JPH0674124A - Fuel injection device and manufacture of fixed iron core thereof - Google Patents

Abstract

PURPOSE:To dissolve a factor that causes fuel leak by obviating a seal place by forming a fixed iron core which constitutes together with an electromagnetic coil an electromagnetic actuator for reciprocating a valve body, into integral structure having no joining place between a magnetic portion and a non-magnetic portion. CONSTITUTION:A fuel injection device reciprocates a valve body by means of an electromagnetic actuator consisting of a fixed iron core and an electromagnetic coil arranged in a casing, and feeds fuel into an internal combustion engine. The fixed iron core is provided with respective magnetic portions 12, 13 on both sides with a center nonmagnetic portion 11 interposed. In this instance, the fixed iron core is formed into integral structure having no joining place between the nonmagnetic portion 11 and the respective magnetic portions 12, 13. At the time of manufacture, firstly austenite stainless steel is processed into the shape of the fixed iron core in the range of a semi-stable austenite temperature not lower than a martensite transformation temperature. Next, magnetization is carried out by conducting processing and induction and transformation into a martensite phase, and then, the quality of the center portion is changed into the former non-magnetic austenite phase by means of heat processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for supplying fuel to an internal combustion engine, and more particularly to a structure of a fixed iron core of an electromagnetic actuator for reciprocally driving a valve body and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of an electronically controlled fuel injection device described in Japanese Patent Publication No. 58-54263. The electromagnetic actuator of the electronically controlled fuel injection device
Reciprocatingly drives a movable element 14 that is integrated with a stationary electromagnetic coil 10 and fixed iron cores 11, 12 and 13 that are arranged in a casing, and that is integrally formed with a valve body 15 that is coaxially opened with a gap. Let This fixed iron core has a magnetic part 1
2, 13 are divided into two, and the non-magnetic part 11 is provided in the middle part.
And the metal seals 16 and 17 are provided. The non-magnetic portion 11 increases the magnetic flux passing through the mover 14 in the magnetic circuit and improves the actuation response of the valve body. The conventional fixed iron core is composed of three members because the magnetic parts 12 and 13 and the non-magnetic part 11 are made of different magnetic materials and non-magnetic materials, respectively. The part of is sealed. As the sealing method, an O-ring seal is used in addition to the metal seal. The material of the fixed core is A
Stainless steel whose oxidation resistance is improved by 1 is used.

[0003]

The fixed iron core of the electromagnetic actuator of the conventional electronically controlled fuel injection device is composed of three members, and in order to assemble these three members with high accuracy, the respective parts have a fitting structure. You will need
There is a problem that the shape of the parts is complicated and high precision is required. Further, since a large number of highly accurate parts are required, there is a problem that the parts cost is high. Further, since it is composed of three members, it is necessary to use the O-ring seal and mechanical fixing at the same time, or fix them by welding. The fuel injection device operates at -30 ° C and +13 during operation.
Subject to severe temperature loading between 0 ° C. Therefore, the O-ring seal is deteriorated due to aging, shrinkage, curing, and especially the outflow of the softening agent due to the aromatic compound contained in gasoline, and the sealing property is deteriorated by repeated use. On the other hand, in the case of metal seals made by welding, if there are fine cracks or blowholes that cannot be detected by nondestructive inspection at the seal location, these defects grow through repeated use
The sealability may deteriorate. There is also a problem that the fuel under pressure may ignite by flowing out into the engine room through the above-mentioned location where the sealing property is deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a fixed iron core for an electromagnetic actuator of a fuel injection device which has a small number of parts and has no sealed portion.

Another object of the present invention is to provide a method of manufacturing a fixed iron core for an electromagnetic actuator, which can reduce the manufacturing cost.

[0006]

In the fuel injection device according to the present invention, the fixed iron core for an electromagnetic actuator is constructed as an integral structure having no joint between the magnetic part and the non-magnetic part. .

The fixed core is formed by subjecting an austenitic stainless steel to strong working in the shape of the fixed core in a metastable austenite temperature range above the martensitic transformation temperature, and subjecting it to work-induced transformation into a martensite phase to magnetize it, followed by heating. It is manufactured by modifying the intermediate portion to the original non-magnetic austenite phase by treatment.

The fixed iron core is made of non-magnetic austenite by locally melting and adding an austenite-forming element to magnetic steel made of an iron-chromium alloy, ferritic stainless steel, or martensitic stainless steel. It can also be produced by forming a phase in the middle part of the magnetic steel.

In addition, in the case where the non-magnetic portion is formed by melting and adding an austenite forming element to the material constituting the magnetic portion, the magnetic portion may be made of ferritic or martensitic stainless steel containing no Al. .

Further, in the fixed iron core, a ferrite-forming element is locally melted and added to a ferromagnetic iron-nickel alloy so that a non-magnetic austenite phase is added to an intermediate portion of the ferromagnetic iron-nickel alloy. It can also be manufactured by forming.

[0011]

In the present invention, since the fixed iron core for the electromagnetic actuator has an integral structure in which there is no joint between the magnetic portion and the non-magnetic portion, there is no seal portion and fuel leakage from the fixed iron core does not occur. A fuel injector that does not occur is obtained.

Further, since the fixed iron core is manufactured by magnetizing the material in the shape of the fixed iron core and then modifying the intermediate portion to the original non-magnetic state by the heat treatment, the fixed iron core is made of a single member. A one-piece structure having no points can be obtained, and the manufacturing cost can be significantly reduced by greatly simplifying the parts cost and the assembly process.

It is to be noted that the additive is locally melted and added to the magnetic steel in the shape of the fixed iron core to form a non-magnetic phase, thereby forming a non-magnetic phase. It is also possible to obtain a fixed iron core having no integral structure.

Further, in a magnetic steel having the shape of a fixed iron core, which is locally melt-added with an austenite-forming element to form a non-magnetic phase, the magnetic steel is ferritic or martensitic stainless containing no Al. By using steel, it is possible to obtain a fuel injection device in which cracks in the non-magnetic modified portion are eliminated and fuel does not leak from the core.

[0015]

【Example】

Example 1. FIG. 1 is a manufacturing process diagram of a fixed core for an electromagnetic actuator according to an embodiment of the present invention. First, the outer diameter 2
A non-magnetic austenitic stainless steel (SUS304) 1 (material) having a diameter of 0 mm, an inner diameter of 14 mm and a length of 50 mm is prepared. The stainless steel is forged at 250 ° C. into a fixed iron core having an outer diameter of 18 mm and an inner diameter of 16 mm.
Immediately after processing, the processed product at 250 ° C is treated with NaC at -20 ° C.
Quench in 1 aqueous solution (22.4 wt%) 2. By the above treatment, the austenitic stainless steel undergoes work-induced martensitic transformation and becomes ferromagnetic. Next, the CO2 laser 3 is irradiated to the nonmagnetic portion forming portion, and the nonmagnetic portion forming portion is locally heated to 900 to 1300 ° C. The heated portion 4 changes from a martensite structure to an austenite structure and becomes nonmagnetic.

By the above processing, the structure and magnetism of the austenitic stainless steel processed into the shape of the fixed iron core are as shown in FIG. 2, and the fixed portion having the non-magnetic portion 11 in the middle portion of the ferromagnetic portions 12 and 13 is obtained. The iron core can be formed of an integral structure having no joint between the ferromagnetic portion and the non-magnetic portion.

Although SUS304 is used as the non-magnetic austenitic stainless steel in the above-mentioned embodiment, it should be determined according to the required material characteristics to be used for it, and is not limited to this embodiment. Not a thing. Further, the material and the shape of the fixed core may be appropriately determined.

Further, the processing method and the processing conditions of the fixed iron core should be determined according to the magnetic permeability required for the ferromagnetic portion of the fixed iron core, and are not limited to this embodiment.

Although a CO 2 laser is used as the heating heat source, a YAG laser, an excitation beam such as an electron beam can also be used, and the present invention is not limited to this embodiment. Moreover, the irradiation condition of the excitation beam and the rotation speed of the work should be determined according to the magnetic permeability required for the non-magnetic portion of the fixed iron core, and are not limited to the present embodiment.

Example 2. FIG. 3 shows a manufacturing process drawing of a fixed core for an electromagnetic actuator according to another embodiment of the present invention. First, outer diameter 18 mm, inner diameter 16 mm, length 50 mm
Magnetic Ferritic Stainless Steel (SUS405) 1
(Material) and a Ni wire 1 mm in diameter (purity 99.9% or more) 5 are prepared. Next, rotate the stainless steel 1 at a rotation speed of 4 r
Outputs CO2 laser 3 at 1.5k while rotating at pm
Irradiate the center of the outer surface once with W and ab values of 1, and then N
Supply the i-wire 5. The laser irradiation portion produces a fusion zone 6 having a width of 2 mm and a depth of 1 mm in the laser movement direction,
Ni is uniformly dispersed in the fusion zone. After the laser irradiation, the melted portion 6 is solidified, and only the melted portion changes into an austenite structure and becomes non-magnetic. By the above processing, the magnetism of the fixed iron core becomes a structure having non-magnetism in the intermediate portion of the magnetic portion.

Example 3. FIG. 4 shows a manufacturing process drawing of a fixed core for an electromagnetic actuator which is still another embodiment of the present invention. First, outer diameter 18 mm, inner diameter 16 mm, length 50
Prepare a ferromagnetic permalloy B1 (material) of mm. Next, the entire surface of the permalloy B is Cr with a thickness of 0.13 mm.
Apply plating 7. Furthermore, permalloy B is rotated at 4 rp
Outputs CO2 laser 3 1.5k while rotating at m
Irradiate the center of the outer surface once with W and ab values of 1. At the laser irradiation portion, a melted portion 6 having a width of 2 mm and a depth of 1 mm is generated in the laser moving direction, and Cr is uniformly dispersed in the melted portion. After laser irradiation, the melted portion 6 solidifies, and the melted portion 6 is Fe-
It becomes a 17 wt% Cr-35 wt% Ni alloy, and the structure is austenite single phase and non-magnetic. By the above processing,
The magnetism of the fixed iron core has a non-magnetic structure in the middle part of the ferromagnetic part.

Although the ferritic stainless steel (SUS405) is used in the second embodiment, an iron-chromium alloy or a martensitic stainless steel may be used, and the material used in the third embodiment is also It should be determined according to the required material characteristics to be used for it, and is not limited to this example. Needless to say, the composition of the non-magnetic portion is not limited to that of this embodiment as long as it is in the austenite forming region.

Example 4. In the case where the magnetic part is made of stainless steel whose Al is made of Al and has improved oxidation resistance, the low melting point Al is a non-magnetic austenite crystal grain boundary in the product manufactured by the manufacturing method shown in the second embodiment. Segregates to cause cracks as shown in FIG. 5 (a), and fuel under pressure flows through the cracks into the engine room, causing a new problem such as ignition. In this embodiment, the magnetic part of the iron core is made of stainless steel containing no Al or stainless steel whose oxidation resistance is improved by Si instead of Al, and a portion of which is locally added with an austenite-forming element by melting. By doing so, since the non-magnetic reforming is performed, cracks in the non-magnetic reforming portion are eliminated, and a fuel injection device in which fuel leakage from the core does not occur can be obtained.

The material of the magnetic part of this embodiment is SUS.
410L, SUS430, SUS434 and the like, Cr is 10 to 35%, Si is 4% or less, C is 0.15% or less,
Other Mn, P, S, Mo, N, Ni, C as required
ferritic stainless steel containing u and the like and not containing Al, or SUS403, SUS410,
Cr such as SUS416 is 10 to 20%, Si is 2%
Hereinafter, C is 1.5% or less, and if necessary, Mn,
An example of the martensitic stainless steel contains P, S, Ni, Mo, etc. and does not contain Al.

A method of manufacturing an iron core whose magnetic portion is made of SUS410L will be described below. First, by processing such as cutting, cold forging, and cutting, the outer diameter is 10 mm, the inner diameter is 8 mm, and the length is 50 m.
A raw material (SUS410L) processed into a m-shaped pipe and a Ni wire (purity 99.9 or more) having a diameter of 0.35 mm are prepared. Next, use SUS410L to rotate 32r
Outputs a CO2 laser of 1.5k while rotating at pm
Irradiate the center of the outer surface once with W and ab values of 1, and then N
Supply i-wire. The laser irradiation portion produces a melted portion having a width of 2 mm and a depth of 1 mm in the laser moving direction, and Ni is uniformly dispersed in the melted portion. After the laser irradiation, the melted portion is solidified, and only the melted portion changes into an austenite structure and becomes non-magnetic. Through the above processing, the core has a structure having a non-magnetic modified portion in the middle portion of magnetic stainless steel.

The magnetic permeability of the non-magnetic portion obtained by the above method was measured by a magnetic balance method and the result was 1.1 or less. In addition, SUS405, whose magnetic material is Al, has improved oxidation resistance.
5 (a) that occurred when non-magnetic modification was performed using
As shown in FIG. 5 (b), the cracks shown in FIG.
It was not observed when 410L was non-magnetically modified.

The material and the shape of the fixed iron core in each of the above embodiments may be appropriately determined. Further, the range of the non-magnetic part may be appropriately determined in the same manner.

Further, although a CO 2 laser is used as the heating heat source, an excitation beam such as a YAG laser or an electron beam, an arc or a plasma can be used, and the present invention is not limited to the above-mentioned embodiments. Further, the irradiation condition of the excitation beam and the rotation speed of the work should be determined according to the magnetic permeability required for the non-magnetic portion of the fixed iron core, and are not limited to the above-mentioned respective embodiments.

Further, in Examples 2 and 4 above, Ni was used as the austenite forming element.
n and Cu can also be used, and the present invention is not limited to this example.

Although a Ni wire having a purity of 99.9% or more is used, a wire made of an alloy containing an austenite-forming element such as a Ni-Cr alloy or a Ni-Cu alloy can also be used, and is limited to this embodiment. It is not something that will be done. Also,
The diameter of the wire is determined according to the composition of the non-magnetic portion, and is not limited to this embodiment.

Further, in the above-mentioned Embodiments 2 and 4, the wire supply method is used as the Ni addition method, but the plating method and the powder supply method can also be used, and the present invention is not limited to this embodiment. Similarly, although the plating method is used as the Cr addition method in the third embodiment, the present invention is not limited to this embodiment.

[0032]

As described above, according to the present invention, the fixed core for the electromagnetic actuator is constructed as an integral structure having no joint between the magnetic portion and the non-magnetic portion. Is eliminated, the factor that causes fuel leakage from the fixed core for the electromagnetic actuator is eliminated, and the reliability of the fuel injection device is significantly improved.

The fixed iron core is formed by subjecting austenitic stainless steel to strong working in the shape of the fixed iron core in the metastable austenite temperature range above the martensitic transformation temperature,
It was manufactured by transforming the intermediate part to the original non-magnetic austenite phase by heat treatment after processing-induced transformation to the martensite phase to make it magnetized. In addition, the number of parts of the fixed iron core can be reduced from three to one, and the manufacturing cost can be significantly reduced by greatly simplifying the parts cost and the assembly process.

The fixed iron core is obtained by locally melting and adding an austenite-forming element to a magnetic steel made of an iron-chromium alloy, a ferritic stainless steel, or a martensitic stainless steel by using an excitation beam or the like as a heat source. Alternatively, the melted portion may be manufactured as a non-magnetic austenite single phase, and as in the above-described manufacturing method, an integrated structure having one member and no sealing portion can be obtained. There is an effect that the manufacturing cost can be significantly reduced due to the reduction in the body and the simplification of the parts cost and the assembly process.

By using a ferritic or martensitic stainless steel containing no Al as the magnetic steel, a fuel injection device is obtained in which cracks in the non-magnetic reformed portion are eliminated and fuel leakage from the core does not occur. It is effective.

Further, the fixed iron core is made of a ferromagnetic Fe--
A ferrite-forming element such as Cr may be locally melt-added to a Ni alloy steel by using an excitation beam as a heat source, and the melted portion may be manufactured as a non-magnetic austenite single phase, which has the same effect as the above manufacturing method.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a fixed core for an electromagnetic actuator showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a fixed core for an electromagnetic actuator according to the first embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of a fixed core for an electromagnetic actuator showing a second embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of a fixed core for an electromagnetic actuator showing a third embodiment of the present invention.

FIG. 5 is a photograph showing a nonmagnetic modified portion in Examples 2 and 4 of the present invention.

FIG. 6 is a cross-sectional view showing an electronically controlled fuel injection device.

[Explanation of symbols]

 1 Material 3 CO2 Laser Beam 4 Heating Part 5 Ni Wire 6 Melting Part 7 Cr Plating Layer 10 Electromagnetic Coil 11 Non-Magnetic Part 12 Ferromagnetic Part 13 Ferromagnetic Part 14 Mover 15 Valve Body

Claims (5)

[Claims] 1. An electromagnetic coil arranged in a casing,
And a fuel injection device that supplies fuel to an internal combustion engine by reciprocatingly driving a valve element by an electromagnetic actuator composed of fixed iron cores having magnetic portions on both sides with a non-magnetic portion interposed therebetween. A fuel injection device having an integral structure having no joint between the nonmagnetic portion and the nonmagnetic portion. 2. Austenitic stainless steel is subjected to strong working in the shape of a fixed core in a metastable austenite temperature range above the martensitic transformation temperature, and is subjected to work-induced transformation into a martensite phase to be magnetized and then subjected to heat treatment to form an intermediate. Method for manufacturing a fixed iron core of a fuel injection device, which reforms a non-magnetic austenite phase based on a part. 3. A non-magnetic austenite phase is added to a magnetic steel composed of an iron-chromium alloy, a ferritic stainless steel, or a martensitic stainless steel by locally melting and adding an austenite-forming element. Of manufacturing a fixed iron core of a fuel injection device, which is formed in the middle part of the. 4. The method for manufacturing a fixed core of a fuel injection device, wherein the magnetic steel according to claim 3 is made of ferritic stainless steel containing no Al or martensitic stainless steel. 5. A fuel injection device for locally adding a ferrite-forming element to a ferromagnetic iron-nickel alloy to add a non-magnetic austenite phase to an intermediate portion of the ferromagnetic iron-nickel alloy. Method of manufacturing fixed iron core.