JP2508744B2 - Solenoid valve for fuel injection device - Google Patents

Description

The present invention relates to a fuel injection device for a diesel engine, and relates to a fuel injection device for a diesel engine, in which a high-pressure fuel pressurized by a fuel injection pump or a unit injector is set at an arbitrary predetermined timing for each operation cycle of the engine. The present invention relates to a solenoid valve for controlling the fuel injection amount or the injection rate by overflowing to the low pressure side.

"Prior Art" The concept of an injection amount control system in which high pressure fuel is directly overflowed by a solenoid valve is well known from Japanese Patent Publication No. 51-34936. In the above method, an electromagnetic valve is provided in the passage communicating between the pump pressurizing chamber and the low pressure side, and the electromagnetic valve is applied after an arbitrary predetermined time or a cam angle has elapsed from the signal of the reference angle sensor that generates a signal at a predetermined time during the pump operation cycle. By opening the valve, high pressure fuel is made to overflow and the fuel injection amount is controlled.
Compared to a conventional mechanical governor that positions a rack or sleeve to control the fuel injection amount, the mechanism is much simpler and suitable for electronic control.

The problem with the above high pressure overflow method is at least 200 to 400 kg.
A reliable, compact and inexpensive solenoid valve that withstands the injection pressure of diesel injection pumps and unit injectors that reach / cm ² and maintains the closed valve, and operates with a response of up to 200 Hz according to the engine speed. The point is how to realize it. Further, the solenoid valve is a mechanism that is closed when an electric signal is not applied due to a failure such as disconnection, stops fuel injection, operates to safely stop the vehicle, and closes when energized, that is, normally. Must be provided with an opposite operating direction to the fluid control valve of. JP-A-61-226529 has been proposed as a solenoid valve having a high-speed response, but this solenoid valve has a complicated mechanism and is large and expensive.

Further, in the solenoid valve disclosed in U.S. Pat. No. 4,568,021, the housing of the solenoid is arranged in contact with the injector body with a bolt. Since the high-pressure fuel pressurized by the plunger also pressurizes the housing of the electromagnetic solenoid, the bolt is tightened with an extremely high torque. However, since the housing of the conventional electromagnetic solenoid is molded into a cup shape with a synthetic resin material, the housing is large to withstand high torque, that is, strong axial force. Since the generated magnetic flux leaks to the outside and a strong attractive force cannot be obtained, there is a problem that high speed operation cannot be performed.

"Problems to be Solved by the Invention" The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a small electromagnetic valve for a fuel injection device that can operate at high speed. To aim.

"Means for Solving Problems" The present invention employs the following technical means in order to achieve the above object.

That is, according to the present invention, there is provided a solenoid valve (100) for opening and closing the high pressure fluid passages (2, 3) of the fuel injection device, the winding (103k) and the core (103i) contained in the housing (103m). And an electromagnetic solenoid portion (103) that forms a magnetic pole by energizing the winding (103k), and is disposed on one side of the magnetic pole formed by the electromagnetic solenoid portion (103). An armature (102) that moves by forming a magnetic circuit with the core (103i).
a) and a valve section (102) having a valve member (102g) connected to the armature (102a), the housing (103m) of the electromagnetic solenoid section (103)
Is composed of a high-strength ferromagnetic material, and at least the inner surface of this housing (103m)
It is characterized in that a metal thin film (103n) made of a material having a low specific resistance is formed.

"Operation" In the electromagnetic valve that opens and closes the high-pressure fluid passages (2, 3) of the fuel injection device, since high-pressure fluid pressure acts,
The housing (103m) is assembled with fastening members such as bolts due to high axial force. Therefore, it is preferable that the housing (103m) is made of a steel material having high strength.

However, if the housing (103m) is made of a steel-based high-strength metal material as described above,
m) will be composed of ferromagnetic material, so the winding (103
Magnetic flux generated by energizing (k) (magnetic flux 103 in Fig. 5-2)
Y) leaks to the housing (103m) side, the amount of effective magnetic flux to be passed in the axial direction of the armature (102a) decreases, and the suction force of the armature (102a) decreases.

However, according to the present invention, as shown in FIG. 5-2, when the magnetic flux 103Y is generated around the winding (103k) due to the energization of the winding (103k), the bottom specific resistance is accompanied with it. The eddy current 103X flows in the metal thin film (103n) made of the above material so as to prevent the magnetic flux 103Y.

Then, due to the eddy current 103X, a magnetic flux is generated in the metal thin film (103n) in the direction opposite to the magnetic flux 103Y, and
The magnetic flux generated in n) acts as a magnetic shield on the inner surface of the housing (103m) and prevents the magnetic flux 103Y from the winding (103k) from leaking to the housing (103m) side.

As a result, the magnetic flux 103Y can be effectively passed in the axial direction of the armature (102a), and the effective magnetic flux amount passing through the armature (102a) can be increased.
It is possible to provide a solenoid valve having a small size and a high response.

[Embodiment] According to a preferred embodiment of the present invention, the metal thin film (103n) can be formed of copper, silver, aluminum or the like, in which copper is a material having a low specific resistance. At the same time, it can be obtained at a relatively low cost and is easily processed, which is convenient for forming the metal thin film (103n).

Further, the housing (103m) is formed into a substantially bottomless tubular shape or a bottomed tubular shape, and the metal thin film (103n) is formed on the surface of the housing (103m) by plating. As a result, the metal thin film (103n) can be efficiently formed on the housing surface by a simple process such as plating.

The reference numerals of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments described later.

"Example" An example of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a sectional view of a solenoid valve which is an embodiment. solenoid valve
As shown in FIG. 2, 100 is installed downstream of the high pressure passage 2 that communicates with the high pressure chamber 203 of the injection pump or the unit injector. The overflow passage 3 communicates with the low pressure chamber 207. The solenoid valve 100 has a substantially cylindrical rotationally symmetric shape, and the valve portion 102 and the solenoid solenoid portion, which are the main components.
An integral solenoid valve is formed by putting 103 and spacer ring 104 in casing 101 and assembling taning ring 106.

The valve portion 102 is configured such that the seated shaft 102g is passed through the seat spacer 102f, and the stopper 102e is screwed into the seat 102b, and the shim 102c, the spring 102d, the stopper 102e, the seat spacer 102f, and the seated shaft are inserted into the valve housing 102b from the bottom.
102g is inserted, an amateur 102a is screwed onto the upper part of the shaft 102g, and a sleeve 102h is fitted and inserted into the seated shaft 102g. The seated shaft 102g has a seat that comes into oil-tight contact with the seat spacer 102f in the lower part, the center part is a bearing shaft that slides with the valve housing 102b, and the upper part has a smaller diameter than the shaft diameter with which the armature 102a is screwed. Is provided, and a screw having a diameter larger than the shaft diameter is provided near the seat below the bearing shaft portion, and the stopper 102e is screwed into the screw. Further, the outer diameter of the lowermost seat portion is slidably inserted into the sleeve 102h, and an oil passage E is provided in the center portion. Spring 102d
The assembled amateur 102a, stopper 102e, and shaft with seat 102g are urged downward, and the passage opening of the seat is normally open, and the high pressure passage 2-passage passage-passage passage passage -Passage D-The overflow passages 3 are connected in this order. Here, in this example, the seated shaft 102g constitutes the valve member of the valve portion 102.

In FIG. 1, the electromagnetic solenoid portion 103 shows a cross section in which the right half cross section is rotated 90 degrees with respect to the left half cross section. The resin case 10 in which two terminals 103a of ± 2 poles are integrally molded is shown.
3c, the first O-ring 103d, the second O-ring 103e, the resin spacer 103h, the laminated E core 103i, and the resin bobbin 103j.
Assemble the coil wound 3k, connect the terminal 103a and the winding 103k by resistance welding or soldering, insert them into the bottomless cylindrical housing 103m from the bottom and inject the filling resin 1031 such as epoxy to solidify. It is configured. As shown in FIG. 5-2, the inner surface of the housing 103m is coated with a copper thin film 103n by a plating process. High-strength ferromagnetic material such as high-strength copper, alloy steel, or tool steel is used for the housing 103m. The shoulder portion A of the housing 103m forms a spherical surface and is in contact with the retaining ring 106 at this portion, and the backup ring 103f and the third O-ring 103g are inserted between the housing 103m and the casing 101. There is. The terminal 103a is partially made of a plate-shaped metal as shown in FIG. The laminated E core 103i is formed by laminating E-type iron plates. The resin bobbin 103j has a wall-shaped shoulder portion at the B portion, and the terminal 103a and the film wire 103k at the C portion.
Insulation is performed between the winding exposed at the joint portion (soldering or the like) and the laminated E core 103i.

"Operation" Based on the above configuration, when a high frequency current is applied to the terminal 103a of the solenoid valve, a fifth coil is formed around the winding 103k.
As shown in FIG. 2, an axial bundle 103Y is generated, and at the same time, an eddy current 103x flows in the thin copper winding 103n of the housing 103m so as to prevent the magnetic flux 103Y from being generated. Then, due to the eddy current 103x, a magnetic flux is generated in the copper thin film 103n in the direction opposite to the magnetic flux 103Y,
The magnetic flux 103Y generated in the winding 103k is prevented from leaking out of the housing 103m which is a ferromagnetic material and the housing 103m. Therefore, the magnetic flux 103Y generated in the winding 103k effectively passes in the axial direction of the amateur 102a, is effectively used as the attraction force of the amateur 102a, and attracts the amateur 102a.
Since the stopper 102e is distant from the electromagnetic solenoid 103 in terms of distance, it does not generate a magnetic attraction force. Because the suction force overcomes the spring 102d because it is integrated with the amateur 102a and the shaft with seat 102g.
102a and the shaft with seat 102g are sucked upward to close the passage opening. The pressure in the toe portion is the same as the pressure in the upper and lower passages of the shaft 102g with seats, which is communicated by the passage E. Therefore, if the terminal 103a is energized while the high pressure passage 2 is in a high pressure state, the passage opening is closed and the high pressure passage 2 is kept at high pressure. Next, when the power supply to the terminal 103a is stopped, the armature 102a and the seated shaft 102g are moved downward by the force of the spring 102d, and the passage opening is opened.

The operation of the fuel injection pump or the unit injector equipped with the solenoid valve 100 described above will be described.

FIG. 2 is a schematic view showing a single cylinder by simplifying the entire structure of the fuel injection device.

The plunger 201 of the fuel injection pump or unit injector 200 pumps the fuel previously sucked into the pump chamber 203 by the action of the cam 202. In the pressure stroke of the cam 202, the fuel in the pump chamber 203 is injected from the injection nozzle 206 toward the engine fuel chamber (not shown) through the discharge valve 204 and the steel pipe 205. On the other hand, the pump chamber 203 communicates with the overflow passage 3 and the low pressure pump housing chamber 207 via the solenoid valve 100 via the high pressure passage 2. Therefore, if the solenoid valve 100 is opened during the fuel injection, the high-pressure fuel quickly overflows into the overflow passage 3 and the fuel injection ends. The opening / closing control of the solenoid valve 100 is performed by an electronic control unit 208 equipped with a microcomputer. A reference signal is input to the electronic control unit 208 at each pump bottom dead center by a pulser 209 and a reference signal detector 210 that are mounted coaxially with the cam 202.

FIG. 3 is a timing chart showing the operation, in which (a) is the lift amount of the plunger 201, (b) is a reference signal, (c) is an energizing pulse to the solenoid valve 100, and (d) is an injection nozzle. The injection rate from 206 is shown.

When the electronic control unit 208 converts the rotation angle into a time in the electronic control unit 208 every time a certain engine rotation angle elapses and the solenoid valve 100 is opened after the time T elapses, the high pressure fuel overflows. The sink fuel injection stops. Solenoid valve 100
The fuel injection amount Q is controlled by changing the valve opening timing of. Then, after a predetermined time t, the solenoid valve 100 is energized again to close the valve and prepare for the next injection.

As described above, the solenoid valve according to the present invention is characterized in that the solenoid valve opens when the electrical connection is stopped. Therefore, when a failure occurs in the wiring connecting the electronic control unit 208 and the solenoid valve 100, the solenoid valve 100 remains open and all the high pressure fuel in the plunger chamber 203 overflows into the overflow passage 3. It is not injected, the engine is stopped and the vehicle is safely stopped. That is, the disconnection failure acts on the safe side (fail safe). When a solenoid valve that opens when energized is used, it is not preferable because the solenoid valve remains closed when the wire is disconnected and a large amount of fuel corresponding to the amount of plunger lift may be injected.

[Advantages of the Invention] As described above, since the electromagnetic valve of the present invention has the above-described configuration, the metal thin film having a low specific resistance formed on the inner surface of the housing acts as a magnetic shield, and the magnetic flux generated by the electromagnetic solenoid is generated. Can be effectively prevented from leaking to the housing side of the ferromagnetic body. Therefore, it is possible to increase the attractive force of the amateur with an increased amount of effective magnetic flux passing in the axial direction of the amateur, so that it is possible to obtain a small-sized solenoid valve excellent in high response, and a metal thin film with low specific resistance. Is formed in the shape of a film on the inner surface of the housing, the amount used is very small, and the housing can be made of inexpensive iron-based metal, so the material cost is relatively low.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a sectional view of a solenoid valve, FIG. 2 is a schematic view of a fuel injection device, FIG. 3 is a timing diagram for explaining the operation, and FIG. 4 is FIG. Of the electromagnetic solenoid of FIG. 5, FIGS. 5-1 and 5-2 are explanatory views of the housing of FIG. 2 ... High pressure passage, 3 ... Overflow passage, 100 ... Solenoid valve, 101
…… Casing, 102 …… Valve part, 102a …… Amateur, 1
02b …… valve housing, 102c …… shim, 102d …… spring, 102e …… stopper, 102f …… seat spacer, 102g …… seat shaft, 102h …… sleeve, 103 …… electromagnetic solenoid, 103a …… terminal , 103b
...... Nut, 103c …… Resin case, 103d …… 10th ring, 103e …… 20th ring, 103f …… Backup ring, 10
3g …… 3rd O-ring, 103h …… resin spacer, 103i …… multilayer E core, 103j ……
Resin bobbin, 103k ... Winding, 103l ... Filling resin, 103m ...
… Housing, 103n… Copper thin film, 104… Spacer ring, 106… Retaining ring, 107… External seal O-ring, 108… Spring washer.

Claims (3)

(57) [Claims] 1. A solenoid valve (100) for opening and closing a high pressure fluid passage (2, 3) of a fuel injection device, wherein a winding (103k) and a core (103i) enclosed in a housing (103m). And an electromagnetic solenoid portion (103) that forms a magnetic pole by energizing the winding (103k), and is disposed on one side of the magnetic pole formed by the electromagnetic solenoid portion (103). (103i) and the armature (102) that moves by forming a magnetic circuit.
a) and a valve section (102) having a valve member (102g) connected to the armature (102a), the housing (103m) of the electromagnetic solenoid section (103)
Is made of a ferromagnetic material having high strength, and a metal thin film (103n) made of a material having a low specific resistance is formed on at least the inner surface of the housing (103m). Solenoid valve. 2. The solenoid valve for a fuel injection device according to claim 1, wherein the metal thin film (103n) is made of copper. 3. The housing (103m) is formed into a substantially bottomless cylindrical shape or a bottomed cylindrical shape, and the metal thin film (103n) is formed on the surface of the housing (103m) by plating. Claims 1 or 2
An electromagnetic valve for a fuel injection device according to the item.