JPH0893958A - Fuel injection valve - Google Patents

Abstract

PURPOSE: To provide a fuel injection valve which can carry out satisfactory spraying characteristics accompanying an increase in fuel flow velocity in a fuel passage by a reduction in internal pressure loss. CONSTITUTION: Since the base end surface 30 of a valve element 1 fitted into and fixed to the fuel hole 7a of a plunger 7 is formed into a protruding surface protruded in the flowing direction of fuel, the fuel flow can be smoothly carried to the peripheral part of the base end surface 30 of the valve element 1 along this base end surface 30, and run from the peripheral part of the base end surface 30 into a chamfered part 13 formed on the outer circumferential surface of the base end part of the valve element 1. Consequently, a satisfactory spraying characteristics accompanying an increase in fuel flow velocity in a fuel passage can be realized by a reduction in internal pressure loss.

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 for supplying fuel to an engine.

[0002]

2. Description of the Related Art A conventional electromagnetically driven fuel injection valve is fixed to a housing by a housing, a linear solenoid having a plunger having a through hole axially extending therethrough, and a guide hole communicating with the injection port. And a valve body which is slidably held by the valve case and whose base end is fitted and fixed in the through hole of the plunger. The outer peripheral surface of the base end of the valve body has a through hole of the plunger. Has a chamfered portion for flowing the fuel in the guide hole.

Further, as shown in FIG. 5, the base end face 30 of the base end of the valve body 1 fitted and fixed in the through hole 7a of the plunger 7 has a corner 105 slightly chamfered.
It is formed flat.

[0004]

In the above-mentioned conventional fuel injection valve, it is required to increase the fuel flow velocity in the fuel passage by reducing the fluid resistance in the fuel passage. However, in the above-described conventional fuel passage configuration, the fuel flow rate flowing through the through hole 104 in the plunger 100 as shown in FIG. 4 becomes a considerable fuel flow rate at the time of high engine output, and as a result, the fuel flow becomes a valve element 102. It was found that the flat base end surface 104 of the base end portion 103 collided with each other and caused a considerable pressure loss.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a fuel injection valve capable of realizing good spray characteristics with an increase in fuel flow velocity in a fuel passage by reducing internal pressure loss. Its purpose is.

[0006]

The first structure of the present invention is as follows.
A housing; a linear solenoid that has a plunger having a through hole formed in the axial direction and is housed in the housing; a valve case that has a guide hole that communicates with an injection port and is fixed to the housing; A valve body that is slidably held in the case and has a base end portion fitted and fixed in the through hole of the plunger, and an outer peripheral surface of the base end portion of the valve body has the through hole of the plunger. In the fuel injection valve having a chamfered portion for flowing the fuel into the guide hole, the base end surface of the valve element is a convex surface.

A second structure of the present invention is characterized in that, in the first structure, the base end surface of the valve body is a conical surface. Here, the conical surface means a tapered rod-shaped body such as a pyramid, a cone, an elliptic cone, or the like. A third structure of the present invention is further characterized in that, in the first structure, the base end surface of the valve body is a chevron surface having a ridge line substantially parallel to the chamfered portion.

[0008]

In the first structure of the present invention,
Since the base end surface of the valve body fitted and fixed in the through hole of the plunger is a convex surface protruding in the fuel flow direction, the fuel flow is
It is possible to smoothly flow along the base end surface to the peripheral edge portion of the base end surface of the valve body, and to flow from the peripheral edge portion of the base end surface to the chamfered portion formed on the outer peripheral surface of the base end portion of the valve body. as a result,
By reducing the internal pressure loss, good spray characteristics can be realized as the fuel flow velocity in the fuel passage increases.

In the second structure of the present invention, since the base end surface of the valve body is a conical surface in the first structure, the flow can be further smoothed. According to a third configuration of the present invention, in the first configuration, the base end surface of the valve body further comprises
As it consists of a chevron with ridges that are almost parallel to the chamfer,
The flow can be further smoothed.

[0010]

1 is a cross-sectional view of an injector (fuel injection valve) according to an embodiment of the present invention, which is an application example of a fuel supply device for a gasoline engine. Injector (fuel injection valve)
A needle (valve body in the present invention) 1 in a cylindrical surface 4a (guide hole in the present invention) of a body (valve case in the present invention) 4 of
Is stored so that it can be moved. When the electromagnetic coil 18 is energized, the needle 1 seated on the valve seat 4b at the bottom of the body 4 is attracted and a gap is created between the needle 1 and the valve seat 4b, and the fuel passes through this gap and the fuel passes through the body. The fuel is injected from a fuel injection hole 21 formed at the bottom of No. 4. The fuel is continuously injected while the electromagnetic coil 18 is energized, and when the energization is completed, the needle 1 is seated on the valve seat 4b again and the fuel injection is completed.

The injector has a substantially cylindrical housing 16 made of a magnetic material above the body 4 in the figure.
A fixed iron core 14, a movable core (plunger in the present invention) 7, a needle 1, a body 4 and the like are disposed in the housing 16 in the axial direction. A resin spool 17 is provided on the inner periphery of the housing 16. Is fixed, and an electromagnetic coil 18 is wound around the spool 17. In addition, the body 4 is inserted inside the medium-diameter portion 83 of the housing 16 via the annular plate-shaped spacer 6, and the guide portions 2 and 3 of the needle 1 slide inside the body 4. A cylindrical surface 4 a and a valve seat 4 b on which the conical seat portion 12 of the needle 1 is seated are formed, and the fuel injection hole 2 is formed in the center of the bottom of the body 4.
1 is formed.

On the other hand, in the small diameter portion 22 of the housing 16,
A movable core (plunger) 7 made of a magnetic material and formed in a tubular shape is slidably provided inside. The upper end surface of the movable core 7 faces the lower end surface of the fixed iron core 14 with a predetermined gap. The upper end of the needle (valve body) 1 is integrally connected to the inner periphery of the lower end of the movable core 7 by laser welding. Further, the upper end surface of the movable core 7 is urged downward in FIG.
A return spring 11 for seating the valve on the valve seat 4b of the body 4 is provided. The return spring 11 projects from the inside of the movable core 7 to the inside of the fixed iron core 14, and is supported by the adjusting pipe 11 which is inserted and fixed inside the fixed iron core 14.

The fixed iron core 14, the electromagnetic coil 18, the return spring 11 and the movable core 7 constitute a linear solenoid 50 in the present invention. Adjusting pipe 11
The biasing force of the return spring 11 is adjusted by adjusting the axial position of the return spring 11. Fixed core 1
A filter 15 that removes dust and the like in the fuel that is pressure-fed from the fuel tank by a fuel pump or the like and flows into the fuel injection valve is provided above 4. The fuel flowing into the fixed iron core 14 flows through the adjusting pipe 11 and the through hole 7a of the movable core 7, and further, the gap between the movable core 7 and the plane relief portion 13 formed in the joint portion 9 of the needle 1, Passes through the gap between the cylindrical surface of the body 4 and the flat relief portions 13 formed in the guide portions 2 and 3 of the needle 1 and reaches the fuel injection hole 21.

A connector 20 made of synthetic resin is provided on the outer periphery of the portion of the fixed iron core 14 that projects from above the spool 17. The terminal 34 electrically connected to the electromagnetic coil 18 is connected to the connector 20.
And is embedded in the spool 17. Also, Terminal 3
4 is connected from an electronic control unit (not shown) via a wire harness, and an exciting current is supplied to the electromagnetic coil 18 via the terminal 34 by the electronic control unit. Then, the needle 1 and the movable core 7 are attracted toward the fixed iron core 14 against the biasing force of the return spring 11. The fuel pressurized to a constant pressure by a fuel pump and a pressure regulator (not shown) flows from the upper portion of the fixed iron core 14 to the filter 15, the adjusting pipe 11, and the movable core 7.
Through the through hole 7a of the needle 1, flows through a gap between the upper conical portion 30 of the needle 1, the movable core 7 and the flat relief portion 13 formed in the joint portion 9, and guides the cylindrical surface 4a of the body 4 and the guide portion of the needle 1. It is supplied to the upstream side of the valve seat 4b through a gap with the plane relief portion formed in 2 and 3. Here, when the electromagnetic coil 18 is energized via the terminal 34 of the connector 20 by an electronic control unit (not shown),
The electromagnetic coil 18 generates an electromagnetic force, and the movable core 7 and the needle 1 connected to the movable core 7 rise up against the biasing force of the return spring 11 until the flange 5 and the spacer 6 collide. As a result, the needle 1 and the movable core 7 are held at this collision position by the electromagnetic force of the electromagnetic coil 18. After that, when the injection control signal is not output to the electromagnetic coil 18 and the electromagnetic force no longer acts, the urging force of the return spring 11 causes the needle 1 to descend and contact the valve seat 4b of the body 4. As a result, the fuel passes through the fuel injection hole 21 from the gap between the seat portion 12 of the needle 1 and the valve seat 4b during the period from the ascent of the needle 1 to the descent of the needle 1 toward the intake valve of the internal combustion engine, Fuel is injected so as not to adhere to the wall surface of the intake manifold (not shown) as much as possible.

The characteristic portion of this embodiment will be described in more detail with reference to FIG. Movable core (plunger in the present invention)
A cylindrical base end portion 1a of a needle (a valve body according to the invention) 1 is fitted and fixed to the downstream end portion of the through hole 7a of the above, and the outer peripheral surface of the base end portion 1a is chamfered by two chamfers. A flat surface relief portion (chamfered portion in the present invention) 13 is formed. Further, the upper end conical portion 30 of the needle 1 forming the base end surface of the base end portion 1a is a substantially conical surface.

The fuel flow in the upper conical portion 30 and the effect of this portion on the fuel flow velocity will be described. The electromagnetic coil 18 is energized, and the electromagnetic force causes the movable core 7 and the needle 1 connected to the movable core 7 to move upward against the biasing force of the return spring 11 until the flange 5 and the spacer 6 collide. , The needle 1 and the movable core 7 are held at this collision position by the electromagnetic force of the electromagnetic coil 18,
While fuel is being injected from the fuel injection hole 21, a flow of fuel is generated inside the injector.

Since the base end surface 30 of the upper end portion (base end portion) 1a of the needle 1 has a conical shape, the flow of the fuel and the inner diameter portion of the movable core 7 and the needle do not change with a sharp angle. 1 and the plane escape portion 13 formed in the core 7 flow into the gap, and the fuel is injected from the fuel injection hole 21.
In this way, by making the upper end shape of the needle 1 into a conical shape, it is possible to eliminate the change in the steep angle of the fuel flow and to suppress the generation of vortices, and as a result, to eject from the fuel injection hole 21. The spray flow rate can be increased, and the spray particle size can be reduced. According to the experiment, the atomized particle size is about 10
I was able to reduce it by%.

In addition, by making the base end portion 1a of the needle 1 which disturbs the fuel flow into a truncated polygonal pyramid shape, the change in the steep angle of the fuel flow is reduced and the flow velocity of the jetted fuel is reduced as in the conical shape. It can also be improved. (Embodiment 2) Another embodiment is shown in FIGS.

In this embodiment, the shape of the upper end portion (proximal end portion) 1a of the needle 1 which disturbs the flow of fuel is directed to the flat relief portion 13 formed by two chamfers on the outer peripheral surface of the proximal end portion 1a. As in the case of the conical shape, the change in the steep angle of the fuel flow is reduced by providing the V-shaped inclination. That is, a ridge line 30b is formed on the base end surface of the base end portion 1a of the needle 1 in parallel with and equidistant from the two chamfered portions 13a, and the ridge line 30b and the upper side of the chamfered portion 13 are flat surfaces (the present invention). Yamagata referred to in 3)
Two sides of 0a and 30b are formed. Of course, the flat surfaces (the chevron surfaces in the present invention) 30a, 30b may be curved, and the clear ridgeline 30b may not be provided.

With this configuration, the fuel can be guided to the chamfered portion 13, so that the fluid resistance can be further reduced.

[Brief description of drawings]

FIG. 1 is an axial sectional view of a fuel injection valve.

FIG. 2 is an axial partial cross-sectional view showing an example shape of a joint portion between a valve body and a plunger of the fuel injection valve of FIG.

3 is an axial partial cross-sectional view showing the shape of another embodiment of the joint between the valve body and the plunger of the fuel injection valve of FIG.

FIG. 4 is a cross-sectional view in the axial direction of the joint portion of FIG.

FIG. 5 is a partial axial sectional view showing the shape of a joint between a valve body and a plunger of a conventional fuel injection valve.

[Explanation of symbols]

1 is a needle 1, 1a is an upper end portion (base end portion) of the needle 1, 4 is a body (valve case), 4a is a cylindrical surface (guide hole), 13 is a flat relief portion (chamfered portion), 16 is a housing, 30 Is a needle upper conical portion (base end surface of the base 1a of the needle 1), 7 is a movable core (plunger), and 50 is a linear solenoid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Kiuchi 1-1-1, Showa-cho, Kariya city, Aichi Prefecture Nihondenso Co., Ltd.

Claims (3)

[Claims] 1. A valve case fixed to the housing having a housing, a linear solenoid having a plunger having a through hole formed in the axial direction and accommodated in the housing, and a guide hole communicating with the injection port. And a valve body that is slidably held in the valve case and has a base end portion that is fitted and fixed in the through hole of the plunger, and an outer peripheral surface of the base end portion of the valve body is of the plunger. A fuel injection valve having a chamfered portion for allowing the fuel in the through hole to flow into the guide hole, wherein the base end surface of the valve element is a convex surface. 2. The fuel injection valve according to claim 1, wherein the base end surface of the valve body is a conical surface. 3. The fuel injection valve according to claim 1, wherein the base end surface of the valve body is a chevron surface having a ridge line substantially parallel to the chamfered portion.