JPH06207568A - Fuel injection valve and manufacture of fuel injection valve - Google Patents

Abstract

PURPOSE:To provide a fuel injection valve to stabilize fuel flow rate characteristics and manufacture of the fuel injection valve. CONSTITUTION:A throttle part 3c in a protrusion conical shape is arranged downstream from a valve element 3b. The apex angle of the throttle part 3c is equal to the apex angle alpha of a valve seat 1b in a recessed conical shape formed in a nozzle 1. A throttle part 3c is formed such that, during closing, the throttle part is spaced away from the valve seat 1b with a gap part 50 with a specified width therebetween. Since a passage the width of which is kept at a constant value in the direction of the flow of fuel is formed between the throttle valve 3c and the valve seat 1b, during opening, the flow of fuel is stabilized with the occurrence of disturbance. As a result, stable fuel flow rate characteristics are provided. Further, since the throttle part 3c in a protrusion conical shape is spaced away from the valve seat 1b by the gap part 50 of a specified width H therebetween, the valve element part 3b approximately in a spherical shape is caused to seat on the valve seat 1b in a state to be brought into linear contact with the valve seat, during closing resulting in ensurance of sealing ability.

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,
In particular, the present invention relates to a fuel injection valve used for supplying ignition fuel to an internal combustion engine of an automobile and a manufacturing method thereof.

[0002]

2. Description of the Related Art In general, a fuel injection valve has a nozzle having a fuel injection hole and a concave conical valve seat, and a substantially spherical valve element having a movable iron core at one end and a valve seat seated at the other end. And a plunger rod provided with, and by applying an electromagnetic force to the movable iron core, the plunger rod slides to adjust the injection amount from the fuel injection hole. Further, in the fuel injection valve as described above, Japanese Utility Model Publication No. 2-38820 proposes to provide a convex conical throttle portion integrally with the valve portion on the downstream side of the valve portion. In this known technique, when the apex angle of the valve seat portion of the nozzle is θ1 and the apex angle of the convex cone shape of the throttle portion is θ2, the throttle portion is formed so that θ1 <θ2, whereby the fuel is heated to a high temperature. Even if it becomes, the flow rate of the injected fuel will not decrease so much, and it is said that there is an effect that the air-fuel mixture having a stable air-fuel ratio can be supplied to the engine.

Further, as described in Japanese Utility Model Publication No. 2-38820, conventionally, a plunger rod is generally connected to a movable iron core and a sphere which is a separate member serving as a valve member coaxially with the movable iron core. It was Therefore, in the case of attaching a convex conical throttle portion to the valve portion as in Japanese Utility Model Publication No. 23820,
(1) Whether the tip of the fuel downstream side of the seal portion of the joined valve part is processed into a convex cone shape, or (2) whether the convex cone shaped part of another member is joined to the fuel downstream end of the valve portion. Either way.

Further, in the fuel injection valve, in order to obtain the stroke accuracy of the plunger rod, it is necessary to secure a distance from the valve element portion to the thrust surface in contact with the stopper. After joining the child parts, the thrust surface was processed based on the valve part.

[0005]

However, the prior art has the following problems. Conventionally, the valve portion of the fuel injection valve has a substantially spherical shape as described above. In this case, on the downstream side of the contact portion of the valve portion with the valve seat, the passage formed between the valve portion and the valve seat has a shape in which the flow passage area sharply expands in the fuel flow direction. Therefore, the fuel flow in this portion becomes unstable during fuel injection, and stable fuel flow rate characteristics cannot be obtained. Here, the fuel flow rate characteristic refers to the reproducibility of the fuel injection amount for one pulse of the same pulse width, which is uniquely determined under a constant condition of the type and temperature of the fuel.
This is the same with the known technique described in Japanese Utility Model Publication No. 23820/1990. That is, in this known technique, since the apex angle θ2 of the convex cone shape of the plunger rod is larger than the apex angle θ1 of the valve seat portion, the flow passage area is similarly expanded and the fuel flow rate characteristic becomes unstable.

Further, in the known technique disclosed in Japanese Utility Model Publication No. 23820/1990, the movable iron core is connected to the movable iron core and a sphere which is a separate member serving as a valve member. In the case of, the coaxiality between the movable iron core and the valve portion cannot be ensured, and in the case of (2), the coaxiality between the valve portion and the convex conical shape cannot be ensured further. Therefore, the sealability is not ensured and the fuel flow rate characteristic becomes unstable.

Further, since the valve part of another member is connected to the movable iron core, even if the thrust surface is machined with reference to the valve part thereafter, the distance from the valve part to the thrust surface can be accurately made constant. It was difficult to do so, and the stroke of the plunger rod varied. Therefore, the opening area of the valve at the time of opening the valve varies, the metering accuracy is reduced, and the fuel flow rate characteristic becomes unstable.

A first object of the present invention is to provide a fuel injection valve capable of stabilizing the fuel flow rate characteristic and a method of manufacturing the fuel injection valve.

A second object of the present invention is to provide a fuel injection valve capable of stabilizing the fuel flow rate characteristic by stabilizing the flow of fuel downstream of the contact portion between the valve element portion and the valve seat. Is.

A third object of the present invention is to improve the coaxial accuracy of the movable iron core, the valve portion and the conical throttle portion, thereby stabilizing the fuel flow rate characteristic and the fuel injection valve. Is to provide a method for manufacturing the same.

A fourth object of the present invention is to provide a method of manufacturing a fuel injection valve capable of stabilizing the fuel flow rate characteristic by improving the stroke accuracy of the plunger rod.

[0012]

In order to achieve the above first and second objects, according to the present invention, a nozzle having a fuel injection hole and a concave conical valve seat, and a movable iron core at one end are provided. And a plunger rod having a substantially spherical valve element seated on the valve seat at the other end, and the plunger rod slides by applying an electromagnetic force to the movable iron core, and from the fuel injection hole. In the fuel injection valve that adjusts the injection amount of
The valve portion has a convex conical throttle portion having the same apex angle as the concave cone shape of the valve seat downstream of the contact portion of the valve portion with the valve seat. A fuel injection valve is provided in which a passage having a constant width is formed in a fuel flow direction between a throttle portion and the valve seat.

[0013] Preferably, in the fuel injection valve, there is provided the fuel injection valve, wherein the throttle portion is formed so as to be separated from the valve seat with a gap portion having a constant width when the valve is closed.

Further, in order to achieve the first to third objects, preferably, in the fuel injection valve, the movable iron core, the valve element portion and the throttle portion are all integrally formed of the same material. A fuel injection valve is provided.

More preferably, in order to achieve the first to third objects, in the method of manufacturing a fuel injection valve, the movable core, the valve portion and the throttle portion are integrally formed of the same material. Further, there is provided a method for manufacturing a fuel injection valve, characterized in that the valve portion is processed by using the convex conical shape of the throttle portion as a center.

Further, preferably, in order to achieve the first to fourth objects, in the method of manufacturing the fuel injection valve,
The plunger rod has a thrust surface that comes into contact with a stopper that determines the stroke end of the plunger rod, and the valve element and this thrust surface are cut from a diagonal side of the plunger rod with a single grindstone to simultaneously perform cylindrical grinding. Provided is a method for manufacturing a fuel injection valve, which is characterized by being processed.

In order to achieve the above first and third objects, the present invention provides a nozzle having a fuel injection hole and a concave conical valve seat, a movable iron core at one end, and the movable iron core at the other end. And a plunger rod having a valve element seated on the valve seat,
In the method of manufacturing a fuel injection valve, wherein the valve portion has a convex conical throttle portion on the downstream side thereof, the movable iron core, the valve portion, and the throttle portion are integrally formed of the same material, and the throttle is provided. There is provided a method for manufacturing a fuel injection valve, characterized in that the valve portion is processed by using a convex cone shape of the portion as a center.

Preferably, in order to achieve the above first to fourth objects, in the method for manufacturing a fuel injection valve, the plunger rod has a thrust surface that contacts a stopper that determines a stroke end of the plunger rod, A method for manufacturing a fuel injection valve is provided, in which the valve element portion and the thrust surface are cut from a diagonal side of the plunger rod in the axial direction by a single grindstone and simultaneously subjected to cylindrical grinding.

[0019]

According to the present invention having the above-mentioned structure, the convex conical throttle having the same apex angle as the concave conical shape of the valve seat is provided downstream of the contact portion of the substantially spherical valve element with the valve seat. By providing the portion, the passage formed between the throttle portion and the valve seat has a constant width in the fuel flow direction when the valve is opened, and the fuel flow is stable without turbulence. As a result, stable fuel flow rate characteristics can be obtained.

Further, since the throttle portion is formed so as to be separated from the valve seat with a gap portion when the valve is closed, the substantially spherical valve child portion is seated in line contact with the valve seat, and the sealing property is secured.

Further, the movable iron core, the valve portion and the throttle portion are all integrally formed of the same material, and the convex cone shape of the throttle portion is used as the center to machine the valve portion.
The movable iron core, the valve portion, and the throttle portion are not displaced from each other in the axial center, the coaxiality therebetween is secured, and the sealing property is improved. as a result,
Stable fuel flow rate characteristics can be obtained.

Further, the valve rod portion and the thrust surface are cut from a diagonal side of the plunger rod in the axial direction by a single grindstone and simultaneously subjected to cylindrical grinding, so that the stroke of the plunger rod is always kept constant and the valve opening. Area is stable,
Fuel metering accuracy is improved. As a result, stable fuel flow rate characteristics can be obtained.

[0023]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. First, FIG. 2 is an overall structural diagram of the fuel injection valve of the present embodiment.
Will be described. In FIG. 2, the fuel injection valve of this embodiment includes a nozzle 1 having a fuel injection hole 1a and a concave conical valve seat 1b, and a swirler 2 provided in the nozzle 1 and having a guide hole for swirling the fuel. , A plunger rod 3 having a movable iron core 3a at one end and a substantially spherical valve element 3b for adjusting the fuel injection amount at the other end, a ring 4 coupled to the plunger rod 3, and a plunger rod 3 It is composed of a stopper 5 that determines the stroke end, a core 7 that is a fixed iron core that guides the magnetic force from the electromagnetic coil 6, and a yoke 8 that is a case of these.

The plunger rod 3 is slidable by being guided by the guide hole of the swirler 2, the inner diameter of the core 7 and the ring 4, and is closed by the coil spring 9 when no electromagnetic force is generated. ing. York 8
The fuel press-fitted into the cylinder is swirled by the swirler 2 and a signal is given to the electromagnetic coil 6, whereby an electromagnetic force is generated and the plunger rod 3 is opened to inject fuel from the injection hole of the nozzle 1. .

A detailed cross section of the valve portion 3b is shown in FIG. A convex conical throttle portion 3c is provided on the downstream side of the contact portion of the valve portion 3b with the valve seat 1b. The apex angle of the narrowed portion 3c is equal to the apex angle α of the concave conical valve seat 1b formed in the nozzle 1. Further, the throttle portion 3c is formed so as to be separated from the valve seat 1b with a gap 50 having a constant width H when the valve is closed.

In the fuel injection valve configured as described above, when the plunger rod 3 is urged by the electromagnetic force to open the valve, the width between the throttle portion 3c and the valve seat 1b is constant in the fuel flow direction. Since the passages are formed, the fuel flow is stable without turbulence. As a result, stable fuel flow rate characteristics can be obtained. Further, when the valve is closed, the convex conical throttle portion 3c is separated from the valve seat 1b by the void portion 50 having a constant width H, so that the substantially spherical valve element portion 3b is seated in line contact with the valve seat 1b and is sealed. Sex is secured.

Next, a method of manufacturing the fuel injection valve will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 3 shows the details of the valve portion of the fuel injection valve and the vicinity of the thrust surface. In order to obtain the accuracy of the stroke S of the plunger rod, from the valve element 3b to the stopper 5
It is necessary to secure a distance L to the thrust surface 14 in contact with. Conventionally, the thrust surface 14 is processed by connecting the movable iron core 3a to the valve member 3b which is a separate member, and then detecting the distance L based on the valve member 3b. In the method of manufacturing the fuel injection valve of the present embodiment, the spherical surface machining of the valve element 3b and the grinding of the thrust surface 14 of the plunger rod 3 are simultaneously performed on the fuel injection valve having the valve element 3b having a substantially spherical shape. Thus, the distance L from the valve portion 3b to the thrust surface 14 is maintained with high accuracy, and in addition to this, the movable iron core 3a, the valve portion 3b, and the throttle portion 3c are integrally formed of the same material, and the throttle portion 3c is formed. The movable iron core 3a, the valve portion 3b, and the throttle portion 3c are formed by processing the valve portion 3b by using the convex cone shape of FIG.
It is to ensure the coaxiality with. An apparatus for performing this processing is shown in FIGS. 4 and 5.

In FIG. 4, the plunger rod 3 is supported at both ends by a headstock 15 and a tailstock 16, and is rotated about a line connecting the headstock 15 and the tailstock 16. With respect to the rotating plunger rod 3, a grindstone 18 formed by a grindstone forming device 17 is rotated while being cut by a cutting table 19 from an oblique side in the axial direction of the plunger rod on the thrust surface 14 side to perform cylindrical grinding. . This allows the thrust surface 14 and the substantially spherical valve element 3b to be machined at the same time. Therefore, it is possible to maintain the distance L from the substantially spherical valve element 3b to the thrust surface 14 with high accuracy only by performing grinding wheel formation and correction of the cut amount for accuracy deterioration due to wear of the grinding wheel 18.

FIG. 5 shows details of the vicinity of the concave surface 13 of the tailstock 16. In FIG. 5, the movable iron core 3a
The concave portion 13 of the tailstock 16 receives the throttle portion 3c of the plunger rod 3 in which the valve portion 3b and the throttle portion 3c are integrally made of the same material, and the convex conical shape of the throttle portion 3c is used as the center. Then, the valve portion 3b having a substantially spherical shape is processed. As a result, the axial center does not deviate as when connecting different members, the coaxiality of the movable iron core 3a, the valve portion 3b, and the throttle portion 3c is secured, and the sealing performance is improved.

As described above, according to the fuel injection valve of the present embodiment, the concave cone of the valve seat 1b is located downstream of the contact portion between the substantially spherical valve element 3b and the concave cone valve seat 1b. Since the convex conical throttle portion 3c having the same apex angle α as the shape is provided, the passage formed between the throttle portion 3c and the valve seat 1b has a constant width in the fuel flow direction when the valve is opened, The flow is stable without any turbulence. As a result, stable fuel flow rate characteristics can be obtained. Further, since the throttle portion 3c is formed so as to be separated from the valve seat 1b with the gap 50 having a constant width H when the valve is closed, the valve portion 3b having a substantially spherical shape is formed in the valve seat 1b.
It is possible to secure the sealing property by sitting on b in line contact.

Further, according to the method of manufacturing the fuel injection valve of the present embodiment, the valve portion 3a and the thrust surface 14 are cut with the single grindstone 18 from the lateral side in the axial direction of the plunger rod 3 and simultaneously subjected to the cylindrical grinding. Since the machining is performed, the stroke S of the plunger rod 3 is always kept constant, the opening area of the valve is stabilized, and the fuel metering accuracy is improved. Therefore, stable fuel flow rate characteristics can be obtained. In addition, the movable iron core 3a and the valve portion 3
b and the throttle portion 3c are integrally formed of the same material, and the movable iron core 3a, the valve portion 3b, and the throttle portion are formed by processing the valve portion 3b using the convex conical shape of the throttle portion 3c as a center. There is no deviation of the axial center from 3c, the coaxiality thereof is secured, and the sealing property is improved. As a result, stable fuel flow rate characteristics can be obtained.

In the method of manufacturing the fuel injection valve in this embodiment, the valve seat 1b and the throttle portion 3c have a constant width H as in the fuel injection valve of the first embodiment shown in FIG. The present invention is not limited to the fuel injection valve forming 50, but can be applied as long as the tip of the valve portion has a convex conical shape, and the same effect can be obtained in this case as well.

[0033]

According to the present invention, a convex-cone-shaped throttle portion having the same apex angle as the concave-cone shape of the valve seat is provided on the downstream side of the contact portion of the substantially spherical valve element with the valve seat. Therefore, when the valve is opened, the passage formed between the throttle portion and the valve seat has a constant width in the fuel flow direction, and the fuel flow is stable without turbulence. Therefore, stable fuel flow rate characteristics can be obtained.

Further, since the throttle portion is formed so as to be separated from the valve seat with a gap when the valve is closed, the substantially spherical valve element portion is seated in line contact with the valve seat to ensure the sealing performance. .

Furthermore, since the movable iron core, the valve portion and the throttle portion are all integrally made of the same material and the convex cone shape of the throttle portion is used as the center to process the valve portion, the movable iron core and the valve portion are processed. It is possible to secure the coaxiality of the shaft center of the portion and the throttle portion, improve the sealing performance, and obtain a stable fuel flow rate characteristic.

Further, since the valve element and the thrust surface are cut by a single grindstone from the side oblique to the axial direction of the plunger rod and simultaneously subjected to cylindrical grinding, the opening area of the valve is stabilized and the fuel metering accuracy is improved. Therefore, stable fuel flow rate characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a detailed sectional view of a valve element according to a first embodiment of the present invention.

FIG. 2 is an overall structural diagram of a fuel injection valve.

FIG. 3 is a detailed cross-sectional view near a valve element portion and a thrust surface of the fuel injection valve.

FIG. 4 is a diagram showing an apparatus for carrying out a method for manufacturing a fuel injection valve.

FIG. 5 is a view showing an apparatus for carrying out a method for manufacturing a fuel injection valve.

[Explanation of symbols]

 1 Nozzle 1b Valve seat 3 Plunger rod 3a Movable iron core 3b Valve part 3c Throttling part 5 Stopper 14 Thrust surface 18 Grindstone 50 Gap H H Gap width S Stroke α Conical top angle

Claims (7)

[Claims] 1. A nozzle having a fuel injection hole and a concave conical valve seat, and a plunger rod having a movable iron core at one end and a substantially spherical valve element seated on the valve seat at the other end. In the fuel injection valve, wherein the plunger rod slides by applying an electromagnetic force to the movable iron core to adjust the injection amount from the fuel injection hole, the valve portion is the valve of the valve portion. The downstream side of the contact portion with the seat has a convex conical throttle portion having the same apex angle as the concave cone shape of the valve seat, and the flow of fuel between the throttle portion and the valve seat when the valve is opened. A fuel injection valve, wherein a passage having a constant width is formed in a direction. 2. The fuel injection valve according to claim 1, wherein the throttle portion is formed so as to be separated from the valve seat by a gap portion having a constant width when the valve is closed. 3. The fuel injection valve according to claim 1, wherein the movable iron core, the valve portion, and the throttle portion are all integrally formed of the same material. 4. The method of manufacturing a fuel injection valve according to claim 1, wherein the movable iron core, the valve element portion, and the throttle portion are integrally formed of the same material, and the convex conical shape of the throttle portion is a center. A method of manufacturing a fuel injection valve, characterized in that the valve element is processed as a valve. 5. The method for manufacturing a fuel injection valve according to claim 4, wherein the plunger rod has a thrust surface that comes into contact with a stopper that determines a stroke end of the plunger rod, and the valve element portion and the thrust surface are connected to the plunger. A method for manufacturing a fuel injection valve, comprising cutting with a single grindstone from an oblique side of an axial direction of a rod and simultaneously performing cylindrical grinding. 6. A nozzle having a fuel injection hole and a concave conical valve seat, and a plunger rod having a movable iron core at one end and a valve element seated on the valve seat at the other end, In the method for manufacturing a fuel injection valve, wherein the valve portion has a convex conical throttle portion on the downstream side thereof, the movable iron core, the valve portion, and the throttle portion are integrally formed of the same material, and the throttle is provided. A method for manufacturing a fuel injection valve, characterized in that the valve portion is processed by using a convex cone shape of the portion as a center. 7. The method for manufacturing a fuel injection valve according to claim 6, wherein the plunger rod has a thrust surface that comes into contact with a stopper that determines a stroke end of the plunger rod, and the valve element portion and the thrust surface are connected to the plunger. A method for manufacturing a fuel injection valve, comprising cutting with a single grindstone from an oblique side of an axial direction of a rod and simultaneously performing cylindrical grinding.