JPH1054324A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability, responsiveness and dimensional accuracy and stably accurately control a flow amount relating to various fuels. SOLUTION: In a movable core 36 integrally moved with a valve unit 39 and a fixed core 8, a movable stopper 41 and a fixed stopper 20 of high hardness made of non-magnetic material are additionally provided. At operation time, one end face of the two stoppers 20, 41 is made to butt against partly one more end face, by preventing direct butt of an end face of the two cores 8, 36, durability and responsiveness are improved. Dimensional accuracy is obtained by a mounting position of the fixed stopper 20, a stroke of the valve unit 39 is fixed.

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 which controls fuel supplied to an engine by an electric signal and injects the fuel into an intake pipe.

[0002]

2. Description of the Related Art When an electric signal sent from an electronic control unit is energized in accordance with the operating state of an engine, the valve is opened by an electromagnetic force when energized, and the valve is closed by the spring force of a return spring when not energized. In the fuel injection valve that injects a required amount of fuel into the intake pipe by repeating the above operation, the operation time by the electric signal is set to the unit of 0.001 to 0.01 seconds. Therefore, in order to achieve the purpose of accurately controlling the fuel flow rate by repeating the operation in such a very short time, the fuel injection valve itself needs to have excellent durability, high responsiveness, and high dimensional accuracy. As is well known in the art.

[0003] Referring to Fig. 1 showing an embodiment of the present invention, the actual situation of durability, responsiveness and dimensional accuracy will be described. First, regarding the durability, the fixed core 8 and the movable iron core 36 are different from each other. It is made of a material close to pure iron because it uses a ferromagnetic material.Because of its low hardness, it is easily deformed when it is directly hit when energized. The stroke of the iron core 36 changes, and the fuel flow rate changes.

[0004] Next, as for the response, the movable iron core 36 and the valve body 39 held in the floating state at the center of the leaf spring-like elastic holder 28 as shown in the figure show that the valve body 39 slides. However, if the fixed iron core 8 and the movable iron core 36 are directly abutted, magnetic flux remains when power is not supplied, resulting in a response delay.

As one of these measures, a fixed iron core 8 is used.
The surface of the butted portion of the armature 36 and the movable core 36 is coated with a high-hardness non-magnetic material such as chromium by plating, welding, etc. And the responsiveness can be improved by eliminating the residual magnetic flux.

However, since the high-hardness material is attached to the entire surface of the abutting portion with a uniform thickness, there is a disadvantage that a loud collision sound is generated during operation. In addition, when applied to a system that is currently being developed for the practical use of injecting gas fuel such as LPG instead of gasoline, the oil and tar components contained in the gas fuel adhere and adhere to the fuel. It has been found that there is an inconvenience of causing a response delay at the time of non-energization.

Further, regarding the dimensional accuracy, in order to accurately control the fuel flow rate, it is necessary to make the stroke and opening and closing of the valve body 39 accurate. The accuracy of the distance A between the contact surface S that regulates the mounting position and the distal end surface of the fixed core 8 and the degree of concentricity B between the outer case 1 and the fixed core 8 are particularly important.

However, the outer case 1, the fixed core 8, the valve seat 31, the spacer plate 24, and the movable core 36, which are components, are provided.
It is extremely troublesome to precisely control all the dimensions of the valve body 39, and it is unavoidable to increase man-hours and costs. Therefore, an attempt was made to form the outer case 1 and the fixed core 8 into an integral product by casting and obtain the accuracy of A and B by cutting, but according to this method, the outer case 1 was fixed.
Since the inside of the machine is cut with high precision, it did not lead to reductions in man-hours and costs. In addition, as described above, the coating of a high-hardness material by plating, welding, or the like has a limitation in improving the accuracy because accurate dimensional control of the coating thickness is impossible.

[0009]

As described above, the present invention requires that the fuel injection valve be excellent in all of durability, responsiveness, and dimensional accuracy in order to perform accurate fuel flow control. Nevertheless, conventional countermeasures generate loud collision noise, have limitations on applicable fuels, cannot be provided at low cost due to man-hours and costs, and have a limit in improving accuracy. It tries to solve the point that is left.

[0010]

According to the present invention, there is provided a movable iron core having a fixed core and a coil holder supported on a base end of an outer case and a valve seat body supported on a distal end of the outer case. Are arranged in front of the fixed iron core with their end faces facing each other.When the coil is energized, the valve body separates from the seat surface of the valve seat by electromagnetic force, and when the coil is not energized, the valve body is brought into contact with the seat surface by the spring force of the return spring. In order to solve the above-mentioned problem, a fuel injection valve having a close contact structure is configured as follows.

That is, a fixed core is fitted around a high hardness fixed stopper made of a non-magnetic material and supported by the outer case, and a high hardness movable stopper made of a non-magnetic material is supported by the movable core. The end faces of the two cores and the end faces of the two stoppers face each other in an exposed state, and the end faces of the cores have a gap when the end faces of the stoppers come into contact with each other.

According to this configuration, deformation due to direct contact of the fixed iron core and the movable iron core is prevented, the durability is improved, and the response delay due to the residual magnetic flux is eliminated, and the control of the fuel flow rate becomes accurate.

When one end face of the two stoppers is in contact with a part of the other end face, the contact area between them is small, so that the collision noise is small and the adhesive force due to oil and tar is reduced. Since it is small and does not cause a response delay, gas fuel can be applied.

Further, when the fixed stopper is set with the mounting position of the valve seat body to the outer case and the concentricity of the fixed iron core with the outer case, the dimensional control of each part is simplified,
The valve stroke can be set to a high dimensional accuracy with a small number of man-hours and costs, and the fuel flow rate can be controlled more accurately.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. An outer case 1 has an end cover 3 integrally formed at the base end of a cylindrical case main body 2 and a distal end formed at the front end. A thin holding cylinder 4 is integrally provided, and a front end of the case main body 2 forms an annular contact surface 5.

On the center axis of the outer case 1, a branch passage 12 is provided near the tip end and is open to the outer peripheral surface, and has a fuel passage 11 penetrating forward and backward. The intermediate part is inserted and held. The distal end of the fixed iron core 8 has a slightly smaller diameter to form a stepped portion 9, and an end surface 8 a on the distal end side projects slightly forward from the contact surface 5. A joint pipe 13 having a fuel filter 14 is screwed to a base end projecting rearward from the end cover 3.

Further, a coil holder 16 holding a coil 15 is inserted into the outer case 1, and O-rings 17, 18,
The fixed core 8 and the coil holder 16 are fixed by the holding ring 19.
Are concentrically arranged and supported by the outer case 1.

Next, a fixed stopper 20, a spacer plate 24, an elastic holder 28, and a valve seat body 31, each having an outer diameter equal to the inner diameter of the holding cylinder 4, are stacked on the contact surface 5 in this order and are the same as the fixed iron core 8. These are arranged on the central axis, and the outer case 1 and the outer case 1 are fixed to each other by crimping the crimping portion 6 at the tip of the holding cylinder 4 to the outer peripheral edge on the tip side of the valve seat body 31.

The fixed stopper 20 is formed in a disk shape, has a holding hole 21 at the center, and has a plurality of through holes 2 around it.
The fixed core 8 is held on the central axis of the outer case 1 by tightly fitting the step 9 to the holding hole 21,
The distal end face 8a is the distal end face 2 of the fixed stopper 20.
0a and are aligned on the same plane.

The spacer plate 24 is also formed in a disk shape, and has a center hole 2 slightly larger in diameter than the end face 8a of the fixed iron core 8.
5 and a plurality of through-holes 26 therearound, and the front surface is concave except for the outer peripheral edge.

The elastic holder 28 is a thin disk-shaped spring member in which three fuel passage holes 29 each formed of a spiral arc-shaped slot are provided at a phase of 120 degrees with each other. The device is pulled and supported in three directions having a phase of 120 degrees to operate stably on the central axis.

Except for the outer peripheral portion, the valve seat body 31 has a concave surface at the proximal end and a valve passage 32 at the center, and a seat surface 33 at the proximal end protrudes into the concave portion.
In addition, an injection nozzle 34 communicating with the valve passage 32 is attached to a distal end protruding from the distal end surface of the case body 1.

At the center of the elastic holder 28, a movable iron core 36 having a disk shape and slightly smaller than the center hole 25 of the spacer plate 24, and a valve element superposed on the front surface, 39 are arranged. The Y-shaped movable stopper 41 has the same groove 3 formed in the movable core 36.
7, and its proximal end surface 41 a slightly protrudes from the proximal end surface 36 a of the movable core 36. A threaded support shaft 43 projecting from the center of the valve body 39 penetrates through the centers of the elastic holder 28, the movable iron core 36, and the movable stopper 41, and these are integrated with each other by a nut 44 screwed into the shaft end. It is stuck to. The movable stopper 4
A return spring 46 made of a compression coil spring fitted into the outlet portion of the fuel passage 11 is in contact with the base end surface of the fuel cell 11.

The elastic holder 28 is provided with a valve chamber 45 formed by an opposed recess formed between the spacer plate 28 and the valve seat 31.
The valve body 39 is displaced in the center axis direction inside the
3 or separate from it. During this time, the movable iron core 36 is fitted in the center hole 25 in a non-contact state.

Fixed stopper 20 and movable stopper 41
Is made of a non-magnetic material, for example, SUS304 which has been subjected to a nitriding treatment. In this case, it is possible to form the material with high precision by a cutting process and to obtain a high hardness without changing the dimensions.

The space between the joint pipe 13 and the valve chamber 45 according to the present embodiment having such a configuration is filled with fuel adjusted to a predetermined pressure.

When a drive signal is sent from the electronic control unit to the coil 15 in accordance with the operating state of the engine,
The magnetic core 36 is attracted to the fixed core 8 by the magnetic flux flowing through the magnetic circuit including the outer case 1, the spacer plate 24, the movable core 36, and the fixed core 8 when the power is supplied, and the movable stopper 41 is abutted against the fixed stopper 20. Valve body 3
Numeral 9 moves integrally with the movable iron core 36, moves away from the seat surface 33, and injects fuel in the valve chamber 45 from the valve passage 32 and the injection nozzle 34 into the intake pipe of the engine. Return spring 4 when not energized
With the spring force of 6, the valve body 39 comes into close contact with the seat surface 33 to stop fuel injection. The above operation is repeated for each pulse of the electric signal, and the fuel injection amount is controlled by the energization time, that is, the valve opening time, as in the conventional case.

According to the present embodiment, the distal end faces 8a, 20a of the fixed core 8 and the fixed stopper 20 are aligned on the same plane, and the proximal end face 41a of the movable stopper 41 is the proximal end face of the movable core 36. The end faces 8a, 36a of the two iron cores 8, 36 are separated without contact when the two stoppers 20, 41 are abutted, since they protrude slightly from the end 36a. That is, the high hardness stoppers 20 and 4
Due to the abutment of 1, deformation does not occur, excellent durability is obtained, and since there is no change in stroke due to deformation and no response delay due to residual magnetic flux, it is possible to accurately control the fuel flow rate.

Further, according to the present embodiment, the movable stopper 41 is formed in a Y-shape and has a small contact area with the fixed stopper 20, so that not only the collision noise generated during operation is small, but also the oil contained in the fuel, Even if the tar component adheres, it is easily separated by the spring force of the return spring 46, and does not cause a response delay when power is not supplied.

The movable stopper 41 has a cross shape, an I shape,
Any shape such as an arc shape that contacts a part of the end surface 20a of the fixed stopper 20 can be used. Further, the end surface 20a of the fixed stopper 20 may be slightly protruded from the end surface 8a of the fixed core 8, and the end surface 20a of the fixed stopper 20 may abut a part of the end surface 41a of the movable stopper 41.

Next, according to the present embodiment, regarding the dimensional accuracy required to make the stroke of the valve element 39 accurate and to perform the fuel flow control accurately, according to the present embodiment,
4, dimensions and contact surface 5 of valve seat body 31 and end surface 8 of fixed iron core 8
Even if the dimension A of the fixed stopper 20 is not precisely controlled, the mounting position of the valve seat body 31 can be properly adjusted by adjusting the depth of the holding hole 21 of the fixed stopper 20 into the step 9 by tight fitting. As a result, the stroke of the valve body 39 can be made accurate. The fixed iron core 8 has a fixed stopper 2
By fitting into the holding hole 21 of 0, the concentricity B with the outer case 1 is obtained.

The present invention can be applied to a fuel injection valve which does not have the elastic holder 28 and in which the valve body 39 is held on the center axis by a sliding portion.

[0033]

As described above, the fixed stopper and the movable stopper made of a high-hardness non-magnetic material are attached to the fixed iron core and the movable iron core, and the two stoppers are abutted during operation to make the iron core non-contact. According to the present invention,
The durability is improved, the response delay is eliminated, and the fuel flow rate can be stably and accurately controlled.

When one end face of the two stoppers is in contact with a part of the other end face, the collision noise during operation is reduced and not only liquid fuel but also gas fuel is properly injected. It becomes possible.

Further, by adjusting the mounting position of the fixed stopper, the mounting position of the valve seat body can be made appropriate without accurately controlling the dimensional accuracy of each part, and the fuel stroke of the valve body can be made accurate. The controllability of the flow rate can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged partial view of FIG. 1;

FIG. 3 is a sectional view taken along line XX of FIG. 1;

FIG. 4 is a sectional view taken along the line YY of FIG. 1;

[Explanation of symbols]

1 outer case, 5 contact surface, 8 fixed iron core, 16 coil holder, 20 fixed stopper, 24 spacer plate, 28 elastic holder, 31 valve seat, 33 seat surface,
36 movable iron core, 39 valve body, 41 movable stopper, 4
6 Return spring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F16K 31/06 385 0380-3K F16K 31/06 385A

Claims (3)

[Claims] 1. A fixed core and a coil holder are supported on a base end side of an outer case, and a valve seat body is supported on a distal end side. A movable core with the valve body fixed thereto is provided in front of the fixed core. The end faces are arranged so as to face each other, and when the coil is energized, the valve body is separated from the seat surface of the valve seat body by electromagnetic force, and the valve body is brought into close contact with the seat surface by the spring force of the return spring when the coil is not energized. In the fuel injection valve, a high-hardness fixed stopper made of a non-magnetic material is supported by the outer case by fitting the fixed iron core at the center, and a high-hardness movable stopper made of a non-magnetic material Are supported by the movable core, the end faces of the two cores and the end faces of the two stoppers face each other in an exposed state, and the end faces of the core contact the end faces of the stoppers. A fuel injection valve having a clearance; 2. The fixed stopper and the movable stopper,
The fuel injection valve according to claim 1, wherein one end face is formed so as to be in contact with a part of the other end face. 3. The fuel injection valve according to claim 1, wherein the fixed stopper sets a mounting position of the valve seat body to the outer case and a concentricity of the fixed iron core with the outer case.