JP2013160083A - Electromagnetic fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: in a weld portion of a nozzle tube and a stationary core, during the process of re-solidification of a molten metal in a welding process, vapors created by vaporization of a lubricant can flow along a molten metal surface in the weld portion from a pressure fitting interface, forming communicating holes and leading to severe defects that reduce a fuel sealing capability in a joined part of the nozzle tube and the stationary core.SOLUTION: An annular non-mated portion is formed in a portion of a mated part of a stationary core which is pressure-fit into an inside peripheral part of a nozzle tube, thereby eliminating welding defects due to vaporization of a lubricant due to joining of the nozzle tube and the stationary core by welding in this non-mated portion.

Description

  The present invention relates to an electromagnetic fuel injection valve used for an internal combustion engine mounted on an automobile, and more particularly to an electromagnetic fuel injection valve in which a nozzle cylinder for guiding a movable core is fixed to a fixed core.

  In general, an electromagnetic fuel injection valve that injects fuel into air supplied to an internal combustion engine generates a magnetic flux in a magnetic path including a movable core and a fixed core by flowing an electric current through the coil, and the movable core end surface and the fixed core end surface By generating a magnetic attractive force in the gap (magnetic attractive gap) between the two and the movable core is attracted to the fixed core side, the valve connected to the movable core is opened and closed to inject fuel. .

  Specifically, a fixed core can be fixed inside a nozzle cylinder made of a metal cylinder member having magnetic permeability, and a movable core can be arranged in the nozzle cylinder to be attracted to or pulled away from the fixed core. In this configuration, an electromagnetic coil and a housing that covers the electromagnetic coil are mounted outside the nozzle cylinder so as to supply magnetic flux to the movable core and the fixed core. Such an electromagnetic fuel injection valve is already well known.

  And as for the fixing structure of the nozzle cylinder and the fixed core disposed inside thereof, a method of fixing by press-fitting and a method of joining the press-fitting portion by welding are adopted. Such a fixing structure of the nozzle cylinder and the fixed core is described in Japanese Patent Application Laid-Open No. 2011-52557 (Patent Document 1) already filed by the present applicant.

JP 2011-52557 A

  In the technology described in Patent Document 1 described above, the nozzle cylinder and the inner fixed core are fitted together, that is, they are welded together in a press-fitted state. In order to reduce the press-fitting load during the press-fitting work, a lubricant or lubricating oil is applied to the press-fitting boundary surface between the nozzle cylinder and the fixed core, and a laser beam welder is used while leaving the lubricant and lubricating oil. Welded together.

  However, the heat generated by welding at this time may cause welding defects due to evaporation of the lubricant confined in the boundary surface together with the molten metal. This welding defect occurs when the metal solidifies while the lubricant evaporates in the process of the solidification of the molten metal at the time of welding, and the lubricant moves from the press-fit interface to the molten metal surface of the weld. It is that the communication hole along the path | route which vaporized opened.

  This welding defect is called a blow hole or pit, and it becomes a serious defect that reduces the fuel seal performance at the joint between the nozzle cylinder of the electromagnetic fuel injection valve and the fixed core, and it is important to suppress this welding defect Met.

  An object of the present invention is to provide an electromagnetic fuel injection valve that suppresses the occurrence of welding defects and improves the fuel seal performance of the fixed portion of the nozzle cylinder and the fixed core.

  A feature of the present invention is a nozzle cylinder having a nozzle hole for injecting fuel at the tip, a fixed core having an outer peripheral part that is press-fitted into the inner peripheral part of the nozzle cylinder and forms a fitting part with the inner peripheral part, A movable core disposed in the nozzle cylinder, facing the fixed core and reciprocating in the nozzle cylinder, a valve body driven by the movable core to open and close the nozzle hole, and disposed on the outer periphery of the nozzle cylinder, In an electromagnetic fuel injection valve provided with an electromagnetic coil for electromagnetically driving, an annular non-fitting part is formed in a part of the fitting part, and the nozzle cylinder and the fixed core are formed by this non-fitting part. It is in place where it is welded.

  Since the presence of the lubricant in the annular gap can be suppressed or eliminated in some cases, the molten metal containing the lubricant melt-bonded in the annular gap is reduced. Therefore, in the process where the molten metal solidifies during welding, the metal does not solidify during the evaporation of the lubricant, and steam flows from the press-fit boundary surface toward the molten metal surface to form a communication hole. Therefore, the occurrence of welding defects can be suppressed.

It is a longitudinal section showing the whole electromagnetic fuel injection valve composition to which the present invention is applied. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the conventional electromagnetic fuel injection valve. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes one Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention. It is an expanded sectional view which shows the detail of the fixing | fixed part between the nozzle cylinder and fixed core of the electromagnetic fuel injection valve which becomes the other Example of this invention.

  Next, an embodiment according to the present invention will be described, but before that, a specific structure of the fuel injection valve and problems of the prior art will be described.

  FIG. 1 is a longitudinal sectional view showing the overall configuration of an electromagnetic fuel injection valve to which the present invention is applied. The electromagnetic fuel injection valve of this embodiment is configured to supply fuel such as gasoline into a cylinder (combustion chamber) of an internal combustion engine. This is an electromagnetic fuel injection valve for injection.

  The electromagnetic fuel injection valve main body 1 has a cylindrical nozzle cylinder 2 formed of a metal having magnetic permeability, a hollow fixed member that is positioned on the inner peripheral side of the nozzle cylinder 2 and is fixedly coupled to the nozzle cylinder 2. Core 3, movable core 4 disposed on the opposing surface of fixed core 3 and accommodated movably in nozzle cylinder 2, electromagnetic coil 5 covered with synthetic resin fixedly disposed on the outer periphery of nozzle cylinder 2, electromagnetic coil 5 includes a housing 6 that also serves as a yoke and the like, and these components serve as magnetic circuit components.

  A valve body 41 is accommodated in an inner diameter portion formed inside the movable core 4, and the movement of the movable core 4 in the axial direction and the movement of the valve body 41 are synchronized by the action of the spring 8. An orifice cup 7 is housed and fixed on the tip end side of the communication hole 21 formed in the nozzle cylinder 2, and injection holes 71 and 72 are bored in the orifice cup 7. Although the number of nozzle holes 71 and 72 is two in this embodiment, two or more nozzle holes may be provided.

  The fuel is supplied from the upstream side of the communication hole 31 provided in the fixed core 3 and flows into the orifice cup 7 through the fixed core 3 and the communication hole 21 of the nozzle cylinder 2. A filter 10 is installed in the upstream portion of the communication hole 31 of the fixed core 3 to prevent entry of foreign matters contained in the flowing fuel.

  The valve body 41 is provided with an elastic force by the spring 8 accommodated in the communication hole 31 of the fixed core 3, and the valve body 41 contacts the orifice cup 7 by this elastic force. This elastic force generates a force by compressing the spring 8 and transmits the valve closing force to the valve body 41.

  This elastic force needs to be adjusted and set appropriately, and is adjusted by the insertion fixing position of the adjuster 9 installed in the communication hole 31 of the fixed core 3 and the spring 8 disposed in the communication hole 31. . The adjuster 9 is located on the opposite side of the valve body 41 via the spring 8 and is fixed to the communication hole 31 of the fixed core 3 by a method such as press fitting.

  The fixed core 4, the housing 6, the lead terminal 13, and the like are integrated by an injection valve base 14 made of synthetic resin.

  And between the upper part of the nozzle cylinder 2 and the fixed core 3, it is set as the fitting part 200 by press injection, In this fitting part 200, the nozzle cylinder 2 and the fixed core 3 are being fixed by the welding coupling | bond part. The fitting portion 200 has a role of fixing the nozzle cylinder 2 and the fixed core 3 and a role of preventing fuel from flowing out from the communication holes 21 and 31 to the electromagnetic coil 5 side. Laser beam beam welding is used for welding the weld joint 0.

  When the electromagnetic coil 6 is not energized, the valve body 41 and the orifice cup 7 constitute a metal seal so that fuel is not ejected from the nozzle holes 71 and 72.

  When an appropriate current is applied to the electromagnetic coil 5 via the lead terminal 13, a magnetic field is generated around the electromagnetic coil 5, and the above-described magnetic circuit, here, the fixed core 3, the movable core 4, the housing 6, and the nozzle. Magnetic flux flows through the cylinder 2, and an electromagnetic attractive force is generated in the movable core 4 so as to narrow the gap formed at the boundary between the fixed core 3 and the movable core 4.

  Since the valve element 41 is restricted in the radial movement by the two guide members 11 and 12 installed between the movable core 4 and the orifice cup 7 inside the communication hole 21 of the nozzle cylinder 2, the movable core As the valve 4 moves in the axial direction, the valve element 41 starts to move away from the orifice cup 7. As a result, the fuel blocked by the orifice cup 7 and the valve body 41 flows into the injection holes 71 and 72, is injected outside, and is supplied into the combustion chamber of the internal combustion engine.

  After that, when the current applied to the electromagnetic coil 6 is interrupted, the magnetic field of the electromagnetic coil 5 disappears and the magnetic flux decreases from the magnetic circuit. As a result, the valve closing force applied to the valve element 41 by the spring 8 exceeds the magnetic attractive force generated in the movable core 4, so that the valve element 41 moves toward the orifice cup 7 and finally comes into contact with the orifice cup 7. By configuring the metal seal, the fuel supply into the combustion chamber is completed. This series of processes is called an operation of the electromagnetic fuel injection valve, that is, a stroke.

  As an example of the control of the electromagnetic fuel injection valve of the present embodiment, the length of the suction time of the movable core 4 is changed by controlling the length of the application time of the current applied to the electromagnetic coil 5, and as a result, the valve The length of time that the body 41 is away from the orifice cup 7 can be controlled. As a result, the fuel injection amount per stroke of the valve body 41 can be controlled.

  As described above, the fuel flows in the respective communication holes 21 and 31 of the fixed core 3 and the nozzle cylinder 2, but it is necessary to always maintain the fuel seal at the joint portion from the viewpoint of safety. A number of sealing methods are conceivable, but a method of welding the fixed core 3 and the fitting portion 200 of the nozzle cylinder 2 is generally used as a method for reliably and inexpensively manufacturing.

  FIG. 2 shows a conventional detailed structure in which the fitting portion 200 between the fixed core 3 and the nozzle cylinder 2 is welded. The nozzle cylinder 2 and the fixed core 3 are fitted and held by press-fitting a nozzle cylinder inner peripheral portion 22 and a fixed core outer peripheral portion 32. In this figure, illustration of the electromagnetic coil 5 is omitted.

  That is, the fixed core outer peripheral portion 32 is set slightly larger than the nozzle cylinder inner peripheral portion 22. For this reason, the fitting part 200 of both has a structure which can ensure adhesiveness. Further, the welded joint 300 is formed by welding the fitting part 200 from the outer peripheral part 23 side of the nozzle cylinder 21. The welded joints 300 are distributed in the circumferential direction of the nozzle cylinder 2 and the fixed core 3 to ensure the fuel seal of the fitting part 200.

  The reason why the nozzle cylinder 2 and the fixed core 3 are press-fitted is that the valve body 41 needs to be operated so that the inclination is reduced as much as possible due to the nature of the electromagnetic fuel injection valve. This is a configuration necessary for maintaining accuracy. Furthermore, since the inclination of the nozzle cylinder 2 and the fixed core 3 can be reduced by setting the length of the fitting portion 200 to be large, the assembly accuracy can be maintained with high accuracy.

  If the length of the fitting part 200 is set to be large, the assembly load at the time of press-fitting is expected to increase. Therefore, a lubricant or lubricating oil (hereinafter collectively referred to as a lubricant) is applied to the fitting part 200. The process of performing is performed.

  However, when the lubricant is applied, the lubricant may remain in the fitting portion 200, and there is a possibility that a welding defect is caused in the weld joint portion 300. If a weld defect occurs in the weld joint 300, the desired fuel seal performance may not be ensured and safety may not be satisfied. In addition, there is a risk that the manufacturing cost is increased to ensure the sealing performance in the manufacturing process.

  This welding defect is called a blow hole or pit, and is a phenomenon in which a hole communicating from the fitting portion 200 toward the surface of the weld joint portion 300 is opened. The cause of the formation of blowholes and pits is that in the process where the molten metal at the time of welding is solidified again, the lubricant evaporates together with the molten metal, so that the steam pressure increases and escapes to the outer periphery of the welded joint 300 in the molten state. This is because the molten metal is cooled and solidified. As a result, a hole communicating from the fitting portion 200 toward the surface of the welded joint portion 300 is opened along the path where the lubricant is evaporated.

  As described above, the welding defect becomes a serious defect that reduces the fuel seal performance in the joint portion between the nozzle cylinder and the fixed core of the electromagnetic fuel injection valve, and it has been an important issue to suppress the welding defect.

  The present invention proposes a novel structure of the fitting portion 200 between the fixed core 3 and the nozzle tube 2 that can suppress the occurrence of this welding defect and improve the fuel seal performance of the fixed portion between the nozzle tube and the fixed core. To do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but a plurality of embodiments are proposed in the present invention. Accordingly, components having the same reference numbers represent the same components or components having similar functions.

  FIG. 3 shows a first embodiment of the present invention. In a part of the range where the inner peripheral portion 22 provided on the upper tip side of the nozzle tube 2 and the outer peripheral portion 32 of the fixed core 3 overlap each other, the nozzle tube 2 A fitting part 200 is formed in which the inner peripheral part 22 and the outer peripheral part 32 of the fixed core 3 are flat. The range in which the inner peripheral portion 22 provided on the upper tip side of the nozzle cylinder 2 and the outer peripheral portion 32 of the fixed core 3 overlap is about 2 mm to 3 mm, and the fitting portion 200 is about 1 mm.

  In the embodiment described below, the overlapping range of the inner peripheral portion 22 and the outer peripheral portion 32 is about 2 mm to 3 mm, and the fitting portion 200 is about 1 mm.

  Below the outer peripheral portion 32 constituting the remaining range of the fitting portion 200 of the fixed core 3 (the range other than the fitting portion 200 in the range where the inner peripheral portion 22 and the outer peripheral portion 32 of the fixed core 3 overlap). A diameter-reduced outer peripheral portion 33 having a diameter smaller than that of the outer peripheral portion 32 (the outer diameter is shortened) is formed.

  As a result, a minute annular gap 201 is formed in the inner peripheral portion 22 of the nozzle cylinder 2 and the reduced diameter outer peripheral portion 33 of the fixed core 3. The length in the radial direction of the annular gap 201 is determined to be about a few tens of microns. This annular gap 201 is paraphrased as a non-fitting part with respect to the fitting part 200, and is the same in the following embodiments, and the radial length of the gap 201 is also about 10 and several microns.

  The annular gap 201 is opened through an open portion 202 on the lower side of the fixed core 3, and the fixed core 3 is in a section where the annular gap 201 exists between the open portion 202 and the fitting portion 200. And the welded joint 300 of the nozzle cylinder 2 is located.

  Since the annular gap 201 is separated from the fitting portion 200, the degree of the lubricant entering the annular gap 201 is reduced even when the lubricant is applied to the fitting portion 200 during press-fit assembly. ing. That is, the amount of lubricant in the annular gap 201 (non-fitting part) is small with respect to the fitting part 200 or is not present in some cases.

  Furthermore, since the length of the fitting part 200 is shortened and the press-fitting load is reduced, and it is not required to apply the lubricant so much, the amount of the lubricant can be reduced.

  Therefore, the annular gap 201 exists even if the welding connection part 300 is formed by laser beam welding after applying the lubricant to the fitting part 200 between the fixed core 3 and the nozzle cylinder 2 and performing press-fit assembly. Since there is little lubricant in the section, the vapor pressure of the evaporating lubricant does not increase so much, and the occurrence of welding defects is suppressed.

  In addition, since the lower part of the annular gap 201 is opened by the opening part 202, the vapor of the evaporated lubricant is allowed to escape through the opening part 202, and the steam pressure is further reduced, resulting in welding defects. Can be suppressed.

  Further, if the top and bottom of the state shown in FIG. 3 is reversed so that the fitting portion 200 is located on the ground side, the lubricant does not flow into the annular gap 201, and the occurrence of welding defects can be further suppressed. It becomes.

  Next, a second embodiment of the present invention will be described. FIG. 4 shows a configuration in which the positions of the fitting portion 200 and the annular gap 201 are reversed in the axial direction from the embodiment shown in FIG.

  In FIG. 4, the nozzle cylinder 2 inner peripheral portion 22 and the fixed core 3 are partially overlapped with the inner peripheral portion 22 provided inside the nozzle cylinder 2 and the outer peripheral portion 32 on the lower tip side of the fixed core 3. A fitting part 200 having a flat outer peripheral part 32 is formed. On the upper side of the outer peripheral portion 32 constituting the remaining range of the fitting portion 200 of the fixed core 3 (the range other than the fitting portion 200 in the range where the inner peripheral portion 22 and the outer peripheral portion 32 of the fixed core 3 overlap) A diameter-reduced outer peripheral portion 34 having a diameter smaller than that of the outer peripheral portion 32 (the outer diameter is shortened) is formed, so that the inner peripheral portion 22 of the nozzle cylinder 2 and the reduced-diameter outer peripheral portion 34 of the fixed core 3 A minute annular gap 201 is formed.

  This annular gap 201 is a butting opening 203 of the butting portion on the upper end side of the fixed core 3 and the nozzle cylinder 2 (the opening is not shown in the drawing, but a gap that allows steam to escape is actually formed). The welded joint portion 300 between the fixed core 3 and the nozzle cylinder 2 is located in a section where the annular gap 201 exists between the butted opening portion 203 and the fitting portion 200.

  Since the annular gap 201 is separated from the fitting portion 200, the degree of the lubricant entering the annular gap 201 is reduced even when the lubricant is applied to the fitting portion 200 during press-fit assembly. ing. That is, the amount of lubricant in the annular gap 201 (non-fitting part) is small with respect to the fitting part 200 or is not present in some cases.

  Therefore, the annular gap 201 exists even if the welding connection part 300 is formed by laser beam welding after applying the lubricant to the fitting part 200 between the fixed core 3 and the nozzle cylinder 2 and performing press-fit assembly. Since there is little lubricant in the section, the vapor pressure of the evaporating lubricant does not increase so much, and the occurrence of welding defects is suppressed.

  Further, since the annular gap 201 is opened by the butt opening 203, the vapor of the evaporated lubricant is allowed to escape through the butt opening 203, and the steam pressure is further reduced to generate welding defects. Can be suppressed.

  Further, even if the amount of lubricant vapor passing through the butt opening 203 is small, the pressure of the generated steam is relieved by the presence of the volume of the annular gap 201 due to the presence of the annular gap 201. It is suppressed that a vapor | steam goes to the coupling | bond part 300. FIG. Therefore, generation | occurrence | production of a welding defect can be suppressed.

  As is the case with the first embodiment, it is desirable to apply the lubricant only in the vicinity of the fitting portion 200 when the nozzle cylinder 2 and the fixed core 3 are press-fitted and assembled.

  Further, in this embodiment, when the lubricant is applied to the inner peripheral portion 22 of the nozzle cylinder 2, the lubricant can be further prevented from entering the annular gap 201. This is because the lubricant is scraped off at the fitting portion 200 when press-fitting. This is because the lubricant may be transferred to the annular gap 201 by the inner peripheral portion 22 of the nozzle cylinder 2 when applied to the outer peripheral portion 32 of the fixed core 3. However, this can be prevented by improving the press-fitting method.

  In short, the amount of lubricant in the annular gap 201 (non-fitting part) may be small with respect to the fitting part 200.

  Next, a third embodiment of the present invention will be described. FIG. 5 shows a fitting portion 200 in which the inner peripheral portion 22 of the nozzle cylinder 2 and the outer peripheral portion 32 of the fixed core 3 are flattened in two places at the top and bottom. It is positioned so that an annular gap 201 exists between them.

  In FIG. 5, a first fitting portion 200 </ b> A is configured on an inner peripheral portion 22 provided inside the nozzle cylinder 2 and an outer peripheral portion 32 on the lower end side of the fixed core 3. Further, a second fitting portion 200 </ b> B is configured on the inner peripheral portion 22 provided on the inner side of the nozzle cylinder 2 and the outer peripheral portion 32 on the opposite side of the lower end side of the fixed core 3.

  Between the first fitting portion 200A and the second fitting portion 200B of the fixed core 3, a reduced diameter outer peripheral portion 34 is formed from the outer peripheral portion 32 (the outer diameter is shortened). A minute annular gap 201 is formed in the inner peripheral portion 22 of the nozzle cylinder 2 and the reduced diameter outer peripheral portion 34 of the fixed core 3. The welded joint 300 between the fixed core 3 and the nozzle cylinder 2 is located in the presence section of the annular gap 201, preferably in the vicinity of the center.

  Since the annular gap 201 is separated from the first fitting portion 200A and the second fitting portion 200B, even if the lubricant is applied to the fitting portion 200 during press-fit assembly, the lubricant remains in the annular gap 201. It is set as the structure by which the degree which penetrate | invades into becomes small. That is, the amount of lubricant in the annular gap 201 (non-fitting part) is small with respect to the fitting part 200 or is not present in some cases.

  Accordingly, after the lubricant is applied to the fixed core 3 and the first fitting part 200A and the second fitting part 200B of the nozzle cylinder 2 and press-fit assembly is performed, the weld connecting part is connected to the annular gap 201 by laser beam welding. Even if 300 is formed, since there is little lubricant in the section where the annular gap 201 exists, the vapor pressure of the evaporated lubricant does not increase so much, and the occurrence of welding defects is suppressed.

  In addition, since the increase in the pressure of the steam generated by the presence of the volume of the annular gap 201 is mitigated, the steam is suppressed from moving toward the welded joint 300 in the molten state. Therefore, generation | occurrence | production of a welding defect can be suppressed.

  In addition, it is desirable to apply the lubricant during the press-fitting assembly of the nozzle cylinder 2 and the fixed core 3 only in the vicinity of the fitting portion 200, but further, it is lower than the portion where the annular gap 201 is formed. It is good to apply to the inner peripheral portion 22 of the nozzle cylinder 2 constituting the first fitting portion 200A.

  This is because the lubricant is scraped off at the fitting portion 200A when press-fitting. This is because the lubricant may be transferred to the annular gap 201 by the inner peripheral portion 22 of the nozzle cylinder 2 when applied to the outer peripheral portion 32 of the fixed core 3. However, this can be prevented by improving the press-fitting method.

  The point is that the amount of lubricant in the annular gap 201 (non-fitting part) with respect to the fitting part 200 should be small.

  Furthermore, in the present embodiment, the fitting portion is divided into two portions of the first fitting portion 200A and the second fitting portion 200B, so that the length of the fitting portion 200 is increased. Has the same effect. In other words, in the electromagnetic fuel injection valve, it is necessary to operate the valve body 41 so that the inclination is as small as possible. By providing the two fitting portions 200A and 200B, the coaxiality between the nozzle cylinder 2 and the fixed core 3 is increased. The accuracy can be maintained.

  In addition, since the total length of the actual fitting portion 200 can be shortened as compared with the conventional electromagnetic fuel injection valve fitting portion (for example, FIG. 2), the press-fit load during assembly is reduced. Is possible. Therefore, the application of the lubricant during the assembly of the nozzle cylinder 2 and the fixed core 3 can be reduced as much as possible, and the evaporation of the lubricant can be reduced correspondingly, and the occurrence of welding defects can be suppressed.

  In particular, in this embodiment, since the press-fitting load at the time of assembly can be reduced, it is possible to omit the application of the lubricant when press-fitting the nozzle cylinder 2 and the fixed core 3 at the time of assembly. According to this, since there is no lubricant itself, no welding defect occurs.

  In the embodiment of FIG. 5, the annular gap 201 is formed in the reduced diameter outer peripheral portion 34 of the fixed core 3, but the inner diameter of the nozzle cylinder 2 is increased by making the outer diameter of the fixed core 3 constant. An annular gap 201 may be formed. In this case, the first fitting portion 200A and the second fitting portion 200B are formed on both sides of the enlarged inner peripheral diameter portion.

Next, a fourth embodiment of the present invention will be described. In FIG. 6, the fitting portion 200 is formed in two upper and lower portions, the position of the annular gap 201 is determined between them, and one or more circles are formed on the fitting portion 200. An annular groove is formed.
In FIG. 6, a first fitting portion 200 </ b> A is configured on an inner peripheral portion 22 provided inside the nozzle cylinder 2 and an outer peripheral portion 32 on the lower tip side of the fixed core 3. Further, a second fitting portion 200 </ b> B is configured in an inner peripheral portion 22 provided on the inner side of the nozzle cylinder 2 and an outer peripheral portion 32 on the opposite side to the distal end side of the fixed core 3.

  The first fitting portion 200A and the second fitting portion 200B are formed with one or more annular grooves 204, here three.

  Between the first fitting portion 200A and the second fitting portion 200B of the fixed core 3, a reduced-diameter outer peripheral portion 34 that is reduced in diameter (the outer diameter is shortened) from the outer peripheral portion 32 is formed. As a result, a minute annular gap 201 is formed in the inner peripheral portion 22 of the nozzle cylinder 2 and the reduced diameter outer peripheral portion 34 of the fixed core 3. The welded joint 300 between the fixed core 3 and the nozzle cylinder 2 is located in the section where the annular gap 201 exists.

  Since the annular gap 201 is separated from the first fitting portion 200A and the second fitting portion 200B, even if the lubricant is applied to the fitting portion 200 during press-fit assembly, the lubricant remains in the annular gap 201. It is set as the structure by which the degree which penetrate | invades into becomes small. That is, the amount of lubricant in the annular gap 201 (non-fitting part) is small with respect to the fitting part 200 or is not present in some cases.

  Furthermore, since the fine multiple annular grooves 204 are provided on the surfaces of the first fitting portion 200A and the second fitting portion 200B, the lubricant is stored in the fine annular grooves 204 with surface tension. The lubricant can be prevented from entering the annular gap 201 when the nozzle cylinder 2 and the fixed core 3 are press-fitted.

Accordingly, after the lubricant is applied to the fixed core 3 and the first fitting part 200A and the second fitting part 200B of the nozzle cylinder 2 and press-fit assembly is performed, the weld connecting part is connected to the annular gap 201 by laser beam welding. Even if 300 is formed, since there is little lubricant in the section where the annular gap 201 exists, the vapor pressure of the evaporated lubricant does not increase so much, and the occurrence of welding defects is suppressed.
Further, as described above, due to the presence of the annular gap 201, the pressure of the generated steam is relieved by the presence of the volume of the annular gap 201, so that the steam is prevented from moving toward the welded joint 300 in the molten state. . Therefore, generation | occurrence | production of a welding defect can be suppressed.

  In addition, it is desirable to apply the lubricant during the press-fitting assembly of the nozzle cylinder 2 and the fixed core 3 only in the vicinity of the fitting portion 200.

  Further, in the present embodiment, by providing the annular groove 204, the total length of the fitting portions 200A and 200B can be shortened as compared with the embodiment shown in FIG. For this reason, the reduction effect of the press-fit load at the time of the assembly of the nozzle cylinder 2 and the fixed core 3 can be further expected.

In addition, according to the configuration in which the annular groove 204 is formed, the lubricant can be retained in the annular groove 204, so that it is possible to press-fit with a small amount of lubricant in the press-fitting process at the time of assembly. As a result, the degree of the lubricant entering the annular gap 201 is reduced, and the occurrence of welding defects can be suppressed.
Further, as described above, due to the presence of the annular gap 201, the pressure of the generated steam is relieved by the presence of the volume of the annular gap 201, so that the steam is prevented from moving toward the welded joint 300 in the molten state. . Therefore, generation | occurrence | production of a welding defect can be suppressed.

  In the case of the structure shown in FIG. 6, when a lubricant is applied to the fitting part 200 </ b> A and the fitting part, the first fitting part 200 </ b> A downstream from the annular gap 201 or the second upstream side from the annular gap 201. Although it may apply | coat to one of the fitting parts 200B, if it apply | coats to both fitting parts 200A and 200B, the effect of a press-fit load reduction can be anticipated further. Thereby, the coaxiality of the nozzle cylinder 2 and the fixed core 3 can be maintained with high accuracy by providing the two fitting portions 200A and 200B.

  The first fitting portion 200A is coated with a lubricant on the inner peripheral portion 22 of the nozzle cylinder 2, and the second fitting portion 200B is coated with a lubricant on the outer peripheral portion 32 of the fixed core 3. Yes.

  Here, in this embodiment, the annular groove 204 is provided on the outer peripheral portion side of the fixed core 3, but may be provided on the inner peripheral portion 22 side of the nozzle cylinder 2. In this case, the first fitting portion 200A is formed over the second fitting portion 200B.

Next, a fifth embodiment of the present invention will be described. In FIG. 7, the fitting part 200 is formed in two upper and lower parts, the position of the annular gap 201 is determined between them, and either one of the fitting parts 200 is formed. A plurality of annular grooves are formed. In this embodiment, a structure in which the annular gap 201 is formed in the fitting portion 200B on the upper side of the annular gap 201 is shown.

  In FIG. 7, a first fitting portion 200 </ b> A is configured on an inner peripheral portion 22 provided inside the nozzle cylinder 2 and an outer peripheral portion 32 on the lower tip side of the fixed core 3. Further, a second fitting portion 200 </ b> B is configured in an inner peripheral portion 22 provided on the inner side of the nozzle cylinder 2 and an outer peripheral portion 32 on the opposite side to the distal end side of the fixed core 3. A plurality (three in this case) of annular grooves 204 are formed in the second fitting portion 200B.

  Between the first fitting portion 200A and the second fitting portion 200B of the fixed core 3, a reduced-diameter outer peripheral portion 34 that is reduced in diameter (the outer diameter is shortened) from the outer peripheral portion 32 is formed. As a result, a minute annular gap 201 is formed in the inner peripheral portion 22 of the nozzle cylinder 2 and the reduced diameter outer peripheral portion 34 of the fixed core 3. The welded joint 300 between the fixed core 3 and the nozzle cylinder 2 is located in the section where the annular gap 201 exists.

  Since the annular gap 201 is separated from the first fitting portion 200A and the second fitting portion 200B, even if the lubricant is applied to the fitting portion 200 during press-fit assembly, the lubricant remains in the annular gap 201. It is set as the structure which decreases the degree which penetrate | invades into. That is, the amount of lubricant in the annular gap 201 (non-fitting part) is small with respect to the fitting part 200 or is not present in some cases.

  In the case where the two fitting portions 200A and 200B are provided, the lubricant is preferably applied above the annular gap 201. Therefore, in the present embodiment, the second fitting portion 200B above the annular gap 201 is configured. A plurality of annular grooves 204 are provided in the outer peripheral portion 32 of the fixed core 3 to be configured.

  On the other hand, when a plurality of annular grooves 204 are provided in the inner peripheral portion 22 of the nozzle cylinder 2, the annular grooves 204 are positioned in the lower first fitting portion 200 </ b> A across the annular gap 202. Is desirable.

  In the embodiment of FIGS. 5, 6 and 7 described above, the fitting portion is divided into the first fitting portion 200A and the second fitting portion 200B in the axial direction. The inner diameter of the inner peripheral portion 22 of the nozzle cylinder 2 forming the fitting portion and the outer diameter of the fixed core 3 are set to be substantially the same diameter.

  However, it is not necessary to set with the same diameter, and an embodiment as described below may be adopted. Below, the detail is demonstrated about a fitting part.

Next, a fifth embodiment of the present invention will be described. In FIG. 8, the inner diameter of the inner peripheral portion 22 of the nozzle cylinder 2 constituting one of the fitting portions 200 and the outer diameter of the outer peripheral portion 32 of the fixed core 3 are changed. Is.

  In FIG. 8, the inner diameter of the inner peripheral portion 22B of the nozzle cylinder 2 of the second fitting portion is larger than the inner diameter of the inner peripheral portion 22A of the nozzle cylinder 2 of the first fitting portion 200A. In accordance with this, the outer diameter of the outer peripheral portion 32B of the fixed core 3 of the second fitting portion is larger than the outer diameter of the outer peripheral portion 32A of the fixed core 3 of the first fitting portion 200A.

  As shown in FIG. 8, the second fitting part 200 </ b> B is located above the annular gap 201 and the welded joint part 300, and the first fitting part has the same configuration as that of the above-described embodiment. Yes.

  In FIG. 8, the inner peripheral portion 22A of the nozzle cylinder 2 that forms the first fitting portion 200A and the outer peripheral portion 32A of the fixed core 3 are in a press-fitting and fitting relationship, and the nozzle that similarly forms the second fitting portion 200B. The inner peripheral portion 22B of the cylinder 2 and the outer peripheral portion 32B of the fixed core 3 are also in a press-fitting and fitting relationship.

  In this state, an annular gap 201 is formed between the nozzle tube 2 and the fixed core 3 due to the dimensional relationship between the inner peripheral portions 22 </ b> A and 22 </ b> B of the slip tube 2 and the outer peripheral portions 32 </ b> A and 32 </ b> B of the fixed core 3. As a result, it is possible to obtain the same effects as those of the embodiments of FIGS.

Next, a sixth embodiment of the present invention will be described with reference to FIG. 9, which shows a modification of the fifth embodiment.

  In FIG. 9, the inner diameter of the inner peripheral portion 22B of the nozzle cylinder 2 of the second fitting portion is larger than the inner diameter of the inner peripheral portion 22A of the nozzle cylinder 2 of the first fitting portion 200A. In accordance with this, the outer diameter of the outer peripheral portion 32B of the fixed core 3 of the second fitting portion is larger than the outer diameter of the outer peripheral portion 32A of the fixed core 3 of the first fitting portion 200A.

  Furthermore, the outer peripheral portion of the fixed core 3 is reduced in diameter from the outer peripheral portion 32A of the fixed core 3 facing the inner diameter portion of the inner peripheral portion 22A of the nozzle tube 2 of the first fitting portion 200A. Is formed. As shown in FIG. 9, the second fitting part 200 </ b> B is located above the annular gap 201 and the welded joint part 300, and the first fitting part has the same configuration as that of the above-described embodiment. Yes.

  In FIG. 9, the inner peripheral portion 22A of the nozzle cylinder 2 forming the first fitting portion 200A and the outer peripheral portion 32A of the fixed core 3 are in a press-fitting and fitting relationship, and similarly, the second fitting portion 200B is formed. The inner peripheral portion 22B of the nozzle cylinder 2 and the outer peripheral portion 32B of the fixed core 3 are also press-fitted and fitted.

  In this state, an annular gap 201 is formed between the nozzle tube 2 and the fixed core 3 due to the dimensional relationship between the inner peripheral portions 22 </ b> A and 22 </ b> B of the slip tube 2 and the outer peripheral portions 32 </ b> A and 32 </ b> B of the fixed core 3. As a result, it is possible to obtain the same effects as those of the embodiments of FIGS.

  8 and 9 can obtain the same effects as those of the embodiments of FIGS. 5, 6 and 7 by installing the annular groove 204 in the fitting portion 200A.

  Furthermore, according to the embodiment of FIGS. 6, 7, 8, and 9 described in the present invention, the annular groove 204 can be expected to further exhibit the effects described below.

  When the annular groove 204 is installed in the nozzle cylinder 2, the cross-sectional area in the radial direction of the nozzle cylinder 2 is reduced, and the magnetic resistance can be increased. By increasing the magnetic resistance of the nozzle cylinder 2 in the magnetic circuit of the electromagnetic fuel injection valve, the magnetic flux can be concentrated on the fixed core 3 and the magnetic circuit efficiency is improved, so that the magnetic attractive force can be improved.

  Further, when the annular groove 204 is installed on the fixed core 3 side, an eddy current is generated on the surface of the fixed core 3, and the magnetic circuit demagnetization time is delayed due to the generation of the eddy current, and the valve closing response of the electromagnetic fuel injection valve It is known that the sex decreases. By setting the annular groove 204 on the outer periphery of the fixed core 3, an effect of reducing eddy current generated on the surface of the fixed core can be expected. Therefore, an improvement in valve closing response performance of the electromagnetic fuel injection valve can be expected.

  As described above, according to the embodiment of the present invention, one or more remarkable effects described below can be obtained. Needless to say, there are additional effects other than this.

  (1) Since the lubricant can be isolated in the annular gap, there is no molten metal containing the lubricant melt-bonded in the annular gap. Therefore, in the process where the molten metal solidifies during welding, the metal does not solidify during the evaporation of the lubricant, and steam flows from the press-fit boundary surface toward the molten metal surface to form a communication hole. Therefore, the occurrence of welding defects can be suppressed.

  (2) By providing a fine annular groove on the surface of the fitting portion, the lubricant is stored in the annular groove with surface tension, so that the lubricant can be prevented from entering the annular gap during press-fitting. Generation of welding defects can be further suppressed.

  (3) By providing a fine annular groove, the overall length of the fitting part can be reduced, so that an excessive press-fitting load is not applied when assembling the nozzle cylinder and the fixed core, ensuring the accuracy of the parts. Is possible.

  (4) If the annular groove is provided in the nozzle cylinder, the magnetic resistance constituting the magnetic circuit of the electromagnetic fuel injection valve can be increased, and the magnetic circuit efficiency of the electromagnetic fuel injection valve can be increased. That is, the magnetic flux can be actively collected to the fixed core side.

  (5) It is known that in the magnetic circuit, eddy current is generated on the surface of the fixed core, and the magnetic circuit demagnetization time is delayed due to the generation of eddy current, and the valve closing response of the electromagnetic fuel injection valve is lowered. By providing an annular groove on the outer periphery of the fixed core, an effect of reducing eddy currents generated on the surface of the fixed core can be expected. Therefore, an improvement in valve closing response performance of the electromagnetic fuel injection valve can be expected.

  (6) The entire press-fitting length can be shortened by dividing the fitting portion into two locations, and the length of the fitting portion in the axial direction is increased, so that the fall of the fitting portion between the fixed core and the nozzle cylinder is improved. Expected effects.

  DESCRIPTION OF SYMBOLS 1 ... Injection valve main body, 2 ... Nozzle cylinder, 22, 22A, 22B ... Inner peripheral part, 3 ... Fixed core, 32, 32A, 32B3 ... Outer peripheral part, 4 ... Movable core, 41 ... Valve body, 5 ... Housing, 6 DESCRIPTION OF SYMBOLS ... Electromagnetic coil, 7 ... Orifice cup, 71, 72 ... Injection hole, 8 ... Spring, 9 ... Adjuster, 10 ... Filter, 11, 12 ... Guide member, 13 ... Lead terminal, 14 ... Injection valve base, 200 ... Fitting Part, 200A ... first fitting part, 200B ... second fitting part, 201 ... annular gap, 204 ... annular groove, 300 ... weld joint part.

Claims (10)

A nozzle cylinder having a nozzle hole for injecting fuel at the tip, a fixed core having an outer peripheral part that is press-fitted into the inner peripheral part of the nozzle cylinder and forms a fitting part, and the nozzle cylinder A movable core disposed opposite to the fixed core and capable of reciprocating in the nozzle cylinder; a valve body driven by the movable core to open and close the nozzle hole; and disposed on an outer periphery of the nozzle cylinder, the movable In an electromagnetic fuel injection valve provided with an electromagnetic coil that electromagnetically drives a core,
An electromagnetic fuel injection valve characterized in that an annular non-fitting part is formed in a part of the fitting part, and the nozzle cylinder and the fixed core are welded to each other at the non-fitting part. In the electromagnetic fuel injection valve according to claim 1,
The fitting portions are provided at two locations on one side and the other side in a range where the inner peripheral portion of the nozzle cylinder and the outer peripheral portion of the fixed core overlap, and a non-fitting portion is provided between the two fitting portions. An electromagnetic fuel injection valve formed and formed by welding the nozzle cylinder and the fixed core in this range. In the electromagnetic fuel injection valve according to claim 1,
The fitting portion is provided on one side or the other side in a range where the inner peripheral portion of the nozzle tube and the outer peripheral portion of the fixed core overlap, and the remaining range becomes a non-fitting portion and the nozzle tube. An electromagnetic fuel injection valve, wherein the fixed core is welded. The electromagnetic fuel injection valve according to claim 2,
The non-fitting part is configured to have a large inner diameter of the inner peripheral part of the nozzle cylinder or a small outer diameter of the outer peripheral part of the fixed core and is formed as an annular gap. An electromagnetic fuel injection valve. The electromagnetic fuel injection valve according to claim 4,
2. The electromagnetic fuel injection valve according to claim 1, wherein the fitting portion is formed by fitting an inner peripheral portion of the nozzle cylinder and an outer peripheral portion of the fixed core on a flat surface and press-fitting each. The electromagnetic fuel injection valve according to claim 5,
The electromagnetic fuel injection valve, wherein the nozzle cylinder and the fixed core are welded to each other in the vicinity of the center of the range of the non-fitting part between the fitting parts. The electromagnetic fuel injection valve according to claim 5,
An electromagnetic fuel injection valve characterized in that a press-fit lubricant is not applied to each of the fitting portions and is fitted into a fitting state. In the electromagnetic fuel injection valve according to claim 1,
The fitting portion is provided at two locations on one side and the other side in a range where the inner peripheral portion of the nozzle cylinder and the outer peripheral portion of the fixed core overlap, and one of the fitting portions has an annular shape of one or more rings. An electromagnetic fuel injection valve characterized in that a groove is formed, a non-fitting part is formed between the two fitting parts, and the nozzle cylinder and the fixed core are welded together in this range. In the electromagnetic fuel injection valve according to claim 1,
The fitting portions are provided at two locations on one side and the other side in a range where the inner peripheral portion of the nozzle cylinder and the outer peripheral portion of the fixed core overlap, and at least one annular groove is formed in both the fitting portions. An electromagnetic fuel injection valve formed, wherein a non-fitting portion is formed between the two fitting portions, and the nozzle cylinder and the fixed core are welded and joined within this range. The electromagnetic fuel injection valve according to any one of claims 8 to 9,
The electromagnetic fuel injection valve, wherein the nozzle cylinder and the fixed core are welded to each other in the vicinity of the center of the range of the non-fitting part between the fitting parts.

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