JPS6337262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic valve, and more particularly to an electromagnetic fuel injection valve suitable for use in a fuel injection device for an internal combustion engine.

Embodiments of the present invention will be described in detail below based on the drawings. Note that the same reference numerals in the drawings indicate the same members. Figure 1 shows, for example,
An example of a conventional electromagnetic fuel injection valve as seen in Publication No. 60426 is shown. In the figure, reference numeral 10 denotes a case, and inside the case 10, a coil 14 is wound around a yoke 12.

Furthermore, a core 18 is disposed at the center of the coil 14 and has a fuel introduction pipe 16 fixed therein.

Further, a nozzle 22 having an ejection hole 20 is fixedly installed at one end of the case 10. Further, a plunger 24 that is driven by an electromagnetic force generated when the coil 14 is energized is provided adjacent to one end of the core 18, and the plunger 24 has an opening area of the jet hole 20 at its tip. A rod 28 with a needle 26 is connected thereto.
The rod 28 is provided with a collar 30 for restricting the movement of the plunger 24 in the valve opening direction, and is configured such that the movement of the plunger 24 is stopped by contact with a stopper 32.

Further, a compression spring 34 is provided between the fuel introduction pipe 16 and the plunger 24, and a pressing force is always applied to the plunger 24 in the left direction in the figure, so that the plunger 24 is in a closed state.

Further, a filter 36 is provided on the fuel supply side of the fuel introduction pipe 16.

In the above configuration, when a control signal is input to the terminal 38 from an external control device (not shown), the coil 14
is biased, and the plunger 24 attracts against the pressing force of the compression spring 34.

On the other hand, since pressurized fuel is fed into the gap between the inner peripheral wall of the nozzle 22 and the needle 26 via the filter 36 and the fuel introduction pipe 16, the electromagnetic force generated by the energization of the coil 14 causes the plunger 24 to move. When driven to the right in the figure, the nozzle 2
0 is opened and a predetermined amount of fuel is injected from the injection port 20.

In the conventional electromagnetic fuel injection valve described above, the needle must be in close contact with the inner peripheral wall of the nozzle, so the needle must be made long, which increases the weight of the moving part of the plunger, and Deterioration in the responsiveness of the solenoid valve to the control signal supplied from the solenoid valve cannot be avoided.

Furthermore, in order to maintain close contact between the needle tip and the seat of the nozzle, these parts require strict processing precision.

The purpose of the present invention is to reduce the weight of the movable parts of an electromagnetic fuel injection valve to improve the responsiveness of valve operation, and to improve the sealing degree of the valve part without requiring high processing accuracy for the guide part of the valve body. The purpose of the present invention is to provide an electromagnetic fuel injection valve that can control the timing.

A feature of the present invention is that the valve body is made of a spherical body, and a part of the spherical body is sunk into a recess in an annular part formed at the tip of the shaft of the movable plunger, and in this abutting part. By joining the two parts by welding, it is possible to easily align the axis of the movable plunger with the center of the valve body, improve the adhesion of the valve part, and reduce the weight of the plunger's movable part. .

FIG. 2 shows an embodiment of an electromagnetic fuel injection valve according to the present invention. In the figure, a coil 14 wound around a concentric cylindrical yoke 12 is provided inside a case 10 made of a magnetic material, and fuel flows through the center of the coil 14. A core 18 to which a fuel introduction pipe 16 is fixed is provided.

On the other hand, a nozzle 42 having an ejection hole 42a at its tip and a spherical valve seat 42b at the other end is fixed at the end of the case 10. A fuel introduction hole 42c is provided in the valve seat portion 42b.
The fuel introduction hole 42c and the ejection hole 42a are configured to communicate through a passage 42d.

Further, a plunger 24 is provided opposite the end of the core 18, and a grip portion 46 for holding a spherical valve body 44 is formed at the tip of a rod 28 integrally formed with the plunger 24. ing. The grip portion 46 and the valve body 44 are joined by welding.

Here, the edges 18a, 18a of the front core 18 are tapered. This is done by reducing the weight of the moving parts of the solenoid valve in order to increase the response speed of the solenoid valve, and by reducing the outer diameter of the plunger 24 and reducing the cross-sectional area of the core 18 in order to increase the electromagnetic force generated by the coil 14. This is due to the need to make it sufficiently large.

For this purpose, the core 18 is
Therefore, the amount of magnetic flux leaking from the end face of the core 18 adjacent to the end face of the plunger 24 increases, and the effective magnetic flux decreases, and this is to be prevented.

The grip portion 46 and the valve body 44 are joined by welding. The plunger 24 is normally connected to a compression spring 34 provided between the plunger 24 and the fuel introduction pipe 16.
The solenoid valve is in a closed state because it is pressed to the left in the figure by the pressing force.

In addition, a control signal is sent to the terminal 38 by an external control device.
When the input is made, the electromagnetic force generated by the coil 14 attracts the plunger 24 to the right in the figure, but the stopper 32 provided on the case 10
The plunger 24 is brought into contact with the gripping portion 46.
movement is stopped. The amount of lift of the valve body 44 is determined by the gap between the grip portion 46 and the stopper 32 when the coil 14 is not energized.

Next, main parts of the present invention are shown in FIGS. 3 and 4. A gripping portion 46 formed at the tip of the rod 28
has an annular end and a recess in the center. The spherical body (ball) serving as the valve body 44 is brought into contact with the holding portion 46 so that a portion thereof is sunk into the recess of the holding portion 46 .
It is welded to the annular part of No.6. in this way,
When the valve body 44 is joined with a portion sunk in the recess, the axis of the plunger 24 and the center of the valve body 44 can be easily aligned, and the valve body 44 can be accurately attached to the valve seat portion 42b. Can be seated. Note that the valve body 44 and the grip portion 46 are joined to each other on the plunger side from the maximum diameter position of the ball. For this welding, in order to avoid thermal deformation, resistance welding is most suitable because it causes less temperature rise in areas other than the welded area and is inexpensive. In particular, when hardened steel is used for the ball, resistance welding facilitates post-heat treatment and prevents weld cracking.

Further, the valve body 44 and the valve seat portion 42b are made of hardened steel to improve wear resistance, and for example, a material having a Rockwell hardness of H _RC 30 or more is used. Here, the spring pressure of the compression spring 34 cannot be strong enough due to the responsiveness of the solenoid valve, so the valve body 44 and the valve seat 42
The circularity of b is required to be 1 micron or less. In this connection, use a ball that can easily form an accurate sphere.

On the other hand, the plunger 24 is made of electromagnetic soft iron or Si-containing iron alloy, which has good direct current magnetic properties, and is coated with chrome plating or plastic coating on the outer periphery to improve sliding wear resistance.

The valve body 44 is configured to be guided by a petal-shaped notch 48 provided at the other end of the nozzle 42 and an annular locking member 50. In this manner, the valve body 44 is guided at two locations: the side of the ball and the outer periphery of the plunger 24, so that the valve operation is performed smoothly.

That is, if the valve body is guided only by the plunger, the valve body will not come into accurate contact with the valve seat unless there is some play, and conversely, the valve will not operate smoothly if there is some play. Therefore, it is necessary to guide the side part of the ball used as the valve body, but it is easy to achieve coaxiality between the guide part on the side part of the ball and the valve seat part, and some play between the ball and the guide part is allowed. Therefore, the ball does not interfere with accurate contact with the valve body by guiding as described above.

As described above, according to the present invention, it is possible to obtain an electromagnetic fuel injection valve with improved responsiveness without requiring high machining accuracy for the guide portion of the valve body.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view showing the structure of a conventional electromagnetic fuel injection valve, FIG. 2 is a partially cutaway sectional view showing an embodiment of the electromagnetic fuel injection valve according to the present invention, and FIGS. 4 shows the main parts of the embodiment shown in FIG. 2, FIG. 3 is a partially enlarged sectional view showing the structure of the valve body and the guide part, and FIG. 4 is a sectional view taken along the line A--A in FIG. 3. 10...Case, 12...Yoke, 14...Coil, 16...Fuel introduction pipe, 18...Core, 2
0,42a...Ejection hole, 22...Nozzle, 24...
... Plunger, 26 ... Needle, 28 ... Rod, 34 ... Compression spring, 38 ... Terminal, 40 ...
Passage, 42b...valve seat, 42c...fuel introduction hole, 42d...passage, 44...valve body, 46...grip, 48...notch.

Claims (1)

[Scope of Claims] 1. An excitation coil, a movable plunger that reciprocates in the axial direction of the case within a case formed of a magnetic material surrounding the outer periphery of the excitation coil, and a movable plunger disposed at the center of the excitation coil, one end of which is disposed at the center of the excitation coil. a hollow cylindrical core adjacent to an end face perpendicular to the axis of motion of the movable plunger; a fuel introduction pipe fixedly installed inside the core through which fuel flows; and a core perpendicular to the axis of motion of the movable plunger In the electromagnetic fuel injection valve, the electromagnetic fuel injection valve includes a compression spring provided between the movable plunger and the movable plunger, and a valve body formed at the tip of the shaft of the movable plunger. An electromagnetic fuel injection valve characterized in that a part of the sphere is brought into contact with a recess of an annular part formed at the tip of the shaft, and the two are joined by welding at the corresponding contact part. 2. The electromagnetic fuel injection valve according to claim 1, wherein the welded portion between the valve body and the shaft tip of the movable plunger is located closer to the plunger than the maximum diameter position of the valve body. 3. The electromagnetic fuel injection valve according to claim 2, wherein the valve body and the valve seat on which the valve body is seated are made of a material having a Rockwell hardness of H _RC 30 or higher. 4. The electromagnetic fuel injection valve according to claim 2 or 3, wherein the valve body and the shaft tip of the movable plunger are welded by resistance welding. 5. By making the outer diameter of the core larger than the outer diameter of the movable plunger and tapering the end of the core near the end face perpendicular to the axis of motion of the movable plunger, the outer diameter of the end face of the core is made larger than the outer diameter of the movable plunger. The electromagnetic fuel injection valve according to any one of claims 1 to 4, characterized in that the diameter is approximately the same as the diameter of the electromagnetic fuel injection valve.