JP4020855B2 - Fuel injection valve and manufacturing method thereof - Google Patents

Description

  The present invention relates to a fuel injection valve for direct injection in a gasoline cylinder and a method for manufacturing the same.

  In a conventional fuel injection valve, a plurality of slits are formed in a valve seat member constituting the fuel injection valve to form a fan-shaped spray (for example, see Patent Document 1).

JP 2000-205088 A

  In the conventional fuel injection valve as described above, in order to eject the fan-shaped spray, the slit formed in the valve seat is formed so that its width increases toward the downstream side of the injection. However, when the slit is formed by electric discharge machining, since the electric discharge mold is almost the same as the slit shape, the electric discharge mold is deformed by melting at the time of machining. There is a problem in that it is necessary to manufacture one mold for each slit, and the manufacturing cost of the mold is high.

  The present invention has been made to solve the above-described problems, and provides a fuel injection valve capable of reducing the manufacturing cost at a low cost while accurately forming the slit portion of the fuel injection valve. It is another object of the present invention to provide a manufacturing method thereof.

A fuel injection valve according to the present invention is a fuel injection valve that opens and closes the fuel flow path by bringing a valve body provided in the fuel flow path into and out of contact with a valve seat so that the fuel injection / injection end state is achieved. The valve body has a substantially frustoconical spray piece having a tapered surface that spreads at an arbitrary angle toward the injection downstream side from the seat portion in contact with the valve seat on the downstream side of the fuel flow path. The spray piece has an inner peripheral surface in contact with the taper surface, and the taper surface of the spray piece is formed with an inclined groove whose cross-sectional area increases toward the downstream side of injection , and the groove centerline of the inclined groove is It is formed so as to be inclined at a predetermined angle with respect to a plane passing through the axis of the spray piece, and the inclined groove becomes a part of the fuel flow path.

In the fuel injection valve according to the present invention, the first and second grooves are formed on the tapered surface of the spray piece, the first groove is the inclined groove, and the second groove is It is a groove formed so as to be positioned on a plane passing through the axis of the spray piece having a substantially truncated cone shape.

  Furthermore, the fuel injection valve manufacturing method according to the present invention includes a step of joining the spray piece to the valve seat by laser welding in the manufacturing process of the fuel injection valve as described above.

According to the fuel injection valve of the present invention, the fuel injection valve is configured to open and close the fuel flow path by bringing a valve body provided in the fuel flow path into contact with the valve seat so that the fuel injection / injection end state is achieved. The valve body has a substantially frustoconical spray piece having a tapered surface extending at an arbitrary angle toward the injection downstream side of the fuel flow channel downstream from the seat portion in contact with the valve seat, The spray piece has an inner peripheral surface in contact with the taper surface, and the taper surface of the spray piece is formed with an inclined groove whose cross-sectional area increases toward the injection downstream side, and the groove center line of the inclined groove is Since the inclined groove is formed as a part of the fuel flow path with respect to a plane passing through the axis of the spray piece, the groove formed on the tapered surface of the spray piece is formed by cutting. Can be good Get the injection state, it is possible to suppress the manufacturing cost cheaper.

According to the fuel injection valve of the present invention, the first and second grooves are formed on the tapered surface of the spray piece, the first groove is the inclined groove, and the second groove Is a groove formed so as to be positioned on a plane passing through the axis of the spray piece having a substantially frustoconical shape, so that the spray angle can be changed between the first groove and the second groove. By forming the first groove and the second groove in the same spray piece, it becomes possible to arbitrarily adjust the spray angle of the spray depending on the position where the fuel is sprayed.

  Furthermore, according to the method for manufacturing a fuel injection valve of the present invention, since the step of joining the spray piece to the valve seat by laser welding is included, the fastening reliability between the spray piece and the valve seat can be improved.

Embodiment 1 FIG.
1 is a cross-sectional view showing a configuration of a fuel injection valve according to Embodiment 1 of the present invention, and FIG. 2 is a fuel injection valve centering on a valve seat corresponding to a slit portion of the fuel injection valve and a spray piece forming position. It is a downstream end part expanded sectional view. As shown in FIGS. 1 and 2, the fuel injection valve 1 mainly includes a solenoid device 2, a valve device 8, a fuel supply pipe 15, and the like. The fuel supply pipe 15 is supplied with gasoline as fuel via a low-pressure fuel pump and a high-pressure fuel pump from a fuel tank (not shown). In FIG. 1, the fuel supply pipe 15 is located upstream of the fuel flow path, and the spray piece 12 side of the valve device 8 is located most downstream.

  A filter 21 made of a resin part with a nylon mesh 22 is disposed downstream from the fuel supply pipe 15 so that foreign matters in the fuel do not enter the fuel supply valve 15. An O-ring 24 and a backup ring 23 that is a resin supporting the O-ring 24 are disposed.

  A solenoid device 2 is disposed on the downstream side of the filter 21. The solenoid device 2 is a resin component for winding the rod 7, the spring 6, the coil 5, the core 4, and the coil 5. A copper plate is disposed upstream of the component. It is mainly composed of a bobbin 18 on which a terminal 20 as an electrode of the above is disposed, a housing 3 that supports the core 4, and a ring 25 for fuel seal. The upper portion of the housing 3 is fixed by a fuel injection valve presser 17.

  A valve device 8 is disposed on the downstream side of the solenoid device 2. The valve device 8 surrounds the valve body 9, the armature 10 disposed on the upper outer peripheral side of the valve body 9, and the lower portion of the valve body 9. A valve body 11 that contacts the downstream end of the valve body, a guide 13 that is disposed inside the valve body 11 and supports the valve body 9, a seal member 14 for fixing the valve body 11, the armature 10, and a valve device that surrounds the outer periphery of the valve body 11 The component 26 is mainly composed of a washer 16 for pressing and fixing the valve device component 26 against the cylinder head 19 side of the engine, and a spray piece 12 incorporated into the lower portion of the valve body 11 by press-fitting from the downstream side of the fuel flow path. Yes.

As shown in FIG. 2, the tip (lower end) of the valve body 9 is in contact with the seat portion 11 a at the lower part of the valve body 11. An inner peripheral surface of the seat portion 11a of the valve body 11 is formed in a conical surface. The valve body 11 has a valve seat portion (corresponding to a valve seat) 11c on the downstream side from the seat portion 11a. The spray piece 12 is disposed at the most downstream position of the fuel flow path of the valve seat portion 11c. 12 has an inner peripheral surface (corresponding to the tapered surface portion 11b) in contact with the tapered surface. The spray piece 12 is formed in a substantially truncated cone shape (a trapezoidal cross-sectional shape with a conical side surface on the outer periphery), and a fuel flow path is formed on a tapered surface that extends toward the downstream side of injection at an arbitrary angle. A groove (corresponding to the groove of the spray piece) 12a is formed from the upstream side to the downstream side. The lower end of the groove 12a is a groove outlet 12b of the spray piece. A space surrounded by the groove 12a and the tapered surface portion 11b of the valve body 11 becomes a slit, and the slit forming portion corresponds to the slit portion. Further, the guide 13 that supports the valve body 9 has an opening 13a for flowing fuel in the outer peripheral side depth portion.
The fuel injection valve 1 configured in this way opens and closes the fuel flow path by bringing the valve body 9 provided in the fuel flow path into and out of contact with the valve seat 11c, thereby completing the fuel injection / injection state. Yes, fuel is injected into the cylinder as a conical spray.

A bottom view of the valve body 11 and the spray piece 12 in FIG. 2 is shown in FIG. In this example, four grooves (inclined grooves) 12 a are formed at equal intervals on the tapered surface of the spray piece 12. Further, the spray piece groove 12a is formed in the tapered surface of the spray piece 12 as a spiral groove whose cross-sectional area increases toward the downstream side of the injection, and the groove outlet 12b of the spray piece which is the most downstream of the fuel flow path. Then, it is formed to have a length L and a groove depth W along the outer periphery.

Furthermore, the side view of the spray piece 12 is shown in FIG. The spray piece 12 having a substantially truncated cone shape has a height of about 2 mm and a diameter of a circle serving as a bottom surface of about 2 mm. In the side view of FIG. 4, with respect to the axis Lo passing through the center of the spray piece 12, the groove center line (inclined groove) 12a (groove center line) La are inclined by 10 °, the grooves 12a, the grooves The center line La is formed so as to be inclined (spiral) by a predetermined angle with respect to a plane passing through the axis Lo of the spray piece 12 . Furthermore, the inclination angle of the tapered surface of the spray piece 12 is 40 °.

Further, as shown in the top view of the spray piece 12 in FIG. 5, the length L1 at the upstream position and the length L2 at the downstream position of the groove 12a of the spray piece are formed so that the downstream side has a larger dimension. Specifically, L1 = 0.45 mm and L2 = 0.8 mm. The groove 12a is formed to have a depth (width) W = 0.15 mm.
Such a spray piece 12 is formed of stainless steel, and the groove 12a formed on the tapered surface (outer peripheral surface) of the truncated cone shape is processed by cutting. Cutting machining is relatively cheaper than electric discharge machining, and a spray piece can be manufactured at a low cost.

Next, the operation of the fuel injection valve configured as described above will be described.
When an operation signal is sent from the microcomputer of the engine to a drive circuit (not shown) of the fuel injection valve 1, a current is passed through the coil 5 of the fuel injection valve 1, and the housing 3, the core 4, and the amateur 10 are configured. Magnetic flux is generated in the magnetic circuit, and the amateur 10 is attracted to the core 4. The valve body 9 that is integral with the amateur 10 is separated from the seat portion 11a of the valve seat portion 11c, and when a gap is formed in this portion, high-pressure fuel with a fuel pressure of 2 MPa or more is supplied to the engine from the groove outlet 12b of the spray piece. The fuel is injected into the cylinder and fuel injection starts.

  The valve body 9 has its valve opening position determined when the upper end surface of the armature 10 with which the valve body 9 is integrated comes into contact with the lower end surface of the core 4, and fuel injection is continued for a few milliseconds to several milliseconds. After that, the energization to the coil is stopped by the off signal from the microcomputer, the electromagnetic force is reduced, and the valve body 9 starts to move in the valve closing direction by the force of the spring 6, and after several milliseconds for 10 minutes. Reaches the seat and the injection ends. FIG. 1 shows the fuel injection end state, and the gap between the upper end of the armature 10 and the lower end of the core 4 is actually about 0.05 mm (however, FIG. 1 is a drawing close to a scale). Therefore, it looks as if the upper end of the amateur 10 and the lower end of the core 4 are in contact.

  In the ON state of the valve body 9, the fuel that has flowed into the inner peripheral portion of the core 4 from the fuel supply pipe 15 passes through the gap between the armature 10 and the valve body 9 and reaches between the valve body 9 and the valve body 11 to guide The gap between the valve body 9 and the seat portion 11a is reached through the 13 openings 13a. The fuel further reaches the spray piece 12 through the gap between the valve body 9 and the valve seat portion 11c, and is injected into the engine cylinder from the groove outlet 12b through the groove 12a of the spray piece.

  FIG. 6 is a schematic cross-sectional view showing the fuel injection state. As shown in the figure, the fuel indicated by the fuel spray shape 30 is sprayed conically with a thin film at an injection angle of 60 ° from the groove outlet 12b into the cylinder. Moreover, as shown in the schematic diagram of the fuel spray shape 30 in FIG. 7, the fuel spray shape 30 seen on the surface separated by an arbitrary distance from the groove outlet 12b of the spray piece to the downstream side is on one circumference, A number of arcs corresponding to the number of grooves are arranged at equal intervals. As described above, the groove 12a of the spray piece has a cross-sectional shape similar to the slit shape, and the depth (width) W of the groove 12a is 0.15 mm, and the fuel form injected to the outside The so-called spray has a thin liquid film and is easily atomized. Further, since the length of the groove 12a increases in the downstream direction so that L1 = 0.45mm and L2 = 0.8mm, the spray spreads in the downstream direction. Atomization by is promoted.

By forming the groove (inclined groove) 12a of the spray piece 12a so that the groove center line La is inclined at a predetermined angle with respect to the plane passing through the axis Lo of the spray piece 12 (spiral shape) , the spray angle is changed to the spray piece. It becomes possible to make it larger than the taper angle of the outer peripheral surface of 12, and the spread angle of the spray completely independent of the cone angle of the spray piece 12 (inclination angle of the taper surface) can be made. The spread angle of the spray is determined depending on the cone angle of the spray piece 12 and the inclination angle of the spiral of the groove 12a, and the necessary spray spread angle can be obtained by adjusting these angles.

  Further, when the depth (width) of the groove 12a of the spray piece is constant and the length of the groove 12a is set to the length L1 = 100% at the upstream position, the length L2 = 120 to 300 at the downstream position. % Is suitable. When L2 is less than 120%, spray atomization deteriorates, and when it is more than 300%, spray atomization becomes good, but the spray shape becomes discontinuous and a stable spray shape cannot be obtained.

As described above, according to the fuel injection valve of the first embodiment of the present invention, when the groove 12a is formed in the spray piece 12, the machining can be performed by cutting, and the machining cost is lower than that of the electric discharge machining. It can be kept cheap.
In addition, the spray piece 12 having the same shape can be sprayed at different spray angles, and when producing models with different spray angles, the base shape of the spray piece and the valve body 11 become a common part, so the mass production effect is demonstrated. This makes it possible to keep costs low.

Embodiment 2.
Next, a second embodiment of the present invention will be described with reference to FIGS.
In the first embodiment described above, four grooves (inclined grooves) 12a are equally spaced on the tapered surface of the spray piece 12 , and the groove center line La passes through the axis Lo of the spray piece 12. An example in which it is formed so as to be inclined at a predetermined angle with respect to the above is shown. In the second embodiment, when a plurality of grooves are formed on the tapered surface of the spray piece 12, one groove is the same groove (inclined groove) 12a as in the first embodiment (corresponding to the first groove) . The other three grooves are grooves (corresponding to the second groove) formed so as to be located on a plane passing through the axis of the spray piece 12, that is, not in a spiral shape, but at an inclination angle of 0. It is formed as a groove (straight groove 12c) extending straight from the upstream to the downstream of the angle.

As shown in the schematic cross-sectional view showing the fuel injection state in FIG. 8, the fuel spray shape 30 sprayed from the groove outlet 12b of the groove 12a formed at an inclination (spiral inclination) angle of 10 ° and the straight line of the straight groove 12c. In the fuel spray state 31 sprayed from the groove outlet 12d, a difference occurs in the spray angle, and the larger the tilt (spiral tilt) angle, the wider the spray angle.
In addition, in FIG. 9, an inclination (spiral inclination) angle is shown as a schematic diagram showing a fuel spray shape seen on the surface separated from the groove outlet 12 b and the straight groove outlet 12 d of the spray piece by an arbitrary distance downstream. It can be seen that the fuel spray shape 30 having a larger is sprayed outward.

In this way, the technique of partially adjusting the spray angle by changing the inclination angle of the spiral for each groove can be applied, for example, when only the spray sprayed in the spark plug direction is desired to adjust the spray angle. it can.
According to the fuel injection valve of the second embodiment, it is possible to set sprays with different spray angles for the same product, and the correspondence to the spray shape required by the engine is enhanced.

Embodiment 3.
Next, a method for manufacturing a fuel injection valve according to the present invention will be described with reference to FIGS. FIG. 10 shows an enlarged cross-sectional view of a portion centering on the downstream portion of the fuel injection valve 1, the valve seat portion 11c and the spray piece 12, and FIG. 11 shows a bottom view thereof. As shown in FIGS. 10 and 11, in the state where the spray piece 12 is press-fitted or inserted into the valve seat portion 11 c of the valve body 11 from the downstream side, the downstream end face of the spray piece 12 and the downstream end face of the valve body 11 are The two are joined to each other by laser welding at a contact point on the surface. A joint by laser welding is shown as a laser weld 40. The laser welded portion 40 is provided between the adjacent grooves 12a, and two joining portions are provided in this example, but are adjusted by increasing / decreasing depending on the product.

When the spray piece 12 and the valve body 11 are to be joined, since the welded portion is very small, non-contact laser welding is suitable. For welding that requires contact, the position accuracy can be increased due to the restriction of the size of the welding rod. Is difficult and unsuitable.
Thus, fastening reliability can be improved by fastening the spray piece 12 and the valve main body 11 by laser welding.

It is sectional drawing which shows the structure of the fuel injection valve in Embodiment 1 of this invention. 1 is an enlarged cross-sectional view of a downstream end portion of a fuel injection valve in Embodiment 1 of the present invention. It is a fuel injection valve bottom view in Embodiment 1 of this invention. It is a side view of the spray piece in Embodiment 1 of this invention. It is a top view of the spray piece in Embodiment 1 of this invention. It is a schematic cross section which shows the fuel spray shape of the fuel injection valve in Embodiment 1 of this invention. It is a schematic diagram which shows the fuel spray shape in Embodiment 1 of this invention. It is a schematic cross section which shows the fuel spray shape of the fuel injection valve in Embodiment 2 of this invention. It is a schematic diagram which shows the fuel spray shape in Embodiment 2 of this invention. It is a fuel injection valve downstream end part expanded sectional view in Embodiment 3 of this invention. It is a fuel injection valve bottom view in Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Solenoid apparatus 3 Housing 4 Core 5 Coil 6 Spring 7 Rod 8 Valve apparatus 9 Valve body 10 Amateur 11 Valve main body 11a Seat part 11b Tapered surface part 11c Valve seat part 12 Spray piece 12a Spray piece groove 12b Spray piece Groove outlet 12c Linear groove 12d Linear groove outlet 13 Guide 13a Opening 14 Seal member 15 Fuel supply pipe 16 Washer 17 Fuel injection valve holder 18 Bobbin 19 Cylinder head 20 Terminal 21 Filter 22 Nylon mesh 23 Backup ring 24 O-ring 25 Ring 26 Valve Equipment parts 30, 31 Fuel spray shape 40 Laser welding part.

Claims (3)

A fuel injection valve that opens and closes the fuel flow path by bringing a valve body provided in the fuel flow path into and out of contact with the valve seat so that fuel injection / injection is completed. A substantially frustoconical spray piece having a tapered surface extending at an arbitrary angle toward the downstream side of injection from the seat portion in contact with the downstream side of the fuel flow path, and the valve seat is in contact with the tapered surface of the spray piece The tapered surface of the spray piece has a circumferential surface, and an inclined groove whose cross-sectional area increases toward the downstream side of the injection is formed, and the groove center line of the inclined groove is relative to a plane passing through the axis of the spray piece. The fuel injection valve is formed so as to be inclined at a predetermined angle, and the inclined groove is a part of the fuel flow path. First and second grooves are formed on the tapered surface of the spray piece, the first groove is the inclined groove , and the second groove has a substantially truncated cone shape. The fuel injection valve according to claim 1, wherein the fuel injection valve is a groove formed so as to be positioned on a plane passing through the fuel cell.   The method for manufacturing a fuel injection valve according to claim 1, further comprising the step of joining the spray piece to the valve seat by laser welding.

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