WO2018037714A1 - Fuel injection device - Google Patents

Abstract

A fuel injection device including: a valve body (31) having formed therein an injection hole (30), a supply flow path (40), a pressure control chamber (43), and an outflow flow path (42); a valve member (32) that opens and closes the injection hole; a switching valve mechanism (36) that has a first valve body (35, 352), a second valve body (37), and a third valve body (38, 382) and switches the flow path area of the outflow flow path; and a drive unit (33) that switch controls the lift amount of the first valve body to a first lift amount or a second lift amount. A switching chamber communicates with the pressure control chamber. Insertion holes (37e, 38e) being part of the outflow flow path are formed in the second valve body and the third valve body, respectively. The switching valve mechanism restricts the outflow flow path to a first throttle state if the first valve body is at a first lift amount position and restricts the outflow flow path to a second throttle state having a flow path area different from the first throttle state if the first valve body is at the second lift amount position.

Description

Fuel injection device Cross-reference of related applications

This application is based on Japanese Patent Application No. 2016-164005 filed on August 24, 2016, the contents of which are incorporated herein by reference.

The present disclosure relates to a fuel injection device that injects fuel from an injection hole.

Conventionally, as disclosed in Patent Document 1, for example, the needle opening speed for injecting fuel is made variable. As a specific mechanism for making the needle valve opening speed variable, two solenoids are installed, and the solenoids are operated independently to control the discharge speed of the fuel flowing out from the control chamber in two stages.

US Patent Application Publication No. 2013/0233941

In the above-described prior art, since the discharge speed is varied by mounting two solenoids, there is a possibility that the fuel injection device may be increased in size as compared with the configuration having one solenoid.

Therefore, an object of the present disclosure is to provide a fuel injection device capable of variably controlling the fuel discharge speed while suppressing an increase in size.

The fuel injection device according to one aspect of the present disclosure injects fuel from the injection hole. The fuel injection device includes an injection hole, a supply flow path for supplying fuel to the injection hole, a pressure control chamber into which a part of the fuel flowing through the supply flow path flows, and an outflow flow for discharging the fuel in the pressure control chamber to the low pressure side The valve body in which the passage is formed, the valve member that opens and closes the nozzle hole by relative displacement with respect to the valve body due to the fluctuation of the fuel pressure in the pressure control chamber, and the switching chamber in the outflow passage. A switching valve mechanism that has one valve body, a second valve body that is disposed in the pressure control chamber, and a third valve body that is at least partially disposed in the pressure control chamber, and switches the flow passage area of the outflow passage And the first valve body is lifted by applying a driving force to the first valve body to switch the flow path area by the switching valve mechanism, and the lift amount of the first valve body is set to the first lift amount or A drive unit that performs switching control to a second lift amount larger than the first lift amount, The chamber communicates with the pressure control chamber, the second valve body and the third valve body are each formed with an insertion hole that is a part of the outflow channel, and the switching valve mechanism is the first valve body. When the first valve element is not lifted, the first valve element is seated on the valve body to close the outflow passage. When the first valve element is at the first lift amount, the first valve element is Since the second valve element and the third valve element are not separated from the body, the fuel passes through the insertion hole of the third valve element and restricts the outflow channel to the first throttle state. When the first valve body is in the second lift position, the first valve body is separated from the valve body, and the third valve body is moved by the first valve body against the third valve body. By being separated from the two valve bodies, the fuel passes through the insertion hole of the second valve body, and the outflow channel is limited to the second throttle state that is different from the first throttle state.

According to such this indication, when the 1st valve body is in the position of the 1st lift amount, the 1st valve body separated from the valve body does not separate the 2nd valve body and the 3rd valve body. In position. As a result, the fuel passes through the insertion hole of the third valve body, and the outflow channel can be brought into the first throttle state. Further, when the first valve body is in the second lift amount position, the first valve body that is separated from the valve body is in a position for separating the third valve body from the second valve body. As a result, the fuel passes through the insertion hole of the second valve body, and the outflow channel can be brought into the second throttle state.

Thus, the switching valve mechanism can switch the channel area of the outflow channel by adjusting the lift amount of the first valve body. And the lift amount of a 1st valve body can be controlled by one drive part. Therefore, since the drive part should just be the structure which controls the lift amount of one 1st valve body, a drive part can suppress an enlargement.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a diagram showing an overall configuration of a fuel supply system, FIG. 2 is a longitudinal sectional view showing the fuel injection device, FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of the switching valve mechanism, FIG. 4 is a diagram illustrating the operation of the switching valve mechanism, FIG. 5 is an enlarged longitudinal sectional view showing the vicinity of the switching valve mechanism of the second embodiment. FIG. 6 is a diagram showing the operation of the switching valve mechanism, FIG. 7 is an enlarged longitudinal sectional view showing the vicinity of the switching valve mechanism of the third embodiment, FIG. 8 is a diagram illustrating the operation of the switching valve mechanism.

Hereinafter, modes for carrying out the present disclosure will be described using a plurality of modes with reference to the drawings. In some embodiments, portions corresponding to the matters described in the preceding embodiments may be given the same reference numerals, or one letter may be added to the preceding reference numerals, and overlapping descriptions may be omitted. In addition, when a part of the configuration is described in each embodiment, the other parts of the configuration are the same as those of the embodiment described in advance. In addition to the combination of parts specifically described in each embodiment, the embodiments may be partially combined as long as the combination does not hinder the combination.

(First embodiment)
A first embodiment of the present disclosure will be described with reference to FIGS. The fuel supply system 10 shown in FIG. 1 uses the fuel injection device 100 according to the first embodiment. The fuel supply system 10 supplies fuel to each combustion chamber 22 of a diesel engine 20 that is an internal combustion engine by a fuel injection device 100. The fuel supply system 10 includes a feed pump (F / P) 12, a supply pump 13, a common rail 14, an engine control device 17, a plurality of fuel injection devices 100, and the like.

The feed pump 12 is, for example, a trochoid pump built in the supply pump 13. The feed pump 12 pumps light oil as fuel stored in the fuel tank to the supply pump 13. The feed pump 12 may be a separate body from the supply pump 13.

The supply pump 13 is, for example, a plunger type pump that is driven by the output shaft of the diesel engine 20. The supply pump 13 is connected to the common rail 14 by a fuel pipe 13a. The supply pump 13 further boosts the fuel supplied from the feed pump 12 and supplies the fuel to the common rail 14.

The common rail 14 is connected to each fuel injection device 100 via a high-pressure fuel pipe 14a. The common rail 14 temporarily stores high-pressure fuel supplied from the supply pump 13 and distributes the fuel to each fuel injection device 100 while maintaining the pressure. The common rail 14 is provided with a pressure reducing valve 14b. The pressure reducing valve 14b discharges the surplus fuel in the common rail 14 to the surplus fuel pipe connected to the fuel tank.

The engine control device 17 includes an arithmetic circuit mainly composed of a microcomputer or a microcontroller including a processor, a RAM, and a rewritable nonvolatile storage medium, and a drive circuit that drives each fuel injection device 100. It is. The engine control device 17 is electrically connected to each fuel injection device 100 as indicated by a broken line in FIG. The engine control device 17 controls the operation of each fuel injection device 100 according to the operating state of the diesel engine 20.

The fuel injection device 100 is attached to the head member 21 in a state of being inserted into the insertion hole of the head member 21 that forms the combustion chamber 22. The fuel injection device 100 directly injects fuel supplied through the high-pressure fuel pipe 14 a from the plurality of injection holes 30 toward the combustion chamber 22. The fuel injection device 100 includes a valve mechanism that controls fuel injection from the injection hole 30. The fuel injection device 100 uses part of the fuel supplied through the high-pressure fuel pipe 14 a to open and close the injection hole 30.

Next, the fuel injection device 100 will be described with reference to FIGS. As shown in FIG. 2, the fuel injection device 100 includes a valve body 31, a nozzle needle 32, a drive unit 33, and a switching valve mechanism 36. The switching valve mechanism 36 includes a first valve 35, a second valve 37, and a third valve 38.

The valve body 31 is configured by combining a plurality of members such as a cylinder formed of a metal material. The valve body 31 is formed with an injection hole 30, a seat part 39, a high-pressure channel 40, an inflow channel 41, a low-pressure channel 42, a pressure control chamber 43, a first valve chamber 45, and a drive unit accommodation chamber 46. .

The injection hole 30 is formed at the distal end in the insertion direction in the valve body 31 inserted into the combustion chamber 22. The tip is formed in a conical or hemispherical shape. A plurality of nozzle holes 30 are provided radially from the inside to the outside of the valve body 31. High-pressure fuel is injected from each injection hole 30 toward the combustion chamber 22. The high-pressure fuel is atomized by passing through the nozzle holes 30 and is easily mixed with air. The seat part 39 is formed in a conical shape inside the tip part of the valve body 31. The seat portion 39 faces the high-pressure channel 40 on the upstream side of the nozzle hole 30.

The high-pressure channel 40 supplies high-pressure fuel supplied from the common rail 14 to the nozzle hole 30 through the high-pressure fuel pipe 14a shown in FIG. The inflow channel 41 allows the high-pressure channel 40 and the pressure control chamber 43 to communicate with each other. The inflow channel 41 causes a part of the fuel flowing through the high-pressure channel 40 to flow into the pressure control chamber 43. The inflow channel 41 is provided with an in-orifice 48 as an inflow orifice. The in-orifice 48 restricts the flow rate of fuel flowing from the high-pressure channel 40 to the pressure control chamber 43.

The low pressure channel 42 extends in the valve body 31 along the high pressure channel 40. The low-pressure channel 42 is a part of the outflow channel that allows the fuel (leak fuel) in the pressure control chamber 43 to flow out to the surplus fuel pipe on the low-pressure side outside the fuel injection device 100. The outflow channel is constituted by a low-pressure channel 42, a first valve chamber, and the like. The pressure of the fuel flowing through the low pressure channel 42 is lower than the pressure of the fuel in the pressure control chamber 43.

The pressure control chamber 43 is provided inside the valve body 31 on the opposite side of the nozzle hole 30 with the nozzle needle 32 interposed therebetween. The pressure control chamber 43 is a cylindrical space defined by the cylinder 49 and the nozzle needle 32. High pressure fuel flows into the pressure control chamber 43 through the inflow passage 41. The fuel pressure in the pressure control chamber 43 varies depending on the inflow of high-pressure fuel from the inflow passage 41 and the outflow of fuel to the first valve chamber 45. The nozzle needle 32 is reciprocated by the fluctuation of the fuel pressure in the pressure control chamber 43.

The first valve chamber 45 is a cylindrical space that houses the first valve 35. The first valve chamber 45 communicates with the pressure control chamber 43. The first valve chamber 45 is located between the pressure control chamber 43 and the drive unit accommodation chamber 46. The axial direction of the first valve chamber 45 is along the axial direction of the pressure control chamber 43. The first valve chamber 45 and the pressure control chamber 43 are formed so as to be coaxial with each other. The volume of the first valve chamber 45 is smaller than the volume of the pressure control chamber 43. A downstream communication path 53 is formed between the first valve chamber 45 and the drive unit accommodation chamber 46. The downstream side communication passage 53 mainly causes the fuel discharged from the first valve chamber 45 to flow through the low pressure passage 42.

A first seat portion 54 is formed on the partition wall that partitions the first valve chamber 45. The first seat portion 54 is an annular region surrounding the periphery of the opening of the downstream communication passage 53 in the partition wall of the first valve chamber 45. The first seat portion 54 is a region where the first valve 35 is seated.

The drive unit accommodation chamber 46 is a columnar space that houses the drive unit 33. The drive unit accommodation chamber 46 is filled with a part of the fuel discharged from the first valve chamber 45. The axial direction of the drive unit accommodating chamber 46 is along the axial direction of the pressure control chamber 43 and the first valve chamber 45. The drive unit accommodation chamber 46, the first valve chamber 45, and the pressure control chamber 43 are provided so as to be coaxial with each other.

The nozzle needle 32 is formed in a cylindrical shape as a whole by a metal material. The nozzle needle 32 is accommodated in the valve body 31. The nozzle needle 32 is urged toward the nozzle hole 30 by a coiled nozzle spring 60 in which a metal wire is spirally wound. The nozzle needle 32 has a valve pressure receiving surface 61 and a face portion 62. The nozzle needle 32 is reciprocally displaced in the axial direction along the inner peripheral wall surface of the cylinder 49 formed in a cylindrical shape by receiving the fuel pressure in the pressure control chamber 43 on the valve pressure receiving surface 61. The nozzle needle 32 is displaced relative to the valve body 31, thereby causing the face portion 62 to be separated from and seated on the seat portion 39. The face portion 62 forms a main valve portion that opens and closes the nozzle hole 30 together with the seat portion 39.

The drive unit 33 is accommodated in the drive unit accommodation chamber 46. The drive unit 33 generates a driving force for driving the first valve 35 and the third valve 38 of the switching valve mechanism 36, so that the pressure control chamber 43 and the low-pressure flow path 42 are communicated from the cut-off state to the communication state. Switch to. The driving unit 33 can change the magnitude of the driving force to be generated based on the driving signal output from the engine control device 17, and can generate the first driving force or the second driving force. The second driving force is a force larger than the first driving force.

The driving unit 33 includes a piezoelectric element laminate 63, a transmission mechanism 64, and the like. The piezoelectric element laminate 63 is a laminate in which, for example, layers called PZT (PbZrTiO3) and thin electrode layers are alternately stacked. The piezoelectric element laminate 63 receives an input drive signal output from the engine control device 17. The piezoelectric element stacked body 63 expands and contracts along the axial direction of the drive unit accommodation chamber 46 by the inverse piezoelectric effect that is a characteristic of the piezoelectric element, according to the drive voltage that is a voltage corresponding to the drive signal.

The transmission mechanism 64 is a mechanism that transmits expansion and contraction of the piezoelectric element laminate 63. The transmission mechanism 64 includes a piston 65, a buffer cylinder 66, a piston spring 67, a first transmission piston 68, a second transmission piston 69, a first drive transmission pin 70, and a second drive transmission pin 71. The piston 65 is formed in a cylindrical shape. The piston 65 is in contact with the piezoelectric element laminate 63. The movement of the piezoelectric element laminate 63 that expands and contracts is input to the piston 65.

The buffer cylinder 66 is formed in a cylindrical shape and is fitted on the piston 65. The piston spring 67 is a metal spring that generates an elastic force in the axial direction. The piston spring 67 urges the piston 65 toward the first valve 35 with respect to the buffer cylinder 66.

A cylindrical first drive transmission pin 70 extending toward the first valve chamber 45 is disposed at the tip of the piston 65. The first drive transmission pin 70 is inserted through the downstream communication path 53. A columnar first transmission piston 68 extending toward the first valve chamber 45 is disposed at the tip of the first drive transmission pin 70. The first transmission piston 68 is inserted through the downstream communication path 53. The first drive transmission pin 70 and the first transmission piston 68 are arranged coaxially.

The downstream communication passage 53 defines a buffer oil tight chamber 72 between the first transmission piston 68 and the second transmission piston 69. The displacement of the first transmission piston 68 is transmitted to the second transmission piston 69 by the fuel filled in the buffer oil tight chamber 72. The second transmission piston 69 has a columnar shape and is inserted through the downstream communication path 53. A columnar second drive transmission pin 71 extending toward the first valve chamber 45 is disposed at the tip of the second transmission piston 69. The second drive transmission pin 71 is inserted through the downstream communication path 53. The distal end surface of the second drive transmission pin 71 is in contact with the first valve 35.

Thus, the drive unit 33 reciprocates the second drive transmission pin 71 in the axial direction by transmitting the expansion and contraction of the piezoelectric element laminate 63 along the axial direction by the transmission mechanism 64. As the drive voltage input to the drive unit 33 increases, the drive force input from the second drive transmission pin 71 to the first valve 35, and hence the lift amount of the first drive transmission pin 70 and the first valve 35, increases.

The switching valve mechanism 36 is a mechanism that switches the flow passage area of the outflow passage by opening and closing the first valve 35 and the third valve 38. When the drive unit 33 generates neither the first drive force nor the second drive force, the switching valve mechanism 36 closes the outflow channel. On the other hand, when the drive unit 33 generates the first driving force, the switching valve mechanism 36 restricts the outflow channel to the first throttle state. Further, when the drive unit 33 generates the second driving force, the switching valve mechanism 36 restricts the outflow channel to the second throttle state.

The second valve 37 is formed in a disk shape from a metal material or the like. The second valve 37 is disposed in the pressure control chamber 43 and can be displaced in the pressure control chamber 43 along the axial direction. The third valve 38 is also disposed in the pressure control chamber 43. The second valve 37 and the third valve 38 are arranged in series in the pressure control chamber 43. A through hole 37 a that penetrates the second valve 37 in the axial direction is formed in the center of the second valve 37 in the radial direction. The cylindrical portion 38a of the third valve 38 is inserted through the through hole 37a of the second valve 37, and guides the cylindrical portion 38a of the third valve 38 in the axial direction along the inner wall of the through hole 37a.

The second valve 37 is provided with an upper end side contact portion 37b, a lower end side contact portion 37c, and a second out orifice 37d. The upper end side contact portion 37 b is formed on the upper end surface of the second valve 37 facing the first valve chamber 45. The upper end side contact portion 37b is formed in a flat annular shape. The upper end side contact portion 37 b comes into contact with the second seat portion 50 by the elastic force of the third valve spring 55. The second valve 37 is closed by the seating of the upper end side contact portion 37b on the second seat portion 50. The second valve 37 is seated, thereby closing the in-orifice 48 of the inflow channel 41 and blocking the communication with the pressure control chamber 43. Further, the second valve 37 is separated to open the in-orifice 48 of the inflow channel 41 and to communicate with the pressure control chamber 43.

The lower end side contact portion 37 c is formed on the end surface facing the third valve 38 among the axial end surfaces of the second valve 37. In the lower end side contact portion 37 c, the disk portion 38 b of the third valve 38 comes into contact with the elastic force of the third valve spring 55.

The second out orifice 37d constitutes a part of the insertion hole 37e of the second valve 37. The insertion hole 37e of the second valve 37 passes through the upper end side contact portion 37b and the lower end side contact portion 37c. The second out orifice 37d is configured to restrict the flow area from the pressure control chamber 43 to the first valve chamber 45. The second out orifice 37d restricts the flow rate of the fuel flowing out from the pressure control chamber 43 to the first valve chamber 45 when the second valve 37 is in the closed state, so that the outflow passage in the second throttle state. The flow area is defined. The throttle area, which is the flow path area throttled by the second out orifice 37d, is defined wider than the first out orifice 38c formed in the third valve 38. That is, the second out orifice 37d is an orifice having a larger diameter than the first out orifice 38c.

The third valve 38 is formed of a metal material or the like into a two-stage columnar shape. The second valve 37 and the third valve 38 are arranged in series in the pressure control chamber 43. The third valve 38 has a disc portion 38b and a cylindrical portion 38a. The disk portion 38 b is formed with a larger diameter than the through hole 37 a of the second valve 37. On the other hand, the cylindrical portion 38 a is formed with a smaller diameter than the through hole 37 a of the second valve 37. The column part 38a protrudes from the disk part 38b in the column shape along the axial direction. The length of the cylindrical portion 38 a in the axial direction is longer than the length of the through hole 37 a of the second valve 37. The cylindrical portion 38a is guided in the axial direction by the inner wall of the through hole 37a of the second valve 37, and can be displaced in the axial direction. The disk part 38 b is a part that comes into contact with the lower end side contact part 37 c of the second valve 37.

The third valve 38 is disposed on the inner peripheral side of the cylinder 49 so as to be capable of reciprocating displacement along the axial direction of the valve body 31. A space between the third valve 38 and the valve pressure receiving surface 61 is substantially the pressure control chamber 43. The third valve 38 is urged toward the first valve chamber 45 with respect to the cylinder 49 by a third valve spring 55. A first out orifice 38 c is formed in the third valve 38. The first out orifice 38c penetrates the disk portion 38b of the third valve 38 in the plate thickness direction, extends part of the cylindrical portion 38a in the axial direction, and part of the insertion hole 38e extending to the side surface portion of the cylindrical portion 38a. Is formed. The insertion hole 38 e of the third valve 38 is a passage that communicates the pressure control chamber 43 and the first valve chamber 45. The first out orifice 38 c restricts the flow rate of fuel flowing from the pressure control chamber 43 to the first valve chamber 45 in a state where the second valve 37 blocks the in orifice 48 of the inflow channel 41.

The first valve 35 is formed in a bowl shape with a metal material or the like. The first valve 35 is disposed in the first valve chamber 45. The first valve 35 can be displaced in the first valve chamber 45 along the axial direction. The first valve 35 is urged toward the drive portion accommodation chamber 46 with respect to the upper end side contact portion 37b of the second valve 37 by a first valve spring 56 formed in a coil spring shape.

A pilot face portion 73 is formed on the first valve 35. The pilot face portion 73 is formed on the upper end surface of the first valve 35 that faces the downstream communication passage 53. The pilot face portion 73 is formed in a flat annular shape. The pilot face portion 73 comes into contact with the first seat portion 54 by the elastic force of the first valve spring 56. The pilot face portion 73 is pressed against the first seat portion 54 by the biasing force of the first valve spring 56 and the fuel pressure difference between the first valve chamber 45 and the low pressure passage 42. The seating of the pilot face portion 73 on the first seat portion 54 causes the first valve 35 to be closed.

The first valve 35 uses the distance displaced in the axial direction when the driving unit 33 generates the first driving force as the first lift amount, and in the axial direction when the driving unit 33 generates the second driving force. The displacement distance is defined as the second lift amount. The first lift amount is longer than the second lift amount.

In the first valve 35, the second valve 37, and the third valve 38, the direction from the pressure control chamber 43 toward the first valve chamber 45 and the drive unit storage chamber 46 along the axial direction is the valve closing direction, and along the axial direction. Thus, the direction from the drive unit housing chamber 46 to the pressure control chamber 43 is the valve opening direction. When the drive unit 33 does not generate a driving force, the low pressure flow path 42 is closed by the seating of the first valve 35 on the valve body 31. A valve opening gap 74 is formed between the first valve 35 in the valve closing position and the third valve 38 in the valve closing position. The valve opening gap 74 functions as a space that allows displacement in the valve opening direction only by the first valve 35.

Next, details of the injection operation of the fuel injection device 100 will be described with reference to FIGS. As shown in FIG. 3, the application of the drive voltage from the engine control device 17 to the drive unit 33 is interrupted before the start of injection. Therefore, the drive unit 33 does not substantially generate forces such as the first drive force and the second drive force. Therefore, the first valve 35 is pressed against the first seat portion 54 by the elastic force of the first valve spring 56. The second valve 37 is pressed against the wall surface around the opening of the inflow channel 41 by the elastic force of the third valve spring 55. For this reason, the pilot face portion 73 of the first valve 35 is brought into contact with the first seat portion 54, and the upper end side contact portion 37b of the second valve 37 is brought into contact with the second seat portion 50 to be stationary. is doing. A valve opening gap 74 is formed between the first valve 35 and the third valve 38. Since both the first valve 35 and the second valve 37 are in the closed state, the fuel pressure in the first valve chamber 45 has risen to substantially the same level as the fuel pressure in the pressure control chamber 43. In the above state, the nozzle needle 32 is stationary at the valve closing position where the face portion 62 is in contact with the seat portion 39.

First, the low-speed valve opening operation will be described. As shown in FIG. 4, in the low speed valve opening operation, application of the drive voltage from the engine control device 17 to the drive unit 33 is started. As a result, the drive unit 33 generates the first drive force. The engine control device 17 applies driving to the drive unit 33 so that a first driving force that is greater than the opening force of the first valve 35 and does not displace the third valve 38 acts on the first valve 35. Control the voltage.

When the drive unit 33 generates the first driving force, the second drive transmission pin 71 is displaced over the first lift amount. The first valve 35 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the first lift amount. In addition, the first valve 35 contacts the tip of the cylindrical portion 38 a of the third valve 38 so that the third valve 38 is not separated from the second valve 37. Due to the displacement of the first valve 35 in the valve opening direction, the valve opening gap 74 disappears.

By opening the first valve 35 as described above, the pressure control chamber 43 and the low-pressure flow path 42 are switched from the shut-off state to the communication state as shown in the first lift position in FIG. As a result, the high pressure fuel in the pressure control chamber 43 flows in the order of the first out orifice 38 c of the third valve 38 and the first valve chamber 45, and is discharged to the low pressure passage 42.

At this time, the flow area of the outflow flow path is defined by the throttle area of the first out orifice 38c which is smaller than the pilot opening area of the first valve 35. Therefore, the outflow passage is in the first throttle state in which the outflow flow rate of the fuel from the pressure control chamber 43 to the low pressure passage 42 is limited by the first out orifice 38c.

The pilot opening area is a channel area between the first seat portion 54 and the pilot face portion 73. In order to enable flow control by the first out orifice 38c, the valve opening gap 74 is defined in advance so that the pilot opening area is larger than the throttle area of the first out orifice 38c.

In the first throttle state described above, the third valve spring 55 urges the second valve 37 and the third valve 38 toward the first valve 35 in the valve closing direction, thereby opening the second valve 37 to the valve. Do not leave the body 31. As a result, the first valve 35 is pressed against the tip of the cylindrical portion 38 a of the third valve 38 and can be stationary while being sandwiched between the second drive transmission pin 71 and the first valve 35. In addition, since the driving force generated by the driving unit 33 is maintained at the first driving force, the closed state of the second valve 37 in the first throttle state is maintained.

Further, after the first valve 35 is lifted, the second valve 37 remains in the pressure control chamber 43 until the fuel flows out from the pressure control chamber 43 to the first valve chamber 45 and the pressure in the pressure control chamber 43 decreases to a predetermined pressure. The seated state is maintained by the pressure of. In other words, even if the first valve 35 opens and the pressure in the pressure control chamber 43 decreases, there is a time lag until the second valve 37 opens.

The fuel pressure in the first valve chamber 45 and the pressure control chamber 43 gradually decreases due to the outflow of fuel through the outflow passage in the first throttle state. As a result, the nozzle needle 32 is displaced in the valve opening direction while being gradually accelerated toward the pressure control chamber 43 by the pressure of the high-pressure fuel acting on the face portion 62. The fuel injection from the nozzle hole 30 is started by opening the main valve portion as described above.

In other words, the operation of the first lift position is such that the first valve 35 is opened by the first driving force, and only the first valve 35 is opened by stopping the first valve 35 when it contacts the third valve 38. It becomes a state. As a result, the fuel in the first valve chamber 45 flows out into the low pressure passage 42, and the fuel in the pressure control chamber 43 passes through the first out orifice 38c as the pressure in the first valve chamber 45 decreases. It flows out into one valve chamber 45. Further, due to the pressure drop in the first valve chamber 45, the second valve 37 and the third valve 38 receive pressure on the side closing the in-orifice 48 and the second out-orifice 37d, respectively, and close them. Accordingly, the fuel enters and exits the pressure control chamber 43 only from the first out orifice 38c, whereby the pressure in the pressure control chamber 43 decreases, and the nozzle needle 32 opens when a certain pressure is reached. At this time, the valve opening speed is defined by the flow rate of the first orifice.

Next, the high speed valve opening operation will be described. In the high-speed valve opening operation, the drive voltage applied from the engine control device 17 to the drive unit 33 is increased. As a result, the drive unit 33 generates a second driving force that exceeds the opening force of the third valve 38. The engine control device 17 controls the drive voltage applied to the drive unit 33 so that the generation of the second drive force larger than the valve opening force of the third valve 38 is maintained.

When the drive unit 33 generates the second driving force, the second drive transmission pin 71 is displaced over the second lift amount. The first valve 35 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the second lift amount. Further, due to the displacement of the first valve 35, the first valve 35 comes into contact with the cylindrical portion 38 a of the third valve 38, and the cylindrical portion 38 a of the third valve 38 is pushed by the first valve 35 and displaced in the valve opening direction. As a result, the disk portion 38 b of the third valve 38 is separated from the lower end side contact portion 37 c of the second valve 37.

When the third valve 38 is opened as described above, the fuel in the pressure control chamber 43 flows from the lower end side contact portion 37c of the second valve 37 and the disc portion 38b of the third valve 38 as in the second lift position of FIG. To the bypass passage 75, the second out orifice 37d, and the first valve chamber 45 in this order. The high-pressure fuel in the pressure control chamber 43 also flows through the first out orifice 38 c of the third valve 38 and the first valve chamber 45 in this order, and is discharged to the low-pressure channel 42. As a result, the configuration that regulates the flow passage area of the outflow passage and restricts the outflow flow rate of the fuel is switched from the first out orifice 38c to the first out orifice 38c and the second out orifice 37d. Since the throttle area is larger by the second out orifice 37d than the first out orifice 38c, the flow area of the outflow channel in the second throttle state is larger than that in the first throttle state. As a result, the flow rate of the fuel flowing out from the pressure control chamber 43 in the second throttle state increases more than in the first throttle state.

Similarly, after the first valve body is lifted, the second valve body is kept in pressure until the fuel flows out from the pressure control chamber 43 to the first valve chamber 45 and the pressure in the pressure control chamber 43 decreases to a predetermined pressure. The seated state is maintained by the pressure in the control chamber 43.

Both the opening area of the bypass passage 75 and the pilot opening area of the first valve 35 are larger than the sum of the throttle areas of the first out orifice 38c and the second out orifice 37d. In order to enable flow rate control in the second throttle state, it is defined in advance.

The fuel pressure in the first valve chamber 45 and the pressure control chamber 43 drops significantly due to the outflow of fuel whose flow rate is controlled by the second out orifice 37d. As a result, the nozzle needle 32 accelerates in the valve opening direction, and rapidly expands the gap between the seat portion 39 and the face portion 62. As described above, the flow area of the high-pressure flow path 40 connected to the injection hole 30 is increased, so that the fuel injection amount injected from the injection hole 30 is increased. As a result, a clear change occurs in the characteristics of the injection amount (injection rate) of the fuel injected from the injection hole 30 per unit time.

In other words, the operation of the second lift position is such that the first valve 35 is opened by the second driving force, the third valve 38 is further opened, and the first valve 35 is opened via the second out orifice 37d of the second valve 37. The valve chamber 45 and the pressure control chamber 43 communicate with each other. Since the second valve 37 receives a pressure difference between the pressure control chamber 43 and the first valve chamber 45, the in-orifice 48 is closed. Accordingly, the fuel enters and exits the pressure control chamber 43 and flows out from the first out orifice 38c and the second out orifice 37d, and the valve opening speed at this time is the total flow rate of the first out orifice 38c and the second out orifice 37d. It is prescribed by. Thus, the valve opening speed can be switched by switching control between the first driving force and the second driving force.

Next, the valve closing operation will be described. During the valve closing operation, the application of the drive voltage from the engine control device 17 to the drive unit 33 is interrupted. Then, the driving force of the drive unit 33 is less than the opening force of each of the first valve 35 and the third valve 38 and eventually disappears. As described above, the first valve 35 and the third valve 38 are displaced toward the valve closing direction by the elastic force of the first valve spring 56 or the third valve spring 55 and the fuel pressure. Then, the pilot face portion 73 and the disc portion 38b of the third valve 38 return to the closed state in which the first seat portion 54 and the lower end side abutting portion 37c of the second valve 37 are abutted. As a result, the pressure control chamber 43 and the low-pressure channel 42 are switched from the communication state to the cutoff state, and the outflow channel returns to the closed state.

On the other hand, when the first valve 35 is seated on the valve body 31 from the lifted state, the second valve 37 is separated due to the pressure difference between the pressure control chamber 43 and the inflow channel 41. In other words, the second valve 37 is pushed down by the fuel pressure of the high-pressure fuel flowing from the inflow passage 41. As a result, the high-pressure fuel that has passed through the in-orifice 48 flows into the pressure control chamber 43 and the first valve chamber 45. Thereby, each fuel pressure in the first valve chamber 45 and the pressure control chamber 43 is recovered integrally. As a result, the nozzle needle 32 is pushed down by the fuel pressure in the pressure control chamber 43 and returns to the state where the face portion 62 is brought into contact with the seat portion 39 at the valve closing position. The fuel injection from the nozzle hole 30 is interrupted by closing the main valve portion.

In other words, when the applied voltage is lowered after opening the first valve 35, the first valve 35 closes the low pressure flow path 42 by the first valve spring 56, and the third valve 38 is for the third valve. The second out orifice 37d is closed by the spring 55. Immediately after the first valve 35 and the third valve 38 are closed, the second valve 37 and the third valve 38 close the in-orifice 48 and the second out-orifice 37d, respectively, due to the pressure difference between the first valve chamber 45 and the pressure control chamber 43. To do. As a result, fuel flows from the pressure control chamber 43 into the first valve chamber 45 through the first out orifice 38c. As a result, the pressure in the first valve chamber 45 increases, and the pressure difference between the first valve chamber 45 and the pressure control chamber 43 decreases. Since the pressure in the pressure control chamber 43 is lower than that of the inflow channel 41 in the valve open state, the second valve 37 is opened due to the high pressure from the in-orifice 48 when the pressure difference between the first valve chamber 45 and the pressure control chamber 43 decreases. The fuel flows into the pressure control chamber 43. As a result, the nozzle needle 32 is closed.

In the first embodiment described so far, the flow area of the outflow flow path is switched by the switching valve mechanism 36 due to an increase in the generated drive force of the drive unit 33 from the first drive force to the second drive force. As described above, the displacement speed of the nozzle needle 32 is clearly changed by changing the pressure drop mode of the pressure control chamber 43. Therefore, the passage area rapidly increases in the orifice portion between the face portion 62 and the seat portion 39 through which the high-pressure fuel supplied to the injection hole 30 passes. As a result, the injection amount injected from the nozzle hole 30 per unit time also clearly changes before and after the driving force is switched by the driving unit 33. Therefore, the fuel injection device 100 can change the injection rate characteristic of the fuel injection by controlling the driving force generated by the single drive unit 33.

In the first embodiment, when the first valve 35 is in the first lift amount position and the outflow channel is in the first throttle state, the first valve 35 that is separated from the valve body 31 is the third valve. The third valve 38 is brought into contact with the third valve 38 so as not to separate the seat 38. Since the position of the first valve 35 is held by contact with the third valve 38, the flow area of the outflow passage in the first throttled state, and hence the amount of fuel outflow from the pressure control chamber 43, is stable. Become. In the present embodiment, the position of the first lift amount is also referred to as a first lift position.

Further, when the first valve 35 is at the second lift amount position and the outflow channel is in the second throttle state, the third valve 38 is displaced by the pressing by the first valve 35 and the third valve 38 is The two valves 37 are separated from each other. In this way, the position of the third valve 38 is held by the pressing of the first valve 35, so that the flow area of the outflow flow path in the second throttled state, and hence the amount of fuel discharged from the pressure control chamber 43 is also stable. It becomes. In the present embodiment, the position of the second lift amount is also referred to as a second lift position.

Thus, the switching valve mechanism 36 can switch the channel area of the outflow channel by adjusting the lift amount of the first valve 35. The lift amount of the first valve 35 can be controlled by one drive unit 33. Therefore, since the drive part 33 should just be the structure which controls the lift amount of one 1st valve | bulb 35, the drive part 33 can suppress enlargement.

Furthermore, the drive unit 33 of the first embodiment switches between the first throttle state and the second throttle state of the outflow channel not by the lift amount of the second drive transmission pin 71 but by the generated driving force of the drive unit 33. Yes. With the above configuration, the positions of the first valve 35 and the third valve 38 can be maintained even if the driving force varies to some extent in the first throttle state and the second throttle state. Therefore, since the highly accurate control of the lift amount of the second drive transmission pin 71 is not necessarily required, the control of the drive unit 33 can be simplified. Further, the dimensional accuracy required for each member can be relaxed.

In addition, in the first embodiment, in each of the first throttle state and the second throttle state, the first out orifice 38c and the second out orifice 37d, which are throttle holes provided in a specific member, The road area is specified. As described above, if the flow path area is not defined by the gap between the plurality of members, the variation in the flow rate of the fuel flowing through the outflow flow path in each throttled state is further reduced.

Furthermore, in the switching valve mechanism 36 of the first embodiment, a valve opening gap 74 is formed as a space that allows a stroke in the valve opening direction of the first valve 35. Therefore, the fuel injection device 100 can displace the first valve 35 and the third valve 38 in the valve opening direction at different timings by a simple linear operation of the single drive unit 33.

Furthermore, in the first embodiment, after the first valve 35 is lifted, the second valve is maintained until the fuel flows out from the pressure control chamber 43 to the first valve chamber 45 and the pressure in the pressure control chamber 43 decreases to a predetermined pressure. 37 maintains the seated state by the pressure of the pressure control chamber 43. As a result, the high pressure fuel can be prevented from flowing into the pressure control chamber 43 as soon as the first valve 35 is lifted. Therefore, the time for injecting fuel from the nozzle hole 30 can be secured.

Further, in the first embodiment, when the first valve 35 is seated on the valve body 31 from the lifted state, the second valve 37 is separated due to the pressure difference between the pressure control chamber 43 and the high-pressure flow path 40. Thus, when the fuel injection from the nozzle hole 30 is completed, the pressure control chamber 43 and the first valve chamber 45 can be filled with high-pressure fuel. Therefore, preparation for the next injection can be performed quickly.

Furthermore, in 1st Embodiment, when the 1st valve | bulb 35 starts a lift and is arrange | positioned in the position of 1st lift amount, after the 1st valve | bulb 35 lifts, the pressure of the pressure control chamber 43 falls to predetermined pressure. Until then, the third valve 38 is seated on the second valve 37 with the pressure of the pressure control chamber 43. This maintains the state where the second out orifice 37d of the second valve 37 is closed. Since the 2nd out orifice 37d is obstruct | occluded, in the case of 1st lift amount, it can be set as the 1st throttling state. Therefore, the first aperture state can be maintained without complicated driving.

Furthermore, in the first embodiment, the second valve 37 and the third valve 38 are arranged in the pressure control chamber 43. Since the second valve 37 is configured to partition a part of the first valve chamber 45, the volume of the pressure control chamber 43 contributing to the valve opening response and the insertion hole 38e of the third valve 38 contributing to the valve closing response. And the total volume of the first valve chamber 45 can be reduced. As a result, high responsiveness can be realized.

In the first embodiment, the high-pressure channel 40 corresponds to a supply channel, and the nozzle needle 32 corresponds to a valve member. The first valve 35 corresponds to the first valve body, the second valve 37 corresponds to the second valve body, and the third valve 38 corresponds to the third valve body. Further, the first valve chamber 45 corresponds to a switching chamber, the first out orifice 38c corresponds to a part of the insertion hole 35e of the first valve 35, and the second out orifice 37d corresponds to the insertion hole 37e of the second valve 37. Corresponds to a part of

(Second Embodiment)
Next, a second embodiment of the present disclosure will be described with reference to FIGS. 5 and 6. In the present embodiment, the configurations of the first valve 352 and the third valve 382 are different from those of the first embodiment.

The first valve 352 is formed of a metal material or the like into a two-stage columnar shape. The first valve 352 has a disk part 35b and a cylindrical part 35a. The disc part 35 b is formed with a larger diameter than the through hole 37 a of the second valve 37. On the other hand, the cylindrical portion 35 a is formed with a smaller diameter than the through hole 37 a of the second valve 37. The column part 35a protrudes from the disk part 35b in the column shape along the axial direction. The length of the cylindrical portion 35 a in the axial direction is longer than the length of the through hole 37 a of the second valve 37. The cylindrical portion 35a is guided in the axial direction by the inner wall of the through hole 37a of the second valve 37, and can be displaced in the axial direction. A first valve spring 56 is disposed between the disk portion 35 b and the upper end side contact portion 37 b of the second valve 37.

Further, the first valve 352 is formed with an insertion hole 35e for communicating the first valve chamber 45 and the pressure control chamber 43. A first out orifice 38 c is formed in a part of the insertion hole 35 e of the first valve 352. The insertion hole 35e of the first valve 352 has a portion extending in the axial direction of the cylindrical portion 35a of the first valve 352 and a portion extending in the radial direction of the cylindrical portion 35a. The first out orifice 38c is formed in a portion extending in the axial direction of the insertion hole 35e.

The third valve 382 is formed in a disk shape from a metal material or the like. The outer diameter of the third valve 382 is formed larger than the through hole 37 a of the second valve 37. In addition, an insertion hole 38e that penetrates the third valve 382 in the axial direction is formed in the center of the third valve 382 in the radial direction. The inner diameter of the insertion hole 38e of the third valve 382 is smaller than the outer diameter of the cylindrical portion 35a of the first valve 352. Further, the insertion hole 38 e of the third valve 382 has a smaller inner diameter than the through hole 37 a of the second valve 37. Therefore, the upper end side contact portion 38f of the third valve 382 becomes a portion where the tip of the cylindrical portion 35a of the first valve 352 contacts.

Next, the injection operation of the fuel injection device 100 will be described. As shown in FIG. 5, the pilot face portion 73 of the first valve 352 is brought into contact with the first seat portion 54 and the upper end side contact portion of the second valve 37 before the start of injection, as in the first embodiment. 37b is stationary at the valve closing position where the second seat portion 50 is brought into contact with the second seat portion 50. A valve opening gap 74 is formed between the cylindrical portion 35 a of the first valve 352 and the upper end side contact portion 38 f of the third valve 382.

First, the low-speed valve opening operation will be described. As shown in FIG. 6, in the low-speed valve opening operation, the application of the drive voltage from the engine control device 17 to the drive unit 33 is started as in the first embodiment. When the drive unit 33 generates the first driving force, the second drive transmission pin 71 is displaced over the first lift amount. The first valve 352 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the first lift amount. In addition, the tip of the cylindrical portion 35a of the first valve 352 contacts the upper end side contact portion 38f of the third valve 382 so that the third valve 382 is not separated from the second valve 37. Due to such displacement of the first valve 352 in the valve opening direction, the valve opening gap 74 disappears.

By opening the first valve 352 as described above, the pressure control chamber 43 and the low-pressure flow path 42 are switched from the shut-off state to the communication state as shown in the first lift position in FIG. As a result, the high pressure fuel in the pressure control chamber 43 flows through the insertion hole 38e of the third valve 382, the first out orifice 38c of the first valve 352, and the first valve chamber 45 in this order, and is discharged to the low pressure passage 42. . As a result, the outflow passage is in a first throttle state in which the outflow flow rate of fuel from the pressure control chamber 43 to the low pressure passage 42 is limited by the first out orifice 38c.

Next, the high speed valve opening operation will be described. In the high-speed valve opening operation, the drive unit 33 generates a second driving force that exceeds the valve opening force of the third valve 382 as in the first embodiment.

When the drive unit 33 generates the second driving force, the second drive transmission pin 71 is displaced over the second lift amount. The first valve 352 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the second lift amount. Further, due to the displacement of the first valve 352, the cylindrical portion 35a of the first valve 352 contacts the upper end side contact portion 38f of the third valve 382, and the first valve 352 pushes the third valve 382 in the valve opening direction. Displace. Thus, the third valve 382 is separated from the lower end side contact portion 37c of the second valve 37.

By opening the third valve 382 as described above, as shown in the second lift position of FIG. 6, the fuel in the pressure control chamber 43 is in contact with the lower end side contact portion 37 c of the second valve 37 and the upper end side of the third valve 382. The bypass passage 75 between the contact portion 38f, the second out orifice 37d of the second valve 37, and the first valve chamber 45 are sequentially circulated. The high pressure fuel in the pressure control chamber 43 also flows through the insertion hole 38e of the third valve 382, the first out orifice 38c of the first valve 352, and the first valve chamber 45 in this order, and is discharged to the low pressure flow path 42. As a result, the flow path area of the outflow flow path becomes the second throttled state that is larger than the first throttled state.

Next, the valve closing operation will be described. During the valve closing operation, the driving force of the driving unit 33 disappears as in the first embodiment. As described above, the first valve 352 and the third valve 382 are displaced in the valve closing direction by the elastic force of the first valve spring 56 or the third valve spring 55 and the fuel pressure. As a result, the valve face is returned to the closed state in which the pilot face portion 73 and the upper end side contact portion 38f of the third valve 382 are brought into contact with the first seat portion 54 and the lower end side contact portion 37c of the second valve 37. As a result, the pressure control chamber 43 and the low-pressure channel 42 are switched from the communication state to the cutoff state, and the outflow channel returns to the closed state.

Thus, even in the configuration in which the first out orifice 38c is arranged in the first valve 352, the switching control between the first throttle state and the second throttle state can be performed as in the first embodiment described above. it can. As a result, the same operations and effects as in the first embodiment can be achieved.

(Third embodiment)
Next, a third embodiment of the present disclosure will be described with reference to FIGS. 7 and 8. In the present embodiment, the configuration of the first valve chamber 453 is different from that of the first embodiment. The first valve chamber 453 is partitioned by the valve body 31. A first placement portion 76 is formed on the partition wall that partitions the first valve chamber 453 together with the first seat portion 54. The lower end of the first valve spring 56 is placed on the first placement portion 76.

Further, the valve body 31 is formed with a communication channel 77 that allows the pressure control chamber 43 and the first valve chamber 453 to communicate with each other. The end of the communication channel 77 on the first valve chamber 453 side is formed outside the first valve spring 56. The end of the communication channel 77 on the pressure control chamber 43 side is formed at a position facing the end of the cylindrical portion 38 a of the third valve 38, that is, a position facing the through hole 37 a of the second valve 37.

The switching valve mechanism 36 further includes a third drive transmission pin 78. The third drive transmission pin 78 is provided between the first valve 35 and the third valve 38. The third drive transmission pin 78 is cylindrical, and transmits the downward displacement of the first valve 35 to the third valve 38. The valve body 31 is formed with a guide hole 79 through which the third drive transmission pin 78 is inserted to guide the third drive transmission pin 78. The guide hole 79 communicates with the pressure control chamber 43 and the first valve chamber 453 and is formed to be coaxial with the first valve 35. The outer diameter of the third drive transmission pin 78 is smaller than the outer diameter of the cylindrical portion 38 a of the third valve 38 and can be displaced in the through hole 37 a of the second valve 37.

The insertion hole 37e of the second valve 37 communicates the lower end side contact portion 37c and the inside of the through hole 37a of the second valve 37. Thus, even when the second valve 37 is seated on the second seat portion 50, the fuel that has flowed into the insertion hole 37 e from the lower end side contact portion 37 c side is in the through hole 37 a of the second valve 37. To leak.

Next, the injection operation of the fuel injection device 100 will be described. As shown in FIG. 7, the pilot face portion 73 of the first valve 35 is brought into contact with the first seat portion 54 and the upper end side contact portion of the second valve 37 before the start of injection, as in the first embodiment. 37b is stationary at the valve closing position where the second seat portion 50 is brought into contact with the second seat portion 50. A valve opening gap 74 is formed between the first valve 35 and the third drive transmission pin 78.

First, the low-speed valve opening operation will be described. As shown in FIG. 8, in the low-speed valve opening operation, application of the drive voltage from the engine control device 17 to the drive unit 33 is started as in the first embodiment. When the drive unit 33 generates the first driving force, the second drive transmission pin 71 is displaced over the first lift amount. The first valve 35 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the first lift amount. In addition, the first valve 35 contacts the third drive transmission pin 78 so that the third valve 38 is not separated from the second valve 37. Due to the displacement of the first valve 35 in the valve opening direction, the valve opening gap 74 disappears.

By opening the first valve 35 as described above, the pressure control chamber 43 and the low-pressure flow path 42 are switched from the shut-off state to the communication state as shown in the first lift position of FIG. As a result, the high-pressure fuel in the pressure control chamber 43 flows in the order of the first out-orifice 38c of the third valve 38, the through hole 37a of the second valve 37, the communication channel 77, and the first valve chamber 453. 42 is discharged. As a result, the outflow passage is in a first throttle state in which the outflow flow rate of fuel from the pressure control chamber 43 to the low pressure passage 42 is limited by the first out orifice 38c.

Next, the high speed valve opening operation will be described. In the high-speed valve opening operation, the drive unit 33 generates a second driving force that exceeds the valve opening force of the third valve 38 as in the first embodiment.

When the drive unit 33 generates the second driving force, the second drive transmission pin 71 is displaced over the second lift amount. The first valve 35 pushed down by the second drive transmission pin 71 separates the pilot face portion 73 from the first seat portion 54 by displacement in the valve opening direction over the second lift amount. Further, due to the displacement of the first valve 35, the first valve 35 contacts the third drive transmission pin 78, and the third valve 38 is pushed together with the third drive transmission pin 78 by the first valve 35 to displace in the valve opening direction. . As a result, the third valve 38 is separated from the lower end side contact portion 37 c of the second valve 37.

By opening the third valve 38 as described above, as shown in the second lift position of FIG. 8, the fuel in the pressure control chamber 43 flows into the lower end side contact portion 37 c of the second valve 37 and the disc portion 38 b of the third valve 38. , The second out-orifice 37d of the second valve 37, the through-hole 37a of the second valve 37, the communication channel 77 and the first valve chamber 453 in this order. The high pressure fuel in the pressure control chamber 43 also flows in the order of the first out orifice 38 c of the third valve 38, the through hole 37 a of the second valve 37, the communication channel 77 and the first valve chamber 453, and the low pressure channel 42. Is discharged. As a result, the flow path area of the outflow flow path becomes the second throttled state that is larger than the first throttled state.

Next, the valve closing operation will be described. During the valve closing operation, the driving force of the driving unit 33 disappears as in the first embodiment. As described above, the first valve 35 and the third valve 38 are displaced toward the valve closing direction by the elastic force of the first valve spring 56 or the third valve spring 55 and the fuel pressure. As a result, the pilot face portion 73 and the disk portion 38b of the third valve 38 return to the closed state in which they are brought into contact with the first seat portion 54 and the lower end side contact portion 37c of the second valve 37. As a result, the pressure control chamber 43 and the low-pressure channel 42 are switched from the communication state to the cutoff state, and the outflow channel returns to the closed state.

As described above, even when the first valve chamber 453 is partitioned by the valve body 31, the first throttle state and the second throttle state can be switched and controlled as in the first embodiment described above. As a result, the same operations and effects as in the first embodiment can be achieved.

Also, since the first valve spring 56 is placed on the first placement portion 76, the elastic force of the first valve spring 56 and the third valve spring 55 can be set independently. This facilitates selection of the first valve spring 56 and the third valve spring 55.

(Other embodiments)
The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

The structure of the above-described embodiment is merely an example, and the scope of the present disclosure is not limited to the scope of these descriptions. The scope of the present disclosure is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

In the first embodiment described above, the channel area of the outflow channel in each throttled state is defined by each orifice formed in a hole shape. However, the channel area of the outflow channel in each throttled state may be defined by a gap provided between the two members.

In the first embodiment described above, the fuel injection device 100 that injects light oil as fuel is realized, but the present invention is also applicable to a fuel injection device that injects fuel other than light oil, for example, liquefied gas fuel such as dimethyl ether.

Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims (6)

1. A fuel injection device (100) for injecting fuel from an injection hole (30),
   The injection hole, a supply flow path (40) for supplying fuel to the injection hole, a pressure control chamber (43) into which a part of the fuel flowing through the supply flow path flows, and the fuel in the pressure control chamber at low pressure side A valve body (31) in which an outflow channel (42) is formed to flow into
   A valve member (32) for opening and closing the nozzle hole by relative displacement with respect to the valve body due to a change in fuel pressure in the pressure control chamber;
   At least a part of the first valve body (35, 352) disposed in the switching chamber (45, 453) in the outflow passage, the second valve body (37) disposed in the pressure control chamber, and A switching valve mechanism (36) having a third valve body (38, 382) disposed in the pressure control chamber and switching the flow passage area of the outflow passage;
   The first valve body is lifted by applying a driving force to the first valve body in order to switch the flow passage area by the switching valve mechanism, and the lift amount of the first valve body is set to a first amount. A drive unit (33) that performs switching control to a lift amount or a second lift amount larger than the first lift amount,
   The switching chamber communicates with the pressure control chamber;
   The second valve body and the third valve body are formed with insertion holes (37e, 38e) that are part of the outflow channel,
   The switching valve mechanism is
   When the first valve body is not lifted, the first valve body is seated on the valve body to close the outflow channel,
   When the first valve body is in the position of the first lift amount, the first valve body is separated from the valve body, and the second valve body and the third valve body are not separated. By being in position, the fuel passes through the insertion hole (38e) of the third valve body and restricts the outflow channel to the first throttle state,
   When the first valve body is in the position of the second lift amount, the first valve body is separated from the valve body, and the first valve body is pressed against the third valve body by the first valve body. Since the three-valve element is separated from the second valve element, fuel passes through the insertion hole (37e) of the second valve element, and the outflow passage is different from the first throttle state. A fuel injection device that restricts to a second throttle state with different road areas.
2. The second valve body is seated to block communication between the supply flow path and the pressure control chamber, and is separated from the supply flow path and pressure control chamber to communicate with each other.
   After the first valve body is lifted, the second valve body is in the pressure control chamber until the fuel flows out from the pressure control chamber to the switching chamber and the pressure in the pressure control chamber decreases to a predetermined pressure. The fuel injection device according to claim 1, wherein the seated state is maintained by pressure.
3. The second valve body is seated to block communication between the supply flow path and the pressure control chamber, and is separated from the supply flow path and pressure control chamber to communicate with each other.
   3. The second valve body according to claim 1, wherein when the first valve body is seated on the valve body from a lifted state, the second valve body is separated by a pressure difference between the pressure control chamber and the supply flow path. Fuel injection device.
4. The second valve body is seated to block communication between the supply flow path and the pressure control chamber, and is separated from the supply flow path and pressure control chamber to communicate with each other.
   When the first valve body starts to be lifted and is disposed at the position of the first lift amount, the fuel flows out from the pressure control chamber to the switching chamber after the first valve body has been lifted. Until the pressure in the pressure control chamber drops to a predetermined pressure, the third valve body is seated on the second valve body by the pressure in the pressure control chamber and closes the insertion hole of the second valve body. The fuel injection device according to any one of claims 1 to 3, wherein the state is maintained.
5. The fuel injection device according to any one of claims 1 to 4, wherein the second throttle state is a throttle state having a larger flow path area than the first throttle state.
6. 6. The fuel injection device according to claim 1, wherein a flow passage area of the insertion hole of the second valve body is larger than a flow passage area of the insertion hole of the third valve body.
   
   

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