JP4104508B2 - solenoid valve - Google Patents

Description

  The present invention relates to an electromagnetic valve such as an electromagnetic fuel injection valve for an internal combustion engine, and more particularly to an improvement of an electromagnetic valve including a hollow cylindrical member having a magnetic region and a nonmagnetic region adjacent in the axial direction.

Conventionally, the following are known as cylindrical members of such solenoid valves.
(1) As disclosed in Patent Document 1, a portion corresponding to the magnetic region is formed of a magnetic cylindrical body, and a portion corresponding to the non-magnetic region is formed of a magnetic cylindrical body, and these cylindrical bodies are integrated in the axial direction. Concatenated to
(2) As disclosed in Patent Document 2, an austenite-generating element is added to a part of a single cylindrical member having magnetism while irradiating a flame made of H ₂ -based fuel. A part of the member is alloyed to form a non-magnetic region.
JP 2003-106237 A JP-A-10-212588

  By the way, the cylindrical member (1) is configured by combining a plurality of members of a magnetic cylindrical body and a nonmagnetic cylindrical body. Therefore, the number of parts is large and the cost is inevitable. In the cylindrical member (2), the number of parts can be reduced, but in order to obtain a non-magnetic region, a special processing step of flame irradiation while adding an alloy-forming element must be performed. In other words, this hinders cost reduction.

  The present invention has been made in view of such circumstances, and while reducing the number of parts, the magnetic region and the non-magnetic region can be axially arranged without performing a special processing step such as addition of an alloying element. An object of the present invention is to provide a solenoid valve that can provide a hollow cylindrical member that is adjacent to the surface.

In order to achieve the above object, the present invention provides an electromagnetic valve including a hollow cylindrical member having a magnetic region and a nonmagnetic region adjacent in the axial direction, and the cylindrical member is integrally formed of a magnetic material, and The cylindrical member is formed with at least two annular penetration beads by laser irradiation spaced apart from each other in the axial direction of the cylindrical member. The first feature is that it is an area.

  The electromagnetic valve corresponds to an electromagnetic fuel injection valve V in an embodiment of the present invention described later.

  In addition to the first feature, the present invention has a second feature that the thickness of the cylindrical member in the nonmagnetic region is set to be smaller than the thickness in the magnetic region.

Furthermore, in addition to the first or second feature of the present invention, a third feature is that the depth of the penetration bead is set to approximately ½ of the thickness of the cylindrical member .

According to the first feature of the present invention, the non-magnetic region can be obtained by forming an annular penetration bead by simple laser irradiation on a single cylindrical member, so that no special non-cylindrical member is required. It is possible to reduce the number of parts and simplify the structure, and since it is not necessary to perform a special treatment such as adding an alloying element, it is easy to manufacture and can contribute to cost reduction as a whole. . In addition, a relatively wide nonmagnetic region can be formed in the cylindrical member by at least two penetration beads formed at intervals in the axial direction of the cylindrical member.

Further, according to the second feature of the present invention, the nonmagnetic characteristics of the nonmagnetic region can be further enhanced by the nonmagnetic effect of the penetration bead and the magnetic path constriction effect of the thin portion .

Furthermore, according to the third feature of the present invention, sufficient nonmagnetism can be imparted to the nonmagnetic region, and heat input by laser irradiation can be reduced to prevent distortion of the cylindrical member as much as possible.

  Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

  1 is a longitudinal sectional view of an electromagnetic fuel injection valve for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is an enlarged view of part 2 of FIG. 1, and FIG. 3 is a diagram showing a second embodiment of the present invention. 4 is a graph showing a test result of the relationship between the depth of the penetration bead and its nonmagnetic property, and FIG. 5 is a test result of the relationship between the width of the penetration bead and its nonmagnetic property. It is a graph to show.

  First, the description starts with the description of the first embodiment of the present invention shown in FIGS.

  A valve housing 2 of an electromagnetic fuel injection valve I for an internal combustion engine includes a cylindrical valve seat member 3 having a valve seat 8 at a front end, and a magnetic cylindrical member 4 coaxially coupled to a rear end portion of the valve seat member 3. It consists of. The magnetic cylindrical member 4 is based on Fe, for example, Tohoku special rope K-M57, C 0.18 wt%, Mo, Si, Al 12 wt% or less, Cu 2 wt%, Ni 4 wt%, Cr 9˜ A ferrite-based magnetic material containing 20 wt%, Ti 0.5 wt% or less, and other impurity elements, having a hardness adjusted to about Hmv 350 to 450.

  The valve seat member 3 has a connecting cylinder portion 3 a that protrudes to the rear end side with an annular shoulder 3 b from the outer peripheral surface thereof. Press fit. Then, the front end face of the magnetic cylindrical member 4 is brought into contact with the annular shoulder 3b, and an annular weld bead 35 is formed by laser welding over the entire circumference of the contact part. Thus, the valve seat member 3 and the magnetic cylindrical member 4 are coupled to each other coaxially and fluid-tightly.

  The valve seat member 3 includes a valve hole 7 that opens to a front end surface thereof, a conical valve seat 8 that is continuous with the inner end of the valve hole 7, and a cylindrical guide hole 9 that is continuous with a large diameter portion of the valve seat 8. And. A steel plate injector plate 10 having a plurality of fuel injection holes 11 communicating with the valve hole 7 is joined to the front end surface of the valve seat member 3 over the entire circumference by laser welding.

  A hollow cylindrical fixed core 5 is fitted to the inner peripheral surface of the magnetic cylindrical member 4 from the rear end side thereof, and all the contact portions between the rear end of the magnetic cylindrical member 4 and the annular shoulder 5c of the fixed core 5 are fitted. An annular weld bead 36 is formed around the circumference by laser welding. Thus, the magnetic cylindrical member 4 and the fixed core 5 are coupled to each other coaxially and in a liquid-tight manner.

  As described above, during welding between the valve seat member 3 and the magnetic cylindrical member 4 and between the magnetic cylindrical member 4 and the fixed core 5, a predetermined intermediate portion of the magnetic cylindrical member 4, specifically, the inner end of the fixed core 5 The annular penetration beads 37 and 37 by the laser irradiation of the same laser welding machine are simultaneously formed at a position corresponding to the above and a position spaced a predetermined distance from the position toward the valve seat member 3 side.

  Thus, each penetration bead 37 has a nonmagnetic effect that remarkably reduces the magnetic properties of the portion, and the portion sandwiched between the two penetration beads 37, 37 of the magnetic cylindrical member 4 thereby becomes a nonmagnetic region B. It is said. Accordingly, the single magnetic cylindrical member 4 is provided with the front magnetic region A, the nonmagnetic region B, and the rear magnetic region C adjacent to each other in the axial direction from the front end side (the valve seat member 3 side) (FIG. 2).

  A portion that does not fit with the fixed core 5 remains at the front end portion of the magnetic cylindrical member 4, and the valve assembly 15 is accommodated in the valve housing 2 extending from the portion to the valve seat member 3.

  The valve assembly 15 is connected to the valve body 17 and a valve body 18 including a hemispherical valve portion 16 that opens and closes the valve hole 7 in cooperation with the valve seat 8 and a valve flange portion 17 that supports the valve body 17. The movable core 12 is concentrically opposed to the fixed core 5. The valve rod portion 17 is formed to have a smaller diameter than the guide hole 9, and a pair of front and rear portions that protrude radially outward on the outer periphery thereof and are slidably supported on the inner peripheral surface of the guide hole 9. Journal portions 17a and 17a are integrally formed. In that case, both journal parts 17a and 17a are arrange | positioned, keeping the axial direction space | interval of both as much as possible.

  The movable core 12 is slidably disposed in the magnetic cylindrical member 4 from the front magnetic region A to the nonmagnetic region B.

  The valve assembly 15 includes a vertical hole 19 that ends from the rear end surface of the movable core 12 and before the valve portion 16, and a plurality of first horizontal holes 20 a that communicate with the outer peripheral surface of the movable core 12. A plurality of second horizontal holes 20b communicating the vertical hole 19 with the outer peripheral surface of the valve flange 17 between the journal portions 17a, 17a, and a plurality of third horizontal holes 20c communicating the vertical hole 19 with the outer peripheral surface of the valve portion 16. And are provided. At that time, an annular spring seat 24 facing the fixed core 5 is formed in the middle of the vertical hole 19.

  The fixed core 5 has a vertical hole 21 that communicates with the vertical hole 19 of the movable core 12, and a fuel inlet cylinder 26 that communicates internally with the vertical hole 21 is integrally provided at the rear end of the fixed core 5. The fuel inlet cylinder 26 includes a reduced diameter portion 26a connected to the rear end of the fixed core 5 and a subsequent enlarged diameter portion 26b. The pipe shape is inserted into the vertical hole 21 through the reduced diameter portion 26a or is lightly press-fitted. A valve spring 22 for biasing the movable core 12 toward the valve closing side of the valve body 18 is provided between the retainer 23 and the spring seat 24. At that time, the set load of the valve spring 22 is adjusted by the fitting depth of the retainer 23 into the vertical hole 21. After the adjustment, the outer peripheral wall of the reduced diameter portion 26a is partially caulked inward to retain the retainer 23. Is fixed to the reduced diameter portion 26a. A fuel filter 27 is attached to the enlarged diameter portion 26b.

  The fixed core 7 is made of a ferrite-based high hardness magnetic material.

  On the other hand, the movable core 12 is formed with a concave portion 13 (see FIG. 2) in the suction surface 12a facing the suction surface 5a of the fixed core 5, and the collar-like stopper element surrounding the valve spring 22 in the concave portion 13. 14 is fitted and fixed. For the fixing, press fitting, caulking, or welding is used. The stopper element 14 is made of a nonmagnetic material, for example, JIS SUS304 material.

  The stopper element 14 protrudes from the suction surface 12 a of the movable core 12 and is normally opposed to the suction surface 5 a of the fixed core 5 with a gap s corresponding to the valve opening stroke of the valve body 18. The suction surface 12a of the movable core 12 includes a reference suction surface F that faces the fixed core 5 with a predetermined air gap g when the stopper element 14 is in contact with the fixed core 5, and a fixed core 5 side from the reference suction surface F. And a projecting suction surface f projecting into the surface.

  The predetermined air gap g is set so that the residual magnetic flux between the cores 5 and 12 disappears rapidly when the coil 30 is demagnetized from the excited state. On the other hand, the protruding amount of the protruding suction surface f from the reference suction surface F is set in a range where the protruding suction surface f does not contact the suction surface of the fixed core 5 even when the stopper element 14 abuts on the fixed core 5. At this time, the area is set to be smaller than the area of the reference attraction surface F so that the protruding attraction surface f does not hinder the disappearance of the residual magnetism.

  A coil assembly 28 is fitted to the outer periphery of the valve housing 2 so as to correspond to the fixed core 5 and the movable core 12. The coil assembly 28 includes a bobbin 29 fitted to the outer peripheral surface of the magnetic cylindrical member 4 and a coil 30 wound around the bobbin 29, and a front end of a coil housing 31 surrounding the coil assembly 28 is formed. The magnetic cylindrical member 4 is welded to the outer peripheral surface of the front magnetic region A, and the rear end thereof is welded to the outer peripheral surface of the yoke 5b protruding in a flange shape from the outer periphery of the rear end portion of the fixed core 5. The coil housing 31 has a cylindrical shape, and a slit 31a extending in the axial direction is formed on one side.

  The coil housing 31, the coil assembly 28, the fixed core 5, and the front half of the fuel inlet cylinder 26 are embedded in a synthetic resin covering 32 by injection molding. At that time, the covering 32 is filled into the coil housing 31 through the slit 31a. In addition, a coupler 34 that accommodates the connection terminal 33 connected to the coil 30 is integrally connected to the intermediate portion of the covering body 32.

  Next, the operation of the first embodiment will be described.

  In a state where the coil 30 is demagnetized, the valve assembly 15 is pressed forward by the urging force of the valve spring 22, and the valve body 18 is seated on the valve seat 8. Therefore, the fuel pressure-fed from the fuel pump (not shown) into the fuel inlet cylinder 26 passes through the inside of the pipe retainer 23, the vertical hole 19 of the valve assembly 15, and the first to third horizontal holes 20a to 20c. And is used for lubrication around the journal portions 17a and 17a of the valve body 18.

  When the coil 30 is energized by energization, the magnetic flux generated thereby runs sequentially to the coil housing 31, the fixed core 5, the movable core 12, the front magnetic region A of the magnetic cylindrical member 4, and the coil housing 31. As a result, the movable core 12 of the valve assembly 15 is attracted to the fixed core 5 against the set load of the valve spring 22, and the valve body 18 is separated from the valve seat 8, so that the valve hole 7 is opened and the valve seat member is opened. 3 exits the valve hole 7 and is injected from the fuel injection hole 11 toward the intake valve of the engine.

  At that time, the nonmagnetic region B of the magnetic cylindrical member 4 prevents short-circuiting of the magnetic flux from the fixed core 5 to the front magnetic region A of the magnetic cylindrical member 4, so that a large amount of magnetic flux is generated between the fixed core 5 and the movable core 12. Flows and can generate a strong attraction by magnetic force. Moreover, since the nonmagnetic region B is provided by forming the annular penetration beads 37 and 37 by simple laser irradiation on the single magnetic cylindrical member 4, it is not necessary to use a special nonmagnetic cylindrical member. Reduction in the number of points and simplification of the structure can be brought about, and since it is not necessary to perform a special treatment such as addition of an alloy-forming element, the production is easy and the whole can contribute to cost reduction.

  In particular, such penetration beads 37 and 37 can be simultaneously provided by the same laser welding machine in the laser welding process between the valve seat member 3 and the magnetic cylindrical member 4 and between the magnetic cylindrical member 4 and the fixed core 5. Therefore, the manufacturing of the electromagnetic fuel injection valve V does not increase the number of processing steps, and in combination with the reduction in the number of parts and the simplification of the structure, it greatly contributes to cost reduction.

  In addition, since the nonmagnetic region B of the magnetic cylindrical member 4 is provided by the two penetration beads 37 and 37 located at both ends in the axial direction, the range of the nonmagnetic region B can be determined by selecting the interval between the two penetration beads 37 and 37. Can be set freely. In this case, if the melt bead 37 is formed in the middle of the nonmagnetic region B, the nonmagnetic effect of the region B can be enhanced.

  FIG. 4 is a graph showing a test result of the relationship between the depth of the penetration bead and its nonmagnetic property, in which the horizontal axis indicates the magnetic field strength and the vertical axis indicates the permeability reduction rate. The test was performed on five types of test pieces in which the ratio of the depth of the penetration bead 37 and the thickness of the magnetic cylindrical member 4 and t2 / t1 were different from 5%, 25%, 50%, 75%, and 100%. It was.

  As can be seen from this test result, the permeability decrease rate increases as t2 / t1 increases, but when t2 / t1 exceeds 50%, the increase in permeability decrease rate becomes very slow. In order to reduce welding heat input and suppress thermal distortion of the magnetic cylindrical member 4 as much as possible while increasing the nonmagnetic effect, it is effective to set t2 / t1 to approximately 50%. Actually, in the test piece of t2 / t1 = 50%, the dimensional change due to the penetration bead 37 is about several μm within the allowable range in terms of machining accuracy in both the axial length and the inner diameter, and there is no problem. .

  FIG. 5 is a graph showing the test results of the relationship between the penetration bead width and its nonmagnetic characteristics, in which the horizontal axis indicates the magnetic field strength and the vertical axis indicates the permeability reduction rate. The test was performed on three types of test pieces in which the width w of the penetration bead 37 was different from 0.2 mm, 0.5 mm, and 0.7 mm.

  As can be seen from the test results, a practically sufficient nonmagnetic effect can be obtained when w ≧ 0.2 mm.

  Next, a second embodiment of the present invention shown in FIG. 3 will be described.

  In this second embodiment, the point where the magnetic cylindrical member 4 is formed integrally with the fixed core 5 and the portion of the magnetic cylindrical member 4 where the weld beads 37, 37 are formed to form the nonmagnetic region B are thickened. Is the same configuration as in the previous embodiment, except that it is formed in a thin portion 4a thinner than other portions. In FIG. 3, the same reference numerals are assigned to the portions corresponding to the previous embodiment, and Description is omitted.

  According to the second embodiment, the nonmagnetic characteristics of the nonmagnetic region B are further enhanced by the nonmagnetic effect of the penetration beads 37, 37 and the magnetic path constriction effect of the thin wall portion 4a. The mutual magnetic property can be improved.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, the thin portion 4a of the second embodiment can also be applied to the magnetic cylindrical member 4 of the first embodiment. The magnetic cylindrical member 4 can be made of a martensitic magnetic material. Moreover, the number of the penetration beads 37 for forming the nonmagnetic region B can be freely set according to the required characteristics.

1 is a longitudinal sectional view of an electromagnetic fuel injection valve for an internal combustion engine according to a first embodiment of the present invention. 2 enlarged view of FIG. Sectional drawing corresponding to FIG. 2 which shows 2nd Example of this invention Graph showing the test results of the relationship between the penetration bead depth and its non-magnetic properties Graph showing the test results of the relationship between the penetration bead width and its non-magnetic properties

Explanation of symbols

V ... Solenoid valve (electromagnetic fuel injection valve)
A, C ··· Magnetic region B ··· Nonmagnetic region t1 · Melting bead depth t2 · Thickness 4 of cylindrical member ··· Cylindrical member 4a · Thin portion 37 ··· Blended bead

Claims (3)

In a solenoid valve comprising a hollow cylindrical member (4) having a magnetic region (A, C) and a nonmagnetic region (B) adjacent in the axial direction,
While integrally formed of a magnetic material of the cylindrical member (4), the cylindrical member (4), at least two rows of annular penetration bead by laser irradiation (37), in the axial direction of the cylindrical member (4) A solenoid valve characterized in that a portion of the cylindrical member (4) sandwiched between the penetration beads (37) is formed as a non-magnetic region (B), being formed at intervals . The solenoid valve according to claim 1,
The solenoid valve characterized in that the thickness of the cylindrical member (4) in the non-magnetic region (B) is set to be thinner than the thickness in the magnetic regions (A, C). The solenoid valve according to claim 1 or 2,
The solenoid valve according to claim 1, wherein a depth (t1) of the penetration bead (37) is set to approximately ½ of a thickness (t2) of the cylindrical member (4) .