JP2008128130A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve seat of the fuel injection valve injecting fuel into a cylinder of an internal combustion engine that spray distribution from an injection hole of the valve seat is made uniform in the circumferential direction. <P>SOLUTION: The injecting hole of the valve seat includes a sheet surface, a center of which corresponds to a center line of a valve body and which has a predetermined opening angle θ<SB>1</SB>, and a jet hole connecting with the seat surface downstream of the seat surface with a predetermined tile angle θ<SB>2</SB>with respect to the center line and penetrating to a lower side of the valve seat. On a line that perpendicular to the center line directed to the same direction of the jet hole, a line, an origin of which is a point away by predetermined eccentricity amount and which connects a line of radius R<SB>0</SB>with the seat surface, forms a taper surface with a predetermined angle θ<SB>3</SB>with respect to an upper surface of the valve seat, and the length of the taper surface has a maximum value on an eccentric line and decreases continuously from the maximum value on a circumference of radius R<SB>0</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection valve for an in-cylinder injection gasoline engine that directly injects fuel into a cylinder of an internal combustion engine, and more particularly to an improvement of a valve seat provided with a fuel injection port.

  As one structural example of a conventional fuel injection nozzle, in order to inject fuel into a prescribed spray shape, on the inlet side edge of the injection hole that penetrates the wall of the spherical concave surface of the fuel injection chamber of the valve seat in an inclined manner, A chamfered surface that forms a spherical continuous concave surface is formed, and the chamfered amount on the inner corner side of this chamfered surface is larger than the chamfered amount on the outer corner side. It is shown that the amount of chamfering is large, so that the contraction of the flow of the fuel is less likely to occur, the decrease in the flow velocity is reduced, and the difference in the flow velocity from the fuel flowing on the inner angle side / outer angle side is reduced (for example, Patent Document 1).

JP 2000-303934 A

However, in the valve seat disclosed in Patent Document 1, the chamfered inner chamfering amount continuous with the spherical concave surface at the inlet side edge of the nozzle hole is set larger than the outer chamfered chamfering amount, and the radius r gradually changes. However, it is not easy to ensure the accuracy of the chamfer radius r by the processing method disclosed in Patent Document 1. In addition, r dimension variations are likely to occur in the valve seats of a plurality of injection valves. In particular, when machining is performed so that the radius r gradually changes, it is particularly difficult to accurately process the r dimension, which causes variation.
Thus, in the valve seat which has a difficulty in ensuring dimensional accuracy and precision, there is a problem that it is not easy to inject into a prescribed spray shape.

  The present invention solves the above-described problems, and an object of the present invention is to obtain a desired spray shape by making the injection port of the valve seat an easily processable shape.

The fuel injection valve according to the present invention is a fuel injection valve in which a valve seat provided with an injection port at one end is disposed,
Injection port of the valve seat, and having a predetermined opening angle theta ₁ concentrically with respect to the valve body centerline of the fuel injection valve is opened with a seat surface bottom from the valve seat the upper surface to a predetermined depth valve A seat surface that contacts and separates from the main body, and has a predetermined inclination angle θ ₂ on the downstream side of the seat surface with respect to the center line of the valve main body, and is connected to the bottom of the seat surface and penetrates to the lower surface of the valve seat. The nozzle,
On the upper surface of the valve seat, on a line orthogonal to the valve body center line in the same direction as the direction in which the nozzle hole is inclined, with a predetermined radius R ₀ based on a point separated from the valve body center point by a predetermined eccentricity e. lines connecting the lines and the seat surface on the circumference of forming is formed in a tapered surface forming with respect to the valve seat upper surface at a predetermined angle theta _3, and a line the tapered surface is perpendicular to the valve body centerline In addition to having a maximum taper surface length value on the side where the amount of eccentricity e is set, it is formed so as to continuously decrease along the circumference.

The fuel injection valve according to the present invention is a fuel injection valve in which a valve seat provided with an injection port at one end is disposed,
Injection port of the valve seat, and having a predetermined opening angle theta ₁ concentrically with respect to the valve body centerline of the fuel injection valve is opened with a seat surface bottom from the valve seat the upper surface to a predetermined depth valve A seat surface that contacts and separates from the main body, and has a predetermined inclination angle θ ₂ on the downstream side of the seat surface with respect to the center line of the valve main body, and is connected to the bottom of the seat surface and penetrates to the lower surface of the valve seat. The nozzle,
On the upper surface of the valve seat, on a line orthogonal to the valve body center line in the same direction as the direction in which the nozzle hole is inclined, with a predetermined radius R ₀ based on a point separated from the valve body center point by a predetermined eccentricity e. lines connecting the lines and the seat surface on the circumference of forming is formed in a tapered surface forming with respect to the valve seat upper surface at a predetermined angle theta _3, and a line the tapered surface is perpendicular to the valve body centerline The maximum taper surface length value is set on the side where the amount of eccentricity e is set, and is formed so as to continuously decrease along the circumference, so that the fuel generated when flowing from the taper surface into the seat surface The non-uniformity in the circumferential direction of the spray and the non-uniformity of the spray that occurs when flowing from the seat surface into the nozzle are canceled out, and the non-uniformity in the circumferential direction of the fuel injected from the nozzle is eliminated. Uniform desired conical spray distribution There is an effect that can be obtained.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 shows an overall cross section of the fuel injection valve 1, and a cylinder (not shown) is provided at the bottom of FIG. The solenoid unit 2 that generates electromagnetic force comprises a core 4 that is a fixed iron core, a ring 5 that is made of a non-magnetic member, a holder 6 and a housing 7, which forms a magnetic circuit, and each coil 9 housed in a terminal 8. It consists of elements.
The valve body 3 includes a swirler 10 that generates a swirl flow in the fuel, a body 14 to which a valve seat 11 is fixed, and a needle 15 that is a valve body having an armature 16. The needle 15 includes the body 14 and the swirler 10. It is slidably inserted into the valve seat 11 and operates so as to come in contact with and separate from the valve seat 11. The sealing force of the needle 15 with respect to the valve seat 11 is generated when a spring 17 installed in the core 4 is applied with fuel pressure to a valve seat area by a predetermined spring force set by the rod 18 and a valve seat diameter. Determined by physical strength.

Next, when the coil 9 is excited by a valve opening signal from a controller (not shown), a suction force is generated between the armature 16 to which the needle 15 is connected and the core 4 which is a fixed iron core, and the spring force and fuel pressure by the spring 17 are generated. When the suction force exceeds the sum of the fluid forces generated by the above, the tip of the needle 15 separates from the valve seat 11, that is, opens. At that time, the opening area of the seat portion is determined by the lift amount regulated by the needle 15 coming into contact with the stopper 19. The tip of the needle 15 is in contact with the valve seat 11, that is, when the valve is closed, the coil 9 is not excited by the valve closing signal from the controller, and is closed by the spring force.
Here, with respect to the flow of fuel, high-pressure fuel (for example, fuel pressure is 10 MPa) is supplied to the fuel injection valve 1 through a delivery pipe (not shown) from a fuel applied at a high pressure from a fuel pump (not shown). When the valve is closed, the needle 15 in the fuel injection valve 1 and the seat portion of the valve seat 11 are filled with high-pressure fuel. The needle 15 is opened by a valve opening signal from a control controller (not shown), and fuel to which a turning force is applied by the swirler 13 is injected from a nozzle 11c provided in the valve seat 11 in a predetermined direction.

The valve seat 11, which is the main part of Embodiment 1 of the present invention, will be described in detail with reference to FIG.
FIG. 2A is a sectional view showing only the valve seat 11, and FIG. 2B is a plan view thereof. In the figure, the fuel injection port 50 provided in the valve seat 11 is formed by a seat surface 11a portion, a tapered surface 11b portion, and an injection port 11c portion to which the needle 15 not shown in FIG. Yes.

Seat surface 11a, the sheet concentric relative to the center line Y-Y of the valve body 3 of the fuel injection valve 1, a predetermined from the valve seat top 11U at a predetermined opening angle theta ₁ the depth H of FIG. 1 The sheet surface 11a is formed by opening as the surface bottom portion 11d. With respect to the center line Y-Y at the downstream side of the valve body 3 of the sheet surface 11a, together with the injection port 11c having penetrated diameter d to reach the valve seat the lower surface 11L at a predetermined nozzle hole inclination angle theta ₂ is formed On the XX line orthogonal to the center line YY in the direction in which the nozzle hole 11c is inclined (left side of the center line YY in FIG. 2B) on the upstream side of the seat surface 11a, A line connecting the circumference of the valve seat upper surface 11U formed at a predetermined radius _R0 with a point separated from the center point C of the main body 3 by a predetermined eccentricity e as a base point, and the seat surface 11a, tapered surface 11b which forms a predetermined taper angle theta ₃ is formed against the valve seat top surface 11U. In the example of FIG. 2B, the taper surface 11b has a maximum taper surface length value on the left side on the line XX orthogonal to the center line YY, that is, the side where the eccentric amount e is set. It is provided so as to decrease continuously along the circumference. That is, the leftmost taper surface 11b on the XX axis in FIG. 2B has the maximum taper surface length lm, and the rightmost taper surface 11b on the XX axis has the shortest taper surface length ls. have.

  In the fuel injection valve 1 including the valve seat 11 according to the first embodiment shown in FIG. 2, the taper surface 11b is eccentric with respect to the seat surface 11a provided on the center line of the valve body 3, and the seat surface 11a Since it is provided on the upstream side, when the fuel flows from the tapered surface 11b into the seat surface 11a, the fuel distribution is uneven in the circumferential direction. In addition, the fuel flow from the seat surface 11a to the nozzle hole 11c is also biased.

The reason will be described based on the structural characteristics of the valve seat 11 according to the first embodiment. Representative positions of intersections between the taper surface 11b and the sheet surface 11a are shown in FIGS. 2A and 3A and 3B. Part A is a part having the maximum taper surface length lm, and part B is a part having the minimum taper surface length ls. The fuel flow path resistance r ₁ is present in the flow path passing through the part A, and the fuel flow path resistance r ₂ is present in the flow path passing through the part B. As shown in FIG. 3, the length of the flow path existing in the gap between the needle 15 and the valve seat 11 when the needle 15 is away from the valve seat 11 is shorter on the part A side than on the part B side. Therefore, the resistance of the fuel flow path flowing via the part A side is smaller than that on the part B side. That is, r ₁ <r ₂ . The resistances r ₁ and r ₂ continuously change over the circumference of the tapered surface 11b. The fuel flowing into the seat 11a from the tapered surface 11b is affected by the resistances r ₁ and r ₂ , and the flow distribution has a difference continuously on the circumference. That is, the fuel flow injected into the valve seat upper surface 11U is contracted at the part A and the part B, respectively. Since the flow path resistance is larger on the part B side than on the part A side, the flow velocity is lower than that on the part A side. In this way, a difference occurs in the fuel flow velocity, and a flow velocity difference occurs on the circumference of the entire seat surface 11a.
On the other hand, fuel flow path resistances r ₃ and r ₄ exist at the portions C and D, which are the intersections of the seat surface bottom portion 11d and the nozzle hole 11c. Since the shape change of the part C> the shape change of the part D, r ₃ > r _{4 is} satisfied, and therefore the fuel flow velocity distribution has a continuous difference on the circumference.

In the valve seat 11 according to the first embodiment, when the fuel flowing into the valve seat 11 flows from the taper surface 11b upstream of the valve seat 11 via the seat surface 11a and the injection hole 11c, for example, as shown in FIG. Assuming the case of flowing through the valve seat cross section, there are a flow path passing through the flow path resistance r ₁ + r ₃ and a flow path passing through r ₂ + r ₄ as described above.

In order to obtain a desired conical spray distribution with improved uniformity in the circumferential direction of the fuel injected from the nozzle hole 11c, the flow path resistance r ₁ + r ₃ = r ₂ + r ₄ is set to the nozzle hole 11c. It is possible to obtain the effect that the non-uniformity of the flow velocity on the circumference when the fuel flows in cancels each other.
The respective channel resistances r _{1 to} r ₄ can be determined by appropriately setting the sheet surface opening angle θ ₁ , the nozzle opening inclination angle θ ₂ , and the taper angle θ ₃ .

2 take various values depending on the type and size of the cylinder, the layout of the fuel injection valve 1 relative to the cylinder, and the like. For example, the seat opening angle θ ₁ is 45 °. ˜80 °, the nozzle inclination angle θ ₂ is 10 °, and the taper angle θ ₃ that opens the taper on one side is larger than the seat surface opening angle θ ₁ , that is, θ ₃ > 1/2 (θ ₁ ), for example, θ ₁ When the angle is 90 °, the angle is 50 ° to 60 °. Further, the eccentricity e = 0.1 to 0.3 ^mm , R ₀ = 2 to 2.2 ^mm, and the nozzle ^diameter d = 0.3 to 1.3 mmφ.

The fuel flow in the valve seat 11 according to the above description is schematically shown in FIG. As can be seen from the figure, the flow resistance r ₁ on the A part side <the flow resistance r ₂ on the B part side, so the fuel flow rate on the A part side> the fuel flow rate on the B part side, but the flow resistance on the C part side Since r ₃ > flow rate resistance r ₄ on the D part side, the fuel flow rate on the C part side <the fuel flow rate on the D part side, and eventually the fuel flow is made uniform at the inlet 11c inlet, and injection from the outlet 11c is desired. A conical spray distribution is obtained.
As a matter of course, a desired spray distribution can be obtained by optimizing the aforementioned θ _{1 to} θ ₃ set based on the cylinder capacity, the fuel injection valve size, and the like.

In addition, in order to make it easy to understand the spray distribution injected from the nozzle 11c by providing the tapered surface 11b of the first embodiment, the spray distribution in the case of a valve seat without a tapered surface is shown in FIG. .
From the comparison between FIG. 3 and FIG. 4, the improvement of the spray distribution state according to the first embodiment in which the tapered surface is provided eccentric to the central axis is clear.

Embodiment 2. FIG.
In the second embodiment, the valve seat 11 is manufactured by a metal injection (MIM) method.
The metal injection method, as is well known, kneads metallic fine powder and a resin binder, injection-molds the kneaded material from the injector, removes the binder with a solvent, and sinters the compact. It is a manufacturing method.
When the valve seat 11 shown in the first embodiment is manufactured by metal injection, there is an effect that an eccentric taper surface can be manufactured easily and inexpensively.

  Embodiments 1 and 2 of the present invention can be used for a fuel injection valve that injects fuel into a cylinder of an internal combustion engine.

It is a figure which shows the whole cross section of the fuel injection valve of Embodiment 1 of this invention. It is a figure which shows the valve seat of Embodiment 1 of this invention. It is a figure which shows typically the fuel flow in the valve seat of Embodiment 1 of this invention. It is a figure which shows typically the fuel flow in the valve seat without an eccentric taper surface.

Explanation of symbols

1 fuel injection valve, 3 valve body, 11 valve seat, 11a seat surface,
11b taper surface, 11c nozzle, 11d seat surface bottom, 11L valve seat bottom surface,
11U upper surface of valve seat, 50 injection port, e eccentricity, R ₀ radius,
θ ₁ sheet surface opening angle, θ ₂ nozzle tilt angle, θ ₃ taper angle,
Y-Y Valve body center line.

Claims (2)

A fuel injection valve having a valve seat provided with an injection port at one end,
The injection port of the valve seat has a predetermined opening angle θ ₁ concentric with the center line of the valve body of the fuel injection valve, and has a seat surface bottom portion at a predetermined depth from the upper surface of the valve seat. A seat surface that is opened and contacts and separates from the valve body, and has a predetermined inclination angle θ ₂ on the downstream side of the seat surface with respect to the center line of the valve body, and is connected to the bottom of the seat surface and is connected to the bottom of the seat surface A nozzle hole penetrating to
On the valve seat upper surface, on a line orthogonal to the valve body center line in the same direction as the direction in which the nozzle hole is inclined, a predetermined radius with a point away from the valve body center point by a predetermined eccentricity e A line connecting the line on the circumference formed by R ₀ and the seat surface is formed by a tapered surface formed at a predetermined angle θ ₃ with respect to the upper surface of the valve seat, and this tapered surface is the center of the valve body. A fuel injection having a maximum taper surface length value on a side where the eccentricity e on a line orthogonal to the line is set and continuously decreasing along the circumference valve. The fuel injection valve according to claim 1, wherein the valve seat is manufactured by a metal injection method.

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