JP2000145589A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fuel injection characteristic and fuel sealing performance of fuel injection valves, facilitate their manufacture and reduce their manufacturing man-hour and cost. SOLUTION: A nozzle plate 61 has a smaller thickness at its cylinder portion 61b than at its bottom portion 61a, so that the cylinder portion 61b of reduced rigidity fitted on a valve body 26 prevents excessive compressive stresses on it irrespective of the inside diameter of nozzle holes 61d and keeps that internal wall of the valve body 26 which forms fuel passages 27a and 27b free of significant dimensional changes. This further keeps a guide portion 26a where a valve element 25a slides and a valve seat portion 26b where it is seated free of dimensional changes to thus improve the sliding motion of the valve element 25a or improve the fuel injection characteristic and the fuel sealing performance while the valve element 25a is inactivated. The dimensional design is easily obtainable from a single punching/drawing process of a uniform-thickness plate or from such a punching/drawing process plus succeeding drawing.

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, and more particularly to a structure of an injection hole member having an injection hole.

[0002]

2. Description of the Related Art For example, in a fuel injection valve for injecting and supplying fuel to an internal combustion engine for an automobile (hereinafter, referred to as an engine), a fuel consumption is reduced, an exhaust emission is improved, and a stable engine is provided. From the viewpoint of drivability, etc.
“Atomization of fuel” injected from the injection hole is one of the important factors. As a method of promoting the atomization of the injected fuel (spray), there are auxiliary atomizing means by collision of air with the spray, heating near the injection hole, etc., but all these atomizing means are expensive. There is a problem that becomes.

[0003] Therefore, an injection hole member having a plate-like plate portion is disposed on the fuel downstream side of a valve body having a valve seat, and an injection hole adapted to atomize spray is provided in this plate portion. Injection valves are known. The above-mentioned injection hole member is generally formed by processing a metal plate with a uniform thickness into a bottomed cylindrical shape with a uniform thickness to form an injection hole at the bottom. Are joined by

[0004]

In such a fuel injection valve, the thickness of the bottom of the injection hole member is selected so as to have a fixed ratio with the diameter of the injection hole within a predetermined range. Therefore, in a fuel injection valve of a type in which the fuel injection amount is relatively large, that is, the injection hole diameter is relatively large, it is necessary to make the thickness of the bottom of the injection hole member relatively large.

However, in a conventional fuel injection valve using an injection hole member formed in a bottomed cylindrical shape having a uniform plate thickness, if the bottom thickness of the injection hole member is set to be large, the injection hole diameter is relatively small. The thickness of the side portion of the injection hole member is larger than that of the fuel injection valve. For this reason, in a fuel injection valve of a type having a relatively large injection hole diameter, the rigidity of the side portion of the injection hole member increases, and when the side portion is press-fitted into the valve body, excessive compression stress may be generated in the valve body. There is. When excessive compressive stress is generated in the valve body, the dimensions of the inner wall of the valve body forming the fuel passage, that is, the guide portion on which the valve member slides and the valve seat portion with which the valve member abuts change, and the sliding of the valve member changes. However, there has been a problem that the fuel injection characteristics deteriorate and the fuel injection characteristics deteriorate, and the fuel sealing performance when the valve member is not operated deteriorates, thereby adversely affecting the basic characteristics of the fuel injection valve.

In order to prevent excessive compressive stress from being generated in the valve body when the side portion of the injection hole member is pressed into the valve body, it is conceivable to reduce the press-fit amount of the side portion. However, it is difficult to determine the press-fit amount of the side portion so that excessive compressive stress does not occur in the valve body, and to manage the accuracy of the press-fit amount so as to fall within the tolerance of the determined press-fit amount. . Therefore, there is a problem that manufacturing is difficult and manufacturing man-hours and manufacturing costs increase.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel injection valve having improved fuel injection characteristics and fuel sealability. Another object of the present invention is to provide a fuel injection valve which is easy to manufacture and reduces the number of manufacturing steps and manufacturing cost.

[0008]

According to the fuel injection valve of the first aspect of the present invention, the injection hole member has a side portion to be press-fitted into the valve body, an opening formed in the valve body, and the outside. It has a bottom part having an injection hole for communication, and a stress reducing means for suppressing a dimensional change of an inner wall of a valve body forming a fuel passage at the time of press-fitting the side part. For this reason, when the side portion is press-fitted into the valve body, it is possible to prevent excessive compressive stress from being generated in the valve body regardless of the diameter of the injection hole, and to suppress a dimensional change in the inner wall of the valve body forming the fuel passage. . Therefore, it is possible to suppress a change in the dimensions of the guide portion on which the valve member slides and the valve seat portion with which the valve member abuts, improve the sliding of the valve member, improve the fuel injection characteristics, and operate the valve member when it is not operating. In this case, the sealing performance of the fuel can be improved.

According to the fuel injection valve of the second aspect of the present invention, since the thickness of the side portion of the injection hole member is smaller than the thickness of the bottom portion, the rigidity of the side portion is more reliable than that of the injection hole member having a uniform plate thickness. To decline. For this reason, when the side portion is pressed into the valve body, it is possible to reliably prevent the occurrence of excessive compressive stress in the valve body regardless of the diameter of the injection hole, and to easily change the dimensional change of the inner wall of the valve body forming the fuel passage. And it can be suppressed reliably. Therefore, it is possible to reliably suppress a change in the dimensions of the guide portion on which the valve member slides and the valve seat portion with which the valve member abuts, improve the sliding of the valve member, and reliably improve the fuel injection characteristics. , The sealing performance of the fuel can be improved without fail.

Further, making the thickness of the side portion of the injection hole member smaller than the thickness of the bottom portion can be achieved by, for example, only pressing and drawing a flat plate having a uniform thickness, or by adding a drawing step after the pressing and drawing. It can be done easily. Therefore, manufacturing is easy, and the number of manufacturing steps and manufacturing cost can be reduced.

According to the fuel injection valve of the third aspect of the present invention, the thickness of the corner between the side and the bottom of the injection hole member is smaller than the thickness of the side and the bottom. The rigidity of the corner portion is reliably reduced as compared with the hole member. For this reason, when the side portion is press-fitted into the valve body, it is possible to reliably prevent excessive compressive stress from being generated in the valve body regardless of the diameter of the injection hole, and to surely prevent the dimensional change of the inner wall of the valve body forming the fuel passage. Can be suppressed. Therefore, it is possible to easily and reliably suppress a change in the dimensions of the guide portion on which the valve member slides and the valve seat portion with which the valve member abuts, and improve the fuel injection characteristics by improving the sliding of the valve member. In addition, the sealing performance of the fuel when the valve member is not operated can be reliably improved.

Further, making the thickness of the corner portion of the injection hole member smaller than the thickness of the side portion and the bottom portion is, for example, to add a drawing step after press-drawing and drawing a flat plate having a uniform thickness. This can be easily performed by deleting a part of the section. Therefore, manufacturing is easy, and the number of manufacturing steps and manufacturing cost can be reduced.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; 1 and 2 show a first embodiment in which the present invention is applied to a fuel injection valve of a fuel supply device for a gasoline engine.

As shown in FIG. 2, a fixed iron core 21, a spool 51, an electromagnetic coil 32, metal plates 53 and 54 are provided inside a resin casing 11 of the fuel injection valve 10.
The pressurized fuel is introduced into the fixed iron core 21 from above as shown in FIG.

The fixed iron core 21 made of a ferromagnetic material has a fuel passage 21a therein, and is configured such that pressurized fuel can flow through the fuel passage 21a. Also, the fuel passage 2
An adjusting pipe 29 having a fuel passage (not shown) that can communicate with the fuel passage 21a is accommodated in 1a, and is configured to be fixed in the fixed iron core 21 by press-fitting means or the like and to be movable in the axial direction. .

A non-magnetic pipe 2 is provided between the fixed iron core 21 and the magnetic pipe 23 located on the non-fuel introduction side of the fixed iron core 21.
4 are located. The fixed iron core 21, the non-magnetic pipe 24, and the magnetic pipe 23 are joined to each other by laser welding.

On the anti-fuel introduction side of the adjusting pipe 29, the needle 25 is connected to the anti-adjusting pipe 29.
A compression coil spring 28 biasing to the side is located, and this compression coil spring 28 is housed in the fixed iron core 21. The compression coil spring 2 is moved by the axial movement of the adjusting pipe 29 described above.
The urging force on the needle 25 that is in contact with the other end of the needle 8 is adjusted.

A movable iron core 22 is accommodated in the magnetic pipe 23 and the non-magnetic pipe 24 so as to be slidable in the axial direction while straddling both of them, and is further fixed inside the movable iron core 22 by a compression coil spring 28. One end of the needle 25 biased toward the iron core 21 is housed therein.
When the needle 25 moves toward the fixed core 21, the movable core 22 also moves toward the fixed core 21. When the movable core 22 moves toward the fixed core 21, the needle 25 moves.
The movable iron core 22 and one end of the needle 25 are also configured to move to the fixed iron core 21 side.

The electromagnetic coil 32 is located in the casing 11 so as to cover the respective ends of the fixed iron core 21 and the magnetic pipe 23 which sandwich the nonmagnetic pipe 24 and the periphery of the nonmagnetic pipe 24. . The metal plates 53 and 54 are positioned so as to cover the periphery of the spool 51 around which the wire is wound, and constitute the electromagnetic coil 32. Further, each end of the wire wound around the electromagnetic coil 32 is electrically connected to a plurality of terminals 34, and a voltage applied to the terminals 34 is applied to the electromagnetic coil 32.
It can be supplied to

As a result, a magnetic flux is generated when the electromagnetic coil 32 is energized, and the magnetic flux passes through a magnetic path formed by the metal plate 53, the magnetic pipe 23, the movable core 22, the fixed core 21, and the metal plate 54, and is fixed. An electromagnetic attraction force that attracts the movable iron core 22 to the iron core 21 is generated in the electromagnetic coil 32. Therefore, when the movable iron core 22 is attracted to the fixed iron core 21 side by this electromagnetic attraction force, the needle 25 also moves to the fixed iron core 21 side, and the energization of the electromagnetic coil 32 is cut off, and when the electromagnetic attraction force disappears, the compression coil spring 28 The movable iron core 22 and the needle 25 move toward the non-fixed iron core 21 side by the urging force.

As shown in FIG. 1, a valve body 26 as a valve body located at the end of the fuel injection valve 10 is welded and fixed to a non-magnetic pipe side end of the magnetic pipe 23 at a welding position 91. I have. The fuel passage of the adjusting pipe 29 and the fuel passage 2 of the fixed iron core 21 shown in FIG.
Fuel passages 27a and 27b communicating with 1a are formed. The fuel passage 27b is open at the end of the valve body 26, and forms an opening. Fuel passage 27a
Guide 2 on which the valve member 25a of the needle 25 described later slides on the inner wall surface of the valve body 26 forming the valve body 27b.
6a are formed. A valve seat 26b is formed on a conical slope formed continuously from the guide 26a to the opening end, and the valve member 25a of the needle 25 can be seated on the valve seat 26b.

The needle 25 slidable in the magnetic pipe 23 in the axial direction has a valve member 25a formed in a substantially frustoconical shape at the end opposite to the movable iron core. This valve member 25a
Are housed in the fuel passages 27a and 27b,
When it comes into contact with a valve seat 26b formed on the inner wall of the valve body 26, the communication between the fuel passage 27a and the fuel passage 27b can be shut off. Thereby, the valve seat 26
b, the communication between the fuel passage 27a and the fuel passage 27b is cut off, and when the valve member 25a separates from the valve seat 26b, the fuel passage 27a and the fuel passage 2
7b. Therefore, by controlling the axial movement of the needle 25 by energizing the electromagnetic coil 32 shown in FIG. 2, the seating or unseating of the valve member 25a is controlled, and the communication between the fuel passage 27a and the fuel passage 27b is interrupted. Or make it conductive. That is, the fuel passage 27
The pressurized fuel introduced to b is controlled by energizing the electromagnetic coil 32.

The nozzle plate 61 as an injection hole member is
For example, it is formed of a stainless steel plate, and is formed in a so-called cup shape having a bottomed cylindrical shape. Nozzle plate 6
Reference numeral 1 denotes a bottom portion 61a having a substantially disc shape, a cylindrical portion 61b as a side portion extending from the bottom portion 61a to the magnetic pipe 23 side,
Corner 61 provided between bottom 61a and cylindrical portion 61b
The cylindrical portion 61b is press-fitted and joined to the fuel downstream end of the valve body 26.

The bottom portion 61a covers an end face of the fuel passage 27b of the valve body 26, and a plurality of injection holes 61d are formed at a substantially central portion of the bottom portion 61a. This injection hole 61d
Is formed on the valve body 26 by the nozzle plate 61.
Is set at a position where it can communicate with the fuel passage 27b. As a result, the pressurized fuel flowing into the fuel passage 27b due to the separation of the valve member 25a is supplied to the injection hole 61d.
From the fuel injection valve 10. The injection hole 61d is formed by electric discharge, press working, or the like, and its inner diameter is adjusted so as to obtain a desired fuel flow rate. Injection hole 61d
For example, the inner diameter of the injection hole 61d and the thickness of the bottom 61a are formed in a predetermined fixed ratio such that the inner diameter is equal to the thickness of the bottom 61a.

The cylindrical portion 61b is press-fitted into the nozzle body 26 and is welded at a welding position 92 over the entire outer wall of the valve body 26 by welding. By welding with the cylindrical portion 61b, the distance between the valve seat portion 26b and the welding position 92 can be made longer than when a flat nozzle plate is used. Therefore, it is possible to prevent the valve seat portion 26b from being deformed due to heat generated when the nozzle plate 61 and the valve body 26 are joined by welding.

The cylindrical portion 61b has a substantially uniform thickness from the corner portion 61c to the end, and is formed to be smaller than the thickness of the bottom portion 61a. For this reason, the thickness of the cylindrical portion 61b can be set to a minimum necessary thickness regardless of the inner diameter of the injection hole 61d, and the rigidity of the cylindrical portion 61b can be made relatively small.

The method of forming the nozzle plate 61 is as follows.
The thickness of the cylindrical portion 61b can be easily made smaller than the thickness of the bottom portion 61a by performing a press-drawing drawing process on a flat stainless steel plate having a uniform thickness in a cup shape. Further, the thickness of the cylindrical portion 61b can be made smaller than the thickness of the bottom portion 61a by adding a drawing process after the press-drawing drawing process.

A resin protective cap 71 having a cylindrical side wall is fixed to the end of the nozzle plate 61. This protection cap 71 is
When 0 is attached to the intake pipe, the inner wall of the intake pipe and the fuel injection valve 10 come into contact with each other to prevent the injection hole 16d from being damaged. The inner diameter of the protection cap 71 is set to be substantially equal to the outer diameter of the nozzle plate 61.

Next, the operation of the fuel injection valve 10 will be described. (1) When the power to the electromagnetic coil 32 is turned off, the needle 2
5 is urged downward as shown in FIG. 2 by the urging force of the spring 28 together with the movable iron core 22, and the valve member 25a is seated on the valve seat 26b. Thereby, the fuel injection from the injection hole 16d is shut off.

(2) When the power supply to the electromagnetic coil 32 is turned on, the movable iron core 22 is attracted to the fixed iron core 21 against the urging force of the spring 28, so that the needle 25 is lifted. As a result, when the valve member 25a separates from the valve seat 26b, fuel is injected from the injection hole 16d.

Next, a comparative example in which the nozzle plate 61 of the first embodiment shown in FIG. 1 is changed to a cup shape having a uniform thickness will be described with reference to FIG. Other configurations are the same as those of the first embodiment, and the same components are denoted by the same reference numerals.

In the comparative example, as shown in FIG. 4, the nozzle plate 261 is formed in a cup shape having a uniform thickness. The nozzle plate 61 has a substantially disk-shaped bottom 2.
61a, a cylindrical portion 261b extending from the bottom 261a toward the magnetic pipe 23, and a corner 261c provided between the bottom 261a and the cylindrical portion 261b.
b is press-fitted and joined to the fuel downstream end of the valve body 26. A plurality of injection holes 261d are formed substantially at the center of the bottom 261a. The injection holes 261d are formed such that the inner diameter thereof is equal to the thickness of the bottom portion 261a, for example.
The inner diameter of 1d and the thickness of the bottom part 261a are formed in a predetermined constant ratio.

The cylindrical portion 261b has a substantially uniform thickness from the corner 261c to the end, and the thickness is formed to be equal to the thickness of the bottom 261a. Therefore, when the comparative example is applied to a fuel injection valve of a type having a relatively large fuel injection amount, that is, a relatively large injection hole diameter, as the inner diameter of the injection hole 261d becomes relatively large, the bottom portion 261a and the cylindrical portion 261b are formed. Is relatively thick. Therefore, the rigidity of the cylindrical portion 261b increases, and the cylindrical portion 261b is
When it is press-fitted into 6, the valve body 26 may be subjected to excessive compressive stress. When excessive compressive stress occurs in the valve body 26, the valve body 2 forming the fuel passages 27a and 27b
6, the guide portion 26a on which the valve member 25a of the needle 25 slides and the valve seat portion 26 with which the valve member 25a abuts.
The dimension of b changes, and the sliding of the valve member 25a becomes difficult, so that the fuel injection characteristics are deteriorated, or the sealing performance of the fuel when the valve member 25a is not operated is deteriorated. Has the problem of adversely affecting

Further, when the cylindrical portion 261b is press-fitted into the valve main body 26, it is conceivable to reduce the press-fit amount of the cylindrical portion 261b so as not to generate excessive compressive stress in the valve main body 26. However, it is difficult to determine the press-fit amount of the cylindrical portion 261b so as not to generate an excessive compressive stress in the valve body 26, and to manage the press-fit amount accuracy within the determined press-fit amount tolerance. It is. Therefore, there is a problem that manufacturing is difficult, and the number of manufacturing steps and manufacturing cost increase.

On the other hand, in the first embodiment, the thickness of the cylindrical portion 61b of the nozzle plate 61 is smaller than the thickness of the bottom portion 61a.
When 1b is press-fitted into the valve main body 26, it is possible to reliably prevent the generation of excessive compressive stress in the valve main body 26 regardless of the inner diameter of the injection hole 61d, and to prevent the inner walls of the valve main body 26 from forming the fuel passages 27a and 27b. The dimensional change can be reliably suppressed. Therefore, the guide portion 26a on which the valve member 25a slides is provided.
And the valve seat 26b with which the valve member 25a abuts is reliably prevented from changing in size, the sliding of the valve member 25a is improved, and the fuel injection characteristics are reliably improved. The sealing performance can be reliably improved.

Further, the thickness of the cylindrical portion 61b is adjusted to the bottom portion 61a.
The thickness can be easily reduced by press-drawing only a flat plate having a uniform thickness, or by adding a drawing step after press-drawing. Therefore, manufacturing is easy, and the number of manufacturing steps and manufacturing cost can be reduced.

(Second Embodiment) Next, in the nozzle plate 61 of the first embodiment shown in FIG. 1, the thickness of the cylindrical portion 61b and the thickness of the bottom portion 61a are made equal, and the thickness of the corner portion 61c is reduced. A second embodiment in which the thickness is smaller than the thickness of the bottom portion 61a will be described with reference to FIG. Other configurations are the same as those of the first embodiment, and the same components are denoted by the same reference numerals.

In the second embodiment, as shown in FIG. 3, the nozzle plate 161 is formed in a cup shape having a uniform thickness. The nozzle plate 161 includes a bottom portion 161a having a substantially disk shape, a cylindrical portion 161b extending from the bottom portion 161a to the magnetic pipe 23, a bottom portion 161a and the cylindrical portion 16a.
1b, and a cylindrical portion 161b is press-fitted and joined to the fuel downstream end of the valve body 26. A plurality of injection holes 161d are formed substantially at the center of the bottom 161a. The injection hole 161d is
For example, so that the inner diameter becomes equal to the thickness of the bottom 161a,
The inner diameter of the injection hole 161d and the thickness of the bottom 161a are formed in a predetermined constant ratio relationship.

The cylindrical portion 161b has a substantially uniform thickness from the corner 161c to the end, and is formed to have the same thickness as the bottom 161a. The corner 161c is the cylindrical part 1
Since it is formed smaller than the thickness of 61b and the bottom 161a, the rigidity of the corner 161c is reduced. For this reason, when the cylindrical portion 161b is press-fitted into the valve main body 26, the generation of excessive compressive stress in the valve main body 26 regardless of the inner diameter of the injection hole 161d is reliably prevented, and the fuel passages 27a and 27
The dimensional change of the inner wall of the valve body 26 forming the portion 7b can be reliably suppressed. Therefore, the guide portion 26a on which the valve member 25a slides and the valve seat portion 26b on which the valve member 25a abuts.
Is reliably suppressed, the sliding of the valve member 25a is satisfactorily improved, the fuel injection characteristics are reliably improved, and the sealing performance of the fuel when the valve member is not operated can be reliably improved.

Further, the thickness of the corner 161c is
1b and the thickness of the bottom portion 161a can be easily made by press-drawing and drawing a flat plate having a uniform thickness, and then adding a drawing process or deleting a part of the ridge portion. it can. Therefore, manufacturing is easy, and the number of manufacturing steps and manufacturing cost can be reduced.

In the above-described embodiments of the present invention, the cylindrical portion of the cup-shaped nozzle plate is press-fitted into the valve body and then directly welded to the outer wall of the valve body. The present invention can also be applied to a case in which is disposed downstream of the fuel and is joined to the valve body via a support member welded to the cylindrical portion of the nozzle plate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a fuel injection valve according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a fuel injection valve according to a first embodiment of the present invention.

FIG. 3 is a sectional view showing a main part of a fuel injection valve according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a fuel injection valve of a comparative example.

[Explanation of symbols]

 Reference Signs List 10 fuel injection valve 25a valve member 26 valve body (valve body) 26a guide portion 26b valve seat 27a fuel passage 27b fuel passage (opening) 61 nozzle plate (injection member) 61a bottom 61b cylindrical portion (side) 61c corner Part 61d Injection hole 161 Nozzle plate (injection hole member) 161a Bottom part 161b Cylindrical part (side part) 161c Corner part 161d Injection hole

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideto Takeda 1-1-1, Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (reference) 3G066 AA01 AB02 BA36 BA54 BA61 CC06U CC14 CC20 CC24 CC26 CE22 CE31

Claims (3)

[Claims] 1. A reciprocating valve member, a fuel passage through which pressurized fuel can flow, an opening for communicating the fuel passage with the outside at an outlet side of the fuel passage, and the valve member abutting. A valve body having a valve seat for interrupting communication between the fuel passage and the opening, a side portion joined to the valve body so as to cover the opening, and a side portion pressed into the valve body, and the opening A bottom having an injection hole communicating between the fuel injection port and the outside, and an injection hole member having stress reduction means for suppressing a dimensional change of an inner wall of the valve body forming the fuel passage at the time of press-fitting the side portion. And the fuel injection valve. 2. The fuel injection valve according to claim 1, wherein the stress reducing unit has a thickness at a side portion of the injection hole member smaller than a thickness at a bottom portion of the injection hole member. 3. The injection hole member has a corner portion provided between the side portion and the bottom portion, and the stress reducing means has a thickness of the corner portion greater than a thickness of the side portion and the bottom portion. The fuel injection valve according to claim 1, wherein the fuel injection valve is small.