JPH0244048Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to an electromagnetic fuel injector mainly used in an electronically controlled fuel injection device for an internal combustion engine (hereinafter also referred to as engine) for automobiles.

(Prior art) Conventionally, in the electromagnetic fuel injector seen in Utility Model Application Publication No. 58-72454, etc., as shown in Fig. 3 and Fig. 4, which is an enlarged view of the main part, a cylindrical ferromagnetic material is used. A casing 1 is divided into a front section 1a and a rear section 1b by a partition wall 2 having a communication port in the center.
It is divided into 3 is the valve housing,
It is fitted and fixed to the front section 1a via an annular stopper 4 inserted in contact with the partition wall 2, and a fuel injection port 5 is provided at the tip. 5a is a valve seat. 6 is an on-off valve, valve housing 3
It is inserted reciprocally into a guide hole 3a provided in the guide hole 3a. A valve element 6a is provided at the tip of the on-off valve 6, and a movable iron core 7 is coupled to the rear end. A fixed core 8 is arranged in the rear section 1b facing the movable core 7, and an electromagnetic coil 9 is wound around the outer periphery of the fixed core 8. A return spring 10 is inserted between the movable iron core 7 and the fixed iron core 8, and biases the on-off valve 6 to close the fuel injection port 5 while the electromagnetic coil 9 is not energized. 8a is a fuel passage, and a strainer 11 is inserted into the entrance of the passage.
A cylindrical spring seat 12 that supports a return spring 10 is fitted and fixed in the center. Reference numeral 13 denotes a terminal through which a control signal is input to the electromagnetic coil 9.

In the electromagnetic fuel injector configured as described above, when the electromagnetic coil 9 is excited by energization, as shown by the solid arrow in FIG. , a magnetic flux passes through a magnetic path formed by a loop of the fixed core 8, and an attractive force acts between the movable core 7 and the fixed core 8. This suction force overcomes the force of the return spring 10 and displaces the on-off valve 6, thereby opening the fuel injection port 5 and injecting pressurized fuel.

(Problems to be Solved by the Invention) However, according to the above-described conventional electromagnetic fuel injector, the spring seat 12 is generally made of SUM22 (sulfur composite free-cutting steel) or the like. Here, SUM22 is a magnetic material.
Therefore, a part of the magnetic flux generated by the excitation of the electromagnetic coil 9 is transmitted to the fixed core 8, the spring seat 12, the return spring 10, the movable core 7, the space B, and the casing as shown by the broken line arrow in FIG. 1. It also passes through a magnetic path made up of a loop of fixed iron core 8.

That is, originally, by passing from the fixed core 8 through the space A and through the movable core 7, a part of the magnetic flux that provides an attractive force between the two 8 and 7 becomes so-called leakage flux, which causes the fixed core 8, the space A, and the movable core to become leakage flux. 7 and passes through the spring seat 12 and return spring 10.

Therefore, the magnetic flux generated by the excitation of the electromagnetic coil 9 does not work efficiently as an attractive force between the fixed iron core 8 and the movable iron core 7.

Also, as a material for the spring seat 12
There is a method of using SUS304 (austenitic stainless steel). However, although SUS304 is not a magnetic material, its machined surface has a magnetic property, and this residual magnetism causes harmful magnetic flux that creates an attractive force between the fixed core 8 and the movable core 7. There are drawbacks.

Based on the above knowledge, the present invention aims to prevent part of the magnetic flux originally required to obtain the attractive force between the fixed iron core and the movable iron core from flowing out as leakage magnetic flux from the regular magnetic path. Furthermore, the problem to be solved is to prevent the generation of harmful magnetic flux due to machining residual magnetism, etc.

(Means for solving the problem) The above problem is solved by an electromagnetic fuel injector having a structure in which the fuel injection port 22 is opened by separating the on-off valve 24 from the valve seat 22a by electromagnetic means. The movable iron core 2 attached to the on-off valve 24
5, a fixed core 8 that has a surface facing the movable core 25 and is immovable relative to the valve seat 22a, and a fixed core 8 that is provided around the fixed core 8 and extends substantially perpendicularly to the surface. An electromagnetic coil 9 that provides magnetic flux is interposed between the movable iron core 25 and the fixed iron core 8, so that the on-off valve 24 comes into contact with the valve seat 22a when the electromagnetic coil 9 is de-energized. It has a return spring 10 that biases the return spring 10, and a spring seat 26 for supporting one end of the return spring 10, and the spring seat 26 is made of a non-magnetic material and is not magnetized by processing. The invention is solved by an electromagnetic fuel injector characterized in that it is made of non-containing materials.

(Function) In the electromagnetic fuel injector according to the present invention, the spring seat 2 of the return spring 10 interposed between the fixed iron core 8 and the movable iron core 25
6 is made of non-magnetic material.

Therefore, the magnetic resistance of the spring seat 26 is large, and the magnetic resistance of the spring seat 26 is large.
6. Almost no magnetic flux passes through the route leading to the return spring 10 and the movable iron core 25. Therefore, when the electromagnetic coil 9 is excited, most of the magnetic flux is directly transmitted from the fixed iron core 8.
It passes through a magnetic path leading to the movable iron core 25 separated by space.

Furthermore, since the spring seat 26 is made of a material that is not subject to magnetization due to machining, no harmful magnetic flux is generated due to machining residual magnetism.

(Example) This invention will be described below based on drawings showing examples. FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injector according to this invention. Components that are the same as those in the prior art are designated by the same numbers as in FIG. 3, and explanations thereof will be omitted. 21 is a valve housing, and a fuel injection port 22 is provided at the tip. An adapter 23 is attached to the outside of the fuel injection port 22, and a valve seat 22a is formed inside. Reference numeral 24 denotes an on-off valve, which is inserted into a guide hole 21a provided in the valve housing 21 so as to be able to reciprocate. A spherical valve element 24a is provided at the tip of the on-off valve 24,
A movable iron core 25 is coupled to the rear end. The movable core 25 is always urged forward by the return spring 10 supported by the spring seat 26. The spring seat 26 in this invention is made of a non-magnetic material such as aluminum, brass, etc., which does not become magnetized by processing. This prevents the generation of a harmful magnetic path as shown by the broken line arrow in FIG. 4 and residual magnetism that attracts the on-off valve when the valve is not energized.

(Effects of the invention) As explained above, this invention is used in electromagnetic fuel injectors for automobiles, etc., in which the spring seat of the return spring of the on-off valve is made of a non-magnetic material and a material that is not subject to magnetization during processing. As a result, as shown in FIG. 2, the harmful magnetic path including the spring seat is eliminated, the magnetic flux density of the magnetic flux flowing through the normal magnetic path is increased, and the responsiveness of the opening/closing valve is improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of this invention, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a longitudinal sectional view of a conventional electromagnetic fuel injector, and Fig. 4 is a longitudinal sectional view of the conventional electromagnetic fuel injector. It is an enlarged view of the main part. 1... Casing, 1a... Front section, 1b...
... Rear compartment, 2 ... Bulkhead, 8 ... Fixed iron core, 9 ...
...Electromagnetic coil, 10...Return spring,
21...Valve housing, 22...Fuel injection port, 21a...Guide hole, 24...Opening/closing valve, 25
...Movable iron core, 26...Spring seat.

Claims (1)

[Claims for Utility Model Registration] An electromagnetic fuel injector having a structure in which a fuel injection port 22 is opened by separating an on-off valve 24 from a valve seat 22a by electromagnetic means, Movable iron core 2 attached to valve 24
5, a fixed core 8 that has a surface facing the movable core 25 and is immovable relative to the valve seat 22a; An electromagnetic coil 9 that provides a magnetic flux of It has a return spring 10 that biases the return spring 10, and a spring seat 26 for supporting one end of the return spring 10. An electromagnetic fuel injector characterized in that it is manufactured from a material that is not susceptible to damage.