JP4027862B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a structure of a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine.

  Conventionally, there is a fuel injection valve in which an injection hole penetrates obliquely with respect to the axis of the fuel injection valve, and a hemispherical injection chamber is provided between the valve seat and the injection port. Some chamfered to adjust the amount of chamfering (for example, see Patent Document 1).

JP 2000-303934 A

In conventional fuel injection valves, fuel is injected under a pressure close to the gas atmosphere downstream from the seat portion of the valve seat, so a sudden change in flow from the valve seat surface to the injection chamber causes fluid separation. As a result, a vortex is generated inside, and a large fluid loss occurs.
In addition, since the injection port is provided in the spherical injection chamber, there is a problem that even if the connecting portion is chamfered, the effect of reducing the flow change is small.

  The present invention has been made to solve the above-described problems, and suppresses the turbulence of the flow caused by the inclination of the injection port even when the injection port is inclined from the axis of the injection valve. An object of the present invention is to provide a fuel injection valve that can perform the above-described operation.

According to a first aspect of the present invention, there is provided a fuel injection valve comprising: a hollow valve body; a valve seat provided at one end of the valve body and having an injection port inclined with respect to the valve shaft; A valve body that opens and closes an injection port, and a revolving body that surrounds the valve body and slidably supports the valve body and that swirls fluid that flows into the injection port. And a taper length on the side where the angle between the inner wall surface of the injection port and the end surface of the valve seat is acute with respect to the axis of the valve seat (hereinafter abbreviated as the acute angle side) The taper surface is configured so that the angle formed by the inner wall surface of the injection port and the end surface of the valve seat with respect to the axis of the valve seat is larger than the taper length on the obtuse side (hereinafter abbreviated side). Is.

According to the fuel injection valve of the first aspect of the present invention, a hollow valve body, a valve seat provided at one end of the valve body and having an injection port inclined with respect to the valve shaft, and the valve seat are separated from and connected to each other. A valve body that opens and closes the injection port, and a revolving body that surrounds the valve body and slidably supports the valve body and that swirls the fluid that flows into the injection port. A tapered surface is provided between the valve seat portion and the injection port, and the angle formed by the inner wall surface of the injection port and the end surface of the valve seat with respect to the axis of the valve seat is an acute angle (hereinafter referred to as the acute angle side). The taper surface is set so that the angle formed between the inner wall surface of the injection port and the end surface of the valve seat with respect to the axis of the valve seat is larger than the taper length on the obtuse angle side (hereinafter abbreviated side). As a result, the flow of fuel on the acute angle side becomes smooth, and the flow rate on the acute angle side can be made closer to the flow rate on the obtuse angle side. In addition, a uniform spray with a balanced left and right can be realized.

Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 is a sectional view showing a fuel injection valve for in-cylinder injection according to Embodiment 1 of the present invention. In the figure, the fuel injection valve 1 is a solenoid device 2, a housing 3 which is a yoke portion of a magnetic circuit, and a magnetic circuit. The solenoid device 2 includes a coil assembly 7 and a coil 8. The solenoid device 2 includes a coil 4 and a core 4 that is a fixed iron core, an armature 5 that is a movable iron core of a magnetic circuit, and a valve device 6.

The valve device 6 includes a valve body 9, a hollow valve body 10, a swirler (swivel body) 11, a valve seat 12, a stopper 13, and a holder 14.
The valve body 10 is joined by welding after being press-fitted into the inner diameter portion of the holder 14.
The amateur 5 is coupled to the valve body 9 at the welded portion 5a.
The swirler 11 is press-fitted into the inner diameter portion of the valve main body 10, and the valve seat 12 is press-fitted into the valve main body 10 and then joined to the valve main body 10 at a welded portion 12a.
A metal sleeve 15 is disposed between the core 4 and the holder 14, and the sleeve 15 is fastened to the core 4 and the holder 14 by means such as welding. By being fastened in this way, the internal fuel is sealed so as not to leak.

Next, the operation will be described.
When an operation signal is sent from the microcomputer of the engine to the drive circuit of the fuel injection valve 1, a current is passed through the coil 8 of the fuel injection valve 1, and a magnetic circuit composed of the armature 5, the core 4, the housing 3 and the holder 14 is generated. Magnetic flux is generated, the armature 5 is attracted to the core 4 side, and the valve body 9 that is integrally formed with the armature 5 is separated from the valve seat portion 12c to form a gap.
Then, the high-pressure fuel flows from the inside of the valve body 10 through the gap between the valve seat portion 12c and the valve body 9 into the injection port 12b provided in the valve seat 12, and is then injected to the outside.

Next, when an operation stop signal is sent from the microcomputer of the engine to the drive circuit of the fuel injection valve 1, the current supply to the coil 8 is stopped, the magnetic flux in the magnetic circuit is reduced, and the valve element 9 is closed. The gap between the valve element 9 and the valve seat 12c is closed by the compression spring 16 that is pushed in the direction, and fuel injection is completed.
The valve body 9 slides with a sliding portion 9a between the valve body 9 and the swirler 11 and a sliding portion 9b between the valve body 9 and the valve body 10 as guide portions. The flange upper surface 9 c contacts the lower surface of the stopper 13.

Since the sliding portion 9b is a means for regulating the non-coaxiality (swing) of the valve body 9 in the radial direction with respect to the valve seat surface, the clearance of this portion is preferably set as small as possible. Is set to 10 μm or less (one-side gap of 5 μm or less).
The fuel reaches the injection port 12b through a gap portion between the valve body 9 and the valve seat 12. Further, the fuel is injected outside through the injection port 12b.

2 and 3 are enlarged sectional views showing the valve tip, and show a model case in which a hemispherical injection chamber 12f is provided as in the prior art.
As shown in FIG. 3, the angle θ ₁ formed by the flow direction A of the fuel from the hemispherical injection chamber 12f and the chamfered surface 12g, and the hemispherical injection chamber 12f are abolished, and are tapered (dashed line in FIG. 3). In this case, the relationship between the fuel flow direction B and the angle θ ₂ formed by the chamfered surface 12g is θ ₁ >> θ ₂ , and when there is an injection chamber 12f, the flow of fuel changes suddenly from the injection chamber 12f to the chamfered surface 12g. For this reason, the chamfered surface 12g can stagnate and cause carbon deposits to adhere.

Therefore, as shown in FIGS. 4 and 5, it is conceivable to eliminate the hemispherical injection chamber 12f and provide the chamfered surfaces 12h and 12i, but the amount of the chamfered surfaces 12h and 12i between the injection port 12b and the valve seat portion 12c. Therefore, the distances L ₁ and L ₂ between the joints of the valve seat portion 12c and the chamfered surfaces 12h and 12i and the seat portions (positions where the valve body 9 and the valve seat portion 12c are in contact) C and D are not constant, That is, the plane E including the joint between the valve seat portion 12c and the chamfered surfaces 12h and 12i is not parallel to the upper surface F of the valve seat 12.
Therefore, since the direction in which the fuel flows into the chamfered surfaces 12h and 12i is different at each position, the flow collides in the chamfered surface E, and the fuel flow is disturbed. This turbulent fuel flow causes deposit adhesion.
In particular, in the portion close to the seat portions C and D, the distance between the valve body 9 and the valve seat 12 is narrowed, and thus the fuel passage is also narrowed. Therefore, deposit adhesion causes a decrease in the flow rate.

Therefore, in the present invention, as shown in FIGS. 6 and 7, a tapered surface 21 is provided between the injection port 12b inclined with respect to the valve shaft and the valve seat portion 12c, and the axis of the valve seat 12 (injection valve). The taper length 21a on the acute angle α side is greater than the taper length 21b on the obtuse angle β side with respect to X. The taper length 21a is preferably configured to be 1.5 times or more of the taper length 21b.
Thus, the conventional injection chamber is eliminated, the portion where the fuel flow changes rapidly is eliminated, the valve seat surface is a tapered surface, and the valve seat portion 12c is formed between the seat portions C and D and the injection port 12b. By providing a tapered surface 21 having an opening angle θ ₄ smaller than the opening angle θ ₃ , the flow of fuel was made smooth.

Further, the intersection point G on the extension line of the valve seat portion 12c and the intersection point H on the extension line of the taper surface 21 are both present on the axis X of the valve seat 12, so that the valve seat portion 12c and the taper surface 21 are connected. It can also be configured concentrically.
The plane L including the joint is configured to be parallel to the upper surface F of the valve seat 12 by making the distance L from the seat portions C and D to the joint of the tapered surface 21 constant.

As shown in FIG. 8, when there is no taper at the connecting portion between the seat surface and the injection port 12b, the stagnation portion P becomes the largest.
In this case, the flow on the acute angle side generates a contracted flow and the flow velocity becomes slow, the balance between the flow on the obtuse angle side and the flow on the acute angle side where no contracted flow occurs is lost, and it is difficult to achieve uniform spraying.
On the other hand, as shown in FIG. 7, the acute angle side flow rate is made smooth by making the acute side taper amount 21a larger than the obtuse angle side taper amount 21b, thereby smoothing the flow of fuel on the acute angle side. It is possible to achieve a uniform spray with a good balance between left and right.

As described above, according to the present embodiment, by providing the largest taper 21a in the portion where the joint angle between the valve seat portion 12c and the injection port 12b is the acute angle, the fuel flow can be changed smoothly and deposited. Less adherence.
Further, by reducing the change angle of the direction of fuel flow from the valve seat portion 12c to the injection port 12b, fluid loss can be reduced and atomization of the fuel flow can be promoted.

Furthermore, since the joint between the valve seat portion 12c and the tapered surface 21 is constant from the seat portions C and D, the turbulence of the fuel flow in the vicinity of the seat portions C and D can be suppressed.
Also, by increasing the acute side taper amount 21a over the obtuse angle side taper amount 21b and smoothing the flow of the acute side fuel, the acute side flow rate can be made closer to the obtuse side flow rate, and the right and left balance It is possible to achieve uniform spraying with good removal.

Embodiment 2. FIG.
9 and 10 are enlarged sectional views showing a valve tip portion of a fuel injection valve for in-cylinder injection according to Embodiment 2 of the present invention. In this embodiment, an acute angle side taper 21a with respect to the axis X of the valve seat 12 is shown. in an angle alpha ₁ of the valve seat portion 12c and the tapered surface 21a, thereby configured to be equal to the angle alpha ₂ of the tapered surface 21a and the injection port 12b, and the length of the tapered surface 21a of the tapered surface 21b length It is configured to be larger than this.

As described above, by configuring α ₁ and α ₂ to be equal in the acute-side taper 21a with respect to the axis X of the valve seat 12, a portion where the fuel flow direction changes suddenly throughout the entire flow path can be eliminated. It is possible to minimize deposit adhesion and fluid energy loss.

It is sectional drawing which shows the fuel injection valve by Embodiment 1 of this invention. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view showing a valve tip part. It is an expanded sectional view which shows the valve front-end | tip part by Embodiment 2 of this invention. It is an expanded sectional view which shows the valve front-end | tip part by Embodiment 2 of this invention.

Explanation of symbols

9 Valve body, 10 Valve body, 11 Revolving body, 12 Valve seat, 12b Injection port,
12c Valve seat part, 21 taper surface.

Claims (2)

A hollow valve body, a valve seat provided at one end of the valve body and having an injection port inclined with respect to the valve shaft, a valve body that opens and closes the injection port while being in contact with the valve seat, and the valve body A fuel injection valve having a swirling body that slidably supports the valve body and that swirls the fluid flowing into the injection port, between the valve seat portion of the valve seat and the injection port. A taper surface is provided, and the taper length on the side where the angle between the inner wall surface of the injection port and the end surface of the valve seat is an acute angle with respect to the axis of the valve seat (hereinafter abbreviated as the acute angle side) is The tapered surface is configured such that the angle formed by the inner wall surface of the injection port and the end surface of the valve seat with respect to the axis of the seat is greater than the taper length on the obtuse angle side (hereinafter referred to as the obtuse angle side). A fuel injection valve characterized by. 2. The fuel injection according to claim 1, wherein, in the acute angle taper, an angle formed by the valve seat portion and the tapered surface is equal to an angle formed by the tapered surface and the injection port. valve.

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