JPS60153468A - Electromagnetic fuel injection valve - Google Patents

Abstract

PURPOSE:To reduce residual flux in the colliding face between a flat movable core and a magnetic ring, while to shorten the valve-close operating time of flat movable core and to improve the durability by securing a non-magnetic thin plate and hardening the surface more than the basic material. CONSTITUTION:Upon supply of exciting current, the upper face of flat movable core 20 will contact tightly against a non-magnetic thin plate 30 of a magnetic ring 13. Upon interruption of exciting current, magnetic adhering force is reduced because of said plate 30 to eliminate the residual flux abruptly. Consequently, said core 20 will move quickly in the valve-close direction to seat a ball valve body 23 in a valve seat 26 thus to close the fuel injection hole 27 instantaneously. Since said plate 30 is harder than the basic material, abrasion due to collision of the upper face of said core 20 against the lower face of said ring 13 is reduced resulting in improvement of the durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electromagnetic fuel injection valve that supplies fuel pressurized to a constant pressure to an internal combustion engine.

[Technical background of the invention]

In an electromagnetic fuel injection valve, when an exciting current is passed through the electromagnetic coil installed in the housing, a magnetic attraction force is generated, which activates the valve body to open one fuel injection port, and pressurizes the fuel to a constant pressure from this injection hole. It is known that the system injects the fuel that has been

The specific structure of a conventional fuel injection valve will be explained based on FIGS. 1 and 2. FIG. 1 shows the entire cross-sectional structure of an electromagnetic fuel injection valve, and numeral 1 in the figure is a housing. The housing 1 is made of a magnetic material, has a cylindrical outer peripheral wall 2, and is integrally provided with a tubular iron core 4 having a fuel passage 3 along the central axis in the center. A connector pipe 5 is integrally formed at the upper end of the iron core part 4, and this connector pipe 5 is connected to a fuel supply pipe (not shown).
Fuel pressurized to a constant pressure, such as gasoline, is supplied through the fuel supply pipe. A filter 6 is installed in the connector pipe 5 to capture foreign matter mixed in the supplied fuel. Further, an insertion tube 7 is fixed to the inside of the iron core part 4 by caulking, and this insertion tube 7 determines the setting and load of a compression spring 8, which will be described later. It constitutes a fuel passage 3.

An electromagnetic coil 10 wound around a spool 9 is fitted into an annular space surrounded by an outer peripheral wall 2 and an iron core 4 of the housing 1 . The electromagnetic coil 10 is connected to a terminal 11, and this terminal 11 is connected to an electronic control device (not shown) via a wire harness. The electronic control device supplies an exciting current to the electromagnetic coil 10 according to the operating status of the internal combustion engine. The terminal 11 is embedded in a synthetic resin connector 12 that is integrally provided in the housing 1.

A magnetic ring 13, a valve guide member 14, a valve seat body 15, and a nozzle 16 are provided at the lower end of the housing 1. These magnetic ring 13, valve guide member 14, valve seat body 15, and nozzle 16 are stacked one on top of the other in order from the top, and the nozzle 16 located at the lower end is fixed by caulking the lower end 2a of the housing 1. Therefore, each of these members is attached to the housing 1 without moving. An O-ring 17 is provided between the valve seat body 15 and the outer peripheral wall 2 of the housing 1 to maintain liquid tightness.

The magnetic ring 13 is made of a magnetic material such as 13 chrome electromagnetic stainless steel, and is spaced apart from and faces the lower end surface of the spool 9 around which the electromagnetic coil 10 is wound. A space 18 through which the fuel passes is secured between these magnetic resigs 13 and the spool 9, and a through hole 19 formed in the iron core portion 4 of the housing 1 is communicated with this space 18. .

A flat movable core 20 is accommodated between the magnetic ring 13 and the valve guide member 14 so as to be movable in the axial direction of the housing 1. The flat movable core 20 is made of a magnetic material such as 13 chromium electromagnetic stainless steel, and has a substantially circular plate shape. The upper surface of the flat movable core 20 faces the lower surface of the magnetic ring 13, and these surfaces are moved toward and away from each other. A compression spring 8 is provided between the flat movable core 20 and the aforementioned insertion tube 7, and this spring 8 always presses the flat movable core 20 downward. Note that the flat movable core 20 is given an upward pressing force by a leaf spring 21, and is set so that the downward pressing force by the compression spring 8 is greater than the upward pressing force by the leaf spring 21. ing.

A plurality of communication holes 22 are formed in the flat movable core 20, and these communication holes 22 communicate with the cavity 18 through the inside of the magnetic ring 13.

A spherical valve body 23 is integrally joined to the center of the lower surface of the flat movable core 20 by brazing or welding.

The valve guide member 14 provided below the flat movable core 20 has a guide hole 2 in the center having an inner diameter slightly larger than the outer diameter of the spherical valve body 23 and into which the valve body 23 is inserted.
4 are provided. Further, a fuel introduction hole 25 is formed in the valve guide member 14 around the guide hole 24 .

A dome-shaped valve seat 26 is formed in the valve seat body 15 at a position coaxial with the central axis of the spherical valve body 23.
A fuel injection hole 27 is provided at the bottom of the tank 6. This fuel injection hole 27 communicates with the fuel introduction hole 25 of the valve guide member 14, but when the spherical valve body 23 is seated on the valve seat 26, the fuel injection hole 27 is closed.

6- In the electromagnetic fuel injection valve having such a configuration, when no excitation current is supplied to the electromagnetic coil 10,
The pressurized fuel supplied to the connector tube 5 is introduced into the cavity 18 from the fuel passage 3 of the insertion tube 7 through the through hole 19 of the iron core 4, and the pressurized fuel in this cavity 18 is introduced into the cavity 18 by the magnetic ring 13. The inner diameter part and the periphery of the flat movable core 20 and the communication hole 2
2, the fuel is guided to the valve seat 26 via the fuel introduction hole 25 of the valve guide member 14. However, in this case, the flat movable core 20 is pressed downward by the compression spring 8, and the spherical valve body 23 is seated on the valve seat 26, so the fuel injection hole 27 is closed, and the fuel that has reached the valve seat 26 is injected. Not done.

When an excitation current is supplied to the electromagnetic coil 10 via the terminal 11, the electromagnetic coil 10, the outer peripheral wall 2 of the housing 1,
A magnetic path passing through the magnetic ring 13, the flat movable core 20, and the iron core portion 4 is formed, and the flat movable core 20 is attracted to the magnetic ring 13 against the repulsive force of the spring 8. Since the push-up blade of the leaf spring 21 is added, the flat movable core 20 is quickly moved toward the magnetic ring 13 by the magnetic attraction force and the push-up blade of the leaf spring 21. Therefore, the spherical valve body 23 integrated with the flat movable core 2o separates from the valve seat 26 and opens the fuel injection hole 27. Therefore, the pressurized fuel that has been supplied up to the valve seat 26 is injected from the fuel injection hole 27 and supplied through the nozzle 16.

When the supply of excitation current to the electromagnetic coil 10 is stopped, the magnetic path disappears and the flat movable core 20 is pushed by the repulsive force of the sprinkles 8, so the spherical valve body 23 seats on the valve seat 26, and the fuel injection hole 27 to stop the fuel supply.

[Problems with background technology]

In such an electromagnetic fuel injection valve, the electromagnetic coil 1
When energized to 0, the flat movable core 20 is quickly lifted by the magnetic attraction force and the push-up force of the leaf spring 21, so the operating speed in the valve opening direction, that is, the valve opening response speed is fast, resulting in high performance. .

However, conventionally, when the flat movable core 20 is attracted to the magnetic ring 13 by magnetic attraction, the upper surface of the flat movable core 20 collides with the lower surface of the magnetic ring 13, and the mutual collision surfaces come into close contact. When the excitation current to the electromagnetic coil 10 is cut off after this, a magnetic attraction force due to residual magnetic flux remains on the collision surface between the flat movable core 20 and the magnetic ring 13, and therefore the flat movable core 20 is slow to return to the valve closing direction. Become. As a result, the valve closing response speed becomes slow, which causes a problem that the operating performance of the fuel injection valve decreases accordingly.

Further, since the upper surface of the flat movable core 20 does not repeatedly collide with the lower surface of the magnetic ring 13, these collision surfaces are worn out, causing a decrease in durability.

[Purpose of the invention]

The present invention was made based on the above circumstances, and its purpose is to reduce the residual magnetic flux generated at the mutual collision surface between the flat movable core and the magnetic ring, quickly eliminate the attractive force, and improve the flat movable core. The purpose of the present invention is to provide an electromagnetic fuel injection valve that shortens the valve closing operation time and improves durability.

[Summary of the invention]

91 In the present invention, a thin plate made of a non-magnetic material is fixed to at least one of the mutually contacting surfaces of the magnetic ring and the flat movable core by brazing or diffusion bonding, and the surface of the thin plate made of the non-magnetic material is bonded to the surface of the thin plate made of the non-magnetic material. It is characterized by being hardened to a harder level than the base material of the thin plate.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in FIGS. 3 and 4.

In this embodiment, the same members as those shown in FIGS. 1 and 2 are given the same numbers, and the explanation thereof will be omitted.

In this embodiment, a thin plate 30 made of a non-magnetic material such as 5IJS304.5US310S, Ti or a Ti alloy, as shown in FIG. 4, is integrally connected to the lower surface of the magnetic ring 13 by diffusion bonding or brazing. It is.

Such a non-magnetic thin plate 30 is intended to be hardened so that the surface 31 on the collision surface side, that is, on the lower surface side, has a hardness higher than that of the non-magnetic thin plate 30 itself.

10- As a means for hardening the surface 31 of the non-magnetic thin plate 30,
The following method will be adopted.

That is, the non-magnetic thin plate 30 is 5US304.5US
When austenitic stainless steel such as 310S is used, the surface 31 of the nonmagnetic thin plate 30 is hardened by using an ion nitriding method, an ion soft nitriding method, a salt bath nitriding method, a salt bath soft nitriding method, etc. Alternatively, it can be hardened by sulfurization or boron infiltration treatment.

In addition, when Ti or a Ti alloy is used as the non-magnetic thin plate 30, the Ti thin plate surface 30 can be
Titanium nitride can be formed on the T: thin plate surface 31 by forming titanium nitride on the thin plate surface 31 or by heating in a nitrogen atmosphere.

Note that by selecting the heating temperature, time, and atmosphere for the surface hardening treatment, diffusion bonding or brazing of the thin plate 30 made of a nonmagnetic material can be performed at the same time as bonding.

According to such a configuration, when an excitation current is supplied to the electromagnetic coil 10 and the flat movable core 20 is attracted to the magnetic ring 13 by magnetic attraction force, the upper surface of the flat movable core 20 is the non-magnetic thin plate of the magnetic ring 13. Closely followed by 30. When the excitation current is cut off, since the non-magnetic thin plate 30 is present between the magnetic ring 13 and the flat movable core 2°, the magnetic adhesion force is reduced and the residual magnetic flux rapidly disappears. Therefore, the flat movable core 20 receiving the pressing force of the spring 8 is quickly moved in the valve closing direction, and the spherical valve body 23 is seated on the valve seat 26 to instantly close the fuel injection hole 27. This shortens the valve closing operation time, making it possible to improve the performance of the electromagnetic fuel injection valve.

Moreover, since the surface 31 of the non-magnetic thin plate 30 is formed to have a hardness higher than that of the base material of the thin plate, the rate of wear even if the upper surface of the flat movable core 20 collides with the lower surface of the magnetic ring 13 is reduced. , durability is improved.

In the embodiment shown in FIGS. 3 and 4, a non-magnetic thin plate 30 is bonded to the lower surface of the magnetic ring 13, but the present invention has another embodiment shown in FIGS. 5US304.5US310S on the top surface of the flat movable core 20.
, a thin plate 50 made of a non-magnetic material such as Ti or T1 alloy is joined by diffusion bonding or brazing,
Even if the collision surface 51 of the non-magnetic thin plate 50 is hardened, the same effect as in the above embodiment can be obtained.

Furthermore, non-magnetic thin plates may be formed simultaneously on the lower surface of the magnetic ring 13 and the upper surface of the flat movable core 20, respectively.

〔Effect of the invention〕

As described above, according to the present invention, since a non-magnetic thin plate is formed on at least one of the surfaces of the magnetic ring and the flat movable core that collide with each other, the magnetic attraction force is immediately reduced when the excitation current to the electromagnetic coil is cut off. However, since the residual magnetism also disappears quickly, the valve closing operation time of the flat movable core is shortened, thereby making it possible to improve the performance of the electromagnetic fuel injection valve.

Moreover, since the collision surface of the non-magnetic thin plate is hardened to a level higher than the hardness of the thin plate base material, the rate of wear is reduced even if the magnetic ring and the flat movable core are repeatedly collided with each other, thereby increasing durability. will improve.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a conventional electromagnetic fuel injection valve, with FIG. 1 being an overall sectional view, and FIG. 2 being an enlarged sectional view of part 2 in FIG. 3 and 4 show an embodiment of the present invention, with FIG. 3 being an enlarged sectional view of a main part corresponding to FIG. 2, and FIG. 4 being an exploded sectional view of a magnetic ring. 5 and 6 show other embodiments of the invention,
Figure 5 is an enlarged sectional view of the main part corresponding to Figure 2;
The figure is an exploded sectional view of the flat movable core. 1...Housing, 8...Spring, 10...
Electromagnetic coil, 13... Magnetic ring, 15... Valve seat body, 20... Flat movable core, 23... Spherical valve body, 26
...Valve seat, 27...Fuel injection hole, 30.50...
Non-magnetic thin plate, 31.51...Surface hardened part. Applicant's representative Patent attorney Takehiko Suzue 14- Figure 1 Figure 2 Figure 3 Figure 4 031 Figure 5 Figure 6

Claims (3)

[Claims] (1) An electromagnetic coil provided in the housing, a magnetic ring that is magnetized by energization of the electromagnetic coil and becomes a magnetic path, and a flat movable core that is attracted toward the magnetic ring when the magnetic ring is magnetized; A spherical valve body that is fixed to the flat movable core and moves together with the flat movable core, and a valve seat that is attached to the housing facing the spherical valve body and on which the spherical valve body is seated so as to be movable toward and away from the spherical valve body. an electromagnetic fuel injection system comprising: a fuel injection hole formed in the valve seat body and opened and closed by the spherical valve body; and a spring that presses the flat movable core and biases the spherical valve body in a valve closing direction. In the valve, a thin plate made of a non-magnetic material is fixed to at least one of the mutually contacting surfaces of the magnetic ring and the flat movable core by brazing or diffusion bonding. An electromagnetic fuel injection valve characterized by being hardened to a harder level than the base material. (2) The scope of claims characterized in that the thin plate Ti made of the non-magnetic material is made of austenitic stainless steel, and its surface is hardened by nitriding, soft nitriding, sulfurizing, or boron permeation treatment. The electromagnetic fuel injection valve according to item 1. (3) The electromagnetic fuel injection valve according to claim 1, wherein the thin plate made of the non-magnetic material is made of titanium or a titanium alloy, and its surface is hardened by nitriding treatment.