JP2004076640A - Armature for fuel injection valve and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an armature for fuel injection valve manufacturable at a low cost, which can ensure both the durability of a sliding guided part 21C and the magnetic property of a plate part 21B and solve the solid difference by the difference in attracting characteristic of the plate part 21B, and its manufacturing method. <P>SOLUTION: Paying attention to that at least the sliding guided part 21C has nonmagnetic property and durability, the plate part 21B possesses magnetic property, and a calburizing treatment or nitriding treatment for at least the sliding guided part 2C is limited to this part, this armature 21 has a rod part 21A, the plate part 21B attracted by a magnet core and a magnet, and the sliding guided part 21C. A nonmagnetic surface 44 having durability is formed on at least the sliding guided part 21C, and a magnetic surface 45 is formed on the plate part 21B. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an armature for a fuel injection valve and a method for manufacturing the same, and more particularly to an armature for a fuel injection valve that injects high pressure fuel supplied from an accumulator (common rail) or the like at a predetermined timing and a method for manufacturing the same. .
[0002]
[Prior art]
A conventional fuel injection valve will be outlined based on FIGS. 4 and 5.
FIG. 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 body), 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 a tip end thereof, and a high-pressure fuel introduction section 8 provided above the nozzle body 3. The back pressure control unit 7 is provided above the high pressure fuel introduction unit 8.
The fuel from the fuel tank 9 is increased in pressure by a fuel pump 10 and stored in a common rail 11 (accumulator), and high-pressure fuel is supplied to the fuel injection valve 1 from a high-pressure fuel introduction unit 8.
That is, a fuel passage 12 is formed from the high-pressure fuel introduction section 8 to the injector housing 2 and the nozzle body 3, so that high-pressure fuel can be supplied to the pressure receiving section 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 recirculation path 13 from the back pressure control part 7 so that the fuel can be recirculated to the fuel tank 9.
[0004]
An arbitrary number of fuel injection holes 14 are formed at the tip of the nozzle body 3, and the tip of the nozzle needle 4 is seated on a seat 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 for urging the nozzle needle 4 toward the seat portion 15 in the seat direction is provided above the nozzle needle 4, and a valve piston 5 integrated with the nozzle needle 4 is further extended upward.
[0006]
The valve body 6 has a control pressure chamber 17 formed in the upper central portion thereof, and the distal end of the valve piston 5 faces the control pressure chamber 17 from below.
The control pressure chamber 17 communicates with an introduction orifice 18 formed in the valve body 6. The introduction orifice 18 communicates with the fuel passage 12 and supplies the control pressure chamber 17 with the introduction pressure from the common rail 11.
[0007]
The control pressure chamber 17 also 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 controller 7.
The pressure receiving area of the top 5A of the valve piston 5 in the control pressure chamber 17 is larger than the pressure receiving area of the pressure receiving portion 4A 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 made of a magnetic material, and has 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 within an armature guide portion 24A as a skirt portion of the core mounting body 24.
Note that the armature guide portion 24A is simply fitted into the center hole 23A of the magnet core 23, not by press fitting.
The plate portion 21B forms a first gap L1 (lift amount) while maintaining a predetermined parallelism between the plate portion 21B and the distal end portion 24B of the armature guide portion 24A, and forms a predetermined gap between the plate portion 21B and the attraction surface 23B of the magnet core 23. To form the second gap L2.
[0010]
The magnet 22 accommodates this in the magnet accommodating portion 23C of the magnet core 23, generates a predetermined magnetic flux in the magnet core 23, and allows the armature 21 (plate portion 21B) to be attracted.
[0011]
The magnet core 23 is made of a magnetic material, and is integrated with the lower part 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 to 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 outwardly protruding portion 24D. The O-ring 27 is disposed between the core mounting body 24 and the upper protruding portion 2A of the injector housing 2. , A shim 28 is interposed between the main body and the injector housing 2.
The core mounting body 24 is made of a non-magnetic material, and its upper open portion 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. A 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 space 30 formed between the magnet core 23 and the injector housing 2 located on the outer peripheral side. The core mounting body 24 is fitted into the upper protruding portion 2A of the injector housing 2 so that the magnet core 23 It is possible to secure a radial adjustment allowance when setting the center 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 armature guide portion 24A and the center hole 23A of the magnet core 23. The magnetic leakage from the magnet core 23 can be reduced, and a relief portion for expansion of the armature guide portion 24A due to processing heat is formed.
[0016]
A radial slit 23E is formed in the magnet core 23 in the radial direction, and a communication passage 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 recirculation path 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 section 8 to the pressure receiving section 4A of the nozzle needle 4 via the fuel passage 12, and is controlled via the introduction-side orifice 18. The pressure is supplied to the top 5A of the valve piston 5 in the pressure chamber 17.
Therefore, the nozzle needle 4 receives the back pressure of the control pressure chamber 17 via the valve piston 5 and seats on the seat portion 15 of the nozzle body 3 together with the urging force of the nozzle spring 16 to close 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 portion 21B) against the urging force of the valve spring 25, and the valve ball 20 lifts to move 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 path 13 through the opening / closing orifice 19, and the high pressure acting on the top 5A of the valve piston 5 in the control pressure chamber 17 is released. Then, the nozzle needle 4 lifts from the seat portion 15 against the urging force of the nozzle spring 16 due to the high pressure of the pressure receiving portion 4A, releases the injection hole 14, and injects fuel.
When 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 the seat position (seat portion 15) via the valve piston 5. Then, the injection holes 14 are closed to terminate the fuel injection.
[0020]
However, when carburizing treatment is performed on the armature 21 to secure the durability of the sliding guided portion 21C that is guided in the axial direction in the armature guide portion 24A of the core mounting body 24, the plate portion 21B ( Similarly, carburizing is also performed on the suction surface), so that residual austenite is precipitated on the surface of the plate portion 21B.
Since this austenite has non-magnetic magnetic characteristics, a change occurs in the attraction characteristics between the magnet 22 and the magnet core 23, and as a result, the performance as the armature 21 varies (solid difference). There is a problem.
[0021]
On the other hand, there is concern that the sliding guided portion 21C may cause wear on the contact surface between the armature guide portion 24A due to generation of an attractive force due to its magnetization, and nonmagnetic magnetic properties are required. is there.
[0022]
FIG. 5 is an enlarged side view of the armature 21. A rod portion 21A and a sliding guided portion 21C of the armature 21 (portions indicated by parentheses in solid lines in the drawing) require non-magnetism and durability. 21B (portion indicated by a dotted line in parentheses in the figure) requires magnetism, and contradictory magnetic characteristics are required.
[0023]
In addition, as an electromagnetic valve using a disk-type armature, there is JP-A-2000-46244.
[0024]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an armature for a fuel injection valve and a method for manufacturing the same, which can ensure both durability of a sliding guided portion and magnetism of a plate portion. And
[0025]
Another object of the present invention is to provide an armature in a fuel injection valve which can eliminate a solid difference due to a difference in suction characteristics of a plate portion, and a method for manufacturing the same.
[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 an armature and a magnet or a magnet core, and a method of manufacturing the same.
[0027]
Further, the present invention provides an armature for a fuel injection valve which can be manufactured at low cost while ensuring the durability of a sliding guided portion, and can minimize the difference in suction characteristics of a plate portion, and a method of manufacturing the same. Make it an issue.
[0028]
[Means for Solving the Problems]
That is, in the present invention, at least the non-magnetic and durable portions are held in the slid guided portions, and the magnetism is retained in the plate portions, and at least the carburizing process or the nitriding process of the slid guided portions is limited here. The first invention is directed to a valve element capable of opening and closing a fuel injection hole, a rod part for driving the valve element, a plate part orthogonal to the rod part, and a plate part. 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 is provided. A durable non-magnetic surface is formed on the armature, and a magnetic surface is formed on the plate portion of the armature. Is an armature in the fuel injection valve.
[0029]
A second invention provides a valve element capable of opening and closing a fuel injection hole, a rod part for driving the valve element, a plate part orthogonal to the rod part, and a sliding guided part orthogonal to the plate part. And a magnet core and a magnet for attracting the plate portion of the armature, wherein the armature has a method for manufacturing an armature in a fuel injection valve, wherein the armature has durability at least at the sliding guided portion. A method of manufacturing an armature for a fuel injection valve, comprising: a nonmagnetic surface forming step of forming a certain nonmagnetic surface; and a magnetic surface forming step of 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 carburizing or nitriding the entire armature while forming the plate portion of the armature thick. Further, the magnetic surface forming step may include a plate portion processing step of deleting the nonmagnetic surface of the plate portion formed in the nonmagnetic processing step.
[0031]
As the non-magnetic surface forming step, after providing a plate portion mask for covering the plate portion of the armature, the entire armature is subjected to a carburizing process or a nitriding process to form the non-magnetic portion 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, but the armature directly controls the valve body. The present invention can be applied to any type of structure such as opening and closing control.
[0034]
In the armature and the method for manufacturing the same in the fuel injection valve according to the present invention, at least the non-magnetic and durable portions are held in the slidable guided portions, and the magnetism is retained in the plate portion, and the slidable guided portions are carburized or nitrided. Since the processing is limited to this, non-magnetic and durable parts are secured in the sliding guided part that guides the armature in the axial direction, the guiding function can be strengthened, and the plate part has suction. Characteristics can be secured stably, and the suction 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 dispersion between solids can be eliminated, and it can be manufactured at a low cost by a simple manufacturing method.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an armature in a fuel injection valve according to an embodiment of the present invention and a method for manufacturing the same 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 method of manufacturing the armature 21. First, as shown in FIG. 1A, an armature material 40 made of an iron material 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 covering the plate portion 21B with a predetermined thickness, and forms the plate portion 21B portion. Only the thickness is slightly thicker.
[0037]
As shown in FIG. 1 (2), the heating furnace 42 is filled with the carbon powder 43, is heated to a predetermined temperature, for example, 700 to 800 ° C., and is durable by carburizing (quenching) the entire armature material 40. The non-magnetic surface 44 having a property is formed (non-magnetic surface forming step, non-magnetic processing 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 has the same durability as in the case of carburization. A non-magnetic surface can be formed.
[0039]
FIG. 1C is a side view showing the armature material 40 in a carburized state, and is processed by removing a thick portion 41 which is a part of the nonmagnetic surface 44 (see FIG. 1C). The portion of the plate portion 21B is set as a magnetic surface 45 that can be attracted by the magnet 22 and the magnet core 23 (magnetic surface forming step, plate section 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 non-magnetic surface 44, and the plate portion 21B becomes a magnetic surface 45 not subjected to carburizing or nitriding. 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 the method of manufacturing an armature according to the present invention. In the case where the armature 21 is manufactured from a magnetic material, the plate portion 21B is covered with a plate portion mask 50, and a carburizing process is performed. 1 (2)) or a nitriding treatment (non-magnetic surface forming step).
[0042]
As the plate portion mask 50, a material such as a steel material which is less affected by carburizing treatment or nitriding treatment is selected. This is coated.
[0043]
According to such a manufacturing method as well, the rod portion 21A and the sliding guided portion 21C can be made the durable non-magnetic 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 method for manufacturing an armature according to the present invention. The armature 21 is made of a magnetic material, but has a non-durable non-durable portion on the rod portion 21A and the sliding guided portion 21C. It covers the magnetic coating 60 (non-magnetic surface forming step, coating step).
[0045]
As the coating treatment, a plating treatment, a plasma deposition method (PVD method), a chemical vapor deposition method (CVD method), or the like can be adopted.
[0046]
According to such a manufacturing method as well, the rod portion 21A and the sliding guided portion 21C can be made the durable non-magnetic surface 44 while maintaining the plate portion 21B 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 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 diagram 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 the method for producing an armature according to the present invention.
FIG. 4 is an enlarged sectional view of a main part of the fuel injection valve 1.
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 injector housing 2 Nozzle body 4 Nozzle needle (valve element)
4A Nozzle needle 4 pressure receiving section 5 Valve piston 5A Valve piston 5 top 6 Valve body 7 Back pressure control section 8 High pressure fuel introduction section 9 Fuel tank 10 Fuel pump 11 Common rail (accumulator)
Reference Signs List 12 fuel passage 13 fuel return passage 14 injection hole 15 seat 16 nozzle spring 17 control pressure chamber 18 introduction-side orifice 19 opening / closing orifice 20 valve ball (control valve body, valve body)
21 Armature 21A Rod part 21B of armature 21B Plate part 21C of armature 21 Sliding guided part 21D of armature 21 Radial slit 22 of armature 21 Magnet 23 Magnet core 23A Center hole 23B of magnet core 23B Attraction surface 23C of magnet core 23 Magnet accommodation part 23D of magnet core 23 Upper circumferential part 23E of magnet core 23 Radial slit 24 of magnet core 23 Core mounting body 24A Armature guide part 24B of core mounting body 24 Tip part 24C of armature guide part 24A Core mounting body 24 Lower peripheral portion 24D Outer projecting portion 25 of core mounting body 24 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 portion of plate portion 21B 42 Heating furnace 43 Carbon powder 44 Durable non-magnetic surface 45 Magnetic surface 50 Mask for plate portion (FIG. 2)
60 Durable non-magnetic coating (Figure 3)

Claims (5)

A valve body that can open and close the fuel injection hole,
An armature having a rod portion for driving the valve element, a plate portion orthogonal to the rod portion, and a sliding guided portion orthogonal to the plate portion;
A magnet core and a magnet for attracting the plate portion of the armature, and an armature in a fuel injection valve having:
While forming a durable non-magnetic surface on at least the sliding guided portion of the armature,
An armature in a fuel injection valve, wherein a magnetic surface is formed on the plate portion of the armature. A valve body that can open and close the fuel injection hole,
An armature having a rod portion for driving the valve element, a plate portion orthogonal to the rod portion, and a sliding guided portion orthogonal to the plate portion;
A magnet core and a magnet for attracting the plate portion of the armature, and a method for manufacturing an armature in a fuel injection valve having:
A non-magnetic surface forming step of forming a durable non-magnetic surface on at least the sliding guided portion of the armature;
A magnetic surface forming step of forming a magnetic surface on the plate portion of the armature,
A method for manufacturing an armature in a fuel injection valve, comprising: As the non-magnetic surface forming step,
The plate portion of the armature is formed thick, and a non-magnetic processing step of forming the non-magnetic surface by performing a carburizing process or a nitriding process on the entire armature,
As the magnetic surface forming step,
3. The method for manufacturing an armature in a fuel injection valve according to claim 2, further comprising a plate portion processing step of deleting said nonmagnetic surface of said plate portion formed in said nonmagnetic processing step. As the non-magnetic surface forming step,
After providing a plate portion mask for covering the plate portion of the armature, the non-magnetic surface is formed on the sliding guided portion by performing a carburizing process or a nitriding process on the entire armature. The method for producing an armature in a fuel injection valve according to claim 2. As the non-magnetic surface forming step,
3. The method for manufacturing an armature in a fuel injection valve according to claim 2, further comprising 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.

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