JP3309209B2 - Air assist type electromagnetic fuel injection valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air assist type electromagnetic fuel injection valve used for a fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art Generally, an electromagnetic fuel injection valve used in an internal combustion engine has a needle (valve element) housed in a guide hole formed in a valve body in an axial direction so as to be reciprocally slidable, and is urged by an electromagnetic force. The opening of the distal end of the valve body is opened and closed by the vertical movement of the needle. JP-A-9-14079 will be described with reference to FIG.

In this publication, an air assist sleeve 63 is provided so as to surround the valve body 26, and the fuel spray injected from the valve body 26 is blown out through the air introduction passages 73 and 74 of the air assist sleeve 63. An air-assisted electromagnetic fuel injection valve has been proposed in which the air is collided with the air to atomize the fuel. The air assist sleeve 63 is accommodated in a pocket portion in an intake manifold (not shown), and air introduction passages 73 and 74 are provided with air passages (not shown) communicating with the respective cylinders (for example, a throttle valve upstream side). ) Is introduced through this pocket.

[0004] The electromagnetic drive structure of the conventional air assist type electromagnetic fuel injection valve shown in FIG. 4 will be briefly described. In order to form a stationary magnetic circuit surrounding the drive coil 32 wound around the resin spool 91, the stationary core 2 which is a highly magnetically permeable member is formed.
1. A magnetic pipe (metal inner cylindrical member) 23, metal pieces (metal outer frame members) 93 and 94 are provided, and a non-magnetic pipe 24 is interposed in an axial gap between the fixed iron core 21 and the magnetic pipe 23. To form a gap in the magnetic circuit.

[0005] A movable iron core (movable body) 22 having a high magnetic permeability is slidably held on the inner peripheral surfaces of the magnetic pipe 23 and the non-magnetic pipe 24. The needle 25 is displaced upward by moving upward to eliminate the gap, and the fuel is sprayed. When the energization is completed, the return spring urges the movable body 22 and the needle 25 downward, and the fuel spray is stopped.

Reference numeral 11 denotes a housing mold (resin outer jacket member) which surrounds and accommodates a solenoid (electromagnetic drive unit) and has a connector 11a with a terminal 34 for energizing the drive coil 32. , Formed by insert molding. 70, 71 are the above-mentioned inte
An insulator or an O-ring for hermetically sealing the pocket portion of the manifold.

[0007]

However, it has been found that the following problems occur in the air-assist type electromagnetic fuel injection valve disclosed in the above-mentioned application filed by the present applicant. More specifically, the housing mold 11 and the metal pieces 93 and 94
For example, if a gap is generated due to thermal strain, airtightness is impaired, and the assist air passage 2 serving as the pocket portion is lost.
Leakage of air from the atmosphere to e causes an increase in the flow rate of air used for fuel spraying, which may affect emission or engine rotation stability.

To solve this problem, a magnetic pipe 2
A step surface (outer peripheral step surface) is formed on the outer periphery of 3 and the tip of the housing mold 11 is extended until it comes into close contact with the outer peripheral step surface of the magnetic pipe 23 so that the housing mold 11 and the metal pieces 93 and 94 are joined together. It is also conceivable to prevent air leakage due to the gap between the two. However, in this case, the outer peripheral step surface of the magnetic pipe 23 which is a metal member and the housing mold 1
If, for example, a gap is formed at a portion where the front end of the first member abuts with the front end due to thermal strain, the same problem as described above occurs.

In order to further solve this problem, an elastic seal member such as an O-ring may be provided between the tip of the housing mold 11 and the outer peripheral step surface of the magnetic pipe 23. However, the housing mold 11 having the various components of the solenoid, the drive coil 32 insulated and sealed, and the terminal 11a, that is, the resin jacket, must be formed by insert molding. It is extremely difficult to accurately hold such an elastic seal member at a predetermined position in a mold while applying an appropriate compressive force, and to avoid adverse thermal effects on the elastic seal member. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can avoid disturbance of combustion characteristics of an engine due to leakage between a resin jacket member and a stationary magnetic circuit component member in contact with the resin jacket member. An object of the present invention is to provide an air-assisted electromagnetic fuel injection valve.

[0011]

According to the first aspect of the present invention, a stationary magnetic circuit of an electromagnetic valve (solenoid valve) for driving a needle, which is a valve body, comprises a needle and a movable body for biasing the needle. A metal inner cylinder member (inner yoke member) having a (movable core) and inserted inside the drive coil, and a metal outer frame member (outer yoke member) mounted outside the drive coil, Furthermore, a resin jacket (cylindrical housing) that covers the outer peripheral surface of the metal outer frame member over the entire circumference, and an air assist sleeve whose base end is attached to and supported by the metal inner cylinder member are provided. The air introduced into the air assist sleeve from the air introduction passage of the assist sleeve converts air (secondary air) into fuel spray injected from a gap between the valve body and the needle in the air assist sleeve. Collision to improve its combustion characteristics .

In this configuration, the following structure is particularly adopted. First, the tip of the resin jacket member was brought into close contact with the outer peripheral step surface of the metal inner cylinder member. With this configuration, since the resin jacket covers the entire metal outer frame member, even if a gap is formed between the metal outer frame member and the resin outer member, the distal end of the resin jacket member and the metal inner cylinder are formed. The leakable portion can be limited to one contact portion with the outer peripheral step surface of the member.

The air assist sleeve not only covers the distal end of the metal inner cylindrical member as in the conventional case, but also
A first gap between the inner peripheral surface of the air-assisted sleeve and the outer peripheral surface of the resin outer cover member is sealed with a gasket to cover the outer peripheral step surface and surround the distal end portion of the resin outer cover member. The gasket also seals the second gap between the inner peripheral surface of the sleeve and the outer peripheral surface of the metal inner cylindrical member at the same time, and furthermore, the gasket covers and seals the entire outer peripheral edge of the outer step surface. Even if a gap is formed between the outer peripheral step surface of the metal inner cylinder member and the tip of the resin jacket member, the air of the air-assisted sleeve passes through the first gap or the second gap from this gap. Air leakage to the introduction passage can be favorably prevented.

Further, the elastic seal member (hereinafter, also referred to as a gasket) is compressed in the radial direction by, for example, an air assist sleeve made of a resin molded part, so that the sealing performance by the gasket can be further improved. Furthermore, this configuration does not require any additional parts or complicated complicated steps other than adding a gasket which is an extremely inexpensive part, and the shape change itself of the resin jacket member and the air assist sleeve is easy, so that It has the advantage of being practical.

According to the second aspect of the present invention, the following configuration is further employed in the first aspect of the invention. (A) The metal inner cylinder member is provided with a ring-shaped groove located at the distal end side of the outer peripheral step surface and into which the distal end of the gasket is fitted. (B) The inner peripheral surface of the air-assist sleeve in contact with the gasket has a two-stage structure of a large-diameter hole portion on the opening side and a small-diameter hole portion on the back side, and the metal small-diameter hole portion on the back side has a metal inner cylindrical member. The tip of the gasket fitted into the annular groove is compressed radially inward, and the gasket that covers the resin jacket member at the large-diameter hole on the opening side is compressed radially inward.

According to this structure, when the metal inner cylindrical member is press-fitted into the air assist sleeve, the small-diameter hole portion acts to push the tip of the gasket into the annular groove portion.
At the time of the press-fitting, the gaskets are not displaced with each other, so that their axial positions do not vary.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples. (Embodiment 1) An air assist type electromagnetic fuel injection valve of this embodiment applied to a fuel supply device for a gasoline engine will be described with reference to FIG.

The air-assist type electromagnetic fuel injection valve is mainly housed in an upper electromagnetic drive section surrounded by a housing mold (resin jacket) 11 and mainly in an air-assist sleeve 63. And a lower injection valve unit driven by the electromagnetic drive unit. (Basic Structure of Electromagnetic Driving Unit) A drive coil 3 wound around a spool 91 made of resin is provided in a housing mold 11 having a cylindrical shape with open both ends formed by insert resin molding.
2, a magnetic circuit is formed.

The magnetic circuit includes a cylindrical fixed iron core 21 having a lower part inserted into a resin spool 91, and metal pieces (metal outer frame members) 93, 9 arranged on the outer peripheral side of the drive coil 32.
4. A magnetic pipe (metal inner cylindrical member) 23 having an upper portion inserted into the resin spool 91, and an axial gap between a lower end of the fixed iron core 21 and an upper end of the magnetic pipe 23 for forming a magnetic gap. A member other than the non-magnetic pipe 24 includes a non-magnetic pipe 24 interposed therebetween, and a movable core (movable body) 22 slidably held on the inner peripheral surfaces of the magnetic pipe 23 and the non-magnetic pipe 24. Has high magnetic permeability. Movable iron core 22
Is biased downward by a return spring 28, that is, in a direction to increase the magnetic gap. The base end of the return spring 28 is supported by an adjusting pipe 29 pressed into the inner peripheral surface of the fixed iron core 21. Have been. A coil mold resin is filled between the metal pieces 93 and 94 and the drive coil 32 for insulation and fixing.

A terminal 34 encloses and accommodates the solenoid and energizes the drive coil 32.
This is a housing mold (resin jacket member) having a connector 11a provided therein, and is formed by insert molding. (Basic Structure of Injection Valve Portion) A needle 25 joined to the lower end of the movable iron core 22 is housed in the magnetic pipe 23 so as to be movable up and down. Valve body to be opened and closed (valve body) 2
6 is press-fitted, a resin-made air assist sleeve 63 surrounds the valve body 26, and the lower end of the magnetic pipe 23 is press-fitted into the air assist sleeve 63. 6
Reference numerals 7 and 68 denote injection holes provided at the lower end of the air assist sleeve 63. Reference numerals 73 and 74 denote injection holes 67 and 68 and the valve body 2 respectively.
6 is an air introduction passage which passes through the peripheral wall of the air assist sleeve 63 in the radial direction.

Reference numeral 2 denotes an intake manifold having a pocket portion 2e forming an air assist passage, and a lower portion of the air assist type electromagnetic fuel injection valve hangs from the upper end opening of the pocket portion 2e into the inside of the pocket portion 2e. . Pocket part 2
At the bottom of e, a hole 2c communicating with the internal space of the intake manifold 2 is provided, and the injection holes 67 and 68 open obliquely downward in the hole 2c.

Reference numeral 70 denotes an opening at the upper end of the intake manifold 2 and the housing mold 1 for airtightness of the pocket 2e.
Numeral 75 designates an insulator made of an elastic material interposed between the outer peripheral surface of the lower end portion 1 and the lower end of the air assist sleeve 63 and the hole 2c of the intake manifold 2 for airtightness of the pocket portion 2e. An O-ring is interposed between the outer peripheral surface of the throttle valve and an air introduction passage 2a that communicates the intake passage upstream of the throttle valve with the pocket 2e.

(Explanation of Operation) When the drive coil 32 is energized, the movable iron core 22 moves upward to eliminate the magnetic gap, the needle 25 is displaced upward, and fuel is sprayed. When the energization is completed, the return spring 28 urges the movable body 22 and the needle 25 downward, and the fuel spray is stopped.

The air flow blown out from the pocket portion 2e through the air introduction passages 73 and 74 of the air assist sleeve 63 and colliding with the fuel spray improves the combustion characteristics of the cylinder.
(Characteristic Configuration of this Embodiment) The characteristics of this embodiment will be described below with reference to FIG. 2 which is an enlarged sectional view of a main part of FIG.

The structure of the present embodiment having the following features is a gap between the housing mold 11 and the metal pieces 93 and 94,
In order to prevent air from leaking from the outside air into the pocket portion 2e through the gaps inside the metal pieces 93 and 94, the flow rate of the air flow colliding with the fuel spray is changed, and the combustion characteristics of the cylinder are not disturbed. The following means are adopted.

(A) The driving coil 3 in the static magnetic circuit
Metal piece (metal outer frame member) 9 which is the outer yoke member of 2
A magnetic pipe which covers the outer peripheral surfaces of the housing molds 3 and 94 over the entire circumference with a housing mold (resin jacket member) 11 and which is positioned by abutting the tips of the metal pieces 93 and 94 on the tips of the housing mold 11. 23 was closely contacted with the outer peripheral step surface 23a.

By doing so, the housing mold 1
1 covers the metal pieces 93 and 94 entirely, so that even if a gap is formed between the metal pieces 93 and 94 and the housing mold 11 due to heat history or the like, the tip of the housing mold 11 is The leakable portion can be limited only to the contact portion with the outer peripheral step surface 23a of the magnetic pipe 23.

(B) The air assist sleeve 63 not only covers the front end of the magnetic pipe 23 but also covers the outer step surface 23a and surrounds the front end of the housing mold 11 to form an air assist sleeve. A first gap between the inner peripheral surface of the sleeve 63 and the outer peripheral surface of the tip of the housing mold 11 was sealed with a gasket 80. Further, the second gap between the inner peripheral surface of the air assist sleeve 63 and the outer peripheral surface of the magnetic pipe 23 is simultaneously sealed by the gasket 80, and the gasket 80 covers the entire outer peripheral edge of the outer step surface 23a. Covered and sealed. The gasket 80 is made of an elastic member such as rubber.

By doing so, the magnetic pipe 2
Even if a gap is formed between the outer peripheral step surface 23a of FIG. 3 and the tip of the housing mold 11, the air-assisted sleeve is passed through the first gap or the second gap from this gap and further through the pocket 2e. 63 air introduction passages 73;
The air leakage to 74 can be prevented well. (C) The air assist sleeve 63 is made of resin, and the magnetic pipe 23 is press-fitted therein. At this press-fit, the air assist sleeve 63 compresses the gasket 80 in the radial direction. Sealability is further improved.

(D) The housing mold 11 has a connector 11a for supplying power to the drive coil 32, and is formed by insert molding. In this way, the adhesion between the metal pieces 93 and 94 and the housing mold 11 can be improved by a simple manufacturing method without deteriorating the sealing performance of the gasket 80.

That is, the gasket 80 may be mounted after integral molding of the housing mold 11 and the metal pieces 93 and 94 by insert molding. Therefore, it is not necessary to insert the gasket 80 into the insert molding die, so that the thermal influence on the gasket 80 can be avoided, and the compressive stress for sealing the gasket 80 does not vary by the insert molding process.

(E) The outer peripheral step surface 23a is formed on the magnetic pipe 23.
An annular groove 23b is provided at a more distal end side and into which the distal end portion 80a of the gasket 80 is fitted. The inner peripheral surface of the air assist sleeve 63 in contact with the gasket 80 has a two-stage structure of a large-diameter hole 63a on the opening side and a small-diameter hole 63b on the rear side. Tip 80a of gasket 80 fitted in annular groove 23b of magnetic pipe 23
Of the gasket 80 that covers the housing mold 11 with the large-diameter hole 63a on the opening side.
b is compressed in the radial direction.

With this arrangement, when the magnetic pipe 23 is press-fitted into the air assist sleeve 63, the small-diameter hole 63b presses the tip of the gasket 80 into the annular groove 23b. The positions of the members 80 in the axial direction are not displaced. According to the air-assisted electromagnetic fuel injection valve of the present embodiment described above, the seal is completed using the air-assisted sleeve 63, which is an existing part, so that the gasket 80, which is an extremely inexpensive part, is added. It does not require any additional parts or complicated and complicated steps, and the shape change of the housing mold 11 and the air assist sleeve 63 is easy, so that the present invention is highly practical. (Embodiment 2) Another embodiment will be described with reference to FIG.

In this embodiment, in the air-assist type electromagnetic fuel injection valve of the first embodiment, the gasket 80 is pressed in the axial direction by the outer peripheral step surface 11b of the housing mold 11 and the upper end of the air-assist sleeve 63. Further, a configuration is further adopted in which the gasket 80 is pressed in the axial direction by the inner peripheral stepped surface 63c provided at the innermost surface of the air assist sleeve 63 and the annular groove 23a of the magnetic pipe 23.

In this way, the sealing performance can be further improved.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of an air-assisted electromagnetic fuel injection valve according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged sectional view of a main part of an air-assist type electromagnetic fuel injection valve according to Embodiment 2 of the present invention.

FIG. 4 is an axial sectional view of a conventional air-assisted electromagnetic fuel injection valve.

[Explanation of symbols]

22 is a movable iron core (movable body), 25 is a needle, 23 is a magnetic pipe (metal inner cylinder member), 32 is a drive coil, 93,
94 is a metal piece (metal outer frame member), 11 is a housing model.
, A valve body, 23a is an outer step surface, 73 and 74 are air introduction passages, 63 is an air assist sleeve, 67 and 68 are injection holes, 80 is a gasket (elastic sealing member), 11a is a connector, 23b is an annular groove,
63a is a large diameter hole, 63b is a small diameter hole.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-100762 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 51/08 F02M 51/06 F02M 69 / 04

Claims (2)

(57) [Claims] 1. A highly magnetically permeable movable body and a needle urged by the movable body are accommodated in an axially displaceable manner and constitute a part of a stationary magnetic circuit for driving the movable body. And a metal inner cylinder member, which is disposed outside the metal inner cylinder member with a drive coil for operating the magnetic circuit interposed therebetween and forms another part of the stationary magnetic circuit, and a tip end portion of the metal inner cylinder member A high-permeability metal outer frame member that is in contact with the outer peripheral surface of the metal outer frame member over the entire circumference, and a resin outer jacket member whose tip is in close contact with the outer peripheral step surface of the metal inner cylindrical member; A valve body that opens and closes an opening, a portion of the metal inner cylinder member that is closer to the distal end than the outer peripheral step surface, and a distal end portion of the resin jacket member are enclosed at a base end side, and fuel spray is injected from the valve body. Air introduction passage for blowing air to collide with An air-assisted electromagnetic fuel injection valve having an injection hole at the tip end side for blowing out fuel spray with the air colliding. An air-assisted electromagnetic fuel injection valve comprising: The base end is compressed radially inward by the air assist sleeve to seal between the inner peripheral surface of the air assist sleeve and the outer peripheral surface of the resin jacket member. An elastic seal member for compressing a portion of the air-assisted sleeve in a radially inward direction to seal between an inner peripheral surface of the air-assisted sleeve and an outer peripheral surface of the metal inner cylindrical member. Features an air-assisted electromagnetic fuel injection valve. 2. The air-assisted electromagnetic fuel injection valve according to claim 1, wherein the metal inner cylindrical member has a ring-shaped groove recessed forward from the outer peripheral step surface, and a distal end of the elastic seal member. The part is fitted in the annular groove part,
The proximal end of the elastic seal member is extended from the distal end to surround the distal end of the resin sheathing member, and the air assist sleeve has a diameter extending from the proximal end of the elastic seal member. A large-diameter hole surrounding the distal end of the resin jacket member while compressing inward, and forming the metal while compressing the distal end of the elastic seal member radially inward to be smaller than the large-diameter hole. An air-assisted electromagnetic fuel injection valve having a small-diameter hole surrounding the inner cylinder member, wherein the metal inner cylinder member is press-fitted into the air-assist sleeve.