JP2011185223A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device having superior temperature characteristic by suppressing fluctuation of the time required by the start of the displacement of a valve member dependent on the temperature. <P>SOLUTION: In the fuel injection device, a control body 40 has a pressure control chamber 53, a flow-in port 52a for allowing the fuel to flow in the control chamber 53, and a flow-out port 54a for allowing the fuel to flow out from the control chamber 53. A floating plate 70 for blocking the flow-in port 52a from the pressure control chamber 53 by pressing an opening wall surface 90 by the pressure of the fuel is arranged in the pressure control chamber 53. The floating plate 70 has a recessed part 72 in a pressure-bearing surface 77 opposite to a nozzle needle 60, and the nozzle needle 60 has a projecting part 62 on a valve bearing surface 61 opposite to the pressure-bearing surface 77. In a condition in which the nozzle needle 60 and the floating plate 70 are brought closest to each other, the projecting part 62 is located within the recessed part 72, and a fore end part 62a thereof is separated from a bottom part 72a of the recessed part 72. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fuel injection device that opens and closes a valve unit to control injection from a nozzle hole of supplied fuel supplied from a supply channel, and discharges part of the supplied fuel to a return channel in accordance with the control. About.

  2. Description of the Related Art Conventionally, a fuel injection device is known that includes a control body having a pressure control chamber and a valve member that opens and closes a valve portion in accordance with the pressure of fuel in the pressure control chamber. In such a fuel injection device, in the pressure control chamber of the control body, an inflow port through which the fuel flowing through the supply flow channel flows and an outflow port through which the fuel is discharged to the return flow channel are opened. In addition, the pressure of the fuel in the pressure control chamber is controlled by a pressure control valve that switches communication between the outlet and the return flow path.

  As a kind of such a fuel injection device, for example, Patent Document 1 and Patent Document 2 disclose a configuration in which a pressure member that further reciprocally moves in the pressure control chamber is further provided. When the outlet and the return channel communicate with each other by the pressure control valve, the pressing member is sucked by the flow of the fuel from the pressure control chamber toward the outlet, and the opening wall surface of the outlet is opened. Pressing is performed so as to block communication between the inlet, the pressure control chamber, and the outlet. The supply of fuel into the pressure control chamber is interrupted by the pressing of the opening wall surface by the pressing member. The fuel in the pressure control chamber is discharged to the return flow path via the restriction hole and the outlet while the discharge amount is restricted by the restriction hole extending in the pressing member. When the fuel is discharged from the pressure control chamber and the fuel pressure in the pressure control chamber falls below a predetermined pressure, the valve member starts to be displaced and opens the valve portion.

JP-A-6-108948 German Patent Invention No. 19156565

  In general, the flow rate of the fluid flowing through the flow path varies depending on the temperature of the fluid. The temperature dependence of the flow rate becomes more prominent as the flow channel area is smaller and the flow channel length is longer. Here, the pressing members of Patent Literature 1 and Patent Literature 2 have a concave portion that is recessed from the end surface on one end surface in the axial direction. The present inventors partially enlarge the flow path area of the restriction hole in which the recess extends toward the outlet, and shorten the flow path length of the part where the flow path area is minimum in the restriction hole. Focused on the point. By forming such a concave portion, the temperature-dependent fluctuation of the fuel flow rate flowing through the restriction hole is suppressed. Therefore, the time required until a predetermined amount of fuel is discharged from the pressure control chamber via the restriction hole and the displacement of the valve member is started can hardly be changed.

  However, the volume of the pressure control chamber is increased by forming the recess in the pressing member. Then, the amount of fuel that must be discharged from the pressure control chamber to start the reciprocal displacement of the valve member also increases. Therefore, even if the variation depending on the temperature of the flow rate of fuel flowing through the restriction hole is suppressed, the time required for starting the displacement of the valve member varies as the amount of fuel to be discharged increases.

  In order to suppress an increase in the volume of the pressure control chamber due to the formation of the recess in the pressing member, it is also conceivable to narrow the interval between the pressing member and the valve member. However, since the pressing member and the valve member are configured to reciprocate, they may collide with each other due to the reciprocating displacement. In order to reliably operate the valve member and the pressing member, it is difficult to reduce the volume of the pressure control chamber by narrowing the interval between the pressing member and the valve member.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injection device with excellent temperature characteristics in which fluctuations depending on the temperature of the time required for starting the displacement of the valve member are suppressed. Is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, the valve portion for controlling the injection of the supply fuel supplied from the supply flow path from the injection hole is opened and closed, and one of the supply fuel is controlled in accordance with the control. Injection device for discharging the part to the return flow path, the fuel flowing through the supply flow path flows in from the inlet, the pressure control chamber for discharging the fuel via the outlet, and the pressure A control body having an opening wall surface that is exposed to the control chamber and has an inlet and an outlet open, a pressure control valve that switches communication and blocking between the outlet and the return flow path, and controls the pressure of the fuel in the pressure control chamber; A valve receiving surface exposed to the pressure control chamber, and a reciprocating displacement according to the fuel pressure received by the valve pressure receiving surface, thereby opening and closing the valve portion, and in the pressure control chamber in the direction of the displacement axis of the valve member Along the axis of displacement When there is a pressure receiving surface facing the pressure receiving surface, a restriction hole extending from the pressure receiving surface toward the outlet, and when the outlet and the return channel communicate with each other by the pressure control valve, the inlet and the pressure control chamber communicate with each other When the opening wall surface is pressed so as to block the flow, the amount of fuel flowing from the pressure control chamber to the outlet is limited by the restriction hole, and when the outlet and the return flow path are blocked by the pressure control valve, the inlet A pressing member that is displaced so as to be at least partially separated from the opening wall surface so as to open to the pressure control chamber, and the pressing member is recessed from the pressure receiving surface in a direction away from the valve pressure receiving surface, and the flow passage area of the restriction hole The valve member protrudes from the valve pressure-receiving surface toward the pressure-receiving surface, and the valve member and the pressure member are positioned in the recess and in the protruding direction with the valve member and the pressing member being closest to each other. The tip is separated from the bottom of the recess. A fuel injection apparatus characterized by having a convex portion.

  According to the present invention, the concave portion that is recessed from the pressure receiving surface in the direction away from the valve pressure receiving surface is formed in the pressing member, but the increase in the volume of the pressure control chamber due to the formation is increased from the valve pressure receiving surface to the pressure receiving surface. It is suppressed by forming the convex part which protrudes toward. In addition, the convex portion is located in a concave portion that is recessed from the pressure receiving surface in a direction away from the valve pressure receiving surface in a state in which the valve member and the pressing member are closest to each other. Under this state, the front end portion in the protruding direction of the convex portion is separated from the bottom portion of the concave portion. Thus, the convex part of a valve member does not collide with the press pressure-receiving surface of a press member by the relative displacement of the said valve member and a press member. Therefore, an increase in the volume of the pressure control chamber is suppressed while allowing reliable operation of the valve member and the pressing member.

  The amount of fuel discharged from the pressure control chamber required to start the reciprocal displacement of the valve member can be kept small by suppressing an increase in the volume of the pressure control chamber. Therefore, even if the flow rate of the fuel flowing through the restriction hole varies depending on the temperature of the fuel, since the amount of fuel to be discharged is small, the variation in time required for starting the displacement of the valve member can be suppressed. .

  As described above, the pressure member presses the opening wall surface together with the action of suppressing the variation depending on the temperature of the fuel flow rate flowing through the restriction hole due to the enlargement of a part of the flow passage area of the restriction hole by the concave portion, and then the valve The fluctuation depending on the fuel temperature in the time until the start of displacement of the member is reliably suppressed. Therefore, a fuel injection device having excellent temperature characteristics is realized.

  In the second aspect of the present invention, the minimum flow area of the fuel flow path formed between the concave portion and the convex portion by the relative displacement of the pressing member and the valve member in the direction of approaching each other is the restriction hole. It is characterized by being larger than the minimum flow path area.

  According to the present invention, when the pressing member and the valve member are displaced in the direction approaching each other, the fuel located between the pressing pressure receiving surface and the valve receiving surface is formed between the concave portion and the convex portion. Flowing through the fuel flow path and through the restriction hole. Since the minimum flow path area of the fuel flow path is larger than the minimum flow path area of the restriction hole, the flow rate of the fuel discharged from the pressure control chamber is not easily limited by the fuel flow path. Therefore, it is possible to avoid a situation in which the temperature-dependent fluctuation of the flow rate passing through the fuel flow path affects the time required to start the displacement of the valve member. Therefore, the temperature characteristics of the fuel injection device can be reliably improved.

  In the invention according to claim 3, the control body restricts displacement of the pressing member in the direction close to the valve member, and valve restriction restricts the displacement of the valve member in the direction close to the pressing member. And a portion.

  According to this invention, the pressing member is restricted by the pressing restricting portion of the control body from being displaced in the direction approaching the valve member. In addition, the displacement of the valve member in the direction approaching the pressing member is restricted by the valve restricting portion of the control body. As described above, the flow passage area of the fuel flow passage formed between the concave portion and the convex portion in a state where the pressing member and the valve member are closest to each other can be reliably ensured. Therefore, the situation where the minimum flow path area of the fuel flow path becomes smaller than the minimum flow path area of the restriction hole can be surely avoided by appropriate arrangement of the pressing restriction part and the valve restriction part. Therefore, the temperature characteristic of the fuel injection device is further improved.

  Here, as described above, when the flow of fuel from between the pressure receiving surface and the valve pressure receiving surface to the restriction hole is restricted between the concave portion and the convex portion, the time required to start the displacement of the valve member is The flow rate of the fuel flowing between the concave portion and the convex portion varies depending on the temperature. Accordingly, the invention according to claim 4 forms an axial groove of the recess along the displacement axis direction on the inner peripheral wall around the displacement axis in the recess. According to a fifth aspect of the present invention, the axial groove of the convex portion along the displacement axis direction is formed on the outer peripheral wall around the displacement axis in the convex portion. In these inventions, the fuel located between the pressure receiving surface and the valve pressure receiving surface is composed of an axial groove formed in the inner peripheral wall of the concave portion and an axial groove formed in the outer peripheral wall of the convex portion. , At least one of the inside can be distributed. Therefore, the fuel can smoothly flow between the concave portion and the convex portion and reach the restriction hole. As described above, it is possible to avoid a situation in which fluctuation due to temperature affects the time required for starting the displacement of the valve member with respect to the flow rate flowing between the concave portion and the convex portion. Therefore, the temperature characteristics of the fuel injection device can be reliably improved.

  The invention according to claim 6 is characterized in that the pressing pressure receiving surface is formed with a radial groove of a recess extending from the outer edge of the pressing pressure receiving surface toward the recess. Further, the invention according to claim 8 is characterized in that a convex pressure radial groove extending from the outer edge of the valve pressure receiving surface toward the convex portion is formed on the valve pressure receiving surface.

  In the configuration in which the volume of the pressure control chamber is reduced, when the pressing member and the valve member are relatively displaced in the direction in which they are close to each other, the distance between the pressing pressure receiving surface and the valve receiving surface becomes very small. Therefore, the flow rate of the fuel discharged from the pressure control chamber may be limited between the pressure receiving surface and the valve pressure receiving surface. However, even if the gap between the pressure receiving surface and the valve pressure receiving surface is very small by forming radial grooves extending from the respective outer edges toward the concave or convex portions on the pressure receiving surface or the valve pressure receiving surface. The fuel can flow through at least one of the radial groove of the concave portion and the radial groove of the convex portion. Therefore, the fuel can reach the restriction hole via the space between the concave portion and the convex portion without restricting the flow between the pressure pressure receiving surface and the valve pressure receiving surface. As described above, it is possible to avoid a situation in which fluctuation due to temperature affects the time required for starting the displacement of the valve member with respect to the flow rate flowing between the pressure receiving surface and the valve pressure receiving surface. Therefore, the temperature characteristics of the fuel injection device can be reliably improved.

  In the invention according to claim 7, in the recess, the inner peripheral wall around the displacement axis is formed with an axial groove of the recess along the displacement axis direction, and the axial groove of the recess is continuous with the radial groove of the recess. It is characterized by doing. Further, in the invention according to claim 9, the axial groove of the convex portion along the displacement axis direction is formed on the outer peripheral wall around the displacement axis in the convex portion, and the axial groove of the convex portion is the convex portion. Continuous with the radial groove.

  According to these inventions, the radial groove of the concave portion and the radial groove of the convex portion are formed in the axial groove of the concave portion and the axial groove of the convex portion, which ensures the fuel flow between the concave portion and the convex portion. As a result, the fuel that has flowed through the inside of each radial groove is supplied to the inside of each axial groove. As described above, since the action of each axial groove for smoothly flowing the fuel between the concave portion and the convex portion is enhanced by each radial groove, the valve member is caused by the variation due to temperature with respect to the flow rate flowing between the concave portion and the convex portion. The situation of changing the time required until the start of the displacement can be surely avoided. Therefore, the temperature characteristics of the fuel injection device can be improved more reliably.

  The invention according to claim 10 is characterized in that the convex portion is detached from the concave portion by relative displacement of the pressing member and the valve member in a direction away from each other. The invention according to claim 11 is characterized in that the distal end portion of the convex portion is located in the concave portion in a state where the pressing member and the valve member are most separated from each other. As in these inventions, in the state in which the pressing member and the valve member are relatively displaced in the most separated direction, the convex portion may be detached from the concave portion, and the tip portion is positioned in the concave portion. Also good.

  In the invention according to claim 12, the pressing pressure receiving surface forms a biasing recess by recessing the periphery of the recess in a direction away from the valve pressure receiving surface, and the valve pressure receiving surface presses the periphery of the protrusion. The urging member further includes a urging member that urges the pressing member toward the opening wall surface with respect to the valve member, the urging member being pressed in the displacement axis direction. The end on the surface side is fitted into the urging concave portion, and the end on the valve pressure receiving surface side is fitted onto the urging convex portion in the displacement axis direction.

  As in the present invention, the fuel injection device may further include a biasing member that biases the pressing member toward the opening wall surface with respect to the valve member. In the form including such a biasing member, when the position of the biasing member is shifted along the pressure receiving surface or the valve pressure receiving surface, the displacement axis direction of the pressing member along the displacement axis direction of the valve member is A situation in which the valve member tilts with respect to the direction of the displacement axis may occur. The inclination of the displacement axis of the pressing member may cause a space that should be formed between the concave portion and the convex portion to disappear, and may be a factor that hinders the passage of fuel between the concave portion and the convex portion. Therefore, the end portion on the pressure receiving surface side is fitted in the biasing recess portion formed by the pressure receiving surface, and the end portion on the valve pressure receiving surface side is fitted on the biasing convex portion formed by the valve pressure receiving surface. Accordingly, the occurrence of deviation along the pressure receiving surface or the valve pressure receiving surface of the urging member can be suppressed. Therefore, the flow path through which the fuel can pass can be reliably maintained between the concave portion and the convex portion. Therefore, the temperature characteristic in the fuel injection device including the urging member can be reliably improved by forming the urging concave portion and the urging convex portion that suppress the deviation of the urging member.

It is a lineblock diagram of a fuel supply system provided with a fuel injection device by a first embodiment of the present invention. 1 is a longitudinal sectional view of a fuel injection device according to a first embodiment of the present invention. It is the figure which expanded the vicinity of the characteristic part of the fuel-injection apparatus by 1st embodiment of this invention. It is the figure which expanded further the characteristic part of the fuel-injection apparatus by 1st embodiment of this invention, Comprising: (a) It is a figure which shows the state displaced relatively in the direction which a floating plate and a nozzle needle mutually space | interval, (b FIG. 4 is a diagram showing a state in which the floating plate and the nozzle needle are relatively displaced in the direction of approaching each other. It is a figure which shows the correlation with the temperature in a fuel, and a viscosity coefficient. It is a figure which shows the modification of FIG. It is a figure which shows the modification of FIG. It is a figure which shows the modification of FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows a fuel supply system 10 in which a fuel injection device 100 according to a first embodiment of the present invention is used. The fuel injection device 100 of this embodiment is a so-called direct injection fuel supply system that directly injects fuel into the combustion chamber 22 of the diesel engine 20 that is an internal combustion engine.

  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, a fuel injection device 100, and the like.

  The feed pump 12 is an electric pump and is accommodated in the fuel tank 11. The feed pump 12 applies a feed pressure that is higher than the vapor pressure of the fuel to the fuel stored in the fuel tank 11. The feed pump 12 is connected to the high-pressure fuel pump 13 by a fuel pipe 12 a and supplies the high-pressure fuel pump 13 with fuel in a liquid phase state to which a predetermined feed pressure is applied. The fuel pipe 12a is provided with a pressure regulating valve (not shown), and the pressure of the fuel supplied to the high pressure fuel pump 13 is maintained at a predetermined value by the pressure regulating valve.

  The high-pressure fuel pump 13 is attached to a diesel engine and is driven by power from the output shaft of the diesel engine. The high-pressure fuel pump 13 is connected to the common rail 14 by a fuel pipe 13 a, applies further pressure to the fuel supplied by the feed pump 12, and supplies the fuel to the common rail 14. In addition, the high pressure fuel pump 13 has a solenoid valve (not shown) electrically connected to the engine control device 17. The pressure of the fuel supplied from the high-pressure fuel pump 13 to the common rail 14 is controlled to a predetermined pressure by the opening / closing control of the electromagnetic valve by the engine control device 17.

  The common rail 14 is a tubular member made of a metal material such as chromium / molybdenum steel, and has a plurality of branch portions 14a corresponding to the number of cylinders per bank of the diesel engine. Each of the plurality of branch portions 14a is connected to the fuel injection device 100 by a fuel pipe that forms a supply flow path 14d. The fuel injection device 100 and the high-pressure fuel pump 13 are connected by a fuel pipe that forms a return flow path 14f. With the above configuration, the common rail 14 temporarily stores the fuel supplied in a high pressure state by the high-pressure fuel pump 13, and distributes the fuel to the plurality of fuel injection devices 100 via the supply flow path 14d while maintaining the pressure. In addition, the common rail 14 has a common rail sensor 14b at one end of the both ends in the axial direction and a pressure regulator 14c at the other end. The common rail sensor 14 b is electrically connected to the engine control device 17, detects the fuel pressure and temperature, and outputs the detected fuel pressure and temperature to the engine control device 17. The pressure regulator 14c keeps the fuel pressure in the common rail 14 constant, and depressurizes and discharges excess fuel. The surplus fuel that has passed through the pressure regulator 14 c is returned to the fuel tank 11 through a flow path in the fuel pipe 14 e that connects the common rail 14 and the fuel tank 11.

  The fuel injection device 100 is a device that injects the supplied fuel with an increased pressure supplied through the branch portion 14 a of the common rail 14 from the injection hole 44. Specifically, the fuel injection device 100 is a valve that controls the injection of the supply fuel supplied from the high-pressure fuel pump 13 through the supply passage 14 d from the injection hole 44 in accordance with a control signal from the engine control device 17. Part 50 is provided. In addition, in this fuel injection device 100, a part of the supplied fuel supplied from the supply flow path 14d and the excess fuel not injected from the injection hole 44 is supplied to the fuel injection device 100 and the high-pressure fuel pump. 13 is discharged to a return flow path 14 f that communicates with 13 and returned to the high-pressure fuel pump 13. The fuel injection device 100 is inserted and attached to an insertion hole of a head member 21 that is a part of a combustion chamber 22 of the diesel engine 20. A plurality of fuel injection devices 100 are arranged for each combustion chamber 22 of the diesel engine 20, and fuel is injected directly into the combustion chamber 22, specifically at an injection pressure of about 160 to 220 megapascals (MPa). To do.

  The engine control device 17 is configured by a microcomputer or the like. In addition to the common rail sensor 14b described above, the engine control device 17 includes a rotation speed sensor that detects the rotation speed of the diesel engine 20, a throttle sensor that detects the throttle opening, an airflow sensor that detects the intake air intake amount, and a boost pressure. It is electrically connected to various sensors such as a supercharging pressure sensor for detecting, a water temperature sensor for detecting the cooling water temperature, and an oil temperature sensor for detecting the oil temperature of the lubricating oil. Based on information from each of these sensors, the engine control device 17 sends an electrical signal for controlling the opening and closing of the solenoid valve of the high pressure fuel pump 13 and the valve portion 50 of each fuel injection device 100 to the high pressure fuel pump 13. Output to the solenoid valve and each fuel injection device 100.

  Next, the configuration of the fuel injection device 100 will be described with reference to FIGS. 2 and 3.

  The fuel injection device 100 includes a control valve drive unit 30, a control body 40, a nozzle needle 60, and a floating plate 70.

  The control valve drive unit 30 is accommodated in the control body 40. The control valve drive unit 30 includes a terminal 32, a solenoid 31, a stator 36, a mover 35, a spring 34, and a valve seat member 33. The terminal 32 is formed of a metal material having electrical conductivity, and one end of the both ends in the extending direction is exposed to the outside from the control body 40, and the other end is connected to the solenoid 31. Yes. The solenoid 31 is wound in a spiral shape and receives supply of a pulse current from the engine control device 17 via the terminal 32. The solenoid 31 receives this current supply to generate a magnetic field that circulates along the axial direction. The stator 36 is a cylindrical member made of a magnetic material and magnetizes in a magnetic field generated by the solenoid 31. The mover 35 is a two-stage columnar member made of a magnetic material, and is disposed on the axial front end side of the stator 36. The mover 35 is attracted to the proximal side in the axial direction by a magnetized stator 36. The spring 34 is a coil spring in which a metal wire is wound in a circular shape, and biases the mover 35 in a direction in which the mover 35 is separated from the stator 36. The valve seat member 33 forms a pressure control valve 80 together with a later-described control valve seat 47a of the control body 40. The valve seat member 33 is provided on the opposite side of the stator 36 in the axial direction of the mover 35 and is seated on the control valve seat 47a. When the magnetic field is not formed by the solenoid 31, the valve seat member 33 is seated on the control valve seat portion 47 a by the urging force of the spring 34. When a magnetic field is formed by the solenoid 31, the valve seat member 33 is separated from the control valve seat portion 47a.

  The control body 40 includes a nozzle body 41, a cylinder 56, a valve body 46, a holder 48, and a retaining nut 49. The nozzle body 41, the valve body 46, and the holder 48 are arranged in this order from the leading end side in the insertion direction to the head member 21 (see FIG. 1) where the injection hole 44 is formed. The control body 40 is formed with an inflow path 52, an outflow path 54, a pressure control chamber 53, and an opening wall surface 90 exposed to the pressure control chamber 53. The inflow path 52 communicates with the supply flow path 14d (see FIG. 1) connected to the high-pressure fuel pump 13, the common rail 14, and the like, and an inflow port 52a that is the flow path end of the inflow path 52 is opened in the opening wall surface 90. I am letting. Further, the outflow passage 54 communicates with the return flow path 14f (see FIG. 1) connected to the high-pressure fuel pump 13, and an outlet 54a that is a flow path end of the outflow path 54 is opened to the opening wall surface 90. Yes. The pressure control chamber 53 is partitioned by a cylinder 56 or the like, and fuel that has passed through the supply flow path 14d (see FIG. 1) flows in from the inlet 52a, and passes through the outlet 54a to the return path 14f (see FIG. 1). To discharge the fuel.

  The nozzle body 41 is a bottomed cylindrical member made of a metal material such as chromium / molybdenum steel. The nozzle body 41 has a nozzle needle housing portion 43, a valve seat portion 45, and an injection hole 44. The nozzle needle accommodating portion 43 is a cylindrical hole that is formed along the axial direction of the nozzle body 41 and accommodates the nozzle needle 60. High-pressure fuel is supplied to the nozzle needle housing portion 43 from the high-pressure fuel pump 13 and the common rail 14 (see FIG. 1). The valve seat portion 45 is formed on the bottom wall of the nozzle needle housing portion 43 and contacts the tip of the nozzle needle 60. The nozzle holes 44 are located on the opposite side of the valve body 46 with the valve seat 45 interposed therebetween, and a plurality of the nozzle holes 44 are formed radially from the inside to the outside of the nozzle body 41. By passing through the nozzle hole 44, the high-pressure fuel is atomized and diffused to be easily mixed with air.

  The cylinder 56 is made of a metal material and is a cylindrical member that partitions the pressure control chamber 53 together with the valve body 46 and the nozzle 60 together with the needle 60. The cylinder 56 is disposed in the nozzle needle housing portion 43 so as to be coaxial with the nozzle needle housing portion 43. In the cylinder 56, the end surface in the axial direction on the valve body 46 side is held by the valve body 46.

  The cylinder 56 forms a control wall surface portion 57, a cylinder sliding portion 59, a plate stopper portion 58a, and a needle stopper portion 58b by the inner wall surface. The control wall surface portion 57 is located on the valve body 46 side in the axial direction of the cylinder 56 and surrounds the opening wall surface 90. The cylinder sliding portion 59 is located on the opposite side of the valve body 46 in the axial direction of the cylinder 56, and slides the nozzle needle 60 along the axial direction. The inner diameter of the cylinder sliding portion 59 is reduced with respect to the inner diameter of the control wall surface portion 57. The plate stopper portion 58 a is a step portion formed by a difference in inner diameter between the cylinder sliding portion 59 and the control wall surface portion 57, and faces the floating plate 70 in the displacement axis direction of the plate 70. The plate stopper portion 58 a regulates the displacement of the floating plate 70 in the direction approaching the nozzle needle 60. The needle stopper portion 58b is formed on the side opposite to the control wall surface portion 57 with respect to the cylinder sliding portion 59 in the displacement axis direction. The needle stopper portion 58 b faces in the direction opposite to the plate stopper portion 58 a in the displacement axis direction, and restricts the displacement of the nozzle needle 60 in the direction approaching the floating plate 70.

  The valve body 46 is made of a metal material such as chrome / molybdenum steel and is a cylindrical member that is held between the nozzle body 41 and the holder 48. The valve body 46 forms a control valve seat 47 a, an opening wall surface 90, an outflow path 54, and an inflow path 52. The control valve seat portion 47a is formed on the end surface on the holder 48 side of both end surfaces in the axial direction of the valve body 46, and constitutes the pressure control valve 80 together with the valve seat member 33 and the like of the control valve drive unit 30. The opening wall surface 90 is a flat surface formed at the radial center of the end surface of the valve body 46 on the nozzle body 41 side. The opening wall surface 90 is surrounded by a cylindrical cylinder 56 and has a circular shape. The outflow channel 54 extends from the radial center of the opening wall surface 90 toward the control valve seat 47a. The outflow passage 54 is inclined with respect to the axial direction of the valve body 46. The inflow passage 52 extends from the radially outer side of the outflow passage 54 in the opening wall surface 90 toward the end surface forming the control valve seat portion 47a. The inflow passage 52 is inclined with respect to the axial direction of the valve body 46.

  Further, the valve body 46 has an outflow recess 97 that forms a recessed outlet 54 a from the opening wall surface 90. Further, the valve body 46 has an inflow recess 94 that forms a recessed inlet 52 a from the opening wall surface 90. The outflow recess 97 is recessed in a circular shape at the radial center of the opening wall surface 90. The inflow recess 94 is located radially outside the outflow recess 97 on the opening wall surface 90 and is concentric with the outflow recess 97 and recessed in an annular shape. The outflow recess 97 and the inflow recess 94 are independent of each other.

  The holder 48 is a cylindrical member made of a metal material such as chrome / molybdenum steel, and has vertical holes 48a and 48b formed along the axial direction, and a socket portion 48c. The vertical hole 48 a is a fuel flow path that connects the supply flow path 14 d (see FIG. 1) and the inflow path 52. On the other hand, the control valve drive unit 30 is accommodated on the valve body 46 side of the vertical hole 48b. In addition, a socket portion 48c is formed on the opposite side of the vertical hole 48b from the valve body 46 so as to close the opening of the vertical hole 48b. One end of the terminal 32 of the control valve drive unit 30 protrudes inside the socket portion 48c, and can be fitted to a plug portion (not shown) connected to the engine control device 17. According to the connection between the socket portion 48c and a plug portion (not shown), it is possible to supply a pulse current from the engine control device 17 to the control valve drive portion 30.

  The retaining nut 49 is a two-stage cylindrical member made of a metal material. The retaining nut 49 is screwed to the valve body 46 side of the holder 48 while accommodating a part of the nozzle body 41 and the valve body 46. In addition, the retaining nut 49 forms a stepped portion 49a at the inner peripheral wall portion. The stepped portion 49 a presses the nozzle body 41 and the valve body 46 toward the holder 48 by attaching the retaining nut 49 to the holder 48. As a result, the retaining nut 49 holds the nozzle body 41 and the valve body 46 together with the holder 48.

  The nozzle needle 60 is formed in a cylindrical shape as a whole by a metal material such as high-speed tool steel, and includes a seat portion 65, a valve pressure receiving surface 61, a needle sliding portion 63, a needle locking portion 68, a return spring 66, and A collar member 67 is provided. The seat portion 65 is formed at an end portion on the opposite side to the pressure control chamber 53 among both end portions of the nozzle needle 60 in the axial direction, and is seated on the valve seat portion 45 of the control body 40. This seat portion 65 constitutes a valve portion 50 together with the valve seat portion 45 for switching communication and blocking of the high-pressure fuel supplied into the nozzle needle housing portion 43 to the injection hole 44. The valve pressure receiving surface 61 is formed by an end portion on the side of the pressure control chamber 53 that is opposite to the seat portion 65 among both end portions in the axial direction of the nozzle needle 60. The valve pressure receiving surface 61 divides the pressure control chamber 53 together with the opening wall surface 90 and the control wall surface portion 57 and receives the fuel pressure in the pressure control chamber 53.

  The needle sliding portion 63 is a portion of the cylindrical outer peripheral wall of the nozzle needle 60 that is located closer to the valve pressure receiving surface 61 than the control wall surface portion 57. The needle sliding portion 63 is slidably supported with respect to a cylinder sliding portion 59 formed by the inner peripheral wall of the cylinder 56. The flange member 67 is an annular member that is fitted on the outer peripheral wall portion of the nozzle needle 60 and is held by the nozzle needle 60. The needle locking portion 68 is formed on the axial sheet portion 65 side with respect to the needle sliding surface 63 and is a step portion formed by increasing the outer diameter of the nozzle needle 60. The needle locking portion 68 forms a surface facing the needle stopper portion 58 b of the cylinder 56 in the displacement axis direction of the nozzle needle 60. By the needle locking portion 68 being locked to the needle stopper portion 58b, the displacement of the nozzle needle 60 in the direction approaching the floating plate 70 is restricted.

  The nozzle needle 60 is biased toward the valve unit 50 by a return spring 66. The return spring 66 is a coil spring in which a metal wire is wound around. The return spring 66 is seated at one end in the axial direction on the surface of the flange member 67 on the pressure control chamber 53 side and on the other end on the end surface of the cylinder 56 on the valve portion side. The nozzle needle 60 configured as described above is reciprocally displaced linearly in the axial direction of the cylinder 56 with respect to the cylinder 56 in accordance with the pressure of the fuel in the pressure control chamber 53 received by the valve pressure receiving surface 61, thereby the seat portion 65. Is seated on and separated from the valve seat portion 45, and the valve portion 50 is opened and closed.

  The floating plate 70 is a disk-shaped member made of a metal material, and includes a pressing surface 73, a pressing pressure receiving surface 77, a plate locking portion 78, an outer peripheral wall surface 74, and a restriction hole 71. The floating plate 70 is disposed coaxially with the cylinder 56 and is disposed in the pressure control chamber 53 so as to be reciprocally displaceable. The direction of the displacement axis of the floating plate 70 that is reciprocally displaced is along the direction of the displacement axis of the nozzle needle 60. Of the both end surfaces of the floating plate 70 in the displacement axis direction, the end surface facing the opening wall surface 90 in the displacement axis direction forms a pressing surface 73. The pressing surface 73 comes into contact with the opening wall surface 90 by the reciprocating displacement of the floating plate 70. An end surface of the floating plate 70 that is opposite to the pressing surface 73 in the displacement axis direction forms a pressing pressure receiving surface 77 that faces the valve pressure receiving surface 61 in the displacement axis direction. The pressure receiving surface 77 receives a force in the direction toward the opening wall surface 90 by the fuel in the pressure control chamber 53. A plate locking portion 78 is formed on the outer edge of the pressure receiving surface 77 to face the plate stopper portion 58a of the cylinder 56 in the displacement axis direction. The plate locking portion 78 is locked to the plate stopper portion 58 a, thereby restricting the displacement of the floating plate 70 in the direction approaching the nozzle needle 60.

  The outer peripheral wall surface 74 that continues between the both end faces is located around the displacement axis of the floating plate 70 and is along the displacement axis direction of the plate 70. The outer peripheral wall surface 74 faces the control wall surface portion 57 in a direction orthogonal to the displacement axis. In a state where the floating plate 70 is coaxially positioned with respect to the cylinder 56, the outer peripheral wall surface 74 forms a gap through which fuel can flow with the control wall surface portion 57. Through the gap between the outer peripheral wall surface 74 and the control wall surface portion 57, the fuel that has flowed into the space of the pressure control chamber 53 on the opening wall surface 90 side with respect to the floating plate 70 is separated from the plate 70 on the valve pressure receiving surface 61 side. It circulates in the space of the pressure control chamber 53.

  The restriction hole 71 extends from the radial center of the pressure receiving surface 77 of the floating plate 70 toward the outlet 54a. The extending direction of the restriction hole 71 is along the displacement axis direction of the floating plate 70. The restriction hole 71 has one end opened at the central portion in the radial direction of the pressing surface 73 facing the outflow port 54a. The restriction hole 71 communicates the pressure control chamber 53 and the outlet 54a with the pressing surface 73 of the floating plate 70 in contact with the opening wall surface 90, and the fuel from the pressure control chamber 53 to the outlet 54a. Limit circulation.

  The restriction hole 71 includes a throttle part 71 a and a concave part 72. The restricting portion 71 a defines the minimum flow passage area in the restriction hole 71 and defines the amount of fuel flowing through the restriction hole 71. The narrowed portion 71 a is closer to the end surface that forms the pressing surface 73 than to form the pressing pressure receiving surface 77 of both end surfaces of the floating plate 70 in the axial direction. The recess 72 is a cylindrical hole located coaxially with the floating plate 70 and is recessed from the pressure receiving surface 77 in a direction away from the valve pressure receiving surface 61 to partially enlarge the flow path area of the limiting hole 71. . Due to the recess 72, the opening of the restriction hole 71 in the pressure receiving surface 77 is enlarged.

(Characteristic part)
Next, the characteristic part of the fuel injection device 100 will be described in more detail based on FIG. 4 and FIG.

  The floating plate 70 is formed with an axial groove 79a and a radial groove 79b. Four axial grooves 79 a are formed on the inner peripheral wall around the displacement axis in the recess 72 at equal intervals in the circumferential direction of the recess 72. Each axial groove 79a extends along the displacement axis direction. The radial groove 79 b extends from the outer edge of the pressure receiving surface 77 toward the recess 72 on the pressure receiving surface 77. Four radial grooves 79b are formed at equal intervals in the circumferential direction of the recess 72, like the axial grooves 79a. In addition, since the axial groove 79a is continuous with the radial groove 79b, the fuel can easily flow from the inside of the radial groove 79b to the inside of the axial groove 79a.

  Here, an operation obtained by the recess 72 formed in the floating plate 70 partially expanding the flow path area of the restriction hole 71 will be described. The flow rate per unit time that flows through the throttle portion 71a in the restriction hole 71 is given by π * r ^ 4 * P / (8 * μ * L). In this equation, r is the radius of the throttle 71a, P is the fuel pressure, μ is the viscosity coefficient of the fuel, and L is the flow path length of the throttle 71a. Among these, the correlation between the viscosity coefficient μ of fuel and temperature is shown in FIG. In FIG. 5, the solid line indicates the characteristics of JIS No. 2 diesel oil, the broken line indicates the special No. 3 diesel oil, and the alternate long and short dash line indicates the characteristics of kerosene. Thus, the viscosity coefficient μ of the fuel increases as the temperature decreases. Therefore, the flow rate per unit time flowing through the throttle portion 71a decreases depending on the decrease in the temperature of the fuel. And according to the formula mentioned above, the change depending on the temperature of the flow rate becomes more prominent as the flow path length L of the throttle part 71a becomes longer. Therefore, by forming the recess 72, the flow path length L of the throttle portion 71 a is set to the length from the bottom 72 a of the recess 72 to the pressing surface 73, so that the temperature of the fuel flow rate flowing through the restriction hole 71 is increased. The dependent variation is suppressed.

  As shown in FIG. 4, the nozzle needle 60 is formed with a convex portion 62, an axial groove 69a, and a radial groove 69b. The convex portion 62 is a columnar protrusion that protrudes from the valve pressure receiving surface 61 toward the pressing pressure receiving surface 77 along the displacement axis of the nozzle needle 60. The convex portion 62 is positioned coaxially with the nozzle needle 60 and the concave portion 72 facing in the displacement axis direction. The convex portion 62 may be formed integrally with the nozzle needle 60, for example, or a separate cylindrical member may be held on the pressure receiving surface 61 by welding or screw fastening. In addition, the outer diameter of the convex portion 62 corresponds to the inner diameter of the concave portion 72 and is smaller than the inner diameter. Four axial grooves 69 a are formed on the outer peripheral wall around the displacement axis in the convex portion 62 at equal intervals in the circumferential direction of the convex portion 62. Each axial groove 69a extends along the displacement axis direction. In the valve pressure receiving surface 61, the radial groove 69 b extends from the outer edge of the valve pressure receiving surface 61 toward the proximal end portion in the protruding direction of the convex portion 62. Four radial grooves 69b are formed at equal intervals in the circumferential direction of the convex portion 62, like the axial grooves 69a. In addition, since the axial groove 69a is continuous with the radial groove 69b, fuel can easily flow from the inside of the radial groove 69b to the inside of the axial groove 69a.

  The operation of the fuel injection device 100 configured as described above to open and close the valve unit 50 to inject fuel will be described based on FIG. 4 and with reference to FIG.

  Before the outlet 54a and the return flow path 14f (see FIG. 1) communicate with each other by the operation of the pressure control valve 80, the floating plate 70 has the plate locking portion 78 seated on the plate stopper portion 58a. From this state, when the outlet 54 a communicates with the return flow path 14 f by the operation of the pressure control valve 80, the fuel flows out from the pressure control chamber 53 via the outflow path 54. As a result, the floating plate 70 is sucked toward the opening wall surface 90 due to the reduced pressure in the vicinity of the outlet 54a, and is displaced in a direction in which the plate locking portion 78 is separated from the plate stopper portion 58a.

  The floating plate 70 having the pressing surface 73 in contact with the opening wall surface 90 by the displacement presses the opening wall surface 90 with the pressing surface 73, thereby connecting the inlet 52 a and the pressure control chamber 53 that open to the opening wall surface 90. Shut off (FIG. 4 (a)). At this time, the nozzle needle 60 and the floating plate 70 are most separated from each other. In the first embodiment, in a state where the nozzle needle 60 and the floating plate 70 are farthest from each other, the convex portion 62 separates the tip portion 62 a in the projecting direction from the concave portion 72, and between the concave portion 72. A fuel flow path 92 capable of fuel flow is formed. In a state in which the nozzle needle 60 and the floating plate 70 are farthest from each other, the minimum flow area of the fuel flow path 92 is made larger than the flow area of the throttle portion 71a.

  In the pressure control chamber 53 where the inflow of fuel from the inflow port 52a is blocked, the fuel located between the pressure receiving surface 77 and the valve pressure receiving surface 61 flows through the fuel flow path 92 and the restriction hole 71 and flows. Reach the exit 54a. In the first embodiment, since the minimum flow path area of the fuel flow path 92 is larger than the flow path area of the throttle portion 71a, the fuel has a flow rate per unit time discharged from the pressure control chamber 53, The fuel channel 92 is not limited. And the fuel which reached the outflow port 54a is discharged | emitted by the return flow path 14f (refer FIG. 1). Thereby, the fuel pressure in the pressure control chamber 53 falls.

  When the discharge of fuel from the pressure control chamber 53 is continued, the fuel pressure in the pressure control chamber 53 decreases to a predetermined pressure. When the pressure in the pressure control chamber 53 falls below the predetermined pressure, the nozzle needle 60 is pushed up to the pressure control chamber 53 side, the seat portion 65 is separated from the valve seat portion 45, and the valve portion 50 is opened. Start. Due to the displacement of the nozzle needle 60 toward the floating plate 70, the convex portion 62 of the nozzle needle 60 is accommodated in the concave portion 72 of the floating plate 70. In addition, the fuel located between the pressure receiving surface 77 and the valve pressure receiving surface 61 flows between the concave portion 72 and the convex portion 62 and flows through the restriction hole 71. Thereafter, the displacement of the nozzle needle 60 toward the pressure control chamber 53 is regulated by the contact of the needle locking portion 68 with the needle stopper portion 58b. Thereby, the opening degree of the valve part 50 becomes the maximum.

  In a state where the displacement of the nozzle needle 60 is restricted by the needle stopper portion 58 b, the tip end portion 62 a of the convex portion 62 is separated from the bottom portion 72 a of the concave portion 72. In addition, the outer peripheral wall of the convex portion 62 and the inner peripheral wall of the concave portion 72 are in a state of being separated from each other. As described above, the fuel flow path 92 formed between the concave portion 72 and the convex portion 62 maintains a state in which fuel can flow. As a result, the fuel in the pressure control chamber 53 continues to be discharged via the fuel flow path 92. In addition, since the fuel can flow through each of the radial groove 79b and the axial groove 79a, or the radial groove 69b and the axial groove 69a, the flow to the restriction hole 71 is hardly hindered.

  When the outlet 54a and the return flow path 14f (see FIG. 1) are blocked by closing the pressure control valve 80, the floating plate 70 is pushed toward the valve pressure receiving surface 61 by the fuel flowing in from the inlet 52a. And start the displacement. Then, the floating plate 70 seats the plate locking portion 78 on the plate stopper portion 58a again (FIG. 4B). At this time, the nozzle needle 60 and the floating plate 70 are in a state of being closest to each other. Even in this state, the tip end portion 62 a of the convex portion 62 is separated from the bottom portion 72 a of the concave portion 72. In addition, the minimum flow path area of the fuel flow path 92 is maintained larger than the flow path area of the throttle portion 71a.

  The inflow port 52 a is opened to the pressure control chamber 53 by the displacement of the floating plate 70 toward the nozzle needle 60. The fuel that has flowed into the pressure control chamber 53 from the inflow port 52a passes through the clearance between the outer peripheral wall surface 74 of the floating plate 70 and the control wall surface portion 57 of the cylinder 56, the restriction hole 71, and the fuel flow path 92. The pressure in the space of the pressure control chamber 53 on the valve pressure receiving surface 61 side with respect to the plate 70 is increased. Then, the nozzle needle 60 is pushed down to the valve portion 50 side, and the seat portion 65 is seated on the valve seat portion 45, thereby closing the valve portion 50.

  In the first embodiment described above, the concave portion 72 is formed in the floating plate 70, but an increase in the volume of the pressure control chamber 53 due to the formation is suppressed by forming the convex portion 62. In addition, the convex portion 62 is located in the concave portion 72 with the nozzle needle 60 and the floating plate 70 being closest to each other. Under this state, the tip end portion 62 a of the convex portion 62 is separated from the bottom portion 72 a of the concave portion 72. Thus, the convex part 62 of the nozzle needle 60 does not collide with the pressure receiving surface 77 due to the relative displacement of the nozzle needle 60 and the floating plate 70. Therefore, an increase in the volume of the pressure control chamber 53 is suppressed while allowing reliable operation of the nozzle needle 60 and the floating plate 70.

  The amount of fuel discharged from the pressure control chamber 53 required to start the reciprocating displacement of the nozzle needle 60 is kept small by suppressing the increase in the volume of the pressure control chamber 53 as described above. obtain. Therefore, even if the flow rate of the fuel flowing through the restriction hole 71 varies depending on the temperature of the fuel, since the amount of fuel to be discharged is small, the variation in time required until the displacement of the nozzle needle 60 is suppressed is suppressed. Can be done.

  As described above, coupled with the effect of suppressing the variation depending on the temperature of the fuel flow rate flowing through the restriction hole 71 by the recess 72, the fuel temperature in the time from when the floating plate 70 presses the opening wall surface 90 until the start of displacement of the nozzle needle 60 is obtained. Dependent fluctuations are reliably suppressed. Therefore, the fuel injection device 100 having excellent temperature characteristics is realized.

  In addition, in the first embodiment, even if the nozzle needle 60 and the floating plate 70 are displaced relative to each other, the minimum flow path area of the fuel flow path 92 is maintained larger than the flow path area of the throttle portion 71a. Therefore, the flow rate of the fuel discharged from the pressure control chamber 53 is not easily limited by the fuel flow path 92. In addition, the displacement of the nozzle needle 60 and the floating plate 70 in the direction approaching each other is restricted by the corresponding one of the plate stopper portion 58a and the needle stopper portion 58b. As described above, the flow passage area of the fuel flow passage 92 can be reliably ensured in the state where the floating plate 70 and the nozzle needle 60 are closest to each other. As described above, the situation where the minimum flow path area of the fuel flow path 92 is smaller than the flow path area of the throttle portion 71a can be reliably avoided by appropriate arrangement of the plate stopper portion 58a and the needle stopper portion 58b. As described above, it is possible to avoid a situation in which the temperature-dependent fluctuation of the flow rate passing through the fuel flow path 92 fluctuates the time required until the nozzle needle 60 starts to be displaced.

  In the first embodiment, when the floating plate 70 and the nozzle needle 60 are relatively displaced in the direction in which they are close to each other, the distance between the pressure receiving surface 77 and the valve pressure receiving surface 61 becomes very small. Therefore, the flow rate of the fuel discharged from the pressure control chamber 53 may be limited between the pressure receiving surface 77 and the valve pressure receiving surface 61. Therefore, by forming the radial grooves 79b and 69b in the pressure receiving surface 77 and the valve pressure receiving surface 61, the fuel can be discharged in the radial direction even when the space between the pressure receiving surface 77 and the valve pressure receiving surface 61 is very small. The inside of the grooves 79b and 69b can be circulated. Therefore, the fuel can reach the restriction hole 71 via the space between the concave portion 72 and the convex portion 62 without restricting the flow between the pressure pressure receiving surface 77 and the valve pressure receiving surface 61. As described above, it is possible to avoid a situation in which a change due to temperature in the flow rate flowing between the pressure receiving surface 77 and the valve pressure receiving surface 61 changes the time required for starting the displacement of the valve member.

  Further, when the fuel flow to the restriction hole 71 is restricted between the recess 72 and the projection 62, the time required to start the displacement of the nozzle needle 60 is the amount of fuel flowing between the recess 72 and the projection 62. It varies depending on the temperature. Therefore, as in the first embodiment, by providing the axial grooves 79a and 69a, the fuel located between the pressure receiving surface 77 and the valve pressure receiving surface 61 is allowed to flow inside the axial grooves 79a and 69a. Can be distributed. Therefore, the fuel can smoothly flow between the concave portion 72 and the convex portion 62 and reach the restriction hole 71. Therefore, the fuel flows smoothly between the concave portion 72 and the convex portion 62. In addition, the corresponding one of the radial grooves 79b and 69b is made continuous with the axial grooves 79a and 69a that ensure the fuel flow between the recess 72 and the protrusion 62, respectively. The fuel flowing through the radial grooves 79b and 69b is supplied into the axial grooves 79a and 69a. Thus, the action of each axial groove 79a, 69a that allows the fuel to flow smoothly between the recess 72 and the protrusion 62 is enhanced by making the radial grooves 79b, 69b continuous. As described above, it is possible to reliably avoid a situation in which the fluctuation caused by the temperature of the flow rate between the concave portion 72 and the convex portion 62 fluctuates the time required until the nozzle needle 60 starts to be displaced.

  As described above, the temperature characteristic of the fuel injection device 100 can be further improved by suppressing the fluctuation depending on the temperature of the time required from the opening of the pressure control valve 80 to the start of the displacement of the nozzle needle 60. It becomes.

  In the first embodiment, the plate stopper portion 58a is described in the “press restricting portion” described in the claims, the needle stopper portion 58b is described in the “valve restricting portion” in the claims, and the nozzle needle 60 is described in the claims. In the “valve member”, the axial groove 69 a is formed in the “convex axial groove” and the radial groove 69 b is formed in the “convex radial groove”. In the "pressing member" described in the claims, the axial groove 79a in the "axial groove in the recess" in the claim, and the radial groove 79b in the "radial groove in the recess" in the claim, Each corresponds.

(Second embodiment)
As shown in FIG. 6, the second embodiment of the present invention is a modification of the first embodiment. The fuel injection device 200 of the second embodiment includes a floating plate 270 and a nozzle needle 260 corresponding to the floating plate 70 and the nozzle needle 60 of the first embodiment. Hereinafter, the configuration of the fuel injection device 200 according to the second embodiment will be described in detail with reference to FIG.

  The floating plate 270 is formed with a recess 272 that enlarges the flow path area of the restriction hole 271 on the pressing pressure receiving surface 277 side. The recess 272 is a cylindrical hole located coaxially with the floating plate 270. In the floating plate 270, configurations corresponding to the axial groove 79 a and the radial groove 79 b of the first embodiment are omitted from the inner peripheral wall of the recess 272 and the pressure receiving surface 277.

  The nozzle needle 260 is formed with a convex portion 262 that protrudes from the center of the valve pressure receiving surface 261 toward the pressing pressure receiving surface 277. The convex portion 262 is a columnar protrusion that is positioned coaxially with the concave portion 272 facing the nozzle needle 260 and the displacement axis direction. The outer diameter of the convex portion 262 is smaller than the inner diameter of the concave portion 272. From the outer peripheral wall of the convex portion 262 and the valve pressure receiving surface 261, configurations corresponding to the axial groove 69a and the radial groove 69b of the first embodiment are omitted.

  Even in the fuel injection device 200 according to the second embodiment described above, an increase in the volume of the pressure control chamber 53 due to the formation of the concave portion 272 is suppressed by forming the convex portion 262. In addition, since the collision of the convex portion 262 with the floating plate 270 is avoided, the nozzle needle 260 and the floating plate 270 can operate reliably. As described above, coupled with the effect of suppressing the temperature-dependent fluctuation of the fuel flow rate flowing through the restriction hole 271 by the recess 272, the fuel temperature in the time from when the floating plate 270 presses the opening wall surface 90 until the start of displacement of the nozzle needle 260 is obtained. Dependent fluctuations are reliably suppressed. Therefore, the fuel injection device 200 having excellent temperature characteristics is realized.

  In addition, in the second embodiment, in the state where the floating plate 270 and the nozzle needle 260 are relatively displaced so as to be farthest from each other (FIG. 6A), the convex portion 262 is detached from the concave portion 272. Under this state, the minimum flow area of the fuel flow path 292 between the convex part 262 and the concave part 272 is surely larger than the minimum flow area of the restriction hole 271 by the separation of the convex part 262 from the concave part 272. Become. Therefore, the flow rate per unit time discharged from the pressure control chamber 53 is not limited by the fuel flow path 292.

  In the second embodiment, when the floating plate 270 and the nozzle needle 260 are considerably displaced so as to be closest to each other (FIG. 6B), the gap between the outer peripheral wall of the convex portion 262 and the inner peripheral wall of the concave portion 272 is small. A fuel flow path 292 is formed in the bottom. In this state, by making the difference between the outer diameter of the convex portion 262 and the inner diameter of the concave portion 272 appropriate, the minimum flow area of the fuel flow path 292 can be reduced without restricting the axial hole. The minimum flow area can be made larger.

  According to the above, since the effect of suppressing the temperature-dependent fluctuation of the time required from the opening of the pressure control valve 80 (see FIG. 2) to the start of the displacement of the nozzle needle 260 is reliably exhibited, the fuel injection device 200 The improvement of the temperature characteristic of this is further ensured.

  In the second embodiment, the nozzle needle 260 corresponds to the “valve member” recited in the claims, and the floating plate 270 corresponds to the “pressing member” recited in the claims.

(Third embodiment)
As shown in FIG. 7, the third embodiment of the present invention is a modification of the second embodiment. The fuel injection device 300 of the third embodiment includes a nozzle needle 360 corresponding to the nozzle needle 260 of the second embodiment. Hereinafter, the configuration of the fuel injection device 300 according to the third embodiment will be described in detail with reference to FIG.

  The length of the protruding portion 362 of the nozzle needle 360 in the protruding direction is longer than that of the protruding portion 262 of the second embodiment. Therefore, in a state where the floating plate 270 and the nozzle needle 360 are farthest from each other, the distal end portion 362a of the convex portion 362 is located in the concave portion 272 (FIG. 7A). Under this state, the flow area of the fuel flow path 392 formed between the convex portion 362 and the concave portion 272 is determined by the difference between the outer diameter of the convex portion 362 and the inner diameter of the concave portion 272. As described above, even if the tip 362 a of the convex portion 362 is always located in the concave portion 272, the difference between the outer diameter of the convex portion 362 and the inner diameter of the concave portion 272 is made appropriate, so that the fuel flow path 392 The minimum channel area can be made larger than the minimum channel area of the restriction hole 271.

  Further, in the state where the nozzle needle 360 and the floating plate 270 are closest to each other (FIG. 7B), the tip portion 362 a of the convex portion 362 is separated from the bottom portion 272 a of the concave portion 272. In this state, the minimum flow area of the fuel flow path 392 formed between the tip portion 362a and the bottom portion 272a is larger than the minimum flow area of the restriction hole 271.

  As described above, even if the length of the convex portion 362 is extended, the fuel flow path 392 can have a flow path area regardless of the positions of the displacement of the nozzle needle 360 and the floating plate 270. Therefore, a situation where the flow rate per unit time discharged from the pressure control chamber 53 is limited by the fuel flow path 392 can be avoided.

  In addition, by increasing the length of the protruding portion 362 in the protruding direction, the volume of the protruding portion 362 increases. Therefore, an increase in the volume of the pressure control chamber 53 due to the formation of the recess 272 is reliably suppressed. As described above, the fluctuation depending on the fuel temperature in the time until the start of displacement of the nozzle needle 360 is further reliably suppressed. Therefore, the temperature characteristics of the fuel injection device 300 can be improved.

  In the third embodiment, the nozzle needle 360 corresponds to a “valve member” recited in the claims.

(Fourth embodiment)
As shown in FIG. 8, the fourth embodiment of the present invention is a modification of the third embodiment. The fuel injection device 400 of the fourth embodiment includes a floating plate 470 and a nozzle needle 460 corresponding to the floating plate 270 and the nozzle needle 360 of the third embodiment. In addition, the fuel injection device 400 includes a plate spring 476 between the floating plate 470 and the nozzle needle 460. Hereinafter, the configuration of the fuel injection device 400 according to the fourth embodiment will be described in detail with reference to FIG.

  The floating plate 470 is formed with a recess 472 that enlarges the flow path area of the restriction hole 471 on the pressing pressure receiving surface 477 side. The recess 472 is a cylindrical hole located coaxially with the floating plate 470. In addition, the floating plate 470 is formed with a biasing recess 477a which is a cylindrical hole having an inner diameter larger than that of the recess 472 and a shallow depth in the displacement axis direction. The urging recess 477a is formed by recessing the periphery of the recess 472 in the pressing pressure receiving surface 477 in a direction away from the valve pressure receiving surface 461 opposed in the displacement axis direction. The urging recess 477a is positioned coaxially with the recess 472.

  The nozzle needle 460 is formed with a convex portion 462 that protrudes from the center of the valve pressure receiving surface 461 toward the pressure receiving surface 477. The convex portion 462 is a columnar protrusion positioned coaxially with the concave portion 472 facing the nozzle needle 460 and the displacement axis direction. The outer diameter of the convex portion 462 is smaller than the inner diameter of the concave portion 472. In addition, the nozzle needle 460 is formed with a cylindrical urging convex portion 461a having an outer diameter larger than that of the convex portion 462 and short in the displacement axis direction. The biasing convex portion 461a is formed by projecting the periphery of the convex portion 462 in the valve pressure receiving surface 461 in a direction close to the pressing pressure receiving surface 477 facing the displacement axis direction. The biasing convex portion 461a is positioned coaxially with the convex portion 462 and the biasing convex portion 461a facing each other in the displacement axial direction.

  The plate spring 476 is a coil spring in which a metal wire is wound around. The plate spring 476 is disposed between the floating plate 470 and the nozzle needle 460 while being compressed in the axial direction, and biases the floating plate 470 toward the opening wall surface 90 with respect to the nozzle needle 460. The end of the plate spring 476 on the pressing pressure receiving surface 477 side in the displacement axis direction is fitted into the inner peripheral wall of the biasing recess 477a and is seated on the bottom of the biasing recess 477a. Further, the end of the plate spring 476 on the valve pressure receiving surface 461 side in the displacement axis direction is fitted on the outer peripheral wall of the biasing convex portion 461a, and the valve pressure receiving surface 461 located on the outer peripheral side of the biasing convex portion 461a. Sitting.

  In the fourth embodiment described above, the tip end portion 462a of the convex portion 462 is located in the concave portion 472 in a state where the floating plate 470 and the nozzle needle 460 are farthest from each other (FIG. 8A). In this state, the minimum flow area of the fuel flow path 492 formed between the convex portion 462 and the concave portion 472, which is determined by the difference between the outer diameter of the convex portion 462 and the inner diameter of the concave portion 472, is the fourth embodiment. Also in the form, it is made larger than the minimum flow path area of the restriction hole 471.

  On the other hand, in a state where the nozzle needle 460 and the floating plate 470 are closest to each other (FIG. 8B), the tip end portion 462 a of the convex portion 462 is separated from the bottom portion 472 a of the concave portion 472. In this state, the minimum flow area of the fuel flow path 492 formed between the front end 462a and the bottom 472a is also made larger than the minimum flow area of the restriction hole 471.

  Here, even when the nozzle needle 460 and the floating plate 470 are in the closest state, the fuel must be able to smoothly flow between the inner peripheral side and the outer peripheral side of the plate spring 476. Therefore, even if the plate spring 476 is most compressed in the axial direction between the pressure receiving surface 477 and the valve pressure receiving surface 461, the plate spring 476 can maintain a gap through which fuel can flow between the adjacent wires in the axial direction. ing.

In the fuel injection device 400 having the plate spring 476 as in the fourth embodiment described so far, the position of the plate spring 476 may be shifted along the pressure receiving surface 477 or the valve pressure receiving surface 461. When the plate spring 476 is displaced, the displacement axis direction of the floating plate 470 along the displacement axis direction of the nozzle needle 460 may be inclined with respect to the displacement axis direction of the nozzle needle 460. The inclination of the displacement axis of the floating plate 470 causes the fuel flow path 492 that should be formed between the concave portion 472 and the convex portion 462 to disappear, and the factor that prevents the passage of fuel between the concave portion 472 and the convex portion 462. Can be. Therefore, the end of the pressure receiving surface 477 side is fitted into the biasing recess 477a, and the end of the valve pressure receiving surface 461 is fitted into the valve receiving biasing projection 461a, so that the plate spring 476 is not displaced. Can be suppressed. Therefore, the fuel flow path 492 through which fuel can pass can be reliably maintained between the concave portion 472 and the convex portion 462. Therefore, the temperature characteristics in the fuel injection device 400 including the plate spring 476 can be reliably improved by forming the urging concave portion 477a and the urging convex portion 461a that suppress the displacement of the plate spring 476.

  In the fourth embodiment, the nozzle needle 460 is the “valve member” according to the claims, the floating plate 470 is the “pressing member” according to the claims, and the plate spring 476 is the “bias” according to the claims. Corresponds to “members”.

(Other embodiments)
As mentioned above, although several embodiment by this invention was described, this invention is limited to these embodiment and is not interpreted and can be applied to various embodiment in the range which does not deviate from the summary.

  In the embodiment described above, the plate stopper portion 58a and the needle stopper portion 58b that restrict the displacement of the nozzle needle and the floating plate and prevent mutual collision are formed in the cylinder 56 of the control body 40. However, for example, in the form in which the plate spring is disposed between the slewing needle and the floating plate as in the fourth embodiment, since the plate spring can avoid mutual collision, the configuration corresponding to the plate stopper portion and the needle stopper portion. May be omitted.

  In the above-described embodiment, a mechanism for driving the mover 35 by the electromagnetic force of the solenoid 31 is used as the drive unit that opens and closes the pressure control valve 80 that controls the pressure of the fuel in the pressure control chamber 53. However, as long as it is a drive unit that can move according to a control signal from the engine control device 17 and can open and close the pressure control valve 80, a form using, for example, a piezo element other than a form using a solenoid may be used.

  In the above, the example which applied this invention to the fuel-injection apparatus used for the diesel engine 20 which injects a fuel directly to the combustion chamber 22 was demonstrated. However, the present invention is not limited to the diesel engine 20 and may be applied to a fuel injection device used for an internal combustion engine such as an Otto cycle engine. In addition, the fuel injected by the fuel injection device is not limited to light oil but may be gasoline, liquefied petroleum gas, or the like. Furthermore, the present invention may be applied to a fuel injection device that injects fuel toward a combustion chamber of an engine that burns fuel such as an external combustion engine.

DESCRIPTION OF SYMBOLS 10 Fuel supply system, 11 Fuel tank, 12 Feed pump, 12a, 13a, 14e Fuel piping, 13 High pressure fuel pump, 14 Common rail, 14a Branch part, 14b Common rail sensor, 14c Pressure regulator, 14d Supply flow path, 14f Return flow path , 17 Engine control device, 20 Diesel engine, 21 Head member, 22 Combustion chamber, 30 Control valve drive unit, 31 Solenoid, 32 Terminal, 33 Valve seat member, 34 Spring, 35 Mover, 36 Stator, 40 Control body, 41 Nozzle body, 43 Nozzle needle housing part, 44 Injection hole, 45 Valve seat part, 46 Valve body (valve body member), 47a Control valve seat part, 48 Holder, 48a, 48b Vertical hole, 48c Socket part, 49 Retaining Nut, 49a Step , 50 Valve part, 52 Inflow path, 52a Inlet, 53 Pressure control chamber, 54 Outlet path, 54a Outlet, 56 Cylinder, 57 Control wall surface part, 57a Concave part, 58a Plate stopper part (press restriction part), 58b Needle stopper Part (valve regulating part), 59 cylinder sliding part, 60, 260, 360, 460 nozzle needle (valve member), 61, 261, 461 valve pressure receiving face, 461a biasing convex part, 62, 262, 362, 462 convex Part, 62a, 362a, 462a tip part, 63 needle sliding part, 65 seat part, 66 return spring, 67 collar member, 68 needle locking part, 69a (protruding part) axial groove, 69b (convex part) Radial groove, 70,270,470 floating plate (pressing member), 70a outer wall surface, 71,271,471 restriction hole, 1a throttle part, 72,272,472 concave part, 72a, 272a, 472a bottom part, 73 pressing surface, 73a end face, 74 outer peripheral wall surface, 476 plate spring, 77,277,477 pressure receiving surface, 477a biasing concave part, 78 plate engagement Stop, 79a Axial groove (in the recess), 79b Radial groove in the recess, 80 Pressure control valve, 90 Open wall, 92, 292, 392, 492 Fuel flow path, 94 Inflow recess, 97 Outflow recess, 100 , 200, 300, 400 Fuel injection device

Claims (12)

A fuel injection device that opens and closes a valve unit that controls injection from a nozzle hole of supply fuel supplied from a supply channel, and discharges part of the supplied fuel to a return channel in accordance with the control,
The fuel that has flowed through the supply flow path flows in from the inlet, the pressure control chamber that discharges the fuel to the return path through the outlet, and the pressure control chamber exposed to the inlet and the outlet A control body having an open wall surface that is open,
A pressure control valve that switches between communication and blocking between the outlet and the return flow path, and controls the pressure of the fuel in the pressure control chamber;
A valve member that opens and closes the valve portion by reciprocating displacement according to the fuel pressure received by the valve pressure receiving surface, the valve pressure receiving surface exposed to the pressure control chamber;
The pressure control chamber is disposed so as to be capable of reciprocating displacement along the displacement axis direction of the valve member, and is a pressure receiving surface facing the valve pressure receiving surface in the displacement axis direction, extending from the pressure receiving surface toward the outlet. And when the outlet and the return channel communicate with each other by the pressure control valve, the opening wall surface is pressed so as to block the communication between the inlet and the pressure control chamber, The amount of fuel flow from the pressure control chamber to the outlet is limited by a hole, and the inlet is opened to the pressure control chamber when the outlet and the return flow path are blocked by the pressure control valve. A pressing member that is displaced so that at least a part thereof is separated from the opening wall surface,
The pressing member is recessed from the pressure receiving surface in a direction away from the valve pressure receiving surface, and has a recess that partially enlarges the flow path area of the restriction hole,
The valve member protrudes from the valve pressure receiving surface toward the pressure pressure receiving surface, and the valve member and the pressing member are located in the closest proximity to each other, and are located in the recess and have a tip in the protruding direction of the recess. A fuel injection device having a convex portion spaced from a bottom portion.   The minimum flow area of the fuel flow path formed between the concave portion and the convex portion by relative displacement of the pressing member and the valve member in the direction of approaching each other is the minimum flow path of the restriction hole. The fuel injection device according to claim 1, wherein the fuel injection device is larger than an area.   The control body includes a pressure restricting portion that restricts displacement of the pressing member in a direction approaching the valve member, and a valve restricting portion that restricts displacement of the valve member in a direction approaching the pressing member. The fuel injection device according to claim 2, wherein the fuel injection device is provided.   The fuel injection device according to any one of claims 1 to 3, wherein an axial groove of the recess along the displacement axis direction is formed in an inner peripheral wall around the displacement axis in the recess. .   The fuel according to any one of claims 1 to 4, wherein an axial groove of the convex portion along the displacement axis direction is formed in an outer peripheral wall around the displacement axis in the convex portion. Injection device.   The fuel according to any one of claims 1 to 5, wherein a radial groove of a recess extending from the outer edge of the pressure receiving surface to the recess is formed on the pressure receiving surface. Injection device. In the recess, an inner circumferential wall around the displacement axis is formed with an axial groove of the recess along the displacement axis direction.
The fuel injection device according to claim 6, wherein the axial groove of the recess is continuous with the radial groove of the recess.   The fuel injection device according to claim 1, wherein a radial groove of a convex portion extending from the outer edge of the valve pressure receiving surface toward the convex portion is formed on the valve pressure receiving surface. An axial groove of the convex portion along the displacement axis direction is formed on the outer peripheral wall around the displacement axis in the convex portion,
The fuel injection device according to claim 8, wherein the axial groove of the convex portion is continuous with the radial groove of the convex portion.   The fuel injection according to any one of claims 1 to 9, wherein the convex portion is detached from the concave portion when the pressing member and the valve member are relatively displaced in a direction away from each other. apparatus.   The fuel injection according to any one of claims 1 to 9, wherein the tip portion of the convex portion is located in the concave portion in a state where the pressing member and the valve member are most separated from each other. apparatus. The pressing pressure receiving surface forms a biasing recess by recessing the periphery of the recess in a direction away from the valve pressure receiving surface,
The valve pressure receiving surface forms a biasing convex portion by projecting around the convex portion in a direction close to the pressing pressure receiving surface,
A biasing member that biases the pressing member toward the opening wall surface with respect to the valve member;
The biasing member has an end on the pressing pressure receiving surface side in the displacement axis direction fitted in the biasing recess, and an end on the valve pressure receiving surface side in the displacement axis direction is outside the biasing projection. The fuel injection device according to claim 1, wherein the fuel injection device is fitted.

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