JP4123053B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve used for supplying ignition fuel to an internal combustion engine of an automobile and a method for manufacturing the same.
[0002]
[Prior art]
As disclosed in JP-A-6-207568, a fuel injection valve is generally provided with a nozzle having a fuel injection hole and a concave conical valve seat, an iron core at one end, and the concave conical valve at the other end. It has a movable valve with a spherical valve element seated on the seat, and adjusts the injection amount of fuel sprayed from the fuel injection hole by sliding the movable valve by applying electromagnetic force to the iron core is there.
[0003]
In such a fuel injection valve, in order to minimize the region of the non-swirl flow formed on the downstream side of the valve element and stabilize the fuel flow, a convex conical tip is formed at the tip of the spherical valve element. There was a bite.
[0004]
[Patent Document 1]
JP-A-6-207568 [0005]
[Problems to be solved by the invention]
However, the above-mentioned conventional conical pointed shape of the valve element is actually concentrated at the tip of the tip, so the tip is easy when force is applied in the axial direction (compression direction) or lateral direction. It was difficult to maintain a sharp shape during processing, particularly during mass production. Therefore, if care is taken not to crush the tip of the valve element when assembling the fuel injection valve, handling will be careful and productivity will be significantly reduced.If the tip is crushed, the required spray characteristics will be obtained. There was a problem that the yield was deteriorated.
[0006]
An object of this invention is to provide the front-end | tip shape of a movable valve which can obtain favorable spray characteristics and is easy to maintain shape accuracy.
[0007]
An object of this invention is to provide the method of shape | molding a desired front-end | tip valve | bulb part easily and reliably.
[0008]
[Means for Solving the Problems]
The present invention for solving the above problems includes a valve element portion comprising a Omobenko and distal valve element end, a distal valve member portion is located downstream of the contact portion of the valve seat portion, the distal end Is a convex cone tip shape having a round shape , and the tip portion of the tip valve element has a spherical shape centered at a position offset from the central axis of the movable valve .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 shows a longitudinal section of a fuel injection valve of an automobile gasoline engine employing the present invention.
[0010]
The fuel injection valve shown in FIG. 5 includes a concentric cylindrical core 1, a yoke 2, a coil 4 for generating magnetism, and a terminal bobbin 5 for energizing the coil 4. Inside the nozzle 6, a movable valve 3 for controlling the fuel injection amount by a magnetic circuit, a main valve element 3a at the tip thereof, a tip valve element 3c at the tip of the main valve element 3a, a magnetic circuit, and a movable valve are formed. 3, an anchor 13 for sucking 3, a joint pipe 14 for connecting the anchor 13 and the movable valve 3, a damper plate 17 sandwiched between the anchor 13 and the joint pipe 14, a rod guide 18 for supporting the movable valve 3, and pressing the movable valve 3 Mass pipe 7 and spring 8, adjuster 9 for adjusting the pressing force of the spring 8, ring 10 for adjusting the stroke amount of the movable valve 3, swirler 11 for imparting a turning force to the fuel, and orifice having a hole for determining the fuel injection amount In order to prevent the fuel from leaking from between the core 15 and the housing 12, the orifice sheet surface 15 c that contacts the plate 15, the valve element 3 c and seals the fuel. And a seal ring 16 for supporting the dry coil construction.
[0011]
Here, when the coil 4 of the fuel injection valve is energized, the anchor 13 is attracted to the core 1 by the magnetic force, the movable valve 3 is lifted, and a gap is formed between the main valve element 3a and the orifice seat surface 15c.
[0012]
The fuel pressurized to high pressure by the fuel pump passes through the core 1, the adjuster 9, the mass pipe 7, the fuel passage hole 18c of the rod guide 18, and the fuel passage 6a of the nozzle 6, and swirls by the swirler groove 11c formed in the swirler 11. A force is applied and sprayed from the injection hole 15a of the orifice plate 15 through a gap between the main valve element 3a and the orifice seat surface 15c. Thereafter, when the energization is stopped, the movable valve 3 comes into contact with the orifice seat surface 15c by the repulsive force of the spring 8, and the valve is closed to finish the fuel spraying.
[0013]
Next, the tip shape of the movable valve 3 of the present invention will be described with reference to FIG. The main valve element 3a is in contact with the orifice seat surface 15c and seals the fuel so that the contact portion is formed as a spherical surface. The size of the sphere is determined by the relationship with the surface area that receives the combustion pressure in the cylinder. That is, since the surface area which receives combustion pressure will become large if a ball | bowl is large, the pressing force of the spring 8 which presses the movable valve 3 will be defeated by combustion pressure, and it will become impossible to ensure sealing performance. On the other hand, when the spherical diameter is small, the gap with the orifice seat surface 15c becomes small, and a necessary amount of fuel cannot be injected. Due to the above restrictions, the spherical diameter of the main valve element 3a is set to φ2 mm in the case of this fuel injection valve. Further, at the tip of the main valve element 3a, a convex conical tip valve element 3c is provided in the downstream area of the contact part with the orifice seat surface 15c in order to make the non-swirl area of the fuel as small as possible. . The taper rise of the tip valve element 3c ensures that the sealing performance is ensured even when the main valve element 3a falls, and that a sufficient flow path during fuel injection must be ensured. It is desirable to be inside the contact portion with 15c. Further, the angle α of the cone needs to be injected without restricting the fuel injected from the gap between the main valve element portion 3a and the orifice seat surface 15c, and without weakening the turning force given by the swirler. Therefore, it is desirable that it is at least one degree larger than the angle β of the orifice sheet surface 15c.
[0014]
Here, the tip of the tip valve element 3c is provided with a substantially spherical roundness to alleviate stress concentration due to an external force. Two methods are proposed.
[0015]
1st Example is a case where the center of the front-end | tip valve | bulb part 3c shown in FIG. 1 has a substantially spherical center on the central axis of the main valve element part 3a.
[0016]
Further, in the second embodiment, as shown in FIG. 2, the center of the tip of the tip valve element 3c is substantially offset from the center axis of the main valve element 3a. The first and second embodiments of the present invention will be described in detail with reference to FIGS.
[0017]
3 and 4 show the relationship between the offset and the distance L from the aerial vertex to the tip of the tip valve element 3c.
[0018]
When the offset is 0, the tip shape of the main valve element 3a shown in the first embodiment (FIG. 1) is obtained, and as the offset 20 increases, the main valve element shown in the second embodiment (FIG. 2). It becomes the front-end | tip shape of the part 3a. That is, as the offset increases, the distance L decreases, and the non-swirl area of the fuel formed in the downstream area of the contact portion between the main valve element 3a and the orifice seat surface 15c can be narrowed. As a result, it is possible to obtain a tip valve element shape that is advantageous to the above.
[0019]
Next, a manufacturing method of the main valve element 3a of the fuel injection valve having the feature that the distance L can be freely changed by the combination of the radius of the substantially spherical end of the tip valve element 3c and the offset as described above will be described.
[0020]
For mass production of parts that require high precision such as the main valve element 3a, machining by grinding is often used, and grinding is performed with a grinding wheel formed into the shape of the workpiece as a typical process. Cylindrical grinding or centerless grinding is used. FIG. 6 shows the state of grinding of the main valve element 3a, but the grindstone corner 22c for grinding the tip valve element 3c with the grinding wheel 22 is the minimum radius dimension of the corner 21c of the dresser 21 used for molding. Constrained by That is, the minimum radius of the corner portion 21 c of the dresser 21 is determined by the formable radius of the abrasive grains protruding on the surface of the dresser 21. Assuming that the minimum radius of the corner 21c of the dresser 21 used in this grinding method is 0.3, the distance L to the tip is approximately 0.08 when the offset is 0 from the graph of FIG. Here, even with the same minimum radius 0.3, the distance L can be reduced to 0.05 by setting the offset to 0.04. Therefore, there is an effect in narrowing the region of the fuel non-swirl flow formed downstream from the contact portion between the main valve element 3a and the orifice seat surface 15c of the orifice plate 15.
[0021]
In addition, as shown in FIG. 4, if the distance L0.05 is obtained with an offset of 0, the dresser 21 corner 21c used for molding needs to be reduced to R0.2, and the molding radius of the abrasive grains is reduced. This is disadvantageous because it is difficult to obtain accuracy when forming a grindstone. However, the offset makes it possible to shorten the distance L without reducing the forming radius of the abrasive grains, so that it is formed in the downstream area of the contact portion between the main valve element portion 3a and the orifice seat surface 15c. This makes it possible to reduce the non-swirl area of the fuel, which is advantageous for the spray characteristics.
[0022]
As described above, by concentrating the tip of the main valve element 3a with a rounded or offset tip shape, stress concentration is reduced with respect to external force such as compression applied to the tip portion, and shape maintainability can be improved. As a result, handling is facilitated, and even in mass production, spray characteristics can be maintained and productivity reduction can be prevented.
[0023]
【The invention's effect】
According to the present invention, it is possible to easily handle the valve element of the movable valve during mass production and to obtain the valve element of the movable valve of the fuel injection valve having good fuel spray characteristics.
[0024]
According to the manufacturing method of the present invention, a desired tip valve element can be easily and reliably formed.
[Brief description of the drawings]
FIG. 1 is a detailed sectional view of a valve element of a fuel injection valve.
FIG. 2 is a detailed cross-sectional view of the valve element of the fuel injection valve of the present invention.
FIG. 3 is a detailed cross-sectional view of the valve element of the fuel injection valve of the present invention.
FIG. 4 is a detailed cross-sectional view of the valve element of the fuel injection valve of the present invention and a relationship diagram of the tip shape.
FIG. 5 is an overall structural view of a fuel injection valve of the present invention.
FIG. 6 is a detailed view of a method for processing the valve element of the fuel injection valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Yoke, 3 ... Movable valve, 3a ... Main valve | bulb part, 3c ... Tip valve | bulb part, 4 ... Coil, 5 ... Bobbin, 6 ... Nozzle, 6a ... Fuel passage, 7 ... Mass pipe, 8 ... Spring, 9 ... Adjuster, 10 ... Ring, 11 ... Swirler, 11c ... Swirler groove, 12 ... Housing, 13 ... Anchor, 14 ... Joint pipe, 15 ... Orifice plate, 15a ... Injection hole, 15c ... Orifice seat surface, 16 ... Seal ring, 17 ... damper plate, 18 ... rod guide, 18c ... fuel passage hole.

Claims (2)

An electromagnetic force having a nozzle having a fuel injection hole and a concave conical valve seat, and a movable valve having a movable iron core on one side and a substantially spherical valve element seated on the valve seat on the other side. In the fuel injection valve that adjusts the injection amount from the fuel injection hole by sliding the movable valve with the suction force generated by
The valve part is composed of a main valve part and a tip valve part, the tip valve part is located on the downstream side of the contact part of the valve seat part, and the tip has a rounded convex cone tip shape . The tip of the tip valve element has a spherical shape centered at a position offset from the center axis of the movable valve. An electromagnetic force having a nozzle having a fuel injection hole and a concave conical valve seat, and a movable valve having a movable iron core on one side and a substantially spherical valve element seated on the valve seat on the other side. In the fuel injection valve that adjusts the injection amount from the fuel injection hole by sliding the movable valve with the suction force generated by
The valve part is composed of a main valve part and a tip valve part, the tip valve part is located on the downstream side of the contact part of the valve seat part, and the tip has a rounded convex cone tip shape. The tip of the tip valve element is formed by cylindrical grinding or centerless grinding with a dresser shape capable of grinding a spherical shape centered at a position offset from the central axis of the movable valve. The fuel injection valve characterized by being.

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