JP3935107B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
Conventionally, in a fuel injection valve that swirls in a swirl groove formed on a downstream plane of a swirler (swivel body), the depth of the groove decreases from the outer periphery to the axis of the fuel injection valve. Such a shape was employed (see, for example, Patent Document 1).
[0003]
In addition, there is a conical surface on the downstream side of the swirler, and the swirl groove is inclined in the axial direction in contact with the conical surface of the valve seat to give an axial velocity component to the fuel at the swirl groove outlet ( For example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-5-231266 (FIGS. 26, 27, 28)
[Patent Document 2]
JP-A-10-213053 (pages 4-8, FIG. 2)
[0005]
[Problems to be solved by the invention]
The conventional fuel injection valve is configured as described above, and in Patent Document 1 described above, the inlet area of the swirl groove is made larger than the outlet area so as to create an oblique flow at the outlet of the groove. Since the passage on the upstream side of the groove is an axial passage formed by the gap between the swirler and the valve body, the main flow flows to the valve seat side of the groove at the inlet of the swirl groove, and the flow in the horizontal direction at the groove outlet turn into.
[0006]
As a result, the fuel flows out from the swirl groove outlet in a direction substantially perpendicular to the axial center of the valve, reaches the valve seat surface, and is rapidly given an axial speed component. Will cause disturbance and fluid loss.
Such a fluid loss decelerates the injected fuel at the outlet of the downstream injection port, suppresses atomization of the spray in the engine cylinder, and deteriorates the combustion state.
[0007]
In Patent Document 2, the conical surface of the swirler and the conical surface of the valve seat must be brought into close contact with each other in order to prevent fuel leakage. Becomes difficult, and a flow from a gap other than the swirl groove occurs.
In addition, since it is difficult to measure and manage the depth of the swirl groove, there is a problem that the variation due to processing increases, and the variation of the spray shape and the injection amount for each product increases.
[0008]
The present invention has been made in order to solve the above-described problems, and by providing an oblique component to the fuel flow at the exit portion of the swirl groove while ensuring the processing accuracy of the swirl groove, the fluid loss It is an object of the present invention to provide a fuel injection valve that can reduce the variation between products and can realize fine spray fine particles.
[0009]
[Means for Solving the Problems]
A fuel injection valve according to a first aspect of the present invention includes a hollow valve body, a valve seat provided at one end of the valve body and having an injection port, and a valve body that opens and closes the injection port while being in contact with the valve seat. , which was equipped with a swirler to provide the swirl to the fluid entering the jet inlet along with slidably supporting the valve body surrounding the valve body, a swirl grooves inlet, the fuel flow obliquely downward force In addition, a stepped shape is provided so that an inclined portion is provided on the swirler at the exit portion of the swirl groove.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 is a cross-sectional view showing a fuel injection valve according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 to show the shape of a swirler (swivel body), and FIG. 3 is in FIG. FIG. 4 is a sectional view showing a swirler alone, and FIG. 5 is a plan view as seen from the bottom.
The tip of the fuel injection valve 1 is inserted into the hole of the cylinder head of the engine via the seal member 2 to inject a conical spray into the cylinder.
[0011]
The solenoid device 3 includes a bobbin 6 around which a coil 4 is wound, and a core 7 installed on the inner periphery of the bobbin 6, and the winding of the coil 4 is connected to a terminal 8.
The core 7 has a hollow cylindrical shape so that the inside becomes a fuel passage, a compression spring 9 is installed in the hollow portion, and an amateur 10 is installed so as to face the tip of the core 7. Yes.
[0012]
The coil 4 is inserted into the housing 11, and then the core 7 is press-fitted into the housing 11, and then both are fixed by welding.
The rod 12 for fixing the position of the spring 9 is inserted into the inner peripheral portion of the core 7 and pushes the compression spring 9 to a position where the spring force has a predetermined injection amount characteristic. In this state, the outer periphery of the core 7 is pushed. It is fixed by caulking from the portion 7a.
[0013]
Further, in the fuel injection valve 1, a valve body 13 integrated with the armature 10, a valve seat 14 having a seat portion 14 a and an injection port portion 14 b, and fixed to the outer periphery of the valve seat 14, are formed in a metal donut shape. Provided is a ring-shaped ring 15, a swirler (swivel body) 16 for swirling the fuel, and a hollow valve body 17 in which the swirler 16 and the valve seat 14 are accommodated in the tip portion and the seal member 2 is attached to the outer peripheral portion. These constitute a valve device.
[0014]
The swirler 16 is in close contact with the valve seat 14 at a flat surface portion 16j provided on the bottom surface thereof, is press-fitted into the inner peripheral portion of the valve body 17 together with the valve seat 14, and is fixed by welding.
The valve body 13 is inserted into the valve body 17 in a slidable state by a sliding portion 13a with the valve body 17 and a sliding portion 13b with the swirler 16, and is axially contacted with the seat portion 14a of the valve seat 14. The position is fixed.
[0015]
The valve body 17 is press-fitted into the inner peripheral portion of the housing 11 with a plate 18 sandwiched between the valve body 17 and the housing 11 and fixed by welding.
The plate 18 is provided to adjust the air gap, which is the distance between the armature 10 and the core 7 when a current is passed through the coil 4, and depends on the relative axial position of the armature 10 and the core 7. The appropriate thickness is used.
[0016]
When an operation signal is sent from the microcomputer of the engine (not shown) to the drive circuit of the fuel injection valve 1, the fuel injection valve 1 is supplied with current from the terminal 8 to the coil 4, and includes the housing 11, the core 7, and the amateur 10. Magnetic flux is generated in the magnetic circuit, and the armature 10 is attracted to the core 7 side.
When the valve body 13 formed integrally with the amateur 10 is separated from the seat portion 14a provided on the valve seat 14 and a gap is formed between the valve body 13 and the seat portion 14, the fuel pressure is 1 MPa or higher. The fuel is injected into the engine cylinder from the injection port portion 14b, and fuel injection is started.
[0017]
The valve body 13 has its valve opening position determined by contact of the upper end surface 13c of the valve body 13 with the lower end surface of the plate 18, and fuel injection is continued for a period of several tenths of milliseconds to several milliseconds. Thereafter, the energization of the coil 4 is stopped by the off signal from the microcomputer, the electromagnetic force is reduced, and the valve body 13 starts to move in the valve closing direction by the restoring force of the spring 9, and after a few tenths of milliseconds, The fuel injection is completed when the seat portion 14a is reached.
[0018]
In a state in which a current flows through the coil 4, the fuel that has flowed into the inner peripheral portion of the core 7 from a fuel supply pipe (not shown) passes through the gap 13 d between the armature 10 and the valve body 13, and the valve body 13 and the valve body. 17 to 17a, and further through the swirler inner passage 16a, the swirler circumferential passage 16b, and a plurality of swirl grooves 16c extending in the radial direction eccentric to the axial center of the valve body 13, and the clearance between the valve body 13 and the swirler 16 Up to 16d.
The fuel further reaches the seat portion 14a through the gap between the valve body 13 and the valve seat 14, and is injected into the engine cylinder through the injection port 14b.
[0019]
In the swirler 16 according to the present invention, as shown in FIG. 3, by providing a ring 15 having a metal donut shape, a stepped shape is formed at the swirl groove inlet portion 16e, and further near the swirl groove outlet portion 16h. Is provided with an inclined portion 16g.
Thus, by providing the ring 15 and making it a stepped shape, a downward force is applied to the flow 16f at the fuel inlet, and a part of the upstream line near the swirl groove outlet 16h is further provided. By inclining 16g in the downstream direction, the flow of fuel at the groove outlet portion 16h can be inclined.
[0020]
By correcting the flow of the swirl groove 16c obliquely downward in this way, the fuel flowing out of the swirl groove outlet portion 16h does not change rapidly in the process toward the seat portion 14, and the injection Since it can reach the opening 14b, a conical spray with little loss of fluid and good atomization can be injected into the engine cylinder.
In addition, it is possible to provide an engine with improved fuel efficiency and less HC emission due to unburned fuel.
[0021]
The spray angle of the spray and the swirling force of the fuel that determines the flow rate greatly depend on the flow path cross-sectional area of the swirl groove outlet portion 16h, but the contact surface between the swirler 16 and the valve seat 14 is the center of the valve body 13. Since the plane 16j perpendicular to the axis is used, the accuracy of the flatness and perpendicularity of this portion is high, and the leakage of fuel from the gap between the contact surfaces is negligibly small. Therefore, it is possible to obtain a fuel injection valve with a high productivity with little variation in spray angle and flow rate.
[0022]
In FIG. 3, the ring 15 is used to form a stepped shape at the swirl groove inlet portion 16 e. However, the ring 15 and the valve seat 14 are integrally formed, and a part of the valve seat 14 is formed. You may make it provide a convex part.
[0023]
Embodiment 2. FIG.
6 is a cross-sectional view showing a tip portion of a fuel injection valve according to Embodiment 2 of the present invention.
In the present embodiment, a tapered surface 14c is formed on the upstream side of the seat portion 14a of the valve seat 14 to smoothly change the direction of fuel flow from the swirl groove 16c to the seat portion 14a. .
The taper surface 14c is set to have a taper angle for guiding the fuel in a direction located between the flow direction in the swirl groove outlet portion 16h and the flow direction in the vicinity of the seat portion 14a.
[0024]
Specifically, when the inclination angle of the inclined portion 16g of the swirl groove upstream line is set to 30 °, the flow velocity direction of the swirl groove outlet portion 16h becomes a flow velocity direction of 30 ° or less because there is some horizontal component, and the seat surface When the inclination angle of 14d and 50 °, the inclination angle of the tapered surface 14c will be set to 30 ° to 50 °, and a 40 ° in FIG.
[0025]
As described above, according to the present embodiment, on the upstream side of the seat surface 14d of the valve seat 14, the angle is smaller than the angle of inclination of the seat surface 14a, and the angle of inclination is larger than the angle of the inclined portion 16g of the swirl groove 16c. Since the tapered surface 14c is configured, the direction change of the fuel flow can be made smoother than in the case of the first embodiment, the fluid loss can be reduced, and the atomization of the spray can be further promoted.
[0026]
【The invention's effect】
According to the fuel injection valve of claim 1 of the present invention, a hollow valve body, a valve seat provided at one end of the valve body and having an injection port, and a valve that opens and closes the injection port while being in contact with the valve seat body and is than also provided with a swirler to provide the swirl to the fluid entering the injection port while slidably supporting the valve body surrounding the valve body, a swirl groove inlet portion, obliquely downward to the fuel flow A stepped shape is provided so that a large amount of force is applied , and a swirler at the exit of the swirl groove is provided with an inclined portion, so that a smooth fuel flow can be obtained, fluid loss is reduced, and spray atomization is reduced. Can be promoted.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a fuel injection valve according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is a cross-sectional view showing a single swirler.
FIG. 5 is a plan view showing a single swirler.
FIG. 6 is a sectional view showing a tip portion of a fuel injection valve according to Embodiment 2 of the present invention.
[Explanation of symbols]
13 Valve body, 14 Valve seat, 14a Seat surface, 14b Injection port, 14c Tapered surface,
15 ring, 16 swirler, 16e swirl groove inlet, 16g slope,
16h Swirl groove outlet, 17 valve body.

Claims (3)

A hollow valve body, a valve seat provided at one end of the valve body, having an injection port, a valve body that opens and closes the injection port by being in contact with the valve seat, and surrounds the valve body, In the fuel injection valve provided with a swirler that slidably supports and swirls the fluid flowing into the injection port,
A fuel injection valve characterized by being provided with a stepped shape so as to apply an obliquely downward force to the fuel flow, and provided with an inclined part in the swirler at the outlet part of the swirl groove.   The fuel injection valve according to claim 1, wherein the stepped shape is formed by providing a ring.   The taper surface which is smaller than the inclination angle of the said seat surface and larger than the angle of the said inclination part is provided in the upstream of the seat surface of the said valve seat, The Claim 1 or Claim 2 characterized by the above-mentioned. Fuel injection valve.

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