WO2022254988A1

WO2022254988A1 - Electromagnetic fuel injection valve

Info

Publication number: WO2022254988A1
Application number: PCT/JP2022/018334
Authority: WO
Inventors: 涼介竹中; 健一吉村; 貴洋小泉; 貴是村瀬; 昌輝森谷
Original assignee: 日立Astemo株式会社
Priority date: 2021-05-31
Filing date: 2022-04-20
Publication date: 2022-12-08
Also published as: JP7449451B2; JPWO2022254988A1; CN117425773A

Abstract

In the present invention, a guide section (50) provided to the inner circumferential surface of a valve housing (2) enables a movable core (12) to always be slidably supported in a smooth manner regardless of whether said movable core (12) is inclined or not. The guide section (50) provided to the inner circumferential surface of the valve housing (2) has an annular shape and includes an inner circumferential surface that is a protruding curved surface (50a) supporting the movable core (12) so as to be slidable and inclinable.

Description

electromagnetic fuel injection valve

The present invention relates to an electromagnetic fuel injection valve that is mainly used in the fuel supply system of an engine.

Conventionally, as an electromagnetic fuel injection valve for an engine, a magnetic cylinder is placed at the rear end of a valve seat member having a valve seat at the front end, a non-magnetic cylinder is placed at the rear end of the magnetic cylinder, and the non-magnetic cylinder is placed at the rear end of the magnetic cylinder. a valve housing in which fixed cores are coaxially coupled to the rear end of a magnetic cylindrical body; a valve body cooperating with the valve seat within the valve housing; a movable core supported by the valve housing so as to be axially slidable while facing the front end face of the fixed core; and a valve spring that biases the movable core and the valve body in the valve closing direction when the coil is de-energized, as described in Patent Document 1 below. Are known.

Japanese Patent Application Laid-Open No. 2003-206820

By the way, in such an electromagnetic fuel injection valve, smoothing the axial sliding of the movable core is an important issue for stabilizing the fuel injection characteristics. In order to solve this problem, in the valve housing disclosed in Patent Document 1, an annular guide portion having a cylindrical inner peripheral surface is protruded from the inner peripheral surface of the valve housing, and this guide portion slides the movable core in the axial direction. It is supported so that it can move (hereinafter simply referred to as “sliding”).

However, it is necessary to provide a sliding gap between the guide portion and the movable core, which may cause the movable core to tilt to some extent. The movable core comes into contact with the edge of the cylindrical inner peripheral surface of the part, that is, the edge part, and the surface pressure of the contact part of both rises excessively, and the fuel oil film intervening in the contact part is cut off. Not only is the smooth sliding of the movable core impaired, but also the wear resistance of the movable core is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and the guide portion provided on the inner peripheral surface of the valve housing supports the movable core in a smooth and slidable manner at all times regardless of whether or not the core is tilted. It is an object of the present invention to provide an electromagnetic fuel injection valve with stable fuel injection characteristics and high durability.

In order to achieve the above object, the present invention provides a magnetic cylinder at the rear end of a valve seat member having a valve seat at the front end, a non-magnetic cylinder at the rear end of the magnetic cylinder, and a non-magnetic cylinder at the rear end of the magnetic cylinder. a valve housing in which fixed cores are coaxially coupled to the rear end of a magnetic cylindrical body; a valve body cooperating with the valve seat within the valve housing; a movable core supported by the valve housing so as to be axially slidable while facing the front end surface of the fixed core; and a valve spring that biases the movable core and the valve body in the valve closing direction of the valve body when the coil is de-energized, wherein the inner periphery of the valve housing A first feature is that the surface is provided with an annular guide portion having a convexly curved inner peripheral surface for supporting the movable core in a slidable and tiltable manner.

In addition to the first feature, the convex curved surface is formed on the inner periphery of a virtual torus having a large circle center on the center line of the valve housing and a small circle center on the outside of the valve housing. A second feature is that it is formed to follow the circular arc surface on the side.

According to the first feature of the present invention, the inner peripheral surface of the guide section is formed as a convex surface so as to support the movable core so as to be slidable and tiltable. Regardless of the presence or absence of the fuel oil film, the curved surfaces are always in contact with each other, and an excessive increase in surface pressure does not occur at the curved surface contact portions of the two, so that the intervening fuel oil film can be maintained. As a result, the movable core can always be smoothly slidably supported by the guide portion, and the wear resistance of the movable core can be maintained. And it can contribute to the improvement of durability.

According to the second feature of the present invention, the convex curved surface of the guide portion is formed on the inner peripheral side of a virtual torus with the center of a large circle on the center line of the valve housing and the center of a small circle on the outside of the valve housing. By following the arc surface of the above, the curvature of the convex curved surface becomes constant, and the curved surface contact state of the movable core and the guide part is always stabilized regardless of the inclination of the movable core, Smoother sliding can be ensured.

1 is a longitudinal sectional view showing an embodiment of an engine electromagnetic fuel injection valve according to the present invention; Enlarged view of 2 arrows in FIG.

An embodiment of the present invention will be described below based on the accompanying drawings. In the electromagnetic fuel injection valve I of the present invention, the fuel injection side is defined as the front, and the fuel inlet side is defined as the rear.

First, in FIG. 1, a cylinder head 40 of an engine E is provided with a mounting hole 41 that opens into a combustion chamber 42. The mounting hole 41 is fitted with an electromagnetic fuel injection valve I that can inject fuel into the combustion chamber 42. is installed. At that time, a cushion member 43 is interposed between the fuel injection valve I and the cylinder head 40 .

The valve housing 2 of the electromagnetic fuel injection valve I includes a cylindrical valve seat member 3, a magnetic cylinder 4 fitted to the outer peripheral surface of the rear end portion of the valve seat member 3 and welded in a liquid-tight manner. A non-magnetic cylinder 6 abuts against the rear end of the magnetic cylinder 4 and welded in a liquid-tight manner. and a fuel inlet cylinder 26 fitted to the outer circumference of the rear end of the fixed core 5 and welded in a liquid-tight manner.

The valve seat member 3 includes a valve hole 7 opening at the front end face, a conical valve seat 8 continuing to the inner peripheral end of the valve hole 7, and a cylindrical guide hole continuing to the large diameter portion of the valve seat 8. 9. A steel plate injector plate 10 having a plurality of fuel injection holes 11 communicating with the valve holes 7 is liquid-tightly welded to the front end face of the valve seat member 3 .

A hollow cylindrical movable core 12 facing the front end face of the fixed core 5 is fitted to the magnetic cylindrical body 4 extending from that portion to the front end of the non-magnetic cylindrical body 6 . A valve body 13 is connected to the movable core 12 .

The valve element 13 includes a spherical valve portion 14 which can slide in the guide hole 9 so as to open and close the valve hole 7 in cooperation with the valve seat 8, and a valve portion 14 connected to the valve portion 14 at its front end. The rear end of the valve rod 15 is press-fitted to the inner peripheral surface of the movable core 12 and welded. Therefore, the valve element 13 can move up and down within the valve housing integrally with the movable core 12 .

The valve rod 15 is made of a pipe material with a slit 15a, the inside of which communicates with the hollow portion of the movable core 12, and the inside and outside of the valve rod 15 communicate through the slit 15a. A plurality of flat surfaces 17 are formed around the spherical valve portion 14 to allow passage of fuel.

The hollow portions of the fuel inlet cylinder 26, the fixed core 5, the retainer 20, the movable core 12 and the valve rod 15, the slit 15a of the valve rod 15, the guide hole 9 of the valve seat member 3, the valve hole 7 and the fuel The injection holes 11 form a series of fuel flow paths 18 within the valve housing 2 .

　In Figs. 1 and 2, a retainer 20 made of a pipe material with a slot is press-fitted and fixed in the middle part of the hollow part of the fixed core 5, and the front end thereof serves as a first spring seat 21. On the other hand, the rear end portion of the valve rod 15 ends in the middle of the hollow portion of the movable core 12, and the upper end portion thereof serves as the second spring seat 22. The spring 23 is compressed, and the set load of the valve spring 23 urges the movable core 12 forward away from the fixed core 5, that is, in the valve closing direction of the valve body 13 . The set load of this valve spring 23 is adjusted by the fitting depth of the retainer 20 to the fixed core 5 .

A ring-shaped stopper member 35 made of a non-magnetic material is embedded in the inner peripheral surface of the movable core 12 and protrudes slightly from the rear end surface.

　In FIG. 1 again, a coil assembly 28 is fitted on the outer periphery of the valve housing 2 corresponding to the fixed core 5 and the movable core 12. As shown in FIG. This coil assembly 28 consists of a synthetic resin bobbin 29 fitted on the outer peripheral surface of the fixed core 5 from the rear end of the magnetic cylinder 4 and a coil 30 wound thereon. A terminal support arm 29a is integrally formed at the rear end of the bobbin 29 to support the base end of the power supply terminal 33 projecting to one side thereof. be done. The coil assembly 28 is covered with a yoke 31 on its substantially half peripheral surface.

A synthetic resin coating layer 27 covering the outer peripheral surface of the magnetic cylinder 4 and the fuel inlet tube 26 and embedding the coil assembly 28 is injection molded. At this time, a coupler 34 that accommodates and holds the power supply terminal 33 and protrudes to one side of the coil assembly 28 is molded integrally with the coating layer 27 .

A fuel filter 36 is attached to the inlet of the fuel inlet tube 26 . A fuel cap 46 is fitted on the outer circumference of the upper end of the fuel inlet tube 26 with a seal member 47 interposed therebetween. This fuel cap 46 is one of a plurality of fuel distribution caps branched from a fuel rail 45 connected to a discharge port of a fuel pump (not shown).

As clearly shown in FIG. 2, an annular guide portion 50 is projected from the inner peripheral surface of the non-magnetic cylindrical body 6 projecting forward from the fixed core 5 . The inner peripheral surface of the guide portion 50 is formed by a convex curved surface 50a, thereby supporting the movable core 12 so as to be slidable and tiltable.

In forming the convex curved surface 50a, the center of a large circle Ob is arranged on the center line Y of the valve housing 2 (which passes through the center of the valve seat 8), and the center of a small circle Os is arranged radially outward of the non-magnetic cylindrical body 6. is set, and the convex curved surface 50a is formed following the arc surface on the inner peripheral side of the virtual torus T. As shown in FIG. The inner peripheral surface of the magnetic cylinder 4 is recessed radially outward from the convex curved surface 50a.

Next, the operation of this embodiment will be described.
When the coil 30 is turned off, the biasing force of the valve spring 23 presses the movable core 12 and the valve body 13 forward, causing the valve portion 14 of the valve body 13 to be seated on the valve seat 8 to close the valve hole 7. . High-pressure fuel pressure-fed from a fuel pump (not shown) to the fuel inlet tube 26 fills a series of fuel passages 18 upstream of the valve hole 7 in the valve housing 2 and waits.

When the coil 30 is energized, the magnetic flux generated by the coil 30 runs through the yoke 31, the magnetic cylinder 4, the movable core 12, and the fixed core 5 in sequence. As soon as the core 12 is attracted to the fixed core 5 against the set load of the valve spring 23, the valve portion 14 of the valve body 13 is separated from the valve seat 8, and the valve hole 7 is opened, the fuel passage 18 is supplied. The high-pressure fuel on standby is directly injected into the combustion chamber 42 of the engine E from the fuel injection hole 11 through the valve hole 7 .

At this time, the stopper member 35 protruding from the rear end surface of the movable core 12 contacts the front end surface of the fixed core 5 to leave a predetermined gap between the opposed end surfaces of the fixed core 5 and the movable core 12, which will be described later. When the coil 30 is turned off, the residual magnetism between the

cores

5 and 12 is reduced, and the valve closing response of the valve element 13 is improved.

When the coil 30 is turned off, the movable core 12 is released from the attraction force from the fixed core 5, so the valve spring 23 separates the movable core 12 from the fixed core 5 with its set load, and the valve body 13 is closed. is closed to stop fuel injection from the fuel injection hole 11 .

In this manner, the movable core 12 that opens and closes the valve body 13 is slidably and tiltably supported by the inner peripheral surface of the guide portion 50 of the non-magnetic cylindrical body 6, that is, the convex surface 50a. The guide portions 50 are in curved surface contact with each other. Therefore, even if the movable core 12 is slightly inclined due to the sliding gap between the movable core 12 and the guide portion 50, the curved surface contact state between the movable core 12 and the guide portion 50 is maintained and the surface of the contact portion is maintained. It is possible to suppress an excessive increase in pressure and prevent breakage of the fuel oil film intervening at the contact portion.

Thus, the guide portion 50 can support the movable core 12 in a smooth sliding and tiltable manner at all times, maintain the wear resistance of the movable core 12, and improve the fuel injection characteristics of the electromagnetic fuel injection valve I. It can contribute to the improvement of stability and durability.

In particular, when the convex curved surface 50a of the guide portion 50 is formed to follow the circular arc surface on the inner peripheral side of the virtual torus T, the curvature of the convex curved surface 50a is kept constant so that even when the movable core 12 is tilted, the movable core 12 can be moved. The state of curved surface contact between the core 12 and the guide portion 50 does not change, and smoother sliding of the movable core 12 can be ensured.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various design changes are possible without departing from the gist of the present invention.

I: Electromagnetic fuel injection valve Ob: Center of large circle Os: Center of small circle T: Virtual torus Y: Center line of valve housing 2: Valve housing 3 Valve seat member 4 Magnetic cylinder 5 Fixed core 6 Non-magnetic cylinder 8 Valve seat 12 Movable core 13 Valve body 30 ... Coil 50 ... Guide portion 50a ... Convex curved surface

Claims

A magnetic cylinder (4) is placed at the rear end of a valve seat member (3) having a valve seat (8) at its front end, and a non-magnetic cylinder (6) is placed at the rear end of the magnetic cylinder (4). , a valve housing (2) in which a fixed core (5) is coaxially coupled to the rear end of the non-magnetic cylindrical body (6), and the valve seat (8) in the valve housing (2). A cooperating valve body (13) is coupled to the rear end of the valve body (13) and is axially slidable in the valve housing (2) while facing the front end face of the fixed core (5). a movable core (12) to be supported; and a coil (30) disposed on the outer periphery of the fixed core (5) and generating an attractive force between the fixed core (5) and the movable core (12) when energized. , a valve spring (23) that biases the movable core (12) and the valve body (13) in the valve closing direction of the valve body (13) when the coil (30) is de-energized. In the injection valve,
An annular guide portion (50) having a convex curved surface (50a) for slidably and tiltably supporting the movable core (12) is provided on the inner peripheral surface of the valve housing (2). An electromagnetic fuel injection valve characterized by:
In the electromagnetic fuel injection valve according to claim 1,
The convex surface (50a) has a large circle center (Ob) on the center line (Y) of the valve housing (2) and a small circle center (Os) outside the valve housing (2). An electromagnetic fuel injection valve characterized in that it is formed along an arcuate surface on the inner peripheral side of a virtual torus (T).