CN111279066B

CN111279066B - Fuel injection valve

Info

Publication number: CN111279066B
Application number: CN201780096255.4A
Authority: CN
Inventors: 川崎翔太; 宗实毅; 伊藤启祐
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-11-01
Filing date: 2017-11-01
Publication date: 2022-03-01
Anticipated expiration: 2037-11-01
Also published as: JPWO2019087325A1; JP6733999B2; WO2019087325A1; CN111279066A; PH12020550495A1

Abstract

Provided is a fuel injection valve for an internal combustion engine, which can maintain the spray characteristics in a good state even if impurities are accumulated. The fuel injection valve has a valve body (10) for opening and closing a valve seat (12), and fuel is injected from an injection hole (14) by operating the valve body (10), and a plurality of injection holes (14) are provided in an injection hole plate (13) attached to a downstream side opening portion of the valve seat (12), wherein the injection hole plate (13) includes a swirl chamber (18) and a fuel passage (17), the swirl chamber (18) provides swirl force to the fuel and injects the fuel from the injection hole (14) to the outside, the fuel passage (17) introduces the fuel into the swirl chamber (18), the fuel passage (17) has a recess (19) at a portion where a side wall portion and a bottom portion of the fuel passage (17) intersect, and the recess (19) is formed by recessing the side wall portion of the fuel passage (17) in a direction in which the fuel passage (17) is expanded.

Description

Fuel injection valve

Technical Field

The present invention relates to a fuel injection valve for supplying fuel to an internal combustion engine of an automobile or the like, and more particularly to a fuel injection valve for promoting atomization in spray characteristics.

Background

In recent years, in order to strengthen the regulation of exhaust gas of an internal combustion engine of an automobile or the like, atomization of fuel spray injected from a fuel injection valve is required, and various studies have been made on a method of realizing atomization by a swirl flow.

Patent document 1 discloses a fuel injection valve having a valve closing member disposed in a valve housing and cooperating with a valve seat surface, wherein a central opening is provided downstream of the valve seat surface, at least two tangential direction passages extend radially from the central opening, each of the tangential direction passages opens in a tangential direction in each swirl chamber, and a fixed amount opening for fuel communicates from the center of the swirl chamber to the outside.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 1-271656

Disclosure of Invention

Technical problem to be solved by the invention

In the fuel injection valve using the swirling flow as in the above-described conventional example, when the impurity contained in the fuel accumulates in the fuel passage, the fuel flow stagnates, and therefore the speed of the fuel flowing into the swirl chamber decreases. This reduces the angular velocity at which the fuel swirls. The angular velocity in the swirl chamber affects the performance of the spray spread angle after fuel injection and atomization of the spray. As a result, since impurities contained in the fuel are accumulated in the fuel passage, there is a possibility that a change in the spray spread angle and a deterioration in atomization of the spray occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel injection valve in which a recess for depositing impurities is provided in a swirl chamber, and thereby spray characteristics can be maintained in a good state even when impurities are deposited.

Technical scheme for solving technical problem

A fuel injection valve according to the present invention includes a valve element for opening and closing a valve seat, wherein fuel is injected from injection holes by operating the valve element, and a plurality of injection holes are provided in an injection plate attached to a downstream opening of the valve seat, wherein the injection plate includes: a swirl chamber that provides a swirl force to the fuel and injects the fuel from the injection hole to the outside; and a fuel passage for introducing fuel into the swirl chamber, the fuel passage having a recess at a portion where a side wall portion and a bottom portion of the fuel passage intersect, the recess being formed by recessing the side wall portion of the fuel passage in a direction in which the fuel passage expands.

Effects of the invention

In the fuel injection valve of the present invention, the fuel flowing from the valve seat opening portion into the swirl chamber flows into the injection hole while generating a swirl flow. The swirling flow is maintained in the injection hole, so that a thin liquid film is formed along the inner wall of the injection hole, and the thin liquid film is injected from the injection hole in a hollow conical shape, thereby promoting atomization of the fuel.

Further, since the recess formed by recessing the side wall portion of the fuel passage in the direction of expanding the fuel passage is provided at the portion where the side wall portion and the bottom portion of the fuel passage intersect, the flow velocity in the recess becomes lower than the flow velocity in the central portion of the fuel passage, and impurities in the fuel are likely to accumulate in the recess. Since the flow velocity in the recess is low, even if impurities accumulate in the recess, the average flow velocity in the fuel passage does not change substantially, and the influence on the angular velocity of the fuel that flows into the swirl chamber and swirls in the swirl chamber is small. The angular velocity in the swirl chamber affects the spray characteristics after fuel injection.

Therefore, by providing the recess in the fuel passage, it is possible to suppress changes in the spray spread angle and degradation of atomization of the spray due to accumulation of impurities in the fuel.

Drawings

Fig. 1 is a sectional view showing a fuel injection valve according to a first embodiment of the present invention.

Fig. 2 shows a fuel injection valve tip portion according to the first embodiment, (a) is a sectional view of the fuel injection valve tip portion, and (b) is a plan view of the line a-a as viewed in the direction of the arrows.

Fig. 3 is an enlarged plan view of fig. 2 (B), and is a cross-sectional view when viewed along the line B-B in the direction of the arrow.

Fig. 4 is a sectional view showing a fuel passage according to the first embodiment.

Fig. 5 is a sectional view showing a fuel passage according to a second embodiment of the present invention.

Fig. 6 shows a fuel injection valve tip portion according to a third embodiment of the present invention, wherein (a) is a sectional view of the fuel injection valve tip portion, and (b) is a plan view of the fuel injection valve tip portion as viewed along the line C-C in the direction of the arrows.

Fig. 7 is a sectional view showing a fuel passage of the third embodiment.

Fig. 8 is a sectional view showing a fuel passage according to a fourth embodiment of the present invention.

Fig. 9 shows a front end portion of a fuel injection valve according to a fifth embodiment of the present invention, wherein (a) is a sectional view of the front end portion of the fuel injection valve, and (b) and (C) are sectional views of the front end portion of the fuel injection valve as viewed along the arrows E-E and F-F, respectively.

Detailed Description

Implementation mode one

Fig. 1 to 4 are views showing a fuel injection valve according to a first embodiment of the present invention. In fig. 1, reference numeral 1 denotes a fuel injection valve, which includes a solenoid 4, a housing 5 serving as a yoke portion of a magnetic circuit, a core 6 serving as a fixed core portion of the magnetic circuit, a coil 7, an armature 8 serving as a movable core portion of the magnetic circuit, and a valve device 9, and the valve device 9 is composed of a valve element 10, a valve body 11, and a valve seat 12.

The valve main body 11 is pressed into the outer diameter portion of the core 6 and welded thereto. The armature 8 is press-fitted into the valve body 10 and then welded to the valve body 10. An orifice plate 13 is joined to the valve seat 12 by a weld 13 a. A plurality of injection holes 14 penetrating in the plate thickness direction are provided in the injection hole plate 13.

The injection hole plate 13 includes a swirl chamber 18 that provides a swirl force to the fuel and injects the fuel from the injection hole 14 to the outside, and a fuel passage 17 that introduces the fuel into the swirl chamber 18.

As shown in fig. 2 to 4, the fuel passage 17 has a recessed portion 19 having a rectangular cross-sectional shape at a portion where the side wall portion and the bottom portion intersect, and the recessed portion 19 is formed by recessing the side wall portion of the fuel passage 17 in a direction in which the fuel passage 17 is expanded.

The fuel passage 17 is formed to cross, the swirl chamber 18 is disposed at four positions on the downstream side of the fuel passage 17, and the injection hole 14 is provided at a position corresponding to the center of the swirl chamber 18.

In the fuel injection valve 1 configured as described above, when an operation signal is transmitted to the drive circuit of the fuel injection valve 1 by the control device of the engine, a current flows through the coil 7 of the fuel injection valve 1, a magnetic flux is generated in the magnetic circuit constituted by the armature 8, the core 6, the case 5, and the valve body 11, the armature 8 is attracted to operate toward the core 6, and the valve element 10 integrally formed with the armature 8 is separated from the seat portion 12a to form a gap.

Fuel is injected from the plurality of injection holes 14 into the engine intake passage through a gap between the valve seat portion 12a and the valve body 10 from the chamfered portion 15a of the ball 15 welded to the tip end portion of the valve body 10.

Next, when an operation stop signal is transmitted from the engine control device to the drive circuit of the fuel injection valve 1, the energization of the current in the coil 7 is stopped, the magnetic flux in the magnetic circuit is reduced, the gap between the valve element 10 and the valve seat portion 12a is closed by the compression spring 16 that presses the valve element 10 in the valve closing direction, and the fuel injection is completed.

The valve body 10 slides on the armature side surface 8a with respect to the guide portion of the valve body 11, and the armature upper surface 8b abuts against the lower surface of the core body 6 in the valve-opened state.

In the first embodiment, as shown in fig. 2 to 4, a plurality of (four in the drawing) swirl chambers 18 for applying a swirl force to the fuel are formed by recessing the upstream side of the orifice plate 13. A fuel passage 17 for introducing fuel into the swirl chamber 18 is provided corresponding to the swirl chamber 18. The fuel passage 17 communicates with the valve seat opening portion 12 b.

Thereby, the fuel flowing into the swirl chamber 18 from the valve seat opening portion 12b flows into the injection hole 14 while generating a swirl flow. The swirling flow is maintained in the injection hole 14, whereby a thin liquid film is formed along the inner wall of the injection hole, and the thin liquid film is injected from the injection hole 14 in a hollow conical shape, whereby atomization of the fuel is promoted.

In addition, in general, the flow velocity of the fuel flowing through the fuel passage 17 decreases as it approaches the wall surface, and therefore, impurities are likely to accumulate at the corner portions of the fuel passage 17. When impurities contained in the fuel accumulate in the fuel passage 17, the fuel flow is stagnated, and therefore, the speed of the fuel flowing into the swirl chamber 18 is reduced.

This reduces the angular velocity at which the fuel swirls. Since the angular velocity in the swirl chamber 18 affects the performance of the spray spread angle after fuel injection and atomization of the spray, impurities contained in the fuel may accumulate in the fuel passage, thereby causing a change in the spray spread angle and deterioration in the atomization of the spray.

Therefore, in the fuel injection valve 1 according to the first embodiment, as shown in fig. 2 to 4, a recessed portion 19 having a rectangular cross section is provided at a portion where the side wall portion and the bottom portion of the fuel passage 17 intersect, and the recessed portion 19 is formed by recessing the side wall portion of the fuel passage 17 in a direction in which the fuel passage 17 is expanded.

Since the flow velocity in the concave portion 19 is lower than the flow velocity in the central portion of the fuel passage 17, impurities in the fuel are likely to accumulate in the concave portion 19. Since the flow velocity in the recess 19 is slow, even if impurities accumulate in the recess 19, the average flow velocity in the fuel passage 17 does not change substantially, and the influence on the angular velocity of the fuel that flows into the swirling chamber 18 and swirls in the swirling chamber 18 is small.

In this way, by providing the recess 19 in the fuel passage 17, it is possible to suppress changes in the spray spread angle and degradation of spray atomization due to accumulation of impurities in the fuel.

As described above, the fuel injection valve of the present invention has the valve body 10 for opening and closing the valve seat 12, the fuel is injected from the injection hole 14 by operating the valve body 10, the injection hole plate 13 attached to the downstream side opening portion of the valve seat 12 is provided with the plurality of injection holes 14, wherein the injection hole plate 13 includes the swirl chamber 18 for supplying the swirl force to the fuel and injecting the fuel from the injection hole 14 to the outside, and the fuel passage 17 introduces the fuel into the swirl chamber 18, the fuel passage 17 has the concave portion 19 at the portion where the side wall portion and the bottom portion thereof intersect, the concave portion 19 is formed by recessing the side wall portion of the fuel passage 17 in the direction of expanding the fuel passage 17, and the flow velocity in the concave portion 19 becomes slower than the flow velocity in the swirl chamber 18, so that the impurities in the fuel are likely to be accumulated in the concave portion 19, and the flow velocity in the concave portion 19 becomes slow, therefore, even if the foreign matter is accumulated in the recess 19, the average flow velocity in the swirling chamber 18 does not substantially change, and therefore, the influence on the angular velocity of the swirling fuel becomes small, and it is possible to suppress the change in the spray spread angle and the deterioration of the atomization of the spray due to the accumulation of the foreign matter in the fuel.

Second embodiment

Fig. 5 is a sectional view of the fuel passage 17 according to the second embodiment of the present invention. Since the flow velocity of the fuel flow decreases as it approaches the wall surface, the distance between the wall surfaces in the recess 19 needs to be shortened to some extent in order to obtain the flow velocity reduction effect in the recess 19.

If the ratio of the length of the concave portion 19 to the side wall portion of the fuel passage 17 exceeds half, the distance between the wall surfaces in the concave portion 19 increases, and the effect of reducing the flow velocity in the concave portion 19 becomes weak.

Therefore, in the second embodiment, when the fuel passage 17 is viewed in a cross section perpendicular to the side wall portion and the bottom portion of the fuel passage 17, when the distance from the top to the bottom portion of the fuel passage 17 is defined as h and the length of the removal recess 19 in the side wall portion of the fuel passage 17 is defined as d, d/h is set to a relationship of > 0.5.

This enhances the effect of reducing the flow velocity in the recess 19, and thus, as described in the first embodiment, the effect of suppressing the change in the spray diffusion angle and the deterioration of the atomization of the spray due to the deposition of the impurities in the fuel can be obtained.

Third embodiment

Fig. 6 and 7 show a fuel injection valve according to a third embodiment of the present invention. The orifice plate 13 is composed of an upstream side plate 20 and a downstream side plate 21, the upstream side plate 20 constitutes the fuel passage 17 and a side wall portion of the swirl chamber 18, and the downstream side plate 21 constitutes the bottom of the fuel passage 17 and the swirl chamber 18 and opens the orifice 14.

After the fuel passage 17, the swirl chamber 18, and the recess 19 are machined in the upstream side plate 20, the upstream side plate 20 and the downstream side plate 21 are joined by welding, brazing, diffusion bonding, or the like.

By providing the nozzle plate 13 in a divided structure as described above, the processing of the concave portion 19 is facilitated, and productivity is improved.

Embodiment IV

Fig. 8 is a sectional view of the fuel passage 17 according to the fourth embodiment of the present invention. In the first to third embodiments, the cross section of the recess 19 is provided in a rectangular shape, but in the present embodiment, the cross section of the recess 19 is provided in a rounded corner shape that continuously expands in the side wall direction of the fuel passage 17.

Therefore, compared to the case where the cross section is formed in a rectangular shape, the distance between the wall surfaces in the recess 19 is reduced, and the effect of reducing the speed of the fuel flow in the recess 19 is enhanced, so that the effect of suppressing the change in the spray diffusion angle and the deterioration of the atomization of the spray due to the deposition of the impurities in the fuel can be obtained as described in the first embodiment.

Fifth embodiment

For the injection flow rate prediction of a general swirl type fuel injection valve, an equation based on the potential energy theory can be applied, and the relationship between the injection flow rate q, the cross-sectional area Si of the fuel passage, the injection hole diameter re, the swirl chamber diameter ri, and the ratio k between the cavity formed inside the injection hole and the injection hole diameter is: q. varies from k, Si, re/ri.

Here, when the impurities in the fuel are accumulated in the recess 19, the cross-sectional area Si of the fuel passage 17 changes, and therefore, there is a problem that the injection flow rate q changes.

Therefore, in the fifth embodiment, as shown in fig. 9, a region not having the recessed portion 19 is provided in a part of the fuel passage 17, and further, the region not having the recessed portion 19 of the fuel passage 17 is provided on the downstream side with respect to the region having the recessed portion 19 of the fuel passage 17.

By providing the region having the recessed portion 19 on which impurities in the fuel are likely to accumulate on the upstream side, impurities in the fuel are less likely to accumulate in the fuel passage 17 in the region having no recessed portion 19 on the downstream side, and the cross-sectional area Si of the fuel passage 17 can be ensured to be constant.

This prevents the injection flow rate from changing even when impurities in the fuel accumulate in the recess 19.

The present invention is not limited to the embodiments, and various design changes can be made, and the embodiments can be freely combined or appropriately modified and omitted within the scope of the present invention.

Description of the symbols

1 a fuel injection valve; 4, an electromagnetic device; 5, a shell; 6 a core body; 7, coils; 8 an armature; 8a armature side; 8b armature upper surface; 9 a valve means; 10 a valve core; 11 a valve body; 12 valve seats; 12a valve seat portion; 12b a valve seat opening part; 13, a spray orifice plate; 14, spraying holes; 15 spheres; 15a chamfer; 16 a compression spring; 17 a fuel passage; 18 a swirl chamber; 19 a recess; 20 an upstream side plate; 21 downstream side plate.

Claims

1. A fuel injection valve having a valve body for opening and closing a valve seat, wherein fuel is injected from injection holes by operating the valve body, wherein a plurality of the injection holes are provided in an injection hole plate attached to a downstream opening portion of the valve seat,

the orifice plate includes:

a swirl chamber that provides a swirl force to the fuel and injects the fuel from the injection hole to the outside; and

a fuel passage that introduces fuel into the swirl chamber,

the fuel passage has a recessed portion at a portion where a side wall portion and a bottom portion of the fuel passage intersect, and the recessed portion is formed by recessing the side wall portion of the fuel passage in a direction in which the fuel passage expands.

2. The fuel injection valve according to claim 1,

when the fuel passage is viewed in a cross section perpendicular to the side wall portion and the bottom portion of the fuel passage, when a distance from the top to the bottom portion of the fuel passage is defined as h, and a length of the removal recess portion of the side wall portion of the fuel passage is defined as d, a relationship of d/h > 0.5 is obtained.

3. The fuel injection valve according to claim 1 or 2,

the injection hole plate is configured by an upstream side plate and a downstream side plate, the upstream side plate configuring the fuel passage and a side wall portion of the swirl chamber, the downstream side plate configuring a bottom portion of the fuel passage and the swirl chamber and having the injection hole opened therein.

4. The fuel injection valve according to claim 1 or 2,

the recess has a rectangular cross section.

5. The fuel injection valve according to claim 1 or 2,

the recess has a rounded-corner-shaped cross section that continuously expands in the direction of the side wall of the fuel passage.

6. The fuel injection valve according to claim 1 or 2,

an area having no recess is provided in a part of the fuel passage.

7. The fuel injection valve according to claim 6,

the region of the fuel passage not having the recessed portion is provided on the downstream side of the fuel passage with respect to the region of the fuel passage having the recessed portion.

8. The fuel injection valve according to claim 1 or 2,

the fuel passage is formed to cross, and the swirl chamber is disposed at four locations on the downstream side of the fuel passage.