JP2005076510A - Fuel injection device and its control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve startability of an internal combustion engine using a fuel injection device having a pressure intensifier. <P>SOLUTION: A first accumulator 31 functions as a fuel supply source to a fuel sump 6, an injector control chamber 3 and a second cylinder chamber 35, and a second accumulator 32 functions as a fuel supply source to a first cylinder chamber 34 and a pressure intensifier control chamber 14. Volume of the second accumulator 32 is set larger than that of the first accumulator 31. A differential pressure generating valve 33 contains a valve for cutting off communication of the first accumulator 31 with the second accumulator 32 when fuel pressure inside the first accumulator 31 is below a predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection device and a control device therefor, and more particularly, to a device capable of further injecting and injecting fuel stored in a pressure accumulating chamber.

  An example of this type of fuel injection device is disclosed in Japanese Patent No. 2885076 (Patent Document 1). In Patent Document 1, there is provided a pressure increasing device that can further increase the pressure of fuel delivered from the pressure accumulating chamber by a pressure increasing piston. The pressure-increasing piston is pressurized by the fuel in the large oil chamber. By releasing the pressure in the middle oil chamber, the force by which the pressure-increasing piston pressurizes the fuel in the small oil chamber increases, and the injection pressure increases. By switching the supply / release of the pressure in the middle oil chamber with an electromagnetic valve, the fuel from the pressure accumulation chamber is directly sent to the injection valve for injection, and the fuel further increased by the pressure increase device is sent to the injection valve. Switching between high pressure injection and injection is possible. The pressure-increasing piston after the high-pressure injection is returned to the initial position by the spring force.

  Further, as other background art, the fuel injection devices of Patent Documents 2 and 3 are disclosed.

Japanese Patent No. 2885076 JP-A-8-277762 International Publication No. 02/14681 Pamphlet

  In the fuel injection device shown in Patent Document 1, since it is necessary to set the volume of the pressure accumulating chamber to be large in order to ensure the stability of the operation of the pressure increasing device, the pressure in the pressure accumulating chamber can be started at the time of starting the internal combustion engine. There is a problem that it is difficult to increase the pressure in a short time and the startability of the internal combustion engine is deteriorated. Since the operation of returning the pressure-increasing piston to the initial position after high-pressure injection is performed only by the spring force, it is difficult to return the pressure-increasing piston to the initial position in a short time, and high-pressure injection is performed during high-speed operation of the internal combustion engine. There is a problem that it is difficult to perform stably. Furthermore, since it is necessary to set the volume of the pressure accumulating chamber to be large as described above, there is a problem that it is difficult to depressurize the pressure accumulating chamber in a short time when it is necessary to depressurize the pressure accumulating chamber.

  An object of the present invention is to improve the startability of an internal combustion engine that uses a fuel injection device having a pressure boosting device. Another object of the present invention is to provide a fuel injection device and a control device for the fuel injection device that can stably operate the pressure booster even during high-speed operation of the internal combustion engine. Another object of the present invention is to provide a control device for a fuel injection device having a pressure increasing device capable of quickly reducing the pressure in the pressure accumulating chamber.

  The fuel injection device and the control device thereof according to the present invention employ the following means in order to achieve at least a part of the above object.

  The fuel injection device according to the present invention includes a pressure accumulating means for accumulating fuel supplied from a pump, and a pressure increasing piston that is pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber. The pressure piston pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber by increasing the control force that acts on the pressure-increasing piston, thereby accumulating in the fuel reservoir that communicates with the second cylinder chamber. A pressure increasing means for increasing the pressure of the fuel that has been stored, and an injection nozzle for injecting the fuel stored in the fuel reservoir by the operation of a needle, and the fuel stored in the pressure storing means is increased by the pressure increasing means. A fuel injection device capable of injecting under pressure, wherein the pressure accumulating means communicates with the second cylinder chamber and has a first accumulator chamber for accumulating fuel supplied from a pump and a volume from the first accumulator chamber. But When the pressure of the fuel in the first pressure accumulation chamber is below a predetermined value, the second pressure accumulation chamber communicates with the first cylinder chamber and accumulates fuel supplied from the first pressure accumulation chamber. And a shutoff valve that shuts off the supply of fuel to the second pressure accumulating chamber.

  In the present invention, as a pressure accumulating chamber for accumulating fuel, a first pressure accumulating chamber for fuel injection and a second pressure accumulating chamber for operating pressure increasing means are provided, and the volume of the first pressure accumulating chamber is the second. It is smaller than the volume of the accumulator. When starting the internal combustion engine, the supply of fuel from the first pressure accumulation chamber to the second pressure accumulation chamber is shut off by the shutoff valve, so that the fuel pressure in the first pressure accumulation chamber and the fuel reservoir is quickly increased. be able to. Therefore, according to the present invention, the startability of the internal combustion engine can be improved.

  The fuel injection device according to the present invention includes a pressure accumulating means for accumulating the fuel supplied from the pump, and a pressure increasing piston that is pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber, A fuel reservoir that communicates with the second cylinder chamber by increasing the force by which the pressure increasing piston pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber by changing the control force that acts on the pressure increasing piston. Pressure increasing means for increasing the pressure of the fuel stored in the fuel reservoir, and an injection nozzle for injecting the fuel stored in the fuel reservoir by the operation of a needle, and the pressure increasing means for increasing the pressure of the fuel stored in the pressure accumulating means The pressure-accumulating means communicates with the second cylinder chamber and accumulates fuel supplied from a pump, and the first cylinder. A first accumulator chamber that communicates with the chamber and accumulates fuel supplied from the first accumulator chamber, and the pressure of the fuel in the first accumulator chamber is higher than the pressure of the fuel in the second accumulator chamber. And a differential pressure generating valve that opens and closes between the first pressure accumulating chamber and the second pressure accumulating chamber.

  In the present invention, the differential pressure generating valve opens and closes the first accumulator chamber and the second accumulator chamber so that the fuel pressure in the first accumulator chamber is higher than the fuel pressure in the second accumulator chamber. . As a result, when the pressure increasing piston is returned to the initial position after the fuel is injected by increasing the pressure by the pressure increasing means, the pressure of the fuel in the second cylinder chamber can be made higher than before, so that the pressure increasing piston is initialized. The restoring force for returning to the position can be increased as compared with the prior art. Therefore, according to the present invention, the time required to return the pressure-increasing piston to the initial position can be shortened. Therefore, even during high-speed operation of the internal combustion engine, the operation of increasing and injecting fuel by the pressure-intensifying means is performed. It can be performed stably.

  In the fuel injection device according to the present invention, the differential pressure generating valve is configured to move from the first pressure accumulation chamber when the difference between the fuel pressure in the first pressure accumulation chamber and the fuel pressure in the second pressure accumulation chamber is equal to or less than a predetermined value. A valve that shuts off the supply of fuel to the second pressure accumulating chamber may be included. In the fuel injection device according to the present invention, the differential pressure generating valve has a first pressure accumulation chamber and a second pressure accumulation chamber when the pressure of the fuel in the second pressure accumulation chamber is larger than the pressure of the fuel in the first pressure accumulation chamber. A valve to be communicated may be included.

  The control device for a fuel injection device according to the present invention includes a pressure accumulating means for accumulating fuel supplied from a pump, and a pressure increasing piston pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber. The pressure increasing piston increases the force of pressurizing the fuel supplied from the pressure accumulating means to the second cylinder chamber by releasing the pressure in the control chamber, so that the pressure increasing piston is stored in the fuel reservoir communicating with the second cylinder chamber. Pressure increasing means for increasing the pressure of the fuel, switching means capable of switching between a first state in which the control pressure is supplied into the control chamber and a second state in which the pressure in the control chamber is released, and the fuel reservoir And switching the switching means from the first state to the second state and operating the needle for a fuel injection device including an injection nozzle for injecting the fuel stored in the nozzle by the operation of the needle By performing the control, the control device is capable of injecting the fuel accumulated in the pressure accumulating means by increasing the pressure by the pressure increasing means, and injecting the fuel by increasing the pressure by the pressure increasing means. Thereafter, when the switching means is switched from the second state to the first state to return the position of the pressure increasing piston, the needle is not operated so that the fuel pressure in the second cylinder chamber increases. The gist of the invention is to have control means for performing switching control for temporarily switching the switching means from the first state to the second state.

  In this invention, after the fuel is boosted by the pressure boosting means and injected, the needle is operated when the switching means is switched from the second state to the first state to return the position of the boosting piston that has moved. Instead, the switching means is temporarily switched from the first state to the second state. As a result, the pressure of the fuel in the second cylinder chamber increases, and the increased pressure in the second cylinder chamber and the pressure supplied to the control chamber can act as a restoring force of the pressure increasing piston. The return speed can be increased. Therefore, according to the present invention, the time required to return the pressure-increasing piston to the initial position can be shortened. Therefore, even during the high-speed operation of the internal combustion engine, the operation of increasing the fuel pressure by the pressure-intensifying means and injecting the fuel is performed. It can be performed stably.

  In the control device for the fuel injection device according to the present invention, the control means may perform the switching control when the rotational speed of the internal combustion engine into which the fuel is injected is a predetermined value or more. In the control device for a fuel injection device according to the present invention, the control means may perform the switching control when a required torque of an internal combustion engine into which fuel is injected is a predetermined value or more. In the control device for the fuel injection device according to the present invention, the control means performs the switching control when the fuel is boosted and injected by the pressure increasing means without performing the switching control for a predetermined cycle. It can also be done.

  The control device for a fuel injection device according to the present invention includes a pressure accumulating means for accumulating fuel supplied from a pump, and a pressure increasing piston pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber. The pressure increasing piston increases the force of pressurizing the fuel supplied from the pressure accumulating means to the second cylinder chamber by releasing the pressure in the control chamber, so that the pressure increasing piston is stored in the fuel reservoir communicating with the second cylinder chamber. A pressure increasing means for increasing the pressure of the fuel, a switching means capable of switching between a first state in which the control chamber and the pressure accumulating means are communicated, and a second state in which the pressure in the control chamber is released; Switching the switching means from the first state to the second state and operating the needle for a fuel injection device comprising an injection nozzle for injecting fuel stored in a fuel reservoir by operation of the needle The control device is capable of injecting the fuel accumulated in the pressure accumulating means by the pressure intensifying means, and injecting the fuel temporarily, without operating the needle. The gist of the invention is that it has control means for reducing the pressure of the fuel in the pressure accumulating means without injecting fuel by performing switching control for switching from the first state to the second state.

  In the present invention, the pressure of the fuel in the pressure accumulating means is decreased without injecting fuel by temporarily switching the switching means from the first state to the second state without operating the needle. The pressure of the fuel in the pressure accumulating means can be quickly reduced without using a pressure reducing valve.

  In the control device for the fuel injection device according to the present invention, the control means may perform the switching control repeatedly. In the control apparatus for a fuel injection device according to the present invention, the control means may perform the switching control while avoiding a fuel injection period in an operating state in which fuel is injected.

  In the control device for the fuel injection device according to the present invention, the control means may perform the switching control when the rotational deceleration of the internal combustion engine into which the fuel is injected is a predetermined value or more. In the control device for the fuel injection device according to the present invention, the control means may perform the switching control when the rate of decrease in the required torque of the internal combustion engine into which the fuel is injected is a predetermined value or more. . In the control device for the fuel injection device according to the present invention, the control means may perform the switching control when the pressure of the fuel in the pressure accumulating means is higher than a set pressure by a predetermined value or more. In the control device for the fuel injection device according to the present invention, the control means may perform the switching control when the fuel injection to the internal combustion engine is stopped. Here, the case of stopping the fuel injection to the internal combustion engine includes a case where fuel cut is temporarily performed during the operation of the internal combustion engine, and the case where the operation of the internal combustion engine is stopped.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

“First Embodiment”
FIG. 1 is a diagram showing an outline of the configuration of the fuel injection device according to the first embodiment of the present invention. The fuel injection device of this embodiment is applied to, for example, a compression ignition internal combustion engine, and includes a fuel pressurizing pump 1, a first pressure accumulation chamber 31, a second pressure accumulation chamber 32, a differential pressure generating valve 33, and An injector 100 is provided. The injector 100 is provided corresponding to each cylinder, and includes a nozzle 5, an injection control valve 9, a pressure increase device 4, and a pressure increase control valve 11. Note that the fuel injection control using the fuel injection device of the present embodiment is executed by the controller 30.

  The fuel pressurizing pump 1 pumps up fuel stored in a tank (not shown) and supplies the fuel to the first pressure accumulating chamber 31. The first pressure accumulating chamber 31 stores the fuel supplied from the fuel pressurizing pump 1 at a predetermined pressure. The second pressure accumulation chamber 32 accumulates fuel supplied from the first pressure accumulation chamber 31 via the differential pressure generation valve 33 at a predetermined pressure. The pressure sensor 41 detects the fuel pressure in the first pressure accumulation chamber 31. The detection value of the pressure sensor 41 is input to the controller 30, and the drive control of the fuel pressurizing pump 1 is performed by the controller 30 so that the fuel pressure in the first pressure accumulation chamber 31 becomes the set pressure. The set pressure here is a value of about 40 to 120 MPa, for example, and a larger value is set in the controller 30 as the engine speed and the required torque (drive load) are higher.

  The pressure booster 4 has a pressure boosting piston 10 and a spring 15, and a first cylinder chamber 34, a second cylinder chamber 35, and a pressure booster control chamber 14 are formed in the pressure booster 4. Yes. The first cylinder chamber 34 communicates with the second pressure accumulation chamber 32, and fuel is supplied to the first cylinder chamber 34 from the second pressure accumulation chamber 32. The pressure increasing piston 10 is pressurized by the pressure of the fuel supplied into the first cylinder chamber 34. The second cylinder chamber 35 communicates with the first pressure accumulating chamber 31 via the pressure shut-off valve 17, and fuel is supplied from the first pressure accumulating chamber 31 to the second cylinder chamber 35 via the pressure shut-off valve 17. Supplied. The pressure booster control chamber 14 communicates with the second pressure accumulation chamber 32 and the tank via the pressure boost control valve 11, and the pressure of fuel from the second pressure accumulation chamber 32 in the pressure booster control chamber 14. Can be supplied, and the pressure in the pressure intensifier control chamber 14 can be released. Here, supply / release of pressure in the pressure booster control chamber 14 can be switched by the pressure boost control valve 11.

  As shown in FIG. 2, the area A1 that receives the fuel pressure in the first cylinder chamber 34 with respect to the plane perpendicular to the sliding direction of the booster piston 10 is the area that receives the fuel pressure in the second cylinder chamber 35. Greater than A3. Furthermore, if the area that receives the fuel pressure in the pressure booster control chamber 14 is A2, the relationship A1 = A2 + A3 is established. The spring 15 generates a force that biases the pressure-increasing piston 10 toward the first cylinder chamber 34.

  The pressure increase control valve 11 communicates the pressure increase device control chamber 14 and the second pressure accumulation chamber 32 to supply fuel pressure in the second pressure accumulation chamber 32 to the pressure increase device control chamber 14. It is possible to switch between the second state in which the pressure in the pressure booster control chamber 14 is released by communicating the pressure booster control chamber 14 and the tank. When the pressure-increasing control valve 11 is switched from the first state to the second state, the pressure in the pressure-increasing device control chamber 14 is released, so that the fuel pressure in the second cylinder chamber 35 increases. Thus, the fuel pressure in the pressure booster control chamber 14 functions as a control pressure that acts on the pressure boosting piston 10 in order to change the fuel pressure in the second cylinder chamber 35.

  A fuel sump 6 is formed in the nozzle 5, and the fuel sump 6 communicates with the first pressure accumulation chamber 31 through the oil passage 7 and the pressure shut-off valve 17, and also through the oil passages 7 and 8. And communicates with the second cylinder chamber 35. An injection hole 20 is formed in the sheet portion 16 of the nozzle 5, and a needle 13 that opens and closes communication between the fuel reservoir 6 and the injection hole 20 is slidably accommodated in the nozzle 5.

  The operation of the needle 13 is performed by releasing the fuel pressure in the injector control chamber 3. Here, the injector control chamber 3 communicates with the first pressure accumulation chamber 31 via the orifice 18 and the pressure shut-off valve 17, and communicates with the second cylinder chamber 35 via the orifice 18 and the oil passage 8. Yes. When fuel pressure is supplied to the injector control chamber 3, the needle 13 does not operate and the fuel stored in the fuel reservoir 6 is not injected.

  By operating the injection control valve 9, the fuel in the injector control chamber 3 is discharged through the orifice 19, and the command piston 12 and the needle 13 are moved to the injector control chamber 3 side, and the fuel reservoir 6 and the injection hole 20 are moved. And the fuel stored in the fuel reservoir 6 is injected from the injection hole 20 into a combustion chamber of an internal combustion engine (not shown). Here, when the injection control valve 9 is operated in a state where the pressure increase control valve 11 is maintained in the first state, the fuel accumulated in the first pressure accumulation chamber 31 is increased by the pressure increase device 4. It is injected without.

  On the other hand, when the pressure increase control valve 11 is switched from the first state to the second state and the injection control valve 9 is operated, the fuel pressure in the second cylinder chamber 35 increases and the fuel stored in the fuel reservoir 6 increases. Since the pressure increases, the fuel is boosted by the pressure booster 4 and injected. As described above, the fuel injection device according to the present embodiment can inject the fuel accumulated in the first pressure accumulation chamber 31 by further increasing the pressure by the pressure increasing device 4.

  The pressure shut-off valve 17 is provided to prevent the fuel boosted by the pressure booster 4 from flowing back to the first pressure accumulation chamber 31. Here, the pressure shut-off valve 17 can be constituted by a check valve that allows the flow of fuel only in the direction from the first accumulator 31 to the second cylinder chamber 35 and the fuel reservoir 6.

  The controller 30 controls the discharge flow rate of the fuel pressurizing pump 1 so that the fuel pressure in the first pressure accumulation chamber 31 becomes the set pressure. The controller 30 controls the fuel injection timing by controlling the operation timing of the injection control valve 9. Further, the controller 30 also performs switching control of the pressure increase control valve 11 in order to inject fuel by increasing the pressure by the pressure increasing device 4.

In the present embodiment, a first pressure accumulation chamber 31 and a second pressure accumulation chamber 32 are provided as pressure accumulation chambers (common rails) for accumulating fuel. Here, the first pressure accumulation chamber 31 functions as a fuel supply source to the fuel reservoir 6, the injector control chamber 3 and the second cylinder chamber 35, and the second pressure accumulation chamber 32 controls the first cylinder chamber 34 and the pressure booster. It functions as a fuel supply source to the chamber 14. The volume of the second pressure accumulation chamber 32 is set larger than the volume of the first pressure accumulation chamber 31. This is because it is necessary to quickly increase the pressure of the fuel in the first pressure accumulating chamber 31 at the time of starting the internal combustion engine, and when the fuel is boosted by the pressure booster 4 and injected, This is because it is necessary to supply the second pressure accumulation chamber 32 to the first cylinder chamber 34. As a typical example, the volume of the first pressure accumulation chamber 31 is 50 cm ³ or less, and the volume of the second pressure accumulation chamber 32 is 100 cm ³ or more.

  Further, a differential pressure generating valve 33 is provided between the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32, and the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 are subjected to a predetermined condition. Communication is blocked by the differential pressure generating valve 33. Hereinafter, an example of a more detailed configuration of the differential pressure generating valve 33 will be described with reference to FIG. As shown in FIG. 3, the differential pressure generating valve 33 has valves 301, 302, and 303.

  The valve 301 has a flow path 304 and a flow path 305 communicating with the first pressure accumulation chamber 31 when the fuel pressure in the first pressure accumulation chamber 31 is larger than a predetermined value X1 (for example, a value of about 30 to 35 MPa). To communicate. On the other hand, when the fuel pressure in the first pressure accumulation chamber 31 is equal to or less than the predetermined value X1, the valve 301 is closed. Thus, when the fuel pressure in the first pressure accumulation chamber 31 is equal to or less than the predetermined value X1, the supply of fuel from the first pressure accumulation chamber 31 to the second pressure accumulation chamber 32 is shut off.

  The valve 302 is provided in series with the valve 301 on the second pressure accumulation chamber 32 side. When the difference between the fuel pressure in the first pressure accumulation chamber 31 and the fuel pressure in the second pressure accumulation chamber 32 is larger than a predetermined value X2 (for example, a value of about 2 to 5 MPa), the valve 302 has a flow path. The flow path 306 communicated with 305 and the second pressure accumulation chamber 32 is communicated. On the other hand, when the difference between the fuel pressure in the first pressure accumulation chamber 31 and the fuel pressure in the second pressure accumulation chamber 32 is equal to or less than a predetermined value X2, the valve 302 is closed.

  The valve 303 is provided in parallel with the valve 302. The valve 303 causes the flow path 305 and the flow path 306 to communicate when the fuel pressure in the second pressure accumulation chamber 32 is greater than the fuel pressure in the first pressure accumulation chamber 31. On the other hand, when the fuel pressure in the first pressure accumulation chamber 31 is equal to or higher than the fuel pressure in the second pressure accumulation chamber 32, the valve 303 is closed.

  From the operations of the valves 302 and 303 described above, the difference between the fuel pressure in the first pressure accumulation chamber 31 and the fuel pressure in the second pressure accumulation chamber 32 is equal to or less than a predetermined value X2 and the first pressure accumulation chamber 31 When the fuel pressure at is higher than the fuel pressure in the second pressure accumulating chamber 32, the communication between the flow path 305 and the flow path 306 is blocked.

  Next, the operation of the fuel injection device according to this embodiment will be described. It is assumed that fuel is not accumulated in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 before the internal combustion engine is started.

  When starting the internal combustion engine, the fuel pressurizing pump 1 is driven to supply fuel to the first pressure accumulation chamber 31. Here, the valve 301 is closed, and fuel is not supplied to the second pressure accumulating chamber 32, so that the fuel pressure in the first pressure accumulating chamber 31 quickly rises. By operating the injection control valve 9, fuel is injected into the combustion chamber and the internal combustion engine is started.

  When the fuel pressure in the first pressure accumulation chamber 31 becomes greater than the predetermined value X1, the valves 301 and 302 are opened, and fuel is supplied from the first pressure accumulation chamber 31 to the second pressure accumulation chamber 32. Here, the valve 303 is closed. When the fuel is supplied to the second pressure accumulating chamber 32 and the difference between the fuel pressure in the first pressure accumulating chamber 31 and the fuel pressure in the second pressure accumulating chamber 32 becomes a predetermined value X2 or less, the valve 302 is closed. Thus, the supply of fuel from the first pressure accumulation chamber 31 to the second pressure accumulation chamber 32 is cut off, so that the fuel pressure in the first pressure accumulation chamber 31 is greater than the fuel pressure in the second pressure accumulation chamber 32. High state is maintained.

  During low load operation of the internal combustion engine, the fuel is injected without increasing the pressure by the pressure increasing device 4 by operating the injection control valve 9 with the pressure increasing control valve 11 kept in the first state. On the other hand, during high-load operation of the internal combustion engine, the pressure increase control valve 11 is switched from the first state to the second state, and the injection control valve 9 is operated to inject fuel by increasing the pressure by the pressure increase device 4. When the needle 13 is operated, the pressure-increasing piston 10 pressurized by the fuel in the first cylinder chamber 34 moves to the second cylinder chamber 35 side, and the fuel is pressurized and injected. When the difference between the pressure in the first pressure accumulation chamber 31 and the pressure in the second pressure accumulation chamber 32 becomes larger than the predetermined value X2 by the operation of the pressure booster 4, the valve 302 is opened and the first pressure accumulation chamber 31 is opened. Is supplied to the second pressure accumulating chamber 32. At this time, the relationship between the pressure in the first pressure accumulation chamber 31 and the pressure in the second pressure accumulation chamber 32 moves substantially on the solid line in FIG. The difference from the pressure in the second pressure accumulating chamber 32 is kept substantially at the predetermined value X2.

  When the pressure-increasing piston 10 is returned to the initial position after the fuel is boosted and injected by the pressure-intensifying device 4, the pressure-increasing control valve 11 is switched from the second state to the first state. Immediately after switching the pressure-increasing control valve 11 to the first state, fuel flows from the second pressure accumulating chamber 32 into the pressure-increasing device control chamber 14 and the pressure-increasing piston 10 is moved to the first cylinder chamber 34 by the restoring force of the spring 15. Move to the side. Thereafter, the pressure-increasing piston 10 moves toward the first cylinder chamber 34 by the restoring force of the spring 15. Further, when the pressure increasing piston 10 is returned, fuel is supplied from the first pressure accumulating chamber 31 to the second cylinder chamber 35, and the pressure of the fuel in the second cylinder chamber 35 also acts as a restoring force of the pressure increasing piston 10. To do. Here, since the pressure of the fuel in the first pressure accumulation chamber 31 is higher than the pressure of the fuel in the second pressure accumulation chamber 32 by the operation of the valve 302, the pressure of the fuel in the second cylinder chamber 35 is increased. 34 and the pressure of the fuel in the pressure booster control chamber 14 become higher. Therefore, since a restoring force larger than that in the past can be applied to the pressure increasing piston 10, the time required to return the pressure increasing piston 10 to the initial position can be shortened.

  In addition, when it is determined that the fuel in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 needs to be decompressed in a short time, the controller 30 performs the decompression control described below. In this pressure reduction control, the fuel pressurization pump 1 is stopped or the discharge flow rate is lowered, and the pressure increase control valve 11 is temporarily set to the first without operating the injection control valve 9, that is, without operating the needle 13. This is done by switching from the state to the second state. When the pressure increase control valve 11 is switched from the first state to the second state, the pressure in the pressure increase device control chamber 14 is released, and when the pressure increase control valve 11 is switched from the second state to the first state, the pressure increase device control chamber. 14 is supplied with the fuel pressure from the second pressure accumulating chamber 32. By this switching operation, the fuel in the second pressure accumulating chamber 32 is discharged and the pressure decreases. When the difference between the fuel pressure in the first pressure accumulation chamber 31 and the fuel pressure in the second pressure accumulation chamber 32 becomes larger than a predetermined value X2, the valve 302 is opened, so that the fuel in the first pressure accumulation chamber 31 Is discharged via the second pressure accumulating chamber 32 and the pressure booster control chamber 14, so that the fuel pressure in the first pressure accumulating chamber 31 is also reduced. When it is necessary to further reduce the pressure, the fuel is repeatedly discharged by repeating this switching operation to further reduce the pressure.

  As an example of performing the above-described pressure reduction control, when the rotational deceleration (time reduction amount of the rotational speed) of the internal combustion engine is greater than or equal to a predetermined value, For example, when the fuel cut is performed, when the internal combustion engine is stopped, the fuel pressure in the first pressure accumulation chamber 31 detected by the pressure sensor 41 is higher than the set pressure by a predetermined value.

  Further, it is conceivable that a very small amount of fuel is injected and pressure is reduced without increasing the pressure by the pressure increasing device 4. In this case, when the fuel pressure in the first pressure accumulation chamber 31 becomes lower than the fuel pressure in the second pressure accumulation chamber 32, the valve 303 is opened to move from the second pressure accumulation chamber 32 to the first pressure accumulation chamber 31. Since the fuel is supplied, the pressure reduction speed in the first pressure accumulation chamber 31 is slow. At this time, the relationship between the pressure in the first pressure accumulation chamber 31 and the pressure in the second pressure accumulation chamber 32 moves substantially on the broken line in FIG. 5, and the pressure in the second pressure accumulation chamber 32 is It becomes higher than the appropriate value set by the valve 302. This state can be estimated based on the driving history of the fuel pressurizing pump 1 and the pressure booster 4 and the detection value of the pressure sensor 41. Alternatively, the pressure in the second pressure accumulation chamber 32 may be directly detected by a pressure sensor. Even when this state is estimated or detected, the pressure in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 is decreased by performing the above-described pressure reduction control. As the pressure decreases, the relationship between the pressure in the first pressure accumulating chamber 31 and the pressure in the second pressure accumulating chamber 32 also moves substantially on the solid line in FIG. In this case, an operation of temporarily switching the pressure increase control valve 11 from the first state to the second state without operating the injection control valve 9 while avoiding the fuel injection period is performed.

  As described above, according to this embodiment, since the valve 301 is closed when the internal combustion engine is started, only the first pressure accumulation chamber 31 out of the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 is fueled. Fuel from the pressurizing pump 1 is supplied. Since the volume of the first pressure accumulating chamber 31 is smaller than the volume of the second pressure accumulating chamber 32, the pressure of the fuel in the first pressure accumulating chamber 31 can be quickly increased when the internal combustion engine is started. Therefore, the startability of the internal combustion engine can be improved.

  Then, the valves 302 and 303 are opened and closed so that the fuel pressure in the first pressure accumulation chamber 31 is higher than the fuel pressure in the second pressure accumulation chamber 32. Thus, when the pressure-increasing piston 10 is returned to the initial position after the fuel is boosted and injected by the pressure-intensifying device 4, the pressure of the fuel in the second cylinder chamber 35 is controlled by the first cylinder chamber 34 and the pressure-increasing device. Since it can be made higher than the pressure of the fuel in the chamber 14, the restoring force for returning the pressure increasing piston 10 to the initial position can be increased. Therefore, since the time required to return the pressure boosting piston 10 to the initial position can be shortened, the pressure boosting device 4 can be stably operated during high speed operation of the internal combustion engine. Furthermore, since the degree of freedom in designing the spring 15 for applying a restoring force to the pressure increasing piston 10 is increased, the pressure increasing device 4 can be downsized.

  Further, when it is necessary to reduce the pressure in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 in a short time, the pressure is increased without operating the injection control valve 9, that is, without operating the needle 13. The pressure control valve 11 is temporarily switched from the first state to the second state. As a result, the fuel accumulated in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 can be discharged via the pressure intensifier control chamber 14, so that the first pressure accumulation chamber 31 and the second pressure accumulation chamber 31 The pressure of the fuel in the pressure accumulating chamber 32 can be quickly reduced without using a pressure reducing valve.

“Second Embodiment”
FIG. 6 is a diagram showing an outline of a configuration of a fuel injection device to be controlled by the control device according to the second embodiment of the present invention. In the present embodiment, compared with the first embodiment, the pressure accumulation chamber (common rail) for accumulating fuel is not divided and is shared, and the differential pressure generating valve 33 is omitted. That is, the pressure accumulation chamber 31 of the present embodiment functions as a fuel supply source to the fuel reservoir 6, the injector control chamber 3, the first cylinder chamber 34, the second cylinder chamber 35, and the pressure booster control chamber 14. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  Also in this embodiment, when the pressure-increasing piston 10 is returned to the initial position after the fuel is boosted and injected by the pressure-intensifying device 4, the pressure-increasing control valve 11 is switched from the second state to the first state.

  Here, immediately after the fuel is boosted and injected by the pressure booster 4, high-pressure fuel still remains in the second cylinder chamber 35. Immediately after switching the pressure increasing control valve 11 from the second state to the first state, the pressure of the fuel flowing into the pressure increasing device control chamber 14 is increased in addition to the pressure of the fuel in the second cylinder chamber 35. Since it acts on the piston 10, the restoring force to return the pressure-increasing piston 10 to the initial position is large, and the return speed of the pressure-increasing piston 10 is fast as shown in the initial return amount portion of FIG. However, after that, the boosting piston 10 returns only by the restoring force of the spring 15, so that the return speed of the boosting piston 10 becomes slow as shown in the return gradient α portion of FIG. 7. Therefore, as shown in FIG. 8, it takes time for the pressure-increasing piston 10 to completely return to the initial position, and during the high speed operation of the internal combustion engine, the second cylinder chamber 35 side again before the pressure-increasing piston 10 returns to the initial position. Will be moved to. If this operation is repeated, as shown in FIG. 8, the stroke amount of the pressure increasing piston 10 becomes insufficient, and the pressure increasing device 4 cannot sufficiently increase the pressure of the fuel.

  Therefore, in the present embodiment, when the pressure increase control valve 11 is switched from the second state to the first state and the pressure increase piston 10 is returned, the controller 30 does not operate the injection control valve 9, that is, the needle 13. The pressure increase control valve 11 is temporarily switched from the first state to the second state without operating the. When the pressure increase control valve 11 is switched to the second state, the pressure in the pressure increase device control chamber 14 is released and the fuel pressure in the second cylinder chamber 35 increases. When the pressure increase control valve 11 is switched to the first state in this state, not only the restoring force of the spring 15 but also the increased fuel pressure in the second cylinder chamber 35 and the fuel flowing into the pressure increaser control chamber 14 are obtained. The pressure also acts as a restoring force of the pressure increasing piston 10. Therefore, as shown in FIG. 9, the return speed of the pressure increasing piston 10 can be temporarily increased, so that the time required to return the pressure increasing piston 10 to the initial position can be shortened. The timing for temporarily switching the pressure-increasing control valve 11 to the second state is preferably after the return speed of the pressure-increasing piston 10 has slowed, and this timing can be set experimentally or analytically.

  This switching control is not limited to once in one cycle, and may be repeated a plurality of times in one cycle. Further, this switching control may be performed by predicting the occurrence of a stroke shortage of the boosting piston 10 without performing it every time the boosting piston 10 is returned. As an example of the case where occurrence of a stroke shortage of the boosting piston 10 is predicted, this switching control is performed during a predetermined cycle when the rotational speed of the internal combustion engine is equal to or higher than a predetermined value, or when the required torque of the internal combustion engine is higher than a predetermined value. For example, the fuel is boosted by the pressure booster 4 and injected without performing the above.

  Also in this embodiment, when the controller 30 determines that the fuel in the first pressure accumulation chamber 31 and the second pressure accumulation chamber 32 needs to be depressurized in a short time, the controller 30 performs the pressure reduction control described below. Do. As in the first embodiment, this pressure reduction control stops the fuel pressurization pump 1 or reduces the discharge flow rate, and controls the pressure increase without operating the injection control valve 9, that is, without operating the needle 13. This is done by temporarily switching the valve 11 from the first state to the second state. When the pressure increase control valve 11 is switched from the first state to the second state, the pressure in the pressure increase device control chamber 14 is released, and when the pressure increase control valve 11 is switched from the second state to the first state, the pressure increase device control chamber. 14 is supplied with the fuel pressure from the pressure accumulating chamber 31. By this switching operation, the fuel in the pressure accumulating chamber 31 is discharged and the pressure decreases. When it is necessary to further reduce the pressure, the fuel is repeatedly discharged by repeating this switching operation to further reduce the pressure.

  As an example of performing the above-described pressure reduction control, when the rotational deceleration (time reduction amount of the rotational speed) of the internal combustion engine is greater than or equal to a predetermined value, when the decrease rate of the required torque of the internal combustion engine is greater than or equal to a predetermined value, For example, when the fuel cut is performed, when the internal combustion engine is stopped, the fuel pressure in the pressure accumulation chamber 31 detected by the pressure sensor 41 is higher than the set pressure by a predetermined value.

  In addition, it is conceivable that a very small amount of fuel is injected and the pressure is reduced without increasing the pressure by the pressure increasing device 4. In this case, too, the pressure in the pressure accumulating chamber 31 is reduced by performing the pressure reduction control described above. Let However, in that case, an operation of temporarily switching the pressure increase control valve 11 from the first state to the second state without operating the injection control valve 9 while avoiding the fuel injection period is performed.

  Since other operations are the same as those in the first embodiment, description thereof is omitted.

  As described above, according to the present embodiment, after the fuel is boosted and injected by the booster 4, the booster control valve 11 is switched from the second state to the first state and the booster piston 10 is returned. The pressure increase control valve 11 is temporarily switched from the first state to the second state without operating the injection control valve 9, that is, without operating the needle 13. As a result, the increased pressure of the fuel in the second cylinder chamber 35 and the pressure of the fuel flowing into the pressure-increasing device control chamber 14 can act as a restoring force of the pressure-increasing piston 10. The return speed can be temporarily increased. Therefore, since the time required to return the pressure boosting piston 10 to the initial position can be shortened, the pressure boosting device 4 can be stably operated during high speed operation of the internal combustion engine. Furthermore, since the degree of freedom in designing the spring 15 for applying a restoring force to the pressure increasing piston 10 is increased, the pressure increasing device 4 can be downsized.

  When it is necessary to reduce the pressure in the pressure accumulating chamber 31 in a short time, the pressure increase control valve 11 is temporarily set to the first without operating the injection control valve 9, that is, without operating the needle 13. The state is switched to the second state. As a result, the fuel accumulated in the pressure accumulating chamber 31 can be discharged via the pressure intensifier control chamber 14, so that the fuel pressure in the pressure accumulating chamber 31 can be quickly reduced without using a pressure reducing valve. Can do.

  In FIG. 1, the first accumulator chamber 31 and the second accumulator chamber 32 are shown separately in appearance, but actually, it is not necessary to divide into two in appearance, and the inside of one common rail is divided. The structure which attached the differential pressure generating valve may be sufficient.

  In FIG. 1, regarding the oil passage from the second pressure accumulation chamber 32 to the injector 100, the oil passage to the first cylinder chamber 34 and the oil passage to the pressure increase control valve 11 are separate, but the oil passage is outside the injector 100. The oil path may be configured so that the path is shared and branched in the injector 100. Similarly, in FIG. 6, regarding the oil passage from the pressure accumulation chamber 31 to the injector 100, the oil passage to the pressure cutoff valve 17, the oil passage to the first cylinder chamber 34, and the oil passage to the pressure increase control valve 11 are separated. However, the oil passage may be configured so that the oil passage is shared outside the injector 100 and branched in the injector 100.

  1 and 6, the pressure increase control valve 11 is shown as a three-way valve, but a two-way valve type may be used. In FIGS. 1 and 6, a spring 15 that applies a restoring force to the pressure boosting piston 10 is provided in the pressure booster control chamber 14, but the spring 15 is provided in the first cylinder chamber 34 and the second cylinder chamber 35. May be provided.

  For example, when the arrangement of the pressure accumulating chamber is limited as in a V-type engine, a plurality of first accumulating chambers 31 and a plurality of second accumulating chambers 32 are provided in the first embodiment, and the accumulating chamber 31 is provided in the second embodiment. It is also possible to provide a plurality.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure which shows the outline of a structure of the fuel-injection apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the outline of a structure of a pressure booster. It is a figure which shows the outline of a structure of a differential pressure generating valve. It is a figure explaining the relationship between a 1st pressure accumulation chamber and a 2nd pressure accumulation chamber. It is a figure explaining the relationship between a 1st pressure accumulation chamber and a 2nd pressure accumulation chamber. It is a figure which shows the outline of a structure of the fuel-injection apparatus used as the control object of the control apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the return operation | movement of a pressure increase piston. It is a figure explaining the phenomenon in which pressure increase is performed again without a pressure increase piston returning to an initial position. It is a figure which shows the example which accelerated the return speed of the pressure increase piston.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel pressurization pump, 3 Injector control chamber, 4 Pressure booster, 5 Nozzle, 6 Fuel reservoir, 9 Injection control valve, 10 Pressure boosting piston, 11 Pressure boost control valve, 13 Needle, 14 Pressure booster control chamber, 15 Spring, 17 Pressure shut-off valve, 20 Injection hole, 30 Controller, 31 First pressure accumulation chamber, 32 Second pressure accumulation chamber, 33 Differential pressure generating valve, 34 First cylinder chamber, 35 Second cylinder chamber, 100 Injector, 301 , 302, 303 Valves.

Claims (15)

Pressure accumulation means for accumulating fuel supplied from the pump;
A pressure-increasing piston that is pressurized by the pressure of fuel supplied from the pressure accumulating means to the first cylinder chamber, and the pressure-increasing piston applies a force that pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber. Pressure increasing means for increasing the pressure of the fuel stored in the fuel reservoir communicating with the second cylinder chamber by increasing it by a change in the control force acting on the pressure increasing piston;
An injection nozzle for injecting fuel stored in the fuel reservoir by the operation of a needle;
A fuel injection device capable of increasing and injecting fuel accumulated in the pressure accumulating means by the pressure increasing means,
The pressure accumulating means is
A first pressure accumulation chamber that communicates with the second cylinder chamber and accumulates fuel supplied from a pump;
A second pressure accumulation chamber having a larger volume than the first pressure accumulation chamber, communicating with the first cylinder chamber, and accumulating fuel supplied from the first pressure accumulation chamber;
A shutoff valve that shuts off the supply of fuel from the first pressure accumulation chamber to the second pressure accumulation chamber when the pressure of the fuel in the first pressure accumulation chamber is equal to or less than a predetermined value;
A fuel injection device comprising: Pressure accumulation means for accumulating fuel supplied from the pump;
A pressure-increasing piston that is pressurized by the pressure of fuel supplied from the pressure accumulating means to the first cylinder chamber, and the pressure-increasing piston applies a force that pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber. Pressure increasing means for increasing the pressure of the fuel stored in the fuel reservoir communicating with the second cylinder chamber by increasing it by a change in the control force acting on the pressure increasing piston;
An injection nozzle for injecting fuel stored in the fuel reservoir by the operation of a needle;
A fuel injection device capable of increasing and injecting fuel accumulated in the pressure accumulating means by the pressure increasing means,
The pressure accumulating means is
A first pressure accumulation chamber that communicates with the second cylinder chamber and accumulates fuel supplied from a pump;
A second pressure accumulation chamber that communicates with the first cylinder chamber and accumulates fuel supplied from the first pressure accumulation chamber;
A differential pressure generating valve that opens and closes between the first pressure accumulation chamber and the second pressure accumulation chamber so that the pressure of the fuel in the first pressure accumulation chamber is higher than the pressure of the fuel in the second pressure accumulation chamber;
A fuel injection device comprising: The fuel injection device according to claim 2,
The differential pressure generating valve supplies fuel from the first pressure accumulation chamber to the second pressure accumulation chamber when the difference between the fuel pressure in the first pressure accumulation chamber and the fuel pressure in the second pressure accumulation chamber is a predetermined value or less. A fuel injection device including a shut-off valve. The fuel injection device according to claim 2 or 3,
The differential pressure generating valve includes a valve for communicating the first pressure accumulation chamber and the second pressure accumulation chamber when the pressure of the fuel in the second pressure accumulation chamber is larger than the pressure of the fuel in the first pressure accumulation chamber. Fuel injection device. Pressure accumulation means for accumulating fuel supplied from the pump;
A pressure increasing piston that is pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber, and controls the force by which the pressure increasing piston pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber A pressure increasing means for increasing the pressure of the fuel stored in the fuel reservoir communicating with the second cylinder chamber by increasing the pressure by releasing the pressure in the chamber;
Switching means capable of switching between a first state in which the control pressure is supplied into the control chamber and a second state in which the pressure in the control chamber is released;
An injection nozzle for injecting fuel stored in the fuel reservoir by the operation of a needle;
For the fuel injection device comprising the above, the switching means is switched from the first state to the second state and the needle is operated to increase the pressure accumulated in the pressure accumulating means by the pressure increasing means. A control device capable of being injected and
After the fuel is boosted by the pressure boosting means and injected, when the switching means is switched from the second state to the first state and the position of the boosting piston moved is returned, the fuel in the second cylinder chamber is returned. A control device for a fuel injection device, comprising: control means for performing switching control for temporarily switching the switching means from the first state to the second state without operating the needle so that the pressure increases. It is a control apparatus of the fuel-injection apparatus of Claim 5, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when a rotational speed of an internal combustion engine into which fuel is injected is a predetermined value or more. It is a control apparatus of the fuel-injection apparatus of Claim 5, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when a required torque of an internal combustion engine into which fuel is injected is a predetermined value or more. It is a control apparatus of the fuel-injection apparatus of Claim 5, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when the fuel is boosted and injected by the pressure increasing means without performing the switching control for a predetermined cycle. Pressure accumulation means for accumulating fuel supplied from the pump;
A pressure increasing piston that is pressurized by the pressure of the fuel supplied from the pressure accumulating means to the first cylinder chamber, and controls the force by which the pressure increasing piston pressurizes the fuel supplied from the pressure accumulating means to the second cylinder chamber A pressure increasing means for increasing the pressure of the fuel stored in the fuel reservoir communicating with the second cylinder chamber by increasing the pressure by releasing the pressure in the chamber;
Switching means capable of switching between a first state in which the control chamber and the pressure accumulating means communicate with each other and a second state in which the pressure in the control chamber is released;
An injection nozzle for injecting fuel stored in the fuel reservoir by the operation of a needle;
For the fuel injection device comprising the above, the switching means is switched from the first state to the second state and the needle is operated to increase the pressure accumulated in the pressure accumulating means by the pressure increasing means. A control device capable of being injected and
Control means for reducing the pressure of the fuel in the pressure accumulating means without injecting fuel by performing switching control for temporarily switching the switching means from the first state to the second state without operating the needle. A control device for a fuel injection device. A control device for a fuel injection device according to claim 9,
A control device for a fuel injection device, wherein the control means repeatedly performs the switching control. A control device for a fuel injection device according to claim 9 or 10,
The control device of the fuel injection device, wherein the control means performs the switching control while avoiding a fuel injection period in an operation state in which fuel injection is performed. It is a control apparatus of the fuel-injection apparatus of any one of Claims 9-11, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when a rotational deceleration of an internal combustion engine into which fuel is injected is a predetermined value or more. It is a control apparatus of the fuel-injection apparatus of any one of Claims 9-11, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when a reduction rate of a required torque of an internal combustion engine into which fuel is injected is a predetermined value or more. It is a control apparatus of the fuel-injection apparatus of any one of Claims 9-11, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when the pressure of the fuel in the pressure accumulating means is higher than a set pressure by a predetermined value or more. It is a control apparatus of the fuel-injection apparatus of any one of Claims 9-11, Comprising:
The control device of the fuel injection device, wherein the control means performs the switching control when the fuel injection to the internal combustion engine is stopped.

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