JP2000045913A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve cost reduction and improve spray characteristic balance of the distributed fuel, in a fuel injection valve of an internal combustion engine that injects fuel in an uneven distribution inn two directions. SOLUTION: An orifice plate 5 is closely fixed to an end surface of a valve body 3 that defines a downstream portion of a fuel passage 1a. The orifice plate 5 has two types of jet holes 501, 502 formed to face two directions at an acute angle with respect to an axial line C direction of the valve body 3. Fuel is distributively injected from the jet holes 501, 502 in the two directions. All of the jet holes 501, 502 have the same diameter, so that forming of the jet holes can be facilitated and spray characteristic balance of the distributed fuel can be improved. The ratio of the number of the jet holes 501 of the first type jet hole to that of the jet holes 502 of the second type jet hole is set to be an uneven predetermined value. Thus, the fuel is injected in an uneven distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection valve for an internal combustion engine.

[0002]

2. Description of the Related Art In a so-called multi-valve internal combustion engine having a plurality of intake valves, a fuel injection valve capable of distributing and injecting fuel in two directions is used so that fuel can be efficiently sent to each intake valve.

In a multi-valve internal combustion engine, an intake valve that receives one of the distributed and injected fuel flows is operated in a substantially closed state, thereby causing a swirl flow in the combustion chamber and causing a lean burn in a low engine speed range. There is something that is made to perform effectively. However, in this case, the fuel may accumulate around the substantially closed intake valve and deteriorate the exhaust emission. Therefore, in such an internal combustion engine, the fuel injection valve may be configured such that the injection amount is not uniform at a predetermined ratio. Is used to reduce the proportion of fuel directed toward the substantially closed intake valve.

FIG. 4A shows an enlarged cross section of a tip portion of such a fuel injection valve, and FIG.
3 shows a cross section along the line VB-IVB. The fuel injection valve 8 includes a valve body 81 at a downstream portion of a fuel flow path 8a through which the fuel delivered from the fuel tank flows, and the valve body 81 is opened and closed by a valve body. The downstream end of the fuel flow path 8a is closed by an orifice plate 83. The orifice plate 83 has a plurality of injection holes 83.
1, 832 are formed, and the fuel is sprayed.

[0005] The injection holes 831 and 832 are provided in the valve body 81.
2 so as to face two directions forming an acute angle with respect to the axis C direction of
The two types are formed and distributed and injected in the direction of the two intake valves. Then, the ratio between the diameter of the injection hole forming the first type injection hole 831 and the diameter of the injection hole forming the second type injection hole 832 is set according to the ratio of the fuel to be distributed and injected. Are not uniform.

The injection holes 831 and 832 are formed by a method such as press working or electric discharge machining.
For example, in the case of drilling by press working, the orifice plate and the die before working are placed on a jig configured to have a variable tilt angle, and the tilt angle of the jig is determined by the injection hole. After the direction to be formed is matched with the direction of the punch, the hole is punched.

[0007]

By the way, in the fuel injection valve 8 in which the distribution ratio of the fuel is not equal, the injection holes 83
Since 1,832 has a different diameter in addition to the forming direction, there is the following problem in the injection hole forming process. That is, for example, in the case of the press working described above, after forming one type of injection hole, it is necessary to replace the punch with a different size for forming the other type of injection hole, which complicates the operation. .
It suffices if two press machines can be prepared: a dedicated machine for large-diameter injection holes and a dedicated machine for small-diameter injection holes. However, there is a problem in equipment such as an increase in equipment costs and securing of an installation place. For this reason, it has been difficult to reduce the manufacturing cost of the fuel injection valve.

In addition, the smaller the ratio of fuel toward the substantially closed intake valve, the larger the diameter of the injection holes 831 and 832 becomes. The diameter of the injection holes 831 and 832 is
Since this affects the spray characteristics of the fuel injected from the nozzles 31 and 832, the spray characteristics become more unbalanced as the ratio of the fuel toward the substantially closed intake valve is reduced.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a fuel injection valve which can be manufactured at low cost and has a well-balanced spray characteristic of injected fuel distributed in two directions.

[0010]

According to the first aspect of the present invention, a valve body is provided downstream of the fuel flow passage, and the valve body is opened and closed by the valve body. The downstream end of the fuel flow path is closed by an orifice plate. Two types of injection holes are formed in the orifice plate so as to point in two directions at an acute angle with respect to the axial direction of the valve body, and the injection amount of fuel from the injection holes in the two directions is non-uniform at a predetermined ratio. It is configured to perform the distributed injection so as to be as follows. In addition to this configuration, the first
The ratio of the number of the injection holes constituting the type of injection holes to the number of the injection holes constituting the second type of injection holes is the predetermined ratio, and,
The diameter of all injection holes is the same.

By forming the injection hole as described above,
The ratio of the total passage cross-sectional area of the first type injection hole to the total passage cross-sectional area of the second type injection hole is the ratio of the number of the first type injection holes to the number of the second type injection holes. . Thus, the fuel is distributed at the predetermined ratio.

Since the diameter of the injection hole is single, the manufacturing process is simplified as compared with a conventional fuel injection valve (see FIG. 4) in which two types of injection holes having different diameters are formed in one orifice plate.
It can be manufactured at low cost. Further, since the distribution ratio of the fuel is not controlled by the diameter of the injection hole, the spray characteristics of the distributed injected fuel can be made the same regardless of the distribution ratio.

According to the second aspect of the present invention, the injection holes are formed at equal intervals on a circle centered on the axis of the valve body.

Since the injection holes are formed at equal intervals on the circle and are symmetrical with respect to the axis, and all the injection holes have the same diameter, at the immediately upstream portion of the orifice plate,
The fuel forms a balanced flow that is symmetric about the axis. Thus, the injection state of each injection hole is stable, and the fuel injection valve has two types of injection holes having different diameters (see FIG. 4).
The spray direction is constant and uniform fine spray can be obtained as compared with a fuel injection valve in which nozzles and injection holes are located at non-equidistant positions.

[0015]

FIG. 1A is an enlarged sectional view of a tip portion of a fuel injection valve according to the present invention, and FIG. 1B is a sectional view taken along line IB-IB in FIG. 1A. FIG. 2 shows an overall cross section of the fuel injection valve of the present invention. The fuel injection valve 1 has a fuel passage 1
A general configuration in which a needle 41 as a valve body opens and closes a valve body 3 that forms a downstream portion of a, and injects fuel from injection holes 501 and 502 formed in an orifice plate 5 that is in close contact with an end surface of the valve body 3. belongs to. The feature of the present invention resides in the orifice plate 5, which will be described later. First, the overall configuration of the fuel injection valve 1 will be described.

The fuel injection valve 1 has a housing mold 2 made of resin, and a valve body 3 is fitted to a tip of the housing mold 2 via a magnetic pipe 61. The valve body 3 is fitted into the magnetic pipe 61 via a disk-shaped spacer 62 and is laser-welded to the magnetic pipe 61. Through holes 621 and 622 are formed in and around the center of the spacer 62 so that the inside of the valve body 3 and the magnetic pipe 61 communicate with each other.

In the housing mold 2, a non-magnetic pipe 63 and a fixed core 64 are provided coaxially above the magnetic pipe 61, and the fixed core 64 protrudes from the upper end of the housing mold 2. The fixed iron core 64 is a cylindrical member having both ends opened, and the upper end opening 641 is a fuel inlet 641.
The fuel flow from the fuel inlet 641 along the axis C of the fuel injection valve 1 reaches the valve body 3 via the fixed iron core 64, the non-magnetic pipe 63, the magnetic pipe 61, and the spacer 62. A road 1a is formed. In the fixed iron core 64, a filter 6 is provided immediately below the fuel inlet 641.
5 are provided to remove foreign matter such as dust in the fuel.

In the fuel flow path 1a, the needle 4 is disposed on the tip side of the nonmagnetic pipe 63, and the movable iron core 66 is disposed above the needle 4. The needle 4 includes a joint portion 43 between the valve body portion 41, the shaft portion 42, and the movable iron core 66. The sliding portion 412 of the valve body portion 41 is in sliding contact with the inner peripheral surface 3a of the valve body 3. The movable core 66 is a cylindrical member having both ends opened and made of a magnetic material, and is slidably held by the nonmagnetic pipe 63. The joint 43 of the needle 4 is fitted into the movable iron core 66 from below,
The movable iron core 66 and the needle 4 are laser-welded. Thus, the needle 4 can be displaced along the axis C.

The sliding portion 412 of the needle 4 has a four-chamfered portion formed on the peripheral surface so that fuel can flow freely. Further, the joining portion 43 of the needle 4 has a two-chamfered portion formed on the peripheral surface, so that fuel can freely flow between the joining portion 43 and the movable iron core 66.

The valve body 41 of the needle 4 is connected to the fuel passage 1a.
Is housed in a valve body 3 forming a downstream portion of the valve body. The inner peripheral surface 3 a of the valve body 3 is formed coaxially with the needle 4 on the outer periphery of the valve body 41. The inner peripheral surface 3a is formed as a conical surface 3b that is slidably contacted with the sliding portion 412 of the valve body portion 41 in the middle in the axial direction, and that has a diameter smaller than the slidable contact portion toward the lower opening end.

The tip 411 of the valve body 41 is connected to the fuel flow path 1.
a having a larger diameter than the opening diameter at the downstream end of
An annular contact surface facing the conical surface 3b of the valve body 3 is formed at the lower end of the peripheral surface 4a of the valve body 3, and the conical surface 3b is used as a valve seat as a seat portion 4b to be seated thereon.

The valve body 41 has a flange 413 above the sliding part 412. Flange 413
Is slightly larger in diameter than the through hole 621 of the spacer 62 through which the shaft portion 42 is inserted, and defines the lift position of the needle 4. The lift amount is between the upper end surface of the valve body 3 and the flange 41.
The lift amount is adjusted by the amount of shaving of the upper end surface of the valve body 3. At this time, dimensions and the like of each member are set so that a predetermined gap is formed between the upper end surface of the movable iron core 66 and the lower end surface of the fixed iron core 64.

Next, the driving means of the needle 4 will be described. In the fixed iron core 63, a compression coil spring 67 and an adjusting pipe 68 for defining the upper end position thereof are provided along the axis C above the movable iron core 66. Thus, the needle 4 is urged downward.

A solenoid 7 for sucking the movable iron core is provided in the housing mold 2. Solenoid part 7
Is provided with a resin spool 71 on the outer periphery of a magnetic pipe 61, a non-magnetic pipe 63, and a fixed iron core 64, and an electromagnetic coil 72 wound therearound. On the outer periphery of the spool 71 and the electromagnetic coil 72, Projecting portion 7 projecting above cylindrical tubular portion 731 surrounded by housing mold 2
The protrusion 732 protects a lead wire 74 electrically derived from the electromagnetic coil 72 and holds a terminal 75 described later.

In the housing mold 2, two metal plates 76 are provided. Metal plate 7
Reference numerals 6 and 76 denote members that form a magnetic path through which a magnetic flux passes when the electromagnetic coil 72 is energized. The upper end is in contact with the outer peripheral surface of the fixed iron core 64, and the lower end is in contact with the outer periphery of the magnetic pipe 61. Provided.

At an upper portion of the housing mold 2, a connector portion 21 projects obliquely upward. A terminal 75 is buried in the connector portion 21 except for a distal end portion, and is connected to a lead wire 74 drawn out from an electromagnetic coil 72. The terminal 75 is connected to an electronic control unit (not shown) via a wire harness. The electronic control unit is energized to the electromagnetic coil 72 through the terminal 75 to excite the electromagnetic coil 72, and the movable core 66 is compressed by the compression coil spring 67. The needle 4 is lifted by suction toward the fixed iron core 64 against the urging force of.

When the needle 4 is lifted, the fuel inlet 6
The fuel that has flowed in through the filter 41 is cleaned by the filter 65, and the compression coil spring 6 is moved through the adjusting pipe 68.
7, through the gap between the movable iron core 66 and the two-chamfered portion formed on the needle 4, and further through the gap between the movable iron core 66 and the four-chamfered portion of the needle 4 of the valve body 3,
It reaches the injection holes 501 and 502 of the orifice plate 5.

Next, the orifice plate 5 which is a feature of the present invention will be described. In the following description, it is assumed that the predetermined ratio of fuel to be distributed between the direction of the open intake valve and the direction of the closed intake valve is 3: 2. The orifice plate 5 is a disk made of stainless steel and has a cylindrical mounting portion 51 erected from the peripheral portion, and is fitted to the valve body 3. Then, it is welded to the valve body 3 at the mounting portion 51 in a state of being in close contact with the end face of the valve body 3 and closing the downstream end of the fuel flow path 1a. The valve body 3 and the orifice plate 5
Instead of being formed separately from the above, they may be integrally formed. That is, instead of the separate valve body and the orifice plate, a cylindrical member having an inner peripheral surface similar to the inner peripheral surface 3a and having one end closed is formed, and an injection hole is formed using the end wall as an orifice plate.

The orifice plate 5 has a total of 5
Two injection holes 501 and 502 are formed at equal intervals on a circle A about the axis C. Three injection holes 501 on the left side in the figure
Are formed so as to face the direction of the open-side intake valve (slightly leftward in the drawing) that forms an acute angle with respect to the axis C (first type injection holes), while the two injection holes on the right side in the drawing are formed. 502 is
The second side injection hole is formed so as to face the direction of the closed side intake valve (slightly rightward in the figure) which forms an acute angle with respect to the axis C so that the fuels F1 and F2 are distributed and injected. Has become. Here, the number (3) of injection holes of the first type of injection holes (hereinafter, open side injection holes) 501 and the number of injection holes of the second type (hereinafter,
The ratio of the number of injection holes (closed injection holes) 502 (2) is a predetermined ratio (here, 3: 2) of the fuel to be distributed and injected.

The injection holes 501 and 502 differ only in the forming direction, and all the injection holes 501 and 502 have the same diameter.

The operation of the fuel injection valve 1 will be described. When the terminal 75 is energized, the electromagnetic coil 72 is excited to attract the movable iron core 66, whereby the needle 4 is lifted. The fuel passes through the fuel flow path 1a, passes between the seat portion 4b of the needle 4 and the conical surface 3b serving as a valve seat, reaches the inlet surface 5a of the orifice plate 5, and is directed from the open injection hole 501 to the open intake valve. As a result, fuel F1 is injected, and fuel F2 is injected from the closed-side injection hole 502 toward the closed-side intake valve.

The total cross-sectional area of the passage of the open-side injection hole 501 is obtained by multiplying the cross-sectional area of the passage by the number of the injection holes.
Is the product of the passage sectional area and the number of injection holes. Number of open orifices 501 and closed orifices 50
The ratio of the number of injection holes of No. 2 is 3: 2, and the diameter of all the injection holes 501 and 502 is the same.
The ratio of the total passage cross-sectional area to the total passage cross-sectional area of the closed injection hole 502 is also the ratio (3: 2). Thus, the amount of fuel F1 and the amount of fuel F2 are distributed at a predetermined ratio (3: 2).

Further, since the distribution ratio of the fuel is controlled by the ratio of the number of injection holes and the diameters of all the injection holes 501 and 502 are made the same, the spray characteristic is not affected by the distribution ratio.
1 and the closed side injection hole 502 are the same.

The injection holes 501 and 502 are formed by press working or electric discharge working as in the prior art. In the present fuel injection valve 1, the diameter of all the injection holes 501 and 502 is the same as in a fuel injection valve that distributes and injects in two directions evenly, so that only one punch may be used. That is, as in the case where the injection hole is formed in the orifice plate of the fuel injection valve that uniformly distributes and injects, the orifice plate before the injection hole formation is mounted on a jig having a variable inclination angle, and the orifice plate is formed. If all the injection holes are press-formed while changing the inclination angle and position, the orifice plate is completed. There is no need to replace the punch with respect to one orifice plate, and there is no need to provide another press machine, so that cost reduction can be realized. Even if the processing method is another method, for example, electric discharge machining, the same effect of simplifying the injection hole forming step can be obtained.

In the present fuel injection valve 1, all the injection holes 501, 502 have the same diameter, and the injection holes 501, 5
Since 02 are formed at equal intervals on the circle A centered on the axis C, the following effects are obtained. That is, in the conventional fuel injection valve 8 shown in FIG. 4, the amount of fuel passing through the left injection hole 831 is larger according to the difference in diameter between the injection holes 831 and 832.
It is larger than the amount of fuel passing through the injection hole 832 on the right side.
For this reason, at the immediately upstream portion of the orifice plate 83, the fuel flowing from the outer periphery of the needle 82 to the lower portion of the needle 82 does not flow toward the injection holes 831 and 832 in a well-balanced manner, and an unstable state of the fuel flow is likely to occur. Become. As a result, the injection state at the injection holes 831 and 832, especially the injection state at the large-diameter injection hole 831 becomes unstable, the spray direction fluctuates, and uniform fine spray cannot be obtained, which may deteriorate the exhaust emission. is there. Even if there is no difference between the diameters of the two types of injection holes, unless the injection holes are formed at equal intervals on a circle centered on the axis of the valve body,
Again, immediately upstream of the orifice plate, it does not flow evenly toward the injection holes, and the same problem occurs.

On the other hand, in the present fuel injection valve 1, the injection holes 501 and 502 are located symmetrically with respect to the axis C.
In addition, since all the injection holes 501 and 502 have the same diameter, the fuel flows immediately upstream of the orifice plate 5 toward each of the injection holes 501 and 502 in a symmetrical flow around the axis C. They do not form and become unstable. Thus, the injection state in each of the injection holes 501 and 502 is stabilized, and a uniform spray direction and uniform fine spray can be obtained.

It should be noted that the number of injection holes can be appropriately changed according to the required specification of the injection amount per unit time. Further, the injection holes may be formed not on one circle but on a plurality of circles. FIG. 3 shows such a modification, in which the IB-IB of FIG. 1 of the fuel injector having the configuration of FIG. 1 in which the orifice plate is replaced with another orifice plate.
2 shows a cross section corresponding to a cross section taken along the line. In the orifice plate 5A, injection holes 501 and 502 are formed on concentric circles A1 and A2 about the axis C, and the injection holes 501 and 502 on each of the circles A1 and A2 are formed at equal intervals.

On the inner circle A1, two open-side injection holes 501 are formed in the left half-circle, and two closed-side injection holes 502 are formed in the right half-circle. On the outer circle A2, four open injection holes 501 are formed in a 2/3 circle on the left side, and two open injection holes 502 are formed in a 1/3 circle on the right side. Thus, in the total of both circles A1 and A2, the number of injection holes in the open-side injection hole 501 is 6, and the number of injection holes in the closed-side injection hole 502 is 4
Becomes As described above, the number of the injection holes of the open-side injection holes and the number of the injection holes of the closed-side injection holes are each doubled while maintaining the ratio of the number of the injection holes to 3: 2 as in the case of the fuel injection valve 1 shown in FIG. The injection amount per hit can be increased.

The fuel injection valve according to this modification can be manufactured at low cost, and the fuel can flow symmetrically immediately upstream of the orifice plate 5A, and the injection state at the injection holes 501 and 502 can be stabilized.

Further, depending on the requirement for stabilizing the injection state, the injection holes need not necessarily be formed at equal intervals on a circle. In this case, too, the injection holes can be manufactured at low cost and can be distributed in two directions. Thus, a fuel injection valve having a well-balanced spray characteristic of the injected fuel can be obtained.

Further, the opening side injection holes and the closing side injection holes do not need to be formed completely in the same direction, and can be appropriately adjusted according to the required spray state and the like. .

The present invention can also be applied to an air-assist type fuel injection valve having an air-assist sleeve and colliding assist air with fuel injected from an injection hole to promote atomization of fuel. . In this case, as in the case of the fuel injection valve shown in FIG. 3, when the formation range of the open side injection hole 501 does not fall within the left half circle but enters the right half circle, the open injection hole 501 is not Of the injection fuel F1 of the closed side injection hole 5
Since the fuel is offset slightly to the right with respect to the injected fuel F2 from 02, the air assist sleeve forms a guide hole for guiding the injected fuel in the direction of each intake valve to the left, for example. It is desirable to adjust the shape.

[Brief description of the drawings]

FIG. 1A is an enlarged sectional view of a tip portion of a fuel injection valve of the present invention, and FIG. 1B is a sectional view taken along line IB-IB in FIG. 1A.

FIG. 2 is an overall sectional view of the fuel injection valve of the present invention.

FIG. 3 is a sectional view of a tip portion of another fuel injection valve of the present invention.

FIG. 4A is an enlarged cross-sectional view of a tip portion of one conventional fuel injection valve, and FIG. 4B is an IVB-IVB in FIG.
It is sectional drawing which follows a line.

[Explanation of symbols]

 Reference Signs List 1 fuel injection valve 1a fuel flow path 3 valve body 4 needle (valve element) 5,5A orifice plate 501,502 injection hole A, A1, A2 circle C axis

Claims (2)

[Claims] 1. A valve body which is opened and closed by a valve body at a downstream portion of a fuel flow path, a downstream end of the fuel flow path is closed by an orifice plate, and an injection hole is formed in the orifice plate at an acute angle with respect to the axial direction of the valve body. In a fuel injection valve, two types of injection holes are formed so as to face in two directions, and fuel is distributed and injected from the injection holes in the two directions so that the injection amount is non-uniform at a predetermined ratio. The ratio between the number of injection holes constituting the first type of injection holes and the number of injection holes forming the second type of injection holes was set to the above-mentioned predetermined ratio, and the diameters of all the injection holes were made the same. A fuel injection valve characterized in that: 2. The fuel injection valve according to claim 1, wherein said injection holes are formed at equal intervals on a circle centered on an axis of said valve body.