JPH05202823A - Electromagnetic fuel injection valve - Google Patents

Abstract

PURPOSE:To enhance the reliability of a coil by using resin containing a powder- like reinforcing material and adapted to be embedded in the coil so as to reduce a cyclic load exerted to the coil due to a difference in temperature. CONSTITUTION:A coil assembly comprises an exciting coil 2 fixed to the inner part of a fuel injection valve body, and a core 3. A plunger 5 facing the core 3 is attracted toward the core by exciting the coil assembly, and the plunger 5 and the core 3 lift a valve element 3 from a valve seat so that fuel is injected. In particular, resin 1 containing a powder-like reinforcing material is embedded in the outer peripheral part of the exciting coil 2. This resin 1 containing the reinforcing material allows the linear expansion coefficient of the resin to approach that of the coil material. Thereby it is possible to provide a highly reliable injection valve without breakage of coil due to cyclic difference in temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve, and more particularly to an electromagnetic fuel injection valve suitable for a fuel injection valve for an internal combustion engine.

[0002]

2. Description of the Related Art The excitation coil portion of a conventional fuel injection valve has been filled with a resin containing no reinforcing material or a resin containing a reinforcing material having a fibrous directionality.

[0003]

Since the fuel injection valve is used above the engine cylinder, it is used at -40 ° C.
There is a temperature change of from + 130 ° C. Therefore, in FIG. 2, the coil 1 and the embedded resin 2 repeatedly expand and contract depending on the temperature. At that time, when the coefficient of linear expansion of the coil 1 (mainly copper wire) and the coefficient of linear expansion of the resin 2 are different, the coil 1 may be repeatedly subjected to a load due to the difference in the coefficient of linear expansion and may be broken. Especially, when the reinforcing material is not added, the difference is large. For example, copper wire is 1.6 × 10 ⁵ (1 /
℃), 8 × 10 with polyamide resin that does not contain reinforcing material
^A large cyclic load is applied to the copper wire at ⁵ (1 / ° C).

Conventionally, as a countermeasure against this, glass fibers are mixed with the resin 2 to be embedded as a reinforcing material, but in the case of glass fibers, since they are fibrous, the linear expansion coefficient differs depending on the flow direction of the fibers. .. As shown in FIG. 2, the coil is not always in a fixed direction, and there are lines in different directions at the beginning and end of winding of the coil, and the flow direction of the glass fiber contained in the resin is also shown in the figure. There is axial radial flow. In the fiber flow direction, the value is close to the linear expansion coefficient of the copper wire, and the cyclic load is small, but in the direction perpendicular to the flow, the linear expansion coefficient is large compared to the copper wire, and a large cyclic load is applied to the coil.

An object of the present invention is to provide a highly reliable fuel injection valve by using a resin which does not apply a large repetitive load to a coil portion even under a use environment condition where a temperature change is large.

[0006]

To achieve the above object, the present invention uses a resin containing a powdery reinforcing material as a resin for embedding a coil.

[0007]

With the resin containing the powdery reinforcing material, the linear expansion coefficient of the resin can be made close to that of the coil material, and the direction of the linear expansion coefficient can be eliminated, so that a large cyclic load is applied to the coil. There is no need to pay.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The magnetic circuit is composed of a fixed iron core (core) 3, a case 4, and a plunger 5. Inside the core 3, the plunger 5
A spring 9 that presses a valve body including a ball valve 6 against the seat surface 8 of the nozzle 7, a spring adjuster 10 that adjusts the load of the spring 9, and a fuel that prevents the fuel from flowing out from a gap between the core 3 and the adjuster o A ring 11 is provided. Further, between the core 3 and the case 4, an o-ring 1 for preventing the fuel from flowing out from the gap between the exterior molding resin 1 and the core 3 and the exterior molding resin 1 and the case 4.
3, 14, a coil 2 wound around a bobbin 12 for exciting a magnetic circuit is provided. This coil 2 is embedded with a resin called exterior molding resin 1. The case 4 is provided with an o-ring 15, a fuel passage 16, a filter 17 on the outer periphery thereof, a stopper 18, and a nozzle 7 having a swirler 19 for guiding the ball valve 6 therein. Further, a terminal 20 for transmitting a signal to the coil 2 and a yoke mold 21 surrounding the terminal and forming a connector are provided on the outer periphery of the case 4. The valve body has a plunger 5, a ball valve 6, and a guide ring 22 formed integrally, and the guide ring 22 is guided by the inner diameter of the core 3. The nozzle 7 is provided with a swirler 19 for guiding the ball valve 6 and giving a swirling force to the fuel, and an o-ring 23 on the outer circumference of the nozzle.

Based on the above structure, the operation of the injection valve will be described. When an electric signal is applied to the coil 2, a magnetic circuit is formed by the core 3, the case 4 and the plunger 5, and the plunger 5 is attracted to the core 3 side. The plunger 5 is integrally connected to the ball valve 6, and when the plunger 5 moves, the ball valve 6 also moves and separates from the seat surface 8 of the nozzle 7 to open the valve. The fuel is pressurized and adjusted by the fuel pump and the fuel pressure regulator, flows into the inside of the injection valve, and is supplied to the seat portion. The fuel supplied to the seat is swirler 1
A swirling force is applied by 9 and is injected through the orifice 24.

Since this injection valve is in the vicinity of the cylinder of the engine, it receives heat from the engine in addition to changes in temperature.
It is exposed to repeated temperature differences of about -40 ° C to + 150 ° C. At that time, the coil part is embedded (mold) on the outside of the coil with a resin having a linear expansion coefficient different from that of the coil.
Repeated load is applied due to the difference in linear expansion coefficient. conventionally,
As the exterior molding resin, a polyamide resin containing no reinforcing material or a polyamide resin containing a glass fiber reinforcing material has been used. However, in that case, the coil may be broken due to a large difference in the coefficient of linear expansion or the directionality of the reinforcing material as described above. When the wire breakage occurs, the injection valve does not operate, which causes malfunction of the engine rotation and reduction of the output. In the present invention,
The problem was solved by using a resin containing a powdery reinforcing material as the exterior molding resin. Since it is in the form of powder, there is no directionality of the linear expansion coefficient, and the linear expansion coefficient can be brought close to that of the copper wire of the coil. One example thereof is a polyamide resin containing a powdery reinforcing material, a polyphenylene sulphite resin, or an epoxy resin.

[0011]

As described above, according to the present invention, it is possible to provide a highly reliable injection valve which does not cause coil breakage due to repeated temperature differences.

[Brief description of drawings]

FIG. 1 is a sectional view of an injection valve according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a coil part according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Exterior molding resin, 2 ... Coil, 3 ... Core, 4 ... Case, 12 ... Bobbin.

Claims (4)

[Claims] 1. A movable iron core (hereinafter referred to as a plunger) having an exciting coil fixed inside an injection valve main body and a coil assembly including a fixed iron core, and facing a fixed iron core (hereinafter referred to as a core). ) Is attracted to the core side by exciting the coil assembly, and the fuel is injected by removing the valve provided on the side opposite to the core of the plunger from the valve seat. In the fuel injection valve, an electromagnetic fuel injection valve characterized in that the outer periphery of an exciting coil is embedded with a resin containing a powdery reinforcing material. 2. An electromagnetic fuel injection valve according to claim 1, wherein the outer periphery of the exciting coil is filled with a polyamide resin containing a powdery reinforcing material. 3. The electromagnetic fuel injection valve according to claim 2, wherein the outer periphery of the exciting coil is filled with polyphenylene sulfite resin containing a powdery reinforcing material. 4. The electromagnetic fuel injection valve according to claim 2, wherein an outer periphery of the exciting coil is filled with an epoxy resin containing a powdery reinforcing material.