CN114616389A

CN114616389A - Fuel injection valve

Info

Publication number: CN114616389A
Application number: CN201980101637.0A
Authority: CN
Inventors: 长村太树; 福冨范久; 宗实毅; 平井学
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2022-06-10
Also published as: JPWO2021090388A1; WO2021090388A1

Abstract

A fuel injection valve (100) comprising: a solenoid device (2) generating a magnetic attraction force; a core (3) made of a tubular magnetic body at least partially surrounded by the solenoid device (2); a spring (4) provided on the inner peripheral portion of the core (3); a tubular holder (5) provided at the lower end of the core (3); a needle member (6) which is disposed inside the holder (5) and which includes an armature (61) made of a magnetic material, a tube (62) coupled to the armature (61), and a valve portion (63) coupled to the tube (62); and a valve seat (7) that abuts the valve section (63). The needle (6) is guided by the sliding portion (61a) of the armature (61) and the sliding portion (63a) of the valve portion (63) and moves in the axial direction of the tube (62), and the tube (62) has: extending over the entire axial length from the upper end to the lower end; and a through hole (9) opposed to the slit (9s) and extending in the axial direction.

Description

Fuel injection valve

Technical Field

The present application relates to a fuel injection valve.

Background

Conventionally, as disclosed in, for example, patent document 1, a fuel injection valve is known which includes a needle (described as a needle in patent document 1) movable in an axial direction, the needle being formed of a movable element, a valve closing element, and a coupling member, so-called a tube, coupling the movable element and the valve closing element.

The fuel injection valve disclosed in patent document 1 is provided with a slit that is long in the longitudinal direction and is formed such that the opening width of the end portion on the valve closing body side is smaller than the opening width of the central portion. Further, the movable element and the pipe, and the valve closing element and the joint member are joined by welds, respectively.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2001-504917

Disclosure of Invention

Technical problems to be solved by the invention

In general, in a fuel injection valve, by repeating energization and energization stop, the needle is repeatedly moved up and down in the axial direction, and the valve portion is opened and closed to inject fuel. The range of the axial movement of the needle is limited to the upstream side of the fuel flow path by the core and the downstream side by the valve seat provided on the downstream side. An impact is applied to the abutment when the needle abuts the core or the valve seat.

In the fuel injection valve disclosed in patent document 1, although a slit that is long in the longitudinal direction is provided in a tubular pipe, only one slit that is long in the longitudinal direction is provided, and therefore, when the needle comes into contact with the core and the valve seat, the pipe is compressed and deformed while being bent. When the tube is compressed, the bending stress is maximized at the intermediate portion and the tube is displaced radially outward, and the entire tube becomes a barrel shape.

The needle is guided by the two sliding portions at the upper and lower positions to perform the reciprocating operation, but if the gap of the sliding portion is small and the above-described bending occurs when the valve portion is opened and closed, the outer peripheral portion of the needle interferes with the sliding portion on the opposite side, and a large amount of abrasion occurs on both sides. Due to the wear, for example, a change in injection amount due to long-term use of an installed engine occurs, and this may cause an engine failure.

The present application discloses a technique for solving the above-described problem, and an object thereof is to provide a fuel injection valve in which the needle is prevented from being bent when a valve portion is opened and closed, and wear of a sliding portion is reduced.

Technical scheme for solving technical problems

The fuel injection valve disclosed in the present application is characterized by comprising: a solenoid device that generates magnetic attraction force; a core constituted by a tubular magnetic body at least partially surrounded by the solenoid device; a spring provided at an inner peripheral portion of the core; a tubular holder provided at a lower end portion of the core; a needle disposed inside the holder and including an armature made of a magnetic material, a tube coupled to the armature, and a valve portion coupled to the tube; and a valve seat that abuts against the valve portion, the needle being guided by the sliding portions of the armature and the valve portion to move in the axial direction of the tube, the tube having: a slit extending over an entire axial length from an upper end portion to a lower end portion in the axial direction; and a through hole opposed to the slit and extending in the axial direction.

Effects of the invention

According to the fuel injection valve of the present application, it is possible to obtain a fuel injection valve in which the needle is prevented from being bent when the valve portion is opened and closed, and the abrasion of the sliding portion is reduced.

Drawings

Fig. 1 is a sectional view of a fuel injection valve according to embodiment 1.

Fig. 2 is an enlarged view of a portion a of the fuel injection valve of fig. 1.

Fig. 3 is a view showing a state before rolling of a pipe constituting the fuel injection valve shown in fig. 1.

Fig. 4 is a cross-sectional view of the rolled pipe as viewed from the direction of line B-B in fig. 3.

Fig. 5 is a diagram showing a state before rolling of a pipe constituting a fuel injection valve according to embodiment 2.

Fig. 6 is a diagram showing a state before rolling of a pipe constituting a fuel injection valve according to embodiment 3.

Fig. 7 is a diagram showing a state in which the pipe is bent and deformed when the fuel injection valve of embodiment 3 is opened.

Fig. 8 is a diagram showing a state before rolling of a pipe constituting a fuel injection valve according to embodiment 4.

Fig. 9 is a diagram showing a state before rolling of a pipe constituting a fuel injection valve according to embodiment 5.

Detailed Description

Hereinafter, preferred embodiments of the fuel injection valve according to the present invention will be described with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals, and the dimensions and the scaling ratios of the corresponding components are independent of each other. The structure of the fuel injection valve actually includes a plurality of members, and for the sake of simplifying the description, only the portions necessary for the description are described, and the other portions are omitted.

Embodiment mode 1

Fig. 1 is a cross-sectional view of a fuel injection valve according to embodiment 1, and fig. 2 is an enlarged view of a portion a of fig. 1.

In fig. 1 and 2, a fuel injection valve 100 supplies fuel to an internal combustion engine used as an engine of, for example, an automobile. The fuel injection valve 100 includes: a solenoid device 2, the solenoid device 2 generating magnetic attraction force by supplying current from the drive circuit 1; a core 3, the core 3 being composed of a tubular magnetic body at least partially surrounded by the solenoid device 2; a spring 4, the spring 4 being provided on an inner peripheral portion of the core 3; a tubular holder 5 provided at a lower end portion of the core portion 3, an end portion of the holder 5 being inserted between a lower end portion of an inner peripheral portion of the spiral pipe device 2 and a lower end portion of an outer peripheral portion of the core portion 3; a needle 6, the needle 6 being disposed inside the holder 5; a valve seat 7; and a plate 8, the plate 8 being combined with the valve seat 7. The needle member 6 is formed of an armature 61, a tube 62, and a valve portion 63, the armature 61 being made of a magnetic body, the tube 62 being coupled to the armature 61, and the valve portion 63 being coupled to the tube 62. That is, the tube 62 is a coupling member of the armature 61 and the valve portion 63, and the valve portion 63 abuts against the valve seat 7.

The armature 61 and the tube 62 are joined by, for example, welding after the tube 62 is press-fitted to the armature 61, and the valve portion 63 is welded to, for example, the tube 62. Further, the core 3 is, for example, welded to the holder 5 after being pressed into the holder 5. The valve seat 7 is joined to a plate-like member 8 located on the downstream side of the valve seat 7, i.e., on the downstream side of the fuel flow path, and the plate-like member 8 and the holder 5 are welded together, for example. With the above structure, the valve seat 7 is fixed to the holder 5.

Next, the operation of the needle 6 in the fuel injection valve 100 configured as described above will be described.

When the solenoid device 2 is energized from the drive circuit 1 and a magnetic field is generated in the solenoid device 2, an electromagnetic force acts on the armature 61 to attract the needle 6 toward the core 3. Thereby, the needle 6 is guided by the sliding portion 61a of the armature 61 and the sliding portion 63a of the valve portion 63 to move in the axial direction. In the present embodiment, the outer peripheral portion of the armature 61 facing the inner peripheral portion 5a of the holder 5 serves as a sliding portion 61a of the armature 61. An outer peripheral portion of the valve portion 63 facing the inner peripheral portion 7a of the valve seat 7 serves as a sliding portion 63a of the valve portion 63. The movable limit of the needle 6 in the axial direction toward the core 3 is a position where the armature 61 abuts against the core 3.

After the energization to the solenoid device 2 is stopped, the needle 6 is guided by the sliding portion 63a of the valve portion 63 and the sliding portion 61 of the armature 61 by the elastic force of the spring 4 provided inside the core 3 to move in the axial direction. The limit of the axial movement of the valve element 6 in the direction away from the core 3 is the position at which the valve portion 63 is seated on the valve seat 7.

Fig. 3 is a diagram showing a state before rolling of the pipe 62 constituting the fuel injection valve 100, and fig. 4 is a cross-sectional view of the pipe 62 after rolling as viewed from the direction of line B-B in fig. 3.

As shown in fig. 3 and 4, the tube 62 is produced by rolling a thin flat plate 62a having a rectangular shape and being long in the lateral direction. The flat plate portion 62a is made of a rolled plate of stainless steel having a thickness of about 0.5 mm. A through hole 9 elongated in the direction of extension of the center line is formed in the center line of the flat plate 62a by press working. The center line C of the through hole 9 coincides with the center line of the flat plate 62 a.

The through hole 9 opens with a space a between the upper end portion in the axial direction and the upper surface of the flat plate 62a, and with a space b (b ≈ 1mm) between the lower surface of the flat plate 62 a. The through hole 9 has a width d (d ≈ 0.3mm) and is elongated in the center line C direction, and an upper end portion in the axis line direction and a lower end portion in the axis line direction are formed in curved shapes R, respectively. The flat plate 62a is roll-processed in fig. 3 until the left end face and the right end face, which face each other with the slit 9s therebetween, approach each other, and becomes a tube 62 having a C-shaped cross section. That is, the tube 62 is formed with a slit 9s extending over the entire axial length from the upper end portion in the axial direction to the lower end portion in the axial direction, and the tube 62 has a width d on the inner diameter side.

The axial upper end of the tube 62 is press-fitted into the armature 61. The press-fitting is performed with a press-fitting length a-b until the distance between the lower end portion α of the armature 61 and the upper end portion of the through hole 9 in the axial direction is b. After press-fitting, the tube 62 and the lower end portion α of the armature 61 are joined together by, for example, welding. Next, the valve portion 63 is brought into contact with and held by the axial lower end portion of the tube 62, and the valve portion 63 is joined to the axial lower end portion of the tube 62 by, for example, welding. The upper and lower welded portions of the tube 62 have a distance b from the upper and lower axial ends of the through hole 9, and the distance b is set to a length about 2 times the thickness of the tube 62. Therefore, deformation due to press working of the through hole 9 can be suppressed at the welded portions above and below the tube 62, and even if the flat plate 62a is in a tube-like state after rolling, good roundness can be obtained, and high-strength welding can be achieved while maintaining a contact state with the armature 61 and the valve portion 63 over the entire circumference.

The fuel injection valve 100 according to embodiment 1 is configured as described above, and when the fuel injection valve 100 having the needle 6 is energized, the upper end surface of the armature 61 of the needle 6 collides with the lower end surface of the core 3, and the valve is opened. The needle 6 is composed of an armature 61 and a valve portion 63 having high rigidity and high mass, and a tube 62 having low rigidity and low mass, and is mechanically configured as a so-called spring-mass system in which the armature 61 and the valve portion 63 as mass points are connected to the upper and lower sides of the tube 62 as a spring. The movement amount mv of the needle 6 at the time of valve-opening collision (a physical amount obtained by multiplying the velocity v by the mass m) is converted into an impulse Ft (a physical amount obtained by multiplying the reaction force F received from the core 3 by the time t during which the reaction force F is received) received by the end surface of the armature 61, and the needle 6 is stationary. Since the amount of movement of the valve portion 63 is transmitted to the armature 61 with a delay due to the deformation of the tube 62, the time t becomes long and the repulsive force becomes small. When the repulsive force is weakened to suppress the abrasion of the armature 61, the rigidity of the tube 62 may be reduced.

At the time of a valve opening collision, the tube 62 receives the movement amount of the valve portion 63 and has a compressive load applied from the lower end portion in the axial direction. The cylindrical thin portion of the tube 62 that receives the compressive load expands in diameter toward the outer peripheral portion side, and the intermediate portion that has the highest bending stress becomes the most displaced in the radially outer direction, and therefore, deforms into a barrel shape.

The expanded diameter of the intermediate portion of the tube 62 is maximized at the slit 9s without circumferential restraint, but is expanded in the portion of the through hole 9, so that the tube 62 is expanded in diameter with high balance and compressed with high balance according to the expanded diameter, so that the tube 62 can be in a state in which the bending is also suppressed, and contributes to suppressing the wear of the sliding portion at the time of valve opening. In addition, although the above description has been given for the case of opening the valve, the same applies to the case of closing the valve.

Embodiment mode 2

Next, the fuel injection valve of embodiment 2 will be explained.

In fig. 5, in the flat plate 62 constituting the tube 62, in addition to the through-hole 9, there is one second through-hole 9a on each of both sides of the through-hole 9. The second through holes 9a are formed on both sides of the through hole 9 in left-right symmetry with respect to the axial direction of the through hole 9. The second through hole 9a is formed at a position intermediate between the slit 9s (see fig. 4) of the C-shaped pipe 62 and the through hole 9, and is extended in the same direction as the axial direction of the through hole 9 by a width d (d ≈ 0.3mm), and the upper end portion in the axial direction and the lower end portion in the axial direction are formed in a curved shape R. Since other configurations are the same as those in embodiment 1, the illustration thereof is omitted.

According to the fuel injection valve of embodiment 2 configured as described above, the pipe 62 receives the movement amount of the valve portion 63 at the time of valve opening collision and a compression load acts on the lower end portion in the axial direction. The thin cylindrical portion of the tube 62 subjected to the compressive load is expanded in diameter toward the outer peripheral portion side, and the intermediate portion having the highest bending stress is deformed into a barrel shape because it is maximally displaced in the radially outer direction.

The expanded diameter of the intermediate portion of the tube 62 is largest at the slit 9s having no circumferential constraint, but is expanded in the portion of the through-hole 9 on the opposite side to the slit 9s without circumferential constraint, and therefore, the expanded diameter is expanded in a right-and-left highly balanced manner, and is compressed in a highly balanced manner according to the expanded diameter. Therefore, as compared with the case where the second through hole 9a is not provided, the bending of the pipe 62 is suppressed, and the second through hole 9a is formed to increase the bending deformation of the pipe 62, so that the rigidity is lowered, and the abrasion of the collision portion at the time of opening and closing the valve is suppressed.

Embodiment 3

Next, the fuel injection valve of embodiment 3 will be explained.

In fig. 6, in the flat plate 62a constituting the tube 62, in addition to the through hole 9, there is provided a third through hole 11a having an axis orthogonal to the axis of the through hole 9 and long in a lateral direction intersecting the through hole 9. Further, second slits 11b are formed on both right and left end sides of the third through hole 11a, and the second slits 11b are laterally long with a gap from the third through hole 11a, that is, have the same axis as that of the third through hole 11 a. The second slits 11b are open to the left and right end surfaces of the flat plate 62a, i.e., the slits 9s, respectively. Further, a fourth through hole 11c is formed above the third through hole 11a and the second slit 11b, the fourth through hole 11c is formed with a gap from the through hole 9, is bilaterally symmetrical with respect to the through hole 9, is long in the lateral direction, and the fourth through hole 11c has an axis orthogonal to the axis of the through hole 9.

Here, the first layer is constituted by two fourth through holes 11c, and the second layer is constituted by the third through holes 11a and two second slits 11 b. The width e of the third through hole 11a, the two second slits 11b, and the two fourth through holes 11c is formed to e ≈ 0.4 mm. Further, the interval f between the first layer and the second layer is formed to be f ≈ 0.8 mm. Further, the through hole 9 is opened from the first layer to the second layer. Since other configurations are the same as those in embodiment 1 or embodiment 2, the illustration thereof is omitted.

According to the fuel injection valve of embodiment 3 configured as described above, the pipe 62 receives the movement amount of the valve portion 63 at the time of valve opening collision and a compression load acts on the lower end portion in the axial direction. As shown in fig. 7 (a) and (b), the load applied to the downstream side of the pipe 62 is applied to the central portion of the wall 12a formed between the first layer and the second layer via the wall 12b formed between the third through hole 11a and the second slit 11b forming the second layer.

Since the two end portions of the wall portion 12a are supported by the two wall portions of the first layer and are in a state of receiving a load at the center of the cantilever beam, they are bent and deformed, and the rigidity is lowered, which contributes to suppressing wear of the collision portion at the time of opening and closing the valve.

The elements of the left and right double cantilever beams (rotation ち beams) are arranged in an independent state in which the slits 9s and the through holes 9 are adjacent to each other on both sides thereof and no lateral constraint is imposed, and deformation in the lateral direction when a compressive load is applied is not constrained, so that the amount of deformation increases and the left and right balance is good.

Embodiment 4

Next, the fuel injection valve of embodiment 4 will be explained.

In fig. 8, in addition to the through hole 9, a third through hole 11a and a second slit 11b that is laterally long with a gap between both right and left end sides of the third through hole 11a and the third through hole 11a are formed in the flat plate 62a that constitutes the tube 62. A fifth through hole 11d and a third slit 11e are formed in the center portion of the axial direction end side of the through hole 9, the fifth through hole 11d being long in the lateral direction, the third slit 11e being long in the lateral direction with a space between both sides of the fifth through hole 11d and the fifth through hole 11 d. The first layer is constituted by the fifth through hole 11d and the third slit 11 e. A second layer is formed below the first layer with a space f, and the second layer is bilaterally symmetric with respect to the through-hole 9 and is formed of a laterally long fourth through-hole 11c with a gap with the through-hole 9.

A third layer is formed below the second layer, and the third layer is formed by the third through holes 11a and the second slits 11b, has a distance f from the first layer, and has the same form as the first layer. Further, the widths e of the fifth through hole 11d and the two third slits 11e forming the first layer, the two fourth through holes 11c forming the second layer, and the third through hole 11a and the two second slits 11b forming the third layer are formed to e ≈ 0.4 mm. Further, the interval f between the first layer and the second layer and the interval f between the second layer and the third layer are formed to f ≈ 0.8 mm. In addition, the through hole 9 is opened from the first layer to the second layer. Since other configurations are the same as those in embodiment 1, embodiment 2, or embodiment 3, the illustration thereof is omitted.

According to the fuel injection valve of embodiment 4 configured as described above, the pipe 62 receives the movement amount of the valve portion 63 at the time of valve opening collision and a compression load acts on the lower end portion in the axial direction. The load applied to the downstream side of the pipe 62 is applied to the central portion of the wall portion 12a formed between the second layer and the third layer via the wall portion 12b formed between the third through hole 11a and the second slit 11b constituting the third layer.

Both ends of the wall portion 12a are supported by the two wall portions of the second layer, and are in a state of receiving a load at the center of the double suspension arm. The wall 12b of the third layer is connected to both ends of the wall 12c formed between the first and second layers, and the wall 12c is supported by the wall of the first layer, and is in a state of being at the center of the load-receiving suspension arm. Therefore, the two double cantilever beams are arranged in series, and the deformation is increased and the rigidity is further lowered as compared with embodiment 3, which contributes to suppressing the wear of the collision portion at the time of opening and closing the valve.

The elements of the two left and right double cantilevers arranged in series are arranged in an independent state in which the slit 9s and the through hole 9 are adjacent to each other on both sides thereof and no lateral restraint is applied, and deformation in the lateral direction when a compressive load is applied is not restrained, and therefore, the amount of deformation is increased and the left and right balance is good.

Embodiment 5

Next, a fuel injection valve according to embodiment 5 will be described.

In fig. 9, in the flat plate 62a constituting the tube 62, the through hole 9 is formed in such a length that the position of the upper end portion in the axial direction of the through hole 9 is the welded portion between the armature 61 and the tube 62, that is, the lower end portion α of the armature 61 is located closer to the core 3 than the lower end portion α of the armature 61, and the lower end portion α of the armature 61 as the welded portion crosses. The other structures are the same as those in embodiment 1, and therefore, the illustration thereof is omitted.

The fuel injection valve according to embodiment 5 is configured as described above, and the armature 61 and the pipe 62 are joined together by laser welding a welded portion between the lower end portion of the armature 61 and the pipe 62. The welded portion irradiated with the spot-like laser beam melts and mixes the two metals, but after the laser beam irradiation is completed, the armature 61 is contracted by solidification and cooling, and is pulled by the welded portion to be bent and deformed. The laser irradiation is rotated once on the circumference of the boundary portion of the both by the rotation of the needle 6 to complete the full-circumference welding.

The bending deformation occurs at each portion of the spot-shaped welded portion, but the same deformation occurs on the opposite side of the shaft by the full-circle welding, and as a result, the bending deformation of the armature 61 is also suppressed.

In the present embodiment, the slit 9s is formed in the tube 62, and the through hole 9 is formed on the opposite side of the central axis of the tube 62 with the slit 9s interposed therebetween, and therefore, the armature 61 and the tube 62 are welded at the uniform portions except for the slit 9s and the through hole 9, and therefore, the bending deformation of the tube 62 can be prevented, and the needle 6 with less bending can be obtained. This suppresses wear of the sliding portion due to the sliding operation, and prevents a change in the flow rate due to long-term use.

While various exemplary embodiments and examples have been described in the present application, various features, modes, and functions described in one or more embodiments are not limited to the application to specific embodiments, and can be applied to the embodiments alone or in various combinations.

Therefore, countless modifications not illustrated are assumed to be within the technical scope disclosed in the present application. For example, the present invention includes a case where at least one component is modified, added, or omitted, and also includes a case where at least one component is extracted and combined with a component of another embodiment.

(symbol description)

1a drive circuit; 2a solenoid device; 3a core part; 4, a spring; 5a holder; 5a inner peripheral portion; 6, a needle-shaped member; 61 an armature; 61a sliding part; 62 tubes; 62a flat plate; a valve section 63; 63a sliding part; 7, valve seats; 7a inner peripheral portion; 8 a plate-like member; 9 through holes; 9a second via hole; a 9s slit; 11a third through hole; 11b a second slit; 11c a fourth through-hole; 11d a fifth through hole; 11e a third slit; 12a, 12b, 12c wall portions; 100 a fuel injection valve; an R curve shape; alpha lower end.

Claims

1. A fuel injection valve characterized by comprising:

a solenoid device that generates magnetic attraction force;

a core constituted by a tubular magnetic body at least partially surrounded by the solenoid device;

a spring provided at an inner peripheral portion of the core;

a tubular holder provided at a lower end portion of the core;

a needle disposed inside the holder and including an armature made of a magnetic material, a tube coupled to the armature, and a valve portion coupled to the tube; and

a valve seat abutting against the valve portion,

the needle is guided by the sliding portions of the armature and the valve portion to move in the axial direction of the tube,

the tube has: a slit extending over an entire axial length from an upper end portion to a lower end portion in the axial direction; and a through hole opposed to the slit and extending in the axial direction.

2. The fuel injection valve according to claim 1,

the tube has a second through hole extending in an axial direction of the tube between the through hole and the slit.

3. The fuel injection valve according to claim 2,

the second through-holes are formed on both sides of the through-hole symmetrically with respect to an axis of the through-hole.

4. The fuel injection valve according to claim 1,

the tube has: a third through hole having an axis orthogonal to the axis of the through hole and intersecting the through hole;

a second slit having the same axis as the third through hole, having a gap between both sides of the third through hole and the third through hole, and opening to the slit; and

and the fourth through hole is provided with an axis orthogonal to the axis of the through hole and is formed on two sides of the through hole in a mode of forming a gap between the fourth through hole and the through hole.

5. The fuel injection valve according to any one of claims 1 to 4,

the tube and the armature are joined together by welding, and the through hole is formed in a length that intersects the welded portion of the tube and the armature.