WO2009090794A1

WO2009090794A1 - Fuel injection valve

Info

Publication number: WO2009090794A1
Application number: PCT/JP2008/070916
Authority: WO
Inventors: Hikaru Kikuta; Hiroshi Kawazoe; Yuhei Miura
Original assignee: Aisan Kogyo Kabushiki Kaisha
Priority date: 2008-01-16
Filing date: 2008-11-18
Publication date: 2009-07-23
Also published as: JP2009167901A

Abstract

A fuel injection valve comprises a valve seat member having a fuel injection hole, a magnetic body provided with the valve seat member, a valve element in contact with the valve seat member to close the fuel injection hole, a magnetic armature contained in the body to which armature the valve element is fixed, a magnetic fixed core located opposite to the fuel injection hole with respect to the valve element, a coil provided around the fixed core, and a nonmagnetic member arranged between the body and the fixed core for connecting them liquid tightly. In this type of fuel injection valve, the nonmagnetic member is preferably press fitted in the through hole of the body and the fixed core is press fitted to the inner circumferential surface of the nonmagnetic member. Consequently, the body and the fixed core can be attached through the nonmagnetic member with high precision.

Description

Fuel injection valve

This application claims priority based on Japanese Patent Application No. 2008-6564 filed on Jan. 16, 2008. The entire contents of that application are incorporated herein by reference.
The present invention relates to a fuel injection valve that injects fuel.

JP 2002-81356 describes a fuel injection valve for injecting fuel into a combustion engine (internal combustion engine). The fuel injection valve includes a valve seat member having a fuel injection hole (fuel outlet hole), a magnetic body (valve housing) provided with the valve seat member, and a fuel injection hole in contact with the valve seat member. A closing valve body, a magnetic armature (movable core) housed in the body and fixed to the valve body, and a magnetic fixed core positioned on the side opposite to the fuel injection hole with respect to the valve body; And a coil provided around the fixed core, and a non-magnetic annular nonmagnetic member (spacer) interposed between the body and the fixed core. The non-magnetic member liquid-tightly connects the body and the fixed core.

In the conventional fuel injection valve, the body and the fixed core are abutted against both end surfaces of the nonmagnetic member, respectively, and are welded all around the liquid. According to this structure, when assembling the body and the nonmagnetic member at the time of manufacturing, it is necessary to weld both the body and the nonmagnetic member while keeping both the body and the nonmagnetic member with high accuracy. Further, when assembling the body and the nonmagnetic member, it is necessary to weld both the nonmagnetic member and the fixed core over the entire circumference while accurately holding both the nonmagnetic member and the fixed core. Therefore, the work of assembling the body and the fixed core is troublesome, and it can be said that the assembling accuracy of these parts is likely to fluctuate. That is, the conventional fuel injection valve has a structure in which it is difficult to maintain the manufacturing quality.
The present invention solves the above problems. The present invention provides a fuel injection valve capable of easily and accurately assembling a body and a fixed core via a nonmagnetic member.

The fuel injection valve according to the present invention includes a valve seat member, a body, a valve body, an armature, a fixed core, a coil, and an annular nonmagnetic member. The valve seat member has a fuel injection hole. The body is made of a magnetic material, and has a through-hole through which fuel flows, and a valve seat member is provided in the through-hole. The valve body contacts the valve seat member and closes the fuel injection hole. The armature is made of a magnetic material, is movably accommodated in a through hole of the body, and has a valve body fixed thereto. The fixed core is made of a magnetic material, has a through hole through which fuel flows, and is positioned on the side opposite to the fuel injection hole with respect to the valve body. The coil is provided around the fixed core. The nonmagnetic member is formed of a nonmagnetic material, and is interposed between the body and the fixed core, and liquid-tightly connects the through hole of the body and the through hole of the fixed core. The nonmagnetic member is press-fitted into the through hole of the body, and the fixed core is press-fitted into the inner peripheral surface of the nonmagnetic member.

In this fuel injection valve, the body and the nonmagnetic member can be easily positioned by press-fitting the nonmagnetic member into the through hole of the body. Moreover, the nonmagnetic member and the fixed core can be easily positioned by press-fitting the fixed core into the inner peripheral surface of the nonmagnetic member. The body, the non-magnetic member, and the fixed core are press-fitted into each other, and the body and the fixed core can be liquid-tightly connected via the non-magnetic member, for example, by welding the entire circumference in a state where their relative positions are fixed. .
According to this fuel injection valve, the body and the fixed core can be assembled easily and accurately via the nonmagnetic member.

In the fuel injection valve described above, the body is preferably provided with a support surface that slidably supports the armature. In this case, it is preferable that a clearance (clearance) is provided between the inner peripheral surface of the nonmagnetic member and the armature.
In the fuel injection valve described above, the nonmagnetic member may be slightly deformed when the nonmagnetic member and the fixed core are pressed into the body. Therefore, when the armature is supported by the body and a clearance is provided between the nonmagnetic member and the armature, it is possible to prevent the armature from interfering even when the nonmagnetic member is deformed.

In the above-described fuel injection valve, when one end of the nonmagnetic member has a shear surface formed on the inner peripheral surface thereof and the other end of the nonmagnetic member has a shear surface formed on the outer peripheral surface thereof, It is preferable that one end of the nonmagnetic member on the inner peripheral surface is press-fitted into the through hole of the body, and a fixed core is press-fitted on the other end of the nonmagnetic member having a shear surface on the outer peripheral surface.
The nonmagnetic member can be easily and accurately manufactured by pressing. When an annular nonmagnetic member is manufactured by pressing, a shear surface may be formed on the inner peripheral surface at one end and a shear surface may be formed on the outer peripheral surface at the other end. In this case, if one end of the nonmagnetic member having the shear surface on the inner peripheral surface is press-fitted into the through hole of the body and the fixed core is press-fitted to the other end of the nonmagnetic member having the shear surface on the outer peripheral surface, the shear surface The body, the nonmagnetic member, and the fixed core can be assembled with high accuracy without removing the.

In the fuel injection valve described above, the nonmagnetic member is preferably a cylindrical member having a substantially constant thickness.
In the fuel injection valve described above, the nonmagnetic member is pressed into the body and the fixed core, so that the nonmagnetic member is held from the entire circumferential direction by the body and the fixed core. Therefore, the thickness of the nonmagnetic member can be made relatively thin, and it is not always necessary to provide a reinforcing rib or flange. Therefore, the nonmagnetic member can be a cylindrical member having a substantially constant thickness. In this case, the distance between the fixed core and the coil can be designed to be relatively narrow, and a strong magnetic field can be generated in the fixed core.

According to the present invention, a fuel injection valve capable of easily and accurately assembling the body and the fixed core via a nonmagnetic member is realized, and the fuel injection valve can be manufactured with high manufacturing quality.

Sectional drawing which shows the structure of a fuel injection valve. The figure which shows the principal part of a fuel injection valve. The figure which expands and shows a nonmagnetic ring. The figure explaining the manufacturing method of a nonmagnetic ring. The figure which shows typically the magnetic circuit which a coil generate | occur | produces.

Preferred embodiments of the present invention will be listed.
(Mode 1) The fuel injection valve includes an urging member that urges the armature together with the valve body toward the fuel injection hole.
(Form 2) The armature is formed with a through hole. The through-hole of the armature communicates with the through-hole of the fixed core, and constitutes a fuel flow path through which fuel passes together with the through-hole of the fixed core.
(Mode 3) The non-magnetic member is provided at a position surrounding the opposing ends of the armature and the fixed core from the periphery.

FIG. 1 is a cross-sectional view showing a configuration of a fuel injection valve 10 embodying the present invention. The fuel injection valve 10 is a valve device that injects fuel pumped by a fuel pump or the like into an internal combustion engine. As shown in FIG. 1, the fuel injection valve 10 includes a valve seat member 24, a body 26, a valve body 40, an armature 44, a fixed core 32, a nonmagnetic ring 30, a coil 50, a compression spring 46, and a spring pin 36. Yes.

The valve seat member 24 is made of a metal material. A fuel injection hole 22 is formed in the valve seat member 24. The valve seat member 24 is provided with an orifice plate 20 for adjusting the opening area of the fuel injection hole 22. The valve seat member 24 is formed with a plurality of support portions 24e that slidably support the valve body 40 from its periphery.
The body 26 is made of a magnetic material, and more specifically is made of electromagnetic stainless steel. The body 26 has a generally cylindrical shape, and has a through hole 26a through which fuel passes. A valve seat member 24 is fixed to the through hole 26 a of the body 26. The valve seat member 24 is press-fitted into the through hole 26 a of the body 26. In the through hole 26a of the body 26, an annular support surface 26e that supports the armature 44 so as to be slidable from the periphery thereof is formed.

The valve body 40 has a spherical shape and is made of a metal material. The valve body 40 is accommodated in the through hole 26 a of the body 26. The valve body 40 is slidably supported by the support portion 24 e of the valve seat member 24, and can advance and retreat with respect to the fuel injection hole 22. The valve body 40 is in liquid-tight contact with the valve seat member 24 to close the fuel injection hole 22.
The armature 44 is made of a magnetic material, and more specifically is made of electromagnetic stainless steel. The armature 44 is accommodated in the through hole 26 a of the body 26. The armature 44 is slidably supported by the support surface 26 e of the body 26, and can advance and retreat with respect to the fuel injection hole 22. A valve body 40 is fixed to the armature 44 via a cylindrical connecting portion 42. The armature 44 has a generally cylindrical shape and has a through hole 44a through which fuel passes. The through hole 44 a of the armature 44 is connected to the fuel injection hole 22 through the inner hole 42 a of the connection portion 42 and the side wall hole 42 b of the connection portion 42.

The fixed core 32 is made of a magnetic material, and more specifically is made of electromagnetic stainless steel. The fixed core 32 is located on the side opposite to the fuel injection hole 22 (on the side opposite to the fuel injection hole) with respect to the armature 44. The fixed core 32 has a generally cylindrical shape, and has a through hole 32a through which fuel passes. A fuel pipe (not shown) is connected to the end 32d of the fixed core 32 on the side opposite to the fuel injection hole, and fuel is pumped from a fuel pump (not shown) or the like. In the through hole 32a of the fixed core 32, a filter member 38 for removing foreign matter from the pumped fuel is provided at the end 32d on the side opposite to the fuel injection hole.
The nonmagnetic ring 30 is an annular member made of a nonmagnetic material, and is specifically formed of austenitic stainless steel (for example, SUS304 in Japanese Industrial Standard). The nonmagnetic ring 30 is interposed between the body 26 and the fixed core 32, and fluidly connects the through hole 26 a of the body 26 and the through hole 32 a of the fixed core 32. The nonmagnetic ring 30 is provided at a position surrounding the opposite ends of the armature 44 and the fixed core 32 from the periphery. By interposing the nonmagnetic ring 30 made of a nonmagnetic material between the body 26 and the fixed core 32, a strong magnetic field can be generated between the fixed core 32 and the armature 44 when the coil 50 is excited. it can. Thereby, the suction force generated between the fixed core 32 and the armature 44 is increased, and the armature 44 can operate at high speed. The nonmagnetic ring 30 will be described in more detail later.

The coil 50 is provided so as to go around the fixed core 32. The coil 50 is embedded in a case 48 formed of a resin material. The coil 50 is electrically connected to a plurality of terminal pins 52 in the connector 54. The connector 54 is formed by insert molding together with the case 48. The connector 54 is connected to an external control unit (not shown) via a wire harness (not shown). The coil 50 is energized at a timing at which fuel should be injected by the control unit.
The compression spring 46 is accommodated in the through hole 44 a of the armature 44 and the through hole 32 a of the fixed core 32. One end of the compression spring 46 is in contact with the armature 44, and the other end of the compression spring 46 is in contact with the spring pin 36. The compression spring 46 is in a sufficiently compressed state, and urges the armature 44 together with the valve body 40 toward the fuel injection hole 22.
The spring pin 36 has a cylindrical shape in which a slit extending in the axial direction is formed, and is formed of phosphor bronze. The spring pin 36 is press-fitted into the through hole 32a of the fixed core 32, and is fixed to the fixed core 32 by its own elastic force. The biasing force with which the compression spring 46 biases the armature 44 is adjusted by the position where the spring pin 36 is press-fitted. The through hole 36a of the spring pin 36 becomes a fuel flow path through which fuel passes.

Next, the operation of the fuel injection valve 10 will be described. As described above, the pressurized fuel flows into the fuel injection valve 10 from the one end 32d of the fixed core 32 on the side opposite to the fuel injection hole. As shown by an arrow F in FIG. 1, the inflowed fuel includes a filter member 38, a through hole 36 a of the spring pin 36, a through hole 32 a of the fixed core 32, a through hole 44 a of the armature 44, an inner hole 42 a of the connecting portion 42, and The valve portion including the valve seat member 24 and the valve body 40 is reached through the side wall hole 42b. When the coil 50 is not energized, the valve body 40 is in liquid-tight contact with the valve seat member 24 by the urging force of the compression spring 46. In this case, the fuel injection hole 22 is closed by the valve body 40, and fuel is not injected from the fuel injection hole 22.
On the other hand, when a current is passed through the coil 50 and the coil 50 generates a magnetic field, the fixed core 32 and the armature 44 become magnetized. Accordingly, the fixed core 32 and the armature 44 are attracted to each other, and the armature 44 moves together with the valve body 40 toward the fixed core 32 against the urging force of the compression spring 46. That is, the armature 44 moves together with the valve body 40 to the anti-fuel injection hole side. At this time, the fuel injection hole 22 is opened, and fuel is injected from the fuel injection hole 22.

The overall structure and operation of the fuel injection valve 10 of this embodiment have been described above. Next, a detailed description of the configuration of the nonmagnetic ring 30 will be given.
As shown in FIG. 2, the body 26 and the nonmagnetic ring 30 are coupled to each other by press-fitting one end of the nonmagnetic ring 30 into the end portion 26 b of the through hole 26 a of the body 26. That is, the outer peripheral diameter of the nonmagnetic ring 30 is slightly larger than the inner peripheral diameter at the end portion 26b of the through hole 26a of the body 26, and the nonmagnetic ring 30 is compressed in the radial direction. The end portion 26b of the through hole 26a is fitted (that is, a tight fit state). The nonmagnetic ring 30 and the fixed core 32 are also coupled to each other by press-fitting the fixed core 32 into the inner peripheral surface 30 a of the nonmagnetic ring 30. That is, the inner peripheral diameter of the nonmagnetic ring 30 is slightly smaller than the outer peripheral diameter of the fixed core 32, and the nonmagnetic ring 30 is fitted to the outer peripheral surface 32b of the fixed core 32 in a state of being radially extended. (I.e., a tight fit).
In the present embodiment, the coupling between the body 26 and the nonmagnetic ring 30 and the coupling between the nonmagnetic ring 30 and the fixed core 32 are performed by press-fitting. As a result, the assembly of the body 26 and the fixed core 32 via the nonmagnetic ring 30 can be performed easily and accurately. Here, the outer peripheral surface 30b of the nonmagnetic ring 30 and the end portion 26b of the through hole 26a of the body 26 are welded in a liquid-tight manner over the entire circumference after press-fitting. Further, the inner peripheral surface 30a of the nonmagnetic ring 30 and the outer peripheral surface 32b of the fixed core 32 are also liquid-tightly welded over the entire periphery after press-fitting.
Here, the dimensional difference between the outer peripheral diameter of the nonmagnetic ring 30 and the inner peripheral diameter at the end portion 26b of the through hole 26a of the body 26 into which the nonmagnetic ring 30 is press-fitted is appropriately set according to the dimensions, shape, and material (rigidity). Good. In the structure of the present embodiment, when the outer peripheral diameter of the nonmagnetic ring 30 and the inner peripheral diameter at the end portion 26b of the through hole 26a of the body 26 are about 5 mm to 10 mm, the dimensional difference between the two can be 5 μm to 20 μm. . Similarly, regarding the inner peripheral diameter of the nonmagnetic ring 30 and the outer peripheral diameter of the fixed core 32, when the dimensions are about 5 mm to 10 mm, the dimensional difference between the two can be 5 μm to 20 μm.

2, the armature 44 is supported by a support surface 26e formed on the body 26. A clearance (gap) is provided between the outer peripheral surface 44 b of the armature 44 and the inner peripheral surface 30 a of the nonmagnetic ring 30. In order to secure the clear lath, the inner peripheral diameter D2 of the inner peripheral surface 30a of the nonmagnetic ring 30 is designed to be larger than the inner peripheral diameter D1 of the annular support surface 26e formed on the body 26. According to this structure, even when the nonmagnetic ring 30 is slightly deformed by press fitting or welding during manufacturing as described above, the nonmagnetic ring 30 is prevented from interfering with the armature 44 and the operation of the armature 44 is hindered. There is nothing. Furthermore, according to this structure, the deformation of the nonmagnetic ring 30 can be tolerated to some extent at the time of manufacture, so that the nonmagnetic ring 30 can be made relatively thin and simple. That is, it is not necessary to form reinforcing ribs or flanges on the nonmagnetic ring 30. Therefore, the nonmagnetic ring 30 of the present embodiment is formed in a simple cylindrical shape with a substantially constant thickness (approximately 0.4 mm).

In FIG. 3, the nonmagnetic ring 30 is further enlarged and shown. As shown in FIG. 3, at one end 30c of the nonmagnetic ring 30 press-fitted into the through hole 26a of the body 26, a shear surface 30g is formed on the inner peripheral surface 30a. In addition, at the other end 30d of the nonmagnetic ring 30 into which the fixed core 32 is press-fitted, a shear surface 30h is formed on the outer peripheral surface 30b. Here, the shear surfaces 30g and 30h mean cross sections generated by shearing, and indicate uneven surfaces having a relatively large surface roughness. The reason why the shear surfaces 30 g and 30 h are formed on the nonmagnetic ring 30 is due to the manufacturing method of the nonmagnetic ring 30.
With reference to FIG. 4, the manufacturing method of the nonmagnetic ring 30 is demonstrated. As shown in FIG. 4, the nonmagnetic ring 30 is manufactured from a sheet-like base material 130 by pressing. First, as shown in FIG. 4A, a nonmagnetic ring 30 is formed on a base material 130 using a forming die 101. Although only one set of molds 101 is shown in FIG. 4A, in practice, deep drawing is performed many times by a plurality of sets of molds 101. Next, as shown in FIG. 4B, the first punching die 102 is used to punch out the bottom 31 of the nonmagnetic ring 30 formed on the base material 130. At this time, at one end 30c of the nonmagnetic ring 30, a shear surface 30g is formed on the inner peripheral surface 30a. Next, as shown in FIG. 4C, the nonmagnetic ring 30 is punched from the base material 130 using the second punching die 103. At this time, at the other end 30d of the nonmagnetic ring 30, a shear surface 30h is formed on the outer peripheral surface 30b. The shear surfaces 30g and 30h are not removed by post-processing. The nonmagnetic ring 30 is completed with the shear surfaces 30g and 30h remaining.

As described above, the nonmagnetic ring 30 is efficiently manufactured by pressing, but on the other hand,

shear surfaces

30g and 30h are formed at both ends of the nonmagnetic ring 30. However, according to the manufacturing method described above, one shear surface 30g is formed on the inner peripheral surface 30a, and the other shear surface 30h is formed on the outer peripheral surface 30a. Therefore, as shown in FIG. 3, in the fuel injection valve 10 of this embodiment, one end 30c of the nonmagnetic ring 30 having the shearing surface 30g on the inner peripheral surface 30a is press-fitted into the body 26, and the shearing surface 30h is provided. The fixed core 32 is press-fitted into the other end 30d of the nonmagnetic ring 30 provided on the outer peripheral surface 30b. In press-fitting between the body 26 and the nonmagnetic ring 30, even if the shear surface 30 g is formed on the inner peripheral surface 30 a of the nonmagnetic ring 30, this is not a problem. Further, in the press-fitting between the nonmagnetic ring 30 and the fixed core 32, even if the shear surface 30h is formed on the outer peripheral surface 30b of the nonmagnetic ring 30, this is not a problem. Therefore, according to the structure of the present embodiment, when the nonmagnetic ring 30 is manufactured by pressing, it is not necessary to remove the shear surfaces 30g and 30h formed on the nonmagnetic ring 30. According to the structure of the present embodiment, the nonmagnetic ring 30 used therefor can be efficiently manufactured by pressing.

FIG. 5 schematically shows a magnetic circuit M generated when the coil 50 is energized. The nonmagnetic ring 30 does not have a rib, a flange, or the like (the wall thickness is constant), and is formed relatively thin. Therefore, as shown in FIG. 5, the magnetic circuit M that passes through the body 26, the armature 44, and the fixed core 32 is formed at a position relatively close to the coil 50. That is, a magnetic field having a high magnetic flux density can be generated between the armature 44 and the fixed core 32. Therefore, according to the structure of the present embodiment, the armature 44 can be operated at high speed, and the fuel injection amount can be finely adjusted.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, in the above-described embodiment, the support surface 26e that slidably supports the armature 44 is provided on the body 26, but another support surface that slidably supports the armature 44 is provided on the nonmagnetic ring 30. You can also. However, if the support surface is provided on the nonmagnetic ring 30, the shape of the nonmagnetic ring 30 tends to be complicated as compared with the above-described embodiment. On the other hand, since it is not always necessary to provide the support surface 26e on the body 26, the shape of the body 26 can be simplified.

The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Claims

A valve seat member having a fuel injection hole;
A body that is formed of a magnetic material, has a through-hole through which fuel flows, and in which the valve seat member is provided;
A valve body that contacts the valve seat member and closes the fuel injection hole;
An armature formed of a magnetic material, movably accommodated in the through hole of the body, and to which the valve body is fixed;
A fixed core that is formed of a magnetic material, has a through-hole through which fuel flows, and is located on the side opposite to the fuel injection hole with respect to the valve body;
A coil provided around the fixed core;
An annular nonmagnetic member formed of a nonmagnetic material, interposed between the body and the fixed core, and liquid-tightly connecting the through hole of the body and the through hole of the fixed core. Prepared,
The fuel injection valve, wherein the nonmagnetic member is press-fitted into a through hole of the body, and the fixed core is press-fitted into an inner peripheral surface of the nonmagnetic member.
The body is provided with a support surface that slidably supports the armature,
The fuel injection valve according to claim 1, wherein a gap is provided between an inner peripheral surface of the nonmagnetic member and the armature.
At one end of the nonmagnetic member, a shear surface is formed on the inner peripheral surface thereof, and at the other end of the nonmagnetic member, a shear surface is formed on the outer peripheral surface thereof,
One end of the non-magnetic member having a shear surface on the inner peripheral surface is press-fitted into the through hole of the body, and the fixed core is press-fitted to the other end of the non-magnetic member having a shear surface on the outer peripheral surface. The fuel injection valve according to claim 1 or 2.
The fuel injection valve according to any one of claims 1 to 3, wherein the nonmagnetic member is a cylindrical member having a substantially constant thickness.