JP3790991B2 - Method for manufacturing armature in fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an armature in a fuel injection valve and a manufacturing method thereof, and more particularly to an armature in a fuel injection valve that injects high-pressure fuel supplied from a pressure accumulator (common rail) at a predetermined timing and a manufacturing method thereof. .
[0002]
[Prior art]
A conventional fuel injection valve will be outlined with reference to FIGS.
4 is an enlarged cross-sectional view of a main part of the fuel injection valve 1. The fuel injection valve 1 includes an injector housing 2, a nozzle body 3, a nozzle needle 4 (valve element), a valve piston 5, and a valve body. 6 and a back pressure control unit 7.
[0003]
The injector housing 2 is provided with a nozzle body 3 at its tip and a high-pressure fuel introduction part 8 at the upper part thereof. The back pressure control unit 7 is provided above the high pressure fuel introduction unit 8.
The fuel from the fuel tank 9 is made high pressure by the fuel pump 10 and stored in the common rail 11 (pressure accumulator), and the high pressure fuel is supplied from the high pressure fuel introduction part 8 to the fuel injection valve 1.
That is, a fuel passage 12 is formed from the high pressure fuel introduction part 8 to the injector housing 2 and the nozzle body 3 so that the high pressure fuel can be supplied to the pressure receiving part 4A of the nozzle needle 4. Further, a part of the fuel passage 12 is extended upward in FIG. 4 from the high-pressure fuel introduction part 8 to form a fuel return passage 13 from the back pressure control part 7 so that the fuel can be returned to the fuel tank 9.
[0004]
The nozzle body 3 is formed with an arbitrary number of fuel injection holes 14 at the tip thereof, and the tip of the nozzle needle 4 is seated on the sheet portion 15 connected to the injection hole 14 to close the injection hole 14. When the needle 4 is lifted from the seat portion 15, the injection hole 14 is opened and fuel can be injected.
[0005]
A nozzle spring 16 that urges the nozzle needle 4 in the seat direction toward the seat portion 15 is provided above the nozzle needle 4, and a valve piston 5 that is integral with the nozzle needle 4 extends further upward.
[0006]
The valve body 6 forms a control pressure chamber 17 at the upper center portion thereof, and the tip end portion of the valve piston 5 is made to face the control pressure chamber 17 from below.
The control pressure chamber 17 communicates with an introduction-side orifice 18 formed in the valve body 6. The introduction side orifice 18 communicates with the fuel passage 12 and supplies the introduction pressure from the common rail 11 to the control pressure chamber 17.
[0007]
The control pressure chamber 17 communicates with an opening / closing orifice 19, and the opening / closing orifice 19 can be opened and closed by a valve ball 20 (control valve body, valve body) of the back pressure control unit 7.
Note that the pressure receiving area of the top portion 5 </ b> A of the valve piston 5 in the control pressure chamber 17 is larger than the pressure receiving area of the pressure receiving portion 4 </ b> A of the nozzle needle 4.
[0008]
The back pressure control unit 7 controls the lift operation of the nozzle needle 4 by controlling the pressure in the control pressure chamber 17 (that is, the back pressure of the nozzle needle 4). , An armature 21, a magnet 22, a magnet core 23, a core mounting body 24, a valve spring 25, and the control pressure chamber 17 described above.
[0009]
The armature 21 is composed of a magnetic material, and includes a rod portion 21A having a valve ball 20, a plate portion 21B orthogonal to the rod portion 21A, and a sliding guided portion orthogonal to the plate portion 21B. 21C, and the sliding guided portion 21C can be slidably guided in the axial direction in the armature guide portion 24A as the skirt portion of the core mounting body 24.
Note that the armature guide portion 24A is not press-fitted into the center hole 23A of the magnet core 23 but simply fitted.
The plate portion 21B forms a first gap L1 (lift amount) while maintaining a predetermined parallelism with the distal end portion 24B of the armature guide portion 24A, and a predetermined gap between the plate portion 21B and the suction surface 23B of the magnet core 23. The second gap L2 is formed while maintaining the parallelism.
[0010]
The magnet 22 is housed in the magnet housing portion 23C of the magnet core 23, generates a predetermined magnetic flux in the magnet core 23, and can attract the armature 21 (plate portion 21B).
[0011]
The magnet core 23 is composed of a magnetic material, and is integrated with the lower portion of the core mounting body 24 by laser welding or the like.
That is, by welding the upper circumferential portion 23D (fixed end) of the magnet core 23 at the lower circumferential portion 24C of the core mounting body 24, the core mounting body 24 and the magnet core 23 are integrated with each other.
[0012]
The core mounting body 24 is attached to the injector housing 2 by a retaining nut 26 that engages with the outward projecting portion 24D, and an O-ring 27 is disposed between the upper projecting portion 2A of the injector housing 2 and the core mounting body 24. The shim 28 is interposed between the injector housing 2 and the main body.
The core mounting body 24 is made of a non-magnetic material, and the upper open portion thereof is closed by a plug 29.
[0013]
The magnet core 23 is cantilevered at its upper circumferential portion 23D and is integrated with the core mounting body 24. The suction surface 23B opposite to the upper circumferential portion 23D is a free end. The armature 21 (plate portion 21B) faces the free end (suction surface 23B) in parallel.
[0014]
The magnet core 23 has a first annular gap 30 formed between the magnet housing 23 and the injector housing 2 located on the outer peripheral side thereof. The core mounting body 24 is fitted into the upper projecting portion 2A of the injector housing 2 to It is possible to secure a radial adjustment margin when setting the central axis.
[0015]
A part of the outer peripheral surface of the armature guide portion 24A is cut in the radial direction to make this portion thin, and a second annular gap 31 is formed between the central hole 23A of the magnet core 23, and the armature guide portion 24A is In addition, it is possible to reduce magnetic leakage from the interposed magnet core 23, and an escape portion for expansion due to processing heat of the armature guide portion 24A is formed.
[0016]
A radial slit 23E is formed in the magnet core 23 in the radial direction, and a communication path 32 communicating with the radial slit 23E is formed in the core mounting body 24.
[0017]
Therefore, the passage from the armature chamber 33 to the communication passage 32 is formed by the formation of the radial slit 23E together with the passage from the armature chamber 33 to the fuel return passage 13 through the opening / closing orifice 19 from the control pressure chamber 17. .
[0018]
In the fuel injection valve 1 having such a configuration, the high-pressure fuel from the common rail 11 is supplied from the high-pressure fuel introduction portion 8 to the pressure receiving portion 4A of the nozzle needle 4 via the fuel passage 12 and is controlled via the introduction-side orifice 18. The pressure chamber 17 is supplied to the top 5 </ b> A of the valve piston 5.
Therefore, the nozzle needle 4 receives the back pressure of the control pressure chamber 17 via the valve piston 5, seats on the seat portion 15 of the nozzle body 3 together with the urging force of the nozzle spring 16, and closes the injection hole 14. ing.
[0019]
By supplying a drive signal to the magnet 22 at a predetermined timing, the magnet 22 attracts the armature 21 (plate part 21B) against the urging force of the valve spring 25, and the valve ball 20 lifts to open and close the opening / closing orifice 19. When released, the high pressure in the control pressure chamber 17 returns to the fuel tank 9 through the fuel return passage 13 via the opening / closing orifice 19, so that the high pressure acting on the top 5A of the valve piston 5 in the control pressure chamber 17 is released. The nozzle needle 4 is lifted from the seat portion 15 against the urging force of the nozzle spring 16 by the high pressure of the pressure receiving portion 4A, and the fuel is injected by releasing the injection hole 14.
If the valve ball 20 closes the opening / closing orifice 19 by demagnetizing the magnet 22, the pressure in the control pressure chamber 17 causes the nozzle needle 4 to seat at its seat position (seat portion 15) via the valve piston 5. Then, the injection hole 14 is closed and the fuel injection is terminated.
[0020]
However, when carburizing treatment is performed on the armature 21 and the durability of the sliding guided portion 21 </ b> C guided in the axial direction in the armature guide portion 24 </ b> A of the core mounting body 24 in particular, the plate portion 21 </ b> B ( Since the carburization is similarly performed on the suction surface, residual austenite is deposited on the surface of the plate portion 21B.
Since this austenite has non-magnetic magnetic characteristics, the attraction characteristics between the magnet 22 and the magnet core 23 change, resulting in a variation in performance (solid difference) as the armature 21. There is a problem.
[0021]
On the other hand, in particular, the sliding guided portion 21C is worried that it may cause wear on the contact surface with the armature guide portion 24A due to the generation of an attractive force due to its magnetization, and nonmagnetic magnetic characteristics are required. is there.
[0022]
FIG. 5 is an enlarged side view of the armature 21, and the rod portion 21 </ b> A and the sliding guided portion 21 </ b> C (portion indicated by a solid line in the drawing) require non-magnetic properties and durability. 21B (the part indicated by the dotted parentheses in the figure) requires magnetism and requires mutually opposite magnetic characteristics.
[0023]
As an electromagnetic valve using a disk-type armature, there is JP 2000-46244.
[0024]
[Problems to be solved by the invention]
The present invention has been considered in view of the above problems, and it is an object of the present invention to provide an armature in a fuel injection valve and a method of manufacturing the same that can ensure both durability of a sliding guided portion and magnetism of a plate portion. And
[0025]
Moreover, this invention makes it a subject to provide the armature in the fuel injection valve which can eliminate the solid difference by the difference in the suction characteristic of a plate part, and its manufacturing method.
[0026]
Another object of the present invention is to provide an armature in a fuel injection valve capable of stabilizing the performance as a fuel injection valve by improving the magnetic force by the armature and the magnet or magnet core, and a manufacturing method thereof.
[0027]
The present invention also provides an armature in a fuel injection valve that can be manufactured at low cost while ensuring the durability of the sliding guided portion, and can eliminate the difference in suction characteristics of the plate portion as much as possible, and a method for manufacturing the same. Let it be an issue.
[0028]
[Means for Solving the Problems]
That is, the present invention restricts at least the sliding guided portion to be non-magnetic and durable, the plate portion to have magnetism, and at least carburizing treatment or nitriding treatment to the sliding guided portion. In the first invention, a valve body capable of opening and closing a fuel injection hole, a rod portion for driving the valve body, a plate portion orthogonal to the rod portion, and the plate portion An armature in a fuel injection valve having an armature having an orthogonal sliding guided portion and a magnet core and a magnet for attracting the plate portion of the armature, wherein at least the sliding guided portion of the armature In addition, a durable non-magnetic surface is formed and a magnetic surface is formed on the plate portion of the armature. Is an armature in the fuel injection valve.
[0029]
The second invention is a valve body capable of opening and closing a fuel injection hole, a rod portion for driving the valve body, a plate portion orthogonal to the rod portion, and a sliding guided portion orthogonal to the plate portion. And a magnet core and a magnet for attracting the plate portion of the armature, and a method for manufacturing the armature in the fuel injection valve, wherein at least the sliding guided portion of the armature is durable. A method for manufacturing an armature in a fuel injection valve, comprising: a nonmagnetic surface forming step for forming a certain nonmagnetic surface; and a magnetic surface forming step for forming a magnetic surface on the plate portion of the armature.
[0030]
The non-magnetic surface forming step includes a non-magnetic processing step of forming the non-magnetic surface by forming the plate portion of the armature thick and carburizing or nitriding the entire armature. In addition, the magnetic surface forming step can include a plate portion processing step of deleting the nonmagnetic surface of the plate portion formed in the nonmagnetic processing step.
[0031]
In the nonmagnetic surface forming step, a mask for the plate portion that covers the plate portion of the armature is provided, and then the entire armature is subjected to carburizing treatment or nitriding treatment to thereby form the nonmagnetic surface on the sliding guided portion. A surface can be formed.
[0032]
The non-magnetic surface forming step may include a coating step of forming the non-magnetic surface by coating at least the sliding guided portion of the armature with a non-magnetic material.
[0033]
The control structure of the valve body (nozzle needle 4) by the armature is not limited to the indirect structure via the back pressure control unit 7 as in the fuel injection valve 1 shown in FIG. 4, and the armature directly controls the valve body. The present invention can be applied to any type of structure such as opening / closing control.
[0034]
In the armature in the fuel injection valve according to the present invention and the manufacturing method thereof, at least the sliding guided portion is made non-magnetic and durable, and the plate portion is magnetized so that the sliding guided portion is carburized or nitrided. Since the processing is limited to this, the sliding guided part that guides the armature in the axial direction is non-magnetic and durable, and its guiding function can be strengthened, while the plate part is sucked. The characteristics can be stably secured and the attraction function between the magnet and the magnet core can be enhanced.
Therefore, the performance as an armature or a fuel injection valve can be stabilized, the variation between solids can be eliminated, and it can be manufactured at a low cost by a simple manufacturing method.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Next, an armature in a fuel injection valve according to an embodiment of the present invention and a manufacturing method thereof will be described with reference to FIG. However, the same parts as those in FIGS. 4 and 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.
FIG. 1 is an explanatory view showing each step of the manufacturing method of the armature 21. First, as shown in FIG. 1 (1), an armature material 40 made of iron or other magnetic material is prepared.
[0036]
The armature material 40 has substantially the same size and shape as the armature 21 as the final product, but forms a thick portion 41 that covers the plate portion 21B with a predetermined thickness, and the plate portion 21B portion. Only a little thick.
[0037]
As shown in FIG. 1 (2), the heating furnace 42 is filled with the carbon powder 43 and heated to a predetermined temperature, for example, 700 to 800 ° C., and the entire armature material 40 is carburized (quenched) to be durable. A non-magnetic surface 44 having a characteristic is formed (a non-magnetic surface forming step, a non-magnetic treatment step).
[0038]
If heating is performed in a state where the heating furnace 42 is filled with nitrogen gas instead of the carbon powder 43, the entire armature material 40 can be nitrided, and is durable as in the case of carburizing. A nonmagnetic surface can be formed.
[0039]
FIG. 1 (3) is a side view showing the armature material 40 in a carburized state, and is processed by removing the thick portion 41 which is a part of the nonmagnetic surface 44 (FIG. 1). A portion of the plate portion 21B is a magnetic surface 45 that can be attracted by the magnet 22 and the magnet core 23 (magnetic surface forming step, plate portion processing step).
This processing thickness is about 0.3 to 0.4 mm.
[0040]
Thus, as shown in FIG. 1 (4), the sliding guided portion 21C and the rod portion 21A become a durable nonmagnetic surface 44, and the plate portion 21B becomes a magnetic surface 45 that has not been subjected to carburizing or nitriding treatment. Then, the sliding guided portion 21C and the rod portion 21A are polished and annealed to obtain a final product.
[0041]
FIG. 2 is an explanatory view showing another example of a method for manufacturing an armature according to the present invention, in which a plate portion mask 50 is coated on a plate portion 21B of an armature 21 made of a magnetic material, and carburizing treatment (FIG. 1 (2)) or nitriding treatment (non-magnetic surface forming step).
[0042]
As the plate portion mask 50, a material such as a steel material that is less affected by carburizing or nitriding treatment is selected. This is coated.
[0043]
Even with such a manufacturing method, the rod portion 21A and the sliding guided portion 21C can be made the durable nonmagnetic surface 44 while the plate portion 21B is maintained on the magnetic surface 45.
[0044]
FIG. 3 is an explanatory view showing still another example of the manufacturing method of the armature according to the present invention. The rod portion 21A and the sliding guided portion 21C of the armature 21 made of a magnetic material are durable. The magnetic coating 60 is coated (non-magnetic surface forming process, coating process).
[0045]
As this coating process, a plating process, a plasma vapor deposition method (PVD method), a chemical vapor deposition method (CVD method), or the like can be employed. For example, a carbon coating, a ceramic coating, a diamond-like coating (DLC), or the like is coated.
[0046]
Even with such a manufacturing method, the rod portion 21A and the sliding guided portion 21C can be made the durable nonmagnetic surface 44 while the plate portion 21B is maintained on the magnetic surface 45.
[0047]
【The invention's effect】
As described above, according to the present invention, the sliding guided portion can be made durable and non-magnetic while maintaining the magnetic function of the plate portion. Characteristics can be secured.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing each step of a method for manufacturing an armature 21 in a fuel injection valve according to an embodiment of the present invention.
FIG. 2 is an explanatory view showing another example of a method for manufacturing an armature according to the present invention.
FIG. 3 is an explanatory view showing still another example of a method for manufacturing an armature according to the present invention.
4 is an enlarged cross-sectional view of a main part of the fuel injection valve 1. FIG.
FIG. 5 is an enlarged side view of the armature 21. FIG.
[Explanation of symbols]
1 Fuel injection valve (Fig. 4)
2 Injector housing 2A Upper protrusion 3 of the injector housing 2 Nozzle body 4 Nozzle needle (valve element)
4A Pressure receiving portion 5 of nozzle needle 4 Valve piston 5A Top portion 6 of valve piston 5 Valve body 7 Back pressure control portion 8 High pressure fuel introduction portion 9 Fuel tank 10 Fuel pump 11 Common rail (pressure accumulator)
12 Fuel passage 13 Fuel return passage 14 Injection hole 15 Seat portion 16 Nozzle spring 17 Control pressure chamber 18 Introducing orifice 19 Opening / closing orifice 20 Valve ball (control valve body, valve body)
21 Armature 21A Rod portion 21B of armature 21 Plate portion 21C of armature 21 Sliding guided portion 21D of armature 21 Radial slit 22 of armature 21 Magnet 23 Magnet core 23A Center hole 23B of magnet core 23 Attraction surface 23C of magnet core 23 Magnet housing portion 23D of magnet core 23 Upper circumferential portion 23E of magnet core 23 Radial slit 24 of magnet core 23 Core mounting body 24A Armature guide portion 24B of core mounting body 24 Tip portion 24C of armature guide portion 24A Core mounting body 24 Lower circumferential portion 24D of the core mounting body 24 outwardly projecting portion 25 valve spring 26 retaining nut 27 O-ring 28 shim 29 plug 30 first annular gap 31 2 of the annular space 32 communicating path 33 armature chamber 40 Armature material (Fig. 1)
41 Thick part 42 of plate part 21B Heating furnace 43 Carbon powder 44 Durable nonmagnetic surface 45 Magnetic surface 50 Plate part mask (FIG. 2)
60 Durable non-magnetic coating (Figure 3)

Claims (1)

A control valve body for opening and closing a control pressure chamber for controlling a back pressure of a nozzle needle capable of opening and closing a fuel injection hole ;
An armature having a rod portion for driving the control valve body , a plate portion orthogonal to the rod portion, and a sliding guided portion orthogonal to the plate portion;
The magnet core and the magnet for attracting the plate portion of the armature, the possess,
A method for manufacturing an armature in a fuel injection valve , wherein the pressure in the control pressure chamber is controlled by the control valve body to enable the nozzle needle to open and close the injection hole ,
A nonmagnetic surface forming step of forming a durable nonmagnetic surface on at least the sliding guided portion of the armature;
Forming a magnetic surface on the plate portion of the armature; and
And it has a,
As the non-magnetic surface forming step,
The plate portion of the armature is formed thick and has a non-magnetic treatment step of forming the non-magnetic surface by carburizing or nitriding the entire armature,
As the magnetic surface forming step,
A method for manufacturing an armature in a fuel injection valve , comprising: a plate portion machining step for deleting the nonmagnetic surface of the plate portion formed in the nonmagnetic treatment step .

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