Fuel injection device

Abstract

To provide a fuel injection device capable of suppressing adhesion of fuel to the surface of a tip portion and improving combustion stability.SOLUTION: A fuel injection device includes a nozzle body, an injection hole forming member 12, and a valve element 20. The injection hole forming member 12 has a seat part 124 having a seat surface 124a, and a suck chamber 125 formed at the tip portion of the seat part 124. The suck chamber 125 is formed with a suck chamber injection hole 18 for injecting fuel toward a spark plug. A starting end portion 127 of the suck chamber injection hole 18 is located closer to the valve element 20 side than the apex 128 of a virtual cone that is formed when the seat surface 124a is extended.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel injection device. [Background technology]

[0002]

[0003] Conventionally, internal combustion engines have been used as direct injection type internal combustion engines in which fuel is directly injected into a cylinder by a fuel injection device. As a conventional technique relating to a fuel injection device, for example, there is one described in Patent Document 1.

[0003] Patent Document 1 describes a technology related to a fuel injection device including a valve body and an injection hole forming portion in which a plurality of injection holes for injecting fuel are formed on the tip side of the valve body. Patent Document 1 also describes that the injection hole forming portion is formed with a first injection hole in which the intersection angle between the central axis of the injection hole forming portion and the first injection hole axis is θ1, and a second injection hole in which the intersection angle between the central axis of the injection hole forming portion and the second injection hole axis is θ2 which is larger than θ1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 101118 Summary of the Invention [Problem to be solved by the invention]

[0005] Furthermore, fuel during or after injection tends to adhere to the tip of the fuel injection device. However, the technology described in Patent Document 1 does not take into consideration the fuel adhering to the tip. As a result, the technology described in Patent Document 1 has a problem in that the fuel adhering to the tip turns to soot, which makes it easier for luminous flames to occur and deteriorates exhaust gas performance.

[0006] In consideration of the above problems, an object of the present invention is to provide a fuel injection device that can suppress adhesion of fuel to the surface of the tip portion and improve the stability of combustion. [Means for solving the problem]

[0007] In order to solve the above problems and achieve the object, the fuel injection device includes a nozzle body, an injection hole forming member, and a valve body. The nozzle body is installed in a cylinder of an internal combustion engine in which an ignition plug is arranged. The injection hole forming member is provided at a tip end of the nozzle body. The valve body is formed with a valve body side seat surface that comes into contact with and separates from a seat surface provided on the injection hole forming member. The injection hole forming member has a seat portion having a seat surface and a suction chamber formed at a tip end of the seat portion. The suction chamber is formed with a suction chamber injection hole for injecting fuel toward the ignition plug. The start end of the suction chamber injection hole, which is the end on the rear end side in the axial direction of the valve body, is located on the valve body side of the apex of an imaginary cone formed when the seat surface is extended. Effect of the Invention

[0008] According to the fuel injection device having the above configuration, adhesion of fuel to the surface of the tip portion can be suppressed, and the stability of combustion can be improved. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a fuel injection device according to an embodiment. [Diagram 2] 1 is a schematic diagram showing a state in which a fuel injection device according to an embodiment is mounted on an internal combustion engine; [Diagram 3] 2 is an enlarged cross-sectional view showing a tip portion of a fuel injection device according to an embodiment. FIG. [Figure 4] 1 is a front view showing a tip portion of a fuel injection device according to an embodiment; [Diagram 5] 1 is an external perspective view showing a spray injected from a fuel injection device according to an embodiment; [Figure 6]4 is an explanatory diagram showing an enlarged view of a state in which fuel is injected from a sac chamber injection hole and a seat portion injection hole in the fuel injection device according to the embodiment; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a fuel injection device will be described with reference to Figures 1 to 6. In addition, the same reference numerals are used to designate common members in each figure.

[0011] 1. Example of embodiment 1-1.Fuel injection system configuration First, the configuration of a fuel injection device according to an embodiment (hereinafter referred to as "this example") will be described with reference to FIG. FIG. 1 is an exploded perspective view showing a fuel injection device.

[0012] The fuel injection device shown in Fig. 1 is used in a four-stroke internal combustion engine that repeats four strokes: intake stroke, compression stroke, combustion (expansion) stroke, and exhaust stroke. The fuel injection device 1 is applied to a direct injection type internal combustion engine that injects fuel into each cylinder.

[0013] 1, the fuel injection device 1 includes a nozzle body 10, a valve body 20, a movable core 30, a fixed core 40, a coil 50, a housing 70, a connection portion 80, and a filter 90. The fuel injection device 1 also includes a first spring 61, a second spring 63, and an adjustment member 62.

[0014] [Nozzle body] The nozzle body 10 is formed in a cylindrical shape. A first internal space 130 is formed at the tip end, which is one end of the nozzle body 10 in the axial direction Da (hereinafter simply referred to as the "axial direction Da") along the central axis AX1. A large diameter portion 14 having an outer diameter larger than that of the tip end is formed at the rear end, which is the other end of the nozzle body 10 in the axial direction Da. A second internal space 140 is formed in this large diameter portion 14. The first internal space 130 and the second internal space 140 are communicated with each other through a communication hole 16 formed along the axial direction Da of the nozzle body 10.

[0015] The first internal space 130 is a recess recessed inward in the axial direction Da from the tip of the nozzle body 10. The injection hole-forming member 12 is attached by insertion or press-fitting into this first internal space 130. The injection hole-forming member 12 is fixed to the nozzle body 10 by welding around the entire inner periphery of the opening of the tip of the nozzle body 10. A plurality of injection holes 18, 19 for injecting fuel are formed in the injection hole-forming member 12. The detailed configurations of the injection hole-forming member 12 and the injection holes 18, 19 will be described later.

[0016] Furthermore, a plurality of (two in this example) grooves 131 are formed on the outer peripheral surface of the nozzle body 10 on the tip side. The grooves 131 are formed continuously along the circumferential direction of the outer peripheral surface of the nozzle body 10. A seal member 15 is fitted into the grooves 131. When the fuel injection device 1 is attached to a cylinder 301 (see FIG. 2) of an internal combustion engine, the seal member 15 seals the gap between the cylinder 301 and the fuel injection device 1.

[0017] The second internal space 140 is a bottomed recess that opens at the rear end side of the large diameter portion 14 and recesses toward the tip side in the axial direction Da. A movable core 30 and a part of the fixed core 40, which will be described later, are disposed in the second internal space 140. A spring accommodating portion 141 is formed in the center of the bottom of the second internal space 140, and is formed concentrically with the second internal space 140. The spring accommodating portion 141 is a cylindrical recess that recesses from the bottom to the tip of the second internal space 140. One end of the second spring 63 is accommodated in the spring accommodating portion 141.

[0018] [Valve body] A valve body 20 is disposed inside the nozzle body 10 so as to be movable along the axial direction Da. The valve body 20 is formed in a cylindrical shape. The valve body 20 has a rear end portion 21, a front end portion 23, and an intermediate portion 22 that is intermediate between the rear end portion 21 and the front end portion 23. The front end portion 23 is formed on the front end side of the valve body 20 in the axial direction Da, and the rear end portion 21 is formed on the rear end side of the valve body 20 in the axial direction Da.

[0019] The tip portion 23 is housed in an injection hole forming member 12 provided at the tip portion of the nozzle body 10. The tip portion 23 opens and closes the injection holes 18, 19 provided in the injection hole forming member 12 as the valve body 20 moves along the axial direction Da. The detailed configuration of the tip portion 23 will be described later.

[0020] The intermediate portion 22 is provided continuously from the rear end side of the tip portion 23 in the axial direction Da. The intermediate portion 22 is disposed in the communication hole 16 of the nozzle body 10. A gap G1 is formed between an outer circumferential surface 221 of the intermediate portion 22 and an inner circumferential surface of the communication hole 16. The rear end portion 21 is provided continuously from the rear end side of the intermediate portion 22 in the axial direction Da.

[0021] The rear end portion 21 is disposed in the second internal space 140 in the nozzle body 10. The rear end portion 21 is formed in a generally cylindrical shape larger than the outer diameter of the intermediate portion 22. The rear end portion 21 is inserted into a cylindrical hole of a fixed core 40, which will be described later. The rear end portion 21 is provided with a rear end sliding portion 211, a plurality of flow path forming portions 212, and an engagement portion 213.

[0022] The rear end sliding portion 211 is formed on an outer circumferential surface of the rear end portion 21. The rear end sliding portion 211 is slidably supported on an inner circumferential surface 41 of a fixed core 40, which will be described later. As a result, the valve body 20 is supported by the fixed core 40 so as to be movable along the axial direction Da.

[0023] The plurality of flow passage forming portions 212 are formed by cutting out a plurality of notches along the axial direction Da on the outer circumferential surface of the rear end portion 21. The flow passage forming portions 212 form flow passages FC through which the fuel passes between them and an inner circumferential surface 41 of a fixed core 40, which will be described later.

[0024] The engaging portion 213 is provided closer to the tip end in the axial direction Da than the flow passage forming portion 212 provided at the rear end portion 21. The engaging portion 213 protrudes radially outward from the outer circumferential surface of the rear end portion 21. This engaging portion 213 engages with a movable core 30, which will be described later, when the valve body 20 performs valve opening and closing operations.

[0025] Moreover, one end of a first spring 61 abuts against an end face on the rear end side in the axial direction Da of the rear end 21. The valve body 20 is biased by the first spring 61 toward the tip end side (valve closing side) in the axial direction Da.

[0026] The valve body 20 having the above-mentioned configuration is made of a metal material such as SUS.

[0027] [Movable core] Next, the movable core 30 will be described. The movable core 30 is disposed in the second internal space 140 of the nozzle body 10, between the rear end portion 21 of the valve body 20 and the bottom of the second internal space 140. A minute gap G3 is formed between the outer peripheral surface of the movable core 30 and the inner peripheral surface of the second internal space. Therefore, the movable core 30 is disposed in the second internal space 140 so as to be movable along the axial direction Da.

[0028] The movable core 30 is formed in a cylindrical shape. An insertion hole 31 and an eccentric through hole 32 are formed in the movable core 30. The insertion hole 31 and the eccentric through hole 32 are through holes that penetrate the movable core 30 from one end to the other end in the axial direction Da. The insertion hole 31 is formed on the central axis of the movable core 30. The middle portion 22 of the valve body 20 is inserted into the insertion hole 31.

[0029] The eccentric through hole 32 is formed at a position eccentric to the central axis of the movable core 30. The eccentric through hole 32 communicates with a flow passage FC formed by the flow passage forming portion 212 and the inner circumferential surface 41 of the fixed core 40. The eccentric through hole 32 forms the flow passage FC through which the fuel passes.

[0030] The other end of the second spring 63 abuts against the end face on the tip side in the axial direction Da of the movable core 30. Therefore, the second spring 63 is interposed between the movable core 30 and the spring accommodating portion 141 of the nozzle body 10. In addition, the fixed core 40 abuts against the end face on the rear end side of the movable core 30 in the axial direction Da.

[0031] [Fixed core] Next, the fixed core 40 is a member that attracts the movable core 30 by magnetic attraction. The fixed core 40 is formed in a substantially cylindrical shape with irregularities on the outer circumferential surface. The tip end of the fixed core 40 in the axial direction Da is press-fitted into the inside of the large diameter portion 14 of the nozzle body 10, i.e., into the second internal space 140. The nozzle body 10 and the fixed core 40 are then joined by welding. As a result, the gap between the nozzle body 10 and the fixed core 40 is sealed, and the internal space of the nozzle body 10 is sealed.

[0032] In addition, the tip of the fixed core 40 faces the rear end face in the axial direction Da of the movable core 30 disposed in the second internal space 140. The tip of the fixed core 40 facing the movable core 30 may be coated with plating such as hard chrome plating or electroless nickel plating. This can improve the durability and reliability of the tip of the fixed core 40 with which the movable core 30 collides.

[0033] Similarly, the rear end of the movable core 30 facing the fixed core 40 may be coated with plating such as hard chrome plating or electroless nickel plating. This ensures the durability and reliability of the movable core 30 even when the movable core 30 is made of relatively soft magnetic stainless steel.

[0034] The rear end side of the fixed core 40 in the axial direction Da protrudes from the second internal space 140 of the nozzle body 10 toward the rear end in the axial direction Da.

[0035] A through hole 42 is formed in the fixed core 40. The through hole 42 is formed coaxially with the central axis AX1. The through hole 42 forms a flow path FC through which fuel passes. An opening 43 communicating with the through hole 42 is formed at the rear end of the fixed core 40 in the axial direction Da. Fuel is introduced from this opening 43 toward the through hole 42. A filter 90 is inserted from the opening 43 to the through hole 42.

[0036] Furthermore, a first spring 61 and an adjustment member 62 are arranged on the tip end side of the through hole 42 in the axial direction Da. The first spring 61 is arranged closer to the tip end side of the through hole 42 than the adjustment member 62. The adjustment member 62 is press-fitted into the through hole 42 and fixed inside the fixed core 40. Also, the rear end portion 21 of the valve body 20 is inserted from the tip end of the through hole 42. The first spring 61 is interposed between the adjustment member 62 and the rear end portion 21 of the valve body 20. The first spring 61 biases the valve body 20 in the axial direction Da toward the tip end of the nozzle body 10.

[0037] Moreover, by adjusting the fixed position of the adjustment member 62 relative to the fixed core 40, the biasing force of the first spring 61 on the valve body 20 can be adjusted. This makes it possible to adjust the initial load with which the tip portion 23 of the valve body 20 presses against a seat surface 124a provided on an injection hole forming member 12 of the nozzle body 10, which will be described later.

[0038] Here, the force with which the first spring 61 urges the valve body 20 toward the tip of the nozzle body 10 is set to be greater than the force with which the second spring 63 urges the movable core 30 toward the fixed core 40.

[0039] [coil] Next, the coil 50 will be described. The coil 50 is wound around a cylindrical coil bobbin 51. The coil 50 is wound around the coil bobbin 51 and disposed so as to cover a part of the outer circumferential surface of the large diameter portion 14 of the nozzle body 10 and a part of the outer circumferential surface of the tip of the fixed core 40. The winding start and winding end ends of the coil 50 are connected to a power supply terminal 811 of a connector 81 of a connection part 80 to be described later via wiring (not shown). A housing 70 is fixed to the outer periphery of the coil 50 and the coil bobbin 51.

[0040] [housing] The housing 70 is formed in a cylindrical shape with a bottom. A through hole 71 is formed in the bottom, which is the tip end of the housing 70 in the axial direction Da. The through hole 71 is formed in the center of the bottom. The large diameter portion 14 of the nozzle body 10 is inserted into this through hole 71. The opening edge of the through hole 71 and the outer circumferential surface of the nozzle body 10 are welded, for example, over the entire circumference. In this way, the nozzle body 10 is fixed to the housing 70.

[0041] The housing 70 is disposed so as to surround the tip end side of the fixed core 40, the coil bobbin 51, and the outer periphery of the coil 50. The inner peripheral surface of the housing 70 faces the large diameter portion 14 of the nozzle body 10 and the coil 50, forming an outer peripheral yoke portion. In this manner, a trodile-shaped magnetic passage including the fixed core 40, the movable core 30, the nozzle body 10, and the housing 70 is formed around the coil 50.

[0042] [Connection] The connection part 80 is made of resin. The connection part 80 is filled between the fixed core 40, the coil 50, the coil bobbin 51, and the housing 70. The connection part 80 covers the outer peripheral surface of the fixed core 40, except for the rear end portion, on the rear end side of the housing 70 in the axial direction Da. The connection part 80 is molded to form a connector 81 having a terminal 811 for supplying power. The terminal 811 is connected to a connection terminal of a plug (not shown). This connects the fuel injection device 1 to a high-voltage power source or a battery power source. The supply of electricity to the coil 50 is controlled by an engine control unit (ECU) (not shown).

[0043] 1-2. Example of fuel injection system operation Next, an example of the operation of the fuel injection device 1 having the above-mentioned configuration will be described with reference to FIGS. FIG. 2 is a schematic diagram showing a state in which the fuel injection device 1 is mounted on an internal combustion engine.

[0044] 2, the fuel injection device 1 is installed on the wall surface of a cylinder 301 that constitutes an internal combustion engine. In the fuel injection device 1, the tip portion of a nozzle body 10, which is the tip portion that injects fuel, is disposed within a combustion chamber 310 formed by the inner wall surface of the cylinder 301 and a piston 302. In addition, the tip portion of the nozzle body 10 in the fuel injection device 1 is disposed facing an ignition plug 300.

[0045] As described above, the biasing force of the first spring 61 is set to be larger than the biasing force of the second spring 63. Therefore, when the coil 50 described below is not energized, the tip portion 23 of the valve body 20 is pressed against the seat surface 124a of the injection hole forming member 12 described below. As a result, the flow path FC leading to the injection holes 18, 19 is closed by the valve body 20, resulting in a valve-closed state.

[0046] Next, when the ECU energizes the coil 50, a magnetic flux flows in a magnetic circuit including the fixed core 40, the movable core 30, the nozzle body 10, and the housing 70. Then, a magnetic attraction force that attracts the movable core 30 is generated in the fixed core 40. When the magnetic attraction force of the fixed core 40 exceeds the biasing force of the first spring 61, i.e., the set load, the movable core 30 moves toward the fixed core 40. The movable core 30 moves until the end face facing the fixed core 40, i.e., the rear end face, collides with the front end face of the fixed core 40.

[0047] When the movable core 30 moves, the engaging portion 213 provided on the rear end portion 21 of the valve body 20 engages with the movable core 30. Therefore, the valve body 20 moves together with the movable core 30 toward the rear end side along the axial direction Da toward the fixed core 40.

[0048] As the valve element 20 moves toward the fixed core 40, the tip 23 of the valve element 20 moves away from the injection hole forming member 12. As a result, the flow path FC formed between the valve element 20 and the injection hole forming member 12 and leading to the injection hole 18 is opened, resulting in an open valve state in which the injection holes 18, 19 are open.

[0049] When the valve body 20 is in the open position (open state), fuel is introduced into the opening 43 of the fixed core 40 through the filter 90. Then, the fuel flows through the through hole 42 of the fixed core 40 toward the nozzle body 10. The fuel also passes through the adjustment member 62 and the first spring 61 arranged in the through hole 42, and flows through the flow path FC formed between the flow path forming portion 212 of the valve body 20 and the inner circumferential surface 41 of the fixed core 40. Then, the fuel flows into the second internal space 140 of the nozzle body 10 through the eccentric through hole 32 of the movable core 30.

[0050] The fuel that has flowed into the second internal space 140 passes through a gap G1 formed between the valve body 20 and the communication hole 16 of the nozzle body 10, and flows into the first internal space 130 of the nozzle body 10. The fuel then flows through a flow path FC formed between the tip end 23 of the valve body 20 and the injection hole forming member 12, and is injected into the combustion chamber 310 through the injection holes 18, 19.

[0051] Furthermore, when the ECU interrupts the energization of the coil 50, the magnetic flux flowing through the magnetic circuit including the fixed core 40, the movable core 30, the nozzle body 10, and the housing 70 disappears. Then, the magnetic attraction force of the fixed core 40 attracting the movable core 30 also disappears. Therefore, the state returns to the initial state in which the elastic force of the first spring 61 urging the valve body 20 toward the injection hole forming member 12 of the nozzle body 10 is greater than the elastic force of the second spring 63 urging the movable core 30 toward the fixed core 40.

[0052] As a result, the valve body 20 is urged by the first spring 61 toward the injection hole forming member 12 of the nozzle body 10, and moves toward the tip along the axial direction Da. Also, the movable core 30, which engages with the engagement portion 213 of the valve body 20, moves toward the tip side along the axial direction Da together with the valve body 20. As a result, the tip portion 23 of the valve body 20 is pressed against a seat surface 124a of the injection hole forming member 12, which will be described later, and the flow path FC leading to the injection holes 18, 19 is closed by the valve body 20, resulting in a valve-closed state. As a result, fuel injection by the fuel injection device 1 is stopped.

[0053] 2. Detailed configuration of the injection hole, injection hole forming member, and tip of the valve body Next, the detailed configurations of the injection holes 18, 19, the injection hole forming member 12 and the tip portion 23 of the valve body 20 will be described with reference to Figs. FIG. 3 is an enlarged cross-sectional view of the tip portion of fuel injection device 1, and FIG.

[0054] As shown in Figures 1 and 3, the injection hole forming member 12 representing an orifice cup has a tubular portion 122 press-fitted into the inner wall surface of the first internal space 130 of the nozzle body 10, and a seat portion 124 continuing from the tip end side of the tubular portion 122 in the axial direction Da.

[0055] A tip side sliding portion 231 provided on the tip portion 23 of the valve body 20 slides on the inner circumferential surface 121 of the cylindrical portion 122. A plurality of notches 123 are formed in the cylindrical portion 122. The plurality of notches 123 are formed at equal intervals in the circumferential direction of the inner circumferential surface 121 of the cylindrical portion 122. A flow path FC through which fuel passes is formed between the notches 123 and the tip side sliding portion 231. The flow path FC extends toward the seat portion 124.

[0056] The seat portion 124 is formed continuously with the cylindrical portion 122 so as to close the opening on the tip end side in the axial direction Da of the cylindrical portion 122. The seat portion 124 is a substantially hemispherical recessed portion protruding toward the tip end side in the axial direction Da. A seat surface 124a is formed inside the seat portion 124, with which a spherical portion 230 of the valve body 20 described later comes into contact and separates. The seat surface 124a is formed in a truncated cone shape whose diameter decreases toward the tip end side in the axial direction Da.

[0057] In addition, a sack chamber 125 is formed at the tip of the seat portion 124 in the axial direction Da. The sack chamber 125 is formed at the tip of the seat surface 124a in the axial direction Da, and is a recessed portion that is substantially hemispherical recessed from the seat surface 124a toward the tip side in the axial direction Da. When the seat surface 124a is ground, the sack chamber 125 formed of the recess can provide an escape for a tool performing the grinding process. In addition, the sack chamber 125 is formed on the central axis AX1 of the fuel injection device 1. At least a part of a convex portion 233 of a spherical portion 230 in the valve body 20 described later is inserted into this sack chamber 125.

[0058] The tip portion 23 of the valve body 20 has a spherical portion 230 and a tip side sliding portion 231. The tip side sliding portion 231 slides on the inner circumferential surface 121 of the cylindrical portion 122 of the injection hole forming member 12. The spherical portion 230 is formed continuously on the tip side of the tip side sliding portion 231 in the axial direction Da.

[0059] The spherical portion 230 is formed in a substantially hemispherical shape. The spherical portion 230 has a valve body side seating surface 232 and a convex portion 233. The valve body side seating surface 232 faces the seating surface 124a of the seat portion 124, and approaches and moves away from the seating surface 124a. When the valve body side seating surface 232 contacts the seating surface 124a, a flow path FC leading to the injection holes 18 and 19 described later is closed. When the valve body side seating surface 232 moves away from the seating surface 124a, a flow path FC through which the fuel passes is formed between the valve body side seating surface 232 and the seating surface 124a, and the fuel is injected from the injection holes 18 and 19 described later. When the valve body side seating surface 232 contacts the seating surface 124a, a part of the convex portion 233 is inserted into the sac chamber 125.

[0060] Further, a sack chamber injection hole 18 is formed in the sack chamber 125, and a plurality of (in this example, five) seat portion injection holes 19 are formed in the seat surface 124a.

[0061] The orifice hole 18a extends from the inner wall surface of the sac chamber 125 toward the outer circumferential surface 120. ...

[0062] 2 and 3, the axial direction Fa of the orifice hole 18a (hereinafter referred to as the "injection axis"), which is the direction in which fuel is injected from the sac chamber injection hole 18, faces the spark plug 300. More specifically, the injection axis Fa of the sac chamber injection hole 18 faces the ignition region 300a where a spark is generated in the ignition plug 300. Therefore, the spray F1 injected from the sac chamber injection hole 18 (hereinafter referred to as the "sac chamber spray") faces the ignition region 300a.

[0063] The countersunk hole 18b is a recess recessed from the outer circumferential surface 120 toward the orifice hole 18a, and is formed so as to surround the periphery of the orifice hole 18a. The opening diameter of the countersunk hole 18b is set to be larger than the opening diameter of the orifice hole 18a. In addition, the length from the outer circumferential surface 120 to the orifice hole 18a in the countersunk hole 18b is set to be shorter than the length from the inner wall surface of the sac chamber 125 to the countersunk hole 18b in the orifice hole 18a.

[0064] The seat portion injection hole 19 is formed in a three-stage shape with an orifice hole 19a for forming a spray, a countersunk hole 19b, and a surface pressing hole 19c for forming a flat surface. The orifice hole 19a extends from the seat surface 124a toward the outer peripheral surface 120. The countersunk hole 19b is formed so as to surround the orifice hole 19a, and extends from the end of the orifice hole 19a on the outer peripheral surface 120 side toward the outer peripheral surface 120. The surface pressing hole 19c is a recess recessed from the outer peripheral surface 120 toward the countersunk hole 19b, and is formed so as to surround the periphery of the countersunk hole 19b.

[0065] The seat portion injection hole 19 is formed in the curved surface portion of the injection hole forming member 12. Therefore, a countersunk hole 19b is provided in the seat portion injection hole 19 to adjust the length of the orifice hole 19a. In contrast, the sack chamber injection hole 18 is formed in the tip portion of the injection hole forming member 12. Therefore, by adjusting the thickness of the seat portion 124 at the sack chamber 125, the length of the orifice hole 18a in the sack chamber injection hole 18 can be easily adjusted.

[0066] This eliminates the need to provide a hole for adjusting the length of the orifice hole 18a in the suck chamber injection hole 18. As a result, the processing time for forming the suck chamber injection hole 18 can be reduced.

[0067] Furthermore, since the countersunk hole 18b only needs to form a flat surface, its length can be minimized. As a result, the spray F1 injected from the sac chamber injection hole 18 can be prevented from adhering to the wall surface of the countersunk hole 18b.

[0068] Furthermore, in order to improve the stability of combustion, it is required to stabilize the shape of the spray F1 without allowing air to enter the sac chamber injection hole 18. This makes it possible to suppress adhesion of fuel to the tip of the injection hole forming member 12, thereby improving the stability of combustion. In order to stabilize the shape of the spray F1, it is preferable to increase the internal pressure of the sac chamber injection hole 18. In order to increase the internal pressure of the sac chamber injection hole 18, it is necessary to increase the injection hole length L / injection hole diameter D of the sac chamber injection hole 18.

[0069] However, in order to increase the injection hole length L of the sack chamber injection hole 18, it is necessary to increase the thickness of the sheet portion 124 of the injection hole forming member 12, which is an orifice cup. If the sheet portion 124 is made thicker overall, not only does it increase the risk of breaking the hole punch used to form the sack chamber injection hole 18, but it also affects the machined surface of the other sheet portion injection holes 19. Furthermore, even if only the tip portion of the sheet portion 124 is made thicker, it also affects the thickness of other parts of the sheet portion 124, which similarly affects the machined surface of the sheet portion injection hole 19, making it difficult to form the sheet portion injection hole 19 with the desired dimensions.

[0070] In contrast, in the fuel injection device 1 of this embodiment, the start position of the orifice hole 18a in the sac chamber injection hole 18, i.e., the start end 127 on the rear end side of the axial direction Da, is located on the rear end side of the axial direction Da from the intersection 128 of the imaginary extension line 126 along the seat surface 124a and the central axis AX1. In other words, the start end 127 of the sac chamber injection hole 18 is formed on the convex portion 233 side of the spherical portion 230 in the valve body 20 from the intersection 128 indicating the apex of the imaginary cone formed by the seat surface 124a. This allows the injection hole length L of the orifice hole 18a in the sac chamber injection hole 18 to be extended toward the inside of the injection hole forming member 12.

[0071] In this way, in the fuel injection device 1 of this embodiment, the injection hole length L of the sac chamber injection hole 18 can be increased without changing the outer shape of the injection hole forming member 12. As a result, the internal pressure of the sac chamber injection hole 18 can be increased, and the shape of the spray F1 can be stabilized.

[0072] In this embodiment, the sack chamber 125 in which the sack chamber injection hole 18 is formed is formed as a recessed portion that is substantially hemispherical recessed from the tip of the seat surface 124a of the seat portion 124 toward the tip side in the axial direction Da, but the present invention is not limited to this. For example, the tip of the seat surface 124a of the seat portion 124 may be formed substantially hemispherical instead of conical without providing a recess at the tip of the seat surface 124a. Then, the hemispherical tip of the seat surface 124a may be the sack chamber 125. That is, the sack chamber 125 is smoothly connected to the seat surface 124a. In this case, it is preferable to remove the convex portion 233 in the spherical portion 230 of the valve body 20.

[0073] In this configuration, when the sack chamber injection hole 18 is formed in the sack chamber 125, the start end 127 of the sack chamber injection hole 18 is formed on the protruding portion 233 side of the valve body 20 relative to the intersection 128 indicating the apex of the cone formed by the seat surface 124a. Even in this configuration, the injection hole length L of the sack chamber injection hole 18 can be increased, and the internal pressure of the sack chamber injection hole 18 can be increased.

[0074] Here, even if the start end 127 of the sac chamber injection hole 18 is formed closer to the convex portion 233 of the spherical portion 230 of the valve body 20 than the intersection 128, the volume of the sac chamber 125 increases when the distance between the convex portion 233 and the start end 127 increases. When the volume of the sac chamber 125 increases, the amount of slow-speed spray injected from the sac chamber injection hole 18 increases after the valve body side seat surface 232 and the seat surface 124a come into contact. The slow-speed spray is difficult to atomize, which reduces the stability of combustion. Therefore, in order to reduce the amount of slow-speed spray injected from the sac chamber injection hole 18, it is preferable to shorten the distance between the start end 127 and the convex portion 233. Furthermore, when the valve body side seat surface 232 and the seat surface 124a are in contact, it is desirable that the distance between the tip of the convex portion 233 and the starting end portion 127 of the sack chamber injection hole 18 be 1.7 times or less the distance between the starting end portion 127 of the sack chamber injection hole 18 and the intersection point 128.

[0075] In this example, the sack chamber injection hole 18 is formed in two stages and the seat portion injection hole 19 is formed in three stages, but the number of stages of the sack chamber injection hole 18 and the seat portion injection hole 19 is not limited to this. For example, the sack chamber injection hole 18 may be formed in three or more stages and the seat portion injection hole 19 may be formed in four or more stages, or the sack chamber injection hole 18 and the seat portion injection hole 19 may be formed in a single stage with only the orifice holes 18a, 19a. In order to reduce the processing time of the sack chamber injection hole 18, it is preferable to set the number of stages of the sack chamber injection hole 18 to be less than the number of stages of the seat portion injection hole 19.

[0076] 4, the multiple seat portion injection holes 19 are formed at approximately equal intervals except for a portion around the sac chamber injection hole 18. Specifically, the multiple seat portion injection holes 19 are not formed on the spark plug 300 side of the sac chamber injection hole 18 in the injection hole forming member 12. In other words, the sac chamber injection hole 18 is disposed on the spark plug 300 side of the multiple seat portion injection holes 19.

[0077] FIG. 5 is an external perspective view showing the spray injected from the fuel injection device 1. As shown in FIG. As described above, the injection axis Fa of the sac chamber injection hole 18 faces the spark plug 300, and the sac chamber injection hole 18 is disposed closer to the spark plug 300 than the plurality of seat portion injection holes 19. Therefore, as shown in Fig. 2 and Fig. 5, the sac chamber spray F1 approaches the spark plug 300 closest to the spray F2 injected from the plurality of seat portion injection holes 19 (hereinafter referred to as "seat portion spray").

[0078] Furthermore, the multiple seat portion injection holes 19 are arranged so as not to completely surround the sack chamber injection hole 18. This makes it possible to prevent the sack chamber spray F1 and the multiple seat portion sprays F2 from interfering with each other, i.e., the occurrence of so-called spray shrink. This makes it possible to prevent the sprays F1 and F2 from interfering with each other, thereby preventing an increase in the spray length (penetration), which is the length from the outer circumferential surface 120 of the injection hole forming member 12 to the arrival of the spray droplets.

[0079] Note that if the angle between the injection axis Fa of the sac chamber injection hole 18 and the injection axes of the multiple seat portion injection holes 19 can be made large, the multiple seat portion injection holes 19 may be arranged to completely surround the sac chamber injection hole 18. In other words, the seat portion injection hole 19 may be arranged closer to the spark plug than the sac chamber injection hole 18.

[0080] However, due to Bernoulli's theorem, there is a risk that the multiple seat portion sprays F2 will be attracted to the sac chamber spray F1. Therefore, as in the fuel injection device 1 of this example, it is desirable to arrange the multiple seat portion injection holes 19 so as not to be arranged in a portion of the periphery of the sac chamber injection hole 18, but to not surround the entire periphery of the sac chamber injection hole 18.

[0081] FIG. 6 is an explanatory diagram showing, in an enlarged scale, the state in which fuel is injected from the sac chamber injection hole 18 and the seat portion injection hole 19. As shown in FIG. Here, the fuel during or after injection is collected on the central axis AX1 on the outer peripheral surface 120 of the injection hole forming member 12. Therefore, the central axis AX1 on the outer peripheral surface 120 of the injection hole forming member 12 is the location to which fuel is most likely to adhere. In contrast, in the fuel injection device 1 of this example, the sac chamber injection hole 18 is formed on the central axis AX1 of the injection hole forming member 12.

[0082] When fuel is injected from the sack chamber injection hole 18, the gas pressure near the sack chamber spray F1 drops according to Bernoulli's theorem. Therefore, a force acts on the fuel adhering to the outer peripheral surface 120, attracting it to the sack chamber spray F1. As a result, the fuel adhering to the outer peripheral surface 120 is attracted to the sack chamber spray F1 and is removed from the outer peripheral surface 120 together with the sack chamber spray F1. As a result, it is possible to suppress the fuel from adhering to the tip of the injection hole forming member 12, and improve the stability of combustion.

[0083] Furthermore, the sac chamber injection hole 18 has a two-stage shape consisting of an orifice hole 18a and a countersunk hole 18b, and the opening diameter of the countersunk hole 18b is formed to be larger than the opening diameter of the orifice hole 18a. Furthermore, the length of the countersunk hole 18b is formed to be shorter than the length of the orifice hole 18a. This makes it possible to increase the force with which the sac chamber spray F1 attracts the fuel adhering to the outer peripheral surface 120 according to the above-mentioned Bernoulli's theorem, and to more efficiently remove the fuel from the outer peripheral surface 120.

[0084] Furthermore, when the fuel passes through the flow path FC, bubbles S1 called cavitation are generated in the fuel. The bubbles S1 are generated when the flow path FC narrows, causing the flow rate to increase and drop below the saturated vapor pressure of the fuel. The flow path FC between the valve body side seat surface 232 and the seat surface 124a is the narrowest part of the fuel injection device 1. Therefore, the bubbles S1 are generated in the flow path FC formed between the valve body side seat surface 232 and the seat surface 124a, which is located from the vicinity of the seat portion 124 of the injection hole forming member 12 to the tip end side.

[0085] The bubble S1 passes through the flow path FC together with the fuel and flows to the sack chamber 125 located on the central axis AX1 of the fuel injection device 1. The bubble S1 then collapses in the sack chamber 125. The collapse energy T1 generated by the collapse of the bubble S1 can promote the atomization of the fuel in the sack chamber 125. As a result, the fuel can be injected in a more atomized state from the sack chamber injection hole 18 provided in the sack chamber 125.

[0086] Furthermore, in the sack chamber injection hole 18 into which fuel flows in from all 360° directions of the seat portion 124, the length of the sack chamber spray F1 at the beginning of the spray is longer than the seat portion spray F2. Furthermore, as described above, the injection axis Fa of the sack chamber injection hole 18 is directed toward the ignition region 300a of the spark plug 300. Therefore, even if the length of the spray of the seat portion spray F2 becomes shorter, it is possible to maintain or improve the combustion stability at fast idle.

[0087] In addition, the seat portion injection hole 19 is not disposed closer to the spark plug 300 than the sac chamber injection hole 18. This prevents the seat portion spray F2 from reaching the cylinder head, intake valve, exhaust valve, etc. of the internal combustion engine, and prevents fuel from adhering to the cylinder head, intake valve, or exhaust valve.

[0088] The present invention is not limited to the embodiment described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention as defined in the claims.

[0089] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but may also mean a "substantially parallel" or "substantially orthogonal" state that includes "parallel" and "orthogonal" and is within a range in which the respective functions can be exerted. [Explanation of symbols]

[0090] 1...fuel injection device, 10...nozzle body, 12...injection hole forming member, 18...sac chamber injection hole (injection hole), 18a, 19a...orifice hole, 18b, 19b...countersunk hole, 19...seat portion injection hole, 19c...face pressing hole, 20...valve body, 23...tip portion, 30...movable core, 40...fixed core, 50...coil, 70...housing, 80...connection portion, 120...outer peripheral surface, 121...inner peripheral surface, 122...tubular portion, 123...notch portion, 124...seat portion, 124a...seat surface, 125...sac chamber, 126...imaginary extension line, 127...start end portion, 128...intersection (vertex), 230...spherical portion, 231...tip side sliding portion, 232...valve body side seat surface, 233...projection, 300...spark plug, 300a...ignition area, 301...cylinder, 302...piston, 310...combustion chamber, AX1...central axis, Da...axial direction, F1...sac chamber spray, F2...seat portion spray, S1...bubble, T1...collapse energy

Claims

1. A nozzle body that is installed in a cylinder of an internal combustion engine in which an ignition plug is arranged; an injection hole forming member provided at a tip portion of the nozzle body; a valve body having a valve body-side seat surface that comes into contact with and separates from a seat surface provided on the injection hole forming member, The injection hole forming member is A seat portion having the seat surface; A sac chamber formed at a tip portion of the seat portion, The sac chamber is formed with a sac chamber injection hole for injecting fuel toward the spark plug, The start end portion, which is the end portion on the rear end side of the valve body in the axial direction of the sac chamber injection hole, is located on the valve body side of the apex of a virtual cone formed when the seat surface is extended. Fuel injection device.

2. The sac chamber is a recess recessed from the seat surface toward the tip end side.

2. The fuel injection system of claim 1.

3. The central axis of the sac chamber injection hole is inclined with respect to the central axis of the nozzle body.

2. The fuel injection system of claim 1.

4. The injection axis, which is the direction in which the fuel is injected from the sac chamber injection hole, is oriented toward an ignition region in which a spark is generated in the spark plug.

4. A fuel injection system according to claim 3.

5. The tip position of the valve body is at least partially inserted into the sac chamber in a valve closed state, The distance between the tip position of the valve body and the start end of the sac chamber injection hole is set to 1.7 times or less as compared with the distance between the apex of the virtual cone formed by the seat surface and the start end of the sac chamber injection hole.

3. A fuel injection system according to claim 2.

6. The sac chamber injection hole is an orifice hole extending from an inner wall surface of the sac chamber toward an outer circumferential surface of the injection hole forming member; a countersunk hole which is a recess recessed from the outer circumferential surface toward the orifice hole; 2. The fuel injection system of claim 1, comprising:

7. The opening diameter of the countersunk hole is set to be larger than the opening diameter of the orifice hole.

7. A fuel injection system according to claim 6.

8. The length from the outer circumferential surface to the orifice hole in the countersunk hole is set shorter than the length from the inner wall surface of the sac chamber to the countersunk hole in the orifice hole.

7. A fuel injection system according to claim 6.

9. The seat surface is formed with a seat portion injection hole for injecting the fuel.

2. The fuel injection system of claim 1.

10. The seat portion injection hole is formed in a plurality of parts on the seat surface, The plurality of seat portion injection holes are not disposed at least partially around the sac chamber injection hole.

10. A fuel injection system as claimed in claim 9.

11. The sac chamber injection hole is disposed on the injection hole forming member closer to the spark plug than the seat portion injection hole.

11. A fuel injection system according to claim 10.

12. The sac chamber injection hole and the seat portion injection hole are formed in a multi-stage shape, The number of stages of the sac chamber injection holes is set to be less than the number of stages of the seat portion injection holes.

12. A fuel injection system as claimed in claim 11.

Images