JP2013096242A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve spray diffusion in a fuel injection valve having a slit nozzle hole.SOLUTION: In the fuel injection valve 101 for injecting fuel into a combustion chamber of an engine, a sack part 26 in which fuel accumulates is formed inside a valve seat part 23 of a nozzle body 211. The sack part 26 is formed with two inclined slit nozzle holes 71, 72. The first slit nozzle hole 71 has its inlet formed in the bottom wall 261 of the sack part 26. The second slit nozzle hole 72 has its inlet formed in the inner side wall 262 of the sack part 26 on the needle 301 side with respect to the inlet of the first slit nozzle hole 71. Thereby, compared with a fuel injection valve having only one slit nozzle hole, the spray diffusion range is widened for improving spray diffusion. Moreover, since the sack central axis Zs and the needle central axis Zn are offset, balance of the fuel amounts flowing into the two slit nozzle holes 71, 72 is varied according to the needle lift amount so as to enable further spray diffusion.

Description

  The present invention relates to a fuel injection valve that injects and supplies fuel.

  2. Description of the Related Art Conventionally, there is known a fuel injection valve that injects fuel into an engine combustion chamber or the like and has an injection hole having a slit shape (Patent Documents 1 and 2). In this fuel injection valve, the fuel injected from the slit-shaped nozzle hole becomes a flat liquid film near the slit-shaped nozzle hole. This liquid film decreases in thickness as it moves away from the slit-shaped nozzle hole, and increases the contact area with the surrounding air, so the liquid film is torn off by the surrounding air and rapidly changes to a fine spray. . For this reason, atomization of the spray is promoted as compared with the circular nozzle hole. Further, the spray reach distance and penetration force can be appropriately adjusted by the slit width W and length L.

Japanese Patent Laid-Open No. 03-78562 JP 2003-314359 A

  However, the fuel injection valves described in Patent Documents 1 and 2 have one slit-shaped nozzle hole, and the flow of fuel flowing into the inlet of the slit-shaped nozzle hole from the sac portion at the tip of the fuel passage is a needle. It does not change greatly depending on the lift amount. Therefore, the angle (spraying direction) of the spray sprayed from the slit-shaped nozzle hole is kept substantially constant. Therefore, there exists a problem that spray cannot fully be spread | diffused.

  The present invention has been made in view of the above points, and an object thereof is to improve spray diffusion in a fuel injection valve having slit-like injection holes.

The fuel injection valve according to claim 1 includes a valve body and a needle.
The valve body includes a fuel passage communicating from one end to the other end in the axial direction, a valve seat portion formed on the inner wall of the fuel passage, a sac portion formed downstream of the valve seat portion in the fuel flow direction, and in which fuel is accumulated, and A plurality of slit-shaped nozzle holes communicating the bottom wall or inner side wall of the sack portion and the outer wall are provided.
The needle is accommodated in the valve body so as to be capable of reciprocating in the axial direction, and shuts off the inflow of fuel to the sac portion when the tip portion comes into contact with the valve seat portion.

  The plurality of slit-shaped nozzle holes are formed on the inner wall of the sac portion on the needle side of the first slit-shaped nozzle hole that is formed on the bottom wall of the sack portion and on the needle side of the inlet of the first slit-shaped nozzle hole. A second slit-shaped nozzle hole. The first slit-shaped nozzle hole and the second slit-shaped nozzle hole are inclined from the inlet toward the outlet toward the side where the inlet of the second slit-shaped nozzle is formed with respect to the central axis of the valve body.

  As described above, the fuel injection valve according to claim 1 has a plurality of slit-shaped nozzle holes including the first slit-shaped nozzle hole and the second slit-shaped nozzle hole, and the first slit-shaped nozzle hole and the second slit. The nozzle holes are inclined to the same side with respect to the central axis of the valve body (hereinafter referred to as “body central axis”). Therefore, the fuel spray injected from the first slit-shaped nozzle hole and the second slit-shaped nozzle hole is inclined to one side with respect to the body center axis.

In other words, this fuel injection valve ensures a certain directivity in the fuel injection direction and expands the spray diffusion range compared to the conventional fuel injection valve having only one slit-like injection hole. Diffusion can be improved.
In addition to the first slit-shaped nozzle hole and the second slit-shaped nozzle hole, the valve body has a third or more slit-shaped nozzle hole, or a non-slit-shaped circular or elliptical nozzle hole. May be.

  According to the second aspect of the present invention, the sack center axis, which is the center axis of the sack portion, is offset to the opposite side to the inlet of the second slit-shaped nozzle hole with respect to the needle center axis, which is the center axis of the needle. . And according to the change of the needle lift amount from the state in which the tip of the needle is in contact with the valve seat to the fully open state, the needle flows into the first slit-shaped nozzle hole and the second slit-shaped nozzle hole. The fuel balance changes.

  When the fuel injection valve is opened, the needle lift amount sequentially changes from the state where the tip of the needle is in contact with the valve seat portion to the fully open (full lift) state. At this time, the fuel flow changes depending on the width of the fuel passage between the tip of the needle and the valve seat of the valve body. Therefore, by utilizing this change in the flow of fuel, by changing the balance of the amount of fuel flowing into the first slit-shaped nozzle hole and the second slit-shaped nozzle hole in accordance with the needle lift amount, the direction of spray is moved, Further, the spray can be diffused.

One of the characteristic configurations for this purpose is that the sack center axis is offset from the needle center axis on the side opposite to the entrance of the second slit-shaped nozzle hole.
In this configuration, at the time of a small lift with a relatively small lift amount, the fuel flowing down the valve seat portion flows down directly to the bottom wall of the sack portion. Therefore, it is easy to flow into the 1st slit-like nozzle hole in which an inlet is formed in the bottom wall of a sac part, and it is hard to flow into the 2nd slit-like nozzle hole in which an inlet is formed in the inner wall of a sack part.
On the other hand, at the time of a large lift with a relatively large lift amount, the ratio of the fuel flowing into the second slit-shaped nozzle hole along the inner wall of the sac portion relatively increases.
This mechanism will be described in detail in the description of the embodiment with reference to the drawings.

In the second aspect of the present invention, there are roughly two possible configurations for offsetting the sack central axis and the needle central axis based on the relationship with the body central axis.
First, as in the third aspect of the invention, “the needle center axis coincides with the body center axis, and the sack center axis is offset to the opposite side of the inlet of the second slit-shaped nozzle hole with respect to the body center axis. It is a configuration. On the contrary, the second is a configuration in which “the sack center axis coincides with the body center axis and the needle center axis is offset with respect to the body center axis toward the inlet side of the second slit-shaped nozzle hole”.

  Here, when the configuration of the invention according to claim 3 is adopted, the machining is relatively easy because the part to be eccentrically processed is only the sack part in the machining of the bottom of the valve body. Moreover, the needle center axis and the body center axis coincide with each other, and the tip of the needle and the valve seat can be coaxial. Therefore, the valve closing operation is stable, which is advantageous.

Further, according to the invention described in claim 4, the valve body in the invention described in claim 3 is configured such that the tip of the needle is located at the boundary between the valve seat portion and the sac portion on the opposite side to the offset side of the sack center axis. A base portion is provided to project so as to narrow the width of the fuel passage between them.
Thereby, at the time of a small lift, the fuel that flows down the valve seat part on the inlet side of the second slit-shaped nozzle hole jumps forward of the flow using the base part as a jumping base, and thus may flow down along the inner wall of the sack part. It is suppressed. Therefore, it is easier to flow into the first slit-shaped nozzle hole, and it is difficult to flow into the second slit-shaped nozzle hole.

The invention according to claim 5 is different from the invention according to claim 2 in that “the balance of the amount of fuel flowing into the first slit-shaped nozzle hole and the second slit-shaped nozzle hole is changed according to the needle lift amount”. This shows another characteristic configuration for the purpose.
According to the fifth aspect of the present invention, the valve body is formed on the bottom wall of the sack portion opposite to the inlet of the second slit-shaped nozzle hole with respect to the inlet of the first slit-shaped nozzle hole. A step portion located on the needle side from the inlet is provided. In the present invention, the sack center axis and the needle center axis may be coaxial.

In this configuration, at the time of a small lift with a relatively small lift amount, the fuel that flows down the valve seat portion flows down directly to the bottom wall of the sac portion and easily flows into the first slit-shaped nozzle hole. On the other hand, during a large lift with a relatively large lift amount, the flow of fuel that flows along the inner wall on the opposite side of the inlet of the second slit-shaped nozzle hole of the sack portion causes the step portion to enter the inlet of the first slit-shaped nozzle hole. By jumping over, it is difficult to flow into the first slit nozzle hole. Therefore, the ratio of the fuel flowing into the second slit-shaped nozzle hole along the inner wall of the sac portion relatively increases.
This mechanism will also be described in detail in the description of the embodiment with reference to the drawings.

In addition, according to the invention described in claim 6, in common with the fuel injection valve described in claims 1-5, the angle of the first slit-shaped nozzle hole with respect to the body central axis is the second slit-shaped nozzle hole. Is formed relatively larger than the angle with respect to the body central axis. In other words, when the body central axis is viewed in the vertical direction, the first slit-shaped nozzle hole has a relatively small gradient, and the second slit-shaped nozzle hole has a relatively large gradient. Therefore, the first slit-shaped nozzle hole and the second slit-shaped nozzle hole are formed so as to approach each other from the inlet toward the outlet.
Further, the outlet of the first slit-shaped nozzle hole and the outlet of the second slit-shaped nozzle hole are formed at overlapping positions.

The invention according to claim 6 further has an object of “promoting atomization”. In the first place, the slit-shaped nozzle hole increases the contact area with air as the spray forms a liquid film, and the liquid film is torn off by the surrounding air. It is advantageous for promotion.
In addition, according to the invention described in claim 6, the cavitation formed at the entrance of the slit-shaped nozzle hole, that is, "the fuel once vaporized and liquefied again" collides at the overlapping exit and collapses. The spray is further diffused by the decay energy of the cavitation, and atomization is promoted.

It is sectional drawing of the fuel injection valve by 1st Embodiment of this invention. It is a schematic diagram of the state which mounted the fuel injection valve by 1st Embodiment of this invention in the engine. (A): It is a front-end | tip part enlarged view of FIG. (B): It is a b arrow view of (a). (C): It is cc sectional drawing of (a). (D): It is dd sectional drawing of (a). It is a schematic diagram which shows the fuel-injection state at the time of (a) small lift and (b) large lift of the fuel injection valve by 1st Embodiment of this invention. It is the graph which compared the spreading | diffusion diffusion (shortening of spray length) effect of the fuel injection valve by 1st Embodiment of this invention, and the fuel injection valve of a comparative example. It is a schematic diagram explaining the atomization effect by the collision of cavitation in the fuel injection valve by 1st Embodiment of this invention. It is a schematic diagram which shows the fuel-injection state at the time of (a) small lift and (b) large lift of the fuel injection valve by 2nd Embodiment of this invention. It is a schematic diagram which shows the fuel-injection state at the time of (a) small lift and (b) large lift of the fuel injection valve by 3rd Embodiment of this invention.

Hereinafter, an embodiment in which a fuel injection valve according to the present invention is mounted on an engine will be described with reference to the drawings.
(First embodiment)
A fuel injection valve according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 2 shows an overall configuration of a direct injection gasoline engine (hereinafter simply referred to as an engine) 60 equipped with a fuel injection valve 101.

  As shown in FIG. 2, the fuel injection valve 101 is attached to the cylinder head 61 and injects fuel directly into the combustion chamber 64. The combustion chamber 64 is formed from the wall surface of the cylinder head 61, the inner wall surface 65 of the cylinder block 62, and the upper end surface 67 of the piston 66. The fuel injection valve 101 is supplied with fuel pressurized to a fuel injection pressure from a fuel supply pump (not shown).

  The fuel injection valve 101 is attached to the corner of the cylinder head 61 on the intake valve 68 side in an oblique direction with respect to the axis of the combustion chamber 64. An ignition device 63 for igniting combustible air mixed with fuel is mounted at the center position of the cylinder head 61.

  The fuel injection valve 101 injects fuel in a direction toward the upper end surface 67 of the piston 66, that is, a direction inclined with respect to the axis Z direction. In the present embodiment, fuel is injected from two slit-shaped injection holes 71 and 72 formed at the tip of the fuel injection valve 101. Here, if the penetrating force of the fuel injection valve is large and the spray length is long, the spray adheres directly to the cylinder wall surface 65 and the upper end surface 67 of the piston 66, and it becomes easy to generate PM (particulate matter) and deposits. Therefore, it is desired to make the spray length as short as possible. Therefore, the fuel injection valve 10 of the present embodiment has a feature in the configuration of the slit-shaped injection hole so as to shorten the spray length while improving the diffusion of the spray.

Next, the basic configuration of the fuel injection valve 101 will be described mainly with reference to FIGS. In the following description, the upper side of FIG. 1 is represented as “upper” and the lower side of FIG. 1 is represented as “lower”.
As shown in FIG. 1, the housing 11 of the fuel injection valve 101 is formed in a cylindrical shape. The housing 11 has a first magnetic part 12, a nonmagnetic part 13, and a second magnetic part 14. The nonmagnetic part 13 prevents a magnetic short circuit between the first magnetic part 12 and the second magnetic part 14. The 1st magnetic part 12, the nonmagnetic part 13, and the 2nd magnetic part 14 are integrally connected by laser welding etc., for example.

  An inlet member 15 having a fuel inlet 16 is fixed to the upper end of the housing 11 in the axial direction by press-fitting or the like. Fuel is supplied to the fuel inlet 16 from a fuel supply pump (not shown). Foreign matter is removed from the fuel supplied to the fuel inlet 16 by the fuel filter 17 and flows into the housing 11.

A cylindrical nozzle holder 20 is connected to the lower end of the housing 11. A bottomed cylindrical nozzle body 211 is fixed to the nozzle holder 20 at the lower end of the nozzle holder 20 by press-fitting or welding. In the present embodiment, the housing 11, the nozzle holder 20, and the nozzle body 211 correspond to a “valve body” recited in the claims.
Here, the body central axis Zb, which is the central axis of the nozzle body 211, is provided coaxially with the central axis of the entire fuel injection valve 101, that is, the central axis of the housing 11, the drive unit 40, and the like. Hereinafter, the body center axis Zb is treated as representing the center axis of the entire fuel injection valve 101.

The nozzle body 211 has a tapered valve seat portion 23 formed at the hole bottom on the tip side. In addition, a concave sack portion 26 in which fuel is accumulated is formed on the inner side of the valve seat portion 23. The sack portion 26 is formed with two slit-shaped injection holes 71 and 72 that are inclined with respect to the body center axis Zb. A detailed configuration related to the sack portion 26 and the slit-like nozzle holes 71 and 72 will be described later.
A space between the inner wall of the nozzle body 211 and the outer wall of the needle 301 forms a fuel passage 24.

The needle 301 is accommodated in the housing 11, the nozzle holder 20, and the nozzle body 21 constituting the “valve body” so as to be capable of reciprocating in the axial direction.
The needle 301 includes a shaft part 31, a head part 32, and a tip part 331. As shown in FIG. 3A, the distal end portion 331 has three stages of tapered surfaces, a first tapered surface 34, a second tapered surface 35, and a third tapered surface 36. A boundary portion between the first tapered surface 34 and the second tapered surface 35 constitutes a sheet portion 37. Further, a fuel passage 25 connected from the fuel passage 24 is formed between the first to third tapered surfaces 34, 35, 36 and the valve seat portion 23.
By reciprocating the needle 301 in the axial direction, the seat portion 37 comes into contact with or separates from the valve seat portion 23 (see FIG. 3) of the nozzle body 21, and the flow of fuel from the fuel passage 25 to the sac portion 26 is blocked. Or tolerate.

The drive unit 40 for driving the needle 301 includes a spool 41, a coil 42, a fixed core 43, a plate housing 44, and a movable core 50.
The spool 41 is provided on the outer diameter side of the housing 11. The spool 41 is formed of a resin material in a cylindrical shape, and a coil 42 is wound around the spool 41. Both ends of the wound coil 42 are electrically connected to the terminal portion 46 of the connector 45.
A fixed core 43 is provided on the inner side of the coil 42 across the housing 11. The fixed core 43 is formed in a cylindrical shape from a magnetic material such as iron, and is fixed to the housing 11 by, for example, press fitting. The plate housing 44 is made of a magnetic material and covers the outer diameter of the coil 42.

  The movable core 50 is provided on the same axis as the fixed core 43, and can reciprocate in the axial direction inside the housing 11. The movable core 50 is formed in a cylindrical shape from a magnetic material such as iron. The movable core 50 has a cylindrical portion 51 on the lower side opposite to the fixed core 43, and the head portion 32 of the needle 301 is press-fitted into the cylindrical portion 51. Thereby, the needle 301 and the movable core 50 reciprocate integrally. In addition, a plurality of communication holes 54 that communicate the inside of the movable core 50 and the outside of the needle 301 are formed in the cylinder portion 51.

A spring 18 is provided at the end of the movable core 50 on the fixed core 43 side. The spring 18 has a biasing force extending in the axial direction, and is installed so that both ends of the spring 18 are sandwiched between the movable core 50 and the adjusting pipe 19. The spring 18 urges the movable core 50 and the needle 301 in a direction to contact the valve seat portion 23.
The adjusting pipe 19 is fixed to the fixed core 43 by, for example, press fitting, and the biasing force (load) of the spring 18 is adjusted by adjusting the press fitting length.
The fuel that has flowed into the housing 11 from the fuel inlet 16 via the filter 17 passes through the inside of the adjusting pipe 19 and the spring 18, and further passes through the communication hole 54 and the outside of the needle 301 to the fuel passage. To 24.

Next, the configuration of the tip of the nozzle body 211, which is a characteristic configuration of the present invention, will be described in detail with reference to FIG.
As shown in FIG. 3, the first slit-shaped injection hole 71 has an inlet 711 formed in the bottom wall 261 of the sack portion 26. The second slit-shaped injection hole 72 has an inlet 721 formed on the inner wall 262 of the sac portion 26 on the needle 301 side with respect to the inlet 711 of the first slit-shaped injection hole 71.
The first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72 have slit shapes in which the opening shapes of the outlets 712 and 722 are a width W and a length L. The length L is, for example, not less than 4.5 times the width W.

In the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72, the inlet 721 of the second slit-shaped nozzle hole 72 is formed with respect to the body center axis Zb from the inlets 711, 721 toward the outlets 712, 722. It is inclined to the side.
In the present embodiment, the needle center axis Zn coincides with the body center axis Zb, and the sack center axis Zs is opposite to the body center axis Zb from the inlet 721 of the second slit-shaped injection hole 72 (left side in FIG. 3). ) Is offset. The offset amount is preferably equal to or greater than the full lift amount of the needle 301, for example.

Further, when the needle center axis Zn is viewed in the vertical direction as shown in FIG. 3A, the first slit-shaped nozzle hole 71 has a relatively small gradient, and the second slit-shaped nozzle hole 72 has a relatively gradient. large. Therefore, the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72 approach each other from the inlets 711 and 721 toward the outlets 712 and 722.
Particularly in this embodiment, the outlet 712 of the first slit-shaped nozzle hole 71 and the outlet 722 of the second slit-shaped nozzle hole 72 are formed at overlapping positions. Here, a virtual plane passing through the center of the gradient between the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72 is represented as a virtual center plane Jo.

  In the nozzle body 211, the valve seat portion 23 is formed symmetrically with respect to the needle central axis Zn, and the sac portion 26 is formed symmetrically with respect to the sac central axis Zs. Therefore, the boundary between the valve seat portion 23 and the sac portion 26 is continuous on the left side of FIG. 3A, whereas a discontinuous base portion 263 is formed on the right side of FIG. . The base portion 263 projects inward from the valve seat portion 23 so as to narrow the width of the fuel passage 25 between the base portion 263 and the tip portion 331 of the needle 301.

(Operation)
Next, the operation of the fuel injection valve 101 having the above configuration will be described.
When energization of the coil 42 is stopped, no magnetic attractive force is generated between the fixed core 43 and the movable core 50. Therefore, the movable core 50 and the needle 301 are pressed downward by the urging force of the spring 18. Then, the seat portion 37 of the needle 301 comes into contact with the valve seat portion 23, and fuel injection from the slit-shaped injection holes 71 and 72 is blocked.

When the coil 42 is energized from the closed state, a magnetic circuit is formed by the magnetic field generated in the coil 42. Thereby, a magnetic attractive force is generated between the fixed core 43 and the movable core 50.
When the magnetic attractive force generated between the fixed core 43 and the movable core 50 becomes larger than the urging force of the spring 18, the movable core 50 and the needle 301 start moving upward. As a result, the seat portion 37 of the needle 301 is separated from the valve seat portion 23.

  The fuel that has flowed into the fuel injection valve 101 from the fuel inlet 16 via the filter 17 is inside the inlet member 15, inside the adjusting pipe 19, inside the fixed core 43, inside the movable core 50, and the communication hole 54. The fuel passage 24 is reached via the outside of the needle 301 in sequence. The fuel in the fuel passage 24 flows into the sack portion 26 via the fuel passage 25 between the seat portion 37 of the needle 301 and the valve seat portion 23, and is injected from the slit-shaped injection holes 71 and 72.

  At this time, as described below, in the fuel injection valve 101 of the present embodiment, the direction in which fuel is injected changes according to the lift amount of the needle 301, and the spray diffusion range throughout the entire lift period is expanded. At the same time, the spray length is shortened. Thereby, generation | occurrence | production of PM (particulate matter) and a deposit by spray adhering directly to the cylinder wall surface 65 or the upper end surface 67 of the piston 66 is suppressed.

  When energization to the coil 42 is stopped from the valve open state, the magnetic attractive force between the fixed core 43 and the movable core 50 disappears. When the magnetic attractive force becomes smaller than the urging force of the spring 18, the movable core 50 and the needle 301 move downward by the urging force of the spring 18. Then, the seat portion 37 of the needle 301 comes into contact with the valve seat portion 23 again, the flow of fuel between the fuel passage 25 and the sac portion 26 is interrupted, and fuel injection ends.

Next, the effect of the fuel injection when the fuel injection valve 101 is opened will be described in detail with reference to FIGS.
At the time of the small lift shown in FIG. 4A, the fuel having a relatively high flow velocity that has passed through the relatively narrow fuel passage 25 between the tip 331 of the needle 301 and the valve seat 23 of the nozzle body 212 is the sack portion 26. It flows down to the bottom wall 261 in the vicinity of the center of the gas and easily flows into the first slit-shaped nozzle hole 71. In particular, the fuel flow FLa on the offset side (left side in FIG. 4) of the sack center axis Zs is relatively easy to flow into the first slit-like nozzle hole 71 because the distance to the center of the sack portion 26 is short.

On the other hand, the fuel flow FLb on the non-offset side (right side in FIG. 4) of the sack center axis Zs has a long distance to the center of the sack portion 26. However, the base part 263 formed at the boundary between the valve seat part 23 and the inner wall 262 of the sack part 26 narrows the width of the fuel passage 25 between the base part 263 and the front end part 331, and the fuel flow FLb. Increase the flow rate. In addition, the fuel flowing down the valve seat portion 23 is prevented from flowing along the inner wall 262 by jumping forward of the flow with the base portion 263 as a jump base. Therefore, the fuel flow FLb is less likely to flow into the second slit-shaped injection hole 72.
That is, at the time of a small lift, the flow into the first slit-shaped nozzle hole 71 has priority over the flow into the second slit-shaped nozzle hole 72. Therefore, the average surface JL of the spray SL at the time of the small lift is closer to the upper side than the virtual center plane Jo.

On the other hand, at the time of the large lift shown in FIG. 4B, the fuel having a relatively low flow velocity that has passed through the relatively wide fuel passage 25 flows down along the inner wall 262 of the sack portion 26. Then, on the right side of FIG. 4, the ratio of the fuel flowing into the second slit-shaped injection holes 72 in the fuel flow FHb flowing down along the inner wall 262 relatively increases. In addition, part of the fuel that has passed through the inlet of the first slit-shaped nozzle hole 71 in the bottom wall 261 of the fuel flow FHa flowing down the left inner wall 262 also flows into the second slit-shaped nozzle hole 72.
That is, at the time of a large lift, the ratio of the fuel flowing into the second slit-shaped injection hole 72 is relatively increased. Therefore, the average surface JH of the spray SH at the time of a large lift is closer to the lower side than the virtual center plane Jo.

Thus, the fuel injection valve 101 changes the balance of the amount of fuel flowing into the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72 according to the needle lift amount, so that the direction of the average surface of the spray Can be used to spread the spray.
Here, with reference to FIG. 5, the “spray diffusion effect” by the fuel injection valve 101 of the present embodiment will be described in comparison with a comparative example. The fuel injection valve of the comparative example corresponds to the prior art described in Patent Documents 1 and 2, and has only one slit-shaped injection hole.

  FIGS. 5A, 5 </ b> B, and 5 </ b> C show changes in spray length, needle lift amount, and energization on / off of the drive unit 40 on a common time axis. Initially, the fuel injection valve 10 is closed. When the drive unit 40 is energized at time t0, the needle 301 starts to rise (lift) at time t1 after a slight time lag. As a result, the passage from the fuel passage 25 to the sac portion 26 is opened, and spraying from the slit-shaped injection holes 71 and 72 is started. Thereafter, while the needle 301 is being lifted (during valve opening), fuel injection continues. At this time, the spray length is gradually increased by superimposing the spray sprayed later on the spray sprayed earlier. Energization of the drive unit 40 is turned off at time t2.

The needle 301 is fully opened at time t3. When the magnetic attractive force disappears, the needle 301 starts to descend due to the urging force of the spring 18 and closes at time t4. On the other hand, since the accumulation of new sprays is eliminated, the spray length gradually becomes constant.
Here, as shown to Fig.5 (a), the fuel injection valve 101 of this embodiment can shorten spray length about 30% compared with the fuel injection valve of a comparative example.

  The reason for this can be explained as follows. That is, the fuel injection valve of the comparative example has only one slit-like injection hole, and the spray direction is constant according to the change in the needle lift amount. On the other hand, the fuel injection valve of the present embodiment has two slit-shaped injection holes 71 and 72 having different spray directions, and can change the spray direction according to the change in the needle lift amount. Therefore, the spray diffusion range can be expanded. As a result, the spray length can be shortened compared to the comparative example. Therefore, generation | occurrence | production of PM and a deposit can be suppressed.

Next, the “spray atomization effect” by the fuel injection valve 101 of the present embodiment will be described with reference to FIG. FIG. 6 schematically shows the cavitation of fuel in the slit injection holes 71 and 72, that is, “a phenomenon in which once vaporized fuel is liquefied again”.
In the first place, the slit-shaped nozzle hole increases the contact area with air as the spray forms a liquid film, and the liquid film is torn off by the surrounding air. It is advantageous for promotion.

  In addition, as shown in FIG. 6, the fuel injection valve 101 of the present embodiment is formed at a position where the outlet 712 of the first slit-shaped nozzle hole 71 and the outlet 722 of the second slit-shaped nozzle hole 72 overlap. Yes. Therefore, the cavitation Cv formed at the inlets 711 and 721 of the slit-shaped nozzle hole collides at the outlets 712 and 722 and collapses. The spray is further diffused by the decay energy of the cavitation Cv, and atomization is promoted.

  Next, the fuel injection valves according to the second and third embodiments of the present invention will be described with reference to the enlarged sectional views of the distal ends of FIGS. These fuel injection valves are common to the fuel injection valve 101 of the first embodiment in that they have the same first slit-like injection hole 71 and second slit-like injection hole 72, and the nozzle body tip or needle tip. It differs in points such as the shape of the part. In the following description of the embodiment, the same reference numerals are given to substantially the same components as those in the first embodiment, and the description will be omitted.

(Second Embodiment)
The fuel injection valve according to the second embodiment will be described with reference to FIG. 7A (for a small lift) and FIG. 7B (for a large lift).
As shown in FIGS. 7A and 7B, in the fuel injection valve 102 of the second embodiment, the sack center axis Zs coincides with the body center axis Zb, and the needle center axis Zn is relative to the body center axis Zb. The second slit-shaped injection hole 72 is offset to the inlet 721 side (right side in FIG. 7). As a result, the sack center axis Zs is offset to the opposite side to the inlet 721 of the second slit-shaped nozzle hole 72 with respect to the needle center axis Zn.

The inner wall of the nozzle body 212 is formed in an irregular shape on the left side of FIG. That is, the lower inner wall 221 immediately above the valve seat portion 23 is formed at a symmetrical position with respect to the right inner wall 22 and the body center axis Zb (sack center axis Zs). On the other hand, the upper inner wall 223 above the lower inner wall 221 is formed in a symmetrical position with respect to the opposed right inner wall 22 and the needle center axis Zn, that is, inside the lower inner wall 221. The lower inner wall 221 and the upper inner wall 223 are continuously connected via a slope portion 222.
In addition, a guide portion 38 that can slide in accordance with the diameter between the upper inner wall 223 and the right inner wall 22 is formed at the tip 332 of the needle 302.

  When the valve shown by a broken line in FIG. 7A is closed, the needle 302 is urged downward by the urging force Fd of the spring 18, so that the guide portion 38 extends to the position corresponding to the lower inner wall 221 along the slope portion 222. Go down. Therefore, the seat portion 37 is brought into contact with the valve seat portion 23 in a state where the distal end portion 332 of the needle 302 is guided so as to be coaxial with the body center axis Zb, and the valve is closed.

  When the drive unit 40 is energized and the needle 302 starts to be lifted by the electromagnetic attractive force, the guide unit 38 rises along the slope unit 222, and the central axis of the tip 332 moves from the body central axis Zb to the needle central axis Zn. (By the force Fu shown in FIG. 7A). After that, the center of the tip 332 lifts straight on the needle center axis Zn (FIG. 7B).

At the time of the small lift shown in FIG. 7A, the fuel having a relatively high flow velocity that has passed through the relatively narrow fuel passage 25 between the tip portion 332 of the needle 302 and the valve seat portion 23 of the nozzle body 212 is the sack portion 27. It flows down to the bottom wall 271 in the vicinity of the center of the gas and easily flows into the first slit-shaped nozzle hole 71. At this time, in the right fuel flow FLd in which the fuel passage 25 is narrower than the left fuel flow FLc, direct inflow to the second slit-like injection hole 72 is particularly restricted.
That is, at the time of a small lift, the flow into the first slit-shaped nozzle hole 71 has priority over the flow into the second slit-shaped nozzle hole 72. Therefore, the average surface JL of the spray SL at the time of the small lift is closer to the upper side than the virtual center plane Jo.

On the other hand, at the time of the large lift shown in FIG. 7B, the fuel having a relatively low flow velocity that has passed through the relatively wide fuel passage 25 flows down along the inner wall 272 of the sack portion 27. Then, on the right side of FIG. 7, the ratio of the fuel flowing into the second slit-shaped injection hole 72 in the fuel flow FHd flowing down along the inner wall 272 relatively increases. Further, part of the fuel that has passed through the inlet of the first slit-shaped nozzle hole 71 in the bottom wall 271 of the fuel flow FHc that has flowed down the left inner wall 272 also flows into the second slit-shaped nozzle hole 72.
That is, at the time of a large lift, the ratio of the fuel flowing into the second slit-shaped injection hole 72 is relatively increased. Therefore, the average surface JH of the spray SH at the time of a large lift is closer to the lower side than the virtual center plane Jo.

  As described above, the fuel injection valve 102 balances the amount of fuel flowing into the first slit-like nozzle hole 71 and the second slit-like nozzle hole 72 in accordance with the needle lift amount, like the fuel injector 101 of the first embodiment. By changing the direction, the direction of the average surface of the spray can be moved and the spray can be diffused. Moreover, since the exit of the 1st slit-shaped nozzle hole 71 and the exit of the 2nd slit-shaped nozzle hole 72 are formed in the overlapping position, atomization of fuel is accelerated | stimulated by the collision and collapse of the fuel in cavitation. .

(Third embodiment)
A fuel injection valve according to a third embodiment will be described with reference to FIG. 8A (for a small lift) and FIG. 8B (for a large lift).
As shown in FIGS. 8A and 8B, in the fuel injection valve 103 of the third embodiment, the sack center axis Zs of the sack portion 28 of the nozzle body 213 and the needle center axis Zn of the needle 301 coincide with each other. Yes. A step portion 283 is provided on the bottom wall 281 of the sack portion 28.

  The step portion 283 is on the bottom wall 281 of the sack portion 28 on the side opposite to the inlet of the second slit-shaped nozzle hole 72 with respect to the inlet of the first slit-shaped nozzle hole 71 (left side in FIG. 8). It is provided so as to be located on the needle 301 side (upper side in FIG. 8) from the inlet of the cylindrical injection hole 71. The position of the step of the step portion 283 is preferably close to the inlet of the first slit-shaped nozzle hole 71 so that the inlet of the first slit-shaped nozzle hole 71 becomes a “shadow” of the step. Moreover, it is preferable that the level | step difference height of the level | step-difference part 283 is more than the width W (refer FIG. 3) of a slit-like nozzle hole.

At the time of the small lift shown in FIG. 8A, the fuel having a relatively high flow velocity that has passed through the relatively narrow fuel passage 25 between the tip portion 331 of the needle 301 and the valve seat portion 23 of the nozzle body 213 is the sack portion 28. It flows down to the bottom wall 281 in the vicinity of the center of the gas and easily flows into the first slit-shaped nozzle hole 71. At this time, the fuel flow FLe on the left side and the fuel flow FLf on the right side in FIG. 8 are substantially the same.
That is, at the time of a small lift, the flow into the first slit-shaped nozzle hole 71 has priority over the flow into the second slit-shaped nozzle hole 72. Therefore, the average surface JL of the spray SL at the time of the small lift is closer to the upper side than the virtual center plane Jo.

On the other hand, at the time of the large lift shown in FIG. 8B, the fuel having a relatively low flow velocity that has passed through the relatively wide fuel passage 25 flows down along the inner wall 282 of the sack portion 28. Then, on the left side of FIG. 8, the fuel FHe that has flowed from the inner wall 282 to the stepped portion 283 jumps over the inlet of the first slit-shaped injection hole 71 and falls to the right side of the sack center axis Zs. Then, it merges with the right fuel flow FHf and flows into the second slit-shaped injection hole 72.
That is, at the time of a large lift, the ratio of the fuel flowing into the second slit-shaped injection hole 72 is relatively increased. Therefore, the average surface JH of the spray SH at the time of a large lift is closer to the lower side than the virtual center plane Jo.

  Therefore, as in the first and second embodiments, by changing the balance of the amount of fuel flowing into the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72 according to the needle lift amount, the average surface of the spray The direction of the can be moved to spread the spray. Moreover, since the exit of the 1st slit-shaped nozzle hole 71 and the exit of the 2nd slit-shaped nozzle hole 72 are formed in the overlapping position, atomization of fuel is accelerated | stimulated by the collision and collapse of the fuel in cavitation. .

(Other embodiments)
(A) In the first to third embodiments, the two slit-shaped nozzle holes 71 and 72 are provided “so that they are close to each other from the inlet toward the outlet and overlap the outlet”. In addition, the two slit-shaped nozzle holes are “the inlet of the first slit-shaped nozzle hole is formed in the bottom wall of the sack portion, and the inlet of the second slit-shaped nozzle hole is more needle than the inlet of the first slit-shaped nozzle hole. As long as the requirement “formed on the inner side wall of the side sack portion” is satisfied, it can be provided in the following positional relationship.
Although they approach each other from the inlet toward the outlet, the outlets do not overlap (the sprays injected may collide outside the fuel injection valve depending on the angle of the injection hole reference plane and the distance between the outlets).
・ It is almost parallel.
• Move away from the entrance to the exit.

In these cases, although the atomization effect due to the collision of the spray is not so much obtained, the effect of diffusing the spray is obtained by having two slit-shaped injection holes as compared with the conventional technique having only one slit-type injection hole. be able to.
Furthermore, by offsetting the sack center axis Zs and the needle center axis Zn as in the first and second embodiments, or by providing a stepped portion on the bottom wall of the sack part as in the third embodiment. The distribution of the spray from the two slit-shaped nozzle holes can be changed according to the amount of needle lift, and the diffusion can be improved. Note that the configuration for “changing the distribution of spray from the two slit-shaped nozzle holes according to the needle lift amount” is not necessarily required.

  (A) In addition to the first and second slit-shaped nozzle holes, a third or more slit-shaped nozzle hole may be provided. For example, in the first to third embodiments, the third slit-shaped nozzle hole may be provided at an intermediate position between the first slit-shaped nozzle hole 71 and the second slit-shaped nozzle hole 72, or the first You may provide in the needle 301 grade side further from the 2 slit-shaped injection hole 72. FIG. The same applies to the fourth or more slit-shaped nozzle holes. Needless to say, in addition to the first and second slit-shaped nozzle holes, non-slit circular or elliptical nozzle holes may be provided.

(C) The configuration of the fuel injection valve other than the nozzle body tip provided with the slit-shaped injection hole is not limited to the configuration of the first embodiment, and any known configuration of the fuel injection valve is applied. Also good. The fuel injection valve is not limited to a direct injection type gasoline engine, but may be applied to a port injection type gasoline engine, a diesel engine, or the like.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

101-103 ... Fuel injection valve,
11 ・ ・ ・ Housing (valve body),
20 ... Nozzle holder (valve body),
211-213 ... Nozzle body (valve body),
23 ... valve seat,
24 ... fuel passage,
25 ... Fuel passage,
26, 27, 28 ... Suck part,
261-281 ... bottom wall,
262-282 ... inner wall,
273 ... Stand,
283 ... a step,
301, 302 ... Needle,
331, 332... Tip portion,
37 ... sheet portion 71 ... first slit-shaped nozzle hole,
72 ... the second slit-shaped nozzle hole,
711, 721 ... entrance,
712, 722 ... Exit,
Jo: Virtual center plane,
JL ... average surface (at the time of a small lift),
JH ... average surface (at the time of a big lift),
SL ... Spray (at the time of a small lift),
SH ... spray (at the time of small lift),
Zb ... body center axis,
Zn: needle central axis,
Zs ... Sack central axis.

Claims (6)

A fuel passage communicating from one end to the other end in the axial direction, a valve seat portion formed on the inner wall of the fuel passage, a sac portion formed downstream of the valve seat portion in the fuel flow direction and storing fuel, and the sac A valve body having a plurality of slit-shaped nozzle holes communicating the bottom wall or inner wall and the outer wall of the unit;
A needle that is accommodated in the valve body so as to be reciprocally movable in the axial direction, and that shuts off the inflow of fuel to the sac portion when a tip portion contacts the valve seat portion;
With
The plurality of slit-shaped nozzle holes include a first slit-shaped nozzle hole in which an inlet is formed in a bottom wall of the sac portion, and an inner side of the sack portion on the needle side than the inlet of the first slit-shaped nozzle hole Including a second slit-shaped nozzle hole in which an entrance is formed in the wall;
The first slit-shaped nozzle hole and the second slit-shaped nozzle hole are inclined from the inlet toward the outlet toward the side on which the inlet of the second slit-shaped nozzle is formed with respect to the central axis of the valve body. The fuel injection valve characterized by the above-mentioned. The sack central axis that is the central axis of the sac portion is offset to the opposite side of the inlet of the second slit-shaped nozzle hole with respect to the needle central axis that is the central axis of the needle,
The first slit-shaped nozzle hole and the second slit-shaped nozzle hole from the fuel passage according to a change in the needle lift amount from the state where the tip of the needle is in contact with the valve seat to the fully opened state. The fuel injection valve according to claim 1, wherein the balance of the amount of fuel flowing into the fuel changes.   The fuel injection valve according to claim 2, wherein the needle central axis coincides with the central axis of the valve body, and the sack central axis is offset with respect to the central axis of the valve body. The valve body is
A base portion is provided at the boundary portion between the valve seat portion and the sac portion opposite to the offset side of the sack center axis so as to narrow the width of the fuel passage between the needle tip portion. The fuel injection valve according to claim 3. The valve body is
A step located on the bottom wall of the sac portion on the opposite side of the inlet of the second slit-shaped nozzle hole from the inlet of the first slit-shaped nozzle hole and located closer to the needle side than the inlet of the first slit-shaped nozzle hole Part is provided,
The first slit-shaped nozzle hole and the second slit-shaped nozzle hole from the fuel passage according to a change in the needle lift amount from the state where the tip of the needle is in contact with the valve seat to the fully opened state. The fuel injection valve according to claim 1, wherein the balance of the amount of fuel flowing into the fuel changes. The angle of the first slit-shaped nozzle hole with respect to the central axis of the valve body is formed relatively larger than the angle of the second slit-shaped nozzle hole with respect to the central axis of the valve body,
The fuel injection valve according to any one of claims 1 to 5, wherein an outlet of the first slit-shaped nozzle hole and an outlet of the second slit-shaped nozzle hole are formed at overlapping positions. .

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