JP2018155198A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device having a control member which enables generation of high pressure while inhibiting change of injection performance.SOLUTION: In a fuel injection device 100, a path connecting a circumference groove 81 and a communication groove 82 with an upstream side communication passage 55 is provided at a lower seat part 47b. The structure causes a fuel flowing from the lower seat part 47b to flow into the upstream side communication passage 55 through the circumference groove 81 and the communication groove 82 formed at the lower seat part 47b. The circumference groove 81 and the communication groove 82 are a path which bypasses a valve spring 60. The fuel flowing from an intermediate passage 59 into an intermediate chamber 47 flows into the upstream side communication passage 55 through the path that is the circumference groove 81 and the communication groove 82.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel injection device that injects fuel.

  In a fuel injection device that uses a piezo element as an actuator and hydraulically controls a nozzle needle valve, there are demands for high pressure, reduced variation in injection amount, and no static leakage. In order to meet such a demand, for example, the fuel injection device described in Patent Document 1 has a static leakless structure in which there is no leakage that always flows through the sliding gap.

JP, 2006-53354, A

  In the fuel injection device described in Patent Document 1, the valve needle may be tilted in the assembled state due to a problem in processing accuracy of the valve needle and a positional deviation during the assembly. Further, when the valve needle is tilted and rotated by fluid force or the like when fuel flows into the intermediate chamber, the fuel passage area of the lower seat portion varies. In this case, since the amount of fuel flowing into the intermediate chamber changes, it is difficult to supply a stable injection amount.

  Further, as in Patent Document 1, a valve spring is provided around the valve needle. The high-pressure fuel that passes through the lower seat portion passes through the gap between the valve springs and flows into the pressure control chamber. Therefore, depending on the specifications of the valve spring, the clearance between the line of the valve spring becomes the constricted part, and due to individual differences of the valve spring, the assembly direction of the rotation direction of the valve spring, and the fluctuation between the dynamic line gap when the valve spring is activated There is a possibility that the injection performance will change.

  Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection device having a control member capable of increasing the pressure while suppressing a change in injection performance.

  The present invention employs the following technical means in order to achieve the aforementioned object.

The present invention is a fuel injection device (100) that injects fuel supplied through a fuel flow path (15) from a nozzle hole (44) and discharges part of the supplied fuel to a return flow path (16). And
A nozzle hole, a high-pressure channel (42) communicating with the fuel channel, a pressure control chamber (46) into which fuel supplied through the high-pressure channel flows, and a storage chamber (58) into which fuel supplied through the high-pressure channel flows An intermediate chamber (47) through which the fuel in the pressure control chamber flows out, an outflow passage (55) communicating the pressure control chamber and the intermediate chamber, an intermediate passage (59) communicating the storage chamber and the intermediate chamber, and the intermediate chamber A valve body (51) forming a discharge passage (56) for discharging fuel to the return flow path;
A valve body (50) that opens and closes the nozzle hole by being reciprocally displaced by pressure fluctuation in the pressure control chamber;
The pressure in the pressure control chamber is changed by switching between the first state in which the discharge passage is connected and the intermediate passage is blocked, and the second state in which the discharge passage is blocked and the intermediate passage is connected. A control member (54) for causing;
A control member spring (60) housed in the intermediate chamber, one end contacting the lower sheet portion of the intermediate chamber on the injection hole side, the other end contacting the control member, and urging the control member toward the counter injection hole side When,
A drive unit (52) for displacing the control member to the injection hole side or the counter injection hole side,
When the control member is brought into the first state by the drive unit, the fuel in the pressure control chamber flows out through at least the outflow passage, the intermediate chamber, and the discharge passage, the pressure in the pressure control chamber decreases, and the valve body is displaced and injected. When the hole is opened and the control member is set to the second state by the drive unit, fuel flows into the pressure control chamber via at least the high-pressure flow path, the pressure in the pressure control chamber rises, and the valve body is displaced. To close the nozzle hole,
The control member (54) contacts the lower sheet portion (47b) of the intermediate chamber in the first state to block the intermediate passage, and in the second state, the upper sheet portion (47a) of the intermediate chamber on the side opposite to the injection hole. ), The discharge passage is blocked, and the lower seat portion is located between the opening (59b) of the intermediate passage (59) and the opening (55a) of the outflow passage (55), and the opening of the intermediate passage. Is a fuel injection device in which a peripheral groove (81) surrounding the outer periphery and a communication groove (82) communicating the peripheral groove and the opening of the outflow passage are formed.

  According to the present invention, when the drive unit is driven and the control member is pressed toward the injection hole side, the control member is moved toward the injection hole side against the urging force on the counter injection hole side of the control member spring. Moving. When the drive unit stops, the control member is moved to the counter injection hole side by the control member spring. Accordingly, the control member is separated from the lower seat portion of the intermediate chamber, and the fuel from the storage chamber flows into the intermediate chamber via the intermediate passage. The fuel flowing in from the lower seat portion passes through the peripheral groove and the communication groove formed in the lower seat portion and flows into the outflow passage. The peripheral groove and the communication groove are paths that bypass the control member spring. Further, the peripheral groove and the communication groove are not affected by the cross-sectional area of the passage depending on the attitude of the control member. Accordingly, the fuel that has flowed into the intermediate chamber from the intermediate passage flows into the outflow passage through a path called a peripheral groove and a communication groove. As described above, since there is a path that is not affected by the posture of the control member and the shape of the spring for the control member, a change in the injection performance can be suppressed. Even if the pressure of the control member is affected by the increase in pressure, fluctuations in the flow rate can be suppressed by the peripheral grooves and the communication grooves. Therefore, according to the structure of this invention, it has tolerance also to the displacement of the control member by high pressure.

  In addition, the code | symbol in the bracket | parenthesis of each above-mentioned means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

The system diagram which shows a fuel supply system. Sectional drawing which simplifies and shows a fuel-injection apparatus. The figure for demonstrating operation | movement of a fuel-injection apparatus. The front view which shows a valve needle. The perspective view which expands and shows the lower sheet | seat part 47b. The top view which expands and shows the lower sheet | seat part 47b of 1st Example of 2nd Embodiment. The top view which expands and shows the lower sheet | seat part 47b of 2nd Example of 2nd Embodiment. The top view which expands and shows the lower sheet | seat part 47b of 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described using a plurality of embodiments 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 invention 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 a 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 12, a high-pressure fuel pump 13, a common rail 14, an engine control device 17, and a plurality of fuel injection devices 100.

  The feed pump 12 is a pump that pumps the fuel stored in the fuel tank 11 to the high-pressure fuel pump 13. The feed pump 12 is connected to the high-pressure fuel pump 13 by a fuel pipe 12a. The fuel tank 11 stores fuel such as light oil.

  The high pressure fuel pump 13 is driven by the output shaft of the diesel engine 20. The high-pressure fuel pump 13 is connected to the common rail 14 by a fuel pipe 13a. The high-pressure fuel pump 13 further boosts the fuel supplied by the feed pump 12 and supplies it to the common rail 14.

  The common rail 14 is connected to a plurality of fuel injection devices 100 via a fuel pipe 14a. In FIG. 1, one fuel injection device 100 is shown, and the illustration of the other fuel injection devices 100 is omitted. The fuel pipe 14 a forms a fuel flow path 15 that supplies fuel to each fuel injection device 100. The common rail 14 temporarily stores high-pressure fuel supplied from the high-pressure fuel pump 13 and distributes the fuel to each fuel injection device 100 while maintaining the pressure. The surplus fuel in the common rail 14 is discharged to the surplus fuel pipe 14b while being depressurized. The surplus fuel pipe 14 b forms a return flow path 16 that recirculates surplus fuel to the fuel tank 11.

  The engine control device 17 is a fuel injection control device, which is a microcomputer or a microcontroller including a processor as an arithmetic circuit, a RAM, and a rewritable nonvolatile storage medium, and a drive circuit that drives each fuel injection device 100. It is the structure containing these. 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 engine control device 17 acquires information from various sensors and controls each part. The engine control device 17 controls the pressure of the common rail 14 using, for example, a fuel pressure acquired from a pressure sensor that detects the pressure of the common rail 14.

  A fuel pipe 14 a and a return pipe 14 c are connected to the fuel injection device 100. 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 fuel flow path 15 into the combustion chamber 22 from the plurality of injection holes 44. The fuel injection device 100 includes a valve mechanism that controls fuel injection from the injection hole 44. The valve mechanism includes a valve needle 54 (see FIG. 2) that operates based on a drive signal from the engine control device 17 and a nozzle needle 50 that opens and closes the injection hole 44. The fuel injection device 100 uses a part of the fuel supplied through the fuel flow path 15 in order to open and close the injection hole 44. The fuel used to open and close the nozzle hole 44 is discharged to the return pipe 14c while being decompressed. The return pipe 14c and the surplus fuel pipe 14b form a return flow path 16 for returning the fuel that has not been used for combustion to the fuel tank 11.

  Next, the fuel injection device 100 will be described with reference to FIG. As shown in FIG. 2, the fuel injection device 100 includes a nozzle needle 50, a valve body 51, a drive unit 52, a control plate 53, and a valve needle 54.

  The valve body 51 is configured by combining a plurality of members such as a cylinder formed of a metal material. The valve body 51 includes a seat portion 41, a high pressure channel 42, an inflow channel 43, an injection hole 44, a low pressure channel 45, a pressure control chamber 46, an intermediate chamber 47, and a drive unit accommodation chamber 48.

  The injection hole 44 is formed at the distal end in the insertion direction of the valve body 51 inserted into the combustion chamber 22. The tip is formed in a conical or hemispherical shape. At least one nozzle hole 44 is provided radially from the inside to the outside of the valve body 51, in the present embodiment. High-pressure fuel is injected from each injection hole 44 toward the combustion chamber 22. The high-pressure fuel is atomized by passing through the nozzle hole 44, and is easily mixed with air. The seat portion 41 is formed in a conical shape inside the distal end portion of the valve body 51. The seat portion 41 faces the high-pressure channel 42 on the upstream side of the nozzle hole 44.

  The high-pressure channel 42 supplies high-pressure fuel supplied from the common rail 14 through the common rail 14 shown in FIG. The inflow channel 43 allows the high-pressure channel 42 and the pressure control chamber 46 to communicate with each other. The inflow channel 43 causes a part of the fuel flowing through the high-pressure channel 42 to flow into the pressure control chamber 46. The inflow channel 43 is provided with a main-in orifice 43a as an inflow orifice. The main-in orifice 43a limits the flow rate of fuel flowing from the high-pressure channel 42 to the pressure control chamber 46.

  The low pressure channel 45 extends along the high pressure channel 42 in the valve body 51. The low-pressure channel 45 is a part of a discharge passage through which the fuel (leak fuel) in the pressure control chamber 46 flows out to the surplus fuel pipe 14 b on the low-pressure side outside the fuel injection device 100. The discharge passage is constituted by a low-pressure passage 45, an intermediate chamber 47, an upstream communication passage 55, a downstream communication passage 56, and the like, which will be described later. The pressure of the fuel flowing through the low pressure channel 45 is lower than the pressure of the fuel in the pressure control chamber 46.

  The pressure control chamber 46 is provided inside the valve body 51 on the opposite side of the nozzle hole 44 with the nozzle needle 50 interposed therebetween. The pressure control chamber 46 is a cylindrical space that accommodates the control plate 53 therein and is partitioned by the cylinder 57 and the nozzle needle 50. High pressure fuel flows into the pressure control chamber 46 through the inflow passage 43. The fuel pressure in the pressure control chamber 46 varies depending on the inflow of high-pressure fuel from the inflow passage 43, the outflow of fuel to the intermediate chamber 47, and the inflow from the intermediate chamber 47. The nozzle needle 50 is reciprocated by the pressure fluctuation in the pressure control chamber 46.

  The intermediate chamber 47 is a space that accommodates the valve needle 54. The intermediate chamber 47 is located between the pressure control chamber 46 and the drive unit accommodation chamber 48. The axial direction of the intermediate chamber 47 is along the axial direction of the pressure control chamber 46 and the cylinder 57. An upstream communication path 55 is formed between the intermediate chamber 47 and the pressure control chamber 46. The fuel discharged from the pressure control chamber 46 flows into the intermediate chamber 47 through the upstream communication passage 55. The fuel pressure in the upstream communication passage 55 is substantially the same as the fuel pressure in the intermediate chamber 47.

  Further, a downstream communication path 56 is formed between the intermediate chamber 47 and the drive unit accommodation chamber 48. The downstream side communication passage 56 mainly causes the fuel discharged from the intermediate chamber 47 to flow through the low pressure passage 45. An intermediate passage 59 is formed between the intermediate chamber 47 and the needle storage chamber 58 in which the nozzle needle 50 is stored. The fuel supplied from the high-pressure channel 42 flows into the intermediate chamber 47 through the intermediate passage 59 through the needle housing chamber 58. Further, a sub-in orifice 59a is formed in the intermediate passage 59. The sub-in orifice 59a is a throttle portion that partially restricts the flow path area of the intermediate passage 59. The sub-in orifice 59a limits the flow rate of the fuel flowing out from the needle housing chamber 58 to the intermediate chamber 47 when the valve needle 54 is in a closed state.

  An upper sheet portion 47a, a lower sheet portion 47b, and a placement portion 47c are formed on a partition wall that partitions the intermediate chamber 47. The lower sheet portion 47 b is an annular region surrounding the periphery of the opening 59 b of the intermediate passage 59 in the partition wall of the intermediate chamber 47. The lower seat portion 47b is a region where the lower end side of the valve needle 54 is seated.

  The upper sheet portion 47 a is an annular region surrounding the periphery of the opening of the downstream communication passage 56 in the partition wall of the intermediate chamber 47. The upper seat portion 47a is a region where the upper end side of the valve needle 54 is seated. The placement portion 47 c is an area surrounding the lower sheet portion 47 b in the partition wall of the intermediate chamber 47. One end of a later-described valve spring 60 is placed on the placement portion 47c.

  The nozzle needle 50 is formed in a cylindrical shape as a whole by a metal material. The nozzle needle 50 is accommodated in the valve body 51. The nozzle needle 50 is urged toward the nozzle hole 44 by a coiled nozzle spring 61 in which a metal wire is wound spirally. The nozzle needle 50 has a valve pressure receiving surface 62 and a face portion 63. The nozzle needle 50 is reciprocally displaced in the axial direction along the inner peripheral wall surface of the cylinder 57 formed in a cylindrical shape by receiving the fuel pressure in the pressure control chamber 46 on the valve pressure receiving surface 62. The nozzle needle 50 is displaced relative to the valve body 51, so that the face portion 63 is separated from and seated on the seat portion 41. The face portion 63 forms a main valve portion that opens and closes the nozzle hole 44 together with the seat portion 41.

  The drive unit storage chamber 48 is a cylindrical space that stores the drive unit 52. The drive unit accommodation chamber 48 is filled with a part of the fuel discharged from the intermediate chamber 47. The axial direction of the drive unit accommodating chamber 48 is along the axial direction of the intermediate chamber 47. The drive unit accommodating chamber 48 and the intermediate chamber 47 are provided so as to be coaxial with each other.

  The drive unit 52 is accommodated in the drive unit accommodation chamber 48. The drive unit 52 displaces the valve needle 54 to the injection hole side or the counter injection hole side, and switches between the pressure control chamber 46 and the low pressure flow path 45 from the cutoff state to the communication state. The drive unit 52 can change the magnitude of the drive force to be generated based on the drive signal output from the engine control device 17, and can generate, for example, a two-stage drive force.

  The drive unit 52 includes a piezoelectric element laminate 64, a transmission mechanism 65, and the like. The piezoelectric element laminate 64 is a laminate in which, for example, layers called PZT (PbZrTiO3) and thin electrode layers are alternately stacked. An input driving signal output from the engine control device 17 is input to the piezoelectric element laminate 64. The piezoelectric element stacked body 64 expands and contracts along the axial direction of the drive unit accommodating chamber 48 due to a reverse piezoelectric effect that is a characteristic of the piezoelectric element, according to a voltage corresponding to a drive signal (hereinafter, “drive voltage”).

  The transmission mechanism 65 is a mechanism that transmits expansion / contraction of the piezoelectric element laminate 64. The transmission mechanism 65 includes a piezo piston 66, a valve cylinder 67, a valve piston 68, and a piston spring 69. The piezo piston 66 is formed in a cylindrical shape. The piezo piston 66 is in contact with the piezoelectric element laminate 64. The movement of the piezoelectric element laminate 64 that expands and contracts is input to the piezo piston 66. The piezo piston 66 and the valve piston 68 are accommodated in the valve cylinder 67 with a space therebetween. The space between the piezo piston 66 and the valve piston 68 is filled with fuel and functions as the oil tight chamber 70.

  The valve cylinder 67 is formed in a cylindrical shape and is fitted on the piezo piston 66 and the valve piston 68. The piston spring 69 is a metal spring that generates an elastic force in the axial direction. The piston spring 69 biases the valve piston 68 toward the valve needle 54 with respect to the valve cylinder 67.

  As a result, the displacement of the piezo piston 66 is transmitted to the valve piston 68 through the oil-tight chamber 70. The valve piston 68 is formed with a drive pin 71 that protrudes in a cylindrical shape toward the intermediate chamber 47. The drive pin 71 is inserted through the downstream communication path 56. The front end surface of the drive pin 71 is in contact with the valve needle 54.

  In this way, the drive unit 52 reciprocally displaces the drive pin 71 in the axial direction by transmitting the expansion and contraction of the piezoelectric element stack 64 along the axial direction by the transmission mechanism 65. As the drive voltage input to the drive unit 52 increases, the drive force input from the drive pin 71 to the valve needle 54, and hence the lift amount of the drive pin 71 and the valve needle 54, increases.

  The control plate 53 is formed in a disk shape from a metal material. The control plate 53 is disposed on the inner peripheral side of the cylinder 57 so as to be capable of reciprocating displacement along the axial direction of the valve body 51. A space between the control plate 53 and the valve pressure receiving surface 62 is substantially the pressure control chamber 46. The control plate 53 is urged toward the upstream communication path 55 with respect to the cylinder 57 by a control plate spring 72. The control plate 53 has a first out orifice 53a. The first out orifice 53a is formed in a through hole that penetrates the control plate 53 in the thickness direction. The through hole of the control plate 53 and the first out orifice 53 a function as a communication path that connects the upstream communication path 55 and the pressure control chamber 46. The first out orifice 53a limits the flow rate of fuel flowing from the pressure control chamber 46 to the upstream communication passage 55 and the intermediate chamber 47 in a state where the control plate 53 blocks the main in orifice 43a of the inflow passage 43. To do.

  Next, the valve needle 54 will be described. The valve needle 54 switches between a first state in which the downstream communication path 56 communicates and the intermediate passage 59 is blocked, and a second state in which the downstream communication path 56 is blocked and the intermediate path 59 communicates. It is a control member that varies the pressure in the pressure control chamber 46. The valve needle 54 is mushroom-shaped in this embodiment, and has a disk part 54a and a cylindrical part 54b. The disk part 54a has a larger diameter than the cylindrical part 54b. The cylindrical portion 54b has a larger dimension in the axial direction than the disk portion 54a. The upper surface of the disk part 54a is spherical. The tip of the cylindrical portion 54b is flat. When the driving unit 52 does not generate a driving force, the downstream communication path 56 is closed. On the other hand, when the driving unit 52 generates a driving force, the valve needle 54 opens the downstream side communication path 56.

  The valve needle 54 is accommodated in the intermediate chamber 47. The valve needle 54 can be displaced in the intermediate chamber 47 along the axial direction. A valve spring 60 formed in a coil spring shape is inserted into the cylindrical portion 54b of the valve needle 54. One end of the valve spring 60 is in contact with the mounting portion 47 c and the other end is in contact with the disc portion 54 a of the valve needle 54. As a result, the valve spring 60 urges the valve needle 54 toward the driving portion accommodating chamber 48 on the side opposite to the injection hole with respect to the placement portion 47c.

  An upper face portion 54 c is formed on the valve needle 54. The upper face portion 54 c is formed on the upper end surface of the valve needle 54 that faces the downstream communication passage 56. The upper face portion 54c is formed in an annular shape by a spherical inclined surface. The upper face portion 54 c comes into contact with the upper seat portion 47 a by the elastic force of the valve spring 60. Due to the urging force of the valve spring 60 and the fuel pressure difference between the intermediate chamber 47 and the low pressure passage 45, the upper face portion 54c is pressed against the upper seat portion 47a. As the upper face portion 54c is seated on the upper seat portion 47a, the valve needle 54 is closed. At this time, the intermediate passage 59 is in communication with the intermediate chamber 47.

  The valve needle 54 is formed with a lower face portion 54d. The lower face portion 54 d is formed at the tip of the cylindrical portion 54 b of the valve needle 54 that faces the intermediate passage 59. The lower face portion 54d is formed in a flat shape. The lower face portion 54d is pressed against the lower sheet portion 47b by the pressing of the drive pin 71. When the lower face portion 54d is seated on the lower seat portion 47b, the valve needle 54 is closed to block the intermediate passage 59.

  In the valve needle 54, the direction from the pressure control chamber 46 to the drive unit accommodation chamber 48 along the axial direction is the valve closing direction, and the direction from the drive unit accommodation chamber 48 to the pressure control chamber 46 along the axial direction is opened. Direction. When the driving unit 52 does not generate a driving force, the downstream communication passage 56 is closed by the seating of the valve needle 54 on the upper seat 47a. Further, a valve opening gap is formed between the valve needle 54 in the valve closing position and the lower seat portion 47b. The valve opening gap functions as a space that allows displacement of the valve needle 54.

  Next, details of the injection operation of the fuel injection device 100 will be described with reference to FIG. As shown in FIG. 3 (1), application of the drive voltage from the engine control device 17 to the drive unit 52 is interrupted before the start of injection. Therefore, the driving unit 52 does not substantially generate a driving force. Therefore, the valve needle 54 is stationary at the valve closing position where the upper face portion 54c is brought into contact with the upper seat portion 47a. A valve opening gap is formed between the valve needle 54 and the lower seat portion 47b. Since the valve needle 54 is in the closed state, the fuel pressure in the intermediate chamber 47 has risen to substantially the same level as the fuel pressure in the pressure control chamber 46. In the above state, the control plate 53 is pressed against the wall surface around the opening of the inflow channel 43 by the elastic force of the control plate spring 72. The nozzle needle 50 is stationary at the valve closing position where the face portion 63 is in contact with the seat portion 41.

  Next, as shown in FIG. 3 (2), application of the drive voltage from the engine control device 17 to the drive unit 52 is started, and the piezo drive is turned on. As a result, the driving unit 52 generates a driving force. The engine control device 17 controls the drive voltage applied to the drive unit 52 so that a drive force larger than the valve opening force of the valve needle 54 acts on the valve needle 54.

  When the driving unit 52 generates a driving force, the driving pin 71 is displaced. The valve needle 54 pushed down by the drive pin 71 separates the upper face portion 54c from the upper seat portion 47a by displacement in the valve opening direction. In addition, the valve needle 54 brings the lower face portion 54d of the tip of the cylindrical portion 54b into contact with the lower seat portion 47b. Due to the displacement of the valve needle 54 in the valve opening direction, the valve opening gap disappears. Further, the intermediate passage 59 is closed, and the inflow of fuel from the intermediate passage 59 to the intermediate chamber 47 is blocked.

  By opening the valve needle 54 as described above, the pressure control chamber 46 and the low pressure channel 45 are switched from the shut-off state to the communication state. As a result, the high-pressure fuel in the pressure control chamber 46 flows through the first out orifice 53 a of the control plate 53, the upstream communication passage 55, and the intermediate chamber 47 in order, and is discharged to the low pressure passage 45 through the downstream communication passage 56. The

  At this time, the flow area of the downstream communication path 56 is defined by the throttle area of the first out orifice 53a. Therefore, the downstream communication passage 56 is in a throttle state in which the flow rate of fuel flowing from the pressure control chamber 46 to the low pressure passage 45 is limited by the first out orifice 53a.

  The opening area is a flow path area between the upper sheet portion 47a and the upper face portion 54c. In order to enable flow control by the first out orifice 53a, the valve opening gap is defined in advance such that the opening area is larger than the throttle area of the first out orifice 53a.

  Due to the outflow of the fuel through the downstream side communication path 56, the fuel pressure in the pressure control chamber 46 gradually decreases. As a result, the nozzle needle 50 is displaced in the valve opening direction while gradually accelerating toward the pressure control chamber 46 due to the pressure of the high-pressure fuel acting on the face portion 63. The fuel injection from the nozzle hole 44 is started by opening the nozzle needle 50 as described above.

  When the valve needle 54 is brought into the first state by the drive unit 52 in this way, the control plate 53 is in a state where the inflow passage 43 is blocked, and the first out orifice 53a, the upstream communication passage 55, the intermediate chamber 47, and the low pressure passage. The fuel in the pressure control chamber 46 flows out through 45. As a result, the pressure in the pressure control chamber 46 decreases, the nozzle needle 50 is displaced, and the nozzle hole 44 is opened.

  Next, as shown in FIG. 3 (3), 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 52 is interrupted, and the piezo drive is turned off. Then, the driving force of the driving unit 52 falls below the valve opening force of the valve needle 54 and eventually disappears. As described above, the valve needle 54 is displaced toward the valve closing direction by the urging force of the valve spring 60 and the fuel pressure. As a result, the valve is returned to the closed state in which the upper face portion 54c is brought into contact with the upper seat portion 47a. As a result, the pressure control chamber 46 and the low pressure channel 45 are switched from the communication state to the cutoff state, and the downstream side communication passage 56 returns to the closed state.

  On the other hand, the control plate 53 is pushed down by the fuel pressure of the high-pressure fuel flowing from the inflow passage 43. As a result, fuel flows from the inflow passage 43 into the pressure control chamber 46 via the main-in orifice 43a. When the valve needle 54 is displaced in the valve closing direction and is separated from the lower seat portion 47b, the sub-in orifice 59a of the intermediate passage 59 is opened. As a result, the high pressure fuel in the needle storage chamber 58 flows through the intermediate passage 59, the intermediate chamber 47, the upstream communication passage 55, and the pressure control chamber 46 in this order. As a result, the fuel pressures in the intermediate chamber 47 and the pressure control chamber 46 are recovered integrally.

  As a result, as shown in FIG. 3 (4), the nozzle needle 50 is pushed down by the fuel pressure in the pressure control chamber 46 and returns to the state in which the face portion 63 is brought into contact with the seat portion 41 in the valve closing position. . The fuel injection from the nozzle hole 44 is interrupted by the valve closing of the nozzle needle 50 described above. When the fuel pressure in the pressure control chamber 46 is restored, the control plate 53 is in a state of closing the main-in orifice 43a of the inflow channel 43. As a result, the state shown in FIG.

  When the valve needle 54 is brought into the second state by the drive unit 52 in this way, the control plate 53 is in a state where the inflow passage 43 is communicated with the pressure of the inflow passage 43. Accordingly, the fuel flows into the pressure control chamber 46 through the inflow passage 43, the needle accommodating chamber 58, the intermediate passage 59, the intermediate chamber 47, and the upstream communication passage 55, and the pressure in the pressure control chamber 46 rises, and the nozzle The needle 50 is displaced to close the nozzle hole 44.

  Next, the configuration of the intermediate chamber 47 will be described in more detail with reference to FIGS. 4 and 5. A peripheral groove 81 and a communication groove 82 are formed in the lower sheet portion 47 b of the intermediate chamber 47. The peripheral groove 81 is formed between the opening 59 b of the intermediate passage 59 and the opening 55 a of the upstream communication passage 55 so as to surround the opening 59 b of the intermediate passage 59. The peripheral groove 81 is a groove that is recessed from the lower sheet portion 47b. The peripheral groove 81 is formed in an annular shape. The peripheral groove 81 is formed on the inner side than the placement portion 47c.

  The communication groove 82 communicates the peripheral groove 81 and the opening 55a of the upstream communication path 55, and is a groove that is recessed from the lower sheet portion 47b. The communication groove 82 is formed on the shortest path connecting the opening 55 a of the upstream communication path 55 and the peripheral groove 81. Accordingly, the communication groove 82 extends linearly when viewed from the nozzle hole 44 side. Since the peripheral groove 81 surrounds the opening 59 b of the intermediate passage 59, the communication groove 82 is arranged in a path shape connecting the opening 59 b of the intermediate passage 59 and the opening 55 a of the upstream communication passage 55.

  The flow passage areas of the peripheral groove 81 and the communication groove 82, that is, the passage cross-sectional area is larger than the flow passage area of the sub-in orifice 59a. In other words, the flow area of the sub-in orifice 59a is smaller than the flow areas of the peripheral groove 81 and the communication groove 82. As a result, the flow path area when passing through the sub-in orifice 59a is the smallest in the path that flows in sequence to the intermediate passage 59, the intermediate chamber 47, and the upstream communication path 55.

  The diameter D1 of the cylindrical portion 54b of the valve needle 54 is smaller than the outer diameter D2 of the peripheral groove 81. The diameter D1 of the cylindrical portion 54b is larger than the inner diameter D3 of the peripheral groove 81. Accordingly, the outer edge of the cylindrical portion 54 b is located on the side opposite to the injection hole of the peripheral groove 81. As a result, the lower face portion 54d of the cylindrical portion 54b comes into contact with the region between the opening 59b of the intermediate passage 59 and the peripheral groove 81.

  The placement portion 47 c is located on the outer periphery of the peripheral groove 81. In the present embodiment, the lower sheet portion 47b and the placement portion 47c are flush with each other. The inner diameter of the valve spring 60 is larger than the outer diameter D2 of the peripheral groove 81. The wire diameter of the wire constituting the valve spring 60 is preferably larger than the width of the peripheral groove 81. This prevents the valve spring 60 from fitting into the peripheral groove 81.

  Next, the fuel flow through the peripheral groove 81 and the communication groove 82 will be described. As described above, when the injection command to the drive unit 52 is turned off, the valve needle 54 is raised, the lower seat portion 47b is opened, and the upper seat portion 47a is subsequently closed. As a result, the high-pressure fuel from the lower seat portion 47b flows into the pressure control chamber 46 through the upstream communication passage 55, the pressure in the pressure control chamber 46 increases, the nozzle needle 50 is closed, and fuel injection is stopped.

  In the comparative example that does not have the peripheral groove 81 and the communication groove 82 when the fuel flows from the lower seat portion 47b into the pressure control chamber 46, the fuel that has flowed out from the lower seat portion 47b passes through the gap between the lines of the valve spring 60. It flows into the upstream communication path 55. On the other hand, in the present embodiment, the fuel that has flowed out from the lower seat portion 47 b passes through the peripheral groove 81 and the communication groove 82 and flows into the upstream communication path 55. Thereby, high-pressure fuel can be stably flowed into the pressure control chamber 46, and fluctuations in the injection amount can be suppressed.

  As described above, the fuel injection device 100 according to the present embodiment pays attention to the reduction in variation in the fuel flowing into the pressure control chamber 46 in the order of the lower seat portion 47b, the intermediate chamber 47, and the upstream communication passage 55, and the peripheral groove 81 and The communication groove 82 is provided in the lower sheet portion 47b. As a result, the fuel flowing in from the lower seat portion 47 b passes through the peripheral groove 81 and the communication groove 82 formed in the lower seat portion 47 b and flows into the upstream communication passage 55. The peripheral groove 81 and the communication groove 82 are paths that bypass the valve needle 54. The peripheral groove 81 and the communication groove 82 are not affected by the cross-sectional area of the passage depending on the posture of the valve needle 54. Therefore, the fuel that has flowed into the intermediate chamber 47 from the intermediate passage 59 flows into the upstream communication passage 55 through the passage of the peripheral groove 81 and the communication groove 82. Thus, since there is a path that is not affected by the posture of the valve needle 54 and the shape of the valve spring 60, a change in the injection performance can be suppressed. Even if the pressure of the valve needle 54 is affected by the increase in pressure, the peripheral groove 81 and the communication groove 82 can suppress fluctuations in the flow rate. Therefore, in this embodiment, it has tolerance also to the displacement of the valve needle 54 by high pressure.

  Further, by changing the flow of the high-pressure fuel from the gap between the lines of the valve spring 60 to the peripheral groove 81 and the communication groove 82, the high-pressure fuel can be stably flowed into the pressure control chamber 46. Therefore, the injection amount fluctuation can be suppressed even when the pressure is increased.

  In the present embodiment, the communication groove 82 has the shortest path connecting the opening 55 a of the upstream communication path 55 and the peripheral groove 81. Accordingly, the flow resistance from the communication groove 82 to the opening 55a of the upstream communication path 55 can be reduced. Therefore, the fuel that has passed through the peripheral groove 81 can be smoothly flowed to the upstream communication passage 55, and the fluctuation of the flow rate can be further suppressed.

  Further, in the present embodiment, the intermediate passage 59 has a sub-in orifice 59a as a throttle portion having a partially small flow area. The passage cross-sectional area of the sub-in orifice 59a is smaller than the flow passage areas of the communication groove 82 and the peripheral groove 81. The sub-in orifice 59a controls the flow rate of fuel flowing into the intermediate chamber 47 by limiting the flow rate. Accordingly, since the communication groove 82 and the peripheral groove 81 do not serve as flow path resistance in the relationship with the sub-in orifice 59a, the fuel can be smoothly discharged to the upstream communication path 55.

  In the first embodiment, the downstream communication path 56 corresponds to a “discharge path”, and the nozzle needle 50 corresponds to a “valve element”. Further, the valve needle 54 corresponds to a “control member”, the valve spring 60 corresponds to a “control member spring”, and the upstream communication passage 55 corresponds to an “outflow passage”.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is characterized in that the configuration of the communication groove 82 is different. The communication groove 82 includes an outer peripheral groove 82a and a connection groove 82b. The outer peripheral groove 82 a is provided in an annular shape outside the peripheral groove 81. The outer circumferential groove 82 a communicates with the opening 55 a of the upstream communication path 55. A space between the outer peripheral groove 82a and the peripheral groove 81 functions as a mounting portion 47c.

  The connection groove 82b is a plurality of grooves that connect the peripheral groove 81 and the outer peripheral groove 82a. A plurality of connection grooves 82b are formed in the first embodiment shown in FIG. 6, and nine connection grooves 82b are formed in the second embodiment shown in FIG. It extends in the radial direction of the groove 82a. The connection grooves 82b are arranged at equal intervals in the circumferential direction of the outer peripheral groove 82a.

  Further, as shown in FIGS. 6 and 7, the plurality of connection grooves 82 b are imaginary connecting the opening 59 b of the intermediate passage 59 and the opening 55 a of the upstream communication passage 55 when the lower sheet portion 47 b is viewed on the injection hole 44 side. They are arranged symmetrically with respect to a straight line. One connection groove 82b among the plurality of connection grooves 82b connects the shortest path between the peripheral groove 81 and the opening 55a of the upstream communication path 55.

  As described above, in the present embodiment, the communication groove 82 includes the outer peripheral groove 82a and the plurality of connection grooves 82b. Therefore, the fuel that has flowed into the peripheral groove 81 reaches the opening 55a of the upstream communication path 55 via a plurality of paths. . It can be more smoothly guided to the opening 55 a of the upstream communication path 55 than the one communication groove 82.

  In the present embodiment, the plurality of connection grooves 82b are arranged symmetrically with respect to a predetermined virtual straight line. The fuel that has flowed into the intermediate chamber 47 from the opening 59b of the intermediate passage 59 diffuses in various directions. Therefore, the fuel can be guided more smoothly to the outer peripheral groove 82a by arranging the connection grooves 82b in line symmetry.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that there are a plurality of openings 55 a of the upstream communication passage 55. In the present embodiment, a plurality of openings 55a of the upstream communication passage 55 are formed. The opening 55a of the upstream communication passage 55 is disposed so as to sandwich the opening 59b of the intermediate passage 59.

  Two communication grooves 82 are also formed, and are connected to each opening 55a of the upstream communication path 55 through the shortest path. An outer peripheral groove 82 a is formed outside the peripheral groove 81. The outer circumferential groove 82 a communicates with the two openings 55 a of the upstream communication path 55.

  Thus, the upstream communication passage 55 has a plurality of openings 55 a, so that there are a plurality of paths from the intermediate chamber 47 to the pressure control chamber 46, and the fuel flows more smoothly into the pressure control chamber 46. Further, since the two openings 55a of the upstream communication path 55 are positioned so as to sandwich the opening 59b of the intermediate path 59, the flow can flow more smoothly to the opening 55a of the upstream communication path 55 without the path being biased. .

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

  The structure of the above-described embodiment is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention 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 static leakless structure is used, but the present invention is not limited to the static leakless structure. Further, in the first embodiment described above, the valve needle 54 is configured by one member, but is not limited to such a configuration. The valve needle 54 may be configured to connect two members. As a result, when the lift amount of the drive unit 52 is variable, the valve opening speed can be made variable.

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

  DESCRIPTION OF SYMBOLS 15 ... Fuel flow path 16 ... Return flow path 42 ... High pressure flow path 43 ... Inflow flow path 43a ... Main in orifice 44 ... Injection hole 45 ... Low pressure flow path 46 ... Pressure control chamber 47 ... Intermediate | middle chamber 47a ... Upper seat part 47b ... Lower seat part 47c ... Placement part 50 ... Nozzle needle (valve element) 51 ... Valve body 52 ... Drive part 53 ... Control plate 53a ... First out orifice 54 ... Valve needle (control member) 55 ... Upstream communication path (outflow) 55a ... Opening of upstream communication passage 56 ... Downstream communication passage (discharge passage) 58 ... Needle housing chamber (housing chamber) 59 ... Intermediate passage 59a ... Sub-in orifice (throttle portion) 59b ... Opening of intermediate passage 60 ... Valve spring (spring for control member) 81 ... peripheral groove 82 ... communication groove 82a ... outer peripheral groove 82b ... connection groove 100 ... fuel injection device

Claims (6)

A fuel injection device (100) for injecting fuel supplied through a fuel flow path (15) from an injection hole (44) and discharging a part of the supplied fuel to a return flow path (16),
The nozzle hole, a high-pressure channel (42) communicating with the fuel channel, a pressure control chamber (46) into which fuel supplied through the high-pressure channel flows, and a storage into which fuel supplied through the high-pressure channel flows in A chamber (58), an intermediate chamber (47) through which fuel in the pressure control chamber flows out, an outflow passage (55) communicating the pressure control chamber and the intermediate chamber, and an intermediate communicating the storage chamber and the intermediate chamber A valve body (51) forming a passage (59) and a discharge passage (56) for discharging fuel from the intermediate chamber to the return flow path;
A valve body (50) that opens and closes the nozzle hole by being reciprocally displaced by pressure fluctuation in the pressure control chamber,
The pressure is changed between a first state in which the discharge passage is communicated and the intermediate passage is shut off, and a second state in which the discharge passage is shut off and the intermediate passage is communicated. A control member (54) for varying the pressure in the control chamber;
For the control member that is accommodated in the intermediate chamber, one end contacts the lower sheet portion of the intermediate chamber on the injection hole side, the other end contacts the control member, and biases the control member toward the counter injection hole side A spring (60);
A drive unit (52) for displacing the control member to the nozzle hole side or the counter nozzle hole side,
When the control member is brought into the first state by the drive unit, the fuel in the pressure control chamber flows out through at least the outflow passage, the intermediate chamber, and the discharge passage, and the pressure in the pressure control chamber decreases. , The valve body is displaced to open the nozzle hole,
When the control member is brought into the second state by the drive unit, fuel flows into the pressure control chamber via at least the high-pressure flow path, the pressure in the pressure control chamber increases, and the valve body is displaced. And closing the nozzle hole,
The control member is
In the first state, the intermediate passage is blocked by contacting the lower sheet portion (47b) of the intermediate chamber,
In the second state, contacting the upper sheet portion (47a) of the intermediate chamber on the side opposite to the injection hole, blocking the discharge passage,
In the lower sheet part,
A peripheral groove (81) between the opening (59b) of the intermediate passage and the opening (55a) of the outflow passage, and surrounding the opening of the intermediate passage;
A fuel injection device in which a communication groove (82) communicating the peripheral groove and the opening of the outflow passage is formed.   The fuel injection device according to claim 1, wherein the communication groove has a shortest path connecting the opening of the outflow passage and the peripheral groove. The communication groove is
An outer circumferential groove (82a) provided annularly on the outside of the peripheral groove and communicating with the opening of the outflow passage;
The fuel injection device according to claim 1, further comprising a plurality of connection grooves (82 b) communicating the peripheral groove and the outer peripheral groove.   The plurality of connection grooves are arranged in line symmetry with respect to a virtual straight line connecting the opening of the intermediate passage and the opening of the outflow passage when the lower sheet portion is viewed on the nozzle hole side. The fuel injection device described. A plurality of openings of the outflow passage in the intermediate chamber are formed,
The fuel injection device according to any one of claims 1 to 4, wherein the communication groove includes a path that connects the peripheral groove and each opening of the outflow passage. The intermediate passage has a narrowed portion (59a) with a partially small channel area,
The fuel injection device according to any one of claims 1 to 4, wherein a passage cross-sectional area of the throttle portion is smaller than flow passage areas of the communication groove and the peripheral groove.

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