths of the currents Ic1, Ic12, Ic1a, and Ic12a, the second valve drive units 58 and 59 are energized with the solenoids 32_ # 1 and 32_ # 4 for two cylinders connected in parallel. It is also possible to reduce the internal pressure of the common rail 5. At this time, as shown in FIG. 17, the second control IC 53 uses the second valve drive units 58 and 59 to control the selection switch 84b1, the discharge switch 81b1, and the constant current switch 82b1 on / off.

When the second control IC 53 receives the decompression command, as shown in FIG. 17, after controlling the total energizing current of the second solenoids 32_ # 1 and 32_ # 4 to the total peak current Ip41, the predetermined value is lower than the total peak current Ip41. The total constant current Ipb41 is controlled.

At this time, first, the second control IC 53 uses the second boost voltage Vboost2 of the second booster circuit 55 by turning on the selection switches 83b1 and 84b1 and turning on the discharge switch 81b1, so that the second solenoid 32_ # 1 and Energize 32_ # 4. The second control IC 53 turns off the discharge switch 81b1 when the current detection resistor 85b1 detects that the total energizing current has reached the total peak current Ip41. After that, the second control IC 53 energizes the second solenoids 32_ # 1 and 32_ # 4 with a total constant current Ipb41 lower than the total peak current Ip41 by controlling the constant current switch 82b1 on and off. At this time, the second control IC 53 detects the current by the current detection resistor 85b1 and adjusts it within the range of the upper limit value and the lower limit value of the total constant current Ipb41.

The total constant current Ipb41 can be generated by using the power supply voltage VB without using the second boost voltage Vboost2 of the second booster circuit 55. As a result, the second control IC 53 can simultaneously energize both the second solenoids 32_ # 1 and 32_ # 4, and can perform decompression control while increasing the decompression flow rate as in the above-described embodiment. Although the first bank has been described, the description will be omitted because the same applies to the second bank. In FIG. 17, the total peak current Ip42 shown for the second bank corresponds to the total peak current Ip41 for the first bank. Further, the total constant current Ipb42 shown for the second bank is shown corresponding to the total constant current Ipb41 of the first bank.

<Series-Parallel mixing control>
Hereinafter, a control method in which the control method (series connection control) described in the first embodiment and the control method (parallel connection control) described in the third embodiment will be described will be described.

When the second control IC 53 receives the decompression command at the timing t10 of FIG. 18, the second control IC 53 executes the series connection control described in the first embodiment. As illustrated in FIG. 18, when the second solenoids 32_ # 1 and 32_ # 4 are energized, the boost voltage Vboost2 of the second booster circuit 55 drops to the boost start threshold value Vk. Then, the second control IC 53 starts boost control at the timing t11 of FIG. 18 and controls the MOSFET 72 on / off.

When the temperature of the MOSFET 72 rises due to the switching control of the MOSFET 72, the temperature detected by the temperature sensor 72 also gradually rises. For example, when the second control IC 53 ends the series connection control during one cycle period, the charging capacitor 75 of the second booster circuit 55 stops consuming the charging charge at the timing t12. Therefore, the second control IC 53 continues the switching control of the MOSFET 72 (the boost control of the second boost circuit 55), so that the second boost voltage Vboost2 rises to the full charge voltage Vm at the timing t13. As a result, the second control IC 53 stops the boost control of the second boost circuit 55. When the second control IC 53 stops the boost control of the second booster circuit 55, the ambient temperature of the MOSFET 72 begins to decrease.

Further, when the series connection control is continued in the second control IC 53 in the cycle period after the next time, the charge charge of the charge capacitor 75 of the second booster circuit 55 is consumed again. Therefore, when the second control IC 53 detects that the boost voltage Vboost2 has dropped to the boost start threshold value Vk at the timing t14 of FIG. 18, the boost control of the second boost circuit 55 is started and the MOSFET 72 is turned on / off. ..

At this time, when the second control IC 53 repeats the boost control using the MOSFET 72 many times, the temperature of the MOSFET 72 gradually rises and approaches the rated temperature Temp of the MOSFET 72. Therefore, the microcomputer 51 defines in advance the limit energization time T1 for continuing the series connection control so as not to exceed the rated temperature Temp of the MOSFET 72, and holds it in the internal memory.

The microcomputer 51 measures the time from the timing t10 using the internal timer, and when the limit energization time T1 elapses from the start timing t10 of the decompression control, the execution of the series connection control to the second control IC 53 is stopped at the timing t15. , Command to execute parallel connection control. As a result, the second control IC 53 executes the parallel connection control described above.

As shown in the timings t15 to t22 of FIG. 18, the second control IC 53 executes parallel connection control. As described above, the time required for the second boost voltage Vboost2 to be used when the second control IC 53 executes the parallel connection control is only the time t16 to t17, t18 to t19, and t20 to t21 required for energizing the total peak current Ip41. is there. Therefore, for a relatively long period of time other than that, t17 to t18, t19 to t20, and t21 to t22, the second control IC 53 can execute parallel connection control without using the second boost voltage Vboost2 of the second boost circuit 55.

Therefore, the time ratio for boosting the boost voltage Vboost2 during the parallel connection control is smaller than the time ratio for boosting the boost voltage Vboost2 during the series connection control. Therefore, the drive time of the MOSFET 72 can be reduced by the second control IC 53 executing the parallel connection control with less power consumption by the second booster circuit 55 than the series connection control, and the temperature of the MOSFET 72 can be gradually lowered. it can.

Further, it is preferable to set in advance the return time T2 of the series connection control, which is the limit time for continuing the parallel connection control. The microcomputer 51 measures the time from the start timing t15 of the parallel connection control using the internal timer, and when the return time T2 of the series connection control elapses, the microcomputer 51 executes the series connection control to the second control IC 53 at the timing t22. Command. In this way, the second control IC 53 can repeatedly execute the series connection control and the parallel connection control.

As a result, when the internal pressure of the common rail 5 is reduced and controlled, the element used for series connection control (for example, recovery switch 90b1) and the element used for parallel connection control (for example, discharge switch 81b1, constant current switch 82b1, diode 87b1). ), And heat stress can be appropriately distributed to each path.

As described above, according to the present embodiment, the second control IC 53 executes the series connection control to simultaneously control the drive currents of the second solenoids 32_ # 1 and 32_ # 4, and the limit energization time. After T1, the second solenoids 32_ # 1 and 32_ # 4 are connected in parallel, and the second booster circuit 55 switches to execute parallel connection control with less power consumption.

The second control IC 53 can reduce the driving time per unit time of the MOSFET 72 of the second booster circuit 55. As a result, the energization time of the second solenoids 32_ # 1 and 32_ # 4 can be secured for a long time while maintaining the temperature condition of the rated temperature Temp of the MOSFET 72, and the decompression control of the internal pressure of the common rail 5 can be continued for a long time.

(Fourth Embodiment)
19 and 20 show additional explanatory views of the fourth embodiment. In the fourth embodiment, the same parts as those in the third embodiment are designated by the same reference numerals to describe different parts. As illustrated in FIG. 19, a temperature sensor 91 as a temperature detection unit is arranged in the vicinity of the MOSFET 72, and the microcomputer 51 can acquire the temperature of the MOSFET 72 by the temperature sensor 91.

At the timing t15a of FIG. 20, when the detection temperature of the temperature sensor 91 exceeds the upper limit threshold temperature Tu obtained by subtracting the predetermined margin temperature from the rated temperature Temp, the series connection control is stopped at the second control IC 53 and the parallel connection control is executed. Command to do. The second control IC 53 executes the parallel connection control described above.

As shown in the timings t15a to t22 of FIG. 20, the time ratio for boosting the boost voltage Vboost2 during the parallel connection control is smaller than the time ratio for boosting the boost voltage Vboost2 during the series connection control. Therefore, by executing the parallel connection control in which the second booster circuit 55 consumes less power than the series connection control, the second control IC 53 can reduce the drive time of the MOSFET 72 and gradually lower the temperature of the MOSFET 72. it can.

Further, when the microcomputer 51 detects that the temperature has dropped to the lower limit threshold temperature Td due to the detection temperature of the temperature sensor 91, the microcomputer 51 instructs the second control IC 53 to execute the series connection control. In this way, the second control IC 53 may repeatedly execute the series connection control and the parallel connection control.

As a result, when the internal pressure of the common rail 5 is reduced and controlled, an element used for series connection control (for example, recovery switch 90b1) and an element used for normal parallel connection control (for example, discharge switch 81b1, constant current switch 82b1, diode). The heat can be dispersed to 87b1), and the heat stress can be appropriately distributed to each path.

As described above, according to the present embodiment, the second control IC 53 is a temperature sensor when the series connection control is executed to simultaneously control the drive currents of the second solenoids 32_ # 1 and 32_ # 4. When the temperature detected by 91 exceeds the upper limit threshold temperature Tu, the parallel connection control is executed with the second solenoids 32_ # 1 and 32_ # 4 connected in parallel.

The second control IC 53 can reduce the driving time per unit time of the MOSFET 72 constituting the second booster circuit 55. As a result, the energization time of the second solenoids 32_ # 1 and 32_ # 4 can be secured for a long time while maintaining the temperature condition of the rated temperature Temp of the MOSFET 72, and the decompression control of the internal pressure of the common rail 5 can be continued for a long time.

(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.

In the above-described embodiment, the fuel injection device 7 to 10 is configured to return the fuel to the fuel tank 12 through the low-pressure pipe 38, but the common rail 5 may be provided with a pressure reducing valve in combination to reduce the pressure from the pressure reducing valve. good. 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", 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 mode in which the control circuit 50 and the second control IC 53 execute the decompression control with the second solenoids 32_ # 1, 32_ # 4 and the second solenoids 32_ # 1 and 32_ # 4 connected in series has been described. It is not limited to control, but can also be applied when various controls are executed in a series connected state.

Although the "second switch" has shown an example corresponding to the recovery switches 90b1 and 90b2, a recovery switch may be provided as the second switch instead of the diodes 89b1 and 89b2 shown in FIG. That is, although the embodiment in which the recovery switch 90b1 is provided between the node N21 and the node N0 and the recovery switch 90b2 is provided between the node N22 and the node N0, the recovery switch is provided between the node N31 and the node N0. It may be separately provided as a switch, or a recovery switch may be separately provided as a second switch between the node N32 and the node N0.

Although the microcomputer 51 has shown a form in which the recovery switches 90b1 and 90b2 are on / off controlled via the pre-driver 51a, the present invention is not limited to this. The second control IC 53 may be configured by incorporating the control contents of the recovery switches 90b1 and 90b2 by the microcomputer 51 and the pre-driver 51a.

For example, if the second control IC 53 can execute on / off control of the recovery switches 90b1 and 90b2, the peak current energized in the second solenoids 32_ # 1 and 32_ # 4 at the time of series connection control, and It is also possible to control the series connection while detecting the lower limit value and the upper limit value of the constant current by the current detection resistor 85b1, respectively.
When the microcomputer 51 and the second control IC 53 perform series connection control, the voltage value of the boosted voltage Vboost2 is detected, and the second solenoids 32_ # 1 and 32_ # 4 are energized according to the boosted voltage Vboost2 using the detected voltage as a parameter. The period and the off period may be changed and controlled.

The microcomputer 51, 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 the first control IC 52 and the second control IC 53 may be configured. The 2 control IC 53 may be integrated with the microcomputer 51. Although the form in which an n-channel type MOS transistor is used as various switches is shown, the present invention is not limited to this, and various switching elements can be applied.

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. The internal combustion engine 11 can be applied even if it has two cylinders or six cylinders or more.

The configurations of the respective embodiments 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 without departing 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 the embodiments and structures. The present disclosure also includes various modifications and modifications within an equal range. In addition, various combinations and forms, as well as other combinations and forms including one element, more, or less, are also within the scope of the present disclosure.

In the drawing, 2 is a control device (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, and 30 is a second valve (target). Valve, pressure reducing valve), 31 is the first solenoid, 32_ # 1, 32_ # 2 is the second solenoid (first solenoid), 32_ # 4, 32_ # 3 is the second solenoid (second solenoid), 50 is the control circuit. , 55 indicate a second booster circuit (boost circuit), 83b1, 84b1, 83b2, 84b2 indicate a selection switch (first switch), and 90b1, 90b2 indicate a recovery switch (second switch).

Claims (8)

A control device that controls at least two cylinders of a fuel injection device (7 to 10) that has two valves built-in and is configured to be able to independently drive one of the two valves, the target valve (30). (2)
One ends of the first solenoids (32_ # 1, 32_ # 2) and the second solenoids (32_ # 4, 32_ # 3) that drive the target valves of the fuel injection device for the two cylinders are electrically connected in common. Common nodes (N11, N12) and
The first energizing nodes (N21, N22) provided on the opposite side of the common node with respect to the first solenoid, and
The second energizing nodes (N31, N32) provided on the opposite side of the common node with respect to the second solenoid, and
A first switch (83b1, 84b1, 83b2, 84b2) connected to either the first energizing node and the ground node or between the second energizing node and the ground node.
A booster circuit (55) that supplies boosted power that boosts the power supply voltage to the power supply node (N0),
A second switch (90b1, 90b2) connected between at least one of the first energizing node or the second energizing node and the power supply node, and
With the first solenoid and the second solenoid connected in series between the power supply node and the ground node with the common node interposed therebetween, one of the first switch and the second switch is turned on. A control circuit (50) that executes series connection control that simultaneously controls the drive currents of the first solenoid and the second solenoid by controlling the other on and off while controlling.
A control device comprising. A parallel connection drive circuit (81b1, 82b1, 81b2, 82b2) that enables driving of the first solenoid and the second solenoid in a state of being connected in parallel through the common node is further provided.
The control device according to claim 1, wherein the control circuit executes the series connection control by controlling the first switch and the second switch while keeping the operation of the parallel connection drive circuit always off in an invalid state. .. When the second switch is connected between the first energizing node and the power supply node,
The control device according to claim 1 or 2, wherein the control circuit controls the on / off of the second switch while keeping the first switch connected between the second energizing node and the ground node on-controlled. .. When the second switch is connected between the first energizing node and the power supply node,
The control device according to claim 1 or 2, wherein the control circuit controls on / off of the first switch connected between the second energizing node and the ground node while the second switch is on-controlled. .. A parallel connection drive circuit (81b1, 82b1, 81b2, 82b2) that enables driving of the first solenoid and the second solenoid in a state of being connected in parallel through the common node is provided.
The control circuit is configured to be capable of executing parallel connection control using the parallel connection drive circuit, which consumes less power by the booster circuit than the series connection control.
When the limit energization time (T1) elapses when the control circuit executes the series connection control and simultaneously controls the drive currents of the first solenoid and the second solenoid, the first solenoid and the first solenoid. (Ii) The control device according to claim 1 or 2, wherein the solenoids are switched so as to execute the parallel connection control in a state where the solenoids are connected in parallel. A parallel connection drive circuit (81b1, 82b1, 81b2, 82b2) that enables the first solenoid and the second solenoid to be driven in parallel through the common node.
A temperature detection unit (91) that detects the temperature of the heat generation source (72) of the booster circuit, and
With more
The control circuit is configured to be capable of executing parallel connection control using the parallel connection drive circuit, which consumes less power by the booster circuit than the series connection control.
When the control circuit executes the series connection control and simultaneously controls the drive currents of the first solenoid and the second solenoid, the temperature detected by the temperature detection unit exceeds the upper limit threshold temperature (Tu). The control device according to claim 1 or 2, wherein the first solenoid and the second solenoid are switched so as to execute the parallel connection control in a state where the second solenoid is connected in parallel. The control circuit supplies a voltage at least equal to or higher than the power supply voltage to the power supply node through the booster circuit by setting the drive of the booster circuit to stop before the timing (t0) when the series connection control is started to be executed. The control device according to claim 1 or 2, wherein the series connection control is executed. The fuel injection device incorporates the two valves for controlling the fuel injection rate, and of the two valves, the pressure reducing valve (30), which is also used for depressurization, is driven as the target valve to reduce the oil pressure. It is configured so that it can be depressurized.
The control device according to any one of claims 1 to 7, which controls the pressure reducing valve of the fuel injection device (7 to 10) for at least two cylinders or more.

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