JP4548448B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that is mounted on an internal combustion engine and injects fuel into the internal combustion engine, and more particularly to a fuel injection valve that has a function of preventing deposits from depositing around the injection hole for injecting fuel. It is.

In a fuel injection valve used for a gasoline direct injection engine or the like, a nozzle hole provided at the tip of the fuel injection valve is exposed to a high temperature environment in an engine combustion chamber.
For this reason, it is known that fuel-derived carbides and the like are deposited on the surface of the nozzle hole as deposits, which clog the nozzle hole, causing a decrease in fuel injection amount and abnormal spray shape. It has become.

  Conventionally, as a technique for solving such a problem, Patent Document 1 discloses that a countersink groove is provided on the tip side of an injection nozzle, and deposits around the injection port when a part of the fuel injected from the injection port returns. Techniques for preventing the formation of

In recent years, from the viewpoints of improving fuel consumption and reducing emissions in combustion exhaust, fuel injection valves used in direct injection engines have been required to further atomize injected fuel and perform highly accurate fuel injection control.
Therefore, for such a demand, a fuel injection valve 1X as shown in FIG. 7 is used. In the fuel injection valve 1X, an injection hole plate 110X fixed at the tip of the fuel injection portion 10X is injected into the injection hole plate 110X. A plurality of extremely small nozzle holes 111 having a hole diameter of about 100 μm are formed on a virtual circle.
Further, in a direct injection engine, fuel is injected in a state where the air-fuel mixture in the internal combustion engine is compressed to a high pressure.
JP-A-11-82229

However, around the high-pressure jet of the fuel 400 injected at an extremely high pressure from the extremely small nozzle hole 111X, as shown in FIG. 8A, a vortex is generated and the surrounding gas is drawn near the nozzle hole 111X. It is out.
Further, in the combustion chamber of the internal combustion engine, not only the fuel mixture 41 but also a siloxy acid (—Si—O—) compound used as an antifoaming agent in the lubricating oil of the internal combustion engine, and a trace amount in the fuel are contained. Impurities 42 such as metals and unburned carbides are floating.
For this reason, some of the fuel particles 41 injected from the nozzle holes 111X and the impurities 42 are directed to the surface of the nozzle hole plate 110X by the vortex generated around the high-pressure jet, and adhere to the surface of the nozzle plate 110X.
Due to the combustion of the internal combustion engine, the surface of the nozzle hole plate 110 </ b> X receives heat of several hundred degrees Celsius, and the fuel particles 41 and the impurities 42 are combined to form an amorphous deposit 40.
The thermal decomposition product of siloxy acid contained in the deposit 40 has a lower melting point due to bonding with a metal such as zinc in the impurity 42, and the fluidity of the deposit 40 is increased.

  For this reason, as shown in FIG. 8 (b), the vortex generated around the injected fuel or the deposit 40 deposited on the surface of the nozzle hole plate 110X by the air flow generated during compression gradually attracts the vicinity of the nozzle hole 111. Eventually, the nozzle hole 111 may be clogged.

  In view of the above circumstances, the present invention suppresses the movement of deposit inevitably deposited on the surface of the nozzle hole plate provided at the tip of the fuel injection valve to the vicinity of the nozzle hole, and prevents the nozzle hole from being clogged. It aims at providing the injection valve which can maintain this.

According to the first aspect of the present invention, a valve body mounted on the internal combustion engine and having a fuel flow path formed therein, and fuel that is disposed downstream of the fuel flow path in the valve body and flows out of the fuel flow path In a fuel injection valve having an injection hole plate having injection holes, the injection hole plate is divided into a central region and an injection hole forming region in which a plurality of injection holes are formed around the central region. A concave portion having a substantially arc-shaped cross section is formed by recessing the surface of the nozzle hole plate in the central region toward the base end side .

According to the first aspect of the present invention, the deposit is formed on the surface of the nozzle hole plate by the deposit component existing in the internal combustion engine, and flows by the air flow generated toward the nozzle hole when fuel is injected from the nozzle hole. Can be retained in the recess.
For this reason, even if the airflow which goes to a nozzle hole direction generate | occur | produces at the time of fuel injection, a deposit does not move to a nozzle hole vicinity, but can prevent entering a nozzle hole.
Accordingly, it is possible to realize a highly reliable fuel injection valve that hardly causes clogging of the injection hole.

As another aspect of the invention of claim 2, as another means for retaining the deposit outside the nozzle hole forming region, the nozzle hole plate is formed with a central region and a plurality of nozzle holes around the central region. a nozzle hole forming region, is divided into an outer peripheral region of the nozzle hole forming region, a said injection hole plate surface, and the boundary portion and the nozzle hole formation area of the nozzle hole formation region and the central region You may form the cyclic | annular convex part which the boundary part with the said peripheral area | region protrudes cyclically | annularly toward a fuel injection direction.

According to the invention of claim 2, since the deposit does not move to the vicinity of the injection hole beyond the annular convex portion, the deposit can be stopped in the central region and the peripheral region.
Accordingly, it is possible to realize a highly reliable fuel injection valve that hardly causes clogging of the injection hole.

  As another aspect of the invention of claim 3, as another means for retaining the deposit outside the nozzle hole forming region, the nozzle hole plate is formed with a central region and a plurality of nozzle holes around the central region. It is divided into a nozzle hole forming region and a peripheral region outside the nozzle hole forming region, and the boundary portion between the nozzle hole opening edge and the nozzle hole forming region is the surface of the nozzle hole plate. You may form the cylindrical convex part which protrudes in a cylinder shape toward the fuel injection direction over the perimeter of an edge.

According to invention of Claim 3, a deposit does not penetrate | invade into a nozzle hole exceeding the cylindrical convex part protrudingly provided by the nozzle hole opening edge.
Accordingly, it is possible to realize a highly reliable fuel injection valve that hardly causes clogging of the injection hole.

  According to a fourth aspect of the present invention, a valve body that is mounted on an internal combustion engine and has a fuel flow path formed therein, and fuel that is disposed downstream of the fuel flow path of the valve body and flows out of the fuel flow path, is provided. In a fuel injection valve having an injection hole plate having injection holes, the injection hole plate is divided into a central region and an injection hole forming region in which a plurality of injection holes are formed around the central region. A central nozzle hole that forms a fuel jet that is formed in the central region and that generates an air flow around the fuel jet that is injected from the nozzle hole formed in the nozzle hole forming region. It comprises.

According to invention of Claim 5, it forms around the fuel flow injected from the airflow formed around the fuel jet injected from the center nozzle hole, and the nozzle hole formed in the said nozzle hole formation area | region. The airflow is offset and no airflow toward the nozzle hole is generated.
Therefore, even if the deposit is formed in the central region, the deposit does not move near the nozzle hole and can be prevented from entering the nozzle hole.
In addition, the fuel injection from the central injection hole prevents the component that generates deposits from adhering to the surface of the central region.
Accordingly, it is possible to realize a highly reliable fuel injection valve that hardly causes clogging of the injection hole.

The structure of the fuel injection valve 1 as a fuel injection valve that is the basis of the present invention will be described with reference to FIG.
In the following description, the upper side of the figure is the base end side, and the lower side is the front end side or the injection side.
The fuel injection valve 1 is, for example, attached to an unillustrated intake port when used as a fuel injection valve for a premixed engine, and an unillustrated engine when used as a fuel injection valve for a direct injection engine. When mounted on the head and used as a fuel injection valve for a rich spike, it is mounted on an exhaust port (not shown).

The fuel injection valve 1 includes a fuel injection unit 10, a drive unit 20, and a fuel introduction unit 30.
The fuel injection unit 10 includes a cylindrical valve body 130, a valve body 120 placed so as to be movable in the axial direction within the valve body 130, and an injection hole plate 110 fixed to the tip of the valve body 130 by a holder 140. And is composed of.

The nozzle hole plate 110 has a plurality of nozzle holes 111 formed at equal intervals on a virtual circle.
Further, the injection direction of each nozzle hole 111 is set in consideration of the spray shape corresponding to the internal combustion engine to be mounted.
As a means for retaining deposits in the central area AR1, a concave portion 112 that is depressed toward the proximal end is formed on the distal surface of the nozzle hole plate 110, which is the main part of the present invention.

  The valve body 130 has a valve body bottom 131 that is bent toward the center of the shaft while opening the tip, and a conical valve seat 132 having a diameter that decreases toward the tip. Is formed.

A fuel flow path 125 through which fuel flows is formed in the gap between the valve body 120 and the inner peripheral wall of the valve body 130.
A sliding portion 123 is formed on the distal end side of the valve body 120 so as to allow the fuel flow path 125 and the valve body 130 opening to communicate with each other while the valve body 120 is slidably supported in the valve body 130. A contact portion 122 that can be seated on the valve seat portion 132 of the valve body 130 is formed at the distal end portion 121 of the valve body on the distal end side.
A proximal end portion 124 is formed on the proximal end side of the valve body 120 and is connected to the movable core 200.

The drive unit 20 includes a cylindrical casing 240, a cylindrical fixed core 210 fixed to the base end side in the casing 240, a cylindrical movable core 200 slidably housed in the casing 240, A cylindrical stopper 220 fixed on the base end side in the fixed core 210, and a coil spring 230 provided between the movable core 200 and the stopper 220 and biasing the movable core 200 in the anti-fixed core direction, that is, the valve closing direction. A solenoid 260 wound around the casing 240, a cylindrical spool 250 that isolates the solenoid 260 and the casing 240, a terminal 261 conducting to the solenoid 260, and a connector covering the spool 250 and the solenoid 260. It is comprised with the mold 270 which forms the part 271.
The distal end of the casing 240 is inserted into a cylindrical housing portion 142 formed on the proximal end side of the holder 140.
A fuel flow path 202 is formed on the inner peripheral side of the movable core 200, and a communication hole 201 is formed to communicate the fuel flow path 202 with the outer periphery.

  The fuel introduction unit 30 includes a cylindrical filter body 310 formed with a fuel introduction port 311 for introducing high-pressure fuel from the outside, and a filter 312 for removing foreign matter in the high-pressure fuel. It is inserted.

The high-pressure fuel introduced from the fuel inlet 311 via the filter 312 passes through the fuel flow path 211 formed on the inner peripheral side of the fixed core 210 and the fuel flow path 221 formed on the inner peripheral side of the stopper 220. Then, the fuel flows into the fuel flow path 202 formed on the inner peripheral side of the movable core 200.
The high-pressure fuel 400 in the fuel flow path 202 presses the back surface of the base end portion 124 of the valve body 120 in the seating direction, passes through the communication hole 201, and the fuel flow path 241 formed on the inner peripheral side of the casing 240. Then, the fuel flows into the fuel flow path 125 formed on the inner peripheral side of the valve body 130 via the casing opening 242 and the fuel flow path 144 formed on the inner peripheral side of the holder 140.

  When the solenoid 260 is not energized, the back surface of the base end portion 124 is pressed by the high-pressure fuel, and the valve body 120 is urged by the coil spring 230 and is pushed down toward the distal end side, that is, the anti-fixed core. The portion 121 is seated on the valve seat 132 and blocks the high pressure fuel 400 introduced into the fuel flow path 125 from flowing out of the fuel flow path 125.

When a pulse voltage controlled by an unillustrated ECU is energized to the solenoid 260 via the terminal 261, the fixed core 210 is excited and the movable core 200 is attracted to the fixed core 210 side.
Along with this, the valve body 120 is pulled up toward the base end side, that is, the fixed core 210, and the contact portion 121 is separated from the valve seat 132.
When the contact portion 121 moves away from the valve seat 132, the high pressure fuel 400 in the fuel flow path 125 passes through the opening of the valve body 130 and is injected from the plurality of injection holes 111 formed in the injection hole plate 110. .

  When the energization of the solenoid 260 is stopped, the fixed core 210 is demagnetized, and the movable core 200 and the valve body 120 are pushed down to the front end side by the pressure of the high-pressure fuel in the fuel flow path 202 and the coil spring 230, and again The contact portion 122 is seated on the valve seat 132, the flow of the high-pressure fuel 400 from the fuel flow path 125 to the nozzle hole plate 110 is shut off, and the fuel injection is stopped.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
The basic configuration is the same as that of the fuel injection valve 1 described above, and substantially the same configuration is denoted by the same reference numeral, and therefore the description thereof is omitted. Only the characteristic items in each embodiment will be described in detail.

Referring to FIG. 2, detailed description is given of concave portion 112 as means for retaining deposits in central region AR1 of nozzle plate 110 and nozzle plate 110, which is the main part of the present invention in the first embodiment of the present invention. To do.
FIG. 2A is an enlarged cross-sectional view showing a main part of the fuel injection unit 10 according to the first embodiment of the present invention, and FIG. 2B is a plan view taken along the line AA in FIG.
The fuel injection unit 10 includes a cylindrical valve body 130 having a fuel flow path 125 formed therein, and an injection hole 111 that is disposed on the downstream side of the valve body 130 and injects fuel flowing out of the fuel flow path 125. The injection hole plate 110, the cylindrical holder 140 that holds the valve body 130 and the injection hole plate 110 inside, and the valve body contact portion 122 is seated on the valve seat 133 formed on the inner peripheral wall of the valve body 130. And the valve body 120 that closes the fuel flow path 125 and opens the fuel flow path 125 when the valve body abutting portion 122 is separated from the valve seat 133.

As shown in FIG. 2B, the nozzle hole plate 110 is divided into a central area AR1, a nozzle hole forming area AR2 in which a plurality of nozzle holes 111 are formed, and a peripheral area AR3 outside thereof. It is partitioned.
In the present embodiment, in the central area AR1 of the surface of the nozzle hole plate 110, the concave portion 112 in which the surface of the nozzle hole plate 110 is recessed toward the proximal end is formed in a substantially circular shape over substantially the entire area. Yes.
By providing such a recessed portion 112, the surface of the injection hole forming area AR2 including the injection side opening edge of the injection hole 111 is relatively higher toward the tip side than the surface of the central area AR1.
In this embodiment, recess 112, that form a cross section in a substantially arcuate concave shape.

The effect when the fuel injection valve 1 according to the first embodiment of the present invention is mounted on the engine head of a direct injection engine (not shown) will be described with reference to FIG.
As shown in FIG. 3A, when the valve body 120 is separated from the valve body 130, the fuel 400 accumulated at a high pressure is injected into the internal combustion engine from the injection holes 111 as mist-like fuel particles 41. .
A vortex is generated around the fuel jet injected at an extremely high injection pressure.
Part of the fuel particles 41 injected into the internal combustion engine and the impurities 42 floating in the internal combustion engine are carried to the surface of the nozzle hole plate 110 by this vortex.
At this time, the fuel particles 41 and the impurities 42 are collected in a recessed portion 112 formed in a state where the fuel particles 41 and the impurities 42 are recessed toward the base end side on the surface of the nozzle hole plate 110.
Due to the combustion of the internal combustion engine, the surface of the nozzle hole plate 110 receives heat of several hundred degrees Celsius, and the fuel particles 41 and the impurities 42 are combined to form an amorphous deposit 40.
However, as shown in FIG. 3 (b), the deposit 40 is confined in the recess 112, so that the deposit 40 does not move to the vicinity of the injection hole 111 due to the vortex flow during fuel injection or the air flow during compression. There is no blockage.

Here, the formation process of the deposit 40 when the conventional fuel injection valve 1X is used in a direct injection engine (not shown) will be described in detail with reference to FIG. 9, FIG. 10, and FIG.
FIG. 9 shows the result of observing the deposit formed on the surface of the nozzle hole plate 110X with a laser microscope after the endurance test for 6 hours after mounting the fuel injection valve 1X in the center of the engine head of the direct injection engine. 10 is an enlarged photograph of a portion surrounded by a white frame in FIG. 9, and FIG. 11 is a schematic cross-sectional view showing a surface profile at AB in FIG.
Eight nozzle holes 111 are formed in the nozzle hole plate 110X at equal intervals on a virtual circle.
The air-fuel mixture in the combustion chamber contains unburned carbon produced by incomplete combustion of hydrocarbons supplied as fuel, siloxy acid (-Si-O-) added as an antifoaming agent for engine oil, Zinc and the like contained in a very small amount are contained, and this is combined with residual fuel after fuel injection, and forms a fluid deposit on the surface of the nozzle hole plate 110X by receiving heat from a high temperature environment.

As shown in FIGS. 10 and 11, the deposit is deposited so as to stand in the vertical direction with respect to the surface of the nozzle hole plate 110 </ b> X at the center of the nozzle hole plate 110 </ b> X.
In addition, a deposit standing upright in a direction perpendicular to the surface of the nozzle hole plate 110X can be observed outside the nozzle hole 111.
Aligned deposit particles exist between the standing deposit and the nozzle hole 111, and streaks that are seen as jet marks are formed radially from the nozzle hole 111 around the nozzle hole 111.
Furthermore, no deposit was formed inside the nozzle hole 111 and around the opening edge, and the deposits that moved from the inside and outside of the nozzle hole 111 collided and rose between the two nozzle holes. A portion where the deposited deposit is thickly observed can be observed.

  For these reasons, the clogging of the nozzle hole 111 due to the deposit is not caused by the injected fuel remaining in the nozzle hole 111, but the deposit deposited around the center of the nozzle hole plate 110 </ b> X and the outer periphery of the nozzle hole 111 has a high pressure. It is presumed that the airflow generated around the jet flow or the airflow generated at the time of compression gradually approaches the nozzle hole 111 and is eventually pushed into the nozzle hole 111.

  The present invention has been conceived based on such knowledge, and according to the present invention, deposits on the surface of the nozzle hole plate are brought close to the nozzle holes by airflow generated during fuel injection, airflow generated during compression and combustion, and the like. It is expected to provide a fuel injection valve that suppresses movement and is less likely to clog the nozzle hole.

A reference example will be described with reference to FIG .
This reference example is different from the first embodiment of the present invention only in the nozzle hole plate 110, and the other parts are the same as those in the first embodiment described above, so the description is omitted . Only the features of this reference example will be described. (The same applies to the following embodiments.)
As shown in FIG. 4A, a pipe-shaped member longer than the thickness of the nozzle hole plate 110a is inserted inside the nozzle hole 111a, and the boundary between the opening edge of the nozzle hole 111a and the nozzle hole forming region AR2 Ru was projecting cylindrical protrusion 114 which bulge toward the fuel injection direction tare.

Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 5A is a cross-sectional view of the main part in the present embodiment, and FIG.
In this embodiment, as shown in FIGS. 5 (a) and 5 (b), as the deposit retaining means, the boundary between the nozzle hole forming area AR2 and the central area AR1, the nozzle hole forming area AR2, and the outer periphery thereof. At the boundary with the area AR3, annular protrusions 114b that protrude in the fuel injection direction are provided so as to protrude from the surface of the nozzle hole plate.
With this configuration, the convex portion 114 becomes a barrier, deposits formed on the surface of the injection hole plate 110b outside the inner annular projection 114b and the annular convex portion 114b is, and fuel injection by compression It can suppress approaching the vicinity of the nozzle hole 111 by the generated airflow.

Furthermore, another reference example will be described with reference to FIG.
FIG 6 (a), (b) is a fragmentary cross-sectional view of the present embodiment.
As shown in FIG. 6A, in this reference example , in addition to the plurality of injection holes 111 formed in the injection hole formation region AR2, the injection hole plate 110c has a central injection hole in the central region AR1. 115 is formed.
In general, the inner diameter of the injection hole 111 is set so as to achieve fuel injection that meets the combustion conditions of the applied internal combustion engine.
In addition to this, in the present reference example , the air flow generated by the fuel injection from the injection hole 111 and the air flow generated by the fuel injection from the central injection hole 115 cancel each other out in the injection hole formation region AR2. The inner diameter of the injection hole 111 and the central injection hole 115 are set so that the sum of the injection quantity from the formed injection hole 111 and the injection quantity from the central injection hole 115 formed in the center region AR1 are substantially the same. The inner diameter is set.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
For example, in the first embodiment of the present invention, the concave portion 112 is provided as the deposit retaining means in the central region AR1 of the nozzle hole plate 110. In addition, the surface of the peripheral region AR3 faces the base end side. An annular recess that is recessed may be provided.
In this way, it is possible to prevent the deposit moving from the peripheral area AR3 toward the nozzle hole 111 from entering the nozzle hole 111.
Similarly, in the reference example , the central injection hole 115 is provided in the central region AR1, but in addition to this, as a means for retaining the deposit in the peripheral region AR3, the surface of the peripheral region AR3 is directed toward the base end side. A recessed annular recess may be provided, or an annular protrusion that protrudes in the fuel injection direction may be provided at the boundary between the nozzle hole formation region AR2 and the peripheral region AR3.

In the above-described embodiment, the case where the solenoid is used as the drive source of the valve body has been described. However, a piezo stack that expands and contracts by energization may be used as the drive source of the valve body.
Furthermore, the number of nozzle holes drilled in the nozzle hole plate is not limited to the number shown in the above embodiment, and the present invention includes a nozzle plate in which two or more nozzle holes are drilled. It is suitable for a fuel injection valve.
In addition, the present invention is particularly suitable for a fuel injection valve in a direct injection engine. However, the present invention is not limited to a fuel injection valve for a direct injection engine, but also for a fuel injection valve provided in an intake port or an exhaust port. It can be applied.

Sectional drawing which shows the whole structure of the fuel injection valve used as the foundation in embodiment of this invention. (A) is a principal part expanded sectional view in the 1st Embodiment of this invention, (b) is an AA arrow top view in this figure. (A) is a principal part expanded sectional view at the time of the fuel injection in the 1st Embodiment of this invention, (b) is a schematic diagram which shows the effect. (A) , (b) is an important section expanded sectional view in a reference example . (A) is a principal part expanded sectional view in the 2nd Embodiment of this invention, (b) is an AA arrow top view in this figure. (A) , (b) is principal part sectional drawing in a reference example . Sectional drawing which shows the whole structure of the conventional fuel injection valve. (A) is a principal part expanded sectional view which shows the mode of the production | generation of the deposit in the conventional fuel injection valve, (b) is a principal part expanded sectional view which shows the mode of the movement of a deposit. The laser micrograph which shows the surface of the nozzle hole plate in which the deposit in the conventional fuel injection valve was formed. FIG. 10 is an enlarged laser micrograph of a white frame surrounded part in FIG. 9. Sectional schematic diagram which shows the outline | summary of the surface profile in AB in FIG.

Explanation of symbols

1 Fuel injection valve (fuel injection valve)
DESCRIPTION OF SYMBOLS 10 Fuel injection part 110 Injection hole plate 111 Injection hole 112 Recessed part 114 Cylindrical convex part 114b Annular convex part 115 Central injection hole 120 Valve body 122 Valve body contact part 125 Fuel flow path 131 Valve body 132 Valve seat AR1 Central area AR1
AR2 injection hole formation area AR3 peripheral area

Claims (2)

A valve body mounted on an internal combustion engine and having a fuel flow path formed therein, and an injection hole disposed on the downstream side of the fuel flow path in the valve body for injecting fuel flowing out of the fuel flow path In a fuel injection valve comprising a hole plate,
The nozzle hole plate is divided into a central region and a nozzle hole forming region in which a plurality of nozzle holes are formed around the central region,
A fuel injection valve characterized in that a cross-section in which the surface of the nozzle hole plate in the central region is recessed toward the proximal end forms a substantially arcuate recess. A valve body mounted on an internal combustion engine and having a fuel flow path formed therein, and an injection hole disposed on the downstream side of the fuel flow path in the valve body for injecting fuel flowing out of the fuel flow path In a fuel injection valve comprising a hole plate,
Dividing the nozzle hole plate into a central region, a nozzle hole forming region in which a plurality of nozzle holes are formed around the central region, and a peripheral region outside the nozzle hole forming region;
A said injection hole plate surface, annular projection the boundary portion between the boundary portion and the nozzle hole forming region and the peripheral region between the nozzle hole formation region and the central region is raised toward the fuel injection direction in a ring The fuel injection valve characterized by forming.