JP5494453B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device including a pressure-responsive control member for adjusting a fuel pressure acting on a valve member that intermittently injects fuel from an injection hole.

  In Patent Document 1, Patent Document 2, and Patent Document 3, a pressure chamber that applies fuel pressure to a valve member that intermittently injects fuel from an injection hole, and a valve member is moved by adjusting the pressure in the pressure chamber. A fuel injection device including a pressure adjustment mechanism is disclosed. In these fuel injection devices, it has been proposed that the pressure adjusting mechanism uses a pressure responsive control member that moves in response to a pressure change caused by opening and closing of an electromagnetic valve. Such a control member receives fluid resistance at the contact surface with other members.

European Patent No. 1656498 JP-A-6-108948 Japanese Patent No. 4054621

  In the configuration of the prior art, if the area of the contact surface between the control member and the other member is large, the fluid resistance increases and the responsiveness may decrease. Further, the viscosity of the fuel changes depending on the temperature. For this reason, the fluid resistance resulting from the contact surface changes according to the temperature. As a result, when the area of the contact surface is large, the fluid resistance force fluctuates greatly, and there is a possibility that the jetting characteristics fluctuate.

  FIG. 7 is a partially enlarged cross-sectional view of a fuel injection device P10 of a comparative example. The fuel injection device P10 includes an orifice member P1 as a housing member, a cylinder P2, a nozzle needle P3, and a floating plate P5 as a control member. A pressure chamber P4 is formed between the orifice member P1, the cylinder P2, and the nozzle needle P3. The orifice member P1 has a main supply path P11 for supplying high pressure fuel. The high pressure fuel is supplied from the main supply path P11 to the nozzle hole through the outside of the cylinder P2 and the outside of the nozzle needle P3. The orifice member P1 has an annular recess P13 that partitions the high-pressure chamber and a circular recess P14 that partitions the control pressure chamber on the contact surface P12 facing the floating plate P5. High-pressure fuel is introduced into the recess P13 via the passage P15. The recess P14 communicates with the control valve via the passage P16. The fuel in the recess P14 is discharged via the passage P16 only when the control valve is open. The cylinder P2 includes a large-diameter inner peripheral surface P21 that accommodates the floating plate P5, a small-diameter inner peripheral surface P22 that accommodates the piston portion P31 of the nozzle needle P3, and a large-diameter inner peripheral surface P21 and a small-diameter inner peripheral surface P22. And a step surface P23 formed on the surface. The step surface P23 is a shoulder surface that abuts when the floating plate P5 moves downward in the figure. The floating plate P5 has a passage P51 that communicates the pressure chamber P4 and the recess P14. The floating plate P5 has an outer peripheral surface P52 that faces the large-diameter inner peripheral surface P21, and a stopper surface P53 that faces the pressure chamber P4 and contacts the step surface P23. A notch P54 is partially formed at the corner between the outer peripheral surface P52 and the stopper surface P53.

When the floating plate P5 is on the upper side in the figure, the floating plate P5 contacts the contact surface P12. At this time, the pressure chamber P4 communicates with the recess P14 through the passage P51. Communication between the pressure chamber P4 and the recess P13 is blocked. On the other hand, when the floating plate P5 is on the lower side in the figure, the floating plate P5 contacts the step surface P23. At this time, the pressure chamber P4 communicates with the recess P13 through the notch P54 and a gap between the outer peripheral surface P52 and the large-diameter inner peripheral surface P21. When the floating plate P5 is on the lower side in the figure, the stopper surface P53 and the step surface P23 are in contact over a wide area.

FIG. 8 is a partial plan view showing the cylinder P2 and the floating plate P5 of the fuel injection device P10 of the comparative example. The notch P54 is formed along the radial direction at a position away from the diameter of the floating plate P5. In this comparative example, a plurality of cutout portions P54 are provided in parallel. As a result, the contact surface P55 between the stopper surface P53 and the step surface P23 has an arc shape. The contact surface P55 can also be regarded as the shape of the end surface of the partial cylinder. The radial width PW5 of the contact surface P55 is slightly smaller than the radial width PW2 of the step surface P23.

  In the shape of the illustrated comparative example, the area of the contact surface P55 between the floating plate P5 as the control member and the step surface P23 is large. The large contact surface P55 generates a large fluid resistance when the floating plate P5 is about to sit on or separate from the stepped surface P23. For this reason, there existed a possibility that the responsiveness of the floating plate P5 might fall. As a result, the expected fuel injection characteristics may not be provided. Further, the large contact surface P55 causes a temperature fluctuation with a large fluid resistance. For this reason, the responsiveness of the floating plate P5 may vary depending on the temperature. As a result, fuel injection characteristics may become unstable.

  The present invention has been made in view of the above problems, and an object thereof is to provide a fuel injection device that exhibits excellent responsiveness.

  Another object of the present invention is to provide a fuel injection device that exhibits stable fuel injection characteristics.

  The present invention employs the following technical means to achieve the above object.

  According to the first aspect of the present invention, there is provided a valve body (40) in which a passage for a high-pressure fuel is formed and a nozzle hole (11) for injecting the high-pressure fuel into a combustion chamber of an internal combustion engine is formed at a tip portion; A valve member (90) that moves in the axial direction of the valve body inside the main body, interrupts the supply of high-pressure fuel to the nozzle hole, and is formed facing the end of the valve member, and acts on the valve member A pressure chamber (34) for controlling the movement of the valve member by regulating the pressure is partitioned, and an inflow passage (31) for allowing high-pressure fuel to flow into the pressure chamber and an outflow passage (32) for allowing fuel to flow out from the pressure chamber. The housing member (50) to be formed, the control member (100) which is arranged in the pressure chamber and is connected to and separated from the housing member, and at least communicates with the inflow path and the pressure chamber, and the control member is moved in the axial direction. Control member A large-diameter inner peripheral surface (81) facing the outer peripheral surface (102), a small-diameter inner peripheral surface (82) having an inner diameter smaller than the outer diameter of the outer peripheral surface of the control member, a large-diameter inner peripheral surface and a small-diameter inner periphery And a cylinder (80) having a step surface (83) provided between the control member and the end surface (104) of the control member. The control member is positioned on the outer side in the radial direction from the small-diameter inner peripheral surface. (104) is provided, and is provided with the protrusion (107,207) which can contact | abut to a level | step difference surface.

  According to this configuration, the control member is accommodated inside the large-diameter inner peripheral surface of the cylinder so as to be movable in the axial direction. The control member is restricted from moving in the axial direction when the end surface abuts on the step surface. On the end surface, a protrusion that can contact the step surface is formed. In addition, the protruding portion is located radially outward from the small-diameter inner peripheral surface. For this reason, the contact part of a protrusion part and a level | step difference surface has a width | variety smaller than the width | variety of the radial direction of a level | step difference surface. As a result, the area of the contact portion can be reduced, and fluid resistance caused by the contact portion can be suppressed.

  According to a second aspect of the present invention, the control member has a recess (106, 206) having an inner diameter (D106, D206) larger than the inner diameter (D82) of the small-diameter inner peripheral surface on the end surface (104), A protruding portion (107, 207) is formed radially outward from the recess. According to this structure, the protrusion formed on the outer side in the radial direction from the small-diameter inner peripheral surface is formed by the concave portion formed in the end surface.

  According to a third aspect of the present invention, the concave portion (106) is formed by a concave surface that forms a corner portion (107) by intersecting the outer peripheral surface (102), and a ridge portion is formed by the corner portion. It is characterized by. According to this configuration, the concave surface intersecting with the outer peripheral surface of the control member is formed on the end surface. A ridge line at a corner formed by the intersection of the concave surface and the outer peripheral surface comes into contact with the step surface. Thereby, the area of a contact part can be made small. Furthermore, the corner | angular part which functions as a protrusion part is arrange | positioned at the outermost side of the end surface of a control member. Thereby, a contact part can be arrange | positioned on the outermost side of an end surface.

  The invention described in claim 4 is characterized in that the concave portion is formed by a circular concave portion (206) that forms a cylindrical portion (207) on the end face, and the protruding portion is formed by the cylindrical portion. According to this structure, the circular recessed part formed in the end surface forms a cylinder part in the end surface. The tip end surface of the cylindrical portion comes into contact with the step surface.

  The invention according to claim 5 is characterized in that the concave portion is formed by a concave curved surface (106). According to this structure, the volume increase of the pressure chamber resulting from a recessed part can be suppressed.

  The invention according to claim 6 is characterized in that the control member is formed with a notch (105) extending over the outer peripheral surface and the end surface. According to this structure, the area of the contact part of a control member and a level | step difference surface can be reduced by a notch part.

  The invention according to claim 7 is characterized in that the notch (105) reaches the radially inner side from the small-diameter inner peripheral surface (82) and forms a passage communicating with the pressure chamber. According to this structure, a channel | path can be formed by a notch part.

  Note that the reference numerals in parentheses described in the claims and the above-described means indicate the correspondence with the specific means described in the embodiments described later as one aspect, and are technical terms of the present invention. It does not limit the range.

1 is a block diagram showing a fuel supply system according to a first embodiment to which the present invention is applied. It is sectional drawing which shows the fuel-injection apparatus of 1st Embodiment. It is a partial expanded sectional view which shows the fuel-injection apparatus of 1st Embodiment. It is a partial top view which shows the fuel-injection apparatus of 1st Embodiment. It is a partial expanded sectional view which shows the fuel-injection apparatus of 2nd Embodiment to which this invention is applied. It is a fragmentary top view which shows the fuel-injection apparatus of 2nd Embodiment. It is a partial expanded sectional view of the fuel-injection apparatus of a comparative example. It is a fragmentary top view which shows the fuel-injection apparatus of a comparative example.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

(First embodiment)
FIG. 1 is a block diagram showing a fuel supply system 1 according to a first embodiment to which the present invention is applied. The fuel supply system 1 uses the fuel injection device 10 according to the first embodiment. The fuel supply system 1 supplies fuel to the internal combustion engine 2. The internal combustion engine 2 is a multi-cylinder diesel engine. A head member 2a of the internal combustion engine 2 defines a combustion chamber 2b. The fuel supply system 1 is a direct injection fuel supply system. The fuel injection device 10 directly injects fuel into the combustion chamber 2b. The fuel supply system 1 includes a fuel tank 3, a feed pump 4, a high-pressure fuel pump 5, a common rail 6, an electronic control unit (ECU: Electronic Control Unit) 7, and a fuel injection device 10.

  The feed pump 4 is an electric pump. The feed pump 4 is accommodated in the fuel tank 3. The feed pump 4 is connected to the high-pressure fuel pump 5 by a fuel pipe 8a. The feed pump 4 gives a predetermined feed pressure to the liquid-phase fuel in the fuel tank 3 and supplies it to the high-pressure fuel pump 5. The fuel pipe 8a can be provided with a pressure regulating valve that adjusts the fuel pressure to a predetermined value.

  The high pressure fuel pump 5 is attached to the internal combustion engine 2. The high pressure fuel pump 5 is driven by the output shaft of the internal combustion engine 2. The high-pressure fuel pump 5 is connected to the common rail 6 by a fuel pipe 8b. The high-pressure fuel pump 5 further applies pressure to the fuel supplied by the feed pump 4 and supplies the fuel to the common rail 6. The high-pressure fuel pump 5 has an electromagnetic valve that is electrically connected to the ECU 7. The opening and closing of the electromagnetic valve is controlled by the ECU 7. The ECU 7 controls the solenoid valve so as to adjust the pressure of the fuel supplied from the high-pressure fuel pump 5 to the common rail 6 to a predetermined pressure.

  The common rail 6 is a tubular member made of a metal material such as chromium / molybdenum steel. The common rail 6 has a plurality of branch portions 6a corresponding to the number of cylinders. One branch portion 6a is connected to one fuel injection device 10 by a fuel pipe forming a supply flow path 8c. The fuel supply system 1 includes a plurality of fuel injection devices 10. The fuel injection device 10 and the high-pressure fuel pump 5 are connected by a fuel pipe that forms a return flow path 8d. The common rail 6 temporarily stores the high-pressure fuel supplied from the high-pressure fuel pump 5. The common rail 6 distributes the high-pressure fuel to the plurality of fuel injection devices 10 via the supply flow path 8c. The common rail 6 has a common rail sensor 6b at one end portion of both end portions in the axial direction. The common rail 6 has a pressure regulator 6c at the other end. The common rail sensor 6b is electrically connected to the ECU 7, detects the pressure and temperature of the high-pressure fuel, and outputs it to the ECU 7. The pressure regulator 6c adjusts the pressure of the high-pressure fuel to a constant level and depressurizes and discharges excess fuel. The surplus fuel that has passed through the pressure regulator 6 c is returned to the fuel tank 3 through a flow path in the fuel pipe 8 e that connects between the common rail 6 and the fuel tank 3.

  The fuel injection device 10 is a fuel injection valve that directly injects high-pressure fuel from the injection hole 11 into the combustion chamber 2b. The fuel injection device 10 includes a valve mechanism that controls injection of high-pressure fuel from the injection hole 11 in accordance with a control signal from the ECU 7. The valve mechanism includes a main valve 12 for intermittently injecting high-pressure fuel and a control valve 13. The fuel injection device 10 uses a part of the high-pressure fuel supplied from the supply flow path 8c in order to drive and control the valve mechanism. The fuel used to drive and control the valve mechanism is discharged to a return flow path 8 d communicating between the fuel injection device 10 and the high pressure fuel pump 5 and returned to the high pressure fuel pump 5. The fuel injection device 10 is inserted into the insertion hole of the head member 2a of the internal combustion engine 2 and attached. The fuel injection device 10 injects high-pressure fuel of about 160 to 220 megapascals (MPa).

  The ECU 7 is configured by a microcomputer or the like. The ECU 7 is electrically connected to a plurality of sensors. The plurality of sensors include the above-described common rail sensor 6b, a rotation speed sensor that detects the rotation speed of the internal combustion engine 2, a throttle sensor that detects the throttle opening, an airflow sensor that detects the intake air intake amount, and an excess pressure that detects the boost pressure. A pressure sensor, a water temperature sensor for detecting the cooling water temperature, an oil temperature sensor for detecting the oil temperature of the lubricating oil, and the like can be included. Based on information from the sensor, the ECU 7 sends electrical signals for controlling the opening and closing of the solenoid valve of the high-pressure fuel pump 5 and the valve mechanism of the fuel injection device 10 to the solenoid valve and the fuel injection device 10 of the high-pressure fuel pump 5. Output.

  FIG. 2 is a cross-sectional view showing the fuel injection device 10 of the first embodiment. The fuel injection device 10 includes an electromagnetic drive unit 20, a body 30, a nozzle needle 90, and a floating plate 100.

  The drive unit 20 is accommodated in the body 30. The drive unit 20 is a pilot type solenoid valve. The drive unit 20 constitutes the control valve 13. The drive unit 20 includes a solenoid 21, a stator 22, a mover 23, a spring 24, a valve seat member 25, and a terminal 26. The terminal 26 is an energizing member. One end of the terminal 26 is exposed from the body 30 to the outside. The other end of the terminal 26 is connected to the solenoid 21. The solenoid 21 is supplied with a pulse current from the ECU 7 via the terminal 26. The solenoid 21 generates a magnetic field when energized. The stator 22 is a cylindrical member made of a magnetic material. The stator 22 guides the magnetic flux generated by the solenoid 21. The mover 23 is a two-stage cylindrical member formed of a magnetic material. The mover 23 is arranged on the distal end side in the axial direction of the stator 22. The mover 23 is attracted toward the stator 22 when the solenoid 21 is excited. The spring 24 is a coil spring. The spring 24 urges the movable element 23 in a direction in which the movable element 23 is separated from the stator 22. The valve seat member 25 forms a pressure control valve 27 together with the control valve seat 52 of the body 30. The valve seat member 25 is provided at the end of the mover 23 in the axial direction. The valve seat member 25 can be seated on the control valve seat portion 52 to prevent fluid from flowing. When the solenoid 21 is not excited, the valve seat member 25 is seated on the control valve seat 52 by the biasing force of the spring 24. When the solenoid 21 is excited, the valve seat member 25 is separated from the control valve seat portion 52.

  The body 30 includes a nozzle body 40, an orifice member 50, a holder 60, a retaining nut 70, and a cylinder 80. The nozzle body 40, the orifice member 50, and the holder 60 are arranged in this order from the tip side where the nozzle hole 11 is provided. The body 30 defines an inflow path 31, an outflow path 32, a main supply path 33, and a pressure chamber 34. The body 30 provides the contact surface 51 exposed to the pressure chamber 34 by the lower surface of the orifice member 50. One end of the inflow channel 31 communicates with the supply channel 8c. The other end of the inflow path 31 communicates with an inflow port 31 a that opens to the contact surface 51. One end of the outflow path 32 communicates with the return flow path 8d via the pressure control valve 27. The other end of the outflow passage 32 communicates with an outflow port 32 a that opens to the contact surface 51. The pressure chamber 34 is partitioned by the cylinder 80, the orifice member 50, and the nozzle needle 90. High-pressure fuel that has passed through the supply flow path 8c can flow into the pressure chamber 34 from the inlet 31a. The fuel in the pressure chamber 34 can flow out to the return flow path 8d via the outflow port 32a.

  The nozzle body 40 is a bottomed cylindrical member made of a metal material such as chromium / molybdenum steel. The nozzle body 40 includes a nozzle needle housing portion 41, a valve seat portion 42, and the injection hole 11. The nozzle needle accommodating portion 41 is a cylindrical hole that is formed along the axial direction of the nozzle body 40 and accommodates the nozzle needle 90. High pressure fuel is supplied into the nozzle needle housing portion 41. The valve seat portion 42 is formed on the bottom wall of the nozzle needle housing portion 41. The valve seat portion 42 is formed so as to contact the tip of the nozzle needle 90. The valve seat portion 42 provides a fixed valve seat for the main valve that interrupts the flow of the high-pressure fuel. The nozzle hole 11 is located on the downstream side of the valve seat portion 42. A plurality of nozzle holes 11 are formed radially from the inside to the outside of the nozzle body 40. By passing through the nozzle hole 11, the high-pressure fuel is atomized and diffused to be easily mixed with air. The nozzle body 40 is also called a nozzle member or a valve body. The nozzle body 40 is a member in which a passage for high-pressure fuel is formed, and an injection hole 11 for injecting high-pressure fuel into the combustion chamber of the internal combustion engine is formed at the tip.

  The cylinder 80 is a cylindrical member made of a metal material. The cylinder 80 defines the pressure chamber 34 together with the orifice member 50 and the nozzle needle 90. The cylinder 80 is disposed in the nozzle needle housing portion 41 so as to be coaxial with the nozzle needle housing portion 41. One end face of the cylinder 80 is disposed on the orifice member 50 side. One end surface of the cylinder 80 is pressed against the contact surface 51 of the orifice member 50. As a result, the cylinder 80 is fixed and held on the orifice member 50. The cylinder 80 is movable with respect to the orifice member 50, but can be viewed as a member belonging to the orifice member 50 as a member that partitions the pressure chamber 34. On the other hand, the cylinder 80 can be viewed as a member belonging to the nozzle body 40 because its radial position is defined by the nozzle body 40 via the nozzle needle 90.

  The orifice member 50 is a columnar member made of a metal material such as chromium / molybdenum steel. The orifice member 50 is disposed and held between the nozzle body 40 and the holder 60. The orifice member 50 forms a contact surface 51, a control valve seat 52, an inflow path 31, an outflow path 32, and a main supply path 33. The abutting surface 51 is formed at the radial center of the end surface of the orifice member 50 on the nozzle body 40 side. The contact surface 51 is surrounded by the cylinder 80 and has a circular shape. The control valve seat portion 52 is formed on the end surface on the holder 60 side of both end surfaces of the orifice member 50 in the axial direction. The control valve seat 52 constitutes a pressure control valve 27 together with the valve seat member 25. The inflow passage 31 is inclined with respect to the central axis of the orifice member 50. The outflow passage 32 extends from the central portion in the radial direction of the contact surface 51 toward the control valve seat portion 52. The outflow passage 32 is inclined with respect to the central axis of the orifice member 50. The main supply path 33 communicates the supply flow path 8 c and the nozzle needle housing portion 41.

  The orifice member 50 has an inflow recess 53, an outflow recess 54, and a double annular contact surface 51 on the surface facing the floating plate 100. The inflow recess 53 is formed in an annular groove shape concentric with the central axis of the orifice member 50. The inflow recess 53 is recessed from the top surface of the contact surface 51. The inflow recess 53 has an inflow port 31a. The outflow recess 54 is formed in a circular groove shape concentric with the central axis of the orifice member 50. The outflow recess 54 is provided at the radial center of the orifice member 50. The outflow recess 54 is recessed in a circular shape from the top surface of the contact surface 51. The inflow recess 53 is located on the outer side in the radial direction than the outflow recess 54. An inner ring of the contact surface 51 is located between the inflow recess 53 and the outflow recess 54. The inflow recess 53 and the outflow recess 54 are partitioned by a flat seal provided by the inner ring of the contact surface 51. The flat seal completely partitions the inflow recess 53 and the outflow recess 54 when the top surface of the contact surface 51 and the floating plate 100 come into contact with each other. An outer ring of the contact surface 51 is located on the outer side in the radial direction from the inflow recess 53. The inflow recess 53 and the nozzle needle housing portion 41 are partitioned by a flat seal provided by the outer ring of the contact surface 51. The flat seal completely partitions the inflow recess 53 and the nozzle needle housing portion 41 when the top surface of the contact surface 51 and the floating plate 100 come into contact with each other.

  The orifice member 50 is also called a housing member or an orifice plate. The orifice member 50 is formed facing the end of the nozzle needle 90 and defines a pressure chamber 34 that controls the movement of the nozzle needle 90 by adjusting the pressure of the fuel acting on the nozzle needle 90. Further, the orifice member 50 forms an inflow path 31 through which high-pressure fuel flows into the pressure chamber 34 and an outflow path 32 through which fuel flows out from the pressure chamber 34.

  The holder 60 is a cylindrical member made of a metal material such as chromium / molybdenum steel. The holder 60 has vertical holes 61 and 62 formed along the axial direction, and a socket part 63. The vertical hole 61 is a fuel flow path that connects the supply flow path 8 c and the inflow path 31. The drive unit 20 is accommodated on the orifice member 50 side of the vertical hole 62. A socket portion 63 is formed on the opposite side of the vertical hole 62 from the orifice member 50 so as to close the opening of the vertical hole 62. One end of the terminal 26 of the drive unit 20 protrudes inside the socket unit 63. The socket part 63 is a connector that can be fitted to a plug connected to the ECU 7. By connecting the socket part 63 and the plug, a pulse current can be supplied from the ECU 7 to the drive part 20.

  The retaining nut 70 is a two-stage cylindrical member made of a metal material. The retaining nut 70 accommodates a part of the nozzle body 40, the orifice member 50, and a part of the holder 60. The retaining nut 70 is screwed into an end portion of the holder 60 close to the orifice member 50. The retaining nut 70 forms a stepped portion 71 on the inner peripheral wall portion. The step portion 71 regulates the movement of the nozzle body 40. When the retaining nut 70 is attached to the holder 60, the nozzle body 40 and the orifice member 50 are pressed against the holder 60 side. The holder 60 and the retaining nut 70 sandwich and fix the nozzle body 40 and the orifice member 50 in the axial direction.

  The nozzle needle 90 is a cylindrical member as a whole formed of a metal material such as high-speed tool steel. The nozzle needle 90 has a piston portion 91, a sliding portion 92, and a seat portion 93. The piston portion 91 is a portion located in the cylinder 80 in the columnar outer peripheral wall of the nozzle needle 90. The piston portion 91 is slidably supported with respect to the inner surface of the cylinder 80 in the cylinder 80. The sliding portions 92 are formed at equal intervals on the outer peripheral surface of the nozzle needle 90. The sliding portion 92 is in contact with the inner surface of the nozzle body 40. The sliding portion 92 guides the nozzle needle 90 so as to be movable in the axial direction within the nozzle body 40. The sheet portion 93 is formed at an end portion on the opposite side to the pressure chamber 34 of both end portions in the axial direction of the nozzle needle 90. The seat portion 93 can be seated on the valve seat portion 42. The seat portion 93 and the valve seat portion 42 constitute a main valve 12 that interrupts the flow of high-pressure fuel supplied into the nozzle needle housing portion 41 to the injection hole 11. An annular flange member 96 is attached to the step portion of the nozzle needle 90. The nozzle needle 90 is also called a valve member. The nozzle needle 90 moves in the axial direction of the nozzle body 40 inside the nozzle body 40, and interrupts the supply of high-pressure fuel to the nozzle hole 11.

  A return spring 97 is arranged in a compressed state between the cylinder 80 and the nozzle needle 90. Since the cylinder 80 is in contact with the orifice member 50, it can be said that the return spring 97 is disposed between the orifice member 50 and the nozzle needle 90. The nozzle needle 90 is urged in the valve closing direction by a return spring 97. The return spring 97 is a coil spring. One end of the return spring 97 in the axial direction is in contact with the flange member 96, and the other end is in contact with the end surface of the cylinder 80. The nozzle needle 90 is linearly reciprocated along the axial direction of the cylinder 80 in response to the pressure difference between the fuel pressure acting on the piston portion 91 and the high-pressure fuel supplied into the nozzle needle housing portion 41. To do. The nozzle needle 90 opens and closes the main valve 12 by seating or separating the seat portion 93 on the valve seat portion 42.

  A floating plate 100 is accommodated in the cylinder 80. The floating plate 100 is a control member that controls the inflow and outflow of fuel into the pressure chamber 34. The floating plate 100 is a disk-shaped member made of a metal material. The floating plate 100 is movably disposed in the pressure chamber 34. The central axis of the floating plate 100 is disposed along the central axis of the cylinder 80. The floating plate 100 is disposed coaxially with the cylinder 80. The floating plate 100 is arranged so as to be reciprocally displaceable mainly in the axial direction thereof. Of the both end faces of the floating plate 100, one end face facing the contact face 51 can be in contact with the contact face 51. A sufficiently large gap is formed between the outer peripheral surface of the floating plate 100 and the cylinder 80 to allow fuel to flow. A communication hole 101 is formed in the center of the floating plate 100 so as to penetrate the floating plate 100 in the axial direction. The communication hole 101 communicates the pressure chamber 34 and the outflow path 32. The communication hole 101 is also a throttle portion. The communication hole 101 restricts the flow rate of the fuel flowing through the communication hole 101.

  When the floating plate 100 is away from the contact surface 51, the fuel that has flowed from the inflow port 31 a passes between the floating plate 100 and the cylinder 80 and flows into the pressure chamber 34. When the floating plate 100 is seated on the contact surface 51, the fuel in the pressure chamber 34 can flow out from the outflow port 32 a via the communication hole 101. When the floating plate 100 is seated on the contact surface 51, the communication between the inlet 31a and the pressure chamber 34 is blocked. The floating plate 100 and the orifice member 50 provide a flow path switching valve that switches between introduction of high-pressure fuel into the pressure chamber 34 and discharge of fuel from the pressure chamber 34.

  The floating plate 100 is a pressure-responsive control member that moves according to the pressure controlled by the pressure control valve 27. The floating plate 100 is disposed in the pressure chamber 34, and at least communicates with the inflow passage 31 and the pressure chamber 34 by being in contact with and away from the orifice member 50. Furthermore, the floating plate 100 is a member whose radial position is defined by the nozzle body 40. The orifice member 50 and the floating plate 100 form a flat seal for interrupting communication between the inflow passage 31 and the pressure chamber 34.

  The plate spring 110 is a coil spring. One end of the plate spring 110 in the axial direction is seated on the end surface of the floating plate 100. The other end of the plate spring 110 in the axial direction is seated on the nozzle needle 90. The plate spring 110 is disposed between the floating plate 100 and the nozzle needle 90 while being contracted in the axial direction. The plate spring 110 biases the floating plate 100 toward the contact surface 51.

  FIG. 3 is a partially enlarged cross-sectional view showing the fuel injection device 10 of the first embodiment. FIG. 4 is a partial plan view showing the cylinder 80 and the floating plate 100 of the fuel injection device 10 of the first embodiment.

  The cylinder 80 is a cylindrical member. The inner surface of the cylinder 80 has a large-diameter inner peripheral surface 81, a small-diameter inner peripheral surface 82, and a step surface 83. The inner diameter of the large-diameter inner peripheral surface 81 is larger than the inner diameter of the small-diameter inner peripheral surface 82. The large-diameter inner peripheral surface 81 is located on the orifice member 50 side in the axial direction of the cylinder 80. An inflow port 31 a and an outflow port 32 a are positioned inside the large-diameter inner peripheral surface 81. The large-diameter inner peripheral surface 81 faces the outer peripheral surface 102 of the floating plate 100. A slight gap is formed between the large-diameter inner peripheral surface 81 and the outer peripheral surface 102. The axial depth of the large-diameter inner peripheral surface 81 is slightly larger than the axial thickness of the floating plate 100. For this reason, the cylindrical space defined by the large-diameter inner peripheral surface 81 allows the floating plate 100 to move slightly in the axial direction. The small-diameter inner peripheral surface 82 is located on the opposite side of the orifice member 50 in the axial direction of the cylinder 80. The small diameter inner peripheral surface 82 has an inner diameter smaller than the outer diameter of the outer peripheral surface 102 of the floating plate 100. The small-diameter inner peripheral surface 82 accommodates a piston portion 91 provided at the end of the nozzle needle 90 so as to be slidable along the axial direction. The small diameter inner peripheral surface 82 provides a sliding surface on the cylinder side. The small-diameter inner peripheral surface 82 forms a cylinder bore. The step surface 83 is an annular flat surface facing the orifice member 50. The step surface 83 is opposed to the radially outer edge of the end surface 104 of the floating plate 100. The step surface 83 is formed between the large diameter inner peripheral surface 81 and the small diameter inner peripheral surface 82. The cylinder 80 is arranged so as to be pressed against the orifice member 50, thereby defining the pressure chamber 34 together with the orifice member 50.

  The piston portion 91 is located in the small diameter inner peripheral surface 82. The piston portion 91 is slidably supported with respect to the small-diameter inner peripheral surface 82. The piston portion 91 defines the pressure chamber 34. The piston part 91 receives the pressure of the fuel in the pressure chamber 34. The piston portion 91 is formed in a cylindrical shape, and forms a spring accommodating portion that accommodates a part of the plate spring 110 therein.

  The floating plate 100 is housed inside the large-diameter inner peripheral surface 81 of the cylinder 80 in the radial direction. A sufficiently large gap is formed between the outer peripheral surface 102 of the floating plate 100 and the large-diameter inner peripheral surface 81 of the cylinder 80 to allow fuel to flow. The floating plate 100 has an end surface 103 facing the orifice member 50 and an end surface 104 facing the step surface 83. The end surface 103 is also called an upper surface. The end surface 104 is also called a lower surface.

  A notch 105 is partially formed on the outer edge of the end face 104 on the radially outer side. The notch 105 is a linear groove that opens across the outer peripheral surface 102 and the end surface 104. The notch 105 forms a linear ridge line on the end face 104 that is located away from the diameter of the floating plate 100 and is parallel to the diameter. A plurality of notches 105 are formed in the floating plate 100. Two notches 105 are formed in the floating plate 100 in parallel with each other. The notch 105 has a predetermined width from the outer peripheral surface 102 in the radial direction and a predetermined depth from the end surface 104 in the axial direction. The width of the notch 105 is larger than the radial width of the step surface 83. The notch 105 reaches radially inward from the small-diameter inner peripheral surface 82 and forms a passage communicating with the pressure chamber 34. For this reason, the fuel that has passed through the gap between the outer peripheral surface 102 and the large-diameter inner peripheral surface 81 can flow into the pressure chamber 34 through the notch 105.

  The end face 104 faces the pressure chamber 34. The floating plate 100 has a ridge that extends along the outer edge of the end surface 104 in the radial direction and protrudes toward the step surface 83. The end face 104 is formed by a recess. The concave portion extends at least from the radially inner side to the radially outer side of the small-diameter inner peripheral surface 82 from the radially inner side thereof. The concave portion is formed by a concave surface that forms a corner portion 107 by intersecting with the outer peripheral surface 102. The concave portion is formed by a concave curved surface 106. The entire end surface 104 is a concave curved surface 106. The concave curved surface 106 extends so as to intersect the outer peripheral surface 102. A corner 107 where the concave curved surface 106 and the outer peripheral surface 102 intersect forms an acute angle in cross section. The corner 107 extends along the outer edge of the end face 104 in the radial direction. The ridge is provided by the corner 107. Since the two notches 105 are formed in the floating plate 100, two arc-shaped corners 107 are formed in the floating plate 100. The top of the corner portion 107 forms a ridge line extending in an arc shape. A ridge portion is formed by the corner portion 107. The corner portion 107 as a protruding portion is formed on the end surface 104 so as to be positioned on the outer side in the radial direction from the small-diameter inner peripheral surface 82, and can contact the step surface 83.

  The diameter D106 of the concave curved surface 106 is larger than the inner diameter D82 of the small-diameter inner peripheral surface 82 (D106> D82). The diameter D106 is equal to the outer diameter of the outer peripheral surface 102. The diameter D106 is slightly smaller than the inner diameter of the large-diameter inner peripheral surface 82. Therefore, the corner 107 is positioned only on the outermost radial direction of the floating plate 100.

  The plate spring 110 is in contact with the concave curved surface 106. Since the concave curved surface 106 is deepest in the central axis of the floating plate 100, the contact position of the plate spring 110 is stably maintained.

  When the floating plate 100 abuts on the step surface 83, the corner portion 107 abuts on the step surface 83. A contact surface 108 between the corner 107 and the step surface 83 corresponds to an arcuate ridgeline. In the drawing, the contact surface 108 is shown by a two-dot chain line.

  The concave surface 106 can be formed by grinding the end surface 104 of the floating plate 100. The concave curved surface 106 can be formed by slightly denting the end surface 104. For this reason, the expansion of the volume of the pressure chamber 34 is suppressed.

  The fuel supply system 1 supplies high-pressure fuel to the fuel injection device 10. The fuel injection device 10 injects fuel in response to a signal from the ECU 7.

  When there is no signal from the ECU 7, the pressure control valve 27 is closed. The high pressure fuel is supplied into the nozzle needle housing portion 41. On the other hand, the high-pressure fuel supplied from the inlet 31 a to the inflow recess 53 acts to lift the floating plate 100 from the contact surface 51. At this time, the pressure in the outflow recess 54 is equal to the pressure in the pressure chamber 34 by the communication hole 101. For this reason, the high-pressure fuel in the inflow recess 53 pushes down the floating plate 100 and flows into the pressure chamber 34. When the pressure in the pressure chamber 34 increases, the floating plate 100 is seated on the contact surface 51. Since the difference between the pressure in the nozzle needle accommodating portion 41 and the pressure in the pressure chamber 34 is small, the nozzle needle 90 is seated on the valve seat portion 42 and stops fuel injection from the injection hole 11.

  When the solenoid 21 is excited by a signal from the ECU 7, the pressure control valve 27 is opened. When the pressure control valve 27 is opened, the fuel in the pressure chamber 34 flows out through the communication hole 101. As a result, the fuel pressure in the pressure chamber 34 decreases. At this time, since the pressure in the outflow recess 54 is low, the floating plate 100 remains seated on the contact surface 51. When the pressure in the pressure chamber 34 decreases, the high-pressure fuel supplied into the nozzle needle housing portion 41 pushes up the nozzle needle 90 toward the pressure chamber 34 at a high speed against the return spring 97. As a result, the nozzle needle 90 is separated from the valve seat portion 42 and fuel injection from the injection hole 11 is started.

  When excitation of the solenoid 21 is stopped by a signal from the ECU 7, the pressure control valve 27 is closed. Thereby, the pressure in the outflow recess 54 becomes equal to the pressure in the pressure chamber 34 by the communication hole 101. As a result, the high-pressure fuel supplied from the inlet 31 a to the inflow recess 53 slightly pushes down the floating plate 100 and flows into the pressure chamber 34. When the pressure in the pressure chamber 34 increases, the floating plate 100 is seated on the contact surface 51. When the pressure in the pressure chamber 34 increases, the nozzle needle 90 is seated on the valve seat portion 42 and fuel injection from the injection hole 11 is stopped.

  According to this embodiment, the contact surface 108 between the floating plate 100 and the cylinder 80 becomes the ridgeline of the corner 107. For this reason, the contact surface 108 can be made small. As a result, it is possible to suppress the resistance of the fuel acting on the floating plate 100 when the floating plate 100 contacts the cylinder 80 and / or when the floating plate 100 moves away from the cylinder 80. For this reason, the responsiveness of the movement of the floating plate 100 is enhanced. In addition, since the contact surface 108 is small, even when the temperature of the fuel changes, the fluctuation of the response of the floating plate 100 is small. For this reason, stable fuel injection characteristics are realized.

(Second Embodiment)
FIG. 5 is a partially enlarged sectional view showing a fuel injection device according to a second embodiment to which the present invention is applied. FIG. 6 is a partial plan view showing the cylinder 80 and the floating plate 100 of the fuel injection device 10 of the second embodiment.

  In the first embodiment, the entire end surface 104 is a concave curved surface 106. Instead, in the second embodiment, the end face 104 is formed by a bottomed cylindrical portion.

Even in this embodiment,
The end face 104 is formed by a circular concave portion 206 and a cylindrical portion 207 that is located radially outward from the circular concave portion 206. The floating plate 100 has a circular concave portion 206 having an inner diameter D206 larger than the inner diameter D82 of the small-diameter inner peripheral surface 82 on the end face 104. The circular recess 206 is provided at the center of the end face 104. The circular recess 206 extends at least from the radially inner side to the radially outer side of the small diameter inner peripheral surface 82 from the smaller diameter inner peripheral surface 82. The inner peripheral surface 206 a of the circular recess 206 is located on the outer side in the radial direction from the small-diameter inner peripheral surface 82. The inner peripheral surface 206 a is located within the radial range of the step surface 83.

  The circular recess 206 forms a cylindrical portion 207 on the end face 104. A plate-like cylinder portion 207 is formed between the inner peripheral surface 206 a and the outer peripheral surface 102. Since the two notches 105 are formed in the floating plate 100, two arc-shaped cylindrical portions 207 are formed in the floating plate 100. The cylinder part 207 is a partial cylinder. The cylindrical portion 207 extends along the outer edge of the end surface 104 in the radial direction. The cylinder part 207 has a flat surface at the tip surface. The distal end surface of the cylindrical portion 207 forms a flat surface extending in an arc shape. The cylinder part 207 forms a protrusion. Therefore, a protrusion is formed on the end face 104 on the outer side in the radial direction from the circular recess 206. The cylindrical portion 207 as the protruding portion is formed on the end surface 104 so as to be positioned on the outer side in the radial direction from the small-diameter inner peripheral surface 82, and can contact the step surface 83.

  The inner diameter D206 of the recess 206 is larger than the inner diameter D82 of the small-diameter inner peripheral surface 82 (D206> D82). The inner diameter D206 is smaller than the outer diameter of the outer peripheral surface 102. Further, the inner diameter D206 is smaller than the inner diameter of the large-diameter inner peripheral surface 82. Therefore, the cylindrical portion 207 is positioned only on the outermost radial direction of the floating plate 100.

  When the floating plate 100 abuts on the step surface 83, the cylindrical portion 207 abuts on the step surface 83. A contact surface 208 between the cylindrical portion 207 and the stepped surface 83 corresponds to an arcuate plane formed at the tip of the cylindrical portion 207. In the drawing, the contact surface 208 is shown by diagonal lines. According to this embodiment, the contact surface 208 between the floating plate 100 and the cylinder 80 becomes the end surface of the cylindrical portion 207 formed only at the radially outer edge of the floating plate 100. For this reason, the contact surface 208 can be made small.

(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 said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. 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.

  For example, instead of the concave curved surface 106, a concave conical surface or a concave frustoconical surface may be adopted. Further, a protruding portion that protrudes toward the pressure chamber 34 may be provided at the radial center portion of the concave curved surface 106 and the circular concave portion 206. In this case, the end face 104 is provided with an annular groove instead of the circular recess 206. The annular groove is defined by an inner edge having a diameter smaller than the inner diameter of the small-diameter inner peripheral surface 82 and an outer edge having a diameter larger than the inner diameter of the small-diameter inner peripheral surface 82. In other words, the annular groove as the recess has a width extending from the radially inner side to the radially outer side of the small-diameter inner peripheral surface 82 from the small-diameter inner peripheral surface 82, and extends along the small-diameter inner peripheral surface 82. As a result, the volume of the pressure chamber 34 can be reduced. Instead of the circular recess 206, a concave curved surface having the same diameter as the diameter D206 of the circular recess 206 may be provided. Thus, the recesses 106 and 206 provided in the floating plate 100 can have various shapes.

  Further, a slight flat surface may be provided at the tip of the corner portion 107. Further, the tip end surface of the tube portion 207 may be slightly inclined to form a corner portion at the tip of the tube portion 207. Thus, the protrusions 107 and 207 provided on the radially outer side of the end face 104 of the floating plate 100 can have various shapes.

  DESCRIPTION OF SYMBOLS 1 Fuel supply system, 10 Fuel injection apparatus, 11 Injection hole, 20 Drive part, 27 Pressure control valve, 30 Body, 34 Pressure chamber, 40 Nozzle body (valve main body), 50 Orifice member (housing member), 60 Holder, 70 Retaining nut, 80 cylinder, 90 nozzle needle (valve member), 97 return spring, 100 floating plate (control member), 110 plate spring, 106 concave curved surface, 107 corner, 108 contact surface, 206 circular concave, 207 cylinder 208 Contact surface.

Claims (7)

A valve body (40) in which a passage for high-pressure fuel is formed and a nozzle hole (11) for injecting the high-pressure fuel into the combustion chamber of the internal combustion engine is formed at the tip;
A valve member (90) that moves in the axial direction of the valve body inside the valve body and interrupts the supply of the high-pressure fuel to the nozzle hole;
A pressure chamber (34) is formed facing the end of the valve member and controls the movement of the valve member by adjusting the pressure of fuel acting on the valve member, and the pressure chamber includes the pressure chamber (34). A housing member (50) that forms an inflow passage (31) through which high-pressure fuel flows in and an outflow passage (32) through which fuel flows out from the pressure chamber;
A control member (100) that is disposed in the pressure chamber, and that connects and disconnects at least the inflow path and the pressure chamber by contacting and separating from the housing member;
The control member is movably accommodated in the axial direction, and has a large-diameter inner peripheral surface (81) facing the outer peripheral surface (102) of the control member and an inner diameter smaller than the outer diameter of the outer peripheral surface of the control member. A cylinder (80) having a small-diameter inner peripheral surface (82) and a step surface (83) provided between the large-diameter inner peripheral surface and the small-diameter inner peripheral surface and facing an end surface (104) of the control member. )
The control member includes protrusions (107, 207) that are formed on the end surface (104) and located on the outer side in the radial direction from the inner peripheral surface of the small diameter, and that can contact the step surface. Fuel injection device.   The control member has concave portions (106, 206) having an inner diameter (D106, D206) larger than the inner diameter (D82) of the small-diameter inner peripheral surface on the end surface (104), and is radially outside the concave portion. The fuel injection device according to claim 1, wherein the protrusion (107, 207) is formed in the protrusion.   The said recessed part (106) is formed by the concave surface which forms a corner | angular part (107) by crossing the said outer peripheral surface (102), The said protrusion is formed by the said corner | angular part. Item 3. The fuel injection device according to Item 2.   The fuel injection according to claim 2, wherein the concave portion is formed by a circular concave portion (206) that forms a cylindrical portion (207) on the end surface, and the protruding portion is formed by the cylindrical portion. apparatus.   The fuel injection device according to any one of claims 2 to 4, wherein the concave portion is formed by a concave curved surface (106).   The fuel injection device according to any one of claims 1 to 5, wherein the control member is formed with a notch (105) extending over the outer peripheral surface and the end surface.   The fuel injection according to claim 6, wherein the notch (105) reaches a radially inner side from the small-diameter inner peripheral surface (82) and forms a passage communicating with the pressure chamber. apparatus.

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