JP2009019592A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a fuel injection valve for injecting fuel into an internal combustion engine. <P>SOLUTION: This fuel injection valve has a body for passing the fuel through its inside and forming a fuel injection hole, a valve element stored in the body and movable between a first position for blocking up the fuel injection hole and a second position for opening the fuel injection hole, a compression spring stored on the anti-fuel injection hole side of the valve element in the body and energizing the valve element toward the first position, and an actuator for moving the valve element toward the second position against energizing force of the compression spring. The body has a hollow core positioned on the anti-fuel injection hole side against the valve element and passing the fuel through its inner hole, and a hollow spring pin pressed in the inner hole of its core and abutting on the compression spring from the anti-fuel injection hole side. The spring pin is characterized by being formed of a copper alloy having sulfur resistance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that injects fuel into an internal combustion engine.

  Patent Document 1 describes a fuel injection valve that injects fuel into an internal combustion engine. This fuel injection valve includes a main body and a valve body accommodated in the main body. The main body has a fuel injection hole as well as fuel passing therethrough. The valve body is movable between a first position where the valve body comes into contact with the valve seat and closes the fuel injection hole, and a second position where the valve body leaves the valve seat and opens the fuel injection hole. The main body further includes a compression spring that biases the valve body toward the first position, and an actuator that moves the valve body toward the second position against the biasing force of the compression spring. ing. The actuator is configured using a solenoid. The solenoid is energized at the timing at which fuel should be injected. Thereby, the fuel injection hole is opened at the timing when the fuel is to be injected, and the fuel is injected from the fuel injection hole.

  The main body of the fuel injection valve includes a hollow core through which fuel passes through the inner hole, and a hollow spring pin (referred to as an adjustment bush in Patent Document 1) that is press-fitted into the inner hole of the core. . The core is positioned on the side opposite to the fuel injection hole with respect to the valve body, and the spring pin press-fitted into the inner hole of the core is in contact with the compression spring from the side opposite to the fuel injection hole. Patent Document 1 describes that non-rust spring steel, bronze, brass, tonback and copper beryllium are useful as a material for forming the spring pin.

JP-A-5-87264

Since the spring pin press-fitted into the inner hole of the core is exposed to fuel passing through the inner hole of the core, corrosion resistance to the fuel is required. For this reason, a material excellent in corrosion resistance against fuel is used as a material for forming the spring pin. However, in the conventional fuel injection valve, the corrosion of the spring pin proceeds at an abnormal speed, and the function of the fuel injection valve may deteriorate early. The fuel injection valve which investigated the cause and took the countermeasure is required.
The present invention solves the above problems. The present invention provides a fuel injection valve capable of suppressing the corrosion of a spring pin and maintaining its function over a long period of time.

A fuel injection valve embodied by the present invention includes a main body in which fuel passes and a fuel injection hole formed therein, and a first position that is accommodated in the main body and closes the fuel injection hole. And a valve body movable between the second position for opening the fuel injection hole and the valve body in the main body, the valve body is accommodated on the side opposite to the fuel injection hole, and the valve body is moved to the first position. A compression spring that is biased toward the end; and an actuator that moves the valve body toward the second position against the biasing force of the compression spring.
In this fuel injection valve, the main body is positioned on the side opposite to the fuel injection hole with respect to the valve body, and a hollow core through which the fuel passes and a press fit into the inner hole of the core. A hollow spring pin is provided in contact with the compression spring from the side opposite to the fuel injection hole. And the said spring pin is formed with the copper alloy which has sulfur tolerance, It is characterized by the above-mentioned.

For example, an automobile equipped with a fuel injection valve is refueled many times at an unspecified gas station. For this reason, the quality of fuel supplied to the automobile is not always constant, and poor quality fuel may be supplied. Poor quality fuel often contains a large amount of sulfur, and if poor quality fuel is frequently supplied, sulfidation corrosion of the spring pin may proceed at an abnormal rate.
For the above event, in the fuel injection valve according to the present invention, the spring pin is formed of a copper alloy having sulfur resistance. Therefore, even when not only a bad fuel but also a fuel containing a relatively large amount of sulfur is used, corrosion of the spring pin is suppressed.
In the fuel injection valve according to the present invention, the corrosion of the spring pin is suppressed, and its function can be maintained over a long period of time.

The spring pin is preferably a copper alloy containing 5 weight percent or more of at least one of nickel, silicon, aluminum, and chromium.
This type of copper alloy has significant corrosion resistance to sulfur. Therefore, if the spring pin is formed of this type of copper alloy, the corrosion of the spring pin can be remarkably suppressed.

More preferably, the spring pin is made of white (a copper alloy mainly composed of copper-nickel-zinc).
The position of the spring pin press-fitted into the inner hole of the core needs to be maintained against the urging force from the compression spring. For this reason, the spring pin needs to have sufficient strength and be firmly fitted in the inner hole of the core.
Western white has sufficient strength as well as corrosion resistance to sulfur. Therefore, if the spring pin is made of white, corrosion of the spring pin can be suppressed and the spring pin can be strongly fitted into the inner hole of the core.

The invention is also embodied in other new and useful fuel injectors. The fuel injection valve includes a main body through which fuel passes and a fuel injection hole formed therein, and is accommodated in the main body, and includes a first position for closing the fuel injection hole and the fuel injection hole. A valve body movable between the second position to be opened and the valve body in the main body are accommodated on the side opposite to the fuel injection hole, and urges the valve body toward the first position. A compression spring, and an actuator for moving the valve body toward the second position against the urging force of the compression spring.
In this fuel injection valve, the main body is positioned on the side opposite to the fuel injection hole with respect to the valve body, and a hollow core through which the fuel passes and a press fit into the inner hole of the core. A hollow spring pin is provided in contact with the compression spring from the side opposite to the fuel injection hole. And the surface of the said spring pin is coat | covered with the film which has a sulfur tolerance.
Also in this fuel injection valve, corrosion of the spring pin due to sulfur is suppressed, and its function can be maintained over a long period of time.

The sulfur resistant coating is preferably a Ni-P alloy plating layer.
The Ni-P alloy plating layer has sufficient corrosion resistance against sulfur. By forming the Ni-P alloy plating layer on the surface of the spring pin, corrosion of the spring pin can be remarkably suppressed.

In the fuel injection valve according to the present invention, it is preferable that the outer peripheral surface of the spring pin in contact with the core is subjected to a roughening process.
When the material of the spring pin is changed according to the present invention, the force required to press-fit the spring pin into the inner hole of the core may increase. In this case, if the surface of the outer peripheral surface of the spring pin is roughened, the required pressure input can be reduced.

The treatment for roughening the surface is preferably shot peening.
According to the shot peening, the outer peripheral surface of the spring pin can be relatively easily and moderately roughened.

  According to the present invention, for example, even when poor fuel is used, it is possible to prevent the function of the fuel injection valve from being deteriorated early. The lifetime of the fuel injection valve can be significantly increased.

Preferred embodiments of the present invention will be listed.
(Mode 1) The main body includes a body, a core fixed in the body, and a valve seat fixed to one end side of the body and formed with a fuel injection hole. The valve body accommodated in the main body is located between the core and the valve seat. The valve body moves between a first position where one end abuts the valve seat and closes the fuel injection hole, and a second position where one end is separated from the valve seat and the other end abuts the core.
(Mode 2) One end of the valve body is provided with a closing portion that contacts the valve seat and closes the fuel injection hole.
(Mode 3) The actuator is configured using a solenoid. The core and the valve body are formed using a magnetic material, and when the solenoid is energized, the core and the valve body are magnetized.
(Mode 4) The spring pin is a hollow cylindrical member and has a slit extending in the longitudinal direction.

  A fuel injection valve embodying the present invention will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional view of a fuel injection valve 10 of the embodiment. As shown in FIG. 1, the fuel injection valve 10 includes a main body 12, a valve body 30, a compression spring 24, and a solenoid 26.

A fuel flow path 20 through which fuel passes is formed inside the main body 12. An arrow A in FIG. 1 indicates the fuel passing direction. A fuel injection hole 42 is formed at the downstream end 12 d of the main body 12. A fuel pipe (not shown) extending from a fuel tank (not shown) is connected to the upstream end 12 c of the main body 12. The fuel flow path 20 communicates from the upstream end 12 c of the main body 12 to the fuel injection hole 42.
In this specification, the expressions “upstream” and “downstream” mean “upstream with respect to the fuel passage direction A” and “downstream with respect to the fuel passage direction A”, respectively. That is, the expressions “upstream” and “downstream” correspond to “upper” and “lower” in FIG. 1, respectively.

The configuration of the main body 12 will be described in more detail. As shown in FIG. 1, the main body 12 includes a body 14, a core 16, a spring pin 22, a valve seat holder 32, and a valve seat 34.
The body 14 is a cylindrical member that constitutes the outline of the main body 12. The body 14 is made of resin. A connector 48 connected to an external control unit (not shown) is formed on the outer peripheral surface of the body 14. The connector 48 is provided with a plurality of terminal pins 50 that are electrically connected to the solenoid 26.
The core 16 is a hollow cylindrical member formed of a magnetic material, and is fixed to the through hole 14 a of the body 14. A part of the core 16 protrudes upstream from the through hole 14 a of the body 14. The downstream end 16 d of the core 16 is located in the through hole 14 a of the body 14. The through hole 16 a of the core 16 constitutes a part of the fuel flow path 20. A filter 18 for removing foreign matter from the fuel is provided in the through hole 16a of the core 16. The core 16 is located on the side opposite to the fuel injection hole 42 (upstream side) with respect to the valve body 30.

  The spring pin 22 is press-fitted into the through hole 16 a of the core 16. The spring pin 22 is located on the upstream side of the compression spring 24 and is in contact with the upstream end 24 c of the compression spring 24. The spring pin 22 is a member for adjusting the compression amount of the compression spring 24 by adjusting the press-fitting position. The spring pin 22 is a hollow cylindrical member, and the through hole 22 a constitutes a part of the fuel flow path 20. The spring pin 22 will be described in more detail later.

The valve seat holder 32 is a cylindrical member and is fixed to the through hole 14 a of the body 14. The valve seat holder 32 is located on the downstream side of the core 16, and a part of the valve seat holder 32 projects downstream from the through hole 14 a of the body 14. A valve body 30 is accommodated in the through hole 32 a of the valve seat holder 32. Between the through hole 32 a of the valve seat holder 32 and the valve body 30, a gap constituting a part of the fuel flow path 20 is formed. At the upstream end of the valve seat holder 32, a cylindrical sleeve 28 formed of a nonmagnetic material is provided. In the through hole 28 a of the sleeve 28, the downstream end 16 d of the core 16 and the upstream end 30 c of the valve body 30 are located. The valve body 30 is slidable with respect to the through hole 28 a of the sleeve 28.
The valve seat 34 is a bottomed cylindrical member, and is fixed to the through hole 32 a of the valve seat holder 32. A downstream portion of the valve element 30 is located in the inner hole 34 a of the valve seat 34. Between the inner hole 34 a of the valve seat 34 and the valve body 30, a gap constituting a part of the fuel flow path 20 is formed. An orifice plate 38 is provided on the downstream end face of the valve seat 34. The valve seat 34 and the orifice plate 38 are located at the downstream end 12 d of the main body 12. Each of the valve seat 34 and the orifice plate 38 is formed with through holes 34 a and 38 a constituting the fuel injection hole 42.

Next, the configuration of the valve body 30 will be described. The valve body 30 is a bottomed cylindrical member and is made of a magnetic material. The valve body 30 is accommodated in the through hole 32a of the valve seat holder 32, and is supported so as to be slidable in a direction parallel to the fuel passing direction A. The downstream end 24 d of the compression spring 24 is in contact with the valve body 30.
The upstream end 30 c of the valve body 30 faces the downstream end 16 d of the core 16 that is a part of the main body 12. A closing portion 36 for closing the fuel injection hole 42 is provided at the downstream end 30 d of the valve body 30. The inner hole 30 a of the valve body 30 communicates with the through hole 16 a of the core 16 and constitutes a part of the fuel flow path 30. A plurality of through holes 30 b are formed in the side wall of the valve body 30, and the inner hole 30 a of the valve body 30 communicates with a gap between the inner surface 34 a of the valve seat 34 and the valve body 30.

  The valve body 30 is movable between a first position where the fuel injection hole 42 is closed as shown in FIG. 2 and a second position where the fuel injection hole 42 is opened as shown in FIG. The first position is a movement limit on the downstream side (fuel injection hole 42 side) of the valve body 30, and the second position is a movement limit on the upstream side (anti-fuel injection hole 42 side) of the valve body 30. As shown in FIG. 2, when the valve body 30 is in the first position, the closing portion 36 that is the downstream end of the valve body 30 comes into contact with the valve seat 34, and the fuel injection hole 42 is closed. At this time, the upstream end 30 c of the valve body 30 is separated from the downstream end 16 d of the core 16. On the other hand, as shown in FIG. 3, when the valve body 30 is in the second position, the closing portion 36, which is the downstream end of the valve body 30, is separated from the valve seat 34 and the fuel injection hole 42 is opened. At this time, the upstream end 30 c of the valve body 30 is in contact with the downstream end 16 d of the core 16.

Next, the compression spring 24 and the solenoid 26 will be described. The compression spring 24 is accommodated in the through hole 16 a of the core 16. The compression spring 24 is positioned between the spring pin 22 and the valve body 30 in a compressed state. An upstream end 24 c of the compression spring 24 is in contact with the spring pin 22, and a downstream end 24 d of the compression spring 24 is in contact with the valve body 30. The compression spring 24 urges the valve body 30 to the first position (see FIG. 2), which is the downstream movement limit, by its elastic force.
The solenoid 26 is fixed in the through hole 14 of the body 14. The solenoid 26 surrounds a part including the downstream end 16 c of the core 16. A current is supplied to the solenoid 26 from an external control unit (not shown) via the terminal pin 50 of the connector 48. A current is passed through the solenoid 26 at a timing at which fuel should be injected. The solenoid 26 generates a magnetic field when a current is applied.

Next, the operation of the fuel injection valve 10 will be described. Fuel flows into the main body 12 of the fuel injection valve 10 from a fuel pipe (not shown) connected to the upstream end 12c. The inflowing fuel passes through the fuel flow path 20 and reaches the fuel injection hole 40 formed in the downstream end 12d in the main body 12. When no current is supplied to the solenoid 26, the valve body 30 is maintained at the first position by the urging force of the compression spring 24 (see FIG. 2). In this case, since the fuel injection hole 42 is closed by the closing part 36 of the valve body 30, fuel is not injected from the fuel injection hole 42.
On the other hand, when a current is passed through the solenoid 26 and the solenoid 26 generates a magnetic field, the core 16 and the valve body 30 become magnetized. The core 16 and the valve body 30 attract each other, and the valve body 30 moves to the upstream second position against the urging force of the compression spring 24 (see FIG. 3). The closing portion 36 of the valve body 30 is separated from the valve seat 34, and the fuel injection hole 42 is opened. At this time, fuel is injected from the fuel injection hole 42. Usually, current is intermittently supplied to the compression spring 24, and fuel is intermittently injected from the fuel injection hole 46.

The overall structure and operation of the fuel injection valve 10 of this embodiment have been described above. Subsequently, a detailed description of the configuration of the spring pin 22 will be added.
FIG. 4 shows the spring pin 22 alone. As shown in FIG. 4, the spring pin 22 is formed with a slit 22e extending in the longitudinal direction. The outer peripheral surface 22f that contacts the core 16 of the spring pin 22 is shot peened, and is an uneven surface with a large surface roughness. When the outer peripheral surface 22f of the spring pin 22 is an uneven surface, the pressure input required when the spring pin 22 is press-fitted into the through hole 16a of the core 16 can be reduced. In addition, an uneven surface can also be formed on the outer peripheral surface 22f of the spring pin 22 by, for example, rolling using a mold for transferring the unevenness.

The spring pin 22 is exposed to fuel passing through the inner hole 16 a of the core 16. Therefore, the spring pin 22 is required to have corrosion resistance against fuel. The quality of the fuel used is not necessarily constant. For example, a fuel containing a large amount of impurities such as poor gasoline or LPG may be used. Therefore, the spring pin 22 is required to have corrosion resistance against impurities contained in the fuel.
The inventor has confirmed that corrosion of the spring pin 22 due to sulfur is a problem among impurities contained in the fuel. Sulfide generated by sulfidation corrosion of the spring pin 22 easily accumulates between the valve body 30 and the valve seat 34, and the fuel injection hole 42 is likely to be blocked. Therefore, as a result of experiment on corrosion resistance to sulfur (sulfur resistance) for various materials, a copper alloy containing at least one of nickel, silicon, aluminum, and chromium by 5 weight percent or more is good for sulfur. It was confirmed that it has corrosion resistance (sulfur resistance). These elements easily react with oxygen ions in the air or fuel, and an oxide film thereof is easily formed on the surface of the spring pin 22. In particular, when these elements are contained in an amount of 5 weight percent or more, those oxide films are sufficiently formed on the surface of the spring pin 22, and corrosion of the spring pin 22 due to sulfur is significantly suppressed. Therefore, when the spring pin 22 is formed of a copper alloy containing at least one of nickel, silicon, aluminum, and chromium by 5 weight percent or more, corrosion of the spring pin 22 is suppressed even when, for example, poor fuel is frequently used. Thus, the function of the fuel injection valve 10 is maintained over a long period of time. That is, problems such as poor closing of the fuel injection hole 42 due to the accumulation of sulfide between the valve body 30 and the valve seat 34 and the reduction of the fuel injection amount due to the accumulation of sulfide in the fuel injection hole 42 occur. Is prevented.

Examples of the copper alloy include white copper C7060 (containing 9-11 weight percent nickel) and white C7701 (containing 16.5-19.5 weight percent nickel). In addition, Western white C7701 contains a relatively large amount of zinc (about 20 weight percent).
In this embodiment, the spring pin 22 is formed of white C7701. Western white C7701 has good sulfur resistance and relatively high strength (high Young's modulus). Therefore, the spring pin 22 formed by the white C7701 can be firmly fitted into the inner hole 16a of the press-fitted core 16 and can continue to restrain the upstream end 24c of the compression spring 24.

  The spring pin 22 may be coated with a material excellent in sulfur resistance instead of being formed of the above-described copper alloy having sulfur resistance. About the material which coat | covers the spring pin 22, it is not restricted only to the copper alloy which has the above-mentioned sulfur tolerance, Ni-P alloy may be sufficient. The Ni—P alloy can easily form a stable film by plating.

The technical elements described in the present specification or 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 usefulness by achieving one of them.

The longitudinal cross-sectional view of a fuel injection valve. The figure which shows the state which has a valve body in a 1st position. The figure which shows the state which has a valve body in a 2nd position. The figure which shows a spring pin alone.

Explanation of symbols

10: Fuel injection valve 12: Body 14: Body 16: Core 20: Fuel flow path 22: Spring pin 24: Compression spring 26: Solenoid 30: Valve body 34: Valve seat 38: Closed portion (one end of the valve body)
42: Fuel injection hole

Claims (7)

A body through which fuel passes and a fuel injection hole is formed;
A valve body that is accommodated in the main body and is movable between a first position for closing the fuel injection hole and a second position for opening the fuel injection hole;
A compression spring that is accommodated closer to the fuel injection hole than the valve body in the main body, and biases the valve body toward the first position;
An actuator for moving the valve body toward the second position against an urging force of the compression spring;
The main body is positioned on the side opposite to the fuel injection hole with respect to the valve body, and a hollow core through which the fuel passes, and is press-fitted into the inner hole of the core and is against the compression spring. It has a hollow spring pin in contact with the fuel injection hole side,
The fuel injection valve according to claim 1, wherein the spring pin is made of a copper alloy having sulfur resistance.   2. The fuel injection valve according to claim 1, wherein the spring pin is a copper alloy containing at least one of nickel, silicon, aluminum, and chromium by 5 weight percent or more.   The fuel injection valve according to claim 2, wherein the spring pin is formed of white and white. A body through which fuel passes and a fuel injection hole is formed;
A valve body that is accommodated in the main body and is movable between a first position for closing the fuel injection hole and a second position for opening the fuel injection hole;
A compression spring that is accommodated closer to the fuel injection hole than the valve body in the main body, and biases the valve body toward the first position;
An actuator for moving the valve body toward the second position against an urging force of the compression spring;
The main body is positioned on the side opposite to the fuel injection hole with respect to the valve body, and a hollow core through which the fuel passes, and is press-fitted into the inner hole of the core and is against the compression spring. It has a hollow spring pin in contact with the fuel injection hole side,
The fuel injection valve, wherein the surface of the spring pin is covered with a film having sulfur resistance.   The fuel injection valve according to claim 4, wherein the coating film having sulfur resistance is a Ni-P alloy plating layer.   6. The fuel injection valve according to claim 1, wherein the outer peripheral surface of the spring pin that comes into contact with the core is subjected to a surface roughening process.   The fuel injection valve according to claim 6, wherein the treatment for roughening the surface is shot peening.

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