JP2001065425A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a seating shock by dropping the seating speed of a valve member while quickening the motion of the valve member at the valve closing time and reduce the operation sound at the seating time as well. SOLUTION: This nozzle needle 20 is energized toward a valve seat by the energizing force of a spring and a contact part 21 can be seated on the valve seat 16a. A slide part 22 formed on the fuel upper streamside of the contact part 21 is supported on the inner wall of a valve body 15 reciprocatably. A flange 24 formed in a flat annular shape between the contact part 21 and slide part 22 receives a force from the upper streamside of the flange 24 to the valve close direction by the fuel flowing to the lower streamside. The flow passage area of an annular clearance 60 formed between the flange 24 and the inner wall of the valve body 15 is set so as to become larger than the opening area formed between the contact part 21 and valve seat 16a when the nozzle needle 20 is lifted maximumly.

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 for reducing a seating shock generated when a valve is closed.

[0002]

2. Description of the Related Art In an electromagnetically driven fuel injection valve, for example, when energization of a coil included in an electromagnetic drive unit is turned on, a nozzle needle separates from a valve seat to inject fuel from an injection hole and energize the coil. Is turned off, the nozzle needle is seated on the valve seat by the urging force of the spring, whereby the injection hole is closed, and the fuel injection ends.

[0003]

However, when energization of the coil is turned off to stop fuel injection, noise generated by impact when the nozzle needle is seated on the valve seat is a problem. Japanese Unexamined Patent Application Publication No. 8-189439 discloses an attempt to suppress the secondary injection by lowering the descending speed of the nozzle needle when the valve is closed due to a fuel damper effect.
It is considered that the decrease in the descending speed of the nozzle needle can prevent the generation of sound when the valve is closed.

[0004] However, the fuel throttle passage which 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 decreases, and the opening formed by the nozzle needle and the valve seat and located downstream of the fuel throttle passage becomes a throttle. Therefore, the fuel throttle passage formed upstream of the opening formed between the nozzle needle and the valve seat between the outer peripheral surface of the movable core and the valve body reduces the descending speed of the nozzle needle when the valve is closed. It is unlikely that a sufficient damper effect will be obtained. 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 at the time of closing the valve, and thereby reducing the operating noise at the time of seating. To provide.

[0005]

According to the fuel injection valve of the present invention, a contact portion which can be seated on a valve seat and a sliding portion which is reciprocally supported by the valve body. The valve member has a fuel receiving portion that receives a force from the fuel flow in the valve closing direction and allows the fuel to flow 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 receiver from the fuel flow and the urging force of the urging means. Therefore, even when the urging force of the urging means is reduced, the moving speed in the valve closing direction can be secured at the initial stage of valve closing. Furthermore, when the valve member approaches the valve seat and the amount of fuel flowing out of 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 position is substantially the biasing force of the biasing means. Therefore, as the contact portion approaches the valve seat, the speed at which the valve member sits on the valve seat decreases, so that the impact exerted on the valve seat by the valve member is reduced.

[0006] According to the fuel injector of the third aspect of the present invention, the fuel receiving portion has a fuel through hole penetrating in the fuel flow direction. Therefore, by adjusting the diameter or the number of the fuel 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 flowing from the upstream side to the downstream side of the fuel receiving portion is reduced. Easy to adjust.

According to the fuel injection valve of the present invention, the fuel receiving portion has a concave portion formed toward the fuel upstream side. Since the force received from the fuel flow increases as compared with the case where the fuel flow is received by a flat plate, the moving speed of the valve member at the start of valve closing can be ensured even if the urging force of the urging means is reduced.

According to the fuel injection valve of the sixth or seventh aspect of the present invention, the volume of the fuel space defined by the partition portion, the inner peripheral surface, the valve seat surface having the valve seat, and the contact portion is as follows. As it moves in the direction in which it sits on the valve seat, the partition portion decreases as it approaches the valve seat surface. In other words, as the partition approaches the valve seat surface, the fuel in the fuel space is pushed out, and the fuel is discharged from the opening formed by the contact portion and the valve seat. Since the opening area decreases as the contact portion approaches the valve seat, the amount of fuel discharged from the opening decreases. Since the fuel in the fuel space is discharged from the opening formed between the contact portion and the valve seat by the partition portion descending together with the valve member, as the contact portion approaches the valve seat and the opening area decreases. , The decrease in the volume of the fuel space,
That is, the speed at which the valve member sits on the valve seat decreases. Therefore, with a simple configuration in which a partition portion that forms a minute gap with the inner peripheral surface of the valve body is provided on the valve member near the valve seat, the impact when the valve member is seated on the valve seat is reduced.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIGS. 1 and 2 show a fuel injection valve according to a first embodiment of the present invention. As shown in FIG. 2, a valve body 15, a nozzle needle 20 as a valve member, a movable core 30, a fixed core 31, a spring 32 as urging means, an adjuster are provided in a bottomed cylindrical member 11 of the fuel injection valve 10. The sting pipe 33 and the filter 34 are accommodated. The cylindrical member 11 includes a bottomed cylindrical portion 12, a non-magnetic cylindrical portion 13, and a magnetic cylindrical portion 14, and is arranged in this order from the lower fuel injection side in FIG. Spool 3 on the outer periphery of cylindrical member 11
5, a coil 36 wound around the coil 3 is provided.
6 and above, the resin mold 40 covers the upper part of the cylindrical member 11.

The bottomed cylindrical portion 12 of the cylindrical member 11 has a bottom 12a.
And a side portion 12b, and a through hole 12c is formed in the center of the bottom portion 12a. The through hole 12c communicates with the injection hole 18b formed in the injection hole plate 18 on the fuel downstream side of the injection hole 18b. The inner diameter of the non-magnetic cylinder 13 is the bottomed cylinder 1
The movable core 30 is slightly smaller than an inner diameter of the movable core 2 and is capable of reciprocating. A fuel inlet 14a is formed on the non-injection side of the magnetic cylinder portion 14, and a filter 34 for removing foreign matter in the fuel is mounted in the fuel inlet 14a.

As shown in FIG. 1, the valve body 15 is press-fitted into the bottomed cylinder portion 12, and the bottomed cylinder portion 12 and the valve body 15
A side portion 12b of the bottomed cylindrical portion 12 and an outer wall 15a of the valve body 15 in a state where the injection hole plate 18 is sandwiched in the axial direction.
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 whose diameter decreases toward the injection 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.

The injection hole plate 18 has a plate portion 18b formed in a thin plate shape, and the plate portion 18a is
2 is axially sandwiched between the bottom 12a of the second valve and the bottom outer wall 15c of the valve body 15. Injection hole 18b is plate part
Four are formed on the same circumference at the center of 8a. FIG.
The protective cap 19 made of resin shown in FIG. When the fuel injection valve 10 is attached to the intake pipe, the protective cap 19 is provided with the stopper of the intake pipe and the fuel injection valve 1.
This is for preventing 0 from coming into metallic contact.

The nozzle needle 20 is urged toward the valve seat 16a by the urging force of a spring 32, and the contact portion 21 formed at the tip of the nozzle needle 20 is
6a. The sliding portion 22 is formed on the fuel upstream side of the contact portion 21, that is, in the upper part of FIG. 2, and is supported by the inner wall of the valve body 15 so as to be able to reciprocate. The outer wall of the sliding portion 22 is chamfered to form a fuel passage between the outer wall and the inner peripheral wall of the valve body 15.

A joining portion 2 is further provided on the fuel upstream side of the sliding portion 22.
3 are formed. The nozzle needle 20 and the movable core 30 reciprocate integrally as a result of the joint portion 23 and the movable core 30 being laser-welded. The outer wall of the joint 23 is chamfered to form a fuel passage with the inner peripheral wall of the movable core 30.

As shown in FIG. 1, a flange 24 which is both a fuel receiving portion and a partition portion is formed between a contact portion 21 and a sliding portion 22 in a flat annular shape. Flange 24
May be formed integrally with the needle body by cutting or the like, or may be formed as a separate part 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 passage area of the clearance 60 is set so as to be larger than the opening area formed between the contact portion 21 and the valve seat 16a when the nozzle needle 20 is lifted to the maximum. In addition, flange 2
4. A fuel space 61 is formed by the valve seat surface 16, the inner peripheral surface 17, and the contact portion 21.

The filter 3 is connected through the fuel inlet 14a shown in FIG.
The fuel that has flowed in through the adjusting pipe 3
3 and the gap between the chamfered portion formed at the joint 23 of the nozzle needle 20 and the inner peripheral wall of the movable core 30, the circumferential wall of the valve body 15 and the sliding portion 22 of the nozzle needle 20. After passing through the gap with the four chamfered portions and the clearance 60, the nozzle needle 20 reaches the contact position between the contact portion 21 of the nozzle needle 20 and the valve seat 16a. The contact part 21 is the valve seat 16
a, the fuel injection from the injection hole 18b is shut off,
When the contact portion 21 is separated from the valve seat 16a, fuel is injected from the injection hole 18b.

The movable core 30 is made of a magnetic material and is formed in a cylindrical shape. The upper end surface of the movable core 30 is fixed core 31
Is provided so as to oppose the lower end surface of the base plate via 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 amount of press-fit of the adjusting pipe 33, the urging force of the spring 32 can be adjusted.
The adjusting pipe 33 may be screwed to the fixed core 31.

A spool 35 made of resin is mounted on the outer periphery of the cylindrical member 11, and a coil 36 is mounted on the outer periphery of the spool 35.
Is wound. A connector 40a is provided so as to protrude from the outer wall of the resin mold 40, and the coil 3
The terminal 41 electrically connected to the connector 6
0a. Spool 35 and coil 36
Constitutes an electromagnetic drive unit.

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 to the fixed core 31 side against the urging force of the spring 32, so that the nozzle needle 20 is lifted. As a result, when the contact portion 21 separates from the valve seat 16a, the injection hole 18b
The fuel is injected from.

(2) When the energization of the coil 36 is turned off, the force received from the spring 32 in the valve closing direction
The nozzle needle 20 is forced in the valve closing direction by the force received by the flange 24 when the rectified fuel passes through the fuel passage formed by the fuel cell 2 and the inner wall of the valve body 15 and collides with the flange 24 at a predetermined flow velocity V. Receive. 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 integrating the sum with the pressure receiving area of the flange 24. ρ is the density of the fuel. As described above, the nozzle needle 20 is urged downward in FIG. 2 by the urging force of the spring 32 and the force received by the flange 24 from the fuel flow, and the contact portion 21 is seated on the valve seat 16a. This allows
Fuel injection from the injection hole 18b is shut off.

Next, FIG. 3 shows the relationship between the passage of time and the lift amount of the nozzle needle in the first embodiment and the conventional examples 1 and 2 having no flange. In FIG.
The solid line is the first embodiment, the dotted line is the conventional example 1 without the flange and the spring of the same size as the conventional one, and the two-dot chain line is the conventional example without the flange and the spring with the smaller biasing force than the conventional one. Example 2 is shown.

In the first embodiment, when the power supply to the coil 36 is turned off, the valve closes at the same speed as the conventional example in the early stage of valve closing. And the contact part 21 of the nozzle needle 20 is the valve seat 1
When the area of the opening formed by the abutment portion 21 and the valve seat 16a decreases toward 6a, the pressure loss at the opening increases. Then, the pressure difference 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 that the descending speed of the nozzle needle 20 decreases.

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. 24 area), the amount of decrease in the volume of the fuel space 61 is reduced. Therefore, the descending speed of the flange 61, that is, the descending speed of the nozzle needle 20 decreases.

As a result, as compared with the prior art 1 having no flange 24, the abutment portion 21 has the valve seat 16
a, the contact portion 21 is moved to the valve seat 16.
The impact generated when sitting on a is reduced. Inner circumference 1
With a simple configuration in which the flange 24 forming the minute clearance 60 with the nozzle 7 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 spring is weakened without the flange 24, the impact exerted on the valve seat by the contact portion is small, but the fuel injected from when the coil is turned off to when the valve is closed. Since the amount is large, the emission amount of hydrocarbons (HC), carbon and the like increases.

(Second Embodiment, Third Embodiment) The second embodiment of the present invention
An embodiment and a third embodiment are shown in FIGS. 4 and 5, respectively. First
The same reference numerals are given to the same components as those in the embodiment, and the description is omitted. The flange 65, which is the fuel receiving portion and the partitioning portion of the second embodiment, and the flange 70, which is the fuel receiving portion and the partitioning portion of the third embodiment, have concave portions 66 and 71 formed toward the fuel upstream side, respectively. . The thickness of the flange 65 is greater at the outer peripheral edge 67 than at the recess 66, and the thickness of the flange 70 is uniform throughout. Compared to the flat flange 24 of the first embodiment, the fuel flow
The force received by 5, 70 increases. Therefore, the urging force of the spring for urging the nozzle needle in the valve closing direction can be reduced, and the impact at the time of closing the valve is reduced.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
Shown in The same reference numerals are given to the same components as those in the first embodiment, and the description is omitted. In the flange 75 which is the fuel receiving portion and the partition portion of the fourth embodiment, the outer peripheral edge corner on the fuel upstream side is formed in a curved shape. Therefore, when the nozzle needle 20 is lifted, the resistance that the flange 75, that is, the nozzle needle 20 receives, is reduced. Therefore, as shown by the two-dot chain line in FIG. 7, the lift speed of the nozzle needle 20 is increased and the valve opening responsiveness is increased as compared with the first embodiment.

Each of the flanges 24, 65, 70, and 75 of the first to fourth embodiments described above serves as both a fuel receiving portion and a partition portion. However, if only the function as the partition portion is satisfied, the clearance 60 between the inner peripheral surface 17 and the inner peripheral surface 17 is minutely set, so that the shape of the flange as the partition portion is not limited to the shape of each of the above embodiments. Is also possible. Further, if the sliding portion 22 is formed at a position close to the valve seat 16a, even if a flange is arranged on the upstream side of the sliding portion, the partitioning portion can be arranged near the valve seat. Can fulfill the function.

(Fifth Embodiment, Sixth Embodiment) The fifth embodiment of the present invention
An embodiment and a sixth embodiment are shown in FIGS. The same reference numerals are given to the same components as those in the first embodiment, and the description is omitted. Each of the flanges 24, 65 of the first to fourth embodiments,
70 and 75 are both a fuel receiving part and a partition part,
Each of the flanges 80 and 85 of the fifth and sixth embodiments has only a function as a fuel receiving portion.

The flange 80 of the fifth embodiment and the flange 85 of the sixth embodiment are formed in a flat annular shape. Then, fuel through holes 81, 86 penetrating through the flanges 80, 85
Are formed respectively. These fuel holes 81, 86
And the sum of the flow passage area of the clearance formed between the flanges 80 and 85 and the valve body is within a range in which the flanges 80 and 85 receive a sufficient force from the fuel flow in the valve closing direction. The opening area is set to be larger than the opening area formed between the contact portion and the valve seat when the nozzle needle is lifted up to the maximum. In the fifth embodiment and the sixth embodiment, the flow passage area of the clearance formed by the flanges 80 and 85 with the valve body is the same as the first embodiment, the second embodiment,
In the third and fourth embodiments, the flange is smaller than the flow passage area of the clearance 60 formed with the inner peripheral surface 17 of the valve body 15.

In the fifth and sixth embodiments, the fuel passage holes 8 are formed in the flat annular flanges 80 and 85.
Although the fuel injection holes 1 and 86 are formed, the fuel holes may be formed in the flanges 65 and 70 having the concave portions 66 and 71 shown in the second and third embodiments. In the fifth embodiment and the sixth embodiment, rather than adjusting the flow passage area with the clearance 60,
By changing the diameter or number of the fuel holes, the fuel flow rate can be easily adjusted.

In the above-mentioned plural embodiments showing the embodiment of the present invention, a flange for receiving a force in the valve closing direction from the fuel flow is formed between the contact portion of the nozzle needle and the sliding portion. I have. Thereby, the urging force of the spring for urging the nozzle needle in the valve closing direction can be reduced. Therefore, while the fuel injection amount is large in the early stage of closing the valve when the power supply to the coil is turned off, the nozzle needle moves in the valve closing direction at a sufficient speed by the urging force of the spring and the force received by the flange. Furthermore, since the force which the flange receives in the valve closing direction from the fuel flow in the late valve closing period when the contact portion approaches the valve seat and the fuel injection amount decreases, the impact exerted on the valve seat by the contact portion is reduced.

[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.

FIG. 3 is a characteristic diagram showing the relationship between the passage of time and the lift amount of a nozzle needle in the first embodiment, Conventional Example 1 and Conventional Example 2.

FIG. 4 is a sectional view showing a main part of a fuel injection valve according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a fuel injection valve according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a main part of a fuel injection valve according to a fourth embodiment of the present invention.

FIG. 7 is a characteristic diagram illustrating a relationship between a passage of time and a lift amount of a nozzle needle in the first embodiment, the fourth embodiment, and the conventional example 1.

FIG. 8 is a plan view showing a fuel receiver according to a fifth embodiment of the present invention.

FIG. 9 is a plan view showing a fuel receiver according to a sixth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 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 contact portion 22 sliding portion 24, 65, 70, 75 flange (fuel Receiving part,
Partition part) 60 Clearance 66, 71, Depression 80, 85 Flange (fuel receiving part) 81, 86 Fuel through hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02M 61/10 F02M 61/10 PL 61/16 61/16 X 61/18 350 61/18 350D // F16K 31/06 305 F16K 31/06 305Q

Claims (7)

[Claims] 1. A valve body having a valve seat, a contact portion that closes an injection hole by sitting on the valve seat, and opens the injection hole by separating from the valve seat, and the contact portion. A valve member having a sliding portion which is reciprocally supported by the valve body on the upstream side of the fuel and forms a fuel passage between the valve body and the valve body; and biases the valve member in a valve closing direction. And an electromagnetic drive unit that separates the contact portion from the valve seat against the urging force of the urging unit, wherein the valve member includes the fuel passage. A fuel receiving portion that receives a force in the valve closing direction from fuel flowing through the contact portion and the opening formed by the valve seat, wherein the fuel flows from an upstream side to a downstream side of the fuel receiving portion. Having a receiving portion between the contact portion and the sliding portion. Fuel injection valve that. 2. The fuel injection valve according to claim 1, wherein the fuel receiving portion forms a fuel passage between the fuel receiving portion and the valve body. 3. 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. 5. The fuel injection valve according to claim 1, wherein the fuel receiving portion has a recess formed toward a fuel upstream side. 6. A valve seat having a valve seat surface, a valve body having a cylindrical inner peripheral surface upstream of the valve seat surface, and an injection hole closed by sitting on the valve seat, thereby closing the valve seat. An abutting portion that opens the injection hole by taking off from the valve member, and a valve member having a sliding portion that slides on the inner peripheral surface; and an urging unit that urges the valve member in a valve closing direction. An electromagnetic drive unit that separates the contact portion from the valve seat against the biasing force of the biasing unit.The fuel injection valve, wherein the valve member is provided near the valve seat and A partition portion that forms a minute gap with a peripheral surface, the partition portion forms a fuel space with the inner peripheral surface, the valve seat surface and the contact portion, and the valve is disposed in a direction to be seated on the valve seat. A fuel injection valve, wherein the volume of the fuel space decreases as the member moves. 7. The fuel injection valve according to claim 6, wherein the valve seat surface has a conical shape whose diameter decreases toward an injection hole.