JPS6329106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic fuel injector mainly used in a multi-point or single-point electronically controlled fuel injection device for an internal combustion engine (hereinafter also referred to as engine) of an automobile.

Conventionally, an electromagnetic fuel injector 1 has a fuel injection port 3 at the tip of a valve housing 2, as shown in FIG. An armature 6 is connected to the rear end of the on-off valve 5, a fixed magnetic core 8 and an electromagnetic coil 9 are attached to the rear inside of the magnetic housing 7 that holds the valve housing 2, and a control signal is input from a terminal 10 to open and close the valve. The valve 5 is moved back and forth to inject pressurized fuel.

The inside of the fuel injection port 3 of the valve housing 2 forms a valve seat 3a (see FIG. 2) that contacts the valve element 5a of the on-off valve 5, and a fuel passage 4 continues behind it.
The cylindrical inner surface serves as a guide hole for the on-off valve 5. The front part of the valve housing 2 is the cover 7
a, and the rear part is connected to the magnetic housing 7 via an O-ring 11 on the side surface and a spacer 12 on the rear end surface.
is fixed to the front of the A pintle 19 (see FIG. 2) is provided at the tip of the valve 5a, and an umbrella portion 19a for diffusing fuel is formed at the tip. A flange 5b is provided on the rear circumference of the on-off valve 5, and a spacer 1 is provided at the rear limit of the reciprocating stroke.
Contact with the front surface of 2. The magnetic housing 7 is a yoke made of ferromagnetic material, and an electromagnetic coil 9 is attached to the space between the magnetic housing 7 and the fixed magnetic core 8 via sealing O-rings 13 and 14. The fixed magnetic core 8 is also made of ferromagnetic material, and has a fuel passage 15 passing through its axial center. A compression spring 16 is inserted into the front end of the fuel passage 15 and constantly pushes the rear end surface of the armature 6 forward to hold the on-off valve 5 in the closed position. 17 is compression spring 1
This sleeve forms the fixed seat of No.6. Fuel passage 15
A fuel filter 18 is provided at the rear end of the fuel filter 18 .

In such an electromagnetic fuel injector 1, it is necessary that the on-off valve 5 reciprocates smoothly, and that the valve element 5a contacts the conical valve seat 3a without a gap to seal high-pressure fuel. For this reason, the sliding parts and the fuel passage/guide hole 4 provided on the front and rear outer peripheries of the on-off valve 5 are required to have high machining accuracy, and the valve seat 3a and valve element 5a are required to have a high degree of surface roughness and roundness. , it is necessary to keep the coaxiality within a very narrow range. Further, the tip shape of the on-off valve 5 including the pintle 19 and its bulk portion 19a must be formed into a complicated shape in order to atomize the fuel. Moreover, since the guide hole 4 and the on-off valve 5 are made of stainless steel, it is even more difficult to process them. Therefore, the manufacturing cost of these products has become extremely high.

In addition, since the integrated weight of the on-off valve 5 and armature 10 of the conventional electromagnetic fuel injector 1 is relatively heavy (about 5 g), the responsiveness of the on-off valve 5 that corresponds to turning on and off the electromagnetic coil 9 is not very good. Moreover, since the impact force is large, the on-off valve 5 is likely to wear out. Furthermore, for the purpose of stabilizing the idling speed and reducing the fuel consumption rate, it is required to shorten the time it takes for the on-off valve 5 to stabilize when the valve is opened and closed. To achieve the above, it is effective to reduce the mass of the on-off valve 5 and the armature 10, but in order to maintain the accuracy of the sliding parts, the diameter of the on-off valve 5 cannot be made too thin, and the axis of the guide hole 4 In order not to increase the inclination of the axis of the on-off valve 5 with respect to the center, the length of the on-off valve 5 cannot be made too short. Therefore, it has not been easy to realize an electromagnetic fuel injector in which the on-off valve 5 has high responsiveness and good wear resistance.

In order to solve the above-mentioned problems, the present invention aims to provide an electromagnetic fuel injector that has sufficiently high operating characteristics with reduced machining accuracy, and at the same time has a lighter on-off valve and improved response characteristics. shall be.

The present invention will be explained below based on drawings of embodiments. In FIG. 3, 21 is an electromagnetic fuel injector according to the present invention. Reference numeral 22 denotes a valve housing, which has a fuel injection port 23 at its tip and a guide hole 24 passing through its axial center. 31 is a plunger type on-off valve, which is slidably inserted into the guide hole 24, and has an armature 34 at its rear end.
are combined. Fuel injection port 23 and guide hole 24
A fuel chamber 24a is formed between the front end and the front end of the fuel chamber 24a.
Magnetic housing 27, fixed magnetic core 28, electromagnetic coil 29, terminal 30, O-rings 36, 37, 3
8 and the fuel filter 39 have the same structure as the conventional one. A space in which the armature 34 reciprocates is provided between the rear end of the valve housing 22 and the front end of the fixed magnetic core 28, and the armature 34 is surrounded by a fuel passage 27a. Fixed magnetic core 28
A fuel passage 25 passes through the axial center of the armature 34, and a compression spring 26 is inserted into the front end thereof to constantly push the rear end surface of the armature 34 forward and hold the on-off valve 31 in the closed position. 25a is a compression spring 26
This is a sleeve that forms the fixed seat of the

The details of the on-off valve 31 are as shown in FIG. 4, in which two spheres 32 and 33 with the same radius are fixed by welding or W, and an armature 34 is attached to one end on the axis connecting their centers, that is, to the rear end of the sphere 33. Welding etc. W
It is combined with . A large circular portion of each of the spheres 32 and 33 perpendicular to the axis of the on-off valve 31 is a sliding portion 32 that supports the on-off valve 31 in contact with the inner surface of the guide hole 24.
a, 33a. These sliding parts 32
a, 33a are arranged almost equally on the circumference,
At least two or more communication grooves 32b and 33b are provided by cutting out the spherical surface and allowing fuel to communicate with each other. The front spherical surface of the sphere 32 is
When the on-off valve 31 is in the closed position, it is pressed by a spring 26 to a valve seat 23a provided in a conical shape inside the injection port 23, forming a valve element 32c that seals high-pressure fuel. The rear end surface of the armature 34 has a required thickness in order to provide a certain gap between it and the front end surface of the fixed magnetic core 28 to the extent that it is not affected by the residual magnetism of the fixed magnetic core 28 when the on-off valve 31 is in the open position. A spacer 35 made of a non-magnetic material and having a length L is bonded. When the on-off valve 31 is in the closed position, the distance between the rear end surface of the spacer 35 and the front end surface of the fixed magnetic core 28 is determined to be the full stroke D of the on-off valve 31.

As described above, the on-off valve 31 configured by fixing two spheres with the same radius can easily have the same sliding portions 32a and 33a at the front and back along the reciprocating axis, thereby making the on-off valve 31 It slides accurately along the guide hole 24 to enable uniform jet formation. In other words, the factors that improve the jet flow characteristics of spherical valves are:
On the valve seat side, the coaxiality and roundness of the injection port, the squareness of the end face of the injection port, the cylindricity and roundness of the guide hole, and on the valve side, the roundness and cylindricity of the outer shape, the guide hole diameter and the outside of the opening/closing valve. Clearance with diameter,
One example is the squareness of the armature. In this invention, by adopting a ready-made ball with high sphericity, the above-mentioned factors on the valve side can be easily satisfied, and the overall length of the on-off valve can be shortened.
The cylindricity and roundness of the guide hole, which are factors on the sheet side, are also easily satisfied. Further, since the valve portion 32c has a spherical surface, it has a self-aligning function, so that processing accuracy can be reduced. Furthermore, due to the simplified structure, the manufacturing process for the on-off valve is approximately half that of the conventional one.

Relaxation of processing accuracy for the above two spherical configuration,
From the viewpoint of self-alignment, weight reduction, etc., an on-off valve composed of a single sphere may be considered. That is, there is no sliding part, and the sphere is fixed to a flat armature and held by a flexible holding member, and the injection port is opened and closed by pressing or separating the spherical valve element from the conical valve seat. However, with this configuration, the operation of the flexible holding member is not sufficiently stable, and the uniformity of jet flow formation is inferior to that of conventional on-off valves.

Further, a structure in which three or more spheres of the same shape are connected and fixed is not advantageous because it is difficult to form sliding parts in three or more straight lines and requires very advanced processing technology.

Electromagnetic fuel injector 21 configured as described above
The pressurized fuel is sent through the fuel filter 39 and passes through the fuel passages 25, 27a, 24 and the communication grooves 33b, 32b of the on-off valve 31 to the fuel chamber 24.
It is supplied up to a. Since the on-off valve 31 is pressed by the compression spring 26, it normally keeps the fuel injection port 23 closed. When a valve opening time signal is input to the electromagnetic coil 29 from a control computer (not shown), a magnetic field is generated in the magnetic housing 27 and the fixed magnetic core 28, the armature 34 is attracted, and the on-off valve 31 integrated therewith is retracted. However, a gap is created between the valve seat 23a and the valve element 32c, and the pressurized fuel in the fuel chamber 24a flows into the fuel injection port 23.
is injected from.

When the on-off valve 31 is operated, the fuel injection port 23
Even if there is a slight deviation between the axes of the guide hole 24, the contact surface of the valve element 32c against the valve seat 23a is spherical, so the pressing force of the compression spring 26 will cause the contact surface of the valve element 32c to As the valve moves, an alignment action is automatically activated, and a pressing force that is uniform on the circumference is applied between the valve seat 23a and the valve element portion 32c, resulting in a complete sealing action.

The weight of the on-off valve 31 including the armature 34 is
It is extremely lightweight, weighing approximately 2g, which is significantly lighter than the conventional on-off valve 5, which weighs approximately 5g.
Responsiveness to control signals is greatly improved.
In the fuel injection characteristics shown in FIG. 5, compared to the conventional characteristics (dashed line in the figure), the characteristics according to the present invention have improved linearity in the low speed and high speed regions, as shown by the solid line. As a result, the idling speed of the engine can be lowered, and the maximum speed can be increased to increase the output of the engine.

As explained above, this invention utilizes advanced processing technology for an electromagnetic fuel injector by creating an on-off valve in which two spheres with the same radius and an armature are connected and fixed on one axis. A sliding part that enables smooth reciprocating motion without runout can be obtained without the need for such an arrangement, and the effect is that uniform jet formation can be easily obtained.

Furthermore, the spherical valve element provides a self-aligning function, which has the effect of making it possible to achieve a high valve closing function while reducing machining accuracy.

Furthermore, since the structure of the on-off valve is simplified and the weight thereof is reduced, the responsiveness of the on-off valve is increased and the fuel injection characteristics are improved.

Furthermore, since the machining accuracy is relaxed and the structure is simplified, manufacturing costs can be reduced and the electromagnetic fuel injector can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a conventional electromagnetic fuel injector, FIG. 2 is an enlarged explanatory view of the fuel injection port portion of FIG. 1, FIG. 3 is a vertical cross-sectional view of an electromagnetic fuel injector according to the present invention, and FIG. The drawings are detailed views of the on-off valve shown in Fig. 3, and Fig. 5 is an explanatory view of its operation. 2, 22... Valve housing, 3, 23...
...Fuel injection port, 4, 24...Guide hole, 5, 31
...Opening/closing valve, 32, 33... Sphere, 32a, 33
a...Sliding part, 32b, 33b...Communication groove, 6,
34... Armature.

Claims (1)

[Claims] 1. An electromagnetic fuel injector for an internal combustion engine that injects pressurized fuel by reciprocating an on-off valve connected to an armature within a guide hole in response to a signal input to an electromagnetic coil, wherein the on-off valve has two parts of the same radius. The large circular part of each sphere, which is perpendicular to the axis connecting their centers, forms a sliding part in contact with the guide hole. Fuel grooves are arranged equally and communicate from front to back, and the armature is connected to one end on the axis, and the other end forms a valve that contacts a valve seat inside the fuel injection port. electromagnetic fuel injector.