JP4123323B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve that reduces the impact of seating that occurs when the valve is closed.
[0002]
[Prior art]
For example, in an electromagnetically driven fuel injection valve, when energization of the coil of the electromagnetic drive unit is turned on, the nozzle needle is separated from the valve seat to inject fuel from the nozzle hole, and when energization of the coil is turned off, the spring When the nozzle needle is seated on the valve seat by the biasing force, the nozzle hole is closed, and fuel injection is completed.
[0003]
[Problems to be solved by the invention]
However, when energization of the coil is turned off and fuel injection is stopped, the noise generated by the impact when the nozzle needle is seated on the valve seat is a problem.
In Japanese Patent Laid-Open No. 8-189437, the lowering speed of the nozzle needle at the time of closing the valve is reduced by the damper effect of the fuel to suppress the secondary injection. It is considered that the generation of noise when the valve is closed can be prevented as a result of the lowering speed of the nozzle needle.
[0004]
However, the fuel throttle passage that provides this damper effect is formed between the outer peripheral surface of the movable core and the valve body on the upstream side of the seating portion of the nozzle needle. When the nozzle needle is seated on the valve seat, the opening area between the nozzle needle and the valve seat is reduced, and the nozzle needle and the valve seat are formed and the opening located downstream of the fuel throttle passage becomes the throttle. Therefore, the fuel throttle passage formed upstream of the opening formed between the outer peripheral surface of the movable core and the valve body and between the nozzle needle and the valve seat reduces the lowering speed of the nozzle needle when the valve is closed. It is unlikely that this will provide a sufficient damper effect.
An object of the present invention is to provide a fuel injection valve that can reduce the seating impact by reducing the seating speed of the valve member while speeding up the movement of the valve member when the valve is closed, thereby reducing the operating noise during the seating. It is to provide.
[0005]
According to the fuel injection valve of the first, second, or fourth aspect of the present invention, the fuel injection valve is closed from the fuel flow between the contact portion that can be seated on the valve seat and the sliding portion that is reciprocally supported by the valve body. The valve member has a fuel receiving portion that receives force in the valve direction and flows fuel from the upstream side to the downstream side. Therefore, the valve member is moved in the valve closing direction by the force received by the fuel receiving portion from the fuel flow and the urging force of the urging means. Therefore, even if the urging force of the urging means is reduced, the moving speed in the valve closing direction can be ensured in the initial stage of valve closing. Further, when the valve member approaches the valve seat and the amount of fuel flowing out from the opening formed between the contact portion of the valve member and the valve seat decreases, the force received by the fuel receiving portion from the fuel flow decreases, and the valve seat The force for moving the valve member toward the substantially becomes the urging force of the urging means. Accordingly, as the contact portion approaches the valve seat, the speed at which the valve member is seated on the valve seat is reduced, so that the impact of the valve member on the valve seat is reduced. The fuel receiving portion has a recess formed toward the fuel upstream side. Since the force received from the fuel flow is increased as compared with the case where the fuel flow is received by the flat plate, the moving speed of the valve member at the start of the valve closing can be secured even if the urging force of the urging means is reduced.
[0006]
According to the fuel injection valve of the third aspect of the present invention, the fuel receiving portion has the fuel through hole penetrating in the fuel flow direction. Therefore, by adjusting the diameter or number of the fuel passage holes, the urging force of the urging means is reduced to reduce the impact generated when the valve is closed, and the amount of fuel flow flowing from the upstream side to the downstream side of the fuel receiving portion is reduced. Easy to adjust.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First Reference Example)
1 and 2 show a fuel injection valve according to a first reference example of the present invention.
As shown in FIG. 2, in a bottomed cylindrical member 11 of the fuel injection valve 10, a valve body 15, a nozzle needle 20 as a valve member, a movable core 30, a fixed core 31, a spring 32 as an urging means, an adjuster A sting pipe 33 and a filter 34 are accommodated. The cylindrical member 11 includes a bottomed cylindrical portion 12, a nonmagnetic cylindrical portion 13, and a magnetic cylindrical portion 14, and is arranged in this order from the lower fuel injection side in FIG. A coil 36 wound around a spool 35 is disposed on the outer periphery of the cylindrical member 11, and the resin mold 40 covers the cylindrical member 11 from the coil 36.
[0010]
The bottomed cylindrical portion 12 of the cylindrical member 11 includes a bottom portion 12a and a side portion 12b, and a through hole 12c is formed at the center of the bottom portion 12a. The through hole 12c communicates with the nozzle hole 18b formed in the nozzle hole plate 18 on the fuel downstream side of the nozzle hole 18b. The inner diameter of the non-magnetic cylindrical portion 13 is slightly smaller than the inner diameter of the bottomed cylindrical portion 12, and supports the movable core 30 so as to be able to reciprocate. A fuel inlet 14a is formed on the non-injection side of the magnetic cylinder portion 14, and a filter 34 for removing foreign matters in the fuel is attached in the fuel inlet 14a.
[0011]
As shown in FIG. 1, the valve body 15 is press-fitted into the bottomed tube portion 12, and the bottomed tube is sandwiched between the bottomed tube portion 12 and the valve body 15 in the axial direction. The adjacent part of the side part 12b of the part 12 and the outer wall 15a of the valve body 15 is fixed at the welding position 50 by laser welding. The bottom inner wall of the valve body 15 has a conical valve seat surface 16 that is reduced in diameter toward the nozzle hole plate 18. A valve seat 16 a on which the contact portion 21 of the nozzle needle 20 can be seated is formed on the valve seat surface 16. The inner peripheral surface 17 is located on the fuel upstream side of the valve seat surface 16 and has a cylindrical shape.
[0012]
The nozzle hole plate 18 has a plate portion 18 b formed in a thin plate shape, and the plate portion 18 a is sandwiched in the axial direction between the bottom portion 12 a of the bottomed tube portion 12 and the bottom outer wall 15 c of the valve body 15. Four nozzle holes 18b are formed on the same circumference at the center of the plate portion 18a.
A resin protective cap 19 shown in FIG. 2 is press-fitted into the bottomed cylindrical portion 12. The protective cap 19 is for preventing the intake pipe stopper and the fuel injection valve 10 from coming into metal contact when the fuel injection valve 10 is attached to the intake pipe.
[0013]
The nozzle needle 20 is biased toward the valve seat 16a by the biasing force of the spring 32, and the contact portion 21 formed at the tip of the nozzle needle 20 can be seated on the valve seat 16a. The sliding portion 22 is formed on the fuel upstream side of the contact portion 21, that is, on the upper side in FIG. 2, and is supported on the inner wall of the valve body 15 so as to be reciprocally movable. The outer wall of the sliding portion 22 is chamfered to form a fuel passage between the outer peripheral wall and the inner peripheral wall of the valve body 15.
[0014]
A joint 23 is formed further upstream of the sliding portion 22 on the fuel side. Since the joint 23 and the movable core 30 are laser-welded, the nozzle needle 20 and the movable core 30 reciprocate integrally. The outer wall of the joint 23 is chamfered to form a fuel passage with the inner peripheral wall of the movable core 30.
[0015]
As shown in FIG. 1, the flange 24, which is a fuel receiving portion and a partition portion, is formed in a flat annular shape between the abutting portion 21 and the sliding portion 22. The flange 24 may be formed integrally with the needle body by cutting or the like, or may be formed separately from the needle body and connected by welding or the like. An annular clearance 60 through which fuel flows from the upstream side to the downstream side is formed between the flange 24 and the inner wall of the valve body 15. The flow path area of the clearance 60 is set to be larger than the opening area formed between the contact portion 21 and the valve seat 16a when the nozzle needle 20 is fully lifted. A fuel space 61 is formed by the flange 24, the valve seat surface 16, the inner peripheral surface 17, and the contact portion 21.
[0016]
The fuel flowing in through the filter 34 from the fuel inlet 14 a shown in FIG. 2 is a gap between the chamfered portion formed in the adjusting pipe 33 and the fixed core 31 and the joint 23 of the nozzle needle 20 and the inner peripheral wall of the movable core 30. The clearance between the circumferential wall of the valve body 15 and the four chamfered portion formed on the sliding portion 22 of the nozzle needle 20 and further through the clearance 60, the contact between the contact portion 21 of the nozzle needle 20 and the valve seat 16a. To the position. When the contact part 21 is seated on the valve seat 16a, the fuel injection from the nozzle hole 18b is cut off, and when the contact part 21 is separated from the valve seat 16a, the fuel is injected from the nozzle hole 18b.
[0017]
The movable core 30 is made of a magnetic material and formed in a cylindrical shape. The upper end surface of the movable core 30 is provided to face the lower end surface of the fixed core 31 with a predetermined gap. The fixed core 31 is made of a ferromagnetic material, and an adjusting pipe 33 is press-fitted and fixed to the inner wall. By adjusting the press-fitting amount of the adjusting pipe 33, the urging force of the spring 32 can be adjusted. A configuration in which the adjusting pipe 33 is screwed to the fixed core 31 may be employed.
[0018]
The resin spool 35 is attached to the outer periphery of the cylindrical member 11, and a coil 36 is wound around the outer periphery of the spool 35. A connector portion 40 a is provided so as to protrude from the outer wall of the resin mold 40, and a terminal 41 electrically connected to the coil 36 is embedded in the connector portion 40 a. The spool 35 and the coil 36 constitute an electromagnetic drive unit.
[0019]
Next, the operation of the fuel injection valve 10 will be described.
(1) When energization of the coil 36 is turned on, the movable core 30 is attracted toward the fixed core 31 against the biasing force of the spring 32, so that the nozzle needle 20 is lifted. As a result, when the contact portion 21 is separated from the valve seat 16a, fuel is injected from the nozzle hole 18b.
[0020]
(2) When the power supply to the coil 36 is turned off, in addition to the force received in the valve closing direction from the spring 32, the rectified fuel that passes through the fuel passage formed by the sliding portion 22 and the inner wall of the valve body 15 is predetermined. The nozzle needle 20 receives the force in the valve closing direction due to the force that the flange 24 receives by colliding with the flange 24 at the flow velocity V of V. Force flange 24 receives from the fuel flow, the flange 24 Seisa圧ΔP between the fuel upstream of the fuel downstream side, as well as pV ^2/2 is a dynamic pressure with the fuel flow passing through the periphery of the sliding portion 22 The sum is obtained by a value obtained by integrating the sum by the pressure receiving area of the flange 24. ρ is the density of the fuel. Thus, the nozzle needle 20 is biased downward in FIG. 2 by the biasing force of the spring 32 and the force that the flange 24 receives from the fuel flow, and the contact portion 21 is seated on the valve seat 16a. As a result, fuel injection from the nozzle hole 18b is blocked.
[0021]
Next, FIG. 3 shows the relationship between the passage of time and the lift amount of the nozzle needle in the first reference example, Conventional Example 1 and Conventional Example 2 having no flange. In FIG. 3, the solid line indicates the first reference example, the dotted line does not have a flange and the conventional example 1 has a spring having the same urging force as the conventional one, and the two-dot chain line does not have a flange and has a smaller urging force than the conventional one. The prior art example 2 which has a spring is shown.
[0022]
In the first reference example, when the energization to the coil 36 is turned off, the valve is closed at the same speed as the conventional example in the initial period of valve closing. When the contact portion 21 of the nozzle needle 20 approaches the valve seat 16a and the area of the opening formed by the contact portion 21 and the valve seat 16a decreases, the pressure loss at the opening increases. As a result, the differential pressure between the fuel upstream side and the fuel downstream side of the flange 24 decreases, and the force that the flange 24 receives from the fuel flow in the valve closing direction decreases, so the lowering speed of the nozzle needle 20 decreases.
[0023]
Further, when the flange 24 is lowered together with the nozzle needle 20, the fuel is pushed out from the fuel space 61, and the volume of the fuel space 61 is reduced. However, when the contact portion 21 approaches the valve seat 16a and the area of the opening formed by the contact portion 21 and the valve seat 16a decreases, the amount of fuel discharged from the opening decreases. The volume reduction amount of the fuel space 61 represented by (area of 24) is reduced. Therefore, the descending speed of the flange 61, that is, the descending speed of the nozzle needle 20 is decreased.
[0024]
As a result, the speed at which the contact portion 21 heads toward the valve seat 16a is reduced in the later stage of closing the valve as compared with the conventional example 1 that does not have the flange 24, and thus occurs when the contact portion 21 is seated on the valve seat 16a. Impact is reduced. With a simple configuration in which the flange 24 that forms the minute clearance 60 with the inner peripheral surface 17 is provided on the nozzle needle 20, it is possible to reduce the impact when the nozzle needle 20 is seated when the valve is closed.
In the conventional example 2 in which the urging force of the spring is weakened without the flange 24, the impact exerted on the valve seat by the contact portion is reduced, but the fuel injected from when the coil is turned off to when the valve is closed Since the amount is large, emissions of hydrocarbons (HC) and carbon increase.
[0025]
(First embodiment, second embodiment)
A first embodiment and a second embodiment of the present invention are shown in FIGS. 4 and 5, respectively. Components that are substantially the same as those of the first reference example are denoted by the same reference numerals, and description thereof is omitted.
Flange 70, which is also the first is a fuel receiving unit of the fuel receiving portion a and the flange 65 and the second embodiment is also the partition portion of Example partitioning portion each recess 66 and 71 toward the fuel upstream side is formed . As for the thickness of the flange 65, the outer peripheral edge 67 is thicker than the recess 66, and the thickness of the flange 70 is uniform throughout. Compared with the flat flange 24 of the first reference example, the force received by the flanges 65 and 70 from the fuel flow is increased. Therefore, since the urging force of the spring that urges the nozzle needle in the valve closing direction can be reduced, the impact at the time of valve closing is reduced.
[0026]
( Second reference example)
A second reference example of the present invention is shown in FIG. Components that are substantially the same as those of the first reference example are denoted by the same reference numerals, and description thereof is omitted.
The flange 75, which is the fuel receiving portion and the partitioning portion of the second reference example, has an outer peripheral corner portion on the upstream side of the fuel formed into a protruding curved surface. Therefore, the resistance that the flange 75, that is, the nozzle needle 20 receives when the nozzle needle 20 lifts is reduced. Therefore, as shown by a two-dot chain line in FIG. 7, the lift speed of the nozzle needle 20 is increased as compared with the first reference example, and the valve opening response is increased.
[0027]
The flanges 24, 65, 70, and 75 of the first and second embodiments and the first and second reference examples described above also serve as a fuel receiving portion and a partitioning portion. However, if only the function as the partition portion is satisfied, by setting the clearance 60 with the inner peripheral surface 17 to be minute, the shape of the flange as the partition portion is not limited to the shape of each of the above embodiments and reference examples. It is also possible to make it. Further, if the sliding portion 22 is formed at a position close to the valve seat 16a, the partition portion can be disposed near the valve seat even if a flange is disposed on the upstream side of the sliding portion. Can fulfill the function.
[0028]
( 3rd Example, 4th Example)
A third embodiment and a fourth embodiment of the present invention are shown in FIGS. Components that are substantially the same as those of the first reference example are denoted by the same reference numerals, and description thereof is omitted. The flanges 24, 65, 70 and 75 of the first and second embodiments and the first and second reference examples serve as both the fuel receiving portion and the partition portion, but the flanges of the third and fourth embodiments. 80 and 85 have only a function as a fuel receiving portion.
[0029]
The flange 80 of the third embodiment and the flange 85 of the fourth embodiment are formed in a flat annular shape. Fuel passage holes 81 and 86 penetrating the flanges 80 and 85 are formed, respectively. The sum of the flow passage areas of these fuel through holes 81 and 86 and the flow passage area of the clearance formed between the flanges 80 and 85 and the valve body is such that the flanges 80 and 85 close a sufficient force from the fuel flow. Within the range received in the direction, it is set to be larger than the opening area formed between the contact portion and the valve seat when the nozzle needle is lifted to the maximum. In the third and fourth embodiments, the flow path area of the clearance formed by the flanges 80 and 85 with the valve body is the same as that in the first embodiment, the second embodiment, the first reference example, and the second reference example. It becomes smaller than the flow path area of the inner peripheral surface 17 of the body 15 and the clearance 60 formed.
[0030]
In the third embodiment and the fourth embodiment, the fuel through holes 81 and 86 are formed in the flanges 80 and 85 formed in a flat annular shape, but the recess 66 shown in the first and second embodiments, A fuel through hole may be formed in the flanges 65 and 70 having 71.
In the third and fourth embodiments, the flow rate of the fuel can be easily adjusted by changing the diameter or number of the fuel through holes, rather than adjusting the flow passage area with the clearance 60.
[0031]
In the above-described plurality of examples showing the embodiment of the present invention described above, a flange that receives a force in the valve closing direction from the fuel flow is formed between the contact portion and the sliding portion of the nozzle needle. Thereby, the urging force of the spring that urges the nozzle needle in the valve closing direction can be reduced. Therefore, while the amount of fuel injection is large at the initial valve closing time when the coil is de-energized, the nozzle needle moves in the valve closing direction at a sufficient speed due to the biasing force of the spring and the force received by the flange. Further, since the force that the flange receives from the fuel flow in the valve closing direction becomes smaller in the latter valve closing period when the contact portion approaches the valve seat and the fuel injection amount decreases, the impact of the contact portion on the valve seat is reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a fuel injection valve according to a first reference example of the present invention.
FIG. 2 is a cross-sectional view showing a fuel injection valve according to a first reference example.
FIG. 3 is a characteristic diagram showing the relationship between the passage of time and the lift amount of the nozzle needle in the first reference example, the conventional example 1 and the conventional example 2;
FIG. 4 is a cross-sectional view showing the main part of the fuel injection valve according to the first embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a main part of a fuel injection valve according to a second embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a main part of a fuel injection valve according to a second reference example of the present invention.
7 is a characteristic diagram showing the relationship between the passage of time and the lift amount of the nozzle needle in the first reference example, the second reference example, and the conventional example 1. FIG.
FIG. 8 is a plan view showing a fuel receiving part according to a third embodiment of the present invention.
FIG. 9 is a plan view showing a fuel receiving portion according to a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Fuel injection valve 15 Valve body 16 Valve seat surface 16a Valve seat 17 Inner peripheral surface 18 Injection hole plate 18b Injection hole 20 Nozzle needle (valve member)
21 Abutting part 22 Sliding part 24, 65, 70, 75 Flange (fuel receiving part, partition part)
60 Clearance 66, 71 Concave 80, 85 Flange (fuel receiving part)
81, 86 Fuel hole

Claims (4)

A valve body having a valve seat;
A contact portion that closes the nozzle hole by being seated on the valve seat and opens the nozzle hole by being separated from the valve seat, and a reciprocating movement to the valve body on the fuel upstream side of the contact portion A valve member having a sliding portion supported and forming a fuel passage between the valve body;
Biasing means for biasing the valve member in the valve closing direction;
An electromagnetic drive part that separates the abutting part from the valve seat against the urging force of the urging means;
A fuel injection valve comprising:
The valve member is a fuel receiving portion that receives a force in a valve closing direction from fuel that passes through the fuel passage and flows toward an opening formed by the contact portion and the valve seat, and is upstream of the fuel receiving portion. the fuel receiving portion through which fuel flows possess between the sliding portion and the contact portion downstream from,
Fuel injection valve the fuel receiving portion, characterized in that the have a recess formed towards the fuel upstream side.   The fuel injection valve according to claim 1, wherein the fuel receiving portion forms a fuel passage between the valve body and the fuel receiving portion.   The fuel injection valve according to claim 1, wherein the fuel receiving portion has a fuel through hole penetrating in a fuel flow direction.   4. The fuel injection valve according to claim 1, wherein the fuel receiving portion is formed in a flange shape.

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