JP2018105212A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of elongating the valve open time without changing a spring.SOLUTION: In a fuel injection device 100, a fuel reservoir chamber 67 is formed by a speed reduction mechanism 80 when a nozzle needle 60 is lifted. The fuel reservoir chamber 67 is formed in a position separated from a communication passage 63 between a pressure receiving part 61 and a partition wall 64 until the nozzle needle 60 reaches an upper limit position from a prescribed lift position after the nozzle needle 60 is displaced to the valve open direction. When the fuel reservoir chamber 67 is formed, fuel in the fuel reservoir chamber 67 is compressed, and force opposing the lifting of the nozzle needle 60 acts on the nozzle needle 60.SELECTED DRAWING: Figure 4

Description

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

  2. Description of the Related Art Conventionally, a fuel injection device is provided with a pressure control chamber type lift mechanism in order to control the lift of a nozzle needle (see, for example, Patent Document 1). Specifically, the fuel injection device includes a nozzle needle that opens and closes the nozzle hole, and the nozzle needle is biased toward the valve closing direction by the fuel pressure in the pressure control chamber. In addition, a high-pressure supply passage for supplying high-pressure fuel to the pressure control chamber and a discharge passage for discharging the fuel in the pressure control chamber to the low-pressure portion are provided, and an intermediate chamber is formed between the pressure control chamber and the discharge passage. . A control valve is disposed in the intermediate chamber. The control valve includes a valve body that opens and closes between the intermediate chamber and the discharge passage, and a spring that biases the valve body in a valve closing direction.

  Then, by opening the control valve and discharging the fuel in the control chamber to the low pressure portion, the nozzle needle is operated in the valve opening direction to start fuel injection. Further, by closing the control valve and allowing high-pressure fuel to flow into the pressure control chamber, the nozzle needle is actuated in the valve closing direction and fuel injection is terminated.

Japanese Patent Laid-Open No. 2003-239821

  In the configuration of the above-described Patent Document 1, the nozzle needle stops at a predetermined position by the biasing force of a spring that biases downward when the nozzle needle is raised. Therefore, it is a structure which does not have a stopper which contacts a nozzle needle and prescribes | regulates a raise position. In the case of a configuration without such a stopper, it is necessary to adjust the rising speed of the nozzle needle by the biasing force of the spring.

  By slowing the rising speed of the nozzle needle, the valve opening time becomes longer, and the injection amount increases. However, there is a problem that the spring is easily affected by changes over time and it is difficult to adjust the urging force.

  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 that can extend the valve opening time without changing the spring.

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

  One aspect of the present invention is a fuel injection device (100) that injects fuel supplied through a fuel flow path (15) from an injection hole (44) and discharges part of the supplied fuel to a return flow path (16). The valve body (40) is located on the valve opening direction side of the valve body (60), and the pressure receiving chamber (61) on which the pressure of the pressure control chamber (53) acts is inserted into the valve pressure chamber. (62) and a partition wall (64) that partitions the valve pressure chamber and the pressure control chamber and is formed with a communication path (63) that communicates the pressure control chamber and the valve pressure chamber. There is a gap between the partition wall and the pressure receiving part at the upper limit position where the valve element is most displaced in the valve opening direction due to the pressure reduction in the control chamber, and the valve element is in the valve opening direction at the partition wall and the pressure receiving part. The communication path between the pressure receiving part and the partition wall is separated from the predetermined lift position until reaching the upper limit position. Deceleration mechanism which forms a fuel reservoir chamber (67) to a position (80) is a fuel injection device is provided.

  According to the present invention, when the driving member switches the control member to the open state in which the outflow passage communicates, the fuel flows out from the fuel outflow chamber to the outflow passage, and the pressure in the fuel outflow chamber decreases. Then, the fuel in the pressure control chamber flows out into the fuel outflow chamber, and the pressure in the pressure control chamber also decreases. Similarly, the fuel in the valve pressure chamber flows out to the pressure control chamber via the communication path, and the pressure in the valve pressure chamber also decreases. As a result, the pressure acting on the pressure receiving portion decreases, so that the valve element is displaced in the valve opening direction against the urging force of the spring and opens.

  When the driving member switches the control member to the closed state in which the outflow passage is blocked, the outflow of fuel from the fuel outflow chamber to the outflow passage stops, and the fuel from the high pressure fuel passage flows into the pressure control chamber. Then, the pressure in the pressure control chamber and the valve pressure chamber rises and the pressure acting on the pressure receiving portion rises, so that the valve body is displaced in the valve closing direction and is closed.

  When the valve body moves up, a fuel reservoir chamber is formed by the speed reduction mechanism. The fuel reservoir chamber is formed at a position away from the communication path between the pressure receiving portion and the partition wall until the valve body is displaced in the valve opening direction and reaches the upper limit position from a predetermined lift position. When the fuel reservoir chamber is formed, the fuel in the fuel reservoir chamber is compressed, and a force opposite to the rising of the valve body acts on the valve body. This reduces the displacement speed of the valve body. When the displacement speed of the valve body is reduced, the valve opening time can be extended as compared with the configuration without the speed reduction mechanism. The deceleration mechanism decelerates using the fuel pressure in the valve pressure chamber. Therefore, it is realizable by selecting the shape of a partition wall and a pressure receiving part, without using another members, such as a new spring. Therefore, the valve opening time can be extended without changing the spring.

  Furthermore, one aspect of the present invention is a fuel injection device that injects fuel supplied through the fuel flow path (15) from the injection hole (44) and discharges part of the supplied fuel to the return flow path (16). 100), and the valve body (40) is positioned on the valve opening direction side of the valve body (60), and the pressure receiving portion (61) on which the pressure of the pressure control chamber (53) acts is inserted. A partition wall (64) in which a communication passage (63) that partitions the chamber (62), the valve pressure chamber and the pressure control chamber, and communicates the pressure control chamber and the valve pressure chamber is formed; There is a gap between the partition wall and the pressure receiving part at the upper limit position where the valve element is most displaced in the valve opening direction due to the pressure reduction in the pressure control chamber, and the valve pressure chamber opens and closes the valve element in the valve opening direction. It has a support surface (56a) for guiding in the valve direction, and the opening on the valve pressure chamber side of the communication path in the partition wall is displaced from the center. A fuel injection system which is formed at a position.

  According to the present invention, when the driving member switches the control member to the open state in which the outflow passage communicates, the fuel flows out from the fuel outflow chamber to the outflow passage, and the pressure in the fuel outflow chamber decreases. Then, the fuel in the pressure control chamber flows out into the fuel outflow chamber, and the pressure in the pressure control chamber also decreases. Similarly, the fuel in the valve pressure chamber flows out to the pressure control chamber via the communication path, and the pressure in the valve pressure chamber also decreases. As a result, the pressure acting on the pressure receiving portion decreases, so that the valve element is displaced in the valve opening direction against the urging force of the spring and opens.

  When the driving member switches the control member to the closed state in which the outflow passage is blocked, the outflow of fuel from the fuel outflow chamber to the outflow passage stops, and the fuel from the high pressure fuel passage flows into the pressure control chamber. Then, the pressure in the pressure control chamber and the valve pressure chamber rises and the pressure acting on the pressure receiving portion rises, so that the valve body is displaced in the valve closing direction and is closed.

  The valve pressure chamber has a support surface that guides the valve body in the valve opening direction and the valve closing direction. The partition wall is formed at a position where the opening on the valve pressure chamber side of the communication path is displaced from the center of the pressure receiving portion. As a result, when the valve body rises, the fuel is difficult to escape from the communication path located at a position shifted from the center, and the fuel tends to temporarily accumulate between the pressure receiving portion and the partition wall. When the fuel is accumulated, the fuel is compressed by the rise of the pressure receiving portion, and a force opposite to the rise of the valve body acts on the valve body. This reduces the displacement speed of the valve body. When the displacement speed of the valve body is reduced, the valve opening time can be extended. Moreover, in this invention, it decelerates using the pressure of the fuel of a valve pressure chamber. Therefore, it is realizable by selecting the position and shape of the communicating path of a partition wall, without using another members, such as a new spring. Therefore, the valve opening time can be extended without changing the spring.

  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 figure which shows a fuel supply system. Sectional drawing which shows a fuel-injection apparatus. The figure explaining operation | movement of a fuel-injection apparatus. The figure explaining the behavior of a pressure receiving part. The figure which shows transition of lift amount. The figure which expands and shows a part of fuel-injection apparatus of 2nd Embodiment. The figure explaining the behavior of a pressure receiving part. The figure which expands and shows a part of fuel injection apparatus of 3rd Embodiment. The figure explaining the behavior of a pressure receiving part.

  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 an electric 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. 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 each fuel injection device 100 via a fuel pipe 14a. In FIG. 1, one fuel injection device 100 is shown, and other illustrations are 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, the fuel pressure acquired from the pressure sensor 14 d 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 at least one injection hole 44, in this embodiment, a 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 pressure control valve 35 that operates based on a drive signal from the engine control device 17, and a main valve portion 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.

  The fuel injection device 100 includes a valve body 40, a nozzle needle 60, an armature 33, a drive unit 30, a return spring 66, and a floating plate 70, as shown in FIG. The valve body 40 is formed with an injection hole 44, a high pressure fuel passage 51a, an inflow passage 52a, an outflow passage 52b, a supply passage 52c, a pressure control chamber 53, an armature chamber 54, a low pressure fuel passage 51b, and a valve pressure chamber 62. .

  As shown in FIG. 2, the injection hole 44 is formed at the distal end in the insertion direction in the valve body 40 inserted into the combustion chamber 22. The tip is formed in a conical or hemispherical shape. A plurality of nozzle holes 44 are provided radially from the inside to the outside of the valve body 40. High-pressure fuel is injected into the combustion chamber 22 through the injection hole 44. By passing through the nozzle hole 44, the fuel is vaporized and easily mixed with air.

  The high-pressure fuel passage 51 a is connected to the fuel passage 15. The high-pressure fuel passage 51a distributes the high-pressure fuel supplied from the common rail 14 to the inflow passage 52a and the supply passage 52c. The inflow passage 52a allows the high pressure fuel passage 51a and the pressure control chamber 53 to communicate with each other. The inflow passage 52 a allows high-pressure fuel to flow into the pressure control chamber 53. The outflow passage 52b allows the pressure control chamber 53 and the armature chamber 54 to communicate with each other. The outflow passage 52 b allows the fuel in the pressure control chamber 53 to flow out to the armature chamber 54. The supply passage 52 c allows high-pressure fuel supplied through the high-pressure fuel passage 51 a to flow to the injection hole 44.

  The pressure control chamber 53 is provided inside the valve body 40 on the opposite side of the nozzle hole 44 with the nozzle needle 60 interposed therebetween. High-pressure fuel supplied through the fuel flow path 15 and the inflow passage 52a flows into the pressure control chamber 53. The pressure of the fuel in the pressure control chamber 53 varies depending on the inflow of high-pressure fuel from the inflow passage 52a and the outflow of fuel to the armature chamber 54 through the outflow passage 52b. The pressure control chamber 53 reciprocates the nozzle needle 60 by utilizing fuel pressure fluctuation.

  Fuel flows out from the pressure control chamber 53 into the armature chamber 54 through the outflow passage 52b. The armature chamber 54 accommodates the armature 33 so as to be capable of reciprocating displacement. The fuel pressure in the armature chamber 54 is lower than the fuel pressure in the pressure control chamber 53.

  The low pressure fuel passage 51b is connected to the armature chamber 54 and the return pipe 14c. The low pressure fuel passage 51 b extends along the high pressure fuel passage 51 a in the valve body 40. The low pressure fuel passage 51b discharges the fuel in the armature chamber 54 to the return pipe 14c.

  The valve body 40 includes a nozzle body 41, a cylinder 56, an orifice plate 46, a holder 48, and the like formed of a metal material. The nozzle body 41, the orifice plate 46, and the holder 48 are arranged in this order from the distal end side in the insertion direction of the fuel injection device 100.

  The nozzle body 41 is a bottomed cylindrical member. The nozzle body 41 has a nozzle hole 44 and a supply passage 52c. The nozzle body 41 has a nozzle needle housing chamber 43 and a seat portion 45. The nozzle needle storage chamber 43 is formed in a cylindrical hole shape, and stores the nozzle needle 60 and the cylinder 56. The nozzle needle storage chamber 43 defines a supply passage 52 c together with the cylinder 56. The seat portion 45 is formed in a conical shape inside the tip portion and faces the supply passage 52c.

  The cylinder 56 is formed in a cylindrical shape. The cylinder 56 defines the pressure control chamber 53 together with the orifice plate 46. The cylinder 56 has a partition wall 64 that partitions the pressure control chamber 53 side and the valve pressure chamber 62 side inside. The partition wall 64 is formed with a communication passage 63 that allows the pressure control chamber 53 and the valve pressure chamber 62 to communicate with each other. The cylinder 56 is disposed on the inner peripheral side of the nozzle body 41 so as to be coaxial with the nozzle body 41. Since the pressure control chamber 53 and the valve pressure chamber 62 communicate with each other through the communication path 63, the pressures in the pressure control chamber 53 and the valve pressure chamber 62 change in the same manner.

  The orifice plate 46 is formed in a disc shape. In the orifice plate 46, an inflow passage 52a and an outflow passage 52b are formed. The orifice plate 46 has a control sheet portion 46a. The control sheet portion 46a is formed so as to surround the opening of the outflow passage 52b in the top surface of the orifice plate 46 facing the holder 48 side. The control seat portion 46 a forms a pressure control valve 35 together with the armature 33.

  The holder 48 is formed in a cylindrical shape. The holder 48 is formed with two vertical holes extending along the axial direction. Each vertical hole forms a high-pressure fuel passage 51a and a low-pressure fuel passage 51b, respectively. The holder 48 is formed with an armature chamber 54 for accommodating the armature 33 therein. The holder 48 accommodates the drive unit 30.

  The nozzle needle 60 is formed in a cylindrical shape as a whole by a metal material. The nozzle needle 60 is accommodated in the nozzle body 41. A pressure receiving portion 61, which is one end of the nozzle needle 60, is inserted into the cylinder 56. The nozzle needle 60 is guided by a support surface 56a formed on the inner wall of the cylinder 56, and can be reciprocally displaced along the support surface 56a in the valve opening direction and the valve closing direction which are axial directions.

  The nozzle needle 60 has a pressure receiving portion 61 at an end portion on the valve opening direction side and a face portion 65 at an end portion on the valve closing direction side. The nozzle needle 60 is reciprocally displaced along the axial direction of the nozzle body 41 due to the fluctuation of the fuel pressure in the pressure control chamber 53 received by the pressure receiving portion 61, and the face portion 65 is seated on the seat portion 45. The face portion 65 forms a main valve portion 50 that opens and closes the nozzle hole 44 together with the seat portion 45. When the face portion 65 is separated from the seat portion 45, the injection hole 44 is opened and fuel is injected. When the face portion 65 is seated on the seat portion 45, the injection hole 44 is closed and fuel injection is stopped.

  The armature 33 is accommodated in the armature chamber 54 and can be reciprocally displaced in the armature chamber 54. The armature 33 is a two-stage cylindrical member formed of a metal material that is a ferromagnetic material. The armature 33 varies the pressure in the pressure control chamber 53 by controlling the outflow of fuel from the pressure control chamber 53 to the armature chamber 54. The armature 33 has a suction part 33a and a control face part 33b. The suction part 33a is formed in a circular plate shape. The suction unit 33 a is sucked toward the drive unit 30 by the magnetic force generated by the drive unit 30. The control face portion 33b is formed at the tip of a cylindrical portion that protrudes from the center of the suction portion 33a toward the opening of the outflow passage 52b. The control face portion 33 b is pressed against the control sheet portion 46 a by the displacement of the armature 33, and can close the opening of the outflow passage 52 b that faces the armature chamber 54.

  The drive unit 30 is an electromagnetic actuator, and drives the armature 33 with a magnetic force. The drive unit 30 is disposed above the armature 33. The drive unit 30 includes a solenoid 31a and a spring 31c. A pulsed drive signal is supplied from the engine control device 17 to the solenoid 31a. The solenoid 31a generates a magnetic field by supplying a drive signal, and attracts the suction portion 33a with a magnetic force. The spring 31c is a coil spring in which a metal wire is wound spirally. The spring 31 c biases the armature 33 in a direction in which the armature 33 is separated from the lower surface of the driving unit 30.

  When the power supply from the engine control device 17 is not supplied, the above drive unit 30 seats the control face portion 33b on the control seat portion 46a by the urging force of the spring 31c. As a result, the pressure control valve 35 is in a closed state in which communication between the pressure control chamber 53 and the armature chamber 54 that is the fuel outflow chamber is blocked.

  On the other hand, when power is supplied from the engine control device 17, the drive unit 30 sucks the armature 33 and separates the control face unit 33b from the control seat unit 46a. As a result, the pressure control valve 35 is in an open state in which the pressure control chamber 53 and the armature chamber 54 are communicated. As described above, the drive unit 30 opens and closes the pressure control valve 35 by reciprocating the armature 33 under the control of the engine control device 17. As a result, the outflow of fuel from the pressure control chamber 53 to the armature chamber 54 is controlled by the pressure control valve 35.

  The floating plate 70 is accommodated in the pressure control chamber 53, and switches between a state in which the high pressure fuel passage 51a communicates and a state in which the high pressure fuel passage 51a is blocked. Further, the floating plate 70 is formed with an out orifice 71 which is an insertion hole for communicating the outflow passage 52b and the pressure control chamber 53. The floating plate 70 is formed in a disk shape from a metal material. The floating plate 70 is disposed in the pressure control chamber 53 so as to be reciprocally displaced along the axial direction of the nozzle body 41. The floating plate 70 is biased toward the orifice plate 46 by a plate spring 72. An out orifice 71 is formed in the floating plate 70. The out orifice 71 is a through hole that penetrates the floating plate 70 in the thickness direction. The channel area of the out orifice 71 is defined to be narrower than the channel area of the outflow passage 52b. The out-orifice 71 allows the fuel to flow out from the pressure control chamber 53 to the outflow passage 52b and restricts the flow rate of the fuel outflowing into the outflow passage 52b when the floating plate 70 is in close contact with the orifice plate 46.

  In the fuel injection device 100 described above, by opening the pressure control valve 35, the fuel in the pressure control chamber 53 flows out to the armature chamber 54 through the out orifice 71 and the outflow passage 52b. As a result, the fuel pressure in the pressure control chamber 53 decreases, and similarly, the fuel pressure in the valve pressure chamber 62 decreases, and the nozzle needle 60 moves to the pressure control chamber 53 side to open the nozzle hole 44. When the communication between the pressure control chamber 53 and the armature chamber 54 is cut off by closing the pressure control valve 35, the fuel supplied through the inflow passage 52a resists the urging force of the plate spring 72. The pressure flows into the pressure control chamber 53 while being pushed down. As a result, the fuel pressure in the pressure control chamber 53 and the valve pressure chamber 62 is restored, and the nozzle needle 60 moves toward the seat portion 45 to close the nozzle hole 44.

  Next, the operation in which the fuel injection device 100 performs fuel injection according to the drive current from the engine control device 17 will be described with reference to FIG. Before the injection, that is, when the injection is stopped, the drive current does not flow through the solenoid 31a. Therefore, since the armature 33 is in a valve-closed state, the fuel pressure in the pressure control chamber 53 and the valve pressure chamber 62 is maintained at a high level. Therefore, the nozzle needle 60 is pushed down by the fuel pressure in the valve pressure chamber 62, and the closed state of the nozzle hole 44 is maintained. The floating plate 70 is in a state where the high-pressure fuel passage 51a is blocked.

  Next, the operation at the start of injection will be described. In order to inject fuel, when the valve opening control is performed so that the drive current from the engine control device 17 is supplied to the solenoid 31 a and the pressure control valve 35 is started to open, the outflow passage 52 b is in communication with the armature chamber 54. Then, the fuel in the pressure control chamber 53 flows out to the armature chamber 54 through the out orifice 71 and the outflow passage 52b. As a result, the fuel pressure in the pressure control chamber 53 decreases, similarly the fuel pressure in the valve pressure chamber 62 decreases, and the nozzle needle 60 moves to the pressure control chamber 53 side to open the nozzle hole 44. . This starts the injection. In this state, the floating plate 70 maintains the state where the high-pressure fuel passage 51 a is blocked by the pressure in the pressure control chamber 53. There is a gap between the pressure receiving portion 61 and the cylinder 56 at the upper limit position where the nozzle hole 44 is opened and the nozzle needle 60 is displaced to the most valve opening direction side. Therefore, the upper limit position of the nozzle needle 60 is regulated by the urging force of the return spring 66. In other words, it is a flying needle system that does not have a restricting portion that restricts the upper limit position of the nozzle needle 60.

  Next, the operation at the end of injection will be described. When the drive current is stopped by the engine control device 17 to stop the injection, the pressure control valve 35 is closed by the spring 31c, and the outflow passage 52b is cut off from the armature chamber 54. Then, the fuel supplied through the inflow passage 52 a flows into the pressure control chamber 53 while pushing down the floating plate 70. Therefore, the floating plate 70 is in a state of communicating with the high-pressure fuel passage 51a.

  As a result, the fuel pressure in the pressure control chamber 53 and the valve pressure chamber 62 is restored, so that the nozzle needle 60 is pushed down toward the seat portion 45 to close the nozzle hole 44. Further, when the fuel pressure in the pressure control chamber 53 is recovered, the floating plate 70 is displaced toward the orifice plate 46 by the urging force of the plate spring 72, and the high-pressure fuel passage 51a is shut off.

  Next, the configuration of the valve pressure chamber 62 and the behavior of the nozzle needle 60 will be described in more detail with reference to FIGS. 4 and 5. As shown in FIGS. 2 and 4, the partition wall 64 is formed with a communication path 63 that partitions the valve pressure chamber 62 and the pressure control chamber 53 and communicates the pressure control chamber 53 and the valve pressure chamber 62. . The valve pressure chamber 62 is a space surrounded by the inner wall of the cylinder 56, the partition wall 64, and the pressure receiving portion 61 of the nozzle needle 60.

  The partition wall 64 and the pressure receiving portion 61 have a speed reduction mechanism 80 that reduces the displacement speed of the nozzle needle 60 in the valve opening direction (upward in FIG. 2) by the fuel pressure in the valve pressure chamber 62. The partition wall 64 and the pressure receiving portion 61 include a communication path 63 between the pressure receiving portion 61 and the partition wall 64 until the nozzle needle 60 is displaced in the valve opening direction and reaches the upper limit position from a predetermined lift position. Forms a fuel reservoir 67 at a remote location. In this embodiment, the fuel reservoir 67 has a convex portion 81 in one pressure receiving portion 61 and a concave portion 82 in the other partition wall 64 of the pressure receiving portion 61 and the partition wall 64. This is realized by the convex part 81 having and the concave part 82 having the partition wall 64.

  The recess 82 is formed on the partition wall 64 on the valve pressure chamber 62 side. The recess 82 is recessed toward the pressure control chamber 53, has an annular shape, and is continuously formed so as to surround the outer periphery of the communication path 63. The concave portion 82 engages with the convex portion 81 of the pressure receiving portion 61 when the nozzle needle 60 is displaced in the valve opening direction.

  In a state where the convex portion 81 is engaged with the concave portion 82, a space surrounded by the convex portion 81 and the concave portion 82 becomes the fuel reservoir chamber 67. As shown at the start of injection in FIG. 3, the fuel reservoir 67 is located away from the communication path 63. Specifically, a communication space that communicates with the communication path 63 is formed by the partition wall 64 and the pressure receiving portion 61. The communication space communicates with the fuel reservoir chamber 67 through the clearance between the concave portion 82 and the convex portion 81.

  The volume of the fuel reservoir 67 varies depending on the lift position of the nozzle needle 60, and the largest portion of the convex portion 81 starts to engage with the concave portion 82. The volume of the fuel reservoir 67 is the smallest when it is disposed at the lift limit position of the nozzle needle 60. Even when the volume of the fuel reservoir 67 is the largest, it is smaller than the volume of the communication space.

  Next, the behavior of the nozzle needle 60 will be described in the order of (1) to (5) in FIGS. (1) The armature 33 is sucked by the drive unit 30, the fuel in the pressure control chamber 53 is discharged to the armature chamber 54 through the out orifice 71, and the nozzle needle 60 is raised.

  (2) The nozzle needle 60 is raised, and the convex portion 81 of the pressure receiving portion 61 enters the concave portion 82 of the partition wall 64, and a fuel reservoir chamber 67 defined by the concave portion 82 and the convex portion 81 is formed. The shape of the convex portion 81 and the concave portion 82 is selected so that the tip area of the convex portion 81 is larger than the sliding clearance area. The sliding clearance area is the total area of the gap between the concave portion 82 and the convex portion 81. As the nozzle needle 60 rises, the volume of the fuel reservoir 67 decreases and the fuel pressure in the fuel reservoir 67 increases. A force that pushes down the convex portion 81 is generated by the increased fuel pressure, and the rising speed of the nozzle needle 60 gradually decreases as shown in FIG.

  (3) The nozzle needle 60 gradually rises and stops when the nozzle needle 60 reaches the lift limit. Even at the lift limit position, the tip of the convex portion 81 is not in contact with the bottom of the concave portion 82 and is separated. Therefore, the lift limit position is defined by the return spring 66. Then, the drive unit 30 is controlled so that the armature 33 is closed.

  (4) When the armature 33 is closed, the pressure in the inflow passage 52a is higher than the pressure in the pressure control chamber 53, so that the floating plate 70 is pushed down by the fuel pressure in the inflow passage 52a. Therefore, the fuel supplied through the inflow passage 52 a flows into the pressure control chamber 53 while pushing down the floating plate 70. As a result, the floating plate 70 communicates with the high-pressure fuel passage 51a. At this time, the fuel reservoir 67 is formed. The amount of inflow in the fuel reservoir 67 is limited by the sliding clearance, and the pressure does not easily rise, and a pressing force due to the fuel pressure acts on the pressure receiving portion 61 that forms the communication space, but the convex portion 81 does not act as a pressing force. Therefore, the nozzle needle 60 is slowly lowered as compared with the case where the pressing force acts on the entire pressure receiving portion 61.

  (5) When the nozzle needle 60 is lowered to a predetermined position, the convex portion 81 and the concave portion 82 are separated, and the fuel reservoir 67 disappears. Then, a pressing force due to the fuel pressure acts on the entire pressure receiving portion 61. As a result, the lowering speed of the nozzle needle 60 is increased, and the nozzle needle 60 is lowered to the valve closing position.

  FIG. 5 shows the relationship between the lift amount and time by comparing the example and the comparative example. (1) to (5) shown in FIG. 5 correspond to (1) to (5) in FIG. The comparative example has a configuration without the concave portion 82 and the convex portion 81, the pressure receiving portion 61 is flat, and the partition wall 64 is also flat.

  In the comparative example, since the fuel reservoir chamber 67 is not formed, the nozzle needle rises at a constant speed and descends at a constant speed. On the other hand, in the embodiment, as described above, (2) the fuel reservoir chamber 67 is formed to lower the ascending speed, and (4) the fuel reservoir chamber 67 is formed to lower the descending speed. . As a result, the injection period becomes longer than that of the comparative example, and the injection amount also increases.

  As described above, in the fuel injection device 100 of the present embodiment, the fuel reservoir chamber 67 is formed by the speed reduction mechanism 80 when the nozzle needle 60 is raised. The fuel reservoir 67 is located away from the communication path 63 between the pressure receiving portion 61 and the partition wall 64 until the nozzle needle 60 is displaced in the valve opening direction and reaches the upper limit position from the predetermined lift position. Formed. When the fuel reservoir 67 is formed, the fuel in the fuel reservoir 67 is compressed, and a force opposite to the rise of the nozzle needle 60 acts on the nozzle needle 60. This reduces the displacement speed of the nozzle needle 60. When the displacement speed of the nozzle needle 60 is reduced, the valve opening time can be extended as compared with the configuration without the speed reduction mechanism 80. The deceleration mechanism 80 decelerates using the fuel pressure in the valve pressure chamber 62. Therefore, it is realizable by selecting the shape of the partition wall 64 and the pressure receiving part 61, without using another members, such as a new spring. Therefore, the valve opening time can be extended without changing the return spring 66.

  In this embodiment, the speed reduction mechanism 80 is formed on the convex portion 81 formed on the pressure receiving portion 61 and the partition wall 64, and engages with the convex portion 81 when the nozzle needle 60 is displaced in the valve opening direction. And a recess 82. The speed reduction mechanism 80 can be realized with such a simple configuration of the concave portion 82 and the convex portion 81.

  Further, in the present embodiment, the floating plate 70 closes the pressure control chamber 53 when the nozzle needle 60 is closed, and opens when the pressure in the pressure control chamber 53 decreases, and high-pressure fuel flows in. To do. Therefore, the fuel injection device 100 of this embodiment has a static leakless structure in which fuel is not always supplied to the pressure control chamber 53. Therefore, since the fuel is not supplied to the pressure control chamber 53 while the nozzle needle 60 is raised, the time until the lift limit position is reached can be lengthened.

  Furthermore, the fuel injection device 100 of the present embodiment has a flying needle structure that does not have a stopper that restricts the lift limit position of the nozzle needle 60. Thereby, since the nozzle needle 60 does not contact the stopper or the like at the lift limit position, damage due to contact can be suppressed.

  In the first embodiment, the armature 33 corresponds to a “control member”, the low-pressure fuel passage 51 b corresponds to a “discharge passage”, and the armature chamber 54 corresponds to a “fuel outflow chamber”. The nozzle needle 60 corresponds to a “valve element”, and the floating plate 70 corresponds to a “movable plate”.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that a concave portion 82 is formed in the pressure receiving portion 61 and a convex portion 81 is formed in the partition wall 64.

  The convex portion 81 is formed on the valve pressure chamber 62 side of the partition wall 64. The convex portion 81 is formed integrally with the inner wall of the cylinder 56. Therefore, the convex portion 81 can also be referred to as a step provided on the inner wall of the cylinder 56, the partition wall 64, and the coupling portion. The recess 82 is formed at the peripheral edge of the pressure receiving portion 61. The convex portion 81 engages with the concave portion 82 of the pressure receiving portion 61 when the nozzle needle 60 is displaced in the valve opening direction. As shown in FIG. 6, the space surrounded by the convex portion 81 and the concave portion 82 becomes the fuel reservoir 67 with the convex portion 81 engaged with the concave portion 82. The fuel sump chamber 67 is located away from the communication path 63.

  Next, the behavior of the nozzle needle 60 will be described in the order of FIGS. 7 (1) to (5). (1) The armature 33 is sucked by the drive unit 30, the fuel in the pressure control chamber 53 is discharged to the armature chamber 54 through the out orifice 71, and the nozzle needle 60 is raised.

  (2) The nozzle needle 60 is raised, and the concave portion 82 of the pressure receiving portion 61 is engaged with the convex portion 81 of the partition wall 64, so that the fuel reservoir chamber 67 defined by the concave portion 82 and the convex portion 81 is formed. As the nozzle needle 60 rises, the volume of the fuel reservoir 67 decreases and the fuel pressure in the fuel reservoir 67 increases. A force that pushes down the recess 82 is generated by the increased fuel pressure, and the rising speed of the nozzle needle 60 gradually decreases.

  (3) The nozzle needle 60 gradually rises and stops when the nozzle needle 60 reaches the lift limit. Even at the lift limit position, the bottom of the concave portion 82 is not in contact with the tip of the convex portion 81 and is separated. Therefore, the lift limit position is defined by the return spring 66. Then, the drive unit 30 is controlled so that the armature 33 is closed.

  (4) When the armature 33 is closed, the floating plate 70 is pushed down as described above, and fuel flows into the pressure control chamber 53 through the inflow passage 52a. At this time, the fuel reservoir 67 is formed. The amount of inflow in the fuel reservoir 67 is limited by the sliding clearance, and the pressure does not easily rise, and a pressing force due to the fuel pressure acts on the pressure receiving portion 61 that forms the communication space, but the recess 82 does not act as a pressing force. Therefore, the nozzle needle 60 is slowly lowered as compared with the case where the pressing force acts on the entire pressure receiving portion 61.

  (5) When the nozzle needle 60 is lowered to a predetermined position, the convex portion 81 and the concave portion 82 are separated, and the fuel reservoir 67 disappears. Then, a pressing force due to the fuel pressure acts on the entire pressure receiving portion 61. As a result, the lowering speed of the nozzle needle 60 is increased, and the nozzle needle 60 is lowered to the valve closing position.

  Thus, in this embodiment, although the recessed part 82 is formed in the pressure receiving part 61 and the convex part 81 is formed in the partition wall 64, there can exist the same effect | action and effect of 1st Embodiment.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the pressure receiving portion 61 and the partition wall 64 are both flat and have a feature in the position of the communication path 63.

  The partition wall 64 is formed at a position where a lower opening 62 a that is an opening on the valve pressure chamber 62 side of the communication path 63 is shifted from the center of the pressure receiving portion 61. The lower opening 62 a is located at a position shifted outward from the center of the partition wall 64. An upper opening 62 b that is an opening on the pressure control chamber 53 side of the communication path 63 is opened so as to include the center of the pressure receiving portion 61. Therefore, the communication path 63 extends in a direction inclined with respect to the vertical direction. In addition, there is a gap between the partition wall 64 and the pressure receiving portion 61 at the upper limit position, which is the lift limit position where the nozzle needle 60 is most displaced in the valve opening direction due to the pressure reduction in the pressure control chamber 53.

  Next, the behavior of the nozzle needle 60 will be described in the order of FIGS. 9 (1) to (5). (1) The armature 33 is sucked by the drive unit 30, the fuel in the pressure control chamber 53 is discharged to the armature chamber 54 through the out orifice 71, and the nozzle needle 60 is raised.

  (2) Since the communication path 63 is in an offset position, it is difficult for fuel to escape from the valve pressure chamber 62 to the pressure control chamber 53 as compared with the case where the communication path 63 is at the center. Therefore, at a position opposite to the position where the communication path 63 is displaced, fuel stays and the fuel pressure rises, generating a force to push down the pressure receiving portion 61, and the rising speed of the nozzle needle 60 gradually decreases.

  (3) The nozzle needle 60 gradually rises and stops when the nozzle needle 60 reaches the lift limit. Even at the lift limit position, the pressure receiving portion 61 and the partition wall 64 are not in contact with each other and are separated. Then, the drive unit 30 is controlled so that the armature 33 is closed.

  (4) When the armature 33 is closed, the floating plate 70 is pushed down as described above, and fuel flows into the pressure control chamber 53 through the inflow passage 52a. The fuel also flows into the valve pressure chamber 62 via the communication path 63, but the fuel does not easily flow because the communication path 63 is in a shifted position. Accordingly, the pressing force is weakened, and the nozzle needle 60 is slowly lowered.

  (5) When the nozzle needle 60 is lowered to a predetermined position, the interval between the partition wall 64 and the pressure receiving portion 61 is widened, so that the fuel can flow more easily than when the nozzle needle 60 is lowered. Accordingly, the lowering speed of the nozzle needle 60 is increased and is lowered to the valve closing position.

  Thus, in the present embodiment, the lower opening 62a of the communication path 63 is at a position shifted from the center. This makes it difficult for fuel to escape from the valve pressure chamber 62 and also makes it difficult for the fuel to enter the valve pressure chamber 62, so that the injection period can be extended. Therefore, the injection amount can be increased. With the simple configuration of shifting the position of the lower opening 62a of the communication path 63, the same effects as in the first embodiment can be achieved.

(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 fuel reservoir 67 is formed by the concave portion 82 and the convex portion 81 having a rectangular cross section in the axial direction of the nozzle needle 60, but is not limited to the rectangular shape. For example, the convex part 81 and the recessed part 82 with a circular arc cross section may be sufficient, and the triangular recessed part 82 and the convex part 81 which have an inclined surface in a cross section may be sufficient.

  In the first embodiment described above, the static leakless structure is used, but the present invention is not limited to the static leakless structure. A configuration in which high-pressure fuel is always supplied to the pressure control chamber 53 may be employed.

DESCRIPTION OF SYMBOLS 10 ... Fuel supply system 15 ... Fuel flow path 16 ... Return flow path 30 ... Drive part 33 ... Armature (control member) 40 ... Valve body 44 ... Injection hole 51a ... High-pressure fuel passage 51b ... Low-pressure fuel passage (discharge passage) 52a ... Inflow passage 52b ... Outflow passage 53 ... Pressure control chamber 54 ... Armature chamber (fuel outflow chamber) 56a ... Support surface 60 ... Nozzle needle (valve element) 61 ... Pressure receiving portion 62 ... Valve pressure chamber 63 ... Communication passage 64 ... Partition wall 66 ... Return spring (spring) 67 ... Fuel reservoir 70 ... Floating plate (movable plate) 71 ... Out orifice (insertion hole)
DESCRIPTION OF SYMBOLS 80 ... Deceleration mechanism 81 ... Convex part 82 ... Concave part 100 ... Fuel-injection apparatus

Claims (4)

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 fuel passage (51a) communicating with the fuel flow path, a pressure control chamber (53) into which fuel supplied through the high-pressure fuel passage flows, and a fuel outflow chamber (from which fuel in the pressure control chamber flows out) 54), a valve forming an outflow passage (52b) for flowing fuel from the pressure control chamber to the fuel outflow chamber, and a discharge passage (51b) for discharging fuel from the fuel outflow chamber to the return flow path. Body (40),
A valve body (60) which is accommodated in the valve body and opens and closes the nozzle hole by reciprocating displacement due to pressure fluctuations in the pressure control chamber;
A control member (33) that is accommodated in the fuel outflow chamber and switches between an open state in which the outflow passage is communicated and a closed state in which the outflow passage is shut off to vary the pressure in the pressure control chamber;
A drive unit (30) for switching between a closed state and an open state of the control member;
A spring (66) housed in the valve body and biasing the valve body in a valve closing direction,
The valve body is
A valve pressure chamber (62) which is located on the valve opening direction side of the valve body and into which a pressure receiving portion (61) on which the pressure of the pressure control chamber acts is inserted;
A partition wall (64) in which the valve pressure chamber and the pressure control chamber are partitioned, and a communication passage (63) that communicates the pressure control chamber and the valve pressure chamber is formed;
At the upper limit position where the valve element is most displaced in the valve opening direction side due to the pressure decrease in the pressure control chamber, there is a gap between the partition wall and the pressure receiving portion,
The partition wall and the pressure receiving portion include the communication path between the pressure receiving portion and the partition wall until the valve body is displaced in a valve opening direction and reaches a maximum lift position from a predetermined lift position. A fuel injection device provided with a speed reduction mechanism (80) for forming a fuel reservoir (67) at a distant position. The valve pressure chamber has a support surface (56a) for guiding the valve body in the valve opening direction and the valve closing direction,
The deceleration mechanism is
A convex portion (81) formed on one of the pressure receiving portion and the partition wall;
2. The concave portion (82) formed on one of the pressure receiving portion and the partition wall and engaged with the convex portion when the valve body is displaced in the valve opening direction. Fuel injectors. A fuel injection device 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 fuel passage (51a) communicating with the fuel flow path, a pressure control chamber (53) into which fuel supplied through the high-pressure fuel passage flows, and a fuel outflow chamber (from which fuel in the pressure control chamber flows out) 54), a valve forming an outflow passage (52b) for flowing fuel from the pressure control chamber to the fuel outflow chamber, and a discharge passage (51b) for discharging fuel from the fuel outflow chamber to the return flow path. Body (40),
A valve body (60) which is accommodated in the valve body and opens and closes the nozzle hole by reciprocating displacement due to pressure fluctuations in the pressure control chamber;
A control member (33) that is accommodated in the fuel outflow chamber and switches between an open state in which the outflow passage is communicated and a closed state in which the outflow passage is shut off to vary the pressure in the pressure control chamber;
A drive unit (30) for switching between a closed state and an open state of the control member;
A spring (66) housed in the valve body and biasing the valve body in a valve closing direction,
The valve body is
A valve pressure chamber (62) which is located on the valve opening direction side of the valve body and into which a pressure receiving portion (61) on which the pressure of the pressure control chamber acts is inserted;
A partition wall (64) in which the valve pressure chamber and the pressure control chamber are partitioned, and a communication passage (63) that communicates the pressure control chamber and the valve pressure chamber is formed;
At the upper limit position where the valve element is most displaced in the valve opening direction side due to the pressure decrease in the pressure control chamber, there is a gap between the partition wall and the pressure receiving portion,
The valve pressure chamber has a support surface (56a) for guiding the valve body in the valve opening direction and the valve closing direction,
The fuel injection device, wherein an opening on the valve pressure chamber side of the communication path in the partition wall is formed at a position shifted from the center of the pressure receiving portion. A movable housing that is housed in the pressure control chamber and switches between a state in which the high-pressure fuel passage is in communication and a state in which the high-pressure fuel passage is cut off, and has an insertion hole (71) that connects the outflow passage and the pressure control chamber. A plate (70),
When the control member causes the control member to communicate with the outflow passage, the movable plate shuts off the high-pressure fuel passage, and the fuel in the pressure control chamber passes through the insertion hole and the outflow passage. Outflowing from the outflow passage, the pressure in the pressure control chamber is lowered, the valve body is displaced in the valve opening direction to open the nozzle hole,
When the control member causes the control member to block the outflow passage, the movable plate is brought into communication with the high-pressure fuel passage by the pressure of the high-pressure fuel passage, and the pressure control chamber passes through the high-pressure fuel passage. The fuel flows into the gas, the pressure in the pressure control chamber increases, and the valve body is displaced in the valve closing direction to close the nozzle hole. Fuel injectors.

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