JP2008255836A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device in which deposit is hard to generate in a nozzle hole formed at the end thereof. <P>SOLUTION: This fuel injection device 1 comprises: a cylindrical holder 140 for internally holding a cylindrical valve body 130 having a fuel flow passage 125 and a valve seat 133 and a nozzle hole plate 11 disposed on the downstream side of the valve body 130 and jetting the fuel flowing out of the fuel flow passage 125 into an internal combustion engine; and a valve element 120 for opening and closing the fuel flow passage 125 by leaving and sitting on the valve seat 133. The nozzle hole plate 11 is formed of a plate member 110 having a plurality of flat surface layers containing an inflow side flat surface layer 110a and a jetting side flat surface layer 110b ranging from the inflow side toward the jetting side. The inflow side flat surface layer 110a and the jetting side flat surface layer 11b are formed of the members having different coefficients of linear expansion, respectively. The nozzle hole plate 11 is curved when receiving heat from the internal combustion engine, and the deposit formed on the inner peripheral wall surface of the nozzle hole 111 is peeled off. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection device that is mounted on an internal combustion engine and injects fuel.

In recent years, fuel injection devices have been required to atomize fuel to be injected and to control fuel injection with extremely high accuracy.
In Patent Document 1, as such a fuel injection device, fuel that has passed through a fuel flow path constituted by a valve body and a valve member is injected through an injection hole formed in an injection hole plate. In the apparatus, a technique is disclosed in which a step portion is provided in the nozzle hole plate to control the jet flow to further atomize the injected fuel.

  In addition, from the viewpoint of reducing environmental impact, in order to improve fuel economy and reduce harmful substances in exhaust gas, fuel injection is performed in the intake port where the exhaust gas that has been compressed and heated is recirculated, and the combustion chamber The fuel is directly injected into the exhaust port, or a very small amount of fuel is injected into the exhaust port, and the exhaust gas purification catalyst performs a rich spike that suppresses the generation of NOx.

However, in the usage environment of these fuel injection devices, the fuel injection device is used in a high temperature environment such as a compressed air-fuel mixture in the intake port, heat generated by combustion explosion in the combustion chamber, or high temperature exhaust in the exhaust port. The nozzle hole is exposed for a long time.
For this reason, a small amount of fuel remaining on the surface of the nozzle hole after fuel injection is carbonized by receiving heat from a high temperature environment and gradually accumulates as a deposit on the surface of the nozzle hole.

  In Patent Document 2, the temperature of the nozzle of the fuel injection valve is maintained lower than the 90% distillation temperature of the fuel, and the deposit precursor in the fuel is dispersed and held in the liquid phase state, so that the deposit precursor is injected into the fuel. A technique for efficiently and accurately removing outflow from the nozzle by flow is disclosed.

In Patent Document 3, a coating layer made of an oil-repellent material is formed on the inner wall forming the nozzle hole of the fuel injection nozzle and the nozzle tip surface continuous to the inner wall, making it difficult for the fuel component to adhere to the nozzle tip. There has been disclosed a technique for suppressing the formation of deposit by facilitating separation of the adhering fuel component by the next fuel injection.
Japanese Patent Laid-Open No. 2004-21682 JP-A-9-264232 Japanese Patent Laid-Open No. 11-2392

However, in recent years, in order to further improve the injection accuracy, the injection hole formed in the injection hole plate used in the fuel injection device is required to have extremely high accuracy, and it is caused by the fuel remaining slightly on the inner peripheral wall surface of the injection hole. Removal of minute deposits inevitably formed is an important issue.
For example, the nozzle hole plate 11X shown in FIG. 9 is made of a plate member formed in a disk shape having an outer diameter φD ₁ X of φ5 mm and a plate thickness T of 300 μm. A plurality of injection holes 111X are formed on an imaginary circle φD ₂ X concentric with the shaft at an angle θ that spreads from the fuel inflow side toward the fuel injection side.
The virtual circle φD ₂ X is 3.0 mm, the nozzle hole drilling angle θ is 30 °, and the inner diameter of the nozzle hole 111X is φ100 μm.
In the drawing, a cross section of two nozzle holes 111X out of eight nozzle holes 111X drilled at a substantially equal pitch is shown.

When such an injection hole plate 11X is used in the fuel injection device, a very small amount of the fuel injected from the injection hole 111 inevitably remains in a thin film shape.
This receives heat from the internal combustion engine and carbonizes and gradually accumulates, and a deposit 40 is formed on the surface of the injection hole 111X and the surface on the injection hole plate 11X injection side.
The thickness of the deposit 40 is about 1 to 10 μm on the inner peripheral wall surface of the injection hole 111X, and about 1 to 30 μm on the injection side surface of the injection hole plate 11X.
Even if such a very small amount of deposit is formed on the inner peripheral wall surface of the injection hole of the fuel injection device, once it is formed, it may cause further accumulation of deposit, which may cause a decrease in the fuel injection amount and an abnormality in the spray shape. .

  In view of the above circumstances, the present invention provides a highly reliable fuel injection device in which deposits are difficult to accumulate on the surface of the injection hole provided at the tip of the fuel injection device.

According to the first aspect of the present invention, a cylindrical valve body mounted on the internal combustion engine and having a fuel flow path formed therein, and disposed on the downstream side of the valve body, the fuel flowing out from the fuel flow path is injected. A nozzle hole plate having a nozzle hole, a cylindrical holder for holding the valve body and the nozzle hole plate on the inside thereof, and a valve body contact portion, the valve body contact portion being an inner part of the valve body; A valve body that closes the fuel flow path by being seated on a valve seat formed on a peripheral wall and opens the fuel flow path when the valve body abutting portion is separated from the valve seat. In the fuel injection device,
The nozzle hole plate is configured by a plurality of plane layers including an inflow side plane layer and an ejection side plane layer from an inflow side into which the fuel flows in to an ejection side from which the fuel is ejected. The ejection side plane layer is formed of a member having a different linear thermal expansion coefficient.

According to the first aspect of the present invention, in order to retain heat of the nozzle hole plate, each plane layer expands to a different size due to a difference in thermal expansion coefficient of each plane layer. The inner peripheral wall is curved or the inner peripheral wall surface is displaced.
This bending or misalignment generates a shearing force that acts on the deposit formed on the surface of the nozzle hole in the direction of peeling the deposit from the surface of the nozzle hole.
Further, when the nozzle hole plate is not receiving heat, the curve of the inner peripheral wall of the nozzle hole or the positional deviation of the inner peripheral wall surface is restored.
The nozzle hole plate repeatedly expands and contracts by heat receiving and non-heat receiving depending on the state of the internal combustion engine, and shear force in the direction in which the deposit peels repeatedly acts on the inner peripheral wall surface of the nozzle hole.
Therefore, the deposit inevitably formed on the inner peripheral wall surface of the nozzle hole can be peeled from the surface of the nozzle hole, the accumulation of the deposit is suppressed, and there is no risk of causing a decrease in the fuel injection amount or an abnormality in the spray shape. Equipment can be provided.

  In the invention of claim 2, the inflow side plane layer and the ejection side plane layer are configured by laminating different individual plate-like members.

According to the second aspect of the present invention, when receiving heat from the internal combustion engine, the plate member having a larger linear thermal expansion coefficient than that of the plate member having a smaller linear thermal expansion coefficient is extended. The surface is displaced, and deposits formed on the inner peripheral wall surface of the nozzle hole are peeled off from the inner peripheral wall surface of the nozzle hole.
Therefore, the deposit inevitably formed on the inner peripheral wall surface of the nozzle hole can be peeled off from the nozzle hole surface, the accumulation of the deposit is suppressed, and there is no possibility of causing a decrease in the fuel injection amount or an abnormal spray shape. A device can be realized.

  According to a third aspect of the present invention, the inflow side plane layer and the ejection side plane layer are joined so that the surfaces of the opposing layers are fixed to each other over the entire surface.

In the third aspect of the invention, in order to retain heat from the internal combustion engine, either the inflow side plane layer or the ejection side plane layer, whichever has the higher linear thermal expansion coefficient, extends well. The nozzle hole plate is curved so as to be convex toward the side with the larger coefficient of thermal expansion, and the inner peripheral wall of the nozzle hole is also curved accordingly, and is restored to a plate shape when not receiving heat.
By repeating the heat receiving and non-heat receiving of the nozzle hole plate, the nozzle hole plate repeatedly curves and recovers, and the inner peripheral wall of the nozzle hole also curves and recovers accordingly.
Therefore, the fuel injection device that can peel the deposit formed on the inner peripheral wall surface of the nozzle hole from the surface of the inner peripheral wall of the nozzle hole, suppress the accumulation of the deposit, and does not cause a decrease in the fuel injection amount or an abnormality in the spray shape. Can be realized.

  In the invention of claim 4, the inflow side plane layer and the ejection side plane layer use a powder material having two or more different linear thermal expansion coefficients and are mixed so that the blending ratio differs depending on the layer. Formed by.

According to the fourth aspect of the present invention, it is possible to form a completely integrated nozzle hole plate while the inflow side plane layer and the ejection side plane layer have different linear thermal expansion coefficients.
In order to retain heat from the internal combustion engine, one of the inflow side plane layer and the ejection side plane layer, which has a large linear thermal expansion coefficient, is well extended. The nozzle hole plate is curved so as to be convex, and the inner peripheral wall of the nozzle hole is also curved accordingly, and is restored to a plate shape when not receiving heat.
Therefore, the fuel injection device that can peel the deposit formed on the inner peripheral wall surface of the nozzle hole from the surface of the inner peripheral wall of the nozzle hole, suppress the accumulation of the deposit, and does not cause a decrease in the fuel injection amount or an abnormality in the spray shape. Can be realized.

  In the invention of claim 5, the inflow side plane layer and the ejection side plane layer fix the outer peripheral edge thereof to the inner peripheral edge of the holder.

According to the invention of claim 5, in addition to the effect of suppressing the accumulation of deposits, the center axis of the injection hole formed in each planar layer is shifted when the expansion and contraction is repeated between the time of receiving heat and the time of not receiving heat. Therefore, stable fuel injection can be realized.
Therefore, the reliability as a fuel injection device is further improved.

  In the invention of claim 6, the inflow side plane layer and the ejection side plane layer are formed of a member having a larger linear thermal expansion coefficient than the holder.

When receiving heat, not only the nozzle hole plate but also the holder is thermally expanded. If the holder has a linear thermal expansion coefficient larger than that of the nozzle hole plate, the holder extends beyond the nozzle hole plate. It is pulled and inhibits the curvature of the inner peripheral wall of the nozzle hole, and the effect of the present invention is halved.
According to the invention of claim 8, at the time of heat reception, the holder restrains the radial expansion of the nozzle hole plate, and the nozzle hole plate is surely curved in the axial direction.
Therefore, the fuel injection device that can peel the deposit formed on the inner peripheral wall surface of the nozzle hole from the surface of the inner peripheral wall of the nozzle hole, suppress the accumulation of the deposit, and does not cause a decrease in the fuel injection amount or an abnormality in the spray shape. Can be realized.

  In the invention according to claim 7, of the plurality of planar layers, only the outer peripheral edge of the planar layer having the smallest linear expansion coefficient and the inner peripheral edge of the holder are fixed to each other, and only the central part is mutually fixed on the surface of each planar layer. Stick.

According to the invention of claim 7, only the plane layer having the smallest linear expansion coefficient is constrained by the holder, and the plane layer having the large linear expansion coefficient can freely expand and contract.
Therefore, when receiving heat, the inner peripheral wall of the nozzle hole is displaced at the interface between the plane layer having a small linear expansion coefficient and the plane layer having a large linear expansion coefficient, and deposits formed on the surface of the inner peripheral wall of the nozzle hole are separated from the surface of the inner peripheral wall of the nozzle hole. It is peeled off.
Furthermore, in addition to the effect of suppressing the accumulation of deposits, the center part of each planar layer is fixed, so the center axis of the injection hole formed in each planar layer does not shift, and stable fuel injection is realized. it can.

  In the invention of claim 8, the inflow side plane layer and the ejection side plane layer are configured such that a linear thermal expansion coefficient increases from the inflow side toward the ejection side.

According to the eighth aspect of the present invention, in addition to the effect of suppressing the accumulation of deposits, the inflow side plane layer surface and the valve body bottom surface can be disposed in close contact with each other when not receiving heat. Stable fuel injection can be realized without fuel leaking into the gap between the flat layer surface and the valve body bottom surface.
Therefore, the reliability as a fuel injection device is further improved.

  In a ninth aspect of the present invention, the nozzle hole plate is provided with a plurality of nozzle holes on a virtual circle.

  According to the invention of claim 9, deposits formed on the inner peripheral wall surface of the plurality of injection holes formed on the injection hole plate can be peeled off from the surface of the injection holes at a time, and deposit accumulation is further suppressed, It is possible to provide a fuel injection device that does not cause a decrease in the injection amount or an abnormality in the spray shape.

First, the configuration of an injector 1 as a fuel injection device 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.
For example, the injector 1 is attached to an unillustrated intake port when used as a fuel injection device for a premixed engine, and is attached to an unillustrated engine head when used as a fuel injection device for a direct injection engine. When mounted and used as a fuel injection device for a rich spike, it is mounted on an exhaust port (not shown).

The injector 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 housed and fixed in a cylindrical holder 140, a valve body 120 placed so as to be movable in the axial direction within the valve body 130, and a tip of the valve body 130 It is comprised by the nozzle hole plate 11 pinched between the front-end | tips of the holder 140. FIG.
The injection hole plate 11 which is the main part of the present invention is composed of a plurality of layers including an inflow side plane layer 110a and an ejection side plane layer 110b from the base end side, that is, the fuel inflow side to the tip end side, that is, the fuel ejection side. In addition, the inflow side planar layer 110a and the ejection side planar layer 110b are formed of members having different linear thermal expansion coefficients.

  The holder 140 is formed in a cylindrical shape, and a holder bottom 141 that is bent toward the center of the axis while the tip is open is formed on the tip side.

  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 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. 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 the fuel introduced into the fuel flow path 125 blocks the outflow from 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 proximal end, that is, toward the fixed core, and the contact portion 121 is separated from the valve seat 132.
When the contact portion 121 is separated from the valve article 132, the fuel 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 11.

  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 fuel from the fuel flow path 125 to the nozzle hole plate 11 is blocked, and fuel injection is stopped.

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

With reference to FIG. 2, the first embodiment of the present invention will be described in detail.
Fig.2 (a) is an expanded sectional view showing the fuel-injection part 10 of the injector 1 as a fuel-injection apparatus in the 1st Embodiment of this invention.
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 nozzle hole plate 11, the cylindrical holder 140 that holds the valve body 130 and the nozzle hole plate 11 on the inside thereof, and the valve element contact portion 122 are 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.

In the present embodiment, the inflow side plane layer 110a and the ejection side plane layer 110b are made of individual plate-like members having different linear thermal expansion coefficients, and the front end side surface of the inflow side plane layer 110a and the ejection side plane layer 110b. The base end surface is joined over the entire surface to form an integral plate member 110.
In addition, each material is selected so that a linear thermal expansion coefficient may become large in order of the holder 140, the inflow side plane layer 110a, and the ejection side plane layer 110b.

  The plate-shaped member 110 is disposed at a position where the proximal-side plane of the inflow-side planar increase 110 a and the proximal-side surface of the bottom 131 of the valve body 130 come into contact with each other. The outer peripheral edge fixing portion 112 is formed by being fixed to the peripheral wall by a method such as welding.

The inflow side flat layer 110a and the ejection side flat layer 110b of the plate-like member 110 are aligned with the axial center C / L of the injector 1 while the injection holes 111a and 111b constituting the injection holes 111 are aligned with the central axis. On the other hand, the injection hole plate 11 is formed by providing an injection hole formation angle θ in which the injection direction extends toward the tip.
Further, as shown in FIG. 2B, a plurality of nozzle holes 111 are formed at equal intervals on a virtual circle φD ₂ concentric with the injector 1.

An effect when the injector 1 according to the first embodiment of the present invention is mounted on an engine head of a direct injection engine (not shown) will be described.
Since the fuel injection section 10 of the injector 1 is at room temperature when stopped, the nozzle hole plate 11 is not thermally expanded, and the temperature for receiving heat is low during fuel injection, so the fuel injection section 10 and the nozzle hole of the injector 1 are low. The deformation of the plate 11 due to thermal expansion is slight.
After the fuel is injected from the injector 1 into the internal combustion engine, if a combustion explosion occurs due to ignition, the fuel injection unit 10 receives high combustion heat, and the nozzle hole plate 11 is greatly deformed by thermal expansion.

At this time, since the linear thermal expansion coefficient of the ejection side planar layer 110b is larger than the linear thermal expansion coefficient of the inflow side planar layer 110a, the nozzle hole plate 11 is convex toward the tip as shown in FIG. as will be, curved only the injection hole plate deflection amount P ₁ distally, with the curvature of the injection hole plate 11, injection hole 111 is also bent by the injection hole deflection of P _2.
Therefore, as shown in FIG. 3B, the shear force S <b> 2 in the peeling direction acts on the deposit 40 that has been volumed on the surface of the nozzle hole 111 in addition to the shear force S <b> 1 in the surface direction.
In particular, when the engine is started after being stopped for a long time, the injector 1 is completely cooled, and the deposit 40 formed on the surface of the injection hole 111 is hardened by the cooling. Since the shearing force in the peeling direction due to the bending is received, the effect of peeling the deposit 40 formed on the surface of the nozzle hole 111 is the greatest.

  In this embodiment, the inflow side flat layer 110a is formed into a plate using stainless steel SUS316, and the ejection side flat layer 110b is formed into a plate using stainless steel SUS304, and these are overlapped by cold rolling. The laminated plate-like member 110 was formed, and the injection hole 111 was formed in the plate member 110 to form the injection hole plate 11. The holder 140 was formed using stainless steel SUS410.

Since the elongation due to the thermal expansion of the inflow side planar layer 110a and the elongation due to the thermal expansion of the ejection side planar layer 110b are larger than the elongation due to the thermal expansion of the holder 140, the nozzle hole plate 11 is convex toward the tip side. deflect only the injection hole plate deflection amount P ₁ in.

In this embodiment, the relationship between the injection hole plate deflection amount P ₁ and the heat receiving temperature shown in FIG. 4 (a), showing the relationship between the injection hole bending amount P ₂ and the heat receiving temperature in Figure 4 (b).
The characteristic value of the average linear expansion coefficient of stainless steel SUS410 from 0 ° C. to 200 ° C. is 10.0 × 10 ⁻⁶ / ° C., and the characteristic value of the average linear expansion coefficient of stainless steel SUS316 from 0 ° C. to 200 ° C. is 16.1 × 10 ⁻⁶ / ° C., and the characteristic value of the average linear expansion coefficient of stainless steel SUS304 from 0 ° C. to 200 ° C. is 17.5 × 10 ⁻⁶ / ° C. Therefore, the outer diameter dimension φD ₁ is In the case of the φ5.0 mm nozzle hole plate 11, when the temperature changes from 0 ° C. to 200 ° C., the stainless steel SUS410 expands by 10.0 μm, the stainless steel SUS316 expands by 16.1 μm, and the stainless steel SUS304 expands. 17.5 μm expansion.
When the inflow side planar layer 110a, the ejection side planar layer 110b, and the holder 140 are combined as described above, when the temperature changes from 0 ° C. to 200 ° C., the nozzle hole plate 11 has a nozzle hole of about 13 μm. becomes the plate deflection amount P ₁ curved toward the distal end side, with this, the inner surface of the injection hole 111, curved become injection hole bending amount P ₂ of about 1.5 [mu] m, deposit injection hole A shearing force in the direction of peeling from the inner surface of 111 is generated.

A second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 5A, the present embodiment is different from the first embodiment of the present invention only in the nozzle hole plate 11c, and the other parts are the same as those of the first embodiment. is there.
In this embodiment, a powder material having two or more different linear thermal expansion coefficients is used so that the linear thermal expansion coefficient gradually increases from the inflow side to the ejection side, and the blending ratio varies depending on the layer. After forming the integral plate-like member 110c with the gradient material mixed with the nozzle material, the nozzle hole 111c was drilled to form the nozzle hole plate 11c.
The plate-like member 110c can be formed so that the linear thermal expansion coefficient gradually changes by a manufacturing method such as powder metallurgy or plasma sintering.

  In this embodiment, not only metals such as stainless steel as in the first embodiment, but also ceramic materials such as alumina, silicon nitride, zirconia, etc. having a relatively low linear thermal expansion coefficient, alloy materials such as invar, and wires It is also possible to form an integral plate member 110c by inclining blending with a metal material having a large thermal expansion coefficient.

According to the present embodiment, as shown in FIG. 5B, when receiving heat, the nozzle hole plate 11c is bent toward the tip side by the nozzle hole deflection amount P ₁ c so as to be convex toward the tip, As the nozzle hole plate 11c is curved, the nozzle hole 111c is also bent by the nozzle hole deflection amount P ₂ c.
Therefore, in this embodiment, the same effect as the first embodiment can be obtained.

A third embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 6A, the present embodiment is different from the first embodiment of the present invention only in the nozzle hole plate 11d, and the other portions are the same as those of the first embodiment. is there.
The injection hole plate 11d is formed by forming the inflow side flat layer 110d and the discharge side flat layer 110e by individual plate-like members having different linear thermal expansion coefficients, and aligning the axial centers C / L so as to overlap with the injection hole 111d. The hole 111e is drilled so that the central axis coincides.

The inflow side flat layer 110d and the ejection side flat layer 110e are fixed to each other by welding or the like only at the center portions of the surfaces facing each other to form a flat interlayer fixing portion 112e.
Further, the inflow side flat layer 110d has a smaller linear expansion coefficient than the ejection side flat layer 110e, and only the outer peripheral edge of the inflow side flat layer 110d and the inner peripheral edge of the holder 140 are fixed by welding or the like to form the outer peripheral edge fixing portion 112d. is doing.
Further, a radial expansion gap 115e is provided between the outer peripheral edge of the ejection side flat layer 110e and the inner peripheral edge of the holder 140, and the front end side surface of the ejection side flat layer 110a and the base end side surface of the holder bottom 141 are formed. An axial expansion gap 115d is provided between them.

Therefore, at the time of heat reception, each planar layer extends outwardly around the planar interlayer fixing portion 112d, and the central axis virtual circle of the inflow side injection hole 111d is formed at the interface between the inflow side planar layer 110d and the ejection side planar layer 110e. φD ₃ (111d), and the center axis virtual circle of the ejection side nozzle hole 111e becomes φD ₃ (111e), and the difference is shifted by the center axis deviation amount P ₂ d.
Assuming that the virtual circle of the inflow side plane layer 110d is φD ₃ (110d) and the virtual circle of the ejection side 110e is φD ₃ (110e), the nozzle hole center axis deviation amount P ₂ d shows the relationship of Expression (1).
P ₂ d = (φD ₃ (110d) −φD ₃ (110e)) / 2 Formula (1)

  As schematically shown in FIG. 7A, in the present embodiment, the deposit 40 is pulled in a direction parallel to the nozzle holes 111d and 111e by thermal expansion in the axial direction during heat reception. In addition, since the extension of the ejection side planar layer 110e having a larger coefficient of linear thermal expansion is larger than the inflow side planar layer 110d, a shearing force acts in the radial direction, that is, the peeling direction of the deposit 40, and the deposit 40 has the inner peripheral walls of the nozzle holes 111d and 111e Is peeled off.

In FIG. 7B, as a specific example, the injection hole center axis virtual circle φD at the interface between the two plane layers when the inflow side plane layer 110d is formed of stainless steel SUS410 and the ejection side 110e is formed of stainless steel SUS304. _The expansion amount calculated from ₃ and the nozzle hole center axis deviation amount P ₂ d are shown.
For example, when the temperature changes from 0 ° C. to 200 ° C., φD ₃ (110d) expands by about 11.1 μm, and φD ₃ (110e) expands by about 6.3 μm. The nozzle hole center shift amount P ₂ d is generated.

A fourth embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 8A, in the present embodiment, only the nozzle hole plate 11f is different from the first embodiment of the present invention, and other parts are the same as those in the first embodiment. It is.
The injection hole plate 11f has three different linear thermal expansion coefficients, the plate-like member 110f having a thickness _{T 1, T 2, T 3} , 110g, gradually toward the ejection side 110h from the inflow side linear thermal Superposition is performed so that the expansion coefficient is increased, and only the outer peripheral edge of the plate-like member 110f forming the inflow side plane layer having the smallest linear thermal expansion coefficient is fixed to the inner peripheral edge of the holder 140 by welding or the like.
Only the central portion of the surface of the plate-like member 110f, the plate-like member 110g, and the plate-like member 110h forming the ejection side plane layer is fixed to each other by the plane interlayer fixing portions 112g and 112h, and the nozzle holes 111f, 111g, 111h is bored with the central axis aligned to form a nozzle hole plate 11f.
An outer peripheral gap 115g is provided between the outer peripheral surface of the plate member 110f and the inner peripheral surface of the holder 140, and an outer peripheral gap 115h is provided between the outer peripheral surface of the plate member 110g and the inner peripheral surface of the holder 140. An axial expansion gap 115f is provided between the distal end side surface of the plate-like member 110h forming the ejection side plane layer and the proximal end side surface of the holder bottom portion 141.

At the time of heat reception, as shown in FIG. 8B, the central axes of the nozzle holes 111f, 111g, and 111h are shifted by the center axis deviation amounts P ₂ f and P ₂ g.
Therefore, a shearing force in the direction of peeling the deposit is generated at the interface between the plane layers.

When the fuel injection device of the present invention is mounted on an exhaust port, fuel injection is performed when high-temperature exhaust gas is discharged into the exhaust port.
Therefore, in order to perform accurate fuel injection at the time of heat reception, injection holes are formed in the plate-like members that form the respective plane layers in consideration of the amount of thermal expansion so that the central axes of the injection holes of each plane layer coincide with each other at the time of heat reception. If provided, the effect of the present invention can be expected.
Further, when the fuel injection device of the present invention is mounted on the intake port, the heat receiving temperature is low. Therefore, if the injection hole plate is formed by selecting a material having a higher linear thermal expansion coefficient, the effect of the present invention is expected. it can.

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 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.

1 is a cross-sectional view showing the overall configuration of a basic fuel injection device in an embodiment of the present invention. (A) is principal part sectional drawing in the 1st Embodiment of this invention, (b) is an arrow top view in this figure. (A) The principal part expanded sectional view which shows the change at the time of the non-heat receiving and the heat receiving in the 1st Embodiment of this invention, (b) is a schematic diagram which shows the effect. (A) is a characteristic figure which shows the relationship between the nozzle hole deflection amount and heat receiving temperature in the 1st Embodiment of this invention, (b) is a characteristic figure which shows the relationship between nozzle hole deflection amount and heat receiving temperature. (A) is principal part sectional drawing in the 2nd Embodiment of this invention, (b) is a principal part expanded sectional view which shows the change in the time of non-heat receiving in this embodiment, and the time of heat receiving. (A) is principal part sectional drawing in the 3rd Embodiment of this invention, (b) is a principal part expanded sectional view which shows the change at the time of the non-heat receiving and heat receiving in this embodiment. (A) is a schematic diagram which shows the effect in the 3rd Embodiment of this invention, (b) is a characteristic view which shows the amount of thermal expansion of each plane layer in the specific example of this embodiment. (A) is principal part sectional drawing in the 3rd Embodiment of this invention, (b) is a schematic diagram which shows the effect of this embodiment. Sectional drawing which shows the example of the nozzle hole plate in which the deposit in the conventional fuel injection apparatus was accumulate | stored.

Explanation of symbols

1 Injector (fuel injection device)
DESCRIPTION OF SYMBOLS 10 Fuel injection part 11 Injection hole plate 110 Plate-like member 110a Inflow side plane layer 110b Injection side plane layer 111 Injection hole 111a Inflow side injection hole 111b Injection side injection hole 112 Outer periphery fixed part 120 Valve body 122 Valve body contact part 125 Fuel flow path 131 Valve body 132 Valve seat 140 Holder θ Injection hole drilling angle φD ₂ Virtual circle

Claims (9)

A cylindrical valve body mounted on an internal combustion engine and having a fuel flow path formed therein;
An injection hole plate that is disposed on the downstream side of the fuel flow path in the valve body and has injection holes for injecting fuel flowing out of the fuel flow path,
A cylindrical holder for holding the valve body and the nozzle hole plate on the inside thereof;
A valve body abutting portion, and the valve body abutting portion is seated on a valve seat formed on an inner peripheral wall of the valve body to close the fuel flow path; A valve body that opens the fuel flow path by separating from the seat;
In a fuel injection device comprising:
The nozzle hole plate is constituted by a plurality of plane layers including an inflow side plane layer and an ejection side plane layer from an inflow side into which the fuel flows in to an ejection side from which the fuel is ejected.
The inflow side plane layer and the ejection side plane layer are formed of members having different linear thermal expansion coefficients.   2. The fuel injection device according to claim 1, wherein the inflow side plane layer and the ejection side plane layer are configured by stacking different individual plate-like members.   3. The fuel injection device according to claim 2, wherein the inflow side plane layer and the ejection side plane layer are joined so that the surfaces of the opposing layers are fixed to each other over the entire surface.   The inflow-side plane layer and the ejection-side plane layer are formed of a gradient material mixed using a powder material having two or more different linear thermal expansion coefficients and having different blending ratios depending on the layer. The fuel injection device according to claim 1.   5. The fuel injection device according to claim 3, wherein the inflow side plane layer and the ejection side plane layer have an outer peripheral edge thereof fixed to an inner peripheral edge of the holder.   6. The fuel injection device according to claim 5, wherein the inflow side plane layer and the ejection side plane layer are formed of a member having a linear thermal expansion coefficient larger than that of the holder.   Of the plurality of planar layers, only the outer peripheral edge of the planar layer having the smallest linear expansion coefficient is fixed to the inner peripheral edge of the holder, and only the central portion is fixed to each other on the surface of each planar layer. The fuel injection device according to claim 2.   The said inflow side plane layer and the said ejection side plane layer were comprised so that a linear thermal expansion coefficient might become large toward the said ejection side from the said inflow side, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The fuel injection device described in 1.   The fuel injection device according to any one of claims 1 to 8, wherein a plurality of injection holes are disposed on a virtual circle in the injection hole plate.